Notes on The Feynman Checkerboard Problem

The Feynman checkerboard problem is an interesting path integral approach to the Dirac equation in `1+1' dimensions. I compare two approaches reported in the literature and show how they may be reconciled. Some physical insights may be gleaned from this approach.Comment: 9 page

The Regulation of Deep-Well Injection: A Changing Environment Beneath the Surface

Deep-well injection has been a mainstay of hazardous waste disposal for over 70 years. Before the U.S. Environmental Protection Agency (EPA) was created, there were concerns as to the proper place for deep-well injection as a waste management technique. Over the years, environmentalists have been concerned with the potential for contamination of drinking water supplies from deep-well injection. Industry has also shown concern about -deep-well injection, but from a different perspective. To industry, deep-well injection is a precious, limited resource. It is within this context that Congress and the EPA have regulated deep-well injection. It is that process of regulation and the development of deep-well injection policy which is the focus of this article

Intermediate-term results of a nonresectional dynamic repair technique in 662 patients with mitral valve prolapse and mitral regurgitation

ObjectiveA nonresectional technique has been developed for repair of mitral leaflet prolapse causing mitral regurgitation. Polytetrafluoroethylene chordae are used for correction of edge misalignment of the prolapsed mitral leaflet. New chordal length is adjusted during progressive left ventricular inflation to systolic pressure. Annular sizing is determined dynamically after leaflet edge alignment is accomplished to produce an optimal zone of predefined leaflet apposition. The aim of this study was to document the 8- to 10-year durability of this nonresectional approach.MethodsFrom 1983 through 2008, 1121 consecutive patients had mitral valve repair on one service. Of these, 662 had repair of mitral leaflet prolapse. From 1983 until 1998, standard quadratic leaflet resection/plication was used in 72 (11.1%) patients, similar but smaller resection in 93 (14.1%) patients, and then smaller resection and polytetrafluoroethylene chordae in 24 (3.7%) patients. All received Puig–Massana fully flexible rings (Shiley, Inc, Irvine, Calif). After 1998, no leaflet resections or valve replacements have been performed regardless of leaflet size in 566 consecutive patients. Of the 662 patients, the mean age was 62.6 ± 14.1 years, and 424 (64.1%) patients were male. Coronary artery disease was present in 147 (22.2%) patients and 33 (5.0%) had prior coronary artery bypass. Leaflets corrected were as follows: anterior, 152 (23.0%) patients; posterior, 427 (64.5%); and both, 83 (12.5%) Common pathologic characteristics of prolapsing valves were as follows: myxomatous, 332 (50.2%) patients, degenerative, 83 (12.5%), ischemic, 31 (4.7%), and rheumatic, 29 (4.4%).ResultsPerioperative mortality was 2.9% (19/662) overall and 0.49% (2/414) for isolated repair. Freedom from reoperation at 10 years (Kaplan–Meier) was 90.1% and freedom from significant mitral regurgitation (echocardiography) was 93.9%.ConclusionsThis study confirms that mitral regurgitation from mitral leaflet prolapse can be repaired in all cases by a nonresectional technique provided that accurate dynamic evaluation of chordal length and annular sizing is achieved. The intermediate-term results are durable

The Passing Regiment : March And Two - Step

https://digitalcommons.library.umaine.edu/mmb-ps/2684/thumbnail.jp

This Court Doth Keep All England in Quiet : Star Chamber and Public Expression in Prerevolutionary England, 1625–1641

The abrupt legislative destruction of the Court of Star Chamber in the summer of 1641 is generally understood as a reaction against the perceived abuses of prerogative government during the decade of Charles I\u27s personal rule. The conception of the court as an \u27extra-legal\u27 tribunal (or as a legitimate court that had exceeded its jurisdictional mandate) emerges from the constitutional debate about the limits of executive authority that played out over in Parliament, in the press, in the pulpit, in the courts, and on the battlefields of seventeenth-century England. Too narrow a focus on the question of the court\u27s legitimacy, however, impedes our ability to understand the historical Court of Star Chamber and the significant role it played in policing the boundaries of public expression in prerevolutionary England. This thesis attempts to capture an image of the Court of Star Chamber as it existed during the late 1620s and early 1630s by identifying the individuals who formed the \u27core\u27 of the court and by examining the court\u27s decisions in a series of representative cases. This study exposes the fault lines of political allegiance, religious persuasion, and judicial temperament that divided the members of the court. On the other hand, it suggests that the men who sat as judges in the Court of Star Chamber shared a commitment to the preservation of the established order in church and state—a commitment fundamentally out of place in a society that was entering a period of radical change

Energy Balance During a Self-Sufficient, Multistage Ultramarathon

Endurance athletes are recommended to maintain energy balance and ensure adequate energy availability (EA) so that endurance performance is not compromised. Purpose: Describe and evaluate the energy balance of an athlete competing in a self-sufficient, multistage ultramarathon (MSU). Methods: A male endurance athlete (age 35 years; height 183.0 cm; body mass 78.4 kg; VO2max 66 ml/kg/min) volunteered to take part in this observational case study prior to competing in the Marathon des Sables (MdS) 2016. The subject self-reported energy intake (EI) by reviewing his dietary plan following each stage. Basal metabolic rate (BMR) was estimated prior to the MdS based on fat-free mass. Distance and moving speed were recorded using a GPS device throughout the race. Exercise energy expenditure (EEE) was calculated using the GPS device algorithm. Total energy expenditure (TEE) was calculated by adding the athlete’s BMR to the recorded EEE. Energy balance was calculated by subtracting EI from TEE. Results: Mean daily EI was 2946 ± 358 kcal and daily EEE was 3006 ± 1030 kcal. This resulted in a total energy deficit of 9609 kcal with a daily energy deficit of 1922 ± 952 kcal/day. The athlete did not report any subjective feelings of hunger at any point during the event. Conclusions: The athlete did not consume enough calories to meet estimated energy requirements, resulting in a negative energy balance and low EA throughout the event. Relying on subjective perception of hunger to modulate energy intake is an ineffective strategy during a MSU