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See detailMultifactorial Relationship Between 18F-Fluoro-Deoxy-Glucose Positron Emission Tomography Signaling and Biomechanical Properties in Unruptured Aortic Aneurysms
NCHIMI LONGANG, Alain ULg; CHERAMY-BIEN, Jean-Paul ULg; Gasser, T. Christian et al

in Circulation. Cardiovascular imaging (2014), 7

BACKGROUND: -The relationship between biomechanical properties and biological activities in aortic aneurysms was investigated with finite element simulations (FES) and 18F-fluoro-deoxyglucose (18F-FDG ... [more ▼]

BACKGROUND: -The relationship between biomechanical properties and biological activities in aortic aneurysms was investigated with finite element simulations (FES) and 18F-fluoro-deoxyglucose (18F-FDG) positron emission tomography (PET). METHODS AND RESULTS: -The study included 53 patients (45 males) with aortic aneurysms, 47 infrarenal (AAA) and 6 thoracic (TAA), who had at least one 18F-FDG PET/computed tomography. Over a 30-month period, more clinical events occurred in patients with increased 18F-FDG uptake on their last examination than in those without (5/18 (28%) vs. 2/35 (6%); P=0.03). Wall stress and stress/strength index computed by FES and 18F-FDG uptake were evaluating a total of 68 examinations. 25 (38%) examinations demonstrated at least one aneurysm wall area of increased 18F-FDG uptake. The mean number of these areas per examination was 1.6 (18/11) in TAAs vs. 0.25 (14/57) in AAAs, while the mean number of increased uptake areas co-localizing with highest wall stress and stress/strength index areas was 0.55 (6/11) and 0.02 (1/57), respectively. Quantitatively, 18F-FDG PET uptake correlated positively with both wall stress and stress/strength index (P<0.05). 18F-FDG uptake was particularly high in subjects with personal history of angina pectoris and familial aneurysm. CONCLUSIONS: -Increased 18F-FDG PET uptake in aortic aneurysms is strongly related to aneurysm location, wall stress as derived by FES and patient's risk factors such as acquired and inherited susceptibilities. [less ▲]

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See detailMultifocal choroid plexus papilloma: a case report.
Scholsem, Martin; Scholtes, Félix ULg; Robe, Pierre ULg et al

in Clinical neuropathology (2012), 31(6), 430-4

BACKGROUND: Multiple choroid plexus papillomas (CPPs) are rare. Usually, they correspond to villous hypertrophy or metastasis occurring during cerebrospinal dissemination. Multiple CPPs have rarely been ... [more ▼]

BACKGROUND: Multiple choroid plexus papillomas (CPPs) are rare. Usually, they correspond to villous hypertrophy or metastasis occurring during cerebrospinal dissemination. Multiple CPPs have rarely been reported as synchronous tumors. CASE REPORT: Three synchronous CPPs were resected in a 59-year-old female 6 years after their first imaging description. Pathology showed mucus-producing CPP in all 3, 1 of the 3 presenting some signs of atypia. No p53 or hSNF5/INI1 mutation, or signs of polyoma viruses infection were found. CONCLUSION: Although no clear cause for the multifocality was found, the simultaneous presence of the three tumors and their benign histology suggest that they were synchronous and not metastatic. The issue of differentiating synchronous CPPs from metastatic CPP is discussed. [less ▲]

Detailed reference viewed: 41 (5 ULg)
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See detailMultifocal motor and sensory neuropathy following whiplash injury
DIVE, Dominique ULg; NOEZ, Stéphanie ULg; ISERENTANT, Cynthia ULg et al

in Journal of Neurology (2001)

Detailed reference viewed: 44 (5 ULg)
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See detailMultifocal serous cystadenoma of the pancreas synchronous with ampullary adenocarcinoma
Quatresooz, Pascale ULg; Honore, Pierre ULg; Vivario, M. et al

in Annales de Pathologie (2002), 22(4), 317-320

Pancreatic cysts are common, but cystic tumors are uncommon. We report a rare case of serous cystadenoma of the pancreas synchronous with ampullary adenocarcinoma which supports a common etiopathogeny of ... [more ▼]

Pancreatic cysts are common, but cystic tumors are uncommon. We report a rare case of serous cystadenoma of the pancreas synchronous with ampullary adenocarcinoma which supports a common etiopathogeny of these tumors. We discuss the differential diagnosis with mucinous cystadenoma which is potentially malignant and recall the microscopic and radiologic features. [less ▲]

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See detailA multifractal analysis of air temperature signals based on the wavelet leaders method
Deliège, Adrien ULg; Nicolay, Samuel ULg

Conference (2014, August 20)

We present the wavelet leaders method (introduced by S. Jaffard) as a tool to study the Hölder regularity of signals, which is closely related to some functional spaces. We use the associated multifractal ... [more ▼]

We present the wavelet leaders method (introduced by S. Jaffard) as a tool to study the Hölder regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that surface air temperature signals are monofractal, i.e. these are regularly irregular. Then we use this result to establish a climate classification of weather stations in Europe which matches the Köppen-Geiger climate classification. This result could give rise to new criteria to determine the effectiveness of current climatic models. [less ▲]

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See detailMultifractal analysis of air temperature signals using the wavelet leaders method
Deliège, Adrien ULg; Nicolay, Samuel ULg

Conference (2014, May 22)

We use the discrete "wavelet transform microscope" to show that the surface air temperature signals of weather stations selected in Europe are monofractal. This study reveals that the information obtained ... [more ▼]

We use the discrete "wavelet transform microscope" to show that the surface air temperature signals of weather stations selected in Europe are monofractal. This study reveals that the information obtained in this way are richer than previous works studying long range correlations in meteorological stations. The approach presented here allows to bind the Hölder exponents with the climate variability. We also establish that such a link does not exist with methods previously carried out, such as the detrended fluctuation analysis. [less ▲]

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See detailMultifractal analysis of the divergence of wavelet series
Esser, Céline ULg

Conference (2016, June 07)

In this talk, we study pointwise divergence properties of wavelet expansions of functions in a given Besov space. We obtain deterministic upper bounds for the Hausdorff dimensions of the sets of points ... [more ▼]

In this talk, we study pointwise divergence properties of wavelet expansions of functions in a given Besov space. We obtain deterministic upper bounds for the Hausdorff dimensions of the sets of points where a given rate of divergence is observed, and we show that these bounds are generically (in the sense of Baire's categories) optimal. This gives a complement to the works done by F. Bayart and Y. Heurteaux in the case of Fourier series and by J.M. Aubry. [less ▲]

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See detailA multifractal formalism based on the Sν spaces: From theory to practice
Esser, Céline ULg; Kleyntssens, Thomas ULg; Nicolay, Samuel ULg

E-print/Working paper (2014)

We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non ... [more ▼]

We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non-concave spectra, where other multifractal formalisms only lead to the concave hull of the spectra. [less ▲]

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See detailA multifractal formalism for non-concave and non-increasing spectra: the leaders profile method
Esser, Céline ULg; Kleyntssens, Thomas ULg; Nicolay, Samuel ULg

in Applied & Computational Harmonic Analysis (in press)

We present an implementation of a multifractal formalism based on the types of histogram of wavelet leaders. This method yields non-concave spectra and is not limited to their increasing part. We show ... [more ▼]

We present an implementation of a multifractal formalism based on the types of histogram of wavelet leaders. This method yields non-concave spectra and is not limited to their increasing part. We show both from the theoretical and from the applied points of view that this approach is more e cient than the wavelet-based multifractal formalisms previously introduced. [less ▲]

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See detailMultifractal properties of pore-size distribution in apple tissue using X-ray imaging
Mendoza, Fernando; Verboven, Pieter; Ho, Quang Tri et al

in JOURNAL OF FOOD ENGINEERING (2010), 99(2), 206-215

The pore-size distribution (PSD) has an important influence on the complex gas transport phenomena (02 and CO(2)) that occur in apple tissue during storage under controlled atmosphere conditions. It ... [more ▼]

The pore-size distribution (PSD) has an important influence on the complex gas transport phenomena (02 and CO(2)) that occur in apple tissue during storage under controlled atmosphere conditions. It defines the apple tissue microstructure that is correlated to many other apple properties. In this article multifractal analysis (MFA) has been used to study the multiscale structure of the PSD using generalized dimensions in three varieties of apples (Jonagold, Greenstar, and Kanzi) based on X-ray imaging technology (8.5 mu m resolution). Tomographic images of apple samples were taken at two positions within the parenchyma tissue: close to the peel and near to the core. The images showed suitable scaling properties. The generalized dimensions were determined with an R(2) greater than 0.98 in the range of moment orders between -1 and +10. The variation of D(q) with respect to q and the shape of the multifractal generalized spectrum revealed that the PSD structure of apple tissue has properties close to multifractal self-similarity measures. Comparisons among cultivars showed that, in spite of the complexity and variability of the pore space of these apple samples, the extracted generalized dimensions from PSD were significantly different (p < 0.05). The generalized dimensions D(0), D(1), D(2), and the quantity D(0)-D(2) could be used to discriminate tissue samples from different positions or cultivars. Also, high correlations were found between these parameters and the porosity (R(2) >= 0.935). These results demonstrate that MFA is an appropriate tool for characterizing the internal pore-size distribution of apple tissue and thus may be used as a quantitative measure to understand how tissue microstructure affects important physical properties of apple. (C) 2010 Elsevier Ltd. All rights reserved. [less ▲]

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See detailMultifractal wave functions of simple quantum maps
Martin, John ULg; Garcia-Mata, Ignacio; Giraud, Olivier et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2010), 82

We study numerically multifractal properties of two models of one-dimensional quantum maps: a map with pseudointegrable dynamics and intermediate spectral statistics and a map with an Anderson-like ... [more ▼]

We study numerically multifractal properties of two models of one-dimensional quantum maps: a map with pseudointegrable dynamics and intermediate spectral statistics and a map with an Anderson-like transition recently implemented with cold atoms. Using extensive numerical simulations, we compute the multifractal exponents of quantum wave functions and study their properties, with the help of two different numerical methods used for classical multifractal systems (box-counting and wavelet methods). We compare the results of the two methods over a wide range of values. We show that the wave functions of the Anderson map display a multifractal behavior similar to eigenfunctions of the three-dimensional Anderson transition but of a weaker type. Wave functions of the intermediate map share some common properties with eigenfunctions at the Anderson transition (two sets of multifractal exponents, with similar asymptotic behavior), but other properties are markedly different (large linear regime for multifractal exponents even for strong multifractality, different distributions of moments of wave functions, and absence of symmetry of the exponents). Our results thus indicate that the intermediate map presents original properties, different from certain characteristics of the Anderson transition derived from the nonlinear sigma model. We also discuss the importance of finite-size effects. [less ▲]

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See detailA multifractal-based climate analysis
Deliège, Adrien ULg; Nicolay, Samuel ULg

Conference (2014, March 25)

This work consists of a multifractal analysis of surface air temperature in Western and Eastern Europe. The wavelet leaders method enables us to exhibit the monofractal nature of these signals. Then, we ... [more ▼]

This work consists of a multifractal analysis of surface air temperature in Western and Eastern Europe. The wavelet leaders method enables us to exhibit the monofractal nature of these signals. Then, we define a climate classification relying on the Zygmund-Hölder spaces and show that it matches the Köppen classification. By doing so, we evidence the existing relation between the regularity of the temperature data (obtained through functional spaces) and the type of climate. Finally, we give a climatic interpretation of these results. [less ▲]

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See detailMultifractality and intermediate statistics in quantum maps
Martin, John ULg; Giraud, O.; Georgeot, B.

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2008), 77

We study multifractal properties of wave functions for a one-parameter family of quantum maps displaying the whole range of spectral statistics intermediate between integrable and chaotic statistics. We ... [more ▼]

We study multifractal properties of wave functions for a one-parameter family of quantum maps displaying the whole range of spectral statistics intermediate between integrable and chaotic statistics. We perform extensive numerical computations and provide analytical arguments showing that the generalized fractal dimensions are directly related to the parameter of the underlying classical map, and thus to other properties such as spectral statistics. Our results could be relevant for Anderson and quantum Hall transitions, where wave functions also show multifractality. [less ▲]

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See detailMultifractality in quantum maps
Martin, John ULg; Garcia-Mata, Ignacio; Giraud, Olivier et al

Poster (2010, March)

Detailed reference viewed: 11 (4 ULg)
See detailMultifractality in the kicked rotator
Martin, John ULg; Garcia-Mata, Ignacio; Giraud, Olivier et al

Poster (2010, July)

Detailed reference viewed: 37 (9 ULg)
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See detailMultifractality of quantum wave functions
Martin, John ULg; Garcia-Mata, Ignacio; Giraud, Olivier et al

Poster (2013, March 19)

We study the multifractality of individual wave packets in a periodically kicked system through a combination of numerical and analytical works. We consider a version of the mathematical Ruijsenaars ... [more ▼]

We study the multifractality of individual wave packets in a periodically kicked system through a combination of numerical and analytical works. We consider a version of the mathematical Ruijsenaars-Schneider model and reinterpreted it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can be tuned by varying a parameter [1]. We compare different methods to measure the multifractality of wave packets and identify the best one. We find the multifractality to decrease with time until it reaches an asymptotic limit, which is different from the multifractality of eigenvectors but related to it, as is the rate of the decrease. Our results could guide the study of experimental situations where multifractality is present in quantum systems. [less ▲]

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See detailMultifractality of quantum wave functions
Dubertrand, Rémy; Garcia-Mata, Ignacio; Georgeot, Bertrand et al

Poster (2013, September)

Detailed reference viewed: 27 (3 ULg)
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See detailMultifractality of quantum wave functions in the presence of perturbations
Dubertrand, Rémy ULg; Garcia-Mata, Ignacio; Georgeot, Bertrand et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015), 92

We present a comprehensive study of the destruction of quantum multifractality in the presence of perturbations. We study diverse representative models displaying multifractality, including a ... [more ▼]

We present a comprehensive study of the destruction of quantum multifractality in the presence of perturbations. We study diverse representative models displaying multifractality, including a pseudointegrable system, the Anderson model, and a random matrix model. We apply several types of natural perturbations which can be relevant for experimental implementations. We construct an analytical theory for certain cases and perform extensive large-scale numerical simulations in other cases. The data are analyzed through refined methods including double scaling analysis. Our results confirm the recent conjecture that multifractality breaks down following two scenarios. In the first one, multifractality is preserved unchanged below a certain characteristic length which decreases with perturbation strength. In the second one, multifractality is affected at all scales and disappears uniformly for a strong-enough perturbation. Our refined analysis shows that subtle variants of these scenarios can be present in certain cases. This study could guide experimental implementations in order to observe quantum multifractality in real systems. [less ▲]

Detailed reference viewed: 21 (9 ULg)