Energetic Consistency and Momentum Conservation in the Gyrokinetic Description of Tokamak Plasmas

Gyrokinetic field theory is addressed in the context of a general Hamiltonian. The background magnetic geometry is static and axisymmetric, and all dependence of the Lagrangian upon dynamical variables is in the Hamiltonian or in free field terms. Equations for the fields are given by functional derivatives. The symmetry through the Hamiltonian with time and toroidal angle invariance of the geometry lead to energy and toroidal momentum conservation. In various levels of ordering against fluctuation amplitude, energetic consistency is exact. The role of this in underpinning of conservation laws is emphasised. Local transport equations for the vorticity, toroidal momentum, and energy are derived. In particular, the momentum equation is shown for any form of Hamiltonian to be well behaved and to relax to its magnetohydrodynamic (MHD) form when long wavelength approximations are taken in the Hamiltonian. Several currently used forms, those which form the basis of most global simulations, are shown to be well defined within the gyrokinetic field theory and energetic consistency.Comment: RevTeX 4, 47 pages, no figures, revised version updated following referee comments (discussion more strictly correct/consistent, 4 references added, results unchanged as they depend on consistency of the theory), resubmitted to Physics of Plasma

Modelling granular soil behaviour using a physics engine

A physics engine is a software library used in the film and computer games industries to realistically animate a physical system. In this paper it is shown that particulate media can be faithfully modelled using a rigid body physics engine, thereby providing a viable alternative to the discrete element method codes currently used in the field of geomechanics. An overview of the simulation method implemented in the widely used Box2D physics engine is provided, and it is shown that this tool can successfully capture the critical state response of granular media, using particles modelled as randomly shaped polygons

Taxa de natalidade no rebanho bovino no Pantanal: nutrição, sanidade e genética.

No século XVIII com a decadência das lavras auríferas de Cuiabá, a população local passou a desenvolver a agricultura no vale do Guaporé e a pecuária na planície pantaneira, região salubre e com pastagens nativas de melhor qualidade para a criação de gado. No sentido norte-sul, todo o Pantanal foi ocupado pela pecuária de corte extensiva promovendo até as primeiras décadas do último século a indústria do charque e de outros subprodutos como crina, couro e extratos. A criação de gado floresceu tanto que na década de 40 representava 6% do rebanho nacional e 90% do então estado de Mato Grosso. Com o desenvolvimento da pecuária no Triângulo Mineiro e noroeste de São Paulo, o gado do Pantanal passou a ser comercializado "em pé" para aquelas regiões impulsionado, posteriormente, com a construção da estrada de ferro Noroeste do Brasil. A taxa de natalidade no rebanho nelorado em pastagens nativas no Pantanal está em torno de 55%, mas varia de 40% a 60% em função da proporção de fitofisionomias e do grau de propensão à inundação das invernadas. Períodos de seca melhoram o índice de natalidade em todo o Pantanal pela disponibilização de mais pastagens de melhor qualidade nas áreas baixas sujeitas a inundação. Outra característica da região é a idade tardia na primeira cria com aproximadamente quatro anos (Tullio, 1986; Pott et al., 1987a; Abreu et al., 2000). O objetivo deste trabalho é revisar os trabalhos publicados sobre o assunto.bitstream/item/79415/1/COT29.pd

Axisymmetric plasma equilibrium in gravitational and magnetic fields

Plasma equilibria in gravitational and open-ended magnetic fields are considered for the case of topologically disconnected regions of the magnetic flux surfaces where plasma occupies just one of these regions. Special dependences of the plasma temperature and density on the magnetic flux are used which allow the solution of the Grad–Shafranov equation in a separable form permitting analytic treatment. It is found that plasma pressure tends to play the dominant role in the setting the shape of magnetic field equilibrium, while a strong gravitational force localizes the plasma density to a thin disc centered at the equatorial plane

Reduction and approximation in gyrokinetics

The gyrokinetics formulation of plasmas in strong magnetic fields aims at the elimination of the angle associated with the Larmor rotation of charged particles around the magnetic field lines. In a perturbative treatment or as a time-averaging procedure, gyrokinetics is in general an approximation to the true dynamics. Here we discuss the conditions under which gyrokinetics is either an approximation or an exact operation in the framework of reduction of dynamical systems with symmetryComment: 15 pages late

Should we perform multiparametric magnetic resonance imaging of the bladder before transurethral resection of bladder? Time to reconsider the rules

We would like to congratulate Ueno and colleagues [1] on their paper on diagnostic accuracy and interobserver agreement for the new Vesical Imaging-Reporting and Data System (VI-RADS) [2] for muscle-invasive bladder cancer (MIBC) in this issue of European Urology. Their report on 74 patients who underwent multiparametric magnetic resonance imaging (mpMRI) before transurethral resection of bladder tumor (TURBT) raises great interest in the RADS (Reporting and Data Systems) era. They address the questions of reproducibility and diagnostic performance of mpMRI in the setting of bladder ca (BC), in which potential applications of this imaging technique have seen constant growth in the past decades without a definitive role having been identified

Efeito acaricida in vitro de extratos de plantas do Pantanal no carrapato de bovinos, Rhipicephalus (Boophilus) microplus.

Estudou-se a ação acaricida dos extratos brutos etanólicos de 14 plantas do Pantanal sobre fêmeas ingurgitadas do carrapato-do-boi. Os bioensaios foram realizados em triplicatas pelo método de imersão das teleóginas e estimadas a produção de ovos, a eclodibilidade e a eficácia dos extratos. Extratos do lenho da raiz e da casca da raiz de Annona dioica, da raiz e da casca do caule de Simarouba versicolor, da raiz de Annona cornifolia e de Duguetia furfuracea tiveram atividade acaricida entre 50% e 100% e resposta dose-dependente. Extratos de Dimorphandra mollis, Magonia pubescens, Protium heptaphyllum, Hyptis crenata, Sebastiana hispida, Aspidosperma australe, Senna occidentalis e de Elyonurus muticus mostraram atividade acaricida baixa ou ausente (0% a 10%). Extratos da parte aérea de A. cornifolia, da planta inteira de Croton glandulosus e da casca do caule de Stryphnodendron obovatum mostraram atividade acaricida intermediária (10% a 20%). A alta atividade acaricida observada nos extratos de A. dioica, A. cornifolia e D. furfuracea indica ação de acetogeninas, moléculas naturais com várias atividades farmacológicas já descritas e presentes, principalmente, nas plantas da família Annonaceae.bitstream/CNPGC-2010/13215/1/BP26.pd

Atualização sobre o controle estratégico do carrapato-do-boi.

Detecção da resistência. Classe dos carrapaticidas. Ciclo biológico do carrapato R. microplus. Controle estratégico. Cuidados no controle.bitstream/CNPGC-2010/13274/1/COT123.pd

Binding threshold for the Pauli-Fierz operator

For the Pauli-Fierz operator with a short range potential we study the binding threshold as a function of the fine structure constant $\alpha$ and show that it converges to the binding threshold for the Schr\"odinger operator in the small $\alpha$ limit