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Sample records for multicast congestion control

  1. Fixed-rate layered multicast congestion control

    NASA Astrophysics Data System (ADS)

    Bing, Zhang; Bing, Yuan; Zengji, Liu

    2006-10-01

    A new fixed-rate layered multicast congestion control algorithm called FLMCC is proposed. The sender of a multicast session transmits data packets at a fixed rate on each layer, while receivers each obtain different throughput by cumulatively subscribing to deferent number of layers based on their expected rates. In order to provide TCP-friendliness and estimate the expected rate accurately, a window-based mechanism implemented at receivers is presented. To achieve this, each receiver maintains a congestion window, adjusts it based on the GAIMD algorithm, and from the congestion window an expected rate is calculated. To measure RTT, a new method is presented which combines an accurate measurement with a rough estimation. A feedback suppression based on a random timer mechanism is given to avoid feedback implosion in the accurate measurement. The protocol is simple in its implementation. Simulations indicate that FLMCC shows good TCP-friendliness, responsiveness as well as intra-protocol fairness, and provides high link utilization.

  2. 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.

  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. 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.

  6. 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.

  7. 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)

  8. Congestion control and avoidance for ATM networks

    NASA Astrophysics Data System (ADS)

    Wu, Chih-Ming

    1997-10-01

    The flow of papers proposing new schemes to cope with congestion in networks continues unabated. In particular as the deployment of ATM networks advances effective congestion control is required to ensure that these networks can effectively provide the wide range of services that they promise. This paper attempts to evaluate whether recently proposed algorithms are likely to be useful in practice using performance simulation and modeling methods. However the performance is very sensitive to the flow control parameters and identifying an appropriate set of parameters is difficult since it depends heavily on the traffic conditions. The aim of this paper described is to broaden the context within which ATM performance is considered, and outline ongoing work in performance evaluation of ATM networks. This paper presents the complete picture for evaluating the properties of congestion control mechanisms including fairness, overhead, data loss and network utilization are described. It is particularly aimed at estimating the effects of recent congestion control schemes for ATM networks.

  9. Avoiding congestion through dynamic load control

    NASA Astrophysics Data System (ADS)

    Hnatyshin, Vasil; Sethi, Adarshpal S.

    2001-07-01

    The current best effort approach to quality of service in the Internet can no longer satisfy a diverse variety of customer service requirements, and that is why there is a need for alternative strategies. In order to solve this problem a number of service differentiation models have been proposed. Unfortunately, these schemes often fail to provide proper service differentiation during periods of congestion. To deal with the issue of congestion, we introduce a new load control mechanism that eliminates congestion based on the feedback from the network core by dynamically adjusting traffic load at the network boundary. We introduce four methods for calculating load distribution among the ingress routers and among different flows in each ingress router, and we evaluate these proposed methods through simulation.

  10. Performance analysis of reactive congestion control for ATM networks

    NASA Astrophysics Data System (ADS)

    Kawahara, Kenji; Oie, Yuji; Murata, Masayuki; Miyahara, Hideo

    1995-05-01

    In ATM networks, preventive congestion control is widely recognized for efficiently avoiding congestion, and it is implemented by a conjunction of connection admission control and usage parameter control. However, congestion may still occur because of unpredictable statistical fluctuation of traffic sources even when preventive control is performed in the network. In this paper, we study another kind of congestion control, i.e., reactive congestion control, in which each source changes its cell emitting rate adaptively to the traffic load at the switching node (or at the multiplexer). Our intention is that, by incorporating such a congestion control method in ATM networks, more efficient congestion control is established. We develop an analytical model, and carry out an approximate analysis of reactive congestion control algorithm. Numerical results show that the reactive congestion control algorithms are very effective in avoiding congestion and in achieving the statistical gain. Furthermore, the binary congestion control algorithm with pushout mechanism is shown to provide the best performance among the reactive congestion control algorithms treated here.

  11. 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

  12. 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.

  13. Performance Evaluation of Reliable Multicast Protocol for Checkout and Launch Control Systems

    NASA Technical Reports Server (NTRS)

    Shu, Wei Wennie; Porter, John

    2000-01-01

    The overall objective of this project is to study reliability and performance of Real Time Critical Network (RTCN) for checkout and launch control systems (CLCS). The major tasks include reliability and performance evaluation of Reliable Multicast (RM) package and fault tolerance analysis and design of dual redundant network architecture.

  14. Distributed control of multicast Internet communications with variable QoS constraints

    NASA Astrophysics Data System (ADS)

    Houatra, Drissa

    2001-07-01

    This paper describes a framework for the design of next generations of multicast services. The framework is based on active and programmable networks, distributed objects and distributed control algorithms with quality-of-service (QoS) constraints. Many of the Internet applications require variable (dynamic) QoS guarantees from networks. This is the case of distributed virtual environments that support the execution of simulation applications, or audio-video communication applications over the Internet. With the development of active and programmable networks, distributed object platforms and system technologies, it becomes feasible to provide multicast services that can be controlled to adapt the allocation of network resources to QoS variations. Multicast services based on the framework described in this paper can be used by application software components to manage network resources, to bring modifications to computations associated to network nodes, and to easily implement distributed control algorithms and services that can take into account variable QoS requirements expressed by applications. The paper focuses on the principles that govern the design and implementation of multicast protocols based on this framework, and the study of some of their major benefits. This work is partially supported by the European Commission - IST research program, under agreement IST-1999-10561: project FAIN.

  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. 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.

  17. 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.

  18. 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.

  19. Autonomous Congestion Control in Delay-Tolerant Networks

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.; Jennings, Esther H.

    2005-01-01

    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).

  20. Event-driven approach of layered multicast to network adaptation in RED-based IP networks

    NASA Astrophysics Data System (ADS)

    Nahm, Kitae; Li, Qing; Kuo, C.-C. J.

    2003-11-01

    In this work, we investigate the congestion control problem for layered video multicast in IP networks of active queue management (AQM) using a simple random early detection (RED) queue model. AQM support from networks improves the visual quality of video streaming but makes network adaptation more di+/-cult for existing layered video multicast proticols that use the event-driven timer-based approach. We perform a simplified analysis on the response of the RED algorithm to burst traffic. The analysis shows that the primary problem lies in the weak correlation between the network feedback and the actual network congestion status when the RED queue is driven by burst traffic. Finally, a design guideline of the layered multicast protocol is proposed to overcome this problem.

  1. Evaluation of TCP congestion control algorithms.

    SciTech Connect

    Long, Robert Michael

    2003-12-01

    Sandia, Los Alamos, and Lawrence Livermore National Laboratories currently deploy high speed, Wide Area Network links to permit remote access to their Supercomputer systems. The current TCP congestion algorithm does not take full advantage of high delay, large bandwidth environments. This report involves evaluating alternative TCP congestion algorithms and comparing them with the currently used congestion algorithm. The goal was to find if an alternative algorithm could provide higher throughput with minimal impact on existing network traffic. The alternative congestion algorithms used were Scalable TCP and High-Speed TCP. Network lab experiments were run to record the performance of each algorithm under different network configurations. The network configurations used were back-to-back with no delay, back-to-back with a 30ms delay, and two-to-one with a 30ms delay. The performance of each algorithm was then compared to the existing TCP congestion algorithm to determine if an acceptable alternative had been found. Comparisons were made based on throughput, stability, and fairness.

  2. 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.

  3. 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.

  4. 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.

  5. Cooperative multiagent congestion control for high-speed networks.

    PubMed

    Hwang, Kao-Shing; Tan, Shun-Wen; Hsiao, Ming-Chang; Wu, Cheng-Shong

    2005-04-01

    An adaptive multiagent reinforcement learning method for solving congestion control problems on dynamic high-speed networks is presented. Traditional reactive congestion control selects a source rate in terms of the queue length restricted to a predefined threshold. However, the determination of congestion threshold and sending rate is difficult and inaccurate due to the propagation delay and the dynamic nature of the networks. A simple and robust cooperative multiagent congestion controller (CMCC), which consists of two subsystems: a long-term policy evaluator, expectation-return predictor and a short-term rate selector composed of action-value evaluator and stochastic action selector elements has been proposed to solve the problem. After receiving cooperative reinforcement signals generated by a cooperative fuzzy reward evaluator using game theory, CMCC takes the best action to regulate source flow with the features of high throughput and low packet loss rate. By means of learning procedures, CMCC can learn to take correct actions adaptively under time-varying environments. Simulation results showed that the proposed approach can promote the system utilization and decrease packet losses simultaneously.

  6. Flow and congestion control for Internet media streaming applications

    NASA Astrophysics Data System (ADS)

    Cen, Shanwei; Walpole, Jonathan; Pu, Calton

    1997-12-01

    The emergence of streaming multimedia players provides users with low latency audio and video content over the Internet. Providing high-quality, best-effort, real-time multimedia content requires adaptive delivery schemes that fairly share the available network bandwidth with reliable data protocols such as TCP. This paper proposes a new flow and congestion control scheme, SCP (streaming control protocol), for real- time streaming of continuous multimedia data across the Internet. The design of SCP arose from several years of experience in building and using adaptive real-time streaming video players. SCP addresses two issues associated with real- time streaming. First, it uses a congestion control policy that allows it to share network bandwidth fairly with both TCP and other SCP streams. Second, it improves smoothness in streaming and ensures low, predictable latency. This distinguishes it from TCP's jittery congestion avoidance policy that is based on linear growth and one-half reduction of its congestion window. In this paper, we present a description of SCP, and an evaluation of it using Internet- based experiments.

  7. 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.

  8. 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.

  9. PVM and IP multicast

    SciTech Connect

    Dunigan, T.H.; Hall, K.A.

    1996-12-01

    This report describes a 1994 demonstration implementation of PVM that uses IP multicast. PVM`s one-to-many unicast implementation of its pvm{_}mcast() function is replaced with reliable IP multicast. Performance of PVM using IP multicast over local and wide-area networks is measured and compared with the original unicast implementation. Current limitations of IP multicast are noted.

  10. 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.

  11. 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.

  12. Analysis of random drop for gateway congestion control. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Hashem, Emam Salaheddin

    1989-01-01

    Lately, the growing demand on the Internet has prompted the need for more effective congestion control policies. Currently No Gateway Policy is used to relieve and signal congestion, which leads to unfair service to the individual users and a degradation of overall network performance. Network simulation was used to illustrate the character of Internet congestion and its causes. A newly proposed gateway congestion control policy, called Random Drop, was considered as a promising solution to the pressing problem. Random Drop relieves resource congestion upon buffer overflow by choosing a random packet from the service queue to be dropped. The random choice should result in a drop distribution proportional to the bandwidth distribution among all contending TCP connections, thus applying the necessary fairness. Nonetheless, the simulation experiments demonstrate several shortcomings with this policy. Because Random Drop is a congestion control policy, which is not applied until congestion has already occurred, it usually results in a high drop rate that hurts too many connections including well-behaved ones. Even though the number of packets dropped is different from one connection to another depending on the buffer utilization upon overflow, the TCP recovery overhead is high enough to neutralize these differences, causing unfair congestion penalties. Besides, the drop distribution itself is an inaccurate representation of the average bandwidth distribution, missing much important information about the bandwidth utilization between buffer overflow events. A modification of Random Drop to do congestion avoidance by applying the policy early was also proposed. Early Random Drop has the advantage of avoiding the high drop rate of buffer overflow. The early application of the policy removes the pressure of congestion relief and allows more accurate signaling of congestion. To be used effectively, algorithms for the dynamic adjustment of the parameters of Early Random Drop

  13. Enhanced TCP Congestion Control with Higher Utilization in Under-Buffered Links

    NASA Astrophysics Data System (ADS)

    Hyun, Dowon; Jang, Ju Wook

    TCP Reno is not fully utilized in under-buffered links. We propose a new TCP congestion control algorithm that can utilize the link almost up to 100% except the first congestion avoidance cycle. Our scheme estimates the minimum congestion window size for full link utilization in every congestion avoidance cycle and sends extra packets without touching TCP Reno congestion control. It has the same RTT fairness and the same saw-tooth wave as TCP Reno does. Our scheme does not affect competing TCP Reno flows since it uses only unused link capacity. We provide a simple mathematical modeling as well as ns-2 simulation results which show that the link utilization is improved by up to 19.88% for k=1/8 against TCP Reno when the buffer is k times the optimal buffer size. We claim that our scheme is useful for transmitting large amount of data in under-buffered links.

  14. 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.

  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. Optimal resource allocation for multicast sessions in multi-hop wireless networks.

    PubMed

    Bui, Loc; Srikant, R; Stolyar, Alexander

    2008-06-13

    In this paper, we extend recent results on fair and stable resource allocation in wireless networks to include multicast sessions, in particular multi-rate multicast. The solution for multi-rate multicast is based on scheduling virtual (shadow) 'traffic' that 'moves' in reverse direction from destinations to sources. This shadow scheduling algorithm can also be used to control delays in wireless networks.

  17. Hysteresis-based congestion control at the B-ISDN access

    NASA Astrophysics Data System (ADS)

    Wissing, Johannes

    1993-11-01

    Multiplexing of bursty sources and refined congestion control strategies are still the subject of numerous research activities. Broadband applications with very high peak-to-mean bitrate ratio and long silence periods like still picture video gave rise to different ideas of rate control at the B-ISDN network access. Contributions on Input Rate Control for source coded traffic as well as on Server Rate Control within a LAN/ATM Interworking Unit have recently been presented. This paper addresses a congestion avoidance strategy at the network access regarding the aggregated traffic of bursty sources. Depending on the number of active sources as well as on certain defined congestion levels the cell rate at the network access is controlled. The proposed analytical approach is based on the model of uniform and continuous arrival and service. The selected underlying Markov chain contains `split' states in order to handle the congestion correlation. The proposed model is extended to an adaptive Non-Markov system where the buffer filling level is evaluated using a switching hysteresis. This type of congestion measurement turns out to be very useful for an adaptive rate control mechanism that guarantees a certain quality of service while still achieving a good statistical gain. The analytical approach is confirmed by results of a computer simulation that is extended to the more complex case of adaptive rate control.

  18. Adaptive-compression based congestion control technique for wireless sensor networks.

    PubMed

    Lee, Joa-Hyoung; Jung, In-Bum

    2010-01-01

    Congestion in a wireless sensor network causes an increase in the amount of data loss and delays in data transmission. In this paper, we propose a new congestion control technique (ACT, Adaptive Compression-based congestion control Technique) based on an adaptive compression scheme for packet reduction in case of congestion. The compression techniques used in the ACT are Discrete Wavelet Transform (DWT), Adaptive Differential Pulse Code Modulation (ADPCM), and Run-Length Coding (RLC). The ACT first transforms the data from the time domain to the frequency domain, reduces the range of data by using ADPCM, and then reduces the number of packets with the help of RLC before transferring the data to the source node. It introduces the DWT for priority-based congestion control because the DWT classifies the data into four groups with different frequencies. The ACT assigns priorities to these data groups in an inverse proportion to the respective frequencies of the data groups and defines the quantization step size of ADPCM in an inverse proportion to the priorities. RLC generates a smaller number of packets for a data group with a low priority. In the relaying node, the ACT reduces the amount of packets by increasing the quantization step size of ADPCM in case of congestion. Moreover, in order to facilitate the back pressure, the queue is controlled adaptively according to the congestion state. We experimentally demonstrate that the ACT increases the network efficiency and guarantees fairness to sensor nodes, as compared with the existing methods. Moreover, it exhibits a very high ratio of the available data in the sink. PMID:22319280

  19. Adaptive-Compression Based Congestion Control Technique for Wireless Sensor Networks

    PubMed Central

    Lee, Joa-Hyoung; Jung, In-Bum

    2010-01-01

    Congestion in a wireless sensor network causes an increase in the amount of data loss and delays in data transmission. In this paper, we propose a new congestion control technique (ACT, Adaptive Compression-based congestion control Technique) based on an adaptive compression scheme for packet reduction in case of congestion. The compression techniques used in the ACT are Discrete Wavelet Transform (DWT), Adaptive Differential Pulse Code Modulation (ADPCM), and Run-Length Coding (RLC). The ACT first transforms the data from the time domain to the frequency domain, reduces the range of data by using ADPCM, and then reduces the number of packets with the help of RLC before transferring the data to the source node. It introduces the DWT for priority-based congestion control because the DWT classifies the data into four groups with different frequencies. The ACT assigns priorities to these data groups in an inverse proportion to the respective frequencies of the data groups and defines the quantization step size of ADPCM in an inverse proportion to the priorities. RLC generates a smaller number of packets for a data group with a low priority. In the relaying node, the ACT reduces the amount of packets by increasing the quantization step size of ADPCM in case of congestion. Moreover, in order to facilitate the back pressure, the queue is controlled adaptively according to the congestion state. We experimentally demonstrate that the ACT increases the network efficiency and guarantees fairness to sensor nodes, as compared with the existing methods. Moreover, it exhibits a very high ratio of the available data in the sink. PMID:22319280

  20. Extended weighted fair queuing (EWFQ) algorithm for broadband applications including multicast traffic

    NASA Astrophysics Data System (ADS)

    Tufail, Mudassir; Cousin, Bernard

    1997-10-01

    Ensuring end-to-end bounded delay and fair allocation of bandwidth to a backlogged session are no more the only criterias for declaring a queue service scheme good. With the evolution of packet-switched networks, more and more distributed and multimedia applications are being developed. These applications demand that service offered to them should be homogeneously distributed at all instants contrarily to back-to-back packet's serving in WFQ scheme. There are two reasons for this demand of homogeneous service: (1) In feedback based congestion control algorithms, sources constantly sample the network state using the feedback from the receiver. The source modifies its emission rate in accordance to the feedback message. A reliable feedback message is only possible if the packet service is homogeneous. (2) In multicast applications, where packet replication is performed at switches, replicated packets are probable to be served at different rates if service to them, at different output ports, is not homogeneous. This is not desirable for such applications as the phenomena of packet replication to different multicast branches, at a switch, has to be carried out at a homogeneous speed for the following two important reasons: (1) heterogeneous service rates of replicated multicast packets result in different feedback informations, from different destinations (of same multicast session), and thus lead to unstable and less efficient network control. (2) in a switch architecture, the buffer requirement can be reduced if replication and serving of multicast packets are done at a homogeneous rate. Thus, there is a need of a service discipline which not only serve the applications at no less than their guaranteed rates but also assures a homogeneous service to packets. The homogeneous service to an application may precisely be translated in terms of maintaining a good inter-packets spacing. EWFQ scheme is identical to WFQ scheme expect that a packet is stamped with delayed

  1. Internet video transmission via receiver-based congestion control mechanism (RCCM) and H.263+ frame rate control

    NASA Astrophysics Data System (ADS)

    Kim, Young-Gook; Song, Hwangjun; Chung, Yon J.; Kim, JongWon; Kuo, C.-C. Jay

    1999-10-01

    A feedback-based Internet video transmission scheme based on the ITU-T H.263+ is presented. The proposed system is capable of continually adjusting the stream size to avoid the congestion in response to network condition changes. It consists of several major components such as TCP-friendly end- to-end congestion control with available bandwidth estimation, encoding frame rate control and transmission buffer smoothing at the server. These components are designed to meet the low computational complexity requirement so that the whole system can operate in real time. Among these, video-aware congestion control, which is called the receiver-based congestion control mechanism (RCCM), and the variable frame rate H.263+ encoding are the two key features. Through a seamless integration of these feature components, it is demonstrated that network adaptivity is enhanced to mitigate the packet loss and the bandwidth fluctuation, resulting in a smoother video experience at the receiver.

  2. Multi-time-scale congestion control mechanism based on the alpha-stable self-similar processes

    NASA Astrophysics Data System (ADS)

    Ge, Xiaohu; Zhu, Guangxi; Zhu, Yaoting; Shi, Chunyan

    2004-04-01

    A multi-time scale congestion control mechanism has been proposed in this paper, which utilizes the characteristic of self-similar in the network. Based on the theory of the alpha-stable processes, a prediction model is brought forward and a frame of multi-time scale is designed. The aim of all of those is try to avoid the congestion of network in statistically. Moreover, the frame of the new congestion control mechanism is described and the working procedure of the new congestion control mechanism is explained.

  3. 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

  4. CRRT: Congestion-Aware and Rate-Controlled Reliable Transport in Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Alam, Muhammad Mahbub; Hong, Choong Seon

    For successful data collection in wireless sensor networks, it is important to ensure that the required delivery ratio is maintained while keeping a fair rate for every sensor. Furthermore, emerging high-rate applications might require complete reliability and the transfer of large volume of data, where persistent congestion might occur. These requirements demand a complete but efficient solution for data transport in sensor networks which reliably transports data from many sources to one or more sinks, avoids congestion and maintains fairness. In this paper, we propose congestion-aware and rate-controlled reliable transport (CRRT), an efficient and low-overhead data transport mechanism for sensor networks. CRRT uses efficient MAC retransmission to increase one-hop reliability and end-to-end retransmission for loss recovery. It also controls the total rate of the sources centrally, avoids the congestion in the bottleneck based on congestion notifications from intermediate nodes and centrally assigns the rate to the sources based on rate assignment policy of the applications. Performance of CRRT is evaluated in NS-2 and simulation results demonstrate the effectiveness of CRRT.

  5. 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. PMID:26504898

  6. 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.

  7. Hopf bifurcation control in a congestion control model via dynamic delayed feedback.

    PubMed

    Guo, Songtao; Feng, Gang; Liao, Xiaofeng; Liu, Qun

    2008-12-01

    A typical objective of bifurcation control is to delay the onset of undesirable bifurcation. In this paper, the problem of Hopf bifurcation control in a second-order congestion control model is considered. In particular, a suitable Hopf bifurcation is created at a desired location with preferred properties and a dynamic delayed feedback controller is developed for the creation of the Hopf bifurcation. With this controller, one can increase the critical value of the communication delay, and thus guarantee a stationary data sending rate for larger delay. Furthermore, explicit formulae to determine the period and the direction of periodic solutions bifurcating from the equilibrium are obtained by applying perturbation approach. Finally, numerical simulation results are presented to show that the dynamic delayed feedback controller is efficient in controlling Hopf bifurcation.

  8. 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.

  9. A neural-fuzzy system for congestion control in ATM networks.

    PubMed

    Lee, S J; Hou, C L

    2000-01-01

    We propose the use of a neural-fuzzy scheme for rate-based feedback congestion control in asynchronous transfer mode (ATM) networks. Available bit rate (ABR) traffic is not guaranteed quality of service (QoS) in the setup connection, and it can dynamically share the available bandwidth. Therefore, congestion can be controlled by regulating the source rate, to a certain degree, according to the current traffic flow. Traditional methods perform congestion control by monitoring the queue length. The source rate is decreased by a fixed rate when the queue length is greater than a prespecified threshold. However, it is difficult to get a suitable rate according to the degree of traffic congestion. We employ a neural-fuzzy mechanism to control the source rate. Through learning, membership values can be generated and cell loss can be predicted from the status of the queue length. Then, an explicit rate is calculated and the source rate is controlled appropriately. Simulation results have shown that our method is effective compared with traditional methods.

  10. Decoupling congestion control and error control mechanisms in TCP and evaluating their performance over broadband satellite networks

    NASA Astrophysics Data System (ADS)

    Wang, Lina; Gu, Xuemai

    2004-04-01

    In this paper, we propose a novel method to better evaluate the performance of TCP over broadband satellite networks. We decouple the most crucial parts of TCP that impact its performance in broadband satellite environments, namely congestion control and error control mechanisms. And then we re-design these two function blocks and make them become two individual parts. With these re-designed modules, we have investigated the interactions between various currently existing TCP congestion control and error control schemes, as well as their impact on TCP performance over a geostationary broadband satellite link with long propagation delay and high bit error rate. Simulation results have shown that some combinations of different congestion control and error control mechanisms can waste satellite link bandwidth with large numbers of retransmission packets and unnecessary retransmission packets. And the modified TCP NewReno implementation can avoid high amount of retransmissions and unnecessary retransmissions.

  11. 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.

  12. Evaluation of ABR traffic control schemes for ATM LAN and WAN: effects of congestion indication schemes and ER switch algorithms

    NASA Astrophysics Data System (ADS)

    Moh, W. Melody; Shenoy, Sandeep

    1997-10-01

    The ATM Forum has adopted rate-based congestion control for ABR (available bit rate) traffic. Much of the existing work evaluating ABR congestion control schemes has used some threshold value on buffer queue length to indicate congestion. On the other hand, many ER (explicit rate) algorithms calculate their 'fair-share' values based on utilization level, with the assumption that ER switches are able to measure the current utilization level of ABR traffic. If one would use the same mechanism -- measuring utilization level -- to indicate congestion, then the same switch could easily implement both binary and ER ABR control algorithms. Based on the above observations, in this paper we study the effect of using two different congestion indication methods: (1) buffer queue length (the most commonly used method); and (2) utilization level (the new method). We evaluate two binary ABR control schemes: EFCI (explicit forward congestion indication) and CI (congestion indication) using backward notification, using the two different congestion methods. We also evaluate and compare two ER algorithms: the ERICA (explicit rate indication for congestion avoidance) algorithm proposed by Jain and the CAPC-2 (congestion avoidance with proportional control - 2) algorithm proposed by Barnhart. Performance evaluation are carried out by computer simulation. We simulate two ABR switches connected by an OC-3 link, with each switch connecting five end-systems. The distance between the two switches are 20 km for LAN and 1,000 km for WAN, based on ATM forum specification. For each simulation run, we measure average queuing delay, maximum queue length, and network utilization. Traces of ACR (allowed cell rate) and buffer queue length are also examined. We found that using the new congestion method indication dramatically reduces the maximum queue length and average queuing delay, with a slight decrease in utilization. Both ER schemes show smooth buffer occupancy and attain high utilization.

  13. 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.

  14. 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.

  15. 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.

  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. 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

  18. 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

  19. Ameliorating TCP congestion control for improving TCP reliability over wireless networks

    NASA Astrophysics Data System (ADS)

    Xu, Chang-biao; Long, Ke-ping; Xian, Yong-ju

    2004-04-01

    TCP congestion control mechanism, being based on the presupposition that network congestion is the only reason for data loss, is suitable for wired environments rather than for wireless environments with characteristics of higher bit error rate, lower bandwidth, longer delay, frequent mobility and so on, where link corruption can also cause data loss. To avoid unnecessary decrease of packet sending rate resulting in lower throughput and longer delay, some improved TCP congestion mechanisms have been presented. However, one of the disadvantages of these mechanisms is that a great deal of unnecessary packets lost by corruption can be caused while heavy data loss rate by corruption lasts short time. As well known, energy consumption of mobile hosts is one of the most important factors for wireless communication. How to save energy of mobile host has become an important task for wireless communication. One of the methods is to improve reliability to decrease overheads resulting from re-transmitting lost data. Obviously, it is necessary to decrease data sending rate, but how does it do? This paper answers the question, and then presents an improved TCP congestion control mechanism, namely TCP_IR (TCP for Improving Reliability) whose implementations are based on two algorithms. Algorithm I-based TCP_IR is driven by data sending periodic, while algorithm II-based TCP_IR is driven by the event of data lost by corruption. They can be very easily implemented with fewer overheads and can effectively improve TCP reliability with light influence to throughput and delay. The paper"s contribution is to give valuable references to further study TCP in wireless networks.

  20. Congestion Control in TCP/AQM Networks Using a Disturbance Observer

    NASA Astrophysics Data System (ADS)

    Kubo, Ryogo; Kani, Junichi; Fujimoto, Yukihiro

    This paper presents a novel congestion controller for transmission control protocol/active queue management (TCP/AQM) networks. In order to maintain the queue length to a value less than the buffer size at the aggregation nodes, the queue management mechanism drops some packets depending on the probability calculated by a congestion controller. However, conventional controllers such as random early detection (RED) algorithms and proportional-integral-derivative (PID)-based controllers are not compatible with parameter variation in TCP/AQM networks. Parameter variation in TCP/AQM networks includes the change of the number of TCP connections, the inflow of user datagram protocol (UDP) flows and so on. In the proposed method, the effect of parameter variation is estimated as drop probability disturbance by using a disturbance observer (DOB). By using the DOB, disturbance suppression characteristics of the controlled system can be drastically improved. In addition, the TCP/AQM network system is analyzed on the basis of an acceleration control scheme. The proposed method is validated by simulation studies performed using a nonlinear model of a TCP/AQM network and verifications made using the network simulator ns-2.

  1. 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.

  2. 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.

  3. Congestion Avoidance Control through Non-cooperative Games between Customers and Service Providers

    NASA Astrophysics Data System (ADS)

    Charilas, Dimitris E.; Panagopoulos, Athanasios D.; Vlacheas, Panagiotis; Markaki, Ourania I.; Constantinou, Philip

    Congestion avoidance control refers to controlling the load of the network by restricting the admission of new user’s sessions and resolving the unwanted overload situations. Admission control and Load control constitute key mechanisms regarding Radio Resource Management. As the wireless world is moving towards heterogeneous wireless networks, these types of control are facing more challenges, since efficiency and fairness are required. Game theory provides an appropriate framework for formulating fair and efficient congestion avoidance control problems. In this paper we formulate a non-cooperative game between service providers and customers. On the one hand, the service providers wish to maximize their revenue, but on the other hand, the users wish to maximize the quality of service received, keeping at the same time the expenses as low as possible. Therefore a balance has to be established among these contradictory demands. Our effort also concentrates in the proper modeling of the user’s level of satisfaction, so as to provide a logical decision-taking framework. The proposed scheme is then tested using the ns2 simulator. Results show that both parties can benefit from this mechanism.

  4. Congestion control for ATM multiplexers using neural networks: multiple sources/single buffer scenario.

    PubMed

    Du, Shu-xin; Yuan, Shi-yong

    2004-09-01

    A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate. The control methods not only minimize the cell loss rate but also guarantee the quality of information (such as voice sources) fed into the multiplexer buffer. Simulations with 150 ADPCM voice sources fed into the multiplexer buffer showed that the proposed methods have advantage over the previous methods in the aspect of the performance indices such as cell loss rate (CLR) and voice quality. PMID:15323008

  5. 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.

  6. 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

  7. 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. PMID:25177722

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Liu, Gongliang; Gu, Xuemai; Li, Shizhong

    2005-11-01

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

  10. 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.

  11. 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.

  12. 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)

  13. Transportation network policy modeling for congestion and pollution control: A variational inequality approach

    NASA Astrophysics Data System (ADS)

    Ramanujam, Padma

    1999-08-01

    Public concern over the state of the environment has grown over the past decade. All indications are that this concern will continue to influence policy making into the foreseeable future. Road transport is seen as the major contributor to environmental degradation. Transportation planners around the world face the question: cleaner air and/or faster commutes? While individual vehicles can be made more environmentally friendly, the sheer scale of growth in world-wide vehicle numbers is projected to cause significant environmental degradation in the longer run, and in the absence of newer and stricter polices. It is a challenge for governments to find policies that ensure congestion-free metropolitan areas while guaranteeing both critical environmental quality levels and a sufficient infrastructure access to all groups involved. The objective of the dissertation is to provide a mathematical framework to study transportation policy models for the purpose of controlling congestion and pollution. Towards this objective. a series of transportation policy models are developed to study travel behavior and to quantity the reductions in congestion and automobile emissions. The dissertation begins with a brief historical overview of some of the pioneering works in urban transportation economics and later presents the theoretical foundation for the transportation policy models developed. The dissertation introduces single modal and multimodal transportation network policy models that accomplish road pricing with the imposition of goal targets on link loads. as well as, integrated traffic equilibrium models with marketable mobile emission permits. Furthermore, equilibrium conditions are derived for each model, and both qualitative analysis and computational procedures are studied. Finally, the dissertation concludes with a comparative study of the relationship between regulatory pricing models and marketable emission permit transportation models and a discussion on key factors

  14. 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.

  15. Congestive Heart Failure and Diabetes: Balancing Glycemic Control with Heart Failure Improvement

    PubMed Central

    Nasir, Saifullah; Aguilar, David

    2012-01-01

    Diabetes and congestive heart failure (HF) commonly coexist in the same patient, and the presence of diabetes in HF patients is associated with increased adverse events compared to patients without diabetes. Recent guidelines regarding glycemic control stress individualization of glycemic therapy based on patient comorbid conditions and potential adverse effects of medical therapy. This balance in glycemic control may be particularly relevant in patients with diabetes and HF. In this review, we address data regarding the influence that certain HF medications may have on glycemic control. Despite potential modest changes in glycemic control, clinical benefits of proven pharmacologic HF therapies extend to patients with diabetes and HF. In addition, we review potential benefits and challenges associated with commonly used glycemic medications in HF patients. Finally, recent data and controversies on optimal glycemic targets in HF patients are discussed. Given the large number of patients with diabetes and HF and the health burden of these conditions, much needed future work is necessary to define the optimal glycemic treatment in HF patients with diabetes. PMID:23062568

  16. Hopf bifurcation and uncontrolled stochastic traffic-induced chaos in an RED-AQM congestion control system

    NASA Astrophysics Data System (ADS)

    Wang, Jun-Song; Yuan, Rui-Xi; Gao, Zhi-Wei; Wang, De-Jin

    2011-09-01

    We study the Hopf bifurcation and the chaos phenomena in a random early detection-based active queue management (RED-AQM) congestion control system with a communication delay. We prove that there is a critical value of the communication delay for the stability of the RED-AQM control system. Furthermore, we show that the system will lose its stability and Hopf bifurcations will occur when the delay exceeds the critical value. When the delay is close to its critical value, we demonstrate that typical chaos patterns may be induced by the uncontrolled stochastic traffic in the RED-AQM control system even if the system is still stable, which reveals a new route to the chaos besides the bifurcation in the network congestion control system. Numerical simulations are given to illustrate the theoretical results.

  17. 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.

  18. Adaptive Directional Multicast Scheme in mmWave WPANs with Directional Antennas

    NASA Astrophysics Data System (ADS)

    Shin, Kyungchul; Kim, Youngsun; Kang, Chul-Hee

    This letter considers problems with an efficient link layer multicasting technique in a wireless personal area network environment using a directional antenna. First, we propose an adaptive directional multicast scheme (ADMS) for delay-sensitive applications in mmWave WPAN with directional antenna. Second, the proposed ADMS aims to improve throughput as well as satisfy the application-specific delay requirements. We evaluate the performances of legacy Medium Access Control, Life Centric Approach, and adaptive directional multicast schemes via QualNet 5.0. Our results show that the proposed scheme provides better performance in terms of total network throughput, average transmission time, packet delivery ratio and decodable frame ratio.

  19. 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.

  20. Network congestion can be controlled: Routing algorithms in optical networks and Ethernets

    SciTech Connect

    Goldberg, L.A.; MacKenzie, P.D.; Greenberg, D.S.

    1997-12-01

    Congestion and contention can greatly reduce the effective performance of an interconnection network. This report gathers together research done under a Laboratory Research and Development Program (LDRD) project at Sandia National Laboratories. The goal of the project was to explore the contention properties of novel optical interconnects. In the process of exploring optical interconnects the project also gained new insights into the use of backoff protocols in the current dominant interconnect technology, Ethernet.

  1. Nonlinear dynamics of internet congestion control: A frequency-domain approach

    NASA Astrophysics Data System (ADS)

    Gentile, Franco S.; Moiola, Jorge L.; Paolini, Eduardo E.

    2014-04-01

    In this paper a fluid-flow model for TCP congestion avoidance combined with different AQM schemes is analyzed. The conditions for the appearance of Hopf bifurcations are stated analytically using frequency-domain techniques. The proposed methodology allows the characterization of the emerging periodic orbits, providing approximations of their amplitude and frequency. In addition, multiple oscillations and limit cycle bifurcations are found via numerical tools.

  2. 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.

  3. 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

  4. Key management approach of multicast

    NASA Astrophysics Data System (ADS)

    Jiang, Zhen; Wang, Xi-lian; Zhang, Hong-ke; Zhang, Li-yong

    2002-09-01

    A key management approach of multicast is provided in this paper. It is based on the approach of assignment key to every group member through key center. In view of some management schemes where members join, leave or are deleted, key service center must distribute new key through unicast another time. The bigger amount of members the greater expenses will be spent. In this paper with member varying their upper key service center still distribute the new keythrough multicast and an ID is assigned to every member to identify their transmission message so as to implement data origin authentication. The essential principle of this approach is distributing a key generator for each member. For example a random number generator depending on certain algorithm can be distributed. And every member needs store a seed table. In this project key can automatically be renewed as time goes by or immediately renewed. Replace unicast by multicast to renew key decrease the spending. It is not only suitable for the key centralized management scheme with fewer members but also for the key separated management scheme with large group members and member frequently changed.

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

    NASA Astrophysics Data System (ADS)

    Liu, Huanlin; Zhou, Bangtao; Chen, Yong

    2014-12-01

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

  6. Routing in DiffServ multicast environment

    NASA Astrophysics Data System (ADS)

    Verma, Shekhar

    2002-07-01

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

  7. 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.

  8. Multicast Reduction Network Source Code

    SciTech Connect

    Lee, G.

    2006-12-19

    MRNet is a software tree-based overlay network developed at the University of Wisconsin, Madison that provides a scalable communication mechanism for parallel tools. MRNet, uses a tree topology of networked processes between a user tool and distributed tool daemons. This tree topology allows scalable multicast communication from the tool to the daemons. The internal nodes of the tree can be used to distribute computation and alalysis on data sent from the tool daemons to the tool. This release covers minor implementation to port this software to the BlueGene/L architecuture and for use with a new implementation of the Dynamic Probe Class Library.

  9. 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.

  10. Fragmentation-aware service provisioning for advance reservation multicast in SD-EONs.

    PubMed

    Li, Shengru; Lu, Wei; Liu, Xiahe; Zhu, Zuqing

    2015-10-01

    In this paper, we study the service provisioning schemes for dynamic advance reservation (AR) multicast requests in elastic optical networks (EONs). We first propose several algorithms that can handle the service scheduling and routing and spectrum assignment (RSA) of AR multicast requests jointly, including an integrated two-dimensional fragmentation-aware RSA (2D-FMA) that can alleviate the 2D fragmentation caused by light-tree provisioning. Then, we leverage the idea of software-defined EONs (SD-EONs) that utilizes OpenFlow (OF) in the control plane to demonstrate and evaluate the proposed algorithms. Specifically, we build an SD-EON control plane testbed, implement the algorithms in it, and perform control plane experiments on dynamic AR multicast provisioning. The results indicate that 2D-FMA achieves the best blocking performance and provides the shortest average setup delay.

  11. 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.

  12. 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.

  13. Multicast Reduction Network Source Code

    2006-12-19

    MRNet is a software tree-based overlay network developed at the University of Wisconsin, Madison that provides a scalable communication mechanism for parallel tools. MRNet, uses a tree topology of networked processes between a user tool and distributed tool daemons. This tree topology allows scalable multicast communication from the tool to the daemons. The internal nodes of the tree can be used to distribute computation and alalysis on data sent from the tool daemons to themore » tool. This release covers minor implementation to port this software to the BlueGene/L architecuture and for use with a new implementation of the Dynamic Probe Class Library.« less

  14. Analyzing and designing of reliable multicast based on FEC in distributed switch

    NASA Astrophysics Data System (ADS)

    Luo, Ting; Yu, Shaohua; Wang, Xueshun

    2008-11-01

    AS businesses become more dependent on IP networks, lots of real-time services are adopted and high availability in networks has become increasingly critical. With the development of carrier grade ethernet, the requirements of high speed metro ethernet device are more urgently. In order to reach the capacity of hundreds of Gbps or Tbps, most of core ethernet switches almost adopted distributed control architecture and large capacity forwarding fabric. When distributed switch works, they always have one CE and many FE. There for, it shows the feature of multicast with one sender and many receivers. It is deserved research for us how to apply reliable multicast to distributed switch inner communication system. In this paper, we present the general architecture of a distributed ethernet switch, focusing on analysis the model of internal communication subsystem. According to its character, a novel reliable multicast communication mechanism based on FEC recovery algorithm has been applied and evaluated in experiment.

  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. 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.

  17. Integrated nonlinear interferometer with wavelength multicasting functionality.

    PubMed

    Yang, Weili; Yu, Yu; Zhang, Xinliang

    2016-08-01

    Nonlinear interference based on four wave mixing (FWM) is extremely attractive due to its phase sensitivity. On the other hand, wavelength multicasting, which supports data point-to-multipoint connections, is a key functionality to increase the network efficiency and simplify the transmitter and receiver in the wavelength-division multiplexing systems. We propose and experimentally demonstrate a nonlinear interferometer with wavelength multicasting functionality based on single-stage FWM in an integrated silicon waveguide. With a three-pump and dual-signal input, four phase sensitive idlers are obtained at the interferometer output. For a proof-of-concept application, we further theoretically demonstrate the multicasting logic exclusive-OR (XOR) gate for both intensity and phase modulated signals. The proposed scheme would be potentially applied in various on-chip applications for future optical communication system. PMID:27505786

  18. Network coding for quantum cooperative multicast

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Chen, Xiu-Bo; Li, Jing; Wang, Cong; Yang, Yi-Xian; Li, Zongpeng

    2015-11-01

    Cooperative communication is starting to attract substantial research attention in quantum information theory. However, given a specific network, it is still unknown whether quantum cooperative communication can be successfully performed. In this paper, we investigate network coding for quantum cooperative multicast (QCM) over the classic butterfly network. A very reasonable definition of QCM is first introduced. It not only perfectly focuses on the basic idea of quantum cooperative communication, but also wonderfully reflects the characteristic of classical multicast over a specific network structure. Next, we design QCM protocol for two-level systems and generalize the protocol into d-dimensional Hilbert space. It is shown that our protocols have significant advantages in terms of resource cost and compatibility with classical multicast. Besides, the success probability, which only depends on the coefficients of the initial quantum states, is carefully analyzed. In particular if the source nodes choose the quantum equatorial states, success probability can reach 1.

  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. 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.

  1. Recursive pump-adding scheme for optical superchannel multicasting based on FWM

    NASA Astrophysics Data System (ADS)

    Zhu, Paikun; Li, Juhao; Wu, Zhongying; Chen, Xin; Xu, Yingying; Lin, Bangjiang; Chen, Zhangyuan; He, Yongqi

    2015-07-01

    Optical superchannel multicasting, whereby a superchannel is replicated simultaneously to multiple spectral locations in a single device, is potentially a promising functionality for future optical networks. Multiple-pump four-wave mixing (FWM) in highly nonlinear fiber (HNLF) is an effective approach to implement superchannel multicasting. However, if the frequencies of the pumps are not carefully configured, the generated replicas would be spectrally scattered, which would increase the difficulty of controlling replicas' performance and managing spectral resource. In this paper, we propose a recursive pump-adding (RPA) scheme, which makes the replicas more spectrally aggregated than our previous exponentially-growing-spaced (EGS) pump scheme. Such replica aggregation technique can reduce phase mismatching of replicas remote from the original channel, which is beneficial to replicas' performance. RPA scheme also provides an additional option of replica allocation for multicasting. Based on the RPA scheme, we have experimentally demonstrated 1-to-21 superchannel multicasting with 5 pumps. More than 2.3 dB Q-factor margin is achieved across all the replicas compared with the typical 7% forward error correction (FEC) threshold. The performance comparison between RPA and EGS pump scheme is also investigated.

  2. 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.

  3. Delivering Faster Congestion Feedback with the Mark-Front Strategy

    NASA Technical Reports Server (NTRS)

    Liu, Chunlei; Jain, Raj

    2001-01-01

    Computer networks use congestion feedback from the routers and destinations to control the transmission load. Delivering timely congestion feedback is essential to the performance of networks. Reaction to the congestion can be more effective if faster feedback is provided. Current TCP/IP networks use timeout, duplicate Acknowledgement Packets (ACKs) and explicit congestion notification (ECN) to deliver the congestion feedback, each provides a faster feedback than the previous method. In this paper, we propose a markfront strategy that delivers an even faster congestion feedback. With analytical and simulation results, we show that mark-front strategy reduces buffer size requirement, improves link efficiency and provides better fairness among users. Keywords: Explicit Congestion Notification, mark-front, congestion control, buffer size requirement, fairness.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Multi-area layered multicast scheme for MPLS networks

    NASA Astrophysics Data System (ADS)

    Ma, Yajie; Yang, Zongkai; Wang, Yuming; Chen, Jingwen

    2005-02-01

    Multi-protocol label switching (MPLS) is multiprotocols both at layer 2 and layer 3. It is suggested to overcome the shortcomings of performing complex longest prefix matching in layer 3 routing by using short, fixed length labels. The MPLS community has put more effort into the label switching of unicast IP traffic, but less in the MPLS multicast mechanism. The reasons are the higher label consumption, the dynamical mapping of L3 multicast tree to L2 LSPs and the 20-bit shim header which is much fewer than the IPv4 IP header. On the other hand, heterogeneity of node capability degrades total performance of a multicast group. In order to achieve the scalability as well as the heterogeneity in MPLS networks, a novel scheme of MPLS-based Multi-area Layered Multicast Scheme (MALM) is proposed. Unlike the existing schemes which focus on aggregating the multicast stream, we construct the multicast tree based on the virtual topology aggregation. The MPLS area is divided into different sub-areas to form the hierarchical virtual topology and the multicast group is reconstructed into multiple layers according to the node capability. At the same time, the label stack is used to save the label space. For stability of the MALM protocol, a multi-layer protection scheme is also discussed. The experiment results show that the proposed scheme saves label space and decrease the Multicast Forwarding Table in much degree.

  10. 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.

  11. Availability-guaranteed optical multicasting provisioning in WDM mesh networks

    NASA Astrophysics Data System (ADS)

    Zhang, Chunlei; Hu, Weisheng; Jin, Yaohui; Sun, Weiqiang; Zhu, Yi; Wei, Jianing

    2005-11-01

    Multicast applications have attracted more and more attention due to more efficient bandwidth usage and the increasing popularity of the point-multipoint multimedia applications. Optical multicasting outperforms the electronic multicasting in some aspects. Service level agreement (SLA) and quality of service (QoS) are important to service providers and users. Service providers always first maximize revenue to accept as many as connection requests as possible and then to minimize the capacity of all accepted connection. In this paper, the problem of cost-effective optical multicasting connection provisioning to satisfy the connections' availability requirements on a given physical topology is formally stated. We propose a mixed integer linear program (MILP) based approach for static multicast traffic. The feature of our algorithm lies on without considering any protection schemes, and when the system adapts dedicated protection or the sharing protection, the problem is more complicated.

  12. 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.

  13. An Economic Case for End System Multicast

    NASA Astrophysics Data System (ADS)

    Analoui, Morteza; Rezvani, Mohammad Hossein

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

  14. Optimal multicast communication in wormhole-routed torus networks

    SciTech Connect

    Robinson, D.F.; McKinley, P.K.; Cheng, B.H.C.

    1994-12-31

    This paper presents efficient algorithms that implement one-to-many, or multicast, communication in wormhole-routed torus networks. By exploiting the properties of the switching technology and the use of virtual channels, a minimum-time multicast algorithm is presented for n-dimensional torus networks that use deterministic, dimension-ordered routing of unicast messages. The algorithm can deliver a multicast message to m-1 destinations in [log{sub 2}m] message-passing steps, while avoiding contention among the constituent unicast messages. Performance results of a simulation study on torus networks are also given.

  15. Multicasting in Wireless Communications (Ad-Hoc Networks): Comparison against a Tree-Based Approach

    NASA Astrophysics Data System (ADS)

    Rizos, G. E.; Vasiliadis, D. C.

    2007-12-01

    We examine on-demand multicasting in ad hoc networks. The Core Assisted Mesh Protocol (CAMP) is a well-known protocol for multicast routing in ad-hoc networks, generalizing the notion of core-based trees employed for internet multicasting into multicast meshes that have much richer connectivity than trees. On the other hand, wireless tree-based multicast routing protocols use much simpler structures for determining route paths, using only parent-child relationships. In this work, we compare the performance of the CAMP protocol against the performance of wireless tree-based multicast routing protocols, in terms of two important factors, namely packet delay and ratio of dropped packets.

  16. Fingerprint multicast in secure video streaming.

    PubMed

    Zhao, H Vicky; Liu, K J Ray

    2006-01-01

    Digital fingerprinting is an emerging technology to protect multimedia content from illegal redistribution, where each distributed copy is labeled with unique identification information. In video streaming, huge amount of data have to be transmitted to a large number of users under stringent latency constraints, so the bandwidth-efficient distribution of uniquely fingerprinted copies is crucial. This paper investigates the secure multicast of anticollusion fingerprinted video in streaming applications and analyzes their performance. We first propose a general fingerprint multicast scheme that can be used with most spread spectrum embedding-based multimedia fingerprinting systems. To further improve the bandwidth efficiency, we explore the special structure of the fingerprint design and propose a joint fingerprint design and distribution scheme. From our simulations, the two proposed schemes can reduce the bandwidth requirement by 48% to 87%, depending on the number of users, the characteristics of video sequences, and the network and computation constraints. We also show that under the constraint that all colluders have the same probability of detection, the embedded fingerprints in the two schemes have approximately the same collusion resistance. Finally, we propose a fingerprint drift compensation scheme to improve the quality of the reconstructed sequences at the decoder's side without introducing extra communication overhead.

  17. 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.

  18. Oral amrinone for the treatment of chronic congestive heart failure: results of a multicenter randomized double-blind and placebo-controlled withdrawal study.

    PubMed

    DiBianco, R; Shabetai, R; Silverman, B D; Leier, C V; Benotti, J R

    1984-11-01

    A placebo-controlled study was employed to evaluate the effects of oral amrinone in patients with congestive heart failure. After a baseline period of at least 4 weeks of standard treatment for refractory congestive heart failure, oral amrinone was added to the treatment regimen of 173 patients. Patients were predominantly male (89%), aged 24 to 76 years (mean 54), with ischemic (52%) or idiopathic (37%) dilated cardiomyopathy, in New York Heart Association functional class II (40%), III (59%) and IV (1%) and having a mean (+/- standard deviation) left ventricular ejection fraction of 25 +/- 15%. Phase 1: After the addition of amrinone (113 +/- 33 mg three times daily), 52 patients (30%) showed a maximal increase in treadmill exercise time exceeding 2 minutes (Naughton protocol), 72 (42%) had a lesser increase, 24 (14%) developed limiting adverse reactions, 20 (12%) died and 5 dropped out of the study. Fifty-two "responders" (30%) who were free of limiting side effects and had a greater than 2 minute increase in exercise time were randomized in double-blind fashion to continued amrinone or switched to placebo (each plus standard treatment) for an additional 12 weeks. Phase 2: Comparison of 31 of these 52 responders who continued to receive amrinone with the remaining 21 randomized to placebo revealed no significant differences in vital signs, indexes of left ventricular size and function, systolic time intervals or maximal exercise time. Continued follow-up study of patients receiving either amrinone or placebo revealed decreases in exercise times of 7 and 10%, respectively (both p less than 0.05 compared with before randomization). Episodes of worsened congestive heart failure severe enough to mandate termination of double-blind treatment were as frequent in patients taking placebo (4[18%] of 21) as in those taking amrinone (4[13%] of 31; p = NS). The average symptom score and functional class of each treatment group remained comparable. Adverse effects such as

  19. 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.

  20. Proportional Fair Scheduling for Multicast Services in Wireless Cellular Networks

    NASA Astrophysics Data System (ADS)

    Koh, Chung Ha; Kim, Young Yong

    Recently, there has been extensive research on resource allocation schemes for multicast services that would satisfy the requirements of multimedia traffic. Although several schemes have been proposed to improve the performance of individual multicast groups, it is not easy to achieve both throughput efficiency and user fairness. In this study, we propose a new multicast scheduling scheme for achieving proportional fair (PF) allocation in wireless cellular systems. The basic idea of PF is to schedule the user whose corresponding instantaneous channel quality is the highest relative to the average channel condition over a given time scale. We first extend the PF metric to the extent that the scheduler can reflect the user's varying channel gain, and fairness, not only in the unicast case, but also in multicast transmissions. A multicast PF scheme maximizes the summation of the logarithmic average rate of all multicasting users. Thus, it improves the fairness to mobile users when compared to max-rate allocation, because the logarithmic rate gives more weight to lower rate users, while achieving high throughput. Moreover, the proposed scheme is less complex than max-rate allocation.

  1. 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

  2. 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.

  3. Applicability of explicit congestion notification in very high speed networks

    NASA Astrophysics Data System (ADS)

    Laalaoua, Rachid; Dotaro, Emmanuel; Atmaca, Tulin

    1999-11-01

    Congestion control avoidance in computer networks is still a major unresolved image. The applicability of previous congestion control mechanisms has to be demonstrated taking into account today's constraints. In this work, several schemes are studied in order to support differentiated services in a wide area, very high speed network.

  4. All optical wavelength multicaster and regenerator based on four-mode phase-sensitive parametric mixer.

    PubMed

    Liu, Lan; Temprana, Eduardo; Ataie, Vahid; Wiberg, Andreas O J; Kuo, Bill P-P; Myslivets, Evgeny; Alic, Nikola; Radic, Stojan

    2015-11-30

    Four-mode phase-sensitive (4MPS) process has been employed in a parametric mixer based wavelength multicaster, enhancing the multicasting conversion efficiency and signal-to-noise ratio. In addition, the 4MPS parametric multicaster is an outstanding candidate for all-optical regeneration, owing to its inherent capabilities to clamp amplitude fluctuations by the saturated parametric effect and to squeeze phase distortions by the phase sensitive process. The investigation in this paper focuses on the 4MPS multicaster operated in the saturation gain regime, including theoretical simulations and experimental demonstrations on amplitude and phase noise regeneration over 20 multicasting signal copies. PMID:26698727

  5. 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.

  6. 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.

  7. Congestion phenomenon analysis and delayed-feedback control in a modified coupled map traffic flow model containing the velocity difference

    NASA Astrophysics Data System (ADS)

    Fang, Ya-Ling; Shi, Zhong-Ke; Cao, Jin-Liang

    2015-06-01

    Based on the coupled map car-following model which was presented by Konishi et al. (1999), a modified coupled map car-following model is proposed. Specifically, the velocity difference between two successive vehicles is included in the model. The stability condition is given for the change of the speed of the preceding vehicle on the base of the control theory. We derive a condition under which the traffic jam never occurs in our model. Furthermore, in order to suppress traffic jams, we use static and dynamic version of decentralized delayed-feedback control for each vehicle, respectively, and provide a systematic procedure for designing the controller. In addition, the controller of each vehicle does not include any other vehicle information in real traffic flows.

  8. 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.

  9. Broadcast/multicast MPEG-2 video over wireless channels using header redundancy FEC strategies

    NASA Astrophysics Data System (ADS)

    Ma, Hairuo; El Zarki, Magda

    1999-01-01

    In this paper, we address the issue of error control in transmitting MPEG-2 encoded video streams over broadband fixed wireless access networks for broadcast or multicast services. Because of the error-prone nature of wireless channels, error control is mandatory when MPEG-2 video streams are transported over wireless access networks to end user. To prevent overloading the reliable wireline networks error control has to be applied locally. FEC is a must for broadcast or multicast services. Because of the important role of MPEG-2 control information in the decoding process, it must be given priority service in the form of excess error protection in order to achieve the desired QoS. In this paper, a header redundancy FEC (HRFEC) strategy is introduced and an implementation of it (type-I HRFEC scheme) is described. The overhead and delay jitter associated with the type-I HRFEC is also estimated. Simulation results on the performance of type-I HRFEC indicates that it improves the reception statistics of MPEG-2 control. As a direct, the quality, measured in terms of objective grade point and PSNR of the reconstructed video sequence, is improved.

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

    PubMed

    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.

  11. 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

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

    PubMed

    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

  13. Optimal software multicast in wormhole-routed multistage networks

    SciTech Connect

    Xu, H.; Gui, Y.D.; Ni, L.M.

    1994-12-31

    Multistage interconnection networks are a popular class of interconnection architecture for constructing scalable parallel computers (SPCs). The focus of this paper is on wormhole routed multistage networks supporting turnaround routing. Existing machines characterized by such a system model include the IBM SP-1, TMC CM-5, and Meiko CS-2. Efficient collective communication among processor nodes is critical to the performance of SPCS. A system-level multicast service, in which the same message is delivered from a source node to an arbitrary number of destination nodes, is fundamental in supporting collective communication primitives including the application-level broadcast, reduction, and barrier synchronization. This paper addresses how to efficiently implement multicast services in wormhole routed multistage networks, in the absence of hardware multicast support, by exploiting the properties of the switching technology. An optimal multicast algorithm is proposed. The results of implementations on a 64-node SP-1 show that the proposed algorithm significantly out performs the application-level broadcast primitives provided by currently existing collective communication libraries including the public domain MPI.

  14. 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.

  15. 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.

  16. 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).

  17. 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.

  18. 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.

  19. Vasomotor rhinitis: neglected cause of nasal congestion.

    PubMed

    Stewart, T W

    1980-01-01

    Vasomotor rhinitis is a condition of chronic nasal congestion which is noninfectious and nonallergic. Its cause is thought to be an imbalance of autonomic control to the nasal mucosa. This disorder is a diagnosis of exclusion, and other causes of chronic nasal obstruction must be considered first. Treatment measures include avoidance of nonspecific stimuli which exacerbate symptoms and, for symptomatic relief, use of oral sympathomimetics. Antihistamine-decongestant combinations may be effective in some patients. Topical vasoconstrictors should not be used.

  20. 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. PMID:27336405

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

    PubMed Central

    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. PMID:27336405

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    1998-10-01

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

  4. A Multicast Sparse-Grooming Algorithm Based on Network Coding in WDM Networks

    NASA Astrophysics Data System (ADS)

    Zhang, Shengfeng; Peng, Han; Sui, Meng; Liu, Huanlin

    2015-03-01

    To improve the limited number of wavelength utilization and decrease the traffic blocking probability in sparse-grooming wavelength-division multiplexing (WDM) networks, a multicast sparse-grooming algorithm based on network coding (MCSA-NC) is put forward to solve the routing problem for dynamic multicast requests in this paper. In the proposed algorithm, a traffic partition strategy, that the coarse-granularity multicast request with grooming capability on the source node is split into several fine-granularity multicast requests, is designed so as to increase the probability for traffic grooming successfully in MCSA-NC. Besides considering that multiple destinations should receive the data from source of the multicast request at the same time, the traditional transmission mechanism is improved by constructing edge-disjoint paths for each split multicast request. Moreover, in order to reduce the number of wavelengths required and further decrease the traffic blocking probability, a light-tree reconfiguration mechanism is presented in the MCSA-NC, which can select a minimal cost light tree from the established edge-disjoint paths for a new multicast request.

  5. 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.

  6. 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.

  7. Compensation of a distorted N-fold orbital angular momentum multicasting link using adaptive optics.

    PubMed

    Li, Shuhui; Wang, Jian

    2016-04-01

    By using an adaptive feedback correction technique, we experimentally demonstrate turbulence compensation for free-space four-fold and eight-fold 16-ary quadrature amplitude modulation (16-QAM) carrying orbital angular momentum (OAM) multicasting links. The performance of multicasted OAM beams through emulated atmospheric turbulence and adaptive optics assisted compensation loop is investigated. The experimental results show that the scheme can efficiently compensate for the atmospheric turbulence induced distortions, i.e., reducing power fluctuation of multicasted OAM channels, suppressing inter-channel crosstalk, and improving the bit-error rate (BER) performance. PMID:27192267

  8. On the Cost of Prioritized Atomic Multicast Protocols

    NASA Astrophysics Data System (ADS)

    Miedes, Emili; Muñoz-Escoí, Francesc D.

    A prioritized atomic multicast protocol allows an application to tag messages with a priority that expresses their urgency and tries to deliver first those with a higher priority. For instance, such a service can be used in a database replication context, to reduce the transaction abort rate when integrity constraints are used. We present a study of the three most important and well-known classes of atomic multicast protocols in which we evaluate the cost imposed by the prioritization mechanisms, in terms of additional latency overhead, computational cost and memory use. This study reveals that the behavior of the protocols depends on the particular properties of the setting (number of nodes, message sending rates, etc.) and that the extra work done by a prioritized protocol does not introduce any additional latency overhead in most of the evaluated settings. This study is also a performance comparison of these classes of total order protocols and can be used by system designers to choose the proper prioritized protocol for a given deployment.

  9. Abacus switch: a new scalable multicast ATM switch

    NASA Astrophysics Data System (ADS)

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

    1995-10-01

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

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Choi, Woo-Yong

    2011-11-01

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

  12. Avoiding congestion in recommender systems

    NASA Astrophysics Data System (ADS)

    Ren, Xiaolong; Lü, Linyuan; Liu, Runran; Zhang, Jianlin

    2014-06-01

    Recommender systems use the historical activities and personal profiles of users to uncover their preferences and recommend objects. Most of the previous methods are based on objects’ (and/or users’) similarity rather than on their difference. Such approaches are subject to a high risk of increasingly exposing users to a narrowing band of popular objects. As a result, a few objects may be recommended to an enormous number of users, resulting in the problem of recommendation congestion, which is to be avoided, especially when the recommended objects are limited resources. In order to quantitatively measure a recommendation algorithm's ability to avoid congestion, we proposed a new metric inspired by the Gini index, which is used to measure the inequality of the individual wealth distribution in an economy. Besides this, a new recommendation method called directed weighted conduction (DWC) was developed by considering the heat conduction process on a user-object bipartite network with different thermal conductivities. Experimental results obtained for three benchmark data sets showed that the DWC algorithm can effectively avoid system congestion, and greatly improve the novelty and diversity, while retaining relatively high accuracy, in comparison with the state-of-the-art methods.

  13. A one-shot access scheme for a multicast switch

    NASA Astrophysics Data System (ADS)

    Chen, Xing; Hayes, Jeremiah F.; Ali, M. K. Mehmet

    The capability of handling multipoint connections is essential for many communication needs. Input port queueing along with a contention resolution algorithm is used to resolve output request conflict. A study of the performance of a one-shot access scheme for a multicast packet switch is presented. The analysis is based on an assumption of random traffic, modeled by a Bernoulli process of packet arrival and Bernoulli trials of copy distribution patterns. Input port queueing along with random-selection policy is used to resolve the output request conflict. The primary performance measurement is the packet delay. A key assumption is that all copies of the same packet must be switched in the same slot. This one-shot discipline is easier to implement than one which disperses transmission over several time slots in small or medium size switching. Simulation results agree almost perfectly with the analysis.

  14. Reinforcement learning for congestion-avoidance in packet flow

    NASA Astrophysics Data System (ADS)

    Horiguchi, Tsuyoshi; Hayashi, Keisuke; Tretiakov, Alexei

    2005-04-01

    Occurrence of congestion of packet flow in computer networks is one of the unfavorable problems in packet communication and hence its avoidance should be investigated. We use a neural network model for packet routing control in a computer network proposed in a previous paper by Horiguchi and Ishioka (Physica A 297 (2001) 521). If we assume that the packets are not sent to nodes whose buffers are already full of packets, then we find that traffic congestion occurs when the number of packets in the computer network is larger than some critical value. In order to avoid the congestion, we introduce reinforcement learning for a control parameter in the neural network model. We find that the congestion is avoided by the reinforcement learning and at the same time we have good performance for the throughput. We investigate the packet flow on computer networks of various types of topology such as a regular network, a network with fractal structure, a small-world network, a scale-free network and so on.

  15. 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).

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

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

    PubMed

    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

  2. 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

  3. A novel optical path routing network that combines coarse granularity optical multicast with fine granularity add/drop and block

    NASA Astrophysics Data System (ADS)

    Soares, Mauro M.; Mori, Yojiro; Hasegawa, Hiroshi; Sato, Ken-ichi

    2015-01-01

    We propose a novel optical path routing mechanism that combines coarse-granularity optical multicast with fine-granularity add/drop and block. We implement the proposal in an optical cross-connect node with broadcast-and-select functionality that offers high cost-effectiveness since no addition equipment from conventional ROADMs is needed. The proposed method, called branching, enhances the routing capabilities over the original grouped routing networks by enabling wavelength paths to be established through different GRE pipes. We also present a novel path/GRE routing and wavelength/GRE index assignment algorithm that supports the new routing function. Numerical experiments using real network topologies verify the improved routing performance and the superior efficiency of the proposed control algorithm over original GRE-based networks.

  4. 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.

  5. Treatment of congestion in upper respiratory diseases

    PubMed Central

    Meltzer, Eli O; Caballero, Fernan; Fromer, Leonard M; Krouse, John H; Scadding, Glenis

    2010-01-01

    Congestion, as a symptom of upper respiratory tract diseases including seasonal and perennial allergic rhinitis, acute and chronic rhinosinusitis, and nasal polyposis, is principally caused by mucosal inflammation. Though effective pharmacotherapy options exist, no agent is universally efficacious; therapeutic decisions must account for individual patient preferences. Oral H1-antihistamines, though effective for the common symptoms of allergic rhinitis, have modest decongestant action, as do leukotriene receptor antagonists. Intranasal antihistamines appear to improve congestion better than oral forms. Topical decongestants reduce congestion associated with allergic rhinitis, but local adverse effects make them unsuitable for long-term use. Oral decongestants show some efficacy against congestion in allergic rhinitis and the common cold, and can be combined with oral antihistamines. Intranasal corticosteroids have broad anti-inflammatory activities, are the most potent long-term pharmacologic treatment of congestion associated with allergic rhinitis, and show some congestion relief in rhinosinusitis and nasal polyposis. Immunotherapy and surgery may be used in some cases refractory to pharmacotherapy. Steps in congestion management include (1) diagnosis of the cause(s), (2) patient education and monitoring, (3) avoidance of environmental triggers where possible, (4) pharmacotherapy, and (5) immunotherapy (for patients with allergic rhinitis) or surgery for patients whose condition is otherwise uncontrolled. PMID:20463825

  6. 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.

  7. 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.

  8. 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.

  9. Understanding congested travel in urban areas.

    PubMed

    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.

  10. 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

  11. Understanding congested travel in urban areas.

    PubMed

    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

  12. 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

  13. 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.

  14. 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

  15. A Secure Multicast Framework in Large and High-Mobility Network Groups

    NASA Astrophysics Data System (ADS)

    Lee, Jung-San; Chang, Chin-Chen

    With the widespread use of Internet applications such as Teleconference, Pay-TV, Collaborate tasks, and Message services, how to construct and distribute the group session key to all group members securely is becoming and more important. Instead of adopting the point-to-point packet delivery, these emerging applications are based upon the mechanism of multicast communication, which allows the group member to communicate with multi-party efficiently. There are two main issues in the mechanism of multicast communication: Key Distribution and Scalability. The first issue is how to distribute the group session key to all group members securely. The second one is how to maintain the high performance in large network groups. Group members in conventional multicast systems have to keep numerous secret keys in databases, which makes it very inconvenient for them. Furthermore, in case that a member joins or leaves the communication group, many involved participants have to change their own secret keys to preserve the forward secrecy and the backward secrecy. We consequently propose a novel version for providing secure multicast communication in large network groups. Our proposed framework not only preserves the forward secrecy and the backward secrecy but also possesses better performance than existing alternatives. Specifically, simulation results demonstrate that our scheme is suitable for high-mobility environments.

  16. Cell therapy in congestive heart failure*

    PubMed Central

    Tao, Ze-wei; Li, Long-gui

    2007-01-01

    Congestive heart failure (CHF) has emerged as a major worldwide epidemic and its main causes seem to be the aging of the population and the survival of patients with post-myocardial infarction. Cardiomyocyte dropout (necrosis and apoptosis) plays a critical role in the progress of CHF; thus treatment of CHF by exogenous cell implantation will be a promising medical approach. In the acute phase of cardiac damage cardiac stem cells (CSCs) within the heart divide symmetrically and/or asymmetrically in response to the change of heart homeostasis, and at the same time homing of bone marrow stem cells (BMCs) to injured area is thought to occur, which not only reconstitutes CSC population to normal levels but also repairs the heart by differentiation into cardiac tissue. So far, basic studies by using potential sources such as BMCs and CSCs to treat animal CHF have shown improved ventricular remodelling and heart function. Recently, however, a few of randomized, double-blind, placebo-controlled clinical trials demonstrated mixed results in heart failure with BMC therapy during acute myocardial infarction. PMID:17726746

  17. Role of Diuretics and Ultrafiltration in Congestive Heart Failure

    PubMed Central

    Shchekochikhin, Dmitry; Al Ammary, Fawaz; Lindenfeld, JoAnn; Schrier, Robert

    2013-01-01

    Volume overload in heart failure (HF) results from neurohumoral activation causing renal sodium and water retention secondary to arterial underfilling. Volume overload not only causes signs and symptoms of congestion, but can impact myocardial remodeling and HF progression. Thus, treating congestion is a cornerstone of HF management. Loop diuretics are the most commonly used drugs in this setting. However, up to 30% of the patients with decompensated HF present with loop-diuretic resistance. A universally accepted definition of loop diuretic resistance, however, is lacking. Several approaches to treat diuretic-resistant HF are available, including addition of distal acting thiazide diuretics, natriuretic doses of mineralocorticoid receptor antagonists (MRAs), or vasoactive drugs. Slow continuous veno-venous ultrafiltration is another option. Ultrafiltration, if it is started early in the course of HF decompensation, may result in prominent decongestion and a reduction in re-hospitalization. On the other hand, ultrafiltration in HF patients with worsening renal function and volume overload after aggressive treatment with loop diuretics, failed to show benefit compared to a stepwise pharmacological approach, including diuretics and vasoactive drugs. Early detection of congested HF patients for ultrafiltration treatment might improve decongestion and reduce readmission. However, the best patient characteristics and best timing of ultrafiltration requires further evaluation in randomized controlled studies. PMID:24276318

  18. Medical management of congestive heart failure in a horse.

    PubMed

    Brumbaugh, G W; Thomas, W P; Hodge, T G

    1982-04-15

    A 4-year-old Quarter Horse gelding with atrial fibrillation, mitral regurgitation, and signs of bilateral congestive heart failure was initially treated IV with digoxin and furosemide. After parenteral digitalization, a daily maintenance dose of digoxin was administered orally at a rate of 21.7 micrograms/kg of body weight. At this dosage, a steady-state serum digoxin concentration of 2.3 ng/ml was achieved without clinical signs of toxicosis. The furosemide dosage was decreased and eventually discontinued as clinical improvement occurred. Clinical signs of congestive heart failure were controlled and sinus rhythm was intermittently established, but an unfavorable prognosis was given for future athletic work. After 35 days of therapy, cardiac catheterization was performed and the horse was euthanatized. At necropsy there was marked dilatation of all cardiac chambers, mitral valve fibrosis, and left atrial jet lesions. The response of this patient suggested that orally administered digoxin may be useful in the management of congestive heart failure in selected equine patients.

  19. 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.

  20. 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

  1. 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. PMID:25993476

  2. 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.

  3. Using relaxational dynamics to reduce network congestion

    NASA Astrophysics Data System (ADS)

    Piontti, Ana L. Pastore y.; La Rocca, Cristian E.; Toroczkai, Zoltán; Braunstein, Lidia A.; Macri, Pablo A.; López, Eduardo

    2008-09-01

    We study the effects of relaxational dynamics on congestion pressure in scale-free (SF) networks by analyzing the properties of the corresponding gradient networks (Toroczkai and Bassler 2004 Nature 428 716). Using the Family model (Family and Bassler 1986 J. Phys. A: Math. Gen. 19 L441) from surface-growth physics as single-step load-balancing dynamics, we show that the congestion pressure considerably drops on SF networks when compared with the same dynamics on random graphs. This is due to a structural transition of the corresponding gradient network clusters, which self-organize so as to reduce the congestion pressure. This reduction is enhanced when lowering the value of the connectivity exponent λ towards 2.

  4. 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

  5. Congestive Heart Failure and Central Sleep Apnea.

    PubMed

    Sands, Scott A; Owens, Robert L

    2016-03-01

    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.

  6. 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.

  7. Analysis of Traffic Congestion by Considering Merging on Entry Lines in Transportation System

    NASA Astrophysics Data System (ADS)

    Hoshino, Takahiro; Tsuboi, Kazuhiro; Hamamatsu, Yoshio

    In a transportation system, a merging control strategy is necessary to avoid collisions between vehicles at a merging section with entry lines. In this study, under the assumption that each entry line is assigned time-independent priority, we analyze traffic congestion with a stochastic model. A quantitative estimation of the congestion is successfully obtained in terms of the average queue length and the average queuing delay. On the basis of analytical results, we propose a control strategy that changes the priority periodically. Using simulation, it is clarified that the proposed control strategy gives an arbitrary values of the queue length and the queuing delay on each line.

  8. Digoxin: A systematic review in atrial fibrillation, congestive heart failure and post myocardial infarction

    PubMed Central

    Virgadamo, Sebastiano; Charnigo, Richard; Darrat, Yousef; Morales, Gustavo; Elayi, Claude S

    2015-01-01

    AIM: To review digoxin use in systolic congestive heart failure, atrial fibrillation, and after myocardial infarction. METHODS: A comprehensive PubMed search was performed using the key words “digoxin and congestive heart failure”, “digoxin and atrial fibrillation”, “digoxin, atrial fibrillation and systolic congestive heart failure”, and “digoxin and myocardial infarction”. Only articles written in English were included in this study. We retained studies originating from randomized controlled trials, registries and included at least 500 patients. The studies included patients with atrial fibrillation or heart failure or myocardial infarction and had a significant proportion of patients (at least 5%) on digoxin. A table reviewing the different hazard ratios was developed based on the articles selected. Our primary endpoint was the overall mortality in the patients on digoxin vs those without digoxin, among patients with atrial fibrillation and also among patients with atrial fibrillation and systolic heart failure. We reviewed the most recent international guidelines to discuss current recommendations. RESULTS: A total of 18 studies were found that evaluated digoxin and overall mortality in different clinical settings including systolic congestive heart failure and normal sinus rhythm (n = 5), atrial fibrillation with and without systolic congestive heart failure (n = 9), and myocardial infarction (n = 4). Overall, patients with systolic congestive heart failure with normal sinus rhythm, digoxin appears to have a neutral effect on mortality especially if close digoxin level monitoring is employed. However, most of the observational studies evaluating digoxin use in atrial fibrillation without systolic congestive heart failure showed an increase in overall mortality when taking digoxin. In the studies evaluated in this systematic review, the data among patients with atrial fibrillation and systolic congestive heart failure, as well as post myocardial

  9. Context Aware Multiparty Session Support for Adaptive Multicasting in Heterogeneous Mobile Networks

    NASA Astrophysics Data System (ADS)

    Antoniou, Josephine; Riede, Christian; Pinto, Filipe Cabral; Pitsillides, Andreas

    The paper addresses the issue of achieving context-aware, adaptive multiparty sessions in a heterogeneous system by illustrating how to add elements of adaptivity and context-awareness to the session management functionality of such systems. The effective usage of situation/context information can lead to context-aware content casting, especially context-aware, adaptive multicasting. Therefore, regarding the multicast service, the key functionality of the enhanced session management is to create network subgroups based on network information as well as general user and environment context information to the extent that these are considered necessary for forming network-efficient groups, and in turn communicating the characteristics of these subgroups in the form of content stream descriptions to the media delivery function for obtaining the appropriate content for each subgroup.

  10. 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.

  11. Management and transmission of DICOM files using PC to PC multicasting methodology.

    PubMed

    Kim, I K; Kwon, G B; Choi, W K; Cho, H; Kwak, Y S

    2001-01-01

    The PACS system built and used in hospitals nowadays has quite significant overload on its central server because of both treatment of very large data and full management of medical images. We suggest a distributed communication and management methodology using PC to PC multicasting strategy for efficient management of medical images produced by DICOM modalities. It is absolutely necessary for reducing strict degradation of PACS system due to large size of medical images and its very high transport rates. DICOM PC to PC component is composed a service manager to execute requested queries, a communication manager to take charge of file transmission, and a DICOM manager to manage stored data and system behavior. Each manager itself is a component to search for requested file by interaction or transmit the file to other PCs. Distributed management and transformation of medical information based on PC to PC multicasting methodology will enhance performance of central server and network capacity reducing overload on them.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

    2013-08-01

    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. PMID:23747781

  19. 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.

  20. 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.

  1. Proceedings of the ITE's 1987 national conference on strategies to alleviate traffic congestion

    SciTech Connect

    Not Available

    1988-01-01

    These proceedings discuss the papers presented at the conference on the subject of traffic congestion. The topics discussed were: Surveillance control and driver information system; fiber optics for traffic surveillance; solutions to traffic problems; traffic management in Texas; truck operations; traffic engineering; parking standards and requirements; and planning of improving traffic flow on local streets.

  2. Containing air pollution and traffic congestion: Transport policy and the environment in Singapore

    NASA Astrophysics Data System (ADS)

    Chin, Anthony T. H.

    Land transportation remains one of the main contributors of noise and air pollution in urban areas. This is in addition to traffic congestion and accidents which result in the loss of productive activity. While there is a close relationship between traffic volumes and levels of noise and air pollution, transport authorities often assume that solving traffic congestion would reduce noise and air pollutant levels. Tight control over automobile ownership and use in Singapore has contributed in improving traffic flows, travel speeds and air quality. The adoption of internationally accepted standards on automobile emissions and gasoline have been effective in reducing air pollution from motor vehicles. Demand management measures have largely focused on controlling the source of traffic congestion, i.e. private automobile ownership and its use especially within the Central Business District during the day. This paper reviews and analyzes the effectiveness of two measures which are instrumental in controlling congestion and automobile ownership, i.e. road pricing and the vehicle quota scheme (VQS). While these measures have been successful in achieving desired objectives, it has also led to the spreading of traffic externalities to other roads in the network, loss in consumer welfare and rent seeking by automobile traders.

  3. 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.

  4. 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.

  5. New broadcasting protocols for video-on-demand systems in multicast environment

    NASA Astrophysics Data System (ADS)

    Feng, Jian; Poon, Wing-Fai; Lo, Kwok-Tung

    2002-09-01

    In this paper, two new broadcasting protocols are proposed for providing video-on-demand (VoD) services in multicast environment. The two protocols are developed by introducing a new first-segment delivery scheme for the skycraper and staggered protocols. With our approach, the first segment of a video is further divided into a number of small pieces so that customers can download the request data and start watching the video in a shorter time. The results show that the start-up latency for users is greatly reduced when using our new protocols.

  6. BlueGene/L Specific Modification to MRNet: Multicast/Reduction Network

    SciTech Connect

    Lee, G. L.; Ahn, D.

    2007-05-21

    MRNet is a software tree-based overlay network developed at the University of Wisconsin, Madison that provides a scalable communication mechanism for parallel tools. MRNet uses a tree topology of networked processes between a user tool and distributed tool daemons. This tree topology allows scalable multicast communication from the tool to the daemons. The internal nodes of the tree can be used to distribute computation and analysis on data sent from the tool daemons to the tool. This release covers modifications that we have made to the Wisconsin implementation to port this software to the BlueGene/L architecture. It also covers some additional files that were created for this port.

  7. A hybrid routing model for mitigating congestion in networks

    NASA Astrophysics Data System (ADS)

    He, Kun; Xu, Zhongzhi; Wang, Pu

    2015-08-01

    Imbalance between fast-growing transport demand and limited network supply has resulted in severe congestion in many transport networks. Increasing network supply or reducing transport demand could mitigate congestion, but these remedies are usually associated with high implementation cost. Combining shortest path (SP) routing and minimum cost (MC) routing, we developed a hybrid routing model to alleviate congestion in networks. This model requires only a small fraction of the total number of agents to use MC routes, and effectively mitigates congestion in networks under homogeneous or heterogeneous transport demand, offering new insights for improving the efficiency of practical transport networks.

  8. 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.

  9. 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%.

  10. Respiratory sleep disorders in patients with congestive heart failure

    PubMed Central

    2015-01-01

    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%. PMID:26380758

  11. Nutrient dyshomeostasis in congestive heart failure.

    PubMed

    Kamalov, German; Holewinski, Joshua P; Bhattacharya, Syamal K; Ahokas, Robert A; Sun, Yao; Gerling, Ivan C; Weber, Karl T

    2009-07-01

    The clinical syndrome congestive heart failure (CHF) has its origins rooted in a salt-avid state mediated largely by effector hormones of the renin-angiotensin-aldosterone system. In recent years, this cardiorenal perspective of CHF has taken on a broader perspective. One which focuses on a progressive systemic illness, whose major features include the presence of oxidative stress in diverse tissues and elevated circulating levels of proinflammatory cytokines coupled with a wasting of soft tissues and bone. Experimental studies, which simulate chronic renin-angiotensin-aldosterone system activation, and translational studies in patients with salt avidity having decompensated biventricular failure with hepatic and splanchnic congestion have forged a broader understanding of this illness and the important contribution of a dyshomeostasis of Ca2+, Mg2+, Zn2+, Se2+, and vitamins D, B12, and B1. Herein, we review biomarkers indicative of the nutrient imbalance found in CHF and raise the question of a need for a polynutrient supplement in the overall management of CHF. PMID:19593100

  12. 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

  13. 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.

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

    PubMed

    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

  15. 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.

  16. On the Relationship between Multicast/Broadcast Throughput and Resource Utilizations in Wireless Mesh Networks

    PubMed Central

    Valaee, Shahrokh

    2013-01-01

    This paper deals with the problem of multicast/broadcast throughput in multi-channel multi-radio wireless mesh networks that suffer from the resource constraints. We provide a formulation to capture the utilization of the network resources and derive analytical relationships for the network's throughput in terms of the node utilization, the channel utilization, and the number of transmissions. Our model relies on the on-demand quality of service multicast/broadcast sessions, where each admitted session creates a unique tree with a specific bandwidth. As an advantage, the derived relationships are independent of the type of tree built for each session and can be used for different protocols. The proposed formulation considers the channel assignment strategy and reflects both the wireless broadcast advantage and the interference constraint. We also offer a comprehensive discussion to evaluate the effects of load-balancing and number of transmissions on the network's throughput. Numerical results confirm the accuracy of the presented analysis. PMID:24348188

  17. Pulmonary congestion predicts cardiac events and mortality in ESRD.

    PubMed

    Zoccali, Carmine; Torino, Claudia; Tripepi, Rocco; Tripepi, Giovanni; D'Arrigo, Graziella; Postorino, Maurizio; Gargani, Luna; Sicari, Rosa; Picano, Eugenio; Mallamaci, Francesca

    2013-03-01

    Pulmonary congestion is highly prevalent and often asymptomatic among patients with ESRD treated with hemodialysis, but whether its presence predicts clinical outcomes is unknown. Here, we tested the prognostic value of extravascular lung water measured by a simple, well validated ultrasound B-lines score (BL-US) in a multicenter study that enrolled 392 hemodialysis patients. We detected moderate-to-severe lung congestion in 45% and very severe congestion in 14% of the patients. Among those patients with moderate-to-severe lung congestion, 71% were asymptomatic or presented slight symptoms of heart failure. Compared with those patients having mild or no congestion, patients with very severe congestion had a 4.2-fold risk of death (HR=4.20, 95% CI=2.45-7.23) and a 3.2-fold risk of cardiac events (HR=3.20, 95% CI=1.75-5.88) adjusted for NYHA class and other risk factors. Including the degree of pulmonary congestion in the model significantly improved the risk reclassification for cardiac events by 10% (P<0.015). In summary, lung ultrasound can detect asymptomatic pulmonary congestion in hemodialysis patients, and the resulting BL-US score is a strong, independent predictor of death and cardiac events in this population.

  18. Local debris congestion in the geosynchronous environment with population augmentation

    NASA Astrophysics Data System (ADS)

    Anderson, Paul V.; Schaub, Hanspeter

    2014-02-01

    Forecasting of localized debris congestion in the geostationary (GEO) regime is performed to investigate how frequently near-miss events occur for each of the longitude slots in the GEO ring. The present-day resident space object (RSO) population at GEO is propagated forward in time to determine current debris congestion conditions, and new probability density functions that describe where GEO satellites are inserted into operational orbits are harnessed to assess longitude-dependent congestion in "business-as-usual" launch traffic, with and without re-orbiting at end-of-life. Congestion forecasting for a 50-year period is presented to illustrate the need for appropriately executed mitigation measures in the GEO ring. Results indicate that localized debris congestion will double within 50 years under current 80% re-orbiting success rates.

  19. DEVICE CONTROLLER, CAMERA CONTROL

    1998-07-20

    This is a C++ application that is the server for the cameral control system. Devserv drives serial devices, such as cameras and videoswitchers used in a videoconference, upon request from a client such as the camxfgbfbx ccint program. cc Deverv listens on UPD ports for clients to make network contractions. After a client connects and sends a request to control a device (such as to pan,tilt, or zooma camera or do picture-in-picture with a videoswitcher),more » devserv formats the request into an RS232 message appropriate for the device and sends this message over the serial port to which the device is connected. Devserv then reads the reply from the device from the serial port to which the device is connected. Devserv then reads the reply from the device from the serial port and then formats and sends via multicast a status message. In addition, devserv periodically multicasts status or description messages so that all clients connected to the multicast channel know what devices are supported and their ranges of motion and the current position. The software design employs a class hierarchy such that an abstract base class for devices can be subclassed into classes for various device categories(e.g. sonyevid30, cononvco4, panasonicwjmx50, etc.). which are further subclassed into classes for various device categories. The devices currently supported are the Sony evi-D30, Canon, VCC1, Canon VCC3, and Canon VCC4 cameras and the Panasonic WJ-MX50 videoswitcher. However, developers can extend the class hierarchy to support other devices.« less

  20. DEVICE CONTROLLER, CAMERA CONTROL

    SciTech Connect

    Perry, Marcia

    1998-07-20

    This is a C++ application that is the server for the cameral control system. Devserv drives serial devices, such as cameras and videoswitchers used in a videoconference, upon request from a client such as the camxfgbfbx ccint program. cc Deverv listens on UPD ports for clients to make network contractions. After a client connects and sends a request to control a device (such as to pan,tilt, or zooma camera or do picture-in-picture with a videoswitcher), devserv formats the request into an RS232 message appropriate for the device and sends this message over the serial port to which the device is connected. Devserv then reads the reply from the device from the serial port to which the device is connected. Devserv then reads the reply from the device from the serial port and then formats and sends via multicast a status message. In addition, devserv periodically multicasts status or description messages so that all clients connected to the multicast channel know what devices are supported and their ranges of motion and the current position. The software design employs a class hierarchy such that an abstract base class for devices can be subclassed into classes for various device categories(e.g. sonyevid30, cononvco4, panasonicwjmx50, etc.). which are further subclassed into classes for various device categories. The devices currently supported are the Sony evi-D30, Canon, VCC1, Canon VCC3, and Canon VCC4 cameras and the Panasonic WJ-MX50 videoswitcher. However, developers can extend the class hierarchy to support other devices.

  1. 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

  2. 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.

  3. Cerebral blood flow in patients with congestive heart failure treated with captopril

    SciTech Connect

    Paulson, O.B.; Jarden, J.O.; Godtfredsen, J.; Vorstrup, S.

    1984-05-31

    The effect of captopril on cerebral blood flow was studied in five patients with severe congestive heart failure and in five control subjects. Cerebral blood flow was measured by inhalation of /sup 133/xenon and registration of its uptake and washout from the brain by single photon emission computer tomography. In addition, cerebral (internal jugular) venous oxygen tension was determined in the controls. The measurements were made before and 15, 60, and 180 minutes after a single oral dose of captopril (6.25 mg in patients with congestive heart failure and 25 mg in controls). Despite a marked decrease in blood pressure, cerebral blood flow increased slightly in the patients with severe congestive heart failure. When a correction was applied to take account of a change in arterial carbon dioxide tension, however, cerebral blood flow was unchanged after captopril administration even in patients with the greatest decrease in blood pressure, in whom a decrease in cerebral blood flow might have been expected. In the controls, blood pressure was little affected by captopril, whereas a slight, but not statistically significant, decrease in cerebral blood flow was observed. The cerebral venous oxygen tension decreased concomitantly.

  4. Local Debris Congestion in the Geosynchronous Environment with Population Augmentation

    NASA Astrophysics Data System (ADS)

    Anderson, P.; Schaub, H.

    2013-08-01

    Forecasting of localized debris congestion in the geostationary (GEO) ring is performed to investigate how frequently near-miss events occur for every longitude slot at GEO. A parallelized propagation routine is used to propagate the current resident space object (RSO) population at GEO forward in time, and representative augmentation of this population is implemented to simulate congestion in "business-as-usual" launch traffic, with and without mitigation at end-of-life. Congestion forecasting for a 50- year time frame is presented to illustrate the need for both appropriately-executed mitigation and active remediation measures at GEO.

  5. Dissemination of information in complex networks with congestion

    NASA Astrophysics Data System (ADS)

    Cholvi, Vicent

    2006-07-01

    We address the problem of message transfer in complex networks with congestion. We propose a new strategy aimed at improving routing efficiency. Such a strategy, contrary to the shortest available path length from a given source to its destination (perhaps the most widely analyzed routing strategy), takes into account the congestion of nodes and can be deployed, with a minimal overhead, on top of it. Our results show that, by distributing more homogeneously the congestion of nodes, it significantly reduces the average network load as well as the collapse point.

  6. BlueGene/L Specific Modification to MRNet: Multicast/Reduction Network

    2007-05-21

    MRNet is a software tree-based overlay network developed at the University of Wisconsin, Madison that provides a scalable communication mechanism for parallel tools. MRNet uses a tree topology of networked processes between a user tool and distributed tool daemons. This tree topology allows scalable multicast communication from the tool to the daemons. The internal nodes of the tree can be used to distribute computation and analysis on data sent from the tool daemons to themore » tool. This release covers modifications that we have made to the Wisconsin implementation to port this software to the BlueGene/L architecture. It also covers some additional files that were created for this port.« less

  7. 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.

  8. Performance comparison of two input access methods for a multicast switch

    NASA Astrophysics Data System (ADS)

    Chen, Xing; Hayes, Jeremiah F.; Mehmet-Ali, Mustafa K.

    1994-05-01

    A comparison of the performance of two input access mechanisms for multicast switching is presented. The first of these - A cyclic priority input access method - is a derivative of the ring token reservation method which eliminates the unfairness of the ordinary ring token reservation. It has the advantage of being relatively simple and easy to implement. A second approach employs a neural network to resolve output port conflict. While more difficult to implement, it has a delay-throughput performance advantage over the cyclic priority approach. The primary performance measurements are the switch throughput and the packet delay. A key assumption is that all copies of the same packet must be switched in the same slot.

  9. 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.

  10. 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.

  11. Agile multicasting based on cascaded χ(2) nonlinearities in a step-chirped periodically poled lithium niobate.

    PubMed

    Ahlawat, Meenu; Bostani, Ameneh; Tehranchi, Amirhossein; Kashyap, Raman

    2013-08-01

    We experimentally demonstrate the possibility of agile multicasting for wavelength division multiplexing (WDM) networks, of a single-channel to two and seven channels over the C band, also extendable to S and L bands. This is based on cascaded χ(2) nonlinear mixing processes, namely, second-harmonic generation (SHG)-sum-frequency generation (SFG) and difference-frequency generation (DFG) in a 20-mm-long step-chirped periodically poled lithium niobate crystal, specially designed and fabricated for a 28-nm-wide SH-SF bandwidth centered at around 1.55 μm. The multiple idlers are simultaneously tuned by detuning the pump wavelengths within the broad SH-SF bandwidth. By selectively tuning the pump wavelengths over less than 10 and 6 nm, respectively, multicasting into two and seven idlers is successfully achieved across ~70 WDM channels within the 50 GHz International Telecommunication Union grid spacing.

  12. 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.

  13. 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.

  14. 75 FR 22770 - National Electric Transmission Congestion Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... is seeking comments on all aspects of the study. The full text of the 2009 Congestion Study is... in each area.\\2\\ \\1\\ See 71 FR 45047 (August 6, 2006). \\2\\ See 72 FR 56992 (October 5, 2007)....

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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. PMID:7522455

  3. Performance Analysis of Multicast Video Streaming in IEEE 802.11 b/g/n Testbed Environment

    NASA Astrophysics Data System (ADS)

    Kostuch, Aleksander; Gierłowski, Krzysztof; Wozniak, Jozef

    The aim of the work is to analyse capabilities and limitations of different IEEE 802.11 technologies (IEEE 802.11 b/g/n), utilized for both multicast and unicast video streaming transmissions directed to mobile devices. Our preliminary research showed that results obtained with currently popular simulation tools can be drastically different than these possible in real-world environment, so, in order to correctly evaluate performance of video streaming, a simple wireless test-bed infrastructure has been created. The results show a strong dependence of the quality of video streaming on the chosen transmission technology. At the same time there are significant differences in perception quality between multicast (1:n) and unicast (1:1) streams, and also between devices offered by different manufacturers. The overall results seem to demonstrate, that, while multicast support quality in different products is still varied and often requires additional configuration, it is possible to select a WiFi access point model and determine the best system parameters to ensure a good video transfer conditions in terms of acceptable QoP/E (Quality of Perception/Exellence).

  4. A Multi-core Shared Tree Algorithm Based on Network Coding for Multi-point Optical Multicast

    NASA Astrophysics Data System (ADS)

    Liu, Huanlin; Yang, Yuming; Li, Yuan; Chen, Yong; Huang, Sheng

    2015-03-01

    With the growth of multi-point to multi-point multicast applications, the optical network bandwidth resource consumption is increasing rapidly. It attracted more and more researchers to improve the limited wavelength bandwidth utilization for multicast applications in wavelength division multiplexing (WDM) networks. In the paper, a multi-core shared multicast tree algorithm based on network coding is proposed to minimize the fiber link stress. The proposed algorithm includes three processes: searching the core node candidate set excluding core node loop path, selecting the core nodes from the convergence matrix based on heuristic algorithm, and constructing the multi-core nodes shared trees. The convergence matrix based on the heuristic method is constructed for selecting the core nodes from candidate core node set. To improve the limited wavelength utilization, we introduce network coding into the shared tree to compress the transmitting information. The simulation results show that the proposed algorithm's performance is better than the existing algorithms' performance in terms of link stress and balance degree.

  5. CONGESTIVE HEART FAILURE: WHERE HOMEOSTASIS BEGETS DYSHOMEOSTASIS

    PubMed Central

    Kamalov, German; Bhattacharya, Syamal K.; Weber, Karl T.

    2010-01-01

    Despite today’s standard of care, aimed at containing homeostatic neurohormonal activation, 1 in every 5 patients recently hospitalized with congestive heart failure (CHF) will be readmitted within 30 days of discharge because of a recurrence of their symptoms and signs. In light of recent pathophysiologic insights, it is now propitious to revisit CHF with a view toward complementary and evolving management strategies. CHF is a progressive systemic illness. Its features include: oxidative stress in diverse tissues; an immunostimulatory state with circulating proinflammatory cytokines; a wasting of soft tissues; and a resorption of bone. Its origins are rooted in homeostatic mechanisms gone awry to beget dyshomeostasis. For example, marked excretory losses of Ca2+ and Mg2+ accompany renin-angiotensin-aldosterone system (RAAS) activation, causing ionized hypocalcemia and hypomagnesemia that lead to secondary hyperparathyroidism (SHPT) with consequent bone resorption and a propensity to atraumatic fractures. Parathyroid hormone (PTH) accounts for paradoxical intracellular Ca2+ overloading in diverse tissues and consequent systemic induction of oxidative stress. In cardiac myocytes and mitochondria these events orchestrate opening of the mitochondrial membrane permeability transition pore (mPTP) with an ensuing osmotic-based destruction of these organelles and resultant cardiomyocyte necrosis with myocardial scarring. Contemporaneous with Ca2+ and Mg2+ dyshomeostasis is hypozincemia and hyposelenemia, which compromise metalloenzyme-based antioxidant defenses while hypovitaminosis D threatens Ca2+ stores needed to prevent SHPT. An intrinsically coupled dyshomeostasis of intracellular Ca2+ and Zn2+, representing prooxidant and antioxidant, respectively, is integral to regulating mitochondrial redox state; it can be uncoupled by a Zn2+ supplement in favor of antioxidant defenses. Hence, the complementary use of nutriceuticals to nullify dyshomeostatic responses

  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. PMID:27334011

  7. 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.

  8. 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.

  9. 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. PMID:26960217

  10. Quality of congestive heart failure care

    PubMed Central

    Maddocks, Heather; Marshall, J. Neil; Stewart, Moira; Terry, Amanda L.; Cejic, Sonny; Hammond, Jo-Anne; Jordan, John; Chevendra, Vijaya; Denomme, Louisa Bestard; Thind, Amardeep

    2010-01-01

    ABSTRACT OBJECTIVE To study the feasibility of using electronic medical record (EMR) data from the Deliver Primary Healthcare Information (DELPHI) database to measure quality of care for patients with congestive heart failure (CHF) in primary care and to determine the percentage of patients with CHF receiving the recommended care. DESIGN Items listed on the Ontario Ministry of Health and Long-Term Care Heart Failure Patient Care Flow Sheet (CHF flow sheet) were assessed and measured using EMRs of patients diagnosed with CHF between October 1, 2005, and September 30, 2008. SETTING Ten primary health care practices in southwestern Ontario. PARTICIPANTS Four hundred eighty-eight patients who were considered to have CHF because at least 1 of the following was indicated in their EMRs: an International Classification of Diseases billing code for CHF (category 428), an International Classification of Primary Care diagnosis code for heart failure (ie, K77), or “CHF” reported on the problem list. MAIN OUTCOME MEASURES Number of CHF flow sheet items that were measurable using EMR data from the DELPHI database. Percentage of patients with CHF receiving required quality-of-care items since the date of diagnosis. RESULTS The DELPHI database contained information on 60 (65.9%) of the 91 items identified using the CHF flow sheet. The recommended tests and procedures were recorded infrequently: 55.5% of patients with CHF had chest radiographs; 32.6% had electrocardiograms; 32.2% had echocardiograms; 30.5% were prescribed angiotensin-converting enzyme inhibitors; 20.9% were prescribed β-blockers; and 15.8% were prescribed angiotensin II receptor blockers. CONCLUSION Low frequencies of recommended care items for patients with CHF were recorded in the EMR. Physicians explained that CHF care was documented in areas of the EMR that contained patient identifiers, such as the encounter notes, and was therefore not part of the DELPHI database. Extractable information from the EMR

  11. 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

  12. 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

  13. All-Optical 1-to-8 Wavelength Multicasting at 20 Gbit/s Exploiting Self-Phase Modulation in Dispersion Flattened Highly Nonlinear Photonic Crystal Fiber

    PubMed Central

    Hui, Zhan-Qiang

    2014-01-01

    All-optical multicasting of performing data routing from single node to multiple destinations in the optical domain is promising for next generation ultrahigh-peed photonic networks. Based on the self-phase modulation in dispersion flattened highly nonlinear photonic crystal fiber and followed spectral filtering, simultaneous 1-to-8 all-optical wavelength multicasting return-to-zero (RZ) signal at 20 Gbit/s with 100 GHz channel spaced is achieved. Wavelength tunable range and dynamic characteristic of proposed wavelength multicasting scheme is further investigated. The results show our designed scheme achieve operation wavelength range of 25 nm, OSNR of 32.01 dB and Q factor of 12.8. Moreover, the scheme has simple structure as well as high tolerance to signal power fluctuation. PMID:24711738

  14. Research on Urban Road Traffic Congestion Charging Based on Sustainable Development

    NASA Astrophysics Data System (ADS)

    Ye, Sun

    Traffic congestion is a major problem which bothers our urban traffic sustainable development at present. Congestion charging is an effective measure to alleviate urban traffic congestion. The paper first probes into several key issues such as the goal, the pricing, the scope, the method and the redistribution of congestion charging from theoretical angle. Then it introduces congestion charging practice in Singapore and London and draws conclusion and suggestion that traffic congestion charging should take scientific plan, support of public, public transportation development as the premise.

  15. 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.

  16. 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.

  17. 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.

  18. 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).

  19. Gene transfer for congestive heart failure: update 2013.

    PubMed

    Tang, Tong; Hammond, H Kirk

    2013-04-01

    Congestive heart failure is a major cause of morbidity and mortality with increasing social and economic costs. There have been no new high impact therapeutic agents for this devastating disease for more than a decade. However, many pivotal regulators of cardiac function have been identified using cardiac-directed transgene expression and gene deletion in preclinical studies. Some of these increase function of the failing heart. Altering the expression of these pivotal regulators using gene transfer is now either being tested in clinical gene transfer trials, or soon will be. In this review, we summarize recent progress in cardiac gene transfer for clinical congestive heart failure.

  20. Congestion estimation technique in the optical network unit registration process.

    PubMed

    Kim, Geunyong; Yoo, Hark; Lee, Dongsoo; Kim, Youngsun; Lim, Hyuk

    2016-07-01

    We present a congestion estimation technique (CET) to estimate the optical network unit (ONU) registration success ratio for the ONU registration process in passive optical networks. An optical line terminal (OLT) estimates the number of collided ONUs via the proposed scheme during the serial number state. The OLT can obtain congestion level among ONUs to be registered such that this information may be exploited to change the size of a quiet window to decrease the collision probability. We verified the efficiency of the proposed method through simulation and experimental results.

  1. 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

  2. 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. PMID:27526048

  3. Increased Rho kinase activity in congestive heart failure

    PubMed Central

    Dong, Ming; Liao, James K.; Fang, Fang; Lee, Alex Pui-Wai; Yan, Bryan Ping-Yen; Liu, Ming; Yu, Cheuk-Man

    2012-01-01

    Aims Rho kinases (ROCKs) are the best characterized effectors of the small G-protein RhoA, and play a role in enhanced vasoconstriction in animal models of congestive heart failure (CHF). This study examined if ROCK activity is increased in CHF and how it is associated with the outcome in CHF. Methods and results Patients admitted with CHF (n =178), disease controls (n =31), and normal subjects (n =30) were studied. Baseline ROCK activity was measured by phosphorylation of themyosin-binding subunit in peripheral leucocytes. The patients were followed up for 14.4 ± 7.2 months (range 0.5–26 months) or until the occurrence of cardiac death. The ROCK activity in CHF patients (2.93 ± 0.87) was significantly higher than that of the disease control (2.06 ± 0.38, P < 0.001) and normal control (1.57 ± 0.43, P < 0.001) groups. Similarly, protein levels of ROCK1 and ROCK2 as well as the activity of RhoA in CHF were significantly higher than in disease controls and normal controls (all P < 0.05). Dyspnoea at rest (β =0.338, P < 0.001), low left ventricular ejection fraction (β = –0.277, P < 0.001), and high creatinine (β =0.202, P =0.006) were independent predictors of the baseline ROCK activity in CHF. Forty-five patients died within 2 years follow-up (25.3%). Combining ROCK activity and N-terminal pro brain natriuretic peptide (NT-proBNP) had an incremental value (log rank χ2 =11.62) in predicting long-term mortality when compared with only NT-proBNP (log rank χ2 =5.16, P < 0.05). Conclusion ROCK activity is increased in CHF and it might be associated with the mortality in CHF. ROCK activity might be a complementary biomarker to CHF risk stratification. PMID:22588320

  4. 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

  5. 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. PMID:26185181

  6. 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)

  7. Nuclear angiography in a dog with congestive cardiomyopathy

    SciTech Connect

    Lippert, A.C.; Twardock, A.R.; Gelberg, H.B.

    1986-03-01

    Nuclear angiography was used as a diagnostic aid and in monitoring the clinical course of a case of congestive cardiomyopathy in a dog. Serial examinations revealed progressively deteriorating values for left ventricular ejection fraction before the dog's death. This noninvasive technique can be an alternative to echocardiography for the evaluation of cardiac performance.

  8. Intramembrane congestion effects on lysenin channel voltage-induced gating

    PubMed Central

    Krueger, Eric; Bryant, Sheenah; Shrestha, Nisha; Clark, Tyler; Hanna, Charles; Pink, David; Fologea, Daniel

    2016-01-01

    All cell membranes are packed with proteins. The ability to investigate the regulatory mechanisms of protein channels in experimental conditions mimicking their congested native environment is crucial for understanding the environmental physicochemical cues that may fundamentally contribute to their functionality in natural membranes. Here we report on investigations of the voltage-induced gating of lysenin channels in congested conditions experimentally achieved by increasing the number of channels inserted into planar lipid membranes. Typical electrophysiology measurements reveal congestion-induced changes to the voltage-induced gating, manifested as a significant reduction of the response to external voltage stimuli. Furthermore, we demonstrate a similar diminished voltage sensitivity for smaller populations of channels by reducing the amount of sphingomyelin in the membrane. Given lysenin’s preference for targeting lipid rafts, this result indicates the potential role of the heterogeneous organization of the membrane in modulating channel functionality. Our work indicates that local congestion within membranes may alter the energy landscape and the kinetics of conformational changes of lysenin channels in response to voltage stimuli. This level of understanding may be extended to better characterize the role of the specific membrane environment in modulating the biological functionality of protein channels in health and disease. PMID:26695013

  9. 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.

  10. 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.

  11. 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...

  12. 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...

  13. TCP with source traffic shaping (TCP-STS): an approach for network congestion reduction

    NASA Astrophysics Data System (ADS)

    Elaywe, Ali H.; Kamal, Ahmed E.

    2002-07-01

    The Transmission Control Protocol (TCP), provides flow control functions which are based on the window mechanism. Packet losses are detected by various mechanisms, such as timeouts and duplicate acknowledgements, and are then recovered from using different techniques. A problem that arises with the use of window based mechanisms is that the availability of a large number of credits at the source may cause a source to flood the network with back-to-back packets, which may drive the network into congestion, especially if multiple sources become active at the same time. In this paper we propose a new approach for congestion reduction. The approach works by shaping the traffic at the TCP source, such that the basic TCP flow control mechanism is still preserved, but the packet transmissions are spaced in time in order to prevent a sudden surge of traffic from overflowing the routers' buffers. Simulation results show that this technique can result in an improved network performance, in terms of reduced mean delay, delay variance, and packet dropping ratio.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Louf, Rémi; Barthelemy, Marc

    2014-07-01

    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.

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

    PubMed

    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.

  17. D-ribose, a metabolic substrate for congestive heart failure.

    PubMed

    Wagner, Susan; Herrick, James; Shecterle, Linda M; St Cyr, John A

    2009-06-01

    The incidence of congestive heart failure continues to escalate worldwide, taxing health care systems. Current therapies focus on clinical management. Current accepted regimens have provided some success; however, most patients show progression of their disease. Because of this failure, research continues to explore therapies directed at stabilization of their disease and hopefully to improve the downward spiral. Publications have asserted that the failing heart is energy starved. D-ribose, a naturally occurring pentose carbohydrate and a key component in the adenosine triphosphate (ATP) molecule, has demonstrated an ability to replenish ATP levels and improve diastolic dysfunction following myocardial ischemia, which has been shown to improve the clinical state of patients afflicted with congestive heart failure. D-ribose may provide the necessary metabolic substrate to benefit this energy-deficient state found in heart failure. PMID:19523159

  18. Evolution of the chronic congestive heart failure paradigm.

    PubMed

    Savino, John A; Kosmas, Constantine E; Wagman, Gabriel; Vittorio, Timothy J

    2013-01-01

    Paradigms are a part of our human nature. In the world of medicine and science, they allow investigators to work within a particular, previously accepted framework that provides certain constraints. This is the crux of Newton's quote, "If I've seen so far it's because I stood upon the shoulders of giants." However, in the same way that it allows us to build, it can constrain our thought processes if we fail to accept new data that are ill suited to an accepted paradigm. The physiological mechanisms to explain the phenomenon of chronic congestive heart failure are similar to other paradigms of science, in that they have undergone several shifts throughout their history, and continue to change with new evidence. Here, we seek to explore how our understanding of congestive heart failure has changed.

  19. The case for treating refractory congestive heart failure with ultrafiltration.

    PubMed

    Canaud, Bernard; Bowry, Sudhir K; Tetta, Ciro; Gatti, Emanuele

    2014-01-01

    Extracellular fluid retention and congestion is a fundamental manifestation of heart failure (HF) and cardiorenal syndrome (CRS). Patients are normally hospitalized and treated with diuretics, but their outcomes are often poor as severe congestion and diuretics resistance is the primary cause of HF-related hospital admissions and readmissions. Isolated ultrafiltration (UF), which can be considered as a 'mechanical diuretic and natriuretic' tool, offers promise in achieving safe and effective fluid volume removal in HF patients with CRS who are resistant to stepwise guided diuretic therapy. This paper outlines the rationale for machine-driven isolated UF in CRS and the available clinical evidence regarding its use in patients with HF. In addition, this article summarizes some future clinical perspectives for expanding the use of UF therapy in HF patients in order to improve outcomes. PMID:25196568

  20. Decreased renal clearance of digoxin in chronic congestive heart failure.

    PubMed

    Naafs, M A; van der Hoek, C; van Duin, S; Koorevaar, G; Schopman, W; Silberbusch, J

    1985-01-01

    Renal digoxin clearance was compared in patients suffering from atrial fibrillation with well preserved cardiac function (n = 9; salt intake +/- 170 mmol daily) and patients with chronic congestive heart failure (n = 10; salt intake 50 mmol daily and maintenance treatment with diuretics). There was no difference between the groups concerning digoxin dosage, creatinine clearance, diuresis or sodium excretion in the urine. Digoxin clearance in chronic heart failure proved to be significantly lower than in atrial fibrillation (48 +/- 21 vs 71 +/- 36 ml X min-1, p less than 0.05), and Cdig/Ccreat was similarly reduced at 0.73 +/- 0.15 compared to 1.09 +/- 0.27 (p less than 0.005). Steady state serum digoxin concentration was significantly higher in patients with congestive heart failure (1.44 +/- 0.47 vs 0.87 +/- 0.33 micrograms X 1(-1), p less than 0.01). Chronic congestive heart failure is a state with reduced digoxin clearance by the kidney, which could lead to digoxin intoxication not explicable by overdose, reduced renal function or the effect of interacting drugs. PMID:4007028

  1. 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

  2. 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

  3. 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.

  4. Congestive heart failure in acromegaly: A review of 6 cases

    PubMed Central

    Dutta, P.; Das, S.; Bhansali, A.; Bhadada, S. K.; Rajesh, B. V.; Reddy, K. S.; Vaiphei, K.; Mukherjee, K. K.; Pathak, A.; Shah, V. N.

    2012-01-01

    Background: Though cardiac involvement is common in acromegaly, overt congestive heart failure is uncommon. Materials and Methods: This is retrospective analysis of hospital record between 1996 and 2007. We analyzed records of 150 consecutive patients with acromegaly. We included the patients with acromegaly those who had overt congestive heart failure either at presentation or during the course of illness for the present analysis. The diagnosis of acromegaly and congestive cardiac failure were based on standard criteria. Results: Out of 150 patients with acromegaly, 6 patients had overt CHF (4.0%), of which 4 presented with the features of CHF and 2 developed during the course of illness. Three patients had hypertension and 1 had diabetes. Baseline echocardiography showed severe biventricular dysfunction and global hypokinesia in all. Angiography showed dilated hypokinetic left ventricle with normal coronaries in 3, it was confirmed at autopsy in 1. Three underwent trans-sphenoidal surgery, 1 received somatostatin analogue as primary treatment modality. Normalization of growth hormone and IGF-1 led to improvement in cardiac function in 1, 1 patient lost to follow up, and 4 died during the course of illness. In 1 patient, autopsy was performed and cardiac specimen revealed normal coronaries, concentric ventricular hypertrophy, and dilatation with myofibrolysis and interfascicular fibrosis. Conclusion: Prevalence of overt CHF is 4% in present series. Overt CHF carries poor prognosis and hence, this complication should be recognized at earliest, and medical management to normalized cardiac function should be given utmost priority. PMID:23226648

  5. 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

    2016-01-01

    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

  6. 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. PMID:25849534

  7. Dynamically-induced structures formation in congested magma

    NASA Astrophysics Data System (ADS)

    Petford, N.

    2008-12-01

    Crystal fabrics preserved in igneous rocks offer a glimpse into the magma emplacement process. Detailed field mapping, in combination with AMS studies, seem to provide the best available data for unravelling intrusion architecture on the decimetre scale. However, a full and proper understanding of the fluid dynamics of congested fluid-particle mixtures during shear remains elusive. This is a shame as without recourse to such fundamental understanding, the interpretation of structural field data in the context of magma flow remains problematic. One way to gain insight into the process is to treat flowing magma as a dynamic material with a rheology similar to sheared, congested slurries. The fancy that dense magma equates to a high temperature slurry is an attractive one, and opens up a way to examine the emplacement process that does not rely exclusively on equilibrium thermodynamics as a final explanation of commonly observed igneous structures. Instead, using examples from mafic rocks where cooling has been rapid, the idea is put forward that in high Peclet number suspensions (where particle diffusion is negligible), shearing and non- Newtonian behaviour imparts a rich diversity of structures including layering, grading and flow segregation. Key to understanding the rheology, hence flow dynamics of congested magma, is the particle microstructure, a still poorly known essence of suspension flows. Where magma transport is continental in scale and long lived (e.g. Large Igneous Provinces), rotation of the earth may in theory endow a small but potentially measurable imprint on the preserved flow fabric.

  8. End-to-End Flow Control Using PI Controller for Servo Control over Networks

    NASA Astrophysics Data System (ADS)

    Yashiro, Daisuke; Kubo, Ryogo; Yakoh, Takahiro; Ohnishi, Kouhei

    This paper presents a novel flow control method using a PI controller for servo control over networks. The UDP is known to be effective for motion control systems over networks such as bilateral teleoperation. However, UDP does not have a mechanism for congestion avoidance. The congestion, which causes large communication delay, jitter, and packet loss, deteriorates the performance and stability of control systems over networks. To avoid this congestion, a novel flow control method, which adjusts a packet-sending period in real time, is proposed. The validity of the proposed method is shown by simulation and experimental results.

  9. 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.

  10. 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. PMID:26721569

  11. Factors contributing to the hospitalization of patients with congestive heart failure.

    PubMed Central

    Chin, M H; Goldman, L

    1997-01-01

    OBJECTIVES: This study identifies acute precipitants of hospitalization and evaluates utilization of angiotension-converting enzyme inhibitors in patients admitted with congestive heart failure. METHODS: Cross-sectional chart-review study was done of 435 patients admitted nonelectively from February 1993 to February 1994 to an urban university hospital with a complaint of shortness of breath or fatigue and evidence of congestive heart failure. RESULTS: The most common identifiable abnormalities associated with clinical deterioration prior to admission were acute anginal chest pain (33%), respiratory infection (16%), uncontrolled hypertension with initial systolic blood pressure > or = 180 mm Hg (15%), atrial arrhythmia with heart rate > or = 120 (8%), and noncompliance with medications (15%) or diet (6%); in 34% of patients, no clear cause could be identified. After exclusion of those who were already on a different vasodilator or who had relative contraindications, 18 (32%) of the patients with ejection fractions < or = 0.35 measured prior to admission were not taking an angiotensin-converting enzyme inhibitor on presentation to the hospital. CONCLUSIONS: Interventions to improve compliance, the control of hypertension, and the appropriate use of angiotensin-converting enzyme inhibitors may prevent many hospitalizations of heart-failure patients. PMID:9146445

  12. 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

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

    PubMed

    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%.

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

    PubMed

    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

  15. 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

  16. 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.

  17. 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

  18. 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

  19. Team management of congestive heart failure across the continuum.

    PubMed

    Venner, G H; Seelbinder, J S

    1996-01-01

    Despite an increased incidence of congestive heart failure and frequency of hospital admissions for the Medicare population, there is little information available on improving outcomes for these patients. As changes in health care lead toward capitation, efficient care with limited use of expensive inpatient hospital resources is a necessity. The coordination of three critical components--inpatient, outpatient, and home care--can lead to positive outcomes in terms of functional capacity changes, length of stay, readmission rates, patient self-care knowledge, and patient satisfaction.

  20. [Gliptins, cardiovascular safety and congestive heart failure: state of the art after TECOS].

    PubMed

    Scheen, A J

    2015-08-26

    The cardiovascular safety of dipeptidyl peptidase-4 inhibitors (gliptins) has been well studied. Favourable effects of these oral antidiabetic agents have been reported in meta-analyses of phase II-III randomised controlled trials. Three large prospective trials, which were specifically designed to investigate cardiovascular safety, showed non-inferiority of saxagliptin (SAVOR-TIMI 53), alogliptin (EXA-MINE) and sitagliptin (TECOS) versus placebo as far as major cardiovascular events are concerned, including mortality. The suspected increase in the rate of hospitalisation due to congestive heart failure reported in SAVOR-TIMI 53 was neither found in EXAMINE nor recently confirmed in TECOS. Direct comparative trials, evaluating not only safety but also efficacy, with other oral antidiabetic medications would be of major interest.

  1. Essay in the theory of uncontrolled flows and congestion

    SciTech Connect

    Iri, M.

    1994-12-31

    A new type of network flow theory is proposed, where only those flows which are representable as a positive sum of elementary-path (or elementary-cycle) flows are considered and no cancellation of flows in an edge is admitted when two or more flows are superposed. It offers a general framework in which to discuss about congestion, blocking flows, etc. in a network. We will call the flows in this framework {open_quotes}uncontrollable flows{close_quotes} because they possess some basic properties of the flows which selfish and stubborn users, or users in emergency situations, generate in a network. Primarily, this is not a mathematics paper but one to introduce a new viewpoint from which to give another look at network flow problems. However, a number of interesting mathematical problems naturally arise in so doing: e.g., {open_quotes}Is a given flow uncontrollable{close_quotes}?, {open_quotes}How to determine a blocking flow or a bottleneck cut{close_quotes}?, {open_quotes}Can we design a network in which no congestion may occur{close_quotes}?, {open_quotes}Under what conditions does additional investment on a network improve its function in this framework{close_quotes}?, etc. What kind of practical problems will be the dual of the concept of uncontrollable flows will also be discussed.

  2. Congestion phenomena caused by matching pennies in evolutionary games.

    PubMed

    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. PMID:25871057

  3. Predicting travel time to limit congestion at a highway bottleneck

    NASA Astrophysics Data System (ADS)

    Davis, L. C.

    2010-09-01

    A new method is proposed to predict the travel time on a highway route with a bottleneck caused by an on-ramp. The method takes advantage of the slow variation of the bottleneck throughput when congestion exists. The predicted travel time for a vehicle leaving the origin is given by the current number of vehicles on the route divided by the estimated throughput. The latter is an average of N/T recorded as each vehicle reaches the destination where N is the number of vehicles at the start of the trip and T is the time to complete the trip. Drivers divert to an off-ramp when the predicted travel time exceeds a target value. The target could be historical average travel times of alternative routes or chosen to limit the amount of congestion. Simulations employing three-phase traffic theory show that the travel time converges to the target value and remains close to or below it with the proposed prediction strategy. Strong oscillations in travel time obtained when other strategies are used for diversion do not develop with the new method because the inherent delay is effectively removed.

  4. Congestion phenomena caused by matching pennies in evolutionary games.

    PubMed

    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.

  5. 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.

  6. 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.

  7. Quasi-static evolution and congested crowd transport

    NASA Astrophysics Data System (ADS)

    Alexander, Damon; Kim, Inwon; Yao, Yao

    2014-04-01

    We consider the relationship between Hele-Shaw evolution with drift, the porous medium equation with drift, and a congested crowd motion model originally proposed by Maury et al (2010 Math. Models Methods Appl. Sci. 20 1787-821). We first use viscosity solutions to show that the porous medium equation solutions converge to the Hele-Shaw solution as m → ∞ provided the drift potential is strictly subharmonic. Next, using the gradient-flow structure of both the porous medium equation and the crowd motion model, we prove that the porous medium equation solutions also converge to the congested crowd motion as m → ∞. Combining these results lets us deduce that in the case where the initial data to the crowd motion model is given by a patch, or characteristic function, the solution evolves as a patch that is the unique solution to the Hele-Shaw problem. While proving our main results we also obtain a comparison principle for solutions with the minimizing movement scheme based on the Wasserstein metric, of independent interest.

  8. 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

  9. 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

  10. 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... 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...

  11. Evaluation of performance characteristics of the medicinal leech (Hirudo medicinalis) for the treatment of venous congestion.

    PubMed

    Conforti, Michael L; Connor, Nadine P; Heisey, Dennis M; Hartig, Gregory K

    2002-01-01

    Medicinal leeches (Hirudo medicinalis) are a standard treatment for venous congestion, a complication that can occur after reconstructive surgery. If the cause of venous congestion cannot be surgically corrected, then medicinal leeches are used to temporarily increase perfusion levels and maintain physiologic requirements within the congested tissue. Leeches increase perfusion within congested tissue by actively drawing off blood as a bloodmeal. Furthermore, the leech bite continues to bleed and relieve congestion after detachment because of the anticoagulation effects of leech saliva left behind in the bite. In a porcine model, a 10 x 10 cm cutaneous flank flap was congested by clamping the venae comitantes. Four medicinal leeches were allowed to attach to the congested flap, and parameters of active feeding and passive bleeding after detachment were recorded. The average bloodmeal volume for the medicinal leeches was 2.45 ml. Average passive bleeding for the first 2 and 4 hours after leech detachment totaled 2.21 and 2.50 ml, respectively, with 90 percent of passive bleeding occurring within 5 hours after detachment. Laser Doppler imaging indicated that the spatial arrangement of surface perfusion increases were localized to a 1.6-cm-diameter circle around the leech head (bite) and corresponded well with the visual return of normal skin tones to the same area. This study provides a realistic and quantitative estimate of the spatial and volumetric characteristics of leech feeding and passive bleeding using a clinically relevant model of acute, severe congestion.

  12. 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)

  13. 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...

  14. 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…

  15. Estimation of Congestion in Free Disposal Hull Models Using Data Envelopment Analysis

    PubMed Central

    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. PMID:25379531

  16. 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. PMID:25379531

  17. Investigation of Global Performance Affected by Congestion Avoiding Behavior in Theme Park Problem

    NASA Astrophysics Data System (ADS)

    Kawamura, Hidenori; Kataoka, Takashi; Kurumatani, Koichi; Ohuchi, Azuma

    We focus on the simple theme park problem, where there are two attractions and visitor agents which select their destination attraction based on congestion disregarding behavior and congestion avoiding behavior. According to the computer simulation, the result shows that the growth of individual congestion avoiding behavior is not always effective for improving global performance, and this phenomenon is caused by the oscillation of successive selection switching of the same destination by many congestion avoiding agents. Although the model and setting of this paper is simpler than other related works, we consider each phenomenon in those works has the same characteristic based on the ineffectiveness caused by the homogeneity of congestion avoiding behavior and information sharing.

  18. Venous Congestion, Endothelial and Neurohormonal Activation in Acute Decompensated Heart Failure: Cause or Effect?

    PubMed Central

    Colombo, Paolo C.; Doran, Amanda C.; Onat, Duygu; Wong, Ka Yuk; Ahmad, Myra; Sabbah, Hani N.; Demmer, Ryan T.

    2015-01-01

    Venous congestion and endothelial and neurohormonal activation are known to occur in acute decompensated heart failure (ADHF), yet the temporal role of these processes in the pathophysiology of decompensation is not fully understood. Conventional wisdom presumes congestion to be a consequence of worsening cardiovascular function; however, the biomechanically driven effects of venous congestion are biologically plausible contributors to ADHF that remain largely unexplored in vivo. Recent experimental evidence from human models suggests that fluid accumulation and venous congestion are not simply consequences of poor cardiovascular function, but rather are fundamental pro-oxidant, pro-inflammatory, and hemodynamic stimuli that contribute to acute decompensation. The latest advances in the monitoring of volume status using implantable devices allow for the detection of venous congestion before symptoms arise. This may ultimately lead to improved treatment strategies including not only diuretics, but also specific, adjuvant interventions to counteract endothelial and neurohormonal activation during early preclinical decompensation. PMID:25740404

  19. 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.

  20. An evaluation of nasal response following different treatment regimes of oxymetazoline with reference to rebound congestion.

    PubMed

    Morris, S; Eccles, R; Martez, S J; Riker, D K; Witek, T J

    1997-01-01

    This was a randomized, double-blind vehicle controlled study aimed at investigating the effects on nasal function of 7 days treatment with the topical decongestant oxymetazoline (0.05% w/v). Fifty healthy volunteers took part in the study and these were randomly allocated to three treatment groups (i) daily oxymetazoline (b.i.d. 150 microliters per nostril) (ii) intermittent oxymetazoline, with oxymetazoline being substituted for vehicle at the morning doses on days 1, 3, and 7; and (iii) daily vehicle (b.i.d. 150 microliters per nostril). The nasal airway was assessed by measurement of nasal airway resistance (NAR) using posterior rhinomanometry, subjective scaling of nasal patency by means of a visual analogue scale (VAS), and clinical visual examination. On days 1, 2, 3, and 7, NAR and VAS measurements were obtained before the morning dose and up to 6 hours after dosing; clinical visual examinations were also performed before dosing on these days. NAR and VAS measurements were also made following withdrawal of treatment on Days 8 and 9. Nonparametric analysis of the results showed that therapeutic tolerance to oxymetazoline did not develop over the 7-day treatment period, and visual examination of the nasal mucosa failed to find significant evidence of rhinitis. Evidence of rebound nasal congestion was found following 3 days of oxymetazoline treatment, with baseline NAR within the daily and intermittent oxymetazoline groups being significantly greater on Day 3 compared to Day 1 (p < 0.05). However, there was a trend toward increasing baseline NAR in the vehicle group over the course of the study, suggesting that the vehicle may have contributed to the rebound congestion. Following the withdrawal of treatments, only the intermittent oxymetazoline group had significantly higher NAR on Days 8 and 9 compared to Day 1 (p < 0.05). Subjective VAS measurements generally followed trends in NAR.

  1. Road Usage Heterogeneity and Mitigation of Traffic Congestion

    NASA Astrophysics Data System (ADS)

    Gomzalez, Marta C.; Wang, Pu

    2012-02-01

    Road networks form the backbone of the social and economic life of a city. Until recently, however, data have not been available to study the impact of trip selection on traffic congestion at an urban scale. To that end, we combined the most complete record of daily trips with the detailed road GIS data to analyze the road usage patterns in two US metropolitan areas. We classify the importance of road segments based on their ability to attract drivers from diverse sources and find that most of them are mainly used by drivers from very few sources. Thanks to this heterogeneity, we find that it is possible to design an efficient strategy to largely reduce the travel time in the road system.

  2. Congestive heart failure from suspected ductal closure in utero.

    PubMed

    Arcilla, R A; Thilenius, O G; Ranniger, K

    1969-07-01

    This is the 1st case report of a ductal closure occurring during fetal growth. The case was a spontaneous delivery in cephalic presentation from a 31-year-old gravida 3, para 3 Black woman who had been treated with isoniazid and spreptomycin up to 2 months before her delivery. Gestational age was 37 weeks when the fetus was delivered weighing 3.15 kgm. The cord had been wrapped around the fetus's neck, and breathing was delayed 2 minutes. In the nursery, the baby's general condition was poor, and congestive heart failure was diagnosed. The newborn had trieuspid insufficiency, severe heart failure, and acidosis at birth. These disappeared the next day. Hemodynamic studies when the baby was 4 hours old showed a large cone-shaped ductus arteriousus extending from the pulmonary artery but ending blindly at the aortic end.

  3. 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.

  4. I/O Congestion Avoidance via Routing and Object Placement

    SciTech Connect

    Dillow, David A; Shipman, Galen M; Oral, H Sarp; Zhang, Zhe

    2011-01-01

    As storage systems get larger to meet the the demands of petascale systems, careful planning must be applied to avoid congestion points and extract the maximum performance. In addition, the large size of the data sets generated by such systems makes it desirable for all compute resources in a center to have common access to this data without needing to copy it to each machine. This paper describes a method of placing I/O close to the storage nodes to minimize contention on Cray's SeaStar2+ network, and extends it to a routed Lustre configuration to gain the same benefits when running against a center-wide file system. Our experiments show performance improvements for both direct attached and routed file systems.

  5. 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

  6. Acquired post-traumatic aortic coarctation presenting as new-onset congestive heart failure: treatment with endovascular repair.

    PubMed

    Thompson, Norris B; Hamidian Jahromi, Alireza; Ballard, David H; Rao, Vyas R; Samra, Navdeep S

    2015-01-01

    Acquired coarctation of the thoracic aorta is a rare phenomenon in adults. The etiology is often idiopathic, but severe stenosis can develop from prior surgery, blunt thoracic aortic injuries, or severe atherosclerotic/atheroembolic disease. Common symptomatic presentations include refractory upper extremity hypertension and new-onset congestive heart failure. We present the case of a 52-year-old man who developed acquired thoracic aortic coarctation 30 years after a blunt trauma and deceleration injuries to the aorta requiring open surgical aortic repair. He presented with poorly controlled hypertension and new-onset heart failure and was treated surgically with endovascular repair.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. Recovery of chylous pulmonary congestion in tuberous sclerosis complex-associated lymphangioleiomyomatosis

    PubMed Central

    Kinoshita, Yoshiaki; Sakamoto, Atsuhiko; Hidaka, Kouko

    2014-01-01

    Chyloptysis and chylous pulmonary congestion are extremely rare complications of lymphangioleiomyomatosis (LAM). We report a case of a 50-year-old woman with tuberous sclerosis complex-associated LAM, who presented with expectorating milky-white bronchial casts. She was diagnosed with chyloptysis and chylous pulmonary congestion by sputum analysis. Her symptoms and lung infiltration were improved by oral sirolimus therapy; moreover, serum Krebs von den Lungen-6 (KL-6) levels paralleled the symptoms and lung infiltration of these complications. We suggest that serum KL-6 may be a useful monitoring biomarker of chyloptysis and chylous pulmonary congestion in LAM. PMID:25326562

  12. Hemostatic Markers in Congestive Heart Failure Dogs with Mitral Valve Disease

    PubMed Central

    Prihirunkit, Kreangsak; Sastravaha, Amornrate; Lekcharoensuk, Chalermpol; Chanloinapha, Phongsak

    2014-01-01

    Prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, D-dimer, antithrombin III (AT III), protein C (PC), factor VII (F.VII), and factor VIII (F.VIII), as well as hematocrit (HCT), platelets number (PLT), total plasma protein (TP), and albumin (ALB), were studied on fifty-eight congestive heart failure (CHF) dogs with mitral valve disease (MVD) and fifty control dogs. All of variables of MVD group, except APTT, were significantly different (P < 0.5) from control group. The variables were also compared among functional classes of CHF dogs and control dogs. It was determined that the higher the functional class of CHF dogs was, the greater the levels of fibrinogen and D-dimer were, whereas the lesser the activities of AT III and PC were presented. Additionally, TP had linear correlation with fibrinogen, D-dimer, HCT, and PLT (r = 0.31, 0.30, 0.43, and 0.38, resp., P < 0.5). These findings suggested that fibrinogen and D-dimer were the factors predisposing hypercoagulability through an increase in blood viscosity. The hemorheological abnormalities would shift an overall hemostatic balance toward a more thrombotic state in CHF dogs with MVD. PMID:26464938

  13. 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.

  14. Congestive heart failure with preserved ejection fraction is associated with severely impaired dynamic Starling mechanism

    PubMed Central

    Shibata, Shigeki; Hastings, Jeff L.; Prasad, Anand; Fu, Qi; Bhella, Paul S.; Pacini, Eric; Krainski, Felix; Palmer, M. Dean; Zhang, Rong

    2011-01-01

    Sedentary aging leads to increased cardiovascular stiffening, which can be ameliorated by sufficient amounts of lifelong exercise training. An even more extreme form of cardiovascular stiffening can be seen in heart failure with preserved ejection fraction (HFpEF), which comprises ∼40∼50% of elderly patients diagnosed with congestive heart failure. There are two major interrelated hypotheses proposed to explain heart failure in these patients: 1) increased left ventricular (LV) diastolic stiffness and 2) increased arterial stiffening. The beat-to-beat dynamic Starling mechanism, which is impaired with healthy human aging, reflects the interaction between ventricular and arterial stiffness and thus may provide a link between these two mechanisms underlying HFpEF. Spectral transfer function analysis was applied between beat-to-beat changes in LV end-diastolic pressure (LVEDP; estimated from pulmonary artery diastolic pressure with a right heart catheter) and stroke volume (SV) index. The dynamic Starling mechanism (transfer function gain between LVEDP and the SV index) was impaired in HFpEF patients (n = 10) compared with healthy age-matched controls (n = 12) (HFpEF: 0.23 ± 0.10 ml·m−2·mmHg−1 and control: 0.37 ± 0.11 ml·m−2·mmHg−1, means ± SD, P = 0.008). There was also a markedly increased (3-fold) fluctuation of LV filling pressures (power spectral density of LVEDP) in HFpEF patients, which may predispose to pulmonary edema due to intermittent exposure to higher pulmonary capillary pressure (HFpEF: 12.2 ± 10.4 mmHg2 and control: 3.8 ± 2.9 mmHg2, P = 0.014). An impaired dynamic Starling mechanism, even more extreme than that observed with healthy aging, is associated with marked breath-by-breath LVEDP variability and may reflect advanced ventricular and arterial stiffness in HFpEF, possibly contributing to reduced forward output and pulmonary congestion. PMID:21310890

  15. The Role of Congestion in Cardiorenal Syndrome Type 2: New Pathophysiological Insights into an Experimental Model of Heart Failure

    PubMed Central

    Angelini, Annalisa; Castellani, Chiara; Virzì, Grazia Maria; Fedrigo, Marny; Thiene, Gaetano; Valente, Marialuisa; Ronco, Claudio; Vescovo, Giorgio

    2015-01-01

    Background In cardiorenal syndrome type 2 (CRS2), the role of systemic congestion in heart failure (HF) is still obscure. We studied a model of CRS2 [monocrotaline (MCT)-treated rats] secondary to pulmonary hypertension and right ventricular (RV) failure in order to evaluate the contribution of prevalent congestion to the development of kidney injury. Methods Ten animals were treated with MCT for 4 weeks until they developed HF. Eleven animals were taken as controls. Signs of hypertrophy and dilatation of the right ventricle demonstrated the occurrence of HF. Brain natriuretic peptide (BNP), serum creatinine (sCreatinine), both kidney and heart neutrophil gelatinase-associated lipocalin (NGAL), matrix metallopeptidase 9 (MMP9), serum cytokines as well as kidney and heart cell death, as assessed by TUNEL, were studied. Results Rats with HF showed higher BNP levels [chronic HF (CHF) 4.8 ± 0.5 ng/ml; controls 1.5 ± 0.2 ng/ml; p < 0.0001], marked RV hypertrophy and dilatation (RV mass/RV volume: CHF 1.46 ± 0.31, controls 2.41 ± 0.81; p < 0.01) as well as pleural and peritoneal effusions. A significant increase in proinflammatory cytokines and sCreatinine was observed (CHF 3.06 ± 1.3 pg/ml vs. controls 0.54 ± 0.23 pg/ml; p = 0.04). Serum (CHF 562.7 ± 93.34 ng/ml vs. controls 245.3 ± 58.19 ng/ml; p = 0.02) as well as renal and heart tissue NGAL levels [CHF 70,680 ± 4,337 arbitrary units (AU) vs. controls 32,120 ± 4,961 AU; p = 0.001] rose significantly, and they were found to be complexed with MMP9 in CHF rats. A higher number of kidney TUNEL-positive tubular cells was also detected (CHF 114.01 ± 45.93 vs. controls 16.36 ± 11.60 cells/mm2; p = 0.0004). Conclusion In this model of CHF with prevalent congestion, kidney injury is characterized by tubular damage and systemic inflammation. The upregulated NGAL complexed with MMP9 perpetuates the vicious circle of kidney/heart damage by enhancing the enzymatic activity of MMP9 with extracellular matrix degradation

  16. 76 FR 75875 - Plan for Conduct of 2012 Electric Transmission Congestion Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-05

    ... electric transmission congestion pursuant to section 216(a)(1) of the Federal Power Act (76 FR 70122). This.... Hoffman, Assistant Secretary, Office of Electricity Delivery and Energy Reliability. BILLING CODE...

  17. Computational realizations of the entropy condition in modeling congested traffic flow. Final report

    SciTech Connect

    Bui, D.D.; Nelson, P.; Narasimhan, S.L.

    1992-04-01

    Existing continuum models of traffic flow tend to provide somewhat unrealistic predictions for conditions of congested flow. Previous approaches to modeling congested flow conditions are based on various types of special treatments at the congested freeway sections. Ansorge (Transpn. Res. B, 24B(1990), 133-143) has suggested that such difficulties might be substantially alleviated, even for the simple conservation model of Lighthill and Whitman, if the entropy condition were incorporated into the numerical schemes. In this report the numerical aspects and effects of incorporating the entropy condition in congested traffic flow problems are discussed. Results for simple scenarios involving dissipation of traffic jams suggest that Godnunov's method, which in a numerical technique that incorporates the entropy condition, is more accurate than two alternative methods. Similarly, numerical results for this method, applied to simple model problems involving formation of traffic jams, appear at least as realistic as those obtained from the well-known code of FREFLO.

  18. 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.

  19. 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.

  20. 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.

  1. Serum digoxin concentrations in canine congestive heart failure.

    PubMed

    Tobias, A H; Bland-van den Berg, P; Kruse, M M; Tubbesing, U H; Berry, W L

    1989-03-01

    Digoxin was administered to dogs (n = 10) in congestive heart failure, at an oral dosage rate of 0.01 mg kg-1 lean body mass twice daily. Lean body mass was determined by reducing gross mass by the estimated degree of ascites and body fat. The dose was further adjusted for factors such as renal and hepatic function, the bioavailability of different formulations, and the size of the patient. Trough and peak serum digoxin concentrations were determined after 10 days of digitalisation, or when signs of toxicity became apparent. Serum digoxin concentrations in 6 of the 10 dogs were found to be partially or completely in the toxic or subtherapeutic range. This indicates that an oral digoxin dosage rate of 0.01 mg kg-1 lean body mass administered twice daily, even when adjusted appropriately for factors that affect digoxin pharmacokinetics, provides no more than a rough approximation of the precise dose required to provide serum digoxin concentrations within the therapeutic range. The observations also lend support to a recent recommendation that the digoxin dosage rate should be based on body surface area, although even when administered on this basis, serum digoxin concentrations outside of the therapeutic range could be anticipated. PMID:2724277

  2. [Case of congestive heart failure associated with hypereosinophilia developed during antibiotics treatment].

    PubMed

    Sato, Takeo; Hagiwara, Kiyofumi; Matsuno, Hiroaki; Akiyama, Osamu

    2005-10-01

    A 92-year-old man with a history of bronchial asthma and allergic rhinitis received antibiotics for sepsis by methicillin-resistant Staphylococcus aureus and multidrug-resistant Enterococcus gallinarum. During the antibiotics treatment, skin eruptions, liver dysfunction, and hypereosinophilia developed, followed by dyspnea, congestive heart failure, electrocardiographic abnormalities, and diffuse mild myocardial hypokinesis. After the discontinuation of the antibiotics and the administration of steroid, skin eruptions, liver dysfunction, and hypereosinophilia improved parallel with the improvement of the congestive heart failure. Vancomycin hydrochloride and teicoplanin were suspected as the causative drugs on the basis of the treatment course. Although congestive heart failure is rare in the case of drug-induced hypereosinophilia, it is one of life-threatening complications. We describe herein a case of congestive heart failure associated with hypereosinophilia developed during antibiotics treatment, successfully treated with steroid after the discontinuation of the causative drug. PMID:16407668

  3. Device therapy in the management of congestive heart failure.

    PubMed

    Turer, Aslan T; Rao, Sunil V

    2005-01-01

    Despite significant advancements in the treatment of heart failure over the past 2 decades, this patient population is still subject to considerably high morbidity and mortality rates. In recent years, the field of device therapy as adjunctive treatment to the medical management of congestive heart failure has grown in the wake of the large number of randomized trials that have demonstrated the safety and efficacy of these devices. The implantable defibrillator currently represents the standard of care in certain segments of the heart failure population, even in those without a prior arrhythmic event. Biventricular pacing systems appear to have a role in heart failure patients with prolongation of their QRS duration in improving ventricular performance and symptoms, if not mortality. Last, the shortage of organs available for orthotopic transplant has heightened interest in using ventricular-assist devices as destination therapy, and although there is evidence for the feasibility for this approach at the current time, there is a next generation of devices that appear even more promising.

  4. 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.

  5. Atrioventricular valvular insufficiency and congestive heart failure in a carpet python.

    PubMed

    Rishniw, M; Carmel, B P

    1999-09-01

    Right atrioventricular valve insufficiency and bilateral congestive heart failure were identified in a carpet python (Morelia spilota variegata) with the aid of colour Doppler echocardiography, electrocardiography and radiography. The snake failed to respond to diuretic therapy and was euthanased. Based on this case, it appears that bilateral congestive failure is feasible in univentricular animals with lesions restricted to one side of the heart. Loop diuretic therapy may be inappropriate in non-crocodilian reptiles because reptiles lack a loop of Henle.

  6. Machine-Type-Communication (MTC) Device Grouping Algorithm for Congestion Avoidance of MTC Oriented LTE Network

    NASA Astrophysics Data System (ADS)

    Jung, Kwang-Ryul; Park, Aesoon; Lee, Sungwon

    Machine-Type-Communication (MTC) is a new paradigm in mobile wireless network domains such as Mobile WiMAX (IEEE 802.16e) and 3GPP LTE (3rd Generation Partnership Project Long Term Evolution). We explain the background for MTC environments, and its key issues. Then we focus on the uplink traffic aggressiveness characteristics in major applications such as Smart Grid. Then, we propose a new congestion avoidance algorithm to reduce the congestion of the uplink intensive applications.

  7. Immediate use of medicinal leeches to salvage venous congested reverse pedicled neurocutaneous flaps.

    PubMed

    Gideroglu, Kaan; Yildirim, Serkan; Akan, Mithat; Akoz, Tayfun

    2003-01-01

    Reverse pedicled neurocutaneous flaps have recently become popular for reconstructing soft tissue defects of the lower extremity. Venous congestion is a relatively common problem in these flaps in diabetic patients and those with electric burns, and this may cause partial or complete loss if capillary perfusion is not re-established urgently. We describe our experience of 13 neurocutaneous flaps, of which five developed venous congestion and were treated successfully with leeches placed immediately.

  8. 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.

  9. Increased production of nitric oxide in coronary arteries during congestive heart failure.

    PubMed Central

    O'Murchu, B; Miller, V M; Perrella, M A; Burnett, J C

    1994-01-01

    Experiments were designed to determine whether a heterogeneity of endothelium-dependent relaxations in arteries from different vascular beds exists in experimental congestive heart failure (CHF) and to determine the mediators of those responses. CHF was produced in dogs by rapid ventricular pacing for 15 d. Rings of coronary, femoral, and renal arteries with and without endothelium from control and CHF dogs were suspended in organ chambers for measurement of isometric force. In arteries contracted with prostaglandin F2 alpha, endothelium-dependent relaxations to BHT 920 (an alpha 2-adrenergic agonist) were increased in coronary arteries from dogs with CHF (maximal relaxation: control -15 +/- 9% vs CHF -92 +/- 5%; n = 5-6; P < 0.05), with a modest enhancement in renal arteries. Relaxations to adenosine diphosphate and the calcium ionophore were unchanged. Relaxations to BHT 920 in CHF were reduced by NG monomethyl-L-arginine (L-NMMA) and pertussis toxin but not by indomethacin. These data suggest that endothelium-dependent relaxations are affected heterogeneously in CHF. The enhanced response to alpha 2-adrenergic agonists in the coronary artery is mediated by nitric oxide through a mechanism sensitive to inhibition by pertussis toxin. This selective increase in endothelium-dependent relaxations in the coronary artery may contribute to preserving coronary blood flow during CHF. Images PMID:8282783

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  11. 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.

  12. 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.

  13. 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

  14. Simulation and analysis of congestion risk during escalator transfers using a modified social force model

    NASA Astrophysics Data System (ADS)

    Li, Wenhang; Gong, Jianhua; Yu, Ping; Shen, Shen; Li, Rong; Duan, Qishen

    2015-02-01

    The congestion risk during escalator transfers was simulated based on a modified social force model. A four-stage transfer model was proposed. A projection strategy was employed to calculate the social forces for inclined surfaces, and a schedule-line model was proposed to calculate the targets adaptively. Realistic simulations of escalator transfer activities were achieved. The results demonstrate that the spatial distribution of the congestion risks is inhomogeneous. A few areas contain clearly higher risks, and the congestion risk is higher in the transfer aisles than on the escalators. The congestion risk in the transfer aisle is influenced more by the average pedestrian speed than that of the escalators. Slower walkers in the transfer aisle may cause congestion, which is more serious when the escalator speed is faster than that of the pedestrians. Therefore, to reduce the congestion risk, the speed of the escalator should be set slower than the average speed of the pedestrians, and conductors can be employed to divert the traffic at the entrance, turns, and exit of the escalator.

  15. 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. PMID:25780910

  16. 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.

  17. 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. PMID:27649412

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

    PubMed Central

    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. PMID:27649412

  19. Utilizing Joint Routing and Capacity Assignment Algorithms to Achieve Inter- and Intra-Group Delay Fairness in Multi-Rate Multicast Wireless Sensor Networks

    PubMed Central

    Lin, Frank Yeong-Sung; Hsiao, Chiu-Han; Lin, Leo Shih-Chang; Wen, Yean-Fu

    2013-01-01

    Recent advance in wireless sensor network (WSN) applications such as the Internet of Things (IoT) have attracted a lot of attention. Sensor nodes have to monitor and cooperatively pass their data, such as temperature, sound, pressure, etc. through the network under constrained physical or environmental conditions. The Quality of Service (QoS) is very sensitive to network delays. When resources are constrained and when the number of receivers increases rapidly, how the sensor network can provide good QoS (measured as end-to-end delay) becomes a very critical problem. In this paper; a solution to the wireless sensor network multicasting problem is proposed in which a mathematical model that provides services to accommodate delay fairness for each subscriber is constructed. Granting equal consideration to both network link capacity assignment and routing strategies for each multicast group guarantees the intra-group and inter-group delay fairness of end-to-end delay. Minimizing delay and achieving fairness is ultimately achieved through the Lagrangean Relaxation method and Subgradient Optimization Technique. Test results indicate that the new system runs with greater effectiveness and efficiency. PMID:23493123

  20. Utilizing joint routing and capacity assignment algorithms to achieve inter- and intra-group delay fairness in multi-rate multicast wireless sensor networks.

    PubMed

    Lin, Frank Yeong-Sung; Hsiao, Chiu-Han; Lin, Leo Shih-Chang; Wen, Yean-Fu

    2013-03-14

    Recent advance in wireless sensor network (WSN) applications such as the Internet of Things (IoT) have attracted a lot of attention. Sensor nodes have to monitor and cooperatively pass their data, such as temperature, sound, pressure, etc. through the network under constrained physical or environmental conditions. The Quality of Service (QoS) is very sensitive to network delays. When resources are constrained and when the number of receivers increases rapidly, how the sensor network can provide good QoS (measured as end-to-end delay) becomes a very critical problem. In this paper; a solution to the wireless sensor network multicasting problem is proposed in which a mathematical model that provides services to accommodate delay fairness for each subscriber is constructed. Granting equal consideration to both network link capacity assignment and routing strategies for each multicast group guarantees the intra-group and inter-group delay fairness of end-to-end delay. Minimizing delay and achieving fairness is ultimately achieved through the Lagrangean Relaxation method and Subgradient Optimization Technique. Test results indicate that the new system runs with greater effectiveness and efficiency.

  1. 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.

  2. 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).

  3. Cheyne-Stokes respiration and prognosis in congestive heart failure.

    PubMed

    Andreas, S; Hagenah, G; Moller, C; Werner, G S; Kreuzer, H

    1996-12-01

    Patients with congestive heart failure (CHF) frequently demonstrate Cheyne-Stokes respiration (CSR) with repetitive arousals and oxygen desaturations during sleep. Although it was evident from early publications that CSR during the daytime is a poor prognostic indicator in patients with CHF, it was speculated recently that CSR occurring during sleep could impede left ventricular function and even survival. We therefore followed up 36 patients with CHF and a left ventricular ejection fraction < or = 40% who underwent a sleep study at our institution. The patients showed a reduced ejection fraction (20 +/- 8%) and CSR with a median of 19% of total sleep time (lower and upper quartiles 9% and 56%). In 12 +/- 9% of their time in bed, the arterial oxygen saturation was <90%. No patient was lost to follow-up, which lasted for 32 +/- 15 months (range 11 to 53). One-year survival was 86 +/- 6%, and 2-year survival was 66 +/- 8%. Univariate comparisons for survival between groups stratified by the amount of CSR revealed no significant difference (log rank test, p = 0.84). However, the 20 patients with a left ventricular ejection fraction <20% had a shorter mean survival time than patients with an ejection fraction >20% (9.5 vs 28.3 months; log rank test, p = 0.013). Two patients with CSR during the daytime died within 1 month. No other patient had CSR during the daytime, and only 1 patient without daytime CSR died within 1 month (chi-square test, p <0.001). Higher age, reduced carbon dioxide end-tidal partial pressure, and increased transit time were found to be significantly related to the amount of nocturnal CSR. In conclusion, CSR occurring during sleep has no important prognostic impact in patients with CHF, but CSR present during the daytime suggests a high likelihood of dying within a few months.

  4. 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.

  5. 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. PMID:27428495

  6. 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.

  7. 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. PMID:26304695

  8. Ephedrine QoS: An Antidote to Slow, Congested, Bufferless NoCs

    PubMed Central

    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%. PMID:25250386

  9. Physical Activity during a Prolonged Congested Period in a Top-Class European Football Team

    PubMed Central

    Djaoui, Léo; Wong, Del P.; Pialoux, Vincent; Hautier, Christophe; Da Silva, Cristiano D.; Chamari, Karim; Dellal, Alexandre

    2013-01-01

    Purpose The aim of the present study was to examine the variation in physical activity of elite soccer players within successive prolonged periods of fixture congestion over 5 months of competition during the competitive season 2011-2012. Methods Sixteen international players, classified into 6 positions (central defenders: CD; full-backs: FB; central defensive midfielders: CDM; wide midfielders: WM; central attacking midfielders: CAM; forwards: FW), were examined during the French First League, French Cup, and UEFA Champion's League matches. The total distance covered at light (<12 km.h−1), sustained-cruising (>18-21 km.h−1), high (>21-23 km.h−1), very high (>23-25 km.h−1), sub-maximal (>25-27 km.h−1), and maximal (>27 km.h−1) intensity running (IR) were measured and analysed using a semi-automatic match analysis system (Amisco Pro™). Results No differences were observed between congested and non-congested periods (two vs. one match a week, respectively) for the total distance covered at all the speed thresholds over 18 km.h−1, with no variation in physical fitness over the 5 studied months. Specifically to the playing positions, regardless of the congestion periods, FB and WM covered more distance than CDM over 21km.h−1; FB, WM and FW covered similar distances for all running intensities; and CD and CDM covered shorter distance during non-congested compared to congested periods (P<0.05) at light-IR. Conclusion The present study reveals that prolonged congested match fixture did not affect the high-intensity physical activity of top-class soccer players during official games during a 5 months fixture period. PMID:24868431

  10. Tolvaptan Improves the Long-Term Prognosis in Patients With Congestive Heart Failure With Preserved Ejection Fraction as Well as in Those With Reduced Ejection Fraction.

    PubMed

    Imamura, Teruhiko; Kinugawa, Koichiro

    2016-09-28

    Tolvaptan (TLV), an arginine vasopressin type 2 antagonist, has been shown to play a role in ameliorating symptomatic congestion and normalizing diluted hyponatremia in patients with congestive heart failure (HF). However, most evidence was derived from patients with HF with reduced ejection fraction (HFrEF), and the clinical efficacy of TLV in patients with HF with preserved ejection fraction (HFpEF) remains uncertain. In this study, we retrospectively enrolled 60 in-hospital patients with stage D HF, who had received TLV to treat symptomatic congestion at our institute between 2011 and 2013. As a control group, we also enrolled 60 background-matched HF patients who did not receive TLV therapy. Patients with HFpEF (n = 29), whose left ventricular ejection fraction was > 45%, had higher age and a lower urine aquaporin-2 level relative to the plasma arginine vasopressin concentration compared with those with HFrEF (n = 91). TLV therapy significantly reduced the 2-year readmission rates in both the HFrEF and HFpEF populations (P < 0.05 for both), indicating that TLV therapy may improve the long-term prognosis not only in patients with HFrEF but also in those with HFpEF. PMID:27581675

  11. Tolvaptan Improves the Long-Term Prognosis in Patients With Congestive Heart Failure With Preserved Ejection Fraction as Well as in Those With Reduced Ejection Fraction.

    PubMed

    Imamura, Teruhiko; Kinugawa, Koichiro

    2016-09-28

    Tolvaptan (TLV), an arginine vasopressin type 2 antagonist, has been shown to play a role in ameliorating symptomatic congestion and normalizing diluted hyponatremia in patients with congestive heart failure (HF). However, most evidence was derived from patients with HF with reduced ejection fraction (HFrEF), and the clinical efficacy of TLV in patients with HF with preserved ejection fraction (HFpEF) remains uncertain. In this study, we retrospectively enrolled 60 in-hospital patients with stage D HF, who had received TLV to treat symptomatic congestion at our institute between 2011 and 2013. As a control group, we also enrolled 60 background-matched HF patients who did not receive TLV therapy. Patients with HFpEF (n = 29), whose left ventricular ejection fraction was > 45%, had higher age and a lower urine aquaporin-2 level relative to the plasma arginine vasopressin concentration compared with those with HFrEF (n = 91). TLV therapy significantly reduced the 2-year readmission rates in both the HFrEF and HFpEF populations (P < 0.05 for both), indicating that TLV therapy may improve the long-term prognosis not only in patients with HFrEF but also in those with HFpEF.

  12. Genetic susceptibility to anthracycline-related congestive heart failure in survivors of haematopoietic cell transplantation.

    PubMed

    Armenian, Saro H; Ding, Yan; Mills, George; Sun, Canlan; Venkataraman, Kalyanasundaram; Wong, Florence Lennie; Neuhausen, Susan L; Senitzer, David; Wang, Shirong; Forman, Stephen J; Bhatia, Smita

    2013-10-01

    Haematopoietic cell transplantation (HCT) survivors are at increased risk for developing congestive heart failure (CHF), primarily due to pre-HCT exposure to anthracyclines. We examined the association between the development of CHF after HCT and polymorphisms in 16 candidate genes involved in anthracycline metabolism, iron homeostasis, anti-oxidant defence, and myocardial remodelling. A nested case-control study design was used. Cases (post-HCT CHF) were identified from 2950 patients who underwent HCT between 1988 and 2007 at City of Hope and had survived ≥1 year. This cohort formed the sampling frame for selecting controls (without CHF) matched on: age, race/ethnicity, cumulative anthracycline exposure, stem cell source (allogeneic, autologous), and length of follow-up. Seventy-seven cases with pre-HCT germline DNA and 178 controls were genotyped. Multivariate analysis revealed that the odds of CHF was higher in females [Odds Ratio (OR) = 2·9, P < 0·01], individuals with pre-HCT chest radiation (OR = 4·7, P = 0·05), hypertension (OR = 2·9, P = 0·01), and with variants of genes coding for the NAD(P)H-oxidase subunit RAC2 (rs13058338, 7508T→A; OR = 2·8, P < 0·01), HFE (rs1799945, 63C→G; OR = 2·5, P = 0·05) or the doxorubicin efflux transporter ABCC2 (rs8187710, 1515G→A; OR = 4·3, P < 0·01). A combined (clinical and genetic) CHF predictive model performed better [area under the curve (AUC), 0·79] than the genetic (AUC = 0·67) or the clinical (AUC = 0·69) models alone.

  13. 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.

  14. 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.

  15. Inflammatory Biomarkers in Refractory Congestive Heart Failure Patients Treated with Peritoneal Dialysis

    PubMed Central

    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. PMID:26539513

  16. Packet Traffic Dynamics Near Onset of Congestion in Data Communication Network Model

    NASA Astrophysics Data System (ADS)

    Lawniczak, A. T.; Tang, X.

    2006-05-01

    The dominant technology of data communication networks is the Packet Switching Network (PSN). It is a complex technology organized as various hierarchical layers according to the International Standard Organization (ISO) Open Systems Interconnect (OSI) Reference Model. The Network Layer of the ISO OSI Reference Model is responsible for delivering packets from their sources to their destinations and for dealing with congestion if it arises in a network. Thus, we focus on this layer and present an abstraction of the Network Layer of the ISO OSI Reference Model. Using this abstraction we investigate how onset of traffic congestion is affected for various routing algorithms by changes in network connection topology. We study how aggregate measures of network performance depend on network connection topology and routing. We explore packets traffic spatio-temporal dynamics near the phase transition point from free flow to congestion for various network connection topologies and routing algorithms. We consider static and adaptive routings. We present selected simulation results.

  17. Long-term outcome of patients with acromegaly and congestive heart failure.

    PubMed

    Bihan, Hélène; Espinosa, Consuelo; Valdes-Socin, Hernan; Salenave, Sylvie; Young, Jacques; Levasseur, Suzanne; Assayag, Patrick; Beckers, Albert; Chanson, Philippe

    2004-11-01

    Cardiovascular complications are a major cause of morbidity and mortality in patients with acromegaly. Normalization of GH secretion is associated with an improvement in structural and functional cardiac abnormalities. However, the long-term cardiac effects of treatment for acromegaly have not been studied in patients who have already developed chronic congestive heart failure (CHF). We reviewed the charts of 330 consecutive patients with acromegaly treated in two French and Belgian centers since 1985. Ten patients with both acromegaly and CHF (eight men, two women, mean age 49.7 yr) were studied retrospectively. One of them was excluded because CHF was due to severe aortic stenosis.CHF (New York Heart Association stages III-IV and echocardiography showing dilated hypokinetic cardiomyopathy with left ventricular systolic dysfunction and a left ventricular ejection fraction less than 45%) was diagnosed before, concomitantly, or after acromegaly in, respectively, two, five, and two patients. Three patients were referred with terminal heart failure requiring transplantation.One patient had transient CHF associated with a hypertensive crisis. The other eight patients had symptomatic chronic CHF. Control of GH hypersecretion failed, totally or partially, in three patients: one had a long-term survival, and the two others died at 1 and 5 yr. Good GH control was achieved in five patients: four of these are still alive 2-16 yr after diagnosis of CHF, their clinical status is stable or improved, and their quality of life is good. Overall, the 1- and 5-yr mortality (or transplantation) rates for patients with chronic symptomatic CHF were 25% (2 of 8 patients) and 37.5% (3 of 8 patients), respectively. In conclusion, less than 3% of acromegalic patients developed CHF in this study. Although effective treatment of acromegaly improved short-term cardiovascular status, its impact on long-term survival is questionable.

  18. Transitional Care for Patients With Congestive Heart Failure: A Systematic Review and Meta-Analysis

    PubMed Central

    Vedel, Isabelle; Khanassov, Vladimir

    2015-01-01

    PURPOSE We aimed to determine the impact of transitional care interventions (TCIs) on acute health service use by patients with congestive heart failure in primary care and to identify the most effective TCIs and their optimal duration. METHODS We conducted a systematic review and meta-analysis of randomized controlled trials, searching the Medline, PsycInfo, EMBASE, and Cochrane Library databases. We performed a meta-analysis to assess the impact of TCI on all-cause hospital readmissions and emergency department (ED) visits. We developed a taxonomy of TCIs based on intensity and assessed the methodologic quality of the trials. We calculated the relative risk (RR) and a 95% confidence interval for each outcome. We conducted a stratified analysis to identify the most effective TCIs and their optimal duration. RESULTS We identified 41 randomized controlled trials. TCIs significantly reduced risks of readmission and ED visits by 8% and 29%, respectively (relative risk = 0.92; 95% CI, 0.87–0.98; P = .006 and relative risk = 0.71; 95% CI, 0.51–0.98; P = .04). High-intensity TCIs (combining home visits with telephone followup, clinic visits, or both) reduced readmission risk regardless of the duration of follow-up. Moderate-intensity TCIs were efficacious if implemented for a longer duration (at least 6 months). In contrast, low-intensity TCIs, entailing only followup in outpatient clinics or telephone follow-up, were not efficacious. CONCLUSIONS Clinicians and managers who implement TCIs in primary care can incorporate these results with their own health care context to determine the optimal balance between intensity and duration of TCIs. High-intensity interventions seem to be the best option. Moderate-intensity interventions implemented for 6 months or longer may be another option. PMID:26553896

  19. Beta-adrenoceptor mediated signal transduction in congestive heart failure in cardiomyopathic (UM-X7.1) hamsters.

    PubMed

    Kaura, D; Takeda, N; Sethi, R; Wang, X; Nagano, M; Dhalla, N S

    In view of the lack of information regarding the status of beta-adrenoceptor mediated signal transduction mechanisms at severe stages of congestive heart failure, the status of beta-adrenoceptors, G-proteins and adenylyl cyclase activities was examined in 220-275 day old cardiomyopathic hamster hearts. Although no changes in the Kd values for beta 1- and beta 2-adrenoceptors were seen, the number of beta 1-adrenoceptors, unlike that of beta 2-adrenoceptors, was markedly decreased in cardiac membranes from failing hearts. The activation of adenylyl cyclase in the failing hearts by different concentrations of isoproterenol was also attenuated in comparison to the control preparations. The basal adenylyl cyclase activity in cardiac membranes from the failing hearts was not altered; however, the stimulated enzyme activities, when measured in the presence of forskolin, NaF or Gpp(NH)p were depressed significantly. The functional activity of Gs-proteins (measured by cholera toxin stimulation of adenylyl cyclase) was depressed whereas that of Gi-proteins (measured by pertussis toxin stimulation of adenylyl cyclase) was increased in the failing hearts. Not only were the Gs- and Gi-protein contents (measured by immunoblotting) increased, the bioactivities of these proteins as determined by ADP-ribosylations in the presence of cholera toxin and pertussis toxin, respectively, were also higher in failing hearts in comparison to the control values. Northern blot analysis revealed that the signals for Gs- and Gi-protein mRNAs were augmented at this stage of heart failure. These results indicate that the loss of adrenergic support at severe stages of congestive heart failure in cardiomyopathic hamsters may involve a reduction in the number of beta 1-adrenoceptors, and an increase in Gi-protein contents as well as bioactivities in addition to an uncoupling of Gs-proteins from the catalytic site of adenylyl cyclase in cardiac membrane. PMID:8739246

  20. 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.

  1. "Venous congestion" as a cause of subcortical white matter T2 hypointensity on magnetic resonance images.

    PubMed

    Kamble, Jayaprakash Harsha; Parameswaran, Krishnan

    2016-01-01

    Subcortical T2 hypointensity is an uncommon finding seen in very limited conditions such as multiple sclerosis, Sturge-Weber syndrome, and meningitis. Some of the conditions such as moyamoya disease, severe ischemic-anoxic insults, early cortical ischemia, and infarcts are of "arterial origin." We describe two conditions in which "venous congestion" plays a major role in T2 hypointensity - cerebral venous sinus thrombosis (CVST) and dural arteriovenous fistula (dAVF). The third case is a case of meningitis, showing T2 hypointensity as well, and can be explained by the "venous congestion" hypothesis. The same hypothesis can explain few of the other conditions causing subcortical T2 hypointensity. PMID:27570403

  2. Is a red umbilical cord a sign of umbilical venous congestion?: a case report.

    PubMed

    Miyake, Hidehiko; Igarashi, Miwa; Inde, Yusuke; Nakai, Akihito; Suzuki, Shunji; Takeshita, Toshiyuki

    2011-01-01

    Postnatal examination of fetal appendages is important because this information may help predict perinatal outcome. We present a case of a red streak along the entire umbilical vein after a cesarean section due to non-reassuring fetal status. The pathological findings revealed an umbilical cord with dilated vascular changes and mild funisitis. Because the dilated change was intense in the umbilical vein, the red streak of the umbilical cord was caused by venous congestion. Moreover, we considered that the umbilical venous congestion was due to increased resistance in the fetal intra-abdominal umbilical vein, which was associated with the non-reassuring fetal status. PMID:21389648

  3. Study the mechanical pulmonary changes in patients with congestive heart failure (CHF) by impulse oscillometry

    PubMed Central

    Nourizadeh, Mohammad; Ghelich, Yunose; Amin, Ahmad; Eidani, Esmaeel; Gholampoor, Yousef; Asadmoghadam, Mahsa; Asadinia, Najme

    2013-01-01

    Background Heart failure is one of the most leading cause of death worldwide, but the mechanical characteristics of the pulmonary system in these patients have not been studied enough. The aim of this study was to measure mechanical pulmonary changes in patients with congestive heart failure (CHF) by using impulse oscillometry (IOS), which can obtain data by simpler means and independently from respiratory muscle strength. Materials and methods We assessed 24 CHF patients and 24 controls by spirometry and IOS using the Jaeger IOS system. IOS measures central and peripheral airway resistances (R20, R5) and central and peripheral reactances (X20, X5) using sound waves with different frequencies, which superimposed on the patients respiratory tidal volume and then records reflects. P value < 0.05 was taken to be significant. Results The mean age of patients and controls was 61 ± 10 and 57 ± 7 years, respectively. The mean ejection fraction (EF) was 37 ± 17% for patients and 55 ± 7% for controls. Patients had a lower X5 (−0.20 ± 0.13 vs −0.13 ± 0.07; P < 0.05), forced expiratory volume in 1 second (FEV1; 2.26 ± 0.68 vs 3.09 ± 0.82: P < 0.01 L/min), and forced vital capacity (FVC; 2.55 ± 0.86 vs 3.32 ± 0.87; P < 0.05) compared to the controls. They also had elevated R5: 0.37 ± 0.21 vs 0.27 ± 0.09; P < 0.06). X5 was correlated with spirometric abnormalities (P < 0.05) and was lower in patients than in controls. Conclusion X5 was lower and R5 was higher in patients than in controls. CHF patients can be assessed by IOS more comfortable than by spirometry. IOS can reliably measure peripheral airway resistance in this group of patients. PMID:24027371

  4. 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

  5. How many probe vehicles are enough for identifying traffic congestion?—a study from a streaming data perspective

    NASA Astrophysics Data System (ADS)

    Wang, Handong; Yue, Yang; Li, Qingquan

    2013-03-01

    Many studies have been carried out using vehicle trajectory to analyze traffic conditions, for instance, identifying traffic congestion. However, there is a lack of a systematic study on the appropriate number of probe vehicles and their sampling interval in order to identify traffic congestion accurately. Moreover, most of related studies ignore the streaming feature of trajectory data. This paper first represents a novel method of identifying traffic congestion considering the stream feature of vehicle trajectories. Instead of processing the whole data stream, a series of snapshots are extracted. Congested road segments can be identified by analyzing the clusters' evolution among a series of adjacent snapshots. We then calculated a series of parameters and their corresponding congestion identification accuracy. The results have implications for related probe vehicle deployment and traffic analysis; for example, when 5% of probe vehicles are available, 85% identification accuracy can be reached if the sampling time interval is 10 s.

  6. Pneumoconiosis increases the risk of congestive heart failure: A nationwide population-based cohort study.

    PubMed

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

    2016-06-01

    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/m).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/m). 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.

  7. Low-frequency blood flow oscillations in congestive heart failure and after β1-blockade treatment

    PubMed Central

    Bernjak, A.; Clarkson, P.B.M.; McClintock, P.V.E.; Stefanovska, A.

    2008-01-01

    Laser Doppler flowmetry (LDF) of forearm skin blood flow, combined with iontophoretically-administered acetylcholine and sodium nitroprusside and wavelet spectral analysis, was used for noninvasive evaluation of endothelial function in 17 patients newly diagnosed with New York Heart Association class II–III congestive heart failure (CHF). After 20 ± 10 weeks' treatment with a β1-blocker (Bisoprolol), the measurements were repeated. Measurements were also made on an age- and sex-matched group of healthy controls (HC). In each case data were recorded for 30 min. In HC, the difference in absolute spectral amplitude of LDF oscillations between the two vasodilators manifests in the frequency interval 0.005–0.0095 Hz (p < 0.01); this difference is initially absent in patients with CHF, but appears following the β1-blocker treatment (p < 0.01). For HC, the difference between the two vasodilators also manifests in normalised spectral amplitude in 0.0095–0.021 Hz (p < 0.05). This latter difference is absent in CHF patients and is unchanged by treatment with β1-blockers. It is concluded that there are two oscillatory skin blood flow components associated with endothelial function. Both are reduced in CHF. Activity in the lower frequency interval is restored by β1-blocker treatment, confirming the association between CHF and endothelial dysfunction but suggesting the involvement of two distinct mechanisms. PMID:18721820

  8. Pneumoconiosis increases the risk of congestive heart failure: A nationwide population-based cohort study.

    PubMed

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

    2016-06-01

    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/m).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/m). 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

  9. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... performance of the multimodal transportation system, identify the causes of recurring and non-recurring... causes of congestion, and evaluate the efficiency and effectiveness of implemented actions. To the extent... designated as nonattainment area for ozone or carbon monoxide pursuant to the Clean Air Act, Federal...

  10. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... performance of the multimodal transportation system, identify the causes of recurring and non-recurring... causes of congestion, and evaluate the efficiency and effectiveness of implemented actions. To the extent... designated as nonattainment area for ozone or carbon monoxide pursuant to the Clean Air Act, Federal...

  11. 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). 972.214 Section 972.214 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL LANDS HIGHWAYS FISH AND WILDLIFE SERVICE MANAGEMENT SYSTEMS Fish and Wildlife Service Management...

  12. 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,…

  13. 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…

  14. 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…

  15. 23 CFR 970.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... criteria, as appropriate, funded through the FLHP. (b) The NPS shall consider the results of the CMS when selecting congestion mitigation strategies that are the most time efficient and cost effective and that add...-metropolitan areas, consideration shall be given to strategies that promote alternative transportation...

  16. 23 CFR 973.214 - Indian lands congestion management system (CMS).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... the IRR transportation plan and the IRRTIP, when selecting strategies for implementation that provide... congestion and enhance mobility. (b) In addition to the requirements provided in § 973.204, the CMS must meet..., consideration shall be given to strategies that reduce private automobile travel and improve...

  17. 78 FR 67442 - Congestion Mitigation and Air Quality Improvement Program Interim Guidance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-12

    ... types of rail service in a January 16, 2002, Federal Register notice (67 FR 2278), and in a March 8... 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...

  18. Decisions, Decisions, Decisions: Recreation Site Choice with Expected Congestion and Social Interaction

    ERIC Educational Resources Information Center

    Snipes, Katherine H.

    2009-01-01

    A set of computer-based recreation choice experiments were run to examine the effect of expected congestion and social interactions on the decision making process. MouseTrace is a process-tracing program that recorded individual subject's information acquisitions and provided the necessary information to determine if subjects used attribute-based…

  19. 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 pricing was…

  20. The use of medical leeches for venous congestion. A review and case report.

    PubMed

    Buote, N J

    2014-01-01

    The medicinal leech, Hirudo medicinalis, has been used for hundreds of years in human medicine for a variety of diseases, most recently including venous congestion following reconstructive surgeries (skin flaps and reimplantations), excessive lingual and periorbital swelling, and non-traditional treatments for osteoarthritis, compartment syndrome and sialoadenitis. The treatment of venous congestion in animals using leeches has been mentioned anecdotally, but the only published report pertains to the use of leeches in a cat suffering from polycythemia vera. We report the use of medical grade leeches in a one-year-old male castrated Domestic Shorthaired cat presenting with severe swelling of the paw after sustaining a constrictive injury from a bandage. The limb use had become compromised and the swelling was not responsive to compression bandages so leech therapy was instituted for four days and the swelling dramatically improved. The patient's limb use improved back to normal and the constrictive wound went on to heal without complication. The use of leeches in this case allowed for resolution of severe venous congestion and a full return to function in this patient with no continued skin loss. The mechanism of action of hirudotherapy for venous congestion is to allow for an alternative egress of pooled venous blood leading to a reduction in capillary pressure and increases in arterial reperfusion of capillary beds. The human and veterinary applications, method, and potential complications with hirudotherapy are discussed in this review.

  1. Salvage of venous congestion using medicinal leeches for traumatic nasal flap.

    PubMed

    Jose, Mathew; Varghese, Jomy; Babu, Arun

    2015-03-01

    Medicinal leeches are extremely useful and safe in the salvage of venous outflow compromised tissue, particularly in digit replants and various forms of flaps. Although it is unusual for a partial soft tissue avulsion of the face to require medicinal leech therapy, situations may occur in which there is adequate arterial inflow but inadequate venous outflow. In such cases, medicinal leeches may play a very important role in salvaging the soft tissue segment. We report a case of a 34-year-old gentleman who showed signs of venous congestion following primary management for a traumatic nasal flap. Successful salvage of venous congestion was done using medicinal leech therapy, once daily, for 5 days. His recovery deemed satisfactory and uncomplicated. Medicinal leeches are well-known in the treatment of venous congestion or complete venous outflow obstruction in larger pedicled flaps and microvascular transfers. In trauma, it is well established that medicinal leeches are invaluable in treating venous congestion in digit replants and replantation of totally avulsed external ear segments. A limited number of other reports have demonstrated the use of medicinal leeches for salvage of other partially avulsed facial structures. Medicinal leeches have a significant role in the management of traumatic and microvascular flaps, the oral and maxillofacial surgeon should weigh the benefits of such treatment before instituting other expensive or complex treatment modalities.

  2. 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…

  3. Distinguishing congestion from malicious behavior in mobile ad-hoc networks

    NASA Astrophysics Data System (ADS)

    Ding, Jin; Medidi, Sirisha R.

    2004-08-01

    Packet dropping in Mobile Ad-hoc Networks could be a result of wireless link errors, congestion, or malicious packet drop attack. Current techniques for detecting malicious behavior either do not consider congestion in the network or are not able to detect in real time. Further more, they usually work at network layer. In this paper, we propose a TCP-Manet protocol, which reacts to congestion like TCP Reno protocol, and has additional capability to distinguish among congestion, wireless link error, and malicious packet drop attack. It is an end-to-end mechanism that does not require additional modifications to the nodes in the network. Since it is an extension of existing TCP protocol, it is compatible with existing protocols. It works in conjunction with the network layer and an unobtrusive monitor to assist the network in the detection and characterization of the nature of the behavior. Experimental results show that TCP-Manet has the same performance as that of TCP-Reno in wired network, and performs better in wireless ad-hoc networks in terms of throughput while having good detection effectiveness.

  4. 23 CFR 970.214 - Federal lands congestion management system (CMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... selecting congestion mitigation strategies that are the most time efficient and cost effective and that add...-metropolitan areas, consideration shall be given to strategies that promote alternative transportation systems, reduce private automobile travel, and best integrate private automobile travel with other...

  5. Transcatheter ovarian vein embolisation without renal vein stenting for pelvic venous congestion and nutcracker anatomy.

    PubMed

    Perkov, Dražen; Vrkić Kirhmajer, Majda; Novosel, Luka; Popić Ramač, Jelena

    2016-01-01

    The diagnosis of a nutcracker syndrome can be aggravated by overlap of a nutcracker phenomenon with other pathologies. In patients with nutcracker anatomy and predominantly pelvic congestion symptoms, ovarian vein embolization without left renal vein stenting could be considered a first line therapy. PMID:27428503

  6. 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). 972.214 Section 972.214 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL LANDS HIGHWAYS FISH AND WILDLIFE SERVICE MANAGEMENT SYSTEMS Fish and Wildlife Service Management...

  7. 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). 972.214 Section 972.214 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL LANDS HIGHWAYS FISH AND WILDLIFE SERVICE MANAGEMENT SYSTEMS Fish and Wildlife Service Management...

  8. The effects of congested fixtures period on tactical and physical performance in elite football.

    PubMed

    Folgado, Hugo; Duarte, Ricardo; Marques, Pedro; Sampaio, Jaime

    2015-01-01

    The aim of this study was to examine the physical and tactical performances of a professional football team under congested and non-congested fixture periods. Six home matches of an English professional football team were analysed during competitive season (3 matches distancing three days from the previous fixture and 3 matches distancing six or more days from the previous fixture). Players' physical performances were measured by the total distance covered and distance covered at different speed categories. Tactical performances were measured by the percentage of time of players' movement synchronisation of lateral and longitudinal displacements. This variable was calculated considering all the possible pairs of outfield players, for the overall match and at different speed categories. Results showed no differences in the physical performance, although players' spent more time synchronised during the non-congested fixtures compared to congested fixtures, both for lateral (41.26% to 38.51%, ES: -0.3, P < 0.001) and longitudinal displacements (77.22% to 74.48%, ES: -0.5, P < 0.001). These coordination differences were particularly evident at the lower speed categories and in dyads composed by positions that tend to be further apart during the match, typically central and wing positioned players. Tactical performance seems to be affected by fixtures distribution, with players' spending more time synchronised during the non-congested fixtures. As players' cover the same amount of distance at similar intensities in both fixtures distribution, this reduction of synchronisation may be associated with an increased perception of fatigue and consequent adaptation strategies.

  9. Risk of venous congestion in live donors of extended right liver graft

    PubMed Central

    Radtke, Arnold; Sgourakis, George; Molmenti, Ernesto P; Beckebaum, Susanne; Cicinnati, Vito R; Schmidt, Hartmut; Peitgen, Heinz-Otto; Broelsch, Christoph E; Malagó, Massimo; Schroeder, Tobias

    2015-01-01

    AIM: To investigate middle hepatic vein (MHV) management in adult living donor liver transplantation and safer remnant volumes (RV). METHODS: There were 59 grafts with and 12 grafts without MHV (including 4 with MHV-5/8 reconstructions). All donors underwent our five-step protocol evaluation containing a preoperative protocol liver biopsy Congestive vs non-congestive RV, remnant-volume-body-weight ratios (RVBWR) and postoperative outcomes were evaluated in 71 right graft living donors. Dominant vs non-dominant MHV anatomy in total liver volume (d-MHV/TLV vs nd-MHV/TLV) was constellated with large/small congestion volumes (CV-index). Small for size (SFS) and non-SFS remnant considerations were based on standard cut-off- RVBWR and RV/TLV. Non-congestive RVBWR was based on non-congestive RV. RESULTS: MHV and non-MHV remnants showed no significant differences in RV, RV/TLV, RVBWR, total bilirubin, or INR. SFS-remnants with RV/TLV < 30% and non-SFS-remnants with RV/TLV ≥ 30% showed no significant differences either. RV and RVBWR for non-MHV (n = 59) and MHV-containing (n = 12) remnants were 550 ± 95 mL and 0.79 ± 0.1 mL vs 568 ± 97 mL and 0.79 ± 0.13, respectively (P = 0.423 and P = 0.919. Mean left RV/TLV was 35.8% ± 3.9%. Non-MHV (n = 59) and MHV-containing (n = 12) remnants (34.1% ± 3% vs 36% ± 4% respectively, P = 0.148. Eight SFS-remnants with RVBWR < 0.65 had a significantly smaller RV/TLV than 63 non-SFS-remnants with RVBWR ≥ 0.65 [SFS: RV/TLV 32.4% (range: 28%-35.7%) vs non-SFS: RV/TLV 36.2% (range: 26.1%-45.5%), P < 0.009. Six SFS-remnants with RV/TLV < 30% had significantly smaller RVBWR than 65 non-SFS-remnants with RV/TLV ≥ 30% (0.65 (range: 0.6-0.7) vs 0.8 (range: 0.6-1.27), P < 0.01. Two (2.8%) donors developed reversible liver failure. RVBWR and RV/TLV were concordant in 25%-33% of SFS and in 92%-94% of non-SFS remnants. MHV management options including complete MHV vs MHV-4A selective retention were necessary in n = 12 vs n = 2 remnants

  10. 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

  11. 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

  12. 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.

  13. Coexistence of mitochondrial DNA and β myosin heavy chain mutations in hypertrophic cardiomyopathy with late congestive heart failure

    PubMed Central

    Arbustini, E; Fasani, R; Morbini, P; Diegoli, M; Grasso, M; Dal, B; Marangoni, E; Banfi, P; Banchieri, N; Bellini, O; Comi, G; Narula, J; Campana, C; Gavazzi, A; Danesino, C; Vigano, M

    1998-01-01

    Objective—To investigate the possible coexistence of mitochondrial DNA (mtDNA) mutations in patients with β myosin heavy chain (βMHC) linked hypertrophic cardiomyopathy (HCM) who develop congestive heart failure.
Design—Molecular analysis of βMHC and mtDNA gene defects in patients with HCM.
Setting—Cardiovascular molecular diagnostic and heart transplantation reference centre in north Italy.
Patients—Four patients with HCM who underwent heart transplantation for end stage heart failure, and after pedigree analysis of 60 relatives, eight additional affected patients and 27 unaffected relatives. A total of 111 unrelated healthy adult volunteers served as controls. Disease controls included an additional 27 patients with HCM and 102 with dilated cardiomyopathy.
Intervention—Molecular analysis of DNA from myocardial and skeletal muscle tissue and from peripheral blood specimens.
Main outcome measures—Screening for mutations in βMHC (exons 3-23) and mtDNA tRNA (n = 22) genes with denaturing gradient gel electrophoresis or single strand conformational polymorphism followed by automated DNA sequencing.
Results—One proband (kindred A) (plus seven affected relatives) had arginine 249 glutamine (Arg249Gln) βMHC and heteroplasmic mtDNA tRNAIle A4300G mutations. Another unrelated patient (kindred B) with sporadic HCM had identical mutations. The remaining two patients (kindred C), a mother and son, had a novel βMHC mutation (lysine 450 glutamic acid) (Lys450Glu) and a heteroplasmic missense (T9957C, phenylalanine (Phe)->leucine (Leu)) mtDNA mutation in subunit III of the cytochrome C oxidase gene. The amount of mutant mtDNA was higher in the myocardium than in skeletal muscle or peripheral blood and in affected patients than in asymptomatic relatives. Mutations were absent in the controls. Pathological and biochemical characteristics of patients with mutations Arg249Gln plus A4300G (kindreds A and B) were identical, but different from

  14. 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.

  15. Decreasing Congestive Heart Failure Readmission Rates Within 30 Days at the Tampa VA.

    PubMed

    Messina, William

    2016-01-01

    High hospital readmission rates contribute to the problem of escalating costs and fragmented quality in the US health care system. This article describes the implementation of a home telehealth (HT) performance improvement project with subsequent cost-avoidance savings. The HT project was designed to potentiate communication between and among patients, clinicians, and administrative staff, in addition to reducing readmissions for patients with congestive heart failure at the James A. Haley Veterans Hospital in Tampa, Florida. Pre- and post-HT implementation comparisons were made of readmission rates, costs, and veteran satisfaction from the same 4-month periods in 2012 and 2013. The application of telehealth and phone care initiatives reduced the congestive heart failure hospital readmission rate by 5%, decreased costs, and improved veteran satisfaction with overall care experience.

  16. 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.

  17. 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.

  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. 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

  20. 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.

  1. 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

  2. [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.

  3. 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.

  4. Gastrointestinal Congestion Dilates the Hepatic Artery Through the P38 MAPK Signal Transduction Pathway During Liver Transplantation.

    PubMed

    Cao, Zhongping; Tang, Xiaowen; Hou, Shike

    2016-01-01

    During the neohepatic stage of liver transplantation, hemodynamics change markedly. The current study aimed to investigate whether gastrointestinal congestion caused by inferior vena cava and hepatic portal vein clamping can dilate the hepatic artery and to determine the associated mechanisms. Ring segments of the hepatic artery were treated with the plasma from gastrointestinal congestion or the superior vena cava. The fractions in gastrointestinal congestion and the superior vena cava plasma were tested, and the effect of these fractions on the tone of the hepatic artery ring was examined. Different signal transduction blockers and different inhibitors were then used to determine the exact signal transduction pathway involved. In addition, endothelial cell structure was observed by transmission electron microscopy after treatment with the gastrointestinal congestion plasma or the superior vena cava plasma. Gastrointestinal congestion plasma contained more inflammatory cytokines than superior vena cava plasma, and these cytokines could cause hepatic artery ring dilatation. A P38 mitogen-activated protein kinase (P38 MAPK) signal transduction pathway blocker and nitric oxide (NO), prostaglandin (PGI2), nuclear factor-κB (NF-κB), and adenosine triphosphate (ATP)-sensitive K (KATP) channel inhibitors were able to significantly reverse the ring tension caused by gastrointestinal congestion plasma. The normal endothelium was also injured by treatment with gastrointestinal congestion plasma. The inflammatory cytokines in gastrointestinal congestion can cause hepatic artery ring dilatation through the P38 MAPK signal transduction pathway, and this phenomenon is also associated with NO, PGI2, NF-κB, and the KATP channel. These inflammatory cytokines can injure endothelial cells in the hepatic artery. PMID:26955003

  5. 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

  6. [Influence of amlodipine on serum level of some cytokines in patients with congestive heart failure].

    PubMed

    Salomon, Piotr; Halawa, Bogumił; Karolko, Bozena

    2003-02-01

    Recent studies showed higher plasma levels of several cytokines, such as interleukines or tumour necrosis factor in patients with congestive heart failure. Cytokines play a very important role in pathogenesis of congestive heart failure, because they impair contractility of heart muscle and cause damage of endothelium and myocytes due to their proinflammatory effects. One of the treatment modalities of heart failure might be administration of drugs inhibiting production of cytokines. The study was undertaken to evaluate whether beneficial effects of amlodipine in congestive heart failure are due to inhibition of synthesis of cytokines. The plasma levels of interleukine 6 (IL-6), tumour necrosis factor (TNF-alpha), neuropeptide Y (NPY) and endothelin-1 (ET-1) were determined in patients with congestive heart failure (NYHA II and III) before and after 30 days of treatment with amlodipine. 40 patients with congestive heart failure (CHF) treated in the Department of Cardiology of Medical University in Wrocław participated in this study. In all patients CHF developed in the course of ischaemic heart disease and coexisting hypertension. Patients were divided into 2 groups dependingly on the NYHA classification. The first group consisted of 24 patients in II NYHA class, the other one--of 16 patients in III NYHA class. At 8 am, on the second day after admission and before treatment with amlodipine blood samples were taken from examined patients to determine plasma levels of IL-6, TNF-alpha, NPY and ET-1. Then patients were administered amlodipine at the dose of 5-10 mg per day. The next blood samples were taken on 5th and 30th day of treatment. Plasma levels of TNF-alpha, IL-6, NPY and ET-1 were estimated with radioimmunoassay using Medgerix kits. Our findings showed that plasma levels of TNF-alpha, IL-6, NPY and ET-1 in patients with CHF are increased. 30-days treatment with amlodipine caused significant decrease of TNF-alpha and IL-6 levels, but did not influence the

  7. Meningeal haemorrhage and congestion associated with the perinatal mortality of beef calves.

    PubMed

    Haughey, K G

    1975-01-01

    Thirty Angus, Hereford and Shorthorn term calves dying before, during or within 7 days of birth in a large beef herd were autopsied. Selected specimens were examined histologically. Two carcasses were classified in the category of ante-parturient death, 24 as parturient, and 4 were classified in the post-parturient death category. Three of the latter showed evidence of starvation. Eight of the calves in the parturient death category were assisted during delivery, and 16 were not assisted. The incidence of nulliparous dams among assisted parturient deaths was significantly higher than among the unassisted group. A high incidence of meningeal haemorrhages and congestion were observed at single or multiple sites, within and around the cranial and spinal meninges. The lesions comprised subdural and epidural haemorrhages, bloodstained cerebrospinal fluid and leptomeningeal haemorrhage and congestion. They were seen in calves in both parturient and post-parturient death categories but not in the ante-parturient group. All calves classified in the parturient death category which were assisted during delivery showed haemorrhages involving the cranial and/or spinal meninges. Additional birth injuries, including separation of the costo-chondral junctions, fractured ribs, haemorrhage into the hip joints, inter-vertebral fibrocartilages and axillae, and rupture of the liver, were frequently present. Ten of the calves in the parturient death category which were unassisted during delivery showed meningeal haemorrhage and congestion. Two of the 4 calves in the post-parturient death category showed similar lesions and both showed evidence of starvation. The meningeal haemorrhages and congestion were similar to those observed in perinatal lamb mortality. They are considered manifestations of injury to the CNS arising from trauma and/or hypoxia during birth. Gross or microscopic evidence of infection was present in 2 calves in the post-parturient death category. Calves which had

  8. 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.

  9. 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.

  10. Cycle-by-cycle analysis of congested flow at signalized intersections

    SciTech Connect

    Rouphail, N.M. )

    1991-03-01

    The increasing number of traffic signals and traffic signal systems in urban areas in the United States is influencing traffic-flow patterns on roadways. Because of the closer proximity of traffic signals (whether coordinated or not), there are fewer observed variations in traffic flow demand during peak hour, and fewer signals in urban areas now operate in truly isolated mode. This is especially true in the case of heavy demand volumes where upstream signals tend to filter traffic at the signal capacity (that is, at virtually a fixed rate). From the traffic engineer's standpoint, the issues associated with congested flow are quite different from those occurring under normal operation (some would even argue that congestion of gridlock is now considered normal operation). The following questions may be asked: How long will it take to clear the congestion developed during peak period; What maximum overflow queue can be expected; How much improvement can be achieved through better signal coordination The principal tool available to traffic engineers for the analysis of signalized intersections in the United States is the {ital Highway Capacity Manual} (HCM). Yet, none of the issues mentioned above is adequately addressed in the HCM. For example, the HCM method uses a fixed peak period of analysis of 15 minutes for calculating level of service. The HCM method has no mechanism for estimating queues, or for estimating when peak-period queues can be cleared on an approach. Furthermore, signal coordination effects are expressed by a set of progression factors that have a very loose correspondence to signal offsets. More important, all analyses in the 1985 HCM are performed assuming average conditions in 15-minute peak period without considering the cycle-by-cycle variation in flows, queues, and delays. Finally, the level-of-service analysis is limited to situations with no initial queue at the start of the peak period and to volume-to-capacity ratios under 1.20.

  11. 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.

  12. 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.

  13. A Rate Feedback Predictive Control Scheme Based on Neural Network and Control Theory for Autonomic Communication

    NASA Astrophysics Data System (ADS)

    Xiong, Naixue; Vasilakos, Athanasios V.; Yang, Laurence T.; Long, Fei; Shu, Lei; Li, Yingshu

    The main difficulty arising in designing an efficient congestion control scheme lies in the large propagation delay in data transfer which usually leads to a mismatch between the network resources and the amount of admitted traffic. To attack this problem, this chapter describes a novel congestion control scheme that is based on a Back Propagation (BP) neural network technique.We consider a general computer communication model with multiple sources and one destination node. The dynamic buffer occupancy of the bottleneck node is predicted and controlled by using a BP neural network. The controlled best-effort traffic of the sources uses the bandwidth, which is left over by the guaranteed traffic. This control mechanism is shown to be able to avoid network congestion efficiently and to optimize the transfer performance both by the theoretic analyzing procedures and by the simulation studies.

  14. 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

  15. Congestive Hepatomegaly

    MedlinePlus

    ... Search Drug Interactions Pill Identifier Commonly searched drugs Aspirin Metformin Warfarin Tramadol Lactulose Ranitidine News & Commentary Recent News Cancer Caregivers Face Difficult Demands Child Health Improves When ...

  16. 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.

  17. Venus' nighttime horizontal plasma flow, 'magnetic congestion', and ionospheric hole production

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Mayr, H. G.; Curtis, S. A.; Taylor, H. A., Jr.

    1983-01-01

    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.

  18. The economic impact of Medicare Part D on congestive heart failure.

    PubMed

    Dall, Timothy M; Blanchard, Tericke D; Gallo, Paul D; Semilla, April P

    2013-05-01

    Medicare Part D has had important implications for patient outcomes and treatment costs among beneficiaries with congestive heart failure (CHF). This study finds that improved medication adherence associated with expansion of drug coverage under Part D led to nearly $2.6 billion in reductions in medical expenditures annually among beneficiaries diagnosed with CHF and without prior comprehensive drug coverage, of which over $2.3 billion was savings to Medicare. Further improvements in adherence could potentially save Medicare another $1.9 billion annually, generating upwards of $22.4 billion in federal savings over 10 years. PMID:23725537

  19. Should All Congestive Heart Failure Patients Have a Routine Sleep Apnea Screening? Con

    PubMed Central

    Li, Yanru; Daniels, Lori B.; Strollo, Patrick J.; Malhotra, Atul

    2015-01-01

    Sleep-disordered breathing (SDB) is one of the most common comorbidities in people with congestive heart failure (CHF). Although SDB has major cardiometabolic consequences, the attributable risk of SDB in asymptomatic CHF patients remains unclear. Whether early intervention using positive airway pressure would improve the prognosis in CHF patients is uncertain. As yet, there is insufficient evidence that routine polysomnography screening is cost-effective for asymptomatic CHF patients. Careful clinical risk evaluation and thoughtful use of limited-channel home sleep testing should be considered before the application of routine polysomnography in all CHF patients. PMID:26112304

  20. 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

  1. Laparoscopic transperitoneal gonadal vein ligation for treatment of pelvic congestion secondary to Nutcracker syndrome: a case report.

    PubMed

    Viriyaroj, Vichit; Akranurakkul, Prinya; Muyphuag, Bunlung; Kitporntheranunt, Maethaphan

    2012-12-01

    Nutcracker syndrome is the term used to describe the patient with clinical symptoms of entrapment of the left renal vein between the aorta and the superior mesenteric artery. Pelvic congestion syndrome, which is a cause of chronic pelvic pain in women, may be due to Nutcracker syndrome. There are many modalities of treatment for Nutcracker syndrome. This is a case report of a 32-year old woman with pelvic congestion syndrome due to Nutcracker syndrome, who subsequently underwent laparoscopic transperitoneal left gonadal vein ligation. She has had complete remission of pain in 4 months after the operation and after 12 months of follow-up. Laparoscopic transperitoneal gonadal vein ligation is an approach that is safe, simple and provides good results for patient with pelvic congestion syndrome secondary to Nutcracker syndrome.

  2. 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. PMID:27543478

  3. 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.

  4. [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.

  5. Endocardiosis and congestive heart failure in a captive ostrich (Struthio camelus).

    PubMed

    Kubba, M A G; Al-Azreg, S A

    2013-01-01

    A seven-year-old blue-necked male ostrich was found dead after a few days of illness. The animal was living in an open yard of 25 square meters along with three other females. They were given concentrate-rich ration with free access to green leaves and water. Autopsy revealed cardiac enlargement due to left ventricular hypertrophy and right ventricular dilatation. The left aterioventricular valves were irregularly thickened and contracted. The lungs were engorged with blood and the liver had nutmeg appearance. The small intestine showed segmental sub-serosal petechial hemorrhages. Histological examination revealed myxomatous degeneration of the left aterioventricular valves, pulmonary congestion and edema, congestion of periacinar hepatic zone and fatty degeneration of outer zones, renal glomerulosclerosis and arteriosclerosis. The affected parts of the small intestine showed villous atrophy with lacteal distention. The venules in the affected intestinal segment were severely dilated while the arterioles had narrow lumen and irregular wall thickening with hyaline deposition. The current article reports an endocardiosis in ostrich and discusses other vascular disorders.

  6. Patient Medication Adherence and Physician Prescribing among Congestive Heart Failure Patients of Yemen.

    PubMed

    Alakhali, K M; Daniel, P S; Noohu, A M; Sirajudeen, S A

    2013-09-01

    Congestive heart failure has been associated with high morbidity and mortality requiring hospitalisation and is further complicated by noncompliance and under prescriptions. We aim to determine medication adherence and percentage deviation among Asians population in general and Yemenis in particular. A cross-sectional, prospective observational study with purposive sampling was conducted at two cardiac outpatient centers in 70 congestive heart failure patients for a period of 3 months. An Arabic translated Morisky 4 item scale assessed the adherence of patients. Deviation in prescribing was determined by chart review. All 70 patients had mean age of 56.6±16 years. Morisky 4 item scale predicted low adherence (n=33; 47.1%) and overall nonadherencerate (n=38; 54.2%) was slightly higher than adherence. Percentage nonadherence versus adherence was high with diuretics (53 vs. 46%) and, digoxin (40 vs. 29%). The adherence percentage of angiotensin receptor blockers (9%) and beta blockers (8%) was low. Diuretics were the most prescribed drugs (n=69; 99%), followed by angiotensin converting enzyme inhibitors (n=51; 73%), cardiac glycoside (n=48; 69%), few patients were on angiotensin receptor blockers (n=8; 11%) and (n=9; 13%) beta blockers. The maximum prescribing rate deviation was seen with angiotensin receptor blockers (-89%) and beta blockers (-87%) followed by nitrates (-77%). Digoxin (-31%) and angiotensin converting enzymes (-27%) deviated comparatively less. Prescribing as well as utilisation rates generally were low resulting in nonachievement of therapeutic goals which could be resolved using multimodel approach. PMID:24403656

  7. Infantile Hepatic Hemangioendothelioma Associated With Congestive Heart Failure: Two Case Reports With Different Outcomes.

    PubMed

    Wang, Tao; Wang, Yibin; Liang, Yun; Lu, Guoyan

    2015-12-01

    Infantile hepatic hemangioendothelioma (IHH) is rare which can regress spontaneously. Arteriovenous shunts within hemangiomas, however, may result in pulmonary artery hypertension (PAH) and congestive heart failure (CHF).The authors report 2 young infants suffering from multifocal IHH associated with CHF were both treated with glucocorticoid and transcatheter arterial embolization (TAE), but had different outcomes. The PAH decreased immediately and the symptoms of CHF were alleviated after TAE for both of them. For the Tibetan infant, the development was normal with tumor regression by follow-up. For the Han ethnic neonate, PAH increased again in the seventh day with progressive cardiovascular insufficiency. Ultrasound showed a persisting perfusion caused by collateralization around occluded main feeders. Furthermore, a pulmonary infection occurred and ventilation was performed. As a result, the infant died from multiorgan failure caused by CHF and infection.TAE is a treatment of reducing shunting for hemangiomas. Fistula recanalization in multifocal IHH, however, might be an important risk factor affecting the outcome of TAE. TAE should be further evaluated with special attention to anatomy of feeding and draining vessels, and cardiopulmonary conditions. In addition, the patients were susceptible to secondary pulmonary infection because of lung congestion. As well, the infant from the high altitude area showed better adaptability to hypoxia.

  8. 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.

  9. Nature of the Congested Traffic and Quasi-steady States of the General Motor Models

    NASA Astrophysics Data System (ADS)

    Yang, Bo; Xu, Xihua; Pang, John Z. F.; Monterola, Christopher

    2015-03-01

    We look at the general motor (GM) class microscopic traffic models and analyze some of the universal features of the (multi-)cluster solutions, including the emergence of an intrinsic scale and the quasisoliton dynamics. We show that the GM models can capture the essential physics of the real traffic dynamics, especially the phase transition from the free flow to the congested phase, from which the wide moving jams emerges (the F-S-J transition pioneered by B.S. Kerner). In particular, the congested phase can be associated with either the multi-cluster quasi-steady states, or their more homogeneous precursor states. In both cases the states can last for a long time, and the narrow clusters will eventually grow and merge, leading to the formation of the wide moving jams. We present a general method to fit the empirical parameters so that both quantitative and qualitative macroscopic empirical features can be reproduced with a minimal GM model. We present numerical results for the traffic dynamics both with and without the bottleneck, including various types of spontaneous and induced ``synchronized flow,'' as well as the evolution of wide moving jams. We also discuss its implications to the nature of different phases in traffic dynamics.

  10. [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)

  11. 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.

  12. The impact of congestion charging on vehicle speed and its implications for assessing vehicle emissions

    NASA Astrophysics Data System (ADS)

    Beevers, Sean D.; Carslaw, David C.

    Previous analysis of London's congestion charging scheme (CCS) has shown that changes in vehicle speed are an important factor in reducing vehicle emissions. Therefore, a detailed investigation of network average vehicle speed in both central and inner London has been undertaken using a combination of the non-parametric Wilcoxon sign ranks test and a method for calculating the cumulative difference between mean speeds pre- and post-CCS, or cumulative sum (CUSUM) analysis. Within the charging zone (CZ), the Wilcoxon test has shown that the difference in speed between pre- and post-CCS periods has increased on average by 2.1 km h -1 and that these changes are significant at the p=0.05 level. The CUSUM analysis has provided evidence of the timing of this change in mean speed in the CZ and this agrees well with the introduction of the CCS on the 17 February 2003. In combination, these results provide compelling evidence that the introduction of congestion charging has significantly increased vehicle speed in the CZ and by comparison with the results in inner London, that these changes are not part of a wider trend. To examine one impact of this change we used an instantaneous emissions model, the Vehicle Transient Emissions Simulation Software, to undertake a comparison between the change in vehicle emissions associated with changing driving characteristics, between pre- and post-charging periods, and those associated with a change in average speed. The analysis was limited to three vehicle types: a Euro II LGV, a Euro III diesel car and a Euro IV petrol car, but showed that driving characteristics in central London have a relatively small effect on emissions of NO X and CO 2 compared with the average vehicle speed. However, for PM 10 emissions from the Euro II LGV the opposite was found and for this vehicle the driving characteristics were more important than the average speed in estimating exhaust emissions. For this vehicle, emissions increased between pre- and post

  13. Effect of Back Massage Intervention on Anxiety, Comfort, and Physiologic Responses in Patients with Congestive Heart Failure

    PubMed Central

    Chen, Wei-Ling; Liu, Gin-Jen; Chiang, Ming-Chu; Fu, Mao-Young; Hsieh, Yuan-Kai

    2013-01-01

    Abstract Background Patients suffering from congestive heart failure (CHF) frequently feel physical suffering and anxiety. Objectives The researchers investigated whether back massage could reduce anxiety, discomfort, and physical suffering in patients with CHF. The effects of gender and severity-dependent response of back massage on anxiety and discomfort in patients were also analyzed. Design The study used a quasi-experimental design with one group pretest and posttest. Participants Sixty-four participants were recruited in southern Taiwan. Outcome measures The modified State Anxiety Inventory, the discomfort Visual Analogue Scale, electronic blood pressure (BP) gauges, stethoscopes and the pulse oximetry were used in this study. Results The participants' systolic BP (F (3, 189)=18.91, p<0.01), diastolic BP (F (3, 189)=13.40, p<0.01), heart rate (F (3, 189)=26.28, p<0.01), and respiratory rates (F (3, 189)=5.77, p<0.01) were significantly decreased after back massage. Oxygen saturation levels showed significant increases (F (3, 189)=42.82, p<0.01). Male participants revealed a more significant reduction in anxiety than the female participants (F (1, 50)=7.27, p=0.01). Those with more severe heart failure and greater levels of anxiety (F (2, 61)=4.31, p=0.02) and systolic BP (F (2, 61)=3.86, p=0.03) demonstrated significantly greater responses to back massage. Conclusions Back massage significantly reduced anxiety in the study population. Systolic BP decreased to a greater degree in the male participants, particularly in those with severe heart failure and greater levels of anxiety and higher systolic BP. This study was conducted without a control group. Randomized clinical trials are needed to validate the effectiveness of back massage on patients with CHF. PMID:23186129

  14. 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).

  15. A case of juvenile acromegaly that was initially diagnosed as severe congestive heart failure from acromegaly-induced dilated cardiomyopathy.

    PubMed

    Sue, Mariko; Yoshihara, Aya; Okubo, Yoichiro; Ishikawa, Mayumi; Ando, Yasuyo; Hiroi, Naoki; Shibuya, Kazutoshi; Yoshino, Gen

    2010-01-01

    Acromegaly is characterized by chronic hypersecretion of growth hormone (GH) and is associated with increased mortality rate because of the potential complications such as cardiovascular disease, respiratory disease, or malignancy, which are probably caused by the long-term exposure of tissues to excess GH, for at least 10 years, before diagnosis and treatment. A 22-year-old man with a 2-month history of fatigue was admitted to our hospital because of chest discomfort, dyspnea, and pitting edema of the lower limbs experienced over a 1-month period. On admission, his height and body weight were 186 cm and 138.5 kg, respectively, with a BMI of 39.8 kg/m(2). He showed acromegalic features and elevated serum GH and IGF-1 levels, which were 11.5 ng/mL and 960 ng/mL, respectively. There was no GH suppression in the 75-g oral glucose tolerance test. Pituitary magnetic resonance imaging (MRI) revealed microadenoma. Chest X-ray revealed cardiomegaly, and echocardiogram showed dilated left ventricular (LV) cavity and diffuse hypokinesis with extremely decreased ejection fraction (EF). He was diagnosed as having acromegaly with congestive heart failure from diastolic cardiomyopathy. After the successful transsphenoidal resection of the pituitary adenoma, the level of GH was normalized. However, the cardiac dysfunction did not show any improvement even after the administration of β-blockers, angiotensin-converting enzyme inhibitor (ACE-I), or diuretics. The patient was re-hospitalized, and he died of cardiac failure at the age of 25 years. Patients with acromegaly have been reported to have about 30% higher mortality rate, and cardiovascular disease accounts for 60% of the deaths. We report a case of a patient with juvenile acromegaly who was diagnosed with severe cardiac failure at the time of diagnosis and failed to recover cardiac function even after the successful resection of the pituitary adenoma. Immediate diagnosis and treatment are required for better control of

  16. 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.

  17. Effect of the Diagnosis of Inflammatory Bowel Disease on Risk-Adjusted Mortality in Hospitalized Patients with Acute Myocardial Infarction, Congestive Heart Failure and Pneumonia

    PubMed Central

    Ehrenpreis, Eli D.; Zhou, Ying; Alexoff, Aimee; Melitas, Constantine

    2016-01-01

    Introduction Measurement of mortality in patients with acute myocardial infarction (AMI), congestive heart failure (CHF) and pneumonia (PN) is a high priority since these are common reasons for hospitalization. However, mortality in patients with inflammatory bowel disease (IBD) that are hospitalized for these common medical conditions is unknown. Methods A retrospective review of the 2005–2011 National Inpatient Sample (NIS), (approximately a 20% sample of discharges from community hospitals) was performed. A dataset for all patients with ICD-9-CM codes for primary diagnosis of acute myocardial infarction, pneumonia or congestive heart failure with a co-diagnosis of IBD, Crohn’s disease (CD) or ulcerative colitis (UC). 1:3 propensity score matching between patients with co-diagnosed disease vs. controls was performed. Continuous variables were compared between IBD and controls. Categorical variables were reported as frequency (percentage) and analyzed by Chi-square tests or Fisher’s exact test for co-diagnosed disease vs. control comparisons. Propensity scores were computed through multivariable logistic regression accounting for demographic and hospital factors. In-hospital mortality between the groups was compared. Results Patients with IBD, CD and UC had improved survival after AMI compared to controls. 94/2280 (4.1%) of patients with IBD and AMI died, compared to 251/5460 (5.5%) of controls, p = 0.01. This represents a 25% improved survival in IBD patients that were hospitalized with AMI. There was a 34% improved survival in patients with CD and AMI. There was a trend toward worsening survival in patients with IBD and CHF. Patients with CD and PN had improved survival compared to controls. 87/3362 (2.59%) patients with CD and PN died, compared to 428/10076 (4.25%) of controls, p < .0001. This represents a 39% improved survival in patients with CD that are hospitalized for PN. Conclusion IBD confers a survival benefit for patients hospitalized with AMI. A

  18. Loss of the eIF2α kinase GCN2 protects mice from pressure overload induced congestive heart failure without affecting ventricular hypertrophy

    PubMed Central

    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

    2016-01-01

    In response to a number of stresses, including nutrient deprivation, General Control Nonderepressible 2 kinase (GCN2) attenuates mRNA translation by phosphorylating eukaryotic initiation factor 2 alpha (eIF2αSer51). Energy starvation is known to exacerbate congestive heart failure (CHF) and eIF2αSer51 phosphorylation is increased in the failing heart. However, the impact of GCN2 during the evolution of CHF 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 (TAC) in Wild Type (WT) and GCN2 knockout (GCN2−/−) mice. Under basal conditions, GCN2−/− had normal LV structure or function but following TAC, demonstrated less contractile dysfunction, less increase of lung weight, less increase of lung inflammation and vascular remodeling, and less myocardial apoptosis and fibrosis compared with WT mice, despite an equivalent degree of LV hypertrophy. As expected, GCN2−/− attenuated TAC induced cardiac eif2αSer51 phosphorylation and preserved Sarcoplasmic reticulum Ca2+ ATPase (Serca2a) expression compared with WT mice. Interestingly, expression of the anti-apoptotic protein Bcl-2 was significantly elevated in GCN2−/− hearts, while 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. PMID:24166753

  19. Atrioventricular Dissociation and Congestive Heart Failure in a Ring-Necked Pheasant ( Phasianus colchicus ).

    PubMed

    Kaya, Mehmet; Gacar, Ayhan; Demirci, Beste; Soylu, Sadettin Mehmet; Gulbahar, Mustafa Yavuz

    2015-06-01

    The aim of this clinical report was to describe a case of complete atrioventricular dissociation in a 9-month-old, male ring-necked pheasant ( Phasianus colchicus ). The case was incidentally determined during the evaluation of electrocardiograms recorded from pheasants. There were no observed clinical symptoms in the bird before or after the electrocardiogram. The PR interval varied, and there was no association of the P waves and QRS complexes in the electrocardiogram. Although the ventricular rhythm was regular (130 beats/min), atrial rhythm was irregular (approximately 91 beats/min). Pathological examination showed there was left ventricular hypertrophy with degeneration of the mitral valve of the heart and well-marked congestion in the liver and lung.

  20. Reducing Congestion in Obstructed Highways with Traffic Data Dissemination Using Ad hoc Vehicular Networks

    NASA Astrophysics Data System (ADS)

    Hewer, Thomas D.; Nekovee, Maziar; Coveney, Peter V.

    2010-12-01

    Vehicle-to-vehicle communications can be used effectively for intelligent transport systems (ITSs) and location-aware services. The ability to disseminate information in an ad hoc fashion allows pertinent information to propagate faster through a network. In the realm of ITS, the ability to spread warning information faster and further is of great advantage to receivers. In this paper we propose and present a message-dissemination procedure that uses vehicular wireless protocols to influence vehicular flow, reducing congestion in road networks. The computational experiments we present show how a car-following model and lane-change algorithm can be adapted to "react" to the reception of information. This model also illustrates the advantages of coupling together with vehicular flow modelling tools and network simulation tools.

  1. Pulmonary valvular stenosis complicated by cerebrovascular accident and congestive heart failure in a young child.

    PubMed

    Chu, Y T; Liang, C D; Ko, S F; Huang, S C; Tiao, M M

    2001-08-01

    Pulmonary valvular stenosis (PS) with intact ventricular septum is a common congenital heart disease. In general, mild PS has a benign clinical course. However, in severe PS and some cases of moderate stenosis, increasing severity of the lesion may occur. The manifestations of either cerebrovascular accident (CVA) or congestive heart failure (CHF) are rarely reported in pediatric patients with PS. In this report, we describe a girl with severe PS complicated by seizures and sudden onset of hemiparesis at 13 months of age who developed CHF when 16 months old. CHF was cured after successful balloon valvuloplasty. She remained well without residual hemiparesis or recurrent seizures during the 1-year follow-up. Early balloon valvuloplasty should be emphasized in patients with severe PS, even if there are no significant clinical symptoms. With prompt balloon valvuloplasty, these complications can be effectively prevented.

  2. Acute haemodynamic effects of ibopamine in patients with severe congestive heart failure.

    PubMed Central

    Ghirardi, P; Brusoni, B; Mangiavacchi, M; Bianco, L; Col, J; Metra, M; Dei Cas, L

    1985-01-01

    Ten patients with congestive heart failure (CHF), in III and IV NYHA Class, were treated orally with a single dose of ibopamine ranging from 1.2-3.3 mg/kg, and were studied using the Swan-Ganz catheter and thermodilution technique. Cardiac index (CI) and stroke volume index (SVI) were increased, and mean pulmonary pressure (PAP), systemic vascular resistances (SVR) were lowered. Ibopamine increased CI (+33%) and SVI (+26%), and decreased PAP (-17%) and SVR (-24%). All changes were statistically significant. The maximum haemodynamic effect occurred 180 min after ibopamine administration. Blood pressure and heart rate were unaffected. Tolerability was good. This study shows that ibopamine when orally administered to human subjects improves cardiac performance and further investigations on its use as a therapeutic agent in the long term treatment of CHF are recommended. PMID:4005102

  3. Effect of Cardiac Resynchronization Therapy on Inflammation in Congestive Heart Failure: A Review.

    PubMed

    Lappegård, K T; Bjørnstad, H; Mollnes, T E; Hovland, A

    2015-09-01

    Congestive heart failure is associated with increased levels of several inflammatory mediators, and animal studies have shown that infusion of a number of cytokines can induce heart failure. However, several drugs with proven efficacy in heart failure have failed to affect inflammatory mediators, and anti-inflammatory therapy in heart failure patients has thus far been disappointing. Hence, to what extent heart failure is caused by or responsible for the increased inflammatory burden in the patient is still unclear. Over the past couple of decades, resynchronization therapy with a biventricular pacemaker has emerged as an effective treatment in a subset of heart failure patients, reducing both morbidity and mortality. Such treatment has also been shown to affect the inflammation associated with heart failure. In this study, we review recent data on the association between heart failure and inflammation, and in particular how resynchronization therapy can affect the inflammatory process.

  4. Differential pathways of positive and negative health behavior change in congestive heart failure patients.

    PubMed

    Chaves, Covadonga; Park, Crystal L

    2016-08-01

    This longitudinal study applied a stress and coping model to examine the differential pathways of perceived positive and negative health behavior changes. Participants with congestive heart failure completed self-report measures of psychological resources, coping strategies, and perceived behavior changes and were assessed again 6 months later. Patients with higher positive affect and spiritual well-being reported more positive health behavior changes over time, effects mediated by approach coping. Alternatively, patients with lower psychological resources reported more negative behavior changes over time, effects mediated by avoidance coping. The results suggest that different psychological resources are related to different types of coping which, in turn, are associated with perceived positive or negative changes in health behavior over time.

  5. Macro- and micronutrients in patients with congestive heart failure, particularly African-Americans.

    PubMed

    Newman, Kevin P; Bhattacharya, Syamal K; Munir, Ahmad; Davis, Richard C; Soberman, Judith E; Ramanathan, Kodangudi B

    2007-01-01

    Not all patients with heart failure, defined as a reduced ejection fraction, will have an activation of the RAAS, salt and water retention, or the congestive heart failure (CHF) syndrome. Beyond this cardiorenal perspective, CHF is accompanied by a systemic illness that includes oxidative stress, a proinflammatory phenotype, and a wasting of soft tissues and bone. A dyshomeostasis of calcium, magnesium, zinc, selenium, and vitamin D contribute to the appearance of oxidative stress and to compromised endogenous defenses that combat it. A propensity for hypovitaminosis D, given that melanin is a natural sunscreen, and for secondary hyperparathyroidism in African-Americans make them more susceptible to these systemic manifestations of CHF-a situation which is further threatened by the calcium and magnesium wasting that accompanies the secondary aldosteronism of CHF and the use of loop diuretics. PMID:18078025

  6. Pioglitazone-induced congestive heart failure and pulmonary edema in a patient with preserved ejection fraction.

    PubMed

    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.

  7. 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

  8. Mineralocorticoid receptor antagonists as diuretics: Can congestive heart failure learn from liver failure?

    PubMed

    Masoumi, Amirali; Ortiz, Fernando; Radhakrishnan, Jai; Schrier, Robert W; Colombo, Paolo C

    2015-05-01

    Despite significant improvements in diagnosis, understanding the pathophysiology and management of the patients with acute decompensated heart failure (ADHF), diuretic resistance, yet to be clearly defined, is a major hurdle. Secondary hyperaldosteronism is a pivotal factor in pathogenesis of sodium retention, refractory congestion in heart failure (HF) as well as diuretic resistance. In patients with decompensated cirrhosis who suffer from ascites, similar pathophysiological complications have been recognized. Administration of natriuretic doses of mineralocorticoid receptor antagonists (MRAs) has been well established in management of cirrhotic patients. However, this strategy in patients with ADHF has not been well studied. This article will discuss the potential use of natriuretic doses of MRAs to overcome the secondary hyperaldosteronism as an alternative diuretic regimen in patients with HF.

  9. Mineralocorticoid receptor antagonists as diuretics: Can congestive heart failure learn from liver failure?

    PubMed Central

    Ortiz, Fernando; Radhakrishnan, Jai; Schrier, Robert W.; Colombo, Paolo C.

    2014-01-01

    Despite significant improvements in diagnosis, understanding the pathophysiology and management of the patients with acute decompensated heart failure (ADHF), diuretic resistance, yet to be clearly defined, is a major hurdle. Secondary hyperaldosteronism is a pivotal factor in pathogenesis of sodium retention, refractory congestion in heart failure (HF) as well as diuretic resistance. In patients with decompensated cirrhosis who suffer from ascites, similar pathophysiological complications have been recognized. Administration of natriuretic doses of mineralocorticoid receptor antagonists (MRAs) has been well established in management of cirrhotic patients. However, this strategy in patients with ADHF has not been well studied. This article will discuss the potential use of natriuretic doses of MRAs to overcome the secondary hyperaldosteronism as an alternative diuretic regimen in patients with HF. PMID:25447845

  10. Pearls and pitfalls in the use and abuse of diuretics for chronic congestive heart failure.

    PubMed

    Constant, J

    1999-01-01

    The main purpose of using diuretics is usually lost sight of, i.e. it is for the relief of dyspnea by using the least amount of a diuretic. The production of a low output state and hypercoagulation in an attempt to achieve dry weight by lowering blood volume excessively are among the hazards of using more diuretic than is absolutely necessary to achieve the goal of relieving dyspnea. The use of jugular venous pressure measurement and the status of dyspnea should have precedence over body weight in determining diuretic dose adjustment. Often forgotten in using diuretics is that potassium without magnesium will not enter cells and that the almost universal preference for furosemide over thiazides threatens to increase the incidence of osteoporosis. Also, the tendency to ignore loss of the water-soluble vitamins thiamine and ascorbic acid may result in refractory edema and the inability to manage the stresses of congestive heart failure.

  11. [CorBene: a new model for collaborative care of patients with congestive heart failure].

    PubMed

    Gysan, D B; Albus, C; Riedel, R; Hossmann, V; Vogt, A; Latz, V; Griebenow, R

    2012-02-01

    Congestive heart failure (CHF) is one of the most common medical disorders. The prognosis tends to be unfavorable and the quality of care needs further improvement. The aim of the CorBene project is to improve the health-related quality of life and the prognosis in patients in all stages of CHF and to reduce the hospitalization rate. For this purpose a modern collaborative treatment program involving all relevant health care professionals was developed. The key feature is the close collaboration between family physicians, practicing cardiologists, hospitals and rehabilitation facilities. The CorBene model was launched in Cologne and then spread to North-Rhine/Westphalia and to Saarland. Currently, there is the possibility to offer it in all German states. Preliminary analyses confirm an optimal, guideline-based therapy of CHF. PMID:22252271

  12. The Effect of Age upon Care and Outcomes in Patients Hospitalized for Congestive Heart Failure in Alberta, Canada

    ERIC Educational Resources Information Center

    Cujec, Bibiana; Quan, Hude; Jin, Yan; Johnson, David

    2004-01-01

    We describe the age-specific outcomes for patients hospitalized with newly diagnosed congestive heart failure using administrative hospital abstracts from Alberta, Canada, from April 1, 1994, to March 31, 2000. Seniors (aged 65 years and older) constituted about 85 per cent of the 16,162 patients. Both co-morbidity and severity of illness tended…

  13. Rescue of lip switch flap at risk of necrosis due to venous congestion for cleft lip deformity

    PubMed Central

    Sugiyama, Madoka; Saijo, Hideto; Kazuto, Hoshi; Takato, Tsuyoshi

    2016-01-01

    Abstract In a 21-year-old male with bilateral cleft lip who developed marked venous congestion of a lip switch flap, we returned the grafted flap to the donor site to improve blood circulation of the flap and then re-transplanted it, which prevented flap necrosis. Here, we report the procedure and case. PMID:27583269

  14. Rescue of lip switch flap at risk of necrosis due to venous congestion for cleft lip deformity.

    PubMed

    Sugiyama, Madoka; Saijo, Hideto; Kazuto, Hoshi; Takato, Tsuyoshi

    2016-01-01

    In a 21-year-old male with bilateral cleft lip who developed marked venous congestion of a lip switch flap, we returned the grafted flap to the donor site to improve blood circulation of the flap and then re-transplanted it, which prevented flap necrosis. Here, we report the procedure and case. PMID:27583269

  15. When does highway construction to mitigate congestion reduce carbon emissions? A Case Study: The Caldecott Tunnel

    NASA Astrophysics Data System (ADS)

    Thurlow, M. E.; Maness, H.; Wiersema, D. J.; Mcdonald, B. C.; Harley, R.; Fung, I. Y.

    2014-12-01

    The construction of the fourth bore of the Caldecott Tunnel, which connects Oakland and Moraga, CA on State Route 24, was the second largest roadway construction project in California last year with a total cost of $417 million. The objective of the fourth bore was to reduce traffic congestion before the tunnel entrance in the off-peak direction of travel, but the project was a source of conflict between policy makers and environmental and community groups concerned about the air quality and traffic impacts. We analyze the impact of the opening of the fourth bore on CO2 emissions associated with traffic. We made surface observations of CO2from a mobile platform along State Route 24 for several weeks in November 2013 incorporating the period prior to and after the opening of the fourth bore on November 16, 2013. We directly compare bottom-up and top-down approaches to estimate the change in traffic emissions associated with the fourth bore opening. A bottom-up emissions inventory was derived from the high-resolution Performance Measurement System (PeMs) dataset and the Multi-scale Motor Vehicle and Equipment Emissions System (MOVES). The emissions inventory was used to drive a box model as well as a high-resolution regional transport model (the Weather and Regional Forecasting Model). The box model was also used to derive emissions from observations in a basic inversion. We also present an analysis of long-term traffic patterns and consider the potential for compensating changes in behavior that offset the observed emissions reductions on longer timescales. Finally, we examine how the results from the Caldecott study demonstrate the general benefit of using mobile measurements for quantifying environmental impacts of congestion mitigation projects.

  16. Characterizing Longitude-Dependent Orbital Debris Congestion in the Geosynchronous Orbit Regime

    NASA Astrophysics Data System (ADS)

    Anderson, Paul V.

    The geosynchronous orbit (GEO) is a unique commodity of the satellite industry that is becoming increasingly contaminated with orbital debris, but is heavily populated with high-value assets from the civil, commercial, and defense sectors. The GEO arena is home to hundreds of communications, data transmission, and intelligence satellites collectively insured for an estimated 18.3 billion USD. As the lack of natural cleansing mechanisms at the GEO altitude renders the lifetimes of GEO debris essentially infinite, conjunction and risk assessment must be performed to safeguard operational assets from debris collisions. In this thesis, longitude-dependent debris congestion is characterized by predicting the number of near-miss events per day for every longitude slot at GEO, using custom debris propagation tools and a torus intersection metric. Near-miss events with the present-day debris population are assigned risk levels based on GEO-relative position and speed, and this risk information is used to prioritize the population for debris removal target selection. Long-term projections of debris growth under nominal launch traffic, mitigation practices, and fragmentation events are also discussed, and latitudinal synchronization of the GEO debris population is explained via node variations arising from luni-solar gravity. In addition to characterizing localized debris congestion in the GEO ring, this thesis further investigates the conjunction risk to operational satellites or debris removal systems applying low-thrust propulsion to raise orbit altitude at end-of-life to a super-synchronous disposal orbit. Conjunction risks as a function of thrust level, miss distance, longitude, and semi-major axis are evaluated, and a guidance method for evading conjuncting debris with continuous thrust by means of a thrust heading change via single-shooting is developed.

  17. Radiographic and echocardiographic assessment of left atrial size in 100 cats with acute left-sided congestive heart failure.

    PubMed

    Schober, Karsten E; Wetli, Ellen; Drost, Wm Tod

    2014-01-01

    The aims of this study were to evaluate left atrial size in cats with acute left-sided congestive heart failure. We hypothesized that left atrial size as determined by thoracic radiography can be normal in cats with acute left-sided congestive heart failure. One hundred cats with acute left-sided congestive heart failure in which thoracic radiography and echocardiography were performed within 12 h were identified. Left atrial size was evaluated using right lateral and ventrodorsal radiographs. Measurements were compared to two-dimensional echocardiographic variables of left atrial size and left ventricular size. On echocardiography, left atrial enlargement was observed in 96% cats (subjective assessment) whereas maximum left atrial dimension was increased (>15.7 mm) in 93% cats. On radiographs left atrial enlargement (subjective assessment) was found in 48% (lateral view), 53% (ventrodorsal view), and 64% (any view) of cats whereas left atrial enlargement was absent in 36% of cats in both views. Agreement between both methods of left atrial size estimation was poor (Cohen's kappa 0.17). Receiver operating characteristic curve analysis identified a maximum echocardiographic left atrial dimension of approximately 20 mm as the best compromise (Youden index) between sensitivity and specificity in the prediction of radiographic left atrial enlargement. Left atrial enlargement as assessed by thoracic radiography may be absent in a clinically relevant number of cats with congestive heart failure. Therefore, normal left atrial size on thoracic radiographs does not rule out presence of left-sided congestive heart failure in cats with clinical signs of respiratory distress.

  18. The control method for the lattice hydrodynamic model

    NASA Astrophysics Data System (ADS)

    Ge, Hong-Xia; Cui, Yu; Zhu, Ke-Qiang; Cheng, Rong-Jun

    2015-05-01

    The delayed-feedback control method is applied for lattice hydrodynamic model of traffic flow. The linear stability condition with and without control signal are derived through linear and nonlinear analysis. Numerical simulation is carried out and the results confirm that the traffic congested can be suppressed efficiently by considering the control signal.

  19. Adaptive Transmission Control Method for Communication-Broadcasting Integrated Services

    NASA Astrophysics Data System (ADS)

    Koto, Hideyuki; Furuya, Hiroki; Nakamura, Hajime

    This paper proposes an adaptive transmission control method for massive and intensive telecommunication traffic generated by communication-broadcasting integrated services. The proposed method adaptively controls data transmissions from viewers depending on the congestion states, so that severe congestion can be effectively avoided. Furthermore, it utilizes the broadcasting channel which is not only scalable, but also reliable for controlling the responses from vast numbers of viewers. The performance of the proposed method is evaluated through experiments on a test bed where approximately one million viewers are emulated. The obtained results quantitatively demonstrate the performance of the proposed method and its effectiveness under massive and intensive traffic conditions.

  20. Voiding dysfunction in patients with nasal congestion treated with pseudoephedrine: a prospective study

    PubMed Central

    Shao, I-Hung; Wu, Chia-Chen; Tseng, Hsiao-Jung; Lee, Ta-Jen; Lin, Yu-Hsiang; Tam, Yuan-Yun

    2016-01-01

    Background Pseudoephedrine is a sympathomimetic drug widely used as a nasal decongestant. However, it can cause adverse effects, such as voiding dysfunction. The risk of voiding dysfunction remains uncertain in patients without subjective voiding problems. Methodology We prospectively enrolled patients with nasal congestion who required treatment with pseudoephedrine from May to August 2015. All patients denied concomitant subjective voiding problem. The International Prostate Symptom Score (IPSS) questionnaire was used to evaluate voiding function before and 1 week after the pseudoephedrine treatment. The results of the IPSS questionnaire were analyzed as the total (IPSS-T), voiding (IPSS-V), storage (IPSS-S), and quality of life due to urinary symptom scores. Results We enrolled 131 males with a mean age of 42.0±14.3 years. The IPSS-T, IPSS-V, and IPSS-S scores slightly increased after the medication (IPSS-T increased from 6.49 to 6.77, IPSS-V from 3.33 to 3.53, and IPSS-S from 3.17 to 3.24). The quality of life due to urinary symptom score nonsignificantly decreased from 2.02 to 1.87. We observed that older age and a higher premedication IPSS-V score yielded significant differences (P<0.05) for subclinical voiding dysfunction and unchanged voiding function. In patients aged ≥50 years, the IPSS-T, IPSS-V, and IPSS-S scores significantly increased after the pseudoephedrine treatment (IPSS-T increased from 9.95 to 11.45, IPSS-V from 5.38 to 6.07, and IPSS-S 4.57 to 5.38), whereas the quality of life due to urinary symptom score nonsignificantly decreased from 2.71 to 2.48 (P=0.057). In patients aged <50 years, all scores did not significantly differ. Conclusion Pseudoephedrine treatment for nasal congestion requires extra precautions in males >50 years, even without subjective voiding symptoms. PMID:27486310

  1. Cap-and-Trade Modeling and Analysis: Congested Electricity Market Equilibrium

    NASA Astrophysics Data System (ADS)

    Limpaitoon, Tanachai

    analysis of the joint markets in the presence of market power reveals that strategic permit trading can play a vital role in determining economic outcomes in the electricity market. In particular, I find that a firm with more efficient technologies can employ strategic withholding of permits, which allows for its increase in output share in the electricity market at the expense of other less efficient firms. In addition, strategic permit trading can influence patterns of transmission congestion. These results illustrate that market structure and transmission congestion can have a significant impact on the market performance and environmental outcome of the regulation while the interactions of such factors can lead to unintended consequences. The proposed approach is proven useful as a tool for market monitoring purposes in the short run from the perspective of a system operator, whose responsibility has become indirectly intertwined with emission trading regulation.

  2. Thyrotropin-secreting pituitary tumor presenting with congestive heart failure and good response to dopaminergic agonist cabergoline.

    PubMed

    Kao, Yu-Hsi; Chang, Tien-Jyun; Huang, Tien-Shang

    2013-11-01

    Hyperthyroidism is an important inducing factor in patients with atrial fibrillation, and may trigger heart failure. Thyrotropin (thyroid stimulating hormone, TSH)-secreting pituitary tumors are rare causes of hyperthyroidism. Here, we report a 66-year-old man with a pituitary TSH-secreting tumor who presented with hyperthyroidism and congestive heart failure. Endonasal trans-sphenoidal pituitary adenomectomy was performed. After the operation, the symptoms of hyperthyroidism and congestive heart failure were relieved, associated with normalization of thyroid function tests. Unfortunately, hand tremor and progressively elevated free T4 and TSH concentrations recurred 5 months after surgery. A dopaminergic agonist, cabergoline was administered and euthyroidism was restored for at least 11 months.

  3. Acromegaly with Normal Insulin-Like Growth Factor-1 Levels and Congestive Heart Failure as the First Clinical Manifestation.

    PubMed

    Lee, Hyae Min; Lee, Sun Hee; Yang, In Ho; Hwang, In Kyoung; Hwang, You Cheol; Ahn, Kyu Jeung; Chung, Ho Yeon; Hwang, Hui Jeong; Jeong, In Kyung

    2015-09-01

    The leading cause of morbidity and mortality in patients with acromegaly is cardiovascular complications. Myocardial exposure to excessive growth hormone can cause ventricular hypertrophy, hypertension, arrhythmia, and diastolic dysfunction. However, congestive heart failure as a result of systolic dysfunction is observed only rarely in patients with acromegaly. Most cases of acromegaly exhibit high levels of serum insulin-like growth factor-1 (IGF-1). Acromegaly with normal IGF-1 levels is rare and difficult to diagnose. Here, we report a rare case of an acromegalic patient whose first clinical manifestation was severe congestive heart failure, despite normal IGF-1 levels. We diagnosed acromegaly using a glucose-loading growth hormone suppression test. Cardiac function and myocardial hypertrophy improved 6 months after transsphenoidal resection of a pituitary adenoma.

  4. On the Existence of Optimal Taxes for Network Congestion Games with Heterogeneous Users

    NASA Astrophysics Data System (ADS)

    Fotakis, Dimitris; Karakostas, George; Kolliopoulos, Stavros G.

    We consider network congestion games in which a finite number of non-cooperative users select paths. The aim is to mitigate the inefficiency caused by the selfish users by introducing taxes on the network edges. A tax vector is strongly (weakly)-optimal if all (at least one of) the equilibria in the resulting game minimize(s) the total latency. The issue of designing optimal tax vectors for selfish routing games has been studied extensively in the literature. We study for the first time taxation for networks with atomic users which have unsplittable traffic demands and are heterogeneous, i.e., have different sensitivities to taxes. On the positive side, we show the existence of weakly-optimal taxes for single-source network games. On the negative side, we show that the cases of homogeneous and heterogeneous users differ sharply as far as the existence of strongly-optimal taxes is concerned: there are parallel-link games with linear latencies and heterogeneous users that do not admit strongly-optimal taxes.

  5. Butyrate protects rat liver against total hepatic ischemia reperfusion injury with bowel congestion.

    PubMed

    Liu, Bin; Qian, Jianmin; Wang, Qingbao; Wang, Fangrui; Ma, Zhenyu; Qiao, Yingli

    2014-01-01

    Hepatic ischemia/reperfusion (I/R) injury is an unavoidable consequence of major liver surgery, especially in liver transplantation with bowel congestion, during which endotoxemia is often evident. The inflammatory response aggravated by endotoxin after I/R contributes to liver dysfunction and failure. The purpose of the present study was to investigate the protective effect of butyrate, a naturally occurring four-carbon fatty acid in the body and a dietary component of foods such as cheese and butter, on hepatic injury complicated by enterogenous endotoxin, as well as to examine the underlying mechanisms involved. SD rats were subjected to a total hepatic ischemia for 30 min after pretreatment with either vehicle or butyrate, followed by 6 h and 24 h of reperfusion. Butyrate preconditioning markedly improved hepatic function and histology, as indicated by reduced transaminase levels and ameliorated tissue pathological changes. The inflammatory factors levels, macrophages activation, TLR4 expression, and neutrophil infiltration in live were attenuated by butyrate. Butyrate also maintained the intestinal barrier structures, reversed the aberrant expression of ZO-1, and decreased the endotoxin translocation. We conclude that butyrate inhibition of endotoxin translocation, macrophages activation, inflammatory factors production, and neutrophil infiltration is involved in the alleviation of total hepatic I/R liver injury in rats. This suggests that butyrate should potentially be utilized in liver transplantation.

  6. Environmentally Reformed Travel Habits During the 2006 Congestion Charge Trial in Stockholm—A Qualitative Study

    PubMed Central

    Henriksson, Greger; Hagman, Olle; Andréasson, Håkan

    2011-01-01

    Policy measures that reduce or replace road traffic can improve environmental conditions in most large cities. In Stockholm a congestion charge was introduced during a test period in 2006. This was a full-scale trial that proved to meet its targets by reducing traffic crossing the inner city segment during rush hours by 20%. Emissions of carbon dioxide and particles were also substantially reduced. This study, based on in-depth interviews with 40 inhabitants, analyses how and why new travel habits emerged. The results show that particular, sometimes unexpected, features of everyday life (habits, resources, opportunities, values, etc.) were crucial for adjustment of travel behaviour in relation to the policy instrument. One example was that those accustomed to mixing different modes of transport on a daily basis more easily adapted their travel in the targeted way. On a more general level, the results revealed that the policy measure could actually tip the scales for the individual towards trying out a new behaviour. PMID:21909301

  7. A sterically congested cis-stilbene and its phosphonium salt precursor.

    PubMed

    Shivaprakash, Shivanna; Reddy, G Chandrasekara; Jasinski, Jerry P; Millikan, Sean P; Duff, Courtney E; Glidewell, Christopher

    2015-06-01

    Triphenyl(2,4,5-trimethoxybenzyl)phosphonium chloride is formed in solvent-free form by the reaction under anhydrous conditions between triphenylphosphane and 2,4,5-trimethoxybenzyl chloride, but when it is crystallized from a mixture of ethyl acetate and chloroform in the presence of air it forms a stoichiometric monohydrate, C28H28O3P(+)·Cl(-)·H2O, (I). The reactions between the anhydrous phosphonium salt and alkoxy-substituted benzaldehydes, using Wittig reactions in the presence of potassium tert-butoxide, provide a series of multiply substituted stilbenes, most of which were assigned the Z configuration on the basis of their NMR spectra. However, no such deduction could be made for the symmetrically substituted (Z)-2,2',4,4',5,5'-hexamethoxystilbene, C20H24O6, (II). Compound (II) does in fact have the Z configuration and the molecular geometry provides evidence for steric congestion around the central double bond; in particular, the central alkene fragment is nonplanar, with a C-C=C-C torsion angle of 7.8 (4)°. In hydrated salt (I), the chloride anions and water molecules are linked by O-H···Cl hydrogen bonds to form C2(1)(4) chains; each cation is linked by C-H···O hydrogen bonds to two different chains, so forming a sheet structure. There are no direction-specific intermolecular interactions in the structure of (II).

  8. Designing a technology enhanced practice for home nursing care of patients with congestive heart failure.

    PubMed

    Casper, Gail R; Karsh, Ben-Tzion; Or, Calvin K L; Carayon, Pascale; Grenier, Anne-Sophie; Brennan, Patricia F

    2005-01-01

    This paper describes the process we used to design the HeartCare website to support Technology Enhanced Practice (TEP) for home care nurses engaged in providing care for patients with Congestive Heart Failure (CHF). Composed of communication, information, and self-monitoring functions, the HeartCare website is aimed at supporting best practice nursing care for these patients. Its unique focus is professional practice, thus the scope of this project is greater and more abstract than those focusing on a task or set of activities. A modified macroergonomic analysis, design work system analysis, and focus groups utilizing participatory design methodology were undertaken to characterize the nursing practice model. Design of the HeartCare website required synthesizing the extant practice model and the agency's evidence-based heart failure protocols, identifying aspects of practice that could be enhanced by supporting technology, and delineation of functional requirements of the Enhanced HeartCare technology. Validation and refinement of the website and planning for user training activities will be accomplished through a two-stage usability testing strategy. PMID:16779013

  9. Wavelet Based Method for Congestive Heart Failure Recognition by Three Confirmation Functions

    PubMed Central

    Daqrouq, K.; Dobaie, A.

    2016-01-01

    An investigation of the electrocardiogram (ECG) signals and arrhythmia characterization by wavelet energy is proposed. This study employs a wavelet based feature extraction method for congestive heart failure (CHF) obtained from the percentage energy (PE) of terminal wavelet packet transform (WPT) subsignals. In addition, the average framing percentage energy (AFE) technique is proposed, termed WAFE. A new classification method is introduced by three confirmation functions. The confirmation methods are based on three concepts: percentage root mean square difference error (PRD), logarithmic difference signal ratio (LDSR), and correlation coefficient (CC). The proposed method showed to be a potential effective discriminator in recognizing such clinical syndrome. ECG signals taken from MIT-BIH arrhythmia dataset and other databases are utilized to analyze different arrhythmias and normal ECGs. Several known methods were studied for comparison. The best recognition rate selection obtained was for WAFE. The recognition performance was accomplished as 92.60% accurate. The Receiver Operating Characteristic curve as a common tool for evaluating the diagnostic accuracy was illustrated, which indicated that the tests are reliable. The performance of the presented system was investigated in additive white Gaussian noise (AWGN) environment, where the recognition rate was 81.48% for 5 dB. PMID:26949412

  10. Reduced Data Dualscale Entropy Analysis of HRV Signals for Improved Congestive Heart Failure Detection

    NASA Astrophysics Data System (ADS)

    Kuntamalla, Srinivas; Lekkala, Ram Gopal Reddy

    2014-10-01

    Heart rate variability (HRV) is an important dynamic variable of the cardiovascular system, which operates on multiple time scales. In this study, Multiscale entropy (MSE) analysis is applied to HRV signals taken from Physiobank to discriminate Congestive Heart Failure (CHF) patients from healthy young and elderly subjects. The discrimination power of the MSE method is decreased as the amount of the data reduces and the lowest amount of the data at which there is a clear discrimination between CHF and normal subjects is found to be 4000 samples. Further, this method failed to discriminate CHF from healthy elderly subjects. In view of this, the Reduced Data Dualscale Entropy Analysis method is proposed to reduce the data size required (as low as 500 samples) for clearly discriminating the CHF patients from young and elderly subjects with only two scales. Further, an easy to interpret index is derived using this new approach for the diagnosis of CHF. This index shows 100 % accuracy and correlates well with the pathophysiology of heart failure.

  11. Implementing a congestive heart failure disease management program to decrease length of stay and cost.

    PubMed

    Knox, D; Mischke, L

    1999-10-01

    Congestive heart failure (CHF) is the most common reason for a hospital admission in the Medicare age group and is nearly double the rate of pneumonia, the next highest volume diagnosis. The economic burden of this debilitating, chronic disease demands a mechanism to improve quality of care while preventing unnecessary hospitalizations. Beginning in 1995, Evanston Northwestern Healthcare (ENH) created a disease management program involving a multidisciplinary team designed to decrease length of stay (national average = 6.2 days; ENH = 4 days), reduce costs, prevent readmissions (national 30-day readmission rate = 23%; ENH CHF Program = 2.3%), and improve compliance with the treatment regimen. Compliance monitoring through an automated telemanagement program reinforces education, identifies early warning signs and reduces the likelihood of hospitalization. After 18 months, telemanagement participants' compliance rate averages 89.5%. CHF hospitalization rates are 0.6/patient/year compared with the national benchmark of 1.7/patient/year. A disease management program consists of inpatient consultation, education, outpatient CHF clinic, cardiac home care, and compliance monitoring. Throughout this continuum, education must be communicated consistently by all team members. A CHF Assessment Guide assists the multidisciplinary team to thoroughly complete all education and address unique solutions to patients' needs.

  12. Environmentally reformed travel habits during the 2006 congestion charge trial in Stockholm--a qualitative study.

    PubMed

    Henriksson, Greger; Hagman, Olle; Andréasson, Håkan

    2011-08-01

    Policy measures that reduce or replace road traffic can improve environmental conditions in most large cities. In Stockholm a congestion charge was introduced during a test period in 2006. This was a full-scale trial that proved to meet its targets by reducing traffic crossing the inner city segment during rush hours by 20%. Emissions of carbon dioxide and particles were also substantially reduced. This study, based on in-depth interviews with 40 inhabitants, analyses how and why new travel habits emerged. The results show that particular, sometimes unexpected, features of everyday life (habits, resources, opportunities, values, etc.) were crucial for adjustment of travel behaviour in relation to the policy instrument. One example was that those accustomed to mixing different modes of transport on a daily basis more easily adapted their travel in the targeted way. On a more general level, the results revealed that the policy measure could actually tip the scales for the individual towards trying out a new behaviour.

  13. Psychiatric comorbidity and mortality among veterans hospitalized for congestive heart failure.

    PubMed

    Banta, Jim E; Andersen, Ronald M; Young, Alexander S; Kominski, Gerald; Cunningham, William E

    2010-10-01

    A Behavioral Model of Health Services Utilization approach was used to examine the impact of comorbid mental illness on mortality of veterans admitted to Veterans Affairs medical centers in fiscal year 2001 with a primary diagnosis of congestive heart failure (n = 15,497). Thirty percent had a psychiatric diagnosis, 4.7% died during the index hospitalization, and 11.5% died during the year following discharge. Among those with mental illness, 23.6% had multiple psychiatric disorders. Multivariable logistic regression models found dementia to be positively associated with inpatient mortality. Depression alone (excluding other psychiatric disorders) was positively associated with one-year mortality. Primary care visits were associated with a reduced likelihood of both inpatient and one-year mortality. Excepting dementia, VA patients with a mental illness had comparable or higher levels of primary care visits than those having no mental illness. Patients with multiple psychiatric disorders had more outpatient care than those with one psychiatric disorder. PMID:20968262

  14. Direct and indirect assessment of skeletal muscle blood flow in chronic congestive heart failure

    SciTech Connect

    LeJemtel, T.H.; Scortichini, D.; Katz, S.

    1988-09-09

    In patients with chronic congestive heart failure (CHF), skeletal muscle blood flow can be measured directly by the continuous thermodilution technique and by the xenon-133 clearance method. The continuous thermodilution technique requires retrograde catheterization of the femoral vein and, thus, cannot be repeated conveniently in patients during evaluation of pharmacologic interventions. The xenon-133 clearance, which requires only an intramuscular injection, allows repeated determination of skeletal muscle blood flow. In patients with severe CHF, a fixed capacity of the skeletal muscle vasculature to dilate appears to limit maximal exercise performance. Moreover, the changes in peak skeletal muscle blood flow noted during long-term administration of captopril, an angiotensin-converting enzyme inhibitor, appears to correlate with the changes in aerobic capacity. In patients with CHF, resting supine deep femoral vein oxygen content can be used as an indirect measurement of resting skeletal muscle blood flow. The absence of a steady state complicates the determination of peak skeletal muscle blood flow reached during graded bicycle or treadmill exercise in patients with chronic CHF. Indirect assessments of skeletal muscle blood flow and metabolism during exercise performed at submaximal work loads are currently developed in patients with chronic CHF.

  15. Communication efficiency and congestion of signal traffic in large-scale brain networks.

    PubMed

    Mišić, Bratislav; Sporns, Olaf; McIntosh, Anthony R

    2014-01-01

    The complex connectivity of the cerebral cortex suggests that inter-regional communication is a primary function. Using computational modeling, we show that anatomical connectivity may be a major determinant for global information flow in brain networks. A macaque brain network was implemented as a communication network in which signal units flowed between grey matter nodes along white matter paths. Compared to degree-matched surrogate networks, information flow on the macaque brain network was characterized by higher loss rates, faster transit times and lower throughput, suggesting that neural connectivity may be optimized for speed rather than fidelity. Much of global communication was mediated by a "rich club" of hub regions: a sub-graph comprised of high-degree nodes that are more densely interconnected with each other than predicted by chance. First, macaque communication patterns most closely resembled those observed for a synthetic rich club network, but were less similar to those seen in a synthetic small world network, suggesting that the former is a more fundamental feature of brain network topology. Second, rich club regions attracted the most signal traffic and likewise, connections between rich club regions carried more traffic than connections between non-rich club regions. Third, a number of rich club regions were significantly under-congested, suggesting that macaque connectivity actively shapes information flow, funneling traffic towards some nodes and away from others. Together, our results indicate a critical role of the rich club of hub nodes in dynamic aspects of global brain communication.

  16. Gunshot wounds: causing myocardial infarction, delayed ventricular septal defect, and congestive heart failure.

    PubMed

    Kumar, Sudeep; Moorthy, Nagaraja; Kapoor, Aditya; Sinha, Nakul

    2012-01-01

    Penetrating chest trauma can cause a wide variety of cardiac injuries, including myocardial contusion, damage to the interventricular septum, laceration of the coronary arteries, and free-wall rupture. Herein, we describe the case of a 21-year-old man who presented with congestive heart failure, which was secondary to an old myocardial infarction and complicated by the delayed formation of a ventricular septal defect. All of these conditions were attributable to multiple gunshot wounds that the patient had sustained 6 months earlier. Left ventricular angiography showed an apical aneurysm; a large, muscular, ventricular septal defect; and 19 gunshot pellets in the chest wall. Three months after aneurysmectomy and surgical closure of the septal defect, the patient had recovered fully and was asymptomatic.This case reaffirms the fact that substantial cardiac injuries can appear months after chest trauma. The possibility of traumatic ventricular septal defect should be considered in all multiple-trauma patients who develop a new heart murmur, even when overt chest-wall injury is absent.

  17. Wavelet Based Method for Congestive Heart Failure Recognition by Three Confirmation Functions.

    PubMed

    Daqrouq, K; Dobaie, A

    2016-01-01

    An investigation of the electrocardiogram (ECG) signals and arrhythmia characterization by wavelet energy is proposed. This study employs a wavelet based feature extraction method for congestive heart failure (CHF) obtained from the percentage energy (PE) of terminal wavelet packet transform (WPT) subsignals. In addition, the average framing percentage energy (AFE) technique is proposed, termed WAFE. A new classification method is introduced by three confirmation functions. The confirmation methods are based on three concepts: percentage root mean square difference error (PRD), logarithmic difference signal ratio (LDSR), and correlation coefficient (CC). The proposed method showed to be a potential effective discriminator in recognizing such clinical syndrome. ECG signals taken from MIT-BIH arrhythmia dataset and other databases are utilized to analyze different arrhythmias and normal ECGs. Several known methods were studied for comparison. The best recognition rate selection obtained was for WAFE. The recognition performance was accomplished as 92.60% accurate. The Receiver Operating Characteristic curve as a common tool for evaluating the diagnostic accuracy was illustrated, which indicated that the tests are reliable. The performance of the presented system was investigated in additive white Gaussian noise (AWGN) environment, where the recognition rate was 81.48% for 5 dB. PMID:26949412

  18. A case of ACTH-independent bilateral macronodular adrenal hyperplasia and severe congestive heart failure.

    PubMed

    Suri, D; Alonso, M; Weiss, R E

    2006-11-01

    Cortisol secretion in ACTH independent bilateral macronodular adrenal hyperplasia (AIMAH) can be regulated by aberrant adrenal receptors. We describe a patient with Cushing's syndrome (CS) due to AIMAH and concomitant Class IV congestive heart failure (CHF). Clinical testing for the presence of aberrant receptors revealed a pronounced serum cortisol (257%) and aldosterone response (212%) to the administration of ACTH and a partial serum cortisol (35%) and aldosterone (106%) response to upright posture. This suggested the possible presence of aberrant hormone receptors for ACTH [melanocortin 2 receptor (MC2-R)], vasopressin, catecholamines or angiotensin II (AT-II) on the patient's adrenal glands. Adrenal tissue from the patient demonstrated an eight-fold increased expression of MC2-R compared to normal adrenal tissue. This increased expression was consistent with the increase in cortisol and aldosterone seen in response to exogenous ACTH. We propose that the severe CHF resulted in activation of the renin-angiotensin system, with an increased production of AT-II. The elevated circulating levels of AT-II may have led to increased expression of MC2-R on the patient's adrenal glands and increased responsiveness to ACTH. This unusual case of CS may elucidate a heretofore unknown mechanism for the development of AIMAH.

  19. Long- and short-time analysis of heartbeat sequences: Correlation with mortality risk in congestive heart failure patients

    NASA Astrophysics Data System (ADS)

    Allegrini, P.; Balocchi, R.; Chillemi, S.; Grigolini, P.; Hamilton, P.; Maestri, R.; Palatella, L.; Raffaelli, G.

    2003-06-01

    We analyze RR heartbeat sequences with a dynamic model that satisfactorily reproduces both the long- and the short-time statistical properties of heart beating. These properties are expressed quantitatively by means of two significant parameters, the scaling δ concerning the asymptotic effects of long-range correlation, and the quantity 1-π establishing the amount of uncorrelated fluctuations. We find a correlation between the position in the phase space (δ,π) of patients with congestive heart failure and their mortality risk.

  20. Cortical Brain Connectivity and B-Type Natriuretic Peptide in Patients With Congestive Heart Failure.

    PubMed

    Vecchio, Fabrizio; Miraglia, Francesca; Valeriani, Lavinia; Scarpellini, Maria Gabriella; Bramanti, Placido; Mecarelli, Oriano; Rossini, Paolo M

    2015-07-01

    The brain has a high level of complexity and needs continuous oxygen supply. So it is clear that any pathological condition, or physiological (aging) change, in the cardiovascular system affects functioning of the central nervous system. We evaluated linear aspects of the relationship between the slowness of cortical rhythms, as revealed by the modulation of a graph connectivity parameter, and congestive heart failure (CHF), as a reflection of neurodegenerative processes. Eyes-closed resting electroencephalographic (EEG) data of 10 patients with CHF were recorded by 19 electrodes positioned according the international 10-20 system. Graph theory function (normalized characteristic path length λ) was applied to the undirected and weighted networks obtained by lagged linear coherence evaluated by eLORETA software, therefore getting rid of volumetric propagation influences. The EEG frequency bands of interest were: delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), beta 2 (20-30 Hz), and gamma (30-40 Hz). The analysis between B-type natriuretic peptide (BNP) values and λ showed positive correlation in delta, associated with a negative correlation in alpha 2 band. Namely, the higher the severity of the disease (as revealed by the BNP vales), the higher the λ in delta, and lower in alpha 2 band. Results suggest that delta and alpha λ indices are good markers of the severity of CHF.