An alternative approach to determining average distance in a class of scale-free modular networks

Various real-life networks of current interest are simultaneously scale-free and modular. Here we study analytically the average distance in a class of deterministically growing scale-free modular networks. By virtue of the recursive relations derived from the self-similar structure of the networks, we compute rigorously this important quantity, obtaining an explicit closed-form solution, which recovers the previous result and is corroborated by extensive numerical calculations. The obtained exact expression shows that the average distance scales logarithmically with the number of nodes in the networks, indicating an existence of small-world behavior. We present that this small-world phenomenon comes from the peculiar architecture of the network family.Comment: Submitted for publicactio

Graph Regularized Nonnegative Latent Factor Analysis Model for Temporal Link Prediction in Cryptocurrency Transaction Networks

With the development of blockchain technology, the cryptocurrency based on blockchain technology is becoming more and more popular. This gave birth to a huge cryptocurrency transaction network has received widespread attention. Link prediction learning structure of network is helpful to understand the mechanism of network, so it is also widely studied in cryptocurrency network. However, the dynamics of cryptocurrency transaction networks have been neglected in the past researches. We use graph regularized method to link past transaction records with future transactions. Based on this, we propose a single latent factor-dependent, non-negative, multiplicative and graph regularized-incorporated update (SLF-NMGRU) algorithm and further propose graph regularized nonnegative latent factor analysis (GrNLFA) model. Finally, experiments on a real cryptocurrency transaction network show that the proposed method improves both the accuracy and the computational efficienc

Stochastic bifurcations and tipping phenomena of insect outbreak systems driven by α-stable Lévy processes

In this work, we mainly characterize stochastic bifurcations and tipping phenomena of insect outbreak dynamical systems driven by α-stable Lévy processes. In one-dimensional insect outbreak model, we find the fixed points representing refuge and outbreak from the bifurcation curves, and carry out a sensitivity analysis with respect to small changes in the model parameters, the stability index and the noise intensity. We perform the numerical simulations of dynamical trajectories using Monte Carlo methods, which contribute to looking at stochastic hysteresis phenomenon. As for two-dimensional insect outbreak system, we identify the global stability properties of fixed points and express the probability density function by the stationary solution of the nonlocal Fokker-Planck equation. Through numerical modelling, the phase portrait makes it possible to detect critical transitions among the stable states. It is then worth describing stochastic bifurcation associated with tipping points induced by noise through a careful examination of the dynamical paths of the insect outbreak system with external forcing. The results give new insight into the sensitivity of ecosystems to realistic environmental changes represented by stochastic perturbations

Heterologous expression of a rice \u3ci\u3emiR395\u3c/i\u3e gene in \u3ci\u3eNicotiana tabacum\u3c/i\u3e impairs sulfate homeostasis

Sulfur participates in many important mechanisms and pathways of plant development. The most common source of sulfur in soil –SO42−– is absorbed into root tissue and distributed into aerial part through vasculature system, where it is reduced into sulfite and finally sulfide within the subcellular organs such as chloroplasts and mitochondria and used for cysteine and methionine biosynthesis. MicroRNAs are involved in many regulation pathways by repressing the expression of their target genes. MiR395 family in Arabidopsis thaliana has been reported to be an important regulator involved in sulfate transport and assimilation, and a high-affinity sulphate transporter and three ATP sulfurylases (ATPS) were the target genes of AthmiR395 (Arabidopsis thaliana miR395). We have cloned a miR395 gene from rice (Oryza sativa) and studied its function in plant nutritional response. Our results indicated that in rice, transcript level of OsamiR395 (Oryza sativa miR395) increased under sulfate deficiency conditions, and the two predicted target genes of miR395 were down-regulated under the same conditions. Overexpression of OsamiR395h in tobacco impaired its sulfate homeostasis, and sulfate distribution was also slightly impacted among leaves of different ages. One sulfate transporter (SULTR) gene NtaSULTR2 was identified to be the target of miR395 in Nicotiana tobacum, which belongs to low affinity sulfate transporter group. Both miR395 and NtaSULTR2 respond to sulfate starvation in tobacco

Numerical investigation on rules of fracture propagation during hydraulic fracturing in heterogeneous coal-rock mass

To investigate rules of fracture propagation during hydraulic fracturing in heterogeneous coal-rock mass, a new mathematical model for hydraulic fracturing with seepage-damage coupling and its numerical algorithm are proposed. The rules of coal-rock mass heterogeneity, confining pressure, beforehand hydraulic slotting, and non-symmetric pressure gradient on fracture propagation are investigated. Numerical results show the following: (1) Compared to homogeneous coal-rock mass, the fracture propagation pattern exhibits a more zig-zag characteristic and the fracture initiation pressure is reduced in heterogeneous coal-rock mass. (2) Fracture propagation during borehole fracturing is mainly controlled by confining pressure ratio, and the fracture would propagate along the path with least resistance in coal-rock mass. (3) During hydraulic fracturing with beforehand hydraulic slotting, fracture propagation pattern would become more complex with slotting length increasing; the propagation direction of fracture is primarily controlled by principal stress difference, the larger of principal stress difference, the more difficult of oriented fracturing. (4) Non-symmetric pressure gradient can reduce breakdown pressure and influence fracture propagation pattern, which provides a beneficial guide for oriented fracturing. The simulation results are consistent with the theoretical solutions and experimental observations, which is promising to guide field operation of hydraulic fracturing to improve coalbed methane extraction

Methods and compositions for transgenic plants with enhanced cold tolerance, ability to flower without vernalization requirement and impacted fertility

The present invention provides transgenic plants having increased tolerance to cold and altered flowering characteristics. Also provided are methods and compositions for producing said transgenic plants

Synthesis and kinetic analysis of hydromagnesite with different morphologies by nesquehonite method

514-521Hydromagnesite with different morphologies has been synthesized using self-made nesquehonite whiskers as raw materials. The synthesized samples have been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that porous rod-like hydromagnesite are generated at 328~353K and in the pH value of 9.30+0.2, while irregular flower-like and flat layered ones are synthesized in the pH values of 10.0+0.05 and 11.0+0.05, respectively. The yield of hydromagnesite improved linearly with the increase of the temperatures and solution pH values. Porous rod-like hydromagneiste crystals with good crystalline and uniform morphology are obtained when the pyrolysis time is over 60 min. Furthermore, the apparent activation energy of phase transformation is calculated to be 3.4080 kJ/mol. According to the results, the experimental data can be well described by the kinetic model, suggesting that the phase transfer rate is dependent on the temperature