Search results for "methods [Diffusion Tensor Imaging]"
showing 10 items of 992 documents
Villes, densité et fractalité
1995
International audience; Ce bref article résumé les résultats d'analyses fractales effectuées sur les villes françaises à plusieurs dates pour deux niveaux d'observation: les tissus urbains caractérisés par la distribution spatiale des surfaces bâties d'une part, et le semis des villes de différentes tailles dans l'ensemble du territoire français d'autre part. Les méthodes de mesure sont rapidement expliquées, l'accent est mis sur la signification des nombres obtenus, leur comparaison d'une ville à l'autre et leur évolution au cours du temps.
Nonlinear Time-Series Adaptation for Land Cover Classification
2017
Automatic land cover classification from satellite image time series is of paramount relevance to assess vegetation and crop status, with important implications in agriculture, biofuels, and food. However, due to the high cost and human resources needed to characterize and classify land cover through field campaigns, a recurrent limiting factor is the lack of available labeled data. On top of this, the biophysical–geophysical variables exhibit particular temporal structures that need to be exploited. Land cover classification based on image time series is very complex because of the data manifold distortions through time. We propose the use of the kernel manifold alignment (KEMA) method for…
Search for magnetically-induced signatures in the arrival directions of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory
2020
We search for signals of magnetically-induced effects in the arrival directions of ultra-high-energy cosmic rays detected at the Pierre Auger Observatory. We apply two different methods. One is a search for sets of events that show a correlation between their arrival direction and the inverse of their energy, which would be expected if they come from the same point-like source, they have the same electric charge and their deflection is relatively small and coherent. We refer to these sets of events as "multiplets". The second method, called "thrust", is a principal axis analysis aimed to detect the elongated patterns in a region of interest. We study the sensitivity of both methods using a …
Les inégalités environnementales en Bourgogne
2016
L'évolution de l'occupation humaine : l'analyse spatiale exploratoire des données.Le problème de l'incertitude et de l'hétérogénéité des données en a…
2011
The analysis of the evolution of the settlement requires a lot of methodological questioning. Despite a frequent use of the spatial analysis methods, few works return to their methodological problems. This article proposes to make a comparison and a discussion around two exploratory statistical methods (the K function of Ripley and the Kernel Density Estimation). It seems that scale, quality and quantity of input data, are three essential parameters to be taken into account so as to lead a spatial analysis in archaeology. In intrinsic way, archaeological data are non homogeneous. For that purpose, our article proposes a multi scalar approach integrating the non homogeneousness character of …
Offensive Transitions in High-Performance Football: Differences Between UEFA Euro 2008 and UEFA Euro 2016
2019
[Abstract] Coaches, footballers and researchers agree that offensive transitions are one of the most important moments in football today. In a sport where defense over attack dominates, with low scores on the scoreboard, the importance of these actions from the offensive point of view becomes very important. Despite this, scientific literature is still very limited on this topic. Therefore, the objectives set out in the present investigation have been two: first, by means of a proportion analysis and the application of a chisquare test, it was intended to describe the possible differences between the offensive transitions made in the UEFA Euro 2008 and UEFA Euro 2016; then, through differen…
Pinpointing the SMBH in NGC1052
2016
Supermassive black holes (SMBH) are essential for the production of jets in radio-loud active galactic nuclei (AGN). Theoretical models based on Blandford & Znajek (1977MNRAS.179..433B) extract the rotational energy from a Kerr black hole, which could be the case for NGC1052, to launch these jets. This requires magnetic fields on the order of 1000G to 10000G. We imaged the vicinity of the SMBH of the AGN NGC1052 with the Global Millimetre VLBI Array and found a bright and compact central feature that is smaller than 1.9 light days (100 Schwarzschild radii) in radius. Interpreting this as a blend of the unresolved jet bases, we derive the magnetic field at 1 Schwarzschild radius to lie betwe…
Sub-milliarcsecond imaging of 3C111
2020
Flares in radio-loud active galactic nuclei (AGNs) are thought to be associated with the injection of fresh plasma into the compact jet base. Such flares are usually strongest and appear earlier at shorter radio wavelengths. Hence, very long baseline interferometry (VLBI) at millimeter (mm)-wavelengths is the best-suited technique for studying the earliest structural changes of compact jets associated with emission flares. Aims. We study the morphological changes of the parsec-scale jet in the nearby (z=0.049) gamma-ray bright radio galaxy 3C 111 following a flare that developed into a major radio outburst in 2007. We analyse three successive observations of 3C 111 at 86 GHz with the Global…
22GHz image of 3C 273
2017
RadioAstron is a 10m orbiting radio telescope mounted on the Spektr-R satellite, launched in 2011, performing Space Very Long Baseline Interferometry (SVLBI) observations supported by a global ground array of radio telescopes. With an apogee of ~350000km, it is offering for the first time the possibility to perform as-resolution imaging in the cm-band. The RadioAstron Active Galactic Nuclei (AGN) polarization Key Science Project (KSP) aims at exploiting the unprecedented angular resolution provided by RadioAstron to study jet launching/collimation and magnetic-field configuration in AGN jets. The targets of our KSP are some of the most powerful blazars in the sky. We present observations at…
New sample of large angular size radio galaxies. I.
2001
We present a new sample of 84 large angular size radio galaxies selected from the NRAO VLA Sky Survey. Radio sources with declination above +60{deg}, total flux density greater than 100mJy at 1.4GHz and angular size larger than 4' have been selected and observed with the VLA at 1.4 and 4.9GHz. The radio observations attempt to confirm the large angular size sources and to isolate the core emission for optical identification. In this paper, the first of a series of three, we present radio maps of 79 sources from the sample and discuss the effects of the selection criteria in the final sample. 37 radio galaxies belong to the class of giants, of which 22 are reported in this paper for the firs…