961 research outputs found

    Style and Performance of Agricultural Market Advisory Services

    Get PDF
    This paper describes the degree of marketing activeness of market advisory programs for corn and soybeans, and analyzes the relationship between activeness degree and pricing performance. The data set employed consists of advisory programs tracked by the AgMAS Project at the University of Illinois between 1995 and 2001. Cluster analysis was conducted to group the programs according to their degree of activeness. Panel data regression models were estimated to evaluate the relationship between activeness degree and pricing performance. In the corn market, point estimates indicate a positive effect of the degree of activeness on pricing performance, but this effect is of small magnitude and statistically insignificant. For soybeans,there is a stronger positive relationship between activeness degree and performance, with an estimated effect of activeness on performance larger in magnitude and statistically significant. This positive relationship suggests that active marketing programs are based on superior information and/or analytical skills.Agribusiness, Marketing,

    Biovolume determination of phytoplankton guilds in transitional water ecosystems of Mediterranean Ecoregion

    Get PDF
    1 - Conceptually, morphometric measurements of phytoplankton guilds seem to have major advantages as descriptors of the ecological status of transitional water ecosystems (TW) with respect to classical taxonomic descriptors. However, at present, standardized or common methodologies for the use of morphometric descriptors do not exist. 2 - This paper aims to provide a starting point for the activation of standardized methods for the determination of morphometric descriptors of phytoplankton as a quality element in TW in accordance with the new directive of WFD 2000/60/EU. 3 - Phytoplankton biovolume is one of the most studied morphometric descriptors. It can be estimated by associating the algae with similar geometric forms and determining the volume of these by measuring the linear dimensions required for its calculation under the microscope. However, the lack of a standardized set of geometric forms and equations for calculating biovolume causes difficulties and produces data that are not comparable. 4 - A set of geometric models is suggested here for calculating the cell biovolumes of 201 phytoplankton genera found in transitional water ecosystems of Mediterranean Ecoregion. The equations were designed to minimize the effort of microscopic measurements. The main methodological problems, and the similarities and differences between our own and previously published proposals are discussed

    PORTFOLIOS OF AGRICULTURAL MARKET ADVISORY SERVICES: HOW MUCH DIVERSIFICATION IS ENOUGH?

    Get PDF
    Agricultural market advisory services offer specific advice to farmers on how to market their commodities. Farmers can subscribe to one or more of these services and follow their advice as a way of managing price risk. According to portfolio theory, a combination of these services may have risk/return benefits compared to individual services. This report analyzes the potential risk reduction gains from naïve diversification among market advisory services for corn and soybeans. Results show that increasing the number of (equal-weighting) services reduces portfolio expected risk, but the marginal decrease in risk from adding a new service decreases rapidly with portfolio size. The risk reduction benefits of naïve diversification among advisory services is relatively small compared to the results obtained in previous studies for stock portfolios, and this is mainly because advisory prices, on average, are highly correlated. A one service portfolio has only a 20%, 16% and 32% higher expected standard deviation than the minimum risk naïve portfolio for corn, soybeans and 50/50 revenue, respectively. Most risk reduction benefits are achieved with small portfolios. For instance, a four service portfolio has only 5%, 4% and 9% higher expected standard deviation than the minimum risk naïve portfolio for corn, soybeans and 50/50 revenue, respectively. Based on these results, there does not appear to be strong justification for farmers adopting portfolios with a large number of advisory services. Farmers may well choose portfolios with as few as two or three programs, since the relatively high total subscription costs associated with larger portfolios can be avoided while obtaining most of the benefits from diversification.Marketing,

    Costos Ambientales y Eficiencia Productiva en la Producción Agraria del Partido de Pergamino

    Get PDF
    Mediante un modelo de frontera de producción estocástica se analizó el nivel de eficiencia técnica para la producción de soja, maíz y trigo en empresas agropecuarias del partido de Pergamino, Buenos Aires, Argentina. El costo asociado a tres indicadores ambientales: balances de nutrientes, balance de materia orgánica y erosión hídrica, se consideró como parte de los insumos de producción. En promedio, la soja 1ra es el cultivo con costo ambiental más elevado, con un costo ambiental 53u s/hamayorqueenlasecuenciatrigo/sojay76us /ha mayor que en la secuencia trigo/soja y 76 u s /ha mayor que en maíz. Se estimó un nivel de eficiencia promedio del 85%. Si bien este valor implica la posibilidad de aumentar un 15% la producción para un mismo nivel de insumos, es un valor elevado si se lo compara con mediciones realizadas en otros sistemas agrícolas extensivos. Aunque un alto nivel de eficiencia es consistente con un buen uso de los recursos, los resultados sugieren que es posible reducir los costos ambientales de los sistemas de producción mediante cambios en la combinación de cultivos. En la actualidad existe una fuerte predominancia del cultivo de soja en toda la región agrícola de Argentina. Una mayor superficie de cultivos con menores costos ambientales podría conseguirse mediante la implementación de políticas que fomenten estas producciones.A stochastic frontier model is employed to analyze technical efficiency for soybeans, corn and wheat production in commercial farms in Pergamino, Buenos Aires, Argentina. The cost associated with three environmental indicators: nutrients balances, organic carbon balance and water erosion, is modeled as an input for efficiency estimation. On average, growing soybeans has an environmental cost 53 u s/hahigherthangrowingthedoublecropwheat/soybeansand76us /ha higher than growing the double crop wheat/soybeans and 76 u s /ha higher than growing maize. Estimated average efficiency for agricultural production is 85%. This value indicates the possibility of increasing production by 15% while keeping the inputs level constant. This efficiency level is high compared to efficiency estimates for extensive agricultural systems reported by other authors. While a high efficiency level is consistent in a good use of available resources, results suggest the possibility of reducing environmental costs through changes in land allocation Currently, land share for soybeans is the highest of all crops in the main agricultural region. A larger share of crops with lower environmental costs could be achieved with policies that provide incentives for increasing the planting area for these crops

    Effect of cyclic loading on hydrogen diffusion in low carbon steels

    Get PDF
    Carbon steels or low-alloyed steels may be affected by damaging phenomena due to Hydrogen Embrittlement (HE), which is a particular form of Environmental Assisted Cracking (EAC). The insurgence of HE depends on the intrinsic susceptibility of the steel, the applied stress, and the concentration of hydrogen inside the metal. It occurs by a mechanism of absorption and subsequent diffusion of atomic hydrogen through the metal lattice. On steels with a yield strength lower than 700 MPa, HE occurs in the plastic deformation field, in the presence of dynamic loading at slow strain rates or cyclic fatigue loading at very low frequencies. Although several important studies were carried out on the effect of loading conditions on hydrogen diffusion into the metal and HE mechanism, HE phenomena are not fully understood. In this work, the effect of the application of cyclic loads on hydrogen diffusion parameters was studied both in the elastic and in the plastic deformation field. The influence of mean load and amplitude was analyzed. Hydrogen permeation tests were performed on API 5L X65 steel, in accordance with ISO 17081:2014. The specimen behaved as bi-electrode between the two compartments of a Devanathan-Stachurski cell. The anodic side of the specimen was polarized at +340 mV vs Ag/AgCl in a 0.1 M NaOH aerated solution, while the cathodic compartment was filled with an aerated borate solution. A controller enabled temperature adjustment at 20±0.5°C. Once the passivity current registered in the anodic side reached values of 0.05 µA/cm2, a cathodic current density of 0.50 mA/cm2 was applied to charging cathodic side. The study included tests with sine waveform cycling loading, with a maximum level equal to 110% TYS, at a frequency of 10-2 Hz. The results confirmed the values of hydrogen diffusion coefficient usually indicated for low-alloyed steels with a sorbitic microstructure. Strain hardened specimens - stretched above yield strength - showed an increase of steady state current and an extension of the time lag, denoting a slight decrease in the apparent hydrogen diffusion coefficient due to traps effect in the cold deformed steel matrix. Under cyclic loading, an instantaneous peak of current with a subsequent significant transient decrease occurred after cyclic load application, whereas no relevant variation of permeation curve compared to unloaded specimens was observed if specimens were already loaded before hydrogen charging. The instantaneous current peak reached values much higher than the steady state current. This is ascribed to the rupture of the passive film – caused by loading – and its subsequent reformation; in fact, this can also be noted during tests performed on specimens without hydrogen permeation. The following transient, in which the permeation current decreases below the steady state and then returns to it, denotes a relevant trapping effect that causes the instantaneous reduction of mobile hydrogen concentration in the lattice. This becomes more significant for loads closer and closer to the yield strength, mainly beyond this, and can only be noted at the first loading step. Subsequent unloading and loading step at the same mean value showed no transient in the permeation curren

    Chemical Raman Enhancement of Organic Adsorbates on Metal Surfaces

    Get PDF
    Using a combination of first-principles theory and experiments, we provide a quantitative explanation for chemical contributions to surface-enhanced Raman spectroscopy for a well-studied organic molecule, benzene thiol, chemisorbed on planar Au(111) surfaces. With density functional theory calculations of the static Raman tensor, we demonstrate and quantify a strong mode-dependent modification of benzene thiol Raman spectra by Au substrates. Raman active modes with the largest enhancements result from stronger contributions from Au to their electron-vibron coupling, as quantified through a deformation potential, a well-defined property of each vibrational mode. A straightforward and general analysis is introduced that allows extraction of chemical enhancement from experiments for specific vibrational modes; measured values are in excellent agreement with our calculations.Comment: 5 pages, 4 figures and Supplementary material included as ancillary fil
    corecore