Die Entwicklung wissenschaftlich begründeter Leitlinien

Ohne Zusammenfassung     

A post-fission perspective of the discovery of nuclear fission

Why was nuclear fission discovered under the repressive conditions of the Third Reich and not in one of the other leading countries in science? The attempts to answer this question leads to the formulation of the hypothesis that under the very special constellation of the working relations between Hahn and Meitner, the forced emigration of Meitner was advantageous insofar as it emancipated Hahn from the physical guardianship of Meitner, and liberated his chemical competence. This was a prerequisite to recognizing the presence of Barium in the debris of Uranium decay. At the same time it liberated Meitner so that she could break with the old physicalconcepts of knowledge when accepting Hahn's chemical results, and find the correct interpretation of the experiment. Moreover, Hahn's and Strassmann's inner emigration which kept them away from participating in political activities and engagements, as well as their abstinence from competing in fashionable research (which was stimulated by the increasing political isolation of Germany) helped them to concentrate on their more restricted investigations following unfashionable lines of thinking and were among the favourable conditions for making their great discovery.Based in a contribution to an International Workshop on the Fiftieth Anniversary of the Discovery of Nuclear Fission, Institute of Advanced Studies, Berlin, March 1989.     

An investigation of the diagnostic processing of contradictory information

In three parallel experiments, subjects rated their impressions of hypothetical 20-year-old males described by means of single or combined personality trait adjectives on 36 bipolar (Semantic Differential) scales. These ratings were a) intercorrelated across the scales (Q-technique) and factor analyzed separately for each subject, and b) submitted to an analysis of variance separately for each scale. It was shown that 1) when contradictory adjectives were combined the major portion of the variance of judgments fell on dimensions independent of that which characterized the contradiction; 2) there were substantial inter-individual consistencies in the direction of the deviation from that dimension; and 3) the utility of a linear model for the prediction of judgments of combined adjectives increases with increases in the extent to which the subject experiences the combination as consistent. However, the utility of the linear model decreases considerably and consistently if the combined adjectives are experienced as non-consistent.     

Organization of and access to semantic memory in aphasia

Previous experiments with picture sorting and matching tasks have shown aphasics to give more deviant responses than controls when decisions require the identification of single features of concepts, whereas their responses are close to normal whenever decisions have to be based on the relative overlap of broad associative fields. The present experiment was designed to compare picture matching based on single features (property verification) with picture matching based on category membership (category verification). Fifty-five aphasics (14 amnesics, 18 Brocas, 13 Wernickes, 10 global aphasics) and 29 right-brain-damaged control patients served as subjects. Aphasics were poorer than right hemisphere controls on property as well as on category sortings, especially when the sorting criterion was not a dominant property of the object or when the object in question was not a typical member of the criterion category. Contrary to other studies, the "semantic distance" variable did not differentially affect Brocas as compared to Wernickes aphasics. Verbal labels denoting the sorting criterion and added to the picture presentation did not affect the performance of the right hemisphere controls but significantly improved that of the aphasics.     

Children of parents with unipolar depression: A controlled 1-year follow-up

An earlier cross-sectional study indicated that children's health and adjustment is at risk when their parents are depressed. Here, we report the associated longitudinal changes in children and families when parental depression either remits or continues. Comparisons are made among three groups established at a 1-year follow-up: previously depressed parents whose symptoms have remitted (N = 34 remitted parents), previously depressed parents who continue to be depressed (N = 23 nonremitted parents), and sociodemographically matched control families (N = 95). Although remitted parents and their family social environments improved, their children were still functioning more poorly than children of controls. Both the children and the families of nonremitted parents continued to function more poorly than controls. A social-environmental framework indicates that parents' functioning as well as family stressors and resources are concurrently and predictively linked to children's health.     

Effects of sex-role deviant lifestyles in otherwise normal persons on the perception of maladjustment

Subjects rated 12 stimulus persons (SPs) on maladjustment in several areas, and on the likelihood of requiring psychiatric help, in a person perception task. Half of the SPs were male and half female. Half of each were sex-role congruent and half sex-role deviant in terms of occupation, life styles, or interests, though normal in all other respects. Bias scores were constructed for subjects reflecting the extent to which each was influenced by sex-role deviance. Measures of gender stereotyping and sex-role ideology were also obtained. Results showed that sex-role deviant SPs were rated as significantly more maladjusted than congruent SPs and more likely to require psychiatric help. Sex-role deviance had a much greater effect on male than female SPs. Gender stereotyping and sex-role ideology showed only a moderate relationship, which suggests that these concepts should be distinguished. Measures of evaluative bias showed low to moderate relationships with sex-role ideology and very low correlations with gender stereotyping.This research is based on parts of a doctoral dissertation by the first author. It was supported by an Ontario Mental Health Foundation Research Studentship Award to the first author and by Canada Council Grant #S74-0707 to the second author.     

NT-3 facilitates hippocampal plasticity and learning and memory by regulating neurogenesis

In the adult brain, the expression of NT-3 is largely confined to the hippocampal dentate gyrus (DG), an area exhibiting significant neurogenesis. Using a conditional mutant line in which the NT-3 gene is deleted in the brain, we investigated the role of NT-3 in adult neurogenesis, hippocampal plasticity, and memory. Bromodeoxyuridine (BrdU)-labeling experiments demonstrated that differentiation, rather than proliferation, of the neuronal precursor cells (NPCs) was significantly impaired in DG lacking NT-3. Triple labeling for BrdU, the neuronal marker NeuN, and the glial marker GFAP indicated that NT-3 affects the number of newly differentiated neurons, but not glia, in DG. Field recordings revealed a selective impairment in long-term potentiation (LTP) in the lateral, but not medial perforant path-granule neuron synapses. In parallel, the NT-3 mutant mice exhibited deficits in spatial memory tasks. In addition to identifying a novel role for NT-3 in adult NPC differentiation in vivo, our study provides a potential link between neurogenesis, dentate LTP, and spatial memory.     

Memory self-efficacy predicts memory performance: results from a 6-year follow-up study

The purpose of this study was to examine the relationship between memory self-efficacy (MSE) and a 6-year follow-up assessment of memory functioning in a sample of Dutch older adults. MSE was assessed by a Dutch abridged version of the Metamemory in Adulthood questionnaire (MIA; R. A. Dixon, D. F. Hultsch, & C. Hertzog, 1988; C. Hertzog, D. F. Hultsch, & R. A. Dixon, 1989; R. W. H. M. Ponds & J. Jolles, 1996). The total MSE score predicted memory performance at 6 years, as measured by the Visual Verbal Learning Task (VVLT; N. Brand & J. Jolles, 1985). A separate analysis of the different MSE subscales indicated that the MIA Change score was the most salient domain-specific MSE predictor of subsequent memory performance after 6 years. An extreme groups analysis of the MIA Change score revealed a pattern of performance for those who perceived that their memory was worsening, performing less well on the 3 trials of the VVLT when these were readministered at the 6-year follow-up.     

Innovation across cultures: Connecting leadership,identification, and creative behavior in organizations

Innovation is considered essential for today's organizations to survive and thrive. Researchers have also stressed the importance of leadership as a driver of followers' innovative work behavior (FIB). Yet, despite a large amount of research, three areas remain understudied: (a) The relative importance of different forms of leadership for FIB; (b) the mechanisms through which leadership impacts FIB; and (c) the degree to which relationships between leadership and FIB are generalizable across cultures. To address these lacunae, we propose an integrated model connecting four types of positive leadership behaviors, two types of identification (as mediating variables), and FIB. We tested our model in a global data set comprising responses of N = 7,225 participants from 23 countries, grouped into nine cultural clusters. Our results indicate that perceived LMX quality was the strongest relative predictor of FIB. Furthermore, the relationships between both perceived LMX quality and identity leadership with FIB were mediated by social identification. The indirect effect of LMX on FIB via social identification was stable across clusters, whereas the indirect effects of the other forms of leadership on FIB via social identification were stronger in countries high versus low on collectivism. Power distance did not influence the relations.