Mode-matching analysis of a shielded rectangular dielectric-rod waveguide

Rectangular cross-section dielectric waveguides are widely used at millimeter wavelengths. In addition, shielded dielectric resonators having a square cross-section are often used as filter elements, however there is almost no information available on the effect of the shield. Rectangular or square dielectric waveguide is notoriously difficult to analyze, because of the singular behaviour of the fields at the corners. Most published analyses are for materials with a low dielectric constant, and do not include the effects of a shield. This paper describes a numerically efficient mode matching method for the analysis of shielded dielectric rod waveguide, which is applicable to both low and high dielectric constant materials. The effect of the shield on the propagation behaviour is studied. The shield dimensions may be selected such that the shield has a negligible effect, so that results can be compared with free space data. The results are verified by comparison with several sets of published data, and have been confirmed by measurement for a nominal 'e' r of 37.4

Comparison of electric dipole moments and the Large Hadron Collider for probing CP violation in triple boson vertices

CP violation from physics beyond the Standard Model may reside in triple boson vertices of the electroweak theory. We review the effective theory description and discuss how CP violating contributions to these vertices might be discerned by electric dipole moments (EDM) or diboson production at the Large Hadron Collider (LHC). Despite triple boson CP violating interactions entering EDMs only at the two-loop level, we find that EDM experiments are generally more powerful than the diboson processes. To give example to these general considerations we perform the comparison between EDMs and collider observables within supersymmetric theories that have heavy sfermions, such that substantive EDMs at the one-loop level are disallowed. EDMs generally remain more powerful probes, and next-generation EDM experiments may surpass even the most optimistic assumptions for LHC sensitivities.Comment: 26 pages, 14 figures, published version with more argument

Survey of vector-like fermion extensions of the Standard Model and their phenomenological implications

With the renewed interest in vector-like fermion extensions of the Standard Model, we present here a study of multiple vector-like theories and their phenomenological implications. Our focus is mostly on minimal flavor conserving theories that couple the vector-like fermions to the SM gauge fields and mix only weakly with SM fermions so as to avoid flavor problems. We present calculations for precision electroweak and vector-like state decays, which are needed to investigate compatibility with currently known data. We investigate the impact of vector-like fermions on Higgs boson production and decay, including loop contributions, in a wide variety of vector-like extensions and their parameter spaces.Comment: 43 pages, 17 figures; v2: text modified to improve readability, references added, journal versio

An Assessment of Clinical Wound Evaluation Scales

Objective : To compare 2 clinical wound scales and to determine a minimal clinically important difference (MCID) on the visual analog cosmesis scale. Methods : Using data from 2 previously published clinical trials, 91 lacerations and 43 surgical incisions were assessed on the 2 scales; a 100-mm visual analog scale (VAS) (0 = worst possible scar, 100 = best possible scar) and a wound evaluation scale (WES) assessing 6 clinical variables (a score of 6 is considered optimal, while a score of ≤5 suboptimal). All wound assessments on the VAS were done by 2 cosmetic surgeons who rated photographs on 2 occasions. A cohort of wounds on the WES were assessed by a second observer. The difference of the mean optimal and suboptimal VAS scores for each study was used to determine a MCID on the VAS scale. Results : The VAS scale yielded intraobserver agreements of 0.93 and 0.87 (95% CI: 0.89–0.96 and 0.78–0.93) and interobserver agreements of 0.50 and 0.71 (95% CI: 0.32–0.65 and 0.52–0.84) for lacerations and incisions, respectively. Kappa coefficient measuring agreement on the WES was 0.79 (95% CI: 0.57–1.0). The mean (±SD) VAS scores of optimal wounds were 72 ± 12 mm and 65 ± 20 mm, while the mean scores of suboptimal wounds were 57 ± 17 mm and 50 ± 23 mm for lacerations and incisions, respectively. Conclusions : An MCID on the VAS cosmesis scale is 15 mm. Studies should be designed to have a sample size and power to detect this difference.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75496/1/j.1553-2712.1998.tb02465.x.pd

Cosmic Strings from Supersymmetric Flat Directions

Flat directions are a generic feature of the scalar potential in supersymmetric gauge field theories. They can arise, for example, from D-terms associated with an extra abelian gauge symmetry. Even when supersymmetry is broken softly, there often remain directions in the scalar field space along which the potential is almost flat. Upon breaking a gauge symmetry along one of these almost flat directions, cosmic strings may form. Relative to the standard cosmic string picture based on the abelian Higgs model, these flat-direction cosmic strings have the extreme Type-I properties of a thin gauge core surrounded by a much wider scalar field profile. We perform a comprehensive study of the microscopic, macroscopic, and observational characteristics of this class of strings. We find many differences from the standard string scenario, including stable higher winding mode strings, the dynamical formation of higher mode strings from lower ones, and a resultant multi-tension scaling string network in the early universe. These strings are only moderately constrained by current observations, and their gravitational wave signatures may be detectable at future gravity wave detectors. Furthermore, there is the interesting but speculative prospect that the decays of cosmic string loops in the early universe could be a source of ultra-high energy cosmic rays or non-thermal dark matter. We also compare the observational signatures of flat-direction cosmic strings with those of ordinary cosmic strings as well as (p,q) cosmic strings motivated by superstring theory.Comment: 58 pages, 16 figures, v2. accepted to PRD, added comments about baryogenesis and boosted decay products from cusp annihilatio