SENP2 Regulates Hepatocellular Carcinoma Cell Growth by Modulating the Stability of β-catenin

Shen, Huo-Jian,Zhu, Hong-Yi,Yang, Chao,Ji, Fu Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.8

SUMOylation has emerged as an important post-translational modification that modulates the localization, stability and activity of a broad spectrum of proteins. A dynamic process, it can be reversed by a family of SUMO-specific proteases (SENPs). However, the biological roles of SENPs in mammalian development and pathogenesis remain largely elusive. Here, we demonstrated that SENP2 plays a critical role in the control of hepatocellular carcinoma cell growth. SENP2 was found to be down-regulated in hepatocellular carcinoma (HCC) tissues and over-expression suppressed the growth and colony formation of HCC cells. In contrast, silencing of SENP2 by siRNAs promoted cancer cell growth. We further found that stability of ${\beta}$-catenin was markedly decreased when SENP2 was over-expressed. Interestingly, the decrease was dependent on the de-SUMOylation activity of SENP2, because over-expression of a SENP2 catalytic mutant form had no obviously effects on ${\beta}$-catenin. Our results suggest that SENP2 might play a role in hepatocellular carcinoma cell growth control by modulating the stability of ${\beta}$-catenin.

Routing Protocols in Delay Tolerant Networks

Jian Shen,Sangman Moh,Ilyong Chung 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

Delay Tolerant Networks (DTNs) are a class of emerging networks that experience frequent and longduration partitions. Compared with the conventional networks, the distinguished feature is that there is no endto-end connectivity between source and destination. The network topology may change dynamically and randomly, and the non-existence of an end-to-end path poses a number of challenges in routing in DTNs. In this paper, we survey the state-of-the-art routing protocols and give a comparison of them with respect to the important challenging issues in DTNs. The routing protocols are classified into two categories based on which property is used to find the destination: flooding families and forwarding families. The pros and cons as well as performance are disccused and compared for the routing protocols.

Flux Sliding-mode Observer Design for Sensorless Control of Dual Three-phase Interior Permanent Magnet Synchronous Motor

Shen, Jian-Qing,Yuan, Lei,Chen, Ming-Liang,Xie, Zhen The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

A novel equivalent flux sliding-mode observer (SMO) is proposed for dual three-phase interior permanent magnet synchronous motor (DT-IPMSM) drive system in this paper. The DT-IPMSM has two sets of Y-connected stator three-phase windings spatially shifted by 30 electrical degrees. In this method, the sensorless drive system employs a flux SMO with soft phase-locked loop method for rotor speed and position estimation, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Meanwhile, to get the regulator parameters of current control, the inner current loop is realized using a decoupling and diagonal internal model control algorithm. Experiment results of 2MW-level DT-IPMSM drives system show that the proposed method has good dynamic and static performances.

Location Based Routing Protocol for Delay Tolerant Networks

Jian Shen,Sangman Moh,Ilyong Chung 한국멀티미디어학회 2009 한국멀티미디어학회 학술발표논문집 Vol.2009 No.1

Delay Tolerant Networks (DTNs) are a class of emerging networks that experience frequent and long-duration partitions. In this paper, we present a location based routing protocol (LPR) for DTNs, which utilizes the location of nodes to deliver a message from source to destination. A node can get the location by receiving beacon packets periodically from anchor nodes and referring to received signal strength indicator (RSSI) for the beacon. This new routing protocol employs a scheme named transmission scheme, which take advantages of the nodes' information of the location to transmit the message and store the message into buffer space, respectively.

A Priority Routing Protocol Based on Location and Moving Direction in Delay Tolerant Networks

SHEN, Jian,MOH, Sangman,CHUNG, Ilyong The Institute of Electronics, Information and Comm 2010 IEICE transactions on information and systems Vol.93 No.10

<P>Delay Tolerant Networks (DTNs) are a class of emerging networks that experience frequent and long-duration partitions. Delay is inevitable in DTNs, so ensuring the validity and reliability of the message transmission and making better use of buffer space are more important than concentrating on how to decrease the delay. In this paper, we present a novel routing protocol named <I>Location and Direction Aware Priority Routing (LDPR)</I> for DTNs, which utilizes the location and moving direction of nodes to deliver a message from source to destination. A node can get its location and moving direction information by receiving beacon packets periodically from anchor nodes and referring to received signal strength indicator (RSSI) for the beacon. LDPR contains two schemes named transmission scheme and drop scheme, which take advantage of the nodes' information of the location and moving direction to transmit the message and store the message into buffer space, respectively. Each message, in addition, is branded a certain priority according to the message's attributes (e.g. importance, validity, security and so on). The message priority decides the transmission order when delivering the message and the dropping sequence when the buffer is full. Simulation results show that the proposed LDPR protocol outperforms epidemic routing (EPI) protocol, prioritized epidemic routing (PREP) protocol, and DTN hierarchical routing (DHR) protocol in terms of packet delivery ratio, normalized routing overhead and average end-to-end delay. It is worth noting that LDPR doesn't need infinite buffer size to ensure the packet delivery ratio as in EPI. In particular, even though the buffer size is only 50, the packet delivery ratio of LDPR can still reach 93.9%, which can satisfy general communication demand. We expect LDPR to be of greater value than other existing solutions in highly disconnected and mobile networks.</P>

Buffer Scheme Optimization of Epidemic Routing in Delay Tolerant Networks

Jian Shen,모상만,Ilyong Chung,Xingming Sun 한국통신학회 2014 Journal of communications and networks Vol.16 No.6

In delay tolerant networks (DTNs), delay is inevitable;thus, making better use of buffer space to maximize the packetdelivery rate is more important than delay reduction. In DTNs,epidemic routing is a well-known routing protocol. However, epidemicrouting is very sensitive to buffer size. Once the buffer sizein nodes is insufficient, the performance of epidemic routing willbe drastically reduced. In this paper, we propose a buffer schemeto optimize the performance of epidemic routing on the basis of theLagrangian and dual problem models. By using the proposed optimalbuffer scheme, the packet delivery rate in epidemic routing isconsiderably improved. Our simulation results show that epidemicrouting with the proposed optimal buffer scheme outperforms theoriginal epidemic routing in terms of packet delivery rate and averageend-to-end delay. It is worth noting that the improved epidemicrouting needs much less buffer size compared to that of the originalepidemic routing for ensuring the same packet delivery rate. Inparticular, even though the buffer size is very small (e.g., 50), thepacket delivery rate in epidemic routing with the proposed optimalbuffer scheme is still 95.8%, which can satisfy general communicationdemand.

Enhanced Secure Sensor Association and Key Management in Wireless Body Area Networks

Jian Shen,Haowen Tan,모상만,정일용,Qi Liu,Xingming Sun 한국통신학회 2015 Journal of communications and networks Vol.17 No.5

Body area networks (BANs) have emerged as an enabling technique for e-healthcare systems, which can be used to continuously and remotely monitor patients’ health. In BANs, the data of a patient’s vital body functions and movements can be collected by small wearable or implantable sensors and sent using shortrange wireless communication techniques. Due to the shared wireless medium between the sensors in BANs, it may be possible to have malicious attacks on e-healthcare systems. The security and privacy issues of BANs are becoming more and more important. To provide secure and correct association of a group of sensors with a patient and satisfy the requirements of data confidentiality and integrity in BANs, we propose a novel enhanced secure sensor association and key management protocol based on elliptic curve cryptography and hash chains. The authentication procedure and group key generation are very simple and efficient. Therefore, our protocol can be easily implemented in the power and resource constrained sensor nodes in BANs. From a comparison of results, furthermore, we can conclude that the proposed protocol dramatically reduces the computation and communication cost for the authentication and key derivation compared with previous protocols. We believe that our protocol is attractive in the application of BANs.

Experimental study on cold-formed lipped channel stub columns reinforced by steel bars or steel strips

Jian-Feng Chen,Ming-Qi Chen,Yong-Kang Shen,Jian-Hua Shao,Xin-Xin Yang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.3

In this paper, the axial compressive properties of cold-formed steel lipped channel stub columns strengthened by rebars or steel strips are experimentally studied. The experiment included two sections. A kind of columns with local buckling is reinforced longitudinally by steel strips at the web. The other is the columns with distorted buckling, which is reinforced longitudinally by steel bars at the curling edge. The failure mode, deformation characteristics, ultimate bearing capacity and load displacement curve of the specimen are obtained through the experiment. On the basis of the experiment, the calculation results of theoretical axial bearing capacity of cold-formed steel lipped channel stub columns in Chinese, North American and Australian code are compared and analyzed. Research indicates: First, the cold-formed steel lipped channel stub columns strengthened by steel bars or steel strips can effectively improve the compressive bearing capacity of the specimen. Secondly, when the initial stress ratio of specimen is less than 0.3, the reinforcement effect is ideal. Thirdly, the three standards don’t stipulate the calculation of theoretical bearing capacity of the specimen strengthened after loading, so there is a large deviation between the theoretical calculation value and the test value.

Enhanced Key Management Protocol in Body Area Networks

Jian Shen,Sangman Moh,Ilyong Chung 한국멀티미디어학회 2010 한국멀티미디어학회 학술발표논문집 Vol.2010 No.2

Body Area Networks (BANs) have emerged as an enabling technique for e-healthcare systems, in which the data of a patient’ vital body parameters and movements can be collected by small wearable or implantable sensors and communicated using short-range wireless communication techniques. Due to the shared wireless medium between the sensors in BANs, adversaries can launch various attacks on the e-healthcare systems. The security and privacy issues of BANs are getting more and more important. To provide secure and correct association of a group of sensors with a patient and satisfy the requirements of data confidentiality and integrity in BANs, we propose a novel enhanced key management protocol based on elliptic curve cryptography (ECC) and hash chains. The authentication procedure and group key generation are very simple and efficient. Therefore, our protocol can be easily implemented into the power and resource constrained sensor nodes in BANs. From the comparison results, furthermore, we can conclude that the proposed protocol dramatically reduces the computation and communication cost for the authentication and key derivation compared with the previous protocols. We believe that our protocol is attractive to the applications of BANs.

A Comparative Survey on Routing Protocols Using Directional Antennas in Ad Hoc Networks

Jian Shen,Dongmin Choi,Sangman Moh,Ilyong Chung 한국멀티미디어학회 2010 한국멀티미디어학회 학술발표논문집 Vol.2010 No.1

Directional antennas have the potential to provide a fundamental breakthrough in ad hoc network capacity. Omni-directional nature of transmission restricts the network capacity, where distribution of energy in all directions other than the intended direction of the destination node not only generated unnecessary interference to other neighboring nodes but also decreases the potential range of transmission. Directional antenna systems are increasingly being recognized as a powerful way of increasing the capacity, connectivity, and covertness of MANETs. In this paper, we survey the state-of-the-art routing protocols and give a comparison result of them with respect to the important challenging issues. We study the advantages and disadvantages of the routing protocols using directional antenna and also highlight performance issues of each routing technique. At the end, an explicit comparison table is presented and discussed.