908 resultados para Twin Paradox
Resumo:
Selleri's arguments that a consideration of noninertial reference frames in the framework of special relativity identify absolute simultaneity as being Nature's choice of synchronization are considered. In the case of rectilinearly accelerating rockets, it is argued by considering two rockets which maintain a fixed proper separation rather than a fixed separation relative to the inertial frame in which they start from rest, that what seems the most natural choice for a simultaneity convention is problem-dependent and that Einstein's definition is the most natural (though still conventional) choice in this case. In addition, the supposed problems special relativity has with treating a rotating disk, namely how a pulse of light traveling around the circumference of the disk can have a local speed of light equal to c everywhere but a global speed not equal to c, and how coordinate transformations to the disk can give the Lorentz transformations in the limit of large disk radius but small angular velocity, are addressed. It is shown that the theory of Fermi frames solves both of these problems. It is also argued that the question of defining simultaneity relative to a uniformly rotating disk does riot need to be resolved in order to resolve Ehrenfest's paradox.
Resumo:
Migraine is a painful disorder for which the etiology remains obscure. Diagnosis is largely based on International Headache Society criteria. However, no feature occurs in all patients who meet these criteria, and no single symptom is required for diagnosis. Consequently, this definition may not accurately reflect the phenotypic heterogeneity or genetic basis of the disorder. Such phenotypic uncertainty is typical for complex genetic disorders and has encouraged interest in multivariate statistical methods for classifying disease phenotypes. We applied three popular statistical phenotyping methods—latent class analysis, grade of membership and grade of membership “fuzzy” clustering (Fanny)—to migraine symptom data, and compared heritability and genome-wide linkage results obtained using each approach. Our results demonstrate that different methodologies produce different clustering structures and non-negligible differences in subsequent analyses. We therefore urge caution in the use of any single approach and suggest that multiple phenotyping methods be used.
Resumo:
As the ultimate corporate decision-makers, directors have an impact on the investment time horizons of the corporations they govern. How they make investment decisions has been profoundly influenced by the expansion of the investment chain and the increasing concentration of share ownership in institutional hands. By examining agency in light of legal theory, we highlight that the board is in fact sui generis and not an agent of shareholders. Consequently, transparency can lead to directors being 'captured' by institutional investor objectives and timeframes, potentially to the detriment of the corporation as a whole. The counter-intuitive conclusion is that transparency may, under certain conditions, undermine good corporate governance and lead to excessive short-termism.
Relative income, happiness, and utility : an explanation for the Easterlin paradox and other puzzles
Resumo:
The well-known Easterlin paradox points out that average happiness has remained constant over time despite sharp rises in GNP per head. At the same time, a micro literature has typically found positive correlations between individual income and individual measures of subjective well-being. This paper suggests that these two findings are consistent with the presence of relative income terms in the utility function. Income may be evaluated relative to others (social comparison) or to oneself in the past (habituation). We review the evidence on relative income from the subjective well-being literature. We also discuss the relation (or not) between happiness and utility, and discuss some nonhappiness research (behavioral, experimental, neurological) related to income comparisons. We last consider how relative income in the utility function can affect economic models of behavior in the domains of consumption, investment, economic growth, savings, taxation, labor supply, wages, and migration.
Resumo:
This paper reports on a study investigating preferred driving speeds and frequency of speeding of 320 Queensland drivers. Despite growing community concern about speeding and extensive research linking it to road trauma, speeding remains a pervasive, and arguably, socially acceptable behaviour. This presents an apparent paradox regarding the mismatch between beliefs and behaviours, and highlights the necessity to better understand the factors contributing to speeding. Utilising self-reported behaviour and attitudinal measures, results of this study support the notion of a speed paradox. Two thirds of participants agreed that exceeding the limit is not worth the risks nor is it okay to exceed the posted limit. Despite this, more than half (58.4%) of the participants reported a preference to exceed the 100km/hour speed limit, with one third preferring to do so by 10 to 20 km/hour. Further, mean preferred driving speeds on both urban and open roads suggest a perceived enforcement tolerance of 10%, suggesting that posted limits have limited direct influence on speed choice. Factors that significantly predicted the frequency of speeding included: exposure to role models who speed; favourable attitudes to speeding; experiences of punishment avoidance; and the perceived certainty of punishment for speeding. These findings have important policy implications, particularly relating to the use of enforcement tolerances.
Resumo:
the (dis)orientation of thought in its encounter with art can be understood as the direct result of an encounter with indeterminacy as a lack in meaning. As an artist I am aware of how this indeterminacy impacts on the perceived value and authority of the artistic voice and in particular its value as a research voice. This paper explores this indeterminacy of meaning, as a profound and disturbing unknowing characteristic of the sublime and argues its value to advanced thought and for any methodological understanding of practice-led research. Lyotard described the sublime as an ‘understanding’ through which art and its associated practices may be able to resist an all too easy assimilation by the public as just a consumer commodity. His thought represents an attempt to both politically and philosophically understand art’s, and particularly abstract painting’s, affect as a state of profound and positive unknowing. To talk of the sublime in art is to speak of the suspension of any comfortable certainty in being and instead to engage with the real as a limit to meaning and knowing. It is to talk of the presentation of the unpresentable as a momentary but significant dissolution of representation. This understanding of the sublime is then further explored through the cultural phenomena of the monochrome painting and applied to the work of the two contemporary artists, Franz Erhard Walter and Günter Umberg. Initially the monochrome was understood as an attempt to go beyond traditional representation and present the unpresentable. In the one hundred years or so since that initial move this understanding has broadened. The monochrome now presents itself as a genre or even project within visual art but it still has much to teach us. In the concretely abstract and performative artworks of Franz Erhard Walter and Günter Umberg, traces of this ambition remain and their work can be seen to pose questions probing our understandings and experiences of artistic meaning, its value and the real.
Resumo:
Effective staff development remains a challenge in higher education. This paper examines the non-traditional methodology of arts-based staff development, its potential to foster transformational learning and the practice of professional artistry, through perceptions of program impact. Over a three year period, eighty academics participated in one metropolitan Australian university’s arts-based academic development program. The methodology used one-on-one hermeneutic-based conversations with fifteen self-selected academics and a focus group with twenty other academics from all three years. The paper presents a learning model to engender academic professional artistry. The findings provide developers with support for using a non-traditional strategy of transformational learning.
Resumo:
Managing project-based learning is becoming an increasingly important part of project management. This article presents a comparative case study of 12 cases of knowledge transfer between temporary inter-organizational projects and permanent parent organizations. Our set-theoretic analysis of these data yields two major findings. First, a high level of absorptive capacity of the project owner is a necessary condition for successful project knowledge transfer, which implies that the responsibility for knowledge transfer seems to in the first place lie with the project parent organization, not with the project manager. Second, none of the factors are sufficient by themselves. This implies that successful project knowledge transfer is a complex process always involving configurations of multiple factors. We link these implications with the view of projects as complex temporary organizational forms in which successful project managers need to cope with complexity by simultaneously paying attention to both relational and organizational processes.
Resumo:
This article continues the critical analysis of ‘meaningful relationships’ in the context of the operation of the ‘twin pillars’ which underpin the parenting provisions. It will be argued that the attitude of judicial officers to three key questions influence how they interpret this concept and consequently apply the best interest considerations. Relevant to this discussion is an examination of the Full Court’s approach to the key parenting sections, particularly the interaction of the primary and additional considerations. Against this backdrop, a current proposal to amend the ‘twin pillars’ will be examined.
Resumo:
Discusses the role of the family in the development, treatment and prevention of adolescent depression. Studies have demonstrated that between 21–32% of adolescents report mild to severe symptoms of depression. The research points out the need for increased attention to adolescent depression because of its high prevalence, the risk factor for the development of other disorders and suicide, recurrence and tendency to endure into adulthood. Many studies have shown a strong relationship between depressive symptomatology and family factors. Therefore, family interventions should play an important role in the prevention and treatment of adolescent depression. However, there exists a paradox in that the research published to date fails to show that family-intervention programs add to the efficacy of treatments provided to the adolescents. Possible explanations for this paradox are discussed.