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See detailPattern Recognition in NeuroImaging: What can machine learning classifiers bring to the analysis of functional brain imaging?
Schrouff, Jessica ULg

Doctoral thesis (2013)

The study of the brain development and functioning raises many question that are tracked using neuroimaging techniques such as positron emission tomography or (functional) magnetic resonance imaging ... [more ▼]

The study of the brain development and functioning raises many question that are tracked using neuroimaging techniques such as positron emission tomography or (functional) magnetic resonance imaging. During the last decades, various techniques have been developed to analyse neuroimaging data. These techniques brought valuable insight on neuroscientific questions, but encounter limitations which make them unsuitable to tackle more complex problems. More recently, machine learning based models, coming from the field of pattern recognition, have been promisingly applied to neuroimaging data. In this work, the assets and limitations of machine learning based models were investigated and compared to previously developed techniques. To this end, two applications involving challenging datasets were defined and the results from widespread methods were compared to the results obtained using machine learning based modelling. More specifically, the first application addressed a research question: Is it possible to detect and characterize mnemonic traces? The fMRI experiment comprised a learning and a control tasks, both flanked by rest sessions. From previous studies, patterns of brain activity generated during the learning task should be spontaneously repeated during the following rest session, while no difference should be observed between the pre- and post-task rest session in the control condition. Using univariate and multivariate feature selection steps before a Gaussian Processes classification, mnemonic traces could be detected and their spatio-temporal evolution characterized. On the contrary, an analysis of the rest sessions based on the detection of independent networks did not provide any results supporting the theory of memory consolidation. The second application tackled a clinical issue: Can a pattern of brain activation characteristic to idiopathic Parkinson’s disease be detected and localized? The dataset considered to address this question comprised the fMRI images of aged healthy subjects and Parkinsonian patients while they were performing a task of mental imagery of gait at three different paces. The signal comprised in a priori selected regions of interest allowed for the support vector machines classification of healthy and diseased volunteers with an accuracy of 86%. To localize the discriminating pattern, a methodology based on the weight in labelled regions (e.g. from the anatomical automatic labelling or Brodmann atlases) was developed, which enabled the comparison between univariate and multivariate results and showed a nice overlap between them. Furthermore, models could then be compared quantitatively in terms of pattern localization, using a specifically defined measure of distance. This measure could then be used to compare the patterns generated from different folds of a same model, from different feature sets, or from different modelling techniques. The present study concluded that machine learning models can clearly and fruitfully complement other analysis techniques to tackle challenging questions in neuroscience. On the other hand, more work is needed in order to render the methodology fully accessible to the neuroscientific community. [less ▲]

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See detailPattern recognition with a digital holographic microscope working in partially coherent illumination
Dubois, Frank; Minetti, Christophe; Monnom, Olivier et al

in Applied Optics (2002), 41(20), 4108-4119

We describe the implementation of the automatic spatial-frequency-selection filter for recognition of patterns obtained with a digital holographic microscope working with a partially coherent source. The ... [more ▼]

We describe the implementation of the automatic spatial-frequency-selection filter for recognition of patterns obtained with a digital holographic microscope working with a partially coherent source. The microscope provides the complex-optical-amplitude field that allows a refocusing plane-by-plane of the sample under investigation by numerical computation of the optical propagation. By inserting a correlation filter in the propagation equation, the correlation between the filter and the propagated optical field is obtained. In this way, the pattern is located in the direction of the optical axis. Owing to the very weak noise level generated by the partially coherent source, the correlation process is shift invariant. Therefore the samples can be located in the three dimensions. To have a robust recognition process, a generalized version of the automatic spatial-frequency-selection filters has been implemented. The method is experimentally demonstrated in a two-class problem for the recognition of protein crystals. (C) 2002 Optical Society of America. [less ▲]

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See detail'Pattern' comportemental de type A : stress et maladie coronarienne : II. Aspects pratiques
Etienne, Anne-Marie ULg; Fontaine, Ovide ULg

in Revue Médicale de Liège (1994), XLIX(1), 36-48

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See detailPattern-learning and pattern-description : An integrated approach to proficiency and research for students of English
Brems, Lieselotte ULg; Olivier, Nele

in Corpora in the foreign language classroom. Selected papers from the Sixth International Conference on Teaching and Language Corpora (TaLC) (2007)

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See detailPatterns in hydraulic ripples with binary granular mixtures
Caps, Hervé ULg; Vandewalle, Nicolas ULg

in Physica A: Statistical Mechanics and its Applications (2002), 313(3-4), 357-364

An experimental study of a binary granular mixture submitted to a transient shear flow in a cylindrical container is reported. The formation of ripples with a spiral shape is observed. The appearance of ... [more ▼]

An experimental study of a binary granular mixture submitted to a transient shear flow in a cylindrical container is reported. The formation of ripples with a spiral shape is observed. The appearance of phase segregation in those spiral patterns is shown. The relative grain size between sand species is found to be a relevant parameter leading to phase segregation. However, the relative repose angle is an irrelevant parameter. The formation of sedimentary structures is also presented. They result from a ripple climbing process. The "sub-critical" or "super-critical" character of the lamination patterns is shown to depend on the rotation speed of the container. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailPatterns in national policies for support of low achievers in reading across Europe
Motiejunaite, Akvile; Noorani, Sogol; Monseur, Christian ULg

in British Educational Research Journal (2014)

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See detailPatterns of allozymic variation within Calluna vulgaris populations at seed bank and adult stages
Mahy, Grégory ULg; Vekemans, Xavier; Jacquemart, Anne Laure

in Heredity (1999), 82

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See detailPatterns of aluminum hydroxychloride deposition onto the skin.
Mayeux, Geraldine; Xhauflaire-Uhoda, Emmanuelle; PIERARD, Gérald ULg

in Skin Research & Technology (2012), 18(1), 64-9

BACKGROUND: Aluminum hydroxychloride (AlCl(3) ) is an antiperspirant. AIM: To revisit the AlCl(3) deposition in vivo and in vitro on glass slides and stratum corneum (SC) harvested by cyanoacrylate skin ... [more ▼]

BACKGROUND: Aluminum hydroxychloride (AlCl(3) ) is an antiperspirant. AIM: To revisit the AlCl(3) deposition in vivo and in vitro on glass slides and stratum corneum (SC) harvested by cyanoacrylate skin surface strippings (CSSS). METHODS: Transepidermal water loss (TEWL) was assessed following application of 5% AlCl(3) on the forearms. The AlCl(3) -coated skin, glass slides and CSSS were observed using two ultraviolet light-emitting CCD cameras in order to record changes in specular reflectance related to AlCl(3) deposition. In addition, the corneoxenometry bioassay was performed in order to predict AlCl(3) irritation. RESULTS: AlCl(3) deposited on glass slides looked as linear threads and rings of similar sizes. AlCl(3) deposits on skin were almost restricted inside the microrelief lines and as annular deposits at their crossings where acrosyringia are opening. After daily AlCl(3) applications, deposits extended on the CSSS plateaus. At rest in absence of sweating, TEWL was decreased following AlCl(3) applications. During physical exercise, the TEWL increase was limited on the AlCl(3) areas. CSSS appeared unreactive to AlCl(3) at the corneoxenometry bioassay. CONCLUSION: The similar aspect of AlCl(3) deposits on human SC and on glass slides suggested a physical property of AlCl(3) . Repetitive applications of AlCl(3) increased both the deposit area and the barrier function. [less ▲]

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See detailPatterns Of Bryophyte Diversity And Rarity At A Regional Scale
Vanderpoorten, Alain ULg; Engels, Patrick ULg

in Biodiversity & Conservation (2003), 12(3),

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See detailPatterns of Clinical Management and Resource Utilisation for Postmenopausal Hormone-Receptor-Positive HER2-Negative (HR+ HER2-) Advanced Breast Cancer (BC) in Europe
ANDRE, Fabrice; MARINSEK, Nina; RICCI, Jean-François et al

in Value in Health (2012, November), 15(7), 419

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See detailPatterns of crop damage by wild boar (Sus scrofa)in Luxembourg over a 10-year period
Schley, L.; Dufrêne, Marc ULg; Krier, A. et al

in European Journal of Wildlife Research (2008), 54(4), 589-599

In many European countries, the wild boar (Sus scrofa) is often associated with crop damage. In this study, we analyse data relating to 13,276 cases of wild boar damage to agricultural crops over a 10 ... [more ▼]

In many European countries, the wild boar (Sus scrofa) is often associated with crop damage. In this study, we analyse data relating to 13,276 cases of wild boar damage to agricultural crops over a 10-year period in Luxembourg (an area of 2,586 km2 in Western Europe). Results show that (1) damage is more severe in this area than in others; (2) damage to permanent grassland is far more frequent and more severe than damage to annual crops; (3) trichomatous crops such as barley are avoided; (4) damage is seasonally distributed according to type of crop; (5) damage is distributed spatially in a non-uniform manner; (6) damage intensity is significantly correlated with wild boar hunting bags, both over time and space. We suggest that wild boar management strategy should always take into account the issue of damage to agricultural crops. Our results imply that measures for preventing or reducing damage should be more targeted in time and space and that adjustments to cropping patterns should contribute towards a reduction of wild boar damage. © 2008 Springer-Verlag. [less ▲]

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See detailPatterns of difficult cases for breast irradiation: where multi-beam IMRT and SIB should be the primary choice
Ben Mustapha, S.; Dechambre, D.; Mievis, C. et al

in Radiother Oncol (2014), ESTRO 33

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See detailPatterns of diversification in early eukaryotes
Javaux, Emmanuelle ULg

in Steemans, Philippe; Javaux, Emmanuelle (Eds.) Recent advances in palynology (2007)

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See detailPatterns of early eukaryote diversification
Javaux, Emmanuelle ULg

Conference (2006)

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See detailPatterns of genomic aberrations suggest that Burkitt lymphomas with complex karyotype are distinct from other aggressive B-cell lymphomas with MYC rearrangement.
Havelange, Violaine; Ameye, Genevieve; Theate, Ivan et al

in Genes, Chromosomes & Cancer (2013), 52(1), 81-92

We previously showed that complex karyotypes (CK) and chromosome 13q abnormalities have an adverse prognostic impact in childhood Burkitt lymphomas/leukemias (BL) and diffuse large B-cell lymphomas (DLBCL ... [more ▼]

We previously showed that complex karyotypes (CK) and chromosome 13q abnormalities have an adverse prognostic impact in childhood Burkitt lymphomas/leukemias (BL) and diffuse large B-cell lymphomas (DLBCL). The aim of our study was to identify recurrent alterations associated with MYC rearrangements in aggressive B-cell lymphomas with CK. Multicolor fluorescence in situ hybridization (M-FISH) was performed in 84 patient samples (59 adults and 25 children), including 37 BL (13 lymphomas and 24 acute leukemias), 12 DLBCL, 28 B-cell lymphomas with intermediate features (DLBCL/BL), 4 B-cell precursor acute lymphoblastic leukemias (BCP-ALL), and 3 unclassifiable B-cell lymphomas. New (cytogenetically undetected) abnormalities were identified in 80% of patients. We also refined one-third of the chromosomal aberrations detected by karyotyping. M-FISH proved to be more useful in identifying chromosomal partners involved in unbalanced translocations and in revealing greater complexity of 13q rearrangements. Most of the newly identified or refined recurrent alterations involved 1q, 13q and 3q (gains/losses), 7q and 18q (gains), or 6q (losses), suggesting that these secondary aberrations may play a role in lymphomagenesis. Several patterns of genomic aberrations were identified: 1q gains in BL, trisomies 7 in DLBCL, and 18q-translocations in adult non-BL. BCP-ALL usually displayed an 18q21 rearrangement. BL karyotypes were less complex and aneuploid than those of other MYC-rearranged lymphomas. BCP-ALL and DLBCL/BL were associated with a higher rate of early death than BL and DLBCL. These findings support the categorization of DLBCL/BL as a distinct entity and suggest that BL with CK are indeed different from other aggressive MYC-rearranged lymphomas, which usually show greater genetic complexity. (c) 2012 Wiley Periodicals, Inc. [less ▲]

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See detailPatterns of hybridization and hybrid survival in the invasive alien Fallopia complex (Polygonaceae)
Saad, Layla ULg; Tiébré, Marie-Solange; Hardy, Olivier et al

in Plant Ecology and Evolution (2011), 144(12-18),

Background -- Hybridization and polyploidization are considered important driving forces of invasive processes. In the invasive Fallopia spp. complex, hybridization between taxa of various ploidy levels ... [more ▼]

Background -- Hybridization and polyploidization are considered important driving forces of invasive processes. In the invasive Fallopia spp. complex, hybridization between taxa of various ploidy levels has been experimentally demonstrated. Extensive genetic variation has also been observed among hybrids in the field. However, what makes a certain hybridization event of evolutionary importance is still the subject of speculation considering the invasive potential of hybrid Fallopia. Aims -- The present study examined landscape scale patterns of interspecific hybridization within the alien invasive Fallopia complex, and tested whether cold winter might act as selective agent for hybrid survival. Methods -- Eighty seeds per clone were collected from four taxa (F. japonica, F. sachalinensis, F. aubertii, and F. xbohemica) and sown in greenhouse and outdoor conditions. Ploidy levels of the resulting seedlings were determined by flow cytometry at early stages of seedling growth and compared to those of mature clones present in the same landscapes. Key results -- The four studied taxa were involved in interspecific hybridization patterns. Seedlings resulting from hybridization had a large range of ploidy levels, including aneuploid and euploid progeny, and polyploid levels that were not observed in mature clones. Cold winter had a negative effect on germination success. However, a comparison of ploidy levels of seedlings that survived the cold winter with those grown under greenhouse conditions indicated that cold winter was not a significant selection agent for particular ploidy levels. Conclusions -- Our results stress the importance of interspecific hybridization and polyploidization events in generating invasive hybrids in the alien Fallopia spp complex. Cold winter represents a selection agent for the survival of early stages of progeny but does not explain the discrepancies in ploidy levels between produced seedlings and currently occurring mature clones. [less ▲]

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