On Painleve VI transcendents related to the Dirac operator on the hyperbolic disk

Dirac hamiltonian on the Poincare disk in the presence of an Aharonov-Bohm flux and a uniform magnetic field admits a one-parameter family of self-adjoint extensions. We determine the spectrum and calculate the resolvent for each element of this family. Explicit expressions for Green functions are then used to find Fredholm determinant representations for the tau function of the Dirac operator with two branch points on the Poincare disk. Isomonodromic deformation theory for the Dirac equation relates this tau function to a one-parameter class of solutions of the Painleve VI equation with $\gamma=0$. We analyze long distance behaviour of the tau function, as well as the asymptotics of the corresponding Painleve VI transcendents as $s\to 1$. Considering the limit of flat space, we also obtain a class of solutions of the Painleve V equation with $\beta=0$.Comment: 38 pages, 5 figure

POTENTIAL IMPLICATIONS OF FREER TRADE FOR THE UNITED STATES AND CANADIAN DAIRY SECTORS: A SPATIAL ANALYSIS

International Relations/Trade,

Non-equilibrium steady states in the Klein-Gordon theory

We construct non-equilibrium steady states in the Klein-Gordon theory in arbitrary space dimension $d$ following a local quench. We consider the approach where two independently thermalized semi-infinite systems, with temperatures $T_{\rm L}$ and $T_{\rm R}$, are connected along a $d-1$-dimensional hypersurface. A current-carrying steady state, described by thermally distributed modes with temperatures $T_{\rm L}$ and $T_{\rm R}$ for left and right-moving modes, respectively, emerges at late times. The non-equilibrium density matrix is the exponential of a non-local conserved charge. We obtain exact results for the average energy current and the complete distribution of energy current fluctuations. The latter shows that the long-time energy transfer can be described by a continuum of independent Poisson processes, for which we provide the exact weights. We further describe the full time evolution of local observables following the quench. Averages of generic local observables, including the stress-energy tensor, approach the steady state with a power-law in time, where the exponent depends on the initial conditions at the connection hypersurface. We describe boundary conditions and special operators for which the steady state is reached instantaneously on the connection hypersurface. A semiclassical analysis of freely propagating modes yields the average energy current at large distances and late times. We conclude by comparing and contrasting our findings with results for interacting theories and provide an estimate for the timescale governing the crossover to hydrodynamics. As a modification of our Klein-Gordon analysis we also include exact results for free Dirac fermions.Comment: 42 pages, 7 figure

From screen to summit: an investigation of claims about social media use for outdoor recreation purposes

Recent increases in visitation to public lands in the U.S. are often attributed to a rise in social media sharing of outdoor spaces, and particularly to the use of geotagging and hashtagging for location sharing. There are conflicting views on the influence of social media on visitation to public lands, including negative perceptions of social media users, and positive perceptions of social media’s potential to spread information to underrepresented and underserved communities. Due to the growing interest in social media use and its effects on outdoor spaces, it is important to understand how social media use correlates with recreational behavior compared to the rhetoric about this type of use. To this end, I conducted a discourse analysis of media articles on the subject, and implemented a visitor survey about recreation behavior, attitudes, and environmental identity at Jedediah Smith State Park, a park in Crescent City, California which is popular on social media. While discourse analysis found that opinions on social media use is largely two-sided for and against the technology, the survey results display a more complex and diverse relationship between social media use and outdoor recreation experience

Entanglement Content of Quantum Particle Excitations II. Disconnected Regions and Logarithmic Negativity

In this paper we study the increment of the entanglement entropy and of the (replica) logarithmic negativity in a zero-density excited state of a free massive bosonic theory, compared to the ground state. This extends the work of two previous publications by the same authors. We consider the case of two disconnected regions and find that the change in the entanglement entropy depends only on the combined size of the regions and is independent of their connectivity. We subsequently generalize this result to any number of disconnected regions. For the replica negativity we find that its increment is a polynomial with integer coefficients depending only on the sizes of the two regions. The logarithmic negativity turns out to have a more complicated functional structure than its replica version, typically involving roots of polynomials on the sizes of the regions. We obtain our results by two methods already employed in previous work: from a qubit picture and by computing four-point functions of branch point twist fields in finite volume. We test our results against numerical simulations on a harmonic chain and find excellent agreement

An Application of Experimental Economics to Agricultural Policies: the Case of U.S. Dairy Deregulation on Farm-Level Markets

R.B. 97-11Current dairy regulations in the U.S. are the result of over 80 years of regulatory activities. Through the 1920s and 1930s the U.S. government passed various acts designed to increase the share of market surplus captured by sellers, which at the time was judged insufficient. Lately, budget constraints and commitments to freer trade agreement have let the government and some dairy sector leaders contemplate different levels of dairy deregulation. The elimination of the Federal Milk Marketing Orders (FMMOs), a cornerstone of U.S. dairy regulation, has emerged as a possibility. The thought of eliminating the FMMOs was particularly disturbing to milk producers because of uncertainty regarding what might happen to the farm price, the volume of raw milk supplied, market stability and price efficiency, and to the distribution of market surplus between dairy farmers and dairy processing plants. These particular questions have not been extensively studied before due to data availability problems. Data from the era prior to the establishment of FMMOs would be difficult to obtain, and probably not meaningful because FMMOs have been around since the late-1930s. Experimental economics is used to simulate U.S. dairy market conditions and the effect of the elimination of FMMOs. The experimental task is a simple 2 X 2 matrix laboratory game. The treatments are oligopsony and regulation. Perishability is represented by an advance production decision with no carry-over and is kept constant across the experiments. Experimental sessions comprised 12 periods and a practice period. Sellers made production decisions and received a pool price, while buyers made a price (bid) and quantity decision. The allocation of units produced is made by the monitor on a highest bid basis. The game is computer assisted. Experimental results indicate that, in the absence of regulation, buyers are successful in reducing market price below the perfectly competitive price and in capturing a larger share of market surplus than a competitive solution predicts. Regulation reduced the market power of buyers and the price fluctuation of raw milk, in an oligopsonistic market, and had no significant impact on the overall price efficiency of the market

Investment behavior of Canadian Egg Producers: Analyzing the Impacts of Risk Aversion and Variability of Prices and Costs of Production

Animal welfare is a major concern for consumers. This concern has not gone unnoticed by sector stakeholders, especially egg producers. One of the fundamental changes likely to affect egg producers regards modes of production, specifically changes in housing systems, ranging from conventional cages to free range. From farmers’ perspective, changing their mode of production generates a technological and economic/marketing risk. This study documents the level of risk in the Canadian egg sector (conventional and specialty eggs) using data from 2009 to 2011. Our results indicate multiple uncertainty sources (technological, cost of production, price of eggs) that vary according to the types of eggs. We use a quadratic programming approach applied to expected mean-variance models to analyze the impact of risk on decision to invest when the resources must be allocated to different types of production that have different risk levels. Overall our results show how, given risk aversion parameters, producers minimize their risk levels by devoting their resources to the least risky type of eggs. An important result of our study is that supply management, by reducing the perceived risk level, has favored the development of specialty eggs, for the benefit of consumers

A Near-Infrared Survey of the Inner Galactic Plane for Wolf-Rayet Stars I. Methods and First Results: 41 New WR Stars

The discovery of new Wolf-Rayet (WR) stars in our Galaxy via large-scale narrowband optical surveys has been severely limited by dust extinction. Recent improvements in infrared technology have made narrowband-broadband imaging surveys viable again. We report a new J, K and narrow-band imaging survey of 300 square degrees of the plane of the Galaxy, spanning 150 degrees in Galactic longitude and reaching 1 degree above and below the Galactic plane. The survey has a useful limiting magnitude of K = 15 over most of the observed Galactic plane, and K = 14 within a few degrees of the Galactic center. Thousands of emission line candidates have been detected. In spectrographic follow-ups of 173 WR star candidates we have discovered 41 new WR stars, 15 of type WN and 26 of type WC. Star subtype assignments have been confirmed with K band spectra, and distances approximated using the method of spectroscopic parallax. A few of the new WR stars are amongst the most distant known in our Galaxy. The distribution of these new WR stars is seen to follow that of previously known WR stars along the spiral arms of the Galaxy. Tentative radial velocities were also measured for most of the new WR stars.Comment: 55 pages, 23 figures, 7 tables, accepted to Astronomical Journa

Non-Equilibrium Dynamics and Weakly Broken Integrability

Motivated by dynamical experiments on cold atomic gases, we develop a quantum kinetic approach to weakly perturbed integrable models out of equilibrium. Using the exact matrix elements of the underlying integrable model we establish an analytical approach to real-time dynamics. The method addresses a broad range of timescales, from the intermediate regime of pre-thermalization to late-time thermalization. Predictions are given for the time-evolution of physical quantities, including effective temperatures and thermalization rates. The approach provides conceptual links between perturbed quantum many-body dynamics and classical Kolmogorov-Arnold-Moser (KAM) theory. In particular, we identify a family of perturbations which do not cause thermalization in the weakly perturbed regime.Comment: v4: Improved discussion of perturbed Lieb-Liniger model and interactions. 5+10 pages, 3+7 figures. v3: New discussion of perturbed Lieb-Liniger model, mentioned in text and new section in SM. 5+10 pages, 3+7 figures. v2: references added and discussion of nearly-integrable perturbations improved. 5+9 pages, 3+5 figure