Sample records for ad hoc studies

  1. Ad hoc vs. Non-ad hoc Percutaneous Coronary Intervention Strategies in Patients With Stable Coronary Artery Disease.

    PubMed

    Toyota, Toshiaki; Morimoto, Takeshi; Shiomi, Hiroki; Ando, Kenji; Ono, Koh; Shizuta, Satoshi; Kato, Takao; Saito, Naritatsu; Furukawa, Yutaka; Nakagawa, Yoshihisa; Horie, Minoru; Kimura, Takeshi

    2017-03-24

    Few studies have evaluated the prevalence and clinical outcomes of ad hoc percutaneous coronary intervention (PCI), performing diagnostic coronary angiography and PCI in the same session, in stable coronary artery disease (CAD) patients.Methods and Results:From the CREDO-Kyoto PCI/CABG registry cohort-2, 6,943 patients were analyzed as having stable CAD and undergoing first PCI. Ad hoc PCI and non-ad hoc PCI were performed in 1,722 (24.8%) and 5,221 (75.1%) patients, respectively. The cumulative 5-year incidence and adjusted risk for all-cause death were not significantly different between the 2 groups (15% vs. 15%, P=0.53; hazard ratio: 1.15, 95% confidence interval: 0.98-1.35, P=0.08). Ad hoc PCI relative to non-ad hoc PCI was associated with neutral risk for myocardial infarction, any coronary revascularization, and bleeding, but was associated with a trend towards lower risk for stroke (hazard ratio: 0.78, 95% confidence interval: 0.60-1.02, P=0.06). Ad hoc PCI in stable CAD patients was associated with at least comparable 5-year clinical outcomes as with non-ad hoc PCI. Considering patients' preference and the cost-saving, the ad hoc PCI strategy might be a safe and attractive option for patients with stable CAD, although the prevalence of ad hoc PCI was low in the current study population.

  2. DAWN: Dynamic Ad-hoc Wireless Network

    DTIC Science & Technology

    2016-06-19

    DAWN: Dynamic Ad-hoc Wireless Network The DAWN (Dynamic Ad-hoc Wireless Networks) project is developing a general theory of complex and dynamic... wireless communication networks. To accomplish this, DAWN adopts a very different approach than those followed in the past and summarized above. DAWN... wireless communication networks. The members of DAWN investigated difference aspects of wireless mobile ad hoc networks (MANET). The views, opinions and/or

  3. Ad Hoc Access Gateway Selection Algorithm

    NASA Astrophysics Data System (ADS)

    Jie, Liu

    With the continuous development of mobile communication technology, Ad Hoc access network has become a hot research, Ad Hoc access network nodes can be used to expand capacity of multi-hop communication range of mobile communication system, even business adjacent to the community, improve edge data rates. For mobile nodes in Ad Hoc network to internet, internet communications in the peer nodes must be achieved through the gateway. Therefore, the key Ad Hoc Access Networks will focus on the discovery gateway, as well as gateway selection in the case of multi-gateway and handover problems between different gateways. This paper considers the mobile node and the gateway, based on the average number of hops from an average access time and the stability of routes, improved gateway selection algorithm were proposed. An improved gateway selection algorithm, which mainly considers the algorithm can improve the access time of Ad Hoc nodes and the continuity of communication between the gateways, were proposed. This can improve the quality of communication across the network.

  4. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks.

    PubMed

    Al-Nahari, Abdulaziz; Mohamad, Mohd Murtadha

    2016-01-01

    Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV), which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV) protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV.

  5. Effective Ad-Hoc Committees.

    ERIC Educational Resources Information Center

    Young, David G.

    1983-01-01

    Ad-hoc committees may be symbolic, informational, or action committees. A literature survey indicates such committees' structural components include a suprasystem and three subsystems involving linkages, production, and implementation. Other variables include size, personal factors, and timing. All the factors carry implications about ad-hoc…

  6. Research of Ad Hoc Networks Access Algorithm

    NASA Astrophysics Data System (ADS)

    Xiang, Ma

    With the continuous development of mobile communication technology, Ad Hoc access network has become a hot research, Ad Hoc access network nodes can be used to expand capacity of multi-hop communication range of mobile communication system, even business adjacent to the community, improve edge data rates. When the ad hoc network is the access network of the internet, the gateway discovery protocol is very important to choose the most appropriate gateway to guarantee the connectivity between ad hoc network and IP based fixed networks. The paper proposes a QoS gateway discovery protocol which uses the time delay and stable route to the gateway selection conditions. And according to the gateway discovery protocol, it also proposes a fast handover scheme which can decrease the handover time and improve the handover efficiency.

  7. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks

    PubMed Central

    Al-Nahari, Abdulaziz; Mohamad, Mohd Murtadha

    2016-01-01

    Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV), which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV) protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV. PMID:27258013

  8. Analysis of Pervasive Mobile Ad Hoc Routing Protocols

    NASA Astrophysics Data System (ADS)

    Qadri, Nadia N.; Liotta, Antonio

    Mobile ad hoc networks (MANETs) are a fundamental element of pervasive networks and therefore, of pervasive systems that truly support pervasive computing, where user can communicate anywhere, anytime and on-the-fly. In fact, future advances in pervasive computing rely on advancements in mobile communication, which includes both infrastructure-based wireless networks and non-infrastructure-based MANETs. MANETs introduce a new communication paradigm, which does not require a fixed infrastructure - they rely on wireless terminals for routing and transport services. Due to highly dynamic topology, absence of established infrastructure for centralized administration, bandwidth constrained wireless links, and limited resources in MANETs, it is challenging to design an efficient and reliable routing protocol. This chapter reviews the key studies carried out so far on the performance of mobile ad hoc routing protocols. We discuss performance issues and metrics required for the evaluation of ad hoc routing protocols. This leads to a survey of existing work, which captures the performance of ad hoc routing algorithms and their behaviour from different perspectives and highlights avenues for future research.

  9. Enhanced Weight based DSR for Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Verma, Samant; Jain, Sweta

    2011-12-01

    Routing in ad hoc network is a great problematic, since a good routing protocol must ensure fast and efficient packet forwarding, which isn't evident in ad hoc networks. In literature there exists lot of routing protocols however they don't include all the aspects of ad hoc networks as mobility, device and medium constraints which make these protocols not efficient for some configuration and categories of ad hoc networks. Thus in this paper we propose an improvement of Weight Based DSR in order to include some of the aspects of ad hoc networks as stability, remaining battery power, load and trust factor and proposing a new approach Enhanced Weight Based DSR.

  10. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Ad hoc committees. 1203.903 Section 1203.903 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION INFORMATION SECURITY PROGRAM NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to...

  11. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Ad hoc committees. 1203.903 Section 1203.903 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION INFORMATION SECURITY PROGRAM NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized...

  12. Assured Information Sharing for Ad-Hoc Collaboration

    ERIC Educational Resources Information Center

    Jin, Jing

    2009-01-01

    Collaborative information sharing tends to be highly dynamic and often ad hoc among organizations. The dynamic natures and sharing patterns in ad-hoc collaboration impose a need for a comprehensive and flexible approach to reflecting and coping with the unique access control requirements associated with the environment. This dissertation…

  13. Innovative research of AD HOC network mobility model

    NASA Astrophysics Data System (ADS)

    Chen, Xin

    2017-08-01

    It is difficult for researchers of AD HOC network to conduct actual deployment during experimental stage as the network topology is changeable and location of nodes is unfixed. Thus simulation still remains the main research method of the network. Mobility model is an important component of AD HOC network simulation. It is used to describe the movement pattern of nodes in AD HOC network (including location and velocity, etc.) and decides the movement trail of nodes, playing as the abstraction of the movement modes of nodes. Therefore, mobility model which simulates node movement is an important foundation for simulation research. In AD HOC network research, mobility model shall reflect the movement law of nodes as truly as possible. In this paper, node generally refers to the wireless equipment people carry. The main research contents include how nodes avoid obstacles during movement process and the impacts of obstacles on the mutual relation among nodes, based on which a Node Self Avoiding Obstacle, i.e. NASO model is established in AD HOC network.

  14. Topology Control and Routing in Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Carr-Motyckova, Lenka; Navarra, Alfredo; Johansson, Tomas; Unger, Walter

    Mobile nodes with the ability to communicate with radio signals may form an ad hoc network. In this chapter special problems arising for these ad hoc networks are considered. These include range control, the reduction of interferences, regulation of power consumption, and localization.

  15. Validity of using ad hoc methods to analyze secondary traits in case-control association studies.

    PubMed

    Yung, Godwin; Lin, Xihong

    2016-12-01

    Case-control association studies often collect from their subjects information on secondary phenotypes. Reusing the data and studying the association between genes and secondary phenotypes provide an attractive and cost-effective approach that can lead to discovery of new genetic associations. A number of approaches have been proposed, including simple and computationally efficient ad hoc methods that ignore ascertainment or stratify on case-control status. Justification for these approaches relies on the assumption of no covariates and the correct specification of the primary disease model as a logistic model. Both might not be true in practice, for example, in the presence of population stratification or the primary disease model following a probit model. In this paper, we investigate the validity of ad hoc methods in the presence of covariates and possible disease model misspecification. We show that in taking an ad hoc approach, it may be desirable to include covariates that affect the primary disease in the secondary phenotype model, even though these covariates are not necessarily associated with the secondary phenotype. We also show that when the disease is rare, ad hoc methods can lead to severely biased estimation and inference if the true disease model follows a probit model instead of a logistic model. Our results are justified theoretically and via simulations. Applied to real data analysis of genetic associations with cigarette smoking, ad hoc methods collectively identified as highly significant (P<10-5) single nucleotide polymorphisms from over 10 genes, genes that were identified in previous studies of smoking cessation. © 2016 WILEY PERIODICALS, INC.

  16. Ad hoc instrumentation methods in ecological studies produce highly biased temperature measurements

    USGS Publications Warehouse

    Terando, Adam J.; Youngsteadt, Elsa; Meineke, Emily K.; Prado, Sara G.

    2017-01-01

    In light of global climate change, ecological studies increasingly address effects of temperature on organisms and ecosystems. To measure air temperature at biologically relevant scales in the field, ecologists often use small, portable temperature sensors. Sensors must be shielded from solar radiation to provide accurate temperature measurements, but our review of 18 years of ecological literature indicates that shielding practices vary across studies (when reported at all), and that ecologists often invent and construct ad hoc radiation shields without testing their efficacy. We performed two field experiments to examine the accuracy of temperature observations from three commonly used portable data loggers (HOBO Pro, HOBO Pendant, and iButton hygrochron) housed in manufactured Gill shields or ad hoc, custom‐fabricated shields constructed from everyday materials such as plastic cups. We installed this sensor array (five replicates of 11 sensor‐shield combinations) at weather stations located in open and forested sites. HOBO Pro sensors with Gill shields were the most accurate devices, with a mean absolute error of 0.2°C relative to weather stations at each site. Error in ad hoc shield treatments ranged from 0.8 to 3.0°C, with the largest errors at the open site. We then deployed one replicate of each sensor‐shield combination at five sites that varied in the amount of urban impervious surface cover, which presents a further shielding challenge. Bias in sensors paired with ad hoc shields increased by up to 0.7°C for every 10% increase in impervious surface. Our results indicate that, due to variable shielding practices, the ecological literature likely includes highly biased temperature data that cannot be compared directly across studies. If left unaddressed, these errors will hinder efforts to predict biological responses to climate change. We call for greater standardization in how temperature data are recorded in the field, handled in analyses, and

  17. CSR: Constrained Selfish Routing in Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Bassem, Christine; Bestavros, Azer

    Routing protocols for ad-hoc networks assume that the nodes forming the network are either under a single authority, or else that they would be altruistically forwarding data for other nodes with no expectation of a return. These assumptions are unrealistic since in ad-hoc networks, nodes are likely to be autonomous and rational (selfish), and thus unwilling to help unless they have an incentive to do so. Providing such incentives is an important aspect that should be considered when designing ad-hoc routing protocols. In this paper, we propose a dynamic, decentralized routing protocol for ad-hoc networks that provides incentives in the form of payments to intermediate nodes used to forward data for others. In our Constrained Selfish Routing (CSR) protocol, game-theoretic approaches are used to calculate payments (incentives) that ensure both the truthfulness of participating nodes and the fairness of the CSR protocol. We show through simulations that CSR is an energy efficient protocol and that it provides lower communication overhead in the best and average cases compared to existing approaches.

  18. MWAHCA: A Multimedia Wireless Ad Hoc Cluster Architecture

    PubMed Central

    Diaz, Juan R.; Jimenez, Jose M.; Sendra, Sandra

    2014-01-01

    Wireless Ad hoc networks provide a flexible and adaptable infrastructure to transport data over a great variety of environments. Recently, real-time audio and video data transmission has been increased due to the appearance of many multimedia applications. One of the major challenges is to ensure the quality of multimedia streams when they have passed through a wireless ad hoc network. It requires adapting the network architecture to the multimedia QoS requirements. In this paper we propose a new architecture to organize and manage cluster-based ad hoc networks in order to provide multimedia streams. Proposed architecture adapts the network wireless topology in order to improve the quality of audio and video transmissions. In order to achieve this goal, the architecture uses some information such as each node's capacity and the QoS parameters (bandwidth, delay, jitter, and packet loss). The architecture splits the network into clusters which are specialized in specific multimedia traffic. The real system performance study provided at the end of the paper will demonstrate the feasibility of the proposal. PMID:24737996

  19. MWAHCA: a multimedia wireless ad hoc cluster architecture.

    PubMed

    Diaz, Juan R; Lloret, Jaime; Jimenez, Jose M; Sendra, Sandra

    2014-01-01

    Wireless Ad hoc networks provide a flexible and adaptable infrastructure to transport data over a great variety of environments. Recently, real-time audio and video data transmission has been increased due to the appearance of many multimedia applications. One of the major challenges is to ensure the quality of multimedia streams when they have passed through a wireless ad hoc network. It requires adapting the network architecture to the multimedia QoS requirements. In this paper we propose a new architecture to organize and manage cluster-based ad hoc networks in order to provide multimedia streams. Proposed architecture adapts the network wireless topology in order to improve the quality of audio and video transmissions. In order to achieve this goal, the architecture uses some information such as each node's capacity and the QoS parameters (bandwidth, delay, jitter, and packet loss). The architecture splits the network into clusters which are specialized in specific multimedia traffic. The real system performance study provided at the end of the paper will demonstrate the feasibility of the proposal.

  20. Analysis on Multicast Routing Protocols for Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Xiang, Ma

    As the Mobile Ad Hoc Networks technologies face a series of challenges like dynamic changes of topological structure, existence of unidirectional channel, limited wireless transmission bandwidth, the capability limitations of mobile termination and etc, therefore, the research to mobile Ad Hoc network routings inevitablely undertake a more important task than those to other networks. Multicast is a mode of communication transmission oriented to group computing, which sends the data to a group of host computers by using single source address. In a typical mobile Ad Hoc Network environment, multicast has a significant meaning. On the one hand, the users of mobile Ad Hoc Network usually need to form collaborative working groups; on the other hand, this is also an important means of fully using the broadcast performances of wireless communication and effectively using the limited wireless channel resources. This paper summarizes and comparatively analyzes the routing mechanisms of various existing multicast routing protocols according to the characteristics of mobile Ad Hoc network.

  1. AD HOC Networks for the Autonomous Car

    NASA Astrophysics Data System (ADS)

    Ron, Davidescu; Negrus, Eugen

    2017-10-01

    The future of the vehicle is made of cars, roads and infrastructures connected in a two way automated communication in a holistic system. It is a mandatory to use Encryption to maintain Confidentiality, Integrity and Availability in an ad hoc vehicle network. Vehicle to Vehicle communication, requires multichannel interaction between mobile, moving and changing parties to insure the full benefit from data sharing and real time decision making, a network of such users referred as mobile ad hoc network (MANET), however as ad hoc networks were not implemented in such a scale, it is not clear what is the best method and protocol to apply. Furthermore the visibility of secure preferred asymmetric encrypted ad hoc networks in a real time environment of dense moving autonomous vehicles has to be demonstrated, In order to evaluate the performance of Ad Hoc networks in changing conditions a simulation of multiple protocols was performed on large number of mobile nodes. The following common routing protocols were tested, DSDV is a proactive protocol, every mobile station maintains a routing table with all available destinations, DSR is a reactive routing protocol which allows nodes in the MANET to dynamically discover a source route across multiple network hops, AODV is a reactive routing protocol Instead of being proactive. It minimizes the number of broadcasts by creating routes based on demand, SAODV is a secure version of AODV, requires heavyweight asymmetric cryptographic, ARIANDE is a routing protocol that relies on highly efficient symmetric cryptography the concept is primarily based on DSR. A methodical evolution was performed in a various density of transportation, based on known communication bench mark parameters including, Throughput Vs. time, Routing Load per packets and bytes. Out of the none encrypted protocols, It is clear that in terms of performance of throughput and routing load DSR protocol has a clear advantage the high node number mode. The encrypted

  2. Ad hoc Laser networks component technology for modular spacecraft

    NASA Astrophysics Data System (ADS)

    Huang, Xiujun; Shi, Dele; Ma, Zongfeng; Shen, Jingshi

    2016-03-01

    Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

  3. Ad hoc laser networks component technology for modular spacecraft

    NASA Astrophysics Data System (ADS)

    Huang, Xiujun; Shi, Dele; Shen, Jingshi

    2017-10-01

    Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

  4. Auto-Configuration Protocols in Mobile Ad Hoc Networks

    PubMed Central

    Villalba, Luis Javier García; Matesanz, Julián García; Orozco, Ana Lucila Sandoval; Díaz, José Duván Márquez

    2011-01-01

    The TCP/IP protocol allows the different nodes in a network to communicate by associating a different IP address to each node. In wired or wireless networks with infrastructure, we have a server or node acting as such which correctly assigns IP addresses, but in mobile ad hoc networks there is no such centralized entity capable of carrying out this function. Therefore, a protocol is needed to perform the network configuration automatically and in a dynamic way, which will use all nodes in the network (or part thereof) as if they were servers that manage IP addresses. This article reviews the major proposed auto-configuration protocols for mobile ad hoc networks, with particular emphasis on one of the most recent: D2HCP. This work also includes a comparison of auto-configuration protocols for mobile ad hoc networks by specifying the most relevant metrics, such as a guarantee of uniqueness, overhead, latency, dependency on the routing protocol and uniformity. PMID:22163814

  5. Sputnik: ad hoc distributed computation.

    PubMed

    Völkel, Gunnar; Lausser, Ludwig; Schmid, Florian; Kraus, Johann M; Kestler, Hans A

    2015-04-15

    In bioinformatic applications, computationally demanding algorithms are often parallelized to speed up computation. Nevertheless, setting up computational environments for distributed computation is often tedious. Aim of this project were the lightweight ad hoc set up and fault-tolerant computation requiring only a Java runtime, no administrator rights, while utilizing all CPU cores most effectively. The Sputnik framework provides ad hoc distributed computation on the Java Virtual Machine which uses all supplied CPU cores fully. It provides a graphical user interface for deployment setup and a web user interface displaying the current status of current computation jobs. Neither a permanent setup nor administrator privileges are required. We demonstrate the utility of our approach on feature selection of microarray data. The Sputnik framework is available on Github http://github.com/sysbio-bioinf/sputnik under the Eclipse Public License. hkestler@fli-leibniz.de or hans.kestler@uni-ulm.de Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  6. Trust recovery model of Ad Hoc network based on identity authentication scheme

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Huan, Shuiyuan

    2017-05-01

    Mobile Ad Hoc network trust model is widely used to solve mobile Ad Hoc network security issues. Aiming at the problem of reducing the network availability caused by the processing of malicious nodes and selfish nodes in mobile Ad Hoc network routing based on trust model, an authentication mechanism based on identity authentication mobile Ad Hoc network is proposed, which uses identity authentication to identify malicious nodes, And trust the recovery of selfish nodes in order to achieve the purpose of reducing network congestion and improving network quality. The simulation results show that the implementation of the mechanism can effectively improve the network availability and security.

  7. Hybrid Packet-Pheromone-Based Probabilistic Routing for Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Kashkouli Nejad, Keyvan; Shawish, Ahmed; Jiang, Xiaohong; Horiguchi, Susumu

    Ad-Hoc networks are collections of mobile nodes communicating using wireless media without any fixed infrastructure. Minimal configuration and quick deployment make Ad-Hoc networks suitable for emergency situations like natural disasters or military conflicts. The current Ad-Hoc networks can only support either high mobility or high transmission rate at a time because they employ static approaches in their routing schemes. However, due to the continuous expansion of the Ad-Hoc network size, node-mobility and transmission rate, the development of new adaptive and dynamic routing schemes has become crucial. In this paper we propose a new routing scheme to support high transmission rates and high node-mobility simultaneously in a big Ad-Hoc network, by combining a new proposed packet-pheromone-based approach with the Hint Based Probabilistic Protocol (HBPP) for congestion avoidance with dynamic path selection in packet forwarding process. Because of using the available feedback information, the proposed algorithm does not introduce any additional overhead. The extensive simulation-based analysis conducted in this paper indicates that the proposed algorithm offers small packet-latency and achieves a significantly higher delivery probability in comparison with the available Hint-Based Probabilistic Protocol (HBPP).

  8. Quantum load balancing in ad hoc networks

    NASA Astrophysics Data System (ADS)

    Hasanpour, M.; Shariat, S.; Barnaghi, P.; Hoseinitabatabaei, S. A.; Vahid, S.; Tafazolli, R.

    2017-06-01

    This paper presents a novel approach in targeting load balancing in ad hoc networks utilizing the properties of quantum game theory. This approach benefits from the instantaneous and information-less capability of entangled particles to synchronize the load balancing strategies in ad hoc networks. The quantum load balancing (QLB) algorithm proposed by this work is implemented on top of OLSR as the baseline routing protocol; its performance is analyzed against the baseline OLSR, and considerable gain is reported regarding some of the main QoS metrics such as delay and jitter. Furthermore, it is shown that QLB algorithm supports a solid stability gain in terms of throughput which stands a proof of concept for the load balancing properties of the proposed theory.

  9. Supporting Dynamic Ad hoc Collaboration Capabilities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Agarwal, Deborah A.; Berket, Karlo

    2003-07-14

    Modern HENP experiments such as CMS and Atlas involve as many as 2000 collaborators around the world. Collaborations this large will be unable to meet often enough to support working closely together. Many of the tools currently available for collaboration focus on heavy-weight applications such as videoconferencing tools. While these are important, there is a more basic need for tools that support connecting physicists to work together on an ad hoc or continuous basis. Tools that support the day-to-day connectivity and underlying needs of a group of collaborators are important for providing light-weight, non-intrusive, and flexible ways to work collaboratively.more » Some example tools include messaging, file-sharing, and shared plot viewers. An important component of the environment is a scalable underlying communication framework. In this paper we will describe our current progress on building a dynamic and ad hoc collaboration environment and our vision for its evolution into a HENP collaboration environment.« less

  10. A Decentralized VPN Service over Generalized Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Fujita, Sho; Shima, Keiichi; Uo, Yojiro; Esaki, Hiroshi

    We present a decentralized VPN service that can be built over generalized mobile ad-hoc networks (Generalized MANETs), in which topologies can be represented as a time-varying directed multigraph. We address wireless ad-hoc networks and overlay ad-hoc networks as instances of Generalized MANETs. We first propose an architecture to operate on various kinds of networks through a single set of operations. Then, we design and implement a decentralized VPN service on the proposed architecture. Through the development and operation of a prototype system we implemented, we found that the proposed architecture makes the VPN service applicable to each instance of Generalized MANETs, and that the VPN service makes it possible for unmodified applications to operate on the networks.

  11. Intelligent Sensing and Classification in DSR-Based Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Dempsey, Tae; Sahin, Gokhan; Morton, Yu T. (Jade

    Wireless ad hoc networks have fundamentally altered today's battlefield, with applications ranging from unmanned air vehicles to randomly deployed sensor networks. Security and vulnerabilities in wireless ad hoc networks have been considered at different layers, and many attack strategies have been proposed, including denial of service (DoS) through the intelligent jamming of the most critical packet types of flows in a network. This paper investigates the effectiveness of intelligent jamming in wireless ad hoc networks using the Dynamic Source Routing (DSR) and TCP protocols and introduces an intelligent classifier to facilitate the jamming of such networks. Assuming encrypted packet headers and contents, our classifier is based solely on the observable characteristics of size, inter-arrival timing, and direction and classifies packets with up to 99.4% accuracy in our experiments.

  12. Initial Report of the Deans Cyber Warfare Ad Hoc Committee

    DTIC Science & Technology

    2011-12-22

    in a cyber warfare environment. Among the more notable recent developments have been the establishment of a new Cyber Warfare Command (USCYBERCOM) at...information-warfare-centric organization. Clearly, future Naval Academy graduates will be expected to know more about cyber warfare than those we have...graduated in the past. The Academic Dean and Provost tasked an ad hoc committeethe Cyber Warfare ad hoc Committeeto examine how USNA can best ensure that

  13. Global Coverage from Ad-Hoc Constellations in Rideshare Orbits

    NASA Technical Reports Server (NTRS)

    Ellis, Armin; Mercury, Michael; Brown, Shannon

    2012-01-01

    A promising area of small satellite development is in providing higher temporal resolution than larger satellites. Traditional constellations have required specific orbits and dedicated launch vehicles. In this paper we discuss an alternative architecture in which the individual elements of the constellation are launched as rideshare opportunities. We compare the coverage of such an ad-hoc constellation with more traditional constellations. Coverage analysis is based on actual historical data from rideshare opportunities. Our analysis includes ground coverage and temporal revisits for Polar, Tropics, Temperate, and Global regions, comparing ad-hoc and Walker constellation.

  14. The effects of malicious nodes on performance of mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Li, Fanzhi; Shi, Xiyu; Jassim, Sabah; Adams, Christopher

    2006-05-01

    Wireless ad hoc networking offers convenient infrastructureless communication over the shared wireless channel. However, the nature of ad hoc networks makes them vulnerable to security attacks. Unlike their wired counterpart, infrastructureless ad hoc networks do not have a clear line of defense, their topology is dynamically changing, and every mobile node can receive messages from its neighbors and can be contacted by all other nodes in its neighborhood. This poses a great danger to network security if some nodes behave in a malicious manner. The immediate concern about the security in this type of networks is how to protect the network and the individual mobile nodes against malicious act of rogue nodes from within the network. This paper is concerned with security aspects of wireless ad hoc networks. We shall present results of simulation experiments on ad hoc network's performance in the presence of malicious nodes. We shall investigate two types of attacks and the consequences will be simulated and quantified in terms of loss of packets and other factors. The results show that network performance, in terms of successful packet delivery ratios, significantly deteriorates when malicious nodes act according to the defined misbehaving characteristics.

  15. Packets Distributing Evolutionary Algorithm Based on PSO for Ad Hoc Network

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-Feng

    2018-03-01

    Wireless communication network has such features as limited bandwidth, changeful channel and dynamic topology, etc. Ad hoc network has lots of difficulties in accessing control, bandwidth distribution, resource assign and congestion control. Therefore, a wireless packets distributing Evolutionary algorithm based on PSO (DPSO)for Ad Hoc Network is proposed. Firstly, parameters impact on performance of network are analyzed and researched to obtain network performance effective function. Secondly, the improved PSO Evolutionary Algorithm is used to solve the optimization problem from local to global in the process of network packets distributing. The simulation results show that the algorithm can ensure fairness and timeliness of network transmission, as well as improve ad hoc network resource integrated utilization efficiency.

  16. Ad Hoc Information Extraction for Clinical Data Warehouses.

    PubMed

    Dietrich, Georg; Krebs, Jonathan; Fette, Georg; Ertl, Maximilian; Kaspar, Mathias; Störk, Stefan; Puppe, Frank

    2018-05-01

    Clinical Data Warehouses (CDW) reuse Electronic health records (EHR) to make their data retrievable for research purposes or patient recruitment for clinical trials. However, much information are hidden in unstructured data like discharge letters. They can be preprocessed and converted to structured data via information extraction (IE), which is unfortunately a laborious task and therefore usually not available for most of the text data in CDW. The goal of our work is to provide an ad hoc IE service that allows users to query text data ad hoc in a manner similar to querying structured data in a CDW. While search engines just return text snippets, our systems also returns frequencies (e.g. how many patients exist with "heart failure" including textual synonyms or how many patients have an LVEF < 45) based on the content of discharge letters or textual reports for special investigations like heart echo. Three subtasks are addressed: (1) To recognize and to exclude negations and their scopes, (2) to extract concepts, i.e. Boolean values and (3) to extract numerical values. We implemented an extended version of the NegEx-algorithm for German texts that detects negations and determines their scope. Furthermore, our document oriented CDW PaDaWaN was extended with query functions, e.g. context sensitive queries and regex queries, and an extraction mode for computing the frequencies for Boolean and numerical values. Evaluations in chest X-ray reports and in discharge letters showed high F1-scores for the three subtasks: Detection of negated concepts in chest X-ray reports with an F1-score of 0.99 and in discharge letters with 0.97; of Boolean values in chest X-ray reports about 0.99, and of numerical values in chest X-ray reports and discharge letters also around 0.99 with the exception of the concept age. The advantages of an ad hoc IE over a standard IE are the low development effort (just entering the concept with its variants), the promptness of the results and the

  17. A Group Based Key Sharing and Management Algorithm for Vehicular Ad Hoc Networks

    PubMed Central

    Moharram, Mohammed Morsi; Azam, Farzana

    2014-01-01

    Vehicular ad hoc networks (VANETs) are one special type of ad hoc networks that involves vehicles on roads. Typically like ad hoc networks, broadcast approach is used for data dissemination. Blind broadcast to each and every node results in exchange of useless and irrelevant messages and hence creates an overhead. Unicasting is not preferred in ad-hoc networks due to the dynamic topology and the resource requirements as compared to broadcasting. Simple broadcasting techniques create several problems on privacy, disturbance, and resource utilization. In this paper, we propose media mixing algorithm to decide what information should be provided to each user and how to provide such information. Results obtained through simulation show that fewer number of keys are needed to share compared to simple broadcasting. Privacy is also enhanced through this approach. PMID:24587749

  18. Decentralized session initiation protocol solution in ad hoc networks

    NASA Astrophysics Data System (ADS)

    Han, Lu; Jin, Zhigang; Shu, Yantai; Dong, Linfang

    2006-10-01

    With the fast development of ad hoc networks, SIP has attracted more and more attention in multimedia service. This paper proposes a new architecture to provide SIP service for ad hoc users, although there is no centralized SIP server deployed. In this solution, we provide the SIP service by the introduction of two nodes: Designated SIP Server (DS) and its Backup Server (BDS). The nodes of ad hoc network designate DS and BDS when they join the session nodes set and when some pre-defined events occur. A new sip message type called REGISTRAR is presented so nodes can send others REGISTRAR message to declare they want to be DS. According to the IP information taken in the message, an algorithm works like the election of DR and BDR in OSPF protocol is used to vote DS and BDS SIP servers. Naturally, the DS will be replaced by BDS when the DS is down for predicable or unpredictable reasons. To facilitate this, the DS should register to the BDS and transfer a backup of the SIP users' database. Considering the possibility DS or BDS may abruptly go down, a special policy is given. When there is no DS and BDS, a new election procedure is triggered just like the startup phase. The paper also describes how SIP works normally in the decentralized model as well as the evaluation of its performance. All sessions based on SIP in ad hoc such as DS voting have been tested in the real experiments within a 500m*500m square area where about 30 random nodes are placed.

  19. Information Sharing Modalities for Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    de Spindler, Alexandre; Grossniklaus, Michael; Lins, Christoph; Norrie, Moira C.

    Current mobile phone technologies have fostered the emergence of a new generation of mobile applications. Such applications allow users to interact and share information opportunistically when their mobile devices are in physical proximity or close to fixed installations. It has been shown how mobile applications such as collaborative filtering and location-based services can take advantage of ad-hoc connectivity to use physical proximity as a filter mechanism inherent to the application logic. We discuss the different modes of information sharing that arise in such settings based on the models of persistence and synchronisation. We present a platform that supports the development of applications that can exploit these modes of ad-hoc information sharing and, by means of an example, show how such an application can be realised based on the supported event model.

  20. Interference Drop Scheme: Enhancing QoS Provision in Multi-Hop Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Luo, Chang-Yi; Komuro, Nobuyoshi; Takahashi, Kiyoshi; Kasai, Hiroyuki; Ueda, Hiromi; Tsuboi, Toshinori

    Ad hoc networking uses wireless technologies to construct networks with no physical infrastructure and so are expected to provide instant networking in areas such as disaster recovery sites and inter-vehicle communication. Unlike conventional wired networks services, services in ad hoc networks are easily disrupted by the frequent changes in traffic and topology. Therefore, solutions to assure the Quality of Services (QoS) in ad hoc networks are different from the conventional ones used in wired networks. In this paper, we propose a new queue management scheme, Interference Drop Scheme (IDS) for ad hoc networks. In the conventional queue management approaches such as FIFO (First-in First-out) and RED (Random Early Detection), a queue is usually managed by a queue length limit. FIFO discards packets according to the queue limit, and RED discards packets in an early and random fashion. IDS, on the other hand, manages the queue according to wireless interference time, which increases as the number of contentions in the MAC layer increases. When there are many MAC contentions, IDS discards TCP data packets. By observing the interference time and discarding TCP data packets, our simulation results show that IDS improves TCP performance and reduces QoS violations in UDP in ad hoc networks with chain, grid, and random topologies. Our simulation results also demonstrate that wireless interference time is a better metric than queue length limit for queue management in multi-hop ad hoc networks.

  1. Anomaly Detection Techniques for Ad Hoc Networks

    ERIC Educational Resources Information Center

    Cai, Chaoli

    2009-01-01

    Anomaly detection is an important and indispensable aspect of any computer security mechanism. Ad hoc and mobile networks consist of a number of peer mobile nodes that are capable of communicating with each other absent a fixed infrastructure. Arbitrary node movements and lack of centralized control make them vulnerable to a wide variety of…

  2. MAC Protocol for Ad Hoc Networks Using a Genetic Algorithm

    PubMed Central

    Elizarraras, Omar; Panduro, Marco; Méndez, Aldo L.

    2014-01-01

    The problem of obtaining the transmission rate in an ad hoc network consists in adjusting the power of each node to ensure the signal to interference ratio (SIR) and the energy required to transmit from one node to another is obtained at the same time. Therefore, an optimal transmission rate for each node in a medium access control (MAC) protocol based on CSMA-CDMA (carrier sense multiple access-code division multiple access) for ad hoc networks can be obtained using evolutionary optimization. This work proposes a genetic algorithm for the transmission rate election considering a perfect power control, and our proposition achieves improvement of 10% compared with the scheme that handles the handshaking phase to adjust the transmission rate. Furthermore, this paper proposes a genetic algorithm that solves the problem of power combining, interference, data rate, and energy ensuring the signal to interference ratio in an ad hoc network. The result of the proposed genetic algorithm has a better performance (15%) compared to the CSMA-CDMA protocol without optimizing. Therefore, we show by simulation the effectiveness of the proposed protocol in terms of the throughput. PMID:25140339

  3. 75 FR 43565 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-26

    ... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice: (10-084)] NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION... amended, the National Aeronautics and Space Administration announces a two-part meeting of the Ad-Hoc Task...

  4. 75 FR 33838 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice (10-065)] NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION... amended, the National Aeronautics and Space Administration announces a meeting of the Ad-Hoc Task Force on...

  5. 75 FR 15742 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-30

    ... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice: (10-035)] NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION... amended, the National Aeronautics and Space Administration announces a meeting of the Ad-Hoc Task Force on...

  6. Providing Location Security in Vehicular Ad Hoc Networks

    ERIC Educational Resources Information Center

    Yan, Gongjun

    2010-01-01

    Location is fundamental information in Vehicular Ad-hoc Networks (VANETs). Almost all VANET applications rely on location information. Therefore it is of importance to ensure location information integrity, meaning that location information is original (from the generator), correct (not bogus or fabricated) and unmodified (value not changed). We…

  7. What Is the Problem of Ad Hoc Hypotheses?

    ERIC Educational Resources Information Center

    Bamford, Greg

    1999-01-01

    Philosophers' attempts to convincingly explicate the received view of an ad hoc hypothesis--that it accounts for only the observations it was designed to account for--have been unsuccessful. Familiar and firmer criteria for evaluating the hypotheses or modified theories so classified are characteristically available. Contains 41 references.…

  8. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad...

  9. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad...

  10. Strategies for generating multiple instances of common and ad hoc categories.

    PubMed

    Vallée-Tourangeau, F; Anthony, S H; Austin, N G

    1998-09-01

    In a free-emission procedure participants were asked to generate instances of a given category and to report, retrospectively, the strategies that they were aware of using in retrieving instances. In two studies reported here, participants generated instances for common categories (e.g. fruit) and for ad hoc categories (e.g., things people keep in their pockets) for 90 seconds and for each category described how they had proceeded in doing so. Analysis of the protocols identified three broad classes of strategy: (1) experiential, where memories of specific or generic personal experiences involving interactions with the category instances acted as cues; (2) semantic, where a consideration of abstract conceptual characteristics of a category were employed to retrieve category exemplars; (3) unmediated, where instances were effortlessly retrieved without mediating cognitions of which subjects were aware. Experiential strategies outnumbered semantic strategies (on average 4 to 1) not only for ad hoc categories but also for common categories. This pattern was noticeably reversed for ad hoc categories that subjects were unlikely to have experienced personally (e.g. things sold on the black market in Russia). Whereas more traditional accounts of semantic memory have favoured decontextualised abstract representations of category knowledge, to the extent that mode of access informs us of knowledge structures, our data suggest that category knowledge is significantly grounded in terms of everyday contexts where category instances are encountered.

  11. Taxonomic and ad hoc categorization within the two cerebral hemispheres.

    PubMed

    Shen, Yeshayahu; Aharoni, Bat-El; Mashal, Nira

    2015-01-01

    A typicality effect refers to categorization which is performed more quickly or more accurately for typical than for atypical members of a given category. Previous studies reported a typicality effect for category members presented in the left visual field/right hemisphere (RH), suggesting that the RH applies a similarity-based categorization strategy. However, findings regarding the typicality effect within the left hemisphere (LH) are less conclusive. The current study tested the pattern of typicality effects within each hemisphere for both taxonomic and ad hoc categories, using words presented to the left or right visual fields. Experiment 1 tested typical and atypical members of taxonomic categories as well as non-members, and Experiment 2 tested typical and atypical members of ad hoc categories as well as non-members. The results revealed a typicality effect in both hemispheres and in both types of categories. Furthermore, the RH categorized atypical stimuli more accurately than did the LH. Our findings suggest that both hemispheres rely on a similarity-based categorization strategy, but the coarse semantic coding of the RH seems to facilitate the categorization of atypical members.

  12. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks.

    PubMed

    Vara, M Isabel; Campo, Celeste

    2015-07-20

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead.

  13. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks

    PubMed Central

    Vara, M. Isabel; Campo, Celeste

    2015-01-01

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead. PMID:26205272

  14. Data Mining of Extremely Large Ad Hoc Data Sets to Produce Inverted Indices

    DTIC Science & Technology

    2016-06-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited DATA MINING OF...COVERED Master’s Thesis 4. TITLE AND SUBTITLE DATA MINING OF EXTREMELY LARGE AD HOC DATA SETS TO PRODUCE INVERTED INDICES 5. FUNDING NUMBERS 6...INTENTIONALLY LEFT BLANK iii Approved for public release; distribution is unlimited DATA MINING OF EXTREMELY LARGE AD HOC DATA SETS TO PRODUCE

  15. Typicality Mediates Performance during Category Verification in Both Ad-Hoc and Well-Defined Categories

    ERIC Educational Resources Information Center

    Sandberg, Chaleece; Sebastian, Rajani; Kiran, Swathi

    2012-01-01

    Background: The typicality effect is present in neurologically intact populations for natural, ad-hoc, and well-defined categories. Although sparse, there is evidence of typicality effects in persons with chronic stroke aphasia for natural and ad-hoc categories. However, it is unknown exactly what influences the typicality effect in this…

  16. On Trust Evaluation in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Nguyen, Dang Quan; Lamont, Louise; Mason, Peter C.

    Trust has been considered as a social relationship between two individuals in human society. But, as computer science and networking have succeeded in using computers to automate many tasks, the concept of trust can be generalized to cover the reliability and relationships of non-human interaction, such as, for example, information gathering and data routing. This paper investigates the evaluation of trust in the context of ad hoc networks. Nodes evaluate each other’s behaviour based on observables. A node then decides whether to trust another node to have certain innate abilities. We show how accurate such an evaluation could be. We also provide the minimum number of observations required to obtain an accurate evaluation, a result that indicates that observation-based trust in ad hoc networks will remain a challenging problem. The impact of making networking decisions using trust evaluation on the network connectivity is also examined. In this manner, quantitative decisions can be made concerning trust-based routing with the knowledge of the potential impact on connectivity.

  17. Impact of network structure on the capacity of wireless multihop ad hoc communication

    NASA Astrophysics Data System (ADS)

    Krause, Wolfram; Glauche, Ingmar; Sollacher, Rudolf; Greiner, Martin

    2004-07-01

    As a representative of a complex technological system, the so-called wireless multihop ad hoc communication networks are discussed. They represent an infrastructure-less generalization of todays wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to coordinate themselves such that the overall network performs in an optimal way. A performance indicator is the end-to-end throughput capacity. Various models, generating differing ad hoc network structure via differing transmission power assignments, are constructed and characterized. They serve as input for a generic data traffic simulation as well as some semi-analytic estimations. The latter reveal that due to the most-critical-node effect the end-to-end throughput capacity sensitively depends on the underlying network structure, resulting in differing scaling laws with respect to network size.

  18. Conflict Management in "Ad Hoc" Problem-Solving Groups: A Preliminary Investigation.

    ERIC Educational Resources Information Center

    Wallace, Les; Baxter, Leslie

    Full study of small group communication must include consideration of task and socio-emotional dimensions, especially in relation to group problem solving. Thirty small groups were tested for their reactions in various "ad hoc" conflict resolution situations. Instructions to the groups were (1) no problem-solving instructions (control),…

  19. Ad Hoc Categories and False Memories: Memory Illusions for Categories Created On-The-Spot

    ERIC Educational Resources Information Center

    Soro, Jerônimo C.; Ferreira, Mário B.; Semin, Gün R.; Mata, André; Carneiro, Paula

    2017-01-01

    Three experiments were designed to test whether experimentally created ad hoc associative networks evoke false memories. We used the DRM (Deese, Roediger, McDermott) paradigm with lists of ad hoc categories composed of exemplars aggregated toward specific goals (e.g., going for a picnic) that do not share any consistent set of features. Experiment…

  20. Distributed generation of shared RSA keys in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Liang; Huang, Qin; Shen, Ying

    2005-12-01

    Mobile Ad Hoc Networks is a totally new concept in which mobile nodes are able to communicate together over wireless links in an independent manner, independent of fixed physical infrastructure and centralized administrative infrastructure. However, the nature of Ad Hoc Networks makes them very vulnerable to security threats. Generation and distribution of shared keys for CA (Certification Authority) is challenging for security solution based on distributed PKI(Public-Key Infrastructure)/CA. The solutions that have been proposed in the literature and some related issues are discussed in this paper. The solution of a distributed generation of shared threshold RSA keys for CA is proposed in the present paper. During the process of creating an RSA private key share, every CA node only has its own private security. Distributed arithmetic is used to create the CA's private share locally, and that the requirement of centralized management institution is eliminated. Based on fully considering the Mobile Ad Hoc network's characteristic of self-organization, it avoids the security hidden trouble that comes by holding an all private security share of CA, with which the security and robustness of system is enhanced.

  1. Capacity-Delay Trade-Off in Collaborative Hybrid Ad-Hoc Networks with Coverage Sensing.

    PubMed

    Chen, Lingyu; Luo, Wenbin; Liu, Chen; Hong, Xuemin; Shi, Jianghong

    2017-01-26

    The integration of ad hoc device-to-device (D2D) communications and open-access small cells can result in a networking paradigm called hybrid the ad hoc network, which is particularly promising in delivering delay-tolerant data. The capacity-delay performance of hybrid ad hoc networks has been studied extensively under a popular framework called scaling law analysis. These studies, however, do not take into account aspects of interference accumulation and queueing delay and, therefore, may lead to over-optimistic results. Moreover, focusing on the average measures, existing works fail to give finer-grained insights into the distribution of delays. This paper proposes an alternative analytical framework based on queueing theoretic models and physical interference models. We apply this framework to study the capacity-delay performance of a collaborative cellular D2D network with coverage sensing and two-hop relay. The new framework allows us to fully characterize the delay distribution in the transform domain and pinpoint the impacts of coverage sensing, user and base station densities, transmit power, user mobility and packet size on the capacity-delay trade-off. We show that under the condition of queueing equilibrium, the maximum throughput capacity per device saturates to an upper bound of 0.7239 λ b / λ u bits/s/Hz, where λ b and λ u are the densities of base stations and mobile users, respectively.

  2. Capacity-Delay Trade-Off in Collaborative Hybrid Ad-Hoc Networks with Coverage Sensing

    PubMed Central

    Chen, Lingyu; Luo, Wenbin; Liu, Chen; Hong, Xuemin; Shi, Jianghong

    2017-01-01

    The integration of ad hoc device-to-device (D2D) communications and open-access small cells can result in a networking paradigm called hybrid the ad hoc network, which is particularly promising in delivering delay-tolerant data. The capacity-delay performance of hybrid ad hoc networks has been studied extensively under a popular framework called scaling law analysis. These studies, however, do not take into account aspects of interference accumulation and queueing delay and, therefore, may lead to over-optimistic results. Moreover, focusing on the average measures, existing works fail to give finer-grained insights into the distribution of delays. This paper proposes an alternative analytical framework based on queueing theoretic models and physical interference models. We apply this framework to study the capacity-delay performance of a collaborative cellular D2D network with coverage sensing and two-hop relay. The new framework allows us to fully characterize the delay distribution in the transform domain and pinpoint the impacts of coverage sensing, user and base station densities, transmit power, user mobility and packet size on the capacity-delay trade-off. We show that under the condition of queueing equilibrium, the maximum throughput capacity per device saturates to an upper bound of 0.7239 λb/λu bits/s/Hz, where λb and λu are the densities of base stations and mobile users, respectively. PMID:28134769

  3. Energy Efficient and QoS sensitive Routing Protocol for Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Saeed Tanoli, Tariq; Khalid Khan, Muhammad

    2013-12-01

    Efficient routing is an important part of wireless ad hoc networks. Since in ad hoc networks we have limited resources, there are many limitations like bandwidth, battery consumption, and processing cycle etc. Reliability is also necessary since there is no allowance for invalid or incomplete information (and expired data is useless). There are various protocols that perform routing by considering one parameter but ignoring other parameters. In this paper we present a protocol that finds route on the basis of bandwidth, energy and mobility of the nodes participating in the communication.

  4. Passive and Active Analysis in DSR-Based Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Dempsey, Tae; Sahin, Gokhan; Morton, Y. T. (Jade)

    Security and vulnerabilities in wireless ad hoc networks have been considered at different layers, and many attack strategies have been proposed, including denial of service (DoS) through the intelligent jamming of the most critical packet types of flows in a network. This paper investigates the effectiveness of intelligent jamming in wireless ad hoc networks using the Dynamic Source Routing (DSR) and TCP protocols and introduces an intelligent classifier to facilitate the jamming of such networks. Assuming encrypted packet headers and contents, our classifier is based solely on the observable characteristics of size, inter-arrival timing, and direction and classifies packets with up to 99.4% accuracy in our experiments. Furthermore, we investigate active analysis, which is the combination of a classifier and intelligent jammer to invoke specific responses from a victim network.

  5. Reputation-Based Internet Protocol Security: A Multilayer Security Framework for Mobile Ad Hoc Networks

    DTIC Science & Technology

    2010-09-01

    secure ad-hoc networks of mobile sensors deployed in a hostile environment . These sensors are normally small 86 and resource...Communications Magazine, 51, 2008. 45. Kumar, S.A. “Classification and Review of Security Schemes in Mobile Comput- ing”. Wireless Sensor Network , 2010... Networks ”. Wireless /Mobile Network Security , 2008. 85. Xiao, Y. “Accountability for Wireless LANs, Ad Hoc Networks , and Wireless

  6. Intelligent routing protocol for ad hoc wireless network

    NASA Astrophysics Data System (ADS)

    Peng, Chaorong; Chen, Chang Wen

    2006-05-01

    A novel routing scheme for mobile ad hoc networks (MANETs), which combines hybrid and multi-inter-routing path properties with a distributed topology discovery route mechanism using control agents is proposed in this paper. In recent years, a variety of hybrid routing protocols for Mobile Ad hoc wireless networks (MANETs) have been developed. Which is proactively maintains routing information for a local neighborhood, while reactively acquiring routes to destinations beyond the global. The hybrid protocol reduces routing discovery latency and the end-to-end delay by providing high connectivity without requiring much of the scarce network capacity. On the other side the hybrid routing protocols in MANETs likes Zone Routing Protocol still need route "re-discover" time when a route between zones link break. Sine the topology update information needs to be broadcast routing request on local zone. Due to this delay, the routing protocol may not be applicable for real-time data and multimedia communication. We utilize the advantages of a clustering organization and multi-routing path in routing protocol to achieve several goals at the same time. Firstly, IRP efficiently saves network bandwidth and reduces route reconstruction time when a routing path fails. The IRP protocol does not require global periodic routing advertisements, local control agents will automatically monitor and repair broke links. Secondly, it efficiently reduces congestion and traffic "bottlenecks" for ClusterHeads in clustering network. Thirdly, it reduces significant overheads associated with maintaining clusters. Fourthly, it improves clusters stability due to dynamic topology changing frequently. In this paper, we present the Intelligent Routing Protocol. First, we discuss the problem of routing in ad hoc networks and the motivation of IRP. We describe the hierarchical architecture of IRP. We describe the routing process and illustrate it with an example. Further, we describe the control manage

  7. UMDR: Multi-Path Routing Protocol for Underwater Ad Hoc Networks with Directional Antenna

    NASA Astrophysics Data System (ADS)

    Yang, Jianmin; Liu, Songzuo; Liu, Qipei; Qiao, Gang

    2018-01-01

    This paper presents a new routing scheme for underwater ad hoc networks based on directional antennas. Ad hoc networks with directional antennas have become a hot research topic because of space reuse may increase networks capacity. At present, researchers have applied traditional self-organizing routing protocols (such as DSR, AODV) [1] [2] on this type of networks, and the routing scheme is based on the shortest path metric. However, such routing schemes often suffer from long transmission delays and frequent link fragmentation along the intermediate nodes of the selected route. This is caused by a unique feature of directional transmission, often called as “deafness”. In this paper, we take a different approach to explore the advantages of space reuse through multipath routing. This paper introduces the validity of the conventional routing scheme in underwater ad hoc networks with directional antennas, and presents a special design of multipath routing algorithm for directional transmission. The experimental results show a significant performance improvement in throughput and latency.

  8. Cutting Corners: Provider Perceptions of Interpretation Services and Factors Related to Use of an Ad Hoc Interpreter.

    PubMed

    Mayo, Rachel; Parker, Veronica G; Sherrill, Windsor W; Coltman, Kinneil; Hudson, Matthew F; Nichols, Christina M; Yates, Adam M; Pribonic, Anne Paige

    2016-06-01

    This study assessed health providers' perceptions of factors related to professional interpretation services and the association between these factors and the potential use of ad hoc interpreters. Data were collected from a convenience sample of 150 health services providers at a large, regional health system in South Carolina. Providers rated "ability to communicate effectively during a clinical encounter" as paramount regarding the use of interpretation services. The most important factors related to the likely use of ad hoc interpreters (cutting corners) included locating a qualified interpreter, having to wait for a qualified interpreter, and technical difficulties regarding phone and video technology. Health care organizations may benefit from increasing staff awareness about patient safety and legal and regulatory risks involved with the use of ad hoc interpreters. © The Author(s) 2016.

  9. Two Phase Admission Control for QoS Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Chen, Chien-Sheng; Su, Yi-Wen; Liu, Wen-Hsiung; Chi, Ching-Lung

    In this paper a novel and effective two phase admission control (TPAC) for QoS mobile ad hoc networks is proposed that satisfies the real-time traffic requirements in mobile ad hoc networks. With a limited amount of extra overhead, TPAC can avoid network congestions by a simple and precise admission control which blocks most of the overloading flow-requests in the route discovery process. When compared with previous QoS routing schemes such as QoS-aware routing protocol and CACP protocols, it is shown from system simulations that the proposed scheme can increase the system throughput and reduce both the dropping rate and the end-to-end delay. Therefore, TPAC is surely an effective QoS-guarantee protocol to provide for real-time traffic.

  10. Worm epidemics in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Nekovee, Maziar

    2007-06-01

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

  11. Ad-Hoc Queries over Document Collections - A Case Study

    NASA Astrophysics Data System (ADS)

    Löser, Alexander; Lutter, Steffen; Düssel, Patrick; Markl, Volker

    We discuss the novel problem of supporting analytical business intelligence queries over web-based textual content, e.g., BI-style reports based on 100.000's of documents from an ad-hoc web search result. Neither conventional search engines nor conventional Business Intelligence and ETL tools address this problem, which lies at the intersection of their capabilities. "Google Squared" or our system GOOLAP.info, are examples of these kinds of systems. They execute information extraction methods over one or several document collections at query time and integrate extracted records into a common view or tabular structure. Frequent extraction and object resolution failures cause incomplete records which could not be joined into a record answering the query. Our focus is the identification of join-reordering heuristics maximizing the size of complete records answering a structured query. With respect to given costs for document extraction we propose two novel join-operations: The multi-way CJ-operator joins records from multiple relationships extracted from a single document. The two-way join-operator DJ ensures data density by removing incomplete records from results. In a preliminary case study we observe that our join-reordering heuristics positively impact result size, record density and lower execution costs.

  12. An Ad-Hoc Adaptive Pilot Model for Pitch Axis Gross Acquisition Tasks

    NASA Technical Reports Server (NTRS)

    Hanson, Curtis E.

    2012-01-01

    An ad-hoc algorithm is presented for real-time adaptation of the well-known crossover pilot model and applied to pitch axis gross acquisition tasks in a generic fighter aircraft. Off-line tuning of the crossover model to human pilot data gathered in a fixed-based high fidelity simulation is first accomplished for a series of changes in aircraft dynamics to provide expected values for model parameters. It is shown that in most cases, for this application, the traditional crossover model can be reduced to a gain and a time delay. The ad-hoc adaptive pilot gain algorithm is shown to have desirable convergence properties for most types of changes in aircraft dynamics.

  13. Energy Efficient Probabilistic Broadcasting for Mobile Ad-Hoc Network

    NASA Astrophysics Data System (ADS)

    Kumar, Sumit; Mehfuz, Shabana

    2017-06-01

    In mobile ad-hoc network (MANETs) flooding method is used for broadcasting route request (RREQ) packet from one node to another node for route discovery. This is the simplest method of broadcasting of RREQ packets but it often results in broadcast storm problem, originating collisions and congestion of packets in the network. A probabilistic broadcasting is one of the widely used broadcasting scheme for route discovery in MANETs and provides solution for broadcasting storm problem. But it does not consider limited energy of the battery of the nodes. In this paper, a new energy efficient probabilistic broadcasting (EEPB) is proposed in which probability of broadcasting RREQs is calculated with respect to remaining energy of nodes. The analysis of simulation results clearly indicate that an EEPB route discovery scheme in ad-hoc on demand distance vector (AODV) can increase the network lifetime with a decrease in the average power consumption and RREQ packet overhead. It also decreases the number of dropped packets in the network, in comparison to other EEPB schemes like energy constraint gossip (ECG), energy aware gossip (EAG), energy based gossip (EBG) and network lifetime through energy efficient broadcast gossip (NEBG).

  14. Information Fusion in Ad hoc Wireless Sensor Networks for Aircraft Health Monitoring

    NASA Astrophysics Data System (ADS)

    Fragoulis, Nikos; Tsagaris, Vassilis; Anastassopoulos, Vassilis

    In this paper the use of an ad hoc wireless sensor network for implementing a structural health monitoring system is discussed. The network is consisted of sensors deployed throughout the aircraft. These sensors being in the form of a microelectronic chip and consisted of sensing, data processing and communicating components could be easily embedded in any mechanical aircraft component. The established sensor network, due to its ad hoc nature is easily scalable, allowing adding or removing any number of sensors. The position of the sensor nodes need not necessarily to be engineered or predetermined, giving this way the ability to be deployed in inaccessible points. Information collected from various sensors of different modalities throughout the aircraft is then fused in order to provide a more comprehensive image of the aircraft structural health. Sensor level fusion along with decision quality information is used, in order to enhance detection performance.

  15. A fault-tolerant small world topology control model in ad hoc networks for search and rescue

    NASA Astrophysics Data System (ADS)

    Tan, Mian; Fang, Ling; Wu, Yue; Zhang, Bo; Chang, Bowen; Holme, Petter; Zhao, Jing

    2018-02-01

    Due to their self-organized, multi-hop and distributed characteristics, ad hoc networks are useful in search and rescue. Topology control models need to be designed for energy-efficient, robust and fast communication in ad hoc networks. This paper proposes a topology control model which specializes for search and rescue-Compensation Small World-Repeated Game (CSWRG)-which integrates mobility models, constructing small world networks and a game-theoretic approach to the allocation of resources. Simulation results show that our mobility models can enhance the communication performance of the constructed small-world networks. Our strategy, based on repeated game, can suppress selfish behavior and compensate agents that encounter selfish or faulty neighbors. This model could be useful for the design of ad hoc communication networks.

  16. 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.

  17. Space-Time Processing for Tactical Mobile Ad Hoc Networks

    DTIC Science & Technology

    2007-08-01

    rates in mobile ad hoc networks. In addition, he has considered the design of a cross-layer multi-user resource allocation framework using a... framework for many-to-one communication. In this context, multiple nodes cooperate to transmit their packets simultaneously to a single node using multi...spatially multiplexed signals transmitted from multiple nodes. Our goal is to form a framework that activates different sets of communication links

  18. Space-Time Processing for Tactical Mobile Ad Hoc Networks

    DTIC Science & Technology

    2008-08-01

    vision for multiple concurrent communication settings, i.e., a many-to-many framework where multi-packet transmissions (MPTs) and multi-packet...modelling framework of capacity-delay tradeoffs We have introduced the first unified modeling framework for the computation of fundamental limits o We...dalities in wireless n twor i-packet modelling framework to account for the use of m lti-packet reception (MPR) f ad hoc networks with MPT under

  19. Dynamic autonomous routing technology for IP-based satellite ad hoc networks

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofei; Deng, Jing; Kostas, Theresa; Rajappan, Gowri

    2014-06-01

    IP-based routing for military LEO/MEO satellite ad hoc networks is very challenging due to network and traffic heterogeneity, network topology and traffic dynamics. In this paper, we describe a traffic priority-aware routing scheme for such networks, namely Dynamic Autonomous Routing Technology (DART) for satellite ad hoc networks. DART has a cross-layer design, and conducts routing and resource reservation concurrently for optimal performance in the fluid but predictable satellite ad hoc networks. DART ensures end-to-end data delivery with QoS assurances by only choosing routing paths that have sufficient resources, supporting different packet priority levels. In order to do so, DART incorporates several resource management and innovative routing mechanisms, which dynamically adapt to best fit the prevailing conditions. In particular, DART integrates a resource reservation mechanism to reserve network bandwidth resources; a proactive routing mechanism to set up non-overlapping spanning trees to segregate high priority traffic flows from lower priority flows so that the high priority flows do not face contention from low priority flows; a reactive routing mechanism to arbitrate resources between various traffic priorities when needed; a predictive routing mechanism to set up routes for scheduled missions and for anticipated topology changes for QoS assurance. We present simulation results showing the performance of DART. We have conducted these simulations using the Iridium constellation and trajectories as well as realistic military communications scenarios. The simulation results demonstrate DART's ability to discriminate between high-priority and low-priority traffic flows and ensure disparate QoS requirements of these traffic flows.

  20. Ad Hoc Supervision of General Practice Registrars as a "Community of Practice": Analysis, Interpretation and Re-Presentation

    ERIC Educational Resources Information Center

    Clement, T.; Brown, J.; Morrison, J.; Nestel, D.

    2016-01-01

    General practice registrars in Australia undertake most of their vocational training in accredited general practices. They typically see patients alone from the start of their community-based training and are expected to seek timely ad hoc support from their supervisor. Such ad hoc encounters are a mechanism for ensuring patient safety, but also…

  1. Modeling and optimization of Quality of Service routing in Mobile Ad hoc Networks

    NASA Astrophysics Data System (ADS)

    Rafsanjani, Marjan Kuchaki; Fatemidokht, Hamideh; Balas, Valentina Emilia

    2016-01-01

    Mobile ad hoc networks (MANETs) are a group of mobile nodes that are connected without using a fixed infrastructure. In these networks, nodes communicate with each other by forming a single-hop or multi-hop network. To design effective mobile ad hoc networks, it is important to evaluate the performance of multi-hop paths. In this paper, we present a mathematical model for a routing protocol under energy consumption and packet delivery ratio of multi-hop paths. In this model, we use geometric random graphs rather than random graphs. Our proposed model finds effective paths that minimize the energy consumption and maximizes the packet delivery ratio of the network. Validation of the mathematical model is performed through simulation.

  2. The 5th Meeting of the Ad Hoc Panel on Terminal Configured Vehicles

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A report of the fifth meeting of the NASA Research and Technology Advisory Council, Ad Hoc panel on Terminal Configured Vehicles is presented. Some of the following topics were discussed; (1) microwave landing systems; (2) whole word computer system status; (3) flight path angle control: (4) VTOL approaches and landing technology; and (5) simulation study in wind shear.

  3. Ad-Hoc Networks and the Mobile Application Security System (MASS)

    DTIC Science & Technology

    2006-01-01

    solution to this problem that addresses critical aspects of security in ad-hoc mobile application networks. This approach involves preventing unauthorized...modification of a mobile application , both by other applications and by hosts, and ensuring that mobile code is authentic and authorized. These...capabilities constitute the Mobile Application Security System (MASS). The MASS applies effective, robust security to mobile application -based systems

  4. Data management issues in mobile ad hoc networks

    PubMed Central

    HARA, Takahiro

    2017-01-01

    Research on mobile ad hoc networks (MANETs) has become a hot research topic since the middle 1990’s. Over the first decade, most research focused on networking techniques, ignoring data management issues. We, however, realized early the importance of data management in MANETs, and have been conducting studies in this area for 15 years. In this review, we summarize some key technical issues related to data management in MANETs, and the studies we have done in addressing these issues, which include placement of data replicas, update management, and query processing with security management. The techniques proposed in our studies have been designed with deep considerations of MANET features including network partitioning, node participation/disappearance, limited network bandwidth, and energy efficiency. Our studies published in early 2000’s have developed a new research field as data management in MANETs. Also, our recent studies are expected to be significant guidelines of new research directions. We conclude the review by discussing some future directions for research. PMID:28496052

  5. Data management issues in mobile ad hoc networks.

    PubMed

    Hara, Takahiro

    2017-01-01

    Research on mobile ad hoc networks (MANETs) has become a hot research topic since the middle 1990's. Over the first decade, most research focused on networking techniques, ignoring data management issues. We, however, realized early the importance of data management in MANETs, and have been conducting studies in this area for 15 years. In this review, we summarize some key technical issues related to data management in MANETs, and the studies we have done in addressing these issues, which include placement of data replicas, update management, and query processing with security management. The techniques proposed in our studies have been designed with deep considerations of MANET features including network partitioning, node participation/disappearance, limited network bandwidth, and energy efficiency. Our studies published in early 2000's have developed a new research field as data management in MANETs. Also, our recent studies are expected to be significant guidelines of new research directions. We conclude the review by discussing some future directions for research.

  6. T2AR: trust-aware ad-hoc routing protocol for MANET.

    PubMed

    Dhananjayan, Gayathri; Subbiah, Janakiraman

    2016-01-01

    Secure data transfer against the malicious attacks is an important issue in an infrastructure-less independent network called mobile ad-hoc network (MANET). Trust assurance between MANET nodes is the key parameter in the high-security provision under dynamic topology variations and open wireless constraints. But, the malicious behavior of nodes reduces the trust level of the nodes that leads to an insecure data delivery. The increase in malicious attacks causes the excessive energy consumption that leads to a reduction of network lifetime. The lack of positional information update of the nodes in ad-hoc on-demand vector (AODV) protocol during the connection establishment offers less trust level between the nodes. Hence, the trust rate computation using energy and mobility models and its update are the essential tasks for secure data delivery. This paper proposes a trust-aware ad-hoc routing (T2AR) protocol to improve the trust level between the nodes in MANET. The proposed method modifies the traditional AODV routing protocol with the constraints of trust rate, energy, mobility based malicious behavior prediction. The packet sequence ID matching from the log reports of neighbor nodes determine the trust rate that avoids the malicious report generation. Besides, the direct and indirect trust observation schemes utilization increases the trust level. Besides, the received signal strength indicator utilization determines the trusted node is within the communication range or not. The comparative analysis between the proposed T2AR with the existing methods such as TRUNCMAN, RBT, GR, FBR and DICOTIDS regarding the average end-to-end delay, throughput, false positives, packet delivery ratio shows the effectiveness of T2AR in the secure MANET environment design.

  7. Performance Analysis of Hierarchical Group Key Management Integrated with Adaptive Intrusion Detection in Mobile ad hoc Networks

    DTIC Science & Technology

    2016-04-05

    applications in wireless networks such as military battlefields, emergency response, mobile commerce , online gaming, and collaborative work are based on the...www.elsevier.com/locate/peva Performance analysis of hierarchical group key management integrated with adaptive intrusion detection in mobile ad hoc...Accepted 19 September 2010 Available online 26 September 2010 Keywords: Mobile ad hoc networks Intrusion detection Group communication systems Group

  8. Protocols for Detection and Removal of Wormholes for Secure Routing and Neighborhood Creation in Wireless Ad Hoc Networks

    ERIC Educational Resources Information Center

    Hayajneh, Thaier Saleh

    2009-01-01

    Wireless ad hoc networks are suitable and sometimes the only solution for several applications. Many applications, particularly those in military and critical civilian domains (such as battlefield surveillance and emergency rescue) require that ad hoc networks be secure and stable. In fact, security is one of the main barriers to the extensive use…

  9. HOW GAS-DYNAMIC FLARE MODELS POWERED BY PETSCHEK RECONNECTION DIFFER FROM THOSE WITH AD HOC ENERGY SOURCES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Longcope, D. W.; Klimchuk, J. A.

    Aspects of solar flare dynamics, such as chromospheric evaporation and flare light curves, have long been studied using one-dimensional models of plasma dynamics inside a static flare loop, subjected to some energy input. While extremely successful at explaining the observed characteristics of flares, all such models so far have specified energy input ad hoc, rather than deriving it self-consistently. There is broad consensus that flares are powered by magnetic energy released through reconnection. Recent work has generalized Petschek’s basic reconnection scenario, topological change followed by field line retraction and shock heating, to permit its inclusion in a one-dimensional flare loop model. Heremore » we compare the gas dynamics driven by retraction and shocking to those from more conventional static loop models energized by ad hoc source terms. We find significant differences during the first minute, when retraction leads to larger kinetic energies and produces higher densities at the loop top, while ad hoc heating tends to rarify the loop top. The loop-top density concentration is related to the slow magnetosonic shock, characteristic of Petschek’s model, but persists beyond the retraction phase occurring in the outflow jet. This offers an explanation for observed loop-top sources of X-ray and EUV emission, with advantages over that provided by ad hoc heating scenarios. The cooling phases of the two models are, however, notably similar to one another, suggesting that observations at that stage will yield little information on the nature of energy input.« less

  10. Work, Family, and Community: Summary Proceedings of an Ad Hoc Committee.

    ERIC Educational Resources Information Center

    Hayes, Cheryl D., Ed.

    These proceedings contain summaries of five working group discussions and a discussion of suggestions for future research from an ad hoc meeting on Work, Family, and Community (Fedruary 21-22, 1980) in Washington, D.C. The meeting had these objectives: (1) to identify salient policy and research issues associated with changing patterns of labor…

  11. Defense Acquisition and the Case of the Joint Capabilities Technology Demonstration Office: Ad Hoc Problem Solving as a Mechanism for Adaptive Change

    DTIC Science & Technology

    2013-04-01

    Capabilities Technology Demonstration Office: Ad Hoc Problem Solving as a Mechanism for Adaptive Change Kathryn Aten and John T. Dillard Naval...Defense Acquisition and the Case of the Joint Capabilities Technology Demonstration Office: Ad Hoc Problem Solving as a Mechanism for Adaptive Change...describes the preliminary analysis and findings of our study exploring what drives successful organizational adaptation in the context of technology

  12. A Survey on Trust Management for Mobile Ad Hoc Networks

    DTIC Science & Technology

    2011-11-01

    expects, trust is dangerous implying the possible betrayal of trust. In his comments on Lagerspetz’s book titled Trust: The Tacit Demand, Lahno [24...AODV Zouridaki et al. (2005 ) [79] (2006) [80] Secure routing Direct observation [79][80] Reputation by secondhand information [80] Packet dropping...areas of signal processing, wireless communications, sensor and mobile ad hoc networks. He is co-editor of the book Wireless Sensor Networks: Signal

  13. An Optimal CDS Construction Algorithm with Activity Scheduling in Ad Hoc Networks

    PubMed Central

    Penumalli, Chakradhar; Palanichamy, Yogesh

    2015-01-01

    A new energy efficient optimal Connected Dominating Set (CDS) algorithm with activity scheduling for mobile ad hoc networks (MANETs) is proposed. This algorithm achieves energy efficiency by minimizing the Broadcast Storm Problem [BSP] and at the same time considering the node's remaining energy. The Connected Dominating Set is widely used as a virtual backbone or spine in mobile ad hoc networks [MANETs] or Wireless Sensor Networks [WSN]. The CDS of a graph representing a network has a significant impact on an efficient design of routing protocol in wireless networks. Here the CDS is a distributed algorithm with activity scheduling based on unit disk graph [UDG]. The node's mobility and residual energy (RE) are considered as parameters in the construction of stable optimal energy efficient CDS. The performance is evaluated at various node densities, various transmission ranges, and mobility rates. The theoretical analysis and simulation results of this algorithm are also presented which yield better results. PMID:26221627

  14. On knowledge transfer management as a learning process for ad hoc teams

    NASA Astrophysics Data System (ADS)

    Iliescu, D.

    2017-08-01

    Knowledge management represents an emerging domain becoming more and more important. Concepts like knowledge codification and personalisation, knowledge life-cycle, social and technological dimensions, knowledge transfer and learning management are integral parts. Focus goes here in the process of knowledge transfer for the case of ad hoc teams. The social dimension of knowledge transfer plays an important role. No single individual actors involved in the process, but a collective one, representing the organisation. It is critically important for knowledge to be managed from the life-cycle point of view. A complex communication network needs to be in place to supports the process of knowledge transfer. Two particular concepts, the bridge tie and transactive memory, would eventually enhance the communication. The paper focuses on an informational communication platform supporting the collaborative work on knowledge transfer. The platform facilitates the creation of a topic language to be used in knowledge modelling, storage and reuse, by the ad hoc teams.

  15. Scalable Architecture for Multihop Wireless ad Hoc Networks

    NASA Technical Reports Server (NTRS)

    Arabshahi, Payman; Gray, Andrew; Okino, Clayton; Yan, Tsun-Yee

    2004-01-01

    A scalable architecture for wireless digital data and voice communications via ad hoc networks has been proposed. Although the details of the architecture and of its implementation in hardware and software have yet to be developed, the broad outlines of the architecture are fairly clear: This architecture departs from current commercial wireless communication architectures, which are characterized by low effective bandwidth per user and are not well suited to low-cost, rapid scaling in large metropolitan areas. This architecture is inspired by a vision more akin to that of more than two dozen noncommercial community wireless networking organizations established by volunteers in North America and several European countries.

  16. Defense Acquisition and the Case of the Joint Capabilities Technology Demonstration Office: Ad Hoc Problem Solving as a Mechanism for Adaptive Change

    DTIC Science & Technology

    2013-10-01

    pmlkploba=obmloq=pbofbp= Defense Acquisition and the Case of the Joint Capabilities Technology Demonstration Office: Ad Hoc Problem Solving as a...of the Joint Capabilities Technology Demonstration Office: Ad Hoc Problem Solving as a Mechanism for Adaptive Change 5a. CONTRACT NUMBER 5b. GRANT...findings of our study exploring what drives successful organizational adaptation in the context of technology transition and acquisition within the

  17. A Survey on Trust Management for Mobile Ad Hoc Networks

    DTIC Science & Technology

    2010-07-01

    betrayal of trust. In his comments on Lagerspetz’s book titled Trust: The Tacit Demand, Lahno [24] describes the author’s view on trust as a moral...extension of AODV Zouridaki et al. (2005 ) [79] (2006) [80] Secure routing Direct observation [79][80] Reputation by secondhand information [80...the broad areas of signal processing, wireless communications, sensor and mobile ad hoc networks. He is co-editor of the book Wireless Sensor Networks

  18. Power-Aware Intrusion Detection in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Şen, Sevil; Clark, John A.; Tapiador, Juan E.

    Mobile ad hoc networks (MANETs) are a highly promising new form of networking. However they are more vulnerable to attacks than wired networks. In addition, conventional intrusion detection systems (IDS) are ineffective and inefficient for highly dynamic and resource-constrained environments. Achieving an effective operational MANET requires tradeoffs to be made between functional and non-functional criteria. In this paper we show how Genetic Programming (GP) together with a Multi-Objective Evolutionary Algorithm (MOEA) can be used to synthesise intrusion detection programs that make optimal tradeoffs between security criteria and the power they consume.

  19. Design of free patterns of nanocrystals with ad hoc features via templated dewetting

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aouassa, M.; Berbezier, I.; Favre, L.

    Design of monodisperse ultra-small nanocrystals (NCs) into large scale patterns with ad hoc features is demonstrated. The process makes use of solid state dewetting of a thin film templated through alloy liquid metal ion source focused ion beam (LMIS-FIB) nanopatterning. The solid state dewetting initiated at the edges of the patterns controllably creates the ordering of NCs with ad hoc placement and periodicity. The NC size is tuned by varying the nominal thickness of the film while their position results from the association of film retraction from the edges of the lay out and Rayleigh-like instability. The use of ultra-highmore » resolution LMIS-FIB enables to produce monocrystalline NCs with size, periodicity, and placement tunable as well. It provides routes for the free design of nanostructures for generic applications in nanoelectronics.« less

  20. The impact of brief team communication, leadership and team behavior training on ad hoc team performance in trauma care settings.

    PubMed

    Roberts, Nicole K; Williams, Reed G; Schwind, Cathy J; Sutyak, John A; McDowell, Christopher; Griffen, David; Wall, Jarrod; Sanfey, Hilary; Chestnut, Audra; Meier, Andreas H; Wohltmann, Christopher; Clark, Ted R; Wetter, Nathan

    2014-02-01

    Communication breakdowns and care coordination problems often cause preventable adverse patient care events, which can be especially acute in the trauma setting, in which ad hoc teams have little time for advanced planning. Existing teamwork curricula do not address the particular issues associated with ad hoc emergency teams providing trauma care. Ad hoc trauma teams completed a preinstruction simulated trauma encounter and were provided with instruction on appropriate team behaviors and team communication. Teams completed a postinstruction simulated trauma encounter immediately afterward and 3 weeks later, then completed a questionnaire. Blinded raters rated videotapes of the simulations. Participants expressed high levels of satisfaction and intent to change practice after the intervention. Participants changed teamwork and communication behavior on the posttest, and changes were sustained after a 3-week interval, though there was some loss of retention. Brief training exercises can change teamwork and communication behaviors on ad hoc trauma teams. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Ad hoc categories and false memories: Memory illusions for categories created on-the-spot.

    PubMed

    Soro, Jerônimo C; Ferreira, Mário B; Semin, Gün R; Mata, André; Carneiro, Paula

    2017-11-01

    Three experiments were designed to test whether experimentally created ad hoc associative networks evoke false memories. We used the DRM (Deese, Roediger, McDermott) paradigm with lists of ad hoc categories composed of exemplars aggregated toward specific goals (e.g., going for a picnic) that do not share any consistent set of features. Experiment 1 revealed considerable levels of false recognitions of critical words from ad hoc categories. False recognitions occurred even when the lists were presented without an organizing theme (i.e., the category's label). Experiments 1 and 2 tested whether (a) the ease of identifying the categories' themes, and (b) the lists' backward associative strength could be driving the effect. List identifiability did not correlate with false recognition, and the effect remained even when backward associative strength was controlled for. Experiment 3 manipulated the distractor items in the recognition task to address the hypothesis that the salience of unrelated items could be facilitating the occurrence of the phenomenon. The effect remained when controlling for this source of facilitation. These results have implications for assumptions made by theories of false memories, namely the preexistence of associations in the activation-monitoring framework and the central role of gist extraction in fuzzy-trace theory, while providing evidence of the occurrence of false memories for more dynamic and context-dependent knowledge structures. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  2. Ad Hoc Selection of Voice over Internet Streams

    NASA Technical Reports Server (NTRS)

    Macha, Mitchell G. (Inventor); Bullock, John T. (Inventor)

    2014-01-01

    A method and apparatus for a communication system technique involving ad hoc selection of at least two audio streams is provided. Each of the at least two audio streams is a packetized version of an audio source. A data connection exists between a server and a client where a transport protocol actively propagates the at least two audio streams from the server to the client. Furthermore, software instructions executable on the client indicate a presence of the at least two audio streams, allow selection of at least one of the at least two audio streams, and direct the selected at least one of the at least two audio streams for audio playback.

  3. Ad Hoc Selection of Voice over Internet Streams

    NASA Technical Reports Server (NTRS)

    Macha, Mitchell G. (Inventor); Bullock, John T. (Inventor)

    2008-01-01

    A method and apparatus for a communication system technique involving ad hoc selection of at least two audio streams is provided. Each of the at least two audio streams is a packetized version of an audio source. A data connection exists between a server and a client where a transport protocol actively propagates the at least two audio streams from the server to the client. Furthermore, software instructions executable on the client indicate a presence of the at least two audio streams, allow selection of at least one of the at least two audio streams, and direct the selected at least one of the at least two audio streams for audio playback.

  4. Dynamic fair node spectrum allocation for ad hoc networks using random matrices

    NASA Astrophysics Data System (ADS)

    Rahmes, Mark; Lemieux, George; Chester, Dave; Sonnenberg, Jerry

    2015-05-01

    Dynamic Spectrum Access (DSA) is widely seen as a solution to the problem of limited spectrum, because of its ability to adapt the operating frequency of a radio. Mobile Ad Hoc Networks (MANETs) can extend high-capacity mobile communications over large areas where fixed and tethered-mobile systems are not available. In one use case with high potential impact, cognitive radio employs spectrum sensing to facilitate the identification of allocated frequencies not currently accessed by their primary users. Primary users own the rights to radiate at a specific frequency and geographic location, while secondary users opportunistically attempt to radiate at a specific frequency when the primary user is not using it. We populate a spatial radio environment map (REM) database with known information that can be leveraged in an ad hoc network to facilitate fair path use of the DSA-discovered links. Utilization of high-resolution geospatial data layers in RF propagation analysis is directly applicable. Random matrix theory (RMT) is useful in simulating network layer usage in nodes by a Wishart adjacency matrix. We use the Dijkstra algorithm for discovering ad hoc network node connection patterns. We present a method for analysts to dynamically allocate node-node path and link resources using fair division. User allocation of limited resources as a function of time must be dynamic and based on system fairness policies. The context of fair means that first available request for an asset is not envied as long as it is not yet allocated or tasked in order to prevent cycling of the system. This solution may also save money by offering a Pareto efficient repeatable process. We use a water fill queue algorithm to include Shapley value marginal contributions for allocation.

  5. Cross-layer model design in wireless ad hoc networks for the Internet of Things.

    PubMed

    Yang, Xin; Wang, Ling; Xie, Jian; Zhang, Zhaolin

    2018-01-01

    Wireless ad hoc networks can experience extreme fluctuations in transmission traffic in the Internet of Things, which is widely used today. Currently, the most crucial issues requiring attention for wireless ad hoc networks are making the best use of low traffic periods, reducing congestion during high traffic periods, and improving transmission performance. To solve these problems, the present paper proposes a novel cross-layer transmission model based on decentralized coded caching in the physical layer and a content division multiplexing scheme in the media access control layer. Simulation results demonstrate that the proposed model effectively addresses these issues by substantially increasing the throughput and successful transmission rate compared to existing protocols without a negative influence on delay, particularly for large scale networks under conditions of highly contrasting high and low traffic periods.

  6. Cross-layer model design in wireless ad hoc networks for the Internet of Things

    PubMed Central

    Wang, Ling; Xie, Jian; Zhang, Zhaolin

    2018-01-01

    Wireless ad hoc networks can experience extreme fluctuations in transmission traffic in the Internet of Things, which is widely used today. Currently, the most crucial issues requiring attention for wireless ad hoc networks are making the best use of low traffic periods, reducing congestion during high traffic periods, and improving transmission performance. To solve these problems, the present paper proposes a novel cross-layer transmission model based on decentralized coded caching in the physical layer and a content division multiplexing scheme in the media access control layer. Simulation results demonstrate that the proposed model effectively addresses these issues by substantially increasing the throughput and successful transmission rate compared to existing protocols without a negative influence on delay, particularly for large scale networks under conditions of highly contrasting high and low traffic periods. PMID:29734355

  7. A game-theoretic approach to optimize ad hoc networks inspired by small-world network topology

    NASA Astrophysics Data System (ADS)

    Tan, Mian; Yang, Tinghong; Chen, Xing; Yang, Gang; Zhu, Guoqing; Holme, Petter; Zhao, Jing

    2018-03-01

    Nodes in ad hoc networks are connected in a self-organized manner. Limited communication radius makes information transmit in multi-hop mode, and each forwarding needs to consume the energy of nodes. Insufficient communication radius or exhaustion of energy may cause the absence of some relay nodes and links, further breaking network connectivity. On the other hand, nodes in the network may refuse to cooperate due to objective faulty or personal selfish, hindering regular communication in the network. This paper proposes a model called Repeated Game in Small World Networks (RGSWN). In this model, we first construct ad hoc networks with small-world feature by forming "communication shortcuts" between multiple-radio nodes. Small characteristic path length reduces average forwarding times in networks; meanwhile high clustering coefficient enhances network robustness. Such networks still maintain relative low global power consumption, which is beneficial to extend the network survival time. Then we use MTTFT strategy (Mend-Tolerance Tit-for-Tat) for repeated game as a rule for the interactions between neighbors in the small-world networks. Compared with other five strategies of repeated game, this strategy not only punishes the nodes' selfishness more reasonably, but also has the best tolerance to the network failure. This work is insightful for designing an efficient and robust ad hoc network.

  8. Forming an ad-hoc nearby storage, based on IKAROS and social networking services

    NASA Astrophysics Data System (ADS)

    Filippidis, Christos; Cotronis, Yiannis; Markou, Christos

    2014-06-01

    We present an ad-hoc "nearby" storage, based on IKAROS and social networking services, such as Facebook. By design, IKAROS is capable to increase or decrease the number of nodes of the I/O system instance on the fly, without bringing everything down or losing data. IKAROS is capable to decide the file partition distribution schema, by taking on account requests from the user or an application, as well as a domain or a Virtual Organization policy. In this way, it is possible to form multiple instances of smaller capacity higher bandwidth storage utilities capable to respond in an ad-hoc manner. This approach, focusing on flexibility, can scale both up and down and so can provide more cost effective infrastructures for both large scale and smaller size systems. A set of experiments is performed comparing IKAROS with PVFS2 by using multiple clients requests under HPC IOR benchmark and MPICH2.

  9. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks

    PubMed Central

    Mezher, Ahmad Mohamad; Igartua, Mónica Aguilar; de la Cruz Llopis, Luis J.; Segarra, Esteve Pallarès; Tripp-Barba, Carolina; Urquiza-Aguiar, Luis; Forné, Jordi; Gargallo, Emilio Sanvicente

    2015-01-01

    The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc.) could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers) rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs) has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic.Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs. PMID:25897496

  10. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks.

    PubMed

    Mezher, Ahmad Mohamad; Igartua, Mónica Aguilar; de la Cruz Llopis, Luis J; Pallarès Segarra, Esteve; Tripp-Barba, Carolina; Urquiza-Aguiar, Luis; Forné, Jordi; Sanvicente Gargallo, Emilio

    2015-04-17

    The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc.) could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers) rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs) has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic. Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs.

  11. Specialist availability in emergencies: contributions of response times and the use of ad hoc coverage in New York State.

    PubMed

    Rabin, Elaine; Patrick, Lisa

    2016-04-01

    Nationwide, hospitals struggle to maintain specialist on-call coverage for emergencies. We seek to further understand the issue by examining reliability of scheduled coverage and the role of ad hoc coverage when none is scheduled. An anonymous electronic survey of all emergency department (ED) directors of a large state. Overall and for 10 specialties, respondents were asked to estimate on-call coverage extent and "reliability" (frequency of emergency response in a clinically useful time frame: 2 hours), and use and effect of ad hoc emergency coverage to fill gaps. Descriptive statistics were performed using Fisher exact and Wilcoxon sign rank tests for significance. Contact information was obtained for 125 of 167 ED directors. Sixty responded (48%), representing 36% of EDs. Forty-six percent reported full on-call coverage scheduled for all specialties. Forty-six percent reported consistent reliability. Coverage and reliability were strongly related (P<.01; 33% reported both), and larger ED volume correlated with both (P<.01). Ninety percent of hospitals that had gaps in either employed ad hoc coverage, significantly improving coverage for 8 of 10 specialties. For all but 1 specialty, more than 20% of hospitals reported that specialists are "Never", "Rarely" or "Sometimes" reliable (more than 50% for cardiovascular surgery, hand surgery and ophthalmology). Significant holes in scheduled on-call specialist coverage are compounded by frequent unreliability of on-call specialists, but partially ameliorated by ad hoc specialist coverage. Regionalization may help because a 2-tiered system may exist: larger hospitals have more complete, reliable coverage. Better understanding of specialists' willingness to treat emergencies ad hoc without taking formal call will suggest additional remedies. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Smart border: ad-hoc wireless sensor networks for border surveillance

    NASA Astrophysics Data System (ADS)

    He, Jun; Fallahi, Mahmoud; Norwood, Robert A.; Peyghambarian, Nasser

    2011-06-01

    Wireless sensor networks have been proposed as promising candidates to provide automated monitoring, target tracking, and intrusion detection for border surveillance. In this paper, we demonstrate an ad-hoc wireless sensor network system for border surveillance. The network consists of heterogeneously autonomous sensor nodes that distributively cooperate with each other to enable a smart border in remote areas. This paper also presents energy-aware and sleeping algorithms designed to maximize the operating lifetime of the deployed sensor network. Lessons learned in building the network and important findings from field experiments are shared in the paper.

  13. Spontaneous ad hoc mobile cloud computing network.

    PubMed

    Lacuesta, Raquel; Lloret, Jaime; Sendra, Sandra; Peñalver, Lourdes

    2014-01-01

    Cloud computing helps users and companies to share computing resources instead of having local servers or personal devices to handle the applications. Smart devices are becoming one of the main information processing devices. Their computing features are reaching levels that let them create a mobile cloud computing network. But sometimes they are not able to create it and collaborate actively in the cloud because it is difficult for them to build easily a spontaneous network and configure its parameters. For this reason, in this paper, we are going to present the design and deployment of a spontaneous ad hoc mobile cloud computing network. In order to perform it, we have developed a trusted algorithm that is able to manage the activity of the nodes when they join and leave the network. The paper shows the network procedures and classes that have been designed. Our simulation results using Castalia show that our proposal presents a good efficiency and network performance even by using high number of nodes.

  14. On service differentiation in mobile Ad Hoc networks.

    PubMed

    Zhang, Shun-liang; Ye, Cheng-qing

    2004-09-01

    A network model is proposed to support service differentiation for mobile Ad Hoc networks by combining a fully distributed admission control approach and the DIFS based differentiation mechanism of IEEE802.11. It can provide different kinds of QoS (Quality of Service) for various applications. Admission controllers determine a committed bandwidth based on the reserved bandwidth of flows and the source utilization of networks. Packets are marked when entering into networks by markers according to the committed rate. By the mark in the packet header, intermediate nodes handle the received packets in different manners to provide applications with the QoS corresponding to the pre-negotiated profile. Extensive simulation experiments showed that the proposed mechanism can provide QoS guarantee to assured service traffic and increase the channel utilization of networks.

  15. An artificial immune system approach with secondary response for misbehavior detection in mobile ad hoc networks.

    PubMed

    Sarafijanović, Slavisa; Le Boudec, Jean-Yves

    2005-09-01

    In mobile ad hoc networks, nodes act both as terminals and information relays, and they participate in a common routing protocol, such as dynamic source routing (DSR). The network is vulnerable to routing misbehavior, due to faulty or malicious nodes. Misbehavior detection systems aim at removing this vulnerability. In this paper, we investigate the use of an artificial immune system (AIS) to detect node misbehavior in a mobile ad hoc network using DSR. The system is inspired by the natural immune system (IS) of vertebrates. Our goal is to build a system that, like its natural counterpart, automatically learns, and detects new misbehavior. We describe our solution for the classification task of the AIS; it employs negative selection and clonal selection, the algorithms for learning and adaptation used by the natural IS. We define how we map the natural IS concepts such as self, antigen, and antibody to a mobile ad hoc network and give the resulting algorithm for classifying nodes as misbehaving. We implemented the system in the network simulator Glomosim; we present detection results and discuss how the system parameters affect the performance of primary and secondary response. Further steps will extend the design by using an analogy to the innate system, danger signal, and memory cells.

  16. The Use of English as Ad Hoc Institutional Standard in the Belgian Asylum Interview

    ERIC Educational Resources Information Center

    Maryns, Katrijn

    2017-01-01

    In institutional settings of globalization, labelled languages are generally preferred over multilingual repertoires and mobile language resources. Drawing on linguistic-ethnographic analysis of the way English is treated as an invariable "ad hoc" idiom in the Belgian asylum interview, this article demonstrates how institutional measures…

  17. Assessing Clinical Microbiology Practice Guidelines: American Society for Microbiology Ad Hoc Committee on Evidence-Based Laboratory Medicine Practice Guidelines Assessment.

    PubMed

    Nachamkin, Irving; Kirn, Thomas J; Westblade, Lars F; Humphries, Romney

    2017-11-01

    As part of the American Society for Microbiology (ASM) Evidence-Based Laboratory Medicine Practice Guidelines Committee of the Professional Practice Committee, an ad hoc committee was formed in 2014 to assess guidelines published by the committee using an assessment tool, Appraisal of Guidelines for Research Evaluation II (AGREE II). The AGREE II assessment helps reviewers determine whether published guidelines are robust, transparent, and clear in presenting practice recommendations in a standardized manner. Identifying strengths and weaknesses of practice guidelines by ad hoc assessments helps with improving future guidelines through the participation of key stakeholders. This minireview describes the development of the ad hoc committee and results from their review of several ASM best practices guidelines and a non-ASM practice guideline from the Emergency Nurses Association. Copyright © 2017 American Society for Microbiology.

  18. Assessing Clinical Microbiology Practice Guidelines: American Society for Microbiology Ad Hoc Committee on Evidence-Based Laboratory Medicine Practice Guidelines Assessment

    PubMed Central

    Kirn, Thomas J.; Westblade, Lars F.; Humphries, Romney

    2017-01-01

    ABSTRACT As part of the American Society for Microbiology (ASM) Evidence-Based Laboratory Medicine Practice Guidelines Committee of the Professional Practice Committee, an ad hoc committee was formed in 2014 to assess guidelines published by the committee using an assessment tool, Appraisal of Guidelines for Research Evaluation II (AGREE II). The AGREE II assessment helps reviewers determine whether published guidelines are robust, transparent, and clear in presenting practice recommendations in a standardized manner. Identifying strengths and weaknesses of practice guidelines by ad hoc assessments helps with improving future guidelines through the participation of key stakeholders. This minireview describes the development of the ad hoc committee and results from their review of several ASM best practices guidelines and a non-ASM practice guideline from the Emergency Nurses Association. PMID:28835476

  19. Greedy data transportation scheme with hard packet deadlines for wireless ad hoc networks.

    PubMed

    Lee, HyungJune

    2014-01-01

    We present a greedy data transportation scheme with hard packet deadlines in ad hoc sensor networks of stationary nodes and multiple mobile nodes with scheduled trajectory path and arrival time. In the proposed routing strategy, each stationary ad hoc node en route decides whether to relay a shortest-path stationary node toward destination or a passing-by mobile node that will carry closer to destination. We aim to utilize mobile nodes to minimize the total routing cost as far as the selected route can satisfy the end-to-end packet deadline. We evaluate our proposed routing algorithm in terms of routing cost, packet delivery ratio, packet delivery time, and usability of mobile nodes based on network level simulations. Simulation results show that our proposed algorithm fully exploits the remaining time till packet deadline to turn into networking benefits of reducing the overall routing cost and improving packet delivery performance. Also, we demonstrate that the routing scheme guarantees packet delivery with hard deadlines, contributing to QoS improvement in various network services.

  20. Greedy Data Transportation Scheme with Hard Packet Deadlines for Wireless Ad Hoc Networks

    PubMed Central

    Lee, HyungJune

    2014-01-01

    We present a greedy data transportation scheme with hard packet deadlines in ad hoc sensor networks of stationary nodes and multiple mobile nodes with scheduled trajectory path and arrival time. In the proposed routing strategy, each stationary ad hoc node en route decides whether to relay a shortest-path stationary node toward destination or a passing-by mobile node that will carry closer to destination. We aim to utilize mobile nodes to minimize the total routing cost as far as the selected route can satisfy the end-to-end packet deadline. We evaluate our proposed routing algorithm in terms of routing cost, packet delivery ratio, packet delivery time, and usability of mobile nodes based on network level simulations. Simulation results show that our proposed algorithm fully exploits the remaining time till packet deadline to turn into networking benefits of reducing the overall routing cost and improving packet delivery performance. Also, we demonstrate that the routing scheme guarantees packet delivery with hard deadlines, contributing to QoS improvement in various network services. PMID:25258736

  1. Adaptive Reliable Routing Protocol Using Combined Link Stability Estimation for Mobile Ad hoc Networks

    NASA Astrophysics Data System (ADS)

    Vadivel, R.; Bhaskaran, V. Murali

    2010-10-01

    The main reason for packet loss in ad hoc networks is the link failure or node failure. In order to increase the path stability, it is essential to distinguish and moderate the failures. By knowing individual link stability along a path, path stability can be identified. In this paper, we develop an adaptive reliable routing protocol using combined link stability estimation for mobile ad hoc networks. The main objective of this protocol is to determine a Quality of Service (QoS) path along with prolonging the network life time and to reduce the packet loss. We calculate a combined metric for a path based on the parameters Link Expiration Time, Node Remaining Energy and Node Velocity and received signal strength to predict the link stability or lifetime. Then, a bypass route is established to retransmit the lost data, when a link failure occurs. By simulation results, we show that the proposed reliable routing protocol achieves high delivery ratio with reduced delay and packet drop.

  2. A multihop key agreement scheme for wireless ad hoc networks based on channel characteristics.

    PubMed

    Hao, Zhuo; Zhong, Sheng; Yu, Nenghai

    2013-01-01

    A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM) adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks.

  3. A Multihop Key Agreement Scheme for Wireless Ad Hoc Networks Based on Channel Characteristics

    PubMed Central

    Yu, Nenghai

    2013-01-01

    A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM) adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks. PMID:23766725

  4. Stochastic does not equal ad hoc. [theories of lunar origin

    NASA Technical Reports Server (NTRS)

    Hartmann, W. K.

    1984-01-01

    Some classes of influential events in solar system history are class-predictable but not event-predictable. Theories of lunar origin should not ignore class-predictable stochastic events. Impacts and close encounters with large objects during planet formation are class-predictable. These stochastic events, such as large impacts that triggered ejection of Earth-mantle material into a circum-Earth cloud, should not be rejected as ad hoc. A way to deal with such events scientifically is to investigate their consequences; if it can be shown that they might produce the Moon, they become viable concepts in theories of lunar origin.

  5. Ad hoc committee on global climate issues: Annual report

    USGS Publications Warehouse

    Gerhard, L.C.; Hanson, B.M.B.

    2000-01-01

    The AAPG Ad Hoc Committee on Global Climate Issues has studied the supposition of human-induced climate change since the committee's inception in January 1998. This paper details the progress and findings of the committee through June 1999. At that time there had been essentially no geologic input into the global climate change debate. The following statements reflect the current state of climate knowledge from the geologic perspective as interpreted by the majority of the committee membership. The committee recognizes that new data could change its conclusions. The earth's climate is constantly changing owing to natural variability in earth processes. Natural climate variability over recent geological time is greater than reasonable estimates of potential human-induced greenhouse gas changes. Because no tool is available to test the supposition of human-induced climate change and the range of natural variability is so great, there is no discernible human influence on global climate at this time.

  6. Intelligent self-organization methods for wireless ad hoc sensor networks based on limited resources

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2006-05-01

    A wireless ad hoc sensor network (WSN) is a configuration for area surveillance that affords rapid, flexible deployment in arbitrary threat environments. There is no infrastructure support and sensor nodes communicate with each other only when they are in transmission range. To a greater degree than the terminals found in mobile ad hoc networks (MANETs) for communications, sensor nodes are resource-constrained, with limited computational processing, bandwidth, memory, and power, and are typically unattended once in operation. Consequently, the level of information exchange among nodes, to support any complex adaptive algorithms to establish network connectivity and optimize throughput, not only deplete those limited resources and creates high overhead in narrowband communications, but also increase network vulnerability to eavesdropping by malicious nodes. Cooperation among nodes, critical to the mission of sensor networks, can thus be disrupted by the inappropriate choice of the method for self-organization. Recent published contributions to the self-configuration of ad hoc sensor networks, e.g., self-organizing mapping and swarm intelligence techniques, have been based on the adaptive control of the cross-layer interactions found in MANET protocols to achieve one or more performance objectives: connectivity, intrusion resistance, power control, throughput, and delay. However, few studies have examined the performance of these algorithms when implemented with the limited resources of WSNs. In this paper, self-organization algorithms for the initiation, operation and maintenance of a network topology from a collection of wireless sensor nodes are proposed that improve the performance metrics significant to WSNs. The intelligent algorithm approach emphasizes low computational complexity, energy efficiency and robust adaptation to change, allowing distributed implementation with the actual limited resources of the cooperative nodes of the network. Extensions of the

  7. Integrated Social and Quality of Service Trust Management of Mobile Groups in Ad Hoc Networks

    DTIC Science & Technology

    2013-01-01

    high resiliency to malicious attacks and misbehaving nodes. Keywords—trust management; mobile ad hoc networks; QoS trust; social trust; trust...paper we address an importance issue of trust management protocol design for MANETs: trust bias minimization despite misbehaving nodes performing

  8. Topology for efficient information dissemination in ad-hoc networking

    NASA Technical Reports Server (NTRS)

    Jennings, E.; Okino, C. M.

    2002-01-01

    In this paper, we explore the information dissemination problem in ad-hoc wirless networks. First, we analyze the probability of successful broadcast, assuming: the nodes are uniformly distributed, the available area has a lower bould relative to the total number of nodes, and there is zero knowledge of the overall topology of the network. By showing that the probability of such events is small, we are motivated to extract good graph topologies to minimize the overall transmissions. Three algorithms are used to generate topologies of the network with guaranteed connectivity. These are the minimum radius graph, the relative neighborhood graph and the minimum spanning tree. Our simulation shows that the relative neighborhood graph has certain good graph properties, which makes it suitable for efficient information dissemination.

  9. Spontaneous Ad Hoc Mobile Cloud Computing Network

    PubMed Central

    Lacuesta, Raquel; Sendra, Sandra; Peñalver, Lourdes

    2014-01-01

    Cloud computing helps users and companies to share computing resources instead of having local servers or personal devices to handle the applications. Smart devices are becoming one of the main information processing devices. Their computing features are reaching levels that let them create a mobile cloud computing network. But sometimes they are not able to create it and collaborate actively in the cloud because it is difficult for them to build easily a spontaneous network and configure its parameters. For this reason, in this paper, we are going to present the design and deployment of a spontaneous ad hoc mobile cloud computing network. In order to perform it, we have developed a trusted algorithm that is able to manage the activity of the nodes when they join and leave the network. The paper shows the network procedures and classes that have been designed. Our simulation results using Castalia show that our proposal presents a good efficiency and network performance even by using high number of nodes. PMID:25202715

  10. Analytical Models of Cross-Layer Protocol Optimization in Real-Time Wireless Sensor Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    The real-time interactions among the nodes of a wireless sensor network (WSN) to cooperatively process data from multiple sensors are modeled. Quality-of-service (QoS) metrics are associated with the quality of fused information: throughput, delay, packet error rate, etc. Multivariate point process (MVPP) models of discrete random events in WSNs establish stochastic characteristics of optimal cross-layer protocols. Discrete-event, cross-layer interactions in mobile ad hoc network (MANET) protocols have been modeled using a set of concatenated design parameters and associated resource levels by the MVPPs. Characterization of the "best" cross-layer designs for a MANET is formulated by applying the general theory of martingale representations to controlled MVPPs. Performance is described in terms of concatenated protocol parameters and controlled through conditional rates of the MVPPs. Modeling limitations to determination of closed-form solutions versus explicit iterative solutions for ad hoc WSN controls are examined.

  11. A secure 3-way routing protocols for intermittently connected mobile ad hoc networks.

    PubMed

    Sekaran, Ramesh; Parasuraman, Ganesh Kumar

    2014-01-01

    The mobile ad hoc network may be partially connected or it may be disconnected in nature and these forms of networks are termed intermittently connected mobile ad hoc network (ICMANET). The routing in such disconnected network is commonly an arduous task. Many routing protocols have been proposed for routing in ICMANET since decades. The routing techniques in existence for ICMANET are, namely, flooding, epidemic, probabilistic, copy case, spray and wait, and so forth. These techniques achieve an effective routing with minimum latency, higher delivery ratio, lesser overhead, and so forth. Though these techniques generate effective results, in this paper, we propose novel routing algorithms grounded on agent and cryptographic techniques, namely, location dissemination service (LoDiS) routing with agent AES, A-LoDiS with agent AES routing, and B-LoDiS with agent AES routing, ensuring optimal results with respect to various network routing parameters. The algorithm along with efficient routing ensures higher degree of security. The security level is cited testing with respect to possibility of malicious nodes into the network. This paper also aids, with the comparative results of proposed algorithms, for secure routing in ICMANET.

  12. A Secure 3-Way Routing Protocols for Intermittently Connected Mobile Ad Hoc Networks

    PubMed Central

    Parasuraman, Ganesh Kumar

    2014-01-01

    The mobile ad hoc network may be partially connected or it may be disconnected in nature and these forms of networks are termed intermittently connected mobile ad hoc network (ICMANET). The routing in such disconnected network is commonly an arduous task. Many routing protocols have been proposed for routing in ICMANET since decades. The routing techniques in existence for ICMANET are, namely, flooding, epidemic, probabilistic, copy case, spray and wait, and so forth. These techniques achieve an effective routing with minimum latency, higher delivery ratio, lesser overhead, and so forth. Though these techniques generate effective results, in this paper, we propose novel routing algorithms grounded on agent and cryptographic techniques, namely, location dissemination service (LoDiS) routing with agent AES, A-LoDiS with agent AES routing, and B-LoDiS with agent AES routing, ensuring optimal results with respect to various network routing parameters. The algorithm along with efficient routing ensures higher degree of security. The security level is cited testing with respect to possibility of malicious nodes into the network. This paper also aids, with the comparative results of proposed algorithms, for secure routing in ICMANET. PMID:25136697

  13. An extended smart utilization medium access control (ESU-MAC) protocol for ad hoc wireless systems

    NASA Astrophysics Data System (ADS)

    Vashishtha, Jyoti; Sinha, Aakash

    2006-05-01

    The demand for spontaneous setup of a wireless communication system has increased in recent years for areas like battlefield, disaster relief operations etc., where a pre-deployment of network infrastructure is difficult or unavailable. A mobile ad-hoc network (MANET) is a promising solution, but poses a lot of challenges for all the design layers, specifically medium access control (MAC) layer. Recent existing works have used the concepts of multi-channel and power control in designing MAC layer protocols. SU-MAC developed by the same authors, efficiently uses the 'available' data and control bandwidth to send control information and results in increased throughput via decreasing contention on the control channel. However, SU-MAC protocol was limited for static ad-hoc network and also faced the busy-receiver node problem. We present the Extended SU-MAC (ESU-MAC) protocol which works mobile nodes. Also, we significantly improve the scheme of control information exchange in ESU-MAC to overcome the busy-receiver node problem and thus, further avoid the blockage of control channel for longer periods of time. A power control scheme is used as before to reduce interference and to effectively re-use the available bandwidth. Simulation results show that ESU-MAC protocol is promising for mobile, ad-hoc network in terms of reduced contention at the control channel and improved throughput because of channel re-use. Results show a considerable increase in throughput compared to SU-MAC which could be attributed to increased accessibility of control channel and improved utilization of data channels due to superior control information exchange scheme.

  14. Clinician Ratings of Interpreter Mediated Visits in Underserved Primary Care Settings with Ad hoc, In-person Professional, and Video Conferencing Modes

    PubMed Central

    Nápoles, Anna M.; Santoyo-Olsson, Jasmine; Karliner, Leah S.; O’Brien, Helen; Gregorich, Steven E.; Pérez-Stable, Eliseo J.

    2013-01-01

    Language interpretation ameliorates health disparities among underserved limited English-proficient patients, yet few studies have compared clinician satisfaction with these services. Self-administered clinician post-visit surveys compared the quality of interpretation and communication, visit satisfaction, degree of patient engagement, and cultural competence of visits using untrained people acting as interpreters (ad hoc), in-person professional, or video conferencing professional interpretation for 283 visits. Adjusting for clinician and patient characteristics, the quality of interpretation of in-person and video conferencing modes were rated similarly (OR=1.79; 95% CI 0.74, 4.33). The quality of in-person (OR=5.55; 95% CI 1.50, 20.51) and video conferencing (OR=3.10; 95% CI 1.16, 8.31) were rated higher than ad hoc interpretation. Self-assessed cultural competence was better for in-person versus video conferencing interpretation (OR=2.32; 95% CI 1.11, 4.86). Video conferencing interpretation increases access without compromising quality, but cultural nuances may be better addressed by in-person interpreters. Professional interpretation is superior to ad hoc (OR=4.15; 95% CI 1.43, 12.09). PMID:20173271

  15. An Energy Efficient Power Control Protocol for Ad Hoc Networks Using Directional Antennas

    NASA Astrophysics Data System (ADS)

    Quiroz-Perez, Carlos; Gulliver, T. Aaron

    A wireless ad hoc network is a collection of mobile nodes that can communicate with each other. Typically, nodes employ omnidirectional antennas. The use of directional antennas can increase spatial reuse, reduce the number of hops to a destination, reduce interference, and increase the transmission range in a specific direction. This is because omnidirectional antennas radiate equally in all directions, limiting the transmission range.

  16. Report of the Ad Hoc Committee on Religious and Cultural Celebrations in the Library.

    ERIC Educational Resources Information Center

    Rathemacher, Andree; Grubman, Sheila Black; Lahiri, Amar; Gilton, Donna; Sharif, Mohammed

    The charge of the University of Rhode Island's Ad Hoc Committee on Religious and Cultural Celebrations in the Library was to: investigate all opportunities for the library to educate the campus community about religious and cultural holidays; consider all the major religions of the world and the possibility of having displays for the symbols of…

  17. Integrated data lookup and replication scheme in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Chen, Kai; Nahrstedt, Klara

    2001-11-01

    Accessing remote data is a challenging task in mobile ad hoc networks. Two problems have to be solved: (1) how to learn about available data in the network; and (2) how to access desired data even when the original copy of the data is unreachable. In this paper, we develop an integrated data lookup and replication scheme to solve these problems. In our scheme, a group of mobile nodes collectively host a set of data to improve data accessibility for all members of the group. They exchange data availability information by broadcasting advertising (ad) messages to the group using an adaptive sending rate policy. The ad messages are used by other nodes to derive a local data lookup table, and to reduce data redundancy within a connected group. Our data replication scheme predicts group partitioning based on each node's current location and movement patterns, and replicates data to other partitions before partitioning occurs. Our simulations show that data availability information can quickly propagate throughout the network, and that the successful data access ratio of each node is significantly improved.

  18. ARSENAL: A Cross Layer Architecture for Secure Resilient Tactical Mobile AdHoc Networks

    DTIC Science & Technology

    2016-01-21

    stations separated by 0.5 to 1 km can be coherently measured to a single mobile subscriber using LTE signaling. These are the first measurements of...undertake three parallel but inter-coupled tasks geared towards a) performing measurements via real deployments and enhancing our understanding of layer...dependencies and vulnerabilities in mobile ad hoc networks; these measurements will be on existing testbeds at The views, opinions and/or findings

  19. ARSENAL: A Cross Layer Architecture for SecureResilient Tactical Mobile AdHoc Networks

    DTIC Science & Technology

    2016-01-21

    stations separated by 0.5 to 1 km can be coherently measured to a single mobile subscriber using LTE signaling. These are the first measurements of...undertake three parallel but inter-coupled tasks geared towards a) performing measurements via real deployments and enhancing our understanding of layer...dependencies and vulnerabilities in mobile ad hoc networks; these measurements will be on existing testbeds at The views, opinions and/or findings

  20. Panel Discussion : Report of the APS Ad-Hoc Committee on LGBT Issues

    NASA Astrophysics Data System (ADS)

    Atherton, Tim; Barthelemy, Ramon; Garmon, Savannah; Reeves, Kyle; APS Ad-Hoc Committee on LGBT Issues Team

    Following the presentation of the findings and recommendations of the APS Ad-Hoc Committee on LGBT Issues (C-LGBT) by Committee Chair Michael Falk, a panel discussion will be held featuring several members of the committee. The discussion will focus on how APS can best ensure the recommendations of the committee are carried out in a timely fashion and other ideas on future APS efforts toward LGBT inclusion in physics. Discussion topics will also include the research and other input that shaped the committee's findings and recommendations.

  1. Intelligent QoS routing algorithm based on improved AODV protocol for Ad Hoc networks

    NASA Astrophysics Data System (ADS)

    Huibin, Liu; Jun, Zhang

    2016-04-01

    Mobile Ad Hoc Networks were playing an increasingly important part in disaster reliefs, military battlefields and scientific explorations. However, networks routing difficulties are more and more outstanding due to inherent structures. This paper proposed an improved cuckoo searching-based Ad hoc On-Demand Distance Vector Routing protocol (CSAODV). It elaborately designs the calculation methods of optimal routing algorithm used by protocol and transmission mechanism of communication-package. In calculation of optimal routing algorithm by CS Algorithm, by increasing QoS constraint, the found optimal routing algorithm can conform to the requirements of specified bandwidth and time delay, and a certain balance can be obtained among computation spending, bandwidth and time delay. Take advantage of NS2 simulation software to take performance test on protocol in three circumstances and validate the feasibility and validity of CSAODV protocol. In results, CSAODV routing protocol is more adapt to the change of network topological structure than AODV protocol, which improves package delivery fraction of protocol effectively, reduce the transmission time delay of network, reduce the extra burden to network brought by controlling information, and improve the routing efficiency of network.

  2. Ad hoc supervision of general practice registrars as a 'community of practice': analysis, interpretation and re-presentation.

    PubMed

    Clement, T; Brown, J; Morrison, J; Nestel, D

    2016-05-01

    General practice registrars in Australia undertake most of their vocational training in accredited general practices. They typically see patients alone from the start of their community-based training and are expected to seek timely ad hoc support from their supervisor. Such ad hoc encounters are a mechanism for ensuring patient safety, but also provide an opportunity for learning and teaching. Wenger's (Communities of practice: learning, meaning, and identity. Cambridge University Press, New York, 1998) social theory of learning ('communities of practice') guided a secondary analysis of audio-recordings of ad hoc encounters. Data from one encounter is re-presented as an extended sequence to maintain congruence with the theoretical perspective and enhance vicariousness. An interpretive commentary communicates key features of Wenger's theory and highlights the researchers' interpretations. We argue that one encounter can reveal universal understandings of clinical supervision and that the process of naturalistic generalisation allows readers to transfer others' experiences to their own contexts. The paper raises significant analytic, interpretive, and representational issues. We highlight that report writing is an important, but infrequently discussed, part of research design. We discuss the challenges of supporting the learning and teaching that arises from adopting a socio-cultural lens and argue that such a perspective importantly captures the complex range of issues that work-based practitioners have to grapple with. This offers a challenge to how we research and seek to influence work-based learning and teaching in health care settings.

  3. Mapping Ad Hoc Communications Network of a Large Number Fixed-Wing UAV Swarm

    DTIC Science & Technology

    2017-03-01

    partitioned sub-swarms. The work covered in this thesis is to build a model of the NPS swarm’s communication network in ns-3 simulation software and use...partitioned sub- swarms. The work covered in this thesis is to build a model of the NPS swarm’s communication network in ns-3 simulation software and...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS MAPPING AD HOC COMMUNICATIONS NETWORK OF A LARGE NUMBER FIXED-WING UAV SWARM by Alexis

  4. Identifying strategy for ad hoc percutaneous coronary intervention in patients with anticipated unfavorable radial access: the Little Women study.

    PubMed

    Sgueglia, Gregory A; Todaro, Daniel; De Santis, Antonella; Conte, Micaela; Gioffrè, Gaetano; Di Giorgio, Angela; D'Errico, Fabrizio; Piccioni, Fabiana; Summaria, Francesco; Gaspardone, Achille

    2017-10-16

    Transradial percutaneous coronary intervention (PCI) offers important advantages over transfemoral PCI, including better outcomes. However, when there is indication to ad hoc PCI, a 6 French workflow is a common default strategy, hence potentially influencing vascular access selection in patients with anticipated small size radial artery. A multidimensional evaluation was performed to compare two ad hoc interventional strategies in women <160cm: a full 6 French workflow (namely 6 French introducer sheath, diagnostic catheters and guiding catheter) with a modified workflow consisting in the use of 5 French diagnostic catheters preceded by the placement of a 6 French sheath introducer and followed by a 6 French guiding catheter use for PCI. Overall 120 women (68±11years) were enrolled in the study. Coronary angiography has been performed using 5 French or 6 French diagnostic catheters in 57 (47.5%) and 63 (52.5%) cases, respectively. Radial spasm and switch to another access occurred more frequently among women who underwent coronary angiography with 6 French rather than 5 French diagnostic catheters (43% vs. 25%, p=0.03 and 2% vs. 11%, p=0.04, respectively). Total time to guidewire lesion crossing was also significantly higher when PCI has been preceded by 6 French rather than 5 French coronary angiography (23±11min vs 16±7min, p=0.013). In patients with anticipated unfavorable radial access, a workflow consisting in 6 French introducer sheath placement, 5 French coronary angiography, and 6 French coronary intervention is on multiple parameters the most straightforward and effective strategy. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. An epidemic model for biological data fusion in ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Chang, K. C.; Kotari, Vikas

    2009-05-01

    Bio terrorism can be a very refined and a catastrophic approach of attacking a nation. This requires the development of a complete architecture dedicatedly designed for this purpose which includes but is not limited to Sensing/Detection, Tracking and Fusion, Communication, and others. In this paper we focus on one such architecture and evaluate its performance. Various sensors for this specific purpose have been studied. The accent has been on use of Distributed systems such as ad-hoc networks and on application of epidemic data fusion algorithms to better manage the bio threat data. The emphasis has been on understanding the performance characteristics of these algorithms under diversified real time scenarios which are implemented through extensive JAVA based simulations. Through comparative studies on communication and fusion the performance of channel filter algorithm for the purpose of biological sensor data fusion are validated.

  6. Energy conservation in ad hoc multimedia networks using traffic-shaping mechanisms

    NASA Astrophysics Data System (ADS)

    Chandra, Surendar

    2003-12-01

    In this work, we explore network traffic shaping mechanisms that deliver packets at pre-determined intervals; allowing the network interface to transition to a lower power consuming sleep state. We focus our efforts on commodity devices, IEEE 802.11b ad hoc mode and popular streaming formats. We argue that factors such as the lack of scheduling clock phase synchronization among the participants and scheduling delays introduced by back ground tasks affect the potential energy savings. Increasing the periodic transmission delays to transmit data infrequently can offset some of these effects at the expense of flooding the wireless channel for longer periods of time; potentially increasing the time to acquire the channel for non-multimedia traffic. Buffering mechanisms built into media browsers can mitigate the effects of these added delays from being mis-interpreted as network congestion. We show that practical implementations of such traffic shaping mechanisms can offer significant energy savings.

  7. Adaptive Flow Control for Enabling Quality of Service in Tactical Ad Hoc Wireless Networks

    DTIC Science & Technology

    2010-12-01

    environment in wireless networks , we use sensors in the network routers to detect and respond to congestion. We use backpressure techniques... wireless mesh network . In the current approach, we used OLSR as the routing scheme. However, B.A.T.M.A.N. offers the significant advantage of being based...Control and QoS Routing in Multi-Channel Wireless Mesh Networks ,” 68-77. ACM International Symposium on Mobile Ad Hoc Networking &

  8. A Feasible Approach for an Early Manned Lunar Landing. Part II: Detailed Report of Ad Hoc Task Group

    NASA Technical Reports Server (NTRS)

    Fleming, William A.

    1961-01-01

    This report, in two parts, presents a program development plan for attempting a first manned lunar landing in 1967. The two parts consist of a Summary Report and a Detailed Report representing the coordinated output of the Ad Hoc Task Group assigned to the study. The study was started in response to the request for such a study by the Associate Administrator in his memorandum of May 2, 1961 establishing the Ad Hoc Task Group. The purpose of the study was to take a first cut at the tasks associated with the design, development and construction of the equipment and facilities as well as the development of the crews, and to show the time phasing 6f these tasks. Included are the space sciences, life science and advanced technology tasks whose data and results are needed for designing and developing the systems required in carrying out the mission. The plan presented in the two reports does not presume to be a firm plan. Its basic purpose is, by choosing one feasible method, to size up the scope, schedule and cost of the job, discover the main problems, pacing items and major decisions and provide a threshold from which a firm and detailed project development plan can be jointly formulated by the various elements of NASA.

  9. Scalable Authenticated Tree Based Group Key Exchange for Ad-Hoc Groups

    NASA Astrophysics Data System (ADS)

    Desmedt, Yvo; Lange, Tanja; Burmester, Mike

    Task-specific groups are often formed in an ad-hoc manner within large corporate structures, such as companies. Take the following typical scenario: A director decides to set up a task force group for some specific project. An order is passed down the hierarchy where it finally reaches a manager who selects some employees to form the group. The members should communicate in a secure way and for efficiency, a symmetric encryption system is chosen. To establish a joint secret key for the group, a group key exchange (GKE) protocol is used. We show how to use an existing Public Key Infrastructure (PKI) to achieve authenticated GKE by modifying the protocol and particularly by including signatures.

  10. Ad Hoc modeling, expert problem solving, and R&T program evaluation

    NASA Technical Reports Server (NTRS)

    Silverman, B. G.; Liebowitz, J.; Moustakis, V. S.

    1983-01-01

    A simplified cost and time (SCAT) analysis program utilizing personal-computer technology is presented and demonstrated in the case of the NASA-Goddard end-to-end data system. The difficulties encountered in implementing complex program-selection and evaluation models in the research and technology field are outlined. The prototype SCAT system described here is designed to allow user-friendly ad hoc modeling in real time and at low cost. A worksheet constructed on the computer screen displays the critical parameters and shows how each is affected when one is altered experimentally. In the NASA case, satellite data-output and control requirements, ground-facility data-handling capabilities, and project priorities are intricately interrelated. Scenario studies of the effects of spacecraft phaseout or new spacecraft on throughput and delay parameters are shown. The use of a network of personal computers for higher-level coordination of decision-making processes is suggested, as a complement or alternative to complex large-scale modeling.

  11. AD Hoc Study on Human Robot Interface Issues

    DTIC Science & Technology

    2002-09-01

    of joint range of motion limits on strength. When the angle of a fully deflected aircraft rudder/ brake pedal is beyond the limit of ankle...mobility, the pedal will seem to have excessive resistance. In addition, this will prevent the pilot from fully utilizing the brakes of the aircraft...importance and value added of HE efforts. 34 Center High-Mounted Brake Lights. In 1985, after extensive HE studies showing positive

  12. Enhancement of Beaconless Location-Based Routing with Signal Strength Assistance for Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Chen, Guowei; Itoh, Kenichi; Sato, Takuro

    Routing in Ad-hoc networks is unreliable due to the mobility of the nodes. Location-based routing protocols, unlike other protocols which rely on flooding, excel in network scalability. Furthermore, new location-based routing protocols, like, e. g. BLR [1], IGF [2], & CBF [3] have been proposed, with the feature of not requiring beacons in MAC-layer, which improve more in terms of scalability. Such beaconless routing protocols can work efficiently in dense network areas. However, these protocols' algorithms have no ability to avoid from routing into sparse areas. In this article, historical signal strength has been added as a factor into the BLR algorithm, which avoids routing into sparse area, and consequently improves the global routing efficiency.

  13. Robotic disaster recovery efforts with ad-hoc deployable cloud computing

    NASA Astrophysics Data System (ADS)

    Straub, Jeremy; Marsh, Ronald; Mohammad, Atif F.

    2013-06-01

    Autonomous operations of search and rescue (SaR) robots is an ill posed problem, which is complexified by the dynamic disaster recovery environment. In a typical SaR response scenario, responder robots will require different levels of processing capabilities during various parts of the response effort and will need to utilize multiple algorithms. Placing these capabilities onboard the robot is a mediocre solution that precludes algorithm specific performance optimization and results in mediocre performance. Architecture for an ad-hoc, deployable cloud environment suitable for use in a disaster response scenario is presented. Under this model, each service provider is optimized for the task and maintains a database of situation-relevant information. This service-oriented architecture (SOA 3.0) compliant framework also serves as an example of the efficient use of SOA 3.0 in an actual cloud application.

  14. Trust Management in Mobile Ad Hoc Networks for Bias Minimization and Application Performance Maximization

    DTIC Science & Technology

    2014-02-26

    set of anomaly detection rules 62 I.-R. Chen et al. / Ad Hoc Networks 19 (2014) 59–74 Author’s personal copy including the interval rule (for...deficiencies in anomaly detection (e.g., imperfection of rules) by a false negative probability (PHfn) of misidentifying an unhealthy node as a...multimedia servers, Multimedia Syst. 8 (2) (2000) 83–91. [53] R. Mitchell, I.R. Chen, Adaptive intrusion detection for unmanned aircraft systems based on

  15. An adaptive density-based routing protocol for flying Ad Hoc networks

    NASA Astrophysics Data System (ADS)

    Zheng, Xueli; Qi, Qian; Wang, Qingwen; Li, Yongqiang

    2017-10-01

    An Adaptive Density-based Routing Protocol (ADRP) for Flying Ad Hoc Networks (FANETs) is proposed in this paper. The main objective is to calculate forwarding probability adaptively in order to increase the efficiency of forwarding in FANETs. ADRP dynamically fine-tunes the rebroadcasting probability of a node for routing request packets according to the number of neighbour nodes. Indeed, it is more interesting to privilege the retransmission by nodes with little neighbour nodes. We describe the protocol, implement it and evaluate its performance using NS-2 network simulator. Simulation results reveal that ADRP achieves better performance in terms of the packet delivery fraction, average end-to-end delay, normalized routing load, normalized MAC load and throughput, which is respectively compared with AODV.

  16. A Family of ACO Routing Protocols for Mobile Ad Hoc Networks

    PubMed Central

    Rupérez Cañas, Delfín; Sandoval Orozco, Ana Lucila; García Villalba, Luis Javier; Kim, Tai-hoon

    2017-01-01

    In this work, an ACO routing protocol for mobile ad hoc networks based on AntHocNet is specified. As its predecessor, this new protocol, called AntOR, is hybrid in the sense that it contains elements from both reactive and proactive routing. Specifically, it combines a reactive route setup process with a proactive route maintenance and improvement process. Key aspects of the AntOR protocol are the disjoint-link and disjoint-node routes, separation between the regular pheromone and the virtual pheromone in the diffusion process and the exploration of routes, taking into consideration the number of hops in the best routes. In this work, a family of ACO routing protocols based on AntOR is also specified. These protocols are based on protocol successive refinements. In this work, we also present a parallelized version of AntOR that we call PAntOR. Using programming multiprocessor architectures based on the shared memory protocol, PAntOR allows running tasks in parallel using threads. This parallelization is applicable in the route setup phase, route local repair process and link failure notification. In addition, a variant of PAntOR that consists of having more than one interface, which we call PAntOR-MI (PAntOR-Multiple Interface), is specified. This approach parallelizes the sending of broadcast messages by interface through threads. PMID:28531159

  17. A Family of ACO Routing Protocols for Mobile Ad Hoc Networks.

    PubMed

    Rupérez Cañas, Delfín; Sandoval Orozco, Ana Lucila; García Villalba, Luis Javier; Kim, Tai-Hoon

    2017-05-22

    In this work, an ACO routing protocol for mobile ad hoc networks based on AntHocNet is specified. As its predecessor, this new protocol, called AntOR, is hybrid in the sense that it contains elements from both reactive and proactive routing. Specifically, it combines a reactive route setup process with a proactive route maintenance and improvement process. Key aspects of the AntOR protocol are the disjoint-link and disjoint-node routes, separation between the regular pheromone and the virtual pheromone in the diffusion process and the exploration of routes, taking into consideration the number of hops in the best routes. In this work, a family of ACO routing protocols based on AntOR is also specified. These protocols are based on protocol successive refinements. In this work, we also present a parallelized version of AntOR that we call PAntOR. Using programming multiprocessor architectures based on the shared memory protocol, PAntOR allows running tasks in parallel using threads. This parallelization is applicable in the route setup phase, route local repair process and link failure notification. In addition, a variant of PAntOR that consists of having more than one interface, which we call PAntOR-MI (PAntOR-Multiple Interface), is specified. This approach parallelizes the sending of broadcast messages by interface through threads.

  18. Cross-layer protocols optimized for real-time multimedia services in energy-constrained mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2003-07-01

    Mobile ad hoc networking (MANET) supports self-organizing, mobile infrastructures and enables an autonomous network of mobile nodes that can operate without a wired backbone. Ad hoc networks are characterized by multihop, wireless connectivity via packet radios and by the need for efficient dynamic protocols. All routers are mobile and can establish connectivity with other nodes only when they are within transmission range. Importantly, ad hoc wireless nodes are resource-constrained, having limited processing, memory, and battery capacity. Delivery of high quality-ofservice (QoS), real-time multimedia services from Internet-based applications over a MANET is a challenge not yet achieved by proposed Internet Engineering Task Force (IETF) ad hoc network protocols in terms of standard performance metrics such as end-to-end throughput, packet error rate, and delay. In the distributed operations of route discovery and maintenance, strong interaction occurs across MANET protocol layers, in particular, the physical, media access control (MAC), network, and application layers. The QoS requirements are specified for the service classes by the application layer. The cross-layer design must also satisfy the battery-limited energy constraints, by minimizing the distributed power consumption at the nodes and of selected routes. Interactions across the layers are modeled in terms of the set of concatenated design parameters including associated energy costs. Functional dependencies of the QoS metrics are described in terms of the concatenated control parameters. New cross-layer designs are sought that optimize layer interdependencies to achieve the "best" QoS available in an energy-constrained, time-varying network. The protocol design, based on a reactive MANET protocol, adapts the provisioned QoS to dynamic network conditions and residual energy capacities. The cross-layer optimization is based on stochastic dynamic programming conditions derived from time-dependent models of

  19. Linking Satellites Via Earth "Hot Spots" and the Internet to Form Ad Hoc Constellations

    NASA Technical Reports Server (NTRS)

    Mandl, Dan; Frye, Stu; Grosvenor, Sandra; Ingram, Mary Ann; Langley, John; Miranda, Felix; Lee, Richard Q.; Romanofsky, Robert; Zaman, Afoz; Popovic, Zoya

    2004-01-01

    As more assets are placed in orbit, opportunities emerge to combine various sets of satellites in temporary constellations to perform collaborative image collections. Often, new operations concepts for a satellite or set of satellites emerge after launch. To the degree with which new space assets can be inexpensively and rapidly integrated into temporary or "ad hoc" constellations, will determine whether these new ideas will be implemented or not. On the Earth Observing 1 (EO-1) satellite, a New Millennium Program mission, a number of experiments were conducted and are being conducted to demonstrate various aspects of an architecture that, when taken as a whole, will enable progressive mission autonomy. In particular, the target architecture will use adaptive ground antenna arrays to form, as close as possible, the equivalent of wireless access points for low earth orbiting satellites. Coupled with various ground and flight software and the Internet. the architecture enables progressive mission autonomy. Thus, new collaborative sensing techniques can be implemented post-launch. This paper will outline the overall operations concept and highlight details of both the research effort being conducted in ad hoc constellations, mission autonomy and

  20. Energy-Aware Multipath Routing Scheme Based on Particle Swarm Optimization in Mobile Ad Hoc Networks

    PubMed Central

    Robinson, Y. Harold; Rajaram, M.

    2015-01-01

    Mobile ad hoc network (MANET) is a collection of autonomous mobile nodes forming an ad hoc network without fixed infrastructure. Dynamic topology property of MANET may degrade the performance of the network. However, multipath selection is a great challenging task to improve the network lifetime. We proposed an energy-aware multipath routing scheme based on particle swarm optimization (EMPSO) that uses continuous time recurrent neural network (CTRNN) to solve optimization problems. CTRNN finds the optimal loop-free paths to solve link disjoint paths in a MANET. The CTRNN is used as an optimum path selection technique that produces a set of optimal paths between source and destination. In CTRNN, particle swarm optimization (PSO) method is primly used for training the RNN. The proposed scheme uses the reliability measures such as transmission cost, energy factor, and the optimal traffic ratio between source and destination to increase routing performance. In this scheme, optimal loop-free paths can be found using PSO to seek better link quality nodes in route discovery phase. PSO optimizes a problem by iteratively trying to get a better solution with regard to a measure of quality. The proposed scheme discovers multiple loop-free paths by using PSO technique. PMID:26819966

  1. Modern foreign language teachers - don't leave those kids alone! Linguistic-cultural "give and take" in an ad-hoc tutoring scheme

    NASA Astrophysics Data System (ADS)

    Leroy, Norah

    2017-08-01

    This paper addresses the theme of social inclusion through language learning. The focus is on an ad-hoc tutoring scheme set up between newly arrived British migrant pupils and French monolingual pupils in a small secondary school in the south-west of France. Though the original objective of this tutoring scheme was to improve the English skills of the younger pupils, feedback reports indicated that it also had a positive impact on the relationship between the British migrant pupils and their French peers. Teachers believed that those involved participated more fully in class, and appeared more self-assured and generally happy thanks to the interpersonal relationships this scheme helped to forge. This study demonstrates the necessity of analysing the socio-cultural context migrants may find themselves in, in order to identify potential challenges. The ad-hoc tutoring scheme described here is an example of how language learning can support the integration and inclusion of "new generation" migrants into everyday school life.

  2. Quality of service routing in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Sane, Sachin J.; Patcha, Animesh; Mishra, Amitabh

    2003-08-01

    An efficient routing protocol is essential to guarantee application level quality of service running on wireless ad hoc networks. In this paper we propose a novel routing algorithm that computes a path between a source and a destination by considering several important constraints such as path-life, availability of sufficient energy as well as buffer space in each of the nodes on the path between the source and destination. The algorithm chooses the best path from among the multiples paths that it computes between two endpoints. We consider the use of control packets that run at a priority higher than the data packets in determining the multiple paths. The paper also examines the impact of different schedulers such as weighted fair queuing, and weighted random early detection among others in preserving the QoS level guarantees. Our extensive simulation results indicate that the algorithm improves the overall lifetime of a network, reduces the number of dropped packets, and decreases the end-to-end delay for real-time voice application.

  3. Noise-Assisted Concurrent Multipath Traffic Distribution in Ad Hoc Networks

    PubMed Central

    Murata, Masayuki

    2013-01-01

    The concept of biologically inspired networking has been introduced to tackle unpredictable and unstable situations in computer networks, especially in wireless ad hoc networks where network conditions are continuously changing, resulting in the need of robustness and adaptability of control methods. Unfortunately, existing methods often rely heavily on the detailed knowledge of each network component and the preconfigured, that is, fine-tuned, parameters. In this paper, we utilize a new concept, called attractor perturbation (AP), which enables controlling the network performance using only end-to-end information. Based on AP, we propose a concurrent multipath traffic distribution method, which aims at lowering the average end-to-end delay by only adjusting the transmission rate on each path. We demonstrate through simulations that, by utilizing the attractor perturbation relationship, the proposed method achieves a lower average end-to-end delay compared to other methods which do not take fluctuations into account. PMID:24319375

  4. A memetic optimization algorithm for multi-constrained multicast routing in ad hoc networks

    PubMed Central

    Hammad, Karim; El Bakly, Ahmed M.

    2018-01-01

    A mobile ad hoc network is a conventional self-configuring network where the routing optimization problem—subject to various Quality-of-Service (QoS) constraints—represents a major challenge. Unlike previously proposed solutions, in this paper, we propose a memetic algorithm (MA) employing an adaptive mutation parameter, to solve the multicast routing problem with higher search ability and computational efficiency. The proposed algorithm utilizes an updated scheme, based on statistical analysis, to estimate the best values for all MA parameters and enhance MA performance. The numerical results show that the proposed MA improved the delay and jitter of the network, while reducing computational complexity as compared to existing algorithms. PMID:29509760

  5. A memetic optimization algorithm for multi-constrained multicast routing in ad hoc networks.

    PubMed

    Ramadan, Rahab M; Gasser, Safa M; El-Mahallawy, Mohamed S; Hammad, Karim; El Bakly, Ahmed M

    2018-01-01

    A mobile ad hoc network is a conventional self-configuring network where the routing optimization problem-subject to various Quality-of-Service (QoS) constraints-represents a major challenge. Unlike previously proposed solutions, in this paper, we propose a memetic algorithm (MA) employing an adaptive mutation parameter, to solve the multicast routing problem with higher search ability and computational efficiency. The proposed algorithm utilizes an updated scheme, based on statistical analysis, to estimate the best values for all MA parameters and enhance MA performance. The numerical results show that the proposed MA improved the delay and jitter of the network, while reducing computational complexity as compared to existing algorithms.

  6. BCDP: Budget Constrained and Delay-Bounded Placement for Hybrid Roadside Units in Vehicular Ad Hoc Networks

    PubMed Central

    Li, Peng; Huang, Chuanhe; Liu, Qin

    2014-01-01

    In vehicular ad hoc networks, roadside units (RSUs) placement has been proposed to improve the the overall network performance in many ITS applications. This paper addresses the budget constrained and delay-bounded placement problem (BCDP) for roadside units in vehicular ad hoc networks. There are two types of RSUs: cable connected RSU (c-RSU) and wireless RSU (w-RSU). c-RSUs are interconnected through wired lines, and they form the backbone of VANETs, while w-RSUs connect to other RSUs through wireless communication and serve as an economical extension of the coverage of c-RSUs. The delay-bounded coverage range and deployment cost of these two cases are totally different. We are given a budget constraint and a delay bound, the problem is how to find the optimal candidate sites with the maximal delay-bounded coverage to place RSUs such that a message from any c-RSU in the region can be disseminated to the more vehicles within the given budget constraint and delay bound. We first prove that the BCDP problem is NP-hard. Then we propose several algorithms to solve the BCDP problem. Simulation results show the heuristic algorithms can significantly improve the coverage range and reduce the total deployment cost, compared with other heuristic methods. PMID:25436656

  7. Impact of Beamforming on the Path Connectivity in Cognitive Radio Ad Hoc Networks

    PubMed Central

    Dung, Le The; Hieu, Tran Dinh; Choi, Seong-Gon; Kim, Byung-Seo; An, Beongku

    2017-01-01

    This paper investigates the impact of using directional antennas and beamforming schemes on the connectivity of cognitive radio ad hoc networks (CRAHNs). Specifically, considering that secondary users use two kinds of directional antennas, i.e., uniform linear array (ULA) and uniform circular array (UCA) antennas, and two different beamforming schemes, i.e., randomized beamforming and center-directed to communicate with each other, we study the connectivity of all combination pairs of directional antennas and beamforming schemes and compare their performances to those of omnidirectional antennas. The results obtained in this paper show that, compared with omnidirectional transmission, beamforming transmission only benefits the connectivity when the density of secondary user is moderate. Moreover, the combination of UCA and randomized beamforming scheme gives the highest path connectivity in all evaluating scenarios. Finally, the number of antenna elements and degree of path loss greatly affect path connectivity in CRAHNs. PMID:28346377

  8. Context dependent off loading for cloudlet in mobile ad-hoc network

    NASA Astrophysics Data System (ADS)

    Bhatt, N.; Nadesh, R. K.; ArivuSelvan, K.

    2017-11-01

    Cloud Computing in Mobile Ad-hoc network is emerging part of research consideration as the demand and competency of mobile devices increased in last few years. To follow out operation within the remote cloud builds the postponement and influences the administration standard. To keep away from this trouble cloudlet is presented. Cloudlet gives identical support of the devices as cloud at low inactivity however at high transfer speed. Be that as it may, choice of a cloudlet for offloading calculation with flat energy is a noteworthy test if multiple cloud let is accessible adjacent. Here I proposed energy and bandwidth (Traffic overload for communication with cloud) aware cloudlet selection strategy based on the context dependency of the device location. It works on the basis of mobile device location and bandwidth availability of cloudlet. The cloudlet offloading and selection process using given solution is simulated in Cloud ~ Simulator.

  9. An enhanced performance through agent-based secure approach for mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Bisen, Dhananjay; Sharma, Sanjeev

    2018-01-01

    This paper proposes an agent-based secure enhanced performance approach (AB-SEP) for mobile ad hoc network. In this approach, agent nodes are selected through optimal node reliability as a factor. This factor is calculated on the basis of node performance features such as degree difference, normalised distance value, energy level, mobility and optimal hello interval of node. After selection of agent nodes, a procedure of malicious behaviour detection is performed using fuzzy-based secure architecture (FBSA). To evaluate the performance of the proposed approach, comparative analysis is done with conventional schemes using performance parameters such as packet delivery ratio, throughput, total packet forwarding, network overhead, end-to-end delay and percentage of malicious detection.

  10. Energy Aware Cluster-Based Routing in Flying Ad-Hoc Networks.

    PubMed

    Aadil, Farhan; Raza, Ali; Khan, Muhammad Fahad; Maqsood, Muazzam; Mehmood, Irfan; Rho, Seungmin

    2018-05-03

    Flying ad-hoc networks (FANETs) are a very vibrant research area nowadays. They have many military and civil applications. Limited battery energy and the high mobility of micro unmanned aerial vehicles (UAVs) represent their two main problems, i.e., short flight time and inefficient routing. In this paper, we try to address both of these problems by means of efficient clustering. First, we adjust the transmission power of the UAVs by anticipating their operational requirements. Optimal transmission range will have minimum packet loss ratio (PLR) and better link quality, which ultimately save the energy consumed during communication. Second, we use a variant of the K-Means Density clustering algorithm for selection of cluster heads. Optimal cluster heads enhance the cluster lifetime and reduce the routing overhead. The proposed model outperforms the state of the art artificial intelligence techniques such as Ant Colony Optimization-based clustering algorithm and Grey Wolf Optimization-based clustering algorithm. The performance of the proposed algorithm is evaluated in term of number of clusters, cluster building time, cluster lifetime and energy consumption.

  11. A high performance, ad-hoc, fuzzy query processing system for relational databases

    NASA Technical Reports Server (NTRS)

    Mansfield, William H., Jr.; Fleischman, Robert M.

    1992-01-01

    Database queries involving imprecise or fuzzy predicates are currently an evolving area of academic and industrial research. Such queries place severe stress on the indexing and I/O subsystems of conventional database environments since they involve the search of large numbers of records. The Datacycle architecture and research prototype is a database environment that uses filtering technology to perform an efficient, exhaustive search of an entire database. It has recently been modified to include fuzzy predicates in its query processing. The approach obviates the need for complex index structures, provides unlimited query throughput, permits the use of ad-hoc fuzzy membership functions, and provides a deterministic response time largely independent of query complexity and load. This paper describes the Datacycle prototype implementation of fuzzy queries and some recent performance results.

  12. Federal Government Printing and Publishing: Policy Issues. Report of the Ad Hoc Advisory Committee on Revision of Title 44.

    ERIC Educational Resources Information Center

    Joint Committee on Printing, Washington, DC.

    Designed to present a better understanding of the government's system of printing and distributing information and to highlight problems, alternatives, and important policy questions, this report synthesizes 13 weeks of the Ad Hoc Advisory Committee hearings on six topics: (1) Administration of policy--who should establish and administer policy in…

  13. Distributive routing and congestion control in wireless multihop ad hoc communication networks

    NASA Astrophysics Data System (ADS)

    Glauche, Ingmar; Krause, Wolfram; Sollacher, Rudolf; Greiner, Martin

    2004-10-01

    Due to their inherent complexity, engineered wireless multihop ad hoc communication networks represent a technological challenge. Having no mastering infrastructure the nodes have to selforganize themselves in such a way that for example network connectivity, good data traffic performance and robustness are guaranteed. In this contribution the focus is on routing and congestion control. First, random data traffic along shortest path routes is studied by simulations as well as theoretical modeling. Measures of congestion like end-to-end time delay and relaxation times are given. A scaling law of the average time delay with respect to network size is revealed and found to depend on the underlying network topology. In the second step, a distributive routing and congestion control is proposed. Each node locally propagates its routing cost estimates and information about its congestion state to its neighbors, which then update their respective cost estimates. This allows for a flexible adaptation of end-to-end routes to the overall congestion state of the network. Compared to shortest-path routing, the critical network load is significantly increased.

  14. Sketching Awareness: A Participatory Study to Elicit Designs for Supporting Ad Hoc Emergency Medical Teamwork

    PubMed Central

    Kusunoki, Diana; Sarcevic, Aleksandra; Zhang, Zhan; Yala, Maria

    2014-01-01

    Prior CSCW research on awareness in clinical settings has mostly focused on higher-level team coordination spanning across longer-term trajectories at the department and inter-department levels. In this paper, we offer a perspective on what awareness means within the context of an ad hoc, time- and safety-critical medical setting by looking at teams treating severely ill patients with urgent needs. We report findings from four participatory design workshops conducted with emergency medicine clinicians at two regional emergency departments. Workshops were developed to elicit design ideas for information displays that support awareness in emergency medical situations. Through analysis of discussions and clinicians’ sketches of information displays, we identified five features of teamwork that can be used as a foundation for supporting awareness from the perspective of clinicians. Based on these findings, we contribute rich descriptions of four facets of awareness that teams manage during emergency medical situations: team member awareness, elapsed time awareness, teamwork-oriented and patient-driven task awareness, and overall progress awareness. We then discuss these four awareness types in relation to awareness facets found in the CSCW literature. PMID:25870498

  15. Assessment of interbreeding and introgression of farm genes into a small Scottish Atlantic salmon Salmo salar stock: ad hoc samples - ad hoc results?

    PubMed

    Verspoor, E; Knox, D; Marshall, S

    2016-12-01

    An eclectic set of tissues and existing data, including purposely collected samples, spanning 1997-2006, was used in an ad hoc assessment of hybridization and introgression of farmed wild Atlantic salmon Salmo salar in the small Loch na Thull (LnT) catchment in north-west Scotland. The catchment is in an area of marine farm production and contains freshwater smolt rearing cages. The LnT S. salar stock was found to be genetically distinctive from stocks in neighbouring rivers and, despite regular reports of feral farm S. salar, there was no evidence of physical or genetic mixing. This cannot be completely ruled out, however, and low level mixing with other local wild stocks has been suggested. The LnT population appeared underpinned by relatively smaller effective number of breeders (N eb ) and showed relatively low levels of genetic diversity, consistent with a small effective population size. Small sample sizes, an incomplete farm baseline and the use of non-diagnostic molecular markers, constrain the power of the analysis but the findings strongly support the LnT catchment having a genetically distinct wild S. salar population little affected by interbreeding with feral farm escapes. © 2016 The Fisheries Society of the British Isles.

  16. Introduction to Blueweb: A Decentralized Scatternet Formation Algorithm for Bluetooth Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Yu, Chih-Min; Huang, Chia-Chi

    In this letter, a decentralized scatternet formation algorithm called Bluelayer is proposed. First, Bluelayer uses a designated root to construct a tree-shaped subnet and propagates an integer variable k1 called counter limit as well as a constant k in its downstream direction to determine new roots. Then each new root asks its upstream master to start a return connection procedure to convert the tree-shaped subnet into a web-shaped subnet for its immediate upstream root. At the same time, each new root repeats the same procedure as the root to build its own subnet until the whole scatternet is formed. Simulation results show that Bluelayer achieves good network scalability and generates an efficient scatternet configuration for various sizes of Bluetooth ad hoc network.

  17. Predicting impact of multi-paths on phase change in map-based vehicular ad hoc networks

    NASA Astrophysics Data System (ADS)

    Rahmes, Mark; Lemieux, George; Sonnenberg, Jerome; Chester, David B.

    2014-05-01

    Dynamic Spectrum Access, which through its ability to adapt the operating frequency of a radio, is widely believed to be a solution to the limited spectrum problem. Mobile Ad Hoc Networks (MANETs) can extend high capacity mobile communications over large areas where fixed and tethered-mobile systems are not available. In one use case with high potential impact cognitive radio employs spectrum sensing to facilitate identification of allocated frequencies not currently accessed by their primary users. Primary users own the rights to radiate at a specific frequency and geographic location, secondary users opportunistically attempt to radiate at a specific frequency when the primary user is not using it. We quantify optimal signal detection in map based cognitive radio networks with multiple rapidly varying phase changes and multiple orthogonal signals. Doppler shift occurs due to reflection, scattering, and rapid vehicle movement. Path propagation as well as vehicle movement produces either constructive or destructive interference with the incident wave. Our signal detection algorithms can assist the Doppler spread compensation algorithm by deciding how many phase changes in signals are present in a selected band of interest. Additionally we can populate a spatial radio environment map (REM) database with known information that can be leveraged in an ad hoc network to facilitate Dynamic Spectrum Access. We show how topography can help predict the impact of multi-paths on phase change, as well as about the prediction from dense traffic areas. Utilization of high resolution geospatial data layers in RF propagation analysis is directly applicable.

  18. Post Hoc Analyses of ApoE Genotype-Defined Subgroups in Clinical Trials.

    PubMed

    Kennedy, Richard E; Cutter, Gary R; Wang, Guoqiao; Schneider, Lon S

    2016-01-01

    Many post hoc analyses of clinical trials in Alzheimer's disease (AD) and mild cognitive impairment (MCI) are in small Phase 2 trials. Subject heterogeneity may lead to statistically significant post hoc results that cannot be replicated in larger follow-up studies. We investigated the extent of this problem using simulation studies mimicking current trial methods with post hoc analyses based on ApoE4 carrier status. We used a meta-database of 24 studies, including 3,574 subjects with mild AD and 1,171 subjects with MCI/prodromal AD, to simulate clinical trial scenarios. Post hoc analyses examined if rates of progression on the Alzheimer's Disease Assessment Scale-cognitive (ADAS-cog) differed between ApoE4 carriers and non-carriers. Across studies, ApoE4 carriers were younger and had lower baseline scores, greater rates of progression, and greater variability on the ADAS-cog. Up to 18% of post hoc analyses for 18-month trials in AD showed greater rates of progression for ApoE4 non-carriers that were statistically significant but unlikely to be confirmed in follow-up studies. The frequency of erroneous conclusions dropped below 3% with trials of 100 subjects per arm. In MCI, rates of statistically significant differences with greater progression in ApoE4 non-carriers remained below 3% unless sample sizes were below 25 subjects per arm. Statistically significant differences for ApoE4 in post hoc analyses often reflect heterogeneity among small samples rather than true differential effect among ApoE4 subtypes. Such analyses must be viewed cautiously. ApoE genotype should be incorporated into the design stage to minimize erroneous conclusions.

  19. Cooperative Education and the Academy. and Response to the Preliminary Report of the Ad Hoc Committee on Cooperative Education and the Curriculum.

    ERIC Educational Resources Information Center

    Heinemann, Harry N.; And Others

    1988-01-01

    Two articles describe the final report submitted by the Ad Hoc Committee on Cooperative Education and the Curriculum to the Cooperative Education Association and the reaction to that report by the person who established the committee. (JOW)

  20. History-based route selection for reactive ad hoc routing protocols

    NASA Astrophysics Data System (ADS)

    Medidi, Sirisha; Cappetto, Peter

    2007-04-01

    Ad hoc networks rely on cooperation in order to operate, but in a resource constrained environment not all nodes behave altruistically. Selfish nodes preserve their own resources and do not forward packets not in their own self interest. These nodes degrade the performance of the network, but judicious route selection can help maintain performance despite this behavior. Many route selection algorithms place importance on shortness of the route rather than its reliability. We introduce a light-weight route selection algorithm that uses past behavior to judge the quality of a route rather than solely on the length of the route. It draws information from the underlying routing layer at no extra cost and selects routes with a simple algorithm. This technique maintains this data in a small table, which does not place a high cost on memory. History-based route selection's minimalism suits the needs the portable wireless devices and is easy to implement. We implemented our algorithm and tested it in the ns2 environment. Our simulation results show that history-based route selection achieves higher packet delivery and improved stability than its length-based counterpart.

  1. Random Time Identity Based Firewall In Mobile Ad hoc Networks

    NASA Astrophysics Data System (ADS)

    Suman, Patel, R. B.; Singh, Parvinder

    2010-11-01

    A mobile ad hoc network (MANET) is a self-organizing network of mobile routers and associated hosts connected by wireless links. MANETs are highly flexible and adaptable but at the same time are highly prone to security risks due to the open medium, dynamically changing network topology, cooperative algorithms, and lack of centralized control. Firewall is an effective means of protecting a local network from network-based security threats and forms a key component in MANET security architecture. This paper presents a review of firewall implementation techniques in MANETs and their relative merits and demerits. A new approach is proposed to select MANET nodes at random for firewall implementation. This approach randomly select a new node as firewall after fixed time and based on critical value of certain parameters like power backup. This approach effectively balances power and resource utilization of entire MANET because responsibility of implementing firewall is equally shared among all the nodes. At the same time it ensures improved security for MANETs from outside attacks as intruder will not be able to find out the entry point in MANET due to the random selection of nodes for firewall implementation.

  2. Virtual machine-based simulation platform for mobile ad-hoc network-based cyber infrastructure

    DOE PAGES

    Yoginath, Srikanth B.; Perumalla, Kayla S.; Henz, Brian J.

    2015-09-29

    In modeling and simulating complex systems such as mobile ad-hoc networks (MANETs) in de-fense communications, it is a major challenge to reconcile multiple important considerations: the rapidity of unavoidable changes to the software (network layers and applications), the difficulty of modeling the critical, implementation-dependent behavioral effects, the need to sustain larger scale scenarios, and the desire for faster simulations. Here we present our approach in success-fully reconciling them using a virtual time-synchronized virtual machine(VM)-based parallel ex-ecution framework that accurately lifts both the devices as well as the network communications to a virtual time plane while retaining full fidelity. At themore » core of our framework is a scheduling engine that operates at the level of a hypervisor scheduler, offering a unique ability to execute multi-core guest nodes over multi-core host nodes in an accurate, virtual time-synchronized manner. In contrast to other related approaches that suffer from either speed or accuracy issues, our framework provides MANET node-wise scalability, high fidelity of software behaviors, and time-ordering accuracy. The design and development of this framework is presented, and an ac-tual implementation based on the widely used Xen hypervisor system is described. Benchmarks with synthetic and actual applications are used to identify the benefits of our approach. The time inaccuracy of traditional emulation methods is demonstrated, in comparison with the accurate execution of our framework verified by theoretically correct results expected from analytical models of the same scenarios. In the largest high fidelity tests, we are able to perform virtual time-synchronized simulation of 64-node VM-based full-stack, actual software behaviors of MANETs containing a mix of static and mobile (unmanned airborne vehicle) nodes, hosted on a 32-core host, with full fidelity of unmodified ad-hoc routing protocols, unmodified

  3. Virtual machine-based simulation platform for mobile ad-hoc network-based cyber infrastructure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yoginath, Srikanth B.; Perumalla, Kayla S.; Henz, Brian J.

    In modeling and simulating complex systems such as mobile ad-hoc networks (MANETs) in de-fense communications, it is a major challenge to reconcile multiple important considerations: the rapidity of unavoidable changes to the software (network layers and applications), the difficulty of modeling the critical, implementation-dependent behavioral effects, the need to sustain larger scale scenarios, and the desire for faster simulations. Here we present our approach in success-fully reconciling them using a virtual time-synchronized virtual machine(VM)-based parallel ex-ecution framework that accurately lifts both the devices as well as the network communications to a virtual time plane while retaining full fidelity. At themore » core of our framework is a scheduling engine that operates at the level of a hypervisor scheduler, offering a unique ability to execute multi-core guest nodes over multi-core host nodes in an accurate, virtual time-synchronized manner. In contrast to other related approaches that suffer from either speed or accuracy issues, our framework provides MANET node-wise scalability, high fidelity of software behaviors, and time-ordering accuracy. The design and development of this framework is presented, and an ac-tual implementation based on the widely used Xen hypervisor system is described. Benchmarks with synthetic and actual applications are used to identify the benefits of our approach. The time inaccuracy of traditional emulation methods is demonstrated, in comparison with the accurate execution of our framework verified by theoretically correct results expected from analytical models of the same scenarios. In the largest high fidelity tests, we are able to perform virtual time-synchronized simulation of 64-node VM-based full-stack, actual software behaviors of MANETs containing a mix of static and mobile (unmanned airborne vehicle) nodes, hosted on a 32-core host, with full fidelity of unmodified ad-hoc routing protocols, unmodified

  4. An Energy-Efficient and Robust Multipath Routing Protocol for Cognitive Radio Ad Hoc Networks.

    PubMed

    Singh, Kishor; Moh, Sangman

    2017-09-04

    Routing in cognitive radio ad hoc networks (CRAHNs) is a daunting task owing to dynamic topology, intermittent connectivity, spectrum heterogeneity, and energy constraints. Other prominent aspects such as channel stability, path reliability, and route discovery frequency should also be exploited. Several routing protocols have been proposed for CRAHNs in the literature. By stressing on one of the aspects more than any other, however, they do not satisfy all requirements of throughput, energy efficiency, and robustness. In this paper, we propose an energy-efficient and robust multipath routing (ERMR) protocol for CRAHNs by considering all prominent aspects including residual energy and channel stability in design. Even when the current routing path fails, the alternative routing path is immediately utilized. In establishing primary and alternative routing paths, both residual energy and channel stability are exploited simultaneously. Our simulation study shows that the proposed ERMR outperforms the conventional protocol in terms of network throughput, packet delivery ratio, energy consumption, and end-to-end delay.

  5. An Energy-Efficient and Robust Multipath Routing Protocol for Cognitive Radio Ad Hoc Networks

    PubMed Central

    Singh, Kishor

    2017-01-01

    Routing in cognitive radio ad hoc networks (CRAHNs) is a daunting task owing to dynamic topology, intermittent connectivity, spectrum heterogeneity, and energy constraints. Other prominent aspects such as channel stability, path reliability, and route discovery frequency should also be exploited. Several routing protocols have been proposed for CRAHNs in the literature. By stressing on one of the aspects more than any other, however, they do not satisfy all requirements of throughput, energy efficiency, and robustness. In this paper, we propose an energy-efficient and robust multipath routing (ERMR) protocol for CRAHNs by considering all prominent aspects including residual energy and channel stability in design. Even when the current routing path fails, the alternative routing path is immediately utilized. In establishing primary and alternative routing paths, both residual energy and channel stability are exploited simultaneously. Our simulation study shows that the proposed ERMR outperforms the conventional protocol in terms of network throughput, packet delivery ratio, energy consumption, and end-to-end delay. PMID:28869551

  6. On using multiple routing metrics with destination sequenced distance vector protocol for MultiHop wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Mehic, M.; Fazio, P.; Voznak, M.; Partila, P.; Komosny, D.; Tovarek, J.; Chmelikova, Z.

    2016-05-01

    A mobile ad hoc network is a collection of mobile nodes which communicate without a fixed backbone or centralized infrastructure. Due to the frequent mobility of nodes, routes connecting two distant nodes may change. Therefore, it is not possible to establish a priori fixed paths for message delivery through the network. Because of its importance, routing is the most studied problem in mobile ad hoc networks. In addition, if the Quality of Service (QoS) is demanded, one must guarantee the QoS not only over a single hop but over an entire wireless multi-hop path which may not be a trivial task. In turns, this requires the propagation of QoS information within the network. The key to the support of QoS reporting is QoS routing, which provides path QoS information at each source. To support QoS for real-time traffic one needs to know not only minimum delay on the path to the destination but also the bandwidth available on it. Therefore, throughput, end-to-end delay, and routing overhead are traditional performance metrics used to evaluate the performance of routing protocol. To obtain additional information about the link, most of quality-link metrics are based on calculation of the lost probabilities of links by broadcasting probe packets. In this paper, we address the problem of including multiple routing metrics in existing routing packets that are broadcasted through the network. We evaluate the efficiency of such approach with modified version of DSDV routing protocols in ns-3 simulator.

  7. On mobile wireless ad hoc IP video transports

    NASA Astrophysics Data System (ADS)

    Kazantzidis, Matheos

    2006-05-01

    Multimedia transports in wireless, ad-hoc, multi-hop or mobile networks must be capable of obtaining information about the network and adaptively tune sending and encoding parameters to the network response. Obtaining meaningful metrics to guide a stable congestion control mechanism in the transport (i.e. passive, simple, end-to-end and network technology independent) is a complex problem. Equally difficult is obtaining a reliable QoS metrics that agrees with user perception in a client/server or distributed environment. Existing metrics, objective or subjective, are commonly used after or before to test or report on a transmission and require access to both original and transmitted frames. In this paper, we propose that an efficient and successful video delivery and the optimization of overall network QoS requires innovation in a) a direct measurement of available and bottleneck capacity for its congestion control and b) a meaningful subjective QoS metric that is dynamically reported to video sender. Once these are in place, a binomial -stable, fair and TCP friendly- algorithm can be used to determine the sending rate and other packet video parameters. An adaptive mpeg codec can then continually test and fit its parameters and temporal-spatial data-error control balance using the perceived QoS dynamic feedback. We suggest a new measurement based on a packet dispersion technique that is independent of underlying network mechanisms. We then present a binomial control based on direct measurements. We implement a QoS metric that is known to agree with user perception (MPQM) in a client/server, distributed environment by using predetermined table lookups and characterization of video content.

  8. Hierarchical auto-configuration addressing in mobile ad hoc networks (HAAM)

    NASA Astrophysics Data System (ADS)

    Ram Srikumar, P.; Sumathy, S.

    2017-11-01

    Addressing plays a vital role in networking to identify devices uniquely. A device must be assigned with a unique address in order to participate in the data communication in any network. Different protocols defining different types of addressing are proposed in literature. Address auto-configuration is a key requirement for self organizing networks. Existing auto-configuration based addressing protocols require broadcasting probes to all the nodes in the network before assigning a proper address to a new node. This needs further broadcasts to reflect the status of the acquired address in the network. Such methods incur high communication overheads due to repetitive flooding. To address this overhead, a new partially stateful address allocation scheme, namely Hierarchical Auto-configuration Addressing (HAAM) scheme is extended and proposed. Hierarchical addressing basically reduces latency and overhead caused during address configuration. Partially stateful addressing algorithm assigns addresses without the need for flooding and global state awareness, which in turn reduces the communication overhead and space complexity respectively. Nodes are assigned addresses hierarchically to maintain the graph of the network as a spanning tree which helps in effectively avoiding the broadcast storm problem. Proposed algorithm for HAAM handles network splits and merges efficiently in large scale mobile ad hoc networks incurring low communication overheads.

  9. Performance Improvement in Geographic Routing for Vehicular Ad Hoc Networks

    PubMed Central

    Kaiwartya, Omprakash; Kumar, Sushil; Lobiyal, D. K.; Abdullah, Abdul Hanan; Hassan, Ahmed Nazar

    2014-01-01

    Geographic routing is one of the most investigated themes by researchers for reliable and efficient dissemination of information in Vehicular Ad Hoc Networks (VANETs). Recently, different Geographic Distance Routing (GEDIR) protocols have been suggested in the literature. These protocols focus on reducing the forwarding region towards destination to select the Next Hop Vehicles (NHV). Most of these protocols suffer from the problem of elevated one-hop link disconnection, high end-to-end delay and low throughput even at normal vehicle speed in high vehicle density environment. This paper proposes a Geographic Distance Routing protocol based on Segment vehicle, Link quality and Degree of connectivity (SLD-GEDIR). The protocol selects a reliable NHV using the criteria segment vehicles, one-hop link quality and degree of connectivity. The proposed protocol has been simulated in NS-2 and its performance has been compared with the state-of-the-art protocols: P-GEDIR, J-GEDIR and V-GEDIR. The empirical results clearly reveal that SLD-GEDIR has lower link disconnection and end-to-end delay, and higher throughput as compared to the state-of-the-art protocols. It should be noted that the performance of the proposed protocol is preserved irrespective of vehicle density and speed. PMID:25429415

  10. Performance improvement in geographic routing for Vehicular Ad Hoc Networks.

    PubMed

    Kaiwartya, Omprakash; Kumar, Sushil; Lobiyal, D K; Abdullah, Abdul Hanan; Hassan, Ahmed Nazar

    2014-11-25

    Geographic routing is one of the most investigated themes by researchers for reliable and efficient dissemination of information in Vehicular Ad Hoc Networks (VANETs). Recently, different Geographic Distance Routing (GEDIR) protocols have been suggested in the literature. These protocols focus on reducing the forwarding region towards destination to select the Next Hop Vehicles (NHV). Most of these protocols suffer from the problem of elevated one-hop link disconnection, high end-to-end delay and low throughput even at normal vehicle speed in high vehicle density environment. This paper proposes a Geographic Distance Routing protocol based on Segment vehicle, Link quality and Degree of connectivity (SLD-GEDIR). The protocol selects a reliable NHV using the criteria segment vehicles, one-hop link quality and degree of connectivity. The proposed protocol has been simulated in NS-2 and its performance has been compared with the state-of-the-art protocols: P-GEDIR, J-GEDIR and V-GEDIR. The empirical results clearly reveal that SLD-GEDIR has lower link disconnection and end-to-end delay, and higher throughput as compared to the state-of-the-art protocols. It should be noted that the performance of the proposed protocol is preserved irrespective of vehicle density and speed.

  11. Preserving Nevada's Environmental Heritage: A Report of the Ad Hoc Committee on Environmental Quality. Final Report to the Governor's Natural Resources Council.

    ERIC Educational Resources Information Center

    Nevada State Dept. of Conservation and Natural Resources, Carson City.

    The Environmental Quality Ad Hoc Committee has prepared this report for the Governor's Natural Resources Council (Nevada). It is a compilation of available factual data focusing attention on needed statutory and administrative changes to preserve Nevada's environmental heritage and from which recommendations for future budgetary and legislative…

  12. A novel unbalanced multiple description coder for robust video transmission over ad hoc wireless networks

    NASA Astrophysics Data System (ADS)

    Huang, Feng; Sun, Lifeng; Zhong, Yuzhuo

    2006-01-01

    Robust transmission of live video over ad hoc wireless networks presents new challenges: high bandwidth requirements are coupled with delay constraints; even a single packet loss causes error propagation until a complete video frame is coded in the intra-mode; ad hoc wireless networks suffer from bursty packet losses that drastically degrade the viewing experience. Accordingly, we propose a novel UMD coder capable of quickly recovering from losses and ensuring continuous playout. It uses 'peg' frames to prevent error propagation in the High-Resolution (HR) description and improve the robustness of key frames. The Low-Resolution (LR) coder works independent of the HR one, but they can also help each other recover from losses. Like many UMD coders, our UMD coder is drift-free, disruption-tolerant and able to make good use of the asymmetric available bandwidths of multiple paths. The simulation results under different conditions show that the proposed UMD coder has the highest decoded quality and lowest probability of pause when compared with concurrent UMDC techniques. The coder also has a comparable decoded quality, lower startup delay and lower probability of pause than a state-of-the-art FEC-based scheme. To provide robustness for video multicast applications, we propose non-end-to-end UMDC-based video distribution over a multi-tree multicast network. The multiplicity of parents decorrelates losses and the non-end-to-end feature increases the throughput of UMDC video data. We deploy an application-level service of LR description reconstruction in some intermediate nodes of the LR multicast tree. The principle behind this is to reconstruct the disrupted LR frames by the correctly received HR frames. As a result, the viewing experience at the downstream nodes benefits from the protection reconstruction at the upstream nodes.

  13. Modern Foreign Language Teachers--Don't Leave Those Kids Alone! Linguistic-Cultural "Give and Take" in an Ad-Hoc Tutoring Scheme

    ERIC Educational Resources Information Center

    Leroy, Norah

    2017-01-01

    This paper addresses the theme of social inclusion through language learning. The focus is on an ad-hoc tutoring scheme set up between newly arrived British migrant pupils and French monolingual pupils in a small secondary school in the south-west of France. Though the original objective of this tutoring scheme was to improve the English skills of…

  14. Use of synthesized data to support complex ad-hoc queries in an enterprise information warehouse: a diabetes use case.

    PubMed

    Rogers, Patrick; Erdal, Selnur; Santangelo, Jennifer; Liu, Jianhua; Schuster, Dara; Kamal, Jyoti

    2008-11-06

    The Ohio State University Medical Center (OSUMC) Information Warehouse (IW) is a comprehensive data warehousing facility incorporating operational, clinical, and biological data sets from multiple enterprise system. It is common for users of the IW to request complex ad-hoc queries that often require significant intervention by data analyst. In response to this challenge, we have designed a workflow that leverages synthesized data elements to support such queries in an more timely, efficient manner.

  15. Adaptive Control Parameters for Dispersal of Multi-Agent Mobile Ad Hoc Network (MANET) Swarms

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kurt Derr; Milos Manic

    A mobile ad hoc network is a collection of independent nodes that communicate wirelessly with one another. This paper investigates nodes that are swarm robots with communications and sensing capabilities. Each robot in the swarm may operate in a distributed and decentralized manner to achieve some goal. This paper presents a novel approach to dynamically adapting control parameters to achieve mesh configuration stability. The presented approach to robot interaction is based on spring force laws (attraction and repulsion laws) to create near-optimal mesh like configurations. In prior work, we presented the extended virtual spring mesh (EVSM) algorithm for the dispersionmore » of robot swarms. This paper extends the EVSM framework by providing the first known study on the effects of adaptive versus static control parameters on robot swarm stability. The EVSM algorithm provides the following novelties: 1) improved performance with adaptive control parameters and 2) accelerated convergence with high formation effectiveness. Simulation results show that 120 robots reach convergence using adaptive control parameters more than twice as fast as with static control parameters in a multiple obstacle environment.« less

  16. The Copyright Law as it Relates to National Information Systems and National Programs; a Study by the Ad Hoc Task Group on Legal Aspects Involved in National Information Systems.

    ERIC Educational Resources Information Center

    Federal Council for Science and Technology, Washington, DC. Committee on Scientific and Technical Information.

    An ad hoc task group was constituted by the Committee on Scientific and Technical Information (COSATI) to: (1) delineate present and future issues issues for COSATI, (3) recommend additions or deletions in the present copyright law or in the pending revision now in Congress, and (4) recommend other short or long-term actions related to authorship…

  17. Securing mobile ad hoc networks using danger theory-based artificial immune algorithm.

    PubMed

    Abdelhaq, Maha; Alsaqour, Raed; Abdelhaq, Shawkat

    2015-01-01

    A mobile ad hoc network (MANET) is a set of mobile, decentralized, and self-organizing nodes that are used in special cases, such as in the military. MANET properties render the environment of this network vulnerable to different types of attacks, including black hole, wormhole and flooding-based attacks. Flooding-based attacks are one of the most dangerous attacks that aim to consume all network resources and thus paralyze the functionality of the whole network. Therefore, the objective of this paper is to investigate the capability of a danger theory-based artificial immune algorithm called the mobile dendritic cell algorithm (MDCA) to detect flooding-based attacks in MANETs. The MDCA applies the dendritic cell algorithm (DCA) to secure the MANET with additional improvements. The MDCA is tested and validated using Qualnet v7.1 simulation tool. This work also introduces a new simulation module for a flooding attack called the resource consumption attack (RCA) using Qualnet v7.1. The results highlight the high efficiency of the MDCA in detecting RCAs in MANETs.

  18. Securing Mobile Ad Hoc Networks Using Danger Theory-Based Artificial Immune Algorithm

    PubMed Central

    2015-01-01

    A mobile ad hoc network (MANET) is a set of mobile, decentralized, and self-organizing nodes that are used in special cases, such as in the military. MANET properties render the environment of this network vulnerable to different types of attacks, including black hole, wormhole and flooding-based attacks. Flooding-based attacks are one of the most dangerous attacks that aim to consume all network resources and thus paralyze the functionality of the whole network. Therefore, the objective of this paper is to investigate the capability of a danger theory-based artificial immune algorithm called the mobile dendritic cell algorithm (MDCA) to detect flooding-based attacks in MANETs. The MDCA applies the dendritic cell algorithm (DCA) to secure the MANET with additional improvements. The MDCA is tested and validated using Qualnet v7.1 simulation tool. This work also introduces a new simulation module for a flooding attack called the resource consumption attack (RCA) using Qualnet v7.1. The results highlight the high efficiency of the MDCA in detecting RCAs in MANETs. PMID:25946001

  19. Medium Access Control Protocols for Cognitive Radio Ad Hoc Networks: A Survey

    PubMed Central

    Islam, A. K. M. Muzahidul; Baharun, Sabariah; Mansoor, Nafees

    2017-01-01

    New wireless network paradigms will demand higher spectrum use and availability to cope with emerging data-hungry devices. Traditional static spectrum allocation policies cause spectrum scarcity, and new paradigms such as Cognitive Radio (CR) and new protocols and techniques need to be developed in order to have efficient spectrum usage. Medium Access Control (MAC) protocols are accountable for recognizing free spectrum, scheduling available resources and coordinating the coexistence of heterogeneous systems and users. This paper provides an ample review of the state-of-the-art MAC protocols, which mainly focuses on Cognitive Radio Ad Hoc Networks (CRAHN). First, a description of the cognitive radio fundamental functions is presented. Next, MAC protocols are divided into three groups, which are based on their channel access mechanism, namely time-slotted protocol, random access protocol and hybrid protocol. In each group, a detailed and comprehensive explanation of the latest MAC protocols is presented, as well as the pros and cons of each protocol. A discussion on future challenges for CRAHN MAC protocols is included with a comparison of the protocols from a functional perspective. PMID:28926952

  20. 3VSR: Three Valued Secure Routing for Vehicular Ad Hoc Networks using Sensing Logic in Adversarial Environment

    PubMed Central

    Wang, Liangmin

    2018-01-01

    Today IoT integrate thousands of inter networks and sensing devices e.g., vehicular networks, which are considered to be challenging due to its high speed and network dynamics. The goal of future vehicular networks is to improve road safety, promote commercial or infotainment products and to reduce the traffic accidents. All these applications are based on the information exchange among nodes, so not only reliable data delivery but also the authenticity and credibility of the data itself are prerequisite. To cope with the aforementioned problem, trust management come up as promising candidate to conduct node’s transaction and interaction management, which requires distributed mobile nodes cooperation for achieving design goals. In this paper, we propose a trust-based routing protocol i.e., 3VSR (Three Valued Secure Routing), which extends the widely used AODV (Ad hoc On-demand Distance Vector) routing protocol and employs the idea of Sensing Logic-based trust model to enhance the security solution of VANET (Vehicular Ad-Hoc Network). The existing routing protocol are mostly based on key or signature-based schemes, which off course increases computation overhead. In our proposed 3VSR, trust among entities is updated frequently by means of opinion derived from sensing logic due to vehicles random topologies. In 3VSR the theoretical capabilities are based on Dirichlet distribution by considering prior and posterior uncertainty of the said event. Also by using trust recommendation message exchange, nodes are able to reduce computation and routing overhead. The simulated results shows that the proposed scheme is secure and practical. PMID:29538314

  1. 3VSR: Three Valued Secure Routing for Vehicular Ad Hoc Networks using Sensing Logic in Adversarial Environment.

    PubMed

    Sohail, Muhammad; Wang, Liangmin

    2018-03-14

    Today IoT integrate thousands of inter networks and sensing devices e.g., vehicular networks, which are considered to be challenging due to its high speed and network dynamics. The goal of future vehicular networks is to improve road safety, promote commercial or infotainment products and to reduce the traffic accidents. All these applications are based on the information exchange among nodes, so not only reliable data delivery but also the authenticity and credibility of the data itself are prerequisite. To cope with the aforementioned problem, trust management come up as promising candidate to conduct node's transaction and interaction management, which requires distributed mobile nodes cooperation for achieving design goals. In this paper, we propose a trust-based routing protocol i.e., 3VSR (Three Valued Secure Routing), which extends the widely used AODV (Ad hoc On-demand Distance Vector) routing protocol and employs the idea of Sensing Logic-based trust model to enhance the security solution of VANET (Vehicular Ad-Hoc Network). The existing routing protocol are mostly based on key or signature-based schemes, which off course increases computation overhead. In our proposed 3VSR, trust among entities is updated frequently by means of opinion derived from sensing logic due to vehicles random topologies. In 3VSR the theoretical capabilities are based on Dirichlet distribution by considering prior and posterior uncertainty of the said event. Also by using trust recommendation message exchange, nodes are able to reduce computation and routing overhead. The simulated results shows that the proposed scheme is secure and practical.

  2. Hop Optimization and Relay Node Selection in Multi-hop Wireless Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Li, Xiaohua(Edward)

    In this paper we propose an efficient approach to determine the optimal hops for multi-hop ad hoc wireless networks. Based on the assumption that nodes use successive interference cancellation (SIC) and maximal ratio combining (MRC) to deal with mutual interference and to utilize all the received signal energy, we show that the signal-to-interference-plus-noise ratio (SINR) of a node is determined only by the nodes before it, not the nodes after it, along a packet forwarding path. Based on this observation, we propose an iterative procedure to select the relay nodes and to calculate the path SINR as well as capacity of an arbitrary multi-hop packet forwarding path. The complexity of the algorithm is extremely low, and scaling well with network size. The algorithm is applicable in arbitrarily large networks. Its performance is demonstrated as desirable by simulations. The algorithm can be helpful in analyzing the performance of multi-hop wireless networks.

  3. A communication theoretical analysis of FRET-based mobile ad hoc molecular nanonetworks.

    PubMed

    Kuscu, Murat; Akan, Ozgur B

    2014-09-01

    Nanonetworks refer to a group of nanosized machines with very basic operational capabilities communicating to each other in order to accomplish more complex tasks such as in-body drug delivery, or chemical defense. Realizing reliable and high-rate communication between these nanomachines is a fundamental problem for the practicality of these nanonetworks. Recently, we have proposed a molecular communication method based on Förster Resonance Energy Transfer (FRET) which is a nonradiative excited state energy transfer phenomenon observed among fluorescent molecules, i.e., fluorophores. We have modeled the FRET-based communication channel considering the fluorophores as single-molecular immobile nanomachines, and shown its reliability at high rates, and practicality at the current stage of nanotechnology. In this study, for the first time in the literature, we investigate the network of mobile nanomachines communicating through FRET. We introduce two novel mobile molecular nanonetworks: FRET-based mobile molecular sensor/actor nanonetwork (FRET-MSAN) which is a distributed system of mobile fluorophores acting as sensor or actor node; and FRET-based mobile ad hoc molecular nanonetwork (FRET-MAMNET) which consists of fluorophore-based nanotransmitter, nanoreceivers and nanorelays. We model the single message propagation based on birth-death processes with continuous time Markov chains. We evaluate the performance of FRET-MSAN and FRET-MAMNET in terms of successful transmission probability and mean extinction time of the messages, system throughput, channel capacity and achievable communication rates.

  4. Real-Time Support on IEEE 802.11 Wireless Ad-Hoc Networks: Reality vs. Theory

    NASA Astrophysics Data System (ADS)

    Kang, Mikyung; Kang, Dong-In; Suh, Jinwoo

    The usable throughput of an IEEE 802.11 system for an application is much less than the raw bandwidth. Although 802.11b has a theoretical maximum of 11Mbps, more than half of the bandwidth is consumed by overhead leaving at most 5Mbps of usable bandwidth. Considering this characteristic, this paper proposes and analyzes a real-time distributed scheduling scheme based on the existing IEEE 802.11 wireless ad-hoc networks, using USC/ISI's Power Aware Sensing Tracking and Analysis (PASTA) hardware platform. We compared the distributed real-time scheduling scheme with the real-time polling scheme to meet deadline, and compared a measured real bandwidth with a theoretical result. The theoretical and experimental results show that the distributed scheduling scheme can guarantee real-time traffic and enhances the performance up to 74% compared with polling scheme.

  5. An Ad-hoc Satellite Network to Measure Filamentary Current Structures in the Auroral Zone

    NASA Astrophysics Data System (ADS)

    Nabong, C.; Fritz, T. A.; Semeter, J. L.

    2014-12-01

    An ad-hoc cubesat-based satellite network project known as ANDESITE is under development at Boston University. It aims to develop a dense constellation of easy-to-use, rapidly-deployable low-cost wireless sensor nodes in space. The objectives of the project are threefold: 1) Demonstrate viability of satellite based sensor networks by deploying an 8-node miniature sensor network to study the filamentation of the field aligned currents in the auroral zones of the Earth's magnetosphere. 2) Test the scalability of proposed protocols, including localization techniques, tracking, data aggregation, and routing, for a 3 dimensional wireless sensor network using a "flock" of nodes. 3) Construct a 6U Cube-sat running the Android OS as an integrated constellation manager, data mule and sensor node deplorer. This small network of sensor nodes will resolve current densities at different spatial resolutions in the near-Earth magnetosphere using measurements from magnetometers with 1-nT sensitivities and 0.2 nT/√Hz self-noise. Mapping of these currents will provide new constraints for models of auroral particle acceleration, wave-particle interactions, ionospheric destabilization, and other kinetic processes operating in the low-beta plasma of the near Earth magnetosphere.

  6. A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks

    PubMed Central

    Chen, Huifang; Ge, Linlin; Xie, Lei

    2015-01-01

    The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes. PMID:26184224

  7. A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks.

    PubMed

    Chen, Huifang; Ge, Linlin; Xie, Lei

    2015-07-14

    The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes.

  8. Pseudo-random dynamic address configuration (PRDAC) algorithm for mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Wu, Shaochuan; Tan, Xuezhi

    2007-11-01

    By analyzing all kinds of address configuration algorithms, this paper provides a new pseudo-random dynamic address configuration (PRDAC) algorithm for mobile ad hoc networks. Based on PRDAC, the first node that initials this network randomly chooses a nonlinear shift register that can generates an m-sequence. When another node joins this network, the initial node will act as an IP address configuration sever to compute an IP address according to this nonlinear shift register, and then allocates this address and tell the generator polynomial of this shift register to this new node. By this means, when other node joins this network, any node that has obtained an IP address can act as a server to allocate address to this new node. PRDAC can also efficiently avoid IP conflicts and deal with network partition and merge as same as prophet address (PA) allocation and dynamic configuration and distribution protocol (DCDP). Furthermore, PRDAC has less algorithm complexity, less computational complexity and more sufficient assumption than PA. In addition, PRDAC radically avoids address conflicts and maximizes the utilization rate of IP addresses. Analysis and simulation results show that PRDAC has rapid convergence, low overhead and immune from topological structures.

  9. Optimal route discovery for soft QOS provisioning in mobile ad hoc multimedia networks

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Pan, Feng

    2007-09-01

    In this paper, we propose an optimal routing discovery algorithm for ad hoc multimedia networks whose resource keeps changing, First, we use stochastic models to measure the network resource availability, based on the information about the location and moving pattern of the nodes, as well as the link conditions between neighboring nodes. Then, for a certain multimedia packet flow to be transmitted from a source to a destination, we formulate the optimal soft-QoS provisioning problem as to find the best route that maximize the probability of satisfying its desired QoS requirements in terms of the maximum delay constraints. Based on the stochastic network resource model, we developed three approaches to solve the formulated problem: A centralized approach serving as the theoretical reference, a distributed approach that is more suitable to practical real-time deployment, and a distributed dynamic approach that utilizes the updated time information to optimize the routing for each individual packet. Examples of numerical results demonstrated that using the route discovered by our distributed algorithm in a changing network environment, multimedia applications could achieve better QoS statistically.

  10. Energy-efficient algorithm for broadcasting in ad hoc wireless sensor networks.

    PubMed

    Xiong, Naixue; Huang, Xingbo; Cheng, Hongju; Wan, Zheng

    2013-04-12

    Broadcasting is a common and basic operation used to support various network protocols in wireless networks. To achieve energy-efficient broadcasting is especially important for ad hoc wireless sensor networks because sensors are generally powered by batteries with limited lifetimes. Energy consumption for broadcast operations can be reduced by minimizing the number of relay nodes based on the observation that data transmission processes consume more energy than data reception processes in the sensor nodes, and how to improve the network lifetime is always an interesting issue in sensor network research. The minimum-energy broadcast problem is then equivalent to the problem of finding the minimum Connected Dominating Set (CDS) for a connected graph that is proved NP-complete. In this paper, we introduce an Efficient Minimum CDS algorithm (EMCDS) with help of a proposed ordered sequence list. EMCDS does not concern itself with node energy and broadcast operations might fail if relay nodes are out of energy. Next we have proposed a Minimum Energy-consumption Broadcast Scheme (MEBS) with a modified version of EMCDS, and aimed at providing an efficient scheduling scheme with maximized network lifetime. The simulation results show that the proposed EMCDS algorithm can find smaller CDS compared with related works, and the MEBS can help to increase the network lifetime by efficiently balancing energy among nodes in the networks.

  11. A DNA-Inspired Encryption Methodology for Secure, Mobile Ad Hoc Networks

    NASA Technical Reports Server (NTRS)

    Shaw, Harry

    2012-01-01

    Users are pushing for greater physical mobility with their network and Internet access. Mobile ad hoc networks (MANET) can provide an efficient mobile network architecture, but security is a key concern. A figure summarizes differences in the state of network security for MANET and fixed networks. MANETs require the ability to distinguish trusted peers, and tolerate the ingress/egress of nodes on an unscheduled basis. Because the networks by their very nature are mobile and self-organizing, use of a Public Key Infra structure (PKI), X.509 certificates, RSA, and nonce ex changes becomes problematic if the ideal of MANET is to be achieved. Molecular biology models such as DNA evolution can provide a basis for a proprietary security architecture that achieves high degrees of diffusion and confusion, and resistance to cryptanalysis. A proprietary encryption mechanism was developed that uses the principles of DNA replication and steganography (hidden word cryptography) for confidentiality and authentication. The foundation of the approach includes organization of coded words and messages using base pairs organized into genes, an expandable genome consisting of DNA-based chromosome keys, and a DNA-based message encoding, replication, and evolution and fitness. In evolutionary computing, a fitness algorithm determines whether candidate solutions, in this case encrypted messages, are sufficiently encrypted to be transmitted. The technology provides a mechanism for confidential electronic traffic over a MANET without a PKI for authenticating users.

  12. A Game Theory Algorithm for Intra-Cluster Data Aggregation in a Vehicular Ad Hoc Network

    PubMed Central

    Chen, Yuzhong; Weng, Shining; Guo, Wenzhong; Xiong, Naixue

    2016-01-01

    Vehicular ad hoc networks (VANETs) have an important role in urban management and planning. The effective integration of vehicle information in VANETs is critical to traffic analysis, large-scale vehicle route planning and intelligent transportation scheduling. However, given the limitations in the precision of the output information of a single sensor and the difficulty of information sharing among various sensors in a highly dynamic VANET, effectively performing data aggregation in VANETs remains a challenge. Moreover, current studies have mainly focused on data aggregation in large-scale environments but have rarely discussed the issue of intra-cluster data aggregation in VANETs. In this study, we propose a multi-player game theory algorithm for intra-cluster data aggregation in VANETs by analyzing the competitive and cooperative relationships among sensor nodes. Several sensor-centric metrics are proposed to measure the data redundancy and stability of a cluster. We then study the utility function to achieve efficient intra-cluster data aggregation by considering both data redundancy and cluster stability. In particular, we prove the existence of a unique Nash equilibrium in the game model, and conduct extensive experiments to validate the proposed algorithm. Results demonstrate that the proposed algorithm has advantages over typical data aggregation algorithms in both accuracy and efficiency. PMID:26907272

  13. A Game Theory Algorithm for Intra-Cluster Data Aggregation in a Vehicular Ad Hoc Network.

    PubMed

    Chen, Yuzhong; Weng, Shining; Guo, Wenzhong; Xiong, Naixue

    2016-02-19

    Vehicular ad hoc networks (VANETs) have an important role in urban management and planning. The effective integration of vehicle information in VANETs is critical to traffic analysis, large-scale vehicle route planning and intelligent transportation scheduling. However, given the limitations in the precision of the output information of a single sensor and the difficulty of information sharing among various sensors in a highly dynamic VANET, effectively performing data aggregation in VANETs remains a challenge. Moreover, current studies have mainly focused on data aggregation in large-scale environments but have rarely discussed the issue of intra-cluster data aggregation in VANETs. In this study, we propose a multi-player game theory algorithm for intra-cluster data aggregation in VANETs by analyzing the competitive and cooperative relationships among sensor nodes. Several sensor-centric metrics are proposed to measure the data redundancy and stability of a cluster. We then study the utility function to achieve efficient intra-cluster data aggregation by considering both data redundancy and cluster stability. In particular, we prove the existence of a unique Nash equilibrium in the game model, and conduct extensive experiments to validate the proposed algorithm. Results demonstrate that the proposed algorithm has advantages over typical data aggregation algorithms in both accuracy and efficiency.

  14. Ad hoc versus standardized admixtures for continuous infusion drugs in neonatal intensive care: cognitive task analysis of safety at the bedside.

    PubMed

    Brannon, Timothy S

    2006-01-01

    Continuous infusion intravenous (IV) drugs in neonatal intensive care are usually prepared based on patient weight so that the dose is readable as a simple multiple of the infusion pump rate. New safety guidelines propose that hospitals switch to using standardized admixtures of these drugs to prevent calculation errors during ad hoc preparation. Extended hierarchical task analysis suggests that switching to standardized admixtures may lead to more errors in programming the pump at the bedside.

  15. Verifying Safety Messages Using Relative-Time and Zone Priority in Vehicular Ad Hoc Networks.

    PubMed

    Banani, Sam; Gordon, Steven; Thiemjarus, Surapa; Kittipiyakul, Somsak

    2018-04-13

    In high-density road networks, with each vehicle broadcasting multiple messages per second, the arrival rate of safety messages can easily exceed the rate at which digital signatures can be verified. Since not all messages can be verified, algorithms for selecting which messages to verify are required to ensure that each vehicle receives appropriate awareness about neighbouring vehicles. This paper presents a novel scheme to select important safety messages for verification in vehicular ad hoc networks (VANETs). The proposed scheme uses location and direction of the sender, as well as proximity and relative-time between vehicles, to reduce the number of irrelevant messages verified (i.e., messages from vehicles that are unlikely to cause an accident). Compared with other existing schemes, the analysis results show that the proposed scheme can verify messages from nearby vehicles with lower inter-message delay and reduced packet loss and thus provides high level of awareness of the nearby vehicles.

  16. Verifying Safety Messages Using Relative-Time and Zone Priority in Vehicular Ad Hoc Networks

    PubMed Central

    Banani, Sam; Thiemjarus, Surapa; Kittipiyakul, Somsak

    2018-01-01

    In high-density road networks, with each vehicle broadcasting multiple messages per second, the arrival rate of safety messages can easily exceed the rate at which digital signatures can be verified. Since not all messages can be verified, algorithms for selecting which messages to verify are required to ensure that each vehicle receives appropriate awareness about neighbouring vehicles. This paper presents a novel scheme to select important safety messages for verification in vehicular ad hoc networks (VANETs). The proposed scheme uses location and direction of the sender, as well as proximity and relative-time between vehicles, to reduce the number of irrelevant messages verified (i.e., messages from vehicles that are unlikely to cause an accident). Compared with other existing schemes, the analysis results show that the proposed scheme can verify messages from nearby vehicles with lower inter-message delay and reduced packet loss and thus provides high level of awareness of the nearby vehicles. PMID:29652840

  17. Ad Hoc versus Standardized Admixtures for Continuous Infusion Drugs in Neonatal Intensive Care: Cognitive Task Analysis of Safety at the Bedside

    PubMed Central

    Brannon, Timothy S.

    2006-01-01

    Continuous infusion intravenous (IV) drugs in neonatal intensive care are usually prepared based on patient weight so that the dose is readable as a simple multiple of the infusion pump rate. New safety guidelines propose that hospitals switch to using standardized admixtures of these drugs to prevent calculation errors during ad hoc preparation. Extended hierarchical task analysis suggests that switching to standardized admixtures may lead to more errors in programming the pump at the bedside. PMID:17238482

  18. Ad Hoc Networking for Unmanned Ground Vehicles: Design and Evaluation at Command, Control, Communications, Intelligence, Surveillance and Reconnaissance On-the-Move

    DTIC Science & Technology

    2006-11-01

    software components used in the ad hoc nodes for the C4ISR OTM experiment were OLSRD, an open-source proactive MANET routing software, and OpenVPN , an...developed by Mike Baker (openwrt.org). 6OpenVPN is a trademark of OpenVPN Solutions LLC. 6 Secure communications in the MANET are achieved with...encryption provided by Wired Equivalent Privacy (WEP) and OpenVPN . The WEP protocol, which is part of the IEEE 802.11 wireless networking standard

  19. Ad Hoc working group on diurnal and semi-diurnal Earth Orientation variation.

    NASA Astrophysics Data System (ADS)

    Gipson, J. M.

    2017-12-01

    Diurnal and semi-diurnal Earth orientation ("HF-EOP") variation were detected in the early 1990s in SLR and VLBI data. Beginning in 1996 a model of HF-EOP variation based on ocean-tides derived from Topex data was included in the IERS standards. This model has not been updated since then with the exception of including libration for effects for polar motion (2003 IERS conventions) and UT1 (2010 IERS conventions). The accuracy of Space Geodesy has increased remarkably over the last 20 years and the 1996 IERS HF-EOP model is no longer adequate. At the conclusion of the 2017 GGOS/IERS Unified Analysis Workshop an ad hoc working group was formed including representatives of the IDS, IGS, ILRS, and IVS. The goal of the working group is to test several models of HF-EOP in the different space geodesy techniques and to make a recommendation to the IERS for the adoption of a new HF-EOP model. In this presentation I will give a summary of work on HF-EOP done to date by various scientists which demonstrate the inadequacy of the current IERS HF-EOP model. I will then describe the goals and the progress of the working group to date, with a preview of further work.

  20. An ultra-wide bandwidth-based range/GPS tight integration approach for relative positioning in vehicular ad hoc networks

    NASA Astrophysics Data System (ADS)

    Shen, Feng; Wayn Cheong, Joon; Dempster, Andrew G.

    2015-04-01

    Relative position awareness is a vital premise for the implementation of emerging intelligent transportation systems, such as collision warning. However, commercial global navigation satellite systems (GNSS) receivers do not satisfy the requirements of these applications. Fortunately, cooperative positioning (CP) techniques, through sharing the GNSS measurements between vehicles, can improve the performance of relative positioning in a vehicular ad hoc network (VANET). In this paper, while assuming there are no obstacles between vehicles, a new enhanced tightly coupled CP technique is presented by adding ultra-wide bandwidth (UWB)-based inter-vehicular range measurements. In the proposed CP method, each vehicle fuses the GPS measurements and the inter-vehicular range measurements. Based on analytical and experimental results, in the full GPS coverage environment, the new tight integration CP method outperforms the INS-aided tight CP method, tight CP method, and DGPS by 11%, 15%, and 24%, respectively; in the GPS outage scenario, the performance improvement achieves 60%, 65%, and 73%, respectively.

  1. Non-ad-hoc decision rule for the Dempster-Shafer method of evidential reasoning

    NASA Astrophysics Data System (ADS)

    Cheaito, Ali; Lecours, Michael; Bosse, Eloi

    1998-03-01

    This paper is concerned with the fusion of identity information through the use of statistical analysis rooted in Dempster-Shafer theory of evidence to provide automatic identification aboard a platform. An identity information process for a baseline Multi-Source Data Fusion (MSDF) system is defined. The MSDF system is applied to information sources which include a number of radars, IFF systems, an ESM system, and a remote track source. We use a comprehensive Platform Data Base (PDB) containing all the possible identity values that the potential target may take, and we use the fuzzy logic strategies which enable the fusion of subjective attribute information from sensor and the PDB to make the derivation of target identity more quickly, more precisely, and with statistically quantifiable measures of confidence. The conventional Dempster-Shafer lacks a formal basis upon which decision can be made in the face of ambiguity. We define a non-ad hoc decision rule based on the expected utility interval for pruning the `unessential' propositions which would otherwise overload the real-time data fusion systems. An example has been selected to demonstrate the implementation of our modified Dempster-Shafer method of evidential reasoning.

  2. An Efficient and QoS Supported Multichannel MAC Protocol for Vehicular Ad Hoc Networks

    PubMed Central

    Tan, Guozhen; Yu, Chao

    2017-01-01

    Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety (transport efficiency and infotainment) applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. Different types of applications require different levels Quality-of-Service (QoS) support. Recently, transport efficiency and infotainment applications (e.g., electronic map download and Internet access) have received more and more attention, and this kind of applications is expected to become a big market driver in a near future. In this paper, we propose an Efficient and QoS supported Multichannel Medium Access Control (EQM-MAC) protocol for VANETs in a highway environment. The EQM-MAC protocol utilizes the service channel resources for non-safety message transmissions during the whole synchronization interval, and it dynamically adjusts minimum contention window size for different non-safety services according to the traffic conditions. Theoretical model analysis and extensive simulation results show that the EQM-MAC protocol can support QoS services, while ensuring the high saturation throughput and low transmission delay for non-safety applications. PMID:28991217

  3. Data Delivery Method Based on Neighbor Nodes' Information in a Mobile Ad Hoc Network

    PubMed Central

    Hayashi, Takuma; Taenaka, Yuzo; Okuda, Takeshi; Yamaguchi, Suguru

    2014-01-01

    This paper proposes a data delivery method based on neighbor nodes' information to achieve reliable communication in a mobile ad hoc network (MANET). In a MANET, it is difficult to deliver data reliably due to instabilities in network topology and wireless network condition which result from node movement. To overcome such unstable communication, opportunistic routing and network coding schemes have lately attracted considerable attention. Although an existing method that employs such schemes, MAC-independent opportunistic routing and encoding (MORE), Chachulski et al. (2007), improves the efficiency of data delivery in an unstable wireless mesh network, it does not address node movement. To efficiently deliver data in a MANET, the method proposed in this paper thus first employs the same opportunistic routing and network coding used in MORE and also uses the location information and transmission probabilities of neighbor nodes to adapt to changeable network topology and wireless network condition. The simulation experiments showed that the proposed method can achieve efficient data delivery with low network load when the movement speed is relatively slow. PMID:24672371

  4. Data delivery method based on neighbor nodes' information in a mobile ad hoc network.

    PubMed

    Kashihara, Shigeru; Hayashi, Takuma; Taenaka, Yuzo; Okuda, Takeshi; Yamaguchi, Suguru

    2014-01-01

    This paper proposes a data delivery method based on neighbor nodes' information to achieve reliable communication in a mobile ad hoc network (MANET). In a MANET, it is difficult to deliver data reliably due to instabilities in network topology and wireless network condition which result from node movement. To overcome such unstable communication, opportunistic routing and network coding schemes have lately attracted considerable attention. Although an existing method that employs such schemes, MAC-independent opportunistic routing and encoding (MORE), Chachulski et al. (2007), improves the efficiency of data delivery in an unstable wireless mesh network, it does not address node movement. To efficiently deliver data in a MANET, the method proposed in this paper thus first employs the same opportunistic routing and network coding used in MORE and also uses the location information and transmission probabilities of neighbor nodes to adapt to changeable network topology and wireless network condition. The simulation experiments showed that the proposed method can achieve efficient data delivery with low network load when the movement speed is relatively slow.

  5. PCPA: A Practical Certificateless Conditional Privacy Preserving Authentication Scheme for Vehicular Ad Hoc Networks

    PubMed Central

    2018-01-01

    Vehicle ad hoc networks (VANETs) is a promising network scenario for greatly improving traffic efficiency and safety, in which smart vehicles can communicate with other vehicles or roadside units. For the availability of VANETs, it is very important to deal with the security and privacy problems for VANETs. In this paper, based on certificateless cryptography and elliptic curve cryptography, we present a certificateless signature with message recovery (CLS-MR), which we believe are of independent interest. Then, a practical certificateless conditional privacy preserving authentication (PCPA) scheme is proposed by incorporating the proposed CLS-MR scheme. Furthermore, the security analysis shows that PCPA satisfies all security and privacy requirements. The evaluation results indicate that PCPA achieves low computation and communication costs because there is no need to use the bilinear pairing and map-to-point hash operations. Moreover, extensive simulations show that PCPA is feasible and achieves prominent performances in terms of message delay and message loss ratio, and thus is more suitable for the deployment and adoption of VANETs. PMID:29762511

  6. Optimal JPWL Forward Error Correction Rate Allocation for Robust JPEG 2000 Images and Video Streaming over Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Agueh, Max; Diouris, Jean-François; Diop, Magaye; Devaux, François-Olivier; De Vleeschouwer, Christophe; Macq, Benoit

    2008-12-01

    Based on the analysis of real mobile ad hoc network (MANET) traces, we derive in this paper an optimal wireless JPEG 2000 compliant forward error correction (FEC) rate allocation scheme for a robust streaming of images and videos over MANET. The packet-based proposed scheme has a low complexity and is compliant to JPWL, the 11th part of the JPEG 2000 standard. The effectiveness of the proposed method is evaluated using a wireless Motion JPEG 2000 client/server application; and the ability of the optimal scheme to guarantee quality of service (QoS) to wireless clients is demonstrated.

  7. Report of the APS Ad-Hoc Committee on LGBT Issues - Presentation of Findings and Recommendations

    NASA Astrophysics Data System (ADS)

    Falk, Michael

    In 2014 the Executive Officer of the American Physical Society (APS), Kate Kirby, created an Ad-Hoc Committee on LGBT Issues (C-LGBT) charged with reporting on the obstacles to inclusion of LGBT physicists, a term which for the purpose of this report refers to persons who self-identify as lesbian, gay, bisexual, transgender, queer, questioning, intersex, or asexual, as well as other sexual and gender minorities. The full charge was as follows: ``The committee will advise the APS on the current status of LGBT issues in physics, provide recommendations for greater inclusion, and engage physicists in laying the foundation for a more inclusive physics community. ?More specifically, the committee will investigate LGBT representation in physics, assess the educational and professional climate in physics, recommend changes in policies and practices that impact LGBT physicists, and address other issues that affect inclusion.'' We will present the findings and recommendations of the C-LGBT final report, and a panel discussion will be held following the presentation to discuss the future of APS efforts toward LGBT inclusion in physics.

  8. Report of the APS Ad-Hoc Committee on LGBT Issues - Presentation of Findings and Recommendations

    NASA Astrophysics Data System (ADS)

    Long, Elena

    2016-03-01

    In 2014 the Executive Officer of the American Physical Society (APS), Kate Kirby, created an Ad-Hoc Committee on LGBT Issues (C-LGBT) charged with reporting on the obstacles to inclusion of LGBT physicists, a term which for the purpose of this report refers to persons who self-identify as lesbian, gay, bisexual, transgender, queer, questioning, intersex, or asexual, as well as other sexual and gender minorities. The full charge was as follows: ``The committee will advise the APS on the current status of LGBT issues in physics, provide recommendations for greater inclusion, and engage physicists in laying the foundation for a more inclusive physics community? More specifically, the committee will investigate LGBT representation in physics, assess the educational and professional climate in physics, recommend changes in policies and practices that impact LGBT physicists, and address other issues that affect inclusion.'' We will present the findings and recommendations of the C-LGBT final report, and a panel discussion will be held following the presentation to discuss the future of APS efforts toward LGBT inclusion in physics.

  9. Energy Efficient Link Aware Routing with Power Control in Wireless Ad Hoc Networks.

    PubMed

    Katiravan, Jeevaa; Sylvia, D; Rao, D Srinivasa

    2015-01-01

    In wireless ad hoc networks, the traditional routing protocols make the route selection based on minimum distance between the nodes and the minimum number of hop counts. Most of the routing decisions do not consider the condition of the network such as link quality and residual energy of the nodes. Also, when a link failure occurs, a route discovery mechanism is initiated which incurs high routing overhead. If the broadcast nature and the spatial diversity of the wireless communication are utilized efficiently it becomes possible to achieve improvement in the performance of the wireless networks. In contrast to the traditional routing scheme which makes use of a predetermined route for packet transmission, such an opportunistic routing scheme defines a predefined forwarding candidate list formed by using single network metrics. In this paper, a protocol is proposed which uses multiple metrics such as residual energy and link quality for route selection and also includes a monitoring mechanism which initiates a route discovery for a poor link, thereby reducing the overhead involved and improving the throughput of the network while maintaining network connectivity. Power control is also implemented not only to save energy but also to improve the network performance. Using simulations, we show the performance improvement attained in the network in terms of packet delivery ratio, routing overhead, and residual energy of the network.

  10. Integration of Body Sensor Networks and Vehicular Ad-hoc Networks for Traffic Safety.

    PubMed

    Reyes-Muñoz, Angelica; Domingo, Mari Carmen; López-Trinidad, Marco Antonio; Delgado, José Luis

    2016-01-15

    The emergence of Body Sensor Networks (BSNs) constitutes a new and fast growing trend for the development of daily routine applications. However, in the case of heterogeneous BSNs integration with Vehicular ad hoc Networks (VANETs) a large number of difficulties remain, that must be solved, especially when talking about the detection of human state factors that impair the driving of motor vehicles. The main contributions of this investigation are principally three: (1) an exhaustive review of the current mechanisms to detect four basic physiological behavior states (drowsy, drunk, driving under emotional state disorders and distracted driving) that may cause traffic accidents is presented; (2) A middleware architecture is proposed. This architecture can communicate with the car dashboard, emergency services, vehicles belonging to the VANET and road or street facilities. This architecture seeks on the one hand to improve the car driving experience of the driver and on the other hand to extend security mechanisms for the surrounding individuals; and (3) as a proof of concept, an Android real-time attention low level detection application that runs in a next-generation smartphone is developed. The application features mechanisms that allow one to measure the degree of attention of a driver on the base of her/his EEG signals, establish wireless communication links via various standard wireless means, GPRS, Bluetooth and WiFi and issue alarms of critical low driver attention levels.

  11. Energy Efficient Link Aware Routing with Power Control in Wireless Ad Hoc Networks

    PubMed Central

    Katiravan, Jeevaa; Sylvia, D.; Rao, D. Srinivasa

    2015-01-01

    In wireless ad hoc networks, the traditional routing protocols make the route selection based on minimum distance between the nodes and the minimum number of hop counts. Most of the routing decisions do not consider the condition of the network such as link quality and residual energy of the nodes. Also, when a link failure occurs, a route discovery mechanism is initiated which incurs high routing overhead. If the broadcast nature and the spatial diversity of the wireless communication are utilized efficiently it becomes possible to achieve improvement in the performance of the wireless networks. In contrast to the traditional routing scheme which makes use of a predetermined route for packet transmission, such an opportunistic routing scheme defines a predefined forwarding candidate list formed by using single network metrics. In this paper, a protocol is proposed which uses multiple metrics such as residual energy and link quality for route selection and also includes a monitoring mechanism which initiates a route discovery for a poor link, thereby reducing the overhead involved and improving the throughput of the network while maintaining network connectivity. Power control is also implemented not only to save energy but also to improve the network performance. Using simulations, we show the performance improvement attained in the network in terms of packet delivery ratio, routing overhead, and residual energy of the network. PMID:26167529

  12. Dynamic Agent Classification and Tracking Using an Ad Hoc Mobile Acoustic Sensor Network

    NASA Astrophysics Data System (ADS)

    Friedlander, David; Griffin, Christopher; Jacobson, Noah; Phoha, Shashi; Brooks, Richard R.

    2003-12-01

    Autonomous networks of sensor platforms can be designed to interact in dynamic and noisy environments to determine the occurrence of specified transient events that define the dynamic process of interest. For example, a sensor network may be used for battlefield surveillance with the purpose of detecting, identifying, and tracking enemy activity. When the number of nodes is large, human oversight and control of low-level operations is not feasible. Coordination and self-organization of multiple autonomous nodes is necessary to maintain connectivity and sensor coverage and to combine information for better understanding the dynamics of the environment. Resource conservation requires adaptive clustering in the vicinity of the event. This paper presents methods for dynamic distributed signal processing using an ad hoc mobile network of microsensors to detect, identify, and track targets in noisy environments. They seamlessly integrate data from fixed and mobile platforms and dynamically organize platforms into clusters to process local data along the trajectory of the targets. Local analysis of sensor data is used to determine a set of target attribute values and classify the target. Sensor data from a field test in the Marine base at Twentynine Palms, Calif, was analyzed using the techniques described in this paper. The results were compared to "ground truth" data obtained from GPS receivers on the vehicles.

  13. International survey of vestibular rehabilitation therapists by the Barany Society Ad Hoc Committee on Vestibular Rehabilitation Therapy.

    PubMed

    Cohen, Helen S; Gottshall, Kim R; Graziano, Mariella; Malmstrom, Eva-Maj; Sharpe, Margaret H

    2009-01-01

    The goal of this study was to determine how occupational and physical therapists learn about vestibular rehabilitation therapy, their educational backgrounds, referral patterns, and their ideas about entry-level and advanced continuing education in vestibular rehabilitation therapy. The Barany Society Ad Hoc Committee for Vestibular Rehabilitation Therapy invited therapists around the world to complete an E-mail survey. Participants were either known to committee members or other Barany Society members, known to other participants, identified from their self-listings on the Internet, or volunteered after reading notices published in publications read by therapists. Responses were received from 133 therapists in 19 countries. They had a range of educational backgrounds, practice settings, and referral patterns. Few respondents had had any training about vestibular rehabilitation during their professional entry-level education. Most respondents learned about vestibular rehabilitation from continuing education courses, interactions with their colleagues, and reading. All of them endorsed the concept of developing standards and educating therapists about vestibular anatomy and physiology, vestibular diagnostic testing, vestibular disorders and current intervention strategies. Therefore, the Committee recommends the development of international standards for education and practice in vestibular rehabilitation therapy.

  14. An adaptive neural swarm approach for intrusion defense in ad hoc networks

    NASA Astrophysics Data System (ADS)

    Cannady, James

    2011-06-01

    Wireless sensor networks (WSN) and mobile ad hoc networks (MANET) are being increasingly deployed in critical applications due to the flexibility and extensibility of the technology. While these networks possess numerous advantages over traditional wireless systems in dynamic environments they are still vulnerable to many of the same types of host-based and distributed attacks common to those systems. Unfortunately, the limited power and bandwidth available in WSNs and MANETs, combined with the dynamic connectivity that is a defining characteristic of the technology, makes it extremely difficult to utilize traditional intrusion detection techniques. This paper describes an approach to accurately and efficiently detect potentially damaging activity in WSNs and MANETs. It enables the network as a whole to recognize attacks, anomalies, and potential vulnerabilities in a distributive manner that reflects the autonomic processes of biological systems. Each component of the network recognizes activity in its local environment and then contributes to the overall situational awareness of the entire system. The approach utilizes agent-based swarm intelligence to adaptively identify potential data sources on each node and on adjacent nodes throughout the network. The swarm agents then self-organize into modular neural networks that utilize a reinforcement learning algorithm to identify relevant behavior patterns in the data without supervision. Once the modular neural networks have established interconnectivity both locally and with neighboring nodes the analysis of events within the network can be conducted collectively in real-time. The approach has been shown to be extremely effective in identifying distributed network attacks.

  15. Enhancing the Selection of Backoff Interval Using Fuzzy Logic over Wireless Ad Hoc Networks

    PubMed Central

    Ranganathan, Radha; Kannan, Kathiravan

    2015-01-01

    IEEE 802.11 is the de facto standard for medium access over wireless ad hoc network. The collision avoidance mechanism (i.e., random binary exponential backoff—BEB) of IEEE 802.11 DCF (distributed coordination function) is inefficient and unfair especially under heavy load. In the literature, many algorithms have been proposed to tune the contention window (CW) size. However, these algorithms make every node select its backoff interval between [0, CW] in a random and uniform manner. This randomness is incorporated to avoid collisions among the nodes. But this random backoff interval can change the optimal order and frequency of channel access among competing nodes which results in unfairness and increased delay. In this paper, we propose an algorithm that schedules the medium access in a fair and effective manner. This algorithm enhances IEEE 802.11 DCF with additional level of contention resolution that prioritizes the contending nodes according to its queue length and waiting time. Each node computes its unique backoff interval using fuzzy logic based on the input parameters collected from contending nodes through overhearing. We evaluate our algorithm against IEEE 802.11, GDCF (gentle distributed coordination function) protocols using ns-2.35 simulator and show that our algorithm achieves good performance. PMID:25879066

  16. SVANET: A smart vehicular ad hoc network for efficient data transmission with wireless sensors.

    PubMed

    Sahoo, Prasan Kumar; Chiang, Ming-Jer; Wu, Shih-Lin

    2014-11-25

    Wireless sensors can sense any event, such as accidents, as well as icy roads, and can forward the rescue/warning messages through intermediate vehicles for any necessary help. In this paper, we propose a smart vehicular ad hoc network (SVANET) architecture that uses wireless sensors to detect events and vehicles to transmit the safety and non-safety messages efficiently by using different service channels and one control channel with different priorities. We have developed a data transmission protocol for the vehicles in the highway, in which data can be forwarded with the help of vehicles if they are connected with each other or data can be forwarded with the help of nearby wireless sensors. Our data transmission protocol is designed to increase the driving safety, to prevent accidents and to utilize channels efficiently by adjusting the control and service channel time intervals dynamically. Besides, our protocol can transmit information to vehicles in advance, so that drivers can decide an alternate route in case of traffic congestion. For various data sharing, we design a method that can select a few leader nodes among vehicles running along a highway to broadcast data efficiently. Simulation results show that our protocol can outperform the existing standard in terms of the end to end packet delivery ratio and latency.

  17. Frame Transmission Efficiency-Based Cross-Layer Congestion Notification Scheme in Wireless Ad Hoc Networks.

    PubMed

    He, Huaguang; Li, Taoshen; Feng, Luting; Ye, Jin

    2017-07-15

    Different from the traditional wired network, the fundamental cause of transmission congestion in wireless ad hoc networks is medium contention. How to utilize the congestion state from the MAC (Media Access Control) layer to adjust the transmission rate is core work for transport protocol design. However, recent works have shown that the existing cross-layer congestion detection solutions are too complex to be deployed or not able to characterize the congestion accurately. We first propose a new congestion metric called frame transmission efficiency (i.e., the ratio of successful transmission delay to the frame service delay), which describes the medium contention in a fast and accurate manner. We further present the design and implementation of RECN (ECN and the ratio of successful transmission delay to the frame service delay in the MAC layer, namely, the frame transmission efficiency), a general supporting scheme that adjusts the transport sending rate through a standard ECN (Explicit Congestion Notification) signaling method. Our method can be deployed on commodity switches with small firmware updates, while making no modification on end hosts. We integrate RECN transparently (i.e., without modification) with TCP on NS2 simulation. The experimental results show that RECN remarkably improves network goodput across multiple concurrent TCP flows.

  18. Direct trust-based security scheme for RREQ flooding attack in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Dutta, Kamlesh

    2017-06-01

    The routing algorithms in MANETs exhibit distributed and cooperative behaviour which makes them easy target for denial of service (DoS) attacks. RREQ flooding attack is a flooding-type DoS attack in context to Ad hoc On Demand Distance Vector (AODV) routing protocol, where the attacker broadcasts massive amount of bogus Route Request (RREQ) packets to set up the route with the non-existent or existent destination in the network. This paper presents direct trust-based security scheme to detect and mitigate the impact of RREQ flooding attack on the network, in which, every node evaluates the trust degree value of its neighbours through analysing the frequency of RREQ packets originated by them over a short period of time. Taking the node's trust degree value as the input, the proposed scheme is smoothly extended for suppressing the surplus RREQ and bogus RREQ flooding packets at one-hop neighbours during the route discovery process. This scheme distinguishes itself from existing techniques by not directly blocking the service of a normal node due to increased amount of RREQ packets in some unusual conditions. The results obtained throughout the simulation experiments clearly show the feasibility and effectiveness of the proposed defensive scheme.

  19. Secure and Fair Cluster Head Selection Protocol for Enhancing Security in Mobile Ad Hoc Networks

    PubMed Central

    Paramasivan, B.; Kaliappan, M.

    2014-01-01

    Mobile ad hoc networks (MANETs) are wireless networks consisting of number of autonomous mobile devices temporarily interconnected into a network by wireless media. MANETs become one of the most prevalent areas of research in the recent years. Resource limitations, energy efficiency, scalability, and security are the great challenging issues in MANETs. Due to its deployment nature, MANETs are more vulnerable to malicious attack. The secure routing protocols perform very basic security related functions which are not sufficient to protect the network. In this paper, a secure and fair cluster head selection protocol (SFCP) is proposed which integrates security factors into the clustering approach for achieving attacker identification and classification. Byzantine agreement based cooperative technique is used for attacker identification and classification to make the network more attack resistant. SFCP used to solve this issue by making the nodes that are totally surrounded by malicious neighbors adjust dynamically their belief and disbelief thresholds. The proposed protocol selects the secure and energy efficient cluster head which acts as a local detector without imposing overhead to the clustering performance. SFCP is simulated in network simulator 2 and compared with two protocols including AODV and CBRP. PMID:25143986

  20. VehiHealth: An Emergency Routing Protocol for Vehicular Ad Hoc Network to Support Healthcare System.

    PubMed

    Bhoi, S K; Khilar, P M

    2016-03-01

    Survival of a patient depends on effective data communication in healthcare system. In this paper, an emergency routing protocol for Vehicular Ad hoc Network (VANET) is proposed to quickly forward the current patient status information from the ambulance to the hospital to provide pre-medical treatment. As the ambulance takes time to reach the hospital, ambulance doctor can provide sudden treatment to the patient in emergency by sending patient status information to the hospital through the vehicles using vehicular communication. Secondly, the experienced doctors respond to the information by quickly sending a treatment information to the ambulance. In this protocol, data is forwarded through that path which has less link breakage problem between the vehicles. This is done by calculating an intersection value I v a l u e for the neighboring intersections by using the current traffic information. Then the data is forwarded through that intersection which has minimum I v a l u e . Simulation results show VehiHealth performs better than P-GEDIR, GyTAR, A-STAR and GSR routing protocols in terms of average end-to-end delay, number of link breakage, path length, and average response time.

  1. Secure and fair cluster head selection protocol for enhancing security in mobile ad hoc networks.

    PubMed

    Paramasivan, B; Kaliappan, M

    2014-01-01

    Mobile ad hoc networks (MANETs) are wireless networks consisting of number of autonomous mobile devices temporarily interconnected into a network by wireless media. MANETs become one of the most prevalent areas of research in the recent years. Resource limitations, energy efficiency, scalability, and security are the great challenging issues in MANETs. Due to its deployment nature, MANETs are more vulnerable to malicious attack. The secure routing protocols perform very basic security related functions which are not sufficient to protect the network. In this paper, a secure and fair cluster head selection protocol (SFCP) is proposed which integrates security factors into the clustering approach for achieving attacker identification and classification. Byzantine agreement based cooperative technique is used for attacker identification and classification to make the network more attack resistant. SFCP used to solve this issue by making the nodes that are totally surrounded by malicious neighbors adjust dynamically their belief and disbelief thresholds. The proposed protocol selects the secure and energy efficient cluster head which acts as a local detector without imposing overhead to the clustering performance. SFCP is simulated in network simulator 2 and compared with two protocols including AODV and CBRP.

  2. Integration of Body Sensor Networks and Vehicular Ad-hoc Networks for Traffic Safety

    PubMed Central

    Reyes-Muñoz, Angelica; Domingo, Mari Carmen; López-Trinidad, Marco Antonio; Delgado, José Luis

    2016-01-01

    The emergence of Body Sensor Networks (BSNs) constitutes a new and fast growing trend for the development of daily routine applications. However, in the case of heterogeneous BSNs integration with Vehicular ad hoc Networks (VANETs) a large number of difficulties remain, that must be solved, especially when talking about the detection of human state factors that impair the driving of motor vehicles. The main contributions of this investigation are principally three: (1) an exhaustive review of the current mechanisms to detect four basic physiological behavior states (drowsy, drunk, driving under emotional state disorders and distracted driving) that may cause traffic accidents is presented; (2) A middleware architecture is proposed. This architecture can communicate with the car dashboard, emergency services, vehicles belonging to the VANET and road or street facilities. This architecture seeks on the one hand to improve the car driving experience of the driver and on the other hand to extend security mechanisms for the surrounding individuals; and (3) as a proof of concept, an Android real-time attention low level detection application that runs in a next-generation smartphone is developed. The application features mechanisms that allow one to measure the degree of attention of a driver on the base of her/his EEG signals, establish wireless communication links via various standard wireless means, GPRS, Bluetooth and WiFi and issue alarms of critical low driver attention levels. PMID:26784204

  3. Ad Hoc Influenza Vaccination During Years of Significant Antigenic Drift in a Tropical City With 2 Seasonal Peaks

    PubMed Central

    Wong, Martin C.S.; Nelson, E. Anthony S.; Leung, Czarina; Lee, Nelson; Chan, Martin C.W.; Choi, Kin Wing; Rainer, Timothy H.; Cheng, Frankie W.T.; Wong, Samuel Y.S.; Lai, Christopher K.C.; Lam, Bosco; Cheung, Tak Hong; Leung, Ting Fan; Chan, Paul K.S.

    2016-01-01

    Abstract We evaluated the acceptability of an additional ad hoc influenza vaccination among the health care professionals following seasons with significant antigenic drift. Self-administered, anonymous surveys were performed by hard copy questionnaires in public hospitals, and by an on-line platform available to all healthcare professionals, from April 1st to May 31st, 2015. A total of 1290 healthcare professionals completed the questionnaires, including doctors, nurses, and allied health professionals working in both the public and private systems. Only 31.8% of participating respondents expressed an intention to receive the additional vaccine, despite that the majority of them agreed or strongly agreed that it would bring benefit to the community (88.9%), save lives (86.7%), reduce medical expenses (76.3%), satisfy public expectation (82.8%), and increase awareness of vaccination (86.1%). However, a significant proportion expressed concern that the vaccine could disturb the normal immunization schedule (45.5%); felt uncertain what to do in the next vaccination round (66.0%); perceived that the summer peak might not occur (48.2%); and believed that the summer peak might not be of the same virus (83.5%). Furthermore, 27.8% of all respondents expected that the additional vaccination could weaken the efficacy of previous vaccinations; 51.3% was concerned about side effects; and 61.3% estimated that there would be a low uptake rate. If the supply of vaccine was limited, higher priority groups were considered to include the elderly aged ≥65 years with chronic medical conditions (89.2%), the elderly living in residential care homes (87.4%), and long-stay residents of institutions for the disabled (80.7%). The strongest factors associated with accepting the additional vaccine included immunization with influenza vaccines in the past 3 years, higher perceived risk of contracting influenza, and higher perceived severity of the disease impact. The acceptability to an

  4. Ad hoc posterior tibial vessels perforator propeller flaps for the reconstruction of lower third leg soft- tissue defects.

    PubMed

    Balakrishnan, Thalaivirithan Margabandu; Ramkumar, Jayagosh; Jaganmohan, Janardhanan

    2017-01-01

    Lower third leg soft tissue defects with anatomical and pathological constraints are posing formidable challenges to reconstructive surgeon. This retrospective study was conducted to assess the effectiveness of ad hoc posterior tibial vessels perforator-propeller flaps for the reconstruction of small and medium sized soft tissue defects in the lower third leg. 22 patients (16 were males and 6 were females) were involved in this study between period of January 2012 and December 2016.We followed the protocol of initial non delineating exploratory incision made to find out single best perforator in all patients. All the defects in leg reconstructed with adhoc posterior tibial vessel propeller flaps. All 22 flaps survived well. All in an average of 13 months follow up period, had pain free walking, with minimal scarring and acceptable aesthesis at the reconstruction sites with no need for any secondary procedure. With inability of preoperatively dopplering the perforators in the lower third leg region, the exploratory posterior nondelineating incision was used in all cases to secure the single best perforator for the propeller flaps. Thus adhoc posterior tibial vessel propeller flaps are dependable, easily adoptable for the reconstruction of soft tissue defects of the lower third leg region.

  5. Ad hoc posterior tibial vessels perforator propeller flaps for the reconstruction of lower third leg soft- tissue defects

    PubMed Central

    Balakrishnan, Thalaivirithan Margabandu; Ramkumar, Jayagosh; Jaganmohan, Janardhanan

    2017-01-01

    Introduction: Lower third leg soft tissue defects with anatomical and pathological constraints are posing formidable challenges to reconstructive surgeon. Aim: This retrospective study was conducted to assess the effectiveness of ad hoc posterior tibial vessels perforator-propeller flaps for the reconstruction of small and medium sized soft tissue defects in the lower third leg. Patients and Methods: 22 patients (16 were males and 6 were females) were involved in this study between period of January 2012 and December 2016.We followed the protocol of initial non delineating exploratory incision made to find out single best perforator in all patients. All the defects in leg reconstructed with adhoc posterior tibial vessel propeller flaps. Results: All 22 flaps survived well. All in an average of 13 months follow up period, had pain free walking, with minimal scarring and acceptable aesthesis at the reconstruction sites with no need for any secondary procedure. Conclusion: With inability of preoperatively dopplering the perforators in the lower third leg region, the exploratory posterior nondelineating incision was used in all cases to secure the single best perforator for the propeller flaps. Thus adhoc posterior tibial vessel propeller flaps are dependable, easily adoptable for the reconstruction of soft tissue defects of the lower third leg region. PMID:29618863

  6. Neuroprotection as initial therapy in acute stroke. Third Report of an Ad Hoc Consensus Group Meeting. The European Ad Hoc Consensus Group.

    PubMed

    1998-01-01

    Although a considerable body of scientific data is now available on neuroprotection in acute ischaemic stroke, this field is not yet established in clinical practice. At its third meeting, the European Ad Hoc Consensus Group considered the potential for neuroprotection in acute stroke and the practical problems attendant on the existence of a very limited therapeutic window before irreversible brain damage occurs, and came to the following conclusions. NEUROPROTECTANTS IN CLINICAL DEVELOPMENT: Convincing clinical evidence for an efficacious neuroprotective treatment in acute stroke is still required. Caution should be exercised in interpreting and extrapolating experimental results to stroke patients, who are a very heterogeneous group. The limitations of the time windows and the outcome measures chosen in trials of acute stroke therapy have an important influence on the results. The overall distribution of functional outcomes provides more statistical information than the proportion above a threshold outcome value. Neurological outcome should also be assessed. Neuroprotectants should not be tested clinically in phase II or phase III trials in a time window that exceeds those determined in experimental studies. The harmful effects of a drug in humans may override its neuroprotective potential determined in animals. Agents that act at several different levels in the ischaemic cascade may be more effective than those with a single mechanism of action. CURRENT IN-HOSPITAL MANAGEMENT OF ACUTE STROKE: The four major physiological variables that must be monitored and managed are blood pressure, arterial blood gas levels, body temperature, and glycaemia. The effects of controlling these physiological variables have not been studied in prospective trials, though they may all contribute to the outcome of acute ischaemic stroke and affect the duration of the therapeutic window. Optimal physiological parameters are inherently neuroprotective. Trials of new agents for the

  7. Concurrent Transmission Based on Channel Quality in Ad Hoc Networks: A Game Theoretic Approach

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Gao, Xinbo; Li, Xiaoji; Pei, Qingqi

    In this paper, a decentralized concurrent transmission strategy in shared channel in Ad Hoc networks is proposed based on game theory. Firstly, a static concurrent transmissions game is used to determine the candidates for transmitting by channel quality threshold and to maximize the overall throughput with consideration of channel quality variation. To achieve NES (Nash Equilibrium Solution), the selfish behaviors of node to attempt to improve the channel gain unilaterally are evaluated. Therefore, this game allows each node to be distributed and to decide whether to transmit concurrently with others or not depending on NES. Secondly, as there are always some nodes with lower channel gain than NES, which are defined as hunger nodes in this paper, a hunger suppression scheme is proposed by adjusting the price function with interferences reservation and forward relay, to fairly give hunger nodes transmission opportunities. Finally, inspired by stock trading, a dynamic concurrent transmission threshold determination scheme is implemented to make the static game practical. Numerical results show that the proposed scheme is feasible to increase concurrent transmission opportunities for active nodes, and at the same time, the number of hunger nodes is greatly reduced with the least increase of threshold by interferences reservation. Also, the good performance on network goodput of the proposed model can be seen from the results.

  8. SVANET: A Smart Vehicular Ad Hoc Network for Efficient Data Transmission with Wireless Sensors

    PubMed Central

    Sahoo, Prasan Kumar; Chiang, Ming-Jer; Wu, Shih-Lin

    2014-01-01

    Wireless sensors can sense any event, such as accidents, as well as icy roads, and can forward the rescue/warning messages through intermediate vehicles for any necessary help. In this paper, we propose a smart vehicular ad hoc network (SVANET) architecture that uses wireless sensors to detect events and vehicles to transmit the safety and non-safety messages efficiently by using different service channels and one control channel with different priorities. We have developed a data transmission protocol for the vehicles in the highway, in which data can be forwarded with the help of vehicles if they are connected with each other or data can be forwarded with the help of nearby wireless sensors. Our data transmission protocol is designed to increase the driving safety, to prevent accidents and to utilize channels efficiently by adjusting the control and service channel time intervals dynamically. Besides, our protocol can transmit information to vehicles in advance, so that drivers can decide an alternate route in case of traffic congestion. For various data sharing, we design a method that can select a few leader nodes among vehicles running along a highway to broadcast data efficiently. Simulation results show that our protocol can outperform the existing standard in terms of the end to end packet delivery ratio and latency. PMID:25429409

  9. Performance evaluation of reactive and proactive routing protocol in IEEE 802.11 ad hoc network

    NASA Astrophysics Data System (ADS)

    Hamma, Salima; Cizeron, Eddy; Issaka, Hafiz; Guédon, Jean-Pierre

    2006-10-01

    Wireless technology based on the IEEE 802.11 standard is widely deployed. This technology is used to support multiple types of communication services (data, voice, image) with different QoS requirements. MANET (Mobile Adhoc NETwork) does not require a fixed infrastructure. Mobile nodes communicate through multihop paths. The wireless communication medium has variable and unpredictable characteristics. Furthermore, node mobility creates a continuously changing communication topology in which paths break and new one form dynamically. The routing table of each router in an adhoc network must be kept up-to-date. MANET uses Distance Vector or Link State algorithms which insure that the route to every host is always known. However, this approach must take into account the adhoc networks specific characteristics: dynamic topologies, limited bandwidth, energy constraints, limited physical security, ... Two main routing protocols categories are studied in this paper: proactive protocols (e.g. Optimised Link State Routing - OLSR) and reactive protocols (e.g. Ad hoc On Demand Distance Vector - AODV, Dynamic Source Routing - DSR). The proactive protocols are based on periodic exchanges that update the routing tables to all possible destinations, even if no traffic goes through. The reactive protocols are based on on-demand route discoveries that update routing tables only for the destination that has traffic going through. The present paper focuses on study and performance evaluation of these categories using NS2 simulations. We have considered qualitative and quantitative criteria. The first one concerns distributed operation, loop-freedom, security, sleep period operation. The second are used to assess performance of different routing protocols presented in this paper. We can list end-to-end data delay, jitter, packet delivery ratio, routing load, activity distribution. Comparative study will be presented with number of networking context consideration and the results show

  10. Standardization of Negative Controls in Diagnostic Immunohistochemistry: Recommendations From the International Ad Hoc Expert Panel

    PubMed Central

    Torlakovic, Emina E.; Francis, Glenn; Garratt, John; Gilks, Blake; Hyjek, Elizabeth; Ibrahim, Merdol; Miller, Rodney; Nielsen, Søren; Petcu, Eugen B.; Swanson, Paul E.; Taylor, Clive R.; Vyberg, Mogens

    2014-01-01

    Standardization of controls, both positive and negative controls, is needed for diagnostic immunohistochemistry (dIHC). The use of IHC-negative controls, irrespective of type, although well established, is not standardized. As such, the relevance and applicability of negative controls continues to challenge both pathologists and laboratory budgets. Despite the clear theoretical notion that appropriate controls serve to demonstrate the sensitivity and specificity of the dIHC test, it remains unclear which types of positive and negative controls are applicable and/or useful in day-to-day clinical practice. There is a perceived need to provide “best practice recommendations” for the use of negative controls. This perception is driven not only by logistics and cost issues, but also by increased pressure for accurate IHC testing, especially when IHC is performed for predictive markers, the number of which is rising as personalized medicine continues to develop. Herein, an international ad hoc expert panel reviews classification of negative controls relevant to clinical practice, proposes standard terminology for negative controls, considers the total evidence of IHC specificity that is available to pathologists, and develops a set of recommendations for the use of negative controls in dIHC based on “fit-for-use” principles. PMID:24714041

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  12. Exploring the Role of Ad Hoc Grassroots Organizations Providing Humanitarian Aid on Lesvos, Greece

    PubMed Central

    Kitching, George Tjensvoll; J. Haavik, Hanne; Tandstad, Birgit J.; Zaman, Muhammad; Darj, Elisabeth

    2016-01-01

    Introduction: Syrian refugees displaced into Turkey have attempted high-risk sea migrations to reach safer destinations in Europe, most often initially arriving on the Greek island of Lesvos. These refugees were often in need of basic humanitarian assistance that has been provided in part by a new category of ad hoc grassroots organizations (AHGOs). The aim of this study was to understand the internal and external operations of these AHGOs and their role on Lesvos. Methods: The experiences of AHGOs were investigated through a qualitative research design utilizing semi-structured interviews with organization leaders and spokespersons. AHGOs identified through media and social media sources as new Lesvos-specific organizations were purposively invited to complete an interview over phone, Skype or email. Data analysis of the transcribed interviews was performed by Systematic Text Condensation. Results: Forty-one organizations were contacted and 13 interviews were conducted. Most organizations were formed in autumn 2015 responding to the greater influx of refugees and migrants at that time and reported an absence of professional humanitarian agencies providing aid on Lesvos. Three categories emerged from the material. Features of organizations; Features of volunteers and; Evolution of AHGOs. The organizations perceived themselves capable of evaluating needs, mobilizing resources, funding and providing quick response. The volunteers came with limited humanitarian experience and from a wide variety of nationalities and professional backgrounds, and the organizations developed while on Lesvos. Discussion: Knowledge from our findings of AHGOs response to this complex disaster on Lesvos could be utilized in future catastrophes. We conclude that AHGOs may prove effective at providing humanitarian aid in a surge response when international non-governmental organizations are unable to respond quickly. In future complex disasters AHGOs should be recognized as new humanitarian

  13. Exploring the Role of Ad Hoc Grassroots Organizations Providing Humanitarian Aid on Lesvos, Greece.

    PubMed

    Kitching, George Tjensvoll; J Haavik, Hanne; Tandstad, Birgit J; Zaman, Muhammad; Darj, Elisabeth

    2016-11-17

    Syrian refugees displaced into Turkey have attempted high-risk sea migrations to reach safer destinations in Europe, most often initially arriving on the Greek island of Lesvos. These refugees were often in need of basic humanitarian assistance that has been provided in part by a new category of ad hoc grassroots organizations (AHGOs). The aim of this study was to understand the internal and external operations of these AHGOs and their role on Lesvos. The experiences of AHGOs were investigated through a qualitative research design utilizing semi-structured interviews with organization leaders and spokespersons. AHGOs identified through media and social media sources as new Lesvos-specific organizations were purposively invited to complete an interview over phone, Skype or email. Data analysis of the transcribed interviews was performed by Systematic Text Condensation. Forty-one organizations were contacted and 13 interviews were conducted. Most organizations were formed in autumn 2015 responding to the greater influx of refugees and migrants at that time and reported an absence of professional humanitarian agencies providing aid on Lesvos. Three categories emerged from the material. Features of organizations; Features of volunteers and; Evolution of AHGOs. The organizations perceived themselves capable of evaluating needs, mobilizing resources, funding and providing quick response. The volunteers came with limited humanitarian experience and from a wide variety of nationalities and professional backgrounds, and the organizations developed while on Lesvos. Knowledge from our findings of AHGOs response to this complex disaster on Lesvos could be utilized in future catastrophes. We conclude that AHGOs may prove effective at providing humanitarian aid in a surge response when international non-governmental organizations are unable to respond quickly. In future complex disasters AHGOs should be recognized as new humanitarian actors and conditions should be made

  14. Performance analysis of multi-radio routing protocol in cognitive radio ad hoc networks under different path failure rate

    NASA Astrophysics Data System (ADS)

    Che-Aron, Z.; Abdalla, A. H.; Abdullah, K.; Hassan, W. H.

    2013-12-01

    In recent years, Cognitive Radio (CR) technology has largely attracted significant studies and research. Cognitive Radio Ad Hoc Network (CRAHN) is an emerging self-organized, multi-hop, wireless network which allows unlicensed users to opportunistically access available licensed spectrum bands for data communication under an intelligent and cautious manner. However, in CRAHNs, a lot of failures can easily occur during data transmission caused by PU (Primary User) activity, topology change, node fault, or link degradation. In this paper, an attempt has been made to evaluate the performance of the Multi-Radio Link-Quality Source Routing (MR-LQSR) protocol in CRAHNs under different path failure rate. In the MR-LQSR protocol, the Weighted Cumulative Expected Transmission Time (WCETT) is used as the routing metric. The simulations are carried out using the NS-2 simulator. The protocol performance is evaluated with respect to performance metrics like average throughput, packet loss, average end-to-end delay and average jitter. From the simulation results, it is observed that the number of path failures depends on the PUs number and mobility rate of SUs (Secondary Users). Moreover, the protocol performance is greatly affected when the path failure rate is high, leading to major service outages.

  15. Performance Analysis of the IEEE 802.11p Multichannel MAC Protocol in Vehicular Ad Hoc Networks

    PubMed Central

    2017-01-01

    Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. The safety applications require timely and reliable transmissions, while the non-safety applications require efficient and high throughput. In the IEEE 1609.4 protocol, operating interval is divided into alternating Control Channel (CCH) interval and Service Channel (SCH) interval with an identical length. During the CCH interval, nodes transmit safety-related messages and control messages, and Enhanced Distributed Channel Access (EDCA) mechanism is employed to allow four Access Categories (ACs) within a station with different priorities according to their criticality for the vehicle’s safety. During the SCH interval, the non-safety massages are transmitted. An analytical model is proposed in this paper to evaluate performance, reliability and efficiency of the IEEE 802.11p and IEEE 1609.4 protocols. The proposed model improves the existing work by taking serval aspects and the character of multichannel switching into design consideration. Extensive performance evaluations based on analysis and simulation help to validate the accuracy of the proposed model and analyze the capabilities and limitations of the IEEE 802.11p and IEEE 1609.4 protocols, and enhancement suggestions are given. PMID:29231882

  16. Performance Analysis of the IEEE 802.11p Multichannel MAC Protocol in Vehicular Ad Hoc Networks.

    PubMed

    Song, Caixia

    2017-12-12

    Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. The safety applications require timely and reliable transmissions, while the non-safety applications require efficient and high throughput. In the IEEE 1609.4 protocol, operating interval is divided into alternating Control Channel (CCH) interval and Service Channel (SCH) interval with an identical length. During the CCH interval, nodes transmit safety-related messages and control messages, and Enhanced Distributed Channel Access (EDCA) mechanism is employed to allow four Access Categories (ACs) within a station with different priorities according to their criticality for the vehicle's safety. During the SCH interval, the non-safety massages are transmitted. An analytical model is proposed in this paper to evaluate performance, reliability and efficiency of the IEEE 802.11p and IEEE 1609.4 protocols. The proposed model improves the existing work by taking serval aspects and the character of multichannel switching into design consideration. Extensive performance evaluations based on analysis and simulation help to validate the accuracy of the proposed model and analyze the capabilities and limitations of the IEEE 802.11p and IEEE 1609.4 protocols, and enhancement suggestions are given.

  17. Ad-hoc and context-dependent adjustments of selective attention in conflict control: an ERP study with visual probes.

    PubMed

    Nigbur, R; Schneider, J; Sommer, W; Dimigen, O; Stürmer, B

    2015-02-15

    Cognitive conflict control in flanker tasks has often been described using the zoom-lens metaphor of selective attention. However, whether and how selective attention - in terms of suppression and enhancement - operates in this context has remained unclear. To examine the dynamic interplay of selective attention and cognitive control we used electrophysiological measures and presented task-irrelevant visual probe stimuli at foveal, parafoveal, and peripheral display positions. Target-flanker congruency varied either randomly from trial to trial (mixed-block) or block-wise (fixed-block) in order to induce reactive versus proactive control modes, respectively. Three EEG measures were used to capture ad-hoc adjustments within trials as well as effects of context-based predictions: the N1 component of the visual evoked potential (VEP) to probes, the VEP to targets, and the conflict-related midfrontal N2 component. Results from probe-VEPs indicate that enhanced processing of the foveal target rather than suppression of the peripheral flankers supports interference control. In incongruent mixed-block trials VEPs were larger to probes near the targets. In the fixed-blocks probe-VEPs were not modulated, but contrary to the mixed-block the preceding target-related VEP was affected by congruency. Results of the control-related N2 reveal largest amplitudes in the unpredictable context, which did not differentiate for stimulus and response incongruency. In contrast, in the predictable context, N2 amplitudes were reduced overall and differentiated between stimulus and response incongruency. Taken together these results imply that predictability alters interference control by a reconfiguration of stimulus processing. During unpredictable sequences participants adjust their attentional focus dynamically on a trial-by-trial basis as reflected in congruency-dependent probe-VEP-modulation. This reactive control mode also elicits larger N2 amplitudes. In contrast, when task demands

  18. Road Accident Prevention with Instant Emergency Warning Message Dissemination in Vehicular Ad-Hoc Network.

    PubMed

    Gokulakrishnan, P; Ganeshkumar, P

    2015-01-01

    A Road Accident Prevention (RAP) scheme based on Vehicular Backbone Network (VBN) structure is proposed in this paper for Vehicular Ad-hoc Network (VANET). The RAP scheme attempts to prevent vehicles from highway road traffic accidents and thereby reduces death and injury rates. Once the possibility of an emergency situation (i.e. an accident) is predicted in advance, instantly RAP initiates a highway road traffic accident prevention scheme. The RAP scheme constitutes the following activities: (i) the Road Side Unit (RSU) constructs a Prediction Report (PR) based on the status of the vehicles and traffic in the highway roads, (ii) the RSU generates an Emergency Warning Message (EWM) based on an abnormal PR, (iii) the RSU forms a VBN structure and (iv) the RSU disseminates the EWM to the vehicles that holds the high Risk Factor (RF) and travels in High Risk Zone (HRZ). These vehicles might reside either within the RSU's coverage area or outside RSU's coverage area (reached using VBN structure). The RAP scheme improves the performance of EWM dissemination in terms of increase in notification and decrease in end-to-end delay. The RAP scheme also reduces infrastructure cost (number of RSUs) by formulating and deploying the VBN structure. The RAP scheme with VBN structure improves notification by 19 percent and end-to-end delay by 14.38 percent for a vehicle density of 160 vehicles. It is also proved from the simulation experiment that the performance of RAP scheme is promising in 4-lane highway roads.

  19. Road Accident Prevention with Instant Emergency Warning Message Dissemination in Vehicular Ad-Hoc Network

    PubMed Central

    P, Gokulakrishnan; P, Ganeshkumar

    2015-01-01

    A Road Accident Prevention (RAP) scheme based on Vehicular Backbone Network (VBN) structure is proposed in this paper for Vehicular Ad-hoc Network (VANET). The RAP scheme attempts to prevent vehicles from highway road traffic accidents and thereby reduces death and injury rates. Once the possibility of an emergency situation (i.e. an accident) is predicted in advance, instantly RAP initiates a highway road traffic accident prevention scheme. The RAP scheme constitutes the following activities: (i) the Road Side Unit (RSU) constructs a Prediction Report (PR) based on the status of the vehicles and traffic in the highway roads, (ii) the RSU generates an Emergency Warning Message (EWM) based on an abnormal PR, (iii) the RSU forms a VBN structure and (iv) the RSU disseminates the EWM to the vehicles that holds the high Risk Factor (RF) and travels in High Risk Zone (HRZ). These vehicles might reside either within the RSU’s coverage area or outside RSU’s coverage area (reached using VBN structure). The RAP scheme improves the performance of EWM dissemination in terms of increase in notification and decrease in end-to-end delay. The RAP scheme also reduces infrastructure cost (number of RSUs) by formulating and deploying the VBN structure. The RAP scheme with VBN structure improves notification by 19 percent and end-to-end delay by 14.38 percent for a vehicle density of 160 vehicles. It is also proved from the simulation experiment that the performance of RAP scheme is promising in 4-lane highway roads. PMID:26636576

  20. Fuzzy Logic-based Intelligent Scheme for Enhancing QoS of Vertical Handover Decision in Vehicular Ad-hoc Networks

    NASA Astrophysics Data System (ADS)

    Azzali, F.; Ghazali, O.; Omar, M. H.

    2017-08-01

    The design of next generation networks in various technologies under the “Anywhere, Anytime” paradigm offers seamless connectivity across different coverage. A conventional algorithm such as RSSThreshold algorithm, that only uses the received strength signal (RSS) as a metric, will decrease handover performance regarding handover latency, delay, packet loss, and handover failure probability. Moreover, the RSS-based algorithm is only suitable for horizontal handover decision to examine the quality of service (QoS) compared to the vertical handover decision in advanced technologies. In the next generation network, vertical handover can be started based on the user’s convenience or choice rather than connectivity reasons. This study proposes a vertical handover decision algorithm that uses a Fuzzy Logic (FL) algorithm, to increase QoS performance in heterogeneous vehicular ad-hoc networks (VANET). The study uses network simulator 2.29 (NS 2.29) along with the mobility traffic network and generator to implement simulation scenarios and topologies. This helps the simulation to achieve a realistic VANET mobility scenario. The required analysis on the performance of QoS in the vertical handover can thus be conducted. The proposed Fuzzy Logic algorithm shows improvement over the conventional algorithm (RSSThreshold) in the average percentage of handover QoS whereby it achieves 20%, 21% and 13% improvement on handover latency, delay, and packet loss respectively. This is achieved through triggering a process in layer two and three that enhances the handover performance.

  1. Ad Hoc Conference on the Education of Migrants: Introductory Report on Theme I, "The Position of the Immigrant and His Family on Arrival in the Host Country" (Strasbourg, France, November 5-8, 1974).

    ERIC Educational Resources Information Center

    Morin, Emma

    Theme I of the Ad Hoc Conference on the Education of Migrants was "measures to improve the position of the immigrant and his family at the time of arrival in the host country (including measures taken in the sending country on behalf of those intending to emigrate), primarily in respect of their educational circumstances". This report…

  2. The Kuroshio Extension low-frequency variability analyzed with altimeter data through an ad hoc composite index

    NASA Astrophysics Data System (ADS)

    Pierini, Stefano; Gentile, Vittorio; de Ruggiero, Paola; Pietranera, Luca

    2017-04-01

    The Kuroshio Extension (KE) low-frequency variability (LFV) is analyzed with the satellite altimeter data distributed by AVISO from January 1993 to November 2015 through a new ad hoc composite index [1] that links the mean latitudinal position L of the KE jet and an integrated wavelet amplitude A measuring the high-frequency variability (HFV) of the KE path. This approach allows one to follow the KE evolution as an orbit in the (L,A) plane, as typically done in dynamical systems theory. Three intervals, I1 (1993-1998), I2 (1998-2006) and I3 (2006-November 2015) are separately analyzed also with sea surface height (SSH) maps. In I1 and I3, L and A are mostly anti-correlated and a recharging phase (characterized by a weak convoluted jet experiencing a rapid increase of the HFV) begins when negative SSH anomalies, remotely generated by the Pacific Decadal Oscillation, reach the KE region. On the other hand, in I2 the KE evolution is described by a hysteresis loop: this starts with a weak jet state followed by a recharging phase leading, in turn, to a persistent two-meander state, to its progressive and rapid erosion and, eventually, to the reestablishment of a weak jet state. This loop is found to correspond quite closely to the highly nonlinear intrinsic relaxation oscillation obtained in numerical process studies [1,2]. This supports the hypothesis that the KE LFV may have been controlled, during I2, by an intrinsic oceanic mode of variability. [1] Pierini S., 2015. J. Climate, 28, 5873-5881. [2] Pierini S., 2006. J. Phys. Oceanogr., 36, 1605-1625.

  3. Emergency Situation Prediction Mechanism: A Novel Approach for Intelligent Transportation System Using Vehicular Ad Hoc Networks

    PubMed Central

    Gokulakrishnan, P.

    2015-01-01

    In Indian four-lane express highway, millions of vehicles are travelling every day. Accidents are unfortunate and frequently occurring in these highways causing deaths, increase in death toll, and damage to infrastructure. A mechanism is required to avoid such road accidents at the maximum to reduce the death toll. An Emergency Situation Prediction Mechanism, a novel and proactive approach, is proposed in this paper for achieving the best of Intelligent Transportation System using Vehicular Ad Hoc Network. ESPM intends to predict the possibility of occurrence of an accident in an Indian four-lane express highway. In ESPM, the emergency situation prediction is done by the Road Side Unit based on (i) the Status Report sent by the vehicles in the range of RSU and (ii) the road traffic flow analysis done by the RSU. Once the emergency situation or accident is predicted in advance, an Emergency Warning Message is constructed and disseminated to all vehicles in the area of RSU to alert and prevent the vehicles from accidents. ESPM performs well in emergency situation prediction in advance to the occurrence of an accident. ESPM predicts the emergency situation within 0.20 seconds which is comparatively less than the statistical value. The prediction accuracy of ESPM against vehicle density is found better in different traffic scenarios. PMID:26065014

  4. An evidence-based unified definition of lifelong and acquired premature ejaculation: report of the second international society for sexual medicine ad hoc committee for the definition of premature ejaculation.

    PubMed

    Serefoglu, Ege Can; McMahon, Chris G; Waldinger, Marcel D; Althof, Stanley E; Shindel, Alan; Adaikan, Ganesh; Becher, Edgardo F; Dean, John; Giuliano, Francois; Hellstrom, Wayne Jg; Giraldi, Annamaria; Glina, Sidney; Incrocci, Luca; Jannini, Emmanuele; McCabe, Marita; Parish, Sharon; Rowland, David; Segraves, R Taylor; Sharlip, Ira; Torres, Luiz Otavio

    2014-06-01

    ISSM unified definition of lifelong and acquired PE represents the first evidence-based definition for these conditions. This definition will enable researchers to design methodologically rigorous studies to improve our understanding of acquired PE. Serefoglu EC, McMahon CG, Waldinger MD, Althof SE, Shindel A, Adaikan G, Becher EF, Dean J, Giuliano F, Hellstrom WJG, Giraldi A, Glina S, Incrocci L, Jannini E, McCabe M, Parish S, Rowland D, Segraves RT, Sharlip I, and Torres LO. An evidence-based unified definition of lifelong and acquired premature ejaculation: Report of the second International Society for Sexual Medicine Ad Hoc Committee for the Definition of Premature Ejaculation. Sex Med 2014;2:41-59.

  5. An Evidence-Based Unified Definition of Lifelong and Acquired Premature Ejaculation: Report of the Second International Society for Sexual Medicine Ad Hoc Committee for the Definition of Premature Ejaculation

    PubMed Central

    Serefoglu, Ege Can; McMahon, Chris G; Waldinger, Marcel D; Althof, Stanley E; Shindel, Alan; Adaikan, Ganesh; Becher, Edgardo F; Dean, John; Giuliano, Francois; Hellstrom, Wayne JG; Giraldi, Annamaria; Glina, Sidney; Incrocci, Luca; Jannini, Emmanuele; McCabe, Marita; Parish, Sharon; Rowland, David; Segraves, R Taylor; Sharlip, Ira; Torres, Luiz Otavio

    2014-01-01

    avoidance of sexual intimacy. Conclusion The ISSM unified definition of lifelong and acquired PE represents the first evidence-based definition for these conditions. This definition will enable researchers to design methodologically rigorous studies to improve our understanding of acquired PE. Serefoglu EC, McMahon CG, Waldinger MD, Althof SE, Shindel A, Adaikan G, Becher EF, Dean J, Giuliano F, Hellstrom WJG, Giraldi A, Glina S, Incrocci L, Jannini E, McCabe M, Parish S, Rowland D, Segraves RT, Sharlip I, and Torres LO. An evidence-based unified definition of lifelong and acquired premature ejaculation: Report of the second International Society for Sexual Medicine Ad Hoc Committee for the Definition of Premature Ejaculation. Sex Med 2014;2:41–59. PMID:25356301

  6. Services oriented architectures and rapid deployment of ad-hoc health surveillance systems: lessons from Katrina relief efforts.

    PubMed

    Mirhaji, Parsa; Casscells, S Ward; Srinivasan, Arunkumar; Kunapareddy, Narendra; Byrne, Sean; Richards, David Mark; Arafat, Raouf

    2006-01-01

    During the Hurricane Katrina relief efforts, a new city was born overnight within the City of Houston to provide accommodation and health services for thousands of evacuees deprived of food, rest, medical attention, and sanitation. The hurricane victims had been exposed to flood water, toxic materials, physical injury, and mental stress. This scenario was an invitation for a variety of public health hazards, primarily infectious disease outbreaks. Early detection and monitoring of morbidity and mortality among evacuees due to unattended health conditions was an urgent priority and called for deployment of real-time surveillance to collect and analyze data at the scene, and to enable and guide appropriate response and planning activities. The University of Texas Health Science Center at Houston (UTHSC) and the Houston Department of Health and Human Services (HDHHS) deployed an ad hoc surveillance system overnight by leveraging Internet-based technologies and Services Oriented Architecture (SOA). The system was post-coordinated through the orchestration of Web Services such as information integration, natural language processing, syndromic case finding, and online analytical processing (OLAP). Here we will report the use of Internet-based and distributed architectures in providing timely, novel, and customizable solutions on demand for unprecedented events such as natural disasters.

  7. Dynamic Key Management Schemes for Secure Group Access Control Using Hierarchical Clustering in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Tsaur, Woei-Jiunn; Pai, Haw-Tyng

    2008-11-01

    The applications of group computing and communication motivate the requirement to provide group access control in mobile ad hoc networks (MANETs). The operation in MANETs' groups performs a decentralized manner and accommodated membership dynamically. Moreover, due to lack of centralized control, MANETs' groups are inherently insecure and vulnerable to attacks from both within and outside the groups. Such features make access control more challenging in MANETs. Recently, several researchers have proposed group access control mechanisms in MANETs based on a variety of threshold signatures. However, these mechanisms cannot actually satisfy MANETs' dynamic environments. This is because the threshold-based mechanisms cannot be achieved when the number of members is not up to the threshold value. Hence, by combining the efficient elliptic curve cryptosystem, self-certified public key cryptosystem and secure filter technique, we construct dynamic key management schemes based on hierarchical clustering for securing group access control in MANETs. Specifically, the proposed schemes can constantly accomplish secure group access control only by renewing the secure filters of few cluster heads, when a cluster head joins or leaves a cross-cluster. In such a new way, we can find that the proposed group access control scheme can be very effective for securing practical applications in MANETs.

  8. Estimating HIV Incidence during Pregnancy and Knowledge of Prevention of Mother-to-Child Transmission with an Ad Hoc Analysis of Potential Cofactors.

    PubMed

    Egbe, Thomas Obinchemti; Tazinya, Rose-Mary Asong; Halle-Ekane, Gregory Edie; Egbe, Eta-Nkongho; Achidi, Eric Akum

    2016-01-01

    We determined the incidence of HIV seroconversion during the second and third trimesters of pregnancy and ad hoc potential cofactors associated with HIV seroconversion after having an HIV-negative result antenatally. We also studied knowledge of PMTCT among pregnant women in seven health facilities in Fako Division, South West Region, Cameroon. During the period between September 12 and December 4, 2011, we recruited a cohort of 477 HIV-negative pregnant women by cluster sampling. Data collection was with a pretested interviewer-administered questionnaire. Sociodemographic information, knowledge of PMTCT, and methods of HIV prevention were obtained from the study population and we did Voluntary Counselling and Testing (VCT) for HIV. The incidence rate of HIV seroconversion during pregnancy was 6.8/100 woman-years. Ninety percent of the participants did not use condoms throughout pregnancy but had a good knowledge of PMTCT of HIV. Only 31.9% of participants knew their HIV status before the booking visit and 33% did not know the HIV status of their partners. The incidence rate of HIV seroconversion in the Fako Division, Cameroon, was 6.8/100 woman-years. No risk factors associated with HIV seroconversion were identified among the study participants because of lack of power to do so.

  9. Cluster Based Location-Aided Routing Protocol for Large Scale Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Dong, Liang; Liang, Taotao; Yang, Xinyu; Zhang, Deyun

    Routing algorithms with low overhead, stable link and independence of the total number of nodes in the network are essential for the design and operation of the large-scale wireless mobile ad hoc networks (MANET). In this paper, we develop and analyze the Cluster Based Location-Aided Routing Protocol for MANET (C-LAR), a scalable and effective routing algorithm for MANET. C-LAR runs on top of an adaptive cluster cover of the MANET, which can be created and maintained using, for instance, the weight-based distributed algorithm. This algorithm takes into consideration the node degree, mobility, relative distance, battery power and link stability of mobile nodes. The hierarchical structure stabilizes the end-to-end communication paths and improves the networks' scalability such that the routing overhead does not become tremendous in large scale MANET. The clusterheads form a connected virtual backbone in the network, determine the network's topology and stability, and provide an efficient approach to minimizing the flooding traffic during route discovery and speeding up this process as well. Furthermore, it is fascinating and important to investigate how to control the total number of nodes participating in a routing establishment process so as to improve the network layer performance of MANET. C-LAR is to use geographical location information provided by Global Position System to assist routing. The location information of destination node is used to predict a smaller rectangle, isosceles triangle, or circle request zone, which is selected according to the relative location of the source and the destination, that covers the estimated region in which the destination may be located. Thus, instead of searching the route in the entire network blindly, C-LAR confines the route searching space into a much smaller estimated range. Simulation results have shown that C-LAR outperforms other protocols significantly in route set up time, routing overhead, mean delay and packet

  10. Obtaining appropriate interval estimates for age when multiple indicators are used: evaluation of an ad-hoc procedure.

    PubMed

    Fieuws, Steffen; Willems, Guy; Larsen-Tangmose, Sara; Lynnerup, Niels; Boldsen, Jesper; Thevissen, Patrick

    2016-03-01

    When an estimate of age is needed, typically multiple indicators are present as found in skeletal or dental information. There exists a vast literature on approaches to estimate age from such multivariate data. Application of Bayes' rule has been proposed to overcome drawbacks of classical regression models but becomes less trivial as soon as the number of indicators increases. Each of the age indicators can lead to a different point estimate ("the most plausible value for age") and a prediction interval ("the range of possible values"). The major challenge in the combination of multiple indicators is not the calculation of a combined point estimate for age but the construction of an appropriate prediction interval. Ignoring the correlation between the age indicators results in intervals being too small. Boldsen et al. (2002) presented an ad-hoc procedure to construct an approximate confidence interval without the need to model the multivariate correlation structure between the indicators. The aim of the present paper is to bring under attention this pragmatic approach and to evaluate its performance in a practical setting. This is all the more needed since recent publications ignore the need for interval estimation. To illustrate and evaluate the method, Köhler et al. (1995) third molar scores are used to estimate the age in a dataset of 3200 male subjects in the juvenile age range.

  11. SPAR: a security- and power-aware routing protocol for wireless ad hoc and sensor networks

    NASA Astrophysics Data System (ADS)

    Oberoi, Vikram; Chigan, Chunxiao

    2005-05-01

    Wireless Ad Hoc and Sensor Networks (WAHSNs) are vulnerable to extensive attacks as well as severe resource constraints. To fulfill the security needs, many security enhancements have been proposed. Like wise, from resource constraint perspective, many power aware schemes have been proposed to save the battery power. However, we observe that for the severely resource limited and extremely vulnerable WAHSNs, taking security or power (or any other resource) alone into consideration for protocol design is rather inadequate toward the truly "secure-and-useful" WAHSNs. For example, from resource constraint perspective, we identify one of the potential problems, the Security-Capable-Congestion (SCC) behavior, for the WAHSNs routing protocols where only the security are concerned. On the other hand, the design approach where only scarce resource is concerned, such as many power-aware WAHSNs protocols, leaves security unconsidered and is undesirable to many WAHSNs application scenarios. Motivated by these observations, we propose a co-design approach, where both the high security and effective resource consumption are targeted for WAHSNs protocol design. Specifically, we propose a novel routing protocol, Security- and Power- Aware Routing (SPAR) protocol based on this co-design approach. In SPAR, the routing decisions are made based on both security and power as routing criteria. The idea of the SPAR mechanism is routing protocol independent and therefore can be broadly integrated into any of the existing WAHSNs routing protocols. The simulation results show that SPAR outperforms the WAHSNs routing protocols where security or power alone is considered, significantly. This research finding demonstrates the proposed security- and resource- aware co-design approach is promising towards the truly "secure-and-useful" WAHSNs.

  12. Unsupervised algorithms for intrusion detection and identification in wireless ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2009-05-01

    In previous work by the author, parameters across network protocol layers were selected as features in supervised algorithms that detect and identify certain intrusion attacks on wireless ad hoc sensor networks (WSNs) carrying multisensor data. The algorithms improved the residual performance of the intrusion prevention measures provided by any dynamic key-management schemes and trust models implemented among network nodes. The approach of this paper does not train algorithms on the signature of known attack traffic, but, instead, the approach is based on unsupervised anomaly detection techniques that learn the signature of normal network traffic. Unsupervised learning does not require the data to be labeled or to be purely of one type, i.e., normal or attack traffic. The approach can be augmented to add any security attributes and quantified trust levels, established during data exchanges among nodes, to the set of cross-layer features from the WSN protocols. A two-stage framework is introduced for the security algorithms to overcome the problems of input size and resource constraints. The first stage is an unsupervised clustering algorithm which reduces the payload of network data packets to a tractable size. The second stage is a traditional anomaly detection algorithm based on a variation of support vector machines (SVMs), whose efficiency is improved by the availability of data in the packet payload. In the first stage, selected algorithms are adapted to WSN platforms to meet system requirements for simple parallel distributed computation, distributed storage and data robustness. A set of mobile software agents, acting like an ant colony in securing the WSN, are distributed at the nodes to implement the algorithms. The agents move among the layers involved in the network response to the intrusions at each active node and trustworthy neighborhood, collecting parametric values and executing assigned decision tasks. This minimizes the need to move large amounts

  13. Design and Analysis of A Beacon-Less Routing Protocol for Large Volume Content Dissemination in Vehicular Ad Hoc Networks.

    PubMed

    Hu, Miao; Zhong, Zhangdui; Ni, Minming; Baiocchi, Andrea

    2016-11-01

    Large volume content dissemination is pursued by the growing number of high quality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been proven to be efficient in achieving a balance between the system performance and the control overhead. However, to the authors' best knowledge, the routing design for large volume content has not been well considered in the previous work, which will introduce new challenges, e.g., the enhanced connectivity requirement for a radio link. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is designed for large volume content delivery in VANETs. Each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information. A semi-Markov process analytical model is proposed to evaluate the expected delay in constructing one routing path for LBRP. Simulations show that the proposed LBRP scheme outperforms the traditional dissemination protocols in providing a low end-to-end delay. The analytical model is shown to exhibit a good match on the delay estimation with Monte Carlo simulations, as well.

  14. Design and Analysis of A Beacon-Less Routing Protocol for Large Volume Content Dissemination in Vehicular Ad Hoc Networks

    PubMed Central

    Hu, Miao; Zhong, Zhangdui; Ni, Minming; Baiocchi, Andrea

    2016-01-01

    Large volume content dissemination is pursued by the growing number of high quality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been proven to be efficient in achieving a balance between the system performance and the control overhead. However, to the authors’ best knowledge, the routing design for large volume content has not been well considered in the previous work, which will introduce new challenges, e.g., the enhanced connectivity requirement for a radio link. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is designed for large volume content delivery in VANETs. Each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information. A semi-Markov process analytical model is proposed to evaluate the expected delay in constructing one routing path for LBRP. Simulations show that the proposed LBRP scheme outperforms the traditional dissemination protocols in providing a low end-to-end delay. The analytical model is shown to exhibit a good match on the delay estimation with Monte Carlo simulations, as well. PMID:27809285

  15. Hearings before the Ad Hoc Committee on Maritime Education and Training of the Committee on Merchant Marine and Fisheries, Ninety-Third Congress; Second Session on Officer Requirements, and Session on Maritime Education Regarding Safety at Sea. Serial No. 93-44.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. House Committee on Merchant Marine and Fisheries.

    The publication consists of Congressional hearings before the Ad Hoc Committee on Maritime Education and Training: (1) June 26, 1974 hearing pertaining to officer requirements and (2) November 19, 1974 hearing on maritime education regarding safety at sea. Estimated cost per graduate for the U. S. Merchant Marine 1973 class was $31,100. Supply and…

  16. Lentiviral haemopoietic stem-cell gene therapy in early-onset metachromatic leukodystrophy: an ad-hoc analysis of a non-randomised, open-label, phase 1/2 trial.

    PubMed

    Sessa, Maria; Lorioli, Laura; Fumagalli, Francesca; Acquati, Serena; Redaelli, Daniela; Baldoli, Cristina; Canale, Sabrina; Lopez, Ignazio D; Morena, Francesco; Calabria, Andrea; Fiori, Rossana; Silvani, Paolo; Rancoita, Paola M V; Gabaldo, Michela; Benedicenti, Fabrizio; Antonioli, Gigliola; Assanelli, Andrea; Cicalese, Maria Pia; Del Carro, Ubaldo; Sora, Maria Grazia Natali; Martino, Sabata; Quattrini, Angelo; Montini, Eugenio; Di Serio, Clelia; Ciceri, Fabio; Roncarolo, Maria Grazia; Aiuti, Alessandro; Naldini, Luigi; Biffi, Alessandra

    2016-07-30

    Metachromatic leukodystrophy (a deficiency of arylsulfatase A [ARSA]) is a fatal demyelinating lysosomal disease with no approved treatment. We aimed to assess the long-term outcomes in a cohort of patients with early-onset metachromatic leukodystrophy who underwent haemopoietic stem-cell gene therapy (HSC-GT). This is an ad-hoc analysis of data from an ongoing, non-randomised, open-label, single-arm phase 1/2 trial, in which we enrolled patients with a molecular and biochemical diagnosis of metachromatic leukodystrophy (presymptomatic late-infantile or early-juvenile disease or early-symptomatic early-juvenile disease) at the Paediatric Clinical Research Unit, Ospedale San Raffaele, in Milan. Trial participants received HSC-GT, which consisted of the infusion of autologous HSCs transduced with a lentiviral vector encoding ARSA cDNA, after exposure-targeted busulfan conditioning. The primary endpoints of the trial are safety (toxicity, absence of engraftment failure or delayed haematological reconstitution, and safety of lentiviral vector-tranduced cell infusion) and efficacy (improvement in Gross Motor Function Measure [GMFM] score relative to untreated historical controls, and ARSA activity, 24 months post-treatment) of HSC-GT. For this ad-hoc analysis, we assessed safety and efficacy outcomes in all patients who had received treatment and been followed up for at least 18 months post-treatment on June 1, 2015. This trial is registered with ClinicalTrials.gov, number NCT01560182. Between April, 2010, and February, 2013, we had enrolled nine children with a diagnosis of early-onset disease (six had late-infantile disease, two had early-juvenile disease, and one had early-onset disease that could not be definitively classified). At the time of analysis all children had survived, with a median follow-up of 36 months (range 18-54). The most commonly reported adverse events were cytopenia (reported in all patients) and mucositis of different grades of severity (in five

  17. On the Post Hoc Power in Testing Mean Differences

    ERIC Educational Resources Information Center

    Yuan, Ke-Hai; Maxwell, Scott

    2005-01-01

    Retrospective or post hoc power analysis is recommended by reviewers and editors of many journals. Little literature has been found that gave a serious study of the post hoc power. When the sample size is large, the observed effect size is a good estimator of the true power. This article studies whether such a power estimator provides valuable…

  18. An evidence-based unified definition of lifelong and acquired premature ejaculation: report of the second International Society for Sexual Medicine Ad Hoc Committee for the Definition of Premature Ejaculation.

    PubMed

    Serefoglu, Ege Can; McMahon, Chris G; Waldinger, Marcel D; Althof, Stanley E; Shindel, Alan; Adaikan, Ganesh; Becher, Edgardo F; Dean, John; Giuliano, Francois; Hellstrom, Wayne J G; Giraldi, Annamaria; Glina, Sidney; Incrocci, Luca; Jannini, Emmanuele; McCabe, Marita; Parish, Sharon; Rowland, David; Segraves, R Taylor; Sharlip, Ira; Torres, Luiz Otavio

    2014-06-01

    The International Society for Sexual Medicine (ISSM) Ad Hoc Committee for the Definition of Premature Ejaculation developed the first evidence-based definition for lifelong premature ejaculation (PE) in 2007 and concluded that there were insufficient published objective data at that time to develop a definition for acquired PE. The aim of this article is to review and critique the current literature and develop a contemporary, evidence-based definition for acquired PE and/or a unified definition for both lifelong and acquired PE. In April 2013, the ISSM convened a second Ad Hoc Committee for the Definition of Premature Ejaculation in Bangalore, India. The same evidence-based systematic approach to literature search, retrieval, and evaluation used by the original committee was adopted. The committee unanimously agreed that men with lifelong and acquired PE appear to share the dimensions of short ejaculatory latency, reduced or absent perceived ejaculatory control, and the presence of negative personal consequences. Men with acquired PE are older, have higher incidences of erectile dysfunction, comorbid disease, and cardiovascular risk factors, and have a longer intravaginal ejaculation latency time (IELT) as compared with men with lifelong PE. A self-estimated or stopwatch IELT of 3 minutes was identified as a valid IELT cut-off for diagnosing acquired PE. On this basis, the committee agreed on a unified definition of both acquired and lifelong PE as a male sexual dysfunction characterized by (i) ejaculation that always or nearly always occurs prior to or within about 1 minute of vaginal penetration from the first sexual experience (lifelong PE) or a clinically significant and bothersome reduction in latency time, often to about 3 minutes or less (acquired PE); (ii) the inability to delay ejaculation on all or nearly all vaginal penetrations; and (iii) negative personal consequences, such as distress, bother, frustration, and/or the avoidance of sexual intimacy. The

  19. Ad Hoc Influenza Vaccination During Years of Significant Antigenic Drift in a Tropical City With 2 Seasonal Peaks: A Cross-Sectional Survey Among Health Care Practitioners.

    PubMed

    Wong, Martin C S; Nelson, E Anthony S; Leung, Czarina; Lee, Nelson; Chan, Martin C W; Choi, Kin Wing; Rainer, Timothy H; Cheng, Frankie W T; Wong, Samuel Y S; Lai, Christopher K C; Lam, Bosco; Cheung, Tak Hong; Leung, Ting Fan; Chan, Paul K S

    2016-05-01

    We evaluated the acceptability of an additional ad hoc influenza vaccination among the health care professionals following seasons with significant antigenic drift.Self-administered, anonymous surveys were performed by hard copy questionnaires in public hospitals, and by an on-line platform available to all healthcare professionals, from April 1st to May 31st, 2015. A total of 1290 healthcare professionals completed the questionnaires, including doctors, nurses, and allied health professionals working in both the public and private systems.Only 31.8% of participating respondents expressed an intention to receive the additional vaccine, despite that the majority of them agreed or strongly agreed that it would bring benefit to the community (88.9%), save lives (86.7%), reduce medical expenses (76.3%), satisfy public expectation (82.8%), and increase awareness of vaccination (86.1%). However, a significant proportion expressed concern that the vaccine could disturb the normal immunization schedule (45.5%); felt uncertain what to do in the next vaccination round (66.0%); perceived that the summer peak might not occur (48.2%); and believed that the summer peak might not be of the same virus (83.5%). Furthermore, 27.8% of all respondents expected that the additional vaccination could weaken the efficacy of previous vaccinations; 51.3% was concerned about side effects; and 61.3% estimated that there would be a low uptake rate. If the supply of vaccine was limited, higher priority groups were considered to include the elderly aged ≥65 years with chronic medical conditions (89.2%), the elderly living in residential care homes (87.4%), and long-stay residents of institutions for the disabled (80.7%). The strongest factors associated with accepting the additional vaccine included immunization with influenza vaccines in the past 3 years, higher perceived risk of contracting influenza, and higher perceived severity of the disease impact.The acceptability to an additional ad

  20. Infrared spectra of two isomers of protonated carbonyl sulfide (HOCS+ and HSCO+) and t-HOCS in solid para-hydrogen.

    PubMed

    Tsuge, Masashi; Lee, Yuan-Pern

    2016-10-28

    We report infrared (IR) spectra of HOCS + , HSCO + , t-HOCS, and other species produced on electron bombardment of a mixture of carbonyl sulfide (OCS) and para-hydrogen (p-H 2 ) during deposition at 3.2 K. After maintenance of the matrix in darkness for 15 h, the intensities of absorption features of HOCS + at 2945.9 (ν 1 ), 1875.3 (ν 2 ), and 1041.9 (ν 3 ) cm -1 and those of HSCO + at 2506.9 (ν 1 ) and 2074.2 (ν 2 ) cm -1 decreased through neutralization with trapped electrons. Lines observed at 3563.4, 1394.8, and 1199.0 cm -1 , which decreased slightly in intensity after maintenance in darkness and were nearly depleted after irradiation at 373 nm, are assigned to a t-HOCS radical. The corresponding spectra of their 13 C- and D-isotopologues were observed. The IR spectra of HSCO + and t-HOCS and those of modes ν 2 and ν 3 of HOCS + are new. The assignments were made according to the expected chemical behavior and a comparison of experimental and calculated wavenumbers and 13 C- and D-isotopic shifts. The wavenumber of the OH stretching mode (2945.9 cm -1 ) of HOCS + in solid p-H 2 is significantly red-shifted from that (3435.16 cm -1 ) reported for gaseous HOCS + ; this shift is attributed to partial sharing of a proton between OCS and H 2 . The corresponding p-H 2 induced shift is small in HSCO + because of a much weaker interaction between HSCO + and H 2 .

  1. Evaluation of absorbent materials for use as ad hoc dry decontaminants during mass casualty incidents as part of the UK’s Initial Operational Response (IOR)

    PubMed Central

    Kassouf, Nick; Syed, Sara; Larner, Joanne; Amlôt, Richard

    2017-01-01

    The UK’s Initial Operational Response (IOR) is a revised process for the medical management of mass casualties potentially contaminated with hazardous materials. A critical element of the IOR is the introduction of immediate, on-scene disrobing and decontamination of casualties to limit the adverse health effects of exposure. Ad hoc cleansing of the skin with dry absorbent materials has previously been identified as a potential means of facilitating emergency decontamination. The purpose of this study was to evaluate the in vitro oil and water absorbency of a range of materials commonly found in the domestic and clinical environments and to determine the effectiveness of a small, but representative selection of such materials in skin decontamination, using an established ex vivo model. Five contaminants were used in the study: methyl salicylate, parathion, diethyl malonate, phorate and potassium cyanide. In vitro measurements of water and oil absorbency did not correlate with ex vivo measurements of skin decontamination. When measured ex vivo, dry decontamination was consistently more effective than a standard wet decontamination method (“rinse-wipe-rinse”) for removing liquid contaminants. However, dry decontamination was ineffective against particulate contamination. Collectively, these data confirm that absorbent materials such as wound dressings and tissue paper provide an effective, generic capability for emergency removal of liquid contaminants from the skin surface, but that wet decontamination should be used for non-liquid contaminants. PMID:28152053

  2. IDMA: improving the defense against malicious attack for mobile ad hoc networks based on ARIP protocol

    NASA Astrophysics Data System (ADS)

    Peng, Chaorong; Chen, Chang Wen

    2008-04-01

    Malicious nodes are mounting increasingly sophisticated attacking operations on the Mobile Ad Hoc Networks (MANETs). This is mainly because the IP-based MANETs are vulnerable to attacks by various malicious nodes. However, the defense against malicious attack can be improved when a new layer of network architecture can be developed to separate true IP address from disclosing to the malicious nodes. In this paper, we propose a new algorithm to improve the defense against malicious attack (IDMA) that is based on a recently developed Assignment Router Identify Protocol (ARIP) for the clustering-based MANET management. In the ARIP protocol, we design the ARIP architecture based on the new Identity instead of the vulnerable IP addresses to provide the required security that is embedded seamlessly into the overall network architecture. We make full use of ARIP's special property to monitor gateway forward packets by Reply Request Route Packets (RREP) without additional intrusion detection layer. We name this new algorithm IDMA because of its inherent capability to improve the defense against malicious attacks. Through IDMA, a watching algorithm can be established so as to counterattack the malicious node in the routing path when it unusually drops up packets. We provide analysis examples for IDMA for the defense against a malicious node that disrupts the route discovery by impersonating the destination, or by responding with state of corrupted routing information, or by disseminating forged control traffic. The IDMA algorithm is able to counterattack the malicious node in the cases when the node lunch DoS attack by broadcast a large number of route requests, or make Target traffic congestion by delivering huge mount of data; or spoof the IP addresses and send forge packets with a fake ID to the same Target causing traffic congestion at that destination. We have implemented IDMA algorism using the GloMoSim simulator and have demonstrated its performance under a variety of

  3. Algorithmic, LOCS and HOCS (chemistry) exam questions: performance and attitudes of college students

    NASA Astrophysics Data System (ADS)

    Zoller, Uri

    2002-02-01

    The performance of freshmen biology and physics-mathematics majors and chemistry majors as well as pre- and in-service chemistry teachers in two Israeli universities on algorithmic (ALG), lower-order cognitive skills (LOCS), and higher-order cognitive skills (HOCS) chemistry exam questions were studied. The driving force for the study was an interest in moving science and chemistry instruction from an algorithmic and factual recall orientation dominated by LOCS, to a decision-making, problem-solving and critical system thinking approach, dominated by HOCS. College students' responses to the specially designed ALG, LOCS and HOCS chemistry exam questions were scored and analysed for differences and correlation between the performance means within and across universities by the questions' category. This was followed by a combined student interview - 'speaking aloud' problem solving session for assessing the thinking processes involved in solving these types of questions and the students' attitudes towards them. The main findings were: (1) students in both universities performed consistently in each of the three categories in the order of ALG > LOCS > HOCS; their 'ideological' preference, was HOCS > algorithmic/LOCS, - referred to as 'computational questions', but their pragmatic preference was the reverse; (2) success on algorithmic/LOCS does not imply success on HOCS questions; algorithmic questions constitute a category on its own as far as students success in solving them is concerned. Our study and its results support the effort being made, worldwide, to integrate HOCS-fostering teaching and assessment strategies and, to develop HOCS-oriented science-technology-environment-society (STES)-type curricula within science and chemistry education.

  4. Ad-hoc surface-enhanced Raman spectroscopy methodologies for the detection of artist dyestuffs: thin layer chromatography-surface enhanced Raman spectroscopy and in situ on the fiber analysis.

    PubMed

    Brosseau, Christa L; Gambardella, Alessa; Casadio, Francesca; Grzywacz, Cecily M; Wouters, Jan; Van Duyne, Richard P

    2009-04-15

    Tailored ad-hoc methods must be developed for successful identification of minute amounts of natural dyes on works of art using Surface-Enhanced Raman Spectroscopy (SERS). This article details two of these successful approaches using silver film over nanosphere (AgFON) substrates and silica gel coupled with citrate-reduced Ag colloids. The latter substrate functions as the test system for the coupling of thin-layer chromatography and SERS (TLC-SERS), which has been used in the current research to separate and characterize a mixture of several artists' dyes. The poor limit of detection of TLC is overcome by coupling with SERS, and dyes which co-elute to nearly the same spot can be distinguished from each other. In addition, in situ extractionless non-hydrolysis SERS was used to analyze dyed reference fibers, as well as historical textile fibers. Colorants such as alizarin, purpurin, carminic acid, lac dye, crocin, and Cape jasmine were thus successfully identified.

  5. Army Science Board Ad Hoc Study Group Report on Human Issues.

    DTIC Science & Technology

    1980-03-01

    top level attention on human issues research and to formulate human issues programs to meet future needs. A concept paper was presented to the Army...the Army (Operations Research), 10 spaces were allo- cated to provide in-house research/study capability under the ADCSPER. These 10 spaces should be...combined with the present three- space study and analysis section, thus providing a 13- space group which could support the PPRC, APSC, and DCSPER. In

  6. Ad Hoc Rural Regionalism

    ERIC Educational Resources Information Center

    Hamin, Elisabeth M.; Marcucci, Daniel J.

    2008-01-01

    A new regionalism has been much documented and researched for metropolitan areas; this article documents that there is a new rural regionalism as well. In the United States, these groups appear most likely to emerge in areas that are challenged by outcomes characterizing globalization's effects on the rural condition: namely, exurban or…

  7. Calculations concerning the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Defrees, D. J.; Mclean, A. D.; Herbst, E.

    1984-01-01

    Calculations have been performed to determine the rate coefficients of several reactions involved in both the formation and depletion of interstellar HCO(+) and HOC(+). The abundance of HOC(+) deduced from these calculations is consistent with the tentative identification of HOC(+) in Sgr B2 by Woods et al. (1983). The large HCO(+)/HOC(+) abundance ratio observed by Woods et al. is due at least in part to a more rapid formation rate for HCO(+) and probably due as well to a more rapid depletion rate for HOC(+).

  8. Army Science Board 2001 AD HOC Study Knowledge Management

    DTIC Science & Technology

    2001-11-01

    dissemination, Army, Army culture, information dominance , knowledge dominance, information sharing, situational awareness, network-centric, infosphere...proposed effort and the emerging Army ICT for Information Dominance are all excellent foundation efforts for KM and Information Assurance. The panel’s...level is critical to survivability and lethality. – Unreliable information will quickly reverse the advantages of “ Information Dominance ” essential to

  9. Sea Training at Maritime Academies Oversight. Hearings Before the Ad Hoc Select Subcommittee on Maritime Education and Training of the Committee on Merchant Marine and Fisheries, House of Representatives, Ninety-Sixth Congress, Second Session on Sea Training of United States Merchant Marine Officers and Different Ways of Satisfying This Requirement at the Various Maritime Academies.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. House Committee on Merchant Marine and Fisheries.

    Recorded are minutes of hearings before the House Ad Hoc Select Subcommittee on Maritime Education and Training regarding the sea training of United States Merchant Marine officers. Examined are various approaches to meeting the sea training requirement, especially the options of maritime academy training vessels, sailing on U.S.-flag merchant…

  10. Achieving Congestion Mitigation Using Distributed Power Control for Spectrum Sensor Nodes in Sensor Network-Aided Cognitive Radio Ad Hoc Networks

    PubMed Central

    Zhuo, Fan; Duan, Hucai

    2017-01-01

    The data sequence of spectrum sensing results injected from dedicated spectrum sensor nodes (SSNs) and the data traffic from upstream secondary users (SUs) lead to unpredictable data loads in a sensor network-aided cognitive radio ad hoc network (SN-CRN). As a result, network congestion may occur at a SU acting as fusion center when the offered data load exceeds its available capacity, which degrades network performance. In this paper, we present an effective approach to mitigate congestion of bottlenecked SUs via a proposed distributed power control framework for SSNs over a rectangular grid based SN-CRN, aiming to balance resource load and avoid excessive congestion. To achieve this goal, a distributed power control framework for SSNs from interior tier (IT) and middle tier (MT) is proposed to achieve the tradeoff between channel capacity and energy consumption. In particular, we firstly devise two pricing factors by considering stability of local spectrum sensing and spectrum sensing quality for SSNs. By the aid of pricing factors, the utility function of this power control problem is formulated by jointly taking into account the revenue of power reduction and the cost of energy consumption for IT or MT SSN. By bearing in mind the utility function maximization and linear differential equation constraint of energy consumption, we further formulate the power control problem as a differential game model under a cooperation or noncooperation scenario, and rigorously obtain the optimal solutions to this game model by employing dynamic programming. Then the congestion mitigation for bottlenecked SUs is derived by alleviating the buffer load over their internal buffers. Simulation results are presented to show the effectiveness of the proposed approach under the rectangular grid based SN-CRN scenario. PMID:28914803

  11. Regressive research: The pitfalls of post hoc data selection in the study of unconscious mental processes.

    PubMed

    Shanks, David R

    2017-06-01

    Many studies of unconscious processing involve comparing a performance measure (e.g., some assessment of perception or memory) with an awareness measure (such as a verbal report or a forced-choice response) taken either concurrently or separately. Unconscious processing is inferred when above-chance performance is combined with null awareness. Often, however, aggregate awareness is better than chance, and data analysis therefore employs a form of extreme group analysis focusing post hoc on participants, trials, or items where awareness is absent or at chance. The pitfalls of this analytic approach are described with particular reference to recent research on implicit learning and subliminal perception. Because of regression to the mean, the approach can mislead researchers into erroneous conclusions concerning unconscious influences on behavior. Recommendations are made about future use of post hoc selection in research on unconscious cognition.

  12. Hypnotherapeutic olfactory conditioning (HOC): case studies of needle phobia, panic disorder, and combat-induced PTSD.

    PubMed

    Abramowitz, Eitan G; Lichtenberg, Pesach

    2009-04-01

    The authors developed a technique, which they call hypnotherapeutic olfactory conditioning (HOC), for exploiting the ability of scents to arouse potent emotional reactions. During hypnosis, the patient learns to associate pleasant scents with a sense of security and self-control. The patient can subsequently use this newfound association to overcome phobias and prevent panic attacks. This may be especially effective for posttraumatic stress disorder (PTSD) with episodes of anxiety, flashbacks, and dissociation triggered by smells. The authors present 3 cases, patients with needle phobia, panic disorder, and combat-induced PTSD who were successfully treated with the HOC technique.

  13. Cross-layer design for intrusion detection and data security in wireless ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2007-09-01

    A wireless ad hoc sensor network is a configuration for area surveillance that affords rapid, flexible deployment in arbitrary threat environments. There is no infrastructure support and sensor nodes communicate with each other only when they are in transmission range. The nodes are severely resource-constrained, with limited processing, memory and power capacities and must operate cooperatively to fulfill a common mission in typically unattended modes. In a wireless sensor network (WSN), each sensor at a node can observe locally some underlying physical phenomenon and sends a quantized version of the observation to sink (destination) nodes via wireless links. Since the wireless medium can be easily eavesdropped, links can be compromised by intrusion attacks from nodes that may mount denial-of-service attacks or insert spurious information into routing packets, leading to routing loops, long timeouts, impersonation, and node exhaustion. A cross-layer design based on protocol-layer interactions is proposed for detection and identification of various intrusion attacks on WSN operation. A feature set is formed from selected cross-layer parameters of the WSN protocol to detect and identify security threats due to intrusion attacks. A separate protocol is not constructed from the cross-layer design; instead, security attributes and quantified trust levels at and among nodes established during data exchanges complement customary WSN metrics of energy usage, reliability, route availability, and end-to-end quality-of-service (QoS) provisioning. Statistical pattern recognition algorithms are applied that use observed feature-set patterns observed during network operations, viewed as security audit logs. These algorithms provide the "best" network global performance in the presence of various intrusion attacks. A set of mobile (software) agents distributed at the nodes implement the algorithms, by moving among the layers involved in the network response at each active node

  14. Post hoc analyses: after the facts.

    PubMed

    Srinivas, Titte R; Ho, Bing; Kang, Joseph; Kaplan, Bruce

    2015-01-01

    Prospective clinical trials are constructed with high levels of internal validity. Sample size and power considerations usually address primary endpoints. Primary endpoints have traditionally included events that are becoming increasingly less common and thus have led to growing use of composite endpoints and noninferiority trial designs in transplantation. This approach may mask real clinical benefit in one or the other domain with regard to either clinically relevant secondary endpoints or other unexpected findings. In addition, endpoints solely chosen based on power considerations are prone to misjudgment of actual treatment effect size as well as consistency of that effect. In the instances where treatment effects may have been underestimated, valuable information may be lost if buried within a composite endpoint. In all these cases, analyses and post hoc analyses of data become relevant in informing practitioners about clinical benefits or safety signals that may not be captured by the primary endpoint. On the other hand, there are many pitfalls in using post hoc determined endpoints. This short review is meant to allow readers to appreciate post hoc analysis not as an entity with a single approach, but rather as an analysis with unique limitations and strengths that often raise new questions to be addressed in further inquiries.

  15. A reanalysis of the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Jarrold, M. F.; Bowers, M. T.; Defrees, D. J.; Mclean, A. D.; Herbst, E.

    1986-01-01

    New theoretical and experimental results have prompted a reinvestigation of the HCO(+)/HOC(+) abundance ratio in dense interstellar clouds. These results pertain principally but not exclusively to the reaction between HOC(+) and H2, which was previously calculated by DeFrees et al. (1984) to possess a large activation energy barrier. New calculations, reported here, indicate that this activation energy barrier is quite small and may well be zero. In addition, experimental results at higher energy and temperature indicate strongly that the reaction proceeds efficiently at interstellar temperatures. If HOC(+) does indeed react efficiently with H2 in interstellar clouds, the calculated HCO(+)/HOC(+) abundance ratio rises to a substantially greater value under standard dense cloud conditions than is deduced via the tentative observation of HOC(+) in Sgr B2.

  16. Sembragiline in Moderate Alzheimer’s Disease: Results of a Randomized, Double-Blind, Placebo-Controlled Phase II Trial (MAyflOwer RoAD)

    PubMed Central

    Nave, Stephane; Doody, Rachelle S.; Boada, Mercè; Grimmer, Timo; Savola, Juha-Matti; Delmar, Paul; Pauly-Evers, Meike; Nikolcheva, Tania; Czech, Christian; Borroni, Edilio; Ricci, Benedicte; Dukart, Juergen; Mannino, Marie; Carey, Tracie; Moran, Emma; Gilaberte, Inma; Muelhardt, Nicoletta Milani; Gerlach, Irene; Santarelli, Luca; Ostrowitzki, Susanne; Fontoura, Paulo

    2017-01-01

    Background: Sembragiline is a potent, selective, long-acting, and reversible MAO-B inhibitor developed as a potential treatment for Alzheimer’s disease (AD). Objective: To evaluate the safety, tolerability, and efficacy of sembragiline in patients with moderate AD. Methods: In this Phase II study (NCT01677754), 542 patients with moderate dementia (MMSE 13–20) on background acetylcholinesterase inhibitors with/without memantine were randomized (1:1:1) to sembragiline 1 mg, 5 mg, or placebo once daily orally for 52 weeks. Results: No differences between treated groups and placebo in adverse events or in study completion. The primary endpoint, change from baseline in ADAS-Cog11, was not met. At Week 52, the difference between sembragiline and placebo in ADAS-Cog11 change from baseline was – 0.15 (p = 0.865) and 0.90 (p = 0.312) for 1 and 5 mg groups, respectively. Relative to placebo at Week 52 (but not at prior assessment times), the 1 mg and 5 mg sembragiline groups showed differences in ADCS-ADL of 2.64 (p = 0.051) and 1.89 (p = 0.160), respectively. A treatment effect in neuropsychiatric symptoms (as assessed by the difference between sembragiline and placebo on BEHAVE-AD-FW) was also seen at Week 52 only: – 2.80 (p = 0.014; 1 mg) and – 2.64 (p = 0.019; 5 mg), respectively. A post hoc subgroup analysis revealed greater treatment effects on behavior and functioning in patients with more severe baseline behavioral symptoms (above the median). Conclusions: This study showed that sembragiline was well-tolerated in patients with moderate AD. The study missed its primary and secondary endpoints. Post hoc analyses suggested potential effect on neuropsychiatric symptoms and functioning in more behaviorally impaired study population at baseline. PMID:28550255

  17. The Advantages of Using Planned Comparisons over Post Hoc Tests.

    ERIC Educational Resources Information Center

    Kuehne, Carolyn C.

    There are advantages to using a priori or planned comparisons rather than omnibus multivariate analysis of variance (MANOVA) tests followed by post hoc or a posteriori testing. A small heuristic data set is used to illustrate these advantages. An omnibus MANOVA test was performed on the data followed by a post hoc test (discriminant analysis). A…

  18. Stress at work: development of the Stress Perception Questionnaire of Rome (SPQR), an ad hoc questionnaire for multidimensional assessment of work related stress.

    PubMed

    Cinti, M E; Cannavò, M; Fioravanti, M

    2017-01-01

    Stress is an emotional condition, mostly experienced as negative, initially identified and defined by Selye in the mid-thirties of the last Century. Since the first definition, stress concerns the adaptation pro- cess mostly related to environmental changes. An application of stress focuses on the evaluation of its interference on work conditions, and the scientific evidence on work related stress is very ample and rich. We are proposing a new ad hoc questionnaire for the multidimensional assessment of work related stress, called Stress Perception Question- naire of Rome (SPQR) composed of 50 items. The development of this questionnaire is based on a multi-step process: a) Identification of all the relevant topics to work related stress and areas in the scientific evidence and their transformation on specific contents of 60 tentative items; b) Exploratory factor analysis aimed to identify the best items (50) which could guarantee the maximum convergence on single scales (8), and the minimum redundancy between scales; c) Validation of the 8 scales' structure by a confirmatory factor analysis (fully achieved); d) Factor analysis for a second level factor resulting in a single factor identified as the questionnaire total score (Stress Score); d) Reliability analysis of the questionnaire total score and the single scale scores (at optimum level); e) Validation by external criteria of work related stress identified in the presence of personal violence episodes experienced by a group of health workers with different professional profiles and from two different hospitals in Rome. Our results show that the SPQR is a useful and sensitive tool for assessing the presence of emotional stress related problems identifiable in a work environment. The advantage of this questionnaire is that it allows for a multidimensional description of the different components of this problematic area besides its ability to quantify the overall stress level of those who have been administered

  19. Automatically assessing properties of dynamic cameras for camera selection and rapid deployment of video content analysis tasks in large-scale ad-hoc networks

    NASA Astrophysics Data System (ADS)

    den Hollander, Richard J. M.; Bouma, Henri; van Rest, Jeroen H. C.; ten Hove, Johan-Martijn; ter Haar, Frank B.; Burghouts, Gertjan J.

    2017-10-01

    Video analytics is essential for managing large quantities of raw data that are produced by video surveillance systems (VSS) for the prevention, repression and investigation of crime and terrorism. Analytics is highly sensitive to changes in the scene, and for changes in the optical chain so a VSS with analytics needs careful configuration and prompt maintenance to avoid false alarms. However, there is a trend from static VSS consisting of fixed CCTV cameras towards more dynamic VSS deployments over public/private multi-organization networks, consisting of a wider variety of visual sensors, including pan-tilt-zoom (PTZ) cameras, body-worn cameras and cameras on moving platforms. This trend will lead to more dynamic scenes and more frequent changes in the optical chain, creating structural problems for analytics. If these problems are not adequately addressed, analytics will not be able to continue to meet end users' developing needs. In this paper, we present a three-part solution for managing the performance of complex analytics deployments. The first part is a register containing meta data describing relevant properties of the optical chain, such as intrinsic and extrinsic calibration, and parameters of the scene such as lighting conditions or measures for scene complexity (e.g. number of people). A second part frequently assesses these parameters in the deployed VSS, stores changes in the register, and signals relevant changes in the setup to the VSS administrator. A third part uses the information in the register to dynamically configure analytics tasks based on VSS operator input. In order to support the feasibility of this solution, we give an overview of related state-of-the-art technologies for autocalibration (self-calibration), scene recognition and lighting estimation in relation to person detection. The presented solution allows for rapid and robust deployment of Video Content Analysis (VCA) tasks in large scale ad-hoc networks.

  20. The HOCS paradigm shift from disciplinary knowledge (LOCS)--to interdisciplinary evaluative, system thinking (HOCS): what should it take in science-technology-environment-society oriented courses, curricula and assessment?

    PubMed

    Zoller, U; Scholz, R W

    2004-01-01

    Given the current world state of affairs, striving for sustainability and the consequent paradigm shift: growth-to-sustainable development, correction-to-prevention and options selection-to-options generation: the corresponding paradigm shift in science-technology-environment-society (STES) education is unavoidable. Accordingly, the essence of the current reform in STES education, worldwide, is a purposed effort to develop students' higher-order cognitive skills (HOCS) capability; i.e., question-asking, critical system thinking, decision making and problem solving, at the expense of the "delivery" of lower-order cognitive skills (LOCS)-oriented knowledge. This means a paradigm shift from the contemporary prevalent LOCS algorithmic teaching to HOCS evaluative learning and HOCS-promoting courses, curricula, teaching strategies and assessment methodologies, leading, hopefully to evaluative thinking and transfer. Following the formulation of selected relevant axioms, major paradigm shift in STES research and education for sustainability have been identified. The consequent shift, in the STES context, from disciplinary to inter- and transdisciplinary learning, in science technology and environmental engineering education is discussed, followed by selected examples of successfully implemented HOCS-promoting courses, and assessment methodologies. It is argued, that transferable "HOCS learning" for sustainability can and should be done.

  1. Nursing home placement in the Donepezil and Memantine in Moderate to Severe Alzheimer's Disease (DOMINO-AD) trial: secondary and post-hoc analyses.

    PubMed

    Howard, Robert; McShane, Rupert; Lindesay, James; Ritchie, Craig; Baldwin, Ashley; Barber, Robert; Burns, Alistair; Dening, Tom; Findlay, David; Holmes, Clive; Jones, Robert; Jones, Roy; McKeith, Ian; Macharouthu, Ajay; O'Brien, John; Sheehan, Bart; Juszczak, Edmund; Katona, Cornelius; Hills, Robert; Knapp, Martin; Ballard, Clive; Brown, Richard G; Banerjee, Sube; Adams, Jessica; Johnson, Tony; Bentham, Peter; Phillips, Patrick P J

    2015-12-01

    Findings from observational studies have suggested a delay in nursing home placement with dementia drug treatment, but findings from a previous randomised trial of patients with mild-to-moderate Alzheimer's disease showed no effect. We investigated the effects of continuation or discontinuation of donepezil and starting of memantine on subsequent nursing home placement in patients with moderate-to-severe Alzheimer's disease. In the randomised, double-blind, placebo-controlled Donepezil and Memantine in Moderate to Severe Alzheimer's Disease (DOMINO-AD) trial, community-living patients with moderate-to-severe Alzheimer's disease (who had been prescribed donepezil continuously for at least 3 months at a dose of 10 mg for at least the previous 6 weeks and had a score of between 5 and 13 on the Standardised Mini-Mental State Examination) were recruited from 15 secondary care memory centres in England and Scotland and randomly allocated to continue donepezil 10 mg per day without memantine, discontinue donepezil without memantine, discontinue donepezil and start memantine 20 mg per day, or continue donepezil 10 mg per day and start memantine 20 mg per day, for 52 weeks. After 52 weeks, choice of treatment was left to participants and their physicians. Place of residence was recorded during the first 52 weeks of the trial and then every 26 weeks for a further 3 years. A secondary outcome of the trial, reported in this study, was nursing home placement: an irreversible move from independent accommodation to a residential caring facility. Analyses restricted to risk of placement in the first year of follow-up after the patients had completed the double-blind phase of the trial were post-hoc. The DOMINO-AD trial is registered with the ISRCTN Registry, number ISRCTN49545035. Between Feb 11, 2008, and March 5, 2010, 73 (25%) patients were randomly assigned to continue donepezil without memantine, 73 (25%) to discontinue donepezil without memantine, 76 (26%) to discontinue

  2. Valid randomization-based p-values for partially post hoc subgroup analyses.

    PubMed

    Lee, Joseph J; Rubin, Donald B

    2015-10-30

    By 'partially post-hoc' subgroup analyses, we mean analyses that compare existing data from a randomized experiment-from which a subgroup specification is derived-to new, subgroup-only experimental data. We describe a motivating example in which partially post hoc subgroup analyses instigated statistical debate about a medical device's efficacy. We clarify the source of such analyses' invalidity and then propose a randomization-based approach for generating valid posterior predictive p-values for such partially post hoc subgroups. Lastly, we investigate the approach's operating characteristics in a simple illustrative setting through a series of simulations, showing that it can have desirable properties under both null and alternative hypotheses. Copyright © 2015 John Wiley & Sons, Ltd.

  3. An evidence-based definition of lifelong premature ejaculation: report of the International Society for Sexual Medicine Ad Hoc Committee for the Definition of Premature Ejaculation.

    PubMed

    McMahon, Chris G; Althof, Stanley; Waldinger, Marcel D; Porst, Hartmut; Dean, John; Sharlip, Ira; Adaikan, P G; Becher, Edgardo; Broderick, Gregory A; Buvat, Jacques; Dabees, Khalid; Giraldi, Annamaria; Giuliano, François; Hellstrom, Wayne J G; Incrocci, Luca; Laan, Ellen; Meuleman, Eric; Perelman, Michael A; Rosen, Raymond; Rowland, David; Segraves, Robert

    2008-08-01

    To develop a contemporary, evidence-based definition of premature ejaculation (PE). There are several definitions of PE; the most commonly quoted, the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders - 4th Edition - Text Revision, and other definitions of PE, are all authority-based rather than evidence-based, and have no support from controlled clinical and/or epidemiological studies. Thus in August 2007, the International Society for Sexual Medicine (ISSM) appointed several international experts in PE to an Ad Hoc Committee for the Definition of PE. The committee met in Amsterdam in October 2007 to evaluate the strengths and weaknesses of current definitions of PE, to critically assess the evidence in support of the constructs of ejaculatory latency, ejaculatory control, sexual satisfaction and personal/interpersonal distress, and to propose a new evidence-based definition of PE. The Committee unanimously agreed that the constructs which are necessary to define PE are rapidity of ejaculation, perceived self-efficacy, and control and negative personal consequences from PE. The Committee proposed that lifelong PE be defined as a male sexual dysfunction characterized by ejaculation which always or nearly always occurs before or within about one minute of vaginal penetration, and the inability to delay ejaculation on all or nearly all vaginal penetrations, and negative personal consequences, such as distress, bother, frustration and/or the avoidance of sexual intimacy. This definition is limited to men with lifelong PE who engage in vaginal intercourse. The panel concluded that there are insufficient published objective data to propose an evidence-based definition of acquired PE. The ISSM definition of lifelong PE represents the first evidence-based definition of PE. This definition will hopefully lead to the development of new tools and patient-reported outcome measures for diagnosing and assessing the efficacy of treatment

  4. Post Hoc Analyses of the Effect of Crisaborole Topical Ointment, 2% on Atopic Dermatitis: Associated Pruritus from Phase 1 and 2 Clinical Studies.

    PubMed

    Draelos, Zoe Diana; Stein Gold, Linda F; Murrell, Dedee F; Hughes, Matilda H; Zane, Lee T

    2016-02-01

    Two post hoc analyses assessed the antipruritic activity of crisaborole topical ointment, 2% (crisaborole; Anacor Pharmaceuticals, Inc., Palo Alto, CA), a first-in-class boron-based phosphodiesterase-4 inhibitor in development for treatment of mild to moderate atopic dermatitis (AD). Two pooled analyses included data from 4 studies evaluating crisaborole in AD (study 1, phase 1b, systemic exposure, safety, and pharmacokinetics [PK] under maximal-use conditions in children and adolescents; study 2, phase 2a, safety and PK in adolescents; study 3, phase 2a, efficacy and safety in adults; study 4, phase 2, efficacy and safety in adolescents). Pooled data from studies 1 and 2 included whole body assessments; studies 3 and 4 included target lesion assessments. Pruritus severity was evaluated using a 4-point rating scale (0=none to 3=severe). Efficacy assessments included percent change from baseline in pruritus severity scores at days 8 (first pooled assessment), 15, 22, and 29 (whole body assessments) or days 15 (first pooled assessment), 22, and 29 (target lesions). Paired t-tests comparing change from baseline against zero were used to calculate P values. Categorical shifts in pruritus severity were also assessed (no to mild pruritus, 0-1.5; moderate to severe pruritus, 2-3). In the pooled analysis of studies 1 and 2 (N=57), the percent change from baseline in pruritus severity scores were 63.0% and 64.9% at days 8 and 29, respectively (P<0.001 for each). Similar results were observed in the pooled analysis of studies 3 and 4 (N=67). In both analyses, most patients had mild to no pruritus from the first time point assessed through the remainder of treatment. Treatment with crisaborole topical ointment, 2% resulted in statistically significant reductions in pruritus severity at the first time point evaluated in both analyses. These findings provide preliminary evidence of the antipruritic activity of crisaborole topical ointment, 2%.

  5. Ad Hoc Network Architecture for Multi-Media Networks

    DTIC Science & Technology

    2007-12-01

    sensor network . Video traffic is modeled and simulations are performed via the use of the Sun Small Programmable Object Technology (Sun SPOT) Java...characteristics of video traffic must be studied and understood. This thesis focuses on evaluating the possibility of routing video images over a wireless

  6. Homoclinic chaos in axisymmetric Bianchi-IX cosmological models with an ad hoc quantum potential

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Correa, G. C.; Stuchi, T. J.; Joras, S. E.

    2010-04-15

    In this work we study the dynamics of the axisymmetric Bianchi-IX cosmological model with a term of quantum potential added. As it is well known, this class of Bianchi-IX models is homogeneous and anisotropic with two scale factors, A(t) and B(t), derived from the solution of Einstein's equation for general relativity. The model we use in this work has a cosmological constant and the matter content is dust. To this model we add a quantum-inspired potential that is intended to represent short-range effects due to the general relativistic behavior of matter in small scales and play the role of amore » repulsive force near the singularity. We find that this potential restricts the dynamics of the model to positive values of A(t) and B(t) and alters some qualitative and quantitative characteristics of the dynamics studied previously by several authors. We make a complete analysis of the phase space of the model finding critical points, periodic orbits, stable/unstable manifolds using numerical techniques such as Poincare section, numerical continuation of orbits, and numerical globalization of invariant manifolds. We compare the classical and the quantum models. Our main result is the existence of homoclinic crossings of the stable and unstable manifolds in the physically meaningful region of the phase space [where both A(t) and B(t) are positive], indicating chaotic escape to inflation and bouncing near the singularity.« less

  7. An Experimental Study of Men's and Women's Personal Ads.

    PubMed

    Strassberg, Donald S; English, Brittany L

    2015-11-01

    Personal ads have long served as a potentially rich source of information for social scientists regarding what women and men appear to be looking for in a partner and what they believe potential partners are looking for in them. Almost every study of this type has content analyzed existing personal ads in print media or, more recently, on the Internet. Many of the limits of this research approach were addressed in a study by Strassberg and Holty (2003) utilizing an experimental research design. Contrary to theory, prior research, and prediction, the most popular female seeking male (FSM) ad in that study was one in which the woman described herself as "financially independent, successful [and] ambitious," producing over 50 % more responses than the next most popular ad, describing the writer as "very attractive and slim." The present study replicated the Strassberg and Holty methodology, placing the same fictitious MSF and FSM personal ads using far more accessible Internet personal ad sites. Contrary to the previous finding, but consistent with evolutionary theories and social psychological experiments (e.g., Townsend & Wasserman, 1998), ads that presented the woman as attractive and the man as financially successful elicited the most interest.

  8. Ad-Hoc Implicature in Preschool Children

    ERIC Educational Resources Information Center

    Stiller, Alex J.; Goodman, Noah D.; Frank, Michael C.

    2015-01-01

    If a speaker tells us that "some guests were late to the party," we typically infer that not all were. Implicatures, in which an ambiguous statement ("some and possibly all") is strengthened pragmatically (to "some and not all"), are a paradigm case of pragmatic reasoning. Inferences of this sort are difficult for…

  9. Rotigotine transdermal system and evaluation of pain in patients with Parkinson's disease: a post hoc analysis of the RECOVER study.

    PubMed

    Kassubek, Jan; Chaudhuri, Kallol Ray; Zesiewicz, Theresa; Surmann, Erwin; Boroojerdi, Babak; Moran, Kimberly; Ghys, Liesbet; Trenkwalder, Claudia

    2014-03-06

    Pain is a troublesome non-motor symptom of Parkinson's disease (PD). The RECOVER (Randomized Evaluation of the 24-hour Coverage: Efficacy of Rotigotine; Clintrials.gov: NCT00474058) study demonstrated significant improvements in early-morning motor function (UPDRS III) and sleep disturbances (PDSS-2) with rotigotine transdermal system. Improvements were also reported on a Likert pain scale (measuring any type of pain). This post hoc analysis of RECOVER further evaluates the effect of rotigotine on pain, and whether improvements in pain may be attributable to benefits in motor function or sleep disturbance. PD patients with unsatisfactory early-morning motor impairment were randomized to optimal-dose (up to 16 mg/24 h) rotigotine or placebo, maintained for 4 weeks. Pain was assessed in the early-morning using an 11-point Likert pain scale (rated average severity of pain (of any type) over the preceding 12 hours from 0 [no pain] to 10 [worst pain ever experienced]). Post hoc analyses for patients reporting 'any' pain (pain score ≥1) at baseline, and subgroups reporting 'mild' (score 1-3), and 'moderate-to-severe' pain (score ≥4) were performed. Likert pain scale change from baseline in rotigotine-treated patients was further analyzed based on a UPDRS III/PDSS-2 responder analysis (a responder defined as showing a ≥30% reduction in early morning UPDRS III total score or PDSS-2 total score). As post hoc analyses, all p values presented are exploratory. Of 267 patients with Likert pain data (178 rotigotine, 89 placebo), 187 (70%) reported 'any' pain; of these 87 (33%) reported 'mild', and 100 (37%) 'moderate-to-severe' pain. Change from baseline pain scores decreased with rotigotine compared with placebo in patients with 'any' pain (-0.88 [95% CI: -1.56, -0.19], p = 0.013), and in the subgroup with 'moderate-to-severe' pain (-1.38 [-2.44, -0.31], p = 0.012). UPDRS III or PDSS-2 responders showed greater improvement in pain than non-responders. The results

  10. [Implementation of interdisciplinary multimodal pain therapy according to OPS 8‑918 : Recommendations of the ad hoc commission for interdisciplinary multimodal pain therapy of the German Pain Association].

    PubMed

    Arnold, B; Böger, A; Brinkschmidt, T; Casser, H-R; Irnich, D; Kaiser, U; Klimczyk, K; Lutz, J; Pfingsten, M; Sabatowski, R; Schiltenwolf, M; Söllner, W

    2018-02-01

    With the implementation of the German diagnosis-related groups (DRG) reimbursement system in hospitals, interdisciplinary multimodal pain therapy was incorporated into the associated catalogue of procedures (OPS 8‑918). Yet, the presented criteria describing the procedure of interdisciplinary multimodal pain therapy are neither precise nor unambiguous. This has led to discrepancies in the interpretation regarding the handling of the procedure-making it difficult for medical services of health insurance companies to evaluate the accordance between the delivered therapy and the required criteria. Since the number of pain units has increased in recent years, the number of examinations by the medical service of health insurance companies has increased. This article, published by the ad hoc commission for interdisciplinary multimodal pain therapy of the German Pain Association, provides specific recommendations for correct implementation of interdisciplinary multimodal pain therapy in routine care. The aim is to achieve a maximum level of accordance between health care providers and the requirements of the medical examiners from health insurance companies. More extensive criteria regarding interdisciplinary multimodal pain treatment in an in-patient setting, especially for patients with chronic and complex pain, are obviously needed. Thus, the authors further discuss specific aspects towards further development of the OPS-code. However, the application of the OPS-code still leaves room regarding treatment intensity and process quality. Therefore, the delivery of pain management in sufficient quantity and quality still remains the responsibility of each health care provider.

  11. An evidence-based definition of lifelong premature ejaculation: report of the International Society for Sexual Medicine (ISSM) ad hoc committee for the definition of premature ejaculation.

    PubMed

    McMahon, Chris G; Althof, Stanley E; Waldinger, Marcel D; Porst, Hartmut; Dean, John; Sharlip, Ira D; Adaikan, P G; Becher, Edgardo; Broderick, Gregory A; Buvat, Jacques; Dabees, Khalid; Giraldi, Annamaria; Giuliano, François; Hellstrom, Wayne J G; Incrocci, Luca; Laan, Ellen; Meuleman, Eric; Perelman, Michael A; Rosen, Raymond C; Rowland, David L; Segraves, Robert

    2008-07-01

    The medical literature contains several definitions of premature ejaculation (PE). The most commonly quoted definition, the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition-Text Revision, and other definitions of PE are all authority based rather than evidence based, and have no support from controlled clinical and/or epidemiological studies. The aim of this article is to develop a contemporary, evidence-based definition of PE. In August 2007, the International Society for Sexual Medicine (ISSM) appointed several international experts in PE to an Ad Hoc Committee for the Definition of Premature Ejaculation. The committee met in Amsterdam in October 2007 to evaluate the strengths and weaknesses of current definitions of PE, to critique the evidence in support of the constructs of ejaculatory latency, ejaculatory control, sexual satisfaction, and personal/interpersonal distress, and to propose a new evidence-based definition of PE. The committee unanimously agreed that the constructs that are necessary to define PE are rapidity of ejaculation, perceived self-efficacy and control, and negative personal consequences from PE. The committee proposed that lifelong PE be defined as ". . . a male sexual dysfunction characterized by ejaculation which always or nearly always occurs prior to or within about one minute of vaginal penetration, and the inability to delay ejaculation on all or nearly all vaginal penetrations, and negative personal consequences, such as distress, bother, frustration and/or the avoidance of sexual intimacy." This definition is limited to men with lifelong PE who engage in vaginal intercourse. The panel concluded that there are insufficient published objective data to propose an evidence-based definition of acquired PE. The ISSM definition of lifelong PE represents the first evidence-based definition of PE. This definition will hopefully lead to the development of new tools and Patient Reported

  12. Report of the AD HOC Committee on Patent Documentation.

    ERIC Educational Resources Information Center

    Urbach, Peter; And Others

    The Committee was established in September 1967 to study and make recommendations on Recommendation XXIX and XXX of the Report of the President's Commission on the Patent System. Based on interviews with Patent Office officials, patent examiners and classifiers and a review of Patent Office studies and documents, the Committee concluded that the…

  13. Segmented strings in AdS 3

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Callebaut, Nele; Gubser, Steven S.; Samberg, Andreas

    We study segmented strings in flat space and in AdS 3. In flat space, these well known classical motions describe strings which at any instant of time are piecewise linear. In AdS 3, the worldsheet is composed of faces each of which is a region bounded by null geodesics in an AdS 2 subspace of AdS 3. The time evolution can be described by specifying the null geodesic motion of kinks in the string at which two segments are joined. The outcome of collisions of kinks on the worldsheet can be worked out essentially using considerations of causality. We studymore » several examples of closed segmented strings in AdS 3 and find an unexpected quasi-periodic behavior. Here, we also work out a WKB analysis of quantum states of yo-yo strings in AdS 5 and find a logarithmic term reminiscent of the logarithmic twist of string states on the leading Regge trajectory.« less

  14. Segmented strings in AdS 3

    DOE PAGES

    Callebaut, Nele; Gubser, Steven S.; Samberg, Andreas; ...

    2015-11-17

    We study segmented strings in flat space and in AdS 3. In flat space, these well known classical motions describe strings which at any instant of time are piecewise linear. In AdS 3, the worldsheet is composed of faces each of which is a region bounded by null geodesics in an AdS 2 subspace of AdS 3. The time evolution can be described by specifying the null geodesic motion of kinks in the string at which two segments are joined. The outcome of collisions of kinks on the worldsheet can be worked out essentially using considerations of causality. We studymore » several examples of closed segmented strings in AdS 3 and find an unexpected quasi-periodic behavior. Here, we also work out a WKB analysis of quantum states of yo-yo strings in AdS 5 and find a logarithmic term reminiscent of the logarithmic twist of string states on the leading Regge trajectory.« less

  15. Rotigotine transdermal system and evaluation of pain in patients with Parkinson’s disease: a post hoc analysis of the RECOVER study

    PubMed Central

    2014-01-01

    Background Pain is a troublesome non-motor symptom of Parkinson’s disease (PD). The RECOVER (Randomized Evaluation of the 24-hour Coverage: Efficacy of Rotigotine; Clintrials.gov: NCT00474058) study demonstrated significant improvements in early-morning motor function (UPDRS III) and sleep disturbances (PDSS-2) with rotigotine transdermal system. Improvements were also reported on a Likert pain scale (measuring any type of pain). This post hoc analysis of RECOVER further evaluates the effect of rotigotine on pain, and whether improvements in pain may be attributable to benefits in motor function or sleep disturbance. Methods PD patients with unsatisfactory early-morning motor impairment were randomized to optimal-dose (up to 16 mg/24 h) rotigotine or placebo, maintained for 4 weeks. Pain was assessed in the early-morning using an 11-point Likert pain scale (rated average severity of pain (of any type) over the preceding 12 hours from 0 [no pain] to 10 [worst pain ever experienced]). Post hoc analyses for patients reporting ‘any’ pain (pain score ≥1) at baseline, and subgroups reporting ‘mild’ (score 1–3), and ‘moderate-to-severe’ pain (score ≥4) were performed. Likert pain scale change from baseline in rotigotine-treated patients was further analyzed based on a UPDRS III/PDSS-2 responder analysis (a responder defined as showing a ≥30% reduction in early morning UPDRS III total score or PDSS-2 total score). As post hoc analyses, all p values presented are exploratory. Results Of 267 patients with Likert pain data (178 rotigotine, 89 placebo), 187 (70%) reported ‘any’ pain; of these 87 (33%) reported ‘mild’, and 100 (37%) ‘moderate-to-severe’ pain. Change from baseline pain scores decreased with rotigotine compared with placebo in patients with ‘any’ pain (-0.88 [95% CI: -1.56, -0.19], p = 0.013), and in the subgroup with ‘moderate-to-severe’ pain (-1.38 [-2.44, -0.31], p = 0.012). UPDRS III or PDSS-2 responders

  16. Clinically inappropriate post hoc exclusion of study participants from test accuracy calculations: the ROMA score, an example from a recent NICE diagnostic assessment.

    PubMed

    Lang, Shona; Armstrong, Nigel; Deshpande, Sohan; Ramaekers, Bram; Grimm, Sabine; de Kock, Shelley; Kleijnen, Jos; Westwood, Marie

    2018-01-01

    Objective To explore how the definition of the target condition and post hoc exclusion of participants can limit the usefulness of diagnostic accuracy studies. Methods We used data from a systematic review, conducted for a NICE diagnostic assessment of risk scores to inform secondary care decisions about specialist referral for women with suspected ovarian cancer, to explore how the definition of the target condition and post hoc exclusion of participants can limit the usefulness of diagnostic accuracy studies to inform clinical practice. Results Fourteen of the studies evaluated the ROMA score, nine used Abbott ARCHITECT tumour marker assays, five used Roche Elecsys. The summary sensitivity estimate (Abbott ARCHITECT) was highest, 95.1% (95% CI: 92.4 to 97.1%), where analyses excluded participants with borderline tumours or malignancies other than epithelial ovarian cancer and lowest, 75.0% (95% CI: 60.4 to 86.4%), where all participants were included. Results were similar for Roche Elecsys tumour marker assays. Although the number of patients involved was small, data from studies that reported diagnostic accuracy for both the whole study population and with post hoc exclusion of those with borderline or non-epithelial malignancies suggested that patients with borderline or malignancies other than epithelial ovarian cancer accounts for between 50 and 85% of false-negative ROMA scores. Conclusions Our results illustrate the potential consequences of inappropriate population selection in diagnostic studies; women with non-epithelial ovarian cancers or non-ovarian primaries, and those borderline tumours may be disproportionately represented among those with false negative, 'low risk' ROMA scores. These observations highlight the importance of giving careful consideration to how the target condition has been defined when assessing whether the diagnostic accuracy estimates reported in clinical studies will translate into clinical utility in real-world settings.

  17. Level of literacy and dementia: A secondary post-hoc analysis from North-West India.

    PubMed

    Raina, Sunil Kumar; Chander, Vishav; Kumar, Dinesh; Raina, Sujeet; Bhardwaj, Ashok

    2014-10-01

    A relation between literacy and dementia has been studied in past and an association has been documented. This is in spite of some studies pointing to the contrary. The current study was aimed at investigating the influence of level of literacy on dementia in a sample stratified by geography (Migrant, Urban, Rural and Tribal areas of sub-Himalayan state of Himachal Pradesh, India). The study was based on post-hoc analysis of data obtained from a study conducted on elderly population (60 years and above) from selected geographical areas (Migrant, Urban, Rural and Tribal) of Himachal Pradesh state in North-west India. Analysis of variance revealed an effect of education on cognitive scores [F = 2.823, P =0.01], however, post-hoc Tukey's HSD test did not reveal any significant pairwise comparisons. The possibility that education effects dementia needs further evaluation, more so in Indian context.

  18. A Computational Method to Determine Glucose Infusion Rates for Isoglycemic Intravenous Glucose Infusion Study.

    PubMed

    Choi, Karam; Lee, Jung Chan; Oh, Tae Jung; Kim, Myeungseon; Kim, Hee Chan; Cho, Young Min; Kim, Sungwan

    2016-01-01

    The results of the isoglycemic intravenous glucose infusion (IIGI) study need to mimic the dynamic glucose profiles during the oral glucose tolerance test (OGTT) to accurately calculate the incretin effect. The glucose infusion rates during IIGI studies have historically been determined by experienced research personnel using the manual ad-hoc method. In this study, a computational method was developed to automatically determine the infusion rates for IIGI study based on a glucose-dynamics model. To evaluate the computational method, 18 subjects with normal glucose tolerance underwent a 75 g OGTT. One-week later, Group 1 (n = 9) and Group 2 (n = 9) underwent IIGI studies using the ad-hoc method and the computational method, respectively. Both methods were evaluated using correlation coefficient, mean absolute relative difference (MARD), and root mean square error (RMSE) between the glucose profiles from the OGTT and the IIGI study. The computational method exhibited significantly higher correlation (0.95 ± 0.03 versus 0.86 ± 0.10, P = 0.019), lower MARD (8.72 ± 1.83% versus 13.11 ± 3.66%, P = 0.002), and lower RMSE (10.33 ± 1.99 mg/dL versus 16.84 ± 4.43 mg/dL, P = 0.002) than the ad-hoc method. The computational method can facilitate IIGI study, and enhance its accuracy and stability. Using this computational method, a high-quality IIGI study can be accomplished without the need for experienced personnel.

  19. [Health evaluation of trichloroethylene in indoor air : communication from the German ad-hoc working group on indoor guidelines of the Indoor Air Hygiene Committee and of the states' supreme health authorities].

    PubMed

    2015-07-01

    In the European Hazardous Substances Regulation No 1272/2008 trichloroethylene has been classified as a probable human carcinogen and a suspected mutagen. According to several Committees (German Committee on Hazardous Substances, European Scientific Committee on Occupational Exposure Limits, European Chemicals Agency´s Committee for Risk Assessment (ECHA-RAC)) concentrations of trichloroethylene cytotoxic to renal tubuli may increase the risk to develop renal cancer. At non-cytotoxic concentrations of trichloroethylene a much lower cancer risk may be assumed. Therefore, evaluating the cancer risk to the public following inhalation of trichloroethylene ECHA-RAC has assumed a sublinear exposure-response relationship for carcinogenicity of trichloroethylene. Specifically, ECHA-RAC assessed a cancer risk of 6.4 × 10(- 5) (mg/m(3))(- 1) following life time exposure to trichloroethylene below a NOAEC for renal cytotoxicity of 6 mg trichloroethylene/m(3). Further evaluation yields a life-time risk of 10(- 6) corresponding to 0.02 mg trichloroethylene/m(3). This concentration is well above the reference (e.g. background) concentration of trichloroethylene in indoor air. Consequently the Ad-hoc Working Group on Indoor Guidelines recommends 0.02 mg trichloroethylene/m(3) as a risk-related guideline for indoor air. Measures to reduce exposure are considered inappropriate at concentrations below this guideline.

  20. Studying the complex spectral line profiles in the spectra of hot emission stars and quasars .

    NASA Astrophysics Data System (ADS)

    Danezis, E.; Lyratzi, E.; Antoniou, A.; Popović, L. Č.; Dimitrijević, M. S.

    Some Hot Emission Stars and AGNs present peculiar spectral line profiles which are due to DACs and SACs phenomena. The origin and the mechanisms which are responsible for the creation of DACs/SACs is an important problem that has been studied by many researchers. This paper is a review of our efforts to study the origin and the mechanisms of these phenomena. At first we present a theoretic ad hoc picture for the structure of the plasma that surrounds the specific category of hot emission stars that present DACs or SACs. Then we present the mathematical model that we constructed, which is based on the properties of the above ad hoc theoretical structure. Finally, we present some results from our statistical studies that prove the consistency of our model with the classical physical theory.

  1. Distribution of Information in Ad Hoc Networks

    DTIC Science & Technology

    2007-09-01

    2.4. MACA Protocol...................................20 Figure 2.5. Route discovery in AODV (From [32]).............28 Figure 2.6. Creation of a...19 Figure 2.3. Exposed terminal Problem (From [20]) (3) MACA and MACAW Protocols. One of the first protocols conceived for wireless local area...networks is MACA [21] (Multiple Accesses with Collision Avoidance). The transmitter sends a small packet, or RTS (Request To Send), which has little

  2. Life Cycles of Ad Hoc Task Groups

    DTIC Science & Technology

    1983-10-01

    Rick’s Cafe after work. . 25 Alexandra: You have connections? 26 Ken: Yes! ൣ Alexandra: You can be the industrial spy! (Pause) We don’t really need...with franchising --he could do a whole business strictly dealing with spare parts. We have to describe these packages and describe how to... (words

  3. Distributed Trust Evaluation in Ad-Hoc Networks

    DTIC Science & Technology

    2004-01-01

    of money that the issuer will pay to anyone who is misled because of the certificate. Being misled means falsely authenticating the certified entity...Alice to Bob. This is the minimum amount of money for which Alice is insured in the case of her being misled by Bob’s key. Note that if all edges are...confidence gets to vote first. Moreover, some paths are pruned which means that fewer messages are exchanged, thus saving bandwidth, but also some of the

  4. Swift Trust in Distributed Ad Hoc Teams

    DTIC Science & Technology

    2007-10-04

    individus sont perçus. Et les abus de confiance commis pendant la mission ont nui temporairement à la réputation de leurs auteurs , mais ils n’ont...of theory and research argue that trust may emerge in teams even when the development of conventional person-based trust is challenged. 1.3.1 Swift...good deal of theory (and some research) espouses the importance of “swift trust” in environments where conventional trust would otherwise be

  5. Realtime multiprocessor for mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Jungeblut, T.; Grünewald, M.; Porrmann, M.; Rückert, U.

    2008-05-01

    This paper introduces a real-time Multiprocessor System-On-Chip (MPSoC) for low power wireless applications. The multiprocessor is based on eight 32bit RISC processors that are connected via an Network-On-Chip (NoC). The NoC follows a novel approach with guaranteed bandwidth to the application that meets hard realtime requirements. At a clock frequency of 100 MHz the total power consumption of the MPSoC that has been fabricated in 180 nm UMC standard cell technology is 772 mW.

  6. Sensor Sharing in Mobile Ad-Hoc Networks

    ERIC Educational Resources Information Center

    Mitra, Pramita

    2013-01-01

    Today's modern mobile devices (such as smartphones and tablets) present great potential for growth of many novel, powerful, but also highly demanding applications. However, most mobile devices/users operate in isolation from one another, i.e., they are not aware of the presence of other devices in their proximity. There are numerous situations…

  7. Some new ideas for the study of the complex spectral line profiles of hot emission stars and quasars

    NASA Astrophysics Data System (ADS)

    Danezis, E.

    2013-01-01

    Some Hot Emission Stars and AGNs present peculiar spectral line profiles which are due to DACs and SACs phenomena. The origin and the mechanisms which are responsible for the creation of DACs/SACs is an important problem that has been studied by many researchers. This paper is a review of our efforts to study the origin and the mechanisms of these phenomena. At first we present a theoretic ad hoc picture for the structure of the plasma that surrounds the specific category of hot emission stars that present DACs or SACs. Then we present the mathematical model that we constructed, which is based on the properties of the above ad hoc theoretical structure. Finally, we present some results from our statistical studies that prove the consistency of our model with the classical physical theory.

  8. Research of ad hoc network based on SINCGARS network

    NASA Astrophysics Data System (ADS)

    Nie, Hao; Cai, Xiaoxia; Chen, Hong; Chen, Jian; Weng, Pengfei

    2016-03-01

    In today's world, science and technology make a spurt of progress, so society has entered the era of information technology, network. Only the comprehensive use of electronic warfare and network warfare means can we maximize their access to information and maintain the information superiority. Combined with the specific combat mission and operational requirements, the research design and construction in accordance with the actual military which are Suitable for the future of information technology needs of the tactical Adhoc network, tactical internet, will greatly improve the operational efficiency of the command of the army. Through the study of the network of the U.S. military SINCGARS network, it can explore the routing protocol and mobile model, to provide a reference for the research of our army network.

  9. Anti-Vascular Endothelial Growth Factor Comparative Effectiveness Trial for Diabetic Macular Edema: Additional Efficacy Post Hoc Analyses of a Randomized Clinical Trial.

    PubMed

    Jampol, Lee M; Glassman, Adam R; Bressler, Neil M; Wells, John A; Ayala, Allison R

    2016-12-01

    Post hoc analyses from the Diabetic Retinopathy Clinical Research Network randomized clinical trial comparing aflibercept, bevacizumab, and ranibizumab for diabetic macular edema (DME) might influence interpretation of study results. To provide additional outcomes comparing 3 anti-vascular endothelial growth factor (VEGF) agents for DME. Post hoc analyses performed from May 3, 2016, to June 21, 2016, of a randomized clinical trial performed from August 22, 2012, to September 23, 2015, of 660 participants comparing 3 anti-VEGF treatments in eyes with center-involved DME causing vision impairment. Randomization to intravitreous aflibercept (2.0 mg), bevacizumab (1.25 mg), or ranibizumab (0.3 mg) administered up to monthly based on a structured retreatment regimen. Focal/grid laser treatment was added after 6 months for the treatment of persistent DME. Change in visual acuity (VA) area under the curve and change in central subfield thickness (CST) within subgroups based on whether an eye received laser treatment for DME during the study. Post hoc analyses were performed for 660 participants (mean [SD] age, 61 [10] years; 47% female, 65% white, 16% black or African American, 16% Hispanic, and 3% other). For eyes with an initial VA of 20/50 or worse, VA improvement was greater with aflibercept than the other agents at 1 year but superior only to bevacizumab at 2 years. Mean (SD) letter change in VA over 2 years (area under curve) was greater with aflibercept (+17.1 [9.7]) than with bevacizumab (+12.1 [9.4]; 95% CI, +1.6 to +7.3; P < .001) or ranibizumab (+13.6 [8.5]; 95% CI, +0.7 to +6.0; P = .009). When VA was 20/50 or worse at baseline, bevacizumab reduced CST less than the other agents at 1 year, but at 2 years the differences had diminished. In subgroups stratified by baseline VA, anti-VEGF agent, and whether focal/grid laser treatment was performed for DME, the only participants to have a substantial reduction in mean CST between 1 and 2 years were those

  10. Two Virasoro symmetries in stringy warped AdS 3

    DOE PAGES

    Compere, Geoffrey; Guica, Monica; Rodriguez, Maria J.

    2014-12-02

    We study three-dimensional consistent truncations of type IIB supergravity which admit warped AdS 3 solutions. These theories contain subsectors that have no bulk dynamics. We show that the symplectic form for these theories, when restricted to the non-dynamical subsectors, equals the symplectic form for pure Einstein gravity in AdS 3. Consequently, for each consistent choice of boundary conditions in AdS 3, we can define a consistent phase space in warped AdS 3 with identical conserved charges. This way, we easily obtain a Virasoro × Virasoro asymptotic symmetry algebra in warped AdS 3; two different types of Virasoro × Kač-Moody symmetriesmore » are also consistent alternatives. Next, we study the phase space of these theories when propagating modes are included. We show that, as long as one can define a conserved symplectic form without introducing instabilities, the Virasoro × Virasoro asymptotic symmetries can be extended to the entire (linearised) phase space. In conclusion, this implies that, at least at semi-classical level, consistent theories of gravity in warped AdS 3 are described by a two-dimensional conformal field theory, as long as stability is not an issue.« less

  11. Two Virasoro symmetries in stringy warped AdS 3

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Compere, Geoffrey; Guica, Monica; Rodriguez, Maria J.

    We study three-dimensional consistent truncations of type IIB supergravity which admit warped AdS 3 solutions. These theories contain subsectors that have no bulk dynamics. We show that the symplectic form for these theories, when restricted to the non-dynamical subsectors, equals the symplectic form for pure Einstein gravity in AdS 3. Consequently, for each consistent choice of boundary conditions in AdS 3, we can define a consistent phase space in warped AdS 3 with identical conserved charges. This way, we easily obtain a Virasoro × Virasoro asymptotic symmetry algebra in warped AdS 3; two different types of Virasoro × Kač-Moody symmetriesmore » are also consistent alternatives. Next, we study the phase space of these theories when propagating modes are included. We show that, as long as one can define a conserved symplectic form without introducing instabilities, the Virasoro × Virasoro asymptotic symmetries can be extended to the entire (linearised) phase space. In conclusion, this implies that, at least at semi-classical level, consistent theories of gravity in warped AdS 3 are described by a two-dimensional conformal field theory, as long as stability is not an issue.« less

  12. Ultra-Wideband Impulse Radio for Tactical Ad-Hoc Military Communications

    DTIC Science & Technology

    2010-09-02

    Synchronization, Channel Estimation, and Detection for DS - CDMA Impulse-Radio Systems,” IEEE Transactions on Wireless Communications, vol. 4, no. 6, pp...desired user. Complex matrix operations required by other techniques found in the CDMA literature are not required in our suppression process...domain while a frequency-domain procedure for synchronization is studied in [52]. 5 In the CDMA literature, near-far resistant synchronization is studied

  13. The choice of product indicators in latent variable interaction models: post hoc analyses.

    PubMed

    Foldnes, Njål; Hagtvet, Knut Arne

    2014-09-01

    The unconstrained product indicator (PI) approach is a simple and popular approach for modeling nonlinear effects among latent variables. This approach leaves the practitioner to choose the PIs to be included in the model, introducing arbitrariness into the modeling. In contrast to previous Monte Carlo studies, we evaluated the PI approach by 3 post hoc analyses applied to a real-world case adopted from a research effort in social psychology. The measurement design applied 3 and 4 indicators for the 2 latent 1st-order variables, leaving the researcher with a choice among more than 4,000 possible PI configurations. Sixty so-called matched-pair configurations that have been recommended in previous literature are of special interest. In the 1st post hoc analysis we estimated the interaction effect for all PI configurations, keeping the real-world sample fixed. The estimated interaction effect was substantially affected by the choice of PIs, also across matched-pair configurations. Subsequently, a post hoc Monte Carlo study was conducted, with varying sample sizes and data distributions. Convergence, bias, Type I error and power of the interaction test were investigated for each matched-pair configuration and the all-pairs configuration. Variation in estimates across matched-pair configurations for a typical sample was substantial. The choice of specific configuration significantly affected convergence and the interaction test's outcome. The all-pairs configuration performed overall better than the matched-pair configurations. A further advantage of the all-pairs over the matched-pairs approach is its unambiguity. The final study evaluates the all-pairs configuration for small sample sizes and compares it to the non-PI approach of latent moderated structural equations. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  14. Phases of global AdS black holes

    NASA Astrophysics Data System (ADS)

    Basu, Pallab; Krishnan, Chethan; Subramanian, P. N. Bala

    2016-06-01

    We study the phases of gravity coupled to a charged scalar and gauge field in an asymptotically Anti-de Sitter spacetime ( AdS 4) in the grand canonical ensemble. For the conformally coupled scalar, an intricate phase diagram is charted out between the four relevant solutions: global AdS, boson star, Reissner-Nordstrom black hole and the hairy black hole. The nature of the phase diagram undergoes qualitative changes as the charge of the scalar is changed, which we discuss. We also discuss the new features that arise in the extremal limit.

  15. Gauge boson exchange in AdS d+1

    NASA Astrophysics Data System (ADS)

    D'Hoker, Eric; Freedman, Daniel Z.

    1999-04-01

    We study the amplitude for exchange of massless gauge bosons between pairs of massive scalar fields in anti-de Sitter space. In the AdS/CFT correspondence this amplitude describes the contribution of conserved flavor symmetry currents to 4-point functions of scalar operators in the boundary conformal theory. A concise, covariant, Y2K compatible derivation of the gauge boson propagator in AdS d + 1 is given. Techniques are developed to calculate the two bulk integrals over AdS space leading to explicit expressions or convenient, simple integral representations for the amplitude. The amplitude contains leading power and sub-leading logarithmic singularities in the gauge boson channel and leading logarithms in the crossed channel. The new methods of this paper are expected to have other applications in the study of the Maldacena conjecture.

  16. Toward a Comprehensive Framework of Study Abroad Intentions and Behaviors

    ERIC Educational Resources Information Center

    Goel, Lakshmi; de Jong, Pieter; Schnusenberg, Oliver

    2010-01-01

    Increased activity by U.S. students to study abroad has invited several studies that have investigated the reasons for U.S. students to study abroad. Literature in the context of study abroad choices has been fragmented, with each study presenting an ad-hoc set of factors the author/s deem as important or that have been shown to be important in…

  17. Recovery in bipolar depression: Post-hoc analysis of a placebo-controlled lurasidone trial followed by a long-term continuation study.

    PubMed

    Loebel, Antony; Siu, Cynthia; Rajagopalan, Krithika; Pikalov, Andrei; Cucchiaro, Josephine; Ketter, Terence A

    2015-11-01

    In this post-hoc analysis, rates of remission and recovery were evaluated in patients with bipolar depression treated with lurasidone. Outpatients meeting DSM-IV-TR criteria for bipolar I depression, were randomized to 6 weeks of once-daily, double-blind treatment with lurasidone 20-60mg, lurasidone 80-120mg or placebo, followed by a 6-month, open-label, flexible-dose, lurasidone continuation study. Recovery was defined as meeting criteria for combined symptomatic remission (Montgomery-Asberg Depression Rating Scale total score ≤12) and functional remission (all Sheehan Disability Scale domain scores ≤3) sustained for at least 3 months in the 6-month continuation study. A significantly higher proportion of lurasidone-treated patients met criteria for combined symptomatic remission and functional remission (33.3%, 91/273) compared to the placebo group (21.0%, 30/143, p<0.05, NNT=9) at the 6-week study endpoint. In the 6-month continuation study, the proportion of lurasidone-treated patients achieving sustained recovery was 60.7% (85/140) and 44.9% (31/69), for patients who continued lurasidone treatment and who switched from placebo to lurasidone, respectively. The definition of recovery used has not been previously validated and the analysis was post hoc. Lack of a control group in the continuation study limits data interpretation. Recovery in patients with bipolar depression was assessed based on rates of combined symptomatic and functional remission sustained over time. A majority of patients initially treated with lurasidone in the acute phase achieved recovery status in the continuation study. Treatment with lurasidone (vs. placebo) earlier in the course of the bipolar depressive episode increased the likelihood of subsequent recovery. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  18. SREB Study Indicates Serious Shortage of Nursing Faculty.

    ERIC Educational Resources Information Center

    Southern Regional Education Board, Atlanta, GA. Council on Collegiate Education for Nursing.

    The Southern Regional Education Board (SREB) Council on Collegiate Education for Nursing appointed an ad hoc committee to study the implications of nursing shortages for nursing education programs in the 16 SREB states and the District of Columbia. In May 2001, surveys were sent to 491 colleges and universities that prepare students for licensure…

  19. Relationship between Omnibus and Post-hoc Tests: An Investigation of performance of the F test in ANOVA.

    PubMed

    Chen, Tian; Xu, Manfei; Tu, Justin; Wang, Hongyue; Niu, Xiaohui

    2018-02-25

    Comparison of groups is a common statistical test in many biomedical and psychosocial research studies. When there are more than two groups, one first performs an omnibus test for an overall difference across the groups. If this null is rejected, one then proceeds to the next step of post-hoc pairwise group comparisons to determine sources of difference. Otherwise, one stops and declares no group difference. A common belief is that if the omnibus test is significant, there must exist at least two groups that are significantly different and vice versa. Thus, when the omnibus test is significant, but no post-hoc between-group comparison shows significant difference, one is bewildered at what is going on and wondering how to interpret the results. At the end of the spectrum, when the omnibus test is not significant, one wonders if all post-hoc tests will be non-significant as well so that stopping after a nonsignificant omnibus test will not lead to any missed opportunity of finding group difference. In this report, we investigate this perplexing phenomenon and discuss how to interpret such results.

  20. Long-term healthcare costs and functional outcomes associated with lack of remission in schizophrenia: a post-hoc analysis of a prospective observational study

    PubMed Central

    2012-01-01

    Background Little is known about the long-term outcomes for patients with schizophrenia who fail to achieve symptomatic remission. This post-hoc analysis of a 3-year study compared the costs of mental health services and functional outcomes between individuals with schizophrenia who met or did not meet cross-sectional symptom remission at study enrollment. Methods This post-hoc analysis used data from a large, 3-year prospective, non-interventional observational study of individuals treated for schizophrenia in the United States conducted between July 1997 and September 2003. At study enrollment, individuals were classified as non-remitted or remitted using the Schizophrenia Working Group Definition of symptom remission (8 core symptoms rated as mild or less). Mental health service use was measured using medical records. Costs were based on the sites’ medical information systems. Functional outcomes were measured with multiple patient-reported measures and the clinician-rated Quality of Life Scale (QLS). Symptoms were measured using the Positive and Negative Syndrome Scale (PANSS). Outcomes for non-remitted and remitted patients were compared over time using mixed effects models for repeated measures or generalized estimating equations after adjusting for multiple baseline characteristics. Results At enrollment, most of the 2,284 study participants (76.1%) did not meet remission criteria. Non-remitted patients had significantly higher PANSS total scores at baseline, a lower likelihood of being Caucasian, a higher likelihood of hospitalization in the previous year, and a greater likelihood of a substance use diagnosis (all p < 0.05). Total mental health costs were significantly higher for non-remitted patients over the 3-year study (p = 0.008). Non-remitted patients were significantly more likely to be victims of crime, exhibit violent behavior, require emergency services, and lack paid employment during the 3-year study (all p < 0.05). Non-remitted patients also

  1. Added value of second biopsy target in screen-detected widespread suspicious breast calcifications.

    PubMed

    Falkner, Nathalie M; Hince, Dana; Porter, Gareth; Dessauvagie, Ben; Jeganathan, Sanjay; Bulsara, Max; Lo, Glen

    2018-06-01

    There is controversy on the optimal work-up of screen-detected widespread breast calcifications: whether to biopsy a single target or multiple targets. This study evaluates agreement between multiple biopsy targets within the same screen-detected widespread (≥25 mm) breast calcification to determine if the second biopsy adds value. Retrospective observational study of women screened in a statewide general population risk breast cancer mammographic screening program from 2009 to 2016. Screening episodes recalled for widespread calcifications where further views indicated biopsy, and two or more separate target areas were sampled within the same lesion were included. Percentage agreement and Cohen's Kappa were calculated. A total of 293317 women were screened during 761124 separate episodes with recalls for widespread calcifications in 2355 episodes. In 171 women, a second target was biopsied within the same lesion. In 149 (86%) cases, the second target biopsy result agreed with the first biopsy (κ = 0.6768). Agreement increased with increasing mammography score (85%, 86% and 92% for score 3, 4 and 5 lesions). Same day multiple biopsied lesions were three times more likely to yield concordant results compared to post-hoc second target biopsy cases. While a single target biopsy is sufficient to discriminate a benign vs. malignant diagnosis in most cases, in 14% there is added value in performing a second target biopsy. Biopsies performed prospectively are more likely to yield concordant results compared to post-hoc second target biopsy cases, suggesting a single prospective biopsy may be sufficient when results are radiological-pathological concordant; discordance still requires repeat sampling. © 2018 The Royal Australian and New Zealand College of Radiologists.

  2. Spinning AdS loop diagrams: two point functions

    NASA Astrophysics Data System (ADS)

    Giombi, Simone; Sleight, Charlotte; Taronna, Massimo

    2018-06-01

    We develop a systematic approach to evaluating AdS loop amplitudes with spinning legs based on the spectral (or "split") representation of bulk-to-bulk propagators, which re-expresses loop diagrams in terms of spectral integrals and higher-point tree diagrams. In this work we focus on 2pt one-loop Witten diagrams involving totally symmetric fields of arbitrary mass and integer spin. As an application of this framework, we study the contribution to the anomalous dimension of higher-spin currents generated by bubble diagrams in higher-spin gauge theories on AdS.

  3. The Importance of Corpora in Translation Studies: A Practical Case

    ERIC Educational Resources Information Center

    Bermúdez Bausela, Montserrat

    2016-01-01

    This paper deals with the use of corpora in Translation Studies, particularly with the so-called "'ad hoc' corpus" or "translator's corpus" as a working tool both in the classroom and for the professional translator. We believe that corpora are an inestimable source not only for terminology and phraseology extraction (cf. Maia,…

  4. Thermodynamic and classical instability of AdS black holes in fourth-order gravity

    NASA Astrophysics Data System (ADS)

    Myung, Yun Soo; Moon, Taeyoon

    2014-04-01

    We study thermodynamic and classical instability of AdS black holes in fourth-order gravity. These include the BTZ black hole in new massive gravity, Schwarzschild-AdS black hole, and higher-dimensional AdS black holes in fourth-order gravity. All thermo-dynamic quantities which are computed using the Abbot-Deser-Tekin method are used to study thermodynamic instability of AdS black holes. On the other hand, we investigate the s-mode Gregory-Laflamme instability of the massive graviton propagating around the AdS black holes. We establish the connection between the thermodynamic instability and the GL instability of AdS black holes in fourth-order gravity. This shows that the Gubser-Mitra conjecture holds for AdS black holes found from fourth-order gravity.

  5. Floquet scalar dynamics in global AdS

    NASA Astrophysics Data System (ADS)

    Biasi, Anxo; Carracedo, Pablo; Mas, Javier; Musso, Daniele; Serantes, Alexandre

    2018-04-01

    We study periodically driven scalar fields and the resulting geometries with global AdS asymptotics. These solutions describe the strongly coupled dynamics of dual finite-size quantum systems under a periodic driving which we interpret as Floquet condensates. They span a continuous two-parameter space that extends the linearized solutions on AdS. We map the regions of stability in the solution space. In a significant portion of the unstable subspace, two very different endpoints are reached depending upon the sign of the perturbation. Collapse into a black hole occurs for one sign. For the opposite sign instead one attains a regular solution with periodic modulation. We also construct quenches where the driving frequency and amplitude are continuously varied. Quasistatic quenches can interpolate between pure AdS and sourced solutions with time periodic vev. By suitably choosing the quasistatic path one can obtain boson stars dual to Floquet condensates at zero driving field. We characterize the adiabaticity of the quenching processes. Besides, we speculate on the possible connections of this framework with time crystals.

  6. Antismoking Ads at the Point of Sale: The Influence of Ad Type and Context on Ad Reactions.

    PubMed

    Kim, Annice; Nonnemaker, James; Guillory, Jamie; Shafer, Paul; Parvanta, Sarah; Holloway, John; Farrelly, Matthew

    2017-06-01

    Efforts are underway to educate consumers about the dangers of smoking at the point of sale (POS). Research is limited about the efficacy of POS antismoking ads to guide campaign development. This study experimentally tests whether the type of antismoking ad and the context in which ads are viewed influence people's reactions to the ads. A national convenience sample of 7,812 adult current smokers and recent quitters was randomized to 1 of 39 conditions. Participants viewed one of the four types of antismoking ads (negative health consequences-graphic, negative social consequences-intended emotive, benefits of quitting-informational, benefits of quitting-graphic) in one of the three contexts (alone, next to a cigarette ad, POS tobacco display). We assessed participants' reactions to the ads, including perceived effectiveness, negative emotion, affective dissonance, and motivational reaction. Graphic ads elicited more negative emotion and affective dissonance than benefits of quitting ads. Graphic ads elicited higher perceived effectiveness and more affective dissonance than intended emotive ads. Antismoking ads fared best when viewed alone, and graphic ads were least influenced by the context in which they were viewed. These results suggest that in developing POS campaigns, it is important to consider the competitive pro-tobacco context in which antismoking ads will be viewed.

  7. Constructing the AdS dual of a Fermi liquid: AdS black holes with Dirac hair

    NASA Astrophysics Data System (ADS)

    Čubrović, Mihailo; Zaanen, Jan; Schalm, Koenraad

    2011-10-01

    We provide evidence that the holographic dual to a strongly coupled charged Fermi liquid has a non-zero fermion density in the bulk. We show that the pole-strength of the stable quasiparticle characterizing the Fermi surface is encoded in the AdS probability density of a single normalizable fermion wavefunction in AdS. Recalling Migdal's theorem which relates the pole strength to the Fermi-Dirac characteristic discontinuity in the number density at ω F , we conclude that the AdS dual of a Fermi liquid is described by occupied on-shell fermionic modes in AdS. Encoding the occupied levels in the total spatially averaged probability density of the fermion field directly, we show that an AdS Reissner-Nordström black holein a theory with charged fermions has a critical temperature, at which the system undergoes a first-order transition to a black hole with a non-vanishing profile for the bulk fermion field. Thermodynamics and spectral analysis support that the solution with non-zero AdS fermion-profile is the preferred ground state at low temperatures.

  8. Identification of VaD and AD prodromes: the Cache County Study.

    PubMed

    Hayden, K M; Warren, L H; Pieper, C F; Østbye, T; Tschanz, J T; Norton, M C; Breitner, J C S; Welsh-Bohmer, K A

    2005-07-01

    It is unclear whether vascular dementia (VaD) has a cognitive prodrome, akin to the mild cognitive impairment (MCI) prodrome to Alzheimer's dementia (AD). To evaluate whether VaD has a cognitive prodrome, and if it can be differentiated from prodromal AD, we examined neuropsychological test performance of participants in a nested case-control study within a population-based cohort aged 65 or older. Participants (n = 485) were identified from the Cache County Study, a large population-based study of aging and dementia. After an average of 3 years of follow-up, a total of 62 incident dementia cases were identified (14 VaD, 48 AD). We identified a number of neuropsychological tests (executive and memory) that discriminated between diagnosed VaD and AD cases. Multivariate analyses sought to differentiate between these same groups 3 years before clinical diagnosis. The Consortium to Establish a Registry for Alzheimer's Disease Word List Recognition Test correct recognition of foils (mean difference, 1.25; 95% confidence interval [CI], 0.42 to 2.07; p < 0.01), Logical Memory I (mean difference, 7.16; 95% CI, 0.78 to 13.55, p < 0.05), Logical Memory II delayed recall (mean difference, 8.67; 95% CI, 1.59 to 15.74, p < 0.05), and percent savings (mean difference, 51.07; 95% CI, 32.58 to 69.56, p < 0.0001) differentiated VaD from AD cases after adjustment for age, sex, education, and dementia severity. Three years before dementia diagnosis, word list recognition ("no" responses mean difference, 1.40; 95% CI, 0.64 to 2.17; p < 0.001, and "yes" responses mean difference, -1.14; 95% CI, -2.14 to -0.13; p < 0.03) discriminated between prodromal VaD and AD. These results suggest that VaD has a prodromal syndrome, the cognitive features of which are distinguishable from the cognitive prodrome of AD.

  9. Sigsearch: a new term for post hoc unplanned search for statistically significant relationships with the intent to create publishable findings.

    PubMed

    Hashim, Muhammad Jawad

    2010-09-01

    Post-hoc secondary data analysis with no prespecified hypotheses has been discouraged by textbook authors and journal editors alike. Unfortunately no single term describes this phenomenon succinctly. I would like to coin the term "sigsearch" to define this practice and bring it within the teaching lexicon of statistics courses. Sigsearch would include any unplanned, post-hoc search for statistical significance using multiple comparisons of subgroups. It would also include data analysis with outcomes other than the prespecified primary outcome measure of a study as well as secondary data analyses of earlier research.

  10. Post-hoc simulation study to adopt a computerized adaptive testing (CAT) for a Korean Medical License Examination.

    PubMed

    Seo, Dong Gi; Choi, Jeongwook

    2018-05-17

    Computerized adaptive testing (CAT) has been adopted in license examinations due to a test efficiency and accuracy. Many research about CAT have been published to prove the efficiency and accuracy of measurement. This simulation study investigated scoring method and item selection methods to implement CAT in Korean medical license examination (KMLE). This study used post-hoc (real data) simulation design. The item bank used in this study was designed with all items in a 2017 KMLE. All CAT algorithms for this study were implemented by a 'catR' package in R program. In terms of accuracy, Rasch and 2parametric logistic (PL) model performed better than 3PL model. Modal a Posteriori (MAP) or Expected a Posterior (EAP) provided more accurate estimates than MLE and WLE. Furthermore Maximum posterior weighted information (MPWI) or Minimum expected posterior variance (MEPV) performed better than other item selection methods. In terms of efficiency, Rasch model was recommended to reduce test length. Simulation study should be performed under varied test conditions before adopting a live CAT. Based on a simulation study, specific scoring and item selection methods should be predetermined before implementing a live CAT.

  11. FHWA White Paper on Mobile Ad Hoc Networks

    DOT National Transportation Integrated Search

    2018-01-01

    Advanced next generation communications technologies offer the potential to greatly improve safety, system efficiency, and mobility across our Nations roadways. These new technologies and processes can address both traditionally difficult as well ...

  12. Supporting Secure, AD HOC Joins for Tactical Networks

    DTIC Science & Technology

    2002-05-07

    ftp.isi.edu/in-notes/ rfc2501.txt (20SEP01). [4] Deitel , Harvery M. and Paul J. Deitel . Java: How to Program 3rd Edition. (Prentice Hall: New...produce a complete product, to include the construction of TTNT hardware. The TTNT program is concerned with frequency hopping schemes, error correcting...Configuration To create the digital certificates needed for the client authentication, we modified a hybrid file encryption program that used a Rivest-Shamir

  13. ICTNET at Web Track 2012 Ad-hoc Task

    DTIC Science & Technology

    2012-11-01

    Model and use it as baseline this year. 3.2 Learning to rank Learning to rank (LTR) introduces machine learning to retrieval ranking problem. It...Yoram Singer. An efficient boosting algorithm  for  combining preferences [J]. The Journal of  Machine   Learning  Research. 2003. 

  14. Enabling Secure High-Performance Wireless Ad Hoc Networking

    DTIC Science & Technology

    2003-05-29

    destinations, consuming energy and available bandwidth. An attacker may similarly create a routing black hole, in which all packets are dropped: by sending...of the vertex cut, for example by forwarding only routing packets and not data packets, such that the nodes waste energy forwarding packets to the...with limited resources, including network bandwidth and the CPU processing capacity, memory, and battery power ( energy ) of each individual node in the

  15. Secure Ad Hoc Networking on an Android Platform

    DTIC Science & Technology

    2014-05-01

    Once the device is provisioned, connections can be initiated by tapping two devices together, this uses NFC to bootstrap a Bluetooth connection. Once...4 2.2 Residual Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Device Provisioning 5 3.1...the inclusion of SE Android’s Install-time Mandatory Access Control (MAC) feature. Some knowledge of Android is required to understand the system

  16. Robust Connectivity in Sensory and Ad Hoc Network

    DTIC Science & Technology

    2011-02-01

    as the prior probability is π0 = 0.8, the error probability should be capped at 0.2. This seemingly pathological result is due to the fact that the...publications and is the author of the book Multirate and Wavelet Signal Processing (Academic Press, 1998). His research interests include multiscale signal and

  17. Accurate ab initio quartic force fields for the ions HCO(+) and HOC(+)

    NASA Technical Reports Server (NTRS)

    Martin, J. M. L.; Taylor, Peter R.; Lee, Timothy J.

    1993-01-01

    The quartic force fields of HCO(+) and HOC(+) have been computed using augmented coupled cluster methods and basis sets of spdf and spdfg quality. Calculations on HCN, CO, and N2 have been performed to assist in calibrating the computed results. Going from an spdf to an spdfg basis shortens triple bonds by about 0.004 A, and increases the corresponding harmonic frequency by 10-20/cm, leaving bond distances about 0.003 A too long and triple bond stretching frequencies about 5/cm too low. Accurate estimates for the bond distances, fundamental frequencies, and thermochemical quantities are given. HOC(+) lies 37.8 +/- 0.5 kcal/mol (0 K) above HCO(+); the classical barrier height for proton exchange is 76.7 +/- 1.0 kcal/mol.

  18. Vacuum degeneracy and Conformal Mass in Lovelock AdS gravity

    NASA Astrophysics Data System (ADS)

    Arenas-Henriquez, Gabriel; Miskovic, Olivera; Olea, Rodrigo

    2017-11-01

    It is shown that the notion of Conformal Mass can be defined within a given anti-de Sitter (AdS) branch of a Lovelock gravity theory as long as the corresponding vacuum is not degenerate. Indeed, conserved charges obtained by the addition of Kounterterms to the bulk action turn out to be proportional to the electric part of the Weyl tensor, when the fall-off of a generic solution in that AdS branch is considered. The factor of proportionality is the degeneracy condition for the vacua in the particular Lovelock AdS theory under study. This last feature explains the obstruction to define Conformal Mass in the degenerate case.

  19. Post-hoc analysis of randomised, placebo-controlled, double-blind study (MCI186-19) of edaravone (MCI-186) in amyotrophic lateral sclerosis.

    PubMed

    Takei, Koji; Takahashi, Fumihiro; Liu, Shawn; Tsuda, Kikumi; Palumbo, Joseph

    2017-10-01

    Post-hoc analyses of the ALS Functional Rating Scale-Revised (ALSFRS-R) score data, the primary endpoint in the 24-week double-blind placebo-controlled study of edaravone (MCI186-19, NCT01492686), were performed to confirm statistical robustness of the result. The previously reported original analysis had used a last observation carried forward (LOCF) method and also excluded patients with fewer than three completed treatment cycles. The post-hoc sensitivity analyses used different statistical methods as follows: 1) including all patients regardless of treatment cycles received (ALL LOCF); 2) a mixed model for repeated measurements (MMRM) analysis; and 3) the Combined Assessment of Function and Survival (CAFS) endpoint. Findings were consistent with the original primary analysis in showing superiority of edaravone over placebo. We also investigated the distribution of change in ALSFRS-R total score across all patients in the study as well as which ALSFRS-R items and domains may have contributed to the overall efficacy findings. The distribution of changes in ALSFRS-R total score from baseline to the end of cycle 6 (ALL LOCF) shifted in favour of edaravone compared to placebo. Edaravone was descriptively favoured for each ALSFRS-R item and each of the four ALSFRS-R domains at the end of cycle 6 (ALL LOCF), suggesting a generalised effect of edaravone in slowing functional decline across all anatomical regions. The effect of edaravone appeared to be similar in patients with bulbar onset and limb onset. Together, these observations would be consistent with its putative neuroprotective effects against the development of oxidative damage unspecific to anatomical regions.

  20. A post-hoc subgroup analysis of outcomes in the first phase III clinical study of edaravone (MCI-186) in amyotrophic lateral sclerosis.

    PubMed

    2017-10-01

    Our first phase III study failed to demonstrate efficacy of edaravone for amyotrophic lateral sclerosis (ALS) compared to placebo. Here, we performed post-hoc subgroup analysis to identify a subgroup in which edaravone might be expected to show efficacy. We focussed on two newly defined subgroups, EESP and dpEESP2y. The EESP was defined as the efficacy-expected subpopulation with % forced vital capacity of ≥80%, and ≥2 points for all item scores in the revised ALS functional rating scale (ALSFRS-R) score before treatment. The dpEESP2y was defined as the greater-efficacy-expected subpopulation within EESP having a diagnosis of 'definite' or 'probable' ALS according to the El Escorial revised Airlie House diagnostic criteria and onset of disease within two years. The primary endpoint of the post-hoc analysis was the change in the ALSFRS-R score during the 24-week treatment period. The intergroup differences of the least-squares mean change in the ALSFRS-R score ± standard error during treatment were 0.65 ± 0.78 (p = 0.4108) in the full analysis set, 2.20 ± 1.03 (p = 0.0360) in the EESP, and 3.01 ± 1.33 (p = 0.0270) in the dpEESP2y. Edaravone exhibited efficacy in the dpEESP2y subgroup. A further clinical study in patients meeting dpEESP2y criteria is warranted.

  1. Immune Inspired Security Approach for Manets: a Case Study

    NASA Astrophysics Data System (ADS)

    Mohamed, Yasir Abdelgadir

    2011-06-01

    This paper extends the work that has earlier been established. Immune inspired approach for securing mobile ad hoc networks is specified there. Although it is clearly indicated there that the research scope is the wireless networks in general and hybrid mobile ad hoc networks in particular, we have seen that specifying the security system in one of the communications applications that need further security approach may help to understand how effectively the system can contribute to this vital and important networks sector. Security in this type of networks is important and controversial as it plays a key role in users' eagerness or reluctance for the services provided by these networks. In this paper, the immune inspired security system is specified to secure web services in converged networks.

  2. Warped AdS3 black holes

    NASA Astrophysics Data System (ADS)

    Song, Wei; Anninos, Dionysios; Li, Wei; Padi, Megha; Strominger, Andrew

    2009-03-01

    Three dimensional topologically massive gravity (TMG) with a negative cosmological constant -ell-2 and positive Newton constant G admits an AdS3 vacuum solution for any value of the graviton mass μ. These are all known to be perturbatively unstable except at the recently explored chiral point μell = 1. However we show herein that for every value of μell ≠ 3 there are two other (potentially stable) vacuum solutions given by SL(2,Bbb R) × U(1)-invariant warped AdS3 geometries, with a timelike or spacelike U(1) isometry. Critical behavior occurs at μell = 3, where the warping transitions from a stretching to a squashing, and there are a pair of warped solutions with a null U(1) isometry. For μell > 3, there are known warped black hole solutions which are asymptotic to warped AdS3. We show that these black holes are discrete quotients of warped AdS3 just as BTZ black holes are discrete quotients of ordinary AdS3. Moreover new solutions of this type, relevant to any theory with warped AdS3 solutions, are exhibited. Finally we note that the black hole thermodynamics is consistent with the hypothesis that, for μell > 3, the warped AdS3 ground state of TMG is holographically dual to a 2D boundary CFT with central charges c_R-formula and c_L-formula.

  3. Warped AdS3 black holes

    NASA Astrophysics Data System (ADS)

    Anninos, Dionysios; Li, Wei; Padi, Megha; Song, Wei; Strominger, Andrew

    2009-03-01

    Three dimensional topologically massive gravity (TMG) with a negative cosmological constant -l-2 and positive Newton constant G admits an AdS3 vacuum solution for any value of the graviton mass μ. These are all known to be perturbatively unstable except at the recently explored chiral point μl = 1. However we show herein that for every value of μl ≠ 3 there are two other (potentially stable) vacuum solutions given by SL(2,Bbb R) × U(1)-invariant warped AdS3 geometries, with a timelike or spacelike U(1) isometry. Critical behavior occurs at μl = 3, where the warping transitions from a stretching to a squashing, and there are a pair of warped solutions with a null U(1) isometry. For μl > 3, there are known warped black hole solutions which are asymptotic to warped AdS3. We show that these black holes are discrete quotients of warped AdS3 just as BTZ black holes are discrete quotients of ordinary AdS3. Moreover new solutions of this type, relevant to any theory with warped AdS3 solutions, are exhibited. Finally we note that the black hole thermodynamics is consistent with the hypothesis that, for μl > 3, the warped AdS3 ground state of TMG is holographically dual to a 2D boundary CFT with central charges c_R-formula and c_L-formula.

  4. Monitoring of slope-instabilities and deformations with Micro-Electro-Mechanical-Systems (MEMS) in wireless ad-hoc Sensor Networks

    NASA Astrophysics Data System (ADS)

    Arnhardt, C.; Fernández-Steeger, T. M.; Azzam, R.

    2009-04-01

    In most mountainous regions, landslides represent a major threat to human life, properties and infrastructures. Nowadays existing landslide monitoring systems are often characterized by high efforts in terms of purchase, installation, maintenance, manpower and material. In addition (or because of this) only small areas or selective points of the endangered zone can be observed by the system. Therefore the improvement of existing and the development of new monitoring and warning systems are of high relevance. The joint project "Sensor based Landslide Early Warning Systems" (SLEWS) deals with the development of a prototypic Alarm- and Early Warning system (EWS) for different types of landslides using low-cost micro-sensors (MEMS) integrated in a wireless sensor network (WSN). Modern so called Ad-Hoc, Multi-Hop wireless sensor networks (WSN) are characterized by a self organizing and self-healing capacity of the system (autonomous systems). The network consists of numerous individual and own energy-supply operating sensor nodes, that can send data packages from their measuring devices (here: MEMS) over other nodes (Multi-Hop) to a collection point (gateway). The gateway provides the interface to central processing and data retrieval units (PC, Laptop or server) outside the network. In order to detect and monitor the different landslide processes (like fall, topple, spreading or sliding) 3D MEMS capacitive sensors made from single silicon crystals and glass were chosen to measure acceleration, tilting and altitude changes. Based on the so called MEMS (Micro-Electro-Mechanical Systems) technology, the sensors combine very small mechanical and electronic units, sensing elements and transducers on a small microchip. The mass production of such type of sensors allows low cost applications in different areas (like automobile industries, medicine, and automation technology). Apart from the small and so space saving size and the low costs another advantage is the energy

  5. The Traffic Adaptive Data Dissemination (TrAD) Protocol for both Urban and Highway Scenarios.

    PubMed

    Tian, Bin; Hou, Kun Mean; Zhou, Haiying

    2016-06-21

    The worldwide economic cost of road crashes and injuries is estimated to be US$518 billion per year and the annual congestion cost in France is estimated to be €5.9 billion. Vehicular Ad hoc Networks (VANETs) are one solution to improve transport features such as traffic safety, traffic jam and infotainment on wheels, where a great number of event-driven messages need to be disseminated in a timely way in a region of interest. In comparison with traditional wireless networks, VANETs have to consider the highly dynamic network topology and lossy links due to node mobility. Inter-Vehicle Communication (IVC) protocols are the keystone of VANETs. According to our survey, most of the proposed IVC protocols focus on either highway or urban scenarios, but not on both. Furthermore, too few protocols, considering both scenarios, can achieve high performance. In this paper, an infrastructure-less Traffic Adaptive data Dissemination (TrAD) protocol which takes into account road traffic and network traffic status for both highway and urban scenarios will be presented. TrAD has double broadcast suppression techniques and is designed to adapt efficiently to the irregular road topology. The performance of the TrAD protocol was evaluated quantitatively by means of realistic simulations taking into account different real road maps, traffic routes and vehicular densities. The obtained simulation results show that TrAD is more efficient in terms of packet delivery ratio, number of transmissions and delay in comparison with the performance of three well-known reference protocols. Moreover, TrAD can also tolerate a reasonable degree of GPS drift and still achieve efficient data dissemination.

  6. The Traffic Adaptive Data Dissemination (TrAD) Protocol for both Urban and Highway Scenarios

    PubMed Central

    Tian, Bin; Hou, Kun Mean; Zhou, Haiying

    2016-01-01

    The worldwide economic cost of road crashes and injuries is estimated to be US$518 billion per year and the annual congestion cost in France is estimated to be €5.9 billion. Vehicular Ad hoc Networks (VANETs) are one solution to improve transport features such as traffic safety, traffic jam and infotainment on wheels, where a great number of event-driven messages need to be disseminated in a timely way in a region of interest. In comparison with traditional wireless networks, VANETs have to consider the highly dynamic network topology and lossy links due to node mobility. Inter-Vehicle Communication (IVC) protocols are the keystone of VANETs. According to our survey, most of the proposed IVC protocols focus on either highway or urban scenarios, but not on both. Furthermore, too few protocols, considering both scenarios, can achieve high performance. In this paper, an infrastructure-less Traffic Adaptive data Dissemination (TrAD) protocol which takes into account road traffic and network traffic status for both highway and urban scenarios will be presented. TrAD has double broadcast suppression techniques and is designed to adapt efficiently to the irregular road topology. The performance of the TrAD protocol was evaluated quantitatively by means of realistic simulations taking into account different real road maps, traffic routes and vehicular densities. The obtained simulation results show that TrAD is more efficient in terms of packet delivery ratio, number of transmissions and delay in comparison with the performance of three well-known reference protocols. Moreover, TrAD can also tolerate a reasonable degree of GPS drift and still achieve efficient data dissemination. PMID:27338393

  7. AdS6 solutions of type II supergravity

    NASA Astrophysics Data System (ADS)

    Apruzzi, Fabio; Fazzi, Marco; Passias, Achilleas; Rosa, Dario; Tomasiello, Alessandro

    2014-11-01

    Very few AdS6 × M 4 supersymmetric solutions are known: one in massive IIA, and two IIB solutions dual to it. The IIA solution is known to be unique; in this paper, we use the pure spinor approach to give a classification for IIB supergravity. We reduce the problem to two PDEs on a two-dimensional space Σ. M 4 is then a fibration of S 2 over Σ; the metric and fluxes are completely determined in terms of the solution to the PDEs. The results seem likely to accommodate near-horizon limits of ( p, q)-fivebrane webs studied in the literature as a source of CFT5's. We also show that there are no AdS6 solutions in eleven-dimensional supergravity.

  8. Reflections on the added value of using mixed methods in the SCAPE study.

    PubMed

    Murphy, Kathy; Casey, Dympna; Devane, Declan; Meskell, Pauline; Higgins, Agnes; Elliot, Naomi; Lalor, Joan; Begley, Cecily

    2014-03-01

    To reflect on the added value that a mixed method design gave in a large national evaluation study of specialist and advanced practice (SCAPE), and to propose a reporting guide that could help make explicit the added value of mixed methods in other studies. Recently, researchers have focused on how to carry out mixed methods research (MMR) rigorously. The value-added claims for MMR include the capacity to exploit the strengths and compensate for weakness inherent in single designs, generate comprehensive description of phenomena, produce more convincing results for funders or policy-makers and build methodological expertise. Data illustrating value added claims were drawn from the SCAPE study. Studies about the purpose of mixed methods were identified from a search of literature. The authors explain why and how they undertook components of the study, and propose a guideline to facilitate such studies. If MMR is to become the third methodological paradigm, then articulation of what extra benefit MMR adds to a study is essential. The authors conclude that MMR has added value and found the guideline useful as a way of making value claims explicit. The clear articulation of the procedural aspects of mixed-methods research, and identification of a guideline to facilitate such research, will enable researchers to learn more effectively from each other.

  9. Position space analysis of the AdS (in)stability problem

    NASA Astrophysics Data System (ADS)

    Dimitrakopoulos, Fotios V.; Freivogel, Ben; Lippert, Matthew; Yang, I.-Sheng

    2015-08-01

    We investigate whether arbitrarily small perturbations in global AdS space are generically unstable and collapse into black holes on the time scale set by gravitational interactions. We argue that current evidence, combined with our analysis, strongly suggests that a set of nonzero measure in the space of initial conditions does not collapse on this time scale. We perform an analysis in position space to study this puzzle, and our formalism allows us to directly study the vanishing-amplitude limit. We show that gravitational self-interaction leads to tidal deformations which are equally likely to focus or defocus energy, and we sketch the phase diagram accordingly. We also clarify the connection between gravitational evolution in global AdS and holographic thermalization.

  10. Holographic Rényi entropy in AdS3/LCFT2 correspondence

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Song, Feng-yan; Zhang, Jia-ju

    2014-03-01

    The recent study in AdS3/CFT2 correspondence shows that the tree level contribution and 1-loop correction of holographic Rényi entanglement entropy (HRE) exactly match the direct CFT computation in the large central charge limit. This allows the Rényi entanglement entropy to be a new window to study the AdS/CFT correspondence. In this paper we generalize the study of Rényi entanglement entropy in pure AdS3 gravity to the massive gravity theories at the critical points. For the cosmological topological massive gravity (CTMG), the dual conformal field theory (CFT) could be a chiral conformal field theory or a logarithmic conformal field theory (LCFT), depending on the asymptotic boundary conditions imposed. In both cases, by studying the short interval expansion of the Rényi entanglement entropy of two disjoint intervals with small cross ratio x, we find that the classical and 1-loop HRE are in exact match with the CFT results, up to order x 6. To this order, the difference between the massless graviton and logarithmic mode can be seen clearly. Moreover, for the cosmological new massive gravity (CNMG) at critical point, which could be dual to a logarithmic CFT as well, we find the similar agreement in the CNMG/LCFT correspondence. Furthermore we read the 2-loop correction of graviton and logarithmic mode to HRE from CFT computation. It has distinct feature from the one in pure AdS3 gravity.

  11. Continuous-spin mixed-symmetry fields in AdS(5)

    NASA Astrophysics Data System (ADS)

    Metsaev, R. R.

    2018-05-01

    Free mixed-symmetry continuous-spin fields propagating in AdS(5) space and flat R(4,1) space are studied. In the framework of a light-cone gauge formulation of relativistic dynamics, we build simple actions for such fields. The realization of relativistic symmetries on the space of light-cone gauge mixed-symmetry continuous-spin fields is also found. Interrelations between constant parameters entering the light-cone gauge actions and eigenvalues of the Casimir operators of space-time symmetry algebras are obtained. Using these interrelations and requiring that the field dynamics in AdS(5) be irreducible and classically unitary, we derive restrictions on the constant parameters and eigenvalues of the second-order Casimir operator of the algebra.

  12. Moving Beyond Univariate Post-Hoc Testing in Exercise Science: A Primer on Descriptive Discriminate Analysis.

    PubMed

    Barton, Mitch; Yeatts, Paul E; Henson, Robin K; Martin, Scott B

    2016-12-01

    There has been a recent call to improve data reporting in kinesiology journals, including the appropriate use of univariate and multivariate analysis techniques. For example, a multivariate analysis of variance (MANOVA) with univariate post hocs and a Bonferroni correction is frequently used to investigate group differences on multiple dependent variables. However, this univariate approach decreases power, increases the risk for Type 1 error, and contradicts the rationale for conducting multivariate tests in the first place. The purpose of this study was to provide a user-friendly primer on conducting descriptive discriminant analysis (DDA), which is a post-hoc strategy to MANOVA that takes into account the complex relationships among multiple dependent variables. A real-world example using the Statistical Package for the Social Sciences syntax and data from 1,095 middle school students on their body composition and body image are provided to explain and interpret the results from DDA. While univariate post hocs increased the risk for Type 1 error to 76%, the DDA identified which dependent variables contributed to group differences and which groups were different from each other. For example, students in the very lean and Healthy Fitness Zone categories for body mass index experienced less pressure to lose weight, more satisfaction with their body, and higher physical self-concept than the Needs Improvement Zone groups. However, perceived pressure to gain weight did not contribute to group differences because it was a suppressor variable. Researchers are encouraged to use DDA when investigating group differences on multiple correlated dependent variables to determine which variables contributed to group differences.

  13. The Report of the University Ad Hoc Committee on Instructional Media.

    ERIC Educational Resources Information Center

    North Carolina Univ., Greensboro.

    The University of North Carolina at Greensboro charged a committee with studying the needs of the university for special instructional media, surveying its existing resources in this area, and recommending a plan for coordination of use of instructional media. By and large, departments agreed that maintenance of existing equipment was an immediate…

  14. Collapse and Nonlinear Instability of AdS Space with Angular Momentum

    NASA Astrophysics Data System (ADS)

    Choptuik, Matthew W.; Dias, Óscar J. C.; Santos, Jorge E.; Way, Benson

    2017-11-01

    We present a numerical study of rotational dynamics in AdS5 with equal angular momenta in the presence of a complex doublet scalar field. We determine that the endpoint of gravitational collapse is a Myers-Perry black hole for high energies and a hairy black hole for low energies. We investigate the time scale for collapse at low energies E , keeping the angular momenta J ∝E in anti-de Sitter (AdS) length units. We find that the inclusion of angular momenta delays the collapse time, but retains a t ˜1 /E scaling. We perturb and evolve rotating boson stars, and find that boson stars near AdS space appear stable, but those sufficiently far from AdS space are unstable. We find that the dynamics of the boson star instability depend on the perturbation, resulting either in collapse to a Myers-Perry black hole, or development towards a stable oscillating solution.

  15. 42 CFR 422.2262 - Review and distribution of marketing materials.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM MEDICARE ADVANTAGE PROGRAM Medicare Advantage Marketing... model materials. (d) Ad hoc enrollee communication materials. Ad hoc enrollee communication materials...

  16. Hoc protein regulates the biological effects of T4 phage in mammals.

    PubMed

    Dabrowska, Krystyna; Zembala, Maria; Boratynski, Janusz; Switala-Jelen, Kinga; Wietrzyk, Joanna; Opolski, Adam; Szczaurska, Katarzyna; Kujawa, Marek; Godlewska, Joanna; Gorski, Andrzej

    2007-06-01

    We previously investigated the biological, non-antibacterial effects of bacteriophage T4 in mammals (binding to cancer cells in vitro and attenuating tumour growth and metastases in vivo); we selected the phage mutant HAP1 that was significantly more effective than T4. In this study we describe a non-sense mutation in the hoc gene that differentiates bacteriophage HAP1 and its parental strain T4. We found no substantial effects of the mutation on the mutant morphology, and its effects on electrophoretic mobility and hydrodynamic size were moderate. Only the high ionic strength of the environment resulted in a size difference of about 10 nm between T4 and HAP1. We compared the antimetastatic activity of the T2 phage, which does not express protein Hoc, with those of T4 and HAP1 (B16 melanoma lung colonies). We found that HAP1 and T2 decreased metastases with equal effect, more strongly than did T4. We also investigated concentrations of T4 and HAP1 in the murine blood, tumour (B16), spleen, liver, or muscle. We found that HAP1 was rapidly cleared from the organism, most probably by the liver. Although HAP1 was previously defined to bind cancer cells more effectively (than T4), its rapid elimination precluded its higher concentration in tumours.

  17. Influences of Dietary Added Sugar Consumption on Striatal Food-Cue Reactivity and Postprandial GLP-1 Response

    PubMed Central

    Dorton, Hilary M.; Luo, Shan; Monterosso, John R.; Page, Kathleen A.

    2018-01-01

    Sugar consumption in the United States exceeds recommendations from the American Heart Association. Overconsumption of sugar is linked to risk for obesity and metabolic disease. Animal studies suggest that high-sugar diets alter functions in brain regions associated with reward processing, including the dorsal and ventral striatum. Human neuroimaging studies have shown that these regions are responsive to food cues, and that the gut-derived satiety hormones, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY), suppress striatal food-cue responsivity. We aimed to determine the associations between dietary added sugar intake, striatal responsivity to food cues, and postprandial GLP-1 and PYY levels. Twenty-two lean volunteers underwent a functional magnetic resonance imaging (fMRI) scan during which they viewed pictures of food and non-food items after a 12-h fast. Before scanning, participants consumed a glucose drink. A subset of 19 participants underwent an additional fMRI session in which they consumed water as a control condition. Blood was sampled for GLP-1, and PYY levels and hunger ratings were assessed before and ~75 min after drink consumption. In-person 24-h dietary recalls were collected from each participant on three to six separate occasions over a 2-month period. Average percent calories from added sugar were calculated using information from 24-h dietary recalls. A region-of-interest analysis was performed to compare the blood oxygen level-dependent (BOLD) response to food vs. non-food cues in the bilateral dorsal striatum (caudate/putamen) and ventral striatum (nucleus accumbens). The relationships between added sugar, striatal responses, and hormone changes after drink consumption were assessed using Spearman’s correlations. We observed a positive correlation between added sugar intake and BOLD response to food cues in the dorsal striatum and a similar trend in the nucleus accumbens after glucose, but not water, consumption. Added sugar intake

  18. Influences of Dietary Added Sugar Consumption on Striatal Food-Cue Reactivity and Postprandial GLP-1 Response.

    PubMed

    Dorton, Hilary M; Luo, Shan; Monterosso, John R; Page, Kathleen A

    2017-01-01

    Sugar consumption in the United States exceeds recommendations from the American Heart Association. Overconsumption of sugar is linked to risk for obesity and metabolic disease. Animal studies suggest that high-sugar diets alter functions in brain regions associated with reward processing, including the dorsal and ventral striatum. Human neuroimaging studies have shown that these regions are responsive to food cues, and that the gut-derived satiety hormones, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY), suppress striatal food-cue responsivity. We aimed to determine the associations between dietary added sugar intake, striatal responsivity to food cues, and postprandial GLP-1 and PYY levels. Twenty-two lean volunteers underwent a functional magnetic resonance imaging (fMRI) scan during which they viewed pictures of food and non-food items after a 12-h fast. Before scanning, participants consumed a glucose drink. A subset of 19 participants underwent an additional fMRI session in which they consumed water as a control condition. Blood was sampled for GLP-1, and PYY levels and hunger ratings were assessed before and ~75 min after drink consumption. In-person 24-h dietary recalls were collected from each participant on three to six separate occasions over a 2-month period. Average percent calories from added sugar were calculated using information from 24-h dietary recalls. A region-of-interest analysis was performed to compare the blood oxygen level-dependent (BOLD) response to food vs. non-food cues in the bilateral dorsal striatum (caudate/putamen) and ventral striatum (nucleus accumbens). The relationships between added sugar, striatal responses, and hormone changes after drink consumption were assessed using Spearman's correlations. We observed a positive correlation between added sugar intake and BOLD response to food cues in the dorsal striatum and a similar trend in the nucleus accumbens after glucose, but not water, consumption. Added sugar intake

  19. Rotigotine and specific non-motor symptoms of Parkinson's disease: post hoc analysis of RECOVER.

    PubMed

    Ray Chaudhuri, K; Martinez-Martin, Pablo; Antonini, Angelo; Brown, Richard G; Friedman, Joseph H; Onofrj, Marco; Surmann, Erwin; Ghys, Liesbet; Trenkwalder, Claudia

    2013-07-01

    Non-motor symptoms of Parkinson's disease (PD) represent major causes of morbidity. RECOVER, a randomized controlled trial of rotigotine transdermal system, was the first prospective controlled trial to use the Non-Motor Symptoms Scale (NMSS) as an exploratory outcome for assessment of treatment effects on non-motor symptoms in PD. Rotigotine improved NMSS total score compared with placebo, and the "Sleep/fatigue" and "Mood/apathy" domains. This post hoc analysis further characterizes the effects of rotigotine on sleep/fatigue and mood/apathy. Patients with PD and unsatisfactory early-morning motor impairment were randomized to transdermal patches of rotigotine (2-16 mg/24 h) or placebo. Treatment was titrated to optimal dose over 1-8 weeks, maintained for 4 weeks. The NMSS was assessed at baseline and end of treatment. Post hoc analyses are presented for individual items of the "Sleep/fatigue" and "Mood/apathy" domains. The interpretation of p-values is considered exploratory in nature. Of 287 patients randomized, NMSS data were available for 267 patients (178 rotigotine, 89 placebo). Within the "Sleep/fatigue" domain there was a significant difference, in favor of rotigotine, in change from baseline score in 1 of 5 items: "fatigue (tiredness) or lack of energy" (ANCOVA, p < 0.0001). Within the "Mood/apathy" domain, there were significant differences in favor of rotigotine in 4 of 7 items: "lost interest in surroundings" (p < 0.0001), "lost interest in doing things" (p < 0.0001), "seems sad or depressed" (p < 0.01), and "difficulty experiencing pleasure" (p < 0.05). Rotigotine transdermal system may improve non-motor symptoms such as fatigue, symptoms of depression, anhedonia, and apathy in patients with PD; further prospective controlled studies are required to confirm this post hoc analysis. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. The Stability of Post Hoc Model Modifications in Covariance Structure Models.

    ERIC Educational Resources Information Center

    Hutchinson, Susan R.

    The work of R. MacCallum et al. (1992) was extended by examining chance modifications through a Monte Carlo simulation. The stability of post hoc model modifications was examined under varying sample size, model complexity, and severity of misspecification using 2- and 4-factor oblique confirmatory factor analysis (CFA) models with four and eight…

  1. On information loss in AdS 3/CFT 2

    DOE PAGES

    Fitzpatrick, A. Liam; Kaplan, Jared; Li, Daliang; ...

    2016-05-18

    We discuss information loss from black hole physics in AdS 3, focusing on two sharp signatures infecting CFT 2 correlators at large central charge c: ‘forbidden singularities’ arising from Euclidean-time periodicity due to the effective Hawking temperature, and late-time exponential decay in the Lorentzian region. We study an infinite class of examples where forbidden singularities can be resolved by non-perturbative effects at finite c, and we show that the resolution has certain universal features that also apply in the general case. Analytically continuing to the Lorentzian regime, we find that the non-perturbative effects that resolve forbidden singularities qualitatively change themore » behavior of correlators at times t ~S BH, the black hole entropy. This may resolve the exponential decay of correlators at late times in black hole backgrounds. By Borel resumming the 1/c expansion of exact examples, we explicitly identify ‘information-restoring’ effects from heavy states that should correspond to classical solutions in AdS 3. Lastly, our results suggest a line of inquiry towards a more precise formulation of the gravitational path integral in AdS 3.« less

  2. Stability of warped AdS3 vacua of topologically massive gravity

    NASA Astrophysics Data System (ADS)

    Anninos, Dionysios; Esole, Mboyo; Guica, Monica

    2009-10-01

    AdS3 vacua of topologically massive gravity (TMG) have been shown to be perturbatively unstable for all values of the coupling constant except the chiral point μl = 1. We study the possibility that the warped vacua of TMG, which exist for all values of μ, are stable under linearized perturbations. In this paper, we show that spacelike warped AdS3 vacua with Compère-Detournay boundary conditions are indeed stable in the range μl>3. This is precisely the range in which black hole solutions arise as discrete identifications of the warped AdS3 vacuum. The situation somewhat resembles chiral gravity: although negative energy modes do exist, they are all excluded by the boundary conditions, and the perturbative spectrum solely consists of boundary (pure large gauge) gravitons.

  3. Beyond AdS Space-times, New Holographic Correspondences and Applications

    NASA Astrophysics Data System (ADS)

    Ghodrati, Mahdis

    The AdS/CFT correspondence conjectures a mathematical equivalence between string theories and gauge theories. In a particular limit it allows a description of strongly coupled conformal field theory via weakly coupled gravity. This feature has been used to gain insight into many condensed matter (CM) systems. However, to apply the duality in more physical scenarios, one needs to go beyond the usual AdS/CFT framework and extend the duality to non-AdS situations. To describe Lifshitz and hyperscaling violating (HSV) phenomena in CM one uses gauge fields on the gravity side which naturally realize the breaking of Lorentz invariance. These gravity constructions often contain naked singularities. In this thesis, we construct a resolution of the infra-red (IR) singularity of the HSV background. The idea is to add squared curvature terms to the Einstein-Maxwell dilaton action to build a flow from AdS4 in the ultra violate (UV) to an intermediating HSV region and then to an AdS2 x R 2 region in the IR. This general solution is free from the naked singularities and would be more appropriate for applications of HSV in physical systems. We also study the Schwinger effect by using the AdS/CFT duality. We present the phase diagrams of the Schwinger effect and also the "butterfly shaped-phase diagrams" of the entanglement entropy for four different confining supergravity backgrounds. Comparing different features of all of these diagrams could point out to a potential relation between the Schwinger effect and the entanglement entropy which could lead to a method of measuring entanglement entropy in the laboratory. Finally, we study the "new massive gravity" theory and the different black hole solutions it admits. We first present three different methods of calculating the conserved charges. Then, by calculating the on-shell Gibbs free energy we construct the Hawking-Page phase diagrams for different solutions in two thermodynamical ensembles. As the massive gravity models are

  4. The Schooling Experience of Adolescent Boys with AD/HD: An Australian Case Study

    ERIC Educational Resources Information Center

    Gibbs, Kathryn; Mercer, K. Louise; Carrington, Suzanne

    2016-01-01

    This study explored the experience of schooling of six adolescent boys diagnosed with AD/HD from the perspectives of the boys, their mothers and their teachers. The study utilised social constructionism as the theoretical orientation and the Dynamic Developmental Theory (DDT) of AD/HD as the explanatory framework. Utilising a multiple,…

  5. Insight and Treatment Outcomes in Schizophrenia: Post-hoc Analysis of a Long-term, Double-blind Study Comparing Lurasidone and Quetiapine XR.

    PubMed

    Harvey, Philip D; Siu, Cynthia O; Loebel, Antony D

    2017-12-01

    Objective: The objective of this post-hoc analysis was to evaluate the effect of lurasidone and quetiapine extended-release (XR) on insight and judgment and assess the longitudinal relationships between improvement in insight and cognitive performance, functional capacity, quality of well-being, and depressive symptoms in patients with schizophrenia. Design: Clinically unstable patients with schizophrenia (N=488) were randomized to once-daily, fixed-dose treatment with lurasidone 80mg, lurasidone 160mg, quetiapine XR 600mg, or placebo, followed by a long-term, double-blind, flexible-dose continuation study involving these agents. Results: Significantly greater improvement in insight and judgment (assessed by the Positive and Negative Syndrome Scale G12 item) for the lurasidone and quetiapine XR groups, compared to the placebo group, was observed at Week 6. Over a subsequent six-month continuation period, the flexible dose lurasidone group showed significantly greater improvement in insight from acute phase baseline compared to the flexible-dose quetiapine XR group (QXR-QXR) (p=0.032). Improvement in insight was significantly correlated with improvement in cognition ( p =0.014), functional capacity (p=0.006, UPSA-B), quality of well-being ( p =0.033, QWB), and depressive symptoms ( p =0.05, Montgomery-Åsberg Depression Rating Scale [MADRS] score) across treatment groups and study periods. Conclusion: In this post-hoc analysis, flexibly dosed lurasidone 40 to 160mg/d was found to be associated with significantly greater improvement in insight compared to flexibly dosed quetiapine XR 200 to 800mg/d over long-term treatment in patients with schizophrenia. Across treatment groups, improvement in insight and judgment was significantly associated with improvement in cognition, functional capacity, quality of well-being, and depressive symptoms over time.

  6. String in AdS black hole: A thermo field dynamic approach

    NASA Astrophysics Data System (ADS)

    Cantcheff, M. Botta; Gadelha, Alexandre L.; Marchioro, Dáfni F. Z.; Nedel, Daniel Luiz

    2012-10-01

    Based on Maldacena’s description of an eternal anti-de Sitter (AdS) black hole, we reassess the thermo field dynamics (TFD) formalism in the context of the AdS/CFT correspondence. The model studied here involves the maximally extended AdS-Schwarschild solution and two (noninteracting) copies of the conformal field theory (CFT) associated to the global AdS spacetime, along with an extension of the string by imposing natural gluing conditions in the horizon. We show that the gluing conditions in the horizon define a string boundary state which is identified with the TFD thermal vacuum, globally defined in the Kruskal extension of the AdS black hole. We emphasize the connection of this picture with unitary SU(1,1) TFD formulation, and we show that information about the bulk and the conformal boundary is present in the SU(1,1) parameters. Using the unitary SU(1,1) TFD formulation, a canonical prescription for calculating the world sheet real time thermal Green’s function is made, and the entropy associated with the entanglement of the two CFT’s is calculated.

  7. Mobile Security Enclaves

    DTIC Science & Technology

    2011-09-01

    LAI Location Area Identity MANET Mobile Ad - hoc Network MCC Mobile Country Code MCD Mobile Communications Device MNC Mobile Network Code ...tower or present within a geographical area. These conditions relate directly to users who often operate with mobile ad - hoc networks. These types of...infrastructures. First responders can use these mobile base stations to set up their own networks on the fly, similar to mobile ad - hoc networks

  8. 42 CFR 423.2262 - Review and distribution of marketing materials.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM VOLUNTARY MEDICARE PRESCRIPTION DRUG BENEFIT Part D...) Ad hoc enrollee communication materials. Ad hoc enrollee communication materials may be reviewed by...

  9. Deconstructing tolerance with clobazam: Post hoc analyses from an open-label extension study.

    PubMed

    Gidal, Barry E; Wechsler, Robert T; Sankar, Raman; Montouris, Georgia D; White, H Steve; Cloyd, James C; Kane, Mary Clare; Peng, Guangbin; Tworek, David M; Shen, Vivienne; Isojarvi, Jouko

    2016-10-25

    To evaluate potential development of tolerance to adjunctive clobazam in patients with Lennox-Gastaut syndrome. Eligible patients enrolled in open-label extension study OV-1004, which continued until clobazam was commercially available in the United States or for a maximum of 2 years outside the United States. Enrolled patients started at 0.5 mg·kg -1 ·d -1 clobazam, not to exceed 40 mg/d. After 48 hours, dosages could be adjusted up to 2.0 mg·kg -1 ·d -1 (maximum 80 mg/d) on the basis of efficacy and tolerability. Post hoc analyses evaluated mean dosages and drop-seizure rates for the first 2 years of the open-label extension based on responder categories and baseline seizure quartiles in OV-1012. Individual patient listings were reviewed for dosage increases ≥40% and increasing seizure rates. Data from 200 patients were included. For patients free of drop seizures, there was no notable change in dosage over 24 months. For responder groups still exhibiting drop seizures, dosages were increased. Weekly drop-seizure rates for 100% and ≥75% responders demonstrated a consistent response over time. Few patients had a dosage increase ≥40% associated with an increase in seizure rates. Two-year findings suggest that the majority of patients do not develop tolerance to the antiseizure actions of clobazam. Observed dosage increases may reflect best efforts to achieve seizure freedom. It is possible that the clinical development of tolerance to clobazam has been overstated. NCT00518713 and NCT01160770. This study provides Class III evidence that the majority of patients do not develop tolerance to clobazam over 2 years of treatment. © 2016 American Academy of Neurology.

  10. The AdS3 propagator and the fate of locality

    NASA Astrophysics Data System (ADS)

    Chen, Hongbin; Fitzpatrick, A. Liam; Kaplan, Jared; Li, Daliang

    2018-04-01

    We recently used Virasoro symmetry considerations to propose an exact formula for a bulk proto-field ϕ in AdS3. In this paper we study the propagator < ϕϕ>. We show that many techniques from the study of conformal blocks can be generalized to compute it, including the semiclassical monodromy method and both forms of the Zamolodchikov recursion relations. When the results from recursion are expanded at large central charge, they match gravitational perturbation theory for a free scalar field coupled to gravity in our chosen gauge. We find that although the propagator is finite and well-defined at long distances, its perturbative expansion in {G}_N=3/2c exhibits UV/IR mixing effects. If we nevertheless interpret < ϕϕ> as a probe of bulk locality, then when {G}_{N{m}_{φ }}≪ 1 locality breaks down at the new short-distance scale {σ}_{\\ast}˜ √[4]{G_N{R}_{AdS}^3} . For ϕ with very large bulk mass, or at small central charge, bulk locality fails at the AdS length scale. In all cases, locality `breakdown' manifests as singularities or branch cuts at spacelike separation arising from non-perturbative quantum gravitational effects.

  11. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des mathematiques. Proceedings of the 1994 Annual Meeting (Regina, Saskatchewan, Canada, June 3-7, 1994).

    ERIC Educational Resources Information Center

    Quigley, Martyn, Ed.

    These proceedings contain papers from the 1994 annual meeting of the Canadian Mathematics Education Study Group. Papers are divided into the following sections: (1) invited lectures; (2) working groups; (3) topic groups; (4) ad hoc groups; and (5) reports on ICMI (International Committee on Mathematical Instruction) studies. Papers include: (1)…

  12. What's the point? Hole-ography in Poincaré AdS

    NASA Astrophysics Data System (ADS)

    Espíndola, Ricardo; Güijosa, Alberto; Landetta, Alberto; Pedraza, Juan F.

    2018-01-01

    In the context of the AdS/CFT correspondence, we study bulk reconstruction of the Poincaré wedge of AdS_3 via hole-ography, i.e., in terms of differential entropy of the dual CFT_2. Previous work had considered the reconstruction of closed or open spacelike curves in global AdS, and of infinitely extended spacelike curves in Poincaré AdS that are subject to a periodicity condition at infinity. Working first at constant time, we find that a closed curve in Poincaré is described in the CFT by a family of intervals that covers the spatial axis at least twice. We also show how to reconstruct open curves, points and distances, and obtain a CFT action whose extremization leads to bulk points. We then generalize all of these results to the case of curves that vary in time, and discover that generic curves have segments that cannot be reconstructed using the standard hole-ographic construction. This happens because, for the nonreconstructible segments, the tangent geodesics fail to be fully contained within the Poincaré wedge. We show that a previously discovered variant of the hole-ographic method allows us to overcome this challenge, by reorienting the geodesics touching the bulk curve to ensure that they all remain within the wedge. Our conclusion is that all spacelike curves in Poincaré AdS can be completely reconstructed with CFT data, and each curve has in fact an infinite number of representations within the CFT.

  13. Lurasidone for major depressive disorder with mixed features and anxiety: a post-hoc analysis of a randomized, placebo-controlled study.

    PubMed

    Tsai, Joyce; Thase, Michael E; Mao, Yongcai; Ng-Mak, Daisy; Pikalov, Andrei; Loebel, Antony

    2017-04-01

    The aim of this post-hoc analysis was to evaluate the efficacy of lurasidone in treating patients with major depressive disorder (MDD) with mixed features who present with mild and moderate-to-severe levels of anxiety. The data in this analysis were derived from a study of patients meeting the DSM-IV-TR criteria for unipolar MDD, with a Montgomery-Åsberg Depression Rating Scale (MADRS) total score ≥26, presenting with two or three protocol-defined manic symptoms, who were randomized to 6 weeks of double-blind treatment with either lurasidone 20-60 mg/day (n=109) or placebo (n=100). Anxiety severity was evaluated using the Hamilton Anxiety Rating Scale (HAM-A). To evaluate the effect of baseline anxiety on response to lurasidone, the following two anxiety groups were defined: mild anxiety (HAM-A≤14) and moderate-to-severe anxiety (HAM-A≥15). Change from baseline in MADRS total score was analyzed for each group using a mixed model for repeated measures. Treatment with lurasidone was associated with a significant week 6 change versus placebo in MADRS total score for patients with both mild anxiety (-18.4 vs. -12.8, p<0.01, effect size [ES]=0.59) and moderate-to-severe anxiety (-22.0 vs. -13.0, p<0.001, ES=0.95). Treatment with lurasidone was associated with a significant week 6 change versus placebo in HAM-A total score for patients with both mild anxiety (-7.6 vs. -4.0, p<0.01, ES=0.62), and moderate-to-severe anxiety (-11.4 vs. -6.1, p<0.0001, ES=0.91). In this post-hoc analysis of an MDD with mixed features and anxiety population, treatment with lurasidone was associated with significant improvement in both depressive and anxiety symptoms in subgroups with mild and moderate-to-severe levels of anxiety at baseline.

  14. A Decision Framework for Enhancing Mobile Ad Hoc Network Stability and Security

    DTIC Science & Technology

    2008-06-01

    www.selfless-security.org/papers/addendum.php#ivt, accessed: March 2008. [10] Berners - Lee , T., Hendler, J., and O. Lassila, "The Semantic Web," in...study under her mentorship. Professor Tim Levin consistently offered his time and expertise throughout my time at NPS. Watching and listening to...Senge, "Tests for Building Confidence in System Dynamics Models," in TIMS Studies in the Management Sciences, Vol. 14, pp. 209-228, 1980. [40

  15. Study of amyloid-β peptide functional brain networks in AD, MCI and HC.

    PubMed

    Jiang, Jiehui; Duan, Huoqiang; Huang, Zheming; Yu, Zhihua

    2015-01-01

    One medical challenge in studying the amyloid-β (Aβ) peptide mechanism for Alzheimer's disease (AD) is exploring the law of beta toxic oligomers' diffusion in human brains in vivo. One beneficial means of solving this problem is brain network analysis based on graph theory. In this study, the characteristics of Aβ functional brain networks of Healthy Control (HC), Mild Cognitive Impairment (MCI), and AD groups were compared by applying graph theoretical analyses to Carbon 11-labeled Pittsburgh compound B positron emission tomography (11C PiB-PET) data. 120 groups of PiB-PET images from the ADNI database were analyzed. The results showed that the small-world property of MCI and AD were lost as compared to HC. Furthermore, the local clustering of networks was higher in both MCI and AD as compared to HC, whereas the path length was similar among the three groups. The results also showed that there could be four potential Aβ toxic oligomer seeds: Frontal_Sup_Medial_L, Parietal_Inf_L, Frontal_Med_Orb_R, and Parietal_Inf_R. These four seeds are corresponding to Regions of Interests referred by physicians to clinically diagnose AD.

  16. Self-organized Anonymous Authentication in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Freudiger, Julien; Raya, Maxim; Hubaux, Jean-Pierre

    Pervasive communications bring along new privacy challenges, fueled by the capability of mobile devices to communicate with, and thus “sniff on”, each other directly. We design a new mechanism that aims at achieving location privacy in these forthcoming mobile networks, whereby mobile nodes collect the pseudonyms of the nodes they encounter to generate their own privacy cloaks. Thus, privacy emerges from the mobile network and users gain control over the disclosure of their locations. We call this new paradigm self-organized location privacy. In this work, we focus on the problem of self-organized anonymous authentication that is a necessary prerequisite for location privacy. We investigate, using graph theory, the optimality of different cloak constructions and evaluate with simulations the achievable anonymity in various network topologies. We show that peer-to-peer wireless communications and mobility help in the establishment of self-organized anonymous authentication in mobile networks.

  17. Mobile Ad Hoc Networks: An Evaluation of Smartphone Technologies

    DTIC Science & Technology

    2011-10-01

    National Defence, 2011 c© Sa Majesté la Reine (en droit du Canada), telle que représentée par le ministre de la Défense nationale, 2011 Abstract A...déploiement de protocoles au cours d’opérations des FC ; 4. le développement d’une implémentation de validation de principe sur un téléphone

  18. Space-Time Processing for Tactical Mobile Ad Hoc Networks

    DTIC Science & Technology

    2010-05-01

    Spatial Diversity and Imperfect Channel Estimation on Wideband MC- DS - CDMA and MC- CDMA " IEEE Transactions on Communications, Vol. 57, No. 10, pp. 2988...include direct sequence code division multiple access ( DS - CDMA ), Frequency Hopped (FH) CDMA and Orthogonal Frequency Division Multiple Access (OFDMA...capability, LPD/LPI, and operability in non-continuous spectrum. In addition, FH- CDMA is robust to the near-far problem, while DS - CDMA requires

  19. Space-Time Processing for Tactical Mobile Ad Hoc Networks

    DTIC Science & Technology

    2009-08-01

    the results for the standard 8 bits per pixel ( bpp ) 512512 Lena image [3] with a transmission rate of 0.375 bpp . To compare the image quality, we...use peak-signal-to-noise ratio (PSNR), defined as  DE 2255 log10PSNR  (dB) (2) where 255 is due to the 8 bpp image

  20. Device Discovery in Frequency Hopping Wireless Ad Hoc Networks

    DTIC Science & Technology

    2004-09-01

    10.1. Benchmark scatternet configuration used for outreach compar- ison. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 10.2. Average...Slave - Slave A B C DE Figure 10.1: Benchmark scatternet configuration used for outreach comparison. Additionally: • All nodes are within range of one...MSTSs ISOM mean = 6.97 MSTSs NISOM mean = 7.21 MSTSs Exponential distribution MSTSs P ic on et A -D p ac ke t g en er at io n ti m e pr ob ab il it y

  1. SAO/NASA ADS at SAO: ADS Browse Service

    Science.gov Websites

    Sign on [SAO/NASA ADS] ADS Browse Service ADS Home | HELP | Sitemap ADS Services Search Browse myADS Mirrors Feedback FAQ What's new Site Map Help Other NASA Centers CXC HEASARC IRSA MAST NED NSSDC -Smithsonian Center for Astrophysics [ Smithsonian logo ] The NASA Astrophysics Data System provides different

  2. Relationships in Data Sanitization: A Study in Scarlet

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bishop, Matt; Cummins, Justin; Peisert, Sean

    2010-09-23

    Data anonymization and sanitization are essential components to using and sharing data, but most approaches to performing those actions either fail to take into account all of the stakeholders, are ad hoc, or both. In this paper, we discuss a means of doing so.

  3. 75 FR 20984 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ... Mid-Atlantic Fishery Management Council's (MAFMC) Ad Hoc Search Committee will hold a closed meeting... Executive Director. The Ad Hoc Search Committee will interview candidates for this position so as to...

  4. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des mathematiques. Proceedings of the 1993 Annual Meeting (York, Ontario, Canada, May 28-June 1, 1993).

    ERIC Educational Resources Information Center

    Quigley, Martyn, Ed.

    These proceedings contain papers presented at the 1993 annual meeting of the Canadian Mathematics Education Study Group. Papers are presented in four sections: (1) invited lectures; (2) working groups; (3) topic groups; and (4) ad hoc groups. Papers include: (1) "What is a Square Root? A Study of Geometrical Representation in Different…

  5. Quality of life in Japanese women with postmenopausal osteoporosis treated with raloxifene and vitamin D: post hoc analysis of a postmarketing study.

    PubMed

    Ohta, Hiroaki; Hamaya, Etsuro; Taketsuna, Masanori; Sowa, Hideaki

    2015-01-01

    To assess the effect of active vitamin D3 on quality of life (QOL) and pain in raloxifene-treated Japanese women with postmenopausal osteoporosis. This is a post hoc analysis of a previous prospective postmarketing observational study conducted without a comparator group. This study was conducted in 60 Japanese hospitals from September 2007 to February 2009. We compared changes from baseline in QOL and pain in patients receiving raloxifene plus active vitamin D3 with those in patients receiving raloxifene monotherapy at 8 and 24 weeks after treatment. Japan Pharmaceutical Information Center (JapicCTI-070465). QOL and pain were assessed using Short Form-8 (SF-8), European Quality of Life Instrument 5 Dimensions (EQ-5D), Japanese Osteoporosis Quality of Life Questionnaire (JOQOL), visual analogue pain scales (VAS pain), and pain frequency scores. A total of 506 patients were included in the post hoc analysis. Both raloxifene monotherapy (RLX, n = 354) and active vitamin D3 cotreatment (COMBI, n = 152) significantly improved QOL and reduced pain from the baseline at Week 8 and Week 24. The COMBI group had significantly greater improvements in JOQOL total score and activity of daily living (total) domain at Week 24 and last observation carried forward (LOCF) than the RLX group. The COMBI group also had significantly greater improvements in SF-8 domains of general health (at Week 8, Week 24, and LOCF), role physical (at Week 24 and LOCF), and mental health (at LOCF) than the RLX group. The COMBI group also had significantly greater reduction in VAS pain at LOCF than the RLX group (mean [SD]: RLX = -0.99 [2.72], COMBI = -1.54 [2.21], P = 0.042). Active vitamin D3 supplementation to raloxifene treatment for 24 weeks may have additional benefits in improving QOL and relieving pain in Japanese women with postmenopausal osteoporosis.

  6. Tensionless string spectra on AdS3

    NASA Astrophysics Data System (ADS)

    Gaberdiel, Matthias R.; Gopakumar, Rajesh

    2018-05-01

    The spectrum of superstrings on AdS3 × S3 × M 4 with pure NS-NS flux is analysed for the background where the radius of the AdS space takes the minimal value ( k = 1). Both for M 4 = S3 × S1 and M 4 = T 4 we show that there is a special set of physical states, coming from the bottom of the spectrally flowed continuous representations, which agree in precise detail with the single particle spectrum of a free symmetric product orbifold. For the case of AdS3 × S3 × T 4 this relies on making sense of the world-sheet theory at k = 1, for which we make a concrete proposal. We also comment on the implications of this striking result.

  7. Training ESP Students in Corpus Use--Challenges of Using Corpus-Based Exercises with Students of Non-Philological Studies

    ERIC Educational Resources Information Center

    Marinov, Sanja

    2013-01-01

    This paper focuses on planning a series of activities to train learners of undergraduate, non-philological studies in using a small specialised ad hoc corpus and the results they achieved in doing them. The procedure discussed in this paper is a part of a larger project which investigates the possibility of using a small specialised corpus with…

  8. 78 FR 5190 - National Cancer Institute; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-24

    ... Advisory Committee; Ad hoc Clinical Trials and Strategic Planning Subcommittee. Date: February 25, 2013... Group of the Ad hoc Clinical Trials Strategic Planning Subcommittee. Dial in number: 1-866-652-9542 and...

  9. Cost study of solar cell space power systems.

    NASA Technical Reports Server (NTRS)

    Bernatowicz, D. T.

    1972-01-01

    A study of historical costs for solar cell space power systems was made by a NASA ad hoc study group. The study covered thirteen missions that represented a broad cross-section of flight projects over the past decade. Fully burdened costs in terms of 1971 dollars are presented for the system and the solar array. The costs correlate reasonably well with array area and do not increase in proportion to array area. The trends for array costs support the contention that solar cell and module standardization would reduce costs.

  10. Changes in Gait with Anteriorly Added Mass: A Pregnancy Simulation Study

    PubMed Central

    Ogamba, Maureen I.; Loverro, Kari L.; Laudicina, Natalie M.; Gill, Simone V.; Lewis, Cara L.

    2016-01-01

    During pregnancy, the female body experiences structural changes, such as weight gain. As pregnancy advances, most of the additional mass is concentrated anteriorly on the lower trunk. The purpose of this study is to analyze kinematic and kinetic changes when load is added anteriorly to the trunk, simulating a physical change experienced during pregnancy. Twenty healthy females walked on a treadmill while wearing a custom made pseudo-pregnancy sac (1 kg) under three load conditions: sac only, 10 pound condition (4.535 kg added anteriorly), and 20 pound condition (9.07 kg added anteriorly), used to simulate pregnancy, in the second trimester and at full term pregnancy, respectively. The increase in anterior mass resulted in kinematic changes at the knee, hip, pelvis, and trunk in the sagittal and frontal planes. Additionally, ankle, knee, and hip joint moments normalized to baseline mass increased with increased load; however, these moments decreased when normalized to total mass. These kinematic and kinetic changes may suggest that women modify gait biomechanics to reduce the effect of added load. Furthermore, the increase in joint moments increases stress on the musculoskeletal system and may contribute to musculoskeletal pain. PMID:26958743

  11. Quantum catastrophes: a case study

    NASA Astrophysics Data System (ADS)

    Znojil, Miloslav

    2012-11-01

    The bound-state spectrum of a Hamiltonian H is assumed real in a non-empty domain D of physical values of parameters. This means that for these parameters, H may be called crypto-Hermitian, i.e. made Hermitian via an ad hoc choice of the inner product in the physical Hilbert space of quantum bound states (i.e. via an ad hoc construction of the operator Θ called the metric). The name quantum catastrophe is then assigned to the N-tuple-exceptional-point crossing, i.e. to the scenario in which we leave the domain D along such a path that at the boundary of D, an N-plet of bound-state energies degenerates and, subsequently, complexifies. At any fixed N ⩾ 2, this process is simulated via an N × N benchmark effective matrix Hamiltonian H. It is being assigned such a closed-form metric which is made unique via an N-extrapolation-friendliness requirement. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.

  12. CycADS: an annotation database system to ease the development and update of BioCyc databases

    PubMed Central

    Vellozo, Augusto F.; Véron, Amélie S.; Baa-Puyoulet, Patrice; Huerta-Cepas, Jaime; Cottret, Ludovic; Febvay, Gérard; Calevro, Federica; Rahbé, Yvan; Douglas, Angela E.; Gabaldón, Toni; Sagot, Marie-France; Charles, Hubert; Colella, Stefano

    2011-01-01

    In recent years, genomes from an increasing number of organisms have been sequenced, but their annotation remains a time-consuming process. The BioCyc databases offer a framework for the integrated analysis of metabolic networks. The Pathway tool software suite allows the automated construction of a database starting from an annotated genome, but it requires prior integration of all annotations into a specific summary file or into a GenBank file. To allow the easy creation and update of a BioCyc database starting from the multiple genome annotation resources available over time, we have developed an ad hoc data management system that we called Cyc Annotation Database System (CycADS). CycADS is centred on a specific database model and on a set of Java programs to import, filter and export relevant information. Data from GenBank and other annotation sources (including for example: KAAS, PRIAM, Blast2GO and PhylomeDB) are collected into a database to be subsequently filtered and extracted to generate a complete annotation file. This file is then used to build an enriched BioCyc database using the PathoLogic program of Pathway Tools. The CycADS pipeline for annotation management was used to build the AcypiCyc database for the pea aphid (Acyrthosiphon pisum) whose genome was recently sequenced. The AcypiCyc database webpage includes also, for comparative analyses, two other metabolic reconstruction BioCyc databases generated using CycADS: TricaCyc for Tribolium castaneum and DromeCyc for Drosophila melanogaster. Linked to its flexible design, CycADS offers a powerful software tool for the generation and regular updating of enriched BioCyc databases. The CycADS system is particularly suited for metabolic gene annotation and network reconstruction in newly sequenced genomes. Because of the uniform annotation used for metabolic network reconstruction, CycADS is particularly useful for comparative analysis of the metabolism of different organisms. Database URL: http

  13. Post-hoc analysis of MCI186-17, the extension study to MCI186-16, the confirmatory double-blind, parallel-group, placebo-controlled study of edaravone in amyotrophic lateral sclerosis.

    PubMed

    Takahashi, Fumihiro; Takei, Koji; Tsuda, Kikumi; Palumbo, Joseph

    2017-10-01

    In the 24-week double-blind study of edaravone in ALS (MCI186-16), edaravone did not show a statistically significant difference versus placebo for the primary efficacy endpoint. For post-hoc analyses, two subpopulations were identified in which edaravone might be expected to show efficacy: the efficacy-expected subpopulation (EESP), defined by scores of ≥2 points on all 12 items of the ALS Functional Rating Scale-Revised (ALSFRS-R) and a percent predicted forced vital capacity (%FVC) ≥80% at baseline; and the definite/probable EESP 2 years (dpEESP2y) subpopulation which, in addition to EESP criteria, had definite or probable ALS diagnosed by El Escorial revised criteria, and disease duration of ≤2 years. In the 36-week extension study of MCI186-16, a 24-week double-blind comparison followed by 12 weeks of open-label edaravone (MCI186-17; NCT00424463), analyses of ALSFRS-R scores of the edaravone-edaravone group and edaravone-placebo group for the full analysis set (FAS) and EESP, as prospectively defined, were reported in a previous article. Here we additionally report results in patients who met dpEESP2y criteria at the baseline of MCI186-16. In the dpEESP2y, the difference in ALSFRS-R changes from 24 to 48 weeks between the edaravone-edaravone and edaravone-placebo groups was 2.79 (p = 0.0719), which was greater than the differences previously reported for the EESP and the FAS. The pattern of adverse events in the dpEESP2y did not show any additional safety findings to those from the earlier prospective study. In conclusion, this post-hoc analysis suggests a potential effect of edaravone between 24 and 48 weeks in patients meeting dpEESP2y criteria at baseline.

  14. Stochastic quantization of conformally coupled scalar in AdS

    NASA Astrophysics Data System (ADS)

    Jatkar, Dileep P.; Oh, Jae-Hyuk

    2013-10-01

    We explore the relation between stochastic quantization and holographic Wilsonian renormalization group flow further by studying conformally coupled scalar in AdS d+1. We establish one to one mapping between the radial flow of its double trace deformation and stochastic 2-point correlation function. This map is shown to be identical, up to a suitable field re-definition of the bulk scalar, to the original proposal in arXiv:1209.2242.

  15. Sex steroid levels and AD-like pathology in 3xTgAD mice

    PubMed Central

    Ma, Chunqi; Taves, Matthew D.; Soma, Kiran K.; Mufson, Elliott J.

    2014-01-01

    Decreases in testosterone (T) and 17β-oestradiol (E2) are associated with an increased risk for Alzheimer's disease (AD), which has been attributed to an increase in beta amyloid (Aβ) and tau pathologic lesions. While recent studies have used transgenic animal models to test the effects of sex steroid manipulations on AD-like pathology, virtually none have systematically characterised the associations between AD lesions and sex steroid levels in the blood or brain in any mutant model. The present study evaluated age-related changes in T and E2 concentrations, as well as androgen receptor (AR) and oestrogen receptor (ER) α and β expression, in brain regions displaying AD pathology in intact male and female 3xTgAD and non-transgenic (ntg) mice. We report for the first time that circulating and brain T levels significantly increase in male 3xTgAD mice with age, but without changes in AR-immunoreactive (ir) cell number in either the hippocampal CA1 or medial amygdala. The age-related increase in hippocampal T levels correlated positively with increases in the conformational tau isoform, Alz50. These data suggest that the over-expression of human tau may up regulate the hypothalamic-pituitary-gonadal axis in these mice. Although circulating and brain E2 levels remained stable with age in both male and female 3xTgAD and ntg mice, ER-ir cell number in the hippocampus and medial amygdala decreased with age in female transgenic mice. Further, E2 levels were significantly higher in the hippocampus than in serum, suggesting local production of E2. Although triple transgenic mice mimic AD-like pathology, they do not fully replicate changes in human sex steroid levels, and may not be the best model for studying the effects of sex steroids on AD lesions. PMID:22889357

  16. Half-BPS Wilson loop and AdS 2/CFT 1

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Giombi, Simone; Roiban, Radu; Tseytlin, Arkady A.

    Here, we study correlation functions of local operator insertions on the 1/2-BPS Wilson line in N=4 super Yang–Mills theory. These correlation functions are constrained by the 1d superconformal symmetry pre-served by the 1/2-BPS Wilson line and define a defect CFT 1 living on the line. At strong coupling, a set of elementary operator insertions with protected scaling dimensions correspond to fluctuations of the dual fundamental string in AdS 5×S 5 ending on the line at the boundary and can be thought of as light fields propagating on the AdS 2 worldsheet. We use AdS/CFT techniques to compute the tree-level AdSmore » 2 Witten diagrams describing the strong coupling limit of the four-point functions of the dual operator insertions. Using the OPE, we also extract the leading strong coupling corrections to the anomalous dimensions of the “two-particle” operators built out of elementary excitations. In the case of the circular Wilson loop, we match our results for the 4-point functions of a special type of scalar insertions to the prediction of localization to 2d Yang–Mills theory.« less

  17. Half-BPS Wilson loop and AdS 2/CFT 1

    DOE PAGES

    Giombi, Simone; Roiban, Radu; Tseytlin, Arkady A.

    2017-09-01

    Here, we study correlation functions of local operator insertions on the 1/2-BPS Wilson line in N=4 super Yang–Mills theory. These correlation functions are constrained by the 1d superconformal symmetry pre-served by the 1/2-BPS Wilson line and define a defect CFT 1 living on the line. At strong coupling, a set of elementary operator insertions with protected scaling dimensions correspond to fluctuations of the dual fundamental string in AdS 5×S 5 ending on the line at the boundary and can be thought of as light fields propagating on the AdS 2 worldsheet. We use AdS/CFT techniques to compute the tree-level AdSmore » 2 Witten diagrams describing the strong coupling limit of the four-point functions of the dual operator insertions. Using the OPE, we also extract the leading strong coupling corrections to the anomalous dimensions of the “two-particle” operators built out of elementary excitations. In the case of the circular Wilson loop, we match our results for the 4-point functions of a special type of scalar insertions to the prediction of localization to 2d Yang–Mills theory.« less

  18. Open string fluctuations in AdS space with and without torsion

    NASA Astrophysics Data System (ADS)

    Larsen, A. L.; Lomholt, M. A.

    2003-09-01

    The equations of motion and boundary conditions for the fluctuations around a classical open string, in a curved space-time with torsion, are considered in compact and world-sheet covariant form. The rigidly rotating open strings in anti de Sitter space with and without torsion are investigated in detail. By carefully analyzing the tangential fluctuations at the boundary, we show explicitly that the physical fluctuations (which at the boundary are combinations of normal and tangential fluctuations) are finite, even though the world-sheet is singular there. The divergent 2-curvature thus seems less dangerous than expected in these cases. The general formalism can be straightforwardly used also to study the (bosonic part of the) fluctuations around the closed strings, recently considered in connection with the AdS/conformal field theory duality, on AdS5×S5 and AdS3×S3×T4.

  19. Three Case Studies on Business Collaboration and Process Management

    ERIC Educational Resources Information Center

    Fan, Shaokun

    2012-01-01

    The importance of collaboration has been recognized for more than 2000 years. While recent improvement in technology creates vast opportunities for collaboration, effective collaboration remains challenging as ad hoc teams work across time, geographical, language, and technical boundaries, and suffer from process inefficiency. My dissertation…

  20. Value added medicines: what value repurposed medicines might bring to society?

    PubMed

    Toumi, Mondher; Rémuzat, Cécile

    2017-01-01

    Background & objectives : Despite the wide interest surrounding drug repurposing, no common terminology has been yet agreed for these products and their full potential value is not always recognised and rewarded, creating a disincentive for further development. The objectives of the present study were to assess from a wide perspective which value drug repurposing might bring to society, but also to identify key obstacles for adoption of these medicines and to discuss policy recommendations. Methods : A preliminary comprehensive search was conducted to assess how the concept of drug repurposing was described in the literature. Following completion of the literature review, a primary research was conducted to get perspective of various stakeholders across EU member states on drug repurposing ( healthcare professionals, regulatory authorities and Health Technology Assessment (HTA) bodies/payers, patients, and representatives of the pharmaceutical industry developing medicines in this field). Ad hoc literature review was performed to illustrate, when appropriate, statements of the various stakeholders. Results : Various nomenclatures have been used to describe the concept of drug repurposing in the literature, with more or less broad definitions either based on outcomes, processes, or being a mix of both. In this context, Medicines for Europe (http://www.medicinesforeurope.com/value-added-medicines/) established one single terminology for these medicines, known as value added medicines, defined as 'medicines based on known molecules that address healthcare needs and deliver relevant improvements for patients, healthcare professionals and/or payers'. Stakeholder interviews highlighted three main potential benefits for value added medicines: (1) to address a number of medicine-related healthcare inefficiencies related to irrational use of medicines, non-availability of appropriate treatment options, shortage of mature products, geographical inequity in medicine access

  1. Value added medicines: what value repurposed medicines might bring to society?

    PubMed Central

    Toumi, Mondher; Rémuzat, Cécile

    2017-01-01

    ABSTRACT Background & objectives: Despite the wide interest surrounding drug repurposing, no common terminology has been yet agreed for these products and their full potential value is not always recognised and rewarded, creating a disincentive for further development. The objectives of the present study were to assess from a wide perspective which value drug repurposing might bring to society, but also to identify key obstacles for adoption of these medicines and to discuss policy recommendations. Methods: A preliminary comprehensive search was conducted to assess how the concept of drug repurposing was described in the literature. Following completion of the literature review, a primary research was conducted to get perspective of various stakeholders across EU member states on drug repurposing (healthcare professionals, regulatory authorities and Health Technology Assessment (HTA) bodies/payers, patients, and representatives of the pharmaceutical industry developing medicines in this field). Ad hoc literature review was performed to illustrate, when appropriate, statements of the various stakeholders. Results: Various nomenclatures have been used to describe the concept of drug repurposing in the literature, with more or less broad definitions either based on outcomes, processes, or being a mix of both. In this context, Medicines for Europe (http://www.medicinesforeurope.com/value-added-medicines/) established one single terminology for these medicines, known as value added medicines, defined as ‘medicines based on known molecules that address healthcare needs and deliver relevant improvements for patients, healthcare professionals and/or payers’. Stakeholder interviews highlighted three main potential benefits for value added medicines: (1) to address a number of medicine-related healthcare inefficiencies related to irrational use of medicines, non-availability of appropriate treatment options, shortage of mature products, geographical inequity in medicine

  2. The Land Warrior Soldier System: A Case Study for the Acquisition of Soldier Systems

    DTIC Science & Technology

    2008-12-01

    demonstration projects (Montgomery, Godden, LaBerge & Wagner, 1994). The ASB ad-hoc study found that the then-recent SIPE demonstrations offered...Personal Navigation” by Peter Sherman and Steven Holmes, Draper Laboratory, Cambridge, Massachusetts, October 2005. U.S. Army Research Institute for...8217 perspective. [Interview with researchers]. Haley, R. L., Campbell, C. C., Holter, M. R., Shields, J., Godden, G. D., & LaBerge , W. B. (1991, December). Army

  3. F-theory and AdS3/CFT2 (2, 0)

    NASA Astrophysics Data System (ADS)

    Couzens, Christopher; Martelli, Dario; Schäfer-Nameki, Sakura

    2018-06-01

    We continue to develop the program initiated in [1] of studying supersymmetric AdS3 backgrounds of F-theory and their holographic dual 2d superconformal field theories, which are dimensional reductions of theories with varying coupling. Imposing 2d N=(0,2) supersymmetry,wederivethegeneralconditionsonthegeometryforTypeIIB AdS3 solutions with varying axio-dilaton and five-form flux. Locally the compact part of spacetime takes the form of a circle fibration over an eight-fold Y_8^{τ } , which is elliptically fibered over a base \\tilde{M}_6 . We construct two classes of solutions given in terms of a product ansatz \\tilde{M}_6}=Σ × {M}_4 , where Σ is a complex curve and \\tilde{M}_4 is locally a Kähler surface. In the first class \\tilde{M}_4 is globally a Kähler surface and we take the elliptic fibration to vary non-trivially over either of these two factors, where in both cases the metrics on the total space of the elliptic fibrations are not Ricci-flat. In the second class the metric on the total space of the elliptic fibration over either curve or surface are Ricci-flat. This results in solutions of the type AdS3 × K3 × ℳ 5 τ , dual to 2d (0, 2) SCFTs, and AdS3 × S 3/Γ × CY 3, dual to 2d (0, 4) SCFTs, respectively. In all cases we compute the charges for the dual field theories with varying coupling and find agreement with the holographic results. We also show that solutions with enhanced 2d N=(2,2) supersymmetry must have constant axio-dilaton. Allowing the internal geometry to be non-compact leads to the most general class of Type IIB AdS5 solutions with varying axio-dilaton, i.e. F-theoretic solutions, that are dual to 4d N=1 SCFTs.

  4. AdS7/CFT6 with orientifolds

    NASA Astrophysics Data System (ADS)

    Apruzzi, Fabio; Fazzi, Marco

    2018-01-01

    AdS7 solutions of massive type IIA have been classified, and are dual to a large class of six-dimensional (1, 0) SCFT's whose tensor branch deformations are described by linear quivers of SU groups. Quivers and AdS vacua depend solely on the group theory data of the NS5-D6-D8 brane configurations engineering the field theories. This has allowed for a direct holographic match of their a conformal anomaly. In this paper we extend the match to cases where O6 and O8-planes are present, thereby introducing SO and USp groups in the quivers. In all of them we show that the a anomaly computed in supergravity agrees with the holographic limit of the exact field theory result, which we extract from the anomaly polynomial. As a byproduct we construct special AdS7 vacua dual to nonperturbative F-theory configurations. Finally, we propose a holographic a-theorem for six-dimensional Higgs branch RG flows.

  5. Massive quiver matrix models for massive charged particles in AdS

    DOE PAGES

    Asplund, Curtis T.; Denef, Frederik; Dzienkowski, Eric

    2016-01-11

    Here, we present a new class of N = 4 supersymmetric quiver matrix models and argue that it describes the stringy low-energy dynamics of internally wrapped D-branes in four-dimensional anti-de Sitter (AdS) flux compactifications. The Lagrangians of these models differ from previously studied quiver matrix models by the presence of mass terms, associated with the AdS gravitational potential, as well as additional terms dictated by supersymmetry. These give rise to dynamical phenomena typically associated with the presence of fluxes, such as fuzzy membranes, internal cyclotron motion and the appearance of confining strings. We also show how these models can bemore » obtained by dimensional reduction of four-dimensional supersymmetric quiver gauge theories on a three-sphere.« less

  6. Functional determinants of radial operators in AdS2

    DOE PAGES

    Aguilera-Damia, Jeremías; Faraggi, Alberto; Zayas, Leopoldo Pando; ...

    2018-06-01

    We study the zeta-function regularization of functional determinants of Laplace and Dirac-type operators in two-dimensional Euclidean AdS2 space. More specifically, we consider the ratio of determinants between an operator in the presence of background fields with circular symmetry and the free operator in which the background fields are absent. By Fourier-transforming the angular dependence, one obtains an infinite number of one-dimensional radial operators, the determinants of which are easy to compute. The summation over modes is then treated with care so as to guarantee that the result coincides with the two-dimensional zeta-function formalism. The method relies on some well-known techniquesmore » to compute functional determinants using contour integrals and the construction of the Jost function from scattering theory. Our work generalizes some known results in flat space. The extension to conformal AdS2 geometries is also considered. We provide two examples, one bosonic and one fermionic, borrowed from the spectrum of fluctuations of the holographic 1/4-BPS latitude Wilson loop.« less

  7. Functional determinants of radial operators in AdS 2

    NASA Astrophysics Data System (ADS)

    Aguilera-Damia, Jeremías; Faraggi, Alberto; Zayas, Leopoldo Pando; Rathee, Vimal; Silva, Guillermo A.

    2018-06-01

    We study the zeta-function regularization of functional determinants of Laplace and Dirac-type operators in two-dimensional Euclidean AdS 2 space. More specifically, we consider the ratio of determinants between an operator in the presence of background fields with circular symmetry and the free operator in which the background fields are absent. By Fourier-transforming the angular dependence, one obtains an infinite number of one-dimensional radial operators, the determinants of which are easy to compute. The summation over modes is then treated with care so as to guarantee that the result coincides with the two-dimensional zeta-function formalism. The method relies on some well-known techniques to compute functional determinants using contour integrals and the construction of the Jost function from scattering theory. Our work generalizes some known results in flat space. The extension to conformal AdS 2 geometries is also considered. We provide two examples, one bosonic and one fermionic, borrowed from the spectrum of fluctuations of the holographic 1/4 -BPS latitude Wilson loop.

  8. Multigrid method based on the transformation-free HOC scheme on nonuniform grids for 2D convection diffusion problems

    NASA Astrophysics Data System (ADS)

    Ge, Yongbin; Cao, Fujun

    2011-05-01

    In this paper, a multigrid method based on the high order compact (HOC) difference scheme on nonuniform grids, which has been proposed by Kalita et al. [J.C. Kalita, A.K. Dass, D.C. Dalal, A transformation-free HOC scheme for steady convection-diffusion on non-uniform grids, Int. J. Numer. Methods Fluids 44 (2004) 33-53], is proposed to solve the two-dimensional (2D) convection diffusion equation. The HOC scheme is not involved in any grid transformation to map the nonuniform grids to uniform grids, consequently, the multigrid method is brand-new for solving the discrete system arising from the difference equation on nonuniform grids. The corresponding multigrid projection and interpolation operators are constructed by the area ratio. Some boundary layer and local singularity problems are used to demonstrate the superiority of the present method. Numerical results show that the multigrid method with the HOC scheme on nonuniform grids almost gets as equally efficient convergence rate as on uniform grids and the computed solution on nonuniform grids retains fourth order accuracy while on uniform grids just gets very poor solution for very steep boundary layer or high local singularity problems. The present method is also applied to solve the 2D incompressible Navier-Stokes equations using the stream function-vorticity formulation and the numerical solutions of the lid-driven cavity flow problem are obtained and compared with solutions available in the literature.

  9. New massive gravity and AdS(4) counterterms.

    PubMed

    Jatkar, Dileep P; Sinha, Aninda

    2011-04-29

    We show that the recently proposed Dirac-Born-Infeld extension of new massive gravity emerges naturally as a counterterm in four-dimensional anti-de Sitter space (AdS(4)). The resulting on-shell Euclidean action is independent of the cutoff at zero temperature. We also find that the same choice of counterterm gives the usual area law for the AdS(4) Schwarzschild black hole entropy in a cutoff-independent manner. The parameter values of the resulting counterterm action correspond to a c=0 theory in the context of the duality between AdS(3) gravity and two-dimensional conformal field theory. We rewrite this theory in terms of the gauge field that is used to recast 3D gravity as a Chern-Simons theory.

  10. Small black holes in global AdS spacetime

    NASA Astrophysics Data System (ADS)

    Jokela, Niko; Pönni, Arttu; Vuorinen, Aleksi

    2016-04-01

    We study the properties of two-point functions and quasinormal modes in a strongly coupled field theory holographically dual to a small black hole in global anti-de Sitter spacetime. Our results are seen to smoothly interpolate between known limits corresponding to large black holes and thermal AdS space, demonstrating that the Son-Starinets prescription works even when there is no black hole in the spacetime. Omitting issues related to the internal space, the results can be given a field theory interpretation in terms of the microcanonical ensemble, which provides access to energy densities forbidden in the canonical description.

  11. Euclidean Wilson loops and minimal area surfaces in lorentzian AdS 3

    DOE PAGES

    Irrgang, Andrew; Kruczenski, Martin

    2015-12-14

    The AdS/CFT correspondence relates Wilson loops in N=4 SYM theory to minimal area surfaces in AdS 5 × S 5 space. If the Wilson loop is Euclidean and confined to a plane (t, x) then the dual surface is Euclidean and lives in Lorentzian AdS 3 c AdS 5. In this paper we study such minimal area surfaces generalizing previous results obtained in the Euclidean case. Since the surfaces we consider have the topology of a disk, the holonomy of the flat current vanishes which is equivalent to the condition that a certain boundary Schrödinger equation has all its solutionsmore » anti-periodic. If the potential for that Schrödinger equation is found then reconstructing the surface and finding the area become simpler. In particular we write a formula for the Area in terms of the Schwarzian derivative of the contour. Finally an infinite parameter family of analytical solutions using Riemann Theta functions is described. In this case, both the area and the shape of the surface are given analytically and used to check the previous results.« less

  12. Exposure to movie smoking, antismoking ads and smoking intensity: an experimental study with a factorial design.

    PubMed

    Harakeh, Zeena; Engels, Rutger C M E; Vohs, Kathleen; van Baaren, Rick B; Sargent, James

    2010-06-01

    This study examines whether smoking portrayal in movies or antismoking advertisements affect smoking intensity among young adults. We conducted an experimental study in which 84 smokers were randomly assigned using a two (no-smoking versus smoking portrayal in the movie) by three (two prosocial ads, two antismoking ads or one of each) factorial design. Participants viewed a 60-minute movie with two commercial breaks and afterwards completed a questionnaire. Smoking during the session was allowed and observed. Exposure to the movie with smoking had no effect on smoking intensity. Those who viewed two antismoking ads had significantly lower smoking intensity compared with those who viewed two prosocial ads. There was no interaction between movie smoking and antismoking ads. Baseline CO (carbon monoxide) level had the largest effect on smoking intensity. These findings provide further evidence to support antismoking ads placed with movies because of their possible effect on young adult smoking behaviour. However, caution is warranted, because nicotine dependence appears to be the primary predictor of smoking intensity among young adult smokers in this study.

  13. Exposure to movie smoking, antismoking ads and smoking intensity: an experimental study with a factorial design

    PubMed Central

    Harakeh, Zeena; Engels, Rutger C M E; Vohs, Kathleen; van Baaren, Rick B; Sargent, James

    2013-01-01

    Background This study examines whether smoking portrayal in movies or antismoking advertisements affect smoking intensity among young adults. Methods We conducted an experimental study in which 84 smokers were randomly assigned using a two (no-smoking versus smoking portrayal in the movie) by three (two prosocial ads, two antismoking ads or one of each) factorial design. Participants viewed a 60-minute movie with two commercial breaks and afterwards completed a questionnaire. Smoking during the session was allowed and observed. Results Exposure to the movie with smoking had no effect on smoking intensity. Those who viewed two antismoking ads had significantly lower smoking intensity compared with those who viewed two prosocial ads. There was no interaction between movie smoking and antismoking ads. Baseline CO (carbon monoxide) level had the largest effect on smoking intensity. Conclusion These findings provide further evidence to support antismoking ads placed with movies because of their possible effect on young adult smoking behaviour. However, caution is warranted, because nicotine dependence appears to be the primary predictor of smoking intensity among young adult smokers in this study. PMID:20008155

  14. Post Hoc Analyses of Randomized Clinical Trial for the Effect of Clopidogrel Added to Aspirin on Kidney Function.

    PubMed

    Ikeme, Jesse C; Pergola, Pablo E; Scherzer, Rebecca; Shlipak, Michael G; Benavente, Oscar R; Peralta, Carmen A

    2017-07-07

    Despite the high burden of CKD, few specific therapies are available that can halt disease progression. In animal models, clopidogrel has emerged as a potential therapy to preserve kidney function. The effect of clopidogrel on kidney function in humans has not been established. The Secondary Prevention of Small Subcortical Strokes Study randomized participants with prior lacunar stroke to treatment with aspirin or aspirin plus clopidogrel. We compared annual eGFR decline and incidence of rapid eGFR decline (≥30% from baseline) using generalized estimating equations and interval-censored proportional hazards regression, respectively. We also stratified our analyses by baseline eGFR, systolic BP target, and time after randomization. At randomization, median age was 62 (interquartile range, 55-71) years old; 36% had a history of diabetes, 90% had hypertension, and the median eGFR was 81 (interquartile range, 65-94) ml/min per 1 m 2 . Persons receiving aspirin plus clopidogrel had an average annual change in kidney function of -1.39 (95% confidence interval, -1.15 to -1.62) ml/min per 1.73 m 2 per year compared with -1.52 (95% confidence interval, -1.30 to -1.74) ml/min per 1.73 m 2 per year among persons receiving aspirin only ( P =0.42). Rapid kidney function decline occurred in 21% of participants receiving clopidogrel plus aspirin compared with 22% of participants receiving aspirin plus placebo (hazard ratio, 0.94; 95% confidence interval, 0.79 to 1.10; P =0.42). Findings did not vary by baseline eGFR, time after randomization, or systolic BP target (all P values for interaction were >0.3). We found no effect of clopidogrel added to aspirin compared with aspirin alone on kidney function decline among persons with prior lacunar stroke. Copyright © 2017 by the American Society of Nephrology.

  15. Boundary stress tensor and asymptotically AdS3 non-Einstein spaces at the chiral point

    NASA Astrophysics Data System (ADS)

    Giribet, Gaston; Goya, Andrés; Leston, Mauricio

    2011-09-01

    Chiral gravity admits asymptotically AdS3 solutions that are not locally equivalent to AdS3; meaning that solutions do exist which, while obeying the strong boundary conditions usually imposed in general relativity, happen not to be Einstein spaces. In topologically massive gravity (TMG), the existence of non-Einstein solutions is particularly connected to the question about the role played by complex saddle points in the Euclidean path integral. Consequently, studying (the existence of) nonlocally AdS3 solutions to chiral gravity is relevant to understanding the quantum theory. Here, we discuss a special family of nonlocally AdS3 solutions to chiral gravity. In particular, we show that such solutions persist when one deforms the theory by adding the higher-curvature terms of the so-called new massive gravity. Moreover, the addition of higher-curvature terms to the gravity action introduces new nonlocally AdS3 solutions that have no analogues in TMG. Both stationary and time-dependent, axially symmetric solutions that asymptote AdS3 space without being locally equivalent to it appear. Defining the boundary stress tensor for the full theory, we show that these non-Einstein geometries have associated vanishing conserved charges.

  16. Making great leaps forward: Accounting for detectability in herpetological field studies

    USGS Publications Warehouse

    Mazerolle, Marc J.; Bailey, Larissa L.; Kendall, William L.; Royle, J. Andrew; Converse, Sarah J.; Nichols, James D.

    2007-01-01

    Detecting individuals of amphibian and reptile species can be a daunting task. Detection can be hindered by various factors such as cryptic behavior, color patterns, or observer experience. These factors complicate the estimation of state variables of interest (e.g., abundance, occupancy, species richness) as well as the vital rates that induce changes in these state variables (e.g., survival probabilities for abundance; extinction probabilities for occupancy). Although ad hoc methods (e.g., counts uncorrected for detection, return rates) typically perform poorly in the face of no detection, they continue to be used extensively in various fields, including herpetology. However, formal approaches that estimate and account for the probability of detection, such as capture-mark-recapture (CMR) methods and distance sampling, are available. In this paper, we present classical approaches and recent advances in methods accounting for detectability that are particularly pertinent for herpetological data sets. Through examples, we illustrate the use of several methods, discuss their performance compared to that of ad hoc methods, and we suggest available software to perform these analyses. The methods we discuss control for imperfect detection and reduce bias in estimates of demographic parameters such as population size, survival, or, at other levels of biological organization, species occurrence. Among these methods, recently developed approaches that no longer require marked or resighted individuals should be particularly of interest to field herpetologists. We hope that our effort will encourage practitioners to implement some of the estimation methods presented herein instead of relying on ad hoc methods that make more limiting assumptions.

  17. 78 FR 47675 - Pacific Fishery Management Council; Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-06

    ... Pacific Fishery Management Council's (Pacific Council) Ad Hoc Groundfish Electronic Monitoring Committee and Ad Hoc Trawl Groundfish Electronic Monitoring Technical Advisory Committee (GEM Committees) will... meeting is to discuss and develop potential alternatives for electronic monitoring (EM) for vessels...

  18. Stable nitrogen isotope ratios and accumulation of various HOCs in northern Baltic aquatic food chains

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Broman, D.; Axelman, J.; Bergqvist, P.A.

    Ratios of naturally occurring stable isotopes of nitrogen ({delta}{sup 15}N) can be used to numerically classify trophic levels of organisms in food chains. By combining analyses results of various HOCs (e.g. PCDD/Fs, PCBs, DDTs, HCHs and some other pesticides) the biomagnification of these substances can be quantitatively estimated. In this paper different pelagic and benthic northern Baltic food chains were studied. The {delta}{sup 15}N-data gave food chain descriptions qualitatively consistent with previous conceptions of trophic arrangements in the food chains. The different HOCs concentrations were plotted versus the {delta}{sup 15}N-values for the different trophic levels and an exponential model ofmore » the form e{sup (A+B*{delta}N)} was fitted to the data. The estimates of the constant B in the model allows for an estimation of a biomagnification power (B) of different singular, or groups of, contaminants. A B-value around zero indicates that a substance is flowing through the food chain without being magnified, whereas a value > 0 indicates that a substance is biomagnified. Negative B-values indicate that a substance is not taken up or is metabolized. The A-term of the expression is only a scaling factor depending on the background level of the contaminant.« less

  19. Loops in AdS from conformal field theory

    DOE PAGES

    Aharony, Ofer; Alday, Luis F.; Bissi, Agnese; ...

    2017-07-10

    We propose and demonstrate a new use for conformal field theory (CFT) crossing equations in the context of AdS/CFT: the computation of loop amplitudes in AdS, dual to non-planar correlators in holographic CFTs. Loops in AdS are largely unexplored, mostly due to technical difficulties in direct calculations. We revisit this problem, and the dual 1=N expansion of CFTs, in two independent ways. The first is to show how to explicitly solve the crossing equations to the first subleading order in 1=N 2, given a leading order solution. This is done as a systematic expansion in inverse powers of the spin, to all orders. These expansions can be resummed, leading to the CFT data for nite values of the spin. Our second approach involves Mellin space. We show how the polar part of the four-point, loop-level Mellin amplitudes can be fully reconstructed from the leading-order data. The anomalous dimensions computed with both methods agree. In the case ofmore » $$\\phi$$ 4 theory in AdS, our crossing solution reproduces a previous computation of the one-loop bubble diagram. We can go further, deriving the four-point scalar triangle diagram in AdS, which had never been computed. In the process, we show how to analytically derive anomalous dimensions from Mellin amplitudes with an in nite series of poles, and discuss applications to more complicated cases such as the N = 4 super-Yang-Mills theory.« less

  20. Loops in AdS from conformal field theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aharony, Ofer; Alday, Luis F.; Bissi, Agnese

    We propose and demonstrate a new use for conformal field theory (CFT) crossing equations in the context of AdS/CFT: the computation of loop amplitudes in AdS, dual to non-planar correlators in holographic CFTs. Loops in AdS are largely unexplored, mostly due to technical difficulties in direct calculations. We revisit this problem, and the dual 1=N expansion of CFTs, in two independent ways. The first is to show how to explicitly solve the crossing equations to the first subleading order in 1=N 2, given a leading order solution. This is done as a systematic expansion in inverse powers of the spin, to all orders. These expansions can be resummed, leading to the CFT data for nite values of the spin. Our second approach involves Mellin space. We show how the polar part of the four-point, loop-level Mellin amplitudes can be fully reconstructed from the leading-order data. The anomalous dimensions computed with both methods agree. In the case ofmore » $$\\phi$$ 4 theory in AdS, our crossing solution reproduces a previous computation of the one-loop bubble diagram. We can go further, deriving the four-point scalar triangle diagram in AdS, which had never been computed. In the process, we show how to analytically derive anomalous dimensions from Mellin amplitudes with an in nite series of poles, and discuss applications to more complicated cases such as the N = 4 super-Yang-Mills theory.« less

  1. Loops in AdS from conformal field theory

    NASA Astrophysics Data System (ADS)

    Aharony, Ofer; Alday, Luis F.; Bissi, Agnese; Perlmutter, Eric

    2017-07-01

    We propose and demonstrate a new use for conformal field theory (CFT) crossing equations in the context of AdS/CFT: the computation of loop amplitudes in AdS, dual to non-planar correlators in holographic CFTs. Loops in AdS are largely unexplored, mostly due to technical difficulties in direct calculations. We revisit this problem, and the dual 1 /N expansion of CFTs, in two independent ways. The first is to show how to explicitly solve the crossing equations to the first subleading order in 1 /N 2, given a leading order solution. This is done as a systematic expansion in inverse powers of the spin, to all orders. These expansions can be resummed, leading to the CFT data for finite values of the spin. Our second approach involves Mellin space. We show how the polar part of the four-point, loop-level Mellin amplitudes can be fully reconstructed from the leading-order data. The anomalous dimensions computed with both methods agree. In the case of ϕ 4 theory in AdS, our crossing solution reproduces a previous computation of the one-loop bubble diagram. We can go further, deriving the four-point scalar triangle diagram in AdS, which had never been computed. In the process, we show how to analytically derive anomalous dimensions from Mellin amplitudes with an infinite series of poles, and discuss applications to more complicated cases such as the N = 4 super-Yang-Mills theory.

  2. Worldsheet scattering in AdS3/CFT2

    NASA Astrophysics Data System (ADS)

    Sundin, Per; Wulff, Linus

    2013-07-01

    We confront the recently proposed exact S-matrices for AdS 3/ CFT 2 with direct worldsheet calculations. Utilizing the BMN and Near Flat Space (NFS) expansions for strings on AdS 3 × S 3 × S 3 × S 1 and AdS 3 × S 3 × T 4 we compute both tree-level and one-loop scattering amplitudes. Up to some minor issues we find nice agreement in the tree-level sector. At the one-loop level however we find that certain non-zero tree-level processes, which are not visible in the exact solution, contribute, via the optical theorem, and give an apparent mismatch for certain amplitudes. Furthermore we find that a proposed one-loop modification of the dressing phase correctly reproduces the worldsheet calculation while the standard Hernandez-Lopez phase does not. We also compute several massless to massless processes.

  3. 17 CFR 240.17Ad-13 - Annual study and evaluation of internal accounting control.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Annual study and evaluation of internal accounting control. 240.17Ad-13 Section 240.17Ad-13 Commodity and Securities Exchanges SECURITIES... System, the Office of the Comptroller of the Currency or the Federal Deposit Insurance Corporation...

  4. Early identification of MCI converting to AD: a FDG PET study.

    PubMed

    Pagani, Marco; Nobili, Flavio; Morbelli, Silvia; Arnaldi, Dario; Giuliani, Alessandro; Öberg, Johanna; Girtler, Nicola; Brugnolo, Andrea; Picco, Agnese; Bauckneht, Matteo; Piva, Roberta; Chincarini, Andrea; Sambuceti, Gianmario; Jonsson, Cathrine; De Carli, Fabrizio

    2017-11-01

    Mild cognitive impairment (MCI) is a transitional pathological stage between normal ageing (NA) and Alzheimer's disease (AD). Although subjects with MCI show a decline at different rates, some individuals remain stable or even show an improvement in their cognitive level after some years. We assessed the accuracy of FDG PET in discriminating MCI patients who converted to AD from those who did not. FDG PET was performed in 42 NA subjects, 27 MCI patients who had not converted to AD at 5 years (nc-MCI; mean follow-up time 7.5 ± 1.5 years), and 95 MCI patients who converted to AD within 5 years (MCI-AD; mean conversion time 1.8 ± 1.1 years). Relative FDG uptake values in 26 meta-volumes of interest were submitted to ANCOVA and support vector machine analyses to evaluate regional differences and discrimination accuracy. The MCI-AD group showed significantly lower FDG uptake values in the temporoparietal cortex than the other two groups. FDG uptake values in the nc-MCI group were similar to those in the NA group. Support vector machine analysis discriminated nc-MCI from MCI-AD patients with an accuracy of 89% (AUC 0.91), correctly detecting 93% of the nc-MCI patients. In MCI patients not converting to AD within a minimum follow-up time of 5 years and MCI patients converting within 5 years, baseline FDG PET and volume-based analysis identified those who converted with an accuracy of 89%. However, further analysis is needed in patients with amnestic MCI who convert to a dementia other than AD.

  5. Topological terms, AdS2 n gravity, and renormalized entanglement entropy of holographic CFTs

    NASA Astrophysics Data System (ADS)

    Anastasiou, Giorgos; Araya, Ignacio J.; Olea, Rodrigo

    2018-05-01

    We extend our topological renormalization scheme for entanglement entropy to holographic CFTs of arbitrary odd dimensions in the context of the AdS /CFT correspondence. The procedure consists in adding the Chern form as a boundary term to the area functional of the Ryu-Takayanagi minimal surface. The renormalized entanglement entropy thus obtained can be rewritten in terms of the Euler characteristic and the AdS curvature of the minimal surface. This prescription considers the use of the replica trick to express the renormalized entanglement entropy in terms of the renormalized gravitational action evaluated on the conically singular replica manifold extended to the bulk. This renormalized action is obtained in turn by adding the Chern form as the counterterm at the boundary of the 2 n -dimensional asymptotically AdS bulk manifold. We explicitly show that, up to next-to-leading order in the holographic radial coordinate, the addition of this boundary term cancels the divergent part of the entanglement entropy. We discuss possible applications of the method for studying CFT parameters like central charges.

  6. The Nun study: clinically silent AD, neuronal hypertrophy, and linguistic skills in early life.

    PubMed

    Iacono, D; Markesbery, W R; Gross, M; Pletnikova, O; Rudow, G; Zandi, P; Troncoso, J C

    2009-09-01

    It is common to find substantial Alzheimer disease (AD) lesions, i.e., neuritic beta-amyloid plaques and neurofibrillary tangles, in the autopsied brains of elderly subjects with normal cognition assessed shortly before death. We have termed this status asymptomatic AD (ASYMAD). We assessed the morphologic substrate of ASYMAD compared to mild cognitive impairment (MCI) in subjects from the Nun Study. In addition, possible correlations between linguistic abilities in early life and the presence of AD pathology with and without clinical manifestations in late life were considered. Design-based stereology was used to measure the volumes of neuronal cell bodies, nuclei, and nucleoli in the CA1 region of hippocampus (CA1). Four groups of subjects were compared: ASYMAD (n = 10), MCI (n = 5), AD (n = 10), and age-matched controls (n = 13). Linguistic ability assessed in early life was compared among all groups. A significant hypertrophy of the cell bodies (+44.9%), nuclei (+59.7%), and nucleoli (+80.2%) in the CA1 neurons was found in ASYMAD compared with MCI. Similar differences were observed with controls. Furthermore, significant higher idea density scores in early life were observed in controls and ASYMAD group compared to MCI and AD groups. 1) Neuronal hypertrophy may constitute an early cellular response to Alzheimer disease (AD) pathology or reflect compensatory mechanisms that prevent cognitive impairment despite substantial AD lesions; 2) higher idea density scores in early life are associated with intact cognition in late life despite the presence of AD lesions.

  7. The generalization of charged AdS black hole specific volume and number density

    NASA Astrophysics Data System (ADS)

    Wang, Zi-Liang; He, Miao; Fang, Chao; Sun, Dao-Quan; Deng, Jian-Bo

    2017-04-01

    In this paper, by proposing a generalized specific volume, we restudy the P- V criticality of charged AdS black holes in the extended phase space. The results show that most of the previous conclusions can be generalized without change, but the ratio {\\tilde{ρ }}_c should be 3 {\\tilde{α }}/16 in general case. Further research on the thermodynamical phase transition of black hole leads us to a natural interpretation of our assumption, and more black hole properties can be generalized. Finally, we study the number density for charged AdS black hole in higher dimensions, the results show the necessity of our assumption.

  8. A Study on New Pochonka Published in A.D. 1792

    NASA Astrophysics Data System (ADS)

    Ahn, Sang-Hyeon

    2009-12-01

    New Pochonka published in the eighteenth century of the Choson dynasty was composed of star-charts based on the new observations made by Jesuits in China and songs corrected a little bit from previous version of Pochonka. The asterisms in the previous Pochonka are listed in the same order to that in the Song dynasty's literature; while the asterisms in the new Pochonka are listed in accordance with Pu-tien-ko published in China after the Ming dynasty. The Chinese-style twelve-equatorial-section system is adopted in the new Pochonka, while in its song is adopted the zodiac system, which can be seen in the star-charts of previous version of Pochonka. The asterisms belonging to three or four neighboring lunar-mansions are drawn in one chart. Each chart covers asterisms not belonging to a certain range of right ascension, but to a certain lunar mansion. We estimate the forming era of the new Pochonka from the following facts; that the Ling-Tai-I-Hsiang-Chih was used to make charts and footnotes whose archetype can be found in the Chinese literature around A.D. 1700, that these Chinese books were imported into Choson in A.D. 1709, that the naming taboo to the emperor Khang-Hsi was used, that the order of Shen-Hsiu (參宿) was transposed with Tshui-Hsiu (자宿), and that the new Pochonka was substituted for the old version when the rules of Royal Astronomical Bureau was reformed in A.D. 1791. In conclusion, the parent sources of the charts and footnotes of the new Pochonka might be imported from the Ching dynasty around 1709 A.D. to form the new Pochonka between A.D. 1709 and A.D. 1791, and finally to be published in A.D. 1792. We discuss the possible future works to make a firm conclusion.

  9. Efficient routing for safety applications in vehicular networks.

    DOT National Transportation Integrated Search

    2009-03-01

    Vehicular ad hoc networks have received a lot of attention in recent years. This attention is due to two reasons. : First and foremost, there are a number of real-life applications that become possible in the presence of : such an ad-hoc infrastructu...

  10. Rotigotine in Combination with the MAO-B Inhibitor Selegiline in Early Parkinson's Disease: A Post Hoc Analysis.

    PubMed

    Giladi, Nir; Asgharnejad, Mahnaz; Bauer, Lars; Grieger, Frank; Boroojerdi, Babak

    2016-04-02

    Monoamine oxidase B (MAO-B) inhibitors and dopamine receptor agonists are common first-line treatment options in early Parkinson's disease (PD). To evaluate the efficacy and safety of rotigotine transdermal patch as an add-on therapy to an MAO-B inhibitor in patients with early-PD. In two Phase III, randomized, double-blind, placebo-controlled studies in early-PD (SP512, SP513), patients were randomized to rotigotine (titrated to optimal dose ≤8 mg/24 h) or placebo, and maintained for 24 (SP512) or 33 (SP513) weeks. Post hoc analyses were performed on pooled data for patients receiving an MAO-B inhibitor (selegiline) at a stable dose at randomization and throughout the studies, with groups defined as "Selegiline+Rotigotine" and "Selegiline+Placebo". Outcome measures included change from baseline in Unified Parkinson's Disease Rating Scale (UPDRS) II (activities of daily living), III (motor), UPDRS II+III and responders (patients achieving ≥20%, ≥25% or ≥30% decrease in UPDRS II+III). As post hoc analyses, p-values are exploratory. 130 patients were evaluable for efficacy analyses ("Selegiline+Rotigotine": 84, "Selegiline+Placebo": 46). Combined treatment with rotigotine and selegiline improved UPDRS III and UPDRS II+III scores versus selegiline alone (LS-mean [95% CI] treatment difference for UPDRS III: -4.89 [-7.87 to -1.91], p = 0.0015; for UPDRS II+III: -5.76 [-9.71 to -1.82], p = 0.0045). Higher proportion of patients in the "Selegiline+Rotigotine" group were classified as ≥20%, ≥25% or ≥30% responders (all p < 0.001). Combined treatment appeared more effective in patients aged ≤65 years versus > 65 years (although patient numbers in the subgroups were low). Adverse event profile was consistent with the known safety profile of rotigotine. In these post hoc analyses, adjunctive treatment with rotigotine in patients already receiving an MAO-B inhibitor improved UPDRS II+III score; this appeared to be largely driven by

  11. 17 CFR 240.17Ad-13 - Annual study and evaluation of internal accounting control.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Annual study and evaluation of internal accounting control. 240.17Ad-13 Section 240.17Ad-13 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under the Securities...

  12. 17 CFR 240.17Ad-13 - Annual study and evaluation of internal accounting control.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Annual study and evaluation of internal accounting control. 240.17Ad-13 Section 240.17Ad-13 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under the Securities...

  13. 17 CFR 240.17Ad-13 - Annual study and evaluation of internal accounting control.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Annual study and evaluation of internal accounting control. 240.17Ad-13 Section 240.17Ad-13 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under the Securities...

  14. 17 CFR 240.17Ad-13 - Annual study and evaluation of internal accounting control.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Annual study and evaluation of internal accounting control. 240.17Ad-13 Section 240.17Ad-13 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under the Securities...

  15. Holography in Lovelock Chern-Simons AdS gravity

    NASA Astrophysics Data System (ADS)

    Cvetković, Branislav; Miskovic, Olivera; Simić, Dejan

    2017-08-01

    We analyze holographic field theory dual to Lovelock Chern-Simons anti-de Sitter (AdS) gravity in higher dimensions using first order formalism. We first find asymptotic symmetries in the AdS sector showing that they consist of local translations, local Lorentz rotations, dilatations and non-Abelian gauge transformations. Then, we compute 1-point functions of energy-momentum and spin currents in a dual conformal field theory and write Ward identities. We find that the holographic theory possesses Weyl anomaly and also breaks non-Abelian gauge symmetry at the quantum level.

  16. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ahn, Gail-Joon

    The project seeks an innovative framework to enable users to access and selectively share resources in distributed environments, enhancing the scalability of information sharing. We have investigated secure sharing & assurance approaches for ad-hoc collaboration, focused on Grids, Clouds, and ad-hoc network environments.

  17. How redesigning AD clinical trials might increase study partners’ willingness to participate

    PubMed Central

    Karlawish, Jason; Cary, Mark S.; Rubright, Jonathan; TenHave, Tom

    2008-01-01

    Background: Timely recruiting and retaining participants into Alzheimer disease (AD) clinical trials is a challenge. We used conjoint analysis to identify how alterations in attributes of clinical trial design improve willingness to participate: risk, home visits, car service, or increased chance of receiving intervention. Method: A total of 108 study partners of patients with very mild to severe stage AD rated willingness to allow their relative to participate in eight clinical trials that varied combinations of the four attributes. Results: The highest utility was for home visits (0.89) which essentially compensated for the disutility of high risk (−0.85). The combination of home visits and car service was redundant, with almost no increase in utility over home visits alone. Seventeen percent were willing to participate in a trial with no amenities; the addition of home visits increased predicted willingness to participate to 27%; low risk, home visits, and higher chance of active treatment increased predicted willingness to 60%. The value of reducing the hassles of travel correlated well with measures of AD severity (activities of daily living r = 0.41, p < 0.001; basic activities of daily living r = 0.38, p < 0.001; Neuropsychiatric Inventory severity p = 0.24, p = 0.01; Neuropsychiatric Inventory distress r = 0.23, p < 0.02). No association was found between degree of study partner burden and willingness to tolerate risk of an intervention. Conclusion: Clinical trials that reduce travel inconvenience may offset the disincentive of study features such as the risk of intervention and may also increase willingness to participate. Redesigning trials may also help recruit patients with more severe Alzheimer disease. Shorter recruitment periods and increased retention rates may offset costs of these changes. GLOSSARY AD = Alzheimer disease; BLUP = best linear unbiased prediction; RAQ = Research Attitude Questionnaire. PMID:19047560

  18. Caregivers' male gender is associated with poor nutrient intake in AD families (NuAD-trial).

    PubMed

    Puranen, T M; Pietila, S E; Pitkala, K H; Kautiainen, H; Raivio, M; Eloniemi-Sulkava, U; Jyvakorpi, S K; Suominen, M

    2014-07-01

    Alzheimer patients (AD) are known to be at risk for malnutrition and their older spouses may also have nutritional problems. The aim of our study was to clarify the association of caregivers' sex on the nutrient intake of AD couples. Our study uses the baseline data of a randomized nutritional trial exploring the effectiveness of nutrition intervention among home-dwelling AD patients. The central AD register in Finland was used to recruit AD patients living with a spousal caregiver, 99 couples participated in our study. Nutritional status was assessed using the Mini-Nutritional Assessment (MNA). Nutrient intakes for both AD patients and their spouses were calculated from 3-day food diaries. The mean age of caregivers and AD spouses was 75.2 (SD 7.0) and 77.4 years (SD 5.6), respectively. According to the MNA, 40% of male and 52% of female AD spouses were at risk for malnutrition. Among male caregivers, the mean energy and protein intakes were 1605 kcal (SD 458) and 0.93 g/body kg (SD 0.30), whereas the respective figures for their female AD spouses were 1313 kcal (SD 340) and 0.86 g/body kg (SD 0.32), respectively. Among female caregivers, the mean energy and protein intakes were 1536 kcal (SD 402) and 1.00 g/body kg (SD 0.30), whereas the respective figures for their male AD spouses were 1897 kcal (SD 416) and 1.04 g/body kg (SD 0.30). The interaction between male caregiver sex and lower energy (p<0.001) and lower protein intake (p=0.0048) (adjusted for age and MMSE) was significant. Similar differences between caregiver sexes were observed with the intake of various nutrients. A gender difference exists in the ability to cope with caregiver responsibilities related to nutrition. A need exists for tailored nutritional guidance among older individuals and especially among male caregivers.

  19. Next-Generation A/D Sampler ADS3000+ for VLBI2010

    NASA Technical Reports Server (NTRS)

    Takefuji, Kazuhiro; Takeuchi, Hiroshi; Tsutsumi, Masanori; Koyama, Yasuhiro

    2010-01-01

    A high-speed A/D sampler, called ADS3000+, has been developed in 2008, which can sample one analog signal up to 4 Gbps to versatile Linux PC. After A/D conversion, the ADS3000+ can perform digital signal processing such as real-time DBBC (Digital Base Band Conversion) and FIR filtering such as simple CW RFI filtering using the installed FPGAs. A 4 Gsps fringe test with the ADS3000+ has been successfully performed. The ADS3000+ will not exclusively be used for VLBI but will also be employed in other applications.

  20. 78 FR 10564 - Proposed Modification of Class B Airspace; Minneapolis, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-14

    ... about the proposed design. The Ad Hoc Committee was chaired by the Minnesota Soaring Club representative... Minnesota Soaring Club and Stanton Sport Aviation operations. The Ad Hoc Committee's report provided to the... indicate the proposed modifications would impact the Minnesota Soaring Club and Stanton Sport Aviation...

  1. In vitro binding of anthrax protective antigen on bacteriophage T4 capsid surface through Hoc-capsid interactions: A strategy for efficient display of large full-length proteins

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shivachandra, Sathish B.; Rao, Mangala; Janosi, Laszlo

    2006-02-05

    An in vitro binding system is described to display large full-length proteins on bacteriophage T4 capsid surface at high density. The phage T4 icosahedral capsid features 155 copies of a nonessential highly antigenic outer capsid protein, Hoc, at the center of each major capsid protein hexon. Gene fusions were engineered to express the 83-kDa protective antigen (PA) from Bacillus anthracis fused to the N-terminus of Hoc and the 130-kDa PA-Hoc protein was expressed in Escherichia coli and purified. The purified PA-Hoc was assembled in vitro on hoc {sup -} phage particles. Binding was specific, stable, and of high affinity. Thismore » defined in vitro system allowed manipulation of the copy number of displayed PA and imposed no significant limitation on the size of the displayed antigen. In contrast to in vivo display systems, the in vitro approach allows all the capsid binding sites to be occupied by the 130-kDa PA-Hoc fusion protein. The PA-T4 particles were immunogenic in mice in the absence of an adjuvant, eliciting strong PA-specific antibodies and anthrax lethal toxin neutralizing antibodies. The in vitro display on phage T4 offers a novel platform for potential construction of customized vaccines against anthrax and other infectious diseases.« less

  2. Dynamic Hierarchical Sleep Scheduling for Wireless Ad-Hoc Sensor Networks

    PubMed Central

    Wen, Chih-Yu; Chen, Ying-Chih

    2009-01-01

    This paper presents two scheduling management schemes for wireless sensor networks, which manage the sensors by utilizing the hierarchical network structure and allocate network resources efficiently. A local criterion is used to simultaneously establish the sensing coverage and connectivity such that dynamic cluster-based sleep scheduling can be achieved. The proposed schemes are simulated and analyzed to abstract the network behaviors in a number of settings. The experimental results show that the proposed algorithms provide efficient network power control and can achieve high scalability in wireless sensor networks. PMID:22412343

  3. Dynamic hierarchical sleep scheduling for wireless ad-hoc sensor networks.

    PubMed

    Wen, Chih-Yu; Chen, Ying-Chih

    2009-01-01

    This paper presents two scheduling management schemes for wireless sensor networks, which manage the sensors by utilizing the hierarchical network structure and allocate network resources efficiently. A local criterion is used to simultaneously establish the sensing coverage and connectivity such that dynamic cluster-based sleep scheduling can be achieved. The proposed schemes are simulated and analyzed to abstract the network behaviors in a number of settings. The experimental results show that the proposed algorithms provide efficient network power control and can achieve high scalability in wireless sensor networks.

  4. Reinforcement learning for routing in cognitive radio ad hoc networks.

    PubMed

    Al-Rawi, Hasan A A; Yau, Kok-Lim Alvin; Mohamad, Hafizal; Ramli, Nordin; Hashim, Wahidah

    2014-01-01

    Cognitive radio (CR) enables unlicensed users (or secondary users, SUs) to sense for and exploit underutilized licensed spectrum owned by the licensed users (or primary users, PUs). Reinforcement learning (RL) is an artificial intelligence approach that enables a node to observe, learn, and make appropriate decisions on action selection in order to maximize network performance. Routing enables a source node to search for a least-cost route to its destination node. While there have been increasing efforts to enhance the traditional RL approach for routing in wireless networks, this research area remains largely unexplored in the domain of routing in CR networks. This paper applies RL in routing and investigates the effects of various features of RL (i.e., reward function, exploitation, and exploration, as well as learning rate) through simulation. New approaches and recommendations are proposed to enhance the features in order to improve the network performance brought about by RL to routing. Simulation results show that the RL parameters of the reward function, exploitation, and exploration, as well as learning rate, must be well regulated, and the new approaches proposed in this paper improves SUs' network performance without significantly jeopardizing PUs' network performance, specifically SUs' interference to PUs.

  5. Network Management System for Tactical Mobile Ad Hoc Network Segments

    DTIC Science & Technology

    2011-09-01

    Protocol UFO UHF Follow-On UHF Ultra High Frequency USB Universal Serial Bus VHF Very High Frequency VIRT Valuable Information at the Right Time...military satellite system known as the UHF Follow-on system ( UFO ) only provides capacity for 600 concurrent users. DoD users also have commercial

  6. A Black Hole Attack Model for Reactive Ad-Hoc Protocols

    DTIC Science & Technology

    2012-03-01

    Technology Conference. IEEE, 2003. pp. 2286-2290. [BhS09] N. Bhalaji, and A. Shanmugam. "Association Between Nodes to Combat Blackhole Attack in DSR...2012. 102 [PSA09] A. Prathapani, L. Santhanam, and P. Agrawal. "Intelligent Honeypot Agent for Blackhole Attack Detection in Wireless Mesh

  7. PinaColada: peptide-inhibitor ant colony ad-hoc design algorithm.

    PubMed

    Zaidman, Daniel; Wolfson, Haim J

    2016-08-01

    Design of protein-protein interaction (PPI) inhibitors is a major challenge in Structural Bioinformatics. Peptides, especially short ones (5-15 amino acid long), are natural candidates for inhibition of protein-protein complexes due to several attractive features such as high structural compatibility with the protein binding site (mimicking the surface of one of the proteins), small size and the ability to form strong hotspot binding connections with the protein surface. Efficient rational peptide design is still a major challenge in computer aided drug design, due to the huge space of possible sequences, which is exponential in the length of the peptide, and the high flexibility of peptide conformations. In this article we present PinaColada, a novel computational method for the design of peptide inhibitors for protein-protein interactions. We employ a version of the ant colony optimization heuristic, which is used to explore the exponential space ([Formula: see text]) of length n peptide sequences, in combination with our fast robotics motivated PepCrawler algorithm, which explores the conformational space for each candidate sequence. PinaColada is being run in parallel, on a DELL PowerEdge 2.8 GHZ computer with 20 cores and 256 GB memory, and takes up to 24 h to design a peptide of 5-15 amino acids length. An online server available at: http://bioinfo3d.cs.tau.ac.il/PinaColada/. danielza@post.tau.ac.il; wolfson@tau.ac.il. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. Condensed Proceedings of the Ad Hoc Committee on Environmental Behavior

    ERIC Educational Resources Information Center

    Cancro, Robert

    1972-01-01

    Fourteen leading behavioral scientists explore the relationship between environment and health with a focus on the following question: As we look at health care as people receive it in their communities and the realities of America today, what can we do to improve it?'' Philosophical, scientific issues discussed in round table fashion. (LK)

  9. Self-Configuration and Localization in Ad Hoc Wireless Sensor Networks

    DTIC Science & Technology

    2010-08-31

    Goddard I. SUMMARY OF CONTRIBUTIONS We explored the error mechanisms of iterative decoding of low-density parity-check ( LDPC ) codes . This work has resulted...important problems in the area of channel coding , as their unpredictable behavior has impeded the deployment of LDPC codes in many real-world applications. We...tree-based decoders of LDPC codes , including the extrinsic tree decoder, and an investigation into their performance and bounding capabilities [5], [6

  10. Reinforcement Learning for Routing in Cognitive Radio Ad Hoc Networks

    PubMed Central

    Al-Rawi, Hasan A. A.; Mohamad, Hafizal; Hashim, Wahidah

    2014-01-01

    Cognitive radio (CR) enables unlicensed users (or secondary users, SUs) to sense for and exploit underutilized licensed spectrum owned by the licensed users (or primary users, PUs). Reinforcement learning (RL) is an artificial intelligence approach that enables a node to observe, learn, and make appropriate decisions on action selection in order to maximize network performance. Routing enables a source node to search for a least-cost route to its destination node. While there have been increasing efforts to enhance the traditional RL approach for routing in wireless networks, this research area remains largely unexplored in the domain of routing in CR networks. This paper applies RL in routing and investigates the effects of various features of RL (i.e., reward function, exploitation, and exploration, as well as learning rate) through simulation. New approaches and recommendations are proposed to enhance the features in order to improve the network performance brought about by RL to routing. Simulation results show that the RL parameters of the reward function, exploitation, and exploration, as well as learning rate, must be well regulated, and the new approaches proposed in this paper improves SUs' network performance without significantly jeopardizing PUs' network performance, specifically SUs' interference to PUs. PMID:25140350

  11. A Discovery Process for Initializing Ad Hoc Underwater Acoustic Networks

    DTIC Science & Technology

    2008-12-01

    the ping utility packet is set to global address 0, its function becomes a broadcast ping and it elicits echoes from all neighboring nodes within...destination. At the Seaweb server, a global neighbor table and a global routing table are maintained to support network configurability. 2. Cellular...aggregates the received peer discovery data in a global neighbor table and ultimately decides how routing to each branch node should be configured

  12. Applying Ad Hoc Institutional Research Findings to College Strategic Planning

    ERIC Educational Resources Information Center

    Clagett, Craig A.

    2004-01-01

    Environmental scanning, enrollment forecasting, budget analyses, and institutional effectiveness assessment are examples of the explicit contributions institutional research offices make to campus strategic planning.

  13. GBSFP: General Bluetooth Scatternet Formation Protocol for Ad Hoc Networking

    NASA Astrophysics Data System (ADS)

    Lim, Chaegwon; Huh, Myung-Sun; Choi, Chong-Ho; Jeong, Gu-Min

    Recently, bluetooth technology has become widely prevalent so that many laptops and mobile phones are equipped with bluetooth capability. In order to meet the increasing demand to interconnect these devices a new scatternet formation protocol named GBSFP (General Bluetooth Scatternet Formation Protocol) is proposed in this paper. GBSFP is the result of efforts to overcome the two major limitations of the legacy scatternet formation protocols as regards their real implementation, that all of the nodes should be within the Bluetooth communication range or that they should be time synchronized. In GBSFP, a node goes through three phases; 1) the Init phase to establish a bluetooth link to as many of its neighbors as possible, 2) the Ready phase to determine the role of each node, i.e., master or slave, and remove any unnecessary bluetooth links, and 3) the Complete phase to finalize the formation of the scatternet and begin data transmission. The simulation results show that GBSFP provides higher connectivity in many scenarios compared with BTCP and BlueStars.

  14. Army Science Board Ad Hoc Subgroup Report, Manning Army Systems

    DTIC Science & Technology

    1982-09-01

    systems that are being intro- duced, there was a worry that the full scope of the problem was not yet understood and that some sort of disaster might...be impending. The letter requesting the formation of an ASB panel and the Terms of Reference for the panel are at Appen- dix A . The membership of...the panel is shown at Appendix B. The panel met for a total of 10 days between 31 August 1981 and 7 May 1982. As a first step, in order to form our

  15. Canadian Mathematics Education Study Group = Groupe Canadien d'Etude en Didactique des Mathematiques. Proceedings of the Annual Meeting (25th, Edmonton, Alberta, Canada, May 25-29, 2001).

    ERIC Educational Resources Information Center

    Simmt, Elaine, Ed.; Davis, Brent, Ed.

    2001-01-01

    This document contains the proceedings of the 2001 annual meeting of the Canadian Mathematics Education Study Group (CMESG) held at the University of Alberta, May 25-39, 2000. The proceedings consist of two plenary lectures, four working groups, five topic sessions, new Ph.D. reports, an AD Hoc Session, and panel discussions. Papers include: (1)…

  16. Thermodynamic Volume in AdS/CFT

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Kiu; Ahn, Byoungjoon

    2018-01-01

    In this note, we study on extended thermodynamics of AdS black holes by varying cosmological constant. We found and discussed pressure and volume of both bulk and boundary physics through AdS/CFT correspondence. In particular, we derive the relation between thermodynamic volume and a chemical potential for M2 brane dual to four dimensional AdS space. In addition, we show that thermodynamic volume of hyperbolic black hole is related to `entanglement pressure' coming from a generalized first law of entanglement entropy.

  17. Temporal patterns of scientific information-seeking on Google and Wikipedia.

    PubMed

    Segev, Elad; Sharon, Aviv J

    2017-11-01

    In response to the news coverage of scientific events and to science education, people increasingly go online to get more information. This study investigates how patterns of science and technology information-seeking on Google and Wikipedia change over time, in ways that differ between "ad hoc" terms that correspond to news coverage and "cyclic" terms that correspond to the academic period. Findings show that the science and technology activity in Google and Wikipedia was significantly associated with ad hoc and cyclic patterns. While the peak activity in Google and Wikipedia largely overlapped for ad hoc terms, it mismatched for cyclic terms. The findings indicate the importance of external cues such as news media and education, and also of the online engagement process, and particularly the crucial but different role played by Google and Wikipedia in gaining science and technology knowledge. Educators and policy makers could benefit from taking into account those different patterns.

  18. Glutamine and antioxidants in the critically ill patient: a post hoc analysis of a large-scale randomized trial.

    PubMed

    Heyland, Daren K; Elke, Gunnar; Cook, Deborah; Berger, Mette M; Wischmeyer, Paul E; Albert, Martin; Muscedere, John; Jones, Gwynne; Day, Andrew G

    2015-05-01

    The recent large randomized controlled trial of glutamine and antioxidant supplementation suggested that high-dose glutamine is associated with increased mortality in critically ill patients with multiorgan failure. The objectives of the present analyses were to reevaluate the effect of supplementation after controlling for baseline covariates and to identify potentially important subgroup effects. This study was a post hoc analysis of a prospective factorial 2 × 2 randomized trial conducted in 40 intensive care units in North America and Europe. In total, 1223 mechanically ventilated adult patients with multiorgan failure were randomized to receive glutamine, antioxidants, both glutamine and antioxidants, or placebo administered separate from artificial nutrition. We compared each of the 3 active treatment arms (glutamine alone, antioxidants alone, and glutamine + antioxidants) with placebo on 28-day mortality. Post hoc, treatment effects were examined within subgroups defined by baseline patient characteristics. Logistic regression was used to estimate treatment effects within subgroups after adjustment for baseline covariates and to identify treatment-by-subgroup interactions (effect modification). The 28-day mortality rates in the placebo, glutamine, antioxidant, and combination arms were 25%, 32%, 29%, and 33%, respectively. After adjusting for prespecified baseline covariates, the adjusted odds ratio of 28-day mortality vs placebo was 1.5 (95% confidence interval, 1.0-2.1, P = .05), 1.2 (0.8-1.8, P = .40), and 1.4 (0.9-2.0, P = .09) for glutamine, antioxidant, and glutamine plus antioxidant arms, respectively. In the post hoc subgroup analysis, both glutamine and antioxidants appeared most harmful in patients with baseline renal dysfunction. No subgroups suggested reduced mortality with supplements. After adjustment for baseline covariates, early provision of high-dose glutamine administered separately from artificial nutrition was not beneficial and may be

  19. Adiabatic pumping solutions in global AdS

    NASA Astrophysics Data System (ADS)

    Carracedo, Pablo; Mas, Javier; Musso, Daniele; Serantes, Alexandre

    2017-05-01

    We construct a family of very simple stationary solutions to gravity coupled to a massless scalar field in global AdS. They involve a constantly rising source for the scalar field at the boundary and thereby we name them pumping solutions. We construct them numerically in D = 4. They are regular and, generically, have negative mass. We perform a study of linear and nonlinear stability and find both stable and unstable branches. In the latter case, solutions belonging to different sub-branches can either decay to black holes or to limiting cycles. This observation motivates the search for non-stationary exactly timeperiodic solutions which we actually construct. We clarify the role of pumping solutions in the context of quasistatic adiabatic quenches. In D = 3 the pumping solutions can be related to other previously known solutions, like magnetic or translationally-breaking backgrounds. From this we derive an analytic expression.

  20. Post-Hoc Study: Intravenous Hydration Treatment in Chinese Patients with High Risk of Contrast-Induced Nephropathy Following Percutaneous Coronary Intervention

    PubMed Central

    Bei, Weijie; Li, Hualong; Lin, Kaiyang; Wang, Kun; Chen, Shiqun; Guo, Xiaosheng; Liu, Yong; Tan, Ning; Chen, Jiyan; Yang, Xiangtai; Su, Xi; Du, Zhimin; Zeng, Qiutang; Fang, Zhenfei; Wang, Yan; Jiang, Hong; Xiong, Longgen; Hou, Yuqing; Yuan, Yong; Li, Tianfa; Hong, Lang; Wu, Yanqing; Liu, Yin; Lin, Wenhua; Jiang, Tiemin; Fu, Junhua; An, Yi; Yu, Bo; Tian, Ye; Zheng, Yang; Liu, Bin; Yang, Ping; Jiang, Xianyan; Wang, Hao; Qu, Peng; Cui, Lianqun; Li, Xueqi; Qi, Xiaoyong; Ma, Zengcai; Li, Jifu; Zhang, Lili; Liu, Shengquan; Pang, Wenyue; Li, Yibo; Yang, Manguang; Ji, Zheng; Zhao, Pitian; Li, Lu; Ge, Junbo; Jin, Huigen; Pan, Weimin; Song, Yaoming; Li, Jianmei; Xiao, Jianming; Liu, Hanxiong; Tao, Jianhong; Wu, Zhongdong; Tuo, Buxiong; Li, Wei; Xu, Yixian; Zhang, Zhaoqi; Chen, Yundai; Wang, Lefeng; Zhang, Jinying; Wang, Fengling; Jia, Yongping; Wang, Bin; Tang, Fakuan; Tang, Qiang; Wang, Wei; Sun, Yuemin; Su, Weiqing

    2017-01-01

    Contrast-induced nephropathy (CIN) develops after the injection of iodinated contrast media. This is a post hoc analysis of the data obtained from the TRUST study, which was a prospective, multicentre, observational study conducted to evaluate the safety and tolerability of the contrast medium iopromide in patients undergoing cardiac catheterization from August 2010 to September 2011 in China, conducted to explore the current status, trends and risk predictors of hydration treatment. The status of hydration to prevent CIN in each patient was recorded. Of the total 17,139 patients from the TRUST study (mean age, 60.33 ± 10.38 years), the overall hydration usage was 46.1% in patients undergoing percutaneous coronary intervention (PCI) and 77.4%, 51.7%, and 48.5% in patients with pre-existing renal disease, diabetes mellitus, and hypertension, respectively. The proportion of hydration use increased from 36.5% to 55.5% from August 2010 to September 2011, which was independently associated with risk predictors like older age, pre-existing renal disease, hypertension, diabetes mellitus, prior myocardial infarction, ST segment elevation MI, high contrast dose, multi-vessel disease and reduced LVEF (<45%). Overall, the usage of intravenous hydration treatment for patients with a high risk of CIN following PCI was high in China. PMID:28337989

  1. Vibrational Frequencies and Spectroscopic Constants for 1(sup 3)A' HNC and 1(sup 3)A' HOC+ from High-Accuracy Quartic Force Fields

    NASA Technical Reports Server (NTRS)

    Fortenberry, Ryan C.; Crawford, T. Daniel; Lee, Timothy J.

    2014-01-01

    The spectroscopic constants and vibrational frequencies for the 1(sup 3)A' states of HNC, DNC, HOC+, and DOC+ are computed and discussed in this work. The reliable CcCR quartic force field based on high-level coupled cluster ab initio quantum chemical computations is exclusively utilized to provide the anharmonic potential. Then, second order vibrational perturbation theory and vibrational configuration interaction methods are employed to treat the nuclear Schroedinger equation. Second-order perturbation theory is also employed to provide spectroscopic data for all molecules examined. The relationship between these molecules and the corresponding 1(sup 3)A' HCN and HCO+ isomers is further developed here. These data are applicable to laboratory studies involving formation of HNC and HOC+ as well as astronomical observations of chemically active astrophysical environments.

  2. Gemini: Extending Information Management for Real Time Tactical Environments

    DTIC Science & Technology

    2008-03-01

    Mobile,  AdHoc  Networks.......................................................................................................49  8.4  Wired...networks, such as  wireless  adhoc  networks. This paper looked into the operating environments expected to be available to  Unmanned Aircraft Systems...decentralized,  adhoc   networks. The total peering capability of these networks may be very large. And, each network or access  point may carry restrictions; for

  3. Moving beyond Univariate Post-Hoc Testing in Exercise Science: A Primer on Descriptive Discriminate Analysis

    ERIC Educational Resources Information Center

    Barton, Mitch; Yeatts, Paul E.; Henson, Robin K.; Martin, Scott B.

    2016-01-01

    There has been a recent call to improve data reporting in kinesiology journals, including the appropriate use of univariate and multivariate analysis techniques. For example, a multivariate analysis of variance (MANOVA) with univariate post hocs and a Bonferroni correction is frequently used to investigate group differences on multiple dependent…

  4. Diffusion and chaos from near AdS 2 horizons

    DOE PAGES

    Blake, Mike; Donos, Aristomenis

    2017-02-03

    We calculate the thermal diffusivity D =more » $$\\kappa/c_\\rho$$ and butterfy velocity $$\\upsilon_\\beta$$ in holographic models that flow to $$AdS_2$$ x $R^d$ fixed points in the infra-red. We show that both these quantities are governed by the same irrelevant deformation of $$AdS_2$$ and hence establish a simple relationship between them. When this deformation corresponds to a universal dilaton mode of dimension $$\\Delta$$ = 2 then this relationship is always given by D = $$\\upsilon_B^2$$/(2$$\\pi$$T).« less

  5. 7 CFR 3400.14 - Proposal review.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... RESEARCH GRANTS PROGRAM Scientific Peer Review of Research Grant Applications § 3400.14 Proposal review. (a... review will be made for responsiveness to the request for proposals (e.g., relationship of application to... peer review group, and ad hoc reviewers, as required. Written comments will be solicited from ad hoc...

  6. Geometry and supersymmetry of heterotic warped flux AdS backgrounds

    NASA Astrophysics Data System (ADS)

    Beck, S.; Gutowski, J.; Papadopoulos, G.

    2015-07-01

    We classify the geometries of the most general warped, flux AdS backgrounds of heterotic supergravity up to two loop order in sigma model perturbation theory. We show under some mild assumptions that there are no AdS n backgrounds with n ≠ 3. Moreover the warp factor of AdS3 backgrounds is constant, the geometry is a product AdS 3 × M 7 and such solutions preserve, 2, 4, 6 and 8 supersymmetries. The geometry of M 7 has been specified in all cases. For 2 supersymmetries, it has been found that M 7 admits a suitably restricted G 2 structure. For 4 supersymmetries, M 7 has an SU(3) structure and can be described locally as a circle fibration over a 6-dimensional KT manifold. For 6 and 8 supersymmetries, M 7 has an SU(2) structure and can be described locally as a S 3 fibration over a 4-dimensional manifold which either has an anti-self dual Weyl tensor or a hyper-Kähler structure, respectively. We also demonstrate a new Lichnerowicz type theorem in the presence of α' corrections.

  7. [Value-Added--Adding Economic Value in the Food Industry].

    ERIC Educational Resources Information Center

    Welch, Mary A., Ed.

    1989-01-01

    This booklet focuses on the economic concept of "value added" to goods and services. A student activity worksheet illustrates how the steps involved in processing food are examples of the concept of value added. The booklet further links food processing to the idea of value added to the Gross National Product (GNP). Discussion questions,…

  8. PET textural features stability and pattern discrimination power for radiomics analysis: An "ad-hoc" phantoms study.

    PubMed

    Presotto, L; Bettinardi, V; De Bernardi, E; Belli, M L; Cattaneo, G M; Broggi, S; Fiorino, C

    2018-06-01

    The analysis of PET images by textural features, also known as radiomics, shows promising results in tumor characterization. However, radiomic metrics (RMs) analysis is currently not standardized and the impact of the whole processing chain still needs deep investigation. We characterized the impact on RM values of: i) two discretization methods, ii) acquisition statistics, and iii) reconstruction algorithm. The influence of tumor volume and standardized-uptake-value (SUV) on RM was also investigated. The Chang-Gung-Image-Texture-Analysis (CGITA) software was used to calculate 39 RMs using phantom data. Thirty noise realizations were acquired to measure statistical effect size indicators for each RM. The parameter η 2 (fraction of variance explained by the nuisance factor) was used to assess the effect of categorical variables, considering η 2  < 20% and 20% < η 2  < 40% as representative of a "negligible" and a "small" dependence respectively. The Cohen's d was used as discriminatory power to quantify the separation of two distributions. We found the discretization method based on fixed-bin-number (FBN) to outperform the one based on fixed-bin-size in units of SUV (FBS), as the latter shows a higher SUV dependence, with 30 RMs showing η 2  > 20%. FBN was also less influenced by the acquisition and reconstruction setup:with FBN 37 RMs had η 2  < 40%, only 20 with FBS. Most RMs showed a good discriminatory power among heterogeneous PET signals (for FBN: 29 out of 39 RMs with d > 3). For RMs analysis, FBN should be preferred. A group of 21 RMs was suggested for PET radiomics analysis. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  9. Spin Filtering Studies at COSY and AD

    NASA Astrophysics Data System (ADS)

    Nass, Alexander

    2009-08-01

    The high physics potential of experiments with stored high-energy polarized antiprotons led to the proposal of PAX (Polarized Antiproton eXperiment) [1] for the High Energy Storage Ring (HESR) of the FAIR at GSI (Darmstadt/Germany). It is proposed to polarize a stored antiproton beam by means of spin filtering with a polarized H (D) gas target. The feasibility of spin filtering has been demonstrated in the FILTEX experiment. The current interpretation foresees a self-cancellation of the electron contribution to the filtering process and only the hadronic contribution is effective. Several experimental studies with protons (at COSY/Jülich) as well as antiprotons (at AD/CERN) will be carried out to test the principle and measure p¯p⃗ and p¯d⃗ cross sections. A polarized internal gas target (PIT) with surrounding Silicon detectors immersed into a low-β section has to be set up.

  10. Monitoring and tracing of critical software systems: State of the work and project definition

    DTIC Science & Technology

    2008-12-01

    analysis, troubleshooting and debugging. Some of these subsystems already come with ad hoc tracers for events like wireless connections or SCSI disk... SQLite ). Additional synthetic events (e.g. states) are added to the database. The database thus consists in contexts (process, CPU, state), event...capability on a [operating] system-by-system basis. Additionally, the mechanics of querying the data in an ad - hoc manner outside the boundaries of the

  11. The Time-Course of Sentence Meaning Composition. N400 Effects of the Interaction between Context-Induced and Lexically Stored Affordances

    PubMed Central

    Cosentino, Erica; Baggio, Giosuè; Kontinen, Jarmo; Werning, Markus

    2017-01-01

    Contemporary semantic theories can be classified along two dimensions: (i) the way and time-course in which contextual factors influence sentence truth-conditions; and (ii) whether and to what extent comprehension involves sensory, motor and emotional processes. In order to explore this theoretical space, our ERP study investigates the time-course of the interaction between the lexically specified telic component of a noun (the function of the object to which the noun refers to, e.g., a funnel is generally used to pour liquids into containers) and an ad-hoc affordance contextually induced by the situation described in the discourse. We found that, if preceded by a neutral discourse context, a verb incongruent with the noun's telic component as in “She uses the funnel to hang her coat” elicited an enhanced N400 compared to a congruent verb as in “She uses the funnel to pour water into a container.” However, if the situation introduced in the preceding discourse induced a new function for the object as an ad-hoc affordance (e.g., the funnel is glued to the wall and the agent wants to hang the coat), we observed a crossing-over regarding the direction of the N400 effect: comparing the ad-hoc affordance-inducing context with the neutral context, the N400 for the incongruent verb was significantly reduced, whereas the N400 for the congruent verb was significantly enhanced. We explain these results as a consequence of the incorporation of the contextually triggered ad-hoc affordance into the meaning of the noun. Combining these results with an analysis of semantic similarity values between test sentences and contexts, we argue that one possibility is that the incorporation of an ad-hoc affordance may be explained on the basis of the mental simulation of concurrent motor information. PMID:28603506

  12. The Time-Course of Sentence Meaning Composition. N400 Effects of the Interaction between Context-Induced and Lexically Stored Affordances.

    PubMed

    Cosentino, Erica; Baggio, Giosuè; Kontinen, Jarmo; Werning, Markus

    2017-01-01

    Contemporary semantic theories can be classified along two dimensions: (i) the way and time-course in which contextual factors influence sentence truth-conditions; and (ii) whether and to what extent comprehension involves sensory, motor and emotional processes. In order to explore this theoretical space, our ERP study investigates the time-course of the interaction between the lexically specified telic component of a noun (the function of the object to which the noun refers to, e.g., a funnel is generally used to pour liquids into containers) and an ad-hoc affordance contextually induced by the situation described in the discourse. We found that, if preceded by a neutral discourse context, a verb incongruent with the noun's telic component as in "She uses the funnel to hang her coat" elicited an enhanced N400 compared to a congruent verb as in "She uses the funnel to pour water into a container." However, if the situation introduced in the preceding discourse induced a new function for the object as an ad-hoc affordance (e.g., the funnel is glued to the wall and the agent wants to hang the coat), we observed a crossing-over regarding the direction of the N400 effect: comparing the ad-hoc affordance-inducing context with the neutral context, the N400 for the incongruent verb was significantly reduced, whereas the N400 for the congruent verb was significantly enhanced. We explain these results as a consequence of the incorporation of the contextually triggered ad-hoc affordance into the meaning of the noun. Combining these results with an analysis of semantic similarity values between test sentences and contexts, we argue that one possibility is that the incorporation of an ad-hoc affordance may be explained on the basis of the mental simulation of concurrent motor information.

  13. Korea Institute for Advanced Study Value-Added Galaxy Catalog

    NASA Astrophysics Data System (ADS)

    Choi, Yun-Young; Han, Du-Hwan; Kim, Sungsoo S.

    2010-12-01

    We present the Korea Institute for Advanced Study Value-Added Galaxy Catalog (KIAS VAGC),a catalog of galaxies based on the Large Scale Structure (LSS) sample of New York University Value-Added Galaxy Catalog (NYU VAGC) Data Release 7. Our catalog supplements redshifts of 10,497 galaxies with 10 < r_{P} ≤ 17.6 (1455 with 10 < r_{P} ≤ 14.5) to the NYU VAGC LSS sample. Redshifts from various existing catalogs such as the Updated Zwicky Catalog, the IRAS Point Source Catalog Redshift Survey, the Third Reference Catalogue of Bright Galaxies, and the Two Degree Field Galaxy Redshift Survey have been put into the NYU VAGC photometric catalog. Our supplementation significantly improves spectroscopic completeness: the area covered by the spectroscopic sample with completeness higher than 95% increases from 2.119 to 1.737 sr.Our catalog also provides morphological types of all galaxies that are determined by the automated morphology classification scheme of Park & Choi (2005), and related parameters, together with fundamental photometry parameters supplied by the NYU VAGC. Our catalog contains matches to objects in the Max Planck for Astronomy (MPA) & Johns Hopkins University (JHU) spectrum measurements (Data Release 7). This new catalog, the KIAS VAGC, is complementary to the NYU VAGC and MPA-JHU catalog.

  14. Benefits of Using Planned Comparisons Rather Than Post Hoc Tests: A Brief Review with Examples.

    ERIC Educational Resources Information Center

    DuRapau, Theresa M.

    The rationale behind analysis of variance (including analysis of covariance and multiple analyses of variance and covariance) methods is reviewed, and unplanned and planned methods of evaluating differences between means are briefly described. Two advantages of using planned or a priori tests over unplanned or post hoc tests are presented. In…

  15. Fine Grained Chaos in AdS2 Gravity

    NASA Astrophysics Data System (ADS)

    Haehl, Felix M.; Rozali, Moshe

    2018-03-01

    Quantum chaos can be characterized by an exponential growth of the thermal out-of-time-order four-point function up to a scrambling time u^*. We discuss generalizations of this statement for certain higher-point correlation functions. For concreteness, we study the Schwarzian theory of a one-dimensional time reparametrization mode, which describes two-dimensional anti-de Sitter space (AdS2 ) gravity and the low-energy dynamics of the Sachdev-Ye-Kitaev model. We identify a particular set of 2 k -point functions, characterized as being both "maximally braided" and "k -out of time order," which exhibit exponential growth until progressively longer time scales u^*(k)˜(k -1 )u^*. We suggest an interpretation as scrambling of increasingly fine grained measures of quantum information, which correspondingly take progressively longer time to reach their thermal values.

  16. Fine Grained Chaos in AdS_{2} Gravity.

    PubMed

    Haehl, Felix M; Rozali, Moshe

    2018-03-23

    Quantum chaos can be characterized by an exponential growth of the thermal out-of-time-order four-point function up to a scrambling time u[over ^]_{*}. We discuss generalizations of this statement for certain higher-point correlation functions. For concreteness, we study the Schwarzian theory of a one-dimensional time reparametrization mode, which describes two-dimensional anti-de Sitter space (AdS_{2}) gravity and the low-energy dynamics of the Sachdev-Ye-Kitaev model. We identify a particular set of 2k-point functions, characterized as being both "maximally braided" and "k-out of time order," which exhibit exponential growth until progressively longer time scales u[over ^]_{*}^{(k)}∼(k-1)u[over ^]_{*}. We suggest an interpretation as scrambling of increasingly fine grained measures of quantum information, which correspondingly take progressively longer time to reach their thermal values.

  17. Thermodynamic Geometry of Charged AdS Black Hole Surrounded by Quintessence

    NASA Astrophysics Data System (ADS)

    Wei, Shao-Wen; Man, Qing-Tao; Yu, Hao

    2018-02-01

    In this paper, we study the thermodynamic geometry for the charged AdS black hole surrounded by quintessence. Three different kinds of the geometries are constructed, and the corresponding curvatures are obtained. It is found that there are different divergence behaviors of these curvatures, which is general thought to closely link to the phase transition of the black hole. Supported by the National Natural Science Foundation of China under Grant Nos. 11675064, 11205074, and the Fundamental Research Funds for the Central Universities under Grant No. lzujbky-2016-121

  18. The Description and Indexing of Editorial Cartoons: An Exploratory Study

    ERIC Educational Resources Information Center

    Landbeck, Christopher Ryan

    2013-01-01

    While access to images in general has improved in the last 20 years, due to both advances in electronic storage and dissemination and to improvements in the intellectual provisions of them, access to editorial cartoons lags behind access to other types of images. While there have been piecemeal or ad hoc efforts to organize large cartoon…

  19. Semiclassical Virasoro blocks from AdS 3 gravity

    DOE PAGES

    Hijano, Eliot; Kraus, Per; Perlmutter, Eric; ...

    2015-12-14

    We present a unified framework for the holographic computation of Virasoro conformal blocks at large central charge. In particular, we provide bulk constructions that correctly reproduce all semiclassical Virasoro blocks that are known explicitly from conformal field theory computations. The results revolve around the use of geodesic Witten diagrams, recently introduced in [1], evaluated in locally AdS 3 geometries generated by backreaction of heavy operators. We also provide an alternative computation of the heavy-light semiclassical block — in which two external operators become parametrically heavy — as a certain scattering process involving higher spin gauge fields in AdS 3; thismore » approach highlights the chiral nature of Virasoro blocks. Finally, these techniques may be systematically extended to compute corrections to these blocks and to interpolate amongst the different semiclassical regimes.« less

  20. EXACT S-MATRICES FOR AdS3/CFT2

    NASA Astrophysics Data System (ADS)

    Ahn, Changrim; Bombardelli, Diego

    2013-12-01

    We propose exact S-matrices for the AdS3/CFT2 duality between type IIB strings on AdS3×S3×M4 with M4 = S3×S1 or T4 and the corresponding two-dimensional conformal field theories. We fix the two-particle S-matrices on the basis of the symmetries su(1|1) and su(1|1)×su(1|1). A crucial justification comes from the derivation of the all-loop Bethe ansatz matching exactly the recent conjecture proposed by Babichenko et al. [J. High Energy Phys.1003, 058 (2010), arXiv:0912.1723 [hep-th