Frustration of freezing in a two dimensional hard-core fluid due to particle shape anisotropy

The freezing mechanism suggested for a fluid composed of hard disks [Huerta et al., Phys. Rev. E, 2006, 74, 061106] is used here to probe the fluid-to-solid transition in a hard-dumbbell fluid composed of overlapping hard disks with a variable length between disk centers. Analyzing the trends in the shape of second maximum of the radial distribution function of the planar hard-dumbbell fluid it has been found that the type of transition could be sensitive to the length of hard-dumbbell molecules. From the ${NpT}$ Monte Carlo simulations data we show that if a hard-dumbbell length does not exceed 15% of the disk diameter, the fluid-to-solid transition scenario follows the case of a hard-disk fluid, i.e., the isotropic hard-dumbbell fluid experiences freezing. However, for a hard-dumbbell length larger than 15% of disk diameter, there is evidence that fluid-to-solid transition may change to continuous transition, i.e., such an isotropic hard-dumbbell fluid will avoid freezing.Comment: 9 pages, 7 figure

Dynamic Price Relationships in the Grain and Cattle Markets, Pre and Post-Ethanol Mandate

This paper determines the dynamic interaction between prices of corn, soybean, grain sorghum (milo), wheat, feeder cattle and live (fed) cattle by taking into account the surge in corn consumption stemming from the boost of mandated ethanol production. Corn is a major carbohydrate-feed component of livestock, with grain sorghum and wheat serving as close substitutes. Moreover, soybean is an important protein-feed component. Being non-stationary data, a vector autoregressive (VAR) model (Sims, 1980) that includes an ‘error correction’ term is applied to the series; likewise known as a vector error correction (VEC) model (Engel and Granger, 1987 and Johansen, 1989). Two separate periods are estimated. The first considers prices prior to recent ethanol mandates. The second includes increased corn consumption from ethanol production, mandated by Energy Policy Acts of 2005 and 2007. Results are consistent with past literature regarding feeder and live cattle prices, among others. More importantly, we find support for the notion of modified feed rations in feedlot operations, given the increased corn prices following the post-ethanol mandated period. The finding is corroborated by two different methods, one via Granger Causality and other via impulse response functions.Corn Prices, Ethanol, Cattle Feed Price Dynamics, Agribusiness, Livestock Production/Industries, Risk and Uncertainty,

Price Volatility, Nonlinearity, and Asymmetric Adjustments in Corn, Soybean, and Cattle Markets: Implications of Ethanol-Driven (Market) Shocks

Grain prices have risen sharply since 2005 and 2006 affecting livestock markets by increasing feed prices and leading to significant volatility shocks. The high price levels and magnitude of sustained high volatilities has raised concerns for many sectors of the economy, in particular those with direct relation to these markets. Policy makers are analyzing the interrelationships among these markets, and the effects of energy market shocks on agricultural markets. This study considers a threshold structure in a multivariate time-series model that evaluates these market linkages, capturing asymmetric correlations between grain and livestock prices, including volatility spillovers. We empirically study the impact of corn usage for ethanol production in the evolution of the above mentioned prices. Results are compared to previous scenarios where corn, soybean and livestock production and consumption did not face the corn demand for ethanol production. We find positive dynamic correlations between corn and soybean and feeder and fed cattle prices, consistent with the literature. And we find an inverse or negative relation between corn and feeder/calf prices for the period post mandated ethanol production, as anticipated by the literature for increased corn prices. Also, we find there are adjustment costs inhibiting price transmission between the crops and the live cattle market, in the form of modifying feeding rations. More relevantly, we identify plausible asymmetric effect on the correlations between the markets, especially when considering the period for the ethanol driven corn consumption versus previous periods of corn consumption. These asymmetric correlations are the result of spillover effects.price volatility, market linkages, thresholds, ethanol-driven shocks, asymmetric correlations, spillovers, Agribusiness, Agricultural and Food Policy, Agricultural Finance, Demand and Price Analysis, Farm Management, Financial Economics, Public Economics, Research Methods/ Statistical Methods,

Multiproduct Optimal Hedging by Time-Varying Correlations in a State Dependent model of Regime-Switching

Replaced with revised version of paper 07/29/10.Agribusiness, Demand and Price Analysis, Risk and Uncertainty,

A State Dependent Regime Switching Model of Dynamic Correlations

Replaced with revised version of paper 07/29/09.dynamic correlations, regime switching, state dependent probabilities, thresholds, spillovers, Research Methods/ Statistical Methods,

Polarized 3 parton production in inclusive DIS at small x

Azimuthal angular correlations between produced hadrons/jets in high energy collisions are a sensitive probe of the dynamics of QCD at small x. Here we derive the triple differential cross section for inclusive production of 3 polarized partons in DIS at small x using the spinor helicity formalism. The target proton or nucleus is described using the Color Glass Condensate (CGC) formalism. The resulting expressions are used to study azimuthal angular correlations between produced partons in order to probe the gluon structure of the target hadron or nucleus. Our analytic expressions can also be used to calculate the real part of the Next to Leading Order (NLO) corrections to di-hadron production in DIS by integrating out one of the three final state partons.Comment: 5 pages, 6 figures; version accepted for publication in Physics Letters