1,721,216 research outputs found
The finite mixture model for the tails of distribution: Monte Carlo experiment and empirical applications
No full textThe finite mixture model estimates regression coefficients distinct in each of the different groups of the dataset endogenously determined by this estimator. In what follows the analysis is extended beyond the mean, estimating the model in the tails of the conditional distribution of the dependent variable within each group. While the clustering reduces the overall heterogeneity, since the model is estimated for groups of similar observations, the analysis in the tails uncovers within groups heterogeneity and/or skewness. By integrating the endogenously determined clustering with the quantile regression analysis within each group, enhances the finite mixture models and focuses on the tail behavior of the conditional distribution of the dependent variable. A Monte Carlo experiment and two empirical applications conclude the analysis. In the well-known birthweight dataset, the finite mixture model identifies and computes the regression coefficients of different groups, each one with its own characteristics, both at the mean and in the tails. In the family expenditure data, the analysis of within and between groups heterogeneity provides interesting economic insights on price elasticities. The analysis in classes proves to be more efficient than the model estimated without clustering. By extending the finite mixture approach to the tails provides a more accurate investigation of the data, introducing a robust tool to unveil sources of within groups heterogeneity and asymmetry otherwise left undetected. It improves efficiency and explanatory power with respect to the standard OLS-based FMM
Immunomodulators and enzymes of purine metabolism in human lymphocytes. Ambrogi F, Petrini M, Azzara A, Carulli G, Caracciolo F, Grassi B, Bertelli A.
No full textThe enzymes ADA and PNP were evaluated in lymphocytic subpopulations in peripheral blood obtained from healthy subjects, elderly subjects and patients with immunoproliferative diseases. Some similar assessments were performed on lymphoid cells from cord blood. Preliminary studies indicate that Thymostimulin can in some cases correct enzymic defects
Plastic-free behavior of millennials: An application of the theory of planned behavior on drinking choices
Full text linkThis study explores the factors that influence millennials’ intentions and behavior regarding reduced plastic consumption. An extended theory of planned behavior was established as a conceptual model that explicitly analyzed both the role of past and stated behaviors. The stated behavior was measured using a projective technique. The data obtained from a survey of 741 Italian respondents were analyzed through multiple correspondence analysis and partial least squares structural equation modeling. The results of the projective technique characterized “plastic-free” behavior as a unidimensional construct. Structural equation modeling showed that attitudes, subjective norms, and perceived behavioral control influence the intention of millennial consumers to reduce the use of plastic drinking bottles. The perceived behavioral control is the strongest predictor of intention (ß = 0.304; p < 0.001), followed by social norms (ß = 0.271; p < 0.001) and attitudes (ß = 0.130; p < 0.001). The past behavior construct positively and significantly affects attitude (ß = 0.165; p < 0.001), intention (ß = 0.231; p < 0.001), and stated behavior (ß = 0.073; p < 0.05) constructs. The latter is also positively predicted by intention (ß = 0.151; p < 0.001). Based on the results, actions and incentives for reducing plastic consumption were provided
Organic farming increases the technical efficiency of olive farms in Italy
No full textWhile there is growing recognition of the positive role played by organic farming in the reduction of the negative externalities due to conventional agriculture, there is uncertainty about the effect of the latter on the economic performance of the farms. In this scenario, the present paper aims at investigating the effect of organic farming on technical efficiency in Italian olive farms. A cross‐section dataset was analyzed through the stochastic frontier function, where the adoption of organic farming was explicitly modeled. Then, to obtain an unbiased estimate of the impact of organic farming on technical efficiency, a propensity score matching method was implemented. The findings reveal that organic farming increases technical efficiency in Italian olive farms by approxi-mately 10%. The highest impact of organic farming is observed in small farms. As for the propensity to become organic, we found that the production and the direct sales of a higher quality of gross marketable output, as well as the intensity of labor and machines, increase the probability to adopt organic farming. Conversely, farm localization, the availability of family labor, and financial capital discourage conversion to the organic farming system
Simple and direct communication of dynamical supersymmetry breaking
Full text linkWe present a complete, calculable, and phenomenologically viable model of dynamical supersymmetry breaking. The model is a simple extension of the so called 3- 2 model, with gauge group SU(3) × SU(2) × GSM and the MSSM fields directly coupled to the hidden sector SU(2) vector fields. Sfermion masses are universal, thus solving the supersymmetric flavour problem, and gaugino masses are not suppressed, in fact they are predicted to be of the same order as sfermion masses. Sizeable contributions to the MSSM A-terms can be generated, depending on the size of some free couplings. As a byproduct, we show some properties of a class of models with n pairs of Higgs doublets
Effects of Insurance Adoption and Risk Aversion on Agricultural Production and Technical Efficiency: A Panel Analysis for Italian Grape Growers
No full textThis article aims to evaluate the effect of insurance on production, technical efficiency, and input use of Italian specialised-quality grape growers. A panel instrumental variable stochastic frontier approach is applied over the years 2008–2017 using data from the Farm Accountancy Data Network. The results show the requirement to correct for the endogeneity that stems from insurance adoption. Insurance has an enhancing effect on production and efficiency and reduces the use of intermediate inputs. It suggests that insurance helps to diminish the risk-averse farmers’ suboptimal input use due to the presence of uncertainty. Crop insurance leads risk-averse farmers to behave as if they were risk neutral and employs the profit-maximising input vector. Therefore, by reducing the risks linked to the uncertainty of outcomes, crop insurance leads grape growers to go in the direction of profit maximisation
Hedonic pricing applied to wine from an Italian grape variaty
No full textConsumers face complex choices when buying wine, a highly differentiated product sold at widely
varying prices. This paper aims to provide a monetary valuation of some key credence attributes
of wine, such as certifications and quality ratings made by expert tasters. The implicit price
of DOC-DOCG certification is of extreme importance. It gives access to a collective reputation and
enables a premium price to be captured from consumers. With this in mind, hedonic price estimation
was performed on a specific Italian grape variety (Aglianico)
P-glycoprotein and treatment with plicamycin + hydroxyurea in myeloid blastic crisis of chronic myeloid leukemia
No full textThe authors studied P-glycoprotein (P-gp) expression in three patients affected by myeloid blast crisis of chronic myeloid leukemia undergoing chemotherapy with plicamycin + hydroxyurea. P-gp is the molecular marker of multidrug resistance (MDR), and is able to promote the efflux of various drugs (including plicamycin) from the neoplastic cell. When resistance towards plicamycin and hydroxyurea association was observed, the blasts obtained from the three patients were found to express P-gp. Although P-gp may be not the unique mechanism responsible for resistance towards plicamycin and hydroxyurea association, the MDR phenotype may play an important role in the resistance towards this treatment protocol in the blast crisis of chronic myeloid leukemia
Farmers’ environmental awareness: Construct development, measurement, and use
No full textThis paper aims to contribute to the empirical measurement of farmers’ environmental awareness, and improve the understanding of the role of environmental awareness in farmers’ adoption of cleaner agricultural practices. We provide a theoretical and methodological framework for measuring environmental awareness as a multi-dimensional concept. The data obtained from a survey of 382 farmers in northern Serbia are used as an empirical basis to test the developed latent environmental awareness construct. This construct includes several domains: environmental knowledge, biospheric concern, connectedness to nature, environmental attitudes, and environmental behavior. The results show that environmental knowledge contributes the most to explaining the environmental awareness construct (factor loading = 0.83), whereas biospheric concern contributes the least (factor loading = 0.23). Regarding agricultural practices, environmental awareness is higher among farmers who use biological pest control (+23%), mulching (+17%), and green manure (+9%). Thus, our results uncover the role of farmers’ environmental awareness in the adoption of more sustainable agricultural practices. These results document the operational validity of the construct and its potential use in research activities and management programs geared toward promoting environmentally friendly food production
Irrigation water economic value and productivity: An econometric estimation for maize grain production in Italy
No full textClimate change, characterized by rising temperatures and limited precipitation, has intensified the demand for irrigation water while simultaneously restricting its availability. This challenge poses significant risks to agricultural and food production, particularly in the Mediterranean regions where, recently, water deficits have led to substantial production losses and quality issues. Water is a critical determinant of crops' economic viability, especially for water-intensive crops, making it essential to estimate its economic relevance, especially in the absence of reliable water market prices. This study has two primary objectives: first, to evaluate the shadow price of irrigation water for maize grain at the farm level, which is defined as the value generated by the marginal unit of water consumed; and second, to analyse its heterogeneity. Leveraging a Farm Accountancy Data Network (FADN) panel of 1625 Italian farms over a decade (2010–2020), an econometric production function approach is employed. Moreover, quantile regressions reveal variations in the shadow price linked to geographical, managerial, and structural farm characteristics. Our findings underscore water's key role in economically viable maize grain production, significantly enhancing the productivity of other inputs like fertilizers and pesticides. The average shadow price is 0.29 €/m3, with a median of 0.20 €/m3 and water total productivity accounts for one-third of maize's average gross output. Quantile regressions uncover how factors like geographic location, altitude, farm management, irrigation water source, and farm size influence the distribution of water productivity, reflecting either efficient use or scarcity of this resource. Our estimation provides valuable insights for policymakers by offering accurate shadow price estimates for irrigation water in Italian maize grain production. Furthermore, it enhances our understanding of irrigation water's role in the economic viability of this crop, while contributing to support evidence-based water management strategies, identifying vulnerable areas and farms and allowing for future methodological developments
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