Search results for "Diffusion"
showing 10 items of 1615 documents
Association between cingulum bundle structure and cognitive performance: an observational study in major depression.
2009
AbstractBackgroundMajor depression can be regarded as a systemic neurobehavioral disorder resulting from dysfunction of the limbic-cortical networks. The cingulum bundle represents a major association fiber tract of those networks. The aim of our study was to determine the association of brain structural tissue markers of the cingulum bundle and cognitive function in patients with major depression.MethodsRegion-of-interest-based analyses of the middle-anterior and middle-posterior cingulum bundle fractional anisotropy (FA) and mean diffusivity (MD) using color-coded diffusion-tensor imaging and neuropsychological assessment in 14 patients with major depression.ResultsFA of the middle-anteri…
Heteroclinic contours and self-replicated solitary waves in a reaction–diffusion lattice with complex threshold excitation
2008
Abstract The space–time dynamics of the network system modeling collective behavior of electrically coupled nonlinear cells is investigated. The dynamics of a local cell is described by the FitzHugh–Nagumo system with complex threshold excitation. Heteroclinic orbits defining traveling wave front solutions are investigated in a moving frame system. A heteroclinic contour formed by separatrix manifolds of two saddle-foci is found in the phase space. The existence of such structure indicates the appearance of complex wave patterns in the network. Such solutions have been confirmed and analyzed numerically. Complex homoclinic orbits found in the neighborhood of the heteroclinic contour define …
L'introduzione dell'articolo 612-ter del codice penale in materia di diffusione illecita di immagini o video sessualmente espliciti (art. 10, l. 19 l…
2020
Il capitolo affronta l'introduzione del delitto di cui all'art. 612-ter, comunemente noto come "revenge porn".
Multicenter stability of diffusion tensor imaging measures: a European clinical and physical phantom study.
2011
Diffusion tensor imaging (DTI) detects white matter damage in neuro-psychiatric disorders, but data on reliability of DTI measures across more than two scanners are still missing. In this study we assessed multicenter reproducibility of DTI acquisitions based on a physical phantom as well as brain scans across 16 scanners. In addition, we performed DTI scans in a group of 26 patients with clinically probable Alzheimer's disease (AD) and 12 healthy elderly controls at one single center. We determined the variability of fractional anisotropy (FA) measures using manually placed regions of interest as well as automated tract based spatial statistics and deformation based analysis. The coefficie…
Instrument transfer as knowledge transfer in neurophysiology: François Magendie's (1783-1855) early attempts to measure cerebrospinal fluid pressure.
2007
Francois Magendie's (1783-1855) experimental model for measuring blood pressure in animals, which he developed in 1838, had a major impact on French physiology in the nineteenth century, especially upon Etienne-Jules Marey (1830-1904) in Paris. In due course it was also adopted by other European investigators, such as the Leipzig physiologist Carl Ludwig (1816-1895), and by clinicians who developed it into a major measuring tool. Historians of science, however, have paid hardly any attention to Magendie's further laboratory investigations conducted with the assistance of Jean-Louis Marie Poiseuille's (1799-1869) sphygmometre (blood pressure meter). After having used the apparatus to conduct…
Smart Phone, Smart Science: How the Use of Smartphones Can Revolutionize Research in Cognitive Science
2011
WOS:000295936900019; International audience; Investigating human cognitive faculties such as language, attention, and memory most often relies on testing small and homogeneous groups of volunteers coming to research facilities where they are asked to participate in behavioral experiments. We show that this limitation and sampling bias can be overcome by using smartphone technology to collect data in cognitive science experiments from thousands of subjects from all over the world. This mass coordinated use of smartphones creates a novel and powerful scientific "instrument" that yields the data necessary to test universal theories of cognition. This increase in power represents a potential re…
Factors in the global assimilation of collaborative information technologies: an exploratory investigation in five regions
2008
The diffusion of innovation theory is deployed to investigate the global assimilation of collaborative information technologies (CITs). Based on the concepts of IT acquisition and utilization, an assimilation framework is presented to highlight four states (limited, focused, lagging, and pervasive) that capture the assimilation of conferencing and groupware CITs. Data collected from 538 organizations in the United States, Australia, Hong Kong, Norway, and Switzerland are aggregated and analyzed to explore assimilation patterns and the influence of decision-making pattern, functional integration, promotion of collaboration, organization size, and IT function size on the assimilation of CITs.…
Microscopic theory of colloid formation in solids under irradiation
1996
Results of the first-principles study of diffusion-controlled aggregation of Frenkel defects-interstitial atoms-under irradiation of solids are presented. Conditions of the efficient radiation-induced aggregation of vacancies and interstitials are studied and the scenario of this process is presented.
Rotational diffusion of colloid spheres in concentrated suspensions studied by deuteron NMR
1997
We present a study of the application of deuteron-nuclear magnetic resonance spectroscopy (NMR) to the investigation of the rotational diffusion of spherical colloidal particles. We performed NMR pulse experiments on colloidal suspensions of polystyrene latex spheres in water-glycerol mixtures in a wide range of particle volume fractions \ensuremath{\varphi} from the dilute suspension up to \ensuremath{\varphi}=0.504. We have analyzed the stimulated echo NMR signal in the time domain. The full shape of the orientational correlation function deviates from an exponential behavior in the whole \ensuremath{\varphi} range examined. We evaluate the rotational diffusion coefficient and calculate i…
The effect of the internal architecture of polymer micronetwork colloids on the dynamics in highly concentrated dispersions
2007
Motivated by the finding that colloidal dispersions of polymer micronetwork spheres with a cross-link density of 1:50 (inverse number of monomer units between crosslinks) show significant deviations from the dynamics of hard spheres in the colloid glass as seen by dynamic light scattering (DLS) (E. Bartsch, V. Frenz, H. Sillescu J. Non — Cryst. Solids 172–174 (1994), 88–97), we have undertaken a systematic study of the effect of the crosslink density on the dynamics at high concentrations. Long-time self-diffusion coefficients D S L and collective diffusion coefficients D c were measured for colloids with crosslink densities of 1:10, 1:20 and 1:50 by forced Rayleigh scattering (FRS) and the…