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Sample records for cd-1 reliable multicast

  1. The reliable multicast protocol application programming interface

    Science.gov (United States)

    Montgomery , Todd; Whetten, Brian

    1995-01-01

    The Application Programming Interface for the Berkeley/WVU implementation of the Reliable Multicast Protocol is described. This transport layer protocol is implemented as a user library that applications and software buses link against.

  2. Modeling of reliable multicasting services

    DEFF Research Database (Denmark)

    Barkauskaite, Monika; Zhang, Jiang; Wessing, Henrik

    2010-01-01

    This paper addresses network survivability for Multicast transport over MPLS-TP ring topology networks. Protection mechanisms standardized for unicast are not fully suitable for multicast point-to-multipoint transmission and multicast schemes are not standardized yet. Therefore, this paper...... investigates one of the proficient protection schemes and uses OPNET Modeler for analyzing and designing networks with the chosen protection method. For failure detection and protection switching initiation, the OAM (Operation, Administration and Maintenance) functions will be added to the system model. From...

  3. Reliable multicasting in the Xpress Transport Protocol

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, J.W. [Concordia Univ., Montreal, PQ (Canada); Catrina, O. [Polytehnica Univ., Bucharest (Romania); Fenton, J. [Mentat, Inc., Los Angeles, CA (United States); Strayer, W.T. [Sandia National Labs., Livermore, CA (United States)

    1996-12-01

    The Xpress Transport Protocol (XTP) is designed to meet the needs of distributed, real-time, and multimedia systems. This paper describes the genesis of recent improvements to XTP that provide mechanisms for reliable management of multicast groups, and gives details of the mechanisms used.

  4. Reliable adaptive multicast protocol in wireless Ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    Sun Baolin; Li Layuan

    2006-01-01

    In wireless ad hoc network environments, every link is wireless and every node is mobile. Those features make data lost easily as well as multicasting inefficient and unreliable. Moreover, Efficient and reliable multicast in wireless ad hoc network is a difficult issue. It is a major challenge to transmission delays and packet losses due to link changes of a multicast tree at the provision of high delivery ratio for each packet transmission in wireless ad hoc network environment.In this paper, we propose and evaluate Reliable Adaptive Multicast Protocol (RAMP) based on a relay node concept. Relay nodes are placed along the multicast tree. Data recovery is done between relay nodes. RAMP supports a reliable multicasting suitable for mobile ad hoc network by reducing the number of packet retransmissions. We compare RAMP with SRM (Scalable Reliable Multicast). Simulation results show that the RAMP has high delivery ratio and low end-to-end delay for packet transmission.

  5. Fault recovery in the reliable multicast protocol

    Science.gov (United States)

    Callahan, John R.; Montgomery, Todd L.; Whetten, Brian

    1995-01-01

    The Reliable Multicast Protocol (RMP) provides a unique, group-based model for distributed programs that need to handle reconfiguration events at the application layer. This model, called membership views, provides an abstraction in which events such as site failures, network partitions, and normal join-leave events are viewed as group reformations. RMP provides access to this model through an application programming interface (API) that notifies an application when a group is reformed as the result of a some event. RMP provides applications with reliable delivery of messages using an underlying IP Multicast (12, 5) media to other group members in a distributed environment even in the case of reformations. A distributed application can use various Quality of Service (QoS) levels provided by RMP to tolerate group reformations. This paper explores the implementation details of the mechanisms in RMP that provide distributed applications with membership view information and fault recovery capabilities.

  6. Dvnamic Retransmission Control for Reliable Mobile Multicast

    Institute of Scientific and Technical Information of China (English)

    LIN Yu(林宇); WU HaiTao(邬海涛); WANG ChongGang(王重钢); CHENG ShiDuan(程时端)

    2003-01-01

    Most existing multicast protocols adopt a static retransmission scheme (unicastor multicast) to retransmit lost packets. In the mobile multicast environment, static multicast re-transmission mode may lead to congestion in the receivers' wireless interfaces, while static unicastmode may result in great network load. Both static unicast and multicast retransmission modeswill cause a performance loss. This paper logically divides the mobile multicast network into fixedand mobile parts, and focuses on the mobile part. Then this paper analyzes the retransmissioncosts when multicast or unicast mode is chosen. Two main parameters are used to compare theirefficiencies: the average air-interface utilization of each receiver and the average network load.Based on the results of analysis, two new algorithms, called NLPA (Network Load Priority Algo-rithm) and AUPA (Air-interface Utilization Priority Algorithm) are presented. Finally, simulationresults conclude that, with proper parameters, both NLPA and AUPA can dynamically alternatebetween unicast and multicast retransmission modes according to the conditions of network andreceiver, and avoid congestion in receivers' wireless interfaces as well as great network load, witha better use of network and terminal resources.

  7. Reliable Multicast Error Recovery Algorithm in Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    Tariq Abdullah

    2012-11-01

    Full Text Available Mobile ad hoc network is an autonomous system of mobile nodes characterized by wireless links. The major challenge in ad hoc networks lies in adapting multicast communication to several environments, where mobility is unlimited and failures are frequent. Reliable multicast delivery requires a multicast message to be received by all mobile nodes in the communication group. The recovery mechanism requires feedback messages from each one of the receivers. In the tree-based recovery protocols, a group of nodes into recovery regions designate a forwarding node per region for retransmitting lost messages. In this study, local error recovery algorithm is applied within these relatively smaller regions, where the repaired packets are retransmitted only to the requested receivers in the local group. These receivers create a sub group from the local group which itself is a subgroup of the global multicast group. By applying local error recovery algorithm, the number of duplicated packets, due to packets retransmission, decreases which lead to improving the system performance. Simulation results demonstrate the scalability of the proposed algorithm in comparison to Source Tree Reliable Multicast (STRM protocol. The algorithm achieved up to 2.33% improvement on the percentage of duplicated packets in stable mobility speed without incurring any further communication or intense computation overhead.

  8. Design, Implementation, and Verification of the Reliable Multicast Protocol. Thesis

    Science.gov (United States)

    Montgomery, Todd L.

    1995-01-01

    This document describes the Reliable Multicast Protocol (RMP) design, first implementation, and formal verification. RMP provides a totally ordered, reliable, atomic multicast service on top of an unreliable multicast datagram service. RMP is fully and symmetrically distributed so that no site bears an undue portion of the communications load. RMP provides a wide range of guarantees, from unreliable delivery to totally ordered delivery, to K-resilient, majority resilient, and totally resilient atomic delivery. These guarantees are selectable on a per message basis. RMP provides many communication options, including virtual synchrony, a publisher/subscriber model of message delivery, a client/server model of delivery, mutually exclusive handlers for messages, and mutually exclusive locks. It has been commonly believed that total ordering of messages can only be achieved at great performance expense. RMP discounts this. The first implementation of RMP has been shown to provide high throughput performance on Local Area Networks (LAN). For two or more destinations a single LAN, RMP provides higher throughput than any other protocol that does not use multicast or broadcast technology. The design, implementation, and verification activities of RMP have occurred concurrently. This has allowed the verification to maintain a high fidelity between design model, implementation model, and the verification model. The restrictions of implementation have influenced the design earlier than in normal sequential approaches. The protocol as a whole has matured smoother by the inclusion of several different perspectives into the product development.

  9. A Novel OBDD-Based Reliability Evaluation Algorithm for Wireless Sensor Networks on the Multicast Model

    Directory of Open Access Journals (Sweden)

    Zongshuai Yan

    2015-01-01

    Full Text Available The two-terminal reliability calculation for wireless sensor networks (WSNs is a #P-hard problem. The reliability calculation of WSNs on the multicast model provides an even worse combinatorial explosion of node states with respect to the calculation of WSNs on the unicast model; many real WSNs require the multicast model to deliver information. This research first provides a formal definition for the WSN on the multicast model. Next, a symbolic OBDD_Multicast algorithm is proposed to evaluate the reliability of WSNs on the multicast model. Furthermore, our research on OBDD_Multicast construction avoids the problem of invalid expansion, which reduces the number of subnetworks by identifying the redundant paths of two adjacent nodes and s-t unconnected paths. Experiments show that the OBDD_Multicast both reduces the complexity of the WSN reliability analysis and has a lower running time than Xing’s OBDD- (ordered binary decision diagram- based algorithm.

  10. Reliable multicast for the Grid: a case study in experimental computer science.

    Science.gov (United States)

    Nekovee, Maziar; Barcellos, Marinho P; Daw, Michael

    2005-08-15

    In its simplest form, multicast communication is the process of sending data packets from a source to multiple destinations in the same logical multicast group. IP multicast allows the efficient transport of data through wide-area networks, and its potentially great value for the Grid has been highlighted recently by a number of research groups. In this paper, we focus on the use of IP multicast in Grid applications, which require high-throughput reliable multicast. These include Grid-enabled computational steering and collaborative visualization applications, and wide-area distributed computing. We describe the results of our extensive evaluation studies of state-of-the-art reliable-multicast protocols, which were performed on the UK's high-speed academic networks. Based on these studies, we examine the ability of current reliable multicast technology to meet the Grid's requirements and discuss future directions.

  11. Connectivity-Based Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs

    Directory of Open Access Journals (Sweden)

    Woo-Yong Choi

    2009-01-01

    Full Text Available We propose the efficient reliable multicast MAC protocol based on the connectivity information among the recipients. Enhancing the BMMM (Batch Mode Multicast MAC protocol, the reliable multicast MAC protocol significantly reduces the RAK (Request for ACK frame transmissions in a reasonable computational time and enhances the MAC performance. By the analytical performance analysis, the throughputs of the BMMM protocol and our proposed MAC protocol are derived. Numerical examples show that our proposed MAC protocol increases the reliable multicast MAC performance for IEEE 802.11 wireless LANs.

  12. Reliable and Energy Efficient Protocol for MANET Multicasting

    Directory of Open Access Journals (Sweden)

    Bander H. AlQarni

    2016-01-01

    Full Text Available A mobile ad hoc network (MANET consists of a self-configured set of portable mobile nodes without any central infrastructure to regulate traffic in the network. These networks present problems such as lack of congestion control, reliability, and energy consumption. In this paper, we present a new model for MANET multicasting called Reliable and Energy Efficient Protocol Depending on Distance and Remaining Energy (REEDDRE. Our proposal is based on a tone system to provide more efficiency and better performance, and it combines solutions over the Medium Access Control (MAC layer. The protocol consists of a new construction method for mobile nodes using a clustering approach that depends on distance and remaining energy to provide more stability and to reduce energy consumption. In addition, we propose an adjustment to the typical multicast flow by adding unicast links between clusters. We further present in our model a technique to provide more reliability based on a busy tone system (RMBTM to reduce excessive control overhead caused by control packets in error recovery. We simulate our proposal using OPNET, and the results show enhancement in terms of reliability, packet delivery ratio (PDR, energy consumption, and throughput.

  13. Analysis and Optimization of Sparse Random Linear Network Coding for Reliable Multicast Services

    DEFF Research Database (Denmark)

    Tassi, Andrea; Chatzigeorgiou, Ioannis; Roetter, Daniel Enrique Lucani

    2016-01-01

    Point-to-multipoint communications are expected to play a pivotal role in next-generation networks. This paper refers to a cellular system transmitting layered multicast services to a multicast group of users. Reliability of communications is ensured via different random linear network coding (RL...... guarantees to predetermined fractions of users. The performance of the proposed optimization framework is then investigated in a LTE-A eMBMS network multicasting H.264/SVC video services....

  14. Verification and validation of a reliable multicast protocol

    Science.gov (United States)

    Callahan, John R.; Montgomery, Todd L.

    1995-01-01

    This paper describes the methods used to specify and implement a complex communications protocol that provides reliable delivery of data in multicast-capable, packet-switching telecommunication networks. The protocol, called the Reliable Multicasting Protocol (RMP), was developed incrementally by two complementary teams using a combination of formal and informal techniques in an attempt to ensure the correctness of the protocol implementation. The first team, called the Design team, initially specified protocol requirements using a variant of SCR requirements tables and implemented a prototype solution. The second team, called the V&V team, developed a state model based on the requirements tables and derived test cases from these tables to exercise the implementation. In a series of iterative steps, the Design team added new functionality to the implementation while the V&V team kept the state model in fidelity with the implementation through testing. Test cases derived from state transition paths in the formal model formed the dialogue between teams during development and served as the vehicles for keeping the model and implementation in fidelity with each other. This paper describes our experiences in developing our process model, details of our approach, and some example problems found during the development of RMP.

  15. Reliable Multicasting for Device-to-Device Radio Underlaying Cellular Networks

    CERN Document Server

    Yang, Wei; Li, Lihua

    2010-01-01

    This paper proposes Leader in Charge (LiC), a reliable multicast architecture for device-to-device (D2D) radio underlaying cellular networks. The multicast-requesting user equipments (UEs) in close proximity form a D2D cluster to receive the multicast packets through cooperation. In addition to receiving the multicast packets from the eNB, UEs share what they received from the multicast on short-range links among UEs, namely the D2D links, to exploit the wireless resources a more efficient way. Consequently, we show that utilizing the D2D links in cellular networks increases the throughput of a multicast session by means of simulation. We also discuss some practical issues facing the integration of LiC into the current cellular networks. In particular, we propose efficient delay control mechanism to reduce the average and maximum delay experienced by LiC users, which is further confirmed by the simulation results.

  16. RMAC: A Reliable MAC Protocol Supporting Multicast for Wireless Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Wei-Sheng Si; Cheng-Zhi Li

    2005-01-01

    This paper presents a new reliable MAC protocol called "RMAC" supporting reliable multicast for wireless ad hoc networks. By utilizing the busy tones to realize the multicast reliability, RMAC has three novelties: (1) it uses a variablelength control frame to stipulate an order for the receivers to respond, thus solving the feedback collision problem; (2) it extends the usage of busy tone for preventing data frame collisions into the multicast scenario; and (3) it introduces a new usage of busy tone for acknowledging data frames positively. In addition, RMAC is generalized into a comprehensive MAC protocol that provides both reliable and unreliable services for all the three modes of communications: unicast, multicast,and broadcast, making it capable of supporting various upper-layer protocols. The evaluation shows that RMAC achieves high reliability with very limited overhead. RMAC is also compared with other reliable MAC protocols, showing that RMAC not only provides higher reliability but also involves lower cost.

  17. Corrections to "Connectivity-Based Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs"

    Directory of Open Access Journals (Sweden)

    Choi Woo-Yong

    2010-01-01

    Full Text Available We have found the errors in the throughput formulae presented in our paper "Connectivity-based reliable multicast MAC protocol for IEEE 802.11 wireless LANs". We provide the corrected formulae and numerical results.

  18. Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs with Extended Service Range

    Science.gov (United States)

    Choi, Woo-Yong

    2011-11-01

    In this paper, we propose the efficient reliable multicast MAC protocol by which the AP (Access Point) can transmit reliably its multicast data frames to the recipients in the AP's one-hop or two-hop transmission range. The AP uses the STAs (Stations) that are directly associated with itself as the relays for the data delivery to the remote recipients that cannot be reached directly from itself. Based on the connectivity information among the recipients, the reliable multicast MAC protocol optimizes the number of the RAK (Request for ACK) frame transmissions in a reasonable computational time. Numerical examples show that our proposed MAC protocol significantly enhances the MAC performance compared with the BMMM (Batch Mode Multicast MAC) protocol that is extended to support the recipients that are in the AP's one-hop or two-hop transmission range in IEEE 802.11 wireless LANs.

  19. Reliability Evaluation Method for IP Multicast Communication under QoS Constraints

    Institute of Scientific and Technical Information of China (English)

    Dai Fusheng; Bao Xuecai; Han Weizhan

    2011-01-01

    In order to estimate the reliability performance of multicast communication under multiple constraint conditions,the weight of service rate and the reliability index are defined,accompanying the calculation method.Firstly,according to the Quality of Service requirements,the appropriate routings between the central node and target nodes that meet the requirements are calculated using the iterative method in the weighted internet.Then,the disjoint set of network state and the coefficients of weighted service rate are calculated by decomposition and merge methods.Lastly,the formula for calculating the service rate is obtained based on the disjoint set of network state and the calculation of the reliability index will be completed.The simulation result shows that the reliability of multicast communication can be appropriately reflected by the weight of service rate and the calculation method,which can provide the theoretical basis for the reliability evaluation of multicast communication.

  20. The specification-based validation of reliable multicast protocol: Problem Report. M.S. Thesis

    Science.gov (United States)

    Wu, Yunqing

    1995-01-01

    Reliable Multicast Protocol (RMP) is a communication protocol that provides an atomic, totally ordered, reliable multicast service on top of unreliable IP multicasting. In this report, we develop formal models for RMP using existing automated verification systems, and perform validation on the formal RMP specifications. The validation analysis help identifies some minor specification and design problems. We also use the formal models of RMP to generate a test suite for conformance testing of the implementation. Throughout the process of RMP development, we follow an iterative, interactive approach that emphasizes concurrent and parallel progress of implementation and verification processes. Through this approach, we incorporate formal techniques into our development process, promote a common understanding for the protocol, increase the reliability of our software, and maintain high fidelity between the specifications of RMP and its implementation.

  1. 主动结点启动的可靠多播通信%Active-Node-Initiated Reliable Multicast

    Institute of Scientific and Technical Information of China (English)

    蔡洪斌; 周明天; 杨国纬

    2000-01-01

    Sender-initiated and receiver-initiated reliable multicast protocols can suffer performance degradation as increasing the number of receivers. New technology and new service of active network would resolve the problem of the scalable and reliable multicast. The paper presents an Active-Node-Initiated Reliable Multicast (ANIRM)protocol. The protocol, which guarantees the data packet to transport correctly form active node to active node,shifts the burden of providing reliable data transfer to active nodes and receivers. Theoretical analysis shows that ANIRM proposed here is,comparing with the traditional network protocol,better for bandwidth and data recovery delay.

  2. Energy based reliable multicast routing protocol for packet forwarding in MANET

    Directory of Open Access Journals (Sweden)

    S. Gopinath

    2015-06-01

    Full Text Available Mobile Ad hoc Network consists of mobile nodes without any assisting infrastructure. Mobility of nodes causes network partition. This leads to heavy overhead and less packet forwarding ratio. In this research work, Residual Energy based Reliable Multicast Routing Protocol (RERMR is proposed to attain more network lifetime and increased packet delivery and forwarding rate. A multicast backbone is constructed to achieve more stability based on node familiarity and trustable loop. Reliable path criterion is estimated to choose best reliable path among all available paths. Data packets will be forwarded once the reliable path is chosen. We have also demonstrated that residual energy of paths aids to provide maximum network lifetime. Based on the simulation results, the proposed work achieves better performance than previous protocols in terms of packet reliability rate, network stability rate, end to end delay, end to end transmission and communication overhead.

  3. Specification and Design of a Fault Recovery Model for the Reliable Multicast Protocol

    Science.gov (United States)

    Montgomery, Todd; Callahan, John R.; Whetten, Brian

    1996-01-01

    The Reliable Multicast Protocol (RMP) provides a unique, group-based model for distributed programs that need to handle reconfiguration events at the application layer. This model, called membership views, provides an abstraction in which events such as site failures, network partitions, and normal join-leave events are viewed as group reformations. RMP provides access to this model through an application programming interface (API) that notifies an application when a group is reformed as the result of a some event. RMP provides applications with reliable delivery of messages using an underlying IP Multicast media to other group members in a distributed environment even in the case of reformations. A distributed application can use various Quality of Service (QoS) levels provided by RMP to tolerate group reformations. This paper explores the implementation details of the mechanisms in RMP that provide distributed applications with membership view information and fault recovery capabilities.

  4. SM_TCP: a new reliable multicast transport protocol for satellite IP networks

    Science.gov (United States)

    Liu, Gongliang; Gu, Xuemai; Li, Shizhong

    2005-11-01

    A new reliable multicast transport protocol SM_TCP is proposed for satellite IP networks in this paper. In SM_TCP, the XOR scheme with the aid of on-board buffering and processing is used for error recovery and an optimal retransmission algorithm is designed, which can reduce the recovery time by half of the RTT and minimize the number of retransmissions. In order to avoid the unnecessary decrease of congestion window in the high BER satellite channels, the occupied buffer sizes at bottlenecks are measured in adjusting the congestion window, instead of depending on the packet loss information. The average session rate of TCP sessions and of multicast sessions passing through the satellite are also measured and compared in adjusting the congestion window, which contributes to bandwidth fairness. Analysis and simulation results show fairness with TCP flows and scalability.

  5. Wurf.it: A Network Coding Reliable Multicast Content Streaming Solution - ns-3 Simulations and Implementation

    DEFF Research Database (Denmark)

    Hernandez, Nestor; Pihl, Jeppe; Heide, Janus

    One of the proven benets of Network Coding (NC) is to achieve the data capacity for multicast networks. However, even though there has been a signicant amount of research in this area, potentials demonstrators of these capabilities have not been widely shown or deployed. Thus, in this work we...... present a set of pre-computed ns-3 simulations to model the behaviour of Wurf.it, a Random Linear Network Coding (RLNC)-based reliable multicast solution for content distribution with cross-platform support. Wurf.it is based on Kodo, a C++11 network coding library that provides the primitive encoding...... demonstrator consists of stored simulations with ns-3 in a laptop and a Wurf.it implementation within a WiFi network. For the implementation, a video content from a mobile camera is distributed with low delay using SCORE to a set of heterogenous receivers (e.g. dierent platforms). Use cases of Wurf.it are mild...

  6. RMD: Reliable Multicast Data Dissemination within Groups of Collaborating Objects

    NARCIS (Netherlands)

    Marin-Perianu, M.; Havinga, P.J.M.

    2006-01-01

    Factory and industrial automation systems gradually start to incorporate wireless networks of smart objects and sensor nodes. In this context, one fundamental problem is the reliability of data dissemination, particularly in the case of total or partial network reconfiguration. We propose RMD, a rel

  7. RMD: Reliable Multicast Data Dissemination within Groups of Collaborating Objects

    NARCIS (Netherlands)

    Marin Perianu, Mihai; Havinga, Paul J.M.

    Factory and industrial automation systems gradually start to incorporate wireless networks of smart objects and sensor nodes. In this context, one fundamental problem is the reliability of data dissemination, particularly in the case of total or partial network reconfiguration. We propose RMD, a

  8. The Impact of Packet Loss Behavior in 802.11g on the Cooperation Gain in Reliable Multicast

    DEFF Research Database (Denmark)

    Heide, Janus; Vingelmann, Peter; Pedersen, Morten Videbæk

    2012-01-01

    In group-oriented applications for wireless networks, reliable multicast strategies are important in order to efficiently distribute data, e.g. in Wireless Mesh Networks (WMNs) and Mobile Ad-hoc NETworks (MANETs). To ensure that developed protocols and systems will operate as expected when deployed...

  9. Wurf.it: A Network Coding Reliable Multicast Content Streaming Solution

    DEFF Research Database (Denmark)

    Hernandez, Nestor; Pihl, Jeppe; Heide, Janus

    present a set of pre-computed ns-3 simulations to model the behaviour of Wurf.it, a Random Linear Network Coding (RLNC)-based reliable multicast solution for content distribution with cross-platform support. Wurf.it is based on Kodo, a C++11 network coding library that provides the primitive encoding...... demonstrator consists of stored simulations with ns-3 in a laptop and a Wurf.it implementation within a WiFi network. For the implementation, a video content from a mobile camera is distributed with low delay using SCORE to a set of heterogenous receivers (e.g. dierent platforms). Use cases of Wurf.it are mild...

  10. The Review on Reliable Multicast%可靠组播研究综述

    Institute of Scientific and Technical Information of China (English)

    吴文峻; 聂树宣

    2001-01-01

    @@ 一、引言 IP网络上各种新应用的开展,如:视频会议、远程教学、网络交互式游戏、远程虚拟现实等等,要求互连网络提供可靠的选播服务(Reliable Multicast,RM).IP层的Multicast通信只提供尽力型服务,不保证选播数据报文的可靠传输,研究高效和可靠的RM机制,完成类似单播服务中TCP的可靠传输功能,成为最近五年来,IP选播协议研究中的重要方向.

  11. An approach to verification and validation of a reliable multicasting protocol: Extended Abstract

    Science.gov (United States)

    Callahan, John R.; Montgomery, Todd L.

    1995-01-01

    This paper describes the process of implementing a complex communications protocol that provides reliable delivery of data in multicast-capable, packet-switching telecommunication networks. The protocol, called the Reliable Multicasting Protocol (RMP), was developed incrementally using a combination of formal and informal techniques in an attempt to ensure the correctness of its implementation. Our development process involved three concurrent activities: (1) the initial construction and incremental enhancement of a formal state model of the protocol machine; (2) the initial coding and incremental enhancement of the implementation; and (3) model-based testing of iterative implementations of the protocol. These activities were carried out by two separate teams: a design team and a V&V team. The design team built the first version of RMP with limited functionality to handle only nominal requirements of data delivery. This initial version did not handle off-nominal cases such as network partitions or site failures. Meanwhile, the V&V team concurrently developed a formal model of the requirements using a variant of SCR-based state tables. Based on these requirements tables, the V&V team developed test cases to exercise the implementation. In a series of iterative steps, the design team added new functionality to the implementation while the V&V team kept the state model in fidelity with the implementation. This was done by generating test cases based on suspected errant or off-nominal behaviors predicted by the current model. If the execution of a test in the model and implementation agreed, then the test either found a potential problem or verified a required behavior. However, if the execution of a test was different in the model and implementation, then the differences helped identify inconsistencies between the model and implementation. In either case, the dialogue between both teams drove the co-evolution of the model and implementation. We have found that this

  12. Unidata LDM-7: a Hybrid Multicast/unicast System for Highly Efficient and Reliable Real-Time Data Distribution

    Science.gov (United States)

    Emmerson, S. R.; Veeraraghavan, M.; Chen, S.; Ji, X.

    2015-12-01

    Results of a pilot deployment of a major new version of the Unidata Local Data Manager (LDM-7) are presented. The Unidata LDM was developed by the University Corporation for Atmospheric Research (UCAR) and comprises a suite of software for the distribution and local processing of data in near real-time. It is widely used in the geoscience community to distribute observational data and model output, most notably as the foundation of the Unidata Internet Data Distribution (IDD) system run by UCAR, but also in private networks operated by NOAA, NASA, USGS, etc. The current version, LDM-6, uses at least one unicast TCP connection per receiving host. With over 900 connections, the bit-rate of total outgoing IDD traffic from UCAR averages approximately 3.0 GHz, with peak data rates exceeding 6.6 GHz. Expected increases in data volume suggest that a more efficient distribution mechanism will be required in the near future. LDM-7 greatly reduces the outgoing bandwidth requirement by incorporating a recently-developed "semi-reliable" IP multicast protocol while retaining the unicast TCP mechanism for reliability. During the summer of 2015, UCAR and the University of Virginia conducted a pilot deployment of the Unidata LDM-7 among U.S. university participants with access to the Internet2 network. Results of this pilot program, along with comparisons to the existing Unidata LDM-6 system, are presented.

  13. Reliable multicast protocol based on reputation mechanism in wireless multi-hop networks%无线多跳网络中基于声誉机制的可靠组播协议

    Institute of Scientific and Technical Information of China (English)

    许力; 蒋佳铭

    2011-01-01

    To improve the reliability of the multicast tree and the efficiency of multicast, a multicast protocol based on reputation mechanism was proposed. The protocol took into account reputation value of the nodes in constructing the multicast tree, thus excluding the selfish nodes from it, making the multicast path comparably reliable. Simulation results show that proposed protocol can significantly improving the efficiency of multicast at a lower cost.%为了提高无线多跳网络中组播树的可靠性和提高组播效率,提出了一种基于声誉机制的组播协议.该协议在构建组播树时考虑了节点的声誉值,从而将自私性节点排除在组播树之外,使得构建的组播路径比较可靠.仿真实验表明该协议可以用较低的代价有效地提高组播效率.

  14. Analysis and Taxonomy of Congestion Control Mechanisms for Internet Reliable Multicast%Internet可靠多点投递拥塞控制机制—分析和分类

    Institute of Scientific and Technical Information of China (English)

    翟明玉; 赵齐; 吴国新; 顾冠群

    2000-01-01

    The research of congestion control for Internet reliable multicast is one of the most active fields in reliable multicast protocol research.Many reliable multicast congestion control mechanisms have been put forward.In this paper we present principal problems of congestion control for Intemet reliable multicast,analyze solutions and difficulties of solving these problems,and then give a classification of some reliable multicast congestion control mechanisms.Lastly the future work is proposed.%Internet可靠多点投递拥塞控制研究是当前可靠多点投递协议研究的活跃领域.许多多点投递拥塞控制机制已经提出来了.本文首先提出Intemet可靠多点投递拥塞控制的基本问题,然后对解决这些问题的方案和遇到的困难进行分析,并对目前已经提出的Intemet可靠多点投递拥塞控制机制进行分类.最后指出将来的工作方向.

  15. Multicast Routing Protocols in Adhoc Mobile networks

    Directory of Open Access Journals (Sweden)

    S.Nagaprasad,

    2010-11-01

    Full Text Available The majority of applications are in areas where rapid deployment and dynamic reconfiguration are necessary and a wire line network is not available. These include military battlefields, emergency search and rescue sites, classrooms, and conventions where participants share information dynamically using their mobile devices. Well established routing protocols do exist to offer efficient multicasting service in conventional wired networks. These protocols, having been designed for fixed networks, may fails to keep up with node movements and frequent topology changes in a MANET. Therefore, adapting existing wired multicast protocols as such to a MANET, which completely lacks infrastructure, appear less promising. Providing efficient multicasting over MANET faces many challenges, includes scalability,quality of service, reliable service, security, Address configuration, Applications for multicast over MANET. The existing multicast routing protocol do not addresses these issues effectively over Mobile Adhoc Networks (MANET.

  16. Design and Implementation of a Large-Scale Active Reliable Multicast Protocol%一个基于主动网络的大规模可靠组播协议的设计和实现

    Institute of Scientific and Technical Information of China (English)

    陈晓林; 李冀; 魏明亮; 陆桑璐; 陈贵海; 谢立

    2001-01-01

    本文提出一个基于主动网络的大规模可靠组播协议LARMP(Large-scale Active Reliable Multicast Protocol),它较全面地解决了NACK/ACK (Negotiate Acknowledge / Acknowledge Implosion)风暴、选择重发、分布恢复负担、拥塞控制、健壮性这五个Internet上的可靠组播面临

  17. 基于CATV网的可靠多播机制研究%Research on Mechanism of Reliable Multicasting Based on CATV Network

    Institute of Scientific and Technical Information of China (English)

    朱梅; 李章维

    2011-01-01

    针对CATV网的带宽优势,提出了一种面向CATV网的IP多播流分发服务机制,客户端通过DVB卡分层接收流武文件,并利用IP网作为回传链路.该方案解决了单向广播网无法回传丢包及网络服务情况的问题,对于网络的突发性长时间丢包具有一定的稳健性.仿真结果显示该方案可靠性强,扩展性好,特别适合具有较多接收者的视频流分发.%According to the advantages of the broad bandwidth of CATV network, an IP multicast streaming distribution mechanism based on CATV network is proposed. Clients receive the streaming file with layer by DVB network interface, and intemet is used as the tatum channel to cope with the Probability of Packet Loss (PPL) and QoS in unidirectional broadcasting networks. The robustness is appeared when the packet loss of network bursts for a long time. The simulating results show that the scheme is reliable and expandable, and is particularly suitable for the video stream distribution with several receivers.

  18. An Application-Level Semantic Reliable Multicast Architecture for the Internet%应用层语义可靠的自适应多播

    Institute of Scientific and Technical Information of China (English)

    谭焜; 史元春; 廖春元; 徐光祐

    2002-01-01

    Internet上的可靠多播具有很大的应用前景,但是同时也面临着挑战,主要是因为Internet的异构性以及IP Multicast仍不能广域内得以实现.提出了一种应用层语义可靠的自适应多播体系结构(application semantics reliable multicast,简称ASRM).ASRM不以IP Multicast为基础,而是采用一种混合IP单播和多播的方法来实现多点数据通信.ASRM采用一种简单、自然,且具有更好的伸缩性的方法来命名多播会话,并可以在转发过程中,根据变换模型、变换规则和用户意愿进行自适应的数据传输,从而解决异构性问题.ASRM适用于广域范围内的小规模可靠多播应用.

  19. A Primer of Multicast Routing

    CERN Document Server

    Rosenberg, Eric

    2012-01-01

    Whereas unicast routing determines a path from one source node to one destination node, multicast routing determines a path from one source to many destinations, or from many sources to many destinations. We survey multicast routing methods for when the set of destinations is static, and for when it is dynamic. While most of the methods we review are tree based, some non-tree methods are also discussed. We survey results on the shape of multicast trees, delay constrained multicast routing, aggregation of multicast traffic, inter-domain multicast, and multicast virtual private networks. We focu

  20. A SURVEY ON MULTICAST ROUTING PROTOCOLS FOR PERFORMANCE EVALUATION IN WIRELESS SENSOR NETWORK

    Directory of Open Access Journals (Sweden)

    A. Suruliandi

    2015-03-01

    Full Text Available Multicast is a process used to transfer same message to multiple receivers at the same time. This paper presents the simulation and analysis of the performance of six different multicast routing protocols for Wireless Sensor Network (WSN. They are On Demand Multicast Routing Protocol (ODMRP, Protocol for Unified Multicasting through Announcement (PUMA, Multicast Adhoc On demand Distance Vector Protocol (MAODV, Overlay Boruvka-based Adhoc Multicast Protocol (OBAMP, Application Layer Multicast Algorithm (ALMA and enhanced version of ALMA (ALMA-H for WSN. Among them, ODMRP, MAODV and PUMA are reactive protocols while OBAMP, ALMA and ALMA-H are proactive protocols. This paper compares the performance of these protocols with common parameters such as Throughput, Reliability, End-to-End delay and Packet Delivery Ratio (PDR with increasing the numbers of nodes and increasing the speed of the nodes. The main objective of this work is to select the efficient multicast routing protocol for WSN among six multicast routing protocol based on relative strength and weakness of each protocol. The summary of above six multicast routing protocols is presented with a table of different performance characteristics. Experimental result shows that ODMRP attains higher throughput, reliability and higher packet delivery ratio than other multicast routing protocol, while incurring far less end-to-end delay.

  1. Security Challenges in Multicast Communication for Mobile Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    S. Gunasekaran

    2010-01-01

    Full Text Available Problem statement: Multicasting communication network accepted a single message from an application and delivered copies of the message to multiple recipients at different locations. Recently, there has been an explosion of research literature on multicast communication environment. The objective of this study were to contribute the complexity of supporting current multicast applications, (i the lack of reliable multicast transport mechanisms at the network level and (ii the lack of network support for large scale multicast communication. The scaling problem of secure multicast key distribution compounded for the case where sender-specific keys need to be distributed to a group and required for sender-specific authentication of data traffic and minimize control overhead (iii compare RC4, AES-128,RS(2 and RS(3 computation time of both algorithms. Approach: Algorithms were collected and performed computation time. In general the multicast key distribution scheme implemented for distributing 128 bit session keys. Thus the Maximum Distance Separable Codes (MDS Codes needed for their encoding and decoding process. In rekeying scheme errors were occurred during over period of time or at a particular point of time and to eliminate all these errors in the level of encryption and decryption mechanism. The MDS codes played an important role in providing security services for multicast, such as traffic, integrity, authentication and confidentiality, is particularly problematic since it requires securely distributing a group (session key to each of a group’s receivers. Results: First we showed that internet multicasting algorithms based on reverse path forwarding were inherently unreliable and present a source-tree-based reliable multicasting scheme also. The new scheme proposed and used as an inter-gateway protocol and worked on top of the previously developed distance vector and link state internet routing schemes. Next, to support large scale

  2. Topology-aware Overlay Multicast over IP Multicast Networks

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao; SHAO Hua-gang; WANG Wei-nong

    2008-01-01

    Most existing overlay multicast approaches refuse to consider any network layer support no matter whether it is available or not. This design principle greatly increases the complexity of the routing algorithms and makes the overlay topologies incompatible with the underlying network. To address these issues, topology-aware overlay multicast over IP multicast networks (TOMIMN) was proposed as a novel overlay multicast protocol, which exploits the cooperation between end-hosts and IP multicast routers to construct a topology-aware overlay tree. Through a little modification to protocol independent multicast sparse mode (PIM-SM),a multicast router is able to receive registration from nearby group members and redirect passing-by join re-quests to them. Due to the multicast router's support, TOMIMN organizes its group members into an overlay multicast tree efficiently, which matches the physical network topology well.

  3. Merging Network Coding with Feedback Management in Multicast Streaming

    DEFF Research Database (Denmark)

    Moreira, André; Almeida, Luis; Roetter, Daniel Enrique Lucani

    2015-01-01

    Reliable multicast over wireless poses interesting challenges arising from the unreliable nature of the wireless medium. Recovering lost packets is particularly challenging in multicast scenarios since different receivers lose different packets. For this reason, simply retransmitting packets does......-case delay as required for QoS sensitive applications. We show preliminary simulation results that confirm the bounded decoding delay of our approach in a streaming application....

  4. VMCast: A VM-Assisted Stability Enhancing Solution for Tree-Based Overlay Multicast.

    Science.gov (United States)

    Gu, Weidong; Zhang, Xinchang; Gong, Bin; Zhang, Wei; Wang, Lu

    2015-01-01

    Tree-based overlay multicast is an effective group communication method for media streaming applications. However, a group member's departure causes all of its descendants to be disconnected from the multicast tree for some time, which results in poor performance. The above problem is difficult to be addressed because overlay multicast tree is intrinsically instable. In this paper, we proposed a novel stability enhancing solution, VMCast, for tree-based overlay multicast. This solution uses two types of on-demand cloud virtual machines (VMs), i.e., multicast VMs (MVMs) and compensation VMs (CVMs). MVMs are used to disseminate the multicast data, whereas CVMs are used to offer streaming compensation. The used VMs in the same cloud datacenter constitute a VM cluster. Each VM cluster is responsible for a service domain (VMSD), and each group member belongs to a specific VMSD. The data source delivers the multicast data to MVMs through a reliable path, and MVMs further disseminate the data to group members along domain overlay multicast trees. The above approach structurally improves the stability of the overlay multicast tree. We further utilized CVM-based streaming compensation to enhance the stability of the data distribution in the VMSDs. VMCast can be used as an extension to existing tree-based overlay multicast solutions, to provide better services for media streaming applications. We applied VMCast to two application instances (i.e., HMTP and HCcast). The results show that it can obviously enhance the stability of the data distribution.

  5. VMCast: A VM-Assisted Stability Enhancing Solution for Tree-Based Overlay Multicast.

    Directory of Open Access Journals (Sweden)

    Weidong Gu

    Full Text Available Tree-based overlay multicast is an effective group communication method for media streaming applications. However, a group member's departure causes all of its descendants to be disconnected from the multicast tree for some time, which results in poor performance. The above problem is difficult to be addressed because overlay multicast tree is intrinsically instable. In this paper, we proposed a novel stability enhancing solution, VMCast, for tree-based overlay multicast. This solution uses two types of on-demand cloud virtual machines (VMs, i.e., multicast VMs (MVMs and compensation VMs (CVMs. MVMs are used to disseminate the multicast data, whereas CVMs are used to offer streaming compensation. The used VMs in the same cloud datacenter constitute a VM cluster. Each VM cluster is responsible for a service domain (VMSD, and each group member belongs to a specific VMSD. The data source delivers the multicast data to MVMs through a reliable path, and MVMs further disseminate the data to group members along domain overlay multicast trees. The above approach structurally improves the stability of the overlay multicast tree. We further utilized CVM-based streaming compensation to enhance the stability of the data distribution in the VMSDs. VMCast can be used as an extension to existing tree-based overlay multicast solutions, to provide better services for media streaming applications. We applied VMCast to two application instances (i.e., HMTP and HCcast. The results show that it can obviously enhance the stability of the data distribution.

  6. An Approach of Extending Scalability of Reliable Multicast Protocols%可靠组播通信中可扩展性问题的研究

    Institute of Scientific and Technical Information of China (English)

    付培荣; 李冀; 魏明亮; 乐正宜; 陈贵海; 谢立

    2001-01-01

    @@ 1 引言 IP Multicast技术,特别是 MBONE(Multicast Backbone)的发展,使得Internet上需要多目传输支持的应用,如视频会议,成为可能.可扩展性是组播协议研究的一个重要方面,它决定了一个协议在组规模基础上的可扩展能力与协议的适应性.

  7. Multicast and IP Multicast Support in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jorge Sá Silva

    2008-03-01

    Full Text Available Multicast potentially optimises bandwidth consumption and node resources, when several users simultaneously participate in a communication session. Nevertheless, contrary to the expectations, IP multicast has not experienced widespread deployment, with the exception of IPTV. On the other hand, emerging Wireless Sensor Network (WSN applications could greatly benefit from multicast and constitute another field where multicast can be an effective and efficient technique. The questions are: do multicast advantages hold in WSN scenarios? Can we use IP Multicast functionality in WSNs? This paper discusses and evaluates the use of multicast in WSNs. Specifically, we evaluate the use of Source-Specific Multicast, as it is one of the most promising paradigms for IP networking, considering both IPv4 and IPv6 in WSNs. A sensor platform with IP and multicast support that is being developed in our lab is presented. Concurrently, simulation studies were performed in order to assess the usefulness of multicast in WSNs. The results clearly point to the benefits of the use of this technique in processing and energy-restricted environments such as this one.

  8. SUPPORTING MPLS VPN MULTICAST

    Institute of Scientific and Technical Information of China (English)

    Wang Yufeng; Wang Wendong; Cheng Shiduan

    2004-01-01

    MPLS(Multi-Protocol Label Switching) VPN(Virtual Private Network) traffic has been deployed widely, but currently only supports unicast. This paper briefly introduces several available MPLS VPN multicast approaches, and then analyzes their disadvantages. A novel mechanism that uses two-layer label stack to support MPLS VPN explicit multicast is proposed and the process is discussed in detail. The scalability and performance of the proposed mechanism are studied analytically. The result shows that our solution has great advantage over the currently available scheme in terms of saving core network bandwidth and improving the scalability.

  9. Multicast Capacity Scaling of Wireless Networks with Multicast Outage

    CERN Document Server

    Liu, Chun-Hung

    2010-01-01

    Multicast transmission has several distinctive traits as opposed to more commonly studied unicast networks. Specially, these include (i) identical packets must be delivered successfully to several nodes, (ii) outage could simultaneously happen at different receivers, and (iii) the multicast rate is dominated by the receiver with the weakest link in order to minimize outage and retransmission. To capture these key traits, we utilize a Poisson cluster process consisting of a distinct Poisson point process (PPP) for the transmitters and receivers, and then define the multicast transmission capacity (MTC) as the maximum achievable multicast rate times the number of multicast clusters per unit volume, accounting for outages and retransmissions. Our main result shows that if $\\tau$ transmission attempts are allowed in a multicast cluster, the MTC is $\\Theta\\left(\\rho k^{x}\\log(k)\\right)$ where $\\rho$ and $x$ are functions of $\\tau$ depending on the network size and density, and $k$ is the average number of the inte...

  10. multicast utilizando Simulated Annealing

    Directory of Open Access Journals (Sweden)

    Yezid Donoso

    2005-01-01

    Full Text Available En este artículo se presenta un método de optimización multiobjetivo para la solución del problema de balanceo de carga en redes de transmisión multicast, apoyándose en la aplicación de la meta-heurística de Simulated Annealing (Recocido Simulado. El método minimiza cuatro parámetros básicos para garantizar la calidad de servicio en transmisiones multicast: retardo origen destino, máxima utilización de enlaces, ancho de banda consumido y número de saltos. Los resultados devueltos por la heurística serán comparados con los resultados arrojados por el modelo matemático propuesto en investigaciones anteriores.

  11. Netrawalm: Network Based Resource Aware Application Layer Multicast for Multiparty Video Conference

    CERN Document Server

    Ruso, T

    2011-01-01

    IP Multicast is one of the most absolute method for large bandwidth Internet applications such as video conference, IPTV, E-Learning and Telemedicine etc., But due to security and management reason IP Multicast is not enabled in Internet backbone routers. To achieve these challenges, lot of Application Layer Multicast (ALM) has been proposed. All the existing protocols such as NICE, ZIGZAG and OMNI are trying to reduce average delay by forming a Multicast tree. But still that problem has not been addressed fully. We are proposing a new protocol called NetRawALM, which will address the average delay, Reliability between nodes, Scalability of conference, Heterogeneity and resilient data distribution for real time multimedia applications by constructing the Network based Resource aware Multicast tree algorithm. This is very dynamic and decentralised. The proposed architecture is a LAN aware; it is used to reduce Internet Traffic.

  12. Multimedia multicast on the Internet

    CERN Document Server

    Benslimane, Abderrahim

    2010-01-01

    This book examines multicast technology and will be a key text for undergraduate engineering students and master students in networks and telecoms. However, it will be equally useful for a wide range of professionals in this research field. Multicast routing was introduced with the advent of multiparty applications (for example, videoconferencing on the Internet) and collaborative work (for example, distributed simulations). It is related to the concept of group communication, a technique introduced to reduce communication costs. The various problems of multicast routing on the Internet are

  13. An Improved Multicast Routing Algorithm

    Institute of Scientific and Technical Information of China (English)

    蒋廷耀; 李庆华

    2004-01-01

    Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper,we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks.

  14. Protection switching for carrier ethernet multicast

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Berger, Michael Stübert

    2010-01-01

    This paper addresses network survivability for IPTV multicast transport in Carrier Ethernet networks. The impact of link failures is investigated and suggestions for intelligent multicast resilience schemes are proposed. In particular, functions of the multicast tree are integrated with the Carrier...

  15. A Study of Broadband Intelligent Network Implementing Video Conference and Multicast Routing Algorithm

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dissertation studies the architecture of broadbandintelligent network (BIN) and implementation of video conference based on ATM network and of multicast routing problem on video conference using BIN under the aid of the important task-Study of IN and B-ISDN Integration (69896244)-sponsored by National Natural Science Fund. A lot of points of view and solutions are present. The main contributions in the dissertation are as follows: (1) Design the new architecture of BIN and improve the architecture of BIN proposed by ITU-T. It is easy to set up the connections of video conference using the new architecture of BIN.(2) Present the detailed scheme that BIN controls and implements video conference without specialized resource function, study the scheme of all the media on video conference transmitted and switched under the control of BIN, and discuss how to implement point-to-multipoint communications using BIN. (3) First present the scheme of implementing multicast routing algorithms on video conference using BIN.(4) Explicitly introduce a series of concepts including neighboring node, neighboring node set, neighboring edge, then propose an Adjustable Dynamic Multicast (ADM) routing algorithm which is suitable for video conference, analyze its performances, and prove the algorithm is appropriate and feasible. (5) Develop a degree-constrained dynamic multicast (DADM) routing algorithm which can find less cost multicast routing tree. The results of simulation and experiments confirm that DADM algorithm can find the less cost multicast tree. Finally, analyze the relation between the size of degree-constrained and value of multicast tree cost. (6) Present a delay-constrained dynamic multicast routing algorithm suitable for video conference characteristic, and advise a series of schemes reducing the delay of transmitting all the media on videoconference.(7) First propose implementing the reliable multicast routing transport protocol using BIN, thereby ACK implosion

  16. Using multicast in the global communications infrastructure for group communication

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Deborah A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    1999-07-30

    International Monitoring System (IMS) stations and the International Data Centre (IDC) of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization generate data and products that must be transmitted to one or more receivers. The application protocols used to transmit the IMS data and IDC products will be CD-x and IMS-x and the World Wide Web (WWW). These protocols use existing Internet applications and Internet protocols to send their data. The primary Internet applications in use are electronic mail (e-mail) and the file transfer protocol (ftp). The primary Internet communication protocol in use is the Transmission Control Protocol (TCP), which provides reliable delivery to the receiver. These Internet applications and protocol provide unicast (point-to-point) communication. A message sent using unicast has a single recipient; any message intended for more than one recipient must be sent to each recipient individually. In the current design, the IDC and the National Data Centres (NDC's) provide data forwarding to the appropriate receivers. The overhead associated with using unicast to transmit messages to multiple receivers either directly or through a forwarder increases linearly with the number of receivers. In addition, using a forwarding site introduces possible delays and possible points of failure in the path to the receivers. Reliable multicast provides communication services similar to TCP but for a group of receivers. The reliable multicast protocol provides group membership services and message delivery ordering. If an IMS station were to send its data using reliable multicast instead of unicast, only sites that are members of the multicast group would receive the data at approximately the same time. This might provide an efficient means of disseminating station data or IDC data products to all receivers and eliminate or greatly reduce the need for data forwarding. Several commercial and research reliable multicast

  17. NETRAWALM: NETWORK BASED RESOURCE AWARE APPLICATION LAYER MULTICAST FOR MULTIPARTY VIDEO CONFERENCE

    Directory of Open Access Journals (Sweden)

    T. Ruso

    2011-10-01

    Full Text Available IP Multicast is one of the most absolute method for large bandwidth Internet applications such as videoconference, IPTV, E-Learning and Telemedicine etc., But due to security and management reason IPMulticast is not enabled in Internet backbone routers. To achieve these challenges, lot of ApplicationLayer Multicast (ALM has been proposed. All the existing protocols such as NICE, ZIGZAG and OMNIare trying to reduce average delay by forming a Multicast tree. But still that problem has not beenaddressed fully. We are proposing a new protocol called NetRawALM, which will address the averagedelay, Reliability between nodes, Scalability of conference, Heterogeneity and resilient data distributionfor real time multimedia applications by constructing the Network based Resource aware Multicast treealgorithm. This is very dynamic and decentralised. The proposed architecture is a LAN aware; it is usedto reduce Internet Traffic.

  18. System for Multicast File Transfer

    Directory of Open Access Journals (Sweden)

    Dorin Custura

    2012-03-01

    Full Text Available The distribution of big files over the network from a single source to a large number of recipients is not efficient by using standard client-server or even peer-to peer file transfer protocols.  Thus, the transfer of a hierarchy of big files to multiple destinations can be optimized in terms of bandwidth usage and data storage reads by using multicast networking. In order to achieve that, a simple application layer protocol can be imagined. It uses multicast UDP as transport and it provides a mechanism for data ordering and retransmission. Some security problems are also considered in this protocol, because at this time the Internet standards supporting multicast security are still in the development stage.

  19. Multicast Routing in Satellite Network

    Institute of Scientific and Technical Information of China (English)

    郭惠玲; 宋姝; 李磊; 刘志涛; 郭鹏程

    2004-01-01

    There are some problems in the dual-layer satellite MPLs metworks to be composed of LEO and MEO. In order to solve the problems, this paper presents a plan by means of unicast LSP to implement multicast in the dual-layer satellite MPLs networks. It has advantages of saving space and reducing extra charge.

  20. Application Layer Multicast Technology of Streaming Media

    Directory of Open Access Journals (Sweden)

    Jiansheng Liu

    2011-08-01

    Full Text Available With the rapid development of network technology, Internet business has been transferred from a simple text into a host text, audio, video and other streaming services. Application layer multicast is one of the key technologies to protect the large-scale service quality of streaming media system, which has become an important part of study. Based on the application layer multicast technology, it focused on analyzing the effects of application layer multicast to the  large-scale of media streaming system, and summarized the typical characteristics of the system. It takes efficiency of multicast robustness, scalability, and the continuity as evaluation indexes, and summarized the typical multicast. In the end,the drawbacks and develop directions of application layer multicast were discussed.

  1. Evolutionary biology of CD1.

    Science.gov (United States)

    Dascher, C C

    2007-01-01

    The recognition more than a decade ago that lipids presented by CD1 could function as T cell antigens revealed a startling and previously unappreciated complexity to the adaptive immune system. The initial novelty of lipid antigen presentation by CD1 has since given way to a broader perspective of the immune system's capacity to sense and respond to a diverse array of macromolecules. Some immune recognition systems such as Toll-like receptors can trace their origins back into the deep history of sea urchins and arthropods. Others such as the major histocompatibility complex (MHC) appear relatively recently and interestingly, only in animals that also possess a jaw. The natural history of CD1 is thus part of the wider story of immune system evolution and should be considered in this context. Most evidence indicates that CD1 probably evolved from a classical MHC class I (MHC I) gene at some point during vertebrate evolution. This chapter reviews the evidence for this phylogenetic relationship and attempts to connect CD1 to existing models of MHC evolution. This endeavor is facilitated today by the recent availability of whole genome sequence data from a variety of species. Investigators have used these data to trace the ultimate origin of the MHC to a series of whole genome duplications that occurred roughly 500 million years ago. Sequence data have also revealed homologs of the mammalian MHC I and MHC II gene families in virtually all jawed vertebrates including sharks, bony fishes, reptiles, and birds. In contrast, CD1 genes have thus far been found only in a subset of these animal groups. This pattern of CD1 occurrence in the genomes of living species suggests the emergence of CD 1 in an early terrestrial vertebrate.

  2. A Bypass-Ring Scheme for a Fault Tolerant Multicast

    Directory of Open Access Journals (Sweden)

    V. Dynda

    2003-01-01

    Full Text Available We present a fault tolerant scheme for recovery from single or multiple node failures in multi-directional multicast trees. The scheme is based on cyclic structures providing alternative paths to eliminate faulty nodes and reroute the traffic. Our scheme is independent of message source and direction in the tree, provides a basis for on-the-fly repair and can be used as a platform for various strategies for reconnecting tree partitions. It only requires an underlying infrastructure to provide a reliable routing service. Although it is described in the context of a message multicast, the scheme can be used universally in all systems using tree-based overlay networks for communication among components.

  3. PIM-SM Based Multicast Security%基于PIM-SM协议IP组播安全技术

    Institute of Scientific and Technical Information of China (English)

    黄舒; 董喜明; 郭云峰

    2014-01-01

    With the rapid development of the network technology, more bandwidth is required. Multicast transmission offers efficient network resource consumption. Multicast security is a hot issue. Multicast security problem hinders the development of multicast technology. This paper discusses the principles of multicast protocol PIM-SM and makes a detailed description of a method to prevent vicious multicast source attacking. The method can improve the reliability of multicast system.%伴随着互联网的高速发展, Internet 上涌现了许多需要高带宽支持的应用。组播技术能有效的利用网络带宽资源。组播的安全性一直是一个热点问题,也是阻碍组播发展的一个主要问题。本文针对虚假组播源产生垃圾消息恶性攻击提出了一个基于 PIM-SM 组播协议的预防方案,实验结果表明,该方案能提高组播系统的可靠性。

  4. Internet连续媒体多播技术综述%Survey of Techniques for Internet Continuous Media Multicast

    Institute of Scientific and Technical Information of China (English)

    杨明; 张福炎

    2002-01-01

    Continuous media multicast has been an important component of many networked services such as audio-visual broadcast and video conferencing.The problems of scalability,congestion control,heterogeneity and reliability,which confront Internet continuous media multicast,are presented first,and then overview of the adaptive rate control schemes and techniques to solve these problems are stated.Finally,we discuss some treds and unsolved issues in the field.

  5. Multimedia Conferencing System and Multicasting

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The multimedia conferencing system is an important tool for Computer-supported Cooperative Work (CSCW), and also one of the basic techniques supporting team work in the Concurrent Engineering. In this paper the architecture and function modules of the reported multimedia conferencing system are described. Then in order to reduce the network bandwidth required by the conferencing system, two methods for sending the conferencing data by using multicasting are discussed.

  6. Employing Multicast in P2P Overlay Networks

    Science.gov (United States)

    Kolberg, Mario

    The work on multicast has evolved from bottom IP layer multicast to Application Layer Multicast. While there are issues with the dep-loyment of IP layer multicast, it outperforms Application Layer Multicast. However, the latter has the advantage of an easier dep-loyment. Furthermore, as will be illustrated later in this Chapter, IP layer multicast has the potential to make parallel overlay operations more efficient. Application Layer Multicast is primarily used to send application specific messages/data to a number of nodes.

  7. Providing resilience for carrier ethernet multicast traffic

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang

    2009-01-01

    This paper presents an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we detail how multicast traffic, which is essential for e.g. IPTV can be protected. We present Carrier Ethernet resilience methods for linear and ring networks and show by simulation...... that the availability of a multicast connection can be significantly increased by applying relevant resilience techniques....

  8. A Multicast Routing to Improve Multicast Capacity with Minimal Network Coding Cellsin WDM Networks

    Science.gov (United States)

    Liu, Huanlin; Zhou, Bangtao; Chen, Yong

    2014-12-01

    Multicast routing based on network coding can save large wavelength channels with high network coding operation costs for the all-optical WDM network. An optical multicast routing algorithm based on minimum network coding cells to reach the multicast max-flow is proposed in the paper. The algorithm selects path in the K shortest paths from source to each destination which meets the two criteria. One is to select paths making the least probability of dropping multicast max-flow. The other is to make the path lowest potential path coding cells in the K shortest paths. We investigate that the previously proposed multicast algorithms based on network coding choose the shortest paths or link-disjoint highest shared links to construct network coding sub-graph which may result in the large coding operation cost and decrease the possibility of getting the maximal multicast flow. The simulation results show that the proposed algorithm can effectively reduce the network coding cells and improve the possibility of achieving the multicast max-flow by using our designed two path selection criteria. In addition, the proposed multicast algorithm deteriorates a very limited multicast link costs which is very close to the lowest link costs. So, the proposed algorithm can get the cost-effective multicast routing for the optical networks.

  9. Routing in DiffServ multicast environment

    Science.gov (United States)

    Verma, Shekhar

    2002-07-01

    QOS aware applications have propelled the development of two complementary technologies, Multicasting and Differentiated Services. To provide the required QOS on the Internet, either the bandwidth needs to be increased (Multicasting) or limited bandwidth prioritized among users (DiffServ). Although, the bandwidth on the Internet is continually increasing, the backbone is still insufficient to support QOS without resource allocations. Hence, there is a need to map multicasting in a DiffServ Environment to conserve network bandwidth and to provision this bandwidth in an appropriate fashion. In this regard, two issues have to be addressed. One, the key difference between multicast and DiffServe routing is the structure of the multicast tree. This tree is maintained in multicast aware routers whereas in DiffServe, the core routers maintain no state information regarding the flows. Second, the task of restructuring the multicast tree when members join/leave. Currently, the first issue is addressed by embedding the multicast information within the packet itself as an additional header field. In this paper, we propose a neural network based heuristic approach to address the second problem of routing in a dynamic DiffServe Multicast environment. Many dynamic multicast routing algorithms have been proposed. The greedy algorithm creates a near optimal tree when a node is added but requires many query/reply messages. The PSPT algorithm cannot construct a cost optimal tree. The VTDM algorithm requires the estimated number of nodes that will join and is not flexible. The problem of building an optimal tree to satisfy QOS requirements at minimum cost and taking minimum network resources is NP- complete and none of the above solutions give an optimal solution. We have modeled this combinatorial optimization as a nonlinear programming problem and trained an artificial neural network to solve the problem. The problem is tractable only when the QOS parameters are combined into Diff

  10. Many-to-Many Multicast Routing Schemes under a Fixed Topology

    Directory of Open Access Journals (Sweden)

    Wei Ding

    2013-01-01

    Full Text Available Many-to-many multicast routing can be extensively applied in computer or communication networks supporting various continuous multimedia applications. The paper focuses on the case where all users share a common communication channel while each user is both a sender and a receiver of messages in multicasting as well as an end user. In this case, the multicast tree appears as a terminal Steiner tree (TeST. The problem of finding a TeST with a quality-of-service (QoS optimization is frequently NP-hard. However, we discover that it is a good idea to find a many-to-many multicast tree with QoS optimization under a fixed topology. In this paper, we are concerned with three kinds of QoS optimization objectives of multicast tree, that is, the minimum cost, minimum diameter, and maximum reliability. All of three optimization problems are distributed into two types, the centralized and decentralized version. This paper uses the dynamic programming method to devise an exact algorithm, respectively, for the centralized and decentralized versions of each optimization problem.

  11. A TWO-LAYER RECURRENT NEURAL NETWORK BASED APPROACH FOR OVERLAY MULTICAST

    Institute of Scientific and Technical Information of China (English)

    Liu Shidong; Zhang Shunyi; Zhou Jinquan; Qiu Gong'an

    2008-01-01

    Overlay multicast has become one of the most promising multicast solutions for IP network, and Neutral Network(NN) has been a good candidate for searching optimal solutions to the constrained shortest routing path in virtue of its powerful capacity for parallel computation. Though traditional Hopfield NN can tackle the optimization problem, it is incapable of dealing with large scale networks due to the large number of neurons. In this paper, a neural network for overlay multicast tree computation is presented to reliably implement routing algorithm in real time. The neural network is constructed as a two-layer recurrent architecture, which is comprised of Independent Variable Neurons (IDVN) and Dependent Variable Neurons (DVN), according to the independence of the decision variables associated with the edges in directed graph. Compared with the heuristic routing algorithms, it is characterized as shorter computational time, fewer neurons, and better precision.

  12. CodedStream: live media streaming with overlay coded multicast

    Science.gov (United States)

    Guo, Jiang; Zhu, Ying; Li, Baochun

    2003-12-01

    Multicasting is a natural paradigm for streaming live multimedia to multiple end receivers. Since IP multicast is not widely deployed, many application-layer multicast protocols have been proposed. However, all of these schemes focus on the construction of multicast trees, where a relatively small number of links carry the multicast streaming load, while the capacity of most of the other links in the overlay network remain unused. In this paper, we propose CodedStream, a high-bandwidth live media distribution system based on end-system overlay multicast. In CodedStream, we construct a k-redundant multicast graph (a directed acyclic graph) as the multicast topology, on which network coding is applied to work around bottlenecks. Simulation results have shown that the combination of k-redundant multicast graph and network coding may indeed bring significant benefits with respect to improving the quality of live media at the end receivers.

  13. Single-Source Oriented Application Level Multicast

    Institute of Scientific and Technical Information of China (English)

    PI Ren-jie; SONG Jun-de

    2004-01-01

    Using application level multicast can partly pad the lack of IP multicast deployment. To perform single-source applications in hierarchical topology, we propose an application level multicast approach, Hierarchical Topology Aware Grouping (HTAG), which exploits information about path overlap among members and topological hierarchy to construct overlay tree at different network layers. We present simulations of both our protocol and the TAG over generated hierarchical topologies. The results indicate the effectiveness of our approach in reducing duplicate packets and preserving available bandwidth, with reasonable delays increase.

  14. Application of Multicast-based Video Conference on CERNET Backbone

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Multicast-based video conference is a representative application in advanced network. In multi-point video conference using multicast can get better efficiency facilitated by inner-group broadcast mechanism. In the application, the multicast-based network resources assignment, management and security should be considered together. This paper presents a framework model of multicast-based video conferencing application with three layers. And a practical multicast-based video conferencing is implemented in CERNET(China Education and Research Network) backbone. The practice is valuable for the development of multicast-based video conferencing application in China.

  15. Research on performance of multicasting in optical packet switched networks

    Institute of Scientific and Technical Information of China (English)

    Xin Liu; Yuefeng Ji; Lin Bai; Hongxiang Wang; Yongmei Sun

    2009-01-01

    @@ Different multicasting schemes in optical packet switched networks are discussed, including the parallel mode, serial mode, and hybrid mode multicasting schemes.Simulated modeling technique is applied to compare the network-level performance of the three multicasting schemes.A conclusion can be drawn from the results that since the hybrid-mode multicasting scheme can increase the multicast success ratio and reduce the packet retransmission times compared with the other two schemes, it is the best choice for delivering multicasting sessions in the optical packet switched networks.

  16. Membangun Server Multicast Berbasis Streaming Menggunakan Centos

    Directory of Open Access Journals (Sweden)

    Irwan Susanto

    2009-11-01

    Full Text Available The development of IP-based technology contribute to the development of telecomunication and information technology.  One of  IP-based technology application is streaming multicast, as part of broadcasting. The streaming  process is made by accessing  Telkom-2 broadcast  through AKATEL LAN network, then  server forward it to clients using multicast IP system. Multicast IP is D-class IP, which is able to send data package in realtime. In multicast system, server only send one data package to  some clients with same speed transmition. The Telkom-2 broadcast is already accessed before   sent as data package. Server will access Telkom-2 broadcast using parabola antenna and Hughes modem, then forward it to clients through AKATEL LAN network. Clients must conect to server via AKATEL LAN network and already  instaled VLC player, in order to be able to access the Telkom-2 broadcast

  17. Evaluating multicast resilience in carrier ethernet

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang;

    2010-01-01

    This paper gives an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we show how multicast traffic, which is essential for IPTV can be protected. We detail the ackground for resilience mechanisms and their control and e present Carrier Ethernet...... resilience methods for linear nd ring networks. By simulation we show that the vailability of a multicast connection can be significantly increased by applying protection methods....

  18. Evaluating multicast resilience in carrier ethernet

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang

    2010-01-01

    This paper gives an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we show how multicast traffic, which is essential for IPTV can be protected. We detail the ackground for resilience mechanisms and their control and e present Carrier Ethernet...... resilience methods for linear nd ring networks. By simulation we show that the vailability of a multicast connection can be significantly increased by applying protection methods....

  19. IPTV multicast with peer-assisted lossy error control

    Science.gov (United States)

    Li, Zhi; Zhu, Xiaoqing; Begen, Ali C.; Girod, Bernd

    2010-07-01

    Emerging IPTV technology uses source-specific IP multicast to deliver television programs to end-users. To provide reliable IPTV services over the error-prone DSL access networks, a combination of multicast forward error correction (FEC) and unicast retransmissions is employed to mitigate the impulse noises in DSL links. In existing systems, the retransmission function is provided by the Retransmission Servers sitting at the edge of the core network. In this work, we propose an alternative distributed solution where the burden of packet loss repair is partially shifted to the peer IP set-top boxes. Through Peer-Assisted Repair (PAR) protocol, we demonstrate how the packet repairs can be delivered in a timely, reliable and decentralized manner using the combination of server-peer coordination and redundancy of repairs. We also show that this distributed protocol can be seamlessly integrated with an application-layer source-aware error protection mechanism called forward and retransmitted Systematic Lossy Error Protection (SLEP/SLEPr). Simulations show that this joint PARSLEP/ SLEPr framework not only effectively mitigates the bottleneck experienced by the Retransmission Servers, thus greatly enhancing the scalability of the system, but also efficiently improves the resistance to the impulse noise.

  20. Efficient Cluster Based Multicast Tree for Secure Multicast Communication for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    D.Suganya Devi

    2010-05-01

    Full Text Available Secure multicast communication in mobile adhoc networks is challenging due to its inherent characteristics of infrastructure-less architecture with lack of central authority, limited resources such as bandwidth, time and power. Hence key management is the fundamental challenge in achieving secure communication using multicast key distribution in mobile adhoc networks. In many multicast interactions, due to its frequent node mobility, new member can join and current members can leave at a time due to node failure which causes delay in multicast transmission. This paper proposes a new efficient cluster based multicast tree (CBMT algorithm for secure multicast Communication, in which source node uses Multicast version of Destination Sequenced Distance Vector(MDSDV routing protocol to collects its 1 hop neighbors to form cluster and each node which have child node is elected as the Local controllers of the created clusters. It also tolerates the faults that causes due to failure of nodes. Simulation results shows the demonstration of CBMT using MDSDV have better system performance in terms of end to end delay and fault tolerance rate under varying network conditions.

  1. Multicasting in a WDM-upgraded Resilient Packet Ring

    Science.gov (United States)

    Scheutzow, Michael; Seeling, Patrick; Maier, Martin; Reisslein, Martin

    2007-05-01

    The recently approved IEEE 802.17 Resilient Packet Ring (RPR) network deteriorates under multicast traffic to legacy ring technologies that do not support spatial reuse. We extend our multicast approach with spatial reuse from a currently single-channel RPR to WDM-upgraded multichannel RPR networks, where each node can transmit packets on all wavelengths and receive on one wavelength, and analyze their multicast capacity. Our analysis provides a convenient method for evaluating the multicast and reception capacities of WDM-upgraded RPR networks for a wide range of uniform unicast, multicast, and broadcast traffic scenarios.

  2. Security in Multicasting System with Diversity Combining Techniques

    Directory of Open Access Journals (Sweden)

    Rosni Sayed

    2016-10-01

    Full Text Available This paper is concerned with a Rayleigh fading multicasting SIMO network, where a single source transmits to a group of users in the presence of an eavesdropper. We consider selection combining (SC and maximal ratio combining (MRC diversity techniques at the receivers and eavesdropper. We derive the closed-form analytical expressions for the probability of nonzero secrecy multicast capacity, and ergodic secrecy multicast capacity. This analysis shows, how the channel diversity enhances security in multicast channels. We also present a comparison between SC and MRC diversity techniques to show which technique is better for secure wireless multicasting.

  3. A Kind of New Multicast Routing Algorithm for Application of Internet of Things

    Directory of Open Access Journals (Sweden)

    G. Li

    2013-08-01

    Full Text Available Wireless Sensor Networks (WSN is widely used as an effective medium to integrate physical world and information world of Internet of Things (IOT. While keeping energy consumption at a minimal level, WSN requires reliable communication. Multicasting is a general operation performed by the Base Station, where data is to be transmitted to a set of destination nodes. Generally, the packets are routed in a multi-hop approach, where some intermediate nodes are also used for packet forwarding. This problem can be reduced to the well-known Steiner tree problem, which has proven to be NP-complete for deterministic link descriptors and cost functions. In this paper, we propose a novel multicast protocol, named heuristic algorithms for the solution of the Quality of Service (QoS constrained multicast routing problem, with incomplete information in Wireless Sensor Networks (WSN. As information aggregation or randomly fluctuating traffic loads, link measures are considered to be random variables. Simulation results show that the Hop Neural Networks (HNN based heuristics with a properly chosen additive measures can yield to a good solution for this traditionally NP complex problem, when compared to the best multicast algorithms known.

  4. Multicast routing with bandwidth and delay constraints based on genetic algorithms

    Directory of Open Access Journals (Sweden)

    Ahmed Younes

    2011-07-01

    Full Text Available Many multimedia communication applications require a source to send multimedia information to multiple destinations through a communication network. To support these applications, it is necessary to determine a multicast tree of minimal cost to connect the source node to the destination nodes subject to delay constraints on multimedia communication. This problem is known as multimedia multicast routing and has been proved to be NP-complete. The paper proposes a genetic algorithm for solving multimedia multicast routing, which find the low-cost multicasting tree with bandwidth and delay constraints. In the proposed algorithm, the k shortest paths from the source node to the destination nodes are used for genotype representation. The simulation results show that the proposed algorithm is able to find a better solution, fast convergence speed and high reliability. It can meet the real-time requirement in multimedia communication networks. The scalability and the performance of the algorithm with increasing number of network nodes are also quite encouraged.

  5. Secluding Efficient Geographic Multicast Protocol against Multicast Attacks

    Directory of Open Access Journals (Sweden)

    A. Amuthan

    2013-09-01

    Full Text Available A Mobile Ad-hoc Network (MANETs is composed of Mobile Nodes without any infrastructure. The network nodes in MANETs, not only act as ordinary network nodes but also as the routers for other peer devices. The dynamic topology, lack of a fixed infrastructure and the wireless nature make MANETs susceptible to the security attacks. To add to that, due to the inherent, severe constraints in power, storage and computational resources in the MANET nodes, incorporating sound defense mechanisms against such attacks is also non-trivial. Therefore, interest in research of Mobile Ad-hoc NETworks has been growing since last few years. Security is a big issue in MANETs as they are infrastructure-less and autonomous. The main objective of this paper is to address some basic security concerns in EGMP protocol which is a multicast protocol found to be more vulnerable towards attacks like blackhole, wormhole and flooding attacks. The proposed technique uses the concepts of certificate to prevent these attacks and to find the malicious node. These attacks are simulated using NS2.28 version and the proposed proactive technique is implemented. The following metrics like packet delivery ratio, control overhead, total overhead and End to End delay are used to prove that the proposed solution is secure and robust.

  6. Scalable Energy Efficient Location Aware Multicast Protocol for MANET (SEELAMP)

    CERN Document Server

    Kamboj, Pariza

    2010-01-01

    Multicast plays an important role in implementing the group communications in bandwidth scarce multihop mobile ad hoc networks. However, due to the dynamic topology of MANETs it is very difficult to build optimal multicast trees and maintaining group membership, making even more challenging to implement scalable and robust multicast in Mobile Ad hoc Networks (MANET). A scalable and energy efficient location aware multicast algorithm, called SEELAMP, for mobile ad hoc networks is presented in the paper that is based on creation of shared tree using the physical location of the nodes for the multicast sessions. It constructs a shared bi-directional multicast tree for its routing operations rather than a mesh, which helps in achieving more efficient multicast delivery. The algorithm uses the concept of small overlapped zones around each node for proactive topology maintenance with in the zone. Protocol depends on the location information obtained using a distributed location service, which effectively reduces th...

  7. On Satellite Multicast to Heterogeneous Receivers

    Science.gov (United States)

    2001-01-01

    combined into one bulk file. Let the multicast source use Reed-Solomon erasure ( RSE ) coding (e.g. [Mac97]) and let the bulk file be encoded into W ≥ 1... RSE -based FEC blocks. Each FEC block consists of h data packets and c parity packets – all of the same length. We assume a multicast tree that has a... RSE -based FEC block, a receiver must receive at least h distinct packets, either data or parity, from the same FEC block. To allow a systematic way

  8. Two Novel Tunnel-based Ring Protection Switching for MPLS-TP Multicast Services

    DEFF Research Database (Denmark)

    Zhang, Jiang; Fu, Rong; Yu, Hao;

    2011-01-01

    This paper investigates and compares the schemes suggested by the ITU and the IETF for MPLS-TP ring protection, and proposes two MPLS-TP ring protections to ensure reliability of MPLS-TP multicast services. The introduced ring protection schemes are named, the SPME-based-Wrapping protection scheme...... and the SPME-based-ROM-Wrapping protection scheme, both of which aim at retaining the advantages of previous MPSL-TP ring protections and avoiding limitations. In the paper, the requirements of designing an efficient and reliable MPLS-TP ring protection, for instance with respect to label consumption......, bandwidth utilization and operation complexity are well considered and also set concrete evaluating criteria for new proposed MPLS-TP ring protection schemes for multicast services....

  9. Providing resilience for carrier ethernet multicast traffic

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Wessing, Henrik; Zhang, Jiang

    2009-01-01

    This paper presents an overview of the Carrier Ethernet technology with specific focus on resilience. In particular, we detail how multicast traffic, which is essential for e.g. IPTV can be protected. We present Carrier Ethernet resilience methods for linear and ring networks and show by simulation...

  10. Hybrid Multicast Transmission for Public Safety Network in 5G

    Directory of Open Access Journals (Sweden)

    Fei Qi

    2016-01-01

    Full Text Available We investigate the application of wireless multicast technology in public safety network (PSN in future wireless communication system. The hybrid unicast/multicast transmission system is proposed and analyzed in 3D massive multi-input multioutput (MIMO channel. The mutual coupling channel model is adopted under the different antenna array configuration scenarios. The proposed hybrid system adopts multicast beamforming in the multicast groups as well as multiuser-MIMO (MU-MIMO linear precoding in the unicast group to increase system throughput. The null space method based interference cancellation is further performed between each group to eliminate signal leakage generated from each group. Comparisons between two types of antenna array configurations, different channel models, linear precoding as well as multicast beamforming, and user grouping strategies for multicast services are presented and analyzed by simulation.

  11. Cross-Layer Optimal Rate Allocation for Heterogeneous Wireless Multicast

    Directory of Open Access Journals (Sweden)

    Amr Mohamed

    2009-01-01

    Full Text Available Heterogeneous multicast is an efficient communication scheme especially for multimedia applications running over multihop networks. The term heterogeneous refers to the phenomenon when multicast receivers in the same session require service at different rates commensurate with their capabilities. In this paper, we address the problem of resource allocation for a set of heterogeneous multicast sessions over multihop wireless networks. We propose an iterative algorithm that achieves the optimal rates for a set of heterogeneous multicast sessions such that the aggregate utility for all sessions is maximized. We present the formulation of the multicast resource allocation problem as a nonlinear optimization model and highlight the cross-layer framework that can solve this problem in a distributed ad hoc network environment with asynchronous computations. Our simulations show that the algorithm achieves optimal resource utilization, guarantees fairness among multicast sessions, provides flexibility in allocating rates over different parts of the multicast sessions, and adapts to changing conditions such as dynamic channel capacity and node mobility. Our results show that the proposed algorithm not only provides flexibility in allocating resources across multicast sessions, but also increases the aggregate system utility and improves the overall system throughput by almost 30% compared to homogeneous multicast.

  12. A Heuristic Algorithm for QoS Multicast Routing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In recent years, QoS multicast routing has continued to be a very important research topic in the areas of net-works. This paper presents a heuristic algorithm for the QoS multicast routing (HAQMR). This heuristic algorithmdeals with delay and bandwidth constraints and has low cost. The HAQMR attempts to significantly reduce the overheadfor constructing a multicast tree. the proof for correctness of the HAQMR is given, and the performance of the HAQMRis evaluated by simulations. The study shows that HAQMR provides an available approach to QoS multicast routing.

  13. Efficient Multicast Support in High-Speed Packet Switches

    Directory of Open Access Journals (Sweden)

    Lotfi Mhamdi

    2007-06-01

    Full Text Available The tremendous growth of the Internet coupled with newly emerging applications has created a vital need for multicast traffic support by backbone routers and ATM switches. Considerable research work has been done on Input Queued (IQ switches to handle multicast traffic flows. Unfortunately, all previously proposed solutions were of no practical value because they either lack performance or were simply too complex to implement. Internally Buffered Crossbar (IBC switches, where a limited small amount of memory is added in each crosspoint of the crossbar fabric, on the other hand, have been considered as a robust alternative to buffer-less crossbar switches to improve the switching performance. However, very little has been done on multicasting in IBC switches. In this paper, we fill this gap and study the multicasting problem in IBC switches. In particular, we propose a novel IBC based multicast architecture along with a simple scheduling scheme named Multicast cross-point Round Robin (MXRR. Our scheme was shown to handle multicast traffic more efficiently and far better than all previous schemes for both the multicast FIFO architecture as well as the multicast k FIFO queues architecture. Yet, MXRR is both practical and achieves high performance.

  14. An Optimal Multicast Algorithm for Cube-Connected Cycles

    Institute of Scientific and Technical Information of China (English)

    宋建平; 侯紫峰; 史云涛

    2000-01-01

    This paper presents an efficient algorithm that implements oneto-many, or multicast, communication in one-port wormhole-routed cube-connected cycles (CCCs) in the absence of hardware multicast support. By exploiting the properties of the switching technology and the use of virtual channels, a minimumtime multicast algorithm is presented for n-dimensional CCCs that use deterministic routing of unicast messages. The algorithm can deliver a multicast message to m - 1destinations in [log2 m] message-passing steps, while avoiding contention among the constituent unicast messages. Performance results of a simulation study on CCCs with up to 10,240 nodes are also given.

  15. Energy Optimization for Wireless Sensor Networks using a Novel Dynamic Multicast Routing Protocol

    Directory of Open Access Journals (Sweden)

    S. Sundar Raj

    2014-07-01

    Full Text Available Minimization of energy consumption has always been the predominant factor deciding the acceptability of a routing protocol for wireless ad-hoc networks. In this study we have proposed a novel efficient multicast routing protocols in wireless mobile ad hoc networks is proposed. Due to the high mobility of nodes and highly dynamic topology, performing efficient and robust multicast in a Mobile Ad hoc Network (MANET is a challenging task. Most of existing multicast protocols in MANETs discover the routing path by flooding message over the whole network, which result in considerable cost for routing discovery and maintenance. Moreover, the reliability of the discovered path cannot be guaranteed, since the stabilities of nodes along such path are unpredictable. Here an attempt is made to devise an algorithm combining the features of both energy efficient and low latency algorithms. The new algorithm is intended to do well in real-world scenarios where the energy capacities of the nodes are not uniform. It employs a mobility prediction based election process to construct a reliable backbone structure performing packet transmission, message flooding, routing discovery and maintenance. Several virtual architectures are used in the protocol without need of maintaining state information for more robust and scalable membership management and packet forwarding in the presence of high network dynamics due to unstable wireless channels and node movements.

  16. Dynamic multicast traffic grooming in WDM networks

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiao-jun; GE Ning; FENG Chong-xi

    2006-01-01

    Dynamic multicast traffic grooming in wavelength division multiplexing (WDM) networks was analyzed to minimize networkwide costs and to increase the network resource utilization.A network model was developed for dynamic multicast traffic grooming with resource constraints and an algorithm that can provide quality of service (QoS)was proposed.The QoS is measured by the maximum number of lightpaths passing between the source and the destinations.The blocking probability of the algorithm was assessed in simulations.The results show that a higher QoS requirement results in higher blocking probability,and when the QoS requirement is low,changes in the QoS requirements have only small effects on the blocking probability.

  17. Performance optimization for multicast packet authentication

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In secure multicast, one of the challenging problems is the authentication of multicast packets. This paper presents a novel scheme to address this problem, which combines ideas in both the hash tree schemes and the hash chain schemes. In this scheme, a group of packets is partitioned into equal-sized subgroups. Then a Merkle hash tree is built for each subgroup of packets, and the hash value of every root is appended to preceding packets to form hash chains. Its performance is analyzed and simulated using Biased Coin Toss loss model and 2-state Markov Chain loss model, respectively. Compared with the original hash chain schemes, results show that this scheme is much more efficient in term of communication overhead.

  18. Tunable Sparse Network Coding for Multicast Networks

    DEFF Research Database (Denmark)

    Feizi, Soheil; Roetter, Daniel Enrique Lucani; Sørensen, Chres Wiant

    2014-01-01

    complexity. At the end of a transmission, when receivers have accumulated degrees of freedom, coding density is increased. We propose a family of tunable sparse network codes (TSNCs) for multicast erasure networks with a controllable trade-off between completion time performance to decoding complexity...... a mechanism to perform efficient Gaussian elimination over sparse matrices going beyond belief propagation but maintaining low decoding complexity. Supporting simulation results are provided showing the trade-off between decoding complexity and completion time....

  19. Scalable Overlay Multicasting in Mobile Ad Hoc Networks (SOM

    Directory of Open Access Journals (Sweden)

    Pariza Kamboj

    2010-10-01

    Full Text Available Many crucial applications of MANETs like the battlefield, conference and disaster recovery defines the needs for group communications either one-to-many or many-to-many form. Multicast plays an important role in bandwidth scarce multihop mobile ad hoc networks comprise of limited battery power mobile nodes. Multicast protocols in MANETs generate many controls overhead for maintenance of multicast routingstructures due to frequent changes of network topology. Bigger multicast tables for the maintenance of network structures resultsin inefficient consumption of bandwidth of wireless links andbattery power of anemic mobile nodes, which in turn, pose thescalability problems as the network size is scaled up. However,many MANET applications demands scalability from time to time. Multicasting for MANETs, therefore, needs to reduce the state maintenance. As a remedy to these shortcomings, this paper roposes an overlay multicast protocol on application layer. In the proposed protocol titled “Scalable Overlay Multicasting in Mobile Ad Hoc Networks (SOM” the network nodes construct overlay hierarchical framework to reduce the protocols states and constrain their distribution within limited scope. Based on zone around each node, it constructs a virtual structure at application layer mapped with the physical topology at network layer, thus formed two levels of hierarchy. The concept of two level hierarchies reduces the protocol state maintenance and hence supports the vertical scalability. Protocol depends on the location information obtained using a distributed location service, which effectively reduces the overhead for route searching and updating the source based multicast tree.

  20. Joint NC-ARQ and AMC for QoS-Guaranteed Mobile Multicast

    Directory of Open Access Journals (Sweden)

    Schwefel Hans-Peter

    2010-01-01

    Full Text Available In mobile multicast transmissions, the receiver with the worst instantaneous channel condition limits the transmission data rate under the desired Quality-of-Service (QoS constraints. If Automatic Repeat reQuest (ARQ schemes are applied, the selection of Adaptive Modulation and Coding (AMC mode will not necessarily be limited by the worst channel anymore, and improved spectral efficiency may be obtained in the efficiency-reliability tradeoff. In this paper, we first propose a Network-Coding-based ARQ (NC-ARQ scheme in its optimal form and suboptimal form (denoted as Opt-ARQ and SubOpt-ARQ, resp. to solve the scalability problem of applying ARQ in multicast. Then we propose two joint NC-ARQ-AMC schemes, namely, the Average PER-based AMC (AvgPER-AMC with Opt-ARQ and AvgPER-AMC with SubOpt-ARQ in a cross-layer design framework to maximize the average spectral efficiency per receiver under specific QoS constraints. The performance is analyzed under Rayleigh fading channels for different group sizes, and numerical results show that significant gains in spectral efficiency can be achieved with the proposed joint NC-ARQ-AMC schemes compared with the existing multicast ARQ and/or AMC schemes.

  1. Secure Multicast Routing Algorithm for Wireless Mesh Networks

    Directory of Open Access Journals (Sweden)

    Rakesh Matam

    2016-01-01

    Full Text Available Multicast is an indispensable communication technique in wireless mesh network (WMN. Many applications in WMN including multicast TV, audio and video conferencing, and multiplayer social gaming use multicast transmission. On the other hand, security in multicast transmissions is crucial, without which the network services are significantly disrupted. Existing secure routing protocols that address different active attacks are still vulnerable due to subtle nature of flaws in protocol design. Moreover, existing secure routing protocols assume that adversarial nodes cannot share an out-of-band communication channel which rules out the possibility of wormhole attack. In this paper, we propose SEMRAW (SEcure Multicast Routing Algorithm for Wireless mesh network that is resistant against all known active threats including wormhole attack. SEMRAW employs digital signatures to prevent a malicious node from gaining illegitimate access to the message contents. Security of SEMRAW is evaluated using the simulation paradigm approach.

  2. Multicast Routing Problem Using Tree-Based Cuckoo Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Mahmood Sardarpour

    2016-06-01

    Full Text Available The problem of QoS multicast routing is to find a multicast tree with the least expense/cost which would meet the limitations such as band width, delay and loss rate. This is a NP-Complete problem. To solve the problem of multicast routing, the entire routes from the source node to every destination node are often recognized. Then the routes are integrated and changed into a single multicast tree. But they are slow and complicated methods. The present paper introduces a new tree-based optimization method to overcome such weaknesses. The recommended method directly optimizes the multicast tree. Therefore a tree-based typology including several spanning trees is created which combines the trees two by two. For this purpose, the Cuckoo Algorithm is used which is proved to be well converged and makes quick calculations. The simulation conducted on different types of network typologies proved that it is a practical and influential algorithm.

  3. A Heuristic Algorithm for Core Selection in Multicast Routing

    Institute of Scientific and Technical Information of China (English)

    Manas Ranjan Kabat; Manoj Kumar Patel; Chita Ranjan Tripathy

    2011-01-01

    With the development of network multimedia technology,more and more real-time multimedia applications need to transmit information using multicast.The basis of multicast data transmission is to construct a multicast tree.The main problem concerning the construction of a shared multicast tree is selection of a root of the shared tree or the core point.In this paper,we propose a heuristic algorithm for core selection in multicast routing.The proposed algorithm selects core point by considering both delay and inter-destination delay variation.The simulation results show that the proposed algorithm performs better than the existing algorithms in terms of delay variation subject to the end-to-end delay bound.The mathematical time complexity and the execution time of the proposed algorithm are comparable to those of the existing algorithms.

  4. Link-Aware Nice Application Level Multicast Protocol

    Directory of Open Access Journals (Sweden)

    Dina Helal

    2014-06-01

    Full Text Available Multicast is one of the most efficient ways to distribute data to multiple users. There are different types of Multicast such as IP Multicast, Overlay Multicast, and Application Layer Multicast (ALM. In this paper, we present a link-aware Application Layer (ALM Multicast algorithm. Our proposed algorithm, Link Aware-NICE (LA-NICE [1], is an enhanced version of the NICE protocol [2]. LA-NICE protocol uses the variations of bandwidth or capacity in communication links to improve multicast message delivery and minimize end-to-end delay. OMNeT++ simulation frame work [3] was used to evaluate LA-NICE. The evaluation is done through a comparison between LA-NICE and NICE. The simulation results showed that LA-NICE produces an increased percentage of success ful message delivery ranging from 2% to 10% compared to NICE. Also, LA-NICE has less average delay and less average message hop count than NICE which reduces the overall latency of message delivery.

  5. An Economic Case for End System Multicast

    Science.gov (United States)

    Analoui, Morteza; Rezvani, Mohammad Hossein

    This paper presents a non-strategic model for the end-system multicast networks based on the concept of replica exchange economy. We believe that microeconomics is a good candidate to investigate the problem of selfishness of the end-users (peers) in order to maximize the aggregate throughput. In this solution concept, the decisions that a peer might make, does not affect the actions of the other peers at all. The proposed mechanism tunes the price of the service in such a way that general equilibrium holds.

  6. A multicast dynamic wavelength assignment algorithm based on matching degree

    Institute of Scientific and Technical Information of China (English)

    WU Qi-wu; ZHOU Xian-wei; WANG Jian-ping; YIN Zhi-hong; ZHANG Long

    2009-01-01

    The wavelength assignment with multiple multicast requests in fixed routing WDM network is studied. A new multicast dynamic wavelength assignment algorithm is presented based on matching degree. First, the wavelength matching degree between available wavelengths and multicast routing trees is introduced into the algorithm. Then, the wavelength assign-ment is translated into the maximum weight matching in bipartite graph, and this matching problem is solved by using an extended Kuhn-Munkres algorithm. The simulation results prove that the overall optimal wavelength assignment scheme is obtained in polynomial time. At the same time, the proposed algorithm can reduce the connecting blocking probability and improve the system resource utilization.

  7. Cooperative relay-based multicasting for energy and delay minimization

    KAUST Repository

    Atat, Rachad

    2012-08-01

    Relay-based multicasting for the purpose of cooperative content distribution is studied. Optimized relay selection is performed with the objective of minimizing the energy consumption or the content distribution delay within a cluster of cooperating mobiles. Two schemes are investigated. The first consists of the BS sending the data only to the relay, and the second scheme considers the scenario of threshold-based multicasting by the BS, where a relay is selected to transmit the data to the mobiles that were not able to receive the multicast data. Both schemes show significant superiority compared to the non-cooperative scenarios, in terms of energy consumption and delay reduction. © 2012 IEEE.

  8. Refinement of the canine CD1 locus topology and investigation of antibody binding to recombinant canine CD1 isoforms

    DEFF Research Database (Denmark)

    Schjaerff, Mette; Keller, Stefan M; Fass, Joseph;

    2016-01-01

    CD1 molecules are antigen-presenting glycoproteins primarily found on dendritic cells (DCs) responsible for lipid antigen presentation to CD1-restricted T cells. Despite their pivotal role in immunity, little is known about CD1 protein expression in dogs, notably due to lack of isoform-specific a......CD1 molecules are antigen-presenting glycoproteins primarily found on dendritic cells (DCs) responsible for lipid antigen presentation to CD1-restricted T cells. Despite their pivotal role in immunity, little is known about CD1 protein expression in dogs, notably due to lack of isoform......-specific antibodies. The canine (Canis familiaris) CD1 locus was previously found to contain three functional CD1A genes: canCD1A2, canCD1A6, and canCD1A8, where two variants of canCD1A8, canCD1A8.1 and canCD1A8.2, were assumed to be allelic variants. However, we hypothesized that these rather represented two...... recognized canine CD1a8 and CD1a9 isoforms, and Fe1.5F4 mAb solely recognized canine CD1a6. Anti-CD1b mAbs recognized the canine CD1b protein, but also bound CD1a2, CD1a8, and CD1a9. Interestingly, Ca9.AG5 showed allele specificity based on a single nucleotide polymorphism (SNP) located at position 321. Our...

  9. Application of Multicasting in Surveillance Systems%多播在数字监控系统中的应用

    Institute of Scientific and Technical Information of China (English)

    苏士美; 李海芳

    2003-01-01

    This paper discusses problems of multicasting and its application. Two ways are proposed to overcome theproblems of multicasting according to the architectures of current networks and the functional requirements of asurveillance System. One is that Winsock API is directly used to implement multicasting on a network supportingmulticasting. The other adopts the technology of proxy server and tunneling on a network not supporting multicast-ing. In addition,this paper discusses some techniques of multicasting,such as sending,resending,auto-adjusting withthe change of the transmission quality of networks,and the management of multicast group and multicast addresses.

  10. Performance Evaluation of Multicast Video Distribution using LTE-A in Vehicular Environments

    OpenAIRE

    Thota, Jayashree; Bulut, Berna; Doufexi, Angela; Armour, Simon; Nix, Andrew

    2017-01-01

    Application Layer Forward Error Correction (AL-FEC) based on Raptor codes has been employed in Multimedia Broadcast/Multicast Services (MBMS) to improve reliability. This paper considers a cross-layer system based on the latest Raptor Q codes for transmitting high data rate video. Multiple Input Multiple Output (MIMO) channels in a realistic outdoor environment for a user moving at 50kmph in an LTE-A system is considered. A link adaptation model with optimized cross-layer parameters is propos...

  11. SOME NOTES ON COST ALLOCATION IN MULTICASTING

    Directory of Open Access Journals (Sweden)

    Darko Skorin-Kapov

    2012-12-01

    Full Text Available We analyze the cost allocation strategies with the problef of broadcasting information from some source to a number of communication network users. A multicast routing chooses a minimum cost tree network that spans the source and all the receivers. The cost of such a network is distributed among its receivers who may be individuals or organizations with possibly conflicting interests. Providing network developers, users and owners with practical computable 'fair' cost allocation solution procedures is of great importance for network mamagement. Consequently, this multidisciplinary problem was extensively studied by Operational Researchers, Economists, Mathematicians and Computer Scientists. The fairness of various proposed solutions was even argued in US courts. This presentation overviews some previously published, as well as some recent results, in the development of algorithmic mechanisms to efficiently compute 'attractive' cost allocation solutions for multicast networks. Specifically, we will analyze cooperative game theory based cost allocation models that avoid cross subsidies and/or are distance and population monotonic. We will also present some related open cost allocation problems and the potential contribution that such models might make to this problem in the future.

  12. A Novel Approach for Core Selection in Shared Tree Multicasting

    Directory of Open Access Journals (Sweden)

    Bidyut Gupta

    2014-03-01

    Full Text Available Multicasting is preferred over multiple unicasts from the viewpoint of better utilization of network bandwidth. Multicasting can be done in two different ways: source based tree approach and shared tree approach. Protocols such as Core Based Tree (CBT, Protocol Independent Multicasting Sparse Mode (PIM-SM use shared treeapproach. Shared tree approach is preferred over source-based tree approach because in the later construction of minimum cost treeper source is needed unlike a single shared tree in the former approach.The work presented in this paper provides an efficient core selection method for shared tree multicasting. In this work, we have used a new concept known as pseudo diameter for core selection. The presented methodselects more than one core to achieve fault tolerance

  13. Efficient Resource Management for Multicast Ad Hoc Networks: Survey

    Directory of Open Access Journals (Sweden)

    Amit Chopra

    2016-09-01

    Full Text Available Group communication over multicast ad hoc network suffers from insufficient utilization of limited resources, i.e. shared channel, battery, data processing capabilities and storage space etc. Multicast routing protocol should be able to manage all these resources because their consumption depends upon different factors, i.e. Unicast/Multicast network operations, dynamic topology due to mobility, control overhead due to scalability, packet loss and retransmission due to collision and congestion etc. All these factors may cause unnecessary network load, delay and unfair resource utilization. However, multicast ad hoc routing protocols are more efficient than Unicast routing protocols, but they also suffer from performance degradation factors discussed above. Researchers have developed various layer wise solutions for resource optimization. In this paper, we will explore the different schemes for fair utilization of network resources.

  14. Mobile Multicast in Hierarchical Proxy Mobile IPV6

    Science.gov (United States)

    Hafizah Mohd Aman, Azana; Hashim, Aisha Hassan A.; Mustafa, Amin; Abdullah, Khaizuran

    2013-12-01

    Mobile Internet Protocol Version 6 (MIPv6) environments have been developing very rapidly. Many challenges arise with the fast progress of MIPv6 technologies and its environment. Therefore the importance of improving the existing architecture and operations increases. One of the many challenges which need to be addressed is the need for performance improvement to support mobile multicast. Numerous approaches have been proposed to improve mobile multicast performance. This includes Context Transfer Protocol (CXTP), Hierarchical Mobile IPv6 (HMIPv6), Fast Mobile IPv6 (FMIPv6) and Proxy Mobile IPv6 (PMIPv6). This document describes multicast context transfer in hierarchical proxy mobile IPv6 (H-PMIPv6) to provide better multicasting performance in PMIPv6 domain.

  15. A Proactive Tree Recovery Mechanism for Resilient Overlay Multicast

    Directory of Open Access Journals (Sweden)

    Poorna Satyanarayana B.

    2012-06-01

    Full Text Available Overlay multicast constructs a multicast delivery tree among end hosts. An important problem for making overlay multicast more dependable is how to recover from node departures in order to minimize the disruption of service to those affected nodes. In this paper, we propose a proactive tree recovery mechanism to make the overlay multicast resilient to these failures and unexpected events. The salient feature of the approach is that rescue plans for multiple non-leaf nodes can work together for their respective children when they fail or leave at the same time. Extensive simulations demonstrate that our proactive approach can recover from node departures much faster than reactive methods, while the quality of trees restored and the cost of recovery are reasonable

  16. SPHERE: a scalable multicast framework in overlay networks

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper presents Sphere, a scalable multicast framework in overlay network. Sphere is a highly efficient, self-organizing and robust multicast protocol overlayed on the Internet. The main contributions of this paper are twofold. First, Sphere organizes the control topology of overlay network in two directions: horizontal and vertical. The horizontal meshes are used to locate and organize hosts in tracks, and the vertical meshes are used to manage the data paths between tracks. Second, Sphere balances stress and stretch of the overlay network by assigning hosts into different tracks and clusters. This structure distributes stress on the multicast trees uniformly, and meantime makes path stretch as small as possible.Simulations results show that Sphere can support multicast with large group size and has good performance on organizing meshes and building data delivery trees.

  17. QOS-BASED MULTICAST ROUTING OPTIMIZATION ALGORITHMS FOR INTERNET

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Most of the multimedia applications require strict Quality-of-Service (QoS) guarantee during the communication between a single source and multiple destinations. The paper mainly presents a QoS Multicast Routing algorithms based on Genetic Algorithm (QMRGA). Simulation results demonstrate that the algorithm is capable of discovering a set of QoS-based near optimized, non-dominated multicast routes within a few iterations, even for the networks environment with uncertain parameters.

  18. Using IGMP V3 for controllable multicast over EPON

    Science.gov (United States)

    Zhang, Chuanhao; Liu, Deming; Zhang, Li; Wu, Guangsheng

    2008-11-01

    The character of 1Gbps bandwidth and tree-based structure make EPON very suitable for broadcast or multicast services such as IPTV. The document proposed a novel scheme, based on the former research for controllable multicast over EPON system, mainly considering system security and maintainability. It can both control the IPTV program source's and the receiver's validity, improving the efficiency and precision. The processing of the two configurations mode is given in detail.

  19. Secure Group Communications for Large Dynamic Multicast Group

    Institute of Scientific and Technical Information of China (English)

    Liu Jing; Zhou Mingtian

    2003-01-01

    As the major problem in multicast security, the group key management has been the focus of research But few results are satisfactory. In this paper, the problems of group key management and access control for large dynamic multicast group have been researched and a solution based on SubGroup Secure Controllers (SGSCs) is presented, which solves many problems in IOLUS system and WGL scheme.

  20. Transmission techniques for emergent multicast and broadcast systems

    CERN Document Server

    da Silva, Mario Marques; Dinis, Rui; Souto, Nuno; Silva, Joao Carlos

    2010-01-01

    Describing efficient transmission schemes for broadband wireless systems, Transmission Techniques for Emergent Multicast and Broadcast Systems examines advances in transmission techniques and receiver designs capable of supporting the emergent wireless needs for multimedia broadcast and multicast service (MBMS) requirements. It summarizes the research and development taking place in wireless communications for multimedia MBMS and addresses the means to improved spectral efficiency to allow for increased user bit rate, as well as increased capacity of the digital cellular radio network.The text

  1. Key Management for Secure Multicast over IPv6 Wireless Networks

    Directory of Open Access Journals (Sweden)

    Siddiqi Mohammad Umar

    2006-01-01

    Full Text Available Multicasting is an efficient method for transmission and routing of packets to multiple destinations using fewer network resources. Along with widespread deployment of wireless networks, secure multicast over wireless networks is an important and challenging goal. In this paper, we extend the scope of a recent new key distribution scheme to a security framework that offers a novel solution for secure multicast over IPv6 wireless networks. Our key management framework includes two scenarios for securely distributing the group key and rekey messages for joining and leaving a mobile host in secure multicast group. In addition, we perform the security analysis and provide performance comparisons between our approach and two recently published scenarios. The benefits of our proposed techniques are that they minimize the number of transmissions required to rekey the multicast group and impose minimal storage requirements on the multicast group. In addition, our proposed schemes are also very desirable from the viewpoint of transmission bandwidth savings since an efficient rekeying mechanism is provided for membership changes and they significantly reduce the required bandwidth due to key updating in mobile networks. Moreover, they achieve the security and scalability requirements in wireless networks.

  2. UNICAST FORWARDED MULTI-SOURCE MULTICAST ROUTING PROTOCOL FOR MANET

    Directory of Open Access Journals (Sweden)

    J. Rangarajan

    2013-03-01

    Full Text Available In mobile ad hoc network, nodes co-operatively form a network independent of any fixed base station infrastructure. Every node in a mobile ad-hoc network can function as a router and forwards the data packets to the other nodes. Multicasting plays an important role whenever group communications are required. Most of the existing multicast routing protocols in mobile ad hoc networks consider only one source in a multicast group and become inefficient when the protocol is extended to multi-source multicasting. In this paper, we propose a unicast forwarded multi-source multicast routing protocol, for ad hoc networks which is having more than one source in a group. Here, the sources of the group also act as a receiver for other sources in that group. The proposed routing method is a cluster based one and avoids the flooding or broadcasting of control packets to form routing structure. On executing source joining and receiver joining procedures, a complete path for multicast data transfer was established. As the join request control packets are forwarded only through cluster-heads and junction nodes, lower amount of control overhead is incurred. Simulation result shows that the proposed protocol maintains the delivery ratio with reduced control overhead and utilizes the bandwidth efficiently.

  3. Network coding for multi-resolution multicast

    DEFF Research Database (Denmark)

    2013-01-01

    A method, apparatus and computer program product for utilizing network coding for multi-resolution multicast is presented. A network source partitions source content into a base layer and one or more refinement layers. The network source receives a respective one or more push-back messages from one...... or more network destination receivers, the push-back messages identifying the one or more refinement layers suited for each one of the one or more network destination receivers. The network source computes a network code involving the base layer and the one or more refinement layers for at least one...... of the one or more network destination receivers, and transmits the network code to the one or more network destination receivers in accordance with the push-back messages....

  4. Multicast Protocol for Uni-Directional Networks

    Institute of Scientific and Technical Information of China (English)

    黄皓; 陈贵海; 谢立; 孙钟秀

    2000-01-01

    A very inexpensive receive-only satellite receiver can receive high bandwidth traffic from a feeder. Therefore the connection between the feeder and the receiver is uni-directional. The existing routing protocols, such as Link-State and Distance-Vector, are designed on the premise that any links are bidirectional and they cannot handle the uni-directional links. In this paper, a dynamic multicast routing protocol is proposed, which can handle uni-directional networks. This protocol can also adapt to the dynamic change of the topology of the network and has good scalability. A formal description of the protocol by Petri net is given. Liveness,deadlock free and other properties of the protocol are proved.

  5. Multicast Routing Based on Hybrid Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    CAO Yuan-da; CAI Gui

    2005-01-01

    A new multicast routing algorithm based on the hybrid genetic algorithm (HGA) is proposed. The coding pattern based on the number of routing paths is used. A fitness function that is computed easily and makes algorithm quickly convergent is proposed. A new approach that defines the HGA's parameters is provided. The simulation shows that the approach can increase largely the convergent ratio, and the fitting values of the parameters of this algorithm are different from that of the original algorithms. The optimal mutation probability of HGA equals 0.50 in HGA in the experiment, but that equals 0.07 in SGA. It has been concluded that the population size has a significant influence on the HGA's convergent ratio when it's mutation probability is bigger. The algorithm with a small population size has a high average convergent rate. The population size has little influence on HGA with the lower mutation probability.

  6. Protocol Independent Multicast Based States Allocation

    Directory of Open Access Journals (Sweden)

    G Hemalatha

    2012-02-01

    Full Text Available In this paper the Protocol Independent Multicast (PIM protocol is being used. The PIM protocol avoids the packet drop and diverting problem. The PIM protocol is not dependent on any specific unicast routing protocol. It is IP routing independent protocol. The PIM uses the unicast and multicast information to create a distribution tree along the reverse path from the receivers towards the source. The PIM protocol consists of three modes such as sparse mode, dense mode and bidirectional mode. The sparse mode is used to sends the file from router to a receiver. The dense mode is used to sends the file from router to multiple receivers. The bidirectional mode is used to sends the message from router to sender and then continue the other process depending on the sender requirements. The client sends the file from sender to destination via the router. First the sender selects the file name and receiver name for transmission. Then the state is assigned automatically depend upon the user selection. The state can be defined by the number of destination selected to transmit the file from the source. If the sender selects single destination, it will assign “Without forwarding state router” for transmission. Otherwise it will assign “Forwarding state router” for transmission. If the receiver is not available, the router sends a message to sender such that “the requested receiver is not available”. Then the client will decide the file is transfer or not, it will reply with transfer the file, then the file will be transferred until the file will be discarded at client side. If the sender tries the same process after two times, the router will display the warning message as “the requested receiver is not available, this file will be discarded at client side”. Then it continues the other process.

  7. Cost-Effective and Fast Handoff Scheme in Proxy Mobile IPv6 Networks with Multicasting Support

    Directory of Open Access Journals (Sweden)

    Illkyun Im

    2014-01-01

    Full Text Available With recent advancements in wireless communication technologies, mobile multicasting is becoming important, in an effort to use network resources more efficiently. In the past, when various mobile IP-based multicast techniques were proposed, the focus was on the costs needed for network delivery to provide multicast services, as well as on minimizing the multicast handover delay. However, it is fundamentally difficult to resolve the problems of handover delay and tunnel convergence for techniques using MIPv6 (Mobile IPv6, a host-based mobility management protocol. To resolve these problems, the network-based mobility management protocol PMIPv6 (Proxy Mobile IPv6 was standardized. Although performance is improved in PMIPv6 over MIPv6, it still suffers from problems of handover delay and tunnel convergence. To overcome these limitations, a technique called LFH (Low-cost and Fast Handoff is proposed in this paper, for fast and low-cost mobility management with multicasting support in PMIPv6 networks. To reduce the interactions between the complex multicast routing protocol and multicast messages, a simplified proxy method called MLD (Multicast Listener Discovery is implemented and modified. Furthermore, a TCR (Tunnel Combination and Reconstruction algorithm was used in the multicast handover procedure within the LMA (Local Mobility Anchor domain, as well as in the multicast handover procedure between domains, in order to overcome the problem of tunnel convergence. It was found that, compared to other types of multicast techniques, LFH reduces multicast delay, and requires lower cost.

  8. IP over optical multicasting for large-scale video delivery

    Science.gov (United States)

    Jin, Yaohui; Hu, Weisheng; Sun, Weiqiang; Guo, Wei

    2007-11-01

    In the IPTV systems, multicasting will play a crucial role in the delivery of high-quality video services, which can significantly improve bandwidth efficiency. However, the scalability and the signal quality of current IPTV can barely compete with the existing broadcast digital TV systems since it is difficult to implement large-scale multicasting with end-to-end guaranteed quality of service (QoS) in packet-switched IP network. China 3TNet project aimed to build a high performance broadband trial network to support large-scale concurrent streaming media and interactive multimedia services. The innovative idea of 3TNet is that an automatic switched optical networks (ASON) with the capability of dynamic point-to-multipoint (P2MP) connections replaces the conventional IP multicasting network in the transport core, while the edge remains an IP multicasting network. In this paper, we will introduce the network architecture and discuss challenges in such IP over Optical multicasting for video delivery.

  9. Performance analysis of optical multicast in a new switching structure

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The emergence of new services demands multicast function in optical network.Because of the high cost and complex architecture of multicast capable (MC) node, splitter-sharing switch structure is introduced in which the light splitters are shared by all input signals.To accommodate to this situation, by extending resource ReSerVation protocol-traffic engineering (RSVP-TE) and open shortest path first-traffic engineering (OSPF-TE), a new optical multicast mechanism is provided and the signaling flow and its finite state machine model are given.At the same time, a multicast routing algorithm in splitter-sharing optical network and a changing link weight policy to balance network traffic are proposed.Simulations in NSFNET show no matter with or without wavelength converters, when the number of splitters is 25% of that demanded by traditional MC nodes, the multicast performance has been close to the ideal circumstance.Wavelength converters and changing link weight help much in improving the traffic performance when the number of splitters is adequate.

  10. Mobility based multicast routing in wireless mesh networks

    Science.gov (United States)

    Jain, Sanjeev; Tripathi, Vijay S.; Tiwari, Sudarshan

    2013-01-01

    There exist two fundamental approaches to multicast routing namely minimum cost trees and shortest path trees. The (MCT's) minimum cost tree is one which connects receiver and sources by providing a minimum number of transmissions (MNTs) the MNTs approach is generally used for energy constraint sensor and mobile ad hoc networks. In this paper we have considered node mobility and try to find out simulation based comparison of the (SPT's) shortest path tree, (MST's) minimum steiner trees and minimum number of transmission trees in wireless mesh networks by using the performance metrics like as an end to end delay, average jitter, throughput and packet delivery ratio, average unicast packet delivery ratio, etc. We have also evaluated multicast performance in the small and large wireless mesh networks. In case of multicast performance in the small networks we have found that when the traffic load is moderate or high the SPTs outperform the MSTs and MNTs in all cases. The SPTs have lowest end to end delay and average jitter in almost all cases. In case of multicast performance in the large network we have seen that the MSTs provide minimum total edge cost and minimum number of transmissions. We have also found that the one drawback of SPTs, when the group size is large and rate of multicast sending is high SPTs causes more packet losses to other flows as MCTs.

  11. Enhanced power saving mechanism for supporting multicast services in 802.11 wireless LANs

    Institute of Scientific and Technical Information of China (English)

    Yong HE; Rui-xi YUAN; Xiao-jun MA; Jun LI

    2009-01-01

    Traditional 802. 11 power saving mechanism (PSM) treats multicast and broadcast traffic equally, and suffers significant performance degradation with multicast background traffic. This paper proposes an enhanced PSM that effectively differentiates multicast streams. It re-arranges the virtual bitmap of the traffic indication map (TIM) to carry traffic status for multicast groups and introduces a concept of sequential transmission of multi-addressed data to facilitate differentiation among multicast groups. Our analysis shows that the enhanced PSM can effectively save power in mixed traffic environments.

  12. Cellular endocytic compartment localization of expressed canine CD1 molecules

    DEFF Research Database (Denmark)

    Schjærff, Mette; Keller, Stefan M.; Affolter, Verena K.

    2016-01-01

    CD1 molecules are glycoproteins present primarily on dendritic cells (DCs), which recognize and presenta variety of foreign- and self-lipid antigens to T-cells. Humans have five different CD1 isoforms that sur-vey distinct cellular compartments allowing for recognition of a large repertoire...... onlya diminished GFP expression. In conclusion, canine CD1 transfectants show distinct localization patternsthat are similar to human CD1 proteins with the exception of the canine CD1d isoform, which most likelyis non-functional. These findings imply that canine CD1 localization overall resembles human...... CD1 traf-ficking patterns. This knowledge is important for the understanding of lipid antigen-receptor immunityin the dog....

  13. Multicast Address Management and Connection Control Based on Hierarchical Autonomous Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Jian; ZHANG Fuyan

    1999-01-01

    Multicast capability, including multicast address and multicast routing mechanisms, at the network layeris necessary in order to reduce the bandwidth requirements of multiparty, multicast applications. Based on hierarchical autonomous structure in accordance with the self-organization topologies of Internet, the paper puts forward a multicast address management scheme that is shown to be robust and scalable. Connection control hierarchy (CCH) based on master/slave relationship and a simple efficient building algorithm of multi-point connection is also built. The paper also describes the normal operations of multicast address management andmulti-point connection controller. Through simulation experiment, HAM, CM and DDM of Multicast Address Allocation are compared. HAM integrates the merits of CM and DDM, which is efficient as a whole, robust andscalable. CCH raises the efficiency of connection control, and is highly robust, flexible and scalable.

  14. Multicasting along Energy—Efficient Meshes in Mobile Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    JIANGHai; CHENGShixin; HEYongming

    2003-01-01

    In consideration that current mesh-based multicast routing protocols for mobile ad hoc networks don't tend to form energy-efficient multicast infrastruc-ture, we propose a new Energy-efficient multicast rout-ing protocol (E2MRP) for mobile ad hoc networks. The two main characteristics of E2MRP are: (1) using in turn the criteria for minimum energy consumed per packet and minimum maximum node cost during the course of relaying group (RG) creation and maintenance; (2)forming a graph-based multicast infrastructure instead of a tree-based one. Compared to multicast incremen-tal power (MIP) and on-demand multicast routing pro-tocol (ODMRP), as the simulation results show, E2MRP tremendously reduces the energy consumption rate of nodes and hence prolongs the lifetime of nodes and net-works, especially when the size of multicast group is small and node mobility is low.

  15. New multicast authentication protocol for entrusted members using advanced encryption standard

    Directory of Open Access Journals (Sweden)

    Reham Abdellatif Abouhogail

    2011-12-01

    Full Text Available Today there is a widening in digital technologies and increasing in new multimedia services like: pay-per-view TV, interactive simulations, teleconferencing. So there is an increasing demand for multicast communication. There is a number of security issues in multicast communication directly related to the specific nature of multicast. In this paper, we propose a new scheme for authenticating streamed data delivered in real-time over an insecure network, and we concentrate on the multicast authentication problem. Important requirements of multicast communication protocols are: to perform authentication in real-time, to resist packet loss and to have low communication and computation overheads. In this paper, a new multicast authentication scheme is proposed. It is suitable for real time applications. It uses the advanced encryption standard algorithm to solve the problem of entrusted members. This scheme uses the idea of the new index number each time the member sends certain block of packets in the multicast group.

  16. Reformative multicast routing protocol based on Ad Hoc

    Institute of Scientific and Technical Information of China (English)

    杨喜旺; 王华; 焦国太

    2008-01-01

    Mobile Ad Hoc networks has been widely applied to military field, emergency management, public service and so on. Because it is uncertain on network and communication, a great deal of energy will be consumed with nodes increasing and creating routing each other. The reformative on-demand multicast routing protocol was putted forward by researching the energy consuming of multicast routing protocol in Ad Hoc. It will decrease consumption in a big multicast flooding through studying the relaying group net structure based on map or wormhole. The energy consumption is reduced 30% by creating the two kinds of routing principles: minimization of energy consumption and minimization of maximum nodes energy consumption. The simulation result indicates that the reformative RODMRP is effective to reduce the energy consuming while routing protocol built.

  17. Efficient Non-Repudiation Multicast Source Authentication Schemes

    Institute of Scientific and Technical Information of China (English)

    李先贤; 怀进鹏

    2002-01-01

    In secure multicast communication, packet source authentication is a bot-tleneck problem due to the dynamic property of the multicast group, unreliability of datatransmission and the large number of data packets. This paper proposes a novel authentica-tion scheme called B-MSAS (Balance Multicast Source Authentication Scheme) that can beused to solve this problem, in which a new message authentication technique is introduced.This scheme dramatically reduces the signature size overhead and raises the signature rate. Itprovides the non-repudiation service, high loss resistance, and can easily be scaled up to poten-tially millions of receivers, and hence has a sweeping applicability. It should have applicationsto many practical problems.

  18. Algorithm for Delay-Constrained Minimal Cost Group Multicasting

    Institute of Scientific and Technical Information of China (English)

    SUN Yugeng; WANG Yanlin; YAN Xinfang

    2005-01-01

    Group multicast routing algorithms satisfying quality of service requirements of real-time applications are essential for high-speed networks. A heuristic algorithm was presented for group multicast routing with bandwidth and delay constrained. A new metric was designed as a function of available bandwidth and delay of link. And source-specific routing trees for each member were generated in the algorithm by using the metric, which satisfy member′s bandwidth and end-to-end delay requirements. Simulations over random network were carried out to compare the performance of the proposed algorithm with that from literature.Experimental results show that the algorithm performs better in terms of network cost and ability in constructing feasible multicast trees for group members. Moreover,the algorithm can avoid link blocking and enhance the network behavior efficiently.

  19. Application layer multicast routing solution based on genetic algorithms

    Institute of Scientific and Technical Information of China (English)

    Peng CHENG; Qiufeng WU; Qionghai DAI

    2009-01-01

    Application layer multicast routing is a multi-objective optimization problem.Three routing con-straints,tree's cost,tree's balance and network layer load distribution are analyzed in this paper.The three fitness functions are used to evaluate a multicast tree on the three indexes respectively and one general fitness function is generated.A novel approach based on genetic algorithms is proposed.Numerical simulations show that,compared with geometrical routing rules,the proposed algorithm improve all three indexes,especially on cost and network layer load distribution indexes.

  20. QUANTIFIED COST-BALANCED ROUTING SCHEME FOR OVERLAY MULTICAST

    Institute of Scientific and Technical Information of China (English)

    Lu Jun; Ruan Qiuqi

    2006-01-01

    This paper focuses on the quantitative analysis issue of the routing metrics tradeoff problem, and presents a Quantified Cost-Balanced overlay multicast routing scheme (QCost-Balanced) to the metric tradeoff problem between overlay path delay and access bandwidth at Multicast Server Nodes (MSN) for real-time applications over Internet. Besides implementing a dynamic priority to MSNs by weighing the size of its service clients for better efficiency, QCost-Balanced tradeoffs these two metrics by a unified tradeoff metric based on quantitative analysis. Simulation experiments demonstrate that the scheme achieves a better tradeoff gain in both two metrics, and effective performance in metric quantitative control.

  1. Optimization of multicast optical networks with genetic algorithm

    Science.gov (United States)

    Lv, Bo; Mao, Xiangqiao; Zhang, Feng; Qin, Xi; Lu, Dan; Chen, Ming; Chen, Yong; Cao, Jihong; Jian, Shuisheng

    2007-11-01

    In this letter, aiming to obtain the best multicast performance of optical network in which the video conference information is carried by specified wavelength, we extend the solutions of matrix games with the network coding theory and devise a new method to solve the complex problems of multicast network switching. In addition, an experimental optical network has been testified with best switching strategies by employing the novel numerical solution designed with an effective way of genetic algorithm. The result shows that optimal solutions with genetic algorithm are accordance with the ones with the traditional fictitious play method.

  2. Empirical Evaluation of Superposition Coded Multicasting for Scalable Video

    KAUST Repository

    Chun Pong Lau

    2013-03-01

    In this paper we investigate cross-layer superposition coded multicast (SCM). Previous studies have proven its effectiveness in exploiting better channel capacity and service granularities via both analytical and simulation approaches. However, it has never been practically implemented using a commercial 4G system. This paper demonstrates our prototype in achieving the SCM using a standard 802.16 based testbed for scalable video transmissions. In particular, to implement the superposition coded (SPC) modulation, we take advantage a novel software approach, namely logical SPC (L-SPC), which aims to mimic the physical layer superposition coded modulation. The emulation results show improved throughput comparing with generic multicast method.

  3. Design of an IPTV Multicast System for Internet Backbone Networks

    OpenAIRE

    T. H. Szymanski; Gilbert, D

    2010-01-01

    The design of an IPTV multicast system for the Internet backbone network is presented and explored through extensive simulations. In the proposed system, a resource reservation algorithm such as RSVP, IntServ, or DiffServ is used to reserve resources (i.e., bandwidth and buffer space) in each router in an IP multicast tree. Each router uses an Input-Queued, Output-Queued, or Crosspoint-Queued switch architecture with unity speedup. A recently proposed Recursive Fair Stochastic Matrix Decompos...

  4. Network Coding in a Multicast Switch

    CERN Document Server

    Kim, MinJi; Medard, Muriel; Eryilmaz, Atilla; Koetter, Ralf

    2008-01-01

    The problem of serving multicast flows in a crossbar switch is considered. Intra-flow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is achievable with coding but requires a switch speedup when coding is not allowed. The rate region with coding can be characterized in a simple graph-theoretic manner, in terms of the stable set polytope of the "enhanced conflict graph". No such graph-theoretic characterization is known for the case of fanout splitting without coding. The minimum speedup needed to achieve 100% throughput with coding is shown to be upper bounded by the imperfection ratio of the enhanced conflict graph. When applied to KxN switches with unicasts and broadcasts only, this gives a bound of min{(2K-1)/K,2N/(N+1)} on the speedup. This shows that speedup, which is usually implemented in hardware, can often be substituted by network coding, which can be done in software. Computing an offline schedule (using prior knowled...

  5. CD1c-Expression by Monocytes - Implications for the Use of Commercial CD1c+ Dendritic Cell Isolation Kits.

    Directory of Open Access Journals (Sweden)

    Martine Schrøder

    Full Text Available Conventional dendritic cells (cDCs comprise a heterogeneous population of cells that are important regulators of immunity and homeostasis. CD1c+ cDCs are present in human blood and tissues, and found to efficiently activate naïve CD4+ T cells. While CD1c is thought to specifically identify this subset of human cDCs, we show here that also classical and intermediate monocytes express CD1c. Accordingly, the commercial CD1c (BDCA-1+ Dendritic Cell Isolation Kit isolates two distinct cell populations from blood: CD1c+CD14- cDCs and CD1c+CD14+ monocytes. CD1c+ cDCs and CD1c+ monocytes exhibited strikingly different properties, including their differential regulation of surface marker expression, their levels of cytokine production, and their ability to stimulate naïve CD4+ T cells. These results demonstrate that a commercial CD1c (BDCA-1+ Dendritic Cell Isolation Kit isolates two functionally different cell populations, which has important implications for the interpretation of previously generated data using this kit to characterize CD1c+ cDCs.

  6. Deploying Next Generation Multicast-enabled Applications Label Switched Multicast for MPLS VPNs, VPLS, and Wholesale Ethernet

    CERN Document Server

    Joseph, Vinod

    2011-01-01

    The growth, scale, and prominence of video applications over the years have placed emphasis on the most scalable and efficient way to deliver multi-play content (voice, video and data) to the end user. Multicast is the most effective and efficient carrier of video applications from a network standpoint. Financial organizations deploy large-scale multicast infrastructures to enable trading and e-commerce. The introduction of 4G and beyond makes this technology even more indispensible since mobile operators need an efficient mechanism to deliver repetitive content to many a handset, and multicas

  7. An Optical Multicast Routing with Minimal Network Coding Operations in WDM Networks

    Directory of Open Access Journals (Sweden)

    Huanlin Liu

    2014-01-01

    Full Text Available Network coding can improve the optical multicast routing performance in terms of network throughput, bandwidth utilization, and traffic load balance. But network coding needs high encoding operations costs in all-optical WDM networks due to shortage of optical RAM. In the paper, the network coding operation is defined to evaluate the number of network coding operation cost in the paper. An optical multicast routing algorithm based on minimal number of network coding operations is proposed to improve the multicast capacity. Two heuristic criteria are designed to establish the multicast routing with low network coding cost and high multicast capacity. One is to select one path from the former K shortest paths with the least probability of dropping the multicast maximal capacity. The other is to select the path with lowest potential coding operations with the highest link shared degree among the multiple wavelength disjoint paths cluster from source to each destination. Comparing with the other multicast routing based on network coding, simulation results show that the proposed multicast routing algorithm can effectively reduce the times of network coding operations, can improve the probability of reaching multicast maximal capacity, and can keep the less multicast routing link cost for optical WDM networks.

  8. Research of Mobile Multicast Based on Mobile IP%基于移动IP的移动组播技术研究

    Institute of Scientific and Technical Information of China (English)

    张斌; 张汝云; 邬江兴

    2003-01-01

    This paper discusses the method of mobile multicast based on mobile IP protocol proposed by IETF. At first, the paper analyzes the methods of Remote subscription and Home subscription, points out the latent problem in mobile ip protocol,and gives the methods of mobile multicast and multicast agent to solve mobile multicast problem, then compares delivery cost of multicast and delivery delay of multicast packets as well as disruption of multicast service due to mobility in four kinds of methods of mobile multicast.

  9. Lossless Multicast Handovers in Proxy Fast Mobile IPv6 Networks

    NARCIS (Netherlands)

    Meijerink, Bernd; Heijenk, G.J.

    2015-01-01

    There is a demand in the Public Protection and Disaster Relief (PPDR) community for high bandwidth services on mobile devices. Group communication is an important aspect of PPDR networks. In IP based networks multicast is the preferred method to efficiently transmit data to more than one receiver si

  10. Dynamic multicast routing scheme in WDM optical network

    Science.gov (United States)

    Zhu, Yonghua; Dong, Zhiling; Yao, Hong; Yang, Jianyong; Liu, Yibin

    2007-11-01

    During the information era, the Internet and the service of World Wide Web develop rapidly. Therefore, the wider and wider bandwidth is required with the lower and lower cost. The demand of operation turns out to be diversified. Data, images, videos and other special transmission demands share the challenge and opportunity with the service providers. Simultaneously, the electrical equipment has approached their limit. So the optical communication based on the wavelength division multiplexing (WDM) and the optical cross-connects (OXCs) shows great potentials and brilliant future to build an optical network based on the unique technical advantage and multi-wavelength characteristic. In this paper, we propose a multi-layered graph model with inter-path between layers to solve the problem of multicast routing wavelength assignment (RWA) contemporarily by employing an efficient graph theoretic formulation. And at the same time, an efficient dynamic multicast algorithm named Distributed Message Copying Multicast (DMCM) mechanism is also proposed. The multicast tree with minimum hops can be constructed dynamically according to this proposed scheme.

  11. Using Multicast-SNMP to coordinate Distributed Management Agents

    NARCIS (Netherlands)

    Schönwälder, J.

    1996-01-01

    This paper presents a mechanism that allows one to implement coordination primitives for cooperating management agents based on the Simple Network Management Protocol (SNMP). The multicast extensions presented in this paper allow one to maintain group information of cooperating SNMP agents. We also

  12. WIMAX Basics From PHY Layer to Scheduling And Multicasting Approaches

    Directory of Open Access Journals (Sweden)

    Khaled Elleithy

    2011-02-01

    Full Text Available WiMAX (Worldwide Interoperability for Microwave Access is an emerging broadband wirelesstechnology for providing Last mile solutions for supporting higher bandwidth and multiple serviceclasses with various quality of service requirement. The unique architecture of the WiMAX MAC andPHY layers that uses OFDMA to allocate multiple channels with different modulation schema andmultiple time slots for each channel allows better adaptation of heterogeneous user’s requirements. Themain architecture in WiMAX uses PMP (Point to Multipoint, Mesh mode or the new MMR (Mobile Multihop Mode deployments where scheduling and multicasting have different approaches. In PMP SS(Subscriber Station connects directly to BS (Base Station in a single hop route so channel conditionsadaptations and supporting QoS for classes of services is the key points in scheduling, admission controlor multicasting, while in Mesh networks SS connects to other SS Stations or to the BS in a multi hoproutes, the MMR mode extends the PMP mode in which the SS connects to either a relay station (RS orto Bs. Both MMR and Mesh uses centralized or distributed scheduling with multicasting schemas basedon scheduling trees for routing. In this paper a broad study is conducted About WiMAX technology PMPand Mesh deployments from main physical layers features with differentiation of MAC layer features toscheduling and multicasting approaches in both modes of operations.

  13. Polynomial Time Algorithms for Multicast Network Code Construction

    NARCIS (Netherlands)

    Jaggi, S.; Sanders, P.; Chou, P.A.; Effros, M.; Egner, S.; Jain, K.; Tolhuizen, L.M.G.

    2005-01-01

    The famous max-flow min-cut theorem states that a source node can send information through a network ( ) to a sink node at a rate determined by the min-cut separating and . Recently, it has been shown that this rate can also be achieved for multicasting to several sinks provided that the

  14. Algoritmo de balanceo de carga aplicado a enrutamiento multicast

    Directory of Open Access Journals (Sweden)

    Yezid Donoso Meisel

    2004-01-01

    Full Text Available En este artículo se proponen las bases para la creación del protocolo de enrutamiento multicast con características de ingeniería de tráfico: Pim-Dm/Sm-Te. Este protocolo consistiría en una serie de modificaciones realizadas al protocolo multicast Pim-Dm/ Sm, para permitir que este protocolo realice balanceo de carga y sirva como fuente de información a protocolos de reserva de recursos. Inicialmente se presentan definiciones y conceptos necesarios para la comprensión del funcionamiento del protocolo, tales como enrutamiento multicast en modo denso y enrutamiento multicast en modo esparcido. Se prosigue con la definición y explicación del funcionamiento de Pim-Dm/Sm, seguida de la propuesta y explicación de su funcionamiento. Por último, el lector tendrá acceso a resultados obtenidos a través de la herramienta de simulación, que confirman la utilidad del protocolo

  15. The optimal joint power and rate adaptation for mobile multicast

    DEFF Research Database (Denmark)

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas S.

    2008-01-01

    In this paper we have investigated the joint power and rate adaptation strategies for multicast services for downlink communication. We have proposed a theoretical framework to find out the achievable spectrum efficiency upper boundary of such a scenario and the corresponding optimal solution for...

  16. QoS multicast routing algorithm based on GA

    Institute of Scientific and Technical Information of China (English)

    李腊元; 李春林

    2004-01-01

    The multicast routing problem with multiple QoS constraints in networks with uncertain parameters is discussed, and a network model that is suitable to research such QoS multicast routing problem is described. The QMRGA,a multicast routing policy for Internet, mobile network or other high-performance networks is mainly presented, which is based on the genetic algorithm(GA), and can provide QoS-sensitive paths in a scalable and flexible way in the network environment with uncertain parameters. The QMRGA can also optimize the network resources such as bandwidth and delay, and can converge to the optimal or near-optimal solution within few iterations, even for the network environment with uncertain parameters. The incremental rate of computational cost can be close to a polynomial and is less than exponential rate. The performance measures of the QMRGA are evaluated by using simulations. The results show that QMRGA provides an available approach to QoS multicast routing in network environment with uncertain parameters.

  17. Genetic based optimization for multicast routing algorithm for MANET

    Indian Academy of Sciences (India)

    C Rajan; N Shanthi

    2015-12-01

    Mobile Ad hoc Network (MANET) is established for a limited period, for special extemporaneous services related to mobile applications. This ad hoc network is set up for a limited period, in environments that change with the application. While in Internet the TCP/IP protocol suite supports a wide range of application, in MANETs protocols are tuned to specific customer/application. Multicasting is emerging as a popular communication format where the same packet is sent to multiple nodes in a network. Routing in multicasting involves maintaining routes and finding new node locations in a group and is NP-complete due to the dynamic nature of the network. In this paper, a Hybrid Genetic Based Optimization for Multicast Routing algorithm is proposed. The proposed algorithm uses the best features of Genetic Algorithm (GA) and particle swarm optimization (PSO) to improve the solution. Simulations were conducted by varying number of mobile nodes and results compared with Multicast AODV (MAODV) protocol, PSO based and GA based solution. The proposed optimization improves jitter, end to end delay and Packet Delivery Ratio (PDR) with faster convergence.

  18. Minimum-Energy Wireless Real-Time Multicast by Joint Network Coding and Scheduling Optimization

    Directory of Open Access Journals (Sweden)

    Guoping Tan

    2015-01-01

    Full Text Available For real-time multicast services over wireless multihop networks, to minimize the energy of transmissions with satisfying the requirements of a fixed data rate and high reliabilities, we construct a conflict graph based framework by joint optimizing network coding and scheduling. Then, we propose a primal-dual subgradient optimization algorithm by random sampling K maximal stable sets in a given conflict graph. This method transforms the NP-hard scheduling subproblem into a normal linear programming problem to obtain an approximate solution. The proposed algorithm only needs to adopt centralized technique for solving the linear programming problem while all of the other computations can be distributed. The simulation results show that, comparing with the existing algorithm, this algorithm can not only achieve about 20% performance gain, but also have better performance in terms of convergence and robustness.

  19. Enhancing On-Demand Multicast Routing Protocols using Mobility Prediction in Mobile Ad-hoc Network

    Directory of Open Access Journals (Sweden)

    Nermin Makhlouf

    2014-08-01

    Full Text Available A Mobile Ad hoc Network (MANET is a self-organizing wireless communication network in which mobile devices are based on no infrastructure like base stations or access points. Minimal configuration and quick deployment make ad hoc networks suitable for emergency situations like disaster recovery or military conflict. Since node mobility may cause links to be broken frequently, a very important issue for routing in MANETs is how to set reliable paths which can last as long as possible. To solve this problem, non-random behaviors for the mobility patterns that mobile users exhibit are exploited. This paper introduces a scheme to improve On-Demand Multicast Routing Protocol (ODMRP performances by using mobility prediction. 

  20. Scalable Group Key Management for Secure Multicast: A Taxonomy and New Directions

    Science.gov (United States)

    Zhu, Sencun; Jajodia, Sushil

    Many multicast-based applications (e.g., pay-per-view, online auction, and teleconferencing) require a secure communication model to prevent disclosure of distributed data to unauthorized users. One solution for achieving this goal is to let all members in a group share a key that is used for encrypting data. To provide backward and forward confidentiality [23] (i.e., a new member should not be allowed to decrypt the earlier communication and a revoked user should not be able to decrypt the future communication), this shared group key should be updated and redistributed to all authorized members in a secure, reliable, and timely fashion upon a membership change. This process is referred to as group rekeying.

  1. Distributed QoS multicast routing protocol in ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    Sun Baolin; Li Layuan

    2006-01-01

    Quality of service (QoS) routing and multicasting protocols in ad hoc networks are face with the challenge of delivering data to destinations through multihop routes in the presence of node movements and topology changes. The multicast routing problem with multiple QoS constraints is discussed, which may deal with the delay, bandwidth and cost metrics, and describes a network model for researching the ad hoc networks QoS multicast routing problem. It presents a distributed QoS multicast routing protocol (DQMRP). The proof of correctness and complexity analysis of the DQMRP are also given. Simulation results show that the multicast tree optimized by DQMRP is better than other protocols and is fitter for the network situations with frequently changed status and the real-time multimedia application. It is an available approach to multicast routing decision with ultiple QoS constraints.

  2. Delay-Constrained Multicast Routing Algorithm Based on Average Distance Heuristic

    CERN Document Server

    Ling, Zhou; Yu-xi, Zhu; 10.5121/ijcnc.2010.2212

    2010-01-01

    Multicast is the ability of a communication network to accept a single message from an application and to deliver copies of the message to multiple recipients at different location. With the development of Internet, Multicast is widely applied in all kinds of multimedia real-time application: distributed multimedia systems, collaborative computing, video-conferencing, distance education, etc. In order to construct a delay-constrained multicast routing tree, average distance heuristic (ADH) algorithm is analyzed firstly. Then a delay-constrained algorithm called DCADH (delay-constrained average distance heuristic) is presented. By using ADH a least cost multicast routing tree can be constructed; if the path delay can't meet the delay upper bound, a shortest delay path which is computed by Dijkstra algorithm will be merged into the existing multicast routing tree to meet the delay upper bound. Simulation experiments show that DCADH has a good performance in achieving a low-cost multicast routing tree.

  3. An Approach to Improve the State Scalability of Source Specific Multicast

    Directory of Open Access Journals (Sweden)

    S. A. Al-Talib

    2009-01-01

    Full Text Available Problem statement: Source Specific Multicast (SSM is an acceptable solution for current multicast applications; since the driving applications to date are one to many, including Internet TV, distance learning, file distribution and streaming media. Approach: It was useful for billing, address allocation and security. SSM still had serious state scalability problem when there were a large number of simultaneous on-going multicast groups in the network. Results: In this study, a scheme had been devised to improve the state scalability of source specific multicast. The scheme consisted of two stages: Conclusion/Recommendations: The first stage was to cluster the receivers based on their IP addresses and the second stage was to reduce the multicast state at routers. In order to prove the correctness of the proposed scheme, it had been applied to multicast trees built by other researchers. The results of the comparison approved our statement.

  4. Supporting IP dense mode multicast routing protocols in WDM all-optical networks

    Science.gov (United States)

    Salvador, Marcos R.; Heemstra de Groot, Sonia; Dey, Diptish

    2000-09-01

    Recent developments in all-optical networking and wavelength division multiplexing technologies allow for the support of optical multicasting, a missing feature towards the optical Internet. In this paper we propose a protocol to construct source-rooted WDM multicast trees. The protocol works under dense mode multicasting routing IP protocols and supports network nodes with different degrees of light splitting, wavelength conversion, and add/drop capabilities.

  5. A Dynamic Adaptive Layered Multicast Congestion Control Mechanism

    Institute of Scientific and Technical Information of China (English)

    REN Liyong; LU Xianliang; WEI Qingsong; ZHOU Xu

    2003-01-01

    To solve the problem that most of existing layered multicast protocols cannot adapt to dynamic network conditions because their layers are coarsely granulated and static, a new congestion control mechanism for dynamic adaptive layered multicast(DALM) is presented. In this mechanism, a novel feedback aggregating algorithm is put forward, which can dynamically determine the number of layers and the rate of each layer, and can efficiently improve network bandwidth utilization ratio.Additionally, because all layers is transmitted in only one group, the intricate and time-consuming internet group management protocol(IGMP) operations, caused by receiver joining a new layer or leaving the topmost subscribed layer, are thoroughly eliminated. And this mechanism also avoids other problems resulted from multiple groups. Simulation results show that DALM is adaptive and TCP friendly.

  6. Effective multicasting algorithm for dynamic membership with delay constraint

    Institute of Scientific and Technical Information of China (English)

    CHEN Lin; XU Zheng-quan

    2006-01-01

    This paper proposes an effective heuristic algorithm for dynamic multicast routing with delay-constrained DDMR.The tree constructed by DDMR has the following characteristics: (1) multicast tree changes with the dynamic memberships; (2)the cost of the tree is as small as possible at each node addition/removal event; (3) all of the path delay meet a fixed delay constraint;(4) minimal perturbation to an existing tree. The proposed algorithm is based on "damage" and "usefulness" concepts proposed in previous work, and has a new parameter bf(Balancing Factor) for judging whether or not to rearrange a tree region when membership changes. Mutation operation in Genetic Algorithm (GA) is also employed to find an attached node for a new adding node.Simulation showed that our algorithm performs well and is better than static heuristic algorithms, in term of cost especially.

  7. Fault-Tolerant Tree-Based Multicasting in Mesh Multicomputers

    Institute of Scientific and Technical Information of China (English)

    WU Jie; CHEN Xiao

    2001-01-01

    We propose a fault-tolerant tree-based multicast algorithm for 2-dimensional (2-D) meshes based on the concept of the extended safety level which is a vector associated with each node to capture fault information in the neighborhood. In this approach each destination is reached through a minimum number of hops. In order to minimize the total number of traffic steps, three heuristic strategies are proposed. This approach can be easily implemented by pipelined circuit switching (PCS). A simulation study is conducted to measure the total number of traffic steps under different strategies. Our approach is the first attempt to address the faulttolerant tree-based multicast problem in 2-D meshes based on limited global information with a simple model and succinct information.

  8. Performance and Rekeying Analysis of Multicast Security in LTE

    Directory of Open Access Journals (Sweden)

    Mohsen M. Tantawy

    2013-07-01

    Full Text Available Multimedia Broadcast Multicast Services (MBMS is apoint-to-multipointinterface specification forexisting and upcoming3GPPcellular networks, which is designed to provide efficient delivery ofbroadcastandmulticastservices, within a cellorwithin the core network. Target applications includemobile TVandradio broadcasting, file delivery and emergency alerts.Themain goal of this paper is to assess theperformance of the Secure Multicast Overlay (SMO and the Group Security Association (GSA. Wefunctionally compare GSA with SMO, in terms of Keys management procedures and look up policiesshowing that GSAsolution is appropriate in certain circumstances and SMO solution is appropriate inothers. The comparison will be for different parameters and different services.Also the computational costand storage cost forLogical Key Hierarchy (LKHtreewith and without dynamicrekeying willbecalculated.

  9. Analytical modeling of bargaining solutions for multicast cellular services

    Directory of Open Access Journals (Sweden)

    Giuseppe Araniti

    2013-07-01

    Full Text Available Nowadays, the growing demand for group-oriented services over mobile devices has lead to the definition of new communication standards and multimedia applications in cellular systems. In this article we study the use of game theoretic solutions for these services to model and perform a trade-off analysis between fairness and efficiency in the resources allocation. More precisely, we model bargaining solutions for the multicast data services provisioning and introduce the analytical resolution for the proposed solutions.

  10. Design of an IPTV Multicast System for Internet Backbone Networks

    Directory of Open Access Journals (Sweden)

    T. H. Szymanski

    2010-01-01

    Full Text Available The design of an IPTV multicast system for the Internet backbone network is presented and explored through extensive simulations. In the proposed system, a resource reservation algorithm such as RSVP, IntServ, or DiffServ is used to reserve resources (i.e., bandwidth and buffer space in each router in an IP multicast tree. Each router uses an Input-Queued, Output-Queued, or Crosspoint-Queued switch architecture with unity speedup. A recently proposed Recursive Fair Stochastic Matrix Decomposition algorithm used to compute near-perfect transmission schedules for each IP router. The IPTV traffic is shaped at the sources using Application-Specific Token Bucker Traffic Shapers, to limit the burstiness of incoming network traffic. The IPTV traffic is shaped at the destinations using Application-Specific Playback Queues, to remove residual network jitter and reconstruct the original bursty IPTV video streams at each destination. All IPTV traffic flows are regenerated at the destinations with essentially zero delay jitter and essentially-perfect QoS. The destination nodes deliver the IPTV streams to the ultimate end users using the same IPTV multicast system over a regional Metropolitan Area Network. It is shown that all IPTV traffic is delivered with essentially-perfect end-to-end QoS, with deterministic bounds on the maximum delay and jitter on each video frame. Detailed simulations of an IPTV distribution system, multicasting several hundred high-definition IPTV video streams over several essentially saturated IP backbone networks are presented.

  11. Efficient and secure source authentication scheme for multicast user authentication

    Institute of Scientific and Technical Information of China (English)

    JEONG; Yoon-su; LEE; Sang-hyuk; SHIN; Seung-soo

    2013-01-01

    Multicast technology application has been widely utilized in broadband internet. Source authentication is one of the most needs for many multicast applications transferring real-time information such as stream video and online news. Because multicast current services provided to the group members are changed dynamically, data transferring by a group member is not used by the recipient. In order to verify the identity of the sender who sent the packet and to make sure that the data have not been tampered, an optimized source authentication scheme has been proposed to transfer the authentication information not to the next-door packet. The proposed method for multiple packets authenticates the source with a limited number of electronic signatures. The proposed method can reduce overhead compared to the method by adding a digital signature for every packet. In addition, by sending the generated electronic signature to the first packet and the last packet, it prevents the loss of consecutive packets, as well as a source authentication can be provided in real-time services.

  12. Joint Network Coding for Interfering Wireless Multicast Networks

    CERN Document Server

    Qureshi, Jalaluddin; Cai, Jianfei

    2011-01-01

    Interference in wireless networks is one of the key-capacity limiting factor. The multicast capacity of an ad- hoc wireless network decreases with an increasing number of transmitting and/or receiving nodes within a fixed area. Digital Network Coding (DNC) has been shown to improve the multicast capacity of non-interfering wireless network. However recently proposed Physical-layer Network Coding (PNC) and Analog Network Coding (ANC) has shown that it is possible to decode an unknown packet from the collision of two packet, when one of the colliding packet is known a priori. Taking advantage of such collision decoding scheme, in this paper we propose a Joint Network Coding based Cooperative Retransmission (JNC- CR) scheme, where we show that ANC along with DNC can offer a much higher retransmission gain than that attainable through either ANC, DNC or Automatic Repeat reQuest (ARQ) based retransmission. This scheme can be applied for two wireless multicast groups interfering with each other. Because of the broa...

  13. A Genetic Algorithms Based Approach for Group Multicast Routing

    Directory of Open Access Journals (Sweden)

    Luca Sanna Randaccio

    2006-08-01

    Full Text Available Whereas multicast transmission in one-to-many communications allows the operator to drastically save network resources, it also makes the routing of the traffic flows more complex then in unicast transmissions. A huge amount of possible trees have to be considered and analyzed to find the appropriate routing paths. To address this problem, we propose the use of the genetic algorithms (GA, which considerably reduce the number of solutions to be evaluated. A heuristic procedure is first used to discern a set of possible trees for each multicast session in isolation. Then, the GA are applied to find the appropriate combination of the trees to comply with the bandwidth needs of the group of multicast sessions simultaneously. The goodness of each solution is assessed by means of an expression that weights both network bandwidth allocation and one-way delay. The resulting cost function is guided by few parameters that can be easily tuned during traffic engineering operations; an appropriate setting of these parameters allows the operator to configure the desired balance between network resource utilization and provided quality of service. Simulations have been performed to compare the proposed algorithm with alternative solutions in terms of bandwidth utilization and transmission delay.

  14. Adaptive live multicast video streaming of SVC with UEP FEC

    Science.gov (United States)

    Lev, Avram; Lasry, Amir; Loants, Maoz; Hadar, Ofer

    2014-09-01

    Ideally, video streaming systems should provide the best quality video a user's device can handle without compromising on downloading speed. In this article, an improved video transmission system is presented which dynamically enhances the video quality based on a user's current network state and repairs errors from data lost in the video transmission. The system incorporates three main components: Scalable Video Coding (SVC) with three layers, multicast based on Receiver Layered Multicast (RLM) and an UnEqual Forward Error Correction (FEC) algorithm. The SVC provides an efficient method for providing different levels of video quality, stored as enhancement layers. In the presented system, a proportional-integral-derivative (PID) controller was implemented to dynamically adjust the video quality, adding or subtracting quality layers as appropriate. In addition, an FEC algorithm was added to compensate for data lost in transmission. A two dimensional FEC was used. The FEC algorithm came from the Pro MPEG code of practice #3 release 2. Several bit errors scenarios were tested (step function, cosine wave) with different bandwidth size and error values were simulated. The suggested scheme which includes SVC video encoding with 3 layers over IP Multicast with Unequal FEC algorithm was investigated under different channel conditions, variable bandwidths and different bit error rates. The results indicate improvement of the video quality in terms of PSNR over previous transmission schemes.

  15. Online scene change detection of multicast (MBone) video

    Science.gov (United States)

    Zhou, Wensheng; Shen, Ye; Vellaikal, Asha; Kuo, C.-C. Jay

    1998-10-01

    Many multimedia applications, such as multimedia data management systems and communication systems, require efficient representation of multimedia content. Thus semantic interpretation of video content has been a popular research area. Currently, most content-based video representation involves the segmentation of video based on key frames which are generated using scene change detection techniques as well as camera/object motion. Then, video features can be extracted from key frames. However most of such research performs off-line video processing in which the whole video scope is known as a priori which allows multiple scans of the stored video files during video processing. In comparison, relatively not much research has been done in the area of on-line video processing, which is crucial in video communication applications such as on-line collaboration, news broadcasts and so on. Our research investigates on-line real-time scene change detection of multicast video over the Internet. Our on-line processing system are designed to meet the requirements of real-time video multicasting over the Internet and to utilize the successful video parsing techniques available today. The proposed algorithms extract key frames from video bitstreams sent through the MBone network, and the extracted key frames are multicasted as annotations or metadata over a separate channel to assist in content filtering such as those anticipated to be in use by on-line filtering proxies in the Internet. The performance of the proposed algorithms are demonstrated and discussed in this paper.

  16. Design, Implementation, and Performance Evaluation of Efficient PMIPv6 Based Mobile Multicast Sender Support Schemes

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2015-01-01

    Full Text Available Proxy Mobile IPv6 (PMIPv6 is proposed as a promising network-based mobility management protocol, which does not need any participation of mobile nodes. PMIPv6 does not support the multicast well and most of the current research concentrates on the mobile multicast receiver. However, the mobile multicast sender is also very important and challenging, which has not been addressed well. Therefore, in this paper we propose two efficient PMIPv6 based mobile multicast sender support schemes which are PMIP bidirectional tunneling (PMIP-BT and PMIP direct routing (PMIP-DR. In the PMIP-BT, the multicast traffic can be delivered through the PMIPv6 bidirectional tunnel, while, in the PMIP-DR, the multicast data can be transmitted via an optimized direct multicast routing. Both of them can support the multicast sender mobility transparently enabled in the PMIPv6 networks. We evaluate the performance of the proposed schemes by theoretical analysis, and the numerical results show that the proposed schemes have a better performance in terms of the signaling cost than the current schemes. Meanwhile, the proposed schemes are also implemented on the test bed, and the experimental results not only verify the validity and feasibility of our proposed schemes, but also conclude the different scenarios to which they are applicable.

  17. A Source-Based Multicast Scheme in IEEE 802.16 Mesh Mode

    Directory of Open Access Journals (Sweden)

    Ali Azarpeyvand

    2012-12-01

    Full Text Available WiMAX based on IEEE 802.16 is known as one of effective technologies for transmission of multimedia to groups of receivers. There are two operational modes in WiMAX: point to multi point (PMP for single hop transmission and a mesh node for multi-hop transmission. The current standard only defines unicast transmission under mesh mode thus the performance is deteriorated for multimedia applications with multicast nature. In this paper, we first propose a mechanism for source-based tree topology construction aiming at facilitating multicast transmission in WiMAX mesh network. In the proposed approach, the multicast tree is constructed considering available link’s bandwidth and multicast group members. After constructing the multicast tree we propose a novel scheduling algorithm to improve the transmission throughout. In the proposed scheduling algorithm a parent node uses broadcasting when the number of its children belonging to a multicast group excesses a threshold. Extensive simulation results show that the proposed multicast mechanism improves multicast transmission efficiency and reduces scheduling time slots noticeably in comparison to the approach mandated by the IEEE 802.16 standard.

  18. Almost optimal distributed M2M multicasting in wireless mesh networks

    DEFF Research Database (Denmark)

    Xin, Qin; Manne, Fredrik; Zhang, Yan

    2012-01-01

    nodes. It is known that the computation of an optimal M2M multicasting schedule isNP-hard. We present a fully distributed deterministic algorithm for such an M2M multicasting problem and analyze its time complexity. We show that if the maximum hop distance between any two out of the k participants is d...

  19. A Hybrid Reliable Data Transmission based on Ant-agent Resource Allocation Technique in EEMCC Protocol for MANETS

    Directory of Open Access Journals (Sweden)

    Dr. M. Rajanbabu

    2014-04-01

    Full Text Available Real time multicast applications in mobile adhoc network brings forward added advantages in wireless network. The fragile and mobile environment of adhoc network produces the need of bandwidth allocation for real time applications. Reliability is also an important factor in multicasting in mobile adhoc networks (MANETs, as it confirms eventual delivery of all the data to all the group members, without enforcing any particular delivery order in EEMCCP. In the first phase of this paper, we design an "ant agent-resource allocation‟ technique for reserving bandwidth for real-time multicast applications. In the forward phase, the source sends a forward ant agent which collects the bandwidth information of intermediate nodes and reserves a bandwidth for real-time flow for each multicast receiver. In the backward phase, the backward ant confirms the allocation and feeds the bandwidth information to the source.

  20. Reliable Multicast Protocol Based on Reliable Active Node%用ANTS模拟实现RANRM协议

    Institute of Scientific and Technical Information of China (English)

    蔡洪斌; 周明天; 杨国纬

    2002-01-01

    Internet的端到端可靠性技术,使多播通信遇到了很多问题.该文提出了基于可靠主动结点的可靠多播通信(RANRM)协议,它能有效地解决多播通信的可靠性和可伸缩性问题,并且能兼顾可靠性和传输效率.理论分析表明:该协议占用带宽少.该文重点设计了模拟程序,用ANTS进行了模拟实验,实验结果与理论分析一致.

  1. Wavelength conversion, time demultiplexing and multicasting based on cross-phase modulation and four-wave mixing in dispersion-flattened highly nonlinear photonic crystal fiber

    Science.gov (United States)

    Hui, Zhan-Qiang; Zhang, Jian-Guo

    2012-05-01

    We propose the use of cross-phase modulation (XPM) and four-wave mixing (FWM) in dispersion-flattened highly nonlinear photonic crystal fibers (HNL-PCFs) to implement the functionalities of wavelength conversion, simultaneous time demultiplexing and wavelength multicasting in optical time-division multiplexing (OTDM) systems. The experiments on wavelength conversion at 80 Gbit s-1and OTDM demultiplexing from 80 to 10 Gbit s-1 with wavelength multicasting of two channels are successfully demonstrated to validate the proposed scheme, which are carried out by using two segments of dispersion-flattened HNL-PCFs with lengths of 100 and 50 m, respectively. Moreover, the bit error rate (BER) performance is also measured. The results show that our designed system can achieve a power penalty of less than 4.6 dB for two multicasting channels with a 24 nm wavelength span at the BER of 10-9 when compared with the 10 Gbit/s back-to-back measurement. The proposed system is transparent to bit rate since only an ultrafast third-order nonlinear effect is used. The resulting configuration is compact, robust and reliable, benefiting from the use of dispersion-flattened HNL-PCFs with short lengths. This also makes the proposed system more flexible in the operational wavelengths than those based on dispersion-shifted fibers and traditional highly nonlinear fibers. The work was supported in part by the CAS/SAFEA International Partnership Program for Creative Research Teams.

  2. On Multi-constrained Application Layer Multicast Algorithm%多约束的应用层组播算法研究

    Institute of Scientific and Technical Information of China (English)

    韩广; 刘海林

    2015-01-01

    组播在分布交互式应用、网络在线游戏、流媒体等方面具有广泛的应用.为满足应用层组播QoS要求,在文构建多约束应用层组播树模型,基于遗传算法、采用双染色编码方式寻找最优生成树.该算法既能满足实时性、节点负载限制,又能最小化组网资源消耗,高效利用网络资源.实验表明,该算法收敛速度快,可靠性高.%Multicast has wide applications in distributed interactive applications,online games,streaming media and etc.To meet the application layer multicast QoS requirement,this paper builds a multi-con-strained application layer multicast tree model and tries to find the optimal spanning tree based on genetic algorithm and dichromatic coding.The algorithm can meet the real-time requirement and node load limit as well as minimize network resource consumption and take full advantage of network resources.It turns out to be featured by fast convergence and high reliability.

  3. Fair Resource Allocation in Networks with Coexisting Unicast and Multirate Multicast Flows

    Institute of Scientific and Technical Information of China (English)

    Dong Qian(董谦); Xie Jianying; Liu Fengqing; Zhu Xu

    2004-01-01

    To maximize the aggregate user utility in networks with both multirate multicast and unicast traffic, a unified convex program formulation of the problem is used to integrate multicast and unicast sessions into a common framework, which also takes into account the heterogeneity of multicast receivers. By applying a penalty function approach, a heuristic rate control algorithm is derived. In the distributed implementation of the algorithm in IP networks, core routers employ Random Early Detection (RED) to mark packets in the case of congestion; end-users analyze congestion feedback information and update their rates to calculated optimal values. With an appropriate choice of utility functions and parameters, multicast and unicast sessions can share network resources in the proportional fair manner. Simulation results prove the algorithm's effectiveness. Study is also done on the effect of bandwidth discretization density upon resource allocation fairness in a layered multicast scenario.

  4. Scalable Base-Station Model-Based Multicast in Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    Shao-Liang Peng; Shan-Shan Li; Lei Chen; Yu-Xing Peng; Nong Xiao

    2008-01-01

    Multicast is essential for wireless sensor network (WSN) applications. Existing multicast protocols in WSNs are often designed in a P2P pattern, assuming small number of destination nodes and frequent changes in network topologies.In order to truly adopt multicast in WSNs, we propose a base-station model-based multicast, SenCast, to meet the general requirements of applications. SenCast is scalable and energy-efficient for large group communications in WSNs. Theoretical analysis shows that SenCast is able to approximate the Minimum Nonleaf Nodes (MNN) problem to a ratio of In |R| (R is the set of all destinations), the best known lowest bound. We evaluate our design through comprehensive simulations and prototype implementations on Mica2 motes. Experimental results demonstrate that SenCast outperforms previous multicast protocols including the most recent work uCast.

  5. Multiple constraints QoS multicast routing optimization algorithm in MANET based on GA

    Institute of Scientific and Technical Information of China (English)

    Baolin Sun; Shangchao Pi; Chao Gui; Yue Zeng; Bing Yan; Wenxiang Wang; Qianqing Qin

    2008-01-01

    Usually multiple quality of service (QoS) guarantees are required in most multicast applications. This paper presents a multiple constraints algorithm for multicast traffic engineering in mobile ad hoc networks (MANET). The proposed algorithm is a new version of multiple constraints QoS multicast routing optimization algorithm in MANET based on genetic algorithm (MQMGA). The proposed MQMGA can optimize the maximum link utilization, the cost of the multicast tree, the selection of the long-life path, the average delay and the maximum end-to-end delay. Experimental result shows that the approach is efficient, has promising performance in multicast traffic engineering and for evaluating the route stability in dynamic mobile networks.

  6. Simultaneous multichannel wavelength multicasting and XOR logic gate multicasting for three DPSK signals based on four-wave mixing in quantum-dot semiconductor optical amplifier.

    Science.gov (United States)

    Qin, Jun; Lu, Guo-Wei; Sakamoto, Takahide; Akahane, Kouichi; Yamamoto, Naokatsu; Wang, Danshi; Wang, Cheng; Wang, Hongxiang; Zhang, Min; Kawanishi, Tetsuya; Ji, Yuefeng

    2014-12-01

    In this paper, we experimentally demonstrate simultaneous multichannel wavelength multicasting (MWM) and exclusive-OR logic gate multicasting (XOR-LGM) for three 10Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signals in quantum-dot semiconductor optical amplifier (QD-SOA) by exploiting the four-wave mixing (FWM) process. No additional pump is needed in the scheme. Through the interaction of the input three 10Gbps DPSK signal lights in QD-SOA, each channel is successfully multicasted to three wavelengths (1-to-3 for each), totally 3-to-9 MWM, and at the same time, three-output XOR-LGM is obtained at three different wavelengths. All the new generated channels are with a power penalty less than 1.2dB at a BER of 10(-9). Degenerate and non-degenerate FWM components are fully used in the experiment for data and logic multicasting.

  7. Duty-Cycle-Aware Minimum Energy Multicasting of Passive RFID Wake-up Radios for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    M. Pavan Kumar Reddy

    2014-04-01

    Full Text Available In duty-cycled wireless sensor networks, the nodes switch between active and dormant states, and each node determine its active/dormant schedule independently. This complicates the Minimum Energy Multicasting (MEM problem in wireless sensor networks both for one-to-many multicasting and for all-to-all multicasting. In the case of one-to-many multicasting, we present a formalization of the Minimum-Energy Multicasting Tree Construction and Scheduling (MEMTCS problem. We prove that MEMTCS problem is NP-hard and propose a polynomial-time approximation algorithm for the MEMTCS problem. In the case of all-to-all multicasting, we prove that the Minimum-Energy Multicast Backbone Construction and Scheduling (MEMBCS problem is also NP-hard and present an approximation algorithm for it. Compared to duty cycling, wake-up radios save more energy by reducing unnecessary wake-ups and collisions.

  8. CD1 mediated T cell recognition of glycolipids.

    Science.gov (United States)

    Zajonc, Dirk M; Kronenberg, Mitchell

    2007-10-01

    Specialized subsets of T lymphocytes can distinguish the carbohydrate portions of microbial and self-glycolipids when they are presented by proteins in the CD1 family of antigen presenting molecules. Recent immunochemical and structural analyses indicate that the chemical composition of the presented carbohydrate, together with its precise orientation above the CD1 binding groove, determines if a particular T cell is activated. More recently, however, it has been shown that the lipid backbone of the glycolipid, buried inside the CD1 protein, also can have an impact on T cell activation. While glycolipid recognition is a relatively new category of T cell specificity, the powerful combination of microbial antigen discovery and structural biochemistry has provided great insight into the mechanism of carbohydrate recognition.

  9. Minimum Interference Channel Assignment Algorithm for Multicast in a Wireless Mesh Network.

    Science.gov (United States)

    Choi, Sangil; Park, Jong Hyuk

    2016-12-02

    Wireless mesh networks (WMNs) have been considered as one of the key technologies for the configuration of wireless machines since they emerged. In a WMN, wireless routers provide multi-hop wireless connectivity between hosts in the network and also allow them to access the Internet via gateway devices. Wireless routers are typically equipped with multiple radios operating on different channels to increase network throughput. Multicast is a form of communication that delivers data from a source to a set of destinations simultaneously. It is used in a number of applications, such as distributed games, distance education, and video conferencing. In this study, we address a channel assignment problem for multicast in multi-radio multi-channel WMNs. In a multi-radio multi-channel WMN, two nearby nodes will interfere with each other and cause a throughput decrease when they transmit on the same channel. Thus, an important goal for multicast channel assignment is to reduce the interference among networked devices. We have developed a minimum interference channel assignment (MICA) algorithm for multicast that accurately models the interference relationship between pairs of multicast tree nodes using the concept of the interference factor and assigns channels to tree nodes to minimize interference within the multicast tree. Simulation results show that MICA achieves higher throughput and lower end-to-end packet delay compared with an existing channel assignment algorithm named multi-channel multicast (MCM). In addition, MICA achieves much lower throughput variation among the destination nodes than MCM.

  10. A Novel Approach to Overlay Multicasting Schemes for Multi-Hop Ad-Hoc Networks

    Science.gov (United States)

    Kang, Namhi; Oh, Jejun; Kim, Younghan

    Multicast is an efficient transport mechanism for group-based community communications and mobile ad-hoc networks (MANET) is recently regarded as a promising solution for supporting ubiquitous computing as an underlying network technology. However, it is challenging to deploy the multicast mechanism used in a wired network directly into MANET owing to scarce resources in wireless networks and unpredictable changes in network topology. Several multicast mechanisms have been proposed in the literature to overcome these limitations. In MANET, especially, overlay multicasting schemes present several advantages over network-based multicasting schemes. However we have observed a common limitation of previously proposed overlay multicasting schemes. They introduce redundant data transmissions that waste network bandwidth and the battery of relay nodes. The observation motivated us to propose an efficient way to create and maintain a “semi-overlay structure” that utilizes a few nonmember nodes selected as branch nodes. The proposed scheme, called “SOMRP (Semi-overlay multicast routing protocol),” has been evaluated by using extensive network simulation in two different scenarios, comparing the performance of SOMRP with two previously proposed schemes. Simulation results show that SOMRP outperforms the two schemes in terms of the packet delivery ratio, transmission cost and end-to-end delay.

  11. QoS-aware multicast routing protocol for Ad hoc networks

    Institute of Scientific and Technical Information of China (English)

    Sun Baolin; Li Layuan

    2006-01-01

    Ad hoc wireless networks consist of mobile nodes interconnected by multihop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. Due to bandwidth constraint and dynamic topology of mobile ad hoc networks, supporting Quality of Service (QoS) is an inherently complex, difficult issue and very important research issue. MAODV (Multicast Ad hoc Ondemand Distance Vector) routing protocol provides fast and efficient route establishment between mobile nodes that need to communicate with each other. MAODV has minimal control overhead and route acquisition latency. In addition to unicast routing, MAODV supports multicast and broadcast as well.The multicast routing problem with multiple QoS constraints, which may deal with the delay, bandwidth and packet loss measurements is discussed, and a network model for researching the ad hoc network QoS multicast routing problem is described. It presents a complete solution for QoS multicast routing based on an extension of the MAODV routing protocol that deals with delay, bandwidth and packet loss measurements. The solution is based on lower layer specifics. Simulation results show that, with the proposed QoS multicast routing protocol, end-to-end delay, bandwidth and packet loss on a route can be improved in most of cases. It is an available approach to multicast routing decision with multiple QoS constraints.

  12. A Supporting Efficient and Dynamic Multicasting Over Multiple Regions in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    S.Firthouse

    2012-02-01

    Full Text Available Designing multicast routing protocol is a big challenge due to difficulty in achieving group membership management, packet forwarding and maintenance of multicast structure over the dynamic network topology. In this paper, we proposed a novel Efficient Geographic Multicast Protocol (EGMP. A network wide zone-based bi-directional tree is used to achieve efficient membership management and multicast delivery. In Efficient EGMP an efficient distributed algorithm is used, that support dynamic changes to the multicast group during tree building and allows overlapping join/leave operations. The multicast tree is constructed based on zone depth, which is efficient in guiding tree branch building and tree structure maintenance. Nodes in the network self-organized into zones and zone-based bidirectional-tree-based distribution paths are built. Our simulation results demonstrate that EGMP has high packet delivery ratio, low control overhead and multicast group joining delay under all test scenarios, and is scalable to both group size and network size.

  13. Polymorphism in Exon 2 of CD1 Genes in Southwest of Iran

    Directory of Open Access Journals (Sweden)

    Hossein Golmoghaddam

    2013-07-01

    Full Text Available Background: The CD1 family is less variable transmembrane antigen presenting molecules related to the MHC molecules. CD1a and CD1e genes are the most polymorphic ones associated with autoimmune diseases. The aim was to better clarify the map of CD1 genes in Southwest Iranian normal population for implications in vaccine design.Methods: In this study we investigated the polymorphism of CD1a, CD1d and CD1e in 311 healthy individuals from Fars Province in Southwest of Iran by PCR-SSP method.Results: Six of individuals had homozygote CD1a 01/01 genotype and 248 had homozygote CD1a 02/02 genotype. CD1d was found to be monomorphic with all tested individuals showing CD1d 01/01 genotype. Hundred and eleven individuals had homozygote CD1e 01/01 genotype and 48 had homozygote CD1e 02/02 genotype. The frequencies of CD1a 01 and CD1a 02 alleles were 11% and 89% while the frequencies of CD1e 01 and CD1e 02 alleles were 60.1% and 39.9%, respectively. Consistent with previous reports on other genes, a high degree of similarity in CD1a and CD1e allelic distribution was observed between Southwest Iranians and other Indo-European populations. However, the allelic frequency of the CD1a and CD1e alleles showed a significant difference from those of Chinese Han and She populations.Conclusion: These data are notable in the light of relatively recent genetic admixture along the Silk Road. Considering the significance of CD1 alleles in some autoimmune and infectious diseases and with the admixed nature of Iranian population, mapping the distribution of CD1e alleles in different regions of Iran can be useful in future designing of preventive and therapeutic vaccines.

  14. An Intelligent Multicast Ad-hoc On demand Distance Vector Protocol for MANETs

    Directory of Open Access Journals (Sweden)

    E. Baburaj

    2008-06-01

    Full Text Available Recently multicast ro uting protocols in Mobile Ad-hoc Networks (MANETs are emerging for wireless group communication. This includes application such as multipoint data dissemination and multiparty conferencing which made the analytical design and development of the MANETs in a very efficient manner. For MANETs there are several multicast routing protocols are available, but they perform well under specific scenarios only. The topology of a MANET changes adequately based on the random mobility of network nodes, unlike the network topology of a wired network which is static.Multicast routing protocol outperforms the basic broadcast routing by sharing the resources along general links, while sending information to a set of predefined multiple destinations in a concurrent way. Due to the lack of redundancy in multipath and multicast structures, the multicast routing protocols are vulnerable to the component failure in ad-hoc networks. So it is the dire need to solve the problem optimally. One of the efficient techniques for solving the optimization problem is the Genetic Algorithm (GA. The key factors that determine the performance of GA is by the well designed architecture of chromosomes and operators in the intelligent algorithm. This paper proposes a new genetic algorithm based Multicast Ad-hoc On demand Distance Vector Protocol for MANETs (GA-MAODV, which improves the packet delivery ratio of the routing messages. The GAbased MAODV allows each node in the network to send out multicast data packets, and the multicast data packets are broadcast when propagating along the multicast group tree.

  15. Ruteo multicast mediante algoritmos genéticos

    OpenAIRE

    Klenzi, Raúl O.; Sánchez Tores, Héctor A.; Ortega, Manuel Oscar; Naranjo, Viviana; Espósito, Gabriela

    2000-01-01

    Los sistemas o redes de comunicación construidos teniendo en cuenta el modelo de referencia OSI (Open Systems lnterconection) o la arquitectura de Internet, fueron diseñados para soportar servicios o comunicaciones punto a punto, donde la información fluye entre dos usuarios únicamente. Uno de los tópicos en el cual las redes de computadoras actuales están poniendo mucho énfasis, proviene de las aplicaciones multicast o de grupo. Estas involucran más de dos usuarios (estos usuarios definen...

  16. IP MULTICAST GROUP MANAGEMENT FOR BROADCAST LANS DISTRIBUTION

    Institute of Scientific and Technical Information of China (English)

    阿姆贾德

    2001-01-01

    Problems of the current IGMP mechanism were identified, such as unnecessary periodic probing of hosts and leave latency, which wastes bandwidth and cause more traffic and overhead. Alternative mechanism that preserve the IP multicast model but employ join/leave messages to track local group membership for broadcast LANs (shared medium LANs) was proposed in this paper. We describe the implementation requirements of the new mechanism and compare it to existing one, demonstrating that join/leave approach is uniformly superior for the environment of broadcast LANs.

  17. Blocking Analysis of Time-Division Multiplexed Multicast Switch

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The particular switch concerned here is a Three-Stage Time-space-time (TST) interconnection network and performs the time-division circuit switching. The input and output stages are Time Slot Interchangers (TSI). The central stage is a time-multiplexed switch with two ports per address. By exploiting the channel grouping at the central stage as well as reducing the average loading at each internal frame,the three-stage multicast switch has potential to remove almost all slot contention blockings.

  18. Distributed multicast routing algorithm with dynamic performance in multimedia networks

    Institute of Scientific and Technical Information of China (English)

    Zhu Baoping; Zhang Kun

    2009-01-01

    Tbe delay and DVBMT problem is known to be NP-complete. In this paper, an efficient distributed dynamic multicast muting algorithm was proposed to produce muting trees with delay and delay variation constraints. The pro-posed algorithm is fully distributed, and supports the dynamic reorganizing of the muhicast tree in response to changes for the destination. Simulations demonstrate that our algorithm is better in terms of tree delay and muting success ratio as compared with other existing algorithms, and performs excellently in delay variation performance under lower time complexity, which ensures it to support the requirements of real-time multimedia communications more effectively.

  19. Distributed QoS-aware source-specific multicast routing protocol

    Institute of Scientific and Technical Information of China (English)

    WANG Jing; LIU Wei-ning; SONG Wei

    2005-01-01

    A distributed QoS (quality of service) -aware source-specific multicast routing protocol--DQSSMR is proposed to increase the successful join ratio and lower the overhead of the control message in QoS required multicast routing. By an improved searching strategy, the cost of message control is reduced and the successful join ratio is increased. The network load is balanced due to the distributed routing operation and the scalability is enhanced further because of the usage of SSM (source-specific multicast) service model in DQSSMR. The analysis results indicate that DQSSMR performs as expected.

  20. Dynamic Load Balancing Based on Restricted Multicast Tree in Homogeneous Multiprocessor Systems

    Institute of Scientific and Technical Information of China (English)

    LIU Bin; SHI Feng; GAO Yu-jin

    2008-01-01

    To decrease the cost of exchanging load information among processors, a dynamic load-balancing (DLB) algorithm which adopts multicast tree technology is proposed. The multicast tree construction rules are also proposed to avoid wrongly transferred or redundant DLB messages due to the overlapping of multicast trees. The proposed DLB algorithm is distributed controlled, sender initiated and can help heavily loaded processors with complete distribution of redundant loads with minimum number of executions. Experiments were executed to compare the effects of the proposed DLB algorithm and other three ones, the results prove the effectivity and practicability of the proposed algorithm in dealing with great scale compute-intensive tasks.

  1. Integration of look-ahead multicast and unicast scheduling for input-queued cell switches

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2012-01-01

    -ofline (HOL) blocking problem that the weight-based algorithm (WBA) suffers from. Leveraging the FILter & Merge (FILM) scheme, multicast and unicast traffic are independently scheduled based on their requests. Decisions are integrated following a specific policy. Remainder is looped back to the filtering...... module that filters out the conflicting requests to ensure fairness. Simulation results show that comparing with the scheme using WBA for the multicast scheduling, the scheme proposed in this paper reduces the HOL blocking problem for multicast traffic and provides a significant improvement in terms...

  2. Uso extendido de árboles de distribución multicast por emisor

    OpenAIRE

    Rigotti, Guillermo

    2001-01-01

    Algunas clases de aplicaciones multicast, como RTP y multicast confiable consisten de un emisor y un conjunto de receptores que envían información de feedback a dicho emisor y al conjunto de receptores. Si el soporte multicast provisto está basado en árboles de distribución por emisor, dicha característica puede causar un overhead excesivo, especialmente en los casos en que el número de receptores crece (en el orden de miles de receptores). La razón de tal overhead es la necesidad de crear...

  3. Layered Multicast Encryption of Motion JPEG2000 Code Streams for Flexible Access Control

    Science.gov (United States)

    Nakachi, Takayuki; Toyoshima, Kan; Tonomura, Yoshihide; Fujii, Tatsuya

    In this paper, we propose a layered multicast encryption scheme that provides flexible access control to motion JPEG2000 code streams. JPEG2000 generates layered code streams and offers flexible scalability in characteristics such as resolution and SNR. The layered multicast encryption proposal allows a sender to multicast the encrypted JPEG2000 code streams such that only designated groups of users can decrypt the layered code streams. While keeping the layering functionality, the proposed method offers useful properties such as 1) video quality control using only one private key, 2) guaranteed security, and 3) low computational complexity comparable to conventional non-layered encryption. Simulation results show the usefulness of the proposed method.

  4. Realization of IPv6 Multicast Interworking between MANET and Fixed Networks

    Institute of Scientific and Technical Information of China (English)

    WANG Liang-you

    2003-01-01

    Nowadays, more and more attention is paid to the Mobile Ad hoc Network (MANET) because of its flexibility. To provide Internet access for MANET, the interworking mechanism between MANET and IP based fixed network is needed, which has become a vivid research area. However, so far, little work has been done to connect the multicast protocols on both sides so that users can access multicast services on either side. In this paper, a so-called Modified MLD (M.MLD) is proposed as a solution to IPv6 multicast interworking between MANET and fixed networks.

  5. QoS Multicast Routing Based on Ant Algorithm in Internet

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, based on ant-algorithm, we propose a QoS multicast routing scheme in Internet. We first describe ant-algorithm model and give ant-network model, then present an approach using ant-algorithm to optimize the multicast routes with QoS constaints. Finally, simulations has been made to show the efficiency of the approach in the environment of OPNET simulation software, and the simulation results show that the proposed approach can find the best optimal multicast routes which can satisfy the delay-bounded requirement and avoid congested nodes as soon as possible.

  6. Dynamic Multicast Grouping Approach in HLA-Based Distributed Interactive Simulation

    Institute of Scientific and Technical Information of China (English)

    DAI Zhong-jian; HOU Chao-zhen

    2005-01-01

    In order to improve the efficiency of data distributed management service in distributed interactive simulation based on high level architecture (HLA) and to reduce the network traffic and save the system resource, the approaches of multicast grouping in HLA-based distributed interactive simulation are discussed. Then a new dynamic multicast grouping approach is proposed. This approach is based on the current publication and subscription region in the process of simulation. The results of simulation experiment show that this approach can significantly reduce the message overhead and use fewer multicast groups.

  7. Core Placement Algorithm for Multicast Routing with QoS Requirements

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Differing from the source-oriented algorithms, the Core-Based Tree (CBT) multicast routing architecture establishes a single shared tree for multiple connections on a multicast group, which results in higher ratio of network resources utilization. In alluding to the problem of Core Placement, we propose a simple method (QOCP) to locate an optimal core node, which can minimize the multicast delay and inter-destination delay variation simultaneously. The simulation results show that our method is very effective, and outperforms the other algorithms studied in this paper.

  8. Explicit Rate Adjustment (ERA: Responsiveness, Network Utilization Efficiency and Fairness for Layered Multicast

    Directory of Open Access Journals (Sweden)

    Somnuk PUANGPRONPITAG

    2005-08-01

    Full Text Available To provide layered multicast with responsiveness, efficiency in network utilization, scalability and fairness (including inter-protocol fairness, intra-protocol fairness, intra-session fairness and TCP-friendliness for layered multicast, we propose in this paper a new multicast congestion control, called Explicit Rate Adjustment (ERA. Our protocol uses an algorithm relying on TCP throughput equation and Packet-bunch Probe techniques to detect optimal bandwidth utilization; then adjusts the reception rate accordingly. We have built ERA into a network simulator (ns2 and demonstrate via simulations that the goals are reached.

  9. Multicast Congestion Control Based on Multi Token Barrels%基于多令牌桶的组播拥塞控制

    Institute of Scientific and Technical Information of China (English)

    高永辉; 蒋林

    2012-01-01

    IP multicast is an effective data transmission, over the past few years, the multicast transmission mechanism has become an active area of research. However, it is very difficult to realise reliability and to achieve in multicast congestion because of its characteristics, multicast congestion control issues have not been able to get a good solution, it has become a bottleneck in its development. The increasing deterioration of the UDP data stream aggravates the ability of TCP congestion control, and it is one of the reasons to cause high packet loss rate. It presents a way to assign a fixed IP on the LAN bandwidth expansion token bucket algorithm, extends the number of token bucket, a token bucket control of an IP, eliminating the shortcomings of shared bandwidth, and through the design of circuits, modeling and simulation results show it can control the access of multicast and ensure the Qos of network and the design of the circuit occupies less hardware resources, which can be used in high speed circuits.%IP组播是一种有效的数据传输方式,在过去几年中,组播传输机制已经成为一个活跃的研究领域.但由于其自身特性决定了在组播中实现可靠性和拥塞控制非常困难,组播的拥塞控制问题一直没能得到很好的解决,这成为了其发展的瓶颈,不断增加的UDP数据流恶化了TCP控制拥塞的能力,而且是引起高丢包率的原因之一.文中提出了一种可以对局域网内IP分配固定带宽的扩展令牌桶算法,扩展了令牌桶个数,一个令牌桶控制一个IP,消除了共享带宽的缺点,并通过设计电路,建模仿真结果表明可以对路由器交换节点的组播达到准入控制,防止造成网络拥塞,最大限度保证网络Qos,并且设计的电路占用硬件资源少,能够应用于高速电路当中.

  10. Capacity of a Class of Multicast Tree Networks

    CERN Document Server

    Lee, Si-Hyeon

    2010-01-01

    In this paper, a class of single-source multicast discrete memoryless relay networks having a tree topology is considered in which the root node is the source, each parent node in the graph has at most one noisy child node and any number of noiseless child nodes, and subsets of leaf nodes are destinations. For this class of multicast tree networks, lower and upper bounds on the capacity are presented and these two bounds are shown to meet when each set of nodes forming a destination is included in a disjoint subtree, which includes the single-destination case. For achievablity, a coding scheme is constructed where each noisy relay employs a combination of decode-and-forward (DF) and compress-and-forward (CF) and each noiseless relay performs random binning. In our coding scheme, codebook constructions and relay operations are independent for each node and do not depend on the network topology, which is a key ingredient of our achievability proof. We note that our result is the first to show that the combinati...

  11. Game and Balance Multicast Architecture Algorithms for Sensor Grid

    Science.gov (United States)

    Fan, Qingfeng; Wu, Qiongli; Magoulés, Frèdèric; Xiong, Naixue; Vasilakos, Athanasios V.; He, Yanxiang

    2009-01-01

    We propose a scheme to attain shorter multicast delay and higher efficiency in the data transfer of sensor grid. Our scheme, in one cluster, seeks the central node, calculates the space and the data weight vectors. Then we try to find a new vector composed by linear combination of the two old ones. We use the equal correlation coefficient between the new and old vectors to find the point of game and balance of the space and data factorsbuild a binary simple equation, seek linear parameters, and generate a least weight path tree. We handled the issue from a quantitative way instead of a qualitative way. Based on this idea, we considered the scheme from both the space and data factor, then we built the mathematic model, set up game and balance relationship and finally resolved the linear indexes, according to which we improved the transmission efficiency of sensor grid. Extended simulation results indicate that our scheme attains less average multicast delay and number of links used compared with other well-known existing schemes. PMID:22399992

  12. Abacus switch: a new scalable multicast ATM switch

    Science.gov (United States)

    Chao, H. Jonathan; Park, Jin-Soo; Choe, Byeong-Seog

    1995-10-01

    This paper describes a new architecture for a scalable multicast ATM switch from a few tens to thousands of input ports. The switch, called Abacus switch, has a nonblocking memoryless switch fabric followed by small switch modules at the output ports; the switch has input and output buffers. Cell replication, cell routing, output contention resolution, and cell addressing are all performed distributedly in the Abacus switch so that it can be scaled up to thousnads input and output ports. A novel algorithm has been proposed to resolve output port contention while achieving input and output ports. A novel algorithm has been proposed to reolve output port contention while achieving input buffers sharing, fairness among the input ports, and multicast call splitting. The channel grouping concept is also adopted in the switch to reduce the hardware complexity and improve the switch's throughput. The Abacus switch has a regular structure and thus has the advantages of: 1) easy expansion, 2) relaxed synchronization for data and clock signals, and 3) building the switch fabric using existing CMOS technology.

  13. Optimización multiobjetivo para enrutamiento multicast en overlay networks utilizando algoritmos evolutivos Multiobjective Optimization for Multicast Routing in Overlay Networks using Evolutionary Algorithms

    Directory of Open Access Journals (Sweden)

    Juan Carlos Montoya M.

    2008-06-01

    Full Text Available Multicast juega un papel muy importante para soportar una nueva generación de aplicaciones. En la actualidad y por diferentes razones, técnicas y no técnicas, multicast IP no ha sido totalmente adoptado en Internet. Durante los últimos a˜nos, un área de investigación activa es la de implementar este tipo de tráfico desde la perspectiva del nivel de aplicación, donde la funcionalidad de multicast no es responsabilidad de los enrutadores sino de los hosts, a lo que se le conoce como Multicast Overlay Network (MON. En este artículo se plantea el enrutamiento en MON como un problema de Optimización Multiobjetivo (MOP donde se optimizan dos funciones: 1 el retardo total extremo a extremo del árbol multicast, y 2 la máxima utilización de los enlaces. La optimización simultánea de estas dos funciones es un problema NP completo y para resolverlo se propone utilizar Algoritmos Evolutivos Multiobjetivos (MOEA, específicamente NSGAIMulticast plays an important role in supporting a new generation of applications. At present and for different reasons, technical and non–technical, multicast IP hasn’t yet been totally adopted for Internet. During recent years, an active area of research is that of implementing this kind of traffic in the application layer where the multicast functionality isn´t a responsibility of the routers but that of the hosts, which we know as Multicast Overlay Networks (MON. In this article, routing in an MON is put forward as a multiobjective optimization problem (MOP where two functions are optimized: 1 the total end to end delay of the multicast tree and 2 the maximum link utilization. The simultaneous optimization of these two functions is an NP–Complete problem and to solve this we suggest using Multiobjective Evolutionary Algorithms (MOEA, specifically NSGA–II.

  14. Performance analysis of hybrid WDM-OTDM optical multicast overlay system employing 120 Gbps polarization and subcarrier multiplexed unicast signal with 40 Gbps multicast signal

    Science.gov (United States)

    Singh, Sukhbir; Singh, Surinder

    2017-02-01

    In this paper, we have propose and investigated the performance of hybrid WDM-OTDM optical multicast overlay system which employs 120 Gbps unicast and 40 Gbps multicast data operating over SMF+DCF and amplifier link in C-band. The polarization and subcarrier multiplexed modulation formats are used to obtain 120 Gbps unicast data and DPSK (differential phase shift keying) modulation format for 40 Gbps multicast data transmission. In multicast operation, DPSK data is superimposed on to multiplexed unicast data channels. The impact of extinction ratio, input power and transmission distance on the performance of proposed system in terms of output optical power, BER and Q-factor has been investigated for both unicast and multicast data. We have also concluded that polarization and subcarrier multiplexed modulation formats are promising option to increase per channel capacity and less vulnerable to CD and PMD. In addition, the proposed system using hybrid modulation techniques offers higher bandwidth utilization efficiency at higher per channel data rate than conventional modulation formats.

  15. A Multicast Routing Algorithm for Datagram Service in Delta LEO Satellite Constellation Networks

    Directory of Open Access Journals (Sweden)

    Yanpeng Ma

    2014-04-01

    Full Text Available Satellites can broadcast datagram over wide areas, therefore, the satellite network has congenital advantages to implement multicast service. LEO satellite has the property of efficient bandwidth usage, lower propagation delay and lower power consumption in the user terminals and satellites. Therefore, the constellation network composed by LEO satellites is an essential part of future satellite communication networks. In this paper, we propose a virtual center based multicast (VCMulticast routing algorithm for LEO satellite constellation network. The algorithm uses the geographic center information of group users to route multicast datagrams, with less memory, computer power and signaling overhead. We evaluate the delay and performance of our algorithm by means of simulations in the OPENET simulator. The results indicate that the delay of the proposed multicast method exceeds the minimum propagation by at most 29.1% on the average, which is a quite acceptable achievement, considering the resource overhead reduction that can be introduced by our proposal

  16. A New Scheme for MPLS Supporting IP Multicast and Its Validation

    Institute of Scientific and Technical Information of China (English)

    LONG Keping; ZHANG Zhongshan; WANG Wendong; CHENG Shiduan

    2001-01-01

    MPLS that combines the flexibility ofLayer3 routing with QoS supporting of Layer2 switch-ing is being widely developed. Unfortunately, exist-ing MPLS specification can only support unicast well,but is lack of supporting multicast. The main dif-ficulty of MPLS supporting multicast is the bindinglabels to multicast FEC. This paper mainly presentsa new scheme that MPLS supports IP multicast rout-ing protocol. In the proposed mechanism, the labeldistribution is triggered by traffic and not by controlmessages. This scheme makes the network's scalabil-ity and dynamic characteristic better than the schemewhose label distribution is triggered by control mes-sages. The simulation results validate that this schemecan work well both in normal network and in the con-dition of higher link-loss-rate.

  17. A Genetic Algorithm for Delay-constrained Least-cost Multicast Routing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The delay-constrained least-cost multicast routing problem is introduced and then a related genetic algorithm is proposed. Finally, simulation results are shown to prove that the genetic algorithm is fast and effective.

  18. Performance Analysis of QoS Multicast Routing in Mobile Ad Hoc Networks Using Directional Antennas

    Directory of Open Access Journals (Sweden)

    Yuan Li

    2010-12-01

    Full Text Available in this paper, a quality of service (QoS multicast routing protocol in mobile ad hoc networks (MANETs by using directional antennas has been presented. Many important applications, such as audio/video conferencing, require the quality of service guarantee. Directional antenna technology provides the capability for considerable increase in spatial reuse, which increases the efficiency of communication. This paper studies TDMA-based timeslot allocation and directional antennas, and presents an effective algorithm for calculating bandwidth of a multicast tree. We also propose a novel on-demand QoS multicasting routing algorithm in TDMA-based mobile ad hoc networks using directional antennas. The simulation result shows the performance of this QoS multicast routing algorithm in TDMA-based mobile ad hoc networks using directional antennas.

  19. Relay Ability Estimation and Topology Control Using Multidimensional Context Parameters for Mobile P2P Multicast

    Directory of Open Access Journals (Sweden)

    Kubo Hiroyuki

    2011-01-01

    Full Text Available We focus on mobile P2P multicast, in which mobile end nodes not only act as receivers but also relay the received stream forward to others. In mobile P2P multicast, negative effects caused by the change of available bandwidth and the disconnection of mobile nodes are propagated to the downstream nodes. To solve this problem, we developed a novel node-allocation framework using the multidimensional context parameters of each mobile node, which include available bandwidth, disconnection rate, and the remaining battery capacity. Considering the significance of each parameter, our method integrates these parameters into a single parameter called relay ability. Taking the relay ability into account, each node is allocated to the multicast topology to minimize the negative effects mentioned above. To test our method, we applied our framework to conventional P2P multicast topology and show the results from comparative evaluations through computer simulation.

  20. A Hybrid Multicast-Unicast Infrastructure for Efficient Publish-Subscribe in Enterprise Networks

    CERN Document Server

    Bickson, Danny; Naaman, Nir; Tock, Yoav

    2009-01-01

    One of the main challenges in building a large scale publish-subscribe infrastructure in an enterprise network, is to provide the subscribers with the required information, while minimizing the consumed host and network resources. Typically, previous approaches utilize either IP multicast or point-to-point unicast for efficient dissemination of the information. In this work, we propose a novel hybrid framework, which is a combination of both multicast and unicast data dissemination. Our hybrid framework allows us to take the advantages of both multicast and unicast, while avoiding their drawbacks. We investigate several algorithms for computing the best mapping of publishers' transmissions into multicast and unicast transport. Using extensive simulations, we show that our hybrid framework reduces consumed host and network resources, outperforming traditional solutions. To insure the subscribers interests closely resemble those of real-world settings, our simulations are based on stock market data and on recor...

  1. CD1-Restricted T Cells at the Crossroad of Innate and Adaptive Immunity

    Science.gov (United States)

    Pereira, Catia S.

    2016-01-01

    Lipid-specific T cells comprise a group of T cells that recognize lipids bound to the MHC class I-like CD1 molecules. There are four isoforms of CD1 that are expressed at the surface of antigen presenting cells and therefore capable of presenting lipid antigens: CD1a, CD1b, CD1c, and CD1d. Each one of these isoforms has distinct structural features and cellular localizations, which promotes binding to a broad range of different types of lipids. Lipid antigens originate from either self-tissues or foreign sources, such as bacteria, fungus, or plants and their recognition by CD1-restricted T cells has important implications in infection but also in cancer and autoimmunity. In this review, we describe the characteristics of CD1 molecules and CD1-restricted lipid-specific T cells, highlighting the innate-like and adaptive-like features of different CD1-restricted T cell subtypes. PMID:28070524

  2. Multicast Routing with End-to-End Delay forNumber of Tardy Member of Multicast Group

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xianwei; CHEN Changjia; ZHU Gang

    2001-01-01

    The problem of constructing multi-cast trees to meet the quality of service requirementsof real-time interactive applications operating in high-speed packet-switched environments is presented.Inparticular,the new concept of the delay is redefined,that is,the concepts of delay of the link (or the path)and delay of destination are distinguished.Routineend-to-end delay is defined as "deadline delay" or"bounded delay" and the delay of number of tardymember in this paper is defined as "slack delay".Theslack delay of the destination refers to the feature thatthe accumulated delay from the source to any destina-tion along the tree may exceed the value of slack delay.The problem of determining such a constrained tree isNP-complete.A heuristic presented demonstrates agood average case behavior in terms of the two objec-tives.We also show that it is possible to dynamicallyreorganize the initial tree in response to changes in thedestination set,in a way that is minimally disruptiveto the multicast session.

  3. Fast Multicast on Multistage Interconnection Networks Using Multi-Head Worms

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaodong; XU Ming; ZHOU Xingming

    1999-01-01

    Abstract This paper proposes a new approach forimplementing fast multicast on multistage interconnection networks (MINs)with multi-head worms. For an MIN with n stages of k×k switches,a singlemulti-head worm can cover an arbitrary set of destinations with asingle communication start-up. Compared with schemes using unicastmessages, this approach reduces multicast latency significantly andperforms better than multi-destination worms.

  4. A Multicast Protocol Utilizing On-demand Routing Strategy for MPRN

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper proposes a multicast protocol utilizing ondemand routing strategy for mobile packet radio network. It does not maintain permanent route tables with full topological views. Instead, multicast senders apply on-demand procedures to dynamically discover routes and build forwarding group in this protocol. The data packets are propagated by each forwarding group member via scoped flooding, so the protocol can reduce network bandwidth overhead and avoid the propagation of potentially large routing updates throughout the network.

  5. Pseudo-Cycle-Based Multicast Routing in Wormhole-Routed Networks

    Institute of Scientific and Technical Information of China (English)

    SONG JianPing (宋建平); HOU ZiFeng (侯紫峰); XU Ming (许铭)

    2003-01-01

    This paper addresses the problem of fault-tolerant multicast routing in wormholerouted multicomputers. A new pseudo-cycle-based routing method is presented for constructing deadlock-free multicast routing algorithms. With at most two virtual channels this technique can be applied to any connected networks with arbitrary topologies. Simulation results show that this technique results in negligible performance degradation even in the presence of a large number of faulty nodes.

  6. A subtree-based approach to failure detection and protection for multicast in SDN#

    Institute of Scientific and Technical Information of China (English)

    Vignesh RENGANATHAN RAJA; Chung-Horng LUNG; Abhishek PANDEY; Guo-ming WEI; Anand SRINIVASAN

    2016-01-01

    Software-defined networking (SDN) has received tremendous attention from both industry and academia. The cen-tralized control plane in SDN has a global view of the network and can be used to provide more effective solutions for complex problems, such as traffic engineering. This study is motivated by recent advancement in SDN and increasing popularity of mul-ticasting applications. We propose a technique to increase the resiliency of multicasting in SDN based on the subtree protection mechanism. Multicasting is a group communication technology, which uses the network infrastructure efficiently by sending the data only once from one or multiple sources to a group of receivers that share a common path. Multicasting applications, e.g., live video streaming and video conferencing, become popular, but they are delay-sensitive applications. Failures in an ongoing mul-ticast session can cause packet losses and delay, which can significantly affect quality of service (QoS). In this study, we adapt a subtree-based technique to protect a multicast tree constructed for OpenFlow switches in SDN. The proposed algorithm can detect link or node failures from a multicast tree and then determines which part of the multicast tree requires changes in the flow table to recover from the failure. With a centralized controller in SDN, the backup paths can be created much more effectively in com-parison to the signaling approach used in traditional multiprotocol label switching (MPLS) networks for backup paths, which makes the subtree-based protection mechanism feasible. We also implement a prototype of the algorithm in the POX controller and measure its performance by emulating failures in different tree topologies in Mininet.

  7. Brief Announcement: Decentralized Construction of Multicast Trees Embedded into P2P Overlay Networks based on Virtual Geometric Coordinates

    CERN Document Server

    Andreica, Mugurel Ionut; Sambotin, Ana-Delia; Tapus, Nicolae; 10.1145/1835698.1835766

    2010-01-01

    In this paper we consider the problem of efficiently constructing in a fully distributed manner multicast trees which are embedded into P2P overlays using virtual geometric node coordinates. We consider two objectives: to minimize the number of messages required for constructing a multicast tree by using the geometric properties of the P2P overlay, and to construct stable multicast trees when the lifetime durations of the peers are known.

  8. Minimum-Energy All-to-All Multicasting in Multi-hop Wireless Networks

    CERN Document Server

    Han, Kai; Luo, Jun

    2011-01-01

    Designing energy-efficient all-to-all multicasting protocols is of of great importance for multi-hop wireless networks such as wireless sensor networks and wireless ad hoc networks. In an all-to-all multicast session, there exists a set of wireless destination nodes, and each destination node needs to send some data packets to all other destination nodes. We consider the problem of building a shared multicast tree spanning the destination nodes such that the total energy consumption of realizing an all-to-all multicast session using the shared multicast tree is minimized. Since building such a multicast tree has been proved to be NP-complete, we provide both centralized and distributed approximation algorithms with provable approximation ratios for it. When the transmission power of each wireless node is fixed, our centralized and distributed algorithms have the approximation ratios of $4ln(\\Delta+1)+7$ and 13, respectively, where $\\Delta$ is the maximum node degree in the network. When the transmission power...

  9. QoS Supported IPTV Service Architecture over Hybrid-Tree-Based Explicit Routed Multicast Network

    Directory of Open Access Journals (Sweden)

    Chih-Chao Wen

    2012-01-01

    Full Text Available With the rapid advance in multimedia streaming and multicast transport technology, current IP multicast protocols, especially PIM-SM, become the major channel delivery mechanism for IPTV system over Internet. The goals for IPTV service are to provide two-way interactive services for viewers to select popular program channel with high quality for watching during fast channel surfing period. However, existing IP multicast protocol cannot meet above QoS requirements for IPTV applications between media server and subscribers. Therefore, we propose a cooperative scheme of hybrid-tree based on explicit routed multicast, called as HT-ERM to combine the advantages of shared tree and source tree for QoS-supported IPTV service. To increase network utilization, the constrained shortest path first (CSPF routing algorithm is designed for construction of hybrid tree to deliver the high-quality video stream over watching channel and standard quality over surfing channel. Furthermore, the Resource Reservation Protocol- Traffic Engineering (RSVP-TE is used as signaling mechanism to set up QoS path for multicast channel admission control. Our simulation results demonstrated that the proposed HT-ERM scheme outperforms other multicast QoS-based delivery scheme in terms of channel switching delay, resource utilization, and blocking ratio for IPTV service.

  10. Distributed and Location-Based Multicast Routing Algorithms for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Hakki Bagci

    2009-01-01

    Full Text Available Multicast routing protocols in wireless sensor networks are required for sending the same message to multiple different destinations. In this paper, we propose two different distributed algorithms for multicast routing in wireless sensor networks which make use of location information of sensor nodes. Our first algorithm groups the destination nodes according to their angular positions and forwards the multicast message toward each group in order to reduce the number of total branches in multicast tree which also reduces the number of messages transmitted. Our second algorithm calculates an Euclidean minimum spanning tree at the source node by using the positions of the destination nodes. The multicast message is forwarded to destination nodes according to the calculated MST. This helps in reducing the total energy consumed for delivering the message to all destinations by decreasing the number of total transmissions. Evaluation results show that the algorithms we propose are scalable and energy efficient, so they are good candidates to be used for multicasting in wireless sensor networks.

  11. ARRANGING MULTICAST FORWARDING TABLE IN CLASS SEQUENCE IN TERNARY-CAM FOR LINE-SPEED LOOKUP

    Institute of Scientific and Technical Information of China (English)

    Li Yufeng; Qiu Han; Lan Julong; Wang Binqiang

    2009-01-01

    PIM-SM (Protocol Independent Multicast-Sparse Mode) is a main multicast routing protocol in the IPv6 (Internet Protocol version 6). It can use either a shared tree or a shortest path tree to deliver data packets, consequently the multicast IP lookup engine requires, in some cases, two searches to get a correct lookup result according to its multicast forwarding rule, and it may result in a new requirement of doubling the lookup speed of the lookup engine. The ordinary method to satisfy this requirement in TCAM (Ternary Content Addressable Memory) based lookup engines is to exploit parallelism among multiple TCAMs. However, traditional parallel methods always induce more resources and higher design difficulty. We propose in this paper a novel approach to solve this problem. By arranging multicast forwarding table in class sequence in TCAM and making full use of the intrinsic characteristic of the TCAM, our approach can get the right lookup result with just one search and a single TCAM, while keeping the hardware of lookup engine unchanged. Experimental results have shown that the approach make it possible to satisfy forwarding IPv6 multicast packets at the full link rate of 20 Gb/s with just one TCAM with the current TCAM chip.

  12. MULTICAST-SUPPORTED FAST HANDOVER FOR Proxy Mobile IPv6

    Directory of Open Access Journals (Sweden)

    V. Berlin Hency

    2013-01-01

    Full Text Available Proxy Mobile IPv6 is a network-based mobility management protocol which is attractive as it does not require the participation of mobile nodes in mobility-related signaling. Unlike the host based approaches like Mobile IPv6, in PMIPv6 the Mobility Access Gateway (MAG is responsible for tracking the movements of Mobile Node (MN and to initiate the handover process. In this study, a novel method of multicasting the data packets to both the previous and the new MAGs by Local Mobility Anchor (LMA during the handover process is proposed. The experimental results show that the handover delay is greatly reduced when compared to the existing approaches and the packet loss during the handover process is reduced.

  13. FAIRNESS OF SHARING PROTECTION FOR MULTICAST IN WDM NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Li Yonggang; Jin Yaohui; Li Lemin

    2008-01-01

    In this paper,the sharing schemes of multicast in survivable Wavelength-Division Multiplexed (WDM) networks are studied and the concept of Shared Risk Link Group (SRLG) is considered.While the network resources are shared by the backup paths,the sharing way is possible to make the backup paths selfish. This selfishness leads the redundant hops of the backup route and a large number of primary lightpaths to share one backup link. The sharing schemes,especially,the self-sharing and cross-sharing,are investigated to avoid the selfishness when computing the backup light-tree. In order to decrease the selfishness of the backup paths,it is important to make the sharing links fair to be used.There is a trade-off between the self-sharing and cross-sharing,which is adjusted through simulation to adapt the sharing degree of each sharing scheme and save the network resources.

  14. A Fast Handover Scheme for Multicasting in IPv6 based Mobile Ad hoc Networks

    Directory of Open Access Journals (Sweden)

    H. Parveen Sultana

    2011-01-01

    Full Text Available Abstract: Problem statement: In the previous researches, steps were taken to resolve the problems of multicasting, after several discussions. Actually these issues were raised, while multicasting packets from Internet Protocol (IP to Mobile Nodes (MN. On the other hand, there is very little concern about the problem of packet loss reduction. Sometimes the occurrence of multicast service chaos is ignored during handovers. Therefore in this study it has been tried to explain the optimal multicast technique for Mobile IPv6 (MIPv6 to diminish the required amendment to the existing fast handover. Approach: An alternate method is suggested in Fast handover for MIPv6 (FMIPv6 to lessen the packet losses during handovers, before tunneling. Based on the qualities of the multicast subscription techniques for the Mobile IPv6 (MIPv6, multicast upholds method for FMIPv6. MIPv6 in general comprise two types of multicasting techniques, which are related to Home Agent (HA and Foreign Agent (FA. These techniques help the MN to obtain the packets in roaming location referred as Foreign Network (FN, which is being forwarded by the Core Network (CN. But due to the handover latency problem MN have to experience packet loss while switching between any two Access Routers (AR. A protocol has been designed to conquer the issue of packet loss in MIPv6. Results and Conclusion: This protocol can be used during joining process in MIPv6 before tunneling to eliminate the IP connectivity time. This implementation allows a mobile node to be connected more quickly at a fresh point of connection, when that mobile node moves with less packet losses.

  15. MDP: Reliable File Transfer for Space Missions

    Science.gov (United States)

    Rash, James; Criscuolo, Ed; Hogie, Keith; Parise, Ron; Hennessy, Joseph F. (Technical Monitor)

    2002-01-01

    This paper presents work being done at NASA/GSFC by the Operating Missions as Nodes on the Internet (OMNI) project to demonstrate the application of the Multicast Dissemination Protocol (MDP) to space missions to reliably transfer files. This work builds on previous work by the OMNI project to apply Internet communication technologies to space communication. The goal of this effort is to provide an inexpensive, reliable, standard, and interoperable mechanism for transferring files in the space communication environment. Limited bandwidth, noise, delay, intermittent connectivity, link asymmetry, and one-way links are all possible issues for space missions. Although these are link-layer issues, they can have a profound effect on the performance of transport and application level protocols. MDP, a UDP-based reliable file transfer protocol, was designed for multicast environments which have to address these same issues, and it has done so successfully. Developed by the Naval Research Lab in the mid 1990's, MDP is now in daily use by both the US Post Office and the DoD. This paper describes the use of MDP to provide automated end-to-end data flow for space missions. It examines the results of a parametric study of MDP in a simulated space link environment and discusses the results in terms of their implications for space missions. Lessons learned are addressed, which suggest minor enhancements to the MDP user interface to add specific features for space mission requirements, such as dynamic control of data rate, and a checkpoint/resume capability. These are features that are provided for in the protocol, but are not implemented in the sample MDP application that was provided. A brief look is also taken at the status of standardization. A version of MDP known as NORM (Neck Oriented Reliable Multicast) is in the process of becoming an IETF standard.

  16. Borrelia burgdorferi infection regulates CD1 expression in human cells and tissues via IL1-β.

    Science.gov (United States)

    Yakimchuk, Konstantin; Roura-Mir, Carme; Magalhaes, Kelly G; de Jong, Annemieke; Kasmar, Anne G; Granter, Scott R; Budd, Ralph; Steere, Allen; Pena-Cruz, Victor; Kirschning, Carsten; Cheng, Tan-Yun; Moody, D Branch

    2011-03-01

    The appearance of group 1 CD1 proteins (CD1a, CD1b and CD1c) on maturing myeloid DC is a key event that converts myeloid DC to effective lipid APC. Here, we show that Borrelia burgdorferi, the causative agent of Lyme disease, triggers appearance of group 1 CD1 proteins at high density on the surface of human myeloid DC during infection. Within human skin, CD1b and CD1c expression was low or absent prior to infection, but increased significantly after experimental infections and in erythema migrans lesions from Lyme disease patients. The induction of CD1 was initiated by borrelial lipids acting through TLR-2 within minutes, but required 3 days for maximum effect. The delay in CD1 protein appearance involved a multi-step process whereby TLR-2 stimulated cells release soluble factors, which are sufficient to transfer the CD1-inducing effect in trans to other cells. Analysis of these soluble factors identified IL-1β as a previously unknown pathway leading to group 1 CD1 protein function. This study establishes that upregulation of group 1 CD1 proteins is an early event in B. burgdorferi infection and suggests a stepwise mechanism whereby bacterial cell walls, TLR activation and cytokine release cause DC precursors to express group 1 CD1 proteins.

  17. CD1c+ blood dendritic cells have Langerhans cell potential.

    Science.gov (United States)

    Milne, Paul; Bigley, Venetia; Gunawan, Merry; Haniffa, Muzlifah; Collin, Matthew

    2015-01-15

    Langerhans cells (LCs) are self-renewing in the steady state but repopulated by myeloid precursors after injury. Human monocytes give rise to langerin-positive cells in vitro, suggesting a potential precursor role. However, differentiation experiments with human lineage-negative cells and CD34(+) progenitors suggest that there is an alternative monocyte-independent pathway of LC differentiation. Recent data in mice also show long-term repopulation of the LC compartment with alternative myeloid precursors. Here we show that, although monocytes are able to express langerin, when cultured with soluble ligands granulocyte macrophage colony-stimulating factor (GM-CSF), transforming growth factor β (TGFβ), and bone morphogenetic protein 7 (BMP7), CD1c(+) dendritic cells (DCs) become much more LC-like with high langerin, Birbeck granules, EpCAM, and E-cadherin expression under the same conditions. These data highlight a new potential precursor function of CD1c(+) DCs and demonstrate an alternative pathway of LC differentiation that may have relevance in vivo.

  18. Neurobehavioural Effects of Hypergravity Exposure in CD-1 Mice

    Science.gov (United States)

    Santucci, Daniela; Francia, Nadia; Aloe, Luigi; Enrico, Alleva

    The effects of spaceflight on the nervous system physiology could have important implications for the prolonged stay outside Earth's gravitational field. In this view, both ground-based and space research using animal models represent useful tools to investigate the impact of gravity (hypergravity, microgravity and weightlessness) on the nervous system and behaviour. Data coming from these studies, besides acquisition of knowledge relevant for spaceflights and pro-longed permanence of both humans and animals in space, could provide insight into basic bio-logical phenomena underlying the plasticity of the nervous system and its adaptive responses to a changing environment. Most ground experiments employing animal models use the paradigm of hypergravity exposure with the expectation that behavioural and physiological reactions to this environment might help to explain reactions to the microgravity challenge faced by or-biting animals. An overview of ground-based experiments set up to investigate the effects of changes of gravitational environment on the neurobehavioural responses of CD-1 mouse will be reported, and will illustrate the short-, medium-and long-term behavioural and neurobiological consequences of hypergravity exposure both at adulthood and during early and late postnatal development. Moreover, since mother-pup interaction is critical for the survival and the devel-opment of neonatal rodents, especially in an extreme environment such as that of space, we characterized, exploiting ethological methods, changes in maternal behaviour of CD-1 outbred mouse dams exposed to mild hypergravity. The results of these experiments will be discussed.

  19. Next Generation Reliable Transport Networks

    DEFF Research Database (Denmark)

    Zhang, Jiang

    of criticality and security, there are certain physical or logical segregation requirements between the avionic systems. Such segregations can be implemented on the proposed avionic networks with different hierarchies. In order to fulfill the segregation requirements, a tailored heuristic approach for solving......This thesis focuses the efforts on ensuring the reliability of transport networks and takes advantages and experiences from the transport networks into the networks for particular purposes. Firstly, the challenges of providing reliable multicast services on Multipath Label Switching......-Transport Profile (MPLS-TP) ring networks are addressed. Through the proposed protection structure and protection switching schemes, the recovery mechanism is enhanced in terms of recovery label consumption, operation simplicity and fine traffic engineering granularity. Furthermore, the extensions for existing...

  20. Asymmetric Directional Multicast for Capillary Machine-to-Machine Using mmWave Communications.

    Science.gov (United States)

    Kwon, Jung-Hyok; Kim, Eui-Jik

    2016-01-01

    The huge demand for high data rate machine-to-machine (M2M) services has led to the use of millimeter Wave (mmWave) band communications with support for a multi-Gbps data rate through the use of directional antennas. However, unnecessary sector switching in multicast transmissions with directional antennas results in a long delay, and consequently a low throughput. We propose asymmetric directional multicast (ADM) for capillary M2M to address this problem in mmWave communications. ADM provides asymmetric sectorization that is optimized for the irregular deployment pattern of mulicast group members. In ADM, an M2M gateway builds up asymmetric sectors with a beamwidth of a different size to cover all multicast group members with the minimum number of directional transmissions. The performance of ADM under various simulation environments is evaluated through a comparison with legacy mmWave multicast. The results of the simulation indicate that ADM achieves a better performance in terms of the transmission sectors, the transmission time, and the aggregate throughput when compared with the legacy multicast method.

  1. Mobility Based Key Management Technique for Multicast Security in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    B. Madhusudhanan

    2015-01-01

    Full Text Available In MANET multicasting, forward and backward secrecy result in increased packet drop rate owing to mobility. Frequent rekeying causes large message overhead which increases energy consumption and end-to-end delay. Particularly, the prevailing group key management techniques cause frequent mobility and disconnections. So there is a need to design a multicast key management technique to overcome these problems. In this paper, we propose the mobility based key management technique for multicast security in MANET. Initially, the nodes are categorized according to their stability index which is estimated based on the link availability and mobility. A multicast tree is constructed such that for every weak node, there is a strong parent node. A session key-based encryption technique is utilized to transmit a multicast data. The rekeying process is performed periodically by the initiator node. The rekeying interval is fixed depending on the node category so that this technique greatly minimizes the rekeying overhead. By simulation results, we show that our proposed approach reduces the packet drop rate and improves the data confidentiality.

  2. Optimizing on multiple constrained QoS multicast routing algorithms based on GA

    Institute of Scientific and Technical Information of China (English)

    孙宝林; 李腊元

    2004-01-01

    With the rapid development of Internet, mobile networks and high-performance networking technology,multiple constrained QoS multicast routing optimization in networks with uncertain parameters has become a very important research issue in the areas of networks and distributed systems. It is also a challenging and hard problem to the next generation Internet and high-performance networks, and has attracted the interests of many people. This paper discusses the multiple constrained QoS multicast routing problem, which may deal with the delay, delay jitter,bandwidth and packet loss metrics, and describes a network model for researching the routing problem. The paper mainly presents multiple constrained QoS multicast routing algorithm (MCQMRA), a QoS multicast routing policy for Internet,mobile network or other high-performance networks, which is based on the genetic algorithm (GA) and can provide QoS-sensitive paths in a scalable and flexible wayin the network environment with uncertain parameters. The MCQMRA can also optimize the network resources such as bandwidth, delay, packet loss metrics and can converge to the optimal or near-optimal solution within few iterations, even for the network environment with uncertain parameters. Simulation results show that MCQMRA is an available approach to QoS multicast routing decision.

  3. Mobility based key management technique for multicast security in mobile ad hoc networks.

    Science.gov (United States)

    Madhusudhanan, B; Chitra, S; Rajan, C

    2015-01-01

    In MANET multicasting, forward and backward secrecy result in increased packet drop rate owing to mobility. Frequent rekeying causes large message overhead which increases energy consumption and end-to-end delay. Particularly, the prevailing group key management techniques cause frequent mobility and disconnections. So there is a need to design a multicast key management technique to overcome these problems. In this paper, we propose the mobility based key management technique for multicast security in MANET. Initially, the nodes are categorized according to their stability index which is estimated based on the link availability and mobility. A multicast tree is constructed such that for every weak node, there is a strong parent node. A session key-based encryption technique is utilized to transmit a multicast data. The rekeying process is performed periodically by the initiator node. The rekeying interval is fixed depending on the node category so that this technique greatly minimizes the rekeying overhead. By simulation results, we show that our proposed approach reduces the packet drop rate and improves the data confidentiality.

  4. Self-Organized Hash Based Secure Multicast Routing Over Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Amit Chopra

    2016-02-01

    Full Text Available Multicast group communication over mobile ad hoc networks has various challenges related to secure data transmission. In order to achieve this goal, there is a need to authenticate the group member as well as it is essential to protect the application data, routing information, and other network resources etc. Multicast-AODV (MAODV is the extension of an AODV protocol, and there are several issues related to each multicast network operation. In the case of dynamic group behavior, it becomes more challenging to protect the resources of a particular group. Researchers have developed different solutions to secure multicast group communication, and their proposed solutions can be used for resource protection at different layers i.e. application layer, physical layer, network layer, etc. Each security solution can guard against a particular security threat. This research paper introduced a self-organized hash based secure routing scheme for multicast ad hoc networks. It uses group Diffie-Hellman method for key distribution. Route authentication and integrity, both are ensured by generating local flag codes and global hash values. In the case of any violation, route log is monitored to identify the malicious activities.

  5. A Rough Penalty Genetic Algorithm for Multicast Routing in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Chih-Hao Lin

    2013-01-01

    Full Text Available Multicast routing is an effective way to transmit messages to multiple hosts in a network. However, it is vulnerable to intermittent connectivity property in mobile ad hoc network (MANET especially for multimedia applications, which have some quality of service (QoS requirements. The goal of QoS provisioning is to well organize network resources to satisfy the QoS requirement and achieve good network delivery services. However, there remains a challenge to provide QoS solutions and maintain end-to-end QoS with user mobility. In this paper, a novel penalty adjustment method based on the rough set theory is proposed to deal with path-delay constraints for multicast routing problems in MANETs. We formulate the problem as a constrained optimization problem, where the objective function is to minimize the total cost of the multicast tree subject to QoS constraints. The RPGA is evaluated on three multicast scenarios and compared with two state-of-the-art methods in terms of cost, success rate, and time complexity. The performance analyses show that this approach is a self-adaptive method for penalty adjustment. Remarkably, the method can address a variety of constrained multicast routing problems even though the initial routes do not satisfy all QoS requirements.

  6. Enhanced first-in-first-out-based round-robin multicast scheduling algorithm for input-queued switches

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This study focuses on the multicast scheduling for M × N input-queued switches. An enhanced first-in-first-out -based round-robin multicast scheduling algorithm is proposed with a function of searching deeper into queues to reduce the head-of-line (HOL) blocking problem and thereby the multicast...... out on the decision matrix to reduce the number of transmission for each cell. To reduce the HOL blocking problem, a complement matrix is constructed based on the traffic matrix and the decision matrix, and a process of searching deeper into the queues is carried out to find cells that can be sent...... to the idle outputs. Simulation results show that the proposed function of searching deeper into the queues can alleviate the HOL blocking and as a result reduce the multicast latency significantly. Under both balanced and unbalanced multicast traffic, the proposed algorithm is able to maintain a stable...

  7. Donor states in a semimagnetic Cd1 -xinMnxin Te /Cd1 -xoutMnxout Te Double Quantum Well

    Science.gov (United States)

    Kalpana, Panneer Selvam; Nithiananthi, Perumal; Jayakumar, Kalyanasundaram

    2017-02-01

    The theoretical investigation has been carried out on the binding energy of donor associated with the electrons confined in a Cd1 -xinMnxin Te /Cd1 -xoutMnxout Te Double Quantum Well (DQW) as a function of central barrier width for various well dimensions and impurity locations in the barrier and the well. The magnetic field can act as a tool to continuously change the interwell coupling inside this DQW systems and its effect on donor binding has also been studied. Moreover, the polaronic corrections, which is due to the strong exchange interaction between the magnetic moment of Mn2+ ion and the spin of the confined carrier, to the binding energy of the hydrogenic donor impurity has also been estimated with and without the application of magnetic field. The binding energy of the donor impurity is determined by solving the Schrodinger equation variationally in the effective mass approximation and the effect due to Bound Magnetic Polaron (BMP) is included using mean field theory with the modified Brillouin function. The results are reported and discussed.

  8. CD1a-autoreactive T cells recognize natural skin oils that function as headless antigens

    NARCIS (Netherlands)

    de Jong, A.; Cheng, T.Y.; Huang, S.; Gras, S.; Birkinshaw, R.W.; Kasmar, A.; van Rhijn, I.|info:eu-repo/dai/nl/238098680; Pena-Cruz, V.; Ruan, D.T.; Altman, J.D.; Rossjohn, J.; Moody, D.B.

    2014-01-01

    T cells autoreactive to the antigen-presenting molecule CD1a are common in human blood and skin, but the search for natural autoantigens has been confounded by background T cell responses to CD1 proteins and self lipids. After capturing CD1a-lipid complexes, we gently eluted ligands while preserving

  9. On-the-Fly Coding to Enable Full Reliability Without Retransmission

    CERN Document Server

    Lacan, Jerome

    2008-01-01

    This paper proposes a new reliability algorithm specifically useful when retransmission is either problematic or not possible. In case of multimedia or multicast communications and in the context of the Delay Tolerant Networking (DTN), the classical retransmission schemes can be counterproductive in terms of data transfer performance or not possible when the acknowledgment path is not always available. Indeed, over long delay links, packets retransmission has a meaning of cost and must be minimized.In this paper, we detail a novel reliability mechanism with an implicit acknowledgment strategy that could be used either within these new DTN proposals, for multimedia traffic or in the context of multicast transport protocols. This proposal is based on a new on-the-fly erasure coding concept specifically designed to operate efficient reliable transfer over bi-directional links. This proposal, named Tetrys, allows to unify a full reliability with an error correction scheme. In this paper, we model the performance ...

  10. A rate based congestion control algorithm in networks with coexisting unicast and multicast sessions

    Institute of Scientific and Technical Information of China (English)

    Qian Dong; Jianying Xie

    2003-01-01

    The optimal rate control problem in networks with unicast and multirate multicast sessions is investigated. A penaltyfunction approach is used to solve a convex program formulation of this problem, and then a heuristic rate control algorithm is de-rived. The algorithm is distributed, and suitable both for source-driven unicast sessions and receiver-driven multicast sessions. Toobtain practical viability, the computational burden on core routers as well as end-hosts is kept very low, also is the overhead of net-work congestion feedback. Simulation results show that the algorithm guarantees TCP (Transmission Control Protocol)-based anicastsessions coexisting with multirate multicast sessions in a fair and friendly manner. It is also shown that various fairness criteria ofresource allocation could be achieved by choosing appropriate utility functions, and resource-utilizing efficiencies would be like wisedifferent.

  11. On-demand multicast routing protocol based on node classification in MANET

    Institute of Scientific and Technical Information of China (English)

    DENG Xia; SUN Li-min; WANG Jian-xin; LUO Yu-hong; CHEN Jian-er

    2006-01-01

    An improved on-demand multicast routing protocol(ODMRP), node classification on-demand multicast routing protocol(NC-ODMRP), which is based on node classification in mobile ad hoc networks was proposed. NCODMRP classifies nodes into such three categories as ordinary node, forwarding group(FG) node, neighbor node of FG node according to their history forwarding information. The categories are distinguished with different weights by a weight table in the nodes. NC-ODMRP chooses the node with the highest weight as an FG node during the setup of forwarding group, which reduces a lot of redundant FG nodes by sharing more FG nodes between different sender and receiver pairs. The simulation results show that NC-ODMRP can reduce more than 20% FG number of ODMRP, thus enhances nearly 14% data forwarding efficiency and 12% energy consumption efficiency when the number of multicast senders is more than 5.

  12. Scalable Multicasting over Next-Generation Internet Design, Analysis and Applications

    CERN Document Server

    Tian, Xiaohua

    2013-01-01

    Next-generation Internet providers face high expectations, as contemporary users worldwide expect high-quality multimedia functionality in a landscape of ever-expanding network applications. This volume explores the critical research issue of turning today’s greatly enhanced hardware capacity to good use in designing a scalable multicast  protocol for supporting large-scale multimedia services. Linking new hardware to improved performance in the Internet’s next incarnation is a research hot-spot in the computer communications field.   The methodical presentation deals with the key questions in turn: from the mechanics of multicast protocols to current state-of-the-art designs, and from methods of theoretical analysis of these protocols to applying them in the ns2 network simulator, known for being hard to extend. The authors’ years of research in the field inform this thorough treatment, which covers details such as applying AOM (application-oriented multicast) protocol to IPTV provision and resolving...

  13. On the stability of multicast flow aggregation in IP over optical network for IPTV delivery

    Institute of Scientific and Technical Information of China (English)

    Xuan Luo; Yaohui Jin; Qingji Zeng; Weiqiang Sun; Wei Guo; Weisheng Hu

    2008-01-01

    The stable multicast flow aggregation (MFA) problem in internet protocol (IP) over optical network under the dynamical scenario is studied. Given an optical network topology, there is a set of head ends and access routers attached to the optical network, in which each head end can provide a set of programs (IP multicasting flows) and each access router requests a set of programs, we find a set of stable light-trees to accommodate the optimally aggregated multicast IP flows if the requests of access routers changed dynamically. We introduce a program correlation matrix to describe the preference of end users' requests. As the original MFA problem is NP-complete, a heuristic approach, named most correlated program first (MCPF), is presented and compared with the extended least tree first (ELTF) algorithm which is topologyaware. Simulation results show that MCPF can achieve better performance than ELTF in terms of stability with negligible increment of network resource usage.

  14. A Novel Video Data-Source Authentication Model Based on Digital Watermarking and MAC in Multicast

    Institute of Scientific and Technical Information of China (English)

    ZHAO Anjun; LU Xiangli; GUO Lei

    2006-01-01

    A novel video data authentication model based on digital video watermarking and MAC (message authentication code) in multicast protocol is proposed in this paper. The digital watermarking which composes of the MAC of the significant video content, the key and instant authentication data is embedded into the insignificant video component by the MLUT (modified look-up table) video watermarking technology. We explain a method that does not require storage of each data packet for a time, thus making receiver not vulnerable to DOS (denial of service) attack. So the video packets can be authenticated instantly without large volume buffer in the receivers. TESLA(timed efficient stream loss-tolerant authentication) does not explain how to select the suitable value for d, which is an important parameter in multicast source authentication. So we give a method to calculate the key disclosure delay (number of intervals). Simulation results show that the proposed algorithms improve the performance of data source authentication in multicast.

  15. A Grooming Nodes Optimal Allocation Method for Multicast in WDM Networks

    Directory of Open Access Journals (Sweden)

    Chengying Wei

    2016-01-01

    Full Text Available The grooming node has the capability of grooming multicast traffic with the small granularity into established light at high cost of complexity and node architecture. In the paper, a grooming nodes optimal allocation (GNOA method is proposed to optimize the allocation of the grooming nodes constraint by the blocking probability for multicast traffic in sparse WDM networks. In the proposed GNOA method, the location of each grooming node is determined by the SCLD strategy. The improved smallest cost largest degree (SCLD strategy is designed to select the nongrooming nodes in the proposed GNOA method. The simulation results show that the proposed GNOA method can reduce the required number of grooming nodes and decrease the cost of constructing a network to guarantee a certain request blocking probability when the wavelengths per fiber and transmitter/receiver ports per node are sufficient for the optical multicast in WDM networks.

  16. Impact of Rushing attack on Multicast in Mobile Ad Hoc Network

    CERN Document Server

    Palanisamy, V

    2009-01-01

    A mobile ad hoc network (MANETs) is a self-organizing system of mobile nodes that communicate with each other via wireless links with no fixed infrastructure or centralized administration such as base station or access points. Nodes in a MANETs operate both as host as well as routers to forward packets for each other in a multihop fashion. For many applications in wireless networks, multicasting is an important and frequent communication service. By multicasting, since a single message can be delivered to multiple receivers simultaneously. It greatly reduces the transmission cost when sending the same packet to multiple recipients. The security issue of MANETs in group communications is even more challenging because of involvement of multiple senders and multiple receivers. At that time of multicasting, mobile ad hoc network are unprotected by the attacks of malicious nodes because of vulnerabilities of routing protocols. Some of the attacks are Rushing attack, Blackhole attack, Sybil attack, Neighbor attack ...

  17. Expression of CD1d protein in human testis showing normal and abnormal spermatogenesis.

    Science.gov (United States)

    Adly, Mohamed A; Abdelwahed Hussein, Mahmoud-Rezk

    2011-05-01

    CD1d is a member of CD1 family of transmembrane glycoproteins, which represent antigen-presenting molecules. Immunofluorescent staining methods were utilized to examine expression pattern of CD1d in human testicular specimens. In testis showing normal spermatogenesis, a strong CD1d cytoplasmic expression was seen the Sertoli cells, spermatogonia, and Leydig cells. A moderate expression was observed in the spermatocytes. In testes showing maturation arrest, CD1d expression was strong in the Sertoli cells and weak in spermatogonia and spermatocytes compared to testis with normal spermatogenesis. In Sertoli cell only syndrome, CD1d expression was strong in the Sertoli and Leydig cells. This preliminary study displayed testicular infertility-related changes in CD1d expression. The ultrastructural changes associated with with normal and abnormal spermatogenesis are open for further investigations.

  18. An Efficient Game Form for Multi-rate Multicast Service Provisioning

    CERN Document Server

    Kakhbod, Ali

    2011-01-01

    We consider the decentralized bandwidth/rate allocation problem in multi-rate multicast service provisioning with strategic users. We demonstrate that such a situation is the combination of a market problem and a public good problem. We present a mechanism/game form which possesses the following properties when the users' utilities are concave: (1) It implements in Nash equilibria the solution of the corresponding centralized rate allocation problem in multi-rate multicast service provisioning. (2) It is individually rational. (3) It is budget-balanced at all Nash equilibria of the game induced by the mechanism/game form as well as off equilibrium.

  19. Linear and non-linear video and TV applications using IPv6 and IPv6 multicast

    CERN Document Server

    Minoli, Daniel

    2012-01-01

    Provides options for implementing IPv6 and IPv6 multicast in service provider networks New technologies, viewing paradigms, and content distribution approaches are taking the TV/video services industry by storm. Linear and Nonlinear Video and TV Applications: Using IPv6 and IPv6 Multicast identifies five emerging trends in next-generation delivery of entertainment-quality video. These trends are observable and can be capitalized upon by progressive service providers, telcos, cable operators, and ISPs. This comprehensive guide explores these evolving directions in the TV/v

  20. Multi-Level Round-Robin Multicast Scheduling with Look-Ahead Mechanism

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    In this paper, we propose a multi-level round-robin multicast scheduling (MLRRMS) algorithm with look-ahead (LA) mechanism for N×N input-queued switches. Fan-out splitting is applied, where a multicast cell can be transferred to all its destinations over any number of cell times. The scheduler...... constructs the Traffic Matrix before each cell transmission based on the fan-out vectors of the cells in the queues. A scheduling pointer independently moves on each column of the Traffic Matrix in a round-robin fashion and returns the decision to the Decision Matrix. The sync procedure is carried out...

  1. Improved Multicast Traffic Scheduling Scheme in the Packet-Switching Systems

    Institute of Scientific and Technical Information of China (English)

    SONG Mei-na; SONG Jun-de; LI Hong-wen

    2004-01-01

    This paper proposes a new switching scheme of switch fabric, which is named Multicast-enabled Protocol Agnostic Forwarding Engine (M-PAFE). M-PAFE is a central scheduling crossbar-based switch fabric with embedded Combined Input and Output Queue from the queuing view. An extra switching path is dedicated for multicast cell processing in M-PAFE. And the simulation results are provided to evaluate the performance of M-PAFE in comparison with ESLIP, which is a well-known algorithm implemented in Cisco 12000 routers.

  2. Experimental Evaluation of a Scalable WiFi Multicast Scheme in the ORBIT Testbed

    OpenAIRE

    Bejerano, Yigal; Ferragut, Jaime; Guo, Katherine; Gupta, Varun; Gutterman, Craig; Nandagopal, Thyaga; Zussman, Gil

    2014-01-01

    IEEE 802.11-based wireless local area networks, referred to as WiFi, have been globally deployed and the vast majority of the mobile devices are currently WiFi-enabled. While WiFi has been proposed for multimedia content distribution, its lack of adequate support for multicast services hinders its ability to provide multimedia content distribution to a large number of devices. In earlier work, we proposed a dynamic scheme called AMuSe that selects a subset of the multicast receivers as feedba...

  3. Multicast in Femtocell Networks: A Successive Interference Cancellation Approach

    Directory of Open Access Journals (Sweden)

    Donglin Hu

    2014-09-01

    Full Text Available A femtocell is a small cellular base station (BS, typically used for serving approved users within a small coverage. In this paper, we investigate the problem of data multicast in femtocell networks that incorporates superposition coding (SC and successive interference cancellation (SIC. The problem is to decide the transmission schedule for each BS, as well as the power allocation for the SC layers, to achieve a sufficiently large SNR for each layer to be decodable with SIC at each user. Minimizing the total BS power consumption achieves the goal of “green” communications. We formulate a Mixed Integer Nonlinear Programming (MINLP problem, and then reformulate the problem into a simpler form. Upper and lower performance bounds on the total BS power consumption are derived. Finally, we consider three typical connection scenarios, and develop optimal and nearoptimal algorithms for the three scenarios. The proposed algorithms have low computational complexity, and outperform a heuristic scheme with considerable gains in our simulation study.

  4. Protection of multicast scalable video by secret sharing: simulation results

    Science.gov (United States)

    Eskicioglu, Ahmet M.; Dexter, Scott; Delp, Edward J., III

    2003-06-01

    Security is an increasingly important attribute for multimedia applications that require prevention of unauthorized access to copyrighted data. Two approaches have been used to protect scalable video content in distribution: Partial encryption and progressive encryption. Partial encryption provides protection for only selected portions of the video. Progressive encryption allows transcoding with simple packet truncation, and eliminates the need to decrypt the video packets at intermediate network nodes with low complexity. Centralized Key Management with Secret Sharing (CKMSS) is a recent approach in which the group manager assigns unique secret shares to the nodes in the hierarchical key distribution tree. It allows the reconstruction of different keys by communicating different activating shares for the same prepositioned information. Once the group key is established, it is used until a member joins/leaves the multicast group or periodic rekeying occurs. In this paper, we will present simulation results regarding the communication and processing requirements of the CKMSS scheme applied to scalable video. In particular, we have measured the rekey message size and the processing time needed by the server for each join/leave request and periodic rekey event.

  5. Opportunistic Relay Selection in Multicast Relay Networks using Compressive Sensing

    KAUST Repository

    Elkhalil, Khalil

    2014-12-01

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. However, for relay selection algorithms to make a selection decision, channel state information (CSI) from all cooperating relays is usually required at a central node. This requirement poses two important challenges. Firstly, CSI acquisition generates a great deal of feedback overhead (air-time) that could result in significant transmission delays. Secondly, the fed back channel information is usually corrupted by additive noise. This could lead to transmission outages if the central node selects the set of cooperating relays based on inaccurate feedback information. In this paper, we introduce a limited feedback relay selection algorithm for a multicast relay network. The proposed algorithm exploits the theory of compressive sensing to first obtain the identity of the “strong” relays with limited feedback. Following that, the CSI of the selected relays is estimated using linear minimum mean square error estimation. To minimize the effect of noise on the fed back CSI, we introduce a back-off strategy that optimally backs-off on the noisy estimated CSI. For a fixed group size, we provide closed form expressions for the scaling law of the maximum equivalent SNR for both Decode and Forward (DF) and Amplify and Forward (AF) cases. Numerical results show that the proposed algorithm drastically reduces the feedback air-time and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback channels.

  6. Malignant spinal meningioma in a CD-1 mouse.

    Science.gov (United States)

    Balme, Emmanuelle; Roth, Daniel Robert; Perentes, Elias

    2008-08-01

    Spontaneous meningiomas are extremely rare tumors in small laboratory animals, except in some strains of rats and in the B6C3F1 mouse. We report the case of a male CD-1 mouse in poor health condition, with severe apathy and partial paresis of hindlegs. No macroscopic lesion was noticed at necropsy. Microscopic examination revealed the presence of a malignant meningioma (approximately 3mm in diameter) at the distal lumbar level of the spinal cord, invading the vertebral canal, and bilaterally the ventral and dorsal nerve roots and the dorsal root ganglia. The tumor displayed highly cellular sheets of polygonal cells with a well-delineated, abundant, eosinophilic cytoplasm and scarce fibrovascular stroma; epithelioid and sarcomatous areas were also present. The mitotic activity was moderate. Tumor cells expressed vimentin immunoreactivity and were negative for periodic acid-Schiff (PAS), silver impregnation for reticulin, chromogranin A, glial fibrillary acidic protein (GFAP), cytokeratin (CK) and S-100 protein. The diagnosis of malignant spinal meningioma was based on the morphologic features of the neoplasm, the evidence of local invasion and the immunohistochemical results.

  7. Intramolecular electron transfer in Pseudomonas aeruginosa cd(1) nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Brunori, Maurizio; Cutruzzolà, Francesca

    2009-01-01

    nitrite reductase has been determined in both fully oxidized and reduced states. Intramolecular electron transfer (ET), between c and d(1) hemes is an essential step in the catalytic cycle. In earlier studies of the Pseudomonas stutzeri enzyme, we observed that a marked negative cooperativity......The cd(1) nitrite reductases, which catalyze the reduction of nitrite to nitric oxide, are homodimers of 60 kDa subunits, each containing one heme-c and one heme-d(1). Heme-c is the electron entry site, whereas heme-d(1) constitutes the catalytic center. The 3D structure of Pseudomonas aeruginosa......-controlled bimolecular process, followed by unimolecular electron equilibration between the c and d(1) hemes (k(ET) = 4.3 s(-1) and K = 1.4 at 298 K, pH 7.0). In the case of the mutant, the latter ET rate was faster by almost one order of magnitude. Moreover, the internal ET rate dropped (by approximately 30-fold...

  8. Zerumbone modulates CD1d expression and lipid antigen presentation pathway in breast cancer cells.

    Science.gov (United States)

    Shyanti, Ritis K; Sehrawat, Anuradha; Singh, Shivendra V; Mishra, J P N; Singh, Rana P

    2017-10-01

    Natural Killer T (NKT) cells based cancer immunotherapy is an evolving area of cancer therapy, but tumors escape from this treatment modality by altering CD1d expression and its antigen presentation pathway. Here, we have studied the relation of CD1d expression in various breast cancer cell lines to their viability and progression. We observed a novel phenomenon that CD1d expression level increases with the progressive stage of the cancer. A small molecule, zerumbone (ZER) caused down-regulation of CD1d that was accompanied by breast cancer cell growth in vitro. The growth inhibitory effect of ZER against breast cancer cells was augmented by treatment with anti-CD1d mAb. This effect was mediated by G1-phase cell cycle arrest and apoptosis induction coupled with an increase in mitochondrial membrane depolarization. CD1d expression and cell proliferation were inhibited by both CD1d siRNA and ZER. The α-galactosylceramide, a ligand for CD1d, showed increased CD1d expression as well as cell proliferation which was opposite to the effects of ZER. This study shows that, CD1d overexpression is associated with the progressive stages of breast cancer and ZER could be an adjuvant to potentiate cancer immunotherapy. Copyright © 2017. Published by Elsevier Ltd.

  9. Algoritmos genéticos multiobjetivos aplicados ao roteamento multicast com qualidade de serviço

    OpenAIRE

    Vita, Stéfano Schwenck Borges Vale

    2009-01-01

    Roteamento multicast é uma maneira eficaz de se comunicar entre múltiplos roteadores em redes de computadores. Geralmente, a Qualidade de Serviço (QoS) é exigida como garantia na maior parte das aplicações multicast. Vários pesquisadores têm investigado a aplicação dos Algoritmos Genéticos em roteamento multicast com restrições QoS. Os ambientes evolutivos de roteamento que são propostos neste trabalho empregam uma abordagem multiobjetivos adotando o conceito de Ótimo de Pareto...

  10. Integrated all-optical wavelength multicasting for 40 Gbit/s PDM-QPSK signals using a single silicon waveguide

    Science.gov (United States)

    Feng, Xianglian; Wu, Zhihang; Wang, Xiaoyan; Gao, Shiming

    2017-09-01

    All-optical wavelength multicasting is presented and experimentally demonstrated for 40 Gbit/s polarization-division-multiplexed (PDM) nonreturn-to-zero quadrature phase-shift keying (QPSK) signals using four-wave mixing (FWM) with angled-polarization pumps in a silicon waveguide. Five multicast channels are obtained on the generated idlers. The eye diagrams, constellation diagrams, and bit error rates (BERs) of the QPSK sequences on the two polarization states are measured for each wavelength channel. The power penalties of all these multicast QPSK sequences on x or y polarization state are less than 2.0 dB at the BER of 3 × 10-3.

  11. Out-of-Sequence Preventative Cell Dispatching for Multicast Input-Queued Space-Memory-Memory Clos-Network

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This paper proposes two out-of-sequence (OOS) preventative cell dispatching algorithms for the multicast input-queued space-memory-memory (IQ-SMM) Clos-network switch architecture, i.e. the multicast flow-based DSRR (MF-DSRR) and the multicast flow-based round-robin (MFRR). Treating each cell...... independently, the desynchronized static round-robin (DSRR) cell dispatching scheme can evenly distribute cells to the central switching modules, however, its frequent change of the input switching module connection pattern causes a serious OOS problem to the IQ-SMM architecture. Therefore large reassembly...

  12. Quick Recovery from Link Failures using Enhanced On-demand Multicast Routing Protocol

    Directory of Open Access Journals (Sweden)

    S. Muthumari Lakshmi

    2015-03-01

    Full Text Available The aim of this study is to reduce the number of link failures and provide a quick recovery mechanism in MANETs. Multicasting is one of the greatest issues among MANETs due to the seamless variations in topology and link dynamics. Due to the wireless nature of the network, the nodes are under the compulsion to perform communication at adverse situations for any emergency or defense operations. The On Demand Multicast Routing Protocol (ODMRP is one of the solutions proposed to avoid the multicasting problem in Wireless Mobile Ad hoc Network. In order to avoid excessive flooding of control messages in the network, Enhanced ODMRP was proposed that introduced short time frames to wait until the refresh messages are flooded. In this study, we propose a quick recovery mechanism that along with the EODMRP helps in the quick recovery from route failures and increases performance in the network. An analysis of the EODMRP protocol for multicasting in MANETs is presented along with the proposed quick recovery mechanism using simulations in the network simulator.

  13. A hybrid ACO/PSO based algorithm for QoS multicast routing problem

    Directory of Open Access Journals (Sweden)

    Manoj Kumar Patel

    2014-03-01

    Full Text Available Many Internet multicast applications such as videoconferencing, distance education, and online simulation require to send information from a source to some selected destinations. These applications have stringent Quality-of-Service (QoS requirements that include delay, loss rate, bandwidth, and delay jitter. This leads to the problem of routing multicast traffic satisfying QoS requirements. The above mentioned problem is known as the QoS constrained multicast routing problem and is NP Complete. In this paper, we present a swarming agent based intelligent algorithm using a hybrid Ant Colony Optimization (ACO/Particle Swarm Optimization (PSO technique to optimize the multicast tree. The algorithm starts with generating a large amount of mobile agents in the search space. The ACO algorithm guides the agents’ movement by pheromones in the shared environment locally, and the global maximum of the attribute values are obtained through the random interaction between the agents using PSO algorithm. The performance of the proposed algorithm is evaluated through simulation. The simulation results reveal that our algorithm performs better than the existing algorithms.

  14. Multicast contention resolution based on time-frequency joint scheduling in elastic optical switching networks

    Science.gov (United States)

    Liu, Huanlin; Li, Yuan; Peng, Han; Huang, Jun; Kong, Deqian

    2017-01-01

    Resolving the optical multicast contention in optical switch node is an effective approach to improve the performance of elastic optical multicast switch. An optical node architecture integrating with output shared all-optical Orthogonal Frequency Division Multiplexing (OFDM) network coding technology and shared feedback fiber delay lines (FDLs) buffer is designed. And a time-frequency joint scheduling strategy (TFJSS) is proposed. In TFJSS, the maximal weighted independent set algorithm is used to select the output packets with no overlapping spectrum among the contending multicast packets. The remaining contention packets are compressed by OFDM network coding with all-optical XOR operation. Hence, the contention is avoided in spectrum domain by encoding the contending unicast/multicast packets and changing the carrier frequency of encoded packets. If the network coding cannot successfully resolve the contending packets, the shared feedback FDLs are called to address the contention in time domain. Compared with the existing node architecture and scheduling algorithm, the simulation results show that the proposed architecture and the TFJSS can reduce the packet loss probability with low delay largely.

  15. Range Detection Multicast Routing Protocol for Mobile Ad-Hoc Networks

    Directory of Open Access Journals (Sweden)

    K. Duraiswamy

    2012-01-01

    Full Text Available Problem statement: Many efforts have been implemented towards the Group membership management on multicast routing in MANETs, but the difficulties associated with Group membership management are still existed. Approach: Maintaining endurance of Group Leader (GL in multicasting routing has been a great challenge to all the protocol having been invented so far. Results: This study provides the RDMP algorithm for persistency of Group Leader within the group. Nodes perform very active in exchanging the Data and Control packet when they mobile within the transmission range. Range Detection Multicast Protocol (RDMP focuses on dynamic topology of nodes and uses detection mechanism based on transmission range within the group. Instead of having a separate external node to monitor on Group leadership, a node within the transmission range acts as a Leadership Track Node (LTN, Group Leader manages the group member with the aid provided by LTN and thus control over head shared among them. LTN keeps track of mobility of Group Leader and send alert message when Group Leader moves out of Transmission range and also holds the list of address of all other Group Leader which are adjacent to it. Routing control packet and data packet are regulated with minimum control over head. Conclusion/Recommendations: Our simulation results under increasing group size demonstrate endurance of Group leader for longer period of time, joining delay for multicast group is very low, normalized control over head and minimizing number of hops in maintain average path length.

  16. Exploiting the In-Network Capabilities of Multicast to Discover Proximate IPTV Channels

    Directory of Open Access Journals (Sweden)

    William Donnelly

    2010-09-01

    Full Text Available IPTV has become the next generation of television due, in part, to its ability to support features that have been lacking in conventional broadcasting—for example, end-user interactivity, personalisation and localisation. Providers are also searching for the most efficient delivery methods to provide the greatest amount of contents at the lowest cost. At present IPTV uses IP multicast to deliver live TV channels in an over-provisioned walled-garden network due to issues of deploying multicast and QoS challenges in the public Internet. However, IPTV is likely to shift into some parts of the public Internet in the future as a managed service. Multicast routing is performed on a per-session destination-address basis so each router maintains a table of all of the multicast addresses to which the content is being forwarded. We exploit this information to discover and join the in-progress channels of geographically proximate users and to create a new incentivised premium service in future IPTV networks called ProxyTV. This approach is expected to minimise network bandwidth requirements as it enables ISPs to optimise bandwidth on their edge networks. This becomes increasingly significant as TV content consumes more and more bandwidth, especially with the onset of HD and 3D capabilities. In this paper, we have presented in detail the concept with the results of a survey and an analysis of network traffic to justify the proposed approach.

  17. Efficient round-robin multicast scheduling for input-queued switches

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Yu, Hao; Ruepp, Sarah Renée

    2014-01-01

    problem. Using a separate queue for each output port at an input to reduce the HOL blocking, that is, the virtual output queuing discipline, increases the implementation complexity, which limits the scalability. Given the increasing link speed and network capacity, a low-complexity yet efficient multicast...

  18. End to End Delay Improvement in Heterogeneous Multicast Network using Genetic Optimization

    Directory of Open Access Journals (Sweden)

    V. Chandrasekar

    2012-01-01

    Full Text Available Problem statement: Multicast is a concept of group communication which refers to transmitting the same data or messages from a source to multiple destinations in the network. This one-to-many group communication is a generalization of the concepts of one-to-one unicast and one-to-all broadcast. To deliver data from the sender to all receivers efficiently, routing plays an important role in multicast communication. In QoS multicast, every receiver must receive the data within their own specified QoS constraints. This becomes challenging especially if the network is a heterogeneous network made up of wired and wireless devices. Approach: This study investigates the performance of Protocol Independent Multicast-Sparse Mode (PIM-SM protocol in a heterogeneous network running an video conferencing application and proposes an enhanced routing protocol using Genetic Optimizing techniques to improve QOS parameters in the wireless part. Results and Conclusion: Extensive simulations were carried out using the proposed technique and existing PIM-SM. The proposed optimization technique not only improves the throughput of the network but also decreased the end to end delay."

  19. QoS and QoE Aware N-Screen Multicast Service

    Directory of Open Access Journals (Sweden)

    Ghulam Sarwar

    2016-01-01

    Full Text Available The paper focuses on ensuring the quality-of-service (QoS and quality-of-experience (QoE requirements of users having heterogeneous devices in a multicast session. QoS parameters such as bit rate, delays, and packet losses are good indicators for optimizing network services but fall short in characterizing user perception (QoE. In N-Screen service, the users have different devices with heterogeneous attributes like screen size, resolution, and access network interface, and the users have different QoE on N-Screen devices with the same QoS parameters. We formulate the objective function of the N-Screen multicast grouping to ensure the minimum user’s QoE with smaller bandwidth requirement. We propose a dynamic user reassignment scheme to maintain and satisfy the QoE by adapting the user’s membership to the varying network conditions. The proposed schemes combine the available bandwidth and multimedia visual quality to ensure the QoS and QoE. In the network architecture, we introduce the functions of the QoS and QoE aware multicast group management and the estimation schemes for the QoS and QoE parameters. The simulation results show that the proposed multicast service ensures the network QoS and guarantees the QoE of users in the varying network conditions.

  20. Joint NC-ARQ and AMC for QoS-Guaranteed Mobile Multicast

    DEFF Research Database (Denmark)

    Toftegaard, Thomas Skjødeberg; Wang, Haibo; Schwefel, Hans-Peter;

    2010-01-01

    In mobile multicast transmissions, the receiver with the worst instantaneous channel condition limits the transmission data rate under the desired Quality-of-Service (QoS) constraints. If Automatic Repeat reQuest (ARQ) schemes are applied, the selection of Adaptive Modulation and Coding (AMC) mod...

  1. All-optical broadcast and multicast technologies based on PPLN waveguide

    DEFF Research Database (Denmark)

    Ye, Lingyun; Wang, Ju; Hu, Hao

    2013-01-01

    All-optical 1×4 broadcast and 1×3 multicast experiments of a 40-Gb/s return-to-zero on-off keying (RZ-OOK) signal based on a periodically poled lithium niobate (PPLN) waveguide are demonstrated in this letter. Clear opened eye diagrams and error-free performance are achieved for the broadcast...

  2. QoS multicast routin8 protocol in hierarchical wireless MANET

    Institute of Scientific and Technical Information of China (English)

    LI LaYuan; LI ChunLin

    2008-01-01

    A wireless MANET is s self-configurable network in which mobile, battery-powered devices dynamically create and change the network topology without relying on any intrastructure or administrative support. It offers unique benefits for certain environments, but there are still several open issues to be resolved before realizing these benefits, including QoS routing, multicasting, and mobility management. Specifically, an efficient QoS multicast routing protocol is needed. This paper pre-sents a hierarchical QoS multicast routing protocol (QMRP) for mobile ad hoc networks, it can provide QoS-sensitive routes in a scalable and flexible way, in the network environment with mobility. In the proposed QMRP scheme, each local node only needs to maintain local multicast routing information and/or summary infor-mation of other clusters (or domains) but does not require any global ad hoc net-work states to be maintained. The QMRP also allows any ad hoc group member to join/leave the muIticast group dynamically and supports multiple QoS constraints. This paper presents formal description and main procedures for realizing routing decision process of the QMRP and the proof of correctness and complexity analy-sis of the protocol. The performance measures of QMRP are evaluated using simulation. The simulation results verify the efficiency and availability of QMRP.

  3. Is Light-Tree Structure Optimal for Multicast Routing in Sparse Light Splitting WDM Networks?

    CERN Document Server

    Zhou, Fen; Cousin, Bernard; 10.1109/ICCCN.2009.5235386

    2010-01-01

    To minimize the number of wavelengths required by a multicast session in sparse light splitting wavelength division multiplexing (WDM) networks, a light-hierarchy structure, which occupies the same wavelength on all links, is proposed to span as many destinations as possible. Different from a light-tree, a light-hierarchy accepts cycles, which are used to traverse crosswise a 4-degree (or above) multicast incapable (MI) node twice (or above) and switch two light signals on the same wavelengths to two destinations in the same multicast session. In this paper, firstly, a graph renewal and distance priority light-tree algorithm (GRDP-LT) is introduced to improve the quality of light-trees built for a multicast request. Then, it is extended to compute light-hierarchies. Obtained numerical results demonstrate the GRDP-LT light-trees can achieve a much lower links stress, better wavelength channel cost, and smaller average end-to-end delay as well as diameter than the currently most efficient algorithm. Furthermore...

  4. An enhanced framework for providing multimedia broadcast/multicast service over heterogeneous networks

    Institute of Scientific and Technical Information of China (English)

    Yi-han XU; Chee-Onn CHOW; Mau-Luen THAM; Hiroshi ISHII

    2014-01-01

    Multimedia broadcast multicast service (MBMS) with inherently low requirement for network resources has been proposed as a candidate solution for using such resources in a more efficient manner. On the other hand, the Next Generation Mobile Network (NGMN) combines multiple radio access technologies (RATs) to optimize overall network performance. Handover performance is becoming a vital indicator of the quality experience of mobile user equipment (UE). In contrast to the conventional vertical handover issue, the problem we are facing is how to seamlessly transmit broadcast/multicast sessions among heterogeneous networks. In this paper, we propose a new network entity, media independent broadcast multicast service center (MIBM-SC), to provide seamless handover for broadcast/multicast sessions over heterogeneous networks, by extensions and enhancements of MBMS and media independent information service (MIIS) architectures. Additionally, a network selection scheme and a cell transmission mode selection scheme are proposed for selecting the best target network and best transmission mode. Both schemes are based on a load-aware network capacity estimation algorithm. Simulation results show that the pro-posed approach has the capability to provide MBMS over heterogeneous networks, with improved handover performance in terms of packet loss rate, throughput, handover delay, cell load, bandwidth usage, and the peak signal-to-noise ratio (PSNR).

  5. Joint NC-ARQ and AMC for QoS-Guaranteed Mobile Multicast

    DEFF Research Database (Denmark)

    Wang, Haibo; Schwefel, Hans-Peter; Chu, Xiaoli;

    2010-01-01

    In mobile multicast transmissions, the receiver with the worst instantaneous channel condition limits the transmission data rate under the desired Quality-of-Service (QoS) constraints. If Automatic Repeat reQuest (ARQ) schemes are applied, the selection of Adaptive Modulation and Coding (AMC) mode...

  6. A novel round-robin based multicast scheduling algorithm for 100 Gigabit Ethernet switches

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2010-01-01

    This paper proposes a round-robin based multicast scheduling algorithm for high-speed input-queued switches. Fan-out information of each head-of-line cell is examined by the packet scheduler to form a matrix called Traffic Matrix. A subscheduler for each column executes the round-robin scheduling...

  7. QoS Routing in Multicast Networks Based on Imperialism Competition Algorithm

    Directory of Open Access Journals (Sweden)

    Parisa Mollamohammada

    Full Text Available At the age of multimedia communications and high speed networks, multicast is one of the mechanisms which we can employ to enjoy the power of internet. On the other hand, increase in real-time multimedia applications, has emerged the need for Quality of S ...

  8. History-based Adaptive Modulation for a Downlink Multicast Channel in OFDMA systems

    DEFF Research Database (Denmark)

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2008-01-01

    In this paper we investigated the adaptive modulation strategies for Multicast service in orthogonal frequency division multiple access systems. We defined a Reward function as the performance optimization target and developed adaptive modulation strategies to maximize this Reward function. The p...

  9. Identifying and structurally characterizing CD1b in Aotus nancymaae owl monkeys.

    Science.gov (United States)

    Castillo, Fabio; Guerrero, Carlos; Trujillo, Esperanza; Delgado, Gabriela; Martinez, Pilar; Salazar, Luz M; Barato, Paola; Patarroyo, Manuel E; Parra-López, Carlos

    2004-10-01

    This study reports the molecular characterization and tissue expression of the non-human Aotus nancymaae primate CD1b isoform in the search for an experimental animal model to be used in evaluating the role of non-peptide antigen-presentation molecules in the immune response to infectious agents. CD1b expression on the surface of A. nancymaae peripheral blood monocyte-derived dendritic cells, shown by flow cytometry, was made possible by using human CD1b isoform antibodies. Studying the expression of CD1b-encoded transcripts revealed this molecule's broad distribution in several tissues. The A. nancymaae CD1b transcript-encoded amino-acid sequence showed 95.5% identity with the human sequence. Such high sequence homology was reflected in the identical structural conservation of how pockets A', C' and F' and tunnel T' conforming the antigen's binding site are organized, the similar arrangement of those amino-acids interacting with the T-cell receptor (TCR) during antigen presentation, and the conservation of YQNI-motif sequence in the cytoplasmatic tail (responsible for the molecule's intracellular trafficking in humans). Comparing the structure of human CD1a and CD1b and mouse CD1d proteins with CD1b structure in A. nancymaae obtained by minimization revealed that changes in the latter molecule's alpha1 and alpha2 domains imposed a narrowing of the antigen-binding groove in A. nancymaae CD1b. The high structural similarity between A. nancymaae CD1b and that from humans presented in this study leads to A. nancymaae being proposed as a suitable experimental animal model for analyzing CD1b in vivo, mainly in bacterial and parasite infections such as tuberculosis and malaria, respectively.

  10. Neutron scattering studies of Cd1−xMnxTe

    DEFF Research Database (Denmark)

    Giebultowicz, T.; Lebech, Bente; Buras, B

    1984-01-01

    The diluted magnetic (‘‘semimagnetic’’) semiconductor Cd1–xMnxTe reveals intriguing spin glass properties. In this paper, the results of neutron scattering studies of Cd1–xMnxTe are presented. The low‐temperature spin correlations have been studied for several single crystal samples in the compos......The diluted magnetic (‘‘semimagnetic’’) semiconductor Cd1–xMnxTe reveals intriguing spin glass properties. In this paper, the results of neutron scattering studies of Cd1–xMnxTe are presented. The low‐temperature spin correlations have been studied for several single crystal samples...

  11. Lysosomal-associated transmembrane protein 5 (LAPTM5 is a molecular partner of CD1e.

    Directory of Open Access Journals (Sweden)

    Catherine Angénieux

    Full Text Available The CD1e protein participates in the presentation of lipid antigens in dendritic cells. Its transmembrane precursor is transported to lysosomes where it is cleaved into an active soluble form. In the presence of bafilomycin, which inhibits vacuolar ATPase and consequently the acidification of endosomal compartments, CD1e associates with a 27 kD protein. In this work, we identified this molecular partner as LAPTM5. The latter protein and CD1e colocalize in trans-Golgi and late endosomal compartments. The quantity of LAPTM5/CD1e complexes increases when the cells are treated with bafilomycin, probably due to the protection of LAPTM5 from lysosomal proteases. Moreover, we could demonstrate that LAPTM5/CD1e association occurs under physiological conditions. Although LAPTM5 was previously shown to act as a platform recruiting ubiquitin ligases and facilitating the transport of receptors to lysosomes, we found no evidence that LATPM5 controls either CD1e ubiquitination or the generation of soluble lysosomal CD1e proteins. Notwithstanding these last observations, the interaction of LAPTM5 with CD1e and their colocalization in antigen processing compartments both suggest that LAPTM5 might influence the role of CD1e in the presentation of lipid antigens.

  12. An Improved Multicast Routing Algorithm%一个改进的多播路由算法

    Institute of Scientific and Technical Information of China (English)

    蒋廷耀; 李庆华

    2004-01-01

    Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper,we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks.

  13. Near-field self-interference cancellation and quality of service multicast beamforming in full-duplex

    Science.gov (United States)

    Wu, Fei; Shao, Shihai; Tang, Youxi

    2016-10-01

    To enable simultaneous multicast downlink transmit and receive operations on the same frequency band, also known as full-duplex links between an access point and mobile users. The problem of minimizing the total power of multicast transmit beamforming is considered from the viewpoint of ensuring the suppression amount of near-field line-of-sight self-interference and guaranteeing prescribed minimum signal-to-interference-plus-noise-ratio (SINR) at each receiver of the multicast groups. Based on earlier results for multicast groups beamforming, the joint problem is easily shown to be NP-hard. A semidefinite relaxation (SDR) technique with linear program power adjust method is proposed to solve the NP-hard problem. Simulation shows that the proposed method is feasible even when the local receive antenna in nearfield and the mobile user in far-filed are in the same direction.

  14. Experimental Analysis of the Fault Tolerance of the PIM-SM IP Multicast Routing Protocol under GNS3

    Directory of Open Access Journals (Sweden)

    Gábor Lencse

    2014-06-01

    Full Text Available PIM-SM is the most commonly used IP multicast routing protocol in IPTV systems. Its fault tolerance is examined by experimenting on a mesh topology multicast test network built up by Cisco routers under GNS3. Different fault scenarios are played and different parameters of the PIM-SM and of the OSPF protocols are examined if they influence and how they influence the outage time of an IPTV service. The failure of the Rendezvous Point (RP of the given IP multicast group as well as the complete failure of a router in the media forwarding path of the multicast stream are examined. A method is given how the service outage time caused by the complete failure of a router can be limited by an appropriate choice of the Dead Interval parameter of OSPF.

  15. Demonstration of obstruction-free data-carrying N-fold Bessel modes multicasting from a single Gaussian mode.

    Science.gov (United States)

    Zhu, Long; Wang, Jian

    2015-12-01

    By designing and optimizing complex phase pattern combining with axicon phase distribution, we report data multicasting from a single Gaussian mode to multiple Bessel modes using a single phase-only spatial light modulator. Under the obstructed path conditions, obstruction-free data-carrying N-fold Bessel modes multicasting is demonstrated in the experiment. We also experimentally study N-fold multicasting of a 20 Gbit/s quadrature phase-shift keying signal from a single Gaussian mode to multiple Bessel modes and measure the link performance. All the multicasted Bessel modes show relatively low crosstalk from their neighboring modes and achieve a bit-error rate of less than 1e-3.

  16. Potent neutralizing anti-CD1d antibody reduces lung cytokine release in primate asthma model.

    Science.gov (United States)

    Nambiar, Jonathan; Clarke, Adam W; Shim, Doris; Mabon, David; Tian, Chen; Windloch, Karolina; Buhmann, Chris; Corazon, Beau; Lindgren, Matilda; Pollard, Matthew; Domagala, Teresa; Poulton, Lynn; Doyle, Anthony G

    2015-01-01

    CD1d is a receptor on antigen-presenting cells involved in triggering cell populations, particularly natural killer T (NKT) cells, to release high levels of cytokines. NKT cells are implicated in asthma pathology and blockade of the CD1d/NKT cell pathway may have therapeutic potential. We developed a potent anti-human CD1d antibody (NIB.2) that possesses high affinity for human and cynomolgus macaque CD1d (KD ∼100 pM) and strong neutralizing activity in human primary cell-based assays (IC50 typically <100 pM). By epitope mapping experiments, we showed that NIB.2 binds to CD1d in close proximity to the interface of CD1d and the Type 1 NKT cell receptor β-chain. Together with data showing that NIB.2 inhibited stimulation via CD1d loaded with different glycolipids, this supports a mechanism whereby NIB.2 inhibits NKT cell activation by inhibiting Type 1 NKT cell receptor β-chain interactions with CD1d, independent of the lipid antigen in the CD1d antigen-binding cleft. The strong in vitro potency of NIB.2 was reflected in vivo in an Ascaris suum cynomolgus macaque asthma model. Compared with vehicle control, NIB.2 treatment significantly reduced bronchoalveolar lavage (BAL) levels of Ascaris-induced cytokines IL-5, IL-8 and IL-1 receptor antagonist, and significantly reduced baseline levels of GM-CSF, IL-6, IL-15, IL-12/23p40, MIP-1α, MIP-1β, and VEGF. At a cellular population level NIB.2 also reduced numbers of BAL lymphocytes and macrophages, and blood eosinophils and basophils. We demonstrate that anti-CD1d antibody blockade of the CD1d/NKT pathway modulates inflammatory parameters in vivo in a primate inflammation model, with therapeutic potential for diseases where the local cytokine milieu is critical.

  17. Application-Network Cross Layer Multi-variable Cost Function for Application Layer Multicast of Multimedia Delivery over Convergent Networks

    OpenAIRE

    Le, Tien Anh; Nguyen, Hang; Nguyen, Manh Cuong

    2015-01-01

    International audience; Application layer multicast (ALM) algorithms are either similar or conceptually based on network layer multicast's cost functions. In this research work, a new application-network cross layer multi-variable cost function is proposed. It optimizes the variable requirements and available resources from both the application and the network layers. It can dynamically update the available resources required for reaching a particular node on the ALM's media distribution tree...

  18. Cross-layer design of LT codes and LDPC codes for satellite multimedia broadcast/multicast services

    Institute of Scientific and Technical Information of China (English)

    Wang Zhenbang; Wang Zhenyong; Gu Xuemai; Guo Qing

    2013-01-01

    According to large coverage of satellites, there are various channel states in a satellite broadcasting network. In order to introduce an efficient rateless transmission method to satellite multimedia broadcasting/multicast services with finite-length packets, a cross-layer packet transmis-sion method is proposed with Luby transform (LT) codes for efficiency in the network layer and low density parity check (LDPC) codes for reliability in the physical layer jointly. The codewords gen-erated from an LT encoder are divided into finite-length packets, which are encoded by an LDPC encoder subsequently. Based on noise and fading effects of satellite channels, the LT packets received from an LDPC decoder either have no error or are marked as erased, which can be mod-eled as a binary erasure channels (BECs). By theoretical analysis on LT parameters and LDPC parameters, the relationships between LDPC code rates in the physical layer and LT codes word lengths in the network layer are investigated. With tradeoffs between the LT codes word lengths and the LDPC code rates, optimized cross-layer solutions are achieved with a binary search algo-rithm. Verified by simulations, the proposed solution for cross-layer parameters design can provide the best transmission mode according to satellite states, so as to improve throughput performance for satellite multimedia transmission.

  19. Energy-Efficient Multicast Transmission for Underlay Device-to-Device Communications: A Social-Aware Perspective

    Directory of Open Access Journals (Sweden)

    Fan Jiang

    2017-01-01

    Full Text Available In this paper, by utilizing the social relationships among mobile users, we present a framework of energy-efficient cluster formation and resource allocation for multicast D2D transmission. In particular, we first deal with D2D multicast cluster/group formation strategy from both physical distance and social trust level. Then we aim to maximize the overall energy-efficiency of D2D multicast groups through resource allocation and power control scheme, which considers the quality-of-service (QoS requirements of both cellular user equipment and D2D groups. A heuristic algorithm is proposed to solve above energy-efficiency problem with less complexity. After that, considering the limited battery capacity of mobile users, we propose an energy and social aware cluster head update algorithm, which incorporates both the energy constraint and social centrality measurement. Numerical results indicate that the proposed social-tie based D2D multicast group formation and update algorithm form a multicast group in an energy efficient way. Moreover, the proposed resource and power allocation scheme achieves better energy efficiency in terms of throughput per energy consumption. These results show that, by exploiting social domain information, underlay D2D multicast transmission has high practical potential in saving the source on wireless links and in the backhaul.

  20. Non-Degenerate Four-Wave Mixing in a Silicon Nanowire and its Application for One-to-Six WDM Multicasting

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2011-01-01

    We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements.......We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements....

  1. Origin Use of CD4, CD8, and CD1a Immunostains in Distinguishing Mycosis Fungoides from its Inflammatory Mimics: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Rajalakshmi Tirumalae

    2012-01-01

    Full Text Available Patch-stage/early mycosis fungoides (MF is difficult to differentiate from benign dermatoses, despite several robust histologic criteria. Most studies include advanced lesions and data about early disease is limited. Objectives: (1 To compare the CD4:CD8 ratio in patch-stage MF versus inflammatory mimics. (2 To study patterns of CD1a expression in the epidermis and dermis in the two groups. Materials and Methods: Twenty cases each of early MF and inflammatory dermatoses were selected. The diagnoses were established after clinicopathologic correlation, repeat biopsies, and follow-up. The inflammatory group included pityriasis lichenoides chronica, actinic reticuloid, lichenoid purpura, and various psoriasiform dermatoses. Immunohistochemistry was done for CD4, CD8, and CD1a. Epidermal CD4, CD8 cells were quantified and CD1a was graded semi-quantitatively in the epidermis and dermis. Results: The average CD4:CD8 ratio was 4.2 in MF (range: 1-16.8, and 0.9 in inflammatory diseases (range: 0.43-5, which was statistically significant (P 1. CD1a cells had a continuous or confluent epidermal pattern in almost all cases of MF, while they occurred as small or large groups in the dermis. In inflammatory dermatoses, there were either isolated or scattered CD1a+ cells in both epidermis and dermis. Conclusions: Elevated CD4:CD8 ratio favors MF. But there is an overlap in the lower range with pityriasis lichenoides chronica. These cases require good clinicopathologic correlation and follow-up. Patterns of CD1a expression are more reliable. Immunostains buttress morphology and are a valuable addition.

  2. CD1-dependent regulation of chronic central nervous system inflammation in experimental autoimmune encephalomyelitis

    DEFF Research Database (Denmark)

    Teige, Anna; Teige, Ingrid; Lavasani, Shahram

    2004-01-01

    The existence of T cells restricted for the MHC I-like molecule CD1 is well established, but the function of these cells is still obscure; one implication is that CD1-dependent T cells regulate autoimmunity. In this study, we investigate their role in experimental autoimmune encephalomyelitis (EA...

  3. Linkage mapping of a dominant male sterility gene Ms-cd1 in Brassica oleracea

    NARCIS (Netherlands)

    Wang, X.; Lou, P.; Bonnema, A.B.; Yang, Boujun; He, H.; Zhang, Y.; Fang, Z.

    2005-01-01

    The dominant male sterility gene Ms-cd1 (c, cabbage; d, dominant) was identified as a spontaneous mutation in the spring cabbage line 79-399-3. The Ms-cd1 gene is successfully applied in hybrid seed production of several Brassica oleracea cultivars in China. Amplified fragment length polymorphism

  4. 12 CFR Appendix 1 to Part 24 - CD-1-National Bank Community Development (Part 24) Investments

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false CD-1-National Bank Community Development (Part 24) Investments 1 Appendix 1 To Part 24 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF... PUBLIC WELFARE INVESTMENTS Pt. 24, App. 1 Appendix 1 To Part 24—CD-1—National Bank Community Development...

  5. Chromatofocusing purification of CD1b-antigen complexes and their analysis by isoelectric focusing.

    Science.gov (United States)

    Garcia-Alles, Luis Fernando; de la Salle, Henri

    2013-01-01

    The presentation of lipid antigens to T cells is mediated by the CD1 proteins. Purified functional CD1/lipid complexes are valuable tools to investigate such immune processes. Here, we describe how these complexes can be prepared in vitro, how they can be purified by chromatofocusing and how to control their antigen-loading status by isoelectric focusing.

  6. Crystal structure of bovine CD1b3 with endogenously bound ligands

    NARCIS (Netherlands)

    Girardi, E.; Wang, J.; Mac, T.T.; Versluis, C.; Bhowruth, V.; Besra, G.; Heck, A.J.R.; van Rhijn, I.; Zajonc, D.M.

    2010-01-01

    The CD1 family of Ag-presenting molecules is able to display lipids to T cells by binding them within a hydrophobic groove connected to the protein surface. In particular, the CD1b isotype is capable of binding ligands with greatly varying alkyl chain lengths through a complex network of interconnec

  7. Linkage mapping of a dominant male sterility gene Ms-cd1 in Brassica oleracea

    NARCIS (Netherlands)

    Wang, X.; Lou, P.; Bonnema, A.B.; Yang, Boujun; He, H.; Zhang, Y.; Fang, Z.

    2005-01-01

    The dominant male sterility gene Ms-cd1 (c, cabbage; d, dominant) was identified as a spontaneous mutation in the spring cabbage line 79-399-3. The Ms-cd1 gene is successfully applied in hybrid seed production of several Brassica oleracea cultivars in China. Amplified fragment length polymorphism (A

  8. Alternative spliced CD1d transcripts in human bronchial epithelial cells.

    Directory of Open Access Journals (Sweden)

    Kambez Hajipouran Benam

    Full Text Available CD1d is a MHC I like molecule which presents glycolipid to natural killer T (NKT cells, a group of cells with diverse but critical immune regulatory functions in the immune system. These cells are required for optimal defence against bacterial, viral, protozoan, and fungal infections, and control of immune-pathology and autoimmune diseases. CD1d is expressed on antigen presenting cells but also found on some non-haematopoietic cells. However, it has not been observed on bronchial epithelium, a site of active host defence in the lungs. Here, we identify for the first time, CD1D mRNA variants and CD1d protein expression on human bronchial epithelial cells, describe six alternatively spliced transcripts of this gene in these cells; and show that these variants are specific to epithelial cells. These findings provide the basis for investigations into a role for CD1d in lung mucosal immunity.

  9. Polyclonal T-cells express CD1a in Langerhans cell histiocytosis (LCH lesions.

    Directory of Open Access Journals (Sweden)

    Jennifer A West

    Full Text Available Langerhans cell histiocytosis (LCH is a complex and poorly understood disorder that has characteristics of both inflammatory and neoplastic disease. By using eight-colour flow cytometry, we have identified a previously unreported population of CD1a(+/CD3(+ T-cells in LCH lesions. The expression of CD1a is regarded as a hallmark of this disease; however, it has always been presumed that it was only expressed by pathogenic Langerhans cells (LCs. We have now detected CD1a expression by a range of T-cell subsets within all of the LCH lesions that were examined, establishing that CD1a expression in these lesions is no longer restricted to pathogenic LCs. The presence of CD1a(+ T-cells in all of the LCH lesions that we have studied to date warrants further investigation into their biological function to determine whether these cells are important in the pathogenesis of LCH.

  10. Polyclonal T-Cells Express CD1a in Langerhans Cell Histiocytosis (LCH) Lesions

    Science.gov (United States)

    West, Jennifer A.; Olsen, Sharon L.; Mitchell, Jenée M.; Priddle, Ross E.; Luke, Jennifer M.; Åkefeldt, Selma Olsson; Henter, Jan-Inge; Turville, Christopher; Kannourakis, George

    2014-01-01

    Langerhans cell histiocytosis (LCH) is a complex and poorly understood disorder that has characteristics of both inflammatory and neoplastic disease. By using eight-colour flow cytometry, we have identified a previously unreported population of CD1a+/CD3+ T-cells in LCH lesions. The expression of CD1a is regarded as a hallmark of this disease; however, it has always been presumed that it was only expressed by pathogenic Langerhans cells (LCs). We have now detected CD1a expression by a range of T-cell subsets within all of the LCH lesions that were examined, establishing that CD1a expression in these lesions is no longer restricted to pathogenic LCs. The presence of CD1a+ T-cells in all of the LCH lesions that we have studied to date warrants further investigation into their biological function to determine whether these cells are important in the pathogenesis of LCH. PMID:25343480

  11. Influence of lipid rafts on CD1d presentation by dendritic cells

    DEFF Research Database (Denmark)

    Peng, Wei; Martaresche, Cecile; Escande-Beillard, Nathalie

    2011-01-01

    corresponding to lipid rafts and we describe that alpha-GalCer enhanced CD1d amount in the low density detergent insoluble fraction. We conclude that the membrane environment of CD1d can influence antigen presentation mainly when the endocytic pathway is required. Flow cytometry analysis can provide additional...... information on lipid rafts in plasma membranes and allows a dynamics follow-up of lipid rafts partitioning. Using this method, we showed that CD1d plasma membrane expression was sensitive to low concentrations of detergent. This may suggest either that CD1d is associated with lipid rafts mainly......Our main objective was to analyze the role of lipid rafts in the activation of Valpha-14(-) and Valpha-14(+) T hybridomas by dendritic cells. We showed that activation of Valpha-14(+) hybridomas by dendritic cells or other CD1d-expressing cells was altered by disruption of lipid rafts...

  12. Performance improvement of an optical network providing services based on multicast

    CERN Document Server

    Reinhard, Vincent; Tomasik, Joanna; Barth, Dominique; Weisser, Marc-Antoine

    2011-01-01

    Operators of networks covering large areas are confronted with demands from some of their customers who are virtual service providers. These providers may call for the connectivity service which fulfils the specificity of their services, for instance a multicast transition with allocated bandwidth. On the other hand, network operators want to make profit by trading the connectivity service of requested quality to their customers and to limit their infrastructure investments (or do not invest anything at all). We focus on circuit switching optical networks and work on repetitive multicast demands whose source and destinations are {\\em \\`a priori} known by an operator. He may therefore have corresponding trees "ready to be allocated" and adapt his network infrastructure according to these recurrent transmissions. This adjustment consists in setting available branching routers in the selected nodes of a predefined tree. The branching nodes are opto-electronic nodes which are able to duplicate data and retransmit...

  13. QoS multicast routing scheme using QGA in IP/DWDM networks

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This article studies multi-constraints least-cost multicast routing problem in internet protocol over dense wavelength division multiplexing (IP/DWDM) networks. To address this problem, an individual-difference-based quantum genetic algorithm (IDQGA) is proposed. This algorithm considers individual differences among chromosomes by introducing an adaptive rotation angle step determination scheme and a grouping-based quantum mutation operation. Simulations are conducted over network topologies. The results indicate that compared with other heuristic algorithms, IDQGA has better optimal performance on solving quality of service (QoS) multicast routing problem in IP/DWDM networks and is characterized by strong robustness, high success ratio and excellent capability on global searching.

  14. On-Demand Multicasting in Ad-hoc Networks: Performance Evaluation of AODV, ODMRP and FSR

    CERN Document Server

    Rajendiran, M

    2011-01-01

    Adhoc networks are characterized by connectivity through a collection of wireless nodes and fast changing network topology. Wireless nodes are free to move independent of each other which makes routing much difficult. This calls for the need of an efficient dynamic routing protocol. Mesh-based multicast routing technique establishes communications between mobile nodes of wireless adhoc networks in a faster and efficient way. In this article the performance of prominent on-demand routing protocols for mobile adhoc networks such as ODMRP (On Demand Multicast Routing Protocol), AODV (Adhoc on Demand Distance Vector) and FSR (Fisheye State Routing protocol) was studied. The parameters viz., average throughput, packet delivery ration and end-to-end delay were evaluated. From the simulation results and analysis, a suitable routing protocol can be chosen for a specified network. The results show that the ODMRP protocol performance is remarkably superior as compared with AODV and FSR routing protocols. Keywords: MANE...

  15. Effective Radio Resource Management for Multimedia Broadcast/Multicast Services in UMTS Networks

    Directory of Open Access Journals (Sweden)

    Soares Armando

    2006-01-01

    Full Text Available Broadcast and multicast offer a significant improvement of spectrum utilization, and become particularly important where information channels are shared among several users. Mobile cellular environments are expected to evolve with the technological approaches necessary to facilitate the deployment of multimedia services, such as streaming, file download, and carousel services. The perspective that video streaming in wireless networks services is an attractive service to end-users has spurred the research in this area. To provide for a video delivery platform in UMTS, the third generation partnership project (3GPP addressed this problem with the introduction of the multimedia broadcast and multicast services (MBMS in 3GPP Release 6. In this document we analyse several effective radio resource management techniques to provide MBMS, namely, use of nonuniform QAM constellations, multicode, and macrodiversity to guarantee the optimal distribution of QoS depending on the location of mobiles.

  16. Cost of Multicast Logical Key Tree Based on Hierarchical Data Processing

    Institute of Scientific and Technical Information of China (English)

    ZHOU Fucai; XU Jian; LI Ting

    2006-01-01

    How to design a multicast key management system with high performance is a hot issue now. This paper will apply the idea of hierarchical data processing to construct a common analytic model based on directed logical key tree and supply two important metrics to this problem: re-keying cost and key storage cost. The paper gives the basic theory to the hierarchical data processing and the analyzing model to multicast key management based on logical key tree. It has been proved that the 4-ray tree has the best performance in using these metrics. The key management problem is also investigated based on user probability model, and gives two evaluating parameters to re-keying and key storage cost.

  17. QoS-Based Dynamic Multicast Routing Design Using Genetic Algorithms

    Institute of Scientific and Technical Information of China (English)

    YUANYouwei; YANLamei

    2004-01-01

    This paper addresses the problem of determining minimum cost paths to nodes in a Multicast group satisfying delay bounds and delay variation bounds. This study explores the use of Genetic algorithms (GAs) for solving the multicast routing problems when multiple Quality of services (QoS) requirements are presented. Our simulation results indicate that it is critical to select a suitable representation method and a set of appropriate parameters in order to obtain good performance. For a medium network, the probability from 0.02 to 0.2 seems to work better than those of too small or too large. As compared with the other optimal algorithm, the proposed algorithm gives better performance in terms of the success rate, the tree cost, the number of exchanged messages and the convergence time.

  18. Impact of Physical Layer Jamming on Wireless Sensor Networks with Shadowing and Multicasting

    Directory of Open Access Journals (Sweden)

    Nischay Bahl

    2012-07-01

    Full Text Available This paper analyzes the impact of a physical layer jamming on the performance of wireless sensor networks by performing exhaustive comparative simulations using multicasting and by employing varying intensity of shadowing (constant and log normal. Comprehensive result analysis reveals that jamming drastically degrades the legitimate traffic throughput in a network, and, the constant shadowing approach is a better fit for a static network, both, under static as well as mobile jammer environments, as compared to the log normal one. An improvement in sink-node packet delivery ratio by 15.02 % and 16.58 % was observed with static and mobile jammer environments respectively, under multicasting and constant shadowing mean of 8.0. Further, average sink-node packet delivery ratio with constant shadowing shows an improvement of 4.15% and 5.94%, using static and mobile jammer environment respectively, in comparison to the values obtained under log normal shadowing based network.

  19. Optimizing Energy and Modulation Selection in Multi-Resolution Modulation For Wireless Video Broadcast/Multicast

    KAUST Repository

    She, James

    2009-11-01

    Emerging technologies in Broadband Wireless Access (BWA) networks and video coding have enabled high-quality wireless video broadcast/multicast services in metropolitan areas. Joint source-channel coded wireless transmission, especially using hierarchical/superposition coded modulation at the channel, is recognized as an effective and scalable approach to increase the system scalability while tackling the multi-user channel diversity problem. The power allocation and modulation selection problem, however, is subject to a high computational complexity due to the nonlinear formulation and huge solution space. This paper introduces a dynamic programming framework with conditioned parsing, which significantly reduces the search space. The optimized result is further verified with experiments using real video content. The proposed approach effectively serves as a generalized and practical optimization framework that can gauge and optimize a scalable wireless video broadcast/multicast based on multi-resolution modulation in any BWA network.

  20. MULTICAST ROUTING WITH QUALITY OF SERVICE CONSTRAINTS IN THE AD HOC WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    Abdellah Idrissi

    2014-01-01

    Full Text Available The recent multimedia applications and services are very demanding in terms of Quality of Service (QoS. This creates new challenges in ensuring QoS when delivering those services over wireless networks. Motivated by the need of supporting high quality multicast applications in wireless ad hoc networks, we propose a network topology that can minimize the power when connecting the source node to the destination nodes in multicast sessions with the respect of the QoS provisions. We formulated the problem as integer linear programming problem with a set of energy and QoS constraints. We minimize the total power of energy used by nodes while satisfying QoS constraints (Bandwidth and maximum delay that are crucial to wireless ad hoc network performance.

  1. 基于组播网关的可靠组播体系结构%Reliable multicast architecture based on multicast gateway

    Institute of Scientific and Technical Information of China (English)

    姜腊林; 徐蔚鸿; 于枫; 樊俊青

    2009-01-01

    保证组播通信的可靠性是许多Internet上的组播应用的前提.针对IP组播在Internet中难以规模化部署的现状,提出了一种使用组播网关将IP组播岛与应用层组播(ALM)区域连接起来的可靠组播(RM)体系结构,对组标识、组播网关、组管理、差错控制和拥塞控制等关键问题给出了解决方案,并设计了组播网关竞争算法.该结构能够屏蔽底层组播技术差异,从而支持Internet上统一化的可靠组播服务部署.

  2. Core-based Shared Tree Multicast Routing Algorithms for LEO Satellite IP Networks

    Institute of Scientific and Technical Information of China (English)

    Cheng Lianzhen; Zhang Jun; Liu Kai

    2007-01-01

    A new core-based shared tree algorithm, viz core-cluster combination-based shared tree (CCST) algorithm and the weighted version (i.e. w-CCST algorithm) are proposed in order to resolve the channel resources waste problem in typical source-based multicast routing algorithms in low earth orbit (LEO) satellite IP networks. The CCST algorithm includes the dynamic approximate center (DAC)core selection method and the core-cluster combination multicast route construction scheme. Without complicated onboard computation,the DAC method is uniquely developed for highly dynamic networks of periodical and regular movement. The core-cluster combination method takes core node as the initial core-cluster, and expands it stepwise to construct an entire multicast tree at the lowest tree cost by a shortest path scheme between the newly-generated core-cluster and surplus group members, which results in great bandwidth utilization.Moreover, the w-CCST algorithm is able to strike a balance between performance of tree cost and that of end-to-end propagation delay by adjusting the weighted factor to meet strict end-to-end delay requirements of some real-time multicast services at the expense of a slight increase in tree cost. Finally, performance comparison is conducted between the proposed algorithms and typical algorithms in LEO satellite IP networks. Simulation results show that the CCST algorithm significantly decreases the average tree cost against to the others, and also the average end-to-end propagation delay of w-CCST algorithm is lower than that of the CCST algorithm.

  3. Bulk data transfer distributer: a high performance multicast model in ALMA ACS

    Science.gov (United States)

    Cirami, R.; Di Marcantonio, P.; Chiozzi, G.; Jeram, B.

    2006-06-01

    A high performance multicast model for the bulk data transfer mechanism in the ALMA (Atacama Large Millimeter Array) Common Software (ACS) is presented. The ALMA astronomical interferometer will consist of at least 50 12-m antennas operating at millimeter wavelength. The whole software infrastructure for ALMA is based on ACS, which is a set of application frameworks built on top of CORBA. To cope with the very strong requirements for the amount of data that needs to be transported by the software communication channels of the ALMA subsystems (a typical output data rate expected from the Correlator is of the order of 64 MB per second) and with the potential CORBA bottleneck due to parameter marshalling/de-marshalling, usage of IIOP protocol, etc., a transfer mechanism based on the ACE/TAO CORBA Audio/Video (A/V) Streaming Service has been developed. The ACS Bulk Data Transfer architecture bypasses the CORBA protocol with an out-of-bound connection for the data streams (transmitting data directly in TCP or UDP format), using at the same time CORBA for handshaking and leveraging the benefits of ACS middleware. Such a mechanism has proven to be capable of high performances, of the order of 800 Mbits per second on a 1Gbit Ethernet network. Besides a point-to-point communication model, the ACS Bulk Data Transfer provides a multicast model. Since the TCP protocol does not support multicasting and all the data must be correctly delivered to all ALMA subsystems, a distributer mechanism has been developed. This paper focuses on the ACS Bulk Data Distributer, which mimics a multicast behaviour managing data dispatching to all receivers willing to get data from the same sender.

  4. Survey of Unicast and Multicast Scheduling Algorithms for High Speed Input Queued Switch with Crossbar

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The performance of ATM switches are mainly influenced by switching fabric and scheduling algorithms. Input buffered switches have the strong advantage of efficient crossbar usage. This paper presents an input-queued crossbar switches fabric supporting high speed switching, analyzes the scheduling algorithms for unicast trafficts and multicast traffic based on virtual output queueing (VOQ).Focusing on their performance issues, some typical schedulers are compared.

  5. DRMR:Dynamic-Ring-Based Multicast Routing Protocol for Ad Hoc Networks

    Institute of Scientific and Technical Information of China (English)

    Yuan Zhoux; Guang-Sheng Li; Yong-Zhao Zhan; Qi-Rong Mao; Yi-Bin Hou

    2004-01-01

    Recently a number of multicast routing protocols for ad hoc networks have been proposed, however, most of them do not provide proper tradeoffs between effectiveness, efficiency and scalability. In this paper, a novel multicast routing protocol is presented for ad hoc networks. The protocol, termed as dynamic-ring-based multicast routing protocol (DRMR), uses the concept of dynamic ring whose radius can be adjusted dynamically and DRMR configures this type of ring for all group member nodes. According to the principle of zone routing, two nodes whose rings overlap can create route to each other, thus, when the ring graph composed of all rings is connected, each member node has one or more routes to others. DRMR uses the method of expanding ring search (ERS) to maintain the connected ring graph, and also can decrease the radius of the ring to reduce the overhead. The performances of DRMR were simulated and evaluated with NS2, and results show that DRMR has a high data packet delivery ratio, low control overhead and good scalability.

  6. A New Solution of Multicast Packets Management for Managed Ethernet Switch

    Directory of Open Access Journals (Sweden)

    Sheng LU

    2012-12-01

    Full Text Available This paper has a discussion on the new solution of IGMP management for multicast message in industrial Ethernet. It proposed a new mechanism to minimize the congestion which is based on the taking an adaptive decision during transferring multicast messages. Proposed approach is that a device requesting to start and stop the reception of the multicast streams is accomplished through IGMP join and Leave message requests. Quality of Service (QOS as a component is supported by the Switch Manager as well as features built into the micro chip. The IGMP Snooping component monitors (snoops these join and leave messages to allow it to know which streams to prune from which ports. it is a service provided by most managed Ethernet switches. However, the ICIE (Intelligent Controller for Industrial Ethernet does not provide this capability and requires that another device in the network supports the querier functionality. It is through the external devices solicitation of join messages that allow the IGMP Snooping component to correctly decipher on which ports the downstream listeners are connected.

  7. Flow Control for Multicast: A Weighted Cost-Benefit Approach%针对组播的流量控制:带权的代价-收益法

    Institute of Scientific and Technical Information of China (English)

    何炎祥; 吕慧; 李旭晖; 杜卓敏; 王策

    2003-01-01

    This paper presents a weighted cost-benefit approach based on multicast. Grounded on overlay networkmodel, its principal idea is to construct cost function and benefit function. When estimated benefit is more than cost,multicast request is accepted. This paper demonstrates its application in packet-switched networks and points out itsmerits and shortcomings.

  8. One-to-six WDM multicasting of DPSK signals based on dual-pump four-wave mixing in a silicon waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2011-01-01

    We present WDM multicasting based on dual-pump four-wave mixing in a 3-mm long dispersion engineered silicon waveguide. One-to-six phase-preserving WDM multicasting of 10-Gb/s differential phase-shiftkeying (DPSK) data is experimentally demonstrated with bit-error rate measurements. All the six...

  9. Molecular mapping of MS-cd1 gene in Chinese kale

    African Journals Online (AJOL)

    STORAGESEVER

    2010-07-19

    Jul 19, 2010 ... were detected by cDNA-AFLP, which suggested that the dominant MS-cd1 ... Microarray analysis identified some differentially expressed genes between ..... linked to disease-resistance genes by bulked segregant analysis: a.

  10. Noise Characteristcs of Cd1-xZnxS Films Deposited From Solution

    Science.gov (United States)

    Guseinov, Emil; Jafarov, Maarif; Nasibov, Ilgar

    1997-12-01

    The study of Cd1-xZnxS (0≤ x ≤ 0.6) films obtained by method of chemical deposition from aqueous solution on glass ceramic substrates via interaction of thiourea with cadmium and zinc salts. In Cd1-xZnxS films just subsequent to their deposition 1/f-type noise is clearly revealed and is attributed to collective barries. In the frequency range above a few kilohertz the generation-recombination noises predominate In Cd1-xZnxS films after heat treatment in air at 500°C, generation-recombination noise dominates at relative frequencies. The noise level of Cd1-xZnxS films (0≤ x≤ 0,2) after heat treatment shows that they are useful as threshold radiation detectors (Pthr=10-12W).

  11. Efficient Design for the Implementation of Wong-Lam Multicast Authentication Protocol Using Two-Levels of Parallelism

    Directory of Open Access Journals (Sweden)

    Ghada F. Elkabbany

    2012-05-01

    Full Text Available Group communication can benefit from Internet Protocol (IP multicast protocol to achieve efficient exchange of messages. However, IP multicast does not provide any mechanisms for authentication. In literature, many solutions to solve this problem were presented. It has been shown that Wong and Lam protocol is the only protocol that can resist both packet loss and pollution attacks. In contrast, it has high computation and communication overheads. In the present paper, an efficient design for the implementation of Wong and Lam multicast authentication protocol is proposed. In order to solve the computation overhead problem, we use two-levels of parallelism. To reduce the communication overhead, we use Universal Message Authentication Codes (UMAC instead of hash functions. The design is analyzed for both NTRU and elliptic curve cryptography signature algorithms. The analysis shows that the proposed design decreases significantly the execution time of Wong-Lam protocol which makes it suitable for real-time applications.

  12. 基于多竞价拍卖机制的对等网络分布式组播协议研究%Distributed Multicast Protocol Based Multi-Bids Auction Mechanism in P2P Networks

    Institute of Scientific and Technical Information of China (English)

    王浩云; 张顺颐; 龙华; 李君

    2009-01-01

    This paper presents a novel multicast algorithm in Peer-to-Peer (P2P) networks, which can restrain the selfish and malicious actions of P2P nodes using the multi-bids auction mechanism.This paper also discusses the distributed multicast protocol to ensure that the algorithm proposed will operate normally in the highly dynamic network environment. Simulation results demonstrate the effectiveness and reliability of the proposed protocol.%本文提出了一种新的对等网络组播算法,该算法能通过多竞价拍卖机制有效地遏制了组播节点的自私行为和其它恶意行为.同时,本文提出了分布式的组播协议,以保证该组播算法在高度动态的对等网络环境下有效运行.仿真结果验证了本文所提组播算法及协议的有效性和可靠性.

  13. S100-Negative, CD1a-Positive Cutaneous Histiocytosis in a Patient with S100-Positive, CD1a-Positive Pulmonary Histiocytosis.

    Science.gov (United States)

    Mask-Bull, Lisa; Crowson, Neil A; John, Andrew; Mask, Neal A

    2015-08-01

    In the diagnostic approach to histiocytic proliferations, immunohistochemistry may be a source of both confusion and clarification. We present a case of a 60-year-old man with a generalized pruritic eruption that demonstrated positive staining for CD1a, but negative staining for langerin and S100 protein. This immunophenotype is neither representative nor characteristic of any recognized dendritic cell tumor but has been previously described in 3 cases of skin-limited histiocytosis. However, our patient also demonstrated pulmonary histiocytic infiltrates that were positive for both CD1a and S100 proteins. This differing expression of S100 protein witnessed in 2 separate organ systems affords us insight into the pathophysiology of these histiocytic proliferations.

  14. Evaluación de mecanismos de soporte de tráfico multicast con movilidad basada en red

    OpenAIRE

    González Díaz, Sergio

    2015-01-01

    Con el auge actual de Internet y el incremento en el uso de dispositivos móviles ha aumentado el consumo de contenido multimedia, del cual cabe destacar el streaming de vídeo, el vídeo bajo demanda y la IPTV. Muchos de estos servicios hacen uso de Multicast, un método de transmisión de datos a múltiples redes y destinatarios de manera simultánea. Para poder realizar transmisiones de datos multicast hay direcciones IP reservadas, tanto en IPv4 como en IPv6. El funcionamiento de ...

  15. Preventing Out-of-Sequence for Multicast Input-Queued Space-Memory-Memory Clos-Network

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This paper proposes an out-of-sequence (OOS) preventative cell dispatching algorithm, the multicast flow-based round robin (MFRR), for multicast input-queued space-memory-memory (IQ-SMM) Clos-network architecture. Independently treating each incoming cell, such as the desynchronized static round...... robin (DSRR), can lead to cells of the same packet being disordered after traversing the switch fabric. Extra reassembly buffer and delay are thus required at the outputs of the switch fabric to reorder the cells. Simulation results obtained by OPNET Modeler show that the MFRR can eliminate such OOS...

  16. Proposing an Optimum Multicasting Routing Algorithm Using Ant Colony for Improving QoS in Wireless Mesh Network

    Directory of Open Access Journals (Sweden)

    Mohsen Shakibafakhr

    2013-11-01

    Full Text Available Wireless mesh networks (WMNs are new emerging networks which are anticipated to resolve many limitations of ad-hoc networks, sensor networks and wireless local area networks and improve their performance. But still there are many unresolved research challenge in this area. In this paper we have proposed source-specific multicast protocol for wireless mesh network, which has many application in, multimedia, radio and TV multicasting and distance learning. We have used core-based approach to construct minimum cost tree (MCT among member nodes and optimized this tree for multiple metrics by applying ant colony optimization metaphor.

  17. Propuesta de un protocolo de enrutamiento multidifusión basado en agentes: Multicast Antnet Routing Protocol

    Directory of Open Access Journals (Sweden)

    Fernando Solano

    2003-01-01

    Full Text Available Este trabajo de investigación presenta un protocolo de enrutamiento multidifusión, MARP, que usa agentes móviles para hallar rutas eficientes de reenvío de paquetes desde una fuente hacia todos los miembros del grupo multicast. El mecanismo de reenvío de paquetes emplea balanceo de carga sobre las mejores rutas. El protocolo desarrollado usó como base el algoritmo de enrutamiento unidifusión AntNet, el cual se adaptó para trabajar en redes multicast.

  18. Nitrosylation of c heme in cd(1)-nitrite reductase is enhanced during catalysis.

    Science.gov (United States)

    Rinaldo, Serena; Giardina, Giorgio; Cutruzzolà, Francesca

    2014-08-29

    The reduction of nitrite into nitric oxide (NO) in denitrifying bacteria is catalyzed by nitrite reductase. In several species, this enzyme is a heme-containing protein with one c heme and one d1 heme per monomer (cd1NiR), encoded by the nirS gene. For many years, the evidence of a link between NO and this hemeprotein represented a paradox, given that NO was known to tightly bind and, possibly, inhibit hemeproteins, including cd1NiRs. It is now established that, during catalysis, cd1NiRs diverge from "canonical" hemeproteins, since the product NO rapidly dissociates from the ferrous d1 heme, which, in turn, displays a peculiar "low" affinity for NO (KD=0.11 μM at pH 7.0). It has been also previously shown that the c heme reacts with NO at acidic pH but c heme nitrosylation was not extensively investigated, given that in cd1NiR it was considered a side reaction, rather than a genuine process controlling catalysis. The spectroscopic study of the reaction of cd1NiR and its semi-apo derivative (containing the sole c heme) with NO reported here shows that c heme nitrosylation is enhanced during catalysis; this evidence has been discussed in order to assess the potential of c heme nitrosylation as a regulatory process, as observed for cytochrome c nitrosylation in mammalian mitochondria.

  19. Photoelectric converters on Cr/x/Te/y/-Zn/x/Cd/1-x/S heterojunction

    Science.gov (United States)

    Konstantinova, E. M.; Stratieva, N. R.

    The layer properties of Zn(x)Cd(1-x)S(x) are are investigated, and the use of these materials in heterojunction photocells and convertors is evaluated. Results show that the calculated lattice mismatch of the semiconductor decreases with an increase of the Zn content in the solid solutions. A Cr(x)Te(y)-Zn(x)Cd(1-x)S heterojunction is fabricated and is found to have an increase in efficiency of 1% when the open-circuit voltage is raised by about 150 mV and the other parameters are held constant. The open-circuit voltage for photocells based on Cr(x)Te(y) and Zn(x)Cd(1-x)S, with x = 0.05-0.3, is measured under 80 mW/sq cm illumination, and is shown to be lower than the open circuit voltages for Cr(x)Te(y)-Zn(x) Cd(1-x)S samples. In addition, the I-V characteristics of the samples are determined. It is concluded that the wide spectral sensitivity, the high open-circuit voltage, as well as satisfactory conversion efficiencies, of solar cells based on Cr(x)Te(y)-Zn(x)Cd(1-x)S will allow the development of solar energy convertors with improved parameters.

  20. Photoelectric converters on Cr/x/Te/y/-Zn/x/Cd/1-x/S heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Konstantinova, E.M.; Stratieva, N.R.

    1982-01-01

    The layer properties of Zn(x)Cd(1-x)S(x) are investigated, and the use of these materials in heterojunction photocells and convertors is evaluated. Results show that the calculated lattice mismatch of the semiconductor decreases with an increase of the Zn content in the solid solutions. A Cr(x)Te(y)-Zn(x)Cd(1-x)S heterojunction is fabricated and is found to have an increase in efficiency of 1% when the open-circuit voltage is raised by about 150 mV and the other parameters are held constant. The open-circuit voltage for photocells based on Cr(x)Te(y) and Zn(x)Cd(1-x)S, with x 0.05-0.3, is measured under 80 mW/sq cm illumination, and is shown to be lower than the open circuit voltages for Cr(x)Te(y)-Zn(x) Cd(1-x)S samples. In addition, the I-V characteristics of the samples are determined. It is concluded that the wide spectral sensitivity, the high open-circuit voltage, as well as satisfactory conversion efficiencies, of solar cells based on Cr(x)Te(y)-Zn(x)Cd(1-x)S will allow the development of solar energy convertors with improved parameters.

  1. Determination of cellular lipids bound to human CD1d molecules.

    Directory of Open Access Journals (Sweden)

    Daryl Cox

    Full Text Available CD1 molecules are glycoproteins that present lipid antigens at the cell surface for immunological recognition by specialized populations of T lymphocytes. Prior experimental data suggest a wide variety of lipid species can bind to CD1 molecules, but little is known about the characteristics of cellular ligands that are selected for presentation. Here we have molecularly characterized lipids bound to the human CD1d isoform. Ligands were eluted from secreted CD1d molecules and separated by normal phase HPLC, then characterized by mass spectroscopy. A total of 177 lipid species were molecularly identified, comprising glycerophospholipids and sphingolipids. The glycerophospholipids included common diacylglycerol species, reduced forms known as plasmalogens, lyso-phospholipids (monoacyl species, and cardiolipins (tetraacyl species. The sphingolipids included sphingomyelins and glycosylated forms, such as the ganglioside GM3. These results demonstrate that human CD1d molecules bind a surprising diversity of lipid structures within the secretory pathway, including compounds that have been reported to play roles in cancer, autoimmune diseases, lipid signaling, and cell death.

  2. Regulation of MHC II and CD1 antigen presentation: from ubiquity to security.

    Science.gov (United States)

    Gelin, Catherine; Sloma, Ivan; Charron, Dominique; Mooney, Nuala

    2009-02-01

    MHC class II and CD1-mediated antigen presentation on various APCs [B cells, monocytes, and dendritic cells (DC)] are subject to at least three distinct levels of regulation. The first one concerns the expression and structure of the antigen-presenting molecules; the second is based on the extracellular environment and signals of danger detected. However, a third level of regulation, which has been largely overlooked, is determined by lateral associations between antigen-presenting molecules and other proteins, their localization in specialized microdomains within the plasma membrane, and their trafficking pathways. This review focuses on features common to MHC II and CD1 molecules in their ability to activate specific T lymphocytes with the objective of addressing one basic question: What are the mechanisms regulating antigen presentation by MHC II and CD1 molecules within the same cell? Recent studies in immature DC, where MHC II and CD1 are coexpressed, suggest that the invariant chain (Ii) regulates antigen presentation by either protein. Ii could therefore favor MHC II or CD1 antigen presentation and thereby discriminate between antigens.

  3. Error Control Techniques for Efficient Multicast Streaming in UMTS Networks: Proposals andPerformance Evaluation

    Directory of Open Access Journals (Sweden)

    Michele Rossi

    2004-06-01

    Full Text Available In this paper we introduce techniques for efficient multicast video streaming in UMTS networks where a video content has to be conveyed to multiple users in the same cell. Efficient multicast data delivery in UMTS is still an open issue. In particular, suitable solutions have to be found to cope with wireless channel errors, while maintaining both an acceptable channel utilization and a controlled delivery delay over the wireless link between the serving base station and the mobile terminals. Here, we first highlight that standard solutions such as unequal error protection (UEP of the video flow are ineffective in the UMTS systems due to its inherent large feedback delay at the link layer (Radio Link Control, RLC. Subsequently, we propose a local approach to solve errors directly at the UMTS link layer while keeping a reasonably high channel efficiency and saving, as much as possible, system resources. The solution that we propose in this paper is based on the usage of the common channel to serve all the interested users in a cell. In this way, we can save resources with respect to the case where multiple dedicated channels are allocated for every user. In addition to that, we present a hybrid ARQ (HARQ proactive protocol that, at the cost of some redundancy (added to the link layer flow, is able to consistently improve the channel efficiency with respect to the plain ARQ case, by therefore making the use of a single common channel for multicast data delivery feasible. In the last part of the paper we give some hints for future research, by envisioning the usage of the aforementioned error control protocols with suitably encoded video streams.

  4. Conflict-Aware Relay Selection for Multicast in MUD based Wireless Networks

    Directory of Open Access Journals (Sweden)

    Asma Ben Hassouna

    2013-04-01

    Full Text Available Multipoint Relays (MPR [1] selection is a good step toward building a very proficient routing scheme for multicast/broadcast communications. It considers the fact that data transmitted by a node is overheard by all the users in the sender’s communication range, called the Wireless Broadcast Advantage (WBA [2][4][6]. However, when a node elects its MPR nodes it does not consider their channel qualities (i.e. they do not consider the Multi-User Diversity (MUD [3][5] factor, that has a significant influence on the network performance. Many other works consider the MUD and the rate adaptation (RA features [15][16]. However these works are distorted by severe simplifications that are made about some common wireless network problems such as: the number of transmissions, the access scheduling, the interference conflicts, etc. In this paper, we introduce three new MUD, WBA and RA based relay selection schemes. The first one proposed, called the Efficient Multi-user Diversity based Relay (E-MDR selection scheme,  is done over steps by exploiting the channel qualities in term of maximum achievable data rate (or channel capacity. The proposed EMDR based flooding strategy achieves the best multicast throughput without considering concurrent transmissions. It aims jointly (i to reduce the number of relays, (ii to maximize the throughput of each single multicast session (or partition, (iii to reduce the number of transmissions, (iv to exploit extremely the offered link capacities and as a consequence (v to enhance the allover network throughput. The second MUD, WBA and RA based relay selection scheme, called the Conflict free Multi-user Diversity based Relay (C-MDR selection scheme, performs relay selection with consideration of the interference factor. It targets (i to select relay nodes and their data transmission rates that maximize the multicast throughput, (ii to consider the effect of access scheduling when choosing relay nodes and (iii to resolve

  5. Wavelength multicasting through four-wave mixing with an optical comb source.

    Science.gov (United States)

    Ting, Hong-Fu; Wang, Ke-Yao; Stroud, Jasper R; Petrillo, Keith G; Sun, Hongcheng; Foster, Amy C; Foster, Mark A

    2017-04-17

    Based on four-wave mixing (FWM) with an optical comb source (OCS), we experimentally demonstrate 26-way or 15-way wavelength multicasting of 10-Gb/s differential phase-shift keying (DPSK) data in a highly-nonlinear fiber (HNLF) or a silicon waveguide, respectively. The OCS provides multiple spectrally equidistant pump waves leading to a multitude of FWM products after mixing with the signal. We achieve error-free operation with power penalties less than 5.7 dB for the HNLF and 4.2 dB for the silicon waveguide, respectively.

  6. Hybrid ARQ Scheme with Autonomous Retransmission for Multicasting in Wireless Sensor Networks

    Science.gov (United States)

    Jung, Young-Ho; Choi, Jihoon

    2017-01-01

    A new hybrid automatic repeat request (HARQ) scheme for multicast service for wireless sensor networks is proposed in this study. In the proposed algorithm, the HARQ operation is combined with an autonomous retransmission method that ensure a data packet is transmitted irrespective of whether or not the packet is successfully decoded at the receivers. The optimal number of autonomous retransmissions is determined to ensure maximum spectral efficiency, and a practical method that adjusts the number of autonomous retransmissions for realistic conditions is developed. Simulation results show that the proposed method achieves higher spectral efficiency than existing HARQ techniques. PMID:28245604

  7. Features of manufacturing Cd1–xZnxTe ionizing radiation detector

    Directory of Open Access Journals (Sweden)

    Tomashik Z. F.

    2013-02-01

    Full Text Available The article describes a newly-developed method of manufacturing of an operating element of the Cd1–xZnxTe-detector of ionizing radiation with high sensitivity to low-energy gamma radiation of the americium 241Am radioactive isotope. The proposed two-step method of chemical surface treatment with the use of new bromine releasing polishing etchants significantly improves the quality of the detector material and increases its specific sensitivity to ionizing radiation. This allows to use smaller Cd1–xZnxTe plates, which results in lowering of the cost of detectors.

  8. The Sensors Connectivity within SCADA Automation Environment and New Trends for Security Development during Multicasting Routing Transmission

    OpenAIRE

    Aamir Shahzad; Kalum Priyanath Udagepola; Young-keun Lee; Soojin Park; Malrey Lee

    2015-01-01

    This study examined the security of SCADA system and its protocols, more specifically, SCADA/DNP3 protocol security. To achieve the study goals, a SCADA simulation environment is designed for water pumping process through connectivity of intelligent sensors, the payload is constructed, and security is deployed inside DNP3 protocol stack and then bytes are multicast to subcontrollers.

  9. Energy-efficient multicast traffic grooming strategy based on light-tree splitting for elastic optical networks

    Science.gov (United States)

    Liu, Huanlin; Yin, Yarui; Chen, Yong

    2017-07-01

    In order to address the problem of optimizing the spectrum resources and power consumption in elastic optical networks (EONs), we investigate the potential gains by jointly employing the light-tree splitting and traffic grooming for multicast requests. An energy-efficient multicast traffic grooming strategy based on light-tree splitting (EED-MTGS-LS) is proposed in this paper. Firstly, we design a traffic pre-processing mechanism to decide the multicast requests' routing order, which considers the request's bandwidth requirement and physical hops synthetically. Then, by dividing a light-tree to some sub-light-trees and grooming the request to these sub-light-trees, the light-tree sharing ratios of multicast requests can be improved. What's more, a priority scheduling vector is constructed, which aims to improve the success rate of spectrum assignment for grooming requests. Finally, a grooming strategy is designed to optimize the total power consumption by reducing the use of transponders and IP routers during routing. Simulation results show that the proposed strategy can significantly improve the spectrum utilization and save the power consumption.

  10. Out-of-Sequence Prevention for Multicast Input-Queuing Space-Memory-Memory Clos-Network

    DEFF Research Database (Denmark)

    Yu, Hao; Ruepp, Sarah; Berger, Michael Stübert

    2011-01-01

    This paper proposes two cell dispatching algorithms for the input-queuing space-memory-memory (IQ-SMM) Closnetwork to reduce out-of-sequence (OOS) for multicast traffic. The frequent connection pattern change of DSRR results in a severe OOS problem. Based on the principle of DSRR, MFDSRR is able...

  11. Role of ANN in Secured Wireless Multicast Routing during Dynamic Channel Allocation for User Demanded Packet Optimality

    Directory of Open Access Journals (Sweden)

    Dr. B.S. Pradeep

    2011-09-01

    Full Text Available The application of Artificial Neural Network (ANNís to mobile Ad Hock Network for multicasting where the problem is to find an efficient route to transmit packets over many nodes in the network. For multicasting in MANETS which address the security and Quality of service (Q.O.S. issues on the utility database makes this area highly suitable for ANN implementation. ANN is able to learn the relationship among past, current, and future route discoveries of the different nodes in the mobility range. A wide variety of different ANN has been used for route discoveries in the few years resulting in a noticeable number of publications on the subject. This paper proposes effective and novel application of Artificial Neural Network to Secure Multicasting in MANETís with Supporting Nodes has gained a lot of attention for secure routing using an ANN model. The methodology considers selection of input Variables for the ANN, determination of the optimum number of neurons for the hidden Layer selection of Multicasting with supporting nodes routing function. The proposed ANN model uses the feed forward network using back propagation algorithms.

  12. Allosteric control of internal electron transfer in cytochrome cd1 nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Kroneck, Peter M H; Zumft, Walter G

    2003-01-01

    Cytochrome cd1 nitrite reductase is a bifunctional multiheme enzyme catalyzing the one-electron reduction of nitrite to nitric oxide and the four-electron reduction of dioxygen to water. Kinetics and thermodynamics of the internal electron transfer process in the Pseudomonas stutzeri enzyme have...

  13. Deletion of CD1d in Adipocytes Aggravates Adipose Tissue Inflammation and Insulin Resistance in Obesity.

    Science.gov (United States)

    Huh, Jin Young; Park, Jeu; Kim, Jong In; Park, Yoon Jeong; Lee, Yun Kyung; Kim, Jae Bum

    2017-04-01

    Adipose tissue inflammation is an important factor in obesity that promotes insulin resistance. Among various cell types in adipose tissue, immune cells actively regulate inflammatory responses and affect whole-body energy metabolism. In particular, invariant natural killer T (iNKT) cells contribute to mitigating dysregulation of systemic energy homeostasis by counteracting obesity-induced inflammation in adipose tissue. However, the molecular mechanisms by which adipose iNKT cells become activated and mediate anti-inflammatory roles in obese adipose tissue have not been thoroughly understood yet. In the current study, we demonstrate that adipocyte CD1d plays a key role in the stimulation of adipose iNKT cells, leading to anti-inflammatory responses in high-fat diet (HFD)-fed mice. Accordingly, adipocyte-specific CD1d-knockout (CD1d(ADKO)) mice showed reduced numbers of iNKT cells in adipose tissues and decreased responses to α-galactosylceramide-induced iNKT cell activation. Additionally, HFD-fed CD1d(ADKO) mice revealed reduced interleukin-4 expression in adipose iNKT cells and aggravated adipose tissue inflammation and insulin resistance. Collectively, these data suggest that adipocytes could selectively stimulate adipose iNKT cells to mediate anti-inflammatory responses and attenuate excess proinflammatory responses in obese adipose tissue. © 2017 by the American Diabetes Association.

  14. CD1d-restricted peripheral T cell lymphoma in mice and humans

    Science.gov (United States)

    Bachy, Emmanuel; Urb, Mirjam; Chandra, Shilpi; Robinot, Rémy; Bricard, Gabriel; de Bernard, Simon; Traverse-Glehen, Alexandra; Gazzo, Sophie; Blond, Olivier; Khurana, Archana; Baseggio, Lucile; Heavican, Tayla; Ffrench, Martine; Crispatzu, Giuliano; Mondière, Paul; Schrader, Alexandra; Taillardet, Morgan; Thaunat, Olivier; Martin, Nadine; Dalle, Stéphane; Le Garff-Tavernier, Magali; Salles, Gilles; Lachuer, Joel; Hermine, Olivier; Asnafi, Vahid; Roussel, Mikael; Lamy, Thierry; Herling, Marco; Iqbal, Javeed; Buffat, Laurent; Marche, Patrice N.; Gaulard, Philippe; Kronenberg, Mitchell; Defrance, Thierry

    2016-01-01

    Peripheral T cell lymphomas (PTCLs) are a heterogeneous entity of neoplasms with poor prognosis, lack of effective therapies, and a largely unknown pathophysiology. Identifying the mechanism of lymphomagenesis and cell-of-origin from which PTCLs arise is crucial for the development of efficient treatment strategies. In addition to the well-described thymic lymphomas, we found that p53-deficient mice also developed mature PTCLs that did not originate from conventional T cells but from CD1d-restricted NKT cells. PTCLs showed phenotypic features of activated NKT cells, such as PD-1 up-regulation and loss of NK1.1 expression. Injections of heat-killed Streptococcus pneumonia, known to express glycolipid antigens activating NKT cells, increased the incidence of these PTCLs, whereas Escherichia coli injection did not. Gene expression profile analyses indicated a significant down-regulation of genes in the TCR signaling pathway in PTCL, a common feature of chronically activated T cells. Targeting TCR signaling pathway in lymphoma cells, either with cyclosporine A or anti-CD1d blocking antibody, prolonged mice survival. Importantly, we identified human CD1d-restricted lymphoma cells within Vδ1 TCR-expressing PTCL. These results define a new subtype of PTCL and pave the way for the development of blocking anti-CD1d antibody for therapeutic purposes in humans. PMID:27069116

  15. CD1a expression in psoriatic skin following treatment with propylthiouracil, an antithyroid thioureylene

    Directory of Open Access Journals (Sweden)

    Barr Ronald J

    2003-07-01

    Full Text Available Abstract Background The antithyroid thioureylenes, propylthiouracil (PTU and methimazole (MMI, are effective in the treatment of patients with plaque psoriasis. The mechanism of action of the drugs in psoriasis is unknown. Since the drugs reduce circulating IL-12 levels in patients with Graves' hyperthyroidism, the effect of propylthiouracil on CD1a expression in psoriatic lesions was examined in biopsy samples of patients with plaque psoriasis. CD1a is a marker of differentiated skin antigen presenting cells (APC, Langerhans cells. Langerhans cells and skin monocyte/macrophages are the source of IL-12, a key cytokine involved in the events that lead to formation of the psoriatic plaque. Methods Biopsy specimens were obtained from six patients with plaque psoriasis who were treated with 300 mg propylthiouracil (PTU daily for three months. Clinical response to PTU as assessed by PASI scores, histological changes after treatment, and CD1a expression in lesional skin before and after treatment were studied. Results Despite significant improvement in clinical and histological parameters the expression of CD1a staining cells in the epidermis did not decline with propylthiouracil treatment. Conclusions It appears that the beneficial effect of propylthiouracil in psoriasis is mediated by mechanisms other than by depletion of skin antigen-presenting cells.

  16. PERIODS OF VERTEBRAL COLUMN SENSITIVITY TO BORIC ACID TREATMENT IN CD-1 MICE IN UTERO

    Science.gov (United States)

    Periods of vertebral column sensitivity to boric acid treatment in CD-1 mice in utero.Cherrington JW, Chernoff N.Department of Toxicology, North Carolina State University, Raleigh, NC 27695, USA. jana_cherrington@hotmail.comBoric acid (BA) has many uses as...

  17. Neutron Scattering Studies of the Anti-ferromagnetic Phase of Cd1-xMnxTe

    DEFF Research Database (Denmark)

    Giebultowicz, T.; Minor, W.; Buras, B.;

    1982-01-01

    Studies of the magnetic properties of crystals of the mixed semiconductors Cd1-xMnxTe indicate that: (i) for x ≤ 0.17 the crystals are paramagnetic at all temperatures, (ii) for 0.17 low...... temperatures. Neutron diffraction experiments have shown that for 0.60

  18. Optical absorption and Faraday rotation in spin doped Cd1-xHgxSe : Mn crystals

    NARCIS (Netherlands)

    Savchuk, AI; Paranchich, SY; Paranchich, LD; Romanyuk, OS; Andriychuk, MD; Nikitin, PI; Tomlinson, RD; Hill, AE; Pilkington, RD

    1998-01-01

    Optical absorption spectra and the Faraday effect in crystals of Cd1-xHgxSe : Mn have been studied. The studied samples have been characterized abrupt absorption edge and transparency region with high transmission coefficient. The measured values of Verdet constant were considerably larger than in I

  19. PERIODS OF VERTEBRAL COLUMN SENSITIVITY TO BORIC ACID TREATMENT IN CD-1 MICE IN UTERO

    Science.gov (United States)

    Periods of vertebral column sensitivity to boric acid treatment in CD-1 mice in utero.Cherrington JW, Chernoff N.Department of Toxicology, North Carolina State University, Raleigh, NC 27695, USA. jana_cherrington@hotmail.comBoric acid (BA) has many uses as...

  20. Residual endotoxin contaminations in recombinant proteins are sufficient to activate human CD1c+ dendritic cells.

    Science.gov (United States)

    Schwarz, Harald; Schmittner, Maria; Duschl, Albert; Horejs-Hoeck, Jutta

    2014-01-01

    Many commercially available recombinant proteins are produced in Escherichia coli, and most suppliers guarantee contamination levels of less than 1 endotoxin unit (EU). When we analysed commercially available proteins for their endotoxin content, we found contamination levels in the same range as generally stated in the data sheets, but also some that were higher. To analyse whether these low levels of contamination have an effect on immune cells, we stimulated the monocytic cell line THP-1, primary human monocytes, in vitro differentiated human monocyte-derived dendritic cells, and primary human CD1c+ dendritic cells (DCs) with very low concentrations of lipopolysaccharide (LPS; ranging from 0.002-2 ng/ml). We show that CD1c+ DCs especially can be activated by minimal amounts of LPS, equivalent to the levels of endotoxin contamination we detected in some commercially available proteins. Notably, the enhanced endotoxin sensitivity of CD1c+ DCs was closely correlated with high CD14 expression levels observed in CD1c+ DCs that had been maintained in cell culture medium for 24 hours. When working with cells that are particularly sensitive to LPS, even low endotoxin contamination may generate erroneous data. We therefore recommend that recombinant proteins be thoroughly screened for endotoxin contamination using the limulus amebocyte lysate test, fluorescence-based assays, or a luciferase based NF-κB reporter assay involving highly LPS-sensitive cells overexpressing TLR4, MD-2 and CD14.

  1. Multicast Delayed Authentication For Streaming Synchrophasor Data in the Smart Grid.

    Science.gov (United States)

    Câmara, Sérgio; Anand, Dhananjay; Pillitteri, Victoria; Carmo, Luiz

    2016-01-01

    Multicast authentication of synchrophasor data is challenging due to the design requirements of Smart Grid monitoring systems such as low security overhead, tolerance of lossy networks, time-criticality and high data rates. In this work, we propose inf -TESLA, Infinite Timed Efficient Stream Loss-tolerant Authentication, a multicast delayed authentication protocol for communication links used to stream synchrophasor data for wide area control of electric power networks. Our approach is based on the authentication protocol TESLA but is augmented to accommodate high frequency transmissions of unbounded length. inf TESLA protocol utilizes the Dual Offset Key Chains mechanism to reduce authentication delay and computational cost associated with key chain commitment. We provide a description of the mechanism using two different modes for disclosing keys and demonstrate its security against a man-in-the-middle attack attempt. We compare our approach against the TESLA protocol in a 2-day simulation scenario, showing a reduction of 15.82% and 47.29% in computational cost, sender and receiver respectively, and a cumulative reduction in the communication overhead.

  2. Performance Evaluation of Mesh based Multicast Reactive Routing Protocol under Black Hole Attack

    CERN Document Server

    Anita, E A Mary

    2009-01-01

    A mobile ad-hoc network is an autonomous system of mobile nodes connected by wireless links in which nodes cooperate by forwarding packets for each other thereby enabling communication beyond direct wireless transmission range. The wireless and dynamic nature of ad-hoc networks makes them vulnerable to attacks especially in routing protocols. Providing security in mobile ad-hoc networks has been a major issue over the recent years. One of the prominent mesh base reactive multicast routing protocols used in ad-hoc networks is On Demand Multicast Routing protocol (ODMRP). The security of ODMRP is compromised by a primary routing attack called black hole attack. In this attack a malicious node advertises itself as having the shortest path to the node whose packets it wants to intercept. This paper discusses the impact of black hole attack on ODMRP under various scenarios. The performance is evaluated using metrics such as packet delivery ratio and end to end delay for various numbers of senders and receivers via...

  3. Performance Analysis of Dual-Priority Multilayer Multistage Interconnection Networks under Multicast Environment

    Directory of Open Access Journals (Sweden)

    Dimitris C. Vasiliadis

    2011-06-01

    Full Text Available Next-generation network architectures strive to achieve high bandwidth and ultralow latency for the packets traversing the offered end-to-end paths. Multistage Interconnection Networks (MINs are often employed for implementing NGNs, but while MINs are fairly flexible in handling varieties of traffic loads, they tend to quickly saturate under broadcast and multicast traffic, especially at increasing size networks. As a response to this issue, multilayer MINs have been proposed, however their performance prediction and evaluation has not been studied sufficiently insofar. In this paper, we evaluate and discuss the performance of multilayer MINs under multicast traffic, considering also two levels of packet priorities, since support for multiple QoS levels is an indispensible requirement for NGNs. Different offered loads and buffer size configurations are examined in this context, and performance results are given for the two most important network performance factors, namely packet throughput and delay. We also introduce and calculate a universal performance fac­tor, which includes the importance aspect of each of the above main performance factors. The findings of this study can be used by NGN system designers in order to predict the performance of each configuration and adjust the design of their communication infrastructure to the traffic requirements at hand.

  4. Design of a Multicast Optical Packet Switch Based on Fiber Bragg Grating Technology for Future Networks

    Science.gov (United States)

    Cheng, Yuh-Jiuh; Yeh, Tzuoh-Chyau; Cheng, Shyr-Yuan

    2011-09-01

    In this paper, a non-blocking multicast optical packet switch based on fiber Bragg grating technology with optical output buffers is proposed. Only the header of optical packets is converted to electronic signals to control the fiber Bragg grating array of input ports and the packet payloads should be transparently destined to their output ports so that the proposed switch can reduce electronic interfaces as well as the bit rate. The modulation and the format of packet payloads may be non-standard where packet payloads could also include different wavelengths for increasing the volume of traffic. The advantage is obvious: the proposed switch could transport various types of traffic. An easily implemented architecture which can provide multicast services is also presented. An optical output buffer is designed to queue the packets if more than one incoming packet should reach to the same destination output port or including any waiting packets in optical output buffer that will be sent to the output port at a time slot. For preserving service-packet sequencing and fairness of routing sequence, a priority scheme and a round-robin algorithm are adopted at the optical output buffer. The fiber Bragg grating arrays for both input ports and output ports are designed for routing incoming packets using optical code division multiple access technology.

  5. Experimental Evaluation of Unicast and Multicast CoAP Group Communication.

    Science.gov (United States)

    Ishaq, Isam; Hoebeke, Jeroen; Moerman, Ingrid; Demeester, Piet

    2016-07-21

    The Internet of Things (IoT) is expanding rapidly to new domains in which embedded devices play a key role and gradually outnumber traditionally-connected devices. These devices are often constrained in their resources and are thus unable to run standard Internet protocols. The Constrained Application Protocol (CoAP) is a new alternative standard protocol that implements the same principals as the Hypertext Transfer Protocol (HTTP), but is tailored towards constrained devices. In many IoT application domains, devices need to be addressed in groups in addition to being addressable individually. Two main approaches are currently being proposed in the IoT community for CoAP-based group communication. The main difference between the two approaches lies in the underlying communication type: multicast versus unicast. In this article, we experimentally evaluate those two approaches using two wireless sensor testbeds and under different test conditions. We highlight the pros and cons of each of them and propose combining these approaches in a hybrid solution to better suit certain use case requirements. Additionally, we provide a solution for multicast-based group membership management using CoAP.

  6. Experimental Evaluation of Unicast and Multicast CoAP Group Communication

    Science.gov (United States)

    Ishaq, Isam; Hoebeke, Jeroen; Moerman, Ingrid; Demeester, Piet

    2016-01-01

    The Internet of Things (IoT) is expanding rapidly to new domains in which embedded devices play a key role and gradually outnumber traditionally-connected devices. These devices are often constrained in their resources and are thus unable to run standard Internet protocols. The Constrained Application Protocol (CoAP) is a new alternative standard protocol that implements the same principals as the Hypertext Transfer Protocol (HTTP), but is tailored towards constrained devices. In many IoT application domains, devices need to be addressed in groups in addition to being addressable individually. Two main approaches are currently being proposed in the IoT community for CoAP-based group communication. The main difference between the two approaches lies in the underlying communication type: multicast versus unicast. In this article, we experimentally evaluate those two approaches using two wireless sensor testbeds and under different test conditions. We highlight the pros and cons of each of them and propose combining these approaches in a hybrid solution to better suit certain use case requirements. Additionally, we provide a solution for multicast-based group membership management using CoAP. PMID:27455262

  7. A video conferencing system based on SDN-enabled SVC multicast

    Institute of Scientific and Technical Information of China (English)

    En-zhong YANG; Lin-kai ZHANG; Zhen YAO; Jian YANG

    2016-01-01

    Current typical video conferencing connection is bridged by a multipoint control unit (MCU), which may cause large delay and communication bottleneck for the whole system. With the development of network technology, a video conferencing system can be implemented based on software-defi ned networking (SDN), which makes the service controllable and improves the scalability and fl exibility. Additionally, a video encoding method called scalable video coding (SVC) can also help. In this paper, we propose a video conferencing architecture based on SDN-enabled SVC multicasting, which discards the traditional Internet group management protocol (IGMP) and MCU. The system implements SVC multicast streaming to satisfy different device capabilities of various conference terminals. The SDN controller is responsible for dynamically managing and controlling the layers of a video stream when a conference member faces network congestion. Also, a conference manager is designed to facilitate the management of the conference members. Experimental results show that our system can not only provide a fl exible and controllable video delivery, but also reduce the network usage while guaranteeing the quality of service (QoS) of video conferencing.

  8. Experimental Evaluation of Unicast and Multicast CoAP Group Communication

    Directory of Open Access Journals (Sweden)

    Isam Ishaq

    2016-07-01

    Full Text Available The Internet of Things (IoT is expanding rapidly to new domains in which embedded devices play a key role and gradually outnumber traditionally-connected devices. These devices are often constrained in their resources and are thus unable to run standard Internet protocols. The Constrained Application Protocol (CoAP is a new alternative standard protocol that implements the same principals as the Hypertext Transfer Protocol (HTTP, but is tailored towards constrained devices. In many IoT application domains, devices need to be addressed in groups in addition to being addressable individually. Two main approaches are currently being proposed in the IoT community for CoAP-based group communication. The main difference between the two approaches lies in the underlying communication type: multicast versus unicast. In this article, we experimentally evaluate those two approaches using two wireless sensor testbeds and under different test conditions. We highlight the pros and cons of each of them and propose combining these approaches in a hybrid solution to better suit certain use case requirements. Additionally, we provide a solution for multicast-based group membership management using CoAP.

  9. Cross-Layer Designs in Coded Wireless Fading Networks with Multicast

    CERN Document Server

    Rajawat, Ketan; Giannakis, Georgios B

    2010-01-01

    A cross-layer design along with an optimal resource allocation framework is formulated for wireless fading networks, where the nodes are allowed to perform network coding. The aim is to jointly optimize end-to-end transport layer rates, network code design variables, broadcast link flows, link capacities, average power consumption, and short-term power allocation policies. As in the routing paradigm where nodes simply forward packets, the cross-layer optimization problem with network coding is non-convex in general. It is proved however, that with network coding, dual decomposition for multicast is optimal so long as the fading at each wireless link is a continuous random variable. This lends itself to provably convergent subgradient algorithms, which not only admit a layered-architecture interpretation but also optimally integrate network coding in the protocol stack. The dual algorithm is also paired with a scheme that yields near-optimal network design variables, namely multicast end-to-end rates, network ...

  10. Research and Implementation of Multicast Technology in HFC%HFC网络组播技术研究与实现

    Institute of Scientific and Technical Information of China (English)

    王沁; 袁玲玲; 张燕; 许娜; 李翀

    2009-01-01

    A network access device (CM) based on DOCSIS 1.1 must suppress multicast traffic. The CM controls the forwarding of multicast by administratively setting parameters for the policy-filter service and by a specific multicast tracking algorithm, and the latter includes the passive IGMP mode and active IGMP mode. According to the demands of the passive IGMP mode and the characteristic that CM has a fixed host port and a fixed router port, a Data-Over-Cable IGMP Snooping protocol was designed and implemented. The protocol works on the MAC Layer, can snoop ICMP packets received by CM, maintains a list of multicast groups and can filter multicast data. The new protocol was tested in the bidirectional system platform for HDTV( High Definition Television), which consists of a self-developed PHY and MAC chip.%符合DOCSIS1.1规范的网络接入设备CM需要抑制组播.这种CM使用两种机制控制组播的转发,即设置策略过滤业务参数和专门的组播跟踪算法,而后者有passive IGMP和active IGMP两种模式.根据passive IGMP的要求和CM有固定的主机端口和固定的路由器端口的特点,设计并实现了一种电缆网络IGMP Snooping协议.该协议运行在MAC层,实现侦听CM收到的IGMP报文、维护组播组列表、过滤组播数据的功能.本设计在自主开发的物理层和MAC层芯片组成的HDTV(高清晰度电视)双向系统平台进行测试.

  11. A P2P Platform for Real-Time Multicast Video Streaming Leveraging on Scalable Multiple Descriptions to Cope with Bandwidth Fluctuations

    National Research Council Canada - National Science Library

    Lorenzo Favalli; Marco Folli; Alfio Lombardo; Diego Reforgiato; Giovanni Schembra

    2011-01-01

    ... and performance.The target of this paper is to propose a content delivery system for real-time streaming services based ona peer-to-peer approach that exploits multicast overlay organization of the peers to address...

  12. Raman spectroscopy of Cd1-xMnxS quantum dots

    Science.gov (United States)

    Romcevic, N.; Kostic, R.; Romcevic, M.; Comor, M. I.; Nedeljkovic, J. M.

    2005-12-01

    Powders consisting of 44 Å Cd1-xMnxS (x = 0; 0.05; 0.1; 0.15; 0.3) quantum dots (QDs) were synthesized using the colloidal chemistry method and characterized by Raman scattering measurements. The dominant Raman line of the 44 Å Cd1-xMnxS QDs was at about 300 cm-1 showing asymmetric broadening for ω < 300 cm-1. A significant change in the intensity of the first harmonic for different x and excitation energies was noticed. Also, the second harmonic of confined Raman modes was experimentally observed. A theoretical model was used to calculate the relative contributions of the confined Raman scattering modes for the 44 Å CdS QDs and satisfactory agreement with experimental results was found.

  13. Purification, growth, and characterization of Zn(x)Cd(1-x)Se crystals

    Science.gov (United States)

    Silberman, E.; Burger, A.; Chen, W.; Henderson, D. O.; Morgan, S. H.; Springer, John M.; Yao, Y.

    1989-01-01

    The purification of starting materials which were used in the growth of Zn(x)Cd(1-x)Se (x = 0.2) single crystals using the traveling solution method (TSM) is reported. Up to 13 cm long single crystals and as grown resistivities of 6 x 10(exp 12) ohm/cm could be achieved. Infrared and Raman spectra of Zn(0.2)Cd(0.8)Se are also presented and discussed.

  14. Thermographic analyses of the growth of Cd1-xZnxTe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kopach, O.V.; Bolotnikov, A.; Shcherbak, Larysa P.; Fochuk, Petro M.; and James, Ralph B.

    2010-08-01

    Bulk Cd1-xZnxTe (0

  15. Role of CD1A and HSP60 in the antitumoral response of oesophageal cancer

    OpenAIRE

    Giovanni Zummo; Francesco Cappello; Felicia Farina; Lorenzo Marasà; Rita Anzalone; Giampiero La Rocca; Simona Corrao

    2011-01-01

    Oesophageal cancer (OC) is one of the most common and severe forms of tumor. A wider knowledge of molecular mechanisms which lead to a normal epithelium becoming a neoplasm may reveal new strategies to improve treatment and outcome of this disease. In this review, we report recent findings concerning molecular events which take place during carcinogenesis of the oesophagus. In particular, we focus on the role of two molecules, CD1a and Hsp60, which are overexpressed in oesophageal and many ot...

  16. Neutron Diffraction Study of Magnetic Ordering in Cd1-xMnxTe

    DEFF Research Database (Denmark)

    Giebultowicz, T.; Kepa, H.; Buras, B.;

    1981-01-01

    Neutron diffraction experiments were performed on Cd1−xMnxTe crystals for x=0.40, 0.60, 0.63, 0.65 and 0.70. Magnetic Bragg scattering was observed at low temperatures for xgreater-or-equal, slanted0.60 corresponding to the Type III antiferromagnetic ordering of a f.c.c. sub-lattice. The Néel tem...... temperatures decreasing with x were determined and the critical concentration xc was estimated....

  17. Single and Multicasting Inverted-Wavelength Conversion at 80 Gb/s Based on a Single Semiconductor Optical Amplifier

    Institute of Scientific and Technical Information of China (English)

    HUANG Xi; QIN Cui; YU Yu; ZHANG Xin-Liang

    2011-01-01

    We experimentally demonstrate single and multicasting inverted wavelength conversion at 80Gb/s by using the cross-gain modulation and cross-phase modulation in a single semiconductor optical amplifier (SOA).In all the cases,converted signals with a high extinction ratio (ER) and large eye opening are obtained.For singlechannel wavelength conversion,the ER of the output signal is as high as 30.10dB.For three-channel wavelength multicasting,high quality converted signals could also be observed.The ERs with three channels are 21.54 dB,18.58dB and 17.72dB,respectively.Thus,one- and three-channel wavelength conversion with high performance can be achieved by using a single quantum-well SOA.All-optical wavelength conversion (AOWC).[1-4] is a key technology in wavelength division multiplexed (WDM) networks.AOWC based on semiconductor optical amplifiers (SOAs) is widely used due to its potential integration and power efficieney.Many SOAbased AOWCs have been theoretically and experimentally demonstrated.[5,6] Furthermore,wavelength multicasting is very important in all optical signal processing systems.Wavelength multicasting is a signal processing function that can be used to transfer the information carried by a channel at a certain input wavelength on different output wavelengths.Recently,many methods have been proposed for single wavelength conversion and wavelength multieasting.High nonlinear fibers,electro-absorption modulators and SOAs[7] have been used as nonlinear media.How ever,most of the schemes suffer from drawbacks such as complex architecture,a fairly high optical input power requirement,polarization dependence and so on.%We experimentally demonstrate single and multicasting inverted wavelength conversion at 80Gb/s by using the cross-gain modulation and cros-phase modulation in a single semiconductor optical amplifier (SOA). In all the cases, converted signals with a high extinction ratio (ER) and largo eye opening are obtained. For single-channel wavelength

  18. DEVELOPMENTAL TOXICITY OF METHANOL: PATHOGENESIS IN CD-1 AND C57BL/6J MICE EXPOSED IN WHOLE EMBRYO CULTURE

    Science.gov (United States)

    BACKGROUND: Methanol causes axial skeleton and craniofacial defects in both CD-1 and C57BL/6J mice during gastrulation, but C57BL/6J embryos are more severely affected. We evaluated methanol-induced pathogenesis in CD-1 and C57BL/6J embryos exposed during gastrulation in whole em...

  19. Studies of Spectroscopic Ellipsometry in Cd1-xMnx Te/CdTe Superlattices

    Institute of Scientific and Technical Information of China (English)

    CHEN Chen-Jia; WANG Xue-Zhong; Vittorio BELLANI; Angiolino STELLA

    2006-01-01

    Cd1-xMnxTe/CdTe superlattices and thin films were grown by molecular beam epitaxy on GaAs (001) substrates. Spectroscopic ellipsometry measurements were performed on Cd1-xMnxTe/CdTe superlattices with compositions x = 0.4, 0.8, and Cd1-xMnxTe thin films with x = 0.2, 0.4, 0.6 at room temperature in the photon energy range 1.4-5eV. In superlattices the pseudodielectric functions measured by ellipsometry show specific features related to the exciton transition between quantized interbands. The exciton transitions related to the heavy holes of 11H, 22H, and 33H are observed and identified. In thin films spectroscopic ellipsometry allows the clear identification of the energy gap E0. Additionally, critical point transitions are observable in both the spectra of the superlattices and films. Photoreflectance spectra were also performed at room temperature in order to compare with our ellipsometry results. After taking into account the strain-induced and quantum confinement effects, the theoretical calculations are in good agreement with our experimental spectra. Ellipsometry appears to be a suited technique to monitor the MBE growth, ultimately also in situ, of diluted magnetic low-dimensional systems.

  20. Interview: glycolipid antigen presentation by CD1d and the therapeutic potential of NKT cell activation.

    Science.gov (United States)

    Kronenberg, Mitchell

    2007-01-01

    Natural Killer T cells (NKT) are critical determinants of the immune response to cancer, regulation of autioimmune disease, clearance of infectious agents, and the development of artheriosclerotic plaques. In this interview, Mitch Kronenberg discusses his laboratory's efforts to understand the mechanism through which NKT cells are activated by glycolipid antigens. Central to these studies is CD1d--the antigen presenting molecule that presents glycolipids to NKT cells. The advent of CD1d tetramer technology, a technique developed by the Kronenberg lab, is critical for the sorting and identification of subsets of specific glycolipid-reactive T cells. Mitch explains how glycolipid agonists are being used as therapeutic agents to activate NKT cells in cancer patients and how CD1d tetramers can be used to assess the state of the NKT cell population in vivo following glycolipid agonist therapy. Current status of ongoing clinical trials using these agonists are discussed as well as Mitch's prediction for areas in the field of immunology that will have emerging importance in the near future.

  1. Hollow ZnxCd1-xS nanospheres with enhanced photocatalytic activity under visible light.

    Science.gov (United States)

    Jin, Ying; Zhang, Haoyun; Song, Chuang; Wang, Lanfang; Lu, Qingyi; Gao, Feng

    2016-07-22

    Formation of solid solutions is a good strategy to acquire materials with special properties and bring forth new type of applications or enhance the performance of currently existing devices. In this study, hollow ZnxCd1-xS nanospheres with different molar ratios were synthesized via a facile hydrothermal process. The products were fully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and UV-vis absorption spectroscopy. It was found that the photocatalysis performance of the as-prepared samples could be enhanced by formation of ZnxCd1-xS solid solutions. In addition, their photocatalytic activities are dependent on the Zn/Cd molar ratios and nanostructures of ZnxCd1-xS solid solutions. Hollow Zn0.2Cd0.8S spheres exhibit extremely high photocatalytic activity and good re-usability, and the photocatalytic conversion of RhB reaches as high as 96% after 50 min of irradiation.

  2. MEMS reliability

    CERN Document Server

    Hartzell, Allyson L; Shea, Herbert R

    2010-01-01

    This book focuses on the reliability and manufacturability of MEMS at a fundamental level. It demonstrates how to design MEMs for reliability and provides detailed information on the different types of failure modes and how to avoid them.

  3. Underwater Acoustic Networks: Channel Models and Network Coding based Lower Bound to Transmission Power for Multicast

    CERN Document Server

    Lucani, Daniel E; Stojanovic, Milica

    2008-01-01

    The goal of this paper is two-fold. First, to establish a tractable model for the underwater acoustic channel useful for network optimization in terms of convexity. Second, to propose a network coding based lower bound for transmission power in underwater acoustic networks, and compare this bound to the performance of several network layer schemes. The underwater acoustic channel is characterized by a path loss that depends strongly on transmission distance and signal frequency. The exact relationship among power, transmission band, distance and capacity for the Gaussian noise scenario is a complicated one. We provide a closed-form approximate model for 1) transmission power and 2) optimal frequency band to use, as functions of distance and capacity. The model is obtained through numerical evaluation of analytical results that take into account physical models of acoustic propagation loss and ambient noise. Network coding is applied to determine a lower bound to transmission power for a multicast scenario, fo...

  4. Network-Level Cooperative Protocols for Wireless Multicasting: Stable Throughput Analysis and Use of Network Coding

    CERN Document Server

    Fanous, Anthony

    2010-01-01

    In this paper, we investigate the impact of network coding at the relay node on the stable throughput rate in multicasting cooperative wireless networks. The proposed protocol adopts Network-level cooperation in contrast to the traditional physical layer cooperative protocols and in addition uses random linear network coding at the relay node. The traffic is assumed to be bursty and the relay node forwards its packets during the periods of source silence which allows better utilization for channel resources. Our results show that cooperation will lead to higher stable throughput rates than conventional retransmission policies and that the use of random linear network coding at the relay can further increase the stable throughput with increasing Network Coding field size or number of packets over which encoding is performed.

  5. Advanced Broadcast/Multicast Channel Capable Carrier Reuse WDM-PON

    Directory of Open Access Journals (Sweden)

    Ashish Nema

    2013-02-01

    Full Text Available Advanced broadcast/multicast carriers reuse WDM-PON is mainly used to provide the broadcast and unicast signal at the destination end. It uses the splitting capability of a power splitter and the cyclic property of arrayed waveguide grating at the middle remote node. The broadcast channel with the help of AWG and with a dedicated unicast channel can be overlaid and subsequently transmitted to each Optical network unit (ONU simultaneously. Another advantage of this WDM-PON a very small interface between the broadcast channel and with the unicast channel and it is shared by all ONU. The optical carrier to subcarrier ratio on the bit error rate performance can be minimized by increasing the extinction ratio of the delay interferometer used at remote node. The result is implemented by opti-system 7.0 software tools

  6. Application of Modified Ant Colony Optimization (MACO for Multicast Routing Problem

    Directory of Open Access Journals (Sweden)

    Sudip Kumar Sahana

    2016-04-01

    Full Text Available It is well known that multicast routing is combinatorial problem finds the optimal path between source destination pairs. Traditional approaches solve this problem by establishment of the spanning tree for the network which is mapped as an undirected weighted graph. This paper proposes a Modified Ant Colony Optimization (MACO algorithm which is based on Ant Colony System (ACS with some modification in the configuration of starting movement and in local updation technique to overcome the basic limitations of ACS such as poor initialization and slow convergence rate. It is shown that the proposed Modified Ant Colony Optimization (MACO shows better convergence speed and consumes less time than the conventional ACS to achieve the desired solution.

  7. The Convergence Scheme on Network Utility Maximization in Wireless Multicast Networks

    Directory of Open Access Journals (Sweden)

    Y. Chen

    2013-08-01

    Full Text Available With the ever-increasing wireless data application recently, considerable efforts have been focused on the designof distributed explicit rate scheme based on Network Utility Maximization (NUM or wireless multi-hop meshnetworks. This paper describes a novel wireless multi-hop multicast flow control scheme for wireless meshnetworks via 802.11, which is based on the distributed self-turning Optimal Proportional plus Second-orderDifferential (OPSD controller. The control scheme, which is located at the sources in the wireless multicastnetworks, can ensure short convergence time by regulating the transmission rate. We further analyze thetheoretical aspects of the proposed algorithm. Simulation results demonstrate the efficiency of the proposedscheme in terms of fast response time, low packet loss and error ration.

  8. A MULTICAST KEY MANAGEMENT SCHEME BASED ON CHARACTERISTIC VALUES OF MEMBERS

    Institute of Scientific and Technical Information of China (English)

    Du Xiaoqiang; Bao Wansu; Fu Xiangqun

    2012-01-01

    A new collusion attack on Pour-like schemes is proposed in this paper.Then,we present a collusion-free centralized multicast key management scheme based on characteristic values of members.The re-keying method that other group members calculate new keys when a member is joining or leaving is also designed.It achieves forward secrecy and backward secrecy.Compared with typical existing centralized schemes,the storage of Group Key Controller (GKC) in our scheme halves the storage overhead of others,and communication overhead of GKC is 2 in case of joining re-keying.Especially,the leaving re-keying overhead is log2 n,and the overall performance is excellent.

  9. Throughput, Energy and Overhead of Multicast Device-to-Device Communications with Network Coded Cooperation

    DEFF Research Database (Denmark)

    Hernandez Marcano, Nestor Javier; Heide, Janus; Lucani Rötter, Daniel Enrique

    2016-01-01

    Cooperation strategies in mobile networks typically rely in short range technologies, like LTE-A Device to Device (D2D) communications, for data exchange between devices forming mobile clouds. These communications provide a better device experience since the clouds offload the network. Nevertheless......, this assumes that the throughput gains and energy savings in multicasting are much larger between devices than the base station to the receivers. However, current mobile networks suffer from many different issues varying the performance in data rates, which calls into question these assumptions. Therefore...... an analytical framework with numerical results showing: (i) gains of several fold can be attained even if the in-device data rates is moderately larger (2x) than the cellular link data rate and (ii) that is feasible to attain less than 3% total mean overhead with the proposed codes. This is fairly lower than...

  10. Context-based user grouping for multi-casting in heterogeneous radio networks

    Science.gov (United States)

    Mannweiler, C.; Klein, A.; Schneider, J.; Schotten, H. D.

    2011-08-01

    Along with the rise of sophisticated smartphones and smart spaces, the availability of both static and dynamic context information has steadily been increasing in recent years. Due to the popularity of social networks, these data are complemented by profile information about individual users. Making use of this information by classifying users in wireless networks enables targeted content and advertisement delivery as well as optimizing network resources, in particular bandwidth utilization, by facilitating group-based multi-casting. In this paper, we present the design and implementation of a web service for advanced user classification based on user, network, and environmental context information. The service employs simple and advanced clustering algorithms for forming classes of users. Available service functionalities include group formation, context-aware adaptation, and deletion as well as the exposure of group characteristics. Moreover, the results of a performance evaluation, where the service has been integrated in a simulator modeling user behavior in heterogeneous wireless systems, are presented.

  11. Throughput, Energy and Overhead of Multicast Device-to-Device Communications with Network Coded Cooperation

    DEFF Research Database (Denmark)

    Hernandez, Nestor; Heide, Janus; Roetter, Daniel Enrique Lucani

    2017-01-01

    Cooperation strategies in mobile networks typically rely in short range technologies, like LTE-A Device to Device (D2D) communications, for data exchange between devices forming mobile clouds. These communications provide a better device experience since the clouds offload the network. Nevertheless...... an analytical framework with numerical results showing: (i) gains of several fold can be attained even if the in-device data rates is moderately larger (2x) than the cellular link data rate and (ii) that is feasible to attain less than 3% total mean overhead with the proposed codes. This is fairly lower than......, a first objective of this work is to assess the operating regions where employing cooperation results in higher throughput and/or energy savings. We consider multicast scenarios with network coded mechanisms employing Random Linear Network Coding (RLNC). However, although RLNC is good for low amount...

  12. Hypo-Steiner heuristic for multicast routing in all-optical WDM mesh networks

    CERN Document Server

    Zhou, Fen; Cousin, Bernard; 10.1007/s11107-010-0243-5

    2010-01-01

    In sparse light splitting all-optical WDM networks, the more destinations a light-tree can accommodate, the fewer light-trees andwavelengths amulticast session will require. In this article, a Hypo-Steiner light-tree algorithm (HSLT) is proposed to construct a HSLT light-tree to include as many destinations as possible. The upper bound cost of the light-trees built by HSLT is given as N(N -1)/2, where N is the number of nodes in the network. The analytical model proves that, under the same condition, more destinations could be held in a HSLT than a Member-Only (Zhang et al., J. Lightware Technol, 18(12), 1917-1927 2000.) light-tree. Extensive simulations not only validate the proof but also show that the proposed heuristic outperforms the existing multicast routing algorithms by a large margin in terms of link stress, throughput, and efficiency ofwavelength usage.

  13. A Secure and Stable Multicast Overlay Network with Load Balancing for Scalable IPTV Services

    Directory of Open Access Journals (Sweden)

    Tsao-Ta Wei

    2012-01-01

    Full Text Available The emerging multimedia Internet application IPTV over P2P network preserves significant advantages in scalability. IPTV media content delivered in P2P networks over public Internet still preserves the issues of privacy and intellectual property rights. In this paper, we use SIP protocol to construct a secure application-layer multicast overlay network for IPTV, called SIPTVMON. SIPTVMON can secure all the IPTV media delivery paths against eavesdroppers via elliptic-curve Diffie-Hellman (ECDH key exchange on SIP signaling and AES encryption. Its load-balancing overlay tree is also optimized from peer heterogeneity and churn of peer joining and leaving to minimize both service degradation and latency. The performance results from large-scale simulations and experiments on different optimization criteria demonstrate SIPTVMON's cost effectiveness in quality of privacy protection, stability from user churn, and good perceptual quality of objective PSNR values for scalable IPTV services over Internet.

  14. Multicast Services of QoS-Aware Active Queue Management over IP Multimedia Applications

    Science.gov (United States)

    Hwang, I.-Shyan; Hwang, Bor-Jiunn; Chang, Pen-Ming

    2010-10-01

    Recently, the multimedia services such as IPTV, video conference emerges to be the main traffic source. When UDP coexists with TCP, it induces not only congestion collapse but also unfairness problem. In this paper, a new Active Queue Management (AQM) algorithm, called Traffic Sensitive Active Queue Management (TSAQM), is proposed for providing multimedia services. The TSAQM comprise Dynamic Weight Allocate Scheme (DWAS) and Service Guarantee Scheme (SGS), the purpose of DWAS is to allocate resource with fairness and high end-user utility, and the purpose of SGS is to determine the satisfactory threshold (TH) and threshold region (TR). Several objectives of this proposed scheme include achieving high end-user utility for video service, considering the multicast as well as unicast proprieties to meet inter-class fairness and achieving the QoS requirement by adjusting the thresholds adaptively based on traffic situations.

  15. ON THE OPTIMAL MULTI-RATE THROUGHPUT FOR MULTICAST WITH NETWORK CODING

    Institute of Scientific and Technical Information of China (English)

    Zhang Mu; Zhang Shunyi

    2006-01-01

    This paper investigates the maximal achievable multi-rate throughput problem of a multicast session at the presence of network coding. Deviating from previous works which focus on single-rate network coding, our work takes the heterogeneity of sinks into account and provides multiple data layers to address the problem. Firstly formulated is the maximal achievable throughput problem with the assumption that the data layers are independent and layer rates are static. It is proved that the problem in this case is, unfortunately,Non-deterministic Polynomial-time (NP)-hard. In addition, our formulation is extended to the problems with dependent layers and dynamic layers. Furthermore, the approximation algorithm which satisfies certain fairness is proposed.

  16. Noise performance of phase-insensitive frequency multicasting in parametric mixer with finite dispersion.

    Science.gov (United States)

    Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Huynh, Chris K; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2013-07-29

    Noise performance of dual-pump, multi-sideband parametric mixer operated in phase-insensitive mode is investigated theoretically and experimentally. It is shown that, in case when a large number of multicasting idlers are generated, the noise performance is strictly dictated by the dispersion characteristics of the mixer. We find that the sideband noise performance is significantly degraded in anomalous dispersion region permitting nonlinear noise amplification. In contrast, in normal dispersion region, the noise performance converges to the level of four-sideband parametric process, rather than deteriorates with increased sideband creation. Low noise generation mandates precise dispersion-induced phase mismatch among pump and sideband waves in order to control the noise coupling. We measure the noise performance improvement for a many-sideband, multi-stage mixer by incorporating new design technique.

  17. Energy Effective Congestion Control for Multicast with Network Coding in Wireless Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Chuanxin Zhao

    2014-01-01

    Full Text Available In order to improve network throughput and reduce energy consumption, we propose in this paper a cross-layer optimization design that is able to achieve multicast utility maximization and energy consumption minimization. The joint optimization of congestion control and power allocation is formulated to be a nonlinear nonconvex problem. Using dual decomposition, a distributed optimization algorithm is proposed to avoid the congestion by control flow rate at the source node and eliminate the bottleneck by allocating the power at the intermediate node. Simulation results show that the cross-layer algorithm can increase network performance, reduce the energy consumption of wireless nodes and prolong the network lifetime, while keeping network throughput basically unchanged.

  18. Dynamic Programming Optimization of Multi-rate Multicast Video-Streaming Services

    Directory of Open Access Journals (Sweden)

    Nestor Michael Caños Tiglao

    2010-06-01

    Full Text Available In large scale IP Television (IPTV and Mobile TV distributions, the video signal is typically encoded and transmitted using several quality streams, over IP Multicast channels, to several groups of receivers, which are classified in terms of their reception rate. As the number of video streams is usually constrained by both the number of TV channels and the maximum capacity of the content distribution network, it is necessary to find the selection of video stream transmission rates that maximizes the overall user satisfaction. In order to efficiently solve this problem, this paper proposes the Dynamic Programming Multi-rate Optimization (DPMO algorithm. The latter was comparatively evaluated considering several user distributions, featuring different access rate patterns. The experimental results reveal that DPMO is significantly more efficient than exhaustive search, while presenting slightly higher execution times than the non-optimal Multi-rate Step Search (MSS algorithm.

  19. ON MULTICAST TREE CONSTRUCTION IN IPV4-IPV6 HYBRID NETWORK

    Institute of Scientific and Technical Information of China (English)

    Zhang Chao; Zhang Yuan; Huang Yongfeng; Li Xing

    2010-01-01

    With the IPv4 addresses exhausting and IPv6 emerging,the Peer-to-Peer (P2P) overlay is becoming increasingly heterogeneous and complex: pure IPv4,dual stack and pure IPv6 hosts coexist,and the connectivity limitation between IPv4 and IPv6 hosts requires the overlay protocols to be fit for this hybrid situation. This paper sets out to answer the question of how to construct multicast tree on top of IPv4-IPv6 hybrid network. Our solution is a New Greedy Algorithm (NGA) which eliminates the problem of joining failure in the hybrid network and keeps the efficiency of greedy algorithm in tree construction. Simulation results show that our algorithm has excellent performance,which is very close to the optimal in many cases.

  20. Combined Wavelet Video Coding and Error Control for Internet Streaming and Multicast

    Directory of Open Access Journals (Sweden)

    Tianli Chu

    2003-01-01

    Full Text Available This paper proposes an integrated approach to Internet video streaming and multicast (e.g., receiver-driven layered multicast (RLM by McCanne based on combined wavelet video coding and error control. We design a packetized wavelet video (PWV coder to facilitate its integration with error control. The PWV coder produces packetized layered bitstreams that are independent among layers while being embedded within each layer. Thus, a lost packet only renders the following packets in the same layer useless. Based on the PWV coder, we search for a multilayered error-control strategy that optimally trades off source and channel coding for each layer under a given transmission rate to mitigate the effects of packet loss. While both the PWV coder and the error-control strategy are new—the former incorporates embedded wavelet video coding and packetization and the latter extends the single-layered approach for RLM by Chou et al.—the main distinction of this paper lies in the seamless integration of the two parts. Theoretical analysis shows a gain of up to 1 dB on a channel with 20% packet loss using our combined approach over separate designs of the source coder and the error-control mechanism. This is also substantiated by our simulations with a gain of up to 0.6 dB. In addition, our simulations show a gain of up to 2.2 dB over previous results reported by Chou et al.

  1. Software reliability

    CERN Document Server

    Bendell, A

    1986-01-01

    Software Reliability reviews some fundamental issues of software reliability as well as the techniques, models, and metrics used to predict the reliability of software. Topics covered include fault avoidance, fault removal, and fault tolerance, along with statistical methods for the objective assessment of predictive accuracy. Development cost models and life-cycle cost models are also discussed. This book is divided into eight sections and begins with a chapter on adaptive modeling used to predict software reliability, followed by a discussion on failure rate in software reliability growth mo

  2. Supporting QoS in MANET by a Fuzzy Priority Scheduler and Performance Analysis with Multicast Routing Protocols

    Directory of Open Access Journals (Sweden)

    Shanmugavel S

    2005-01-01

    Full Text Available Mobile ad hoc network is an autonomous system of mobile nodes characterized by wireless links. The major challenge in ad hoc networks lies in adapting multicast communication to environments, where mobility is unlimited and failures are frequent. Such problems increase the delays and decrease the throughput. To meet these challenges, to provide QoS, and hence to improve the performance, a scheduler can be used. In this paper we design a fuzzy-based priority scheduler to determine the priority of the packets. The performance of the scheduler is studied with the multicast routing protocols. The scheduler is evaluated in terms of the quantitative metrics such as packet delivery ratio and average end-to-end delay and the results are found to be encouraging.

  3. Supporting QoS in MANET by a Fuzzy Priority Scheduler and Performance Analysis with Multicast Routing Protocols

    Directory of Open Access Journals (Sweden)

    Gomathy C.

    2005-01-01

    Full Text Available Mobile ad hoc network is an autonomous system of mobile nodes characterized by wireless links. The major challenge in ad hoc networks lies in adapting multicast communication to environments, where mobility is unlimited and failures are frequent. Such problems increase the delays and decrease the throughput. To meet these challenges, to provide QoS, and hence to improve the performance, a scheduler can be used. In this paper we design a fuzzy-based priority scheduler to determine the priority of the packets. The performance of the scheduler is studied with the multicast routing protocols. The scheduler is evaluated in terms of the quantitative metrics such as packet delivery ratio and average end-to-end delay and the results are found to be encouraging.

  4. Efficiency Intra-Cluster Device-to-Device Relay Selection for Multicast Services Based on Combinatorial Auction

    Directory of Open Access Journals (Sweden)

    Yong Zhang

    2015-12-01

    Full Text Available In Long Term Evolution-Advanced (LTE-A networks, Device-to-device (D2D communications can be utilized to enhance the performance of multicast services by leveraging D2D relays to serve nodes with worse channel conditions within a cluster. For traditional D2D relay schemes, D2D links with poor channel condition may be the bottleneck of system sum data rate. In this paper, to optimize the throughput of D2D communications, we introduce an iterative combinatorial auction algorithm for efficient D2D relay selection. In combinatorial auctions, the User Equipments (UEs that fails to correctly receive multicast data from eNodeB (eNB are viewed as bidders that compete for D2D relays, while the eNB is treated as the auctioneer. We also give properties of convergency and low-complexity and present numerical simulations to verify the efficiency of the proposed algorithm.

  5. Plasticity of migrating CD1b+ and CD1b- lymph dendritic cells in the promotion of Th1, Th2 and Th17 in response to Salmonella and helminth secretions.

    Directory of Open Access Journals (Sweden)

    Michel Olivier

    Full Text Available Dendritic cells (DCs are pivotal in the development of specific T-cell responses to control pathogens, as they govern both the initiation and the polarization of adaptive immunity. To investigate the capacities of migrating DCs to respond to pathogens, we used physiologically generated lymph DCs (L-DCs. The flexible polarization of L-DCs was analysed in response to Salmonella or helminth secretions known to induce different T cell responses. Mature conventional CD1b(+ L-DCs showed a predisposition to promote pro-inflammatory (IL-6, pro-Th1 (IL-12p40 and anti-inflammatory (IL-10 responses which were amplified by Salmonella, and limited to only IL-6 induction by helminth secretions. The other major population of L-DCs did not express the CD1b molecule and displayed phenotypic features of immaturity compared to CD1b(+ L-DCs. Salmonella infection reduced the constitutive expression of TNF-α and IL-4 mRNA in CD1b(- L-DCs, whereas this expression was not affected by helminth secretions. The cytokine response of T cells promoted by L-DCs was analysed in T cell subsets after co-culture with Salmonella or helminth secretion-driven CD1b(+ or CD1b(- L-DCs. T cells preferentially expressed the IL-17 gene, and to a lesser extent the IFN-γ and IL-10 genes, in response to Salmonella-driven CD1b(+ L-DCs, whereas a preferential IL-10, IFN-γ and IL-17 gene expression was observed in response to Salmonella-driven CD1b(- L-DCs. In contrast, a predominant IL-4 and IL-13 gene expression by CD4(+ and CD8(+ T cells was observed after stimulation of CD1b(+ and CD1b(- L-DCs with helminth secretions. These results show that mature conventional CD1b(+ L-DCs maintain a flexible capacity to respond differently to pathogens, that the predisposition of CD1b(- L-DCs to promote a Th2 response can be oriented towards other Th responses, and finally that the modulation of migrating L-DCs responses is controlled more by the pathogen encountered than the L-DC subsets.

  6. Effect of Cage-Induced Stereotypies on Measures of Affective State and Recurrent Perseveration in CD-1 and C57BL/6 Mice

    Science.gov (United States)

    Novak, Janja; Bailoo, Jeremy D.; Melotti, Luca; Würbel, Hanno

    2016-01-01

    Stereotypies are abnormal repetitive behaviour patterns that are highly prevalent in laboratory mice and are thought to reflect impaired welfare. Thus, they are associated with impaired behavioural inhibition and may also reflect negative affective states. However, in mice the relationship between stereotypies and behavioural inhibition is inconclusive, and reliable measures of affective valence are lacking. Here we used an exploration based task to assess cognitive bias as a measure of affective valence and a two-choice guessing task to assess recurrent perseveration as a measure of impaired behavioural inhibition to test mice with different forms and expression levels of stereotypic behaviour. We trained 44 CD-1 and 40 C57BL/6 female mice to discriminate between positively and negatively cued arms in a radial maze and tested their responses to previously inaccessible ambiguous arms. In CD-1 mice (i) mice with higher stereotypy levels displayed a negative cognitive bias and this was influenced by the form of stereotypy performed, (ii) negative cognitive bias was evident in back-flipping mice, and (iii) no such effect was found in mice displaying bar-mouthing or cage-top twirling. In C57BL/6 mice neither route-tracing nor bar-mouthing was associated with cognitive bias, indicating that in this strain these stereotypies may not reflect negative affective states. Conversely, while we found no relation of stereotypy to recurrent perseveration in CD-1 mice, C57BL/6 mice with higher levels of route-tracing, but not bar-mouthing, made more repetitive responses in the guessing task. Our findings confirm previous research indicating that the implications of stereotypies for animal welfare may strongly depend on the species and strain of animal as well as on the form and expression level of the stereotypy. Furthermore, they indicate that variation in stereotypic behaviour may represent an important source of variation in many animal experiments. PMID:27145080

  7. Retinoic acid regulates CD1d gene expression at the transcriptional level in human and rodent monocytic cells.

    Science.gov (United States)

    Chen, Qiuyan; Ross, A Catharine

    2007-04-01

    CD1d belongs to a group of nonclassical antigen-presenting molecules that present glycolipid antigens and thereby activate natural killer T (NKT) cells, a subset of bifunctional T cells. Little is known so far regarding the expression and physiologic regulation of CD1d. Here we show that all-trans-retinoic acid (RA), the active metabolite of vitamin A, rapidly (1 hr after treatment) increases CD1d mRNA in human and rodent monocytic cells at a physiologic dose (10 nM). The induction is RA specific and RA receptor (RAR) dependent-RA and an RARalpha agonist, Am580, both had a pronounced positive effect, whereas the addition of RARalpha antagonist partially blocked the increase in CD1d mRNA induced by RA and Am580. The induction was also completely blocked by the presence of actinomycin D. A putative RA-response element was identified in the distal 5' flanking region of the CD1d gene, which binds nuclear retinoid receptors and was responsive to RA in both gel mobility shift assay and transient transfection assay in THP-1 cells. These results further confirmed the transcriptional regulation of RA in CD1d gene expression. Moreover, RA significantly increased alpha-galactosylceramide-induced spleen cell proliferation. These studies together provide evidence for a previously unknown mechanism of CD1d gene expression regulation by RA and suggest that RA is a significant modulator of NKT cell activation.

  8. Genetic variation and population substructure in outbred CD-1 mice: implications for genome-wide association studies.

    Directory of Open Access Journals (Sweden)

    Kimberly A Aldinger

    Full Text Available Outbred laboratory mouse populations are widely used in biomedical research. Since little is known about the degree of genetic variation present in these populations, they are not widely used for genetic studies. Commercially available outbred CD-1 mice are drawn from an extremely large breeding population that has accumulated many recombination events, which is desirable for genome-wide association studies. We therefore examined the degree of genome-wide variation within CD-1 mice to investigate their suitability for genetic studies. The CD-1 mouse genome displays patterns of linkage disequilibrium and heterogeneity similar to wild-caught mice. Population substructure and phenotypic differences were observed among CD-1 mice obtained from different breeding facilities. Differences in genetic variation among CD-1 mice from distinct facilities were similar to genetic differences detected between closely related human populations, consistent with a founder effect. This first large-scale genetic analysis of the outbred CD-1 mouse strain provides important considerations for the design and analysis of genetic studies in CD-1 mice.

  9. CD99 isoforms regulate CD1a expression in human monocyte-derived DCs through ATF-2/CREB-1 phosphorylation.

    Science.gov (United States)

    Mahiddine, Karim; Mallavialle, Aude; Bziouech, Hanen; Larbret, Frédéric; Bernard, Alain; Bernard, Ghislaine

    2016-06-01

    CD1a expression is considered one of the major characteristics qualifying in vitro human dendritic cells (DCs) during their generation process. Here, we report that CD1A transcription is regulated by a mechanism involving the long and short isoforms of CD99. Using a lentiviral construct encoding for a CD99 short hairpin RNA, we were able to inhibit CD99 expression in human primary DCs. In such cells, CD1a membrane expression increased and CD1A transcripts were much higher in abundance compared to cells expressing CD99 long form (CD99LF). We also show that CD1A transcription is accompanied by a switch in expression from CD99LF to expression at comparable levels of both CD99 isoforms during immature DCs generation in vitro. We demonstrate that CD99LF maintains a lower level of CD1A transcription by up-regulating the phosphorylated form of the ATF-2 transcription factor and that CD99 short form (SF) is required to counteract this regulatory mechanism. Elucidation of the molecular mechanisms related to CD99 alternative splicing will be very helpful to better understand the transcriptional regulatory mechanism of CD1a molecules during DCs differentiation and its involvement in the immune response. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Lysophospholipid presentation by CD1d and recognition by a human Natural Killer T-cell receptor

    Energy Technology Data Exchange (ETDEWEB)

    López-Sagaseta, Jacinto; Sibener, Leah V.; Kung, Jennifer E.; Gumperz, Jenny; Adams, Erin J. (UC); (UW-MED)

    2014-10-02

    Invariant Natural Killer T (iNKT) cells use highly restricted {alpha}{beta} T cell receptors (TCRs) to probe the repertoire of lipids presented by CD1d molecules. Here, we describe our studies of lysophosphatidylcholine (LPC) presentation by human CD1d and its recognition by a native, LPC-specific iNKT TCR. Human CD1d presenting LPC adopts an altered conformation from that of CD1d presenting glycolipid antigens, with a shifted {alpha}1 helix resulting in an open A pocket. Binding of the iNKT TCR requires a 7-{angstrom} displacement of the LPC headgroup but stabilizes the CD1d-LPC complex in a closed conformation. The iNKT TCR CDR loop footprint on CD1d-LPC is anchored by the conserved positioning of the CDR3{alpha} loop, whereas the remaining CDR loops are shifted, due in part to amino-acid differences in the CDR3{beta} and J{beta} segment used by this iNKT TCR. These findings provide insight into how lysophospholipids are presented by human CD1d molecules and how this complex is recognized by some, but not all, human iNKT cells.

  11. Multi-Objective Resource Allocation Scheme for D2D Multicast with QoS Guarantees in Cellular Networks

    Directory of Open Access Journals (Sweden)

    Fangmin Li

    2016-09-01

    Full Text Available Device-to-device (D2D multicast communication can greatly improve the spectrum utilization in a content delivery scenario. However, the co-channel interference and power consumption brought by D2D bring new challenges. All the D2D multicast groups expect to achieve a higher system capacity with less extra energy cost. In this paper, we investigate the uplink resource allocation issue when D2D multicast groups share the resources with other cellular uses (CUs, while guaranteeing a certain level of quality of service (QoS to CUs and D2D users. Firstly we address a flexible tradeoff framework in which the system power consumption and the system capacity (i.e., the number of admitted D2D links are assigned with different weight factors so that these two objectives are jointly considered. Then we propose an efficient resource optimization scheme, which comprises sub-channel allocation and signal-to-interference- plus-noise ratio (SINR assignment. Numerical results validate the effectiveness of the proposed framework, and demonstrate the advantages in dealing with the proposed multi-objective optimization problem.

  12. Research and Analysis on Multicasting in Wireless Mesh Networks%无线Mesh网络组播研究分析

    Institute of Scientific and Technical Information of China (English)

    张萌; 宋建新

    2011-01-01

    In this paper,a survey on multicast protocols in Wireless Mesh Network (WMN) is presented. And factors to be addressed while designing a multicast protocol for wireless mesh network all also analyzed,like availability of mesh router infrastructure,effect of multiple channels and channel assignment,load balancing,selection of multicast routing metric,effect of guaranteed QoS,and cross layer optimization. Finally,the problems in current research are discussed,and the new point of views on the future research are given.%介绍了无线Mesh网络(WMN)中的组播协议,并分析了为WMN设计组播协议时要注意的一些因素,如Mesh路由器的有效性、多信道和信道分配的影响、负载均衡、组播路由性能指标的选择、保证QoS的影响和跨层优化.最后,分析了目前研究中存在的问题,并对未来的研究提出了自己的看法.

  13. 多点通信中的可靠性机制%On the Mechanism of Reliable Multicast

    Institute of Scientific and Technical Information of China (English)

    刘越; 张宝贤; 陈常嘉

    2000-01-01

    多点通信可以实现组成员之间迅速有效的信息交换.可靠性是多点通信研究中的一个重要问题,其实现机制与点到点方式中有所不同.分析了多点通信可靠性方面所提出的新问题和解决方法,并简要介绍了一个实用性协议.

  14. Design and Performance Evaluation of Cooperative Retransmission Scheme for Reliable Multicast Services in Cellular Controlled P2P Networks

    DEFF Research Database (Denmark)

    Zhang, Qi; Fitzek, F.H.P.; Iversen, Villy Bæk

    2007-01-01

    communication architecture. It is referred to as cellular controlled peer-to- peer network, where the mobile devices communicate directly with each other to perform cooperative retransmissions using their short-range communication capabilities in addition to their cellular links. Based on the cooperative...... architecture a novel retransmission scheme is proposed exploiting the short-range retransmission in this paper. The state of the art, the non-cooperative error recovery schemes (e.g., ARQ, Layered FEC and Integrated FEC II) and the proposed scheme are compared with each other in terms of energy consumption...... to show the benefit of the newly introduced scheme....

  15. Connecting Anxiety and Genomic Copy Number Variation: A Genome-Wide Analysis in CD-1 Mice.

    Directory of Open Access Journals (Sweden)

    Julia Brenndörfer

    Full Text Available Genomic copy number variants (CNVs have been implicated in multiple psychiatric disorders, but not much is known about their influence on anxiety disorders specifically. Using next-generation sequencing (NGS and two additional array-based genotyping approaches, we detected CNVs in a mouse model consisting of two inbred mouse lines showing high (HAB and low (LAB anxiety-related behavior, respectively. An influence of CNVs on gene expression in the central (CeA and basolateral (BLA amygdala, paraventricular nucleus (PVN, and cingulate cortex (Cg was shown by a two-proportion Z-test (p = 1.6 x 10-31, with a positive correlation in the CeA (p = 0.0062, PVN (p = 0.0046 and Cg (p = 0.0114, indicating a contribution of CNVs to the genetic predisposition to trait anxiety in the specific context of HAB/LAB mice. In order to confirm anxiety-relevant CNVs and corresponding genes in a second mouse model, we further examined CD-1 outbred mice. We revealed the distribution of CNVs by genotyping 64 CD 1 individuals using a high-density genotyping array (Jackson Laboratory. 78 genes within those CNVs were identified to show nominally significant association (48 genes, or a statistical trend in their association (30 genes with the time animals spent on the open arms of the elevated plus-maze (EPM. Fifteen of them were considered promising candidate genes of anxiety-related behavior as we could show a significant overlap (permutation test, p = 0.0051 with genes within HAB/LAB CNVs. Thus, here we provide what is to our knowledge the first extensive catalogue of CNVs in CD-1 mice and potential corresponding candidate genes linked to anxiety-related behavior in mice.

  16. Self-regressing S100-negative CD1a-positive cutaneous histiocytosis.

    Science.gov (United States)

    Tardío, Juan C; Aguado, Marta; Borbujo, Jesús

    2013-06-01

    In the skin, the antigen-presenting cells are mainly represented by Langerhans cells, indeterminate cells, and interstitial dendritic cells, which show distinctive immunophenotype and/or ultrastructure. We report a case of a cutaneous-limited self-regressing histiocytosis with a peculiar immunohistochemical profile (CD1a-positive and S100 protein-negative) that is not observed in any of the known cutaneous antigen-presenting cell or nowadays recognized neoplasm. This lesion is probably related to indeterminate dendritic cell tumors, but very few cases with such immunoprofile have been reported up-to-date, and their exact nosologic position and outcome remain to be clarified.

  17. Synthesis and Optical Properties of ZnxCd1-xS :Ag Nanocrystals%ZnxCd1-xS:Ag纳米晶的合成及其光学性质研究

    Institute of Scientific and Technical Information of China (English)

    戴洁; 菅文平; 庄家骐; 杨文胜

    2006-01-01

    以巯基丙酸(MPA)为稳定剂,利用共沉淀法制备了水溶性的Ag掺杂的ZnxCd1-xS合金型纳米晶.Ag掺杂后ZnxCd1-xS纳米晶产生新的发射峰,并且发光效率得到了有效提高.通过改变纳米粒子中Zn/Cd比例可有效地调控ZnxCd1-xS :Ag纳米晶的吸收带隙宽度,同时可以在425~603 nm之间实现对ZnxCd1-xS :Ag纳米晶发射峰位的连续调控.

  18. INFORMATION TRANSMISSION BASED ON MULTICAST TECHNOLOGY%基于组播技术的信息传递

    Institute of Scientific and Technical Information of China (English)

    诸坚彬; 秦会斌; 崔佳冬; 秦利红; 曹曙光

    2016-01-01

    针对在局域网中,发送方无法传递信息给不在同一局域网内的第三方。提出一种通过组播技术传递信息给第三方的方法。在这种方法中,发送方将信息隐藏于组播包的 MAC 地址中,然后把这些组播包通过 WiFi 发送出去,第三方使用无线网络抓包技术得到这些组播包,通过分析组播包的 MAC 地址解析出原始信息。该方法能够实现类似 TI(Texas Instruments)的 smart config 技术。在实验中,通过与 TI 使用的方法作对比,表明这种方法明显减少了所用网络数据包的数量,耗时也大大减少,同时使信息易于解析,效率得到了很大的提高。%We proposed a method that transfers information to a third party using multicast technology,thus solves the problem that the sender in a local area network (LAN)cannot pass the information onto a third party not in same LAN.In this method,the sender hides the information in MAC address of multicast packets,and then sends these multicast packets out through WiFi,the third party gets these multicast packets by wireless network packet capture,and figures out the original information by analysing the MAC address of multicast packets.This method can implement the technique similar to smart config of TI (Texas Instruments).In experiment,by comparing it with the method the TI using,we found that this one noticeably decreased the amount of packets used in the network and reduced the time consumption as well, meanwhile it also made the information easy to be figured out,and greatly improved the efficiency.

  19. WDM光网络中多播业务量疏导方法分析%Analysis of multicast traffic grooming algorithms in WDM mesh networks

    Institute of Scientific and Technical Information of China (English)

    刘焕淋; 方强; 雷芳

    2012-01-01

    在光层多播树路由中疏导低速业务实现阻塞率降低和吞吐量提高是光网络比较复杂的联合优化问题.分析了WDM(wave-length division multiplex)网络中多播业务量疏导问题的研究方法和成果,分析比较了静态多播业务和动态多播业务的疏导方法,并讨论了各种多播业务疏导方法性能、特点及存在的问题,最后总结了关于动态多播疏导的未来研究思路.%Grooming the low-speed traffic to reduce the blocking probability and improve throughput in optical layer multicast routing tree is a more complex joint optimization problem. The paper analyzes the methods and results of the optical multicast traffic grooming problem in WDM networks. Also,the multicast static traffic and dynamic traffic grooming algorithms are analyzed and compared in the paper respectively. Furthermore,the authors discuss the performance,characteristics and the existing problems of those algorithms for optical multicast traffic grooming. Finally,we summarize the future research ideas about the methods of dynamic multicast traffic grooming.

  20. An ECN-Based Bandwidth Sharing Algorithm for Unicast and Multicast Flows%基于ECN的单播流与多播流间带宽共享算法

    Institute of Scientific and Technical Information of China (English)

    杨明; 张福炎

    2003-01-01

    An ECN-based implementing bandwidth-sharing algorithm for unicast and multicast flows is presented.The algorithm uses a bandwidth allocation strategy to give an incentive to multicast flows in bandwidth allocation according to algorithm of the number of receivers, and to assure the unicast flows get their bandwidth shares fairly.Provided best-effort networks, an ECN-based congestion control algorithm is used to implement differentiated service in bandwidth allocation between unicast flows and multicast flows. In implementation, we solve the problems such asreceiver's number estimation, the RTT estimation and compromise between convergence and stability.The simulation results show that the algorithm can implement bandwidth sharing for TCP flows and multicast flows. Atthe same time, the algorithm not only allocates more bandwidth to multicast flows, but promises TCP flows to get their fair bandwidth share.

  1. CD1d expression and invariant NKT cell responses in herpesvirus infections

    Directory of Open Access Journals (Sweden)

    Rusung eTan

    2015-06-01

    Full Text Available Invariant natural killer T (iNKT cells are a highly conserved subset of unconventional T lymphocytes that express a canonical, semi-invariant T cell receptor (TCR and surface markers shared with the natural killer cell lineage. iNKT cells recognize exogenous and endogenous glycolipid antigens restricted by non-polymorphic CD1d molecules, and are highly responsive to the prototypical agonist, α-galactosylceramide. Upon activation, iNKT cells rapidly coordinate signaling between innate and adaptive immune cells through the secretion of proinflammatory cytokines, leading to the maturation of antigen-presenting cells and expansion of antigen-specific CD4+ and CD8+ T cells. Because of their potent immunoregulatory properties, iNKT cells have been extensively studied and are known to play a pivotal role in mediating immune responses against microbial pathogens including viruses. Here, we review evidence that herpesviruses manipulate CD1d expression to escape iNKT cell surveillance and establish lifelong latency in humans. Collectively, published findings suggest that iNKT cells play critical roles in anti-herpesvirus immune responses and could be harnessed therapeutically to limit viral infection and viral-associated disease.

  2. Twinning in vapour-grown, large volume Cd1-xZnxTe crystals

    Science.gov (United States)

    Tanner, B. K.; Mullins, J. T.; Pym, A. T. G.; Maneuski, D.

    2016-08-01

    The onset of twinning from (2 bar 1 bar 1 bar) to (1 bar 3 bar 3 bar) in large volume Cd1-xZnxTe crystals, grown by vapour transport on (2 bar 1 bar 1 bar) , often referred to as (211)B, oriented GaAs seeds, has been investigated using X-ray diffraction imaging (X-ray topography). Twinning is not associated with strains at the GaAs/CdTe interface as the initial growth was always in (2 bar 1 bar 1 bar) orientation. Nor is twinning related to lattice strains associated with injection of Zn subsequent to initial nucleation and growth of pure CdTe as in both cases twinning occurred after growth of several mm length of Cd1-xZnxTe. While in both cases examined, there was a region of disturbed growth prior to the twinning transition, in neither crystal does this strain appear to have nucleated the twinning process. In both cases, un-twinned material remained after twinning was observed, the scale of the resulting twin boundaries being sub-micron. Simultaneous twinning across the whole sample surface was observed in one sample, whereas in the other, twinning was nucleated at different points and times in the growth.

  3. Inhibitory avoidance in CD1 mice: sex matters, as does the supplier.

    Science.gov (United States)

    Parra, Andrés; Rama, Encarnación; Vinader-Caerols, Concepción; Monleón, Santiago

    2013-11-01

    The purpose of the present work was to study possible differences in the learning of inhibitory avoidance (also called passive avoidance) in male and female CD1 mice acquired from three different suppliers, for which a one-trial step-through version of the paradigm was employed. Ninety-six mice from Charles River (France), Janvier (France) and Harlan (The Netherlands) laboratories were divided by sex and assigned to group C, J or H, respectively (n=16). The animals were tested in the training phase (foot-shock: 0.3mA, 5s) and again for avoidance (no foot-shock delivered) one week later. Inhibitory avoidance learning (test latencies significantly higher than training latencies) was observed in every one of the six groups of animals. The variable Supplier was statistically significant, showing better to worse avoidance in C, J and H mice (in that order). A post hoc analysis showed differences between groups C and H. Females tended to exhibit avoidance learning to a greater extent than males. Our results suggest that inhibitory avoidance learning in CD1 mice varies depending on the breeding facilities from which they originate, and that females should be included in inhibitory avoidance studies.

  4. Endogenous collagen peptide activation of CD1d-restricted NKT cells ameliorates tissue-specific inflammation in mice

    DEFF Research Database (Denmark)

    Liu, Yawei; Teige, Anna; Mondoc, Emma

    2011-01-01

    suppressed a range of in vivo inflammatory conditions, including delayed-type hypersensitivity, antigen-induced airway inflammation, collagen-induced arthritis, and EAE, which were all ameliorated by mCII707-721 vaccination. The findings presented here offer new insight into the intrinsic roles of NKT cells......NKT cells in the mouse recognize antigen in the context of the MHC class I-like molecule CD1d and play an important role in peripheral tolerance and protection against autoimmune and other diseases. NKT cells are usually activated by CD1d-presented lipid antigens. However, peptide recognition...... in the context of CD1 has also been documented, although no self-peptide ligands have been reported to date. Here, we have identified an endogenous peptide that is presented by CD1d to activate mouse NKT cells. This peptide, the immunodominant epitope from mouse collagen type II (mCII707-721), was not associated...

  5. Elevated and cross-responsive CD1a-reactive T cells in bee and wasp venom allergic individuals.

    Science.gov (United States)

    Subramaniam, Sumithra; Aslam, Aamir; Misbah, Siraj A; Salio, Mariolina; Cerundolo, Vincenzo; Moody, D Branch; Ogg, Graham

    2016-01-01

    The role of CD1a-reactive T cells in human allergic disease is unknown. We have previously shown that circulating CD1a-reactive T cells recognize neolipid antigens generated by bee and wasp venom phospholipase, and here tested the hypothesis that venom-responsive CD1a-reactive T cells associate with venom allergy. Circulating T cells from bee and wasp venom allergic individuals, before and during immunotherapy, were exposed to CD1a-transfected K562 cells in the presence of wasp or bee venom. T-cell response was evaluated based on IFNγ, GM-CSF, and IL-13 cytokine production. Venom allergic individuals showed significantly higher frequencies of IFN-γ, GM-CSF, and IL-13 producing CD1a-reactive T cells responsive to venom and venom-derived phospholipase than healthy individuals. Venom-responsive CD1a-reactive T cells were cross-responsive between wasp and bee suggesting shared pathways of allergenicity. Frequencies of CD1a-reactive T cells were initially induced during subcutaneous immunotherapy, peaking by weeks 5, but then reduced despite escalation of antigen dose. Our current understanding of venom allergy and immunotherapy is largely based on peptide and protein-specific T cell and antibody responses. Here, we show that lipid antigens and CD1a-reactive T cells associate with the allergic response. These data have implications for mechanisms of allergy and approaches to immunotherapy. © 2015 The Authors. European Journal of Immunology published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Optical properties of Cd1-xZnxTe films in a device structure using variable angle spectroscopic ellipsometry

    Science.gov (United States)

    Paulson, P. D.; McCandless, B. E.; Birkmire, R. W.

    2004-03-01

    The optical properties of polycrystalline Cd1-xZnxTe alloy thin films in device structures are reported for energy from 0.8 to 4.6 eV. Cd1-xZnxTe alloy thin films with x from 0 to 1 were deposited on glass/indium-tin-oxide (ITO)/CdS substrates by coevaporation from CdTe and ZnTe sources and were characterized by variable angle spectroscopic ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffractometry. The Cd1-xZnxTe films are single phase with a zincblende crystal structure over the entire alloy range. The Cd1-xZnxTe optical constants were determined using a multilayer optical model incorporating the optical constants of glass, ITO and CdS, determined independently from glass, glass/ITO, and glass/ITO/CdS specimens. The optical constants of the Cd1-xZnxTe thin films are comparable to literature values reported for single crystals, indicating that the polycrystalline nature of the films does not measurably alter the optical constants. A semiconductor alloy model for determining the composition of CdxZn1-xTe alloy films is developed using the optical data obtained from the analysis. This alloy model can be used to evaluate compositional grading and the effects of Cd1-xZnxTe film processing.

  7. Microwave-assisted synthesis of Zn x Cd1- x S-MWCNT heterostructures and their photocatalytic properties

    Science.gov (United States)

    Wu, Huaqiang; Yao, Youzhi; Li, Wenting; Zhu, Lulu; Ni, Na; Zhang, Xiaojun

    2011-05-01

    The multi-walled carbon nanotubes (MWCNTs) wrapped with hexagonal wurtzite Zn x Cd1- x S nanoparticles with a uniform and small diameter have been prepared to form Zn x Cd1- x S-MWCNT heterostructures by microwave-assisted route using Zn(Ac)2, Cd(NO3)2, and thioacetamide as the reactants. The heterostructures have been characterized by X-ray powder diffraction, scanning and transmission electron microscopy, high-resolution transmission electron microscopy, photoluminescence (PL) and PL excited lifetime. Despite the analogous size and configuration, the Zn x Cd1- x S-MWCNT ( x = 0, 0.2, 0.5, 0.8, 1) with different Zn concentration exhibit composition-dependent absorption properties in the visible zone. The PL peak positions of Zn x Cd1- x S-MWCNT change gradually from ZnS-MWCNT to CdS-MWCNT. The Zn x Cd1- x S-MWCNT shows different photocatalytic activity towards the photodegradation of fuchsin acid under visible light illumination, photocatalytic activity of the Zn x Cd1- x S-MWCNT decreases gradually with the increase in the Zn concentration, the Zn0.2Cd0.8S-MWCNT possessed the best photocatalytic activity. After recycling thrice, the photocatalysts still have about 85% efficiency.

  8. Reliability Engineering

    CERN Document Server

    Lazzaroni, Massimo

    2012-01-01

    This book gives a practical guide for designers and users in Information and Communication Technology context. In particular, in the first Section, the definition of the fundamental terms according to the international standards are given. Then, some theoretical concepts and reliability models are presented in Chapters 2 and 3: the aim is to evaluate performance for components and systems and reliability growth. Chapter 4, by introducing the laboratory tests, puts in evidence the reliability concept from the experimental point of view. In ICT context, the failure rate for a given system can be

  9. All-Optical 1-to-8 Wavelength Multicasting at 20 Gbit/s Exploiting Self-Phase Modulation in Dispersion Flattened Highly Nonlinear Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    Zhan-Qiang Hui

    2014-01-01

    Full Text Available All-optical multicasting of performing data routing from single node to multiple destinations in the optical domain is promising for next generation ultrahigh-peed photonic networks. Based on the self-phase modulation in dispersion flattened highly nonlinear photonic crystal fiber and followed spectral filtering, simultaneous 1-to-8 all-optical wavelength multicasting return-to-zero (RZ signal at 20 Gbit/s with 100 GHz channel spaced is achieved. Wavelength tunable range and dynamic characteristic of proposed wavelength multicasting scheme is further investigated. The results show our designed scheme achieve operation wavelength range of 25 nm, OSNR of 32.01 dB and Q factor of 12.8. Moreover, the scheme has simple structure as well as high tolerance to signal power fluctuation.

  10. Znx Cd1-x S的可控合成及其光学性质的研究%Controllable Preparation of ZnxCd1-xS and Investigation of Its Study of Optical Property

    Institute of Scientific and Technical Information of China (English)

    崔华楠; 石建英; 戚小莺

    2011-01-01

    The composition-tunable ZnxCd1-xS compounds were prepared by a facile and mild approach involved in polylol refluxing processes. Their structures were characterized using X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses. The optical properties of ZnxCd1-xS were studied by UV-vis and photoluminescence (PL) spectroscopy. The results indicated that the ZnxCd1-xS compounds exhibited as the wurtzite structure and their particle size decreased with the increase of Zn content. The composition-dependence optical properties were observed for all ZnxCd1-xS compounds. Both the absorption and luminescence band systematically shifted from the longer wavelength for CdS to the shorter wavelength for ZnS.%采用多元醇回流法,合成了组成可调的ZnxCd1-xS纳米材料,采用透射电镜(TEM)及X射线粉末衍射(XRD)表征了样品的结构特征,并通过紫外-可见吸收(UV-Vis)和光致发光(PL)光谱对样品进行了光学性质的研究.文章所用的合成方法具有简单、快速、经济、条件温和等特点,所得ZnxCd1-xS具有六方纤锌矿结构,粒径在5 ~20 nm左右,并且ZnxCd1-xS呈现出随组成改变而连续调变的光学性质.

  11. Investigating the effects of nanoparticles on reproduction and development in Drosophila melanogaster and CD-1 mice

    Science.gov (United States)

    Philbrook, Nicola Anne

    Manufactured nanoparticles (NPs) are a class of small (≤ 100 nm) materials that are being used for a variety of purposes, including industrial lubricants, food additives, antibacterial agents, as well as delivery systems for drug and gene therapies. Their unique characteristics due to their small size as well as their parent materials allow them to be exploited in convenience applications; however, some of these properties also allow them to interact with and invade biological systems. Few studies have been performed to determine the potential harm that NPs can inflict on reproductive and developmental processes in organisms. In this study, Drosophila melanogaster and CD-1 mice were orally exposed to varying doses of titanium dioxide (TiO 2) NPs, silver (Ag) NPs, or hydroxyl-functionalized carbon nanotubes (fCNTs) and Drosophila were also exposed to microparticles (MPs) as a control for particle size. The subsequent effect of these materials on reproduction and development were evaluated. Strikingly, each type of NP studied negatively affected either reproduction or development in one or both of the two model systems. TiO2 NPs significantly negative effected both CD-1 mouse development (100 mg/kg or 1000 mg/kg) as well as Drosophila female fecundity (0.005%-0.5% w/v). Ag NPs significantly reduced mouse fetus viability after prenatal exposure to10 mg/kg. Ag NPs also significantly decreased the developmental success of Drosophila when they were directly exposed to these NPs (0.05% - 0.5% w/v) compared to both the vehicle and MP controls. fCNTs significantly increased the presence of morphological defects, resorptions and skeletal abnormalities in CD-1 mice, but had little effect on Drosophila. We speculate that the differences seen in the effects of NP types may be partially due to differences in reproductive physiology as well as each organism's ability to internalize these NPs. Whereas the differing response of each organism to a NP type was likely due in part to

  12. TLR9-induced miR-155 and Ets-1 decrease expression of CD1d on B cells in SLE.

    Science.gov (United States)

    Liu, Fei; Fan, Hongye; Ren, Deshan; Dong, Guanjun; Hu, Erling; Ji, Jianjian; Hou, Yayi

    2015-07-01

    B cells present lipid antigens to CD1d-restricted invariant natural killer T (iNKT) cells to maintain autoimmune tolerance, and this process is disrupted in systemic lupus erythematosus (SLE). Inflammation may inhibit CD1d expression to exacerbate the pathology of lupus. However, how inflammation regulates CD1d expression on B cells is unclear in SLE. In the present study, we showed that the surface expression of CD1d on B cells from SLE mice was decreased and that stimulation of inflammatory responses through TLR9 decreased the membrane and total CD1d levels of CD1d on B cells. Moreover, inflammation-related microRNA-155 (miR-155) negatively correlated with the expression of CD1d in B cells. miR-155 directly targeted the 3'-untranslated region (3'-UTR) of CD1d upon TLR9 activation in both humans and mice. The inhibitory effects of miR-155 on CD1d expression in B cells impaired their antigen-presenting capacity to iNKT cells. In addition, Ets-1, a susceptibility gene of SLE, also directly regulated the expression of the CD1d gene at the transcriptional level. These findings provide new insight into the mechanism underlying decreased CD1d expression on B cells in SLE, suggesting that inhibition of inflammation may increase CD1d expression in B cells to ameliorate SLE via modulating iNKT cells.

  13. 一种动态的单组播集成调度算法%Dynamic Integrated Schedule Algorithm of Unicast and Multicast

    Institute of Scientific and Technical Information of China (English)

    任涛; 兰巨龙; 扈红超

    2011-01-01

    Most existing integrated unicast and multicast schedule algorithms can not keep high throughput when the ratio of unicast and multicast traffic changes, a dynamic integrated schedule algorithm of unicast and multicast is proposed. The algorithm is designed based on Input Queued(IQ) switch which is used widely. By monitoring the ratio of unicast and multicast traffic of the latest several time slots at the input port, it dynamically decides the integrated schedule scheme of unicast and multicast. Simulation results show that the unicast throughput, multicast throughput and overall throughput of the proposed algorithm are always higher than that of FILM and fSCIA, and the overall average delay of the proposed algorithm is also the best.%在单组播比例发生变化的情况下,现有单组播集成调度算法无法保持较高吞吐率.针对该问题,提出一种动态的单组播集成调度算法.基于输入排队(IQ)的交换结构,通过在输入端口处监测最近若干个时隙的单组播业务输入情况,动态决定当前的单组播集成调度策略.仿真结果表明,该算法的单播吞吐率、组播吞吐率和总体吞吐率均高于FILM算法和fSCIA算法,并具有较好的时延性能.

  14. Intramolecular electron transfer in cytochrome cd(1) nitrite reductase from Pseudomonas stutzeri; kinetics and thermodynamics

    DEFF Research Database (Denmark)

    Farver, Ole; Kroneck, Peter M H; Zumft, Walter G

    2002-01-01

    , internal electron transfer between these sites is an inherent element in the catalytic cycle of this enzyme. We have investigated the internal electron transfer reaction employing pulse radiolytically produced N-methyl nicotinamide radicals as reductant which reacts solely with the heme-c in an essentially...... diffusion controlled process. Following this initial step, the reduction equivalent is equilibrating between the c and d(1) heme sites in a unimolecular process (k=23 s(-1), 298 K, pH 7.0) and an equilibrium constant of 1.0. The temperature dependence of this internal electron transfer process has been......Cytochrome cd(1) nitrite reductase from Pseudomonas stutzeri catalyzes the one electron reduction of nitrite to nitric oxide. It is a homodimer, each monomer containing one heme-c and one heme-d(1), the former being the electron uptake site while the latter is the nitrite reduction site. Hence...

  15. Role of CD1A and HSP60 in the antitumoral response of oesophageal cancer

    Directory of Open Access Journals (Sweden)

    Giovanni Zummo

    2011-12-01

    Full Text Available Oesophageal cancer (OC is one of the most common and severe forms of tumor. A wider knowledge of molecular mechanisms which lead to a normal epithelium becoming a neoplasm may reveal new strategies to improve treatment and outcome of this disease. In this review, we report recent findings concerning molecular events which take place during carcinogenesis of the oesophagus. In particular, we focus on the role of two molecules, CD1a and Hsp60, which are overexpressed in oesophageal and many other types of tumor. Both molecules may present tumor antigens and promote in situ the stimulation of an antitumoral immune activity. We suggest there is a synergistic action between these molecules. Further knowledge about their intracellular pathways and extracellular roles may help develop new antitumoral tools for OC.

  16. Optical fiber temperature sensor utilizing alloyed Zn(x)Cd(1-x)S quantum dots.

    Science.gov (United States)

    Zhao, Fei; Kim, Jongsung

    2014-08-01

    In this paper, optical fiber temperature sensors have been prepared by using alloyed Zn(x)Cd(1-x)S quantum dots as sensing media. The surface of the optical fiber was silanized to enhance covalent bond between quantum dots and optical fiber. The quantum dots were bonded to the surface of optical fiber and further encapsulated via sol-gel coating using 3-glycidoxypropyl trimethoxysilane (GPTMS) and 3-aminopropyl trimethoxysilane (APTMS) in ethyl alcohol in acidic condition. Quantum dots with green, yellow, and red fluorescence were used. The dependence of photoluminescence (PL) intensity from quantum dots on ambient temperature has been studied. Linear relation between the fluorescent intensity and temperature was obtained from alloyed quantum dots immobilized on the surface of optical fiber. The PL intensity, sensitivity, and thermal stability were increased by the silica encapsulation.

  17. Tunable Photonic RF Generator for Dynamic Allocation and Multicast of 1.25 Gbps Channels in the 60 GHz Unlicensed Band

    DEFF Research Database (Denmark)

    Lebedev, Alexander; Pang, Xiaodan; Vegas Olmos, Juan José

    2013-01-01

    We propose an approach for dynamic channel allocation and multicast data delivery inside the 60 GHz unlicensed band. Channels, conveying 1.25 Gbps signals, can be allocated on demand by tuning the frequency sweep of an external cavity laser (ECL) either in the optical remote node (RN) or in the c......We propose an approach for dynamic channel allocation and multicast data delivery inside the 60 GHz unlicensed band. Channels, conveying 1.25 Gbps signals, can be allocated on demand by tuning the frequency sweep of an external cavity laser (ECL) either in the optical remote node (RN...

  18. Simulation-Based Performance Evaluation of Predictive-Hashing Based Multicast Authentication Protocol

    Directory of Open Access Journals (Sweden)

    Seonho Choi

    2012-12-01

    Full Text Available A predictive-hashing based Denial-of-Service (DoS resistant multicast authentication protocol was proposed based upon predictive-hashing, one-way key chain, erasure codes, and distillation codes techniques [4, 5]. It was claimed that this new scheme should be more resistant to various types of DoS attacks, and its worst-case resource requirements were derived in terms of coarse-level system parameters including CPU times for signature verification and erasure/distillation decoding operations, attack levels, etc. To show the effectiveness of our approach and to analyze exact resource requirements in various attack scenarios with different parameter settings, we designed and implemented an attack simulator which is platformindependent. Various attack scenarios may be created with different attack types and parameters against a receiver equipped with the predictive-hashing based protocol. The design of the simulator is explained, and the simulation results are presented with detailed resource usage statistics. In addition, resistance level to various types of DoS attacks is formulated with a newly defined resistance metric. By comparing these results to those from another approach, PRABS [8], we show that the resistance level of our protocol is greatly enhanced even in the presence of many attack streams.

  19. Optimally Efficient Prefix Search and Multicast in Structured P2P Networks

    CERN Document Server

    Bradler, Dirk; Muehlhaeuser, Max

    2008-01-01

    Searching in P2P networks is fundamental to all overlay networks. P2P networks based on Distributed Hash Tables (DHT) are optimized for single key lookups, whereas unstructured networks offer more complex queries at the cost of increased traffic and uncertain success rates. Our Distributed Tree Construction (DTC) approach enables structured P2P networks to perform prefix search, range queries, and multicast in an optimal way. It achieves this by creating a spanning tree over the peers in the search area, using only information available locally on each peer. Because DTC creates a spanning tree, it can query all the peers in the search area with a minimal number of messages. Furthermore, we show that the tree depth has the same upper bound as a regular DHT lookup which in turn guarantees fast and responsive runtime behavior. By placing objects with a region quadtree, we can perform a prefix search or a range query in a freely selectable area of the DHT. Our DTC algorithm is DHT-agnostic and works with most exi...

  20. Interference-Aware Scheduling for Connectivity in MIMO Ad Hoc Multicast Networks

    CERN Document Server

    Jiang, Feng; Swindlehurst, A Lee

    2012-01-01

    We consider a multicast scenario involving an ad hoc network of co-channel MIMO nodes in which a source node attempts to share a streaming message with all nodes in the network via some pre-defined multi-hop routing tree. The message is assumed to be broken down into packets, and the transmission is conducted over multiple frames. Each frame is divided into time slots, and each link in the routing tree is assigned one time slot in which to transmit its current packet. We present an algorithm for determining the number of time slots and the scheduling of the links in these time slots in order to optimize the connectivity of the network, which we define to be the probability that all links can achieve the required throughput. In addition to time multiplexing, the MIMO nodes also employ beamforming to manage interference when links are simultaneously active, and the beamformers are designed with the maximum connectivity metric in mind. The effects of outdated channel state information (CSI) are taken into accoun...

  1. New Downlink Scheduling Framework for Hybrid Unicast and Multicast Traffic in WiMAX Networks

    Directory of Open Access Journals (Sweden)

    Rashid Karimi

    2012-10-01

    Full Text Available WiMAX networks based on IEEE 802.16 standard has expedited broadband wireless access surge in recent years. The traffic in these networks is identified in four types of class of service with different QoS requirements. Therefore, scheduling mechanism to manage these services in order to meet QoS requirements is a crucial fact and an important challenge. In this paper, for PMP mode of WiMAX networks, a two-level scheduling mechanism in MAC layer of Base Station (BS has been proposed. The proposed scheduling algorithm takes into account hybrid unicast and multicast downlink traffic including three classes of service: rtps, nrtps and BE. In the first level of this scheduling mechanism, we have used the scheduling algorithms WRR and FCFS to schedule the connections and in its second level, the PQ algorithm based on Aging method is used to manage and schedule the packets. The functionality of the proposed scheduling algorithm is compared with priority queuing (PQ algorithm. The resulting outcome of simulation shows that the proposed design has quite a better performance for Best Effort (BE service class. Furthermore the delay of the rtps class and total throughput of the network is increased noticeably

  2. Performance of QoS-based multicast routing algorithms for real-time communication

    Science.gov (United States)

    Verma, Sanjeev; Pankaj, Rajesh K.; Leon-Garcia, Alberto

    1997-10-01

    In recent years, there has been a lot of interest in providing real-time multimedia services like digital audio and video over packet-switched networks such as Internet and ATM. These services require certain quality of service (QoS) from the network. The routing algorithm should take QoS factor for an application into account while selecting the most suitable route for the application. In this paper, we introduce a new routing metric and use it with two different heuristics to compute the multicast tree for guaranteed QoS applications that need firm end-to-end delay bound. We then compare the performance of our algorithms with the other proposed QoS-based routing algorithms. Simulations were run over a number of random networks to measure the performance of different algorithms. We studied routing algorithms along with resource reservation and admission control to measure the call throughput over a number of random networks. Simulation results show that our algorithms give a much better performance in terms of call throughput over other proposed schemes like QOSPF.

  3. Pulmonary toxicity and metabolic activation of dauricine in CD-1 mice.

    Science.gov (United States)

    Jin, Hua; Dai, Jieyu; Chen, Xiaoyan; Liu, Jia; Zhong, Dafang; Gu, Yansong; Zheng, Jiang

    2010-03-01

    Dauricine is the major bioactive component isolated from the roots of Menispermum dauricum D.C. and has shown promising pharmacological activities with a great potential for clinic use. However, the adverse effects and toxicity of the alkaloid are unfortunately ignored. The objective of the current study was to evaluate the toxicity of dauricine in vitro and in vivo. Mice (CD-1) were treated intraperitoneally with dauricine at various doses, and sera and lung lavage fluids were collected after 24 h of treatment. No changes in serum aspartate aminotransferase, alanine aminotransferase, and blood urea nitrogen were noticed, whereas a dose-dependent increase in lactate dehydrogenase activity was observed in lung lavage fluids. Ethidium-based staining studies showed that remarkable cells lost membrane integrity in the lungs of the animals treated with dauricine at 150 mg/kg. Histopathological evaluation of lungs of mice showed that dauricine at the same dose caused significant alveolar edema and hemorrhage. Exposure to dauricine at 40 muM for 24 h resulted in up to 60% cell death in human lung cell lines BEAS-2B, WI-38, and A549. Ketoconazole showed protective effect on the pulmonary injury in mice given dauricine. A quinone methide metabolite of dauricine was identified in mouse lung microsomal incubations, and the presence of ketoconazole in the microsomal incubations suppressed the formation of the quinone methide metabolite. In conclusion, dauricine produced pulmonary injury in CD-1 mice. The pulmonary toxicity appears to depend on the metabolism of dauricine mediated by CYP3A. The electrophilic quinone methide metabolite probably plays an important role in the pulmonary toxicity induced by dauricine.

  4. The haemotoxicity of azathioprine in repeat dose studies in the female CD-1 mouse.

    Science.gov (United States)

    Molyneux, Gemma; Gibson, Frances M; Chen, Christabelle M; Marway, Harpal K; McKeag, Sean; Mifsud, Charles V J; Pilling, Andrew M; Whayman, Matthew J; Turton, John A

    2008-04-01

    Azathioprine (AZA) is a cytotoxic immunosuppressive drug used in the prevention of rejection in organ transplants and the treatment of auto-immune diseases. However, AZA is haemotoxic causing significant bone marrow depression. The present studies were to characterize the haemotoxicity of AZA in the female CD-1 mouse. In Experiment 1, a dose-ranging study, with AZA gavaged daily for 10 days, clinical evidence of toxicity was evident at 125 mg/kg and above. Experiment 2 was a dose-response study with AZA gavaged daily for 10 days at 40-120 mg/kg. At day 1 after the final dose, AZA induced a dose-related pancytopaenia, reduced femoral marrow cellularity, increases in serum levels of the cytokine fms-like tyrosine kinase 3 ligand, reduction in granulocyte-monocyte colony-forming units and erythroid colonies, and increased bone marrow apoptosis. Histology demonstrated hepatocyte hypertrophy, thymic atrophy, reduced splenic extramedullary haemopoiesis, and reduced cellularity of sternal bone marrow. In Experiment 3, AZA was dosed for 10 days at 100 mg/kg with autopsies at 1, 3, 9, 22, 29, 43 and 57 days postdosing. At 1, 3 and 9 days, haematological parameters reflected changes in Experiment 2. At 22/29 days, many blood parameters were returning towards normal; at 43/57 days, most parameters compared with controls. However, there was some evidence of a persistent (i.e. residual/late-stage) mild reduction in RBC and erythroid progenitor cell counts at day 43/57. We conclude that the CD-1 mouse provides an acceptable model for the haemotoxicity of AZA in man.

  5. Immunohistochemical analysis of Langerhans cells in chronic gingivitis using anti-CD1a antibody

    Directory of Open Access Journals (Sweden)

    Shweta Jaitley

    2014-01-01

    Full Text Available Background: The Langerhans cells (LCs are dendritic cells (DCs which belong to the group of antigen presenting cells (APCs. Their function is to recognize the antigen, capture it, and present it to the T lymphocytes; thus initiating an early immune response. The antigen presenting functional LCs may play an important part in initiation and development of gingivitis. The aim of this study was to analyze the density, intraepithelial distribution, and morphology of LCs in gingival epithelium among different age groups with chronic gingivitis and to compare it with that of normal gingiva. Materials and Methods: Immunohistochemistry (IHC was performed to study LCs in normal gingival epithelium (n = 10 and gingival epithelium in chronic gingivitis (n = 30 using anti-CD1a antibody. Mann Whitney U test was performed to compare the density of LCs in normal gingiva with chronic gingivitis. The distribution of LCs in various layers of the epithelium within the three age groups was analyzed using Kruskal-Wallis test. P value less than 0.05 was considered as significant. Results: The density of LCs in chronic gingivitis was significantly higher then that of normal gingiva. Comparing different age groups, the younger individuals had more number of LCs which were located in the superficial layers of gingival epithelium. In chronic gingivitis, higher number of LCs were located in deeper layers when compared with that of normal gingiva. Three morphological types of CD1a positive LCs were observed in normal gingiva, out of which the density of LCs with branched dendritic processes was highest in normal gingiva. Conclusion: The LCs showed variable number, location, and morphology which indicated their adaptation for function in chronic gingivitis.

  6. Distant exchange interactions in Cd1-xMnxS from magnetization steps method

    Science.gov (United States)

    Gratens, X.; Chitta, V.

    2017-07-01

    Three new distant neighbor (DN) antiferromagnetic exchange constants have been measured in wurtzite Cd1-xMnxS (x = 0.0087 and x = 0.0278) using the magnetization steps method in the millikelvin regime. The second (J(2)), third (J(3)), and fourth (J(4)) largest exchange constants (after the two first neighbor exchange interactions J1 and J1' ) have been measured. The results are J(2) = 300 ± 10 mK, J(3) = 173 ± 10 mK, and J(4) = 55 ± 10 mK. No significant change of the exchange constant values has been observed as a function of the Mn concentration. The mapping of the DN exchange interactions has been investigated within a sphere of radius 2 times the nearest neighbors distance. The only way to identify the J constants was using the number coordination Zn of the different DN classes: J(2) is associated to DN classes with Zn = 6, J(3) with Zn = 12, and J(4) is ascribed to a group of three DN classes with J values around J(4). The magnitude of the J constants is not in agreement with theoretical predictions of the monotonic decrease of the exchange constant with increasing distance. The present results are similar to those obtained for Cd1-xMnxSe but are different from the ones obtained for Zn1-xMnxO. The present work confirms the long-range character of the DN exchange interactions in the wurtzite type Mn-based II-VI diluted magnetic semiconductors.

  7. 利他驱动的应用层组播%Altruism Driven Application-Layer Multicast

    Institute of Scientific and Technical Information of China (English)

    王淼; 彭鸽; 张玉军; 李国杰

    2011-01-01

    节点自私问题是目前应用层组播技术面临的挑战之一.自私节点可能有意或者无意地停止转发某些数据包,导致流媒体质量下降.为了解决应用层组播中节点自私性问题,提出了一种利他驱动的应用层组播,简称ADALM机制.ADALM根据一个节点对其他节点的转发贡献,计算出该节点的利他值;基于利他值构造组播树,使得利他值较大的节点位于树的较高层.和本领域其他研究相比,ADALM在利他值计算和组播树构造方面均有创新:首先,利他值基于父亲节点和孩子节点的反馈,使得系统可以有效地检测出自私节点;节点无需发送额外的探测包去测量其邻居节点的服务质量;在组播树的构造和维护过程中,仅需要调整O(1g N)个节点;最后,利他值计算和组播树构造采用分布式方法来实现.仿真结果表明,即使存在一定比例的自私节点,ADALM也能构造一棵高性能的组播树,并且具有较低的控制负荷.%Selfishness issue is one of big challenges of current application-layer multicast techniques.The selfish participants might stop forwarding data accidentally or deliberately, which will affect the overall streaming quality. To address the selfishness issue in the application-layer multicast, an altruism driven application-layer multicast (ADALM) is presented. ADALM defines an altruism value for each node associative to its contributions to the system. The multicast tree is constructed to place the nodes with greater altruism value at the higher layer of the tree. As compared with other studies in this area, ADALM exhibits innovative advantages in both altruism value computation and multicast tree construction. Firstly, the node's altruism value is generated from the feedback from its parent and children, which enables the system to detect the selfish nodes effectively. Peers don't need the extra probe messages to measure the QoS of their neighbors. During the process of tree

  8. Design of optical time-division multiplexed systems using the cascaded four-wave mixing in a highly nonlinear photonic crystal fiber for simultaneous time demultiplexing and wavelength multicasting

    Science.gov (United States)

    Hui, Zhan-Qiang; Zhang, Jian-Guo

    2015-07-01

    This paper reports a new design of optical time-division multiplexed (OTDM) systems that possess a functionality of simultaneous time demultiplexing and wavelength multicasting based on the cascaded four-wave mixing in a dispersion-flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF). A module of OTDM demultiplexing and wavelength multicasting can be feasibly implemented by using a 3 dB optical coupler, a high-power erbium-doped fiber amplifier, a short-length DF-HNL-PCF, and a wavelength demultiplexer in the simple configuration. We also carry out an experiment on the proposed system to demonstrate the 100-10 Gbit s-1 OTDM demultiplexing with wavelength conversion simultaneously at 4 multicast wavelengths. It is shown that error-free wavelength multicasting is achieved on two wavelength channels with the minimum power penalty of 3.2 dB relative to the 10 Gbit s-1 back-to-back measurement, whereas the bit error rates of other two multicasting channels are measured to be about 10-6-10-5. Moreover, we propose the use of a proper error-correcting code to improve the multicasting performance of such an OTDM system, and our work reveals that the resulting system can theoretically support error-free multicasting of the OTDM-demultiplexed signal on four wavelength channels.

  9. Optical, Electrical and Photocatalytic Properties of the Ternary Semiconductors ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS

    Directory of Open Access Journals (Sweden)

    Sandra Andrea Mayén-Hernández

    2014-01-01

    Full Text Available The effects of vacuum annealing at different temperatures on the optical, electrical and photocatalytic properties of polycrystalline and amorphous thin films of the ternary semiconductor alloys ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS were investigated in stacks of binary semiconductors obtained by chemical bath deposition. The electrical properties were measured at room temperature using a four-contact probe in the Van der Pauw configuration. The energy band gap of the films varied from 2.30 to 2.85 eV. The photocatalytic activity of the semiconductor thin films was evaluated by the degradation of an aqueous methylene blue solution. The thin film of ZnxCd1-xS annealed under vacuum at 300°C exhibited the highest photocatalytic activity.

  10. CD1A-positive cells and HSP60 (HSPD1) levels in keratoacanthoma and squamous cell carcinoma.

    Science.gov (United States)

    Cabibi, Daniela; Conway de Macario, Everly; Ingrao, Sabrina; Porcasi, Rossana; Zucco, Francesco; Macario, Alberto J L; Cappello, Francesco; Rappa, Francesca

    2016-01-01

    CD1a is involved in presentation to the immune system of lipid antigen derived from tumor cells with subsequent T cell activation. Hsp60 is a molecular chaperone implicated in carcinogenesis by, for instance, modulating the immune reaction against the tumor. We have previously postulated a synergism between CD1a and Hsp60 as a key factor in the activation of an effective antitumor immune response in squamous epithelia. Keratoacantomas (KAs) are benign tumors that however can transform into squamous cell carcinomas (SCCs), but the reasons for this malignization are unknown. In a previous study, we found that CD1a-positive cells are significantly more numerous in KA than in SCC. In this study, we analyzed a series of KAs and SCCs by immunohistochemistry for CD1a and Hsp60. Our results show that the levels of both are significantly lower in KA than in SCC and support the hypothesis that KA may evolve towards SCC if there is a failure of the local modulation of the antitumor immune response. The data also show that immunohistochemistry for CD1a and Hsp60 can be of help in differential diagnosis between KAs and well-differentiated forms of SCC.

  11. Alcatel-Lucent Service Routing Architect (SRA) self-study guide preparing for the BGP, VPRN and Multicast exams

    CERN Document Server

    Warnock, Glenn; Shaheen, Ghassan

    2015-01-01

    A comprehensive resource for professionals preparing for Alcatel-Lucent Service Routing Architect (SRA) certification Networking professionals are taking note of Alcatel-Lucent and its quick ascent in the networking and telecom industries. IP networking professionals looking for a comprehensive guide to obtaining the Alcatel-Lucent Service Routing Architect (SRA) certification will be pleased to learn of this new publication, Alcatel-Lucent Service Routing Architect (SRA) Self-Study Guide: Preparing for the BGP, VPRN and Multicast Exams. The book comprises approximately 2,600 pages of print a

  12. Optical, Electrical and Photocatalytic Properties of the Ternary Semiconductors ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS

    OpenAIRE

    Sandra Andrea Mayén-Hernández; David Santos-Cruz; Francisco de Moure-Flores; Sergio Alfonso Pérez-García; Liliana Licea-Jiménez; Ma. Concepción Arenas-Arrocena; José de Jesús Coronel-Hernández; José Santos-Cruz

    2014-01-01

    The effects of vacuum annealing at different temperatures on the optical, electrical and photocatalytic properties of polycrystalline and amorphous thin films of the ternary semiconductor alloys ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS were investigated in stacks of binary semiconductors obtained by chemical bath deposition. The electrical properties were measured at room temperature using a four-contact probe in the Van der Pauw configuration. The energy band gap of the films varied from 2.30 to 2...

  13. 基于CBT组播路由协议的组密钥管理协议分析与改进%Analyses and Improvement on Group Key Management Protocol Based on CBT Multicast Routing Protocol

    Institute of Scientific and Technical Information of China (English)

    张斌; 邬江兴

    2001-01-01

    In RFC1949,A. Ballardie proposed a method of scalable multicast key distribution based on the Core Based Tree multicast protocol fitting for wide-area IP multicasting. This paper analyses the method deeply,points out that the model can't resist the key compromise of a single member effectively,and proposes two kinds of improvement. One is the distributed generating and distributing group data encryption key,the other one is partitioning the group into subgroups. These improvements can increase the security and lifetime of the group key,and decrease the loss of compromise of a single group key encryption key.

  14. HIGH DENSITY CULTIVATION OF A RECOMBINANT CD-1 CELL LINE PRODUCING PROUROKINASE USING A BIOSILON MICROCARRIER CULTURE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    肖成祖; 黄子才; 张正光; 叶建新; 高丽华; 郭智霞; 程度胜; 周鹤山; 孔惟惟

    1994-01-01

    CD-1,a genetically-engineered CHO cell line,was cultivated with a Biosilon microcarrier culture system.We successfully cultivated CD-1 cells to a very high density(over 1 ×107 cells/ml).Prourokinase was stably secreted at about 180IU/106 cells/24h.Experiments showed that CD-1 cells growing on Biosilon microcarriers were able to spontaneously release from the microcarriers,then reattach and proliferate on fresh microcarries.This makes it very easy to scale up production.The microcarries could be reused several times without affecting adhesion ,proliferation and prourokinase secretion.With CM-PECC membrane radial flow chromatography and MPG chromatography,the prouroknase in conditioned medium could be purfied to a specific activity of 1×105IU/mg of protein.The purification factor was about 600 fold,and approxiamately 90% of the biological activity was recovered.

  15. Controllable synthesis of ZnxCd1-xS@ZnO core-shell nanorods with enhanced photocatalytic activity.

    Science.gov (United States)

    Xie, Shilei; Lu, Xihong; Zhai, Teng; Gan, Jiayong; Li, Wei; Xu, Ming; Yu, Minghao; Zhang, Yuan-Ming; Tong, Yexiang

    2012-07-17

    We report the synthesis of Zn(x)Cd(1-x)S@ZnO nanorod arrays via a facile two-step process and the implementation of these core-shell nanorods as an environmental friendly and recyclable photocatalyst for methyl orange degradation. The band gap of Zn(x)Cd(1-x)S@ZnO core-shell nanorods can be readily tunable by adjusting the ratio of Zn/Cd during the synthesis. These Zn(x)Cd(1-x)S@ZnO core-shell nanorods exhibit a high photocatalytic activity and good stability in the degradation of the methyl orange. Moreover, these films grown on FTO substrates make the collection and recycle of the photocatalyst easier. These findings may open new opportunities for the design of effective, stable, and easy-recyclable photocatalytic materials.

  16. Fabrication Of ZnxCd1 – xSe Nanowires by CVD Process and Photoluminescence Studies

    Directory of Open Access Journals (Sweden)

    R.P. Vijayalakshmi

    2011-01-01

    Full Text Available ZnxCd1 – xSe alloy nanowires with composition x = 0.2, 0.5 have been successfully synthesized by a simple thermal evaporation on the silicon substrate coated with a gold film of 20 Å thickness. The as-synthesized alloy nanowires, 70 - 150 nm in diameter and several tens of micrometer in length. The nanowires are single crystalline revealed from Transmission electron microscopy (TEM and XRD measurement. The structure of ZnxCd1 – xSe nanowires are hexagonal wurtzite with [01-10] growth direction. Energy gap of the ZnxCd1 – xSe nanowires are determined from micro photoluminescence measurements. The energy gap increases with increasing Zn concentration.

  17. Multiple tissue-specific isoforms of sulfatide activate CD1d-restricted type II NKT cells

    DEFF Research Database (Denmark)

    Blomqvist, Maria; Rhost, Sara; Teneberg, Susann

    2009-01-01

    of the long fatty acid (C24:0), resulted in reduced stimulatory capacity, and fatty acid hydroxylation abolished the response. Moreover, sulfatide was not responsible for the natural autoreactivity toward splenocytes by XV19 T hybridoma cells. Our results reveal a promiscuity in the recognition of sulfatide...... isoforms by a CD1d-restricted NKT-cell clone, and suggest that sulfatide, a major component of the myelin sheet and pancreatic beta-cells, is one of several natural ligands for type II CD1d-restricted NKT cells.......The glycosphingolipid sulfatide (SO(3)-3Galbeta1Cer) is a demonstrated ligand for a subset of CD1d-restricted NKT cells, which could regulate experimental autoimmune encephalomyelitis, a murine model for multiple sclerosis, as well as tumor immunity and experimental hepatitis. Native sulfatide...

  18. Improvement of the Response Time in an Open Source Audioconference Architecture Based on SIP Multicast Implemented with JainSIP, JainSDP and JGAP Libraries

    Directory of Open Access Journals (Sweden)

    Carlos M. Moreno

    2014-06-01

    Full Text Available Group services like the audioconference require a minimum level of quality of service for multicast sessions. This work proposes a new overlay multicast architecture based on SIP extensions and a genetic algorithm. The architecture consists of a SIP Extender client (SE, a Multicast Gateway Agent (MGA and a Multicast Manager (MM. The SE receives information about the most adequate MGA for it determined by a genetic algorithm inside the MM, then connects the chosen MGA and maintains connection with the MM itself. The genetic algorithm is implemented with JGAP(Java Genetic Algorithm Package libraries. The SE and MGA are programmed with JainSIP and JainSDP libraries which contain Java structures associated with the SIP protocol and session description. Some experiments over UTP wired and WiFi IEEE802.11n network were performed. Partial results with static and dynamic MGA selection show that, if we compare the joining and leaving time measured inside a station containing SE client programmed with JainSIP and JainSDP libraries versus SJphone proprietary client, the software engineering may have more influence than the medium access method in the response time for a potential group member. Even more, the genetic algorithm at the MM minimizes the response time at great scale.

  19. All-optical wavelength multicasting with extinction ratio enhancement using pump-modulated four-wave mixing in a dispersion-flattened nonlinear photonic crystal fiber

    DEFF Research Database (Denmark)

    Chow, K.K.; Shu, Chester; Lin, Chinlon;

    2006-01-01

    All optical wavelength multicasting at 4 x 10 Gb/s with extinction ratio enhancement has been demonstrated based on pump-modulated four-wave mixing in a nonlinear photonic crystal fiber. We show that the input signal wavelength can simultaneously convert to four different wavelengths, with a power...

  20. Dynamic Reconfiguration of IP Domain Middleware Stacks to Support Multicast Multimedia Distribution in a Heterogeneous Environment

    Directory of Open Access Journals (Sweden)

    Kevin Curran

    2005-01-01

    Full Text Available Seamless connectivity to multiple wireless networks independently of a fixed point is becoming increasingly important for mobile devices however wireless networks differ in bandwidth, size and access costs each requiring protocol functions to enable devices to communicate efficiently. In addition, due to the divergence of users and applications, traditional stacks are frequently enriched with additional functionality such as transport protocol functionality, synchronisation and presentation coding which can lead to a performance bottleneck due to the insufficient processing power and memory of portable devices. We argue that an extensible middleware is needed to cover small resource constrained devices to full-fledged desktop computers thus we investigate dynamic micro-protocols which enable devices to adopt specific protocol stacks at runtime in an attempt to optimise the stack to the functionality that is actually required by the application thus eliminating additional overhead functionality provided by generic stacks. A side effect of this is that it allows devices such as PDAs to offer protocol functions, which would not normally be available due to their memory constraints. Memory constrained devices are catered for through the deployment of a client-proxy overlay network where proxies offload processing. The problem of the ?common denominator bandwidth? is overcome through multicast media groups where clients subscribe to different quality of services in accordance with resource availability and move between groups according to bandwidth availability over time. Our end result is a Java middleware for multimedia streaming to heterogeneous mobile clients, utilising dynamic configuration of protocols with respect to application requirements and available network resources. Performance is increased through application specific tailored protocols and reducing protocol complexity allows stacks to fit inside the limited memory space of current

  1. Dietary phytoestrogens accelerate the time of vaginal opening in immature CD-1 mice.

    Science.gov (United States)

    Thigpen, Julius E; Haseman, Joseph K; Saunders, Hannah E; Setchell, Kenneth D R; Grant, Mary G; Forsythe, Diane B

    2003-12-01

    The purpose of the study reported here was to determine the effects of dietary phytoestrogens on the time of vaginal opening (VO) in immature CD-1 mice, and to correlate it with phytoestrogen and total metabolizable energy (ME) contents of the diet in an effort to determine the most appropriate diets(s) for comparing or evaluating the estrogenic or antiestrogenic activity of endocrine disruptor compounds (EDC). Mice were weaned at postnatal day (PND) 15 and fed the test diets from PND 15 to 30. Vaginal opening was recorded from PND 20 to 30. The phytoestrogen content of the diet was highly predictive (P phytoestrogen content. Time of VO in mice was significantly (P phytoestrogens, compared with those containing low phytoestrogen content. It was concluded that: dietary daidzein and genistein can significantly (P estrogenic activity of EDCs, and should be part of the standard protocol for evaluating EDCs. Phytoestrogen-free diet(s) containing the same amount of ME should be used in bioassays that compare the time of VO, or increases in uterine weight as end points for evaluating the estrogenic activity of an EDC.

  2. Olfactory sensitivity and odor structure-activity relationships for aliphatic carboxylic acids in CD-1 mice.

    Science.gov (United States)

    Can Güven, Selçuk; Laska, Matthias

    2012-01-01

    Using a conditioning paradigm, the olfactory sensitivity of CD-1 mice for a homologous series of aliphatic n-carboxylic acids (ethanoic acid to n-octanoic acid) and several of their isomeric forms was investigated. With all 14 odorants, the animals significantly discriminated concentrations as low as 0.03 ppm (parts per million) from the solvent, and with four odorants the best-scoring animals even detected concentrations as low as 3 ppt (parts per trillion). Analysis of odor structure-activity relationships showed that the correlation between olfactory detection thresholds of the mice for the unbranched carboxylic acids and carbon chain length can best be described as a U-shaped function with the lowest threshold values at n-butanoic acid. A significant positive correlation between olfactory detection thresholds and carbon chain length of the carboxylic acids with their branching next to the functional carboxyl group was found. In contrast, no such correlation was found for carboxylic acids with their branching at the distal end of the carbon chain relative to the functional carboxyl group. Finally, a significant correlation was found between olfactory detection thresholds and the position of the branching of the carboxylic acids. Across-species comparisons suggest that mice are more sensitive for short-chained (C(2) to C(4)) aliphatic n-carboxylic acids than other mammalian species, but not for longer-chained ones (C(5) to C(8)). Further comparisons suggest that odor structure-activity relationships are both substance class- and species-specific.

  3. Microelectronics Reliability

    Science.gov (United States)

    2017-01-17

    convey any rights or permission to manufacture, use, or sell any patented invention that may relate to them. This report was cleared for public release...testing for reliability prediction of devices exhibiting multiple failure mechanisms. Also presented was an integrated accelerating and measuring ...13  Table 2  T, V, F and matrix versus  measured  FIT

  4. Functional CD1d and/or NKT cell invariant chain transcript in horse, pig, African elephant and guinea pig, but not in ruminants.

    Science.gov (United States)

    Looringh van Beeck, Frank A; Reinink, Peter; Hermsen, Roel; Zajonc, Dirk M; Laven, Marielle J; Fun, Axel; Troskie, Milana; Schoemaker, Nico J; Morar, Darshana; Lenstra, Johannes A; Vervelde, Lonneke; Rutten, Victor P M G; van Eden, Willem; Van Rhijn, Ildiko

    2009-04-01

    CD1d-restricted invariant natural killer T cells (NKT cells) have been well characterized in humans and mice, but it is unknown whether they are present in other species. Here we describe the invariant TCR alpha chain and the full length CD1d transcript of pig and horse. Molecular modeling predicts that porcine (po) invariant TCR alpha chain/poCD1d/alpha-GalCer and equine (eq) invariant TCR alpha chain/eqCD1d/alpha-GalCer form complexes that are highly homologous to the human complex. Since a prerequisite for the presence of NKT cells is the expression of CD1d protein, we performed searches for CD1D genes and CD1d transcripts in multiple species. Previously, cattle and guinea pig have been suggested to lack CD1D genes. The CD1D genes of European taurine cattle (Bos taurus) are known to be pseudogenes because of disrupting mutations in the start codon and in the donor splice site of the first intron. Here we show that the same mutations are found in six other ruminants: African buffalo, sheep, bushbuck, bongo, N'Dama cattle, and roe deer. In contrast, intact CD1d transcripts were found in guinea pig, African elephant, horse, rabbit, and pig. Despite the discovery of a highly homologous NKT/CD1d system in pig and horse, our data suggest that functional CD1D and CD1d-restricted NKT cells are not universally present in mammals.

  5. Hydrothermal synthesis of monodisperse ZnxCd1-xS spheres and their photocatalytic properties%水热合成单分散球状ZnxCd1-xS及其光催化性质

    Institute of Scientific and Technical Information of China (English)

    贾志方; 王富民; 辛峰

    2011-01-01

    采用简单的水热合成路线制备高产量单分散球状ZnxCd1-xS,通过X射线衍射、扫描电镜以及紫外-可见漫反射对所得的产物进行表征.结果表明,所得产物呈现六方相纤锌矿结构,并且ZnxCd1-xS产物呈现出很好的均匀性与规则性.采用光催化降解罗丹明B反应来评价ZnxCd1-xS的光催化活性.其中,Zn0.4Cd0.6S具有最高的催化活性,并且在降解反应过程中表现出很高的稳定性.%Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis diffusion reflectance spectroscopy.The results indicate that all the prepared samples have the same hexagonal wurtzite phase and exhibit good size uniformity and regularity.Degradation of rhodamine-B (RhB) was used to evaluate the photocatalytic activities of ZnxCd1-xS samples.Zn0.4Cd0.6S possessed the best photocatalytic activity and exhibited high stability during the reaction.

  6. APPLICATION LAYER MULTICAST ALGORITHM BASED ON NODE HETEROGENEOUS%基于节点异构性的应用层组播算法

    Institute of Scientific and Technical Information of China (English)

    王君; 王以刚

    2011-01-01

    为降低组播树的维护开销、改善组播树的负载平衡、提高组播树的性能,给出一种基于节点异构性的应用层组播算法.与已有的应用层组播算法相比,综合考虑了节点的异构性(动态计算节点异构性,综合考虑节点的网络转发能力和计算能力来),提出了全新的组播树构建策略并通过黄牌节点的数量来及时调整组播树.仿真结果表明,该算法大大降低了端到端的延迟和平均链路伸展长度,提高了系统的稳定性.%To reduce the multicast tree maintenance cost, improve its load balance and performance, this paper proposes an application layer multicast algorithm based on node heterogeneous. Compared with existing application layer multicast algorithms, it comprehensively considers node heterogeneous ( dynamically calculates node heterogeneous, comprehensively considers the node's network forwarding capacity and computing power); then presents a new multicast tree construction strategy and timely adjust the multicast tree according to the number of yellow nodes. Simulation results show that the algorithm greatly shortens the delay between peers as well as the average link stretch length; therefore the system stability is improved.

  7. 无线网络终端协作多播技术研究%Cooperative Multicast Scheme Research in Wireless Networks

    Institute of Scientific and Technical Information of China (English)

    谢飞

    2014-01-01

    终端协作多播技术,因其能有效改善广播多播吞吐量的瓶颈问题而成为新的研究方向。针对当前多媒体广播多播业务的流行,对传统广播多播的缺点做了简要分析,介绍了协作通信与协作多播的基本原理,重点分析了当前国内外协作多播技术的研究现状,从中继节点的协作方式、协作策略与协作中继选择、多阶段协作多播三方面展开阐述,概括出当前的研究主要集中于提高吞吐量与降低系统功耗两方面。最后,对协作多播提出了展望,说明了协作多播走向商用还需解决的问题。%Multicast communication is an efficient mechanism for one-to-many transmissions over a broadcast wireless channel,but the group member with the worst channel condition becomes the bottleneck and results in conservative resource utilization. Cooperative multicast has gotten much attention because it can achieve high throughput than existing multicast scheme.A detailed introduction of the research status of cooperative multicast is given in this article,from which we find that most researches focus on the relay selection and the energy efficient cooperative multicast scheme.

  8. 分层迁移:分层多播拥塞控制中的快速响应方法%Layer Transfer: A Rapid Response Method in Layered Multicast Congestion Control

    Institute of Scientific and Technical Information of China (English)

    杨明; 张福炎

    2003-01-01

    There exists large Leave latency (often on the order of several seconds)in current Internet group management mechanism. This will cause layered multicast congestion control in slow response to network congestion. We give a new concept of layer transfer,which can implement rapid congestion response in layered multicast. Layer transfer will move congested layer data from one group to another ,and the receivers will determine whether to re-subscribe the moved layer or not according to their current situations. Layer transfer has a key feature that it replaces slow Leave process by fast Join process ,so it doesn't require any change to IGMP protocol ,routers ,or other multicast routing protocol. The simulation results show the new method can improve layered multicast sessions' fairness towards TCP sessions.

  9. Characterization of the Interaction of Staphylococcal Entertoxin B with CD1d Expressed in Human Renal Proximal Tubule Epithelial Cells

    Science.gov (United States)

    2015-02-04

    Software, Inc., San Diego , CA). RPTEC culture and fluorescence-based reporting RPTECs were grown in REBM culture medium supple- mented with a bullet kit...Med. 2007;232(9):1142 51. 32. Bendelac A, Rivera MN, Park SH, Roark JH. Mouse CD1 specific NK1 T cells: development, specificity, and function. Annu

  10. Computational structure activity relationship studies on the CD1d/glycolipid/TCR complex using AMBER and AUTODOCK.

    Science.gov (United States)

    Nadas, Janos; Li, Chenglong; Wang, Peng George

    2009-02-01

    The human CD1d protein presents a wide range of lipids to the TCR of invariant natural killer T cells (iNKT). Alpha-GalCer is one of the most potent iNKT stimulatory ligands presented by CD1d. The lipid portion of this ligand has been extensively investigated over the course of the past few years; however, the sugar portion of the ligand has received minimal attention. The following research focuses on computationally analyzing the recently crystallized CD1d/alpha-GalCer/TCR tertiary complex by molecular dynamics simulations using AMBER along with studying the structure activity relationship of the sugar headgroup also by simulation and docking using Autodock for a variety of alpha-GalCer analogs. The results show that the crystal structure is stable under simulation making it an accurate representation of the CD1d/alpha-GalCer/TCR complex and that modifications to the C2' and C3' positions of the sugar are not tolerated by the tertiary complex, whereas modifications to the C4' position are tolerated.

  11. Hiding Lipid Presentation: Viral Interference with CD1d-Restricted Invariant Natural Killer T (iNKT Cell Activation

    Directory of Open Access Journals (Sweden)

    Maaike E. Ressing

    2012-10-01

    Full Text Available The immune system plays a major role in protecting the host against viral infection. Rapid initial protection is conveyed by innate immune cells, while adaptive immunity (including T lymphocytes requires several days to develop, yet provides high specificity and long-lasting memory. Invariant natural killer T (iNKT cells are an unusual subset of T lymphocytes, expressing a semi-invariant T cell receptor together with markers of the innate NK cell lineage. Activated iNKT cells can exert direct cytolysis and can rapidly release a variety of immune-polarizing cytokines, thereby regulating the ensuing adaptive immune response. iNKT cells recognize lipids in the context of the antigen-presenting molecule CD1d. Intriguingly, CD1d-restricted iNKT cells appear to play a critical role in anti-viral defense: increased susceptibility to disseminated viral infections is observed both in patients with iNKT cell deficiency as well as in CD1d- and iNKT cell-deficient mice. Moreover, viruses have recently been found to use sophisticated strategies to withstand iNKT cell-mediated elimination. This review focuses on CD1d-restricted lipid presentation and the strategies viruses deploy to subvert this pathway.

  12. CD1b-mycolic acid tetramers demonstrate T-cell fine specificity for mycobacterial lipid tails.

    Science.gov (United States)

    Van Rhijn, Ildiko; Iwany, Sarah K; Fodran, Peter; Cheng, Tan-Yun; Gapin, Laurent; Minnaard, Adriaan J; Moody, D Branch

    2017-09-01

    Mycobacterium tuberculosis synthesizes a thick cell wall comprised of mycolic acids (MA), which are foreign antigens for human T cells. T-cell clones from multiple donors were used to determine the fine specificity of MA recognition by human αβ T cells. Most CD1-presented lipid antigens contain large hydrophilic head groups comprised of carbohydrates or peptides that dominate patterns of T-cell specificity. MA diverges from the consensus antigen motif in that it lacks a head group. Using multiple forms of natural and synthetic MA and MA-specific T-cells with different T-cell receptors, we found that, unlike antigens with larger head groups, lipid length strongly controlled T-cell responses to MA. In addition, the three forms of MA that naturally occur in M. tuberculosis that differ in modifications on the lipid tail, differ in their potency for activating MA-specific T-cell clones. Thus, naturally occurring MA forms should be considered as separate, partly cross-reactive antigens. Two of the three forms of MA could be loaded onto human CD1b proteins, creating working CD1b-MA tetramers. The creation of CD1b-MA tetramers represents a new tool for future studies that track the effector functions and kinetics of MA-specific T-cells ex vivo. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Distinct morphophenotypic features of chronic B-cell leukaemias identified with CD1c and CD23 antibodies.

    Science.gov (United States)

    Orazi, A; Cattoretti, G; Polli, N; Delia, D; Rilke, F

    1991-07-01

    Morphological criteria usually applied to diagnose various subtypes of B-cell chronic lymphoid leukaemia are largely subjective. Immunophenotyping of 61 relevant cases using a selected panel of monoclonal antibodies (mAb), showed that CD1c and CD23 mAb were able to separate B-cell chronic lymphocytic leukaemia (B-CLL) from other chronic B-cell lymphoproliferative diseases. Lymphocytes of B-CLL were CD1c-, CD23+, whereas those of other types of chronic B-cell leukaemia were CD1c+/-, CD23-, and CD38/-. Non-B-CLL cases had a significantly higher amount of large peroxidase-negative (unstained) cells analyzed with an automated blood cell counter (Technicon H6000). This type of volumetric assessment allowed a separation between typical and "atypical" B-CLL, which otherwise were both CD1c-, and CD23+. These combinations of phenotypic markers corresponded to well-defined haematopathologic entities, conventionally diagnosed on peripheral blood (PB) and bone marrow smears, and on histologic sections of lymph nodes and spleen.

  14. Procesamiento y presentación de antígenos lipídicos por moléculas CD1

    OpenAIRE

    ANABELL ALVARADO NAVARRO; MIGUEL ANGEL HERNÁNDEZ URZÚA

    2005-01-01

    Las moléculas CD1 se clasifican en dos grupos: el grupo 1 incluye las moléculas CD1a, CD1b, CD1c y el grupo 2 CD1d, las cuales interactúan con células T y NKT, respectivamente. A diferencia de las moléculas del MHC, presentan antígenos lipídicos y glucolipídicos de micobacterias. Las moléculas CD1 se localizan en compartimentos intracelulares de las APCs. Existe controversia sobre el procesamiento de los antígenos lipídicos, lo cual influye en la presentación y reconocimiento por células T a ...

  15. A Reliable Adaptive High-Definition Transmission System for Distance Learning

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    There is an increasing demand for supporting high-quality real-time audiovisual services for the next generation wired and wireless networks. However, due to variety of bandwidths of different networks, it is a great challenge for deployment. In this paper, a novel high-definition (HD) video transmission system was proposed which depends upon reliable compound multicast protocols and QoS control over the various kinds of networks.This system detects client's network condition and assigns it to a proper proxy. Each proxy is capable of detecting network parameters and adaptively tuning such transport parameters as bit rate, video resolution, frame rate and QoS mechanisms to this condition. It also provides FEC error recovery under consideration of characteristics of MPEG4 video codec. Our simulation demonstrates that different network clients such as ADSL, CERNET, and CERNET2 can receive more video reliability with less delay.

  16. INVESTIGATION ON THE HYPOGLYCEMIANT EFFECT OF SOME VEGETAL EXTRACTS IN EXPERIMENTAL INTOXICATIONS AT CD-1 MICE

    Directory of Open Access Journals (Sweden)

    Monica Bucă

    2016-12-01

    Full Text Available Using plants in treating some diseases has become a tradition, ‘the nature’s pharmacy’ being an important source of therapy. At present, the medicinal plants properties are being re-assessed due to progress made in chemical, pharmaceutical and clinical research of plants and due to forms obtained from vegetal products, but especially due to the advantages they offer. In the context of more frequent use of natural products with pharmaceutical and therapeutical aims, both at a national and at an international level, our research hints at highlighting and giving details about a series of effects produced by vegetal extracts of Aronia melanocarpa and Silybum marianum on certain physiological, biochemical and histopathological processes at CD1 mice. In this study, 2 hydro-alcoholic extracts obtained from 2 species of medicinal plants (Aronia melanocarpa and Silybum marianum, were tested in order to analyse the hypoglycemiant activity. The data accumulated in the specialty literature reveal that the phytotherapeutic use of extracts of Aronia melanocarpa and Silybum marianum is based only on the major pharmacologic effect while the intimate action mechanism of the two vegetal products, al cellular and subcellular level, is not known. Starting from these premises, we considered useful the initiation of a comparative study regarding the antidiabetic influence of fluid extracts of Aronia melanocarpa and Silybum marianum upon mice experimentally intoxicated with alloxan monohydrate solution. CDI mice were used as an experimental model in order to induce diabetes: alloxan monohydrate was injected intraperitoneal with concentration of 130 mg/kg body (Ahmed Saber Abu – zaiton, 2013, dissolved in physiological serum, during two weeks, at an interval of 3 days. Both extracts acted positively by lowering blood sugar and by returning to normal body weight in diabetic mice. Aronia extract has a pronounced effect compared to milk thistle extract for both

  17. Neurobehavioral development of CD-1 mice after combined gestational and postnatal exposure to ozone

    Energy Technology Data Exchange (ETDEWEB)

    Dell`Omo, G. [Section of Behavioral Pathophysiology, Lab. di Fisiopatologia di Organo e di Sistema, Istituto Superiore di Sanita, Rome (Italy); Fiore, M. [Section of Behavioral Pathophysiology, Lab. di Fisiopatologia di Organo e di Sistema, Istituto Superiore di Sanita, Rome (Italy); Petruzzi, S. [Section of Behavioral Pathophysiology, Lab. di Fisiopatologia di Organo e di Sistema, Istituto Superiore di Sanita, Rome (Italy); Alleva, E. [Section of Behavioral Pathophysiology, Lab. di Fisiopatologia di Organo e di Sistema, Istituto Superiore di Sanita, Rome (Italy); Bignami, G. [Section of Behavioral Pathophysiology, Lab. di Fisiopatologia di Organo e di Sistema, Istituto Superiore di Sanita, Rome (Italy)

    1995-09-01

    Outbred CD-1 mice were exposed continuously to ozone (O{sub 3}, 0.6 ppm) from 6 days prior to the formation of breeding pairs to the time of weaning of the offspring on postnatal day 22 (PND 22) or to PND 26. One half of the mice in each of eight O{sub 3} and eight control litters were subjected on PND 24 to a 20-min open-field test after IP treatment by either saline or scopolamine (2 mg/kg). The remaining mice (those exposed until PND 26) were subjected on PNDs 28-31 to a conditioned place preference (CPP) test, using a short schedule with a single IP injection on PND 29 of either d-amphetamine (3.3 mg/kg) or saline. Subsequently, the saline mice of the open-field experiment were used on PND 59 for an activity test in one of the CPP apparatus compartments after IP treatment by either d-amphetamine (same dose) or saline. In addition, the saline mice of the CPP experiment underwent a multitrial, step-through passive avoidance (PA) acquisition test on PND 59 or 60, followed 24 h later by a single-trial retention test. In the absence of effects on reproductive performance (proportion of successful pregnancies, litter size, offspring viability, and sex ratio), O{sub 3} offspring showed a long-lasting reduction in body weight without modification of sec differences. Ozone effects on neurobehavioral development were not large and quite selective, including: attenuation of the sex differences in several responses (rearing and sniffing in the open-field, activity in the final CPP test session); a change in response choices in the final CPP test, in the absence of a main effect on conditioning; a reduction of grooming in the activity test on PND 29; and impairment of PA acquisition limited to the initial period of training. (orig.)

  18. Bioluminescent imaging and histopathologic characterization of WEEV neuroinvasion in outbred CD-1 mice.

    Directory of Open Access Journals (Sweden)

    Aaron T Phillips

    Full Text Available Western equine encephalitis virus (WEEV; Alphavirus is a mosquito-borne virus that can cause severe encephalitis in humans and equids. Previous studies have shown that intranasal infection of outbred CD-1 mice with the WEEV McMillan (McM strain result in high mortality within 4 days of infection. Here in vivo and ex vivo bioluminescence (BLM imaging was applied on mice intranasally infected with a recombinant McM virus expressing firefly luciferase (FLUC to track viral neuroinvasion by FLUC detection and determine any correlation between BLM and viral titer. Immunological markers of disease (MCP-1 and IP-10 were measured and compared to wild type virus infection. Histopathology was guided by corresponding BLM images, and showed that neuroinvasion occurred primarily through cranial nerves, mainly in the olfactory tract. Olfactory bulb neurons were initially infected with subsequent spread of the infection into different regions of the brain. WEEV distribution was confirmed by immunohistochemistry as having marked neuronal infection but very few infected glial cells. Axons displayed infection patterns consistent with viral dissemination along the neuronal axis. The trigeminal nerve served as an additional route of neuroinvasion showing significant FLUC expression within the brainstem. The recombinant virus WEEV.McM.FLUC had attenuated replication kinetics and induced a weaker immunological response than WEEV.McM but produced comparable pathologies. Immunohistochemistry staining for FLUC and WEEV antigen showed that transgene expression was present in all areas of the CNS where virus was observed. BLM provides a quantifiable measure of alphaviral neural disease progression and a method for evaluating antiviral strategies.

  19. Olfactory Sensitivity for Six Predator Odorants in CD-1 Mice, Human Subjects, and Spider Monkeys

    Science.gov (United States)

    Sarrafchi, Amir; Odhammer, Anna M. E.; Hernandez Salazar, Laura Teresa; Laska, Matthias

    2013-01-01

    Using a conditioning paradigm, we assessed the olfactory sensitivity of six CD-1 mice (Mus musculus) for six sulfur-containing odorants known to be components of the odors of natural predators of the mouse. With all six odorants, the mice discriminated concentrations <0.1 ppm (parts per million) from the solvent, and with five of the six odorants the best-scoring animals were even able to detect concentrations <1 ppt (parts per trillion). Four female spider monkeys (Ateles geoffroyi) and twelve human subjects (Homo sapiens) tested in parallel were found to detect the same six odorants at concentrations <0.01 ppm, and with four of the six odorants the best-scoring animals and subjects even detected concentrations <10 ppt. With all three species, the threshold values obtained here are generally lower than (or in the lower range of) those reported for other chemical classes tested previously, suggesting that sulfur-containing odorants may play a special role in olfaction. Across-species comparisons showed that the mice were significantly more sensitive than the human subjects and the spider monkeys with four of the six predator odorants. However, the human subjects were significantly more sensitive than the mice with the remaining two odorants. Human subjects and spider monkeys significantly differed in their sensitivity with only two of the six odorants. These comparisons lend further support to the notion that the number of functional olfactory receptor genes or the relative or absolute size of the olfactory bulbs are poor predictors of a species’ olfactory sensitivity. Analysis of odor structure–activity relationships showed that in both mice and human subjects the type of alkyl rest attached to a thietane and the type of oxygen moiety attached to a thiol significantly affected olfactory sensitivity. PMID:24278296

  20. Maternal pravastatin prevents altered fetal brain development in a preeclamptic CD-1 mouse model.

    Directory of Open Access Journals (Sweden)

    Alissa R Carver

    Full Text Available Using an animal model, we have previously shown that preeclampsia results in long-term adverse neuromotor outcomes in the offspring, and this phenotype was prevented by antenatal treatment with pravastatin. This study aims to localize the altered neuromotor programming in this animal model and to evaluate the role of pravastatin in its prevention.For the preeclampsia model, pregnant CD-1 mice were randomly allocated to injection of adenovirus carrying sFlt-1 or its control virus carrying mFc into the tail vein. Thereafter they received pravastatin (sFlt-1-pra "experimental group" or water (sFlt-1 "positive control" until weaning. The mFc group ("negative control" received water. Offspring at 6 months of age were sacrificed, and whole brains underwent magnetic resonance imaging (MRI. MRIs were performed using an 11.7 Tesla vertical bore MRI scanner. T2 weighted images were acquired to evaluate the volumes of 28 regions of interest, including areas involved in adaptation and motor, spatial and sensory function. Cytochemistry and cell quantification was performed using neuron-specific Nissl stain. One-way ANOVA with multiple comparison testing was used for statistical analysis.Compared with control offspring, male sFlt-1 offspring have decreased volumes in the fimbria, periaquaductal gray, stria medullaris, and ventricles and increased volumes in the lateral globus pallidus and neocortex; however, female sFlt-1 offspring showed increased volumes in the ventricles, stria medullaris, and fasciculus retroflexus and decreased volumes in the inferior colliculus, thalamus, and lateral globus pallidus. Neuronal quantification via Nissl staining exhibited decreased cell counts in sFlt-1 offspring neocortex, more pronounced in males. Prenatal pravastatin treatment prevented these changes.Preeclampsia alters brain development in sex-specific patterns, and prenatal pravastatin therapy prevents altered neuroanatomic programming in this animal model.

  1. Blockade of invariant TCR-CD1d interaction specifically inhibits antibody production against blood group A carbohydrates

    Science.gov (United States)

    Tazawa, Hirofumi; Irei, Toshimitsu; Tanaka, Yuka; Igarashi, Yuka; Tashiro, Hirotaka

    2013-01-01

    Previously, we detected B cells expressing receptors for blood group A carbohydrates in the CD11b+CD5+ B-1a subpopulation in mice, similar to that in blood group O or B in humans. In the present study, we demonstrate that CD1d-restricted natural killer T (NKT) cells are required to produce anti-A antibodies (Abs), probably through collaboration with B-1a cells. After immunization of wild-type (WT) mice with human blood group A red blood cells (A-RBCs), interleukin (IL)-5 exclusively and transiently increased and the anti-A Abs were elevated in sera. However, these reactions were not observed in CD1d−/− mice, which lack NKT cells. Administration of anti-mouse CD1d blocking monoclonal Abs (mAb) prior to immunization abolished IL-5 production by NKT cells and anti-A Ab production in WT mice. Administration of anti-IL-5 neutralizing mAb also diminished anti-A Ab production in WT mice, suggesting that IL-5 secreted from NKT cells critically regulates anti-A Ab production by B-1a cells. In nonobese diabetic/severe combined immunodeficient (NOD/SCID/γcnull) mice, into which peripheral blood mononuclear cells from type O human volunteers were engrafted, administration of anti-human CD1d mAb prior to A-RBC immunization completely inhibited anti-A Ab production. Thus, anti-CD1d treatment might constitute a novel approach that could help in evading Ab-mediated rejection in ABO-incompatible transplant recipients. PMID:23943651

  2. Tuning Equilibrium Compositions in Colloidal Cd1-xMnxSe Nanocrystals Using Diffusion Doping and Cation Exchange.

    Science.gov (United States)

    Barrows, Charles J; Chakraborty, Pradip; Kornowske, Lindsey M; Gamelin, Daniel R

    2016-01-26

    The physical properties of semiconductor nanocrystals can be tuned dramatically via composition control. Here, we report a detailed investigation of the synthesis of high-quality colloidal Cd1-xMnxSe nanocrystals by diffusion doping of preformed CdSe nanocrystals. Until recently, Cd1-xMnxSe nanocrystals proved elusive because of kinetic incompatibilities between Mn(2+) and Cd(2+) chemistries. Diffusion doping allows Cd1-xMnxSe nanocrystals to be prepared under thermodynamic rather than kinetic control, allowing access to broader composition ranges. We now investigate this chemistry as a model system for understanding the characteristics of nanocrystal diffusion doping more deeply. From the present work, a Se(2-)-limited reaction regime is identified, in which Mn(2+) diffusion into CdSe nanocrystals is gated by added Se(2-), and equilibrium compositions are proportional to the amount of added Se(2-). At large added Se(2-) concentrations, a solubility-limited regime is also identified, in which x = xmax = ∼0.31, independent of the amount of added Se(2-). We further demonstrate that Mn(2+) in-diffusion can be reversed by cation exchange with Cd(2+) under exactly the same reaction conditions, purifying Cd1-xMnxSe nanocrystals back to CdSe nanocrystals with fine tunability. These chemistries offer exceptional composition control in Cd1-xMnxSe NCs, providing opportunities for fundamental studies of impurity diffusion in nanocrystals and for development of compositionally tuned nanocrystals with diverse applications ranging from solar energy conversion to spin-based photonics.

  3. Establishment and characterization of CD-1 neonatal female germline stem cell lines%新生CD-1小鼠雌性生殖干细胞的建系及生物学特征

    Institute of Scientific and Technical Information of China (English)

    毕海委; 吴际

    2014-01-01

    BACKGROUND:In traditional view, the germ cels in mammal ovaries were considered to lose the capacity of self-renew after birth. However, recent studies have showed the existence of female germline stem cels (FGSCs) which take the responsibility for regenerating oocytes in the ovaries of postnatal mammals. OBJECTIVE:To establish the FGSC line and to explore the biological characterization of the FGSC line from neonatal CD-1 mouse ovaries. METHODS:Using two-step enzymatic digestion and immunomagnetic purification, Fragilis-positive cels were isolated from neonatal CD-1 mice ovaries and subjected to long-term culture. Then their biological characteristics were studies with RT-PCR, fluorescent immunocytochemistry and cytogenetic analysis. RESULTS AND CONCLUSION:FGSCs from neonatal CD-1 mice aged 3-5 days were isolated and long-term cultured for 70 passages to establish a cellline. This cellline expressed Mvh, Dazl, Oct-4, Stela, Blimp1, Fragilis, and was proven to be mitoticaly active germ cels by BrdU/Fragilis dual immunofluorescence analysis. Moreover, cytogenetic analysis by Gimsa staining confirmed their normal karyotype. In al, these results indicate the existence of FGSCs with mitotic activity in neonatal CD-1 mouse ovaries.%背景:传统观点认为雌性哺乳动物出生后不再产生新的卵母细胞,近年来多项研究表明出生后哺乳动物卵巢中存在能再生卵子的雌性生殖干细胞。  目的:从新生CD-1小鼠卵巢中分离、纯化雌性生殖干细胞并建系及进行生物学特征研究。  方法:通过两步酶消化法和免疫磁珠分选从新生 CD-1小鼠卵巢中分离与纯化雌性生殖干细胞并体外长期培养,然后通过RT-PCR、细胞免疫荧光化学和核型分析鉴定其生物学特征。  结果与结论:从3-5 d龄CD-1小鼠卵巢中分离出雌性生殖干细胞并建立细胞系,目前已在体外长期培养15个月,共传代70多次。该细胞系表达Mvh,Dazl,Oct-4

  4. Spin-polarized structural, electronic, and magnetic properties of diluted magnetic semiconductors Cd(1-x)Mn(x)S and Cd(1-x)Mn(x)Se in zinc blende phase.

    Science.gov (United States)

    Nazir, S; Ikram, N; Tanveer, M; Shaukat, A; Saeed, Y; Reshak, Ali Hussain

    2009-05-21

    We studied the structural, spin-polarized electronic band structures, density of states, and magnetic properties of the diluted magnetic semiconductors (DMSs) Cd(1-x)Mn(x)S and Cd(1-x)Mn(x)Se in zinc blende phase (B3) with 25% Mn by using the ab initio method. The calculations were performed by using the full potential linearized augmented plane wave plus local orbitals (FP-L/APW+lo) method within the spin-polarized density functional theory and the local spin density approximation (LSDA). Calculated electronic band structures and the density of states of these DMSs are discussed in terms of the contribution of Mn 3d(5)4s(2), Cd 4d(10)5s(2), S 3s(2)3p(4), and Se 4s(2)4p(4) partial density of states and we also compute the local magnetic moments. We estimated the spin-exchange splitting energies, Delta(x)(d) and Delta(x)(p-d), produced by the Mn 3d states, and we found that the effective potential for the minority spin is more attractive than that for the majority spin. We determine the s-d exchange constant N(0)alpha and p-d exchange constant N(0)beta, which resembles a typical magneto-optical experiment. The calculated total magnetic moment is found to be 5.0020 and 5.00013 mu(B) for Cd(1-x)Mn(x)S and Cd(1-x)Mn(x)Se, respectively. These values indicate that every Mn impurity adds no hole carriers to the perfect CdS and CdSe crystals. Moreover, we found that p-d hybridization reduces the local magnetic moment of Mn from its free space charge value of 5.0micro(B) and produces small local magnetic moments on the nonmagnetic Cd and S sites.

  5. Preparation,Properties and Photovoltaic Implication of Polycrystalline Cd1-xZnxTe Thin Films%Cd1-xZnxTe多晶薄膜的制备、性能与光伏应用

    Institute of Scientific and Technical Information of China (English)

    邵烨; 郑家贵; 蔡道林; 张静全; 蔡伟; 武莉莉; 蔡亚平; 李卫; 冯良桓

    2003-01-01

    用共蒸发法制备了Cd1-xZnxTe多晶薄膜,薄膜结构属立方晶系空间群F43m.通过透射光谱的测量,计算光能隙,得到室温时薄膜的光能隙随组分x值的变化满足二次方关系.作为对异质结界面的修饰,提出了有Cd1-x-ZnxTe过渡层的CdS/CdTe/Cd1-xZnxTe/ZnTe∶Cu电池.并在相同工艺下制备了CdS/CdTe/Cd0.4Zn0.6Te/ZnTe∶Cu与CdS/CdTe/ZnTe∶Cu太阳电池,发现前者比后者效率平均增加了35.0%.

  6. Grid reliability

    CERN Document Server

    Saiz, P; Rocha, R; Andreeva, J

    2007-01-01

    We are offering a system to track the efficiency of different components of the GRID. We can study the performance of both the WMS and the data transfers At the moment, we have set different parts of the system for ALICE, ATLAS, CMS and LHCb. None of the components that we have developed are VO specific, therefore it would be very easy to deploy them for any other VO. Our main goal is basically to improve the reliability of the GRID. The main idea is to discover as soon as possible the different problems that have happened, and inform the responsible. Since we study the jobs and transfers issued by real users, we see the same problems that users see. As a matter of fact, we see even more problems than the end user does, since we are also interested in following up the errors that GRID components can overcome by themselves (like for instance, in case of a job failure, resubmitting the job to a different site). This kind of information is very useful to site and VO administrators. They can find out the efficien...

  7. Temperature dependence of the fundamental band gap parameters in cadmium-rich ZnCd1-Se using photoluminescence spectroscopy

    Indian Academy of Sciences (India)

    Lalita Gupta; S Rath; S C Abbi; F C Jain

    2003-10-01

    Thin films of ternary ZnCd1-Se were deposited on GaAs (100) substrate using metal-organic-chemical-vapour-deposition (MOCVD) technique. Temperature dependence of the near-band-edge emission from these Cd-rich Zn Cd1-Se (for = 0.025, 0.045) films has been studied using photoluminescence spectroscopy. Relevant parameters that describe temperature variation of the energy and broadening of the fundamental band gap have been evaluated using various models including the two-oscillator model, the Bose–Einstein model and the Varshni model. While all these models suffice to explain spectra at higher temperatures, the two-oscillator model not only explains low temperature spectra adequately but also provides additional information concerning phonon dispersion in these materials.

  8. Laser ablation and photostimulated passivation of the surface of Cd1–хZnхTe crystals

    Directory of Open Access Journals (Sweden)

    Zagoruiko Yu. A.

    2011-06-01

    Full Text Available A new physical method of Cd1–хZnхTe-detectors passivation is proposed — the treatment of crystal surface by a laser ablation (LA with subsequent photostimulated passivation (PhSP, during wich a high-resistance oxide layer is formed on it’s surface after the surface cleaning under intensive light irradiation effect. It is shown that the method of LA+PhSP is manufacturable and in comparison with PhSP and PhESP methods developed earlier provides a thick, homogeneous and high-oxide films, which significantly increases the surface resistivity of Cd1–хZnхTe samples and reduces leakage currents in them.

  9. Proposal and Performance Evaluation of a Multicast Routing Protocol for Wireless Mesh Networks Based on Network Load

    Directory of Open Access Journals (Sweden)

    Kiyotaka Oe

    2015-01-01

    Full Text Available Wireless Mesh Networks (WMNs can provide wide range Wireless Local Area Networks (WLANs area by connecting Access Points (APs of WLANs with each other using radio communications. A routing protocol is very important to keep communication quality over radio multihop communications because radio waves are impacted much by surrounding environment. When we use multiuser shared applications like a video conference and an IP phone, it is predicted that large amount of traffic flows on network. Therefore, we should consider network loads to use these applications. In this paper, we propose a multicast routing protocol for WMNs which considers network loads and hop count. Furthermore, we evaluate performance by simulation. In the simulation results, we show that the proposed protocol has better performance than a conventional protocol (MAODV at high loaded scenario.

  10. Impact of Sybil and Wormhole Attacks in Location Based Geographic Multicast Routing Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Shyamala Ramachandran

    2011-01-01

    Full Text Available Problem statement: Wireless sensor networks have been used in many applications, such as home automation, military surveillances and entity tracking systems. The sensor nodes have low computational capabilities and are highly resource constrained. Routing protocols of wireless sensor networks are prone to various routing attacks, such as black hole, rushing, wormhole, Sybil and denial of service attacks. Approach: The objective of this study was to examine the effects of wormhole in conjunction with Sybil attack on a location based-Geographic Multicast Routing (GMR protocol. Results: The NS-2 based simulation was used in analyzing the wormhole in conjunction with Sybil attack on GMR. Conclusion: It is found that, the Sybil attack degrades the network performance by 24% and the wormhole attack by 20%.

  11. Inhibition of Neuroblastoma Tumor Growth by Ketogenic Diet and/or Calorie Restriction in a CD1-Nu Mouse Model

    OpenAIRE

    2015-01-01

    Introduction Neuroblastoma is a malignant pediatric cancer derived from neural crest cells. It is characterized by a generalized reduction of mitochondrial oxidative phosphorylation. The goal of the present study was to investigate the effects of calorie restriction and ketogenic diet on neuroblastoma tumor growth and monitor potential adaptive mechanisms of the cancer’s oxidative phosphorylation system. Methods Xenografts were established in CD-1 nude mice by subcutaneous injection of two ne...

  12. CD1d-dependent NKT cells play a protective role in acute and chronic arthritis models by ameliorating antigen-specific Th1 responses

    DEFF Research Database (Denmark)

    Teige, Anna; Bockermann, Robert; Hasan, Maruf

    2010-01-01

    A protective and anti-inflammatory role for CD1d-dependent NKT cells (NKTs) has been reported in experimental and human autoimmune diseases. However, their role in arthritis has been unclear, with conflicting reports of CD1d-dependent NKTs acting both as regulatory and disease-promoting cells...

  13. Coexpression of CD1a, langerin and Birbeck's granules in Langerhans cell histiocytoses (LCH in children: ultrastructural and immunocytochemical studies.

    Directory of Open Access Journals (Sweden)

    Marzena Podhorska-Okołów

    2007-03-01

    Full Text Available Langerhans cell histiocytoses (LCH represent rare diseases of unclear etiology and pathogenesis. Most of the cases include children, 1 to 15 years of age, and various organs are involved (bones, skin, liver, lymph nodes, bone marrow and other. The diagnosis of LCH used to be established by biopsy of the inflamed tissue and demonstration of expression of markers specific for Langerhans cells: CD1a and langerin. The diagnosis can be ultimately confirmed by demonstration of Birbeck's granules in the electron microscopy. The present study was aimed at immunocytochemical demonstration, in the examined LCH material (skin, bones, lymph nodes, of the specific antigen expression and at comparing it with the presence of Birbeck's granules. In the examined 11 cases co-expression of CD1a with langerin and with the presence of Birbeck's granules was noted. Also in all examined biopsies the expression of S-100 protein on inflammatory cells was found. The results corroborate the usefulness of immunocytochemical studies on CD 1 a and langerin expression in diagnosis of LCH.

  14. The Effects of Perioperative Analgesia on Litter Size in Crl:CD1(ICR) Mice Undergoing Embryo Transfer

    Science.gov (United States)

    Goulding, David R; Myers, Page H; Goulding, Eugenia H; Blankenship, Terry L; Grant, Mary F; Forsythe, Diane B

    2010-01-01

    The objective of this study was to evaluate the effect on litter size of 2 analgesics used perioperatively during mouse embryo transfer surgery. Day 2.5 pseudopregnant CD1 mice (n = 96) were divided equally into 2 analgesic treatment groups and a saline control group. Each mouse received a single, subcutaneous dose of buprenorphine hydrochloride (0.1 mg/kg), flunixin meglumine (2.5 mg/kg), or saline immediately after induction of anesthesia with 2.5% isoflurane. Each mouse then was prepared for aseptic surgery. Blastocysts had previously been collected from C57BL/6NCrl female mice that were synchronized and superovulated by using pregnant mare serum gonadotropin and human chorionic gonadotropin and mated with C57BL/6NTac male mice 3.5 d before collection. Viable blastocysts were pooled, and 8 were selected arbitrarily and transplanted into the right uterine horn of each pseudopregnant CD1 mouse. Mice were monitored throughout pregnancy, and the number of pups at birth was documented. No statistically significant difference was found between the 3 groups. These results indicate that perioperative analgesic treatment with buprenorphine or flunixin in the CD1 mouse undergoing embryo transfer is not associated with increased embryonic loss. PMID:20819387

  15. Hollow ZnxCd1−xS nanospheres with enhanced photocatalytic activity under visible light

    Science.gov (United States)

    Jin, Ying; Zhang, Haoyun; Song, Chuang; Wang, Lanfang; Lu, Qingyi; Gao, Feng

    2016-01-01

    Formation of solid solutions is a good strategy to acquire materials with special properties and bring forth new type of applications or enhance the performance of currently existing devices. In this study, hollow ZnxCd1−xS nanospheres with different molar ratios were synthesized via a facile hydrothermal process. The products were fully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and UV-vis absorption spectroscopy. It was found that the photocatalysis performance of the as-prepared samples could be enhanced by formation of ZnxCd1−xS solid solutions. In addition, their photocatalytic activities are dependent on the Zn/Cd molar ratios and nanostructures of ZnxCd1−xS solid solutions. Hollow Zn0.2Cd0.8S spheres exhibit extremely high photocatalytic activity and good re-usability, and the photocatalytic conversion of RhB reaches as high as 96% after 50 min of irradiation. PMID:27444737

  16. Hollow ZnxCd1‑xS nanospheres with enhanced photocatalytic activity under visible light

    Science.gov (United States)

    Jin, Ying; Zhang, Haoyun; Song, Chuang; Wang, Lanfang; Lu, Qingyi; Gao, Feng

    2016-07-01

    Formation of solid solutions is a good strategy to acquire materials with special properties and bring forth new type of applications or enhance the performance of currently existing devices. In this study, hollow ZnxCd1‑xS nanospheres with different molar ratios were synthesized via a facile hydrothermal process. The products were fully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and UV-vis absorption spectroscopy. It was found that the photocatalysis performance of the as-prepared samples could be enhanced by formation of ZnxCd1‑xS solid solutions. In addition, their photocatalytic activities are dependent on the Zn/Cd molar ratios and nanostructures of ZnxCd1‑xS solid solutions. Hollow Zn0.2Cd0.8S spheres exhibit extremely high photocatalytic activity and good re-usability, and the photocatalytic conversion of RhB reaches as high as 96% after 50 min of irradiation.

  17. CM Multicast Technology Research and Test Plan%CM 组播技术研究及测试方案

    Institute of Scientific and Technical Information of China (English)

    谈君

    2014-01-01

    以Broadcom公司生产的Cable Modem专用芯片BCM3383为基础,以eCos为开发平台,开发了基于DOCSIS 3.0的高性能Cable Modem产品,此产品主要拥有Residential Gateway、WiFi、MTA等功能模块,主要研究Cable Modem在HFC网络中对组播功能的支持,并且提出组播测试方案。%Based on the chip of BCM3383 produced by Broadcom , develop DOCSIS 3.0 cable modem produc-tion with high performance based on e-Cos system .This production has Residential Gateway ,WiFi,MTA mod-ule .In the thesis , research the support of multicast feature in HFC network , and propose the test plan of multi-cast.

  18. 多源交互式应用层组播路由协议%Multi-Source Interactive Application Layer Multicast Routing Protocol

    Institute of Scientific and Technical Information of China (English)

    高建敏; 陆慧梅; 曹元大

    2011-01-01

    Application layer multicast (ALM) without expanding the basic underlying network can support greater range of multicast communications, which makes it a popular mechanism for multicast applications.However, compared with the traditional IP multicast, ALM has larger network delay and the node stability is poor, which makes it become a unique and challenging problem to implement multi-source interactive multicast application.In this paper, an ALM protocol called Thunder is proposed.According to the roles of members in the group, Thunder divides the interactive group into core-network and peripheral-tree.The core-network consists of the multicast data sources.By using Mesh-Tree structure, it constructs an optimal distribution tree for each data source and pursues fast forwarding to optimize the interactive process.The peripherals-tree is a tree structure composed by the unstable members which just receive data or only produce a small amount of data.Additionally,Peripherals-tree structure allows more members to receive multicast data.Those unstable nodes will not influence the interaction process of core-network, so the response speed and the protocol scalability of the interactive process are improved.Experiments demonstrate that Thunder can decrease network delay of interactive ALM and improve the scalability, which makes the multi-source interactive multicast applications be deployed and implemented more easily.%应用层组播无需扩充底层基础网络就可以实现较大范围的组播通信,已成为倍受瞩目的组播实现机制.但相对于传统的IP组播,应用层组播的网络延迟大,节点稳定性差,使得采用应用层组播来实现多源交互式组播应用成为一个独特的具有挑战性的问题.Thunder协议将组播结构分为核心网和外围树两部分:核心网通过Mesh-Tree结构追求快速转发以优化交互式过程;外围树允许更多的成员接收组播数据,却不会对交互过程产生影响,可提高协议

  19. 量子隐形传态网络的广播与组播%Broadcast and multicast in quantum teleportation internet

    Institute of Scientific and Technical Information of China (English)

    周小清; 邬云文

    2012-01-01

    The physical principle of broadcast and multicast is given. When Alice needs to send out an information, she sends out a conjunction claim signal to the switch that connects with hers. After receiving the conjunction claim the signal, the switch pass to examines the purpose address to judge whether it is a point-to-point communication or broadcast and multicast. If the purpose address is A or B or C address, then the switch carries on the correspondence operation of point-to-point; if the purpose address is a D address or an address (local or appointed network webcasting) with special meaning, then the switch carries on the correspondence operation of broadcast and multicast. With broadcast and multicast, the fidelity decreases with the increase of receiving terminal number, and its limit is 2/3.%给出了广播与组播的物理原理.当Alice需要发送信息时,就向与自己相连的交换机发送一连接请求信号,交换机收到连接请求信号后通过检测目的地址判断是点到点的通信还是组播与广播;若目的地址是A类、B类或C类地址,则进行点到点的通信操作;若目的地址是D类地址或是有特殊意义的地址(本地网络,指定网络广播),则启动量子信息的广播与组播操作.广播与组播时的保真度随受话终端数的增加而减小,其极限为2/3.

  20. Flexible and scalable wavelength multicast of coherent optical OFDM with tolerance against pump phase-noise using reconfigurable coherent multi-carrier pumping.

    Science.gov (United States)

    Lu, Guo-Wei; Bo, Tianwai; Sakamoto, Takahide; Yamamoto, Naokatsu; Chan, Calvin Chun-Kit

    2016-10-03

    Recently the ever-growing demand for dynamic and high-capacity services in optical networks has resulted in new challenges that require improved network agility and flexibility in order for network resources to become more "consumable" and dynamic, or elastic, in response to requests from higher network layers. Flexible and scalable wavelength conversion or multicast is one of the most important technologies needed for developing agility in the physical layer. This paper will investigate how, using a reconfigurable coherent multi-carrier as a pump, the multicast scalability and the flexibility in wavelength allocation of the converted signals can be effectively improved. Moreover, the coherence in the multiple carriers prevents the phase noise transformation from the local pump to the converted signals, which is imperative for the phase-noise-sensitive multi-level single- or multi-carrier modulated signal. To verify the feasibility of the proposed scheme, we experimentally demonstrate the wavelength multicast of coherent optical orthogonal frequency division multiplexing (CO-OFDM) signals using a reconfigurable coherent multi-carrier pump, showing flexibility in wavelength allocation, scalability in multicast, and tolerance against pump phase noise. Less than 0.5 dB and 1.8 dB power penalties at a bit-error rate (BER) of 10-3 are obtained for the converted CO-OFDM-quadrature phase-shift keying (QPSK) and CO-OFDM-16-ary quadrature amplitude modulation (16QAM) signals, respectively, even when using a distributed feedback laser (DFB) as a pump source. In contrast, with a free-running pumping scheme, the phase noise from DFB pumps severely deteriorates the CO-OFDM signals, resulting in a visible error-floor at a BER of 10-2 in the converted CO-OFDM-16QAM signals.