Perturbative renormalization of the electric field correlator

The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ~12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.Comment: 15 pages. v2: published versio

A remark on higher dimension induced domain wall defects in our world

There has been recent interest in new types of topological defects arising in models with compact extra dimensions. We discuss in this context the old statement that if only SU(N) gauge fields and adjoint matter live in the bulk, and the coupling is weak, then the theory possesses a spontaneously broken global Z(N) symmetry, with associated domain wall defects in four dimensions. We discuss the behaviour of this symmetry at high temperatures. We argue that the symmetry gets restored, so that cosmological domain wall production could be used to constrain such models.Comment: 12 pages. Presentation clarified, references added; to appear in Phys.Lett.

Four-loop lattice-regularized vacuum energy density of the three-dimensional SU(3) + adjoint Higgs theory

The pressure of QCD admits at high temperatures a factorization into purely perturbative contributions from "hard" thermal momenta, and slowly convergent as well as non-perturbative contributions from "soft" thermal momenta. The latter can be related to various effective gluon condensates in a dimensionally reduced effective field theory, and measured there through lattice simulations. Practical measurements of one of the relevant condensates have suffered, however, from difficulties in extrapolating convincingly to the continuum limit. In order to gain insight on this problem, we employ Numerical Stochastic Perturbation Theory to estimate the problematic condensate up to 4-loop order in lattice perturbation theory. Our results seem to confirm the presence of "large" discretization effects, going like $a\ln(1/a)$, where $a$ is the lattice spacing. For definite conclusions, however, it would be helpful to repeat the corresponding part of our study with standard lattice perturbation theory techniques.Comment: 35 pages. v2: minor corrections, published versio

Four-loop pressure of massless O(N) scalar field theory

Inspired by the corresponding problem in QCD, we determine the pressure of massless O(N) scalar field theory up to order g^6 in the weak-coupling expansion, where g^2 denotes the quartic coupling constant. This necessitates the computation of all 4-loop vacuum graphs at a finite temperature: by making use of methods developed by Arnold and Zhai at 3-loop level, we demonstrate that this task is manageable at least if one restricts to computing the logarithmic terms analytically, while handling the ``constant'' 4-loop contributions numerically. We also inspect the numerical convergence of the weak-coupling expansion after the inclusion of the new terms. Finally, we point out that while the present computation introduces strategies that should be helpful for the full 4-loop computation on the QCD-side, it also highlights the need to develop novel computational techniques, in order to be able to complete this formidable task in a systematic fashion.Comment: 34 page

The leading non-perturbative coefficient in the weak-coupling expansion of hot QCD pressure

Using Numerical Stochastic Perturbation Theory within three-dimensional pure SU(3) gauge theory, we estimate the last unknown renormalization constant that is needed for converting the vacuum energy density of this model from lattice regularization to the MSbar scheme. Making use of a previous non-perturbative lattice measurement of the plaquette expectation value in three dimensions, this allows us to approximate the first non-perturbative coefficient that appears in the weak-coupling expansion of hot QCD pressure.Comment: 16 pages. v2: published versio

Renormalization of infrared contributions to the QCD pressure

Thanks to dimensional reduction, the infrared contributions to the QCD pressure can be obtained from two different three-dimensional effective field theories, called the Electrostatic QCD (Yang-Mills plus adjoint Higgs) and the Magnetostatic QCD (pure Yang-Mills theory). Lattice measurements have been carried out within these theories, but a proper interpretation of the results requires renormalization, and in some cases also improvement, i.e. the removal of terms of O(a) or O(a^2). We discuss how these computations can be implemented and carried out up to 4-loop level with the help of Numerical Stochastic Perturbation Theory.Comment: 7 pages, 4 figures, talk presented at Lattice 2006 (High temperature and density

CHARACTERIZATION OF AND CONTROLLING MORPHOLOGY OF ULTRA-THIN NANOCOMPOSITES

Ultrathin film nanocomposites are becoming increasingly important for specialized performance of commercial coatings. Critical challenges for ultrathin film nanocomposites include their synthesis and characterization as well as their performance properties, including surface roughness, optical properties (haze, refractive index as examples), and mechanical properties. The objective of this work is to control the surface roughness of ultrathin film nanocomposites by changing the average particle size and the particle volume fraction (loading) of monomodal particle size distributions. This work evaluated one-layer and two-layer films for their surface properties. Monodispersed colloidal silica nanoparticles were incorporated into an acrylate-based monomer system as the model system. Ultrathin nanocomposites were prepared with three different size colloidal silica (13, 45, and 120 nm nominal diameters) at three different particle loadings (20, 40, and 50 vol. % inorganic solids). Silica particles were characterized using DLS and TEM. AFM was used to measure the root mean square roughness (Rq), ΔZ, and location-to-location uniformity of one-layer and two-layer nanocomposite coatings. Developing an understanding about the properties affected by the type and amount of particles used in a nanocomposite can be used as a tool with nanocharacterization techniques to quickly modify and synthesize desired ultrathin film coatings

THE PREVALENCE OF PRACTICING SAFETY PROFESSIONALS’ KNOWLEDGE, INVOLVEMENT, AND COMPETENCY ASSOCIATED WITH WORKPLACE WELLNESS PROGRAMS: GAUGING THE SAFETY PROFESSION’S ENGAGEMENT WITH THE TOTAL WORKER HEALTH INITIATIVE

The morbidity and mortality burden of occupational injuries and illnesses in the United States became such a public health concern that in 1970 the Occupational Safety and Health Act was signed into law. This law requires employers to provide workplaces “free from recognized hazards” and spurred the development of specific regulations along with the creation of academic and professional training programs to educate individuals about the safety sciences and careers in safety fields. Today there are an estimated 26,000 professionally trained and board certified safety professionals supporting workplace programs across the country, alongside numerous non-certified, but degreed, practicing safety professionals. While the collective efforts of these professionals has served to significantly reduce the rate of workplace injuries and illnesses, an emerging body of scientific knowledge indicates that the health status of any worker is affected by both occupational and non-occupational exposures. The failure to consider both impacts an employee’s “total worker health”. Led by the U.S. National Institute for Occupational Safety and Health (NIOSH) Total Worker Health® (TWH) initiative, some employers have created workplace wellness initiatives and programs. While these efforts are quite laudable, it is unclear to what extent, if any, safety professionals are involved in developing or operating TWH-related programs. Involvement with a wellness program carries with it certain sensitivities and risks. To gain a better sense of the level of safety professional involvement with workplace TWH-related programs, this research project was implemented to: Ascertain the prevalence of the safety professionals’ knowledge of wellness programs in general and specifically the TWH initiative; Establish what level of involvement, if any, safety professionals have with their institutions’ workplace wellness programs; Identify training or credentialing safety professionals have, if any, in wellness topics; and Examine the associations between outcomes (knowledge, involvement and competency level) and selected covariates/determinants (age, gender, smoking status, ethnicity, self-reported health, years of work experience, years of experience in safety, years of experience in wellness, field of work and number of employees at place of employment). We administered a web-based survey emailed to 5150 ASSE members during the fall of 2017. We received completed surveys from 654 responders (12.7%). Results showed that the majority of safety professionals (73%) are not familiar with the TWH program, but 78% reporting their company having a workplace wellness program. Safety professionals do implement and train in some of the topics covered in TWH. The main correlates of TWH knowledge were being female (aOR 1.49, 95%CI:1.02-2.16), African-American (aOR 3.33, 95%CI: 1.53-7.23) and having years of experience in wellness. Increasing years of experience in wellness was also a positive determinant for involvement with their institution’s workplace wellness program and having prior training in TWH topics, with adjusted odds ratios ranging from 3.5 to 35.5. Poor self-rated health was inversely associated with knowledge of TWH (aOR 0.44, 95%CI: 0.22-0.89). Company size was inversely associated with the likelihood that a safety professional is familiar with TWH. Only 284 (43.4%) of safety professionals reported receiving training in wellness topics. With these low rates of knowledge and training in TWH, increased awareness is needed. Safety professionals’ involvement with TWH is moderately high for traditional safety topics, but low in other areas. Training opportunities in TWH are minimal and credentialing is non existent. These findings, in turn, suggest that there is an opportunity to develop educational materials and training programs specifically designed for safety professionals as well as potentially developing a credentialing program for TWH

Educating Nurses on the Use of the Bedside Mobility Assessment Tool (BMAT) to Create a Culture of Safety

Healthcare workers are more at risk for injury than workers in any other industry, the injury rate in hospitals is almost double that of the entire private sector put together (OSHA, 2013). This high rate of injury has led hospital administrators and policymakers to take a closer look at the job duties and conditions of nurses and other healthcare workers. Almost half of all healthcare worker injuries are the result of overexertion or bodily reaction, injuries that occur as a result of performing patient handling tasks. Many US states have passed laws requiring hospitals to implement Safe Patient Handling and Mobility (SPHM) programs as part of injury and illness prevention programs in order to reduce this risk of injury for workers. In California, part of the legislation requires nurses to assess patients’ mobility and determine safe ways to move, reposition, and mobilize them in order to reduce risk of injury to both patients and staff. Educating nurses on how to use a standardized tool for mobility assessment ensures consistent, high-quality care across an organization and also promotes a culture of safety. A performance improvement project focusing on a revision of Banner Health’s Bedside Mobility Assessment Tool (BMAT) and education of nurse educators, nurse managers, and shift and unit peer leaders was conducted at a 395-bed, acute care, non-profit hospital located in California’s San Francisco Bay Area. The project found an engaging, in-person educational module to be effective in terms of knowledge gain and participant satisfaction. Creating motivation amongst staff to change is an integral part of facilitating implementation of a new practice for nurses

Determination of the ΔS=1\Delta S = 1 weak Hamiltonian in the SU(4) chiral limit through topological zero-mode wave functions

A new method to determine the low-energy couplings of the $\Delta S=1$ weak Hamiltonian is presented. It relies on a matching of the topological poles in $1/m^2$ of three-point correlators of two pseudoscalar densities and a four-fermion operator, measured in lattice QCD, to the same observables computed in the $\epsilon$-regime of chiral perturbation theory. We test this method in a theory with a light charm quark, i.e. with an SU(4) flavour symmetry. Quenched numerical measurements are performed in a 2 fm box, and chiral perturbation theory predictions are worked out up to next-to-leading order. The matching of the two sides allows to determine the weak low-energy couplings in the SU(4) limit. We compare the results with a previous determination, based on three-point correlators containing two left-handed currents, and discuss the merits and drawbacks of the two procedures.Comment: 38 pages, 9 figure