P-harmonic obstacle problems

We prove an extension theorem for Sobolev functions which plays an important role in the partial regularity theory of vector valued functions which minimize degenerate variational integrals subject to some nonlinear side conditions in the image space.     

Book reviews

Ohne Zusammenfassung

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Book reviews

     

Separation of rat pancreatic secretory proteins by cation-exchange fast protein liquid chromatography.

Rat pancreatic secretory proteins were separated by an automated liquid chromatography system utilizing a Mono S cation-exchange column. Optimal resolution was obtained with a multistep salt and pH gradient (0.01-2 M LiCl, pH 5.3-63). A total of fourteen well-separated peaks, as well as several minor peaks, were detected by UV absorption. The main pancreatic enzymes were resolved (two amylases, two chymotrypsinogens, two trypsinogens, proelastase, lipase, prophospholipase A2, procarboxypeptidase A, procarboxypeptidase B, and ribonuclease). In addition, proteins without enzymic activity, such as lithostathine and pancreatitis-associated protein, were identified. Activation of proenzymes did not occur during the separation. At a flow-rate of 0.5 ml/min, ca. 250 micrograms to 5 mg of protein could be applied with equal resolution. The reproducibility of retention volumes and peak areas was high (less than 1% or 5% variation, respectively). When radiolabeled proteins were separated, a comparable pattern of peaks was obtained. The technique described is, therefore, not only useful for analytical and preparative separation of pancreatic proteins but can additionally serve for quantitative determination of the pancreatic isoenzyme pattern.     

Analysis and interpretation of new low-energy \pi\pi scattering data

The recently published E865 data on charged decays and phases are reanalyzed to extract values of the two S-wave scattering lengths, of the subthreshold parameters and , of the low-energy constants and as well as of the main two-flavour order parameters: and in the limit taken at the physical value of the strange quark mass. Our analysis is exclusively based on direct experimental information on phases below 800 MeV and on the new solutions of the Roy equations by Ananthanarayan et al. The result is compared with the theoretical prediction relating 2a ₀ ⁰-5a ₀ ² and the scalar radius of the pion, which was obtained in two-loop Chiral Perturbation Theory. A discrepancy at the 1- level is found and commented upon. Received: 11 December 2001 / Revised version: 28 March 2002 / Published online: 7 June 2002     

InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

The first fully operational mid-IR (3–5 μm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement. The paper presented there appears in Infrared Photoelectronics, edited by Antoni Rogalski, Eustace L. Dereniak, Fiodor F. Sizov, Proc. SPIE Vol. 5957, 595707 (2005).     

Die zwischenmolekularen Kräfte und die physikalischen Eigenschaften makromolekularer Stoffe

Colloid and Polymer Science - Nach einer Aufzählung der verschiedenen Arten von zwischenmolekularen Kräften und dem Hinweis auf die Gültigkeitsgrenze der bestehenden Vorstellungen...     

Borel fibrations and G-spaces

Considering discrete groups G only, we present an elementary proof of the familiar equivalence of the category of G-spaces (with maps equivariant up to homotopy) and the category of Borel fibrations over BG.     

Free fermions and WZW theories on nonsimple groups

We consider conformally and Kac-Moody invariant theories based on the groupsG=G(N)×G(Ñ) whereG(N) is any of the classical groups. For the valuesk=Ñ, \(\tilde k = N\) of the Kac-Moody central charges, the monodromy problem involved in the computation of the four point function for primary fields in the defining representation ofG possesses two distinct solutions. As a consequence, the WZW theory onG (with an additionalU(1) factor ifG(N)=SU (N)) cannot be equivalent to a theory of free fermions.     

Stereoelectronic effects in negatively and positively (Protonated) charged species. Ab initio studies of the gauche effect in 1,4-dioxa systems

A computational study ab initio of the conformational dependence of proton affinities of 2-methoxyethoxide (MEO), dimethoxyethane (DME), and 1,4-dioxane has been carried out at the MP2/6-31+G level of theory. The results were discussed in comparison with reference systems, from simple alkoxides and ethers to anomeric moieties, in open, cyclic, and bicyclic molecules. The COCCOC species are stronger bases than the COCOC (anomeric) ones and approach regular ethers in their strength. The gauche forms in MEO and DME are altogether stronger bases than the anti forms, and anti (equatorial) protonation is preferred over gauche (axial), unless ditopic protonation is possible, like in aga-DME or cis-tetraoxadecalin. The gauche effect plays a significant role in the formation, relative stability, and reactivity of the charged species.