Transient beam loading effects in harmonic rf systems for light sources

Harmonic cavities have been used in storage rings to lengthen bunches and increase beam lifetimes dominated by Touschek scattering. Transient beam loading in the harmonic cavities generated by asymmetries in the fill pattern causes significant variation of the bunch synchronous phase and bunch length along the bunch train when the longitudinal restoring force has been reduced. This results in a significant reduction in the mean bunch lengthening and potential lifetime increase. We describe how beam current modulations give rise to transient effects much larger than expected from the linear model of the beam cavity interaction. We also develop a tracking simulation to predict results and apply this simulation to an analysis of the beam loading transients for the case of passive and active normal and superconducting third harmonic rf systems using Advanced Light Source parameters

Télédétection des pollutions par hydrocarbures de l'"AMOCO CADIZ"

At first, the chronology of remote sensing flights organized by CNEXO, IFP and IGN is summarized. Secondly, examples of the most commonly observed phenomena along the coastline are presented. An interpretation of the various data collected is given for the area of Roscoff, taken as a model. This interpretation is extended to draw a serie of maps of sea and coastline pollution for several days between March 18 to May 26, 1978. The maps for the 18th and 21st of March are enclosed.Une présentation est faite de la chronologie des interventions de télédétection réalisées par le CNEXO, l'IFP et l'IGN et des moyens mis en oeuvre. Quelques phénomènes couramment observés le long de la côte sont dé­taillés. A partir de l'exemple type de la zone de Roscoff, on présente l'in­terprétation, réalisée à l'aide des différents enregistrements. Cette méthode a été généralisée afin d'obtenir une cartographie de la pollution de la mer et des côtes à différentes dates, entre le 18 mars et le 26 mai 1978. Deux des cartes ainsi réalisées, pour les journées du 18 et du 21 mars 1978, sont fournies en annexe

Performance evaluation of the IRIS XL-220 PET/CT system, a new camera dedicated to non-human primates

Background: Non-human primates (NHP) are critical in biomedical research to better understand the pathophysiology of diseases and develop new therapies. Based on its translational and longitudinal abilities along with its non-invasiveness, PET/CT systems dedicated to non-human primates can play an important role for future discoveries in medical research. The aim of this study was to evaluate the performance of a new PET/CT system dedicated to NHP imaging, the IRIS XL-220 developed by Inviscan SAS. This was performed based on the National Electrical Manufacturers Association (NEMA) NU 4-2008 standard recommendations (NEMA) to characterize the spatial resolution, the scatter fraction, the sensitivity, the count rate, and the image quality of the system. Besides, the system was evaluated in real conditions with two NHP with 18F-FDG and (-)-[18F]FEOBV which targets the vesicular acetylcholine transporter, and one rat using 18F-FDG. Results: The full width at half maximum obtained with the 3D OSEM algorithm ranged between 0.89 and 2.11 mm in the field of view. Maximum sensitivity in the 400–620 keV and 250–750 keV energy windows were 2.37% (22 cps/kBq) and 2.81% (25 cps/kBq), respectively. The maximum noise equivalent count rate (NEC) for a rat phantom was 82 kcps at 75 MBq and 88 kcps at 75 MBq for energy window of 250–750 and 400–620 keV, respectively. For the monkey phantom, the maximum NEC was 18 kcps at 126 MBq and 19 kcps at 126 MBq for energy window of 250–750 and 400–620 keV, respectively. The IRIS XL provided an excellent quality of images in non-human primates and rats using 18F-FDG. The images acquired using (-)-[18F]FEOBV were consistent with those previously reported in non-human primates. Conclusions: Taken together, these results showed that the IRIS XL-220 is a high-resolution system well suited for PET/CT imaging in non-human primates

Induction of cholestasis in the perfused rat liver by 2-aminoethyl diphenylborate, an inhibitor of the hepatocyte plasma membrane Ca2+ channels

Journal compilation © 2004 Blackwell Publishing Asia Pty Ltd and Journal of Gastroenterology and Hepatology FoundationBackground and Aims: An increase in the cytoplasmic free Ca2+ concentration in hepatocytes as a result of the release of Ca2+ from intracellular stores and Ca2+ inflow from the extracellular space is a necessary part of the mechanism by which bile acids are moved along the bile cannaliculus by contraction of the cannaliculus. 2-Aminoethyl diphenylborate (2-APB) is a recently discovered inhibitor of store-operated plasma membrane Ca2+ channels in hepatocytes. The aim of the present study was to test the ability of 2-APB to inhibit bile flow. Methods: Bile flow was measured in the isolated perfused rat liver using cannulation of the common bile duct. Measurements were carried out in the presence or absence of 2-APB in either the presence of taurocholic acid (to enhance basal bile flow) or in the absence of taurocholic acid and in the presence of the hormones vasopressin and glucagon, which are known to stimulate bile flow. Results: In livers perfused in the presence of taurocholic acid, 2-APB reversibly inhibited bile flow with a slow time of onset. The time of onset of inhibition was reduced by prior addition of the endoplasmic reticulum (Ca2+ + Mg2+)adenosine triphosphatase inhibitor, 2,5-di-t-butylhydroquinone. In livers perfused in the absence of taurocholate, 2-APB had little effect on the basal rate of bile flow, but inhibited the ability of vasopressin and glucagon to stimulate bile flow. Conclusions: It is concluded that an inhibitor of hepatocyte plasma membrane Ca2+ channels can induce cholestasis. The results provide evidence that suggests that, over a period of time, the normal function of hepatocyte store-operated Ca2+ channels is required to maintain bile flow. Future strategies directed at the regulation of bile flow might include pharmacological or other interventions that modulate Ca2+ inflow to hepatocytesRoland B. Gregory, Rachael Huges and Gregory J Barrit