6,573 research outputs found

    FARM WORK, OFF-FARM WORK, AND HIRED FARM LABOR: ESTIMATING A DISCRETE-CHOICE MODEL OF FRENCH FARM COUPLES' LABOR DECISIONS

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    We estimate jointly three types of discrete-choice labor decisions of farm couples: farm work, off-farm work, and hired farm labor. Using a 16-choice multinomial logit model, we find that operators' and spouses' farm labor are substitutes. Hired farm labor increases with farmers' qualifications, perhaps substituting for the couples' labor inputs. Other adults in the households substitute for the farm labor input of the farm couple and hired workers.Labor and Human Capital,

    Measuring Competition between Non-Food and Food Demand on World Grain Markets : Is Biofuel Production Compatible with Pressure for Food Production ?

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    The flow of agricultural products between countries is conditioned by several factors including domestic and trade policy tools for the main competing exporters countries, and macroeconomic variables (such as real income per capita, rate of population growth,etc). Important structural changes are occurring on world agricultural markets that will have an impact on the long term competitiveness of countries and regions. These changes include developments in biofuels production linked to policy incentives, and the rapid growth in income and population numbers in some developing countries (such as India and China). An important issue is to identify the factors that are going to modify the balance between the supply and demand for agricultural products in the long term. In this paper, we look the example of arable crops. These markets allow an interesting analysis since they are directly concerned with the evolution of biofuels. One important question is to measure the competition between food demand and non food demand. We use a partial equilibrium model that focuses on world arable crop markets, the World Econometric Modeling of Arable Crops. The aim of the model is to produce annual market projections over a medium-term perspective and to simulate the impact of alternative national and international agricultural policy reforms for the main arable crops. The results of the simulations performed show that even if incentives to produce of biofuels have strong impacts on world markets, other factors such as changes in the assumptions of concerning the growth of emerging countries are also of great importance since the world cereal and oilseed markets as much are just bymodeling, econometric, partial equilibrium, land uses, biofuels, Demand and Price Analysis, International Relations/Trade,

    Measuring the Effects of Alternative Support Policy Instruments on Beef Supply

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    The European Union beef market regulation is largely influenced by the Common Agricultural Policy (CAP). With the 1992 CAP reform, there was a partial shift by the EU from product price support to a more direct form of income support by way of direct payments. For beef there was a move to direct payments on intermediate products which was essentially a direct payment for the possession of various categories of animals and these were linked to a land resource base. The Agenda 2000 reform consists in a further price decrease associated with an increase in direct payments. The objective of this paper is to assess how the behaviour of beef producers is sensitive to changes in production prices and to changes in premiums. The analysis relies on an analytical framework which allows to take into account the dynamic feature of beef production and the subsidies provided by the Common Agricultural Policy. We studys how the beef supply response is modified when various exogenous variables like prices or premiums are changed. The application focuses on the dynamics of beef supply response in the French beef sector.beef supply, dynamic modelling, expectations, direct payments, Common Agricultural Policy, Agricultural and Food Policy, C61, Q12, Q18,

    Convergence to Equilibrium in the Free Fokker-Planck Equation With a Double-Well Potential

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    We consider the one-dimensional free Fokker-Planck equation ∂Ό_t∂t=∂∂x[ÎŒ_t(12Vâ€Č−HÎŒ_t)]\frac{\partial \mu\_t}{\partial t} = \frac{\partial}{\partial x} \left[ \mu\_t \left( \frac12 V' - H\mu\_t \right) \right], where HH denotes the Hilbert transform and VV is a particular double-well quartic potential, namely V(x)=14x4+c2x2V(x) = \frac14 x^4 + \frac{c}{2} x^2, with −2≀c<0-2 \le c < 0. We prove that the solution (ÎŒ_t)_t≄0(\mu\_t)\_{t \ge 0} of this PDE converges to the equilibrium measure ÎŒ_V\mu\_V as tt goes to infinity, which provides a first result of convergence in a non-convex setting. The proof involves free probability and complex analysis techniques

    WORLD CEREALS MARKETS UNDER ALTERNATIVE COMMON AGRICULTURAL POLICY REFORMS

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    Previous quantitative assessments of likely impacts of recent reforms of the Common Agricultural Policy (in particular the Agenda 2000) differ across empirical studies. Differences are mainly due to the ways the policy instruments are taken into account (explicit modeling or implicit modeling i.e. using ad-valorem equivalents). The aim of this paper is to assess empirically the impacts of recent reforms of the Common Agricultural Policy and the consequences of the Mid-Term proposals on world cereals markets. We develop an econometric, dynamic, multi-product, partial equilibrium commodity model that focuses on arable crops. Major exporters and major importers are modeled separately, other countries being included in a "rest of the world" category. For the countries or regions explicitly integrated the model estimates supply, demand and trade. The model we develop has two important features: i) the parameters estimated in the behavioral equations (supply and demand) satisfy regularity conditions and ii) the agricultural policy instruments (in particular CAP instruments) are modeled in an explicit way. In the empirical section, attention focuses on the world cereals market. We provide a market outlook through the year 2009 for three different scenarios: baseline projections and two scenarios based on different assumptions regarding the evolution of the Common Agricultural Policy (the Mid-Term Review scenario and the decoupling scenario). Estimated effects of the mid-term scenario on EU crop prices depend on the relationship between EU and world market prices.Agricultural and Food Policy,

    Characterising the impact of surface integrity on the fatigue behaviour of forged components

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    The present study focusses on analysing and modelling the influence on fatigue behaviour of the surface of a hot-forged C70 connecting rod which undergoes a shot-blasting treatment. The shot-blasting heavily affects the surface and thus the fatigue properties. In addition, the forging process introduces large defects which also have an effect on the fatigue strength. So as to be able to determine which aspects of the surface integrity are the most influential in fatigue, various surface states were thoroughly characterised and then tested in high cycle fatigue in bending. The various aspects studied are the surface roughness and large defects, residual stresses, microstructure and hardness

    Characterising the impact of surface integrity on the fatigue behaviour of a shot-peened connecting rod

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    The present study focuses on analysing and modelling the influence on fatigue behaviour of the surface of a hot-forged C70 connecting rod which undergoes a shot-blasting treatment. The shot-blasting heavily affects the surface and thus the fatigue properties. In addition, the forging process introduces large defects which also have an effect on the fatigue strength. So as to be able to determine which aspects of the surface integrity are the most influential in fatigue, additional surface states were generated by shot-peening the as-forged surface. The various surface states were thoroughly characterised and then tested in high cycle fatigue in bending. The various aspects studied are the surface roughness and large defects, residual stresses, and microstructure

    Sources Of Student Engagement In Introductory Physics For Life Sciences

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    We explore the sources of student engagement with curricular content in an Introductory Physics for Life Science (IPLS) course at Swarthmore College. Do IPLS students find some life-science contexts more interesting than others, and, if so, what are the sources of these differences? We draw on three sources of student data to answer this question: (1) quantitative survey data illustrating how interested students were in particular contexts from the curriculum, (2) qualitative survey data in which students describe the source of their interest in these particular contexts, and (3) interview data in which students reflect on the contexts that were and were not of interest to them. We find that examples that make interdisciplinary connections with students’ other coursework in biology and chemistry, and examples that make connections to what students perceive to be the “real world,” are particularly effective at fostering interest. More generally, students describe being deeply engaged with contexts that foster a sense of coherence or have personal meaning to them. We identify various “engagement pathways” by which different life-science students engage with IPLS content, and suggest that a curriculum needs to be flexible enough to facilitate these different pathways

    What are the long-term drivers of food prices? Investigating improvements in the accuracy of prediction intervals for the forecast of food prices

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    Over the last few years, the prices of the main agricultural raw materials have been highly volatile. The situation is unprecedented, both in the magnitude of the upward and downward volatility observed, and in the number of agricultural commodities affected. Various factors are contributing to these contrasting shifts: the role of emerging countries, changing dietary habits, an increase in energy demand related to the boom in biofuels, adverse weather conditions and speculation. In this paper we try to capture long-term relationships between crop prices and crude oil price using a partial equilibrium and times series method. The study finds little empirical evidence that the crude oil price have a significant influence on the variation of major vegetable crops pricesPartial equilibrium modeling, Forecasting cointegration, Demand and Price Analysis, Q11, Q13, Q42,

    On the complementarity of galaxy clustering with cosmic shear and flux magnification

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    In this paper, we motivate the use of galaxy clustering measurements using photometric redshift information, including a contribution from flux magnification, as a probe of cosmology. We present cosmological forecasts when clustering data alone is used, and when clustering is combined with a cosmic shear analysis. We consider two types of clustering analysis: firstly, clustering with only redshift auto-correlations in tomographic redshift bins; secondly, using all available redshift bin correlations. Finally, we consider how inferred cosmological parameters may be biased using each analysis when flux magnification is neglected. Results are presented for a Stage III ground-based survey, and a Stage IV space-based survey modelled with photometric redshift errors, and values for the slope of the luminosity function inferred from CFHTLenS catalogues. We find that combining clustering information with shear can improve constraints on cosmological parameters, giving an improvement to a Dark Energy Task Force-like figure of merit by a factor of 1.33 when only auto-correlations in redshift are used for the clustering analysis, rising to 1.52 when cross-correlations in redshift are also included. The addition of galaxy-galaxy lensing gives further improvement, with increases in figure of merit by a factor of 2.82 and 3.7 for each type of clustering analysis respectively. The presence of flux magnification in a clustering analysis does not significantly affect the precision of cosmological constraints when combined with cosmic shear and galaxy-galaxy lensing. However if magnification is neglected, inferred cosmological parameter values are biased, with biases in some cosmological parameters larger than statistical errors. (Abridged)Comment: Accepted by MNRAS, 18 pages, 12 Figures, 3 Table
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