Estimating a production function under production and price risks: An application to the suckler cow farms in the French charolais production area

Suckler cow production in France relies mainly on a relatively extensive management of forage, implying that production risk may be enhanced by the sensitivity of those crops to weather variability. However risk exposure is supposed to be mitigated either through ex-ante decisions concerning pasture area management or through ex-post decisions concerning the purchase of feeds. This paper aims at assessing weather impacts on cattle production level decisions. Since farmers' decisions depend on farmers' behaviour regarding risks, which are namely production and price risks, we test constant absolute risk aversion, constant relative risk aversion and risk neutrality assumptions. We develop an econometric model encompassing an auto-regressive price function and a production function which allow inputs to affect independently mean and variance of the production. Weather indicators embodied by average regional forage production for current and past years are explicitely introduced as non controllable inputs. The estimation framework consist in conditions on the first and second moment of output production, output price and profit. Following, ISIK (2003), additional condition on each of both allocable inputs enable us to take into account risk aversion and both price and production risks in parameters estimation. We use the Generalized Method of Moments in order to make minimum assumptions regarding variable exogeneity and error distribution. We apply the model to an original panel dataset containing 65 individual yearly observations recorded over the period 1987-2005 on French suckler cow farms of the north of Massif Central. Because of the difficulties to find a relevant set of instruments, these preliminary results do not analyse weather impact on production mean. However we can advance that production decisions depend on price and production risks as farmers are found to be risk averse. Weather variability of the current year increase production risk whereas fertilizer level application slightly increased it. However we did not highlight that weather impact depend on production level.Production function estimation, GMM, weather impact, price and production risks, risk aversion, suckler cow farms, French charolais production area, Livestock Production/Industries, Production Economics,

Une mesure de l'effet de la délégation sur le prix de l'eau potable en France

Un peu plus de la moitié des communes françaises délègue actuellement la gestion du service de l'eau à des entreprises privées. L'incidence de ce choix du mode de gestion sur le coût du service et l'ampleur des différences observées entre modes de gestion privée ou publique sont des questions d'actualité. Une évaluation des effets sur le niveau des prix de la délégation des services de l'eau potable en France montre que les conditions d'exploitation de ces services permettent d'expliquer en grande partie l'écart de prix existant entre la moyenne des prix pratiqués par les délégataires privés et celle constatée pour les régies en 1998. Ces résultats confortent l'idée que les communes ont tendance à choisir la gestion privée si elles font face à des conditions d'exploitation difficiles.

Prospects for studies of the free fall and gravitational quantum states of antimatter

Different experiments are ongoing to measure the effect of gravity on cold neutral antimatter atoms such as positronium, muonium and antihydrogen. Among those, the project GBAR in CERN aims to measure precisely the gravitational fall of ultracold antihydrogen atoms. In the ultracold regime, the interaction of antihydrogen atoms with a surface is governed by the phenomenon of quantum reflection which results in bouncing of antihydrogen atoms on matter surfaces. This allows the application of a filtering scheme to increase the precision of the free fall measurement. In the ultimate limit of smallest vertical velocities, antihydrogen atoms are settled in gravitational quantum states in close analogy to ultracold neutrons (UCNs). Positronium is another neutral system involving antimatter for which free fall under gravity is currently being investigated at UCL. Building on the experimental techniques under development for the free fall measurement, gravitational quantum states could also be observed in positronium. In this contribution, we review the status of the ongoing experiments and discuss the prospects of observing gravitational quantum states of antimatter and their implications.Comment: This work reviews contributions made at the GRANIT 2014 workshop on prospects for the observation of the free fall and gravitational quantum states of antimatte

Estimating a Production Function under Production and Output Price Risks: An Application to Beef Cattle in France

This paper addresses the issue of agricultural production under both output level and output price risks, in a context of random climatic conditions affecting forage used in beef production. It contributes to the empirical literature by applying the framework proposed by Isik (2002) to derive estimating equations from a structural production model with two sources of risks. Flexible functional forms for risk preferences and production technology allow us to identify attitudes toward risk and compute marginal effects of inputs and climate on expected output and production risk. The model is applied on a panel of French cattle farms and estimation results suggest that cattle farmer exhibit strong risk aversion of the CRRA form, and that climate has a significant impact on the performance of animal feeding strategies

Transverse-mode selective resonant grating-mirrors for high power and high brightness emission

International audienceThe finite angular spectral width of a 2D resonant grating mirror is adjusted to select the fundamental transverse mode of a laser and to filter out higher order modes. The selection principle is explained phenomenologically on a simplified 1D model. The 2D design is made so as to sustain the large field concentration in the grating slab-waveguide mirror, and the technology permitting to obtain the resonant reflection within the gain bandwidth of two types of laser is described. The blank experimental measurements by means of a white light supercontinuum are shown to match the targeted specifications on the resonance spectral position and angular width

Estimating a Production Function under Production and Output Price Risks: An Application to Beef Cattle in France

This paper addresses the issue of agricultural production under both output level and output price risks, in a context of random climatic conditions affecting forage used in beef production. It contributes to the empirical literature by applying the framework proposed by Isik (2002) to derive estimating equations from a structural production model with two sources of risks. Flexible functional forms for risk preferences and production technology allow us to identify attitudes toward risk and compute marginal effects of inputs and climate on expected output and production risk. The model is applied on a panel of French cattle farms and estimation results suggest that cattle farmer exhibit strong risk aversion of the CRRA form, and that climate has a significant impact on the performance of animal feeding strategies

Experimental investigation of amplitude and phase quantum correlations in a type II OPO above threshold: from the non-degenerate to the degenerate operation

We describe a very stable type II optical parametric oscillator operated above threshold which provides 9.7 $\pm$ 0.5 dB (89%) of quantum noise reduction on the intensity difference of the signal and idler modes. We also report the first experimental study by homodyne detection of the generated bright two-mode state in the case of frequency degenerate operation obtained by introducing a birefringent plate inside the optical cavity