On the colorability of bi-hypergraphs

A {\it mixed hypergraph} ${\cal H}=({\cal V},{\cal C},{\cal D})$ consists of the vertex set ${\cal V}$ and two families of subsets of $2^{{\cal V}}$: the family ${\cal C}$ of co-edges and the family ${\cal D}$ of edges. ${\cal H}$ is said to be colorable if there is a mapping $f$ from ${\cal V}$ to the set of positive integers such that $|\{f(v):v\in e\}|<|e|$ for each $e\in {\cal C}$ and $|\{f(v):v\in e\}|>1$ for each $e\in {\cal D}$. There exist mixed hypergraphs which are uncolorable, and quite little about these mixed hypergraphs is known. A mixed hypergraph is called a bi-hypergraph if its co-edge set and edge set are the same. In this article, we first apply Lov\'asz local lemma to show that any $r$-uniform bi-hypergraph with $r\ge 4$ is colorable if every edge is incident to less than $(r-1)^{r-1}e^{-1}-1$ other edges, where $e$ is the base of natural logarithms. Then, we show that among all the uncolorable $3$-uniform bi-hypergraphs, the smallest size of a minimal one is ten, which answers a question raised by Tuza and Voloshin in 2000. As an extension, we provide a minimal uncolorable $3$-uniform bi-hypergraph of order $n$ and size at most $\frac{7n}3-4$ for every $n\ge 6$.Comment: 19 pages, 4 figure

3D Dynamic Motion Planning for Robot-Assisted Cannula Flexible Needle Insertion into Soft Tissue

In robot-assisted needle-based medical procedures, insertion motion planning is a crucial aspect. 3D dynamic motion planning for a cannula flexible needle is challenging with regard to the nonholonomic motion of the needle tip, the presence of anatomic obstacles or sensitive organs in the needle path, as well as uncertainties due to the dynamic environment caused by the movements and deformations of the organs. The kinematics of the cannula flexible needle is calculated in this paper. Based on a rapid and robust static motion planning algorithm, referred to as greedy heuristic and reachability-guided rapidly-exploring random trees, a 3D dynamic motion planner is developed by using replanning. Aiming at the large detour problem, the convergence problem and the accuracy problem that replanning encounters, three novel strategies are proposed and integrated into the conventional replanning algorithm. Comparisons are made between algorithms with and without the strategies to verify their validity. Simulations showed that the proposed algorithm can overcome the above-noted problems to realize real-time replanning in a 3D dynamic environment, which is appropriate for intraoperative planning. © 2016 Author

Research on computer information processing and security technology based on big data technology

with the continuous development of China’s Internet industry, computer information processing and security technology has ushered in new development opportunities. In this process, there are also some challenges that we need to pay full attention to, so as to help the further development of computer information processing and security technology. In order to further improve the comprehensive level of China’s computer information processing and security technology, we should continue to deepen the research on big data technology and better integrate it with computer information processing and security technology, so as to promote the further development of computer information processing and security technology and highlight the practical application advantages of big data technology. In view of this, this paper will analyze the computer information processing and security technology based on big data technology, and put forward some strategies for your reference

Application of signal processing system in electronic information practice

the signal processing system can be widely used in the fields of network, electronics, machinery, communication and computer, providing technical s upport for the upgrading of teaching platform and system, and the optimization of electronic information practice mode. In the era of “digital signal processing” technology gradually replacing the traditional “analog signal processing” technology, developers can optimize the practice mode of electronic information based on the application advantages of digital signal processing system, add some practical functions for it, improve the friendliness of the operation interface, and make it better meet the relevant use needs. Based on this, this paper fi rst analyzes the application advantages and necessity of digital signal processing system, and then discusses its overall structure and application mode, in order to provide reference for the related technical work and R & D activities

On the development of computer network management technology in the new era

with the development of science and technology in China, network technology has been used in various fi elds of society, and plays an important role. With the development of the times, it has gradually become an important part of people’s life and production process. However, in the new era, there are still many problems that are diffi cult to solve in the process of computer network management in China. In view of this, this paper analyzes the development of computer network management technology in the new era in detail, hoping to provide some valuable references for teachers and friends

Teaching reform of computer network security course in Colleges and Universities

Under the background of the rapid development of information technology, the application scope of e-commerce has been continuously improved, which also improves the application degree of computer. In order to conform to the characteristics of the development of the times, colleges and universities should strengthen the personnel training work, and cultivate students with strong quality and ability, and master systematic and comprehensive computer network knowledge in the new era. Therefore, teachers need to teach students the basic concepts, theories and technical methods of network security knowledge to ensure that they meet the characteristics and requirements of higher education. Based on this, this paper analyzes and studies the teaching reform of computer network security course in Colleges and universities, expounds the necessity of teaching reform of computer network security course in Colleges and universities, analyzes the characteristics of computer network security classroom in Colleges and universities, and puts forward the teaching reform strategies of computer network security course in colleges and universities on this basis, for reference

Modulation of CXCR4, CXCL12, and Tumor Cell Invasion Potential In Vitro by Phytochemicals.

CXCR4 is a chemokine receptor frequently overexpressed on primary tumor cells. Organs to which these cancers metastasize secrete CXCL12, the unique ligand for CXCR4, which stimulates invasion and metastasis to these sites. Similar to our previous work with the chemoprotective phytochemical, 3,3'-diindolylmethane (DIM), we show here that genistein also downregulates CXCR4 and CXCL12 and subsequently lowers the migratory and invasive potentials of breast and ovarian cancer cells. Moreover, genistein and DIM elicit a significantly greater cumulative effect in lowering CXCR4 and CXCL12 levels than either compound alone. Our data suggest a novel mechanism for the protective effects of phytochemicals against cancer progression and indicate that in combination, these compounds may prove even more efficacious