Neutronic characterization of the MEGAPIE target

The MEGAPIE project aimed to design, build and operate a liquid metal spallation neutron target of about 1 MW beam power in the SINQ facility at the Paul Scherrer Institut (Villigen, Switzerland). This project is an important step in the roadmap towards the demonstration of the accelerator driven system (ADS) concept and high power liquid metal targets in general. Following the design phase, an experimental program was defined to provide a complete characterization of the facility by performing a “mapping” of the neutron flux at different points, from the center of the target to the beam lines. The neutronic performance of the target was studied using different experimental techniques with the goals of validating the Monte Carlo codes used in the design of the target; additionally, the performance was compared with the solid lead targets used before and after the MEGAPIE experiment.     

Development of an improved falling ball viscometer for high-pressure measurements with supercritical CO2

This study presents the development of an improved technique for viscosity measurements under high pressure. The apparatus is based on the principle of the falling ball viscometer, implemented in a high-pressure autoclave fitted with visualisation windows. The originality here is that the balls fall through a tube open at both ends with a diameter slightly greater than that of the balls, allowing a simplified modelling and numerical simulation. A numerical approach has been used for viscosity determination. Calculations have been made with COMSOL Multiphysics^® with the laminar Navier-Stokes model for Newtonian mixtures. It includes the specific hydrodynamic effects without the need for a calibration fluid. However, validation experiments were carried out at atmospheric pressure with dimethylsulfoxide (DMSO) at 298, 308 and 318 K and with cocoa butter at 313 and 353 K, with values of viscosity in the range from 1.4 to 45.4 mPa s. Comparative measurements with literature data have been conducted with cocoa butter saturated with carbon dioxide at 313 and 353 K and for pressures ranging from 0.1 to 25 MPa. At 313 K, viscosity varies from 45.4 mPa s to 3.1 mPa s while at 353 K it varies from 12.4 to 1.9 mPa s. For both isotherms tested, within the range 0-15 MPa, the higher the CO₂ dissolution in the cocoa butter, the lower the viscosity. However, this decrease in viscosity is more pronounced at the lowest temperature. Above 15 MPa the CO₂ dissolution effect on viscosity becomes insignificant, i.e. within the experimental error, due to a counter effect linked with the high hydrostatic pressure. Furthermore, the limits of use of this method have been determined. This technique is revealed as reliable and can therefore be used with other binary systems.     

Illness intrusiveness and quality of life in end-stage renal disease: Comparison and stability across treatment modalities.

Examined the impact of illness intrusiveness (ILI) on quality of life (QOL) in 99 patients with end-stage renal disease. Ss were interviewed twice, 6 wks apart, to determine differences in perceived ILI across treatment modalities, life domains, and time. Life domains were affected differentially across treatments. Perceived ILI correlated significantly with treatment time requirements, uremic symptoms, intercurrent nonrenal illnesses, fatigue, and difficulties in daily activities. Significant QOL differences emerged across treatment modalities for satisfaction/happiness and pessimism/illness related concerns but not for depression/distress. Perceived ILI correlated significantly with each of these QOL measures. Findings substantiate the construct of ILI as a mediator of the psychosocial impact of chronic, life-threatening illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intramuscular injection of hrRANTES causes mast cell recruitment and increased transcription of histidine decarboxylase in mice: lack of effects in genetically mast cell-deficient W/WV mice

RANTES (regulated upon activation, normal T cell expressed and presumably secreted) and other chemoattractant proteins are members of the intercrine or chemokine family of proinflammatory basic polypeptides. RANTES is a prototype of the C-C chemokine subfamily that acts as a selective chemoattractant for human monocytes and CD4-positive lymphocytes and increases the adherence of monocytes to endothelial cells. However, the role of RANTES in white cells is still unclear. We report here that hrRANTES at 20 ng/50 microl in mice causes mast cell recruitment 4 h after intramuscular injection, an effect inhibited by anti-RANTES, as evidenced by 0.1% Toluidine blue, a specific dye for coloring mast cells. Injections of PBS (50 microl) vehicle (negative control) did not produce any appreciable inflammatory response, whereas injection of lipopolysaccharide 20 ng/50 microl (positive control) generated a marked inflammatory state. When RANTES was injected intramuscularly in genetically mast cell-deficient W/Wv mice, the inflammatory effect was not present. The RANTES injection sites were then excised and studied under an optical and electron microscope. A Northern blot analysis was performed using a probe that was prepared to detect mRNA encoding the histidine decarboxylase (HDC) gene on excised muscle tissue. We found that hrRANTES provoked generation of HDC mRNA from muscle tissue after 4 h. These effects were inhibited by an anti-RANTES antibody and were absent in genetically mast cell-deficient mice. The increasing number of mast cells in the RANTES injection sites led to an augmentation of histamine content compared to controls (PBS). The injection of hrRANTES 20 ng/20 microl into the sole of a rat paw confirmed the inflammatory and the mast cell recruitment potential of this chemokine. In these studies, hrRANTES injections in muscle tissue provided direct in vivo evidence that RANTES has a significant effect on mast cell recruitment and HDC mRNA generation.     

The trkA receptor mediates growth cone turning toward a localized source of nerve growth factor

We have developed an in vitro system for studying the interaction of chick dorsal root ganglion neuronal growth cones with a localized source of nerve growth factor (NGF) covalently conjugated to polystyrene beads. Growth cones rapidly turned and migrated under NGF-coated beads in a process that involved the initial formation of persistent contact with a bead, followed by directed flow of cytoplasm toward the point of contact. A role for the local activation of the high-affinity NGF receptor trkA was suggested by a strong inhibition of the turning response by (1) the addition of an antibody against the extracellular portion of trkA, (2) the elevation of the background concentration of NGF to saturate trkA, or (3) the presence of a concentration of the drug K252a that inhibits trkA activation. NGF binding to the pan-neurotrophin receptor p75 is also involved but is not required for turning. These data show a new role for both the trkA and the p75 receptors: the mediation of local events in the guidance of nerve growth cones.     

Localized sources of neurotrophins initiate axon collateral sprouting

The sprouting of axon collateral branches is important in the establishment and refinement of neuronal connections during both development and regeneration. Collateral branches are initiated by the appearance of localized filopodial activity along quiescent axonal shafts. We report here that sensory neuron axonal shafts rapidly sprout filopodia at sites of contact with nerve growth factor-coated polystyrene beads. Some sprouts can extend up to at least 60 micro(m) through multiple bead contacts. Axonal filopodial sprouts often contained microtubules and exhibited a debundling of axonal microtubules at the site of bead-axon contact. Cytochalasin treatment abolished the filopodial sprouting, but not the accumulation of actin filaments at sites of bead-axon contact. The axonal sprouting response is mediated by the trkA receptor and likely acts through a phosphoinositide-3 kinase-dependent pathway, in a manner independent of intracellular Ca2+ fluctuations. These findings implicate neurotrophins as local cues that directly stimulate the formation of collateral axon branches.     

Neutron production in bombardments of thin and thick W, Hg, Pb targets by 0.4, 0.8, 1.2, 1.8 and 2.5 GeV protons

Neutron experimental data relevant to the design of the target of neutron spallation sources are presented and discussed. The data include the reaction cross-sections for W, Hg and Pb investigated with 0.4, 0.8, 1.2, 1.8 and 2.5 GeV proton beams as well as the neutron production, neutron multiplicity distribution, as determined event per event using a high-efficiency detector. The production as a function of target material is investigated for both thin (with a single reaction) and thick targets (multiple reactions). Comparisons are made with the predictions of a high-energy transport code.     

Caregiver-Therapist Ethnic Similarity Predicts Youth Outcomes From an Empirically Based Treatment.

The effects of caregiver-therapist ethnic similarity on youth outcomes from multisystemic therapy (MST), as implemented in dissemination sites, were examined. Consistent with hypotheses, findings confirmed that youths whose caregivers were ethnically matched with their therapists demonstrated greater decreases in symptoms, longer times in treatment, and increased likelihood of discharge for meeting treatment goals relative to youths whose caregivers and therapists were not ethnically matched. In addition, for youths whose caregivers were of mixed ethnic heritage, caregiver-therapist ethnic match was associated with greater improvements in psychosocial functioning. Ethnic match effects on both treatment length and discharge success were partially mediated by therapist adherence to MST. This study shows the importance of examining the effects of both client and therapist ethnicity on outcomes from empirically based treatments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)