Confinement interaction in nonlinear generalizations of the Wick-Cutkosky model

We consider nonlinear-mediating-field generalizations of the Wick-Cutkosky model. Using an iterative approach and eliminating the mediating field by means of the covariant Green function we arrive at a Lagrangian density containing many-point time-nonlocal interaction terms. In low-order approximations of $\phi^3{+}\phi^4$ theory we obtain the usual two-current interaction as well as a three-current interaction of a confining type. The same result is obtained without approximation for a version of the dipole model. The transition to the Hamiltonian formalism and subsequent canonical quantization is performed with time non-locality taken into account approximately. A relativistic three-particle wave equation is derived variationally by using a three-particle Fock space trial state. The non-relativistic limit of this equation is obtained and its properties are analyzed and discussed.Comment: 15 pages, 1 figure, LaTe

Variational Derivation of Relativistic Fermion-Antifermion Wave Equations in QED

We present a variational method for deriving relativistic two-fermion wave equations in a Hamiltonian formulation of QED. A reformulation of QED is performed, in which covariant Green functions are used to solve for the electromagnetic field in terms of the fermion fields. The resulting modified Hamiltonian contains the photon propagator directly. The reformulation permits one to use a simple Fock-space variational trial state to derive relativistic fermion-antifermion wave equations from the corresponding quantum field theory. We verify that the energy eigenvalues obtained from the wave equation agree with known results for positronium.Comment: 25 pages, accepted in Journal of Mathematical Physics (2004

Exact spinor-scalar bound states in a QFT with scalar interactions

We study two-particle systems in a model quantum field theory, in which scalar particles and spinor particles interact via a mediating scalar field. The Lagrangian of the model is reformulated by using covariant Green's functions to solve for the mediating field in terms of the particle fields. This results in a Hamiltonian in which the mediating-field propagator appears directly in the interaction term. It is shown that exact two-particle eigenstates of the Hamiltonian can be determined. The resulting relativistic fermion-boson equation is shown to have Dirac and Klein-Gordon one-particle limits. Analytic solutions for the bound state energy spectrum are obtained for the case of massless mediating fields.Comment: 12 pages, RevTeX, 1 figur

Exact two-particle eigenstates in partially reduced QED

We consider a reformulation of QED in which covariant Green functions are used to solve for the electromagnetic field in terms of the fermion fields. It is shown that exact few-fermion eigenstates of the resulting Hamiltonian can be obtained in the canonical equal-time formalism for the case where there are no free photons. These eigenstates lead to two- and three-body Dirac-like equations with electromagnetic interactions. Perturbative and some numerical solutions of the two-body equations are presented for positronium and muonium-like systems, for various strengths of the coupling.Comment: 33 pages, LaTex 2.09, 4 figures in EPS forma

The Changing Face of Wisconsin DairyFarms: A summary of PATS research on structural change in the 1990s

Medium-sized, diversified, family-labor farms1 have long defined the structure of dairy farming in “America’s Dairyland.” The red barns, silos, farm houses, and fields of hay, grain, and pasture associated with these operations have given rise to the state’s distinctive pastoral landscapes. As family businesses these farms have been successful enough to provide their operators with “middle-class” standards of living. Nationally, in the 20th century, Wisconsin’s dairy sector produced more milk and especially more cheese than any other state in the U.S. Among Wisconsin residents, much cultural pride stems from the state’s preeminence in dairying — car license plates bear the motto “America’s Dairyland,” while sports fans are particularly infamous for donning foam “cheeseheads” to identify themselves as from Wisconsin. Over the last 50 years the dairy farm sector in Wisconsin has witnessed considerable changes in the size of their milking herds, use of production technologies and management practices, and mix of livestock and cropping enterprises. Despite these changes, most dairy farm operations have typically remained at a scale such that they are still operated and managed predominantly by farm household members. Indeed, until quite recently, Wisconsin only had a handful of large dairy farms that rely heavily on hired labor. At the same time, it has typically had fewer “very small” dairy farms typical of some other midwestern or southern states. The distinctive character of Wisconsin dairy farming has been attributed to the state’s unique political, cultural, and socioeconomic history (Gilbert and Akor, 1986)

Aspiration therapy for the treatment of obesity: 4-year results of a multicenter randomized controlled trial.

BackgroundThe AspireAssist is the first Food and Drug Administration-approved endoluminal device indicated for treatment of class II and III obesity.ObjectivesWe earlier reported 1-year results of the PATHWAY study. Here, we report 4-year outcomes.SettingUnited States-based, 10-center, randomized controlled trial involving 171 participants with the treatment arm receiving Aspiration Therapy (AT) plus Lifestyle Therapy and the control arm receiving Lifestyle Therapy (2:1 randomization).MethodsAT participants were permitted to continue in the study for an additional year up to a maximum of 5 years providing they maintained at least 10% total weight loss (TWL) from baseline at each year end. For AT participants who continued the study, 5 medical monitoring visits were provided at weeks 60, 68, 76, 90, and 104 and thereafter once every 13 weeks up to week 260. Exclusion criteria were a history of eating disorder or evidence of eating disorder on a validated questionnaire. Follow-up weight, quality of life, and co-morbidities were compared with the baseline levels. In addition, rates of serious adverse event, persistent fistula, withdrawal, and A-tube replacement were reported. All analyses were performed using a per-protocol analysis.ResultsOf the 82 AT participants who completed 1 year, 58 continued to this phase of the trial. Mean baseline body mass index of these 58 patients was 41.6 ± 4.5 kg/m2. At the end of first year (at the beginning of the follow-up study), these 58 patients had a body mass index of 34.1 ± 5.4 kg/m2 and had achieved an 18.3 ± 8.0% TWL. On a per protocol basis, patients experienced 14.2%, 15.3%, 16.6%, and 18.7% TWL at 1, 2, 3, and 4 years, respectively (P < .01 for all). Forty of 58 patients (69%) achieved at least 10% TWL at 4 years or at time of study withdrawal. Improvements in quality of life scores and select cardiometabolic parameters were also maintained through 4 years. There were 2 serious adverse events reported in the second through fourth years, both of which resolved with removal or replacement of the A tube. Two persistent fistulas required surgical repair, representing approximately 2% of all tube removals. There were no clinically significant metabolic or electrolytes disorders observed, nor any evidence for development of any eating disorders.ConclusionsThe results of this midterm study have shown that AT is a safe, effective, and durable weight loss alternative for people with class II and III obesity and who are willing to commit to using the therapy and adhere to adjustments in eating behavior

QUALITATIVE AND QUANTITATIVE ANALYSIS OF MUSCLE POWER

Muscle power is one mechanical quantity that is not clearly understood by many coaches and teachers of human movement. This is probably due to an inadequate differentiation between the concepts of work/energy and of power. Thus we will begin this paper with a discussion of these concepts. The analysis of the vertical jump as a measure of work, energy, and power will also be discussed

Use and Implications of BovineSomatotropin for the Wisconsin Dairy Sector in the 1990s

Seven years have passed since the U.S. government approved the commercial use of recombinant bovine somatotropin (rBST), a synthetic relative of a naturally-occurring growth hormone that stimulates milk production in cows. Prior to approval, national controversy over rBST, more popularly known as BGH (bovine growth hormone), raged for almost a decade (Barham, 1996). Opponents and proponents alike envisioned rBST as a juggernaut technology, one that would change the dairy industry in dramatic ways, first and foremost by substantially raising herd productivity and overall milk production and then perhaps by driving away consumers from dairy products. With these concerns in mind, opponents also believed that rBST’s effects would drive tens of thousands of (smaller-scale) dairy farmers out of business by both depressing milk prices and rendering small-scale producers less competitive. Meanwhile, proponents hailed the technology as a valuable management tool for improving herd performance and the efficiency of dairy farms of any scale. At the peak of the controversy, the U.S. Congress debated whether to overturn the Food and Drug Administration’s approval, and the Senate demanded a special, full-length report by the Office of Management and Budget (1994) assessing the potential impacts of rBST on the U.S. dairy industry and society. Given the intensity of the debate in the early 1990s, it is noteworthy that rBST’s seventh anniversary as a commercial product passed with hardly a mention from any of the erstwhile protagonists, even in Wisconsin which had been at the center of the national tempest. These “after-the-storm” conditions reflect the fact that markets and regulations shaping rBST use have been relatively stable for several years now, with most demand-side uncertainties surrounding U.S. consumer reaction largely dissipated, at least for the time being. Instead of chaos and disruption, what emerged quickly in Wisconsin, and in some other major dairy producing states (including California and Minnesota), were segmented markets for fluid milk as well as for some processed products (cheeses, soft products, etc.). These market niches have held steady or perhaps receded in certain instances. Generally, retailers and processors, respectively, use signs above the dairy case and product labels to signal to consumers the availability of dairy products from cows not treated with rBST. For dairy farmers, this marketplace stability means that rBST adoption decisions are now probably based on their own adoption preferences, production strategies, other farm-level factors, and the local presence (or lack of) segmented markets for dairy products rather than uncertainties about consumer reaction