[Spatial Variability and Distribution Pattern of Soil Organic Matter in a Mollisol Watershed of China].

Spatial variability of soil organic matter and its distribution pattern are the hot issues of soil scientific research. Selecting Haigouhe watershed as the study area, this paper mainly focused on the spatial variability, distribution pattern and its impact factors of SOM in the surface soil by classical statistics, Geo-statistics and "3S" technology. The results showed that: compared with the other black soil areas, the SOM content in Haigouhe watershed was a little lower, there was a spatial autocorrelation, and a moderate variability. Random factors, such as human activities, cultivation measures and so on, had little impact on the spatial variation, while the structural factors had a dominant function, and there was a remarkable spatial anisotropy of SOM. The SOM content reduced gradually from east to west with the familiar changes of height, so the co-kriging interpolation, selecting elevation as the co-variate, was employed to improve the accuracy. The spatial variability of SOM and its distribution pattern in Haigouhe watershed were greatly affected by topography and land use but weakly influenced by traffic, villages and other social factors. The surrounding environment of the samples would increase the uncertainty of spatial variability and interpolation of SOM and it cannot be ignored in future studies. In summary, it was a significant scientific research to analyze the spatial variability, distribution pattern of SOM and its main impact factors in a mollisol hilly watershed of China.

Glycated albumin may be a choice, but not an alternative marker of glycated hemoglobin for glycemic control assessment in diabetic patients undergoing maintenance hemodialysis.

BACKGROUND: It has been suggested that glycated hemoglobin (HbA1c) underestimate the actual glycemic control levels in maintenance hemodialysis (MHD) patients, because of anemia and the using of erythropoietin (EPO); it was recommended that glycated albumin (GA) should be an alternative marker. Therefore, the assessment performances of glycemic control were compared between GA and HbA1c in this research by referring to mean plasma glucose (MPG) in diabetes mellitus (DM) patients undergoing MHD or not. METHODS: MPG was calculated according to the data registered at enrollment and follow-up 2 months later and corresponding HbA1c, albumin (ALB), GA, etc. were measured in 280 cases. A case-control study for comparing GA and HbA1c was done among the groups of MHD patients with DM (n=88) and without DM (NDM; n=90), and non-MHD ones with DM (n=102) using MPG for an actual glycemic control standard. RESULTS: In these 3 groups, only for DM patients' (whether undergoing MHD or not), GA and HbA1c correlated with MPG significantly (P < 0.01). Through linear regression analysis, it could be found that the regression curves of GA almost coincided in MHD and non-MHD patients with DM, because the intercepts (2.418 vs. 2.329) and slopes (0.053 vs. 0.057) were very close to each other. On the contrary, regression curves of HbA1c did not coincide in the two groups, because variance of the slopes (0.036 vs. 0.052) were relatively large. Through comparing receiver operating characteristic (ROC) areas under the curve (AUC), it could be understood that the assessment performances of GA and HbA1c in MHD patients were lower than those in non-MHD ones, and assessment performance of HbA1c in MHD patients was better than GA (P < 0.05). In addition, the effects of Hb and EPO dose on HbA1c, or that of ALB on GA were unobvious in our study. CONCLUSIONS: Actual glycemic control level in MHD patients with DM may be underestimated by HbA1c, and it could be avoided by GA; however, glycemic evaluating performance of HbA1c may be still better than that of GA. Therefore, HbA1c should not be replaced completely although GA can be used as a choice to monitor glycemic level.

Multiscale peak alignment for chromatographic datasets.

Chromatography has been extensively applied in many fields, such as metabolomics and quality control of herbal medicines. Preprocessing, especially peak alignment, is a time-consuming task prior to the extraction of useful information from the datasets by chemometrics and statistics. To accurately and rapidly align shift peaks among one-dimensional chromatograms, multiscale peak alignment (MSPA) is presented in this research. Peaks of each chromatogram were detected based on continuous wavelet transform (CWT) and aligned against a reference chromatogram from large to small scale gradually, and the aligning procedure is accelerated by fast Fourier transform cross correlation. The presented method was compared with two widely used alignment methods on chromatographic dataset, which demonstrates that MSPA can preserve the shapes of peaks and has an excellent speed during alignment. Furthermore, MSPA method is robust and not sensitive to noise and baseline. MSPA was implemented and is available at http://code.google.com/p/mspa.