Statistical Mechanics of systems with long range interactions

Recent theoretical studies of statistical mechanical properties of systems with long range interactions are briefly reviewed. In these systems the interaction potential decays with a rate slower than 1/r^d at large distances r in d dimensions. As a result, these systems are non-additive and they display unusual thermodynamic and dynamical properties which are not present in systems with short range interactions. In particular, the various statistical mechanical ensembles are not equivalent and the microcanonical specific heat may be negative. Long range interactions may also result in breaking of ergodicity, making the maximal entropy state inaccessible from some regions of phase space. In addition, in many cases long range interactions result in slow relaxation processes, with time scales which diverge in the thermodynamic limit. Various models which have been found to exhibit these features are discussed.Comment: Published in AIP Conference Proceedings 970 "Dynamics and Thermodynamics of Systems with Long-Range Interactions: Theory and Experiments", Assisi, Italy 4-8 July 2007, editors A. Campa, A. Giansanti, G. Morigi and F. Sylos Labini, p. 22 (2008

Equilibrium and out of equilibrium phase transitions in systems with long range interactions and in 2D flows

In self-gravitating stars, two dimensional or geophysical flows and in plasmas, long range interactions imply a lack of additivity for the energy; as a consequence, the usual thermodynamic limit is not appropriate. However, by contrast with many claims, the equilibrium statistical mechanics of such systems is a well understood subject. In this proceeding, we explain briefly the classical approach to equilibrium and non equilibrium statistical mechanics for these systems, starting from first principles. We emphasize recent and new results, mainly a classification of equilibrium phase transitions, new unobserved equilibrium phase transition, and out of equilibrium phase transitions. We briefly discuss what we consider as challenges in this field

Association of regional bioelectrical phase angle with physical performance: a pilot study in elite rowers

Background. This study aimed to examine the association between regional Phase Angle (PhA) and physical performance in athletes where the use of specific body segments is required.Methods. Sixteen elite-level rowers (13 male aged 17.6 +/- 2.1 yr; 3 female aged 21.0 +/- 4.4 yr) participated in this investigation. Raw bioimpedance parameters were obtained with a phase-sensitive 50 kHz bioelectrical impedance analysis (BIA) device and fat-free mass, percentage of fat mass (FM%), and arms and legs lean soft tissue (ALST and LLST, respectively) were estimated using specific BIA-equation developed for athletes. The time (2000t) and the mean power (MP) expressed during the 2000 m test performed on a rowing ergometer were measured.Results. The major findings of the study were that upper hemisome PhA (UPhA) were more strongly related with 2000t (R2 = 0.35, p = 0.015) and MP (R2 = 0.40, p = 0.009) than whole-body PhA. Additionally, not only UPhA maintained a significant relationship with 2000t (p = 0.001) and MP (p = 0.001), even after adjustment for the co-variables sex, ALST, and FM%, but the explained variance increased to R2 = 0.72 and R2 = 0.78, respectively.Conclusions. These results suggest that the regional PhA might be used as a tool for evaluating performance related parameters in sports where specific body segments are involved, preferring it to the whole-body measured value

Maturity Related Differences in Body Composition Assessed by Classic and Specific Bioimpedance Vector Analysis among Male Elite Youth Soccer Players

The aim of this study was to analyze the efficiency of classic and specific bioelectrical impedance vector analysis (BIVA) in the assessment of maturity related differences in body composition among male elite youth soccer players, and to provide bioelectrical impedance reference data for this category. A group of 178 players (aged 12.1 ± 1.6 years) were registered in a professional Italian soccer team participating in the first division (Serie A). They were divided into three groups according to their maturity status while bioelectrical resistance and reactance were obtained. The classic and specific BIVA procedures were applied, which correct bioelectrical values for body height and body geometry, respectively. Percentage of fat mass (FM%) and total body water (TBW (L)) were estimated from bioelectrical values. Age-specific z-scores of the predicted age at peak height velocity identified 29 players as earlier-, 126 as on time-, and 23 as later-maturing. TBW was higher (p < 0.01) in adolescents classified as “early” maturity status compared to the other two groups and classic BIVA confirmed these results. Conversely, no differences in FM% were found among the groups. Specific vector length showed a higher correlation (r = 0.748) with FM% compared with the classic approach (r = 0.493). Classic vector length showed a stronger association (r = −0.955) with TBW compared with specific (r = −0.263). Specific BIVA turns out to be accurate for the analysis of FM% in athletes, while classic BIVA shows to be a valid approach to evaluate TBW. An original data set of bioelectric impedance reference values of male elite youth soccer players was provide

Vesical Imaging-Reporting and Data System (VI-RADS) incorporated into bladder cancer clinical practice: what’s the perspectives beyond diagnostic accuracy?

No abstract availabl

Inflammatory Mediators and Angiogenic Factors in Choroidal Neovascularization: Pathogenetic Interactions and Therapeutic Implications

Choroidal neovascularization (CNV) is a common and severe complication in heterogeneous diseases affecting the posterior segment of the eye, the most frequent being represented by age-related macular degeneration. Although the term may suggest just a vascular pathological condition, CNV is more properly definable as an aberrant tissue invasion of endothelial and inflammatory cells, in which both angiogenesis and inflammation are involved. Experimental and clinical evidences show that vascular endothelial growth factor is a key signal in promoting angiogenesis. However, many other molecules, distinctive of the inflammatory response, act as neovascular activators in CNV. These include fibroblast growth factor, transforming growth factor, tumor necrosis factor, interleukins, and complement. This paper reviews the role of inflammatory mediators and angiogenic factors in the development of CNV, proposing pathogenetic assumptions of mutual interaction. As an extension of this concept, new therapeutic approaches geared to have an effect on both the vascular and the extravascular components of CNV are discussed

The eccentric phase in unilateral resistance training enhances and preserves the contralateral knee extensors strength gains after detraining in women: a randomized controlled trial

The current randomized controlled study investigated whether or not the inclusion of the eccentric phase in resistance training favors the contralateral strength gains after different unilateral protocols, and whether such gains are retained after detraining. Sixty healthy women were randomly assigned to a unilateral concentric-only (CONC), eccentric-only (ECC), concentric-eccentric (TRAD) volume-equated knee extension training or control group (CON). The participants trained 2 days/week for 8 weeks and then did not train for further 8 weeks. Knee extensors isokinetic concentric, eccentric, and isometric peak torque and vastus lateralis muscle thickness were assessed in the contralateral limb at baseline, post-training, and post-detraining. At post-training, concentric peak torque increased in CONC [+9.2%, 95%CI (+6.2/+12.3), p < 0.001, ES: 0.70, 95%CI (0.01/1.39)], ECC [+11.0% (+7.7/+14.2), p < 0.001: ES: 0.66(0.09/1.23)] and TRAD [+8.5%(+5.7/+11.6), p < 0.001, ES: 0.50(0.02/0.98)]. Eccentric peak torque increased in ECC in ECC [+15.0%(+11.4/+20.7), p < 0.001, ES: 0.91(0.14/1.63)] and TRAD [+5.5%(+0.3/10.7), p = 0.013, ES: 0.50(0.05/0.95)]. Isometric peak torque increased in ECC [+11.3(+5.8/16.8), p < 0.001, ES: 0.52(0.10/0.94)] and TRAD [+8.6%(+3.4/+13.7), p < 0.001, ES: 0.55(0.14/0.96)]. No change in eccentric and isometric peak torque occurred in CONC (p > 0.05). Muscle thickness did not change in any group (p > 0.05). At post-detraining, all groups preserved the contralateral strength gains observed at post-training (p < 0.05). The findings showed that ECC and TRAD increased contralateral knee extensors strength in concentric, eccentric, and isometric modality, while CONC only increased concentric strength. The eccentric phase appears to amplify the cross-education effect, permitting a transfer in strength gaining toward multiple testing modalities. Both eccentric-based and traditional eccentric-concentric resistance protocols are recommended to increase the contralateral retention in strength gains after a detraining period

Markers of neurodevelopmental impairments in early-onset psychosis

Background: The aim of this study was to assess the association between the clinical and neurobiological markers of neurodevelopmental impairments and early-onset schizophrenia spectrum psychosis. Methods: A sample of 36 patients with early-onset schizophrenia spectrum psychosis was compared to a control sample of 36 patients with migraine. We assessed early childhood neurodevelopmental milestones using a modified version of the General Developmental Scale, general intellectual ability using the Wechsler Intelligence Scale for Children–Revised or Leiter International Performance Scale–Revised for patients with speech and language abnormalities, and neurological soft signs with specific regard to subtle motor impairment. Results: Subjects with early-onset psychosis had a higher rate of impaired social development (P=0.001), learning difficulties (P=0.04), enuresis (P=0.0008), a lower intelligence quotient (P,0.001), and subtle motor impairments (P=0.005) than control subjects. Conclusion: We suggest that neurodevelopment in early-onset psychosis is characterized by a global impairment of functional and adaptive skills that manifests from early childhood, rather than a delay or limitation in language and motor development. The current evidence is based on a small sample and should be investigated in larger samples in future research. Keywords: early-onset psychosis, early-onset schizophrenia, neurodevelopment, social cognition, intellectual disabilitie