528361
Eliminating Bottlenecks in Overlay Multicast
Recently many overlay multicast systems have been proposed due to the limited availability of IP multicast. Because they perform multicast forwarding without support from routers, data may be delivered multiple times over the same physical link, causing a bottleneck. This problem is more serious for applications demanding high bandwidth such as multimedia distribution. Although such bottlenecks can be removed by changing overlay topology, a naive approach may create bottlenecks in other parts of the network. In this paper, We propose an algorithm that removes all bottlenecks caused by the redundant data delivery of overlay multicast, detecting such bottlenecks using a wavelet-based technique we recently proposed. In a case where the source rate is constant and the available bandwidth of each link is not less than the source rate, our algorithm guarantees that every node receives at the full source rate. Simulation results show that even in a network with a dense receiver population, our algorithm finds a tree that satisfies all the receiving nodes while other heuristic-based approaches often fail.
241209
Transient behaviors of TCP-friendly congestion control protocols
We investigate the fairness, smoothness, responsiveness, and aggressiveness of TCP and three representative TCP-friendly congestion control protocols: GAIMD, TFRC, and TEAR. The properties are evaluated both analytically and via simulation by studying protocol responses to three network environment changes. The first environment change is the inherent fluctuations in a stationary network environment. Under this scenario, we consider three types of sending rate variations: smoothness, short-term fairness, and long-term fairness. For a stationary environment, we observe that smoothness and fairness are positively correlated. We derive an analytical expression for the sending rate coefficient of variation for each of the four protocols. These analytical results match well with experimental results. The other two environment changes we study are a step increase of network congestion and a step increase of available bandwidth. Protocol responses to these changes reflect their responsiveness and aggressiveness, respectively.
12348020
Using a clone genealogy extractor for understanding and supporting evolution of code clones
Programmers often create similar code snippets or reuse existing code snippets by copying and pasting. Code clones---syntactically and semantically similar code snippets---can cause problems during software maintenance because programmers may need to locate code clones and change them consistently. In this work, we investigate (1) how code clones evolve, (2) how many code clones impose maintenance challenges, and (3) what kind of tool or engineering process would be useful for maintaining code clones.Based on a formal definition of clone evolution, we built a clone genealogy tool that automatically extracts the history of code clones from a source code repository (CVS). Our clone genealogy tool enables several analyses that reveal evolutionary characteristics of code clones. Our initial results suggest that aggressive refactoring may not be the best solution for all code clones; thus, we propose alternative tool solutions that assist in maintaining code clones using clone genealogy information.
26955217
On Temporal Aggregate Processing Based on Time Points
Temporal aggregation is an extension of conventional aggregate on the domain and range of aggregates to include the time concept. In this paper, we propose a new tree-based temporal aggregation processing method. The time complexity of the proposed method is better than those of the existing methods. The experimental results indicate that our proposed method ourperforms the existing methods.
63258
A doubly distributed genetic algorithm for network coding
We present a genetic algorithm which is distributed in two novel ways: along genotype and temporal axes. Our algorithm first distributes, for every member of the population, a subset of the genotype to each network node, rather thana subset of the population to each. This genotype distribution is shown to offer a significant gain in running time. Then, for efficient use of the computational resources in the network, our algorithm divides the candidate solutions intopipelined sets and thus the distribution is in the temporal domain, rather that in the spatial domain. This temporal distribution may lead to temporal inconsistency in selection and replacement, however our experiments yield better efficiency in terms of the time to convergence without incurring significant penalties.
45814871
A Multimedia Information System for Home Health-Care Support
The author describes Guardian, a knowledge based home health-care support system in the domain of childhood leukaemia. Guardian is part of a joint project between IBM Research and the New England Medical Center for building a prototype home-care system for children with leukaemia. The prototype system consists of a set of applications, including consultation and symptoms analysis, procedure guidance, emotional support, and communications, implemented in Smalltalk/OS2. This article focuses on the knowledge-based system, which helps parents better understand the symptoms or problems their child is experiencing and provides them with relevant therapeutic information.
3207967
ArrayXPath: mapping and visualizing microarray gene-expression data with integrated biological pathway resources using Scalable Vector Graphics
Biological pathways can provide key information on the organization of biological systems. ArrayXPath (http://www.snubi.org/software/ArrayXPath/) is a web-based service for mapping and visualizing microarray gene-expression data for integrated biological pathway resources using Scalable Vector Graphics (SVG). By integrating major bio-databases and searching pathway resources, ArrayXPath automatically maps different types of identifiers from microarray probes and pathway elements. When one inputs gene-expression clusters, ArrayXPath produces a list of the best matching pathways for each cluster. We applied Fisher's exact test and the false discovery rate (FDR) to evaluate the statistical significance of the association between a cluster and a pathway while correcting the multiple-comparison problem. ArrayXPath produces Javascript-enabled SVGs for web-enabled interactive visualization of pathways integrated with gene-expression profiles.