1,286 research outputs found
Characterization of spatiotemporal chaos in an inhomogeneous active medium
We study a reaction diffusion system of the activator-inhibitor type with
inhomogeneous reaction terms showing spatiotemporal chaos. We analyze the
topological properties of the unstable periodic orbits in the slow chaotic
dynamics appearing, which can be embedded in three dimensions. We perform a
bi-orthogonal decomposition analyzing the minimum number of modes necessary to
find the same organization of unstable orbits.Comment: 13 pages, 6 figs. Physica D (in press
Neurotransmitter-gated ion channels at fast chemical synapses: from structure to pathology
Fil: Bouzat, Cecilia Beatriz. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca; Argentin
Game theory in models of pedestrian room evacuation
We analyze the pedestrian evacuation of a rectangular room with a single door
considering a Lattice Gas scheme with the addition of behavioral aspects of the
pedestrians. The movement of the individuals is based on random and rational
choices and is affected by conflicts between two or more agents that want to
advance to the same position. Such conflicts are solved according to certain
rules closely related to the concept of strategies in Game Theory, cooperation
and defection. We consider game rules analogous to those from the Prisoner's
Dilemma and Stag Hunt games, with payoffs associated to the probabilities of
the individuals to advance to the selected site. We find that, even when
defecting is the rational choice for any agent, under certain conditions,
cooperators can take advantage from mutual cooperation and leave the room more
rapidly than defectors
Current and efficiency enhancement in Brownian motors driven by non Gaussian noises
We study Brownian motors driven by colored non Gaussian noises, both in the
overdamped regime and in the case with inertia, and analyze how the departure
of the noise distribution from Gaussian behavior can affect its behavior. We
analyze the problem from two alternative points of view: one oriented mainly to
possible technological applications and the other more inspired in natural
systems. In both cases we find an enhancement of current and efficiency due to
the non-Gaussian character of the noise. We also discuss the possibility of
observing an enhancement of the mass separation capability of the system when
non-Gaussian noises are considered.Comment: 11 pages, 9 figures, submitted to Europ. Phys. J.
Statistical fluctuations in pedestrian evacuation times and the effect of social contagion
Mathematical models of pedestrian evacuation and the associated simulation
software have become essential tools for the assessment of the safety of public
facilities and buildings. While a variety of models are now available, their
calibration and test against empirical data are generally restricted to global,
averaged quantities, the statistics compiled from the time series of individual
escapes (" microscopic " statistics) measured in recent experiments are thus
overlooked. In the same spirit, much research has primarily focused on the
average global evacuation time, whereas the whole distribution of evacuation
times over some set of realizations should matter. In the present paper we
propose and discuss the validity of a simple relation between this distribution
and the " microscopic " statistics, which is theoretically valid in the absence
of correlations. To this purpose, we develop a minimal cellular automaton, with
novel features that afford a semi-quantitative reproduction of the experimental
" microscopic " statistics. We then introduce a process of social contagion of
impatient behavior in the model and show that the simple relation under test
may dramatically fail at high contagion strengths, the latter being responsible
for the emergence of strong correlations in the system. We conclude with
comments on the potential practical relevance for safety science of
calculations based on " microscopic " statistics
Caenorhabditis elegans muscle Cys-loop receptors as novel targets of terpenoids with potential anthelmintic activity
The anthelmintic treatment of nematode infections remains the pillar of worm control in both human and veterinary medicine. Since control is threatened by the appearance of drug resistant nematodes, there is a need to develop novel compounds, among which phytochemicals constitute potential anthelmintic agents. Caenorhabditis elegans has been pivotal in anthelmintic drug discovery and in revealing mechanisms of drug action and resistance. By using C. elegans, we here revealed the anthelmintic actions of three plant terpenoids -thymol, carvacrol and eugenol- at the behavioral level. Terpenoids produce a rapid paralysis of worms with a potency rank order carvacrol > thymol > eugenol. In addition to their paralyzing activity, they also inhibit egg hatching, which would, in turn, lead to a broader anthelmintic spectrum of activity. To identify drug targets, we performed an in vivo screening of selected strains carrying mutations in receptors involved in worm locomotion for determining resistance to the paralyzing effect of terpenoids. The assays revealed that two Cys-loop receptors with key roles in worm locomotion -Levamisole sensitive nicotinic receptor (L-AChR) and GABA(A) (UNC-49) receptor- are involved in the paralyzing effects of terpenoids. To decipher the mechanism by which terpenoids affect these receptors, we performed electrophysiological studies using a primary culture of C. elegans L1 muscle cells. Whole cell recordings from L1 cells demonstrated that terpenoids decrease macroscopic responses of L-AChR and UNC-49 receptor to their endogenous agonists, thus acting as inhibitors. Single-channel recordings from L-AChR revealed that terpenoids decrease the frequency of opening events, probably by acting as negative allosteric modulators. The fact that terpenoids act at different receptors may have important advantages regarding efficacy and development of resistance. Thus, our findings give support to the use of terpenoids as either an alternative or a complementary anthelmintic strategy to overcome the ever-increasing resistance of parasites to classical anthelmintic drugs.Fil: Hernando, Guillermina Silvana. Universidad Nacional del Sur. Departamento de BiologĂa, BioquĂmica y Farmacia; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca; ArgentinaFil: Turani, Ornella. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca; Argentina. Universidad Nacional del Sur. Departamento de BiologĂa, BioquĂmica y Farmacia; ArgentinaFil: Bouzat, Cecilia Beatriz. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - BahĂa Blanca. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca. Universidad Nacional del Sur. Instituto de Investigaciones BioquĂmicas de BahĂa Blanca; Argentina. Universidad Nacional del Sur. Departamento de BiologĂa, BioquĂmica y Farmacia; Argentin
- …