Metadynamics surfing on topology barriers: the CP N 121 case

As one approaches the continuum limit, QCD systems, investigated via numerical simulations, remain trapped in sectors of field space with fixed topological charge. As a consequence the numerical studies of physical quantities may give biased results. The same is true in the case of two dimensional CPN 121 models. In this paper we show that metadynamics, when used to simulate CPN 121, allows to address efficiently this problem. By studying CP20 we show that we are able to reconstruct the free energy of the topological charge F (Q) and compute the topological susceptibility as a function of the coupling and of the volume. This is a very important physical quantity in studies of the dynamics of the \u3b8 vacuum and of the axion. This method can in principle be extended to QCD applications. \ua9 2016, The Author(s)

Possible predictors of involuntary weight loss in patients with Alzheimer's disease

Loss in body mass (∆BM) is a common feature in patients with Alzheimer's disease (AD). However, the etiology of this phenomenon is unclear. The aim of this cohort study was to observe possible ∆BM in AD patients following a standard institutionalized diet. Secondary objective was to identify possible predictors of ∆BM. To this end, 85 AD patients (age: 76±4 yrs; stature: 165±3 cm; BM: 61.6±7.4 kg; mean±standard deviation) and 86 controls (CTRL; age: 78±5 yrs; stature: 166±4 cm; BM: 61.7±6.4 kg) were followed during one year of standard institutionalized diet (~1800 kcal/24h). BM, daily energy expenditure, albuminemia, number of medications taken, and cortisolism, were recorded PRE and POST the observation period. Potential predictors of ∆BM in women (W) and men (M) with AD were calculated with a forward stepwise regression model. After one year of standard institutionalized diet, BM decreased significantly in AD (-2.5 kg; p < 0.01), while in CTRL remained unchanged (-0.4 kg; p = 0.8). AD patients and CTRL exhibited similar levels of daily energy expenditure (~1625 kcal/24h). The combination of three factors, number of medications taken, albuminemia, and cortisolism, predicted ∆BM in W with AD. At contrary, the best predictor of ∆BM in M with AD was the cortisolism. Despite a controlled energy intake and similar energy expenditure, both W and M with AD suffered of ∆BM. Therefore, controlled diet did not prevent this phenomenon. The assessments of these variables may predict W and M with AD at risk of weight loss

Electrical and mechanical response of finger flexor muscles during voluntary isometric contractions in elite rock-climbers.

To determine the differences between rock-climbers and controls in finger flexor (FF) motor units (MUs) features and activation strategy, eleven climbers and ten controls volunteered for the study. After maximal voluntary contraction (MVC) assessment, five levels of isometric contractions at 20, 40, 60, 80 and 100% MVC were performed. During contractions, electromyogram (EMG) and mechanomyogram (MMG) were recorded, from which the root mean square (RMS) and mean frequency (MF) were calculated. Climbers showed significantly higher MVC. EMG RMS was statistically higher in climbers than in controls from 60 to 100% MVC. In climbers MMG RMS increased up to 80% MVC, whereas in controls it increased only up to 60% MVC. MMG MF was higher in climbers than in controls from 60 to 100% MVC (P < 0.05). EMG-MMG combined analysis revealed significant differences in MU activation strategy between the two groups. The results are compatible with a shift of climbers' muscles toward faster MUs

Cardiac and autonomic adaptations to a wheelchair hockey match in athletes with muscular dystrophy

Muscular dystrophies (MD), such as Duchenne’s MD (DMD), appear in childhood and progressively lead to respiratory and/or heart failure. Exercise-based therapy may be helpful, but the cardiac and autonomic adaptations to sport activities are poorly studied in MD patients. Heart rate (HR) was measured in 30 players (all males, 28±6 [m±SD] years) with different forms of MD (divided into 2 groups according to pathology severity): (a) before, (b) during and (c) immediately after a wheelchair hockey match. In addition, HR variability (HRV) indexes RMSSD, SD1, LF, HF and LF/HF ratio were measured before and during the game in a subgroup of 9 DMD athletes. A sinus tachycardia was found in all MD athletes before the game (114±13 bpm in DMD, 113±18 bpm in other muscular dystrophies, OMD). In both DMD and OMD groups HR increased significantly from pre-game to game and decreased during recovery. During the game, HR was higher in the OMD compared to the DMD group. The subgroup of DMD athletes evidenced an almost normal parasympathetic withdrawal and altered sympathetic adaptations to exercise. Sinus tachycardia affects MD patients independently from MD form. However, the residual autonomic modulation allows the athletes to adapt to the energetic demands of wheelchair hockey