Product Integral Representations of Wilson Lines and Wilson Loops, and Non-Abelian Stokes Theorem

We make use of product integrals to provide an unambiguous mathematical representation of Wilson line and Wilson loop operators. Then, drawing upon various properties of product integrals, we discuss such properties of these operators as approximating them with partial sums, their convergence, and their behavior under gauge transformations. We also obtain a surface product integral representation for the Wilson loop operator. The result can be interpreted as the non-abelian version of Stokes theorem.Comment: 20 pages, LaTe

OPTIS - a satellite-based test of Special and General Relativity

A new satellite based test of Special and General Relativity is proposed. For the Michelson-Morley experiment we expect an improvement of at least three orders of magnitude, and for the Kennedy-Thorndike experiment an improvement of more than one order of magnitude. Furthermore, an improvement by two orders of the test of the universality of the gravitational red shift by comparison of an atomic clock with an optical clock is projected. The tests are based on ultrastable optical cavities, an atomic clock and a comb generator.Comment: To appear in Class. Quantum Gra

Limits on the Time Evolution of Space Dimensions from Newton's Constant

Limits are imposed upon the possible rate of change of extra spatial dimensions in a decrumpling model Universe with time variable spatial dimensions (TVSD) by considering the time variation of (1+3)-dimensional Newton's constant. Previous studies on the time variation of (1+3)-dimensional Newton's constant in TVSD theory had not been included the effects of the volume of the extra dimensions and the effects of the surface area of the unit sphere in D-space dimensions. Our main result is that the absolute value of the present rate of change of spatial dimensions to be less than about 10^{-14}yr^{-1}. Our results would appear to provide a prima facie case for ruling the TVSD model out. We show that based on observational bounds on the present-day variation of Newton's constant, one would have to conclude that the spatial dimension of the Universe when the Universe was at the Planck scale to be less than or equal to 3.09. If the dimension of space when the Universe was at the Planck scale is constrained to be fractional and very close to 3, then the whole edifice of TVSD model loses credibility.Comment: 22 pages, accepted for publication in Int.J.Mod.Phys.

An Investigation of the Divergences and Convergences of Trait Empathy across Two Cultures

The extent to which individuals with a variety of cultural backgrounds differ in empathic responsiveness is unknown. This paper describes the differences in trait empathy in one independent and one interdependent society (i.e., United States and Iran respectively). The analysis of data collected from self-reported questionnaires answered by 326 adults indicated a significant difference in the cognitive component of empathy concerning participants’ affiliation to either egocentric or socio-centric society: Iranian participants with interdependent cultural norms, reported higher cognitive empathy compared to American participants who share independent cultural norms. In line with previous studies, gender differences were observed in all subscales of questionnaires except the Empathy Quotient. Female participants demonstrated more empathy than males in both samples. Implications for understanding the cross-cultural differences of various components of empathy are discussed

Quantum Tests of the Foundations of General Relativity

The role of the equivalence principle in the context of non-relativistic quantum mechanics and matter wave interferometry, especially atom beam interferometry, will be discussed. A generalised form of the weak equivalence principle which is capable of covering quantum phenomena too, will be proposed. It is shown that this generalised equivalence principle is valid for matter wave interferometry and for the dynamics of expectation values. In addition, the use of this equivalence principle makes it possible to determine the structure of the interaction of quantum systems with gravitational and inertial fields. It is also shown that the path of the mean value of the position operator in the case of gravitational interaction does fulfill this generalised equivalence principle.Comment: Classical and Quantum Gravity 15, 13 (1998

Factors associated with the efficacy of polyp detection during routine flexible sigmoidoscopy

Objective: Flexible sigmoidoscopy reduces the incidence of colonic cancer through the detection and removal of premalignant adenomas. However, the efficacy of the procedure is variable. The aim of the present study was to examine factors associated with the efficacy of detecting polyps during flexible sigmoidoscopy. Design and patients: Retrospective observational cohort study of all individuals undergoing routine flexible sigmoidoscopy in NHS Greater Glasgow and Clyde from January 2013 to January 2016. Results: A total of 7713 patients were included. Median age was 52 years and 50% were male. Polyps were detected in 1172 (13%) patients. On multivariate analysis, increasing age (OR 1.020 (1.016–1.023) p<0.001), male sex (OR 1.23 (1.10–1.38) p<0.001) and the use of any bowel preparation (OR 3.55 (1.47–8.57) p<0.001) were associated with increasing numbers of polyps being detected. There was no significant difference in the number of polyps found in patients who had received an oral laxative preparation compared with an enema (OR 3.81 (1.57–9.22) vs 3.45 (1.43–8.34)), or in those who received sedation versus those who had not (OR 1.00 vs 1.04 (0.91–1.17) p=0.591). Furthermore, the highest number of polyps was found when the sigmoidoscope was inserted to the descending colon (OR 1.30 (1.04–1.63)). Conclusions: Increasing age, male sex and the utilisation of any bowel preparation were associated with an increased polyp detection rate. However, the use of sedation or oral laxative preparation appears to confer no additional benefit. In addition, the results indicate that insertion to the descending colon optimises the efficacy of flexible sigmoidoscopy polyp detection

A New Limit on Signals of Lorentz Violation in Electrodynamics

We describe the results of an experiment to test for spacetime anisotropy terms that might exist from Lorentz violations. The apparatus consists of a pair of cylindrical superconducting cavity-stabilized oscillators operating in the TM_{010} mode with one axis east-west and the other vertical. Spatial anisotropy is detected by monitoring the beat frequency at the sidereal rate and its first harmonic. We see no anisotropy to a part in 10^{13}. This puts a comparable bound on four linear combinations of parameters in the general Standard Model extension, and a weaker bound of <4 x 10^{-9} on three others.Comment: 4 pages, 3 figures, 2 table

Radiation from the LTB black hole

Does a dynamical black hole embedded in a cosmological FRW background emit Hawking radiation where a globally defined event horizon does not exist? What are the differences to the Schwarzschild black hole? What about the first law of black hole mechanics? We face these questions using the LTB cosmological black hole model recently published. Using the Hamilton-Jacobi and radial null geodesic-methods suitable for dynamical cases, we show that it is the apparent horizon which contributes to the Hawking radiation and not the event horizon. The Hawking temperature is calculated using the two different methods giving the same result. The first law of LTB black hole dynamics and the thermal character of the radiation is also dealt with.Comment: 9 pages, revised version, Europhysics Letter 2012 97 2900

Collaborative relationships between logistics service providers and humanitarian organizations during disaster relief operations

Purpose: this study explores barriers and benefits of establishing relationships between humanitarian organizations (HOs) and logistics service providers (LSPs) in order to improve humanitarian disaster relief operations (DROs). the perceptions of a variety of actors are explored to determine key factors which influence collaboration. Design/ methodology/ approach: This study comprises of quantitative methodological approaches. a comprehensive literature review was undertaken alongside an online survey with a variety of respondents. descriptive statistics, data visualization and qualitative data analysis were implemented to analyse survey results. a follow-up survey and interviews with LSPs validated the results. Findings, the research presents the opinions of a variety of actors involved in DROs and reveals barriers which affect HO/LSP collaboration. explanations for these barriers and possible solutions to mitigate them are disclosed. the findings also uncover gaps between research and practice; providing new insights into behaviour in the humanitarian field. Practical implications: We provide an in-depth understanding of the barriers and challenges faced in this field and suggest a revaluation of corporate decision making in order to increase trust between LSPs and HOs. We identify future research topics including the impact of donors and military organisations on HO decision making, and analysis of variables which may affect the formation of collaborative partnerships. Originality/value: We introduce a unique empirical insight into the perspective of HOs, LSPs and academics and offers suggestions for mitigating the numerous barriers associated with successful collaborative partnerships between HOs and LSPs

Quantum-gravity-motivated Lorentz-symmetry tests with laser interferometers

We consider the implications for laser interferometry of the quantum-gravity-motivated modifications in the laws of particle propagation, which are presently being considered in attempts to explain puzzling observations of ultra-high-energy cosmic rays. We show that there are interferometric setups in which the Planck-scale effect on propagation leads to a characteristic signature. A naive estimate is encouraging with respect to the possibility of achieving Planck-scale sensitivity, but we also point out some severe technological challenges which would have to be overcome in order to achieve this sensitivity.Comment: 17 pages, 3 figure