Positive and Normative Issues of Economic Growth with Infectious Disease

This paper uses a variant of the Lotka-Volterra system explaining the dynamic interaction between populations of infected and healthy individuals in which the demographic and epidemiological parameters (the net healthy birth rate, the death rate of the infected and the infection rate) are functions of economic variables and some simple economic growth models to examine deterministic growth paths of the system with an exogenous savings rate. Demographic-epidemiological parameters depend on productive capital which combined with healthy workers produces output. We find that there are generally multiple steady states. The system usually converges to a steady state in which the economy moderates the disease. If capital accumulation is set optimally to maximise welfare then there may be multiple steady states and optimal growth paths generally display four dimensional saddle point properties. Extensions of the framework to allow for density dependent infection, recovery from the disease and alternative social welfare functions are analysed.economic growth; infectious disease; dynamic optimal control.

A CASE STUDY ON THE APPLE HILL GROWER\u27S ASSOCIATION: AN AGRITOURISM AREA IN CAMINO, CA

The current research is a case study on the Apple Hill Grower’s Association (AHGA). The purpose of this case study was to gain a full understanding of the AHGA with a focus on the economic and social motivations of the original farmers to bring tourism to the farm. A majority of the past research on agritourism involves quantitative studies that are survey based; this study gives qualitative research perspective based on focus groups and personal interviews. In addition, past research is focused on other states (i.e. Michigan, Missouri, Montana) and countries (i.e Italy and Australia). This case study adds research to the agritourism book of knowledge in California. The subjects for this study were chosen through purposive sampling, a non-probability sampling technique that involves choosing experts highly involved in the research at hand (Kraus & Allen, 1997). It was important to have subjects highly involved in the culture of the AHGA and that were directly involved in the initial decisions to start an agritourism business. Therefore, seven participants were hand selected that were directly related to the beginning of the AHGA. One focus group and six semi-structured interviews were conducted with the subjects of this study. The data from the focus group and interviews were analyzed through the qualitative analysis process of “grounded theory”. The steps to grounded theory include: raw text, research concerns, relevant text, repeating ideas, themes, theoretical constructs, and theoretical narrative (Auerbach & Silverstein, 2003). Through this research, main themes emerged that were directly related to the objectives of this study. These main themes are as follows: survival, involvement, feuds, politics, complacency, factors for success, female gender role, less regulations, education of farmers, and negative impacts. From these main themes, many sub themes surfaced. The most prevalent theme of this study was survival, more particularly survival in reference to pear decline. The objective of this study was to explore the motivations of the original farmers of the AHGA to engage their farms in agritourism. The main motivation was to save their farm from the pear decline disease

Field theory of scaling lattice models. The Potts antiferromagnet

In contrast to what happens for ferromagnets, the lattice structure participates in a crucial way to determine existence and type of critical behaviour in antiferromagnetic systems. It is an interesting question to investigate how the memory of the lattice survives in the field theory describing a scaling antiferromagnet. We discuss this issue for the square lattice three-state Potts model, whose scaling limit as T->0 is argued to be described exactly by the sine-Gordon field theory at a specific value of the coupling. The solution of the scaling ferromagnetic case is recalled for comparison. The field theory describing the crossover from antiferromagnetic to ferromagnetic behaviour is also introduced.Comment: 11 pages, to appear in the proceedings of the NATO Advanced Research Workshop on Statistical Field Theories, Como 18-23 June 200

Huertos, diversidad y alimentación en una zona de transición ecológica del estado de México

The study of the home gardens in Mexico is important. It represents an alternative food supplement of the families in rural and urban zones. In the zone ecological transitional State of Mexico the diversity of vegetal species in the home gardens is wide, due to the interaction of geographic, climatic, soil, environmental and ecological conditions. The products obtained have diverse uses: nutritional, social, ritual and commercial, being the most important that for subsistence and the social relation

Critical points of coupled vector-Ising systems. Exact results

We show that scale-invariant scattering theory allows to exactly determine the critical points of two-dimensional systems with coupled O(N) and Ising order parameters. The results are obtained for N continuous and include criticality of the loop gas type. In particular, for N = 1 we exhibit three critical lines intersecting at the Berezinskii Kosterlitz Thouless transition point of the Gaussian model and related to the Z4 symmetry of the isotropic Ashkin Teller model. For N = 2 we classify the critical points that can arise in the XY-Ising model and provide exact answers about the critical exponents of the fully frustrated XY model

The Coester Line in Relativistic Mean Field Nuclear Matter

The Walecka model contains essentially two parameters that are associated with the Lorentz scalar (S) and vector (V) interactions. These parameters are related to a two-body interaction consisting of S and V, imposing the condition that the two-body binding energy is fixed. We have obtained a set of different values for the nuclear matter binding energies at equilibrium densities. We investigated the existence of a linear correlation between $B_N$ and $\rho_0$, claimed to be universal for nonrelativistic systems and usually known as the Coester line, and found an approximate linear correlation only if $V?S$ remains constant. It is shown that the relativistic content of the model, which is related to the strength of $V?S$, is responsible for the shift of the Coester line to the empirical region of nuclear matter saturation.Comment: 7 pages, 5 figure

Finite temperature results on the 2d Ising model with mixed perturbation

A numerical study of finite temperature features of thermodynamical observables is performed for the lattice 2d Ising model. Our results support the conjecture that the Finite Size Scaling analysis employed in the study of integrable perturbation of Conformal Field Theory is still valid in the present case, where a non-integrable perturbation is considered.Comment: 9 pages, Latex, added references and improved introductio

Finite Nuclei in a Relativistic Mean-Field Model with Derivative Couplings

We study finite nuclei, at the mean-field level, using the Zimanyi-Moskowski model and one of its variations (the ZM3 model). We calculate energy levels and ground-state properties in nuclei where the mean-field approach is reliable. The role played by the spin-orbit potential in sorting out mean-field model descriptions is emphasized.Comment: 17 pages, 9 figures, 30 kbytes. Uses EPSF.TEX. To appear in Zeit. f. Phys. A (Hadrons and Nuclei

Proposal to improve the behaviour of self-energy contributions to the S-matrix

A simple modification of the definition of the S-matrix is proposed. It is expected that the divergences related to nonzero self-energies are considerably milder with the modified definition than with the usual one. This conjecture is verified in a few examples using perturbation theory. The proposed formula is written in terms of the total Hamiltonian operator and a free Hamiltonian operator and is therefore applicable in any case when these Hamiltonian operators are known.Comment: 24 pages, 1 figure; v2: revised version; v3: section 3 improved. Accepted for publication in Central European Journal of Physics; v4: minor text misprints correcte