17,258 research outputs found
INDUSTRY EXPERIENCE: LIVESTOCK ECONOMIST
Livestock Production/Industries,
Impact of the Ethanol Boom on Livestock and Dairy Industries: What Are They Going to Eat?
Increased demand for corn for ethanol production has helped push grain prices to record levels. This has increased livestock production costs, and producers have responded with changes to production systems. This paper explores the degree to which costs can be mitigated with alternative feeds, the effect this might have on physical performance, and the impact of alternative feeds on the competitive position of different species.cattle feeding, corn, cost of production, ethanol, Agribusiness, Farm Management, Livestock Production/Industries, Production Economics, Research and Development/Tech Change/Emerging Technologies, Q12, Q13,
Phosphorus and arsenic distributions in a seasonally-stratified, iron- and manganese-rich lake: microbiological and geochemical controls
Seasonal stratification in temperate lakes greater than a few metres deep provides conditions amenable to pronounced vertical zonation of redox chemistry. Such changes are particularly evident in eutrophic systems where high phytoplankton biomass often leads to seasonally-established anoxic hypolimnia and profound changes in geochemical conditions. In this study, we investigated the behaviour of trace elements in the water column of a seasonally-stratified, eutrophic lake. Two consecutive years of data from Lake Ngapouri, North Island, New Zealand, demonstrate the occurrence of highly correlated profiles of phosphorus (P), arsenic (As), iron (Fe) and manganese (Mn), all of which increased in concentration by 1-2 orders of magnitude within the anoxic hypolimnion. Stoichiometric and mass-balance considerations demonstrate that increases in alkalinity in hypolimnetic waters were consistent with observed changes in sulfate, Fe and Mn concentrations with depth, corresponding to dissimilatory reduction of sulfate, Fe(III) and Mn(IV) hydroxides. Thermodynamic constraints on Fe, Mn and Al solubility indicate that amorphous Fe(III), Mn(IV) hydroxides most probably controlled Fe and Mn in the surface mixed layer (~0 to 8 m) while Al(III) hydroxides were supersaturated throughout the entire system. Surface complexation modelling indicated that iron hydroxides (HFO) potentially dominated As speciation in the lake. It is likely that other colloidal phases such as allophanic clays also limited HPO42- activity, reducing competition for HAsO42- adsorption to iron hydroxides. This research highlights the coupling of P, As, Fe and Mn in Lake Ngapouri, and the apparent role of multiple colloidal phases in affecting P and As activity within overarching microbiological and geochemical processes
Thermodynamics of an incommensurate quantum crystal
We present a simple theory of the thermodynamics of an incommensurate quantum
solid. The ground state of the solid is assumed to be an incommensurate
crystal, with quantum zero-point vacancies and interstitials and thus a
non-integer number of atoms per unit cell. We show that the low temperature
variation of the net vacancy concentration should be as , and that the
first correction to the specific heat due to this varies as ; these are
quite consistent with experiments on solid He. We also make some
observations about the recent experimental reports of ``supersolidity'' in
solid He that motivate a renewed interest in quantum crystals.Comment: revised, new title, somewhat expande
Producing Bose condensates using optical lattices
We relate the entropies of ensembles of atoms in optical lattices to atoms in
simple traps. We then determine which ensembles of lattice-bound atoms will
adiabatically transform into a Bose condensate. This shows a feasible approach
to Bose condensation without evaporative cooling.Comment: RevTeX, 5 pages, 5 eps-figure
Design Guidelines for Offset Journal Bearings in Two-Stroke Engines
Offset journal bearings are an attractive design option for cross-head and piston bearings for two-stroke engines. Two-stroke engine design has seen a resurgence in the last few years due to potential gains in engine efficiency over their four-stroke counterparts. The cross-head and piston bearings comprising such engines, however, are characterized by non-reversing loads with limited oscillating journal motion, the combination of which provides poor bearing performance for conventional cylindrical bearings. The division of bearing journal and sleeve into offset segments allows for periodic load relaxation in the segments and development of squeeze-film action which substantially improves bearing performance. Offset bearings have been in production for the past 60 years, but there are no general design guidelines available to the engine analyst. This thesis provides predictions of the primary bearing performance factors, cyclic-minimum film thickness and cyclic-maximum film pressure, over a wide range of design parameters found in production-level, two-stroke engines
Disruption in the Supply Chain for Beef and Pork: What Has Happened and What Was NAFTA Doing
Industrial Organization, International Relations/Trade,
The Impact of the National Counter-Cyclical Income Support Program for Dairy Producers on Representative Dairy Farms
This report contains the results of an analysis of the National Counter-Cyclical Income Support Program for Dairy Producers on the Agricultural and Food Policy Center’s (AFPC) representative dairy farms. The impact of the proposal on the representative farms is evaluated in terms of the change in average annual cash receipts and the change in the average annual net cash farm income. The role and potential importance of payment limits on these farms are discussed. All milk prices by state and program benefits under the payment limit binding and nonbinding scenarios were developed by FAPRI and were applied to the representative dairies. For more information on those results see the FAPRI analysis of this program.Agribusiness, Agricultural and Food Policy, Livestock Production/Industries,
Can We Save the Traditional Family Farm?
What is a traditional family farm? Is it a family of four living on a farm and supplying all of the labor, capital and management or is it a family corporation with four families supplying all of the capital and management? These types of questions continue to arise in policy debates, as they have for many years. While subject to heated debate and the core of many people’s positions on farm programs the answer is more sociological as it is becoming less and less economically relevant. Whether these types of farms or any other farm sizes should survive is not a question that can be answered by a policy analyst. The job of an analyst is to determine if and under what conditions family farms can survive. To this end, this paper reviews the various definitions of family farms and draws inferences as to the economic and financial survival of these different size farms using the results generated from simulating representative farms.Agricultural and Food Policy,
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