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The calculated backbone torsion angles phi, psi and chi for the 12 alanine and 8 valine residues in the nuclease from Staphylococcus aureus using radioactive carbon chemical shifts, are identical to that of the X-ray determined values when nuclear Overhauser effect distance restraints and J-coupling torsion angle restraints are combined with chemical shift restraints. The fully-restrained set of structures analyzed with and without chemical shift constraints have some nuclear Overhauser effect violations.

Photo cross-linking was used as an active-site structural probe to study the metal ion dependence of the tertiary folding around the internal guide sequence of the Tetrahymena ribozyme. Base pairing enabled this ribozyme to recognize its RNA substrate which formed the P1 duplex that was cleaved in a Mg(2+)-dependent transesterification reaction.

Abstract Background The Hand-Foot-Mouth Disease (HFMD) is the most common infectious disease in China, its total incidence being around 500,000 ~1,000,000 cases per year. The composite space-time disease variation is the result of underlining attribute mechanisms that could provide clues about the physiologic and demographic determinants of disease transmission and also guide the appropriate allocation of medical resources to control the disease. Methods and Findings HFMD cases were aggregated into 1456 counties and during a period of 11 months. Suspected climate attributes to HFMD were recorded monthly at 674 stations throughout the country and subsequently interpolated within 1456 × 11 cells across space-time (same as the number of HFMD cases) using the Bayesian Maximum Entropy (BME) method while taking into consideration the relevant uncertainty sources. The dimensionalities of the two datasets together with the integrated dataset combining the two previous ones are very high when the topologies of the space-time relationships between cells are taken into account. Using a self-organizing map (SOM) algorithm the dataset dimensionality was effectively reduced into 2 dimensions, while the spatiotemporal attribute structure was maintained. 16 types of spatiotemporal HFMD transmission were identified, and 3-4 high spatial incidence clusters of the HFMD types were found throughout China, which are basically within the scope of the monthly climate (precipitation) types. Conclusions HFMD propagates in a composite space-time domain rather than showing a purely spatial and purely temporal variation. There is a clear relationship between HFMD occurrence and climate. HFMD cases are geographically clustered and closely linked to the monthly precipitation types of the region. The occurrence of the former depends on the later.

Abstract Background Neural tube defect (NTD) prevalence in northern China is among the highest worldwide. Dealing with the NTD situation is ranked as the number one task in China's scientific development plan in population and health field for the next decade. Physical and social environments account for much of the disease's occurrence. The environmental determinants and their effects on NTD vary across geographical regions, whereas factors that play a significant role in NTD occurrence may be buried by global statistics analysis to a pooled dataset over the entire study area. This study aims at identification of the local determinants of NTD across the study area and exploration of the epidemiological implications of the findings. Methods NTD prevalence rate is represented in terms of the random field theory, and Rushton's circle method is used to stabilize NTD rate estimation across the geographical area of interest; NTD determinants are represented by their measurable proxy variables and the geographical weighted regression (GWR) technique is used to represent the spatial heterogeneity of the NTD determinants. Results Informative maps of the NTD rates and the statistically significant proxy variables are generated and rigorously assessed in quantitative terms. Conclusions The NTD determinants in the study area are investigated and interpreted on the basis of the maps of the proxy variables and the relationships between the proxy variables and the NTD determinants. No single determinant was found to dominate the NTD occurrence in the study area. Villages where NTD rates are significantly linked to environmental determinants are identified (some places are more closely linked to certain environmental factors than others). The results improve current understanding of NTD spread in China and provide valuable information for adequate disease intervention planning.

The competitive effects of Fe/Mo anti-site defect (ASD) concentration and grain boundary (GB) property on the magnetoresistance (MR) behavior of Sr2FeMoO6 (SFMO) double perovskite are investigated. Two SFMO samples with different ASD concentrations (31% and 14%) were prepared by controlling the different sintering temperature, and then, they were performed several GB modifying treatments. While the ASD remain unchanged, the MR values of both samples were appreciably enhanced since more than thousand times of resistivity had been increased after GB modifying. When compared samples that under the same soaking treatments, the more disorder sample (ASD = 31%) always showed the lower MR value than the ordered (ASD = 14%), regardless of its stronger GB strength. This suggests that the negative effect of ASD always plays an important role in MR behavior and this adverse effect is hardly offset by the increased positive effects of its GB property. [ABSTRACT FROM AUTHOR]