Influence of delayed muscle reflexes on spinal stability: Model-based predictions allow alternative interpretations of experimental data

Model-based calculations indicate that reflex delay and reflex gain are both important for spinal stability. Experimental results demonstrate that chronic low back pain is associated with delayed muscle reflex responses of trunk muscles. The aim of the present study was to analyze the influence of such time-delayed reflexes on the stability using a simple biomechanical model. Additionally, we compared the model-based predictions with experimental data from chronic low back pain patients and healthy controls using surface-electromyography. Linear stability methods were applied to the musculoskeletal model, which was extended with a time-delayed reflex model. Lateral external perturbations were simulated around equilibrium to investigate the effects of reflex delay and gain on the stability of the human lumbar spine. The model simulations predicted that increased reflex delays require a reduction of the reflex gain to avoid spinal instability. The experimental data support this dependence for the investigated abdominal muscles in chronic low back pain patients and healthy control subjects. Reflex time-delay and gain dependence showed that a delayed reflex latency could have relevant influence on spinal stability, if subjects do not adapt their reflex amplitudes. Based on the model and the experimental results, the relationship between muscle reflex response latency and the maximum of the reflex amplitude should be considered for evaluation of (patho) physiological data. We recommend that training procedures should focus on speeding up the delayed reflex response as well as on increasing the amplitude of these reflexes.     

Demographic,health-related and psychosocial predictors of changes in depressive symptoms and anxiety in late middle-aged and older persons with fall-related injuries

Research on anxiety and depression after fall-related injuries to the extremities and its pre-fall determinants is scarce. The present study sought to examine change between pre-fall and post-fall anxiety and depression and its (pre-fall) predictors. Data were obtained from 181 Dutch persons, aged 57 and older, who sustained fall-related injuries between 1993 and 1997. Demographic (e.g. socio-economic status), health-related (e.g. number of chronic conditions), and psychosocial (e.g. social support, neuroticism) factors were determined in 1993 (prior to the fall). Depressive symptoms and anxiety were determined prior to the fall, and two, five and twelve months after the fall. Taking into account pre-fall anxiety and depression, pre-fall neuroticism was the most consistent, independent predictor of adverse changes in anxiety and depression. Other factors, including severity of the fall and age were not related to changes in anxiety and depression. Our prospective findings may be interpreted as support for the importance of personality for mental health outcomes in persons who have sustained fall-related injuries.     

Cerebellar Creativity: Abstraction of Mental Movements

Encouraging students' interdisciplinary thinking may be a key element in facilitating their creativity. In this article, I describe a case report involving teaching styles and assignments designed to teach psychology from a more interdisciplinary perspective. I present examples illustrating how the arts and humanities can enrich psychology and vice versa, and I report students' responses to the interdisciplinary approach.     

I. Frege and the rise of analytic philosophy∗

Since the beginning of the ‘eighties of the present century, a circle of relatively young American sociologists who are followers of Jeffrey Alexander are making energetic and spectacular efforts to supply sociology with a uniform and comprehensive theoretical framework by continuing Talcott Parsons' lifework. The present article is an appreciation of Alexander's achievements in the justification of a general sociological theory (especially a theory of action and social order) while pointing to objections that can be raised against the character of his theory. A scrutiny of Alexander's metatheoretical deliberations and of his interpretations of sociological classics such as Marx, Durkheim, Weber, and Parsons reveals that Alexander's metatheoretical frame is not flexible enough to actually reconstruct the problem situation of the classics. Pointers are given toward a theory of action that is not subject to the antinomy of utilitarianism and normativism, so that it is more adequate and appropriate to the heritage of the sociological classics, both from a theoretical and an interpretative angle.     

Predicting premature termination within a randomized controlled trial for binge-eating patients

Understanding the dropout rates of efficacious forms of psychotherapy for patients with binge eating disorder (BED) is an unsolved problem within this increasing population. Up until now the role of psychotherapy process characteristics as predictors of premature termination has not been investigated in the BED literature. Within a randomized controlled trial (N=78) we investigated the degree to which early psychological process characteristics, such as components of the therapeutic relationship and the experiences of mastery and motivational clarification, predicted premature termination of treatment. We statistically controlled for the influences of covariates such as rapid response of treatment, treatment group, body mass index, Axis II disorder, and patients' preexisting generalized self-efficacy at baseline. Patients' postsession reports from Sessions 1 to 5 indicated that low self-esteem in-session experiences was a stable predictor of premature termination. Its predictive value persisted after controlling for the above-mentioned covariates. Exploratory analyses further revealed low self-esteem experiences, low global alliance, and low mastery and clarification experiences as predictors in those patients who explicitly specified discontentment with therapy as reason for premature termination. These results indicate that patients' self-esteem experiences may not be an epiphenomenon of their specific psychopathology but may represent general mechanisms on which remaining or withdrawing from psychotherapeutic treatment depends. Early psychotherapy process characteristics should therefore be considered in training and evaluation of psychotherapists carrying through BED treatments.     

Age and gender differences in morningness-eveningness during adolescence

Morningness-eveningness was assessed in a large sample of adolescents and young adults. Morningness decreased from 12 to 15 years, and then remained on a stable level until about 20 years, when a turn back to morningness occurred. Boys and men were on average more evening-oriented than were girls and women. In detail, significant differences existed at the ages of 16, 18, and 19 years. A quadratic function explained more variance than a linear regression. Composite Scale of Morningness scores are related to puberty scores in boys and girls, and when combining data (i.e., higher pubertal development was related to eveningness).     

Process arrangements for variety,retention, and selection

This article argues that process management aimed at introducing variety, retention, and selection into complex decision-making processes can make a substantial contribution to improving them. It also describes process arrangements for variety, retention, and selection. He received his Ph. D. in public administration at Erasmus University, Rotterdam. He is also program director at the Netherlands School of Public Administration and director of the TUD research program on multi actor systems. His research concerns networks and network-organizations, with a strong focus on governance and management issues in networks. He is the author on a number of internationally recognized books on these issues. His conceptual approach of these issues has been applied in research on the open source movement, frequency allocation, the design of policy instruments and mediation (e.g. interconnection disputes). He is program leader of the Bsik research program Next Generation Infrastructures. He holds the post of chair research within the faculty.     

莱布尼兹与技术

莱布尼兹不仅是哲学家、数学家,而且还在科学技术上拥有许多重要发明.特别是他所发明的二进制,是所有计算机技术的基础.因此,把莱布尼兹看作信息时代之父并不是没有道理的.本文阐述了莱布尼兹在他的科学技术发明中所体现的系统论思想、科学工具化思想和他关于机器的比喻.作者进一步提出,在科技高度发展的今天,人作为具有自由本质的存在者,必须对自己的行动和技术后果负有责任.我们必须追问技术带来的弊端,并给予技术哲学以应有的地位.