Design of Tools for Press-countersinking or Dimpling 0.040-inch-thick-24S-T Sheet

A set of dimpling tools was designed for 0.040-inch 24S-T sheet and flush-type rivets 1/8 inch in diameter with 100 degree countersunk heads. The dimples produced under different conditions of pressure, sheet thickness, and drill diameter are presented as cross-sectional photographs magnified 20 times. The most satisfactory values for the dimpling tools were found to be: maximum punch diameter, 0.231 inch; maximum die diameter, 0.223 inch; maximum mandrel diameter, 0.128 inch; dimple angle, 100 degree; punch springback angle, 1 1/2 degree; and die springback angle, 2 degree

The Elastic Constants for Wrought Aluminum Alloys

There are several constants which have been devised as numerical representations of the behavior of metals under the action of loadings which stress the metal within the range of elastic action. Some of these constants, such as Young's modulus of elasticity in tension and compression, shearing modulus of elasticity, and Poisson's ratio, are regularly used in engineering calculations. Precise tests and experience indicate that these elastic constants are practically unaffected by many of the factors which influence the other mechanical properties of materials and that a few careful determinations under properly controlled conditions are more useful and reliable than many determinations made under less favorable conditions. It is the purpose of this paper to outline the methods employed by the Aluminum Research Laboratories for the determination of some of these elastic constants, to list the values that have been determined for some of the wrought aluminum alloys, and to indicate the variations in the values that may be expected for some of the commercial products of these alloys

Takotsubo Syndrome: Uncovering Myths and Misconceptions

PURPOSE OF REVIEW Takotsubo syndrome (TTS) was described in Japan 3 decades ago to affect predominately postmenopausal women after emotional stress. This history is the basis of commonly held beliefs which may contribute to the underdiagnosis and misperception of TTS. RECENT FINDINGS TTS affects not only women, but can be present in both sexes, and can appear in children as well as in the elderly. TTS is characterized by unique clinical characteristics with morphological variants, and incurs a substantial risk for recurrent events and adverse outcomes. Physical triggers are more common than emotional triggers and are major disease determinants. TTS seems not to be completely transient as patients report ongoing chest pain, dyspnea, or fatigue even after months of the acute event. Knowledge of the clinical features and outcomes of TTS patients has evolved substantially over the past decades. The heterogeneous appearance of TTS needs to be recognized in all medical disciplines to maximize therapy and improve outcomes

Spontaneous Coronary Artery Dissection: A Rare Event?

Spontaneous coronary artery dissection is an infrequent cause of acute coronary syndrome with comparable clinical features. Previously considered a rare disease, recent scientific interest has revealed spontaneous coronary artery dissection as an important differential diagnosis of acute coronary syndrome, especially in young women, during pregnancy or postpartum, and in patients with fibromuscular dysplasia or other arteriopathies. However, there remain many uncertainties regarding pathophysiology, risk factors, acute treatment, and optimal long-term management. The aim of this review is to summarize current scientific evidence on epidemiology, management, and outcomes

Propagation of a Solitary Fission Wave

Reaction-diffusion phenomena are encountered in an astonishing array of natural systems. Under the right conditions, self stabilizing reaction waves can arise that will propagate at constant velocity. Numerical studies have shown that fission waves of this type are also possible and that they exhibit soliton like properties. Here, we derive the conditions required for a solitary fission wave to propagate at constant velocity. The results place strict conditions on the shapes of the flux, diffusive, and reactive profiles that would be required for such a phenomenon to persist, and this condition would apply to other reaction diffusion phenomena as well. Numerical simulations are used to confirm the results and show that solitary fission waves fall into a bistable class of reaction diffusion phenomena. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729927]United States Nuclear Regulatory Commission NRC-38-08-946Mechanical Engineerin

Clinical characteristics and outcomes of patients with takotsubo syndrome versus spontaneous coronary artery dissection

BACKGROUND Takotsubo syndrome (TTS) and spontaneous coronary artery dissection (SCAD) are now increasingly recognized. Both conditions predominantly affect females; however, the exact pathophysiology remains unclear. Large multi-center databases can help elucidate the underlying mechanism and optimize treatments to improve outcomes by allowing us to compare features and outcomes of patients with TTS and patients with SCAD. METHODS Takotsubo syndrome patients were enrolled from the International Takotsubo Registry and compared to SCAD patients from the Canadian Spontaneous Coronary Artery Dissection Cohort Study. In total 2098 TTS patients and 750 SCAD patients were included in the present study. RESULTS More than 85% of patients in both groups were females. TTS patients were older compared to SCAD patients. Physical triggers were more common in TTS patients, while emotional triggers and non-identifiable triggering events were more common in SCAD patients. Left ventricular ejection fraction was more impaired in TTS compared to SCAD. TTS patients had more major cardiovascular risk factors, while SCAD patients had a higher rate of migraines and anxiety disorders than TTS patients. Thirty-day mortality was significantly higher in TTS patients, while 30-day stroke rates were comparable between groups. CONCLUSIONS These findings suggest that women are at higher risk for TTS and SCAD compared to men, which should be considered in the differential diagnosis of those presenting with acute coronary syndrome. Additionally, emotional stressors play a significant role in triggering events particularly in younger women suffering from SCAD. The present findings may help clinicians better differentiate these 2 entities and aid in the appropriate risk stratification, diagnosis, and management. TRIAL REGISTRATION ClinicalTrials.gov no. NCT01947621

Clinical correlates and prognostic impact of neurologic disorders in Takotsubo syndrome

Cardiac alterations are frequently observed after acute neurological disorders. Takotsubo syndrome (TTS) represents an acute heart failure syndrome and is increasingly recognized as part of the spectrum of cardiac complications observed after neurological disorders. A systematic investigation of TTS patients with neurological disorders has not been conducted yet. The aim of the study was to expand insights regarding neurological disease entities triggering TTS and to investigate the clinical profile and outcomes of TTS patients after primary neurological disorders. The International Takotsubo Registry is an observational multicenter collaborative effort of 45 centers in 14 countries (ClinicalTrials.gov, identifier NCT01947621). All patients in the registry fulfilled International Takotsubo Diagnostic Criteria. For the present study, patients were included if complete information on acute neurological disorders were available. 2402 patients in whom complete information on acute neurological status were available were analyzed. In 161 patients (6.7%) an acute neurological disorder was identified as the preceding triggering factor. The most common neurological disorders were seizures, intracranial hemorrhage, and ischemic stroke. Time from neurological symptoms to TTS diagnosis was <= 2 days in 87.3% of cases. TTS patients with neurological disorders were younger, had a lower female predominance, fewer cardiac symptoms, lower left ventricular ejection fraction, and higher levels of cardiac biomarkers. TTS patients with neurological disorders had a 3.2-fold increased odds of in-hospital mortality compared to TTS patients without neurological disorders. In this large-scale study, 1 out of 15 TTS patients had an acute neurological condition as the underlying triggering factor. Our data emphasize that a wide spectrum of neurological diseases ranging from benign to life-threatening encompass TTS. The high rates of adverse events highlight the need for clinical awareness

Psychosocial and clinical characteristics of a patient with Takotsubo syndrome and her healthy monozygotic twin: a case report

Background: Takotsubo syndrome (TTS) is an acute heart failure syndrome characterized by transient left ventricular dysfunction, increased myocardial biomarkers, and electrocardiographic changes. Symptoms of TTS are similar to those of acute coronary syndromes, but there is often no significant coronary stenosis. Although emotional and physical stressors are often reported as having triggered TTS, the pathogenesis is largely unknown. To address this issue, we comprehensively characterized a monozygous pair of twin sisters, one of whom experienced TTS. Case summary: The 60-year-old Caucasian monozygotic female twins with and without TTS were examined at the University Hospital Zurich in Switzerland. The twins completed questionnaires and clinical interviews assessing several sociopsychological factors. The twin sister with TTS exhibited higher levels of anxiety, vital exhaustion, social inhibition, and alexithymia, and lower levels of quality of and meaning in life. She was given the diagnoses of social phobia, adjustment disorder, specific anxiety disorder, obsessive-compulsive personality disorder, and an accentuated anxiety-avoidant personality disorder. Additionally, the twin with TTS experienced more-and also more severe-stressors involving life-threatening and dangerous situations over the life course. Discussion: These monozygous female twins with and without TTS differed in several notable aspects of their psychological functioning, psychiatric status, personality, and lifetime stressor exposure. The results thus highlight several factors, besides genetic components, that may play an important role in the pathogenesis of TTS. Looking forward, larger studies using experimental and longitudinal designs are needed to elucidate the role that psychosocial factors play in TTS. Keywords: Case report; Monozygotic twins; Psychology; Stress-induced cardiomyopathy; Takotsubo syndrom