Pulsar magnetospheres: numerical simulations of large amplitude electron-positron oscillations

The numerical simulation of non-linear electron-positron oscillations is reported, showing the evolution of the electric field and the plasma number density for large amplitude disturbances. Sharp density gradients and changes in the oscillation frequency are demonstrated, and a new analytical framework is presented to illustrate these phenomena, particularly in the context of pulsar plasmas

Towards an efficient prover for the C1 paraconsistent logic

The KE inference system is a tableau method developed by Marco Mondadori which was presented as an improvement, in the computational efficiency sense, over Analytic Tableaux. In the literature, there is no description of a theorem prover based on the KE method for the C1 paraconsistent logic. Paraconsistent logics have several applications, such as in robot control and medicine. These applications could benefit from the existence of such a prover. We present a sound and complete KE system for C1, an informal specification of a strategy for the C1 prover as well as problem families that can be used to evaluate provers for C1. The C1 KE system and the strategy described in this paper will be used to implement a KE based prover for C1, which will be useful for those who study and apply paraconsistent logics.Comment: 16 page

O desafio da previsão do comportamento fora-do-plano de edifícios existentes de alvenaria

O comportamento sísmico de estruturas existentes em alvenaria é muito condicionado pelo seu comportamento fora-do-plano, originando os chamados mecanismos locais, existindo diversas metodologias que tentam prever o comportamento deste tipo de estruturas e/ou modos de colapso. Este trabalho pretende resumir os principais resultados obtidos num evento subordinado ao tema “Methods and challenges on the out-of-plane assessment of existing masonry buildings”, inserido na 9th IMC (2014) em Guimarães, com o objectivo de prever o comportamento de duas estruturas em alvenaria utilizando métodos de análise correntemente utilizados na análise sísmica de estruturas existentes. Relativamente às estruturas estudadas, uma destas era materializada em alvenaria tradicional de pedra de dois panos, sendo a outra construída em alvenaria de tijolo. Estas estruturas foram ensaiadas à escala real na mesa sísmica do LNEC. No final do presente artigo apresentam-se os principais resultados obtidos com as simulações realizadas e sua comparação com o comportamento real das estruturas.The seismic behaviour of existing masonry buildings is governed by the out-of-plane behaviour in the form of the so-called local mechanisms. Despite recent advances within the area, there are several different methodologies to predict the behaviour of these local mechanisms. The article herein submitted aims to present the main results obtained on a workshop entitled “Methods and challenges on the out-of-plane assessment of existing masonry buildings”, within the 9th IMC (2014) held at Guimarães, with the objective of predict the behaviour of masonry structures making use of any available method for the seismic analysis. Regarding the studied structures, one was built on traditional doubleleaf stone masonry while the other was built on brick masonry, and they were tested at LNEC shaking table. The main conclusions are presented at the end of the article, namely the obtained results with the prediction and the observed experimental behavior

A dual flow bioreactor with controlled mechanical stimulation for cartilage tissue engineering

In cartilage tissue engineering bioreactors can create a controlled environment to study chondrocyte behavior under mechanical stimulation or produce chondrogenic grafts of clinically relevant size. Here we present a novel bioreactor, which combines mechanical stimulation with a two compartment system through which nutrients can be supplied solely by diffusion from opposite sides of a tissue engineered construct. This design is based on the hypothesis that creating gradients of nutrients, growth factors and growth factor antagonists can aid in the generation of zonal tissue engineered cartilage. Computational modeling predicted that the design facilitates the creation of a biologically relevant glucose gradient. This was confirmed by quantitative glucose measurements in cartilage explants. In this system it is not only possible to create gradients of nutrients, but also of anabolic or catabolic factors. Therefore, the bioreactor design allows control over nutrient supply and mechanical stimulation useful for in vitro generation of cartilage constructs that can be used for the resurfacing of articulated joints or as a model for studying OA disease progression

Constructions of algebraic lattices

In this work we present constructions of algebraic lattices in Euclidean space with optimal center density in dimensions 2, 3, 4, 6, 8 and 12, which are rotated versions of the lattices Λn, for n = 2,3,4,6,8 and K12. These algebraic lattices are constructed through twisted canonical homomorphism via ideals of a ring of algebraic integers. Mathematical subject classification: 18B35, 94A15, 20H10.49350

Avaliação experimental do comportamento fora do plano de paredes de alvenaria de adobe

Com vista a colmatar a escassez de informação acerca do comportamento e propriedades mecânicas das construções em alvenaria de adobe existentes na região de Aveiro, tem-se vindo a realizar várias campanhas experimentais. Procurando identificar aspectos tais como a rigidez, a capacidade resistente, a dissipação de energia e os mecanismos de colapso, essas campanhas têm incluído levantamentos dimensionais, estudos da composição granulométrica dos diferentes adobes da região, ensaios de caracterização do comportamento mecânico deste material (em tracção e compressão), ensaios cíclicos quase-estáticos em alvenaria (fora do plano e no plano), ensaios de caracterização dinâmica, etc. Neste artigo apresentam-se os principais resultados de um ensaio cíclico quase-estático para fora do plano, complementado com ensaios dinâmicos realizados sobre paredes de alvenaria de adobe de uma construção existente. Procura-se assim contribuir para uma melhor caracterização das construções já edificadas, tendo em vista a interpretação das patologias estruturais mais comuns, a calibração de modelos numéricos, a avaliação da segurança e o desenvolvimento de adequadas soluções de reforço

Social presence, embarrassment, and nonverbal behavior

Nonverbal behaviors in response to viewing slides depicting nude males, nude females, erotic couples and neutral pictures, either alone or in the presence of two unfamiliar individuals, were studied in 22 female and 16 male university students. Participants were unaware of being videorecorded. Results revealed discrepancies between self-reported embarrassment and nonverbal behaviors supposedly expressive of embarrassment. Although self-reported embarrassment was higher when certain types of slides were viewed in the presence of others than when they were viewed alone, we observed significantly fewer lip movements, gaze shifts, face touches, downward gazes, and downward head movements in the presence of unfamiliar individuals than in the alone condition. We also compared behaviors during slide exposure and during the inter-slide intervals. For 9 out of 11 coded behaviors, frequencies were significantly higher during inter-slide intervals than during slide presentation. We argue that this is probably due to the fact that visual attention to the slides inhibited nonverbal behaviors. The results cast doubt on the possibility of inferring the internal state of an emotion such as embarrassment by analyzing nonverbal behaviors without taking account of the social setting in which such observations are made

A New Cosmological Scenario in String Theory

We consider new cosmological solutions with a collapsing, an intermediate and an expanding phase. The boundary between the expanding (collapsing) phase and the intermediate phase is seen by comoving observers as a cosmological past (future) horizon. The solutions are naturally embedded in string and M-theory. In the particular case of a two-dimensional cosmology, space-time is flat with an identification under boost and translation transformations. We consider the corresponding string theory orbifold and calculate the modular invariant one-loop partition function. In this case there is a strong parallel with the BTZ black hole. The higher dimensional cosmologies have a time-like curvature singularity in the intermediate region. In some cases the string coupling can be made small throughout all of space-time but string corrections become important at the singularity. This happens where string winding modes become light which could resolve the singularity. The new proposed space-time casual structure could have implications for cosmology, independently of string theory.Comment: 28 pages, 3 figures; v2: Added new subsection relating two-dimensional model to BTZ black hole, typos corrected and references added; v3: minor corrections, PRD versio

Three-dimensional kinematic analysis of upper and lower limb motion during gait of post-stroke patients

The aim of this study was to analyze the alterations of arm and leg movements of patients during stroke gait. Joint angles of upper and lower limbs and spatiotemporal variables were evaluated in two groups: hemiparetic group (HG, 14 hemiparetic men, 53 ± 10 years) and control group (CG, 7 able-bodied men, 50 ± 4 years). The statistical analysis was based on the following comparisons (P ≤ 0.05): 1) right versus left sides of CG; 2) affected (AF) versus unaffected (UF) sides of HG; 3) CG versus both the affected and unaffected sides of HG, and 4) an intracycle comparison of the kinematic continuous angular variables between HG and CG. This study showed that the affected upper limb motion in stroke gait was characterized by a decreased range of motion of the glenohumeral (HG: 6.3 ± 4.5, CG: 20.1 ± 8.2) and elbow joints (AF: 8.4 ± 4.4, UF: 15.6 ± 7.6) on the sagittal plane and elbow joint flexion throughout the cycle (AF: 68.2 ± 0.4, CG: 46.8 ± 2.7). The glenohumeral joint presented a higher abduction angle (AF: 14.2 ± 1.6, CG: 11.5 ± 4.0) and a lower external rotation throughout the cycle (AF: 4.6 ± 1.2, CG: 22.0 ± 3.0). The lower limbs showed typical alterations of the stroke gait patterns. Thus, the changes in upper and lower limb motion of stroke gait were identified. The description of upper limb motion in stroke gait is new and complements gait analysis.53754

The geometry of null rotation identifications

The geometry of flat spacetime modded out by a null rotation (boost+rotation) is analysed. When embedding this quotient spacetime in String/M-theory, it still preserves one half of the original supersymmetries. Its connection with the BTZ black hole, supersymmetric dilatonic waves and one possible resolution of its singularity in terms of nullbranes are also discussed.Comment: 1+18 pages, 5 figures. v2 references adde