Science.gov

Sample records for ad hoc studies

  1. Metadata-driven Ad Hoc Query of Clinical Studies Data

    PubMed Central

    Deshpande, Aniruddha M.; Nadkarni, Prakash M.

    2001-01-01

    The Entity-Attribute-Value (EAV) data representation is widely used in both clinical patient record systems (CPRSs) and clinical study data management systems (CSDMS). Both of these systems are heterogeneous in that many types of data are also represented conventionally, a situation that complicates data display, editing and ad hoc query. Seamless functioning of such systems mandates the presence of developer-defined metadata (data describing the rest of the database) that records, among other things, how individual parameters are represented within the system. We illustrate a web-based ad hoc query tool that relies on the metadata to generate syntactically and semantically correct SQL.

  2. 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.

  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. 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

  5. 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.

  6. 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…

  7. Supporting Dynamic Ad hoc Collaboration Capabilities

    SciTech Connect

    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. 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.

  8. Routing Security in Ad Hoc Wireless Networks

    NASA Astrophysics Data System (ADS)

    Pervaiz, Mohammad O.; Cardei, Mihaela; Wu, Jie

    Wireless networks provide rapid, untethered access to information and computing, eliminating the barriers of distance, time, and location for many applications ranging from collaborative, distributed mobile computing to disaster recovery (such as fire, flood, earthquake), law enforcement (crowd control, search, and rescue), and military communications (command, control, surveillance, and reconnaissance). An ad hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration [11

  9. 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... NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the...

  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... Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the Committee's work....

  11. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  12. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  13. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  14. 14 CFR § 1203.803 - Ad hoc committees.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Ad hoc committees. § 1203.803 Section Â... PROGRAM Delegation of Authority To Make Determinations in Original Classification Matters § 1203.803 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as...

  15. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Ad hoc committees. 1203.903 Section 1203... NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the...

  16. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  17. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Ad hoc committees. 1203.903 Section 1203... NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the...

  18. 14 CFR § 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Ad hoc committees. § 1203.903 Section Â... PROGRAM NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of...

  19. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  20. Ad Hoc Networks: Headline 2000 Communications Analysis

    NASA Astrophysics Data System (ADS)

    Blair, W. D.; Reynolds, A. B.

    2002-06-01

    This report examines unit location data and terrain from Headline 2000 to investigate communications networks within the maneuver units. Within the Enhanced Combat Force timeframe, such units would be supported by a Tactical Data Distribution Sub-system (TDDS). This is envisaged as an ad hoc network changing its topology as units maneuver across the battlespace. The report describes approaches that can be applied to Headline 2000 and other data to characterize the nature of the network topology, both statically and as it changes over time, in order to explore the impact on the TDDS network capacity and hence to hence to assist in elucidating consequent requirements of a candidate TDDS.

  1. Report of the Ad Hoc Committee on Scope and Sequence.

    ERIC Educational Resources Information Center

    Hergesheimer, John; And Others

    1989-01-01

    Describes the establishment of the Ad Hoc Committee on Scope and Sequence by the National Council for the Social Studies (NCSS). Outlines the responsibilities of the Committee, the process used to formulate curriculum criteria and the resultant criteria for social studies education curriculum design. (SLM)

  2. Declarative ad-hoc sensor networking

    NASA Astrophysics Data System (ADS)

    Coffin, Daniel A.; Van Hook, Daniel J.; McGarry, Stephen M.; Kolek, Stephen R.

    2000-11-01

    Networking protocols for distributed collaborative ad-hoc wireless sensing are constrained by requirements such as energy efficiency, scalability, and support for greater variations in topology than traditional fully wired or last- hop wireless (remote to base station) networks. In such a highly constrained and dynamic environment, conventional networking approaches are generally not adequate. A declarative approach to network configuration and organization appears to offer significant benefits. Declarative networking exploits application-supplied data descriptions to control network routing and resource allocation in such a way as to enhance energy efficiency and scalability. An implementation of this approach, called the Declarative Routing Protocol (DRP) has been developed as part of DARPA's Sensor Information Technology program. This paper introduces the concept of declarative networking and what distinguishes it from more conventional networking approaches, describes the Declarative Routing Protocol, and presents performance results from initial experiments.

  3. 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

  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. PMID:27258013

  5. 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

  6. 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…

  7. 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.

  8. Shuttle-run synchronization in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Ma, Sheng-Fei; Bi, Hong-Jie; Zou, Yong; Liu, Zong-Hua; Guan, Shu-Guang

    2015-06-01

    In this work, we study the collective dynamics of phase oscillators in a mobile ad hoc network whose topology changes dynamically. As the network size or the communication radius of individual oscillators increases, the topology of the ad hoc network first undergoes percolation, forming a giant cluster, and then gradually achieves global connectivity. It is shown that oscillator mobility generally enhances the coherence in such networks. Interestingly, we find a new type of phase synchronization/clustering, in which the phases of the oscillators are distributed in a certain narrow range, while the instantaneous frequencies change signs frequently, leading to shuttle-run-like motion of the oscillators in phase space. We conduct a theoretical analysis to explain the mechanism of this synchronization and obtain the critical transition point.

  9. 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

  10. Robust message routing for mobile (wireless) ad hoc networks.

    SciTech Connect

    Goldsby, Michael E.; Johnson, Michael M.; Kilman, Dominique Marie; Bierbaum, Neal Robert; Chen, Helen Y.; Ammerlahn, Heidi R.; Tsang, Rose P.; Nicol, David M.

    2004-01-01

    This report describes the results of research targeting improvements in the robustness of message transport in wireless ad hoc networks. The first section of the report provides an analysis of throughput and latency in the wireless medium access control (MAC) layer and relates the analysis to the commonly used 802.11 protocol. The second section describes enhancements made to several existing models of wireless MAC and ad hoc routing protocols; the models were used in support of the work described in the following section. The third section of the report presents a lightweight transport layer protocol that is superior to TCP for use in wireless networks. In addition, it introduces techniques that improve the performance of any ad hoc source routing protocol. The fourth section presents a novel, highly scalable ad hoc routing protocol that is based on geographic principles but requires no localization hardware.

  11. Malicious node detection in ad-hoc wireless networks

    NASA Astrophysics Data System (ADS)

    Griswold, Richard L.; Medidi, Sirisha R.

    2003-07-01

    Advances in wireless communications and the proliferation of mobile computing devices has led to the rise of a new type of computer network: the ad-hoc wireless network. Ad-hoc networks are characterized by a lack of fixed infrastructure, which give ad-hoc networks a great deal of flexibility, but also increases the risk of security problems. In wired networks, key pieces of network infrastructure are secured to prevent unauthorized physical access and tampering. Network administrators ensure that everything is properly configured and are on-hand to fix problems and deal with intrusions. In contrast, the nodes in an ad-hoc network are responsible for routing and forwarding data in the network, and there are no network administrators to handle potential problems. This makes an ad-hoc network more vulnerable to a misconfigured, faulty, or compromised node. We propose a means for a node in an ad-hoc network to detect and handle these malicious nodes by comparing data available to the routing protocol, such as cached routes in Dynamic Source Routing, ICMP messages, and transport layer information, such as TCP timeouts. This data can then be used along with network probes to isolate the malicious node.

  12. 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

  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. Energy-Saving Topology Control for Heterogeneous Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Wang, Xuehui

    Topology control with per-node transmission power adjustment in wireless ad hoc networks has been shown to be effective with respect to prolonging network lifetime and increasing network capacity. In this paper, we propose a fully distributed, asynchronous and localized energy-saving topology control algorithm for heterogeneous ad hoc networks with non-uniform transmission ranges. We prove the topology derived from the algorithm preserves the network connectivity and bi-directionality. It need not the position system support and dramatically reduces the communication overhead compared to other topology control algorithms. Simulation results show the effectiveness of our proposed algorithm.

  15. Routing Protocol of Sparse Urban Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Li, Huxiong

    Vehicular ad hoc network (VANET) is an application of mobile ad hoc technology in transportation systems, it has become an important part of ITS. Since multi-hop link is hard to set up in sparse VANET, a traffic-aware routing (TAR) protocol is proposed which estimates vehicle average neighbors (VAN) of roads by exchanging beacon messages between encounter vehicles. Road with high VAN is preferred to be selected as part of forwarding path at intersection. Packets are forwarded to the next intersection in road in a greedy manner. Simulations show that TAR outperforms the compared protocols in terms of both packet delivery ratio and average end-to-end delay.

  16. 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…

  17. 14 CFR § 1203.1002 - Ad hoc committees.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Ad hoc committees. § 1203.1002 Section § 1203.1002 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION INFORMATION SECURITY PROGRAM Special Access Programs (SAP) and Sensitive Compartmented Information (SCI) Programs...

  18. Routing in Ad Hoc Network Using Ant Colony Optimization

    NASA Astrophysics Data System (ADS)

    Khanpara, Pimal; Valiveti, Sharada; Kotecha, K.

    The ad hoc networks have dynamic topology and are infrastructure less. So it is required to implement a new network protocol for providing efficient end to end communication based on TCP/IP structure. There is a need to re-define or modify the functions of each layer of TCP/IP model to provide end to end communication between nodes. The mobility of the nodes and the limited resources are the main reason for this change. The main challenge in ad hoc networks is routing. Due to the mobility of the nodes in the ad hoc networks, routing becomes very difficult. Ant based algorithms are suitable for routing in ad hoc networks due to its dynamic nature and adaptive behavior. There are number of routing algorithms based on the concept of ant colony optimizations. It is quite difficult to determine the best ant based algorithm for routing as these algorithms perform differently under various circumstances such as the traffic distribution and network topology. In this paper, the overview of such routing algorithms is given.

  19. Ad-hoc percutaneous coronary intervention and staged percutaneous coronary intervention.

    PubMed

    Rahman, Z; Paul, G K; Choudhury, A K

    2011-10-01

    Percutaneous coronary intervention (PCI) is a catheter based procedure where a catheter system is introduced through a systemic artery under local anesthesia in a stenotic coronary artery by controlled inflation of a distensible balloon. At early period, PCI was done in a separate session following coronary angiogram (Staged PCI) and it was more costly and hospital stay was long. As the expertization and laboratory facilities improved, the health care providers think about cost, hospital stay and patient convenience. So, to reduce the cost and patient preferred more PCI being done immediately following diagnostic catheterization (Ad-hoc PCI). Subsequently this Ad-hoc procedure becomes popular and now most of the PCI are Ad-hoc PCI worldwide. Rate of combined procedure (Ad-hoc) progressively increased from 54% in 1990 to 88% in 2000 with a significant decrease in rate of complications. In the initial study of Ad-hoc PCI suggested that Ad-hoc PCI should be done in selected group of patients as there was some potential risk factors (e.g. Multivessel diseases, unstable angina, aortic valve disease, and recent infarction or thrombolytic therapy) for Ad-hoc procedure and some (e.g. Older age, multivessel PTCA and complex lesion PTCA) for staged procedure. But recent studies showed that no significant difference in respect of safety and efficacy between Ad-hoc and staged PCI. Previous studies, in the era of balloon angioplasty from 1985 to 1995, Haraphonges et al. (1988), Rozenman et al. (1995) and Kimmel et al. (1997) suggested that an ad hoc approach is safe, with potentially more complications in patients with unstable angina pectoris or other high-risk factors. However, these reports have been limited to observational studies representing single institution experiences with small samples and inclusion of patients who underwent emergency PCI procedures. In Bangladesh a prospective observational study was done among 120 patients to compare the outcome of Ad-hoc and

  20. 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.

  1. Distributed Reinforcement Learning Approach for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Wu, Celimuge; Kumekawa, Kazuya; Kato, Toshihiko

    In Vehicular Ad hoc Networks (VANETs), general purpose ad hoc routing protocols such as AODV cannot work efficiently due to the frequent changes in network topology caused by vehicle movement. This paper proposes a VANET routing protocol QLAODV (Q-Learning AODV) which suits unicast applications in high mobility scenarios. QLAODV is a distributed reinforcement learning routing protocol, which uses a Q-Learning algorithm to infer network state information and uses unicast control packets to check the path availability in a real time manner in order to allow Q-Learning to work efficiently in a highly dynamic network environment. QLAODV is favored by its dynamic route change mechanism, which makes it capable of reacting quickly to network topology changes. We present an analysis of the performance of QLAODV by simulation using different mobility models. The simulation results show that QLAODV can efficiently handle unicast applications in VANETs.

  2. 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

  3. Auto-configuration protocols in mobile ad hoc networks.

    PubMed

    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

  4. MAC protocol for ad hoc networks using a genetic algorithm.

    PubMed

    Elizarraras, Omar; Panduro, Marco; Méndez, Aldo L; Reyna, Alberto

    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

  5. 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

  6. Load-aware Flooding for Streaming over Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Utsu, Keisuke; Ishii, Hiroshi

    This paper discusses the streaming of high rate media such as video or audio information over ad hoc networks in disaster situations or for temporary events when it is difficult to use fixed infrastructure. The conventional simple flooding is not applicable for this application because it generates a large number of redundant rebroadcast and heavy traffic load to the network. To restrain redundant rebroadcast messages, several methods have been proposed. But since those studies do not take into account the actual load condition at each node that will affect network efficiency, they cannot achieve both ensuring the high message reachability and reducing redundant rebroadcast. In this paper, we propose two novel load-aware flooding methods using the MAC transmission queue information at each node to make the decision about whether rebroadcast messages should be sent or not. Through network simulations, we evaluate and show the effectiveness of our proposals. The result shows that our proposals achieve both ensuring high message reachability and restraint of redundant rebroadcast comparing with existing methods.

  7. Design of the next generation cognitive mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Amjad, Ali; Wang, Huiqiang; Chen, Xiaoming

    Cognition capability has been seen by researchers as the way forward for the design of next generation of Mobile Ad Hoc Networks (MANETs). The reason why a cognitive paradigm would be more suited to a MANET is because MANETs are highly dynamic networks. The topology may change very frequently during the operation of a MANET. Traffic patterns in MANETs can vary from time to time depending on the need of the users. The size of a MANET and node density is also very dynamic and may change without any predictable pattern. In a MANET environment, most of these parameters may change very rapidly and keeping track of them manually would be very difficult. Previous studies have shown that the performance of a certain routing approach in MANETs is dependent on the size of the network and node density. The choice of whether to use a reactive or proactive routing approach comes down to the network size parameter. Static or offline approaches to fine tune a MANET to achieve certain performance goals is hence not very productive as a lot of these parameters keep changing during the course of operation of MANETs. Similarly, the performance of MANETs would improve greatly if the MAC layer entity could operate in a more flexible manner. In this paper we propose a cognitive MANET design that will ensure that all these dynamic parameters are automatically monitored and decisions are based on the current status of these parameters.

  8. 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..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  10. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  11. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  12. 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..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Kumar, Sumit; Mehfuz, Shabana

    2016-08-01

    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).

  19. 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

  20. 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.

  1. Opportunistic Channel Scheduling for Ad Hoc Networks with Queue Stability

    NASA Astrophysics Data System (ADS)

    Dong, Lei; Wang, Yongchao

    2015-03-01

    In this paper, a distributed opportunistic channel access strategy in ad hoc network is proposed. We consider the multiple sources contend for the transmission opportunity, the winner source decides to transmit or restart contention based on the current channel condition. Owing to real data assumption at all links, the decision still needs to consider the stability of the queues. We formulate the channel opportunistic scheduling as a constrained optimization problem which maximizes the system average throughput with the constraints that the queues of all links are stable. The proposed optimization model is solved by Lyapunov stability in queueing theory. The successive channel access problem is decoupled into single optimal stopping problem at every frame and solved with Lyapunov algorithm. The threshold for every frame is different, and it is derived based on the instantaneous queue information. Finally, computer simulations are conducted to demonstrate the validity of the proposed strategy.

  2. Indoor Positioning - An Ad-Hoc Positioning System

    NASA Astrophysics Data System (ADS)

    Mautz, Rainer

    2008-06-01

    The aim of this paper is to discuss the development of an automatic, low-cost system that exploits current or near future wireless communications technology to enable continuous tracking of the location of devices in all environments. The development of such a wireless sensor network involves system design, digital signal processing, protocol development, extraction of ranges and localisation. This paper focuses on the user requirements, system architecture and network positioning. The user requirements are presented with a focus on applications in geodesy. A high level strategy for the positioning function is presented based on an ad-hoc geodetic network positioning method including issues of accuracy, quality and reliability of the node positions. Results show that it is possible to achieve a position deviation that is of the size of the ranging error.

  3. 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.

  4. Realistic Mobility Modeling for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Akay, Hilal; Tugcu, Tuna

    2009-08-01

    Simulations used for evaluating the performance of routing protocols for Vehicular Ad Hoc Networks (VANET) are mostly based on random mobility and fail to consider individual behaviors of the vehicles. Unrealistic assumptions about mobility produce misleading results about the behavior of routing protocols in real deployments. In this paper, a realistic mobility modeling tool, Mobility for Vehicles (MOVE), which considers the basic mobility behaviors of vehicles, is proposed for a more accurate evaluation. The proposed model is tested against the Random Waypoint (RWP) model using AODV and OLSR protocols. The results show that the mobility model significantly affects the number of nodes within the transmission range of a node, the volume of control traffic, and the number of collisions. It is shown that number of intersections, grid size, and node density are important parameters when dealing with VANET performance.

  5. Maximizing the Effective Lifetime of Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Hossain, M. Julius; Dewan, M. Ali Akber; Chae, Oksam

    This paper presents a new routing approach to extend the effective lifetime of mobile ad hoc networks (MANET) considering both residual battery energy of the participating nodes and routing cost. As the nodes in ad hoc networks are limited in power, a power failure occurs if a node has insufficient remaining energy to send, receive or forward a message. So, it is important to minimize the energy expenditure as well as to balance the remaining battery power among the nodes. Cost effective routing algorithms attempt to minimize the total power needed to transmit a packet which causes a large number of nodes to loose energy quickly and die. On the other hand, lifetime prediction based routing algorithms try to balance the remaining energies among the nodes in the networks and ignore the transmission cost. These approaches extend the lifetime of first few individual nodes. But as nodes spend more energy for packet transfer, power failures occurs, within short interval resulting more number of total dead node earlier. This reduces the effective lifetime of the network, as at this stage successful communication is not possible due to the lack of forwarding node. The proposed method keeps the transmission power in modest range and at the same time tries to reduce the variance of the residual energy of the nodes more effectively to obtain the highest useful lifetime of the networks in the long run. Nonetheless, movement of nodes frequently creates network topology changes via link breaks and link creation and thus effects on the stability of the network. So, the pattern of the node movement is also incorporated in our route selection procedure.

  6. Data Security in Ad Hoc Networks Using Randomization of Cryptographic Algorithms

    NASA Astrophysics Data System (ADS)

    Krishna, B. Ananda; Radha, S.; Keshava Reddy, K. Chenna

    Ad hoc networks are a new wireless networking paradigm for mobile hosts. Unlike traditional mobile wireless networks, ad hoc networks do not rely on any fixed infrastructure. Instead, hosts rely on each other to keep the network connected. The military tactical and other security-sensitive operations are still the main applications of ad hoc networks, although there is a trend to adopt ad hoc networks for commercial uses due to their unique properties. One main challenge in design of these networks is how to feasibly detect and defend the major attacks against data, impersonation and unauthorized data modification. Also, in the same network some nodes may be malicious whose objective is to degrade the network performance. In this study, we propose a security model in which the packets are encrypted and decrypted using multiple algorithms where the selection scheme is random. The performance of the proposed model is analyzed and it is observed that there is no increase in control overhead but a slight delay is introduced due to the encryption process. We conclude that the proposed security model works well for heavily loaded networks with high mobility and can be extended for more cryptographic algorithms.

  7. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  8. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  9. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  10. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  11. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  12. Z306 molecular contamination ad hoc committee results

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.

    1992-01-01

    LDEF external surfaces which did not receive significant amounts of atomic oxygen were observed to be coated with a brown contamination, apparently the result of a condensed organic residue darkened due to UV radiation exposure. During the initial Materials Special Investigation Group (MSIG) Meeting after LDEF deintegration, held in Seattle - July 1990, this organic contamination was the subject of much discussion. The amount of contamination was thought to be significant and its source was immediately believed to be the Z306 black thermal control coating used to coat the entire inner surface of LDEF. Due to the size of the structure, it was not feasible to bake-out the coating. However, initial data on the contamination film was confusing in that significant amounts of silicon was observed by several different researchers. Silicon (from silicone) was not expected to be a potential outgassing product of the Z306 polyurethane coating. To investigate the connection between external contamination and the interior paint, a MSIG ad hoc committee was formed.

  13. Managing performance of DB2 Ad Hoc Reports

    SciTech Connect

    Chow, A.

    1994-02-01

    The DB2 financial reporting systems at Westinghouse Savannah River Company consists of 212 standardized reports that over 1034 users have accessed in 1993 to generate their reports. Each report has a range of selection criteria that the users can specify. Depending on the selection criteria, a report can access from a few rows to millions of rows of data. When this new DB2 system went into production in 1992, the CPU was at 100% utilization. From the beginning, ad hoc reports had a backlog of 4--5 days. Since DB2 was a new DBMS, most people blamed the poor report turn around times on DB2 as an inefficient DBMS and on a shortage of CPU cycles. Since we are unable to purchase a more powerful CPU, the only option left to us was to improve report turn around was system and application performance tuning. This document presents our efforts in these areas. Education of users in report submission was a starting point. And as to index tuning techniques that were applied, we created more friendly indexes, used clustering indexes, and used a reorganizing mechanism. A more efficient SQL was written which saved a lot of money.

  14. Algorithmic aspects of topology control problems for ad hoc networks

    SciTech Connect

    Liu, R.; Lloyd, E. L.; Marathe, M. V.; Ramanathan, R.; Ravi, S. S.

    2002-01-01

    Topology control problems are concerned with the assignment of power values to nodes of an ad hoc network so that the power assignment leads to a graph topology satisfying some specified properties. This paper considers such problems under several optimization objectives, including minimizing the maximum power and minimizing the total power. A general approach leading to a polynomial algorithm is presented for minimizing maximum power for a class of graph properties, called monotone properties. The difficulty of generalizing the approach to properties that are not monoione is pointed out. Problems involving the minimization of total power are known to be NP-complete even for simple graph properties. A general approach that leads to an approximation algorithm for minimizing the total power for some monotone properties is presented. Using this approach, a new approximation algorithm for the problem of minimizing the total power for obtaining a 2-node-connected graph is obtained. It is shown that this algorithm provides a constant performance guarantee. Experimental results from an implementation of the approximation algorithm are also presented.

  15. 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.

  16. Detecting and isolating malicious nodes in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Li, Fanzhi; Jassim, Sabah

    2007-04-01

    Malicious nodes can seriously impair the performance of wireless ad hoc networks as a result of different actions such as packet dropping. Secure routes are shortest paths on which every node on the route is trusted even if unknown. Secure route discovery requires the adoption of mechanisms of associating trust to nodes. Most existing secure route discovery mechanisms rely on shared keys and digital signature. In the absence of central nodes that act as certification authority, such protocols suffer from heavy computational burden and are vulnerable to malicious attacks. In this paper we shall review existing techniques for secure routing and propose to complement route finding with creditability scores. Each node would have a credit list for its neighbors. Each node monitors its neighbors' pattern of delivering packets and regularly credits are reviewed and updated accordingly. Unlike most existing schemes the focus of our work is based on post route discovery stage, i.e. when packets are transmitted on discovered routes. The level of trust in any route will be based on the credits associated with the neighbors belonging to the discovered route. We shall evaluate the performance of the proposed scheme by modifying our simulation system so that each node has a dynamic changing "credit list" for its neighbors' behavior. We shall conduct a series of simulations with and without the proposed scheme and compare the results. We will demonstrate that the proposed mechanism is capable of isolating malicious nodes and thereby counteracting black hole attacks.

  17. 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

  18. In search of reflective behavior and shared understanding in ad hoc expert teams.

    PubMed

    Mulder, Ingrid; Swaak, Janine; Kessels, Joseph

    2004-04-01

    The work reported on here concentrates on virtual ad hoc expert teams for the integration of learning and working, as ad hoc teams seem to be one way to cope with complexity in a knowledge-intensive society. In order to let ad hoc teams learn and work together, group members require effective communication and shared understanding among each other. Two empirical studies were conducted to study collaborative learning and shared understanding, one exploratory study and one experiment. In the first study, it was explored how virtual design teams work and learn together. Based on conceptual ideas, collaborative learning and shared understanding were observed and assessed in a design team over a period of four months. It was concluded that shared understanding was suboptimal; mainly due to the effect that hardly any questions were raised and answered. The second study elaborates on the need to encourage question-answer patterns and reflective behavior in such teams. A tool was developed that supported questioning behavior. As it was hypothesized that this tool leads to better questioning behavior, which in turn results in more reflective behavior and in increased shared understanding, an experiment was conducted. In the exploratory study, as well as in the experimental study, the perceived shared understanding increased over time. However, in both studies suboptimal questioning behavior and little reflective activity were noticed. The main results of the two empirical studies are compared and discussed. PMID:15140358

  19. 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…

  20. A Token Ring Protocol for Dynamic Ad-hoc Wireless Environments

    SciTech Connect

    Top, P; Kohlhepp, V; Dowla, F

    2005-09-30

    A wireless ad-hoc networking protocol is presented. The protocol is designed to be flexible, easy to use and adaptable to a wide variety of potential applications. The primary considerations in design are small code size, guaranteed bandwidth access, limited delay, and error resilience in a highly dynamic ad-hoc environment. These considerations are achieved through the use of token ring protocol.

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

    PubMed

    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

  2. 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

  3. VoIP Implementation and Experiments on a Mobile Wireless AdHoc Network

    NASA Astrophysics Data System (ADS)

    Zhang, Hongqi; Yang, Oliver; Zhao, Jiying

    We have implemented a testbed to study the performance of VoIP in wireless ad hoc networks. The ASNC (Adaptive Source Network-rate Control) scheme is used to battle packet loss by feeding MOS (Mean Opinion Score) and loss information back to the sender. Our different VoIP experiments with measurements on delay, packet loss rate and MOS have validated the feasibility and efficiency of our scheme. It further verifies the simulator we used in the initial investigation.

  4. Enhancements for distributed certificate authority approaches for mobile wireless ad hoc networks.

    SciTech Connect

    Van Leeuwen, Brian P.; Michalski, John T.; Anderson, William Erik

    2003-12-01

    Mobile wireless ad hoc networks that are resistant to adversarial manipulation are necessary for distributed systems used in military and security applications. Critical to the successful operation of these networks, which operate in the presence of adversarial stressors, are robust and efficient information assurance methods. In this report we describe necessary enhancements for a distributed certificate authority (CA) used in secure wireless network architectures. Necessary cryptographic algorithms used in distributed CAs are described and implementation enhancements of these algorithms in mobile wireless ad hoc networks are developed. The enhancements support a network's ability to detect compromised nodes and facilitate distributed CA services. We provide insights to the impacts the enhancements will have on network performance with timing diagrams and preliminary network simulation studies.

  5. Does Ad Hoc Coronary Intervention Reduce Radiation Exposure? – Analysis of 568 Patients

    PubMed Central

    Truffa, Márcio A. M.; Alves, Gustavo M.P.; Bernardi, Fernando; Esteves Filho, Antonio; Ribeiro, Expedito; Galon, Micheli Z.; Spadaro, André; Kajita, Luiz J.; Arrieta, Raul; Lemos, Pedro A.

    2015-01-01

    Background Advantages and disadvantages of ad hoc percutaneous coronary intervention have been described. However little is known about the radiation exposure of that procedure as compared with the staged intervention. Objective To compare the radiation dose of the ad hoc percutaneous coronary intervention with that of the staged procedure Methods The dose-area product and total Kerma were measured, and the doses of the diagnostic and therapeutic procedures were added. In addition, total fluoroscopic time and number of acquisitions were evaluated. Results A total of 568 consecutive patients were treated with ad hoc percutaneous coronary intervention (n = 320) or staged percutaneous coronary intervention (n = 248). On admission, the ad hoc group had less hypertension (74.1% vs 81.9%; p = 0.035), dyslipidemia (57.8% vs. 67.7%; p = 0.02) and three-vessel disease (38.8% vs. 50.4%; p = 0.015). The ad hoc group was exposed to significantly lower radiation doses, even after baseline characteristic adjustment between both groups. The ad hoc group was exposed to a total dose-area product of 119.7 ± 70.7 Gycm2, while the staged group, to 139.2 ± 75.3 Gycm2 (p < 0.001). Conclusion Ad hoc percutaneous coronary intervention reduced radiation exposure as compared with diagnostic and therapeutic procedures performed at two separate times. PMID:26351982

  6. Ad hoc CubeSat constellations: Secondary launch coverage and distribution

    NASA Astrophysics Data System (ADS)

    Marinan, A.; Nicholas, A.; Cahoy, K.

    The primary purpose of a constellation is to obtain global measurements with improved spatial and temporal resolution. The small size, low cost, standardized form factor, and increasing availability of commercial parts for CubeSats make them ideal for use in constellations. However, without taking advantage of secondary payload opportunities, it would be costly to launch and distribute a CubeSat constellation into a specific configuration. A cost-effective way to launch a constellation of CubeSats is via consecutive secondary payload launch opportunities, but the resulting constellation would be an ad hoc mix of orbit parameters. We focus on the feasibility of cobbling together constellation-like functionality from multiple secondary payload opportunities. Each participating CubeSat (or set of CubeSats) per launch could have completely different orbital parameters, even without propulsion onboard the CubeSats or intermediate transfer carriers. We look at the ground coverages that could be obtained for a constellation of five to six orbital planes with one to six satellites in each plane. We analyze past and announced future launch opportunities for CubeSats, including launch platforms supported by the NASA Educational Launch of Nanosatellites (ELaNa). We consider combinations of possible launch locations and temporal spacings over the course of one year and simulate the resulting ground coverage patterns and revisit times for an ad hoc constellation using these launch opportunities. We perform this analysis for two separate case studies - one with only US launches and one with both US and non-US opportunities - and vary the number of satellites per orbital plane. Typical CubeSat mission lifetimes and deorbit times for low-altitude orbits are included in these analyses. The ad hoc constellation results are compared to coverage from uniformly-placed LEO constellations and are quantified in terms of revisit time, time to 100% global coverage, and response time. For mu

  7. 75 FR 33838 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... Parham, Exploration Systems Mission Directorate, National Aeronautics and Space Administration... SPACE ADMINISTRATION NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION: Notice of Meeting. SUMMARY: In accordance with...

  8. 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

  9. Design of multilevel heterogeneous ad-hoc wireless networks with UAVs

    NASA Astrophysics Data System (ADS)

    Gu, Daniel L.; Gerla, Mario; Ly, Henry; Xu, Kaixin; Kong, Jiejun; Hong, Xiaoyan

    2001-10-01

    Multi-Layer Ad Hoc Wireless Networks with UAVs is an ideal infrastructure to establish a rapidly deployable wireless communication system any time any where in the world for military applications. In this paper, we review the research we have done so far for our heterogeneous solution. First of all, we proposed the infrastructure of Multi-level Heterogeneous Ad-Hoc Wireless Network with UAVs. Second, we developed a new MAC layer protocol, Centralized Intelligent Channel Assigned Multiple Access (C-ICAMA), for ground mobile backbone nodes to access UAV. Third, we extended HSR (Hierarchical State Routing) to this Multi-Level Heterogeneous Ad-Hoc Wireless Network. Due to the intrinsic limitations of Extended HSR, we extended the Landmark Ad Hoc Routing (LANMAR) as our forth step. Security is a critical issue for mobile ad-hoc wireless networks, especially for military applications. We developed an embedded distributed security protocol and integrated with this heterogeneous hierarchical ad hoc wireless networks in our fifth step. Therefore, the hierarchical multi-layer approach is the most desirable approach to achieve routing scalability in multi-hop wireless networks.

  10. Soil Property Mapping Over Large Areas Using Sparse Ad-hoc Samples

    NASA Astrophysics Data System (ADS)

    Zhu, A.; Liu, J.

    2011-12-01

    Information on spatial variation of soil properties over large areas is a critical input for environmental modeling at large scales. Yet, quality information on soil spatial variation over large areas is difficult to obtain due to the large number of field samples required. Existing samples are often sparse and ad-hoc. The soil property maps created from these samples using existing techniques are not only at low quality but also lack the uncertainty information. This paper presents a new approach to map soil properties and quantify uncertainty in the derived soil property maps over large areas using sparse and ad-hoc samples. The underlying assumption of this new approach is the soil-landscape concept which stipulates that the more similar the environment conditions between two locations the more similar the soil property values are between the two sites. Under this assumption each sample can be considered as a representative over areas of similar environmental conditions. The level of representation of an individual sample for an unsampled location can be approximated by the similarity between their respective environment conditions. Based on this "individual representation" concept and with a Case-based Reasoning (CBR) approach soil property values at unsampled locations can be predicted and the uncertainty associated with each prediction can also be quantified based on their environmental similarity to individual samples. A case study over the Illy Region, a 50,000 km2 area in Xinjiang, Northwest China, has demonstrated that the approach can be an effective alternative for mapping soil property and quantifying uncertainty over large areas with sparse and ad-hoc samples.

  11. 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.

  12. 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.

  13. 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.

  14. Routing in wireless ad hoc and sensor network underground with sensor data in real-time

    NASA Astrophysics Data System (ADS)

    Odei-Lartey, Emmanuel; Hartmann, Klaus; Ahmadian, Hamidreza

    2012-05-01

    This paper first describes the innovative topology and structure of a wireless ad hoc and sensor network in a so called line-in-the-underground formation and the feasibility of achieving a reliable wireless connection underground with regards to a borehole telemetry system. It further describes a routing algorithm/protocol implementation based on a modification of the ad hoc on-demand distance vector protocol to achieve a reliable underground communication scheme for the wireless ad hoc network deployed underground for sensor data acquisition in real time as applied in the borehole telemetry system. Simulations and experiments are conducted to investigate and verify the effectiveness of this routing technique and the performance results are shown.

  15. Time geography for ad-hoc shared-ride trip planning in mobile geosensor networks

    NASA Astrophysics Data System (ADS)

    Raubal, Martin; Winter, Stephan; Teβmann, Sven; Gaisbauer, Christian

    Ad-hoc shared-ride trip planning in an urban environment is a complex task within a non-deterministic transportation network. Mobile geosensor networks provide the technical environment for realizing ad-hoc shared-ride trip planning: Network nodes are autonomous agents that interact locally by ad-hoc short-range communication and arrange for shared rides. In a mobile geosensor network, communication costs are critical because of constraints regarding bandwidth, available energy, and memory. This paper introduces spatio-temporal concepts from time geography, which can be employed during the planning process to significantly reduce communication costs. We will integrate network-based algorithms and different wayfinding strategies to assist both shared-ride clients and hosts in finding optimal travel assignments. Multi-agent geosimulation in a real street network is used to demonstrate the applicability of the approach and quantitatively confirm the theoretically foreseen reduction in communication costs.

  16. Fuzzy Multiple Metrics Link Assessment for Routing in Mobile Ad-Hoc Network

    NASA Astrophysics Data System (ADS)

    Soo, Ai Luang; Tan, Chong Eng; Tay, Kai Meng

    2011-06-01

    In this work, we investigate on the use of Sugeno fuzzy inference system (FIS) in route selection for mobile Ad-Hoc networks (MANETs). Sugeno FIS is introduced into Ad-Hoc On Demand Multipath Distance Vector (AOMDV) routing protocol, which is derived from its predecessor, Ad-Hoc On Demand Distance Vector (AODV). Instead of using the conventional way that considering only a single metric to choose the best route, our proposed fuzzy decision making model considers up to three metrics. In the model, the crisp inputs of the three parameters are fed into an FIS and being processed in stages, i.e., fuzzification, inference, and defuzzification. Finally, after experiencing all the stages, a single value score is generated from the combination metrics, which will be used to measure all the discovered routes credibility. Results obtained from simulations show a promising improvement as compared to AOMDV and AODV.

  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. Deny-by-Default Distributed Security Policy Enforcement in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Alicherry, Mansoor; Keromytis, Angelos D.; Stavrou, Angelos

    Mobile Ad-hoc Networks (MANETs) are increasingly employed in tactical military and civil rapid-deployment networks, including emergency rescue operations and ad hoc disaster-relief networks. However, this flexibility of MANETs comes at a price, when compared to wired and base station-based wireless networks: MANETs are susceptible to both insider and outsider attacks. This is mainly because of the lack of a well-defined defense perimeter preventing the effective use of wired defenses including firewalls and intrusion detection systems.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Tang, Ken; Gerla, Mario

    2001-07-01

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

  1. Effective Route Maintenance and Restoration Schemes in Mobile Ad Hoc Networks

    PubMed Central

    Kang, Byung-Seok; Ko, In-Young

    2010-01-01

    This study proposes a location-based hybrid routing protocol to improve data packet delivery and to reduce control message overhead in mobile ad hoc networks. In mobile environments, where nodes move continuously at a high speed, it is generally difficult to maintain and restore route paths. Therefore, this study suggests a new flooding mechanism to control route paths. The essence of the proposed scheme is its effective tracking of the destination’s location based on the beacon messages of the main route nodes. Through experiments based on an NS-2 simulator, the proposed scheme shows improvements in the data packet delivery ratio and reduces the amount of routing control message overhead compared with existing routing protocols such as AODV, LAR, ZRP and AODV-DFR. PMID:22315570

  2. 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.

  3. 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

  4. Energy-efficient distributed constructions of miniumum spanning tree for wireless ad-hoc networks

    SciTech Connect

    Kumar, V. S. A.; Pandurangan, G.; Khan, M.

    2004-01-01

    The Minimum Spanning Tree (MST) problem is one of the most important and commonly occurring primitive in the design and operation of data and communication networks. While there a redistributed algorithms for the MST problem these require relatively large number of messages and time, and are fairly involved, require synchronization and a lot of book keeping; this makes these algorithms impractical for emerging technologies such as ad hoc and sensor networks. In such networks, a sensor has very limited power, and any algorithm needs to be simple, local and energy efficient for being practical. Motivated by these considerations, we study the performance of a class of simple and local algorithms called Nearest Neighbor Tree (NNT) algorithms for energy-efficient construction of MSTs in a wireless ad hoc setting. These employ a very simple idea to eliminate the work involved in cycle detection in other MST algorithms: each node chooses a distinct rank, and connects to the closest node of higher rank. We consider two variants of the NNT algorithms, obtained by two ways of choosing the ranks: (i) Random NNT, in which each node chooses a rank randomly, and (ii) Directional NNT, in which each node uses directional information for choosing the rank. We show provable bounds on the performance of these algorithms in instances obtained by uniformly distributed points in the unit square. Finally, we perform extensive simulations of our algorithms. We tested our algorithms on both uniformly random distributions of points, and on realistic distributions of points in an urban setting. The cost of the tree found by the NNT algorithms is within a factor of 2 of the MST, but there is more than a ten-fold saving on the energy and about a five fold saving on the number of messages sent. Also, our algorithms are significantly simpler to implement compared to, for instance, the GHS algorithm, which is essentially optimal with regards to the message complexity. Thus, our results

  5. 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…

  6. 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…

  7. Report of the Council for Exceptional Children's Ad Hoc Committee on Medically Fragile Students.

    ERIC Educational Resources Information Center

    Council for Exceptional Children, Reston, VA.

    New opportunities are available for students with special health care needs requiring specialized technological health care procedures for life support and/or health support, and attention to appropriate educational programs is required. Guidelines proposed by the Council for Exceptional Children's Ad Hoc Committee on Medically Fragile Students…

  8. Final Report of the IAG AD Hoc Working Group on Global Change

    NASA Technical Reports Server (NTRS)

    Dickey, Jean O.

    1995-01-01

    None given. Paper gives final report of the IAG ad hoc working group on global change. They made three main recommendations to the group: 1. the post of and IAG liaison or representative to the IGBP should be established. 2. A new core program,.

  9. 75 FR 43565 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-26

    ... SPACE ADMINISTRATION NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION: Notice of meeting. SUMMARY: In accordance with the Federal Advisory Committee Act, Public Law 92-463, as amended, the National Aeronautics and...

  10. 75 FR 15742 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-30

    ... SPACE ADMINISTRATION NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION: Notice of meeting. SUMMARY: In accordance with the Federal Advisory Committee Act, Public Law 92-463, as amended, the National Aeronautics and...

  11. 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…

  12. Should the University of Wisconsin-Eau Claire Seek NCATE Reaccreditation in 1983? Report of the Ad Hoc NCATE Study Committee.

    ERIC Educational Resources Information Center

    Whooley, John; And Others

    A study by the School of Education at the University of Wisconsin at Eau Claire (UWEC) was designed to provide information on whether UWEC should seek NCATE (National Council of Accreditation for Teacher Education) reaccreditation for its graduate and undergraduate teacher education programs in 1983. The essential question in the study was whether…

  13. 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…

  14. 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…

  15. Integrating Overlay Protocols for Providing Autonomic Services in Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Gouvas, Panagiotis; Zafeiropoulos, Anastasios; Liakopoulos, Athanassios; Mentzas, Gregoris; Mitrou, Nikolas

    Next generation network characteristics increase the complexity in the design and provision of advanced services, making inappropriate the selection of traditional approaches. Future networks are becoming larger in scale, more dynamic and more heterogeneous. In order to cope with these requirements, services are expected to adapt to environmental conditions and require minimum human intervention. In this paper a new model for providing autonomous and decentralized services is proposed, especially focusing on mobile ad hoc networks (MANETs). Using a newly proposed four-layered approach, service development may be realized independently from the underlying physical network. In a reference implementation, it is demonstrated that it is possible to set up an overlay network that hides any network changes from the service layer. Multiple mechanisms have been adapted in order to efficiently — in terms of message exchanges and convergence time — operate over an ad hoc environment. Finally, it is demonstrated that a specific service could operate over a dynamic network with multiple failures.

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

    PubMed

    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

  17. Scope of practice in audiology. Ad Hoc Committee on scope of Practice in Audiology.

    PubMed

    1996-01-01

    This scope of practice in audiology statement is an official policy of the American Speech-Language Hearing Association (ASHA). The document was developed by the ASHA Ad Hoc Committee on the Scope of Practice in Audiology and approved in 1995 by the Legislative Council (8-95). Members of the ad hoc committee include David Wark (chair), Tamara Adkins, J. Michael Dennis, Dana L. Oviatt, Lori Williams, and Evelyn Cherow (ex officio). Lawrence Higdon, ASHA vice president for professional practices in audiology, served as monitoring vice president. This statement supersedes the Scope of Practice, Speech-Language Pathology and Audiology statement (LC 6-89), Asha, April 1990, 1-2. PMID:8680260

  18. PNNI routing support for ad hoc mobile networking: The multilevel case

    SciTech Connect

    Martinez, L.; Sholander, P.; Tolendino, L.

    1998-01-01

    This contribution extends the Outside Nodal Hierarchy List (ONHL) procedures described in ATM Forum Contributions 97-0766 and 97-0933. These extensions allow multiple mobile networks to form either an ad hoc network or an extension of a fixed PNNI infrastructure. A previous contribution (97-1073) covered the simplest case where the top-most Logical Group Nodes (LGNs), in those mobile networks, all resided at the same level in a PNNI hierarchy. This contribution covers the more general case wherein those top-most LGNs may reside at different PNNI hierarchy levels. Both of the SNL contributions consider flat ad hoc network architectures in the sense that each mobile network always participates in the PNNI hierarchy at the pre-configured level of its top-most LGN.

  19. The Ad Hoc process to strengthen the framework convention on climate change

    SciTech Connect

    Ramakrishna, K.; Deutz, A.M.; Jacobsen, L.A.

    1995-11-01

    The Woods Hole Research Center convened an International Conference on The Ad Hoc Process to Strengthen the Framework Convention on Climate Change in Woods Hole, MA, on October 7-9, 1995. The conference was conducted to examine the prospects for successful adoption of a protocol to the Framework Convention on Climate Change by 1997. In preparation for the Second session of the Ad Hoc Group on the Berlin Mandate, several governmental and nongovernmental representatives met in Woods Hole to discuss the process and possible outcome of the Berlin Mandate negotiations for a protocol or other legal instrument to strengthen the Convention. The conference was by invitation and all participants attended in their personal capacities.

  20. 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.

  1. PNNI routing support for ad hoc mobile networking: A flat architecture

    SciTech Connect

    Martinez, L.; Sholander, P.; Tolendino, L.

    1997-12-01

    This contribution extends the Outside Nodal Hierarchy List (ONHL) procedures described in ATM Form Contribution 97-0766. These extensions allow multiple mobile networks to form either an ad hoc network or an extension of a fixed PNNI infrastructure. This contribution covers the simplest case where the top-most Logical Group Nodes (LGNs), in those mobile networks, all reside at the same level in a PNNI hierarchy. Future contributions will cover the general case where those top-most LGNs reside at different hierarchy levels. This contribution considers a flat ad hoc network architecture--in the sense that each mobile network always participates in the PNNI hierarchy at the preconfigured level of its top-most LGN.

  2. Upper Bounding Service Capacity in Multihop Wireless SSMA-Based Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Du, Shirong; Daigle, John N.; Alidaee, Bahram

    Upper bounds on the service carrying capacity of a multihop, wireless, SSMA-based ad hoc network are considered herein. The network has a single radio band for transmission and reception. Each node can transmit to, or receive from, multiple nodes simultaneously. We formulate the scheduling of transmissions and control of transmit powers as a joint, mixed-integer, nonlinear optimization problem that yields maximum return at minimum power subject to SINR constraints. We present an efficient tabu search-based heuristic algorithm to solve the optimization problem and rigorously assess the quality of the results. Through analysis and simulation, we establish upper bounds on the VoIP call carrying capacity of the network as function of various parameters. We discuss the pros and cons of using SSMA as a spectrum sharing technique in wireless ad hoc networks

  3. Adhoc: an R package to calculate ad hoc distance thresholds for DNA barcoding identification.

    PubMed

    Sonet, Gontran; Jordaens, Kurt; Nagy, Zoltán T; Breman, Floris C; De Meyer, Marc; Backeljau, Thierry; Virgilio, Massimiliano

    2013-12-30

    Identification by DNA barcoding is more likely to be erroneous when it is based on a large distance between the query (the barcode sequence of the specimen to identify) and its best match in a reference barcode library. The number of such false positive identifications can be decreased by setting a distance threshold above which identification has to be rejected. To this end, we proposed recently to use an ad hoc distance threshold producing identifications with an estimated relative error probability that can be fixed by the user (e.g. 5%). Here we introduce two R functions that automate the calculation of ad hoc distance thresholds for reference libraries of DNA barcodes. The scripts of both functions, a user manual and an example file are available on the JEMU website (http://jemu.myspecies.info/computer-programs) as well as on the comprehensive R archive network (CRAN, http://cran.r-project.org). PMID:24453565

  4. Adhoc: an R package to calculate ad hoc distance thresholds for DNA barcoding identification

    PubMed Central

    Sonet, Gontran; Jordaens, Kurt; Nagy, Zoltán T.; Breman, Floris C.; De Meyer, Marc; Backeljau, Thierry; Virgilio, Massimiliano

    2013-01-01

    Abstract Identification by DNA barcoding is more likely to be erroneous when it is based on a large distance between the query (the barcode sequence of the specimen to identify) and its best match in a reference barcode library. The number of such false positive identifications can be decreased by setting a distance threshold above which identification has to be rejected. To this end, we proposed recently to use an ad hoc distance threshold producing identifications with an estimated relative error probability that can be fixed by the user (e.g. 5%). Here we introduce two R functions that automate the calculation of ad hoc distance thresholds for reference libraries of DNA barcodes. The scripts of both functions, a user manual and an example file are available on the JEMU website (http://jemu.myspecies.info/computer-programs) as well as on the comprehensive R archive network (CRAN, http://cran.r-project.org). PMID:24453565

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

    SciTech Connect

    Aouassa, M.; Berbezier, I.; Favre, L.; Ronda, A.; Bollani, M.; Sordan, R.; Delobbe, A.; Sudraud, P.

    2012-07-02

    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-high 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.

  6. 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.

  7. 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

  8. Analysis and Proposal of Position-Based Routing Protocols for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Okada, Hiraku; Takano, Akira; Mase, Kenichi

    One of the most promising applications of a mobile ad hoc network is a vehicular ad hoc network (VANET). Each vehicle is aware of its position information by GPS or other methods, so position-based routing is a useful approach in VANET. The position-based routing protocol can be classified roughly into a next-hop forwarding method and a directed flooding method. We evaluate performance of both methods by analytic approach and compare them in this paper. From the evaluation results, we conclude that it is effective for the position-based routing to choose either the next-hop forwarding method or the directed flooding method according to the environment. Then we propose the hybrid transmission method which can select one of them according to the environment, and clarify that the proposed method can keep the packet delivery ratio at a high level and reduce the delay time.

  9. Vehicular ad hoc network for a surveillance system using multifrequency band enhancement

    NASA Astrophysics Data System (ADS)

    Bunruangses, Montree; Sunat, Khamron; Mitatha, Somsak; Yupapin, Preecha P.

    2010-09-01

    We present a new design of a surveillance system via a vehicular ad hoc network (VANET) integrated by a 3-G or 4-G cellular wireless network. We propose dense wavelength division multiplexing wavelength enhancement for increasing the channel capacity and signal security. Increase in the number of channels can be obtained by increasing the wavelength density. Signal security is introduced by a specific wavelength filter controlled by the central operator. Optical communication wavelength enhancement is reviewed. The advantage of this proposed system is that it can easily be implemented and incorporated into the existing communication link in either a cellular or ad hoc wireless system, where signal security and hence privacy can be provided.

  10. RHINO: armoured plated networking with intelligent high speed wireless ad hoc capability

    NASA Astrophysics Data System (ADS)

    Markarian, Garik; Singh, Farid

    2008-04-01

    This paper describes the concept of an intelligent high speed wireless ad-hoc network, which is currently being developed. The technology aims at, not replacing any of the existing standards, but aims to complement them in urban, military and hazardous environments. Known as Rhino, the technology is a platform independent, IP based network which will provide adequate bandwidth for real time video, audio and data traffic. The technology and specifications described in this paper are based on initial development of the technology.

  11. EGPS: An Efficient Privacy Preserving Scheme for Vehicular ad hoc Networks

    NASA Astrophysics Data System (ADS)

    Zhao, Baokang; Su, Xiangyu; Su, Jinshu; Song, Ziming; Sun, Yipin; Tao, Jing; Tang, Yong; Chen, Shuhui; Zhao, Guohong; Chen, Yijiao

    2010-09-01

    In this paper, we propose EGPS, an efficient privacy preserving scheme for vehicular ad hoc networks. The EGPS scheme is based on a very efficient group signature and Identity Based Cryptography(IBC) techniques. Several security properties of EGPS, including the correctness and unforgeability have been proved. Furthermore, EGPS is also proved to be more efficient than GSIS, which is currently one of the best state-of-the-art VANET privacy preserving schemes.

  12. Real Time Semantic Interoperability in AD HOC Networks of Geospatial Data Sources: Challenges, Achievements and Perspectives

    NASA Astrophysics Data System (ADS)

    Mostafavi, M. A.; Bakillah, M.

    2012-07-01

    Recent advances in geospatial technologies have made available large amount of geospatial data. Meanwhile, new developments in Internet and communication technologies created a shift from isolated geospatial databases to ad hoc networks of geospatial data sources, where data sources can join or leave the network, and form groups to share data and services. However, effective integration and sharing of geospatial data among these data sources and their users are hampered by semantic heterogeneities. These heterogeneities affect the spatial, temporal and thematic aspects of geospatial concepts. There have been many efforts to address semantic interoperability issues in the geospatial domain. These efforts were mainly focused on resolving heterogeneities caused by different and implicit representations of the concepts. However, many approaches have focused on the thematic aspects, leaving aside the explicit representation of spatial and temporal aspects. Also, most semantic interoperability approaches for networks have focused on automating the semantic mapping process. However, the ad hoc network structure is continuously modified by source addition or removal, formation of groups, etc. This dynamic aspect is often neglected in those approaches. This paper proposes a conceptual framework for real time semantic interoperability in ad hoc networks of geospatial data sources. The conceptual framework presents the fundamental elements of real time semantic interoperability through a hierarchy of interrelated semantic states and processes. Then, we use the conceptual framework to set the discussion on the achievements that have already been made, the challenges that remain to be addressed and perspectives with respect to these challenges.

  13. 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. PMID:16252818

  14. A Dirichlet reputation system in reliable routing of wireless ad hoc network

    SciTech Connect

    Yang, Dr. Li; Cui, Xiaohui; Cemerlic, Alma

    2010-01-01

    Ad hoc networks are very helpful in situations when no fixed network infrastructure is available, such as natural disasters and military conflicts. In such a network, all wireless nodes are equal peers simultaneously serving as both senders and routers for other nodes. Therefore, how to route packets through reliable paths becomes a fundamental problems when behaviors of certain nodes deviate from wireless ad hoc routing protocols. We proposed a novel Dirichlet reputation model based on Bayesian inference theory which evaluates reliability of each node in terms of packet delivery. Our system offers a way to predict and select a reliable path through combination of first-hand observation and second-hand reputation reports. We also proposed moving window mechanism which helps to adjust ours responsiveness of our system to changes of node behaviors. We integrated the Dirichlet reputation into routing protocol of wireless ad hoc networks. Our extensive simulation indicates that our proposed reputation system can improve good throughput of the network and reduce negative impacts caused by misbehaving nodes.

  15. Systematic lossy error protection for video transmission over wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoqing; Rane, Shantanu; Girod, Bernd

    2005-07-01

    Wireless ad hoc networks present a challenge for error-resilient video transmission, since node mobility and multipath fading result in time-varying link qualities in terms of packet loss ratio and available bandwidth. In this paper, we propose to use a systematic lossy error protection (SLEP) scheme for video transmission over wireless ad hoc networks. The transmitted video signal has two parts-a systematic portion consisting of a video sequence transmitted without channel coding over an error-prone channel, and error protection information consisting of a bitstream generated by Wyner-Ziv encoding of the video sequence. Using an end-to-end video distortion model in conjunction with online estimates of packet loss ratio and available bandwidth, the optimal Wyner-Ziv description can be selected dynamically according to current channel conditions. The scheme can also be applied to choose one path for transmission from amongst multiple candidate routes with varying available bandwidths and packet loss ratios, so that the expected end-to-end video distortion is maximized. Experimental results of video transmission over a simulated ad hoc wireless network shows that the proposed SLEP scheme outperforms the conventional application layer FEC approach in that it provides graceful degradation of received video quality over a wider range of packet loss ratios and is less susceptible to inaccuracy in the packet loss ratio estimation.

  16. Characterizing the Interaction Between Routing and MAC Protocols in Ad-Hoc Networks

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, A.; Marathe, M. V.

    2002-01-01

    We empirically study the effect of mobility on the performance of protocols designed for wireless ad-hoc networks. An important objective is to study the interaction of the Routing and MAC layer protocols under different mobility parameters. We use three basic mobility models: grid mobility model, random waypoint model, and exponential correlated random model. The performance of protocols is measured in terms of (i) latency, (ii) throughput, (iii) number of packets received, (iv) long term fairness and (v) number of control packets at the MAC and routing layer level. Three different commonly studied routing protocols are used: AODV, DSR and LAR1. Similarly three well known MAC protocols are used: MACA, 802.1 1 and CSMA. Our main contribution is simulation based experiments coupled with rigorous statistical analysis to characterize the interaction of MAC layer protocols with routing layer protocols in ad-hoc networks. From the results, we can conclude the following: e No single MAC or Routing protocol dominated the other protocols in their class. Probably more interestingly, no MAURouting protocol combination was better than other combinations over all scenarios and response variables. 0 In general, it is not meaningful to speak about a MAC or a routing protocol in isolation. Presence of interaction leads to trade-offs between the amount of control packets generated by each layer. The results raise the possibility of improving the performance of a particular MAC layer protocol by using a cleverly designed routing protocol or vice-versa. Thus in order to improve the performanceof a communication network, it is important to study the entire protocol stack as a single algorithmic construct; optimizing individual layers in the seven layer OS1 stack will not yield performance improvements beyond a point. A methodological contribution of this paper is the use of statistical methods such as analysis of variance (ANOVA), to characterize the interaction between the protocols

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

    PubMed

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

    2016-01-01

    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

  18. 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

  19. Further Development of Synchronous Array Method for Ad Hoc Wireless Networks

    NASA Astrophysics Data System (ADS)

    Yu, Yuan; Huang, Yi; Zhao, Bin; Hua, Yingbo

    2008-12-01

    A further development of the synchronous array method (SAM) as a medium access control scheme for large-scale ad hoc wireless networks is presented. Under SAM, all transmissions of data packets between adjacent nodes are synchronized on a frame-by-frame basis, and the spacing between concurrent cochannel transmissions of data packets is properly controlled. An opportunistic SAM (O-SAM) is presented which allows concurrent cochannel transmissions to be locally adaptive to channel gain variations. A distributed SAM (D-SAM) is discussed that schedules all concurrent cochannel transmissions in a distributed fashion. For networks of low mobility, the control overhead required by SAM can be made much smaller than the payload. By analysis and simulation, the intranetwork throughput of O-SAM and D-SAM is evaluated. The effects of traffic load and multiple antennas on the intranetwork throughput are studied. The throughput of ALOHA is also analyzed and compared with that of O-SAM and D-SAM. By a distance-weighted throughput, a comparison of long distance transmission versus short distance transmission is also presented. The study of D-SAM reveals an important insight into the MSH-DSCH protocol adopted in IEEE 802.16 standards.

  20. 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.

  1. Mean field game theoretic approach for security in mobile ad-hoc networks

    NASA Astrophysics Data System (ADS)

    Wang, Yanwei; Tang, Helen; Yu, F. Richard; Huang, Minyi

    2013-05-01

    Game theory can provide a useful tool to study the security problem in mobile ad hoc networks (MANETs). Most existing work on applying game theories to security only considers two players in the security game model: an attacker and a defender. While this assumption is valid for a network with centralized administration, it may not be realistic in MANETs, where centralized administration is not available. Consequently, each individual node in a MANET should be treated separately in the security game model. In this paper, using recent advances in mean field game theory, we propose a novel game theoretic approach for security in MANETs. Mean field game theory provides a powerful mathematical tool for problems with a large number of players. Since security defence mechanisms consume precious system resources (e.g., energy), the proposed scheme considers not only the security requirement of MANETs but also the system resources. In addition, each node only needs to know its own state information and the aggregate effect of the other nodes in the MANET. Therefore, the proposed scheme is a fully distributed scheme. Simulation results are presented to illustrate the effectiveness of the proposed scheme.

  2. 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.

  3. 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.

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

    SciTech Connect

    Kurt Derr; Milos Manic

    2013-11-01

    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 dispersion 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.

  5. 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. PMID:27441127

  6. 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.

  7. 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.

  8. 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.

  9. Joint Random Access and Power Control Game in Ad Hoc Networks with Noncooperative Users

    NASA Astrophysics Data System (ADS)

    Long, Chengnian; Guan, Xinping

    We consider a distributed joint random access and power control scheme for interference management in wireless ad hoc networks. To derive decentralized solutions that do not require any cooperation among the users, we formulate this problem as non-cooperative joint random access and power control game, in which each user minimizes its average transmission cost with a given rate constraint. Using supermodular game theory, the existence and uniqueness of Nash equilibrium are established. Furthermore, we present an asynchronous distributed algorithm to compute the solution of the game based on myopic best response updates, which converges to Nash equilibrium globally.

  10. 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.

  11. 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

  12. 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

  13. 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

  14. Opportunistic Hybrid Transport Protocol (OHTP) for Cognitive Radio Ad Hoc Sensor Networks.

    PubMed

    Bin Zikria, Yousaf; Nosheen, Summera; Ishmanov, Farruh; Kim, Sung Won

    2015-01-01

    The inefficient assignment of spectrum for different communications purposes, plus technology enhancements and ever-increasing usage of wireless technology is causing spectrum scarcity. To address this issue, one of the proposed solutions in the literature is to access the spectrum dynamically or opportunistically. Therefore, the concept of cognitive radio appeared, which opens up a new research paradigm. There is extensive research on the physical, medium access control and network layers. The impact of the transport layer on the performance of cognitive radio ad hoc sensor networks is still unknown/unexplored. The Internet's de facto transport protocol is not well suited to wireless networks because of its congestion control mechanism. We propose an opportunistic hybrid transport protocol for cognitive radio ad hoc sensor networks. We developed a new congestion control mechanism to differentiate true congestion from interruption loss. After such detection and differentiation, we propose methods to handle them opportunistically. There are several benefits to window- and rate-based protocols. To exploit the benefits of both in order to enhance overall system performance, we propose a hybrid transport protocol. We empirically calculate the optimal threshold value to switch between window- and rate-based mechanisms. We then compare our proposed transport protocol to Transmission Control Protocol (TCP)-friendly rate control, TCP-friendly rate control for cognitive radio, and TCP-friendly window-based control. We ran an extensive set of simulations in Network Simulator 2. The results indicate that the proposed transport protocol performs better than all the others. PMID:26694396

  15. 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. PMID:25258736

  16. 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

  17. 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. PMID:23766725

  18. 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

  19. New efficiency algorithm for flooding the packet in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Lee, Kyuhwan; Ma, Joongsoo

    2002-08-01

    This paper proposes a novel flooding algorithm based on an existing IEEE 802.11 MAC protocol in wireless ad hoc networks. Currently when we use the multi-hop routing algorithm, such as the Ad hoc On-demand Distance Vector (AODV) algorithm, the Cluster-Based Routing Protocol (CBRP) and so on, we frequently use the broadcast packet in order to get the topology information. At this time all nodes receiving the packet try to forward the received packet to other nodes. If a number of nodes are located in the sender's coverage, the channel is busy due to the delivery of the received packet. With respect to the coverage of the IEEE 802.11, the utilization factor of the wireless network is decreased because of occupying the channel to distribute the received packet. Thus we propose the new algorithm to resolve this problem. In this algorithm, each node maintains a table of immediate neighbors as well as each neighbor's neighbors. When each node receiving broadcast packets in the sender's coverage forwards the packets, it decides whether to forward them or not by comparing the neighbor list of receiver with that of sender. The proposed algorithm can increase the network efficiency due to the decrease in frequency of broadcast packets in the multi-hop routing protocol. Finally, we evaluate the improved performance through the simulation.

  20. 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. PMID:25136697

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    Ding, Jin; Medidi, Sirisha R.

    2004-08-01

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

  3. 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.

  4. 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

  5. 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.

  6. Enhancing the Social Capital of Learning Communities by Using an Ad Hoc Transient Communities Service

    NASA Astrophysics Data System (ADS)

    Fetter, Sibren; Berlanga, Adriana J.; Sloep, Peter

    In online learning, communities can help to enhance learning. However, because of the dynamic nature of communities, attaining and sustaining these communities can be difficult. One aspect that has an influence on, and is influenced by these dynamics is the social capital of a community. Features of social capital are the social network structure, the sense of belonging and, the support received and provided. It is hypothesized that these features can be improved by using Ad Hoc Transient Communities (AHTCs). Through an AHTC learners are brought together for a specific, learning-related goal (‘ad hoc’) and for only a limited amount of time (‘transience’). To test whether the use of AHTCs has a positive influence on the social capital, a learner support service which enables the use of AHTCs is proposed. Furthermore, requirements, prerequisites, and future research are discussed.

  7. Standardization of positive controls in diagnostic immunohistochemistry: recommendations from the International Ad Hoc Expert Committee.

    PubMed

    Torlakovic, Emina E; Nielsen, Søren; Francis, Glenn; Garratt, John; Gilks, Blake; Goldsmith, Jeffrey D; Hornick, Jason L; Hyjek, Elizabeth; Ibrahim, Merdol; Miller, Keith; Petcu, Eugen; Swanson, Paul E; Zhou, Xiaoge; Taylor, Clive R; Vyberg, Mogens

    2015-01-01

    Diagnostic immunohistochemistry (dIHC) has been practiced for several decades, with an ongoing expansion of applications for diagnostic use, and more recently for detection of prognostic and predictive biomarkers. However, standardization of practice has yet to be achieved, despite significant advances in methodology. An Ad Hoc Expert Committee was formed to address the standardization of controls, which is a missing link in demonstrating and assuring standardization of the various components of dIHC. This committee has also developed a concept of immunohistochemistry critical assay performance controls that are intended to facilitate methodology transfer and harmonization in dIHC. Furthermore, the committee has clarified definitions of IHC assay sensitivity and specificity, with special emphasis on how these definitions apply to positive controls. Recommendations for "best laboratory practice" regarding positive controls for dIHC are specified. The first set of immunohistochemistry critical assay performance controls for several frequently used IHC stains or tests is also developed and presented. PMID:25474126

  8. 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.

  9. Topology Control in Large-Scale High Dynamic Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    El-Habbal, Mohamed; Rückert, Ulrich; Witkowski, Ulf

    We present our contribution in projects related to ad-hoc networking using different routing protocols and hardware platforms, showing our results and new solutions regarding topology control and routing protocols. We mainly focus on our work in the GUARDIANS EU-project, where as a main disaster scenario a large industrial warehouse on fire is assumed. The paper presents the simulation results for the routing protocols ACR, DSR and EDSR, as well as the implementation of down-scaled demos for supporting the autonomous team of robots as well as the human squad team with robust communication coverage. Various hardware platforms were used in the demos for distance measurement, based on laser range finder and radio communication with time of flight analysis.

  10. 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

  11. Implementation and performance evaluation of mobile ad hoc network for Emergency Telemedicine System in disaster areas.

    PubMed

    Kim, J C; Kim, D Y; Jung, S M; Lee, M H; Kim, K S; Lee, C K; Nah, J Y; Lee, S H; Kim, J H; Choi, W J; Yoo, S K

    2009-01-01

    So far we have developed Emergency Telemedicine System (ETS) which is a robust system using heterogeneous networks. In disaster areas, however, ETS cannot be used if the primary network channel is disabled due to damages on the network infrastructures. Thus we designed network management software for disaster communication network by combination of Mobile Ad hoc Network (MANET) and Wireless LAN (WLAN). This software maintains routes to a Backbone Gateway Node in dynamic network topologies. In this paper, we introduce the proposed disaster communication network with management software, and evaluate its performance using ETS between Medical Center and simulated disaster areas. We also present the results of network performance analysis which identifies the possibility of actual Telemedicine Service in disaster areas via MANET and mobile network (e.g. HSDPA, WiBro). PMID:19964544

  12. Secure Adaptive Topology Control for Wireless Ad-Hoc Sensor Networks

    PubMed Central

    Hsueh, Ching-Tsung; Li, Yu-Wei; Wen, Chih-Yu; Ouyang, Yen-Chieh

    2010-01-01

    This paper presents a secure decentralized clustering algorithm for wireless ad-hoc sensor networks. The algorithm operates without a centralized controller, operates asynchronously, and does not require that the location of the sensors be known a priori. Based on the cluster-based topology, secure hierarchical communication protocols and dynamic quarantine strategies are introduced to defend against spam attacks, since this type of attacks can exhaust the energy of sensor nodes and will shorten the lifetime of a sensor network drastically. By adjusting the threshold of infected percentage of the cluster coverage, our scheme can dynamically coordinate the proportion of the quarantine region and adaptively achieve the cluster control and the neighborhood control of attacks. Simulation results show that the proposed approach is feasible and cost effective for wireless sensor networks. PMID:22205866

  13. 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

  14. Noise-assisted concurrent multipath traffic distribution in ad hoc networks.

    PubMed

    Asvarujanon, Narun; Leibnitz, Kenji; Wakamiya, Naoki; 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

  15. A Leasing Model to Deal with Partial Failures in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Gonzalez Boix, Elisa; van Cutsem, Tom; Vallejos, Jorge; de Meuter, Wolfgang; D'Hondt, Theo

    In mobile ad hoc networks (MANETs) many partial failures are the result of temporary network partitions due to the intermittent connectivity of mobile devices. Some of these failures will be permanent and require application-level failure handling. However, it is impossible to distinguish a permanent from a transient failure. Leasing provides a solution to this problem based on the temporal restriction of resources. But to date no leasing model has been designed specifically for MANETs. In this paper, we identify three characteristics required for a leasing model to be usable in a MANET, discuss the issues with existing leasing models and then propose the leased object references model, which integrates leasing with remote object references. In addition, we describe an implementation of the model in the programming language AmbientTalk. Leased object references provide an extensible framework that allows programmers to express their own leasing patterns and enables both lease holders (clients) and lease grantors (services) to deal with permanent failures.

  16. Analysis of a distributed algorithm to determine multiple routes with path diversity in ad hoc networks.

    SciTech Connect

    Ghosal, Dipak; Mueller, Stephen Ng

    2005-04-01

    With multipath routing in mobile ad hoc networks (MANETs), a source can establish multiple routes to a destination for routing data. In MANETs, mulitpath routing can be used to provide route resilience, smaller end-to-end delay, and better load balancing. However, when the multiple paths are close together, transmissions of different paths may interfere with each other, causing degradation in performance. Besides interference, the physical diversity of paths also improves fault tolerance. We present a purely distributed multipath protocol based on the AODV-Multipath (AODVM) protocol called AODVM with Path Diversity (AODVM/PD) that finds multiple paths with a desired degree of correlation between paths specified as an input parameter to the algorithm. We demonstrate through detailed simulation analysis that multiple paths with low degree of correlation determined by AODVM/PD provides both smaller end-to-end delay than AODVM in networks with low mobility and better route resilience in the presence of correlated node failures.

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

    PubMed

    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

  18. 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.

  19. CP-TDMA: Coloring-and Probability-Based TDMA Scheduling for Wireless Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Zhang, Xuedan; Hong, Jun; Zhang, Lin; Shan, Xiuming; Li, Victor O. K.

    This paper addresses the issue of transmission scheduling in wireless ad hoc networks. We propose a Time Division Multiple Access (TDMA) scheduling scheme based on edge coloring and probabilistic assignment, called CP-TDMA. We categorize the conflicts suffered by wireless links into two types: explicit conflicts and implicit conflicts, and utilize two different strategies to deal with them. Explicit conflicts are avoided completely by a simple distributed edge-coloring algorithm μ-M, and implicit conflicts are minimized by applying probabilistic time slot assignments to links. We evaluate CP-TDMA analytically and numerically, and find that CP-TDMA, which requires only local information exhibits a better performance than previous work.

  20. Performance optimisation through EPT-WBC in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Agarwal, Ratish; Gupta, Roopam; Motwani, Mahesh

    2016-03-01

    Mobile ad hoc networks are self-organised, infrastructure-less networks in which each mobile host works as a router to provide connectivity within the network. Nodes out of reach to each other can communicate with the help of intermediate routers (nodes). Routing protocols are the rules which determine the way in which these routing activities are to be performed. In cluster-based architecture, some selected nodes (clusterheads) are identified to bear the extra burden of network activities like routing. Selection of clusterheads is a critical issue which significantly affects the performance of the network. This paper proposes an enhanced performance and trusted weight-based clustering approach in which a number of performance factors such as trust, load balancing, energy consumption, mobility and battery power are considered for the selection of clusterheads. Moreover, the performance of the proposed scheme is compared with other existing approaches to demonstrate the effectiveness of the work.

  1. Performance Analysis of Ad Hoc Routing Protocols in City Scenario for VANET

    NASA Astrophysics Data System (ADS)

    Das, Sanjoy; Raw, Ram Shringar; Das, Indrani

    2011-12-01

    In this paper, performance analysis of Location Aided Routing (LAR), AODV and DSR protocol in city scenarios has been done. The mobility model considered is Manhattan model. This mobility model used to emulate the movement pattern of nodes i.e., vehicles on streets defined by maps. Our objective is to provide a comparative analysis among LAR, AODV and DSR protocol in city scenarios in Vehicular Ad hoc Networks. The simulation work has been conducted using the Glomosim 2.03 simulator. The results show that LAR1 protocol achieves maximum packet delivery ratio is 100% in the sparsely populated network. The delay is maximum in AODV 121.88 ms when the number of node is 10 in the network. The results show that LAR1 outperform DSR and AODV in term of packet delivery ratio and end to end delay.

  2. Opportunistic Hybrid Transport Protocol (OHTP) for Cognitive Radio Ad Hoc Sensor Networks

    PubMed Central

    Zikria, Yousaf Bin; Nosheen, Summera; Ishmanov, Farruh; Kim, Sung Won

    2015-01-01

    The inefficient assignment of spectrum for different communications purposes, plus technology enhancements and ever-increasing usage of wireless technology is causing spectrum scarcity. To address this issue, one of the proposed solutions in the literature is to access the spectrum dynamically or opportunistically. Therefore, the concept of cognitive radio appeared, which opens up a new research paradigm. There is extensive research on the physical, medium access control and network layers. The impact of the transport layer on the performance of cognitive radio ad hoc sensor networks is still unknown/unexplored. The Internet’s de facto transport protocol is not well suited to wireless networks because of its congestion control mechanism. We propose an opportunistic hybrid transport protocol for cognitive radio ad hoc sensor networks. We developed a new congestion control mechanism to differentiate true congestion from interruption loss. After such detection and differentiation, we propose methods to handle them opportunistically. There are several benefits to window- and rate-based protocols. To exploit the benefits of both in order to enhance overall system performance, we propose a hybrid transport protocol. We empirically calculate the optimal threshold value to switch between window- and rate-based mechanisms. We then compare our proposed transport protocol to Transmission Control Protocol (TCP)-friendly rate control, TCP-friendly rate control for cognitive radio, and TCP-friendly window-based control. We ran an extensive set of simulations in Network Simulator 2. The results indicate that the proposed transport protocol performs better than all the others. PMID:26694396

  3. Exploiting Location Information and Enabling Adaptive Mobile Ad Hoc Network Protocols

    NASA Astrophysics Data System (ADS)

    Boleng, Jeff

    2002-09-01

    Mobile Ad Hoc Networks (MANETs) consist of a group of mobile nodes which form a communication network without prior infrastructure. Each node in the network is responsible to provide services to other nodes in order to realize the ad hoc communication capability. A key component and primary challenge in MANETs is routing data packets over multiple hops between nodes. MANET routing has received considerable research interest recently. However, no routing protocol proposed to date has proven to be effective in the wide range of mobility conditions present in a MANET. We combine location information and mobility feedback to create an innovative MANET routing protocol which we prove is effective over a wide range of mobility conditions typical in a MANET. We introduce link duration as our mobility feedback metric, and we demonstrate that mobility feedback using link duration effectively enables adaptive MANET protocols. Using our mobility feedback agent, we develop a hybrid MANET routing protocol which adapts in order to combine the strengths of both component protocols while avoiding their weaknesses. Our hybrid, adaptive protocol achieves data packet delivery ratios above 80% in highly demanding network mobility conditions (i.e. link durations less than 4 seconds and node speeds up to 40 m/s). No existing MANET routing protocol can achieve such high performance operating alone. In addition we show that location information increases the performance of MANET routing. Finally, we develop a comprehensive set of mathematical models for data packet delivery ratio, overhead, and delay. These models confirm the suitability of link duration as a mobility metric, validate our simulation results and conclusions, and provide valuable insight into reactive MANET routing protocol operation.

  4. 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.

  5. Evaluating the Importance of Image-related Text for Ad-hoc and Case-based Biomedical Article Retrieval

    PubMed Central

    Simpson, Matthew S.; Demner-Fushman, Dina; Thoma, George R.

    2010-01-01

    Images and their associated text are an essential source of information in biomedical articles. However, their use in providing evidence for clinical case descriptions has yet to be evaluated in the context of information retrieval. Given the complexity of case-based document retrieval, understanding the importance of images and image-related text is critical for future research into text- and content-based approaches to this problem. In this study, we compare the extent to which image-related text is useful in facilitating document retrieval for both case-based information requests and ad-hoc clinical questions in the domain of family practice. We show that case-based document retrieval is significantly improved with the use of image-related text whereas retrieval for clinical questions is largely unaffected. This suggests that visual evidence is more relevant for the case descriptions used in our study than the clinical questions. PMID:21347079

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

    DOE PAGESBeta

    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

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

    SciTech Connect

    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 the 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 application

  8. Future Information Services at the Texas A&M University Library: Background and Recommendations (Report of an Ad Hoc Committee).

    ERIC Educational Resources Information Center

    Cook, Colleen; And Others

    The Ad Hoc Committee on Future Information Services explored possible future directions for information services at Texas A&M University Library and developed a plan to guide the library into the next decade in terms of automated access to information. In exploring future directions for automated information services, the committee members…

  9. 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…

  10. 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.

  11. 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

  12. 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.

  13. 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. PMID:26696419

  14. Multiobjective Reinforcement Learning for Traffic Signal Control Using Vehicular Ad Hoc Network

    NASA Astrophysics Data System (ADS)

    Houli, Duan; Zhiheng, Li; Yi, Zhang

    2010-12-01

    We propose a new multiobjective control algorithm based on reinforcement learning for urban traffic signal control, named multi-RL. A multiagent structure is used to describe the traffic system. A vehicular ad hoc network is used for the data exchange among agents. A reinforcement learning algorithm is applied to predict the overall value of the optimization objective given vehicles' states. The policy which minimizes the cumulative value of the optimization objective is regarded as the optimal one. In order to make the method adaptive to various traffic conditions, we also introduce a multiobjective control scheme in which the optimization objective is selected adaptively to real-time traffic states. The optimization objectives include the vehicle stops, the average waiting time, and the maximum queue length of the next intersection. In addition, we also accommodate a priority control to the buses and the emergency vehicles through our model. The simulation results indicated that our algorithm could perform more efficiently than traditional traffic light control methods.

  15. 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

  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

    2014-01-01

    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

  17. 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

  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. A Threshold-Adaptive Reputation System on Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Tsai, Hsiao-Chien; Lo, Nai-Wei; Wu, Tzong-Chen

    In recent years huge potential benefits from novel applications in mobile ad hoc networks (MANET) have been discussed extensively. However, without robust security mechanisms and systems to provide safety shell through the MANET infrastructure, MANET applications can be vulnerable and hammered by malicious attackers easily. In order to detect misbehaved message routing and identify malicious attackers in MANET, schemes based on reputation concept have shown their advantages in this area in terms of good scalability and simple threshold-based detection strategy. We observed that previous reputation schemes generally use predefined thresholds which do not take into account the effect of behavior dynamics between nodes in a period of time. In this paper, we propose a Threshold-Adaptive Reputation System (TARS) to overcome the shortcomings of static threshold strategy and improve the overall MANET performance under misbehaved routing attack. A fuzzy-based inference engine is introduced to evaluate the trustiness of a node's one-hop neighbors. Malicious nodes whose trust values are lower than the adaptive threshold, will be detected and filtered out by their honest neighbors during trustiness evaluation process. The results of network simulation show that the TARS outperforms other compared schemes under security attacks in most cases and at the same time reduces the decrease of total packet delivery ratio by 67% in comparison with MANET without reputation system.

  20. 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

  1. 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.

  2. 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.

  3. A Sensitive Secondary Users Selection Algorithm for Cognitive Radio Ad Hoc Networks

    PubMed Central

    Li, Aohan; Han, Guangjie; Wan, Liangtian; Shu, Lei

    2016-01-01

    Secondary Users (SUs) are allowed to use the temporarily unused licensed spectrum without disturbing Primary Users (PUs) in Cognitive Radio Ad Hoc Networks (CRAHNs). Existing architectures for CRAHNs impose energy-consuming Cognitive Radios (CRs) on SUs. However, the advanced CRs will increase energy cost for their cognitive functionalities, which is undesirable for the battery powered devices. A new architecture referred to as spectral Requirement-based CRAHN (RCRAHN) is proposed to enhance energy efficiency for CRAHNs in this paper. In RCRAHNs, only parts of SUs are equipped with CRs. SUs equipped with CRs are referred to as Cognitive Radio Users (CRUs). To further enhance energy efficiency of CRAHNs, we aim to select minimum CRUs to sense available spectrum. A non-linear programming problem is mathematically formulated under the constraints of energy efficiency and real-time. Considering the NP-hardness of the problem, a framework of a heuristic algorithm referred to as Sensitive Secondary Users Selection (SSUS) was designed to compute the near-optimal solutions. The simulation results demonstrate that SSUS not only improves the energy efficiency, but also achieves satisfied performances in end-to-end delay and communication reliability. PMID:27023562

  4. Energy-Efficient Algorithm for Broadcasting in Ad Hoc Wireless Sensor Networks

    PubMed Central

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

    2013-01-01

    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. PMID:23584121

  5. Ad Hoc Query Support For Very Large Simulation Mesh Data: The Metadata Approach

    SciTech Connect

    Lee, B; Snapp, R; Musick, R; Critchlow, T

    2001-12-17

    We present our approach to enabling approximate ad hoc queries on terabyte-scale mesh data generated from large scientific simulations through the extension and integration of database, statistical, and data mining techniques. There are several significant barriers to overcome in achieving this objective. First, large-scale simulation data is already at the multi-terabyte scale and growing quickly, thus rendering traditional forms of interactive data exploration and query processing untenable. Second, a priori knowledge of user queries is not available, making it impossible to tune special-purpose solutions. Third, the data has spatial and temporal aspects, as well as arbitrarily high dimensionality, which exacerbates the task of finding compact, accurate, and easy-to-compute data models. Our approach is to preprocess the mesh data to generate highly compressed, lossy models that are used in lieu of the original data to answer users' queries. This approach leads to interesting challenges. The model (equivalently, the content-oriented metadata) being generated must be smaller than the original data by at least an order of magnitude. Second, the metadata representation must contain enough information to support a broad class of queries. Finally, the accuracy and speed of the queries must be within the tolerances required by users. In this paper we give an overview of ongoing development efforts with an emphasis on extracting metadata and using it in query processing.

  6. 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

  7. A Sensitive Secondary Users Selection Algorithm for Cognitive Radio Ad Hoc Networks.

    PubMed

    Li, Aohan; Han, Guangjie; Wan, Liangtian; Shu, Lei

    2016-01-01

    Secondary Users (SUs) are allowed to use the temporarily unused licensed spectrum without disturbing Primary Users (PUs) in Cognitive Radio Ad Hoc Networks (CRAHNs). Existing architectures for CRAHNs impose energy-consuming Cognitive Radios (CRs) on SUs. However, the advanced CRs will increase energy cost for their cognitive functionalities, which is undesirable for the battery powered devices. A new architecture referred to as spectral Requirement-based CRAHN (RCRAHN) is proposed to enhance energy efficiency for CRAHNs in this paper. In RCRAHNs, only parts of SUs are equipped with CRs. SUs equipped with CRs are referred to as Cognitive Radio Users (CRUs). To further enhance energy efficiency of CRAHNs, we aim to select minimum CRUs to sense available spectrum. A non-linear programming problem is mathematically formulated under the constraints of energy efficiency and real-time. Considering the NP-hardness of the problem, a framework of a heuristic algorithm referred to as Sensitive Secondary Users Selection (SSUS) was designed to compute the near-optimal solutions. The simulation results demonstrate that SSUS not only improves the energy efficiency, but also achieves satisfied performances in end-to-end delay and communication reliability. PMID:27023562

  8. 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

    2016-01-01

    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

  9. 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.

  10. 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.

  11. 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. PMID:25946001

  12. Enhanced ad hoc wireless connectivity in complex environment using small radio repeater systems

    NASA Astrophysics Data System (ADS)

    Sarabandi, Kamal; Song, Young Jun; Oh, Jungsuek

    2011-06-01

    Ad hoc communication among small robotic platforms in complex indoor environment is further challenged by three limiting factors: 1) limited power, 2) small size antennas, and 3) near-ground operation. In complex environments such as indoor scenarios often times the line-of-sight communication cannot be established and the wireless connectivity must rely on multi-path propagation. As a result, the propagation path-loss is much higher than free-space, and more power will be needed to obtain the need coverage. Near ground operation also leads to increased path-loss. To maintain the network connectivity without increasing the required power a novel high gain miniaturized radio repeater is presented. Unlike existing repeater systems, this system utilizes two closely spaced low profile miniaturized planar antennas capable of producing omnidirectional and vertical radiation patterns as well as a channel isolator layer that serves to decouple the adjacent antennas. The meta-material based channel isolator serves as an electromagnetic shield, thus enabling it to be built in a sub-wavelength size of 0.07λ0 2 × λ0/70, the smallest repeater ever built. Also wave propagation simulations have been conducted to determine the required gain of such repeaters so to ensure the signal from the repeater is the dominant component. A prototype of the small radio repeater is fabricated to verify the design performance through a standard free-space measurement setup.

  13. 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.

  14. 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.

  15. 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

  16. Bringing Ad-Hoc Analytics to Big Earth Data: the EarthServer Experience

    NASA Astrophysics Data System (ADS)

    Baumann, Peter

    2014-05-01

    From the commonly accepted Vs defining the Big Data challenge - volume, velocity, variety - we more and more learn that the sheer volume is not the only, and often not even the decisive factor inhibiting access and analytics. In particular variety of data is a frequent core issue, posing manifold issues. Based on this observation we claim that a key aspect to analytics is the freedom to ask any questions, simple or complex, anytime and combining any choice of data structures, whatever diverging they may be. Actually, techniques for such "ad-hoc queries" we can learn from classical databases. Their concept of high-level query languages brings along several benefits: a uniform semantic, allowing machine-to-machine communication, including automatic generation of queries; massive server-side optimization and parallelization; and building attractive client interfaces hiding the query syntax from casual users while allowing power users to utilize it. However, these benefits used to be available only on tabular and set oriented data, text, and - more recently - graph data. With the advent of Array Databases, they become available on large multidimensional raster data assets as well, getting one step closer to the Holy Grail of itnegrated, uniform retrieval for users. ErthServer is a transatlantic initiative setting up operationa linfrastructures based on this paradigm. In our talk, we present core EarthServer technology concepts as well as a spectrum of Earth Science applications utilizing the EarthServer platform for versatile, visualisation supported analytics services. Further, we discuss the substantial impact EarthServer is having on Big Geo Data standardization in OGC and ISO. Time and Internet connection permitting a live demo can be presented.

  17. 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

  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. PMID:26636576

  19. 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.

  20. 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

  1. 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. PMID:26384813

  2. FRCA: a fuzzy relevance-based cluster head selection algorithm for wireless mobile ad-hoc sensor networks.

    PubMed

    Lee, Chongdeuk; Jeong, Taegwon

    2011-01-01

    Clustering is an important mechanism that efficiently provides information for mobile nodes and improves the processing capacity of routing, bandwidth allocation, and resource management and sharing. Clustering algorithms can be based on such criteria as the battery power of nodes, mobility, network size, distance, speed and direction. Above all, in order to achieve good clustering performance, overhead should be minimized, allowing mobile nodes to join and leave without perturbing the membership of the cluster while preserving current cluster structure as much as possible. This paper proposes a Fuzzy Relevance-based Cluster head selection Algorithm (FRCA) to solve problems found in existing wireless mobile ad hoc sensor networks, such as the node distribution found in dynamic properties due to mobility and flat structures and disturbance of the cluster formation. The proposed mechanism uses fuzzy relevance to select the cluster head for clustering in wireless mobile ad hoc sensor networks. In the simulation implemented on the NS-2 simulator, the proposed FRCA is compared with algorithms such as the Cluster-based Routing Protocol (CBRP), the Weighted-based Adaptive Clustering Algorithm (WACA), and the Scenario-based Clustering Algorithm for Mobile ad hoc networks (SCAM). The simulation results showed that the proposed FRCA achieves better performance than that of the other existing mechanisms. PMID:22163905

  3. 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

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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.

  9. A Novel Clustering Algorithm for Mobile Ad Hoc Networks Based on Determination of Virtual Links' Weight to Increase Network Stability

    PubMed Central

    Karimi, Abbas; Afsharfarnia, Abbas; Zarafshan, Faraneh; Al-Haddad, S. A. R.

    2014-01-01

    The stability of clusters is a serious issue in mobile ad hoc networks. Low stability of clusters may lead to rapid failure of clusters, high energy consumption for reclustering, and decrease in the overall network stability in mobile ad hoc network. In order to improve the stability of clusters, weight-based clustering algorithms are utilized. However, these algorithms only use limited features of the nodes. Thus, they decrease the weight accuracy in determining node's competency and lead to incorrect selection of cluster heads. A new weight-based algorithm presented in this paper not only determines node's weight using its own features, but also considers the direct effect of feature of adjacent nodes. It determines the weight of virtual links between nodes and the effect of the weights on determining node's final weight. By using this strategy, the highest weight is assigned to the best choices for being the cluster heads and the accuracy of nodes selection increases. The performance of new algorithm is analyzed by using computer simulation. The results show that produced clusters have longer lifetime and higher stability. Mathematical simulation shows that this algorithm has high availability in case of failure. PMID:25114965

  10. Combined bio-inspired/evolutionary computational methods in cross-layer protocol optimization for wireless ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2011-06-01

    Published studies have focused on the application of one bio-inspired or evolutionary computational method to the functions of a single protocol layer in a wireless ad hoc sensor network (WSN). For example, swarm intelligence in the form of ant colony optimization (ACO), has been repeatedly considered for the routing of data/information among nodes, a network-layer function, while genetic algorithms (GAs) have been used to select transmission frequencies and power levels, physical-layer functions. Similarly, artificial immune systems (AISs) as well as trust models of quantized data reputation have been invoked for detection of network intrusions that cause anomalies in data and information; these act on the application and presentation layers. Most recently, a self-organizing scheduling scheme inspired by frog-calling behavior for reliable data transmission in wireless sensor networks, termed anti-phase synchronization, has been applied to realize collision-free transmissions between neighboring nodes, a function of the MAC layer. In a novel departure from previous work, the cross-layer approach to WSN protocol design suggests applying more than one evolutionary computational method to the functions of the appropriate layers to improve the QoS performance of the cross-layer design beyond that of one method applied to a single layer's functions. A baseline WSN protocol design, embedding GAs, anti-phase synchronization, ACO, and a trust model based on quantized data reputation at the physical, MAC, network, and application layers, respectively, is constructed. Simulation results demonstrate the synergies among the bioinspired/ evolutionary methods of the proposed baseline design improve the overall QoS performance of networks over that of a single computational method.

  11. Scope of practice in speech-language pathology. Ad Hoc Committee on Scope of Practice in Speech-Language Pathology.

    PubMed

    1996-01-01

    This scope of practice in speech-language pathology statement is an official policy of the American Speech-Language-Hearing Association (ASHA). It was developed by the Ad Hoc Committee on Scope of Practice in Speech-Language Pathology: Sarah W. Blackstone, chair; Diane Paul-Brown, ex officio; David A. Brandt; Rhonda Friedlander; Luis F. Riquelme; and Mark Ylvisaker. Crystal S. Cooper, vice president for professional practices in speech-language pathology, served as monitoring vice-president. The contributions of the editor, Jude Langsam, and select the widespread peer reviewers are grateful acknowledged. This statement supersedes the Scope of Practice, Speech-Language Pathology and Audiology statement (LC 6-89), Asha, April 1990, 1-2. PMID:8680261

  12. Determination of endogenous concentration of γ-hydroxybutyric acid (GHB) in hair through an ad hoc GC-MS analysis: A study on a wide population and influence of gender and age.

    PubMed

    Vaiano, Fabio; Serpelloni, Giovanni; Furlanetto, Sandra; Palumbo, Diego; Mari, Francesco; Fioravanti, Alessia; Bertol, Elisabetta

    2016-01-25

    γ-Hydroxybutyric acid (GHB) spread for recreational purposes or as "rape drug" represents a hard issue for forensic toxicologists due to its endogenous nature. It is clear that an actual and reliable discrimination between basal and exogenous levels is mandatory to achieve a correct evaluation of conscious/unconscious administration. This research aimed to study the GHB baseline in hair samples, collected from 150 volunteers, non-consumers of any drugs of abuse, in order to evaluate if a generic cut-off value could be accepted, also focusing on potential influences of gender and age. The analysis consisted of an overnight incubation with NaOH at 56 °C, liquid-liquid extraction with ethylacetate and trimethylsylil derivatization. Detection was carried out through gas chromatography-mass spectrometry in single ion monitoring (m/z 233, 234, 147 for GHB; m/z 239, 240 and 147 for GHB-d6). The endogenous amount in "blank" hair was estimated by the standard addition method. Concentration range was 0.279-2.839 ng/mg. In males, the average GHB levels were higher than in females (0.829 vs 0.596 ng/mg, respectively), especially in the first age category (<30 years, 1.008 vs 0.606 ng/mg, respectively). Age influences on GHB levels seemed to be different among the two sexes: in male population concentrations were higher <30 (1.008 ng/mg) and similar in the other age ranges (0.762 ng/mg, 30-50; 0.763 ng/mg, >50); in female, quite similar levels were registered throughout all the age categories (0.606 ng/mg, <30; 0.536 ng/mg, 30-50; 0.691 ng/mg, >50). Further study should be performed on GHB physiology in order to better understand these differences among ages and genders. Moreover, we demonstrated that for hair analysis a cut-off reference value is not strictly mandatory, underlining the great interpretative valence of segmental analysis. PMID:26551534

  13. Potentials, Limitations and Applications of long-term and mobile ad-hoc Wireless Sensor Networks for Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Bumberger, Jan; Mollenhauer, Hannes; Lapteva, Yulia; Hutschenreuther, Tino; Toepfer, Hannes; Dietrich, Peter

    2014-05-01

    To characterize environmental systems it is necessary to identify and describe processes with suitable methods. Environmental systems are often characterized by their high heterogeneity, so individual measurements for their complete representation are often not sufficient. The application of wireless sensor networks in terrestrial and aquatic ecosystems offer significant benefits as a better consideration of the local test conditions becomes possible. This can be essential for the monitoring of heterogeneous environmental systems. Significant advantages in the application of mobile ad-hoc wireless sensor networks are their self-organizing behavior, resulting in a major reduction in installation and operation costs and time. In addition, a point measurement with a sensor is significantly improved by measuring at several points. It is also possible to perform analog and digital signal processing and computation on the basis of the measured data close to the sensor. Hence, a significant reduction of the data to be transmitted can be achieved which leads to a better energy management of sensor nodes. Furthermore, their localization via satellite, the miniaturization of the nodes and long-term energy self-sufficiency are current topics under investigation. The possibilities and limitations of the applicability of wireless sensor networks for long-term and mobile environmental monitoring are presented. A concepts and realization example are given in the field of micrometeorology and soil parameters for the interaction of biotic and abiotic processes .This long term monitoring is part of the Global Change Experimental Facility (GCEF), a large field-based experimental platform to assess the effects of climate change on ecosystem functions and processes under different land-use scenarios. Furthermore a mobile ad-hoc sensor network is presented for the monitoring of water induced mass wasting processes.

  14. Augmenting 3d City Model Components by Geodata Joins to Facilitate Ad-Hoc Geometric-Topologically Sound Integration

    NASA Astrophysics Data System (ADS)

    Kaden, R.; Kolbe, T. H.

    2012-07-01

    Virtual 3D city models are integrated complex compositions of spatial data of different themes, origin, quality, scale, and dimensions. Within this paper, we address the problem of spatial compatibility of geodata aiming to provide support for ad-hoc integration of virtual 3D city models including geodata of different sources and themes like buildings, terrain, and city furniture. In contrast to related work which is dealing with the integration of redundant geodata structured according to different data models and ontologies, we focus on the integration of complex 3D models of the same representation (here: CityGML) but regarding to the geometric-topological consistent matching of non-homologous objects, e.g. a building is connected to a road, and their geometric homogenisation. Therefore, we present an approach including a data model for a Geodata Join and the general concept of an integration procedure using the join information. The Geodata Join aims to bridge the lack of information between fragmented geodata by describing the relationship between adjacent objects from different datasets. The join information includes the geometrical representation of those parts of an object, which have a specific/known topological or geometrical relationship to another object. This part is referred to as a Connector and is either described by points, lines, or surfaces of the existing object geometry or by additional join geometry. In addition, the join information includes the specification of the connected object in the other dataset and the description of the topological and geometrical relationship between both objects, which is used to aid the matching process. Furthermore, the Geodata Join contains object-related information like accuracy values and restrictions of movement and deformation which are used to optimize the integration process. Based on these parameters, a functional model including a matching algorithm, transformation methods, and conditioned adjustment

  15. A Time-Slotted On-Demand Routing Protocol for Mobile Ad Hoc Unmanned Vehicle Systems

    SciTech Connect

    Hope Forsmann; Robert Hiromoto; John Svoboda

    2007-04-01

    The popularity of UAVs has increased dramatically because of their successful deployment in military operations, their ability to preserve human life, and the continual improvements in wireless communication that serves to increase their capabilities. We believe the usefulness of UAVs would be dramatically increased if formation flight were added to the list of capabilities. Currently, sustained formation flight with a cluster of UAVs has only been achieved with two nodes by the Multi-UAV Testbed at the Massachusetts Institute of Technology. (Park, 2004) Formation flight is a complex operation requiring the ability to adjust the flight patterns on the fly and correct for wind gusts, terrain, and differences in node equipment. All of which increases the amount of inner node communication. Since one of the problems with MANET communication is network congestion, we believe a first step towards formation flight can be made through improved inner node communication. We have investigated current communication routing protocols and developed an altered hybrid routing protocol in order to provide communication with less network congestion.

  16. 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

  17. 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…

  18. The Future of 12th Grade NAEP: Report of the Ad Hoc Committee on Planning for NAEP 12th Grade Assessments in 2009

    ERIC Educational Resources Information Center

    National Assessment Governing Board, 2006

    2006-01-01

    The task of the Ad Hoc Committee on Planning for the the National Assessment of Educational Progress (NAEP) 12th Grade Assessments in 2009 addresses three policy areas: (1) Conducting assessment at the state level in 12th grade; (2) Reporting on 12th grade student preparedness for college-credit coursework, training for employment and entrance…

  19. Scientific and Technical Information for Developing Countries. A Report of an Ad Hoc Advisory Panel of the Board on Science and Technology for International Development.

    ERIC Educational Resources Information Center

    National Academy of Sciences - National Research Council, Washington, DC.

    This report from an ad hoc advisory panel of the Board of Science and Technology for International Development attempts to provide an argument for the importance of systematic scientific and technical information transfer within the framework of the total technical assistance effort. It stresses the need for substantially greater activity and a…

  20. Priorities in Community Services Research for the Northeast: A Report of the Ad Hoc Committee on Community Services. Publication No. 10.

    ERIC Educational Resources Information Center

    Northeast Regional Center for Rural Development, Ithaca, NY.

    Constituted to include research users, the ad hoc Committee on Community Services Research in the Northeast analyzed the problems and information needs of community service personnel during a conference session. Issues and questions derived from this initial interchange were categorized and then translated into research problems. Criteria employed…

  1. On the Connectivity, Lifetime and Hop Count of Routes Determined Using the City Section and Manhattan Mobility Models for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Meghanathan, Natarajan

    The high-level contribution of this paper is a simulation based analysis of the network connectivity, hop count and lifetime of the routes determined for vehicular ad hoc networks (VANETs) using the City Section and Manhattan mobility models. The Random Waypoint mobility model is used as a benchmark in the simulation studies. Two kinds of paths are determined on the sequence of static graphs representing the topology over the duration of the network session: paths with the minimum hop count (using the Dijkstra algorithm) and stable paths with the longest lifetime (using our recently proposed OptPathTrans algorithm). Simulation results indicate that the City Section model provided higher network connectivity compared to the Manhattan model for all the network scenarios. Minimum hop paths and stable paths determined under the Manhattan model have a smaller lifetime and larger hop count compared to those determined using the City Section and Random Waypoint mobility models.

  2. Report and Recommendation of the Ad Hoc Committee to Review the College Calendar.

    ERIC Educational Resources Information Center

    San Joaquin Delta Coll., Stockton, CA.

    A study was conducted at San Joaquin Delta College (SJDC) to determine whether its present calendar, based on the traditional semester system, should be abandoned in favor of either the quarter or the early semester calendars. The study involved: (1) contacting employers to determine the effect of a calendar change on student employment, (2)…

  3. 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

  4. 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

    2015-01-01

    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

  5. 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.

  6. SARA: a self-adaptive and resource-aware approach towards secure wireless ad hoc and sensor networks

    NASA Astrophysics Data System (ADS)

    Chigan, Chunxiao; Li, Leiyuan

    2005-05-01

    Providing security is essential for mission critical Wireless Ad Hoc and Sensor Networks (WAHSN) applications. Often a highly secure mechanism inevitably consumes a rather large amount of system resources, which in turn may unintentionally cause a Security Service Denial of Service (SSDoS) attack. This paper proposes a self-adaptive resource-aware (SARA) security provisioning approach for WAHSNs. For resource scarce WAHSNs, SARA strives to provide the optimal tradeoff between the sufficient security (which is reflected by the Security Index (SI)) and the acceptable network performance degradation (which is reflected by the Performance Index (PI)). With the support of the offline optimal secure protocol selection module and the online self-adaptive security control module, SARA is capable of employing different combinations of secure protocol sets to satisfy different security need at different condition for different applications. To determine the security index SI of a secure protocol set, a heuristic cross-layer security-service mapping mechanism is presented. Furthermore, we evaluate performance index PI of a secure protocol set via simulation followed by Analysis of Variance (ANOVA). Consequently, the proposed self-adaptive security provisioning based on both SI and PI achieves the maximum overall network security services and network performance services, without causing the SSDoS attack. Furthermore, this self-adaptive mechanism is capable of switching from one secure protocol set to another while keeping similar level of security and performance, it thus provides additional security by security service hopping.

  7. Services Oriented Architectures and Rapid Deployment of Ad-Hoc Health Surveillance Systems: Lessons from Katrina Relief Efforts

    PubMed Central

    Mirhaji, Parsa; Casscells, S. Ward; Srinivasan, Arunkumar; Kunapareddy, Narendra; Byrne, Sean; Richards, David; 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 [1]. 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 [2]. To address this need, 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) [3, 4]. The system was post-coordinated through the orchestration of Web Services such as information integration, natural language processing, UMLS terminology services, syndromic case finding, and online analytical processing (OLAP) [5]. Here we will report the use of Internet-based and distributed architectures in providing timely, novel, and customizable solutions just in time for unprecedented events such as natural disasters. PMID:17238405

  8. On interaction between MAC and transport layers for media streaming in 802.11 ad hoc networks

    NASA Astrophysics Data System (ADS)

    Nahm, Kitae; Helmy, Ahmed; Kuo, C.-C. Jay

    2004-10-01

    We examine the validity of TCP-friendliness and the utility of equation-based congestion control as a mean for the media streaming service in 802.11 multi-hop networks. Our investigation is motivated by the recent findings of the bandwidth-delay product of 802.11 multi-hop networks via intensive computer simulations. We show that TCP behavior in 802.11 multi-hop networks is generally inefficient and unstable because the standard TCP is too aggressive considering the low bandwidth-delay product of 802.11 networks. We introduce the concept of the `fractional window' mechanism (which resembles the stop-and-go protocol) for TCP, and show that the modified TCP is more stable and efficient while outperforming the legacy TCP in 802.11-based ad hoc networks. Finally, we show that many of the typical problems of TCP protocol (performance, network fairness, and TCP-friendliness) in 802.11 networks can be solved simply by increasing the bandwidth-delay product of 802.11 networks without any TCP modification. Based on this observation, we conclude that the assumption of the ideal steady-state TCP behavior is generally invalid in 802.11 multi-hop networking environment, and that congestion control based on TCP-friendly equation can hardly provide TCP-fair throughput and smoothness in 802.11 multi-hop networking environment.

  9. 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. PMID:26024791

  10. Extended Virtual Spring Mesh (EVSM): The Distributed Self-Organizing Mobile Ad Hoc Network for Area Exploration

    SciTech Connect

    Kurt Derr

    2011-12-01

    Mobile Ad hoc NETworks (MANETs) are distributed self-organizing networks that can change locations and configure themselves on the fly. This paper focuses on an algorithmic approach for the deployment of a MANET within an enclosed area, such as a building in a disaster scenario, which can provide a robust communication infrastructure for search and rescue operations. While a virtual spring mesh (VSM) algorithm provides scalable, self-organizing, and fault-tolerant capabilities required by aMANET, the VSM lacks the MANET's capabilities of deployment mechanisms for blanket coverage of an area and does not provide an obstacle avoidance mechanism. This paper presents a new technique, an extended VSM (EVSM) algorithm that provides the following novelties: (1) new control laws for exploration and expansion to provide blanket coverage, (2) virtual adaptive springs enabling the mesh to expand as necessary, (3) adapts to communications disturbances by varying the density and movement of mobile nodes, and (4) new metrics to assess the performance of the EVSM algorithm. Simulation results show that EVSM provides up to 16% more coverage and is 3.5 times faster than VSM in environments with eight obstacles.

  11. EFFECT OF MOBILITY ON PERFORMANCE OF WIRELESS AD-HOC NETWORK PROTOCOLS.

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, M. V.; Marathe, A.

    2001-01-01

    We empirically study the effect of mobility on the performance of protocols designed for wireless adhoc networks. An important ohjective is to study the interaction of the Routing and MAC layer protocols under different mobility parameters. We use three basic mobility models: grid mobility model, random waypoint model, and exponential correlated random model. The performance of protocols was measured in terms of (i) latency, (ii) throughput, (iii) number of packels received, (iv) long term fairness and (v) number of control packets at the MAC layer level. Three different commonly studied routing protocols were used: AODV, DSR and LAR1. Similarly three well known MAC protocols were used: MACA, 802.1 1 and CSMA. The inair1 conclusion of our study include the following: 1. 'I'he performance of the: network varies widely with varying mobility models, packet injection rates and speeds; and can ba in fact characterized as fair to poor depending on the specific situation. Nevertheless, in general, it appears that the combination of AODV and 802.1 I is far better than other combination of routing and MAC protocols. 2. MAC layer protocols interact with routing layer protocols. This concept which is formalized using statistics implies that in general it is not meaningful to speak about a MAC or a routing protocol in isolation. Such an interaction leads to trade-offs between the amount of control packets generated by each layer. More interestingly, the results wise the possibility of improving the performance of a particular MAC layer protocol by using a cleverly designed routing protocol or vice-versa. 3. Routing prolocols with distributed knowledge about routes are more suitable for networks with mobility. This is seen by comparing the performance of AODV with DSR or LAR scheme 1. In DSli and IAR scheme 1, information about a computed path is being stored in the route query control packct. 4. MAC layer protocols have varying performance with varying mobility models. It is

  12. Dynamic spectrum access in wireless ad hoc networks: issues and possible solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Zhensheng; Soni, Tarun

    2010-04-01

    In this paper, we present a brief overview on the recent development of the dynamical spectrum access (DSA) techniques, focusing on the following areas: characteristics of the available bandwidth of the primary users, sensing technologies and sensing intervals to detect white spaces, spectrum allocation and management, reliability of the secondary user, tradeoff between spectrum/performance gain versus additional overhead used in implementing DSA, and cross layer optimization in spectrum sharing. Some of tradeoff studies are presented in terms of price of anarchy, which is defined as the price that a decentralized system should pay for not being coordinated. We will also discuss some of the open issues in deploying DSA.

  13. The Ad Hoc Mars Airplane science working group. [remotely piloted airplane as a Mars exploration vehicle

    NASA Technical Reports Server (NTRS)

    Clarke, V. C., Jr.

    1978-01-01

    The capability of a remotely piloted airplane as a Mars exploration vehicle in the aerial survey mode is assessed. Specific experiment areas covered include: visual imaging; gamma ray and infrared reflectance spectroscopy; gravity field; magnetic field and electromagnetic sounding; and atmospheric composition and dynamics. It is concluded that (1) the most important use of a plane in the aerial survey mode would be in topical studies and returned sample site characterization; (2) the airplane offers the unique capability to do high resolution, oblique imaging, and repeated profile measurements in the atmospheric boundary layer; and (3) it offers the best platform from which to do electromagnetic sounding.

  14. Do we need an Ad hoc chemical mechanism for Mexico City's photochemical smog?

    NASA Astrophysics Data System (ADS)

    Ruiz-Suárez, L. G.; Castro, T.; Mar, B.; Ruiz-Santoyo, M. E.; Cruz, X.

    Chemical mechanisms in mathematical models for air quality studies represent the synthesis of about 30 years of research in gas kinetics and atmospheric chemistry, and are able to represent, to a good extent, the chemistry of photochemical smog. However, due to the large amount of computer resources required by these models, different well-known approaches have been used in order to make them operative. In any of these approaches, a set of educated guesses is made, based upon the knowledge of the conditions under which the reactions occur and the competition between them, and upon the expected absolute and relative concentrations of the emitted reactive organic gases (ROG). Are those educated guesses applicable to Mexico City? Do we know enough how the prevalent conditions of temperature, total pressure, ultraviolet irradiation and water content in the atmosphere operate over the chemistry of photochemical smog? An answer to these questions has been attempted by performing variational analysis of selected hydrocarbons. Some results for n-butane, propene and trans-2-butene are shown; they show that under conditions of high reactivity, some assumptions may not be applicable to Mexico City. Also, the results serve to show the applicability of the method to preliminary reactivity studies.

  15. Rapid self-organised initiation of ad hoc sensor networks close above the percolation threshold

    NASA Astrophysics Data System (ADS)

    Korsnes, Reinert

    2010-07-01

    This work shows potentials for rapid self-organisation of sensor networks where nodes collaborate to relay messages to a common data collecting unit (sink node). The study problem is, in the sense of graph theory, to find a shortest path tree spanning a weighted graph. This is a well-studied problem where for example Dijkstra’s algorithm provides a solution for non-negative edge weights. The present contribution shows by simulation examples that simple modifications of known distributed approaches here can provide significant improvements in performance. Phase transition phenomena, which are known to take place in networks close to percolation thresholds, may explain these observations. An initial method, which here serves as reference, assumes the sink node starts organisation of the network (tree) by transmitting a control message advertising its availability for its neighbours. These neighbours then advertise their current cost estimate for routing a message to the sink. A node which in this way receives a message implying an improved route to the sink, advertises its new finding and remembers which neighbouring node the message came from. This activity proceeds until there are no more improvements to advertise to neighbours. The result is a tree network for cost effective transmission of messages to the sink (root). This distributed approach has potential for simple improvements which are of interest when minimisation of storage and communication of network information are a concern. Fast organisation of the network takes place when the number k of connections for each node ( degree) is close above its critical value for global network percolation and at the same time there is a threshold for the nodes to decide to advertise network route updates.

  16. A probabilistic dynamic energy model for ad-hoc wireless sensors network with varying topology

    NASA Astrophysics Data System (ADS)

    Al-Husseini, Amal

    In this dissertation we investigate the behavior of Wireless Sensor Networks (WSNs) from the degree distribution and evolution perspective. In specific, we focus on implementation of a scale-free degree distribution topology for energy efficient WSNs. WSNs is an emerging technology that finds its applications in different areas such as environment monitoring, agricultural crop monitoring, forest fire monitoring, and hazardous chemical monitoring in war zones. This technology allows us to collect data without human presence or intervention. Energy conservation/efficiency is one of the major issues in prolonging the active life WSNs. Recently, many energy aware and fault tolerant topology control algorithms have been presented, but there is dearth of research focused on energy conservation/efficiency of WSNs. Therefore, we study energy efficiency and fault-tolerance in WSNs from the degree distribution and evolution perspective. Self-organization observed in natural and biological systems has been directly linked to their degree distribution. It is widely known that scale-free distribution bestows robustness, fault-tolerance, and access efficiency to system. Fascinated by these properties, we propose two complex network theoretic self-organizing models for adaptive WSNs. In particular, we focus on adopting the Barabasi and Albert scale-free model to fit into the constraints and limitations of WSNs. We developed simulation models to conduct numerical experiments and network analysis. The main objective of studying these models is to find ways to reducing energy usage of each node and balancing the overall network energy disrupted by faulty communication among nodes. The first model constructs the wireless sensor network relative to the degree (connectivity) and remaining energy of every individual node. We observed that it results in a scale-free network structure which has good fault tolerance properties in face of random node failures. The second model considers

  17. Medium Access in Spread-Spectrum Ad Hoc Networks with Multiuser Detection

    NASA Astrophysics Data System (ADS)

    Kusume, Katsutoshi; Vilzmann, Robert; Müller, Andreas; Hartmann, Christian; Bauch, Gerhard

    2008-12-01

    Conventional medium access control protocols are designed to avoid simultaneous transmissions, based on a simple collision model in the underlying physical layer. Recently, strong physical layer capabilities, enabled by multiuser detection techniques, have been studied in connection with simple medium access control protocols, for example, slotted ALOHA. We think that neither of these extreme approaches is optimum, particularly in general scenarios where network nodes with different signal processing capabilities coexist. Instead of dealing with interferences in either of the two layers alone, both medium access control and physical layer functionalities should be designed to cooperate and complement each other. We discuss several key aspects for designing such a protocol, especially with an emphasis on iterative multiuser detection, which can provide a good tradeoff between performance and complexity. We propose a new protocol called MUD-MAC which satisfies these key aspects. We analyze its throughput bound and also perform numerical simulations. The simulation results show excellent throughput improvements. It is also demonstrated that the MUD-MAC protocol provides certain fairness among network nodes with different signal processing capabilities.

  18. 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…

  19. Adaptive Wireless Ad-hoc Sensor Networks for Long-term and Event-oriented Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Bumberger, Jan; Mollenhauer, Hannes; Remmler, Paul; Schaedler, Martin; Schima, Robert; Mollenhauer, Olaf; Hutschenreuther, Tino; Toepfer, Hannes; Dietrich, Peter

    2015-04-01

    Ecosystems are often characterized by their high heterogeneity, complexity and dynamic. Hence, single point measurements are often not sufficient for their complete representation. The application of wireless sensor networks in terrestrial and aquatic environmental systems offer significant benefits as a better consideration to the local test conditions, due to the simple adjustment of the sensor distribution, the sensor types and the sample rate. Another advantage of wireless ad-hoc sensor networks is their self-organizing behavior, resulting in a major reduction in installation and operation costs and time. In addition, individual point measurements with a sensor are significantly improved by measuring at several points continuously. In this work a concept and realization for Long-term ecosystem research is given in the field monitoring of micrometeorology and soil parameters for the interaction of biotic and abiotic processes. This long term analyses are part of the Global Change Experimental Facility (GCEF), a large field-based experimental platform to assess the effects of climate change on ecosystem functions and processes under different land-use scenarios. Regarding to the adaptive behavior of the network, also a mobile version was developed to overcome the lack of information of temporally and spatially fixed measurements for the detection and recording of highly dynamic or time limited processes. First results of different field campaigns are given to present the potentials and limitations of this application in environmental science, especially for the monitoring of the interaction of biotic and abiotic processes, soil-atmosphere interaction and the validation of remote sensing data.

  20. Adaptive Wireless Ad-hoc Sensor Networks for Long-term and Event-oriented Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Bumberger, Jan; Mollenhauer, Hannes; Remmler, Paul; Chirila, Andrei Marian; Mollenhauer, Olaf; Hutschenreuther, Tino; Toepfer, Hannes; Dietrich, Peter

    2016-04-01

    Ecosystems are often characterized by their high heterogeneity, complexity and dynamic. Hence, single point measurements are often not sufficient for their complete representation. The application of wireless sensor networks in terrestrial and aquatic environmental systems offer significant benefits as a better consideration to the local test conditions, due to the simple adjustment of the sensor distribution, the sensor types and the sample rate. Another advantage of wireless ad-hoc sensor networks is their self-organizing behavior, resulting in a major reduction in installation and operation costs and time. In addition, individual point measurements with a sensor are significantly improved by measuring at several points continuously. In this work a concept and realization for Long-term ecosystem research is given in the field monitoring of micrometeorology and soil parameters for the interaction of biotic and abiotic processes. This long term analyses are part of the Global Change Experimental Facility (GCEF), a large field-based experimental platform to assess the effects of climate change on ecosystem functions and processes under different land-use scenarios. Regarding to the adaptive behavior of the network, also a mobile version was developed to overcome the lack of information of temporally and spatially fixed measurements for the detection and recording of highly dynamic or time limited processes. First results of different field campaigns are given to present the potentials and limitations of this application in environmental science, especially for the monitoring of the interaction of biotic and abiotic processes, soil-atmosphere interaction and the validation of remote sensing data.

  1. Development of Innovative and Inexpensive Optical Sensors in Wireless Ad-hoc Sensor Networks for Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Mollenhauer, Hannes; Schima, Robert; Assing, Martin; Mollenhauer, Olaf; Dietrich, Peter; Bumberger, Jan

    2015-04-01

    Due to the heterogeneity and dynamic of ecosystems, the observation and monitoring of natural processes necessitate a high temporal and spatial resolution. This also requires inexpensive and adaptive measurements as well as innovative monitoring strategies. To this end, the application of ad-hoc wireless sensor networks holds the potential of creating an adequate monitoring platform. In order to achieve a comprehensive monitoring in space and time with affordability, it is necessary to reduce the sensor costs. Common investigation methods, especially with regard to vegetation processes, are based on optical measurements. In particular, different wavelengths correspond to specific properties of the plants and preserve the possibility to derive information about the ecosystem, e.g. photosynthetic performance or nutrient content. In this context, photosynthetically active radiation (PAR) sensors and hyperspectral sensors are in major use. This work aims the development, evaluation and application of inexpensive but high performance optical sensors for the implementation in wireless sensor networks. Photosynthetically active radiation designates the spectral range from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. PAR sensors enable the detection of the reflected solar light of the vegetation in the whole PAR wave band. The amount of absorption indicates photosynthetic activity of the plant, with good approximation. Hyperspectral sensors observe specific parts or rather distinct wavelengths of the solar light spectrum and facilitate the determination of the main pigment classes, e.g. Chlorophyll, Carotenoid and Anthocyanin. Due to the specific absorption of certain pigments, a characteristic spectral signature can be seen in the visible part of the electromagnetic spectrum, known as narrow-band peaks. In an analogous manner, also the presence and concentration of different nutrients cause a characteristic spectral

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

    PubMed Central

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

    2016-01-01

    Background. 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. Method. 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. Results. 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. Conclusion. 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. PMID:27127653

  3. A Security Solution for IEEE 802.11's Ad-hoc Mode:Password-Authentication and Group Diffie-Hellman Key Exchange

    SciTech Connect

    Emmanuel, Bresson; Olivier, Chevassut; David, Pointcheval

    2005-10-01

    The IEEE 802 standards ease the deployment of networkinginfrastructures and enable employers to accesscorporate networks whiletraveling. These standards provide two modes of communication calledinfrastructure and ad-hoc modes. A security solution for the IEEE802.11's infrastructure mode took several years to reach maturity andfirmware are still been upgraded, yet a solution for the ad-hoc modeneeds to be specified. The present paper is a first attempt in thisdirection. It leverages the latest developments in the area ofpassword-based authentication and (group) Diffie-Hellman key exchange todevelop a provably-secure key-exchange protocol for IEEE 802.11's ad-hocmode. The protocol allows users to securely join and leave the wirelessgroup at time, accommodates either a single-shared password orpairwise-shared passwords among the group members, or at least with acentral server; achieves security against dictionary attacks in theideal-hash model (i.e. random-oracles). This is, to the best of ourknowledge, the first such protocol to appear in the cryptographicliterature.

  4. An ab initio molecular dynamics study of the roaming mechanism of the H2+HOC+ reaction

    NASA Astrophysics Data System (ADS)

    Yu, Hua-Gen

    2011-08-01

    We report here a direct ab initio molecular dynamics study of the p-/o-H2+HOC+ reaction on the basis of the accurate SAC-MP2 potential energy surface. The quasi-classical trajectory method was employed. This work largely focuses on the study of reaction mechanisms. A roaming mechanism was identified for this molecular ion-molecule reaction. The driving forces behind the roaming mechanism were thoroughly investigated by using a trajectory dynamics approach. In addition, the thermal rate coefficients of the H2+HOC+ reaction were calculated in the temperature range [25, 300] K and are in good agreement with experiments.

  5. Criteria for intraventricular conduction disturbances and pre-excitation. World Health Organizational/International Society and Federation for Cardiology Task Force Ad Hoc.

    PubMed

    Willems, J L; Robles de Medina, E O; Bernard, R; Coumel, P; Fisch, C; Krikler, D; Mazur, N A; Meijler, F L; Mogensen, L; Moret, P

    1985-06-01

    In an effort to standardize terminology and criteria for clinical electrocardiography, and as a follow-up of its work on definitions of terms related to cardiac rhythm, an Ad Hoc Working Group established by the World Health Organization and the International Society and Federation of Cardiology reviewed criteria for the diagnosis of conduction disturbances and pre-excitation. Recommendations resulting from these discussions are summarized for the diagnosis of complete and incomplete right and left bundle branch block, left anterior and left posterior fascicular block, nonspecific intraventricular block, Wolff-Parkinson-White syndrome and related pre-excitation patterns. Criteria for intraatrial conduction disturbances are also briefly reviewed. The criteria are described in clinical terms. A concise description of the criteria using formal Boolean logic is given in the Appendix. For the incorporation into computer electrocardiographic analysis programs, the limits of some interval measurements may need to be adjusted. PMID:3889097

  6. 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.

  7. 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

  8. 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

  9. Ad Hoc Conference on the Education of Migrants: Introductory Report on Theme III, "Opportunities for Vocational and Technical Training and General Education for Adults and Adolescents" (Strasbourg, France, November 5-8, 1974).

    ERIC Educational Resources Information Center

    Egger, Eugene

    Theme III of the Ad Hoc Conference on the Education of Migrants was "measures to secure the satisfactory provision of opportunities for vocational and technical training and general education for adults and adolescents". This report briefly summarizes the situation in member countries regarding the vocational and technical training and general…

  10. Neural methods based on modified reputation rules for detection and identification of intrusion attacks in wireless ad hoc sensor networks

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2010-04-01

    Determining methods to secure the process of data fusion against attacks by compromised nodes in wireless sensor networks (WSNs) and to quantify the uncertainty that may exist in the aggregation results is a critical issue in mitigating the effects of intrusion attacks. Published research has introduced the concept of the trustworthiness (reputation) of a single sensor node. Reputation is evaluated using an information-theoretic concept, the Kullback- Leibler (KL) distance. Reputation is added to the set of security features. In data aggregation, an opinion, a metric of the degree of belief, is generated to represent the uncertainty in the aggregation result. As aggregate information is disseminated along routes to the sink node(s), its corresponding opinion is propagated and regulated by Josang's belief model. By applying subjective logic on the opinion to manage trust propagation, the uncertainty inherent in aggregation results can be quantified for use in decision making. The concepts of reputation and opinion are modified to allow their application to a class of dynamic WSNs. Using reputation as a factor in determining interim aggregate information is equivalent to implementation of a reputation-based security filter at each processing stage of data fusion, thereby improving the intrusion detection and identification results based on unsupervised techniques. In particular, the reputation-based version of the probabilistic neural network (PNN) learns the signature of normal network traffic with the random probability weights normally used in the PNN replaced by the trust-based quantified reputations of sensor data or subsequent aggregation results generated by the sequential implementation of a version of Josang's belief model. A two-stage, intrusion detection and identification algorithm is implemented to overcome the problems of large sensor data loads and resource restrictions in WSNs. Performance of the twostage algorithm is assessed in simulations of WSN

  11. CIRRPC Science Panel report No. 3 and 2: Review of the report of the National Institutes of Health Ad Hoc Working Group to Develop Radioepidemiological Tables

    SciTech Connect

    1985-01-01

    This report of the Science Panel supplements an earlier document (included), which summarized the Panel`s views on the September, 1984, draft report of the National Institutes of Health Ad Hoc Working Group to Develop Radioepidemiological Tables. Although the Orphan Drug Act requires that tables be produced for a range of dose from one millirad to 1000 rad, the Working Group chose to make no estimates below one rad. The Science Panel is in agreement with this judgment because in the low-dose range there is little empirical evidence of a carcinogenic effect in humans. In order for the Tables to be applicable, a person must have both one of the cancers listed in the Tables and a previous exposure to ionizing radiation. Therefore, the Tables should not be applied to determine the likelihood that a person having received a specific radiation dose will have such a cancer. The Panel`s previous recommendations were primarily concerned with three issues, use of Quality Factors, use of tables for exposures from internally deposited radionuclides, and treatment of uncertainties. In the final report, the Working Group has dispensed with the use of Quality Factors in treating the risks from internally deposited alpha emitters and has substantially expanded on its treatment of uncertainties. The Science Panel`s comments on these changes and other aspects of the report are included.

  12. Ad-hoc design of temporally shaped fs laser pulses based on plasma dynamics for deep ablation in fused silica

    NASA Astrophysics Data System (ADS)

    Hernandez-Rueda, J.; Siegel, J.; Puerto, D.; Galvan-Sosa, M.; Gawelda, W.; Solis, J.

    2013-07-01

    We have analyzed the ablation depth yield of fused silica irradiated with shaped pulse trains with a separation of 500 fs and increasing or decreasing intensity envelopes. This temporal separation value is extracted from previous studies on ablation dynamics upon irradiation with transform-limited 100 fs laser pulses. The use of decreasing intensity pulse trains leads to a strong increase of the induced ablation depth when compared to the behavior, at the same pulse fluence, of intensity increasing pulse trains. In addition, we have studied the material response under stretched (500 fs, FWHM) and transform-limited (100 fs, FWHM) pulses, for which avalanche or multiphoton ionization respectively dominates the carrier generation process. The comparison of the corresponding evolution of the ablated depth vs. fluence suggests that the use of pulse trains with decreasing intensity at high fluences should lead to enhanced single exposure ablation depths, beyond the limits corresponding to MPI- or AI-alone dominated processes.

  13. Critical gaps in the world's largest electronic medical record: Ad Hoc nursing narratives and invisible adverse drug events.

    PubMed

    Hurdle, John F; Weir, Charlene R; Roth, Beverly; Hoffman, Jennifer; Nebeker, Jonathan R

    2003-01-01

    The Veterans Health Administration (VHA), of the U.S. Department of Veteran Affairs, operates one of the largest healthcare networks in the world. Its electronic medical record (EMR) is fully integrated into clinical practice, having evolved over several decades of design, testing, trial, and error. It is unarguably the world's largest EMR, and as such it makes an important case study for a host of timely informatics issues. The VHA consistently has been at the vanguard of patient safety, especially in its provider-oriented EMR. We describe here a study of a large set of adverse drug events (ADEs) that eluded a rigorous ADE survey based on prospective EMR chart review. These numerous ADEs were undetected (and hence invisible) in the EMR, missed by an otherwise sophisticated ADE detection scheme. We speculate how these invisible nursing ADE narratives persist and what they portend for safety re-engineering. PMID:14728184

  14. Immunization coverage among splenectomized patients: Results of an ad hoc survey in Puglia Region (South of Italy).

    PubMed

    Martino, Carmen; Gallone, Maria Serena; Quarto, Michele; Germinario, Cinzia; Tafuri, Silvio

    2016-05-01

    Patients with anatomic or functional asplenia have a 10-50 times higher risk than general population to develop Overwhelming Post-Splenectomy Infection. Evidences are unanimous in recommending splenectomised patients to receive meningococcal, antipneumococcal and Haemophilus influenzae type B vaccinations according to a specific timing. In Italy there are no current data on the immunisation coverage in these patients. This study aims to investigate immunisation coverage in patients undergoing elective or urgent splenectomy for 2012-2013 in the 3 Apulian hospitals. The patients discharged with the code ICD-9-CM 41.5 - "Total splenectomy" were enrolled. The administration of vaccines was verified through consultation of medical records, archives of general practitioners and vaccination offices. In the study period, 166 subjects underwent splenectomy and none of them received vaccinations during hospitalization. 25 splenectomised patients (15.1%) received at least one of the recommended vaccinations. 21 patients (12.6%) received vaccine against Streptococcus pneumonia, 13 (7.8%) meningococcal vaccine, 10 patients (6%) Haemophilus influenzae type B vaccine. The low vaccination coverage could be due both to poor perception of the risk of infection and to a lack of knowledge on vaccinations by surgeons. For this reason it is necessary to draw up and share operational protocols that establish the administration of vaccines. PMID:26890256

  15. Delay Analysis of Max-Weight Queue Algorithm for Time-Varying Wireless Ad hoc Networks—Control Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Chen, Junting; Lau, Vincent K. N.

    2013-01-01

    Max weighted queue (MWQ) control policy is a widely used cross-layer control policy that achieves queue stability and a reasonable delay performance. In most of the existing literature, it is assumed that optimal MWQ policy can be obtained instantaneously at every time slot. However, this assumption may be unrealistic in time varying wireless systems, especially when there is no closed-form MWQ solution and iterative algorithms have to be applied to obtain the optimal solution. This paper investigates the convergence behavior and the queue delay performance of the conventional MWQ iterations in which the channel state information (CSI) and queue state information (QSI) are changing in a similar timescale as the algorithm iterations. Our results are established by studying the stochastic stability of an equivalent virtual stochastic dynamic system (VSDS), and an extended Foster-Lyapunov criteria is applied for the stability analysis. We derive a closed form delay bound of the wireless network in terms of the CSI fading rate and the sensitivity of MWQ policy over CSI and QSI. Based on the equivalent VSDS, we propose a novel MWQ iterative algorithm with compensation to improve the tracking performance. We demonstrate that under some mild conditions, the proposed modified MWQ algorithm converges to the optimal MWQ control despite the time-varying CSI and QSI.

  16. 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

  17. 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

  18. Spin Filtering Studies at COSY and AD

    SciTech Connect

    Nass, Alexander

    2009-08-04

    The high physics potential of experiments with stored high-energy polarized antiprotons led to the proposal of PAX (Polarized Antiproton eXperiment) 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/Juelich) as well as antiprotons (at AD/CERN) will be carried out to test the principle and measure p-barp-vector and p-bard-vector cross sections. A polarized internal gas target (PIT) with surrounding Silicon detectors immersed into a low-beta section has to be set up.

  19. Analytical study on holographic superfluid in AdS soliton background

    NASA Astrophysics Data System (ADS)

    Lai, Chuyu; Pan, Qiyuan; Jing, Jiliang; Wang, Yongjiu

    2016-06-01

    We analytically study the holographic superfluid phase transition in the AdS soliton background by using the variational method for the Sturm-Liouville eigenvalue problem. By investigating the holographic s-wave and p-wave superfluid models in the probe limit, we observe that the spatial component of the gauge field will hinder the phase transition. Moreover, we note that, different from the AdS black hole spacetime, in the AdS soliton background the holographic superfluid phase transition always belongs to the second order and the critical exponent of the system takes the mean-field value in both s-wave and p-wave models. Our analytical results are found to be in good agreement with the numerical findings.

  20. 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…

  1. 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…

  2. 78 FR 8145 - Sequence 24 Findings of the EISA 436(h) Ad-Hoc Review Group on Green Building Certification Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-05

    ... Administrator to provide his/her recommendation to the Secretary of Energy, who then consults with the Secretary... identify a system and certification level that ``will be most likely to encourage a comprehensive and... ] harmonizing Federal green building activities with the private sector. To read the full study, please...

  3. Results from Ad Hoc and Routinely Collected Data among Celiac Women with Infertility or Pregnancy Related Disorders: Italy, 2001–2011

    PubMed Central

    2014-01-01

    Celiac disease (CD) is a chronic autoimmune illness triggered by gluten consumption in genetically predisposed individuals. Worldwide, CD prevalence is approximately 1%. Several studies suggest a higher prevalence of undiagnosed CD in patients with infertility. We described reproductive disorders and assessed the frequency of hospital admissions for infertility among celiac women aged 15–49. We conducted two surveys enrolling a convenient sample of celiac women, residing in Apulia or in Basilicata (Italy). Moreover, we selected hospital discharge records (HDRs) of celiac women and women with an exemption for CD, and matched the lists with HDRs for reproductive disorders. In the surveys we included 91 celiac women; 61.5% of them reported menstrual cycle disorders. 47/91 reported at least one pregnancy and 70.2% of them reported problems during pregnancy. From the HDRs and the registry of exemption, we selected 4,070 women with CD; the proportion of women hospitalized for infertility was higher among celiac women than among resident women in childbearing age (1.2% versus 0.2%). Our findings highlight a higher prevalence of reproductive disorders among celiac women than in the general population suggesting that clinicians might consider testing for CD women presenting with pregnancy disorders or infertility. PMID:24895657

  4. Results from ad hoc and routinely collected data among celiac women with infertility or pregnancy related disorders: Italy, 2001-2011.

    PubMed

    Fortunato, Francesca; Martinelli, Domenico; Prato, Rosa; Pedalino, Biagio

    2014-01-01

    Celiac disease (CD) is a chronic autoimmune illness triggered by gluten consumption in genetically predisposed individuals. Worldwide, CD prevalence is approximately 1%. Several studies suggest a higher prevalence of undiagnosed CD in patients with infertility. We described reproductive disorders and assessed the frequency of hospital admissions for infertility among celiac women aged 15-49. We conducted two surveys enrolling a convenient sample of celiac women, residing in Apulia or in Basilicata (Italy). Moreover, we selected hospital discharge records (HDRs) of celiac women and women with an exemption for CD, and matched the lists with HDRs for reproductive disorders. In the surveys we included 91 celiac women; 61.5% of them reported menstrual cycle disorders. 47/91 reported at least one pregnancy and 70.2% of them reported problems during pregnancy. From the HDRs and the registry of exemption, we selected 4,070 women with CD; the proportion of women hospitalized for infertility was higher among celiac women than among resident women in childbearing age (1.2% versus 0.2%). Our findings highlight a higher prevalence of reproductive disorders among celiac women than in the general population suggesting that clinicians might consider testing for CD women presenting with pregnancy disorders or infertility. PMID:24895657

  5. Spaceborne Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Forcada, Ignasi; Strauss, Adi

    2010-08-01

    Reliable global networking is essential for a rapidly growing mobile and interactive communication. Satellite communication plays already a significant role in this subject. However, the classical space-based data transmission requires an appropriate infrastructure, both on the ground and in orbit. This paper discusses the potential of a self-organising distributed satellite system in Low Earth Orbits (LEO) to achieve a seamless integration in already existing infrastructures. The communication approach is based on dynamic Inter Satellite Links (ISL) not controlled nor coordinated on an individual basis from the ground-based stations.

  6. 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…

  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. PMID:25388303

  8. Bioavailability of HOC depending on the colloidal state of humic substances: a case study with PCB-77 and Daphnia magna.

    PubMed

    Gallé, T; Grégoire, Ch; Wagner, M; Bierl, R

    2005-10-01

    Condensed organic matter with higher affinity for hydrophobic organic compounds (HOC) is currently held responsible for slow desorption and concomitant lower bioavailabilities of HOC in sediments and soils. In an experiment with Daphnia magna and IHSS Peat Humic Acid (PHA), we showed that the bioconcentration factor (BCF) of 3,3',4,4'-tetrachlorobiphenyl (PCB-77) was directly related to the charge of the humic colloid, as predicted by the metal-humic binding model WHAM. Consistent with the type of binding to the humic acid (counter-ion accumulation vs. specific binding), increasing the concentration of Na+ and Ca2+ ions generated opposite effects on colloid charge and HOC binding by the humic acid. Condensation as a colloidal phenomenon in solution as well as on surfaces needs to be addressed as a contributor to lower bioavailabilities and, possibly, to slower desorption kinetics. PMID:15967482

  9. The Added Value of Study Abroad: Fostering a Global Citizenry

    ERIC Educational Resources Information Center

    Tarrant, Michael A.; Rubin, Donald L.; Stoner, Lee

    2014-01-01

    Few studies have employed experimental designs adequate for documenting the value added of studying abroad; that is, learning outcomes above and beyond that which may be achieved in domestic or traditional campus-based courses. Using a pre-/posttest, two-by-two factor design of course location (study abroad vs. home campus) by course subject…

  10. Concise review: no breakthroughs for human mesenchymal and embryonic stem cell culture: conditioned medium, feeder layer, or feeder-free; medium with fetal calf serum, human serum, or enriched plasma; serum-free, serum replacement nonconditioned medium, or ad hoc formula? All that glitters is not gold!

    PubMed

    Mannello, Ferdinando; Tonti, Gaetana A

    2007-07-01

    The choice of an optimal strategy of stem cell culture is at the moment an impossible task, and the elaboration of a culture medium adapted to the production of embryonic and adult mesenchymal stem cells for the clinical application of cell therapy remains a crucial matter. To make an informed choice, it is crucial to not underestimate the theoretical health risk of using xenogenic compounds, to limit the immunological reactions once stem cells are transplanted, to not overestimate the controversial results obtained with human serum, plasma, and blood derivatives, as well as to carefully examine the pros and cons of serum-free and ad hoc formulation strategies; besides that, to also maintain multipotentiality, self-renewal, and transplantability. The extent to which we are able to achieve effective cell therapies will depend on assimilating a rapidly developing base of scientific knowledge with the practical considerations of design, delivery, and host response. Although clinical studies have already started, many questions remain unsolved, and concomitantly even more evidence on suitable and safe off-the-shelf products (mainly xeno-free) for embryonic and mesenchymal stem cells is cropping up, even though there should be no rush to enter the clinical stage while the underlying basic research is still not so solid; this solely will lead to high-quality translational research, without making blunders stemming from the assumption that all that glitters is not gold. Disclosure of potential conflicts of interest is found at the end of this article. PMID:17395775

  11. Cognitive Impact of Banner Ad Characteristics: An Experimental Study.

    ERIC Educational Resources Information Center

    Li, Hairong; Bukovac, Janice L.

    1999-01-01

    Finds that (1) animated banner ads (display advertisements hyperlinked to an advertiser's Web site) result in quicker response and better recall (from college students) than non-animated banner ads; (2) larger banner ads lead to better comprehension and more clicks than small banner ads; and (3) user mode (information seeking or Web surfing) did…

  12. The “Gender Factor” in Wearing-Off among Patients with Parkinson's Disease: A Post Hoc Analysis of DEEP Study

    PubMed Central

    Colombo, Delia; Abbruzzese, Giovanni; Antonini, Angelo; Barone, Paolo; Bellia, Gilberto; Franconi, Flavia; Attar, Mahmood; Zagni, Emanuela; Haggiag, Shalom; Stocchi, Fabrizio

    2015-01-01

    Background. The early detection of wearing-off in Parkinson disease (DEEP) observational study demonstrated that women with Parkinson's disease (PD) carry an increased risk (80.1%) for wearing-off (WO). This post hoc analysis of DEEP study evaluates gender differences on WO and associated phenomena. Methods. Patients on dopaminergic treatment for ≥1 year were included in this multicenter observational cross-sectional study. In a single visit, WO was diagnosed based on neurologist assessment as well as the use of the 19-item wearing-off questionnaire (WOQ-19); WO was defined for scores ≥2. Post hoc analyses were conducted to investigate gender difference for demographic and clinical features with respect to WO. Results. Of 617 patients enrolled, 236 were women and 381 were men. Prevalence of WO was higher among women, according to both neurologists' judgment (61.9% versus 53.8%, P = 0.045) and the WOQ-19 analysis (72.5% versus 64.0%, P = 0.034). In patients with WO (WOQ-19), women experienced ≥1 motor symptom in 72.5% versus 64.0% in men and ≥1 nonmotor symptom in 44.5% versus 36.7%, in men. Conclusions. Our results suggest WO as more common among women, for both motor and nonmotor symptoms. Prospective studies are warranted to investigate this potential gender-effect. PMID:25685848

  13. Multichannel MAC Layer In Mobile Ad—Hoc Network

    NASA Astrophysics Data System (ADS)

    Logesh, K.; Rao, Samba Siva

    2010-11-01

    This paper we presented the design objectives and technical challenges in Multichannel MAC protocols in Mobile Ad-hoc Network. In IEEE 802.11 a/b/g standards allow use of multiple channels, only a single channel is popularly used, due to the lack of efficient protocols that enable use of Multiple Channels. Even though complex environments in ad hoc networks require a combined control of physical (PHY) and medium access control (MAC) layers resources in order to optimize performance. And also we discuss the characteristics of cross-layer frame and give a multichannel MAC approach.

  14. Spin-Filtering studies at COSY and AD

    SciTech Connect

    Nass, Alexander

    2008-02-06

    An overview on the present understanding of the methods to polarize an antiproton beam is given and the planned measurements on spin filtering at COSY and AD rings with protons and antiprotons are described. The experimental setup which is being prepared for these measurements is described and focus is given on the polarized internal target.

  15. 17 CFR 240.17Ad-13 - Annual study and evaluation of internal accounting control.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... internal accounting control. 240.17Ad-13 Section 240.17Ad-13 Commodity and Securities Exchanges SECURITIES... Company Rules § 240.17Ad-13 Annual study and evaluation of internal accounting control. (a) Accountant's... accountant concerning the transfer agent's system of internal accounting control and related procedures...

  16. 3-D Resistivity Tomography for Cliff Stability Study at the D-Day Pointe du Hoc Historic Site in Normandy, France

    NASA Astrophysics Data System (ADS)

    Udphuay, S.; Everett, M. E.; Guenther, T.; Warden, R. R.

    2007-12-01

    The D-Day invasion site at Pointe du Hoc in Normandy, France is one of the most important World War II battlefields. The site remains today a valuable historic cultural resource. However the site is vulnerable to cliff collapses that could endanger the observation post building and U.S. Ranger memorial located just landward of the sea stack, and an anti-aircraft gun emplacement, Col. Rudder's command post, located on the cliff edge about 200 m east of the observation post. A 3-D resistivity tomography incorporating extreme topography is used in this study to provide a detailed site stability assessment with special attention to these two buildings. Multi-electrode resistivity measurements were made across the cliff face and along the top of the cliff around the two at-risk buildings to map major subsurface fracture zones and void spaces that could indicate possible accumulations and pathways of groundwater. The ingress of acidic groundwater through the underlying carbonate formations enlarges pre-existing tectonic fractures via limestone dissolution and weakens the overall structural integrity of the cliff. The achieved 3-D resistivity tomograms provide diagnostic subsurface resistivity distributions. Resistive zones associated with subsurface void spaces have been located. These void spaces constitute a stability geohazard as they become significant drainage routes during and after periods of heavy rainfalls.

  17. Treatment of Pulmonary Embolism With Rivaroxaban: Outcomes by Simplified Pulmonary Embolism Severity Index Score from a Post Hoc Analysis of the EINSTEIN PE Study

    PubMed Central

    Fermann, Gregory J; Erkens, Petra M G; Prins, Martin H; Wells, Philip S; Pap, Ákos F; Lensing, Anthonie W A; Kline, Jeffrey

    2015-01-01

    Objectives The objective was to assess adverse outcomes in relation to the simplified Pulmonary Embolism Severity Index (PESI) score in patients treated with rivaroxaban or standard therapy in the phase III EINSTEIN PE study and to evaluate the utility of the simplified PESI score to identify low-risk pulmonary embolism (PE) patients. Methods A post hoc analysis of EINSTEIN PE data was performed to assess the efficacy and safety of rivaroxaban in patients with a range of simplified PESI scores. Recurrent venous thromboembolism, fatal PE, all-cause mortality, and major bleeding were stratified by simplified PESI scores of 0, 1, or ≥2 and according to treatment period at 7, 14, 30, and 90 days and at the end of the full intended treatment period. Results Simplified PESI scores could be calculated in 4,831 of the 4,832 randomized patients; of those, 53.6, 36.7, and 9.7% had PESI scores of 0, 1, and ≥2, respectively. Among patients with simplified PESI scores of 0 or 1, fatal PE, all-cause mortality, and other adverse outcomes were uncommon within the first 7, 14, and 30 days. Patients with simplified PESI scores of ≥2 had more frequent adverse outcomes. Major bleeding was lower in the rivaroxaban group, particularly in those with simplified PESI scores of 1 or ≥2. Conclusions The findings support using risk stratification with the simplified PESI score to identify low-risk patients with PE. PMID:25716463

  18. Effects of statins on the progression of cerebral white matter lesion: Post hoc analysis of the ROCAS (Regression of Cerebral Artery Stenosis) study.

    PubMed

    Mok, Vincent C T; Lam, Wynnie W M; Fan, Yu Hua; Wong, Adrian; Ng, Ping Wing; Tsoi, Tak Hon; Yeung, Vincent; Wong, Ka Sing

    2009-05-01

    Arteriosclerotic related cerebral white matter lesion (WML) is associated with increased risk of death, stroke, dementia, depression, gait disturbance, and urinary incontinence. We investigated the effects of statins on WML progression by performing a post hoc analysis on the ROCAS (Regression of Cerebral Artery Stenosis) study, which is a randomized, double-blind, placebo-controlled study evaluating the effects of statins upon asymptomatic middle cerebral artery stenosis progression among stroke-free individuals. Two hundreds and eight randomized subjects were assigned to either placebo (n = 102) or simvastatin 20 mg daily (n = 106) for 2 years. Baseline severity of WML was graded visually into none, mild, and severe. Volume (cm3) of WML was determined quantitatively at baseline and at end of study using a semi-automated method based on MRI. Primary outcome was the change in WML volume over 2 years. After 2 years of follow-up, there was no significant change in WML volume between the active and the placebo group as a whole. However, stratified analysis showed that for those with severe WML at baseline, the median volume increase in the active group (1.9 cm3) was less compared with that in the placebo group (3.0 cm3; P = 0.047). Linear multivariate regression analysis identified that baseline WML volume (beta = 0.63, P < 0.001) and simvastatin treatment (beta = -0.214, P = 0.043) independently predicted change in WML volume. Our findings suggest that statins may delay the progression of cerebral WML only among those who already have severe WML at baseline. PMID:19252811

  19. Effect of lurasidone dose on cognition in patients with schizophrenia: post-hoc analysis of a long-term, double-blind continuation study.

    PubMed

    Harvey, Philip D; Siu, Cynthia O; Ogasa, Masaaki; Loebel, Antony

    2015-08-01

    We previously reported that treatment with 160mg/d of lurasidone improved cognitive performance in a manner superior to placebo, quetiapine XR 600mg/d, and lurasidone 80mg/d, based on a 6-week randomized trial of patients with an acute exacerbation of schizophrenia. The objective of this post-hoc analysis was to explore the cognitive and functional performance of patients whose final doses of lurasidone were 40/80mg/d, 120mg/d, and 160mg/d compared to quetiapine XR 200-800mg/d (QXR) during a 6-month, double-blind continuation study that followed a short-term trial. Subjects who received final doses of lurasidone 120mg/d (n=77) and 160mg/d (n=49) showed significantly greater improvement in overall cognitive performance compared to QXR (n=85) at week 32 (month 6 of the extension study), while those on last doses of 40/80mg/d (n=25) showed a trend towards significance at week 32. Mean changes in neurocognitive composite z-score from pre-treatment baseline were significant for the 3 lurasidone final dose groups at both weeks 19 and 32, with composite change scores of z=1.53, z=1.43, and z=1.34 for the lurasidone 40/80mg/d, 120mg/d, and 160mg/d, respectively, at week 32. In contrast, the composite change score was not statistically significant in the overall quetiapine group (z=0.46), with none of the individual quetiapine doses showing any significant improvement. Functional capacity scores improved in all treatment groups. Our findings indicate improved cognitive performance in patients treated with each of the flexible doses of lurasidone 40-160mg/d, compared to quetiapine XR 200-800mg/d. All doses of lurasidone were superior to all doses of quetiapine for cognitive performance. PMID:26117157

  20. 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. PMID:25140350

  1. Ad Hoc Physical Hilbert Spaces in Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Fernández, Francisco M.; Garcia, Javier; Semorádová, Iveta; Znojil, Miloslav

    2015-12-01

    The overall principles of what is now widely known as PT-symmetric quantum mechanics are listed, explained and illustrated via a few examples. In particular, models based on an elementary local interaction V(x) are discussed as motivated by the naturally emergent possibility of an efficient regularization of an otherwise unacceptable presence of a strongly singular repulsive core in the origin. The emphasis is put on the constructive aspects of the models. Besides the overall outline of the formalism we show how the low-lying energies of bound states may be found in closed form in certain dynamical regimes. Finally, once these energies are found real we explain that in spite of a manifest non-Hermiticity of the Hamiltonian the time-evolution of the system becomes unitary in a properly amended physical Hilbert space.

  2. 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…

  3. 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.

  4. Safinamide as Add-On Therapy to Levodopa in Mid- to Late-Stage Parkinson’s Disease Fluctuating Patients: Post hoc Analysesof Studies 016 and SETTLE

    PubMed Central

    Cattaneo, Carlo; Sardina, Marco; Bonizzoni, Ermino

    2016-01-01

    Background: Studies 016 and SETTLE showed that safinamide was safe and effective as adjunct therapy in patients with advanced Parkinson’s disease (PD) and motor fluctuations. The addition of safinamide to a stable dose of levodopa alone or with other antiparkinsonian medications significantly increased ON time with no/non-troublesome dyskinesia, decreased OFF time and improved Parkinson’s symptoms. Objective: To evaluate the clinical effects of safinamide 100 mg/day on motor fluctuations and cardinal Parkinson’s symptoms in specific patient subgroups using pooled data from Studies 016 and SETTLE. Methods: Both studies were double blind, placebo-controlled, randomized, phase 3 trials which enrolled patients with mid- to late-stage PD experiencing motor fluctuations while receiving optimized and stable doses of levodopa, alone or with other dopaminergic treatments. The present post-hoc analyses assessed the change from baseline in ON time (with no or non-troublesome dyskinesia) and OFF time in subgroups of patients who were receiving only levodopa at baseline, who were classified as “mild fluctuators” (daily OFF time ≤4 h), and who were receiving concomitant dopaminergic therapy, with or without amantadine, and the effects of safinamide versus placebo on individual cardinal PD symptoms during ON time. Results: Safinamide significantly increased mean ON time (with no or non-troublesome dyskinesia) and reduced mean OFF time when used as first adjunct therapy in levodopa-treated patients and patients with mild motor fluctuations. Mean daily ON time (with no or non-troublesome dyskinesia) and OFF time were favorably changed, compared with placebo, to similar extents regardless of whether patients were receiving concomitant dopamine agonists, catechol-O-methyltransferase inhibitors and amantadine. Additionally, safinamide improved bradykinesia, rigidity, tremor and gait. Conclusions: Safinamide was a safe and effective first adjunct therapy in levodopa

  5. History of Depressive and Anxiety Disorders and Paroxetine Response in Patients With Irritable Bowel Syndrome: Post Hoc Analysis From a Placebo-Controlled Study

    PubMed Central

    Marks, David M.; Han, Changsu; Krulewicz, Stan; Pae, Chi-Un; Peindl, Kathleen; Patkar, Ashwin A.; Masand, Prakash S.

    2008-01-01

    Objective: Although irritable bowel syndrome (IBS) is highly comorbid with depressive and anxiety disorders, information on the clinical implications of this comorbidity is limited. We investigated whether a history of depressive and/or anxiety disorders was associated with response to treatment in a double-blind, randomized, placebo-controlled trial of paroxetine controlled release (CR) in IBS. Method: Seventy-two IBS subjects (diagnosed using Rome II criteria) were recruited from August 2003 to November 2005 and randomly assigned to receive flexibly dosed paroxetine CR (dose, 12.5–50 mg/day) or placebo for 12 weeks. The Mini-International Neuropsychiatric Interview (MINI-Plus version) was used to ascertain current (exclusionary) or past diagnoses of depressive and anxiety disorders. Subjective depression, anxiety, and stress were assessed at entry and throughout the trial using the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and Perceived Stress Scale (PSS). Severity of IBS symptoms was determined by the Composite Pain Score (CPS), administered via Interactive Voice Response System, and the Clinical Global Impressions scale (CGI). The primary outcome was treatment response defined as ≥ 25% reduction in CPS from randomization to end of treatment. A post hoc analysis (multivariate logistic regression) was done to evaluate whether a history of depressive and/or anxiety disorder was associated with response to medication. Results: Baseline demographic and clinical characteristics (CPS, BDI, BAI, PSS, CGI scores) were similar between groups (history of depressive/anxiety disorder vs. no history). In multivariate logistic regression analysis, treatment response was not predicted by history of depressive and/or anxiety disorder (OR = 0.58, CI = 0.29 to 1.68, p = .32) or drug status (paroxetine CR vs. placebo) (OR = 1.26, CI = 0.68 to 3.21, p = .19). Drug status was significantly associated with the secondary outcome variable of treatment response

  6. Autosomal Dominant Alzheimer Disease: A Unique Resource to Study CSF Biomarker Changes in Preclinical AD

    PubMed Central

    Schindler, Suzanne Elizabeth; Fagan, Anne M.

    2015-01-01

    Our understanding of the pathogenesis of Alzheimer disease (AD) has been greatly influenced by investigation of rare families with autosomal dominant mutations that cause early onset AD. Mutations in the genes coding for amyloid precursor protein (APP), presenilin 1 (PSEN-1), and presenilin 2 (PSEN-2) cause over-production of the amyloid-β peptide (Aβ) leading to early deposition of Aβ in the brain, which in turn is hypothesized to initiate a cascade of processes, resulting in neuronal death, cognitive decline, and eventual dementia. Studies of cerebrospinal fluid (CSF) from individuals with the common form of AD, late-onset AD (LOAD), have revealed that low CSF Aβ42 and high CSF tau are associated with AD brain pathology. Herein, we review the literature on CSF biomarkers in autosomal dominant AD (ADAD), which has contributed to a detailed road map of AD pathogenesis, especially during the preclinical period, prior to the appearance of any cognitive symptoms. Current drug trials are also taking advantage of the unique characteristics of ADAD and utilizing CSF biomarkers to accelerate development of effective therapies for AD. PMID:26175713

  7. Treatment response in relation to subthreshold bipolarity in patients with major depressive disorder receiving antidepressant monotherapy: a post hoc data analysis (KOMDD study)

    PubMed Central

    Park, Young-Min; Lee, Bun-Hee

    2016-01-01

    Background The aim of this observational study was to determine whether subthreshold bipolarity affects treatment response and remission in patients with major depressive disorder receiving antidepressant (AD) monotherapy over a 6-month follow-up period. Methods Seventy-eight patients with major depressive disorder were stratified into two subgroups according to the presence of subthreshold bipolarity, identified using the Korean version of the Mood Disorder Questionnaire (K-MDQ), which classifies patients as positive for a screening of bipolarity based on the cutoff for the total K-MDQ score (ie, 7 points). They received AD monotherapy such as escitalopram, sertraline, paroxetine, or tianeptine for 6 months. The Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Scale, and Beck Scale for Suicide Ideation were applied at baseline, 1 week, 3 weeks, 2 months, 3 months, and 6 months. Results The mean HAMD, BDI, and Beck Scale for Suicide Ideation scores were higher in the bipolarity group than in the nonbipolarity group at 3 weeks. The mean BDI score was also higher in the bipolarity group than in the nonbipolarity group at 6 months. Evaluation of the ratio of improvement for each scale revealed different patterns of percentage changes between the two groups over the 6-month follow-up period. Furthermore, the response and remission rates (as assessed using BDI and HAMD scores) were higher in the nonbipolarity group than in the bipolarity group, with the exception of HAMD scores at the 3-week follow-up time point. Conclusion The findings of this study showed that depressed patients with bipolarity had a worse response to AD monotherapy than did those without bipolarity. PMID:27274258

  8. 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

  9. A Value-Added Study of Teacher Spillover Effects across Four Core Subjects in Middle Schools

    ERIC Educational Resources Information Center

    Yuan, Kun

    2015-01-01

    This study examined the existence, magnitude, and impact of teacher spillover effects (TSEs) across teachers of four subject areas (i.e., mathematics, English language arts [ELA], science, and social studies) on student achievement in each of the four subjects at the middle school level. The author conducted a series of value-added (VA) analyses,…

  10. 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. PMID:26405999

  11. Comparison of efficacy and safety of two starting insulin regimens in non-Asian, Asian Indian, and East Asian patients with type 2 diabetes: a post hoc analysis of the PARADIGM study

    PubMed Central

    Ji, Linong; Min, Kyung Wan; Oliveira, Juliana; Lew, Thomas; Duan, Ran

    2016-01-01

    Objective The objective of this study was to explore the efficacy and safety of insulin lispro mix 25 (25% insulin lispro and 75% insulin lispro protamine suspension [LM25]) or insulin glargine plus insulin lispro (G+L) in insulin-naïve patients with type 2 diabetes from different racial/ethnic groups. Methods Three subgroups from the PARADIGM study were analyzed post hoc: non-Asian (n=130), Asian Indian (n=106), and East Asian (n=89). Results All subgroups recorded glycated hemoglobin (HbA1c) reductions: non-Asian (LM25, −2.07%; G+L, −2.05%), Asian Indian (LM25, −1.75%; G+L, −1.60%), and East Asian (LM25, −2.03%; G+L, −1.76%); end point HbA1c values were higher in Asian Indians and East Asians than in non-Asians. Fewer Asian Indians (LM25, 43.2%; G+L, 29.2%) and East Asians (LM25, 37.5%; G+L, 36.1%) reached HbA1c <7% versus non-Asians (LM25, 51.7%; G+L, 48.1%); differences were not significant (P=0.12 and P=0.06, respectively). The mean total daily insulin dose (U/kg) for non-Asians was 0.67 (LM25) and 0.61 (G+L), for Asian Indians was 0.91 (LM25) and 0.90 (G+L), and for East Asians was 0.53 (LM25) and 0.59 (G+L). The ratio of mealtime to total insulin dose in the G+L arm for non-Asians was 0.19±0.23, for Asian Indians was 0.33±0.25, and for East Asians was 0.34±0.27. Overall incidence (%) of hypoglycemia in non-Asians was 94.1 (LM25) and 91.8 (G+L), in Asian Indians was 90.4 (LM25) and 88.5 (G+L), and in East Asians was 69.8 (LM25) and 77.3 (G+L). Conclusion Asian Indians showed least improvement in glycemic HbA1c reduction despite greater insulin use. East Asians and non-Asians achieved similar HbA1c reduction in the LM25 arm with a lower rate of hypoglycemia. Asians required more mealtime insulin coverage than non-Asians. This study added important insight into the effect of ethnicity on insulin treatment outcomes in patients with type 2 diabetes. PMID:27563254

  12. Value Added: A Case Study in the Mismatch between Education Research and Policy

    ERIC Educational Resources Information Center

    Raudenbush, Stephen W.

    2015-01-01

    Recent studies on value added research indicates that, by using data from student perceptions, classroom observations, and test score growth, one can obtain credible evidence of the relative effectiveness of a set of teachers who teach similar children under similar conditions. Recent careful research on school effects indicates that committed…

  13. Preclinical safety, pharmacokinetics, pharmacodynamics, and biodistribution studies with Ad35K++ protein: a novel rituximab cotherapeutic

    PubMed Central

    Richter, Maximilian; Yumul, Roma; Saydaminova, Kamola; Wang, Hongjie; Gough, Michael; Baldessari, Audrey; Cattaneo, Roberto; Lee, Frank; Wang, Chung-Huei Katherine; Jang, Haishan; Astier, Anne; Gopal, Ajay; Carter, Darrick; Lieber, André

    2016-01-01

    Rituximab is a mouse/human chimeric monoclonal antibody targeted toward CD20. It is efficient as first-line therapy of CD20-positive B-cell malignancies. However, a large fraction of treated patients relapse with rituximab-resistant disease. So far, only modest progress has been made in treatment options for rituximab refractory patients. One of the mechanisms for rituximab resistance involves the upregulation of CD46, which is a key cell surface protein that blocks the activation of complement. We have recently developed a technology that depletes CD46 from the cell surface and thereby sensitizes tumor cells to complement-dependent cytotoxicity. This technology is based on a small recombinant protein, Ad35K++ that binds with high affinity to CD46. In preliminary studies using a 6 × histidinyl tagged protein, we had demonstrated that intravenous Ad35K++ injection in combination with rituximab was safe and increased rituximab-mediated killing of CD20-positive target cells in mice and nonhuman primates (NHPs). The presence of the tag, while allowing for easy purification by Ni-NTA chromatography, has the potential to increase the immunogenicity of the recombinant protein. For clinical application, we therefore developed an Ad35K++ protein without His-tag. In the present study, we performed preclinical studies in two animal species (mice and NHPs) with this protein demonstrating its safety and efficacy. These studies estimated the Ad35K++ dose range and treatment regimen to be used in patients. Furthermore, we showed that intravenous Ad35K++ injection triggers the shedding of the CD46 extracellular domain in xenograft mouse tumor models and in macaques. Shed serum CD46 can be measured in the serum and can potentially be used as a pharmacodynamic marker for monitoring Ad35K++ activity in patient undergoing treatment with this agent. These studies create the basis for an investigational new drug application for the use of Ad35K++ in combination with rituximab in the

  14. Preclinical safety, pharmacokinetics, pharmacodynamics, and biodistribution studies with Ad35K++ protein: a novel rituximab cotherapeutic.

    PubMed

    Richter, Maximilian; Yumul, Roma; Saydaminova, Kamola; Wang, Hongjie; Gough, Michael; Baldessari, Audrey; Cattaneo, Roberto; Lee, Frank; Wang, Chung-Huei Katherine; Jang, Haishan; Astier, Anne; Gopal, Ajay; Carter, Darrick; Lieber, André

    2016-01-01

    Rituximab is a mouse/human chimeric monoclonal antibody targeted toward CD20. It is efficient as first-line therapy of CD20-positive B-cell malignancies. However, a large fraction of treated patients relapse with rituximab-resistant disease. So far, only modest progress has been made in treatment options for rituximab refractory patients. One of the mechanisms for rituximab resistance involves the upregulation of CD46, which is a key cell surface protein that blocks the activation of complement. We have recently developed a technology that depletes CD46 from the cell surface and thereby sensitizes tumor cells to complement-dependent cytotoxicity. This technology is based on a small recombinant protein, Ad35K++ that binds with high affinity to CD46. In preliminary studies using a 6 × histidinyl tagged protein, we had demonstrated that intravenous Ad35K++ injection in combination with rituximab was safe and increased rituximab-mediated killing of CD20-positive target cells in mice and nonhuman primates (NHPs). The presence of the tag, while allowing for easy purification by Ni-NTA chromatography, has the potential to increase the immunogenicity of the recombinant protein. For clinical application, we therefore developed an Ad35K++ protein without His-tag. In the present study, we performed preclinical studies in two animal species (mice and NHPs) with this protein demonstrating its safety and efficacy. These studies estimated the Ad35K++ dose range and treatment regimen to be used in patients. Furthermore, we showed that intravenous Ad35K++ injection triggers the shedding of the CD46 extracellular domain in xenograft mouse tumor models and in macaques. Shed serum CD46 can be measured in the serum and can potentially be used as a pharmacodynamic marker for monitoring Ad35K++ activity in patient undergoing treatment with this agent. These studies create the basis for an investigational new drug application for the use of Ad35K++ in combination with rituximab in the

  15. Brain areas involved in the acupuncture treatment of AD model rats: a PET study

    PubMed Central

    2014-01-01

    Background Acupuncture may effectively treat certain symptoms of Alzheimer’s disease (AD). Although several studies have used functional brain imaging to investigate the mechanisms of acupuncture treatment on AD, these mechanisms are still poorly understood. We therefore further explored the mechanism by which needling at ST36 may have a therapeutic effect in a rat AD model. Methods A total of 80 healthy Wistar rats were divided into healthy control (n = 15) and pre-model (n = 65) groups. After inducing AD-like disease, a total of 45 AD model rats were randomly divided into three groups: the model group (n = 15), the sham-point group (n = 15), and the ST36 group (n = 15). The above three groups underwent PET scanning. PET images were processed with SPM2. Results The brain areas that were activated in the sham-point group relative to the model group were primarily centred on the bilateral limbic system, the right frontal lobe, and the striatum, whereas the activated areas in the ST36 group were primarily centred on the bilateral limbic system (pyriform cortex), the bilateral temporal lobe (olfactory cortex), the right amygdala and the right hippocampus. Compared with the sham-point group, the ST36 group showed greater activation in the bilateral amygdalae and the left temporal lobe. Conclusion We concluded that needling at a sham point or ST36 can increase blood perfusion and glycol metabolism in certain brain areas, and thus may have a positive influence on the cognition of AD patients. PMID:24886495

  16. Changes in Gait with Anteriorly Added Mass: A Pregnancy Simulation Study.

    PubMed

    Ogamba, Maureen I; Loverro, Kari L; Laudicina, Natalie M; Gill, Simone V; Lewis, Cara L

    2016-08-01

    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 3 load conditions: sac-only condition, 10-lb condition (4.535 kg added anteriorly), and 20-lb 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. In addition, 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

  17. Balance, executive functions and falls in elderly with Alzheimer's disease (AD): a longitudinal study.

    PubMed

    Pedroso, Renata Valle; Coelho, Flávia Gomes de Melo; Santos-Galduróz, Ruth Ferreira; Costa, José Luiz Riani; Gobbi, Sebastião; Stella, Florindo

    2012-01-01

    Elderly individuals with AD are more susceptible to falls, which might be associated with decrements in their executive functions and balance, among other things. We aimed to analyze the effects of a program of dual task physical activity on falls, executive functions and balance of elderly individuals with AD. We studied 21 elderly with probable AD, allocated to two groups: the training group (TG), with 10 elderly who participated in a program of dual task physical activity; and the control group (CG), with 11 elderly who were not engaged in regular practice of physical activity. The Clock Drawing Test (CDT) and the Frontal Assessment Battery (FAB) were used in the assessment of the executive functions, while the Berg Balance Scale (BBS) and the Timed Up-and-Go (TUG)-test evaluated balance. The number of falls was obtained by means of a questionnaire. We observed a better performance of the TG as regards balance and executive functions. Moreover, the lower the number of steps in the TUG scale, the higher the scores in the CDT, and in the FAB. The practice of regular physical activity with dual task seems to have contributed to the maintenance and improvement of the motor and cognitive functions of the elderly with AD. PMID:21774999

  18. Study of micro piezoelectric vibration generator with added mass and capacitance suitable for broadband vibration

    SciTech Connect

    He, Qing Mao, Xinhua Chu, Dongliang

    2015-07-15

    This study proposes an optimized frequency adjustment method that uses a micro-cantilever beam-based piezoelectric vibration generator based on a combination of added mass and capacitance. The most important concept of the proposed method is that the frequency adjustment process is divided into two steps: the first is a rough adjustment step that changes the size of the mass added at the end of cantilever to adjust the frequency in a large-scale and discontinuous manner; the second step is a continuous but short-range frequency adjustment via the adjustable added capacitance. Experimental results show that when the initial natural frequency of a micro piezoelectric vibration generator is 69.8 Hz, then this natural frequency can be adjusted to any value in the range from 54.2 Hz to 42.1 Hz using the combination of the added mass and the capacitance. This method simply and effectively matches a piezoelectric vibration generator’s natural frequency to the vibration source frequency.

  19. Patient Background Factors Affecting the Therapeutic Outcomes in Response to Eszopiclone in Adult Patients with Chronic Insomnia: A Post Hoc Analysis of a Double-Blind Phase III Study in Japan

    PubMed Central

    Inoue, Yuichi; Kamijo, Atsushi; Nagai, Reiko

    2015-01-01

    Study Objective: To identify whether baseline demographic factors or subjective sleep variables are associated with the outcomes following treatment with eszopiclone using data from a recent randomized controlled trial of 78 Japanese subjects with insomnia who were treated with 2 mg eszopiclone per day. Methods: We performed a post hoc analysis of factors including sleep latency (SL), wake time after sleep onset (WASO) (both assessed via sleep diaries), and several demographic variables. Subjects with a SL or WASO > 30 min at baseline and with evaluable SL/WASO data at Week 4 were included in SL and WASO remitter analyses, respectively; those with a SL or WASO ≤ 30 min at Week 4 were defined as SL or WASO remitters, respectively. Threshold baseline SL and WASO values for identification of remitters were determined. Results: No relationships between subjectively assessed therapeutic outcomes and demographic factors were identified. Patients with shorter SL and lower WASO values at baseline showed better outcomes following treatment with eszopiclone in terms of SL and WASO changes, respectively. Baseline SL of 75 min and baseline WASO of 80 min were selected as arbitrary cutoff values for determination of SL and WASO remitters/non-remitters, respectively. Conclusions: These findings may help clinicians to predict their patients' outcomes in response to standard doses of eszopiclone in clinical practice. Citation: Inoue Y, Kamijo A, Nagai R. Patient background factors affecting the therapeutic outcomes in response to eszopiclone in adult patients with chronic insomnia: a post hoc analysis of a double-blind phase III study in Japan. J Clin Sleep Med 2015;11(10):1171–1178. PMID:26094929

  20. Effusion of hydrophobic organic compounds (HOCs) from fog droplets

    SciTech Connect

    Lee, W.M.; Tsay, C.

    1998-12-31

    In this study, the effects of surface-active substances, pH and salt on the effusion of HOCs from droplets were investigated. An HOCs-effusion reactor was established for experiments. N-octane was used for the HOCs and Sodium Dodecyl Sulfate (SDS) was selected as the surface-active substance. A correction factor to mass exchange constant, defined as the deviation of exchange constant of n-octane in fog phase from that in planar aqueous phase was used to quantify the effects of surface-active substance, pH, and salt concentration on the effusion rate of HOCs from fog droplets by a modified double-layer diffusion model. The results showed that surface-active substances, SDS cab decrease the effusion rate of n-octane from fog droplets by about 40%--62% and the values of were in the range of 0.382 to 0.609. The salt, sodium chloride, at the concentration of 1.00 {times} 10{sup {minus}3} [M] can further decrease the mass transfer rate of n-octane from fog droplets because the values changed from 0.590 to 0.368, so that the effusion rate was further decrease by salt. When pH values were between 5.60 and 2.00, values varied from 0.609 to 0.367 at SDS concentration of 1.00 x 10{sup 3}[M]. This indicated that the effusion rate of HOCs from fog droplets decreased with decreasing pH value.

  1. Slowing progression of early stages of AD with alternative therapies: a feasibility study.

    PubMed

    Lu, Der-Fa; Hart, Laura K; Lutgendorf, Susan K; Oh, Hyunkyoung; Schilling, Margo

    2013-01-01

    This pilot study identified the feasibility and efficacy of the effect of combining healing touch (HT) and body talk cortices (BTC) on the progression of Alzheimer's disease (AD). Both HT and BTC elicit the relaxation response and support cognitive function from two different perspectives. A two-group, repeated measures design was used. Subjects (n = 22), 65 or older with early stage (less than four) AD, residing in the community (n = 2) or in care agencies (n = 20), were assigned to either the HT-BTC group (n = 12) or the control group (n = 10) randomized by residence. The treatment group received, 6 months of weekly HT and performed the BTC technique daily. The usual medical regimen for all subjects was continued. The control group had no additional interventions. Both groups were assessed at baseline, 3 and 6 months. The groups did not differ significantly at baseline on cognitive reserve, age, gender, and ethnicity, nor on the outcome variables (cognitive function, mood, & depression). Adherence (76%) to the BTC protocol, the major feasibility problem, related to memory deficits. Significant interactions occurred regarding cognitive function and mood. Significant improvements in cognitive function (p = .008), mood (p = .001), and depression (p = .028) were observed in the treatment group which is not the usual course of AD. A decline in cognitive function occurred in the control group typical of AD's usual course. Although the number of subjects in this pilot study was small, and there were feasibility challenges with recruitment and adherence, important trends were noted suggesting areas for future study. PMID:23972540

  2. Feasibility study for the assessment of the exposed dose with TENORM added in consumer products.

    PubMed

    Yoo, Do Hyeon; Lee, Hyun Cheol; Shin, Wook-Geun; Ha, Wi-Ho; Yoo, Jae Ryong; Yoon, Seok-Won; Lee, Jiyon; Choi, Won-Chul; Min, Chul Hee

    2015-11-01

    Consumer products including naturally occurring radioactive material have been distributed widely in human life. The potential hazard of the excessively added technically enhanced naturally occurring radioactive material (TENORM) in consumer products should be assessed. The aim of this study is to evaluate the organ equivalent dose and the annual effective dose with the usage of the TENORM added in paints. The activities of gammas emitted from natural radionuclides in the five types of paints were measured with the high-purity germanium detector, and the annual effective dose was assessed with the computational human phantom and the Monte Carlo method. The results show that uranium and thorium series were mainly measured over the five paints. Based on the exposure scenario of the paints in the room, the highest effective dose was evaluated as <1 mSv y(-1) of the public dose limit. PMID:25956783

  3. Genetic Studies of Quantitative MCI and AD Phenotypes in ADNI: Progress, Opportunities, and Plans

    PubMed Central

    Saykin, Andrew J.; Shen, Li; Yao, Xiaohui; Kim, Sungeun; Nho, Kwangsik; Risacher, Shannon L.; Ramanan, Vijay K.; Foroud, Tatiana M.; Faber, Kelly M.; Sarwar, Nadeem; Munsie, Leanne M.; Hu, Xiaolan; Soares, Holly D.; Potkin, Steven G.; Thompson, Paul M.; Kauwe, John S.K.; Kaddurah-Daouk, Rima; Green, Robert C.; Toga, Arthur W.; Weiner, Michael W.

    2015-01-01

    INTRODUCTION Genetic data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) has been crucial in advancing the understanding of AD pathophysiology. Here we provide an update on sample collection, scientific progress and opportunities, conceptual issues, and future plans. METHODS Lymphoblastoid cell lines and DNA and RNA samples from blood have been collected and banked, and data and biosamples have been widely disseminated. To date, APOE genotyping, genome-wide association study (GWAS), and whole exome and whole genome sequencing (WES, WGS) data have been obtained and disseminated. RESULTS ADNI genetic data have been downloaded thousands of times and over 300 publications have resulted, including reports of large scale GWAS by consortia to which ADNI contributed. Many of the first applications of quantitative endophenotype association studies employed ADNI data, including some of the earliest GWAS and pathway-based studies of biospecimen and imaging biomarkers, as well as memory and other clinical/cognitive variables. Other contributions include some of the first WES and WGS data sets and reports in healthy controls, MCI, and AD. DISCUSSION Numerous genetic susceptibility and protective markers for AD and disease biomarkers have been identified and replicated using ADNI data, and have heavily implicated immune, mitochondrial, cell cycle/fate, and other biological processes. Early sequencing studies suggest that rare and structural variants are likely to account for significant additional phenotypic variation. Longitudinal analyses of transcriptomic, proteomic, metabolomic, and epigenomic changes will also further elucidate dynamic processes underlying preclinical and prodromal stages of disease. Integration of this unique collection of multi-omics data within a systems biology framework will help to separate truly informative markers of early disease mechanisms and potential novel therapeutic targets from the vast background of less relevant biological

  4. DIS in AdS

    NASA Astrophysics Data System (ADS)

    Albacete, Javier L.; Kovchegov, Yuri V.; Taliotis, Anastasios

    2009-03-01

    We calculate the total cross section for the scattering of a quark-anti-quark dipole on a large nucleus at high energy for a strongly coupled N = 4 super Yang-Mills theory using AdS/CFT correspondence. We model the nucleus by a metric of a shock wave in AdS5. We then calculate the expectation value of the Wilson loop (the dipole) by finding the extrema of the Nambu-Goto action for an open string attached to the quark and antiquark lines of the loop in the background of an AdS5 shock wave. We find two physically meaningful extremal string configurations. For both solutions we obtain the forward scattering amplitude N for the quark dipole-nucleus scattering. We study the onset of unitarity with increasing center-of-mass energy and transverse size of the dipole: we observe that for both solutions the saturation scale Qs is independent of energy/Bjorken-x and depends on the atomic number of the nucleus as Qs˜A1/3. Finally we observe that while one of the solutions we found corresponds to the pomeron intercept of αP = 2 found earlier in the literature, when extended to higher energy or larger dipole sizes it violates the black disk limit. The other solution we found respects the black disk limit and yields the pomeron intercept of αP = 1.5. We thus conjecture that the right pomeron intercept in gauge theories at strong coupling may be αP = 1.5.

  5. Study of the star catalogue (epoch AD 1396.0) recorded in ancient Korean astronomical almanac

    NASA Astrophysics Data System (ADS)

    Jeon, Junhyeok; Lee, Yong Bok; Lee, Yong-Sam

    2015-11-01

    The study of old star catalogues provides important astrometric data. Most of the researches based on the old star catalogues were manuscript published in Europe and from Arabic/Islam. However, the old star catalogues published in East Asia did not get attention. Therefore, among the East Asian star catalogues we focus on a particular catalogue recorded in a Korean almanac. Its catalogue contains 277 stars that are positioned in a region within 10° of the ecliptic plane. The stars in the catalogue were identified using the modern Hipparcos catalogue. We identified 274 among 277 stars, which is a rate of 98.9 per cent. The catalogue records the epoch of the stars' positions as AD 1396.0. However, by using all of the identified stars we found that the initial epoch of the catalogue is AD 1363.1 ± 3.2. In conclusion, the star catalogue was compiled and edited from various older star catalogues. We assume a correlation with the Almagest by Ptolemaios. This study presents newly analysed results from the historically important astronomical data discovered in East Asia. Therefore, this star catalogue will become important data for comparison with the star catalogues published in Europe and from Arabic/Islam.

  6. Study on anisotropic silicon etching characteristics in various surfactant-added tetramethyl ammonium hydroxide water solutions

    NASA Astrophysics Data System (ADS)

    Yang, Chii-Rong; Yang, Cheng-Hao; Chen, Po-Ying

    2005-11-01

    Three ion-typed surfactants, including anionic sodium dihexyl sulfosuccinate (SDSS), cationic ammonium salt of poly(ethylene glycol) (ASPEG) and non-ionic poly(ethylene glycol) (PEG), were added to 10 wt% tetramethyl ammonium hydroxide water (TMAHW) solutions to evaluate the silicon anisotropic etching properties of the (1 0 0) silicon plane without agitation and no isopropyl alcohol (IPA) additive. The results indicate that the wetting capacity of the etchants cause the efficacies of the etchants on the roughness reduction to follow the order cationic ASPEG, non-ionic PEG, pure solution and anionic SDSS in TMAHW solutions, especially at high etching temperatures. Moreover, the chemical activities of the etchants cause the efficacies of the etchants on the etching rates to follow the order anionic SDSS, pure solution, cationic ASPEG and non-ionic PEG in TMAHW solutions at a given etching temperature. The cationic ASPEG has a reasonable etching rate of 0.7 µm min-1 and the lowest surface roughness of 4 nm in TMAHW solutions at an etching temperature of 100 °C. ASPEG and PEG in TMAHW solutions markedly affect aluminum passivation. The undercutting of the convex corners in PEG-added TMAHW solutions can be drastically reduced without using corner compensation; the undercutting ratio obtained using a PEG surfactant is about 45% lower than that obtained in pure TMAHW solution. This finding reveals that non-ionic PEG should be added to TMAHW solutions when accurate profiles are required without extremely deep etching. This study also demonstrated that non-ionic PEG is more appropriate than IPA for anisotropic silicon TMAHW etching.

  7. An overview of the LASER-AD study: a longitudinal epidemiological study of people with Alzheimer's disease.

    PubMed

    Hoe, Juanita; Cooper, Claudia; Livingston, Gill

    2013-12-01

    Research into the epidemiological, clinical characteristics and economic impact of dementia is critical to increase understanding and better inform care and policy, and empower people with Alzheimer's disease (AD) and their families to make preparations and timely decisions about accommodation, care and treatment. The LASER-AD longitudinal study of people with AD and their carers has contributed to our understanding of the progression, characteristics and costs of the disease, and to developing tools that help detect dementia earlier, and screen and identify problems experienced by carers. Our work on quality of life shows that even those with severe dementia can report this meaningfully, although family proxy ratings of quality of life do not necessarily mirror the views of the individual. Despite the impact of the disease process, people with AD experience well-being in adversity and still live fulfilling lives. The study highlights the high prevalence and severity of neuropsychiatric symptoms, carer anxiety, depression and abusive behaviour. It informs future directions for possible interventions, in particular the central role of carer coping strategies in predicting carer mental illness. Current research is building on our findings, which have also been used to inform national and international plans for managing people with dementia and their carers. PMID:24423220

  8. Polarised black holes in AdS

    NASA Astrophysics Data System (ADS)

    Costa, Miguel S.; Greenspan, Lauren; Oliveira, Miguel; Penedones, João; Santos, Jorge E.

    2016-06-01

    We consider solutions in Einstein-Maxwell theory with a negative cosmological constant that asymptote to global AdS 4 with conformal boundary {S}2× {{{R}}}t. At the sphere at infinity we turn on a space-dependent electrostatic potential, which does not destroy the asymptotic AdS behaviour. For simplicity we focus on the case of a dipolar electrostatic potential. We find two new geometries: (i) an AdS soliton that includes the full backreaction of the electric field on the AdS geometry; (ii) a polarised neutral black hole that is deformed by the electric field, accumulating opposite charges in each hemisphere. For both geometries we study boundary data such as the charge density and the stress tensor. For the black hole we also study the horizon charge density and area, and further verify a Smarr formula. Then we consider this system at finite temperature and compute the Gibbs free energy for both AdS soliton and black hole phases. The corresponding phase diagram generalizes the Hawking-Page phase transition. The AdS soliton dominates the low temperature phase and the black hole the high temperature phase, with a critical temperature that decreases as the external electric field increases. Finally, we consider the simple case of a free charged scalar field on {S}2× {{{R}}}t with conformal coupling. For a field in the SU(N ) adjoint representation we compare the phase diagram with the above gravitational system.

  9. Looking for added value in Australian downscaling for climate change studies

    NASA Astrophysics Data System (ADS)

    Grose, Michael

    2015-04-01

    Downscaling gives the prospect of added value in the regional pattern and temporal nature of rainfall change with a warmer climate. However, such value is not guaranteed and the use of downscaling can raise rather than diminish uncertainties. Validation of downscaling methods tends to focus on the ability to simulate current climate statistics, rather than the robustness of simulated future climate change. Here we compare the future climate change signal in average rainfall from various dynamical and statistical downscaling outputs used for all of Australia and in regional climate change studies over smaller domains. We show that downscaling can generate different regional patterns of projected change compared to the global climate models used as input, indicating the potential for added value in projections. These differences often make physical sense in regions of complex topography such as in southeast Australia, the eastern seaboard and Tasmania. However, results from different methods are not always consistent. In addition, downscaling can produce projected changes that are not clearly related to finer resolution and are difficult to interpret. In some cases, each downscaling method gives a different range of results and different messages about projected rainfall change for a region. This shows that downscaling has the potential to add value to projections, but also brings the potential for uncertain or contradictory messages. We conclude that each method has strengths and weaknesses, and these should be clearly communicated.

  10. The 365 AD tsunami imprint on the coasts of southwestern Crete - Sougia and Palaiochora case studies

    NASA Astrophysics Data System (ADS)

    Werner, Vera; Baika, Kalliopi; Tzigounaki, Anastasia; Tsigkou, Aggeliki; Fischer, Peter; Reicherter, Klaus; Papanikolaou, Ioannis; Vött, Andreas

    2016-04-01

    The southwestern coast of Crete, one of the most seismically active regions in Europe, is supposed to have been uplifted by up to 9 m during the mega-earthquake that struck the eastern Mediterranean world on July 21, 365 AD. An associated tsunami event is known to have caused thousands of fatalities and destroyed many coastal settlements and infrastructure between the Levante in the east and the Adriatic Sea in the northwest. Since this event, the entire southwestern coast of Crete has experienced strong erosion so that near-coast geological archives showing relevant Holocene sedimentary records are rare. So far, distinct palaeotsunami fingerprints from coastal archives in this region were unknown. A multi-proxy study including sedimentological, geochemical, geochronological and microfaunal methods was conducted at Sougia, within an ancient harbour basin, and around the promontory of Palaiochora. Detailed multi-electrode geoelectrical studies and several near-coast vibracores helped to detect promising local sedimentary archives. In addition, prominent elevated shorelines, evidenced by notches and algal rims, were measured with DGPS. Sedimentary archives found at Sougia and Palaiochora revealed distinct sedimentological, geochemical and geomorphological traces of high-energy inundation from the marine side. At Sougia, we found a sheet of allochthonous marine sand, partly cemented, intersecting silt-dominated harbour deposits. At Palaiochora, we found high-energy channels eroded in the local bedrock and filled with marine-borne sand and gravel on top of the Palaiochora isthmus, today some 400 m inland. Based on geochemical and microfaunal fingerprints and on sedimentary features, high-energy deposits are interpreted as tsunamites. 14C-AMS- and OSL dating approaches revealed that the tsunami sequences from both Sougia and Palaiochora were deposited during the 365 AD tsunami event. We also present and discuss conceptual tsunami landfall scenarios for both study sites.

  11. 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.

  12. A nonhuman primate toxicology and immunogenicity study evaluating aerosol delivery of AERAS-402/Ad35 vaccine

    PubMed Central

    Hokey, David A; Wachholder, Robert; Darrah, Patricia A; Bolton, Diane L; Barouch, Dan H; Hill, Krystal; Dheenadhayalan, Veerabadran; Schwander, Stephan; Godin, C Steven; Douoguih, Macaya; Pau, Maria Grazia; Seder, Robert A; Roederer, Mario; Sadoff, Jerald C; Sizemore, Donata

    2014-01-01

    Bacille Calmette-Guérin (BCG), the only licensed vaccine for the prevention of tuberculosis (TB), provides only limited protection against certain forms of Mycobacterium tuberculosis (Mtb) infection. While infection with Mtb can be treated with antibiotics, the therapy is expensive, toxic, and requires several months for treatment. In addition, the emergence of drug resistant strains limits the impact of antibiotics and underlines the importance of developing a more effective vaccine to control this disease. Given that pulmonary TB is the most common form of the disease, a vaccine capable of inducing lung-resident immunity may be advantageous for combating this infection. New advances in pulmonary delivery make this route of vaccination feasible and affordable. Here, we evaluate the safety and immunogenicity of an aerosolized Ad35-based vaccine, AERAS-402, delivered to the lungs in nonhuman primates as part of a GLP acute and chronic toxicology and safety study. In this study, animals received three high doses (1 x 1011 vp) of AERAS-402 by inhalation via a nebulizer at 1-week intervals. Aerosol delivery of AERAS-402 resulted in an increase in relative lung weights as well as microscopic findings in the lungs, mediastinal lymph nodes, bronchus-associated lymphatic tissue, and the naso-oropharynx that were consistent with the induction of an immune response during the acute phase. These findings resolved by the chronic phase and were considered to be non-adverse. Furthermore, we observed transient vaccine-specific immune responses in the peripheral blood as well as sustained high-level polyfunctional CD4+ and CD8+ T cell responses in the bronchoalveolar lavage fluid of vaccinated nonhuman primates. The data suggest that pulmonary delivery of Ad35-based vaccines can be safe and can induce potent lung-resident immunity. PMID:25424923

  13. Migraine and triggers: Post hoc ergo propter hoc?

    PubMed Central

    Hoffmann, Jan; Recober, Ana

    2013-01-01

    The influence of environmental factors on the clinical manifestation of migraine has been a matter of extensive debate over the past decades. Migraineurs commonly report foods, alcohol, meteorologic or atmospheric changes, exposure to light, sounds, or odors, as factors that trigger or aggravate their migraine attacks. In the same way, physicians frequently follow this belief in their recommendations in how migraineurs may reduce their attack frequency, especially with regard to the consumption of certain food components. Interestingly, despite being such a common belief, most of the clinical studies have shown conflicting results. The aim of the review is to critically analyze clinical and pathophysiological facts that support or refute a correlation between certain environmental stimuli and the occurrence of migraine attacks. Given the substantial discrepancy between patients' reports and objective clinical data, the methodological difficulties of investigating the link between environmental factors and migraine are highlighted. PMID:23996725

  14. Value-Added Dairy Products from Grass-Based Dairy Farms: A Case Study in Vermont

    ERIC Educational Resources Information Center

    Wang, Qingbin; Parsons, Robert; Colby, Jennifer; Castle, Jeffrey

    2016-01-01

    On-farm processing of value-added dairy products can be a way for small dairy farms to diversify production and increase revenue. This article examines characteristics of three groups of Vermont farmers who have grass-based dairy farms--those producing value-added dairy products, those interested in such products, and those not interested in such…

  15. Old Words, New Meanings: A Study of Trends in Science Librarian Job Ads

    ERIC Educational Resources Information Center

    Bychowski, Brenna K. H.; Caffrey, Carolyn M.; Costa, Mia C.; Moore, Angela D.; Sudhakaran, Jessamyn; Zhang, Yuening

    2010-01-01

    Job ads are supposed to provide careful descriptions of the positions being advertised. Based on this premise, an analysis of job ads over time should reveal emerging trends and changes in a profession. The existing literature on science librarianship emphasizes that there are fluctuations in the demand for subject expertise and technology skills…

  16. Mapping of Streptococcus faecalis plasmids pAD1 and pAD2 and studies relating to transposition of Tn917.

    PubMed Central

    Clewell, D B; Tomich, P K; Gawron-Burke, M C; Franke, A E; Yagi, Y; An, F Y

    1982-01-01

    Plasmids pAD1 (37.8 megadaltons) and pAD2 (17.1 megadaltons) of Streptococcus faecalis strain DS16 have been mapped with restriction enzymes. The location of a hemolysin-bacteriocin determinant on the conjugative pAD1 plasmid was derived from analyses of transposon insertions. Electron microscope and hybridization analyses located Tn917(Em) and the streptomycin (Sm) and kanamycin (Km) resistance determinants on the nonconjugative pAD2 plasmid. It was shown previously that the erythromycin (Em) resistance associated with Tn917 is inducible and that transposition from pAD2 to pAD1 is also stimulated by exposure of cells to low concentrations of Em. Here we show that inducing concentrations of Em also increase the conjugative transfer potential of pAD1; this is possibly related to a mild and short-lived inhibitory stress placed on the cells before full induction of resistance. Selection of Em-resistant transconjugants arising from matings between DS16 and a plasmid-free recipient gave rise to transconjugants which primarily harbor stable pAD1::pAD2 cointegrates. A 30-min exposure of donors to Em (0.5 microgram/ml) before mating resulted in a severalfold increase in the number of such transconjugants. However, a small fraction (e.g., 3 of 40) of these Emr Smr Kmr transconjugants harbored pAD1::Tn917 and pAD2 molecules. Since we believe pAD2 is incapable of being mobilized by pAD1 without being covalently linked, it is likely that transfer in these cases involved cointegrates representing structural intermediates in the transposition of Tn917 from pAD2 to pAD1. It follows that such intermediates probably had two copies of Tn917 and readily resolved after transfer. (These cointegrates are different from the stable cointegrates which were shown to have only a single copy of Tn917; the latter are assumed not to be related to transposition.) Two variants with altered Tn917 transposition properties were derived. One of them transposed at an elevated frequency, whereas the

  17. Predictors of Non-Stabilization during the Combination Therapy of Lithium and Divalproex in Rapid Cycling Bipolar Disorder: A Post-hoc Analysis of Two Studies

    PubMed Central

    Gao, Keming; Kemp, David E.; Wang, Zuowei; Ganocy, Stephen J.; Conroy, Carla; Serrano, Marry Beth; Sajatovic, Martha; Findling, Robert L.; Calabrese, Joseph R.

    2012-01-01

    Objective To study predictors of non–stabilization (i.e., not bimodally stabilized for randomization or not randomized due to premature discontinuation) during open-label treatment with lithium and divalproex in patients with rapid-cycling bipolar disorder (RCBD) with or without comorbid recent substance use disorders (SUDs). Method Data from the open-label phase of two maintenance studies were used. The reasons for non-stabilization were compared between patients with a recent SUD and those without. Predictors for non-stabilization were explored with logistic regression analyses. Results Of 149 patients with recent SUD and 254 without recent SUD enrolled into the open-label acute stabilization phase, 21% and 24% were stabilized and randomized, respectively. Compared to those without recent SUD, patients with recent SUD were more likely to discontinue the study due to non-adherence to the protocol, 53% versus 37% (OR = 1.92) or refractory mania/hypomania, 15% versus 9% (OR = 1.87), but less likely due to refractory depression 16% versus 25% (OR = 0.58) or adverse events, 10% versus 19% (OR = 0.44). A history of recent SUDs, early life verbal abuse, female gender, and late onset of first depressive episode were associated with increased risk for non-stabilization with ORs of 1.85, 1.74, 1.10, and 1.04, respectively. Conclusions During open treatment with lithium and divalproex in patients with RCBD, a recent SUD, a lifetime history of verbal abuse, female gender, and late onset of first depression independently predicted non-stabilization. The non-stabilization for patients with SUD was related to non-adherence and refractory mania/hypomania. PMID:20581798

  18. DIS in AdS

    SciTech Connect

    Albacete, Javier L.; Kovchegov, Yuri V.; Taliotis, Anastasios

    2009-03-23

    We calculate the total cross section for the scattering of a quark-anti-quark dipole on a large nucleus at high energy for a strongly coupled N = 4 super Yang-Mills theory using AdS/CFT correspondence. We model the nucleus by a metric of a shock wave in AdS{sub 5}. We then calculate the expectation value of the Wilson loop (the dipole) by finding the extrema of the Nambu-Goto action for an open string attached to the quark and antiquark lines of the loop in the background of an AdS{sub 5} shock wave. We find two physically meaningful extremal string configurations. For both solutions we obtain the forward scattering amplitude N for the quark dipole-nucleus scattering. We study the onset of unitarity with increasing center-of-mass energy and transverse size of the dipole: we observe that for both solutions the saturation scale Q{sub s} is independent of energy/Bjorken-x and depends on the atomic number of the nucleus as Q{sub s}{approx}A{sup 1/3}. Finally we observe that while one of the solutions we found corresponds to the pomeron intercept of {alpha}{sub P} = 2 found earlier in the literature, when extended to higher energy or larger dipole sizes it violates the black disk limit. The other solution we found respects the black disk limit and yields the pomeron intercept of {alpha}{sub P} = 1.5. We thus conjecture that the right pomeron intercept in gauge theories at strong coupling may be {alpha}{sub P} = 1.5.

  19. Post hoc Analysis for Detecting Individual Rare Variant Risk Associations Using Probit Regression Bayesian Variable Selection Methods in Case-Control Sequencing Studies.

    PubMed

    Larson, Nicholas B; McDonnell, Shannon; Albright, Lisa Cannon; Teerlink, Craig; Stanford, Janet; Ostrander, Elaine A; Isaacs, William B; Xu, Jianfeng; Cooney, Kathleen A; Lange, Ethan; Schleutker, Johanna; Carpten, John D; Powell, Isaac; Bailey-Wilson, Joan; Cussenot, Olivier; Cancel-Tassin, Geraldine; Giles, Graham; MacInnis, Robert; Maier, Christiane; Whittemore, Alice S; Hsieh, Chih-Lin; Wiklund, Fredrik; Catolona, William J; Foulkes, William; Mandal, Diptasri; Eeles, Rosalind; Kote-Jarai, Zsofia; Ackerman, Michael J; Olson, Timothy M; Klein, Christopher J; Thibodeau, Stephen N; Schaid, Daniel J

    2016-09-01

    Rare variants (RVs) have been shown to be significant contributors to complex disease risk. By definition, these variants have very low minor allele frequencies and traditional single-marker methods for statistical analysis are underpowered for typical sequencing study sample sizes. Multimarker burden-type approaches attempt to identify aggregation of RVs across case-control status by analyzing relatively small partitions of the genome, such as genes. However, it is generally the case that the aggregative measure would be a mixture of causal and neutral variants, and these omnibus tests do not directly provide any indication of which RVs may be driving a given association. Recently, Bayesian variable selection approaches have been proposed to identify RV associations from a large set of RVs under consideration. Although these approaches have been shown to be powerful at detecting associations at the RV level, there are often computational limitations on the total quantity of RVs under consideration and compromises are necessary for large-scale application. Here, we propose a computationally efficient alternative formulation of this method using a probit regression approach specifically capable of simultaneously analyzing hundreds to thousands of RVs. We evaluate our approach to detect causal variation on simulated data and examine sensitivity and specificity in instances of high RV dimensionality as well as apply it to pathway-level RV analysis results from a prostate cancer (PC) risk case-control sequencing study. Finally, we discuss potential extensions and future directions of this work. PMID:27312771

  20. The Effect of Lowering LDL Cholesterol on Vascular Access Patency: Post Hoc Analysis of the Study of Heart and Renal Protection

    PubMed Central

    Herrington, William; Emberson, Jonathan; Staplin, Natalie; Blackwell, Lisa; Fellström, Bengt; Walker, Robert; Levin, Adeera; Hooi, Lai Seong; Massy, Ziad A.; Tesar, Vladimir; Reith, Christina; Haynes, Richard; Baigent, Colin

    2014-01-01

    Background and objectives Reducing LDL cholesterol (LDL-C) with statin-based therapy reduces the risk of major atherosclerotic events among patients with CKD, including dialysis patients, but the effect of lowering LDL-C on vascular access patency is unclear. Design, setting, participants, & measurements The Study of Heart and Renal Protection (SHARP) randomized patients with CKD to 20 mg simvastatin plus 10 mg ezetimibe daily versus matching placebo. This study aimed to explore the effects of treatment on vascular access occlusive events, defined as any access revision procedure, access thrombosis, removal of an old dialysis access, or formation of new permanent dialysis access. Results Among 2353 SHARP participants who had functioning vascular access at randomization, allocation to simvastatin plus ezetimibe resulted in a 13% proportional reduction in vascular access occlusive events (355 [29.7%] for simvastatin/ezetimibe versus 388 [33.5%] for placebo; risk ratio [RR], 0.87; 95% confidence interval [95% CI], 0.75 to 1.00; P=0.05). There was no evidence that the effects of treatment differed for any of the separate components of this outcome. To test the hypothesis raised by SHARP, comparable analyses were performed using the AURORA (A Study to Evaluate the Use of Rosuvastatin in Subjects on Regular Hemodialysis: An Assessment of Survival and Cardiovascular Events) trial cohort. AURORA did not provide independent confirmation (vascular access occlusive events: 352 [28.9%] for rosuvastatin versus 337 [27.6%] for placebo; RR, 1.06, 95% CI, 0.91 to 1.23; P=0.44). After combining the two trials, the overall effect of reducing LDL-C with a statin-based regimen on vascular access occlusive events was not statistically significant (707 [29.3%] with any LDL-C–lowering therapy versus 725 [30.5%] with placebo; RR, 0.95, 95% CI, 0.85 to 1.05; P=0.29). Conclusions Exploratory analyses from SHARP suggest that lowering LDL-C with statin-based therapy may improve vascular

  1. Comparison of comorbidities of the Egyptian rheumatoid arthritis patients to the global cohort of the COMORA study: a post-hoc analysis.

    PubMed

    El-Zorkany, Bassel; Mokbel, Abir; Gamal, Sherif M; Mousa, Maha; Youssef, Mohamed; Hmamouchi, Ihsane

    2016-05-01

    The aims of this study are to present the results of Egyptian RA patients included in COMORA cohort and compare it to general COMORA cohort, concerning prevalence of comorbidities, and level of application of recommendations related to detection/prevention of comorbidities. Three-hundred eight Egyptian RA patients included in the cross-sectional, observational, multi-center, international study "COMORA", were compared to the total number of 3612 RA patients. The CRF of COMORA was used in all patients. CRF collects demographic and disease characteristics, comorbidities, risk factors, and compliance with recommendations regarding management of comorbidities. Data were analyzed according to COMORA protocol. Egyptian RA patients were significantly younger, had more active disease, and were more functionally disabled. They showed more frequent use of NSAIDs, methotrexate and steroids and significantly lower use of bDMARDs when compared to non-Egyptians. Egyptian patients had the highest ever HCV prevalence, while depression, hypertension, smoking and dyslipidemia were less prevalent in Egyptians. Prevalence of malignancy risk factors was highly deficient among Egyptians; primarily due to lack of screening. Further, following recommendations for monitoring comorbidities is significantly deficient among Egyptian patients. Egyptian patients had more active disease and more functional impairment than the rest of the COMORA cohort; with lower use of bDMARDs, that is possibly related to the economic situation. Also, there is a clear gap in screening and monitoring comorbidities. Awareness among Egyptian healthcare providers (and possibly similar third-world countries) to detect and manage RA-related comorbidities is required. PMID:26670453

  2. Predictive factors of radiological progression after 2 years of remission-steered treatment in early arthritis patients: a post hoc analysis of the IMPROVED study

    PubMed Central

    Akdemir, Gülşah; Verheul, Marije K; Heimans, Lotte; Wevers-de Boer, Kirsten V C; Goekoop-Ruiterman, Yvonne P M; van Oosterhout, Maikel; Harbers, Joop B; Bijkerk, Casper; Steup-Beekman, Gerda M; Lard, Leroy R; Huizinga, Tom W J; Trouw, Leendert A; Allaart, Cornelia F

    2016-01-01

    Objectives To identify predictive factors of radiological progression in early arthritis patients treated by remission-steered treatment. Methods In the IMPROVED study, 610 patients with early rheumatoid arthritis (RA) or undifferentiated arthritis (UA) were treated with methotrexate (MTX) and a tapered high dose of prednisone. Patients in early remission (disease activity score (DAS) <1.6 after 4 months) tapered prednisone to zero. Patients not in early remission were randomised to arm 1: MTX plus hydroxychloroquine, sulfasalazine and prednisone, or to arm 2: MTX plus adalimumab. Predictors of radiological progression (≥0.5 Sharp/van der Heijde score; SHS) after 2 years were assessed using logistic regression analysis. Results Median (IQR) SHS progression in 488 patients was 0 (0–0) point, without differences between RA or UA patients or between treatment arms. In only 50/488 patients, the SHS progression was ≥0.5: 33 (66%) were in the early DAS remission group, 9 (18%) in arm 1, 5 (10%) in arm 2, 3 (6%) in the outside of protocol group. Age (OR (95% CI): 1.03 (1.00 to 1.06)) and the combined presence of anticarbamylated protein antibodies (anti-CarP) and anticitrullinated protein antibodies (ACPA) (2.54 (1.16 to 5.58)) were independent predictors for SHS progression. Symptom duration <12 weeks showed a trend. Conclusions After 2 years of remission steered treatment in early arthritis patients, there was limited SHS progression in only a small group of patients. Numerically, patients who had achieved early DAS remission had more SHS progression than other patients. Positivity for both anti-CarP and ACPA and age were independently associated with SHS progression. Trial registration numbers ISRCTN Register number 11916566 and EudraCT number 2006 06186-16. PMID:26925251

  3. Is herpes zoster an additional complication in old age alongside comorbidity and multiple medications? Results of the post hoc analysis of the 12-month longitudinal prospective observational ARIZONA cohort study

    PubMed Central

    Pickering, Gisèle; Gavazzi, Gaëtan; Gaillat, Jacques; Paccalin, Marc; Bloch, Karine; Bouhassira, Didier

    2016-01-01

    Objectives To examine the burden of comorbidity, polypharmacy and herpes zoster (HZ), an infectious disease, and its main complication post-herpetic neuralgia (PHN) in young (50–70 years of age: 70−) and old (≥70 years of age: 70+) patients. Design Post hoc analysis of the results of the 12-month longitudinal prospective multicentre observational ARIZONA cohort study. Settings and participants The study took place in primary care in France from 20 November 2006 to 12 September 2008. Overall, 644 general practitioners (GPs) collected data from 1358 patients aged 50 years or more with acute eruptive HZ. Outcome measures Presence of HZ-related pain or PHN (pain persisting >3 months) was documented at day 0 and at months 3, 6, and 12. To investigate HZ and PHN burden, pain, quality of life (QoL) and mood were self-assessed using validated questionnaires (Zoster Brief Pain Inventory, 12-item Short-Form health survey and Hospital Anxiety and Depression Scale, respectively). Results As compared with younger patients, older patients more frequently presented with comorbidities, more frequently took analgesics and had poorer response on all questionnaires, indicating greater burden, at inclusion. Analgesics were more frequently prescribed to relieve acute pain or PHN in 70+ than 70− patients. Despite higher levels of medication prescription, poorer pain relief and poorer response to all questionnaires were reported in 70+ than 70− patients. Conclusions Occurrence of HZ and progression to PHN adds extra burden on top of pharmacological treatment and impaired quality of life, especially in older patients who already have health problems to cope with in everyday life. PMID:26892790

  4. Development of opioid-induced constipation: post hoc analysis of data from a 12-week prospective, open-label, blinded-endpoint streamlined study in low-back pain patients treated with prolonged-release WHO step III opioids

    PubMed Central

    Ueberall, Michael A; Mueller-Schwefe, Gerhard HH

    2015-01-01

    Background Opioid-induced constipation is the most prevalent patient complaint associated with longer-term opioid use and interferes with analgesic efficacy, functionality, quality of life, and patient compliance. Objectives We aimed to compare the effects of prolonged-release (PR) oxycodone plus PR naloxone (OXN) vs PR oxycodone (OXY) vs PR morphine (MOR) on bowel function under real-life conditions in chronic low-back pain patients refractory to World Health Organization (WHO) step I and/or II analgesics. Research design and methods This was a post hoc analysis of the complete data set from a prospective, randomized, open-label, blinded endpoint (PROBE) streamlined study (German pain study registry: 2012-0012-05; European Union Drug Regulating Authorities Clinical Trials [EudraCT]: 2012-001317-16), carried out in 88 centers in Germany, where a total of 901 patients requiring WHO step III opioids to treat low-back pain were enrolled and prospectively observed for 3 months. Opioid allocation was based on either optional randomization (n=453) or physician decision (n=448). In both groups, treatment doses could be adjusted as per the German prescribing information, and physicians were free to address all side effects and tolerability issues as usual. The primary endpoint was the proportion of patients maintaining normal bowel function throughout the complete treatment period, assessed with the Bowel Function Index (BFI). Secondary analyses addressed absolute and relative BFI changes, complete spontaneous bowel movements, use of laxatives, treatment emergent adverse events, analgesic effects, and differences between randomized vs nonrandomized patient groups. Results BFI changed significantly with all three WHO step III treatments, however significantly less with OXN vs OXY and MOR despite a significantly higher use of laxatives with the latter ones (P<0.001). The percentage of patients who maintained normal BFI scores despite opioid treatment was 54.5% (164/301) with

  5. Fundamental study of the austenite formation and decomposition in low-silicon, aluminum added TRIP steels

    NASA Astrophysics Data System (ADS)

    Garcia-Gonzalez, Jose Enrique

    2005-11-01

    TRIP (Transformation Induced Plasticity) steels are under development for automotive applications that require high strength and excellent formability. Conventional TRIP steels consist of a multiphase microstructure comprised of a ferrite matrix with a dispersion of bainite and metastable retained austenite. The high ductility exhibited by these steels results from the transformation of the metastable retained austenite to martensite during straining. In conventional TRIP steel processing, the multiphase microstructure is obtained by controlled cooling from the alpha + gamma region to an isothermal holding temperature. During this holding, bainite forms and carbon is rejected out into the austenite, which lowers the Ms temperature and stabilizes the austenite to room temperature. In this research project, a fundamental study of a low-Si, Mo-Nb added cold rolled TRIP steel with and without Al additions was conducted. In this study, the recrystallization of cold-rolled ferrite, the formation of austenite during intercritical annealing and the characteristics of the decomposition of the intercritically annealed austenite by controlled cooling rates were systematically assessed. Of special interest were: (i) the effect of the initial hot band microstructure, (ii) the formation of epitaxial ferrite during cooling from the intercritical annealing temperature to the isothermal holding temperature, (iii) the influence of the intercritically annealed austenite on the formation of bainite during the isothermal holding temperature, and (iv) the influence of the processing variables on the type, amount, composition and stability of the retained austenite. During this research study, techniques such as OM, SEM, EBSD, TEM, XRD and Magnetometry were used to fully characterize the microstructures. Furthermore, a Gleeble 3500 unit at US Steel Laboratories was used for dilatometry studies and to simulate different CGL processing routes, from which specimens were obtained to evaluate

  6. Value Added?

    ERIC Educational Resources Information Center

    UCLA IDEA, 2012

    2012-01-01

    Value added measures (VAM) uses changes in student test scores to determine how much "value" an individual teacher has "added" to student growth during the school year. Some policymakers, school districts, and educational advocates have applauded VAM as a straightforward measure of teacher effectiveness: the better a teacher, the better students…

  7. Energetics of H 2O dissociation and CO ads+OH ads reaction on a series of Pt-M mixed metal clusters: a relativistic density-functional study

    NASA Astrophysics Data System (ADS)

    Ishikawa, Yasuyuki; Liao, Meng-Sheng; Cabrera, Carlos R.

    2002-07-01

    A relativistic density-functional study of CO adsorption, the energetics of H 2O dehydrogenation, and the CO ads+OH ads reaction has been carried out on a series of Pt-M mixed metal clusters. The metal surface-vacuum interface simulation provides insight into the mechanism of CO ads oxidation on Pt-based bi-functional catalysts. The secondary metals (M) examined are Ru, Sn, Mo, W, Re, Os, Rh, Ir, Cu, Zn, Ge, Pb, and Zr. Cluster models of Pt nM 10- n were used to simulate the catalyst surfaces. The CO ads(Pt) adsorption energies on Pt, Pt-C and C-O bond lengths, force constants, stretching frequencies in mixed Pt-M surfaces are calculated. On the basis of the calculated adsorption energies of H 2O, OH, and H, the reaction energies and activation barriers for H 2O ads(M) dissociation on the M site are estimated. For most of the mixed Pt-M metal surfaces, the presence of M weakens the Pt-C bond and lowers the C-O stretching frequency. The CO ads(Pt) adsorption energy is decreased dramatically by the presence of Mo, W, Os, and Re. These metals also show much higher activity as bi-functional catalysts toward H 2O ads(M) dissociation and formation of OH ads(M) than does pure Pt. However, the oxidative removal of CO ads(Pt) by OH ads(M) is not as favorable on bi-metallic Pt-Mo, Pt-W, Pt-Os, and Pt-Re as on pure Pt, because these alloying metals adsorb OH too strongly. On the basis of the energetics of both H 2O ads(M) dissociation and the CO ads(Pt)+OH ads(M) combination reaction, the best alloying metals for CO oxidation are predicted to be Mo, W, and Os, with Ru following closely.

  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. Prevalence of acute and chronic viral seropositivity and characteristics of disease in patients with psoriatic arthritis treated with cyclosporine: a post hoc analysis from a sex point of view on the observational study of infectious events in psoriasis complicated by active psoriatic arthritis

    PubMed Central

    Colombo, Delia; Chimenti, Sergio; Grossi, Paolo Antonio; Marchesoni, Antonio; Bardazzi, Federico; Ayala, Fabio; Simoni, Lucia; Vassellatti, Donatella; Bellia, Gilberto

    2016-01-01

    Background Sex medicine studies have shown that there are sex differences with regard to disease characteristics in immune-mediated inflammatory diseases, including psoriasis, in immune response and susceptibility to viral infections. We performed a post hoc analysis of the Observational Study of infectious events in psoriasis complicated by active psoriatic arthritis (SYNERGY) study in patients with psoriatic arthritis (PsA) treated with immunosuppressive regimens including cyclosporine, in order to evaluate potential between-sex differences in severity of disease and prevalence of viral infections. Methods SYNERGY was an observational study conducted in 24 Italian dermatology clinics, which included 238 consecutively enrolled patients with PsA, under treatment with immunosuppressant regimens including cyclosporin A. In this post hoc analysis, patients’ demographical data and clinical characteristics of psoriasis, severity and activity of PsA, prevalence of seropositivity for at least one viral infection, and treatments administered for PsA and infections were compared between sexes. Results A total of 225 patients were evaluated in this post hoc analysis, and 121 (54%) were males. Demographic characteristics and concomitant diseases were comparable between sexes. Statistically significant sex differences were observed at baseline in Psoriasis Area and Severity Index score (higher in males), mean number of painful joints, Bath Ankylosing Spondylitis Disease Activity Index, and the global activity of disease assessed by patients (all higher in females). The percentage of patients with at least one seropositivity detected at baseline, indicative of concomitant or former viral infection, was significantly higher among women than among men. No between-sex differences were detected in other measures, at other time points, and in treatments. Patients developed no hepatitis B virus or hepatitis C virus reactivation during cyclosporine treatment. Conclusion Our post hoc

  10. The added value of water footprint assessment for national water policy: a case study for Morocco.

    PubMed

    Schyns, Joep F; Hoekstra, Arjen Y

    2014-01-01

    A Water Footprint Assessment is carried out for Morocco, mapping the water footprint of different activities at river basin and monthly scale, distinguishing between surface- and groundwater. The paper aims to demonstrate the added value of detailed analysis of the human water footprint within a country and thorough assessment of the virtual water flows leaving and entering a country for formulating national water policy. Green, blue and grey water footprint estimates and virtual water flows are mainly derived from a previous grid-based (5 × 5 arc minute) global study for the period 1996-2005. These estimates are placed in the context of monthly natural runoff and waste assimilation capacity per river basin derived from Moroccan data sources. The study finds that: (i) evaporation from storage reservoirs is the second largest form of blue water consumption in Morocco, after irrigated crop production; (ii) Morocco's water and land resources are mainly used to produce relatively low-value (in US$/m3 and US$/ha) crops such as cereals, olives and almonds; (iii) most of the virtual water export from Morocco relates to the export of products with a relatively low economic water productivity (in US$/m3); (iv) blue water scarcity on a monthly scale is severe in all river basins and pressure on groundwater resources by abstractions and nitrate pollution is considerable in most basins; (v) the estimated potential water savings by partial relocation of crops to basins where they consume less water and by reducing water footprints of crops down to benchmark levels are significant compared to demand reducing and supply increasing measures considered in Morocco's national water strategy. PMID:24919194

  11. Impedance study of tea with added taste compounds using conducting polymer and metal electrodes.

    PubMed

    Dhiman, Mopsy; Kapur, Pawan; Ganguli, Abhijit; Singla, Madan Lal

    2012-09-01

    In this study the sensing capabilities of a combination of metals and conducting polymer sensing/working electrodes for tea liquor prepared by addition of different compounds using an impedance mode in frequency range 1 Hz-100 KHz at 0.1 V potential has been carried out. Classification of six different tea liquor samples made by dissolving various compounds (black tea liquor + raw milk from milkman), (black tea liquor + sweetened clove syrup), (black tea liquor + sweetened ginger syrup), (black tea liquor + sweetened cardamom syrup), (black tea liquor + sweet chocolate syrup) and (black tea liquor + vanilla flavoured milk without sugar) using six different working electrodes in a multi electrode setup has been studied using impedance and further its PCA has been carried out. Working electrodes of Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC) and conducting polymer electrodes of Polyaniline (PANI) and Polypyrrole (PPY) grown on an ITO surface potentiostatically have been deployed in a three electrode set up. The impedance response of these tea liquor samples using number of working electrodes shows a decrease in the real and imaginary impedance values presented on nyquist plots depending upon the nature of the electrode and amount of dissolved salts present in compounds added to tea liquor/solution. The different sensing surfaces allowed a high cross-selectivity in response to the same analyte. From Principal Component Analysis (PCA) plots it was possible to classify tea liquor in 3-4 classes using conducting polymer electrodes; however tea liquors were well separated from the PCA plots employing the impedance data of both conducting polymer and metal electrodes. PMID:23035436

  12. The Added Value of Water Footprint Assessment for National Water Policy: A Case Study for Morocco

    PubMed Central

    Schyns, Joep F.; Hoekstra, Arjen Y.

    2014-01-01

    A Water Footprint Assessment is carried out for Morocco, mapping the water footprint of different activities at river basin and monthly scale, distinguishing between surface- and groundwater. The paper aims to demonstrate the added value of detailed analysis of the human water footprint within a country and thorough assessment of the virtual water flows leaving and entering a country for formulating national water policy. Green, blue and grey water footprint estimates and virtual water flows are mainly derived from a previous grid-based (5×5 arc minute) global study for the period 1996–2005. These estimates are placed in the context of monthly natural runoff and waste assimilation capacity per river basin derived from Moroccan data sources. The study finds that: (i) evaporation from storage reservoirs is the second largest form of blue water consumption in Morocco, after irrigated crop production; (ii) Morocco’s water and land resources are mainly used to produce relatively low-value (in US$/m3 and US$/ha) crops such as cereals, olives and almonds; (iii) most of the virtual water export from Morocco relates to the export of products with a relatively low economic water productivity (in US$/m3); (iv) blue water scarcity on a monthly scale is severe in all river basins and pressure on groundwater resources by abstractions and nitrate pollution is considerable in most basins; (v) the estimated potential water savings by partial relocation of crops to basins where they consume less water and by reducing water footprints of crops down to benchmark levels are significant compared to demand reducing and supply increasing measures considered in Morocco’s national water strategy. PMID:24919194

  13. AdS orbifolds and Penrose limits

    SciTech Connect

    Alishahiha, Mohsen; Sheikh-Jabbari, Mohammad M.; Tatar, Radu

    2002-12-09

    In this paper we study the Penrose limit of AdS{sub 5} orbifolds. The orbifold can be either in the pure spatial directions or space and time directions. For the AdS{sub 5}/{Lambda} x S{sup 5} spatial orbifold we observe that after the Penrose limit we obtain the same result as the Penrose limit of AdS{sub 5} x S{sup 5}/{Lambda}. We identify the corresponding BMN operators in terms of operators of the gauge theory on R x S{sup 3}/{Lambda}. The semi-classical description of rotating strings in these backgrounds have also been studied. For the spatial AdS orbifold we show that in the quadratic order the obtained action for the fluctuations is the same as that in S{sup 5} orbifold, however, the higher loop correction can distinguish between two cases.

  14. Value-Added and Observational Measures Used in the Teacher Evaluation Process: A Validation Study

    ERIC Educational Resources Information Center

    Guerere, Claudia

    2013-01-01

    Scores from value-added models (VAMs), as used for educational accountability, represent the educational effect teachers have on their students. The use of these scores in teacher evaluations for high-stakes decision making is new for the State of Florida. Validity evidence that supports or questions the use of these scores is critically needed.…

  15. Inuloxins A-D and derivatives as antileishmanial agents: structure-activity relationship study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inuloxins A-D (1-4) and a-costic acid (5), the phytotoxic compounds previously isolated from Inula viscosa, as well as synthetic derivatives of inuloxin A (compounds 6-10), inuloxin C (compound 11) and inuloxin D (compound 12) were tested in vitro for their activity against Leishmania donovani, the ...

  16. Effect of ferric carboxymaltose on serum phosphate and C-terminal FGF23 levels in non-dialysis chronic kidney disease patients: post-hoc analysis of a prospective study

    PubMed Central

    2013-01-01

    Background Some parenteral iron therapies have been found to be associated with hypophosphatemia. The mechanism of the decrease in serum phosphate is unknown. The aim of this study is to examine the effect of IV ferric carboxymaltose(FCM) on phosphate metabolism and FGF23 levels in patients with chronic kidney disease(CKD). Methods This is a post-hoc analysis of a prospective study carried out in 47 non-dialysis CKD patients with iron-deficiency anaemia who received a single 1000 mg injection of FCM. Markers of mineral metabolism (calcium, phosphate, 1,25-dihydroxyvitamin D, PTH and FGF23[c-terminal]) were measured prior to FCM administration and at week 3 and week 12 after FCM administration. Based on the measured levels of serum phosphate at week 3, patiens were classified as hypophosphatemic or non-hypophosphatemic. Results Serum phosphate levels decreased significantly three weeks after FCM administration and remained at lower levels at week 12 (4.24 ± 0.84 vs 3.69 ± 1.10 vs 3.83 ± 0.68 mg/dL, respectively, p < 0.0001. Serum calcium, PTH and 1,25-dihydroxyvitamin D did not change over the course of the study. Serum FGF23 decreased significantly from 442(44.9-4079.2) at baseline to 340(68.5-2603.3) at week 3 and 191.6(51.3-2465.9) RU/mL at week 12, p < 0.0001. Twelve patients were non-hypophosphatemic and 35 hypophosphatemic. FGF23 levels decreased in both groups, whereas no changes were documented in any of the other mineral parameters. Conclusions In non-dialysis CKD patients, FCM induces reduction in serum phosphate levels that persists for three months. FCM causes a significant decrease in FGF23 levels without changes to other bone metabolism parameters. PMID:23902731

  17. Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study

    PubMed Central

    Martínez Steele, Eurídice; Baraldi, Larissa Galastri; Louzada, Maria Laura da Costa; Moubarac, Jean-Claude; Mozaffarian, Dariush; Monteiro, Carlos Augusto

    2016-01-01

    Objectives To investigate the contribution of ultra-processed foods to the intake of added sugars in the USA. Ultra-processed foods were defined as industrial formulations which, besides salt, sugar, oils and fats, include substances not used in culinary preparations, in particular additives used to imitate sensorial qualities of minimally processed foods and their culinary preparations. Design Cross-sectional study. Setting National Health and Nutrition Examination Survey 2009–2010. Participants We evaluated 9317 participants aged 1+ years with at least one 24 h dietary recall. Main outcome measures Average dietary content of added sugars and proportion of individuals consuming more than 10% of total energy from added sugars. Data analysis Gaussian and Poisson regressions estimated the association between consumption of ultra-processed foods and intake of added sugars. All models incorporated survey sample weights and adjusted for age, sex, race/ethnicity, family income and educational attainment. Results Ultra-processed foods comprised 57.9% of energy intake, and contributed 89.7% of the energy intake from added sugars. The content of added sugars in ultra-processed foods (21.1% of calories) was eightfold higher than in processed foods (2.4%) and fivefold higher than in unprocessed or minimally processed foods and processed culinary ingredients grouped together (3.7%). Both in unadjusted and adjusted models, each increase of 5 percentage points in proportional energy intake from ultra-processed foods increased the proportional energy intake from added sugars by 1 percentage point. Consumption of added sugars increased linearly across quintiles of ultra-processed food consumption: from 7.5% of total energy in the lowest quintile to 19.5% in the highest. A total of 82.1% of Americans in the highest quintile exceeded the recommended limit of 10% energy from added sugars, compared with 26.4% in the lowest. Conclusions Decreasing the consumption of ultra

  18. Numerical Study on Anti-Penetration Process of Alumina Ceramic (AD95) to Tungsten Long Rod Projectiles

    NASA Astrophysics Data System (ADS)

    Zhang, Xianfeng; Zhang, Niansong; Li, Yongchi

    Numerical studies were conducted on the ballistic performance of alumina ceramic (AD95) tiles based on depth of penetration method, when subjected to normal impact of tungsten long rod projectiles at velocities ranging from 1100 to 2000 ms-1. The residual depth on after-effect target was derived in each case, and the ballistic efficiency factor was determined using the corresponding penetration depth on medium carbon steel. Anti-penetration experiment study of the AD95 ceramic tiles to tungsten long rod projectiles has been carried out to verify the accuracy of numerical simulation model. The result shows that numerical simulation results agree well with the corresponding experiment results and AD95 ceramic has excellent ballistic performance than medium carbon steel. The ballistic efficiency factor increases with velocity increasing when impact velocity lower than 1300 ms-1, and when it was higher than 1300 ms-1 the ballistic efficiency factor has almost no difference.

  19. The value of adding optics to ecosystem models: a case study

    NASA Astrophysics Data System (ADS)

    Fujii, M.; Boss, E.; Chai, F.

    2007-05-01

    Many ecosystem models have been developed to study the ocean's biogeochemistry, but most of these models use simple formulations to describe light penetration and spectral quality. Given that processes such as photosynthesis and photo-oxidation are uniquely important for biogeochemical processes in the upper ocean, it is necessary to model light distribution accurately. In addition, the global scale observations of proxies of biogeochemical variables are based on the color of the ocean. The ability to simulate the color of the ocean provides the possibility of comparing model simulation with these observations. Here, an optical model is coupled with a previously published ecosystem model that explicitly represents two phytoplankton (picoplankton and diatoms) and two zooplankton functional groups, as well as multiple nutrients and detritus. Surface ocean color field and subsurface light field are calculated by coupling the ecosystem model with an optical model that relates biogeochemical standing stocks with inherent optical properties (absorption, scattering); this provides input to a commercially available radiative transfer model (Ecolight). We apply this bio-optical model to the equatorial Pacific upwelling region, and find the model to be capable of reproducing many measured optical properties and key biogeochemical processes in this region. Results include large contributions by non-algal particles to the total scattering or attenuation (>50% at 660 nm) and their small contribution to particulate absorption (<20% at 440 nm), and a remarkable contribution by picoplankton to total phytoplankton absorption (>95% at 440 nm). These results are consistent with the field observations. In order to achieve such good agreement between data and model results, however, key model parameters, for which no field data is available, have to be constrained. Sensitivity analysis of the model results to optical parameters reveals the significant role of colored dissolved organic

  20. Study of Cd-chalcogenide/ferri-ferrocyanide photoelectrochemical cells: effect of surface morphology and added salt

    SciTech Connect

    Tenne, R.

    1983-11-01

    The authors carried out an investigation of the Cd-chalcogenide/ferri-ferrocyanide photoelectrochemical cells. In particular, the effect of surface morphology and the effect of added salts upon the characteristics of these cells were investigated. Successive etching with Br/sub 2/ (3%)/methanol, aqua regia, and finally photoetching increases the surface roughness of CdSe (CdS, CdTe) which has a marked effect on the cell characteristics in the ferri-ferrocyanide electrolyte (and polysulfide electrolyte as well). In contrast with polysulfide electrolyte, added salts decrease the output stability of the cell and the onset potential for the photocurrent, which can be explained by the removal of the physiosorbed ferrocyanide ions from the electrode surface by the ions of the salt. On increasing the surface roughness of the electrode, while keeping the salt concentration unchanged, the output stability and the onset potential were increased. A kinetic model is used to explain these phenomena. Thus, added salts can be used to probe the strength of the adsorption of the active electrolyte on the surface of the photoelectrode. Finally, we report on the surface morphology of CdSe and CdTe after irradiation in ferri-ferrocyanide solution and compare our findings to surface morphologies which were observed previously with the help of photoelectrochemical etching (photoetching). It is found that small rectangular crystallites, probably of cadmium ferrocyanide, deposit on the crystal surface during the photocorrosion process in addition to elemental Se(Te).

  1. A Pilot Study of Personal Classified Ads Appearing in Capital-City Daily Newspapers: The Kinds, the Guidelines, the Trends.

    ERIC Educational Resources Information Center

    Lazier-Smith, Linda

    A pilot study examined trends in the appearance of personal advertisements (individuals seeking dates/mates) in the classified columns of daily newspapers located in state capital cities, as well as newspaper guidelines for the acceptance of personal ads. Daily newspapers in the capital city of each state and some of the larger nationally…

  2. The Impact of Student Composition on Schools' Value-Added Performance: A Comparison of Seven Empirical Studies

    ERIC Educational Resources Information Center

    Timmermans, Anneke C.; Thomas, Sally M.

    2015-01-01

    In many countries, policy makers struggle with the development of value-added indicators of school performance for educational accountability purposes and in particular with the choice whether school context measured in the form of student composition variables should be included. This study investigates differences between 7 empirical studies…

  3. Effectiveness Measures for Cross-Sectional Studies: A Comparison of Value-Added Models and Contextualised Attainment Models

    ERIC Educational Resources Information Center

    Lenkeit, Jenny

    2013-01-01

    Educational effectiveness research often appeals to "value-added models (VAM)" to gauge the impact of schooling on student learning net of the effect of student background variables. A huge amount of cross-sectional studies do not, however, meet VAM's requirement for longitudinal data. "Contextualised attainment models (CAM)" measure the influence…

  4. Structure and spectroscopic properties of low-lying states of the HOC(O)O radical.

    PubMed

    Linguerri, Roberto; Puzzarini, Cristina; Francisco, Joseph S

    2016-02-28

    The HOC(O)O radical is a product of the reaction of HOCO radicals with oxygen atoms. The present study provides theoretical prediction of critical spectroscopic features of this radical that should aid in its experimental characterization. Energies, structures, rotational constants, and harmonic frequencies are presented for the ground and two low-lying excited electronic states of HOC(O)O. The energies for the Ã(2)A(″)←X̃(2)A(') and B̃(2)A(')←X̃(2)A(') electronic transitions are reported. The band origin of the B̃←X̃ transition of HOC(O)O is predicted to occur in the near infrared region of the spectrum at around 1.5 eV and it is suggested to be the most promising one for observing this radical spectroscopically. The structural and spectroscopic similarities between HOC(O)O and the isoelectronic radical FC(O)O are discussed. The abundance of experimental data on the FC(O)O radical should guide the spectroscopic characterization of HOC(O)O and serve as a benchmark for the structural and spectroscopic parameters obtained from theory. PMID:26931701

  5. Adding Value.

    ERIC Educational Resources Information Center

    Orsini, Larry L.; Hudack, Lawrence R.; Zekan, Donald L.

    1999-01-01

    The value-added statement (VAS), relatively unknown in the United States, is used in financial reports by many European companies. Saint Bonaventure University (New York) has adapted a VAS to make it appropriate for not-for-profit universities by identifying stakeholder groups (students, faculty, administrators/support personnel, creditors, the…

  6. Does school ethos explain the relationship between value-added education and teenage substance use? A cohort study.

    PubMed

    Markham, Wolfgang A; Young, Robert; Sweeting, Helen; West, Patrick; Aveyard, Paul

    2012-07-01

    Previous studies found lower substance use in schools achieving better examination and truancy results than expected, given their pupil populations (high value-added schools). This study examines whether these findings are replicated in West Scotland and whether school ethos indicators focussing on pupils' perceptions of schooling (environment, involvement, engagement and teacher-pupil relations) mediate the associations. Teenagers from forty-one schools (S2, aged 13, n = 2268; S4, aged 15, n = 2096) previously surveyed in primary school (aged 11, n = 2482) were surveyed in the late 1990s. School value-added scores were derived from standardised residuals of two regression equations separately predicting from pupils' socio-demographic characteristics (1) proportions of pupils passing five Scottish Standard Grade Examinations, and (2) half-day truancy loss. Outcomes were current smoking, monthly drinking, ever illicit drug use. Random effects logistic regression models adjusted for potential pupil-level confounders were used to assess (1) associations between substance use and school-level value-added scores and (2) whether these associations were mediated by pupils' perceptions of schooling or other school-level factors (school roll, religious denomination and mean aggregated school-level ethos scores). Against expectations, value-added education was positively associated with smoking (Odds Ratios [95% confidence intervals] for one standard deviation increase in value-added scores were 1.28 [1.02-1.61] in S2 and 1.13 [1.00-1.27] in S4) and positively but weakly and non-significantly associated with drinking and drug use. Engagement and positive teacher-pupil relations were strongly and negatively associated with all substance use outcomes at both ages. Other school-level factors appeared weakly and largely non-significantly related to substance use. Value-added scores were unrelated to school ethos measures and no ethos measure mediated associations between value-added

  7. The ‘added value’ GPs bring to commissioning: a qualitative study in primary care

    PubMed Central

    Perkins, Neil; Coleman, Anna; Wright, Michael; Gadsby, Erica; McDermott, Imelda; Petsoulas, Christina; Checkland, Kath

    2014-01-01

    Background The 2012 Health and Social Care Act in England replaced primary care trusts with clinical commissioning groups (CCGs) as the main purchasing organisations. These new organisations are GP-led, and it was claimed that this increased clinical input would significantly improve commissioning practice. Aim To explore some of the key assumptions underpinning CCGs, and to examine the claim that GPs bring ‘added value’ to commissioning. Design and setting In-depth interviews with clinicians and managers across seven CCGs in England between April and September 2013. Method A total of 40 clinicians and managers were interviewed. Interviews focused on the perceived ‘added value’ that GPs bring to commissioning. Results Claims to GP ‘added value’ centred on their intimate knowledge of their patients. It was argued that this detailed and concrete knowledge improves service design and that a close working relationship between GPs and managers strengthens the ability of managers to negotiate. However, responders also expressed concerns about the large workload that they face and about the difficulty in engaging with the wider body of GPs. Conclusion GPs have been involved in commissioning in many ways since fundholding in the 1990s, and claims such as these are not new. The key question is whether these new organisations better support and enable the effective use of this knowledge. Furthermore, emphasis on experiential knowledge brings with it concerns about representativeness and the extent to which other voices are heard. Finally, the implicit privileging of GPs’ personal knowledge ahead of systematic public health intelligence also requires exploration. PMID:25348997

  8. Pure and Sr(II)-added copper aluminate nanocomposites: structural, electrical and alcohol sensing studies.

    PubMed

    Kumar, R Thinesh; Vijaya, J Judith; Kennedy, L John

    2013-08-01

    The effect of ethylenediamine addition in the sol-gel method for the preparation of pure and Sr(II)-added nano copper aluminate (CuAl2O4) composites for the enhancement in their structural, electrical, and alcohol sensing properties were investigated. The effect of addition of Sr(II) to pure CuAl2O4 in both the methods were also discussed. X-ray diffraction, scanning electron microscopy, nitrogen adsorption/desorption isotherms, temperature dependant conductance measurements and thermoelectric power measurements were used to characterize the composites prepared. Among the composites, 0.8 molar ratio strontium added copper aluminate composite prepared by modified sol-gel method showed the highest sensitivity towards alcohols. The stability, response and recovery of MS-CuSA5 were also discussed. The response and recovery characteristics showed that the order of sensing alcohols by the composites was butanol > isopropanol > ethanol > methanol, which could be explained on the basis of oxidation of alcohols. PMID:23882857

  9. Feasibility study of a wearable exoskeleton for children: is the gait altered by adding masses on lower limbs?

    PubMed

    Rossi, Stefano; Colazza, Alessandra; Petrarca, Maurizio; Castelli, Enrico; Cappa, Paolo; Krebs, Hermano Igo

    2013-01-01

    We are designing a pediatric exoskeletal ankle robot (pediatric Anklebot) to promote gait habilitation in children with Cerebral Palsy (CP). Few studies have evaluated how much or whether the unilateral loading of a wearable exoskeleton may have the unwanted effect of altering significantly the gait. The purpose of this study was to evaluate whether adding masses up to 2.5 kg, the estimated overall added mass of the mentioned device, at the knee level alters the gait kinematics. Ten healthy children and eight children with CP, with light or mild gait impairment, walked wearing a knee brace with several masses. Gait parameters and lower-limb joint kinematics were analyzed with an optoelectronic system under six conditions: without brace (natural gait) and with masses placed at the knee level (0.5, 1.0, 1.5, 2.0, 2.5 kg). T-tests and repeated measures ANOVA tests were conducted in order to find noteworthy differences among the trial conditions and between loaded and unloaded legs. No statistically significant differences in gait parameters for both healthy children and children with CP were observed in the five "with added mass" conditions. We found significant differences among "natural gait" and "with added masses" conditions in knee flexion and hip extension angles for healthy children and in knee flexion angle for children with CP. This result can be interpreted as an effect of the mechanical constraint induced by the knee brace rather than the effect associated with load increase. The study demonstrates that the mechanical constraint induced by the brace has a measurable effect on the gait of healthy children and children with CP and that the added mass up to 2.5 kg does not alter the lower limb kinematics. This suggests that wearable devices weighing 25 N or less will not noticeably modify the gait patterns of the population examined here. PMID:24023822

  10. Feasibility Study of a Wearable Exoskeleton for Children: Is the Gait Altered by Adding Masses on Lower Limbs?

    PubMed Central

    Rossi, Stefano; Colazza, Alessandra; Petrarca, Maurizio; Castelli, Enrico; Cappa, Paolo; Krebs, Hermano Igo

    2013-01-01

    We are designing a pediatric exoskeletal ankle robot (pediatric Anklebot) to promote gait habilitation in children with Cerebral Palsy (CP). Few studies have evaluated how much or whether the unilateral loading of a wearable exoskeleton may have the unwanted effect of altering significantly the gait. The purpose of this study was to evaluate whether adding masses up to 2.5 kg, the estimated overall added mass of the mentioned device, at the knee level alters the gait kinematics. Ten healthy children and eight children with CP, with light or mild gait impairment, walked wearing a knee brace with several masses. Gait parameters and lower-limb joint kinematics were analyzed with an optoelectronic system under six conditions: without brace (natural gait) and with masses placed at the knee level (0.5, 1.0, 1.5, 2.0, 2.5 kg). T-tests and repeated measures ANOVA tests were conducted in order to find noteworthy differences among the trial conditions and between loaded and unloaded legs. No statistically significant differences in gait parameters for both healthy children and children with CP were observed in the five “with added mass” conditions. We found significant differences among “natural gait” and “with added masses” conditions in knee flexion and hip extension angles for healthy children and in knee flexion angle for children with CP. This result can be interpreted as an effect of the mechanical constraint induced by the knee brace rather than the effect associated with load increase. The study demonstrates that the mechanical constraint induced by the brace has a measurable effect on the gait of healthy children and children with CP and that the added mass up to 2.5 kg does not alter the lower limb kinematics. This suggests that wearable devices weighing 25 N or less will not noticeably modify the gait patterns of the population examined here. PMID:24023822

  11. Direct test of the AdS/CFT correspondence by Monte Carlo studies of super Yang-Mills theory

    NASA Astrophysics Data System (ADS)

    Honda, Masazumi; Ishiki, Goro; Kim, Sang-Woo; Nishimura, Jun; Tsuchiya, Asato

    2013-11-01

    We perform nonperturbative studies of super Yang-Mills theory by Monte Carlo simulation. In particular, we calculate the correlation functions of chiral primary operators to test the AdS/CFT correspondence. Our results agree with the predictions obtained from the AdS side that the SUSY non-renormalization property is obeyed by the three-point functions but not by the four-point functions investigated in this paper. Instead of the lattice regularization, we use a novel regularization of the theory based on an equivalence in the large- N limit between the SU( N) theory on R × S 3 and a one-dimensional SU( N) gauge theory known as the plane-wave (BMN) matrix model. The equivalence extends the idea of large- N reduction to a curved space and, at the same time, overcomes the obstacle related to the center symmetry breaking. The adopted regularization for S 3 preserves 16 SUSY, which is crucial in testing the AdS/CFT correspondence with the available computer resources. The only SUSY breaking effects, which come from the momentum cutoff Λ in R direction, are made negligible by using sufficiently large Λ.

  12. Charge Carrier Relaxation Study in Glass-Added Barium Titanate Ceramics Using Thermally Stimulated Depolarization Current

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhang, Yong; Liu, Xiaolin; Song, Xiaozhen; Zhu, Jia; Baturin, Ivan

    2016-08-01

    The depolarization process of glass-added barium titanate (BaTiO3) ceramics with two different glass concentrations was investigated using a thermally stimulated depolarization current (TSDC) technique. The TSDC spectra of the glass-added BaTiO3 ceramics show three peaks. The first sharp peak near the Curie temperature is due to pyroelectric current associated with ferroelectric-paraelectric phase transition. The middle temperature peak at about 200°C showed no dependence on the depolarization current peak position in the polarization field, and the activation energies of this peak were between 0.43 eV and 0.55 eV, which are attributed to the behavior of defect dipoles related to oxygen vacancies within the BaTiO3 grains. Moreover, the high temperature peak at around 300°C indicated that the depolarization current peak position depends on the polarization temperature and decreases with increasing polarization field. The activation energy of this high temperature peak was between 0.78 eV and 0.98 eV, which is similar to the activation energy for the motion of oxygen vacancies in perovskite oxides. The high temperature peak could be attributed to the migration of oxygen vacancies across grain boundaries. In this work we developed a model in which oxygen vacancies that originated from the defect within grains migrated from the anode to the cathode and some were trapped at the grain boundaries. It is presented here and successfully interprets the appearance and behavior of these peaks.

  13. Possible association between phages, Hoc protein, and the immune system.

    PubMed

    Dabrowska, K; Switała-Jeleń, K; Opolski, A; Górski, A

    2006-02-01

    Mammals have become "an environment" for enterobacterial phage life cycles. Therefore it could be expected that bacteriophages adapt to them. This adaptation must comprise bacteriophage proteins. Gp Hoc seems to have significance neither for phage particle structure nor for phage antibacterial activity. It is evidently not necessary for the "typical" antibacterial actions of bacteriophages. But the rules of evolution make it improbable that gp Hoc really has no function, and non-essential genes of T4-type phages are probably important for phages' adaptation to their particular lifestyle. More interesting is the eukaryotic origin of gp Hoc: a resemblance to immunoglobulin-like proteins that reflects their evolutionary relation. Substantial differences in biological activity between T4 and a mutant that lacks gp Hoc were observed in a mammalian system. Hoc protein seems to be one of the molecules predicted to interact with mammalian organisms and/or modulate these interactions. PMID:16195787

  14. Methodological Aspects of the Phase II Study AFF006 Evaluating Amyloid-beta -Targeting Vaccine AFFITOPE® AD02 in Early Alzheimer’s Disease – Prospective Use of Novel Composite Scales

    PubMed Central

    Hendrix, S.; Ellison, N.; Stanworth, S.; Tierney, L.; Mattner, F.; Schmidt, W.; Dubois, B.; Schneeberger, A.

    2015-01-01

    BACKGROUND Optimized scales and composite outcomes have been proposed as a way to more accurately measure Alzheimer’s disease related decline. AFFITOPE® AD02, is an amyloid-beta (Aβ)-targeting vaccine to elicit anti-Aβ antibodies. IMM-AD04, commonly known as Alum, originally designated as a control agent, appeared to have disease-modifying activity in a multicenter, parallel group phase II study in early AD patients. OBJECTIVES To develop adapted outcomes for cognition, function and a composite scale with improved sensitivity to decline and treatment effects in early AD (mild plus prodromal AD) based on historical data and to assess these adapted outcomes in this phase II study. DESIGN Data from public datasets was analyzed using a partial least squares model in order to identify an optimally weighted cognitive outcome, Adapted ADAS-cog, and an optimally weighted ADL outcome, Adapted ADCS-ADL which were prospectively defined as co-primary endpoints for the study and were also combined into a composite scale. Data from 162 patients in the placebo groups of ADCS studies and 156 mild patients in the ADNI I study were pooled for this analysis. The Adapted ADAS-cog scale considered 13 ADAS-cog items as well as several Neuropsychological test items and CogState items, the Adapted ADCS-ADL considered all ADCS-ADL items. After the pre-specified analyses were complete, additional adapted and composite scales were investigated in a post-hoc manner. Evaluation of the adapted and composite scales was performed on Phase II trial data for AFFITOPE® AD02 (AFF006, Clinical Trial Identifier: NCT01117818) and historic data in early AD. Least square means, standard deviations, and least squares mean to standard deviation ratios were compared among adapted and composite scales and traditional scales for the 5 treatment groups in the phase II study and overall for the historic data. Treatment effect sizes and p-values were also compared for the phase II study. RESULTS Cognitive

  15. Recovery of Weak Factor Loadings When Adding the Mean Structure in Confirmatory Factor Analysis: A Simulation Study

    PubMed Central

    Ximénez, Carmen

    2016-01-01

    This article extends previous research on the recovery of weak factor loadings in confirmatory factor analysis (CFA) by exploring the effects of adding the mean structure. This issue has not been examined in previous research. This study is based on the framework of Yung and Bentler (1999) and aims to examine the conditions that affect the recovery of weak factor loadings when the model includes the mean structure, compared to analyzing the covariance structure alone. A simulation study was conducted in which several constraints were defined for one-, two-, and three-factor models. Results show that adding the mean structure improves the recovery of weak factor loadings and reduces the asymptotic variances for the factor loadings, particularly for the models with a smaller number of factors and a small sample size. Therefore, under certain circumstances, modeling the means should be seriously considered for covariance models containing weak factor loadings. PMID:26779071

  16. Evidence for added value of convection-permitting models for studying changes in extreme precipitation

    NASA Astrophysics Data System (ADS)

    Meredith, Edmund; Maraun, Douglas; Semenov, Vladimir; Park, Wonsun

    2016-04-01

    Climate model resolution can affect both the climate change signal and present-day representation of extreme precipitation. The need to parametrize convective processes raises questions about how well the response to warming of convective precipitation extremes is captured in such models. In particular, coastal precipitation extremes can be sensitive to sea surface temperature (SST) increase. Taking a recent coastal precipitation extreme as a showcase example, we explore the added value of convection-permitting models by comparing the response of the extreme precipitation to a wide range of SST forcings in an ensemble of regional climate model simulations using parametrized and explicit convection. Compared at the same spatial scale, we find that the increased local intensities of vertical motion and precipitation in the convection-permitting simulations play a crucial role in shaping a strongly nonlinear extreme precipitation response to SST increase, which is not evident when convection is parametrized. In the convection-permitting simulations, SST increase causes precipitation intensity to increase only until a threshold is reached, beyond which further SST increase does not enhance the precipitation. This flattened response results from an improved representation of convective downdrafts and near-surface cooling, which damp the further intensification of precipitation by stabilizing the lower troposphere locally and also create cold pools that cause subsequent convection to be triggered at sea, rather than by the coastal orography. These features are not well represented in the parametrized convection simulations, resulting in precipitation intensity having a much more linear response to increasing SSTs.

  17. Study on transient beam loading compensation for China ADS proton linac injector II

    NASA Astrophysics Data System (ADS)

    Gao, Zheng; He, Yuan; Wang, Xian-Wu; Chang, Wei; Zhang, Rui-Feng; Zhu, Zheng-Long; Zhang, Sheng-Hu; Chen, Qi; Powers, Tom

    2016-05-01

    Significant transient beam loading effects were observed during beam commissioning tests of prototype II of the injector for the accelerator driven sub-critical (ADS) system, which took place at the Institute of Modern Physics, Chinese Academy of Sciences, between October and December 2014. During these tests experiments were performed with continuous wave (CW) operation of the cavities with pulsed beam current, and the system was configured to make use of a prototype digital low level radio frequency (LLRF) controller. The system was originally operated in pulsed mode with a simple proportional plus integral and deviation (PID) feedback control algorithm, which was not able to maintain the desired gradient regulation during pulsed 10 mA beam operations. A unique simple transient beam loading compensation method which made use of a combination of proportional and integral (PI) feedback and feedforward control algorithm was implemented in order to significantly reduce the beam induced transient effect in the cavity gradients. The superconducting cavity field variation was reduced to less than 1.7% after turning on this control algorithm. The design and experimental results of this system are presented in this paper. Supported by National Natural Science Foundation of China (91426303, 11525523)

  18. Study of the thermo-magnetic fluctuations in carbon nano-tubes added Bi-2223 superconductors

    NASA Astrophysics Data System (ADS)

    Saoudel, A.; Amira, A.; Boudjadja, Y.; Mahamdioua, N.; Amirouche, L.; Varilci, A.; Altintas, S. P.; Terzioglu, C.

    2013-11-01

    We have investigated the effect of addition of carbon nano-tubes (CNT) on the properties of Bi1.6Pb0.4Sr2Ca2Cu3Oy superconductors. The samples are prepared from commercial powders with addition of 0.1 wt% of CNT. They are characterized by XRD, SEM and magneto-resistivity in the transition region. As it was reported for CNT added Y-123 compounds, the refined cell parameters are practically independent of this kind of addition. Under applied magnetic field, a large broadening of resistive transition is observed. The dissipative behavior of resistivity can be explained using the well known expression, ρ=ρ0(T/Tg-1)S. The modified vortex-glass to liquid transition theory is used to calculate the values of the glass-transition temperature Tg and the temperature and magnetic field dependent activation energy U0(B,T). These parameters are seen to decrease with CNT addition and applied magnetic field. Also, we have found that the undoped sample proves a better transition width, residual resistivity (ρ0) and a higher onset critical transition temperature of about 117.75 K. Also, the appearance of a double resistive transition for both samples is a confirmation of the existence of a secondary phase which plays the role of the weak links at the grain boundaries.

  19. Complexation study on no-carrier-added astatine with insulin: a candidate radiopharmaceutical.

    PubMed

    Lahiri, Susanta; Roy, Kamalika; Sen, Souvik

    2008-12-01

    No-carrier-added astatine radionuclides produced in the (7)Li-irradiated lead matrix were separated from bulk lead nitrate target by complexing At with insulin, followed by dialysis. The method offers simultaneous separation of At from lead as well as its complexation with insulin. The At-insulin complex might be a potential radiopharmaceutical in the treatment of hepatocellular carcinoma. The stability of At-insulin complex was checked by dialysis against deionized water and Ringer lactate (RL) solution. It has been found that the half-life of At-insulin complex is about approximately 12h, when dialyzed against deionized water and is only 6h, when dialyzed against RL solution having the same composition as blood serum. The 6h half-life of this Insulin-At complex is perfect for killing cancer cells from external cell surfaces as the half-life of internalization of insulin molecule inside the cell is 7-12h. PMID:18674921

  20. Study of surfactant-added TMAH for applications in DRIE and wet etching-based micromachining

    NASA Astrophysics Data System (ADS)

    Tang, B.; Shikida, M.; Sato, K.; Pal, P.; Amakawa, H.; Hida, H.; Fukuzawa, K.

    2010-06-01

    In this paper, etching anisotropy is evaluated for a number of different crystallographic orientations of silicon in a 0.1 vol% Triton-X-100 added 25 wt% tetramethylammonium hydroxide (TMAH) solution using a silicon hemisphere. The research is primarily aimed at developing advanced applications of wet etching in microelectromechanical systems (MEMS). The etching process is carried out at different temperatures in the range of 61-81 °C. The etching results of silicon hemisphere and different shapes of three-dimensional structures in {1 0 0}- and {1 1 0}-Si surfaces are analyzed. Significantly important anisotropy, different from a traditional etchant (e.g. pure KOH and TMAH), is investigated to extend the applications of the wet etching process in silicon bulk micromachining. The similar etching behavior of exact and vicinal {1 1 0} and {1 1 1} planes in TMAH + Triton is utilized selectively to remove the scalloping from deep reactive-ion etching (DRIE) etched profiles. The direct application of the present research is demonstrated by fabricating a cylindrical lens with highly smooth etched surface finish. The smoothness of a micro-lens at different locations is measured qualitatively by a scanning electron microscope and quantitatively by an atomic force microscope. The present paper provides a simple and effective fabrication method of the silicon micro-lens for optical MEMS applications.

  1. Comparative studies of glycine added potassium dihydrogen phosphate single crystals grown by conventional and Sankaranaryanan-Ramasamy methods

    NASA Astrophysics Data System (ADS)

    Boopathi, K.; Rajesh, P.; Ramasamy, P.; Manyum, Prapun

    2013-03-01

    Glycine added potassium dihydrogen phosphate (KDP) crystals have been grown by slow evaporation solution technique, slow cooling along with seed rotation and Sankaranaryanan-Ramasamy (SR) method. The size of the grown crystal in slow cooling method was 35 × 25 × 20 mm3 and in SR method it was 20 mm in diameter and 110 mm in length. The grown crystals were subjected to powder X-ray diffraction, UV-Vis, thermal analysis, Vickers microhardness, dielectric, laser damage threshold, higher resolution X-ray diffraction (HRXRD) and nonlinear optical (NLO) studies. All the grown crystals have good transparency in the entire visible region. In order to determine mechanical strength of crystal, Vickers micro-hardness measurement was carried out. Dielectric study reveals higher dielectric constant and low dielectric loss for SR method grown crystal. High laser damage threshold was observed in SR method grown glycine added KDP crystal compared to SR method grown pure KDP crystal. The second harmonic efficiency of the glycine added KDP is increased compared to pure KDP.

  2. Two Virasoro symmetries in stringy warped AdS3

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    We study three-dimensional consistent truncations of type IIB supergravity which admit warped AdS3 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 AdS3. Consequently, for each consistent choice of boundary conditions in AdS3, we can define a consistent phase space in warped AdS3 with identical conserved charges. This way, we easily obtain a Virasoro × Virasoro asymptotic symmetry algebra in warped AdS3; two different types of Virasoro × Kač-Moody symmetries are also consistent alternatives.

  3. Bubbling AdS3

    NASA Astrophysics Data System (ADS)

    Martelli, Dario; Morales, Jose F.

    2005-02-01

    In the light of the recent Lin, Lunin, Maldacena (LLM) results, we investigate 1/2-BPS geometries in minimal (and next to minimal) supergravity in D = 6 dimensions. In the case of minimal supergravity, solutions are given by fibrations of a two-torus T2 specified by two harmonic functions. For a rectangular torus the two functions are related by a non-linear equation with rare solutions: AdS3 × S3, the pp-wave and the multi-center string. ``Bubbling'', i.e. superpositions of droplets, is accommodated by allowing the complex structure of the T2 to vary over the base. The analysis is repeated in the presence of a tensor multiplet and similar conclusions are reached, with generic solutions describing D1D5 (or their dual fundamental string-momentum) systems. In this framework, the profile of the dual fundamental string-momentum system is identified with the boundaries of the droplets in a two-dimensional plane.

  4. Student Self-Assessment in HOCS Science Examinations: Is There a Problem?

    NASA Astrophysics Data System (ADS)

    Zoller, Uri; Ben-Chaim, David

    1998-06-01

    A specially-designed self-assessment questionnaire (SAQHOCS), containing higher-order cognitive skills (HOCS)-type questions, was administered to 71 biology majors, enrolled in a four-year college program. The gap between students' self-assessment marking, and that of their HOCS-biased teachers (the authors), is accounted for by the prevailing LOCS-orientation and the "testing culture"—a total separation between testing and learning—in contemporary science teaching. The majority of the students in the study evaluated themselves as capable of self-assessment, and felt reasonably confident in doing so. They were quite reserved as far as the applicability of the self-assessment method to nonalgorithmic ("correct/incorrect") questions is concerned. The results of this study suggest that the potential for student self-assessment within college science teaching and learning exists. However, still a great purposed effort in HOCS-oriented teaching and learning is required in order for the student self-assessment practice to become a routine integral component of HOCS science examinations.

  5. Adding New Dimensions to Case Study Evaluations: The Case of Evaluating Comprehensive Reforms

    ERIC Educational Resources Information Center

    Yin, Robert K.; Davis, Darnella

    2007-01-01

    This chapter describes the adaptation of the case study method to assessing increasingly complex, comprehensive reform initiatives that highlight the blurring of the boundaries between phenomenon and context and the concurrence of multiple interventions. Completed studies of two education reform programs illustrate the ongoing challenges of…

  6. Proceedings of the AD HOC Workshop on Ceramics for Li/FeS{sub 2} batteries

    SciTech Connect

    Not Available

    1993-12-31

    Representatives from industry, the U.S. Advanced Battery Consortium (USABC), DOE, national laboratories, and other govt agencies met to develop recommendations and actions for accelerating the development of ceramic components critical to the successful introduction of the Li/FeS{sub 2} bipolar battery for electric vehicles. Most of the workshop is devoted to electrode materials, bipolar designs, separators, and bipolar plates. The bulk of this document is viewographs and is divided into: ceramics, USABC overview, SAFT`s Li/FeS{sub 2} USABC program, bipolar Li/FeS{sub 2} component development, design requirements for bipolar plates, separator design requirements, compatibility of ceramic insulators with lithium, characterization of MgO for use in separators, resistivity measurements of separators, sintered AlN separators for LiMS batteries, etc.

  7. Ad-hoc model acquisition for combat simulation in urban terrain

    NASA Astrophysics Data System (ADS)

    Bulatov, Dimitri; Solbrig, Peter; Wernerus, Peter

    2012-10-01

    Situation awareness in complex urban environments is an important component for a successful task fulfillment both in military and civil area of applications. In the first area, the fields of deployment of the members of the North Atlantic Alliance have been changed, in the past two decades, from the originally assigned task of acting as national and allied defense forces within the partners' own borders to out-of-area missions under conditions of an asymmetric conflict. Because of its complicated structure, urban terrain represents a particular difficulty of military missions such as patrolling. In the civil field of applications, police and rescue forces are also often strongly dependent on a local visibility and accessibility analysis. However, the process of decision-taking within a short time and under enormous pressure can be extensively trained in an environment that is tailored to the concrete situation. The contribution of this work consists of context-based modeling of urban terrain that can be then integrated into simulation software, for example, Virtual Battlespace 2 (VBS2). The input of our procedure is made up by the airborne sensor data, collected either by an active or a passive sensor. The latter is particularly important if the application is time-critical or the area to be explored is small. After description of our procedure for urban terrain modeling with a detailed focus on the recent innovations, the main steps of model integration into simulation software will be presented and two examples of missions for military and civil applications that can be easily created with VBS2 will be given.

  8. Informal, Incidental and Ad Hoc: The Information-Seeking and Learning Strategies of Health Care Patients

    ERIC Educational Resources Information Center

    Papen, Uta

    2012-01-01

    When people are ill, they want to know what is happening to them and how they can get better. Current health policies support patients' access to health information and encourage them to take part in decisions regarding their health. But little is known about how patients learn and the difficulties they may encounter in the process. This paper…

  9. Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks.

    PubMed

    Liu, Ming; Xu, Yang; Mohammed, Abdul-Wahid

    2016-01-01

    Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent's limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent's cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent's view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved. PMID:26727504

  10. Report of the "MLA Bibliography" Scope and Overlap Committee, an ACRL Ad Hoc Committee.

    ERIC Educational Resources Information Center

    Association of Coll. and Research Libraries, Chicago, IL.

    The "MLA Bibliography" Scope and Overlap Committee was formed in response to a request from the Modern Language Association for librarians' assistance in examining the coverage and overlap between the "MLA International Bibliography" and other reference tools. This report contains the following 20 papers, prepared by the committee between 1991 and…

  11. Peak sidelobe level distribution computation for ad hoc arrays using extreme value theory

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, Siddhartha

    An equipment setup for manufacturing nanolaminates with potential applications as protective coatings and in transparent armor was designed and constructed to improve upon an existing system in place at UMass Lowell. The design modification was targeted at maximizing the area of the produced nanolaminates. The new design was successful in that the nanolaminates were approximatively 4.5 times larger in area than the ones produced on the previous design. Nanolaminates consisting of poly(1,4- cyclohexanedimethylene terephthalate-co-2,2,4,4-tetramethyl-1,3-cyclobutylene terephalate) (Tritan TX1000 and TX2000, Eastman Chemical) and dimethylditallowammonium montmorillonite clay nanofiller (Cloisite 20A, Southern Clay Products) were produced using the new setup. Nanolaminates with clay loadings of 0%, 10%, 30%, and 50% by volume were produced as freestanding films in the case of both grades of copolyester, while adherent films were produced at clay loadings of 70% and 90% by volume were in the case of Tritan TX2000. Finally, chemical and mechanical characterization of all freestanding films was attempted in order to develop preliminary structure-properties relations for these novel materials.

  12. Decentralized Opportunistic Spectrum Resources Access Model and Algorithm toward Cooperative Ad-Hoc Networks

    PubMed Central

    Liu, Ming; Xu, Yang; Mohammed, Abdul-Wahid

    2016-01-01

    Limited communication resources have gradually become a critical factor toward efficiency of decentralized large scale multi-agent coordination when both system scales up and tasks become more complex. In current researches, due to the agent’s limited communication and observational capability, an agent in a decentralized setting can only choose a part of channels to access, but cannot perceive or share global information. Each agent’s cooperative decision is based on the partial observation of the system state, and as such, uncertainty in the communication network is unavoidable. In this situation, it is a major challenge working out cooperative decision-making under uncertainty with only a partial observation of the environment. In this paper, we propose a decentralized approach that allows agents cooperatively search and independently choose channels. The key to our design is to build an up-to-date observation for each agent’s view so that a local decision model is achievable in a large scale team coordination. We simplify the Dec-POMDP model problem, and each agent can jointly work out its communication policy in order to improve its local decision utilities for the choice of communication resources. Finally, we discuss an implicate resource competition game, and show that, there exists an approximate resources access tradeoff balance between agents. Based on this discovery, the tradeoff between real-time decision-making and the efficiency of cooperation using these channels can be well improved. PMID:26727504

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

    PubMed Central

    Madhusudhanan, B.; Chitra, S.; Rajan, C.

    2015-01-01

    In MANET multicasting, forward and backward secrecy result in increased packet drop rate owing to mobility. Frequent rekeying causes large message overhead which increases energy consumption and end-to-end delay. Particularly, the prevailing group key management techniques cause frequent mobility and disconnections. So there is a need to design a multicast key management technique to overcome these problems. In this paper, we propose the mobility based key management technique for multicast security in MANET. Initially, the nodes are categorized according to their stability index which is estimated based on the link availability and mobility. A multicast tree is constructed such that for every weak node, there is a strong parent node. A session key-based encryption technique is utilized to transmit a multicast data. The rekeying process is performed periodically by the initiator node. The rekeying interval is fixed depending on the node category so that this technique greatly minimizes the rekeying overhead. By simulation results, we show that our proposed approach reduces the packet drop rate and improves the data confidentiality. PMID:25834838

  14. A Review of LIDAR Radiometric Processing: From Ad Hoc Intensity Correction to Rigorous Radiometric Calibration

    PubMed Central

    Kashani, Alireza G.; Olsen, Michael J.; Parrish, Christopher E.; Wilson, Nicholas

    2015-01-01

    In addition to precise 3D coordinates, most light detection and ranging (LIDAR) systems also record “intensity”, loosely defined as the strength of the backscattered echo for each measured point. To date, LIDAR intensity data have proven beneficial in a wide range of applications because they are related to surface parameters, such as reflectance. While numerous procedures have been introduced in the scientific literature, and even commercial software, to enhance the utility of intensity data through a variety of “normalization”, “correction”, or “calibration” techniques, the current situation is complicated by a lack of standardization, as well as confusing, inconsistent use of terminology. In this paper, we first provide an overview of basic principles of LIDAR intensity measurements and applications utilizing intensity information from terrestrial, airborne topographic, and airborne bathymetric LIDAR. Next, we review effective parameters on intensity measurements, basic theory, and current intensity processing methods. We define terminology adopted from the most commonly-used conventions based on a review of current literature. Finally, we identify topics in need of further research. Ultimately, the presented information helps lay the foundation for future standards and specifications for LIDAR radiometric calibration. PMID:26561813

  15. Energy Efficient and Stable Weight Based Clustering for Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Bouk, Safdar H.; Sasase, Iwao

    Recently several weighted clustering algorithms have been proposed, however, to the best of our knowledge; there is none that propagates weights to other nodes without weight message for leader election, normalizes node parameters and considers neighboring node parameters to calculate node weights. In this paper, we propose an Energy Efficient and Stable Weight Based Clustering (EE-SWBC) algorithm that elects cluster heads without sending any additional weight message. It propagates node parameters to its neighbors through neighbor discovery message (HELLO Message) and stores these parameters in neighborhood list. Each node normalizes parameters and efficiently calculates its own weight and the weights of neighboring nodes from that neighborhood table using Grey Decision Method (GDM). GDM finds the ideal solution (best node parameters in neighborhood list) and calculates node weights in comparison to the ideal solution. The node(s) with maximum weight (parameters closer to the ideal solution) are elected as cluster heads. In result, EE-SWBC fairly selects potential nodes with parameters closer to ideal solution with less overhead. Different performance metrics of EE-SWBC and Distributed Weighted Clustering Algorithm (DWCA) are compared through simulations. The simulation results show that EE-SWBC maintains fewer average numbers of stable clusters with minimum overhead, less energy consumption and fewer changes in cluster structure within network compared to DWCA.

  16. MSG Instant Messenger: Social Presence and Location for the "'Ad Hoc' Learning Experience"

    ERIC Educational Resources Information Center

    Little, Alex; Denham, Chris; Eisenstadt, Marc

    2008-01-01

    "Elearning2.0" promises to harness the power of three of today's most disruptive technologies: social software, elearning, and Web2.0. Our own work in this disruptive space takes as a starting premise that social networking is critical for learning: finding the right person can be more important than "scouring the web for an answer" particularly…

  17. Remote detection of riverine traffic using an ad hoc wireless sensor network

    NASA Astrophysics Data System (ADS)

    Athan, Stephan P.

    2005-05-01

    Trafficking of illegal drugs on riverine and inland waterways continues to proliferate in South America. While there has been a successful joint effort to cut off overland and air trafficking routes, there exists a vast river network and Amazon region consisting of over 13,000 water miles that remains difficult to adequately monitor, increasing the likelihood of narcotics moving along this extensive river system. Hence, an effort is underway to provide remote unattended riverine detection in lieu of manned or attended detection measures.

  18. Performance Evaluation of Mobile Ad Hoc Network Based Communications for Future Mobile Tele-Emergency System

    NASA Astrophysics Data System (ADS)

    Viswacheda, D. V.; Barukang, L.; Hamid, M. Y.; Arifianto, M. S.

    Sparked by awareness of the limitations to provide medical services in remote areas, researchers have perceived that developing telemedicine systems is inevitable. In most cases very remote areas and disaster struck areas lack telecommunication infrastructure. Telemedicine system operating in such areas must have advanced wireless technology supporting it in devastating situation, hence it is called as tele-emergency system. Our approach is on MANET combined with Mobile IP and MIPV6, is the basis of infrastructure for the mobile tele-emergency system. The tele-emergency system requires data, voice and video transmission in its network. In this investigation, evaluation is based on simulation of the various ITU-T standard CODECs of VoIP and video transmission over MANET using discrete event simulator NS-2. The results of simulation showed that ITU-T G723.1 worked well in the MANET environment than the other CODECs for VoIP in fixed and mobility tele-emergency environments. From the simulation of video CODEC performance evaluation, it was observed that H.263 performed to a great extent in random small scale environment and also in multiple video flow of 57.6kbps speed video transmission.

  19. Solar-powered ad-hoc wireless sensor network for border surveillance

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    Wireless sensor networks (WSNs) have emerged as means of providing automated monitoring, target tracking, and intrusion detection. Solar-powered WSNs that adopt innovative sensors with low power consumption and forefront networking technologies can provide rapidly deployable situational awareness and effective security control at the border at low cost. In our paper, we introduce the prototype of our new solar-powered WSN platform for Border Security. We consider practical issues in WSNs, including sensing environment classification, survivability under harsh weather conditions, and efficient solar energy harvesting. Experimental results demonstrate the performance of our new solar-powered WSN.

  20. Report of the NASA Ad Hoc Committee on failure of high strength structural materials

    NASA Technical Reports Server (NTRS)

    Brown, W. F., Jr. (Editor)

    1972-01-01

    An analysis of structural failures that have occurred in NASA programs was conducted. Reports of 231 examples of structural failure were reviewed. Attempts were made to identify those factors which contributed to the failures, and recommendations were formulated for actions which would minimize their effects on future NASA programs. Two classes of factors were identified: (1) those associated with deficiencies in existing materials and structures technology and (2) those attributable to inadequate documentation or communication of that technology.

  1. A Review of LIDAR Radiometric Processing: From Ad Hoc Intensity Correction to Rigorous Radiometric Calibration.

    PubMed

    Kashani, Alireza G; Olsen, Michael J; Parrish, Christopher E; Wilson, Nicholas

    2015-01-01

    In addition to precise 3D coordinates, most light detection and ranging (LIDAR) systems also record "intensity", loosely defined as the strength of the backscattered echo for each measured point. To date, LIDAR intensity data have proven beneficial in a wide range of applications because they are related to surface parameters, such as reflectance. While numerous procedures have been introduced in the scientific literature, and even commercial software, to enhance the utility of intensity data through a variety of "normalization", "correction", or "calibration" techniques, the current situation is complicated by a lack of standardization, as well as confusing, inconsistent use of terminology. In this paper, we first provide an overview of basic principles of LIDAR intensity measurements and applications utilizing intensity information from terrestrial, airborne topographic, and airborne bathymetric LIDAR. Next, we review effective parameters on intensity measurements, basic theory, and current intensity processing methods. We define terminology adopted from the most commonly-used conventions based on a review of current literature. Finally, we identify topics in need of further research. Ultimately, the presented information helps lay the foundation for future standards and specifications for LIDAR radiometric calibration. PMID:26561813

  2. Inventory of Training Centers; Ad Hoc National Advisory Committee on Training Complexes. Final Report.

    ERIC Educational Resources Information Center

    Clark Univ., Worcester, MA.

    This is a report of a selective survey of training activities in the United States. Selection centered on the representative activities of a variety of institutions which served different audiences, had different goals, and different sources of funding. Most of the inventories were conducted in person by a committee member. The 14 reports are…

  3. Solving data-at-rest for the storage and retrieval of files in ad hoc networks

    NASA Astrophysics Data System (ADS)

    Knobler, Ron; Scheffel, Peter; Williams, Jonathan; Gaj, Kris; Kaps, Jens-Peter

    2013-05-01

    Based on current trends for both military and commercial applications, the use of mobile devices (e.g. smartphones and tablets) is greatly increasing. Several military applications consist of secure peer to peer file sharing without a centralized authority. For these military applications, if one or more of these mobile devices are lost or compromised, sensitive files can be compromised by adversaries, since COTS devices and operating systems are used. Complete system files cannot be stored on a device, since after compromising a device, an adversary can attack the data at rest, and eventually obtain the original file. Also after a device is compromised, the existing peer to peer system devices must still be able to access all system files. McQ has teamed with the Cryptographic Engineering Research Group at George Mason University to develop a custom distributed file sharing system to provide a complete solution to the data at rest problem for resource constrained embedded systems and mobile devices. This innovative approach scales very well to a large number of network devices, without a single point of failure. We have implemented the approach on representative mobile devices as well as developed an extensive system simulator to benchmark expected system performance based on detailed modeling of the network/radio characteristics, CONOPS, and secure distributed file system functionality. The simulator is highly customizable for the purpose of determining expected system performance for other network topologies and CONOPS.

  4. iScout low-cost ad-hoc networked sensor enhancements

    NASA Astrophysics Data System (ADS)

    Winston, Mark A.

    2007-04-01

    McQ has developed a family of state of the art miniaturized low cost unattended ground sensors (UGS). The iScout TM sensors are designed for indoor and outdoor intrusion detection and battle damage assessment. McQ has developed an enhanced version of the iScout TM sensor that is a very flexible platform capable of performing in a variety of applications. Sensors are equipped with mesh radios and integrated seismic, acoustic, infrared, and magnetic transducers. Typical sensor sizes are similar to that of a deck of playing cards. Intended for high volume production, these are tactically useful sensors that can be manufactured in high volumes at a low cost. This paper will provide an overview of the iScout TM sensor systems, features, and performance.

  5. Ad HOC Model Generation Using Multiscale LIDAR Data from a Geospatial Database

    NASA Astrophysics Data System (ADS)

    Gordon, M.; Borgmann, B.; Gehrung, J.; Hebel, M.; Arens, M.

    2015-08-01

    Due to the spread of economically priced laser scanning technology nowadays, especially in the field of topographic surveying and mapping, ever-growing amounts of data need to be handled. Depending on the requirements of the specific application, airborne, mobile or terrestrial laser scanners are commonly used. Since visualizing this flood of data is not feasible with classical approaches like raw point cloud rendering, real time decision making requires sophisticated solutions. In addition, the efficient storage and recovery of 3D measurements is a challenging task. Therefore we propose an approach for the intelligent storage of 3D point clouds using a spatial database. For a given region of interest, the database is queried for the data available. All resulting point clouds are fused in a model generation process, utilizing the fact that low density airborne measurements could be used to supplement higher density mobile or terrestrial laser scans. The octree based modeling approach divides and subdivides the world into cells of varying size and fits one plane per cell, once a specified amount of points is present. The resulting model exceeds the completeness and precision of every single data source and enables for real time visualization. This is especially supported by data compression ratios of about 90%.

  6. Ad Hoc Committee on NAEP Parent Engagement: Reaching Parents with NAEP Resources

    ERIC Educational Resources Information Center

    National Assessment Governing Board, 2012

    2012-01-01

    The National Assessment Governing Board, recognizing that National Assessment of Educational Progress (NAEP) report releases were not conveying a sense of urgency, began an initiative in May 2010 to see what the Board could do to "make a difference" in fostering concern and action about the need to improve achievement and reduce achievement gaps,…

  7. Inter-Vehicular Ad Hoc Networks: From the Ground Truth to Algorithm Design and Testbed Architecture

    ERIC Educational Resources Information Center

    Giordano, Eugenio

    2011-01-01

    Many of the devices we interact with on a daily basis are currently equipped with wireless connectivity. Soon this will be extended to the vehicles we drive/ride every day. Wirelessly connected vehicles will form a new kind of network that will enable a wide set of innovative applications ranging from enhanced safety to entertainment. To…

  8. MUSIC algorithm DoA estimation for cooperative node location in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Warty, Chirag; Yu, Richard Wai; ElMahgoub, Khaled; Spinsante, Susanna

    In recent years the technological development has encouraged several applications based on distributed communications network without any fixed infrastructure. The problem of providing a collaborative early warning system for multiple mobile nodes against a fast moving object. The solution is provided subject to system level constraints: motion of nodes, antenna sensitivity and Doppler effect at 2.4 GHz and 5.8 GHz. This approach consists of three stages. The first phase consists of detecting the incoming object using a highly directive two element antenna at 5.0 GHz band. The second phase consists of broadcasting the warning message using a low directivity broad antenna beam using 2× 2 antenna array which then in third phase will be detected by receiving nodes by using direction of arrival (DOA) estimation technique. The DOA estimation technique is used to estimate the range and bearing of the incoming nodes. The position of fast arriving object can be estimated using the MUSIC algorithm for warning beam DOA estimation. This paper is mainly intended to demonstrate the feasibility of early detection and warning system using a collaborative node to node communication links. The simulation is performed to show the behavior of detecting and broadcasting antennas as well as performance of the detection algorithm. The idea can be further expanded to implement commercial grade detection and warning system

  9. Feeding the Preschool Child: Documents Issued by PAG Ad Hoc Working Group Meetings (1969-1975).

    ERIC Educational Resources Information Center

    United Nations Industrial Development Organization, Vienna (Austria).

    This document contains six papers prepared between 1969 and 1975 by the Protein-Calorie Advisory Group (PAG) of the United Nations on topics related to the feeding of preschool children in underdeveloped countries. Among the topics covered: (1) nutrition in utero; (2) nutritional aspects of breastfeeding; (3) infant mortality rates as indicators…

  10. Adding a Design Perspective to Study Learning Environments in Higher Professional Education

    ERIC Educational Resources Information Center

    Zitter, Ilya; De Bruijn, Elly; Simons, P. Robert Jan; Cate, Th. J. Ten

    2011-01-01

    How to design learning environments leading to learning-, thinking, collaboration- and regulation skills which can be applied to transferable, knowledge oriented learning outcomes is still controversial. We studied the designs of learning environments in innovative higher professional education more closely. To characterize learning environments…

  11. Unpacking the "Value Added" Impact of Continuing Professional Education: A Multi-Method Case Study Approach.

    ERIC Educational Resources Information Center

    Smith, Jo; Topping, Annie

    2001-01-01

    A study of 14 nurses who completed a children's neuroscience course found evidence of improved knowledge and increased ability to care for neurology patients. Although the direct impact of continuing education on patient care is difficult to assess, participants' assessment of their learning and its potential to affect patient care is a valid…

  12. HEFCE's People Management Self-Assessment Tool: Ticking Boxes or Adding Value? A Case Study

    ERIC Educational Resources Information Center

    McDonald, Claire

    2009-01-01

    This article examines one specific organisational development tool in depth and uses a case study to investigate whether using the tool is more than a tick-box exercise and really can add value and help organisations to develop and improve. The People Management Self-Assessment Tool (SAT) is used to examine higher education institutions' (HEIs)…

  13. Viability study of photo-voltaic systems added to terrestrial electric vehicles

    SciTech Connect

    Rippel, W.E.

    1990-09-01

    The purpose of the following computer study is to determine the set of necessary conditions under which the addition of photo-voltaic (PV) cells to electric vehicles provides a net utility or economic benefit. Economic benefits are given the primary focus and are evaluated in terms of a payback period.

  14. Adding Families to the Homework Equation: A Longitudinal Study of Mathematics Achievement

    ERIC Educational Resources Information Center

    Van Voorhis, Frances L.

    2011-01-01

    Families, whether guided or instructed to, often become involved in their children's homework. This study examined the effects of a weekly interactive mathematics program (Teachers Involve Parents in Schoolwork-TIPS) on family involvement, emotions and attitudes, and student achievement. Students and families (N=153) from four urban elementary…

  15. Teaching Therapeutic Reasoning through the Case-Study Approach: Adding the Probabilistic Dimension.

    ERIC Educational Resources Information Center

    Hartzema, Abraham G.

    1994-01-01

    It is proposed that clinical decision making in pharmacy should integrate principles of pharmacoepidemiology, economics, and medical decision making, and that case studies provide an opportunity to use these principles in probabilistic reasoning, thereby improving self-learning, critical thinking, and therapeutic and monitoring skills. Steps in…

  16. Adding Qualitative and Mixed Methods Research to Health Intervention Studies: Interacting With Differences.

    PubMed

    Johnson, R Burke; Schoonenboom, Judith

    2016-04-01

    The purpose of this article is to explain how to improve intervention designs, such as randomized controlled trials (RCTs), in health science research using a process philosophy and theory known as dialectical pluralism (DP). DP views reality as plural and uses dialectical, dialogical, and hermeneutical approaches to knowledge construction. Using DP and its "both/and" logic, and its attempt to produce new creative syntheses, researchers on heterogeneous teams can better dialogue with qualitative and mixed methods approaches, concepts, paradigms, methodologies, and methods to improve their intervention research studies. The concept of reflexivity is utilized but is expanded when it is a component of DP. Examples of strategies for identifying, inviting, and creating divergence and integrative strategies for producing strong mixed methods intervention studies are provided and illustrated using real-life examples. PMID:26657970

  17. Dirac operator on fuzzy AdS2

    NASA Astrophysics Data System (ADS)

    Fakhri, Hossein; Imaanpur, Ali

    2003-03-01

    In this article we construct the chirality and Dirac operators on noncommutative AdS2. We also derive the discrete spectrum of the Dirac operator which is important in the study of the spectral triple associated to AdS2. It is shown that the degeneracy of the spectrum present in the commutative AdS2 is lifted in the noncommutative case. The way we construct the chirality operator is suggestive of how to introduce the projector operators of the corresponding projective modules on this space.

  18. Prevention of cerebral palsy in motor risk infants by treatment ad modum Vojta. A controlled study.

    PubMed

    Brandt, S; Lønstrup, H V; Marner, T; Rump, K J; Selmar, P; Schack, L K; d'Avignon, M; Norén, L; Arman, T

    1980-05-01

    The proposal by V. Vojta in 1974 to prevent development of cerebral palsy in "motor risk" infants by special treatment has been investigated in 11 Danish and 10 Swedish babies and compared with 30 control infants with similar risk, who were not given Vojta treatment. We found a tendency for "uncomplicated" cerebral palsy cases to accumulate in the control group, although the difference was non-significant on 1 5% level. Further controlled studies must be completed before it is possible to accept the prophylactive treatment of cerebral palsy recommended by Vojta. PMID:7376854

  19. Lexical Studies of Filipino Person Descriptors: Adding Personality-Relevant Social and Physical Attributes.

    PubMed

    Imperio, Shellah Myra; Church, A Timothy; Katigbak, Marcia S; Reyes, Jose Alberto S

    2008-06-01

    Lexical studies have focused on traits. In the Filipino language, we investigated whether additional dimensions can be identified when personality-relevant terms for social roles, statuses, and effects, plus physical attributes, are included. Filipino students (N = 496) rated themselves on 268 such terms, plus 253 markers of trait and evaluative dimensions. We identified 10 dimensions of social and physical attributes-Prominence, Uselessness, Attractiveness, Respectability, Uniqueness, Destructiveness, Presentableness, Strength, Dangerousness, and Charisma. Most of these dimensions did not correspond in a one-to-one manner to Filipino or alternative trait models (Big Five, HEXACO, ML7). However, considerable redundancy was observed between the social and physical attribute dimensions and trait and evaluative dimensions. Thus, social and physical attributes communicate information about personality traits, and vice-versa. PMID:19779603

  20. Lexical Studies of Filipino Person Descriptors: Adding Personality-Relevant Social and Physical Attributes

    PubMed Central

    Imperio, Shellah Myra; Church, A. Timothy; Katigbak, Marcia S.; Reyes, Jose Alberto S.

    2009-01-01

    Lexical studies have focused on traits. In the Filipino language, we investigated whether additional dimensions can be identified when personality-relevant terms for social roles, statuses, and effects, plus physical attributes, are included. Filipino students (N = 496) rated themselves on 268 such terms, plus 253 markers of trait and evaluative dimensions. We identified 10 dimensions of social and physical attributes—Prominence, Uselessness, Attractiveness, Respectability, Uniqueness, Destructiveness, Presentableness, Strength, Dangerousness, and Charisma. Most of these dimensions did not correspond in a one-to-one manner to Filipino or alternative trait models (Big Five, HEXACO, ML7). However, considerable redundancy was observed between the social and physical attribute dimensions and trait and evaluative dimensions. Thus, social and physical attributes communicate information about personality traits, and vice-versa. PMID:19779603

  1. Adding a New Dimension to the Study of Calcareous Plankton Response to Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Oakes, R. L.; Urbanski, J. M.; Bralower, T. J.

    2014-12-01

    Anthropogenic activities are increasing atmospheric carbon dioxide concentrations at unprecedented rates. This carbon dioxide dissolves in the ocean causing both the pH and the concentration of carbonate ions to decrease. These chemical changes make it less energetically viable for calcareous organisms to form shells. This study focuses on a particularly important group of organisms; calcareous plankton, namely planktonic foraminifera and pteropods. These organisms lie at low trophic levels and therefore their demise could cause the total collapse of the marine food chain as we know it. The Pleistocene is defined by glacial-interglacial cycles with lower atmospheric CO2 concentrations (180 ppm) during glacials and higher concentrations (280 ppm) during interglacials. These fluctuations provide an ancient experiment assessing the response of planktonic foraminifera and pteropods to changing ocean chemistry. Measurements of planktonic foraminiferal tests over glacial-interglacial cycles (e.g. Broecker et al., 2003) show that shell weight increases as atmospheric CO2 decreases. We take this investigation one step further by observing individual plankton shells in a nano-CT (computed tomography) scanner which provides extraordinarily detailed three-dimensional images. These images enable us to determine detailed variations in test wall thickness and test volume, as well as ontogenetic changes in shell morphology as a response to changing atmospheric carbon dioxide. One of the key aspects of our investigation is that pteropods and planktonic foraminifera are studied collectively. This allows us to assess the differential impact of ocean acidification on aragonite and calcite. In our presentation, we illustrate the CT technique and present preliminary results from a downhole investigation of the Pleistocene from Ocean Drilling Program Site 1002 in the Cariaco Basin. In the future the nano-CT scanning method can be used to evaluate the detailed morphological response of

  2. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    NASA Astrophysics Data System (ADS)

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Davila, Jesus; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio

    2015-07-01

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e'n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides 232Th, 238U and 237Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  3. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    SciTech Connect

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio; Davila, Jesus

    2015-07-23

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e’n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides {sup 232}Th, {sup 238}U and {sup 237}Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  4. The value of adding optics to ecosystem models: a case study

    NASA Astrophysics Data System (ADS)

    Fujii, M.; Boss, E.; Chai, F.

    2007-10-01

    Many ecosystem models have been developed to study the ocean's biogeochemical properties, but most of these models use simple formulations to describe light penetration and spectral quality. Here, an optical model is coupled with a previously published ecosystem model that explicitly represents two phytoplankton (picoplankton and diatoms) and two zooplankton functional groups, as well as multiple nutrients and detritus. Surface ocean color fields and subsurface light fields are calculated by coupling the ecosystem model with an optical model that relates biogeochemical standing stocks with inherent optical properties (absorption, scattering); this provides input to a commercially available radiative transfer model (Ecolight). We apply this bio-optical model to the equatorial Pacific upwelling region, and find the model to be capable of reproducing many measured optical properties and key biogeochemical processes in this region. Our model results suggest that non-algal particles largely contribute to the total scattering or attenuation (>50% at 660 nm) but have a much smaller contribution to particulate absorption (<20% at 440 nm), while picoplankton dominate the total phytoplankton absorption (>95% at 440 nm). These results are consistent with the field observations. In order to achieve such good agreement between data and model results, however, key model parameters, for which no field data are available, have to be constrained. Sensitivity analysis of the model results to optical parameters reveals a significant role played by colored dissolved organic matter through its influence on the quantity and quality of the ambient light. Coupling explicit optics to an ecosystem model provides advantages in generating: (1) a more accurate subsurface light-field, which is important for light sensitive biogeochemical processes such as photosynthesis and photo-oxidation, (2) additional constraints on model parameters that help to reduce uncertainties in ecosystem model

  5. A Solar Constant Model for Sun-climate Studies: 1600-2000AD

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Orosz, Jerome A.

    1990-01-01

    Discussed here is the solar constant model published recently (Schatten, 1988), but with a modified phasing and amplitude. This model enables the known solar constant variations to be calculated from known active region and quiet region solar parameters. The features which can be modelled are sunspots and faculae, the only two features which mark the photospheric continuum with their unusual contrast behavior. They include both the active region features (sunspots and faculae) and the quiet region features (global faculae). Although the direct influences of sunspots upon the solar constant leads to short term decreases, an opposite, nearly in phase, 11 year variation in the solar constant is modelled, thereby agreeing with the Active Cavity Radiometer Irradiance Monitor (ACRIM) and Earth Radiation Budget (ERB) secular trends observed. This opposite behavior results primarily from global faculae (polar, network, and active region). The main contributors to the global behavior are the network faculae. The model attributes the observed variations in the solar constant entirely to magnetic features in the solar atmosphere. The present model serves purely to model the secular (long term) trend in the solar constant. The model suggests a change of approx. 0.5 W/sq m for the differences between the late twentieth century solar constant and the 17th century solar constant. This supports Eddy's view that this difference could give rise to the glacial increase during the little ice age of the 17th century. Important for present day climate studies, is that it shows the recent peak activity (peaking in 1958) is associated with an atypically high value of the solar constant, with respect to the past few hundred years.

  6. Studies of Nondefective Adenovirus 2-Simian Virus 40 Hybrid Viruses III. Base Composition, Molecular Weight, and Conformation of the Ad2+ND1 Genome

    PubMed Central

    Crumpacker, Clyde S.; Henry, Patrick H.; Kakefuda, Tuyoski; Rowe, Wallace P.; Levin, Myron J.; Lewis, Andrew M.

    1971-01-01

    The nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid virus, Ad2+ND1, differs from the defective Ad-SV40 hybrid populations previously described, in that this hybrid virus can replicate without the aid of nonhybrid adenovirus helper. Consequently, the deoxyribonucleic acid (DNA) from this virus, which can be obtained free of nonhybrid adenovirus DNA, is well suited for biophysical studies on Ad-SV40 hybrid DNA. Such studies have been performed and demonstrate Ad2+ND1 DNA to have a buoyant density (1.715 g/cm3) and thermal denaturation profile (Tm = 75.1 C) almost identical with nonhybrid Ad2 DNA. Furthermore, its molecular weight, as determined by analytical zone sedimentation and electron microscopy, was 22 × 106 to 25 × 106 daltons, which is also very similar to that determined for Ad2. Electron micrographs showed all of the hybrid molecules to be double-stranded and linear. By using this determination of the molecular weight of Ad2+ND1 DNA and assuming that 1% of this molecule consists of covalently linked SV40 DNA (see companion paper), we calculate that the hybrid DNA molecule contains 220 × 103 to 250 × 103 daltons of SV40 DNA, or the equivalent of one-tenth of the SV40 genome. PMID:4323710

  7. The efficacy of extended-release levomilnacipran in moderate to severe major depressive disorder: secondary and post-hoc analyses from a randomized, double-blind, placebo-controlled study.

    PubMed

    Montgomery, Stuart A; Mansuy, Lucilla; Ruth, Adam C; Li, Dayong; Gommoll, Carl

    2014-01-01

    Levomilnacipran (1S, 2R-milnacipran) is a potent and selective serotonin and norepinephrine reuptake inhibitor that is Food and Drug Administration approved for once-daily treatment of major depressive disorder in adults. Secondary and post-hoc analyses were carried out on data from a positive 10-week, randomized, double-blind, placebo-controlled, parallel-group, multicenter, proof-of-concept trial (EudraCT Number: 2006-002404-34) on 75 or 100 mg/day levomilnacipran extended release (ER). Included outpatients (18-70 years) met the criteria for a major depressive episode. There was a statistically significant difference in favor of levomilnacipran ER versus placebo in change from baseline to week 10 on every Montgomery Åsberg Depression Rating Scale (MADRS) single item (mixed-effects model for repeated measures; P<0.05) and most Hamilton Depression Rating Scale (HAMD17) single items. Significantly more levomilnacipran ER versus placebo patients (P < 0.05) achieved 'complete' (MADRS ≤ 5; 24 vs. 10%) and 'sustained' (MADRS ≤ 10 in Weeks 4-10; 16 vs. 10%) remission, Sheehan Disability Scale (SDS) response (total score ≤ 12 and each item score ≤ 4; 52 vs. 35%) and remission (total score ≤ 6 and each item score ≤ 2; 26 vs. 17%), and combined symptomatic (MADRS) and functional (SDS) remission (19 vs. 8%). Treatment effects of similar magnitude were observed in the severe depression subgroup (MADRS ≥ 30). These results demonstrate the benefit of levomilnacipran ER over placebo for patients with symptomatic and functional impairment associated with major depressive disorder. PMID:24172160

  8. Shadows, currents, and AdS fields

    SciTech Connect

    Metsaev, R. R.

    2008-11-15

    Conformal totally symmetric arbitrary spin currents and shadow fields in flat space-time of dimension greater than or equal to four are studied. A gauge invariant formulation for such currents and shadow fields is developed. Gauge symmetries are realized by involving the Stueckelberg fields. A realization of global conformal boost symmetries is obtained. Gauge invariant differential constraints for currents and shadow fields are obtained. AdS/CFT correspondence for currents and shadow fields and the respective normalizable and non-normalizable solutions of massless totally symmetric arbitrary spin AdS fields are studied. The bulk fields are considered in a modified de Donder gauge that leads to decoupled equations of motion. We demonstrate that leftover on shell gauge symmetries of bulk fields correspond to gauge symmetries of boundary currents and shadow fields, while the modified de Donder gauge conditions for bulk fields correspond to differential constraints for boundary conformal currents and shadow fields. Breaking conformal symmetries, we find interrelations between the gauge invariant formulation of the currents and shadow fields, and the gauge invariant formulation of massive fields.

  9. Roman literary and epigraphic sources for the study of historical seismicity in Algeria circa 42-420 ad

    NASA Astrophysics Data System (ADS)

    Ferdi, Sabah; Harbi, Assia

    2014-04-01

    The seismicity of Algeria since the nineteenth century is relatively well documented. However, compared with the numerous damaging earthquakes that are documented since 1850, fewer than a dozen reports of earthquakes are listed for the pre-1850 ad period, suggesting that the historical record is missing a substantial number of earthquakes. This paper examines the use of literary and epigraphic sources relevant to the investigation of seismicity in Algeria during Roman times. We provide examples where the meager written literary record may be supplemented with appropriate archaeological and epigraphic data describing damage to ancient Roman sites. The examples show that collaboration between earth scientists and archeologists is of utility in improving the seismic record and highlights the need for further study of data sources and repositories located both inside and outside of Algeria.

  10. An analytical study of nitrogen oxides and carbon monoxide emissions in hydrocarbon combustion with added nitrogen, preliminary results

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1979-01-01

    The effect of combustor operating conditions on the conversion of fuel-bound nitrogen (FBN) to nitrogen oxides NO sub x was analytically determined. The effect of FBN and of operating conditions on carbon monoxide (CO) formation was also studied. For these computations, the combustor was assumed to be a two stage, adiabatic, perfectly-stirred reactor. Propane-air was used as the combustible mixture and fuel-bound nitrogen was simulated by adding nitrogen atoms to the mixture. The oxidation of propane and formation of NO sub x and CO were modeled by a fifty-seven reaction chemical mechanism. The results for NO sub x and CO formation are given as functions of primary and secondary stage equivalence ratios and residence times.

  11. Combination therapy with nifedipine GITS 60 mg: subanalysis of a prospective, 12-week observational study (AdADOSE)

    PubMed Central

    Motaweih, Ahmed K.; Usova, Elena; Hussain, Wajid; Dello, Ziad; Petri, Thomas

    2016-01-01

    Abstract Background: AdADOSE was a 12-week, international, observational study conducted in the Middle East and Russia where patients received nifedipine gastrointestinal therapeutic system (GITS) at a daily dose of 30, 60, or 90 mg as part of an antihypertensive combination therapy. This subgroup analysis of the AdADOSE study assesses the efficacy and tolerability of nifedipine GITS combination therapy when used specifically at the 60-mg strength. Methods: Patients with hypertension who received a daily nifedipine GITS dose of 60 mg, either at constant dose (n = 686) or up-titrated from 30 mg (n = 392), were analyzed. Target blood pressure (BP) was <140/90 mmHg (or <130/80 mmHg for those at high/very high cardiovascular risk). Results: Following nifedipine GITS combination therapy, target BP was achieved by 33.7% patients in the 60 mg group (previously untreated, 42.5%; previously treated, 32.0%) and 32.4% patients in the 30–60 mg group (previously untreated, 45.2%; previously treated, 30.7%). Mean systolic BP/diastolic BP changes were −40.3/−20.7 mmHg and −35.6/−18.5 mmHg, respectively, and were similar regardless of previous antihypertensive treatment or the number of concomitant diseases. Incidences of drug-related adverse events (AEs) were low (3.2%, 60 mg; 2.0%, 30–60 mg group), few patients discontinued because of AEs (0.6% and 1.0%, respectively), and there were no serious AEs. Conclusion: Combination therapy with nifedipine GITS 60 mg in a real-life observational setting was effective and well tolerated in hypertensive patients, with low rates of treatment-related AEs. PMID:26331311

  12. Combination analysis of neuropsychological tests and structural MRI measures in differentiating AD, MCI and control groups--the AddNeuroMed study.

    PubMed

    Liu, Yawu; Paajanen, Teemu; Zhang, Yi; Westman, Eric; Wahlund, Lars-Olof; Simmons, Andrew; Tunnard, Catherine; Sobow, Tomasz; Mecocci, Patrizia; Tsolaki, Magda; Vellas, Bruno; Muehlboeck, Sebastian; Evans, Alan; Spenger, Christian; Lovestone, Simon; Soininen, Hilkka

    2011-07-01

    To study the ability of neuropsychological tests, manual MRI hippocampal volume measures, regional volume and cortical thickness measures to identify subjects with Alzheimer's disease (AD), mild cognitive impairment (MCI), and healthy age-matched controls. Neuropsychological tests, manual hippocampal volume, automated regional volume and regional cortical thickness measures were performed in 120 AD patients, 120 MCI subjects, and 111 controls. The regional cortical thickness and volumes in MCI subjects were significantly decreased in limbic/paralimbic areas and temporal lobe compared to controls. Atrophy was much more extensive in the AD patients compared to MCI subjects and controls. The combination of neuropsychological tests and volumes revealed the highest accuracy (82% AD vs. MCI; 94% AD vs. control; 83% MCI vs. control). Adding regional cortical thicknesses into the discriminate analysis did not improve accuracy. We conclude that regional cortical thickness and volume measures provide a panoramic view of brain atrophy in AD and MCI subjects. A combination of neuropsychological tests and regional volumes are important when discriminating AD from healthy controls and MCI. PMID:19683363

  13. 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,…

  14. 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…

  15. Added value of a household-level study during an outbreak investigation of Salmonella serotype Saintpaul infections, New Mexico 2008.

    PubMed

    Boore, A L; Jungk, J; Russo, E T; Redd, J T; Angulo, F J; Williams, I T; Cheek, J E; Gould, L H

    2013-10-01

    In 2008, nationwide investigations of a Salmonella serotype Saintpaul outbreak led first to consumer warnings for Roma and red round tomatoes, then later for jalapeño and serrano peppers. In New Mexico, where there were a large number of cases but no restaurant-based clusters, the NM Department of Health and the Indian Health Service participated with CDC in individual-level and household-level case-control studies of infections in New Mexico and the Navajo Nation. No food item was associated in the individual-level study. In the household-level study, households with an ill member were more likely to have had jalapeño peppers present during the exposure period and to have reported ever having serrano peppers in the household. This report illustrates the complexity of this investigation, the limitations of traditional individual-level case-control studies when vehicles of infection are ingredients or commonly eaten with other foods, and the added value of a household-level study. PMID:23228507

  16. Added value of a household-level study during an outbreak investigation of Salmonella serotype Saintpaul infections, New Mexico 2008

    PubMed Central

    Boore, A. L.; Jungk, J.; Russo, E.T.; Redd, J.T.; Angulo, F. J.; Williams, I. T.; Cheek, J. E.; Gould, L. H.

    2015-01-01

    SUMMARY In 2008, nationwide investigations of a Salmonella serotype Saintpaul outbreak led first to consumer warnings for Roma and red round tomatoes, then later for jalapeño and serrano peppers. In New Mexico, where there were a large number of cases but no restaurant-based clusters, the NM Department of Health and the Indian Health Service participated with CDC in individual-level and household-level case-control studies of infections in New Mexico and the Navajo Nation. No food item was associated in the individual-level study. In the household-level study, households with an ill member were more likely to have had jalapeño peppers present during the exposure period and to have reported ever having serrano peppers in the household. This report illustrates the complexity of this investigation, the limitations of traditional individual-level case-control studies when vehicles of infection are ingredients or commonly eaten with other foods, and the added value of a household-level study. PMID:23228507

  17. Treatment of the mentally ill in the Chola Empire in 11th -12th centuries AD: A study of epigraphs

    PubMed Central

    Raghavan, D. Vijaya; Tejus Murthy, A. G.; Somasundaram, O.

    2014-01-01

    The paper deals with the epigraphs of the Chola emperors Veera Rajendra Deva (1063-1069 AD) and Raja Raja III (1216-1256 AD), found at the temples of Thirumukkudal and Vedaranyam, with emphasis on the treatment given to the residents of the attached hospitals with special reference to treatment of mental disorders. PMID:24891715

  18. The Poor at School in Canada; Observational Studies of Canadian Schools, Classrooms and Pupils.

    ERIC Educational Resources Information Center

    Chalmers, John W.; And Others

    The document presents 8 observational studies of interaction of the poor and the Canadian school system in an effort to gather data on inequalities in education. An ad hoc committee formed by the Canadian Teachers' Federation (CTF) asked the member organizations to undertake observational studies following 1 of 2 main types of designs: (1) an…

  19. A Comparative Study on the Uptake and Toxicity of Nickel Added in the Form of Different Salts to Maize Seedlings

    PubMed Central

    Nie, Jing; Pan, Yuqiang; Shi, Jing; Guo, Yan; Yan, Zengguang; Duan, Xiaoli; Xu, Meng

    2015-01-01

    In soil ecotoxicological studies, a toxic metal is usually added in the form of either an inorganic or organic salt with relatively high solubility. Nitrate, chloride, acetate, or sulfate are commonly considered as valid options for that aim. However, recent studies have shown that different salts of the same metal at the same cationic concentration may exhibit different toxicities to plants and soil organisms. This information should be considered when selecting data to use for developing toxicological criteria for soil environment. A comparative study was carried out to evaluate the toxicity of five nickel (Ni) salts: NiCl2, NiSO4, Ni(II)-citrate, Ni(CH3COO)2, and Ni(II)-EDTA (ethylenediaminetetraacetate), on maize seedlings. The plant metrics used were plant height, shoot and root biomass, leaf soluble sugars and starch, and the Ni contents of the shoots and roots. The results indicated that when Ni was added to the soil, toxicity varied with the selected anionic partner with the following toxicity ranking NiSO4 < Ni(CH3COO)2 < Ni(II)-citrate < NiCl2 < Ni(II)-EDTA. Taking the plant-height metric as an example, the effective concentrations for 50% inhibition (EC50) were 3148 mg·kg−1 for NiSO4, 1315 mg·kg−1 for NiCl2, and 89 mg·kg−1 for Ni(II)-EDTA. Compared with the Ni in the other salts, that in Ni(II)-EDTA was taken up the most efficiently by the maize roots and, thus, resulted in the greatest toxic effects on the plants. Nickel generally reduced leaf soluble sugars, which indicated an effect on plant carbohydrate metabolism. The outcome of the study demonstrates that different salts of the same metal have quite different ecotoxicities. Therefore, the anionic counterpart of a potentially toxic metal cation must be taken into account in the development of ecotoxicological criteria for evaluating the soil environment, and a preferred approach of leaching soil to reduce the anionic partner should also be considered. PMID:26633435

  20. A Comparative Study on the Uptake and Toxicity of Nickel Added in the Form of Different Salts to Maize Seedlings.

    PubMed

    Nie, Jing; Pan, Yuqiang; Shi, Jing; Guo, Yan; Yan, Zengguang; Duan, Xiaoli; Xu, Meng

    2015-12-01

    In soil ecotoxicological studies, a toxic metal is usually added in the form of either an inorganic or organic salt with relatively high solubility. Nitrate, chloride, acetate, or sulfate are commonly considered as valid options for that aim. However, recent studies have shown that different salts of the same metal at the same cationic concentration may exhibit different toxicities to plants and soil organisms. This information should be considered when selecting data to use for developing toxicological criteria for soil environment. A comparative study was carried out to evaluate the toxicity of five nickel (Ni) salts: NiCl₂, NiSO₄, Ni(II)-citrate, Ni(CH₃COO)₂, and Ni(II)-EDTA (ethylenediaminetetraacetate), on maize seedlings. The plant metrics used were plant height, shoot and root biomass, leaf soluble sugars and starch, and the Ni contents of the shoots and roots. The results indicated that when Ni was added to the soil, toxicity varied with the selected anionic partner with the following toxicity ranking NiSO₄ < Ni(CH₃COO)₂ < Ni(II)-citrate < NiCl₂ < Ni(II)-EDTA. Taking the plant-height metric as an example, the effective concentrations for 50% inhibition (EC50) were 3148 mg·kg(-1) for NiSO₄, 1315 mg·kg(-1) for NiCl₂, and 89 mg·kg(-1) for Ni(II)-EDTA. Compared with the Ni in the other salts, that in Ni(II)-EDTA was taken up the most efficiently by the maize roots and, thus, resulted in the greatest toxic effects on the plants. Nickel generally reduced leaf soluble sugars, which indicated an effect on plant carbohydrate metabolism. The outcome of the study demonstrates that different salts of the same metal have quite different ecotoxicities. Therefore, the anionic counterpart of a potentially toxic metal cation must be taken into account in the development of ecotoxicological criteria for evaluating the soil environment, and a preferred approach of leaching soil to reduce the anionic partner should also be considered. PMID:26633435

  1. Feasibility and Acceptability of the Informant AD8 for Cognitive Screening in Primary Healthcare: A Pilot Study

    PubMed Central

    Dong, YanHong; Tsou, Keith Yu Kei; Chen, Christopher Li-Hsian

    2014-01-01

    Objectives. The utility of informant AD8 for case finding of cognitive impairment at primary healthcare settings is unknown and therefore its feasibility and acceptability for targeted screening at a primary healthcare clinic should be investigated. Methods. The informants of older adult patients attending a primary healthcare clinic in Singapore were administered the AD8. Positive screening findings were provided to patients' primary care physicians for referrals to specialist memory clinics. The acceptability of AD8 was evaluated by collecting feedbacks from the informants and primary care physicians. Results. 205 patients and their informants were recruited. However, 6 (2.9%) informants were uncontactable, while the majority of the remaining 199 patients with completed AD8 (96.5%, n = 192) found it acceptable where 59 (29.6%) patients were deemed cognitively impaired (AD8 ≥ 2). Clinicians (100%, n = 5) found the AD8 helpful in facilitating referrals to memory clinics. However, most referral recommendations (81.4%, n = 48) were declined by patients and/or informant due to limited insight of implications of cognitive impairment. Conclusions. The AD8 can be easily administered and is well tolerated. It detected cognitive impairment in one-third of older adult patients and therefore may be useful for case finding of cognitive impairment in the primary healthcare. PMID:25548780

  2. Comparison of the electronic structure of a thermoelectric skutterudite before and after adding rattlers: an electron energy loss study.

    PubMed

    Prytz, O; Saeterli, R; Løvvik, O M; Taftø, J

    2008-08-01

    Skutterudites, with rattler atoms introduced in voids in the crystal unit cell, are promising thermoelectric materials. We modify the binary skutterudite with atomic content Co(8)P(24) in the cubic crystal unit cell by adding La as rattlers in all available voids and replacing Co by Fe to maintain charge balance, resulting in La(2)Fe(8)P(24). The intention is to leave the electronic structure unaltered while decreasing the thermal conductivity due to the presence of the rattlers. We compare the electronic structure of these two compounds by studying the L-edges of P and of the transition elements Co and Fe using electron energy loss spectroscopy (EELS). Our studies of the transition metal white lines show that the 3d electron count is similar for Co and Fe in these compounds. As elemental Fe has one electron less than Co, this supports the notion that each La atom donates three electrons. The L-edges of P in these two skutterudites are quite similar, signalling only minor differences in electronic structure. This is in reasonable agreement with density functional theory (DFT) calculations, and with our multiple scattering FEFF calculations of the near edge structure. However, our experimental plasmon energies and dielectric functions deviate considerably from predictions based on DFT calculations. PMID:18042390

  3. Study of Harris lines at the Prat de la Riba necropolis--third to fifth century AD.

    PubMed

    Berrocal-Zaragoza, Maria Isabel; Eulàlia Subirà, Maria

    2008-06-01

    Harris lines (HL) are considered a nutritional or pathological stress factor in the study of past populations. This study attempts to contribute to the knowledge of the causal agents for HL in terms of assessing the health state of the population of Tarragona in the Roman period. The presence of HL has been analyzed in 614 long bones (214 humeri, 150 femurs and 250 tibias) from 243 skeletons. No HL have been observed in humeri. The frequencies of HL in femurs are higher than 27% and in tibias more than 48%. Although no significant differences in the presence of HL is found among age categories, it seems that the causal agents of these marks acted on individuals from the age of 5, an age from which the long bones of the lower extremities are more prone to producing HL. The hardened living conditions in the Dark Age of the Roman period in Spain between the third to fifth centuries A.D. may be the cause of the high prevalence of HL in this population. PMID:18756908

  4. Preclinical pharmacology and toxicology study of Ad-hTERT-E1a-Apoptin, a novel dual cancer-specific oncolytic adenovirus

    SciTech Connect

    Qi, Yanxin; Guo, Huanhuan; Hu, Ningning; He, Dongyun; Zhang, Shi; Chu, Yunjie; Huang, Yubin; Li, Xiao; Sun, LiLi; Jin, Ningyi

    2014-10-15

    Clinical studies have demonstrated that conditionally replicating adenovirus is safe. We constructed an oncolytic adenovirus, Ad-hTERT-E1a-Apoptin, using a cancer-specific promoter (human telomerase reverse transcriptase promoter, hTERTp) and a cancer cell-selective apoptosis-inducing gene (Apoptin). Ad-hTERT-E1a-Apoptin was proven effective both in vitro and in vivo in our previous study. In this study, the preclinical safety profiles of Ad-hTERT-E1a-Apoptin in animal models were investigated. At doses of 5.0 × 10{sup 8}, 2.5 × 10{sup 9}, and 1.25 × 10{sup 10} viral particles (VP)/kg, Ad-hTERT-E1a-Apoptin had no adverse effects on mouse behavior, muscle cooperation, sedative effect, digestive system, and nervous systems, or on beagle cardiovascular and respiratory systems at 5.0 × 10{sup 8}, 2.5 × 10{sup 9}, and 1.25 × 10{sup 10} VP/kg doses. In acute toxicity tests in mice, the maximum tolerated dose > 5 × 10{sup 10} VP/kg. There was no inflammation or ulceration at the injection sites within two weeks. In repeat-dose toxicological studies, the no observable adverse effect levels of Ad-hTERT-E1a-Apoptin in rats (1.25 × 10{sup 10} VP/kg) and beagles (2.5 × 10{sup 9} VP/kg) were 62.5- and 12.5-fold of the proposed clinical dose, respectively. The anti-virus antibody was produced in animal sera. Bone marrow examination revealed no histopathological changes. Guinea pigs sensitized by three repeated intraperitoneal injections of 1.35 × 10{sup 10} VP/mL Ad-hTERT-E1a-Apoptin each and challenged by one intravenous injection of 1.67 × 10{sup 8} VP/kg Ad-hTERT-E1a-Apoptin did not exhibit any sign of systemic anaphylaxis. Our data from different animal models suggest that Ad-hTERT-E1a-Apoptin is a safe anti-tumor therapeutic agent. - Highlights: • We use the rodents and non-rodents animal models to evaluation Ad-hTERT-E1a-Apoptin. • Ad-hTERT-E1a-Apoptin is a safe anti-tumor therapeutic agent. • Demonstrate the safety and feasibility dose of injected Ad

  5. Sources of ground movement at Vesuvius before the AD 79 eruption: Evidence from contemporary accounts and archaeological studies

    NASA Astrophysics Data System (ADS)

    Marturano, Aldo

    2008-11-01

    Historical sources have recorded earthquake shocks, their effects and difficulties that local inhabitants experienced before the AD 79 Pompeii eruption. Archaeological studies pointed out the effects of such seismicity, and have also evidenced that several water crises were occurring at Pompeii in that period. Indeed numerous sources show that, at the time of eruption, and probably some time before, the civic aqueduct, having ceased to be supplied by the regional one, was out of order and that a new one was being built. Since Roman aqueducts were usually built with a recommended minimum mean slope of 20 cm/km and Pompeii's aqueduct sloped from the nearby Apennines toward the town, this slope could have been easily cancelled by uplift that occurred in the area even if this was only moderate. For the crustal deformations a volcanic origin is proposed and a point source model is used to explain the observations. Simple analysis of the available data suggests that the ground deformations were caused by a < 2 km 3 volumetric change at a depth of ˜ 8 km that happened over the course of several decades.

  6. Added Alkane Allows Thermal Thinning of Supramolecular Columns by Forming Superlattice-An X-ray and Neutron Study.

    PubMed

    Yen, Ming-Huei; Chaiprapa, Jitrin; Zeng, Xiangbing; Liu, Yongsong; Cseh, Liliana; Mehl, Georg H; Ungar, Goran

    2016-05-11

    We report a columnar superlattice formed by blends of dendron-like Li 3,4,5-tris(n-alkoxy)benzoates with n-alkanes. Without the alkane, the wedge-shaped molecules form liquid crystal columns with 3 dendrons in a supramolecular disk. The same structure exists in the blend, but on heating one dendron is expelled from the disks in every third column and is replaced by the alkane. This superlattice of unequal columns is confirmed by complementary X-ray and neutron diffraction studies. Lateral thermal expansion of dendrons normally leads to the expulsion of excess molecules from the column, reducing the column diameter. However, in the already narrow columns of pure Li salt, expulsion of one of only three dendrons in a disk is not viable. The added alkane facilitates the expulsion, as it replaces the missing dendron. Replacing the alkane with a functional compound can potentially lead to active nanoarrays with relatively large periodicity by using only small molecules. PMID:27101731

  7. Ultrasonic Elastography Research Based on a Multicenter Study: Adding Strain Ratio after 5-Point Scoring Evaluation or Not

    PubMed Central

    Yao, Ji-Yi; Li, Lu-Jing; Peng, Yu-lan; Wang, Yi; Liu, Li-sha; Xiao, Ying; Liu, Shou-jun; Wu, Chang-jun; Jiang, Yu-xin; Parajuly, Shyam Sundar; Xu, Ping; Hao, Yi; Li, Jing; Luo, Bao-Ming; Zhi, Hui

    2016-01-01

    Background This study aimed to confirm whether strain ratio should be added after evaluation of lesions with 5-point elasticity scoring for differentiating benign and malignant breast lesions on ultrasonographic elastography(UE). Materials and Methods From June 2010 to March 2012, 1080 consecutive female patients with breast lesions were recruited into a multicenter retrospective study, which involved 8 centers across China. Each institutional ethic review board approved the study, and all the patients gave written informed consent. All the patients underwent the UE procedure and the strain ratios were calculated and the final diagnosis was made by histological findings. The sensitivity, specificity, accuracy, PPV and NPV were calculated for each of the two evaluation systems and the areas under the ROC curve were compared. Results The strain ratios of benign lesions (mean, 2.6±2.0) and malignant lesions (mean,7.9±5.8) were significantly different (p <0.01). When the cutoff point was 3.01, strain ratio method had 79.8% sensitivity, 82.8% specificity, and 81.3% accuracy, while the 5-point scoring method had 93.1% sensitivity, 73.0% specificity, and 76.8% accuracy. The areas under the ROC curve with the strain ratio method and 5-point scoring method were 0.863 and 0.865, respectively(p>0.05). The strain ratio method shows better a diagnosis performance of the lesions with elasticity score 3 and 4. Conclusions Although the two UE methods have similar diagnostic performance, separate calculation of the strain ratios seems compulsory, especially for the large solid breast lesions and the lesions with elasticity score 3 and 4. PMID:26863208

  8. A randomized, controlled, pilot study of acamprosate added to escitalopram in adults with major depressive disorder and alcohol use disorder.

    PubMed

    Witte, Janet; Bentley, Kate; Evins, Anne Eden; Clain, Alisabet J; Baer, Lee; Pedrelli, Paola; Fava, Maurizio; Mischoulon, David

    2012-12-01

    We sought to examine the efficacy and safety of acamprosate augmentation of escitalopram in patients with concurrent major depressive disorder (MDD) and alcohol use disorders. Twenty-three adults (43% female; mean ± SD age, 46 ± 14 years) were enrolled and received 12 weeks of treatment with psychosocial support; escitalopram, 10 to 30 mg/d; and either acamprosate, 2000 mg/d (n = 12), or identical placebo (n = 11). Outcomes included change in clinician ratings of depressive symptoms, MDD response and remission rates, changes in frequency and intensity of alcohol use, retention rates, and adverse events. Twelve subjects (acamprosate, n = 7; placebo, n = 5) completed the study. There was significant mean reduction in ratings of depressive symptoms from baseline in both treatment arms (P < 0.05), with no significant difference between the groups. Those in the acamprosate group had a 50% MDD response rate and a 42% remission rate, whereas those in the placebo arm had a 36% response and remission rate (not significant). Those assigned to acamprosate had significant reduction in number of drinks per week and drinks per month during the trial, whereas those assigned to placebo demonstrated no significant change in any alcohol use parameter, but the between-group difference was not significant. There were no significant associations between change in depressive symptoms and change in alcohol use. Attrition rates did not differ significantly between the 2 arms. Acamprosate added to escitalopram in adults with MDD and alcohol use disorders was associated with reduction in the frequency of alcohol use. The present study was not powered to detect superiority versus placebo. Further study in a larger sample is warranted. PMID:23131884

  9. A study of π- and ρ- mesons with a non-perturbative approach

    NASA Astrophysics Data System (ADS)

    Bermudez, Rocio; Cobos-Martnez, J. J.; Tejeda-Yeomans, M. E.

    2015-11-01

    In this poster, we give a summary of work in progress regarding the study of meson's PDAs. We explore the consequences of a momentum-independent interaction as an ad-hoc tool to rebuild the pion distribution amplitude (PDA). The PDA is obtained through its moments using the Schwinger-Dyson formalism within QCD in the rainbow-ladder approximation.

  10. Asymptotically AdS spacetimes with a timelike Kasner singularity

    NASA Astrophysics Data System (ADS)

    Ren, Jie

    2016-07-01

    Exact solutions to Einstein's equations for holographic models are presented and studied. The IR geometry has a timelike cousin of the Kasner singularity, which is the less generic case of the BKL (Belinski-Khalatnikov-Lifshitz) singularity, and the UV is asymptotically AdS. This solution describes a holographic RG flow between them. The solution's appearance is an interpolation between the planar AdS black hole and the AdS soliton. The causality constraint is always satisfied. The entanglement entropy and Wilson loops are discussed. The boundary condition for the current-current correlation function and the Laplacian in the IR is examined. There is no infalling wave in the IR, but instead, there is a normalizable solution in the IR. In a special case, a hyperscaling-violating geometry is obtained after a dimensional reduction.

  11. Geospatial modeling approach to monument construction using Michigan from A.D. 1000–1600 as a case study

    PubMed Central

    Howey, Meghan C. L.; Palace, Michael W.; McMichael, Crystal H.

    2016-01-01

    Building monuments was one way that past societies reconfigured their landscapes in response to shifting social and ecological factors. Understanding the connections between those factors and monument construction is critical, especially when multiple types of monuments were constructed across the same landscape. Geospatial technologies enable past cultural activities and environmental variables to be examined together at large scales. Many geospatial modeling approaches, however, are not designed for presence-only (occurrence) data, which can be limiting given that many archaeological site records are presence only. We use maximum entropy modeling (MaxEnt), which works with presence-only data, to predict the distribution of monuments across large landscapes, and we analyze MaxEnt output to quantify the contributions of spatioenvironmental variables to predicted distributions. We apply our approach to co-occurring Late Precontact (ca. A.D. 1000–1600) monuments in Michigan: (i) mounds and (ii) earthwork enclosures. Many of these features have been destroyed by modern development, and therefore, we conducted archival research to develop our monument occurrence database. We modeled each monument type separately using the same input variables. Analyzing variable contribution to MaxEnt output, we show that mound and enclosure landscape suitability was driven by contrasting variables. Proximity to inland lakes was key to mound placement, and proximity to rivers was key to sacred enclosures. This juxtaposition suggests that mounds met local needs for resource procurement success, whereas enclosures filled broader regional needs for intergroup exchange and shared ritual. Our study shows how MaxEnt can be used to develop sophisticated models of past cultural processes, including monument building, with imperfect, limited, presence-only data. PMID:27330115

  12. Geospatial modeling approach to monument construction using Michigan from A.D. 1000-1600 as a case study.

    PubMed

    Howey, Meghan C L; Palace, Michael W; McMichael, Crystal H

    2016-07-01

    Building monuments was one way that past societies reconfigured their landscapes in response to shifting social and ecological factors. Understanding the connections between those factors and monument construction is critical, especially when multiple types of monuments were constructed across the same landscape. Geospatial technologies enable past cultural activities and environmental variables to be examined together at large scales. Many geospatial modeling approaches, however, are not designed for presence-only (occurrence) data, which can be limiting given that many archaeological site records are presence only. We use maximum entropy modeling (MaxEnt), which works with presence-only data, to predict the distribution of monuments across large landscapes, and we analyze MaxEnt output to quantify the contributions of spatioenvironmental variables to predicted distributions. We apply our approach to co-occurring Late Precontact (ca. A.D. 1000-1600) monuments in Michigan: (i) mounds and (ii) earthwork enclosures. Many of these features have been destroyed by modern development, and therefore, we conducted archival research to develop our monument occurrence database. We modeled each monument type separately using the same input variables. Analyzing variable contribution to MaxEnt output, we show that mound and enclosure landscape suitability was driven by contrasting variables. Proximity to inland lakes was key to mound placement, and proximity to rivers was key to sacred enclosures. This juxtaposition suggests that mounds met local needs for resource procurement success, whereas enclosures filled broader regional needs for intergroup exchange and shared ritual. Our study shows how MaxEnt can be used to develop sophisticated models of past cultural processes, including monument building, with imperfect, limited, presence-only data. PMID:27330115

  13. 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.

  14. 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)…

  15. 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…

  16. Ondansetron and simvastatin added to treatment as usual in patients with schizophrenia: study protocol for a randomized controlled trial

    PubMed Central

    2013-01-01

    Background Negative symptoms and cognitive deficits are two partially-related features of schizophrenia which have a major negative impact on social function and objective quality of life. Standard drug treatments have little impact on either. There is some evidence that anti-inflammatory treatment may have beneficial effects in schizophrenia and major depression. Statins are cholesterol-lowering agents that have been found to be anti-inflammatory agents and are also known to decrease C-reactive protein (CRP). Ondansetron is a serotonin (5-HT3) receptor antagonist widely used to prevent nausea and vomiting in patients receiving chemotherapy for cancer. Small studies have suggested that ondansetron is effective as an adjunct drug in improving the symptoms of schizophrenia. Methods/design This is a two center, six-month, double-blind placebo controlled, factorial design study of ondansetron and/or simvastatin added to treatment as usual for patients suffering from schizophrenia, schizoaffective disorder, psychosis not otherwise specified or schizophreniform disorder. This will be a 2 × 2 design, with 54 patients in each cell, giving a total of 216 patients over three years. There will be a screening, a randomization and seven follow-up visits. Full clinical and neurocognitive assessments will be carried out at baseline (randomization), 14 weeks and at 26 weeks, while the positive and negative syndrome scale (PANSS), pill count and side effects checklist will be carried out at every visit. Simvastatin will be started at 20 mg once daily (OD), this will be increased to 40 mg after four weeks. Ondansetron will be administered in an 8 mg dose. Discussion Anti-inflammatory treatments have been shown to have some beneficial effects in schizophrenia. Both simvastatin and ondansetron provide some evidence of a reduction in symptoms compared to treatment as usual. The aim of this study is to establish the degree of improvement in negative symptoms with the addition of

  17. MW-class 800 MeV/n H2+ SC-cyclotron for ADS application, design and study goals

    SciTech Connect

    Meot F.; Calabretta, L.; Calanna, A.; Roser, T.; Weng, B.

    2012-05-20

    This paper addresses an attempt to start investigating the use of the Superconducting Ring Cyclotron (SRC) developed for DAE{delta}ALUS experiment for ADS application [1], focusing on the magnet design and its implication for lattice parameters and dynamic aperture performance.

  18. Integrated Study of AD-Net Mie-Lidar Network and Data Assimilated CTM for Asian Dust Epidemiology in Japan

    NASA Astrophysics Data System (ADS)

    Shimizu, Atsushi; Nishizawa, Tomoaki; Sugimoto, Nobuo; Matsui, Ichiro; Kobayashi, Hiroshi; Maki, Takashi; Sekiyama, Thomas T.; Kanatani, Kumiko

    2016-06-01

    Mie-scattering lidar data are going to be incorporated into data assimilation in chemical transport model to represent more reliable / useful horizontal distribution of Asian dust over Japan. The result is utilized in an epidemiology which surveys effect of Asian dust to human health. Wider application of AD-Net is expected in the field of environmental researches.

  19. A Value-Added Study of the Impact of Science Curriculum Reform Using the National Pupil Database

    ERIC Educational Resources Information Center

    Bell, Jacqueline; Donnelly, Jim; Homer, Matt; Pell, Godfrey

    2009-01-01

    This article compares the examination performance of students following General Certificate of Secondary Education Applied Science and Double Award science on a value-added basis. It uses data from the National Pupil Database, which are analysed by a variety of methods, including multilevel modelling. It argues that the claims made within Office…

  20. Scattering States in AdS/CFT

    SciTech Connect

    Fitzpatrick, A.Liam; Kaplan, Jared; /SLAC

    2012-02-14

    We show that suitably regulated multi-trace primary states in large N CFTs behave like 'in' and 'out' scattering states in the flat-space limit of AdS. Their transition matrix elements approach the exact scattering amplitudes for the bulk theory, providing a natural CFT definition of the flat space S-Matrix. We study corrections resulting from the AdS curvature and particle propagation far from the center of AdS, and show that AdS simply provides an IR regulator that disappears in the flat space limit.

  1. Dietary protein-to-carbohydrate ratio and added sugar as determinants of excessive gestational weight gain: a prospective cohort study

    PubMed Central

    Maslova, Ekaterina; Halldorsson, Thorhallur I; Astrup, Arne; Olsen, Sjurdur F

    2015-01-01

    Objective To examine the relation between the protein:carbohydrate (P/C) ratio and added sugar intake in pregnancy and gestational weight gain (GWG). Design A prebirth cohort including 103 119 pregnancies enrolled between 1996 and 2003. Setting All women in Denmark were eligible to participate if they spoke Danish and were planning to carry to term.The pregnant women were recruited and enrolled during their first antenatal visit (6–10 weeks of gestation). Participants Participants included women with live-born singletons and complete data on dietary intake and GWG, leaving 46 262 women for the analysis. Exposure Macronutrient intake was quantified using a validated food frequency questionnaire administered in the 25th week of gestation. The P/C ratio and added sugar intake were examined in quintiles. Primary outcome measures GWG was based on self-reported weight in gestational weeks 12 and 30 and defined as gain in g/week. We used multivariable linear regression, including adjusting for pre-pregnancy body mass index, to calculate relative change in GWG and 95% CI. Results Average GWG was 471(224) g/week. The adjusted weight gain was 16 g/week lower (95% CI 9 to 22, p for trend <0.001) in the highest (Q5) versus lowest (Q1) quintile of the P/C ratio (∼3% average reduction across the entire pregnancy). Weight gain for those with >20%E vs <12%E from protein was 36 g/week lower (95% CI 20 to 53, p for trend <0.0001; ∼8% average reduction). A high P/C ratio was inversely related to intake of added sugars. Added sugar consumption was strongly associated with GWG (Q5 vs Q1: 34, 95% CI 28 to 40 g/week, p for trend <0.0001). Conclusions A high P/C ratio was associated with reduced GWG. This association appeared to be partly driven by a decrease in intake of added sugar. These results are consistent with randomised trials in non-pregnant participants. A dietary intervention targeting an increased P/C ratio with emphasis on reducing added sugar can

  2. adLIMS: a customized open source software that allows bridging clinical and basic molecular research studies

    PubMed Central

    2015-01-01

    Background Many biological laboratories that deal with genomic samples are facing the problem of sample tracking, both for pure laboratory management and for efficiency. Our laboratory exploits PCR techniques and Next Generation Sequencing (NGS) methods to perform high-throughput integration site monitoring in different clinical trials and scientific projects. Because of the huge amount of samples that we process every year, which result in hundreds of millions of sequencing reads, we need to standardize data management and tracking systems, building up a scalable and flexible structure with web-based interfaces, which are usually called Laboratory Information Management System (LIMS). Methods We started collecting end-users' requirements, composed of desired functionalities of the system and Graphical User Interfaces (GUI), and then we evaluated available tools that could address our requirements, spanning from pure LIMS to Content Management Systems (CMS) up to enterprise information systems. Our analysis identified ADempiere ERP, an open source Enterprise Resource Planning written in Java J2EE, as the best software that also natively implements some highly desirable technological advances, such as the high usability and modularity that grants high use-case flexibility and software scalability for custom solutions. Results We extended and customized ADempiere ERP to fulfil LIMS requirements and we developed adLIMS. It has been validated by our end-users verifying functionalities and GUIs through test cases for PCRs samples and pre-sequencing data and it is currently in use in our laboratories. adLIMS implements authorization and authentication policies, allowing multiple users management and roles definition that enables specific permissions, operations and data views to each user. For example, adLIMS allows creating sample sheets from stored data using available exporting operations. This simplicity and process standardization may avoid manual errors and

  3. Smeared antibranes polarise in AdS

    NASA Astrophysics Data System (ADS)

    Gautason, Fridrik Freyr; Truijen, Brecht; Van Riet, Thomas

    2015-07-01

    In the recent literature it has been questioned whether the local backreaction of antibranes in flux throats can induce a perturbative brane-flux decay. Most evidence for this can be gathered for D6 branes and D p branes smeared over 6 - p compact directions, in line with the absence of finite temperature solutions for these cases. The solutions in the literature have flat worldvolume geometries and non-compact transversal spaces. In this paper we consider what happens when the worldvolume is AdS and the transversal space is compact. We show that in these circumstances brane polarisation smoothens out the flux singularity, which is an indication that brane-flux decay is prevented. This is consistent with the fact that the cosmological constant would be less negative after brane-flux decay. Our results extend recent results on AdS7 solutions from D6 branes to AdS p+1 solutions from D p branes. We show that supersymmetry of the AdS solutions depend on p non-trivially.

  4. Ad libitum fluid intake leads to no leg swelling in male Ironman triathletes – an observational field study

    PubMed Central

    2012-01-01

    Background An association between fluid intake and limb swelling has been described for 100-km ultra-marathoners. We investigated a potential development of peripheral oedemata in Ironman triathletes competing over 3.8 km swimming, 180 km cycling and 42.2 km running. Methods In 15 male Ironman triathletes, fluid intake, changes in body mass, fat mass, skeletal muscle mass, limb volumes and skinfold thickness were measured. Changes in renal function, parameters of skeletal muscle damage, hematologic parameters and osmolality in both serum and urine were determined. Skinfold thicknesses at hands and feet were measured using LIPOMETER® and changes of limb volumes were measured using plethysmography. Results The athletes consumed a total of 8.6 ± 4.4 L of fluids, equal to 0.79 ± 0.43 L/h. Body mass, skeletal muscle mass and the volume of the lower leg decreased (p <0.05), fat mass, skinfold thicknesses and the volume of the arm remained unchanged (p >0.05). The decrease in skeletal muscle mass was associated with the decrease in body mass (p <0.05). The decrease in the lower leg volume was unrelated to fluid intake (p >0.05). Haemoglobin, haematocrit and serum sodium remained unchanged (p >0.05). Osmolality in serum and urine increased (p <0.05). The change in body mass was related to post-race serum sodium concentration ([Na+]) (r = −0.52, p <0.05) and post-race serum osmolality (r = −0.60, p <0.05). Conclusions In these Ironman triathletes, ad libitum fluid intake maintained plasma [Na+] and plasma osmolality and led to no peripheral oedemata. The volume of the lower leg decreased and the decrease was unrelated to fluid intake. Future studies may investigate ultra-triathletes competing in a Triple Iron triathlon over 11.4 km swimming, 540 km cycling and 126.6 km running to find an association between fluid intake and the development of peripheral oedemata. PMID:22937792

  5. Shift of reaction pathway by added chloride ions in the oxidation of aromatic ketones by dichloroisocyanuric acid—A kinetic study

    NASA Astrophysics Data System (ADS)

    Kumar, Y. Lakshman; Nadh, R. Venkata; Radhakrishnamurti, P. S.

    2016-03-01

    Role of added chloride ions on the shift of reaction pathway of oxidation of aromatic ketones (acetophenone, desoxybenzoin) by dichloroisocyanuric acid (DCICA) was studied in aqueous acetic acid—perchloric acid medium. Participation of enolic and protonated forms of ketones in the rate determining steps is manifested from zero and first orders with respect to the oxidant in absence and presence of added chloride ions, respectively. Positive and negative effects of acid and dielectric constant on the reaction rate were observed. The observations deduce plausible mechanisms involving (i) rate-determining formation of enol from the conjugate acid of the ketone (SH+) in the absence of added chloride ions and (ii) rapid formation of molecular chlorine species from HOCl (hydrolytic species of DCICA) in the presence of added chloride ions, which then interacts with SH+ in a rate-determining step prior to the rapid steps of product formation. The order of Arrhenius parameters substantiate the proposed plausible mechanisms based on order of reactants both in presence and absence of added chloride ions.

  6. Calorimetric study of the smectic-Ad-smectic-A2 critical point in a binary mixture of homologs

    NASA Astrophysics Data System (ADS)

    Wen, Xin; Garland, C. W.; Shashidhar, R.; Barois, P.

    1992-03-01

    High-resolution calorimetry measurements have been performed in the vicinity of the smectic-Ad-smectic-A2 (SmAd-SmA2) critical point in mixtures of 10OPCBOB and 11OPCBOB, where nOPCBOB is alkyloxyphenyl-cyanobenzyloxy benzoate. The variation of the heat capacity Cp for three near-critical mixtures with 11OPCBOB mole % X=40.7, 42.2, and 43.5 is well described by a simple power law over a temperature range as large as Tc+/-10 K. The critical exponent γ/Δ has the value 0.45+/-0.08, which agrees with neither the mean-field nor the three-dimensional Ising model. This experimental exponent value supports the theoretical prediction that the SmAd-SmA2 critical point belongs to a new universality class different from that of Ising systems. A significant distortion of the Cp(T) peak very close to its maximum was observed for all three samples. This is an intrinsic effect that is not presently well understood; it may represent a crossover behavior for samples with a concentration X slightly different from the critical value Xc.

  7. The HOMA-Adiponectin (HOMA-AD) Closely Mirrors the HOMA-IR Index in the Screening of Insulin Resistance in the Brazilian Metabolic Syndrome Study (BRAMS)

    PubMed Central

    Cassani, Roberta Soares Lara; Forti, Adriana Costa e; Pareja, José Carlos; Tambascia, Marcos Antonio; Geloneze, Bruno

    2016-01-01

    Background The major adverse consequences of obesity are associated with the development of insulin resistance (IR) and adiposopathy. The Homeostasis Model Assessment-Adiponectin (HOMA-AD) was proposed as a modified version of the HOMA1-IR, which incorporates adiponectin in the denominator of the index. Objectives To evaluate the performance of the HOMA-AD index compared with the HOMA1-IR index as a surrogate marker of IR in women, and to establish the cutoff value of the HOMA-AD. Subjects/Methods The Brazilian Metabolic Syndrome Study (BRAMS) is a cross-sectional multicenter survey. The data from 1,061 subjects met the desired criteria: 18–65 years old, BMI: 18.5–49.9 Kg/m² and without diabetes. The IR was assessed by the indexes HOMA1-IR and HOMA-AD (total sample) and by the hyperglycemic clamp (n = 49). Metabolic syndrome was defined using the IDF criteria. Results For the IR assessed by the clamp, the HOMA-AD demonstrated a stronger coefficient of correlation (r = -0.64) compared with the HOMA1-IR (r = -0.56); p < 0.0001. In the ROC analysis, compared with the HOMA1-IR, the HOMA-AD showed higher values of the AUC for the identification of IR based on the clamp test (AUC: 0.844 vs. AUC: 0.804) and on the metabolic syndrome (AUC: 0.703 vs. AUC: 0.689), respectively; p < 0.001 for all. However, the pairwise comparison did not show evidence of superiority for the HOMA-AD in comparison with the HOMA1-IR in the diagnosis of IR and metabolic syndrome (p > 0.05). The optimal cutoff identified for the HOMA-AD for the diagnosis of IR was 0.95. Conclusions The HOMA-AD index was demonstrated to be a useful surrogate marker for detecting IR among adult women and presented a similar performance compared with the HOMA1-IR index. These results may assist physicians and researchers in determining which method to use to evaluate IR in light of the available facilities. PMID:27490249

  8. Houston, We Have a Problem: Studying the SAS Education Value-Added Assessment System (EVAAS) from Teachers' Perspectives in the Houston Independent School District (HISD)

    ERIC Educational Resources Information Center

    Collins, Clarin

    2012-01-01

    This study examined the intended and unintended consequences associated with the Education Value-Added Assessment System (EVAAS) as perceived and experienced by teachers in the Houston Independent School District (HISD). To evaluate teacher effectiveness, HISD is using EVAAS for high-stakes consequences more than any other district or state in the…

  9. Nominal group technique-elicited barriers and facilitators to following the Dietary Guidelines for solid fats and added sugars in children: The HEALTH Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The US population has a high intake of discretionary solid fats and added sugars (SoFAS) which currently exceeds federal dietary recommendations. The goal of this study was to identify barriers and facilitators to following the DGA. Thirty-eight 5th grade children across six Human Nutrition Resear...

  10. [Study of physical-mechanic characteristics of prosthetic construction after their adjustment with the use of laser welding and hot metal adding].

    PubMed

    Gvetadze, R Sh; Rusanov, F S; Mikhas'kov, S V

    2011-01-01

    Study of physical-mechanic characteristics of connecting joints of beam construction after laser welding and hot metal adding was performed. Increase of microhardness of joints as well as small reduction of bending strength of prosthetic constructions was established. PMID:21983619

  11. Canadian Mathematics Education Study Group = Groupe Canadien d'etude en didactique des mathematiques. Proceedings of the 1995 Annual Meeting (Ontario, Canada, May 26-30, 1995).

    ERIC Educational Resources Information Center

    Pothier, Yvonne M., Ed.

    These proceedings contain the papers presented at the 1995 annual meeting of the Canadian Mathematics Education Study Group. Papers are organized into four sections: (1) plenary lectures; (2) working groups; (3) topic sessions; and (4) ad hoc sessions. Papers include: (1) "The Role of Epistemology in the Analysis of Teaching/Learning Relationships…

  12. The Impact of Information and Communication Technologies on Vocational Competencies and Training. Case Studies in Italy, France and Spain. Synthesis Report. CEDEFOP Panorama.

    ERIC Educational Resources Information Center

    Gatti, Mario; Gonzalez, Lazaro Garcia; Mereu, Maria Grazia; Tagliaferro, Claudio

    This study is a consolidation of the findings acquired in the course of three parallel surveys conducted in France, Italy, and Spain on the impact of new technologies in the telecommunications and administration/office sectors. Data are from an ad hoc interview questionnaire directed at the people in charge of functional areas of the firm and…

  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. PMID:24773360

  14. 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…

  15. Self-dual warped AdS3 black holes

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Ning, Bo

    2010-12-01

    We study a new class of solutions of three-dimensional topological massive gravity. These solutions can be taken as nonextremal black holes, with their extremal counterparts being discrete quotients of spacelike warped AdS3 along the U(1)L isometry. We study the thermodynamics of these black holes and show that the first law is satisfied. We also show that for consistent boundary conditions, the asymptotic symmetry generators form only one copy of the Virasoro algebra with central charge cL=(4νℓ)/(G(ν2+3)), with which the Cardy formula reproduces the black hole entropy. We compute the real-time correlators of scalar perturbations and find a perfect match with the dual conformal field theory (CFT) predictions. Our study provides a novel example of warped AdS/CFT correspondence: the self-dual warped AdS3 black hole is dual to a CFT with nonvanishing left central charge. Moreover, our investigation suggests that the quantum topological massive gravity asymptotic to the same spacelike warped AdS3 in different consistent ways may be dual to different two-dimensional CFTs.

  16. Broad Temperature Pinning Study of 15 mol.% Zr-Added (Gd, Y)-Ba-Cu-O MOCVD Coated Conductors

    SciTech Connect

    Xu, AX; Khatri, N; Liu, YH; Majkic, G; Galstyan, E; Selvamanickam, V; Chen, YM; Lei, CH; Abraimov, D; Hu, XB; Jaroszynski, J; Larbalestier, D

    2015-06-01

    BaZrO3 (BZO) nanocolumns have long been shown to be very effective for raising the pinning force F-p of REBa2Cu3Ox (REBCO, where RE = rare earth) films at high temperatures and recently at low temperatures too. We have successfully incorporated a high density of BZO nanorods into metal organic chemical vapor deposited (MOCVD) REBCO coated conductors via Zr addition. We found that, compared to the 7.5% Zr-added coated conductor, dense BZO nanorod arrays in the 15% Zr-added conductor are effective over the whole temperature range from 77 K down to 4.2 K. We attribute the substantially enhanced J(c) at 30 K to the weak uncorrelated pinning as well as the strong correlated pinning. Meanwhile, by tripling the REBCO layer thickness to similar to 2.8 mu m, the engineering critical current density J(e) at 30 K exceeds J(e) of optimized Nb-Ti wires at 4.2 K.

  17. Added sugar, sugar-sweetened foods and beverages and risk of pancreatic cancer in the NIH-AARP Diet and Health Study

    PubMed Central

    Bao, Ying; Stolzenberg-Solomon, Rachael; Jiao, Li; Silverman, Debra T.; Subar, Amy F.; Park, Yikyung; Leitzmann, Michael F.; Hollenbeck, Albert; Schatzkin, Arthur; Michaud, Dominique S.

    2012-01-01

    Background Although hyperglycemia, hyperinsulinemia and insulin resistance have been hypothesized to be involved in the development of pancreatic cancer, results from epidemiologic studies on added sugar intake are inconclusive. Objective Our objective was to investigate whether the consumption of total added sugar, sugar-sweetened foods and beverages is associated with pancreatic cancer risk. Design We prospectively examined 487922 men and women aged 50–71 years and free of cancer and diabetes in 1995–96. Total added dietary sugar intake in teaspoons per day (based on USDA’s Pyramid Servings Database) was assessed with a food frequency questionnaire. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated with adjustment for total energy and potential confounding factors. Results During an average 7.2 years of follow-up, 1258 incident pancreatic cancer cases were ascertained. The median intakes for the lowest and highest quintiles of total added sugar intake were 12.6 g/day and 96.2 g/day. No overall increased risk of pancreatic cancer was observed in men or women with high intake of total added sugar or sugar-sweetened foods and beverages. For men and women combined, the multivariate RRs of the highest versus lowest intake categories were 0.85 (95% CI: 0.68, 1.06; P trend= 0.07) for total added sugar, 1.01 (95% CI: 0.82,1.23; P trend= 0.58) for sweets, 0.98 (95% CI: 0.82,1.18; P trend= 0.49) for dairy desserts, 1.12 (95% CI: 0.91,1.39; P trend= 0.35) for sugar added to coffee and tea, and 1.01 (95% CI: 0.77,1.31; P trend= 0.76) for sugar-sweetened soft drinks. Conclusion Our results do not support the hypothesis that consumption of added sugar, or sugar-sweetened foods and beverages is associated with overall risk of pancreatic cancer. PMID:18689380

  18. Middle Schoolers Exposed to Alcohol Ads Every Day

    MedlinePlus

    ... html Middle Schoolers Exposed to Alcohol Ads Every Day: Study Researchers say billboards, signs and TV ads ... kids typically saw two to four ads a day. Hispanic and black kids saw more ads, an ...

  19. Detection of added beet or cane sugar in maple syrup by the site-specific deuterium nuclear magnetic resonance (SNIF-NMR) method: collaborative study.

    PubMed

    Martin, Y L

    2001-01-01

    Results of a collaborative study are reported for the detection of added beet or cane sugar in maple syrup by the site-specific natural isotope fractionation-nuclear magnetic resonance (SNIF-NMR) method. The method is based on the fact that the deuterium content at specific positions of the sugar molecules is different in maple syrup from that in beet or cane sugar. The syrup is diluted with pure water and fermented; the alcohol is distilled with a quantitative yield and analyzed with a high-field NMR spectrometer fitted with a deuterium probe and fluorine lock. The proportion of ethanol molecules monodeuterated at the methyl site is recorded. This parameter (D/H)I is decreased when beet sugar is added and increased when cane sugar is added to the maple syrup. The precision of the method for measuring (D/H)I was found to be in good agreement with the values already published for the application of this method to fruit juice concentrates (AOAC Official Method 995.17). An excellent correlation was found between the percentage of added beet sugar and the (D/H)I isotopic ratio measured in this collaborative study. Consequently, all samples in which exogenous sugars were added were found to have a (D/H)I isotopic ratio significantly different from the normal value for an authentic maple syrup. By extension of what is known about plants having the C4 cycle, the method can be applied to corn sweeteners as well as to cane sugar. One limitation of the method is its reduced sensitivity when applied to specific blends of beet and cane sugars or corn sweeteners. In such case, the C13 ratio measurement (see AOAC Official Method 984.23, Corn Syrup and Cane Sugar in Maple Syrup) may be used in conjunction. PMID:11601471

  20. Detection of added beet sugar in concentrated and single strength fruit juices by deuterium nuclear magnetic resonance (SNIF-NMR method): collaborative study.

    PubMed

    Martin, G G; Wood, R; Martin, G J

    1996-01-01

    A collaborative study of the site-specific natural isotope fractionation-nuclear magnetic resonance (SNIF-NMR) method for detecting added beet sugar in fruit juices is reported. This method is complementary to the stable carbon isotope ratio analysis (SCIRA) (AOAC Official Methods 981.09 and 982.21), which can detect sugars derived from plants exhibiting C4 metabolism (corn and sugarcane). It is based on the fact that the deuterium content at specific positions of the sugar molecules is higher in fruit sugars than in beet sugar. The fruit juices are fermented, and the alcohol is distilled with a quantitative yield and analyzed with a high-yield NMR spectrometer fitted with a deuterium probe and fluorine lock. The proportion of ethanol molecules monodeuterated on the methyl site is recorded. This parameter (D/H)I is lowered when beet sugar is added to a fruit juice or concentrate. The precision of that method for measuring (D/H)I was observed to be similar to that of other isotope ratio methods: Sr values ranged from 0.19 to 0.25 ppm and SR values varied between 0.21 and 0.37 ppm. An excellent correlation was observed between the percentage of added beet sugar and the (D/H)I isotope ratio measured in this collaborative study. Consequently, all samples in which beet sugar was added were found to have a (D/H)I isotope ratio significantly below the normal value for authentic juice or concentrate of that fruit. The SNIF-NMR method for detection of added beet sugar in fruit juices has been adopted by AOAC INTERNATIONAL. PMID:8757451

  1. Tensor-Based Morphometry as a Neuroimaging Biomarker for Alzheimer’s Disease: An MRI Study of 676 AD, MCI, and Normal Subjects

    PubMed Central

    Hua, Xue; Leow, Alex D.; Parikshak, Neelroop; Lee, Suh; Chiang, Ming-Chang; Toga, Arthur W.; Jack, Clifford R.; Weiner, Michael W.; Thompson, Paul M.

    2011-01-01

    In one of the largest brain MRI studies to date, we used tensor-based morphometry (TBM) to create 3D maps of structural atrophy in 676 subjects with Alzheimer’s disease (AD), mild cognitive impairment (MCI), and healthy elderly controls, scanned as part of the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Using inverse-consistent 3D non-linear elastic image registration, we warped 676 individual brain MRI volumes to a population mean geometric template. Jacobian determinant maps were created, revealing the 3D profile of local volumetric expansion and compression. We compared the anatomical distribution of atrophy in 165 AD patients (age: 75.6 ± 7.6 years), 330 MCI subjects (74.8 ± 7.5), and 181 controls (75.9 ± 5.1). Brain atrophy in selected regions-of-interest was correlated with clinical measurements - the sum-of-boxes clinical dementia rating (CDR-SB), mini-mental state examination (MMSE), and the logical memory test scores - at voxel level followed by correction for multiple comparisons. Baseline temporal lobe atrophy correlated with current cognitive performance, future cognitive decline, and conversion from MCI to AD over the following year; it predicted future decline even in healthy subjects. Over half of the AD and MCI subjects carried the ApoE4 (apolipoprotein E4) gene, which increases risk for AD; they showed greater hippocampal and temporal lobe deficits than non-carriers. ApoE2 gene carriers - 1/6 of the normal group - showed reduced ventricular expansion, suggesting a protective effect. As an automated image analysis technique, TBM reveals 3D correlations between neuroimaging markers, genes, and future clinical changes, and is highly efficient for large-scale MRI studies. PMID:18691658

  2. Adding Memantine to Rivastigmine Therapy in Patients With Mild-to-Moderate Alzheimer's Disease: Results of a 12-Week, Open-Label Pilot Study

    PubMed Central

    Riepe, Matthias W.; Adler, Georg; Ibach, Bernd; Weinkauf, Birgit; Gunay, Ibrahim; Tracik, Ferenc

    2006-01-01

    Objective: At present, inhibition of cholines-terase is the treatment of choice for subjects with mild-to-moderate Alzheimer's disease (AD). Memantine, a noncompetitive antagonist at N-methyl-d-aspartate receptors, is currently used to treat subjects with moderate-to-severe AD. The goal of this multicenter, open-label pilot study was to investigate whether combination therapy with memantine added to rivastigmine is safe and beneficial in subjects with mild-to-moderate AD. Method: Patients with a DSM-IV diagnosis of dementia of the Alzheimer's type (N = 95), who were treated with rivastigmine (6–12 mg/day) for a maximum duration of 24 weeks prior to baseline, received memantine (5–20 mg/day) in combination with rivastigmine for 12 weeks. The primary efficacy variable was the change in the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) total score at the end of 12 weeks compared with baseline. The study was conducted between September 15, 2003, and May 27, 2004. Results: There was a statistically significant difference between baseline and week 12 for the ADAS-cog total score, showing a positive effect of combination therapy. Combination therapy did not evidence any unexpected safety concerns and was well-tolerated by most patients. Conclusion: Memantine in combination with rivastigmine appears to be safe and beneficial in patients with mild-to-moderate AD. Our results need to be confirmed in a large, long-term, randomized, double-blind, placebo-controlled clinical trial. PMID:17235381

  3. Lower vegetable protein intake and higher dietary acid load associated with lower carbohydrate intake are risk factors for metabolic syndrome in patients with type 2 diabetes: Post-hoc analysis of a cross-sectional study

    PubMed Central

    Iwase, Hiroya; Tanaka, Muhei; Kobayashi, Yukiko; Wada, Sayori; Kuwahata, Masashi; Kido, Yasuhiro; Hamaguchi, Masahide; Asano, Mai; Yamazaki, Masahiro; Hasegawa, Goji; Nakamura, Naoto; Fukui, Michiaki

    2015-01-01

    Aims/Introduction A low-carbohydrate diet based on animal sources is associated with higher all-cause mortality, whereas a vegetable-based low-carbohydrate diet is associated with lower cardiovascular disease mortality. It has been suggested that acid/base imbalance might play an important role in some cardiometabolic abnormalities. The aims of the present study were to evaluate whether carbohydrate intake is associated with quality of dietary protein and acid load, and whether these are related to metabolic syndrome in patients with type 2 diabetes. Materials and Methods The present cross-sectional study involved 149 patients with type 2 diabetes. Dietary intake was assessed using a validated self-administered diet history questionnaire. Dietary acid load was assessed by potential renal acid load and net endogenous acid production. Results Mean daily total energy intake, carbohydrate intake, animal protein intake and vegetable protein intake were 1821.5 kcal, 248.8 g, 36.1 g and 31.1 g, respectively. Carbohydrate energy/total energy was negatively correlated with animal protein energy/total energy, potential renal acid load or net endogenous acid production score, and was positively correlated with vegetable protein energy/total energy. Logistic regression analyses showed that the subgroup of patients with a lower vegetable protein energy/total energy or higher potential renal acid load or net endogenous acid production score was significantly associated with the prevalence of metabolic syndrome. Conclusions The present study showed that carbohydrate intake was associated with the quality of dietary protein and dietary acid load. Furthermore, decreased vegetable protein intake and increased dietary acid load were associated with the prevalence of metabolic syndrome. PMID:26221526

  4. Metabolomic study of plasma from female mink (Neovison vison) with low and high residual feed intake during restrictive and ad libitum feeding.

    PubMed

    Hedemann, Mette Skou; Damgaard, Birthe Marie

    2012-12-01

    Metabolite profiling may elucidate changes in metabolic pathways under various physiological or nutritional conditions. In the present study two groups of female mink characterised as having a high (16 mink) or low (14 mink) residual feed intake were investigated during restrictive and ad libitum feeding. Blood samples were collected three times during the experimental period; during restrictive feeding, and four days and three weeks after the change to ad libitum feeding. Plasma samples were subjected to liquid chromatography mass spectrometry non-targeted metabolomics. Subjecting data to principal component analysis showed that there was no grouping of the data according to the residual feed intake. In contrast, data were clearly grouped according to feeding level. Identification of the metabolites responsible for this grouping showed that the plasma level of metabolites related to mobilisation of energy was high during restrictive feeding, e.g. betaine, carnitine, and creatine. During ad libitum feeding the plasma level of metabolites that can be characterised as biomarkers of meat intake (creatinine, carnosine, 1- and 3 methylhistidine) was high. The plasma level of lysophosphatidylcholine species was highest after four days of ad libitum feeding suggesting a short term imbalance in the transport or metabolism of these metabolites when changing the feeding level. PMID:23123310

  5. 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.

    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)…

  6. Randomised comparison of zofenopril and ramipril plus acetylsalicylic acid in postmyocardial infarction patients with left ventricular systolic dysfunction: a post hoc analysis of the SMILE-4 Study in patients according to levels of left ventricular ejection fraction at entry

    PubMed Central

    Borghi, Claudio; Omboni, Stefano; Cicero, Arrigo FG; Bacchelli, Stefano; Degli Esposti, Daniela; Novo, Salvatore; Vinereanu, Dragos; Ambrosio, Giuseppe; Ambrosioni, Ettore

    2015-01-01

    Objective Conflicting evidence exists on the benefits of treating patients with coronary artery disease and preserved left ventricular ejection fraction (LVEF) with an ACE inhibitor. This retrospective analysis of the SMILE-4 Study sought to compare the efficacy of zofenopril 60 mg plus acetylsalicylic acid (ASA) versus ramipril 10 mg plus ASA 100 mg in patients with acute myocardial infarction (AMI) and heart failure, according to an impaired or preserved LVEF. Methods The primary study end point was 1-year combined occurrence of death or hospitalisation for cardiovascular causes. A preserved LVEF was defined by a baseline LVEF >40% and an impaired one by an LVEF ≤40%. Results 448 patients (63%) had preserved and 262 (37%) had impaired LVEF. The primary end point occurred in 125 patients with preserved (28%) and 106 patients with impaired LVEF (41%, p=0.001). In the first group, the rate of major cardiovascular events was significantly lower under zofenopril than under ramipril (23% vs 33%; OR and 95% CI 0.60, 0.39 to 0.91; p=0.016). This was also the case for patients with impaired LVEF, though between-group difference was not statistically significant (38% zofenopril vs 44% ramipril; OR 0.77, 0.47 to 1.26; p=0.297). LVEF values significantly (p<0.0001) increased during the follow-up in both subsets with no between-treatment differences. However, improvement rates in LVEF (increase ≥5%) were higher in patients with impaired LVEF (72% vs 61%, p=0.006). Conclusions In the SMILE-4 Study, the cardiovascular outcome of patients with post-AMI with preserved LVEF was more favourable in the zofenopril than in the ramipril treatment group. Trial registration number EudraCT Number: 2004-001150-88 (http://www.clinicaltrialsregister.eu); Italian Ministry of Health Code: GUIDOTT_III_2004_001 (https://oss-sper-clin.agenziafarmaco.it). PMID:26288740

  7. Alday-Maldacena Duality and AdS Plateau Problem

    NASA Astrophysics Data System (ADS)

    Morozov, A.

    A short summary of approximate approach to the study of minimal surfaces in AdS, based on solving Nambu-Goto equations iteratively. Today, after partial denunciation of the BDS conjecture, this looks like the only constructive approach to understanding the ways of its possible modification and thus to saving the Alday-Maldacena duality. Numerous open technical problems are explicitly formulated throughout the text.

  8. Inhibition of recombinant N-type and native high voltage-gated neuronal Ca{sup 2+} channels by AdGABA: Mechanism of action studies

    SciTech Connect

    Martinez-Hernandez, Elizabeth; Sandoval, Alejandro; Gonzalez-Ramirez, Ricardo; Zoidis, Grigoris; Felix, Ricardo

    2011-02-01

    High-voltage activated Ca{sup 2+} (Ca{sub V}) channels play a key role in the regulation of numerous physiological events by causing transient changes in the intracellular Ca{sup 2+} concentration. These channels consist of a pore-forming Ca{sub V}{alpha}{sub 1} protein and three auxiliary subunits (Ca{sub V}{beta}, Ca{sub V}{alpha}{sub 2}{delta} and Ca{sub V}{gamma}). Ca{sub V}{alpha}{sub 2}{delta} is an important component of Ca{sub V} channels in many tissues and of great interest as a drug target. It is well known that anticonvulsant agent gabapentin (GBP) binds to Ca{sub V}{alpha}{sub 2}{delta} and reduces Ca{sup 2+} currents by modulating the expression and/or function of the Ca{sub V}{alpha}{sub 1} subunit. Recently, we showed that an adamantane derivative of GABA, AdGABA, has also inhibitory effects on Ca{sub V} channels. However, the importance of the interaction of AdGABA with the Ca{sub V}{alpha}{sub 2}{delta} subunit has not been conclusively demonstrated and the mechanism of action of the drug has yet to be elucidated. Here, we describe studies on the mechanism of action of AdGABA. Using a combined approach of patch-clamp recordings and molecular biology we show that AdGABA inhibits Ca{sup 2+} currents acting on Ca{sub V}{alpha}{sub 2}{delta} only when applied chronically, both in a heterologous expression system and in dorsal root-ganglion neurons. AdGABA seems to require uptake and be acting intracellularly given that its effects are prevented by an inhibitor of the L-amino acid transport system. Interestingly, a mutation in the Ca{sub V}{alpha}{sub 2}{delta} that abolishes GBP binding did not affect AdGABA actions, revealing that its mechanism of action is similar but not identical to that of GBP. These results indicate that AdGABA is an important Ca{sub V}{alpha}{sub 2}{delta} ligand that regulates Ca{sub V} channels.

  9. Association Between Media Dose, Ad Tagging, and Changes in Web Traffic for a National Tobacco Education Campaign: A Market-Level Longitudinal Study

    PubMed Central

    Davis, Kevin C; Patel, Deesha; Rodes, Robert; Beistle, Diane

    2016-01-01

    Background In 2012, the US Centers for Disease Control and Prevention (CDC) launched Tips From Former Smokers (Tips), the first federally funded national tobacco education campaign. In 2013, a follow-up Tips campaign aired on national cable television networks, radio, and other channels, with supporting digital advertising to drive traffic to the Tips campaign website. Objective The objective of this study was to use geographic and temporal variability in 2013 Tips campaign television media doses and ad tagging to evaluate changes in traffic to the campaign website in response to specific doses of campaign media. Methods Linear regression models were used to estimate the dose-response relationship between weekly market-level television gross rating points (GRPs) and weekly Web traffic to the Tips campaign website. This relationship was measured using unique visitors, total visits, and page views as outcomes. Ad GRP effects were estimated separately for ads tagged with the Tips campaign website URL and 1-800-QUIT-NOW. Results In the average media market, an increase of 100 television GRPs per week for ads tagged with the Tips campaign website URL was associated with an increase of 650 unique visitors (P<.001), 769 total visits (P<.001), and 1255 total page views (P<.001) per week. The associations between GRPs for ads tagged with 1-800-QUIT-NOW and each Web traffic measure were also statistically significant (P<.001), but smaller in magnitude. Conclusions Based on these findings, we estimate that the 16-week 2013 Tips television campaign generated approximately 660,000 unique visitors, 900,000 total visits, and 1,390,000 page views for the Tips campaign website. These findings can help campaign planners forecast the likely impact of targeted advertising efforts on consumers’ use of campaign-specific websites. PMID:26887959

  10. The AdS particle [rapid communication

    NASA Astrophysics Data System (ADS)

    Ghosh, Subir

    2005-09-01

    In this Letter we have considered a relativistic Nambu-Goto model for a particle in AdS metric. With appropriate gauge choice to fix the reparameterization invariance, we recover the previously discussed [S. Ghosh, P. Pal, Phys. Lett. B 618 (2005) 243, arxiv:hep-th/0502192] "exotic oscillator". The Snyder algebra and subsequently the κ-Minkowski spacetime are also derived. Lastly we comment on the impossibility of constructing a non-commutative spacetime in the context of open string where only a curved target space is introduced.

  11. Observing quantum gravity in asymptotically AdS space

    NASA Astrophysics Data System (ADS)

    Emelyanov, Slava

    2015-12-01

    The question is studied of whether an observer can discover quantum gravity in the semiclassical regime. It is shown that it is indeed possible to probe a certain quantum gravity effect by employing an appropriately designed detector. The effect is related to the possibility of having topologically inequivalent geometries in the path-integral approach at the same time. A conformal field theory (CFT) state which is expected to describe the eternal anti-de Sitter (AdS) black hole in the large-N limit is discussed. It is argued under certain assumptions that the black hole boundary should be merely a patch of the entire AdS boundary. This leads then to a conclusion that that CFT state is the ordinary CFT vacuum restricted to that patch. If existent, the bulk CFT operators can behave as the ordinary semiclassical quantum field theory in the large-N limit in the weak sense.

  12. Probing crunching AdS cosmologies

    NASA Astrophysics Data System (ADS)

    Kumar, S. Prem; Vaganov, Vladislav

    2016-02-01

    Holographic gravity duals of deformations of CFTs formulated on de Sitter spacetime contain FRW geometries behind a horizon, with cosmological big crunch singularities. Using a specific analytically tractable solution within a particular single scalar truncation of {N}=8 supergravity on AdS4, we first probe such crunching cosmologies with spacelike radial geodesics that compute spatially antipodal correlators of large dimension boundary operators. At late times, the geodesics lie on the FRW slice of maximal expansion behind the horizon. The late time two-point functions factorise, and when transformed to the Einstein static universe, they exhibit a temporal non-analyticity determined by the maximal value of the scale factor ã max. Radial geodesics connecting antipodal points necessarily have de Sitter energy Ɛ ≲ ã max, while geodesics with Ɛ > ã max terminate at the crunch, the two categories of geodesics being separated by the maximal expansion slice. The spacelike crunch singularity is curved "outward" in the Penrose diagram for the deformed AdS backgrounds, and thus geodesic limits of the antipodal correlators do not directly probe the crunch. Beyond the geodesic limit, we point out that the scalar wave equation, analytically continued into the FRW patch, has a potential which is singular at the crunch along with complex WKB turning points in the vicinity of the FRW crunch. We then argue that the frequency space Green's function has a branch point determined by ã max which corresponds to the lowest quasinormal frequency.

  13. A peptidomic approach to study the contribution of added casein proteins to the peptide profile in Spanish dry-fermented sausages.

    PubMed

    Mora, Leticia; Escudero, Elizabeth; Aristoy, M-Concepción; Toldrá, Fidel

    2015-11-01

    Peptidomics is a necessary alternative in the analysis of naturally generated peptides in dry-fermented processing. The intense proteolysis occurred during the processing of dry-fermented sausages is due to the action of endopeptidases and exopeptidases from both, endogenous muscle origin and lactic acid bacteria (LAB) added in the starter. Sodium caseinate is frequently used as an additive in this type of products because of its emulsifying properties, and consequently influences the protein profile available during the proteolysis. In this study, a mass spectrometry approach has been used to determine the impact of added sodium caseinate in the final peptide profile as well as to analyse its possible influence in the presence of certain previously described casein-derived bioactive peptides. PMID:26116420

  14. Stable nitrogen isotope ratios and accumulation of various HOCs in northern Baltic aquatic food chains

    SciTech Connect

    Broman, D.; Axelman, J.; Bergqvist, P.A.; Naef, C.; Rolff, C.; Zebuehr, Y.

    1995-12-31

    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 of 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.

  15. Effects of ad placement and type on consumer responses to podcast ads.

    PubMed

    Ritter, Eric A; Cho, Chang-Hoan

    2009-10-01

    The purpose of this study was to understand the effects of podcast ad placement and podcast ad type on consumers' perceived intrusiveness, perceived irritation, attitude toward the ad, and ad avoidance. Our 2 x 2 (traditional ad vs. sponsorship by beginning vs. middle) experimental study found that sponsorships generated better consumer responses than did traditional ads and that podcast ads placed at the beginning of audio podcasts yielded better consumer responses than those placed in the middle. Implications for marketers and advertisers are discussed. PMID:19817565

  16. On information loss in AdS3/CFT2

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, A. Liam; Kaplan, Jared; Li, Daliang; Wang, Junpu

    2016-05-01

    We discuss information loss from black hole physics in AdS3, focusing on two sharp signatures infecting CFT2 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 the 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 AdS3. Our results suggest a line of inquiry towards a more precise formulation of the gravitational path integral in AdS3.

  17. AdS3: the NHEK generation

    NASA Astrophysics Data System (ADS)

    Bena, Iosif; Heurtier, Lucien; Puhm, Andrea

    2016-05-01

    It was argued in [1] that the five-dimensional near-horizon extremal Kerr (NHEK) geometry can be embedded in String Theory as the infrared region of an infinite family of non-supersymmetric geometries that have D1, D5, momentum and KK monopole charges. We show that there exists a method to embed these geometries into asymptotically- {AdS}_3× {S}^3/{{Z}}_N solutions, and hence to obtain infinite families of flows whose infrared is NHEK. This indicates that the CFT dual to the NHEK geometry is the IR fixed point of a Renormalization Group flow from a known local UV CFT and opens the door to its explicit construction.

  18. Cytoarchitecture of the human lateral occipital cortex: mapping of two extrastriate areas hOc4la and hOc4lp.

    PubMed

    Malikovic, Aleksandar; Amunts, Katrin; Schleicher, Axel; Mohlberg, Hartmut; Kujovic, Milenko; Palomero-Gallagher, Nicola; Eickhoff, Simon B; Zilles, Karl

    2016-05-01

    The microstructural correlates of the functional segregation of the human lateral occipital cortex are largely unknown. Therefore, we analyzed the cytoarchitecture of this region in ten human post-mortem brains using an observer-independent and statistically testable parcellation method to define the position and extent of areas in the lateral occipital cortex. Two new cytoarchitectonic areas were found: an anterior area hOc4la and a posterior area hOc4lp. hOc4la was located behind the anterior occipital sulcus in rostral and ventral portions of this region where it occupies the anterior third of the middle and inferior lateral occipital gyri. hOc4lp was found in caudal and dorsal portions of this region where it extends along the superior and middle lateral occipital gyri. The cytoarchitectonic areas were registered to 3D reconstructions of the corresponding brains, which were subsequently spatially normalized to the Montreal Neurological Institute reference space. Continuous probabilistic maps of both areas based on the analysis of ten brains were generated to characterize their inter-subject variability in location and size. The maps of hOc4la and hOc4lp were then used as seeds for meta-analytic connectivity modeling and quantitative functional decoding to identify their co-activation patterns and assignment to functional domains. Convergent evidence from their location, topography, size, functional domains and connectivity indicates that hOc4la and hOc4lp are the potential anatomical correlates of the functionally defined lateral occipital areas LO-1 and LO-2. PMID:25687261

  19. A Study to Test the Feasibility of Determining Whether Classified Want Ads in Daily Newspapers Are an Accurate Reflection of Local Labor Markets and of Significant Use to Employers and Job Seekers. Final Report.

    ERIC Educational Resources Information Center

    Olympus Research Corp., Salt Lake City, UT.

    The report summarizes findings of a detailed study to test the feasibility of determining whether want ads in daily newspapers are (1) an accurate reflection of local labor markets and (2) of significant use to employers and job seekers. The study found that want ads are a limited source of information about local labor markets. They are of some…

  20. Bending AdS waves with new massive gravity

    NASA Astrophysics Data System (ADS)

    Ayón-Beato, Eloy; Giribet, Gaston; Hassaïne, Mokhtar

    2009-05-01

    We study AdS-waves in the three-dimensional new theory of massive gravity recently proposed by Bergshoeff, Hohm, and Townsend. The general configuration of this type is derived and shown to exhibit different branches, with different asymptotic behaviors. In particular, for the special fine tuning m2 = ±1/(2l2), solutions with logarithmic fall-off arise, while in the range m2 > -1/(2l2), spacetimes with Schrödinger isometry group are admitted as solutions. Spacetimes that are asymptotically AdS3, both for the Brown-Henneaux and for the weakened boundary conditions, are also identified. The metric function that characterizes the profile of the AdS-wave behaves as a massive excitation on the spacetime, with an effective mass given by meff2 = m2-1/(2l2). For the critical value m2 = -1/(2l2), the value of the effective mass precisely saturates the Breitenlohner-Freedman bound for the AdS3 space where the wave is propagating on. The analogies with the AdS-wave solutions of topologically massive gravity are also discussed. Besides, we consider the coupling of both massive deformations to Einstein gravity and find the exact configurations for the complete theory, discussing all the different branches exhaustively. One of the effects of introducing the Chern-Simons gravitational term is that of breaking the degeneracy in the effective mass of the generic modes of pure New Massive Gravity, producing a fine structure due to parity violation. Another effect is that the zoo of exact logarithmic specimens becomes considerably enlarged.