Spin glasses are disordered magnetic materials, and it is hard to find a less promising candidate to serve as a focal point of complexity studies, much less as the object of thousands of investigations. On first inspection, they don't seem particularly exciting. Although they're a type of magnet, they're not very good at being magnetic. Metallic spin glasses are unremarkable conductors, and insulating spin glasses are fairly useless as practical insulators. This introductory chapter provides an overview of why spin glasses might be of interest to the reader if they are not a physicist but are interested in any of a variety of other problems outside physics, or more generally in the field of complexity itself. It explores those features of spin glasses that have attracted, in turn, condensed matter and statistical physicists, complexity scientists, and mathematicians and applied mathematicians of various sorts.
Spin glasses are disordered magnetic systems that have led to the development of mathematical tools with an array of real-world applications, from airline scheduling to neural networks. This book offers the most concise, engaging, and accessible introduction to the subject, fully explaining what spin glasses are, why they are important, and how they are opening up new ways of thinking about complexity. This one-of-a-kind guide to spin glasses begins by explaining the fundamentals of order and symmetry in condensed matter physics and how spin glasses fit into and modify this framework. The book then explores how spin-glass concepts and ideas have found applications in areas as diverse as computational complexity, biological and artificial neural networks, protein folding, immune response maturation, combinatorial optimization, and social network modeling. Providing an essential overview of the history, science, and growing significance of this exciting field, the book also features a forward-looking discussion of what spin glasses may teach us in the future about complex systems. This is a useful book for students and practitioners in the natural and social sciences, with new material even for the experts.
Purpose: To investigate the diagnostic performance of a cine magnetic resonance imaging (MRI) sequence in the visualization and detection of impaired bowel peristalsis. Materials and Methods:In all, 91 consecutive patients (mean age 45 years) were prospectively examined on a 1.5 T system and stratified into a surgery group (n ¼ 22) and a nonsurgery group (n ¼ 69). A coronal fast imaging with steady-state precession (TrueFISP) sequence with 30 acquisitions per slice covered the abdomen in 10-15 slices each 7-12 mm thick (temporal resolution: 6-8 sec per frame). Image evaluation for reduced bowel peristalsis and relevant bowel stenosis was compared to surgical findings or clinical follow-up.Results: Cine MRI reached 96% accuracy (94% sensitivity; 100% specificity) in detecting a relevant reduction in bowel peristalsis and 85% of relevant stenosis was identified in the surgery group. Twenty of 69 patients of the nonsurgery group showed reduced peristalsis on cine MR which was attributed to underlying disease; 49/69 patients in this group had no findings on cine MR and were uneventfully followed up.Conclusion: Cine MRI of the bowel provides functional information of bowel passage. The visualization of a reduction in peristalsis may improve the assessment of the functional impact of suspected bowel adhesions or stenosis. Standard bowel MR protocols can be easily complemented by cine MR, extending scan time by <4 minutes. STANDARD MAGNETIC RESONANCE IMAGING (MRI)of the abdomen includes a set of various sequences that commonly produce static images covering the whole abdominal cavity. To enhance image quality antispasmodics like butylscopolamine bromide are given to reduce the intrinsic bowel motility. Additionally, there are multiple ways of distending the bowel lumen in order to improve the visibility of the bowel wall. This technique, which is denoted MR enteroclysis, MR enterography, or MR colonography, allows for visualizing the small or large bowel to enable radiologists identify underlying pathologies like bowel wall inflammation, thickening, or stenosis. The technical development of MRI as well as the improvement of imaging protocols rendered MRI of the small and large bowel the primary method in imaging inflammatory bowel disease such as Crohn's disease or ulcerative colitis. However, certain disease entities such as bowel adhesions in patients with chronic bowel obstruction are not successfully approached by MRI or computed tomography (CT) so far. On the other hand, small bowel stenosis, independent of its underlying pathology, is often adequately detected by conventional MRI but its functional impact on bowel passage cannot be assessed. This is mainly due to the fact that most of the up-to-date bowel imaging is performed by static images and intentional reduction of peristalsis by antispasmodics. In other fields like cardiac and thoracic imaging the implementation of functional imaging transformed primarily static, morphologic imaging studies into a method that allows for acquiring functional parameters, eg...
The chapter explains that up to this point the discussion has centered on some basic concepts of condensed matter physics as viewed through the illustrative lenses of familiar systems: liquids, crystals, and glasses. The chapter now turns to another important class of materials: magnetic systems, which are regarded as materials possessing properties that can be altered or manipulated through the application of an external magnetic field. The chapter introduces the basics of solid state magnetism, starting with the quantum mechanical property of spin, and showing how the familiar phenomenon of ferromagnetism—as well as the less familiar but equally important ones of antiferromagnetism and paramagnetism—arises. This is a necessary prelude to understanding the idea of what a spin glass is.
This randomized controlled study shows that correct interpretation of 2D imaging does not differ in students trained with either 3D or 2D.
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