Na/K pump regulation of cardiac repolarization: Insights from a systems biology approach

The sodium-potassium pump is widely recognized as the principal mechanism for active ion transport across the cellular membrane of cardiac tissue, being responsible for the creation and maintenance of the transarcolemmal sodium and potassium gradients, crucial for cardiac cell electrophysiology. Importantly, sodium-potassium pump activity is impaired in a number of major diseased conditions, including ischemia and heart failure. However, its subtle ways of action on cardiac electrophysiology, both directly through its electrogenic nature and indirectly via the regulation of cell homeostasis, make it hard to predict the electrophysiological consequences of reduced sodium-potassium pump activity in cardiac repolarization. In this review, we discuss how recent studies adopting the Systems Biology approach, through the integration of experimental and modeling methodologies, have identified the sodium-potassium pump as one of the most\ud important ionic mechanisms in regulating key properties of cardiac repolarization and its rate-dependence, from subcellular to whole organ levels. These include the role of the pump in the biphasic modulation of cellular repolarization and refractoriness, the rate control of intracellular sodium and calcium dynamics and therefore of the adaptation of repolarization to changes in heart rate, as well as its importance in regulating pro-arrhythmic substrates through modulation of dispersion of repolarization and restitution. Theoretical findings are consistent across a variety of cell types and species including human, and widely in agreement with experimental findings. The novel insights and hypotheses on the role of the pump in cardiac electrophysiology obtained through this integrative approach could eventually lead to novel therapeutic and diagnostic strategies

Type-4 spinors: transmuting from Elko to single-helicity spinors

In this communication we briefly report an unexpected theoretical discovery which emerge from the mapping of Elko mass-dimension-one spinors into single helicity spinors. Such procedure unveils a class of spinor which is classified as type-4 spinor field within Lounesto classification. In this paper we explore the underlying physical and mathematical contents of the type-4 spinor.Comment: 9 pages, 0 figure

On the bilinear covariants associated to mass dimension one spinors

In this paper we approach the issue of Clifford algebra basis deformation, allowing for bilinear covariants associated to Elko spinors which satisfy the Fierz-Pauli-Kofink identities. We present a complete analysis of covariance, taking into account the involved dual structure associated to Elko. Moreover, the possible generalizations to the recently presented new dual structure are performed.Comment: 9 pages, 0 figure

Gerenciamento de riscos das nanotecnologias: aplicações do método GMP-RAM ao ciclo PDCA.

Resumo: Apesar dos nanomateriais já estarem presentes em grandes linhas de Pesquisa e Desenvolvimento e à disposição dos consumidores, ainda não existem metodologias consolidadas para o Gerenciamento de Risco associado ao ciclo de vida e ao uso intensivo desses novos materiais. Neste cenário, o presente trabalho propõe o emprego e adequação do Método GMP-RAM para o caso das nanotecnologias em diversas dimensões, associados ao ciclo PDCA para a avaliação, mitigação e minimização do risco encontrado. Dessa forma, pode-se concluir que as duas metodologias associadas são favoráveis para a quantificação do risco e tomadas de decisão por meio do plano de ação proposto, caso a caso

Emprego e adaptação do método GMP-RAM para avaliação dos riscos das nanotecnologias.

Resumo: A Nanotecnologia está baseada na crescente capacidade da tecnologia moderna em manipular átomos e partículas na nanoescala para criar novos materiais e desenvolver novos produtos e processos. Ela promete grandes avanços nas mais diversas áreas de atuação, desde a Medicina à Engenharia de Materiais. Apesar dos materiais nanoestruturados apresentarem propriedades físicas diferentes do seu correspondente convencional, ainda não há metodologias para avaliação de riscos direcionadas ao uso intensivo desses novos materiais e substâncias químicas. Neste cenário, o presente trabalho propõe o emprego e adequação de uma metodologia comumente empregada para a avaliação de risco de transgênicos para o caso das nanotecnologias. O método GMP-RAM já foi empregado com sucesso para o caso do mamão geneticamente modificado para resistência ao vírus da mancha anelar. Abstract: Nanotechnology is based on the increasing power of modern technology to manipulate atoms and particles at the nanoscale to create new materials and develop new products and processes. It promises great advances in several areas of expertise, from medicine to Materials Engineering. Although engineered nanomaterials present different physical properties of its corresponding conventional, there are no methodologies for risk assessment to determine the intensive use of these new materials and chemicals. In this scenario, this study proposes the use and adequacy of a methodology commonly used for the risk assessment of transgenic for the case of nanotechnology. The GMP-RAM Method has already been used successfully to perform the case study of the papaya genetically modified for resistance to the ringspot virus.bitstream/item/52419/1/boletim-62.pd

Observations of solar scattering polarization at high spatial resolution

The weak, turbulent magnetic fields that supposedly permeate most of the solar photosphere are difficult to observe, because the Zeeman effect is virtually blind to them. The Hanle effect, acting on the scattering polarization in suitable lines, can in principle be used as a diagnostic for these fields. However, the prediction that the majority of the weak, turbulent field resides in intergranular lanes also poses significant challenges to scattering polarization observations because high spatial resolution is usually difficult to attain. We aim to measure the difference in scattering polarization between granules and intergranules. We present the respective center-to-limb variations, which may serve as input for future models. We perform full Stokes filter polarimetry at different solar limb positions with the CN band filter of the Hinode-SOT Broadband Filter Imager, which represents the first scattering polarization observations with sufficient spatial resolution to discern the granulation. Hinode-SOT offers unprecedented spatial resolution in combination with high polarimetric sensitivity. The CN band is known to have a significant scattering polarization signal, and is sensitive to the Hanle effect. We extend the instrumental polarization calibration routine to the observing wavelength, and correct for various systematic effects. The scattering polarization for granules (i.e., regions brighter than the median intensity of non-magnetic pixels) is significantly larger than for intergranules. We derive that the intergranules (i.e., the remaining non-magnetic pixels) exhibit (9.8 \pm 3.0)% less scattering polarization for 0.2<u<0.3, although systematic effects cannot be completely excluded. These observations constrain MHD models in combination with (polarized) radiative transfer in terms of CN band line formation, radiation anisotropy, and magnetic fields.Comment: Accepted for publication in A&

Relato de Rhizoctonia solani AG-4 HG I em crisântemo (Papiro Branco e Amarelo) e R. solani AG-4 HG III em gipsófila no Estado de São Paulo, Brasil, e sua patogenicidade cruzada.

Resumo: Atualmente, grupamento de anastomose (AG) de Rhizoctonia sp. em crisântemo e ocorrência deste fungo em gipsófila ainda não foram realizados no Brasil. Assim, realizou-se teste de patogenicidade normal e cruzada e sequenciamento da região ITS-5.8S rDNA para identificar o AG de isolado obtido de plantas de crisântemo (Papiro branco) e de gipsófila, ambas originárias de Holambra/São Paulo,Brasil. Após os testes, relata-se pela primeira vez a ocorrência de R. solani AG-4 HGI em crisântemo (Papiro Branco e Amarelo) e R. solani AG-4 HG III em gipsófila, no estado de São Paulo,Brasil, e também a sua patogenicidade cruzada. Abstract: Currently, anastomosis groups (AG) of Rhizoctonia sp. on chrysanthemum and occurrence of this fungus on gypsophila have not been reported in Brazil. However, in the present study, normal and cross pathogenicity and sequencing of ITS-5.8S rDNA regions were used to confirm the AG of isolate of Rhizoctonia sp. obtained from chrysanthemum (White Papyrus) and from gypsophila plants cultivated in Holambra / São Paulo, Brazil. After these tests, it was confirmed the report of Rhizoctonia solani AG-4 HG I on chrysanthemum (White and Yellow Papyrus) and R. solani AG-4 HG III on gypsophila in the São Paulo state, Brazil, and also their cross pathogenicity

Continuous adjoint approach for the spalart-allmaras model in aerodynamic optimization

In this paper, the continuous adjoint method to compute shape sensitivities in aerodynamic design with turbulence modeling is described and developed. The focus is on compressible flows described by the Reynolds-averaged Navier-Stokes equations and the classical Spalart-Allmaras model for turbulence. Turbulence modeling usually requires, in particular, computation of the distance to the surface. Here, this distance is incorporated to the system as a new variable, solving the Eikonal equation. The accuracy of the sensitivity derivatives obtained with the complete turbulent approach is assessed by comparison with finite difference computations and the classical continuous adjoint with frozen viscosity, showing substantial improvements in the convergence properties of the method and in the quality of the obtained gradients. The validity of the overall methodology is illustrated with several design examples, including the optimization of three-dimensional geometries in combination with advanced freeform techniques for mesh deformation