U.S. livestock production and factor demand: a multiproduct dynamic dual approach

There is a need for modeling livestock production and factor use incorporating the interlinked dynamics of breeding herd adjustments in a theoretically consistent manner. Therefore, a multiple input-multiple output theoretical model is developed based on the adjustment cost hypothesis of production relationship involving sluggish adjustments of quasi-fixed inputs. Employing the results of intertemporal analogue of Hotelling\u27s lemma, a system of equations of optimal output supply, variable input demand, and quasi-fixed inputs (livestock breeding herds) investment is derived. Various issues like aggregation, expectation formation, and nonjointness in implementing this theoretical model are appraised.;A normalized quadratic value function is used to implement the proposed theoretical model. Beef, milk, pork, chicken, turkey, eggs, sheep and lambs, and wool (including mohair) are the eight outputs considered. The five variable inputs included in the empirical model are labor (numeraire), operating capital, grain feed, high protein feed, and hay. Various stocks of breeding herds like beef cows, dairy cows, sows, chicken layers, turkey breeder hens, and ewes (including Angora goats) are treated as appropriate nonallocatable quasi-fixed inputs. Stock of durable capital used in livestock production is also included in the list of quasi-fixed inputs studied. Sector-level aggregate data for the sample period 1950-1987 are used in the estimation. All parametric restrictions implied by the underlying theory of producer behavior (homogeneity, symmetry, and convexity) are maintained throughout the analysis.;The estimated model is subjected to a series of tests of hypotheses on the structure of dynamics of the livestock breeding herds. Nonjointness in production of some outputs is also tested. Results indicate the validity of the present approach in capturing the interlinkages that exist among the dynamics of these breeding herds. The nature and magnitude of such linkages are assessed by means of the coefficients of dynamic adjustments matrix. The important distinction of short run versus long run in responses for simulated external economic stimuli like changes in relative prices is accounted for in the elasticities calculation. In general, the reported elasticities compare favorably with similar estimates from other studies.;The present modeling effort does have few restrictive assumptions like static price expectation formation and a simple linear first order differential equation for approximating the dynamics of herd building. Nevertheless, it amply demonstrates that the theoretical requirements of economic modeling can be fully and meaningfully incorporated in practical applications for realistic results

An Application of the Computable General Equilibrium Model to Analyze U.S. Ariculture

The effects of exchange rate and capital stock changes are analyzed using a CGE model for the United States. The model is in the Walrasion tradition and is calibrated to 1982 data. Results indicate that a devaluation of the U.S. dollar has a positive effect on the agricultural sector and balance of trade, but has a negative effect on consumers

Synthesis of agarose-metal/semiconductor nanoparticles having superior bacteriocidal activity and their simple conversion to metal-carbon composites

Agarose, a naturally occurring biopolymer is used for the stabilization of metal, semiconductor nanoparticles. Ag and Cu nanoparticles stabilized in agarose matrix show excellent antibacterial activity against E. coli bacteria. The well dispersed metal nanoparticles within the agarose composite films can be readily converted to carbon-metal composites of catalytic importance

The Livestock Sector Submodel: A Description of Coefficient and Activity Development

The purpose of this paper is to provide an insight into the methodology used in calculating coefficients for the livestock sector of the Center for Agricultural and Rural Development\u27s (CARD) linear programming models. The livestock sector consists of four basic livestock activities—feeder cattle producing, feeder cattle finishing, dairy producing, and pork producing. These activities produce agricultural livestock commodities and nitrogen waste while requiring feed, water, energy, and capital. Four basic sources are used for the construction of the livestock sector—The Federal Enterprise Data System (FEDS), Nutrient Requirements for Beef Cattle, Dairy, and Swine published by the National Research Council, Utilizing Animal Waste as a Source of Nitrogen and Agricultural Resource Assessment System Technical Committee unpublished working papers

Water-solubilized aminoclay–metal nanoparticle composites and their novel properties

Nanoparticles of metals such as Au, Ag, Pd and Pt embedded in exfoliated sheets of aminoclays of the type R8Si8Mg6O16(OH)4, where R=CH2CH2NH2 are entirely water soluble. These sheets of the composite come to the organic-aqueous interface on addition of alkane thiols to the aqueous layer

An Analysis of the CAP Reform

The Treaty of Rome, which established the European Economic Community in 1957, defined the objectives of the Common Agricultural Policy (CAP). These objectives, contained in Article 39, follow: 1) Increase agricultural productivity by promoting technical progress and by ensuring rational development of agricultural production and optimum use of the production factors, particularly labor. 2) Ensure a fair standard of living for the agricultural community, in particular by increasing the individual earning of the persons engaged in agriculture. 3) Stabilize markets. 4) Assure the availability of supplies. 5) Ensure that supplies reach consumers at reasonable prices. The objectives of the CAP have been met, mostly through price policies that traditionally have been tied to production. The result of these policies is that production of many agricultural commodities has increased beyond levels necessary to meet CAP objectives and excess supplies have accumulated, been exported with subsidies, or both, at great expense to the European Community

Implications of a GATT Agreement for World Commodity Markets, 1993-98: An Analysis of the Dunkel Text on Agriculture

The Food and Agricultural Policy Research Institute (FAPRI) received a request in mid-February to analyze the proposed changes to agriculture and agricultural trade made by Arthur Dunkel. These changes essentially fall into three areas. 1) Export Competition. Subsidies are subject to reduction in two ways. Expenditures are to be reduced by 36 percent and quantities exported with the benefit of subsidies are to be reduced by 24 percent from 1986-90 average levels. 2) Internal Support. Using a world reference price based on the 1986-88 average levels, internal supports as measured by an aggregate measure of support (AMS) are to be reduced by 20 percent from 1986 levels. Credit will be given for support reductions made since 1986. 3) Market Access. Import restrictions are to be converted to tariffs and reduced across the board by a simple average of 36 percent. Tariffs on individual commodities are to be reduced by at least 15 percent. Where import barriers are in place, either minimum access of 3 percent of domestic consumption in 1993, rising to 5 percent in 1999, or minimum access of 1986-88 average import levels is to be provided, whichever is greater

Pulsed Feedback Defers Cellular Differentiation

Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable “polyphasic” positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a “timer” that operates over timescales much longer than a cell cycle

Role of the PAS sensor domains in the Bacillus subtilis sporulation kinase KinA

Histidine kinases are sophisticated molecular sensors that are used by bacteria to detect and respond to a multitude of environmental signals. KinA is the major histidine kinase required for initiation of sporulation upon nutrient deprivation in Bacillus subtilis. KinA has a large N-terminal region (residues 1 to 382) that is uniquely composed of three tandem Per-ARNT-Sim (PAS) domains that have been proposed to constitute a sensor module. To further enhance our understanding of this "sensor" region, we defined the boundaries that give rise to the minimal autonomously folded PAS domains and analyzed their homo- and heteroassociation properties using analytical ultracentrifugation, nuclear magnetic resonance (NMR) spectroscopy, and multiangle laser light scattering. We show that PAS(A) self-associates very weakly, while PAS(C) is primarily a monomer. In contrast, PAS(B) forms a stable dimer (K-d [dissociation constant] o

Long-term results of 32-mm alumina-on-alumina THA for avascular necrosis of the femoral head

BACKGROUND: Ceramic bearings in total hip arthroplasty (THA) have been introduced in clinical practice to minimize the problem of polyethylene particle-induced osteolysis. The aim of the study is to report the results of 68 consecutive alumina-on-alumina THAs done in 61 patients for avascular necrosis (AVN) of the femoral head. MATERIALS AND METHODS: In all implants a press-fit cup was used; it was combined with a 32-mm alumina head and with titanium-alloy stems. The mean age at surgery was 50 years. At an average follow-up of 13 years two hips have been revised, one for periprosthetic infection and one for excessive abduction of the cup. RESULTS: No revision for aseptic loosening is recorded; one anatomical cementless femoral stem had radiological evidence of definite aseptic loosening. No dislocations occurred, and no osteolysis was observed. CONCLUSIONS: The results support the application of alumina-alumina THA for long-lasting replacements