Analysis of wave patterns in MR elastography of skeletal muscle using coupled harmonic oscillator simulations

The ability to study muscle elasticity in vivo would be of great clinical interest. Magnetic resonance elastography (MRE) has the potential to quantify noninvasively the distribution of the shear modulus in muscle tissue. Elasticity information may be derived by extracting frequencies from the wave patterns of phase-contrast MRE images. In a new approach, MRE wave patterns were reconstructed using 3D coupled harmonic oscillator calculations (CHO). To analyze in vivo MRE measurements of the biceps brachii of healthy volunteers, different anisotropic fibrous structures for the couplings between the muscle elements have to be assumed. V-shaped wave patterns as observed when excitation was applied on the tendon were reproduced by a model, where in a central band of stiff fascicles wave propagation was about twice as fast as that in surrounding tissue. Planar waves were observed for excitation near the muscle surface. They could be reconstructed by assuming a simultaneous wave excitation of all muscle fibers, where fibers along the main muscle axis were coupled more strongly than those perpendicular to the axis. The results show that CHO calculations provide a fast and reliable method for incorporating anatomical information of the investigated tissue in the reconstruction of complex wave patterns.     

The energy dependence of the 4d photoionization cross-section of In and Sb

The energy dependence of 4d partial photoionization cross-section for In and Sb has been determined experimentally using the photoemission technique. It exhibits a pronounced Cooper minima and compares favorably with the one-electron Hartree Fock calculation for atomic Xe by Kennedy and Manson.     

Co chemisorption on PtCu surfaces III. CO on PtCu(111)

Selected thermal desorption and valence band photoemission data on the chemisorption of CO on PtCu(111) surfaces are presented. The main objective is to make a comparison with CO chemisorption on an annealed (1 × 3) reconstructed Pt_0.98Cu_0.02(110) surface. The (111) alloy surfaces are unreconstructed (1 × 1) surfaces, with average near-surface Cu concentrations ranging from ? 7.5% to ? 20% as indicated by the Cu 920 eV Auger signal. It is observed that the effect of alloying Pt(111) with Cu is to progressively lower the desorption peak temperature and hence the free energy of CO desorption from Pt sites. A second observation is that the energy distribution of the Cu 3d-derived states is little affected by CO adsorption on Cu sites at 155 K. Both these results offer a contrast to the results for CO/Pt_0.98Cu_0.02(110) reported earlier.     

Similarity solutions in unsteady boundary layer theory in magneto-fluid dynamics

Zusammenfassung Es werden Ähnlichkeitslösungen der instationären Grenzschichtgleichung unter Berücksichtigung von Magnetfeldern untersucht. Das äussere Magnetfeld wurde als senkrecht zur Hauptströmung und die elektrische Leitfähigkeit wurde als klein angenommen. Da das Magnetfeld sich mit Raum und Zeit ändern kann, erhält man eine Reihe neuer Ähnlichkeitslösungen. Im wesentlichen kann man fünf Fälle unterscheiden. Teilweise ist es möglich, ein konstantes Magnetfeld zuzulassen.     

Transformation of hex-2-enopyranosyl trichloroacetimidates - a correction

Contrary to previous results hex-2-enopyranosyl trichloroacetimidates do not rearrange to amino-branched glycals but give N-acylated hex-2-enopyranosyl amines.     

High-Flux Carbon Molecular Sieve Membranes for Gas Separation

Carbon membranes have great potential for highly selective and cost-efficient gas separation. Carbon is chemically stable and it is relative cheap. The controlled carbonization of a polymer coating on a porous ceramic support provides a 3D carbon material with molecular sieving permeation performance. The carbonization of the polymer blend gives turbostratic carbon domains of randomly stacked together sp² hybridized carbon sheets as well as sp³ hybridized amorphous carbon. In the evaluation of the carbon molecular sieve membrane, hydrogen could be separated from propane with a selectivity of 10 000 with a hydrogen permeance of 5 m³(STP)/(m²hbar). Furthermore, by a post-synthesis oxidative treatment, the permeation fluxes are increased by widening the pores, and the molecular sieve carbon membrane is transformed from a molecular sieve carbon into a selective surface flow carbon membrane with adsorption controlled performance and becomes selective for carbon dioxide.     

Laser-accelerated protons with energy-dependent beam direction

The spatial distribution of protons, accelerated by intense femtosecond laser pulses interacting with thin target foils under oblique irradiation are investigated. Under certain conditions, the proton beams are directed away from the target normal. This deviation is towards the laser forward direction, with an angle that increases with the level and duration of the amplified spontaneous emission pedestal before the main laser pulse. In addition, for a given laser pulse, this beam deviation increases with proton energy. The observations are discussed in terms of different electron acceleration mechanisms and target normal sheath acceleration, in combination with a laser-controllable shock wave locally deforming the target rear surface.     

High resolution X-ray spectroscopy using synchrotron radiation: Source characteristics and optical systems

In this paper we describe the properties of the SPEAR storage ring at the Stanford Linear Accelerator Center as a synchrotron radiation source for X-ra