Reversing a granular flow on a vibratory conveyor

Experimental results are presented on the transport properties of granular materials on a vibratory conveyor. For circular oscillations of the shaking trough a non-monotonous dependence of the transport velocity on the normalized acceleration is observed. Two maxima are separated by a regime, where the granular flow is much slower and, in a certain driving range, even reverses its direction. A similar behavior is found for a single solid body with a low coefficient of restitution, whereas an individual glass bead of 1 mm diameter is propagated in the same direction for all accelerations.Comment: 4 pages, 5 figures, submitted to Applied Physics Letter

Spontaneous Ratchet Effect in a Granular Gas

The spontaneous clustering of a vibrofluidized granular gas is employed to generate directed transport in two different compartmentalized systems: a "granular fountain" in which the transport takes the form of convection rolls, and a "granular ratchet" with a spontaneous particle current perpendicular to the direction of energy input. In both instances, transport is not due to any system-intrinsic anisotropy, but arises as a spontaneous collective symmetry breaking effect of many interacting granular particles. The experimental and numerical results are quantitatively accounted for within a flux model.Comment: 4 pages, 5 figures; Fig. 4 has been reduced in size and qualit

Multivalent display of minimal Clostridium difficile glycan epitopes mimics antigenic properties of larger glycans

Synthetic cell-surface glycans are promising vaccine candidates against Clostridium difficile. The complexity of large, highly antigenic and immunogenic glycans is a synthetic challenge. Less complex antigens providing similar immune responses are desirable for vaccine development. Based on molecular-level glycan-antibody interaction analyses, we here demonstrate that the C. difficile surface polysaccharide-I (PS-I) can be resembled by multivalent display of minimal disaccharide epitopes on a synthetic scaffold that does not participate in binding. We show that antibody avidity as a measure of antigenicity increases by about five orders of magnitude when disaccharides are compared with constructs containing five disaccharides. The synthetic, pentavalent vaccine candidate containing a peptide T-cell epitope elicits weak but highly specific antibody responses to larger PS-I glycans in mice. This study highlights the potential of multivalently displaying small oligosaccharides to achieve antigenicity characteristic of larger glycans. The approach may result in more cost-efficient carbohydrate vaccines with reduced synthetic effort

Skin microbiota analysis in patients with anorexia nervosa and healthy-weight controls reveals microbial indicators of healthy weight and associations with the antimicrobial peptide psoriasin

Anorexia nervosa (AN), a psychiatric condition defined by low body weight for age and height, is associated with numerous dermatological conditions. Yet, clinical observations report that patients with AN do not suffer from infectious skin diseases like those associated with primary malnutrition. Cell-mediated immunity appears to be amplified in AN; however, this proinflammatory state does not sufficiently explain the lower incidence of infections. Antimicrobial peptides (AMPs) are important components of the innate immune system protecting from pathogens and shaping the microbiota. In Drosophila melanogaster starvation precedes increased AMP gene expression. Here, we analyzed skin microbiota in patients with AN and age-matched, healthy-weight controls and investigated the influence of weight gain on microbial community structure. We then correlated features of the skin microbial community with psoriasin and RNase 7, two highly abundant AMPs in human skin, to clarify whether an association between AMPs and skin microbiota exists and whether such a relationship might contribute to the resistance to cutaneous infections observed in AN. We find significant statistical correlations between Shannon diversity and the highly abundant skin AMP psoriasin and bacterial load, respectively. Moreover, we reveal psoriasin significantly associates with Abiotrophia, an indicator for the healthy-weight control group. Additionally, we observe a significant correlation between an individual’s body mass index and Lactobacillus, a microbial indicator of health. Future investigation may help clarify physiological mechanisms that link nutritional intake with skin physiology

Riemann solvers and undercompressive shocks of convex FPU chains

We consider FPU-type atomic chains with general convex potentials. The naive continuum limit in the hyperbolic space-time scaling is the p-system of mass and momentum conservation. We systematically compare Riemann solutions to the p-system with numerical solutions to discrete Riemann problems in FPU chains, and argue that the latter can be described by modified p-system Riemann solvers. We allow the flux to have a turning point, and observe a third type of elementary wave (conservative shocks) in the atomistic simulations. These waves are heteroclinic travelling waves and correspond to non-classical, undercompressive shocks of the p-system. We analyse such shocks for fluxes with one or more turning points. Depending on the convexity properties of the flux we propose FPU-Riemann solvers. Our numerical simulations confirm that Lax-shocks are replaced by so called dispersive shocks. For convex-concave flux we provide numerical evidence that convex FPU chains follow the p-system in generating conservative shocks that are supersonic. For concave-convex flux, however, the conservative shocks of the p-system are subsonic and do not appear in FPU-Riemann solutions

Methods for reproductive tract scoring as a tool for improving sow productivity

Improving sow lifetime productivity (SLP) is essential for maximizing farm profitability. Study objectives were to determine the accuracy for different vulva scoring methods in a commercial production system and to assess whether gilt reproductive tract scoring (evaluated by vulva width; VW) prior to puberty could serve as useful gilt selection criteria. To accomplish this objective, 958 prepubertal replacement gilts in a commercial system were evaluated at approximately 15 weeks of age. Gilt body weight was recorded in addition to four different methods to evaluate VW. Methods for VW assessment included digital caliper measurement (mm), visual evaluation and scoring by trained farm personnel (Farm Score; FS), and two methods using scoring tools (Vulva Score Method A and B; VSA and VSB, respectively) specifically calibrated from the VW distribution measured on gilts from previous studies. The VSA and FS methods assigned gilts to one of three categories (S, M, L and 1, 2, 3, respectively) whereas VSB classified gilts vulvas using a five-point scoring system (1 to 5). At 15-wk of age, a low proportion of variability in vulva size (27.8 ± 0.1 mm) could be explained by BW (62.2 ± 0.2 kg; R2 = 0.05). All three scoring methods were effective in categorizing gilts based upon VW, as the measured VW size within methods differed by score (P \u3c 0.01). The proportion of gilts achieving their first parity increased with score for VSA (64.7, 73.2, and 84.4%; P = 0.02), VSB (66.0, 71.7, 79.2, 76.4, and 84.2%; P = 0.02), and FS (67.2, 75.0, and 88.8%; P = 0.03), but VSA, VSB, and FS did not influence percentage of gilts achieving their second parity (P = 0.32, 0.29, and 0.30, respectively). Litter performance of gilts scored as M or L using VSA improved with an increased total born over two parities compared to those scored as S (23.96 vs. 26.38 pigs; P \u3c 0.01) as well as born alive (21.13 vs. 23.05 pigs; P \u3c 0.05). Results were similar for VSB, where scores 2-5 had greater total born (23.97 vs. 26.33 pigs; P \u3c 0.01) and born alive (21.11 vs. 23.02 pigs; P \u3c 0.05) through two parities compared to gilts scored 1. Using the FS method, total born pigs tended to be increased (P = 0.06) through two parities for gilts having a 2 or 3 vulva score compared to those scored as a 1. Collectively, assessing VW at approximately 15 wk of age may identify sows with improved productivity through two parities as breeding herd females

Automated laser-transfer synthesis of high-density microarrays for infectious disease screening

Abstract Laser-induced forward transfer (LIFT) is a rapid laser-patterning technique for high-throughput combinatorial synthesis directly on glass slides. A lack of automation and precision limited LIFT applications to simple proof-of-concept syntheses of fewer than 100 compounds. Here, we report an automated synthesis instrument that combines laser transfer and robotics for parallel synthesis in a microarray format with up to 10000 individual reactions/cm2. An optimized pipeline for amide bond formation is the basis for preparing complex peptide microarrays with thousands of different sequences in high yield with high reproducibility. The resulting peptide arrays are of higher quality than commercial peptide arrays. More than 4800 15-residue peptides resembling the entire Ebola virus proteome on a microarray were synthesized to study the antibody response of an Ebola virus infection survivor. We identified known and unknown epitopes that serve now as a basis for Ebola diagnostic development. The versatility and precision of the synthesizer is demonstrated by in situ synthesis of fluorescent molecules via Schiff base reaction and multi-step patterning of precisely definable amounts of fluorophores. This automated laser transfer synthesis approach opens new avenues for high-throughput chemical synthesis and biological screening

On-chip neo-glycopeptide synthesis for multivalent glycan presentation

Single glycan-protein interactions are often weak, such that glycan binding partners commonly utilize multiple, spatially defined binding sites to enhance binding avidity and specificity. Current array technologies usually neglect defined multivalent display. Laser-based array synthesis technology allows for flexible and rapid on-surface synthesis of different peptides. Combining this technique with click chemistry, we produced neo-glycopeptides directly on a functionalized glass slide in the microarray format. Density and spatial distribution of carbohydrates can be tuned, resulting in well-defined glycan structures for multivalent display. We probed the two lectins concanavalin A and langerin with different glycans on multivalent scaffolds, revealing strong spacing-, density-, and ligand-dependent binding. In addition, we could also measure the surface dissociation constant. This approach allows for a rapid generation, screening, and optimization of a multitude of multivalent scaffolds for glycan binding

Hall Normalization Constants for the Bures Volumes of the n-State Quantum Systems

We report the results of certain integrations of quantum-theoretic interest, relying, in this regard, upon recently developed parameterizations of Boya et al of the n x n density matrices, in terms of squared components of the unit (n-1)-sphere and the n x n unitary matrices. Firstly, we express the normalized volume elements of the Bures (minimal monotone) metric for n = 2 and 3, obtaining thereby "Bures prior probability distributions" over the two- and three-state systems. Then, as an essential first step in extending these results to n > 3, we determine that the "Hall normalization constant" (C_{n}) for the marginal Bures prior probability distribution over the (n-1)-dimensional simplex of the n eigenvalues of the n x n density matrices is, for n = 4, equal to 71680/pi^2. Since we also find that C_{3} = 35/pi, it follows that C_{4} is simply equal to 2^{11} C_{3}/pi. (C_{2} itself is known to equal 2/pi.) The constant C_{5} is also found. It too is associated with a remarkably simple decompositon, involving the product of the eight consecutive prime numbers from 2 to 23. We also preliminarily investigate several cases, n > 5, with the use of quasi-Monte Carlo integration. We hope that the various analyses reported will prove useful in deriving a general formula (which evidence suggests will involve the Bernoulli numbers) for the Hall normalization constant for arbitrary n. This would have diverse applications, including quantum inference and universal quantum coding.Comment: 14 pages, LaTeX, 6 postscript figures. Revised version to appear in J. Phys. A. We make a few slight changes from the previous version, but also add a subsection (III G) in which several variations of the basic problem are newly studied. Rather strong evidence is adduced that the Hall constants are related to partial sums of denominators of the even-indexed Bernoulli numbers, although a general formula is still lackin

On the energy functional on Finsler manifolds and applications to stationary spacetimes

In this paper we first study some global properties of the energy functional on a non-reversible Finsler manifold. In particular we present a fully detailed proof of the Palais--Smale condition under the completeness of the Finsler metric. Moreover we define a Finsler metric of Randers type, which we call Fermat metric, associated to a conformally standard stationary spacetime. We shall study the influence of the Fermat metric on the causal properties of the spacetime, mainly the global hyperbolicity. Moreover we study the relations between the energy functional of the Fermat metric and the Fermat principle for the light rays in the spacetime. This allows us to obtain existence and multiplicity results for light rays, using the Finsler theory. Finally the case of timelike geodesics with fixed energy is considered.Comment: 23 pages, AMSLaTeX. v4 matches the published versio