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.
This study was directed to use the genetically developed isoprenaline-sensitive (S), isoprenaline-resistant (R) and spontaneous hypertensive rats (SHR) as standard diseased animal models for in vitro liver function evaluation of drug biotransformation. Hepatic hexobarbital hydroxylase and glutathione transferase (GST) were evaluated by using hexobarbital and l-chloro-2,4-dinitrobenzene (CDNB) as substrates, at concentrations of 0.21 mmol/l and 1 mmol/l, respectively. The assay was conducted by using isolated hepatocytes in suspension and hepatocytes in a bioreactor configuration. The data demonstrate that there are certain cellular pharmacokinetic differénces in hexobarbital hydroxylase and GST activities in hepatocytes obtained from Wistar, SHR, R and S strains which can be better demonstrated, when using the model of perfused and immobilized hepatocytes.
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
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.
The aim of this paper is to propose a new approach to probability density function (PDF) estimation which is based on the fuzzy transform (F-transform) introduced by Perfilieva in \cite{Perfilieva:FSS06}. Firstly, a smoothing filter based on the combination of the discrete direct and continuous inverse F-transform is introduced and some of the basic properties are investigated. Next, an alternative approach to PDF estimation based on the proposed smoothing filter is established and compared with the most used method of Parzen windows. Such an approach can be of a great value mainly when dealing with financial data, i. e. large samples of observations.