22 resultados para Critical exponents and amplitudes (theory)

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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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).

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The prevention of ischaemia and the adequate restitution of blood flow to ischaemic tissue are pivotal to halt the progression of cellular injury associated with decreased oxygen and nutrient supply. Accordingly, the search for novel strategies which aim at preventing ischaemia-reperfusion-induced tissue damage is still of major interest in flap surgery. Preconditioning represents an elegant approach to render the tissue more resistant against deleterious ischaemic insults. For many decades, 'surgical delay' has been the standard method of tissue preconditioning. During the last 10 years, ischaemic preconditioning was added to the repertoire of plastic surgeons to protect flaps from ischaemic necrosis. The invasiveness and expenditure of time of these procedures, however, have always been major drawbacks, hindering a wide distribution in clinical practice. Consequently, the motivation has all along been to further refine and simplify protective strategies. Recent experimental studies have now shown that efficient protection from ischaemic necrosis can also be achieved by remote preconditioning or pretreatment with chemical agents and growth factors, which mimic the action of surgical delay and ischaemic preconditioning. In addition, the local application of unspecific stressors, including both heating and cooling, have been shown to effectively improve flap microcirculation and, thus, tissue survival. In view of successful translational research, it is now time that the efficacy of these novel preconditioning procedures is proven in prospective randomised clinical trials.

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Purpose – There is much scientific interest in the connection between the emergence of gender-based inequalities and key biographical transition points of couples in long-term relationships. Little empirical research is available comparing the evolution of a couple’s respective professional careers over space and time. The purpose of this paper is to contribute to filling this gap by addressing the following questions: what are the critical biographical moments when gender (in)equalities within a relationship begin to arise and consolidate? Which biographical decisions precede and follow such critical moments? How does decision making at critical moments impact the opportunities of both relationship partners in gaining equal access to paid employment? Design/methodology/approach – These questions are addressed from the perspectives of intersectionality and economic citizenship. Biographical interviewing is used to collect the personal and professional narratives of Swiss-, bi-national and migrant couples. The case study of a Swiss-Norwegian couple illustrates typical processes by which many skilled migrant women end up absently or precariously employed. Findings – Analysis reveals that the Scandinavian woman’s migration to Switzerland is a primary and critical moment for emerging inequality, which is then reinforced by relocation (to a small town characterized by conservative gender values) and the subsequent births of their children. It is concluded that factors of traditional gender roles, ethnicity and age intersect to create a hierarchical situation which affords the male Swiss partner more weight in terms of decision making and career advancement. Practical implications – The paper’s findings are highly relevant to the formulation of policies regarding gender inequalities and the implementation of preventive programmes within this context. Originality/value – Little empirical research is available comparing the evolution of a couple’s respective professional careers over space and time. The originality of this paper is to fill this research gap; to include migration as a critical moment for gender inequalities; to use an intersectional and geographical perspective that have been given scant attention in the literature; to use the original concept of economic citizenship; and to examine the case of a bi-national couple, which has so far not been examined by the literature on couple relationships.

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Background: Cognitive–behavioural therapy is efficacious in the treatment of major depressive disorder but response rates are still far from satisfactory. Aims: To better understand brain responses to individualised emotional stimuli and their association with outcome, to enhance treatment. Method: Functional magnetic resonance imaging data were collected prior to individual psychotherapy. Differences in brain activity during passive viewing of individualised self-critical material in 23 unmedicated out-patients with depression and 28 healthy controls were assessed. The associations between brain activity, cognitive and emotional change, and outcome were analysed in 21 patients. Results: Patients showed enhanced activity in the amygdala and ventral striatum compared with the control group. Non-response to therapy was associated with enhanced activity in the right amygdala compared with those who responded, and activity in this region was negatively associated with outcome. Emotional but not cognitive changes mediated this association. Conclusions: Amygdala hyperactivity may lessen symptom improvement in psychotherapy for depression through attenuating emotional skill acquisition.

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Numerical calculations describing weathering of the Poços de Caldas alkaline complex (Minas Gerais, Brazil) by infiltrating groundwater are carried out for time spans up to two million years in the absence of pyrite, and up to 500,000 years with pyrite present. Deposition of uranium resulting from infiltration of oxygenated, uranium bearing groundwater through the hydrothermally altered phonolitic host rock at the Osamu Utsumi uranium mine is also included in the latter calculation. The calculations are based on the quasi-stationary state approximation to mass conservation equations for pure advective transport. This approximation enables the prediction of solute concentrations, mineral abundances and porosity as functions of time and distance over geologic time spans. Mineral reactions are described by kinetic rate laws for both precipitation and dissolution. Homogeneous equilibrium is assumed to be maintained within the aqueous phase. No other constraints are imposed on the calculations other than the initial composition of the unaltered host rock and the composition of the inlet fluid, taken as rainwater modified by percolation through a soil zone. The results are in qualitative agreement with field observations at the Osamu Utsumi uranium mine. They predict a lateritic cover followed by a highly porous saprolitic zone, a zone of oxidized rock with pyrite replaced by iron-hydroxide, a sharp redox front at which uranium is deposited, and the reduced unweathered host rock. Uranium is deposited in a narrow zone located on the reduced side of the redox front in association with pyrite, in agreement with field observations. The calculations predict the formation of a broad dissolution front of primary kaolinite that penetrates deep into the host rock accompanied by the precipitation of secondary illite. Secondary kaolinite occurs in a saprolitic zone near the surface and in the vicinity of the redox front. Gibbsite forms a bi-modal distribution consisting of a maximum near the surface followed by a thin tongue extending downward into the weathered profile in agreement with field observations. The results are found to be insensitive to the kinetic rate constants used to describe mineral reactions.

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Conventional wisdom on the insufficiency of existing WTO disciplines on export restrictions has triggered momentum on the issue. In this book, Ilaria Espa offers a comprehensive analysis of the scope and coverage of WTO disciplines on export restrictions in light of emerging case law. She investigates whether such rules still provide a credible and effective framework capable of preventing abuses in the use of export restrictive measures on critical minerals and metals during a period of economic crisis and change in international trade patterns. Giving a broad overview of the export restrictions applied to these materials, Espa identifies distinctive features in the proliferation of export barriers and analyses the existing WTO rules to reveal their gaps and inconsistencies. She goes on to present solutions based upon her findings with the aim of bringing more coherence and equity to WTO rules on the export side.