24 resultados para Cph (critical Point Hypothesis)
em BORIS: Bern Open Repository and Information System - Berna - Suiça
Resumo:
We explore a method developed in statistical physics which has been argued to have exponentially small finite-volume effects, in order to determine the critical temperature Tc of pure SU(3) gauge theory close to the continuum limit. The method allows us to estimate the critical coupling βc of the Wilson action for temporal extents up to Nτ∼20 with ≲0.1% uncertainties. Making use of the scale setting parameters r0 and t0−−√ in the same range of β-values, these results lead to the independent continuum extrapolations Tcr0=0.7457(45) and Tct0−−√=0.2489(14), with the latter originating from a more convincing fit. Inserting a conversion of r0 from literature (unfortunately with much larger errors) yields Tc/ΛMS¯¯¯¯¯=1.24(10).
Resumo:
Antegrade nailing of proximal humeral fractures using a straight nail can damage the bony insertion of the supraspinatus tendon and may lead to varus failure of the construct. In order to establish the ideal anatomical landmarks for insertion of the nail and their clinical relevance we analysed CT scans of bilateral proximal humeri in 200 patients (mean age 45.1 years (sd 19.6; 18 to 97) without humeral fractures. The entry point of the nail was defined by the point of intersection of the anteroposterior and lateral vertical axes with the cortex of the humeral head. The critical point was defined as the intersection of the sagittal axis with the medial limit of the insertion of the supraspinatus tendon on the greater tuberosity. The region of interest, i.e. the biggest entry hole that would not encroach on the insertion of the supraspinatus tendon, was calculated setting a 3 mm minimal distance from the critical point. This identified that 38.5% of the humeral heads were categorised as 'critical types', due to morphology in which the predicted offset of the entry point would encroach on the insertion of the supraspinatus tendon that may damage the tendon and reduce the stability of fixation. We therefore emphasise the need for 'fastidious' pre-operative planning to minimise this risk.
Resumo:
The paralysis-by-analysis phenomenon, i.e., attending to the execution of one's movement impairs performance, has gathered a lot of attention over recent years (see Wulf, 2007, for a review). Explanations of this phenomenon, e.g., the hypotheses of constrained action (Wulf et al., 2001) or of step-by-step execution (Masters, 1992; Beilock et al., 2002), however, do not refer to the level of underlying mechanisms on the level of sensorimotor control. For this purpose, a “nodal-point hypothesis” is presented here with the core assumption that skilled motor behavior is internally based on sensorimotor chains of nodal points, that attending to intermediate nodal points leads to a muscular re-freezing of the motor system at exactly and exclusively these points in time, and that this re-freezing is accompanied by the disruption of compensatory processes, resulting in an overall decrease of motor performance. Two experiments, on lever sequencing and basketball free throws, respectively, are reported that successfully tested these time-referenced predictions, i.e., showing that muscular activity is selectively increased and compensatory variability selectively decreased at movement-related nodal points if these points are in the focus of attention.
Resumo:
he physics program of the NA61/SHINE (SHINE = SPS Heavy Ion and Neutrino Experiment) experiment at the CERN SPS consists of three subjects. In the first stage of data taking (2007-2009) measurements of hadron production in hadron-nucleus interactions needed for neutrino (T2K) and cosmic-ray (Pierre Auger and KASCADE) experiments will be performed. In the second stage (2009-2010) hadron production in proton-proton and proton-nucleus interactions needed as reference data for a better understanding of nucleus-nucleus reactions will be studied. In the third stage (2009-2013) energy dependence of hadron production properties will be measured in p+p, p+Pb interactions and nucleus-nucleus collisions, with the aim to identify the properties of the onset of deconfinement and find evidence for the critical point of strongly interacting matter. The NA61 experiment was approved at CERN in June 2007. The first pilot run was performed during October 2007. Calibrations of all detector components have been performed successfully and preliminary uncorrected spectra have been obtained. High quality of track reconstruction and particle identification similar to NA49 has been achieved. The data and new detailed simulations confirm that the NA61 detector acceptance and particle identification capabilities cover the phase space required by the T2K experiment. This document reports on the progress made in the calibration and analysis of the 2007 data.
Resumo:
We investigate the SU(3)-invariant sector of the one-parameter family of SO(8) gauged maximal supergravities that has been recently discovered. To this end, we construct the N=2 truncation of this theory and analyse its full vacuum structure. The number of critical point is doubled and includes new N=0 and N=1 branches. We numerically exhibit the parameter dependence of the location and cosmological constant of all extrema. Moreover, we provide their analytic expressions for cases of special interest. Finally, while the mass spectra are found to be parameter independent in most cases, we show that the novel non-supersymmetric branch with SU(3) invariance provides the first counterexample to this.
Resumo:
Pulmonary airways are subdivided into conducting and gas-exchanging airways. An acinus is defined as the small tree of gas-exchanging airways, which is fed by the most distal purely conducting airway. Until now a dissector of five consecutive sections or airway casts were used to count acini. We developed a faster method to estimate the number of acini in young adult rats. Right middle lung lobes were critical point dried or paraffin embedded after heavy metal staining and imaged by X-ray micro-CT or synchrotron radiation-based X-rays tomographic microscopy. The entrances of the acini were counted in three-dimensional (3D) stacks of images by scrolling through them and using morphological criteria (airway wall thickness and appearance of alveoli). Segmentation stopper were placed at the acinar entrances for 3D visualizations of the conducting airways. We observed that acinar airways start at various generations and that one transitional bronchiole may serve more than one acinus. A mean of 5612 (±547) acini per lung and a mean airspace volume of 0.907 (±0.108) μL per acinus were estimated. In 60-day-old rats neither the number of acini nor the mean acinar volume did correlate with the body weight or the lung volume.
Resumo:
A quantum critical point (QCP) is a singularity in the phase diagram arising because of quantum mechanical fluctuations. The exotic properties of some of the most enigmatic physical systems, including unconventional metals and superconductors, quantum magnets and ultracold atomic condensates, have been related to the importance of critical quantum and thermal fluctuations near such a point. However, direct and continuous control of these fluctuations has been difficult to realize, and complete thermodynamic and spectroscopic information is required to disentangle the effects of quantum and classical physics around a QCP. Here we achieve this control in a high-pressure, high-resolution neutron scattering experiment on the quantum dimer material TlCuCl3. By measuring the magnetic excitation spectrum across the entire quantum critical phase diagram, we illustrate the similarities between quantum and thermal melting of magnetic order. We prove the critical nature of the unconventional longitudinal (Higgs) mode of the ordered phase by damping it thermally. We demonstrate the development of two types of criticality, quantum and classical, and use their static and dynamic scaling properties to conclude that quantum and thermal fluctuations can behave largely independently near a QCP.
Resumo:
We provide the dictionary between four-dimensional gauged supergravity and type II compactifications on T6 with metric and gauge fluxes in the absence of supersymmetry breaking sources, such as branes and orientifold planes. Secondly, we prove that there is a unique isotropic compactification allowing for critical points. It corresponds to a type IIA background given by a product of two 3-tori with SO(3) twists and results in a unique theory (gauging) with a non-semisimple gauge algebra. Besides the known four AdS solutions surviving the orientifold projection to N = 4 induced by O6-planes, this theory contains a novel AdS solution that requires non-trivial orientifold-odd fluxes, hence being a genuine critical point of the N = 8 theory.
Resumo:
We derive the fermion loop formulation for the supersymmetric nonlinear O(N) sigma model by performing a hopping expansion using Wilson fermions. In this formulation the fermionic contribution to the partition function becomes a sum over all possible closed non-oriented fermion loop configurations. The interaction between the bosonic and fermionic degrees of freedom is encoded in the constraints arising from the supersymmetry and induces flavour changing fermion loops. For N ≥ 3 this leads to fermion loops which are no longer self-avoiding and hence to a potential sign problem. Since we use Wilson fermions the bare mass needs to be tuned to the chiral point. For N = 2 we determine the critical point and present boson and fermion masses in the critical regime.
Resumo:
We present experimental results on inclusive spectra and mean multiplicities of negatively charged pions produced in inelastic p+p interactions at incident projectile momenta of 20, 31, 40, 80 and 158GeV/c (√s = 6.3, 7.7,8.8, 12.3 and 17.3GeV, respectively). The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN super proton synchrotron. Two-dimensional spectra are determined in terms of rapidity and transverse momentum. Their properties such as the width of rapidity distributions and the inverse slope parameter of transverse mass spectra are extracted and their collision energy dependences are presented. The results on inelastic p+p interactions are compared with the corresponding data on central Pb+Pb collisions measured by the NA49 experiment at the CERNSPS. The results presented in this paper are part of the NA61/SHINE ion program devoted to the study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter. They are required for interpretation of results on nucleus–nucleus and proton–nucleus collisions.
Resumo:
This paper presents a first exploration of the syntactic abilities of autistic children using the framework of truncation theory (Rizzi 1993-4, 2000). It is the first step of an ongoing research project aiming to (a) provide a complete map of syntax in autism, for such work has never been attempted from a sound linguistic perspective (b) develop a targeted remediation program to enhance syntactic abilities of autistic children. Recently, a growing body of work has emphasized the existence of a causal relation between the acquisition of complex syntax (embedding) and the development of a theory of mind (in normally-developing, deaf and autistic children). Early identification and remediation of syntactic deficits is therefore crucial not only to enhance cognitive abilites related to theory of mind, but also because of the critical period hypothesis for language acquisition.
Resumo:
Despite successful intensive care a substantial portion of critically ill patients dies after discharge from the intensive care unit or hospital. Observational studies investigating long-term survival of critically ill patients reported that most deaths occur during the first months or year after discharge. Only limited data on the causes of impaired quality of life and post-intensive care unit deaths exist in the current literature. In this manuscript we hypothesize that the acute inflammatory response which characteristically accompanies critical illness is ensued by a prolonged imbalance or activation of the immune system. Such a chronic low-grade inflammatory response to critical illness may be sub-clinical and persist for a variable period of time after discharge from the intensive care unit and hospital. Chronic inflammation is a well-recognized risk factor for long-term morbidity and mortality, particularly from cardiovascular causes, and may thus partly contribute to the impaired quality of life as well as increased morbidity and mortality following intensive care unit and hospital discharge of critically ill patients. Assuming that critical illness is indeed followed by a prolonged inflammatory response, important implications for treatment would arise. An interesting and potentially beneficial therapy could be the administration of immune-modulating drugs during the time after intensive care unit or hospital discharge until chronic inflammation has subsided. Statins are well-investigated and effective drugs to attenuate chronic inflammation and could potentially also improve long-term outcome of critically ill patients after intensive care unit or hospital discharge. Future studies evaluating the course of inflammation during and after critical illness as well as its response to statin therapy are required.
Resumo:
To test the hypothesis that muscle fibers are depolarized in patients with critical illness myopathy by measuring velocity recovery cycles (VRCs) of muscle action potentials.
Resumo:
Patients with critical limb ischaemia have a high rate of amputation and mortality. We tested the hypothesis that non-viral 1 fibroblast growth factor (NV1FGF) would improve amputation-free survival.
Resumo:
Recommendations stated in the TASC II guidelines for the treatment of peripheral arterial disease (PAD) regard a heterogeneous group of patients ranging from claudicants to critical limb ischaemia (CLI) patients. However, specific considerations apply to CLI patients. An important problem regarding the majority of currently available literature that reports on revascularisation strategies for PAD is that it does not focus on CLI patients specifically and studies them as a minor part of the complete cohort. Besides the lack of data on CLI patients, studies use a variety of endpoints, and even similar endpoints are often differentially defined. These considerations result in the fact that most recommendations in this guideline are not of the highest recommendation grade. In the present chapter the treatment of CLI is not based on the TASC II classification of atherosclerotic lesions, since definitions of atherosclerotic lesions are changing along the fast development of endovascular techniques, and inter-individual differences in interpretation of the TASC classification are problematic. Therefore we propose a classification merely based on vascular area of the atherosclerotic disease and the lesion length, which is less complex and eases the interpretation. Lesions and their treatment are discussed from the aorta downwards to the infrapopliteal region. For a subset of lesions, surgical revascularisation is still the gold standard, such as in extensive aorto-iliac lesions, lesions of the common femoral artery and long lesions of the superficial femoral artery (>15 cm), especially when an applicable venous conduit is present, because of higher patency and limb salvage rates, even though the risk of complications is sometimes higher than for endovascular strategies. It is however more and more accepted that an endovascular first strategy is adapted in most iliac, superficial femoral, and in some infrapopliteal lesions. The newer endovascular techniques, i.e. drug-eluting stents and balloons, show promising results especially in infrapopliteal lesions. However, most of these results should still be confirmed in large RCTs focusing on CLI patients. At some point when there is no possibility of an endovascular nor a surgical procedure, some alternative non-reconstructive options have been proposed such as lumbar sympathectomy and spinal cord stimulation. But their effectiveness is limited especially when assessing the results on objective criteria. The additional value of cell-based therapies has still to be proven from large RCTs and should therefore still be confined to a research setting. Altogether this chapter summarises the best available evidence for the treatment of CLI, which is, from multiple perspectives, completely different from claudication. The latter also stresses the importance of well-designed RCTs focusing on CLI patients reporting standardised endpoints, both clinical as well as procedural.