A 6-D Brane World Model

We consider a 6D space-time which is periodic in one of the extra dimensions and compact in the other. The periodic direction is defined by two 4-brane boundaries. Both static and non-static exact solutions, in which the internal spacetime has constant radius of curvature, are derived. In the case of static solutions, the brane tensions must be tuned as in the 5D Randall-Sundrum model, however, no additional fine-tuning is necessary between the brane tensions and the bulk cosmological constant. By further relaxing the sole fine-tuning of the model, we derive non-static solutions, describing de Sitter or Anti de Sitter 4D spacetimes, that allow for the fixing of the inter-brane distance and the accommodation of pairs of positive-negative and positive-positive tension branes. Finally, we consider the stability of the radion field in these configurations by employing small, time-dependent perturbations around the background solutions. In analogy with results drawn in 5 dimensions, the solutions describing a de Sitter 4D spacetime turn out to be unstable while those describing an Anti de Sitter geometry are shown to be stable.Comment: 22 pages, LaTeX file, no figure

Ixodes brunneus (Acari: Ixodidae) from Two Bird Hosts: A New Michigan Tick

The tick Ixodes brunneus Koch (Acari: Ixodidae) is reported for the first time in Michigan from two bird hosts at two locations in the lower peninsula. All stages of this tick exclusively feed on birds, and are primarily known from the southern U.S., although abundant records occur from northern states. The role of this species as a vector of pathogens is discussed

AN ALTERNATIVE APPROACH TO THE EVALUATION OF GOAL HIERARCHIES AMONG FARMERS

Results of a study of goal orderings of Saskatchewan farmers who participate in the province's FARMLAB Program are presented. We use the method of fuzzy pair-wise comparisons which allows the respondent to indicate a degree of preference between two alternative goal statements, thereby providing more information than in the binary case. From survey data ratio-scale scores are constructed for eight goal statements, and these are regressed on a set of farm enterprise and household characteristics and a psychological locus-of-control (or I-E) score. The empirical results indicate that goodness-of-fit measures are better than those obtained by other researchers, perhaps because a psychological measure (I-E score) is included as an explanatory variable for goal orderings.Farm Management,

Big Bang nucleosynthesis and the Quark-Hadron transition

An examination and brief review is made of the effects of quark-hadron transistion induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R is much greater the 10(exp 3), whereas the simplest models for the transition seem to restrict R to less than of approximately 10(exp 2)

Competing for a duopoly : international trade and tax competition

Oligopoly is empirically prevalent in the industries where MNEs operate and national governments compete with fiscal inducements for their FDI projects. Despite this, existing formal treatments of fiscal competition generally focus on the polar cases of perfect competition and monopoly. We consider the competition between two potential host governments to attract the investment of both firms in a duopolistic industry. Competition by identical countries for a monopoly firm's investment is known to result in a 'race to the bottom' where all rents are captured by the firm through subsidies. We demonstrate that with two firms, both are taxed in equilibrium, despite the explicit non-cooperation between governments. When countries differ in size, a single firm will be attracted to the larger market. We explore the conditions under which both firms in the duopoly co-locate and when each nation attracts a firm in equilibrium. Our results are consistent with the observed stability of effective corporate tax rates in the face of ongoing globalization, and our analysis readily generalizes to many specifications with oligopoly in the product markets

Metastable Charged Sparticles and the Cosmological Li7 Problem

We consider the effects of metastable charged sparticles on Big-Bang Nucleosynthesis (BBN), including bound-state reaction rates and chemical effects. We make a new analysis of the bound states of negatively-charged massive particles with the light nuclei most prominent in BBN, and present a new code to track their abundances, paying particular attention to that of Li7. Assuming, as an example, that the gravitino is the lightest supersymmetric particle (LSP), and that the lighter stau slepton, stau_1, is the metastable next-to-lightest sparticle within the constrained minimal supersymmetric extension of the Standard Model (CMSSM), we analyze the possible effects on the standard BBN abundances of stau_1 bound states and decays for representative values of the gravitino mass. Taking into account the constraint on the CMSSM parameter space imposed by the discovery of the Higgs boson at the LHC, we delineate regions in which the fit to the measured light-element abundances is as good as in standard BBN. We also identify regions of the CMSSM parameter space in which the bound state properties, chemistry and decays of metastable charged sparticles can solve the cosmological Li7 problem.Comment: 49 pages, 29 eps figure

Nuclear Reaction Uncertainties, Massive Gravitino Decays and the Cosmological Lithium Problem

We consider the effects of uncertainties in nuclear reaction rates on the cosmological constraints on the decays of unstable particles during or after Big-Bang nucleosynthesis (BBN). We identify the nuclear reactions due to non-thermal hadrons that are the most important in perturbing standard BBN, then quantify the uncertainties in these reactions and in the resulting light-element abundances. These results also indicate the key nuclear processes for which improved cross section data would allow different light-element abundances to be determined more accurately, thereby making possible more precise probes of BBN and evaluations of the cosmological constraints on unstable particles. Applying this analysis to models with unstable gravitinos decaying into neutralinos, we calculate the likelihood function for the light-element abundances measured currently, taking into account the current experimental errors in the determinations of the relevant nuclear reaction rates. We find a region of the gravitino mass and abundance in which the abundances of deuterium, He4 and Li7 may be fit with chi^2 = 5.5, compared with chi^2 = 31.7 if the effects of gravitino decays are unimportant. The best-fit solution is improved to chi^2 ~ 2.0 when the lithium abundance is taken from globular cluster data. Some such re-evaluation of the observed light-element abundances and/or nuclear reaction rates would be needed if this region of gravitino parameters is to provide a complete solution to the cosmological Li7 problem.Comment: 24 pages, 10 figure

Gravitino Decays and the Cosmological Lithium Problem in Light of the LHC Higgs and Supersymmetry Searches

We studied previously the impact on light-element abundances of gravitinos decaying during or after Big-Bang nucleosynthesis (BBN). We found regions of the gravitino mass m_{3/2} and abundance zeta_{3/2} plane where its decays could reconcile the calculated abundance of Li7 with observation without perturbing the other light-element abundances unacceptably. Here we revisit this issue in light of LHC measurements of the Higgs mass and constraints on supersymmetric model parameters, as well as updates in the astrophysical measurements of light-element abundances. In addition to the constrained minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking masses at the GUT scale (the CMSSM) studied previously, we also study models with universality imposed below the GUT scale and models with non-universal Higgs masses (NUHM1). We calculate the total likelihood function for the light-element abundances, taking into account the observational uncertainties. We find that gravitino decays provide a robust solution to the cosmological Li7 problem along strips in the (m_{3/2}, zeta_{3/2}) plane along which the abundances of deuterium, He4 and Li7 may be fit with chi^2_min < 3, compared with chi^2 ~ 34 if the effects of gravitino decays are unimportant. The minimum of the likelihood function is reduced to chi^2 < 2 when the uncertainty on D/H is relaxed and < 1 when the lithium abundance is taken from globular cluster data.Comment: 20 pages, 5 figures; added a new table and a discussion paragraph for it in Section 4, matches the published versio

Five-micron pictures of Jupiter

More than 440 five-micron "video" pictures of Jupiter with 1" resolution were made during 1973 September, October, and December. Comparisons of these pictures with color photographs show direct, detailed correlations with the darker "purple" features. Forty-four of these pictures were made just before Pioneer 10 encounter