2,889 research outputs found

    Z-dependent Barriers in Multifragmentation from Poissonian Reducibility and Thermal Scaling

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    We explore the natural limit of binomial reducibility in nuclear multifragmentation by constructing excitation functions for intermediate mass fragments (IMF) of a given element Z. The resulting multiplicity distributions for each window of transverse energy are Poissonian. Thermal scaling is observed in the linear Arrhenius plots made from the average multiplicity of each element. ``Emission barriers'' are extracted from the slopes of the Arrhenius plots and their possible origin is discussed.Comment: 15 pages including 4 .ps figures. Submitted to Phys. Rev. Letters. Also available at http://csa5.lbl.gov/moretto

    The ideal relativistic spinning gas: polarization and spectra

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    We study the physics of the ideal relativistic rotating gas at thermodynamical equilibrium and provide analytical expressions of the momentum spectra and polarization vector for the case of massive particles with spin 1/2 and 1. We show that the finite angular momentum J entails an anisotropy in momentum spectra, with particles emitted orthogonally to J having, on average, a larger momentum than along its direction. Unlike in the non-relativistic case, the proper polarization vector turns out not to be aligned with the total angular momentum with a non-trivial momentum dependence.Comment: Final published version. Minor corrections to formula

    A roadmap for sustainability assessment in the food supply chain

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    Purpose: To develop a roadmap of sustainability practices and assessment mechanisms to advance in the sustainable supply chain (SSC) performance assessment in the food supply chain. The analysis is grounded on the contingency and stakeholder theories. Design/methodology/approach: The study follows a multiple case study approach analyzing the sustainability practices implementation and assessment across different supply chain stages in the food industry in Italy. The set of cases comprises 12 companies in the fresh fruit and vegetables (FFV), and seven companies in the “Balsamic Vinegar of Modena” (BVM) supply chains. Findings: The sustainability practices and assessment in each company in both supply chains according to their objectives are identified. Different stakeholder pressures for sustainability implementation and assessment are analyzed. The contingency factors that foster sustainability assessment are outlined as well. Finally, the study develops a roadmap with five levels of progress considering the groups of practices implemented and the type of assessment applied. Practical implications: The roadmap is a decision-making tool for planning and monitoring progress on SSC performance along five possible levels of progress. While identifying the assessment mechanisms implemented for different kind of sustainability practices, companies can develop a strategy according to their aims and capabilities and stakeholder's expectations. Originality/value: The novelties in this study are threefold. First, the roadmap with five levels of progress. Second, investigating two different food supply chains that allowed for a broader view regarding sustainability practices and assessment. Third, the adoption of stakeholder and contingency theories in SSC studies

    Exploring supply chain finance along different supply chain stages: a case-based research in the agri-food industry

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    PurposeSince 2008's financial crisis, attention toward supply chain finance (SCF) has increased. However, most research investigates SCF considering single supply chain (SC) stages or buyer-supplier dyads and focuses on a single SCF solution. It is important to see how different solutions are adopted at different SC stages, by actors with different financing needs. This study aims to analyze SCF at different SC stages, to understand why different solutions are implemented at different SC stages and the contingency factors (regulation, SC stage, product category and size) influencing their adoption. Design/methodology/approachThe paper is based on multiple exploratory case studies in the Italian agri-food industry, considering firms distributed at different SC stages and adopting multiple SCF solutions. The paper exploits a contingent approach (Sousa and Voss, 2008) to analyze how contingent factors influence SCF adoption at different SC stages. FindingsFindings explain how and why different SC stages (producer, cooperative, processor and retailer) implement different SCF solutions (reverse factoring, dynamic discounting, inventory finance and Minibond), describing contingency variables' impact on their adoption. Originality/valueTo the best of the authors' knowledge, the research is original in its description of SCF at different SC stages, considering different SC actors' drivers and barriers, and questioning the importance of a coordinated approach in SCF adoption along an entire SC. Moreover, the paper adopts a contingent approach, contributing to SCF research, seldomly based on theoretical lenses

    Effect of the dispersion of the chromophore on the optical performances of polarizers from polyethylene and 5”-thio-(3-butyl)nonyl-2,2’:5’,2”-terthiophene

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    A new polyethylene-compatible terthiophene chromophore, 5"-thio-(3-butyl) nonyl-2,2':5',2"-terthiophene, with melting point lower than 0degreesC was prepared and used for linear polarizers based on ultra-high-molecular-weight polyethylene (UHMWPE). Differential scanning calorimetry and scanning electron microscopy indicate that the new chromophore is dispersed uniformly in films of UHMWPE obtained by casting from solution. The films show excellent dichroic properties (dichroic ratio 30) at rather low drawing ratio (approximate to20). Moreover, qualitative agreement is observed with the Ward pseudo-affine deformation schem

    Step-to-step reproducibility and asymmetry to study gait auto-optimization in healthy and cerebral palsied subjects

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    AbstractObjectiveThe purpose of our study was to compare plantar pressure asymmetry and step-to-step reproducibility in both able-bodied persons and two groups of hemiplegics. The relevance of the research was to determine the efficiency of asymmetry and reproducibility as indexes for diagnosis and rehabilitation processes.Material and methodThis study comprised 31 healthy young subjects and 20 young subjects suffering from cerebral palsy hemiplegia assigned to two groups of 10 subjects according to the severity of their musculoskeletal disorders. The peaks of plantar pressure and the time to peak pressure were recorded with an in-shoe measurement system. The intra-individual coefficient of variability was calculated to indicate the consistency of plantar pressure during walking and to define gait stability. The effect size was computed to quantify the asymmetry and measurements were conducted at eight footprint locations.ResultsResults indicated few differences in step-to-step reproducibility between the healthy group and the less spastic group while the most affected group showed a more asymmetrical and unstable gait.ConclusionFrom the concept of self-optimisation and depending on the neuromotor disorders the organism could make priorities based on pain, mobility, stability or energy expenditure to develop the best gait auto-optimisation

    Statistical Interpretation of Joint Multiplicity Distributions of Neutrons and Charged Particles

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    Experimental joint multiplicity distributions of neutrons and charged particles emitted in complex nuclear reactions provide an important test of theoretical models. The method is applied to test three different theoretical models of nuclear multi-fragmentation, two of which fail the test. The measurement of neutrons is decisive in distinguishing between the Berlin and Copenhagen models of nuclear multi-fragmentation and challenges the interpretation of pseudo- Arrhenius plots. Statistical-model evaporation calculations with GEMINI give a good reproduction first and second moments of the experimental multiplicity correlations.Comment: 12 pages, 3 figures Added GEMINI calculations of multiplicity correlations Added brief discussion of how neutron emission is treated in MMM

    Correlations in Nuclear Arrhenius-Type Plots

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    Arrhenius-type plots for multifragmentation process, defined as the transverse energy dependence of the single-fragment emission-probability, -ln(p_{b}) vs 1/sqrt(E_{t}), have been studied by examining the relationship of the parameters p_{b} and E_{t} to the intermediate-mass fragment multiplicity . The linearity of these plots reflects the correlation of the fragment multiplicity with the transverse energy. These plots may not provide thermal scaling information about fragment production as previously suggested.Comment: 12 pages, Latex, 3 Postscript figures include
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