210 research outputs found
Glucose transformations over a mechanical mixture of ZnO and Ru/C catalysts: Product distribution, thermodynamics and kinetics
No full textTransformations of glucose to 1,2-propylene glycol were studied over a mechanical mixture of ZnO and Ru/C catalysts in the presence of hydrogen. Different reaction conditions were evaluated by changing the reaction temperature and hydrogen pressure. In addition to the cascade mode of operation, also separate steps in the overall reaction network, such as hydrogenation of pyruvaldehyde and hydroxyacetone to 1,2-propylene glycol were investigated. Fructose as a starting material was also studied resulting in a propylene glycol yield of 37.5%. The optimal temperature for glucose transformation to propylene glycol was found to be 165 °C. The influence of temperature on the catalytic behavior was more prominent than the effect of hydrogen pressure. Thermodynamic analysis of glucose transformation to 1,2-propylene glycol was performed and a plausible kinetic model reflecting a complex reaction network was developed being able to describe the data in a reliable way
Complete set of polarization observables in (pol)p(pol)p->pp pi0 clos to threshold
No full textIn a kinematically complete experiment we have measured the two analyzing powers and the five spin correlation coefficients of the reaction (pol)p pol(p) -> p p pi0 as a function of all five parameters of the three-body final state for bombarding energies</p
Complete set of polarization observables in (pol)p(pol)p->pp pi0 clos to threshold
No full textIn a kinematically complete experiment we have measured the two analyzing powers and the five spin correlation coefficients of the reaction (pol)p pol(p) -> p p pi0 as a function of all five parameters of the three-body final state for bombarding energies</p
Spin correlations in polarized p polarized p -> p n pi+ production near threshold
No full textA first measurement of longitudinell as well as transverse spin correlation coefficients for the reaction pp->pn pi+ is made using a polarized proton target and a polarized proton beam. We report kinematically complete measurements for this reaction at 32</p
Quantitative analysis of cardiac left ventricular variables obtained by MRI at 3 T : a pre- and post-contrast comparison
No full textShort-axis cine images are acquired during cardiac MRI in order to determine variables of cardiac left ventricular (LV) function such as ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and LV mass. In cardiac perfusion assessments this imaging can be performed in the temporal window between first pass perfusion and the acquisition of delayed enhancement images in order to minimise overall scanning time. The objective of this study was to compare pre- and post-contrast short-axis LV variables of 15 healthy volunteers using a two-dimensional cardiac-gated segmented cine true fast imaging with steady state precession sequence and a 3.0 T MRI unit in order to determine the possible effects of contrast agent on the calculated cardiac function variables. Image analysis was carried out using semi-automated software. The calculated mean LV mass was lower when derived from the post-contrast images, relative to those derived pre-contrast (102 vs 108.1 g, p<0.0001). Small but systematic significant differences were also found between the mean pre- and post-contrast values of EF (69.4% vs 68.7%, p<0.05), EDV (142.4 vs 143.7 ml, p<0.05) and ESV (44.2 vs 45.5 ml, p<0.005), but no significant differences in SV were identified. This study has highlighted that contrast agent delivery can influence the numerical outcome of cardiac variables calculated from MRI and this was particularly noticeable for LV mass. This may have important implications for the correct interpretation of patient data in clinical studies where post-contrast images are used to calculate LV variables, since LV normal ranges have been traditionally derived from pre-contrast data sets.Peer reviewe
The pp -> d pi(+)pi(0) reaction – a case of Delta Delta excitation without ABC effect
No full textThe ABC effect, a low-mass enhancement in the invariant ππ mass, is observed in double-pionic fusion reactions leading to a bound nuclear system in the final state. From previous measurements there have been indications that this phenomenon is resctricted to the σ channel of the ππ system. With exclusive measurements of the pp → dπ<sup>+</sup>π<sup>0</sup> reaction at T<sub>p</sub> = 1.1 GeV we demonstrate that, indeed, the ABC effect does not occur in the vector-isovector ππ channel (ρ channel) despite the fact that the ΔΔ excitation is oberved to be the dominant reaction process. We also show that this reaction is well described by a t-channel ΔΔ excitation with the subsequent decay into the vector-isovector ππ channel given by the ρ channel operator</p
D5.1.1 Models of Real-time Applications on Service Oriented Infrastructures
No full textThe IRMOS project is developing tools and techniques for modelling, simulating, analysing, and planning real-time applications on service oriented infrastructures. These tools and techniques support the processes involved in designing, developing, deploying and executing applications where guaranteed QoS is needed. The report considers the value-chain for real-time applications hosted by third-party service providers. In the context of this value chain, we analyse who might benefit from the use of models, how and why these models might be used, and when during the application lifecycle modelling is most useful. Techniques are presented for building models of real-time applications including the use of stochastic process algebras, finite state automata, workflow models (e.g. BPEL, BPMN and YAWL) and specification languages (e.g. UML MARTE). The report discusses how these models need to be supported by estimation of application resource consumption, e.g. through benchmarking and fitting, and how mapping techniques allow models to be built for different actors in the value chain, e.g. for application providers and infrastructure providers. Tool support is also discussed e.g. PRISM for probabilistic model checking and Visual Service Composition Studio for service-oriented modelling. A detailed and specific real-time application scenario is included and modelled to allow the various techniques presented in this document to be demonstrated and quantitatively evaluated. The scenario also reveals the level of detail needed in order for meaningful modelling to be achieved in practice. The modelling scenario has been carefully engineered to be as representative as possible of the broad range of application characteristics encountered in the three reference IRMOS applications (film postproduction, eLearning, virtual and augmented reality). The modelling techniques discussed and then demonstrated in this report include identifying what resources are necessary to support an application, when those resources will be required during the application workflow, what performance is needed from them (i.e. QoS) and what will happen to the application if the required performance is not delivered. All of these are essential when developing and then agreeing service level agreements between the various entities in a service oriented infrastructure
Study of the p+d -> He-3+2 pi reaction at Celsius
No full textThe exclusive p + d -->(3) He + 2 pi reaction has been studied at CELSIUS at a beam energy of 477 MeV. Preliminary results indicate that the two pions are created mainly in an isospin T = 1 state.</p
- …
