Topological Schr\"odinger cats: Non-local quantum superpositions of topological defects

Topological defects (such as monopoles, vortex lines, or domain walls) mark locations where disparate choices of a broken symmetry vacuum elsewhere in the system lead to irreconcilable differences. They are energetically costly (the energy density in their core reaches that of the prior symmetric vacuum) but topologically stable (the whole manifold would have to be rearranged to get rid of the defect). We show how, in a paradigmatic model of a quantum phase transition, a topological defect can be put in a non-local superposition, so that - in a region large compared to the size of its core - the order parameter of the system is "undecided" by being in a quantum superposition of conflicting choices of the broken symmetry. We demonstrate how to exhibit such a "Schr\"odinger kink" by devising a version of a double-slit experiment suitable for topological defects. Coherence detectable in such experiments will be suppressed as a consequence of interaction with the environment. We analyze environment-induced decoherence and discuss its role in symmetry breaking.Comment: 7 pages, 4 figure

Prevalence of extracranial cerebrovascular disease in Chinese patients with coronary artery disease

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Effect of screening abdominal ultrasound examination on the decision to pursue advanced diagnostic tests and treatment in dogs with neurologic disease.

BackgroundAbdominal ultrasound examinations (AUS) are commonly performed before advanced neurodiagnostics to screen for diseases that might affect diagnostic plans and prognosis.ObjectivesDescribe the type and frequency of abnormalities found by AUS in dogs presenting with a neurological condition, identify risk factors associated with abnormalities, and evaluate treatment decisions based on findings.AnimalsSeven hundred and fifty-nine hospitalized dogs.MethodsRetrospective study. Medical records of dogs presented from 2007 to 2009 for neurologic disease were searched for signalment, neuroanatomic localization, and AUS findings. Whether dogs had advanced neurodiagnostics and treatment was analyzed.ResultsFifty-eight percent of dogs had abnormal findings on AUS. Probability of abnormalities increased with age (P < 0.001). Nondachshund breeds had higher probability of abnormal AUS than dachshunds (odds ratio [OR] = 1.87). Eleven percent of dogs did not have advanced neurodiagnostics and in 1.3%, this was because of abnormal AUS. Dogs with ultrasonographic abnormalities were less likely than dogs without to have advanced neurodiagnostics (OR = 0.3 [95% confidence interval [CI]: 0.17, 0.52]), however, the probability of performing advanced diagnostics was high regardless of normal (OR = 0.95 [95% CI: 0.92, 0.97]) or abnormal (OR = 0.85 [95% CI: 0.81, 0.88]) AUS. Treatment was more often pursued in small dogs and less often in dogs with brain disease.Conclusions and clinical importanceFindings from screening AUS had a small negative effect on the likelihood of pursuing advanced neurodiagnostics. Although it should be included in the extracranial diagnostic workup in dogs with significant history or physical examination abnormalities, AUS is considered a low-yield diagnostic test in young dogs and dachshunds

Endogenous repair by the activation of cell survival signalling cascades during the early stages of rat parkinsonism.

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Software testing education and training in Hong Kong

While the use of computer applications is widely spread in every business and, hence, the reliability of software is critical, it is believed that many organizations involved in software development do not take software testing sufficiently seriously as an important task. It is worthwhile to find out how far organizations are carrying out software testing in a systematic and structured manner or still taking on an ad-hoc approach. A survey was conducted to understand the software testing practices and the level of related education and training in Hong Kong. It was found that most testing team members did not have formal training in software testing. University curricula generally did not prepare graduates with enough coverage in software testing. It is proposed that a review of the current software engineering curricula in the universities to examine the coverage of software testing will be useful to the development of quality software. © 2005 IEEE.published_or_final_versio

Hydrogen peroxide augments the injury effect of iron on the isolated rat heart and cardiomyocytes

2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Stenting in small coronary arteries: initial experience with the Gianturco-roubin II stent

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Value of micro-CT for monitoring spinal microvascular changes after chronic spinal cord compression

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In-hospital and long-term clinical outcome following percutaneous transluminal coronary angioplasty in octogenarians

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In-hospital and long-term clinical outcome following percutaneous transluminal coronary angioplasty in octogenarians

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