Dynamic input demand functions and resource adjustment for US agriculture: state evidence

The paper presents an econometric model of dynamic agricultural input demand functions that include research based technical change and autoregressive disturbances and fits the model to annual data for a set of state aggregates pooled over 1950–1982. The methodological approach is one of developing a theoretical foundation for a dynamic input demand system and accepting state aggreage behavior as approximated by nonlinear adjustment costs and long-term profit maximization. Although other studies have largely ignored autocorrelation in dynamic input demand systems, the results show shorter adjustment lags with autocorrelation than without. Dynamic input demand own-price elasticities for the six input groups are inelastic, and the demand functions possess significant cross-price and research effects

Ectopic Expression of E2F1 Stimulates β-Cell Proliferation and Function

OBJECTIVE-Generating functional beta-cells by inducing their proliferation may provide new perspectives for cell therapy in diabetes. Transcription factor E2F1 controls G(1)- to S-phase transition during the cycling of many cell types and is required for pancreatic beta-cell growth and function. However, the consequences of overexpression of E2F1 in beta-cells are unknown. RESEARCH DESIGN AND METHODS-The effects of E2F1 overexpression on beta-cell proliferation and function were analyzed in isolated rat beta-cells and in transgenic mice. RESULTS-Adenovirus AdE2F1-mediated overexpression of E2F1 increased the proliferation of isolated primary rat beta-cells 20-fold but also enhanced beta-cell death. Coinfection with adenovirus Ad Akt expressing a constitutively active form of Akt (protein kinase B) suppressed beta-cell death to control levels. At 48 h after infection, the total beta-cell number and insulin content were, respectively, 46 and 79% higher in AdE2F1+AdAkt-infected cultures compared with untreated. Conditional overexpression of E2F1 in mice resulted in a twofold increase of beta-cell proliferation and a 70% increase of pancreatic insulin content, but did not increase beta-cell mass. Glucose-challenged insulin release was increased, and the mice showed protection against toxin-induced diabetes. CONCLUSIONS-Overexpression of E2F1, either in vitro or in vivo, can stimulate beta-cell proliferation activity. In vivo E2F1 expression significantly increases the insulin content and function of adult beta-cells, making it a strategic target for therapeutic manipulation of beta-cell function. Diabetes 59:1435-1444, 201

The Main Belt Comets and ice in the Solar System

We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies

Human lens epithelial layer in cortical cataract

Normal and cataractous human eye lenses were studied by morphology and protein analysis. A marked decrease in protein sulfhydryl (PSH) and nonprotein sulfhydryl (NSPH) was observed in nuclear and cortical cataractous epithelia. Moreover, decrease in PSH contents and an increase in insoluble proteins were found to be correlated only in cortical cataractous epithelium which is also accompanied by various morphological abnormalities. In nuclear cataractous epithelium, however, there was very little insolubilisation of proteins. The epithelial morphology in nuclear cataracts was almost similar to normal lens epithelium. Hence, it is assumed that the protein insolubilisation and various morphological abnormalities are characteristics of cortical cataractous epithelium. This leads us to believe that opacification in cortical cataract might initiate in the epithelial layer

[Application de la théorie de la dualité en économie de la production agricole : utilisation pour la politique économique]

National audienceCet article de synthèse est divisé en deux parties. Dans une première partie, nous rappelons ce qu'est la théorie de la dualité en économie de la production et montrons comment elle peut être mise en œuvre sur la base de la fonction de profit. Nous montrons ensuite comment les caractéristiques de la technologie (relations de substitution-complémentarité, rendements d'échelle, progrès technique, séparabilité et jointure) peuvent être analysées. La deuxième partie de l'article est un bilan des applications de la théorie de la dualité aux agriculteurs des pays de la Communauté. Les apports et les limites de ces études empiriques sont soulignés dans une perspective d'utilisation à des fins d'analyse de politiques

[Application de la théorie de la dualité en économie de la production agricole : utilisation pour la politique économique]

National audienceCet article de synthèse est divisé en deux parties. Dans une première partie, nous rappelons ce qu'est la théorie de la dualité en économie de la production et montrons comment elle peut être mise en œuvre sur la base de la fonction de profit. Nous montrons ensuite comment les caractéristiques de la technologie (relations de substitution-complémentarité, rendements d'échelle, progrès technique, séparabilité et jointure) peuvent être analysées. La deuxième partie de l'article est un bilan des applications de la théorie de la dualité aux agriculteurs des pays de la Communauté. Les apports et les limites de ces études empiriques sont soulignés dans une perspective d'utilisation à des fins d'analyse de politiques

Acid phosphatase and lipid peroxidation in human cataractous lens epithelium

The anterior lens epithelial cells undergo a variety of degenerative and proliferative changes during cataract formation. Acid phosphatase is primarily responsible for tissue regeneration and tissue repair. The lipid hydroperoxides that are obtained by lipid peroxidation of polysaturated or unsaturated fatty acids bring about deterioration of biological membranes at cellular and tissue levels. Acid phosphatase and lipid peroxidation activities were studied on the lens epithelial cells of nuclear cataract, posterior subcapsular cataract, mature cataract, and mixed cataract. Of these, mature cataractous lens epithelium showed maximum activity for acid phosphatase (516.83 moles of p-nitrophenol released/g lens epithelium) and maximum levels of lipid peroxidation (86.29 O.D./min/g lens epithelium). In contrast, mixed cataractous lens epithelium showed minimum activity of acid phosphatase (222.61 moles of p-nitrophenol released/g lens epithelium) and minimum levels of lipid peroxidation (54.23 O.D./min/g lens epithelium). From our study, we correlated the maximum activity of acid phosphatase in mature cataractous lens epithelium with the increased areas of superimposed cells associated with the formation of mature cataract. Likewise, the maximum levels of lipid peroxidation in mature cataractous lens epithelium was correlated with increased permeability of the plasma membrane. Conversely, the minimum levels of lipid peroxidation in mixed cataractous lens epithelium makes us presume that factors other than lipid peroxidation may also account for the formation of mixed type of cataract