Genetic and Epigenetic Regulation in Nonalcoholic Fatty Liver Disease (NAFLD)

Genetics and epigenetics play a key role in the development of several diseases, including nonalcoholic fatty liver disease (NAFLD). Family studies demonstrate that first degree relatives of patients with NAFLD are at a much higher risk of the disease than the general population. The development of the Genome Wide Association Study (GWAS) technology has allowed the identification of numerous genetic polymorphisms involved in the evolution of diseases (e.g., PNPLA3, MBOAT7). On the other hand, epigenetic changes interact with inherited risk factors to determine an individual’s susceptibility to NAFLD. Modifications of the histones amino-terminal ends are key factors in the maintenance of chromatin structure and gene expression (cAMP-responsive element binding protein H (CREBH) or SIRT1). Activation of SIRT1 showed potential against the physiological mechanisms related to NAFLD. Abnormal DNA methylation represents a starting point for cancer development in NAFLD patients. Besides, the evaluation of circulating miRNA profiles represents a promising approach to assess and non-invasively monitor liver disease severity. To date, there is no approved pharmacologic therapy for NAFLD and the current treatment remains weight loss with lifestyle modification and exercise. In this review, the status of research into relevant genetic and epigenetic modifiers of NAFLD progression will be discusse

Busca de ensaios clínicos randomizados e revisões sistemáticas sobre exercício físico. Um estudo descritivo

CONTEXT AND OBJECTIVE: The current paradigm of science is to accumulate as much research data as possible, with less thought given to navigation or synthesis of the resulting mass, which hampers locating and using the research. The aim here was to describe the number of randomized controlled trials (RCTs) and systematic reviews (SRs) focusing on exercise, and their journal sources, that have been indexed in PubMed over time. DESIGN AND SETTING: Descriptive study conducted at Bond University, Australia. METHOD: To find RCTs, a search was conducted in PubMed Clinical Queries, using the category "Therapy" and the Medical Subject Headings (MeSH) term "Exercise". To find SRs, a search was conducted in PubMed Clinical Queries, using the category "Therapy", the MeSH term "Exercise" and various methodological filters. RESULTS: Up until 2011, 9,354 RCTs about exercise were published in 1,250 journals and 1,262 SRs in 513 journals. Journals in the area of Sports Science published the greatest number of RCTs and journals categorized as belonging to "Other health professions" area (for example nursing or psychology) published the greatest number of SRs. The Cochrane Database of Systematic Reviews was the principal source for SRs, with 9.8% of the total, while the Journal of Strength and Conditioning Research and Medicine &amp; Science in Sports &amp; Exercise published 4.4% and 5.0% of the RCTs, respectively. CONCLUSIONS: The rapid growth and resulting scatter of RCTs and SRs on exercise presents challenges for locating and using this research. Solutions for this issue need to be considered.</jats:p

Exercise for acute respiratory infections

No abstract available

ADI-FDTD modeling of Tellegen media

The magnetoelectric coupling that appears in the constitutive relations of Tellegen media makes formulating unconditionally stable finite-difference time-domain (FDTD) extensions a challenging problem. In this letter, we present an alternating-direction implicit (ADI)-FDTD approach for modeling transient wave propagation in Tellegen media. In the proposed formulation, the discretization of the governing equations is performed introducing weighted average parameters. The numerical features are then carefully examined and the weighted discretization parameters conveniently chosen to yield an unconditionally stable scheme. Moreover, the resulting approach presents second-order accuracy and preserves the tridiagonal structure of the data matrices. Finally, the numerical dispersion relation is given in a closed form. The new method has been validated by means of numerical experiments and has shown good agreement.This work was supported by the Spanish Ministerio de Economía y Competitividad under Projects TEC2010-21496-C03-01 and CONSOLIDER CSD2008-00066 and the subprogram Ramón y Cajal RYC-2010-06922

Accuracy limitations of the locally one-dimensional FDTD technique

While the alternating-direction implicit finite-difference time-domain (ADI-FDTD) method preserves the second-order temporal accuracy of the conventional FDTD technique, the locally one-dimensional (LOD)-FDTD method exhibits a first-order in time splitting error. Despite this difference, the numerical dispersion analyses of these methods reveal that both present similar accuracy properties. For this reason, the characteristic noncommutativity error of the LOD-FDTD scheme has not received much attention. In this letter, we determine the closed form of the local truncation error for the 3D-LOD-FDTD scheme. We find that it presents error terms that depend on the time-step size multiplied by the spatial derivatives of the fields. Numerical results confirm that these terms become a significant source of error that is not revealed in the dispersion analyses.This work was supported by the Spanish Ministerio de Economía y Competitividad under projects TEC2010-21496-C03-01 and CONSOLIDER CSD2008-00066 and the subprogram Ramón y Cajal RYC-2010-06922

On the behavior of the LOD-FDTD method at dielectric interfaces

The electric field computed by the locally 1-D finite-difference time-domain (FDTD) method at dielectric interfaces is investigated. To this end, two comprehensive problems are considered, namely a dielectric step in a rectangular waveguide and a dielectric-loaded metallic cavity. We found that, in both problems, the electric field patterns exhibit an unexpected phase shift at the dielectric interface. By contrast, the alternating-direction implicit FDTD method does not present this unphysical behavior.This work was supported in part by the Spanish Government (MINECO) and the European Commission (ERDF) under Research Projects TEC2014-55463-C3-2-P and TEC2014-55463-C3-3-P

Analysis of homogeneous waveguides via the meshless radial basis function-generated-finite-difference method

The radial basis function generatedfinite difference (RBFFD) method is applied to the analysis of homogenous waveguides. To this end, the Helmholtz equation and the boundary conditions are collocated on the waveguide cross section. At each collocation node, derivatives are locally approximated by RBFFD formulas based on polyharmonic splines supplemented with highdegree polynomials. As a result, a sparse matrix eigenvalue problem is obtained which allows cutoff wavenumbers and axial fields to be calculated. To illustrate the accuracy of the method, we consider a semicircular and an eccentric circular waveguides.This work was supported in part by the Spanish Government (MCIU/AEI) and the European Commission (FEDER, UE) under Research Projects PGC2018-098350-B-C21and PGC2018-098350-B-C22

Pseudospectral frequency-domain analysis of rectangular waveguides filled by dielectrics whose permittivity varies continuously along the broad dimension

The calculation of dispersion diagrams and field patterns of metallic rectangular waveguides filled with an inhomogeneous dielectric whose permittivity varies continuously along the broad size of the guide is considered. In general, this problem has no exact solution, thus numerical techniques should be used. In this article, the pseudospectral frequency-domain (PSFD) method is proposed to address the problem. Starting from the Helmholtz equation, a matrix eigenvalue problem is obtained by applying the collocation technique with Chebyshev polynomials as basis functions. The results obtained are compared with those calculated by the conventional finite-difference frequency-domain method showing that the PSFD technique provides an excellent accuracy.This work was supported in part by the Spanish Government (MCIU/AEI) and the European Commission (FEDER, UE) under Research Projects PGC2018-098350-B-C21 and PGC2018-098350-B-C22

Numerical dispersion relation for the 2D LOD-FDTD method in lossy media

A closed-form expression is derived for the numerical dispersion relation of the 2-D locally one-dimensional finite-difference time-domain (LOD-FDTD) method in lossy media. In contrast to the lossless formulation, we found that transverse-electric (TEz ) and transverse-magnetic (TMz ) waves in lossy media exhibit different numerical dispersion relations. Moreover, when the material relaxation-time constant is not well resolved by the integration time-step, the TMz case shows much worse accuracy than the TEz case. To remove this limitation, a split-field LOD-FDTD formulation for TMz waves is then considered, which exhibits the same dispersion relation as the LOD-FDTD method for TEz waves. The validity of the theoretical results is illustrated through numerical simulations.This work was supported in part by the Spanish Government (MINECO) and the European Commission (ERDF) under Research Projects TEC2014-55463-C3-2-P and TEC2014-55463-C3-3-P

A unified view of DI- and ETD-FDTD methods for drude media

A unified view of direct-integration (DI) and exponential-time-differencing (ETD) methods to incorporate Drude media, such as isotropic plasma and microwave graphene, into finite-difference time-domain (FDTD) simulators is provided. To this end, the Drude constitutive relation is expressed in integral form and the DI integrators are obtained by applying quadrature rules. Analogously, the ETD integrators are obtained by starting from the variation of constants formula and applying the same quadrature rules as in the DI case. This approach allows one to directly compare the two families of methods. In addition, the accuracy of each integrator is discussed and the stability condition of the resulting FDTD schemes is derived in exact closed form by applying the von Neumann method.This work was supported in part by the I+D+i Projects under Grant PGC2018-098350-B-C21 and Grant PGC2018-098350-B-C22 and in part by MCIN/AEI/10.13039/501100011033/FEDER “Una manera de hacer Europa.