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37 results on '"Vaton, S."'

7. Screening for chlamydia trachomatis infection in pregnant women in Martinique

Author

Chout, Roger T., Vaton, S., Duval-Violton, D., Leguyader-Despres, P., and Orfila, J.

Subjects
Martinique -- Health aspects, Chlamydia infections -- Diagnosis, Medical screening -- Evaluation, Health
Abstract

Routinely testing for chlamydia infections in pregnant women may be a cost-effective way to control the spread of this disease in high-risk areas. Chlamydia is a sexually transmitted bacterial disease affecting the cervix and urinary tract. Chlamydia infection rates of pregnant widely vary around the world, from 2% to 50%. Pregnant women with chlamydia can experience complications with present and future deliveries. Infants born to women with chlamydia may have middle ear infections, lung diseases, or may die. Researchers tested and interviewed 1411 pregnant women for chlamydia infection on the intermediately developed island of Martinique. Nearly 27% of these women tested positive for chlamydia. Risk factors associated with this disease were having first intercourse before age 18, age less than 25 years, previous abortions, cervical infections, and previous candida infections. Treating complicated chlamydia infections during pregnancy could cost as much as 5 times that of testing and routine treatment.

Published
1995

10. Efficient methods for traffic matrix modeling and on-line estimation in large-scale IP networks

Author

Casas, P., Vaton, S., Fillatre, L., Therry Chonavel, Universidad de la República [Montevideo] (UDELAR), Département informatique (INFO), Université européenne de Bretagne - European University of Brittany (UEB)-Télécom Bretagne-Institut Mines-Télécom [Paris] (IMT), Laboratoire Modélisation et Sûreté des Systèmes (LM2S), Institut Charles Delaunay (ICD), Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS), Lab-STICC_TB_CID_TOMS, Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), Université européenne de Bretagne - European University of Brittany (UEB)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Télécom Bretagne-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université européenne de Bretagne - European University of Brittany (UEB)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Télécom Bretagne-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Département Signal et Communications (SC), Universidad de la República [Montevideo] (UCUR), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Télécom Bretagne-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-Université européenne de Bretagne - European University of Brittany (UEB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Télécom Bretagne-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-Université européenne de Bretagne - European University of Brittany (UEB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), and Institut Mines-Télécom [Paris] (IMT)-Télécom Bretagne-Université européenne de Bretagne - European University of Brittany (UEB)

Subjects
[INFO.INFO-NI]Computer Science [cs]/Networking and Internet Architecture [cs.NI], [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing
Abstract

International audience; Despite a large body of literature and methods devoted to the traffic matrix estimation problem, the inference of traffic flows volume from aggregated data represents a key subject facing the evolution of next generation networks. This is a particular problem in large-scale carrier networks, for which efficient, accurate and stable methods for traffic matrix modeling and estimation are vital and challenging to conceive. In the short-term, estimation methods must be efficient and stable to allow crucial real-time tasks such as on-line traffic monitoring. In the long-term, methods must provide an accurate picture of the traffic matrix to tackle problems such as network planning, design, and dimensioning. In this paper we present and compare two efficient methods for on-line traffic matrix estimation. Based on an original parsimonious linear model for traffic flows in large-scale networks, we present a simple approach to compute an accurate traffic matrix from easily available link traffic measurements. We further extend the validation of this parsimonious model to three operational backbone networks. We analyze in depth a method to recursively estimate the traffic matrix, studying the drawbacks and omissions of the former algorithm and proposing new extensions to solve these problems. We finally perform a comparative analysis of the performance of both methods in two operational backbone networks, taking into account significant aspects such as accuracy, stability, scalability, and on-line applicability.

Published
2009

11. Optimal volume anomaly detection in network traffic flows

Author

Fillatre, L., Igor Nikiforov, Casas, P., Vaton, S., Laboratoire Modélisation et Sûreté des Systèmes (LM2S), Institut Charles Delaunay (ICD), Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Troyes (UTT)-Centre National de la Recherche Scientifique (CNRS), Département informatique (INFO), and Université européenne de Bretagne - European University of Brittany (UEB)-Télécom Bretagne-Institut Mines-Télécom [Paris] (IMT)

Subjects
010104 statistics & probability, [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, 0202 electrical engineering, electronic engineering, information engineering, Computer Science::Networking and Internet Architecture, 020206 networking & telecommunications, 02 engineering and technology, 0101 mathematics, 01 natural sciences, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing
Abstract

International audience; Optimal detection of unusual and significant changes in network Origin-Destination (OD) traffic volumes from simple link load measurements is considered in the paper. The ambient traffic, i.e. the OD traffic matrix corresponding to the non-anomalous network state, is unknown and it is considered here as a nuisance parameter because it can mask the anomalies. Since the OD traffic matrix is not recoverable from simple link load measurements, the anomaly detection is an ill-posed decision-making problem. The method proposed in this paper consists of finding a linear parsimonious model of ambient traffic (nuisance parameter) and detecting anomalies by using an invariant detection algorithm based on a separation of the measurement space into disjoint subspaces corresponding to normal and anomalous network traffic. The method’s ability to detect anomalies is evaluated in real traffic from Abilene, a United States backbone network. The theoretically expected results are confirmed.

Published
2008

12. A new statistical approach to network anomaly detection

Author

CHRISTIAN CALLEGARI, Vaton, S., Pagano, M., TLC Network Research Group (TLCNETGRP), University of Pisa - Università di Pisa, Département informatique (INFO), Université européenne de Bretagne - European University of Brittany (UEB)-Télécom Bretagne-Institut Mines-Télécom [Paris] (IMT), and Télécom Bretagne (devenu IMT Atlantique), Ex-Bibliothèque

Subjects
[INFO.INFO-CR]Computer Science [cs]/Cryptography and Security [cs.CR], [STAT.AP]Statistics [stat]/Applications [stat.AP], [STAT.AP] Statistics [stat]/Applications [stat.AP], Intrusion detection system, High order Markov chain, Non-homogeneous Markov chain, Mixture transition model, [INFO.INFO-CR] Computer Science [cs]/Cryptography and Security [cs.CR], Computer Science::Cryptography and Security
Abstract

International audience; In the last few years, the number and impact of security attacks over the Internet have been continuously increasing. To face this issue, the use of Intrusion Detection Systems (IDSs) has emerged as a key element in network security. In this paper we address the problem considering a novel statistical technique for detecting network anomalies. Our approach is based on the use of different families of Markovian models (namely high order and non homogeneous Markov chains) for modeling network traffic running over TCP. The performance results shown in the paper, justify the proposed method and highlight the improvements over commonly used statistical techniques.

Published
2008

13. Hidden Markov modeling for network communication channels.

Author

Salamatian, K., Vaton, S., Salamatian, K., and Vaton, S.

Abstract

In this paper we perform the statistical analysis of an Internet communication channel. Our study is based on a Hidden Markov Model (HMM). The channel switches between different states; to each state corresponds the probability that a packet sent by the transmitter will be lost. The transition between the different states of the channel is governed by a Markov chain; this Markov chain is not observed directly, but the received packet flow provides some probabilistic information about the current state of the channel, as well as some information about the parameters of the model. In this paper we detail some useful algorithms for the estimation of the channel parameters, and for making inference about the state of the channel. We discuss the relevance of the Markov model of the channel; we also discuss how many states are required to pertinently model a real communication channel.

Published
2001

37. Improvement of cervical Chlamydia detection in asymptomatic family planning attendees by using Amplicor Chlamydia trachomatis assay.

Author

Chout R, Vaton S, Quist D, Bucher R, Leguyader-Desprees P, and Sayada C

Subjects
Adolescent, Adult, Ambulatory Care Facilities, Bacteriological Techniques statistics & numerical data, Chlamydia Infections microbiology, Evaluation Studies as Topic, Family Planning Services, Female, Humans, Polymerase Chain Reaction statistics & numerical data, Sensitivity and Specificity, Uterine Cervicitis microbiology, Chlamydia Infections diagnosis, Chlamydia trachomatis genetics, Chlamydia trachomatis isolation & purification, Polymerase Chain Reaction methods, Uterine Cervicitis diagnosis
Abstract

We evaluated the Amplicor C. trachomatis PCR assay (Roche Molecular Systems, N.J.) for the diagnosis of cervical infection in asymptomatic women attending a family planning clinic, aged between 18 and 25 years. Culture onto McCoy cells with fluorescent monoclonal staining was the reference system. Cervical specimens from 485 women were tested. The prevalence of C. trachomatis was 10.5% by culture and 11% by Amplicor. No specimen was positive by culture and negative by PCR. Three PCR-positive, culture-negative specimens were positive by MOMP-PCR and a second plasmid-based PCR. The resolved sensitivity of PCR and culture were 100% and 94.5%, respectively. Specificities for both were 100%, positive and negative predictive values for culture were 100% and 99.3%. Total test efficiency was 99.4%. The Amplicor C. trachomatis assay gave very clear results, quite above or below the cut-off value, and showed high sensitivity and specificity, improved ease of handling and represented a good alternative to culture for large scale diagnosis of asymptomatic C. trachomatis infection.

Published
1995

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