Naef. P. (In press). 1991-2011: Traces iconographiques des «Guerres Balkaniques». Essais en anthropologie visuelle. TSANTSA – Revue de la Société Suisse d’Ethnologie, Vol. 17
by Patrick Naef
La région des Balkans a connu des conflits armés violents dans les années quatre-vingt-dix et près de vingt ans après,... more La région des Balkans a connu des conflits armés violents dans les années quatre-vingt-dix et près de vingt ans après, les traces de la guerre sont encore visibles. Si les immeubles en ruines, les mines antipersonnelles, les impacts de balles et de mortiers disparaissent progressivement suivant un processus de reconstruction, certaines traces sont encore présentes, conservées volontairement ou laissées à l’abandon. De plus, certaines pratiques - muséales, artistiques, ou commerciales - participent à la mise en mémoire de ces guerres, par la production de graffitis, la vente de souvenirs ou encore la réalisation de divers projets artistiques. Cette contribution vise à exposer certaines représentations iconographiques de ces conflits, par l’exploration d’objets contemporains à ces guerres ou par la présentation d’éléments produits a posteriori. Les «roses de Sarajevo» (photo 1) - des impacts de mortiers remplis de peinture rouge et repérables dans différents endroits de la capitale bosnienne – peuvent déjà illustrer une forme de patrimonialisation et de mise en mémoire de la guerre.
Image Analysis for Cosmology: Results from the GREAT10 Galaxy Challenge
T. D. Kitching, S. T. Balan, S. Bridle, N. Cantale, F. Courbin, M. Gentile, M. S. S. Gill, S. Harmeling, C. Heymans, M. Hirsch, T. Kacprzak, D. Kirkby, D. Margala, R. J. Massey, P. Melchior, G. Nurbaeva, K. Patton, J. Rhodes, B. T. P. Rowe, A. N. Taylor, M. Tewes, M. Viola, D. Witherick, L. Voigt, J. Young, J. Zuntz, MNRAS, 2012
In this paper we present results from the weak lensing shape measurement GRavitational lEnsing Accuracy Testing 2010... more In this paper we present results from the weak lensing shape measurement GRavitational lEnsing Accuracy Testing 2010 (GREAT10) Galaxy Challenge. This marks an order of magnitude step change in the level of scrutiny employed in weak lensing shape measurement analysis. We provide descriptions of each method tested and include 10 evaluation metrics over 24 simulation branches. GREAT10 was the first shape measurement challenge to include variable fields; both the shear field and the Point Spread Function (PSF) vary across the images in a realistic manner. The variable fields enable a variety of metrics that are inaccessible to constant shear simulations including a direct measure of the impact of shape measurement inaccuracies, and the impact of PSF size and ellipticity, on the shear power spectrum. To assess the impact of shape measurement bias for cosmic shear we present a general pseudo-Cl formalism, that propagates spatially varying systematics in cosmic shear through to power spectrum estimates. We also show how one-point estimators of bias can be extracted from variable shear simulations. The GREAT10 Galaxy Challenge received 95 submissions and saw a factor of 3 improvement in the accuracy achieved by shape measurement methods. The best methods achieve sub-percent average biases. We find a strong dependence in accuracy as a function of signal-to-noise, and indications of a weak dependence on galaxy type and size. Some requirements for the most ambitious cosmic shear experiments are met above a signal-to-noise ratio of 20. These results have the caveat that the simulated PSF was a ground-based PSF. Our results are a snapshot of the accuracy of current shape measurement methods and are a benchmark upon which improvement can continue. This provides a foundation for a better understanding of the strengths and limitations of shape measurement methods.
Gravitational Lensing Accuracy Testing 2010 (GREAT10) Challenge Handbook
Thomas Kitching, Sreekumar Balan, Gary Bernstein, Matthias Bethge, Sarah Bridle, Frederic Courbin, Marc Gentile, Alan Heavens, Michael Hirsch, Reshad Hosseini, Alina Kiessling, Adam Amara, Donnacha Kirk, Konrad Kuijken, Rachel Mandelbaum, Baback Moghaddam, Guldariya Nurbaeva, Stephane Paulin-Henriksson, Anais Rassat, Jason Rhodes, Bernhard Schölkopf, John Shawe-Taylor, Mandeep Gill, Marina Shmakova, Andy Taylor, Malin Velander, Ludovic van Waerbeke, Dugan Witherick, David Wittman, Stefan Harmeling, Catherine Heymans, Richard Massey, Barnaby Rowe, Tim Schrabback, Lisa Voigt, Annals of Applied Statistics, 2011, 5, 3, 2231-2263
GRavitational lEnsing Accuracy Testing 2010 (GREAT10) is a public image analysis challenge aimed at the development of... more GRavitational lEnsing Accuracy Testing 2010 (GREAT10) is a public image analysis challenge aimed at the development of algorithms to analyze astronomical images. Specifically, the challenge is to measure varying image distortions in the presence of a variable convolution kernel, pixelization and noise. This is the second in a series of challenges set to the astronomy, computer science and statistics communities, providing a structured environment in which methods can be improved and tested in preparation for planned astronomical surveys. GREAT10 extends upon previous work by introducing variable fields into the challenge. The "Galaxy Challenge" involves the precise measurement of galaxy shape distortions, quantified locally by two parameters called shear, in the presence of a known convolution kernel. Crucially, the convolution kernel and the simulated gravitational lensing shape distortion both now vary as a function of position within the images, as is the case for real data. In addition, we introduce the "Star Challenge" that concerns the reconstruction of a variable convolution kernel, similar to that in a typical astronomical observation. This document details the GREAT10 Challenge for potential participants. Continually updated information is also available from http://www.greatchallenges.info.
Results of the GREAT08 Challenge: An image analysis competition for cosmological lensing
Sarah Bridle, Sreekumar T. Balan, Matthias Bethge, Marc Gentile, Stefan Harmeling, Catherine Heymans, Michael Hirsch, Reshad Hosseini, Mike Jarvis, Donnacha Kirk, Thomas Kitching, Konrad Kuijken, Antony Lewis, Stephane Paulin-Henriksson, Bernhard Scholkopf, Malin Velander, Lisa Voigt, Dugan Witherick, Adam Amara, Gary Bernstein, Frederic Courbin, Mandeep Gill, Alan Heavens, Rachel Mandelbaum, Richard Massey, Baback Moghaddam, Anais Rassat, Alexandre Refregier, Jason Rhodes, Tim Schrabback, John Shawe-Taylor, Marina Shmakova, Ludovic van Waerbeke, David Wittman, MNRAS, 2010, 405, 3, 2044-2061
We present the results of the Gravitational LEnsing Accuracy Testing 2008 (GREAT08) Challenge, a blind analysis... more We present the results of the Gravitational LEnsing Accuracy Testing 2008 (GREAT08) Challenge, a blind analysis challenge to infer weak gravitational lensing shear distortions from images. The primary goal was to stimulate new ideas by presenting the problem to researchers outside the shear measurement community. Six GREAT08 Team methods were presented at the launch of the Challenge and five additional groups submitted results during the 6-month competition. Participants analyzed 30 million simulated galaxies with a range in signal-to-noise ratio, point spread function ellipticity, galaxy size and galaxy type. The large quantity of simulations allowed shear measurement methods to be assessed at a level of accuracy suitable for currently planned future cosmic shear observations for the first time. Different methods perform well in different parts of simulation parameter space and come close to the target level of accuracy in several of these. A number of fresh ideas have emerged as a result of the Challenge including a re-examination of the process of combining information from different galaxies, which reduces the dependence on realistic galaxy modelling. The image simulations will become increasingly sophisticated in future GREAT Challenges, meanwhile the GREAT08 simulations remain as a benchmark for additional developments in shear measurement algorithms.
Handbook for the GREAT08 Challenge: An image analysis competition for cosmological lensing
Sarah Bridle, John Shawe-Taylor, Adam Amara, Douglas Applegate, Sreekumar T. Balan, Joel Berge, Gary Bernstein, Hakon Dahle, Thomas Erben, Mandeep Gill, Alan Heavens, Catherine Heymans, F. William High, Henk Hoekstra, Mike Jarvis, Donnacha Kirk, Thomas Kitching, Jean-Paul Kneib, Konrad Kuijken, David Lagatutta, Rachel Mandelbaum, Richard Massey, Yannick Mellier, Baback Moghaddam, Yassir Moudden, Reiko Nakajima, Stephane Paulin-Henriksson, Sandrine Pires, Anais Rassat, Alexandre Refregier, Jason Rhodes, Tim Schrabback, Elisabetta Semboloni, Marina Shmakova, Ludovic van Waerbeke, Dugan Witherick, Lisa Voigt, David Wittman, Annals of Applied Statistics, 2009,vol. 3, p. 6-37
The GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge focuses on a problem that is of crucial importance... more The GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge focuses on a problem that is of crucial importance for future observations in cosmology. The shapes of distant galaxies can be used to determine the properties of dark energy and the nature of gravity, because light from those galaxies is bent by gravity from the intervening dark matter. The observed galaxy images appear distorted, although only slightly, and their shapes must be precisely disentangled from the effects of pixelisation, convolution and noise. The worldwide gravitational lensing community has made significant progress in techniques to measure these distortions via the Shear TEsting Program (STEP). Via STEP, we have run challenges within our own community, and come to recognise that this particular image analysis problem is ideally matched to experts in statistical inference, inverse problems and computational learning. Thus, in order to continue the progress seen in recent years, we are seeking an infusion of new ideas from these communities. This document details the GREAT08 Challenge for potential participants. Please visit www.great08challenge.info for the latest information.
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Download (.1214v3)Oscillatory settling in wormlike-micelle solutions: bursts and a long time scale
by Nitin Kumar
Nitin Kumar, Sayantan Majumdar, Aditya Sood, Rama Govindarajan, Sriram Ramaswamy and A.K. Sood
Soft Matter, 2012, 8, 4310-4313
DOI: 10.1039/C2SM25077B
Preprint available here:
http://arxiv.org/pdf/1203.2130.pdf
We study the dynamics of a spherical steel ball falling freely through a solution of entangled wormlike-micelles. If... more We study the dynamics of a spherical steel ball falling freely through a solution of entangled wormlike-micelles. If the sphere diameter is larger than a threshold value, the settling velocity shows repeated short oscillatory bursts separated by long periods of relative quiescence. We propose a model incorporating the interplay of settling-induced flow, viscoelastic stress and, as in M. E. Cates, D. A. Head and A. Ajdari, Phys. Rev. E, 2002, 66, 025202(R) and A. Aradian and M. E. Cates, Phys. Rev. E, 2006, 73, 041508, a slow structural variable for which our experiments offer independent evidence.
Three-Dimensional Multiphase Segmentation of X-Ray CT Data of Porous Materials Using a Bayesian Markov Random Field Framework
"Co-authored with Markus Tuller, Wolfgang Fink and Dorthe Wildenschild", "published in 'Vadose Zone Journal', 2012"
Advancements in noninvasive imaging methods such as X-ray computed tomography (CT) have led to a recent surge of... more Advancements in noninvasive imaging methods such as X-ray computed tomography (CT) have led to a recent surge of applications in porous media research with objectives ranging from theoretical aspects of pore-scale fluid and interfacial dynamics to practical applications such as enhanced oil recovery and advanced contaminant remediation. While substantial efforts and resources have been devoted to advance CT technology, microscale analysis, and fluid dynamics simulations, the development of efficient and stable three-dimensional multiphase image segmentation methods applicable to large data sets is lacking. To eliminate the need for wet–dry or dual-energy scans, image alignment, and subtraction analysis, commonly applied in X-ray micro-CT, a segmentation method based on a Bayesian Markov random field (MRF) framework amenable to true three-dimensional multiphase processing was developed and evaluated. Furthermore, several heuristic and deterministic combinatorial optimization schemes required to solve the labeling problem of the MRF image model were implemented and tested for computational efficiency and their impact on segmentation results. Test results for three grayscale data sets consisting of dry glass beads, partially saturated glass beads, and partially saturated crushed tuff obtained with synchrotron X-ray micro-CT demonstrate great potential of the MRF image model for three-dimensional multiphase segmentation. While our results are promising and the developed algorithm is stable and computationally more efficient than other commonly applied porous media segmentation models, further potential improvements exist for fully automated operation.
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Image analysis: An inter-active approach to compositional elements
Co-authored with Derek Hook; forthcoming in Qualitative Research in Psychology
This article proposes an inter-active approach to the analysis of compositional elements of still visuals. This... more
This article proposes an inter-active approach to the analysis of compositional elements of still visuals. This approach stems from the argument that the rhetorical efficiency of images is related less to their content per se than to how this content is displayed and organised. As such, we start from the premise that images are ‘active’, performing the visual equivalent of speech-acts (i.e. ‘image-acts’) through which they construct the world and impact upon their viewers. In their turn, the audiences of an image participate in interpreting its meaning and responding to its particular ‘action’. This leads us to formulate a method based on the active engagement of researchers with the image at hand. We suggest a classification of compositional elements and identify ways in such elements can be analyzed and interpreted, casting light thus on the range of rhetorical and ideological effects that images so often achieve.
Keywords: image analysis, image-acts, inter-active method, compositional elements
A Study for Prediction of Minerals in Rock Images using Back Propagation Neural Networks
IEEE International Conference on Advances in Space Technologies (ICAST 2006) pp:185-189
This paper presents a novel approach for the segmentation of ground based images of rocks using back propagation... more This paper presents a novel approach for the segmentation of ground based images of rocks using back propagation neural network architecture. The designed system actually identifies the possible minerals by analyzing the surface color of the rocks. The rocks in Balochistan are very hard and defined. Such rocks are typically full of minerals. The rocks in the province of Balochistan are peculiar in their shape and surface colour. Usually, these colours are developed due to the reaction of the particles of the minerals with air. The upper layer of dust upon these rocks can be really useful in identifying the possible minerals concealing inside the rocks. The designed mechanism uses conventional artificial neural networks to identify various coloured parts of the rocks which are further classified into different minerals using histograms. The BPNN helps to learn to solve the task through a dynamic adaptation of its classification context. The designed system is trained by providing it the basic information related to the physical features of various mineral and types of rocks. The designed system highlights the various parts of the images by using various colours for various minerals.
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2D mapping of strongly deformable cell nuclei‐based on contour matching
J. De Vylder, W. De Vos, E. Manders and W. Philips.
Cytometry Part A, 79(7), 580-588, 2011.
The spatiotemporal dynamics of protein complexes and genome loci are functionally linked to cellular health status. To... more The spatiotemporal dynamics of protein complexes and genome loci are functionally linked to cellular health status. To study the inherent motion of subnuclear particles, it is essential to remove any superimposed component stemming from displacement and deformation of the nucleus. In this article, we propose a mapping of the nuclear interior, which is based on the deformation of the nuclear contour and has no shape constraints. This registration procedure enabled an accurate estimation of telomere mobility in living human cells undergoing dramatic nuclear deformations. Given the large variety of pathologies and cellular processes that are associated with strong nuclear shape changes, the contour mapping algorithm has generic value for improving the accuracy of mobility measurements of genome loci and intranuclear macromolecule complexes.
Time-resolved quantitative analysis of CCK1 receptor-induced intracellular calcium increase
D. Staljanssens, W. De Vos, P. Willems, J. Van Camp and G. Smagghe.
Peptides, epub ahead of print, 2011
Cholecystokinin (CCK) is a gastrointestinal hormone, which regulates many physiological functions such as satiety by... more Cholecystokinin (CCK) is a gastrointestinal hormone, which regulates many physiological functions such as satiety by binding to the CCK receptor (CCKR). Molecules, which recognize this receptor can mimic or block CCK signaling and thereby influence CCKR-mediated processes. We have set up a quantitative heterologous assay with CHO cells over-expressing the rat CCK1 receptor to screen for such candidate molecules. Receptor activation, induced by agonist binding, is followed by an intracellular calcium increase, which was monitored using a fluorescent sensor dye. For quantification of the calcium increase, a population average technique using a fluorescence plate reader was optimized and subsequently compared with a single-cell approach using confocal microscopy. With both strategies, dose-response curves were generated for the natural agonist CCK-8S, the partial agonist JMV-180 as well as the antagonist lorglumide. Significant differences were found between the ligands and a strong correspondence was observed between both methods in terms of maximum response and median effect concentrations. Both highly sensitive methods proved complementary: whereas the plate reader assay allowed faster, high throughput screening, the confocal microscopy identified single-cell variations and revealed factors that reduce specificity and sensitivity.
High Content Image Cytometry: A Versatile Tool for Mapping Subnuclear Organization
W. De Vos, E. Manders and P. Van Oostveldt
Imaging and Microsopy 4, p46-48, 2009.
The human eye is a powerful and sensitive instrument which excels in pattern recognition, by using mental templates to... more The human eye is a powerful and sensitive instrument which excels in pattern recognition, by using mental templates to identify and categorize objects. Unfortunately, its exact strength may also be its weakness, for it implies a certain subjectivity to the interpretation of images. Furthermore, our distinctive power and vocabulary for describing objects in a quantitative manner are limited. Accurate visualization and characterization of cellular features thus calls for a more objective approach, which can now be provided by the fast growing discipline of high content image cytometry (HCIC).
High content analysis of human fibroblast cell cultures after exposure to space radiation
B. Dieriks(1), W. De Vos(1), G. Meesen, K. Van Oostveldt, M. Ghardi, S. Baatout and P. Van Oostveldt.
Radiation Research 172(4), p423-436, 2009
(1equal contribution, first author)
Space travel imposes risks to human health, in large part by the increased radiation levels compared to those on... more Space travel imposes risks to human health, in large part by the increased radiation levels compared to those on Earth. To understand the effects of space radiation on humans, it is important to determine the underlying cellular mechanisms. While general dosimetry describes average radiation levels accurately, it says little about the actual physiological impact and does not provide biological information about individual cellular events. In addition, there is no information about the nature and magnitude of a systemic response through extra- and intercellular communication. To assess the stress response in human fibroblasts that were sent into space with the Foton-M3 mission, we have developed a pluralistic setup to measure DNA damage and inflammation response by combining global and local dosimetry, image cytometry and multiplex array technology, thereby maximizing the scientific output. We were able to demonstrate a significant increase in DNA double-strand breaks, determined by a twofold increase of the gamma-H2AX signal at the level of the single cell and a threefold up-regulation of the soluble signal proteins CCL5, IL-6, IL-8, beta-2 microglobulin and EN-RAGE, which are key players in the process of inflammation, in the growth medium.