Microbial community pattern detection in human body habitats via ensemble clustering framework

The human habitat is a host where microbial species evolve, function, and continue to evolve. Elucidating how microbial communities respond to human habitats is a fundamental and critical task, as establishing baselines of human microbiome is essential in understanding its role in human disease and health. However, current studies usually overlook a complex and interconnected landscape of human microbiome and limit the ability in particular body habitats with learning models of specific criterion. Therefore, these methods could not capture the real-world underlying microbial patterns effectively. To obtain a comprehensive view, we propose a novel ensemble clustering framework to mine the structure of microbial community pattern on large-scale metagenomic data. Particularly, we first build a microbial similarity network via integrating 1920 metagenomic samples from three body habitats of healthy adults. Then a novel symmetric Nonnegative Matrix Factorization (NMF) based ensemble model is proposed and applied onto the network to detect clustering pattern. Extensive experiments are conducted to evaluate the effectiveness of our model on deriving microbial community with respect to body habitat and host gender. From clustering results, we observed that body habitat exhibits a strong bound but non-unique microbial structural patterns. Meanwhile, human microbiome reveals different degree of structural variations over body habitat and host gender. In summary, our ensemble clustering framework could efficiently explore integrated clustering results to accurately identify microbial communities, and provide a comprehensive view for a set of microbial communities. Such trends depict an integrated biography of microbial communities, which offer a new insight towards uncovering pathogenic model of human microbiome.Comment: BMC Systems Biology 201

On Homology Roses and the D(2)-problem

For a commutative ring $R$ with a unit, an $R$-homology rose is a topological space whose homology groups with $R$-coefficients agree with those of a bouquet of cirlces. In this paper, we study some special properties of covering spaces and fundamental groups of $R$-homology roses, from which we obtain some result supporting the Carlsson conjecture on free $(Z_p)^r$ actions. In addition, for a group $G$ and a field $F$, we define an integer called the $F$-gap of $G$, which is an obstruction for $G$ to be realized as the fundamental group of a 2-dimensional $F$-homology rose. Furthermore, we discuss how to search candidates of the counterexamples of Wall's D(2)-problem among $F$-homology roses and $F$-acyclic spaces.Comment: 26 pages, no figure; some new results are added to the previous versio

Magnetism and thermodynamics of spin-(1/2,1) decorated Heisenberg chain with spin-1 pendants

The magnetic and thermodynamic properties of a new ferrimagnetic decorated spin-(1/2,1) Heisenberg chain with spin-1 pendant spins are investigated for three cases: (A) J1,J2>0; (B) J1>0, J20, where J1 and J2 are the exchange couplings between spins in the chain and along the rung, respectively. The low-lying and magnetic properties are explored jointly by the real-space renormalization group, spin wave, and density-matrix renormalization group methods, while the transfer-matrix renormalization group method is invoked to study the thermodynamics. It is found that the magnon spectra consist of a gapless and two gapped branches. Two branches in case (C) have intersections. The coupling dependence of low-energy gaps are analyzed. In a magnetic field, an m=3/2 (m is the magnetization per unit cell) plateau is observed for case (A), while two plateaux at m=1/2 and 3/2 are observed for cases (B) and (C). Between the two plateaux in cases (B) and (C), the sublattice magnetizations for the spins coupled by ferromagnetic interactions have novel decreasing regions with increasing the magnetic field. At finite temperature, the zero-field susceptibility temperature product chi*T and specific heat exhibit distinct exotic features with varying the couplings and temperature for different cases. chi*T is found to converge as T approaches zero, which is different from the divergent behavior in the spin-(1/2,1) mixed-spin chain without pendants. The observed thermodynamic behaviors are also discussed with the help of their low-lying excitations.Comment: 10 pages, 8 figures, accepted by Phys. Rev.

Utility greedy discrete bit loading for interference limited multi-cell OFDM system

In this contribution we present the solution of the utility greedy discrete bit loading for interference limited multicell OFDM networks. Setting the utility as the sum of consumed power proportions, the algorithm follows greedy way to achieve the maximum throughput of the system. Simulation has shown that the proposed algorithm has better performance and lower complexity than the traditional optimal algorithm. The discussion of the results is provided