Prenatal diagnosis of cystic fibrosis: I. Prospective study of 51 pregnancies

A prenatal diagnosis was performed in 51 pregnancies with a 1-in-4 risk of having a child with cystic fibrosis. The criteria for determining an affected fetus were based on the results of alkaline phosphatase (ALP) residual activity after inhibition by phenylalanine and by homoarginine, of total ALP activity, and of gamma-glutamyltranspeptidase (GGTP) activity in the amniotic fluid taken between 16 and 19 weeks of pregnancy. The chromosomal analysis of amniotic fluid cells showed trisomy 13 in one case which was excluded from the analysis of biochemical assays. The biochemical assays were in the normal ranges in the amniotic fluid of 35 pregnancies: 26 have reached term and a normal infant has been born, 9 are still in progress. A deficiency of the ALP phenylalanine-inhibitable form, depressed values of total ALP and GGTP were observed in the amniotic fluid of 15 pregnancies: one pregnancy went to term and the infant had CF, in 14 cases the pregnancy was terminated, and meconium ileus was observed in ten of these cases. It was observed that the changes towards abnormal values became more significant with advancing gestational age and that 18 weeks appeared to be the optimum time for diagnostic amniocentesis.     

Usefulness of linkage disequilibrium of KM-19 and XV-2c DNA probes for genetic counselling in a high-risk cf family

A French couple with an individual risk of carrying the cystic fibrosis (CF) mutation of 1/2 sought genetic counselling. From the DNA haplotypes generated by XV-2c and KM-19 RFLPs, it could be deduced that only one subject was a carrier, lowering the risk of having a CF baby from 1/16 to 1/200. The strong linkage disequilibrium between these RFLPs and the CF allele observed in France reduced the risk to 1/1600.     

Prospective maternal serum human chorionic gonadotropin screening for the risk of fetal chromosome anomalies and of subsequent fetal and neonatal deaths

A prospective study of maternal serum human chorionic gonadotrophin (hCG) measurement for the selection of pregnancies with an increased risk of fetal trisomy 21 was undertaken in 24 000 pregnancies from 1 January 1989 to 31 December 1990. Maternal serum was sampled at 15-18 weeks of gestation. hCG was measured in one laboratory, with one technique. This ‘hCG high level’ technique was developed for this screening. Amniocentesis was offered to each woman with a maternal serum hCG level above the cut-off. The follow-up of the pregnancies is known in 92 per cent of cases. The combination of hCG values and maternal age gave a detection efficiency of 63 per cent for trisomy 21 with rates of amniocentesis of 30 per cent for patients aged 37 years, 20 per cent for patients aged 35 or 36 years, and 5 per cent for patients under 35 years of age. Based on this prospective study, an individual risk was calculated combining the serum hCG value and maternal age. Seventy-four per cent of trisomy 13, trisomy 18, triploidy, and 5p- deletion were detected either in the same selected group of women or in combination with ultrasonography performed when hCG values were very low. The follow-up study showed that women who had high or low hCG values represented a group at high risk for fetal or perinatal death.     

Nitrogen fixation on a coral reef

Acetylene reduction was used to assess nitrogen fixation on all major substrates at all major areas over a period of 1 to 6 yr (1980–1986) at One Tree Reef (southern Great Barrier Reef). Experiments using ¹⁵N₂ gave a ratio of 3.45:1.0 for C₂H₂ reduced:N₂ fixed. Acetylene reduction was largely light-dependent, saturated at 0.15 ml C₂H₂ per ml seawater, and linear over 6 h. High fixation was associated with two emergent cyanophyte associations, Calothrix crustacea and Scytonema hofmannii, of limited distribution. Subtidally, the major contribution to nitrogen fixation came from well-grazed limestone substrates with an epilithic algal community in the reef flat and patch reefs (3 to 15 nmol C₂H₄ cm^-2 h^-1). Similar substrates from the outer reef slope showed lower rates. Nitrogen fixation on beach rock, intertidal coral rubble, reef crest and lagoon sand was relatively small (0.3 to 1.0 nmol C₂H₄ cm^-2 h^-1). Seasonal changes in light-saturated rates were small, with slight reduction only in winter. Rates are also reported for experimental coral blocks (13 to 39 nmol cm^-2 h^-1) and for branching coral inside and outside territories of gardening damselfish (3 to 28 nmol cm^-2 h^-1). This work supports the hypothesis that the high nitrogen fixation on the reef flat and patch reefs of the lagoon (34 to 68 kg N ha^-1 yr^-1) is because these subtidal areas support highly disturbed communities with the greatest abundance of nitrogen-fixing cyanophyte algae. It is calculated from a budget of all areas that One Tree Reef has an annual nitrogen fixation rate of 8 to 16 kg N ha^-1 yr^-1.     

Emissions Trading with Shares and Coupons when Control over Discharges Is Uncertain

Two important decisions in designing markets for tradable emissions permits are whether to allow banking of permits (coupons) and whether to allow trading in entitlements to future permits (shares). Banking is predicted to reduce price instability when firms trade in a reconciliation market after the quantity of emissions has been determined. Tradable shares are a common feature in proposals for emissions trading in Canada. We conduct a laboratory experiment to investigate how bankable coupons and tradable shares affect efficiency and prices under uncertainty. Cognitive demands on the subjects are reduced by computerized advice on the optimal allocation of coupons across periods and the implied marginal values of coupons and shares. Banking, share trading, and uncertainty conditions are introduced in a complete factorial design with three observations per cell. High efficiencies are observed across all treatments. Uncertainty in the control of emissions leads to substantial price instability when banking is not allowed. Banking virtually eliminates the instability, but reduces the efficiency of the market institution. Share trading reduces trading volumes, increases price stability, and improves efficiency.     

The problem with [in] management theory

Theory is essential to everything that we do as people studying and practicing industrial/organizational psychology and organizational behavior. But, I think that our field has lost its way recently and become enamored by shiny objects and interesting puzzles. Advancing management theory seems to have become an end state in and of itself. We seemed to be far more concerned with the entertainment value of theories than we are with their scientific rigor or real‐world value. Top journals in our field are mandating that all articles must make a theoretical contribution, and theoretical contributions are being gauged primarily in terms of how innovative, counter‐intuitive, surprising, and interesting they may be. I advocate for a more balanced approach, and in particular, for greater use of abductive inference. I argue that if you start with a real‐world challenge and draw from existing theory, and then develop new theory to understand and change things, you are also making a theoretical contribution. Whether or not we are guided by theory is not really at issue—at issue is how well developed are our theories, how accurate are they, and do they help us to improve organizational life for everyone involved?     

Mayfly (Insecta: Ephemeroptera) community structure as an indicator of the ecological status of a stream in the Niger Delta area of Nigeria

Ephemeroptera is an important group of insects used in the bioassessment and monitoring of freshwater bodies worldwide because of their relative abundance in a wide variety of substrates and their increasing chances of detecting pollution impacts. In this study, their faunistic composition and spatiotemporal variations in density and diversity in River Orogodo (Southern Nigeria) was investigated at five ecologically distinct stations over a 12-month period. The mayfly nymph community responses to environmental variables were evaluated by means of biological measures and multivariate analysis (redundancy analysis [RDA]). Thirteen morphologically distinct taxa belonging to six families were identified. The dominant taxa were Afrobaetodes pusillus (23.1%), Baetis sp. (13.7%), and Caenis cibaria (11.4%). The density of Ephemeroptera differed significantly (p?<?0.05) both in space and time. Diversity was influenced by substrate heterogeneity which in turn was influenced by catchment processes such as flooding and anthropogenic activities especially abattoir effluent. Based on the RDA ordination and relative abundance data, Baetis sp. dominated at impacted stations while a more equitable distribution of species were observed in less disturbed sites. Water velocity, canopy cover, nature of bottom sediments, and the amount of dissolved oxygen also accounted for the variations in Ephemeroptera densities at the different stations. Shannon diversity, taxa richness, and evenness were lowest in station 3 (the abattoir discharge site).     

Scaling the quality of teammates' mental models: equifinality and normative comparisons

We tested the impact of teammates' team and task mental model sharedness on team processes and performance using 70 undergraduate teams that completed a series of missions on a PC‐based flight simulator. Moreover, we considered how the quality of mental models might moderate such relationships. Team processes were found to partially mediate the relationship between task mental model sharedness and team performance. Although team mental model sharedness failed to exhibit a significant linear relationship with team processes or performance, it did evidence a multiplicative relationship as moderated by the quality of those models. Team processes and performance were better among teams sharing higher‐quality team mental models than among teams evidencing less sharedness or who had lower‐quality models. Again, team processes partially mediated these relationships. Results are discussed in terms of the equifinality of mental model quality and applications to various team environments. Copyright © 2005 John Wiley & Sons, Ltd.