Effect of external stresses on efficiency of dislocation sinks in BCC (Fe, V) and FCC (Cu) crystals

The efficiency of linear sinks for selfpoint defects (SPDs) elastically interacting (dislocations) and not interacting with sinks with the density of 3 × 1014 m–2 is calculated for BCC (Fe, V) and FCC (Cu) crystals at the temperature 293 K using the object kinetic Monte Carlo technique, depending on type and value of applied mechanical load (up to 200 MPa) and types of linear sinks. Full straight dislocations in slip systems [111](1 0), [111](11 ), [100](001), and [100](011) for Fe and V and [100](001) for Cu are considered for dislocation sinks (DSs). Orientations of noninteracting linear sinks (NILSs) coincide with those of DSs. Interaction of SPDs with internal (dislocation) and external stress fields is calculated within the framework of anisotropic linear theory of elasticity. Relative changes in efficiency of different codirectional linear sinks (either interacting or not interacting with SPDs) under action of applied stress are approximately identical under low stress. Radiation creep rates are calculated for the considered crystals under uniaxial stress in the stationary regime of Frenkel pairs generation. The creep rate strongly depends on the loading direction and Burgers vector of dislocations in Fe and V, and it is almost independent of these parameters in Cu. At the same generation rate of Frenkel pairs, the radiation creep rate averaged over all loading directions is significantly higher in BCC (Fe, V) crystals containing dislocations with the Burgers vector a/2〈111〉 than in FCC (Cu) crystals

Dislocation sinks efficiency for self-point defects in iron and vanadium crystals

The effect of the dislocations stress fields on their sink efficiency for self-point defects (interstitial atoms and vacancies) is studied in the temperature range of 293–1000 K and at the dislocation density values of 1 × 1012–3 × 1014 m−2 in body-centered cubic (BCC) iron and vanadium crystals. Straight screw and edge dislocations in 〈111〉{110}, 〈111〉{112}, 〈100〉{100}, and 〈100〉{110} slip systems are considered. Defect diffusion is simulated via the object kinetic Monte Carlo method. The energies of the interaction of defects with dislocations are calculated within the anisotropic linear theory of elasticity. The dislocation sink efficiency is analytically represented as a function of temperature and dislocation density

Endoscopic ultrasound—guided fine needle aspiration in the diagnosis of mediastinal masses of unknown origin

The ability of endosonography to diagnose a variety of gastrointestinal pathology has been significantly advanced with the introduction of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) biopsy. EUS-FNA technology can also be applied to the evaluation of non-GI disorders. The role of EUS-FNA to establish the diagnosis of unexplained mediastinal masses has not been previously described. The aim of this study was to determine the diagnostic accuracy, impact on subsequent workup, and role of EUS-FNA in treating mediastinal masses of unknown cause. METHODS : A total of 26 patients (15 men and 11 women, mean age 61 yr, range 39–77 yr) underwent EUS-FNA in patients presenting with unexplained mediastinal masses at four tertiary referral centers. Presenting symptoms included: chest pain (10 patients), dysphagia (eight), cough (seven), fever (six), night sweats (three), and no symptoms/abnormal x-ray (five patients). Five of 26 patients had prior history of cancer (three lung, one tracheal, and one esophageal). RESULTS : Final diagnosis using EUS-FNA, surgery, autopsy, other diagnostic study, or long-term follow-up was available in all patients. EUS-FNA results were classified under three disease categories: 1) infectious, 2) benign/inflammatory, and 3) malignant. Final diagnosis included infectious in five patents, benign/inflammatory in nine, and malignant in 12. EUS-FNA was successful in 21 of 26 patients (81%) for all disease categories (infectious 60%, benign/inflammatory 78%, and malignant 92%). EUS-FNA was successful in directing subsequent workup in 77% (20 of 26) and therapy in 73% (19 of 26). Mean EUS-FNA passes for adequate tissue sampling was lower of nonmalignant disease categories (3.0 and 3.4) versus malignant disease (4.4). No complications were seen during the course of this study. CONCLUSIONS : EUS-FNA in patients presenting with idiopathic mediastinal masses establishes the diagnosis in the vast majority of cases, particularly for those with malignant disease. The emergence of transesophageal EUS-FNA of the mediastinum provides the ability to alter subsequent workup and therapy, obviating the need for more invasive diagnostic studies such as thoracotomy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72588/1/j.1572-0241.2002.06023.x.pd

Real-time quantum error correction beyond break-even

The ambition of harnessing the quantum for computation is at odds with the fundamental phenomenon of decoherence. The purpose of quantum error correction (QEC) is to counteract the natural tendency of a complex system to decohere. This cooperative process, which requires participation of multiple quantum and classical components, creates a special type of dissipation that removes the entropy caused by the errors faster than the rate at which these errors corrupt the stored quantum information. Previous experimental attempts to engineer such a process faced an excessive generation of errors that overwhelmed the error-correcting capability of the process itself. Whether it is practically possible to utilize QEC for extending quantum coherence thus remains an open question. We answer it by demonstrating a fully stabilized and error-corrected logical qubit whose quantum coherence is significantly longer than that of all the imperfect quantum components involved in the QEC process, beating the best of them with a coherence gain of $G = 2.27 \pm 0.07$. We achieve this performance by combining innovations in several domains including the fabrication of superconducting quantum circuits and model-free reinforcement learning

This paper is a revision of a paper presented at the SPIE conference on Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine VIII

Abstract. Barrett's esophagus ͑BE͒ and associated adenocarcinoma have emerged as a major health care problem over the last two decades. Because of the widespread use of endoscopy, BE is being recognized increasingly in all Western countries. In clinical trials of endoscopic optical coherence tomography ͑EOCT͒, we defined certain image features that appear to be characteristic of precancerous ͑dys-plastic͒ mucosa: decreased scattering and disorganization in the microscopic morphology. The objective of the present work is to develop computer-aided diagnosis ͑CAD͒ algorithms that aid the detection of dysplasia in BE. The image dataset used in the present study was derived from a total of 405 EOCT images ͑13 patients͒ that were paired with highly correlated histologic sections of corresponding biopsies. Of these, 106 images were included in the study. The CAD algorithm used was based on a standard texture analysis method ͑center-symmetric auto-correlation͒. Using histology as the reference standard, this CAD algorithm had a sensitivity of 82%, specificity of 74%, and accuracy of 83%. CAD has the potential to quantify and standardize the diagnosis of dysplasia and allows high throughput image evaluation for EOCT screening applications. With further refinements, CAD could also improve the accuracy of EOCT identification of dysplasia in BE

Quark Potential in a Quark-Meson Plasma

We investigate quark potential by considering meson exchanges in the two flavor Nambu--Jona-Lasinio model at finite temperature and density. There are two kinds of oscillations in the chiral restoration phase, one is the Friedel oscillation due to the sharp quark Fermi surface at high density, and the other is the Yukawa oscillation driven by the complex meson poles at high temperature. The quark-meson plasma is strongly coupled in the temperature region $1\le T/T_c \lesssim 3$ with $T_c$ being the critical temperature of chiral phase transition. The maximum coupling in this region is located at the critical point.Comment: 8 pages and 8 figure