An objective perspective for classic flow classification criteria

Four classic criteria used to the classification of complex flows are discussed here. These criteria are useful to identify regions of the flow related to shear, elongation or rigid-body motion. These usual criteria, namely $Q$, $\Delta$, $\lambda_{2}$ and $\lambda_{cr}/\lambda_{ci}$, use the fluid's rate-of-rotation tensor, which is known to vary with respect to a reference frame. The advantages of using objective (invariant with respect to a general transformation on the reference frame) criteria are discussed in the present work. In this connection, we construct versions of classic criteria replacing standard vorticity, a non-objective quantity, by effective vorticity, a rate of rotation tensor with respect to the angular velocity of the eigenvectors of the strain rate tensor. The classic criteria and their corresponding objective versions are applied to classify two complex flows: the transient ABC flow and the flow through the abrupt 4:1 contraction. It is shown that the objective versions of the criteria provide richer information on the kinematics of the flowComment: 11 pages, 4 figures (minor corrections and improvements

Career perceptions of undergraduate tourism students: A case study in Turkey

Cataloged from PDF version of article.The characteristics of tourism employment and careers have been widely documented. Although the development of the tourism industry can create new employment opportunities, it is often criticised for providing primarily low-skilled and low-paying jobs. If today's students are to become the effective practitioners of tomorrow, it is fundamental to understand their perceptions of tourism employment. This paper focuses on a sample of 450 Turkish students studying tourism at university level in order to analyse their perceptions towards tourism careers. The results showed that, overall, the respondents' perceptions are neither favourable nor unfavourable. The findings also indicated that: willingness to study tourism; willingness to work in tourism after graduation; and work experience; are important factors in shaping their image of tourism careers

Atrial conduction velocity mapping: clinical tools, algorithms and approaches for understanding the arrhythmogenic substrate

Characterizing patient-specific atrial conduction properties is important for understanding arrhythmia drivers, for predicting potential arrhythmia pathways, and for personalising treatment approaches. One metric that characterizes the health of the myocardial substrate is atrial conduction velocity, which describes the speed and direction of propagation of the electrical wavefront through the myocardium. Atrial conduction velocity mapping algorithms are under continuous development in research laboratories and in industry. In this review article, we give a broad overview of different categories of currently published methods for calculating CV, and give insight into their different advantages and disadvantages overall. We classify techniques into local, global, and inverse methods, and discuss these techniques with respect to their faithfulness to the biophysics, incorporation of uncertainty quantification, and their ability to take account of the atrial manifold

Distâncias e Proximidades entre Neopentecostalismo e Religiões Afro-Brasileiras: A Constituição Social do Sentido

As interações entre neopentecostalismo e religiões afro-brasileiras são abordadas nestetexto numa perspectiva de análise da constituição social do sentido em cada um destessistemas religiosos e na sua relação recíproca. A presença do cristianismo no continenteafricano ainda no final do século XV e principalmente nos séculos XVI e XVII jádemonstrava certa aproximação das tradições religiosas africanas com o cristianismo.De fato, embora os africanos e os europeus tivessem sistemas religiosos diferentes e umconjunto distinto de revelações básicas, eles possuíam várias ideias em comum quepossibilitaram esta aproximação. Agora, um tipo de aproximação pode ser constatadono encontro entre o neopentecostalismo e as religiões afro-brasileiras

A Workflow for Probabilistic Calibration of Models of Left Atrial Electrophysiology

Atrial fibrillation is an increasingly common condition. Computational models that describe left atrial electrophysiology have the potential to be used to guide interventions such as catheter ablation. Calibration of these models to faithfully represent left atrial structure and function in a particular patient is challenging because electrophysiology observations obtained in the clinical setting are typically sparse and noisy, and can be difficult to register to a mesh obtained from imaging. Probabilistic approaches show promise as a way to obtain personalised models while taking account of noise, sparseness, and uncertainty. We have developed a workflow in which parameter fields are represented as Gaussian processes, and the posterior distribution is inferred using MCMC. Our workflow has been tested using synthetic data, generated from simulations where the spatial variation in model parameters is known, and we have shown that both features and parameters can be recovered from simulated sparse measurements

Anisotropic Cardiac Conduction.

Anisotropy is the property of directional dependence. In cardiac tissue, conduction velocity is anisotropic and its orientation is determined by myocyte direction. Cell shape and size, excitability, myocardial fibrosis, gap junction distribution and function are all considered to contribute to anisotropic conduction. In disease states, anisotropic conduction may be enhanced, and is implicated, in the genesis of pathological arrhythmias. The principal mechanism responsible for enhanced anisotropy in disease remains uncertain. Possible contributors include changes in cellular excitability, changes in gap junction distribution or function and cellular uncoupling through interstitial fibrosis. It has recently been demonstrated that myocyte orientation may be identified using diffusion tensor magnetic resonance imaging in explanted hearts, and multisite pacing protocols have been proposed to estimate myocyte orientation and anisotropic conduction in vivo. These tools have the potential to contribute to the understanding of the role of myocyte disarray and anisotropic conduction in arrhythmic states