Numerical equation of state and other scaling functions from an improved three-dimensional Ising model

We study an improved three-dimensional Ising model with external magnetic field near the critical point by Monte Carlo simulations. From our data we determine numerically the universal scaling functions of the magnetization, that is the equation of state, of the susceptibility and of the correlation length. In order to normalize the scaling functions we calculate the critical amplitudes of the three observables on the critical line, the phase boundary and the critical isochore. These amplitudes lead to the universal ratios C^+/C^-=4.756(28), R_{chi}=1.723(13), Q_c=0.326(3) and Q_2=1.201(10). We find excellent agreement of the data with the parametric representation of the asymptotic equation of state as found by field theory methods. The comparison of the susceptibility data to the corresponding scaling function shows a marginal difference in the symmetric phase, which can be explained by the slightly different value for R_{chi} used in the parametrization. The shape of the correlation-length-scaling function is similar to the one of the susceptibility, as expected from earlier parametrizations. The peak positions of the two scaling functions are coinciding within the error bars.Comment: 27 pages, 14 Ps-figures, Latex2e, 10 pages added, including the scaling function of the correlation length, to appear in Nucl. Phys.

Top transport in electroweak baryogenesis

In non-supersymmetric models of electroweak baryogenesis the top quark plays a crucial role. Its CP-violating source term can be calculated in the WKB approximation. We point out how to resolve certain discrepancies between computations starting from the Dirac equation and the Schwinger--Keldysh formalism. We also improve on the transport equations, keeping the W-scatterings at finite rate. We apply these results to a model with one Higgs doublet, augmented by dimension-6 operators, where our refinements lead to an increase in the baryon asymmetry by a factor of up to about 5.Comment: 17 pages, 3 figures, references adde

External field dependence of the correlation lengths in the three-dimensional O(4) model

We investigate numerically the transverse and longitudinal correlation lengths of the three-dimensional O(4) model as a function of the external field H. In the low-temperature phase we verify explicitly the H^{-1/2}-dependence of the transverse correlation length, which is expected due to the Goldstone modes of the model. On the critical line we find the universal amplitude ratio xi^c_T / xi^c_L = 1.99(1). From our data we derive the universal scaling function for the transverse correlation length. The H-dependencies of the correlation lengths in the high temperature phase are discussed and shown to be in accord with the scaling functions.Comment: 3 pages, 4 figures, Lattice2003(higgs) contribution, espcrc2.st

Mode-converted Lamb wave sensitivity prediction for part-thickness crack-like defects

Fatigue crack growth is one of the most common damage types in aluminum components, widely used in aircraft structures. Detection of fatigue cracks at an early stage is important to guarantee aircraft safety. Efficient non-destructive evaluation (NDE) and structural health monitoring (SHM) can be achieved by employing low frequency guided ultrasonic waves, as they can propagate long distances along plate structures. SHM systems using distributed guided waves sensors have been proposed for efficient monitoring, but have limitations due to environmental influences such as the temperature stability of the conventional baseline subtraction method. The scattering and mode conversion of guided waves at part-thickness defects was investigated to quantify the sensitivity for defect detection and the potential for the development of a baseline-free SHM methodology employing mode converted guided waves. Baseline-free SHM methodology employing mode conversion is expected to overcome some of the limitations caused by environmental factors and to improve sensitivity and stability by employing new or modified signal processing algorithms. A three dimensional (3D) Finite Element (FE) model was developed to predict the mode conversion of the fundamental guided wave modes. The influence of defect length and depth on detection results were investigated numerically. The detection sensitivity for part-thickness defects in a plate is quantified

Guided wave scattering analysis around a circular delamination in a quasi-isotropic fiber-composite laminate

Carbon fiber reinforced composites are widely used in the aerospace industry, but barely visible impact damage can lead to delamination and compromise the structural integrity. The scattering of the fundamental anti-symmetric guided wave mode (A0 Lamb mode) at an artificial circular delamination in a quasi-isotropic laminate was investigated experimentally. A 5 cycle Hanning windowed wave pulse was used as the excitation signal for the experiments. Fast Fourier Transform was employed to identify the guided wave amplitude of the scattered field along various directions. The experimental wavefield was captured using a laser Doppler vibrometer. Experimental results are presented for the scattering pattern and scattering amplitude as a function of distance from the damage. The results of this study can help to improve delamination detection techniques using guided waves and to gain physical insights into the scattering of guided waves at a delamination

Baryogenesis in the Two-Higgs Doublet Model

We consider the generation of the baryon asymmetry in the two-Higgs doublet model. Investigating the thermal potential in the presence of CP violation, as relevant for baryogenesis, we find a strong first-order phase transition if the extra Higgs states are heavier than about 300 GeV. The mass of the lightest Higgs can be as large as about 200 GeV. We compute the bubble wall properties, including the profile of the relative complex phase between the two Higgs vevs. The baryon asymmetry is generated by top transport, which we treat in the WKB approximation. We find a baryon asymmetry consistent with observations. The neutron electric dipole moment is predicted to be larger than about 10^{-27}ecm and can reach the current experimental bound. Low values of tan\beta are favored.Comment: 25 pages, 7 figure

Electroweak Baryogenesis with dimension-6 Higgs interactions

We present the computation of the baryon asymmetry in the SM amplified by dimension-6 Higgs interactions using the WKB approximation. Analyzing the one-loop potential it turns out that the phase transition is strongly first order in a wide range of the parameters. It is ensured not to wash out the net baryon number gained previously even for Higgs masses up to at least 170 GeV. In addition dimension-6 operators induce new sources of CP violation. Novel source terms which enhance the generated baryon asymmetry emerge in the transport equations. This model predicts a baryon to entropy ratio close to the observed value for a large part of the parameter space.Comment: 10 pages, 4 figures, Talk given at the 8th International Moscow School of Physic

THE EFFECTS OF ANKLE BRACING ON SPORTS-SPECIFIC CAPABILITIES

INTRODUCTION Ankle braces are widely used in athletes. In some professional sports leagues it is mandatory to wear ankle braces in order to get insurance. Even prophylactic bracing is often used in normal sports. The efficiency of ankle joint orthoses was already demonstrated in several studies, and different types of external stabilization devices were compared. Especially the. aspects of mechanical stabilization were discussed in these studies as well as retrospective observations of the prophylactic benefit regarding the prevention of sprains by using orthoses. Neurophysiological or psychological aspects are hardly taken into consideration in the literature when evaluating different types of orthoses. In the presented study the proprioception with regard to the ankle joint and especially its influence by orthoses and the effect of ankle braces on sports- specific capabilities will be discussed. First of all the question is, whether the orthoses have an impact on the proprioception of the ankle joint at all. If there is an influence, then it is of particular importance for a comprehensive judgement to document the degree of influence by each type of orthoses for the injured and not injured ankle joint. By evaluating the results of this study a possible reduction of the proprioception caused by ankle sprains will be investigated as well. This phenomenon of a posttraumatic proprioceptive deficit was already described and controversially discussed in the literature. MATERIALS AND METHODS The influence of four stabilizing devices (aircast brace, . ligafix air-brace, malleoloc-brace, taping) on sportsspecific capabilities and propioceptivity of stable and unstable ankle joints were assessed. Therefore both ankle joints of 18 uninjured volunteers and 23 injured volunteers with an old ankle sprain were tested with two different set-ups (modified Japan-test, 5 point single leg jump test). We used a modular coordination-testsystem with 5 contact plates and a computer monitor that gives in randomised sequence the signal which circles of the 5 plates to jump on. RESULTS The time for both tests as well as reaction time and contact time for each moving direction was measured and calculated by a software program. Regarding the modified Japan-test and the 5 point single leg jump test the injured group achieved showed significant better results (p< 0.01) & (

EFFECT OF DIFFERENT LOW BACK TRAINING PROGRAMS ON LUMBAR SPINE KINESTHESIA

Reduced kinesthetic perceptions can impair lower back sensorimotor functions and result in increased injury risk. The effect of low back training programs on lumbar spine kinesthetic sensibility is undetermined. There was a back strengthening exercise group (with low back pain; training 4.4 h/wk), a “classical” back training program group (with low back pain; training 4.9 h/wk) and a control group (training 5.4 h/wk). During an active reproduction test, subjects performed trunk positions in random order: flexion [A(0°-20°), B(20°-40°)], lateral flexion [C(0°-30°)], Using a 3D-ultrasound motion analysis system the repositioning error was calculated from the given target position to the subject perceived target position, before and after a 5 week training period. Results show decreased repositioning error after the training for both training groups

Composite impact damage detection and characterization using ultrasound and X-ray NDE techniques

Combining low weight and high strength, carbon fiber reinforced composites are widely used in the aerospace industry, including for primary aircraft structures. Barely visible impact damage can compromise the structural integrity and potentially lead to failures. Edge Illumination (EI) X-ray Phase Contrast imaging (XPCi) is a novel X-ray imaging technique that uses the phase effects induced by damage to create improved contrast. For a small cross-ply composite specimen with impact damage, damage detection was compared to ultrasonic immersion C-scans. Different defect types could be located and identified, verified from the conventional ultrasonic NDE measurement