Hanbury-Brown-Twiss measurements at large rapidity separations, or can we measure the proton radius in p-A collisions?

We point out that current calculations of inclusive two-particle correlations in p-A collisions based on the Color Glass Condensate approach exhibit a contribution from Hanbury-Brown-Twiss correlations. These HBT correlations are quite distinct from the standard ones, in that they are apparent for particles widely separated in rapidity. The transverse size of the emitter which is reflected in these correlations is the gluonic size of the proton. This raises an interesting possibility of measuring the proton size directly by the HBT effect of particle pairs produced in p-A collisions.Comment: 11 pages, 3 eps figures; v2: comments, discussions, references and acknowledgements added, conclusions unchanged, final versio

Next-to-eikonal corrections in the CGC: gluon production and spin asymmetries in pA collisions

We present a new method to systematically include corrections to the eikonal approximation in the background field formalism. Specifically, we calculate the subleading, power-suppressed corrections due to the finite width of the target or the finite energy of the projectile. Such power-suppressed corrections involve Wilson lines decorated by gradients of the background field - thus related to the density - of the target. The method is of generic applicability. As a first example, we study single inclusive gluon production in pA collisions, and various related spin asymmetries, beyond the eikonal accuracy.Comment: 34 pages, new reference added, some typos correcte

Universality of traveling waves with QCD running coupling

``Geometric scaling'', i.e. the dependence of DIS cross-sections on the ratio Q/Q_S, where Q_S(Y) is the rapidity-dependent \saturation scale, can be theoretically obtained from universal ``traveling wave'' solutions of the nonlinear Balitsky-Kovchegov (BK) QCD evolution equation at fixed coupling. We examine the similar mean-field predictions beyond leading-logarithmic order, including running QCD coupling.Comment: 4 pages, 3 figures,, Invited talk given at the DIS 2007 Conference, Munich, Germany, April 2007; Change of titl

Simultaneous two-channel MR imaging, single voxel spectroscopy and chemical shift imaging by reconfiguration of a 'standard' Biospec spectrometer

International audienceSimultaneous two channel array proton imaging, single voxel PRESS and CSI acquisitions were demonstrated after reconfiguration and minimum hardware modification of a standard 4.7T BioSpec® spectrometer. Validation of the reconfiguration was assessed in phantoms and in a mouse brain. The modified configuration used the X channel exhibiting similar SNR performances compared to the 1H channel. The SNR gain for the two channel array coil was up to 1.3 compared to the SNR obtained with a reference surface coil. Compared to regular two element coil with quadrature combination, the SNR was improved with an additional gain of 1.3. These modifications could also be applied for any X nucleu

Shock wave collisions in AdS5: approximate numerical solutions

We numerically study the evolution of a boost-invariant N=4 SYM medium using AdS/CFT. We consider a toy model for the collision of gravitational shock waves, finding that the energy density first increases, reaches a maximum and then starts to decrease, matching hydrodynamics for late times. For the initial conditions we consider, the hydrodynamic scale governing the late time behaviour is to very good approximation determined by the area of the black hole horizon at initial times. Our results provide a toy model for the early time evolution of the bulk system in heavy-ion collisions at RHIC and the LHC.Comment: 29 pages, 9 figure

Active optical decoupling circuit for radio frequency endoluminal coil

International audienceDespite the enhanced image provided by multiple-channels array coils, an accurate exploration of bowel diseases and detailed information about the gastrointestinal wall layers are still not available. The use of endoluminal RF coil located in the region of interest could potentially allow good evaluation of tumor invasion or depth of inflammatory processes [1]. However, since metallic coaxial cables are used, patient safety is threatened due to local electric field concentration that can happen and the associated local high Specific Absorption Rate (SAR) [2]. Moreover, in this case, cable isolation and traps cannot be straightforwardly employed due to limited dimension. Signal transmission based onoptical fiber is an alternative to coaxial cables to solve definitively the electromagnetic issues. On a receiver coil, both signal transmission and decoupling have to be insured. For MR signal transmission, the electro-optical conversion has been partially validated based on electro-optic effect of some crystals [3]. In this work, an active optical decoupling circuit for endoluminal coil is presented and compared to a reference coil with regular decoupling using bias signal though coaxial cable

Evaluation of bio-integration of rat knee cartilage repair using in vivo MRI at 7T

National audienceHigh-field magnetic resonance systems allowing high-resolution magnetic resosnance imaging -HR-MRI) is a powerful research tool to visualize and examine hyaline cartilage of small joints non-invasively. Different studies have shown that qualitative assessment of degenerative joint disease, derived from MR images, was reliable. The capability to show pathologic changes throughout the time course of the disease from three-dimensional (3D) datasets has also been demonstrated. However, in vivo quantitative imaging for an accurate determination of cartilage thickness and volume is challenging due to small size of rodent joints and dedicated coils are mandatory. Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation or matrix associated autologous cell transplantation require non invasive technique to evaluate longitudinally the biointegration of the graft. The aim of this study was to follow using 7T MRI the biointegration of biomaterials colonized by mesenchymal stem cells or not after implantation in a calibrated full thickness focal lesion in the rat knee

Design of a four-channel array coil for dual high-resolution rat knee MR Imaging

International audienc

Fouling and Cleaning of Modified Stainless Steel Plate Heat Exchangers Processing Milk Products

Fouling of heat exchangers in dairy industries is still quite a severe problem both technically and economically. Altering the surface properties of the heating surfaces would be a way of solving this issue. Modified steel surfaces were tested in an Alfa Laval V2 plate heat exchanger throughout dairy product sterilization. The behavior was analyzed for 8 different surface treatments, such as coatings (Diamond Like Carbon [DLC], Silica, SiOX, Ni-P-PTFE, Excalibur®, Xylan®) and ion implantation (SiF+, MoS2). All fouling and cleaning experiments were carried out in standard and well-controlled operating conditions. After fouling, no significant difference could be seen between all the modified steels and the reference by statistical variance analysis. Cleaning efficiency of Ni-PPTFE appeared significantly the best. It could be suggested that the free surface energy plays a predominant role and the roughness a minor role in the level of fouling and cleaning efficiency