Twisted N=2 Supersymmetry with Central Charge and Equivariant Cohomology

We present an equivariant extension of the Thom form with respect to a vector field action, in the framework of the Mathai-Quillen formalism. The associated Topological Quantum Field Theories correspond to twisted N=2 supersymmetric theories with a central charge. We analyze in detail two different cases: topological sigma models and non-abelian monopoles on four-manifolds. Received: 2 April 1996 / Accepted: 15 July 1996     

Black hole/string transition for the small Schwarzschild black hole of AdS 5 × S5 and critical unitary matrix models

In this paper we discuss the black hole–string transition of the small Schwarzschild black hole of AdS ₅×S⁵ using the AdS/CFT correspondence at finite temperature. The finite temperature gauge theory effective action, at weak and strong coupling, can be expressed entirely in terms of constant Polyakov lines which are SU(N) matrices. In showing this we have taken into account that there are no Nambu–Goldstone modes associated with the fact that the 10-dimensional black hole solution sits at a point in S⁵. We show that the phase of the gauge theory in which the eigenvalue spectrum has a gap corresponds to supergravity saddle points in the bulk theory. We identify the third order N=∞ phase transition with the black hole–string transition. This singularity can be resolved using a double scaling limit in the transition region where the large N expansion is organized in terms of powers of N^-2/3. The N=∞ transition now becomes a smooth crossover in terms of a renormalized string coupling constant, reflecting the physics of large but finite N. Multiply wound Polyakov lines condense in the crossover region. We also discuss the implications of our results for the resolution of the singularity of the lorenztian section of the small Schwarzschild black hole.     

Sol–gel routes for microporous zirconia and titania membranes

Zirconia and titania nanoparticle sols were prepared, using either ligand-based precursor stabilization or acid stabilization routes. These sols were used to prepare microporous coatings on γ-alumina substrates. The acetylacetonate-based particles have very small hydrodynamic diameters (1–2 nm), which lead to sol intrusion into the supports. As a result no appropriate membrane layer was formed. A microemulsion-based zirconia sol leads to a membrane that was selective in pervaporation dehydration of a water/n-butanol mixture. An optimized membrane showed stable separation performance for 120 days with a high selectivity toward water. Permporometry and gas permeation results on a titania membrane based on an acid-stabilized sol not only show microporosity, but also a significant contribution from defect flow.     

Groups with finitely many normalizers of non-abelian subgroups

Abstract A group is called metahamiltonian if all its non-abelian subgroups are normal; it is known that locally soluble metahamiltonian groups have finite commutator subgroup. Here the structure of locally graded groups with finitely many normalizers of (infinite) non-abelian subgroups is investigated, and the above result is extended to this more general situation. Keywords: normalizer subgroup, metahamiltonian group Mathematics Subject Classification (2000): 20F24     

Phenolics from Castanea sativa leaves and their effects on UVB-induced damage

The phytochemical investigation of the methanol extract of the leaves of Castanea sativa Mill., source of the Italian PGI (Protected Geographical Indication) product ‘Marrone di Roccadaspide’ (Campania region) afforded as main compounds crenatin (1), chestanin (2), gallic acid (3), cretanin (4), 5-O-p-coumaroylquinic acid (5), p-methylgallic acid (6) and quercetin-3-O-glucoside (7). To quantify the isolated compounds a LC-ESI(QqQ)MS method working with a very sensitive and selective mass tandem experiment called Multiple Reaction Monitoring (MRM) has been developed. Moreover the antioxidant capacity by TEAC assay and the ability of compounds 1–7 to protect HaCaT human keratinocytes from UVB-induced damage has been investigated.     

Influence of simulated microgravity on the activation of the small GTPase Rho involved in cytoskeletal formation – molecular cloning and sequencing of bovine leukemia-associated guanine nucleotide exchange factor

Background  

The irregular formation of cytoskeletal fibers in spaceflown experimental cells has been observed, but the disorganization process of fibers is still poorly understood. It is well known that the activation of the small GTPase Rho leads to actin stress fibers assembly. This study was performed to evaluate the effect of simulated microgravity on the activation of Rho that is involved in actin fiber remodeling in cells.     

A convenient synthesis of novel spiro[benzoxazole-2′,4(1H,3′H)-pyrazolo[5,1-c][1,2,4]triazines] by ring transformation of novel pyrazolo[1′,5′:3,4][1,2,4]triazino[5,6-b][1,5]benzoxazepines

Novel pyrazolo[1′,5′:3,4][1,2,4]triazino[5,6-b][1,5]benzoxazepines 5, 6 and 8 were synthesized, and these compounds were converted into novel spiro[benzoxazole-2′,4(1H,3′H)-pyrazolo[5,1-c][1,2,4]triazines] 7 and 9 by ring transformation.