Search results for " Walker"
showing 10 items of 10 documents
Cartographie de la pollution lumineuse zénithale en Bourgogne à partir de données de population et d'occupation du sol
2007
L'étude a pour but de fournir une première cartographie très simple de la pollution lumineuse sous SIG afin de faciliter l'interprétation géographique et, par la suite, la mise en relation avec d'autres facteurs. Bien sûr, un passage vers un modèle prédictif devient nécessaire si l'outil se destine à être une aide décisionnelle ou un outil de recherche ayant pour but d'analyser les conséquences des changements de certains de ses paramètres. Ainsi, un tel modèle pourra servir à évaluer et analyser les conséquences de la pollution lumineuse générée par la construction d'un nouveau quartier résidentiel, d'une zone indus‐ trielle, de nouvelles infrastructures routières.
Congenital muscular dystrophy: from muscle to brain.
2016
Congenital muscular dystrophies (CMDs) are a wide group of muscular disorders that manifest with very early onset of muscular weakness, sometime associated to severe brain involvement. The histologic pattern of muscle anomalies is typical of dystrophic lesions but quite variable depending on the different stages and on the severity of the disorder. Recent classification of CMDs have been reported most of which based on the combination of clinical, biochemical, molecular and genetic findings, but genotype/phenotype correlation are in constant progression due to more diffuse utilization of the molecular analysis. In this article, the Authors report on CMDs belonging to the group of dystroglyc…
A fully automatic approach for multimodal PET and MR image segmentation in gamma knife treatment planning
2017
The aim of this study is to combine Biological Target Volume (BTV) segmentation and Gross Target Volume (GTV) segmentation in stereotactic neurosurgery.Our goal is to enhance Clinical Target Volume (CTV) definition, including metabolic and morphologic information, for treatment planning and patient follow-up.We propose a fully automatic approach for multimodal PET and MR image segmentation. This method is based on the Random Walker (RW) and Fuzzy C-Means clustering (FCM) algorithms. A total of 19 brain metastatic tumors, undergone stereotactic neuro-radiosurgery, were retrospectively analyzed. A framework for the evaluation of multimodal PET/MRI segmentation is presented, considering volume…
Stochastic reconstruction of sandstones
2000
A simulated annealing algorithm is employed to generate a stochastic model for a Berea and a Fontainebleau sandstone with prescribed two-point probability function, lineal path function, and ``pore size'' distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparison of simple morphological quantities indicates good agreement between the reconstructions and the original sandstones. Also, the mean survival time of a random walker in the pore space is reproduced with good accuracy. However, a more detailed investigation by means of local porosity theory shows that there may be s…
Optimal Resource Discovery Paths of Gnutella2
2008
This paper shows that the performance of peer-to-peer resource discovery algorithms is upper bounded by a k-Steiner minimum tree and proposes an algorithm locating near-optimal query paths for the peer-to-peer resource discovery problem. Global knowledge of the topology and the resources from the peer-to-peer network are required as an input to the algorithm. The algorithm provides an objective measure for defining how good local search algorithms are. The performance is evaluated in simulated peer-to-peer scenarios and in the measured Gnutella2 P2P network topology with four local search algorithms: breadth-first search, self-avoiding random walker, highest degree search and Dynamic Query …
Using anatomic and metabolic imaging in stereotactic radio neuro-surgery treatments
2016
Diffusive thermal dynamics for the spin-S Ising ferromagnet
2008
We introduce an alternative thermal diffusive dynamics for the spin-S Ising ferromagnet realized by means of a random walker. The latter hops across the sites of the lattice and flips the relevant spins according to a probability depending on both the local magnetic arrangement and the temperature. The random walker, intended to model a diffusing excitation, interacts with the lattice so that it is biased towards those sites where it can achieve an energy gain. In order to adapt our algorithm to systems made up of arbitrary spins, some non trivial generalizations are implied. In particular, we will apply the new dynamics to two-dimensional spin-1/2 and spin-1 systems analyzing their relaxat…
From Random Walker to Vehicular Traffic: Motion on a Circle
2014
Driving of cars on a highway is a complex process which can be described by deterministic and stochastic forces. It leads to equations of motion with asymmetric interaction and dissipation as well as to new energy flow law already presented at previous TRAFFIC AND GRANULAR FLOW meetings. Here we consider a model, where motion of an asymmetric random walker on a ring with periodic boundary conditions takes place. It is related to driven systems with active particles, energy input and depot. This simple model can be further developed towards more complicated ones, describing vehicular or pedestrian traffic. Three particular cases are considered, starting with discrete coordinate and time, the…
HPMA-LMA copolymer drug carriers in oncology: an in vivo PET study to assess the tumor line-specific polymer uptake and body distribution.
2013
Polymeric drug carriers aim to selectively target tumors in combination with protecting normal tissue. In this regard polymer structure and molecular weight are key factors considering organ distribution and tumor accumulation of the polymeric drug delivery system. Four different HPMA based copolymer structures (random as well as block copolymers with lauryl methacrylate as hydrophobic block) varying in molecular weight, size and resulting architecture were analyzed in two different tumor models (AT1 prostate carcinoma and Walker-256 mammary carcinoma) in vivo. Polymers were labeled with (18)F and organ/tumor uptake was followed by μPET imaging and ex vivo biodistribution. Vascular permeabi…
Il ritorno alla fotografia: cultura visuale dall’analogico al digitale
2018
La fotografia ha svolto un ruolo fondamentale per l’affermazione e la definizione della cultura visuale: nei primi anni del Novecento essa ha posto le basi per il suo sviluppo; oggi che quella prospettiva sembra essere in crisi per l’avvento del digitale è utile ritornare a quegli anni per comprendere il presente. Accanto alle riflessioni di Walter Benjamin e László Moholy-Nagy, è stata fondamentale l’attività di Franz Roh, che trova un esaustivo compimento teorico nel breve testo foto-auge (1929): al di là delle felici intuizioni e delle feconde proposte che emergono in questo scritto, è degno di nota che esso diventa l’esempio privilegiato cui far riferimento anche dall’altra sponda dell’…