Untersuchung eines lokalen Maximums der Szintillationslichtausbeute von Anthrazeneinkristallen bei Beschuß mit α-Teilchen

The scintillation light yield of anthracene single crystals excited by 8.78 MeV α-particles and its dependence on particle impact direction is investigated. Special attention is paid to a local maximum of the scintillation light yield first observed by Kienzle. The local maximum is found to occur exactly in the (a, b)-plane. This is confirmed in the temperature range from 14 to 90 °K. According to a theory by Bönsch this local maximum is explained by anisotropic diffusion of triplet excitons. In the interpretation of the local maximum channeling effects should be excluded.     

A Hierarchy of Plate Models Derived from Nonlinear Elasticity by Gamma-Convergence

We derive a hierarchy of plate models from three-dimensional nonlinear elasticity by Γ-convergence. What distinguishes the different limit models is the scaling of the elastic energy per unit volume ∼h^β, where h is the thickness of the plate. This is in turn related to the strength of the applied force ∼h^α. Membrane theory, derived earlier by Le Dret and Raoult, corresponds to α=β=0, nonlinear bending theory to α=β=2, von Kármán theory to α=3, β=4 and linearized vK theory to α>3. Intermediate values of α lead to certain theories with constraints. A key ingredient in the proof is a generalization to higher derivatives of our rigidity result [29] which states that for maps v:(0,1)³→ℝ³, the L² distance of ∇v from a single rotation is bounded by a multiple of the L² distance from the set SO(3) of all rotations.     

A theorem on geometric rigidity and the derivation of nonlinear plate theory from three‐dimensional elasticity

The energy functional of nonlinear plate theory is a curvature functional for surfaces first proposed on physical grounds by G. Kirchhoff in 1850. We show that it arises as a Γ‐limit of three‐dimensional nonlinear elasticity theory as the thickness of a plate goes to zero. A key ingredient in the proof is a sharp rigidity estimate for maps v : U → ?ⁿ, U ? ?ⁿ. We show that the L²‐distance of ?v from a single rotation matrix is bounded by a multiple of the L²‐distance from the group SO(n) of all rotations. © 2002 Wiley Periodicals, Inc.     

Convolution-Dominated Operators on Discrete Groups

We study infinite matrices A indexed by a discrete group G that are dominated by a convolution operator in the sense that for x ∈ G and some . This class of “convolution-dominated” matrices forms a Banach-*-algebra contained in the algebra of bounded operators on ℓ ²(G). Our main result shows that the inverse of a convolution-dominated matrix is again convolution-dominated, provided that G is amenable and rigidly symmetric. For abelian groups this result goes back to Gohberg, Baskakov, and others, for non-abelian groups completely different techniques are required, such as generalized L ¹-algebras and the symmetry of group algebras. K. G. was supported by the Marie-Curie Excellence Grant MEXT-CT 2004-517154.     

Dried blood spot UHPLC-MS/MS analysis of oseltamivir and oseltamivircarboxylate—a validated assay for the clinic

The neuraminidase inhibitor oseltamivir (Tamiflu®) is currently the first-line therapy for patients with influenza virus infection. Common analysis of the prodrug and its active metabolite oseltamivircarboxylate is determined via extraction from plasma. Compared with these assays, dried blood spot (DBS) analysis provides several advantages, including a minimum sample volume required for the measurement of drugs in whole blood. Samples can easily be obtained via a simple, non-invasive finger or heel prick. Mainly, these characteristics make DBS an ideal tool for pediatrics and to measure multiple time points such as those needed in therapeutic drug monitoring or pharmacokinetic studies. Additionally, DBS sample preparation, stability, and storage are usually most convenient. In the present work, we developed and fully validated a DBS assay for the simultaneous determination of oseltamivir and oseltamivircarboxylate concentrations in human whole blood. We demonstrate the simplicity of DBS sample preparation, and a fast, accurate and reproducible analysis using ultra high-performance liquid chromatography coupled to a triple quadrupole mass spectrometer. A thorough validation on the basis of the most recent FDA guidelines for bioanalytical method validation showed that the method is selective, precise, and accurate (≤15% RSD), and sensitive over the relevant clinical range of 5–1,500 ng/mL for oseltamivir and 20–1,500 ng/mL for the oseltamivircarboxylate metabolite. As a proof of concept, oseltamivir and oseltamivircarboxylate levels were determined in DBS obtained from healthy volunteers who received a single oral dose of Tamiflu®.