Variational structure of Luttinger-Ward formalism and bold diagrammatic expansion for Euclidean lattice field theory

The Luttinger-Ward functional was proposed more than five decades ago to provide a link between static and dynamic quantities in a quantum many-body system. Despite its widespread usage, the derivation of the Luttinger-Ward functional remains valid only in the formal sense, and even the very existence of this functional has been challenged by recent numerical evidence. In a simpler and yet highly relevant regime, namely the Euclidean lattice field theory, we rigorously prove that the Luttinger-Ward functional is a well-defined universal functional over all physical Green's functions. Using the Luttinger-Ward functional, the free energy can be variationally minimized with respect to Green's functions in its domain. We then derive the widely used bold diagrammatic expansion rigorously, without relying on formal arguments such as partial resummation of bare diagrams to infinite order

Development, Survival and Phenology of the Sweetclover Weevil Parasitoid, \u3ci\u3ePygostolus Falcatus\u3c/i\u3e (Hymenoptera: Braconidae)

Biennial sweetclovers were widely used for soil improvement and as for- ages in the first half of the 1900s. The introduction of the sweetclover weevil, Sitona cylindricollis, caused a drastic decline in sweetclover acreage. In North Dakota, yellow sweetclover, Melilotus officinalis, is still the legume of choice on organic farms. In an effort to control the weevil, the thelyotokous parasitoid Pygostolus falcatus was imported. Parasitoids were studied for temperature-dependent development, and adult longevity as influenced by temperature and availability of provisions. Development from egg to adult at 15, 20, 25 and 30°C was 58, 28, 22 and 21 d, respectively. No parasitoids were reared out at 10°C, although diapausing first instars were present. Longevity of adult parasitoids provided honey, water, sweetclover and sweet- clover weevils at 15, 20, 25 and 30°C was 29, 22, 12 and 6 d, respectively. Adults provided the following combinations of provisions at 25°C survived for: nothing-2 d; water-2 d; honey-4 d; honey and water - 6 d; honey, water and sweetclover - 11 d; honey, water, sweetclover and hosts - 12 d. Field cage releases and a degree-day model developed for the parasitoid demonstrated that poor synchrony between P. falcatus and the sweetclover weevil hinders its usefulness as a biological control agent

A Long-Term Analysis of Changes in Farm Size and Financial Performance

This paper examined the changing structure of farms in Kansas. Specifically, changes in farm size, farm type, financial performance, and economies of size were examined using five-year moving averages from 1973 to 2007. Convergence analysis was used to determine whether small farms are catching up to larger farms or whether the difference in performance between these two groups of farms was widening. Results suggested that the gaps between the small farms and large farms have widened.Economies of Size, Financial Performance, Farm Management, Production Economics, D21,

Marginal Propensity to Consume for a Sample of Kansas Farms

This paper examined the marginal propensity to consume (MPC) for a sample of Kansas farms. Sensitivity of estimated MPCs to the use of accrual net farm income, net cash farm income, and the inclusion of off-farm income was also examined. Results yielded a range of short-run MPCs from 0.011 to 0.015. Statistical tests suggested that the income coefficients used to compute short-run MPCs were not statistically different.Farm Consumption, Habit Persistence, Agricultural Finance, Farm Management, E21,