Search results for " Computer Science"
showing 10 items of 3983 documents
Superficial Siderosis of the Central Nervous System associated with Hemophilia A: A case report
2021
Abstract Superficial Siderosis of the Central Nervous System (SSCNS) is a condition secondary to the deposition of hemosiderin within the subpial layers of central nervous system leading to its progressive degeneration, clinically responsible for hearing impairment, cerebellar ataxia and pyramidal syndrome. Here we report the case of a 61-year-old man with medical history of congenital hemophilia A presenting with typical clinical features of SSCNS associated with extensive hypo-intensity on fast 2D gradient-echo-weighted sequences, along the spinal cord, posterior fossa's structures and cerebral cortex. Interestingly, although his disorder was revealed by a lumbar spinal stenosis, presurgi…
A Fuzzy-based Clinical Decision Support System for coeliac disease
2022
Coeliac disease (CD) is a permanent inflammatory disease of the small intestine characterized by the destruction of the mucous membrane of this intestinal tract. Coeliac disease represents the most frequent food intolerance and affects about 1% of the population, but it is severely underdiagnosed. Currently available guidelines require CD-specific serology and atrophic histology in duodenal biopsy samples to diagnose CD in adults. In paediatric CD, but recently in adults also, non-invasive diagnostic strategies have become increasingly popular. In order to increase the rates of correct diagnosis of the disease without the use of biopsy, researchers have recently been using approaches based …
OMNI-DRL: Learning to Fly in Forests with Omnidirectional Images
2022
Perception is crucial for drone obstacle avoidance in complex, static, and unstructured outdoor environments. However, most navigation solutions based on Deep Reinforcement Learning (DRL) use limited Field-Of-View (FOV) images as input. In this paper, we demonstrate that omnidirectional images improve these methods. Thus, we provide a comparative benchmark of several visual modalities for navigation: ground truth depth, ground truth semantic segmentation, and RGB images. These exhaustive comparisons reveal that it is superior to use an omnidirectional camera to navigate with classical DRL methods. Finally, we show in two different virtual forest environments that adapting the convolution to…
Contributions to the physical and experimental validation of a simultaneous PET/MRI system dedicated to small animal imaging
2020
Simultaneous PET/MRI is a dynamic research field of both medical and preclinical domains. The ability of integrated systems to acquire the highly complementarity MR morphological and PET functional data in a single examination paves the way to innovative applications. The hereby document presents a series of experimentations dealing with the performance evaluation and the experimental in vivo capacities of such a device. Physical measurements were implemented based on international standards or inspired by articles of reference. The evaluated system consists of a compact SiPM-based PET subsystem fully integrated in a 7 T preclinical MRI based on the dry magnet technology. Experimentations s…
Periodicity, morphisms, and matrices
2003
In 1965, Fine and Wilf proved the following theorem: if (fn)n≥0 and (gn)n≥0 are periodic sequences of real numbers, of period lengths h and k, respectively, and fn = gn for 0 ≤ n > h + k - gcd(h,k), then fn = gn for all n ≥ 0. Furthermore, the constant h + k - gcd(h,k) is best possible. In this paper, we consider some variations on this theorem. In particular, we study the case where fn ≤ gn, instead of fn = gn. We also obtain generalizations to more than two periods.We apply our methods to a previously unsolved conjecture on iterated morphisms, the decreasing length conjecture: if h : Σ* → Σ* is a morphism with |Σ|= n, and w is a word with |w| < |h(w)| < |h2(w)| < ... < |hk(w)|, then k ≤ n.
A multidimensional critical factorization theorem
2005
AbstractThe Critical Factorization Theorem is one of the principal results in combinatorics on words. It relates local periodicities of a word to its global periodicity. In this paper we give a multidimensional extension of it. More precisely, we give a new proof of the Critical Factorization Theorem, but in a weak form, where the weakness is due to the fact that we loose the tightness of the local repetition order. In exchange, we gain the possibility of extending our proof to the multidimensional case. Indeed, this new proof makes use of the Theorem of Fine and Wilf, that has several classical generalizations to the multidimensional case.
Quantitative prediction of effective material properties of heterogeneous media
1999
Effective electrical conductivity and electrical permittivity of water-saturated natural sandstones are evaluated on the basis of local porosity theory (LPT). In contrast to earlier methods, which characterize the underlying microstructure only through the volume fraction, LPT incorporates geometric information about the stochastic microstructure in terms of local porosity distribution and local percolation probabilities. We compare the prediction of LPT and of traditional effective medium theory with the exact results. The exact results for the conductivity and permittivity are obtained by solving the microscopic mixed boundary value problem for the Maxwell equations in the quasistatic app…
Introduction to molecular topology: basic concepts and application to drug design.
2012
In this review it is dealt the use of molecular topology (MT) in the selection and design of new drugs. After an introduction of the actual methods used for drug design, the basic concepts of MT are defined, including examples of calculation of topological indices, which are numerical descriptors of molecular structures. The goal is making this calculation familiar to the potential students and allowing a straightforward comprehension of the topic. Finally, the achievements obtained in this field are detailed, so that the reader can figure out the great interest of this approach.
High-repetition-rate source delivering optical pulse trains with a controllable level of amplitude and temporal jitters
2020
International audience; We theoretically propose and numerically validate an all-optical scheme to generate optical pulse trains with varying peak-powers and durations. A shaping of the spectral phase thanks to discrete /2 phase shifts enables an efficient phase-to-intensity conversion of a temporal phase modulation based on a two-tone sinusoidal beating. Experiments carried out at telecommunication wavelengths and at a repetition rate of 10 GHz confirm the ability of our approach to efficiently generate a train made of pulses with properties that vary from pulse-to-pulse. The levels of jitters can be accurately controlled.
Effect of electron correlation corrections on phase competition in Ag film on MgO substrate
2002
Abstract The effect of electron correlation corrections in the novel theory predicting the growth mode of a thin metallic film on an insulating substrate has been studied. We discuss the influence of the substrate slab thickness on the energies of formation for several two-dimensional phases, which, in principle, may form in Ag layer on (0 0 1) MgO substrate. We analyze also the sensitivity of the key energy parameter––Fourier transform of the mixing potential V (0) to the choice of correlation functionals.