Interindividual Age-Independent Differences in Human CX43 Impact Ventricular Arrhythmic Risk

Connexin 43 (CX43) is one of the major components of gap junctions, the structures responsible for the intercellular communication and transmission of the electrical impulse in the left ventricle. There is limited information on the histological changes of CX43 with age and their effect on electrophysiology, especially in humans. Here, we analyzed left ventricular biopsies from living donors starting at midlife to characterize age-related CX43 remodeling. We assessed its quantity, degree of lateralization, and spatial heterogeneity together with fibrotic deposition. We observed no significant age-related remodeling of CX43. Only spatial heterogeneity increased slightly with age, and this increase was better explained by biological age than by chronological age. Importantly, we found that CX43 features varied considerably among individuals in our population with no relevant relationship to age or fibrosis content, in contrast to animal species. We used our experimental results to feed computational models of human ventricular electrophysiology and to assess the effects of interindividual differences in specific features of CX43 and fibrosis on conduction velocity, action potential duration, and arrhythmogenicity. We found that larger amounts of fibrosis were associated with the highest arrhythmic risk, with this risk being increased when fibrosis deposition was combined with a reduction in CX43 amount and/or with an increase in CX43 spatial heterogeneity. These mechanisms underlying high arrhythmic risk in some individuals were not associated with age in our study population. In conclusion, our data rule out CX43 remodeling as an age-related arrhythmic substrate in the population beyond midlife, but highlight its potential as a proarrhythmic factor at the individual level, especially when combined with increased fibrosis.

Fractal Interpolation Functions: A Short Survey

The object of this short survey is to revive interest in the technique of fractal interpolation. In order to attract the attention of numerical analysts, or rather scientific community of researchers applying various approximation techniques, the article is interspersed with comparison of fractal interpolation functions and diverse conventional interpolation schemes. There are multitudes of interpolation methods using several families of functions: polynomial, exponential, rational, trigonometric and splines to name a few. But it should be noted that all these conventional nonrecursive methods produce interpolants that are differentiable a number of times except possibly at a finite set of points. One of the goals of the paper is the definition of interpolants which are not smooth, and likely they are nowhere differentiable. They are defined by means of an appropriate iterated function system. Their appearance fills the gap of non-smooth methods in the field of approximation. Another interesting topic is that, if one chooses the elements of the iterated function system suitably, the resulting fractal curve may be close to classical mathematical functions like polynomials, exponentials, etc. The authors review many results obtained in this field so far, although the article does not claim any completeness. Theory as well as applications concerning this new topic published in the last decade are discussed. The one dimensional case is only considered.

Hispanic Women＇s Presence in the Actual U.S. Congress

The Hispanic population of the United States has become, in recent times, into a powerful electoral force whose vote is historically oriented towards the Democratic Party of the incumbent US President Barack H. Obama. Obviously, this growing electoral strength is reflected into its political presence in the American life that has been accomplished with their numeric inclusion in the US Congress. Although in the recent decades several studies have arisen on the status of the Hispanic community in the United States from both sides of the Atlantic, these have been primarily focused on casuistic, demographic, developmental or educational aspects. But only a few of them, if any, has focused exclusively on the numerical and symbolical representation of the community in the political arena, and more specifically into the main legislative body of the country, the US Congress. And therein it lays the purpose of this article. We intend to investigate not only the historical presence of Hispanic legislators in Congress but also and especially their political influence in the current U.S. Congress. Finally, and prior to the conclusions drawn throughout the paper, we will analyze the political influence of the Hispanic congresswomen in the current 114th Congress. As we will be breaking down, this group has been changing gradually from a poor oppressed minority into one of the most dynamic groups of the country, introduced at all levels of government.

On a Variant of Giuga Numbers

In this paper, we characterize the odd positive integers n satisfying the congruence ∑j=1^n-1 j n-1/2 We show that the set of such positive integers has an asymptotic densitywhich turns out to be slightly larger than 3/8.