188 research outputs found

    Induced Lorentz-Violating Chern-Simons Term in QED: Uncovering Short Distance Interaction Terms in the Effective Lagrangian without the Shadow of Regularization

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    We show that the correctly evaluated effective Lagrangian should include short-distance interaction terms which have been avoided under the protection of usual regularization and must be properly identified and reinstated if regularization is to be removed. They have special physical and mathematical significance as well as restoring gauge invariance and suppressing divergence in the effective Lagrangian. The rich structure of the short-distance interaction terms can open up challenging opportunities where the conventional regularization with rigid structure is unavailable and inappropriate. It becomes clear that gauge invariance is preserved with or without regularization and therefore there is no Lorentz-Violating Chern-Simons term in QED.Comment: 5 pages. Talk presented at the Second Meeting on CPT and Lorentz Symmetry CPT'01, August 15-18, 2001, Bloomington, Indian

    Travel Seminar reflection: No Wall will stop our dreams of justice

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    This article was originally published in The Prophet -- a journal created by and for the students at the Boston University School of Theology (BUSTH) to amplify the voices of STH students by promoting and sharing a range of perspectives on matters of concern including, but not limited to, spiritual practices, faith communities and society, the nature of theology, and current affairs. It serves as a platform for STH students to share their academic work, theological reflections, and life experiences with one another and the wider community."How many stories have you heard about the U.S.-Mexico border? During the border trip, we had numerous chances to listen to stories from different volunteers and humanitarian activists. There is a particular one which touches my heart deeply. And I want to share this story with you... " [EXCERPT

    論古代女性形象和地位 : 以《說文解字》女部形容詞為研究中心

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    一個國家的文字往往反映其獨特的思想文化,漢代許慎的《說文解字》作為中國歷史上第一部有系統地考證字源的字書,當中對每個字的解釋都蘊藏了深刻的中國文化。本文以《說文解字》中的「女部」形容詞作為研究範圍。希望透過分析許慎為這些字所下的定義,配合歷史古籍,窺探古代女性的形象和地位,並嘗試探討背後的中國傳統文化思想。本文首先將《說文》「女部」可作為形容詞的字分為褒義及貶義,然後再按意義類別編排分類,其中褒義分為六大類,貶義分為五大類。由於《說文》「女部」中可以用來形容不同事物的字眾多,故本文只會抽取一部份來進行研究,詳細字義分類及解釋可參考附錄

    Metaphysical reduction of necessity : a modified account

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    This thesis investigates the metaphysical nature of necessity. My study focuses primarily on the reduction of metaphysical necessity and the question of whether a necessary truth can be reductively defined. Theodore Sider (2011) develops a new reductive account of metaphysical necessity. Unfortunately, the multiple realizability problem posed by Jonathan Schaffer (2013) undermines the credibility of Sider’s account. This underlies my motivation to search for a revised Siderian account of necessity. On this basis, I propose a modified version of Sider’s account and argue that analytic, natural-kind and micro-reduction truths are necessary truths if and only if they express the same states of affairs as logical truths. Since logical truths are necessary truths, analytic, natural-kind and micro-reduction truths are necessary truths as well. In this thesis, I will proceed as follows. Chapter 1 introduces Sider’s account of necessity. In particular, I focus on his analysis of the necessity of a micro-reduction truth. His analysis is largely constitutive of the notion of a metaphysical semantics and some associated notions. I reconstruct his analysis and articulate his metaphysical semantics and the associated notions. Chapter 2 presents and clarifies the multiple realizability problem of Schaffer. His critique shows that Sider’s metaphysical semantics cannot handle multiple realizability. Sider (2013e) refutes this claim by arguing that the multiple realizability problem is a problem for his analysis of the necessity of a micro-reduction truth, not for his metaphysical semantics itself. This is a good starting point to propound a modified account of necessity. Chapter 3 proposes and articulates my modified analysis of the necessity of a micro-reduction, where I show that the necessity of a micro-reduction truth can be reductively defined without appeal to Sider’s metaphysical semantics. I argue that analytic, natural-kind and microreduction truths are necessary truths if and only if they express the same states of affairs as logical truths. Logical truths are necessary and so are they. After that, I consider a potential objection to my modified account and attempt to respond to it

    Molecular and Electrophysiological Mechanisms Underlying Cardiac Arrhythmogenesis in Diabetes Mellitus.

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    This is the final version of the article. It first appeared from Hindawi via https://doi.org/10.1155/2016/2848759Diabetes is a common endocrine disorder with an ever increasing prevalence globally, placing significant burdens on our healthcare systems. It is associated with significant cardiovascular morbidities. One of the mechanisms by which it causes death is increasing the risk of cardiac arrhythmias. The aim of this article is to review the cardiac (ion channel abnormalities, electrophysiological and structural remodelling) and extracardiac factors (neural pathway remodelling) responsible for cardiac arrhythmogenesis in diabetes. It is concluded by an outline of molecular targets for future antiarrhythmic therapy for the diabetic population.GT was awarded a BBSRC Doctoral Training Award at the University of Cambridge for his PhD

    Isospin splitting in heavy baryons and mesons

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    A recent general analysis of light-baryon isospin splittings is updated and extended to charmed baryons. The measured Σc\Sigma_c and Ξc\Xi_c splittings stand out as being difficult to understand in terms of two-body forces alone. We also discuss heavy-light mesons; though the framework here is necessarily less general, we nevertheless obtain some predictions that are not strongly model-dependent.Comment: 12 pages REVTEX 3, plus 4 uuencoded ps figures, CMU-HEP93-

    Mechanisms of Electrical Activation and Conduction in the Gastrointestinal System: Lessons from Cardiac Electrophysiology.

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    This is the final version of the article. It first appeared from Frontiers via http://dx.doi.org/10.3389/fphys.2016.00182The gastrointestinal (GI) tract is an electrically excitable organ system containing multiple cell types, which coordinate electrical activity propagating through this tract. Disruption in its normal electrophysiology is observed in a number of GI motility disorders. However, this is not well characterized and the field of GI electrophysiology is much less developed compared to the cardiac field. The aim of this article is to use the established knowledge of cardiac electrophysiology to shed light on the mechanisms of electrical activation and propagation along the GI tract, and how abnormalities in these processes lead to motility disorders and suggest better treatment options based on this improved understanding. In the first part of the article, the ionic contributions to the generation of GI slow wave and the cardiac action potential (AP) are reviewed. Propagation of these electrical signals can be described by the core conductor theory in both systems. However, specifically for the GI tract, the following unique properties are observed: changes in slow wave frequency along its length, periods of quiescence, synchronization in short distances and desynchronization over long distances. These are best described by a coupled oscillator theory. Other differences include the diminished role of gap junctions in mediating this conduction in the GI tract compared to the heart. The electrophysiology of conditions such as gastroesophageal reflux disease and gastroparesis, and functional problems such as irritable bowel syndrome are discussed in detail, with reference to ion channel abnormalities and potential therapeutic targets. A deeper understanding of the molecular basis and physiological mechanisms underlying GI motility disorders will enable the development of better diagnostic and therapeutic tools and the advancement of this field.Croucher Foundatio

    Molecular and Electrophysiological Mechanisms Underlying Cardiac Arrhythmogenesis in Diabetes Mellitus

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    Diabetes is a common endocrine disorder with an ever increasing prevalence globally, placing significant burdens on our healthcare systems. It is associated with significant cardiovascular morbidities. One of the mechanisms by which it causes death is increasing the risk of cardiac arrhythmias. The aim of this article is to review the cardiac (ion channel abnormalities, electrophysiological and structural remodelling) and extracardiac factors (neural pathway remodelling) responsible for cardiac arrhythmogenesis in diabetes. It is concluded by an outline of molecular targets for future antiarrhythmic therapy for the diabetic population

    Electrophysiological Mechanisms of Bayés Syndrome: Insights from Clinical and Mouse Studies.

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    This is the final version of the article. It first appeared from Frontiers via https://doi.org/10.3389/fphys.2016.00188Bayés syndrome is an under-recognized clinical condition characterized by inter-atrial block (IAB). This is defined electrocardiographically as P-wave duration > 120 ms and can be categorized into first, second and third degree IAB. It can be caused by inflammatory conditions such as systemic sclerosis and rheumatoid arthritis, abnormal protein deposition in cardiac amyloidosis, or neoplastic processes invading the inter-atrial conduction system, such as primary cardiac lymphoma. It may arise transiently during volume overload, autonomic dysfunction or electrolyte disturbances from vomiting. In other patients without an obvious cause, the predisposing factors are diabetes mellitus, hypertensive heart disease, and hypercholesterolemia. IAB has a strong association with atrial arrhythmogenesis, left atrial enlargement (LAE), and electro-mechanical discordance, increasing the risk of cerebrovascular accidents as well as myocardial and mesenteric ischemia. The aim of this review article is to synthesize experimental evidence on the pathogenesis of IAB and its underlying molecular mechanisms. Current medical therapies include anti-fibrotic, anti-arrhythmic and anti-coagulation agents, whereas interventional options include atrial resynchronization therapy by single or multisite pacing. Future studies will be needed to elucidate the significance of the link between IAB and atrial tachyarrhythmias in patients with different underlying etiologies and optimize the management options in these populations.GT was awarded a BBSRC Doctoral Training Award at the University of Cambridge for his PhD
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