Four nucleon pickup studies on medium-weight and heavy nuclei with the (d, 6Li) reaction

This thsis summarizes several years of experimental work performed at the "Kernfysisch Versneller Instituut" in Groningen. Medium-weight and heavy nuclei were studied with the (d,6Li) reaction at a bombarding energy of MeV. The present study will focus on nuclei with mass A > 70 with an emphasis on nuclei in the A = 100 mass region. ... Zie: Summar

Rolpredisposisies in taakgroepe

D.Litt et Phil.Questions relating to organisational roles in industry are studied in terms of personality factors as well as the associated group behaviours. A two dimensional model is conceptually constructed according to which eight role sets can be placed in relation to Introversion vs Extroversion on one axis and Group vs Self Orientation on the other. The research is aimed at establishing the homogeneity of natural work groups and comparing the preferred team role profiles of different groups with one another. By means of the procedure and methodology used in the study it becomes possible to analyse group compositions, establish role requirements and to compare these role requirements with an individual's role preferences. A questionnaire, that measures a person's predisposition towards these roles, was used for ranking the order of 1415 respondent's role preferences. The statistical significance of the homogeneity of 40 organisational job groups are calculated by means of the Kendall Coefficient of Concordance and reported in the study. The different group profiles are compared using the Chi-square statistic for 2x2 tables. By means of this comparison, the similarities and differences between job groups are indicated in terms of status level, hierarchical relationships, titles and job types. Significant homogeneity, below the 0.05% level, is reported for 90% of the job-related groups selected for the study. Of these homogeneous groups, 75% indicated significance levels below 0.001%. The similarities and differences between groups were identified for each role set and meaningful conclusions could be reached regarding the reasons why these differences were observed. The conclusions drawn from the study are that job-related groups are homogeneous in terms of role composition, that differences between groups are significant, and that the extent of a person's adaptation to meet the requirements of another role can be judged according to his predispositions towards that role

Iron catalyzed oxidation chemistry:from C-H bond activation to DNA cleavag

The synthetic iron complex Fe(N4Py) can be employed as a catalyst in the aerobic oxidation of DNA. The resulting oxidized DNA strand is rather unstable and results in cleavage of the DNA strand into two pieces. As for now, it was only possible with Fe(N4Py) or other synthetic iron complexes as catalyst to cut only one DNA strand at the same time. The covalent linking of two Fe(N4Py) complexes together results in a new dinuclear complex, which is capable of addressing both DNA stands at the same time. This is a very interesting finding, since the mechanism of action of many anticancer drugs (such as the natural compound bleomycin) relies on this property. In another benchmark reaction, namely the oxidation of cyclohexane with peracids as oxidants catalyzed by Fe(N4Py), a high-valent iron(IV) oxo intermediate was found to be responsible for the oxidation activity. The presence of this species has been established with various spectroscopic techniques and it is plausible that in many other oxidation processes this intermediates plays an important role

Determinants of Advanced Bone Age in Childhood Obesity

Background: Childhood obesity is associated with advanced bone age (BA). Previous studies suggest that androgens, oestrogens, sex hormone-binding globulin, and insulin are responsible for this phenomenon, but results are contradictory and might be biased by confounders. We aim to elucidate this matter by applying a multivariate approach. Method: We performed a correlation analysis of BA standard deviation score (SDS) with age- and sex-specific SDS for androgens, oestrogens, and with indicators of insulin secretion derived from oral glucose tolerance testing, in a group of obese children. A multivariate analysis was performed to investigate which parameters were independently predictive of BA SDS. Results: In this cohort (n = 101; mean age 10.9 years; mean BA 11.8 years; mean BMI SDS 3.3), BMI SDS was significantly correlated to BA SDS (r = 0.55, p < 0.001). In a regression analysis in the total cohort (B = 0.27, p < 0.001) as well as in females (B = 0.34, p = 0.042), males (B = 0.31, p = 0.006), and pubertal children (B = 0.32, p = 0.046), dehydroepiandrosterone sulphate (DHEAS) showed a positive, independent association with BA SD