Relativistic approach to electromagnetic imaging

A novel imaging principle based on the interaction of electromagnetic waves with a beam of relativistic electrons is proposed. Wave-particle interaction is assumed to take place in a small spatial domain, so that each electron is only briefly accelerated by the incident field. In the one-dimensional case the spatial distribution of the source density can be directly observed in the temporal spectrum of the scattered field. Whereas, in the two-dimensional case the relation between the source and the spectrum is shown to be approximately the Radon transform.Comment: 10 pages, 1 figur

Lyon (9e) – Vaise, Chais Beaucairois, 26-28 rue Joannès-Carret

Les fouilles conduites de janvier à avril 2006 sur le site des Chais Beaucairois ont révélé une histoire plus riche que ne le laissait supposer le diagnostic. Les différents vestiges découverts traduisent une occupation du site depuis l’époque néolithique jusqu’à l’époque moderne (fig. 1 et 2). Les vestiges découverts se rattachent à cinq grandes périodes (six avec les vestiges des bâtiments industriels du xixe s.). Fig. 1 – Vue générale de la fouille Cliché : équipe de fouille. Fig. 2 – Vue..

Compensation de déformations en tomographie dynamique 3D conique

19 pagesIn dynamic tomography, the measured object or organs are no-longer supposed to be static in the scanner during the acquisition but are supposed to move or to be deformed. Our approach is the analytic deformation compensation during the reconstruction. Our work concentrates on 3D cone beam tomography. We introduce a new large class of deformations preserving the 3D cone beam geometry. We show that deformations from this class can be analytically compensated. We present numerical experiments on phantoms showing the compensation of these deformations in 3D cone beam tomography

Compensation of some time dependent deformations in tomography.

This work concerns 2D + t dynamic tomography. We show that a much larger class of deformations than the affine transforms can be compensated analytically within filtered back projection algorithms in 2D parallel beam and fan beam dynamic tomography. We present numerical experiments on the Shepp and Logan phantom showing that nonaffine deformations can be compensated. A generalization to 3D cone beam tomography is proposed

Les foyers culinaires du « sanctuaire de Cybèle » et la question des cuisines à <i>Lugdunum</i>

International audienceThe excavations conducted between 1991 and 2003 at the place of the so-called "sanctuaire de Cybèle" brought to light an Augustan house with a kitchen which had a masonry cooking platform. Another cooking place with two hearths was also found in a room adjacent to the praetorium cryptoporticus. It is not the first time in Lyon that such equipments were uncovered. Two masonry cooking devices have been brought to light during the construction in 1972 of the museum in Fourvière, in the same room. This kind of equipment, which can be compared to Italic cases, looks like a feature of Romanization. This type of stove is not the only example of cooking structures discovered at Lyon and other ones have been uncovered, notably rue des Farges. Other kinds of hearths have also been excavated in dwellings, among which some probably had a double function: cooking and heating.Les fouilles, réalisées entre 1991 et 2003 à l’emplacement du prétendu « sanctuaire de Cybèle », ont permis la mise au jour d’une maison augustéenne dont la cuisine comportait une table de cuisson maçonnée. Un autre bloc-cuisine équipé de deux foyers a été également dégagé dans une pièce attenante au cryptoportique du prétoire. Ce n’est pas la première fois que de tels aménagements sont découverts à Lyon. Lors de la construction du musée de Fourvière en 1972, deux blocs-cuisine maçonnés ont été mis au jour dans la même pièce. Ce type d’aménagements comparables à des exemples italiques semble un caractère de romanisation. Ces « cuisinières » ne sont pas les seules structures culinaires découvertes à Lyon et d’autres exemples ont été mis au jour, rue des Farges notamment. D’autres types de foyers ont été également dégagés dans des habitats, avec pour certains une fonction sans doute mixte : la cuisine et le chauffage

La datation de l'aqueduc du Gier, à Lyon : état d’une question controversée

La construction de l’aqueduc du Gier, le plus important des aqueducs lyonnais, a d’abord été attribuée à l’empereur Claude en se fondant sur la découverte au XVIIIe siècle, à Fourvière, de tuyaux de plomb marqués de son nom. À la suite de la mise au jour, en 1887, de la « pierre de Chagnon » affichant un édit de l’empereur Hadrien concernant la protection de l’aqueduc, l’hypothèse d’une construction sous Hadrien a prévalu, jusqu’à ce que la découverte sur le site du Verbe Incarné, en 1982, d’une fontaine au nom de Claude, ne remette au goût du jour une datation claudienne. Celle-ci a été à son tour remise en cause par la mise en évidence d’adductions d’eau sur le plateau de Fourvière, dès l’époque d’Auguste, à une altitude que seul pouvait atteindre l’aqueduc du Gier. L’attribution à Claude ou à Hadrien ayant encore des partisans, il a semblé souhaitable de reprendre tous les éléments du dossier.Attribution of the construction of Gier aqueduct, the largest aqueduct in the Lyon region, was first made to Claudius on the basis of the discovery in Fourvière in the 18th century of lead pipes bearing his name. Following the unearthing in 1887 of the "pierre de Chagnon", which bears an edict from Hadrian relating to the protection of the aqueduct, opinion regarding attribution of the monument to Hadrian prevailed until the discovery in 1982 on the site of the Verbe Incarné of a fountain built on behalf of Claudius that shifted favour back again. However, this has also been called into question by water conveyances excavated on Fourvière plateau dating from the Augustan era at an altitude that could only connect with the aqueduct at Gier. Attribution to Claudius and Hadrian still having their supporters, it seemed desirable to gather all the elements pertaining to the subject together.Der Bau des Aquädukts von Gier, des bedeutendsten der Aquädukte von Lyon, wurde zunächst Kaiser Claudius zugeschrieben, wobei man sich auf die im 18. Jh. in Fourvière entdeckten Bleirohrinschriften auf seinen Namen stützte. Infolge der Entdeckung des „pierre de Chagnon“ im Jahr 1887, auf dem ein Edikt des Kaisers Hadrian zum Schutz des Aquädukts zu lesen war, setzte sich die Hypothese des Baus unter Hadrian durch bis 1982 auf dem Fundplatz Verbe Incarné ein Brunnen entdeckt wurde, der eine Inschrift auf den Namen des Kaisers Claudius trug und erneut die claudische Datierung zur Diskussion brachte. Diese Datierung wurde wiederum durch die Freilegung von augusteischen Wasserzuleitungen auf dem Plateau von Fourvière infrage gestellt, da diese Höhe nur das Aquädukt von Gier erreichen konnte. Da die Zuweisung zu Claudius oder Hadrian noch ihre Befürworter hat, schien es sinnvoll, alle Elemente dieser Problematik wiederaufzunehmen

Behavior of a GPI-anchored protein in phospholipid monolayers at the air–water interface

AbstractThe interaction between alkaline phosphatase (AP), a glycosylphosphatidylinositol (GPI)-anchored protein (AP-GPI), and phospholipids was monitored using Langmuir isotherms and PM-IRRAS spectroscopy. AP-GPI was injected under C16 phospholipid monolayers with either a neutral polar head (1,2-dipalmitoyl-sn-glycero-3-phosphocholine monohydrate (DPPC)) or an anionic polar head (1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine (DPPS)). The increase in molecular area due to the injection of protein depended on the surface pressure and the type of phospholipid. At all surface pressures, it was highest in the case of DPPS monolayers. The surface elasticity coefficient E, determined from the π–A diagrams, allowed to deduct that the AP-GPI–phospholipid mixtures presented a molecular arrangement less condensed than the corresponding pure phospholipid films. PM-IRRAS spectra suggested different protein–lipid interactions as a function of the nature of the lipids. AP-GPI modified the organization of the DPPS deuterated chains whereas AP-GPI affected only the polar group of DPPC at low surface pressure (8 mN/m). Different protein hydration layers between the DPPC and DPPS monolayers were suggested to explain these results. PM-IRRAS spectra of AP-GPI in the presence of lipids showed a shape similar to those collected for pure AP-GPI, indicating a similar orientation of AP-GPI in the presence or absence of phospholipids, where the active sites of the enzyme are turned outside of the membrane

Determination of molecular groups involved in the interaction of annexin A5 with lipid membrane models at the air–water interface

AbstractAnnexin A5 (AnxA5) is a member of a family of homologous proteins sharing the ability to bind to negatively charged phospholipid membranes in a Ca2+-dependent manner. In this paper, we used polarization-modulated infrared reflection absorption spectroscopy (PMIRRAS), Brewster angle microscopy (BAM), and ellipsometry to investigate changes both in the structure of AnxA5 and phospholipid head groups associated with membrane binding. We found that the secondary structure of AnxA5 in the AnxA5/Ca2+/lipid ternary complex is conserved, mainly in α-helices and the average orientation of the α-helices of the protein is slightly tilted with respect to the normal to the phospholipid monolayer. Upon interaction between AnxA5 and phospholipids, a shift of the νas PO2− band is observed by PMIRRAS. This reveals that the phosphate group is the main group involved in the binding of AnxA5 to phospholipids via Ca2+ ions, even when some carboxylate groups are accessible (PS). PMIRRAS spectra also indicate a change of carboxylate orientation in the aspartate and glutamate residues implicated in the association of the AnxA5, which could be linked to the 2D crystallization of protein under the phospholipid monolayer. Finally, we demonstrated that the interaction of AnxA5 with pure carboxylate groups of an oleic acid monolayer is possible, but the orientation of the protein under the lipid is completely different

SPECT/CT registration with the DCC and MC simulations for SPECT imaging

publi Vincent Breto