An Incentive System for Salmonella Control in the Pork Supply Chain

This paper presents a dynamic principal-agent analysis of an incentive system for Salmonella control in the pork supply chain. The incentive system determines quality premiums to the producer, testing frequencies for hogs delivered, as well as charges to the producer for testing and penalties. Using cost estimates and technical parameters, we evaluate the cost effectiveness of plant and farm control measures and trade-offs between prevalence reduction and related costs and gains. We also assess the impact of ownership structure on incentive system parameters and performance for a wide range of prevalence threshold levels. Differences in control actions, bacteriological prevalence and the overall welfare gain for the chain are very small across ownership structures. Changes in the prevalence threshold level lead to substantial changes in the use of farm and plant control packages and performance measures.dynamic programming, food quality, principal-agent, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,

Quadruple Yukawa Unification in the Minimal Supersymmetric Model

Predictions for m_t, tan beta, m_nu_tau are calculated for quadruple third family t-b-tau-nu_tau Yukawa unified models in the MSSM. The renormalisation group equations for the 3 families of the MSSM, including the right handed neutrino, are presented. For right handed tau neutrino Majorana masses that are bigger than 10^11 GeV, the tau neutrino mass is consistent with present cosmological bounds. The m_t, tan beta predictions are approximately equivalent to those in triple third family Yukawa unified models.Comment: 10 pages plain LaTex, uuencoded .epsf files in part 2. Revised version has NO changes to content, merely changed format to .tex fil

Effect of subsurface and surface tillage on structure and permeability of Solonetzic and Chernozemic soils over two years

Non-Peer ReviewedExcessive compaction in wet Chernozemic soils induced by field traffic may adversely alter soil structure, inhibit soil aeration, restrict water infiltration and nutrient uptake, and inhibit plant root development, affecting plant yields. Subsoiling at depth may be a solution to improve soil physical conditions in compacted Chernozemic and naturally dense Solonetzic (sodium affected) subsoils. On the other hand, vertical tillage implements may be used to manage residue and alter soil physical conditions mainly at the soil surface. The objective of this study was to evaluate the effect of subsurface and surface tillage on soil physical properties and plant yield in wheel traffic compacted and non-compacted Chernozemic and Solonetzic soils in southern Saskatchewan. Subsoiling increased air permeability. In the Chernozemic soil, the subsoiling treatments increased air permeability to 2.9x10-6 m sec-1 from 4.5x10-7 m sec-1. I n the Solonetzic soil, subsoiling decreased soil strength to 1579 KPa compared to 2376 KPa in the non-subsoiled treatment. Vertical tillage in the Chernozemic soil tended to decrease water infiltration and air permeability compared to the un-tilled soil which may be explained by an increase in the number of fine pores. Crop yields (wheat, canola, and peas) were not significantly affected by tillage except for sub-soiling of the compacted Solonetzic soil, which resulted in a seed yield increase of canola of ~ 1000 kg ha-1. Wheat and peas yields were not significantly affected by vertical tillage treatment. Overall, subsoiling of the compacted soils tended to have a greater influence on soil physical properties than vertical tillage

Bottom-Tau Yukawa Unification in the Next-to-Minimal Supersymmetric Standard Model

We discuss the unification of the bottom quark and tau lepton Yukawa couplings within the framework of the next-to-minimal supersymmetric standard model. We compare the allowed regions of the $m_t$-$\tan \beta$ plane to those in the minimal supersymmetric standard model, and find that over much of the parameter space the deviation between the predictions of two models is small, and nearly always much less than the effect of current theoretical and experimental uncertainties in the bottom quark mass and the strong coupling constant. However over some regions of parameter space top-bottom Yukawa unification cannot be achieved. We also discuss the scaling of the light fermion masses and mixing angles, and show that to within current uncertainties the results of recent texture analyses performed for the minimal model also apply to the next-to-minimal model.Comment: Southampton preprint SHEP 93/94-15, This is a latex file with postscript figures attached to the end of the documen

A Dark Matter Candidate from an Extra (Non-Universal) Dimension

We show that a recently constructed five-dimensional (5D) model with gauge-Higgs unification and explicit Lorentz symmetry breaking in the bulk, provides a natural dark matter candidate. This is the lightest Kaluza-Klein particle odd under a certain discrete Z_2 symmetry, which has been introduced to improve the naturalness of the model, and resembles KK-parity but is less constraining. The dark matter candidate is the first KK mode of a 5D gauge field and electroweak bounds force its mass above the TeV scale. Its pair annihilation rate is too small to guarantee the correct relic abundance; however coannihilations with colored particles greatly enhance the effective annihilation rate, leading to realistic relic densities.Comment: 26 pages, 10 figures; v2: fig.1 corrected, one reference and some comments added, conclusions unchanged. Version to appear in JHE

Generation of arbitrary two dimensional motional state of a trapped ion

We present a scheme to generate an arbitrary two-dimensional quantum state of motion of a trapped ion. This proposal is based on a sequence of laser pulses, which are tuned appropriately to control transitions on the sidebands of two modes of vibration. Not more than $(M+1)(N+1)$ laser pulses are needed to generate a pure state with upper phonon number $M$ and $N$ in the $x$ and $y$ direction respectively.Comment: to appear in PR

Wedgebox analysis of four-lepton events from neutralino pair production at the LHC

`Wedgebox' plots constructed by plotting the di-electron invariant mass versus the di-muon invariant mass from pp -> e^+e^- mu^+ mu^- + missing energy signature LHC events. Data sets of such events are obtained across the MSSM input parameter space in event-generator simulations, including cuts designed to remove SM backgrounds. Their study reveals several general features: (1)Regions in the MSSM input parameter space where a sufficient number of events are expected so as to be able to construct a clear wedgebox plot are delineated. (2)The presence of box shapes on a wedgebox plot either indicates the presence of heavy Higgs bosons decays or restricts the location to a quite small region of low \mu and M_2 values \lsim 200 GeV, a region denoted as the `lower island'. In this region, wedgebox plots can be quite complicated and change in pattern rather quickly as one moves around in the (\mu, M_2) plane. (3)Direct neutralino pair production from an intermediate Z^{0*} may only produce a wedge-shape since only \widetilde{\chi}_2^0\widetilde{\chi}_3^0 decays can contribute significantly. (4)A double-wedge or wedge-protruding-from-a-box pattern on a wedgebox plot, which results from combining a variety of MSSM production processes, yields three distinct observed endpoints, almost always attributable to \widetilde{\chi}_{2,3,4}^0 \to \widetilde{\chi}_1^0 \ell^+\ell^- decays, which can be utilized to determine a great deal of information about the neutralino and slepton mass spectra and related MSSM input parameters. Wedge and double-wedge patterns are seen in wedgebox plots in another region of higher \mu and M_2 values, denoted as the`upper island.' Here the pattern is simpler and more stable as one moves across the (\mu, M_2) input parameter space.Comment: 28 pages (LaTeX), 8 figures (encapsulated postscript

Flavour and Collider Interplay for SUSY at LHC7

The current 7 TeV run of the LHC experiment shall be able to probe gluino and squark masses up to values larger than 1 TeV. Assuming that hints for SUSY are found in the jets plus missing energy channel by the end of a 5 fb$^{-1}$ run, we explore the flavour constraints on three models with a CMSSM-like spectrum: the CMSSM itself, a Seesaw extension of the CMSSM, and Flavoured CMSSM. In particular, we focus on decays that might have been measured by the time the run is concluded, such as $B_s\to\mu\mu$ and $\mu\to e\gamma$. We also analyse constraints imposed by neutral meson bounds and electric dipole moments. The interplay between collider and flavour experiments is explored through the use of three benchmark scenarios, finding the flavour feedback useful in order to determine the model parameters and to test the consistency of the different models.Comment: 44 pages, 15 figures; v3: minor corrections, added references, updated figures. Version accepted for publicatio

Defining and characterizing team resilience in elite sport

Objectives: The objectives of this study were to develop a definition of team resilience and to identify the resilient characteristics of elite sport teams. Design and Method: Focus groups consisting of a total of 31 participants were conducted with five elite teams from a range of sports. An interpretive thematic analysis using inductive and deductive reasoning was employed to analyze the data. Results and Conclusions: Team resilience was defined as a dynamic, psychosocial process which protects a group of individuals from the potential negative effect of the stressors they collectively encounter. It comprises of processes whereby team members use their individual and combined resources to positively adapt when experiencing adversity. Findings revealed four main resilient characteristics of elite sport teams: group structure, mastery approaches, social capital, and collective efficacy. This study extends resilience research in sport psychology by providing greater conceptual clarity of resilience at a team level. The implications of the findings for those conducting research in this area and for those consulting with elite sport teams are discussed

Trace element geochemistry (Li, Ba, Sr, and Rb) using Curiosity's ChemCam: Early results for Gale crater from Bradbury Landing Site to Rocknest

The ChemCam instrument package on the Mars rover, Curiosity, provides new capabilities to probe the abundances of certain trace elements in the rocks and soils on Mars using the laser-induced breakdown spectroscopy technique. We focus on detecting and quantifying Li, Ba, Rb, and Sr in targets analyzed during the first 100 sols, from Bradbury Landing Site to Rocknest. Univariate peak area models and multivariate partial least squares models are presented. Li, detected for the first time directly on Mars, is generally low (100 ppm and >1000 ppm, respectively. These analysis locations tend to have high Si and alkali abundances, consistent with a feldspar composition. Together, these trace element observations provide possible evidence of magma differentiation and aqueous alteration. Key Points Quantitative models for Li, Ba, Rb and Sr using ChemCam data are presented Abundances for the first 100 sols in Gale crater are discussed These results represent the first in situ measurements of Li and Ba on Mar