Lineage of non-cranial neural crest cell in the dental mesenchyme: using a lacZ reporter gene during early tooth development

The tooth is one of the ectodermal organs controlled by reciprocal interactions between the epithelium and the mesenchyme. Mesenchymal cells in the developing tooth, so-called dental mesenchymal cells, are derived from two different origins: the cranial neural crest (CNC) and the non-CNC. These CNC-derived cells migrate, proliferate and differentiate into odontoblasts, cementoblasts, fibroblasts, osteoblasts and chondroblasts. Tooth germs of wild-type mice were transplanted into the kidney of adult lacZ-transgenic mice. After 1 week of transplantation, a few lacZ-expressing cells and many red blood cells were found near or inside the blood vessels in the pulp of wild-type tooth germs. This result shows that circulating cells of the adult host could invade the dental pulp during tooth development, through the blood vessels, and be a part of dental pulp tissue. Therefore, it can be suggested that these circulating progenitor cells could be the origin of non-CNC-derived cells in tooth germ and their migration pathways would be the blood vessels invading the dental pulp during tooth development. If variations of this experiment were suitably adjusted, such as the embryonic stage of the tooth germ, duration of transplantation, etc., this transplantation experiment using adult lacZ-transgenic mice could be a good system to reveal the origin and migration pathway of cells in developing organs as well as in dental mesenchymal cells.     

On Striping Traffic over Multiple IEEE 802.11(b) Wireless Channels

Due to interference, path loss, multipath fading, background noise, and many other factors, wireless communication normally cannot provide a wireless link with both a high data rate and a long transmission range. To address this problem, striping network traffic in parallel over multiple lower-data-rate but longer-transmission-range wireless channels may be used. In this paper, we propose a new striping method and evaluate its performances over multiple IEEE 802.11(b) channels under various conditions. Our extensive simulation results show that this method is quite effective for such an application. S.Y. Wang is an Associate Professor of the Department of Computer Science and Information Engineering at National Chiao Tung University, Taiwan. He received his Master and Ph.D. degree in computer science from Harvard University in 1997 and 1999, respectively. His research interests include wireless networks, Internet technologies, network simulations, and operating systems. He is the author of the NCTUns 2.0 network simulator and emulator, which is being widely used by network and communication researchers. More information about the tool is available at http://NSL.csie.nctu.edu.tw/nctuns.html. C.H. Hwang received his master degree in computer science from NCTU in 2002 and currently is working for a network company. C.L. Chou currently is a third-year Ph.D. student at the Department of Computer Science and Information Engineering, National Chiao TungUniversity (NCTU), Taiwan. He received his master degree in computer science from NCTU in 2002.     

A power-driven multiplication instruction-set design method for ASIPs

This paper presents a novel power-driven multiplication instruction-set design method for application-specific instruction-set processors (ASIPs). Based on a dual-and-configurable-multiplier structure, our proposed method devises a multiplication instruction set for low-power ASIPs. Our method exploits the execution sequences of multiplication instructions and effective bit widths of variables to reduce power consumed by redundant multiplication bits while minimizing the multiplication execution time. Experimental results on a set of DSP programs demonstrate that our proposed method achieves significant power reduction (up to 18.53%) and execution time improvement (up to 10.43%) with 18% area overhead.     

Curved Projection Integral Imaging Using an Additional Large‐Aperture Convex Lens for Viewing Angle Improvement

In this paper, we propose a curved projection integral imaging system to improve the horizontal and vertical viewing angles. The proposed system can be easily implemented by additional use of a large‐aperture convex lens in conventional projection integral imaging. To obtain the simultaneous display of 3D images through real and virtual image fields, we propose a computer‐generated pickup method based on ray optics and elemental images, which are synthesized for the proposed system. To show the feasibility of the proposed system, preliminary experiments are carried out. Experimental results indicate that our system improves the viewing angle and displays 3D images simultaneously in real and virtual image fields.     

基于最优颜色通道的图像拼接检测

针对不同颜色通道影响噪声估计值的问题,文中提出了基于最优颜色通道的图像拼接检测方法。利用主成分分析法在最优颜色通道上进行噪声值估计,根据噪声值大小利用K-means聚类法进行聚类。聚类结果分为可疑部分和非可疑部分两大类,通过两阶段策略进一步定位出篡改区域。该方法在原始区域与拼接区域噪声值相差较大或较小时均有效,并且能够定位出拼接区域。实验证明,所提方法与现有方法相比取得了良好的检测效果,且性能优于现有方法。     

Data retention characteristics of MANOS-type flash memory device with different metal gates at various levels of charge injection

We investigated the impact of charge injection and metal gates (Al and Pt) on the data retention characteristics of metal–alumina–nitride–oxide–silicon (MANOS) devices for NAND flash memory application. Through the theoretical and experimental results, the highly injected charge (ΔV_TH) could cause the band bending of Al₂O₃, which reduced the tunneling distance across Al₂O₃. Thus, the dominant charge loss path is not only toward SiO₂ but also toward Al₂O₃ direction. Compared to low-metal work function (Ф_M), ONA stack with high-Ф_M showed better data retention characteristics, even if ΔV_TH is high. This could be explained by Fermi level alignment for different Ф_M, which results in the reduction of electric field across the Al₂O₃ compensated by the ΔФ_M (Ф_Pt ? Ф_Al).     

A Reliable Multicast Routing Protocol Based on Recovery Points and FEC in Mobile Ad-hoc Networks

Multicasting is an essential service for mobile ad-hoc networks. A major challenge for multicasting in mobile ad-hoc networks (MANETs) is the unstable forwarding path. This work presents a reliable multicasting protocol for mobile ad-hoc networks. A virtual backbone is used as a shared structure for multiple sessions. A lost packet recovery scheme is developed for reliable packet transmission, called the Recovery Point (RP) scheme. The RP scheme maintains the data packets received from the source for recovering lost packets for its downstream RPs. In addition, we combine the Forward Error Correction (FEC) technology with our RP scheme to enhance the reliability of our RP scheme. A mergence scheme for RP is also proposed to avoid excessive control overhead. Our RP and FEC based scheme can be used to improve the reliability and efficiency of the traditional non-acknowledged multicasting approach. Experiments were conducted to evaluate the proposed multicasting scheme. The results demonstrate that our scheme outperforms other schemes in terms of packet delivery ratio and multicast efficiency. Furthermore, the simulation results also demonstrate that our approach is stable in networks with high mobility.

Design and evaluation of inter‐bandwidth broker signaling

Bandwidth brokers (BBs) have been proposed for providing end‐to‐end quality of services (QoS) in differentiated services (Diffserv) networks. As a single entity in each domain, a BB aims at performing both intra‐ and inter‐domain resource management on behalf of its domain. There have been plenty of BB studies for intra‐domain resource management. However, how a BB can perform inter‐domain resource management in a scalable and deployable manner is still an open issue. In this work, we present the design, implementation and evaluation of an inter‐BB communication protocol that is used by each BB to communicate with its neighboring BBs for inter‐domain QoS resource management. The proposed model uses a destination‐based aggregation scheme in which reservations are aggregated as they merge through the destination region. The destination‐based aggregation improves inter‐domain state and signaling scalability. The protocol also performs traffic engineering to increase inter‐domain resource utilization. The implementation and simulation results verify the achievements of our model. Copyright © 2008 John Wiley & Sons, Ltd.     

Mucoadhesive Phenolic Pectin Hydrogels for Saliva Substitute and Oral Patch

Oral disease is one of the most common conditions worldwide, negatively affecting general health, reducing the quality of life, and often developing into systemic illness. However, the design of therapeutic agents for oral diseases is challenging due to various unique features of the oral cavity, including its wet and dynamic environment and curved shape. Herein, the development of highly biocompatible mucoadhesive functional hydrogels for oral applications is reported, generated by introducing bio-inspired phenolic moieties into a pectin polymer. Pyrogallol-functionalized pectin (Pec-PG) can be crosslinked in situ via autoxidation without chemical agents and readily fabricated as various formulations. Sprayable Pec-PG hydrogel exhibits strong mucoadhesion and outstanding hydration ability ex vivo and in vivo, thus displaying significant potential as a novel saliva substitute for dry mouth. The authors further show that topical application of mucoadhesive Pec-PG patches pre-loaded with corticosteroid significantly promotes the repair of diabetic oral ulcer tissue via prolonged drug release, free radical scavenging, and physical barrier effects. Moreover, similar applications for oral ulcer treatment using a pectin hydrogel modified with catechol (Pec-CA), another phenolic moiety are demonstrated. Together, these findings suggest that mucoadhesive phenolic pectin derivatives can provide highly biocompatible, convenient, and effective hydrogel platforms for treating oral diseases.     

双重JPEG压缩图像篡改区域检测与定位

对JPEG(joint photographic experts group)图像实施篡改往往会产生双重JPEG(double JPEG,DJPE) 压缩痕迹,分析该痕迹有助于揭示图像压缩历史并实现篡改区域定位。现有算法在图像尺寸较小和质量因子(quality factor,QF) 较低的时候性能不佳,对两个QF的组合情况存在限制。本文提出了一种端到端的混合QF双重JPEG压缩图像取证网络,命名为DJPEGNet。首先,使用预处理层从图像头文件中提取表征压缩历史信息的量化表 (quantization table,Qtable) 特征,将图像从空域转换至DCT(discrete cosine transform)域构造统计直方图特征。然后,将两个特征输入到由深度可分离卷积和残差结构堆叠而成的主体结构,输出二分类结果。最后,使用滑动窗口算法自动定位篡改区域并绘制概率分布图。实验结果表明,在使用不同Qtable集生成的小尺寸数据集上,DJPEGNet所有指标均优于现有最先进的算法,其中ACC提高了1.78%,TPR提升了2.00%,TNR提升了1.60%。