The renormalization group inspired approaches and estimates of the tenth-order corrections to the muon anomaly in QED

We present the estimates of the five-loop QED corrections to the muon anomaly using the scheme-invariant approaches and demonstrate that they are in good agreement with the results of exact calculations of the corresponding tenth-order diagrams supplemented by the additional guess about the values of the non-calculated contributions.Comment: LATEX 15 pages, figures available upon request; preprint CERN-TH.7518/9

Solving loop equations by Hitchin systems via holography in large-N QCD_4

For (planar) closed self-avoiding loops we construct a "holographic" map from the loop equations of large-N QCD_4 to an effective action defined over infinite rank Hitchin bundles. The effective action is constructed densely embedding Hitchin systems into the functional integral of a partially quenched or twisted Eguchi-Kawai model, by means of the resolution of identity into the gauge orbits of the microcanonical ensemble and by changing variables from the moduli fields of Hitchin systems to the moduli of the corresponding holomorphic de Rham local systems. The key point is that the contour integral that occurs in the loop equations for the de Rham local systems can be reduced to the computation of a residue in a certain regularization. The outcome is that, for self-avoiding loops, the original loop equations are implied by the critical equation of an effective action computed in terms of the localisation determinant and of the Jacobian of the change of variables to the de Rham local systems. We check, at lowest order in powers of the moduli fields, that the localisation determinant reproduces exactly the first coefficient of the beta function.Comment: 65 pages, late

25 Years of Self-organized Criticality: Concepts and Controversies

Introduced by the late Per Bak and his colleagues, self-organized criticality (SOC) has been one of the most stimulating concepts to come out of statistical mechanics and condensed matter theory in the last few decades, and has played a significant role in the development of complexity science. SOC, and more generally fractals and power laws, have attracted much comment, ranging from the very positive to the polemical. The other papers (Aschwanden et al. in Space Sci. Rev., 2014, this issue; McAteer et al. in Space Sci. Rev., 2015, this issue; Sharma et al. in Space Sci. Rev. 2015, in preparation) in this special issue showcase the considerable body of observations in solar, magnetospheric and fusion plasma inspired by the SOC idea, and expose the fertile role the new paradigm has played in approaches to modeling and understanding multiscale plasma instabilities. This very broad impact, and the necessary process of adapting a scientific hypothesis to the conditions of a given physical system, has meant that SOC as studied in these fields has sometimes differed significantly from the definition originally given by its creators. In Bak’s own field of theoretical physics there are significant observational and theoretical open questions, even 25 years on (Pruessner 2012). One aim of the present review is to address the dichotomy between the great reception SOC has received in some areas, and its shortcomings, as they became manifest in the controversies it triggered. Our article tries to clear up what we think are misunderstandings of SOC in fields more remote from its origins in statistical mechanics, condensed matter and dynamical systems by revisiting Bak, Tang and Wiesenfeld’s original papers

Development of a core descriptor set for Crohn's anal fistula

AIM: Crohn's anal fistula (CAF) is a complex condition, with no agreement on which patient characteristics should be routinely reported in studies. The aim of this study was to develop a core descriptor set of key patient characteristics for reporting in all CAF research. METHOD: Candidate descriptors were generated from published literature and stakeholder suggestions. Colorectal surgeons, gastroenterologists and specialist nurses in inflammatory bowel disease took part in three rounds of an international modified Delphi process using nine-point Likert scales to rank the importance of descriptors. Feedback was provided between rounds to allow refinement of the next ratings. Patterns in descriptor voting were assessed using principal component analysis (PCA). Resulting PCA groups were used to organize items in rounds two and three. Consensus descriptors were submitted to a patient panel for feedback. Items meeting predetermined thresholds were included in the final set and ratified at the consensus meeting. RESULTS: One hundred and thirty three respondents from 22 countries completed round one, of whom 67.0% completed round three. Ninety seven descriptors were rated across three rounds in 11 PCA-based groups. Forty descriptors were shortlisted. The consensus meeting ratified a core descriptor set of 37 descriptors within six domains: fistula anatomy, current disease activity and phenotype, risk factors, medical interventions for CAF, surgical interventions for CAF, and patient symptoms and impact on quality of life. CONCLUSION: The core descriptor set proposed for all future CAF research reflects characteristics important to gastroenterologists and surgeons. This might aid transparent reporting in future studies

Prognostic indicators and outcomes of hospitalised COVID-19 patients with neurological disease: An individual patient data meta-analysis

Background Neurological COVID-19 disease has been reported widely, but published studies often lack information on neurological outcomes and prognostic risk factors. We aimed to describe the spectrum of neurological disease in hospitalised COVID-19 patients; characterise clinical outcomes; and investigate factors associated with a poor outcome. Methods We conducted an individual patient data (IPD) meta-analysis of hospitalised patients with neurological COVID-19 disease, using standard case definitions. We invited authors of studies from the first pandemic wave, plus clinicians in the Global COVID-Neuro Network with unpublished data, to contribute. We analysed features associated with poor outcome (moderate to severe disability or death, 3 to 6 on the modified Rankin Scale) using multivariable models. Results We included 83 studies (31 unpublished) providing IPD for 1979 patients with COVID-19 and acute new-onset neurological disease. Encephalopathy (978 [49%] patients) and cerebrovascular events (506 [26%]) were the most common diagnoses. Respiratory and systemic symptoms preceded neurological features in 93% of patients; one third developed neurological disease after hospital admission. A poor outcome was more common in patients with cerebrovascular events (76% [95% CI 67–82]), than encephalopathy (54% [42–65]). Intensive care use was high (38% [35–41]) overall, and also greater in the cerebrovascular patients. In the cerebrovascular, but not encephalopathic patients, risk factors for poor outcome included breathlessness on admission and elevated D-dimer. Overall, 30-day mortality was 30% [27–32]. The hazard of death was comparatively lower for patients in the WHO European region. Interpretation Neurological COVID-19 disease poses a considerable burden in terms of disease outcomes and use of hospital resources from prolonged intensive care and inpatient admission; preliminary data suggest these may differ according to WHO regions and country income levels. The different risk factors for encephalopathy and stroke suggest different disease mechanisms which may be amenable to intervention, especially in those who develop neurological symptoms after hospital admission

Агитационное выщелачивание руды месторождения «Томтор» растворами серной и азотной кислот в атмосферных условиях

Experimental studies of various variants of agitation leaching of ore from the Tomtor deposit with dilute solutions of sulfuric and nitric acids under atmospheric conditions were carried out according to individual and combined two-stage schemes. It was found that in all leaching variants, REE, Sc, P and impurity elements (Fe, Al, Th) are recovered into the solution, and the degree of this extraction varies depending on the consumption of the main reagent and the leaching conditions. The results of the experiments showed that the practical application of the scheme of combined two-stage treatment of ores of the Tomtor deposit with nitric and sulfuric acids is practically impractical due to the low recovery rates of REE, Sc, P and impurity elements (Fe, Al, Th) in the solution.Проведены экспериментальные исследования различных вариантов агитационного выщелачивания руды месторождения «Томтор» разбавленными растворами серной и азотной кислот в атмосферных условиях по индивидуальным схемам и в качестве комбинированной двухстадийной схемы. Установлено, что при всех вариантах выщелачивания происходит излечение REE, Sc, Р и примесных элементов (Fe, Al, Th) в раствор, причем степень этого извлечения изменялась в зависимости от расхода основного реагента и условий выщелачивания. Результаты проведенных экспериментов показали, что практическое применение схемы комбинированной двухстадийной обработки руд месторождения «Томтор» азотной и серной кислотами практически нецелесообразно вследствие невысоких показателей извлечения REE, Sc, Р и примесных элементов (Fe, Al, Th) в раствор

Linearly polarized ytterbium-doped fiber laser in a pedestal design with aluminosilicate inner cladding

Ytterbium-doped polarization-maintaining fiber in a pedestal geometry is demonstrated using MCVD and a novel in-situ doping technique. The aluminosilicate pedestal layers minimize the thermal expansion mismatch against the silica outer cladding and permits complete freedom of location for the stress-applying parts in the fiber. A birefringence of 2.4×10-4 is experimentally determined. The fiber delivers linearly polarized laser exhibiting 79% slope efficiency with a polarization extinction ratio of 12 d

Erbium-doped multi-element fiber amplifiers for space-division multiplexing operations

Erbium-doped multi-element fiber (MEF) amplifiers have been fabricated to simultaneously amplify multiple transmission channels. MEF devices comprise of multiple single-core fibers (elements) combined in a common coating, with each element working as a single fiber in isolation. MEFs containing 3-elements and 7-elements have been fabricated and characterized. Each element of the fabricated MEFs provides nearly 32dB of gain with a noise figure of <5dB for an input signal level of -23dBm at 1530 nm. Different permutations of element pairs within the MEFs were checked for crosstalk and none was detected, confirming the simultaneous multi-channel amplification capabilities of MEFs