The Limit Behavior Of The Trajectories of Dissipative Quadratic Stochastic Operators on Finite Dimensional Simplex

The limit behavior of trajectories of dissipative quadratic stochastic operators on a finite-dimensional simplex is fully studied. It is shown that any dissipative quadratic stochastic operator has either unique or infinitely many fixed points. If dissipative quadratic stochastic operator has a unique point, it is proven that the operator is regular at this fixed point. If it has infinitely many fixed points, then it is shown that $\omega-$ limit set of the trajectory is contained in the set of fixed points.Comment: 14 pages, accepted in Difference Eq. App

High-throughput bioaccumulation, biotransformation, and production of silver and selenium nanoparticles using genetically engineered Pichia pastoris

A genetically modified Pichia pastoris strain overexpressing a metal-resistant variant of cytochrome b5 reductase enzyme was developed for silver and selenium biosorption and for nanoparticle production. The maximum recombinant enzyme expression level was approximately 31 IU/ml in the intercellular fluid after 24 h of incubation, and the capacity of the recombinant biomass for the biosorption of silver and selenium in aqueous batch models were measured as 163.90 and 63.71 mg/g, respectively. The ions were reduced in the presence of enzyme, leading to the formation of stable 70–180 nm metal nanoparticles. Various instrumental analyses confirmed the well-dispersed and crystalline nature of the spherical nanometals. The purified silver and selenium nanoparticles exhibited at least 10-fold less cytotoxicity toward HDF, EPG85–257, and T47D cells than silver nitrate and selenium dioxide. These results revealed that the engineered Pichia strain is an eco-friendly, rapid, high-throughput, and versatile reduction system for nanometal production

Brane f(R)f(\cal R) gravity

We consider a brane world scenario in which the bulk action is assumed to have the form of a generic function of the Ricci scalar $f(\mathcal{R})$ and derive the resulting Einstein field equations on the brane. In a constant curvature bulk a conserved geometric quantity appears in the field equations which can be associated with matter. We present cosmological and spherically symmetric solutions by assuming specific forms for $f(\mathcal{R})$ and show that the former can explain an accelerated expanding universe while the latter may account for galaxy rotation curves.Comment: 8 pages, 2 figures, to appear in EP

Spatial changes of beach profiles for a small tidal inlet (Currumbin Creek, Australia)

Many tidal inlets are actively monitored to investigate the change in flood or ebb shoals, as these sand deposits can have a major influence on the sediment budget of the adjacent coast. However, here it is hypothesized that the shores of the back barrier area can also act as a source of sediment to be considered in the sediment budget. Therefore, profile changes around Currumbin Creek tidal inlet were considered to identify the extent of such a contribution on the surrounding beach and the overall evolution of the inlet system. The results of 16 weeks survey showed that in general, the shores of the back barrier lagoon had a very marginal effect in the provision of material to the sand budget, although the gorge area is highly vulnerable and dynamic. Even an intense storm event and heavy rainfall during the data collection period, resulting in erosion of the surrounding beaches, showed no significant influence on the shore face of the lagoon

Stemming text-based web page classification using machine learning algorithms: a comparison

The research aim is to determine the effect of word-stemming in web pages classification using different machine learning classifiers, namely Naive Bayes (NB), k-Nearest Neighbour (k-NN), Support Vector Machine (SVM) and Multilayer Perceptron (MP). Each classifiers' performance is evaluated in term of accuracy and processing time. This research uses BBC dataset that has five predefined categories. The result demonstrates that classifiers' performance is better without word stemming, whereby all classifiers show higher classification accuracy, with the highest accuracy produced by NB and SVM at 97% for F1 score, while NB takes shorter training time than SVM. With word stemming, the effect on training and classification time is negligible, except on Multilayer Perceptron in which word stemming has effectively reduced the training time

Virial mass in DGP brane cosmology

We study the virial mass discrepancy in the context of a DPG brane-world scenario and show that such a framework can offer viable explanations to account for the mass discrepancy problem. This is done by defining a geometrical mass $\mathcal{N}$ that we prove to be proportional to the virial mass. Estimating $\mathcal{N}$ using observational data, we show that it behaves linearly with $r$ and has a value of the order of $M_{200}$, pointing to a possible resolution of the virial mass discrepancy. We also obtain the radial velocity dispersion of galaxy clusters and show that it is compatible with the radial velocity dispersion profile of such clusters. This velocity dispersion profile can be used to differentiate various models predicting the virial mass.Comment: 12 pages, 1 figure, to appear in CQ

In vitro and in vivo antifungal properties of silver nanoparticles against Rhizoctonia solani, a common agent of rice sheath blight disease

Sheath blight disease in rice has caused major crop losses worldwide. Managing the causal agent of disease Rhizoctonia solani Kühn is difficult because of its broad host range and formation of sclerotia which can survive in harsh environmental conditions; therefore developing innovative disease management methods without application of hazardous chemicals has been considered as the main concern to maintain sustainable agriculture. This presented research has revealed the negative impact of Silver nanoparticles (SNPs) on R. solani and disease progress both in vitro and in vivo. The adverse effects of the SNPs on R. solani are significantly dependent on the quantity of SNPs, sprayed at different concentrations in vitro. The highest inhibition level against sclerotia formation and mycelia growth are 92 and 85%, respectively, at a SNPs concentration of 50 ppm. In vivo glasshouse experiments also showed that SNPs at the same concentration favorably affects both the fresh and dry weight of rice plants with a remarkable suppressive effect on the lesion development in leaves