Decision making during the prenatal diagnostic procedure. A questionnaire and interview study of 211 women participating in prenatal diagnosis

Counselling in connection with prenatal diagnosis (PND) is a common task for the obstetrician and the midwife. However, the decision making processes of pregnant women are not completely known, for instance, the questions of women's autonomy, the decision on how to act in the case of an abnormal test, and the partner's participation in the decision. A questionnaire and interview study was carried out among 211 women undergoing PND by amniocentesis or chorionic villus biopsy. Most women in the sample indicated that PND was completely voluntary. However, at the same time almost every woman reported that it was difficult to decline from PND when offered. Even before the visit to register at the antenatal clinic, most of the women (83 per cent) had made up their minds to have PND. At the time of the test, many of the participants (62 per cent) had decided in favour of a legal abortion if the test indicated an abnormality in the fetus. At the same time, however, the data indicate a need for reflection and ambivalence, which the medical staff have to accept. In the questionnaire most of the women stated that they and their partners had similar attitudes towards PND, but when interviewed 38 per cent of the women admitted some differences between their own attitudes and their partners'. Although some women reported considerable deliberation and ambivalence, most of them said that they would undergo PND in another pregnancy.     

Leaf arrangement

The striking universality of the occurrence of Fibonacci numbers in phyllotaxis is analyzed. Geometric investigation shows that Fibonacci patterns are intimately related to the golden divergence angle along the genetic spiral. A simple argument is presented to make this angle plausible by considering inhibitory action in primary pattern formation. The various types of leaf arrangement are related to the spatial and temporal range of the inhibitory influences.     

Relationship between abundance of rodents and damage to agricultural crops

Developing a relationship between pest abundance and damage to crops is essential for the calculation of economic injury levels (EIL) leading to informed management decisions. The crop modelling framework, APSIM, was used to simulate the impact of mouse damage on yield loss on wheat where a long-term dataset on the density of mice was available (1983–2003). The model was calibrated using results from field trials where wheat plants were hand clipped to imitate mouse damage. The grazing effect of mice was estimated using the population density, daily intake per mouse and the proportion of wheat grain and plant tissue in the diet to determine yield loss. The mean yield loss caused by mice was 12.4% (±5.4S.E.; range −0.5 to 96%). There were 7/21 years when yield loss was >5%. A damage/abundance relationship was constructed and a sigmoidal curve explained 97% of variation when accounting for different trajectories of mouse densities from sowing to harvest. The majority of damage occurred around emergence of the crop when mouse densities were >100 mice ha⁻¹. This is the first time that field data on mouse density and a crop simulation model have been combined to estimate yield loss. The model examines the efficacy of baiting and how to estimate EILs. Because the broadscale application of zinc phosphide is cheap and effective, the EIL is very low (<1% yield loss). The APSIM model is highly flexible and could be used for other vertebrate pests in a range of crops or pastures to develop density/damage relationships and to assist with management.