bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bayesian Model Averaging in Consumer Demand Systems with Inequality Constraints
Authors: Chua C. L , Griffiths W. E. , O'Donnell C. J 
Published: July 2005

Share equations for the translog and almost ideal demand systems are estimated using Markov Chain Monte Carlo. A common prior on the elasticities and budget shares evaluated at average prices and income is used for both models. It includes equality restrictions (homogeneity, adding up and symmetry) and inequality restrictions (monotonicity and concavity). Posterior densities on the elasticities and shares are obtained; the problem of choosing between the results from the two alternative functional forms is resolved by using Bayesian model averaging. The application is to USDA data for beef, pork and poultry. Estimation of elasticities and shares, evaluated at mean prices and expenditure, is insensitive to model choice. At points away from the means, the estimates are sensitive, and model averaging has an impact.On estime les équations de partage des systèmes translog et de demande quasi idéale par la méthode de Monte Carlo en chaînes de Markov. Ces deux modèles reposent sur une prémisse commune, celle de l'évaluation des élasticités et des pans du budget à des prix et à des revenus moyens. Les analyses supposent certaines restrictions au niveau de l'égalité (homogénéité, addition et symétrie) et de l'inégalité (monotonie et concavité). On établit la densité des élasticités et des pans a posteriori. Le calcul de la moyenne par le modèle bayesien rend le choix entre les résultats de l'une ou l'autre fonction plus facile. L'auteur a appliqué cette méthode aux données de l'USDA sur le bœuf, le porc et la volaille. L'estimation des parts et des élasticités selon des dépenses et des prix moyens est insensible au modéle utilisé. Néanmoins, elle devient sensible quand on s'éloigne des valeurs moyennes, auquel cas, le modèle employé pour calculer la moyenne a une incidence sur les résultats.
Tobit Estimation with Unknown Point of Censoring with an Application to Milk Market Participation in the Ethiopian Highlands
Authors: Holloway Garth J. , Dorfman Jeffrey H. , Ehui Simeon K. 
Published: July 2005

Data augmentation is a powerful technique for estimating models with latent or missing data, but applications in agricultural economics have thus far been few. This paper showcases the technique in an application to data on milk market participation in the Ethiopian highlands. There, a key impediment to economic development is an apparently low rate of market participation. Consequently, economic interest centers on the “locations” of nonparticipants in relation to the market and their “reservation values” across covariates. These quantities are of policy interest because they provide measures of the additional inputs necessary in order for nonparticipants to enter the market. One quantity of primary interest is the minimum amount of surplus milk (the “minimum efficient scale of operations”) that the household must acquire before market participation becomes feasible. We estimate this quantity through routine application of data augmentation and Gibbs sampling applied to a random‐censored Tobit regression. Incorporating random censoring affects markedly the marketable‐surplus requirements of the household, but only slightly the covariates requirements estimates and, generally, leads to more plausible policy estimates than the estimates obtained from the zero‐censored formulation.Augmenter le nombre de données est une technique puissante permettant d'estimer les modèles pour lesquels les données manquent ou sont latentes, mais, jusqu'à présent, on n'y a guère recouru en économie rurale. L'article que void illustre une application de cette technique aux données se rapportant à la participation des producteurs au marché laitier dans les hauts plateaux de l'Éthiopie. Le faible taux de participation apparent constitue un obstacle de taille au développemenl économique de la région. Par conséquent, pour l'économiste, il est inléressanl de savoir où les « non‐participants » se trouvent par rapport au marché et de jauger leurs « réserves » en fonction des autres variables. Les valeurs de ce genre présenlenl de l'intérêt au niveau de l'élaboration des politiques, parce qu'elles donnent une idée des intrants supplémenlaires qui convaincraient les non‐participants de faire leur entrée sur le marché. Une valeur d'un intérêt primordial est le volume minimal de lait excédentaire («échelle minimale d'efficacité») que le ménage doit acquérir avant de participer au marché. On a eslimé cette valeur en appliquant la technique d'augmentation des données de la façon habituelle et en appliquant l'échanlillonnage de Gibbs à une régression Tobit censurée au hasard. L'intégration d'une censuration aléaloire affecte de maniére appréciable le volume de lait excédentaire commercialisable dont le ménage a besoin, mais ne louche que légèrement la valeur estimative des covariables requises et, en général, débouche sur des estimations plus plausibles que celles oblenues sans censuration en ce qui concerne l'élaboration des politiques.
Alternative Firm Strategies for Signaling Quality in the Food System
Authors: Sporleder Thomas L. , Goldsmith Peter D. 
Published: July 2005

Dynamics in the global food system, coupled with rapid advance in agricultural biotechnology, have resulted in additional demands for capturing information and sharing information vertically within the supply chain. Food safety and quality characteristics are a cornerstone of this information demand. Events such as foot‐and‐mouth disease (FMD) and bovine spongiform encephalopathy (BSE), genetic engineering and animal welfare concerns have laid the foundation for additional information need.Managers of private firms within the food supply chain must decide how to respond to the situation. A crucial component of the problem is what and how to provide information to downstream customers as well as stipulate what and how information is received from upstream suppliers. Alternative signaling mechanisms abound. The choice among these alternative signals, or combination of alternatives, has both short‐ and long‐run implications for the reputation of the firm, its products or services, and the efficiency with which it conducts its business. The signaling problem in the supply chain is bidirectional and has three critical dimensions: information asymmetry, incentive asymmetry, and arduous measurability. From a broad perspective, the choice set for signaling includes: strategies that rely on third‐party protocols and procedures; differentiation through branding and reputation; indemnification strategies such as insurance, warranties, and bonding; and coordination strategies such as strategic alliances and vertical integration (intemalization). Each mechanism for signaling differentially influences the three dimensions of the signaling problem. No globally optimal strategy solution exists. Differentiation through branding and reputation mitigate the signaling problem relatively well compared with the other alternatives.
The Economics of Controlling Infectious Diseases on Dairy Farms
Authors: Chi Junwook , Weersink Alfons , VanLeeuwen John A. , Keefe Gregory P. 
Published: July 2005

Cost‐effective disease control on the dairy farm can enhance productivity and subsequently profitability. Previous economic studies on animal disease have focused on production losses and evaluation of disease eradication programs and have provided little guidance on the optimal prevention action. This paper presents a theoretical model on the economics of livestock disease and develops an empirical model to determine the optimal set of control strategies for four production‐limiting cattle diseases: bovine viral diarrhea (BVD), enzootic bovine leukosis (EBL), Johne's Disease (JD) and neosporosis. Control functions indicating the prevalence of infection with each of the four diseases for each of the 10 strategies are estimated. The optimal strategies that minimize total disease cost (direct production losses and control expenditures) are provided for each disease on the basis of farm survey results from the maritime provinces. The results emphasize the importance of introduction checks before new animals enter the herd and adequate vaccination protection as cost‐effective control strategies.Lutter contre la maladie d'une manière rentable dans les élevages de bovins laitiers peut déboucher sur un meilleur rendement et des profits plus élevés. Les études économiques antérieures s'intéressant à cet aspect portaient essentiellement sur les pertes de production et l'évaluation des programmes d'éradication. Elles donnaient peu d'indications sur la solution idéale au niveau de la prévention. Cet article présente un modèle théorique de l'économique des maladies du bétail et aboutit à un modèle empirique permettant d'établir le jeu optimal de moyens pour lutter contre quatre maladies réduisant la production animale : la diarrhée à virus des bovins (DVB), la leucose bovine enzootique (LBE), la paratuberculose et la néosporose. Les auteurs estiment les fonctions qui indiquent la prévalence d'une infection pour chacune des quatre maladies retenues, dans le cadre des dix stratégies examinées. Ensuite, ils présentent les meilleures stratégies, à savoir celles qui minimisent le coût total de la maladie (pertes de production directes et dépenses associées à la lutte contre la maladie), pour chaque maladie en fonction des résultats d'un sondage auprès des éleveurs des provinces de l'Atlantique. Tout indique que les méthodes de lutte les plus rentables sont l'examen de l'animal avant son addition au troupeau et une vaccination qui protègera les bêtes de manière adéquate.
Termination of the WGTA: An Examination of Factor Market Distortions, Input Subsidies anc Compensation
Authors: Schmitz Troy G. , Highmoor Tim , Schmitz Andrew 
Published: July 2005

Input subsidies are common in North American agriculture and create production and trade distortions. As the theoretical discussion in this paper shows, the Crow transportation subsidy was no exception. The Crow benefit was eliminated in 1996 with the elimination of the Western Grain Transportation Act. Under the “pay the producer” approach, farmers in western Canada were compensated for the removal of the Crow subsidy, but the compensation was nowhere near that required to make grain and oilseed producers in western Canada at least as well off as before the Crow subsidy was removed. This policy change satisfied the compensation principle but not the Pareto principle. Reasons are given why this was the case, including very divergent views from various farm groups such as the National Farmers Union, the Alberta Cattle Commission, and the Alberta Barley Growers Association.Les intrants du secteur agricole sont souvent subventionnés en Amérique du Nord, ce qui fausse la production et les échanges. Comme l'illustre la discussion dans cet article, il en a été ainsi pour le tarif du Pas‐du‐Nid‐du‐Corbeau, dans les transports. Cette subvention a été abolie en 1996 avec l'abrogation de Loi sur le transport du grain de l'Ouest. Les producteurs de céréales et d'oléagineux de l'Ouest canadien ont été indemnisés, mais la somme qui leur a été versée était largement insuffisante pour qu'ils restent aussi bien lotis qu'avant l'abolition de la subvention. La nouvelle politique a satisfait le principe de la compensation, mais pas celui de Pareto. On explique le pourquoi de cette situation, l'une des raisons étant les points de vue tràs divergents de diverses associations agricoles.
Biotechnology Piracy: Rethinking the International Protection of Intellectual Property
Authors: Gaisford James D. , Tarvydas Robert , Hobbs Jill E. , Kerr William A. 
Published: July 2005

Access to international markets will be an important factor in investment decisions for firms engaging in the research and development of agricultural biotechnology. International market access can be restricted in two ways: the imposition of trade barriers and intellectual property piracy. This paper develops a model of the enforcement game between a developing country=s government and a foreign biotechnology firm to examine the efficacy of the World Trade Organization=s Agreement on Trade Related Aspects of Intellectual Property Rights (TRIPS) agreement for the protection of intellectual property in agricultural biotechnology. The conclusion is that the TRIPS is unlikely to provide sufficient protection and, thus, will lead to suboptimal levels of investment.L'accès aux marchés étrangers jouera un rôle capital dans les décisions des entreprises qui souhaitent investir dans la recherche et le développement en biotechnologie agricole. Deux éléments peuvent entraver l'accès au marché international: les barrières commerciales et le piratage de la propriété intellectuelle. Dans cet article, les auteurs modélisent les interactions entre le gouvernement d'un pays en développement et une entreprise de biotechnologie étrangère en vue d'établir dans quelle mesure l'Accord sur les ADPIC de l'OMC protège la propriété intellectuelle dans le secteur de la biotechnologie agricole. De cet exercice, ils concluent que la protection assurée par l'Accord sur les ADPIC est insuffisante, donc qu'on assistera à des investissements inférieurs aux investissements optimaux.
Pricing‐to‐Market: Simple Theoretical Insights, Formidable Econometric Challenges
Authors: Larue Bruno 
Published: July 2005

Pricing‐to‐market (PTM) arises when firms endowed with market power alter their pricing decisions in response to exchange rate changes. I argue that the empirical models commonly used in the literature are not properly specified, especially the ones pertaining to agri‐food trade. The nature of the relation between the export price and the exchange rate can be influenced by the time‐series properties of the data, by the choice of currency to be used for invoicing, by menu costs which posit that it is costly for firms to change prices, and by the production technology of the products traded. With menu costs, only large enough exchange rate changes can trigger systematic changes in export prices. The empirical implication is to test for threshold effects. Constant return to scale is analytically and empirically convenient, as it is a necessary assumption to support the typical single‐equation PTM specification. When goods are produced under increasing returns, there are also domestic PTM effects, and a system of equations is required to properly analyze the impacts of the exchange rate on pricing decisions at home and abroad. Jointness in production, so prevalent in the agri‐food sector, can support so‐called perverse PTM effects, even when firms maximize profits and there are no switching costs.Il y a tarification en fonction du marché (TFM) quand des entreprises exerçant une influence sur le marché modifient leurs prix d'après les fluctuations du cours du change. L'auteur soutient que les modèles empiriques couramment mentionés dans les textes ne sont pas assez bien spécifiés, en particulier ceux se rapportant au secteur agroalimentaire. La relation entre les prix d'exportation et la devise peut subir diverses influences, en l'occurrence celle des propriétés des données chronologiques, celle de la devise employée pour la facturation, celle des coûts d'ajustement, qui supposent que modifier les prix est une opération onéreuse pour l'entreprise, et celle des technologies de fabrication propres aux produits dont on fait le négoce. Avec les cou&#x030c;ts d'ajustement, seul un taux de change assez élevé enclenchera la modification systématique des prix d'exportation. L'implication empirique est qu'il faut vérifier les effets de seuil. Des rendements d'échelle constants s'avèrent commodes sur les plans analytique et empirique, et demeurent une hypothèse indispensable avec les spécifications typiques de la TFM à une équation. Quand le rendement s'accroît avec la production cependant, la TFM influe aussi sur le marché intérieur et l'on a besoin d'un jeu d'équations pour analyser correctement l'impact du taux de change sur les prix au pays et à l'étranger. Le regroupement des productions, si fréquent dans le secteur agroalimentaire, peut conforter les prétendus effets pervers de la TFM même quand les enterprises maximisent leurs bénéfices et le changement de fournisseur n'entraîne aucun frais.
Incidence and risk factors for liver enzyme elevation during highly active antiretroviral therapy in HIV-HCV co-infected patients: results from the Italian EPOKA-MASTER Cohort
Authors: Torti Carlo , Lapadula Giuseppe , Casari Salvatore , Puoti Massimo , Nelson Mark , Quiros-Roldan Eugenia , Bella Daniele , Pastore Giuseppe , Ladisa Nicoletta , Minoli Lorenzo , Sotgiu Giovanni , Mazzotta Francesco , Caputo Sergio Lo , Di Perri Giovanni , Filice Gaetano , Tinelli Carmine , Carosi Giampiero ,   the EPOKA-MASTER Study Group
Published: July 2005

Abstract

Background
The risk of hepatotoxicity associated with different highly active antiretroviral therapy (HAART) regimens (containing multiple-protease inhibitors, single-protease inhibitors or non nucleoside reverse transcriptase inhibitors) in HIV-HCV co-infected patients has not been fully assessed.

Methods
Retrospective analysis of a prospective cohort of 1,038 HIV-HCV co-infected patients who commenced a new HAART in the Italian MASTER database. Patients were stratified into naïve and experienced to antiretroviral therapy before starting the study regimens. Time to grade ≥III hepatotoxicity (as by ACTG classification) was the primary outcome. Secondary outcome was time to grade IV hepatotoxicity.

Results
Incidence of grade ≥III hepatotoxicity was 17.71 per 100 patient-years (p-yr) of follow up in naïve patient group and 8.22 per 100 p-yrs in experienced group (grade IV: 4.13 per 100 p-yrs and 1.08 per 100 p-yrs, respectively). In the latter group, the only independent factors associated with shorter time to the event at proportional hazards regression model were: previous liver transaminase elevations to grade ≥III, higher baseline alanine amino-transferase values, and use of a non nucleoside reverse transcriptase inhibitor based regimen. In the naive group, baseline aspartate transaminase level was associated with the primary outcome.

Conclusion
Use of a single or multiple protease inhibitor based regimen was not associated with risk of hepatotoxicity in either naïve or experienced patient groups to a statistically significant extent. A cautious approach with strict monitoring should be applied in HIV-HCV co-infected experienced patients with previous liver transaminase elevations, higher baseline alanine amino-transferase values and who receive regimens containing non nucleoside reverse transcriptase inhibitors.
Local versus systemic effect of ovulation-inducing factor in the seminal plasma of alpacas
Authors: Ratto Marcelo H , Huanca Wilfredo , Singh Jaswant , Adams Gregg P 
Published: July 2005

Abstract

Background
Camelids are induced (reflex) ovulators. We have recently documented the presence of an ovulation-inducing factor (OIF) in the seminal plasma of alpacas and llamas. The objective was to test the hypothesis that OIF exerts its effect via a systemic rather than a local route and that endometrial curettage will enhance the ovulatory response to intrauterine deposition of seminal plasma in alpacas.

Methods
Female alpacas were assigned randomly to 6 groups (n = 15 to 17 per group) in a 2 × 3 factorial design to test the effect of seminal plasma versus phosphate-buffered saline (PBS) given by intramuscular injection, by intrauterine infusion, or by intrauterine infusion after endometrial curettage. Specifically, alpacas in the respective groups were given 1) 2 ml of alpaca seminal plasma intramuscularly, 2) 2 ml of PBS intramuscularly (negative control group), 3) 2 ml of alpaca seminal plasma by intrauterine infusion, 4) 2 ml of PBS by intrauterine infusion (negative control group), 5) 2 ml of alpaca seminal plasma by intrauterine infusion after endometrial curettage, or 6) 2 ml of PBS by intrauterine infusion after endometrial curettage (negative control group). The alpacas were examined by transrectal ultrasonography to detect ovulation and measure follicular and luteal diameters.

Results
Intramuscular administration of seminal plasma resulted in a higher ovulation rate than intrauterine administration of seminal plasma (93% versus 41%; P < 0.01), while intrauterine seminal plasma after endometrial curettage was intermediate (67%). None of the saline-treated controls ovulated. The diameter of the CL after treatment-induced ovulation was not affected by the route of administration of seminal plasma.

Conclusion
We conclude that 1) OIF in seminal plasma effects ovulation via a systemic rather than a local route, 2) disruption of the endometrial mucosa by curettage facilitated the absorption of OIF and increased the ovulatory effect of seminal plasma, and 3) ovulation in alpacas is not associated with a physical stimulation of the genital tract, and 4) the alpaca represents an excellent biological model to evaluate the bioactivity of OIF.
Species differences in the effect of pregnancy on lymphocyte cytokine production between human and rat
Authors: Faas Marijke M , Bouman Annechien , Veenstra van Nieuwenhoven Angelique L , van der Schaaf Gerda , Moes Henk , Heineman Maas Jan , de Vos Paul 
Published: July 2005

AbstractIn the present study, we evaluated whether lymphocyte cytokine production during human and rat pregnancy shifts toward T helper cell type 2 (Th2) cytokine production. Therefore, blood samples were taken during the follicular and luteal phase and during pregnancy in rats and humans. Whole blood was ex vivo-stimulated with phorbol 12-myristate 13-acetate and calcium ionophore and intracellular interferon-γ (IFN-γ) and interleukin (IL)-4 production, and the percentage of cells in the various lymphocyte populations was measured using flow cytometry. Rats and humans adapted their immune responses to pregnancy but have different strategies: During human pregnancy, the percentage of lymphocytes producing IFN-γ was decreased, and the percentage IL-4-producing lymphocytes was not affected. The rat adapts its immune response to pregnancy by decreasing the total number of the various lymphocyte populations, and the percentage of IFN-γ- or IL-4-producing lymphocytes was not affected or increased (% IFN-γ-producing cytotoxic lymphocytes). It is speculated that during rat pregnancy, there is no need to decrease the number of IFN-γ-producing lymphocytes, as in nonpregnant rats, the total number of IFN-γ-producing lymphocytes after stimulation is relatively low, and there is no necessity for a further decrease. In nonpregnant humans, the percentage IFN-γ-producing lymphocytes is much higher and probably dangerous for pregnancy, and therefore, this percentage needs to decrease during pregnancy. In conclusion, although the data from humans concur with the Th1/Th2 paradigm, the data from rats do not concur with this paradigm. The present studies therefore challenge the classical Th1/Th2 paradigm during pregnancy.