403 research outputs found

    Rigorous Limits on the Interaction Strength in Quantum Field Theory

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    We derive model-independent, universal upper bounds on the Operator Product Expansion (OPE) coefficients in unitary 4-dimensional Conformal Field Theories. The method uses the conformal block decomposition and the crossing symmetry constraint of the 4-point function. In particular, the OPE coefficient of three identical dimension dd scalar primaries is found to be bounded by ~ 10(d-1) for 1<d<1.7. This puts strong limits on unparticle self-interaction cross sections at the LHC.Comment: 11 pp, 3 figs + data file attache

    Traceability and Demand Sensitiveness: Evidences from Italian Fresh Potatoes Consumption

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    When a traceability system takes place, either when mandatory or voluntary, many questions arise that need to be addressed and answered. One of the firsts concerns whether it introduces new costs with no gain in efficiency or, on the contrary, the system efficiency increases lowering costs and, as a consequence, market price of the good in hand. Among others, another issue that only rarely is addressed regards the effect of a price change on the final market. The objective of this paper was to simulate the effect on fresh Italian vegetables market of prices change due to a newer traceability procedure, focusing on early potato. Reasons why early potato was the main object of our study will be explained in detail later in the paper. Moreover, this study concerns a demand system estimation that has, as main goal, the measurement of own and cross price elasticities as well as expenditure elasticities. Such estimations are not strictly related with traceability because they measure any change in quantity demanded due to price changes due to any market perturbation. However, since early potato is experiencing a peculiar market and chain change in Italy, our simulation is meant to reason in terms of a “what if” approach, formally simulating the effect of any change in price due to an hypothesis of traceability system involved. In order to estimate a demand system, real household consumption data (3,000 observations) of a statistically representative sample of the Italian population of households was taken into account. Relevant measures of market variables were estimated by means of a Linear Almost Ideal Demand System implementing a large set of fresh vegetables: potato split in early and late, cabbage, salad, mushrooms, fruits vegetables, roots, asparagus, onion, tomatoes, peppers, cucumbers, beans, zucchinis and others.traceability, early potato, censored demand system estimation, sample selection approach., Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Research Methods/ Statistical Methods,

    The Perceived Impact of the In-Trust Agreements on CGIAR Germplasm Availability: An Assessment of Bioversity International's Institutional Activities

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    This study assesses the generation and consequences of the In-Trust Agreements (ITAs) that established the legal status of the CGIAR germplasm as freely available for the benefit of humanity under the auspices of FAO. The analysis looks at the history of the ITAs and focuses on the role of Bioversity International in research and other activities in influencing, facilitating and enabling the ITA negotiations. Results confirm the central role of Bioversity and policy research in the negotiations process. Concepts developed during the ITA negotiations contributed toward subsequent multilateral negotiations that eventually culminated in the International Treaty on Plant Genetic Resources

    Livelihood assets' influence on Ugandan farmers' control practices for Banana Xanthomonas Wilt (BXW)

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    AbstractThis study analyzes the influence of livelihood assets on Ugandan farmers' decisions to control Banana Xanthomonas Wilt (BXW), a disease that has threatened banana production and the livelihoods of Ugandan farmers since 2001. The BXW control strategy is based on the simultaneous implementation of four cultural practices: de-budding, infected plant removal, disinfecting tools, and using clean planting materials. The Sustainable Rural Livelihood (SRL) framework represents a very useful theoretical architecture for examining the interplay between livelihood systems of rural Ugandan households and the external context. Empirically, this study applies a double-hurdle model with the base assumption that the two adoption decision processes (whether to adopt and the intensity of adoption of the cultural practices) are separate. Results indicate that the vulnerability context and the human, social, natural, and physical capitals are the factors that drive farmers to adopt the identified strategy. Farmers' decisions about the extent of adoption are instead negatively influenced by natural capital and positively associated with social capital. These findings highlight the importance of supporting the improvement of livelihood assets to enable tailored support to farmers. It is particularly important to support the social and natural capitals that facilitate information exchange and provide critical resources for the adoption of the BXW control strategy

    Effects of Traceability on the Italian Fresh Vegetables Market: A Demand System Simulation

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    Traceability can serve various purposes in the food sector, including that of chain quality control. However, the aspects that seem to be most frequently required of traceability are those related to food safety. Nevertheless, traceability systems development has recently shifted its focus from the major aspects of food safety to a price premium search approach. Although such an approach often appears to lie behind production strategies, there is no technical or theoretical evidence to support it: traceability systems do not guarantee, per se, quality. On the other hand, a rigorous traceability system that pursues multiple objectives involves costly procedures that are very likely to feed all the way up to the consumer side. (more.....

    Traceability and Demand Sensitiveness: Evidences from Italian Fresh Potatoes Consumption

    Get PDF
    When a traceability system takes place, either when mandatory or voluntary, many questions arise that need to be addressed and answered. One of the firsts concerns whether it introduces new costs with no gain in efficiency or, on the contrary, the system efficiency increases lowering costs and, as a consequence, market price of the good in hand. Among others, another issue that only rarely is addressed regards the effect of a price change on the final market. The objective of this paper was to simulate the effect on fresh Italian vegetables market of prices change due to a newer traceability procedure, focusing on early potato. Reasons why early potato was the main object of our study will be explained in detail later in the paper. Moreover, this study concerns a demand system estimation that has, as main goal, the measurement of own and cross price elasticities as well as expenditure elasticities. Such estimations are not strictly related with traceability because they measure any change in quantity demanded due to price changes due to any market perturbation. However, since early potato is experiencing a peculiar market and chain change in Italy, our simulation is meant to reason in terms of a “what if” approach, formally simulating the effect of any change in price due to an hypothesis of traceability system involved. In order to estimate a demand system, real household consumption data (3,000 observations) of a statistically representative sample of the Italian population of households was taken into account. Relevant measures of market variables were estimated by means of a Linear Almost Ideal Demand System implementing a large set of fresh vegetables: potato split in early and late, cabbage, salad, mushrooms, fruits vegetables, roots, asparagus, onion, tomatoes, peppers, cucumbers, beans, zucchinis and others

    The Origin, Development And Structure Of Demand For Plant Genetic Resources. The Impact Of The In Trust Agreements To The CGIAR Collections Availability

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    The objective of this paper is to explore how the demand of germplasm held by CGIAR genebanks changed over time in order to assess the possible influence of the 1994 In Trust Agreements on germplasm demand. The proposed theoretic model motivates the realistic hypothesis that the consequences of the In-Trust Agreements lead to an enhancement of CGIAR germplasm utilization. Therefore the paper firstly examines the classical literature on biodiversity’s valuation and its recent developments and subsequently it investigates the origin of the agricultural biodiversity’s economic value, providing a basic conceptual framework to infer on factors determining the demand for germplasm. Two Bayesian estimation frameworks are applied to the IRRI accessions distribution’s time-series to provide formal evidence to the hypothesis, exploiting Markov Chain Monte Carlo methods, Gibbs sampling in particular. Evidence suggests that the demand variation implies a change in the genetic collections economic value, impacting therefore on their direct use search value.Crop genetic resources, germplasm collection, search theoretic framework, count data, changepoints, O19, Q18, Q57, C11,

    Drinking wine at home: Hedonic analysis of sicilian wines using quantile regression

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    Abstract: In recent decades, the Sicilian wine industry has experienced a booming expansion because of the growing preferences of Italian consumers for Sicilian wines, especially in extra-regional markets. These consumers have been paying closer attention to Sicilian premium wines. For this reason, the objective of this study is to inform professional investors and wine managers about the consumer preferences with respect to the most important segment categories of domestically consumed Sicilian wines. Using the quantile regression technique, we analyzed the role of wine attributes and prices as an information tool in order to value for each wine segment the implicit price of the attributes affecting wine consumers\u2019 choices. The results indicate that Protected Designation of Origin (PDO) and Geographical Indication (PGI) certification is the main determinant in the wine price mechanisms and certified wines achieve premium prices that are progressively higher as the price level of the wine increases. Furthermore the effect of the brand on price formation seems to have a significant impact for low-end wines, whereas it has no specific impact on the price mechanism for high-end wines. Keywords: Consumer Scan Dataset, Geographic Origin, Hedonic Price, Robust Regression, Wine Consumptio

    Validation of a Psychometric Scale to Measure Consumers’ Fears of Modern Food Technologies

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     The main consumer trends in food sector are two: on the one hand there is a growing demand for modernity (functional foods, convenience foods, healthy foods such as low calories and low-sodium foods), on the other hand there is a increasing demands for naturalness (organic foods, natural foods, local products and typical products). Moreover, in recent years consumers’ fears of novel food technologies are well documented and several psychometric scales were tested for the analysis of consumer’s attitude towards new technology. Therefore the ability to identify population segments that have greater or lesser neophobia/neophilia, thus enabling identification of early adopters of innovative products, would be more and more useful.A survey which bore such considerations in mind was conducted on a representative sample of 355 people interviewed shortly after their shopping trip to super- and hyper-markets in Campania region. A questionnaire was submitted to sample in spring 2010. The questionnaire collected information about the perception of new food technologies, the perception of naturalness and their roles in determining consumer preferences for different food products. To collect information about consumers perceptions we adopted the FTNS scale (Food Technology Neophobia Scale) which represents a useful tool for assessing receptivity to foods produced by novel technologies.A specific section of the questionnaire covered a case study and gathered information about the willingness to buy food products that consumers can associate to a greater or lesser use of modern technologies and belonging to a specific set of six food categories: functional foods, low calories foods, convenience foods (ready to eat) typical foods, organic foods, short chain products.First findings confirm that FTNS scale is a good instrument for predicting individuals’ willingness to try foods produced using modern technologiesMoreover first results are consistent across the different types of products and technologies tested and thus provide consistent evidence of predictive validity
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