Management factors affecting the use of pasture by table chickens in extensive production systems

Whether chickens will make proper use of pasture is a problem experienced by producers of free-range and organic chickens. The aims of this project are to identify husbandry techniques and aspects of system design that encourage good pasture use. Two studies have been conducted comprising a winter and a summer flock. The aim of the winter flock was to examine the effect of outdoor artificial shelter on pasture usage. This was done for female Ross 308 birds grown to day 56, and ISA 657 birds grown to day 81. In summer, ISA 657 birds were grown to day 81. Treatments were either standard or enriched brooding, with pasture only or enriched pasture. Standard brooding was in a controlled environment house until day 42. Enriched brooding was in naturally ventilated houses in which birds had sight of pasture from an early age and access from day 21. Enriched pasture included artificial shelter, with straw bales and a conifer “wigwam” used to provide natural shelter. Chickens may be encouraged to go outdoors by brooding in a less “controlled” environment than that used for intensive broilers, and by allowing access to pasture when young. However, mortality was higher. Conifer wigwams may offer a means for more even use of pasture and better distribution of droppings

Applications of remote sensing to estuarine management

There are no author-identified significant results in this report

A study of the probability of depositing viable organisms on Mars during the Mariner 1964 mission

Probability of depositing viable organisms on Mars during 1964 Mariner missio

Transport in ultradilute solutions of 3^3He in superfluid 4^4He

We calculate the effect of a heat current on transporting $^3$He dissolved in superfluid $^4$He at ultralow concentration, as will be utilized in a proposed experimental search for the electric dipole moment of the neutron (nEDM). In this experiment, a phonon wind will generated to drive (partly depolarized) $^3$He down a long pipe. In the regime of $^3$He concentrations $\tilde < 10^{-9}$ and temperatures $\sim 0.5$ K, the phonons comprising the heat current are kept in a flowing local equilibrium by small angle phonon-phonon scattering, while they transfer momentum to the walls via the $^4$He first viscosity. On the other hand, the phonon wind drives the $^3$He out of local equilibrium via phonon-$^3$He scattering. For temperatures below $0.5$ K, both the phonon and $^3$He mean free paths can reach the centimeter scale, and we calculate the effects on the transport coefficients. We derive the relevant transport coefficients, the phonon thermal conductivity and the $^3$He diffusion constants from the Boltzmann equation. We calculate the effect of scattering from the walls of the pipe and show that it may be characterized by the average distance from points inside the pipe to the walls. The temporal evolution of the spatial distribution of the $^3$He atoms is determined by the time dependent $^3$He diffusion equation, which describes the competition between advection by the phonon wind and $^3$He diffusion. As a consequence of the thermal diffusivity being small compared with the $^3$He diffusivity, the scale height of the final $^3$He distribution is much smaller than that of the temperature gradient. We present exact solutions of the time dependent temperature and $^3$He distributions in terms of a complete set of normal modes.Comment: NORDITA PREPRINT 2015-37, 9 pages, 6 figure

The Rybczynski Theorem, Factor-Price Equalization, and Immigration: Evidence from U.S. States

Recent literature on the labor-market effects of U.S. immigration tends to find little correlation between regional immigrant inflows and changes in relative regional wages. In this paper we examine whether immigration, or endowment shocks more generally, altered U.S. regional output mixes as predicted by the Rybczynski Theorem of Heckscher-Ohlin (HO) trade theory. This theorem describes how regions can absorb endowment shocks via changes in output mix without any changes in relative regional factor prices. Treating U.S. states as HO regions, we search for evidence of regional output-mix effects using a new data set that combines state endowments, outputs, and employment in 1980 and 1990. We have two main findings. First, state output-mix changes broadly match state endowment changes. Second, variation in state unit factor requirements is consistent with relative factor-price equalization (FPE) across states, which is a sufficient condition for our output-mix hypothesis to hold. Overall, these findings suggest that states absorb regional endowment shocks through mechanisms other than changes in relative regional factor prices.

Transport in very dilute solutions of 3^3He in superfluid 4^4 He

Motivated by a proposed experimental search for the electric dipole moment of the neutron (nEDM) utilizing neutron-$^3$He capture in a dilute solution of $^3$He in superfluid $^4$He, we derive the transport properties of dilute solutions in the regime where the $^3$He are classically distributed and rapid $^3$He-$^3$He scatterings keep the $^3$He in equilibrium. Our microscopic framework takes into account phonon-phonon, phonon-$^3$He, and $^3$He-$^3$He scatterings. We then apply these calculations to measurements by Rosenbaum et al. [J.Low Temp.Phys. {\bf 16}, 131 (1974)] and by Lamoreaux et al. [Europhys.Lett. {\bf 58}, 718 (2002)] of dilute solutions in the presence of a heat flow. We find satisfactory agreement of theory with the data, serving to confirm our understanding of the microscopics of the helium in the future nEDM experiment.Comment: 10 pages, 5 figures, v

Low Temperature Transport Properties of Very Dilute Classical Solutions of 3^3He in Superfluid 4^4He

We report microscopic calculations of the thermal conductivity, diffusion constant and thermal diffusion constant for classical solutions of $^3$He in superfluid $^4$He at temperatures T \la 0.6~K, where phonons are the dominant excitations of the $^4$He. We focus on solutions with $^3$He concentrations \la \,10^{-3}, for which the main scattering mechanisms are phonon-phonon scattering via 3-phonon Landau and Beliaev processes, which maintain the phonons in a drifting equilibrium distribution, and the slower process of $^3$He-phonon scattering, which is crucial for determining the $^3$He distribution function in transport. We use the fact that the relative changes in the energy and momentum of a $^3$He atom in a collision with a phonon are small to derive a Fokker-Planck equation for the $^3$He distribution function, which we show has an analytical solution in terms of Sonine polynomials. We also calculate the corrections to the Fokker-Planck results for the transport coefficients.Comment: 29 pages, 2 figure

Applications of remote sensing to estuarine management

Remote sensing was used in the resolution of estuarine problems facing federal and Virginia governmental agencies. A prototype Elizabeth River Surface Circulation Atlas was produced from photogrammetry to aid in oil spill cleanup and source identification. Aerial photo analysis twice led to selection of alternative plans for dredging and spoil disposal which minimized marsh damage. Marsh loss due to a mud wave from a highway dyke was measured on sequential aerial photographs. An historical aerial photographic sequence gave basis to a potential Commonwealth of Virginia legal claim to accreting and migrating coastal islands

Immigration and African-American Employment Opportunities: The Response of Wages, Employment, and Incarceration to Labor Supply Shocks

The employment rate of black men, and particularly of low-skill black men, fell precipitously from 1960 to 2000. At the same time, the incarceration rate of black men rose markedly. This paper examines the relation between immigration and these trends in black employment and incarceration. Using data drawn from the 1960-2000 U.S. Censuses, we find a strong correlation between immigration, black wages, black employment rates, and black incarceration rates. As immigrants disproportionately increased the supply of workers in a particular skill group, the wage of black workers in that group fell, the employment rate declined, and the incarceration rate rose. Our analysis suggests that a 10-percent immigrant-induced increase in the supply of a particular skill group reduced the black wage by 4.0 percent, lowered the employment rate of black men by 3.5 percentage points, and increased the incarceration rate of blacks by almost a full percentage point.

Solution of a statistical mechanics model for pulse formation in lasers

We present a rigorous statistical-mechanics theory of nonlinear many mode laser systems. An important example is the passively mode-locked laser that promotes pulse operation when a saturable absorber is placed in the cavity. It was shown by Gordon and Fischer [1] that pulse formation is a first-order phase transition of spontaneous ordering of modes in an effective "thermodynamic" system, in which intracavity noise level is the effective temperature. In this paper we present a rigorous solution of a model of passive mode locking. We show that the thermodynamics depends on a single parameter, and calculate exactly the mode-locking point. We find the phase diagram and calculate statistical quantities, including the dependence of the intracavity power on the gain saturation function, and finite size corrections near the transition point. We show that the thermodynamics is independent of the gain saturation mechanism and that it is correctly reproduced by a mean field calculation. The outcome is a new solvable statistical mechanics system with an unstable self-interaction accompanied by a natural global power constraint, and an exact description of an important many mode laser system.Comment: 10 pages, 3 figures, RevTe