Spasmodic dysphonia and vocal fold paralysis:Outcomes of voice problems on work-related functioning

Patients at a university voice disorder clinic diagnosed with spasmodicdysphonia (SD, n = 68) or vocal fold paralysis (VFP, n = 57) reported vocal symptoms and adverse work outcomes in contrast to a nondisordered group (ND, n = 68). Patients with SD most frequently cited symptoms of effortfulness (57%) and weakness (54%), VFP cited hoarseness (70%) and weakness (60%), while the nondisordered reported hoarseness (28%). SD and VFP produced greater (p<.05) adverse work outcomes than the nondisordered in the past (SD: 65%, VFP: 41%, ND: 3%), potential future (SD: 78%, VFP: 65%, ND: 19%), and current job performance (SD: 64%, VFP: 46%, ND: 2%). These disorders significantly disrupt socioeconomic outcomes and research is needed to improve functional ability and quality of life.     

Femtosecond dynamics of secondary radiation formation from quantum well excitons

The time-resolved secondary emission of resonantly created excitons in GaAs quantum wells is studied using femtosecond up-conversion spectroscopy. The behaviour of the rise and decay of the secondary emission and reflectivity in quantum wells is strongly dependent upon the disorder at the interfaces, the exciton density and the temperature. In the case of low densities and temperatures the emission is independent of the exciton density and rises quadratically in time, in excellent agreement with recent theory for Rayleigh scattering from two-dimensional excitons subjected to disorder. These rise times are compared directly with times measured by time-integrated four-wave mixing (FWM). The comparison of the dynamics displayed in time-resolved secondary radiation and time-integrated FWM provide a clear understanding of the coherence properties of QW excitons in the first few picoseconds after excitation. High-contrast oscillations that are due to quantum beats between the heavy- and light-hole 1s-states are seen. The visibility decay at very low densities is long ps and is related to the action of potential fluctuations on the scattering of heavy-hole and light-hole excitons.     

Full-field characterization of femtosecond pulses by spectrum and cross-correlation measurements

We present a practical and accurate technique for retrieving the amplitude and the phase of ultrashort pulses from a nonlinear (second-order) intensity cross correlation and the spectrum that overcomes shortcomings of previous attempts. We apply the algorithm to theoretical and experimental data and compare it with frequency-resolved optical gating.     

Second-harmonic generation frequency-resolved optical gating analysis of low-intensity shaped femtosecond pulses at 1.55 mum

We illustrate observation and characterization of medium- and low-intensity shaped ultrashort pulses at lambda=1.55mum through single-shot geometry (multishot-average) second-harmonic generation-frequency-resolved optical gating. The pulses are shaped by amplitude filters in the Fourier plane of a compact folded shaper. Sensitivity to pulses with energies of less than 20 pJ and high dynamic range is reported for this configuration. Application of this method to the propagation of ~170-fs pulses through a 50-m fiber link is also illustrated.     

Sub-megabar Mössbauer studies using diamond anvil cells

The development and the use of the diamond anvil cell for Mössbauer Spectroscopy (MS) to pressures nearing 100 GPa are discussed. Three types of cells and their typical performance are given. Pressure calibration, hydrostatic media, gasketing, collimation, -ray absorption, and sample size for MS are reviewed. New MS results showing hysteresis in the room temperature high pressure transition in iron and showing the rapid rise ofT _N in NiI₂ with pressure are presented.     

Extended magnetic reconnection across the dayside magnetopause

The extent of where magnetic reconnection (MR), the dominant process responsible for energy and plasma transport into the magnetosphere, operates across Earth's dayside magnetopause has previously been only indirectly shown by observations. We report the first direct evidence of X-line structure resulting from the operation of MR at each of two widely separated locations along the tilted, subsolar line of maximum current on Earth's magnetopause, confirming the operation of MR at two or more sites across the extended region where MR is expected to occur. The evidence results from in-situ observations of the associated ion and electron plasma distributions, present within each magnetic X-line structure, taken by two spacecraft passing through the active MR regions simultaneously.     

Photoexcited carrier relaxation dynamics in pentacene probed by ultrafast optical spectroscopy: Influence of morphology on relaxation processes

We present a comparative study of ultrafast photoexcited state relaxation in pentacene single crystals and in pure and C₆₀-doped pentacene films using optical pump-probe spectroscopy. The photoinduced absorption spectra in pentacene crystals is consistent with a dominant singlet-triplet fission decay channel for above-gap excitation. This decay channel is suppressed in thin films and even further suppressed by electron trapping in C₆₀-doped films. Thus we show that suppression of triplet state production, which is necessary for free carrier formation and thus photovoltaic and photodiode performance, is controllable via sample morphology.