The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Daniel Campos - One of the best experts on this subject based on the ideXlab platform.

  • Population extinction and survival in a Hostile Environment.
    Physical Review E, 2008
    Co-Authors: Vicenç Méndez, Daniel Campos
    Abstract:

    We study the conditions for extinction and survival of populations living in a patch surrounded by a Hostile Environment. We find analytic expressions for the steady states when population dynamics is described by diffusion and reaction is driven by compensation, depensation, or critical depensation growths. The role of initial population density is studied, and the complete bifurcation diagrams are constructed and validated numerically for the three cases studied.

Vicenç Méndez - One of the best experts on this subject based on the ideXlab platform.

  • Population extinction and survival in a Hostile Environment.
    Physical Review E, 2008
    Co-Authors: Vicenç Méndez, Daniel Campos
    Abstract:

    We study the conditions for extinction and survival of populations living in a patch surrounded by a Hostile Environment. We find analytic expressions for the steady states when population dynamics is described by diffusion and reaction is driven by compensation, depensation, or critical depensation growths. The role of initial population density is studied, and the complete bifurcation diagrams are constructed and validated numerically for the three cases studied.

Franzx Beck - One of the best experts on this subject based on the ideXlab platform.

  • cell survival in the Hostile Environment of the renal medulla
    Annual Review of Physiology, 2005
    Co-Authors: Wolfgang Neuhofer, Franzx Beck
    Abstract:

    ▪ Abstract The countercurrent system in the medulla of the mammalian kidney provides the basis for the production of urine of widely varying osmolalities, but necessarily entails extreme conditions for medullary cells, i.e., high concentrations of solutes (mainly NaCl and urea) in antidiuresis, massive changes in extracellular solute concentrations during the transitions from antidiuresis to diuresis and vice versa, and low oxygen tension. The strategies used by medullary cells to survive in this Hostile milieu include accumulation of organic osmolytes and heat shock proteins, the extensive use of the glycolysis for energy production, and a well-orchestrated network of signaling pathways coordinating medullary circulation and tubular work.

Calin Belta - One of the best experts on this subject based on the ideXlab platform.

  • probabilistically safe vehicle control in a Hostile Environment
    arXiv: Systems and Control, 2011
    Co-Authors: Igor Cizelj, Xu Chu Ding, Morteza Lahijanian, Alessandro Pinto, Calin Belta
    Abstract:

    In this paper we present an approach to control a vehicle in a Hostile Environment with static obstacles and moving adversaries. The vehicle is required to satisfy a mission objective expressed as a temporal logic specification over a set of properties satisfied at regions of a partitioned Environment. We model the movements of adversaries in between regions of the Environment as Poisson processes. Furthermore, we assume that the time it takes for the vehicle to traverse in between two facets of each region is exponentially distributed, and we obtain the rate of this exponential distribution from a simulator of the Environment. We capture the motion of the vehicle and the vehicle updates of adversaries distributions as a Markov Decision Process. Using tools in Probabilistic Computational Tree Logic, we find a control strategy for the vehicle that maximizes the probability of accomplishing the mission objective. We demonstrate our approach with illustrative case studies.

  • probabilistically safe vehicle control in a Hostile Environment
    IFAC Proceedings Volumes, 2011
    Co-Authors: Igor Cizelj, Xu Chu Ding, Morteza Lahijanian, Alessandro Pinto, Calin Belta
    Abstract:

    Abstract In this paper we present an approach to control a vehicle in a Hostile Environment with static obstacles and moving adversaries. The vehicle is required to satisfy a mission objective expressed as a temporal logic specification over a set of properties satisfied at regions of a partitioned Environment. We model the movements of adversaries in between regions of the Environment as Poisson processes. Furthermore, we assume that the time it takes for the vehicle to traverse in between two facets of a region is exponentially distributed, and we obtain the rate of this exponential distribution from a simulator of the Environment. We capture the motion of the vehicle and the vehicle updates of adversaries distributions as a Markov Decision Process. Using tools in Probabilistic Computational Tree Logic, we find a control strategy for the vehicle that maximizes the probability of accomplishing the mission objective. We demonstrate our approach with illustrative case studies.

Régine Marchand - One of the best experts on this subject based on the ideXlab platform.

  • Growth of a Population of Bacteria in a Dynamical Hostile Environment
    Advances in Applied Probability, 2014
    Co-Authors: Olivier Garet, Régine Marchand
    Abstract:

    We study the growth of a population of bacteria in a dynamical Hostile Environment corresponding to the immune system of the colonized organism. The immune cells evolve as subcritical open clusters of oriented percolation and are perpetually reinforced by an immigration process, while the bacteria try to grow as a supercritical oriented percolation in the remaining empty space. We prove that the population of bacteria grows linearly when it survives. From this perspective, we build general tools to study dependent oriented percolation models issued from renormalization processes.

  • Growth of a population of bacteria in a dynamical Hostile Environment
    Advances in Applied Probability, 2014
    Co-Authors: Olivier Garet, Régine Marchand
    Abstract:

    We study the growth of a population of bacteria in a dynamical Hostile Environment corresponding to the immune system of the colonised organism. The immune cells evolve as subcritical open clusters of oriented percolation and are perpetually reinforced by an immigration process, while the bacteria try to grow as a supercritical oriented percolation in the remaining empty space. For appropriate values of the parameters, we prove that the population of bacteria grows linearly. In this perspective, we build general tools to study dependent percolation models issued from renormalization processes.