Coherent and incoherent dynamics of excitons in semiconductor microcavities

Il Nuovo Cimento D - We have investigated the dynamics of impulsively excited planar microcavities in the strongly couple regime. With resonant, coherent excitation, the emitted light shows...     

Magnetic Bloch oscillations in nanowire superlattice rings

The recent growth of semiconductor nanowire superlattices encourages hope that Bloch-like oscillations in such structures formed into rings may soon be observed in the presence of a time-dependent magnetic flux threading the ring. These magnetic Bloch oscillations are a consequence of Faraday's law; the time-dependent flux produces an electromotive force around the ring, thus leading to the Bloch-like oscillations. In the spectroscopic domain, generalized Wannier-Stark states are found that are manifestations of the emf-induced localization of the states.     

Evidence for a new class of defects in highly n-doped Si: donor-pair-vacancy-interstitial complexes

Electron channeling experiments performed on individually scanned, single columns of atoms show that in highly n-type Si grown at low temperatures the primary electrically deactivating defect cannot belong to either the widely accepted class of donor-vacancy clusters or a recently proposed class of donor pairs. First-principles calculations suggest a new class of defects consisting of two dopant donor atoms near a displaced Si atom, which forms a vacancy-interstitial pair. These complexes are consistent with the present experimental results, the measured open volume of the defects, the observed electrical activity as a function of dopant concentration, and the enhanced diffusion of impurities in the presence of deactivated dopants.     

Gamma-ray spectroscopy with relativistic exotic heavy-ions

Feasibility of gamma-ray spectroscopy at relativistic energies with exotic heavy-ions and new generation of germanium detectors (segmented Clover) is discussed. An experiment with such detector array and radioactive is discussed.     

A multipotential hydrolytic reactor using the yeast strainKluyveromyces marxianus

In previous publications, we described the continuous production of D-fructose from enzymatic hydrolysis of inulin with immobilized permeabiliized cells ofKluyveromyces marxianus and the increase of productivity obtained by using a mutant selected by NTG action on the wild-type strain. By improving reactor performance, it has been possible to reach 2000 g/L/d of liberated sugar from an inulin solution with the mutant strain.

In addition, it has been shown that the KF 28 mutant was an invertase and pectinase hyperproducer. These enzymatic activities are also secreted by the speciesKluyveromyces marxianus. Therefore, we investigated the possibility of using immobilized cells of this yeast as a multipotential hydrolysis reactor. A sucrose hydrolysis reactor and a pectin hydrolysis reactor were set up. It is shown here that the majority of the optimized parameters from the inulin hydrolysis reactor can be transported directly to the other reactors. However, some parameters have to be adapted, especially for pectin hydrolysis.

     

Linear Conforming and Nonconforming Upwind Finite Elements for the Convection-Diffusion Equation

A conforming and a nonconforming method for the approximationof the stationary 2-D convection-diffusion equation at highP?clet number are presented. Convergence of order h is provedin a generic case and, for a particular choice of the upwindschemes, a discrete maximum principle is established under veryunrestrictive conditions on the mesh. Results of numerical computationsare produced to show the practical convergence of these methods.     

Measurement of ΔσL in pp scattering between 200 and 583 MeV

The main structure around m = 2.15 GeV first observed by the Argonne group in the spin-dependent total cross section Δσ_L is confirmed in the energy range available at SIN. A simultaneous study of the scattered particles at small angles has been carried out with success and gave the spin-correlation parameter A_00kk for the pp elastic scattering and for the reaction pp → π⁺d. The contribution of the 3-body reactions to this spin-dependent total cross section has been deduced and found to be lower than the contribution of the π⁺d reaction even at 583 MeV.     

Interatomic Auger transitions: A survey

A brief survey of the effects of interatomic Auger and Coster-Kronig transitions involving either the annihilation and/or ejection of electrons associated with the ligands nearest neighbor to the hole-state atom is presented. It is shown by way of example how these transitions may be used to interpret low energy Auger spectra of compound materials. Since these transitions affect the lifetime of certain core hole states, their probability should be reflected in their linewidths measured by x-ray photoelectron and x-ray emission spectroscopies. Dominant nonlifetime broadening processes generally preclude accurate determination of lifetime effects for most compounds u sing the former technique, but the latter spectroscopy may prove useful for studying such effects from the linewidths of characteristic x-rays and the intensities of multiple-hole x-ray satellite lines in certain materials.