3,700 research outputs found
Etude de la fonction cardiaque 4D à partir de ciné cardiaque 3D via une synchronisation sur la respiration et rythme cardiaque: travail de Bachelor
Objectifs : Dans le cadre de lâexploration cardiaque en IRM, nous expĂ©rimentons une sĂ©quence 4D Ă partir dâune sĂ©quence 4D Flow. Lâobjectif est de calculer la fraction dâĂ©jection et de la comparer avec la sĂ©quence 2D cinĂ© (gold standard actuel) utilisĂ©e cliniquement. GrĂące Ă des outils statistiques, nous Ă©valuons la reproductibilitĂ© intra- et inter-opĂ©rateurs de la sĂ©quence 4D. Nous regardons Ă©galement la prĂ©cision de cette sĂ©quence en comparant les rĂ©sultats des segmentations 4D aux segmentations de la sĂ©quence 2D cinĂ©. MĂ©thodologie : Dans un premier temps, nous avons optimisĂ© la sĂ©quence 4D en modifiant certains paramĂštres comme la vitesse dâencodage retenue Ă 30cm/s et le tracking factor (tf) de 0.6 Ă mouvement mesurĂ© (au niveau du diaphragme). Les sĂ©quences ont Ă©tĂ© rĂ©alisĂ©es, Ă quatre temps diffĂ©rents, sur trois individus sains. Dans un second temps, nous avons calculĂ© la fraction dâĂ©jection du ventricule gauche (FEVG) en le segmentant en diastole et en systole selon la mĂ©thode Simpson. Cela a Ă©tĂ© fait sur la sĂ©quence 4D et sur la 2D cinĂ©, deux fois, afin dâobtenir des donnĂ©es plus consĂ©quentes pour mesurer la corrĂ©lation entre les deux techniques et la variabilitĂ© entre chaque opĂ©rateur. Enfin, chaque valeur obtenue est introduite dans un tableau Excel, puis convertie sous forme dâĂ©quation ICC et Bland-Altman. A partir de ça, nous calculons la variabilitĂ© intra- et inter-opĂ©rateur, ce qui nous permet de visualiser la concordance de nos rĂ©sultats et de comparer les valeurs obtenues pour le 4D avec celles obtenues pour le 2D cinĂ©. RĂ©sultats : Les calculs ICC donnent des valeurs entre 0.71 et 0.96 pour les diffĂ©rents temps d'acquisitions. Ces donnĂ©es traduisent de bonnes corrĂ©lation et reproductibilitĂ© intra-opĂ©rateur, par rapport Ă ce que dit la littĂ©rature (> 0.75). Quant Ă la variabilitĂ© inter-opĂ©rateur, elle est, dans l'ensemble, en dessous de la valeur de rĂ©fĂ©rence (< 0.4) synonyme d'une faible corrĂ©lation entre opĂ©rateur. Suite Ă ces rĂ©sultats peu encourageants, nous voulions trouver la source dâerreur. En Ă©tudiant les volumes systoliques et diastoliques sĂ©parĂ©ment (et non la FEVG), nous constatons un rĂ©sultat Ă©levĂ© en diastole (0.78), mais en dessous de nos moyennes en systole (0.4). Conclusion : Suite Ă l'analyse de nos rĂ©sultats, nous constatons que le travail de segmentation de chacun d'entre nous subit une amĂ©lioration avec le temps et nous permet de diminuer la variabilitĂ© entre 2D cinĂ© et 4D. La reproductibilitĂ© est observĂ©e en intra- mais est Ă rĂ©Ă©valuer de façon plus approfondie en inter-opĂ©rateur
Quantification of the temporal change of diffusion patterns following mild traumatic brain injury
Quantifying the timecourse of recovery from mild traumatic brain injury using diffusion tensor imaging
normal and anomalous suppressions in a hadron and string cascade model
A mechanism for the effective dissociation of a pair in the colour
electric field of strings is introduced into a hadron and string cascade model,
i.e. JPCIAE, which is based on the LUND model, simulating ultra-relativistic
nucleus - nucleus collisions. This new mechanism together with the known
mechanism of nuclear absorption (both baryons and mesons) could reproduce
fairly the data of the normal and anomalous suppressions in minimum
bias pA, AB (with light projectile), and Pb + Pb collisions at 200 A GeV/c.
However the impact parameter (E_T) dependence of the suppression
factor, both, in S + U and Pb + Pb reactions at 200 A GeV/c and 158 A GeV/c,
respectively, is not well reproduced. We also tested the additional mechanism
of the energy degradation of leading particles, with which both, the normal and
anomalous suppressions in minimum bias pA, AB, and Pb + Pb collisions
and the E_T dependence of the suppression factor are better
reproduced.Comment: 16 pages (RevTex), 6 ps-figures, to be published in J. Phys.
HIV activates indoleamine 2,3-dioxygenease: inhibition of T cell proliferation by tryptophan starvation
Organoids to evaluate novel treatment strategies for intrahepatic cholestatic disease
Abstract category: 17. Peroxisomal, sterol, bile acid, lipid and lipoprotei
Gyrate atrophy of the choroid and retina with hyper-ornithinemia responsive to vitamin B6: a case report
<p>Abstract</p> <p>Background</p> <p>Gyrate atrophy of the retina and choroid is a rare autosomal recessive inherited disease, characterized by progressive chorioretinal atrophy that results in progressive deterioration of peripheral and night vision and leading to blindness.</p> <p>Case presentation</p> <p>This report presents a case of a 28-year-old man consulting for a progressive fall of visual acuity with hemeralopia. Eye fundoscopy showed regions of confluent rounded chorioretinal atrophy. The visual field and retinal angiography were altered. A high level of plasma ornithine (629 nmol/mL) was detected and a diagnosis of gyrate atrophy of the retina and choroid was made. The patient was treated with high dose Pyridoxine supplement (300 mg/d for 6 months) and the ornithine level of his serum was successfully reduced.</p> <p>Conclusion</p> <p>The exact mechanism of chorioretinal atrophy in hyper-ornithinemia is not known and a small percentage of the affected people respond to Vitamin B6 supplementation.</p
Interference of urinary bile acid profiling by propofol
Abstract category: 02. Novel diagnostic/laboratory methods / 17. Peroxisomal, sterol, bile acid, lipid and lipoprotei
Mid-infrared plasmons in scaled graphene nanostructures
Plasmonics takes advantage of the collective response of electrons to
electromagnetic waves, enabling dramatic scaling of optical devices beyond the
diffraction limit. Here, we demonstrate the mid-infrared (4 to 15 microns)
plasmons in deeply scaled graphene nanostructures down to 50 nm, more than 100
times smaller than the on-resonance light wavelength in free space. We reveal,
for the first time, the crucial damping channels of graphene plasmons via its
intrinsic optical phonons and scattering from the edges. A plasmon lifetime of
20 femto-seconds and smaller is observed, when damping through the emission of
an optical phonon is allowed. Furthermore, the surface polar phonons in SiO2
substrate underneath the graphene nanostructures lead to a significantly
modified plasmon dispersion and damping, in contrast to a non-polar
diamond-like-carbon (DLC) substrate. Much reduced damping is realized when the
plasmon resonance frequencies are close to the polar phonon frequencies. Our
study paves the way for applications of graphene in plasmonic waveguides,
modulators and detectors in an unprecedentedly broad wavelength range from
sub-terahertz to mid-infrared.Comment: submitte
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