Parabolic induction and Jacquet functors for metaplectic groups

In this paper, we give a new formulation of a geometric lemma for the metaplectic groups over p-adic field F, analogous to the existing one for classical groups. This enables us to give a Zelevinsky type classification of irreducible admissible genuine representations of metaplectic groups. As an application of our Jacquet module technique, we explicitly calculate Jacquet modules of even and odd Weil representations.     

Air-borne sound source characterization by patch impedance coupling approach

An approach of independent sound source characterization is discussed. The source is defined by its blocked sound pressure and surface impedance via a suitable enveloping surface. Both the blocked pressure and the impedance are made discrete using the patch averaging concept. The approach is adapted to numerical as well as experimental implementation. The characterization of a source by patches allows for acoustical sub-structuring, which in turn enables the prediction of the sound field created by a source coupled to an arbitrary environment. Numerical simulations are presented which demonstrate the validity of the approach.     

Design of a new fluorescent cofactor for DNA methyltransferases and sequence-specific labeling of DNA

Sequence-specific labeling of DNA is of immense interest for analytical and functional studies of DNA. We present a novel approach for sequence-specific labeling of DNA using a newly designed fluorescent cofactor for the DNA methyltransferase from Thermus aquaticus (M.TaqI). Naturally, M.TaqI catalyzes the nucleophilic attack of the exocyclic amino group of adenine within the double-stranded 5'-TCGA-3' DNA sequence onto the methyl group of the cofactor S-adenosyl-L-methionine (AdoMet) leading to methyl group transfer. The design of a new fluorescent cofactor for covalent labeling of DNA was based on three criteria: (1) Replacement of the methionine side chain of the natural cofactor AdoMet by an aziridinyl residue leads to M.TaqI-catalyzed nucleophilic ring opening and coupling of the whole nucleoside to DNA. (2) The adenosyl moiety is the molecular anchor for cofactor binding. (3) Attachment of a fluorophore via a flexible linker to the 8-position of the adenosyl moiety does not block cofactor binding. According to these criteria the new fluorescent cofactor 8-amino[1'-(N'-dansyl)-4'-aminobutyl]-5'-(1-aziridinyl)-5'-deoxyadenosine (3) was synthesized. 3 binds about 4-fold better than the natural cofactor AdoMet to M.TaqI and is coupled with a short duplex oligodeoxynucleotide by M.TaqI. The identity of the expected modified nucleoside was verified by electrospray ionization mass spectrometry after enzymatic fragmentation of the product duplex. In addition, the new cofactor 3 was used to sequence-specifically label plasmid DNA in a M.TaqI-catalyzed reaction.     

Crystallographic/experimental electron density characterizations and reactions with nucleophiles of beta-enaminonitriles possessing a pyrrolobenzazepine core

In connection with a total synthesis of cephalotaxine (1a), we have examined the addition of various nucleophilic reagents to [ABC] subunits 2 and 7 possessing a pyrrolobenzazepine core. In fact, this reaction implicates invariably the carbonyl group of 2. Regarding the reaction of 7 with nucleophiles, the most striking aspect is the complete lack of reactivity of the enaminonitrile moiety. For instance, the condensation of 7 with methylmagnesium bromide involves exclusively the cleavage of the dioxole ring, yielding regioisomers 9 and 10. With the aim of understanding the unexpected reactivity of 2 and 7 toward nucleophiles, crystallographic studies of 2 and 7 and an experimental electron density determination of 7 were carried out. The marked reactivity of the carbonyl group of 2 was interpreted by invoking the weakness of the amide resonance, due to a pronounced delocalization of the N(9) lone pair over the enaminonitrile moiety. The electron density study of 7 reveals this electron delocalization along the enaminonitrile fragment, highlighted and quantified through the bond geometries, topological indicators, and atomic charges, a phenomenon that is responsible for the failure of the addition of nucleophilic species.     

Evaluation of novel sample identification approach based on chromatographic fingerprint set correlation homogeneity analysis

Instead of usual rationale for chromatographic fingerprint based sample identification which relies upon visual inspection or principal component analysis of raw or aligned chromatograms novel nonparametric statistical measure of fingerprint set homogeneity is proposed. Randomization test is applied for significance analysis of fingerprint set homogeneity while average maximum crosscorrelation is used as a merit function. Chromatogram sets generated by random selection from standard and unknown sample chromatogram collections are compared with respect to merit function values with set of chromatograms that represents standard and/or unknown sample. In that instance fingerprint homogeneity significance is represented by the fraction of random chromatogram sets that have higher merit values than the standard and/or unknown sample sets. A set of peptide maps corresponding to different haemoglobin variants has been selected for evaluation of proposed test. This approach is compared to chromatogram alignment based on correlation optimized warping coupled with principal component or cluster analysis. Proposed method is simple i.e. straightforward sample identification procedure which reliability has been evaluated here. Impact of this approach on peptide mapping validation and system suitability analysis is discussed.     

Physico-chemical processes in metal-oxide-semiconductor transistors with thick gate oxide during high electric field stress

A complete study of the defects created in the gate oxide and at the gate oxide/substrate interface of metal-oxide-semiconductor transistors with thick gate oxide (t_ox > 10 nm) during high electric field stress, and the mechanisms responsible for these defects creation have been given. In addition, some results of positive/negative high electric field stress with constant gate voltage of commercial n-channel power metal-oxide-semiconductor transistors with thick gate oxide of 100 nm, have been explained using this study.     

Molecular recognition directed self-assembly of tubular supramolecular architectures from building blocks containing monodendrons as exo-receptors and crown- or pseudo-crown-ethers as endo-receptors

The principles of self-assembly of tapered exo-receptors constructed from monodendrons containing crown-ether, oligooxyethylenic groups and polymer backbones as endo-receptors into tubular supramolecular architectures are described with selected examples. In the case of polymers with flexible backbones it is suggested that a helical chain conformation is induced during the assembly of its own tapered side groups. This mechanism is supported by the enhanced self-assembling ability of tapered side groups attached to a backbone with rigid helical conformation.     

Bond profiles for cuboctahedron and twist cuboctahedron

Using the information on the interatomic separations in a molecule, one can construct structural invariants that are the components of a molecular profile. The entries in the profile are derived by averaging different powers of the interatomic separations, suitably normalized so that the increasing powers do not dominate the sequence. Although only a few hundreds of structures have been so analyzed, no two different chemical structures were found to be characterized by the same sequences. A critical test for the conjecture that molecular profiles are unique is to consider structurally closely related systems that are very similar and have several similar properties. In this contribution we investigated the cuboctahedron and the accompanying polyhedron obtained by rotating half of the cuboctahedron against the other half, resulting in the so-called twist cutoctahedron. We show that even this pair of closely related structures has different profiles. We have also examined the generalized molecular profiles obtained by inserting n additional points along each edge of the polyhedra. The convergence of the profiles as n increases is discussed. It appears thus that these generalized molecular profiles, called line profiles or bond profiles, are likely to lead to a unique characterization of structures in which not only the geometry of atoms is recorded but also the geometry of the connectivity of the structure. © 1996 John Wiley & Sons, Inc.     

Defect behaviors in n-channel power VDMOSFETs during HEFS and thermal post-HEFS annealing

The results of positive/negative Fowler-Nordheim high electric field stress and thermal post-high electric field stress annealing of commercial n-channel power VDMOSFETs have been presented. They have shown that gate bias sign has an influence on the fixed trap behavior during high electric field stress, but has no influence on any defect type behavior during thermal post-high electrical field stress annealing. In addition, slow switching traps have different behavior, but fast switching traps have the same behavior during thermal post-high electrical field stress annealing and thermal post-irradiation annealing.