Mass perturbation of a body segment: 1. Effects on segment dynamics

Investigators often use mass perturbation of body segments as an experimental paradigm to study movement coordination. To analyze the effect of mass perturbation on small-amplitude oscillations, the authors linearize the equation of motion of a single segment moving in a vertical plane and derive the effect of added mass on the undamped eigenfrequency, the relative damping, and the low-frequency control gain of the segment. Mass addition results in a decrease in both the relative damping and the low-frequency control gain; the undamped eigenfrequency increases for mass addition between the pivot point and R0 (where R0 is the length of a point mass pendulum whose undamped eigenfrequency is identical to that of the unperturbed segment), decreases for mass addition beyond R0, and remains unaffected for mass addition at R0. For a typical lower leg + foot segment, R0 is just proximal to the ankle joint. That location may explain the absence of an effect on oscillation frequency in studies in which mass has been added to the ankle. The authors' analysis provides a basis for a more effective application of mass perturbations in future experiments.     

Training analysis in the dutch society for psychoanalytic psychotherapy: A survey of attitudes and feasibility

SUMMARY

As is the case in many training courses in psychoanalytic psychotherapy, one of the training requirements of the Dutch Society for Psychoanalytical Psychotherapy (NVPP) is a training analysis, currently a minimum duration of 700 hours. During the last few years, this requirement has become somewhat controversial. Because the NVPP does not have information about the current interest in NVPP membership, the Board of the NVPP decided to do a survey. Of 995 psychiatrists, clinical psychologists and psychotherapists, who had recently completed their training, or were still in training, 623 filled in a questionnaire. Of those who are interested in the NVPP training, 39 per cent judged the training analysis as not feasible in terms of time, and 61 per cent in terms of money. Forms of personal treatment thought desirable for anyone who wishes to become a psychoanalytic psychotherapist at a specialist level are, in descending order, psychoanalytic psychotherapy (63%), psychoanalysis (39%), psychoanalytic group psychotherapy (25%), and psychoanalytic marital or family therapy (6%). Respondents who judge personal analysis as not feasible, also tend to judge psychoanalysis to be equivalent to other forms of psychoanalytic psychotherapy, whereas those who judge personal analysis as feasible, tend to think that personal analysis is essential for a psychoanalytic psychotherapist at the specialist level.