Loop Equations and bootstrap methods in the lattice

Pure gauge theories can be formulated in terms of Wilson Loops correlators by means of the loop equation. In the large-N limit this equation closes in the expectation value of single loops. In particular, using the lattice as a regulator, it becomes a well defined equation for a discrete set of loops. In this paper we study different numerical approaches to solving this equation. Previous ideas gave good results in the strong coupling region. Here we propose an alternative method based on the observation that certain matrices $\hat{\rho}$ of Wilson loop expectation values are positive definite. They also have unit trace (\hat{\rho}\succeq 0, \mbox{tr} \hat{\rho}=1), in fact they can be defined as density matrices in the space of open loops after tracing over color indices and can be used to define an entropy associated with the loss of information due to such trace S_{WL}=-\mbox{tr}[ \hat{\rho}\ln \hat{\rho}]. The condition that such matrices are positive definite allows us to study the weak coupling region which is relevant for the continuum limit. In the exactly solvable case of two dimensions this approach gives very good results by considering just a few loops. In four dimensions it gives good results in the weak coupling region and therefore is complementary to the strong coupling expansion. We compare the results with standard Monte Carlo simulations.Comment: LaTeX, 46 pages, 17 figures. v2: References adde

The Impact of Cell Phones and BAC Laws on Motor Vehicle Fatality Rates

This paper develops a set of models for the determinants of automobile fatalities with particular attention devoted to the effects of increased cell phone usage. Cell phones have been associated with both life-taking and life-saving properties. However, prior statistical evaluations of the effects of cell phones have led to fragile results. We develop in this paper econometric models using time series data, allowing for polynomial structures of the regressors. The models are evaluated with a set of specification error tests providing reliable estimates of the effects of the various policy and driving related variables evaluated. The statistical results indicate the effect of cell phones is non-monotonic depending on the volume of phones in use, first having a net life-taking effect, then a net life-saving effect, followed finally with a net life-taking effect as the volume of phone use increases.Motor Vehicle Fatalities, Cell Phones, BAC Laws

A new effective exchange rate index for the dollar and its implications for U.S. merchandise trade

An introduction to a new exchange-rate index to measure the foreign-exchange value of the dollar. The authors develop a model of U.S. merchandise trade, featuring the new index.Foreign exchange rates ; Dollar, American

Particle tunneling through a polarizable insulator

The tunneling probability between two leads connected by a molecule, a chain, a film, or a bulk polarizable insulator is investigated within a model of an electron tunneling from lead A to a state higher in energy, describing the barrier, and from there to lead B. To describe the possibility of energy exchange with excitations of the molecule or the insulator we couple the intermediate state to a single oscillator or to a spectrum of these, respectively. In the single-oscillator case we find for weak coupling that the tunneling is weakly suppressed by a Debye-Waller-type factor. For stronger coupling the oscillator gets 'stiff' and we observe a suppression of tunneling since the effective barrier is increased. The probability for the electron to excite the oscillator increases with the coupling. In the case of a film, or a bulk barrier the behavior is qualitatively the same as in the single oscillator case. An insulating chain, as opposed to a film or a bulk connecting the two leads,shows an 'orthogonality catastrophe' similar to that of an electronic transition in a Fermi gas.Comment: 4 pages, 1 figur

Calving Difficulty in Beef Cattle: Part II

Many cattlemen believe reducing dietary energy during late pregnancy will decrease fetal size resulting in improved calving ease, whereas increasing energy will increase fetal size leading to a higher incidence of dystocia. Generally speaking, research has shown that lowering the energy allowance will decrease birth weight but will not significantly reduce dystocia. At MARC, Hereford and Angus 2-year-old heifers were fed three levels of energy (10.8, 13.7 or 17 .0 lb TDN/head/day) for 90 days prior to calving. Increasing the level of dietary energy resulted in increased birth weight but not increased dystocia; in fact, the incidence of calving difficulty was lower in the medium and high energy groups than in the low energy group

Calving Difficulty in Beef Cattle: Part I

Calving difficulty (dystocia) can increase calf losses, cow mortality, and veterinary and labor costs, as well as delay return to estrus, and lower conception rates. In two studies at the U.S. Meat Animal Research Center (MARC), Clay Center, Nebraska, calf losses within 24 hours of birth averaged 4 percent for those born with little or no assistance compared to 16 percent for those requiring assistance. Calf mortality increased by a 0.35 percent per pound increase in birth weight. In a Hereford herd at the U.S. Livestock and Range Research Station. Miles City, Montana, 57 percent of all calf losses were reported to be due to dystocia

Electric field effect on superconductivity at complex oxide interfaces

We examine the enhancement of the interfacial superconductivity between LaAlO$_{3}$ and SrTiO$_{3}$ by an effective electric field. Through the breaking of inversion symmetry at the interface, we show that a term coupling the superfluid density and an electric field can augment the superconductivity transition temperature. Microscopically, we show that an electric field can also produce changes in the carrier density by relating the measured capacitance to the density of states. Through the electron-phonon induced interaction in bulk SrTiO$_{3}$, we estimate the transition temperature.Comment: 7 Pages, Submitted to Physical Revie

Report from space plasma science

Space plasma science, especially plasma experiments in space, is discussed. Computational simulations, wave generation and propagation, wave-particle interactions, charged particle acceleration, particle-particle interactions, radiation transport in dense plasmas, macroscopic plasma flow, plasma-magnetic field interactions, plasma-surface interactions, prospects for near-term plasma science experiments in space and three-dimensional plasma experiments are among the topics discussed

Immunoregulatory Potential of Exosomes Derived from Cancer Stem Cells.

Head and neck squamous cell carcinomas (HNSCCs) are malignancies that originate in the mucosal lining of the upper aerodigestive tract. Despite advances in therapeutic interventions, survival rates among HNSCC patients have remained static for years. Cancer stem cells (CSCs) are tumor-initiating cells that are highly resistant to treatment, and are hypothesized to contribute to a significant fraction of tumor recurrences. Consequently, further investigations of how CSCs mediate recurrence may provide insights into novel druggable targets. A key element of recurrence involves the tumor's ability to evade immunosurveillance. Recent published reports suggest that CSCs possess immunosuppressive properties, however, the underlying mechanism have yet to be fully elucidated. To date, most groups have focused on the role of CSC-derived secretory proteins, such as cytokines and growth factors. Here, we review the established immunoregulatory role of exosomes derived from mixed tumor cell populations, and propose further study of CSC-derived exosomes may be warranted. Such studies may yield novel insights into new druggable targets, or lay the foundation for future exosome-based diagnostics

Experimental investigation of ultracold atom-molecule collisions

Ultracold collisions between Cs atoms and Cs2 dimers in the electronic ground state are observed in an optically trapped gas of atoms and molecules. The Cs2 molecules are formed in the triplet ground state by cw-photoassociation through the outer well of the 0g-(P3/2) excited electronic state. Inelastic atom-molecule collisions converting internal excitation into kinetic energy lead to a loss of Cs2 molecules from the dipole trap. Rate coefficients are determined for collisions involving Cs atoms in either the F=3 or F=4 hyperfine ground state and Cs2 molecules in either highly vibrationally excited states (v'=32-47) or in low vibrational states (v'=4-6) of the a ^3 Sigma_u^+ triplet ground state. The rate coefficients beta ~10^{-10} cm^3/s are found to be largely independent of the vibrational and rotational excitation indicating unitary limited cross sections.Comment: 4 pages, 3 figures, submitted for publicatio