Chronic sojourn in hypoxic environment results in the structural remodeling of peripheral pulmonary arteries and pulmonary hypertension. We hypothesize that the pathogenesis of changes in pulmonary vascular structure is related to the increase of radical production induced by lung tissue hypoxia. Hypoxia primes alveolar macrophages to produce more hydrogen peroxide. Furthermore, the increased release of oxygen radicals by other hypoxic lung cells cannot be excluded. Several recent reports demonstrate the oxidant damage of lungs exposed to chronic hypoxia. The production of nitric oxide is high in animals with hypoxic pulmonary hypertension and the serum concentration of nitrotyrosine (radical product of nitric oxide and superoxide interaction) is also increased in chronically hypoxic rats. Antioxidants were shown to be effective in the prevention of hypoxia induced pulmonary hypertension. We suppose that the mechanism by which the radicals stimulate of the vascular remodeling is due to their effect on the metabolism of vascular wall matrix proteins. Non-enzymatic protein alterations and/or activation of collagenolytic matrix metalloproteinases may also participate. The presence of low-molecular weight cleavage products of matrix proteins stimulates the mesenchymal proliferation in the wall of distal pulmonary arteries. Thickened and less compliant peripheral pulmonary vasculature is then more resistant to the blood flow and the hypoxic pulmonary hypertension is developed., J. Herget, J. Wilhelm, J. Novotná, A. Eckhardt, R. Vytášek, L. Mrázková, M. Ošťádal., and Obsahuje bibliografii
In this paper is proved a weighted inequality for Riesz potential similar to the classical one by D. Adams. Here the gain of integrability is not always algebraic, as in the classical case, but depends on the growth properties of a certain function measuring some local potential of the weight.
This paper presents a novel error-feedback practical solution for real-time implementation of nonlinear output regulation. Sufficient and necessary conditions for both state- and error-feedback output regulation have been established for linear and nonlinear systems several decades ago. In their most general form, these solutions require solving a set of nonlinear partial differential equations, which may be hard or even impossible to solve analytically. In recent years, a methodology for dynamic calculation of the mappings required for state-feedback regulation has been put forward; following the latter, an error-feedback extension is hereby provided which, when combined with design conditions in the form of linear matrix inequalities, becomes suitable for real-time setups. Real-time results are presented for a nonlinear twin rotor MIMO system. Issues concerning the implementation as well as the solutions adopted, are discussed.
The existence of a positive solution for the generalized predator-prey model for two species $$ \begin{gathered} \Delta u + u(a + g(u,v)) = 0\quad \mbox {in}\ \Omega ,\\ \Delta v + v(d + h(u,v)) = 0\quad \mbox {in} \ \Omega ,\\ u = v = 0\quad \mbox {on}\ \partial \Omega , \end{gathered} $$ are investigated. The techniques used in the paper are the elliptic theory, upper-lower solutions, maximum principles and spectrum estimates. The arguments also rely on some detailed properties of the solution of logistic equations.
The purpose of the present study was to examine the role of the T-786C endothelial nitric oxide synthase (eNOS) gene polymorphism on changes in renal hemodynamics and blood pressure due to Na+ loading. Twenty-eight older (63±1 years), moderately obese (39±2 % fat) hypertensives had th eir glomerular filtration rate (GFR), renal plasma flow (RPF), blood pressure (BP) and plasma nitric oxide (NOx) levels determined after eight days of low (20 mEq) and high (200 mEq) Na+ diets. The two Na+ diets were separated by a 1-week washout period. Subjects were genotyped for the eNOS-786 site and were grouped on whether they were homozygous or heterozygous for the C allele (TC+CC, n=13) or only homozygous for the T allele (TT, n=15). The TC+CC genotype group had a significantly greater increase in diastolic (P=0.021) and mean arterial (P=0.018) BP and a significant decline in both RPF (P=0.007) and GFR (P=0.029) compared to the TT genotype group with Na+ loading. Furthermore, Na+ loading resulted in a significant (P=0.036) increase in plasma NOx in the TT, but not in the TC+CC genotype group as well as a trend (P=0.051) for an increase in urine NOx in TC+CC, but not in the TT genotype group. The increase in BP during Na+ loading in older hypertensives was associated with the eNOS genotype and may be related to changes in renal hemodynamics due to changes in NO metabolism., D. R. Dengel, M. D. Brown, R. E. Ferrell, T. H. Reynolds, M. A. Supiano., and Obsahuje bibliografii a bibliografické odkazy
Th e article reads the Czech literary canon during the period from 1948 to 1989 not from a consciously feminist standpoint, but from a gender perspective. Following works of Michel Foucault, Judith Butler, and Wendy Brown, the article’s primary focus is on fi ction written by dissent and alternative writers, with an emphasis on their role in what the author calls “dispositives of silence,” consisting of the discursive emergence of silencing and the aff ective dimension of “injurious attachments.” Th e article holds that while the dissident and alternative literary scene’s opposition to the then-offi cial regime made the need for political opposition clearly visible to it, other issues, such as the drive towards gender equality, became invisible to it, which represents a case of injurious attachments. In the article’s interpretative part, it reads literary works by writers Iva Pekárková, Tereza Boučková, and Pavel Kohout as examples that illustrate the issue of injurious attachments. In the article’s fi nal part, it supplements its thesis on dissident and alternative literature of the 1948–1989 period with a brief sketch of the literary evolution during the period, and it presents an overview of fi ve major – and partly contradictory – tendencies that can be identifi ed in the four decades in question.
We obtain a principal topology and some related results. We also give some hints of possible applications. Some mathematical systems are both lattice and topological space. We show that a topology defined on the any bounded lattice is definable in terms of uninorms. Also, we see that these topologies satisfy the condition of the principal topology. These topologies can not be metrizable except for the discrete metric case. We show an equivalence relation on the class of uninorms on a bounded lattice based on equality of the topologies induced by uninorms.
In this survey we consider superlinear parabolic problems which possess both blowing-up and global solutions and we study a priori estimates of global solutions.
We present an approach for probabilistic contour prediction within the framework of an object tracking system. We combine level-set methods for image segmentation with optical flow estimations based on probability distribution functions (pdfs) calculated at each image position. Unlike most recent level-set methods that consider exclusively the sign of the level-set function to determine an object and its background, we introduce a novel interpretation of the value of the level-set function that reflects the confidence in the contour. To this end, in a sequence of consecutive images, the contour of an object is transformed according to the optical flow estimation and used as the initial object hypothesis in the following image. The values of the initial level-set function are set according to the optical flow pdfs and thus provide an opportunity to incorporate the uncertainties of the optical flow estimation in the object contour prediction.