19 resultados para HYBRID MESONS


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We report a search for narrow resonances, produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0 GeV/c^2. The data, collected with the CDF~II detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630 pb$^{-1}$. We use the dimuon invariant mass distribution to set 90% upper credible limits of about 1% to the ratio of the production cross section times muonic branching fraction of possible narrow resonances to that of the $\Upsilon(1{\rm S})$ meson.

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Hybrid innovations, or new products that combine two existing product categories into one, are increasingly popular in today’s marketplace. Despite this proliferation, few studies address them. The purpose of this thesis is to examine consumer evaluation of hybrid innovations by focusing on consumer categorization of such innovations and on factors contributing positively and negatively to their evaluation. This issue is examined by means of three studies. The first study addresses the proportion of consumers categorizing hybrid products as single- versus dual-purpose, what contributes to such a categorization, what differences can be found between the two groups, and if categorization can and should be included in models of innovation adoption. The second study expands on the scope by including motivation as a predictor of consumer evaluation and examines two cognitive and affective factors and their differential impact on innovation evaluation. Finally, the third study examines the product comparisons single- versus dual-purpose categorization induce. These three essays together build up a broader understanding of hybrid innovation evaluation. The thesis uses theories from both psychology and marketing to examine the issues at hand. Conceptual combination and analogical learning theories from psychology are used to comprehend categorization and knowledge transfer. From marketing, consumer behavior and innovation adoption studies are addressed to better understand the link between categorization and product evaluation and the factors contributing to product evaluation. The main results of the current thesis are that (1) most consumers categorize hybrid products as single- and not as dual-purpose products, (2) consumers that categorize them as dual-purpose find them more attractive (3) motivation has a significant effect on consumer evaluation of innovations; cognitive factors promote an emphasis on product net benefits, whereas affective factors induce consumers to consider product meaning in the form of categorization and perceived product complexity, (4) categorization constrains subsequent product evaluation, and (5) categorization can and should be included to models of innovation adoption. Maria Sääksjärvi is associated with CERS, the Center for Relationship Marketing and Service Management at the Swedish School of Economics and Business Administration

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A dramatically different consumption pattern seems to be emerging among a vast group of consumers. This may mean that conventional consumer stereotypes and segmentation theory are becoming outdated. The so called hybrid consumers seem to increasingly opt for both premium and budget alternatives in various product and service categories while mid-priced alternatives are losing share in their consumption basket. Although this type of polarisation, or dispersion, is already recognized as an important change, hybrid behaviour is still largely under-researched. The present study aims to analyze the possible drivers of hybrid consumption and by identifying typical categories and situations of trading up versus trading down derive tentative characteristics of hybrid consumption for further research on the topic. A tentative pattern of hybrid consumption was identified, which relates trading up to high-involvement, discretional spending and trading down to low-involvement necessities. However, it was also found that hybrid consumption transcends product category boundaries and may thus be less straightforward than previously perhaps assumed. In addition, a purchase pattern continuum was developed, accounting for various degrees of hybrid consumption.

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Understanding the responses of species and ecosystems to human-induced global environmental change has become a high research priority. The main aim of this thesis was to investigate how certain environmental factors that relate to global change affect European aspen (Populus tremula), a keystone species in boreal forests, and hybrid aspen (P. tremula × P. tremuloides), cultivated in commercial plantations. The main points under consideration were the acclimatization potential of aspen through changes in leaf morphology, as well as effects on growth, leaf litter chemistry and decomposition. The thesis is based on two experiments, in which young aspen (< 1 year) were exposed either to an atmospheric pollutant [elevated ozone (O3)] or variable resource availability [water, nitrogen (N)]; and two field studies, in which mature trees (> 8 years) were growing in environments exposed to multiple environmental stress factors (roadside and urban environments). The field studies included litter decomposition experiments. The results show that young aspen, especially the native European aspen, was sensitive to O3 in terms of visible leaf injuries. Elevated O3 resulted in reduced biomass allocation to roots and accelerated leaf senescence, suggesting negative effects on growth in the long term. Water and N availability modified the frost hardening of young aspen: High N supply, especially when combined with drought, postponed the development of frost hardiness, which in turn may predispose trees to early autumn frosts. This effect was more pronounced in European aspen. The field studies showed that mature aspen acclimatized to roadside and urban environments by producing more xeromorphic leaves. Leaf morphology was also observed to vary in response to interannual climatic variation, which further indicates the ability of aspen for phenotypic plasticity. Intraspecific variation was found in several of the traits measured, although intraspecific differences in response to the abiotic factors examined were generally small throughout the studies. However, some differences between clones were found in sensitivity to O3 and the roadside environment. Aspen leaf litter decomposition was retarded in the roadside environment, but only initially. By contrast, decomposition was found to be faster in the urban than the rural environment throughout the study. The higher quality of urban litter (higher in N, lower in lignin and phenolics), as well as higher temperature, N deposition and humus pH at the urban site were factors likely to promote decay. The phenotypic plasticity combined with intraspecific variation found in the studies imply that aspen has potential for withstanding environmental changes, although some global change factors, such as rising O3 levels, may adversely affect its performance. The results also suggest that the multiple environmental changes taking place in urban areas which correspond closely with the main drivers of global change can modify ecosystem functioning by promoting litter decomposition, mediated partly by alterations in leaf litter quality.