Down syndrome maternal serum marker screening after 18 weeks' gestation

Women having access to prenatal care late in pregnancy may still wish to benefit from maternal serum screening for Down syndrome. Therefore, we established reference values for α-feto protein (AFP) and free β-human chorionic gonadotrophin (β-hCG), and assessed the diagnostic value of maternal serum marker screening at 18–35 weeks' gestation based upon a series of 4072 sera from unaffected pregnancies and 118 sera from pregnant women with fetuses affected by Down syndrome. Using a 1/250 risk cut-off, a detection rate of 72.9% (95% CI = 71.5–74.3%) was achieved with a false-positive rate of 7.51% (95% CI = 6.71–8.3%). This was not significantly different from the percentages observed in our 14–17 weeks routine screening (50 596 patients): 71.9% (95% CI = 71.5–72.3%) and 6.48% (95% CI = 6.28–6.68%), respectively. Detection and screen-positive rates were, respectively, 51.3% (95% CI = 35.6–67.0%) and 5.95% (95% CI = 5.12–6.68%) in women aunder 35 years of age, and 84.8% (95% CI = 76.9–92.7%) and 24% (95% CI = 20.7–27.3%) in women aged 35 years and over. In conclusion, maternal serum marker screening is feasible at 18 weeks' gestation and later, which may be of interest in selected cases. Copyright © 2002 John Wiley & Sons, Ltd.     

Morphology, chemistry and distribution of neoformed spherulites in agricultural land affected by metallurgical point-source pollution

Metal distribution patterns in superficial soil horizons of agricultural land affected by metallurgical point-source pollution were studied using optical and electron microscopy, synchrotron radiation and spectroscopy analyses. The site is located in northern France, at the center of a former entry lane to a bunker of World War II, temporarily paved with coarse industrial waste fragments and removed at the end of the war. Thin sections made from undisturbed soil samples from A and B horizons were studied. Optical microscopy revealed the occurrence of yellow micrometer-sized (Ap horizon) and red decamicrometer-sized spherulites (AB, B(1)g horizons) as well as distinct distribution patterns. The chemical composition of the spherulites was dominated by Fe, Mn, Zn, Pb, Ca, and P. Comparison of calculated Zn stocks, both in the groundmass and in spherulites, showed a quasi-exclusive Zn accumulation in these neoformed features. Their formation was related to several factors: (i) liberation of metal elements due to weathering of waste products, (ii) Ca and P supply from fertilizing practices, (iii) co-precipitation of metal elements and Ca and P in a porous soil environment, after slow exudation of a supersaturated soil solution in more confined mineral media.     

Costs and benefits of preventing workplace accidents: The case of participatory ergonomics

This paper provides a cost-benefit analysis of a participatory ergonomics program conducted at the beginning of the 1990s to reduce back-related disorders among packers at a warehouse of the Société des Alcools du Québec in Quebec City. After evaluating the costs of the program, we present a rigorous econometric analysis to assess how many accidents have been prevented by the program so as to compute the direct and indirect costs avoided as a result of such accident reduction. We show that the program has indeed been profitable for the firm.     

Gaseous nitrogen losses from a forest site in the North Tyrolean Limestone Alps

Microorganisms are responsible for the mineralisation of organic nitrogen in soils. NH ⁺₄ can be further oxidised to NO₃ ⁻ during nitrification and NO₃ ⁻ can be reduced to gaseous nitrogen compounds during denitrification. During both processes, nitrous oxide (N₂O), which is known as greenhouse gas, can be lost from the ecosystem.

The aim of this study was to quantify N₂O emissions and the internal microbial N cycle including net N mineralisation and net nitrification in a montane forest ecosystem in the North Tyrolean Limestone Alps during an 18-month measurement period and to estimate the importance of these fluxes in comparison with other components of the N cycle. Gas samples were taken every 2 weeks using the closed chamber method. Additionally, CO₂ emission rates were measured to estimate soil respiration activity. Net mineralisation and net nitrification rates were determined by the buried bag method every month. Ion exchange resin bags were used to determine the N availability in the root zone.

Mean N₂O emission rate was 0.9 kg N ha⁻a⁻, which corresponds to 5 % of the N deposited in the forest ecosystem. The main influencing factors were air and soil temperature and NO ⁻₃ accumulated on the ion exchange resin bags. In the course of net ammonification, 14 kg NH ⁺₄ −N ha⁻ were produced per year. About the same amount of NO ⁻₃ −N was formed during nitrification, indicating a rather complete nitrification going on at the site. NO ^t-₃ concentrations found on the ion exchange resin bags were about 3 times as high as NO ^t-₃ produced during net nitrification, indicating substantial NO ^t-₃ immobilisation. The results of this study indicate significant nitrification activities taking place at the Mühleggerköpfl.

     

Egg survival,embryonic development,and larval characteristics of northern shrimp (<Emphasis Type="Italic">Pandalus borealis</Emphasis>) females subject to different temperature and feeding conditions

Laboratory experiments on ovigerous females of northern shrimp (Pandalus borealis) were used to assess the effects of temperature and food ration on female condition during incubation and examine how combined effects of temperature and female condition influenced egg survival, embryonic development, and larval characteristics. Ovigerous females were maintained at 2°C, 5°C, and 8°C and fed on a low (three times/week; 2–2.7% W/W) or high ration (five times/week at satiation). The increase in temperature accelerated the developmental time of the eggs but their survival at 8°C was reduced. Conversion efficiency of yolk reserves in developing embryos was significantly reduced at elevated temperatures and larvae hatching at 2°C and 5°C were significantly larger and heavier than those hatching at 8°C. The experimental design did not result in any effect of food ration on the energetic condition of females or on egg characteristics and their biochemical composition. However, lower energy reserves were observed for females held at 8°C.