bluuebunny/crossref_metadata_2025 huggingface dataset:
NetApp
Authors: Nguyen Tuan Loc , Jamalipour Abbas , Krief Francine , Pujolle Guy
Published: February 2011

The generalization of Internet continues to grow unabated, especially with the rapid adoption of mobile and fixed networks connecting a myriad of devices at home and in business. This allows the acquisition of more services at low costs. In the future, anyone with any kind of devices at any time will be able to access any type of service from anywhere. New rapid and profitable methods for service creation must be investigated. In traditional telecommunication networks, the intelligence of a service has been achieved for so long at the heart of the network. The Internet intermediation involves moving the intelligence toward the edge of the network. A fresh look is needed to design and develop self-organizing networks so human intervention is minimized as much as possible. In this regard, we propose the autonomic-network-based application concept: NetApp. This is an architecture in which the applications and services are not supported by a pre-existing network, but where the network itself grows out of the applications and services that end users require. The major objective of this article is to propose an architecture for the adaptive and self-organizing ambient-aware applications and services in networking.
Supporting Real-Time Service in Packet-Switched Wireless Networks
Authors: Ma Maode , Xiang Zheng
Published: February 2011

The requirement of providing real-time data service by wireless networks is a critical issue in the design of current wireless networks. Distributed Queueing Request Update Multiple Access (DQRUMA) has been proposed as a demand assignment medium access control (MAC) protocol to efficiently control the medium sharing by multiple mobile users. With the help of a packet transmission policy, DQRUMA has a potential to provide QoS service for the time-constrained burst data traffic. In this article, we study the problem of providing real-time service to fixed-size packets with or without time constraints in wireless networks. In particular, we propose a novel scheduling scheme for the DQRUMA protocol to control the packet transmission in packet-switched wireless networks. We have conducted extensive simulation experiments to evaluate the performance of the proposed algorithm and to compare its real-time performance with those of other packet transmission policies. This study proves that the new algorithm is an efficient transmission policy for the DQRUMA to support real-time service in wireless networks.
Employees' Attitudes Toward Telecommuting
Authors: Abdel-Wahab Ahmed G.
Published: February 2011

Thousands of companies today in a wide variety of industries are experiencing the benefits of allowing employees to work from their homes. Telecommuting has become a recognized and accepted work alternative for millions of Americans and has grown exponentially during the past 20 years. The main purpose of this article is to explore the attitude of Egyptian information workers toward the concept of telecommuting and to examine the relationships between such attitude and workers’ expectations of their productivity and job satisfaction if they participated in a telecommuting program. Original data were collected by using a self-administered questionnaire. A national sample of 228 Egyptian information workers in Dakahlia governorate in Egypt completed the questionnaires with usable data. The results revealed that more respondents are in favor of telecommuting than those who are not in favor of the concept and that the increase in the attitude score toward telecommuting tends to be paired with higher expectations about telecommuting productivity and satisfaction.
Multicast Copyright Protection System Based on a Trusted Soft-Engine
Authors: Pegueroles Josep , Fernandez Marcel , Rico-Novella Francisco , Soriano Miguel
Published: February 2011

One of the main problems that remains to be solved in pay-per-view Internet services is copyright protection. In Internet services such as near video on-demand, where multicast is used, watermarking can be directly applied. On the other hand, multicast fingerprinting has been seldom studied because delivering different marked content for different receivers seems a contradiction with multicast basics. In this paper we present a solution to prevent unauthorized redistribution of content in multicast scenarios. The system is based on a trusted soft-engine embedded in the receiver and co-managed by the content distributor. The trusted soft-engine is responsible for the client-side multicast key management functions. It only will allow the decryption and displaying of the actual data if it has previously inserted a fingerprinting mark with the identity of the decoder.
Fuzzy Reasoning Approach for Local Connectivity Management in Mobile Ad Hoc Networks
Authors: Natsheh Essam , Jantan Adznan B. , Khatun Sabira , Subramaniam Shamala
Published: February 2011

Routing is an important functional aspect in wireless ad hoc networks that handles discovering and maintaining the paths between nodes within a network. Due to nodes’ mobility, the efficiency of a dynamic ad hoc routing protocol depends highly on updating speed of network topology changes. To achieve continuous updated routing tables, the nodes periodically broadcast short Hello messages to their neighbors. Although benefits of these messages have been proven, many studies show some drawbacks for these messages. In this paper, we adaptively optimize the frequent needs of those messages using a fuzzy logic system. The proposed fuzzy algorithm is used to model the uncertainty measurements for updating local connectivity successfully in time. Extensive performance analysis via simulation proves the effectiveness of the proposed method to improve the accuracy of neighborhood information and, hence, overall network performance.
Network Setup for Secure Routing in Inter-Vehicle Communication Networks
Authors: Wehbi Rania , Kayssi Ayman , Chehab Ali , Dawy Zaher
Published: February 2011

In Inter-Vehicle Communication (IVC) networks, the high mobility and lack of infrastructure pose major challenges in designing secure routing protocols. In this work, we present a new secure routing protocol called SERVEN (SEcure Routing in VEhicular Networks) that can achieve near-instantaneous secure communication in IVC networks. In particular, we concentrate on the design of the network setup phase of the protocol and we present simulation results using Network Simulator version 2.28 (ns-2.28). Secure setup means the appropriate formation of a network whose nodes are aware of each other and of the right topology. This is especially important for location-based routing protocols in IVC networks.
Robust Algorithms for DOA Estimation and Adaptive Beamforming in Wireless Mobile Communications
Authors: Shubair R.M. , AlMidfa K.O. , Al-Marri A. , Al-Nuaimi M.
Published: February 2011

This paper presents a tool for the modelling, analysis and simulation of direction-of-arrival (DOA) estimation and adaptive beamforming needed in the design of smart antenna arrays for wireless mobile communications. The developed tool implements the Minimum Variance Distortionless Response (MVDR) algorithm for DOA estimation and the Least Mean Squares (LMS) algorithm for adaptive beamforming. Performance of each algorithm is investigated with respect to the variation of a number of parameters that related to the signal environment and sensor array. Results of numerical simulation are useful for the design of smart antennas systems with optimal performance. Hence, the developed simulation tool can be used to improve and accelerate the design of wireless networks. It can also be used for computer-aided learning of modern communication systems utilizing smart antenna arrays.
Simple Interference Cancellation Technique for Multicarrier DS-CDMA
Authors: Radhakrishnan R. , Shankarkumar K. R. , Jeyakumar A. Ebenezer
Published: February 2011

In this article, we propose a new scheme for multi user detection (MUD) using the parallel interference cancellation (PIC) technique. This technique provides a good complexity, latency, and performance compromise. Among spread-spectrum techniques, the most popular one is the direct sequence-code division multiple access (DS-CDMA), where each active user’s data is modulated (multiplied) by a unique code. This technique is suitable for multicarrier (MC) direct sequence-code division multiple access (DS-CDMA) systems. We offer a new scheme of soft detectors whose performance is superior to that of the other famous suboptimal detectors. On each sub carrier, instead of making hard bit decisions of the other users in the current stage and regenerating and cancelling the interference signal, a weighted sum of the soft outputs of the other users in the current stage is cancelled from the soft output of the desired user. This is the input to the next stage, then at the last stage, the interference cancelled outputs from all the subcarriers are combined (maximal ratio combining) to form the decision statistics. We derived expressions for the bit error rate (BER) on Rayleigh fading channels. Analytical results are found for different stages in the proposed PIC scheme. The simulation results show that the proposed scheme offers good interference cancellation than the other filter receiver. The complexity of this scheme grows linearly with the number of users. Moreover, this scheme is much faster than other receivers such as successive interference cancellation (SIC).
Performance Analysis of 3-Stage Cell Search Process in a WCDMA System
Authors: Mishra Shailendra , Nipur
Published: February 2011

In this article, we study the performance benefits of the cell search algorithm. The purpose of the cell search algorithm in Universal Mobile Telecommunication Systems (UMTS) is to estimate the spreading code of the serving base-station and its corresponding timing offset. We study the performance benefits of estimating multiple “code-time” hypotheses in each stage of the cell search process. In addition, we also study the effect of oversampling and nonideal sampling. The improved cell search design (CSD) proposed in this article aims to achieve faster synchronization between the mobile station (MS) and the base station (BS) and thus improves system performance, also has lower hardware utilization when compared with the third generation partnership project (3GPP)-comma free cell search design scheme under the same design constraints.
Suitability of IP telephony in the Public Switched Telephone Network (PSTN)
Authors: Kim Hak Ju
Published: February 2011

This article seeks to develop a richer understanding of the suitability of IP telephony in the Public Switched Telephony Network (PSTN) with an actual local exchange carrier (LEC)’s case and network simulation. We also performed a simple real options analysis to evaluate a telecommunications network. The underlying network and associated data were derived from our studies of an actual LEC. The preliminary result shows that an IP telephony network would save about 73% of the total link capacity of a circuit switched network and it could also carry some integrated services traffic at low incremental cost. The value of the IP telephony network was shown as positive under real options and as negative using net present value (NPV). We measured deferrable and irreversible value as well as the uncertainty value of an IP telephony network. Through this experiment, we can get inference that IP has potential for a voice carriage.
Spread Spectrum Techniques for an Intelligent Energy Meter
Authors: Suriyakala C. D. , Sakaranarayanan P. E.
Published: February 2011

The intelligent energy meter designed by us is basically a digital energy meter, which uses single-phase energy metering IC. This metered reading is brought to the database of electricity board through the” echo model”, which is identified as a suitable model for the house hold power lines among the existing power line channel models .This is followed by studies on the utilization of different robust spread spectrum techniques like code division multiplexing (CDM), Orthogonal frequency division multiplexing (OFDM) and COFDM (Combined) for data communication over the selected channel model. The results of the study are conducted, particularly in respect of bit error rate (BER) performance and spectral efficiency.
Performance of 802.11b Mesh Network Under Channel Interference for Wireless Internet
Authors: Sankaranarayanan Suresh
Published: February 2011

This article shows the performance of wireless mesh networks under channel interference for wireless Internet. The wireless mesh networks are multihop networks of wireless-router platforms. The wireless routers are typically stationary, but the clients can be mobile. A mesh network can provide multihop communication paths between wireless clients, serving as a community network or as a broadband access network for the Internet. Though no routing protocols exist for wireless mesh networknetworks, the author has tried using AODV, which has been proved effective for wireless mesh networknetworks. Although research is being done in revisiting the MAC and routing protocols for wireless mesh networknetworks, one of the major problems faced in 802.11b mesh networks is channel interference. Based on the above facts, an attempt has been made to study the performance of the 802.11b mesh network under channel interference. The performance differentials are analyzed in terms of throughput, end-to-end delay, and MAC delay. The simulations are carried out in Opnet Version 11.5 simulator
An Asymptotic Analysis of a Queuing Model for a Call Center
Authors: Kannan K. Senthamarai , Vijayalakshmi C.
Published: February 2011

This article deals with the simplest abandonment model in which the customer’s patience is exponentially distributed and the capacity of the system is unlimited. Sze (1984, 229-249) has designed a queuing model for the telephone operating system without abandonment. The most common model which supports the workforce management of the telephone centre is M/M/N/B and some special cases can be analyzed as M/M/N with Erlang distribution C’ which models out busy signals and M/M/N/N queuing model with Erlang B distribution disallow the waiting concept. Many queuing models lack the feature that impatient customers might decide to leave, before the service begins. In this article, the simplest abandonment model is considered is M/ M/N+M which includes abandonment and this model can be used to analyse, provide information which is important for the call center managers. Based on the numerical calculations and graphical representations this model can be considered as an appropriate queuing model to manage a large call center in heavy traffic with abandonment.
Performance Evaluation of Energy and Delay Aware Quality of Service (QoS) Routing Protocols in Mobile Adhoc Networks
Authors: Asokan R. , Natarajan A.M.
Published: February 2011

Mobile adhoc network (MANET) is a collection of mobile devices which form a communication network with no pre-existing wiring or infrastructure. Multiple routing protocols have been developed for MANETs. As MANETs gain popularity, their need to support real time applications is growing as well. Quality of service(QoS) provisioning is becoming a critical issue in designing mobile adhoc networks due to the necessity of providing multimedia applications.These applications have stringent QoS requirements such as throughput, end-to-end delay, and energy. Due to dynamic topology and bandwidth constraint supporting QoS is a challenging task. QoS aware routing is an important building block for QoS support. The primary goal of the QoS aware protocol is to determine the path from source to destination that satisfies the QoS requirements. This article proposes a new energy and delay aware protocols called, energy and delay aware Adhoc On demand Distance Vector Routing (EDAODV) and energy and delay aware Dynamic Source Routing(EDDSR) based on extension of AODV and DSR. Simulation results show that the proposed protocols have a better performance than AODV and DSR in terms of energy, packet delivery ratio and end-to-end delay.
Optimal Allocation of Multimedia Servers in the 3G Wireless Networks
Authors: Pendharkar Parag C.
Published: February 2011

We propose a multimedia server allocation problem in the 3G wireless networks as a generalized assignment problem (GAP) with an objective of minimizing the total multimedia applications access cost. Because the GAP is a well known NP hard problem, we use the Lagrangian relaxation (LR) heuristic to compute a lower bound on the total multimedia applications access cost. For small size problems, we solve the multimedia server allocation problem optimally and compare the optimal solution with the LR heuristic. Our results indicate that the LR heuristic provides a very tight lower bound and may be useful for estimating lower bound on the total multimedia applications access cost for a large scale problem where finding an optimal solution is very difficult.
QoS-Aware Multicast Routing for Mobile Ad Hoc Networks
Authors: Nargunam A. Shajin , Sebastian M.P.
Published: February 2011

Applications of ad hoc networks are increasing in recent years because of their ease of deployment. Mobile ad hoc networks multimedia applications require an efficient and effective quality of service-aware multicast routing scheme. Supporting quality of service in an ad hoc environment is a major challenge due to unpredictable and rapidly changing topology. In this article a novel cluster-based QoS aware multicast routing protocol (CQMRP) for mobile ad hoc network is presented. In this scheme the multicast routes are constructed in a distributed manner. Analysis shows that the control overhead generated by the proposed QoS aware multicast routing scheme is less than the other related schemes. The simulation result shows that the packet delivery ratio of the proposed scheme is better than HQMRP in higher mobility scenario. In addition to that it is highly adaptable to topology changes.
A Survey on Fuzzy Reasoning Applications for Routing Protocols in Wireless Ad Hoc Networks
Authors: Natsheh Essam
Published: February 2011

The challenge in creating a routing protocol for ad hoc networks is to design a single protocol that can adapt to the wide variety of conditions that can be present in any ad hoc network environment. The routing protocol must perform efficiently in environments in which it suffers from high nodes mobility and many wireless transmission constraints. Because it is often impossible to know in advance what environment the protocol will find itself in, and because the environment can change unpredictably, the routing protocol must be able to adapt automatically. In this paper, we survey fuzzy reasoning algorithm (FRA) as a highly adaptive algorithm used to achieve that goal. We present the various application of that algorithm to ad hoc routing protocols. In particular, the exposition includes a discussion of strength and weakness of these applications and how they can be improved.
Dynamic Evaluation of Server Placement within a Network Design Tool by using an Embedded Monte Carlo Simulator
Authors: Habib Sami J.
Published: February 2011

This article presents a Monte Carlo simulator (MCS), which is embedded within iCAD, which is a design and analysis tool that concurrently synthesizes network topology, server placement, and file allocation for application-specific networks. We formulated the three problems as a single optimization problem, where the objective is to minimize the design cost, subject to the satisfactions of the design and performance constraints. An evolutionary approach is used to search the design space. During each evolution cycle, an analytical model (network of M/M/1 queues) is used to evaluate the network topology. At the same cycle, the embedded MCS is used to evaluate the placed servers. MCS is used due to some uncertainty concerning with the requesting times of file transfer by the clients that can lead to unacceptable performance by the servers. Our experimental results have demonstrated the effectiveness of two heterogeneous analysis methodologies in evaluating the designs in a short time.
QoS Provisioning for Multimedia Applications on Ts by Adapting MPLS
Authors: Ashraf Sadia , Khan Shoab A. , Khattak Naveed S.
Published: February 2011

Multimedia applications require certain QoS guarantees to be met in order to function properly. QoS requirements for multimedia transmission include bandwidth guarantees and temporal guarantees (delay and jitter). Existing routing protocols on MANeTs are not adequate enough to deal with these necessities imposed by multimedia traffic. In this article, an adaptation of MPLS is proposed for MANeTs. M2PLS and MLDP together are employed in MANeTs to provide QoS and traffic engineering for real time multimedia traffic. These protocols are implemented and tested in the OMNeT++ network simulator. This article describes in detail the design and implementation of M2PLS and MLDP. Keywords: Multimedia traffic, MANeT, QoS, MPLS
Fairness Analysis and Improvement of Transport Layer Protocols
Authors: Tegze D. , Hosszú G. , Kovács F.
Published: February 2011

The article presents a comparison of fairness properties of different congestion control schemes. It is hard to investigate the various protocol mechanisms implemented in transport protocols; therefore a simulator called SimCast is developed for the analysis of fairness characteristics of transport protocols as well as a network traffic generator and measurement tool called SimTest. This article presents the operation and basic properties of these evaluation systems together with some simulation and measurement results. The article also presents a fairness based bandwidth control mechanism, called the Balancer method, which optimizes resource allocation of busy servers with large amount of outgoing traffic. The efficiency of this control method is presented through simulation results.
On the Impact of Network Dynamics on a Discovery Protocol for Ad-Hoc Networks
Authors: Liu Fei , Heijenk Geert
Published: February 2011

A very promising approach to discovering services and context information in ad-hoc networks is based on the use of Attenuated Bloom filters. In this paper we analyze the impact of changes in the connectivity of an ad-hoc network on this approach. We evaluate the performance of the discovery protocol while nodes appear, disappear, and move, through analytical and simulative analysis. The analytical results are shown to be accurate when node density is high. We show that an almost linear relation exists between the density of the network and the number of update messages to be exchanged. Further, in case of nodes moving, the number of messages exchanged does not increase with the speed of movement.
Models and Architecture for Autonomic Network Management
Authors: Van Wambeke N. , Armando F. , Abdelkefi A.
Published: February 2011

This paper presents a model-based framework to support the automated and adaptive deployment of communication services for QoS. The application domain targets cooperative group activities applied to military emergency operation management systems. Various models are introduced to represent the different levels of cooperation (applicative / middleware / transport). The adaptation decision process relies on structural model transformations while its enforcement is based on the dynamic composition of micro-protocols and software components. Automated deployment is performed both at the transport (i.e. UDP-TCP level) and middleware level. The architecture to support automated network management based on these models is introduced and its performance is evaluated through the use of a Java prototype.
Service Offerings for Fixed-Mobile Convergence Scenario
Authors: Harno Jarmo , Kumar K.R. Renjish , Heikkinen Mikko V.J. , Kind Mario , Monath Thomas , Von Hugo Dirk
Published: February 2011

This study demonstrates that an integrated operator can benefit from cost savings, customer retention and prevention of revenue erosion by FMC migration strategy with introduction of advanced service packages. This development is driven by increasing importance of mobile network capabilities and services, as well as the lessening gap between fixed and mobile systems, in terms of technological models and prices, resulting in greater market-pull and commercially feasible FMC offerings. FMC is expected to offer benefits for network and service operators as well as businesses and consumers. We have also analyzed the operator’s dilemma in selecting an appropriate migration strategy to exploit the benefits of cost savings and generating new revenues, while exposing oneself to the risk of substitution effects among its fixed and mobile products. The objective in this article has been to provide quantitative comparison of some strategic scenarios utilizing techno-economic case study methodology in modeling an integrated operator business in the Western European context.
Subscription Policy Control Framework for IMS-Based Networks
Authors: Nasser Nidal , Shang Ming
Published: February 2011

The Policy and Charging Control (PCC) architecture was firstly introduced in the 3GPP’s Release 7. However, the PCC has its problems. The main problems include the incapability of performing policy control with consideration of subscriber profiles and missing specification on how to organize and express the policy information. In addition, no policy control at application session establishment stage also contributes to its imperfectness. In this paper, the authors propose a subscription-based policy control framework that implements a subscription-centered approach for policy control and to enable flexible policy definitions based on the subscriber’s profile at the application level. The framework also provides functionalities of organizing the subscription data, identifying the policy, regulating the policy control process, interpreting, managing and enforcing the corresponding policies. The main objective is to qualify the subscribers and thus, enhance the network customization through defining flexible policies based on policy control requirements for different subscribers.
On Demand Bandwidth Reservation for Real-Time Traffic in Cellular IP Network using Particle Swarm Optimization
Authors: Anbar Mohammad , Vidyarthi D.P.
Published: February 2011

Cellular IP network deals with micro mobility of the mobile devices. An important challenge in wireless communication, especially in cellular IP based network, is to provide good Quality of Service (QoS) to the users in general and to the real-time users (users involved in the exchange of real-time packets) in particular. Reserving bandwidth for real time traffic to minimize the connection drop (an important parameter) is an activity often used in Cellular IP network. Particle Swarm Optimization (PSO) algorithm simulates the social behavior of a swarm or flock to optimize some characteristic parameter. PSO is effectively used to solve many hard optimization problems. The work, in this paper, proposes an on demand bandwidth reservation scheme to improve Connection Dropping Probability (CDP) in cellular IP network by employing PSO. The swarm, in the model, consists of the available bandwidth in the seven cells of the cellular IP network. The anytime bandwidth demand for real-time users is satisfied by the available bandwidth of the swarm. The algorithm, used in the model, searches for the availability of the bandwidth and reserves it in the central cell of the swarm. Eventually, it will allocate it on demand to the cell that requires it. Simulation experiments reveal the efficacy of the model.
Mobile Division Query Processing Incorporating Multiple Non-Collaborative Servers
Authors: Lim Say Ying , Taniar David , Srinivasan Bala
Published: February 2011

The demand of mobile technology is growing and mobile information services including the gathering of information and manipulating them are also becoming more critical in the world of mobile technology. These allow mobile users to download useful data, possibly from multiple sources. In this article, we introduce two basic mobile queries processing, namely: (i) mobile device side processing (MDSP), and (ii) server side processing (SSP). Our focus in this article is on performing relational division and multiple division operations using both MDSP and SSP techniques. In addition, walkthrough examples are also illustrated. A series of performance evaluation of our proposed techniques are presented and analyzed.
Period Size Self Tuning to Enhance Routing in MANETs
Authors: Abid Mohamed Amine , Belghith Abdelfettah
Published: February 2011

In this paper, the authors propose a novel routing protocol driven by an asynchronous distributed cartography gathering algorithm. Each node senses its own dynamics and chooses locally an appropriate routing period size. As such stationary nodes generate little signaling traffic; fast moving nodes choose small routing periods to mitigate the effect of their mobility. Moreover, every node integrates a self regulating process that dynamically and constantly calibrates the chosen routing period to track changes in its dynamics. The performances of this proposed routing protocol are evaluated and compared to the known Optimized Link State Routing (OLSR) protocol through extensive simulations. The paper shows that the collected network cartography maintains a validity ratio near 100% even for high node speeds. The authors illustrate that the proposed routing protocol provides around 97% routing validity while the OLSR can hardly deliver more than 60% at moderate to high speeds and workloads. Finally, the protocol provides better throughput than OLSR, reaching a 50% increase at moderate to high speeds and workloads far less end-to-end delays.
Linking the Popularity of Online Trading with Consumers’ Concerns for Reputation and Identity Theft
Authors: Smith Alan D.
Published: February 2011

Although online trading has its benefits, such as convenience and the ability to compare prices online, there are still many concerns about the integrity of the buyer, the seller and/or the online action service provider (OASP). This paper investigates these relationships via multivariate statistical analysis of a stratified sample of working professionals, resulting in 198 useable questionnaires from an initial sampling frame of over 550 professional personnel from five relatively large Pittsburgh, Pennsylvania, firms. The author found that buyers that felt feedback systems were viable were more willing to engage in online trading activities and pay a premium price for merchandise being sold by a seller with a better reputation, regardless of gender. Customers were especially concerned with the total price, including shipping cost, regardless of gender. In terms of the convenience of payment method, electronic forms were preferred in transacting online trading activities, regardless of age and gender.
A Novel Dynamic Noise-Dependent Probabilistic Algorithm for Route Discovery in MANETs
Authors: Al-Bahadili Hussein , Sabri Alia
Published: February 2011

In mobile ad hoc networks (MANETs), broadcasting is widely used in route discovery and other network services. The most widely used broadcasting algorithm is simple flooding, which aggravates a high number of redundant packet retransmissions, causing contention and collisions. Proper use of dynamic probabilistic algorithm significantly reduces the number of retransmissions, which reduces the chance of contention and collisions. In current dynamic probabilistic algorithm, the retransmission probability (pt) is formulated as a linear/non-linear function of a single variable, the number of first-hop neighbors (k). However, such algorithm is suffers in the presence of noise due to increasing packet-loss. In this paper, the authors propose a new dynamic probabilistic algorithm in which pt is determined locally by the retransmitting nodes considering both k and the noise-level. This algorithm is referred to as the dynamic noise-dependent probabilistic (DNDP) algorithm. The performance of the DNDP algorithm is evaluated through simulations using the MANET simulator (MANSim). The simulation results show that the DNDP algorithm presents higher network reachability than the dynamic probabilistic algorithm at a reasonable increase in the number of retransmissions for a wide range of noise-level. The effects of nodes densities and nodes speeds on the performance of the DNDP algorithm are also investigated.
Lessons Learned about Designing Augmented Realities
Authors: O’Shea Patrick , Mitchell Rebecca , Johnston Catherine , Dede Chris
Published: February 2011

While utilizing GPS-enabled handheld computing units, we have developed and studied augmented reality (AR) curricula to help middle school students learn literacy and math. In AR, students move around an outdoor physical environment, interacting with virtual characters and artifacts on their handheld computer. These invisible objects and characters provide clues to help solve a mystery, guiding the students through a process of inquiry and evidence building. The first AR curriculum we developed, Alien Contact! is based on a scenario where aliens have crash landed near the students’ middle school. Students, working in teams, learn math and literacy skills in the course of determining why the aliens have come to earth. This study describes the design heuristics used during the initial development and deployment of Alien Contact!, the results of two formative evaluations of this curriculum, and the impact these findings have had on revising our design heuristics for a subsequent AR curriculum about beached whales, called Gray Anatomy.
When People Get in the Way
Authors: Bagley Elizabeth , Shaffer David Williamson
Published: February 2011

A growing body of research suggests that computer games can help players learn to integrate knowledge and skills with values in complex domains of real world problem solving. In particular, research suggests that epistemic games—games where players think and act like real world professionals—can link knowledge, skills, and values into professional ways of thinking. Here, we look at how the epistemic game Urban Science develops civic thinking in young people as they learn about urban ecology by role-playing as urban planners redesigning a city. Specifically, we ask whether and how overcoming authentic obstacles from the profession of urban planning in the virtual world of a role-playing game can link civic values with the knowledge and skills young people need to solve complex social and ecological problems—and thus be a powerful context for learning civic thinking.
Player Types and Quality Perceptions
Authors: Weber René , Shaw Patrick
Published: February 2011

Little is known about how people select, play, and evaluate video games. Video game developers, for example, are forced to make multi-million dollar decisions based on hunches and guesses. Through social cognitive theory, one can understand video game playing as an overt behavior determined by expected outcomes as a result of direct and observational learning processes. Players have different theoretically derived needs for playing video games and use symbolic representations of their experiences with video games (quality perceptions) to determine whether playing a specific video game will satisfy those needs. A series of in-depth interviews and a subsequent survey with students of a large mid-western university was conducted to enumerate groups of similar players (player types), and video game quality perceptions. Both concepts were used to provide empirical evidence for a model to predict video game playing. Results show that the best prediction models are those that include player type specific quality perceptions.
Creating Virtual Alter Egos or Superheroines? Gamers' Strategies of Avatar Creation in Terms of Gender and Sex
Authors: Trepte Sabine , Reinecke Leonard , Behr Katharina-Maria
Published: February 2011

Who do people want to be in virtual worlds? Video game players can create their avatars with characteristics similar to themselves, create a superhero that is predominantly designed to win, or chose an in-between strategy. In a quasi-experimental study, players’ strategies of avatar choice were investigated. Participants created an avatar they would like to play with for five game descriptions and two gaming scenarios by choosing from a list of (pre-tested) masculine and feminine avatar features. Additionally, participants chose their avatars’ biological sex. The results reveal a mixed strategy: On the one hand, the avatar’s features were chosen in accordance with the game’s demands to facilitate mastery of the game. On the other hand, players strived for identification with their avatar and thus preferred avatars of their own sex. Participants rated those game descriptions and gaming scenarios more entertaining which required avatar features in line with their own sex role.
Video Game Representations as Cues for Collaboration and Learning
Authors: Sharritt Matthew J. , Suthers Daniel D.
Published: February 2011

Literature suggests that games can support learning in schools by enabling creative problem solving, allowing dynamic resource allocation, by providing a motivating, immersive activity, and by supporting explorations of identity. A descriptive, inductive study was carried out to identify how high school students in a school setting make use of the video game interface and its representations. Results demonstrate that specific cues direct attention, helping to focus efforts on new or underutilized game tasks. In addition, consistent and well-organized visualizations encourage learning and collaboration among students by providing shared referential resources and scaffolding coordinated sequences of problem solving acts during gameplay. Conversely, when affordances are inconsistently represented, students’ focus can shift from problem solving at the goal level (game strategy, etc.) to problem solving why the game interface is frustrating their goals. In general, the design of game representations and behaviors can help guide or hinder student learning.
Game Design and the Challenge-Avoiding, Self-Validator Player Type
Authors: Heeter Carrie , Magerko Brian , Medler Ben , Fitzgerald Joe
Published: February 2011

Achiever and Explorer player types are well known in MMOs and educational games. Players who enjoy being a winner, but dislike hard challenges (“Self-Validators”) are a heretofore ignored but commonly occurring player type. Self-Validators worry about and are distressed by failing. They can simply avoid playing overly difficult games for entertainment. But in a required learning game, Self-Validators’ excessive worry about failing can interfere with learning. The authors consider whether and how eight very different modern games accommodate Explorers, Achievers, and Self-Validators and discuss implications for entertainment and learning game design and research. Seven of eight diverse games analyzed primarily served either the Explorer or Achiever player type. Self-Validators were partially accommodated in some Achiever-oriented games, through user-selectable difficulty. Design with all three types in mind would encourage inclusion of features that enable players to optimize their preferred style of play.
Using Recommendation Systems to Adapt Gameplay
Authors: Medler Ben
Published: February 2011

Recommendation systems are key components in many Web applications (Amazon, Netflix, eHarmony). Each system gathers user input, such as the products they buy, and searches for patterns in order to determine user preferences and tastes. These preferences are then used to recommend other content that a user may enjoy. Games on the other hand are often designed with a one-size-fits-all approach not taking player preferences into account. However there is a growing interest in both the games industry and game research communities to begin incorporating systems that can adapt, or alter how the game functions, to specific players. This article examines how Web application recommendation systems compare to current games that adapt their gameplay to specific players. The comparison shows that current games do not use recommendation methods that are data intensive or collaborative when adapting to players. Design suggestions are offered within this manuscript for how game developers can benefit from incorporating the lesser used recommendation methods.
Bio-Affective Computer Interface for Game Interaction
Authors: Arroyo-Palacios Jorge , Romano Daniela M.
Published: February 2011

Affective bio-feedback can be an important instrument to enhance the game experience. Several studies have provided evidence of the usefulness of physiological signals for affective gaming; however, due to the limited knowledge about the distinctive autonomic signatures for every emotion, the pattern matching models employed are limited in the number of emotions they are able to classify. This paper presents a bio-affective gaming interface (BAGI) that can be used to customize a game experience according to the player’s emotional response. Its architecture offers important characteristics for gaming that are important because they make possible the reusability of previous findings and the inclusion of new models to the system. In order to prove the effectiveness of BAGI, two different types of neural networks have been trained to recognize emotions. They were incorporated into the system to customize, in real-time, the computer wallpaper according to the emotion experienced by the user. Best results were obtained with a probabilistic neural network with accuracy results of 84.46% on the training data and 78.38% on the validation for new independent data sets.
Automated Event Recognition for Football Commentary Generation
Authors: Zheng Maliang , Kudenko Daniel
Published: February 2011

The enjoyment of many games can be enhanced by in-game commentaries. In this paper, the authors focus on the automatic generation of commentaries for football games, using Championship Manager as a case study. The basis of this approach is a real-time mapping of game states to commentary concepts, such as “dangerous situation for team A”. While in some cases it is feasible to provide such a mapping by hand-coding, in some cases it is not straight-forward because the meaning of the concepts cannot be easily formalized. In these cases, the authors propose to use inductive learning techniques that learn such a mapping from annotated game traces.
Development of Tumor-Infiltrating CD8+ T Cell Memory Precursor Effector Cells and Antimelanoma Memory Responses Are the Result of Vaccination and TGF-β Blockade during the Perioperative Period of Tumor Resection
Authors: Bellavance Emily C. , Kohlhapp Frederick J. , Zloza Andrew , O’Sullivan Jeremy A. , McCracken James , Jagoda Michael C. , Lacek Andrew T. , Posner Mitchell C. , Guevara-Patino Jose A.
Published: February 2011

A main goal of cancer immunology research is the formation of Ag-specific memory T cell immunity capable of activation upon tumor re-encounter. The requirements necessary to overcome the inhibitory signals present in the tumor microenvironment and form such memory T cell responses are unknown. In contrast to previous studies targeting tumors expressing highly immunogenic model Ags, we demonstrate that alleviating tumor-induced suppression along with vaccination against authentic Ags during the perioperative period provides long-lasting protection against a highly suppressive and poorly immunogenic melanoma. In this study, we employed DNA vaccination with an immunologically optimized mouse melanoma-shared Ag, Trp1ee/ng, combined with systemic TGF-β blockade during the perioperative period of primary tumor resection, to confer protection against B16 melanoma, and against JBRH, an independently derived melanoma unrelated to B16. Importantly, we demonstrate that correlative to memory responses, perioperative immunotherapy increases the formation of tumor-infiltrating and tumor-reactive CD8+ T cells expressing low levels of the transcription factor T-bet, defined as memory precursor effector cells. We show that conditions for an immunologically fertile environment are met when TGF-β blockade and vaccination are applied during the perioperative period of primary tumor resection. These findings address limitations of current CD8+ T cell immunotherapies against cancer by generating effective CD8+ T cell memory recall responses.
OX40 Complexes with Phosphoinositide 3-Kinase and Protein Kinase B (PKB) To Augment TCR-Dependent PKB Signaling
Authors: So Takanori , Choi Heonsik , Croft Michael
Published: February 2011

T lymphocyte activation requires signal 1 from the TCR and signal 2 from costimulatory receptors. For long-lasting immunity, growth and survival signals imparted through the Akt/protein kinase B (PKB) pathway in activated or effector T cells are important, and these can be strongly influenced by signaling from OX40 (CD134), a member of the TNFR superfamily. In the absence of OX40, T cells do not expand efficiently to Ag, and memory formation is impaired. How most costimulatory receptors integrate their signals with those from Ag through the TCR is not clear, including whether OX40 directly recruits PKB or molecules that regulate PKB. We show that OX40 after ligation by OX40L assembled a signaling complex that contained the adapter TNFR-associated factor 2 as well as PKB and its upstream activator phosphoinositide 3-kinase (PI3K). Recruitment of PKB and PI3K were dependent on TNFR-associated factor 2 and on translocation of OX40 into detergent-insoluble membrane lipid microdomains but independent of TCR engagement. However, OX40 only resulted in strong phosphorylation and functional activation of the PI3K–PKB pathway when Ag was recognized. Therefore, OX40 primarily functions to augment PKB signaling in T cells by enhancing the amount of PI3K and PKB available to the TCR. This highlights a quantitative role of this TNFR family second signal to supplement signal 1.
Evaluating the Association between Insulin-Like Growth Factor-1 Values and Short-Term Survival Rates following Acute Myocardial Infarction
Authors: Hajsadeghi Shokoufeh , Mohseni Hamed , Moradi Masoud , Rahmani Elham , Kordshakeri Kiarash , Manteghi Mohammad Javad , Tokazebani Masoud , Mollahoseini Reza
Published: February 2011

Backgrounds

In recent years, low levels of Insulin-like Growth Factor-1 (IGF-1) have been suggested to be associated with higher risks of developing heart failure and higher long-term mortality rates following Acute Myocardial Infarction (AMI). However, the effect of IGF-1 levels on short-term survival has been rarely studied. In this study we aimed to assess any possible association between serum IGF-1 concentration following AMI and short-term survival rates.

Methods

In this study, serum total IGF-1 levels were measured in 56 patients within 24 hours following AMI and were compared to 56 individuals with no cardiovascular disease. Patients were followed up to death or discharge from hospital (median = 6 days) and survival curves were compared based on median IGF-1 value.

Results

Mean (±SD) of serum IGF-1 levels were 232.73 ng/ml (±81.74) and 211.00 ng/ml (±58.22) in survived and expired patients respectively and the difference was not statistically significant ( P value = 0.501). The difference between survival curves was also not statistically significant ( P value = 0.246).

Conclusion

According to findings of this study, serum total IGF-1 concentration does not seem to be associated with short-term survival rates.