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Sample records for multicast congestion control

  1. Reliable on-demand multicast routing with congestion control in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Tang, Ken; Gerla, Mario

    2001-07-01

    In this paper, we address the congestion control multicast routing problem in wireless ad hoc networks through the medium access control (MAC) layer. We first introduce the Broadcast Medium Window (BMW) MAC protocol, which provides reliable delivery to broadcast packets at the MAC layer. We then extend the wireless On-Demand Multicast Routing Protocol (ODMRP) to facilitate congestion control in ad hoc networks using BMW. Through simulation, we show that ODMRP with congestion control adapts well to multicast sources that are aggressive in data transmissions.

  2. Evaluating the Multicast Control Protocol on a Multicasting Network Architecture

    NASA Astrophysics Data System (ADS)

    Stergiou, E.; Meletiou, G.; Vasiliadis, D. C.; Rizos, G. E.; Margariti, S. V.

    2007-12-01

    In this paper a reliable multicasting architecture presented. This architecture operates using a Multicasting Firewall over the Multicast Control Protocol (MCP). Our aim was to evaluate the transition times of specific packets such as the IGMPv2 reports in the proposed multicasting network. In our study, multicasting experiments presented and analyzed. The obtained results of our experiments clearly show that the average validation times of IGMP reports on the Multicast Control Server smoothly increase versus the number of clients.

  3. Reliable multicast protocol specifications flow control and NACK policy

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    This appendix presents the flow and congestion control schemes recommended for RMP and a NACK policy based on the whiteboard tool. Because RMP uses a primarily NACK based error detection scheme, there is no direct feedback path through which receivers can signal losses through low buffer space or congestion. Reliable multicast protocols also suffer from the fact that throughput for a multicast group must be divided among the members of the group. This division is usually very dynamic in nature and therefore does not lend itself well to a priori determination. These facts have led the flow and congestion control schemes of RMP to be made completely orthogonal to the protocol specification. This allows several differing schemes to be used in different environments to produce the best results. As a default, a modified sliding window scheme based on previous algorithms are suggested and described below.

  4. A Loss Tolerant Rate Controller for Reliable Multicast

    NASA Technical Reports Server (NTRS)

    Montgomery, Todd

    1997-01-01

    This paper describes the design, specification, and performance of a Loss Tolerant Rate Controller (LTRC) for use in controlling reliable multicast senders. The purpose of this rate controller is not to adapt to congestion (or loss) on a per loss report basis (such as per received negative acknowledgment), but instead to use loss report information and perceived state to decide more prudent courses of action for both the short and long term. The goal of this controller is to be responsive to congestion, but not overly reactive to spurious independent loss. Performance of the controller is verified through simulation results.

  5. Adaptive power-controllable orbital angular momentum (OAM) multicasting

    PubMed Central

    Li, Shuhui; Wang, Jian

    2015-01-01

    We report feedback-assisted adaptive multicasting from a single Gaussian mode to multiple orbital angular momentum (OAM) modes using a single phase-only spatial light modulator loaded with a complex phase pattern. By designing and optimizing the complex phase pattern through the adaptive correction of feedback coefficients, the power of each multicast OAM channel can be arbitrarily controlled. We experimentally demonstrate power-controllable multicasting from a single Gaussian mode to two and six OAM modes with different target power distributions. Equalized power multicasting, “up-down” power multicasting and “ladder” power multicasting are realized in the experiment. The difference between measured power distributions and target power distributions is assessed to be less than 1 dB. Moreover, we demonstrate data-carrying OAM multicasting by employing orthogonal frequency-division multiplexing 64-ary quadrature amplitude modulation (OFDM 64-QAM) signal. The measured bit-error rate curves and observed optical signal-to-noise ratio penalties show favorable operation performance of the proposed adaptive power-controllable OAM multicasting. PMID:25989251

  6. Design of controllable multicast for IPTV over EPON

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

    The character of 1Gbps bandwidth and tree-based structure make EPON very suitable for broadcast or multicast services such as IPTV. In this paper we focus on security mechanisms that should be available to groups that specifically request it, and therefore are willing to pay the extra cost of implementing those mechanisms. We concentrate on two issues: how unauthorized multicast traffic can be prevented by means of multicast transit traffic control; how a group's susceptibility is likely to be reduced by means of multicast group access control. We have proposed a novel scheme that should be available to multicast groups that desire precautionary measures be taken to avert the threats of Invalid source and unauthorized access.

  7. Using IGMP V3 for controllable multicast over EPON

    NASA Astrophysics Data System (ADS)

    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.

  8. Authenticated IGMP for Controlling Access to Multicast Distribution Tree

    NASA Astrophysics Data System (ADS)

    Park, Chang-Seop; Kang, Hyun-Sun

    A receiver access control scheme is proposed to protect the multicast distribution tree from DoS attack induced by unauthorized use of IGMP, by extending the security-related functionality of IGMP. Based on a specific network and business model adopted for commercial deployment of IP multicast applications, a key management scheme is also presented for bootstrapping the proposed access control as well as accounting and billing for CP (Content Provider), NSP (Network Service Provider), and group members.

  9. A Stateful Multicast Access Control Mechanism for Future Metro-Area-Networks.

    ERIC Educational Resources Information Center

    Sun, Wei-qiang; Li, Jin-sheng; Hong, Pei-lin

    2003-01-01

    Multicasting is a necessity for a broadband metro-area-network; however security problems exist with current multicast protocols. A stateful multicast access control mechanism, based on MAPE, is proposed. The architecture of MAPE is discussed, as well as the states maintained and messages exchanged. The scheme is flexible and scalable. (Author/AEF)

  10. Congestion control and routing over satellite networks

    NASA Astrophysics Data System (ADS)

    Cao, Jinhua

    Satellite networks and transmissions find their application in fields of computer communications, telephone communications, television broadcasting, transportation, space situational awareness systems and so on. This thesis mainly focuses on two networking issues affecting satellite networking: network congestion control and network routing optimization. Congestion, which leads to long queueing delays, packet losses or both, is a networking problem that has drawn the attention of many researchers. The goal of congestion control mechanisms is to ensure high bandwidth utilization while avoiding network congestion by regulating the rate at which traffic sources inject packets into a network. In this thesis, we propose a stable congestion controller using data-driven, safe switching control theory to improve the dynamic performance of satellite Transmission Control Protocol/Active Queue Management (TCP/AQM) networks. First, the stable region of the Proportional-Integral (PI) parameters for a nominal model is explored. Then, a PI controller, whose parameters are adaptively tuned by switching among members of a given candidate set, using observed plant data, is presented and compared with some classical AQM policy examples, such as Random Early Detection (RED) and fixed PI control. A new cost detectable switching law with an interval cost function switching algorithm, which improves the performance and also saves the computational cost, is developed and compared with a law commonly used in the switching control literature. Finite-gain stability of the system is proved. A fuzzy logic PI controller is incorporated as a special candidate to achieve good performance at all nominal points with the available set of candidate controllers. Simulations are presented to validate the theory. An effocient routing algorithm plays a key role in optimizing network resources. In this thesis, we briefly analyze Low Earth Orbit (LEO) satellite networks, review the Cross Entropy (CE

  11. Dynamic congestion control mechanisms for MPLS networks

    NASA Astrophysics Data System (ADS)

    Holness, Felicia; Phillips, Chris I.

    2001-02-01

    Considerable interest has arisen in congestion control through traffic engineering from the knowledge that although sensible provisioning of the network infrastructure is needed, together with sufficient underlying capacity, these are not sufficient to deliver the Quality of Service required for new applications. This is due to dynamic variations in load. In operational Internet Protocol (IP) networks, it has been difficult to incorporate effective traffic engineering due to the limited capabilities of the IP technology. In principle, Multiprotocol Label Switching (MPLS), which is a connection-oriented label swapping technology, offers new possibilities in addressing the limitations by allowing the operator to use sophisticated traffic control mechanisms. This paper presents a novel scheme to dynamically manage traffic flows through the network by re-balancing streams during periods of congestion. It proposes management-based algorithms that will allow label switched routers within the network to utilize mechanisms within MPLS to indicate when flows are starting to experience frame/packet loss and then to react accordingly. Based upon knowledge of the customer's Service Level Agreement, together with instantaneous flow information, the label edge routers can then instigate changes to the LSP route and circumvent congestion that would hitherto violate the customer contacts.

  12. Signalling and obfuscation for congestion control

    NASA Astrophysics Data System (ADS)

    Mareček, Jakub; Shorten, Robert; Yu, Jia Yuan

    2015-10-01

    We aim to reduce the social cost of congestion in many smart city applications. In our model of congestion, agents interact over limited resources after receiving signals from a central agent that observes the state of congestion in real time. Under natural models of agent populations, we develop new signalling schemes and show that by introducing a non-trivial amount of uncertainty in the signals, we reduce the social cost of congestion, i.e., improve social welfare. The signalling schemes are efficient in terms of both communication and computation, and are consistent with past observations of the congestion. Moreover, the resulting population dynamics converge under reasonable assumptions.

  13. Adapting End Host Congestion Control for Mobility

    NASA Technical Reports Server (NTRS)

    Eddy, Wesley M.; Swami, Yogesh P.

    2005-01-01

    Network layer mobility allows transport protocols to maintain connection state, despite changes in a node's physical location and point of network connectivity. However, some congestion-controlled transport protocols are not designed to deal with these rapid and potentially significant path changes. In this paper we demonstrate several distinct problems that mobility-induced path changes can create for TCP performance. Our premise is that mobility events indicate path changes that require re-initialization of congestion control state at both connection end points. We present the application of this idea to TCP in the form of a simple solution (the Lightweight Mobility Detection and Response algorithm, that has been proposed in the IETF), and examine its effectiveness. In general, we find that the deficiencies presented are both relatively easily and painlessly fixed using this solution. We also find that this solution has the counter-intuitive property of being both more friendly to competing traffic, and simultaneously more aggressive in utilizing newly available capacity than unmodified TCP.

  14. Autonomous Congestion Control in Delay-Tolerant Networks

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott; Jennings, Esther; Schoolcraft, Joshua

    2006-01-01

    Congestion control is an important feature that directly affects network performance. Network congestion may cause loss of data or long delays. Although this problem has been studied extensively in the Internet, the solutions for Internet congestion control do not apply readily to challenged network environments such as Delay Tolerant Networks (DTN) where end-to-end connectivity may not exist continuously and latency can be high. In DTN, end-to-end rate control is not feasible. This calls for congestion control mechanisms where the decisions can be made autonomously with local information only. We use an economic pricing model and propose a rule-based congestion control mechanism where each router can autonomously decide on whether to accept a bundle (data) based on local information such as available storage and the value and risk of accepting the bundle (derived from historical statistics). Preliminary experimental results show that this congestion control mechanism can protect routers from resource depletion without loss of data.

  15. IPTV multicast with peer-assisted lossy error control

    NASA Astrophysics Data System (ADS)

    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.

  16. Autonomous Congestion Control in Delay-Tolerant Networks

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott; Jennings, Esther; Schoolcraft, Joshua

    2006-01-01

    This presentation highlights communication congestion control in delay-tolerant networks (DTNs). Large-scale future space exploration will offer complex communication challenges that may be best addressed by establishing a network infrastructure. However, current internet techniques for congestion control are not well suited for operation of a network over interplanetary distances. An alternative, delay-tolerant technique for congestion control in a delay-tolerant network is presented. A simple DTN was constructed and an experimental congestion control mechanism was applied. The mechanism appeared to be effective and each router was able to make its bundle acceptance decisions autonomously. Future research will examine more complex topologies and alternative bundle acceptance rules that might enhance performance.

  17. On-board congestion control for satellite packet switching networks

    NASA Technical Reports Server (NTRS)

    Chu, Pong P.

    1991-01-01

    It is desirable to incorporate packet switching capability on-board for future communication satellites. Because of the statistical nature of packet communication, incoming traffic fluctuates and may cause congestion. Thus, it is necessary to incorporate a congestion control mechanism as part of the on-board processing to smooth and regulate the bursty traffic. Although there are extensive studies on congestion control for both baseband and broadband terrestrial networks, these schemes are not feasible for space based switching networks because of the unique characteristics of satellite link. Here, we propose a new congestion control method for on-board satellite packet switching. This scheme takes into consideration the long propagation delay in satellite link and takes advantage of the the satellite's broadcasting capability. It divides the control between the ground terminals and satellite, but distributes the primary responsibility to ground terminals and only requires minimal hardware resource on-board satellite.

  18. Abrupt transition to complete congestion on complex networks and control.

    PubMed

    Wang, Wen-Xu; Wu, Zhi-Xi; Jiang, Rui; Chen, Guanrong; Lai, Ying-Cheng

    2009-09-01

    Previous works on traffic-flow dynamics on complex networks have mostly focused on continuous phase transition from a free-flow state to a locally congested state as a parameter, such as the packet-generating rate, is increased through a critical value. Above the transition point congestion occurs on a small subset of nodes. Utilizing a conventional traffic-flow model based on the packet birth-death process and more importantly, taking into account the fact that in realistic networks nodes have only finite buffers, we find an abrupt transition from free flow to complete congestion. Slightly below the transition point, the network can support the maximum amount of traffic for some optimal value of the routing parameter. We develop a mean-field theory to explain the surprising transition phenomenon and provide numerical support. Furthermore, we propose a control strategy based on the idea of random packet dropping to prevent/break complete congestion. Our finding provides insights into realistic communication networks where complete congestion can occur directly from a free-flow state without any apparent precursor, and our control strategy can be effective to restore traffic flow once complete congestion has occurred.

  19. Scheduled Controller Design of Congestion Control Considering Network Resource Constraints

    NASA Astrophysics Data System (ADS)

    Naito, Hiroyuki; Azuma, Takehito; Fujita, Masayuki

    In this paper, we consider a dynamical model of computer networks and derive a synthesis method for congestion control. First, we show a model of TCP/AQM (Transmission Control Protocol/Active Queue Management) as a dynamical model of computer networks. The dynamical model of TCP/AQM networks consists of models of TCP window size, queue length and AQM mechanisms. Second, we propose to describe the dynamical model of TCP/AQM networks as linear systems with self-scheduling parameters, which also depend on information delay. Here we focus on the constraints on the maximum queue length and TCP window-size, which are the network resources in TCP/AQM networks. We derive TCP/AQM networks as the LPV system (linear parameter varying system) with information delay and self-scheduling parameter. We design a memoryless state feedback controller of the LPV system based on a gain-scheduling method. Finally, the effectiveness of the proposed method is evaluated by using MATLAB and the well-known ns-2 (Network Simulator Ver.2) simulator.

  20. A Scalable Media Multicasting Scheme

    NASA Astrophysics Data System (ADS)

    Youwei, Zhang

    IP multicast has been proved to be unfeasible for deployment, Application Layer Multicast (ALM) Based on end multicast system is practical and more scalable than IP multicast in Internet. In this paper, an ALM protocol called Scalable multicast for High Definition streaming media (SHD) is proposed in which end to end transmission capability is fully cultivated for HD media transmission without increasing much control overhead. Similar to the transmission style of BiTtorrent, hosts only forward part of data piece according to the available bandwidth that improves the usage of bandwidth greatly. On the other hand, some novel strategies are adopted to overcome the disadvantages of BiTtorrent protocol in streaming media transmission. Data transmission between hosts is implemented in many-one transmission style in Hierarchical architecture in most circumstances. Simulations implemented on Internet-like topology indicate that SHD achieves low link stress, end to end latency and stability.

  1. RATE-ADJUSTMENT ALGORITHM FOR AGGREGATE TCP CONGESTION CONTROL

    SciTech Connect

    P. TINNAKORNSRISUPHAP, ET AL

    2000-09-01

    The TCP congestion-control mechanism is an algorithm designed to probe the available bandwidth of the network path that TCP packets traverse. However, it is well-known that the TCP congestion-control mechanism does not perform well on networks with a large bandwidth-delay product due to the slow dynamics in adapting its congestion window, especially for short-lived flows. One promising solution to the problem is to aggregate and share the path information among TCP connections that traverse the same bottleneck path, i.e., Aggregate TCP. However, this paper shows via a queueing analysis of a generalized processor-sharing (GPS) queue with regularly-varying service time that a simple aggregation of local TCP connections together into a single aggregate TCP connection can result in a severe performance degradation. To prevent such a degradation, we introduce a rate-adjustment algorithm. Our simulation confirms that by utilizing our rate-adjustment algorithm on aggregate TCP, connections which would normally receive poor service achieve significant performance improvements without penalizing connections which already receive good service.

  2. Autonomous Distributed Congestion Control Scheme in WCDMA Network

    NASA Astrophysics Data System (ADS)

    Ahmad, Hafiz Farooq; Suguri, Hiroki; Choudhary, Muhammad Qaisar; Hassan, Ammar; Liaqat, Ali; Khan, Muhammad Umer

    Wireless technology has become widely popular and an important means of communication. A key issue in delivering wireless services is the problem of congestion which has an adverse impact on the Quality of Service (QoS), especially timeliness. Although a lot of work has been done in the context of RRM (Radio Resource Management), the deliverance of quality service to the end user still remains a challenge. Therefore there is need for a system that provides real-time services to the users through high assurance. We propose an intelligent agent-based approach to guarantee a predefined Service Level Agreement (SLA) with heterogeneous user requirements for appropriate bandwidth allocation in QoS sensitive cellular networks. The proposed system architecture exploits Case Based Reasoning (CBR) technique to handle RRM process of congestion management. The system accomplishes predefined SLA through the use of Retrieval and Adaptation Algorithm based on CBR case library. The proposed intelligent agent architecture gives autonomy to Radio Network Controller (RNC) or Base Station (BS) in accepting, rejecting or buffering a connection request to manage system bandwidth. Instead of simply blocking the connection request as congestion hits the system, different buffering durations are allocated to diverse classes of users based on their SLA. This increases the opportunity of connection establishment and reduces the call blocking rate extensively in changing environment. We carry out simulation of the proposed system that verifies efficient performance for congestion handling. The results also show built-in dynamism of our system to cater for variety of SLA requirements.

  3. Adaptive mechanism-based congestion control for networked systems

    NASA Astrophysics Data System (ADS)

    Liu, Zhi; Zhang, Yun; Chen, C. L. Philip

    2013-03-01

    In order to assure the communication quality in network systems with heavy traffic and limited bandwidth, a new ATRED (adaptive thresholds random early detection) congestion control algorithm is proposed for the congestion avoidance and resource management of network systems. Different to the traditional AQM (active queue management) algorithms, the control parameters of ATRED are not configured statically, but dynamically adjusted by the adaptive mechanism. By integrating with the adaptive strategy, ATRED alleviates the tuning difficulty of RED (random early detection) and shows a better control on the queue management, and achieve a more robust performance than RED under varying network conditions. Furthermore, a dynamic transmission control protocol-AQM control system using ATRED controller is introduced for the systematic analysis. It is proved that the stability of the network system can be guaranteed when the adaptive mechanism is finely designed. Simulation studies show the proposed ATRED algorithm achieves a good performance in varying network environments, which is superior to the RED and Gentle-RED algorithm, and providing more reliable service under varying network conditions.

  4. A reliable multicast for XTP

    NASA Technical Reports Server (NTRS)

    Dempsey, Bert J.; Weaver, Alfred C.

    1990-01-01

    Multicast services needed for current distributed applications on LAN's fall generally into one of three categories: datagram, semi-reliable, and reliable. Transport layer multicast datagrams represent unreliable service in which the transmitting context 'fires and forgets'. XTP executes these semantics when the MULTI and NOERR mode bits are both set. Distributing sensor data and other applications in which application-level error recovery strategies are appropriate benefit from the efficiency in multidestination delivery offered by datagram service. Semi-reliable service refers to multicasting in which the control algorithms of the transport layer--error, flow, and rate control--are used in transferring the multicast distribution to the set of receiving contexts, the multicast group. The multicast defined in XTP provides semi-reliable service. Since, under a semi-reliable service, joining a multicast group means listening on the group address and entails no coordination with other members, a semi-reliable facility can be used for communication between a client and a server group as well as true peer-to-peer group communication. Resource location in a LAN is an important application domain. The term 'semi-reliable' refers to the fact that group membership changes go undetected. No attempt is made to assess the current membership of the group at any time--before, during, or after--the data transfer.

  5. WWW media distribution via Hopwise reliable multicast

    SciTech Connect

    Donnelley, J.E.

    1994-12-01

    Repeated access to WWW pages currently makes inefficient use of available network bandwidth. A Distribution Point Model is proposed where large and relatively static sets of pages (e.g. magazines or other such media) are distributed via bulk multicast to LAN distribution points for local access. Some access control issues are discussed. Hopwise Reliable Multicast (HRM) is proposed to simplify reliable multicast of non real time bulk data between LANs. HRM uses TCP for reliability and flow control on a hop by hop basis throughout a multicast distribution tree created by today`s Internet MBone.

  6. Software-defined control-plane for wavelength selective unicast and multicast of optical data in a silicon photonic platform.

    PubMed

    Gazman, Alexander; Browning, Colm; Bahadori, Meisam; Zhu, Ziyi; Samadi, Payman; Rumley, Sébastien; Vujicic, Vidak; Barry, Liam P; Bergman, Keren

    2017-01-09

    We demonstrate a programmable control-plane based on field programmable gate array (FPGA) with a power-efficient algorithm for optical unicast, multicast, and broadcast functionalities in a silicon photonic platform. The platform includes a silicon photonic 1×8 microring array chip which in conjunction with a fast tunable laser over the C-band is capable of delivering software controlled wavelength selective functionality on top of spatial switching. We characterize the thermo-optic response of microring resonators and extract key parameters necessary for the development of the control-plane. The performance of the proposed architecture is tested with 10 Gb/s on-off keying (OOK) optical data and error-free operation is verified for various wavelength and spatial switching scenarios. Lastly, we evaluate electrical power and energy consumption required to reconfigure the silicon photonic device for all possible wavelength operations and output ports combinations and show that unicast, multicast of two, three, four, five, six, seven, and broadcast functions are achieved with energy overheads of 0.02, 0.07, 0.18, 0.49, 0.76, 1.01, 1.3, and 1.55 pJ/bit, respectively.

  7. Robust ?dynamic output feedback control of networked control systems with congestion control

    NASA Astrophysics Data System (ADS)

    Rasool, Faiz; Kiong Ngaung, Sing

    2015-07-01

    This paper investigates a robust ?dynamic output feedback controller for networked control systems (NCSs) with a simple congestion control scheme. This scheme enables the NCSs design to enjoy advantages of both time-triggered and event-triggered systems. The proposed scheme compares current measurement with last transmitted measurement. If difference between them is less than a prescribed percentage of the current measurements then no measurement is transmitted to controller and the controller always uses the last transmitted measurements to calculate feedback gains. Moreover, this technique is applied to controller output as well. The stability criteria for closed-loop system is formulated using the Lyapunov-Krasovskii functional approach. The sufficient conditions for the controller are given in terms of solvability of bilinear matrix inequalities (BMIs). These BMIs are converted into quasi-convex linear matrix inequalities that are solved using the cone complementarity linearisation algorithm. A simulation example is used to evaluate how effective the simple congestion control scheme is in reducing network bandwidth.

  8. Issues in designing transport layer multicast facilities

    NASA Technical Reports Server (NTRS)

    Dempsey, Bert J.; Weaver, Alfred C.

    1990-01-01

    Multicasting denotes a facility in a communications system for providing efficient delivery from a message's source to some well-defined set of locations using a single logical address. While modem network hardware supports multidestination delivery, first generation Transport Layer protocols (e.g., the DoD Transmission Control Protocol (TCP) (15) and ISO TP-4 (41)) did not anticipate the changes over the past decade in underlying network hardware, transmission speeds, and communication patterns that have enabled and driven the interest in reliable multicast. Much recent research has focused on integrating the underlying hardware multicast capability with the reliable services of Transport Layer protocols. Here, we explore the communication issues surrounding the design of such a reliable multicast mechanism. Approaches and solutions from the literature are discussed, and four experimental Transport Layer protocols that incorporate reliable multicast are examined.

  9. Algorithm and data support of traffic congestion forecasting in the controlled transport

    NASA Astrophysics Data System (ADS)

    Dmitriev, S. V.

    2015-06-01

    The topicality of problem of the traffic congestion forecasting in the logistic systems of product movement highways is considered. The concepts: the controlled territory, the highway occupancy by vehicles, the parking and the controlled territory are introduced. Technical realizabilityof organizing the necessary flow of information on the state of the transport system for its regulation has been marked. Sequence of practical implementation of the solution is given. An algorithm for predicting traffic congestion in the controlled transport system is suggested.

  10. Congestion Control and Fairness in Wireless Sensor Networks

    DTIC Science & Technology

    2010-04-01

    RCRT uses end-to-end explicit loss recovery by implementing a NACK based scheme. Furthermore, RCRT places all congestion detection and rate...gateway nodes, we make use of the broadcast nature of the wireless medium, which enables a child node to overhear transmissions of its parent. When...the broadcast nature of the wireless medium, enabling a child node to overhear transmission of its parent. Thus, when the minimum bandwidth

  11. Point-to-Point Multicast Communications Protocol

    NASA Technical Reports Server (NTRS)

    Byrd, Gregory T.; Nakano, Russell; Delagi, Bruce A.

    1987-01-01

    This paper describes a protocol to support point-to-point interprocessor communications with multicast. Dynamic, cut-through routing with local flow control is used to provide a high-throughput, low-latency communications path between processors. In addition multicast transmissions are available, in which copies of a packet are sent to multiple destinations using common resources as much as possible. Special packet terminators and selective buffering are introduced to avoid a deadlock during multicasts. A simulated implementation of the protocol is also described.

  12. Congestion and flow control in signaling system No. 7: Impacts of intelligent networks and new services

    SciTech Connect

    Zepf, J.; Rufa, G. )

    1994-04-01

    This paper focuses on the transient performance analysis of the congestion and flow control mechanisms in CCITT Signaling System No. 7 (SS7). Special attention is directed to the impacts of the introduction of intelligent services and new applications, e.g., Freephone, credit card services, user-to-user signaling, etc. In particular, we show that signaling traffic characteristics like signaling scenarios or signaling message length as well as end-to-end signaling capabilities have a significant influence on the congestion and flow control and, therefore, on the real-time signaling performance. One important result of our performance studies is that if, e.g., intelligent services are introduced, the SS7 congestion and flow control does not work correctly. To solve this problem, some reinvestigations into these mechanisms would be necessary. Therefore, some approaches, e.g., modification of the Signaling Connection Control Part (SCCP) congestion control, usage of the SCCP relay function, or a redesign of the MTP flow control procedures are discussed in order to guarantee the efficacy of the congestion and flow control mechanisms also in the future. 16 refs.

  13. Congestion and flow control in signaling system no. 7: Impacts of intelligent networks and new services

    NASA Astrophysics Data System (ADS)

    Zepf, Joachim; Rufa, Gerhard

    1994-04-01

    This paper focuses on the transient performance analysis of the congestion and flow control mechanisms in CCITT Signaling System No. 7 (SS7). Special attention is directed to the impacts of the introduction of intelligent services and new applications, e.g., Freephone, credit card services, user-to-user signaling, etc. In particular, we show that signaling traffic characteristics like signaling scenarios or signaling message length as well as end-to-end signaling capabilities have a significant influence on the congestion and flow control and, therefore, on the real-time signaling performance. One important result of our performance studies is that if, e.g., intelligent services are introduced, the SS7 congestion and flow control does not work correctly. To solve this problem, some reinvestigations into these mechanisms would be necessary. Therefore, some approaches, e.g., modification of the Signaling Connection Control Part (SCCP) congestion control, usage of the SCCP relay function, or a redesign of the MTP flow control procedures are discussed in order to guarantee the efficacy of the congestion and flow control mechanisms also in the future.

  14. The congestion control algorithm based on queue management of each node in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Wei, Yifei; Chang, Lin; Wang, Yali; Wang, Gaoping

    2016-12-01

    This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. As the network load increases, local congestion of mobile ad hoc network may lead to network performance degradation, hot node's energy consumption increase even failure. If small energy nodes congested because of forwarding data packets, then when it is used as the source node will cause a lot of packet loss. This paper proposes an active queue management mechanism, considering the node's own ability and its importance in the network to set the queue threshold. Controlling nodes buffer queue in different levels of congestion area probability by adjusting the upper limits and lower limits, thus nodes can adjust responsibility of forwarding data packets according to their own situation. The proposed algorithm will slow down the send rate hop by hop along the data package transmission direction from congestion node to source node so that to prevent further congestion from the source node. The simulation results show that, the algorithm can better play the data forwarding ability of strong nodes, protect the weak nodes, can effectively alleviate the network congestion situation.

  15. Application Layer Multicast

    NASA Astrophysics Data System (ADS)

    Allani, Mouna; Garbinato, Benoît; Pedone, Fernando

    An increasing number of Peer-to-Peer (P2P) Internet applications rely today on data dissemination as their cornerstone, e.g., audio or video streaming, multi-party games. These applications typically depend on some support for multicast communication, where peers interested in a given data stream can join a corresponding multicast group. As a consequence, the efficiency, scalability, and reliability guarantees of these applications are tightly coupled with that of the underlying multicast mechanism.

  16. Priority Based Congestion Control Dynamic Clustering Protocol in Mobile Wireless Sensor Networks.

    PubMed

    Jayakumari, R Beulah; Senthilkumar, V Jawahar

    2015-01-01

    Wireless sensor network is widely used to monitor natural phenomena because natural disaster has globally increased which causes significant loss of life, economic setback, and social development. Saving energy in a wireless sensor network (WSN) is a critical factor to be considered. The sensor nodes are deployed to sense, compute, and communicate alerts in a WSN which are used to prevent natural hazards. Generally communication consumes more energy than sensing and computing; hence cluster based protocol is preferred. Even with clustering, multiclass traffic creates congested hotspots in the cluster, thereby causing packet loss and delay. In order to conserve energy and to avoid congestion during multiclass traffic a novel Priority Based Congestion Control Dynamic Clustering (PCCDC) protocol is developed. PCCDC is designed with mobile nodes which are organized dynamically into clusters to provide complete coverage and connectivity. PCCDC computes congestion at intra- and intercluster level using linear and binary feedback method. Each mobile node within the cluster has an appropriate queue model for scheduling prioritized packet during congestion without drop or delay. Simulation results have proven that packet drop, control overhead, and end-to-end delay are much lower in PCCDC which in turn significantly increases packet delivery ratio, network lifetime, and residual energy when compared with PASCC protocol.

  17. Priority Based Congestion Control Dynamic Clustering Protocol in Mobile Wireless Sensor Networks

    PubMed Central

    Beulah Jayakumari, R.; Jawahar Senthilkumar, V.

    2015-01-01

    Wireless sensor network is widely used to monitor natural phenomena because natural disaster has globally increased which causes significant loss of life, economic setback, and social development. Saving energy in a wireless sensor network (WSN) is a critical factor to be considered. The sensor nodes are deployed to sense, compute, and communicate alerts in a WSN which are used to prevent natural hazards. Generally communication consumes more energy than sensing and computing; hence cluster based protocol is preferred. Even with clustering, multiclass traffic creates congested hotspots in the cluster, thereby causing packet loss and delay. In order to conserve energy and to avoid congestion during multiclass traffic a novel Priority Based Congestion Control Dynamic Clustering (PCCDC) protocol is developed. PCCDC is designed with mobile nodes which are organized dynamically into clusters to provide complete coverage and connectivity. PCCDC computes congestion at intra- and intercluster level using linear and binary feedback method. Each mobile node within the cluster has an appropriate queue model for scheduling prioritized packet during congestion without drop or delay. Simulation results have proven that packet drop, control overhead, and end-to-end delay are much lower in PCCDC which in turn significantly increases packet delivery ratio, network lifetime, and residual energy when compared with PASCC protocol. PMID:26504898

  18. Input-Output Modeling and Control of the Departure Process of Congested Airports

    NASA Technical Reports Server (NTRS)

    Pujet, Nicolas; Delcaire, Bertrand; Feron, Eric

    2003-01-01

    A simple queueing model of busy airport departure operations is proposed. This model is calibrated and validated using available runway configuration and traffic data. The model is then used to evaluate preliminary control schemes aimed at alleviating departure traffic congestion on the airport surface. The potential impact of these control strategies on direct operating costs, environmental costs and overall delay is quantified and discussed.

  19. Infinite horizon optimal impulsive control with applications to Internet congestion control

    NASA Astrophysics Data System (ADS)

    Avrachenkov, Konstantin; Habachi, Oussama; Piunovskiy, Alexey; Zhang, Yi

    2015-04-01

    We investigate infinite-horizon deterministic optimal control problems with both gradual and impulsive controls, where any finitely many impulses are allowed simultaneously. Both discounted and long-run time-average criteria are considered. We establish very general and at the same time natural conditions, under which the dynamic programming approach results in an optimal feedback policy. The established theoretical results are applied to the Internet congestion control, and by solving analytically and nontrivially the underlying optimal control problems, we obtain a simple threshold-based active queue management scheme, which takes into account the main parameters of the transmission control protocols, and improves the fairness among the connections in a given network.

  20. CCS_WHMS: A Congestion Control Scheme for Wearable Health Management System.

    PubMed

    Kafi, Mohamed Amine; Ben Othman, Jalel; Bagaa, Miloud; Badache, Nadjib

    2015-12-01

    Wearable computing is becoming a more and more attracting field in the last years thanks to the miniaturisation of electronic devices. Wearable healthcare monitoring systems (WHMS) as an important client of wearable computing technology has gained a lot. Indeed, the wearable sensors and their surrounding healthcare applications bring a lot of benefits to patients, elderly people and medical staff, so facilitating their daily life quality. But from a research point of view, there is still work to accomplish in order to overcome the gap between hardware and software parts. In this paper, we target the problem of congestion control when all these healthcare sensed data have to reach the destination in a reliable manner that avoids repetitive transmission which wastes precious energy or leads to loss of important information in emergency cases, too. We propose a congestion control scheme CCS_WHMS that ensures efficient and fair data delivery while used in the body wearable system part or in the multi-hop inter bodies wearable ones to get the destination. As the congestion detection paradigm is very important in the control process, we do experimental tests to compare between state of the art congestion detection methods, using MICAz motes, in order to choose the appropriate one for our scheme.

  1. Cross-layer active predictive congestion control protocol for wireless sensor networks.

    PubMed

    Wan, Jiangwen; Xu, Xiaofeng; Feng, Renjian; Wu, Yinfeng

    2009-01-01

    In wireless sensor networks (WSNs), there are numerous factors that may cause network congestion problems, such as the many-to-one communication modes, mutual interference of wireless links, dynamic changes of network topology and the memory-restrained characteristics of nodes. All these factors result in a network being more vulnerable to congestion. In this paper, a cross-layer active predictive congestion control scheme (CL-APCC) for improving the performance of networks is proposed. Queuing theory is applied in the CL-APCC to analyze data flows of a single-node according to its memory status, combined with the analysis of the average occupied memory size of local networks. It also analyzes the current data change trends of local networks to forecast and actively adjust the sending rate of the node in the next period. In order to ensure the fairness and timeliness of the network, the IEEE 802.11 protocol is revised based on waiting time, the number of the node's neighbors and the original priority of data packets, which dynamically adjusts the sending priority of the node. The performance of CL-APCC, which is evaluated by extensive simulation experiments. is more efficient in solving the congestion in WSNs. Furthermore, it is clear that the proposed scheme has an outstanding advantage in terms of improving the fairness and lifetime of networks.

  2. Development of potential methods for testing congestion control algorithm implemented in vehicle to vehicle communications.

    PubMed

    Hsu, Chung-Jen; Fikentscher, Joshua; Kreeb, Robert

    2017-03-21

    Objective A channel congestion problem might occur when the traffic density increases since the number of basic safety messages carried on the communication channel also increases in vehicle-to-vehicle communications. A remedy algorithm proposed in SAE J2945/1 is designed to address the channel congestion issue by decreasing transmission frequency and radiated power. This study is to develop potential test procedures for evaluating or validating the congestion control algorithm. Methods Simulations of a reference unit transmitting at a higher frequency are implemented to emulate a number of Onboard Equipment (OBE) transmitting at the normal interval of 100 milliseconds (10 Hz). When the transmitting interval is reduced to 1.25 milliseconds (800 Hz), the reference unit emulates 80 vehicles transmitting at 10 Hz. By increasing the number of reference units transmitting at 800 Hz in the simulations, the corresponding channel busy percentages are obtained. An algorithm for GPS data generation of virtual vehicles is developed for facilitating the validation of transmission intervals in the congestion control algorithm. Results Channel busy percentage is the channel busy time over a specified period of time. Three or four reference units are needed to generate channel busy percentages between 50% and 80%, and five reference units can generate channel busy percentages above 80%. The proposed test procedures can verify the operation of congestion control algorithm when channel busy percentages are between 50% and 80%, and above 80%. By using GPS data generation algorithm, the test procedures can also verify the transmission intervals when traffic densities are 80 and 200 vehicles in the radius of 100 m. A suite of test tools with functional requirements is also proposed for facilitating the implementation of test procedures. Conclusions The potential test procedures for congestion control algorithm are developed based on the simulation results of channel busy

  3. Controlling satellite communication system unwanted emissions in congested RF spectrum

    NASA Astrophysics Data System (ADS)

    Olsen, Donald; Heymann, Roger

    2007-09-01

    The International Telecommunication Union (ITU), a United Nations (UN) agency, is the agency that, under an international treaty, sets radio spectrum usage regulations among member nations. Within the United States of America (USA), the organization that sets regulations, coordinates an application for use, and provides authorization for federal government/agency use of the radio frequency (RF) spectrum is the National Telecommunications and Information Administration (NTIA). In this regard, the NTIA defines which RF spectrum is available for federal government use in the USA, and how it is to be used. The NTIA is a component of the United States (U.S.) Department of Commerce of the federal government. The significance of ITU regulations is that ITU approval is required for U.S. federal government/agency permission to use the RF spectrum outside of U.S. boundaries. All member nations have signed a treaty to do so. U.S. federal regulations for federal use of the RF spectrum are found in the Manual of Regulations and Procedures for Federal Radio Frequency Management, and extracts of the manual are found in what is known as the Table of Frequency Allocations. Nonfederal government and private sector use of the RF spectrum within the U.S. is regulated by the Federal Communications Commission (FCC). There is a need to control "unwanted emissions" (defined to include out-of-band emissions, which are those immediately adjacent to the necessary and allocated bandwidth, plus spurious emissions) to preclude interference to all other authorized users. This paper discusses the causes, effects, and mitigation of unwanted RF emissions to systems in adjacent spectra. Digital modulations are widely used in today's satellite communications. Commercial communications sector standards are covered for the most part worldwide by Digital Video Broadcast - Satellite (DVB-S) and digital satellite news gathering (DSNG) evolutions and the second generation of DVB-S (DVB-S2) standard

  4. Implementation of the Algorithm for Congestion control in the Dynamic Circuit Network (DCN)

    NASA Astrophysics Data System (ADS)

    Nalamwar, H. S.; Ivanov, M. A.; Buddhawar, G. U.

    2017-01-01

    Transport Control Protocol (TCP) incast congestion happens when a number of senders work in parallel with the same server where the high bandwidth and low latency network problem occurs. For many data center network applications such as a search engine, heavy traffic is present on such a server. Incast congestion degrades the entire performance as packets are lost at a server side due to buffer overflow, and as a result, the response time becomes longer. In this work, we focus on TCP throughput, round-trip time (RTT), receive window and retransmission. Our method is based on the proactive adjust of the TCP receive window before the packet loss occurs. We aim to avoid the wastage of the bandwidth by adjusting its size as per the number of packets. To avoid the packet loss, the ICTCP algorithm has been implemented in the data center network (ToR).

  5. Road Traffic Control Based on Genetic Algorithm for Reducing Traffic Congestion

    NASA Astrophysics Data System (ADS)

    Shigehiro, Yuji; Miyakawa, Takuya; Masuda, Tatsuya

    In this paper, we propose a road traffic control method for reducing traffic congestion with genetic algorithm. In the not too distant future, the system which controls the routes of all vehicles in a certain area must be realized. The system should optimize the routes of all vehicles, however the solution space of this problem is enormous. Therefore we apply the genetic algorithm to this problem, by encoding the route of all vehicles to a fixed length chromosome. To improve the search performance, a new genetic operator called “path shortening” is also designed. The effectiveness of the proposed method is shown by the experiment.

  6. Design of proportional-derivative-type state feedback controllers for congestion control of transmission control protocol networks

    NASA Astrophysics Data System (ADS)

    Azadegan, Masoumeh; Beheshti, Mohammad T. H.; Tavassoli, Babak

    2015-07-01

    A new proportional-derivative-type state feedback controller is proposed for congestion control of transmission control protocol (TCP) networks. An analytical TCP model is adopted. In the proposed control scheme, it is possible to efficiently control the TCP traffic using only the queue length at the router without the need to know the TCP window size which is not available locally. The results are presented in terms of delay-dependent linear matrix inequality. The proposed method is verified by simulation examples using NS software, and the effectiveness and superiority of our method over other control schemes, such as the proportional-integral, random early detection and generalised minimum variancemethods, are also shown.

  7. Fast causal multicast

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.; Schiper, Andre; Stephenson, Pat

    1990-01-01

    A new protocol is presented that efficiently implements a reliable, causally ordered multicast primitive and is easily extended into a totally ordered one. Intended for use in the ISIS toolkit, it offers a way to bypass the most costly aspects of ISIS while benefiting from virtual synchrony. The facility scales with bounded overhead. Measured speedups of more than an order of magnitude were obtained when the protocol was implemented within ISIS. One conclusion is that systems such as ISIS can achieve performance competitive with the best existing multicast facilities - a finding contradicting the widespread concern that fault-tolerance may be unacceptably costly.

  8. Fast casual multicast

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth; Schiper, Andre; Stephenson, Pat

    1990-01-01

    A new protocol is presented that efficiently implements a reliable, causally ordered multicast primitive and is easily extended into a totally ordered one. Intended for use in the ISIS toolkit, it offers a way to bypass the most costly aspects of ISIS while benefiting from virtual synchrony. The facility scales with bounded overhead. Measured speedups of more than an order of magnitude were obtained when the protocol was implemented within ISIS. One conclusion is that systems such as ISIS can achieve performance competitive with the best existing multicast facilities--a finding contradicting the widespread concern that fault-tolerance may be unacceptably costly.

  9. Evaluation of TCP Congestion Control Algorithms on the Windows Vista Platform

    SciTech Connect

    Li, Yee-Ting; /SLAC

    2006-07-07

    CTCP, an innovative TCP congestion control algorithm developed by Microsoft, is evaluated and compared to HSTCP and StandardTCP. Tests were performed on the production Internet from Stanford Linear Accelerator Center (SLAC) to various geographically located hosts to give a broad overview of the performances. We find that certain issues were apparent during testing (not directly related to the congestion control algorithms) which may skew results. With this in mind, we find that CTCP performed similarly to HSTCP across a multitude of different network environments. However, to improve the fairness and to reduce the impact of CTCP upon existing StandardTCP traffic, two areas of further research were investigated. Algorithmic additions to CTCP for burst control to reduce the aggressiveness of its cwnd increments demonstrated beneficial improvements in both fairness and throughput over the original CTCP algorithm. Similarly, {gamma} auto-tuning algorithms were investigated to dynamically adapt CTCP flows to their network conditions for optimal performance. While the effects of these auto-tuning algorithms when used in addition to burst control showed little to no benefit to fairness nor throughput for the limited number of network paths tested, one of the auto-tuning algorithms performed such that there was negligible impact upon StandardTCP. With these improvements, CTCP was found to perform better than HSTCP in terms of fairness and similarly in terms of throughput under the production environments tested.

  10. SDTCP: Towards Datacenter TCP Congestion Control with SDN for IoT Applications

    PubMed Central

    Lu, Yifei; Ling, Zhen; Zhu, Shuhong; Tang, Ling

    2017-01-01

    The Internet of Things (IoT) has gained popularity in recent years. Today’s IoT applications are now increasingly deployed in cloud platforms to perform Big Data analytics. In cloud data center networks (DCN), TCP incast usually happens when multiple senders simultaneously communicate with a single receiver. However, when TCP incast happens, DCN may suffer from both throughput collapse for TCP burst flows and temporary starvation for TCP background flows. In this paper, we propose a software defined network (SDN)-based TCP congestion control mechanism, referred to as SDTCP, to leverage the features, e.g., centralized control methods and the global view of the network, in order to solve the TCP incast problems. When we detect network congestion on an OpenFlow switch, our controller can select the background flows and reduce their bandwidth by adjusting the advertised window of TCP ACK packets of the corresponding background flows so as to reserve more bandwidth for burst flows. SDTCP is transparent to the end systems and can accurately decelerate the rate of background flows by leveraging the global view of the network gained via SDN. The experiments demonstrate that our SDTCP can provide high tolerance for burst flows and achieve better flow completion time for short flows. Therefore, SDTCP is an effective and scalable solution for the TCP incast problem. PMID:28075347

  11. SDTCP: Towards Datacenter TCP Congestion Control with SDN for IoT Applications.

    PubMed

    Lu, Yifei; Ling, Zhen; Zhu, Shuhong; Tang, Ling

    2017-01-08

    The Internet of Things (IoT) has gained popularity in recent years. Today's IoT applications are now increasingly deployed in cloud platforms to perform Big Data analytics. In cloud data center networks (DCN), TCP incast usually happens when multiple senders simultaneously communicate with a single receiver. However, when TCP incast happens, DCN may suffer from both throughput collapse for TCP burst flows and temporary starvation for TCP background flows. In this paper, we propose a software defined network (SDN)-based TCP congestion control mechanism, referred to as SDTCP, to leverage the features, e.g., centralized control methods and the global view of the network, in order to solve the TCP incast problems. When we detect network congestion on an OpenFlow switch, our controller can select the background flows and reduce their bandwidth by adjusting the advertised window of TCP ACK packets of the corresponding background flows so as to reserve more bandwidth for burst flows. SDTCP is transparent to the end systems and can accurately decelerate the rate of background flows by leveraging the global view of the network gained via SDN. The experiments demonstrate that our SDTCP can provide high tolerance for burst flows and achieve better flow completion time for short flows. Therefore, SDTCP is an effective and scalable solution for the TCP incast problem.

  12. Congestion Control for a Fair Packet Delivery in WSN: From a Complex System Perspective

    PubMed Central

    2014-01-01

    In this work, we propose that packets travelling across a wireless sensor network (WSN) can be seen as the active agents that make up a complex system, just like a bird flock or a fish school, for instance. From this perspective, the tools and models that have been developed to study this kind of systems have been applied. This is in order to create a distributed congestion control based on a set of simple rules programmed at the nodes of the WSN. Our results show that it is possible to adapt the carried traffic to the network capacity, even under stressing conditions. Also, the network performance shows a smooth degradation when the traffic goes beyond a threshold which is settled by the proposed self-organized control. In contrast, without any control, the network collapses before this threshold. The use of the proposed solution provides an effective strategy to address some of the common problems found in WSN deployment by providing a fair packet delivery. In addition, the network congestion is mitigated using adaptive traffic mechanisms based on a satisfaction parameter assessed by each packet which has impact on the global satisfaction of the traffic carried by the WSN. PMID:25177722

  13. Congestion control for a fair packet delivery in WSN: from a complex system perspective.

    PubMed

    Aguirre-Guerrero, Daniela; Marcelín-Jiménez, Ricardo; Rodriguez-Colina, Enrique; Pascoe-Chalke, Michael

    2014-01-01

    In this work, we propose that packets travelling across a wireless sensor network (WSN) can be seen as the active agents that make up a complex system, just like a bird flock or a fish school, for instance. From this perspective, the tools and models that have been developed to study this kind of systems have been applied. This is in order to create a distributed congestion control based on a set of simple rules programmed at the nodes of the WSN. Our results show that it is possible to adapt the carried traffic to the network capacity, even under stressing conditions. Also, the network performance shows a smooth degradation when the traffic goes beyond a threshold which is settled by the proposed self-organized control. In contrast, without any control, the network collapses before this threshold. The use of the proposed solution provides an effective strategy to address some of the common problems found in WSN deployment by providing a fair packet delivery. In addition, the network congestion is mitigated using adaptive traffic mechanisms based on a satisfaction parameter assessed by each packet which has impact on the global satisfaction of the traffic carried by the WSN.

  14. Multicast traffic grooming in flexible optical WDM networks

    NASA Astrophysics Data System (ADS)

    Patel, Ankitkumar N.; Ji, Philip N.; Jue, Jason P.; Wang, Ting

    2012-12-01

    In Metropolitan Area Networks (MANs), point-to-multipoint applications, such as IPTV, video-on-demand, distance learning, and content distribution, can be efficiently supported through light-tree-based multicastcommunications instead of lightpath-based unicast-communications. The application of multicasting for such traffic is justified by its inherent benefits of reduced control and management overhead and elimination of redundant resource provisioning. Supporting such multicast traffic in Flexible optical WDM (FWDM) networks that can provision light-trees using optimum amount of spectrum within flexible channel spacing leads to higher wavelength and spectral efficiencies compared to the conventional ITU-T fixed grid networks. However, in spite of such flexibility, the residual channel capacity of stranded channels may not be utilized if the network does not offer channels with arbitrary line rates. Additionally, the spectrum allocated to guard bands used to isolate finer granularity channels remains unutilized. These limitations can be addressed by using traffic grooming in which low-rate multicast connections are aggregated and switched over high capacity light-trees. In this paper, we address the multicast traffic grooming problem in FWDM networks, and propose a novel auxiliary graph-based algorithm for the first time. The performance of multicast traffic grooming is evaluated in terms of spectral, cost, and energy efficiencies compared to lightpath-based transparent FWDM networks, lightpathbased traffic grooming-capable FWDM networks, multicast-enabled transparent FWDM networks, and multicast traffic grooming-capable fixed grid networks. Simulation results demonstrate that multicast traffic grooming in FWDM networks not only improves spectral efficiency, but also cost, and energy efficiencies compared to other multicast traffic provisioning approaches of FWDM and fixed grid networks.

  15. Improving Area Control Error Diversity Interchange (ADI) Program by Incorporating Congestion Constraints

    SciTech Connect

    Zhou, Ning; Etingov, Pavel V.; Makarov, Yuri V.; Guttromson, Ross T.; McManus, Bart

    2010-04-30

    The area control error (ACE) determines how much a balancing authority (BA) needs to move its regulating units to meet mandatory control performance standard requirements. Regulation is an expensive resource that could cost several hundred million dollars a year for a BA. The amount of regulation needed in a system is increasing with more intermittent generation resources added to the system. The ACE diversity interchange (ADI) program provides a tool for reducing the regulation requirement by combining ACEs from several participating BAs followed by sharing the total ACE among all participating balancing areas. The effect is achieved as a result of the low statistical correlation between the original ACEs of participating BAs. A rule-based ADI approach has already been put into practice in the US Western Interconnection. The degree of actual ACE sharing is artificially limited because of the unknown redistribution of power flows and possible system congestion (these factors are not monitored in the existing ADI). This paper proposes a two-step linear programming (LP) ADI approach that incorporates congestion constraints. In the first step of the proposed LP ADI, the line transmission limits are enforced by setting up corresponding constraints. In the second step, the business fairness is pursued. Simulation is performed to compare the properties of the proposed LP ADI and the existing rule-based ADI. Favorable features, such as avoiding line limit violations and increasing the degree of possible ACE sharing, are observed for the proposed LP ADI.

  16. A tool for debugging internet multicast routing

    SciTech Connect

    Agarwal, D.; Floyd, S.

    1994-03-01

    In this paper the authors describe a debugging tool that is an effective means of analyzing problems with multicast packet routing in a network. Multicast packet routing is a source-driven distributed calculation performed by the routers in a multicast network. The routes taken by multicast packets are difficult to predict manually due to the large number of variables that must be considered. The multicast route debugging tool allows off-line investigation of the route taken by a multicast packet and the effects of network modifications on that route. The tool has already proved useful in debugging the problems that have occurred in the experimental Internet Multicast Backbone. The multicast route debugging tool currently predicts multicast routes of packets using the distance-vector truncated-broadcast algorithm implemented for Internet multicast traffic. They will be upgrading the tool to allow the user to choose other multicast routing algorithms.

  17. On-board closed-loop congestion control for satellite based packet switching networks

    NASA Technical Reports Server (NTRS)

    Chu, Pong P.; Ivancic, William D.; Kim, Heechul

    1993-01-01

    NASA LeRC is currently investigating a satellite architecture that incorporates on-board packet switching capability. Because of the statistical nature of packet switching, arrival traffic may fluctuate and thus it is necessary to integrate congestion control mechanism as part of the on-board processing unit. This study focuses on the closed-loop reactive control. We investigate the impact of the long propagation delay on the performance and propose a scheme to overcome the problem. The scheme uses a global feedback signal to regulate the packet arrival rate of ground stations. In this scheme, the satellite continuously broadcasts the status of its output buffer and the ground stations respond by selectively discarding packets or by tagging the excessive packets as low-priority. The two schemes are evaluated by theoretical queuing analysis and simulation. The former is used to analyze the simplified model and to determine the basic trends and bounds, and the later is used to assess the performance of a more realistic system and to evaluate the effectiveness of more sophisticated control schemes. The results show that the long propagation delay makes the closed-loop congestion control less responsive. The broadcasted information can only be used to extract statistical information. The discarding scheme needs carefully-chosen status information and reduction function, and normally requires a significant amount of ground discarding to reduce the on-board packet loss probability. The tagging scheme is more effective since it tolerates more uncertainties and allows a larger margin of error in status information. It can protect the high-priority packets from excessive loss and fully utilize the downlink bandwidth at the same time.

  18. Predictive functional control for active queue management in congested TCP/IP networks.

    PubMed

    Bigdeli, N; Haeri, M

    2009-01-01

    Predictive functional control (PFC) as a new active queue management (AQM) method in dynamic TCP networks supporting explicit congestion notification (ECN) is proposed. The ability of the controller in handling system delay along with its simplicity and low computational load makes PFC a privileged AQM method in the high speed networks. Besides, considering the disturbance term (which represents model/process mismatches, external disturbances, and existing noise) in the control formulation adds some level of robustness into the PFC-AQM controller. This is an important and desired property in the control of dynamically-varying computer networks. In this paper, the controller is designed based on a small signal linearized fluid-flow model of the TCP/AQM networks. Then, closed-loop transfer function representation of the system is derived to analyze the robustness with respect to the network and controller parameters. The analytical as well as the packet-level ns-2 simulation results show the out-performance of the developed controller for both queue regulation and resource utilization. Fast response, low queue fluctuations (and consequently low delay jitter), high link utilization, good disturbance rejection, scalability, and low packet marking probability are other features of the developed method with respect to other well-known AQM methods such as RED, PI, and REM which are also simulated for comparison.

  19. Overload Control for Signaling Congestion of Machine Type Communications in 3GPP Networks

    PubMed Central

    Lu, Zhaoming; Pan, Qi; Wang, Luhan; Wen, Xiangming

    2016-01-01

    Because of the limited resources on radio access channels of third generation partnership projection (3GPP) network, one of the most challenging tasks posted by 3GPP cellular-based machine type communications (MTC) is congestion due to massive requests for connection to radio access network (RAN). In this paper, an overload control algorithm in 3GPP RAN is proposed, which proactively disperses the simultaneous access attempts in evenly distributed time window. Through periodic reservation strategy, massive access requests of MTC devices are dispersed in time, which reduces the probability of confliction of signaling. By the compensation and prediction mechanism, each device can communicate with MTC server with dynamic load of air interface. Numerical results prove that proposed method makes MTC applications friendly to 3GPP cellular network. PMID:27936011

  20. Multicast Parametric Synchronous Sampling

    DTIC Science & Technology

    2011-09-01

    construction, four -photon mixing 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT: SAR 18. NUMBER OF PAGES 34 19a. NAME OF...signal and idler pairs. Both of the stated reasons are highly beneficial for efficient cascaded four -wave mixing, which results in a far reaching...the original signal (i.e. before multicasting). (a) Input (b) Compression Stage Output (c) Mixing Stage Output A m p lit u d e [ a .u .] Time [ ps

  1. Rate-based congestion control in networks with smart links, revision. B.S. Thesis - May 1988

    NASA Technical Reports Server (NTRS)

    Heybey, Andrew Tyrrell

    1990-01-01

    The author uses a network simulator to explore rate-based congestion control in networks with smart links that can feed back information to tell senders to adjust their transmission rates. This method differs in a very important way from congestion control in which a congested network component just drops packets - the most commonly used method. It is clearly advantageous for the links in the network to communicate with the end users about the network capacity, rather than the users unilaterally picking a transmission rate. The components in the middle of the network, not the end users, have information about the capacity and traffic in the network. The author experiments with three different algorithms for calculating the control rate to feed back to the users. All of the algorithms exhibit problems in the form of large queues when simulated with a configuration modeling the dynamics of a packet-voice system. However, the problems are not with the algorithms themselves, but with the fact that feedback takes time. If the network steady-state utilization is low enough that it can absorb transients in the traffic through it, then the large queues disappear. If the users are modified to start sending slowly, to allow the network to adapt to a new flow without causing congestion, a greater portion of the network's bandwidth can be used.

  2. Secure Hierarchical Multicast Routing and Multicast Internet Anonymity

    DTIC Science & Technology

    1998-06-01

    the target of the attack. When these 1Internet Group Management Protocol ( IGMP ) [24] is the protocol that hosts uses to communicate with an attached...receives an IGMP [24] message from a subnet requesting the multicast. This physical router sends a join request to some border router of its domain and...process is illustrated in Figure 2.8. When the single router in the A domain receives an IGMP message from an attached subnet that desires the multicast

  3. Web Portal for Multicast Delivery Management.

    ERIC Educational Resources Information Center

    Mannaert, H.; De Gruyter, B.; Adriaenssens, P.

    2003-01-01

    Presents a Web portal for multicast communication management, which provides fully automatic service management with integrated provisioning of hardware equipment. Describes the software architecture, the implementation, and the application usage of the Web portal for multicast delivery. (Author/AEF)

  4. Multisites Coordination in Shared Multicast Trees

    DTIC Science & Technology

    1999-01-01

    Management Protocol ( IGMP ) allows a host to join a multicast group by informing its local router to forward multicast trac for this group to the leaf... IGMP targets group mem- bership, and multicasting routing protocols are concerned with delivery, no protocols exist to tackle an emerging problem of

  5. Wavelength multicasting in silicon photonic nanowires.

    PubMed

    Biberman, Aleksandr; Lee, Benjamin G; Turner-Foster, Amy C; Foster, Mark A; Lipson, Michal; Gaeta, Alexander L; Bergman, Keren

    2010-08-16

    We demonstrate a scalable, energy-efficient, and pragmatic method for high-bandwidth wavelength multicasting using FWM in silicon photonic nanowires. We experimentally validate up to a sixteen-way multicast of 40-Gb/s NRZ data using spectral and temporal responses, and evaluate the resulting data integrity degradation using BER measurements and power penalty performance metrics. We further examine the impact of this wavelength multicasting scalability on conversion efficiency. Finally, we experimentally evaluate up to a three-way multicast of 160-Gb/s pulsed-RZ data using spectral and temporal responses, representing the first on-chip wavelength multicasting of pulsed-RZ data.

  6. Multicast Routing of Hierarchical Data

    NASA Technical Reports Server (NTRS)

    Shacham, Nachum

    1992-01-01

    The issue of multicast of broadband, real-time data in a heterogeneous environment, in which the data recipients differ in their reception abilities, is considered. Traditional multicast schemes, which are designed to deliver all the source data to all recipients, offer limited performance in such an environment, since they must either force the source to overcompress its signal or restrict the destination population to those who can receive the full signal. We present an approach for resolving this issue by combining hierarchical source coding techniques, which allow recipients to trade off reception bandwidth for signal quality, and sophisticated routing algorithms that deliver to each destination the maximum possible signal quality. The field of hierarchical coding is briefly surveyed and new multicast routing algorithms are presented. The algorithms are compared in terms of network utilization efficiency, lengths of paths, and the required mechanisms for forwarding packets on the resulting paths.

  7. Architecture of multicast centralized key management scheme using quantum key distribution and classical symmetric encryption

    NASA Astrophysics Data System (ADS)

    Metwaly, A. F.; Rashad, M. Z.; Omara, F. A.; Megahed, A. A.

    2014-06-01

    Multicasting refers to the transmission of a message or information from one sender to multiple receivers simultaneously. Although encryption algorithms can be used to secure transmitted messages among group members, still there are many security aspects for designing a secured multicast cryptosystem. The most important aspects of Multicasting are key generation and management. The researchers have proposed several approaches for solving problems of multicast key distribution and management. In this paper, a secure key generation and distribution solution has been proposed for a single host sending to two or more (N) receivers using centralized Quantum Multicast Key Distribution Centre "QMKDC" and classical symmetric encryption. The proposed scheme uses symmetric classical algorithms for encryption and decryption transmitted messages among multicast group members, but the generated keys which are used for authentication, encryption and decryption also play an important role for designing a secured multicast cryptosystem come from QKD protocols. Authentication verified using EPR entangled Photons and controlled-NOT gate. Multiple requests for initialization as well for transmitting sensitive information handled through priority and sensitivity levels. Multiple members' communication is achieved with full or partial support of QMKDC.

  8. A Solution for Irregular IP Multicast Packet Flooding — For Heavy Traffic IP Multicast Communication

    NASA Astrophysics Data System (ADS)

    Misumi, Makoto; Nakagawa, Shin-Ichi; Chinen, Ken-Ichi; Shinoda, Yoichi; Yamaoka, Katsunori

    When an IP Multicast network is constructed on a switch-based network, many IP Multicast packet broadcasts are generated, and these broadcasts cause trouble for all of the other kinds of communication. To solve this problem, implementing IGMP Snooping on various switches has been proposed. However, some switches have insufficient IP Multicast packet-handling capability. This problem is also mentioned in RFC4541. In this paper, we propose the IGMP Snooping Activator (ISA) mechanism as a way to solve the IP Multicast packet-handling problem. The ISA transmits dummy IGMP Queries to maintain the IP Multicast network, and it joins the flooding IP Multicast group to activate IGMP Snooping in switches that are unable to handle IP Multicast packets. The experimental evaluation shows the effectiveness of our proposed method: the network load decreases because of the method's effective restraint of IP Multicast packet flooding.

  9. Efficient congestion control scheme for providing QoS to I-VPN

    NASA Astrophysics Data System (ADS)

    De Marco, Martino; Trabucchi, Sara

    1998-12-01

    In this paper we outline an overall network architecture for the Internet Service Providers who want offer an Internet- Virtual Private Network service with QoS guarantees and, at the same time, with a high-level of efficiency in the network resource usage. The proposed approach is based on the negotiation of a service level agreement, which includes the definition of profile of traffic the user is allowed to emit. The ingress nodes perform an adaptive shaping of the user traffic entering the network, driven by a fast congestion notification scheme. In this scenario, the adoption of a service architecture based on a class-of- service concept enables the Internet Service Provider to offer different level of network performance according to the customer needs.

  10. Issues in providing a reliable multicast facility

    NASA Technical Reports Server (NTRS)

    Dempsey, Bert J.; Strayer, W. Timothy; Weaver, Alfred C.

    1990-01-01

    Issues involved in point-to-multipoint communication are presented and the literature for proposed solutions and approaches surveyed. Particular attention is focused on the ideas and implementations that align with the requirements of the environment of interest. The attributes of multicast receiver groups that might lead to useful classifications, what the functionality of a management scheme should be, and how the group management module can be implemented are examined. The services that multicasting facilities can offer are presented, followed by mechanisms within the communications protocol that implements these services. The metrics of interest when evaluating a reliable multicast facility are identified and applied to four transport layer protocols that incorporate reliable multicast.

  11. Network connectivity enhancement by exploiting all optical multicast in semiconductor ring laser

    NASA Astrophysics Data System (ADS)

    Siraj, M.; Memon, M. I.; Shoaib, M.; Alshebeili, S.

    2015-03-01

    The use of smart phone and tablet applications will provide the troops for executing, controlling and analyzing sophisticated operations with the commanders providing crucial documents directly to troops wherever and whenever needed. Wireless mesh networks (WMNs) is a cutting edge networking technology which is capable of supporting Joint Tactical radio System (JTRS).WMNs are capable of providing the much needed bandwidth for applications like hand held radios and communication for airborne and ground vehicles. Routing management tasks can be efficiently handled through WMNs through a central command control center. As the spectrum space is congested, cognitive radios are a much welcome technology that will provide much needed bandwidth. They can self-configure themselves, can adapt themselves to the user requirement, provide dynamic spectrum access for minimizing interference and also deliver optimal power output. Sometimes in the indoor environment, there are poor signal issues and reduced coverage. In this paper, a solution utilizing (CR WMNs) over optical network is presented by creating nanocells (PCs) inside the indoor environment. The phenomenon of four-wave mixing (FWM) is exploited to generate all-optical multicast using semiconductor ring laser (SRL). As a result same signal is transmitted at different wavelengths. Every PC is assigned a unique wavelength. By using CR technology in conjunction with PC will not only solve network coverage issue but will provide a good bandwidth to the secondary users.

  12. Digital Multicasting of Multiple Audio Streams

    NASA Technical Reports Server (NTRS)

    Macha, Mitchell; Bullock, John

    2007-01-01

    The Mission Control Center Voice Over Internet Protocol (MCC VOIP) system (see figure) comprises hardware and software that effect simultaneous, nearly real-time transmission of as many as 14 different audio streams to authorized listeners via the MCC intranet and/or the Internet. The original version of the MCC VOIP system was conceived to enable flight-support personnel located in offices outside a spacecraft mission control center to monitor audio loops within the mission control center. Different versions of the MCC VOIP system could be used for a variety of public and commercial purposes - for example, to enable members of the general public to monitor one or more NASA audio streams through their home computers, to enable air-traffic supervisors to monitor communication between airline pilots and air-traffic controllers in training, and to monitor conferences among brokers in a stock exchange. At the transmitting end, the audio-distribution process begins with feeding the audio signals to analog-to-digital converters. The resulting digital streams are sent through the MCC intranet, using a user datagram protocol (UDP), to a server that converts them to encrypted data packets. The encrypted data packets are then routed to the personal computers of authorized users by use of multicasting techniques. The total data-processing load on the portion of the system upstream of and including the encryption server is the total load imposed by all of the audio streams being encoded, regardless of the number of the listeners or the number of streams being monitored concurrently by the listeners. The personal computer of a user authorized to listen is equipped with special- purpose MCC audio-player software. When the user launches the program, the user is prompted to provide identification and a password. In one of two access- control provisions, the program is hard-coded to validate the user s identity and password against a list maintained on a domain-controller computer

  13. Employing Multicast in P2P Overlay Networks

    NASA Astrophysics Data System (ADS)

    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.

  14. MTP: An atomic multicast transport protocol

    NASA Technical Reports Server (NTRS)

    Freier, Alan O.; Marzullo, Keith

    1990-01-01

    Multicast transport protocol (MTP); a reliable transport protocol that utilizes the multicast strategy of applicable lower layer network architectures is described. In addition to transporting data reliably and efficiently, MTP provides the client synchronization necessary for agreement on the receipt of data and the joining of the group of communicants.

  15. Privacy-Sensitive Congestion Charging

    NASA Astrophysics Data System (ADS)

    Beresford, Alastair R.; Davies, Jonathan J.; Harle, Robert K.

    National-scale congestion charging schemes are increasingly viewed as the most viable long-term strategy for controlling congestion and maintaining the viability of the road network. In this paper we challenge the widely held belief that enforceable and economically viable congestion charging schemes require drivers to give up their location privacy to the government. Instead we explore an alternative scheme where privately-owned cars enforce congestion charge payments by using an on-board vehicle unit containing a camera and wireless communications. Our solution prevents centralised tracking of vehicle movements but raises an important issue: should we trust our neighbours with a little personal information in preference to entrusting it all to the government?

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

    SciTech Connect

    Agarwal, Deborah A.

    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 protocols

  17. CodedStream: live media streaming with overlay coded multicast

    NASA Astrophysics Data System (ADS)

    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.

  18. Apply network coding for H.264/SVC multicasting

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Kuo, C.-C. Jay

    2008-08-01

    In a packet erasure network environment, video streaming benefits from error control in two ways to achieve graceful degradation. The first approach is application-level (or the link-level) forward error-correction (FEC) to provide erasure protection. The second error control approach is error concealment at the decoder end to compensate lost packets. A large amount of research work has been done in the above two areas. More recently, network coding (NC) techniques have been proposed for efficient data multicast over networks. It was shown in our previous work that multicast video streaming benefits from NC for its throughput improvement. An algebraic model is given to analyze the performance in this work. By exploiting the linear combination of video packets along nodes in a network and the SVC video format, the system achieves path diversity automatically and enables efficient video delivery to heterogeneous receivers in packet erasure channels. The application of network coding can protect video packets against the erasure network environment. However, the rank defficiency problem of random linear network coding makes the error concealment inefficiently. It is shown by computer simulation that the proposed NC video multicast scheme enables heterogenous receiving according to their capacity constraints. But it needs special designing to improve the video transmission performance when applying network coding.

  19. Sleeping and resting respiratory rates in dogs and cats with medically-controlled left-sided congestive heart failure.

    PubMed

    Porciello, F; Rishniw, M; Ljungvall, I; Ferasin, L; Haggstrom, J; Ohad, D G

    2016-01-01

    Sleeping and resting respiratory rates (SRR and RRR, respectively) are commonly used to monitor dogs and cats with left-sided cardiac disease and to identify animals with left-sided congestive heart failure (L-CHF). Dogs and cats with subclinical heart disease have SRRmean values <30 breaths/min. However, little is known about SRR and RRR in dogs and cats with CHF that is well controlled with medical therapy. In this study, SRR and RRR were measured by the owners of 51 dogs and 22 cats with stable, well-controlled CHF. Median canine SRRmean was 20 breaths/min (7-39 breaths/min); eight dogs were ≥25 breaths/min and one dog only was ≥30 breaths/min. Canine SRRmean was unrelated to pulmonary hypertension or diuretic dose. Median feline SRRmean was 20 breaths/min (13-31 breaths/min); four cats were ≥25 breaths/min and only one cat was ≥30 breaths/min. Feline SRRmean was unrelated to diuretic dose. SRR remained stable during collection in both species with little day-to-day variability. The median canine RRRmean was 24 breaths/min (12-44 breaths/min), 17 were ≥25 breaths/min, seven were ≥30 breaths/min, two were >40 breaths/min. Median feline RRRmean was 24 breaths/min (15-45 breaths/min); five cats had RRRmean ≥25 breaths/min; one had ≥30 breaths/min, and two had ≥40 breaths/min. These data suggest that most dogs and cats with CHF that is medically well-controlled and stable have SRRmean and RRRmean <30 breaths/min at home. Clinicians can use these data to help determine how best to control CHF in dogs and cats.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. The reliable multicast protocol application programming interface

    NASA Technical Reports Server (NTRS)

    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. WDM network and multicasting protocol strategies.

    PubMed

    Kirci, Pinar; Zaim, Abdul Halim

    2014-01-01

    Optical technology gains extensive attention and ever increasing improvement because of the huge amount of network traffic caused by the growing number of internet users and their rising demands. However, with wavelength division multiplexing (WDM), it is easier to take the advantage of optical networks and optical burst switching (OBS) and to construct WDM networks with low delay rates and better data transparency these technologies are the best choices. Furthermore, multicasting in WDM is an urgent solution for bandwidth-intensive applications. In the paper, a new multicasting protocol with OBS is proposed. The protocol depends on a leaf initiated structure. The network is composed of source, ingress switches, intermediate switches, edge switches, and client nodes. The performance of the protocol is examined with Just Enough Time (JET) and Just In Time (JIT) reservation protocols. Also, the paper involves most of the recent advances about WDM multicasting in optical networks. WDM multicasting in optical networks is given as three common subtitles: Broadcast and-select networks, wavelength-routed networks, and OBS networks. Also, in the paper, multicast routing protocols are briefly summarized and optical burst switched WDM networks are investigated with the proposed multicast schemes.

  3. Optimization of congested traffic by controlling stop-and-go waves.

    PubMed

    Tomer, Elad; Safonov, Leonid; Madar, Nilly; Havlin, Shlomo

    2002-06-01

    We propose a new optimization strategy based on inducing stop-and-go waves on the main road and controlling their wavelength. Using numerical simulations of a recent stochastic car-following model we show that this strategy yields optimization of traffic flow when implemented in systems with a localized periodic inhomogeneity, such as signalized intersections and entry ramps. The optimization process is explained by our finding of a generalized fundamental diagram (GFD) for traffic, namely a flux-density-wavelength relation. Projecting the GFD on the density-flux plane yields a two-dimensional region of stable states, qualitatively similar to that found empirically [Kerner, Phys. Rev. Lett. 81, 3797 (1998)] in synchronized traffic.

  4. High-performance multicasting schemes in optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Yuefeng; Liu, Xin; Zhang, Jie; Zhang, Min

    2009-11-01

    Current trends in communications indicate that multicasting is becoming increasingly popular and important in networking applications. Since multicasting can be supported more efficiently in optical domain by utilizing the inherent light-splitting capacity of optical devices, such as optical splitters, than by copying data in electronic domain, issues concerning running multicast sessions in the all-optical networks have received much attention in recent years. In this paper, different multicasting schemes and their performance in the Optical Packet Switched networks are investigated, including the parallel mode, serial mode, and hybrid mode multicasting schemes. Computer simulation results show that compared with the parallel-mode and serial-mode multicasting schemes, hybrid-mode multicasting scheme is the best way to deliver multicast sessions in the Optical Packet Switched networks due to its highest performance.

  5. Research on loss recovery of application layer multicast

    NASA Astrophysics Data System (ADS)

    Li, Xinfeng; Shi, Huiling; Niu, Zhenghao; Lei, Wenqing; Chen, Jin

    2014-04-01

    As an alternative of IP Multicast, ALM implements multicast functionality at the application layer instead of the IP layer, which addresses the problem of non-ubiquitous deployment of IP multicast. However, the reliability of ALM is low because dynamic hosts forward the data. This paper analyzes the error and delivery features of ALM trees, and further presents a data loss recovery solution (called HBHLR) for application layer multicast.

  6. The multidriver: A reliable multicast service using the Xpress Transfer Protocol

    NASA Technical Reports Server (NTRS)

    Dempsey, Bert J.; Fenton, John C.; Weaver, Alfred C.

    1990-01-01

    A reliable multicast facility extends traditional point-to-point virtual circuit reliability to one-to-many communication. Such services can provide more efficient use of network resources, a powerful distributed name binding capability, and reduced latency in multidestination message delivery. These benefits will be especially valuable in real-time environments where reliable multicast can enable new applications and increase the availability and the reliability of data and services. We present a unique multicast service that exploits features in the next-generation, real-time transfer layer protocol, the Xpress Transfer Protocol (XTP). In its reliable mode, the service offers error, flow, and rate-controlled multidestination delivery of arbitrary-sized messages, with provision for the coordination of reliable reverse channels. Performance measurements on a single-segment Proteon ProNET-4 4 Mbps 802.5 token ring with heterogeneous nodes are discussed.

  7. Market Mechanism for Line Congestion Clearance

    NASA Astrophysics Data System (ADS)

    Ruiz Monroy, José Joaquín; Kita, Hiroyuki; Tanaka, Eiichi; Hasegawa, Jun

    This paper proposes a mechanism for clearance of line congestion and power flow control in a deregulated market environment. The mechanism applies penalties to the bilateral transactions that cause line congestion by increasing the prices of such transactions. The market regulates itself by redefining the transactions and checking again for violations, applying penalties if necessary and repeating the process until all the demand is satisfied without causing line congestion to the system. A bilateral transaction matrix (BTM) creation algorithm developed by the authors and a DC power flow program are integrated as parts of the market mechanism proposed in this paper. The congestion is cleared by the market participants when they reschedule their transactions. This mechanism is useful to study the effects of bilateral transactions on a power system and helps the Independent System Operator (ISO) to create rules and market mechanisms for line congestion clearance and power flow control.

  8. A high performance totally ordered multicast protocol

    NASA Technical Reports Server (NTRS)

    Montgomery, Todd; Whetten, Brian; Kaplan, Simon

    1995-01-01

    This paper presents the Reliable Multicast Protocol (RMP). RMP provides a totally ordered, reliable, atomic multicast service on top of an unreliable multicast datagram service such as IP Multicasting. RMP is fully and symmetrically distributed so that no site bears un undue portion of the communication 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 QoS guarantees are selectable on a per packet basis. RMP provides many communication options, including virtual synchrony, a publisher/subscriber model of message delivery, an implicit naming service, mutually exclusive handlers for messages, and mutually exclusive locks. It has commonly been held that a large performance penalty must be paid in order to implement total ordering -- RMP discounts this. On SparcStation 10's on a 1250 KB/sec Ethernet, RMP provides totally ordered packet delivery to one destination at 842 KB/sec throughput and with 3.1 ms packet latency. The performance stays roughly constant independent of the number of destinations. For two or more destinations on a LAN, RMP provides higher throughput than any protocol that does not use multicast or broadcast.

  9. On the stability and multi-stability of a TCP/RED congestion control model with state-dependent delay and discontinuous marking function

    NASA Astrophysics Data System (ADS)

    Zhang, Shu; Xu, Jian; Chung, Kwok-wai

    2015-05-01

    Random early detection (RED) is an effective algorithm to control the Internet congestion. However, researches on RED parameters are difficult since there are state-dependent delay and discontinuous terms on the right-hand side of the model. We smooth the model by hyperbolic tangent function and reformulate it by a switch function to keep state variables positive. Numerical simulations on the original system validates the reformulated model. The multi-stability phenomenon is observed and some suggestions on the selection of RED parameters are given to enhance the global stability of the model by numerical bifurcation continuation on the reformulated model.

  10. Loss of the eukaryotic initiation factor 2α kinase general control nonderepressible 2 protects mice from pressure overload-induced congestive heart failure without affecting ventricular hypertrophy.

    PubMed

    Lu, Zhongbing; Xu, Xin; Fassett, John; Kwak, Dongmin; Liu, Xiaoyu; Hu, Xinli; Wang, Huan; Guo, Haipeng; Xu, Dachun; Yan, Shuo; McFalls, Edward O; Lu, Fei; Bache, Robert J; Chen, Yingjie

    2014-01-01

    In response to several stresses, including nutrient deprivation, general control nonderepressible 2 kinase (GCN2) attenuates mRNA translation by phosphorylating eukaryotic initiation factor 2α(Ser51). Energy starvation is known to exacerbate congestive heart failure, and eukaryotic initiation factor 2α(Ser51) phosphorylation is increased in the failing heart. However, the effect of GCN2 during the evolution of congestive heart failure has not been tested. In this study, we examined the influence of GCN2 expression in response to a cardiac stress by inducing chronic pressure overload with transverse aortic constriction in wild-type and GCN2 knockout mice. Under basal conditions, GCN2 knockout mice had normal left ventricular structure and function, but after transverse aortic constriction, they demonstrated less contractile dysfunction, less increase in lung weight, less increase in lung inflammation and vascular remodeling, and less myocardial apoptosis and fibrosis compared with wild-type mice, despite an equivalent degree of left ventricular hypertrophy. As expected, GCN2 knockout attenuated transverse aortic constriction-induced cardiac eukaryotic initiation factor 2α(Ser51) phosphorylation and preserved sarcoplasmic reticulum Ca(2+) ATPase expression compared with wild-type mice. Interestingly, the expression of the antiapoptotic protein Bcl-2 was significantly elevated in GCN2 knockout hearts, whereas in isolated neonatal cardiomyocytes, selective knockdown of GCN2 increased Bcl-2 protein expression and enhanced myocyte resistance to an apoptotic stress. Collectively, our data support the notion that GCN2 impairs the ventricular adaptation to chronic pressure overload by reducing Bcl-2 expression and increasing cardiomyocyte susceptibility to apoptotic stimuli. Our findings suggest that strategies to reduce GCN2 activity in cardiac tissue may be a novel approach to attenuate congestive heart failure development.

  11. Reliable multicasting in the Xpress Transport Protocol

    SciTech Connect

    Atwood, J.W.; Catrina, O.; Fenton, J.; Strayer, W.T.

    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.

  12. Congestion phenomena on complex networks.

    PubMed

    De Martino, Daniele; Dall'asta, Luca; Bianconi, Ginestra; Marsili, Matteo

    2009-01-01

    We define a minimal model of traffic flows in complex networks in order to study the trade-off between topological-based and traffic-based routing strategies. The resulting collective behavior is obtained analytically for an ensemble of uncorrelated networks and summarized in a rich phase diagram presenting second-order as well as first-order phase transitions between a free-flow phase and a congested phase. We find that traffic control improves global performance, enlarging the free-flow region in parameter space only in heterogeneous networks. Traffic control introduces nonlinear effects and, beyond a critical strength, may trigger the appearance of a congested phase in a discontinuous manner. The model also reproduces the crossover in the scaling of traffic fluctuations empirically observed on the Internet.

  13. Sympathetic reflex control of skeletal muscle blood flow in patients with congestive heart failure: evidence for beta-adrenergic circulatory control

    SciTech Connect

    Kassis, E.; Jacobsen, T.N.; Mogensen, F.; Amtorp, O.

    1986-11-01

    Mechanisms controlling forearm muscle vascular resistance (FMVR) during postural changes were investigated in seven patients with severe congestive heart failure (CHF) and in seven control subjects with unimpaired left ventricular function. Relative brachioradial muscle blood flow was determined by the local /sup 133/Xe-washout technique. Unloading of baroreceptors with use of 45 degree upright tilt was comparably obtained in the patients with CHF and control subjects. Control subjects had substantially increased FMVR and heart rate to maintain arterial pressure whereas patients with CHF had decreased FMVR by 51 +/- 11% and had no increase in heart rate despite a fall in arterial pressure during upright tilt. The autoregulatory and local vasoconstrictor reflex responsiveness during postural changes in forearm vascular pressures were intact in both groups. In the patients with CHF, the left axillary nerve plexus was blocked by local anesthesia. No alterations in forearm vascular pressures were observed. This blockade preserved the local regulation of FMVR but reversed the vasodilator response to upright tilt as FMVR increased by 30 +/- 7% (p less than .02). Blockade of central neural impulses to this limb combined with brachial arterial infusions of phentolamine completely abolished the humoral vasoconstriction in the tilted position. Infusions of propranolol to the contralateral brachial artery that did not affect baseline values of heart rate, arterial pressure, or the local reflex regulation of FMVR reversed the abnormal vasodilator response to upright tilt as FMVR increased by 42 +/- 12% (p less than .02). Despite augmented baseline values, forearm venous but not arterial plasma levels of epinephrine increased in the tilted position, as did arteri rather than venous plasma concentrations of norepinephrine in these patients.

  14. Experimental demonstration of EON node supporting reconfigurable optical superchannel multicasting.

    PubMed

    Zhu, Paikun; Li, Juhao; Chen, Yuanxiang; Chen, Xin; Wu, Zhongying; Ge, Dawei; Chen, Zhangyuan; He, Yongqi

    2015-08-10

    Elastic optical networks (EON) based on optical superchannel enables higher spectral flexibility, in which the network nodes should provide multiple all-optical functionalities to manipulate bandwidth-variable data traffic. In this paper, we propose and demonstrate an EON node structure supporting reconfigurable optical superchannel multicasting. The node structure incorporates a shared multicasting module, which performs reconfigurable selection of target incoming/outgoing superchannels/replicas and leverages a group of nonlinear devices to satisfy multiple multicast requests. Moreover, an optical comb is utilized to efficiently provide and manage all pump resources for multicasting with potential cost reduction and phase noise inhibition. Based on the node structure, we experimentally demonstrate polarization division multiplexing (PDM) superchannel multicasting scenarios with different replica amount, input/output locations, and modulation formats. Less than 0.7 dB optical signal-to-noise ratio (OSNR) penalties are demonstrated in multiple multicasting scenarios.

  15. Pathophysiology of nasal congestion

    PubMed Central

    Naclerio, Robert M; Bachert, Claus; Baraniuk, James N

    2010-01-01

    Nasal congestion is a common symptom in rhinitis (both allergic and nonallergic), rhinosinusitis and nasal polyposis. Congestion can also be caused by physical obstruction of nasal passages and/or modulation of sensory perception. Mucosal inflammation underlies many of the specific and interrelated factors that contribute to nasal congestion, as well as other symptoms of both allergic rhinitis and rhinosinusitis. A wide range of biologically active agents (eg, histamine, tumor necrosis factor-α, interleukins, cell adhesion molecules) and cell types contribute to inflammation, which can manifest as venous engorgement, increased nasal secretions and tissue swelling/edema, ultimately leading to impaired airflow and the sensation of nasal congestion. Inflammation-induced changes in the properties of sensory afferents (eg, expression of peptides and receptors) that innervate the nose can also contribute to altered sensory perception, which may result in a subjective feeling of congestion. Increased understanding of the mechanisms underlying inflammation can facilitate improved treatment selection and the development of new therapies for congestion. PMID:20463823

  16. Living on the Edge of Stagnant Water: An Assessment of Environmental Impacts of Construction-Phase Drainage Congestion Along Dhaka City Flood Control Embankment, Bangladesh

    NASA Astrophysics Data System (ADS)

    Rasid, Harun; Mallsk, Azim U.

    1996-01-01

    Environmental impacts of the construction-phase drainage congestion along the Dhaka City Flood Control Embankment were assessed by a pilot questionnaire survey (in 1991) among the target population adjacent to the embankment. The results of the survey indicated that, despite significant alleviation of river flooding, the majority of the respondents experienced a new type of flood problem in the form of stagnant water inside the embankment, immediately following its construction. Not only had this stagnant water flooded and damaged their property, it had exposed them to a number of other environmental problems, such as accumulation of municipal sewage, foul odors, mosquitoes, and growth of water hyacinth. The study found that the respondents’ assessments of these environmental problems differed significantly according to the magnitude of the impact of stagnant water upon two subgroups within the target population. A postsurvey follow-up in 1994 indicated that this problem of drainage congestion had largely been alleviated by completing the construction of a number of drainage regulators. The study concludes by stressing the importance of synchronizing the construction of drainage structures with that of the embankment systems and by underlining policy implications for flood-vulnerable land use adjacent to embankments.

  17. Lightweight causal and atomic group multicast

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.; Schiper, Andre; Stephenson, Pat

    1991-01-01

    The ISIS toolkit is a distributed programming environment based on support for virtually synchronous process groups and group communication. A suite of protocols is presented to support this model. The approach revolves around a multicast primitive, called CBCAST, which implements a fault-tolerant, causally ordered message delivery. This primitive can be used directly or extended into a totally ordered multicast primitive, called ABCAST. It normally delivers messages immediately upon reception, and imposes a space overhead proportional to the size of the groups to which the sender belongs, usually a small number. It is concluded that process groups and group communication can achieve performance and scaling comparable to that of a raw message transport layer. This finding contradicts the widespread concern that this style of distributed computing may be unacceptably costly.

  18. Fault recovery in the reliable multicast protocol

    NASA Technical Reports Server (NTRS)

    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.

  19. Multicast Communication with Guaranteed Quality of Service

    DTIC Science & Technology

    1993-12-16

    that everyone wants the multicast unless the router determines, via IGMP , that no members exist down a given path. Messages were constrained in their...area. Once a receiver is connected to the RP, it can learn who the sources are via an IGMP -Register message. Once this is known, the receiver can elect...reconfigure if necessary, by an IGMP -ESL message. This technique then provides a means by which a source specific shortest path tree can be formed without

  20. Reliable multicast protocol specifications protocol operations

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    This appendix contains the complete state tables for Reliable Multicast Protocol (RMP) Normal Operation, Multi-RPC Extensions, Membership Change Extensions, and Reformation Extensions. First the event types are presented. Afterwards, each RMP operation state, normal and extended, is presented individually and its events shown. Events in the RMP specification are one of several things: (1) arriving packets, (2) expired alarms, (3) user events, (4) exceptional conditions.

  1. Evaluation Study of a Broadband Multicasting Service over a Gigabit Ethernet Delivery Network

    NASA Astrophysics Data System (ADS)

    Stergiou, E.; Meletiou, G.; Vasiliadis, D. C.; Rizos, G. E.; Margariti, S. V.

    2008-11-01

    Multicasting networks are usually implemented for delivering audio and video. Consequently, the performance evaluation of a reliable multicasting architecture is useful in active delivery systems. In this paper we analyze and present a broadband multicasting system under an Internet environment using a typical IP multicasting mechanism. The test-bed multicasting scheme was based on both IGMP and MCOP protocols, where a Gigabit Ethernet was used as delivery network at client's segment. The evaluation study provides measurements for the two most significant performance metrics, the required Bandwidth and the Round Trip Time (RTT) of a packet versus the number of multicasting clients over 2.4 Mbps multicasting service rate.

  2. Multicast Services of QoS-Aware Active Queue Management over IP Multimedia Applications

    NASA Astrophysics Data System (ADS)

    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.

  3. Enhancing Application Layer Multicast Solutions by Wireless Underlay Support

    NASA Astrophysics Data System (ADS)

    Hübsch, Christian; Waldhorst, Oliver P.

    Application Layer Multicast (ALM) is an attractive solution to overcome the deployment problems of IP-Multicast. We show how to cope with the challenges of incorporating wireless devices into ALM protocols. As a first approach we extend the NICE protocol, significantly increasing its performance in scenarios with many devices connected through wireless LAN.

  4. Making the Traffic Operations Case for Congestion Pricing: Operational Impacts of Congestion Pricing

    SciTech Connect

    Chin, Shih-Miao; Hu, Patricia S; Davidson, Diane

    2011-02-01

    Congestion begins when an excess of vehicles on a segment of roadway at a given time, resulting in speeds that are significantly slower than normal or 'free flow' speeds. Congestion often means stop-and-go traffic. The transition occurs when vehicle density (the number of vehicles per mile in a lane) exceeds a critical level. Once traffic enters a state of congestion, recovery or time to return to a free-flow state is lengthy; and during the recovery process, delay continues to accumulate. The breakdown in speed and flow greatly impedes the efficient operation of the freeway system, resulting in economic, mobility, environmental and safety problems. Freeways are designed to function as access-controlled highways characterized by uninterrupted traffic flow so references to freeway performance relate primarily to the quality of traffic flow or traffic conditions as experienced by users of the freeway. The maximum flow or capacity of a freeway segment is reached while traffic is moving freely. As a result, freeways are most productive when they carry capacity flows at 60 mph, whereas lower speeds impose freeway delay, resulting in bottlenecks. Bottlenecks may be caused by physical disruptions, such as a reduced number of lanes, a change in grade, or an on-ramp with a short merge lane. This type of bottleneck occurs on a predictable or 'recurrent' basis at the same time of day and same day of week. Recurrent congestion totals 45% of congestion and is primarily from bottlenecks (40%) as well as inadequate signal timing (5%). Nonrecurring bottlenecks result from crashes, work zone disruptions, adverse weather conditions, and special events that create surges in demand and that account for over 55% of experienced congestion. Figure 1.1 shows that nonrecurring congestion is composed of traffic incidents (25%), severe weather (15%), work zones, (10%), and special events (5%). Between 1995 and 2005, the average percentage change in increased peak traveler delay, based on

  5. Demonstration of optical multicasting using Kerr frequency comb lines.

    PubMed

    Bao, Changjing; Liao, Peicheng; Kordts, Arne; Karpov, Maxim; Pfeiffer, Martin H P; Zhang, Lin; Yan, Yan; Xie, Guodong; Cao, Yinwen; Almaiman, Ahmed; Ziyadi, Morteza; Li, Long; Zhao, Zhe; Mohajerin-Ariaei, Amirhossein; Wilkinson, Steven R; Tur, Moshe; Fejer, Martin M; Kippenberg, Tobias J; Willner, Alan E

    2016-08-15

    We experimentally demonstrate optical multicasting using Kerr frequency combs generated from a Si3N4 microresonator. We obtain Kerr combs in two states with different noise properties by varying the pump wavelength in the resonator and investigate the effect of Kerr combs on multicasting. Seven-fold multicasting of 20 Gbaud quadrature phase-shift-keyed signals and four-fold multicasting of 16-quadrature amplitude modulation signals have been achieved when low-phase-noise combs are input into a periodically poled lithium niobate waveguide. In addition, we find that the wavelength conversion efficiency in the PPLN waveguide for chaotic combs with high noise is similar to that for low-noise combs, while the signal quality of the multicast copy is significantly degraded.

  6. Resilient peer-to-peer multicast without the cost

    NASA Astrophysics Data System (ADS)

    Birrer, Stefan; Bustamante, Fabian E.

    2004-12-01

    We introduce Nemo, a novel peer-to-peer multicast protocol that achieves high delivery ratio without sacrificing end-to-end latency or incurring additional costs. Based on two simple techniques: (1) co-leaders to minimize dependencies and, (2) triggered negative acknowledgments (NACKs) to detect lost packets, Nemo's design emphasizes conceptual simplicity and minimum dependencies, thus achieving performance characteristics capable of withstanding the natural instability of its target environment. We present an extensive comparative evaluation of our protocol through simulation and wide-area experimentation. We contrast the scalability and performance of Nemo with that of three alternative protocols: Narada, Nice and Nice-PRM. Our results show that Nemo can achieve delivery ratios similar to those of comparable protocols under high failure rates, but at a fraction of their cost in terms of duplicate packets (reductions > 90%) and control-related traffic.

  7. Resilient peer-to-peer multicast without the cost

    NASA Astrophysics Data System (ADS)

    Birrer, Stefan; Bustamante, Fabian E.

    2005-01-01

    We introduce Nemo, a novel peer-to-peer multicast protocol that achieves high delivery ratio without sacrificing end-to-end latency or incurring additional costs. Based on two simple techniques: (1) co-leaders to minimize dependencies and, (2) triggered negative acknowledgments (NACKs) to detect lost packets, Nemo's design emphasizes conceptual simplicity and minimum dependencies, thus achieving performance characteristics capable of withstanding the natural instability of its target environment. We present an extensive comparative evaluation of our protocol through simulation and wide-area experimentation. We contrast the scalability and performance of Nemo with that of three alternative protocols: Narada, Nice and Nice-PRM. Our results show that Nemo can achieve delivery ratios similar to those of comparable protocols under high failure rates, but at a fraction of their cost in terms of duplicate packets (reductions > 90%) and control-related traffic.

  8. Never Been KIST: Tor’s Congestion Management Blossoms with Kernel-Informed Socket Transport

    DTIC Science & Technology

    2014-08-01

    CUBIC congestion control algorithm. Shadow Topology Enhancements: To ensure that we are causing the most realistic performance and con- gestion effects...selection [13, 59, 60], client throttling [14, 38, 45], circuit scheduling [57], and flow/congestion control [15]. While some of this work has or will be...congestion local to relays running in the public Tor network, and use them to measure congestion from three live relays under our control . Second, we

  9. Mobile Multicast in Hierarchical Proxy Mobile IPV6

    NASA Astrophysics Data System (ADS)

    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.

  10. KHIP - A Scalable Protocol for Secure Multicast Routing

    DTIC Science & Technology

    1999-01-01

    communication between hosts and routers. Today, hosts communicate with their designated multicast router using IGMP . For secure multicast, a secure...version of IGMP needs to be developed [3]. A host could then authenticate with its router using the same four way authentication mechanism described...members and to distribute en- 3Internet Group Management Protocol ( IGMP ) [10] is the protocol that a hosts uses to communicate with an attached router

  11. Custodial Multicast in Delay Tolerant Networks: Challenges and Approaches

    DTIC Science & Technology

    2006-01-01

    Custodial Multicast in Delay Tolerant Networks Challenges and Approaches Susan Symington, Robert C. Durst , and Keith Scott The MITRE Corporation...McLean, Virginia susan@mitre.org, durst @mitre.org, kscott@mitre.org Abstract— Although custodial transmission of multicast bundles would be...Specification", draft-irtf- dtnrg-bundle-spec-05.txt , July 2005. [3] Symington, S., Durst , R., and Scott, K., “Delay-Tolerant Networking Custodial

  12. Multicast Services over Structured P2P Networks

    NASA Astrophysics Data System (ADS)

    Manzanares-Lopez, Pilar; Malgosa-Sanahuja, Josemaria; Muñoz-Gea, Juan Pedro; Sanchez-Aarnoutse, Juan Carlos

    IP multicast functionality was defined as an efficient method to transmit datagrams to a group of receivers. However, although a lot of research work has been done in this technology, IP multicast has not spread out over the Internet as much as expected, reducing its use for local environments (i.e., LANs). The peer-to-peer networks paradigm can be used to overcome the IP multicast limitations. In this new scenario (called Application Layer Multicast or ALM), the multicast functionality is changed from network to application layer. Although ALM solution can be classified into unstructured and structured solutions, the last ones are the best option to offer multicast services due to the effectiveness in the discovery nodes, their mathematical definition and the totally decentralized management. In this chapter we are going to offer a tutorial of the main structured ALM solutions, but introducing two novelties with respect to related surveys in the past: first, the systematic description of most representative structured ALM solution in OverSim (one of the most popular p2p simulation frameworks). Second, some simulation comparatives between flooding-based and tree-based structured ALM solution are also presented.

  13. Simple hierarchical approach to intra/interdomain multicasting

    NASA Astrophysics Data System (ADS)

    Chen, Shiwen; Karvelas, Dennis; Ma, Qicheng; Yener, Buelent

    1997-10-01

    In this paper, a simple hierarchical approach to inter/intra domain multicasting is introduced. The proposed Hierarchical Tree Multicast Protocol (HTMP) supports sender initiated multicasting, i.e., requires by an application starting a multicast session to provide an initial list of potential receivers. Based on this information, HTMP utilizes the unicast routing information which is currently available in the Internet routers and builds a hierarchical shared tree architecture which consists of separate intra-domain core based trees interconnected by a core based inter-domain tree that may span the entire Internet. Although HTMP requires an initial group of potential receivers, it allows for new hosts to join in supporting three modes of session participation: (a) a restricted mode which allows access only to a specified list of group members, (b) a semi- restricted mode which allows new members to join in but only after authorization from the session manager, (c) an open mode which does not require any authorization. HTMP supports a distribution (one-to-many) mode of multicasting, in which the hierarchical tree is transformed into a source based tree with core the session initiator, as well as an interactive mode (many-to-many) of multicasting. Finally, HTMP provides a receiver oriented resource reservation mechanism which allows for heterogeneity of traffic streams.

  14. Experimental characterization of a new multicasting node architecture based on space splitters and wavelength converters

    NASA Astrophysics Data System (ADS)

    He, Hao; Su, Yikai; Hu, Peigang; Hu, Weisheng

    2005-11-01

    IPTV-based broadband services such as interactive multimedia and video conferencing are considered as promising revenue-adding services, and multicast is proven to be a good supplier to support these applications for its reduced consumption of network bandwidth. Generally there are two approaches to implement optical layer multicast. One is space-domain multicast using space-splitter which is low cost but has wavelength continuity constraint, the other is frequency-domain multicast using wavelength converter which resolves the wavelength continuity but with high costs. A new multicasting node which adopts both space-domain multicast and frequency-domain multicast is recently discussed. In this paper we present an experimental demonstration of the new multicasting node architecture based on space splitters and wavelength converters, measurements to characterize such a node are provided.

  15. Simultaneous transmission of three services in a WDM-PON with wireless access for multicast data

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Wu, Yanzhi; Hu, Xiaofeng; Wang, Tao; Cao, Pan; Su, Yikai

    2010-12-01

    We propose and experimentally demonstrate a WDM-PON architecture supporting point-to-point, broadcast, and multicast services based on hybrid modulation format. Wireless access for multicast data is provided using optical carrier suppression (OCS) technology.

  16. Mobility based multicast routing in wireless mesh networks

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  19. Influence of periodic traffic congestion on epidemic spreading

    NASA Astrophysics Data System (ADS)

    Zheng, Muhua; Ruan, Zhongyuan; Tang, Ming; Do, Younghae; Liu, Zonghua

    2016-11-01

    In the metropolis, traffic congestion has become a very serious problem, especially in rush hours. This congestion causes people to have more chance to contact each other and thus will accelerate epidemic spreading. To explain this observation, we present a reaction-diffusion (RD) model with a periodic varying diffusion rate to represent the daily traveling behaviors of human beings and its influence to epidemic spreading. By extensive numerical simulations, we find that the epidemic spreading can be significantly influenced by traffic congestion where the amplitude, period and duration of diffusion rate are the three key parameters. Furthermore, a brief theory is presented to explain the effects of the three key parameters. These findings suggest that except the normal ways of controlling contagion in working places and long-distance traveling, controlling the contagion in daily traffic congestion may be another effective way to reduce epidemic spreading.

  20. The Verification-based Analysis of Reliable Multicast Protocol

    NASA Technical Reports Server (NTRS)

    Wu, Yunqing

    1996-01-01

    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 paper, we develop formal models for R.W using existing automatic verification systems, and perform verification-based analysis on the formal RMP specifications. We also use the formal models of RW specifications to generate a test suite for conformance testing of the RMP implementation. Throughout the process of RMP development, we follow an iterative, interactive approach that emphasizes concurrent and parallel progress between the 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. Initial results of the CD-1 reliable multicast experiment

    SciTech Connect

    Agarwal, D.; Stead, R.; Coan, B.; Burns, J. E.; Shah, N.; Kyriakopoulos, N.

    2000-09-29

    During the past year, an experiment has been underway to test use of reliable multicast capabilities for transmission of continuous data in the Global Communication Infrastructure. For the experiment a version of the CD-1 protocol was multicast enabled. The experiment has demonstrated the feasibility of transmitting data in a multicast mode over the GCI. In the case of the Comprehensive Nuclear Test-Ban Treaty the sender could be the station and the receivers the International Data Center (IDC) and one or more National Data Centers (NDC). The potential advantages of multicasting include (a) the timely receipt of the data by the IDC and the host NDC and (b) the simultaneous availability of the raw station data at, at least, two locations. The latter, by introducing redundant data paths, decreases the probability of loss of station data due to a potential failure of a single data receiver. This experiment is only one element of a needed more thorough assessment of the reliability and cost-effectiveness of introducing redundancies in the data transmission paths and the data sinks of the IMS. The next stage of the multicast experiment planned is installation of the multicast-enabled CD-1 software at the GERES IMS station, at the German NDC and at the IDC for further experiments with actual IMS station data. This stage of the experiment is waiting on installation of a GCI link to the German NDC. Negotiations regarding price for this installation have been on going between the Global Communication Infrastructure (GCI) contractor and the German NDC with no resolution. Current development of the CD-x protocol is proceeding in two complementary directions. Along with the work on a multicast enabled version of CD-1 there is also work to develop CD-1.1, which will add end-to-end reliability to the CD-1 protocol among other things. A possible future activity would be to combine the reliable multicast and the end-to-end reliability mechanisms into one CD-x protocol version.

  2. Consideration of Receiver Interest for IP Multicast Delivery

    DTIC Science & Technology

    2000-01-01

    A. Setup Overhead Based on current IETF standards, a common IP multicast ar- chitecture includes IGMP , PIM-SM, and MSDP; in the future a combination...of MAAA, IGMP , PIM-SM, and BGMP will be more common. Alternatives to PIM include MOSPF and DVMRP. Setting up new multicast groups in IP requires a...num- ber of steps. First, a class-D address is chosen randomly by the source. Next, hosts join the group by using IGMP to signal their local router. The

  3. Optimization of multicast optical networks with genetic algorithm

    NASA Astrophysics Data System (ADS)

    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.

  4. Auctionable fixed transmission rights for congestion management

    NASA Astrophysics Data System (ADS)

    Alomoush, Muwaffaq Irsheid

    Electric power deregulation has proposed a major change to the regulated utility monopoly. The change manifests the main part of engineers' efforts to reshape three components of today's regulated monopoly: generation, distribution and transmission. In this open access deregulated power market, transmission network plays a major role, and transmission congestion is a major problem that requires further consideration especially when inter-zonal/intra-zonal scheme is implemented. Declaring that engineering studies and experience are the criteria to define zonal boundaries or defining a zone based on the fact that a zone is a densely interconnected area (lake) and paths connecting these densely interconnected areas are inter-zonal lines will render insufficient and fuzzy definitions. Moreover, a congestion problem formulation should take into consideration interactions between intra-zonal and inter-zonal flows and their effects on power systems. In this thesis, we introduce a procedure for minimizing the number of adjustments of preferred schedules to alleviate congestion and apply control schemes to minimize interactions between zones. In addition, we give the zone definition a certain criterion based on the Locational Marginal Price (LMP). This concept will be used to define congestion zonal boundaries and to decide whether any zone should be merged with another zone or split into new zones. The thesis presents a unified scheme that combines zonal and FTR schemes to manage congestion. This combined scheme is utilized with LMPs to define zonal boundaries more appropriately. The presented scheme gains the best features of the FTR scheme, which are providing financial certainty, maximizing the efficient use of the system and making users pay for the actual use of congested paths. LMPs may give an indication of the impact of wheeling transactions, and calculations of and comparisons of LMPs with and without wheeling transactions should be adequate criteria to approve

  5. Application of Epidemiology Model on Complex Networks in Propagation Dynamics of Airspace Congestion.

    PubMed

    Dai, Xiaoxu; Hu, Minghua; Tian, Wen; Xie, Daoyi; Hu, Bin

    2016-01-01

    This paper presents a propagation dynamics model for congestion propagation in complex networks of airspace. It investigates the application of an epidemiology model to complex networks by comparing the similarities and differences between congestion propagation and epidemic transmission. The model developed satisfies the constraints of actual motion in airspace, based on the epidemiology model. Exploiting the constraint that the evolution of congestion cluster in the airspace is always dynamic and heterogeneous, the SIR epidemiology model (one of the classical models in epidemic spreading) with logistic increase is applied to congestion propagation and shown to be more accurate in predicting the evolution of congestion peak than the model based on probability, which is common to predict the congestion propagation. Results from sample data show that the model not only predicts accurately the value and time of congestion peak, but also describes accurately the characteristics of congestion propagation. Then, a numerical study is performed in which it is demonstrated that the structure of the networks have different effects on congestion propagation in airspace. It is shown that in regions with severe congestion, the adjustment of dissipation rate is more significant than propagation rate in controlling the propagation of congestion.

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

    PubMed Central

    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. PMID:26562152

  7. Congestion Pricing for Aircraft Pushback Slot Allocation.

    PubMed

    Liu, Lihua; Zhang, Yaping; Liu, Lan; Xing, Zhiwei

    2017-01-01

    In order to optimize aircraft pushback management during rush hour, aircraft pushback slot allocation based on congestion pricing is explored while considering monetary compensation based on the quality of the surface operations. First, the concept of the "external cost of surface congestion" is proposed, and a quantitative study on the external cost is performed. Then, an aircraft pushback slot allocation model for minimizing the total surface cost is established. An improved discrete differential evolution algorithm is also designed. Finally, a simulation is performed on Xinzheng International Airport using the proposed model. By comparing the pushback slot control strategy based on congestion pricing with other strategies, the advantages of the proposed model and algorithm are highlighted. In addition to reducing delays and optimizing the delay distribution, the model and algorithm are better suited for use for actual aircraft pushback management during rush hour. Further, it is also observed they do not result in significant increases in the surface cost. These results confirm the effectiveness and suitability of the proposed model and algorithm.

  8. Dynamic multicast routing scheme in WDM optical network

    NASA Astrophysics Data System (ADS)

    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.

  9. An efficient mechanism for dynamic survivable multicast traffic grooming

    NASA Astrophysics Data System (ADS)

    Yu, Xiaojun; Xiao, Gaoxi; Cheng, Tee Hiang

    2015-06-01

    Recent advances in wavelength division multiplexing (WDM) networks have helped enhance the popularity of multicasting services. However, as a single network failure may disrupt the information transmission to multiple end-users, protecting multicast requests against network failures becomes an important issue in network operation. This paper investigates the sub-wavelength level protection for dynamic multicast traffic grooming. A new method named lightpath-fragmentation based segment shared protection (LF-SSP) scheme is proposed. By carefully splitting primary/backup lightpaths into segments to improve resource sharing for both traffic grooming and protection, LF-SSP aims to minimize the network resources allocated for request protection. Extensive simulations are carried out to compare the performance of LF-SSP to some existing approaches, on sub-wavelength-level as well as wavelength-level multicast protections in different cases. Results show that LF-SSP steadily outperforms these existing methods as long as the network resources are not too limited. Influences of the add/drop port resources and the average number of destinations per connection request on the LF-SSP performance are also evaluated.

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

    NASA Technical Reports Server (NTRS)

    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.

  11. WDM Multicast Tree Construction Algorithms and Their Comparative Evaluations

    NASA Astrophysics Data System (ADS)

    Makabe, Tsutomu; Mikoshi, Taiju; Takenaka, Toyofumi

    We propose novel tree construction algorithms for multicast communication in photonic networks. Since multicast communications consume many more link resources than unicast communications, effective algorithms for route selection and wavelength assignment are required. We propose a novel tree construction algorithm, called the Weighted Steiner Tree (WST) algorithm and a variation of the WST algorithm, called the Composite Weighted Steiner Tree (CWST) algorithm. Because these algorithms are based on the Steiner Tree algorithm, link resources among source and destination pairs tend to be commonly used and link utilization ratios are improved. Because of this, these algorithms can accept many more multicast requests than other multicast tree construction algorithms based on the Dijkstra algorithm. However, under certain delay constraints, the blocking characteristics of the proposed Weighted Steiner Tree algorithm deteriorate since some light paths between source and destinations use many hops and cannot satisfy the delay constraint. In order to adapt the approach to the delay-sensitive environments, we have devised the Composite Weighted Steiner Tree algorithm comprising the Weighted Steiner Tree algorithm and the Dijkstra algorithm for use in a delay constrained environment such as an IPTV application. In this paper, we also give the results of simulation experiments which demonstrate the superiority of the proposed Composite Weighted Steiner Tree algorithm compared with the Distributed Minimum Hop Tree (DMHT) algorithm, from the viewpoint of the light-tree request blocking.

  12. All-optical non-conjugated wavelength multicasting of QPSK signal with capability of phase regeneration.

    PubMed

    Lian, Junzi; Fu, Songnian; Meng, Yan; Tang, Ming; Shum, Perry; Liu, Deming

    2014-09-22

    We propose all-optical one-to-three non-conjugated wavelength multicasting of QPSK signal with capability of phase regeneration, using dual-conjugated-pump phase sensitive amplification (PSA). Based on the seven-wave model, we can obtain phase transfer functions of individual multicasting channel. Different from two multicasting copies, the phase regeneration performance of input signal is determined by the nonlinear phase shift. Moreover, the optimal squeezing points of three multicasting channels have a deviation. Thus, there exists a regeneration performance trade-off among three multicasting channels. Our numerical simulation shows that the error vector magnitude (EVM) of 50 Gb/s QPSK signal can be successfully improved when both nonlinear phase shift and four-state position in its constellation are optimized. The calculated BER curves verify that the OSNR penalties of three multicasting channels are improved by around 1dB at BER = 10(-3).

  13. High-Performance, Reliable Multicasting: Foundations for Future Internet Groupware Applications

    NASA Technical Reports Server (NTRS)

    Callahan, John; Montgomery, Todd; Whetten, Brian

    1997-01-01

    Network protocols that provide efficient, reliable, and totally-ordered message delivery to large numbers of users will be needed to support many future Internet applications. The Reliable Multicast Protocol (RMP) is implemented on top of IP multicast to facilitate reliable transfer of data for replicated databases and groupware applications that will emerge on the Internet over the next decade. This paper explores some of the basic questions and applications of reliable multicasting in the context of the development and analysis of RMP.

  14. A Performance Comparison of On-Demand Multicast Routing Protocols for Ad Hoc Networks

    DTIC Science & Technology

    2004-12-15

    33–44, October 2001. [10] L. Ji and M. S. Corson . A Lightweight Adaptive Multicast Algorithm. In Proceedings of IEEE GLOBECOM ’98, pages 1036–1042...December 1998. [11] L. Ji and M. S. Corson . Differential Destination Multicast (DDM) Specification. Internet- Draft, draft-ietf-manet-ddm-00.txt, July... Elizabeth M. Royer and Charles E. Perkins. Multicast Operation of the Ad-hoc On- Demand Distance Vector Routing Protocol. In Proceedings of the Fifth

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Multicasting based optical inverse multiplexing in elastic optical network.

    PubMed

    Guo, Bingli; Xu, Yingying; Zhu, Paikun; Zhong, Yucheng; Chen, Yuanxiang; Li, Juhao; Chen, Zhangyuan; He, Yongqi

    2014-06-16

    Optical multicasting based inverse multiplexing (IM) is introduced in spectrum allocation of elastic optical network to resolve the spectrum fragmentation problem, where superchannels could be split and fit into several discrete spectrum blocks in the intermediate node. We experimentally demonstrate it with a 1-to-7 optical superchannel multicasting module and selecting/coupling components. Also, simulation results show that, comparing with several emerging spectrum defragmentation solutions (e.g., spectrum conversion, split spectrum), IM could reduce blocking performance significantly but without adding too much system complexity as split spectrum. On the other hand, service fairness for traffic with different granularity of these schemes is investigated for the first time and it shows that IM performs better than spectrum conversion and almost as well as split spectrum, especially for smaller size traffic under light traffic intensity.

  17. Organizing Multicast Receivers Deterministically by Packet-Loss Correlation

    DTIC Science & Technology

    1998-01-01

    source with either negative acknowledgments ( Nacks ) requesting lost data and the retransmissions that ensue during packet-loss, or positive...any receiver to respond to a Nack , and the Reliable Multicast Transport Protocol (RMTP) [17] appoints \\designated receivers", or- ganized into a tree... Nacks , and retransmissions, which reduces the load on the source and the network. The question is how to establish such an organized local recovery

  18. Ordered End-to-End Multicast for Distributed Multimedia Systems

    DTIC Science & Technology

    2006-01-01

    Ordering of messages compensates for the lack of a global system state and the effects of asynchrony, unpredictable network delay, and disparities in...separate logical propagation graph or global clock synchronization, and ordering is dis- tributed across nodes on the delivery paths between sources...set on route by PN, deciding on a globally valid num- ber, and multicasting the message to the receiver set with a final and binding sequence number

  19. CONGESTIVE HEART FAILURE ASSOCIATED WITH PREGNANCY IN OKAPI (OKAPIA JOHNSTONI).

    PubMed

    Warren, Joshua D; Aitken-Palmer, Copper; Weldon, Alan D; Flanagan, Joseph P; Howard, Lauren L; Garner, Michael M; Citino, Scott B

    2017-03-01

    Acute signs associated with cardiovascular disease occurred in three pregnant okapi ( Okapia johnstoni ) during early to midgestation and progressed to congestive heart failure. Congestive heart failure was diagnosed antemortem using echocardiography and plasma cardiac troponin levels. Clinical signs included decreased activity, hyporexia, tachypnea, dyspnea, flared nostrils, and productive coughing with copious amounts of foamy nasal discharge. Parenteral and oral treatment with furosemide, enalapril, and spironolactone controlled clinical signs in the three okapi allowing each to carry out one pregnancy to term. Two okapi carried the first pregnancy to term after showing signs, while one okapi aborted the first calf and gave birth to a healthy calf in a subsequent pregnancy. Subsequent pregnancy in one okapi ended with abortion and associated dystocia and endometritis. Following parturition, clinical signs associated with heart failure resolved in all three individuals; serial echocardiography in two individuals showed improvement in fractional shortening and left atrial size and all three okapi showed markedly decreased pleural effusion and resolution of pulmonary edema. However, subsequent pregnancies in all three okapi induced respiratory distress and recurrence of congestive heart failure; one okapi died from congestive heart failure associated with subsequent pregnancy. This case series describes the clinical presentation and pathologic findings of congestive heart failure during pregnancy in adult okapi.

  20. Congestion Pricing for Aircraft Pushback Slot Allocation

    PubMed Central

    Zhang, Yaping

    2017-01-01

    In order to optimize aircraft pushback management during rush hour, aircraft pushback slot allocation based on congestion pricing is explored while considering monetary compensation based on the quality of the surface operations. First, the concept of the “external cost of surface congestion” is proposed, and a quantitative study on the external cost is performed. Then, an aircraft pushback slot allocation model for minimizing the total surface cost is established. An improved discrete differential evolution algorithm is also designed. Finally, a simulation is performed on Xinzheng International Airport using the proposed model. By comparing the pushback slot control strategy based on congestion pricing with other strategies, the advantages of the proposed model and algorithm are highlighted. In addition to reducing delays and optimizing the delay distribution, the model and algorithm are better suited for use for actual aircraft pushback management during rush hour. Further, it is also observed they do not result in significant increases in the surface cost. These results confirm the effectiveness and suitability of the proposed model and algorithm. PMID:28114429

  1. Noise performance of phase-insensitive frequency multicasting in parametric mixer with finite dispersion.

    PubMed

    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.

  2. Congestion and decongestion in a communication network.

    PubMed

    Singh, Brajendra K; Gupte, Neelima

    2005-05-01

    We study network traffic dynamics in a two-dimensional communication network with regular nodes and hubs. If the network experiences heavy message traffic, congestion occurs due to the finite capacity of the nodes. We discuss strategies to manipulate hub capacity and hub connections to relieve congestion and define a coefficient of betweenness centrality (CBC), a direct measure of network traffic, which is useful for identifying hubs that are most likely to cause congestion. The addition of assortative connections to hubs of high CBC relieves congestion very efficiently.

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

    PubMed Central

    Choi, Sangil; Park, Jong Hyuk

    2016-01-01

    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. PMID:27918438

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  6. Continuous ultrafiltration for congestive heart failure: the CUORE trial.

    PubMed

    Marenzi, Giancarlo; Muratori, Manuela; Cosentino, Eugenio R; Rinaldi, Elisa R; Donghi, Valeria; Milazzo, Valentina; Ferramosca, Emiliana; Borghi, Claudio; Santoro, Antonio; Agostoni, Piergiuseppe

    2014-05-01

    Background: There are limited data comparing ultrafiltration with standard medical therapy as first-line treatment in patients with severe congestive heart failure (HF). We compared ultrafiltration and conventional therapy in patients hospitalized for HF and overt fluid overload.Methods and Results: Fifty-six patients with congestive HF were randomized to receive standard medical therapy (control group; n = 29) or ultrafiltration (ultrafiltration group; = 27). The primary endpoint of the study was rehospitalizations for congestive HF during a 1-year follow-up. Despite similar body weight reduction at hospital discharge in the 2 groups (7.5 ± 4.5 and 7.9 ± 5.0 kg, respectively;P = .75), a lower incidence of rehospitalizations for HF was observed in the ultrafiltration-treated patients during the following year (hazard ratio 0.14, 95% confidence interval 0.04-0.48; P = .002).Ultrafiltration-induced benefit was associated with a more stable renal function, unchanged furosemide dose, and lower B-type natriuretic peptide levels. At 1 year, 7 deaths (30%) occurred in the ultrafiltration group and 11 (44%) in the control group (P = .33).Conclusions: In HF patients with severe fluid overload, first-line treatment with ultrafiltration is associated with a prolonged clinical stabilization and a greater freedom from rehospitalization for congestive HF.

  7. Stochastic Stability in Internet Router Congestion Games

    NASA Astrophysics Data System (ADS)

    Chung, Christine; Pyrga, Evangelia

    Congestion control at bottleneck routers on the internet is a long standing problem. Many policies have been proposed for effective ways to drop packets from the queues of these routers so that network endpoints will be inclined to share router capacity fairly and minimize the overflow of packets trying to enter the queues. We study just how effective some of these queuing policies are when each network endpoint is a self-interested player with no information about the other players’ actions or preferences. By employing the adaptive learning model of evolutionary game theory, we study policies such as Droptail, RED, and the greedy-flow-punishing policy proposed by Gao et al. [10] to find the stochastically stable states: the states of the system that will be reached in the long run.

  8. The MIM web gateway to IP multicast e-meetings

    NASA Astrophysics Data System (ADS)

    Parviainen, Roland; Parnes, Peter

    2003-12-01

    As video conferencing and e-meeting systems are used more and more on the Internet and in businesses it becomes increasingly important to be able to participate from any computer at any location. Often this is impossible, since these systems requires often special software that are not available everywhere or impossible to install for administrative reasons. Many locations also lack the necessary network infrastructure such as IP multicast. This paper presents a WWW gateway system that enables users to participate using only a standard web browser. The design and architecture of the system are described and performance tests that show the scalability of the system are also presented.

  9. Programming with process groups: Group and multicast semantics

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.; Cooper, Robert; Gleeson, Barry

    1991-01-01

    Process groups are a natural tool for distributed programming and are increasingly important in distributed computing environments. Discussed here is a new architecture that arose from an effort to simplify Isis process group semantics. The findings include a refined notion of how the clients of a group should be treated, what the properties of a multicast primitive should be when systems contain large numbers of overlapping groups, and a new construct called the causality domain. A system based on this architecture is now being implemented in collaboration with the Chorus and Mach projects.

  10. Increased walking variability in elderly persons with congestive heart failure

    NASA Technical Reports Server (NTRS)

    Hausdorff, J. M.; Forman, D. E.; Ladin, Z.; Goldberger, A. L.; Rigney, D. R.; Wei, J. Y.

    1994-01-01

    OBJECTIVES: To determine the effects of congestive heart failure on a person's ability to walk at a steady pace while ambulating at a self-determined rate. SETTING: Beth Israel Hospital, Boston, a primary and tertiary teaching hospital, and a social activity center for elderly adults living in the community. PARTICIPANTS: Eleven elderly subjects (aged 70-93 years) with well compensated congestive heart failure (NY Heart Association class I or II), seven elderly subjects (aged 70-79 years) without congestive heart failure, and 10 healthy young adult subjects (aged 20-30 years). MEASUREMENTS: Subjects walked for 8 minutes on level ground at their own selected walking rate. Footswitches were used to measure the time between steps. Step rate (steps/minute) and step rate variability were calculated for the entire walking period, for 30 seconds during the first minute of the walk, for 30 seconds during the last minute of the walk, and for the 30-second period when each subject's step rate variability was minimal. Group means and 5% and 95% confidence intervals were computed. MAIN RESULTS: All measures of walking variability were significantly increased in the elderly subjects with congestive heart failure, intermediate in the elderly controls, and lowest in the young subjects. There was no overlap between the three groups using the minimal 30-second variability (elderly CHF vs elderly controls: P < 0.001, elderly controls vs young: P < 0.001), and no overlap between elderly subjects with and without congestive heart failure when using the overall variability. For all four measures, there was no overlap in any of the confidence intervals, and all group means were significantly different (P < 0.05).

  11. 160-Gb/s optical time division multiplexing and multicasting in parametric amplifiers.

    PubMed

    Brès, Camille-Sophie; Wiberg, Andreas O J; Coles, James; Radic, Stojan

    2008-10-13

    We report the generation of an optical time division multiplexed single data channel at 160 Gb/s using a one-pump fiber-optic parametric amplifier, and its subsequent multicasting. A two-pump fiber optic parametric amplifier was used to perform all-optical multicasting of 160 Gb/s channel to four data streams. New processing scheme combined the increase in signal extinction ratio and low-impairment multicasting using continuous-wave parametric pumps. Selective conjugation of 160 Gb/s was demonstrated for the first time.

  12. 75 FR 22770 - National Electric Transmission Congestion Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... National Electric Transmission Congestion Study AGENCY: Office of Electricity Delivery and Energy Reliability (OE), Department of Energy. ACTION: Notice of Availability of 2009 National Electric Transmission... notice that it has issued a National Electric Transmission Congestion Study (2009 Congestion Study)...

  13. Verification and validation of a reliable multicast protocol

    NASA Technical Reports Server (NTRS)

    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.

  14. Multicasts for Faster Science Applications on Beowulf Clusters

    NASA Astrophysics Data System (ADS)

    Tamblyn, P.; Levison, H.; Asphaug, E.

    2002-12-01

    We describe the use of reliable multicasts in existing message passing (MPI) programs to reduce collective communication bottlenecks. By broadcasting information through one point-to-multipoint message instead of a series of (tree-structured) point-to-point TCP messages, communication delays can be reduced by factors up to log2(Nnodes), e.g., 6x for 64-node clusters. This reduction in the cost of collective communications broadens the class of problems appropriate for Beowulf-style supercomputing. We present raw communication and science application (Swift N-body integrator) speed-up results. In addition to impressive gains in scaling for some classes of existing programs, the broader benefit of these results is to reduce the importance of domain decomposition. The cost of sending a message to all nodes is the same as one node-to-node message. This allows Beowulfs to be applied effectively even to problems requiring every node to know the current state of all other nodes' particles/cells/.... This should significantly increase the range of problems approachable with relatively cheap, Ethernet-based Beowulf clusters. The reduced cost of collective communications can also make it easier to write adequate parallel programs, thereby increasing the pool of potential Beowulf programmers. Finally, we discuss as a future possibility how Internet2's ubiquitous support for multicasts and high reliability make it a promising medium for expanding these results to geographically distributed computing resources. This research is supported by NASA AISRP through grant NAG5-9320.

  15. Relationship Between Carbon Dioxide Levels and Reported Congestion and Headaches on the International Space Station

    NASA Technical Reports Server (NTRS)

    Cole, Robert; Wear, Mary; Young, Millennia; Cobel, Christopher; Mason, Sara

    2017-01-01

    Congestion is commonly reported during spaceflight, and most crewmembers have reported using medications for congestion during International Space Station (ISS) missions. Although congestion has been attributed to fluid shifts during spaceflight, fluid status reaches equilibrium during the first week after launch while congestion continues to be reported throughout long duration missions. Congestion complaints have anecdotally been reported in relation to ISS CO2 levels; this evaluation was undertaken to determine whether or not an association exists. METHODS: Reported headaches, congestion symptoms, and CO2 levels were obtained for ISS expeditions 2-31, and time-weighted means and single-point maxima were determined for 24-hour (24hr) and 7-day (7d) periods prior to each weekly private medical conference. Multiple imputation addressed missing data, and logistic regression modeled the relationship between probability of reported event of congestion or headache and CO2 levels, adjusted for possible confounding covariates. The first seven days of spaceflight were not included to control for fluid shifts. Data were evaluated to determine the concentration of CO2 required to maintain the risk of congestion below 1% to allow for direct comparison with a previously published evaluation of CO2 concentrations and headache. RESULTS: This study confirmed a previously identified significant association between CO2 and headache and also found a significant association between CO2 and congestion. For each 1-mm Hg increase in CO2, the odds of a crew member reporting congestion doubled. The average 7-day CO2 would need to be maintained below 1.5 mmHg to keep the risk of congestion below 1%. The predicted probability curves of ISS headache and congestion curves appear parallel when plotted against ppCO2 levels with congestion occurring at approximately 1mmHg lower than a headache would be reported. DISCUSSION: While the cause of congestion is multifactorial, this study showed

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Adaptive Demand-Driven Multicast Routing in Multi-Hop Wireless Ad Hoc Networks

    DTIC Science & Technology

    2004-05-06

    16] L. Ji and M. S. Corson . A Lightweight Adaptive Multicast Algorithm. In Proceedings of IEEE GLOBECOM ’98, pages 1036–1042, December 1998. [17] L...Ji and M. S. Corson . Differential Destination Multicast (DDM) Specification. Internet- Draft, draft-ietf-manet-ddm-00.txt, July 2000. Work in...3 [30] Charles E. Perkins, Elizabeth M. Royer, and Samir R. Das. Ad Hoc On Demand Distance Vector (AODV) Routing. Internet-Draft, draft-ietf-manet

  18. Development of a Real-Time Monitoring System and Integration of Different Computer System in LHD Experiments Using IP Multicast

    NASA Astrophysics Data System (ADS)

    Emoto, Masahiko; Nakamura, Yukio; Teramachi, Yasuaki; Okumura, Haruhiko; Yamaguchi, Satarou

    There are several different computer systems in LHD (Large Helical Device) experiment, and therefore the coalition of these computers is a key to perform the experiment. Real-time monitoring system is also important because the long discharge is needed in the LHD experiment. In order to achieve these two requirements, the technique of IP multicast is adopted.The authors have developed three new systems, the first one is the real-time monitoring system, the next one is the delivery system of the shot number and the last one is the real-time notification system of the plasma data registration. The first system can deliver the real-time monitoring data to the LHD experimental LAN through the firewall of the LHD control LAN in NIFS. The other two systems are used to realize high coalition of the different computers in the LHD plasma experiment. We can conclude that IP multicast is very useful both in the LHD experiment and a future large plasma experiment from various experiences.

  19. Traffic congestion in interconnected complex networks

    NASA Astrophysics Data System (ADS)

    Tan, Fei; Wu, Jiajing; Xia, Yongxiang; Tse, Chi K.

    2014-06-01

    Traffic congestion in isolated complex networks has been investigated extensively over the last decade. Coupled network models have recently been developed to facilitate further understanding of real complex systems. Analysis of traffic congestion in coupled complex networks, however, is still relatively unexplored. In this paper, we try to explore the effect of interconnections on traffic congestion in interconnected Barabási-Albert scale-free networks. We find that assortative coupling can alleviate traffic congestion more readily than disassortative and random coupling when the node processing capacity is allocated based on node usage probability. Furthermore, the optimal coupling probability can be found for assortative coupling. However, three types of coupling preferences achieve similar traffic performance if all nodes share the same processing capacity. We analyze interconnected Internet autonomous-system-level graphs of South Korea and Japan and obtain similar results. Some practical suggestions are presented to optimize such real-world interconnected networks accordingly.

  20. Understanding congested travel in urban areas.

    PubMed

    Çolak, Serdar; Lima, Antonio; González, Marta C

    2016-03-15

    Rapid urbanization and increasing demand for transportation burdens urban road infrastructures. The interplay of number of vehicles and available road capacity on their routes determines the level of congestion. Although approaches to modify demand and capacity exist, the possible limits of congestion alleviation by only modifying route choices have not been systematically studied. Here we couple the road networks of five diverse cities with the travel demand profiles in the morning peak hour obtained from billions of mobile phone traces to comprehensively analyse urban traffic. We present that a dimensionless ratio of the road supply to the travel demand explains the percentage of time lost in congestion. Finally, we examine congestion relief under a centralized routing scheme with varying levels of awareness of social good and quantify the benefits to show that moderate levels are enough to achieve significant collective travel time savings.

  1. Congestion and cascades in payment systems

    NASA Astrophysics Data System (ADS)

    Beyeler, Walter E.; Glass, Robert J.; Bech, Morten L.; Soramäki, Kimmo

    2007-10-01

    We develop a parsimonious model of the interbank payment system. The model incorporates an endogenous instruction arrival process, a scale-free topology of payments between banks, a fixed total liquidity which limits banks’ capacity to process arriving instructions, and a global market that distributes liquidity. We find that at low liquidity the system becomes congested and payment settlement loses correlation with payment instruction arrival, becoming coupled across the network. The onset of congestion is evidently related to the relative values of three characteristic times: the time for banks’ net position to return to 0, the time for a bank to exhaust its liquidity endowment, and the liquidity market relaxation time. In the congested regime settlement takes place in cascades having a characteristic length scale. A global liquidity market substantially attenuates congestion, requiring only a small fraction of the payment-induced liquidity flow to achieve strong beneficial effects.

  2. Understanding congested travel in urban areas

    NASA Astrophysics Data System (ADS)

    Çolak, Serdar; Lima, Antonio; González, Marta C.

    2016-03-01

    Rapid urbanization and increasing demand for transportation burdens urban road infrastructures. The interplay of number of vehicles and available road capacity on their routes determines the level of congestion. Although approaches to modify demand and capacity exist, the possible limits of congestion alleviation by only modifying route choices have not been systematically studied. Here we couple the road networks of five diverse cities with the travel demand profiles in the morning peak hour obtained from billions of mobile phone traces to comprehensively analyse urban traffic. We present that a dimensionless ratio of the road supply to the travel demand explains the percentage of time lost in congestion. Finally, we examine congestion relief under a centralized routing scheme with varying levels of awareness of social good and quantify the benefits to show that moderate levels are enough to achieve significant collective travel time savings.

  3. Understanding congested travel in urban areas

    PubMed Central

    Çolak, Serdar; Lima, Antonio; González, Marta C.

    2016-01-01

    Rapid urbanization and increasing demand for transportation burdens urban road infrastructures. The interplay of number of vehicles and available road capacity on their routes determines the level of congestion. Although approaches to modify demand and capacity exist, the possible limits of congestion alleviation by only modifying route choices have not been systematically studied. Here we couple the road networks of five diverse cities with the travel demand profiles in the morning peak hour obtained from billions of mobile phone traces to comprehensively analyse urban traffic. We present that a dimensionless ratio of the road supply to the travel demand explains the percentage of time lost in congestion. Finally, we examine congestion relief under a centralized routing scheme with varying levels of awareness of social good and quantify the benefits to show that moderate levels are enough to achieve significant collective travel time savings. PMID:26978719

  4. Traffic congestion in interconnected complex networks.

    PubMed

    Tan, Fei; Wu, Jiajing; Xia, Yongxiang; Tse, Chi K

    2014-06-01

    Traffic congestion in isolated complex networks has been investigated extensively over the last decade. Coupled network models have recently been developed to facilitate further understanding of real complex systems. Analysis of traffic congestion in coupled complex networks, however, is still relatively unexplored. In this paper, we try to explore the effect of interconnections on traffic congestion in interconnected Barabási-Albert scale-free networks. We find that assortative coupling can alleviate traffic congestion more readily than disassortative and random coupling when the node processing capacity is allocated based on node usage probability. Furthermore, the optimal coupling probability can be found for assortative coupling. However, three types of coupling preferences achieve similar traffic performance if all nodes share the same processing capacity. We analyze interconnected Internet autonomous-system-level graphs of South Korea and Japan and obtain similar results. Some practical suggestions are presented to optimize such real-world interconnected networks accordingly.

  5. Multicast and Bulk Lookup in Structured Overlay Networks

    NASA Astrophysics Data System (ADS)

    Ghodsi, Ali

    Structured overlay networks are often used to implement a Distributed Hash Table (DHT) abstraction. In this chapter, we argue that structured overlay networks are suitable for doing efficient group communication. We provide algorithms that enable a node to efficiently broadcast a message to all other nodes in a structured overlay network, without inducing any redundant messages. We also provide algorithms that enasble any node to efficiently send a message to all nodes in a specified set of identifiers. Such algorithms have found usage in many structured overlay networks that implement range queries. Similarly, we provide algorithms that enable any node to efficiently send a message to the nodes responsible for any of the identifiers in a specified set of identifiers. Finally, we look at a case study of implementing efficient Application Level Multicast (ALM) using the group communication algorithms on top of structured overlay networks.

  6. Focus on renal congestion in heart failure.

    PubMed

    Afsar, Baris; Ortiz, Alberto; Covic, Adrian; Solak, Yalcin; Goldsmith, David; Kanbay, Mehmet

    2016-02-01

    Hospitalizations due to heart failure are increasing steadily despite advances in medicine. Patients hospitalized for worsening heart failure have high mortality in hospital and within the months following discharge. Kidney dysfunction is associated with adverse outcomes in heart failure patients. Recent evidence suggests that both deterioration in kidney function and renal congestion are important prognostic factors in heart failure. Kidney congestion in heart failure results from low cardiac output (forward failure), tubuloglomerular feedback, increased intra-abdominal pressure or increased venous pressure. Regardless of the cause, renal congestion is associated with increased morbidity and mortality in heart failure. The impact on outcomes of renal decongestion strategies that do not compromise renal function should be explored in heart failure. These studies require novel diagnostic markers that identify early renal damage and renal congestion and allow monitoring of treatment responses in order to avoid severe worsening of renal function. In addition, there is an unmet need regarding evidence-based therapeutic management of renal congestion and worsening renal function. In the present review, we summarize the mechanisms, diagnosis, outcomes, prognostic markers and treatment options of renal congestion in heart failure.

  7. Focus on renal congestion in heart failure

    PubMed Central

    Afsar, Baris; Ortiz, Alberto; Covic, Adrian; Solak, Yalcin; Goldsmith, David; Kanbay, Mehmet

    2016-01-01

    Hospitalizations due to heart failure are increasing steadily despite advances in medicine. Patients hospitalized for worsening heart failure have high mortality in hospital and within the months following discharge. Kidney dysfunction is associated with adverse outcomes in heart failure patients. Recent evidence suggests that both deterioration in kidney function and renal congestion are important prognostic factors in heart failure. Kidney congestion in heart failure results from low cardiac output (forward failure), tubuloglomerular feedback, increased intra-abdominal pressure or increased venous pressure. Regardless of the cause, renal congestion is associated with increased morbidity and mortality in heart failure. The impact on outcomes of renal decongestion strategies that do not compromise renal function should be explored in heart failure. These studies require novel diagnostic markers that identify early renal damage and renal congestion and allow monitoring of treatment responses in order to avoid severe worsening of renal function. In addition, there is an unmet need regarding evidence-based therapeutic management of renal congestion and worsening renal function. In the present review, we summarize the mechanisms, diagnosis, outcomes, prognostic markers and treatment options of renal congestion in heart failure. PMID:26798459

  8. An improved method for network congestion control

    NASA Astrophysics Data System (ADS)

    Qiao, Xiaolin

    2013-03-01

    The rapid progress of the wireless network technology has great convenience on the people's life and work. However, because of its openness, the mobility of the terminal and the changing topology, the wireless network is more susceptible to security attacks. Authentication and key agreement is the base of the network security. The authentication and key agreement mechanism can prevent the unauthorized user from accessing the network, resist malicious network to deceive the lawful user, encrypt the session data by using the exchange key and provide the identification of the data origination. Based on characteristics of the wireless network, this paper proposed a key agreement protocol for wireless network. The authentication of protocol is based on Elliptic Curve Cryptosystems and Diffie-Hellman.

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

    PubMed Central

    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. PMID:25834838

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

    PubMed

    Kwon, Jung-Hyok; Kim, Eui-Jik

    2016-04-11

    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.

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

    PubMed Central

    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. PMID:27077859

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

    PubMed

    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.

  13. Congestion transition in air traffic networks.

    PubMed

    Monechi, Bernardo; Servedio, Vito D P; Loreto, Vittorio

    2015-01-01

    Air Transportation represents a very interesting example of a complex techno-social system whose importance has considerably grown in time and whose management requires a careful understanding of the subtle interplay between technological infrastructure and human behavior. Despite the competition with other transportation systems, a growth of air traffic is still foreseen in Europe for the next years. The increase of traffic load could bring the current Air Traffic Network above its capacity limits so that safety standards and performances might not be guaranteed anymore. Lacking the possibility of a direct investigation of this scenario, we resort to computer simulations in order to quantify the disruptive potential of an increase in traffic load. To this end we model the Air Transportation system as a complex dynamical network of flights controlled by humans who have to solve potentially dangerous conflicts by redirecting aircraft trajectories. The model is driven and validated through historical data of flight schedules in a European national airspace. While correctly reproducing actual statistics of the Air Transportation system, e.g., the distribution of delays, the model allows for theoretical predictions. Upon an increase of the traffic load injected in the system, the model predicts a transition from a phase in which all conflicts can be successfully resolved, to a phase in which many conflicts cannot be resolved anymore. We highlight how the current flight density of the Air Transportation system is well below the transition, provided that controllers make use of a special re-routing procedure. While the congestion transition displays a universal scaling behavior, its threshold depends on the conflict solving strategy adopted. Finally, the generality of the modeling scheme introduced makes it a flexible general tool to simulate and control Air Transportation systems in realistic and synthetic scenarios.

  14. Congestion Transition in Air Traffic Networks

    PubMed Central

    Monechi, Bernardo; Servedio, Vito D. P.; Loreto, Vittorio

    2015-01-01

    Air Transportation represents a very interesting example of a complex techno-social system whose importance has considerably grown in time and whose management requires a careful understanding of the subtle interplay between technological infrastructure and human behavior. Despite the competition with other transportation systems, a growth of air traffic is still foreseen in Europe for the next years. The increase of traffic load could bring the current Air Traffic Network above its capacity limits so that safety standards and performances might not be guaranteed anymore. Lacking the possibility of a direct investigation of this scenario, we resort to computer simulations in order to quantify the disruptive potential of an increase in traffic load. To this end we model the Air Transportation system as a complex dynamical network of flights controlled by humans who have to solve potentially dangerous conflicts by redirecting aircraft trajectories. The model is driven and validated through historical data of flight schedules in a European national airspace. While correctly reproducing actual statistics of the Air Transportation system, e.g., the distribution of delays, the model allows for theoretical predictions. Upon an increase of the traffic load injected in the system, the model predicts a transition from a phase in which all conflicts can be successfully resolved, to a phase in which many conflicts cannot be resolved anymore. We highlight how the current flight density of the Air Transportation system is well below the transition, provided that controllers make use of a special re-routing procedure. While the congestion transition displays a universal scaling behavior, its threshold depends on the conflict solving strategy adopted. Finally, the generality of the modeling scheme introduced makes it a flexible general tool to simulate and control Air Transportation systems in realistic and synthetic scenarios. PMID:25993476

  15. Performance of QoS-based multicast routing algorithms for real-time communication

    NASA Astrophysics Data System (ADS)

    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.

  16. Limb congestion enhances the synchronization of sympathetic outflow with muscle contraction

    NASA Technical Reports Server (NTRS)

    Mostoufi-Moab, S.; Herr, M. D.; Silber, D. H.; Gray, K. S.; Leuenberger, U. A.; Sinoway, L. I.

    2000-01-01

    In this report, we examined if the synchronization of muscle sympathetic nerve activity (MSNA) with muscle contraction is enhanced by limb congestion. To explore this relationship, we applied signal-averaging techniques to the MSNA signal obtained during short bouts of forearm contraction (2-s contraction/3-s rest cycle) at 40% maximal voluntary contraction for 5 min. We performed this analysis before and after forearm venous congestion; an intervention that augments the autonomic response to sustained static muscle contractions via a local effect on muscle afferents. There was an increased percentage of the MSNA noted during second 2 of the 5-s contraction/rest cycles. The percentage of total MSNA seen during this particular second increased from minute 1 to 5 of contraction and was increased further by limb congestion (control minute 1 = 25.6 +/- 2.0%, minute 5 = 32.8 +/- 2.2%; limb congestion minute 1 = 29.3 +/- 2.1%, minute 5 = 37.8 +/- 3.9%; exercise main effect <0.005; limb congestion main effect P = 0.054). These changes in the distribution of signal-averaged MSNA were seen despite the fact that the mean number of sympathetic discharges did not increase over baseline. We conclude that synchronization of contraction and MSNA is seen during short repetitive bouts of handgrip. The sensitizing effect of contraction time and limb congestion are apparently due to feedback from muscle afferents within the exercising muscle.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Congestive heart failure and central sleep apnea.

    PubMed

    Sands, Scott A; Owens, Robert L

    2015-07-01

    Congestive heart failure (CHF) is among the most common causes of admission to hospitals in the United States, especially in those over age 65. Few data exist regarding the prevalence CHF of Cheyne-Stokes respiration (CSR) owing to congestive heart failure in the intensive care unit (ICU). Nevertheless, CSR is expected to be highly prevalent among those with CHF. Treatment should focus on the underlying mechanisms by which CHF increases loop gain and promotes unstable breathing. Few data are available to determine prevalence of CSR in the ICU, or how CSR might affect clinical management and weaning from mechanical ventilation.

  19. Congestion Management Requirements, Methods and Performance Indices

    SciTech Connect

    Kirby, B.J.

    2002-08-28

    Transmission congestion occurs when there is insufficient transmission capacity to simultaneously accommodate all requests for transmission service within a region. Historically, vertically integrated utilities managed this condition by constraining the economic dispatch of generators with the objective of ensuring security and reliability of their own and/or neighboring systems. Electric power industry restructuring has moved generation investment and operations decisions into the competitive market but has left transmission as a communal resource in the regulated environment. This mixing of competitive generation and regulated transmission makes congestion management difficult. The difficulty is compounded by increases in the amount of congestion resulting from increased commercial transactions and the relative decline in the amount of transmission. Transmission capacity, relative to peak load, has been declining in all regions of the U.S. for over a decade. This decline is expected to continue. Congestion management schemes used today have negative impacts on energy markets, such as disruptions and monetary penalties, under some conditions. To mitigate these concerns various congestion management methods have been proposed, including redispatch and curtailment of scheduled energy transmission. In the restructured electric energy industry environment, new congestion management approaches are being developed that strive to achieve the desired degree of reliability while supporting competition in the bulk power market. This report first presents an overview and background on key issues and emerging approaches to congestion management. It goes on to identify and describe policies affecting congestion management that are favored and/or are now being considered by FERC, NERC, and one of the regional reliability councils (WSCC). It reviews the operational procedures in use or proposed by three of the leading independent system operators (ISOs) including ERCOT

  20. Rate allocation protocol using competitive pricing for improving performance of multicast sessions

    NASA Astrophysics Data System (ADS)

    Levy, Zohar; Dolev, Danny

    1998-10-01

    Rate allocation using the Max-Min fairness criterion may highly discriminate against multicast and long unicast sessions and may lead to sever network underutilization. In this paper, we present a solution for rate allocation that is based on competitive pricing. The resultant allocation increases fairness towards multicast sessions and improves network utilization considerably. The solution requires no re-routing of sessions. The economy on which we base our solution is simple enough, enabling its implementation for practical use. We present a distributed asynchronous protocol suitable for the ATM ABR service, which achieves the economy's allocation efficiently and with short convergence time.

  1. Design alternatives for process group membership and multicast

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.; Cooper, Robert; Gleeson, Barry

    1991-01-01

    Process groups are a natural tool for distributed programming, and are increasingly important in distributed computing environments. However, there is little agreement on the most appropriate semantics for process group membership and group communication. These issues are of special importance in the Isis system, a toolkit for distributed programming. Isis supports several styles of process group, and a collection of group communication protocols spanning a range of atomicity and ordering properties. This flexibility makes Isis adaptable to a variety of applications, but is also a source of complexity that limits performance. This paper reports on a new architecture that arose from an effort to simplify Isis process group semantics. Our findings include a refined notion of how the clients of a group should be treated, what the properties of a multicast primitive should be when systems contain large numbers of overlapping groups, and a new construct called the casuality domain. As an illustration, we apply the architecture to the problem of converting processes into fault-tolerant process groups in a manner that is 'transparent' to other processes in the system.

  2. The comparison of network congestion avoidance algorithms in data exchange networks.

    NASA Astrophysics Data System (ADS)

    Grzyb, S.; Orłowski, P.

    2017-01-01

    Effective congestion control strategies allow in maintaining low delay and high throughput in data exchange networks. These requirements seem to be the most desired by network environment participants. Wide range of algorithms are proposed in the literature to approximate to these ideal parameters. All of these approaches are focused on alleviating the results of sudden, unexpected network state changes. This paper discuss a comparison of four control strategies, focused on congestion avoidance. All of them are in charge of queue length control in active network nodes. For research purpose, non-stationary, discrete, dynamical model of communication channel has been used. Research results are presented in table and chart form.

  3. Managing congestive heart failure using home telehealth.

    PubMed

    Schneider, Nina M

    2004-10-01

    Congestive heart failure (CHF) is the leading cause of rehospitalization and loss of revenue for home care agencies and hospitals. This article outlines how an agency used telehealth to provide CHF patients quality care and improved outcomes while decreasing the number of skilled home nursing visits and reducing rehospitalization rates to 1.2%.

  4. Congestive Heart Failure home monitoring pilot study in urban Denver.

    PubMed

    Bakhshi, Saba; Li, Xin; Semenov, Nikolay; Apodaca-Madrid, Jesús; Mahoor, Mohammad H; Newman, Kimberly E; Long, Carlin S; Neuman, Christine

    2011-01-01

    With a growing number of low-income patients developing Congestive Heart Failure in urban Denver, accessible and affordable solutions are needed to provide home management options. A multidisciplinary team evaluated currently available options for telemonitoring and developed a solution for an initial pilot study. This system is currently used in the Denver Metro area (Colorado) for 44 CHF patients. Preliminary results show this approach is effective and has reduced the patients' average length of stay at the hospital compared to historical data and control patients who do not use a remote monitoring system.

  5. Airport Characterization for the Adaptation of Surface Congestion Management Approaches

    DTIC Science & Technology

    2013-02-01

    1 of 2 Airport Characterization for the Adaptation of Surface Congestion Management Approaches Melanie Sandberg, Tom Reynolds...TYPE 3. DATES COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE Airport Characterization for the Adaptation of Surface Congestion Management...1 Airport Characterization for the Adaptation of Surface Congestion Management Approaches* Melanie

  6. Design of On-Chip N-Fold Orbital Angular Momentum Multicasting Using V-Shaped Antenna Array

    PubMed Central

    Du, Jing; Wang, Jian

    2015-01-01

    We design a V-shaped antenna array to realize on-chip multicasting from a single Gaussian beam to four orbital angular momentum (OAM) beams. A pattern search assisted iterative (PSI) algorithm is used to design an optimized continuous phase pattern which is further discretized to generate collinearly superimposed multiple OAM beams. Replacing the designed discrete phase pattern with corresponding V-shaped antennas, on-chip N-fold OAM multicasting is achieved. The designed on-chip 4-fold OAM multicasting exploiting V-shaped antenna array shows favorable operation performance with low crosstalk less than -15 dB. PMID:25951325

  7. A minimal model for congestion phenomena on complex networks

    NASA Astrophysics Data System (ADS)

    DeMartino, Daniele; Dall'Asta, Luca; Bianconi, Ginestra; Marsili, Matteo

    2009-08-01

    We study a minimal model of traffic flows in complex networks, simple enough for getting analytical results, but with a very rich phenomenology, presenting continuous, discontinuous as well as hybrid phase transitions between a free-flow phase and a congested phase, critical points and different behaviors of scaling with the system size. It consists of random walkers on a queuing network with one-range repulsion, where particles can be destroyed only if they can move. We focus on the dependence on the topology as well as on the level of traffic control. We are able to obtain transition curves and phase diagrams at an analytical level for the ensemble of uncorrelated networks and numerically for single instances. We find that traffic control improves global performance, enlarging the free-flow region in parameter space only in heterogeneous networks. Traffic control introduces non-linear effects and, beyond a critical strength, may trigger the appearance of a congested phase in a discontinuous manner. The model also reproduces the crossover in the scaling of traffic fluctuations empirically observed in the Internet, and moreover, a conserved version can reproduce qualitatively some stylized facts of traffic in transportation networks.

  8. Analysis of Aircraft Clusters to Measure Sector-Independent Airspace Congestion

    NASA Technical Reports Server (NTRS)

    Bilimoria, Karl D.; Lee, Hilda Q.

    2005-01-01

    The Distributed Air/Ground Traffic Management (DAG-TM) concept of operations* permits appropriately equipped aircraft to conduct Free Maneuvering operations. These independent aircraft have the freedom to optimize their trajectories in real time according to user preferences; however, they also take on the responsibility to separate themselves from other aircraft while conforming to any local Traffic Flow Management (TFM) constraints imposed by the air traffic service provider (ATSP). Examples of local-TFM constraints include temporal constraints such as a required time of arrival (RTA), as well as spatial constraints such as regions of convective weather, special use airspace, and congested airspace. Under current operations, congested airspace typically refers to a sector(s) that cannot accept additional aircraft due to controller workload limitations; hence Dynamic Density (a metric that is indicative of controller workload) can be used to quantify airspace congestion. However, for Free Maneuvering operations under DAG-TM, an additional metric is needed to quantify the airspace congestion problem from the perspective of independent aircraft. Such a metric would enable the ATSP to prevent independent aircraft from entering any local areas of congestion in which the flight deck based systems and procedures may not be able to ensure separation. This new metric, called Gaggle Density, offers the ATSP a mode of control to regulate normal operations and to ensure safety and stability during rare-normal or off-normal situations (e.g., system failures). It may be difficult to certify Free Maneuvering systems for unrestricted operations, but it may be easier to certify systems and procedures for specified levels of Gaggle Density that could be monitored by the ATSP, and maintained through relatively minor flow-rate (RTA type) restrictions. Since flight deck based separation assurance is airspace independent, the challenge is to measure congestion independent of sector

  9. Energy-Efficient Algorithm for Multicasting in Duty-Cycled Sensor Networks.

    PubMed

    Chen, Quan; Cheng, Siyao; Gao, Hong; Li, Jianzhong; Cai, Zhipeng

    2015-12-11

    Multicasting is a fundamental network service for one-to-many communications in wireless sensor networks. However, when the sensor nodes work in an asynchronous duty-cycled way, the sender may need to transmit the same message several times to one group of its neighboring nodes, which complicates the minimum energy multicasting problem. Thus, in this paper, we study the problem of minimum energy multicasting with adjusted power (the MEMAP problem) in the duty-cycled sensor networks, and we prove it to be NP-hard. To solve such a problem, the concept of an auxiliary graph is proposed to integrate the scheduling problem of the transmitting power and transmitting time slot and the constructing problem of the minimum multicast tree in MEMAP, and a greedy algorithm is proposed to construct such a graph. Based on the proposed auxiliary graph, an approximate scheduling and constructing algorithm with an approximation ratio of 4 l n K is proposed, where K is the number of destination nodes. Finally, the theoretical analysis and experimental results verify the efficiency of the proposed algorithm in terms of the energy cost and transmission redundancy.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. A Self-Driven and Adaptive Adjusting Teaching Learning Method for Optimizing Optical Multicast Network Throughput

    NASA Astrophysics Data System (ADS)

    Liu, Huanlin; Xu, Yifan; Chen, Yong; Zhang, Mingjia

    2016-09-01

    With the development of one point to multiple point applications, network resources become scarcer and wavelength channels become more crowded in optical networks. To improve the bandwidth utilization, the multicast routing algorithm based on network coding can greatly increase the resource utilization, but it is most difficult to maximize the network throughput owing to ignoring the differences between the multicast receiving nodes. For making full use of the destination nodes' receives ability to maximize optical multicast's network throughput, a new optical multicast routing algorithm based on teaching-learning-based optimization (MR-iTLBO) is proposed in the paper. In order to increase the diversity of learning, a self-driven learning method is adopted in MR-iTLBO algorithm, and the mutation operator of genetic algorithm is introduced to prevent the algorithm into a local optimum. For increasing learner's learning efficiency, an adaptive learning factor is designed to adjust the learning process. Moreover, the reconfiguration scheme based on probability vector is devised to expand its global search capability in MR-iTLBO algorithm. The simulation results show that performance in terms of network throughput and convergence rate has been improved significantly with respect to the TLBO and the variant TLBO.

  12. Energy-Efficient Algorithm for Multicasting in Duty-Cycled Sensor Networks

    PubMed Central

    Chen, Quan; Cheng, Siyao; Gao, Hong; Li, Jianzhong; Cai, Zhipeng

    2015-01-01

    Multicasting is a fundamental network service for one-to-many communications in wireless sensor networks. However, when the sensor nodes work in an asynchronous duty-cycled way, the sender may need to transmit the same message several times to one group of its neighboring nodes, which complicates the minimum energy multicasting problem. Thus, in this paper, we study the problem of minimum energy multicasting with adjusted power (the MEMAP problem) in the duty-cycled sensor networks, and we prove it to be NP-hard. To solve such a problem, the concept of an auxiliary graph is proposed to integrate the scheduling problem of the transmitting power and transmitting time slot and the constructing problem of the minimum multicast tree in MEMAP, and a greedy algorithm is proposed to construct such a graph. Based on the proposed auxiliary graph, an approximate scheduling and constructing algorithm with an approximation ratio of 4lnK is proposed, where K is the number of destination nodes. Finally, the theoretical analysis and experimental results verify the efficiency of the proposed algorithm in terms of the energy cost and transmission redundancy. PMID:26690446

  13. Improving Explicit Congestion Notification with the Mark-Front Strategy

    NASA Technical Reports Server (NTRS)

    Liu, Chunlei; Jain, Raj

    2001-01-01

    Delivering congestion signals is essential to the performance of networks. Current TCP/IP networks use packet losses to signal congestion. Packet losses not only reduces TCP performance, but also adds large delay. Explicit Congestion Notification (ECN) delivers a faster indication of congestion and has better performance. However, current ECN implementations mark the packet from the tail of the queue. In this paper, we propose the mark-front strategy to send an even faster congestion signal. We show that mark-front strategy reduces buffer size requirement, improves link efficiency and provides better fairness among users. Simulation results that verify our analysis are also presented.

  14. Impact of traffic congestion on road accidents: a spatial analysis of the M25 motorway in England.

    PubMed

    Wang, Chao; Quddus, Mohammed A; Ison, Stephen G

    2009-07-01

    Traffic congestion and road accidents are two external costs of transport and the reduction of their impacts is often one of the primary objectives for transport policy makers. The relationship between traffic congestion and road accidents however is not apparent and less studied. It is speculated that there may be an inverse relationship between traffic congestion and road accidents, and as such this poses a potential dilemma for transport policy makers. This study aims to explore the impact of traffic congestion on the frequency of road accidents using a spatial analysis approach, while controlling for other relevant factors that may affect road accidents. The M25 London orbital motorway, divided into 70 segments, was chosen to conduct this study and relevant data on road accidents, traffic and road characteristics were collected. A robust technique has been developed to map M25 accidents onto its segments. Since existing studies have often used a proxy to measure the level of congestion, this study has employed a precise congestion measurement. A series of Poisson based non-spatial (such as Poisson-lognormal and Poisson-gamma) and spatial (Poisson-lognormal with conditional autoregressive priors) models have been used to account for the effects of both heterogeneity and spatial correlation. The results suggest that traffic congestion has little or no impact on the frequency of road accidents on the M25 motorway. All other relevant factors have provided results consistent with existing studies.

  15. Nitrendipine binding in congestive heart failure due to myocardial infarction

    SciTech Connect

    Dixon, I.M.; Lee, S.L.; Dhalla, N.S. )

    1990-03-01

    Depressed cardiac pump function is the hallmark of congestive heart failure, and it is suspected that decreased influx of Ca2+ into the cardiac cell is responsible for depressed contractile function. Since Ca2+ channels in the sarcolemmal membrane are considered to be an important route for the entry of Ca2+, we examined the status of Ca2+ receptors/channels in failing rat hearts after myocardial infarction of the left ventricular free wall. For this purpose, the left coronary artery was ligated and hearts were examined 4, 8, and 16 weeks later; sham-operated animals served as controls. Hemodynamic assessment revealed decreased total mechanical energy (left ventricular systolic pressure x heart rate), increased left ventricular diastolic pressure, and decreased positive and negative dP/dt in experimental animals at 4, 8, and 16 weeks. Although accumulation of ascites in the abdominal cavity was evident at 4 weeks, other clinical signs of congestive heart failure in experimental rats were evident from the presence of lung congestion and cardiac dilatation at 8 and 16 weeks after induction of myocardial infarction. The density of Ca2+ receptors/channels in crude membranes, as assessed by (3H)nitrendipine binding assay, was found to be decreased in the uninfarcted experimental left ventricle at 8 and 16 weeks; however, no change in the affinity of nitrendipine was evident. A similar depression in the specific binding of another dihydropyridine compound, (3H)PN200-110, was also evident in failing hearts. Brain and skeletal muscle crude membrane preparations, unlike those of the right ventricle and liver, revealed a decrease in Ca2+ receptors/channels density in experimental animals at 16 weeks.

  16. Abdominal contributions to cardiorenal dysfunction in congestive heart failure.

    PubMed

    Verbrugge, Frederik H; Dupont, Matthias; Steels, Paul; Grieten, Lars; Malbrain, Manu; Tang, W H Wilson; Mullens, Wilfried

    2013-08-06

    Current pathophysiological models of congestive heart failure unsatisfactorily explain the detrimental link between congestion and cardiorenal function. Abdominal congestion (i.e., splanchnic venous and interstitial congestion) manifests in a substantial number of patients with advanced congestive heart failure, yet is poorly defined. Compromised capacitance function of the splanchnic vasculature and deficient abdominal lymph flow resulting in interstitial edema might both be implied in the occurrence of increased cardiac filling pressures and renal dysfunction. Indeed, increased intra-abdominal pressure, as an extreme marker of abdominal congestion, is correlated with renal dysfunction in advanced congestive heart failure. Intriguing findings provide preliminary evidence that alterations in the liver and spleen contribute to systemic congestion in heart failure. Finally, gut-derived hormones might influence sodium homeostasis, whereas entrance of bowel toxins into the circulatory system, as a result of impaired intestinal barrier function secondary to congestion, might further depress cardiac as well as renal function. Those toxins are mainly produced by micro-organisms in the gut lumen, with presumably important alterations in advanced heart failure, especially when renal function is depressed. Therefore, in this state-of-the-art review, we explore the crosstalk between the abdomen, heart, and kidneys in congestive heart failure. This might offer new diagnostic opportunities as well as treatment strategies to achieve decongestion in heart failure, especially when abdominal congestion is present. Among those currently under investigation are paracentesis, ultrafiltration, peritoneal dialysis, oral sodium binders, vasodilator therapy, renal sympathetic denervation and agents targeting the gut microbiota.

  17. Current Management of Congestive Heart Failure

    PubMed Central

    Lopez, J.F.

    1989-01-01

    Congestive heart failure is still one of the most common causes of death in our society. Treatment should be approached systematically with a set of well-defined objectives, which include rest, a low-sodium diet, inotropic agents, diuretics, and peripheral vasodilators. Patients receiving treatment for congestive heart failure should be examined daily for symptomatic improvement, cardiac signs, and accurate recording of total fluid intake and output. Serum electrolyte levels and chest X-ray films should also be checked intermittently. When using powerful diuretics or vasodilators, the physician should be aware of the risk-benefit ratio because many of these drugs, alone or in combination, may produce undesirable or even fatal side-effects. PMID:20469506

  18. Can complexity decrease in congestive heart failure?

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sayan; Palit, Sanjay Kumar; Banerjee, Santo; Ariffin, M. R. K.; Rondoni, Lamberto; Bhattacharya, D. K.

    2015-12-01

    The complexity of a signal can be measured by the Recurrence period density entropy (RPDE) from the reconstructed phase space. We have chosen a window based RPDE method for the classification of signals, as RPDE is an average entropic measure of the whole phase space. We have observed the changes in the complexity in cardiac signals of normal healthy person (NHP) and congestive heart failure patients (CHFP). The results show that the cardiac dynamics of a healthy subject is more complex and random compare to the same for a heart failure patient, whose dynamics is more deterministic. We have constructed a general threshold to distinguish the border line between a healthy and a congestive heart failure dynamics. The results may be useful for wide range for physiological and biomedical analysis.

  19. [Current echography diagnosis of pelvic congestion syndrome].

    PubMed

    Malinova, M; Shopov, A

    2012-01-01

    Chronic pelvic pain is a common condition. The sources of pelvic pain are multifactorial, and their causes are difficult to determine. Pelvic congestion syndrome (PCS) is associated with varicose ovarian veins and/or varicose veins in the pelvis. The syndrome is associated with constant dull pelvic pain, abnormal menstrual bleeding, tenderness to touch in lower abdomen, pain during intercourse, painful menstrual periods, vaginal discharge, PCOS. The specific diagnosis of Pelvic Congestion Syndrome is made using several tests which include ultrasound, CAT, MIR, MDCT (multidetector) and venogram. The ultrasound is the first test of choice. It can assess the uterus and other organs in the pelvis. Doppler ultrasound can also help visualize the blood flow and asses the presence of varicosities in the pelvis.

  20. Nonlinear dynamics of congestive heart failure (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Bernjak, Alan; Clarkson, Peter B. M.; McClintock, Peter V. E.; Stefanovska, Aneta

    2005-05-01

    Preliminary results are reported from a research project analysing congestive heart failure in terms a stochastic coupled-oscillator model of the cardiovascular system. Measurements of blood flow by laser Doppler flowmetry (LDF) have been processed by use of the wavelet transform to separate its oscillatory components, which number at least five. Particular attention was concentrated on the frequency content near 0.01 Hz, which is known to be associated with endothelial function. The LDF was carried out in conjunction with iontophoretically administered acetylcholine (ACh) and sodium nitroprusside (SNP) in order to evaluate endothelial reactivity. Measurements were made on 17 congestive heart failure (CHF) patients (a) on first diagnosis, and (b) again several weeks later after their treatment with a β-blocker had been stabilised. The results of these two sets of measurements are being compared with each other, and with data from an age and sex-matched group of healthy controls. It is confirmed that endothelial reactivity is reduced in CHF patients, as compared to healthy controls, and it is found that one effect of the Beta-blocker is to ameliorate the loss of endothelial function in CHF. The implications of these results are discussed.

  1. Cascading Failures in Congested Scale-Free Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jian-Feng; Yang, Ling-Xiao; Gao, Zi-You; Fu, Bai-Bai

    In this work, we study the effect of congestion on the behavior of cascading failures in scale-free networks, where a capacity is assigned on each node (controlled by a tolerance parameter α), and traffic flows are governed by user equilibrium instead of going along the shortest paths. The effect of congestion can be described by link cost function, which denotes the time needed to travel along the link. Here we focus on studying the effect of link's practical capacity, which is a parameter in link cost function. Two different kinds of link's practical capacity are investigated, i.e. uniform case and nonuniform case. In the uniform case, each link has the same value of practical capacity. While in the nonuniform case, we assume that link's practical capacity and degrees of the link's endpoints are correlated (controlled by parameter θ, which governs the heterogeneity of link's practical capacity). Simulation results show that, in the uniform case, scale-free networks are more prone to cascading failures when increasing the value of link's practical capacity. In the nonuniform case, cascading failures in scale-free networks are very sensitive to α when θ > 0; while θ < 0, scale-free networks may suffer from serious cascading failures, regardless of α.

  2. Cardiac CT Angiography in Congestive Heart Failure.

    PubMed

    Levine, Avi; Hecht, Harvey S

    2015-06-01

    Cardiac CT angiography has become an important tool for the diagnosis and treatment of congestive heart failure. Differentiation of ischemic from nonischemic cardiomyopathy; evaluation of myocardial perfusion; characterization of hypertrophic cardiomyopathy, left ventricular noncompaction, and arrhythmogenic right ventricular dysplasia; and delineation of congenital heart defects and valvular abnormalities are the primary diagnostic applications. Therapeutic use includes visualization of the coronary venous anatomy for optimal implementation of cardiac resynchronization therapy and evaluation of left ventricular assist devices and transplant vasculopathy.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Onset of traffic congestion in complex networks.

    PubMed

    Zhao, Liang; Lai, Ying-Cheng; Park, Kwangho; Ye, Nong

    2005-02-01

    Free traffic flow on a complex network is key to its normal and efficient functioning. Recent works indicate that many realistic networks possess connecting topologies with a scale-free feature: the probability distribution of the number of links at nodes, or the degree distribution, contains a power-law component. A natural question is then how the topology influences the dynamics of traffic flow on a complex network. Here we present two models to address this question, taking into account the network topology, the information-generating rate, and the information-processing capacity of individual nodes. For each model, we study four kinds of networks: scale-free, random, and regular networks and Cayley trees. In the first model, the capacity of packet delivery of each node is proportional to its number of links, while in the second model, it is proportional to the number of shortest paths passing through the node. We find, in both models, that there is a critical rate of information generation, below which the network traffic is free but above which traffic congestion occurs. Theoretical estimates are given for the critical point. For the first model, scale-free networks and random networks are found to be more tolerant to congestion. For the second model, the congestion condition is independent of network size and topology, suggesting that this model may be practically useful for designing communication protocols.

  5. [Parallel pharmacological correction of myocardial dysfunction, cognitive and psychopathological disordres in patients with congestive heart failure].

    PubMed

    Dotsenko, N Ia; Boev, S S; Shekhunova, I A; Dedova, V O

    2014-01-01

    Was examined 92 patients with congestive heart failure III-IV FC with fraction of emission left ventricle < 45% against coronary artery disease. Patients of control group received basic therapy (according to recommendations of the Ukrainian society of cardiology), the 1 group--in addition received a preparation of Vazonat within 15 days intravenously in a dose of 1000 mg a day further are out-patient within 1 month on 250 mg 3 times per os; the 2 group--under the same scheme a preparation of Vazonat and a day tranquilizer of Adapto in a dose of 500 mg twice a day throughout all term of supervision. It is established that addition of Vazonat to basic treatment leads to additional effect concerning improvement of indicators cardio-hemodynamic, to improvement congestive functions. Joint appointment of preparations of Vazonat and Adaptol against basic treatment leads to more expressed improvement congestive functions, to progressive reduction of degree of trouble, depression.

  6. Optimal weighting scheme for suppressing cascades and traffic congestion in complex networks.

    PubMed

    Yang, Rui; Wang, Wen-Xu; Lai, Ying-Cheng; Chen, Guanrong

    2009-02-01

    This paper is motivated by the following two related problems in complex networks: (i) control of cascading failures and (ii) mitigation of traffic congestion. Both problems are of significant recent interest as they address, respectively, the security of and efficient information transmission on complex networks. Taking into account typical features of load distribution and weights in real-world networks, we have discovered an optimal solution to both problems. In particular, we shall provide numerical evidence and theoretical analysis that, by choosing a proper weighting parameter, a maximum level of robustness against cascades and traffic congestion can be achieved, which practically rids the network of occurrences of the catastrophic dynamics.

  7. Elephantiasis Nostras Verrucosa (ENV): a complication of congestive heart failure and obesity.

    PubMed

    Baird, Drew; Bode, David; Akers, Troy; Deyoung, Zachariah

    2010-01-01

    Congestive heart failure (CHF) and obesity are common medical conditions that have many complications and an increasing incidence in the United States. Presented here is a case of a disfiguring skin condition that visually highlights the dermatologic consequences of poorly controlled CHF and obesity. This condition will probably become more common as CHF and obesity increase in the US.

  8. Congestion Measures for Organized Markets in the U.S.

    SciTech Connect

    Fisher, Emily; Eto, Joseph H.

    2013-12-16

    Transmission lines deliver electricity that is generated at power plants to loads. When there is not sufficient transmission capacity to schedule or transport all desired electricity transfers, the transmission system is constrained, and the particular line, flowgate or interface is congested. While it is useful to measure congestion for several reasons—to identify where and how much congestion exists and how this changes over time, to determine whether or what to do about it, and to assess the effectiveness of actions taken—it is challenging to measure congestion in a meaningful and consistent way across markets or over time in the same market. This paper examines current public reporting of congestion measures for organized markets in the U.S., and what these measures can and cannot tell us about congestion across regions or over time in the same region.

  9. Advanced Congestive Heart Failure Associated With Disseminated Intravascular Coagulopathy.

    PubMed

    Sarcon, Annahita; Liu, Xiaoli; Ton, David; Haywood, James; Hitchcock, Todd

    2015-01-01

    Background. Disseminated intravascular coagulopathy (DIC) is a complication of an underlying disease and not a primary illness. It is most commonly associated with sepsis, trauma, obstetrical complications, and malignancies. There are very few cases in the literature illustrating the association between DIC and congestive heart failure. Findings. In this report, we present a case of severe congestive heart failure, leading to biventricular thrombi and subsequently DIC. Conclusion. We suggest that the association between congestive heart failure and DIC is an underrecognized one. Congestive heart failure continues to remain a major cause of morbidity and mortality despite advances in medical therapies. Thus far, the precise role of coagulation factors in congestive heart failure is unknown. Further investigations are needed to elucidate the pathophysiology of congestive heart failure and coagulation factors.

  10. Advanced practice nursing for congestive heart failure.

    PubMed

    McCormick, S A

    1999-02-01

    Congestive heart failure (CHF) is an enormous burden on society and the health care system. The role of the advanced practice nurse (APN) in CHF is multifaceted and combines inpatient, outpatient, and community patient care skills. Case management and quality management have been traditional focuses, with a high level of practice impact on patient care. Outcomes management in the APN role for CHF care is the future for measurable outcomes and maximum impact on organizational values. Because outcomes management is an evolving field for the APN, focus on a chronic disease such as CHF is a very valuable tool for implementation.

  11. Prehospital management of congestive heart failure.

    PubMed

    Mattu, Amal; Lawner, Benjamin

    2009-01-01

    The evolution of prehospital treatment of decompensated congestive heart failure has in some ways come full circle: rather than emphasizing a battery of new pharmacotherapies, out-of-hospital providers have a renewed focus on aggressive use of nitrates, optimization of airway support, and rapid transport. The use of furosemide and morphine has become de-emphasized, and a flurry of research activity and excitement revolves around the use of noninvasive positive-pressure ventilation. Further research will clarify the role of bronchodilators and angiotensin-converting enzyme inhibitors in the prehospital setting.

  12. Traffic Congestion Model: Challenges and Opportunities

    NASA Astrophysics Data System (ADS)

    Enjat Munajat, M. D.; Munir, Rinaldi; Widyantoro, Dwi H.

    2017-01-01

    This paper discusses models to detect traffic congestion using two approaches: road detection and moving object detection. There are two methods proposed to detect roads and moving objects. The methods involve the detection of both moving and non-moving objects. The system presented in this paper is able to detect roads as well as moving objects. However, further development is needed to detect extreme road curves. The system presented in this paper is relatively inexpensive since it only uses one camera and capable of capturing satisfactorily detailed images.

  13. Modeling congestion on urban roads and assessing level of service

    SciTech Connect

    Maitra, B.; Sikdar, P.K.; Dhingra, S.L.

    1999-12-01

    A unified methodology has been proposed for the quantification of congestion, incorporating the volume and operational characteristics of traffic movement. The level of congestion has been modeled to relate to the causal influences of traffic movement. Modeling congestion has provided a quantitative basis for understanding the contribution of different vehicle types in overall congestion, and it is useful for evolving the policy for congestion mitigation. Quantified congestion level has been used as a logical and improved measure of effectiveness to account for the conceptual definition of level of service in a quantitative manner. Based on the congestion level, 10 levels of service have been proposed, with 9 in stable flow zone (presently designated as A-E), and 1 representing an unstable operation (presently designated as F). The philosophy has been demonstrated by developing congestion models and assessing the effect of roadway width on congestion levels and service volumes. While it is possible to assess the realized benefits from an increase in roadway width, the required number of traffic lanes for a desired level of service can also be estimated.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. MQUAKE multicast software early warning demonstrated for 31 October 2001 Anza Ml5.1 earthquake

    NASA Astrophysics Data System (ADS)

    Eakins, J. A.; Hansen, T.; Vernon, F. L.; Braun, H.

    2003-12-01

    MQUAKE distributes real-time multicast parametric information from individual sensors as well as a summarized location and magnitude based on the data recorded from sensors of the ANZA seismic network with the goal of providing event notification prior to arrival of the actual shock wave at the client's location. The program gathers detection and triggering information from an operational Antelope real-time data collection system and sends them to clients via multicast and unicast UDP packets. Multicast packets are preferred as they allow multiple people to receive event packets in the fastest time possible (however, a unicast mode is available since most IP networks do not support multicast). These packets are decrypted in a client software which then produces a list of triggers/events that will be used in future versions of the code to generate wavefront estimate plots and approximate maximum shock wave travel times based on the client's location and limited current information. This systems works in both a wired and wireless environment, such as HPWREN, the High Performance Wireless Research and Education Network. A real-time example of this system was obtained during the Ml5.1 31 October 2001 earthquake that occurred directly under the ANZA seismic network, approximately 70 km away from an MQUAKE client. The MQUAKE program was able to deliver a warning of a significant "event" 10 seconds after the initial ground motion was recorded and about 4 seconds prior to ground motion reaching the client. An actual event location and magnitude approximation was received 71 seconds after the local ground shaking at the client's location (85 seconds after the event). Had the client been located along the coast of San Diego, they would have had additional warning time prior to the shaking. Clients in San Diego, the closest major metropolitan area to this event, could have received up to 12 seconds of early warning.

  17. Performance Analysis of Protocol Independent Multicasting-Dense Mode in Low Earth Orbit Satellite Networks

    DTIC Science & Technology

    2003-03-01

    2-18 2.6.1 Internet Gateway Management Protocol ( IGMP )......................................... 2-21 2.6.2 Distance Vector...large-scale deployment, leading to the present hierarchical approaches of today. 2.6.1 Internet Gateway Management Protocol ( IGMP ) IGMP provides...address space under IPv4, and under the multicast address range (0xFF in the highest octet) of IPv6. Group membership is managed via IGMP through

  18. Optimal multicasting in a multi-line-rate ethernet-over-WDM network

    NASA Astrophysics Data System (ADS)

    Harve, Shruthi; Batayneh, Marwan; Mukherjee, Biswanath

    2009-11-01

    Ethernet is the dominant transport technology for Local Area Networks. Efforts are now under way to use carrier-grade Ethernet in backbone networks of different service providers. With the advent of applications such as IPTV and Videoon- Demand, there is need for techniques to route multicast traffic over the Ethernet backbone networks. Here, we address the problem of Routing and Wavelength Assignment (RWA) of a set of multicast requests in a Multi-Line-Rate Ethernet backbone network with the objective of minimizing the cost of setting up the network, in terms of the Service Provider's Capital Expenditure (CAPEX). We present an Auxiliary Graph based heuristic algorithm that routes each multicast request on a light-tree structure, and assigns minimum cost wavelengths along the route. We compare the properties of the algorithm to the optimal solution given by a mathematical model formulated as an Integer Linear Program (ILP), and show that they compare very well. We also find that the algorithm is most cost-effective when the incoming requests are processed in descending order of their bandwidth requirements.

  19. Proxy-assisted multicasting of video streams over mobile wireless networks

    NASA Astrophysics Data System (ADS)

    Nguyen, Maggie; Pezeshkmehr, Layla; Moh, Melody

    2005-03-01

    This work addresses the challenge of providing seamless multimedia services to mobile users by proposing a proxy-assisted multicast architecture for delivery of video streams. We propose a hybrid system of streaming proxies, interconnected by an application-layer multicast tree, where each proxy acts as a cluster head to stream out content to its stationary and mobile users. The architecture is based on our previously proposed Enhanced-NICE protocol, which uses an application-layer multicast tree to deliver layered video streams to multiple heterogeneous receivers. We targeted the study on placements of streaming proxies to enable efficient delivery of live and on-demand video, supporting both stationary and mobile users. The simulation results are evaluated and compared with two other baseline scenarios: one with a centralized proxy system serving the entire population and one with mini-proxies each to serve its local users. The simulations are implemented using the J-SIM simulator. The results show that even though proxies in the hybrid scenario experienced a slightly longer delay, they had the lowest drop rate of video content. This finding illustrates the significance of task sharing in multiple proxies. The resulted load balancing among proxies has provided a better video quality delivered to a larger audience.

  20. Respiratory sleep disorders in patients with congestive heart failure.

    PubMed

    Naughton, Matthew T

    2015-08-01

    Respiratory sleep disorders (RSD) occur in about 40-50% of patients with symptomatic congestive heart failure (CHF). Obstructive sleep apnea (OSA) is considered a cause of CHF, whereas central sleep apnea (CSA) is considered a response to heart failure, perhaps even compensatory. In the setting of heart failure, continuous positive airway pressure (CPAP) has a definite role in treating OSA with improvements in cardiac parameters expected. However in CSA, CPAP is an adjunctive therapy to other standard therapies directed towards the heart failure (pharmacological, device and surgical options). Whether adaptive servo controlled ventilatory support, a variant of CPAP, is beneficial is yet to be proven. Supplemental oxygen therapy should be used with caution in heart failure, in particular, by avoiding hyperoxia as indicated by SpO2 values >95%.

  1. Weighted congestion coefficient feedback in intelligent transportation systems

    NASA Astrophysics Data System (ADS)

    Dong, Chuan-Fei; Ma, Xu; Wang, Bing-Hong

    2010-03-01

    In traffic systems, a reasonable information feedback can improve road capacity. In this Letter, we study dynamics of traffic flow with real-time information. And the influence of a feedback strategy named Weighted Congestion Coefficient Feedback Strategy (WCCFS) is introduced, based on a two-route scenario in which dynamic information can be generated and displayed on the board to guide road users to make a choice. Our model incorporates the effects of adaptability into the cellular automaton models of traffic flow and simulation results adopting this optimal information feedback strategy have demonstrated high efficiency in controlling spatial distribution of traffic patterns compared with the other three information feedback strategies, i.e., vehicle number and flux.

  2. Driving with a Congestion Assistant; mental workload and acceptance.

    PubMed

    Brookhuis, Karel A; van Driel, Cornelie J G; Hof, Tineke; van Arem, Bart; Hoedemaeker, Marika

    2009-11-01

    New driver support systems are developed and introduced to the market at increasing speed. In conditions of traffic congestion drivers may be supported by a "Congestion Assistant", a system that combines the features of a Congestion Warning System (acoustic warning and gas pedal counterforce) and a Stop & Go system (automatic gas and brake pedal during congestion). To gain understanding of the effects of driving with a Congestion Assistant on drivers, mental workload of drivers was registered under different conditions as well as acceptance of the system. Mental workload was measured by means of physiological registrations, i.e. heart rate, a secondary task and with the aid of subjective scaling techniques. Acceptance was measured with an acceptance scale. The study was carried out in an advanced driving simulator. Driving with the Congestion Assistant while in congestion potentially leads to decreased driver mental workload, whereas just before congestion starts, i.e. developing just noticeable, the system may add to the workload of the driver. Acceptance is generally high after experiencing the system, though not in all respects.

  3. Treatment of Congestive Heart Failure with Triamterene

    PubMed Central

    Wener, J.; Schucher, R.; Friedman, R.

    1965-01-01

    Triamterene, a newer oral diuretic, was administered to nine hospitalized patients with congestive heart failure for an average of 15 days, and to 22 ambulatory patients for a period of three to 11 months. The daily dosage of triamterene ranged from 50 to 250 mg., but usually 100-200 mg. was administered daily in two divided doses, with or without the addition of 50 mg. of hydrochlorothiazide daily. Triamterene is a safe and effective diuretic at doses of 100-200 mg. daily and no drug tolerance develops with long-term therapy. However, when used alone, it is not as effective as hydrochlorothiazide, but in combination with the latter drug the resultant diuresis is unsurpassed by any other oral diuretic therapy that we have used to date. Triamterene itself does not produce kaliuresis and it blocks thiazide-induced kaliuresis. Serum uric acid levels may rise slightly, but no clinical gout was seen in this study. PMID:14259336

  4. Demand and Congestion in Multiplex Transportation Networks.

    PubMed

    Chodrow, Philip S; Al-Awwad, Zeyad; Jiang, Shan; González, Marta C

    Urban transportation systems are multimodal, sociotechnical systems; however, while their multimodal aspect has received extensive attention in recent literature on multiplex networks, their sociotechnical aspect has been largely neglected. We present the first study of an urban transportation system using multiplex network analysis and validated Origin-Destination travel demand, with Riyadh's planned metro as a case study. We develop methods for analyzing the impact of additional transportation layers on existing dynamics, and show that demand structure plays key quantitative and qualitative roles. There exist fundamental geometrical limits to the metro's impact on traffic dynamics, and the bulk of environmental accrue at metro speeds only slightly faster than those planned. We develop a simple model for informing the use of additional, "feeder" layers to maximize reductions in global congestion. Our techniques are computationally practical, easily extensible to arbitrary transportation layers with complex transfer logic, and implementable in open-source software.

  5. Demand and Congestion in Multiplex Transportation Networks

    PubMed Central

    al-Awwad, Zeyad; Jiang, Shan; González, Marta C.

    2016-01-01

    Urban transportation systems are multimodal, sociotechnical systems; however, while their multimodal aspect has received extensive attention in recent literature on multiplex networks, their sociotechnical aspect has been largely neglected. We present the first study of an urban transportation system using multiplex network analysis and validated Origin-Destination travel demand, with Riyadh’s planned metro as a case study. We develop methods for analyzing the impact of additional transportation layers on existing dynamics, and show that demand structure plays key quantitative and qualitative roles. There exist fundamental geometrical limits to the metro’s impact on traffic dynamics, and the bulk of environmental accrue at metro speeds only slightly faster than those planned. We develop a simple model for informing the use of additional, “feeder” layers to maximize reductions in global congestion. Our techniques are computationally practical, easily extensible to arbitrary transportation layers with complex transfer logic, and implementable in open-source software. PMID:27657738

  6. Pelvic congestion syndrome and pelvic varicosities.

    PubMed

    Koo, Sonya; Fan, Chieh-Min

    2014-06-01

    Pelvic venous insufficiency (PVI), defined as retrograde flow in the gonadal and internal iliac veins, is the underlying cause of pelvic congestion syndrome (PCS), a common cause of disabling chronic pelvic pain in women of child-bearing age. PCS is a chronic pain syndrome characterized by positional pelvic pain that is worse in the upright position and is associated with pelvic and vulvar varicosities as well as symptoms of dyspareunia and postcoital pain. Through collaterals to the lower extremity venous system, PVI may also contribute to varicose vein formation and recurrence in the lower extremities. Endovascular embolization of the ovarian and internal iliac veins has become the treatment of choice for PVI and PCS. This article reviews the pelvic retroperitoneal venous anatomy, pathophysiology of PCS, treatment options and techniques, and clinical outcomes of embolotherapy for PCS.

  7. Crystal structures of three sterically congested disilanes

    PubMed Central

    Pichaandi, Kothanda Rama

    2017-01-01

    In the three sterically congested silanes, C24H38Si2 (1) (1,1,2,2-tetra­isopropyl-1,2-di­phenyl­disilane), C24H34Br4Si2 (2) [1,1,2,2-tetra­kis­(2-bromo­propan-2-yl)-1,2-di­phenyl­disilane] and C32H38Si2 (3) (1,2-di-tert-butyl-1,1,2,2-tetra­phenyl­disilane), the Si—Si bond length is shortest in (1) and longest in (2), with (3) having an inter­mediate value, which parallels the increasing steric congestion. A comparison of the two isopropyl derivatives, (1 and 2), shows a significant increase in the Si—C(ipso) distance with the introduction of bromine. Also, in the brominated compound 2, attractive inter­molecular Br⋯Br inter­actions exist with Br⋯Br separations ca 0.52 Å shorter than the sum of the van der Waals radii. In compound 2, one of the bromo­isopropyl groups is rotationally disordered in an 0.8812 (9):0.1188 (9) ratio. Compound 3 exhibits ‘whole mol­ecule’ disorder in a 0.9645 (7):0.0355 (7) ratio with the Si—Si bonds in the two components making an angle of ca 66°. PMID:28316829

  8. Agent Reward Shaping for Alleviating Traffic Congestion

    NASA Technical Reports Server (NTRS)

    Tumer, Kagan; Agogino, Adrian

    2006-01-01

    Traffic congestion problems provide a unique environment to study how multi-agent systems promote desired system level behavior. What is particularly interesting in this class of problems is that no individual action is intrinsically "bad" for the system but that combinations of actions among agents lead to undesirable outcomes, As a consequence, agents need to learn how to coordinate their actions with those of other agents, rather than learn a particular set of "good" actions. This problem is ubiquitous in various traffic problems, including selecting departure times for commuters, routes for airlines, and paths for data routers. In this paper we present a multi-agent approach to two traffic problems, where far each driver, an agent selects the most suitable action using reinforcement learning. The agent rewards are based on concepts from collectives and aim to provide the agents with rewards that are both easy to learn and that if learned, lead to good system level behavior. In the first problem, we study how agents learn the best departure times of drivers in a daily commuting environment and how following those departure times alleviates congestion. In the second problem, we study how agents learn to select desirable routes to improve traffic flow and minimize delays for. all drivers.. In both sets of experiments,. agents using collective-based rewards produced near optimal performance (93-96% of optimal) whereas agents using system rewards (63-68%) barely outperformed random action selection (62-64%) and agents using local rewards (48-72%) performed worse than random in some instances.

  9. Investigation of 40Gb/s WDM multi-casting using a hybrid integrated Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Reading-Picopoulos, Dimitri; Penty, Richard V.; White, Ian H.

    2006-10-01

    All-optical multi-casting permits the establishment of high-quality, high-bandwidth point-to-multipoint applications in metropolitan area networks by diffusing an incoming data carrying wavelength onto a number of outgoing wavelengths. With the proliferation of hybrid Wavelength Division Multiplex (WDM)/Optical Time Division Multiplex (OTDM) networks, the ability to perform high-speed broadcasting of OTDM signals at multiple wavelengths will prove an efficient method in the dissemination of information over WDM. Current approaches to WDM multi-casting involve the execution of multiple cycles of optical-electronic-optical conversion, thus necessitating the use of costly high-speed electronics and optoelectronics. All-optical multi-casting would therefore remove such constraints while concurrently providing for a higher level of network transparency thereby improving network management and performance. To date, the issue has most promisingly been addressed through the manipulation of nonlinear phenomena within semiconductor optical amplifiers (SOA). The demonstrations so far however, have exhibited either low conversion efficiency or operating speed constraint or a complicated setup. All-optical Mach-Zehnder interferometer (MZI) approaches are therefore particularly attractive as they are not limited by the aforementioned constraints, while still offering a low switching power requirement at high-speed and a high level of integratability. In this paper we present a detailed model replicating a 40Gb/s experimental setup in order to investigate the operational limit of the MZI when employed in WDM multi-casting. Through simulation we examine the factors determining the constraints imposed on the maximum number of output multi-cast channels that can be achieved using such a device and establish its suitability as a next-generation all-optical multi-caster.

  10. WDM/TDM PON experiments using the AWG free spectral range periodicity to transmit unicast and multicast data.

    PubMed

    Bock, Carlos; Prat, Josep

    2005-04-18

    A hybrid WDM/TDM PON architecture implemented by means of two cascaded Arrayed Waveguide Gratings (AWG) is presented. Using the Free Spectral Range (FSR) periodicity of AWGs we transmit unicast and multicast traffic on different wavelengths to each Optical Network Unit (ONU). The OLT is equipped with two laser stacks, a tunable one for unicast transmission and a fixed one for multicast transmission. We propose the ONU to be reflective in order to avoid any light source at the Costumer Premises Equipment (CPE). Optical transmission tests demonstrate correct transmission at 2.5 Gbps up to 30 km.

  11. Involvement of systemic venous congestion in heart failure.

    PubMed

    Rubio Gracia, J; Sánchez Marteles, M; Pérez Calvo, J I

    2017-04-01

    Systemic venous congestion has gained significant importance in the interpretation of the pathophysiology of acute heart failure, especially in the development of renal function impairment during exacerbations. In this study, we review the concept, clinical characterisation and identification of venous congestion. We update current knowledge on its importance in the pathophysiology of acute heart failure and its involvement in the prognosis. We pay special attention to the relationship between abdominal congestion, the pulmonary interstitium as filtering membrane, inflammatory phenomena and renal function impairment in acute heart failure. Lastly, we review decongestion as a new therapeutic objective and the measures available for its assessment.

  12. Bortezomib-induced Severe Congestive Heart Failure

    PubMed Central

    Jerkins, James H.; Suciu, Anca; Mazimba, Sula; Calvo, Alejandro

    2010-01-01

    The clinical manifestations of anti-cancer drug associated cardiac side effects are diverse and can range from acutely induced cardiac arrhythmias to severe contractile dysfunction, and potentially fatal heart failure. Anthracyclines and trastuzumab cardiac toxicity have been well described and left ventricular ejection fraction (LVEF) evaluation is commonly performed before their use. Bortezomib (Velcade), a potent, specific and reversible proteasome inhibitor is approved for treatment of multiple myeloma (MM). The incidence of cardiac failure associated with bortezomib therapy in clinical trials remains incidental. Acute exacerbation of pre-existing congestive cardiac failure has been associated with this therapy but de novo cardiomyopathy has been reported in only one patient receiving bortezomib for small cell lung cancer. As a result, cardiac evaluation is not normally ordered before its use. We describe a 50-year-old female with newly diagnosed MM and no risk factors for cardiac disease that unexpectedly developed florid heart failure after 2 cycles of bortezomib and low-dose dexamethasone. 2-D echocardiogram showed dilated cardiomyopathy with severely decreased LVEF; no changes consistent with amyloid deposits or myocardial scarring were described. Coronary angiogram ruled out coronary artery disease. The mechanism of bortezomib-induced cardiomyopathy has been postulated to be through fluid retention. Based on literature review we hypothesize that the disruption of the ubiquitin-proteasome system by bortezomib may cause cardiomyopathy and severe cardiac failure. As Bortezomib is a new and promising therapy for MM patients, we recommend routinely monitoring cardiac parameters in patients undergoing this treatment.

  13. Route Optimization for Offloading Congested Meter Fixes

    NASA Technical Reports Server (NTRS)

    Xue, Min; Zelinski, Shannon

    2016-01-01

    The Optimized Route Capability (ORC) concept proposed by the FAA facilitates traffic managers to identify and resolve arrival flight delays caused by bottlenecks formed at arrival meter fixes when there exists imbalance between arrival fixes and runways. ORC makes use of the prediction capability of existing automation tools, monitors the traffic delays based on these predictions, and searches the best reroutes upstream of the meter fixes based on the predictions and estimated arrival schedules when delays are over a predefined threshold. Initial implementation and evaluation of the ORC concept considered only reroutes available at the time arrival congestion was first predicted. This work extends previous work by introducing an additional dimension in reroute options such that ORC can find the best time to reroute and overcome the 'firstcome- first-reroute' phenomenon. To deal with the enlarged reroute solution space, a genetic algorithm was developed to solve this problem. Experiments were conducted using the same traffic scenario used in previous work, when an arrival rush was created for one of the four arrival meter fixes at George Bush Intercontinental Houston Airport. Results showed the new approach further improved delay savings. The suggested route changes from the new approach were on average 30 minutes later than those using other approaches, and fewer numbers of reroutes were required. Fewer numbers of reroutes reduce operational complexity and later reroutes help decision makers deal with uncertain situations.

  14. Implementation of Both High-Speed Transmission and Quality of System for Internet Protocol Multicasting Services

    NASA Astrophysics Data System (ADS)

    Son, Byounghee; Park, Youngchoong; Nahm, Euiseok

    The paper introduces both high-speed transmission and quality of system to offer the Internet services on a HFC (Hybrid Fiber Coaxial) network. This utilizes modulating the phase and the amplitude to the signal of the IPMS (Internet Protocol Multicasting Service). An IP-cable transmitter, IP-cable modem, and IP-cable management servers that support 30-Mbps IPMS on the HFC were developed. The system provides a 21Mbps HDTV transporting stream on a cable TV network. It can sustain a clear screen for a long time.

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

    PubMed Central

    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

  16. Toward multi-Gbps indoor optical wireless multicasting system employing passive diffractive optics.

    PubMed

    Oh, C W; Huijskens, F M; Cao, Z; Tangdiongga, E; Koonen, A M J

    2014-05-01

    This Letter presents the evaluation and demonstration of an optical free-space (FS) multicasting system for multi-Gigabits-per-second (multi-Gbps) indoor transmission. These simultaneous line-of-sight links are formed by infrared beams and are beam-steered using a passive diffraction grating. The experiment has resulted in error-free links (bit error rate <10(-9) at 2.5 Gbps on-off keying) and is scalable to support higher data rates. This system is proposed for short-range optical wireless communication and can be seamlessly integrated in in-building fiber networks.

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

    PubMed

    Jung, Young-Ho; Choi, Jihoon

    2017-02-25

    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.

  18. Properties of volume-capacity ratio in congested complex networks

    NASA Astrophysics Data System (ADS)

    Zhu, Zhi-Hong; Zheng, Jian-Feng; Gao, Zi-You; Du, Hao-Ming

    2014-04-01

    The volume-capacity ratio (v/c) is one of the most important indexes to measure the congestion of a traffic network. If v/c is very small, the traffic demand is deficient and/or the transportation supply or capacity is surplus, leading to a waste of capacity; on the contrary, a large value of v/c means that the traffic network is seriously congested. This paper investigates the properties of v/c in complex small-world and scale-free networks by introducing the congestion effects, described by link cost functions. The relationship between v/c and the degree of the node is mainly discussed. Finally, a simple strategy is presented to balance the tradeoff between traffic congestion and a waste of capacity.

  19. Efficiency and profit in the NYISO transmission congestion contract market

    SciTech Connect

    Hadsell, Lester; Shawky, Hany A.

    2009-11-15

    Evidence of speculator profit and TCC price less than congestion charges suggests that additional competition in the TCC auction should be encouraged as a way to increase efficiency and lower the price of this ''insurance'' for hedgers. (author)

  20. A Hybrid Differential Invasive Weed Algorithm for Congestion Management

    NASA Astrophysics Data System (ADS)

    Basak, Aniruddha; Pal, Siddharth; Pandi, V. Ravikumar; Panigrahi, B. K.; Das, Swagatam

    This work is dedicated to solve the problem of congestion management in restructured power systems. Nowadays we have open access market which pushes the power system operation to their limits for maximum economic benefits but at the same time making the system more susceptible to congestion. In this regard congestion management is absolutely vital. In this paper we try to remove congestion by generation rescheduling where the cost involved in the rescheduling process is minimized. The proposed algorithm is a hybrid of Invasive Weed Optimization (IWO) and Differential Evolution (DE). The resultant hybrid algorithm was applied on standard IEEE 30 bus system and observed to beat existing algorithms like Simple Bacterial foraging (SBF), Genetic Algorithm (GA), Invasive Weed Optimization (IWO), Differential Evolution (DE) and hybrid algorithms like Hybrid Bacterial Foraging and Differential Evolution (HBFDE) and Adaptive Bacterial Foraging with Nelder Mead (ABFNM).

  1. Congestion Induced by the Structure of Multiplex Networks

    NASA Astrophysics Data System (ADS)

    Solé-Ribalta, Albert; Gómez, Sergio; Arenas, Alex

    2016-03-01

    Multiplex networks are representations of multilayer interconnected complex networks where the nodes are the same at every layer. They turn out to be good abstractions of the intricate connectivity of multimodal transportation networks, among other types of complex systems. One of the most important critical phenomena arising in such networks is the emergence of congestion in transportation flows. Here, we prove analytically that the structure of multiplex networks can induce congestion for flows that otherwise would be decongested if the individual layers were not interconnected. We provide explicit equations for the onset of congestion and approximations that allow us to compute this onset from individual descriptors of the individual layers. The observed cooperative phenomenon is reminiscent of Braess' paradox in which adding extra capacity to a network when the moving entities selfishly choose their route can in some cases reduce overall performance. Similarly, in the multiplex structure, the efficiency in transportation can unbalance the transportation loads resulting in unexpected congestion.

  2. Traffic congestion and the lifetime of networks with moving nodes

    NASA Astrophysics Data System (ADS)

    Yang, Xianxia; Li, Jie; Pu, Cunlai; Yan, Meichen; Sharafat, Rajput Ramiz; Yang, Jian; Gakis, Konstantinos; Pardalos, Panos M.

    2017-01-01

    For many power-limited networks, such as wireless sensor networks and mobile ad hoc networks, maximizing the network lifetime is the first concern in the related designing and maintaining activities. We study the network lifetime from the perspective of network science. In our model, nodes are initially assigned a fixed amount of energy moving in a square area and consume the energy when delivering packets. We obtain four different traffic regimes: no, slow, fast, and absolute congestion regimes, which are basically dependent on the packet generation rate. We derive the network lifetime by considering the specific regime of the traffic flow. We find that traffic congestion inversely affects network lifetime in the sense that high traffic congestion results in short network lifetime. We also discuss the impacts of factors such as communication radius, node moving speed, routing strategy, etc., on network lifetime and traffic congestion.

  3. Traffic congestion and the lifetime of networks with moving nodes.

    PubMed

    Yang, Xianxia; Li, Jie; Pu, Cunlai; Yan, Meichen; Sharafat, Rajput Ramiz; Yang, Jian; Gakis, Konstantinos; Pardalos, Panos M

    2017-01-01

    For many power-limited networks, such as wireless sensor networks and mobile ad hoc networks, maximizing the network lifetime is the first concern in the related designing and maintaining activities. We study the network lifetime from the perspective of network science. In our model, nodes are initially assigned a fixed amount of energy moving in a square area and consume the energy when delivering packets. We obtain four different traffic regimes: no, slow, fast, and absolute congestion regimes, which are basically dependent on the packet generation rate. We derive the network lifetime by considering the specific regime of the traffic flow. We find that traffic congestion inversely affects network lifetime in the sense that high traffic congestion results in short network lifetime. We also discuss the impacts of factors such as communication radius, node moving speed, routing strategy, etc., on network lifetime and traffic congestion.

  4. Reducing congestion on complex networks by dynamic relaxation processes

    NASA Astrophysics Data System (ADS)

    Macri, Pablo A.; Pastore y Piontti, Ana L.; Braunstein, Lidia A.

    2007-12-01

    We study the effects of relaxational dynamics on the congestion pressure in general transport networks. We show that the congestion pressure is reduced in scale-free networks if a relaxation mechanism is utilized, while this is in general not the case for non-scale-free graphs such as random graphs. We also present evidence supporting the idea that the emergence of scale-free networks arise from optimization mechanisms to balance the load of the networks nodes.

  5. Atrial natriuretic factor binding sites in experimental congestive heart failure

    SciTech Connect

    Bianchi, C.; Thibault, G.; Wrobel-Konrad, E.; De Lean, A.; Genest, J.; Cantin, M. )

    1989-10-01

    A quantitative in vitro autoradiographic study was performed on the aorta, renal glomeruli, and adrenal cortex of cardiomyopathic hamsters in various stages of heart failure and correlated, in some instances, with in vivo autoradiography. The results indicate virtually no correlation between the degree of congestive heart failure and the density of 125I-labeled atrial natriuretic factor ((Ser99, Tyr126)ANF) binding sites (Bmax) in the tissues examined. Whereas the Bmax was increased in the thoracic aorta in moderate and severe heart failure, there were no significant changes in the zona glomerulosa. The renal glomeruli Bmax was lower in mild and moderate heart failure compared with control and severe heart failure. The proportion of ANF B- and C-receptors was also evaluated in sections of the aorta, adrenal, and kidney of control and cardiomyopathic hamsters with severe heart failure. (Arg102, Cys121)ANF (des-(Gln113, Ser114, Gly115, Leu116, Gly117) NH2) (C-ANF) at 10(-6) M displaced approximately 505 of (Ser99, Tyr126)125I-ANF bound in the aorta and renal glomeruli and approximately 20% in the adrenal zona glomerulosa in both series of animals. These results suggest that ANF may exert a buffering effect on the vasoconstriction of heart failure and to a certain extent may inhibit aldosterone secretion. The impairment of renal sodium excretion does not appear to be related to glomerular ANF binding sites at any stage of the disease.

  6. Chronic vagal stimulation in patients with congestive heart failure.

    PubMed

    De Ferrari, Gaetano M; Sanzo, Antonio; Schwartz, Peter J

    2009-01-01

    Increased sympathetic and reduced vagal activity predict increased mortality in patients with congestive heart failure (CHF). Experimentally, vagal stimulation (VS) is protective both during acute myocardial ischemia and in chronic heart failure. In man, VS is used in refractory epilepsy but has never been used in cardiovascular diseases. Thus, there is a strong rationale to investigate the effects of chronic VS in patients with CHF. We assesses the feasibility and safety of chronic VS with CardioFit (BioControl Medical), a VS implantable system delivering pulses synchronous with heart beats to the right cervical vagus nerve in a preliminary pilot study in eight advanced CHF patients with favorable results, and subsequently in a larger multicenter study. Overall, 32 patients have been successfully implanted (mostly in NYHA Class III; mean age 56 years, ischemic etiology in 69%; prior implantable cardioverter-defibrillator (ICD) in 63%; concomitant beta blocker and angiotensin converting enzyme inhibitor (ACE-I) or angiotensin receptor blocker (ARB) in 100%). Preliminary results confirm feasibility of the study, an acceptable side effect profile and promising preliminary efficacy data. Several mechanisms may contribute to the beneficial effect observed in patients with heart failure. Should these results be confirmed in larger controlled studies, chronic vagal stimulation could be a further treatment option for CHF patients, possibly integrated with defibrillator and resynchronization therapies.

  7. [Congestive heart failure in patients with chronic kidney disease].

    PubMed

    Poskurica, Mileta; Petrović, Dejan

    2014-01-01

    Cardiovascular disorders are the most frequent cause of death (46-60%) among patients with advanced chronic renal failure (CRF), and on dialysis treatment. Uremic cardiomyopathy is the basic pathophysiologic substrate, whereas ischemic heart disease (IHD) and anemia are the most important contributing factors. Associated with well-know risk factors and specific disorders for terminal kidney failure and dialysis, the aforementioned factors instigate congestive heart failure (CHF). Suspected CHF is based on the anamnesis, clinical examination and ECG, while it is confirmed and defined more precisely on the basis of echocardiography and radiology examination. Biohumoral data (BNP, NT-proBNP) are not sufficiently reliable because of specific volemic fluctuation and reduced natural clearance. Therapy approach is similar to the one for the general population: ACEI, ARBs, β-blockers, inotropic drugs and diuretics. Hypervolemia and most of the related symptoms can be kept under control effectively by the isolated or ultrafiltation, in conjunction with dialysis, during the standard bicarbonate hemodialysis or hemodiafiltration. In the same respect peritoneal dialysis is efficient for the control of hypervolemia symptoms, mainly during the first years of its application and in case of the lower NYHA class (II°/III°). In general, heart support therapy, surgical interventions of the myocardium and valve replacement are rarely used in patients on dialysis, whereas revascularization procedures are beneficial for associated IHD. In selected cases the application of cardiac resynchronization and/or implantation of a cardioverter defibrillator are advisable.

  8. Congestion, air pollution, and road fatalities in urban areas.

    PubMed

    Shefer, D

    1994-08-01

    The continuous rapid growth in vehicle miles travelled coupled with the rapid increase in traffic congestion on highways of virtually every large urban area, explain a major portion of the observed deterioration of urban air quality. To halt this deterioration and to secure safe and healthy environments and improve the quality of life in our cities, it is useful to initiate and implement programs that treat jointly traffic congestion, air quality, and road safety. Market-based strategies, driven by price mechanisms, have been proposed as the best and most efficient way to decrease traffic congestion and to reduce vehicle emission. Congestion pricing, emission fees, reducing emissions of high-polluting vehicles, and introducing more efficient vehicle and/or fuel technologies are not mutually exclusive strategies and therefore they can be employed jointly within an overall strategy. In view of the conflicting objectives that may exist between improving urban air quality and reducing road fatalities and traffic congestion, it is of great importance to investigate thoroughly these functional relationships. The results of such studies will help decision makers identify the "socially optimal level of congestion" that will yield the highest net social benefit.

  9. A theory of traffic congestion at moving bottlenecks

    NASA Astrophysics Data System (ADS)

    Kerner, Boris S.; Klenov, Sergey L.

    2010-10-01

    The physics of traffic congestion occurring at a moving bottleneck on a multi-lane road is revealed based on the numerical analyses of vehicular traffic with a discrete stochastic traffic flow model in the framework of three-phase traffic theory. We find that there is a critical speed of a moving bottleneck at which traffic breakdown, i.e. a first-order phase transition from free flow to synchronized flow, occurs spontaneously at the moving bottleneck, if the flow rate upstream of the bottleneck is great enough. The greater the flow rate, the higher the critical speed of the moving bottleneck. A diagram of congested traffic patterns at the moving bottleneck is found, which shows regions in the flow-rate-moving-bottleneck-speed plane in which congested patterns emerge spontaneously or can be induced through large enough disturbances in an initial free flow. A comparison of features of traffic breakdown and resulting congested patterns at the moving bottleneck with known ones at an on-ramp (and other motionless) bottleneck is made. Nonlinear features of complex interactions and transformations of congested traffic patterns occurring at on- and off-ramp bottlenecks due to the existence of the moving bottleneck are found. The physics of the phenomenon of traffic congestion due to 'elephant racing' on a multi-lane road is revealed.

  10. Local empathy provides global minimization of congestion in communication networks

    NASA Astrophysics Data System (ADS)

    Meloni, Sandro; Gómez-Gardeñes, Jesús

    2010-11-01

    We present a mechanism to avoid congestion in complex networks based on a local knowledge of traffic conditions and the ability of routers to self-coordinate their dynamical behavior. In particular, routers make use of local information about traffic conditions to either reject or accept information packets from their neighbors. We show that when nodes are only aware of their own congestion state they self-organize into a hierarchical configuration that delays remarkably the onset of congestion although leading to a sharp first-order-like congestion transition. We also consider the case when nodes are aware of the congestion state of their neighbors. In this case, we show that empathy between nodes is strongly beneficial to the overall performance of the system and it is possible to achieve larger values for the critical load together with a smooth, second-order-like, transition. Finally, we show how local empathy minimize the impact of congestion as much as global minimization. Therefore, here we present an outstanding example of how local dynamical rules can optimize the system’s functioning up to the levels reached using global knowledge.

  11. Optimal structure of complex networks for minimizing traffic congestion.

    PubMed

    Zhao, Liang; Cupertino, Thiago Henrique; Park, Kwangho; Lai, Ying-Cheng; Jin, Xiaogang

    2007-12-01

    To design complex networks to minimize traffic congestion, it is necessary to understand how traffic flow depends on network structure. We study data packet flow on complex networks, where the packet delivery capacity of each node is not fixed. The optimal configuration of capacities to minimize traffic congestion is derived and the critical packet generating rate is determined, below which the network is at a free flow state but above which congestion occurs. Our analysis reveals a direct relation between network topology and traffic flow. Optimal network structure, free of traffic congestion, should have two features: uniform distribution of load over all nodes and small network diameter. This finding is confirmed by numerical simulations. Our analysis also makes it possible to theoretically compare the congestion conditions for different types of complex networks. In particular, we find that network with low critical generating rate is more susceptible to congestion. The comparison has been made on the following complex-network topologies: random, scale-free, and regular.

  12. Local empathy provides global minimization of congestion in communication networks.

    PubMed

    Meloni, Sandro; Gómez-Gardeñes, Jesús

    2010-11-01

    We present a mechanism to avoid congestion in complex networks based on a local knowledge of traffic conditions and the ability of routers to self-coordinate their dynamical behavior. In particular, routers make use of local information about traffic conditions to either reject or accept information packets from their neighbors. We show that when nodes are only aware of their own congestion state they self-organize into a hierarchical configuration that delays remarkably the onset of congestion although leading to a sharp first-order-like congestion transition. We also consider the case when nodes are aware of the congestion state of their neighbors. In this case, we show that empathy between nodes is strongly beneficial to the overall performance of the system and it is possible to achieve larger values for the critical load together with a smooth, second-order-like, transition. Finally, we show how local empathy minimize the impact of congestion as much as global minimization. Therefore, here we present an outstanding example of how local dynamical rules can optimize the system's functioning up to the levels reached using global knowledge.

  13. Reducing Traffic Congestions by Introducing CACC-Vehicles on a Multi-Lane Highway Using Agent-Based Approach

    NASA Technical Reports Server (NTRS)

    Arnaout, Georges M.; Bowling, Shannon R.

    2011-01-01

    Traffic congestion is an ongoing problem of great interest to researchers from different areas in academia. With the emerging technology for inter-vehicle communication, vehicles have the ability to exchange information with predecessors by wireless communication. In this paper, we present an agent-based model of traffic congestion and examine the impact of having CACC (Cooperative Adaptive Cruise Control) embedded vehicle(s) on a highway system consisting of 4 traffic lanes without overtaking. In our model, CACC vehicles adapt their acceleration/deceleration according to vehicle-to-vehicle inter-communication. We analyze the average speed of the cars, the shockwaves, and the evolution of traffic congestion throughout the lifecycle of the model. The study identifies how CACC vehicles affect the dynamics of traffic flow on a complex network and reduce the oscillatory behavior (stop and go) resulting from the acceleration/deceleration of the vehicles.

  14. Tunable optical multicasting of PDM-OFDM signals by novel polarization-interleaved multi-pump FWM scheme.

    PubMed

    Zhu, Paikun; Li, Juhao; Chen, Yuanxiang; Zhou, Peng; Chen, Zhangyuan; He, Yongqi

    2016-11-14

    Optical multicasting that supports point-to-multipoint traffic replication can be one of the necessary techniques in next-generation all-optical elastic networks. In this paper, we propose an optical multicasting approach for polarization-division-multiplexing (PDM) orthogonal frequency division multiplexing (OFDM) signals based on a novel polarization-interleaved multi-pump (PIMP) four-wave mixing (FWM) scheme in highly nonlinear fiber (HNLF). Besides format transparency and the support of PDM signals, the scheme further enables wide spectral tunability of generated replicas. The pump frequency arrangement for the scheme is presented, which successfully prevents the replicas from being superimposed by unwanted FWM components during tuning. We experimentally demonstrate multicasting operation of a 3-band 100-Gb/s PDM-OFDM signal. With different input positions, 1.4 and 1.6 Terahertz tuning ranges of four replicas are achieved with Q-factor performance better than the forward error correction threshold. Tunable replica spacing from 100-GHz to 250-GHz are also verified. In addition, the scalability of the scheme is demonstrated via 5-pump multicasting, successfully generating a total of 14 replicas.

  15. An Evaluation of the Network Efficiency Required in Order to Support Multicast and Synchronous Distributed Learning Network Traffic

    DTIC Science & Technology

    2003-09-01

    Learning, Network Protocol, PIM, DVMRP, IGMP , SAP/SDP, IGMP Snooping, Dense Mode, Sparse Mode 16. PRICE CODE 17. SECURITY CLASSIFICATION OF...Announcement Protocol (SAP) ..........28 2. Session Description Protocol (SDP) ...........30 B. INTERNET GROUP MANAGEMENT PROTOCOL ( IGMP ) .........31 1...38 4. IGMP Snooping ................................40 C. DISTANCE VECTOR MULTICASTING ROUTING PROTOCOL (DVMRP

  16. A model to identify urban traffic congestion hotspots in complex networks

    PubMed Central

    Solé-Ribalta, Albert; Gómez, Sergio

    2016-01-01

    The rapid growth of population in urban areas is jeopardizing the mobility and air quality worldwide. One of the most notable problems arising is that of traffic congestion. With the advent of technologies able to sense real-time data about cities, and its public distribution for analysis, we are in place to forecast scenarios valuable for improvement and control. Here, we propose an idealized model, based on the critical phenomena arising in complex networks, that allows to analytically predict congestion hotspots in urban environments. Results on real cities’ road networks, considering, in some experiments, real traffic data, show that the proposed model is capable of identifying susceptible junctions that might become hotspots if mobility demand increases. PMID:27853535

  17. A model to identify urban traffic congestion hotspots in complex networks

    NASA Astrophysics Data System (ADS)

    Solé-Ribalta, Albert; Gómez, Sergio; Arenas, Alex

    2016-10-01

    The rapid growth of population in urban areas is jeopardizing the mobility and air quality worldwide. One of the most notable problems arising is that of traffic congestion. With the advent of technologies able to sense real-time data about cities, and its public distribution for analysis, we are in place to forecast scenarios valuable for improvement and control. Here, we propose an idealized model, based on the critical phenomena arising in complex networks, that allows to analytically predict congestion hotspots in urban environments. Results on real cities' road networks, considering, in some experiments, real traffic data, show that the proposed model is capable of identifying susceptible junctions that might become hotspots if mobility demand increases.

  18. A model to identify urban traffic congestion hotspots in complex networks.

    PubMed

    Solé-Ribalta, Albert; Gómez, Sergio; Arenas, Alex

    2016-10-01

    The rapid growth of population in urban areas is jeopardizing the mobility and air quality worldwide. One of the most notable problems arising is that of traffic congestion. With the advent of technologies able to sense real-time data about cities, and its public distribution for analysis, we are in place to forecast scenarios valuable for improvement and control. Here, we propose an idealized model, based on the critical phenomena arising in complex networks, that allows to analytically predict congestion hotspots in urban environments. Results on real cities' road networks, considering, in some experiments, real traffic data, show that the proposed model is capable of identifying susceptible junctions that might become hotspots if mobility demand increases.

  19. Enhanced service differentiation for layered video multicast in differentiated service networks

    NASA Astrophysics Data System (ADS)

    Nahm, Kitae; Shin, Jitae; Kim, JongWon; Kuo, C.-C. Jay

    2002-01-01

    An enhanced network service model for layered video multicast applications is presented for differentiated service (Diffserv) networks in this work, which consists of enhanced active queue management (AQM) and hierarchial priority marking. It is found from experiments that a straightforward application of the receiver-driven layer multicast (RLM) model to the Diffserv network may perform poorer than to the best-effort Internet, since RLM applications could behave like unresponsive flows and conflict with Diffserv active queues. To fix this problem, we present three sets of extended RED/RIO parameters as the enhanced AQM model, which is designed to be generally applicable to service protection as well as to support RLM traffic in Diffserv networks. Furthermore, to take advantage of the priority service in Diffserv networks, we present a priority marking model of RLM video layers that conform to the priority marking architecture of Dffserv networks. It is shown by simulation experiments that the proposed network service enhancement model improves the stability of the join experiment and reduces the packet loss rate to support RLM traffic in Diffserv networks.

  20. Comparative Study of Multicast Protection Algorithms Using Shared Links in 100GET Transport Network

    NASA Astrophysics Data System (ADS)

    Sulaiman, Samer; Haidine, Abdelfattah; Lehnert, Ralf; Tuerk, Stefan

    In recent years new challenges have emerged in the telecommunications market resulting from the increase of network traffic and strong competition. Because of that, service providers feel constrained to replace expensive and complex IP-routers with a cheap and simple solution which guarantees the requested quality of services (QoS) with low cost. One of these solutions is to use the Ethernet technology as a switching layer, which results in using the cheap Ethernet services (E-Line, E-LAN and E-Tree) and to replace the expensive IP-routers. To achieve this migration step, new algorithms that support the available as well as the future services have to be developed. In this paper, we investigate the multicast protection issue. Three multicast protection algorithms based on the shared capacity between primary and backup solutions are proposed and evaluated. The blocking probability is used to evaluate the performance of the proposed algorithms. The sub-path algorithm resulted in a low blocking probability compared with the other algorithms.

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

    PubMed

    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.

  2. An efficient mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks

    NASA Astrophysics Data System (ADS)

    Yu, Xiaojun; Xiao, Gaoxi; Cheng, Tee Hiang

    2014-08-01

    This paper proposes an efficient overlay multicast provisioning (OMP) mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks. To facilitate request provisioning, OMP jointly utilizes a data learning (DL) scheme on the IP/MPLS layer for logical link cost estimation, and a lightpath fragmentation (LPF) based method on the WDM layer for improving resource sharing in grooming process. Extensive simulations are carried out to evaluate the performance of OMP mechanism under different traffic loads, with either limited or unlimited port resources. Simulation results demonstrate that OMP significantly outperforms the existing methods. To evaluate the respective influences of the DL scheme and the LPF method on OMP performance, provisioning mechanisms only utilizing either the IP/MPLS layer DL scheme or the WDM layer LPF method are also devised. Comparison results show that both DL and LPF methods help improve OMP blocking performance, and contribution from the DL scheme is more significant when the fixed routing and first-fit wavelength assignment (RWA) strategy is adopted on the WDM layer. Effects of a few other factors, including definition of connection cost to be reported by the WDM layer to the IP/MPLS layer and WDM-layer routing method, on OMP performance are also evaluated.

  3. Experimental Evaluation of Unicast and Multicast CoAP Group Communication

    PubMed Central

    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

  4. Low-power-penalty wavelength multicasting for 36  Gbit/s 16-QAM coherent optical signals in a silicon waveguide.

    PubMed

    Wang, Xiaoyan; Huang, Lingchen; Gao, Shiming

    2014-12-15

    All-optical wavelength multicasting has been experimentally demonstrated for 36 Gbit/s 16-quadrature amplitude modulation signals based on four-wave mixing processes in a silicon waveguide with multiple pumps. In our experiment, dual pumps are injected together with the signal into the waveguide and nine idlers are generated, involving five wavelength multicasting channels. Coherent detection and advanced digital signal processing are employed, and the recovered constellation diagrams of the multicasting idlers show a root-mean-square error vector magnitude degradation as small as 2.74%. The bit error rate (BER) results are measured for these multicasting idlers, and the power penalties are all lower than 0.96 dB at the BER of 3.8×10(-3) (corresponding to the forward error correction threshold).

  5. A Novel Congestion Avoidance Technique for Simultaneous Real-Time Medical Data Transmission.

    PubMed

    Yaakob, Naimah; Khalil, Ibrahim

    2016-03-01

    The use of wireless body sensor networks (WBSN) in medical services aims at providing continuous monitoring of patients' physiological data. However, the scarce resources in WBSN nodes limit their capabilities to cope with massive traffic during multiple, simultaneous data transmissions. This will create a high tendency for congestion, causing severe performance degradation. Congestion may lead to high number of packet loss and unbounded delay which are critical and may lead to wrong diagnosis. This paper, therefore, aims at improving this limitation using a novel congestion avoidance technique to avoid losing real-time and life-critical medical data (e.g., electrocardiogram and electroencephalography) which are vital for diagnosis. The main idea is to integrate the existing rate control scheme of relaxation theory (RT) with a method known as max-min fairness (MMF) to achieve better performance. The MMF can be accomplished using a progressive filling algorithm, which cuts-down excessive sending rates that may overwhelme the limited buffer in WBSN. This paper builds upon our prior study, which provides a preliminary analysis of RT technique in single node. Our current technique integrates the MMF phase to enhance RT performance when the transmission rates exceed certain threshold. Performance evaluation on RT-MMF technique shows remarkable performance improvements, while maintaining the desired quality of service.

  6. Baroreflex Activation Therapy in Congestive Heart Failure: Novel Findings and Future Insights.

    PubMed

    Grassi, Guido; Brambilla, GianMaria; Pizzalla, Daniela Prata; Seravalle, Gino

    2016-08-01

    Congestive heart failure is characterized by hemodynamic and non-hemodynamic abnormalities, the latter including an activation of the sympathetic influences to the heart and peripheral circulation coupled with an impairment of baroreceptor control of autonomic function. Evidence has been provided that both these alterations are hallmark features of the disease with a specific relevance for the disease progression as well as for the development of life-threatening cardiac arrhythmias. In addition, a number of studies have documented in heart failure the adverse prognostic role of the sympathetic and baroreflex alterations, which both are regarded as major independent determinants of cardiovascular morbidity and mortality. This represents the pathophysiological and clinical background for the use of carotid baroreceptor activation therapy in the treatment of congestive heart failure. Promising data collected in experimental animal models of heart failure have supported the recent performance of pilot small-scale clinical studies, aimed at providing initial information in this area. The results of these studies demonstrated the clinical safety and efficacy of the intervention which has been tested in large-scale clinical studies. The present paper will critically review the background and main results of the published studies designed at defining the clinical impact of baroreflex activation therapy in congestive heart failure patients. Emphasis will be given to the strengths and limitations of such studies, which represent the background for the ongoing clinical trials testing the long-term effects of the device in heart failure patients.

  7. Water and sodium in heart failure: a spotlight on congestion.

    PubMed

    Parrinello, Gaspare; Greene, Stephen J; Torres, Daniele; Alderman, Michael; Bonventre, Joseph Vincent; Di Pasquale, Pietro; Gargani, Luna; Nohria, Anju; Fonarow, Gregg C; Vaduganathan, Muthiah; Butler, Javed; Paterna, Salvatore; Stevenson, Lynne Warner; Gheorghiade, Mihai

    2015-01-01

    Despite all available therapies, the rates of hospitalization and death from heart failure (HF) remain unacceptably high. The most common reasons for hospital admission are symptoms related to congestion. During hospitalization, most patients respond well to standard therapy and are discharged with significantly improved symptoms. Post-discharge, many patients receive diligent and frequent follow-up. However, rehospitalization rates remain high. One potential explanation is a persistent failure by clinicians to adequately manage congestion in the outpatient setting. The failure to successfully manage these patients post-discharge may represent an unmet need to improve the way congestion is both recognized and treated. A primary aim of future HF management may be to improve clinical surveillance to prevent and manage chronic fluid overload while simultaneously maximizing the use of evidence-based therapies with proven long-term benefit. Improvement in cardiac function is the ultimate goal and maintenance of a "dry" clinical profile is important to prevent hospital admission and improve prognosis. This paper focuses on methods for monitoring congestion, and strategies for water and sodium management in the context of the complex interplay between the cardiac and renal systems. A rationale for improving recognition and treatment of congestion is also proposed.

  8. Water and Sodium in Heart Failure: A Spotlight on Congestion

    PubMed Central

    Greene, Stephen J.; Torres, Daniele; Alderman, Michael; Bonventre, Joseph Vincent; Di Pasquale, Pietro; Gargani, Luna; Nohria, Anju; Fonarow, Gregg C.; Vaduganathan, Muthiah; Butler, Javed; Paterna, Salvatore; Stevenson, Lynne Warner; Gheorghiade, Mihai

    2015-01-01

    Despite all available therapies, the rates of hospitalization and death from heart failure (HF) remain unacceptably high. The most common reasons for hospital admission are symptoms related to congestion. During hospitalization, most patients respond well to standard therapy and are discharged with significantly improved symptoms. Post-discharge, many patients receive diligent and frequent follow-up. However, rehospitalization rates remain high. One potential explanation is a persistent failure by clinicians to adequately manage congestion in the outpatient setting. The failure to successfully manage these patients post-discharge may represent an unmet need to improve the way congestion is both recognized and treated. A primary aim of future HF management may be to improve clinical surveillance to prevent and manage chronic fluid overload while simultaneously maximizing the use of evidence-based therapies with proven long-term benefit. Improvement in cardiac function is the ultimate goal and maintenance of a “dry” clinical profile is important to prevent hospital admission and improve prognosis. This paper focuses on methods for monitoring congestion, and strategies for water and sodium management in the context of the complex interplay between the cardiac and renal systems. A rationale for improving recognition and treatment of congestion is also proposed. PMID:24942806

  9. Traffic Congestion Detection System through Connected Vehicles and Big Data.

    PubMed

    Cárdenas-Benítez, Néstor; Aquino-Santos, Raúl; Magaña-Espinoza, Pedro; Aguilar-Velazco, José; Edwards-Block, Arthur; Medina Cass, Aldo

    2016-04-28

    This article discusses the simulation and evaluation of a traffic congestion detection system which combines inter-vehicular communications, fixed roadside infrastructure and infrastructure-to-infrastructure connectivity and big data. The system discussed in this article permits drivers to identify traffic congestion and change their routes accordingly, thus reducing the total emissions of CO₂ and decreasing travel time. This system monitors, processes and stores large amounts of data, which can detect traffic congestion in a precise way by means of a series of algorithms that reduces localized vehicular emission by rerouting vehicles. To simulate and evaluate the proposed system, a big data cluster was developed based on Cassandra, which was used in tandem with the OMNeT++ discreet event network simulator, coupled with the SUMO (Simulation of Urban MObility) traffic simulator and the Veins vehicular network framework. The results validate the efficiency of the traffic detection system and its positive impact in detecting, reporting and rerouting traffic when traffic events occur.

  10. Reliability and Congestion Effects on Embedded Cost of Transmission Services

    NASA Astrophysics Data System (ADS)

    Shooshtari, Alireza Tavakoli; Joorabian, Mahmood; Milani, Armin Ebrahimi

    2011-06-01

    The aim of this paper is to make a novel method for calculating the investment cost of Transmission services. It should be noted that some considerations such as used capacity, profits of reliability and profits of decreasing congestion-the money allocated to transmission services- are also taken into account. The proposed method is tested on an 8 bus test system. All simulations are done in MATLAB environment, and MATPOWER is used for Power Flow Analysis. In order to verify the proposed method, the optimal results are compared with the pervious techniques. Therefore, the proposed technique in the paper has important effects on investment on transmission network by improving the profits of reliability and decreasing congestion. Furthermore, simulations show that increasing maximum acceptable level of current will decrease the profit of decreasing congestion.

  11. Self-adapting network topologies in congested scenarios.

    PubMed

    Cholvi, Vicent; Laderas, Víctor; López, Luis; Fernández, Antonio

    2005-03-01

    Most studies in complex networks assume that once a link is created between two nodes it is never deleted. However, there is a recent interest towards systems where links can be rapidly rewired. An important issue in that type of networks is to discover the topology that, given a search algorithm, optimizes the search process. In this paper, we present a system model that, depending on the current network congestion, makes nodes to establish link connections so that the resulting topologies tend to a starlike topology when congestion is small and to randomlike topologies when congestion becomes relevant. Those topologies have been shown to be optimal in the above-mentioned conditions. Such a model can be easily implemented in practice and therefore, may be relevant in areas as the topology management of peer-to-peer networks.

  12. A Circuit Simulation Technique for Congested Network Traffic Assignment Problem

    NASA Astrophysics Data System (ADS)

    Cho, Hsun-Jung; Huang, Heng

    2007-12-01

    The relation between electrical circuit and traffic network has been proposed by Sasaki and Inouye, but they proposed link cost function is a linear function which cannot present the congestion situation. Cho and Huang extended the link cost function to a nonlinear function which can explain the congested network. In this paper, we proposed a foremost and novel approach to solve the traffic assignment problem (TAP) by simulating the electrical circuit network which consists of nonlinear link cost function models. Comparing with the solutions of Frank-Wolfe algorithm, the simulation results are nearly identical. Thus, the simulation of a network circuit model can be applied to solve network traffic assignment problems. Finally, two examples are proposed, and the results confirmed that electrical circuit simulation is workable in solving congested network traffic assignment problems.

  13. Significantly Elevated Liver Alkaline Phosphatase in Congestive Heart Failure

    PubMed Central

    Shamban, Leonid; Patel, Brijesh; Williams, Michael

    2014-01-01

    Congestive hepatopathy can have a mildly elevated liver profile, which should normalize with appropriate therapy. Liver specific alkaline phosphatase (ALP) in decompensated heart failure (HF) can be mildly elevated. The levels exceeding beyond the expected rise should be a concern and lead to further investigation. The literature reports insubstantial number of cases regarding significantly elevated levels of ALP and congestive hepatopathy. We report a case of a 45-year-old female with known history of severe cardiomyopathy that had persistently elevated levels of ALP. The extensive workup was negative for any specific pathology. The liver biopsy was consistent with congestive hepatopathy. The patient’s ALP levels decreased with aggressive diuretic therapy but still remained elevated. PMID:27785272

  14. [Erythropoiesis-stimulating agents in congestive heart failure patients].

    PubMed

    Robles Perez-Monteoliva, Nicolás Roberto; Macías Núñez, Juan Francisco; Herrera Pérez de Villar, Julio

    2014-03-04

    Congestive heart failure is a disease of high incidence and prevalence in the elderly. Anemia is associated with an increased mortality in these patients. This article reviews the cumulated evidence about the use of erythropoiesis-stimulating agents in congestive heart failure patients. Although some improvement in quality of life has been shown, it has not been found any decrement on mortality and, as a result, together with the high drug cost, it is not recommended the use of this kind of drugs in heart failure patients.

  15. Towards Microeconomic Resource Sharing in End System Multicast Networks Based on Walrasian General Equilibrium

    NASA Astrophysics Data System (ADS)

    Rezvani, Mohammad Hossein; Analoui, Morteza

    2010-11-01

    We have designed a competitive economical mechanism for application level multicast in which a number of independent services are provided to the end-users by a number of origin servers. Each offered service can be thought of as a commodity and the origin servers and the users who relay the service to their downstream nodes can thus be thought of as producers of the economy. Also, the end-users can be viewed as consumers of the economy. The proposed mechanism regulates the price of each service in such a way that general equilibrium holds. So, all allocations will be Pareto optimal in the sense that the social welfare of the users is maximized.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. An approach to verification and validation of a reliable multicasting protocol

    NASA Technical Reports Server (NTRS)

    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. 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 was different between the model and implementation, then the differences helped identify inconsistencies between the model and implementation. The dialogue between both teams drove the co-evolution of the model and implementation. Testing served as the vehicle for keeping the model and implementation in fidelity with each other. This paper describes (1) our experiences in developing our process model; and (2) three example problems found during the development of RMP.

  19. An Approach to Verification and Validation of a Reliable Multicasting Protocol

    NASA Technical Reports Server (NTRS)

    Callahan, John R.; Montgomery, Todd L.

    1994-01-01

    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. 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 offnominal behaviors predicted by the current model. If the execution of a test was different between the model and implementation, then the differences helped identify inconsistencies between the model and implementation. The dialogue between both teams drove the co-evolution of the model and implementation. Testing served as the vehicle for keeping the model and implementation in fidelity with each other. This paper describes (1) our experiences in developing our process model; and (2) three example problems found during the development of RMP.

  20. Pneumoconiosis increases the risk of congestive heart failure

    PubMed Central

    Yen, Chia-Ming; Lin, Cheng-Li; Lin, Ming-Chia; Chen, Huei-Yong; Lu, Nan-Han; Kao, Chia-Hung

    2016-01-01

    Abstract The purpose of the study was to determine the relationship between pneumoconiosis and congestive heart failure (CHF). We collected data from the National Health Insurance Research Database in Taiwan. The study sample comprised 8923 patients with pneumoconiosis and 35,692 nonpneumoconiosis controls enrolled from 2000 to 2011. Patients were followed up until the end of 2011 to evaluate the incidence of CHF. The risk of CHF was analyzed using Cox proportional hazard regression models, and the analysis accounted for factors such as sex, age, comorbidities, and air pollutants (μg/m3). The overall incidence of CHF was higher in the pneumoconiosis cohort (15.7 per 1000 person-y) than in the nonpneumoconiosis cohort (11.2 per 1000 person-y), with a crude hazard ratio (HR) of 1.40 (P < 0.001). The HR for CHF was 1.38-fold greater in the pneumoconiosis cohort than in the nonpneumoconiosis cohort (P < 0.001) after the model was adjusted for age, sex, various comorbidities, and air pollutants (μg/m3). The relative risk for CHF in the sex-specific pneumoconiosis cohort compared with the nonpneumoconiosis cohort was significant for men (adjusted HR = 1.40, 95% confidence interval = 1.21–1.62, P < 0.001). The incidence density rates of CHF increased with age; pneumoconiosis patients had a higher relative risk of CHF for all age group. Patients with pneumoconiosis were at higher risk for developing CHF than patients in the nonpneumoconiosis cohort, particularly in cases with coexisting coronary artery disease, hypertension, and chronic obstructive pulmonary disease. PMID:27336897

  1. Sodium and water balance in chronic congestive heart failure.

    PubMed Central

    Cody, R J; Covit, A B; Schaer, G L; Laragh, J H; Sealey, J E; Feldschuh, J

    1986-01-01

    As the characteristics of sodium and water balance in heart failure remain undefined, we evaluated the hemodynamic, metabolic, and hormonal effects of balanced sodium intake in 10 patients with chronic congestive heart failure. We discontinued diuretics to avoid their confounding influence, and all patients received 1 wk of 10 meq and 100 meq balanced sodium intake and controlled free water. Comparing sodium intake of 10 with 100 meq, the following observations were made. There was weight gain (2.0 kg) and increased sodium excretion (11 +/- 3 to 63 +/- 15 meq/24 h), unaccompanied by increase of blood volume. Both renin-angiotensin system and sympathetic nervous system activity were greater during the 10 meq diet, and suppressed with the 100 meq sodium diet. For both diets, plasma renin and urinary aldosterone excretion were correlated with urinary sodium excretion (r = -0.768, r = -0.726, respectively; P less than 0.005). Systemic hemodynamics were minimally changed with increased sodium intake. However, reversal of vasoconstriction by captopril during the 10 meq diet, and its ineffectiveness during the 100 meq diet, indicated a renin-dependent mechanism in the former, and a renin-independent mechanism in the latter diet. There were two subgroups of response to the 100 meq diet: one group (n = 5) achieved neutral balance, while the second (n = 5) avidly retained sodium and water. Renin-angiotensin system activity was significantly higher in the latter group, and the mechanism for differences in sodium excretion for the subgroups could not be identified by blood volume or hemodynamic parameters. Orthostatic hypotension during tilt was greater during the 10 meq sodium diet, and in all cases, related to ineffective hemodynamic and hormonal compensatory responses. PMID:3517066

  2. Increasing Intelligence in Inter-Vehicle Communications to Reduce Traffic Congestions: Experiments in Urban and Highway Environments

    PubMed Central

    Filho, Geraldo P. R.; Guidoni, Daniel L.; Pessin, Gustavo; Villas, Leandro A.; Ueyama, Jó

    2016-01-01

    Intelligent Transportation Systems (ITS) rely on Inter-Vehicle Communication (IVC) to streamline the operation of vehicles by managing vehicle traffic, assisting drivers with safety and sharing information, as well as providing appropriate services for passengers. Traffic congestion is an urban mobility problem, which causes stress to drivers and economic losses. In this context, this work proposes a solution for the detection, dissemination and control of congested roads based on inter-vehicle communication, called INCIDEnT. The main goal of the proposed solution is to reduce the average trip time, CO emissions and fuel consumption by allowing motorists to avoid congested roads. The simulation results show that our proposed solution leads to short delays and a low overhead. Moreover, it is efficient with regard to the coverage of the event and the distance to which the information can be propagated. The findings of the investigation show that the proposed solution leads to (i) high hit rate in the classification of the level of congestion, (ii) a reduction in average trip time, (iii) a reduction in fuel consumption, and (iv) reduced CO emissions PMID:27526048

  3. Increasing Intelligence in Inter-Vehicle Communications to Reduce Traffic Congestions: Experiments in Urban and Highway Environments.

    PubMed

    Meneguette, Rodolfo I; Filho, Geraldo P R; Guidoni, Daniel L; Pessin, Gustavo; Villas, Leandro A; Ueyama, Jó

    2016-01-01

    Intelligent Transportation Systems (ITS) rely on Inter-Vehicle Communication (IVC) to streamline the operation of vehicles by managing vehicle traffic, assisting drivers with safety and sharing information, as well as providing appropriate services for passengers. Traffic congestion is an urban mobility problem, which causes stress to drivers and economic losses. In this context, this work proposes a solution for the detection, dissemination and control of congested roads based on inter-vehicle communication, called INCIDEnT. The main goal of the proposed solution is to reduce the average trip time, CO emissions and fuel consumption by allowing motorists to avoid congested roads. The simulation results show that our proposed solution leads to short delays and a low overhead. Moreover, it is efficient with regard to the coverage of the event and the distance to which the information can be propagated. The findings of the investigation show that the proposed solution leads to (i) high hit rate in the classification of the level of congestion, (ii) a reduction in average trip time, (iii) a reduction in fuel consumption, and (iv) reduced CO emissions.

  4. Understanding congestion in China's medical market: an incentive structure perspective.

    PubMed

    Sun, Zesheng; Wang, Shuhong; Barnes, Stephen R

    2016-04-01

    Congestion has become one of the most important factors leading to patient dissatisfaction and doctor-patient conflicts in the medical market of China. In this study, we explore the causes and effects of structural congestion in the Chinese medical market from an incentive structure perspective. Our analysis reveals that prior medical system reforms with price regulation in China have induced hospitals to establish incentives for capital-intensive investments, while ignoring human capital, and have driven medical staff and patients to higher-level hospitals, reinforcing an incentive structure in which congestion in higher-level hospitals and idle resources in lower-level hospitals coexist. The existing incentive structure has led to cost increases and degradation of human capital and specific factor effects. Recent reforms to reduce congestion in the Chinese medical market were not effective. Most of them had no impact on and did not involve the existing distorted incentive structure. Future reforms should consider rebalancing expectations for medical quality, free flow of human capital and price regulation reforms to rebuild a new incentive structure.

  5. Teaching Congestive Heart Failure to Doctor of Pharmacy Students.

    ERIC Educational Resources Information Center

    Parker, Robert B.

    1992-01-01

    This paper summarizes a lecture given to pharmacy students that emphasizes the pathophysiologic mechanisms causing congestive heart failure and the effects of drugs on these mechanisms. The approach shows the importance of drug therapy in this disorder and how this knowledge can improve patient care. An appendix provides a case study. (GLR)

  6. A survey of ring-building network protocols suitable for command and control group communications

    NASA Astrophysics Data System (ADS)

    Sobeih, Ahmed; Yurcik, William

    2005-05-01

    Multicasting is the enabling technology for group communication. However, network-layer multicasting (e.g., IP multicast) has not been widely adopted more than 10 years of its invention due to the concerns related to deployment, scalability and network management. Application-layer multicast (ALM) has been proposed as an alternative for IP multicast. In ALM, group communications take place on an overlay network in which each edge corresponds to a direct unicast path between two group members. ALM protocols differ in, among other aspects, the topology of the underlying overlay network (e.g., tree, mesh or ring). Ring-based ALM protocols have the advantages of providing a constant node degree, and enabling the implementation of reliable and totally-ordered message delivery through the use of a ring with a token that contains ordering and flow control information. In addition, a ring overlay network topology is inherently reliable to single node failures. In this paper, we provide a survey and a taxonomy of several ring-building group communication protocols. Investigating the major characteristics of ring-building network protocols is an important step towards understanding which of them are suitable for command and control group communications.

  7. A perspective on sympathetic renal denervation in chronic congestive heart failure.

    PubMed

    Madanieh, Raef; El-Hunjul, Mohammed; Alkhawam, Hassan; Kosmas, Constantine E; Madanieh, Abed; Vittorio, Timothy J

    2016-01-01

    Medical therapy has indisputably been the mainstay of management for chronic congestive heart failure. However, a significant percentage of patients continue to experience worsening heart failure (HF) symptoms despite treatment with multiple therapeutic agents. Recently, catheter-based interventional strategies that interrupt the renal sympathetic nervous system have shown promising results in providing better symptom control in patients with HF. In this article, we will review the pathophysiology of HF for better understanding of the interplay between the cardiovascular system and the kidney. Subsequently, we will briefly discuss pivotal renal denervation (RDN) therapy trials in patients with resistant hypertension and then present the available evidence on the role of RDN in HF therapy.

  8. 23 CFR 970.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Federal lands congestion management system (CMS). 970....214 Federal lands congestion management system (CMS). (a) For purposes of this section, congestion...) Develop criteria to determine when a CMS is to be implemented for a specific transportation system; and...

  9. 23 CFR 972.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Federal lands congestion management system (CMS). 972... § 972.214 Federal lands congestion management system (CMS). (a) For purposes of this section, congestion... interference. For those FWS transportation systems that require a CMS, in both metropolitan and...

  10. 23 CFR 971.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Federal lands congestion management system (CMS). 971... Federal lands congestion management system (CMS). (a) For purposes of this section, congestion means the...) Develop criteria to determine when a CMS is to be implemented for a specific FH; and (2) Have CMS...

  11. 23 CFR 972.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Federal lands congestion management system (CMS). 972... § 972.214 Federal lands congestion management system (CMS). (a) For purposes of this section, congestion... interference. For those FWS transportation systems that require a CMS, in both metropolitan and...

  12. 23 CFR 971.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Federal lands congestion management system (CMS). 971... Federal lands congestion management system (CMS). (a) For purposes of this section, congestion means the...) Develop criteria to determine when a CMS is to be implemented for a specific FH; and (2) Have CMS...

  13. 23 CFR 971.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Federal lands congestion management system (CMS). 971... Federal lands congestion management system (CMS). (a) For purposes of this section, congestion means the...) Develop criteria to determine when a CMS is to be implemented for a specific FH; and (2) Have CMS...

  14. 23 CFR 972.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Federal lands congestion management system (CMS). 972... § 972.214 Federal lands congestion management system (CMS). (a) For purposes of this section, congestion... interference. For those FWS transportation systems that require a CMS, in both metropolitan and...

  15. 23 CFR 972.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Federal lands congestion management system (CMS). 972... § 972.214 Federal lands congestion management system (CMS). (a) For purposes of this section, congestion... interference. For those FWS transportation systems that require a CMS, in both metropolitan and...

  16. 23 CFR 970.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Federal lands congestion management system (CMS). 970....214 Federal lands congestion management system (CMS). (a) For purposes of this section, congestion...) Develop criteria to determine when a CMS is to be implemented for a specific transportation system; and...

  17. 23 CFR 971.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Federal lands congestion management system (CMS). 971... Federal lands congestion management system (CMS). (a) For purposes of this section, congestion means the...) Develop criteria to determine when a CMS is to be implemented for a specific FH; and (2) Have CMS...

  18. 23 CFR 971.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Federal lands congestion management system (CMS). 971... LANDS HIGHWAYS FOREST SERVICE MANAGEMENT SYSTEMS Forest Highway Program Management Systems § 971.214 Federal lands congestion management system (CMS). (a) For purposes of this section, congestion means...

  19. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Congestion management process in transportation... Programming § 450.320 Congestion management process in transportation management areas. (a) The transportation planning process in a TMA shall address congestion management through a process that provides for safe...

  20. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Congestion management process in transportation... Programming § 450.320 Congestion management process in transportation management areas. (a) The transportation planning process in a TMA shall address congestion management through a process that provides for safe...

  1. Extracorporeal versus peritoneal ultrafiltration in diuretic-resistant congestive heart failure – a review

    PubMed Central

    Wańkowicz, Zofia; Próchnicka, Agnieszka; Olszowska, Anna; Baczyński, Daniel; Krzesiński, Paweł; Dziuk, Mirosław

    2011-01-01

    Summary Diuretic-resistant congestive heart failure in the form of type 2 cardiorenal syndrome is a problem of growing significance in everyday clinical practice because of high morbidity and mortality. There has been scant progress in the treatment of overhydration, the main cause of symptoms in this group of patients. The aim of our review is to present recent advances in the ultrafiltration therapy of congestive heart failure, with special attention to the new dedicated device for extracorporeal isolated ultrafiltration, as well as modifications of peritoneal dialysis in the form of peritoneal ultrafiltration with icodextrin solution and incremental peritoneal dialysis. Technical and clinical features, costs and potential risks of available devices for isolated ultrafiltration are presented. This method should be reserved for patients with true diuretic resistance as part of a more complex strategy aiming at the adequate control of fluid retention. Peritoneal ultrafiltration is presented as a viable alternative to extracorporeal ultrafiltration because of medical and psychosocial benefits of home-based therapy, lower costs and more effective daily ultrafiltration. In conclusion, large, properly randomized and controlled clinical trials with long-term follow-up will be essential in assessing the logistics and cost-effectiveness of both methods. Most importantly, however, they should be able to evaluate the impact of both methods on preservation of renal function and delaying the progression of heart failure by interrupting the vicious circle of cardiorenal syndrome. Our review is supplemented with the case report of the use of peritoneal ultrafiltration with a single 12-hour nighttime icodextrin exchange as a life-saving procedure in a patient with congestive heart failure resistant to pharmacological treatment. PMID:22129914

  2. Extracorporeal versus peritoneal ultrafiltration in diuretic-resistant congestive heart failure--a review.

    PubMed

    Wańkowicz, Zofia; Próchnicka, Agnieszka; Olszowska, Anna; Baczyński, Daniel; Krzesiński, Paweł; Dziuk, Mirosław

    2011-12-01

    Diuretic-resistant congestive heart failure in the form of type 2 cardiorenal syndrome is a problem of growing significance in everyday clinical practice because of high morbidity and mortality. There has been scant progress in the treatment of overhydration, the main cause of symptoms in this group of patients. The aim of our review is to present recent advances in the ultrafiltration therapy of congestive heart failure, with special attention to the new dedicated device for extracorporeal isolated ultrafiltration, as well as modifications of peritoneal dialysis in the form of peritoneal ultrafiltration with icodextrin solution and incremental peritoneal dialysis. Technical and clinical features, costs and potential risks of available devices for isolated ultrafiltration are presented. This method should be reserved for patients with true diuretic resistance as part of a more complex strategy aiming at the adequate control of fluid retention. Peritoneal ultrafiltration is presented as a viable alternative to extracorporeal ultrafiltration because of medical and psychosocial benefits of home-based therapy, lower costs and more effective daily ultrafiltration. In conclusion, large, properly randomized and controlled clinical trials with long-term follow-up will be essential in assessing the logistics and cost-effectiveness of both methods. Most importantly, however, they should be able to evaluate the impact of both methods on preservation of renal function and delaying the progression of heart failure by interrupting the vicious circle of cardiorenal syndrome. Our review is supplemented with the case report of the use of peritoneal ultrafiltration with a single 12-hour nighttime icodextrin exchange as a life-saving procedure in a patient with congestive heart failure resistant to pharmacological treatment.

  3. Peripheral venous congestion causes time- and dose-dependent release of endothelin-1 in humans.

    PubMed

    Lin, Jeffrey; Chudasama, Neelesh; Hayashi, Yacki; Hawk, Christopher; Ramnauth, Sahadeo D; Wong, Ka Yuk; Harxhi, Ante; Onat, Duygu; Wakabayashi, Michiyori; Uriel, Nir; Jorde, Ulrich P; LeJemtel, Thierry H; Sabbah, Hani N; Demmer, Ryan T; Colombo, Paolo C

    2017-03-01

    Endothelin-1 (ET-1) is a pivotal mediator of vasoconstriction and inflammation in congestive states such as heart failure (HF) and chronic kidney disease (CKD). Whether peripheral venous congestion (VC) increases plasma ET-1 at pressures commonly seen in HF and CKD patients is unknown. We seek to characterize whether peripheral VC promotes time- and dose-dependent increases in plasma ET-1 and whether these changes are sustained after decongestion. We used a randomized, cross-over design in 20 healthy subjects (age 30 ± 7 years). To experimentally model VC, venous pressure was increased to either 15 or 30 mmHg (randomized at first visit) above baseline by inflating a cuff around the subject's dominant arm; the nondominant arm served as a noncongested control. We measured plasma ET-1 at baseline, after 20, 60 and 120 min of VC, and finally at 180 min (60 min after cuff release and decongestion). Plasma ET-1 progressively and significantly increased over 120 min in the congested arm relative to the control arm and to baseline values. This effect was dose-dependent: ET-1 increased by 45% and 100% at VC doses of 15 and 30 mmHg, respectively (P < 0.05), and declined after 60 min of decongestion though remaining significantly elevated compared to baseline. In summary, peripheral VC causes time- and dose-dependent increases in plasma ET-1. Of note, the lower dose of 15 mmHg (more clinically relevant to HF and CKD patients) was sufficient to raise ET-1. These findings support the potentially contributory, not merely consequential, role of VC in the pathophysiology of HF and CKD.

  4. Congestion Avoidance Testbed Experiments. Volume 2

    NASA Technical Reports Server (NTRS)

    Denny, Barbara A.; Lee, Diane S.; McKenney, Paul E., Sr.; Lee, Danny

    1994-01-01

    DARTnet provides an excellent environment for executing networking experiments. Since the network is private and spans the continental United States, it gives researchers a great opportunity to test network behavior under controlled conditions. However, this opportunity is not available very often, and therefore a support environment for such testing is lacking. To help remedy this situation, part of SRI's effort in this project was devoted to advancing the state of the art in the techniques used for benchmarking network performance. The second objective of SRI's effort in this project was to advance networking technology in the area of traffic control, and to test our ideas on DARTnet, using the tools we developed to improve benchmarking networks. Networks are becoming more common and are being used by more and more people. The applications, such as multimedia conferencing and distributed simulations, are also placing greater demand on the resources the networks provide. Hence, new mechanisms for traffic control must be created to enable their networks to serve the needs of their users. SRI's objective, therefore, was to investigate a new queueing and scheduling approach that will help to meet the needs of a large, diverse user population in a "fair" way.

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

    NASA Technical Reports Server (NTRS)

    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

  6. How congestion shapes cities: from mobility patterns to scaling

    PubMed Central

    Louf, Rémi; Barthelemy, Marc

    2014-01-01

    The recent availability of data for cities has allowed scientists to exhibit scalings which present themselves in the form of a power-law dependence on population of various socio-economical and structural indicators. We propose here a stochastic theory of urban growth which accounts for some of the observed scalings and we confirm these predictions on US and OECD empirical data. In particular, we show that the dependence on population size of the total number of miles driven daily, the total length of the road network, the total traffic delay, the total consumption of gasoline, the quantity of CO2 emitted and the relation between area and population of cities, are all governed by a single parameter which characterizes the sensitivity to congestion. Our results suggest that diseconomies associated with congestion scale superlinearly with population size, implying that –despite polycentrism– cities whose transportation infrastructure rely heavily on traffic sensitive modes are unsustainable. PMID:24990624

  7. How congestion shapes cities: from mobility patterns to scaling.

    PubMed

    Louf, Rémi; Barthelemy, Marc

    2014-07-03

    The recent availability of data for cities has allowed scientists to exhibit scalings which present themselves in the form of a power-law dependence on population of various socio-economical and structural indicators. We propose here a stochastic theory of urban growth which accounts for some of the observed scalings and we confirm these predictions on US and OECD empirical data. In particular, we show that the dependence on population size of the total number of miles driven daily, the total length of the road network, the total traffic delay, the total consumption of gasoline, the quantity of CO2 emitted and the relation between area and population of cities, are all governed by a single parameter which characterizes the sensitivity to congestion. Our results suggest that diseconomies associated with congestion scale superlinearly with population size, implying that -despite polycentrism- cities whose transportation infrastructure rely heavily on traffic sensitive modes are unsustainable.

  8. Iodine-123 metaiodobenzylguanidine imaging of the heart in idiopathic congestive cardiomyopathy and cardiac transplants

    SciTech Connect

    Glowniak, J.V.; Turner, F.E.; Gray, L.L.; Palac, R.T.; Lagunas-Solar, M.C.; Woodward, W.R.

    1989-07-01

    Iodine-123 metaiodobenzylguanidine ((/sup 123/I)MIBG) is a norepinephrine analog which can be used to image the sympathetic innervation of the heart. In this study, cardiac imaging with (/sup 123/I)MIBG was performed in patients with idiopathic congestive cardiomyopathy and compared to normal controls. Initial uptake, half-time of tracer within the heart, and heart to lung ratios were all significantly reduced in patients compared to normals. Uptake in lungs, liver, salivary glands, and spleen was similar in controls and patients with cardiomyopathy indicating that decreased MIBG uptake was not a generalized abnormality in these patients. Iodine-123 MIBG imaging was also performed in cardiac transplant patients to determine cardiac nonneuronal uptake. Uptake in transplants was less than 10% of normals in the first 2 hr and nearly undetectable after 16 hr. The decreased uptake of MIBG suggests cardiac sympathetic nerve dysfunction while the rapid washout of MIBG from the heart suggests increased cardiac sympathetic nerve activity in idiopathic congestive cardiomyopathy.

  9. Multifunctional switching unit for add/drop, wavelength conversion, format conversion, and WDM multicast based on bidirectional LCoS and SOA-loop architecture.

    PubMed

    Wang, Danshi; Zhang, Min; Qin, Jun; Lu, Guo-Wei; Wang, Hongxiang; Huang, Shanguo

    2014-09-08

    We propose a multifunctional optical switching unit based on the bidirectional liquid crystal on silicon (LCoS) and semiconductor optical amplifier (SOA) architecture. Add/drop, wavelength conversion, format conversion, and WDM multicast are experimentally demonstrated. Due to the bidirectional characteristic, the LCoS device cannot only multiplex the input signals, but also de-multiplex the converted signals. Dual-channel wavelength conversion and format conversion from 2 × 25Gbps differential quadrature phase-shift-keying (DQPSK) to 2 × 12.5Gbps differential phase-shift-keying (DPSK) based on four-wave mixing (FWM) in SOA is obtained with only one pump. One-to-six WDM multicast of 25Gbps DQPSK signals with two pumps is also achieved. All of the multicast channels are with a power penalty less than 1.1 dB at FEC threshold of 3.8 × 10⁻³.

  10. Optimal Use of Beta-Blockers for Congestive Heart Failure.

    PubMed

    Lee, Hae-Young; Baek, Sang Hong

    2016-01-01

    Beta-blockers are the cornerstone treatment for congestive heart failure (HF). Current HF guidelines commonly recommend β-blockers for the treatment of HF with reduced left ventricular ejection fraction (LVEF). The effect of β-blockers, however, is less clear for HF patients with preserved LVEF, unstable severe acute HF, or right ventricular failure. This review summarizes the effect of β-blockers in various clinical situations and suggests a strategy for optimal use. (Circ J 2016; 80: 565-571).

  11. Load Distribution in Congested Scale-Free Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jian-Feng; Gao, Zi-You; Fu, Bai-Bai

    In this work, we study the effects of scale-free topology and congestion on load distribution. Congestion effect can be described by link cost functions, which map link flows into travel times. Two different kinds of link's practical capacity (it is similar to link's capacity for transport) which is a parameter in link cost functions, i.e., uniform case and nonuniform case, are investigated. After introducing the effect of congestion, load distribution is typically discussed in Barábasi-Albert and Goh scale-free networks. In the uniform case, for Barábasi-Albert scale-free networks, we recover a power-law behavior for load distribution with a larger exponent, as compared with the distribution of betweenness centrality; for Goh scale-free networks, we also recover a power-law behavior and its exponent approaches to the exponent of degree distribution. While in the nonuniform case, the power-law behavior for load distribution may not always be conserved in both Barábasi-Albert and Goh scale-free networks. That is to say, different kinds of load distributions are obtained under different conditions. It may shed some light to study traffic dynamics on scale-free networks.

  12. Predictability of Road Traffic and Congestion in Urban Areas

    PubMed Central

    Wang, Jingyuan; Mao, Yu; Li, Jing; Xiong, Zhang; Wang, Wen-Xu

    2015-01-01

    Mitigating traffic congestion on urban roads, with paramount importance in urban development and reduction of energy consumption and air pollution, depends on our ability to foresee road usage and traffic conditions pertaining to the collective behavior of drivers, raising a significant question: to what degree is road traffic predictable in urban areas? Here we rely on the precise records of daily vehicle mobility based on GPS positioning device installed in taxis to uncover the potential daily predictability of urban traffic patterns. Using the mapping from the degree of congestion on roads into a time series of symbols and measuring its entropy, we find a relatively high daily predictability of traffic conditions despite the absence of any priori knowledge of drivers' origins and destinations and quite different travel patterns between weekdays and weekends. Moreover, we find a counterintuitive dependence of the predictability on travel speed: the road segment associated with intermediate average travel speed is most difficult to be predicted. We also explore the possibility of recovering the traffic condition of an inaccessible segment from its adjacent segments with respect to limited observability. The highly predictable traffic patterns in spite of the heterogeneity of drivers' behaviors and the variability of their origins and destinations enables development of accurate predictive models for eventually devising practical strategies to mitigate urban road congestion. PMID:25849534

  13. Traffic Congestion Detection System through Connected Vehicles and Big Data

    PubMed Central

    Cárdenas-Benítez, Néstor; Aquino-Santos, Raúl; Magaña-Espinoza, Pedro; Aguilar-Velazco, José; Edwards-Block, Arthur; Medina Cass, Aldo

    2016-01-01

    This article discusses the simulation and evaluation of a traffic congestion detection system which combines inter-vehicular communications, fixed roadside infrastructure and infrastructure-to-infrastructure connectivity and big data. The system discussed in this article permits drivers to identify traffic congestion and change their routes accordingly, thus reducing the total emissions of CO2 and decreasing travel time. This system monitors, processes and stores large amounts of data, which can detect traffic congestion in a precise way by means of a series of algorithms that reduces localized vehicular emission by rerouting vehicles. To simulate and evaluate the proposed system, a big data cluster was developed based on Cassandra, which was used in tandem with the OMNeT++ discreet event network simulator, coupled with the SUMO (Simulation of Urban MObility) traffic simulator and the Veins vehicular network framework. The results validate the efficiency of the traffic detection system and its positive impact in detecting, reporting and rerouting traffic when traffic events occur. PMID:27136548

  14. Predictability of road traffic and congestion in urban areas.

    PubMed

    Wang, Jingyuan; Mao, Yu; Li, Jing; Xiong, Zhang; Wang, Wen-Xu

    2015-01-01

    Mitigating traffic congestion on urban roads, with paramount importance in urban development and reduction of energy consumption and air pollution, depends on our ability to foresee road usage and traffic conditions pertaining to the collective behavior of drivers, raising a significant question: to what degree is road traffic predictable in urban areas? Here we rely on the precise records of daily vehicle mobility based on GPS positioning device installed in taxis to uncover the potential daily predictability of urban traffic patterns. Using the mapping from the degree of congestion on roads into a time series of symbols and measuring its entropy, we find a relatively high daily predictability of traffic conditions despite the absence of any priori knowledge of drivers' origins and destinations and quite different travel patterns between weekdays and weekends. Moreover, we find a counterintuitive dependence of the predictability on travel speed: the road segment associated with intermediate average travel speed is most difficult to be predicted. We also explore the possibility of recovering the traffic condition of an inaccessible segment from its adjacent segments with respect to limited observability. The highly predictable traffic patterns in spite of the heterogeneity of drivers' behaviors and the variability of their origins and destinations enables development of accurate predictive models for eventually devising practical strategies to mitigate urban road congestion.

  15. All-optical wavelength conversion and five-channel multicasting for 20 Gbit/s QPSK signals in a silicon waveguide.

    PubMed

    Wang, Xiaoyan; Huang, Lingchen; Yi, Ke; Feng, Xianglian; Gao, Shiming

    2014-11-01

    Wavelength conversion and five-channel multicasting for 20  Gbit/s quadrature phase-shift keying signals have been experimentally demonstrated based on four-wave mixing in a silicon waveguide with digital coherent detection. The eye diagrams and constellation diagrams of the converted and multicasting idlers are successfully observed. Moreover, the bit-error rates (BERs) of the generated idlers are measured and the power penalties are all less than 0.7 dB at a BER of 3×10(-3).

  16. Analysis of safety factors for urban expressways considering the effect of congestion in Shanghai, China.

    PubMed

    Sun, Jian; Li, Tienan; Li, Feng; Chen, Feng

    2016-10-01

    Urban expressways are the key components of the urban traffic network. The traffic safety situation on expressways directly influences the efficiency of the whole network. A total of 48,325 crashes were recorded by Shanghai Expressway Surveillance System in a three-year period. Considering the different crash mechanisms under different congestion levels, models for the total crashes, non-congested-flow crashes and congested-flow crashes were respectively formulated based on the real-time traffic condition corresponding to each crash. Moreover, considering the potential spatial correlation among segments, the adjacent-correlated spatial and distance-correlated spatial models were formulated and compared to the traditional non-spatial-correlated model. A Bayesian approach was employed to estimate the parameters. The results showed that the congestion index, merging ratio, ramp density, and average daily traffic significantly affect the crash frequency. The safety factors in non-congested flow and congested flow are different; diverging behavior is more risky in non-congested flow, more lanes tend to increase the risk of crashes in congested flow, and horizontal curves tend to decrease the crash risk in congested flow but cause high risk in non-congested flow. In addition, the distance-correlated spatial model is found to be the best-fitting model. The results of this study suggested that dedicated safety countermeasures can be designed for different traffic situations on urban expressways.

  17. Congestion Prediction Modeling for Quality of Service Improvement in Wireless Sensor Networks

    PubMed Central

    Lee, Ga-Won; Lee, Sung-Young; Huh, Eui-Nam

    2014-01-01

    Information technology (IT) is pushing ahead with drastic reforms of modern life for improvement of human welfare. Objects constitute “Information Networks” through smart, self-regulated information gathering that also recognizes and controls current information states in Wireless Sensor Networks (WSNs). Information observed from sensor networks in real-time is used to increase quality of life (QoL) in various industries and daily life. One of the key challenges of the WSNs is how to achieve lossless data transmission. Although nowadays sensor nodes have enhanced capacities, it is hard to assure lossless and reliable end-to-end data transmission in WSNs due to the unstable wireless links and low hard ware resources to satisfy high quality of service (QoS) requirements. We propose a node and path traffic prediction model to predict and minimize the congestion. This solution includes prediction of packet generation due to network congestion from both periodic and event data generation. Simulation using NS-2 and Matlab is used to demonstrate the effectiveness of the proposed solution. PMID:24784035

  18. Design and Implementation of Real-Time Vehicular Camera for Driver Assistance and Traffic Congestion Estimation

    PubMed Central

    Son, Sanghyun; Baek, Yunju

    2015-01-01

    As society has developed, the number of vehicles has increased and road conditions have become complicated, increasing the risk of crashes. Therefore, a service that provides safe vehicle control and various types of information to the driver is urgently needed. In this study, we designed and implemented a real-time traffic information system and a smart camera device for smart driver assistance systems. We selected a commercial device for the smart driver assistance systems, and applied a computer vision algorithm to perform image recognition. For application to the dynamic region of interest, dynamic frame skip methods were implemented to perform parallel processing in order to enable real-time operation. In addition, we designed and implemented a model to estimate congestion by analyzing traffic information. The performance of the proposed method was evaluated using images of a real road environment. We found that the processing time improved by 15.4 times when all the proposed methods were applied in the application. Further, we found experimentally that there was little or no change in the recognition accuracy when the proposed method was applied. Using the traffic congestion estimation model, we also found that the average error rate of the proposed model was 5.3%. PMID:26295230

  19. Congestion prediction modeling for quality of service improvement in wireless sensor networks.

    PubMed

    Lee, Ga-Won; Lee, Sung-Young; Huh, Eui-Nam

    2014-04-30

    Information technology (IT) is pushing ahead with drastic reforms of modern life for improvement of human welfare. Objects constitute "Information Networks" through smart, self-regulated information gathering that also recognizes and controls current information states in Wireless Sensor Networks (WSNs). Information observed from sensor networks in real-time is used to increase quality of life (QoL) in various industries and daily life. One of the key challenges of the WSNs is how to achieve lossless data transmission. Although nowadays sensor nodes have enhanced capacities, it is hard to assure lossless and reliable end-to-end data transmission in WSNs due to the unstable wireless links and low hard ware resources to satisfy high quality of service (QoS) requirements. We propose a node and path traffic prediction model to predict and minimize the congestion. This solution includes prediction of packet generation due to network congestion from both periodic and event data generation. Simulation using NS-2 and Matlab is used to demonstrate the effectiveness of the proposed solution.

  20. Design and Implementation of Real-Time Vehicular Camera for Driver Assistance and Traffic Congestion Estimation.

    PubMed

    Son, Sanghyun; Baek, Yunju

    2015-08-18

    As society has developed, the number of vehicles has increased and road conditions have become complicated, increasing the risk of crashes. Therefore, a service that provides safe vehicle control and various types of information to the driver is urgently needed. In this study, we designed and implemented a real-time traffic information system and a smart camera device for smart driver assistance systems. We selected a commercial device for the smart driver assistance systems, and applied a computer vision algorithm to perform image recognition. For application to the dynamic region of interest, dynamic frame skip methods were implemented to perform parallel processing in order to enable real-time operation. In addition, we designed and implemented a model to estimate congestion by analyzing traffic information. The performance of the proposed method was evaluated using images of a real road environment. We found that the processing time improved by 15.4 times when all the proposed methods were applied in the application. Further, we found experimentally that there was little or no change in the recognition accuracy when the proposed method was applied. Using the traffic congestion estimation model, we also found that the average error rate of the proposed model was 5.3%.

  1. Relieving nasal congestion in children with seasonal and perennial allergic rhinitis: efficacy and safety studies of mometasone furoate nasal spray

    PubMed Central

    2013-01-01

    Background In surveys of children with allergic rhinitis (AR), nasal congestion has been identified as the most frequently experienced and bothersome symptom. This analysis was conducted to investigate the effect of mometasone furoate nasal spray (MFNS) on congestion in children with AR. Methods Two multicenter, double-blind, placebo-controlled studies randomly assigned children to MFNS 100 μg or placebo, 1 spray/nostril QD for 4 weeks (Study 1: ages 6–11 years with seasonal AR [SAR] ≥1 year; Study 2: ages 3–11 years with perennial AR [PAR] ≥1 year). Least square (LS) means were obtained from an ANCOVA model with treatment and study center effects, with baseline score as a covariate. We conducted post hoc evaluation of changes from baseline in AM/PM PRIOR (average of reflective AM and PM scores) nasal congestion (0=none to 3=severe). Results Study 1: MFNS (n=134) reduced congestion significantly more than placebo (n=135) on day 2 (P=.004) and on 23/29 days (P≤.037). Change from baseline was −0.53 and −0.28 for MFNS and placebo (P<.001) over days 1–15 and −0.64 and −0.38 for MFNS and placebo (P<.001) over days 1–29. Study 2: MFNS (n=185) reduced congestion significantly more than placebo (n=189) on day 3 (P=.015) and on 22/29 days (P≤.047). Change from baseline was −0.56 and −0.36 for MFNS and placebo (P<.001) over days 1–15 and −0.64 and −0.45 for MFNS and placebo (P<.001) over days 1–29. MFNS was well tolerated, with no unusual or unexpected adverse events. Conclusion MFNS effectively relieved nasal congestion and was well tolerated in children with SAR or PAR. PMID:23663488

  2. 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

    NASA Astrophysics Data System (ADS)

    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.

  3. Transmission dispatch and congestion management in open market systems

    NASA Astrophysics Data System (ADS)

    Fang, Risheng

    This thesis is located in the domain of electricity supply industry restructuring. It deals with emerging issues, whose understanding is essential to advancing knowledge of open access transmission theory and proceeds to develop approaches for solving the transmission dispatch and congestion management problem. An overview of current trends and experiences in utility restructuring and the main models for restructuring, as well as the classifications of system operators, is first presented. A fully unbundled competitive electricity market model, called the bilateral/multilateral trades model, is then developed. A survey of current research in transmission dispatch and congestion management is included with discussion of transmission capacity and ancillary services. A methodology for the power dispatch problem in a structure dominated by bilateral and multilateral transmission contracts is presented. Group structures are mathematically formulated and explored and three basic types of curtailment strategies proposed for use by market participants. A more complex model is then developed, which takes into account the co-existence of bilateral and multilateral contracts with pool type dynamic supplies and demands based on bids and market clearing prices. An integrated dispatch strategy to reconcile all three types of transactions (bilateral, multilateral and pool) is then developed. Prioritization of electricity transactions and related curtailment strategies are explored and a mechanism for coordination between market participants to achieve additional economic advantages is described. A theory of security based rescheduling is presented in order to investigate the security-related aspects of operation in an unbundled and deregulated system. The impact of post-contingency corrective capability on optimal rescheduling results has been identified and the advantage of incorporating post-contingency corrective rescheduling into the objective function demonstrated. Finally

  4. Pulmonary Congestion and Physical Functioning in Peritoneal Dialysis Patients

    PubMed Central

    Enia, Giuseppe; Tripepi, Rocco; Panuccio, Vincenzo; Torino, Claudia; Garozzo, Maurizio; Battaglia, Giovanni Giorgio; Zoccali, Carmine

    2012-01-01

    ♦ Purpose: Decline in physical function is commonly observed in patients with kidney failure on dialysis. Whether lung congestion, a predictable consequence of cardiomyopathy and fluid overload, may contribute to the low physical functioning of these patients has not been investigated. ♦ Methods: In 51 peritoneal dialysis (PD) patients, we investigated the cross-sectional association between the physical functioning scale of the Kidney Disease Quality of Life Short Form (KDQOL-SF: Rand Corporation, Santa Monica, CA, USA) and an ultrasonographic measure of lung water recently validated in dialysis patients. The relationship between physical functioning and lung water was also analyzed taking into account the severity of dyspnea measured using the New York Heart Association (NYHA) classification currently used to grade the severity of heart failure. ♦ Results: Evidence of moderate-to-severe lung congestion was evident in 20 patients, and this alteration was asymptomatic (that is, NHYHA class I) in 11 patients (55%). On univariate analysis, physical functioning was inversely associated with lung water (r = -0.48, p < 0.001), age (r = -0.44, p = 0.001), previous cardiovascular events (r = -0.46, p = 0.001), and fibrinogen (r = -0.34, p = 0.02). Physical functioning was directly associated with blood pressure, the strongest association being with diastolic blood pressure (r = 0.38, p = 0.006). The NYHA class correlated inversely with physical functioning (r = -0.51, p < 0.001). In multiple regression analysis, only lung water and fibrinogen remained independent correlates of physical functioning. The NYHA class failed to maintain its independent association. ♦ Conclusions: This cross-sectional study supports the hypothesis that symptomatic and asymptomatic lung congestion is a relevant factor in the poor physical functioning of patients on PD. PMID:22942271

  5. Effect of Congestion Costs on Shortest Paths Through Complex Networks

    NASA Astrophysics Data System (ADS)

    Ashton, Douglas J.; Jarrett, Timothy C.; Johnson, Neil F.

    2005-02-01

    We analyze analytically the effect of congestion costs within a physically relevant, yet exactly solvable, network model featuring central hubs. These costs lead to a competition between centralized and decentralized transport pathways. In stark contrast to conventional no-cost networks, there now exists an optimal number of connections to the central hub in order to minimize the shortest path. Our results shed light on an open problem in biology, informatics, and sociology, concerning the extent to which decentralized versus centralized design benefits real-world complex networks.

  6. Effect of congestion costs on shortest paths through complex networks.

    PubMed

    Ashton, Douglas J; Jarrett, Timothy C; Johnson, Neil F

    2005-02-11

    We analyze analytically the effect of congestion costs within a physically relevant, yet exactly solvable, network model featuring central hubs. These costs lead to a competition between centralized and decentralized transport pathways. In stark contrast to conventional no-cost networks, there now exists an optimal number of connections to the central hub in order to minimize the shortest path. Our results shed light on an open problem in biology, informatics, and sociology, concerning the extent to which decentralized versus centralized design benefits real-world complex networks.

  7. Cerebral Venous Congestion as Indication for Thrombolytic Treatment

    SciTech Connect

    Tsai, Fong Y. Kostanian, Varoujan; Rivera, Monica; Lee, Kwo-Whie; Chen, Clayton C.; Nguyen, Thong H.

    2007-07-15

    Purpose. To carry out a retrospective analysis of patients with acute dural sinus thrombosis, and the role of cerebral venous congestion in patient management. Methods. Twenty-five patients were identified with the clinical and imaging diagnosis of acute dural sinus thrombosis. The imaging diagnosis was by magnetic resonance (MR) and/or computed tomography (CT) venography. There was a female predominance with a female to male ratio of 1.5 to 1 (16 women, 9 men). The age range was from 19 to 64 years old with an average age of 37 years. The first 10 patients, who ranged in age from 21 to 64 years old (average 37 years), received only anticoagulation therapy with heparin and warfarin for periods ranging from 5 days to 2 months. The remaining 15 patients ranged in age from 19 to 57 years old (average 38 years). They either underwent subsequent thrombectomy after a trial of anticoagulation therapy, or went straight to thrombectomy. These latter 15 patients had initial evidence of cerebral venous congestion, either clinically by severe or worsening symptoms despite anticoagulation therapy, or on initial or subsequent CT or MR imaging. In our experience, the cerebral venous congestion imaging findings included intracranial hemorrhage, a hematoma, or edema. The thrombolytic treatment technique consisted of the advancement of a 6 Fr guiding catheter to the jugular bulb or sigmoid sinus from a transfemoral approach. A microcatheter was then advanced to the proximal portion of the thrombus and then either tissue plasminogen activator (tPA) or urokinase was injected to prevent clot propagation. A balloon catheter was used to perform thrombectomy since the thrombolytic agents can be injected via the inner lumen with an inflated balloon. The inflated balloon helped to keep the venous flow from washing out the thrombolytic agent, thus facilitating the agent's effect. Results. The first 10 patients received only anticoagulation therapy with heparin and warfarin for periods

  8. Improving Congestive Heart Failure Care with a Clinical Decision Unit.

    PubMed

    Carpenter, Jo Ellen; Short, Nancy; Williams, Tracy E; Yandell, Ben; Bowers, Margaret T

    2015-01-01

    Evidence supporting the development of Clinical Decision Units (CDUs) to impact congestive heart failure readmission rates comes from several categories of the literature. In this study, a pre-post design with comparison group was used to evaluate the impact of the CDU. Early changes in clinical and financial outcome indicators are encouraging. Nurse leaders seek ways to improve clinical outcomes while managing the current financially challenging environment. Implementation of a CDU provides many opportunities for nurse leaders to positively impact clinical care and financial performance within their institutions.

  9. Germany's Disease Management Program: Improving Outcomes in Congestive Heart Failure

    PubMed Central

    Kottmair, Stefan; Frye, Christian; Ziegenhagen, Dieter J.

    2005-01-01

    Hospital admissions among patients with congestive heart failure (CHF) are a major contributor to health care costs. A comprehensive disease management program for CHF was developed for private and statutory health insurance companies in order to improve health outcomes and reduce rehospitalization rates and costs. The program comprises care calls, written training material, telemetric monitoring, and health reports. Currently, 909 members from six insurance companies are enrolled. Routine evaluation, based on medical data warehouse software, demonstrates benefits in terms of improved health outcomes and processes of care. Economical evaluation of claims data indicates significant cost savings in a pre/post study design. PMID:17288080

  10. Anesthesia and congestive heart failure: pathology, medical, and surgical management.

    PubMed

    Armstrong, Christopher S; Hoover, Jason M; Fox, Charles J; Field, Aaron M; Richards, Todd A; Islam, Sameer R; Kaye, Alan D

    2006-06-01

    Congestive heart failure (CHF) is increasingly being recognized as a health problem in the United States. It is estimated that the lifetime risk for CHF is 1 in 5. The clinical anesthesiologist can expect to see several cases involving patients suffering from CHF. Because of the danger associated with surgery in a patient with CHF, a thorough knowledge of the disorder and the potential effects on the delivery of anesthetics must be considered. In addition, knowledge of the disease process and its manifestations is required for smooth guidance of the patient through the perioperative period. The understanding of current pharmacotherapies, surgical procedures and their implications related to interactions with anesthetics are all discussed.

  11. Germany's disease management program: improving outcomes in congestive heart failure.

    PubMed

    Kottmair, Stefan; Frye, Christian; Ziegenhagen, Dieter J

    2005-01-01

    Hospital admissions among patients with congestive heart failure (CHF) are a major contributor to health care costs. A comprehensive disease management program for CHF was developed for private and statutory health insurance companies in order to improve health outcomes and reduce rehospitalization rates and costs. The program comprises care calls, written training material, telemetric monitoring, and health reports. Currently, 909 members from six insurance companies are enrolled. Routine evaluation, based on medical data warehouse software, demonstrates benefits in terms of improved health outcomes and processes of care. Economical evaluation of claims data indicates significant cost savings in a pre/post study design.

  12. Pharmacodynamics and pharmacokinetics of oral levosimendan and its metabolites in patients with severe congestive heart failure: a dosing interval study.

    PubMed

    Põder, Pentti; Eha, Jaan; Sundberg, Stig; Antila, Saila; Heinpalu, Marika; Loogna, Imbrit; Planken, Ulle; Rantanen, Satu; Lehtonen, Lasse

    2004-10-01

    The objective of this study was to explore the pharmacodynamics and pharmacokinetics of oral levosimendan in patients with severe congestive heart failure. This was a randomized, parallel-group, double-blind, placebo-controlled trial. Oral levosimendan 2 to 8 mg daily or placebo was administered to 25 patients with New York Heart Association class III-IV congestive heart failure for 4 weeks. Pharmacodynamic variables consisted of heart rate-corrected electromechanical systole, heart rate, and systolic and diastolic blood pressure. The pharmacokinetics of levosimendan and its metabolites, OR-1855 and OR-1896, was assessed. The 4- to 8-mg daily doses of oral levosimendan showed moderate inotropic effects. Blood pressure remained unchanged with all doses. A moderate increase in heart rate was observed except with the 2-mg dose. Pharmacokinetic parameters of the metabolites increased linearly with the dose (P < or = .002 for Cmax and AUC0-8h for both treatment groups). It was concluded that oral levosimendan has inotropic and chronotropic effects in patients with severe congestive heart failure. Plasma concentrations of its metabolites increase dose dependently.

  13. The impact of congestion charging on social capital.

    PubMed

    Munford, Luke A

    2017-03-01

    We analyse a new data set to examine how congestion charging policies affect an individual's investment social capital. We exploit a (quasi-) natural experiment - the implementation of the Western Extension Zone (WEZ) to the London Congestion Charging zone in 2007. We measure investment in social capital by using the frequency of visits to friends and family before and after the implementation of the WEZ. Using longitudinal data collected in January and November 2007 made available by Transport for London, we perform difference-in-difference analysis, using both OLS and interval regression, with the treatment group defined as those who used a car to make visits pre-WEZ. We observe large and statistically significant reductions in visits as a result of the WEZ, with, for example, a reduction of around 20 visits a year to friends. The effect of the WEZ on the number of visits to act as an informal carer is much larger, with reductions of around 100 visits a year. Given that the changes occurred in such a small time frame (10 months), we conclude that the WEZ is likely to be the main driver of these reductions.

  14. Congestion phenomena caused by matching pennies in evolutionary games

    NASA Astrophysics Data System (ADS)

    Szabó, György; Szolnoki, Attila

    2015-03-01

    Evolutionary social dilemma games are extended by an additional matching-pennies game that modifies the collected payoffs. In a spatial version players are distributed on a square lattice and interact with their neighbors. First, we show that the matching-pennies game can be considered as the microscopic force of the Red Queen effect that breaks the detailed balance and induces eddies in the microscopic probability currents if the strategy update is analogous to the Glauber dynamics for the kinetic Ising models. The resulting loops in probability current breaks symmetry between the chessboardlike arrangements of strategies via a bottleneck effect occurring along the four-edge loops in the microscopic states. The impact of this congestion is analogous to the application of a staggered magnetic field in the Ising model; that is, the order-disorder critical transition is wiped out by noise. It is illustrated that the congestion induced symmetry breaking can be beneficial for the whole community within a certain region of parameters.

  15. [Juvenile haemochromatosis presenting as intractable congestive heart failure].

    PubMed

    Vas, Katalin; Hubay, Marta; Tordai, Attila; Andrikovics, Hajnalka; Zoltán, Sápi; Jánosi, András

    2005-12-18

    Juvenile haemochromatosis is an autosomal, recessive inherited iron metabolism disorder. The rapid deterioration and malignant prognosis differentiate juvenile haemochromatosis from hereditary haemochromatosis. The authors summarize the history of a 25 year old man, who worked in Hungary as a guest worker living in Romania. No significant illness has occurred in his previous history. The abdominal pain was his first symptom and he was treated in different institutions, where cholecystitis, alcoholic hepatic disease, hepatic cirrhosis were considered as a cause of his symptoms. Some weeks later atrial tachycardia, and congestive heart failure were observed and he was sent to our Cardiology Department. The echocardiography revealed diffuse hypokinesis, serious systolic dysfunction (ejection fraction: 21%), grade II mitral and tricuspid insufficiency with pulmonary hypertension. Considering the rapid deterioration of his cardiac function, myocarditis was suspected. Myocardial biopsy and coronary arteriography were performed. Coronary arteries were normal. Ventricular fibrillation occurred during coronary arteriography. Myocardial biopsy revealed juvenile haemochromatosis. Special laboratory examinations (transferrin saturation) were made after biopsy, that also confirmed the diagnosis of juvenile haemochromatosis. Cardiac transplantation was planned. Some days after the diagnosis was made the patient died of cardiogenic shock and intractable heart failure. Autopsy revealed hypogonadism and serious haemochromatosis in different parenchymal organs. Juvenile haemochromatosis should be considered in every young patient with congestive heart failure of unknown etiology.

  16. Improving UDP/IP Transmission Without Increasing Congestion

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott

    2006-01-01

    Datagram Retransmission (DGR) is a computer program that, within certain limits, ensures the reception of each datagram transmitted under the User Datagram Protocol/Internet Protocol. [User Datagram Protocol (UDP) is considered unreliable because it does not involve a reliability-ensuring connection-initiation dialogue between sender and receiver. UDP is well suited to issuing of many small messages to many different receivers.] Unlike prior software for ensuring reception of UDP datagrams, DGR does not contribute to network congestion by retransmitting data more frequently as an ever-increasing number of messages and acknowledgements is lost. Instead, DGR does just the opposite: DGR includes an adaptive timeout-interval- computing component that provides maximum opportunity for reception of acknowledgements, minimizing retransmission. By monitoring changes in the rate at which message-transmission transactions are completed, DGR detects changes in the level of congestion and responds by imposing varying degrees of delay on the transmission of new messages. In addition, DGR maximizes throughput by not waiting for acknowledgement of a message before sending the next message. All DGR communication is asynchronous, to maximize efficient utilization of network connections. DGR manages multiple concurrent datagram transmission and acknowledgement conversations.

  17. A Bayesian ridge regression analysis of congestion's impact on urban expressway safety.

    PubMed

    Shi, Qi; Abdel-Aty, Mohamed; Lee, Jaeyoung

    2016-03-01

    With the rapid growth of traffic in urban areas, concerns about congestion and traffic safety have been heightened. This study leveraged both Automatic Vehicle Identification (AVI) system and Microwave Vehicle Detection System (MVDS) installed on an expressway in Central Florida to explore how congestion impacts the crash occurrence in urban areas. Multiple congestion measures from the two systems were developed. To ensure more precise estimates of the congestion's effects, the traffic data were aggregated into peak and non-peak hours. Multicollinearity among traffic parameters was examined. The results showed the presence of multicollinearity especially during peak hours. As a response, ridge regression was introduced to cope with this issue. Poisson models with uncorrelated random effects, correlated random effects, and both correlated random effects and random parameters were constructed within the Bayesian framework. It was proven that correlated random effects could significantly enhance model performance. The random parameters model has similar goodness-of-fit compared with the model with only correlated random effects. However, by accounting for the unobserved heterogeneity, more variables were found to be significantly related to crash frequency. The models indicated that congestion increased crash frequency during peak hours while during non-peak hours it was not a major crash contributing factor. Using the random parameter model, the three congestion measures were compared. It was found that all congestion indicators had similar effects while Congestion Index (CI) derived from MVDS data was a better congestion indicator for safety analysis. Also, analyses showed that the segments with higher congestion intensity could not only increase property damage only (PDO) crashes, but also more severe crashes. In addition, the issues regarding the necessity to incorporate specific congestion indicator for congestion's effects on safety and to take care of the

  18. Abnormalities of capillary microarchitecture in a rat model of coronary ischemic congestive heart failure.

    PubMed

    Chen, Jiqiu; Yaniz-Galende, Elisa; Kagan, Heather J; Liang, Lifan; Hekmaty, Saboor; Giannarelli, Chiara; Hajjar, Roger

    2015-04-15

    The aim of the present study is to explore the role of capillary disorder in coronary ischemic congestive heart failure (CHF). CHF was induced in rats by aortic banding plus ischemia-reperfusion followed by aortic debanding. Coronary arteries were perfused with plastic polymer containing fluorescent dye. Multiple fluorescent images of casted heart sections and scanning electric microscope of coronary vessels were obtained to characterize changes in the heart. Cardiac function was assessed by echocardiography and in vivo hemodynamics. Stenosis was found in all levels of the coronary arteries in CHF. Coronary vasculature volume and capillary density in remote myocardium were significantly increased in CHF compared with control. This occurred largely in microvessels with a diameter of ≤3 μm. Capillaries in CHF had a tortuous structure, while normal capillaries were linear. Capillaries in CHF had inconsistent diameters, with assortments of narrowed and bulged segments. Their surfaces appeared rough, potentially indicating endothelial dysfunction in CHF. Segments of main capillaries between bifurcations were significantly shorter in length in CHF than in control. Transiently increasing preload by injecting 50 μl of 30% NaCl demonstrated that the CHF heart had lower functional reserve; this may be associated with congestion in coronary microcirculation. Ischemic coronary vascular disorder is not limited to the main coronary arteries, as it occurs in arterioles and capillaries. Capillary disorder in CHF included stenosis, deformed structure, proliferation, and roughened surfaces. This disorder in the coronary artery architecture may contribute to the reduction in myocyte contractility in the setting of heart failure.

  19. Abnormalities of capillary microarchitecture in a rat model of coronary ischemic congestive heart failure

    PubMed Central

    Chen, Jiqiu; Yaniz-Galende, Elisa; Kagan, Heather J.; Liang, Lifan; Hekmaty, Saboor; Giannarelli, Chiara

    2015-01-01

    The aim of the present study is to explore the role of capillary disorder in coronary ischemic congestive heart failure (CHF). CHF was induced in rats by aortic banding plus ischemia-reperfusion followed by aortic debanding. Coronary arteries were perfused with plastic polymer containing fluorescent dye. Multiple fluorescent images of casted heart sections and scanning electric microscope of coronary vessels were obtained to characterize changes in the heart. Cardiac function was assessed by echocardiography and in vivo hemodynamics. Stenosis was found in all levels of the coronary arteries in CHF. Coronary vasculature volume and capillary density in remote myocardium were significantly increased in CHF compared with control. This occurred largely in microvessels with a diameter of ≤3 μm. Capillaries in CHF had a tortuous structure, while normal capillaries were linear. Capillaries in CHF had inconsistent diameters, with assortments of narrowed and bulged segments. Their surfaces appeared rough, potentially indicating endothelial dysfunction in CHF. Segments of main capillaries between bifurcations were significantly shorter in length in CHF than in control. Transiently increasing preload by injecting 50 μl of 30% NaCl demonstrated that the CHF heart had lower functional reserve; this may be associated with congestion in coronary microcirculation. Ischemic coronary vascular disorder is not limited to the main coronary arteries, as it occurs in arterioles and capillaries. Capillary disorder in CHF included stenosis, deformed structure, proliferation, and roughened surfaces. This disorder in the coronary artery architecture may contribute to the reduction in myocyte contractility in the setting of heart failure. PMID:25659485

  20. Traffic Congestion on a University Campus: A Consideration of Unconventional Remedies to Nontraditional Transportation Patterns

    ERIC Educational Resources Information Center

    Kaplan, Dave; Clapper, Thomas

    2007-01-01

    U.S. transportation data suggest that the number of vehicle miles traveled has far surpassed new capacity, resulting in increased traffic congestion in many communities throughout the country. This article reports on traffic congestion around a university campus located within a small town. The mix of trip purposes varies considerably in this…

  1. 23 CFR 973.214 - Indian lands congestion management system (CMS).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Indian lands congestion management system (CMS). 973.214... (CMS). (a) For purposes of this section, congestion means the level at which transportation system... the tribes, shall develop criteria to determine when a CMS is to be implemented for a...

  2. 23 CFR 973.214 - Indian lands congestion management system (CMS).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Indian lands congestion management system (CMS). 973.214... (CMS). (a) For purposes of this section, congestion means the level at which transportation system... the tribes, shall develop criteria to determine when a CMS is to be implemented for a...

  3. 23 CFR 973.214 - Indian lands congestion management system (CMS).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Indian lands congestion management system (CMS). 973.214... (CMS). (a) For purposes of this section, congestion means the level at which transportation system... the tribes, shall develop criteria to determine when a CMS is to be implemented for a...

  4. 23 CFR 973.214 - Indian lands congestion management system (CMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Indian lands congestion management system (CMS). 973.214... (CMS). (a) For purposes of this section, congestion means the level at which transportation system... the tribes, shall develop criteria to determine when a CMS is to be implemented for a...

  5. 23 CFR 973.214 - Indian lands congestion management system (CMS).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Indian lands congestion management system (CMS). 973.214... HIGHWAYS MANAGEMENT SYSTEMS PERTAINING TO THE BUREAU OF INDIAN AFFAIRS AND THE INDIAN RESERVATION ROADS PROGRAM Bureau of Indian Affairs Management Systems § 973.214 Indian lands congestion management...

  6. 23 CFR 972.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Federal lands congestion management system (CMS). 972... LANDS HIGHWAYS FISH AND WILDLIFE SERVICE MANAGEMENT SYSTEMS Fish and Wildlife Service Management Systems § 972.214 Federal lands congestion management system (CMS). (a) For purposes of this section,...

  7. 23 CFR 970.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Federal lands congestion management system (CMS). 970... LANDS HIGHWAYS NATIONAL PARK SERVICE MANAGEMENT SYSTEMS National Park Service Management Systems § 970.214 Federal lands congestion management system (CMS). (a) For purposes of this section,...

  8. Congestion at Card and Book Catalogs--A Queuing-Theory Approach

    ERIC Educational Resources Information Center

    Bookstein, Abraham

    1972-01-01

    This paper attempts to analyze the problem of congestion, using a mathematical model shown to be of value in other similar applications. Three criteria of congestion are considered, and it is found that the conclusion one can draw is sensitive to which of these criteria is paramount. (8 references) (Author/NH)

  9. Liver congestion in heart failure contributes to inappropriately increased serum hepcidin despite anemia.

    PubMed

    Ohno, Yukako; Hanawa, Haruo; Jiao, Shuang; Hayashi, Yuka; Yoshida, Kaori; Suzuki, Tomoyasu; Kashimura, Takeshi; Obata, Hiroaki; Tanaka, Komei; Watanabe, Tohru; Minamino, Tohru

    2015-01-01

    Hepcidin is a key regulator of mammalian iron metabolism and mainly produced by the liver. Hepcidin excess causes iron deficiency and anemia by inhibiting iron absorption from the intestine and iron release from macrophage stores. Anemia is frequently complicated with heart failure. In heart failure patients, the most frequent histologic appearance of liver is congestion. However, it remains unclear whether liver congestion associated with heart failure influences hepcidin production, thereby contributing to anemia and functional iron deficiency. In this study, we investigated this relationship in clinical and basic studies. In clinical studies of consecutive heart failure patients (n = 320), anemia was a common comorbidity (41%). In heart failure patients without active infection and ongoing cancer (n = 30), log-serum hepcidin concentration of patients with liver congestion was higher than those without liver congestion (p = 0.0316). Moreover, in heart failure patients with liver congestion (n = 19), the anemia was associated with the higher serum hepcidin concentrations, which is a type of anemia characterized by induction of hepcidin. Subsequently, we produced a rat model of heart failure with liver congestion by injecting monocrotaline that causes pulmonary hypertension. The monocrotaline-treated rats displayed liver congestion with increase of hepcidin expression at 4 weeks after monocrotaline injection, followed by anemia and functional iron deficiency observed at 5 weeks. We conclude that liver congestion induces hepcidin production, which may result in anemia and functional iron deficiency in some patients with heart failure.

  10. Clustering and congestion effects on cascading failures of scale-free networks

    NASA Astrophysics Data System (ADS)

    Zheng, J.-F.; Gao, Z.-Y.; Zhao, X.-M.

    2007-09-01

    In this work, we study cascading failures of scale-free networks by considering congestion effects, which should be very common in the transportation or communication systems. In terms of User Equilibrium condition, congestion effects can be described by cost functions or link performance functions, which map link flows to travel times. The cost on the link represents the travel time when passing through the link. Betweenness centrality of the link is introduced to define the "practical capacity" of the link in the cost function. Different from betweeness centrality, by considering congestion effects, load dynamics can be determined in a more meaningful way. Simulation results indicate that, due to congestion effects, load distribution may become sensitive to the initial node removals for the scale-free networks. Moreover, based on congestion effects, scale-free networks with larger clustering coefficients are more sensitive to cascading failures.

  11. Estimation of congestion in free disposal hull models using data envelopment analysis.

    PubMed

    Abbasi, M; Jahanshahloo, G R; Rostamy-Malkhlifeh, M; Hosseinzadeh Lotfi, F

    2014-01-01

    This paper deals with evaluating congestion in free disposal hull (FDH) models. There are several approaches in data envelopment analysis (DEA) literatures which discuss the theory and application of congestion. However, almost all of these approaches considered convex DEA technologies. So, in the case of nonconvex technologies, including FDH technology, this field is almost nil. This paper makes an attempt to fill in this void. To do so, this study provides a pairwise comparisons-based algorithm to evaluate congestion in FDH model. This algorithm identifies the sources of congestion and estimates its amounts. It is also capable of detecting the losses amounts of output due to congestion. The validity of the proposed model is demonstrated using some numerical and empirical examples.

  12. Complexity in congestive heart failure: A time-frequency approach

    NASA Astrophysics Data System (ADS)

    Banerjee, Santo; Palit, Sanjay K.; Mukherjee, Sayan; Ariffin, MRK; Rondoni, Lamberto

    2016-03-01

    Reconstruction of phase space is an effective method to quantify the dynamics of a signal or a time series. Various phase space reconstruction techniques have been investigated. However, there are some issues on the optimal reconstructions and the best possible choice of the reconstruction parameters. This research introduces the idea of gradient cross recurrence (GCR) and mean gradient cross recurrence density which shows that reconstructions in time frequency domain preserve more information about the dynamics than the optimal reconstructions in time domain. This analysis is further extended to ECG signals of normal and congestive heart failure patients. By using another newly introduced measure—gradient cross recurrence period density entropy, two classes of aforesaid ECG signals can be classified with a proper threshold. This analysis can be applied to quantifying and distinguishing biomedical and other nonlinear signals.

  13. Psychobiology of depression/distress in congestive heart failure

    PubMed Central

    Hassan, Mustafa; Sheps, David S.

    2011-01-01

    Heart failure affects millions of Americans and new diagnosis rates are expected to almost triple over the next 30 years as our population ages. Affective disorders including clinical depression and anxiety are common in patients with congestive heart failure. Furthermore, the presence of these disorders significantly impacts quality of life, medical outcomes, and healthcare service utilization. In recent years, the literature has attempted to describe potential pathophysiologic mechanisms relating affective disorders and psychosocial stress to heart failure. Several potential mechanisms have been proposed including autonomic nervous system dysfunction, inflammation, cardiac arrhythmias, and altered platelet function. These mechanisms are reviewed in this article. Additional novel mechanisms such as mental stress-induced myocardial ischemia are also discussed. PMID:18368481

  14. Hospital discharge plan for patients with congestive heart failure.

    PubMed

    Andrietta, Maria Paula; Lopes Moreira, Rita Simone; Bottura Leite de Barros, Alba Lucia

    2011-01-01

    This integrative review investigates how nurses plan the hospital discharge of patients with Congestive Heart Failure (CHF) since an inadequate discharge plan and patients' subsequent non-adherence to instruction provided upon discharge are indicated as potential factors for re-hospitalization. A total of 24 papers were found in a search carried out in the LILACS and MEDLINE databases between 2004 and 2008, which given the inclusion criteria, were reduced to 14 papers. The papers were analyzed and categorized into "Health Education", and "Nursing Care". The synthesis of results indicates that the discharge plan devised by nurses is based on two categories. The actions of nurses to promote health education can enable patients with CHF to improve self-care.

  15. Problems of rapid digitalization in severe congestive heart failure.

    PubMed

    Haustein, K O; Assmann, I; Fiehring, H

    1980-02-01

    The pharmacodynamic effects (changes of systolic time intervals, STI, reaction of pulmonary arterial pressure) of digitoxin were studied in 7 patients with severe congestive heart failure in comparison with the corresponding plasma level. STI indicated glycoside-dependent changes, i.e. shortening of LVETc and QS2c and normalization of prolonged PEPc, while ICT shortening was less observed. In 2 patients with cor pulmonale a pulmonary oedema occurred accompanied with prolonged LVETc. During the early period of glycoside-dependent recompensation no significant correlation between STI shortening and glycoside plasma level was observed. Because of the retarded normalization of the haemodynamics of the pulmonary circulation and because of possible side-effects, rapid digitalization has to be reconsidered.

  16. Relation of systemic and local muscle exercise capacity to skeletal muscle characteristics in men with congestive heart failure

    NASA Technical Reports Server (NTRS)

    Massie, B. M.; Simonini, A.; Sahgal, P.; Wells, L.; Dudley, G. A.

    1996-01-01

    OBJECTIVES. The present study was undertaken to further characterize changes in skeletal muscle morphology and histochemistry in congestive heart failure and to determine the relation of these changes to abnormalities of systemic and local muscle exercise capacity. BACKGROUND. Abnormalities of skeletal muscle appear to play a role in the limitation of exercise capacity in congestive heart failure, but information on the changes in muscle morphology and biochemistry and their relation to alterations in muscle function is limited. METHODS. Eighteen men with predominantly mild to moderate congestive heart failure (mean +/- SEM New York Heart Association functional class 2.6 +/- 0.2, ejection fraction 24 +/- 2%) and eight age- and gender-matched sedentary control subjects underwent measurements of peak systemic oxygen consumption (VO2) during cycle ergometry, resistance to fatigue of the quadriceps femoris muscle group and biopsy of the vastus lateralis muscle. RESULTS. Peak VO2 and resistance to fatigue were lower in the patients with heart failure than in control subjects (15.7 +/- 1.2 vs. 25.1 +/- 1.5 ml/min-kg and 63 +/- 2% vs. 85 +/- 3%, respectively, both p < 0.001). Patients had a lower proportion of slow twitch, type I fibers than did control subjects (36 +/- 3% vs. 46 +/- 5%, p = 0.048) and a higher proportion of fast twitch, type IIab fibers (18 +/- 3% vs. 7 +/- 2%, p = 0.004). Fiber cross-sectional area was smaller, and single-fiber succinate dehydrogenase activity, a mitochondrial oxidative marker, was lower in patients (both p < or = 0.034). Likewise, the ratio of average fast twitch to slow twitch fiber cross-sectional area was lower in patients (0.780 +/- 0.06 vs. 1.05 +/- 0.08, p = 0.019). Peak VO2 was strongly related to integrated succinate dehydrogenase activity in patients (r = 0.896, p = 0.001). Peak VO2, resistance to fatigue and strength also correlated significantly with several measures of fiber size, especially of fast twitch fibers, in

  17. Congestive hepatic fibrosis score: a novel histologic assessment of clinical severity.

    PubMed

    Dai, Dao-Fu; Swanson, Paul E; Krieger, Eric V; Liou, Iris W; Carithers, Robert L; Yeh, Matthew M

    2014-12-01

    Chronic right heart failure predisposes to hepatic passive congestion and centrizonal necrosis that may lead to hepatic fibrosis (cardiac sclerosis). Although there have been several studies on the histologic features of congestive hepatopathy, there is no available grading system. In this study we developed a novel grading system for congestive hepatic fibrosis. Liver biopsies were examined in patients with chronic heart failure of various etiologies including congenital heart disease, idiopathic cardiomyopathy, ischemic heart disease, and valvular heart disease. The cases with available echocardiography and/or right heart catheterization were included. Cases with other types of underlying chronic liver diseases, alcoholic liver disease, significant steatosis (>20%), malignant neoplasm, and acute heart failure or shock were excluded. After exclusion, 42 cases were included in the study. We herein proposed a novel congestive hepatic fibrosis score and correlated it with the right heart structure and function obtained by echocardiography and/or right heart catheterization. Our results showed that congestive hepatic fibrosis score is well correlated with the right atrial pressure (P for trend <0.001). The presence of portal fibrosis (congestive hepatic fibrosis scores 2 and 3) is associated with significantly higher right atrial pressure than those with no fibrosis (P<0.001) or with centrizonal fibrosis only (P=0.02). Congestive hepatic fibrosis score is also significantly associated with increasing severity of right atrial dilatation (P=0.03) and right ventricular dilatation (P=0.02), indicators for chronic volume and/or pressure overload. Other histopathologic features include sinusoidal dilatation and centrizonal hepatocyte atrophy. In summary, although sinusoidal dilatation and centrizonal fibrosis are the hallmarks of hepatic passive congestion, the presence of portal fibrosis is suggestive of more advanced disease, as it correlates with more severe impairment

  18. Quantum random walks on congested lattices and the effect of dephasing

    PubMed Central

    Motes, Keith R.; Gilchrist, Alexei; Rohde, Peter P.

    2016-01-01

    We consider quantum random walks on congested lattices and contrast them to classical random walks. Congestion is modelled on lattices that contain static defects which reverse the walker’s direction. We implement a dephasing process after each step which allows us to smoothly interpolate between classical and quantum random walks as well as study the effect of dephasing on the quantum walk. Our key results show that a quantum walker escapes a finite boundary dramatically faster than a classical walker and that this advantage remains in the presence of heavily congested lattices. PMID:26812924

  19. Diagnosis and Treatment of Depression in Patients With Congestive Heart Failure: A Review of the Literature

    PubMed Central

    Stern, Theodore A.; Hebert, Kathy A.; Musselman, Dominique L.

    2013-01-01

    Context: Major depressive disorder (MDD) can be challenging to diagnose in patients with congestive heart failure, who often suffer from fatigue, insomnia, weight changes, and other neurovegetative symptoms that overlap with those of depression. Pathophysiologic mechanisms (eg, inflammation, autonomic nervous system dysfunction, cardiac arrhythmias, and altered platelet function) connect depression and congestive heart failure. Objective: We sought to review the prevalence, diagnosis, neurobiology, and treatment of depression associated with congestive heart failure. Data Sources: A search of all English-language articles between January 2003 and January 2013 was conducted using the search terms congestive heart failure and depression. Study Selection: We found 1,498 article abstracts and 19 articles (meta-analyses, systematic reviews, and original research articles) that were selected for inclusion, as they contained information about our focus on diagnosis, treatment, and pathophysiology of depression associated with congestive heart failure. The search was augmented with manual review of reference lists of articles from the initial search. Articles selected for review were determined by author consensus. Data Extraction: The prevalence, diagnosis, neurobiology, and treatment of depression associated with congestive heart failure were reviewed. Particular attention was paid to the safety, efficacy, and tolerability of antidepressant medications commonly used to treat depression and how their side-effect profiles impact the pathophysiology of congestive heart failure. Drug-drug interactions between antidepressant medications and medications used to treat congestive heart failure were examined. Results: MDD is highly prevalent in patients with congestive heart failure. Moreover, the prevalence and severity of depression correlate with the degree of cardiac dysfunction and development of congestive heart failure. Depression increases the risk of congestive heart

  20. The effects of congestions tax on air quality and health

    NASA Astrophysics Data System (ADS)

    Johansson, Christer; Burman, Lars; Forsberg, Bertil

    The "Stockholm Trial" involved a road pricing system to improve the air quality and reduce traffic congestion. The test period of the trial was January 3-July 31, 2006. Vehicles travelling into and out of the charge cordon were charged for every passage during weekdays. The amount due varied during the day and was highest during rush hours (20 SEK = 2.2 EUR, maximum 60 SEK per day). Based on measured and modelled changes in road traffic it was estimated that this system resulted in a 15% reduction in total road use within the charged cordon. Total traffic emissions in this area of NO x and PM10 fell by 8.5% and 13%, respectively. Air quality dispersion modelling was applied to assess the effect of the emission reductions on ambient concentrations and population exposure. For the situations with and without the trial, meteorological conditions and other emissions than from road traffic were kept the same. The calculations show that, with a permanent congestion tax system like the Stockholm Trial, the annual average NO x concentrations would be lower by up to 12% along the most densely trafficked streets. PM10 concentrations would be up to 7% lower. The limit values for both PM10 and NO 2 would still be exceeded along the most densely trafficked streets. The total population exposure of NO x in Greater Stockholm (35 × 35 km with 1.44 million people) is estimated to decrease with a rather modest 0.23 μg m -3. However, based on a long-term epidemiological study, that found an increased mortality risk of 8% per 10 μg m -3 NO x, it is estimated that 27 premature deaths would be avoided every year. According to life-table analysis this would correspond to 206 years of life gained over 10 years per 100 000 people following the trial if the effects on exposures would persist. The effect on mortality is attributed to road traffic emissions (likely vehicle exhaust particles); NO x is merely regarded as an indicator of traffic exposure. This is only the tip of the ice

  1. Flexible and scalable wavelength multicast of coherent optical OFDM with tolerance against pump phase-noise using reconfigurable coherent multi-carrier pumping.

    PubMed

    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.

  2. Exogenous midkine administration prevents cardiac remodeling in pacing-induced congestive heart failure of rabbits.

    PubMed

    Harada, Masahide; Hojo, Mayumi; Kamiya, Kaichiro; Kadomatsu, Kenji; Murohara, Toyoaki; Kodama, Itsuo; Horiba, Mitsuru

    2016-01-01

    Midkine (MK), a heparin-binding growth factor, has been shown to prevent cardiac remodeling after ischemic injury through its anti-apoptotic effect. Cell apoptosis is central to the pathophysiology of cardiac remodeling in congestive heart failure (CHF) of ischemic as well as non-ischemic origin. We hypothesized that MK exerts the anti-apoptotic cardioprotective effect in CHF of non-ischemic etiology. MK protein or vehicle (normal saline) was subcutaneously administered in tachycardia-induced CHF rabbits (right ventricular pacing, 350 beats/min, 4 weeks). The vehicle-treated rabbits (n = 19, control) demonstrated severe CHF and high mortality rate, whereas MK (n = 16) demonstrated a well-compensated state and a lower mortality rate. In echocardiography, left ventricular (LV) end-diastolic dimension decreased in MK versus control, whereas LV systolic function increased. In histological analysis (picrosirius red staining), MK decreased collagen deposition area compared with control. TUNEL staining showed that MK prevented cell apoptosis and minimized myocyte loss in the CHF rabbit ventricle, associated with activation of PI3-K/Akt signaling, producing a parallel decrease of Bax/Bcl-2 ratio. MK prevented progression of cardiac remodeling in the CHF rabbit, likely by activation of anti-apoptotic signaling. Exogenous MK application might be a novel therapeutic strategy for CHF due to non-ischemic origin.

  3. Optimal information transmission in organizations: search and congestion

    SciTech Connect

    Arenas, A.; Cabrales, A.; Danon, L.; Diaz-Guilera, A.; Guimera, R.; Vega-Redondo, F.

    2008-01-01

    We propose a stylized model of a problem-solving organization whose internal communication structure is given by a fixed network. Problems arrive randomly anywhere in this network and must find their way to their respective specialized solvers by relying on local information alone. The organization handles multiple problems simultaneously. For this reason, the process may be subject to congestion. We provide a characterization of the threshold of collapse of the network and of the stock of floating problems (or average delay) that prevails below that threshold. We build upon this characterization to address a design problem: the determination of what kind of network architecture optimizes performance for any given problem arrival rate. We conclude that, for low arrival rates, the optimal network is very polarized (i.e. star-like or centralized), whereas it is largely homogeneous (or decentralized) for high arrival rates. These observations are in line with a common transformation experienced by information-intensive organizations as their work flow has risen in recent years.

  4. Pelvic congestion syndrome masquerading as osteoarthritis of the hip

    PubMed Central

    Dos Santos, Scott J; Whiteley, Mark S

    2016-01-01

    Objectives: Pelvic congestion syndrome (PCS) is associated with pelvic vein reflux (PVR), occasionally secondary to venous compression. Its symptoms, usually intra-pelvic, are alleviated following the abolition of this reflux by pelvic vein embolisation (PVE). The objective of this report is to present two cases of left hip pain, erroneously diagnosed as osteoarthritis, which disappeared after successful PVE and abolition of PVR. Methods: Two females presented with lower limb varicose veins, and also had a history of left-sided hip pain. Both had previously been investigated for the hip pain and diagnosed as osteoarthritis despite minimal arthritic changes on pelvic X-rays. During investigation for lower limb varicose veins, both showed a pelvic origin for their leg veins and hence underwent transvaginal duplex ultrasound. This revealed PVR, and PVE was planned in both patients. Results: Both patients underwent PVE and reported ‘miraculous’ resolution of left hip pain and also PCS symptoms including pelvic pain, irritable bowel issues and the disappearance of pelvic dragging, with almost immediate disappearance of vulval and vaginal varicosities. One patient also noted reduced clitoral sensitivity. Conclusion: Manifestations of PCS may vary in terms of intra- or extra-pelvic signs. PCS and PVR should be considered in the differential diagnosis of patients with arthritic symptoms in the hip without evident radiographic evidence. PMID:27994874

  5. Nursing management of congestive heart failure. Part I.

    PubMed

    Dahlen, R; Roberts, S L

    1995-10-01

    Congestive heart failure (CHF) is a common clinical problem and in its advanced stage has a poor prognosis. Approximately 400,000 individuals develop heart failure each year (Parmley 1989). CHF can be caused by coronary artery disease such as myocardial infarction, ischemia and hypertension. Should heart failure occur as a result of acute myocardial infarction, a classification tool developed by Killip can be used to assess the degree of CHF. Killip's classification is organised into the following four categories: Class I: no heart failure Class II: mild to moderate failure Class III: acute pulmonary oedema Class IV: cardiogenic shock (Killip, as cited by Benz 1989). This system helps in organising clinical signs and symptoms of heart failure. Due to the fact that CHF is now the most common hospital discharge diagnosis for those over the age of 65, critical care nurses need to be able to recognise complications and intervene rapidly (Parmley 1989) in collaboration with medical staff. The purpose of this paper is first to discuss cardinal signs and symptoms and clinical data associated with CHF. Second, critical care nurses' management of CHF is organised around common nursing diagnoses.

  6. A Remote Patient Monitoring System for Congestive Heart Failure

    PubMed Central

    Suh, Myung-kyung; Chen, Chien-An; Woodbridge, Jonathan; Tu, Michael Kai; Kim, Jung In; Nahapetian, Ani; Evangelista, Lorraine S.; Sarrafzadeh, Majid

    2011-01-01

    Congestive heart failure (CHF) is a leading cause of death in the United States affecting approximately 670,000 individuals. Due to the prevalence of CHF related issues, it is prudent to seek out methodologies that would facilitate the prevention, monitoring, and treatment of heart disease on a daily basis. This paper describes WANDA (Weight and Activity with Blood Pressure Monitoring System); a study that leverages sensor technologies and wireless communications to monitor the health related measurements of patients with CHF. The WANDA system is a three-tier architecture consisting of sensors, web servers, and back-end databases. The system was developed in conjunction with the UCLA School of Nursing and the UCLA Wireless Health Institute to enable early detection of key clinical symptoms indicative of CHF-related decompensation. This study shows that CHF patients monitored by WANDA are less likely to have readings fall outside a healthy range. In addition, WANDA provides a useful feedback system for regulating readings of CHF patients. PMID:21611788

  7. Prognosis and possible presymptomatic manifestations of congestive cardiomyopathy (COCM).

    PubMed Central

    Kuhn, H.; Breithardt, G.; Knieriem, H. J.; Köhler, E.; Lösse, B.; Seipel, L.; Loogen, F.

    1978-01-01

    In order to find evidence of prognosis and of presymptomatic manifestation of congestive cardiomyopathy (COCM) in fifty-eight patients, the extent of morphological changes of endomyocardial catheter biopsy (EMCB), clinical and haemodynamic data were correlated to the clinical course. In addition, clinical, haemodynamic, angiographic, morphological and His-bundle electrographic studies were performed in patients with left bundle branch block (LBBB), normal left ventricular end-diastolic volume, and normal coronary arteries (n = 43). Related to a 10-year mortality rate of 70% from the onset of symptoms, COCM is one of the most severe heart diseases. Endomyocardial catheter biopsy (EMCB) allowed clear prognostic separation in patients with COCM and seems to be of diagnostic value in patients with only slightly enlarged hearts and in patients with a short history of symptoms. The studies also revealed much evidence that at least some patients with LBBB, normal left ventricular end-diastolic volume (LVEDV) and normal coronary arteries exhibit an early stage of COCM. In these patients especially EMCB with severe changes of heart muscle cells and/or impaired left ventricular function may indicate subsequent COCM. So that there is now a new indication for performing EMCB. PMID:704515

  8. Decrease of cardiac chaos in congestive heart failure

    NASA Astrophysics Data System (ADS)

    Poon, Chi-Sang; Merrill, Christopher K.

    1997-10-01

    The electrical properties of the mammalian heart undergo many complex transitions in normal and diseased states. It has been proposed that the normal heartbeat may display complex nonlinear dynamics, including deterministic chaos,, and that such cardiac chaos may be a useful physiological marker for the diagnosis and management, of certain heart trouble. However, it is not clear whether the heartbeat series of healthy and diseased hearts are chaotic or stochastic, or whether cardiac chaos represents normal or abnormal behaviour. Here we have used a highly sensitive technique, which is robust to random noise, to detect chaos. We analysed the electrocardiograms from a group of healthy subjects and those with severe congestive heart failure (CHF), a clinical condition associated with a high risk of sudden death. The short-term variations of beat-to-beat interval exhibited strongly and consistently chaotic behaviour in all healthy subjects, but were frequently interrupted by periods of seemingly non-chaotic fluctuations in patients with CHF. Chaotic dynamics in the CHF data, even when discernible, exhibited a high degree of random variability over time, suggesting a weaker form of chaos. These findings suggest that cardiac chaos is prevalent in healthy heart, and a decrease in such chaos may be indicative of CHF.

  9. Management of anemia in patients with congestive heart failure.

    PubMed

    Tim Goodnough, Lawrence; Comin-Colet, Josep; Leal-Noval, Santiago; Ozawa, Sherri; Takere, Jacqueline; Henry, David; Javidroozi, Mazyar; Hohmuth, Benjamin; Bisbe, Elvira; Gross, Irwin; Shander, Aryeh

    2017-01-01

    Anemia is an independent risk factor for adverse patient outcomes. There are no guidelines for management of anemia in patients with congestive heart failure (CHF), despite its high incidence. Four objectives were defined by the International Anemia Management and Clinical Outcomes Expert Panel (AMCO), a multinational group of interdisciplinary experts identified by the Society for the Advancement of Blood Management (SABM) to: determine the prevalence of anemia in outpatients; to determine the prevalence of hospital-acquired anemia; to assess the impact of anemia management on clinical outcomes such as quality of life and functional status; and to provide recommendations for primary care physicians and specialists for the diagnosis, evaluation, and management of anemia in patients with CHF. Anemia and iron deficiency were confirmed to be highly prevalent in patients with CHF. Intravenous iron therapy improves anemia, cardiac function and exercise tolerance, leading to improvement in quality of life. Anemia management has been demonstrated to be cost-effective. Clinical care pathways to manage anemia in patients with CHF are recommended as best practices in order to improve patient outcomes. Am. J. Hematol. 92:88-93, 2017. © 2016 Wiley Periodicals, Inc.

  10. 78 FR 67442 - Congestion Mitigation and Air Quality Improvement Program Interim Guidance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-12

    ... Federal Highway Administration Congestion Mitigation and Air Quality Improvement Program Interim Guidance... Mitigation and Air Quality Improvement (CMAQ) Program (Interim Guidance). The Interim Guidance revises CMAQ....gov/environment/air_quality/cmaq/policy_and_guidance/2008_guidance/ guidance/. DATES: This...

  11. Chance Constrained Input Relaxation to Congestion in Stochastic DEA. An Application to Iranian Hospitals.

    PubMed

    Kheirollahi, Hooshang; Matin, Behzad Karami; Mahboubi, Mohammad; Alavijeh, Mehdi Mirzaei

    2015-01-01

    This article developed an approached model of congestion, based on relaxed combination of inputs, in stochastic data envelopment analysis (SDEA) with chance constrained programming approaches. Classic data envelopment analysis models with deterministic data have been used by many authors to identify congestion and estimate its levels; however, data envelopment analysis with stochastic data were rarely used to identify congestion. This article used chance constrained programming approaches to replace stochastic models with "deterministic equivalents". This substitution leads us to non-linear problems that should be solved. Finally, the proposed method based on relaxed combination of inputs was used to identify congestion input in six Iranian hospital with one input and two outputs in the period of 2009 to 2012.

  12. Effects of tolvaptan on congestive heart failure complicated with chylothorax in a neonate.

    PubMed

    Sato, Nikiko; Sugiura, Tokio; Nagasaki, Rika; Suzuki, Kazutaka; Ito, Koichi; Kato, Takenori; Inukai, Sachiko; Saitoh, Shinji

    2015-10-01

    Tolvaptan is an oral vasopressin type 2 receptor antagonist that can be used for heart failure patients with hyponatremia or symptomatic congestion. Although the effects of tolvaptan in adults have been well documented, only limited information is available in children. The case of a neonate with congestive heart failure complicated with chylothorax after palliative surgery for transposition of the great arteries treated with tolvaptan is reported. Slow up-titration to 0.1 mg/kg successfully increased urine output and improved refractory congestive heart failure without hypernatremia. Subsequently, bodyweight and chylothorax decreased gradually. Moreover, the use of tolvaptan reduced the dosage of furosemide. Tolvaptan could be an alternative drug for neonates with congestive heart failure. Further large studies are needed to confirm the efficacy and identify the appropriate dose of tolvaptan in neonates.

  13. Congestive cardiomyopathy and endobronchial granulomas as manifestations of Churg-Strauss syndrome.

    PubMed Central

    Alvarez-Sala, R.; Prados, C.; Armada, E.; Del Arco, A.; Villamor, J.

    1995-01-01

    Churg-Strauss syndrome is a systemic vasculitis. Its most frequent complications are heart diseases and asthma. Usually, cardiological manifestations are pericarditis, cardiac failure and myocardial infarction. Endobronchial granulomas identified by bronchoscopy are unusual. We present the case of a man with congestive cardiomyopathy and endobronchial granulomas macroscopically visible at bronchoscopy. After a review of medical literature, we found one case of congestive cardiomyopathy and no cases of endobronchial granulomas observed by bronchoscopy associated with Churg-Strauss syndrome. Images Figure PMID:7644400

  14. Home care nursing for persons with congestive heart failure: description and relationship to hospital readmission.

    PubMed

    Martens, K H

    2000-06-01

    Although home care nursing has been associated with a lower rate of repeated hospitalization of persons with congestive heart failure, little is known about this relation. This study examined variables that reflect information about demographic characteristics, clinical status, nursing services, and repeated hospitalization for persons admitted with a primary diagnosis of congestive heart failure to one home care agency during one fiscal year. Implications related to assessment, documentation, patient instruction, and further research are discussed.

  15. A Study of Congestion in the Kansas City Southern Railway System

    DTIC Science & Technology

    2007-11-02

    used to test power’s relation to congestion. Friedman’s Rank Test , a nonparametric statistical model, tests the significance of power against eight...other factors in their relation to train delays. The second model tests the correlation between train time delays and number of ൬-hour cars." This...Pacific are summarized. Two quantitative models are used to test power’s relation to congestion. Friedman’s Rank Test , a nonparametric statistical model

  16. Acute and long-term renal and metabolic effects of piretanide in congestive cardiac failure.

    PubMed Central

    McNabb, W R; Noormohamed, F H; Lant, A F

    1988-01-01

    1. The renal and metabolic effects of the sulphamoylbenzoic acid diuretic, piretanide, have been studied, under controlled dietary conditions, in 39 patients with congestive cardiac failure. 2. In acute studies, peak saluresis occurred within 4 h of oral piretanide administration; saluresis was complete within 6 h, after which a significant antidiuretic effect was observed. Addition of triamterene, 50 mg, blunted the 0-6 h kaliuretic effect of piretanide. Over 24 h, piretanide, alone, caused insignificant urinary losses of potassium when compared with control. 3. In comparative studies, the piretanide dose-response curve was found to be parallel to that of frusemide over the dose range studied. The 0-6 h saluretic responses of piretanide, 6, 12 and 18 mg, were found to be equivalent to frusemide, 40, 80 and 120 mg respectively. The collective mean ratios of all the saluretic responses to each dose of piretanide with the corresponding dose of frusemide was observed to be 0.99 +/- 0.12, over 0-6 h period, and 0.86 +/- 0.09 over the 24 h period. The relative potency of piretanide, when compared with frusemide was found to be 6.18 (95% confidence limits 4.87-8.33), over the 0-6 h period, and 4.73 (95% confidence limits 3.65-6.14), over 24 h period. 4. In 15 patients in severe cardiac failure, urinary recovery of piretanide, over first 6 h, at the start of treatment was 21.2 +/- 2.1% while efficiency of the diuretic (mmol Na/mg drug) was 47.3 +/- 4.1. Long-term piretanide therapy was continued in the same group for up to and in some cases over 3 years. No other diuretics or potassium supplements were given. Piretanide dosage ranged from 6 to 24 mg day-1 according to clinical need. Plasma potassium fell significantly at 12 and 24 months, though remaining within the normal range. At these same times, significant elevations in both plasma urate and total fasting cholesterol were observed. Two patients developed overt gout on high dose piretanide therapy (24 mg day-1

  17. FACTS Devices Cost Recovery During Congestion Management in Deregulated Electricity Markets

    NASA Astrophysics Data System (ADS)

    Sharma, Ashwani Kumar; Mittapalli, Ram Kumar; Pal, Yash

    2016-09-01

    In future electricity markets, flexible alternating current transmission system (FACTS) devices will play key role for providing ancillary services. Since huge cost is involved for the FACTS devices placement in the power system, the cost invested has to be recovered in their life time for the replacement of these devices. The FACTS devices in future electricity markets can act as an ancillary services provider and have to be remunerated. The main contributions of the paper are: (1) investment recovery of FACTS devices during congestion management such as static VAR compensator and unified power flow controller along with thyristor controlled series compensator using non-linear bid curves, (2) the impact of ZIP load model on the FACTS cost recovery of the devices, (3) the comparison of results obtained without ZIP load model for both pool and hybrid market model, (4) secure bilateral transactions incorporation in hybrid market model. An optimal power flow based approach has been developed for maximizing social welfare including FACTS devices cost. The optimal placement of the FACTS devices have been obtained based on maximum social welfare. The results have been obtained for both pool and hybrid electricity market for IEEE 24-bus RTS.

  18. Large-Scale Transportation Network Congestion Evolution Prediction Using Deep Learning Theory

    PubMed Central

    Ma, Xiaolei; Yu, Haiyang; Wang, Yunpeng; Wang, Yinhai

    2015-01-01

    Understanding how congestion at one location can cause ripples throughout large-scale transportation network is vital for transportation researchers and practitioners to pinpoint traffic bottlenecks for congestion mitigation. Traditional studies rely on either mathematical equations or simulation techniques to model traffic congestion dynamics. However, most of the approaches have limitations, largely due to unrealistic assumptions and cumbersome parameter calibration process. With the development of Intelligent Transportation Systems (ITS) and Internet of Things (IoT), transportation data become more and more ubiquitous. This triggers a series of data-driven research to investigate transportation phenomena. Among them, deep learning theory is considered one of the most promising techniques to tackle tremendous high-dimensional data. This study attempts to extend deep learning theory into large-scale transportation network analysis. A deep Restricted Boltzmann Machine and Recurrent Neural Network architecture is utilized to model and predict traffic congestion evolution based on Global Positioning System (GPS) data from taxi. A numerical study in Ningbo, China is conducted to validate the effectiveness and efficiency of the proposed method. Results show that the prediction accuracy can achieve as high as 88% within less than 6 minutes when the model is implemented in a Graphic Processing Unit (GPU)-based parallel computing environment. The predicted congestion evolution patterns can be visualized temporally and spatially through a map-based platform to identify the vulnerable links for proactive congestion mitigation. PMID:25780910

  19. How Travel Demand Affects Detection of Non-Recurrent Traffic Congestion on Urban Road Networks

    NASA Astrophysics Data System (ADS)

    Anbaroglu, B.; Heydecker, B.; Cheng, T.

    2016-06-01

    Occurrence of non-recurrent traffic congestion hinders the economic activity of a city, as travellers could miss appointments or be late for work or important meetings. Similarly, for shippers, unexpected delays may disrupt just-in-time delivery and manufacturing processes, which could lose them payment. Consequently, research on non-recurrent congestion detection on urban road networks has recently gained attention. By analysing large amounts of traffic data collected on a daily basis, traffic operation centres can improve their methods to detect non-recurrent congestion rapidly and then revise their existing plans to mitigate its effects. Space-time clusters of high link journey time estimates correspond to non-recurrent congestion events. Existing research, however, has not considered the effect of travel demand on the effectiveness of non-recurrent congestion detection methods. Therefore, this paper investigates how travel demand affects detection of non-recurrent traffic congestion detection on urban road networks. Travel demand has been classified into three categories as low, normal and high. The experiments are carried out on London's urban road network, and the results demonstrate the necessity to adjust the relative importance of the component evaluation criteria depending on the travel demand level.

  20. Spatial-Temporal Congestion Identification Based on Time Series Similarity Considering Missing Data.

    PubMed

    Qi, Hongsheng; Liu, Meiqi; Wang, Dianhai; Chen, Mengwei

    2016-01-01

    Traffic congestion varies spatially and temporally. The observation of the formation, propagation and dispersion of network traffic congestion can lead to insights about the network performance, the bottleneck dynamics etc. While many researchers use the traffic flow data to reconstruct the congestion profile, the data missing problem is bypassed. Current methods either omit the missing data or supplement the missing part by average etc. Great error may be introduced during these processes. Rather than simply discarding the missing data, this research regards the data missing event as a result of either the severe congestion which prevent the floating vehicle from entering the congested area, or a type of feature of the resulting traffic flow time series. Hence a new traffic flow operational index time series similarity measurement is expected to be established as a basis of identifying the dynamic network bottleneck. The method first measures the traffic flow operational similarity between pairs of neighboring links, and then the similarity results are used to cluster the spatial-temporal congestion. In order to get the similarity under missing data condition, the measurement is implemented in a two-stage manner: firstly the so called first order similarity is calculated given that the traffic flow variables are bounded both upside and downside; then the first order similarity is aggregated to generate the second order similarity as the output. We implement the method on part of the real-world road network; the results generated are not only consistent with empirical observation, but also provide useful insights.

  1. Does rush hour see a rush of emotions? Driver mood in conditions likely to exhibit congestion.

    PubMed

    Morris, Eric A; Hirsch, Jana A

    2016-09-01

    Polls show that a large portion of the public considers traffic congestion to be a problem and believes a number of policy interventions would ameliorate it. However, most of the public rejects new taxes and fees to fund these improvements. This may be because of a disconnect between the public's stated antipathy towards congestion and the recalled emotional costs congestion imposes. To explore this, we use a large and representative sample drawn from the American Time Use Survey to examine how drivers experience four emotions (happiness, sadness, stress, and fatigue), plus a constructed composite mood variable, when they travel in peak periods, in large cities, in city centers, and in combinations of these. We also explore the interactions between these indicators and trip duration. We find evidence that drivers in the largest cities at the very peak of rush hour (5:00pm-6:00pm) are in a less positive mood, presumably because of congestion. However, this effect, though significant, is small, and we find no significant results using broader definitions of the peak period. In all, our findings suggest that congestion's impact on drivers as a group is quite limited. This may help explain why the public's attitude toward painful financial trade-offs to address congestion is lukewarm.

  2. Large-scale transportation network congestion evolution prediction using deep learning theory.

    PubMed

    Ma, Xiaolei; Yu, Haiyang; Wang, Yunpeng; Wang, Yinhai

    2015-01-01

    Understanding how congestion at one location can cause ripples throughout large-scale transportation network is vital for transportation researchers and practitioners to pinpoint traffic bottlenecks for congestion mitigation. Traditional studies rely on either mathematical equations or simulation techniques to model traffic congestion dynamics. However, most of the approaches have limitations, largely due to unrealistic assumptions and cumbersome parameter calibration process. With the development of Intelligent Transportation Systems (ITS) and Internet of Things (IoT), transportation data become more and more ubiquitous. This triggers a series of data-driven research to investigate transportation phenomena. Among them, deep learning theory is considered one of the most promising techniques to tackle tremendous high-dimensional data. This study attempts to extend deep learning theory into large-scale transportation network analysis. A deep Restricted Boltzmann Machine and Recurrent Neural Network architecture is utilized to model and predict traffic congestion evolution based on Global Positioning System (GPS) data from taxi. A numerical study in Ningbo, China is conducted to validate the effectiveness and efficiency of the proposed method. Results show that the prediction accuracy can achieve as high as 88% within less than 6 minutes when the model is implemented in a Graphic Processing Unit (GPU)-based parallel computing environment. The predicted congestion evolution patterns can be visualized temporally and spatially through a map-based platform to identify the vulnerable links for proactive congestion mitigation.

  3. Effects of bucindolol on neurohormonal activation in congestive heart failure

    SciTech Connect

    Eichhorn, E.J.; McGhie, A.L.; Bedotto, J.B.; Corbett, J.R.; Malloy, C.R.; Hatfield, B.A.; Deitchman, D.; Willard, J.E.; Grayburn, P.A. )

    1991-01-01

    To examine the effects of beta-adrenergic blockade on neurohormonal activation in patients with congestive heart failure, 15 men had assessments of hemodynamics and supine peripheral renin and norepinephrine levels before and after 3 months of oral therapy with bucindolol, a nonselective beta antagonist. At baseline, plasma renin activity did not correlate with any hemodynamic parameter. However, norepinephrine levels had a weak correlation with left ventricular end-diastolic pressure (r = 0.74, p less than 0.01), stroke volume index (r = 0.61, p less than 0.02) and pulmonary vascular resistance (r = 0.54, p less than 0.05). Plasma renin decreased with bucindolol therapy, from 11.6 +/- 13.4 to 4.3 +/- 4.1 ng/ml/hour (mean +/- standard deviation; p less than 0.05), whereas plasma norepinephrine was unchanged, from 403 +/- 231 to 408 +/- 217 pg/ml. A wide diversity of the norepinephrine response to bucindolol was observed with reduction of levels in some patients and elevation in others. Although plasma norepinephrine did not decrease, heart rate tended to decrease (from 82 +/- 20 vs 73 +/- 11 min-1, p = 0.059) with beta-adrenergic blockade, suggesting neurohormonal antagonism at the receptor level. No changes in I-123 metaiodobenzylguanidine uptake occurred after bucindolol therapy, suggesting unchanged adrenergic uptake of norepinephrine with beta-blocker therapy. Despite reductions in plasma renin activity and the presence of beta blockade, the response of renin or norepinephrine levels to long-term bucindolol therapy did not predict which patients had improved in hemodynamic status (chi-square = 0.37 for renin, 0.82 for norepinephrine).

  4. Effects of desipramine on norepinephrine clearance in congestive heart failure

    SciTech Connect

    Clemson, B.; Baily, R.G.; Davis, D.; Zelis, R. )

    1990-08-01

    Elevated plasma norepinephrine (NE) in congestive heart failure (CHF) is caused by increased NE spillover and decreased NE clearance. To evaluate the effects of neuronal uptake blockade on NE clearance, we studied NE kinetics during steady-state infusions of (3H)NE, before and after oral desipramine (DMI, 50 mg) in 11 patients with CHF and 8 normal volunteers. Baseline plasma NE was greater in the CHF group (637 +/- 56 vs. 271 +/- 32 pg/ml; P less than 0.001), NE clearance was lower in CHF (1.31 +/- 0.21 vs. 1.94 +/- 0.17 l.min-1.m-2; P = 0.026), and NE spillover was greater in CHF (4.71 +/- 0.78 vs. 3.04 +/- 0.35 nmol.min-1.m-2, P = 0.054). After DMI, plasma NE rose significantly in CHF (778 +/- 67; P = 0.008), and NE clearance decreased further in CHF (0.97 +/- 0.16; P = 0.024), but neither changed in normal subjects. NE spillover did not change in either group. There appears to be an enhanced effect of DMI on NE clearance in CHF patients. Two general mechanisms may be responsible for this finding, an increased concentration of drug, possibly caused by a decreased volume of distribution, and an increased sensitivity of neuronal amine pumps to DMI. Both mechanisms may reflect a more general abnormality of clearance of drugs and hormones related to abnormalities of tissue perfusion in CHF.

  5. Rationale, design and organisation of an efficacy and safety study of oxypurinol added to standard therapy in patients with NYHA class III - IV congestive heart failure.

    PubMed

    Freudenberger, Ronald S; Schwarz, Richard P; Brown, Joanne; Moore, Alan; Mann, Douglas; Givertz, Michael M; Colucci, Wilson S; Hare, Joshua M

    2004-11-01

    Oxypurinol, the active metabolite of allopurinol and a potent xanthine oxidase inhibitor (XOI), is under evaluation as a novel agent for the treatment of congestive heart failure (HF). Several lines of evidence provide the rationale for the hypothesis that XOIs will improve clinical outcomes in patients with HF. First, XOIs have unique positive inotropic effects, improving myocardial contraction and performance while simultaneously improving myocardial energy metabolism. Second, XOIs ameliorate endothelial dysfunction in humans with HF. Finally, XO activity is upregulated in the heart and vasculature of subjects with HF, which may in turn contribute to oxidative stress and/or increased uric acid levels. Together these findings form the rationale for the Controlled Efficacy and Safety Study of Oxypurinol Added to Standard Therapy in Patients with New York Heart Association (NYHA) class III - IV Congestive Heart Failure (OPT-CHF) trial (Food and Drug Administration IND 65,125), a Phase II - III prospective, randomised, double-blind, placebo-controlled trial, which will include patients with stable symptomatic HF in NYHA class III - IV congestive HF who are deemed clinically stable on a standard and appropriately maximised heart failure therapy regimen. The efficacy end point for OPT-CHF is a composite that incorporates measures of patient outcome and well-being.

  6. National Ignition Facility (NIF) Control Network Design and Analysis

    SciTech Connect

    Bryant, R M; Carey, R W; Claybourn, R V; Pavel, G; Schaefer, W J

    2001-10-19

    The control network for the National Ignition Facility (NIF) is designed to meet the needs for common object request broker architecture (CORBA) inter-process communication, multicast video transport, device triggering, and general TCP/IP communication within the NIF facility. The network will interconnect approximately 650 systems, including the embedded controllers, front-end processors (FEPs), supervisory systems, and centralized servers involved in operation of the NIF. All systems are networked with Ethernet to serve the majority of communication needs, and asynchronous transfer mode (ATM) is used to transport multicast video and synchronization triggers. CORBA software infra-structure provides location-independent communication services over TCP/IP between the application processes in the 15 supervisory and 300 FEP systems. Video images sampled from 500 video cameras at a 10-Hz frame rate will be multicast using direct ATM Application Programming Interface (API) communication from video FEPs to any selected operator console. The Ethernet and ATM control networks are used to broadcast two types of device triggers for last-second functions in a large number of FEPs, thus eliminating the need for a separate infrastructure for these functions. Analysis, design, modeling, and testing of the NIF network has been performed to provide confidence that the network design will meet NIF control requirements.

  7. A case of severe hypoalbuminemia associated with chronic congestive heart failure: the role of the tricuspid regurgitation.

    PubMed

    Alexa, Ioana Dana; Ilie, Adina Carmen; Moroşanu, Anca; Crăcană, Irina; Onuţu, Ramona; Voica, Ana

    2014-01-01

    Hypoalbuminemia is considered an independent predictor of mortality, especially in elderly patients. It is common in patients with congestive heart failure, when is due to several mechanisms: increased volume of distribution, significant stasis in the mesenteric circulation and altered protein metabolism in the liver. These alterations are even more pregnant when tricuspid regurgitation is associated or aggravated by different risk factors (recent infections, anemia, hyperthyroidism). We present the case of an elderly patient with severe hypoproteinemia and important hypoalbuminemia associated with congestive heart failure and aggravation of tricuspid regurgitation. The differential diagnosis concluded that hypoalbuminemia was influenced by tricuspid regurgitation as it enhanced liver dysfunction and enteral protein absorption due to increased stasis in mesenteric system. On the other hand, hypoalbuminemia contributed to the progression of heart failure by favoring myocardial edema, volume overload, and diuretic resistance. This is why correct management of this situation should include removal of subclinical excess of fluid and renutrition. A multidisciplinary approach is needed in order to achieve a good control of the symptoms and a significant improvement of quality of life.

  8. Microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks

    NASA Astrophysics Data System (ADS)

    Kerner, Boris S.; Klenov, Sergey L.

    2003-09-01

    A microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks due to on-ramps, merge bottlenecks (a reduction of highway lanes), and off-ramps is presented. The basic postulate of three-phase traffic theory is used, which claims that homogeneous (in space and time) model solutions (steady states) of synchronized flow cover a two dimensional region in the flow-density plane [B. S. Kerner, Phys. Rev. Lett. 81, 3797 (1998); Trans. Res. Rec. 1678, 160 (1999)]. Phase transitions leading to diverse congested patterns, pattern evolution, and pattern nonlinear features have been found. Diagrams of congested patterns, i.e., regions of the pattern emergence dependent on traffic demand, have been derived. Diverse effects of metastability with respect to the pattern formation have been found. The microscopic theory allows us to explain the main empirical pattern features at on-ramps and off-ramps which have recently been found [B. S. Kerner, Phys. Rev. E 65, 046138 (2002)]. (i) Rather than moving jams, synchronized flow first occurs at bottlenecks if the flow rate is slowly increasing. Wide moving jams can spontaneously occur only in synchronized flow. (ii) General patterns (GP) and synchronized flow patterns (SP) can spontaneously emerge at the bottlenecks. There can be the widening SP (WSP), the moving SP (MSP), and the localized SP. (iii) At on-ramps cases of “weak” and “strong” congestion should be distinguished. In contrast to weak congestion, under strong congestion the flow rate in synchronized flow in GP reaches a limit flow rate, the frequency of the moving jam emergence reaches a maximum, i.e., the GP characteristics under strong congestion do not depend on traffic demand. (iv) At the off-ramp GP with weak congestion occur. (v) A study of the pattern formation on a highway with two bottlenecks shows that diverse expanded patterns can occur, which cover both bottlenecks. SP first emerged at the downstream bottleneck can be caught

  9. Evaluation of the public health impacts of traffic congestion: a health risk assessment

    PubMed Central

    2010-01-01

    Background Traffic congestion is a significant issue in urban areas in the United States and around the world. Previous analyses have estimated the economic costs of congestion, related to fuel and time wasted, but few have quantified the public health impacts or determined how these impacts compare in magnitude to the economic costs. Moreover, the relative magnitudes of economic and public health impacts of congestion would be expected to vary significantly across urban areas, as a function of road infrastructure, population density, and atmospheric conditions influencing pollutant formation, but this variability has not been explored. Methods In this study, we evaluate the public health impacts of ambient exposures to fine particulate matter (PM2.5) concentrations associated with a business-as-usual scenario of predicted traffic congestion. We evaluate 83 individual urban areas using traffic demand models to estimate the degree of congestion in each area from 2000 to 2030. We link traffic volume and speed data with the MOBILE6 model to characterize emissions of PM2.5 and particle precursors attributable to congestion, and we use a source-receptor matrix to evaluate the impact of these emissions on ambient PM2.5 concentrations. Marginal concentration changes are related to a concentration-response function for mortality, with a value of statistical life approach used to monetize the impacts. Results We estimate that the monetized value of PM2.5-related mortality attributable to congestion in these 83 cities in 2000 was approximately $31 billion (2007 dollars), as compared with a value of time and fuel wasted of $60 billion. In future years, the economic impacts grow (to over $100 billion in 2030) while the public health impacts decrease to $13 billion in 2020 before increasing to $17 billion in 2030, given increasing population and congestion but lower emissions per vehicle. Across cities and years, the public health impacts range from more than an order of

  10. Microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks.

    PubMed

    Kerner, Boris S; Klenov, Sergey L

    2003-09-01

    A microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks due to on-ramps, merge bottlenecks (a reduction of highway lanes), and off-ramps is presented. The basic postulate of three-phase traffic theory is used, which claims that homogeneous (in space and time) model solutions (steady states) of synchronized flow cover a two dimensional region in the flow-density plane [B. S. Kerner, Phys. Rev. Lett. 81, 3797 (1998); Trans. Res. Rec. 1678, 160 (1999)]. Phase transitions leading to diverse congested patterns, pattern evolution, and pattern nonlinear features have been found. Diagrams of congested patterns, i.e., regions of the pattern emergence dependent on traffic demand, have been derived. Diverse effects of metastability with respect to the pattern formation have been found. The microscopic theory allows us to explain the main empirical pattern features at on-ramps and off-ramps which have recently been found [B. S. Kerner, Phys. Rev. E 65, 046138 (2002)]. (i) Rather than moving jams, synchronized flow first occurs at bottlenecks if the flow rate is slowly increasing. Wide moving jams can spontaneously occur only in synchronized flow. (ii) General patterns (GP) and synchronized flow patterns (SP) can spontaneously emerge at the bottlenecks. There can be the widening SP (WSP), the moving SP (MSP), and the localized SP. (iii) At on-ramps cases of "weak" and "strong" congestion should be distinguished. In contrast to weak congestion, under strong congestion the flow rate in synchronized flow in GP reaches a limit flow rate, the frequency of the moving jam emergence reaches a maximum, i.e., the GP characteristics under strong congestion do not depend on traffic demand. (iv) At the off-ramp GP with weak congestion occur. (v) A study of the pattern formation on a highway with two bottlenecks shows that diverse expanded patterns can occur, which cover both bottlenecks. SP first emerged at the downstream bottleneck can be caught at the

  11. Ephedrine QoS: an antidote to slow, congested, bufferless NoCs.

    PubMed

    Fang, Juan; Yao, Zhicheng; Sui, Xiufeng; Bao, Yungang

    2014-01-01

    Datacenters consolidate diverse applications to improve utilization. However when multiple applications are colocated on such platforms, contention for shared resources like networks-on-chip (NoCs) can degrade the performance of latency-critical online services (high-priority applications). Recently proposed bufferless NoCs (Nychis et al.) have the advantages of requiring less area and power, but they pose challenges in quality-of-service (QoS) support, which usually relies on buffer-based virtual channels (VCs). We propose QBLESS, a QoS-aware bufferless NoC scheme for datacenters. QBLESS consists of two components: a routing mechanism (QBLESS-R) that can substantially reduce flit deflection for high-priority applications and a congestion-control mechanism (QBLESS-CC) that guarantees performance for high-priority applications and improves overall system throughput. We use trace-driven simulation to model a 64-core system, finding that, when compared to BLESS, a previous state-of-the-art bufferless NoC design, QBLESS, improves performance of high-priority applications by an average of 33.2% and reduces network-hops by an average of 42.8%.

  12. Pelvic congestion syndrome and left renal compression syndrome - clinical features and therapeutic approaches.

    PubMed

    Jeanneret, Christina; Beier, Konstantin; von Weymarn, Alexander; Traber, Jürg

    2016-01-01

    Knowledge of the anatomy of the pelvic, gonadal and renal veins is important to understand pelvic congestion syndrome (PCS) and left renal vein compression syndrome (LRCS), which is also known as the nutcracker syndrome. LRCS is related to PCS and to the presence of vulvar, vaginal and pudendal varicose veins. The diagnosis of the two syndromes is difficult, and usually achieved with CT- or phlebography. The gold standard is the intravenous pressure measurement using conventional phlebography. The definition of PCS is described as pelvic pain, aggravated in the standing position and lasting for more than 6 months. Pain in the left flank and microhaematuria is seen in patients with LRCS. Women with multiple pregnancies are at increased risk of developing varicose vein recurrences with pelvic drainage and ovarian vein reflux after crossectomy and stripping of the great saphenous vein. The therapeutic options are: conservative treatment (medroxyprogesteron) or interventional (coiling of the ovarian vein) or operative treatment (clipping of the ovarian vein). Controlled prospective trials are needed to find the best treatment.

  13. Transcatheter Ovarian Vein Embolization Using Coils for the Treatment of Pelvic Congestion Syndrome

    SciTech Connect

    Kwon, Se Hwan; Oh, Joo Hyeong Ko, Kyung Ran; Park, Ho Chul; Huh, Joo Yup

    2007-07-15

    Purpose. To evaluate the therapeutic effectiveness of ovarian vein embolization using coils for pelvic congestion syndrome (PCS), a common cause of chronic pelvic pain in multiparous women. Methods. Between November 1998 and June 2005, 67 patients were diagnosed with PCS and underwent ovarian vein coil embolization. Through medical records and telephone interviews, the pre-embolization pain level and post-embolization pain control were assessed. In addition, in those cases where pain persisted after embolization or where patients were dissatisfied with the procedure, additional treatments and subsequent changes in pain scores were also analyzed. Evaluation after coil embolization was performed within 3-6 months (n = 3), 6 months to 1 year (n 7), 1-2 years (n = 13), 2-3 years (n = 7), 3-4 years (n = 7), 4-5 years (n 13), or 5-6 years (n = 17). Results. Among a total of 67 patients, 82% (55/67) experienced pain reduction after coil embolization, were satisfied with the procedure, and did not pursue any further treatment. Twelve patients (18%, 12/67) responded that their pain level had not changed, or had become more severe. Among them, 9 patients were treated surgically and the remaining 3 patients remained under continuous drug therapy. Conclusion. Ovarian vein embolization using coils is a safe and effective therapeutic method for treatment of PCS. It is thought that surgical treatment should be considered in cases where embolization proves ineffective.

  14. Integrative Medical Care Plus Mindfulness Training for Patients With Congestive Heart Failure: Proof of Concept.

    PubMed

    Kemper, Kathi J; Carmin, Cheryl; Mehta, Bella; Binkley, Phillip

    2016-10-01

    Congestive heart failure (CHF) has a high rate of morbidity and mortality. It is often accompanied by other medical and psychosocial comorbidities that complicate treatment and adherence. We conducted a proof of concept pilot project to determine the feasibility of providing integrative group medical visits plus mindfulness training for patients recently discharged with CHF. Patients were eligible if they had been discharged from an inpatient stay for CHF within the 12 months prior to the new program. The Compassionate Approach to Lifestyle and Mind-Body (CALM) Skills for Patients with CHF consisted of 8 weekly visits focusing on patient education about medications, diet, exercise, sleep, and stress management; group support; and training in mind-body skills such as mindfulness, self-compassion, and loving-kindness. Over two 8-week sessions, 8/11 (73%) patients completed at least 4 visits. The patients had an average age of 57 years. The most common comorbidities were weight gain, sleep problems, and fatigue. After the sessions, 100% of patients planned to make changes to their diet, exercise, and stress management practices. Over half of the patients who met with a pharmacist had a medication-related problem. Improvements were observed in depression, fatigue, and satisfaction with life. Integrative group visits focusing on healthy lifestyle, support, and skill-building are feasible even among CHF patients and should be evaluated in controlled trials as a patient-centered approach to improving outcomes related to improving medication management, depression, fatigue, and quality of life.

  15. Immunosuppressive therapy in patients with congestive cardiomyopathy and myocardial uptake of Gallium-67

    SciTech Connect

    O'Connell, J.B.; Robinson, J.A.; Henkin, R.E.; Gunnar, R.M.

    1981-10-01

    Thirty-nine patients with idiopathic congestive cardiomyopathy underwent gallium-67 scintigraphy. Twenty had no evidence of myocardial uptake (group I) and 19 had demonstrable myocardial gallium-67 activity (group II). There was no significant difference in age, sex, duration of symptoms, antecedent viral illness, left ventricular end-diastolic pressure, pulmonary artery systolic pressure, or ejection fraction between the two groups. Fifteen patients in group II were treated with prednisone and azathioprine for a minimum of 8 months. Nine of 15 patients were clinically unchanged and gallium-67 scans remained positive (group IIa). Six patients had significant improvement and resolution of myocardial gallium-67 uptake (group IIb). The mean change in ejection fraction was +0.2% in group I, -4.8% in Group IIa, and +13.8% in group IIb. There were five deaths in group I (25% mortality), three in group IIa (33% mortality), and no deaths in group IIb. The only significant difference between patients in group IIa and those in group IIb was a greater left ventricular posterior wall thickness in group IIa patients. Twenty control patients without cardiac disease had negative gallium-67 scans. We conclude that gallium-67 myocardial scintigraphy may be a useful test for predicting the response to prednisone and azathioprine therapy.

  16. Immunosuppressive therapy in patients with congestive cardiomyopathy and myocardial uptake of gallium-67

    SciTech Connect

    O'Connell, J.B.; Robinson, J.A.; Henkin, R.E.; Gunnar, R.M.

    1981-10-01

    Thirty-nine patients with idiopathic congestive cardiomyopathy underwent gallium-67 scintigraphy. Twenty had no evidence of myocardial uptake (group I) and 19 had demonstrable myocardial gallium-67 activity (group II). There was no significant difference in age, sex, duration of symptoms, antecedent viral illness, left ventricular end-diastolic pressure, pulmonary artery systolic pressure, or ejection fraction between the two groups. Fifteen patients in group II were treated with prednisone and azathioprine for a minimum of 8 months. Nine of 15 patients were clinically unchanged and gallium-67 scans remained positive (group IIa). Six patients had significant improvement and resolution of myocardial gallium-67 uptake (group IIb). The mean change in ejection fraction was +0.2% in group I, -4.8% in Group IIa, and +13.8% in group IIb. There were five deaths in group I (25% mortality), three in group IIa (33% mortality), and no deaths in group IIb. The only significant difference between patients in group IIa and those in group IIb was a greater left ventricular posterior wall thickness in group IIa patients. Twenty control patients without cardiac disease had negative gallium-67 scans. We conclude that gallium-67 myocardial scintigraphy may be a useful test for predicting the response to prednisone and azathioprine therapy.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Integer-Linear-Programing Optimization in Scalable Video Multicast with Adaptive Modulation and Coding in Wireless Networks

    PubMed Central

    Lee, Chaewoo

    2014-01-01

    The advancement in wideband wireless network supports real time services such as IPTV and live video streaming. However, because of the sharing nature of the wireless medium, efficient resource allocation has been studied to achieve a high level of acceptability and proliferation of wireless multimedia. Scalable video coding (SVC) with adaptive modulation and coding (AMC) provides an excellent solution for wireless video streaming. By assigning different modulation and coding schemes (MCSs) to video layers, SVC can provide good video quality to users in good channel conditions and also basic video quality to users in bad channel conditions. For optimal resource allocation, a key issue in applying SVC in the wireless multicast service is how to assign MCSs and the time resources to each SVC layer in the heterogeneous channel condition. We formulate this problem with integer linear programming (ILP) and provide numerical results to show the performance under 802.16 m environment. The result shows that our methodology enhances the overall system throughput compared to an existing algorithm. PMID:25276862

  19. Integer-linear-programing optimization in scalable video multicast with adaptive modulation and coding in wireless networks.

    PubMed

    Lee, Dongyul; Lee, Chaewoo

    2014-01-01

    The advancement in wideband wireless network supports real time services such as IPTV and live video streaming. However, because of the sharing nature of the wireless medium, efficient resource allocation has been studied to achieve a high level of acceptability and proliferation of wireless multimedia. Scalable video coding (SVC) with adaptive modulation and coding (AMC) provides an excellent solution for wireless video streaming. By assigning different modulation and coding schemes (MCSs) to video layers, SVC can provide good video quality to users in good channel conditions and also basic video quality to users in bad channel conditions. For optimal resource allocation, a key issue in applying SVC in the wireless multicast service is how to assign MCSs and the time resources to each SVC layer in the heterogeneous channel condition. We formulate this problem with integer linear programming (ILP) and provide numerical results to show the performance under 802.16 m environment. The result shows that our methodology enhances the overall system throughput compared to an existing algorithm.

  20. On the Efficiency of the New York Independent System OperatorMarket for Transmission Congestion Contracts

    SciTech Connect

    Siddiqui, Afzal S.; Bartholomew, Emily S.; Marnay, Chris; Oren,Shmuel S.

    2003-04-01

    The physical nature of electricity generation and deliverycreates special problems for the design of efficient markets, notably theneed to manage delivery in real time and the volatile congestion andassociated costs that result. Proposals for the operation of thederegulated electricity industry tend towards one of two paradigms:centralized and decentralized. Transmission congestion management can beimplemented in the more centralized point-to-point approach, a in NewYork state, where derivative transmission congestion contracts (TCCs) aretraded, or in the more decentralized flowgate-based approach. While it iswidely accepted that theoretically TCCs have attractive properties ashedging instruments against congestion cost uncertainty, whetherefficient markets for them can be established in practice has beenquestioned. Based on an empirical analysis of publicly available datafrom years 2000 and 2001, it appears that New York TCCs providedmarketparticipants with a potentially effective hedge against volatilecongestion rents. However, the prices paid for TCCs systematicallydiverged from the resulting congestion rents for distant locations and athigh prices. The price paid for the hedge not being in line with thecongestion rents, i.e. unreasonably high risk premiums are being paid,suggests an inefficient market. The low liquidity of TCC markets and thedeviation of TCC feasibility requirements from actual energy flows arepossible explanations.

  1. Medicinal Leech Therapy for Glans Penis Congestion After Primary Bladder Exstrophy-Epispadias Repair in an Infant: A Case Report.

    PubMed

    Wagenheim, Gavin N; Au, Jason; Gargollo, Patricio C

    2016-01-01

    Many postoperative complications have been reported after repair of classic bladder exstrophy. We present a case of medicinal leech therapy for glans penis congestion following exstrophy repair in an infant. A 2-week-old male with classic bladder exstrophy underwent complete primary repair. On postoperative day 1, he developed rapidly worsening glans penis venous congestion. Medicinal leech therapy was instituted with antibiotics and blood transfusions to maintain a hematocrit >30%. After 24 hours, venous congestion improved and therapy was discontinued. The patient's remaining hospital course was uncomplicated. Medicinal leeches are an effective therapy to relieve glans penis venous congestion.

  2. Administration of tolvaptan with reduction of loop diuretics ameliorates congestion with improving renal dysfunction in patients with congestive heart failure and renal dysfunction.

    PubMed

    Hanatani, Akihisa; Shibata, Atsushi; Kitada, Ryouko; Iwata, Shinichi; Matsumura, Yoshiki; Doi, Atsushi; Sugioka, Kenichi; Takagi, Masahiko; Yoshiyama, Minoru

    2017-03-01

    In patients with congestive heart failure and renal dysfunction, high dose of diuretics are necessary to improve congestion, which may progress to renal dysfunction. We examined the efficacy of tolvaptan with reduction of loop diuretics to improve renal function in patients with congestive heart failure and renal dysfunction. We conducted a multicenter, prospective, randomized study in 44 patients with congestive heart failure and renal dysfunction (serum creatinine concentration ≥1.1 mg/dl) treated with conventional diuretics. Patients were randomly divided into two groups: tolvaptan (15 mg) with a fixed dose of diuretics or with reducing to a half-dose of diuretics for 7-14 consecutive days. We examined the change of urine volume, body weight, serum creatinine and electrolyte concentrations in each group. Both groups demonstrated significant urine volume increase (724 ± 176 ml/day in the fixed-dose group and 736 ± 114 ml/day in the half-dose group) and body weight reduction (1.6 ± 1.5 kg and 1.6 ± 1.9 kg, respectively) from baseline, with no differences between the two groups. Serum creatinine concentration was significantly increased in the fixed-dose group (from 1.60 ± 0.47 to 1.74 ± 0.66 mg/dl, p = 0.03) and decreased in the half-dose group (from 1.98 ± 0.91 to 1.91 ± 0.97 mg/dl, p = 0.10). So the mean changes in serum creatinine concentration from baseline significantly differed between the two groups (0.14 ± 0.08 mg/dl in the fixed-dose group and -0.07 ± 0.19 mg/dl in the half-dose group, p = 0.006). The administration of tolvaptan with reduction of loop diuretics was clinically effective to ameliorate congestion with improving renal function in patients with congestive heart failure and renal dysfunction.

  3. Inflammatory Biomarkers in Refractory Congestive Heart Failure Patients Treated with Peritoneal Dialysis.

    PubMed

    Kunin, Margarita; Carmon, Vered; Arad, Michael; Levin-Iaina, Nomy; Freimark, Dov; Holtzman, Eli J; Dinour, Dganit

    2015-01-01

    Proinflammatory cytokines play a pathogenic role in congestive heart failure. In this study, the effect of peritoneal dialysis treatment on inflammatory cytokines levels in refractory congestive heart failure patients was investigated. During the treatment, the patients reached a well-tolerated edema-free state and demonstrated significant improvement in NYHA functional class. Brain natriuretic peptide decreased significantly after 3 months of treatment and remained stable at 6 months. C-reactive protein, a plasma marker of inflammation, decreased significantly following the treatment. Circulating inflammatory cytokines TNF-α and IL-6 decreased significantly after 3 months of peritoneal dialysis treatment and remained low at 6 months. The reduction in circulating inflammatory cytokines levels may be partly responsible for the efficacy of peritoneal dialysis for refractory congestive heart failure.

  4. Traffic Cellular Automata Simulation of a Congested Round-About in Mauritius

    NASA Astrophysics Data System (ADS)

    Fowdur, S. C.; Rughooputh, S. D. D. V.

    In this paper a Traffic Cellular Automata (TCA) simulation of a highly congested round-about in Mauritius is performed. The simulations are performed using a multi-cell model that includes anticipation and probability randomization. The simulation model is first calibrated to match actual traffic count statistics taken at the round-about. The topology of the round-about is then modified and the TCA model is used to predict the impact on the congestion level of different changes made. The simulation results enable the assessment of the impact on the traffic density and travel time of the different modifications made. It has been found that the construction of a flyover bridge at the round-about will be the most convenient solution to alleviate congestion and improve the flux significantly.

  5. Biventricular pacing in congestive heart failure: a boost toward finer living.

    PubMed

    Luck, Jerry C; Wolbrette, Deborah L; Boehmer, John P; Ulsh, Paula J; Silber, David; Naccarelli, Gerald V

    2002-01-01

    With 550,000 new cases each year, congestive heart failure is a major medical problem. Several medical therapies, including digoxin, angiotensin-converting enzyme inhibitors, and beta-blockers, have reduced the number of re-hospitalizations and slowed the progression of congestive heart failure. Angiotensin-converting enzyme inhibitors, some beta-blockers, and the combination of hydralazine with nitrates have improved survival. Despite these benefits, medical therapy frequently fails to improve quality of life. Biventricular pacing has been introduced to resynchronize mechanical and electrical asynchrony frequently observed in patients with heart failure. The most recent pacing trials show an improvement in quality of life and functional class. Long-term data are needed to determine the effect of biventricular pacing on survival. The acute hemodynamic studies suggest that resynchronization pacing therapy may predict a positive long-term benefit for many patients with congestive heart failure.

  6. Pericardial and pleural effusions in congestive heart failure-anatomical, pathophysiologic, and clinical considerations.

    PubMed

    Natanzon, Alex; Kronzon, Itzhak

    2009-09-01

    Transudative pleural and pericardial effusions are not uncommon in patients with congestive heart failure. Pericardial effusion forms only with elevation of the right-sided filling pressure in the heart. In patients with biventricular failure, there is no evidence that elevated left-sided pressure, in the absence of elevated right-sided pressure, can cause a pericardial effusion. Pleural effusion forms with acute elevation of the right-sided or the left-sided filling pressure in the heart. In patients with congestive heart failure, elevated right-sided filling pressures are less common than elevated left-sided filling pressures, thus, explaining a lower prevalence of pericardial than pleural effusions. Pleural effusions in patients with congestive heart failure are typically bilateral. However, a unilateral pleural effusion is more commonly seen on the right side. Although multiple theories attempt to explain the right-sided preponderance of pleural effusion, to date, no mechanism has been universally accepted or experimentally proven.

  7. Surveying traffic congestion based on the concept of community structure of complex networks

    NASA Astrophysics Data System (ADS)

    Ma, Lili; Zhang, Zhanli; Li, Meng

    2016-07-01

    In this paper, taking the traffic of Beijing city as an instance, we study city traffic states, especially traffic congestion, based on the concept of network community structure. Concretely, using the floating car data (FCD) information of vehicles gained from the intelligent transport system (ITS) of the city, we construct a new traffic network model which is with floating cars as network nodes and time-varying. It shows that this traffic network has Gaussian degree distributions at different time points. Furthermore, compared with free traffic situations, our simulations show that the traffic network generally has more obvious community structures with larger values of network fitness for congested traffic situations, and through the GPSspg web page, we show that all of our results are consistent with the reality. Then, it indicates that network community structure should be an available way for investigating city traffic congestion problems.

  8. Haemodynamic response to peripheral venous congestion in patients with unexplained recurrent syncope.

    PubMed

    Bellard, Elisabeth; Fortrat, Jacques-Olivier; Dupuis, Jean-Marc; Victor, Jacques; Lefthériotis, Georges

    2003-09-01

    In patients with recurrent unexplained syncope, exaggerated peripheral venous pooling and impaired circulatory adjustment is thought to contribute to the outcome of a head-up tilt (HUT) test. The present study investigated the role of leg volume changes during venous congestion in the haemodynamic response of patients with recurrent unexplained syncope and the ability to predict the outcome of a HUT test. Changes in calf volume (strain gauge plethysmography), heart rate and arterial blood pressure were recorded in 60 patients with history of unexplained syncope (without postural tachycardia symptom) during venous congestion provoked by pneumatic thigh cuffs while supine at rest and during the initial 10 min of a 45 min 70 degrees HUT test. Twenty-seven patients [age (mean+/-S.D.), 39+/-16 years] exhibited symptoms [HUT(+)] and 33 patients (45+/-14 years) were asymptomatic [HUT(-)]. During venous congestion, mean+/-S.E.M. calf volume increased in both groups [HUT(-), 4.5+/-0.2; HUT(+), 4.8+/-0.4 ml x 100 ml(-1), not significant), but significantly less during head-upright tilt [HUT(-), 3.3+/-0.2, P <0.01; HUT(+), 2.6+/-0.3 ml x 100 ml(-1), P <0.001] without differences between the groups. During venous congestion, arterial pressure increased significantly in asymptomatic HUT(-) patients, but not in the HUT(+) patients. Calf volume changes did not correlate with a symptomatic outcome to a 70 degrees HUT. The lack of exaggerated venous pooling during venous congestion and the inability of calf volume changes to predict a positive HUT suggest that excessive venous pooling does not contribute to the outcome of HUT. Attenuated changes in arterial pressure during venous congestion while supine suggest impaired adjustment of peripheral resistance to leg venous occlusion.

  9. Study on Congestion and Bursting in Small-World Networks with Time Delay from the Viewpoint of Nonlinear Dynamics

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Liu, Li-Guang; Wang, Hang

    2012-06-01

    The small-world network model represented by a set of evolution equations with time delay is used to investigate the nonlinear dynamics of networks, and the nature of instability phenomena in traffic, namely, congestion and bursting in the networks, are studied and explained from bifurcation analysis. Then, the governing equation in the vector field is further reduced into a map, and the ensuing period-doubling bifurcation, sequence of period-doubling bifurcation and period-3 are studied intuitively. The existence of chaos is verified numerically. In particular, the influences of time delay on the nonlinear dynamics are presented. The results show that there are a rich variety of nonlinear dynamics related to the intermittency of the traffic flows in the system, and the results can gain a fundamental understanding of the instability in the networks, and the time delay can be used as a key parameter in the control of the systems.

  10. Outcomes for patients with congestive heart failure in a nursing case management model.

    PubMed

    Morrison, R S; Beckworth, V

    1998-01-01

    Congestive heart failure is a leading cause of hospital admissions, costing an estimated $7 billion in 1990. Hospital-based nursing case management has been used to reduce costs of care while maintaining quality of care. This study describes the outcomes for 50 patients with congestive heart failure in a hospital-based nursing care management model, providing general outcomes, physiologic status, physical functioning, health knowledge, and family caregiver status. The number of medications was the only predictor of length of stay using regression analysis.

  11. State of the science: posthospitalization nursing interventions in congestive heart failure.

    PubMed

    Hamner, Jenny B

    2005-01-01

    Nursing's role as key healthcare providers who give emotional support and teach self-care to patients with congestive heart failure has evolved substantially in recent years. The purpose of this article is to provide a systematic evaluation of the impact of posthospital nursing interventions in the management of heart failure. Four models of nursing interventions emerged: home-based nursing interventions, multidisciplinary interventions, heart failure clinics, and telephone- or technology-based nursing interventions. On the basis of currently available data, posthospital nursing interventions in congestive heart failure can improve clinical outcomes and decrease healthcare costs and resource use.

  12. The economics of time shared computing: Congestion, user costs and capacity

    NASA Technical Reports Server (NTRS)

    Agnew, C. E.

    1982-01-01

    Time shared systems permit the fixed costs of computing resources to be spread over large numbers of users. However, bottleneck results in the theory of closed queueing networks can be used to show that this economy of scale will be offset by the increased congestion that results as more users are added to the system. If one considers the total costs, including the congestion cost, there is an optimal number of users for a system which equals the saturation value usually used to define system capacity.

  13. Common variants in IL-17A/IL-17RA axis contribute to predisposition to and progression of congestive heart failure

    PubMed Central

    Sandip, Chaugai; Tan, Lun; Huang, Jin; Li, Qing; Ni, Li; Cianflone, Katherine; Wang, Dao Wen

    2016-01-01

    Abstract Heart failure is characterized by immune activation leading to production and release of proinflammatory cytokines. Interleukin 17A (IL-17A) is a proinflammatory cytokine and multiple lines of evidence from animal and human studies suggest crucial roles of IL-17A in heart failure. Therefore, we investigated whether common polymorphisms of genes IL17A and IL17RA (coding interleukin 17 receptor A) contribute to genetic predisposition to heart failure and adverse clinical outcomes associated with it. A total of 1713 adult patients with congestive heart failure and 1713 age- and sex-matched controls were genotyped for promoter single nucleotide polymorphisms (SNPs), rs2275913 and rs8193037 in IL17A and rs4819554 in IL17RA, to assess the relationship between individual SNPs and the risk of congestive heart failure. Results showed that rs8193037 in IL17A was associated with the risk of congestive heart failure (odds ratio [OR] = 0.76; 95% confidence interval [CI] 0.63–0.90, adjusted P = 0.002) after adjustment for multiple cardiovascular risk factors including age, sex, smoking status, diabetes, hypertension, and dyslipidemia. This association was evident in both ischemic and nonischemic heart failure (P = 0.005 and P = 0.05, respectively). Furthermore, prospective follow-up of 12.7 months for the occurrence of adverse clinical outcomes showed that rs4819554 in IL17RA was significantly associated with cardiovascular mortality (hazard ratio [HR] = 1.28; 95% CI = 1.02–1.59, adjusted P = 0.03) after adjustments for multiple cardiovascular risk factors and New York Heart Association functional class. This study demonstrated associations of rs8193037 in the promoter of IL17A with the risk of congestive heart failure, and of rs4819554 in the promoter of IL17RA with the risk of cardiovascular mortality in patients with congestive heart failure. These data lend further support to the notion that immune activation and genetic polymorphisms contribute to heart failure

  14. Common variants in IL-17A/IL-17RA axis contribute to predisposition to and progression of congestive heart failure.

    PubMed

    Sandip, Chaugai; Tan, Lun; Huang, Jin; Li, Qing; Ni, Li; Cianflone, Katherine; Wang, Dao Wen

    2016-07-01

    Heart failure is characterized by immune activation leading to production and release of proinflammatory cytokines. Interleukin 17A (IL-17A) is a proinflammatory cytokine and multiple lines of evidence from animal and human studies suggest crucial roles of IL-17A in heart failure. Therefore, we investigated whether common polymorphisms of genes IL17A and IL17RA (coding interleukin 17 receptor A) contribute to genetic predisposition to heart failure and adverse clinical outcomes associated with it.A total of 1713 adult patients with congestive heart failure and 1713 age- and sex-matched controls were genotyped for promoter single nucleotide polymorphisms (SNPs), rs2275913 and rs8193037 in IL17A and rs4819554 in IL17RA, to assess the relationship between individual SNPs and the risk of congestive heart failure. Results showed that rs8193037 in IL17A was associated with the risk of congestive heart failure (odds ratio [OR] = 0.76; 95% confidence interval [CI] 0.63-0.90, adjusted P = 0.002) after adjustment for multiple cardiovascular risk factors including age, sex, smoking status, diabetes, hypertension, and dyslipidemia. This association was evident in both ischemic and nonischemic heart failure (P = 0.005 and P = 0.05, respectively). Furthermore, prospective follow-up of 12.7 months for the occurrence of adverse clinical outcomes showed that rs4819554 in IL17RA was significantly associated with cardiovascular mortality (hazard ratio [HR] = 1.28; 95% CI = 1.02-1.59, adjusted P = 0.03) after adjustments for multiple cardiovascular risk factors and New York Heart Association functional class.This study demonstrated associations of rs8193037 in the promoter of IL17A with the risk of congestive heart failure, and of rs4819554 in the promoter of IL17RA with the risk of cardiovascular mortality in patients with congestive heart failure. These data lend further support to the notion that immune activation and genetic polymorphisms contribute to heart failure pathogenesis

  15. The Nitric Oxide Donor Pentaerythritol Tetranitrate Reduces Platelet Activation in Congestive Heart Failure

    PubMed Central

    Flierl, Ulrike; Fraccarollo, Daniela; Widder, Julian D.; Micka, Jan; Neuser, Jonas; Bauersachs, Johann; Schäfer, Andreas

    2015-01-01

    Background Platelet activation associated with endothelial dysfunction and impaired endogenous platelet inhibition is part of the cardiovascular phenotype of congestive heart failure (CHF) and contributes to the increased risk for thromboembolic complications. Pentaerythritol tetranitrate (PETN) has been shown to release nitric oxide without development of nitrate tolerance. We investigated the effect of chronic PETN treatment on platelet activation and aggregation in an experimental CHF model. Methods and Results Chronic ischemic heart failure was induced in male Wistar rats by coronary artery ligation. Starting 7 days thereafter, rats were randomised to placebo or PETN (80 mg/kg twice daily). After 9 weeks, activation of circulating platelets was determined measuring platelet bound fibrinogen, which requires activated glycoprotein IIb/IIIa on the platelet surface. Binding was quantified by flow-cytometry using a FITC-labelled anti-fibrinogen antibody. Platelet-bound fibrinogen was significantly increased in CHF-Placebo (mean fluorescence intensity: Sham 88±4, CHF-Placebo 104±6, p<0.05) and reduced following treatment with PETN (89±7, p<0.05 vs. CHF-Placebo). Maximal and final ADP-induced aggregation was significantly enhanced in CHF-Placebo vs. Sham-operated animals and normalized / decreased following chronic PETN treatment. Moreover, platelet adhesion was significantly reduced (number of adherent platelets: control: 85.6±5.5, PETN: 40±3.3; p<0.001) and VASP phosphorylation significantly enhanced following in vitro PETN treatment. Conclusion Chronic NO supplementation using PETN reduces platelet activation in CHF rats. Thus, PETN may constitute a useful approach to prevent thromboembolic complications in CHF. PMID:25928879

  16. Peritoneal Dialysis in Patients with Refractory Congestive Heart Failure: A Systematic Review

    PubMed Central

    Lu, Renhua; Muciño-Bermejo, María-Jimena; Ribeiro, Leonardo Claudino; Tonini, Enrico; Estremadoyro, Carla; Samoni, Sara; Sharma, Aashish; Zaragoza Galván, José de Jesús; Crepaldi, Carlo; Brendolan, Alessandra; Ni, Zhaohui; Rosner, Mitchell H.; Ronco, Claudio

    2015-01-01

    Background Refractory congestive heart failure (RCHF) is associated with a high mortality rate and is a major contributor to hospital admissions. Peritoneal dialysis (PD) is an option to control volume overload and perhaps improve outcomes in this challenging patient population. The aim of this systematic review is to describe the relative risk-benefit ratio based on data reported regarding the use of PD in RCHF. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. An electronic search of PubMed, Embase, and the Cochrane Library was performed to identify relevant studies published from January 1951 to February 2014. Eligible studies selected were prospective or retrospective adult population studies on PD in the setting of RCHF. The following clinical outcomes were used to assess PD therapy: (1) hospitalization rates; (2) heart function; (3) renal function; (4) fluid overload, and (5) adverse clinical outcomes. Summary Of 864 citations, we excluded 843 citations and included 21 studies (n = 673 patients). After PD, hospitalization days declined significantly (p = 0.0001), and heart function improved significantly (left ventricular ejection fraction: p = 0.0013; New York Heart Association classification: p = 0.0000). There were no statistically significant differences in glomerular filtration rate after PD treatment in non-chronic kidney disease stage 5D patients (p = 0.1065). Among patients treated with PD, body weight decreased significantly (p = 0.0006). The yearly average peritonitis rate was 14.5%, and the average yearly mortality was 20.3%. Key Messages This systematic review suggests that PD may be an effective and safe therapeutic tool for patients with RCHF. PMID:25999963

  17. Change in nasal congestion index after treatment in patients with chronic rhinosinusitis with nasal polyposis

    PubMed Central

    Sahin-Onder, Serap; Oysu, Cagatay; Deveci, Ildem; Sahin, Samil; Aktas, Betul

    2016-01-01

    Background: The management of chronic rhinosinusitis with nasal polyposis (CRSwNP) involves both surgical and medical approaches, and remains a controversial subject. Objective: The objective of this prospective, randomized, controlled trial was to compare the medical and surgical treatments of CRSwNP in terms of their effect on the nasal congestion index (NCI). Methods: Forty-eight patients with CRSwNP were randomized either to medical or surgical therapy. Pretreatment and 3- and 6-month posttreatment assessments of the visual analog scale score, the 20-Item Sino-Nasal Outcome Test, saccharine clearance time, nasal endoscopy, and NCI measurement with acoustic rhinometry were performed. Forty-one subjects were included in the analysis. Results: Both the medical and surgical interventions for CRSwNP resulted in significant improvement in the visual analog scale score, 20-Item Sino-Nasal Outcome Test, saccharine clearance time, and nasal endoscopic examination scores. There was no difference between the two groups in terms of the percentage change from baseline for any of the parameters at the 6-month posttreatment assessment. NCI showed no significant difference from baseline. Similarly, no significant difference was found between the medical and surgical groups in terms of their effect on the NCI (p > 0.05). Conclusion: Because NCI does not correlate with standard subjective measures in outcomes for this group of patients, it cannot be used as an outcome measurement of treatment of subjects with CRSwNP. Results of this prospective randomized study did not find any additional benefit of surgical therapy over medical therapy in subjects with CRSwNP.

  18. Chronic Pelvic Pain due to Pelvic Congestion Syndrome: The Role of Diagnostic and Interventional Radiology

    SciTech Connect

    Ganeshan, Arul; Upponi, Sara; Hon, Lye-Quen; Uthappa, M. C.; Warakaulle, Dinuke R.; Uberoi, Raman

    2007-11-15

    Chronic pelvic pain (CPP) is a common cause of gynecologic referral. Pelvic congestion syndrome, which is said to occurs due to ovarian vein incompetence, is a recognized cause of CPP. The aim of this paper is to briefly describe the clinical manifestations, and to review the role of diagnostic and interventional radiology in the management of this probably under-diagnosed condition.

  19. Bootstrapping Results of Exercise Therapy and Education for Patients with Congestive Heart Failure

    ERIC Educational Resources Information Center

    Witta, E. Lea; Brubaker, Craig

    2003-01-01

    When studies are conducted over a period of time, the sample size typically decreases. In a study of the effects of exercise therapy and education with recovering congestive heart failure (CHF) patients (Brubaker, Witta, & Angelopoulus, 2003), the sample size decreased from over 40 to 9 participants after an 18-month time span. Although the…

  20. Post-Acute Home Care and Hospital Readmission of Elderly Patients with Congestive Heart Failure

    ERIC Educational Resources Information Center

    Li, Hong; Morrow-Howell, Nancy; Proctor, Enola K.

    2004-01-01

    After inpatient hospitalization, many elderly patients with congestive heart failure (CHF) are discharged home and receive post-acute home care from informal (family) caregivers and formal service providers. Hospital readmission rates are high among elderly patients with CHF, and it is thought that use of informal and formal services may reduce…

  1. The Impact of Family Functioning on Caregiver Burden among Caregivers of Veterans with Congestive Heart Failure

    ERIC Educational Resources Information Center

    Moore, Crystal Dea

    2010-01-01

    A cross-sectional study of 76 family caregivers of older veterans with congestive heart failure utilized the McMaster model of family functioning to examine the impact of family functioning variables (problem solving, communication, roles, affective responsiveness, and affective involvement) on caregiver burden dimensions (relationship burden,…

  2. Political and Public Acceptability of Congestion Pricing: Ideology and Self-Interest

    ERIC Educational Resources Information Center

    Harsman, Bjorn; Quigley, John M.

    2010-01-01

    Studies of the "stated preferences" of households generally report public and political opposition by urban commuters to congestion pricing. It is thought that this opposition inhibits or precludes tolls and pricing systems that would enhance efficiency in the use of scarce roadways. This paper analyzes the only case in which road…

  3. Congestion at Card and Book Catalogs--A Queuing Theory Approach.

    ERIC Educational Resources Information Center

    Bookstein, Abraham

    The question of whether a library's catalog should consist of cards arranged in a single alphabetical order (the "dictionary catalog) or be segregated as a separate file is discussed. Development is extended to encompass related problems involved in the creation of a book catalog. A model to study the effects of congestion at the catalog is…

  4. The Physics of Traffic Congestion and Road Pricing in Transportation Planning

    NASA Astrophysics Data System (ADS)

    Levinson, David

    2010-03-01

    This presentation develops congestion theory and congestion pricing theory from its micro- foundations, the interaction of two or more vehicles. Using game theory, with a two- player game it is shown that the emergence of congestion depends on the players' relative valuations of early arrival, late arrival, and journey delay. Congestion pricing can be used as a cooperation mechanism to minimize total costs (if returned to the players). The analysis is then extended to the case of the three- player game, which illustrates congestion as a negative externality imposed on players who do not themselves contribute to it. A multi-agent model of travelers competing to utilize a roadway in time and space is presented. To realize the spillover effect among travelers, N-player games are constructed in which the strategy set includes N+1 strategies. We solve the N-player game (for N = 7) and find Nash equilibria if they exist. This model is compared to the bottleneck model. The results of numerical simulation show that the two models yield identical results in terms of lowest total costs and marginal costs when a social optimum exists. Moving from temporal dynamics to spatial complexity, using consistent agent- based techniques, we model the decision-making processes of users and infrastructure owner/operators to explore the welfare consequence of price competition, capacity choice, and product differentiation on congested transportation networks. Component models include: (1) An agent-based travel demand model wherein each traveler has learning capabilities and unique characteristics (e.g. value of time); (2) Econometric facility provision cost models; and (3) Representations of road authorities making pricing and capacity decisions. Different from small-network equilibrium models in prior literature, this agent- based model is applicable to pricing and investment analyses on large complex networks. The subsequent economic analysis focuses on the source, evolution

  5. Wind power development in the United States: Effects of policies and electricity transmission congestion

    NASA Astrophysics Data System (ADS)

    Hitaj, Claudia

    In this dissertation, I analyze the drivers of wind power development in the United States as well as the relationship between renewable power plant location and transmission congestion and emissions levels. I first examine the role of government renewable energy incentives and access to the electricity grid on investment in wind power plants across counties from 1998-2007. The results indicate that the federal production tax credit, state-level sales tax credit and production incentives play an important role in promoting wind power. In addition, higher wind power penetration levels can be achieved by bringing more parts of the electricity transmission grid under independent system operator regulation. I conclude that state and federal government policies play a significant role in wind power development both by providing financial support and by improving physical and procedural access to the electricity grid. Second, I examine the effect of renewable power plant location on electricity transmission congestion levels and system-wide emissions levels in a theoretical model and a simulation study. A new renewable plant takes the effect of congestion on its own output into account, but ignores the effect of its marginal contribution to congestion on output from existing plants, which results in curtailment of renewable power. Though pricing congestion removes the externality and reduces curtailment, I find that in the absence of a price on emissions, pricing congestion may in some cases actually increase system-wide emissions. The final part of my dissertation deals with an econometric issue that emerged from the empirical analysis of the drivers of wind power. I study the effect of the degree of censoring on random-effects Tobit estimates in finite sample with a particular focus on severe censoring, when the percentage of uncensored observations reaches 1 to 5 percent. The results show that the Tobit model performs well even at 5 percent uncensored observations

  6. Central and peripheral quadriceps fatigue in congestive heart failure☆

    PubMed Central

    Hopkinson, Nicholas S.; Dayer, Mark J.; Antoine-Jonville, Sophie; Swallow, Elisabeth B.; Porcher, Raphael; Vazir, Ali; Poole-Wilson, Philip; Polkey, Michael I.

    2013-01-01

    Aims The clinical syndrome of heart failure includes exercise limitation that is not directly linked to measures of cardiac function. Quadriceps fatigability may be an important component of this and this may arise from peripheral or central factors. Methods and results We studied 10 men with CHF and 10 healthy age-matched controls. Compared with a rest condition, 10 min after incremental maximal cycle exercise, twitch quadriceps force in response to supramaximal magnetic femoral nerve stimulation fell in both groups (CHF 14.1% ± 18.1%, p = 0.037; Control: 20.8 ± 11.0%, p < 0.001; no significant difference between groups). There was no significant change in quadriceps maximum voluntary contraction voluntary force. The difference in the motor evoked potential (MEP) response to transcranial magnetic stimulation of the motor cortex between rest and exercise conditions at 10 min, normalised to the peripheral action potential, also fell significantly in both groups (CHF: 27.3 ± 38.7%, p = 0.037; Control: 41.1 ± 47.7%, p = 0.024). However, the fall in MEP was sustained for a longer period in controls than in patients (p = 0.048). Conclusions The quadriceps is more susceptible to fatigue, with a similar fall in TwQ occurring in CHF patients at lower levels of exercise. This is associated with no change in voluntary activation but a lesser degree of depression of quadriceps motor evoked potential. PMID:22795722

  7. A Study of the Effects of Congestion Information and a Priority Boarding Pass in a Theme Park with Multi-Agents

    NASA Astrophysics Data System (ADS)

    Tone, Tetsuya; Kohara, Kazuhiro

    We have investigated ways to reduce congestion in a theme park with multi-agents. We constructed a theme park model called Digital Park 1.0 with twenty-three attractions similar in form to Tokyo Disney Sea. We consider not only congestion information (number of vistors standing in line at each attraction) but also the advantage of a priority boarding pass, like Fast Pass which is used at Tokyo Disney Sea. The congestion-information-usage ratio, which reflects the ratio of visitors who behave according to congestion information, was changed from 0% to 100% in both models, with and without priority boarding pass. The “mean stay time of visitors" is a measure of satisfaction. The smaller mean stay time, the larger degree of satisfaction. Here, a short stay time means a short wait time. The resluts of each simulation are averaged over ten trials. The main results are as follows. (1) When congestion-information-usage ratio increased, the mean stay time decreases. When 20% of visitors behaved according to congestion information, the mean stay time was reduced by 30%. (2) A priority boarding pass reduced congestion, and mean stay time was reduced by 15%. (3) When visitors used congestion information and a priority boarding pass, mean stay time was further reduced. When the congestion-information-usage ratio was 20%, mean stay time was reduced by 35%. (4) When congestion-information-usage ratio was over 50%, the congestion reduction effects reached saturation.

  8. Congestion analysis of pilgrims in Hajj and Umrah congregation using block matching and optical flow

    NASA Astrophysics Data System (ADS)

    Farooq, Sumaiyya; Khan, Shoab A.; Usman Akram, M.

    2017-01-01

    A novel method has been proposed to classify the motion of pilgrims with respect to congestion level in the holy mosque of Makkah. Millions of Muslims visit this mosque during Hajj and Umrah every year. A large number of security personnel is required to maintain the smooth flow of pilgrims in order to avert any catastrophe. Therefore, it is inevitable to design a computer aided system to reduce human effort. The proposed system pre-processes input images to segregate the moving shadows and pilgrims in order to nullify the false motion due to moving shadows. A hybrid method consisting of block matching and optical flow techniques has been used for the computation of motion vectors. Decision tree classifier is used on the number of motion vectors having non-zero magnitude. Experiments show that the proposed system has promising results yielding an accuracy of 90.58% for the congestion classification of pilgrims.

  9. Nationwide SIP Telephony Network Design to Prevent Congestion Caused by Disaster

    NASA Astrophysics Data System (ADS)

    Satoh, Daisuke; Ashitagawa, Kyoko

    We present a session initiation protocol (SIP) network design for a voice-over-IP network to prevent congestion caused by people calling friends and family after a disaster. The design increases the capacity of SIP servers in a network by using all of the SIP servers equally. It takes advantage of the fact that equipment for voice data packets is different from equipment for signaling packets in SIP networks. Furthermore, the design achieves simple routing on the basis of telephone numbers. We evaluated the performance of our design in preventing congestion through simulation. We showed that the proposed design has roughly 20 times more capacity, which is 57 times the normal load, than the conventional design if a disaster were to occur in Niigata Prefecture struck by the Chuetsu earthquake in 2004.

  10. Optimizing congestion and emissions via tradable credit charge and reward scheme without initial credit allocations

    NASA Astrophysics Data System (ADS)

    Zhu, Wenlong; Ma, Shoufeng; Tian, Junfang

    2017-01-01

    This paper investigates the revenue-neutral tradable credit charge and reward scheme without initial credit allocations that can reassign network traffic flow patterns to optimize congestion and emissions. First, we prove the existence of the proposed schemes and further decentralize the minimum emission flow pattern to user equilibrium. Moreover, we design the solving method of the proposed credit scheme for minimum emission problem. Second, we investigate the revenue-neutral tradable credit charge and reward scheme without initial credit allocations for bi-objectives to obtain the Pareto system optimum flow patterns of congestion and emissions; and present the corresponding solutions are located in the polyhedron constituted by some inequalities and equalities system. Last, numerical example based on a simple traffic network is adopted to obtain the proposed credit schemes and verify they are revenue-neutral.

  11. A possible mechanism for the progression of chronic renal disease and congestive heart failure.

    PubMed

    Re, Richard N

    2015-01-01

    Chronic neurologic diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as various forms of chronic renal disease and systolic congestive heart failure, are among the most common progressive degenerative disorders encountered in medicine. Each disease follows a nearly relentless course, albeit at varying rates, driven by progressive cell dysfunction and drop-out. The neurologic diseases are characterized by the progressive spread of disease-causing proteins (prion-like proteins) from cell to cell. Recent evidence indicates that cell autonomous renin angiotensin systems operate in heart and kidney, and it is known that functional intracrine proteins can also spread between cells. This then suggests that certain progressive degenerative cardiovascular disorders such as forms of chronic renal insufficiency and systolic congestive heart failure result from dysfunctional renin angiotensin system intracrine action spreading in kidney or myocardium.

  12. PPARdelta activation normalizes cardiac substrate metabolism and reduces right ventricular hypertrophy in congestive heart failure.

    PubMed

    Jucker, Beat M; Doe, Christopher P; Schnackenberg, Christine G; Olzinski, Alan R; Maniscalco, Kristeen; Williams, Carolyn; Hu, Tom C-C; Lenhard, Stephen C; Costell, Melissa; Bernard, Roberta; Sarov-Blat, Lea; Steplewski, Klaudia; Willette, Robert N

    2007-07-01

    Previously, it was shown that selective deletion of peroxisome proliferator activated receptor delta (PPARdelta) in the heart resulted in a cardiac lipotoxicity, hypertrophy, and heart failure. The aim of the present study was to determine the effects of chronic and selective pharmacological activation of PPARdelta in a model of congestive heart failure. PPARdelta-specific agonist treatment (GW610742X at 30 and 100 mg/kg/day for 6-9 weeks) was initiated immediately postmyocardial infarction (MI) in Sprague-Dawley rats. Magnetic resonance imaging/spectroscopy was used to assess cardiac function and energetics. A 1-(13)C glucose clamp was performed to assess relative cardiac carbohydrate versus fat oxidation. Additionally, cardiac hemodynamics and reverse-transcription polymerase chain reaction gene expression analysis was performed. MI rats had significantly reduced left ventricle (LV) ejection fractions and whole heart phosphocreatine/adenosine triphosphate ratio compared with Sham animals (reduction of 43% and 14%, respectively). However, GW610742X treatment had no effect on either parameter. In contrast, the decrease in relative fat oxidation rate observed in both LV and right ventricle (RV) following MI (decrease of 58% and 54%, respectively) was normalized in a dose-dependent manner following treatment with GW610742X. These metabolic changes were associated with an increase in lipid transport/metabolism target gene expression (eg, CD36, CPT1, UCP3). Although there was no difference between groups in LV weight or infarct size measured upon necropsy, there was a dramatic reduction in RV hypertrophy and lung congestion (decrease of 22-48%, P<0.01) with treatment which was associated with a >7-fold decrease (P<0.05) in aterial natriuretic peptide gene expression in RV. Diuretic effects were not observed with GW610742X. In conclusion, chronic treatment with a selective PPARdelta agonist normalizes cardiac substrate metabolism and reduces RV hypertrophy and pulmonary

  13. Distributed Channel Selection in CRAHNs with Heterogeneous Spectrum Opportunities: A Local Congestion Game Approach

    NASA Astrophysics Data System (ADS)

    Xu, Yuhua; Wu, Qihui; Wang, Jinlong; Min, Neng; Anpalagan, Alagan

    This letter investigates the problem of distributed channel selection in cognitive radio ad hoc networks (CRAHNs) with heterogeneous spectrum opportunities. Firstly, we formulate this problem as a local congestion game, which is proved to be an exact potential game. Then, we propose a spatial best response dynamic (SBRD) to rapidly achieve Nash equilibrium via local information exchange. Moreover, the potential function of the game reflects the network collision level and can be used to achieve higher throughput.

  14. RESTRICTIVE CARDIOMYOPATHY AND SECONDARY CONGESTIVE HEART FAILURE IN A MCDOWELL'S CARPET PYTHON (MORELIA SPILOTA MCDOWELLI).

    PubMed

    Schilliger, Lionel; Chetboul, Valérie; Damoiseaux, Cécile; Nicolier, Alexandra

    2016-12-01

    Echocardiography is an established and noninvasive diagnostic tool used in herpetologic cardiology. Various cardiac lesions have been previously described in reptiles with the exception of restrictive cardiomyopathy. In this case report, restrictive cardiomyopathy and congestive heart failure associated with left atrial and sinus venosus dilation were diagnosed in a 2-yr-old captive lethargic McDowell's carpet python ( Morelia spilota mcdowelli), based on echocardiographic, Doppler, and histopathologic examinations. This cardiomyopathy was also associated with thrombosis within the sinus venosus.

  15. Congestive heart failure patient monitoring using wearable Bio-impedance sensor technology.

    PubMed

    Seulki Lee; Squillace, Gabriel; Smeets, Christophe; Vandecasteele, Marianne; Grieten, Lars; de Francisco, Ruben; Van Hoof, Chris

    2015-08-01

    A new technique to monitor the fluid status of congestive heart failure (CHF) patients in the hospital is proposed and verified in a clinical trial with 8 patients. A wearable Bio-impedance (BioZ) sensor allows a continuous localized measurement which can be complement clinical tools in the hospital. Thanks to the multi-parametric approach and correlation analysis with clinical reference, BioZ is successfully shown as a promising parameter for continuous and wearable CHF patient monitoring application.

  16. Role of brain serotonin dysfunction in the pathophysiology of congestive heart failure.

    PubMed

    Li, Lei; Morimoto, Sachio; Take, Sachiko; Zhan, Dong-Yun; Du, Cheng-Kun; Wang, Yuan-Yuan; Fan, Xue-Li; Yoshihara, Tatsuya; Takahashi-Yanaga, Fumi; Katafuchi, Toshihiko; Sasaguri, Toshiyuki

    2012-12-01

    Inherited or non-inherited dilated cardiomyopathy (DCM) patients develop varied disease phenotypes leading to death after developing congestive heart failure (HF) or sudden death with mild or no overt HF symptoms, suggesting that environmental and/or genetic factors may modify the disease phenotype of DCM. In this study, we sought to explore unknown genetic factors affecting the disease phenotype of monogenic inherited human DCM. Knock-in mice bearing a sarcomeric protein mutation that causes DCM were created on different genetic backgrounds; BALB/c and C57Bl/6. DCM mice on the BALB/c background showed cardiac enlargement and systolic dysfunction and developed congestive HF before died. In contrast, DCM mice on the C57Bl/6 background developed no overt HF symptoms and died suddenly, although they showed considerable cardiac enlargement and systolic dysfunction. BALB/c mice have brain serotonin dysfunction due to a single nucleotide polymorphism (SNP) in tryptophan hydroxylase 2 (TPH2). Brain serotonin dysfunction plays a critical role in depression and anxiety and BALB/c mice exhibit depression- and anxiety-related behaviors. Since depression is common and associated with poor prognosis in HF patients, we examined therapeutic effects of anti-depression drug paroxetine and anti-anxiety drug buspirone that could improve the brain serotonin function in mice. Both drugs reduced cardiac enlargement and improved systolic dysfunction and symptoms of severe congestive HF in DCM mice on the BALB/c background. These results strongly suggest that genetic backgrounds involving brain serotonin dysfunction, such as TPH2 gene SNP, may play an important role in the development of congestive HF in DCM.

  17. Echocardiographic evaluation of cardiac dyssynchrony in patients with congestive heart failure.

    PubMed

    Qin, Chuan; Zhang, Li; Zhang, Zi-Ming; Wang, Bin; Ye, Zhou; Wang, Yong; Nanda, Navin C; Xie, Ming-Xing

    2016-06-01

    The present study investigated the application of echocardiography to evaluation of cardiac dyssynchrony in patients with congestive heart failure (CHF). A total of 348 consecutive CHF patients who were admitted for cardiac resynchronization (CRT) and presented with low ejection fraction (EF) and wide QRS duration were enrolled in this study, along with 388 healthy individuals. Dyssynchrony was assessed based on filling time ratio (FT/RR), left ventricular pre-ejection delay (PED), interventricular mechanical delay (IVMD), longitudinal opposing wall delay (LOWD) and radial septal to posterior wall delay (RSPWD). Response to CRT was defined as a ≥15% increase in EF. The results showed that FT/RR was decreased while PED, IVMD, LOWD and RSPWD were increased in the CHF group compared with the control group (P<0.01). In the CHF group, FT/RR was negatively correlated with the QRS duration, LV end-diastolic diameter (LVESd), LV end-diastolic volume (LVEDV) and LV end-systolic volume (LVESV) (P<0.01), but positively with the LVEF (P<0.01). Additionally, PED, IVMD, LOWD and RSPWD were positively correlated with the QRS duration, LVESd, LVEDV and LVESV (P<0.01), but negatively with the LVEF (P<0.01). The CHF group was divided into three subgroups according to the varying degrees of LVEF. FT/RR decreased successively from the LVEF-1 group to the LVEF-2 group to the LVEF-3 group, while the PED, IVMD, LOWD and RSPWD successively increased in the same order (P<0.01). The CHF group was divided into three subgroups according to the varying degrees of QRS duration, and FT/RR decreased successively in a sequence from the QRS-1 group to the QRS-2 group to the QRS-3 group, while the PED, IVMD, LOWD and RSPWD successively increased in the same order (P<0.01). Speckle tracking radial dyssynchrony ≥130 ms was predictive of an EF response in patients in QRS-1 group (78% sensitivity, 83% specificity), those in QRS-2 group (83% sensitivity, 77% specificity) and in QRS-3 group (89

  18. A new Doppler method of assessing left ventricular ejection force in chronic congestive heart failure.

    PubMed

    Isaaz, K; Ethevenot, G; Admant, P; Brembilla, B; Pernot, C

    1989-07-01

    A noninvasive method using Doppler echocardiography was developed to determine the force exerted by the left ventricle in accelerating the blood into the aorta. The value of this new Doppler ejection index in the assessment of left ventricular (LV) performance was tested in 36 patients with chronic congestive heart disease undergoing cardiac catheterization and in 11 age-matched normal control subjects. The 36 patients were subgrouped into 3 groups based on angiographic ejection fraction (LV ejection fraction greater than 60, 41 to 60 and less than or equal to 40%). According to Newton's second law of motion (force = mass X acceleration), the LV ejection force was derived from the product of the mass of blood ejected during the acceleration time with the mean acceleration undergone during that time. In patients with LV ejection fraction less than or equal to 40%, LV ejection force, peak aortic velocity and mean acceleration were severely depressed when compared with the other groups (p less than 0.001). In patients with LV ejection fraction of 41 to 60%, LV ejection force was significantly reduced (22 +/- 3 kdynes) when compared with normal subjects (29 +/- 5 kdynes, p = 0.002) and with patients with LV ejection fraction greater than 60% (29 +/- 7 kdynes, p = 0.009); peak velocity and mean acceleration did not differ between these 3 groups. The LV ejection force showed a good linear correlation with LV ejection fraction (r = 0.86) and a better power fit (r = 0.91). Peak aortic blood velocity and mean acceleration showed less good linear correlations with LV ejection fraction (r = 0.73 and r = 0.66, respectively). The mass of blood ejected during the acceleration time also showed a weak linear correlation with LV ejection fraction (r = 0.64). An LV ejection force less than 20 kdynes was associated with a depressed LV performance (LV ejection fraction less than 50%) with 91% sensitivity and 90% specificity. Thus, these findings suggest that LV ejection force is a new

  19. Exercise training in congestive heart failure: risks and benefits.

    PubMed

    Keteyian, Steven J

    2011-01-01

    After decades of concern about the safety and effectiveness of exercise training in patients with heart failure (HF) due to reduced ejection fraction, initial research demonstrated the feasibility and physiologic benefits associated with such an intervention. Subsequent controlled studies confirmed these results and suggested improved clinical outcomes as well. This review summarizes the findings from single-site and multisite trials and meta-analyses that addressed the effects of exercise training on exercise capacity and clinical outcomes. Conclusions from these studies indicate that exercise is safe, improves health status and exercise capacity, attenuates much of the abnormal physiology that develops with HF, and yields a modest reduction in clinical events. Future research needs to identify which patient subgroups might benefit the most, the optimal exercise dose needed to lessen disease-related symptoms and maximize clinical benefit, and the effects of exercise training in patients with HF and preserved ejection fraction.

  20. Preventing postoperative congestion in reverse pedicle digital island flaps when reconstructing composite tissue defects in the fingertip: a patient series.

    PubMed

    Matsuzaki, Hironori; Kouda, Hisao; Yamashita, Haruyoshi

    2012-01-01

    For reconstructing an injured fingertip, a reverse pedicle digital island flap can restore excellent function and appearance. However, postoperative flap congestion may lead to flap necrosis. We tested a method for dissecting the vascular pedicle to prevent congestion and to provide more reliable results. Between August 2002 and December 2010, we reconstructed 14 fingertips in 13 patients (average age, 43 years; range, 24 to 68 years; 9 men). Through a small zigzag incision, the digital artery and a 4-mm-wide subcutaneous venous network were elevated in retrograde fashion to facilitate venous drainage. All flaps healed completely without severe congestion or necrosis. Slight flexion contractures remained in the PIP (mean, 12°) and DIP (mean, 14°) joints. Our procedure is simpler and more reliable than other techniques, such as adding a narrow skin bridge to the pedicle or a venous anastomosis to prevent venous congestion, and it assures the survival of the flap.

  1. The effects of congestion charging on road traffic casualties: a causal analysis using difference-in-difference estimation.

    PubMed

    Li, Haojie; Graham, Daniel J; Majumdar, Arnab

    2012-11-01

    This paper aims to identify the impacts of the London congestion charge on road casualties within the central London charging zone. It develops a full difference-in-difference (DID) model that is integrated with generalized linear models, such as Poisson and Negative Binomial regression models. Covariates are included in the model to adjust for factors that violate the parallel trend assumption, which is critical in the DID model. The lower Bayesian Information Criterion value suggests that the full difference-in-difference model performs well in evaluating the relationship between road accidents and the London congestion charge as well as other socio-economic factors. After adjusting for a time trend and regional effects, the results show that the introduction of the London congestion charge has a significant influence on the incidence of road casualties. The congestion charge reduces the total number of car accidents, but is associated with an increase in two wheeled vehicle accidents.

  2. A novel distributed model of the heart under normal and congestive heart failure conditions.

    PubMed

    Ravanshadi, Samin; Jahed, Mehran

    2013-04-01

    Conventional models of cardiovascular system frequently lack required detail and focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the cardiovascular system. It utilizes noninvasive blood flow and pressure seed data and temporal cardiac muscle regional activity to predict the operation of the heart under normal and congestive heart failure conditions. The analysis considers specific regions of the heart, namely, base, mid and apex of left ventricle. The proposed method of parameter estimation for hydraulic electric analogy model is recursive least squares algorithm. Based on simulation results and comparison to clinical data, effect of congestive heart failure in the heart is quantified. Accumulated results for simulated ejection fraction percentage of the apex, mid and base regions of the left ventricle in congestive heart failure condition were 39 ± 6, 36 ± 9 and 38 ± 8, respectively. These results are shown to satisfactorily match those found through clinical measurements. The proposed analytical method can in effect be utilized as a preclinical and predictive tool for high-risk heart patients and candidates for heart transplant, assistive device and total artificial heart.

  3. Pregnancy rhinitis in Turkish women: Do gestational week, BMI and parity affect nasal congestion?

    PubMed Central

    Ulkumen, Burak; Ulkumen, Burcu Artunc; Pala, Halil Gursoy; Celik, Onur; Sahin, Nevin; Karaca, Gizem; Demirdag, Meltem

    2016-01-01

    Objective: To determine the cumulative incidence of pregnancy rhinitis along with prevalence in different trimesters and to find out whether gestational age, BMI and parity have any effect on pregnancy related nasal congestion. Methods: In the prospective protocol at the obstetrics outpatient clinic, 167 pregnant women were enrolled consecutively. According to exclusion criteria, 67 of them were excluded. Visual-Analogue-Scale (VAS), Nasal-Obstructive-Symptom-Evaluation (NOSE) scale and Discharge-Inflammation-Polyps/Oedema (DIP) scoring were utilized for diagnosis of pregnancy rhinitis. Besides, weight, length, age, parity and week of pregnancy were recorded. Results: Total prevalence of pregnancy rhinitis was 17.17% and cumulative incidence was 38.89%. Our study revealed significant relation of NOSE score with both gestational week (r=0.474, p=0.001) and BMI (r=0.301, p=0.003). VAS score was significantly related with gestational week (r=0.409, p=0.001) and BMI (r=0.270, p=0.007). DIP score was found to be correlated only with gestational week (r=0.375, p=0.001). Conclusion: Cumulative incidence of pregnancy rhinitis was 38.89%. Nasal congestion was significantly associated with BMI and gestational week. Patients should be informed about unfavorable fetal and maternal outcomes of pregnancy related nasal congestion which is triggered by obesity and excessive weight gain in pregnancy. PMID:27648046

  4. Evaluation of embolization for periuterine varices involving chronic pelvic pain secondary to pelvic congestion syndrome

    PubMed Central

    Siqueira, Flavio Meirelles; Monsignore, Lucas Moretti; Rosa-e-Silva, Julio Cesar; Poli-Neto, Omero Benedicto; de Castro-Afonso, Luis Henrique; Nakiri, Guilherme Seizem; Muglia, Valdair Francisco; Abud, Daniel Giansante

    2016-01-01

    OBJECTIVES: To evaluate the clinical response and success rate after periuterine varices embolization in patients with chronic pelvic pain secondary to pelvic congestion syndrome and to report the safety of endovascular treatment and its rate of complications. METHODS: Retrospective cohort of patients undergoing endovascular treatment of pelvic congestion syndrome in our department from January 2012 to November 2015. Data were analyzed based on patient background, imaging findings, embolized veins, rate of complications, and clinical response as indicated by the visual analog pain scale. RESULTS: We performed periuterine varices embolization in 22 patients during the study, four of which required a second embolization. Seventeen patients reported a reduction in pelvic pain after the first embolization and three patients reported a reduction in pelvic pain after the second embolization. Minor complications were observed in our patients, such as postural hypotension, postoperative pain, and venous perforation during the procedure, without clinical repercussion. CONCLUSION: Periuterine varices embolization in patients with chronic pelvic pain secondary to pelvic congestion syndrome appears to be an effective and safe technique. PMID:28076514

  5. Being a palliative nurse for persons with severe congestive heart failure in advanced homecare.

    PubMed

    Brännström, Margareta; Brulin, Christine; Norberg, Astrid; Boman, Kurt; Strandberg, Gunilla

    2005-12-01

    Advanced homecare for persons with congestive heart failure is a 'new' challenge for palliative nurses. The aim of this study is to illuminate the meaning of being a palliative nurse for persons with severe congestive heart failure in advanced homecare. Narrative interviews with 11 nurses were conducted, tape-recorded, and transcribed verbatim. A phenomenological-hermeneutic method was used to interpret the text. One meaning of being a palliative nurse is being firmly rooted and guided by the values of palliative culture. Being adaptable to the patient's way of life carries great weight. On one hand nurses live out this value, facilitating for the patients to live their everyday life as good as possible. Being a facilitator is revealed as difficult, challenging, but overall positive. On the other hand nurses get into a tight corner when values of palliative culture clash and do not correspond with the nurses interpretation of what is good for the person with congestive heart failure. Being in such a tight corner is revealed as frustrating and giving rise to feelings of inadequacy. Thus, it seems important to reflect critical on the values of palliative culture.

  6. [Intraoperative fluid therapy in infants with congestive heart failure due to intracranial pial arteriovenous fistula].

    PubMed

    Arroyo-Fernández, F J; Calderón-Seoane, E; Rodríguez-Peña, F; Torres-Morera, L M

    2016-05-01

    Pial arteriovenous fistula is a rare intracranial congenital malformation (0.1-1: 100,000). It has a high blood flow between one or more pial arteries and drains into the venous circulation. It is usually diagnosed during the childhood by triggering an intracranial hypertension and/or congestive heart failure due to left-right systemic shunt. It is a rare malformation with a complex pathophysiology. The perioperative anaesthetic management is not well established. We present a 6-month-old infant diagnosed with pial arteriovenous fistula with hypertension and congestive heart failure due to left-right shunt. He required a craniotomy and clipping of vascular malformation. Anaesthetic considerations in patients with this condition are a great challenge. It must be performed by multidisciplinary teams with experience in paediatrics. The maintenance of blood volume during the intraoperative course is very important. Excessive fluid therapy can precipitate a congestive heart failure or intracranial hypertension, and a lower fluid therapy may cause a tissue hypoxia due to the bleeding.

  7. Highly Dynamic and Adaptive Traffic Congestion Avoidance in Real-Time Inspired by Honey Bee Behavior

    NASA Astrophysics Data System (ADS)

    Wedde, Horst F.; Lehnhoff, Sebastian; van Bonn, Bernhard; Bay, Z.; Becker, S.; Böttcher, S.; Brunner, C.; Büscher, A.; Fürst, T.; Lazarescu, A. M.; Rotaru, E.; Senge, S.; Steinbach, B.; Yilmaz, F.; Zimmermann, T.

    Traffic congestions have become a major problem in metropolitan areas world-wide, within and between cities, to an extent where they make driving and transportation times largely unpredictable. Due to the highly dynamic character of congestion building and dissolving this phenomenon appears even to resist a formal treatment. Static approaches, and even more their global management, have proven counterproductive in practice. Given the latest progress in VANET technology and the remarkable commercially driven efforts like in the European C2C consortium, or the VSC Project in the US, allow meanwhile to tackle various aspects of traffic regulation through VANET communication. In this paper we introduce a novel, completely decentralized multi-agent routing algorithm (termed BeeJamA) which we have derived from the foraging behavior of honey bees. It is highly dynamic, adaptive, robust, and scalable, and it allows for both avoiding congestions, and minimizing traveling times to individual destinations. Vehicle guidance is provided well ahead of every intersection, depending on the individual speeds. Thus strict deadlines are imposed on, and respected by, the BeeJamA algorithm. We report on extensive simulation experiments which show the superior performance of BeeJamA over conventional approaches.

  8. [A rare cause of 2:1 atrioventricular block and congestive heart failure in preterm infants: Hypocalcemia].

    PubMed

    Azak, Emine; Tatar Aksoy, Hatice; Ünsal, Handan; Çetin, İbrahim İlker

    2017-01-01

    Atrioventricular (AV) block in the neonatal period is a rare disorder. It is frequently associated with underlying structural congenital heart disease and maternal lupus. Presently described is premature baby who developed 2:1 AV block and congestive heart failure due to hypocalcemia. Dramatic clinical improvement was observed following treatment of intravenous 10% calcium gluconate. Therefore, it is suggested that serum calcium level of newborns with AV block and congestive heart failure be measured.

  9. T-wave amplitude attenuation/augmentation in patients with changing edematous states: implications for patients with congestive heart failure.

    PubMed

    Madias, John E

    2007-01-01

    Since peripheral edema impacts the entire electrocardiographic curve, it was hypothesized that it would also affect T waves. The amplitude of T waves were measured in all electrocardiographic leads and a sum (SigmaT) was calculated in 28 patients with and 28 patients without peripheral edema (controls). For patients with peripheral edema, SigmaT on admission was 21.9+/-10.6 mm and SigmaT at peak weight was 8.3+/-6.3 mm (P=.0005). For patients with peripheral edema who subsequently lost weight, SigmaT at peak weight was 7.2+/-6.1 mm and SigmaT at the lowest weight was 14.1+/-12.2 (P=.006). For controls, SigmaT from admission and SigmaT from discharge were 24.4+/-16.9 mm and 24.7+/-15.7 mm (P=.82), respectively. Percent change (Delta%SigmaT) from admission to peak weight correlated with Delta% in weight (r=0.58; P=.001) and Delta% in the sum of QRS complexes (SigmaQRS) (r=0.71; P=.00005). Delta%SigmaT from peak weight to the lowest weight correlated with the corresponding Delta%SigmaQRS (r=0.65; P=.02). Changes in T waves with development and alleviation of peripheral edema mirror the changes shown by the QRS complexes and may be useful in the treatment of patients with congestive heart failure or other edematous states.

  10. Pathophysiological targets for beta-blocker therapy in congestive heart failure.

    PubMed

    Just, H

    1996-04-01

    The treatment of congestive heart failure has seen considerable changes: while treatment with diuretics, digitalis glycosides and vasodilators has remained the mainstay of therapy, recently neurohumeral inhibition has been developed as an important principle: ACE-inhibitors have been shown to significantly improve quality of life and exercise performance and to substantially reduce mortality. Beta-blockers have been employed with increasing success mainly in congestive heart failure due to dilated idiopathic cardiomyopathy, in which a significant improvement in symptoms and life expectancy has been demonstrated. However, the precise mechanisms by which beta-blockade improves congestive heart failure remain to be elucidated. In addition to direct sympathoadrenal inhibition, reduction of heart rate may also play a major role in the therapeutic efficacy of beta-blockade in congestive heart failure. In the normal human heart increase in heart rate is accompanied by an increase in myocardial contractile performance (Bowditch-Treppe phenomenon). In chronic heart failure the myocardium undergoes a phenotype change which includes alterations of the activity of enzymes regulating calcium homoeostasis. The sarcoplasmic reticulum calcium ATPase (SERCA) is depressed both in function, as well as in expression. At the same time the sarcolemmal sodium-calcium exchanger is increased both in function and in expression. The result is a characteristic change in calcium homoeostasis with decreased diastolic uptake of calcium into the sarcoplasmic reticulum with subsequently reduced calcium release during the next systole, resulting in reduced contractile performance. At the same time increased capacity of the sodium-calcium exchanger extrudes intracellular calcium ions to the extra-cellular space, thereby rendering these ions unavailable for the contractile cycle. A result of these, seemingly specific, phenotype changes is an alteration of the force/frequency relationship. Instead of

  11. Pulmonary Vascular Congestion: A Mechanism for Distal Lung Unit Dysfunction in Obesity

    PubMed Central

    Oppenheimer, Beno W.; Berger, Kenneth I.; Ali, Saleem; Segal, Leopoldo N.; Donnino, Robert; Katz, Stuart; Parikh, Manish; Goldring, Roberta M.

    2016-01-01

    Rationale Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways. Objectives We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response. Methods 54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC. Measurements and Main Results Mean age was 45±12 years; mean BMI was 44.8±7 kg/m2. Vital capacity was 88±13% predicted with reduction in functional residual capacity (58±12% predicted). Despite normal DLCO (98±18% predicted), VC was elevated (135±31% predicted) while DM averaged 94±22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p<0.001; r2 = 0.34, p<0.001). Cardiac output and index (cardiac output / body surface area) were directly related to DM/VC (r2 = 0.41, p<0.001; r2 = 0.19, p = 0.03). Subjects with lower DM/VC demonstrated a cardiac output that remained in the normal range despite presence of obesity. Conclusions Global dysfunction of the distal lung (alveolar membrane and distal airway) is associated with pulmonary vascular congestion and failure to achieve the high output state of obesity. Pulmonary vascular congestion and consequent fluid transudation and/or alterations in the

  12. A Rate-Based Congestion Control Algorithm for the SURAP 4 Packet Radio Architecture (SRNTN-72)

    DTIC Science & Technology

    1990-01-01

    resourcc Ihoe rluniher of oiitrofl 1.ms iteriton’, required to culsll’, Ihrotlihni K.,n the frder the 4lrithn 1 ofthe ntnih r of1 floss , n_ lum the...because it is easy to compute and yields acceptable values. although it tends to underestimate slightl the number of transmissions attributable to...in the figure. We have preferred to only plot this range to allow easy comparison between bits-per-second rations and packets-per-second rations. Both

  13. Embolization of Incompetent Pelvic Veins for the Treatment of Recurrent Varicose Veins in Lower Limbs and Pelvic Congestion Syndrome

    SciTech Connect

    Meneses, Luis Fava, Mario; Diaz, Pia; Andia, Marcelo; Tejos, Cristian; Irarrazabal, Pablo; Uribe, Sergio

    2013-02-15

    We present our experience with embolization of incompetent pelvic veins (IPV) in women with recurrence of varicose veins (VV) in lower limbs, as well as symptoms of pelvic congestion syndrome (PCS), after first surgery. In addition, we evaluated the effects of embolization in decreasing the symptoms of VV before surgery as well as its effects on PCS symptoms. We included 10 women who had consulted a vascular surgeon because of recurrent VV in lower limbs after surgery. All of these patients were included in the study because they also had symptoms of PCS, probably due to IPV. In patients who had confirmed IPV, we performed embolization before a second surgery. VV and PCS were assessed before and at 3 months after embolization (before the second surgery) using a venous clinical severity score (VCSS) and a visual analog pain scale (VAS), respectively. Patients were controlled between 3 and 6 months after embolization. Paired Student t test analysis was used for comparing data before and after embolization. Fifteen vein segments in 10 women were suitable for embolization. There was a significant (p < 0.001) decrease of VCSS after embolization, and recurrence of VV was not detected within a period of 6 months. There was also significant (p < 0.01) relief of chronic pelvic pain related to PCS evaluated using VAS at 3 months after embolization. Embolization decreases the risk of VV recurrence after surgery and also improves PCS symptoms in women with VV in lower limbs and IPV.

  14. A new approach to early diagnosis of congestive heart failure disease by using Hilbert-Huang transform.

    PubMed

    Altan, Gokhan; Kutlu, Yakup; Allahverdi, Novruz

    2016-12-01

    Congestive heart failure (CHF) is a degree of cardiac disease occurring as a result of the heart's inability to pump enough blood for the human body. In recent studies, coronary artery disease (CAD) is accepted as the most important cause of CHF. This study focuses on the diagnosis of both the CHF and the CAD. The Hilbert-Huang transform (HHT), which is effective on non-linear and non-stationary signals, is used to extract the features from R-R intervals obtained from the raw electrocardiogram data. The statistical features are extracted from instinct mode functions that are obtained applying the HHT to R-R intervals. Classification performance is examined with extracted statistical features using a multilayer perceptron neural network. The designed model classified the CHF, the CAD patients and a normal control group with rates of 97.83%, 93.79% and 100%, accuracy, specificity and sensitivity, respectively. Also, early diagnosis of the CHF was performed by interpretation of the CAD with a classification accuracy rate of 97.53%, specificity of 98.18% and sensitivity of 97.13%. As a result, a single system having the ability of both diagnosis and early diagnosis of CHF is performed by integrating the CAD diagnosis method to the CHF diagnosis method.

  15. Time allocation shifts and pollutant exposure due to traffic congestion: an analysis using the national human activity pattern survey.

    PubMed

    Zhang, Kai; Batterman, Stuart A

    2009-10-15

    Traffic congestion increases air pollutant exposures of commuters and urban populations due to the increased time spent in traffic and the increased vehicular emissions that occur in congestion, especially "stop-and-go" traffic. Increased time in traffic also decreases time in other microenvironments, a trade-off that has not been considered in previous time activity pattern (TAP) analyses conducted for exposure assessment purposes. This research investigates changes in time allocations and exposures that result from traffic congestion. Time shifts were derived using data from the National Human Activity Pattern Survey (NHAPS), which was aggregated to nine microenvironments (six indoor locations, two outdoor locations and one transport location). After imputing missing values, handling outliers, and conducting other quality checks, these data were stratified by respondent age, employment status and period (weekday/weekend). Trade-offs or time-shift coefficients between time spent in vehicles and the eight other microenvironments were then estimated using robust regression. For children and retirees, congestion primarily reduced the time spent at home; for older children and working adults, congestion shifted the time spent at home as well as time in schools, public buildings, and other indoor environments. Changes in benzene and PM(2.5) exposure were estimated for the current average travel delay in the U.S. (9 min day(-1)) and other scenarios using the estimated time shifts coefficients, concentrations in key microenvironments derived from the literature, and a probabilistic analysis. Changes in exposures depended on the duration of the congestion and the pollutant. For example, a 30 min day(-1) travel delay was determined to account for 21+/-12% of current exposure to benzene and 14+/-8% of PM(2.5) exposure. The time allocation shifts and the dynamic approach to TAPs improve estimates of exposure impacts from congestion and other recurring events.

  16. Blood urea nitrogen to creatinine ratio is associated with congestion and mortality in heart failure patients with renal dysfunction.

    PubMed

    Parrinello, Gaspare; Torres, Daniele; Testani, Jeffrey M; Almasio, Piero Luigi; Bellanca, Michele; Pizzo, Giuseppina; Cuttitta, Francesco; Pinto, Antonio; Butler, Javed; Paterna, Salvatore

    2015-12-01

    Renal dysfunction (RD) and venous congestion are related and common in heart failure (HF). Studies suggest that venous congestion may be the primary driver of RD in HF. In this study, we sought to investigate retrospectively the relationship between common measures of renal function with caval congestion and mortality among outpatients with HF and RD. We reviewed data from 103 HF outpatients (45 males, mean age 74 years, ejection fraction 41.8 ± 11.6 %) with estimated glomerular filtration rate (eGFR) of < 60 ml/min in a single centre. During an ambulatory visit, all patients underwent blood test and ultrasonography of the inferior vena cava (IVC). Caval congestion was defined as IVC with both dilatation and impaired collapsibility. The best values of renal metrics in predicting caval congestion were determined with receiver-operating characteristic analysis. The BUN/Cr ratio is moderately correlated with IVC expiratory maximum diameter (r = 0.31, p < 0.0007). In a multiple logistic regression model, BUN/Cr > 25.5 (adjusted OR 2.98, p 0.015) and eGFR ≤ 45.8 (adjusted OR 5.38, p 0.002) identify patients at risk for caval congestion; a BUN/Cr > 23.7 was the best predictor of impaired collapsibility (adjusted OR 4.41, p 0.001). a BUN/Cr > 25.5 (HR 2.19, 95 % CI 1.21-3.94, p < 0.001) and NYHA class 3 (HR 2.91, 95 % CI 1.60-5.31, p < 0.0005) were independent risk factors associated with all-cause death during a median follow-up of 31 months. In outpatients with HF and RD, a higher BUN/Cr and lower eGFR are reliable renal biomarkers for caval congestion. The BUN/Cr is associated with long-term mortality and may help to stratify HF severity.

  17. Sinus Congestion

    MedlinePlus

    ... yourself? About Stephen J. Schueler, M.D News Advertising How It Works FAQ for Consumers FAQ for Physicians Testimonials Site Map Terms of Use Contact Us FreeMD is provided for information purposes only and should not be used as a ...

  18. Congestive Hepatomegaly

    MedlinePlus

    ... or out of the liver? Gallstones Gluten intolerance Heart failure High blood pressure Am I Correct? More Videos News HealthDay Better Efforts Could Help Rid the U.S. of Hepatitis B, C: Report TUESDAY, March 28, 2017 (HealthDay News) -- Improved prevention, screening and treatment could ...

  19. The impact of directed choice on the design of preventive healthcare facility network under congestion.

    PubMed

    Vidyarthi, Navneet; Kuzgunkaya, Onur

    2015-12-01

    Preventive healthcare (PH) programs and services aim at reducing the likelihood and severity of potentially life-threatening illness by early detection and prevention. The effectiveness of these programs depends on the participation level and the accessibility of the users to the facilities providing the services. Factors that impact the accessibility include the number, type, and location of the facilities as well as the assignment of the clients to these facilities. In this paper, we study the impact of system-optimal (i.e., directed) choice on the design of the preventive healthcare facility network under congestion. We present a model that simultaneously determines the location and the size of the facilities as well as the allocation of clients to these facilities so as to minimize the weighted sum of the total travel time and the congestion associated with waiting and service delay at the facilities. The problem is set up as a network of spatially distributed M/G/1 queues and formulated as a nonlinear mixed integer program. Using simple transformation of the nonlinear objective function and piecewise linear approximation, we reformulate the problem as a linear model. We present a cutting plane algorithm based exact (-optimal) solution approach. We analyze the tradeoff between travel time and queuing time and its impact on the location and capacity of the facilities as well as the allocation of clients to these facilities under a directed choice policy. We present a case study that deals with locating mammography clinics in Montreal, Canada. The results show that incorporating congestion in the PH facility network design substantially reduces the total time spent by clients. The proposed model allows policy makers to direct clients to facilities in an equitable manner resulting in better accessibility.

  20. Transport growth in Bangkok: Energy, environment, and traffic congestion. Workshop proceedings

    SciTech Connect

    Philpott, J.

    1995-07-01

    Bangkok, the capital of Thailand, is a physically and economically complexcity with a complicated transport system. With daily traffic congestion averaging 16 hours, the air quality is such that to breathe street level pollution for 8 eight hours is roughly equivalent to smoking nine cigarettes per day. Estimates suggest idling traffic costs up to $1.6 billion annually. Energy use within the transport sector is on a steady rise with an estimated increase in 11 years of two and one half times. Severe health impacts have begun to effect many residents - young children and the elderly being particularly vulnerable. Bangkok`s air quality and congestion problems are far from hopeless. Great potential exists for Bangkok to remedy its transport-related problems. The city has many necessary characteristics that allow an efficient, economical system of transport. For example, its high density level makes the city a prime candidate for an efficient system of mass transit and the multitude and close proximity of shops, street vendors, restaurants, and residential areas is highly conducive to walking and cycling. Technical knowledge and capacity to devise and implement innovative policies and projects to address air quality and congestion problems is plentiful. There is also consensus among Bangkokians that something needs to be done immediately to clear the air and the roads. However, little has been done. This report proposes a new approach to transport planning for Bangkok that integrates consideration of ecological, social, and financial viability in the process of making decisions regarding managing existing infrastructure and investments in new infrastructure. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  1. Congestive heart failure in 6 African grey parrots (Psittacus e erithacus).

    PubMed

    Juan-Sallés, C; Soto, S; Garner, M M; Montesinos, A; Ardiaca, M

    2011-05-01

    Six African grey parrots (Psittacus e erithacus) were diagnosed with cardiomyopathy and congestive heart failure based on gross and microscopic findings. Ages ranged from 15 days to 8 years, and 5 of 6 parrots were either neonates or juveniles at the time of diagnosis. Two neonates and 2 juveniles came from the same breeding aviary; the 2 juveniles were born to the same breeding pair. The 2 other parrots were kept as pets. Clinical signs included distention of the coelomic cavity (4 of 6), rales (3 of 6), weakness (4 of 6), bradyarrhythmia (1 of 6), growth retardation (1 of 6), crop stasis (1 of 6), and regurgitation (1 of 6). Three parrots were euthanized and 3 died. Gross findings included cardiomegaly due to biventricular, right-, or left-sided cardiomyopathy (6 of 6); coelomic effusion (6 of 6); whitish or yellow foci in the liver (6 of 6); atrophy of the liver (particularly, the left lobe; 5 of 6); reddened or grey lungs (5 of 6); subcutaneous edema (2 of 6); hydropericardium (1 of 6); and bilateral thyroid gland enlargement (1 of 6). Relevant microscopic findings included passive hepatic congestion (6 of 6) and pulmonary congestion (2 of 6), lymphocytic thyroiditis (2 of 6), and diffuse thyroid follicular hyperplasia (2 of 6). Microscopically, the heart was unremarkable (2 of 6) or had mild lymphocytic myocarditis (2 of 6), mild multifocal cytoplasmic vacuolation of cardiomyocytes (2 of 6), mild lymphocytic myocardial (Purkinje cell) ganglioneuritis (1 of 6), and mild multifocal interstitial fibrosis and nuclear hypertrophy of cardiomyocytes (1 of 6). One parrot had concurrent proventricular dilatation disease (systemic ganglioneuritis). The cause of cardiomyopathy in these parrots was not determined.

  2. Parameter optimization in AQM controller design to support TCP traffic

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Yang, Oliver W.

    2004-09-01

    TCP congestion control mechanism has been widely investigated and deployed on Internet in preventing congestion collapse. We would like to employ modern control theory to specify quantitatively the control performance of the TCP communication system. In this paper, we make use of a commonly used performance index called the Integral of the Square of the Error (ISE), which is a quantitative measure to gauge the performance of a control system. By applying the ISE performance index into the Proportional-plus-Integral controller based on Pole Placement (PI_PP controller) for active queue management (AQM) in IP routers, we can further tune the parameters for the controller to achieve an optimum control minimizing control errors. We have analyzed the dynamic model of the TCP congestion control under this ISE, and used OPNET simulation tool to verify the derived optimized parameters of the controllers.

  3. Evaluation of public opinion about congestion pricing and tolls. Final research report

    SciTech Connect

    Ulberg, C.; MacFarland, G.

    1995-09-01

    The two primary objectives of the research were (1) to assess public attitudes in the Puget Sound Region toward tolls, congestion pricing, and other forms of market-based transportation pricing (e.g., gas taxes, VMT charges, parking fees) and (2) to explore various ways to present information to the public so that people will feel adequately informaed to decide whether to support pricing system. A third objective that developed out of early research stages was to measure how the level of acceptance of pricing changes (for or against) as understanding increases.

  4. Congestive kidney failure in cardiac surgery: the relationship between central venous pressure and acute kidney injury.

    PubMed

    Gambardella, Ivancarmine; Gaudino, Mario; Ronco, Claudio; Lau, Christopher; Ivascu, Natalia; Girardi, Leonard N

    2016-11-01

    Acute kidney injury (AKI) in cardiac surgery has traditionally been linked to reduced arterial perfusion. There is ongoing evidence that central venous pressure (CVP) has a pivotal role in precipitating acute renal dysfunction in cardiac medical and surgical settings. We can regard this AKI driven by systemic venous hypertension as 'kidney congestive failure'. In the cardiac surgery population as a whole, when the CVP value reaches the threshold of 14 mmHg in postoperative period, the risk of AKI increases 2-fold with an odds ratio (OR) of 1.99, 95% confidence interval (95% CI) of 1.16-3.40. In cardiac surgery subsets where venous hypertension is a hallmark feature, the incidence of AKI is higher (tricuspid disease 30%, carcinoid valve disease 22%). Even in the non-chronically congested coronary artery bypass population, CVP measured 6 h postoperatively showed significant association to renal failure: risk-adjusted OR for AKI was 5.5 (95% CI 1.93-15.5; P = 0.001) with every 5 mmHg rise in CVP for patients with CVP <9 mmHg; for CVP increments of 5 mmHg above the threshold of 9 mmHg, the risk-adjusted OR for AKI was 1.3 (95% CI 1.01-1.65; P = 0.045). This and other clinical evidence are discussed along with the underlying pathophysiological mechanisms, involving the supremacy of volume receptors in regulating the autonomic output in hypervolaemia, and the regional effect of venous congestion on the nephron. The effect of CVP on renal function was found to be modulated by ventricular function class, aetiology and acuity of venous congestion. Evidence suggests that acute increases of CVP should be actively treated to avoid a deterioration of the renal function, particularly in patients with poor ventricular fraction. Besides, the practice of treating right heart failure with fluid loading should be avoided in favour of other ways to optimize haemodynamics in this setting, because of the detrimental effects on the kidney function.

  5. Hyperthyroidism as a reversible cause of right ventricular overload and congestive heart failure

    PubMed Central

    Di Giovambattista, Raniero

    2008-01-01

    We describe a case of severe congestive heart failure and right ventricular overload associated with overt hyperthyroidism, completely reversed with antithyroid therapy in a few week. It represents a very unusual presentation of overt hyperthyroidism because of the severity of right heart failure. The impressive right ventricular volume overload made mandatory to perform transesophageal echo and angio-TC examination to exclude the coexistence of ASD or anomalous pulmonary venous return. Only a few cases of reversible right heart failure, with or without pulmonary hypertension, have been reported worldwide. In our case the most striking feature has been the normalization of the cardiovascular findings after six weeks of tiamazole therapy. PMID:18549503

  6. Venus' nighttime horizontal plasma flow, 'magnetic congestion', and ionospheric hole production

    NASA Astrophysics Data System (ADS)

    Grebowsky, J. M.; Mayr, H. G.; Curtis, S. A.; Taylor, H. A.

    1983-04-01

    A simple rectilinear, two-dimensional MHD model is used to investigate the effects of field-aligned plasma loss and cooling on a dense plasma convecting across a weak magnetic field, in order to illumine the Venus nighttime phenomena of horizontal plasma flow, magnetic congestion and ionospheric hole production. By parameterizing field-aligned variations and explicitly solving for cross magnetic field variations, it is shown that the abrupt horizontal enhancements of the vertical magnetic field, as well as sudden decreases of the plasma density to very low values (which are characteristic of ionospheric holes), can be produced in the presence of field-aligned losses.

  7. Relationship between venous pressure and tissue volume during venous congestion plethysmography in man.

    PubMed

    Christ, F; Gamble, J; Baschnegger, H; Gartside, I B

    1997-09-01

    1. Venous congestion strain-gauge plethysmography enables the non-invasive assessment of arterial blood flow, fluid filtration capacity (Kf), venous pressure (Pv) and isovolumetric venous pressure (Pvi) in man. One of the major assumptions of this technique, that cuff pressure (Pcuff) applied to the limb equals Pv at the level of the strain gauge, was tested in this study. 2. In nine healthy male volunteers (mean age, 29.3 +/- 1.2 years) the saphenous vein was cannulated with an 18-gauge catheter proximal to the medial malleolus. The subjects were supine and Pv was continuously measured during the application of small step (8-10 mmHg) increases in congestion Pcuff (up to 70 mmHg). Pcuff, changes in limb circumference and Pv were recorded by computer for off-line analysis. Since the determination of Kf is influenced by the changes in plasma oncotic pressure, venous blood samples were obtained at the start of the study, when Pcuff was raised to 30 mmHg and again to 65 mmHg and 4 min after deflation of the cuff. 3. The relationship between Pv and Pcuff was linear over the range of 10-70 mmHg (n = 9, 69 measurements, slope 0.91, r = 0.97, P < 0.001). The non-invasively measured calf Pv, based on the intercept of the relationship between the vascular compliance component (Va) and Pcuff, was 8.0 +/- 0.4 mmHg, which was not significantly different from the corrected invasively measured Pv value of 8.8 +/- 0.3 mmHg (P = 0.08). 4. Venous blood lactate and haemoglobin concentrations, as well as colloid osmotic pressure, total protein and albumin concentrations were unchanged throughout the protocol, whereas significant decreases in PO2 and blood glucose concentration were observed when Pcuff reached 65 mmHg. Assuming a constant oxygen consumption, this may suggest a reduction in tissue perfusion. 5. This study demonstrates the close correlation between Pcuff and Pv in the saphenous vein. Since the small congestion Pcuff step protocol does not cause significant increase in

  8. Fostering hope in the elderly congestive heart failure patient in critical care.

    PubMed

    Roberts, S L; Johnson, L H; Keely, B

    1999-01-01

    This article presents a patient-centered framework applied to the elderly patient with congestive heart failure (CHF). Although the elderly have been the focus of numerous articles, the needs of the elderly CHF patient in the critical care setting, especially concerning hope versus hopelessness, have been neglected. Guidelines for the clinical management of patients experiencing hopelessness are explored. The four dimensions of hopelessness discussed herein are experiential, spiritual/transcendence, irrational, and relational processes. Nursing diagnosis, interventions, goal-setting, and family support also are discussed. Helping the elderly CHF patient maintain hope when confronted with repeated hospitalizations is a challenge for the critical care nurse.

  9. Clinical education initiative in the community: caring for patients with congestive heart failure.

    PubMed

    Wheeler, Erlinda C; Plowfield, Lisa

    2004-01-01

    With greater numbers of chronically ill clients cared for in their homes rather than in acute care hospitals, nursing schools need to create and implement innovative strategies for experiences in the community setting. A telephone intervention program was initiated in the last semester of the medical-surgical clinical course to promote the health of patients with congestive heart failure and provide meaningful community experiences for senior nursing students. Students' journals from this semester-long clinical experience were analyzed and showed outcome benefits to both patients and students.

  10. Continuity of care prism process applied to the congestive heart failure population.

    PubMed

    Smoot, S M

    1998-01-01

    Emphasis in healthcare during the 1990s has been both to provide optimal wellness and function with quality in a cost-effective manner. The Continuity of Care Prism Process was developed to meet the need to guide clients along the continuum of care and to achieve continuity of care. Advanced practice nurses are the "expert" clinicians in a position to care manage clients and meet the financial and quality constraints currently being placed on healthcare agencies. In this article, the vehicle used to demonstrate the Continuity of Care Prism Process is a congestive heart failure clinical pathway.

  11. Treatment of feline asthma with ciclosporin in a cat with diabetes mellitus and congestive heart failure.

    PubMed

    Nafe, Laura A; Leach, Stacey B

    2015-12-01

    A 5-year-old domestic shorthair cat that had been previously diagnosed with diabetes mellitus was presented for episodes of coughing and respiratory distress. Diagnostic testing revealed congestive heart failure secondary to hypertrophic cardiomyopathy and concurrent asthma. All clinical signs and eosinophilic airway inflammation resolved with oral ciclosporin while the cat was concurrently receiving medications for treatment of heart failure (furosemide and enalapril). Ciclosporin should be considered for treatment of feline asthma in patients with concurrent diseases (eg, diabetes mellitus, severe heart disease) that may contraindicate use of oral glucocorticoid therapy.

  12. The aerial relay system: An energy-efficient solution to the airport congestion problem

    NASA Technical Reports Server (NTRS)

    Kyser, A. C.

    1980-01-01

    The ability to transfer airline passengers between aircraft in flight, if adequately developed and integrated into the national air transportation system, could provide significant improvements in transportation-system performance, in terms of airport congestion, fuel consumption, and passenger service. The proposed Aerial Relay System concept, which was developed as a means of exploiting inflight transfer, makes use of large 'cruise liner' aircraft which fly continuously along their routes, docking periodically with short-haul feeder aircraft for exchange of payloads. Preliminary vehicle designs for a representative system are described and the operational feasibility of the concept for the United States in the 1990's is discussed.

  13. Ethacrynic acid can be effective for refractory congestive heart failure and ascites.

    PubMed

    Alisky, Joseph M; Tuttle, Thomas F

    2003-11-01

    Ethacrynic acid is a loop diuretic little used today because of its side-effect profile and the availability of multiple alternative agents. However, in our clinical experience, ethacrynic acid can alleviate acute congestive heart failure and ascites resistant to other diuretics. Two patients aged 89 and 94 in life-threatening pulmonary edema were stabilized by ethacrynic acid after furosemide proved ineffective. A third patient, aged 83, with a pleural effusion and ascites secondary to end-stage hepatitis B and C, responded to ethacrynic acid when spironolactone and furosemide produced little urine output. Ethacrynic acid may have a unique niche as a diuretic of last resort, especially in geriatric practice.

  14. The impact of peripheral arterial disease on patients with congestive heart failure.

    PubMed

    Keswani, Amit N; White, Christopher J

    2014-04-01

    Congestive heart failure (CHF) is a prevalent disease with many comorbidities and is associated with high health care expenditures. Peripheral arterial disease (PAD) is a known comorbidity of CHF and is associated with worse morbidity and mortality. CHF and PAD share risk factors, pathophysiology, treatment strategies, and prognostic features. We review the impact of PAD on patients with CHF using several studies to support PAD's influence on outcomes in CHF. Based on the evidence and current guidelines, patients with heart failure who are smokers, and those who have known coronary artery disease and/or diabetes should be screened for PAD.

  15. Heterobilharzia americana infection and congestive heart failure in a llama (Lama glama).

    PubMed

    Corapi, W V; Eden, K B; Edwards, J F; Snowden, K F

    2015-05-01

    The schistosome Heterobilharzia americana infects several mammalian species in the southeastern United States, including horses, but infections have not been reported in camelids. This is a report of H. americana infection in a 6-year-old llama with extensive cardiac pathology and congestive heart failure. Parasite-induced granulomas were widely disseminated and included overwhelming involvement of the lungs and liver. Microscopic lesions in the heart included myofiber degeneration and necrosis, with extensive replacement fibrosis. Polymerase chain reaction amplification and sequencing confirmed the presence of H. americana in the lungs.

  16. High Performance Computing Multicast

    DTIC Science & Technology

    2012-02-01

    conditions are thus met for a myriad of critical national-asset applications that are likely to move to the cloud in the next decade. In the context of this...system conditions are thus met for a myriad of critical national-asset applications that are likely to move to the cloud in the next decade. In the...for that key. Shard mappings change as nodes join and leave the ring, and data is moved around accordingly (a form of state transfer). Coordination

  17. Effects of a family centered program on perceived social support in patients with congestive heart failure: An interventional study

    PubMed Central

    Shahriari, Mohsen; Alimohammadi, Nasrollah; Ahmadi, Maryam

    2016-01-01

    Background and Objectives: Congestive heart failure is one of the most common cardiovascular diseases that have a progressive and chronic trend and influences individuals’ and their families’ various dimensions. Social support is one of the psychosocial factors that can have a positive effect on individuals’ physical, mental and social status. Despite the existence of evidences, revealing the importance of family's support on patients’ condition, family centered supportive interventions with goal of clinical outcomes improvement have been less conducted among these patients. Therefore, the present study aimed to investigate the effect of family supportive intervention on the level of the support, received among heart failure patients. Materials and Methods: This is a two-group two-stage clinical trial, conducted on 64 patients with cardiac failure, referring to selected educational centers and meeting the inclusion criteria, who were selected through convenient sampling. They were assigned to study (n = 32) and control (n = 32) groups through random allocation. Data were collected by questioning through a two-section medical records questionnaire and were analyzed by SPSS. Results: Results of the study showed that mean scores of received support score were 13.7 (3.8) in the study and 0.8 (2.4) in the control group. Independent t-test showed a significant difference in mean changes of perceived support scores after the intervention between study and control groups (P < 0.001). Conclusions: Based on familial dimension in social support have a positive effect on patients’ perceived support. Nurses, as professional members of health care team, and with an important role in education and care of cardiac failure patients, can support, educate and guide these patients through designing appropriate care plans and educating their family members. PMID:27512698

  18. Dynamic co-expression network analysis of lncRNAs and mRNAs associated with venous congestion

    PubMed Central

    Li, Jinshun; Xu, Yuqin; Xu, Jia; Wang, Jinhua; Wu, Liying

    2016-01-01

    Venous congestion and volume overload are important in cardiorenal syndromes, in which multiple regulated factors are involved, including long non-coding RNAs (lncRNAs). To investigate the underlying role of lncRNAs in regulating the development of venous congestion, an Affymetrix microarray associated with peripheral venous congestion was annotated, then a bipartite dynamic lncRNA-mRNA co-expression network was constructed in which nodes indicated lncRNAs or mRNAs. The nodes were connected when the lncRNAs or mRNAs were dynamically co-expressed. Following functional analysis of this network, several dynamic alternative pathways were identified, including the calcium signaling pathway during venous congestion development. Additionally, certain lncRNAs (LINC00523, LINC01210 and RP11-435O5.5) were identified that may potentially dynamically regulate certain proteins, including plasma membrane calcium ATPase (PMCA) and G protein-coupled receptor (GPCR), in the calcium signaling pathway. Particularly, the dynamically regulated switch of LINC00523 from co-expression with PMCA to GPCR may be involved in damage to steady state intracellular calcium. In brief, the current study demonstrated a potential novel mechanism of lncRNA function during venous congestion. PMID:27431002

  19. The Number of Perforators Included in Reversed Flow Posterior Interosseous Artery Flap: Does It Affect the Incidence of Venous Congestion?

    PubMed Central

    Shaker, Ayman A.; Elbarbary, Amir S.; Sayed, Mohamed A.; Elghareeb, Mohamed A.

    2016-01-01

    Background: The purpose of this study is to decrease the incidence of venous congestion occurring in the reversed flow posterior interosseous artery flap used for coverage of hand defects. Methods: This may be achieved by studying the incidence of venous congestion in flaps including only 1 perforator and comparing the results with others including more than 1 perforator both in small and large sized flaps. Results: This study showed that inclusion of only 1 perforator in the flap decreased the incidence of venous congestion with complete flap loss in flaps to 5%. Also, it decreased the incidence of venous congestion with partial flap loss in flaps to 10%. Conclusions: The small sized reversed flow posterior interosseous artery flap should be less than 40 cm2 and should include only 1 perforator to decrease the incidence of venous congestion with partial and complete loss of the flap. The level of evidence for this study is the type II prospective comparative study. PMID:28293513

  20. Multifractal properties of ECG patterns of patients suffering from congestive heart failure

    NASA Astrophysics Data System (ADS)

    Dutta, Srimonti

    2010-12-01

    The multifractal properties of two-channel ECG patterns of patients suffering from severe congestive heart failure (New York Heart Association (NYHA) classes III-IV) are studied and are compared with those for normal healthy people using the multifractal detrended fluctuation analysis methodology. Ivanov et al (1999 Nature 399 461) have studied the multifractality of human heart rate dynamics using the wavelet transformation modulus maxima (WTMM) methodology. But it has been observed by several scientists that multifractal detrended fluctuation analysis (MFDFA) works better than the WTMM method in the detection of monofractal and multifractal characteristics of the data. Galaska et al (2008 Ann. Noninvasive Electrocardiol. 13 155) have observed that MFDFA is more sensitive compared to the WTMM method in the differentiation between multifractal properties of the heart rate in healthy subjects and patients with left ventricular systolic dysfunction. In the present work the variation of two parameters of the multifractal spectrum—its width W (related to the degree of multifractality) and the value of the Hölder exponent α0—for the healthy and congestive heart failure patients is studied. α0 is a measure of the degree of correlation. The degree of multifractality varies appreciably (85-90% C.L.) for the normal and the CHF sets for channel I. For channel II no significant change in the values is observed. The degree of correlation is found to be comparatively high for the normal healthy people compared to those suffering from CHF.

  1. [Renal dysfunction in heart failure and hypervolumenia : Importance of congestion and backward failure].

    PubMed

    Druml, W

    2014-05-01

    Traditionally, renal dysfunction in congestive heart failure (cardiorenal syndrome type 1) has been attributed to reduced cardiac output and low mean arterial perfusion pressure, which elicit a series of neurohumoral activations resulting in increased renal vascular resistance and decreased renal function.During the last decade, several studies have shown that the extent of renal dysfunction is not so closely associated with indices of forward failure-such as the cardiac index or mean arterial pressure-but rather with indicators of congestion, such as left ventricular enddiasystolic pressure or central venous pressure (CVP), which are indicators of backward failure. The impact of backward failure on renal function is not confined to an elevation of CVP, the renal drainage pressure, but includes a broad spectrum of mechanisms. Involved are the organ systems right heart, lung, the liver, the proinflammatory signals originating from the intestines, but also renal interstitial edema (renal compartment syndrome) and the intraabdominal pressure.The therapeutic measures must focus on the modulation of the preload adapted to the specific situation of an individual patient. This includes diuretics aiming at different segments of the tubulus system including antagonists of aldosteron and ADH, extracorporeal fluid elimination by ultrafiltration or peritoneal dialysis.

  2. Evaluation of the time course of vascular responses to venous congestion in the human lower limb.

    PubMed

    Oldfield, Mark A; Brown, Margaret D

    2006-01-01

    This study examined the time course of changes in blood flow to the lower leg in response to venous distension--the veni-arteriolar vasoconstrictor response--in 31 healthy males. During a 5-min period of venous distension (thigh cuff pressure 50 mm Hg), calf blood flow (venous occlusion plethysmography) decreased more rapidly (within 30 s) compared to skin perfusion (after 2 min, Laser Doppler flowmetry), consistent with disparate filling times of superficial and deeper veins and a greater increase in deep vein volume. On completion of venous filling, vascular resistance in the skin was unchanged from baseline, implying that the reduction in perfusion was solely the result of reduced perfusion pressure. For the whole calf, vascular resistance was unchanged after 1 min but decreased thereafter by 35-45% from baseline, indicating adjustment of pre- or post-capillary resistances to maintain flow. Repeated plethysmographic flow measurements assisted the decrease in resistance, most likely by intermittent compression of the thigh cuff acting to displace blood volume centrally and alleviate congestion. These findings do not support an active veni-arteriolar vasoconstrictor mechanism in response to venous distension alone in the lower leg, and provide evidence of dynamic flow adjustments that should be acknowledged during procedures that involve prolonged periods of venous congestion.

  3. Metabolic cardiology: an integrative strategy in the treatment of congestive heart failure.

    PubMed

    Sinatra, Stephen T

    2009-01-01

    Congestive heart failure (CHF) and dilated cardiomyopathy are life-threatening conditions in which the heart muscle is so weak that effective pulsatile action is compromised. Pulmonary vascular congestion and swelling in the lower extremities as well as in the liver and lining of the gastrointestinal tract frequently cause overwhelming symptoms and disability. Millions of Americans suffer from CHF, and more than 500,000 cases are diagnosed annually. Cardiovascular diseases such as hypertension with left ventricular hypertrophy, valvular heart disease, coronary artery disease, myocarditis, and various cardiomyopathies can lead to the progressive onset of CHF. The purpose of this communication article is to introduce metabolic cardiology as a vital therapeutic strategy utilizing nutritional biochemical interventions that preserve and promote adenosine triphosphate (ATP) production. Treatment options that incorporate metabolic interventions targeted to preserve energy substrates (D-ribose) or accelerate ATP turnover (L-carnitine and coenzyme Q10) are indicated for at-risk populations or patients at any stage of CHF. The integration of these metabolic supports provides the missing link in CHF treatment that has been eluding physicians for decades.

  4. [Nursing diagnoses and interventions for patients with congestive heart failure using the ICNP ®].

    PubMed

    de Araújo, Angela Amorim; da Nóbrega, Maria Miriam Lima; Garcia, Telma Ribeiro

    2013-04-01

    The aim of this descriptive exploratory study was to construct nursing diagnosis and intervention statements for patients with Congestive Heart Failure. To accomplish this aim, 53 terms were identified in the focus axis of the International Classification for Nursing Practice (ICNP®), which guided the construction of these statements using the guidelines of the International Council of Nurses and ISO 18. 104. A total of 92 nursing diagnosis statements were constructed, which resulted in 66 statements after standardization. The standardized statements were separated according to the following pathophysiological models: 13 related to tachycardia, 20 related to dyspnea, 19 related to edema, and 14 related to congestion. A total of 234 interventions were constructed for these statements using the terms from the 7-Axis Model of the ICNP®, the literature in the area and the clinical experience of the authors. The nursing diagnosis and intervention statements designed are expected to facilitate the evaluation of CHF patients and assist in the construction of a terminological subset for the ICNP®.

  5. Diagnosis and treatment of congestive heart failure secondary to dilated cardiomyopathy in a hedgehog.

    PubMed

    Delk, K W; Eshar, D; Garcia, E; Harkin, K

    2014-03-01

    A one-year-old African pygmy hedgehog (Atelerix albiventris) was evaluated for severe respiratory distress. Physical examination findings included marked dyspnoea, cyanosis and tachypnoea. Radiographic findings included an enlarged heart and pulmonary oedema, and dilated cardiomyopathy was confirmed via echocardiogram. The patient was treated for congestive heart failure because of dilated cardiomyopathy with furosemide, enalapril, pimobendan and l-carnitine. Within 24 hours of treatment, the pulmonary oedema and cyanosis had resolved. Following discharge, clinical improvement was noted by the owner and echocardiogram confirmed improved fractional shortening. Cardiomyopathy has been reported at post-mortem examination in hedgehogs, but there are no reports of ante-mortem diagnosis and treatment. Performing baseline cardiac assessment in hedgehogs is recommended, and treatment with l-carnitine and pimobendan may improve outcome, as carnitine deficiency is a possible cause of cardiomyopathy in hedgehogs. Successful emergency treatment of congestive heart failure in the hedgehog of this report may be effective for other hedgehogs presented with similar clinical signs.

  6. Congestion detection of pedestrians using the velocity entropy: A case study of Love Parade 2010 disaster

    NASA Astrophysics Data System (ADS)

    Huang, Lida; Chen, Tao; Wang, Yan; Yuan, Hongyong

    2015-12-01

    Gatherings of large human crowds often result in crowd disasters such as the Love Parade Disaster in Duisburg, Germany on July 24, 2010. To avoid these tragedies, video surveillance and early warning are becoming more and more significant. In this paper, the velocity entropy is first defined as the criterion for congestion detection, which represents the motion magnitude distribution and the motion direction distribution simultaneously. Then the detection method is verified by the simulation data based on AnyLogic software. To test the generalization performance of this method, video recordings of a real-world case, the Love Parade disaster, are also used in the experiments. The velocity histograms of the foreground object in the videos are extracted by the Gaussian Mixture Model (GMM) and optical flow computation. With a sequential change-point detection algorithm, the velocity entropy can be applied to detect congestions of the Love Parade festival. It turned out that without recognizing and tracking individual pedestrian, our method can detect abnormal crowd behaviors in real-time.

  7. A Review of Transport Protocols as Candidates for Use in a Tactical Environment

    DTIC Science & Technology

    2005-12-01

    example, if the receiver must maintain radio silence) for an extended period of time. The multicast groups DSTO-TR-1808 14 are globally handled...a Global Internet”, IEEE Journal on Selected Areas in Communications, Volume 13, Number 8, October 1995. DSTO-TR-1808 29 [CCSDS99] “Space...TCP Westwood: congestion window control using bandwidth estimation”, Global Telecommunications Conference 2001, GLOBECOM ’01, IEEE Volume 3, 25-29

  8. [Effects of hot water bath or sauna on patients with congestive heart failure: acute hemodynamic improvement by thermal vasodilation].

    PubMed

    Tei, C; Horikiri, Y; Park, J C; Jeong, J W; Chang, K S; Tanaka, N; Toyama, Y

    1994-01-01

    The acute hemodynamic effects of thermal vasodilation caused by exposure to hot water bath or sauna in chronic congestive heart failure were investigated in 32 patients (mean age 57 +/- 15 years old) with dilated cardiomyopathy (25 idiopathic and 7 ischemic). The clinical symptoms were New York Heart Association Class II in 2 patients, III in 17 and IV in 13, and the mean ejection fraction was 25 +/- 9% (9-44%). Exposure to hot water bath was for 10 minutes at 41 degrees C in a semi-sitting position, and to sauna for 15 minutes at 60 degrees C in a supine position using a special far infrared ray sauna chamber. Blood pressure, electrocardiogram, two-dimensional and Doppler echocardiograms, expiration gas, and intracardiac pressure tracings were recorded before (control), during, and 30 minutes after hot water bath or sauna. 1. The increase in oxygen consumption was only 0.3 Mets during hot water bath or sauna, and returned to the control level 30 minutes later. 2. The deep temperature in the main pulmonary artery increased by 1.0-1.2 degrees C on average at the end of hot water bath or sauna. 3. Heart rate increased significantly (p < 0.01) by 20-25/min during bathing and still increased 30 min later. 4. Systolic blood pressure did not change significantly during and after hot water bath or sauna, while, diastolic blood pressure decreased significantly during (p < 0.05) and after sauna (p < 0.01), and after hot water bath (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Oral administration of eicosapentaenoic acid or docosahexaenoic acid modifies cardiac function and ameliorates congestive heart failure in male rats.

    PubMed

    Yamanushi, Tomoko T; Kabuto, Hideaki; Hirakawa, Eiichiro; Janjua, Najma; Takayama, Fusako; Mankura, Mitsumasa

    2014-04-01

    This study assessed the effects of eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on normal cardiac function (part 1) and congestive heart failure (CHF) (part 2) through electrocardiogram analysis and determination of EPA, DHA, and arachidonic acid (AA) concentrations in rat hearts. In part 2, pathologic assessments were also performed. For part 1 of this study, 4-wk-old male rats were divided into a control group and 2 experimental groups. The rats daily were orally administered (1 g/kg body weight) saline, EPA-ethyl ester (EPA-Et; E group), or DHA-ethyl ester (DHA-Et; D group), respectively, for 28 d. ECGs revealed that QT intervals were significantly shorter for groups E and D compared with the control group (P ≤ 0.05). Relative to the control group, the concentration of EPA was higher in the E group and concentrations of EPA and DHA were higher in the D group, although AA concentrations were lower (P ≤ 0.05). In part 2, CHF was produced by subcutaneous injection of monocrotaline into 5-wk-old rats. At 3 d before monocrotaline injection, rats were administered either saline, EPA-Et, or DHA-Et as mentioned above and then killed at 21 d. The study groups were as follows: normal + saline (control), CHF + saline (H group), CHF + EPA-Et (HE group), and CHF + DHA-Et (HD group). QT intervals were significantly shorter (P ≤ 0.05) in the control and HD groups compared with the H and HE groups. Relative to the H group, concentrations of EPA were higher in the HE group and those of DHA were higher in the control and HD groups (P ≤ 0.05). There was less mononuclear cell infiltration in the myocytes of the HD group than in the H group (P = 0.06). The right ventricles in the H, HE, and HD groups showed significantly increased weights (P ≤ 0.05) compared with controls. The administration of EPA-Et or DHA-Et may affect cardiac function by modification of heart fatty acid composition, and the administration of DHA-Et may ameliorate CHF.

  10. The kidney in congestive heart failure: 'are natriuresis, sodium, and diuretics really the good, the bad and the ugly?'.

    PubMed

    Verbrugge, Frederik H; Dupont, Matthias; Steels, Paul; Grieten, Lars; Swennen, Quirine; Tang, W H Wilson; Mullens, Wilfried

    2014-02-01

    This review discusses renal sodium handling in heart failure. Increased sodium avidity and tendency to extracellular volume overload, i.e. congestion, are hallmark features of the heart failure syndrome. Particularly in the case of concomitant renal dysfunction, the kidneys often fail to elicit potent natriuresis. Yet, assessment of renal function is generally performed by measuring serum creatinine, which has inherent limitations as a biomarker for the glomerular filtration rate (GFR). Moreover, glomerular filtration only represents part of the nephron's function. Alterations in the fractional reabsorptive rate of sodium are at least equally important in emerging therapy-refractory congestion. Indeed, renal blood flow decreases before the GFR is affected in congestive heart failure. The resulting increased filtration fraction changes Starling forces in peritubular capillaries, which drive sodium reabsorption in the proximal tubules. Congestion further stimulates this process by augmenting renal lymph flow. Consequently, fractional sodium reabsorption in the proximal tubules is significantly increased, limiting sodium delivery to the distal nephron. Orthosympathetic activation probably plays a pivotal role in those deranged intrarenal haemodynamics, which ultimately enhance diuretic resistance, stimulate neurohumoral activation with aldosterone breakthrough, and compromise the counter-regulatory function of natriuretic peptides. Recent evidence even suggests that intrinsic renal derangements might impair natriuresis early on, before clinical congestion or neurohumoral activation are evident. This represents a paradigm shift in heart failure pathophysiology, as it suggests that renal dysfunction-although not by conventional GFR measurements-is driving disease progression. In this respect, a better understanding of renal sodium handling in congestive heart failure is crucial to achieve more tailored decongestive therapy, while preserving renal function.

  11. Changes in derived measures from six-minute walk distance following home-based exercise training in congestive heart failure: A preliminary report.

    PubMed

    Babu, Abraham Samuel; Desai, Charmie V; Maiya, Arun G; Guddattu, Vasudeva; Padmakumar, Ramachandran

    2016-01-01

    The response of derived parameters from six-minute walk distance (6MWD), like 6MW work (6MWW), to exercise training and its correlation with quality of life (QoL) in congestive heart failure (CHF) is not known. A secondary analysis from a randomized controlled trial on 30 patients (23 males; mean age 57.7±10.4 years; mean ejection fraction 31±10%) with CHF in NYHA class I-IV who completed an eight-week home-based exercise training program found a significant improvement in 6MWW (p<0.05), with similar correlations between 6MWD and 6MWW with QoL. 6MWW does not appear to provide additional benefit to 6MWD in cardiac rehabilitation for CHF.

  12. Use of intranasal corticosteroids in the management of congestion and sleep disturbance in pediatric patients with allergic rhinitis.

    PubMed

    Lanier, Bob Q

    2008-06-01

    Allergic rhinitis affects a large number of children and exerts a considerable socioeconomic impact. It is underdiagnosed and inadequately treated, which predisposes children to potentially serious comorbidities. Allergic rhinitis symptoms may create nighttime breathing problems and sleep disturbances and have a negative effect on a child's ability to learn in the classroom. Although antihistamines have shown efficacy in relieving many symptoms, they have little effect on nasal congestion. This article summarizes the advantages of intranasal corticosteroids, including their effectiveness against congestion and excellent safety profile. Intranasal corticosteroids with minimal systemic bioavailability provide topical drug delivery that minimizes the potential for systemic side-effects.

  13. Sleep disturbances in caregivers of patients with end-stage congestive heart failure: Part II--assess and intervene.

    PubMed

    Rausch, Sarah M; Baker, Kathy; Boonmee, Junyanee

    2007-01-01

    Sleep disturbances in caregivers of patients with congestive heart failure is common. The consequences of sleep disturbances are dire and have potential to seriously impact caregiver health and patient outcomes. Therefore, it is imperative that the health care team, especially nurses, assess and intervene. Basic assessment of caregiver sleep disturbance can be quick and simple and can be performed while assessing the congestive heart failure patient's health. If a more complex sleep disorder is suspected, other assessments can be conducted if time and money permit. The benefits to properly assessing sleep disturbance and subsequent treatment far outweigh the minimal time spent by the health care team or caregiver.

  14. Measuring outcomes in allergic rhinitis: psychometric characteristics of a Spanish version of the congestion quantifier seven-item test (CQ7)

    PubMed Central

    2011-01-01

    Background No control tools for nasal congestion (NC) are currently available in Spanish. This study aimed to adapt and validate the Congestion Quantifier Seven Item Test (CQ7) for Spain. Methods CQ7 was adapted from English following international guidelines. The instrument was validated in an observational, prospective study in allergic rhinitis patients with NC (N = 166) and a control group without NC (N = 35). Participants completed the CQ7, MOS sleep questionnaire, and a measure of psychological well-being (PGWBI). Clinical data included NC severity rating, acoustic rhinometry, and total symptom score (TSS). Internal consistency was assessed using Cronbach's alpha and test-retest reliability using the intraclass correlation coefficient (ICC). Construct validity was tested by examining correlations with other outcome measures and ability to discriminate between groups classified by NC severity. Sensitivity and specificity were assessed using Area under the Receiver Operating Curve (AUC) and responsiveness over time using effect sizes (ES). Results Cronbach's alpha for the CQ7 was 0.92, and the ICC was 0.81, indicating good reliability. CQ7 correlated most strongly with the TSS (r = 0.60, p < 0.01), the PGWBI general health dimension (r = 0.56, p < 0.01), and the MOS Sleep scale 'sleep short of breath' dimension (r = 0.49, p < 0.01). Correlations with acoustic rhinometry were generally low. The instrument discriminated well between NC severity groups (ES 0.33-2.07) and AUC was 0.93, indicating excellent sensitivity and specificity. The measure was responsive to change (ES = 1.1) in patients reporting improvement in NC. Conclusions The Spanish version of the CQ7 is appropriate for detecting, measuring, and monitoring NC in allergic rhinitis patients. PMID:21392375

  15. Left ventricular filling after long-term angiotensin converting enzyme inhibition in congestive heart failure.

    PubMed

    Baur, L H; Schipperheyn, J J; Cats, V M; van der Wall, E E; Baan, J; van Dijk, A D; Bruschke, A V

    1992-11-01

    As a rule, left ventricular relaxation is impaired in patients with coronary artery disease and congestive heart failure. In addition, the passive elastic properties in early and late diastole change when the ventricle dilates. Diastolic properties of the left ventricle were studied in 11 patients with congestive heart failure class II-IV (NYHA) before and 3 months after 10-20 mg enalapril was added to their regimen of salt restriction, a diuretic and occasionally digitalis. Haemodynamic studies were performed using radionuclide angiography and simultaneous pressure-volume measurements. Systemic vascular resistance decreased from 1479 to 1182 dynes.s.-1 cm-5 (P < 0.05) and left ventricular end-diastolic pressure from 19.2 to 15.9 mmHg (P < 0.05). Left ventricular end-diastolic volume index decreased from 130 +/- 22 to 81 +/- 22 ml (P < 0.01). Indices of early diastolic relaxation, such as peak filling rate (1.43 +/- 0.46 to 1.49 +/- 0.84 EDV/s), time to peak filling rate (460 +/- 70 to 490 +/- 70 ms), peak negative dP/dt (-903 +/- 190 to -891 +/- 190 mmHg/s) and tau, the time constant of isovolumic pressure decay (58.7 +/- 14.4 to 48.4 +/- 15.2 ms) did not change significantly. In nine patients pressure-volume loops shifted to the left in all patients but one due to reduction in end-systolic and end-diastolic volume. The steepness of the diastolic part of the pressure-volume relationship increased, indicating an increase in chamber stiffness. The stiffness constant increased about 25% towards a more normal value. The alteration in stiffness seemed to be mainly due to the change of the geometry of the ventricle and not to a major change in the visco-elastic properties of the ventricular wall. In conclusion, regression of remodelling induced by enalapril does not change diastolic function parameters in patients with chronic congestive heart failure beyond the changes caused by regression of ventricular dilation.

  16. Asymptomatic Left Bundle Branch Block Predicts New-Onset Congestive Heart Failure and Death From Cardiovascular Diseases

    PubMed Central

    Azadani, Peyman N.; Soleimanirahbar, Ata; Marcus, Gregory M.; Haight, Thaddeus J.; Hollenberg, Milton; Olgin, Jeffrey E.; Lee, Byron K.

    2012-01-01

    Background Left bundle branch block (LBBB) has been proposed as a risk factor for cardiovascular morbidity and mortality. We sought to characterize the strength of these associations in a population without preexisting clinical heart disease. Methods The association between LBBB and new-onset congestive heart failure (CHF) or death from cardiovascular diseases was examined in 1,688 participants enrolled in the SPPARCS study who were free of known CHF or previous myocardial infarction. SPPARCS is a community-based cohort study in residents of Sonoma, California that are > 55 years. Medical history and 12-lead ECGs were obtained every 2 years for up to 6 years of follow-up. LBBB at enrollment or year 2 was considered “baseline” and assessed as a predictor of CHF and cardiovascular death ascertained at years 4 and 6. Results The prevalence of LBBB at baseline was 2.5% (n = 42). During 6 years of follow-up, 70 (4.8%) people developed new CHF. Incidence of CHF was higher in patients with LBBB than in participants without LBBB. This association persisted after controlling for potential confounders (odds ratio (OR): 2.85; 95% confidence interval (CI): 1.01 - 8.02; P = 0.047). A higher mortality from cardiovascular diseases was also found in participants with LBBB after adjusting for potential confounders (OR: 2.35, 95%CI: 1.02 - 5.41; P = 0.044). Conclusions LBBB in the absence of a clinically detectable heart disease is associated with new-onset CHF and death from cardiovascular diseases. Further study is warranted to determine if additional diagnostic testing or earlier treatment in patients with asymptomatic LBBB can decrease cardiovascular morbidity or mortality.

  17. Weight Management Belief is the Leading Influential Factor of Weight Monitoring Compliance in Congestive Heart Failure Patients

    PubMed Central

    Lu, Min-Xia; Zhang, Yan-Yun; Jiang, Jun-Fang; Ju, Yang; Wu, Qing; Zhao, Xin; Wang, Xiao-Hua

    2016-01-01

    Background Daily weight monitoring is frequently recommended as a part of heart failure self-management to prevent exacerbations. This study is to identify factors that influence weight monitoring compliance of congestive heart failure patients at baseline and after a 1-year weight management (WM) program. Methods This was a secondary analysis of an investigative study and a randomized controlled study. A general information questionnaire assessed patient demographics and clinical variables such as medicine use and diagnoses, and the weight management scale evaluated their WM abilities. Good and poor compliance based on abnormal weight gain from the European Society of Cardiology (> 2 kg in 3 days) were compared, and hierarchical multiple logistic regression analysis was used to identify factors influencing weight monitoring compliance. Results A total of 316 patients were enrolled at baseline, and 66 patients were enrolled after the 1-year WM program. Of them, 12.66% and 60.61% had good weight monitoring compliance at baseline and after 1 year of WM, respectively. A high WM-related belief score indicated good weight monitoring compliance at both time points [odds ratio (OR), 1.043, 95% confidence interval (CI), 1.023-1.063, p < 0.001; and OR, 2.054, 95% CI, 1.209-3.487, p < 0.001, respectively). Patients with a high WM-related practice score had good weight monitoring compliance at baseline (OR, 1.046, 95% CI, 1.027-1.065, p < 0.001), and patients who had not monitored abnormal weight had poor weight monitoring compliance after the 1-year WM program (OR, 0.244, 95% CI, 0.006-0.991, p = 0.049). Conclusions Data from this study suggested that belief related to WM plays an important role in weight monitoring compliance. PMID:27899858

  18. New Results in Magnitude and Sign Correlations in Heartbeat Fluctuations for Healthy Persons and Congestive Heart Failure (CHF) Patients

    NASA Astrophysics Data System (ADS)

    Diosdado, A. Muñoz; Cruz, H. Reyes; Hernández, D. Bueno; Coyt, G. Gálvez; González, J. Arellanes

    2008-08-01

    Heartbeat fluctuations exhibit temporal structure with fractal and nonlinear features that reflect changes in the neuroautonomic control. In this work we have used the detrended fluctuation analysis (DFA) to analyze heartbeat (RR) intervals of 54 healthy subjects and 40 patients with congestive heart failure during 24 hours; we separate time series for sleep and wake phases. We observe long-range correlations in time series of healthy persons and CHF patients. However, the correlations for CHF patients are weaker than the correlations for healthy persons; this fact has been reported by Ashkenazy et al. [1] but with a smaller group of subjects. In time series of CHF patients there is a crossover, it means that the correlations for high and low frequencies are different, but in time series of healthy persons there are not crossovers even if they are sleeping. These crossovers are more pronounced for CHF patients in the sleep phase. We decompose the heartbeat interval time series into magnitude and sign series, we know that these kinds of signals can exhibit different time organization for the magnitude and sign and the magnitude series relates to nonlinear properties of the original time series, while the sign series relates to the linear properties. Magnitude series are long-range correlated, while the sign series are anticorrelated. Newly, the correlations for healthy persons are different that the correlations for CHF patients both for magnitude and sign time series. In the paper of Ashkenazy et al. they proposed the empirical relation: αsign≈1/2(αoriginal+αmagnitude) for the short-range regime (high frequencies), however, we have found a different relation that in our calculations is valid for short and long-range regime: αsign≈1/4(αoriginal+αmagnitude).

  19. Usefulness of verapamil for congestive heart failure associated with abnormal left ventricular diastolic filling and normal left ventricular systolic performance

    SciTech Connect

    Setaro, J.F.; Zaret, B.L.; Schulman, D.S.; Black, H.R.; Soufer, R. )

    1990-10-15

    Normal left ventricular systolic performance with impaired left ventricular diastolic filling may be present in a substantial number of patients with congestive heart failure (CHF). To evaluate the effect of oral verapamil in this subset, 20 men (mean age 68 +/- 5 years) with CHF, intact left ventricular function (ejection fraction greater than 45%) and abnormal diastolic filling (peak filling rate less than 2.5 end-diastolic volumes per second (edv/s)) were studied in a placebo-controlled, double-blind 5-week crossover trial. All patients underwent echocardiography to rule out significant valvular disease, and thallium-201 stress scintigraphy to exclude major active ischemia. Compared to baseline values, verapamil significantly improved exercise capacity by 33% (13.9 +/- 4.3 vs 10.7 +/- 3.4 minutes at baseline) and peak filling rate by 30% (2.29 +/- 0.54 vs 1.85 +/- 0.45 edv/s at baseline) (all p less than 0.05). Placebo values were 12.3 +/- 4.0 minutes and 2.16 +/- 0.48 edv/s, respectively (difference not significant for both). Improvement from baseline in an objective clinico-radiographic heart failure score (scale 0 to 13) was significantly greater with verapamil compared to placebo (median improvement in score: 3 vs 1, p less than 0.01). Mean ejection fraction and systolic blood pressure were unchanged from baseline; diastolic blood pressure and heart rate decreased to a small degree. Verapamil may have therapeutic efficacy in patients with CHF, preserved systolic function and impaired diastolic filling.

  20. Pioglitazone-induced congestive heart failure and pulmonary edema in a patient with preserved ejection fraction

    PubMed Central

    Jearath, Vaneet; Vashisht, Rajan; Rustagi, Vipul; Raina, Sujeet; Sharma, Rajesh

    2016-01-01

    Pioglitazone-induced heart failure is known in patients with underlying heart disease, but is not well documented in patients with normal left ventricular function. Pioglitazone has been very popular as it is an insulin sensitizer and insulin resistance is prevalent among Indians. Fluid retention exacerbates pre-existing heart failure or precipitates heart failure in a patient with underlying left ventricular dysfunction. However, pathogenesis of heart failure in a patient with normal left ventricular function is not known. Probably it is due to dose-related effect on pulmonary endothelial permeability, rather than alterations in left ventricular mass or ejection fraction. We report a patient who developed congestive heart failure and pulmonary edema with normal left ventricular function within 1 year of starting pioglitazone therapy. We have to be careful in monitoring all possible side effects during followup when patients are on pioglitazone therapy. PMID:27127397