High resolution high field rodent cardiac imaging with flow enhancement suppression

A method that incorporates cardiorespiratory-gated 2DFT spin-echo imaging with blood flow enhancement suppression is described which enables high resolution microimaging of the rodent heart. This methodology was applied to obtain in vivo cardiac mouse and rat images with in-plane resolutions of 100–200 μm using high field vertical bore magnet systems. Suppression of intraventricular blood flow enhancement was achieved using a combined spin-echo/gradient-refocussed sequence to dephase magnetization from flowing spins prior to imaging.     

Gravity flow of coarse cohesionless granular materials in conical hoppers

This paper is concerned with the flow of cohesionless granular materials in conical hoppers. The granules are considered to be coarse such that the effects of interstitial fluid can be neglected. Two analytical approaches based upon the method of integral relations are presented. In the first the detailed variations of shear and normal stresses over the cross-section of the hopper are considered. The second is a very simple analysis which makes use of a mean normal stress averaged over the cross-section. The two analyses yield predictions for the flow rate which are almost identical. After the inclusion of an empirical correction factor to account for non-uniform exit velocity profiles and bulk density reductions near the outlet, the flow rate predictions and their variations with internal and wall friction angles and with hopper wall slope are found to agree well with experimental measurements.

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Résumé Cet article traite de l'écoulement de matières granuleuses sans cohésion dans des trémies coniques. On admet que les granules sont assez gros pour que les effets dûs au fluide intersistiel restent négligeables. 2 méthodes d'approche analytiques basées sur la méthode des relations intégrales sont présentées. La première considère en détail la distribution des contraintes normales et de cisaillement sur la section de la trémie. La seconde méthode est une simple analyse basée sur la moyenne des contraintes normales sur cette section. Les 2 analyses fournissent des prédictions presque identiques sur le taux d'écoulement. En introduisant un facteur de correction empirique pour tenir compte de la non-uniformité de profils de vitesses d'écoulement ainsi que de la réduction de densité à la sortie, l'analyse fournit des taux d'écoulement et leurs variations avec la friction interne, les angles de friction aux parois et l'inclinaison des parois de la trémie. Les résultants obtenus sont en accord avec des mesures expérimentales.

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On leave at the Department of Applied Mathematics and Theoretical Physics, University of Cambridge.     

Thermochemistry of fluorine compounds: IV. Rubidium tetrafluoroiodate

From measurement of the heat of hydrolysis, at 25°C , the enthalpy of formation of rubidium tetrafluoroiodate is derived: ΔH°_f [RbIF₄, cryst.]₂₉₈= ?191.12±4.43 kJ mol^?1. Heat capacity measurements for RbIF₄ over the range 273–303 K are also reported.     

2∶1 Complex of desoxycholic acid and ethyl acetate: Disorder in the structure at 298 and 163 K

The crystal structure of the 21 channel complex of desoxycholic acid and ethyl acetate has been investigated at 298 and 163 K. The space group isP2₁2₁2₁(No. 19) with four molecules of desoxycholic acid in the unit cell. The ethyl acetate molecules are enclathrated along the 2₁ axes parallel toc and exhibit differing degrees of disorder in the low- and room-temperature structures. Differences in the disorder imply that it is both statistical and dynamic in nature. Our best model for each structure yieldsR=0.064 [R _w =0.058,w=( ₂ F)^–1] andR=0.068 [R _w =0.064,w=( ² F) ^–1 ] for the ambient- and low-temperature studies respectively.IUPAC Nomenclature: 3, 12-dihydroxy-5-cholan-24-oic acid.     

New inflation in supersymmetric theories

A new inflationary universe scenario is considered based upon phase transitions in supersymmetric unified models where the Higgs potential is of the Witten-O'Raifeartaigh type.