The Glue Around Quarks and the Interquark Potential

The quarks of quark models cannot be identified with the quarks of the QCD Lagrangian. We review the restrictions that gauge field theories place on any description of physical (colour) charges. A method to construct charged particles is presented. The solutions are applied to a variety of applications. Their Green's functions are shown to be free of infra-red divergences to all orders in perturbation theory. The interquark potential is analysed and it is shown that the interaction responsible for anti-screening results from the force between two separately gauge invariant constituent quarks. A fundamental limit on the applicability of quark models is identified.Comment: 4 pages, LaTeX, talk given at Montpellier meeting QCD9

Relationship between dairy cow genetic merit and profit on commercial spring calving dairy farms

peer-reviewedBecause not all animal factors influencing profitability can be included in total merit breeding indices for profitability, the association between animal total merit index and true profitability, taking cognisance of all factors associated with costs and revenues, is generally not known. One method to estimate such associations is at the herd level, associating herd average genetic merit with herd profitability. The objective of this study was to primarily relate herd average genetic merit for a range of traits, including the Irish total merit index, with indicators of performance, including profitability, using correlation and multiple regression analyses. Physical, genetic and financial performance data from 1131 Irish seasonal calving pasture-based dairy farms were available following edits; data on some herds were available for more than 1 year of the 3-year study period (2007 to 2009). Herd average economic breeding index (EBI) was associated with reduced herd average phenotypic milk yield but with greater milk composition, resulting in higher milk prices. Moderate positive correlations (0.26 to 0.61) existed between genetic merit for an individual trait and average herd performance for that trait (e.g. genetic merit for milk yield and average per cow milk yield). Following adjustment for year, stocking rate, herd size and quantity of purchased feed in the multiple regression analysis, average herd EBI was positively and linearly associated with net margin per cow and per litre as well as gross revenue output per cow and per litre. The change in net margin per cow per unit change in the total merit index was h1.94 (s.e.50.42), which was not different from the expectation of h2. This study, based on a large data set of commercial herds with accurate information on profitability and genetic merit, confirms that, after accounting for confounding factors, the change in herd profitability per unit change in herd genetic merit for the total merit index is within expectations

Risking It: An Examination of Risk Perception Amongst Obstetricians and Certified Professional Midwives in Missouri

The concept of risk is pervasive in contemporary discussions of childbirth –both amongst professionals and consumers. While risk is often presented as an objective entity, in reality it is an elusive concept to define, particularly within the context of maternity care. Since the nineteenth century, obstetricians and midwives have conceptualized the risks of birth differently. This thesis examines how two groups of practitioners in Missouri, obstetricians (OBs) and certified professional midwives (CPMs), perceive risk in pregnancy and childbirth. By combining archival investigation techniques with original qualitative research, I hope to demonstrate that risk in maternity care is far from a static concept. Rather, analyzing risk perception requires looking beyond individual knowledge systems to examine who it is that holds authoritative knowledge and how that knowledge drives definitions of risks and cultural understandings of what risks are acceptable during pregnancy and birth and what are not. After describing the history of maternity care in the United States, reviewing the relevant literature related to birth and risk perception, and presenting a qualitative study on the differences in risk perception between OBs and CPMs in Missouri, I move on to discuss the implications that differences and similarities in risk perception may have on the future of maternity care in Missouri

Asymptotic Dynamics in Quantum Field Theory

A crucial element of scattering theory and the LSZ reduction formula is the assumption that the coupling vanishes at large times. This is known not to hold for the theories of the Standard Model and in general such asymptotic dynamics is not well understood. We give a description of asymptotic dynamics in field theories which incorporates the important features of weak convergence and physical boundary conditions. Applications to theories with three and four point interactions are presented and the results are shown to be completely consistent with the results of perturbation theory.Comment: 18 pages, 3 figure