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Folic acid (FA) can reduce the risk for selected birth defects other than neural tube defects. We examined whether FA has preventive effects against fetal abdominal wall defects (AWD) in a unique intervention cohort in China. Birth outcomes of 247 831 singleton births from a population-based cohort study with detailed pre-conceptional FA intake information were collected in China in 1993–1996. Information on births at 20 complete gestational weeks, including live births, stillbirths and pregnancy terminations, and all structural birth defects regardless of gestational week were recorded. The birth prevalence of omphalocele, gastroschisis and total fetal AWD was classified by maternal FA supplementation. The prevalence of total AWD was 4·30 per 10 000 births among women who took FA compared with 13·46 per 10 000 births among those who did not take FA in northern China and 6·28 and 5·18 per 10 000 births, respectively, in southern China. The prevalence of omphalocele was 0·54 per 10 000 births among women who took FA compared with 3·74 per 10 000 births among those who did not take FA in northern China and 1·79 and 1·44 per 10 000 births, respectively, in southern China. FA supplementation significantly prevented total AWD in multivariate analysis (relative risk 0·26, 95 % CI 0·11, 0·61) in northern China, although no preventive effect of FA on AWD was observed in southern China. FA supplementation successfully reduced the prevalence of AWD in northern China. [ABSTRACT FROM AUTHOR]

We present an algorithm from spectral measurements of upwelling water light to estimate the concentration of optically active material (OAM) such as chlorophyll-a (chl-a). The problem of chla concentration retrieval is modelled using a simulated hyperspectral sensor based on spectral measurements. Sensor noise is taken into account during the algorithm development for the best linear estimation of concentration mean and residual variance. In addition, it requires the joint distribution of radiance spectra and chl-a concentration in the algorithm development. This distribution can be obtained by simulation using water-leaving radiance models. The result shows that sensor noise greatly decreases the accuracy of chla concentration retrieval. But the accuracy can also be improved if a priori information concerning observation conditions is known and included in the algorithm. The effects of sensor noise in spectral measurements on retrieval of chl-a concentration are analysed and assessed in the study. This method is applied to the optical properties of the eutrophic water in Nanhu Lake of Changchun, China. The eutrophic water of Nanhu Lake is mainly impacted by the input from rivers and drainage systems from the area of Changchun, which discharge a high concentration of nutrients, mineral suspended solids, and dissolved organic matter (DOM or referred to yellow substance). We measured reflectance spectra (400–900 nm) of Nanhu Lake using the ASD-field spectroradiometer from April to October in 2004. The application of this algorithm shows that neglecting the sensor noise greatly underestimates the accuracy of chl-a retrieval in the study. [ABSTRACT FROM AUTHOR]