A hyperbolic surface with a square grid net

We prove the existence of a hyperbolic surface spread over the sphere for which the projection map has all its singular values on the extended real line and such that the preimage of the extended real line under the projection map is homeomorphic to the square grid in the plane. This answers a question raised by è. B. Vinberg. Supported by the Alexander von Humboldt Foundation. Supported by NSF grants DMS-0400636, DMS-0244421, and DMS-0244547.     

On the computation of electronic excitations in solids

An approximation scheme is proposed for calculating electronic excitations in solids. It is described within a projection operator formalism of the Mori-Zwanzig type. The approximation consists in successively limiting the space of dynamical variables which are treated. The selection of the variables is done by making use of the local character of the correlation hole which is surrounding an electron. The method is distinct from a perturbation expansion and can be related to a variational ansatz via the Sauermann functional. The computation of the spectral density of the Green's function is reduced to the diagonalization of matrices. Their dimension depends on the required degree of accuracy of the calculations. The present method can be considered as an extension to excited states of a previously developed. Local Approach for ground state calculations.Dedicated to Prof. S. Methfessel on the occasion of his 60th birthday     

Continuous proton spectra emitted in 3He and deuteron induced reactions

A study of the energy and angular distributions of protons emitted in ³He induced reactions was undertaken at an incident energy of 25.6 MeV. An analysis in the framework of the pre-equilibrium hybrid model did not succeed in explaining the overall behaviour of proton spectra; a contribution due to a break-up or a double stripping of the incident particle has to be taken into account. An attempt was made to account for these processes by performing a phase space calculation. This formulation was firstly tried in the case of deuteron induced reactions for which a break-up mechanism has already been confirmed in continuous proton spectra. The calculation extended to the case of ³He induced reactions showed that a double stripping mechanism could explain the observed distribution.     

Improvement of Injection-Locked VCSELs for Analog and Digital Communication Systems

VCSEL Injection locking is demonstrated to increase laser bandwidth and reduce non-linearity and chirp.All these properties enhance analog and digital modulation performance.     

Quantitative detection of phosphoproteins by combination of two-dimensional difference gel electrophoresis and phosphospecific fluorescent staining

Here we combine a standard two-dimensional difference gel electrophoresis (DIGE) protocol with subsequent post-staining of gels with phosphospecific fluorescent Pro-Q Diamond dye. The combination of these two methods for fluorescence detection of proteins allows quantitative detection of phosphoproteins in 2-DE-gels. We established this protocol within a functional proteomics experiment. Mammary epithelial cells (EpH4) were stimulated in culture by epidermal growth factor (EGF), endosomal fractions prepared after subcellular fractionation and phosphorylated proteins successfully detected on endosomes. For instance, Endo A cytokeratin, known as phosphoprotein and differentiation marker inducible by MAPK signaling, was identified by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). With this protocol, all steps of combined proteome and phosphoproteome profiling experiments are significantly simplified and accelerated, taking full advantage of both methods in terms of specificity, sensitivity and accuracy of quantification.     

The palladium-catalyzed cross-coupling reaction of carboxylic anhydrides with arylboronic acids: a DFT study

The mechanism of the cross-coupling of phenylboronic acid with acetic anhydride, a viable model of the widely used Suzuki reaction, has been studied by DFT calculations at the BP86/6-31G level of theory. Two alternative catalytic cycles have been investigated, one starting from a neutral Pd(0)L(2) complex, the other from an anionic "Jutand-type" [Pd(0)L(2)X](-) species. The reaction profiles are in good agreement with the experimental findings, as both pathways require only moderate activation energies. Both pathways are dominated by cis-configured square-planar palladium(II)diphosphine intermediates. Despite careful investigations, we did not find in this model reaction any evidence for five-coordinate palladium(II) intermediates, which are commonly believed to cause the profound effects of counterions in palladium-catalyzed transformations. Instead, our calculations suggest that the higher catalytic activity of anionic complexes, such as [Pd(PMe(3))(2)OAc](-), may arise from their stronger ability to coordinate to carbon electrophiles. The transmetalation sequence is the same for both catalytic cycles, involving the dissociation of one phosphine ligand from the palladium. In the decisive transition state, in which the phenyl group is transferred from boron to palladium, the acetate base is found to be in a bridging coordination between these two atoms.     

Awakening effects of simulated sonic booms and aircraft noise on men and women

In the course of several studies, 22 male and female subjects, ranging in age from 5–75 years, have been stimulated while asleep by simulated sonic booms (ranging in intensity from 0·6 to 5·0 lb/ft² (239·5 N/m²), as if measured out of doors at ground level) and by indoor recordings of subsonic jet flyover noise (ranging in intensity from 101 to 119 PNdB, as if measured out of doors). The summarized results of these studies suggest that (i) children (5–8 years of age) are uniformly unaffected by noise during sleep; (ii) older subjects are more sensitive to noise than younger subjects; (iii) women are more sensitive to noise during sleep than are men; (iv) within an age group, individuals may vary widely with respect to their relative sensitivities to noise during sleep; and (v) the frequency of behavioral awakening is a function of the intensity of both the simulated sonic booms and the subsonic jet flyover noise.