Symmetric Push-Sum Protocol for decentralised aggregation

Gossip (or Epidemic) protocols have emerged as a communication and computation paradigm for large-scale networked systems. These protocols are based on randomised communication, which provides probabilistic guarantees on convergence speed and accuracy. They also provide robustness, scalability, computational and communication efficiency and high stability under disruption. This work presents a novel Gossip protocol named Symmetric Push-Sum Protocol for the computation of global aggregates (e.g., average) in decentralised and asynchronous systems. The proposed approach combines the simplicity of the push-based approach and the efficiency of the push-pull schemes. The push-pull schemes cannot be directly employed in asynchronous systems as they require synchronous paired communication operations to guarantee their accuracy. Although push schemes guarantee accuracy even with asynchronous communication, they suffer from a slower and unstable convergence. Symmetric Push- Sum Protocol does not require synchronous communication and achieves a convergence speed similar to the push-pull schemes, while keeping the accuracy stability of the push scheme. In the experimental analysis, we focus on computing the global average as an important class of node aggregation problems. The results have confirmed that the proposed method inherits the advantages of both other schemes and outperforms well-known state of the art protocols for decentralized Gossip-based aggregation.

Modeling image motion in airborne Three-Line-Array (TLA) push-broom cameras

This paper presents an image motion model for airborne three-line-array (TLA) push-broom cameras. Both aircraft velocity and attitude instability are taken into account in modeling image motion. Effects of aircraft pitch, roll, and yaw on image motion are analyzed based on geometric relations in designated coordinate systems. The image motion is mathematically modeled by image motion velocity multiplied by exposure time. Quantitative analysis to image motion velocity is then conducted in simulation experiments. The results have shown that image motion caused by aircraft velocity is space invariant while image motion caused by aircraft attitude instability is more complicated. Pitch,roll and yaw all contribute to image motion to different extents. Pitch dominates the along-track image motion and both roll and yaw greatly contribute to the cross-track image motion. These results provide a valuable base for image motion compensation to ensure high accuracy imagery in aerial photogrammetry.

Evaluation of positioning error-induced pixel shifts on satellite linear push-broom imagery

Georeferencing is one of the major tasks of satellite-borne remote sensing. Compared to traditional indirect methods, direct georeferencing through a Global Positioning System/inertial navigation system requires fewer and simpler steps to obtain exterior orientation parameters of remotely sensed images. However, the pixel shift caused by geographic positioning error, which is generally derived from boresight angle as well as terrain topography variation, can have a great impact on the precision of georeferencing. The distribution of pixel shifts introduced by the positioning error on a satellite linear push-broom image is quantitatively analyzed. We use the variation of the object space coordinate to simulate different kinds of positioning errors and terrain topography. Then a total differential method was applied to establish a rigorous sensor model in order to mathematically obtain the relationship between pixel shift and positioning error. Finally, two simulation experiments are conducted using the imaging parameters of Chang’ E-1 satellite to evaluate two different kinds of positioning errors. The experimental results have shown that with the experimental parameters, the maximum pixel shift could reach 1.74 pixels. The proposed approach can be extended to a generic application for imaging error modeling in remote sensing with terrain variation.

Effect of light-curing units on push-out fiber post bond strength in root canal dentin

The purpose of this study was to evaluate the effectiveness of different light-curing units on the bond strength (push-out) of glass fiber posts in the different thirds of the root (cervical, middle and apical) with different adhesive luting resin systems (dual-cure total-etch; dual-cured and self-etch bonding system; and dual-cure self-adhesive cements), Disks of the samples (n = 144) were used, with approximately 1 mm of thickness of 48 bovine roots restored with glass fiber posts, that were luted with resin cements photo-activated by halogen LCU (QTH, Optilux 501) and blue LED (Ultraled), with power densities of 600 and 550 mW/cm(2), respectively. A universal testing machine (MTS 810 Material Test System) was used with a 1 mm diameter steel rod at cross-head speed of 0.5 mm/min until post extrusion, with load cell of 50 kg, for evaluation of the push-out strength in the different thirds of each sample. The push-out strength values in kgf were converted to MPa and analyzed through Analysis of Variance and Tukey`s test, at significance level of 5%. The results showed that there were no statistical differences between the QTH and LED LCUs. The self-adhesive resin cement had lower values of retention. The total-etch and self-adhesive system resin cements seem to be a possible alternative for glass fiber posts cementation into the radicular canal and the LED LCU can be applied as an alternative to halogen light on photo-activation of dual-cured resin cements.

A Boolean algebra and a Banach space obtained by push-out iteration

Under the assumption that c is a regular cardinal, we prove the existence and uniqueness of a Boolean algebra B of size c defined by sharing the main structural properties that P(omega)/fin has under CH and in the N(2)-Cohen model. We prove a similar result in the category of Banach spaces. (C) 2011 Elsevier B.V. All rights reserved.

Push or pull? : The relationship between quality of care and use of complementary and alternative medicine among patients with lung cancer in Sweden

Little is known about relationships between quality of care (QoC) and use of complementary and alternative medicine (CAM) among patients with lung cancer (LC). Purpose: This study examines CAM-use among patients with LC in Sweden, associations between QoC and CAM-use among these patients, and reported aspects of LC-care perceived as particularly positive and negative by patients, as well as suggestions for improving QoC. Methods: Survey data from 94 patient members of the Swedish LC patient organization about CAM-use and QoC as measured by the instrument “Quality from the patient’s perspective” were analyzed. Results: Fifty (53%) LC-patients used CAM, with 40 of the CAM-users reporting that CAM helped them. The most common CAMs used were dietary supplements and natural remedies, followed by prayer. Significantly more patients reported using prayer and meditation for cure than was the case for other types of CAM used. Less than half the CAM-users reported having spoken with staff from the biomedical health care system about their CAM-use. Patients provided numerous suggestions for improving LC-care in a variety of areas, aiming at a more effective and cohesive care trajectory. No differences in QoC were found between CAM-users and non-CAM-users, but differences in CAM-use i.e. type of CAM, reasons for using CAM, and CAM-provider consulted could be associated with different experiences of care. Conclusions: It is important to recognize that CAM-users are not a homogeneous group but might seek different types of CAMs and CAM-providers in different situations depending on experiences of care.

Chained Negotiation for Distributed Notification Services

Distributed notification services allow consumers and publishers of notifications to interact with different notification services. However, such a distributed infrastructure makes it difficult to share notifications between consumers when consumers are allowed to specify Quality of Service levels. In this paper, we present a chained negotiation engine, enabling distributed notification services to support negotiation and to reuse existing subscriptions. We demonstrate the benefit to the system as a whole by reducing load on service providers and enabling content to be shared.

Automated Negotiation for Grid Notification Services

Notification Services mediate between information publishers and consumers that wish to subscribe to periodic updates. In many cases, however, there is a mismatch between the dissemination of these updates and the delivery preferences of the consumer, often in terms of frequency of delivery, quality, etc. In this paper, we present an automated negotiation engine that identifies mutually acceptable terms; we study its performance, and discuss its application to a Grid Notification Service. We also demonstrate how the negotiation engine enables users to control the Quality of Service levels they require.

Simulating the change from a push to pull production system

This paper will document the initial discrete-event simulation performed to study a proposed change from a push to a pull system in an existing manufacturing company. The system is characterised by five machine lines with intermediate buffers, and five major part groupings. A simulation model has been developed to mimic the flow of kanban cards in the physical system, by using a series of requests that propagate back through the facility, which the machines must respond to. The customer
demand therefore controls the level of activity in the plant. The results of the initial modelling steps will be presented in this paper, especially the impact of kanban lot size and demand variability on the output and stability of the production system, from which a set of future work is proposed.

Session initiation protocol (SIP) based event notification system architecture for telemedicine applications

Mobility service for hospital technicians involved in telemedicine applications is one of the key issues in providing more flexible and efficient in-house or remote health care services. Today, the Internet based communication has widened the opportunity of event monitoring systems in the medical field. The session initiation protocol (SIP) can work on a variety of devices and can be used to create a medical event notification system. Its adoption as the protocol of choice for third generation wireless networks allows for a robust and scalable environment. One of the advantages of SIP is that it supports personal mobility through the separation of user addressing and device addressing. In this paper, the authors propose a possible solution framework for telemedicine alert notification system based SIP-specific event notification.

Managing stakeholder 'push back', an exploratory investigation into dealing with negative cross cultural communication in a global environment

This paper addresses the issue of a current business phenomenon – ‘push back’. This phenomenon has been experienced by a number of transnational companies. It is embedded in the challenges of cross-cultural communication and involves the linkage of local culture activists with globalisation acitivists in an alliance to stop business growth. This exploratory investigation examines three multinational organisations using qualitative research. From the findings a model has been developed in an attempt to provide practitioners with a framework with which to understand ‘push back’. The complexity of combating alliances of this nature raises challenges for the current approaches to marketing and the need for a multi-stakeholder approach in cross-cultural communication is suggested.