867 resultados para Possibility-Theoretical Approach
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Radical cations of a heptathienoacene a,b-substituted with four n-decyl side groups (D4T7C+) form exceptionally stable p-dimer dications already at ambient temperature (Chem. Comm. 2011, 47, 12622). This extraordinary p-dimerization process is investigated here with a focus on the ultimate[D4T7C+]2 p-dimer dication and yet-unreported transitoryspecies formed during and after the oxidation. To this end, we use a joint experimental and theoretical approach that combines cyclic voltammetry, in situ spectrochemistry and spectroelectrochemistry, EPR spectroscopy, and DFT calculations. The impact of temperature, thienoacene concentration, and the nature and concentration of counteranions on the p-dimerization process is also investigated in detail. Two different transitory species were detected in the course of the one-electron oxidation: 1) a different transient conformation of the ultimate [D4T7C+]2 p-dimer dications, the stability of which is strongly affected by the applied experimental conditions, and 2) intermediate [D4T7]2C+ p-dimer radical cations formed prior to the fully oxidized [D4T7]2C+ p-dimer dications. Thus, this comprehensive work demonstrates the formation of peculiar supramolecular species of heptathienoacene radical cations, the stability, nature, and structure of which have been successfully analyzed. We therefore believe that this study leads to a deeper fundamental understanding of the mechanism of dimer formation between conjugated aromatic systems.
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This work reports theoretical and experimental studies on the first hyperpolarizability (beta) of aminophenols, evaluating the influence of the NH(2) group position relative to the OH group on the hyperpolarizability. A new extension of hyper-Rayleigh scattering technique using picosecond pulse trains was employed to obtain the experimental absolute values of (beta). The theoretical static beta(0) values were calculated using AMI method implemented in the AMPAC program. The theoretical and experimental data show a clear dependence between beta and the relative position of the electron donor (D) and acceptor (A) groups, presenting the 2-aminophenol the higher values. Moreover, calculations show excellent qualitative agreement between theoretical and experimental data, which are improved when the simulations considering the solvated molecule in a combination of discrete solvent molecules interacting with the solute and the application of continuous dielectric model. Besides, the study indicates that the experimental hyperpolarizabilities seem to be a property of the solute-solvation shell system. These facts have affirmed that the theoretical approach employed can be successfully used to foresee the variation in beta due to modifications in the D/A position. Moreover, a theoretical study of the ground state absorption is performed and compared with experimental data. (C) 2008 Elsevier B.V. All rights reserved.
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A high level theoretical approach is used to characterize for the first time a manifold of doublet and quartet A + S and Omega states correlating with the first two dissociation channels of an as yet experimentally unknown molecular species, SI, sulfur monoidide. A set of spectroscopic constants is determined, including vibrationally averaged spin-orbit coupling constants, vibrationally averaged dipole moments, and dissociation energies. The transition dipole moment function for the spin-forbidden transition a (4)Sigma -X (2)Pi, and the associated radiative lifetimes were also evaluated. Two possibilities to detect transitions experimentally and to derive spectroscopic constants are suggested. (C) 2011 Elsevier B. V. All rights reserved.
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Structural, vibrational, and energetic properties of new molecular species, HSI and HIS are investigated for the first time using a state-of-the-art theoretical approach. These molecules can be easily differentiated by their geometric parameters and vibrational spectra. HSI is much more stable, and a direct unimolecular isomerization is very unlikely. Kinetics estimates predict that only at low temperatures there is a possibility of isolating HIS. For HS-I, we estimate a bond dissociation energy of 46.25 kcal/mol, and a heat of formation at 298.15 K of 12.84 kcal/mol. For the H(2)S + I(2) -> HSI + HI reaction enthalpy, we found 8.40 kcal/ mol. (C) 2008 Elsevier B.V. All rights reserved.
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This paper presents a theoretical approach to analysing educational media using the concept of historical consciousness. The concept of historical consciousness is defined and operationalised and its relevance for analysis of historical media discussed. One aspect of the theoretical framework proposed is then applied in an analysis of a history textbook account. The analysis finds that while the framework may be applied in analysis of textbooks, its results regarding historical consciousness are tentative and in need of further investigation from the perspective of how its users perceive and appropriate the textbook account. Still, it is argued that the framework proposed may be useful since it specifies how a historical consciousness may be manifested and what methodological approaches that can be used when analysing it.
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Purpose – The purpose of this paper is to extend thinking on service recovery processes and satisfaction with service recovery, using multi-dimensional consumer outcomes. The objective of the work was to propose that satisfaction with service recovery should be based on customers' expectations of the recovery encounter, which would be shaped by their expectations of “non-failed” encounters.
Design/methodology/approach – The paper adopts a theoretical approach. Using the existing service recovery literature as well as the traditional services literature, the conceptual framework and associated research propositions are developed.
Findings – The proposed framework suggests that service recovery is a service encounter it its own right. The effectiveness of recovery encounters will be based on how encounters operate relative to customer expectations and experiences with regard to the recovery activity.
Research limitations/implications – The research propositions and proposed framework need further empirical investigation.
Practical implications – The proposed framework suggests that managing service recovery should be undertaken in a similar fashion to managing any service, and thus managers need to understand customers' recovery expectations. Organisations also need to consider how a recovery action impacts on a range of customer outcomes, as focusing on one aspect will not capture consumers' full set of behaviours.
Originality/value – The proposed model identifies that service recovery should be evaluated with regard to consumers' recovery expectations and satisfaction is not based on expectations with regard to non-failed encounters.
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A theoretical analysis is presented for the estimation of the number of contacts between fibers in random multilayer nanofibrous assemblies with arbitrary fiber diameter and orientation. The statistics of fiber contacts for single-layer nanofiber mats were considered first, and the equations were developed for three-dimensional multilayer nanofibrous assemblies by considering the superposition of the single-layer assemblies. Based on the theoretical approach presented here for multilayer nanofibrous networks, the network porosity, mean fiber diameter and a function of fiber aspect ratio contribute to a model to determine the average number of fiber contacts per unit fiber length in multilayer nanofibrous mats. The theory is studied parametrically and results compared with the work of a model presented by Samson. It is shown that the presented model compared to the existing models is more sensitive with the fiber diameter in the nano-scale. It is also believed that the presented theory for fiber-to-fiber contacts is more realistic and useful for further studies of multilayer nanofibrous assemblies.
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Trabalho experimental, CUJO objetivo e provar ser possivel uma aprendizagem de ma10r sensibilização da comunicação não-verbal, atraves de um curso ção de Comunicações não-verbais. ~ precedido de de interaabordagem teórica mostrando a importância da comunicação não-verbale_ de como a Educação precisa se ocupar desta area. Apresenta,. em seguida, sugestoes para a aplicação dos resultados na formação de professores e propoe futuras pesqu1sas a tir da ora realizada.
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The investigation about the body consciousness in school Physical Education had as main objective reporting a possibility of intervention, linking it directly to the contents of Physical Education and considering it as a crosscutting theme in this research. In this scope, we worked specifically with two contents of Physical Education - knowledge about the body and fights. During the study, we are going to discuss about teaching strategies for the themes of body awareness. To develop this work, we used the following study questions: how is treated the body consciousness in Physical Education and how it has been addressed in educational interventions? What are the difficulties found to the themes of body awareness on different issues of school Physical Education? How body awareness thematized in contents in Physical Education is received by the students and what are the attitudes demonstrated by them during the development of these lessons? Based from questions of study, we used the following methodological tools: participant observation, interviews, photographic records, debates, films, dramatizations and dynamics, which they were performed to stimulate students' critical thinking about their body and the other children s one. The research with ethnographic characteristics was conducted in two schools: one elementary school I, in Natal and one elementary school II, held in the municipality of the João Câmara, in the state of Rio Grande do Norte. We developed a structure in order that the three dimensions of contents conceptual, procedural and attitudinal were experienced by students. The work is structured in five chapters. At first, we made an introduction to justify the motivations that led us to write about body awareness at school. In the second chapter, we discussed reflection about the body and its possibilities of understanding, reflecting on the body and how this awareness was being treated in physical education classes at school. In the third chapter, dealing with the body awareness and dialogue with the Physical Education, we had made a theoretical approach, from authors such as CLARO (1988), NÓBREGA (2000), ARAGÃO (2004), MELO (2006), LORENZETTO and MATTHIESEN (2008) in order to situate the body consciousness and its relationship with physical education. In the fourth chapter, we talked about body awareness thematized in physical education contents: knowledge about the body and fights. We introduced the teaching experience developed in the school and we discussed with authors such as OLIVIER (2000), DARIDO AND RANGEL (2008), among others, about how was the reflection about the body leaving of these experiences. The fifth chapter was intended to closing remarks, in which we concluded that the body awareness, treated in physical education in school by sociocultural and historical aspects, it will contribute in building a man, a body and a society. Although the body consciousness is crafted in a few moments of Physical Education, based on the practices of body awareness or alternatives; in our proposal, we pointed out another perspective to work with body awareness, bringing its elements to permeate and pass through the contents of Physical Education. At work we can see a suggestion for that these experiences are carried out by other Physical Education professionals, obviously adapting the activities according to age and educational level of students
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Letras - IBILCE
Theoretical approaches to forensic entomology: I. Mathematical model of postfeeding larval dispersal
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An overall theoretical approach to model phenomena of interest for forensic entomology is advanced. Efforts are concentrated in identifying biological attributes at the individual, population and community of the arthropod fauna associated with decomposing human corpses and then incorporating these attributes into mathematical models. In particular in this paper a diffusion model of dispersal of post feeding larvae is described for blowflies, which are the most common insects associated with corpses.