1,720,971 research outputs found
Migratory TCP: highly available internet services using connection migration
No full textWe evaluate the feasibility of using Migratory TCP (M-TCP), a reliable connection-oriented transport layer protocol that supports connection migration, for building highly available Internet services. M-TCP can transparently migrate the server endpoint of a live connection and assists server applications in resuming service on migrated connections. M-TCP provides a generic solution for the problem of service continuity and availability in the face of connectivity failures.
We have implemented M-TCP and present results of an experimental evaluation which shows it can efficiently provide support for highly available services. We illustrate the use of M-TCP in two applications. The first is a synthetic generic media streaming server. We show that, when the performance of the current server degrades, M-TCP an sustain throughput lose to the average server behavior by migrating connections to better servers. The second application is a transactional database server in which we have integrated support for migrating client connections. Using our system, a database frontend an continue the execution of a series of transactions submitted by a remote client in a session started with another front-end. The system allows a session to survive adverse conditions by connection migration, while ensuring that ACID semantics are preserved and that the execution is deterministic across migration.Technical report DCS-TR-46
Cooperative computing for distributed embedded systems
No full textDynamically connected. Although these systems will penetrate every possible domain of our daily life, the expectation is that they will operate outside our normal cognizance, requiring far less attention from the human users than the desktop computers today. The networked embedded computing era will challenge our ways of thinking and computing far more than the PC revolution did in the past. The current software and network architectures and their associated programming models were not designed for these scenarios. Traditional parallel and distributed computing models are based on a distribution of tasks across a stable cluster of similar processing units. In networks of embedded systems however, nodes have properties such as location or functionality that make them only partially substitutable in a specific task. Tasks need to execute on specific nodes to achieve prescribed objectives, necessitating the location of target nodes in a manner that allows partial substitution. We propose a computing model and a system architecture for distributed embedded systems where nodes “cooperate” by providing their computing and communication resources to distributed tasks. The system architecture for cooperative computing is based on Smart Messages (SM), which can be viewed as intelligent carriers of data in a network. Smart Messages are collections of code and mobile data that migrate through the network, a single network hop at a time, executing at each step. Smart Messages are responsible for their own routing. To validate the model we have implemented two previously proposed applications, Directed Diffusion and SPIN, for data collection and data dissemination in sensor networks. We have developed a simulator that executes Cooperative Computing applications and allows us to evaluate the performances by measuring both execution and communication time.Technical report DCS-TR-46
Self-Routing in Networks of Embedded Systems using Smart Messages
No full textSmart Messages provide a simple, yet flexible model for programming distributed applications in massive networks of embedded systems. A Smart Message (SM) is a dynamic collection of code and data that migrates through the network, routes itself at each node in the path, and executes on nodes of interest. The nodes of interest are named by properties or content. A key challenge in this model is the ability to discover target nodes, and to route SMs to them. In this paper we describe the SM self-routing mechanism, which provides high flexibility, scalability, and resilience to adverse network conditions. Using this mechanism, applications can choose among multiple content-based routing schemes, or even define the best suited routing algorithm for their needs. We present proof-of-concept implementation, simulation results, and analysis for three classes of content-based routing algorithms. We also show preliminary results for an SM prototype implementation on Compaq iPAQs using Wavelan 802.11 and Bluetooth for communicationTechnical report DCS-TR-48
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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