8 research outputs found
Josephson Currents in Quantum Hall Devices
We consider a simple model for an SNS Josephson junction in which the "normal
metal" is a section of a filling-factor integer quantum-Hall edge. We
provide analytic expressions for the current/phase relations to all orders in
the coupling between the superconductor and the quantum Hall edge modes, and
for all temperatures. Our conclusions are consistent with the earlier
perturbative study by Ma and Zyuzin [Europhysics Letters {\bf 21} 941-945
(1993)]: The Josephson current is independent of the distance between the
superconducting leads, and the upper bound on the maximum Josephson current is
inversely proportional to the perimeter of the Hall device.Comment: Revtex4. 22 pages 9 figures. Replaced version has minor typos fixed
and one added referenc
Theory of random matrices with strong level confinement: orthogonal polynomial approach
Strongly non-Gaussian ensembles of large random matrices possessing unitary
symmetry and logarithmic level repulsion are studied both in presence and
absence of hard edge in their energy spectra. Employing a theory of polynomials
orthogonal with respect to exponential weights we calculate with asymptotic
accuracy the two-point kernel over all distance scale, and show that in the
limit of large dimensions of random matrices the properly rescaled local
eigenvalue correlations are independent of level confinement while global
smoothed connected correlations depend on confinement potential only through
the endpoints of spectrum. We also obtain exact expressions for density of
levels, one- and two-point Green's functions, and prove that new universal
local relationship exists for suitably normalized and rescaled connected
two-point Green's function. Connection between structure of Szeg\"o function
entering strong polynomial asymptotics and mean-field equation is traced.Comment: 12 pages (latex), to appear in Physical Review
Shannon and Rényi mutual information in quantum critical spin chains
We study the Shannon mutual information in one-dimensional critical spin
chains, following a recent conjecture (Phys. Rev. Lett. 111, 017201 (2013)), as
well as R\'enyi generalizations of it. We combine conformal field theory
arguments with numerical computations in lattice discretizations with central
charge and . For a periodic system of length cut into two
parts of length and , all our results agree with the general
shape-dependence , where is a universal coefficient. For the free boson
CFT we show from general arguments that . At we conjecture a
result for . We perform extensive numerical computations in Ising chains
to confirm this, and also find , a nontrivial number
which we do not understand analytically. Open chains at and are
even more intriguing, with a shape-dependent logarithmic divergence of the
Shannon mutual information.Comment: 20 pages, 13 figures. v2: minor corrections, table added, expanded
appendices. v3: published versio
Advancing the Landscape of Multimessenger Science in the Next Decade
Engel K, Lewis T, Muzio MS, et al. Advancing the Landscape of Multimessenger Science in the Next Decade. arXiv:2203.10074. 2022.The last decade has brought about a profound transformation in multimessenger
science. Ten years ago, facilities had been built or were under construction
that would eventually discover the nature of objects in our universe could be
detected through multiple messengers. Nonetheless, multimessenger science was
hardly more than a dream. The rewards for our foresight were finally realized
through IceCube's discovery of the diffuse astrophysical neutrino flux, the
first observation of gravitational waves by LIGO, and the first joint
detections in gravitational waves and photons and in neutrinos and photons.
Today we live in the dawn of the multimessenger era. The successes of the
multimessenger campaigns of the last decade have pushed multimessenger science
to the forefront of priority science areas in both the particle physics and the
astrophysics communities. Multimessenger science provides new methods of
testing fundamental theories about the nature of matter and energy,
particularly in conditions that are not reproducible on Earth. This white paper
will present the science and facilities that will provide opportunities for the
particle physics community renew its commitment and maintain its leadership in
multimessenger science
Stoma-free Survival After Rectal Cancer Resection With Anastomotic Leakage: Development and Validation of a Prediction Model in a Large International Cohort.
Objective:To develop and validate a prediction model (STOMA score) for 1-year stoma-free survival in patients with rectal cancer (RC) with anastomotic leakage (AL).Background:AL after RC resection often results in a permanent stoma.Methods:This international retrospective cohort study (TENTACLE-Rectum) encompassed 216 participating centres and included patients who developed AL after RC surgery between 2014 and 2018. Clinically relevant predictors for 1-year stoma-free survival were included in uni and multivariable logistic regression models. The STOMA score was developed and internally validated in a cohort of patients operated between 2014 and 2017, with subsequent temporal validation in a 2018 cohort. The discriminative power and calibration of the models' performance were evaluated.Results:This study included 2499 patients with AL, 1954 in the development cohort and 545 in the validation cohort. Baseline characteristics were comparable. One-year stoma-free survival was 45.0% in the development cohort and 43.7% in the validation cohort. The following predictors were included in the STOMA score: sex, age, American Society of Anestesiologist classification, body mass index, clinical M-disease, neoadjuvant therapy, abdominal and transanal approach, primary defunctioning stoma, multivisceral resection, clinical setting in which AL was diagnosed, postoperative day of AL diagnosis, abdominal contamination, anastomotic defect circumference, bowel wall ischemia, anastomotic fistula, retraction, and reactivation leakage. The STOMA score showed good discrimination and calibration (c-index: 0.71, 95% CI: 0.66-0.76).Conclusions:The STOMA score consists of 18 clinically relevant factors and estimates the individual risk for 1-year stoma-free survival in patients with AL after RC surgery, which may improve patient counseling and give guidance when analyzing the efficacy of different treatment strategies in future studies
Stoma-free survival after anastomotic leak following rectal cancer resection: worldwide cohort of 2470 patients
Background: The optimal treatment of anastomotic leak after rectal cancer resection is unclear. This worldwide cohort study aimed to provide an overview of four treatment strategies applied. Methods: Patients from 216 centres and 45 countries with anastomotic leak after rectal cancer resection between 2014 and 2018 were included. Treatment was categorized as salvage surgery, faecal diversion with passive or active (vacuum) drainage, and no primary/secondary faecal diversion. The primary outcome was 1-year stoma-free survival. In addition, passive and active drainage were compared using propensity score matching (2: 1). Results: Of 2470 evaluable patients, 388 (16.0 per cent) underwent salvage surgery, 1524 (62.0 per cent) passive drainage, 278 (11.0 per cent) active drainage, and 280 (11.0 per cent) had no faecal diversion. One-year stoma-free survival rates were 13.7, 48.3, 48.2, and 65.4 per cent respectively. Propensity score matching resulted in 556 patients with passive and 278 with active drainage. There was no statistically significant difference between these groups in 1-year stoma-free survival (OR 0.95, 95 per cent c.i. 0.66 to 1.33), with a risk difference of -1.1 (95 per cent c.i. -9.0 to 7.0) per cent. After active drainage, more patients required secondary salvage surgery (OR 2.32, 1.49 to 3.59), prolonged hospital admission (an additional 6 (95 per cent c.i. 2 to 10) days), and ICU admission (OR 1.41, 1.02 to 1.94). Mean duration of leak healing did not differ significantly (an additional 12 (-28 to 52) days). Conclusion: Primary salvage surgery or omission of faecal diversion likely correspond to the most severe and least severe leaks respectively. In patients with diverted leaks, stoma-free survival did not differ statistically between passive and active drainage, although the increased risk of secondary salvage surgery and ICU admission suggests residual confounding