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Relative vs. Absolute Stability in Self-Control: A Meta-AnalysisJanuary 2013 (has links)
abstract: ABSTRACT Research on self-control theory (Gottfredson & Hirschi, 1990) consistently supports its' central proposition that low self-control significantly affects crime. The theory includes other predictions, which have received far less empirical scrutiny. Among these is the argument that self-control is developed early in childhood and that individual differences then persist over time. Gottfredson and Hirschi contend that once established by age ten, self-control remains relatively stable over one's life-course (stability postulate). To determine the empirical status of Gottfredson and Hirschi's "stability postulate," a meta-analysis on existing empirical studies was conducted. Results for this study support the contentions made by Gottfredson and Hirschi, however the inclusion of various moderating variables significantly influenced this relationship. Keywords: self-control, self-control stability, absolute stability, relative stability / Dissertation/Thesis / Appendix / M.S. Criminology and Criminal Justice 2013
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Stability of BDF-ADI DiscretizationsFelício dos Reis, João Miguel 17 August 2017 (has links)
We present new results on absolute stability for BDF-ADI (Backward differentiation formula Alternating Direction Implicit) methods applied to a linear advection and diffusion equations. Unconditional absolute stability of the BDF2-ADI method is proven for advection and diffusion separately, as well as to the BDF3-ADI method for the purely-diffusive case. Conditional absolute stability of the BDF4-ADI is also proven for the purely-diffusive case, and stability regions for BDF3-ADI and BDF4- ADI are given in terms of the PDE coefficients and numerical parameters. Lastly, numerical experiments are presented to support the theoretical results and conjectures. These experiments also suggest future work.
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O problema de Lurie e aplicações às redes neurais / The problem of Lurie and applications to neural networksPinheiro, Rafael Fernandes 12 March 2015 (has links)
Neste trabalho apresentamos um assunto que tem contribuído em diversas áreas, o conhecido Problemas de Lurie. Para exemplificar sua aplicabilidade estudamos a Rede Neural de Hopfield e a relacionamos com o problema. Alguns teoremas são apresentados e um dos resultados do Problema de Lurie é aplicado ao modelo de Hopfield. / In the present work we show some properties of the so called Luries type equation. We treat particularly the stability conditions problem, and show how this theory is applied in a Hopfield neural network.
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A new computational approach to the synthesis of fixed order controllersMalik, Waqar Ahmad 15 May 2009 (has links)
The research described in this dissertation deals with an open problem concerning
the synthesis of controllers of xed order and structure. This problem is encountered
in a variety of applications. Simply put, the problem may be put as the
determination of the set, S of controller parameter vectors, K = (k1; k2; : : : ; kl),
that render Hurwitz a family (indexed by F) of complex polynomials of the form
fP0(s; ) + Pl
i=1 Pi(s; )ki; 2 Fg, where the polynomials Pj(s; ); j = 0; : : : ; l
are given data. They are specied by the plant to be controlled, the structure of the
controller desired and the performance that the controllers are expected to achieve.
Simple examples indicate that the set S can be non-convex and even be disconnected.
While the determination of the non-emptiness of S is decidable and amenable
to methods such as the quantier elimination scheme, such methods have not been
computationally tractable and more importantly, do not provide a reasonable approximation
for the set of controllers. Practical applications require the construction of a
set of controllers that will enable a control engineer to check the satisfaction of performance
criteria that may not be mathematically well characterized. The transient
performance criteria often fall into this category. From the practical viewpoint of the construction of approximations for S, this
dissertation is dierent from earlier work in the literature on this problem. A novel
feature of the proposed algorithm is the exploitation of the interlacing property of
Hurwitz polynomials to provide arbitrarily tight outer and inner approximation to
S. The approximation is given in terms of the union of polyhedral sets which are
constructed systematically using the Hermite-Biehler theorem and the generalizations
of the Descartes' rule of signs.
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A new computational approach to the synthesis of fixed order controllersMalik, Waqar Ahmad 10 October 2008 (has links)
The research described in this dissertation deals with an open problem concerning
the synthesis of controllers of xed order and structure. This problem is encountered
in a variety of applications. Simply put, the problem may be put as the
determination of the set, S of controller parameter vectors, K = (k1; k2,...,kl),
that render Hurwitz a family (indexed by F) of complex polynomials of the form
{P0(s.a) + [summation]
i=1 Pi(s,a)ki, a [set membership] F}, where the polynomials Pj(s,a), j = 0,...,l
are given data. They are specied by the plant to be controlled, the structure of the
controller desired and the performance that the controllers are expected to achieve.
Simple examples indicate that the set S can be non-convex and even be disconnected.
While the determination of the non-emptiness of S is decidable and amenable
to methods such as the quantier elimination scheme, such methods have not been
computationally tractable and more importantly, do not provide a reasonable approximation
for the set of controllers. Practical applications require the construction of a
set of controllers that will enable a control engineer to check the satisfaction of performance
criteria that may not be mathematically well characterized. The transient
performance criteria often fall into this category. From the practical viewpoint of the construction of approximations for S, this
dissertation is dierent from earlier work in the literature on this problem. A novel
feature of the proposed algorithm is the exploitation of the interlacing property of
Hurwitz polynomials to provide arbitrarily tight outer and inner approximation to
S. The approximation is given in terms of the union of polyhedral sets which are
constructed systematically using the Hermite-Biehler theorem and the generalizations
of the Descartes' rule of signs.
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Developmental Trajectories of Self-Control: Assessing the Stability HypothesisRay, James Vance 01 January 2011 (has links)
A key proposition of Gottfredson and Hirschi's (1990) self-control theory is the stability hypothesis which suggests that an individual's level of self-control, once established between the ages of 8-10, is stable over the life course. Empirical results from examinations of the stability hypothesis have been mixed. Prior tests of the stability hypothesis have employed aggregate assessment methods (e.g., mean-level and correlational analyses). Such approaches fail to take into account the possibility that individual developmental pathways may differ. This study employs individual longitudinal data over a four year period for 3,249 7th to 10th grade subjects to assess the stability hypothesis using both traditional stability estimation techniques (e.g., ANOVAs and zero-order correlations), as well as heterogeneity assessment methods - semiparametric group-based trajectory modeling (SPGM). Multinomial logistic regression (MLOGIT) of theoretically and empirically relevant risk factors (i.e., parenting, parental criminality, deviant peers, bonds to school) was employed to distinguish between developmental trajectories. SPGM results suggest that self-control is stable for a majority of the sample; however, a sizeable portion of the sample evinced trajectories for which self-control was marked by considerable change. Specifically, 6 unique trajectories in the development of self-control were identified - two groups were identified with high stable trajectories of self-control and four groups were identified that had lower, less stable trajectories of self-control. Additionally, several risk factors differentiated these groups. The results indicate that those with lower, less stable trajectories have more deviant peer association, higher rates of parental criminality, less intense bonds to school, and lower levels of parenting. These results indicate that self control is not stable nor is it consistent across groups, leading to a rejection of Hirschi and Gottfredson's explanation.
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O problema de Lurie e aplicações às redes neurais / The problem of Lurie and applications to neural networksRafael Fernandes Pinheiro 12 March 2015 (has links)
Neste trabalho apresentamos um assunto que tem contribuído em diversas áreas, o conhecido Problemas de Lurie. Para exemplificar sua aplicabilidade estudamos a Rede Neural de Hopfield e a relacionamos com o problema. Alguns teoremas são apresentados e um dos resultados do Problema de Lurie é aplicado ao modelo de Hopfield. / In the present work we show some properties of the so called Luries type equation. We treat particularly the stability conditions problem, and show how this theory is applied in a Hopfield neural network.
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Stability and Trajectories of Early Supportive Environment and Adolescents' Depression and MasteryWu, Minwei 05 1900 (has links)
Previous studies highlighted the importance of parental support for development of mastery of control and depressive symptoms. These studies tended to examine one time wave and outcomes related to that period, forwarding an assumption parenting behaviours do not change as children age. Using the National Longitudinal Survey of Youth 1979-Children and Young Adults, this study filled the gap by examining children's supportive environment at three time points and determining how levels of support across these points impacted children's depression and mastery at 18 years of age. Relative stability of mothers' supportive parenting (i.e., encouragement of social maturity, warmth and affection, and physical punishment) at early childhood, middle childhood, and early adolescence was examined by Kendall's tau correlations. Encouragement of social maturity showed relative stability between early and middle childhood and middle childhood and early adolescence; warmth and affection showed relative stability between early and middle childhood, and physical punishment showed relative stability across all time points. Absolute stability was examined using hierarchical linear modelling and Wilcoxon signed-rank test. No instances were found. Latent class growth analysis identified different trajectories of supportive environment among participants and three groups were identified. Multiple regressions conducted to examine how different trajectories affect late adolescents' depression and mastery found children of mothers from the least supportive group had statistically significant higher level of depression and lower level of mastery of control at 18 years of age; children of mothers from the progressively and continuously supportive group had similarly positive results of depression and mastery.
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Manipulation Of History And Language In Three DystopiasErsoy, Duygu 01 October 2006 (has links) (PDF)
In this study, the manipulations of history and language in the dystopias of &ldquo / Nineteen Eighty-Four&rdquo / by George Orwell, &ldquo / We&rdquo / by Yevgeni Zamyatin and &ldquo / Brave New World&rdquo / by Aldous Huxley are examined. The principal aim of this investigation is to demonstrate that in these imaginary societies absolute stability is achieved through the manipulations of these two domains. The thesis argues that if the domains of history and language are not taken under control, they are to provide the subjects with the standard of comparisons which would enable them to realize that they are in fact dominated. However, once these domains are manipulated, they are transformed into the means of the dystopian rulers for mentally impoverishing people in a way that they would not be capable of conceiving the flaws within the system and therefore, would not attempt to challenge the order or require a change. In this sense, it is proposed that the subjects of these closed societies, who are formed as a result of the reshaping of history and language, would lack the mental capabilities to identify their subjection and behave automatically in the manner that is imposed on them by the political order.
Moreover, in this study, the relationship of the genre dystopia with political theory is explored / it is indicated that dystopias are not only literary works, but rather they are also texts of social criticism containing certain warnings about the future course of events. Relying on this argument, it is claimed that such an invasion of the minds by the control over history and language in our three dystopias is the exaggerated version of the ideological relationships of the individuals to these two realms in the contemporary societies. Thus, having in mind that in the dystopias examined here the manipulations of history and language are the preconditions of the use of other realms (such as religion, sexuality and science), it is concluded that these texts enable modern individuals to see that in order to maintain a critical distance with the established political and social order, the multiplicity of linguistic resources and knowledge of history are very crucial.
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Frequency domain analysis of feedback interconnections of stable systemsMaya Gonzalez, Martin January 2015 (has links)
The study of non-linear input-output maps can be summarized by three concepts: Gain, Positivity and Dissipativity. However, in order to make efficient use of these theorems it is necessary to use loop transformations and weightings, or so called ”multipliers”.The first problem this thesis studies is the feedback interconnection of a Linear Time Invariant system with a memoryless bounded and monotone non-linearity, or so called Absolute Stability problem, for which the test for stability is equivalent to show the existence of a Zames-Falb multiplier. The main advantage of this approach is that Zames–Falb multipliers can be specialized to recover important tools such as Circle criterion and the Popov criterion. Albeit Zames-Falb multipliers are an efficient way of describing non-linearities in frequency domain, the Fourier transform of the multiplier does not preserve the L1 norm. This problem has been addressed by two paradigms: mathematically complex multipliers with exact L1 norm and multipliers with mathematically tractable frequency domain properties but approximate L1 norm. However, this thesis exposes a third factor that leads to conservative results: causality of Zames-Falb multipliers. This thesis exposes the consequences of narrowing the search Zames-Falb multipliers to causal multipliers, and motivated by this argument, introduces an anticausal complementary method for the causal multiplier synthesis in [1].The second subject of this thesis is the feedback interconnection of two bounded systems. The interconnection of two arbitrary systems has been a well understood problem from the point of view of Dissipativity and Passivity. Nonetheless, frequency domain analysis is largely restricted for passive systems by the need of canonically factorizable multipliers, while Dissipativity mostly exploits constant multipliers. This thesis uses IQC to show the stability of the feedback interconnection of two non-linear systems by introducing an equivalent representation of the IQC Theorem, and then studies formally the conditions that the IQC multipliers need. The result of this analysis is then compared with Passivity and Dissipativity by a series of corollaries.
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