Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailQuantifying and Mitigating IGMP Filtering in Topology Discovery
Marchetta, Pietro; Mérindol, Pascal; Donnet, Benoît ULg et al

in IEEE Global Communications Conference (GLOBECOM) (2012, December)

Recent developments in router level topology discovery have suggested the introduction of IGMP probing in addition to standard techniques such as traceroute and alias resolution. With a single IGMP probe ... [more ▼]

Recent developments in router level topology discovery have suggested the introduction of IGMP probing in addition to standard techniques such as traceroute and alias resolution. With a single IGMP probe, one can obtain all multicast interfaces and links of a multicast router. If such a probing is a promising approach, we noticed that IGMP probes are subject to filtering, leading so to the fragmentation of the collected multicast graph into several disjoint connected components. In this paper, we cope with the fragmentation issue. Our contributions are threefold: (i) we experimentally quantify the damages caused by IGMP filtering on collected topologies of large tier-1 ISPs; (ii) using traceroute data, we construct a hybrid graph and estimate how far each IGMP fragment is from each other; (iii) we provide and experimentally evaluate a recursive approach for reconnecting disjoint multicast components. The key idea of the third contribution is to recursively apply alias resolution to reassemble disjoint fragments and, thus, progressively extend the mapping of the targeted ISP. Data presented in the paper, as well as reconstructed topologies, are freely available at http://svnet.u-strasbg.fr/merlin. [less ▲]

Detailed reference viewed: 66 (14 ULg)
Full Text
Peer Reviewed
See detailQuantifying ASes Multiconnectivity Using Multicast Information
Mérindol, Pascal; Van den Schriek, Virginie; Donnet, Benoît ULg et al

in 9th ACM SIGCOMM Conference on Internet Measurement (2009, November)

Redundant connectivity (or multiconnectivity) between adjacent autonomous systems (ASes) is important for inter-domain traffic engineering and fast recovery in case of failures. However, the redundancy of ... [more ▼]

Redundant connectivity (or multiconnectivity) between adjacent autonomous systems (ASes) is important for inter-domain traffic engineering and fast recovery in case of failures. However, the redundancy of ASes business relationship links has not been quantitatively studied, mainly due to the difficulty of obtaining relevant data. In this paper, we show that the mrinfo multicast monitoring tool can provide useful data about the Internet topology and such redundant links in particular. Our analysis relies on more than four years of daily queries to about ten thousand routers mapped into more than two hundred ASes. We demonstrate that peering links between ASes are frequently redundant. In particular, our analysis shows that more than half of the studied ASes pairs are connected through multiple physical links. We then refine our analysis by considering the different types of ASes and their business relationships. A particular result of our analysis is that at least 75% of the peer-to-peer relationships between adjacent Tier-1 ASes are redundant, i.e., the con- nections between these ASes involve several physical links. Our analysis is conservative, providing so a lower bound, as some links might not be seen by mrinfo due to ISPs filtering policies. [less ▲]

Detailed reference viewed: 11 (4 ULg)
Full Text
Peer Reviewed
See detailQuantifying consciousness
Laureys, Steven ULg; Piret, Sonia ULg; Ledoux, Didier ULg

in Lancet Neurology (2005), 4(12), 789-790

Detailed reference viewed: 47 (2 ULg)
Full Text
See detailQuantifying cortical EEG responses to TMS in (un)consciousness
Sarasso, S; Rosanova, M; Casali, A.G et al

in Clinical EEG and Neuroscience : Official Journal of the EEG and Clinical Neuroscience Society (ENCS) (2014)

We normally assess another individual's level of consciousness based on her or his ability to interact with the surrounding environment and communicate. Usually, if we observe purposeful behavior ... [more ▼]

We normally assess another individual's level of consciousness based on her or his ability to interact with the surrounding environment and communicate. Usually, if we observe purposeful behavior, appropriate responses to sensory inputs, and, above all, appropriate answers to questions, we can be reasonably sure that the person is conscious. However, we know that consciousness can be entirely within the brain, even in the absence of any interaction with the external world; this happens almost every night, while we dream. Yet, to this day, we lack an objective, dependable measure of the level of consciousness that is independent of processing sensory inputs and producing appropriate motor outputs. Theoretically, consciousness is thought to require the joint presence of functional integration and functional differentiation, otherwise defined as brain complexity. Here we review a series of recent studies in which Transcranial Magnetic Stimulation combined with electroencephalography (TMS/EEG) has been employed to quantify brain complexity in wakefulness and during physiological (sleep), pharmacological (anesthesia) and pathological (brain injury) loss of consciousness. These studies invariably show that the complexity of the cortical response to TMS collapses when consciousness is lost during deep sleep, anesthesia and vegetative state following severe brain injury, while it recovers when consciousness resurges in wakefulness, during dreaming, in the minimally conscious state or locked-in syndrome. The present paper will also focus on how this approach may contribute to unveiling the pathophysiology of disorders of consciousness affecting brain-injured patients. Finally, we will underline some crucial methodological aspects concerning TMS/EEG measurements of brain complexity. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailQuantifying flood damages for climate-change adaptation on a transnational river basin
Fournier, Maïté; Sinaba, Benjamin; Dewals, Benjamin ULg et al

in Schüttrumpf (Ed.) Floods: a permanent challenge! (2012)

The Meuse river basin is shared by five countries. Climate change in the future decades could either lead to a dryer or a wetter situation. In order to build an adaptation strategy that would cope with ... [more ▼]

The Meuse river basin is shared by five countries. Climate change in the future decades could either lead to a dryer or a wetter situation. In order to build an adaptation strategy that would cope with both scenarios and that is agreed at the international level, water experts have set-up the AMICE project. Quantifying the flood damages is an important part of this project. It required much negotiation at every intermediary step, from the definition of climate scenarios, to the hydraulic modeling and the agreement on damage functions. [less ▲]

Detailed reference viewed: 48 (2 ULg)
Peer Reviewed
See detailQuantifying habitat edge for nature reserve design.
Bogaert, Jan ULg; Van Hecke, P; Salvador-Van Eysenrode, D et al

in Coenoses (1998), 13(3), 131-136

Detailed reference viewed: 3 (2 ULg)
Peer Reviewed
See detailQuantifying hand cross contamination in food.
Rodrigues, Ana; Dure, Rémi ULg; Delhalle, Laurent ULg et al

Poster (2009, June)

Detailed reference viewed: 14 (0 ULg)
Full Text
Peer Reviewed
See detailQuantifying Input Uncertainty in Traffic Assignment Models
Perrakis, Konstantinos; Cools, Mario ULg; Karlis, Dimitris et al

in Proceedings of the 91st Annual Meeting of the Transportation Research Board (DVD-ROM) (2012)

Traffic assignment methods distribute Origin-Destination (OD) flows throughout the links of a given network according to procedures related to specific deterministic or stochastic modeling assumptions. In ... [more ▼]

Traffic assignment methods distribute Origin-Destination (OD) flows throughout the links of a given network according to procedures related to specific deterministic or stochastic modeling assumptions. In this paper, we propose a methodology that enhances the information provided from traffic assignment models, in terms of delivering stochastic estimates for traffic flows on links. Stochastic variability is associated to the initial uncertainty related to the OD matrix used as input into a given assignment method, and therefore the proposed methodology is not constrained by the choice of the assignment model. The methodology is based on Bayesian estimation methods which provide a suitable working framework for generating multiple OD matrices from the corresponding predictive distribution of a given statistical model. Predictive inference for link flows is then straightforward to implement, either by assigning summarized OD information or by performing multiple assignments. Interesting applications arise in a natural way from the proposed methodology, as is the identification and evaluation of critical links by means of probability estimates. A real-world application is presented for the road network of the northern, Dutch-speaking region of Flanders in Belgium, under the assumption of a deterministic user equilibrium model. [less ▲]

Detailed reference viewed: 16 (0 ULg)
Full Text
See detailQuantifying intra-urban morphology of the Greater Dublin area with spatial metrics derived from medium resolution remote sensing data
Van de Voorde, Tim; van der Kwast, Johannes; Engelen, Guy et al

in IEEE Proceedings of the 7th International Urban Remote Sensing Conference : Shanghai, May 20-22, 2009 (2009)

Spatial metrics derived from satellite imagery are useful measures to quantify structural characteristics of expanding cities, and can provide indications of functional land use types. Images of medium ... [more ▼]

Spatial metrics derived from satellite imagery are useful measures to quantify structural characteristics of expanding cities, and can provide indications of functional land use types. Images of medium resolution are cheap, widely available and are often part of extensive historic archives. Their lower resolution, on the other hand, inhibits studying urban morphology and change processes at a more detailed, intra-urban level. In this study, we develop spatial metrics for use on continuous sealed surface data produced by a sub-pixel classification of Landsat ETM+ imagery. The metrics characterise the shape of the cumulative frequency distribution of the estimated sub-pixel fractions within a building block by fitting an exponential and a sigmoid function with a least-squares approach. A classification tree is then used to relate the metric variables to urban land-use classes selected from the European MOLAND topology. This approach shows promising results, but still needs improvement which may be achieved by including spatially explicit metrics in the analysis. [less ▲]

Detailed reference viewed: 140 (22 ULg)
Full Text
Peer Reviewed
See detailQuantifying lymphocyte kinetics in vivo using carboxyfluorescein diacetate succinimidyl ester (CFSE).
Asquith, Becca; Debacq, Christophe; Florins, Arnaud-Francois ULg et al

in Proceedings of the Royal Society B : Biological Sciences (2006), 273(1590), 1165-71

The cytoplasmic dye carboxyfluorescein diacetate succinimidyl ester (CFSE) is used to quantify cell kinetics. It is particularly important in studies of lymphocyte homeostasis where its labelling of cells ... [more ▼]

The cytoplasmic dye carboxyfluorescein diacetate succinimidyl ester (CFSE) is used to quantify cell kinetics. It is particularly important in studies of lymphocyte homeostasis where its labelling of cells irrespective of their stage in the cell cycle makes it preferable to deuterated glucose and BrdU, which only label dividing cells and thus produce unrepresentative results. In the past, experiments have been limited by the need to obtain a clear separation of CFSE peaks forcing scientists to adopt a strategy of in vitro labelling of cells followed by their injection into the host. Here we develop a framework for analysis of in vivo CFSE labelling data. This enables us to estimate the rate of proliferation and death of lymphocytes in situ, and thus represents a considerable advance over current procedures. We illustrate this approach using in vivo CFSE labelling of B lymphocytes in sheep. [less ▲]

Detailed reference viewed: 51 (20 ULg)
Peer Reviewed
See detailQuantifying scale-dependent effects of cove-dwellers movements with connectivity models
Henry, Valérie ULg; Tercafs, R.

in Mémoires de Biospéologie (1999), XXVI

Detailed reference viewed: 1 (0 ULg)
Full Text
Peer Reviewed
See detailQuantifying the sorting efficiency of self-propelled run-and-tumble swimmers by geometrical ratchets
Berdakin; Silhanek, Alejandro ULg; Moyano Cortéz, H. N. et al

in Central European Journal of Physics (2013)

Suitable asymmetric microstructures can be used to control the direction of motion in microorganism populations. This rectification process makes it possible to accumulate swimmers in a region of space or ... [more ▼]

Suitable asymmetric microstructures can be used to control the direction of motion in microorganism populations. This rectification process makes it possible to accumulate swimmers in a region of space or to sort different swimmers. Here we study numerically how the separation process depends on the specific motility strategies of the microorganisms involved. Crucial properties such as the separation effi ciency and the separation time for two bacterial strains are precisely defined and evaluated. In particular, the sorting of two bacterial populations inoculated in a box consisting of a series of chambers separated by columns of asymmetric obstacles is investigated. We show how the sorting e fficiency is enhanced by these obstacles and conclude that this kind of sorting can be effi ciently used even when the involved populations differ only in one aspect of their swimming strategy. [less ▲]

Detailed reference viewed: 27 (2 ULg)
Full Text
Peer Reviewed
See detailQuantifying trait selection driving community assembly: a test in herbaceous plant communities under contrasted land use regimes
Sonnier, Grégory; Navas, Marie-Laure; Fayolle, Adeline ULg

in Oikos (2012), 121(7), 1103-1111

Plant traits are particularly important in determining plant community structure. However, how can one identify which traits are the most important in driving community assembly? Here we propose a method ... [more ▼]

Plant traits are particularly important in determining plant community structure. However, how can one identify which traits are the most important in driving community assembly? Here we propose a method 1) to quantify the direction and strength of trait selection during community assembly and 2) to obtain parsimonious lists of traits that can predict species relative bundances in plant communities. We tested our method using floristic data from 32 plots experiencing different treatments (fertilisation and grazing) in southern France. Twelve functional traits were measured on 68 species. We determined the direction and strength of selection on these 12 traits using a metric derived from a maximum entropy model (i.e. lambda). We then determined our parsimonious list of traits using a backward selection of traits based on these lambda values (for all treatments and in each treatment separately). We finally compared our method to two other methods: one based on iterative RLQ and the other based on an entropy-based forward selection of traits. We found major differences in the direction and strength of selection across the 12 traits and treatments. From the 12 traits, plant vegetative and reproductive heights, leaf dry matter content leaf nitrogen content, specific leaf area, and leaf phosphorus content were particularly important for predicting species relative abundances when considering all treatments together. Our method yielded results similar to those produced by the entropy-based approach but differed from those produced by the iterative RLQ, whose selected traits could not significantly predict species relative abundances. Together these results suggest that the assembly of these communities is primarily driven by a small number of key functional traits. We argue that our method provides an objective way of determining a parsimonious list of traits that together accurately predict community structure and which, despite its complementarities with entropy-based method, offers significant advantages. [less ▲]

Detailed reference viewed: 22 (2 ULg)
Peer Reviewed
See detailQuantile regression in nonparametric location-scale models with censored data
Heuchenne, Cédric ULg; Van Keilegom, Ingrid

Conference (2011, December)

Detailed reference viewed: 24 (0 ULg)
Full Text
Peer Reviewed
See detailQuantitation of Functional Mitral Regurgitation During Bicycle Exercise in Patients with Heart Failure
Lebrun, F.; LANCELLOTTI, Patrizio ULg; PIERARD, Luc ULg

in Journal of the American College of Cardiology (2001), 38(6), 1685-92

OBJECTIVES: We sought to examine the feasibility and reliability of quantifying mitral regurgitation (MR) during exercise by Doppler echocardiography in patients with heart failure and to assess the ... [more ▼]

OBJECTIVES: We sought to examine the feasibility and reliability of quantifying mitral regurgitation (MR) during exercise by Doppler echocardiography in patients with heart failure and to assess the relationship between dynamic MR and systolic pulmonary artery pressure changes. BACKGROUND: The severity of MR can be quantified by using several echocardiographic methods. Quantitation of MR during dynamic exercise has not yet been performed. METHODS: Symptom-limited, semi-supine two-dimensional and Doppler echocardiograms during bicycle exercise were obtained in 27 consecutive patients with heart failure and functional MR. Regurgitant volume was measured at rest and during exercise by the proximal isovelocity surface area (PISA) method and by quantitative Doppler echocardiography. Exercise-induced changes in regurgitant volume were compared with changes in the regurgitant jet area to left atrial area ratio, vena contracta width and trans-tricuspid pressure gradient. RESULTS: The regurgitant volume measured by the PISA method increased from 21 +/- 12 ml (range 5 to 55) at rest to 39 +/- 23 ml (range 8 to 85) during exercise (p < 0.0001). The difference between two observers was low for both rest (2.0 +/- 2.7 ml) and exercise measurements (3.5 +/- 6.2 ml). The regurgitant volume measured by quantitative Doppler echocardiography increased from 29 +/- 13 to 49 +/- 24 ml (p = 0.0001). Excellent correlation between the two methods was obtained with exercise (r = 0.92). Exercise-induced changes in regurgitant volume, as measured by the PISA method, correlated well with regurgitant volume changes measured by quantitative Doppler echocardiography (r = 0.88), changes in vena contracta width (r = 0.82) and changes in trans-tricuspid pressure gradient (r = 0.73), but not with changes in regurgitant jet area to left atrial area ratio (r = 0.29). Seventeen patients stopped exercise because of fatigue and 10 because of dyspnea. These 10 patients exhibited greater increases in regurgitant volume (34 +/- 6 vs. 11 +/- 8 ml), corresponding to a significant elevation of the trans-tricuspid gradient (48 +/- 14 vs. 20 +/- 14 mm Hg). CONCLUSIONS: Quantitation of functional MR during exercise is feasible in patients with heart failure. There is a good correlation between regurgitant volume measured during exercise by the PISA method and that obtained by quantitative Doppler echocardiography, suggesting that the technique is reliable. An increase in mitral regurgitant volume during dynamic exercise correlates well with elevation of systolic pulmonary artery pressure. [less ▲]

Detailed reference viewed: 8 (2 ULg)
Full Text
Peer Reviewed
See detailQuantitative accelerated life testing of MEMS accelerometers
Bazu, Marius; Gălăţeanu, Lucian; Ilian, Virgil Emil et al

in sensors (2007), 7(11), 2846

Quantitative Accelerated Life Testing (QALT) is a solution for assessing the reliability of Micro Electro Mechanical Systems (MEMS). A procedure for QALT is shown in this paper and an attempt to assess ... [more ▼]

Quantitative Accelerated Life Testing (QALT) is a solution for assessing the reliability of Micro Electro Mechanical Systems (MEMS). A procedure for QALT is shown in this paper and an attempt to assess the reliability level for a batch of MEMS accelerometers is reported. The testing plan is application-driven and contains combined tests: thermal (high temperature) and mechanical stress. Two variants of mechanical stress are used: vibration (at a fixed frequency) and tilting. Original equipment for testing at tilting and high temperature is used. Tilting is appropriate as application-driven stress, because the tilt movement is a natural environment for devices used for automotive and aerospace applications. Also, tilting is used by MEMS accelerometers for anti-theft systems. The test results demonstrated the excellent reliability of the studied devices, the failure rate in the “worst case” being smaller than 10-7h-1. [less ▲]

Detailed reference viewed: 35 (3 ULg)
See detailQuantitative analyses of diachronic developments of the function of subordinators : The case of Old Nordic word order
Zeevaert, Ludger ULg; Wörner, Kai; Höder, Steffen

Book published by Sonderforschungsbereich Mehrsprachigkeit (2007)

Detailed reference viewed: 10 (0 ULg)