Two-Player Reachability-Price Games on Single-Clock Timed Automata

We study two player reachability-price games on single-clock timed automata. The problem is as follows: given a state of the automaton, determine whether the first player can guarantee reaching one of the designated goal locations. If a goal location can be reached then we also want to compute the optimum price of doing so. Our contribution is twofold. First, we develop a theory of cost functions, which provide a comprehensive methodology for the analysis of this problem. This theory allows us to establish our second contribution, an EXPTIME algorithm for computing the optimum reachability price, which improves the existing 3EXPTIME upper bound.Comment: In Proceedings QAPL 2011, arXiv:1107.074

Optimal Reachability in Divergent Weighted Timed Games

Weighted timed games are played by two players on a timed automaton equipped with weights: one player wants to minimise the accumulated weight while reaching a target, while the other has an opposite objective. Used in a reactive synthesis perspective, this quantitative extension of timed games allows one to measure the quality of controllers. Weighted timed games are notoriously difficult and quickly undecidable, even when restricted to non-negative weights. Decidability results exist for subclasses of one-clock games, and for a subclass with non-negative weights defined by a semantical restriction on the weights of cycles. In this work, we introduce the class of divergent weighted timed games as a generalisation of this semantical restriction to arbitrary weights. We show how to compute their optimal value, yielding the first decidable class of weighted timed games with negative weights and an arbitrary number of clocks. In addition, we prove that divergence can be decided in polynomial space. Last, we prove that for untimed games, this restriction yields a class of games for which the value can be computed in polynomial time

Effect of Media and Estrogen on Morphological Change in Candida albicans

Introduction: Candida albicans (C. albicans), an opportunistic pathogen, lives symbiotically within the intestine of its human host. Temperature and chemical factors have been shown to induce a morphological change in C. albicans from yeast to filamentous form turning C. albicans pathogenic. In this study, we investigated the intestinal cues that might be responsible for the change. We found that different solid media impact the morphological phenotype so we focused on characterizing these before further testing. We tested Estradiol (E2) because of its known linkage to sepsis and higher levels during infections. Experiments were conducted to compare solid agar plates of YEPD, Minimal Media (MM), and Spider Media (SP) for C. albicans growth to choose the best one for further testing with E2 and other factors that could be prone to causing morphological changes. Methods: C. albicans was inoculated through streak method on different solid media (YEPD, MM, SP) and incubated at 30℃. The effect of 0.1nM E2 on C. albicans morphology was also tested. Morphological changes were assayed through bright-field microscopy. Results: Using the three different medias, we found three distinctive phenotypes: A, B, and C. Out of 6 experiments of 14 MM plates, the expressed phenotype was 86% A and 14% inconclusive of the time. 8 experiments of 17 SP plates showed 100% of phenotype B. 6 experiments of 14 YEPD plates presented phenotype C 92% of the time and 8% inconclusive. For E2 trials, 2 experiments, 6 MM plates showed 50% phenotype A and 50% inconclusive. 4 experiments, 10 SP plates had phenotype B 100%. YEPD 2 experiments, 2 plates had phenotype C at 100%. Conclusion: We have established experimental conditions of media controls for further testing whether E2 and other cues, such as inflammatory cytokines, have inhibitory or positive effects on the growth of C. albicans

One-dimensional description of a Bose-Einstein condensate in a rotating closed-loop waveguide

We propose a general procedure for reducing the three-dimensional Schrodinger equation for atoms moving along a strongly confining atomic waveguide to an effective one-dimensional equation. This procedure is applied to the case of a rotating closed-loop waveguide. The possibility of including mean-field atomic interactions is presented. Application of the general theory to characterize a new concept of atomic waveguide based on optical tweezers is finally discussed

Momentum spectroscopy of 1D phase fluctuations in Bose-Einstein condensates

We measure the axial momentum distribution of Bose-Einstein condensates with an aspect ratio of 152 using Bragg spectroscopy. We observe the Lorentzian momentum distribution characteristic of one-dimensional phase fluctuations. The temperature dependence of the width of this distribution provides a quantitative test of quasi-condensate theory. In addition, we observe a condensate length consistent with the absence of density fluctuations, even when phase fluctuations are large.Comment: 4 pages, 3 figures; submitted to Phys. Rev. Let

Verification and Control of Partially Observable Probabilistic Real-Time Systems

We propose automated techniques for the verification and control of probabilistic real-time systems that are only partially observable. To formally model such systems, we define an extension of probabilistic timed automata in which local states are partially visible to an observer or controller. We give a probabilistic temporal logic that can express a range of quantitative properties of these models, relating to the probability of an event's occurrence or the expected value of a reward measure. We then propose techniques to either verify that such a property holds or to synthesise a controller for the model which makes it true. Our approach is based on an integer discretisation of the model's dense-time behaviour and a grid-based abstraction of the uncountable belief space induced by partial observability. The latter is necessarily approximate since the underlying problem is undecidable, however we show how both lower and upper bounds on numerical results can be generated. We illustrate the effectiveness of the approach by implementing it in the PRISM model checker and applying it to several case studies, from the domains of computer security and task scheduling

Momentum Spectroscopy of Phase Fluctuations of an Elongated Bose-Einstein Condensate

We have measured the momentum distribution of an elongated BEC (aspect ratio of 152), for temperatures below the critical temperature. The corresponding coherence length is significantly smaller than the condensate length in a wide range of temperature, in quantitative agreement with theoretical predictions. The Lorentzian shape of the momentum spectrum supports the image of a phase fluctuating quasicondensate.Comment: Proceedings of the International Conference on Laser Spectroscopy (ICOLS 03), Cairns, Australia, july 200

One-dimensional behavior of elongated Bose-Einstein condensates

We study the properties of elongated Bose-Einstein condensates. First, we show that the dimensions of the condensate after expansion differs from the 3D Thomas-Fermi regime. We also study the coherence length of such elongated condensates.Comment: proceeding of Quantum Gases in Low Dimension, Les Houches 2003, 8 pages, 5 figure