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.

Shear flow-interchange instability in nightside magnetotail causes auroral beads as a signature of substorm onset

A geometric wedge model of the near-earth nightside plasma sheet is used to derive a wave equation for low frequency shear flow-interchange waves which transmit $\vec{E} \times \vec{B}$ sheared zonal flows along magnetic flux tubes towards the ionosphere. Discrepancies with the wave equation result used in Kalmoni et al. (2015) for shear flow-ballooning instability are discussed. The shear flow-interchange instability appears to be responsible for substorm onset. The wedge wave equation is used to compute rough expressions for dispersion relations and local growth rates in the midnight region of the nightside magnetotail where the instability develops, forming the auroral beads characteristic of geomagnetic substorm onset. Stability analysis for the shear flow-interchange modes demonstrates that nonlinear analysis is necessary for quantitatively accurate results and determines the spatial scale on which the instability varies

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,

Was macht eine Sprache zur Wissenschaftssprache? : Synchrones und Diachrones

Wissenschaft ist das Suchen nach (neuen) Erkenntnissen. Die Erkenntnisse bzw. deren Resultate werden vom denkenden und erkennenden Menschen in Begriffe, in kognitive Einheiten, gefasst; damit diese Begriffe kommunizierbar werden, müssen sie mit Wörtern, sprachlichen Einheiten, benannt werden. Auf diese Weise kommt es (auch) zu fachlichen Terminologien. Ein Blick in die Geschichte der deutschen Sprache kann diese kognitiven und sprachlichen Prozesse illustrieren: Die deutsche Mystik des Mittelalters stellt die Sprecher/innen vor die Notwendigkeit, neue Erfahrungen, die der "Unio mystica", zu versprachlichen. Da eine deutsche Wissenschaftssprache sich erst im 18. Jahrhundert zu etablieren beginnt, ist die 'Fachsprache' der deutschen Mystik eine wichtige Vorstufe, die die Möglichkeiten, zu neuen Termini zu kommen, systematisiert. Wenn heute die deutschen Fachsprachen, wie es oft gefordert wird, vom Englischen abgelöst werden, gehen wichtige Erkenntnisquellen verloren