Multiple goals in farmers’ decision making: The case of sheep farming in western Greece

Management strategies and performance differ among farmers, as a result of different, multiple and often conflicting goals. Many approaches to building farm level models that incorporate multiple goals have been developed over the years, most of which share a common weakness. The determination of the goals to be used as attributes in the utility function is the result of a highly interactive process with the individual farmer, often difficult to implement. In this study, we use a non-interactive methodology, described in recent literature, to elicit the utility function of selected sheep farmers in western Greece, since farmers often appear reluctant to answer straightforward questions about their goals and preferences. Τhe results indicate that sheep farmers aim at the achievement of multiple goals, and that the maximization of gross margin is an important attribute in the utility function of mainly larger farms with a commercial orientation. The minimization of purchased forage, family labor and cost of hired labor are also important goals, especially for small and less commercial family farms. The multi objective farm level model built reproduces the Greek sheep farmers’ behavior more accurately and can replace the single objective model in decision making or agricultural planning problems

A multi-criteria model to analyze decision making in different farm structures: The case of dairy sheep farming in Greece

Optimization models commonly used in agricultural studies assume profit maximization as the only objective of farmers. But the existence of diversified farm structures is, at a certain extent, the result of individual preferences and objectives. In this study we aim at building a mathematical model to study the behaviour of Greek sheep farmers. A non-interactive methodology is used to assess the utility function of farmers, which is then optimized subject to the constraint set. The results of the analysis indicate the multi-attribute form of the utility function and point out the ability of the model to accurately reproduce farmer’s behaviour

Utility-derived supply function of sheep milk: the case of Etoloakarnania

Dairy sheep farming is an important agricultural activity in Greece, since it contributes significantly to the country’s gross agricultural production value. In this study, we suggest the use of multi-criteria analysis to estimate the supply response of sheep milk to price. The study focuses on the Prefecture of Etoloakarnania, located in Western Greece, where sheep farming is a common and traditional activity. A non-interactive technique is used to derive farmers’ individual utility functions which are then optimised parametrically, subject to technico-economic constraints, to estimate the supply function of sheep milk. Detailed data from selected farms representing different farm types and management strategies have been used in the analysis. The results indicate that the multi-criteria model reflects the actual operation of the farms more accurately than the gross margin maximisation model and therefore leads to a more robust estimation of the milk supply

The impact of different energy policy options on feedstock price and land demand for maize silage: the case of biogas in Lombardy

The growing demand of maize silage for biogas production in Northern Italy has triggered an intense debate concerning land rents, maize prices and their possible negative consequences on important agri-food chains. The aim of this work is to quantify the extent to which the rapid spread of biogas raised the maize price at regional level, increasing the demand of land for energy crops. For this purpose we applied a partial-equilibrium framework simulating the agricultural sector and the biogas industry in Lombardy, under two alternative schemes of subsidization policy. Results show that policy measures implemented in 2013 \u2013 reducing the average subsidy per kWh \u2013 may contribute to enforce the complementarity of the sector with agri-food chains, decreasing the competition between energy and non-energy uses. Compared to the old scheme, maize demand for biogas would decrease , lessening the market clearing price (as well as feed opportunity cost for livestock sector) and reducing land demand for energy purposes

Photometry of GSC 762-110, a new triple-mode radially pulsating star

Stars pulsating in three radial modes are very rare; only three examples are known in the Galaxy. These stars are very useful since their periods may be measured very precisely, and this will constrain the global stellar parameters and the models of the star's interior. The purpose of this paper is to present a new example of the class of triple-mode radial pulsators. A search for candidate multi-mode pulsators was carried out in public survey data. Time-series photometry of one of the candidates, GSC 762-110, was performed. GSC 762-110 was found to be a triple-mode radial pulsator, with a fundamental period of 0.1945d and period ratios of 0.7641 and 0.8012. In addition two non-radial modes were found, for which the amplitude has diminished considerably over the last few years.Comment: Accepted for publication in Astronomy & Astrophysic

The impact of different energy policy options on feedstock price and land demand for maize silage: the case of biogas in Lombardy

The growing demand of green maize for biogas production in Northern Italy has triggered an intense debate concerning land rents, maize prices and their possible negative consequences on important agri-food chains. The aim of this work is to quantify the extent to which the rapid spread of biogas raised the maize price at regional level, increasing the demand of land for energy crops. For this purpose we built a partial-equilibrium model simulating the agricultural sector and the biogas industry in Lombardy, under two alternative subsidization schemes. Results show that policy measures implemented in 2013 \u2013 reducing the average subsidy per kWh \u2013 may contribute to enforce the sustainability of the sector and decreasing its competition with agri-food chains: maize demand for biogas would decrease, compared to the old scheme, lessening the market clearing price and reducing land demand for energy purposes

Scaffold-mediated Nucleation of Protein Signaling Complexes: Elementary Principles

Proteins with multiple binding sites play important roles in cell signaling systems by nucleating protein complexes in which, for example, enzymes and substrates are co-localized. Proteins that specialize in this function are called by a variety names, including adapter, linker and scaffold. Scaffold-mediated nucleation of protein complexes can be either constitutive or induced. Induced nucleation is commonly mediated by a docking site on a scaffold that is activated by phosphorylation. Here, by considering minimalist mathematical models, which recapitulate scaffold effects seen in more mechanistically detailed models, we obtain analytical and numerical results that provide insights into scaffold function. These results elucidate how recruitment of a pair of ligands to a scaffold depends on the concentrations of the ligands, on the binding constants for ligand-scaffold interactions, on binding cooperativity, and on the milieu of the scaffold, as ligand recruitment is affected by competitive ligands and decoy receptors. For the case of a bivalent scaffold, we obtain an expression for the unique scaffold concentration that maximally recruits a pair of monovalent ligands. Through simulations, we demonstrate that a bivalent scaffold can nucleate distinct sets of ligands to equivalent extents when the scaffold is present at different concentrations. Thus, the function of a scaffold can potentially change qualitatively with a change in copy number. We also demonstrate how a scaffold can change the catalytic efficiency of an enzyme and the sensitivity of the rate of reaction to substrate concentration. The results presented here should be useful for understanding scaffold function and for engineering scaffolds to have desired properties.Comment: 12 pages, 8 figure

Grb2 monomer-dimer equilibrium determines normal versus oncogenic function

The adaptor protein growth factor receptor-bound protein 2 (Grb2) is ubiquitously expressed in eukaryotic cells and involved in a multitude of intracellular protein interactions. Grb2 plays a pivotal role in tyrosine kinase-mediated signal transduction including linking receptor tyrosine kinases to the Ras/mitogen-activated protein (MAP) kinase pathway, which is implicated in oncogenic outcome. Grb2 exists in a constitutive equilibrium between monomeric and dimeric states. Here we show that only monomeric Grb2 is capable of binding to SOS and upregulating MAP kinase signalling and that the dimeric state is inhibitory to this process. Phosphorylation of tyrosine 160 (Y160) on Grb2, or binding of a tyrosylphosphate-containing ligand to the SH2 domain of Grb2, results in dimer dissociation. Phosphorylation of Y160 on Grb2 is readily detectable in the malignant forms of human prostate, colon and breast cancers. The self-association/dissociation of Grb2 represents a switch that regulates MAP kinase activity and hence controls cancer progression

p66 Shc and tyrosine-phosphorylated Shc in primary breast tumors identify patients likely to relapse despite tamoxifen therapy

INTRODUCTION: Shc adapter proteins are secondary messenger proteins involved in various cellular pathways, including those mediating receptor tyrosine kinase signaling and apoptosis in response to stress. We have previously reported that high levels of tyrosine-phosphorylated Shc (PY-Shc) and low levels of its inhibitory p66 Shc isoform are strongly prognostic for identifying both early node-negative and more advanced, node-positive, primary breast cancers with high risk for recurrence. Because aberrant activation of tyrosine kinases upstream of Shc signaling proteins has been implicated in resistance to tamoxifen – the most widely prescribed drug for treatment of estrogen receptor-positive breast cancer – we hypothesized that Shc isoforms may identify patients at increased risk of relapsing despite tamoxifen treatment. METHODS: Immunohistochemical analyses of PY-Shc and p66 Shc were performed on archival primary breast cancer tumors from a population-based cohort (60 patients, 9 relapses) and, for validation, an independent external cohort (31 patients, 13 relapses) in which all patients received tamoxifen as a sole systemic adjuvant prior to relapse. RESULTS: By univariate and multivariate analyses, the Shc proteins were very strong and independent predictors of treatment failure in both the population-based cohort (interquartile hazard ratio = 8.3, 95% confidence interval [CI] 1.8 to 38, P = 0.007) and the validating cohort (interquartile relative risk = 12.1, 95% CI 1.7 to 86, P = 0.013). CONCLUSION: These results suggest that the levels of PY-Shc and p66 Shc proteins in primary tumors identify patients at high risk for relapsing despite treatment with tamoxifen and therefore with further validation may be useful in guiding clinicians to select alternative adjuvant treatment strategies