Effect of the Canting of Local Anisotropy Axes on Ground-State Properties of a Ferrimagnetic Chain with Regularly Alternating Ising and Heisenberg Spins

The effect of the canting of local anisotropy axes on the ground-state phase diagram and magnetization of a ferrimagnetic chain with regularly alternating Ising and Heisenberg spins is exactly examined in an arbitrarily oriented magnetic field. It is shown that individual contributions of Ising and Heisenberg spins to the total magnetization basically depend on the spatial orientation of the magnetic field and the canting angle between two different local anisotropy axes of the Ising spins.Comment: 3 pages, 3 figure

On wave interference in planet migration: dead zone torques modified by active zone forcing

We investigate planetary migration in the dead zone of a protoplanetary disk where there are a set of spiral waves propagating inward due to the turbulence in the active zone and the Rossby wave instability (RWI), which occurs at the transition between the dead and active zones. We perform global 3D unstratified magnetohydrodynamical (MHD) simulations of a gaseous disk with the FARGO3D code, using weak gradients in the static resistivity profiles that trigger the formation of a vortex at the outer edge of the dead zone. We find that once the Rossby vortex develops, spiral waves in the dead zone emerge and interact with embedded migrating planets by wave interference, which notably changes their migration. The inward migration becomes faster depending on the mass of the planet, due mostly to the constructive (destructive) interference between the outer (inner) spiral arm of the planet and, the destruction of the dynamics of the horseshoe region by means of the set of background spiral waves propagating inward. The constructive wave interference produces a more negative Lindblad differential torque which inevitably leads to an inward migration. Lastly, for massive planets embedded in the dead zone, we find that the spiral waves can create an asymmetric wider and depeer gap than in the case of $\alpha$-disks, and can prevent the formation of vortices at the outer edge of the gap. The latter could generate a faster or slower migration compared to the standard type-II migration.Comment: 18 pages, 14 figures, accepted for publication in Ap

JOGOS SÉRIOS PARA REABILITAÇÃO DE MEMBROS INFERIORES DE PACIENTES PÓS-AVC UTILIZANDO KINECT, AMBIENTES VIRTUAIS E SINAIS MIOELÉTRICOS

Incapacidades motoras são os sintomas mais comuns após o Acidente Vascular Cerebral (AVC). Quando os membros inferiores são afetados, a realização de atividades da vida diária fica comprometida. Um desenvolvimento recente no campo da reabilitação é o uso de jogos sérios utilizando em ambientes virtuais (AV), e sensores de movimento associados ao biofeedback sEMG. Por meio deste biofeedback, os sinais mioelétricos do músculo são convertidos em informações visuais e sonoras, permitindo ao paciente controlar sua atividade muscular. O objetivo deste trabalho é conceber e avaliar uma tecnologia assistiva (TA), na forma de jogos sérios, focada na reabilitação de membros inferiores de voluntários pós-AVC. A TA é composta por AVs, e por sensores de movimento e de eletromiografia de superfície (sEMG). O sistema foi desenvolvido levando-se em consideração as limitações funcionais e habilidades residuais do público alvo, buscando criar um ambiente motivador e de fácil uso. A TA é capaz de fornecer um biofeedback em tempo real, mostrando na tela do AV o nível de ativação muscular do usuário. Os AVs desenvolvidos têm como objetivo motivar os voluntários, a fim de que realizem movimentos de levantar-se/sentar-se e extensão/flexão de joelho. Para avaliar o sistema foram realizados testes com nove voluntários pós-AVC. Os resultados das avaliações, feitas por meio das métricas System Usability Scale (SUS), Goal Attainment Scale (GAS) e Questionário de Avaliação do Ambiente Virtual (QAAV), revelaram que o sistema foi bem avaliado pelos voluntários, ressaltando-se alguns pontos a serem melhorados nas próximas versões do sistema. Adicionalmente, uma análise feita nos sinais mioelétricos e amplitude dos movimentos revelou que o sistema foi eficiente no que se propôs a realizar. Palavras-chave: acidente vascular cerebral, jogos sérios, reabilitação, biofeedback, eletromiografia e ambientes virtuais

Compactness in the Thermal Evolution of Twin Stars

In this work, we study for the first time the thermal evolution of twin star pairs, i.e., stars that present the same mass but different radius and compactness. We collect available equations of state that give origin to a second branch of stable compact stars with quarks in their core. For each equation of state, we investigate the particle composition inside stars and how differently each twin evolves over time, which depends on the central density/pressure and consequent crossing of the threshold for the Urca cooling process. We find that, although the general stellar thermal evolution depends on mass and particle composition, withing one equation of state, only twin pairs that differ considerably on compactness can be clearly distinguished by how they cool down

Mapping dynamical systems onto complex networks

A procedure to characterize chaotic dynamical systems with concepts of complex networks is pursued, in which a dynamical system is mapped onto a network. The nodes represent the regions of space visited by the system, while edges represent the transitions between these regions. Parameters used to quantify the properties of complex networks, including those related to higher order neighborhoods, are used in the analysis. The methodology is tested for the logistic map, focusing the onset of chaos and chaotic regimes. It is found that the corresponding networks show distinct features, which are associated to the particular type of dynamics that have generated them.Comment: 13 pages, 8 eps files in 5 figure

Mother Centriole Distal Appendages Mediate Centrosome Docking at the Immunological Synapse and Reveal Mechanistic Parallels with Ciliogenesis.

Cytotoxic T lymphocytes (CTLs) are highly effective serial killers capable of destroying virally infected and cancerous targets by polarized release from secretory lysosomes. Upon target contact, the CTL centrosome rapidly moves to the immunological synapse, focusing microtubule-directed release at this point [1-3]. Striking similarities have been noted between centrosome polarization at the synapse and basal body docking during ciliogenesis [1, 4-8], suggesting that CTL centrosomes might dock with the plasma membrane during killing, in a manner analogous to primary cilia formation [1, 4]. However, questions remain regarding the extent and function of centrosome polarization at the synapse, and recent reports have challenged its role [9, 10]. Here, we use high-resolution transmission electron microscopy (TEM) tomography analysis to show that, as in ciliogenesis, the distal appendages of the CTL mother centriole contact the plasma membrane directly during synapse formation. This is functionally important as small interfering RNA (siRNA) targeting of the distal appendage protein, Cep83, required for membrane contact during ciliogenesis [11], impairs CTL secretion. Furthermore, the regulatory proteins CP110 and Cep97, which must dissociate from the mother centriole to allow cilia formation [12], remain associated with the mother centriole in CTLs, and neither axoneme nor transition zone ciliary structures form. Moreover, complete centrosome docking can occur in proliferating CTLs with multiple centriole pairs. Thus, in CTLs, centrosomes dock transiently with the membrane, within the cell cycle and without progression into ciliogenesis. We propose that this transient centrosome docking without cilia formation is important for CTLs to deliver rapid, repeated polarized secretion directed by the centrosome.We thank the Wellcome Trust for funding to GMG (075880) and CIMR (100140).This is the final version of the article. It was first available from Elsevier via http://dx.doi.org/10.1016/j.cub.2015.10.02

The role of the initial surface density profiles of the disc on giant planet formation: comparing with observations

In order to explain the main characteristics of the observed population of extrasolar planets and the giant planets in the Solar System, we need to get a clear understanding of which are the initial conditions that allowed their formation. To this end we develop a semi-analytical model for computing planetary systems formation based on the core instability model for the gas accretion of the embryos and the oligarchic growth regime for the accretion of the solid cores. With this model we explore not only different initial discs profiles motivated by similarity solutions for viscous accretion discs, but we also consider different initial conditions to generate a variety of planetary systems assuming a large range of discs masses and sizes according to the last results in protoplanetary discs observations. We form a large population of planetary systems in order to explore the effects in the formation of assuming different discs and also the effects of type I and II regimes of planetary migration, which were found to play fundamental role in reproducing the distribution of observed exoplanets. Our results show that the observed population of exoplanets and the giant planets in the Solar System are well represented when considering a surface density profile with a power law in the inner part characterized by an exponent of -1, which represents a softer profile when compared with the case most similar to the MMSN model case.Comment: 14 pages, 12 figures, MNRAS, 412, 211

Adaptação aos impactos das mudanças climáticas na perspectiva do plano diretor da cidade do Recife

Defining measures for climate change adaptation is a complex task given the existence of social, environmental, and economic demands, particularly in cities with poor urban infrastructure. As a result of analyzing the revision process of the Recife Master Plan, it is possible to observe that a reduction in the social and environmental vulnerabilities has implied carrying out more consistent studies, which may entail the implementation of structuring measures, and that environmental sustainability requires multilevel governance, with policy reforms on a global, regional and local scale, difficult to implement in the short term, although necessary for refocusing climate policies and for overcoming the inability to provide resources for a tailored adaptation infrastructure. The path to building a resilient city that provides a safer environment for the future depends on an inclusive development model, which enables the population to improve urban conditions and minimize the impacts brought about by extreme weather events.É complexa a tarefa de definir medidas de adaptação às mudanças climáticas diante da existência de demandas sociais, ambientais e econômicas, sobretudo em cidades que apresentam infraestrutura urbana deficiente. Como resultado da análise do processo de revisão do Plano Diretor do Recife (PDDR), vê-se que a redução das vulnerabilidades socioambientais implica a realização de estudos mais consistentes, que possam acarretar a implementação de medidas estruturadoras, e que a sustentabilidade ambiental demanda uma governança multinível, com reformas políticas em escala global, regional e local, de difícil aplicação no curto prazo, mas necessárias para reorientar as políticas do clima e superar a inabilidade de prover os recursos para uma infraestrutura adequada à adaptação. O caminho para construir uma cidade resiliente, que proporcione um ambiente mais seguro para as futuras gerações, depende de um modelo de desenvolvimento inclusivo, que permita melhorar as condições urbanas para a população e minimizar os impactos ocasionados pelos eventos climáticos extremos

The role of the initial surface density profiles of the disc on giant planet formation: comparing with observations

In order to explain the main characteristics of the observed population of extrasolar planets and the giant planets in the Solar System, we need to get a clear understanding of which are the initial conditions that allowed their formation. To this end we develop a semi-analytical model for computing planetary systems formation based on the core instability model for the gas accretion of the embryos and the oligarchic growth regime for the accretion of the solid cores. With this model we explore not only different initial discs profiles motivated by similarity solutions for viscous accretion discs, but we also consider different initial conditions to generate a variety of planetary systems assuming a large range of discs masses and sizes according to the last results in protoplanetary discs observations. We form a large population of planetary systems in order to explore the effects in the formation of assuming different discs and also the effects of type I and II regimes of planetary migration, which were found to play fundamental role in reproducing the distribution of observed exoplanets. Our results show that the observed population of exoplanets and the giant planets in the Solar System are well represented when considering a surface density profile with a power law in the inner part characterized by an exponent of -1, which represents a softer profile when compared with the case most similar to the MMSN model case.Comment: 14 pages, 12 figures, MNRAS, 412, 211