Composition of intestinal microflora associated with Yang-deficiency

Objective:In this study,we investigated the composition of the intestinal microflora associated with Yang-deficiency and the function-specific members of this microflora.Method:Subjects with normal and Yang-deficient constitutions were recruited in Beijing,with 30 subjects in each group.Illumina high-throughput sequencing was used to sequence the DNA of their fecal bacteria in the 16S rRNA V3-V4 region.The species abundance and distribution of the intestinal microflora in each specimen were determined with a statistical analysis of these sequences.We identified an underlying taxonomic trend with nonparametric PCoA and other statistical techniques.Results:(1) Subjects with Yang-deficiency displayed more uneven abundances of the taxa in their intestinal microflora than the subjects with normal Yang;(2) several differences were observed in the proportions of certain bacterial groups between the Yang-deficient and control groups;and (3) the fallowing bacteria differed significantly between the two groups:(i) Brevundimonas,Leuconostoc,Turicibacter,Defluviitaleaceae incertae sedis,Rothia,and Butyricimonas were slightly higher in the Yang-deficient subjects,whereas (ii)Megasphaera,Ruminococcus,and Lachnospira were higher in the normal subjects than in the Yang-deficient subjects.

Nested Group Testing Procedure

We investigated the false-negative,true-negative,false-positive,and true-positive predictive values from a general group testing procedure for a heterogeneous population.We show that its false(true)-negative predictive value of a specimen is larger(smaller),and the false(true)-positive predictive value is smaller(larger)than that from individual testing procedure,where the former is in aversion.Then we propose a nested group testing procedure,and show that it can keep the sterling characteristics and also improve the false-negative predictive values for a specimen,not larger than that from individual testing.These characteristics are studied from both theoretical and numerical points of view.The nested group testing procedure is better than individual testing on both false-positive and false-negative predictive values,while retains the efficiency as a basic characteristic of a group testing procedure.Applications to Dorfman’s,Halving and Sterrett procedures are discussed.Results from extensive simulation studies and an application to malaria infection in microscopy-negative Malawian women exemplify the findings.

A theoretic study of a distance-based regression model

The distance-based regression model has many applications in analysis of multivariate response regression in various ?elds, such as ecology, genomics, genetics, human microbiomics, and neuroimaging. It yields a pseudo F test statistic that assesses the relation between the distance(dissimilarity) of the subjects and the predictors of interest. Despite its popularity in recent decades, the statistical properties of the pseudo F test statistic have not been revealed to our knowledge. This study derives the asymptotic properties of the pseudo F test statistic using spectral decomposition under the matrix normal assumption, when the utilized dissimilarity measure is the Euclidean or Mahalanobis distance. The pseudo F test statistic with the Euclidean distance has the same distribution as the quotient of two Chi-squared-type mixtures. The denominator and numerator of the quotient are approximated using a random variable of the form ξχ_d^2+ η, and the approximate error bound is given. The pseudo F test statistic with the Mahalanobis distance follows an F distribution.In simulation studies, the approximated distribution well matched the "exact" distribution obtained by the permutation procedure. The obtained distribution was further validated on H1N1 in?uenza data, aging human brain data, and embryonic imprint data.