Efficient clustering in collaborative filtering recommender system: Hybrid method based on genetic algorithm and gravitational emulation local search algorithm

The ultimate goal of the Recommender System (RS) is to offer a proposal that is very close to the user's real opinion. Data clustering can be effective in increasing the accuracy of production proposals by the RS. In this paper, single-objective hybrid evolutionary approach is proposed for clustering items in the offline collaborative filtering RS. This method, after generating a population of randomized solutions, at each iteration, improves the population of solutions first by Genetic Algorithm (GA) and then by using the Gravitational Emulation Local Search (GELS) algorithm. Simulation results on standard datasets indicate that although the proposed hybrid meta-heuristic algorithm requires a relatively high run time, it can lead to more appropriate clustering of existing data and thus improvement of the Mean Absolute Error (MAE), Root Mean Square Error (RMSE) and Coverage criteria.     

Promoter methylation analysis of WNT/β-catenin pathway regulators and its association with expression of DNMT1 enzyme in colorectal cancer

Background

Aberrant DNA methylation as the most important reason making epigenetic silencing of genes is a main mechanism of gene inactivation in patients with colorectal cancer. In this study, we decided to identify promoter methylation status of ten genes encoding WNT negative regulators, and measure the expression of DNMT1 enzyme in colorectal cancer samples.

Results

Aberrant methylation of APC gene was statistically significant associated with age over 50 (p = 0.017), DDK3 with male (p < 0.0001), SFRP4, WIF1, and WNT5a with increasing tumor stage (p = 0.004, p = 0.029, and p = 0.004), SFRP4 and WIF1 with tumor differentiation (p = 0.009 and p = 0.031) and SFRP2 and SFRP5 with histological type (p = 0.001 and p = 0.025). The increasing number of methylated genes correlated with the expression levels of the DNMT1 mRNA.

Conclusions

The rate of gene promoter methylation of WNT pathway regulators is high in colorectal cancer cells. Hyper-methylation is associated with increased expression of the DNMT1 enzyme.     

Association Between Hypertension in Healthy Participants and Zinc and Copper Status: a Population-Based Study

Biological Trace Element Research - The prevalence of hypertension (HTN) is increasing globally. It has been shown that there is an association between micronutrient deficiency and HTN. In the...     

Flow cytometric method for quantifying viable Mycoplasma agassizii,an agent of upper respiratory tract disease in the desert tortoise (Gopherus agassizii)

Aims: Mycoplasma agassizii can cause upper respiratory tract disease in the threatened desert tortoise of the Southwestern United States. Two technical challenges have impeded critical microbiological studies of this microorganism: (i) its small size limits the use of light microscopy for cell counting and (ii) its extremely slow growth in broth and agar cultures impedes colony counting. Our aim was to develop a rapid and sensitive flow cytometric method using a vital fluorescent dye to enumerate viable M. agassizii cells. Methods and Results: Here, we demonstrate that the nonfluorescent molecule 5‐carboxyfluorescein (5‐CF) diacetate acetoxymethyl ester penetrates M. agassizii cell membranes and it is converted in the cytoplasm to the fluorescent molecule 5‐CF by the action of intracellular esterases. Labelled mycoplasma cells can be easily detected by flow cytometry, and cultures with as few as 100 viable mycoplasma cells ml^?1 can be labelled and counted in less than 1 h. Experiments using temperature‐induced cell death demonstrated that only viable M. agassizii cells are labelled with this procedure. Conclusions: A rapid and sensitive flow cytometric technique has been developed for enumerating viable M. agassizii cells. Significance and Impact of the Study: This technique should facilitate basic immunological, biochemical and pharmacological studies of this important pathogen which may lead to new diagnostic and therapeutic methods.     

Multiparasitism of stink bug eggs: competitive interactions between Ooencyrtus pityocampae and Trissolcus agriope

Females of Trissolcus agriope (Platygastridae) avoid host (Brachynema signatum) eggs parasitized by conspecifics or Ooencyrtus pityocampae (Encyrtidae), but females of the latter species will superparasitize and multiparasitize, although they mostly attack unparasitized eggs. Females of T. agriope were more efficient in the laboratory and parasitized more hosts in 24 and 48 h. In multiparasitized hosts, O. pityocampae was a superior larval competitor and could complete also development as a facultative hyperparasitoid. When females of both species foraged together, T. agriope parasitized significantly more than O. pityocampae, about 50 % in both cases, although O. pityocampae almost doubled its parasitism rate as the exposure period was lengthened from 24 to 48 h. When O. pityocampae followed T. agriope in sequential foraging bouts, the former species successfully parasitized more hosts than the latter. The advisability of co-releases of both species to improve biological control of first generation B. signatum in Iranian pistachio orchards is discussed.     

Electronic properties and stability phase diagrams for cubic BN surfaces

This contribution investigates structural and electronic properties as well as stability phase diagrams of surfaces of the cubic boron nitride (c-BN). Our calculated parameters for bulk c-BN agree reasonably well with both experimental and computed values available in the literature. Based on the energies of the three experimentally recognised phases of bulk boron, i.e. α-B₃₆, β-B₁₀₅ and γ-B₂₈, we estimate enthalpy of formation of c-BN to be ?2.8 eV. The c-BN(1?0?0) surface offers separate B and N terminations (denoted as c-BN(1?0?0)_B and c-BN(1?0?0)_N), whereas c-BN(1?1?1) and c-BN(1?1?0) are truncated with combinations of boron and nitrogen atoms (denoted as c-BN(1?1?1)_BN and c-BN(1?1?0)_BN). Optimised geometries of surfaces display interlayer displacements up to the three topmost layers. Downward displacement of surface boron atoms signifies a common geometric feature of all surfaces. Bulk c-BN and its most stable surface c-BN(1?0?0)_N possess no metallic character, with band gaps of 5.46 and 2.7 eV, respectively. We find that, only c-BN(1?0?0)_B configuration exhibits a metallic character. c-BN(1?1?0)_BN and c-BN(1?1?1)_BN surfaces display corresponding band gaps of 2.5 and 3.9 eV and, hence, afford no metallic property.     

Comparative modeling of CCRL1, a key protein in masked immune diseases and virtual screening for finding inhibitor of this protein

Human CCRL1 belongs to the family of silent chemokine receptors. This transmembrane protein plays a role in blunting function of chemokines through binding to them. This will attenuate immune responses. Interaction between CCRL1 and CCL21 determines this immune extinction. Thus inhibiting the action of this atypical chemokine seems to stimulate immune responses especially in the case of suppressed and immune deficient conditions. In this study we predicted 3D structure of CCRL1 using comparative modeling and Hiddebn Markov Model algorithm. Final predicted model optimized by Modeller v9.8 and minimized regarding energy level using UCSF chimera candidate version1.5.3. ClasPro webserver was used to find interacting residues between CCRL1 and CCL21. Interacting residues were used as target for chemical inhibitors by simulated docking study. For finding potential inhibitors, library of KEGG compounds screened and 97 obtained chemicals docked against interacting residues between CCRL1- CCL21 and MolDock was used as docking scoring function. Results indicated that Hexadecanal is a potential inhibitor of CCRL1- CCL21 interaction. Inhibition of this interaction will increase intercellular level of CCl21 and interaction between CCL21 and CCR7 causes immune potentiaiton.