Inelastic proton scattering to the lowest 1+ state in58Ni

A microscopic, antisymmetrized Distorted Wave approximation is used in an analysis of the inelastic scattering of 17.8 MeV protons from⁵⁸Ni in which the 1⁺ (2.90 MeV) state is excited. Two step resonance amplitudes complement the usual direct reaction transition amplitudes in this analysis. In particular, resonance amplitudes associated with the virtual excitation of a giant dipole and of a giant octupole resonances are considered, and are essential for the model to fully explain the experimental data.     

Neighborly combinatorial 3-manifolds with 9 vertices

A complete classification is given for neighborly combinatorial 3-manifolds with 9 vertices. It is found that there are 51 types, only one of which is not a sphere.     

(+)-Sorangicin A synthetic studies. Construction of the C(1-15) and C(16-29) subtargets

[structure: see text] Effective stereocontrolled syntheses of subtargets (-)-2 and (-)-4, comprising respectively the C(16-29) and C(1-15) tetrahydropyran and dihydropyran moieties of the potent antibiotic (+)-sorangicin A (1), have been achieved. The cornerstone for the synthesis of (-)-2 involved an aldol tactic exploiting 1,4-induction, followed in turn by an acid-mediated cyclization/ketalization and hydrosilane reduction promoted by TMSOTf, while construction of (-)-4 entailed a stereoselective conjugate addition/alpha-oxygenation sequence.     

Microtubule structure and its stabilisation

Microtubules are designed to be dynamically unstable. GTP hydrolysis converts an initially stable polymeric structure into an unstable one in which strain at the interfaces between longitudinal neighbours in the helical lattice of subunits is balanced by lateral interactions. However, stability can be modulated by a variety of factors, including associated proteins and a variety of drug molecules. Stabilising drugs such as Taxol and the assembly-promoting repeat motifs of tau protein occupy a special pocket in beta-tubulin. Microtubule destabilizing drugs such as colchicine alter the longitudinal interfaces of the subunits so that they cannot assemble into a microtubule lattice. These mechanisms are discussed in terms of the atomic structure of the protein.     

Anomalous proximity effect in gold coated (110) YBa2Cu3O7-delta films: penetration of the Andreev bound states

Scanning tunneling spectroscopy of (110)YBa(2)Cu(3)O(7-delta)/Au bilayers reveal a proximity effect markedly different from the conventional one. While proximity-induced mini-gaps rarely appear in the Au layer, the Andreev bound states clearly penetrate into the metal. Zero bias conductance peaks are measured on Au layers thinner than 7 nm with a magnitude similar to those detected on the bare superconductor films. The peaks then decay abruptly with Au thickness and disappear above 10 nm. This length is shorter than the normal coherence length and corresponds to the (ballistic) mean free path.     

Search for heavy particles decaying into electron-positron pairs in pp collisions

We present results of searches for technirho (rho(T)), techniomega (omega(T)), and Z' particles, using the decay channels rho(T),omega(T),Z'-->e(+)e(-). The search is based on 124.8 pb(-1) of data collected by the D0 detector at the Fermilab Tevatron during 1992-1996. In the absence of a signal, we set 95% C.L. upper limits on the cross sections for the processes pp-->rho(T),omega(T),Z'-->e(+)e(-) as a function of the mass of the decaying particle. For certain model parameters, we exclude the existence of degenerate rho(T) and omega(T) states with masses below about 200 GeV. We exclude a Z' with mass below 670 GeV, assuming that it has the same couplings to fermions as the Z boson.     

Frequency-dependent properties of the hydrogen atom: A generalized eigenvalue equation approach

The time-independent first-order perturbation equations which arise on considering the response of a system to a harmonic time-dependent perturbation are solved by using an expansion in terms of a complete discrete set of solutions of a generalized eigenvalue equation. Explicit formulae are obtained for several frequency-dependent properties of the hydrogen atom.     

Untersuchung von Mehl

Ohne Zusammenfassung