Individual Messages Research Articles

Efficient fair algorithms for message communication

A computer network serves distributed applications by communicating messages between their remote ends. Many such applications desire minimal delay for their messages. Beside this efficiency objective, allocation of the network capacity is also subject to the fairness constraint of not shutting off communication for any individual message. Processor Sharing (PS) is a de facto standard of fairness but provides significantly higher average delay than Shortest Remaining Processing Time (SRPT), which is an optimally efficient but unfair algorithm. In this paper, we explore efficient fair algorithms for message communication where fairness means that no message is delivered later than under PS. First, we introduce a slack system to characterize fair algorithms completely and develop efficient fair algorithms called Pessimistic Fair Sojourn Protocol (PFSP), Optimistic Fair Sojourn Protocol (OFSP), and Shortest Fair Sojourn (SFS). Then, we prove that a fair online algorithm does not assure minimal average delay attainable with fairness. Our analysis also reveals lower bounds on worst-case inefficiency of fair algorithms. We conduct extensive simulations for various distributions of message sizes and arrival times. During either temporary overload or steady-state operation, SFS and other newly proposed fair algorithms support SRPT-like efficiency and consistently provide much smaller average delay than PS.

Effects of channel bandwidth variation on performance of individual messages in spatially and temporally heterogeneous communication networks

As the domain of communication systems grows, heterogeneity among computers and subnetworks employed for a task also increases. Channel bandwidth available for a message on a communication network ...

Building a robust distributed system: some lessons from R-GMA

R-GMA, as deployed by LCG, is a large distributed system. We are currently addressing some design issues to make it highly reliable, and fault tolerant. In validating the new design, there were two classes of problems to consider: one related to the flow of data and the other to the loss of control messages. R-GMA streams data from one place to another; there is a need to consider the behaviour when data is being inserted more rapidly into the system than taken out and more generally how to deal with bottlenecks. In the original R-GMA design the system tried hard to deliver all control messages; those messages that were not delivered quickly were queued for retry later. Badly configured firewalls, network problems or very slow machines could all lead to long queues of messages; many of the messages on the queue should have been replaced by later ones. In the new design no individual control message is critical; the system just needs to know if each message was received successfully. The system should also avoid single points of failure. However this can require complex code resulting in a system that is actually less reliable. We describe how we have dealt with bottlenecks in the flow of data, loss of control messages and the elimination of single points of failure to produce a robust R-GMA design. The work presented, though in the context of R-GMA, is applicable to any large distributed system.

Low Latency Wireless Ad Hoc Networking: Power and Bandwidth Challenges and a Solution

This paper is concerned with the scaling of the number of relay nodes (i.e., hops) individual messages have to transit through in a large-scale wireless ad hoc network (WANET); we call this hop-count as network latency (NL). A large network latency affects all aspects of data communication in a WANET, including an increase in delay, packet loss, and the power needed to process and store messages in nodes lying on the relay path. We consider network management and data routing challenges in WANETs with scalable network latency, e.g., when NL increases only polylogarithmically in the network size. On the physical side, reducing network latency imposes a significantly higher power and bandwidth demand on nodes, and are captured in a set of new bounds derived in this paper. On the protocol front, designing distributed routing protocols that can guarantee the delivery of data packets within a scalable number of hops is a challenging task. To solve this, we introduce multi-resolution randomized hierarchy (MRRH), a novel power and bandwidth efficient WANET protocol with scalable network latency. MRRH uses a randomized algorithm for building and maintaining a random hierarchical network topology, which together with the proposed routing algorithm, can guarantee efficient delivery of data packets in the wireless network. For a network of size N, MRRH can provide an average latency of only O(log <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> N). The power consumption and bandwidth requirements of MRRH are shown to be nearly optimal for the latency it provides. Therefore, MRRH is a provably efficient candidate for truly large-scale wireless ad hoc networking.

The impact of television dependency on teleshopping adoption

PurposeTo analyse key drivers of television dependency and its impact on teleshopping adoption.Design/methodology/approachThe applicability of the media dependency scale is tested in the Spanish market. The impact of demographics, television exposure and television affinity on television dependency is analysed together with behavioural changes deriving from television dependency (willingness to teleshopping).FindingsData analysis shows that the media dependency scale needs to be adapted to the Spanish market and Spanish televiewers show intermediate levels of television dependency. Dependent televiewers are mainly mature, feel high‐television affinity and have high levels of exposure as televiewers. Television dependency determines teleshopping adoption, with the most relevant factor being that of searching guides for decision taking and fun.Practical implicationsThis research enables companies to know the different objectives which television can help consumers to attain and, therefore, what aspects to highlight in their direct marketing strategies. Television agents should exploit the dimensions television offers to increase individual dependency and message effectiveness. The significant influence that “decision taking and fun” exerts on willingness to teleshopping shows managers that program contents become a key tool to increase future television purchases.Originality/valueDespite dramatic online differences were discovered between television dependent and non‐dependent consumers, very limited research has been conducted to examine them. There are still no enough studies that analyse the background and effects of television dependency on the non‐purchasing televiewers behaviour. This paper analyses the background of television dependency and its influence on future purchase intentions of non‐buyer Spanish televiewers.

Single-document and multi-document summarization techniques for email threads using sentence compression

We present two approaches to email thread summarization: collective message summarization (CMS) applies a multi-document summarization approach, while individual message summarization (IMS) treats the problem as a sequence of single-document summarization tasks. Both approaches are implemented in our general framework driven by sentence compression. Instead of a purely extractive approach, we employ linguistic and statistical methods to generate multiple compressions, and then select from those candidates to produce a final summary. We demonstrate these ideas on the Enron email collection – a very challenging corpus because of the highly technical language. Experimental results point to two findings: that CMS represents a better approach to email thread summarization, and that current sentence compression techniques do not improve summarization performance in this genre.

Youth Audience Segmentation Strategies for Smoking-Prevention Mass Media Campaigns Based on Message Appeal

Mass media interventions are among the strategies recommended for youth cigarette smoking prevention, but little is known about optimal methods for reaching diverse youth audiences. Grades 4 through 12 samples of youth from four states (n = 1,230) rated smoking-prevention messages in classroom settings. Similar proportions of African American, Hispanic, and White youth participated. Impact of audience characteristics on message appeal ratings was assessed to provide guidance for audience segmentation strategies. Age had a strong effect on individual message appeal. The effect of gender also was significant. Message ratings were similar among the younger racial/ethnic groups, but differences were found for older African American youth. Lower academic achievement was associated with lower appeal scores for some messages. Age should be a primary consideration in developing and delivering smoking-prevention messages to youth audiences. The unique needs of boys and girls and older African American adolescents should also be considered.

Individualised health marketing using SMS — A smoking cessation case

This paper describes a case study of an advertising campaign that has individual short message service (SMS) interaction concerning a health marketing message as the central element. Decisive factors include the widespread use of SMS, the opportunity for interaction and the independence from time and place. The objective of this study was to evaluate the feasibility of engaging health consumers through SMS campaigns. Advertisements were run for four weeks from 1st January, 2006 to 1st February, 2006 with the message ‘Test yourself to see what kind of a smoker you are and get help to stop smoking’. The test is a modified Fagerstrom questionnaire. Over a four-week period, 10,565 people participated in the test. The case illustrates that it is most certainly possible to engage consumers and provide individual marketing via SMS mobile telephony.

Processing Internet-derived Text--Creating a Corpus of Usenet Messages

In recent years, linguists have become increasingly interested in the language of the Internet—both as an object of investigation as well as a source of authentic data to complement traditional electronic corpora. However, Internet-derived data is typically very messy data and a conversion process is often required in order to enable researchers to carry out a reliable quantitative investigation of the patterns observed with the help of standard corpus tools. In this article, I discuss the technical and methodological aspects involved in creating a large corpus of asynchronous computer-mediated communication by downloading and post-processing hundreds of thousands messages posted in twelve Usenet newsgroups. After describing how messages can be arranged into hierarchically structured discussion threads, I focus at some length on the strategies that are required to correctly assign authorship to the different textual elements in individual messages. My algorithms have a success rate of well over 90% for most newsgroups and the resulting corpus can thus serve as a suitable basis for an investigation into the interactive strategies employed in this particular type of written communication.

Type checking a multithreaded functional language with session types

We define a language whose type system, incorporating session types, allows complex protocols to be specified by types and verified by static type checking. A session type, associated with a communication channel, specifies the state transitions of a protocol and also the data types of messages associated with transitions; thus type checking can verify both correctness of individual messages and correctness of sequences of transitions. Previously, session types have mainly been studied in the context of the π -calculus; instead, our formulation is based on a multithreaded functional language with side-effecting input/output operations. Our typing judgements statically describe dynamic changes in the types of channels, and our function types not only specify argument and result types but also describe changes in channels. We formalize the syntax, semantics and type checking system of our language, and prove subject reduction and runtime type safety theorems.

Explaining Internet dependency

PurposeTo analyse key drivers of Internet dependency and its impact on willingness to purchase online.Design/methodology/approachThe applicability of the media dependency scale is tested in the Spanish market. The impact of demographics, Internet exposure, online experience and Internet affinity on Internet dependency is analysed together with behavioural changes deriving from Internet dependency (willingness to purchase online).FindingsData analysis shows that the media dependency scale needs to be adapted to the Spanish market and Spanish Internet users show intermediate levels of Internet dependency. Dependent users are mainly young, highly‐educated, feel Internet affinity and have high levels of exposure and experience as Internet users. Internet dependency determines willingness to purchase online, with the most relevant factor being that of searching for information to take decisions.Practical implicationsThis research enables companies to know the different objectives which Internet can help consumers to attain and, therefore, what aspects to highlight in their communication strategies. Internet agents should exploit the dimensions Internet offers to increase individual dependency and message effectiveness. The significant influence that searching for information exerts on willingness to purchase online shows managers that web contents become a key tool to increase future online purchases.Originality/valueDespite dramatic online differences were discovered between Internet dependent and non‐dependent users, very limited research has been conducted to examine them. There are still not enough studies that analyse the effects of Internet dependency on the non‐purchasing Internet users behaviour. This paper analyses the background of Internet dependency and its influence on future purchase intentions of non‐buyer Internet users.

Affect and an Effective Online Therapeutic Community

Affect and an Effective Online Therapeutic Community

Email Surveillance Using Non-negative Matrix Factorization

In this study, we apply a non-negative matrix factorization approach for the extraction and detection of concepts or topics from electronic mail messages. For the publicly released Enron electronic mail collection, we encode sparse term-by-message matrices and use a low rank non-negative matrix factorization algorithm to preserve natural data non-negativity and avoid subtractive basis vector and encoding interactions present in techniques such as principal component analysis. Results in topic detection and message clustering are discussed in the context of published Enron business practices and activities, and benchmarks addressing the computational complexity of our approach are provided. The resulting basis vectors and matrix projections of this approach can be used to identify and monitor underlying semantic features (topics) and message clusters in a general or high-level way without the need to read individual electronic mail messages.

Politics As Usual, or Politics Unusual? Position Taking and Dialogue on Campaign Websites in the 2002 U.S. Elections

Many consider the World Wide Web to be nothing more than an additional medium alongside others in which established patterns of political behavior and information flows are played out anew; others contend that the special characteristics of the Web hold the potential to produce fundamentally different patterns of political behavior than those found offline. This article analyzes the occurrence of position taking and issue dialogue on campaign websites associated with a random sample of 200 races from the U.S. 2002 election cycle. Though this study found some similarities between online and offline campaigning, it also identified ways in which the individual messages and overall political information environment created by candidates and available to voters through the Web in 2002 did not conform to the usual patterns found in the offline world of print and broadcast communication.

Politics As Usual, or Politics Unusual? Position Taking and Dialogue on Campaign Websites in the 2002 U.S. Elections

Many consider the World Wide Web to be nothing more than an additional medium alongside others in which established patterns of political behavior and information flows are played out anew; others contend that the special characteristics of the Web hold the potential to produce fundamentally different patterns of political behavior than those found offline. This article analyzes the occurrence of position taking and issue dialogue on campaign websites associated with a random sample of 200 races from the U.S. 2002 election cycle. Though this study found some similarities between online and offline campaigning, it also identified ways in which the individual messages and overall political information environment created by candidates and available to voters through the Web in 2002 did not conform to the usual patterns found in the offline world of print and broadcast communication.

Protocol engineering for web services conversations

Although web services aim to bring about seamless and effective communication in a wide variety of Internet applications, the interactions between them are currently limited to simple request–response exchanges. However, in the longer term we believe this is unsustainable. In particular, we believe that more complex protocols for web service conversations are necessary if the participants are to tailor their needs and offers to the prevailing context and they are to coordinate multiple services in open and realistic environments. To this end, this paper combines and extends two recent web service languages, WS-Conversation Language ( WSCL) and WS-Agreement, in order to obtain a method for engineering protocols of sufficient expressiveness for the next generation of flexible and autonomous services. Specifically, we propose that the protocols include speech-acts as the individual messages and we show how to model such speech-acts as WS-Agreement schemas, which can, in turn, be imported into the specification of the protocols in WSCL. To demonstrate our approach, we express a standard contracting protocol in the extended WSCL/WS-Agreement languages. Furthermore, we use statechart notation as a visual counterpart to help developers write clients that flexibly interact with a service and to help users to better understand how to interact with a service. Finally, we show that the translation between statecharts and WSCL/WS-Agreement protocols is straightforward.

Chaotic wavelength division multiplexing for optical communication

We demonstrate wavelength division multiplexing with chaotic subcarriers in two pairs of one-way-coupled Nd:YVO4 microchip lasers. Two individual digital messages are encoded on two chaotic carriers with different wavelengths in two transmitters by the chaotic masking method, and the mixed signals are sent to two receivers. Dual synchronization of chaos is used to obtain the original chaotic waveforms in the receivers. Two messages are decoded by filtering the difference of the laser outputs between the transmitter and the receiver by use of a low-pass filter for each pair of lasers. The message recovery can be achieved more easily when messages with small amplitude and low frequency are used.

COMMUNICATION SCHEDULING WITH RE-ROUTING BASED ON STATIC AND HYBRID TECHNIQUES

In massively parallel systems, the performance gains are often significantly diminished by the inherent communication overhead. This overhead is caused by the required message passing resulting from the task allocation scheme. In this paper, techniques to reduce this communication overhead by both scheduling the communication and determining the routing that the messages should take within a tightly-coupled processor network are presented. Using the recently developed Collision Graph model, static scheduling algorithms are derived which work at compile-time to determine the ordering and routing of the individual message transmissions. Since a priori knowledge about the network traffic required by static scheduling may not be available or accurate, this work also considers dynamic scheduling. A novel hybrid technique is presented which operates in a dynamic environment yet uses known information obtained by analyzing the communication patterns. Experiments performed show significant improvement over baseline techniques.

New Approaches to Overcoming E-Mail Overload

As e-mail has become the preferred medium for communication, the inbox and mail folders become one hub for organizing activities and schedule. The combination of a natural rise in message volume and the large amounts of unsolicited bulk messages (spam) have led some to suggest that the usefulness of e-mail is at an end; users feel overwhelmed by the sheer numbers of individual messages and the effort to manage the inbox. This paper frames the issue of e-mail/message overload as a specific example of data overload and uses previous results to suggest three design concepts – cognitive buoyancy, e-mail constellations, and the intelligent subject line – for use in e-mail.

Postgraduate Diploma/Master of Science in Wound Healing and Tissue Repair

Keywords: Education; Wound care; Master's course; Postgraduate study; Continuing education; Web-based education