500 research outputs found

    Computational analysis of fission penetrability through double-humped barriers by exact and JWKB methods

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    After the discovery of the double-humped potential barrier, researchers have derived a host of expressions for the probability of tunnelling through such a barrier. It is generally believed that the penetrabilities obtained by using the various methods do not differ sufficiently to have significant effects on the analysis of experimental data on fission. However, some have expressed doubts concerning the use of the usual JWKB method and have offered improved approximate and Exact methods for developing penetrability expressions. This thesis is devoted to the quantitative comparison of penetrabilities from these expressions, and to the investigation of effects various methods will have on spontaneous and isomeric fission half-lives. Results from the penetrability expressions are compared in relation to the pure vibrational state energy levels, level heights, resonance widths, and the probability of penetrating the full barrier from its ground-state deformation

    State-dependent classical potentials

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    Since the inception of quantum mechanics, the classical limit has been an area of unease. Explanations proposed on this matter include the usage of Plank's constant, the decoherence parameter of the master's equation, or the quantum potential of Bohm's theory. An equally obscure related topic is the mixing of classical and quantum quantities in the dynamical equations. In this thesis, the subject of classical-quantum mixing will be studied. A method will be explored which will demonstrate one of several candidate methods whereby mixing may be removed and replaced by fully quantum non-relativistic equations. Through use of the quantum potential concept and the Feynman path integral, state-dependent forms of the classical scalar and vector potentials will be derived by assuming the existence of separate component wave functions for the particle and potential. The specific wave component | e attributed to the potential, will hold the effects of an environment. The resulting equations are devoid of classical potentials and can therefore be considered as purely quantum--no mixing takes place. The standard classical potentials emerge from the state-dependent equations by a condition which will be referred to as state-dependence reduction (SDR). Through SDR, the semi-quantum and purely quantum equations are qualitatively and quantitatively equivalent. The new purely quantum equations will be used both to interpret gauge symmetry and to clarify the reasoning behind the Aharonov-Bohm effect. It will be argued that the freedom of gauge is related to the freedom to choose from many different and distinct environments which reproduce the same experimental outcome. Likewise, the AB-effect is understood through the environment from which the topological structure of the electromagnetic field is represented. Several aspects of the environment responsible for the effective potentials will be calculated numerically for well-known physical situations including one-dimensional scattering, two-dimensional double-slit setup, two-dimensional Aharonov-Bohm effect, and the two-dimensional Dirac equation. The proposal of using state-dependent potentials to replace the semi-quantum equation represents a consistent generalization and unification of the quantum and classical potentials, and may offer some experimental results yet untapped

    Picking out a wine: Consumer motivation behind different quality wines choice

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    The quality scale of Italian wines is mainly organized in four categories: PDO, PGI, basic and bulk wine. Our analysis explicitly investigates the patterns and determinants of consumption for these four different types of wine by analyzing a representative sample of consumers from a traditional wine-producing country. This study provides for first time insights on quality perceptions of wines and verifies whether Italian consumers perceive significant differences among the different categories of wines. The overall results, obtained through a system of equation estimates, show that consumer motivations and wine consumption determinants change according to each different range of wine quality and thereby support a hierarchical scale of quality wines, as a fact consumers' motivation progressively changes as the quality scales of the wine increase or decrease. In addition, this study highlights for first time any differences in the consumption determinants between the PDO and the PGI wines in a national context and it suggests that the influence of the two different GI labels on the wine choice of consumers is truly different. Important insights were also provided for bulk wine whose consumption seems to be closely related to wine tourism and the desire to buy locally produced wines. Keywords: Basic wines, Bulk wines, Local wines, PDO, PG

    A Network Analysis for Environmental Assessment in Wine Supply Chain

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    In the agri-food sector, the Life Cycle Assessment method (LCA) is used to evaluate the environmental impact of a product. Within agri-food products, wine is among the most analysed products, not only for its economic importance but also for the environmental impact of its activity. The paper aims to identify the main trends in the wine sector revolving around environmental evaluation using the LCA method in the academic literature. The aim is to investigate the literature on life cycle assessment analysis of grape and wine production through the systematic grouping of papers into clusters of research. So, the purpose is to discuss the gaps and insights identified by the study in order to aid in the development of a comprehensive state of the art on the topic. Scopus and Web of Science were used to search all articles following a clear and replicable protocol. The results (keywords) were subjected to co-occurrence analysis using VOSviewer, after which the articles were further analysed. Through a bibliographic coupling analysis, the research results were grouped through a network analysis that allowed identifying the research trends on the topic. Three clusters were identified containing the main lines of research on the subject. The results show that nowadays the literature is focusing on concerns related to climate change and consumer awareness on sustainability issues and certifications as well as environmental impacts generated mainly in the production phase in the vineyard. The research results are of interest for future research on LCA analysis in the wine sector in order to contribute to the discussion on the current model in the global wine sector

    What's in organic wine consumer mind? A review on purchasing drivers of organic wines

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    Consumer interest in organic wine is growing, but the effects of organic label, consumer quality perception and the support for the benefits claim of organic wine are not yet fully understood and at times doubtful. The literature shows a very heterogeneous picture regarding consumer behaviour and preferences for organic wine. This study seeks to understand the link between organic wine and consumer' purchasing drivers. Using a systematic literature review, the paper explores the characteristics of consumer of organic wine, the motivation on consumer behaviour and preferences for organic wine, as well as the sensory quality and the presence of additives when evaluating wine quality and in shaping consumers' attitudes. The results show how socio-economic and psychological characteristics of consumer as well as quality perception affect their behaviour for organic wine. Little consensus on the benefits in terms of improved sensory quality of organic wine compared to conventional one. Among sensory qualities, taste has been found to be both a key driver and barrier to organic wine consumption. Based on literature studies, consumers have positive opinions toward organic wine, which is perceived as healthy and environmental friendly. However, despite the growing market interest in wine, scientific information about the organoleptic differences between conventional and organic remains scarce and the topic requires more in-depth analysis. Understanding the profile of consumer and the factors that influence consumer' behaviour provide information to the organic wine industry

    The role of credence attributes in consumer choices of sustainable fish products: A review

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    This review aims to assess consumer choices of sustainable fish products, considering a number of attributes that have been considered in the academic literature on this topic. In order to examine the effectiveness of sustainable labels, the research question was focused on the relation between sustainable fish labels and consumers’ willingness to pay (WTP). The findings showed how, overall, consumers have positive perceptions regarding sustainable fish products and show a willingness to pay a premium price for the attribute of sustainability. According to the results, the country of origin attribute was found to be the most important attribute in relation to consumer choice. The results indicated a high WTP for local fish products, relative to imported alternatives. Consumers prefer wild-caught fish for its perceived quality, better safety and health aspects, and taste perception than the farm-raised option. As for animal welfare, the results show that consumers are willing to pay a moderate premium price for products that have an improved fish welfare or those that avoid by-catch, such as products with eco-labels like “turtle safe”. With regard to organic labels, the studies identified a positive organic price premium for fish products. However, organic labels do not play a major role in consumer choice, when compared with other attributes

    Trends in consumers’ preferences towards fresh-cut vegetables during the Covid-19 pandemic

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    The fresh-cut sector has shown a positive trend in recent years, due to the “ease of use” and the increasing innovation in the quality and safety features of these products. However, in Italy, a negative trend was observed during the lockdown Covid-19. The objective of this study is to investigate consumer preferences for fresh-cut products and to identify the sensory and extrinsic attributes that influence consumer choice. It also examines whether consumer behaviour has changed during the lockdown Covid-19. An online questionnaire was administered to a convenience sample of 427 consumers. A one-way ANOVA was conducted to identify preferences for specific types of fresh-cut products; then, a factor analysis was conducted to highlight key socioeconomic variables and product attributes. Finally, a cluster analysis was conducted to identify homogeneous consumer groups. The results indicate that some attributes, including “ease of use”, “texture” and “colour” show a high level of interest and appreciation by consumers. The outcomes also reveal that there has been a change in consumer attitudes during the lockdown Covid-19, mainly for reasons related to the difficulty in food procurement, the fear of contagion during purchasing occasion, and higher prices. The findings of this research contribute to the knowledge of consumers’ behaviour towards fresh-cut products in the period of lockdown Covid-19
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