Ponazuril Inhibits the Development of Eimeria Vermiformis in Experimentally Infected Outbred Swiss Mice

We evaluated a 15% paste formulation of ponazuril in outbred Swiss mice that were experimentally infected with Eimeria vermiformis. Thirty, 8-week-old female mice (approximately 20 g) were placed in one group of 10 mice and one group of 20 mice. Mice in both groups were gavaged with approximately 5,000 sporulated oocysts of E. vermiformis on day 0. Mice in group 2 (n=10) were treated orally on days 3 and 4 with ponazuril (suspended in 30% propylene glycol) at the rate of 20 mg/kg. Mice in group 1 (n=20) were gavaged with a similar volume of 30% propylene glycol. Rates of oocyst passage (oocysts/g feces) were determined on day 10 (peak patency) for treated and nontreated mice using a fecal aliquot oocyst counting technique. Oocysts were not observed in the feces of treated mice using the aliquot technique. Control mice passaged oocysts at a geometric mean rate of \u3e104,000 oocysts/g feces. Control mice also produced significantly less feces on day 10. These results indicate that ponazuril is effective against E. vermiformis under the conditions utilized in this study, and that the E. vermiformis mouse model could be useful in predicting the efficacy of new anticoccidial drugs. © Springer-Verlag 2004

The 2+1 flavor topological susceptibility from the asqtad action at 0.06 fm

We report new data for the topological susceptibility computed on 2+1 flavor dynamical configurations with lattice spacing 0.06 fm, generated with the asqtad action. The topological susceptibility is computed by HYP smearing and compared with rooted staggered chiral perturbation theory as the pion mass goes to zero. At 0.06 fm, the raw data is already quite close to the continuum extrapolated values obtained from coarser lattices. These results provide a further test of the asqtad action with rooted staggered flavors.Comment: 7 pages, 5 figures, talk presented at the XXV International Symposium on Lattice Field Theory, July 30 - August 4, 2007, Regensburg, German

Topological susceptibility with the asqtad action

Chiral perturbation theory predicts that in quantum chromodynamics (QCD), light dynamical quarks suppress the gauge-field topological susceptibility of the vacuum. The degree of suppression depends on quark multiplicity and masses. It provides a strong consistency test for fermion formulations in lattice QCD. Such tests are especially important for staggered fermion formulations that lack a full chiral symmetry and use the "fourth-root" procedure to achieve the desired number of sea quarks. Over the past few years we have measured the topological susceptibility on a large database of 18 gauge field ensembles, generated in the presence of 2+1 flavors of dynamical asqtad quarks with up and down quark masses ranging from 0.05 to 1 in units of the strange quark mass and lattice spacings ranging from 0.045 fm to 0.12 fm. Our study also includes three quenched ensembles with lattice spacings ranging from 0.06 to 0.12 fm. We construct the topological susceptibility from the integrated point-to-point correlator of the discretized topological charge density F-Fdual. To reduce its variance, we model the asymptotic tail of the correlator. The continuum extrapolation of our results for the topological susceptibility agrees nicely at small quark mass with the predictions of lowest-order SU(3) chiral perturbation theory, thus lending support to the validity of the fourth-root procedure.Comment: 28 pp, 6 figs. Version 2 corrects some discussion, some numbers, and some figures and adds some reference

Drag on particles in a nematic suspension by a moving nematic-isotropic interface

We report the first clear demonstration of drag on colloidal particles by a moving nematic-isotropic interface. The balance of forces explains our observation of periodic, strip-like structures that are produced by the movement of these particles

Theory of Banana Liquid Crystal Phases and Phase Transitions

We study phases and phase transitions that can take place in the newly discovered banana (bow-shaped or bent-core) liquid crystal molecules. We show that to completely characterize phases exhibited by such bent-core molecules a third-rank tensor $T^{ijk}$ order parameter is necessary in addition to the vector and the nematic (second-rank) tensor order parameters. We present an exhaustive list of possible liquid phases, characterizing them by their space-symmetry group and order parameters, and catalog the universality classes of the corresponding phase transitions that we expect to take place in such bent-core molecular liquid crystals. In addition to the conventional liquid-crystal phases such as the nematic phase, we predict the existence of novel liquid phases, including the spontaneously chiral nematic $(N_T + 2)^*$ and chiral polar $(V_T + 2)^*$ phases, the orientationally-ordered but optically isotropic tetrahedratic $T$ phase, and a novel nematic $N_T$ phase with $D_{2d}$ symmetry that is neither uniaxial nor biaxial. Interestingly, the Isotropic-Tetrahedratic transition is {\em continuous} in mean-field theory, but is likely driven first-order by thermal fluctuations. We conclude with a discussion of smectic analogs of these phases and their experimental signatures.Comment: 28 pgs. RevTex, 32 eps figures, submitted to Phys. Rev.

Transient transcriptional events in human skeletal muscle at the outset of concentric resistance exercise training

We sought to ascertain the time course of transcriptional events that occur in human skeletal muscle at the outset of resistance exercise (RE) training in RE naive individuals and determine whether the magnitude of response was associated with exercise-induced muscle damage. Sixteen RE naive men were recruited; eight underwent two sessions of 5 × 30 maximum isokinetic knee extensions (180°/s) separated by 48 h. Muscle biopsies of the vastus lateralis, obtained from different sites, were taken at baseline and 24 h after each exercise bout. Eight individuals acted as nonexercise controls with biopsies obtained at the same time intervals. Transcriptional changes were assessed by microarray and protein levels of heat shock protein (HSP) 27 and αB-crystallin in muscle cross sections by immunohistochemistry as a proxy measure of muscle damage. In control subjects, no probe sets were significantly altered (false discovery rate < 0.05), and HSP27 and αB-crystallin protein remained unchanged throughout the study. In exercised subjects, significant intersubject variability following the initial RE bout was observed in the muscle transcriptome, with greatest changes occurring in subjects with elevated HSP27 and αB-crystallin protein. Following the second bout, the transcriptome response was more consistent, revealing a cohort of probe sets associated with immune activation, the suppression of oxidative metabolism, and ubiquitination, as differentially regulated. The results reveal that the initial transcriptional response to RE is variable in RE naive volunteers, potentially associated with muscle damage and unlikely to reflect longer term adaptations to RE training. These results highlight the importance of considering multiple time points when determining the transcriptional response to RE and associated physiological adaptation

Mechanosensory interactions drive collective behaviour in Drosophila.

Collective behaviour enhances environmental sensing and decision-making in groups of animals. Experimental and theoretical investigations of schooling fish, flocking birds and human crowds have demonstrated that simple interactions between individuals can explain emergent group dynamics. These findings indicate the existence of neural circuits that support distributed behaviours, but the molecular and cellular identities of relevant sensory pathways are unknown. Here we show that Drosophila melanogaster exhibits collective responses to an aversive odour: individual flies weakly avoid the stimulus, but groups show enhanced escape reactions. Using high-resolution behavioural tracking, computational simulations, genetic perturbations, neural silencing and optogenetic activation we demonstrate that this collective odour avoidance arises from cascades of appendage touch interactions between pairs of flies. Inter-fly touch sensing and collective behaviour require the activity of distal leg mechanosensory sensilla neurons and the mechanosensory channel NOMPC. Remarkably, through these inter-fly encounters, wild-type flies can elicit avoidance behaviour in mutant animals that cannot sense the odour--a basic form of communication. Our data highlight the unexpected importance of social context in the sensory responses of a solitary species and open the door to a neural-circuit-level understanding of collective behaviour in animal groups

Simulating Particle Dispersions in Nematic Liquid-Crystal Solvents

A new method is presented for mesoscopic simulations of particle dispersions in nematic liquid crystal solvents. It allows efficient first-principle simulations of the dispersions involving many particles with many-body interactions mediated by the solvents. A simple demonstration is shown for the aggregation process of a two dimentional dispersion.Comment: 5 pages, 5 figure

A Smooth Interface Method for Simulating Liquid Crystal Colloid Dispersions

A new method is presented for mesoscopic simulations of particle dispersions in liquid crystal solvents. It allows efficient first-principle simulations of the dispersions involving many particles with many-body interactions mediated by the solvents. Demonstrations have been performed for the aggregation of colloid dispersions in two-dimensional nematic and smectic-C* solvents neglecting hydrodynamic effects, which will be taken into account in the near future.Comment: 13 pages, 4 figure

Phase-ordering dynamics of the Gay-Berne nematic liquid crystal

Phase-ordering dynamics in nematic liquid crystals has been the subject of much active investigation in recent years in theory, experiments and simulations. With a rapid quench from the isotropic to nematic phase a large number of topological defects are formed and dominate the subsequent equilibration process. We present here the results of a molecular dynamics simulation of the Gay-Berne model of liquid crystals after such a quench in a system with 65536 molecules. Twist disclination lines as well as type-1 lines and monopoles were observed. Evidence of dynamical scaling was found in the behavior of the spatial correlation function and the density of disclination lines. However, the behavior of the structure factor provides a more sensitive measure of scaling, and we observed a crossover from a defect dominated regime at small values of the wavevector to a thermal fluctuation dominated regime at large wavevector.Comment: 18 pages, 16 figures, animations available at http://www.physics.brown.edu/Users/faculty/pelcovits/lc/coarsening.htm