Stable and unstable perturbations in universal scaling phenomena far from equilibrium

We study the dynamics of perturbations around nonthermal fixed points associated to universal scaling phenomena in quantum many-body systems far from equilibrium. For an N-component scalar quantum field theory in 3+1 space-time dimensions, we determine the stability scaling exponents using a self-consistent large-N expansion to next-to-leading order. Our analysis reveals the presence of both stable and unstable perturbations, the latter leading to quasi-exponential deviations from the fixed point in the infrared. We identify a tower of far-from-equilibrium quasi-particle states and their dispersion relations by computing the spectral function. With the help of linear response theory, we demonstrate that unstable dynamics arises from a competition between elastic scattering processes among the quasi-particle states. What ultimately renders the fixed point dynamically attractive is the phenomenon of a scaling instability, which is the universal scaling of the unstable regime towards the infrared due to a self-similar quasi-particle cascade. Our results provide ab initio understanding of emergent stability properties in self-organized scaling phenomena.Comment: 6 pages, 5 figures, PRL version (minor text changes

APPLICATION OF AN ARMA-MODEL AS A METHOD OF TIME-VARIANT SPECTRAL ANALYSIS TO SURFACE EMG-SIGNALS IN SWIM BENCH EXERCISES

The purpose of this study is the determination of spectral parameters of surface EMG signals during a swim specific exercise by means of an ARMA model. This method is suitable for nonstationary signals such as EMG, MEG and EMG. Nine female top elite swimmers participated in this research. During a two minute swim bench exercise the momentary median frequency decreases. Changes of the EMG power for the diHerent wave bands could be found. By means of this analysis information aboul fatigue and changes in the intramuscular coordination are possible

EVALUATION OF A SWIM BENCH

Swim benches are used in dry-land training and for performance diagnosis by most elite swimmers. For the purpose of diagnosis generally the swimmer's mechanical output power is measured. But there are some problems: E. g. the influence of the water resistance and the influence of the legs' power to swimming are not included in a swim bench test. Competitive performances (200 m) and data from swim bench tests (average mechanical output power) of four elite female swimmers (one participant of Olympic finals 2000 and three participants of German championships) over a period of two years were correlated for each swimmer. The results suggest, that swim benches are useful for an individual performance diagnosis if the mechanical output power is acquired

Thermalization in QCD: theoretical approaches, phenomenological applications, and interdisciplinary connections

Heavy-ion collisions at BNL's Relativistic Heavy-Ion Collider (RHIC) and CERN's Large Hadron Collider (LHC) provide strong evidence for the formation of a quark-gluon plasma, with temperatures extracted from relativistic viscous hydrodynamic simulations shown to be well above the transition temperature from hadron matter. How the strongly correlated quark-gluon matter forms in a heavy-ion collision, its properties off-equilibrium, and the thermalization process in the plasma, are outstanding problems in QCD. We review here the theoretical progress in this field in weak coupling QCD effective field theories and in strong coupling holographic approaches based on gauge-gravity duality. We outline the interdisciplinary connections of different stages of the thermalization process to non-equilibrium dynamics in other systems across energy scales ranging from inflationary cosmology, to strong field QED, to ultracold atomic gases, with emphasis on the universal dynamics of non-thermal and of hydrodynamic attractors. We survey measurements in heavy-ion collisions that are sensitive to the early non-equilibrium stages of the collision and discuss the potential for future measurements. We summarize the current state-of-the art in thermalization studies and identify promising avenues for further progress.Comment: 79 pages, 34 figures, prepared for Reviews of Modern Physics; version 2: small improvements and additions, submitted versio

Time-variant spectral analysis of surface EMG – Applications in sports practice

The aim of this paper is the presentation of time-variant spectrograms of surface EMG signals to estimate fatigue processes in muscle and to consider recruitments of motor units. For this we used techniques on the base of ARMA and AR models. We illustrate our applications by three examples: influence of training to maximal and explosive isometric contraction, fatigue processes in an all-out cycling exercise and intramuscular coordination during a fast movement

EMMI Rapid Reaction Task Force on "Thermalization in Non-abelian Plasmas"

Recently, different proposals have been put forward on how thermalization proceeds in heavy-ion collisions in the idealized limit of very large nuclei at sufficiently high energy. Important aspects of the parametric estimates at weak coupling may be tested using well-established classical-statistical lattice simulations of the far-from-equilibrium gluon dynamics. This has to be confronted with strong coupling scenarios in related theories based on gauge-string dualities. Furthermore, closely related questions about far-from-equilibrium dynamics arise in early-universe cosmology and in non-relativistic systems of ultracold atoms. These were central topics of the EMMI Rapid Reaction Task Force meeting held on December 12-14, 2011, at the University of Heidelberg, which we report on.Comment: 13 pages, summary of the EMMI Rapid Reaction Task Force on "Thermalization in Non-abelian Plasmas", December 12-14, 2011, University of Heidelberg, German

Prevalence and Infant Mortality of Major Congenital Malformations Stratified by Birthweight

Background: Low birthweight and major congenital malformations (MCMs) are key causes of infant mortality. Objectives: The aim of this study was to explore the prevalence of MCMs in infants with low and very low birthweight and analyze the impact of MCMs and birthweight on infant mortality. Methods: We determined prevalence and infant mortality of 28 life-threatening MCMs in very-low-birthweight (75% (10,316) had severe congenital heart disease. The prevalence (per 10,000) of any/cardiac MCM was increased in VLBW (286/176) and LBW (244/143), as compared to NBW infants (38/32). Infant mortality rates were significantly higher in infants with an MCM, as opposed to infants without an MCM, in each birthweight group (VLBW 28.5% vs. 11.5%, LBW 16.7% vs. 0.9%, and NBW 8.6% vs. 0.1%). For most MCMs, observed survival rates in VLBW and LBW infants were lower than expected, as calculated from survival rates of VLBW or LBW infants without an MCM, and NBW infants with an MCM. Conclusions: Infants with an MCM are more often born with LBW or VLBW, as opposed to infants without an MCM. Many MCMs carry significant excess mortality when occurring in VLBW or LBW infants

The course of pain intensity in patients undergoing herniated disc surgery: a 5-year longitudinal observational study

Objectives: The aims of this study are to answer the following questions (1) How does the pain intensity of lumbar and cervical disc surgery patients change within a postoperative time frame of 5 years? (2) Which sociodemographic, medical, work-related, and psychological factors are associated with postoperative pain in lumbar and cervical disc surgery patients? Methods: The baseline survey (T0; n = 534) was conducted 3.6 days (SD 2.48) post-surgery in the form of face-to-face interviews. The follow-up interviews were conducted 3 months (T1; n = 486 patients), 9 months (T2; n = 457), 15 months (T3; n = 438), and 5 years (T4; n = 404) post-surgery. Pain intensity was measured on a numeric rating-scale (NRS 0–100). Estimated changes to and influences on postoperative pain by random effects were accounted by regression models. Results: Average pain decreased continuously over time in patients with lumbar herniated disc (Wald Chi² = 25.97, p<0.001). In patients with cervical herniated disc a reduction of pain was observed, albeit not significant (Chi² = 7.02, p = 0.135). Two predictors were associated with postoperative pain in lumbar and cervical disc surgery patients: the subjective prognosis of gainful employment (p<0.001) and depression (p<0.001). Conclusion: In the majority of disc surgery patients, a long-term reduction of pain was observed. Cervical surgery patients seemed to benefit less from surgery than the lumbar surgery patients. A negative subjective prognosis of gainful employment and stronger depressive symptoms were associated with postoperative pain. The findings may promote multimodal rehabilitation concepts including psychological and work-related support

A multiscale study of hot-extruded CoNiGa ferromagnetic shape-memory alloys

Ferromagnetic shape-memory CoNiGa alloys have attracted much scientific interest due to their potential alternative use as high-temperature shape-memory alloys, bearing a high prospect for actuation and damping applications at elevated temperatures. Yet, polycrystalline CoNiGa, due to strong orientation dependence of transformation strains, suffers from intergranular fracture. Here, two multi-grain CoNiGa samples were prepared by a novel hot extrusion process that can promote favourable grain-boundary orientation distribution and improve the material's mechanical behaviour. The samples were investigated by multiple methods and their microstructural, magnetic, and mechanical properties are reported. It is found that a post-extrusion solutionising heat treatment leads to the formation of a two-phase oligocrystalline homogeneous microstructure consisting of an austenitic parent B2 phase and γ-CoNiGa precipitates. Reconstruction of the full 3D grain morphology revealed large, nearly spherical grains with no low-angle grain boundaries throughout the entire sample volume. The presence of γ precipitation affects the transformation behaviour of the samples, by lowering the martensitic transformation temperature, while, in conjunction with the oligocrystalline microstructure, it improves the ductility. Controlling the composition of the B2 matrix, as well as the phase fraction of the γ phase, is thus crucial for the optimal behaviour of the alloys