Exact reconstruction in photoacoustic tomography with circular integrating detectors II: Spherical geometry

Illuminating tissue with pulsed electromagnetic waves generates acoustic waves inside an object which can be measured and converted into a three‐dimensional (3d) image. This text is concerned with a two‐step reconstruction method where the acoustic pressure is measured with circular integrating detectors. In the first step, reconstruction formulas for some kind of projection of the source distribution are derived; in the second step, an inversion formula for a circular radon transform on the sphere is developed. Copyright © 2010 John Wiley & Sons, Ltd.     

Beiträge zur Chemie der Pyrrolpigmente, 7. Mitt.: Struktur und Elektronen-Absorptionsspektren von Pyrromethenderivaten

The electron absorption spectra of pyrromethenes can be calculated satisfactorily using thePPP-SCF-LCAO-MO-CI-method. Using different choices of parameters, a set of parameters was established giving excellent agreement between theoretical and experimental spectra of symmetrically substituted α,α′-dipyrromethenes. Slightly modified sets of parameters are suitable for the calculation of the electron absorption spectra of protonated pyrromethenes, metal chelates of pyrromethenes and others where no N—H ... N-bridge can be formed or which are unsymmetrically substituted. In the case of the chelates it could be demonstrated that the rather complicated structure of the spectra can be rationalized on the basis of the geometrical alignment of the ligands. Calculations on all possible conformers of α,α′-pyrromethenes revealed no significant differences of the absorption spectra.     

Silvaglenamin—a novel dimeric triterpene alkaloid from Aglaia silvestris

An unusual dimeric triterpene structure with two dammarane units linked with an enaminic -NH- group was isolated from the root extract of Aglaia silvestris. The structure was elucidated by 1D and 2D NMR analysis and ESI mass spectrometry.     

On the conformational flexibility of vitamin D

The conformational flexibility of vitamin D was investigated by a combination of force field calculations, LIS measurements and LIS simulations. Besides the two A-ring chair forms, A-ring twist forms were detected and were attributed to steric interactions arising from the substitution pattern of this class of seco-steroids.

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Über die konformationelle Beweglichkeit von Vitamin D

Zusammenfassung Die konformationelle Beweglichkeit von Vitamin D wurde mittels einer Kombination aus Kraftfeld Rechnungen, LIS-Messungen und LIS-Rechnungen untersucht. Neben den beiden A-Ring Sesselformen wurden auch A-Ring Twistformen aufgefunden. Die Ursache für das Vorhandensein von diesen Twistformen liegt in sterischen Wechselwirkungen, verursacht durch das Substitutionsmuster des A-Ringes in diesem seco-Steroid.

     

Large cardinals and projective sets

We investigate measure and category in the projective hierarchie in the presence of large cardinals. Assuming a measurable larger than Woodin cardinals we construct a model where every -set is measurable, but some -set does not have Baire property. Moreover, from the same assumption plus a precipitous ideal on we show how a model can be forced where every set is measurable and has Baire property. Received October 12, 1994     

On the structure theory of the Iwasawa algebra of a p-adic Lie group

This paper is motivated by the question whether there is a nice structure theory of finitely generated modules over the Iwasawa algebra, i.e. the completed group algebra, Λ of a p-adic analytic group G. For G without any p-torsion element we prove that Λ is an Auslander regular ring. This result enables us to give a good definition of the notion of a pseudo-nullΛ-module. This is classical when G=ℤ ^k _p for some integer k≥1, but was previously unknown in the non-commutative case. Then the category of Λ-modules up to pseudo-isomorphisms is studied and we obtain a weak structure theorem for the ℤ _p -torsion part of a finitely generated Λ-module. We also prove a local duality theorem and a version of Auslander-Buchsbaum equality. The arithmetic applications to the Iwasawa theory of abelian varieties are published elsewhere. Received May 12, 2001 / final version received July 5, 2001?Published online September 3, 2001     

Impact of aging on cardiac high-energy phosphate metabolism determined by phosphorus-31 2-dimensional chemical shift imaging (31P 2D CSI)

Previous echocardiographic and experimental animal studies have shown that cardiac function, structure, and metabolism change with age. The aim of this study was to evaluate the impact of age on left ventricular high-energy phosphate metabolism. Using a 1.5 Tesla whole-body MR scanner 31P 2D CSI (8 x 8 phase encoding steps, 320 mm field of view) was performed in 76 healthy male volunteers (41.7 +/- 13 years) without any history of coronary heart disease. Fourier interpolation, corrections for T1 saturation effects, the nucleus Overhauser effect, and the blood contamination were applied to the spectroscopic data. The volunteers were divided into two groups, younger (n = 37) and older (n = 39) than 41.7 years. In all volunteers, laboratory specimen were sampled, and transthoracal echocardiography was carried out. Significant differences in left ventricular phosphocreatine (PCr) to beta-adenosine-triphosphate (beta-ATP) ratios (2.16 vs. 1.83, p < 0.001), fasting serum glucose levels (83.3 vs. 98.7 mg/dl, p < 0.001), E/A (1.51 vs. 1.14 p < 0.001), and ejection fraction (EF, 65.3 vs. 59.9%, p = 0.005) were detected between the two groups of volunteers, younger and older than 41.7 years. Moreover, age correlated moderately to well with left ventricular PCr to beta-ATP ratios (r = -0.44), fasting serum glucose levels (r = 0.4), E/A (r = -0.7), left ventricular myocardial mass (r = -0.41), and EF (r = -0.55). In conclusion, our study shows that left ventricular PCr to beta-ATP ratios decrease moderately with age, as suggested by previous experimental animal studies. Additionally, age correlates negatively with E/A, left ventricular myocardial mass, and EF, as reported by previous echocardiography studies. The present study is the first to show the impact of age on left ventricular PCr to beta-ATP values in humans.     

Beiträge zur Chemie der Pyrrolpigmente, 18. Mitt.: Pyrromethenone—Partialstrukturen von Gallenpigmenten: Struktur und Eigenschaften in Lösung

Depending on solvent polarity and concentration a monomer—dimer equilibrium for pyrromethenones was deduced by means of absorption and fluorescence spectroscopy and measurement of a colligative property. The monomer could be characterized as asyn-(Z) form with a dihedral angle at the methine single bond of about fourty degrees using the lanthanide shift technique and nuclearOverhauser effect studies. Two types of dimer geometry with differing bond strengths were found by comparingPPP calculation results with the measured absorption spectra and the liquid crystal induced circular dichroism.The (Z) isomers can be transformed to the corresponding (E) isomers by means of a photoreaction. The latter is thermally stable but rather sensitive against oxygen, light and protons, an effect which varies strongly with the substitution pattern of the pyrrole fragment thus enabling isolation in certain cases only.

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Mit 7 Abbildungen     

Modelluntersuchungen zur Simulierung von LIS. II.1 2-, 3-und 7-substituierte 1-Indanone

The space close to the coordination site of1-indanone is modified systematically by placing alkyl groups of different bulkiness on C-2, C-3 and C-7, resp. The¹H-LIS for the compounds are interpreted using the one site and two site model for carbonyl. Precautionary measures are discussed for both models to give reliable results in the calculation.

Herrn Prof.O. E. Polansky mit den besten Wünschen zum 60. Geburtstag gewidmet.