Application of spherical harmonics derived space rotation invariant indices to the analysis of multiple sclerosis lesions' geometry by MRI

In the longitudinal study of multiple sclerosis (MS) lesions, varying position of the patient inside the MRI scanner is one of the major sources of assessment errors. We propose to use analytical indices that are invariant to spatial orientation to describe the lesions, rather than focus on patient repositioning or image realignment. Studies were made on simulated lesions systematically rotated, from in vitro MS lesions scanned on different days, and from in vivo MS lesions from a patient that was scanned five times the same day with short intervals of time between scans. Each of the lesions' 3D surfaces was approximated using spherical harmonics, from which indices that are invariant to space rotation were derived. From these indices, an accurate and highly reproducible volume estimate can be derived, which is superior to the common approach of 2D slice stacking. The results indicate that the suggested approach is useful in reducing part of the errors that affect the analysis of changes of MS lesions during follow-up studies. In conclusion, our proposed method circumvents the need for precise patient repositioning and can be advantageous in MRI longitudinal studies of MS patients.     

Evaluation of micro-bubble size and gas hold-up in two-phase gas-liquid columns via scattered light measurements

In this paper, potential use of an elliptically polarized light scattering (EPLS) method to monitor both bubble size and gas hold-up in a bubble-laden medium is explored. It is shown that with the use of the new EPLS system, normalized scattering matrix elements (M_ij's) measured at different side and back-scattering angles can be used to obtain the desired correlations between the bubble sizes and input flow parameters for a gas-liquid (GL) column, including gas flow rate and surfactant concentrations. The bubble size distributions were first evaluated experimentally using a digital image processing system for different gas flows and surfactant concentrations. These images showed that the bubbles were not necessarily spherical. We investigated the possibility of modeling the bubbles as effective spheres. The scattering matrix elements were calculated using the Lorenz-Mie theory and the results were compared against the experimentally determined values. It was observed that the change in the bubble size yields significant changes in M₁₁, M₃₃, M₄₄, and M₃₄ profiles. An optimum single measurement angle of θ=120^° was determined for a gas velocity range of 0.04-0.35 cm/s (). The choice of the optimum angle depends on frit pore size, column diameter, gas pressure, and surfactant concentration. These results suggest that a simplified version of the present EPLS system can effectively be used as a two-phase flow sensor to monitor bubble size and liquid hold-up in industrial systems.     

Loss tolerance in one-way quantum computation via counterfactual error correction

We introduce a scheme for fault tolerantly dealing with losses (or other "leakage" errors) in cluster state computation that can tolerate up to 50% qubit loss. This is achieved passively using an adaptive strategy of measurement--no coherent measurements or coherent correction is required. Since the scheme relies on inferring information about what would have been the outcome of a measurement had one been able to carry it out, we call this counterfactual error correction.     

Drag reduction in bubbly Taylor-Couette turbulence

In Taylor-Couette flow the total energy dissipation rate and therefore the drag can be determined by measuring the torque on the system. We do so for Reynolds numbers between Re=7 x 10(4) and Re=10(6) after having injected (i) small bubbles (R=1 mm) up to a volume concentration of alpha=5% and (ii) buoyant particles (rhop/rhol=0.14) of comparable volume concentration. In case (i) we observe a crossover from little drag reduction at smaller Re to strong drag reduction up to 20% at Re=10(6). In case (ii) we observe at most little drag reduction throughout. Several theoretical models for bubbly drag reduction are discussed in view of our findings.     

Molecular structural analysis of 55mol% CuI-45mol% Ag2MoO4 solid electrolyte using XPS and laser raman techniques

The solid electrolyte 55 mol% CuI - 45 mol% Ag₂MoO₄ has been analyzed structurally by employing X-ray photoelectron spectroscopic (XPS) and laser Raman studies. The core level Ag 3d, Cu 2p, Mo 3d, I 3d and O1s XPS spectra of the constituent elements were recorded. The presence of both bridging (BO) and non-bridging (NBO) oxygen atoms in the oxyanion framework has been identified through the deconvolution of the O 1s spectrum. Laser Raman spectroscopic studies tend to reveal that the oxyanion framework is constructed with [MoO ₄ ²⁻ ]-tetrahedral and [MoO₆]-octahedral units as in the case of CuI - Cu₂MoO₄ and AgI - Ag₂O - MoO₃ glasses.     

The kinetics of muon-catalyzed dt fusion

A main source of information about the muon-catalyzed fusion cycle in D-T mixtures are the cycling rates _c, which are characteristic for the kinetic equilibrium of states attained rapidly in dense targets. The measurement, analysis and interpretation of these rates will be discussed, concentrating on the extensive set of rates observed at PSI over the last decade in gaseous, liquid and solid targets.Invited talk presented by Peter Kammel.     

Survey of experimental results on μCF including hyperfine effects

Complementary to the investigations of the most efficient dt cycle, also the other muon-induced fusion cycles in mixtures of hydrogen isotopes have been studied. The results of these dedicated experiments provide rich information about muon-induced few-body reactions and contribute significantly to a better overall understanding of CF. A summary of the recent progress will be presented. Special emphasis will be put on two characteristic examples, namely a new experimental approach to study the muonic cascade in H-D mixtures and the systematic study of hyperfine effects in muon-induced reactions.