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Quantification of biofilm structures by the novel computer program COMSTAT
, 2000
"... tum growing into microcolonies, which were eventually succeeded by long filaments and elongated cell clusters. P. aeruginosa colonized the entire substratum, and formed flat, uniform biofilms. P. aureofaciens resembled P. aeruginosa, but had a stronger tendency to form microcolonies. Finally, ..."
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Cited by 135 (19 self)
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tum growing into microcolonies, which were eventually succeeded by long filaments and elongated cell clusters. P. aeruginosa colonized the entire substratum, and formed flat, uniform biofilms. P. aureofaciens resembled P. aeruginosa, but had a stronger tendency to form microcolonies. Finally, the biofilm structures of P. fluorescens had a phenotype intermediate between those of P. putida and P. aureofaciens. Analysis of biofilms of P. aureofaciens growing on 0<03 mM, 0<1mMor0<5mM citrate minimal media showed that mean biofilm thickness increased with increasing citrate concentration. Moreover, biofilm roughness increased with lower citrate concentrations, whereas surface to volume ratio increased with higher citrate concentrations. Keywords : Pseudomonas, biofilm structure, image analysis, qu
Charging from Sampled Network Usage
, 2001
"... IP flows have heavytailed packet and byte size distributions. This make them poor candidates for uniform samplingi.e. selecting 1 in N flowssince omission or inclusion of a large flow can have a large effect on estimated total traffic. Flows selected in this manner are thus unsuitable for use ..."
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Cited by 112 (13 self)
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IP flows have heavytailed packet and byte size distributions. This make them poor candidates for uniform samplingi.e. selecting 1 in N flowssince omission or inclusion of a large flow can have a large effect on estimated total traffic. Flows selected in this manner are thus unsuitable for use in usage sensitive billing. We propose instead using a sizedependent sampling scheme which gives priority to the larger contributions to customer usage. This turns the heavy tails to our advantage; we can obtain accurate estimates of customer usage from a relatively small number of important samples. The sampling scheme allows us to control error when charging is sensitive to estimated usage only above a given base level. A refinement allows us to strictly limit the chance that a customers estimated usage will exceed their actual usage. Furthermore, we show that a secondary goal, that of controlling the rate at which samples are produced, can be fulfilled provided the billing cycle is sufficiently long. All these claims are supported by experiments on flow traces gathered from a commercial network.
A genetic algorithm for the weight setting problem in OSPF routing
 Journal of Combinatorial Optimization
, 2002
"... Abstract. With the growth of the Internet, Internet Service Providers (ISPs) try to meet the increasing traffic demand with new technology and improved utilization of existing resources. Routing of data packets can affect network utilization. Packets are sent along network paths from source to desti ..."
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Cited by 108 (27 self)
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Abstract. With the growth of the Internet, Internet Service Providers (ISPs) try to meet the increasing traffic demand with new technology and improved utilization of existing resources. Routing of data packets can affect network utilization. Packets are sent along network paths from source to destination following a protocol. Open Shortest Path First (OSPF) is the most commonly used intradomain Internet routing protocol (IRP). Traffic flow is routed along shortest paths, splitting flow at nodes with several outgoing links on a shortest path to the destination IP address. Link weights are assigned by the network operator. A path length is the sum of the weights of the links in the path. The OSPF weight setting (OSPFWS) problem seeks a set of weights that optimizes network performance. We study the problem of optimizing OSPF weights, given a set of projected demands, with the objective of minimizing network congestion. The weight assignment problem is NPhard. We present a genetic algorithm (GA) to solve the OSPFWS problem. We compare our results with the best known and commonly used heuristics for OSPF weight setting, as well as with a lower bound of the optimal multicommodity flow routing, which is a linear programming relaxation of the OSPFWS problem. Computational experiments are made on the AT&T Worldnet backbone with projected demands, and on twelve instances of synthetic networks. 1.
Increasing internet capacity using local search
 Computational Optimization and Applications
, 2004
"... but often the main goal is to avoid congestion, i.e. overloading of links, and the standard heuristic recommended by Cisco (a major router vendor) is to make the weight of a link inversely proportional to its capacity. We study the problem of optimizing OSPF weights for a given a set of projected de ..."
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Cited by 95 (8 self)
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but often the main goal is to avoid congestion, i.e. overloading of links, and the standard heuristic recommended by Cisco (a major router vendor) is to make the weight of a link inversely proportional to its capacity. We study the problem of optimizing OSPF weights for a given a set of projected demands so as to avoid congestion. We show this problem is NPhard and propose a local search heuristic to solve it. We also provide worstcase results about the performance of OSPF routing vs. an optimal multicommodity flow routing. Our numerical experiments compare the results obtained with our local search heuristic to the optimal multicommodity flow routing, as well as simple and commonly used heuristics for setting the weights. Experiments were done with a proposed nextgeneration AT&T WorldNet backbone as well as synthetic internetworks.
Global Optimization Algorithms  Theory and Application
, 2011
"... This ebook is devoted to Global Optimization algorithms, which are methods for finding solutions of high quality for an incredible wide range of problems. We introduce the basic concepts of optimization and discuss features which make optimization problems difficult and thus, should be considered ..."
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Cited by 94 (26 self)
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This ebook is devoted to Global Optimization algorithms, which are methods for finding solutions of high quality for an incredible wide range of problems. We introduce the basic concepts of optimization and discuss features which make optimization problems difficult and thus, should be considered when trying to solve them. In this book, we focus on
On the Approximability of Numerical Taxonomy (Fitting Distances by Tree Metrics)
, 1995
"... We consider the problem of fitting an n \Theta n distance matrix D by a tree metric T . Let " be the distance to the closest tree metric, that is, " = min T fk T; D k1 g. First we present an O(n 2 ) algorithm for finding an additive tree T such that k T; D k1 3", giving the first a ..."
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Cited by 91 (4 self)
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We consider the problem of fitting an n \Theta n distance matrix D by a tree metric T . Let " be the distance to the closest tree metric, that is, " = min T fk T; D k1 g. First we present an O(n 2 ) algorithm for finding an additive tree T such that k T; D k1 3", giving the first
Properties and Prediction of Flow Statistics from Sampled Packet Streams
 In Proc. ACM SIGCOMM Internet Measurement Workshop
, 2002
"... Many routers can generate and export statistics on flows of packets that traverse them. Increasingly, high end routers form flow statistics from only a sampled packet stream in order to manage resource consumption involved. ..."
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Cited by 94 (4 self)
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Many routers can generate and export statistics on flows of packets that traverse them. Increasingly, high end routers form flow statistics from only a sampled packet stream in order to manage resource consumption involved.
A Region Inference Algorithm
 ACM TRANSACTIONS ON PROGRAMMING LANGUAGES AND SYSTEMS
, 1998
"... This article presents an algorithm which implements the specification. We prove that the algorithm is sound with respect to the region inference rules and that it always terminates even though the region inference rules permit polymorphic recursion in regions. The algorithm is the result of several ..."
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Cited by 89 (4 self)
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This article presents an algorithm which implements the specification. We prove that the algorithm is sound with respect to the region inference rules and that it always terminates even though the region inference rules permit polymorphic recursion in regions. The algorithm is the result of several years of experiments with region inference algorithms in the ML Kit, a compiler from Standard ML to assembly language. We report on practical experience with the algorithm and give hints on how to implement it.
FAME  A Flexible Appearance Modelling Environment
, 2003
"... Combined modelling of pixel intensities and shape has proven to be a very robust and widely applicable approach to interpret images. As such the Active Appearance Model (AAM) framework has been applied to a wide variety of problems within medical image analysis. This paper summarises AAM application ..."
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Cited by 83 (7 self)
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Combined modelling of pixel intensities and shape has proven to be a very robust and widely applicable approach to interpret images. As such the Active Appearance Model (AAM) framework has been applied to a wide variety of problems within medical image analysis. This paper summarises AAM applications within medicine and describes a public domain implementation, namely the Flexible Appearance Modelling Environment (FAME). We give guidelines for the use of this research platform, and show that the optimisation techniques used renders it applicable to interactive medical applications. To increase performance and make models generalise better, we apply parallel analysis to obtain automatic and objective model truncation. Further, two different AAM training methods are compared along with a reference case study carried out on crosssectional shortaxis cardiac magnetic resonance images and face images. Source code and annotated data sets needed to reproduce the results are put in the public domain for further investigation.
Compact NameIndependent Routing with Minimum Stretch
 In Proceedings of the 16th ACM Symposium on Parallelism in Algorithms and Architectures (SPAA 2004
, 2004
"... Given a weighted undirected network with arbitrary node names, we present a compact routing scheme, using a O(√n) space routing table at each node, and routing along paths of stretch 3, that is, at most thrice as long as the shortest paths. This is optimal in a very strong sense. It is kno ..."
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Cited by 77 (11 self)
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Given a weighted undirected network with arbitrary node names, we present a compact routing scheme, using a O(√n) space routing table at each node, and routing along paths of stretch 3, that is, at most thrice as long as the shortest paths. This is optimal in a very strong sense
Results 11  20
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