Graph Community Infomax

Graph representation learning aims at learning low-dimension representations for nodes in graphs, and has been proven very useful in several downstream tasks. In this article, we propose a new model, Graph Community Infomax (GCI), that can adversarial learn representations for nodes in attributed networks. Different from other adversarial network embedding models, which would assume that the data follow some prior distributions and generate fake examples, GCI utilizes the community information of networks, using nodes as positive(or real) examples and negative(or fake) examples at the same time. An autoencoder is applied to learn the embedding vectors for nodes and reconstruct the adjacency matrix, and a discriminator is used to maximize the mutual information between nodes and communities. Experiments on several real-world and synthetic networks have shown that GCI outperforms various network embedding methods on community detection tasks.

Two-dimensional N-doped Pd/carbon for highly efficient heterogeneous catalysis

A novel two-dimensional ZIF-derived Pd@CN prepared via one-step calcination exhibits outstanding catalytic activity in heterogeneous catalysis. The well-developed porous structure, low dimension and low density make active sites more accessible....

Strange attractor in earthquake swarms near Valsad (Gujarat), India

Valsad district in south Gujarat near the western coast of the peninsular India experienced earthquake swarms since early February 1986. Seismic monitoring through a network of micro earthquake seismographs showed a well concentrated seismic activity over an area of 7 × 10 km2 with the depth of foci extending from 1 to 15 km. A total number of 21,830 earthquakes were recorded during March 1986 to June 1988. The daily frequency of earthquakes for this period was utilized to examine deterministic chaos through evaluation of dimension of strange attractor and Lyapunov exponent. The low dimension of 2.1 for the strange attractor and positive value of the largest Lyapunov exponent suggest chaotic dynamics in Valsad earthquake swarms with at least 3 parameters for earthquake predictability. The results indicate differences in the characteristics of deterministic chaos in intraplate and interplate regions of India.

A Simple and Low-Cost Method for Fabrication of Polydimethylsiloxane Microfludic Chips

The conventional fabrication methods for enrichment microfluidic devices require cleanroom, which are costly and time-consuming. Developing a facile and low-cost method to fabricate microfluidic chips could stimulate the progress of the applications of those chips. Here, we present an easy method for fabrication of a complete PDMS (Polydimethylsiloxane) microfluidic chip used for ion and protein enrichment. The method consists of three main fabrication steps: PDMS microchannels ablation by co2 laser, nation membrane deposition, and oxygen plasma assist bonding under pressure. To fabricate a desired microchannel, the laser ablation parameters, containing laser power and ablation speed, were analyzed. The parameters for oxygen plasma assist bonding were also investigated to improve the bonding quality of the chips (low dimension loss and high bonding strength). The following Rhodamine B enrichment tests demonstrate that the presented method allows fabrication of microfluidic chips with precise dimensions and leakage free.

Influence of Ce, Nd, Eu and Tm Dopants on the Properties of InSe Monolayer: A First-Principles Study

Doping of foreign atoms may substantially alter the properties of the host materials, in particular low-dimension materials, leading to many potential functional applications. Here, we perform density functional theory calculations of two-dimensional InSe materials with substitutional doping of lanthanide atoms (Ce, Nd, Eu, Tm) and investigate systematically their structural, magnetic, electronic and optical properties. The calculated formation energy shows that the substitutional doping of these lanthanide atoms is feasible in the InSe monolayer, and such doping is more favorable under Se-rich than In-rich conditions. As for the structure, doping of lanthanide atoms induces visible outward movement of the lanthanide atom and its surrounding Se atoms. The calculated total magnetic moments are 0.973, 2.948, 7.528 and 1.945 μB for the Ce-, Nd-, Eu-, and Tm-doped systems, respectively, which are mainly derived from lanthanide atoms. Further band structure calculations reveal that the Ce-doped InSe monolayer has n-type conductivity, while the Nd-doped InSe monolayer has p-type conductivity. The Eu- and Tm-doped systems are found to be diluted magnetic semiconductors. The calculated optical response of absorption in the four doping cases shows redshift to lower energy within the infrared range compared with the host InSe monolayer. These findings suggest that doping of lanthanide atoms may open up a new way of manipulating functionalities of InSe materials for low-dimension optoelectronics and spintronics applications.

S-Box Design Based on 2D Multiple Collapse Chaotic Map and Their Application in Image Encryption

As an essential part of an encryption system, the performance of a chaotic map is critical for system security. However, there are many defects for the existing chaotic maps. The low-dimension (LD) ones are easily predicted and are vulnerable to be attacked, while high-dimension (HD) ones have a low iteration speed. In this paper, a 2D multiple collapse chaotic map (2D-MCCM) was designed, which had a wide chaos interval, a high complexity, and a high iteration speed. Then, a new chaotic S-box was constructed based on 2D-MCCM, and a diffusion method was designed based on the S-box, which improved security and efficiency. Based on these, a new image encryption algorithm was proposed. Performance analysis showed that the encryption algorithm had high security to resist all kinds of attacks easily.

How to make traversable wormholes: eternal AdS4 wormholes from coupled CFT’s

We construct an eternal traversable wormhole connecting two asymptotically AdS4 regions. The wormhole is dual to the ground state of a system of two identical holographic CFT’s coupled via a single low-dimension operator. The coupling between the two CFT’s leads to negative null energy in the bulk, which supports a static traversable wormhole. As the ground state of a simple Hamiltonian, it may be possible to make these wormholes in the lab or on a quantum computer.