The Bayesian Score Statistic

We propose a novel Bayesian test under a (noninformative) Jeffreys’ prior specifica- tion. We check whether the fixed scalar value of the so-called Bayesian Score Statistic (BSS) under the null hypothesis is a plausible realization from its known and standard- ized distribution under the alternative. Unlike highest posterior density regions the BSS is invariant to reparameterizations. The BSS equals the posterior expectation of the classical score statistic and it provides an exact test procedure, whereas classical tests often rely on asymptotic results. Since the statistic is evaluated under the null hypothe- sis it provides the Bayesian counterpart of diagnostic checking. This result extends the similarity of classical sampling densities of maximum likelihood estimators and Bayesian posterior distributions based on Jeffreys’ priors, towards score statistics. We illustrate the BSS as a diagnostic to test for misspecification in linear and cointegration models

TI-games I: An Exploration of Type Indeterminacy In Strategic Decision-Making

The Type Indeterminacy model is a theoretical framework that formalizes the constructive preference perspective suggested by Kahneman and Tversky. In this paper we explore an extention of the TI-model from simple to strategic decision-making. A 2X2 game is investigated. We first show that in a one-shot simultaneaous move setting the TI-model is equivalent to a standard incomplete information model. We then let the game be preceded by a cheap-talk promise exchange game. We show in an example that in the TI-model the promise stage can have impact on next following behavior when the standard classical model predicts no impact whatsoever. The TI approach differs from other behavioral approaches in identifying the source of the effect of cheap-talk promises in the intrinsic indeterminacy of the players' type.Comment: 18

Study of Percolative Transitions with First-Order Characteristics in the Context of CMR Manganites

The unusual magneto-transport properties of manganites are widely believed to be caused by mixed-phase tendencies and concomitant percolative processes. However, dramatic deviations from "standard" percolation have been unveiled experimentally. Here, a semi-phenomenological description of Mn oxides is proposed based on coexisting clusters with smooth surfaces, as suggested by Monte Carlo simulations of realistic models for manganites, also briefly discussed here. The present approach produces fairly abrupt percolative transitions and even first-order discontinuities, in agreement with experiments. These transitions may describe the percolation that occurs after magnetic fields align the randomly oriented ferromagnetic clusters believed to exist above the Curie temperature in Mn oxides. In this respect, part of the manganite phenomenology could belong to a new class of percolative processes triggered by phase competition and correlations.Comment: 4 pages, 4 eps figure

f0(980) meson as a K bar K molecule in a phenomenological Lagrangian approach

We discuss a possible interpretation of the f0(980) meson as a hadronic molecule - a bound state of K and bar K mesons. Using a phenomenological Lagrangian approach we calculate the strong f0(980) to pi pi and electromagnetic f0(980) to gamma gamma decays. The compositeness condition provides a self-consistent method to determine the coupling constant between f0 and its constituents, K and bar K. Form factors governing the decays of the f0(980) are calculated by evaluating the kaon loop integrals. The predicted f0(980) to pi pi and f0(980) to gamma gamma decay widths are in good agreement with available data and results of other theoretical approaches.Comment: 21 pages, 11 figures, revised version accepted for publication in Eur. Phys. J.

Nucleation of a sodium droplet on C60

We investigate theoretically the progressive coating of C60 by several sodium atoms. Density functional calculations using a nonlocal functional are performed for NaC60 and Na2C60 in various configurations. These data are used to construct an empirical atomistic model in order to treat larger sizes in a statistical and dynamical context. Fluctuating charges are incorporated to account for charge transfer between sodium and carbon atoms. By performing systematic global optimization in the size range 1<=n<=30, we find that Na_nC60 is homogeneously coated at small sizes, and that a growing droplet is formed above n=>8. The separate effects of single ionization and thermalization are also considered, as well as the changes due to a strong external electric field. The present results are discussed in the light of various experimental data.Comment: 17 pages, 10 figure

Review of magnetic gear technologies and their applications in marine energy

The marine energy industry is in its early stages but has a large potential for growth. One of the most significant challenges is the reduction of operation and maintenance costs. Magnetic gears (MGs) offer the potential for long periods between maintenance intervals due to their frictionless torque transmission which could reduce these costs. This study presents a summary of the state of the art in MG technology and then investigates its potential for marine energy applications. A brief overview is given of the state of the marine energy industry and the environment in which marine energy converters (MECs) operate. A short history of MG development over the past century is then presented followed by a discussion of the leading MG technologies and their relative advantages. In order to demonstrate the potential of MGs in marine applications, the current technologies, i.e. mechanically geared and direct drive machines, are examined in terms of sizing, reliability and economic value using previous studies on a similar technology, namely wind. MGs are applied to four types of MECs to demonstrate how the technology can be incorporated. The potential to deploy at scale and potential obstacles to this are then discussed

Coherent QCD phenomena in the Coherent Pion-Nucleon and Pion-Nucleus Production of Two Jets at High Relative Momenta

We use QCD to compute the cross section for coherent production of a di-jet (treated as a $q\bar q$ moving at high relative transverse momentum,$\kappa_t$). In the target rest frame,the space-time evolution of this reaction is dominated by the process in which the high $\kappa_t$ $q\bar q$ component of the pion wave function is formed before reaching the target. It then interacts through two gluon exchange. In the approximation of keeping the leading order in powers of $\alpha_s$ and all orders in $\alpha_{s}\ln(\kappa_{t}^2/k_{0}^2),$ the amplitudes for other processes are shown to be smaller at least by a power of $\alpha_{s}$. The resulting dominant amplitude is proportional to $z(1-z) \kappa_t^{-4}$ ($z$ is the fraction light-cone(+)momentum carried by the quark in the final state) times the skewed gluon distribution of the target. For the pion scattering by a nuclear target, this means that at fixed $x_{N}= 2\kappa_{t}^2/s$ (but $\kappa_{t}^2\to \infty$) the nuclear process in which there is only a single interaction is the most important one to contribute to the reaction. Thus in this limit color transparency phenomena should occur.These findings are in accord with E971 experiment at FNAL. We also re-examine a potentially important nuclear multiple scattering correction which is positive and $\propto A^{1/3}/\kappa_t^4$. The meaning of the signal obtained from the experimental measurement of pion diffraction into two jets is also critically examined and significant corrections are identified.We show also that for values of $\kappa_t$ achieved at fixed target energies, di-jet production by the e.m. field of the nucleus leads to an insignificant correction which gets more important as $\kappa_t$ increases.Comment: 23 pages, 9 figure

Nonlinear cotunneling through an artificial molecule

We study electron transport through a system of two lateral quantum dots coupled in series. We consider the case of weak coupling to the leads and a bias point in the Coulomb blockade. After a generalized Schrieffer-Wolf transformation, cotunneling through this system is described using methods from lowest-order perturbation theory. We study the system for arbitrary bias voltages below the Coulomb energy. We observe a rich, non-monotonic behavior of the stationary current depending on the internal degrees of freedom. In particular, it turns out that at fixed transport voltage, the current through the system is largest at weak-to-intermediate inter-dot coupling.Comment: 4 pages, 5 figure