Search results for "Stability"
showing 10 items of 3085 documents
Generalized singly-implicit Runge-Kutta methods with arbitrary knots
1985
The aim of this paper is to derive Butcher's generalization of singly-implicit methods without restrictions on the knots. Our analysis yields explicit computable expressions for the similarity transformations involved which allow the efficient implementation of the first phase of the method, i.e. the solution of the nonlinear equations. Furthermore, simple formulas for the second phase of the method, i.e. computation of the approximations at the next nodal point, are established. Finally, the matrix which governs the stability of the method is studied.
A proof of bistability for the dual futile cycle
2014
Abstract The multiple futile cycle is an important building block in networks of chemical reactions arising in molecular biology. A typical process which it describes is the addition of n phosphate groups to a protein. It can be modelled by a system of ordinary differential equations depending on parameters. The special case n = 2 is called the dual futile cycle. The main result of this paper is a proof that there are parameter values for which the system of ODE describing the dual futile cycle has two distinct stable stationary solutions. The proof is based on bifurcation theory and geometric singular perturbation theory. An important entity built of three coupled multiple futile cycles is…
RNAi mediated acute depletion of Retinoblastoma protein (pRb) promotes aneuploidy in human primary cells via micronuclei formation
2009
BACKGROUND: Changes in chromosome number or structure as well as supernumerary centrosomes and multipolar mitoses are commonly observed in human tumors. Thus, centrosome amplification and mitotic checkpoint dysfunctions are believed possible causes of chromosomal instability. The Retinoblastoma tumor suppressor (RB) participates in the regulation of synchrony between DNA synthesis and centrosome duplication and it is involved in transcription regulation of some mitotic genes. Primary human fibroblasts were transfected transiently with short interfering RNA (siRNA) specific for human pRb to investigate the effects of pRb acute loss on chromosomal stability. RESULTS: Acutely pRb-depleted fibr…
Post-Transcriptional Regulation of Human Inducible Nitric-Oxide Synthase Expression by the Jun N-terminal Kinase
2007
Human inducible nitric-oxide synthase (iNOS) expression is regulated both at transcriptional and post-transcriptional levels. In the present study, the effect of Jun N-terminal kinase (JNK) on human iNOS expression was investigated. In A549/8 human alveolar epithelial cells, both the inhibition of JNK by a pharmacological inhibitor anthra[1,9-cd]pyrazol-6(2H)-one1,9-pyrazoloanthrone (SP600125) and small interfering RNA (siRNA)-mediated down-regulation of JNK led to a reduction of iNOS mRNA and protein expression. iNOS promoter activity was not affected by these treatments. Hence, JNK seems to regulate iNOS expression through post-transcriptional mechanisms by stabilizing iNOS mRNA. Our labo…
Further results on H<inf>&#x221E;</inf> control of switched linear time-delay systems
2012
In this note, we study the problems of stability analysis and H ∞ controller synthesis of discrete-time switched systems with time-varying delay. The system under consideration is firstly transformed into an interconnection system. Based on the system transformation and the scaled small gain theorem, the asymptotic stability of the original system is examined via the version of the bounded realness of the transformed forward system. The aim of the proposed approach is to reduce conservatism, which is made possible by a precise approximation of the time-varying delay and the input-output approach. The proposed stability condition is demonstrated to be much less conservative than most existin…
Fuzzy filter design for discrete-time delayed systems with distributed probabilistic sensor faults
2013
In this paper, the problem of distributed fuzzy filter design has been solved for T-S fuzzy systems with time-varying delays and multiple probabilistic packet losses. Our attention is paid to designing the distributed fuzzy filters to guarantee the filtering error dynamic system to be mean-square asymptotically stable with an average ℋ∞ performance. Sufficient conditions for the obtained filtering error dynamic system are proposed by applying a comparison model and the scaled small gain theorem. Based on the measurements and estimates of the system states for each sensor and its neighbors, the solution of the parameters of the distributed fuzzy filters is characterized in terms of the feasi…
Does the Implicit Association Test for assessing anxiety measure trait and state variance?
2004
The stability of the Implicit Association Test for assessing anxiety (IAT‐Anxiety) is lower than its internal consistency, indicating that the IAT‐Anxiety measures both stable and occasion‐specific variance. This suggests that the IAT‐Anxiety may be not only a valid measure of trait anxiety but also one of state anxiety. To test this assumption, two studies were conducted in which state anxiety was experimentally induced by a public speaking task. However, both studies showed that the IAT‐Anxiety score did not change when a state of anxiety was induced. Thus, it seems that occasion‐specific factors other than variations in state anxiety lead to occasion‐specific variance in the IAT‐Anxiety…
Change, Reliability, and Stability in Self-perceptions in Early Adolescence: A Four-year Follow-up Study
1995
Changes in self-perceptions of fitness, appearance, and self-esteem among adolescents were assessed in a 4-year follow-up study. Both the changes in the mean levels across time (profile analysis), and the changes in the reliability and stability of individual differences (i.e. covariance stability as test-retest correlations) were examined. The subjects (64 boys, 49 girls) were 11 years old at the first annual measurement. Self-esteem was assessed using the Rosenberg Self-Esteem Scale, as well as self-assessment questionnaires specifically designed for this study to assess Perceived Fitness and Perceived Appearance. MANOVA-and Simplex-models were used in the analysis. Our results among the…
At‐risk children's causal inferences given emotional feedback and their understanding of the excuse‐giving process
1994
Italian male school children, ranging in age from 7 to 10 years, were identified as at‐risk children on the basis of self‐reports, teacher questionnaires, and peer nominations assessing aggression, emotional instability, and pro‐social behaviour. Together with a normal control sample, these children participated in two studies guided by attribtional theory. In Study 1, following teacher emotional feedback of anger or sympathy for failure, attributional inferences regarding low ability or lack of effort as the cause of that failure were rated. In Study 2, controllable and uncontrollable causes of a social transgression were given, and participants rated the anticipated anger of the ‘victim’…
I-states-as-objects-analysis (ISOA): Extensions of an approach to studying short-term developmental processes by analyzing typical patterns
2012
I-states-as-objects-analysis (ISOA) is a person-oriented methodology for studying short-term developmental stability and change in patterns of variable values. ISOA is based on longitudinal data with the same set of variables measured at all measurement occasions. A key concept is the i-state, defined as a person’s pattern of variable values at a specific time point. All i-states are first subjected to a classification analysis that results in a time-invariant classification characterized by a number of typical i-states. Each person is then characterized at each time point by the typical i-state he/she belongs to. Then the person’s sequences of typical i-states are analyzed with regard to …