The embedding of the spacetime in five dimensions: an extension of Campbell-Magaard theorem

We extend Campbell-Magaard embedding theorem by proving that any n-dimensional semi-Riemannian manifold can be locally embedded in an (n+1)-dimensional Einstein space. We work out some examples of application of the theorem and discuss its relevance in the context of modern higher-dimensional spacetime theories.Comment: 22pages, Revte

The embedding of the spacetime in five-dimensional spaces with arbitrary non-degenerate Ricci tensor

We discuss and prove a theorem which asserts that any n-dimensional semi-Riemannian manifold can be locally embedded in a (n+1)-dimensional space with a non-degenerate Ricci tensor which is equal, up to a local analytic diffeomorphism, to the Ricci tensor of an arbitrary specified space. This may be regarded as a further extension of the Campbell-Magaard theorem. We highlight the significance of embedding theorems of increasing degrees of generality in the context of higher dimensional spacetimes theories and illustrate the new theorem by establishing the embedding of a general class of Ricci-flat spacetimes

The lens and source of the optical Einstein ring gravitational lens ER 0047-2808

(Abridged) We perform a detailed analysis of the optical gravitational lens ER 0047-2808 imaged with WFPC2 on the Hubble Space Telescope. Using software specifically designed for the analysis of resolved gravitational lens systems, we focus on how the image alone can constrain the mass distribution in the lens galaxy. We find the data are of sufficient quality to strongly constrain the lens model with no a priori assumptions about the source. Using a variety of mass models, we find statistically acceptable results for elliptical isothermal-like models with an Einstein radius of 1.17''. An elliptical power-law model (Sigma \propto R^-beta) for the surface mass density favours a slope slightly steeper than isothermal with beta = 1.08 +/- 0.03. Other models including a constant M/L, pure NFW halo and (surprisingly) an isothermal sphere with external shear are ruled out by the data. We find the galaxy light profile can only be fit with a Sersic plus point source model. The resulting total M/L_B contained within the images is 4.7 h_65 +/-0.3. In addition, we find the luminous matter is aligned with the total mass distribution within a few degrees. The source, reconstructed by the software, is revealed to have two bright regions, with an unresolved component inside the caustic and a resolved component straddling a fold caustic. The angular size of the entire source is approx. 0.1'' and its (unlensed) Lyman-alpha flux is 3 x 10^-17 erg/s/cm^2.Comment: 13 pages, 5 figures. Revised version accepted for publication in MNRA

PERCEPTIONS OF LEAFY SPURGE BY PUBLIC LAND MANAGERS, LOCAL DECISION MAKERS, AND RANCH OPERATORS

A survey of 459 ranchers, 56 local decision makers, and 50 public land managers (565 total) was conducted to evaluate managerial, institutional, and social factors that may affect the rate and extent of implementation of various leafy spurge (Euphorbia esula L.) controls. The study focused on a five-county region in Montana, North Dakota, South Dakota, and Wyoming. The questionnaire focused on weed management in general and specifically on the perceptions and attitudes of ranchers, land managers, and local decision makers who have been directly and indirectly affected by leafy spurge.leafy spurge, weed management, rancher opinion, public land manager opinions., Farm Management, Resource /Energy Economics and Policy,

Classical Nucleation Theory of the One-Component Plasma

We investigate the crystallization rate of a one-component plasma (OCP) in the context of classical nucleation theory. From our derivation of the free energy of an arbitrary distribution of solid clusters embedded in a liquid phase, we derive the steady-state nucleation rate of an OCP as a function of the Coulomb coupling parameter. Our result for the rate is in accord with recent molecular dynamics simulations, but it is greater than that of previous analytical estimates by many orders of magnitude. Further molecular dynamics simulations of the nucleation rate of a supercooled liquid OCP for several values of the coupling parameter would clarify the physics of this process.Comment: 6 pages, 1 figure, accepted by PR

ECONOMIC ANALYSIS OF CONTROLLING LEAFY SPURGE WITH SHEEP

Leafy spurge (Euphorbia esula L.), a widely established exotic, noxious, perennial weed, is a major threat to rangeland and wildland in the Upper Great Plains. Chemical, biological, and cultural control methods have limitations in their applicability and effectiveness in treating leafy spurge. However, many of the constraints prohibiting the use of herbicides, tillage, and biological controls do not apply to sheep grazing. Sheep grazing, while known to be effective in controlling leafy spurge since the 1930s, has lacked widespread adoption as a leafy spurge control. A deterministic, bioeconomic model, incorporating relationships between sheep grazing and leafy spurge control, grass recovery, and forage use by cattle, was developed to evaluate the economic viability of using sheep to control leafy spurge. Discounted annual control costs were compared to discounted annual control benefits over 5-year, 10-year, and 15-year periods. Various scenarios were developed depicting likely situations involving adopting a sheep enterprise or leasing sheep for leafy spurge control. Situational factors considered included fencing expenses, debt considerations, grazing values, infestation size, infestation canopy cover, rangeland productivity, and flock performance. Two levels of flock profitability, one based on a level of proficiency achieved by sheep ranches and one substantially lower than typically achieved in the sheep industry, represented best-case and worst-case situations, respectively. In the best-case situations, using sheep to control leafy spurge was economical in all of the control scenarios examined. However, in the worst-case situations, economics of using sheep to control leafy spurge were mixed across the scenarios examined. Leafy spurge control with poor sheep management, high fence expense, and unproductive rangeland generally was not economical. However, situations with low fencing costs, moderately productive rangeland, and poor sheep management resulted in less economic loss than no treatment. Although many of the key relationships tying leafy spurge control to grazing benefits remain unquantified, the economics of sheep grazing were positive across many of the scenarios evaluated in this study. Actual returns from leafy spurge control for most ranchers will likely fall between the two extremes examined. As a precaution, careful evaluation using site- and rancher-specific inputs would be recommended before implementing sheep grazing as a leafy spurge control method.Leafy Spurge, Weed Control, Sheep Grazing, Economics, Farm Management, Resource /Energy Economics and Policy,

RANCH OPERATORS' PERCEPTIONS OF LEAFY SPURGE

A survey of 459 ranchers was conducted to evaluate managerial, institutional, and social factors that may affect the rate and extent of implementation of various leafy spurge (Euphorbia esula L.) controls in a five-county region in Montana, North Dakota, South Dakota, and Wyoming. Ranchers returned 187 questionnaires. Weeds were considered a greater problem for ranchers with leafy spurge than for those without leafy spurge; however, even among ranchers with leafy spurge, there was strong agreement that other ranching issues were of greater concern. Over 65 percent of the respondents indicated that weeds on their ranch were a `minor problem.' Leafy spurge was ranked as the most important weed. Nearly 60 percent of ranchers felt that using herbicides, biological agents, and grazing animals on leafy spurge were economical; however, only 25 percent of ranchers with leafy spurge felt those controls were `very effective.' A majority of ranchers with leafy spurge indicated plans to treat their infestations with herbicides and biological agents in the future. Reasons for not using various leafy spurge controls fell into environmental, educational, and financial categories. Ranchers depend heavily on their county extension agents and local weed control officers for information on weed control. Information on the effectiveness and economics of various controls was most requested by ranchers. The responses of ranchers to various statements on weed and range management indicated that ranchers, as a group, are generally very concerned about weeds in rangeland. Respondents generally felt it makes economic sense to control weeds in rangeland, and felt very strongly that not enough was being done to control weeds on public land. Ranchers realize the difficulty in controlling leafy spurge, but indicated they are still planning on fighting the weed in the future. Financial and educational constraints to adopting and using leafy spurge controls could be abated through university and governmental educational programs and through cost-share or other financial assistance.leafy spurge, control, rancher opinion, Farm Management, Resource /Energy Economics and Policy,

Series solutions for a static scalar potential in a Salam-Sezgin Supergravitational hybrid braneworld

The static potential for a massless scalar field shares the essential features of the scalar gravitational mode in a tensorial perturbation analysis about the background solution. Using the fluxbrane construction of [8] we calculate the lowest order of the static potential of a massless scalar field on a thin brane using series solutions to the scalar field's Klein Gordon equation and we find that it has the same form as Newton's Law of Gravity. We claim our method will in general provide a quick and useful check that one may use to see if their model will recover Newton's Law to lowest order on the brane.Comment: 5 pages, no figure

FEASIBILITY OF A SHEEP COOPERATIVE FOR GRAZING LEAFY SPURGE

This report presents an economic feasibility study of a 5,000 head, cooperatively owned, sheep operation for leafy spurge control. The objectives were 1) determine the return on investment of the cooperative, 2) determine the proposed structure of the cooperative, and 3) ascertain the amount of capital investment required by members in the cooperative. Three sheep flock management alternatives were initially considered for the cooperative. These were 1) winter lambing, 2) spring lambing, and 3) fall lambing. The fall lambing scenario was determined to be infeasible because of logistics associated with gathering and transportation of pregnant ewes and lack of grazing pressure on leafy spurge throughout the grazing season. The total capital investment per ewe for the winter lambing scenario was more than the spring lambing scenario - - $301 and$216, respectively. The expected net income generated by the winter lambing scenario was negative. The minimum break-even lamb selling price or lambs sold per ewe for the winter lambing scenario was $84.10/cwt and 1.33, respectively. The spring lambing scenario returned$124,000 annually. The minimum breakeven lamb selling price or lambs sold per ewe for the spring lambing scenario was $59.51/cwt and 0.94, respectively. The expected return on investment (50% equity) for cooperative members with the spring lambing scenario, assuming a 50-acre leafy spurge infestation in a 100-acre pasture and new fence, was 16 percent (stocking rate of 1 ewe and lambs per acre of leafy spurge). While these returns are not a guarantee of success for the spring lambing alternative, they do provide an indication of the potential that such a cooperative may have.Leafy Spurge, Cooperative, Weed Control, Sheep Grazing, Economics, Farm Management, Resource /Energy Economics and Policy, Agribusiness,

Voltage- and Temperature-Dependent Allosteric Modulation of α7 Nicotinic Receptors by PNU120596

This is the final version of the article. Available from Frontiers Media via the DOI in this record.Alpha7 nicotinic acetylcholine receptors (α7 nAChR) are widely distributed throughout the central nervous system and are found at particularly high levels in the hippocampus and cortex. Several lines of evidence indicate that pharmacological enhancement of α7 nAChRs function could be a potential therapeutic route to alleviate disease-related cognitive deficits. A recent pharmacological approach adopted to increase α7 nAChR activity has been to identify selective positive allosteric modulators (PAMs). α7 nAChR PAMs have been divided into two classes: type I PAMs increase agonist potency with only subtle effects on kinetics, whereas type II agents produce additional dramatic effects on desensitization and deactivation kinetics. Here we report novel observations concerning the pharmacology of the canonical type II PAM, PNU120596. Using patch clamp analysis of acetylcholine (ACh)-mediated currents through recombinant rat α7 nAChR we show that positive allosteric modulation measured in two different ways is greatly attenuated when the temperature is raised to near physiological levels. Furthermore, PNU120596 largely removes the strong inward rectification usually exhibited by α7 nAChR-mediated responses