碰摩转子系统分叉与混沌行为的识别

研究了Jeffcott转子发生动静件碰摩时的非线性振动特性.根据数值计算的结果,利用时间序列的相空间重构方法,通过相空间的吸引子的形态来刻画碰摩转子系统的分叉、拟周期和混沌行为,利用分形维数对分叉、拟周期和混沌信号进行定性的分析.这对定性和定量的判定系统的分叉、拟周期和混沌行为是一个非常有意义.     

Toxoplasmosis in families. II. Clinical analysis

Asthma is characterized histologically by a bronchial subepithelial fibrosis. Cytokines and other mediators released in the asthmatic chronic inflammatory microenvironment can activate the repair process that leads to fibroblast proliferation and collagen synthesis. To our knowledge, there are no data regarding the effect of a chronic inflammatory microenvironment on the phenotype of human bronchial fibroblasts. In the present study, we address this issue by comparing bronchial fibroblasts isolated from normal and asthmatic subjects in terms of: (a) proliferation over cell passage; (b) in vitro lifespan; (c) proliferative response to transforming growth factor-beta 1, platelet-derived growth factor-BB, dexamethasone, and retinoic acid; and (d) base-line synthesis of procollagens I and III. Bronchial fibroblasts from asthmatic subjects demonstrated lower DNA synthesis with cell passage than bronchial fibroblasts from normals. The in vitro lifespan of asthmatic bronchial fibroblasts was lower than in those from normal subjects and was significantly correlated with airway responsiveness. Platelet-derived growth factor-BB and dexamethasone increased 3H-thymidine incorporation in asthmatic bronchial fibroblasts without having any significant effect on normal fibroblast proliferation. Transforming growth factor-beta 1 and retinoic acid had no significant effect on bronchial fibroblast proliferation. Base-line procollagens I and III synthesis measurements showed no differences between normal and asthmatic fibroblasts. Taken together, these results indicate that the chronic inflammatory microenvironment found in asthma can modulate some aspects of bronchial fibroblast phenotype.     

Melnikov analysis of chaos in a simple epidemiological model

Factors limiting binocular fusion were studied using 2-dimensional difference of Gaussian (2D-DOG) stimuli. The proportion of fused stimuli and observer's response time were determined for stimuli that varied in spatial frequency composition between 0.22 and 4.8 cycles per degree. At small disparities, mean fusion response times were short and relatively stable but increased rapidly once the disparity reached a certain critical value. This 2-phase function implies the existence of 2 separate fusional mechanisms: a rapid neurally based fusional process, which operates at small disparities, and a second mechanism involving reflexive vergence movements operating at disparities 2 to 3 times larger. Both mechanisms are highly influenced by spatial frequency, being 4 to 5 times more effective at low spatial frequencies. Additional experiments demonstrated that with compound stimuli, the fusion limit is not determined by the highest spatial frequency components (as had been reported previously) but, rather, can take advantage of the additional fusional range associated with low spatial frequencies. Such cooperation may be obvious only in the case of 2-dimensional stimuli.     

Psychotherapy and chaos theory: The metaphoric relationship between psychodynamic therapy and chaos theory.

Explored potential benefits and problems in applying chaos theory in psychotherapy through an examination of previous attempts to integrate chaos theory in psychoanalysis and psychodynamic therapy. First, a discussion provides an understanding of basic concepts in chaos theory and reviews applications in psychoanalysis. Second, problems in such application are scrutinized. Finally, the discussion speculates on a general tendency in the literature in psychotherapy and counseling to resort to mathematical analogies, arguing that this attraction may produce an "erroneous metaphor," and gives reasons both for the attraction and its danger. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dopamine and preparatory behavior: II. A neurochemical analysis.

Changes in the activity of dopamine-containing systems in relation to preparatory and consummatory feeding responses were investigated. In Exp 1 rats were conditioned to associate food delivery with the presentation of a conditional stimulus (CS+). When sacrificed after exposure to the CS+ alone on a test trial, the ratio of the dopamine metabolite 3,4-dihydroxyphenylacetic acid to dopamine ({dopac/da} ratio) was increased significantly in the nucleus accumbens. A similar trend in the ratio of homovanillic acid to dopamine ({hva/da} ratio) was also observed. Similar increases were observed in the striatum, but these were not statistically significant. In contrast, no increases were observed in the {dopac/da} ratio or the {hva/da} ratio in either brain region when rats were permitted to consume an unsignaled meal for 7 min. Findings suggest that activation of dopamine terminals in the nucleus accumbens occurs during the anticipation of a meal, at which times the rat is engaged in preparatory feeding behaviors, but does not accompany the performance of short bouts of consummatory feeding behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rapid eye movements in myasthenia gravis. II. Electro-oculographic analysis

Voluntary saccades were studied by electro-oculography in ten patients with myasthenia gravis (MG) and in eight patients with other types of ophthalmoplegia. Despite limited range of eye movements, maximum velocities of 20 degree and 40 degree saccades in patients with MG were not significantly different from those in normal individuals, whereas maximum velocities in patients with other types of ophthalmoplegia were significantly decreased. In some myasthenic patients, small amplitude saccades were hypermetric and had high velocities, appearing clinically as "quiver" movements characteristic of MG. In MG the preservation of saccades with high initial velocities, even in the presence of severe ophthalmoplegia, suggests that muscle fibers generating rapid movements during saccades (twitch fibers) can be relatively spared when muscle fibers responsible for maintenance of excentric gaze (tonic fibers) are severely affected.