Impact of Neutron Decay Experiments on non-Standard Model Physics

This paper gives a brief overview of the present and expected future limits on physics beyond the Standard Model (SM) from neutron beta decay, which is described by two parameters only within the SM. Since more than two observables are accessible, the problem is over-determined. Thus, precise measurements of correlations in neutron decay can be used to study the SM as well to search for evidence of possible extensions to it. Of particular interest in this context are the search for right-handed currents or for scalar and tensor interactions. Precision measurements of neutron decay observables address important open questions of particle physics and cosmology, and are generally complementary to direct searches for new physics beyond the SM in high-energy physics. Free neutron decay is therefore a very active field, with a number of new measurements underway worldwide. We present the impact of recent developments.Comment: 13 pages, 6 figures; Proceedings of the 5th International BEYOND 2010 Conference, Cape Town, South Africa (2010), World Scientific, accepted for publication; Corrected typo

Quasi-Periodic Oscillations in Short Recurring Bursts of the magnetars SGR 1806-20 and SGR 1900+14 Observed With RXTE

Quasi-periodic oscillations (QPOs) observed in the giant flares of magnetars are of particular interest due to their potential to open up a window into the neutron star interior via neutron star asteroseismology. However, only three giant flares have been observed. We therefore make use of the much larger data set of shorter, less energetic recurrent bursts. Here, we report on a search for QPOs in a large data set of bursts from the two most burst-active magnetars, SGR 1806-20 and SGR 1900+14, observed with the Rossi X-ray Timing Explorer (RXTE). We find a single detection in an averaged periodogram comprising 30 bursts from SGR 1806-20, with a frequency of 57 Hz and a width of 5 Hz, remarkably similar to a giant flare QPO observed from SGR 1900+14. This QPO fits naturally within the framework of global magneto-elastic torsional oscillations employed to explain the giant flare QPOs. Additionally, we uncover a limit on the applicability of Fourier analysis for light curves with low background count rates and strong variability on short timescales. In this regime, standard Fourier methodology and more sophisticated Fourier analyses fail in equal parts by yielding an unacceptably large number of false positive detections. This problem is not straightforward to solve in the Fourier domain. Instead, we show how simulations of light curves can offer a viable solution for QPO searches in these light curves.Comment: accepted for publication in ApJ; 12 pages, 7 figures; code + instructions at https://github.com/dhuppenkothen/MagnetarQPOSearchPaper ; associated data products at http://figshare.com/articles/SGR_1900_14_RXTE_Data/1184101 (SGR 1900+14) and http://figshare.com/articles/SGR_1806_20_Bursts_RXTE_data_set/1184427 (SGR 1806-20

Dispersion of longitudinal momentum distributions induced in fragmentation reactions

On the basis of systematic measurements of fragmentation reactions, which provide a detailed overview on the velocity distributions of residual nuclei, an improved description of the kinematical properties of the fragmentation residues is established. This work is dedicated to the fluctuations of their momentum distributions. In contrast to previous investigations, limited to close-to-projectile fragments, we extended our study to the entire production range, down to the lightest observed fragments. In this context, beside the contribution of abrasion and evaporation processes, we considered the effect of the thermal break-up on the width of the momentum distributions. Using approximated theoretical descriptions of the different reaction stages, a new analytical formula for the variance of the momentum distribution is derived, which is well adapted to technical applications.Comment: 14 pages, 3 figures, background info. at http://www-wnt.gsi.de/charms

Xenogeneic, extracorporeal liver perfusion in primates improves the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio)

In fulminant hepatic failure (FHF), the development of hepatic encephalopathy is associated with grossly abnormal concentrations of plasma amino acids (PAA). Normalization of the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio) correlates with clinical improvement. This study evaluated changes in PAA metabolism during 4 h of isolated, normothermic extracorporeal liver perfusion using a newly designed system containing human blood and a rhesus monkey liver. Bile and urea production were within the physiological range. Release of the transaminases AST, ALT and LDH were minimal. The ratio of branched (valine, leucine, isoleucine) to aromatic (tyrosine, phenylalanine) amino acids increased significantly. These results indicate that a xenogeneic extracorporeal liver perfusion system is capable of significantly increasing Fischer's ratio and may play a role in treating and bridging patients in FHF in the future

Telescopic actions

A group action H on X is called "telescopic" if for any finitely presented group G, there exists a subgroup H' in H such that G is isomorphic to the fundamental group of X/H'. We construct examples of telescopic actions on some CAT[-1] spaces, in particular on 3 and 4-dimensional hyperbolic spaces. As applications we give new proofs of the following statements: (1) Aitchison's theorem: Every finitely presented group G can appear as the fundamental group of M/J, where M is a compact 3-manifold and J is an involution which has only isolated fixed points; (2) Taubes' theorem: Every finitely presented group G can appear as the fundamental group of a compact complex 3-manifold.Comment: +higher dimension

Modelling and simulation of fluid-structure interactions in human snoring

Snoring noise is generated by vibration of the soft tissues of the upper airway, principally those that form the back of the roof of the mouth (the soft palate) and its conical extension (the uvula). In addition to discord with bed partners, snorers are at much greater risk of obstructive sleep apnoea. This sleep-related breathing disorder is characterised by episodic upper airway obstruction with accompanying sleep disruption and consequent excessive daytime sleepiness, as well as an elevated risk of accidents and cardiovascular disease. The instability that leads to flow-induced oscillations characteristic of inspiratory snoring in the human upper airway may be modelled using a cantilevered flexible plate in a mean channel flow. However, the cantilever in existing models strictly only captures the dynamics of the uvula. In a more complete model, these dynamics will be augmented by their interaction with the motions of the soft palate—itself a flexible structure of higher effective stiffness—from which the uvula extends. To investigate how the elasticity of the soft palate affects uvula motion and their combined susceptibility to flow-induced oscillation a modification is made to the standard model. In a one-dimensional cantilevered flexible plate we allow thickness to vary as a function of length, thus effecting local changes in inertia and flexural rigidity.The overall cantilever therefore comprises a section representing the soft palate followed by a section of lower thickness that represents the uvula. The cantilever is attached to a rigid wall (hard palate) separating upper (nasal) and lower (oral) inlets of a rigid-walled channel (pharynx) conveying a viscous flow. This model is formulated using the open-source finite-element software library oomph-lib. A parametric study is performed in which the uvula-to-soft palate length and thickness ratios are varied whilst keeping their combined length constant. Results show that there is a critical uvula-length fraction that determines whether the uvula stabilises or destabilises the system. A relatively ‘short’ uvula swings out of phase with the soft palate and these oscillations are observed to decay; the mode shapes involved are not predicted by a uniform-thickness plate model. By contrast, if the uvula is relatively ‘long’ the flexible plate motion is isolated to the uvular section and the oscillations grow in amplitude, indicating a net energy transfer from fluid to structure. Increasing the thickness, hence inertia and flexural rigidity, of a ‘short’ uvula, e.g., by oedema, makes the fluid-structure system more unstable. In this case if the oedema were aggrevated by the vibratory mechanical insult then it would be self-sustaining and imply a bidirectional relationship between snoring and oedema of the uvula.Anatomical variability is common in the lengths of the soft palate and uvula which may make some people more susceptible than others to uvulopalatal snoring. Palatal surgery for snoring has proved highly variable in its effectiveness. Modelling of palatal motion using this approach may help guide patient selection for and type of soft-palate surgery applied to treat this common and potentially disabling condition

Characterizing the metabolic intensity and cardiovascular demands of walking football in Southeast Asian women

Given that the recent rise in obesity rates throughout Southeast Asia is disproportionately driven by women, part of the regional solution may be to encourage more habitual physical activity within this population. Taking advantage of the regional popularity of walking football, this study sought to characterize the cardiovascular demands and metabolic intensity of Southeast Asian women competing in walking football matches to determine the sports’ suitability for promoting physical health. It was hypothesized that both cardiovascular and metabolic intensity measures (≥65% HR% and ≥3.0 METs, respectively) would meet or exceed established thresholds for improving fitness and health. Methods: Women’s teams from Singapore (Mean±SD: 42±11 yrs age; 29.2±7.0 kg/m2 BMI; n=14) and Malaysia (40±10 yrs age; 32.9±5.7 kg/m2 BMI; n=8) competed in two successive matches within a single day during which measures of heart rate (HR) and GPS (from portable handheld device) were recorded for each player, while relative HR was computed as a percent of each player’s age-predicted maximal HR (HR%, %). The GPS data were later converted to walking distance and metabolic intensity (i.e., metabolic equivalents, or METs). One-sample t-tests at the 0.05 alpha level were used to compare variables to their respective thresholds. Results: Both Malaysian and Singaporean teams had mean relative HRs (91-95% of HRMAX [P=0.008] versus 77-80% of HRMAX [