Bayesian Analysis of a Japanese Meat Demand System: A Robust Likelihood Approach

This paper presents an application of Bayesian analysis to an AIDS model of Japanese meat demand extending previous approaches in three ways: (1) The methodology employed is robust with respect to the likelihood function but retains the generic, easily programmable character of algorithms offered by Monte Carlo Integration approaches based on the normal likelihood function. (2) In addition to inequality constraints, linear exact restrictions and stochastic prior information are subjected to a Bayesian posterior analysis of validity and incorporated into Bayesian point estimates of model parameters and elasticities. (3) In order to assess the influence of the prior density on posterior distributions of model parameters relative to the likelihood, a measure quantifying the "degree of prior influence" on the posterior is defined. Das Diskussionspapier stellt eine Bayes'sche Analyse eines AIDS Modells Japanischer Fleischnachfrage vor, die eine Erweiterung fruherer Ansatze in den folgenden drei Punkten darstellt:(1) Die verwendete Methode ist robust bezuglich der Likelihood Funktion, erhalt dabei aber die Flexibilitat und einfache Umsetzung von Algorithmen basierend auf Monte Carlo Integration und der Annahme der Normalverteilung. (2) Zusatzlich zu Ungleichheitsbedingungen werden exakte Restriktionen und stochastische a-priori Information einer Bayes'schen a-posteriori Analyse unterzogen und in die Bayes'sche Punktschatzung von Parametern und Elastizitaten einbezogen. (3) Ein Index zur Messung des Einflusses der a-priori Information auf die a-posteriori Verteilung der Modellparameter wird vorgestellt.Demand and Price Analysis,

Parity-violating DIS and the flavour dependence of the EMC effect

Isospin-dependent nuclear forces play a fundamental role in nuclear structure. In relativistic models of nuclear structure constructed at the quark level these isovector nuclear forces affect the u and d quarks differently, leading to non-trivial flavour dependent modifications of the nuclear parton distributions. We explore the effect of isospin dependent forces for parity-violating deep inelastic scattering on nuclear targets and demonstrate that the cross-sections for nuclei with N /= Z are sensitive to the flavour dependence of the EMC effect. Indeed, for nuclei like lead and gold we find that these flavour dependent effects are large.Comment: 4 pages, 2 figure

S-wave scattering of strangeness -3 baryons

We explore the interactions of two strangeness -3 baryons in multiple spin channels with lattice QCD. This system provides an ideal laboratory for exploring the interactions of multi-baryon systems with minimal dependence on light quark masses. Model calculations of the two-$\Omega^-$ system in two previous works have obtained conflicting results, which can be resolved by lattice QCD. The lattice calculations are performed using two different volumes with $L\sim2.5$ and 3.9 fm on anisotropic clover lattices at $m_\pi \sim 390$ MeV with a lattice spacing of $a_s \sim 0.123$ fm in the spatial direction and $a_t\sim{a}_s/3.5$ in the temporal direction. Using multiple interpolating operators from a non-displaced source, we present scattering information for two ground state $\Omega^-$ baryons in both the S=0 and S=2 channels. For S=0, $k\cot\delta$ is extracted at two volumes, which lead to an extrapolated scattering length of $a^{\Omega\Omega}_{S=0}=0.16 \pm 0.22 \ \text{fm}$, indicating a weakly repulsive interaction. Additionally, for S=2, two separate highly repulsive states are observed. We also present results on the interactions of the excited strangeness -3, spin-1/2 states with the ground spin-3/2 states for the spin-1 and spin-2 channels. Results for these interactions are consistent with attractive behavior.Comment: 21 pages, 10 fig

Spin-dependent structure functions in nuclear matter and the polarized EMC effect

An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu-Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks - hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions and find that we are readily able to reproduce both nuclear matter saturation and the experimental F^A_2N / F_2N ratio, that is, the EMC effect. Applying this framework to determine g^A_1p, we find that the ratio g^A_1p / g_1p differs significantly from 1, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which if confirmed experimentally, will reveal much about the quark structure of nuclear matter.Comment: 4 pages, 4 figure

A nonlinear Schr\"odinger equation for water waves on finite depth with constant vorticity

A nonlinear Schr\"odinger equation for the envelope of two dimensional surface water waves on finite depth with non zero constant vorticity is derived, and the influence of this constant vorticity on the well known stability properties of weakly nonlinear wave packets is studied. It is demonstrated that vorticity modifies significantly the modulational instability properties of weakly nonlinear plane waves, namely the growth rate and bandwidth. At third order we have shown the importance of the coupling between the mean flow induced by the modulation and the vorticity. Furthermore, it is shown that these plane wave solutions may be linearly stable to modulational instability for an opposite shear current independently of the dimensionless parameter kh, where k and h are the carrier wavenumber and depth respectively

Baryon Resonance Phenomenology

The Japan Hadron Facility will provide an unprecedented opportunity for the study of baryon resonance properties. This talk will focus on the chiral nonanalytic behaviour of magnetic moments exclusive to baryons with open decay channels. To illustrate the novel features associated with an open decay channel, we consider the ``Access'' quark model, where an analytic continuation of chiral perturbation theory is employed to connect results obtained using the constituent quark model in the limit of SU(3)-flavour symmetry to empirical determinations.Comment: 10 pages, 4 figures, ws-procs9x6.cls(included), Proceedings from the Joint CSSM/JHF Workshop, Adelaide, March 14-21, 200

Advection-Dominated Accretion with Infall and Outflows

We present self-similar solutions for advection-dominated accretion flows with radial viscous force in the presence of outflows from the accretion flow or infall. The axisymmetric flow is treated in variables integrated over polar sections and the effects of infall and outflows on the accretion flow are parametrised for possible configurations compatible with the self-similar solution. We investigate the resulting accretion flows for three different viscosity laws and derive upper limits on the viscosity parameter alpha. In addition, we find a natural connection to non-rotating and spherical accretion with turbulent viscosity, which is assumed to persist even without differential rotation. Positive Bernoulli numbers for advection-dominated accretion allow a fraction of the gas to be expelled in an outflow and the upper limit on the viscosity predicts that outflows are inevitable for equations of state close to an ideal gas.Comment: 17 pages, 9 figures, accepted for publication in the Astrophysical Journa

On the accurate long-time solution of the wave equation in exterior domains: Asymptotic expansions and corrected boundary conditions

We consider the solution of scattering problems for the wave equation using approximate boundary conditions at artificial boundaries. These conditions are explicitly viewed as approximations to an exact boundary condition satisfied by the solution on the unbounded domain. We study the short and long term behavior of the error. It is provided that, in two space dimensions, no local in time, constant coefficient boundary operator can lead to accurate results uniformly in time for the class of problems we consider. A variable coefficient operator is developed which attains better accuracy (uniformly in time) than is possible with constant coefficient approximations. The theory is illustrated by numerical examples. We also analyze the proposed boundary conditions using energy methods, leading to asymptotically correct error bounds