The rigidity of periodic body-bar frameworks on the three-dimensional fixed torus

We present necessary and sufficient conditions for the generic rigidity of body-bar frameworks on the three-dimensional fixed torus. These frameworks correspond to infinite periodic body-bar frameworks in $\mathbb{R}^3$ with a fixed periodic lattice.Comment: 31 pages, 12 figure

Food and Bodily Fabrication: An alimentary approach to personhood in Papua New Guinea

This paper exposes the integral role of food within the production of social configurations and the persons who constitute them in Papua New Guinea (PNG). The critical appraisal of current perspectives on food in PNG reveals the necessity of providing a theoretical framework that allows its exchange and consumption to be analysed simultaneously. In order to achieve this, a reconceptualisation of the body as fabricated is undertaken, which in turn, evokes  recent attempts to translate ‘ontological perspectivism’ into Melanesia. Drawing upon this theoretical manoeuvre, an ontologically significant relationship is elucidated between the ingestion of food, bodily transformation, and the production of different ‘types’ or ‘kinds’ of person in PNG. The reanalysis of data from existing ethnography reveals how persons throughout this region manipulate both external and internal relations through the exchange and consumption of food in order to activate crucial differentiations between persons. These arguments suggest that food should be elevated as a critical focus in anthropological studies of social processes in PNG, specifically those concerned with the activation of personhood. Keywords: food, ontological perspectivism, bodily transformation, social processes,personhoo

A note on heat and mass transfer from a sphere in Stokes\ud flow at low Péclet number

We consider the low Péclet number, Pe ≪ 1, asymptotic solution for steady-state heat and mass transfer from a sphere immersed in Stokes flow with a Robin boundary condition on its surface, representing Newton cooling or a first-order chemical reaction. The application of van Dyke’s rule up to terms of O(Pe3) shows that the O(Pe3 log Pe) terms in the expression for the average Nusselt/Sherwood number are double those previously derived in the literature. Inclusion of the O(Pe3) terms is shown to increase significantly the range of validity of the expansion

Nonuniqueness in a minimal model for cell motility

Two–phase flow models have been used previously to model cell motility, however these have rapidly become very complicated, including many physical processes, and are opaque. Here we demonstrate that even the simplest one–dimensional, two–phase, poroviscous, reactive flow model displays a number of behaviours relevant to cell crawling. We present stability analyses that show that an asymmetric perturbation is required to cause a spatially uniform, stationary strip of cytoplasm to move, which is relevant to cell polarization. Our numerical simulations identify qualitatively distinct families of travelling–wave solution that co–exist at certain parameter values. Within each family, the crawling speed of the strip has a bell–shaped dependence on the adhesion strength. The model captures the experimentally observed behaviour that cells crawl quickest at intermediate adhesion strengths, when the substrate is neither too sticky nor too slippy

The orbit rigidity matrix of a symmetric framework

A number of recent papers have studied when symmetry causes frameworks on a graph to become infinitesimally flexible, or stressed, and when it has no impact. A number of other recent papers have studied special classes of frameworks on generically rigid graphs which are finite mechanisms. Here we introduce a new tool, the orbit matrix, which connects these two areas and provides a matrix representation for fully symmetric infinitesimal flexes, and fully symmetric stresses of symmetric frameworks. The orbit matrix is a true analog of the standard rigidity matrix for general frameworks, and its analysis gives important insights into questions about the flexibility and rigidity of classes of symmetric frameworks, in all dimensions. With this narrower focus on fully symmetric infinitesimal motions, comes the power to predict symmetry-preserving finite mechanisms - giving a simplified analysis which covers a wide range of the known mechanisms, and generalizes the classes of known mechanisms. This initial exploration of the properties of the orbit matrix also opens up a number of new questions and possible extensions of the previous results, including transfer of symmetry based results from Euclidean space to spherical, hyperbolic, and some other metrics with shared symmetry groups and underlying projective geometry.Comment: 41 pages, 12 figure

Activation of the Listeria monocytogenes Virulence Program by a Reducing Environment.

Upon entry into the host cell cytosol, the facultative intracellular pathogen Listeria monocytogenes coordinates the expression of numerous essential virulence factors by allosteric binding of glutathione (GSH) to the Crp-Fnr family transcriptional regulator PrfA. Here, we report that robust virulence gene expression can be recapitulated by growing bacteria in a synthetic medium containing GSH or other chemical reducing agents. Bacteria grown under these conditions were 45-fold more virulent in an acute murine infection model and conferred greater immunity to a subsequent lethal challenge than bacteria grown in conventional media. During cultivation in vitro, PrfA activation was completely dependent on the intracellular levels of GSH, as a glutathione synthase mutant (ΔgshF) was activated by exogenous GSH but not reducing agents. PrfA activation was repressed in a synthetic medium supplemented with oligopeptides, but the repression was relieved by stimulation of the stringent response. These data suggest that cytosolic L. monocytogenes interprets a combination of metabolic and redox cues as a signal to initiate robust virulence gene expression in vivoIMPORTANCE Intracellular pathogens are responsible for much of the worldwide morbidity and mortality from infectious diseases. These pathogens have evolved various strategies to proliferate within individual cells of the host and avoid the host immune response. Through cellular invasion or the use of specialized secretion machinery, all intracellular pathogens must access the host cell cytosol to establish their replicative niches. Determining how these pathogens sense and respond to the intracellular compartment to establish a successful infection is critical to our basic understanding of the pathogenesis of each organism and for the rational design of therapeutic interventions. Listeria monocytogenes is a model intracellular pathogen with robust in vitro and in vivo infection models. Studies of the host-sensing and downstream signaling mechanisms evolved by L. monocytogenes often describe themes of pathogenesis that are broadly applicable to less tractable pathogens. Here, we describe how bacteria use external redox states as a cue to activate virulence

Functional vs. Traditional Resistance Training: Affective Response and Exercise Enjoyment in College-Age Females

As young women enter college-age, their rates of physical activity decrease while rates of psychological distress increase. Resistance training (RT) has been shown to have positive effects on the musculoskeletal system, glucose metabolism, body fat, insulin resistance, blood pressure, resting metabolic rate and psychological health. Within the types of RT, there is increased interest in functional resistance training (FRT), which uses multi-joint full-body movements; however few studies have been conducted to date examining FRT in college-aged females. Preliminary evidence indicates FRT leads to increases in fitness and may address the barriers common to traditional RT including embarrassment, enjoyment and concerns of masculinity. The purpose of this study is to compare affective responses, enjoyment, and self-efficacy between FRT and traditional resistance training (TRT) in college-age females. A randomized crossover experimental design in which each participant will experience both types of training in a random order is being conducted. Thirty-four females will be recruited to complete 2 sessions for each type of training, including a familiarization session where they will perform a 10-repetition maximum (RM) test for 8 exercises, followed by an assessment session with 2 sets of 10 repetitions for each exercise. Statistical analysis will include correlational test and paired t-tests to assess relationships between type of training and outcome variables of interest. It is hypothesized that females will experience greater enjoyment, positive affect and self-efficacy as well as decreased state anxiety in the FRT group as compared to the TRT group. Data collection is currently underway and preliminary results will be reported