Lattice QCD with light dynamical quarks

We report on the simulation of QCD with light dynamical quarks using the two-step multi-boson (TSMB) algorithm. In an exploratory study with two flavours of quarks at lattice spacing about 0.27 fm and with quark mass down to one sixth of the strange quark mass eigenvalue spectra and autocorrelations have been studied. Here we present results on the volume dependence as well as tests of possible algorithmic improvements.Comment: 6 pages, Lattice2002(spectrum

Numerical simulation tests with light dynamical quarks

Two degenerate flavours of quarks are simulated with small masses down to about one fifth of the strange quark mass by using the two-step multi-boson (TSMB) algorithm. The lattice size is 8^3 x 16 with lattice spacing about 0.27fm which is not far from the N_t=4 thermodynamical cross-over line. Autocorrelations of different physical quantities are estimated as a function of the quark mass. The eigenvalue spectra of the Wilson-Dirac operator are investigated.Comment: 14 pages, 7 figures, uses svjour.cls; mistake in the autocorrelation of the pion mass corrected, version accepted for publication on Eur. Phys. J.

Mechanical performance and corrosion behaviour of Zr-based bulk metallic glass produced by selective laser melting

Nearly fully dense, glassy Zr52.5Cu17.9Ni14.6Al10Ti5 bulk specimens were fabricated by selective laser melting (SLM) and their behaviour during compressive loading, during wear testing and in a corrosive medium was investigated. Their performance was compared with as-cast material of the same composition. The additively manufactured samples exhibit a yield strength around 1700 MPa combined with a plastic strain of about 0.5% after yielding despite the residual porosity of 1.3%, which is distributed uniformly in the samples. The propagation of shear bands in the bulk metallic glass prepared by SLM was studied. The specific wear rate and the worn surfaces demonstrated that similar wear mechanisms are active in the SLM and the as-cast samples. Hence, manufacturing the glass in layers does not adversely affect the wear properties. The same holds for the corrosion tests, which were carried out in 0.01 M Na2SO4 and 0.1 M NaCl electrolyte. The anodic polarization curves of SLM samples and as-cast samples revealed a similar corrosion behaviour. However, the SLM samples have a slightly reduced susceptibility to pitting corrosion and exhibit an improved surface healing ability, which might be attributed to an improved homogeneity of the additively manufactured glass

Signatures of partition functions and their complexity reduction through the KP II equation

A statistical amoeba arises from a real-valued partition function when the positivity condition for pre-exponential terms is relaxed, and families of signatures are taken into account. This notion lets us explore special types of constraints when we focus on those signatures that preserve particular properties. Specifically, we look at sums of determinantal type, and main attention is paid to a distinguished class of soliton solutions of the Kadomtsev-Petviashvili (KP) II equation. A characterization of the signatures preserving the determinantal form, as well as the signatures compatible with the KP II equation, is provided: both of them are reduced to choices of signs for columns and rows of a coefficient matrix, and they satisfy the whole KP hierarchy. Interpretations in term of information-theoretic properties, geometric characteristics, and the relation with tropical limits are discussed.Comment: 42 pages, 11 figures. Section 7.1 has been added, the organization of the paper has been change

Time Course Change of Muscle Thickness of the Tibialis Anterior Following Blood Flow Restricted Training

Traditional resistance training programs recommend training loads of at least 60% 1-repetition maximum (1RM) to stimulate muscle hypertrophy within 3 weeks. Low-load blood flow restricted (BFR) resistance training (RT) has implications in rehabilitation since this modality has shown comparable muscle hypertrophy to high-load RT at intensities as low as 30% 1RM. However, the recommended effects of BFR on muscle size in various musculature throughout an intervention has not been thoroughly examined. PURPOSE: Therefore, the purpose of this investigation is to measure temporal changes in muscle thickness (MT) on the tibialis anterior (TA) throughout 4 weeks of BFR training. METHODS: Thirteen untrained participants were randomized into two groups: (BFR; n=8) (177.6 ± 4.1 cm, 84.8 ± 15.1 kg, 21.3 ± 1 years) or control non-BFR (n=5) (172.6 ± 8.2 cm, 76.7 ± 11.1 kg, 23.4 ± 2.7 years) who were matched for training sessions, sets, and reps. During the 4-week period (8 sessions), participants underwent twice-weekly sessions of unilateral isokinetic dorsiflexion training at 30% of their daily peak torque at a velocity of 60°/s with or without BFR. Ultrasound-derived measures of muscle thickness were captured at one-third the distance from the fibular head to the medial malleolus prior to the pre- and post-intervention testing sessions. Two separate linear regression analyses were used to examine group slope differences in MT across all training sessions. RESULTS: Linear regression analyses indicated that the control (i.e., non-BFR) exhibited a significant, positive (b = 0.023, SE = 0.01, r2=0.626, p=0.006) increase in MT from pre- to post testing. However, there was no significant change (b=0.021, SE = 0.01, r2=0.324, p=0.086) in MT across Time for the BFR group. CONCLUSION: Low-load RT without BFR induces temporal changes in muscle size following a short 4-week intervention. This exemplifies the efficacy of low-load training in inducing detectible changes in muscle thickness of the TA, and does not indicate BFR has an additive effect on temporal changes in muscle size of novice males following a 4-week intervention

Partially quenched chiral perturbation theory and numerical simulations

The dependence of the pseudoscalar meson mass and decay constant is compared to one-loop Partially Quenched Chiral Perturbation Theory (PQChPT) in a numerical simulation with two light dynamical quarks. The characteristic behaviour with chiral logarithms is observed. The values of the fitted PQChPT-parameters are in a range close to the expectation in continuum in spite of the fact that the lattice spacing is still large, namely a=0.28 fm.Comment: 11 pages, 3 figures; discussion of the results in section 3 extende

Oriented Matroids -- Combinatorial Structures Underlying Loop Quantum Gravity

We analyze combinatorial structures which play a central role in determining spectral properties of the volume operator in loop quantum gravity (LQG). These structures encode geometrical information of the embedding of arbitrary valence vertices of a graph in 3-dimensional Riemannian space, and can be represented by sign strings containing relative orientations of embedded edges. We demonstrate that these signature factors are a special representation of the general mathematical concept of an oriented matroid. Moreover, we show that oriented matroids can also be used to describe the topology (connectedness) of directed graphs. Hence the mathematical methods developed for oriented matroids can be applied to the difficult combinatorics of embedded graphs underlying the construction of LQG. As a first application we revisit the analysis of [4-5], and find that enumeration of all possible sign configurations used there is equivalent to enumerating all realizable oriented matroids of rank 3, and thus can be greatly simplified. We find that for 7-valent vertices having no coplanar triples of edge tangents, the smallest non-zero eigenvalue of the volume spectrum does not grow as one increases the maximum spin \jmax at the vertex, for any orientation of the edge tangents. This indicates that, in contrast to the area operator, considering large \jmax does not necessarily imply large volume eigenvalues. In addition we give an outlook to possible starting points for rewriting the combinatorics of LQG in terms of oriented matroids.Comment: 43 pages, 26 figures, LaTeX. Version published in CQG. Typos corrected, presentation slightly extende

Feeding Cannabidiol (CBD)-Containing Treats Did Not Affect Canine Daily Voluntary Activity

Growing public interest in the use of cannabidiol (CBD) for companion animals has amplified the need to elucidate potential impacts. The purpose of this investigation was to determine the influence of CBD on the daily activity of adult dogs. Twenty-four dogs (18.0 ± 3.4 kg, 9 months−4 years old) of various mixed breeds were utilized in a randomized complete block design with treatments targeted at 0 and 2.5 mg (LOW) and at 5.0 mg (HIGH) CBD/kg body weight (BW) per day split between two treats administered after twice-daily exercise (0700–0900 and 1,700–1,900 h). Four hours each day [1,000–1,200 h (a.m.) and 1,330–1,530 h (p.m.)] were designated as times when no people entered the kennels, with 2 h designated as Quiet time and the other 2 h as Music time, when calming music played over speakers. Quiet and Music sessions were randomly allotted to daily a.m. or p.m. times. Activity monitors were fitted to dogs\u27 collars for continuous collection of activity data. Data were collected over a 14-day baseline period to establish the activity patterns and block dogs by activity level (high or low) before randomly assigning dogs within each block to treatments. After 7 days of treatment acclimation, activity data were collected for 14 days. Data were examined for differences using the MIXED procedure in SAS including effects of treatment, day, session (Quiet or Music), time of day (a.m. or p.m.), and accompanying interactions. CBD (LOW and HIGH) did not alter the total daily activity points (P = 0.985) or activity duration (P = 0.882). CBD tended (P = 0.071) to reduce total daily scratching compared with the control. Dogs were more active in p.m. sessions than in a.m. sessions (P \u3c 0.001). During the p.m. session, dogs receiving HIGH tended (P = 0.091) to be less active than the control (CON). During the a.m. and p.m. sessions, CBD reduced scratching compared with CON (P = 0.030). CBD did not affect the activity duration during exercise periods (P = 0.143). These results indicate that, when supplemented with up to 4.5 mg CBD/kg BW/day, CBD does not impact the daily activity of adult dogs, but may exert an antipruritic effect