Statistical package for windows

All statistical analyses were performed using the Statistical Package for Windows (version 13.00; SPSS, Chicago, IL, USA). The suitable parameters of N efficiency screening can be screened out though the coefficient of variation of each parameter among different cultivars and the correlation between each parameter. The coefficient of variation can reflect the differences between alfalfa cultivars. The correlation between parameters can reflect the importance of parameters. Correlations between the investigated parameters were established by calculating simple pair-wise correlation coefficients. The comprehensive analysis of N efficiency of alfalfa cultivars were obtained by membership function and compounding operation. The membership function method can eliminate the inherent biological and genetic differences between different alfalfa cultivars, as well as the differences between dimensions and orders of different parameters (traits). The weight values of evaluation parameters were obtained by empirical weighting. Twenty-eight alfalfa cultivars were classified by cluster analysis under different N levels. And then, four types of N efficiency were determined though the results of cluster analysis and compounding value of N efficiency. The experimental data were analyzed using ANOVA and Tukey test at a significance level of p < 0.05.

A cross-sectional study was conducted in a university clinic of perinatology affiliated to Tehran University of Medical Sciences in Tehran, where pregnant women attended for screening and routine visits between 2010 and 2012. Pregnant women between 20 and 39 years of age were eligible to enter the study if there was no bilateral blindness, absence of accompanied medical conditions, and no history of medications used during pregnancy but the administered supplements. Those with abortion or who were lost to followup were excluded from the study.
Research ethics committee of TUMS reviewed and then approved the study protocol and informed consent was obtained from each patient before entering the study. Patients were examined for visual acuity in each trimester and 3 months after delivery by an optometrist using the Snellen chart in a 6-meter distance assessing the distance and a 40-centimeter chart for near vision. At each visit, patients' physical and clinical findings were also recorded in a designed questionnaire. Data were then analyzed by Statistical Package for windows (SPSS, 15, Inc., Chicago) using repeated measure ANOVA; the values were considered significant at P < 0.05.