Rates of Nuclear Reactions in Solid-Like Stars

In stellar matter as cool and dense as the interior of a white dwarf, the Coulomb energies between neighboring nuclei are large compared to the kinetic energies of the nuclei. Each nucleus is constrained to vibrate about an equilibrium position, and the motion of the nuclei in the interior of a white dwarf is similar to the motion of the atoms in a solid or liquid. We propose a solid-state method for calculating the rate at which a nuclear reaction proceeds between two identical nuclei oscillating about adjacent lattice sites. An effective potential U(r) derived by analyzing small lattice vibrations is used to represent the influence of the Coulomb fields of the lattice on the motion of the two reacting nuclei. The wave function describing the relative motion of the two reacting particles is obtained by solving the Schrödinger equation containing the effective potential U(r). From this wave function, we derive an expression for the reaction rate. The rates of the p+p and C^(12)+C^(12) reactions calculated using this solid-state method are typically 1 to 10 orders of magnitude smaller than those calculated by the method previously suggested by Cameron

Status of the spawning biomass of the Pacific sardine, 1983-84

State law provides for the initiation of a fishery for Pacific sardines, Sardinops sagax caeruleus, when the spawning biomass of sardines reaches 20,000 short tons. Data from ichthyoplankton surveys, sea survey cruises, the mackerel fishery sampling program, and the live-bait fishery monitoring program are discussed with regard to an increase in population size. It appears that the spawning biomass of the northern stock of Pacific sardines remains below 20,000 tons. Legislation passed in 1983 which affects the incidental take and commercial use of sardines is also discussed. (9pp.

Neutron Stars

Several authors have suggested that the recently discovered extraterrestrial sources of x rays may be hot neutron stars. The plausibility of this suggestion, and in fact the likelihood that astronomers will ever be able to observe neutron stars by their x-ray emission, depend critically upon the cooling times of the hot stars

THE ECONOMICS OF MANAGING WILDLIFE DISEASE

The spread of infectious disease among and between wild domesticated animals has become a major problem worldwide. Upon analyzing the dynamics of wildlife growth and infection when the disease animals cannot be identified separately from healthy wildlife prior to the kill, we find that harvest-based strategies alone have no impact on disease transmission. Other controls that directly influence disease transmission and/or mortality are required. Next, we analyze the socially optimal management of infectious wildlife. The model is applied to the problem of bovine tuberculosis among Michigan white-tailed deer, with non-selective harvests and supplemental feeding being the control variables. Using a two-state linear control model, we find a two-dimensional singular path is optimal (as opposed to a more conventional bang-bang solution) as part of a cycle that results in the disease remaining endemic in the wildlife. This result follows from non-selective harvesting and intermittent wildlife productivity gains from supplemental feeding.Resource /Energy Economics and Policy,

A gravity model approach to forecasting tuberculosis transmission in cattle

Bovine tuberculosis (bTB) in cattle has caused significant economic losses to livestock producers and has proven difficult to eradicate. It is suspected that cattle movement across different farms and regions is one of the key factors of bTB transmission in the United States. Prior attempts to model the epidemiology of bTB infection within cattle to predict disease transmission have not adequately captured the behavioral aspects of trade. A better understanding of livestock trade patterns would help in predicting disease transmission and the associated economic effects. In this paper, we develop a gravity model of livestock trade and link it to an epidemiological model of bTB transmission, with the goal being that this information could lead to improved disease surveillance and management. Our findings suggest that feedbacks between jointly determined disease dynamics and trade system matter and should be considered together for efficient disease management.Bovine tuberculosis, Gravity model, disease management, Resource /Energy Economics and Policy,

Test of the gravitational redshift with stable clocks in eccentric orbits: application to Galileo satellites 5 and 6

The Einstein Equivalence Principle (EEP) is one of the foundations of the theory of General Relativity and several alternative theories of gravitation predict violations of the EEP. Experimental constraints on this fundamental principle of nature are therefore of paramount importance. The EEP can be split in three sub-principles: the Universality of Free Fall (UFF), the Local Lorentz Invariance (LLI) and the Local Position Invariance (LPI). In this paper we propose to use stable clocks in eccentric orbits to perform a test of the gravitational redshift, a consequence of the LPI. The best test to date was performed with the Gravity Probe A (GP-A) experiment in 1976 with an uncertainty of $1.4\times10^{-4}$. Our proposal considers the opportunity of using Galileo satellites 5 and 6 to improve on the GP-A test uncertainty. We show that considering realistic noise and systematic effects, and thanks to a highly eccentric orbit, it is possible to improve on the GP-A limit to an uncertainty around $(3-4)\times 10^{-5}$ after one year of integration of Galileo 5 and 6 data.Comment: 13 pages, 5 figures, accepted in Classical and Quantum Gravity as a Fast Track Communicatio

A sputtering derived atomic oxygen source for studying fast atom reactions

A technique for the generation of fast atomic oxygen was developed. These atoms are created by ion beam sputtering from metal oxide surfaces. Mass resolved ion beams at energies up to 60 KeV are produced for this purpose using a 150 cm isotope separator. Studies have shown that particles sputtered with 40 KeV Ar(+) on Ta2O5 were dominantly neutral and exclusively atomic. The atomic oxygen also resided exclusively in its 3P ground state. The translational energy distribution for these atoms peaked at ca 7 eV (the metal-oxygen bond energy). Additional measurements on V2O5 yielded a bimodal distribution with the lower energy peak at ca 5 eV coinciding reasonably well with the metal-oxygen bond energy. The 7 eV source was used to investigate fast oxygen atom reactions with the 2-butene stereoisomers. Relative excitation functions for H-abstraction and pi-bond reaction were measured with trans-2-butene. The abstraction channel, although of minor relative importance at thermal energy, becomes comparable to the addition channel at 0.9 eV and dominates the high-energy regime. Structural effects on the specific channels were also found to be important at high energy

A Model of Incentive Compatibility under Moral Hazard in Livestock Disease Outbreak Response

This paper uses a principal-agent model to examine incentive compatibility in the presence of information asymmetry between the government and individual producers. Prior models of livestock disease have not incorporated information asymmetry between livestock managers and social planners. By incorporating the asymmetry, we investigate the role of incentives in producer behavior that influences the duration and magnitude of a disease epidemic.livestock disease, moral hazard, principal-agent model, Institutional and Behavioral Economics,

Livestock Disease Indemnity Design When Moral Hazard is Followed by Adverse Selection

Averting or limiting the outbreak of infectious disease in domestic livestock herds is an economic and potential human health issue that involves both the government and individual livestock producers. Producers have private information about preventive biosecurity measures they adopt on their farms prior to outbreak (ex ante moral hazard), and following outbreak they possess private information about whether or not their herd is infected (ex post adverse selection). We investigate how indemnity payments can be designed to provide incentives to producers to invest in biosecurity and report infection to the government, while simultaneously addressing the information asymmetry between producers and the government. We show how addressing the adverse selection problem leads to a risk-sharing tradeoff in the moral hazard problem. We compare the relative magnitude of the first- and second-best levels of biosecurity investment and indemnity payments to further demonstrate the tradeoff between risk-sharing and efficiency, and we discuss the implications for status quo U.S. policy.Food Consumption/Nutrition/Food Safety, Livestock Production/Industries, Risk and Uncertainty,