Chiral Extrapolation of the Strangeness Changing K pi Form Factor

We perform a chiral extrapolation of lattice data on the scalar K pi form factor and the ratio of the kaon and pion decay constants within Chiral Perturbation Theory to two loops. We determine the value of the scalar form factor at zero momentum transfer, at the Callan-Treiman point and at its soft kaon analog as well as its slope. Results are in good agreement with their determination from experiment using the standard couplings of quarks to the W boson. The slope is however rather large. A study of the convergence of the chiral expansion is also performed.Comment: few minor change

Scale invariance and universality of force networks in static granular matter

Force networks form the skeleton of static granular matter. They are the key ingredient to mechanical properties, such as stability, elasticity and sound transmission, which are of utmost importance for civil engineering and industrial processing. Previous studies have focused on the global structure of external forces (the boundary condition), and on the probability distribution of individual contact forces. The disordered spatial structure of the force network, however, has remained elusive so far. Here we report evidence for scale invariance of clusters of particles that interact via relatively strong forces. We analyzed granular packings generated by molecular dynamics simulations mimicking real granular matter; despite the visual variation, force networks for various values of the confining pressure and other parameters have identical scaling exponents and scaling function, and thus determine a universality class. Remarkably, the flat ensemble of force configurations--a simple generalization of equilibrium statistical mechanics--belongs to the same universality class, while some widely studied simplified models do not.Comment: 15 pages, 4 figures; to appear in Natur

A study on job postures and musculoskeletal illnesses in dentists

Objectives: Musculoskeletal disorders (MSDs) compose a large part of occupational diseases in dental professionals, prevention of which is dependent on assessment and improvement of job postures by means of ergonomic interventions. This study was aimed at evaluation of ergonomic conditions of the profession of dentists and also at assessing the relationship between MSDs and conditions of work. Materials and Methods: This cross-sectional study was performed among 65 dentists using the method of Rapid Entire Body Assessment (REBA). The prevalence of MSDs was obtained by the use of the Nordic Musculoskeletal Questionnaire (NMQ). Results: In this investigation, the prevalence of MSDs for different body parts was: 75.9% for the neck, 58.6% for the shoulders, 56.9% for the upper back, 48.3% for the lower back and 44.8% for the wrist. Job analysis by the use of REBA showed that 89.6% of limbs in group A and 79.3% of limbs in group B had a score > 4. Only neck and lower back pain have significant relationship with the risk levels obtained using the REBA method. Conclusions: It can be concluded that work postures of dentists need to be improved. In addition to education, work station design, rest period during work and regular physical activities should be taken into account

Three-dimensional localization of ultracold atoms in an optical disordered potential

We report a study of three-dimensional (3D) localization of ultracold atoms suspended against gravity, and released in a 3D optical disordered potential with short correlation lengths in all directions. We observe density profiles composed of a steady localized part and a diffusive part. Our observations are compatible with the self-consistent theory of Anderson localization, taking into account the specific features of the experiment, and in particular the broad energy distribution of the atoms placed in the disordered potential. The localization we observe cannot be interpreted as trapping of particles with energy below the classical percolation threshold.Comment: published in Nature Physics; The present version is the initial manuscript (unchanged compared to version 1); The published version is available online at http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2256.htm

The semi-classical expansion and resurgence in gauge theories: new perturbative, instanton, bion, and renormalon effects

We study the dynamics of four dimensional gauge theories with adjoint fermions for all gauge groups, both in perturbation theory and non-perturbatively, by using circle compactification with periodic boundary conditions for the fermions. There are new gauge phenomena. We show that, to all orders in perturbation theory, many gauge groups are Higgsed by the gauge holonomy around the circle to a product of both abelian and nonabelian gauge group factors. Non-perturbatively there are monopole-instantons with fermion zero modes and two types of monopole-anti-monopole molecules, called bions. One type are "magnetic bions" which carry net magnetic charge and induce a mass gap for gauge fluctuations. Another type are "neutral bions" which are magnetically neutral, and their understanding requires a generalization of multi-instanton techniques in quantum mechanics - which we refer to as the Bogomolny-Zinn-Justin (BZJ) prescription - to compactified field theory. The BZJ prescription applied to bion-anti-bion topological molecules predicts a singularity on the positive real axis of the Borel plane (i.e., a divergence from summing large orders in peturbation theory) which is of order N times closer to the origin than the leading 4-d BPST instanton-anti-instanton singularity, where N is the rank of the gauge group. The position of the bion--anti-bion singularity is thus qualitatively similar to that of the 4-d IR renormalon singularity, and we conjecture that they are continuously related as the compactification radius is changed. By making use of transseries and Ecalle's resurgence theory we argue that a non-perturbative continuum definition of a class of field theories which admit semi-classical expansions may be possible.Comment: 112 pages, 7 figures; v2: typos corrected, discussion of supersymmetric models added at the end of section 8.1, reference adde

The effect of sepsis and its inflammatory response on mechanical clot characteristics: a prospective observational study

Purpose: Sepsis and its progression are known to have a major influence on the coagulation system. Current coagulation tests are of limited use when assessing coagulation in sepsis patients. This study aims to assess the potential for a new functional biomarker of clot microstructure, fractal dimension, to identify changes in the mechanical properties of clot microstructure across the sepsis spectrum (sepsis, severe sepsis and septic shock). Methods: A total of 100 patients that presented acutely to a large teaching hospital were included in this prospective observational study (50 sepsis, 20 severe sepsis and 30 septic shock) against a matched control of 44 healthy volunteers. Fractal analysis was performed, as well as standard markers of coagulation, and six plasma markers of inflammation. Results: Fractal dimension was significantly higher in the sepsis and severe sepsis groups than the healthy control (1.78 ± 0.07 and 1.80 ± 0.05 respectively vs 1.74 ± 0.03) (p < 0.001), indicating a significant increase in mechanical clot strength and elasticity consistent with a hypercoagulable state. Conversely, fractal dimension was significantly lower in septic shock (1.66 ± 0.10, p < 0.001), indicating a significant reduction in mechanical clot strength and functionality consistent with a hypocoagulable state. This corresponded with a significant increase in the inflammatory response. Conclusions: This study confirms that clot microstructure is significantly altered through the various stages of sepsis. Of particular importance was the marked change in clot development between severe sepsis and septic shock, which has not been previously reported

Arctic passages: liminality, I&#xF1;upiat Eskimo mothers and NW Alaska communities in transition

Background. While the primary goal of the NW Alaska Native maternal transport is safe deliveries for mothers from remote villages, little has been done to question the impact of transport on the mothers and communities involved. This study explores how presence of I&#xF1;upiat values influences the desire of indigenous women of differing eras and NW Alaska villages to participate in biomedical birth, largely made available by a tribal health-sponsored transport system. Objective. This paper portrays how important it is (and why) for Alaska Native families and women of different generations from various areas of I&#xF1;upiat villages of NW Alaska to get to the hospital to give birth. This research asks: How does a community&#x2019;s presence of I&#xF1;upiat values influence women of different eras and locations to participate in a more biomedical mode of birth? Design. Theoretical frameworks of medical anthropology and maternal identity work are used to track the differences in regard to the maternal transport operation for I&#xF1;upiat mothers of the area. Presence of I&#xF1;upiat values in each of the communities is compared by birth era and location for each village. Content analysis is conducted to determine common themes in an inductive, recursive fashion. Results. A connection is shown between a community&#x2019;s manifestation of I&#xF1;upiat cultural expression and mothers&#x2019; acceptance of maternal transport in this study. For this group of I&#xF1;upiat Eskimo mothers, there is interplay between community expression of I&#xF1;upiat values and desire and lengths gone to by women of different eras and locations. Conclusions. The more openly manifested the I&#xF1;upiat values of the community, the more likely alternative birthing practices sought, lessening the reliance on the existing transport policy. Conversely, the more openly western values are manifested in the village of origin, the less likely alternative measures are sought. For this study group, mothers from study villages with openly manifested western values are more likely to easily acquiesce to policy, and &#x201C;make the best&#x201D; of their prenatal travel

K pi vector form factor constrained by tau ---> K pi nu_tau and K_l3 decays

Dispersive representations of the Kpi vector and scalar form factors are used to fit the spectrum of tau ---> K pi nu_tau obtained by the Belle collaboration incorporating constraints from results for K_l3 decays. The slope and curvature of the vector form factor are obtained directly from the data through the use of a three-times-subtracted dispersion relation. We find $\lambda_+'=(25.49 \pm 0.31) \times 10^{-3}$ and $\lambda_+"= (12.22 \pm 0.14) \times 10^{-4}$. From the pole position on the second Riemann sheet the mass and width of the $K^*(892)^{\pm}$ are found to be $m_{K^*(892)^\pm}=892.0\pm 0.5$~MeV and $\Gamma_{K^*(892)^\pm}=46.5\pm 1.1$~MeV. The phase-space integrals needed for K_l3 decays are calculated as well. Furthermore, the Kpi isospin-1/2 P-wave threshold parameters are derived from the phase of the vector form factor. For the scattering length and the effective range we find respectively $a_{1}^{1/2}\,= ( 0.166\pm 0.004)\,m_\pi^{-3}$ and $b_{1}^{1/2}\,=( 0.258\pm 0.009)\,m_\pi^{-5}$.Comment: 22 pages, 4 figure