57 resultados para Conformal invariance


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The definition of semi-hyperbolic dynamical systems generated by Lipschitz continuous and not necessarily invertible mappings in Banach spaces is presented in this thesis. Like hyperbolic mappings, they involve a splitting into stable and unstable spaces, but a slight leakage from the strict invariance of the spaces is possible and the unstable subspaces are assumed to be finite dimensional. Bi-shadowing is a combination of the concepts of shadowing and inverse shadowing and is usually used to compare pseudo-trajectories calculated by a computer with the true trajectories. In this thesis, the concept of bi-shadowing in a Banach space is defined and proved for semi-hyperbolic dynamical systems generated by Lipschitz mappings. As an application to the concept of bishadowing, linear delay differential equations are shown to be bi-shadowing with respect to pseudo-trajectories generated by nonlinear small perturbations of the linear delay equation. This shows robustness of solutions of the linear delay equation with respect to small nonlinear perturbations. Complicated dynamical behaviour is often a consequence of the expansivity of a dynamical system. Semi-hyperbolic dynamical systems generated by Lipschitz mappings on a Banach space are shown to be exponentially expansive, and explicit rates of expansion are determined. The result is applied to a nonsmooth noninvertible system generated by delay differential equation. It is shown that semi-hyperbolic mappings are locally φ-contracting, where -0 is the Hausdorff measure of noncompactness, and that a linear operator is semi-hyperbolic if and only if it is φ-contracting and has no spectral values on the unit circle. The definition of φ-bi-shadowing is given and it is shown that semi-hyperbolic mappings in Banach spaces are φ-bi-shadowing with respect to locally condensing continuous comparison mappings. The result is applied to linear delay differential equations of neutral type with nonsmooth perturbations. Finally, it is shown that a small delay perturbation of an ordinary differential equation with a homoclinic trajectory is ‘chaotic’.

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Focussing on humaniod monsters, this thesis uses insights from Foucault's theory about the "archaeology" of discourses and Derrida's practice of deconstruction to examine how monstrosity was spoken of in antiquity, and how the various "sciences" dealt with anomalous monsters without jeopardising their epistemological credibility. Discussion begins with a survey of the semantic field of teras and monstrum. Since portentousness was central to both terms, the signification of monstrous portents in divinatory practice is next aalysed in the historiography of Herodotus, Livy, and others. Cicero's De divinatione reveals the theory and the problem for that science posed by accidental monstrosities. Chance and novelty are also issues in mythical and scientific cosmogonies < of Hesiod, and Orphism, Empedo-cles, and Lucretius> , where monsters arise and are dealt with while cosmic regularities, reproductive and ethical, are being established. Teleology and the stability of species'forms emerge as important concerns. These issues are further considered in Aristotle's bioogy and in medical writings from Hippocrates to Galen. There, theories are produced about monstrous embryology which attempt to answer the question of how deformities occur if species' forms are perpetuated through repro-duction. Biological and taxonomic--as well as ethical--boundaries are violated also by mythic human-beast hybrids. Narratives about such anomalies clarify the nature of monstrous deviance and enact solutions to the problem. Their strategies have much in common with other modes of discourse. Ethnography is posed similar questions about monstrous races' physical and ethical deviations from the civilised norm; it speaks of those issues in terms of invariance of form through generations, geographical remoteness and the codes which situate those races ethically. Finally, Augustine’s discourse on monstrous individuals and races is examined as Christianity’s belief in God’s governance reformulates the ancient’s discussions of chane or novelty and the invariance of species. In all these discourses founded on determinate meaning, the persistant paradox of monstrosity need offer no challenge to rationality provided its indefinable diversity is unacknowledged and the notion is constructed in such a way as to reaffirm the certainties.

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The oldest and best-known cooperative bargaining solution concept is the Nash solution. Nash [2] characterized his seminal solution concept by using the axioms of ‘Independence of Irrelevant Alternatives’ (IIA), ‘Weak Pareto Optimality’ (WPO), ‘Symmetry’ (SYM), and ‘Scale Invariance’ (SI). Except for WPO, these axioms have been at the center of controversy (especially the most crucial axiom, IIA). This paper considers a new and simple axiom ‘Focal Relevance of a Pareto-optimal Midpoint’ (FRPM). It turns out that the Nash solution can be characterized by WPO and FRPM only.

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This project was concerned with the perception of size constancy of simple, elongated and planar objects in the light and dark. The main findings are: transverse, vertical and medial axes give rise to different degrees of size constancy; true size and shape of the objects proved to be a factor in size constancy; the size-distance invariance hypothesis (SDIH) cannot explain underconstancy in the light, and perfect constancy in the dark.

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A useful understanding of the relationship between age, actuarial scores, and sexual recidivism can be obtained by comparing the entries in equivalent cells from “agestratified” actuarial tables. This article reports the compilation of the first multisample age-stratified table of sexual recidivism rates, referred to as the “multisample age-stratified table of sexual recidivism rates (MATS-1),” from recent research on Static-99 and another actuarial known as the Automated Sexual Recidivism Scale. The MATS-1 validates the “age invariance effect” that the risk of sexual recidivism declines with advancing age and shows that age-restricted tables underestimate risk for younger offenders and overestimate risk for older offenders. Based on data from more than 9,000 sex offenders, our conclusion is that evaluators should report recidivism estimates from age-stratified tables when they are assessing sexual recidivism risk, particularly when evaluating the aging sex offender.

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The importance of a positive self-concept as an educational outcome and a facilitator of other desirable outcomes are well established within the education research field. Although the multidimensional and hierarchical model of the self-concept is widely accepted within the educational psychology, this perspective is not widely used within the mental health research. Hence, the purpose of the present investigation is to compare the psychometric properties of the short version of the Self-Description Questionnaire (SDQII-S) based on responses by a large sample of female adolescent high school students (N= 829) and a clinical sample of adolescent girls who have been diagnosed with anorexia nervosa (N= 75). The well-established psychometric properties of the longer version of the SDQII generalise well to both samples of adolescent girls, and analyses provided good support for the invariance of the factor structure across the two samples. Furthermore, analyses employing new structural equation modelling approaches to comparing the latent mean differences indicated that there were differences (although surprisingly small) between the two groups that were generally consistent with a priori predictions. The important educational and clinical implications of these results are discussed.

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This empirical research of tourists’ cultural experiences aims to advance theory by developing a measurement model of attitudes towards attending cultural experiences for a sample of international tourists visiting Melbourne, Australia. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to cross-validate the underlying dimensionality structure of cultural experience attitudes in the model. A five-factor model was extracted from the EFA and some further modifications were required to establish discriminant validity. A four-factor model was retained in the CFA, which included three factors based on a liking for different types of cultural experiences and one factor indicating that social interaction was the most liked socio-psychological attitude towards attending cultural experiences. Although the sample were all English-speaking international tourists, cross-cultural validation of the model was also examined for factor configural and metric invariance of the measurement model as there were three different groups of international tourists within the sample: North Americans; New Zealanders; and tourists from United Kingdom and Ireland. This measurement structure was found to be relatively invariant for the factor loadings across the three groups of international tourists.

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This empirical research of tourists’ cultural experiences aims to advance theory by developing a measurement model of tourists’ motives towards attending cultural experiences for samples of Western and Asian tourists visiting Melbourne, Australia. Drawing upon Iso-Ahola’s (1989) seeking/avoiding dichotomy theory for tourist motivation dimensions, the hypothesized dimensions primarily included escape and seeking-related dimensions, and some hedonic dimensions because of their relevance to aesthetic products (Hirschman & Holbrook, 1982; Holbrook & Hirschman, 1982), which are the context for this study. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to crossvalidate the underlying dimensionality structure of cultural experience motives. A four-factor model was extracted from the EFA consistent with some theoretical formulations and was retained in the CFA. Specific cultural language group differences for the motive dimensions were also hypothesized between Western and Asian tourist samples, and within the Chinese- and Japanese-speaking Asian tourist samples, but not within the different cultural groups of English-speaking Western tourists. These cross-cultural hypotheses were tested for the motive dimension measurement model using invariance testing in CFA. The findings for the motive dimensions differing by cultural group were not as expected. Significant cultural differences between Western and Asian tourists were not found, but a new finding of this study was significant differences between English-speaking tourists in their motives for attending cultural experiences. Marketing implications of these findings are also presented.

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We propose a new axiom, weakest collective rationality (WCR) which is weaker than both weak Pareto optimality (WPO) in Nash’s (Econometrica 18:155–162, 1950) original characterization and strong individual rationality (SIR) in Roth’s (Math Oper Res 2:64–65, 1977) characterization of the Nash bargaining solution. We then characterize the Nash solution by symmetry (SYM), scale invariance (SI), independence of irrelevant alternatives (IIA) and our weakest collective rationality (WCR) axiom.

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Suppes-Sen dominance or SS-proofness (SSP) is a commonly accepted criterion of impartiality in distributive justice. Mariotti (Review of Economic Studies, 66, 733–741, 1999) characterized the Nash bargaining solution using Nash’s (Econometrica, 18, 155–162, 1950) scale invariance (SI) axiom and SSP. In this article, we introduce equity dominance (E-dominance). Using the intersection of SS-dominance and E-dominance requirements, we obtain a weaker version of SSP (WSSP). In addition, we consider α − SSP, where α measures the degree of minimum acceptable inequity aversion; α − SSP is weaker than weak Pareto optimality (WPO) when α = 1. We then show that it is still possible to characterize the Nash solution using WSSP and SI only or using α -SSP, SI, and individual rationality (IR) only for any a Î [0,1)[01). Using the union of SS-dominance and E-dominance requirements, we obtain a stronger version of SSP (SSSP). It turns out that there is no bargaining solution that satisfies SSSP and SI, but the Egalitarian solution turns out to be the unique solution satisfying SSSP.

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Purpose
To compare the levels of risk and protective factors and the predictive influence of these factors on alcohol, tobacco, and cannabis use over a 12-month follow-up period in Washington State in the United States and in Victoria, Australia.

Method
The study involved a longitudinal school-based survey of students drawn as a two-stage cluster sample recruited through schools, and administered in the years 2002 and 2003 in both states. The study used statewide representative samples of students in the seventh and ninth grades (n = 3,876) in Washington State and Victoria.

Results
Washington State students, relative to Victorian students, had higher rates of cannabis use but lower rates of alcohol and tobacco use at time 1. Levels of risk and protective factors showed few but important differences that contribute to the explanation of differences in substance use; Washington State students, relative to Victorian students, reported higher religiosity (odds ratio, .96 vs. .79) and availability of handguns (odds ratio, 1.23 vs. 1.18), but less favorable peer, community, and parental attitudes to substance use. The associations with substance use at follow-up are generally comparable, but in many instances were weaker in Washington State.

Conclusions
Levels of risk and protective factors and their associations with substance use at follow-up were mostly similar in the two states. Further high-quality longitudinal studies to establish invariance in the relations between risk and protective factors and substance use in adolescence across diverse countries are warranted.

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It is known that the constant modulus (CM) property of the source signal can be exploited to blindly equalize time-invariant single-inputmultiple-output (SIMO) and finite-impulse-response (FIR) channels. However, the time-invariance assumption about the channel cannot be satisfied in several practical applications, e.g., mobile communication. In this paper, we show that, under some mild conditions, the CM criterion can be extended to the blind equalization of a time-varying channel that is described by the complex exponential basis expansion model (CE-BEM). Although several existing blind equalization methods that are based on the CE-BEM have to employ higher order statistics to estimate all nonzero channel pulsations, the CM-based method only needs to estimate one pulsation using second-order statistics, which yields better estimation results. It also relaxes the restriction on the source signal and is applicable to some classes of signals with which the existing methods cannot deal.

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This study examines the direct impact of three dimensions of the institutional environment on managerial attitudes toward the natural environment and the direct influence of the latter on the environmental sustainability orientation (ESO) of small firms. We contend that when the institutional environment is perceived by owner–managers as supportive of sound natural environment management practices, they are more likely to develop a positive attitude toward natural environment issues and concerns. Such owner–manager attitudes are likely to lead to a positive and proactive orientation of their firms toward environmental sustainability. The study uses survey data from 166 small manufacturing firms located in three Philippine cities. First, the study develops and tests the measurement models to examine the validity of the constructs representing the firm’s institutional environment, managerial attitudes toward the natural environment and the ESO of firms. Second, the study develops and tests the structural models examining the institutional environment–managerial attitudes–ESO linkages. Multi-sample invariance structural model analysis shows the mediating role of managerial attitudes in the institutional environment–ESO nexus. The findings show that ESO is a construct comprising three dimensions: knowledge of environmental issues, sustainable practices and commitment toward environmental sustainability. The cognitive, regulatory and normative elements of the institutional environment are strongly linked to positive managerial attitudes toward environmental sustainability, which in turn, positively influences the firm’s overall ESO. Managerial attitudes play a mediating role in the institutional environment–ESO linkages. The managerial, practical, research and policy implications of the research findings are discussed.

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Although several studies in social psychology suggest that male participants are more likely than female ones to engage in individuating behaviors, other studies have found no gender differences in willingness to perform individuating acts. This study posits that differences in findings across past investigations may be attributed to the chosen domain of individuating behavior. The content of the Individuation Scale (Maslach, Stapp, & Santee, 1985) is examined in terms of Bakan's (1966) agency‐communion theory to identify two types of individuating behaviors that are consistent with men's gender role orientations (i.e., eliciting conflict, leadership), one type of individuating behavior that is consistent with women's gender role orientations (i.e., personal disclosures), and a gender‐neutral type of individuation (i.e., performance). Responses to the scale are obtained from a sample of business school students (N = 273) and a more heterogeneous mail survey sample (N = 621). A sequence of measurement invariance tests of a 4‐factor correlated model of the individuation measure indicates a high degree of equivalence in the meaning of the measure across gender groups. Subsequent latent‐means structure analysis examines gender differences in willingness to perform the 4 types of individuation behaviors captured in the scale. In the student sample, there were no mean differences in willingness to perform any of the 4 types of individuating acts. However, in the mail survey sample, findings of mean differences supported hypotheses derived from agency‐communion theory: For men as compared with women, the latent means for leadership and eliciting conflict were higher and the latent mean for personal disclosure was lower.

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The latent structure of a 16-item mentoring function instrument was analyzed with the responses of 568 full-time employees. Features of the analyses included (a) assessment of the items' distributional properties (i.e., skewness and kurtosis); (b) assessment of the factor structure using the Satorra-Bentler scaled test statistic; and (c) evaluation of the instrument's invariance across sex. Confirmatory factor analyses using the scaled chi-square supported a two-factor oblique model that consisted of psychosocial and career-related mentoring functions. The invariance tests suggested that the structure was invariant across sex groups.