1,572 research outputs found
Dynamics of Enceladus and Dione inside the 2:1 Mean-Motion Resonance under Tidal Dissipation
In a previous work (Callegari and Yokoyama 2007, Celest. Mech. Dyn. Astr.
vol. 98), the main features of the motion of the pair Enceladus-Dione were
analyzed in the frozen regime, i.e., without considering the tidal evolution.
Here, the results of a great deal of numerical simulations of a pair of
satellites similar to Enceladus and Dione crossing the 2:1 mean-motion
resonance are shown. The resonance crossing is modeled with a linear tidal
theory, considering a two-degrees-of-freedom model written in the framework of
the general three-body planar problem. The main regimes of motion of the system
during the passage through resonance are studied in detail. We discuss our
results comparing them with classical scenarios of tidal evolution of the
system. We show new scenarios of evolution of the Enceladus-Dione system
through resonance not shown in previous approaches of the problem.Comment: 36 pages, 12 figures. Accepted in Celestial Mechanics and Dynamical
Astronom
Interplay of tidal evolution and stellar wind braking in the rotation of stars hosting massive close-in planets
This paper deals with the application of the creep tide theory (Ferraz-Mello,
Cel. Mech. Dyn. Astron. vol. 116, 109, 2013) to the study of the rotation of
stars hosting massive close-in planets. The stars have nearly the same tidal
relaxation factors as gaseous planets and the evolution of their rotation is
similar to that of close-in hot Jupiters: they tidally evolve towards a
stationary solution. However, stellar rotation may also be affected by stellar
wind braking. Thus, while the rotation of a quiet host star evolves towards a
stationary attractor with a frequency () times the orbital mean-motion
of the companion, the continuous loss of angular momentum in an active star
displaces the stationary solution towards slower values: Active host stars with
big close-in companions tend to have rotational periods larger than the orbital
periods of their companions. The study of some hypothetical examples shows that
because of tidal evolution, the rules of gyrochronology cannot be used to
estimate the age of one system with a large close-in companion, no matter if
the star is quiet or active, if the current semi-major axis of the companion is
smaller than 0.03--0.04 AU. Details on the evolution of the systems: CoRoT
LRc06E21637, CoRoT-27, Kepler-75, CoRoT-2, CoRoT-18, CoRoT-14 and on
hypothetical systems with planets of mass 1--4 M_Jup in orbit around a star
similar to the Sun are given.Comment: 22 pages, 8 figures; Publication in Ap
Direito adquirido na Constituição e sua repercussão nos direitos individuais do trabalhador
Este trabalho tem por objeto a questão do direito adquirido, em face dos contratos sucessivos em sede trabalhista, conforme a Constituição Federal. O problema é particularmente relevante por conta do caráter imperativo das normas trabalhistas e do princípio da proteção ao trabalhador: um regime legal novo só obriga se mantém ou amplia as condições (vantagens) estabelecidas pelo regime anterior revogado. Propõe-se demonstrar que o princípio se submete a uma ponderação com outros princípios constitucionais, não podendo ser tomado em termos de uma supremacia hierárquica absoluta
O conceito peirceano de metáfora e suas interpretações: limites do verbocentrismo
This paper aims to discuss the concept of metaphor as an iconic sign, as it was proposed by Charles Sanders Peirce in his Theory of Signs. Next to a brief introduction consisting in recalling the description of the hypoicons (signs whose representative function is based on the similarity between the representamen and its object), we consider the strong tendency to what we call the verbocentric reading of the Peircian metaphor, evidenced in some essential works for the dissemination of semiotic studies. With this expression, we refer to the exclusive, or even preferential, linkage of the metaphorical iconic sign to the linguistic code, which emphasizes its discursive character, making this semiotic concept coincide with the figure of speech that we know from classical poetics. Admitting the existence of metaphorical constructions that go beyond verbal expression and considering that the Peircean writings do not make any explicit restriction on the type of language that should materialize the metaphorical hypoicon, we adopted a range of divergent interpretation from the dominant reading, in which, through theoretical reasoning and by analyzing some illustrative cases, we attempt to demonstrate the extension of the concept under consideration to forms of non-linguistic representation. To this end, we undertake an interpretation of the Peircean concept strictly based on the analysis of his original description, in which we emphasize the meaning of some key-expressions as “representative character” and “representing a parallelism”. We also explore the concept of "third firstness", which is associated by inference to the metaphorical iconic sign, questioning one of its developments, namely the subordination of the Peircean metaphor to the symbolic mode of representation — which we presume to be the basis of the verbocentric reading.O presente trabalho tem por objetivo discutir o conceito de metáfora como signo icônico, conforme proposto por Charles Sanders Peirce em sua Teoria Geral dos Signos. Após uma breve introdução, em que revisitamos na origem a descrição dos signos icônicos ou hipoícones (aqueles cuja função representativa se baseia na semelhança entre representâmen e objeto), passamos a examinar a forte tendência, constatada em obras essenciais para a divulgação dos estudos semióticos, ao que chamamos de leitura verbocêntrica da metáfora peirceana. Com essa expressão, referimo-nos à vinculação exclusiva, ou mesmo preferencial, do signo icônico metafórico ao domínio do código linguístico, a qual lhe enfatiza certo caráter discursivo, fazendo coincidir essa categoria semiótica com a figura de linguagem que conhecemos desde a poética clássica. Admitindo a existência de construções metafóricas que extrapolam os limites do verbal, e considerando que o texto peirceano não explicita qualquer restrição quanto ao tipo de linguagem em que deve materializar-se o hipoícone metafórico, adotamos uma linha de interpretação divergente da leitura dominante, em que procuramos demonstrar, através de argumentação teórica e também de análises ilustrativas, a extensão do conceito em exame às formas de representação não linguísticas. Para tanto, empreendemos uma releitura do conceito peirceano a partir da análise de sua descrição original, sublinhando a interpretação das expressões-chave “caráter representativo” e “representação de um paralelismo”. Exploramos ainda o conceito de “terceira primeiridade”, que se associa por dedução ao signo icônico metafórico, questionando um de seus desdobramentos, qual seja a subordinação da metáfora peirceana ao modo de representação simbólico — em que reconhecemos o principal fundamento da leitura verbocêntrica
Effect of hyperbaric oxygen therapy: case report of patient with hepato-pulmonary syndrome on waiting list for liver transplantation
INTRODUÇÃO: As doenças hepáticas apresentam índices de morbidade e mortalidade elevados e quando em estágio avançado têm o transplante do fígado como forma de tratamento potencialmente curativo e eficaz, embora este não possa ser oferecido a todos os pacientes. Isso faz com que essas doenças sejam consideradas problema de saúde pública em todo o mundo. Os cuidados clínicos para manter o paciente com condições de esperar e suportar o transplante continua um desafio. RELATO DO CASO: Mulher com 65 anos de idade, procedente do Recife, com diagnóstico de cirrose hepática secundária a vírus C apresentava dispnéia importante aos mínimos esforços tendo PaO2 de repouso de 60 mmHg e O2 de 90%, com espirometria normal. Realizou eco-Doppler que evidenciou shunt pulmonar importante. Durante a triagem em lista de transplante (MELD de 16 em agosto de 2006) foi optado pelo início de sessões de oxigenioterapia em câmara hiperbárica a fim de melhorar a sintomatologia respiratória da síndrome hepato-pulmonar. Apresentava melhora substancial da tolerância ao exercício após a terapia hiperbárica, assim como os valores do PaO2 à gasometria. Realizou 10 sessões de oxigenioterapia em câmara hiperbárica. Realizou transplante hepático em outubro de 2007 e vem em acompanhamento ambulatorial com boa evolução e melhora substancial da dispnéia. CONCLUSÃO: Constatou-se melhora da condição hepato-pulmonar após oxigenoterapia hiperbárica. Desta forma, ela surge como mais uma ferramenta para o tratamento das doenças hepáticas, devendo ser realizados outros estudos que avaliem sua utilização clínica.INTRODUCTION: Progressive impairment of liver function in hepatic cirrhosis is a major medical problem with limited therapeutic approaches, and liver transplantation is the only effective therapy. Reports of alternatives for liver function improvement on patients awaiting liver transplantation may include hyperbaric oxygen therapy. CASE REPORT: A 65-year old woman had diagnosis of hepatitis C and liver cirrhosis during treatment for breast cancer. In addition to liver failure and a MELD of 16, the patient presented hypoxemia with a PaO2 of 60 mmHg, and further evaluation with eco-Doppler revealed a hepatopulmonary syndrome. Clinical improvement was attempted with hyperbaric oxygeniotherapy, and substantial clinical and laboratorial improvement was acheived after 10 sessions, with significant improvement on cyanosis and arterial gas values. CONCLUSION: Oxygen therapy was effective in the improvement of dyspnea and hypoxemia secondary to hepatopulmonary syndrome in a patient with liver cirrhosis indicated for liver transplantation. The positive results of this treatment suggest that hyperbaric oxygen therapy may help on improvement of symptoms of hepatopulmonary syndrome
Poetics and Politics of the face in the age of smart images
O presente artigo explora algumas inflexões contemporâneas no estatuto do rosto. Na arte contemporânea, em sistemas de vídeo-vigilância, no marketing, na pornografia etc. as tecnologias de detecção e reconhecimento facial parecem espraiar-se sobre uma vasta gama de domínios. Sem a pretensão de esgotar este campo, propomos traçar algumas linhas de força que nos ajudem a compreender o que está em jogo nessa reconfiguração estética e política dos rostos. A partir de noções que buscamos no pensamento de autores como Michel Foucault, Giorgio Agamben, Gilles Deleuze e Félix Guattari, cartografamos algumas tensões entre ação e representação, cristalizadas no estatuto contemporâneo do rosto.This article explores some contemporary inflections about the status of the face. In contemporary art, in surveillance systems, in marketing practices, in pornography etc.; facial recognition and detection technologies seem to be spreading over a wide range of domains. Not intending to exhaust the theme, we will try to draw some lines of force that aid us in understanding what is at stake in this aesthetic and political reconfiguration of the faces. From some notions we have sought in the works of authors like Michel Foucault, Giorgio Agamben, Gilles Deleuze and Félix Guattari, we have mapped some tensions between action and representation, crystallized in the contemporary status of the face
Efficient Strategies for Graph Pattern Mining Algorithms on GPUs
Graph Pattern Mining (GPM) is an important, rapidly evolving, and computation
demanding area. GPM computation relies on subgraph enumeration, which consists
in extracting subgraphs that match a given property from an input graph.
Graphics Processing Units (GPUs) have been an effective platform to accelerate
applications in many areas. However, the irregularity of subgraph enumeration
makes it challenging for efficient execution on GPU due to typical uncoalesced
memory access, divergence, and load imbalance. Unfortunately, these aspects
have not been fully addressed in previous work. Thus, this work proposes novel
strategies to design and implement subgraph enumeration efficiently on GPU. We
support a depth-first search style search (DFS-wide) that maximizes memory
performance while providing enough parallelism to be exploited by the GPU,
along with a warp-centric design that minimizes execution divergence and
improves utilization of the computing capabilities. We also propose a low-cost
load balancing layer to avoid idleness and redistribute work among thread warps
in a GPU. Our strategies have been deployed in a system named DuMato, which
provides a simple programming interface to allow efficient implementation of
GPM algorithms. Our evaluation has shown that DuMato is often an order of
magnitude faster than state-of-the-art GPM systems and can mine larger
subgraphs (up to 12 vertices).Comment: Accepted for publication on IEEE 34th International Symposium on
Computer Architecture and High Performance Computing (SBAC-PAD'22
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