Problem of the isochronous hairspring.

Thesis (M.A.)--Boston University This item was digitized by the Internet Archive.The system of the hairspring and balance wheel used to regulate watches and chronometers does not perform an exact simple harmonic motion. For the proper function of the watch the deviation from isochronism of the vibrations, caused by the reaction force at the fixed end point for any distortion of the spring, must be as small as possible. This reaction force is found to be correspondingly small if the shape of the hairspring is designed so that the reaction force at the end point is small. In theory only, perfect isochronism can be accomplished by a flat spring having one end free so that for any distortion of the sprang, the tangent to the end point moves parallel to itself; however, the free end spring cannot be realised in a watch. Phillips' solution to the problem primarily expresses that the reaction force at the end point is proportional to the displacement of the end point that would occur for a free spring. His solution is based on the problem of finding a possible curve such that the terminal point has a given trajectory or displacement, and simultaneously, at any point of the trajectory the tangent has an imposed direction. [TRUNCATED

Buffalo light water reactor calculations

An important objective of the light water reactor pressure vessel (LWRPV) surveillance dosimetry program is to validate and calibrate dosimetry and damage analysis techniques as well as to guide required neutron field calculations that are used to correlate changes in material properties with characteristics of the neutron irradiation field. As part of this activity, the Hanford Engineering Development Laboratory (HEDL) performed neutron flux calculations in a model of the light water test reactor of the Nuclear Science and Technology Facility of the State University of New York at Buffalo. The purpose of these calculations was to provide a consistent analysis base for projecting radiation damage produced by one reactor facility to that which would be incurred in another reactor facility

Outcomes of truncal vascular injuries in children.

BACKGROUND: Pediatric truncal vascular injuries occur infrequently and have a reported mortality rate of 30% to 50%. This report examines the demographics, mechanisms of injury, associated trauma, and outcome of patients presenting for the past 10 years at a single institution with truncal vascular injuries. METHODS: A retrospective review (1997-2006) of a pediatric trauma registry at a single institution was undertaken. RESULTS: Seventy-five truncal vascular injuries occurred in 57 patients (age, 12 +/- 3 years); the injury mechanisms were penetrating in 37%. Concomitant injuries occurred with 76%, 62%, and 43% of abdominal, thoracic, and neck vascular injuries, respectively. Nonvascular complications occurred more frequently in patients with abdominal vascular injuries who were hemodynamically unstable on presentation. All patients with thoracic vascular injuries presenting with hemodynamic instability died. In patients with neck vascular injuries, 1 of 2 patients who were hemodynamically unstable died, compared to 1 of 12 patients who died in those who presented hemodynamically stable. Overall survival was 75%. CONCLUSIONS: Survival and complications of pediatric truncal vascular injury are related to hemodynamic status at the time of presentation. Associated injuries are higher with trauma involving the abdomen

Neutron source strength in FFTF fuel as a function of irradiation

The neutron source strength associated with fuel irradiated in the FFTF reactor is important in determining the reactivity of the core when it is shut down or being refueled. The monitoring of subcritical reactivity for FFTF will be done with the Modified Source Multiplication (MSM) technique which requires an accurate knowledge of the neutron source strength in high exposure fuel elements replaced with fresh fuel elements in a shut down reactor. As a means of obtaining the most accurate source evaluations possible with existing nuclear data for FFTF irradiated fuel, a technique for generating one-group actinide cross sections for use in isotopic buildup and depletion codes was developed. A further objective of the work was to use the cross sections and recently evaluated spontaneous fission and (..cap alpha..,n) reaction neutron yield data to calculate the neutron source strength in typical compositions of FFTF-type fuel as a function of flux level and irradiation time and then to compare the results with those of a previous study to assess the differences in the nuclear data. This paper will highlight the important aspects of this study and present some results

Correlates and Determinants of Cardiorespiratory Fitness in Adults: a Systematic Review

Background Enhanced cardiorespiratory fitness (CRF) is now a well-established predictor of numerous adverse health outcomes. Knowledge about the pathways leading to enhanced CRF is essential for developing appropriate interventions. Hence, the aim of this review was to provide a detailed overview of the current state of research regarding individual factors associated with or influencing CRF among the general adult population. Methods We searched the PubMed, EMBASE, and Cochrane Library databases and also conducted a search for grey literature (Google Scholar). Eligible indicators of CRF were objectively assessed measures of CRF by submaximal or maximal exercise testing measured using treadmill or cycle ergometer tests. We included quantitative observational studies of the general adult population. Using a semi-quantitative approach, we compiled summary tables aggregating the study results for each potential correlate or determinant of CRF. Results We identified 3005 studies, 78 of which met the inclusion criteria. Almost all of these studies were conducted in high-income countries. Study quality scores assessing the risk of bias in the individual studies ranged from 40 to 100%. Male sex, age (inverse), education, socioeconomic status, ethnicity, body mass index (inverse), body weight (inverse), waist circumference, body fat (inverse), resting heart rate (inverse), C-reactive protein (inverse), smoking (inverse), alcohol consumption, and multiple measures of leisure-time physical activity were independently and consistently associated with CRF. Conclusions In synthesizing the current research on the correlates and determinants of CRF among adults, this systematic review identified gaps in the current understanding of factors influencing CRF. Beyond the scope of this review, environmental and interpersonal determinants should be further investigated.Peer Reviewe

A rare opportunity for conservative treatment in a case of blunt trauma to the supradiaphragmatic inferior vena cava

Injuries to the inferior vena cava (IVC) secondary to blunt trauma are rare and occur in only 1–10% of all blunt trauma patients. Management of these injuries has not been subjected to major studies, but several case reports and small retrospective studies have demonstrated that management can be tailored to the hemodynamic status of the patient; this is similar to the management of blunt liver injuries. Stable patients whose injuries have achieved local venous tamponade have been successfully treated without surgical intervention, while unstable patients require operative management. Regardless of patient status, however, IVC injuries are highly fatal with mortality rates between 70 and 90%. This report describes the case of a patient with a blunt traumatic injury to the supradiaphragmatic IVC with development of a pseudoaneurysm who was successfully managed conservatively

Socioeconomic Correlates and Determinants of Cardiorespiratory Fitness in the General Adult Population: a Systematic Review and Meta-Analysis

Background This review aims to (1) consolidate evidence regarding the association between socioeconomic status (SES) and cardiorespiratory fitness (CRF), (2) conduct a meta-analysis of the association between SES and CRF using methodologically comparable data, stratified by sex, and (3) test whether the association varies after adjustment for physical activity (PA). Methods A systematic review of studies from MEDLINE, EMBASE, Latin American and Caribbean Health Sciences (LILACS), Scientific Electronic Library Online (ScIELO), and Cochrane Library without time or language restrictions, which investigated associations between SES and CRF. Risk of bias within studies was assessed using a customized quality assessment tool. Results were summarized in table format and methodologically similar studies were synthesized using meta-analysis of Hedges’ g effect sizes. Synthesized results were appraised for cross-study bias. Results were tested for the impact of PA adjustment using meta-regression. Results Compared to individuals with low education, both men and women showed higher CRF among individuals with high education (men 0.12 [0.04–0.20], women 0.19 [0.02–0.36]), while participants with medium education showed no significant difference in CRF (men 0.03 [− 0.04–0.11], women 0.09 [− 0.03–0.21]). Adjustment for PA did not significantly impact the association between education and CRF. Conclusions There is fair evidence for an association between high levels of education and increased CRF. This could have implications for monitoring, of health target compliance and of chronic disease risk among higher risk populations, to detect and prevent non-communicable diseases (NCDs) and to diminish social health inequalities.Peer Reviewe