Various mathematical models have been developed to describe the transmission of malaria disease. The purpose this study was modify an existing model disease by using a CTMC stochastic model. investigation focused on transition probability, basic reproduction number (R0), outbreak expected time required reach disease-free equilibrium, and quasi-stationary probability distribution. population sys...

In this paper, an ordinary differential equation model of HIV infection of CD4 T-cells with saturated reverse function is studied. We prove that if the basic reproduction number R0 < 1, the virus-free equilibrium is locally asymptotically stable. And there will exhibit backward bifurcation when R0 < 1. If R0 > 1, some feasibly sufficient conditions are obtained for the global asymptotic stabili...

A more realistic two-stage model for binge drinking problem is introduced, where the youths with alcohol problems are divided into those who admit the problem and those who do not admit it. We also consider the direct transfer from the class of susceptible individuals towards the class of admitting drinkers. Mathematical analyses establish that the global dynamics of the model are determined by...

We study the combined effects of seasonal trends and diseases on the extinction and persistence of discretely reproducing populations. We introduce the epidemic threshold parameter, R0, for predicting disease dynamics in periodic environments. Typically, in periodic environments, R0 > 1 implies disease persistence on a cyclic attractor, while R0 < 1 implies disease extinction. We also explore t...

Let P be a set of n points in three dimensions. The 2-center problem for P is to find two closed congruent balls with smallest radius which cover P . We present a randomized algorithm for solving the problem in O ( 1 (1−r∗/r0)3n 2 log n ) expected time, where r∗ is the common radius of the optimal solution balls and r0 is the radius of the smallest enclosing ball of P . This improves the naive ...

A SEIR model with vaccination, recruitment and natural death, as well as disease-caused death is studied. A threshold R0 is identified which determines the global dynamics of the system and the outcome of the disease; if R0 ≤ 1, the infected individuals of the population disappears so the disease dies out, while if R0 > 1, under a suitable restriction on the parameters, the infected individuals...

This paper presents a new approach to the tracking of regions in an image sequence. Unlike most other methods, the proposed approach can handle topology changes, i.e., regions may split or merge. This flexibility is naturally embedded into a partial differential equation that solves a minimum description length (MDL) estimation problem. The basic estimation criterion consists of only two terms:...

Based on dramatic observations of the cosmic microwave background radiation with WMAP and of Type Ia supernovae with the Hubble Space Telescope and ground-based facilities, it is now generally believed that the Universe’s expansion is accelerating. Within the context of standard cosmology, this type of evolution leads to the supposition that the Universe must contain a third ‘dark’ component of...

A classical result by Buchdahl [6] shows that for static solutions of the spherically symmetric Einstein-matter system, the total ADM mass M and the area radius R of the boundary of the body, obey the inequality 2M/R ≤ 8/9. The proof of this inequality rests on the hypotheses that the energy density is non-increasing outwards and that the pressure is isotropic. In this work neither of Buchdahl’...

BACKGROUND Primary treatment of patients with advanced epithelial ovarian cancer consists of chemotherapy either before (neoadjuvant chemotherapy, NACT) or after primary surgery (adjuvant chemotherapy). The goal of primary treatment is no residual disease after surgery (R0 resection) what is associated with an improvement in survival of patients. There is, however, no evidence of survival benef...