Bayesian Quantile Regression for Longitudinal Studies with Nonignorable Missing Data

Summary .  We study quantile regression (QR) for longitudinal measurements with nonignorable intermittent missing data and dropout. Compared to conventional mean regression, quantile regression can characterize the entire conditional distribution of the outcome variable, and is more robust to outliers and misspecification of the error distribution. We account for the within-subject correlation by introducing a   ℓ₂   penalty in the usual QR check function to shrink the subject-specific intercepts and slopes toward the common population values. The informative missing data are assumed to be related to the longitudinal outcome process through the shared latent random effects. We assess the performance of the proposed method using simulation studies, and illustrate it with data from a pediatric AIDS clinical trial.     

The Insufficiency Intake of Dietary Micronutrients Associated with Malnutrition-Inflammation Score in Hemodialysis Population

The relations between dietary micronutrient, nutritional status and inflammation in hemodialysis patients are still unclear. A cross-sectional study was performed in hemodialysis population. 75 hemodialysis patients from South China participated in the dietary and nutritional assessment. Clinical and dietary data were collected. Nutritional status was assessed by Malnutrition-Inflammation Score (MIS) in addition to related anthropometric measurements. And according to the MIS score, the whole hemodialysis patients were divided into normal nutrition group and malnutrition group. The results showed that mid arm circumference (MAC) negatively correlated with MIS (r = −0.425; P = 0.002). The area under the ROC curve (AUC) for MAC was 0.737 (0.614–0.859). Comparing with the normal nutritional group, lower dietary selenium (Se), copper (Cu), iodine (I) and manganese (Mn) intake were observed among patients with malnutrition (P<0.05). While no significant differences of diverse vitamins were found. In conclusion, MAC was effective indicator for assessing nutritional and inflammatory status (P<0.05). The reduction of dietary Se, Cu, I and Mn intake level may be alarming markers for malnutrition and inflammatory status in hemodialysis patients.     

The Influence of Age and Gender on Skin-Associated Microbial Communities in Urban and Rural Human Populations

Differences in the bacterial community structure associated with 7 skin sites in 71 healthy people over five days showed significant correlations with age, gender, physical skin parameters, and whether participants lived in urban or rural locations in the same city. While body site explained the majority of the variance in bacterial community structure, the composition of the skin-associated bacterial communities were predominantly influenced by whether the participants were living in an urban or rural environment, with a significantly greater relative abundance of Trabulsiella in urban populations. Adults maintained greater overall microbial diversity than adolescents or the elderly, while the intragroup variation among the elderly and rural populations was significantly greater. Skin-associated bacterial community structure and composition could predict whether a sample came from an urban or a rural resident ~5x greater than random.     

Kinetics of nitrate and sulfate removal using a mixed microbial culture with or without limited-oxygen fed

The biological degradation of nitrate and sulfate was investigated using a mixed microbial culture and lactate as the carbon source, with or without limited-oxygen fed. It was found that sulfate reduction was slightly inhibited by nitrate, since after nitrate depletion the sulfate reduction rate increased from 0.37 mg SO₄ ^2?/mg VSS d to 0.71 mg SO₄ ^2?/mg VSS d, and the maximum rate of sulfate reduction in the presence of nitrate corresponded to 56 % of the non-inhibited sulfate reduction rate determined after nitrate depleted. However, simultaneous but not sequential reduction of both oxy-anions was observed in this study, unlike some literature reports in which sulfate reduction starts only after depletion of nitrate, and this case might be due to the fact that lactate was always kept above the limiting conditions. At limited oxygen, the inhibited effect on sulfate reduction by nitrate was relieved, and the sulfate reduction rate seemed relatively higher than that obtained without limited-oxygen fed, whereas kept almost constant (0.86–0.89 mg SO₄ ^2?/mg VSS d) cross the six R_OS states. In contrast, nitrate reduction rates decreased substantially with the increase in the initial limited-oxygen fed, showing an inhibited effect on nitrate reduction by oxygen. Kinetic parameters determined for the mixed microbial culture showed that the maximum specific sulfate utilization rate obtained (0.098?±?0.022 mg SO₄ ^2?/(mg VSS h)) was similar to the reported typical value (0.1 mg SO₄ ^2?/(mg VSS h)), also indicating a moderate inhibited effect by nitrate.     

Patent Deployment Strategies and Patent Value in LED Industry

This study applies two variables in the measurement of company patent deployment strategies: patent family depth and earn plan ratio. Patent family depth represents the degree to which certain fields and markets are valued by the patent owner. Earn plan ratio defined as the ratio of the number of patent forward citations to patent family size. Earn plan ratio indicates the degree to which a patent family could be cited by later innovators and competitors. This study applies a logistic regression model in the analysis LED industry data. The results demonstrate that patent value has a positive relationship with the patent family depth, and earn plan ratio.     

Identification of Key Factors Involved in the Biosorption of Patulin by Inactivated Lactic Acid Bacteria (LAB) Cells

The purpose of this study was to identify the key factors involved in patulin adsorption by heat-inactivated lactic acid bacteria (LAB) cells. For preventing bacterial contamination, a sterilization process was involved in the adsorption process. The effects of various physical, chemical, and enzymatic pre-treatments, simultaneous treatments, and post-treatments on the patulin adsorption performances of six LAB strains were evaluated. The pre-treated cells were characterized by scanning electron microscopy (SEM). Results showed that the removal of patulin by viable cells was mainly based on adsorption or degradation, depending on the specific strain. The adsorption abilities were widely increased by NaOH and esterification pre-treatments, and reduced by trypsin, lipase, iodate, and periodate pre-treatments. Additionally, the adsorption abilities were almost maintained at pH 2.2–4.0, and enhanced significantly at pH 4.0–6.0. The effects of sodium and magnesium ions on the adsorption abilities at pH 4 were slight and strain-specific. A lower proportion of patulin was released from the strain with higher adsorption ability. Analyses revealed that the physical structure of peptidoglycan was not a principal factor. Vicinal OH and carboxyl groups were not involved in patulin adsorption, while alkaline amino acids, thiol and ester compounds were important for patulin adsorption. Additionally, besides hydrophobic interaction, electrostatic interaction also participated in patulin adsorption, which was enhanced with the increase in pH (4.0–6.0).