Field and current distributions and ac losses in superconducting strips

In this paper I discuss analytic and numerical calculations of the magnetic-field and sheet-current distributions in superconducting strips of width 2a and arbitrary thickness 2b at the center when the cross section is an ellipse, a rectangle, and a shape intermediate between these limits. Using critical-state theory, I use several methods to determine the functional dependence of the ac transport-current losses upon F = I/Ic, where I is the peak alternating current and Ic is the critical current, and I discuss how this dependence can be affected by the cross-sectional shape, aspect ratio, and a flux-density-dependent critical current density Jc(B).Comment: 13 pages, 11 figure

Geometry-dependent critical currents in superconducting nanocircuits

In this paper we calculate the critical currents in thin superconducting strips with sharp right-angle turns, 180-degree turnarounds, and more complicated geometries, where all the line widths are much smaller than the Pearl length $\Lambda = 2 \lambda^2/d$. We define the critical current as the current that reduces the Gibbs free-energy barrier to zero. We show that current crowding, which occurs whenever the current rounds a sharp turn, tends to reduce the critical current, but we also show that when the radius of curvature is less than the coherence length this effect is partially compensated by a radius-of-curvature effect. We propose several patterns with rounded corners to avoid critical-current reduction due to current crowding. These results are relevant to superconducting nanowire single-photon detectors, where they suggest a means of improving the bias conditions and reducing dark counts. These results also have relevance to normal-metal nanocircuits, as these patterns can reduce the electrical resistance, electromigration, and hot spots caused by nonuniform heating.Comment: 29 pages, 24 figure

Color pattern recognition with circular component whitening

Polychromatic object recognition based on circular whitening preprocessing of red-green-blue components and multichannel matched filtering is described. Computer simulations and experimental results are provided to facilitate recognizing a color target among objects of similar shape but with different color contents. Experimental results are obtained with an optical correlator with two spatial light modulators, one to introduce the scene and the second one to introduce the filter

Deep active learning for autonomous navigation.

Imitation learning refers to an agent's ability to mimic a desired behavior by learning from observations. A major challenge facing learning from demonstrations is to represent the demonstrations in a manner that is adequate for learning and efficient for real time decisions. Creating feature representations is especially challenging when extracted from high dimensional visual data. In this paper, we present a method for imitation learning from raw visual data. The proposed method is applied to a popular imitation learning domain that is relevant to a variety of real life applications; namely navigation. To create a training set, a teacher uses an optimal policy to perform a navigation task, and the actions taken are recorded along with visual footage from the first person perspective. Features are automatically extracted and used to learn a policy that mimics the teacher via a deep convolutional neural network. A trained agent can then predict an action to perform based on the scene it finds itself in. This method is generic, and the network is trained without knowledge of the task, targets or environment in which it is acting. Another common challenge in imitation learning is generalizing a policy over unseen situation in training data. To address this challenge, the learned policy is subsequently improved by employing active learning. While the agent is executing a task, it can query the teacher for the correct action to take in situations where it has low confidence. The active samples are added to the training set and used to update the initial policy. The proposed approach is demonstrated on 4 different tasks in a 3D simulated environment. The experiments show that an agent can effectively perform imitation learning from raw visual data for navigation tasks and that active learning can significantly improve the initial policy using a small number of samples. The simulated test bed facilitates reproduction of these results and comparison with other approaches

Анатомическое обоснование транспозиции грудоспинного нерва при невротизации поврежденных нервов плечевого сплетения

 The goal is to identify topographic, anatomic, and constitutional features of thoracodorsal and musculocutaneous nerves of brachial plexus.Materials and methods. Anthropometry of 45 corpses was carried out to determine growth; length of the trunk and upper extremities; circumference of neck, thoracic cage, shoulder and forearm; lateral dimensions of shoulders, thoracic cage and pelvis; anteroposterior size of thoracic cage; neck circumference. Morphometry of all brachial plexus components (length, thickness of nerves and angles of their origin) was performed after its  anatomic preparation.Results. The cephalic type of brachial plexus with participation of C4 spinal nerve was found in 7% of cases. The caudal type with inclusion of Th2 spinal nerve was found in 4% of cases. In 4% of cases, there was no musculocutaneous nerve, at the same time shoulder biceps innervates median nerve. In 93% of cases, the thoracodorsal nerve originates from posterior secondary bundle along lower posterior surface, in 7% it is an axillary nerve branch. Neck circumference is directly correlated with thoracodorsal nerve length: the larger the neck circumference is, the greater is the nerve length. In females, linear regression equations were derived, which allow estimating thoracodorsal nerve length knowing the thoracic cage width.Conclusion. The length of the thoracodorsal nerve determines the possibility of its transplantation into the musculocutaneous position. The size of neck circumference and, in females, the width of the thoracic cage, for reliability, should be used as external size biomarkers for donor and recipient nerves.  Цель. Выявление топографо-анатомических и  конституциональных особенностей грудоспинного и  мышечно-кожного нервов плечевого сплетения. Материалы и методы. Проведена антропометрия 45 трупов с определением роста, длины туловища и верхней конечности, окружности шеи, грудной клетки, плеча и предплечья, поперечных размеров плеч, грудной клетки и таза, переднезаднего размера грудной клетки, обхвата шеи.  После анатомического препарирования плечевого  сплетения проведена морфометрия всех его компонентов  (длины, толщины нервов и углов их отхождения).Результаты. Цефалический тип плечевого сплетения с  участием спинального нерва С4 установлен в 7%, каудальный тип с включением спинального нерва Th2 – в 4%  случаев. В 4% случаев отсутствует мышечно-кожный  нерв, двуглавую мышцу плеча при этом иннервирует  срединный нерв. В 93% случаев грудоспинной нерв отходит  от заднего вторичного пучка по задненижней поверхности,  в 7% это ветвь подмышечного нерва. Обхват шеи имеет  прямые значимые корреляции с длиной грудоспинного  нерва – чем больше обхват шеи, тем больше длина нерва. У женщин выведены уравнения линейной регрессии, на  основании которых можно вычислить предположительную  длину грудоспинного нерва при известном значении  ширины грудной клетки. Заключение. Длина грудоспинного нерва является  определяющей детерминантой возможности его пересадки  в позицию мышечно-кожного. В качестве внешнего  биомаркера размеров нерва-донора и нерва-реципиента  целесообразно использовать размеры обхвата шеи и для  достоверности у женщин – ширину грудной клетки.

Robin conditions on the Euclidean ball

Techniques are presented for calculating directly the scalar functional determinant on the Euclidean d-ball. General formulae are given for Dirichlet and Robin boundary conditions. The method involves a large mass asymptotic limit which is carried out in detail for d=2 and d=4 incidentally producing some specific summations and identities. Extensive use is made of the Watson-Kober summation formula.Comment: 36p,JyTex, misprints corrected and a section on the massive case adde

Incidence of Atrial Fibrillation in Patients with either Heart Failure or Acute Myocardial Infarction and Left Ventricular Dysfunction: A Cohort Study

<p>Abstract</p> <p>Background</p> <p>We examined the incidence of new-onset atrial fibrillation in patients with left ventricular dysfunction. Patients either had a recent myocardial infarction (with or without clinical heart failure) or symptomatic heart failure (without a recent MI). Patients were with and without treatment with the class III antiarrhythmic drug dofetilide over 36 months.</p> <p>Methods</p> <p>The Danish Investigations of Arrhythmia and Mortality ON Dofetilide (DIAMOND) studies included 2627 patients without atrial fibrillation at baseline, who were randomised to treatment with either dofetilide or placebo.</p> <p>Results</p> <p>The competing risk analyses estimated the cumulative incidences of atrial fibrillation during the 42 months of follow-up to be 9.6% in the placebo-treated heart failure-group, and 2.9% in the placebo-treated myocardial infarction-group.</p> <p>Cox proportional hazard regression found a 42% significant reduction in the incidence of new-onset AF when assigned to dofetilide compared to placebo (hazard ratio 0.58, 95% confidence interval 0.40-0.82) and there was no interaction with study (p = 0.89).</p> <p>In the heart failure-group, the incidence of atrial fibrillation was significantly reduced to 5.6% in the dofetilide-treated patients (hazard ratio 0.57, 95% confidence interval 0.38-0.86).</p> <p>In the myocardial infarction-group the incidence of atrial fibrillation was reduced to 1.7% with the administration of dofetilide. This reduction was however not significant (hazard ratio 0.61, 95% confidence interval 0.30-1.24).</p> <p>Conclusion</p> <p>In patients with left ventricular dysfunction the incidence of AF in 42 months was 9.6% in patients with heart failure and 2.9% in patients with a recent MI. Dofetilide significantly reduced the risk of developing atrial fibrillation compared to placebo in the entire study group and in the subgroup of patients with heart failure. The reduction in the subgroup with recent MI was not statistically significant, but the hazard ratio was similar to the hazard ratio for the heart failure patients, and there was no difference between the effect in the two studies (p = 0.89 for interaction).</p

Minimum length effects in black hole physics

We review the main consequences of the possible existence of a minimum measurable length, of the order of the Planck scale, on quantum effects occurring in black hole physics. In particular, we focus on the ensuing minimum mass for black holes and how modified dispersion relations affect the Hawking decay, both in four space-time dimensions and in models with extra spatial dimensions. In the latter case, we briefly discuss possible phenomenological signatures.Comment: 29 pages, 12 figures. To be published in "Quantum Aspects of Black Holes", ed. X. Calmet (Springer, 2014

Dapagliflozin in patients with heart failure and reduced ejection fraction

Background: In patients with type 2 diabetes, inhibitors of sodium–glucose cotransporter 2 (SGLT2) reduce the risk of a first hospitalization for heart failure, possibly through glucose-independent mechanisms. More data are needed regarding the effects of SGLT2 inhibitors in patients with established heart failure and a reduced ejection fraction, regardless of the presence or absence of type 2 diabetes. Methods: In this phase 3, placebo-controlled trial, we randomly assigned 4744 patients with New York Heart Association class II, III, or IV heart failure and an ejection fraction of 40% or less to receive either dapagliflozin (at a dose of 10 mg once daily) or placebo, in addition to recommended therapy. The primary outcome was a composite of worsening heart failure (hospitalization or an urgent visit resulting in intravenous therapy for heart failure) or cardiovascular death. Results: Over a median of 18.2 months, the primary outcome occurred in 386 of 2373 patients (16.3%) in the dapagliflozin group and in 502 of 2371 patients (21.2%) in the placebo group (hazard ratio, 0.74; 95% confidence interval [CI], 0.65 to 0.85; P&lt;0.001). A first worsening heart failure event occurred in 237 patients (10.0%) in the dapagliflozin group and in 326 patients (13.7%) in the placebo group (hazard ratio, 0.70; 95% CI, 0.59 to 0.83). Death from cardiovascular causes occurred in 227 patients (9.6%) in the dapagliflozin group and in 273 patients (11.5%) in the placebo group (hazard ratio, 0.82; 95% CI, 0.69 to 0.98); 276 patients (11.6%) and 329 patients (13.9%), respectively, died from any cause (hazard ratio, 0.83; 95% CI, 0.71 to 0.97). Findings in patients with diabetes were similar to those in patients without diabetes. The frequency of adverse events related to volume depletion, renal dysfunction, and hypoglycemia did not differ between treatment groups. Conclusions: Among patients with heart failure and a reduced ejection fraction, the risk of worsening heart failure or death from cardiovascular causes was lower among those who received dapagliflozin than among those who received placebo, regardless of the presence or absence of diabetes. (Funded by AstraZeneca; DAPA-HF ClinicalTrials.gov number, NCT03036124.

Effects of patient selection on the applicability of results from a randomised clinical trial (EORTC 10853) investigating breast-conserving therapy for DCIS

Selection of patients for randomised clinical trials may have a large impact on the applicability of the study results to the general population presenting the same disorder. However, clinical characteristics and outcome data on non-entered patients are usually not available. The effects of patient selection for the EORTC 10853 trial investigating the role of radiotherapy in breast conserving therapy for ductal carcinoma in situ have been studied, in an analysis of all patients treated for ductal carcinoma in situ in five participating institutes. The reasons for not entering patients were evaluated and treatment results of the randomised patients were compared to those not entered. A total of 910 patients were treated for ductal carcinoma in situ. Of these, 477 (52%) were ineligible, with the size of the lesion being the main reason for ineligibility (30% of all ductal carcinoma in situ). Of the 433 eligible patients, 278 (64%) were randomised into the trial. The main reasons for non-entry of eligible patients were either physicians' preference for one of the treatment arms (26%) or patients' refusal (9%). These percentages showed significant variation among the institutes. At 4 years follow-up, those patients not entered in the trial and treated with local excision and radiotherapy, had higher local recurrence rates than the patients randomised in the trial and treated with the same approach, (17 vs 2%, P=0.03). The patients treated with local excision alone had equal local recurrence rates (11% in both groups). Selection of patients may explain the differences in outcome of the randomised patients, and those not-entered. Thus, the results of this trial may not be applicable to all patients with ductal carcinoma in situ