Predicting temporal centrality in Opportunistic Mobile Social Networks based on social behavior of people

Predicting the centrality of nodes is a significant problem for different applications in Opportunistic Mobile Social Networks (OMSNs). However, when calculating such metrics, current studies focused on analyzing static networks that do not change over time or using aggregated contact information over a period of time. Furthermore, the centrality measured in the past is not verified whether it is useful as a predictor for the future. In this paper, in order to capture the dynamic behavior of people, we focus on predicting nodes’ future centrality (importance) from the temporal perspective using real mobility traces in OMSNs. Three important centrality metrics, namely betweenness, closeness, and degree centrality, are considered. Through real trace-driven simulations, we find that nodes’ future centrality is highly predictable due to natural social behavior of people. Then, based on the observations in the simulation, we design several reasonable prediction methods to predict nodes’ future temporal centrality. Finally, extensive real trace-driven simulations are conducted to evaluate the performance of our proposed methods. The results show that the Recent Weighted Average Method performs best in the MIT Reality trace, and the recent Uniform Average Method performs best in the Infocom 06 trace. Furthermore, we also evaluate the impact of parameters m and w on the performance of the proposed methods and find proper values of different parameters for each proposed method at the same time.     

浅谈信息技术与数学学科的整合

信息技术的发展,使人们的学习和交流打破了过去的时空界限,为人类能力的提高和发挥作用带来了新的空间。通过信息技术与数学学科的整合,让数学更贴近生活,突破教学重点难点,提高了学生的发散性思维能力,让我们看到信息技术在教学中的重要性。     

Impact of Knowledge Representations on Problem-Oriented Learning in Online Environments

The objective of this study was to investigate the impact of knowledge representations on problem-oriented learning in online learning environments. The study compared the impact of knowledge map representation with traditional hierarchical representation with regard to learning memory and problem-solving performance. Twenty-nine students participated in an experiment in which they studied online materials with the goal of solving two programming problems (simple and complex). It was found that participants who used the hierarchical representation read in the depth-first sequence, whereas participants who used the knowledge map representation read in a sequence reflecting the system running mechanism implied by the graphical representation. In addition, participants who used the knowledge map representation had better memory of the learning content, especially about relations between knowledge nodes. When solving the complex problem, participants who used the knowledge map representation made a deeper analysis of the problem and had better problem-solving performance. These results were not significant in the simple problem-solving task.     

Laminated paper-based analytical devices (LPAD): fabrication, characterization, and assays

Paper-based microfluidic devices have recently garnered an increasing interest in the literature. The majority of these devices were produced by patterning hydrophobic zones in hydrophilic paper via photoresist or wax. Others were created by cutting paper using a laser. Here, we present a fabrication method for producing devices by simple craft-cutting and lamination, in a way similar to making an identification (ID) card. The method employs a digital craft cutter and roll laminator to produce laminated paper-based analytical devices (LPAD). Lamination with a plastic backing provides the mechanical strength for a paper device. The approach of using a craft cutter and laminator makes it possible to rapid-prototype LPAD with no more difficulty than producing a typical ID card, at very low cost. Devices constructed using this method have been exploited for simultaneous detection of bovine serum albumin (BSA) and glucose in synthetic urine with colorimetric assays. Both BSA and glucose are detectable at clinically relevant concentrations, with the detection limit at 2.5 μM for BSA and 0.5 mM for glucose.     

A novel micro-fluidic biosensor for the rapid and sequence-specific detection of DNA with electrophoretic driving mode and laser-induced fluorescence detector

A novel DNA biosensor, which combines the merits of micro-fluidic chips, the electrophoretic driving mode, paramagnetic beads amplification, and laser-induced fluorescence detection was developed for the rapid and sequence-specific detection of DNA in this study. The proposed DNA biosensor has much higher discrimination ability for the detection of single-base mismatch and much stronger resistibility to the complex matrixes of real samples in comparison with previous biosensors. These features, as well as its ease of fabrication (the fabrication of the sensor takes only 10 min except the fabrication of micro-fluidic chip), operation convenience, stability, better re-usability (micro-fluidic chip can be reused without any extra treatment) and short analysis time (one determination only takes 15 min), make it a promising alternative to rapid detection of DNA in clinical diagnosis. With the help of the biosensor, we successfully determined DNA, which related to oral cancer, in a saliva sample without any pre-separation or dilution with a detection limit of 4.2 × 10^?11 M and a relative standard deviation (n = 5) <5 %. The success in the present biosensor served as a significant step toward the practical application of the biosensor in clinical diagnosis.     

A method of identifying chronic stress by EEG

There are a lot of studies on chronic stress assessment applying psychology instruments or hormones analysis. However, there are only few studies using electroencephalogram (EEG), which is a non-invasive method providing objective inspection on brain functioning. In this paper, we analyzed overall complexity and spectrum power of certain EEG bands (theta, alpha and beta) collected from two groups of human subjects—high stress versus moderate stress at prefrontal sites (Fp1, Fp2 and Fpz). The results showed that the differences of nonlinear features (C0, LZC, D2, L1 and RE) and linear features (power and alpha asymmetry score) between two groups are significant. C0, LZC and D2 significantly increased in stress group at Fp1 and Fp2, while L1 and RE significantly decreased. And those with chronic stress have higher left prefrontal power. Finally, we suggest that it may be effective to discriminate the high-stress people from moderate-stress people by EEG.     

机械加工过程中的振动及控制方法研究

机械加工中的振动对于加工质量和生产效率都有很大影响,须采取措施控制振动.本文首先简要介绍了机械加工过程中的振动问题的危害,然后详细介绍了消除或减弱机械加工过程中的振动的具体方法和策略.     

MSN,就像QQ一样用网盘

除了QQ之外,相信很多朋友也会同时使用Windows Live Messenger（以下简称MSN）,可惜MSN并没有提 供类似QQ的网络硬盘、文件中转站的功能,每次需要临时存储文件都要另想他法,例如25GB的SkyDrive服务, 但从网页上访问SkyDrive相当繁琐。     

WPS特色插件吉祥三宝

WPS功能已经够全了,但是大家的需求是无止境的,一些特殊任务就交给WPS的插件来处理吧,通过插件让自己的山PS与众不同。