M. Cogneau

A Direct Measurement of the F-18(p,Alpha)o-15 Reaction

The cross section for the F-18(p,alpha) O-15 reaction has been obtained in reverse kinematics (F-18 beam on CH2 target) between 550 and 740 keV above threshold, i.e. in a region of astrophysical interest. The reaction yield is dominated by a wide resonant state whose spin, parity, total width and partial widths were deduced from the analysis of the alpha-particle and elastic proton data.

Experimental determination of the 7Be+p scattering lengths

The Be-7 + p elastic cross section has been measured at the Centre de Recherches du Cyclotron RIB facility at Louvain-la-Neuve in the c.m. energy region from 0.3 to 0.75 MeV by bombarding a proton-rich target with a radioactive 7Be beam. The recoil protons have been detected in the angular range theta(c.m.) = 120.2degrees-131.1degrees and theta(c.m.) = 156.6degrees-170.2degrees using the LEDA system. From a R-matrix analysis of the cross section data. we obtain the energy and the width of the I resonance (E-X = 0.77 MeV). The iota = 0 scattering lengths a(01) = 25 +/- 9 fm (channel spin I = 1) and a(02) = -7 +/- 3 fm (channel spin I = 2) have been deduced. They are compared to values expected from charge-symmetry properties. Implications on the low energy S-factor of the Be-7(p,gamma)B-8 reaction are discussed

Regional brain glucose utilization in adenylosuccinase-deficient patients measured by positron emission tomography.

ABSTRACT: Regional brain glucose utilization was investigated by positron emission tomography with fluorodeox-yglucose in three children with adenylosuccinase deficiency. A consistent pattern was found in the three patients, namely a marked decrease of fluorodeoxyglucose uptake in all gray structures, with the exception of the cerebellum, which was minimally affected. Anomalies predominated in the cerebral cortex, particularly in the anterior regions; they were less pronounced in thalamus and basal ganglia. The observations suggest that positron emission tomography may be a useful tool for the localization of the deleterious effects of metabolic diseases and for the investigation of their pathophysiologic mechanisms.

Assessment of thallium-201 redistribution versus glucose uptake as predictors of viability after coronary occlusion and reperfusion.

Both 201Tl redistribution and persistent glucose uptake have been proposed as markers of viability after reperfusion. In the present study, they have been compared in the same open-chest canine preparation of occlusion and reperfusion. Ten fasting dogs were subjected to 2 hr of left anterior descending coronary artery occlusion and 4 hr of reperfusion. Myocardial blood flow was determined by a microsphere technique 100 min after occlusion and 3 hr after reperfusion. 201Tl was injected intravenously 20 min before reperfusion. Serial biopsy samples were obtained from ischemic and normal areas. 18F-2-deoxyglucose, a tracer of exogenous glucose uptake, was injected 3 hr after reperfusion. Thirty minutes before the animals were killed, simultaneous blood samples were taken from the femoral artery and the regional coronary veins draining the reperfused and the remote areas. Dogs were killed 4 hr after reperfusion was established. Area at risk was assessed by dye injection in vivo and area of necrosis by triphenyl tetrazolium chloride (TTC) staining, with confirmation by electron microscopy. Immediately after death, endocardial and epicardial samples were taken from regions characterized as risk regions, areas of necrosis, areas of patchy necrosis, and normal areas. These samples were counted in a scintillation well counter. Four hours after reperfusion, in ischemic myocardium (TTC positive) the relative 201Tl gradient between ischemic and normal regions was 26 +/- 13%, whereas in necrotic samples, this gradient was 71 +/- 26%.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of aluminium on calcium and magnesium uptake and translocation by root segments of whole seedlings of Norway spruce (Picea abies Karst.)

In the Ardennes, spruce decline is correlated with Mg deficiency caused by acid rain leaching of soil nutrients, associated with solubilization of Al-containing soil minerals. Laboratory experiments were carried out to measure the uptake and translocation of 45Ca and 28 Mg by intact roots of spruce seedlings in solutions containing various amounts of added AlCl3. Translocation rates in the various organs of the seedlings were higher for magnesium than for calcium. A 1 mt M Al nutrient solution had a much stronger inhibitory effect on uptake and translocation of Mg than it had on Ca. These rate differences result largely from differences in the chemical characteristics of these two elements.

Measurement of cerebral blood flow with a bolus of oxygen-15-labelled water: Comparison of dynamic and integral methods

A method is presented for the measurement of cerebral blood flow (CBF) with a bolus of water labelled with oxygen 15. The method, which has been evaluated in normal volunteers, is based on Ketys model, with two additional parameters to account for the difference in the time of tracer arrival in the radial and carotid arteries (“delay”) and for dispersion of the tracer in the body and/or blood counting systems. It combines the advantages of: (i) dynamic data collection for estimation of delay and dispersion; (ii) robustness and linearity of CBF estimates with an integral method; and (iii) simplicity of continuous external monitoring of arterial blood radioactivity, particularly with repeated measurements. An optimized protocol is proposed for routine applications in neurological and neurophysiological studies.

Absolute cross sections and excitation functions for deuteron-induced reactions on the nickel isotopes between 2 and 12 MeV☆

Abstract Absolute cross sections and excitation functions for the reactions 58 Ni(d, n) 59 Cu, 61 Ni (d, n) 62 Cu, 62 Ni(d, 2n) 62 Cu, 60 Ni(d, n) 61 Cu and 58 Ni(d, t) 57 Ni have been measured by activation using the stacked-foil technique. The (d,n) experimental excitation functions are compared to the theoretical calculations of F. Perey based on a non-local, optical-model potential.

The production of radioisotopes for medical applications by the adiabatic resonance crossing (ARC) technique

The Transmutation by Adiabatic Resonance Crossing (TARC) technique has been proposed by Rubbia (Resonance enhanced neutron captures for element activation and waste transmutation, CERN-LHC/97-0040EET, 1997; TARC collaboration, Neutron-driven nuclear transmutation by adiabatic resonance crossing, CERN-SL-99-036EET, 1999; Abanades et al., Nucl. Instr. and Meth. A 487 (2002) 577) for element activation and waste transmutation. We investigate the possibility to use this technique for the industrial production of Mo-99 and Xe-125 by resonance neutron capture in Mo-98 and Xe-124, respectively. Their daughters, i.e. Tc-99m and I-125, are widely used in medical applications. The high neutron flux needed is produced by bombarding a thick Be target with 65 or 75 MeV proton beam (few microamperes). This target is placed at the centre of a large cubic lead assembly (1.6m side, purity: 99.999%). The neutrons are progressively slowed down by elastic scattering on lead, and their energies scan the region where neutron resonances occur (in the eV range). Samples are properly located in the lead assembly where the resonance neutron capture probability is maximised. This paper presents the very promising results obtained by activation of metallic Mo-nat foils and Xe-nat. The results obtained on Au, In and W samples are also presented. These samples have been used to calculate the neutron fluence at various positions in the lead assembly

The 18F(p,α) reaction and its astrophysical implications

F-18 radioactive beams were used to measure the F-18(p,alpha) reaction in the c.m. energy ranges of 265-535 keV and 550-740 keV. In each case, a resonant level was clearly detected, of which the resonant strength and some other properties were deduced. The astrophysical reaction rate was calculated down to the novae peak temperature. Consequences for the hot CNO cycles were drawn

Quantitative Assessment of Erythropoiesis in Bone-marrow Expansion Areas Using Fe-52

Summary. Quantitative 52Fe scans were performed in 180 patients. Expansion of bone marrow was observed in 70. This bone marrow expansion was a nearly constant feature in haemolytic anaemia and in sideroblastic anaemia. It occurred in a third of the patients with myelofibrosis. In patients with polycythaemia rubra vera, expansion was noticed in only two out of seven. Erythropoiesis in expansion areas occurred despite persistence of fat in the iliac crest bone marrow biopsy. It could exist with a slight increase in erythropoiesis and might develop only after a long period of erythropoietic stimulation.Increased marrow activity can take place without erythropoietic expansion in long bones. The fraction of iron uptake in expansion areas did not exceed a third of total marrow iron uptake. With increasing erythropoiesis, the increase in iron uptake in expansion areas was less marked than the increase in the central areas. Erythropoiesis in expansion areas was usually not of major quantitative importance but could nevertheless reach the erythropoiesis of a normal adult.