On the Photorefractive Gunn Effect

We present and numerically solve a model of the photorefractive Gunn effect. We find that high field domains can be triggered by phase-locked interference fringes, as it has been recently predicted on the basis of linear stability considerations. Since the Gunn effect is intrinsically nonlinear, we find that such considerations give at best order-of-magnitude estimations of the parameters critical to the photorefractive Gunn effect. The response of the system is much more complex including multiple wave shedding from the injecting contact, wave suppression and chaos with spatial structure.Comment: Revtex, 8 pag., 4 fig. (jpg), submit to Physical Review

Theory and simulation of the nematic zenithal anchoring coefficient

Combining molecular simulation, Onsager theory and the elastic description of nematic liquid crystals, we study the dependence of the nematic liquid crystal elastic constants and the zenithal surface anchoring coefficient on the value of the bulk order parameter

Experimental studies of light-microwave field interaction and nonequilibrium carrier transport in GaAs

Contactless nonlinear optics and microwave techniques are combined to study nonequilibrium carrier transport and photoelectric properties of GaAs crystals in electric fields. Peculiarities of complex diffusion-drift processes of photoexcited carrier plasma under microwave heating.and fast transients of carrier transport in space-charge internal electric field are analysed by measuring orientational, temporal and field dependences of light diffraction on light-induced transient grating

Laser-induced gratings and hot-carrier dynamics in III-V semiconductors

International audienc

Nondestructive characterisation of MOVPE-grown CdTe and ZnTe epilayers by picosecond and nanosecond "excite-probe" techniques

Photogeneration of non-equilibrium carriers by short laser pulses and measurements of their dynamics by different contactless techniques were used to characterize II-VI heterostructures. Quite small surface recombination rates were found for ZnTe and CdTe epilayers, whilst bulk recombination in these materials was rather efficient. For CdTe, the carrier lifetime ranges in the 250-300 ps interval, the surface recombination velocity being about 10(4) cm/s

Combining diuretic response and hemoconcentration to predict rehospitalization after admission for acute heart failure

Background—Both diuretic response and hemoconcentration are indicators of decongestion and have individually been found to predict rehospitalization after admission for acute heart failure (HF). This study examines the value of combining diuretic response and hemoconcentration to better predict patients at low risk for rehospitalization after admission for acute HF. Methods and Results—Diuretic response (defined as weight change per 40 mg of furosemide on day 4 after admission) and hemoconcentration (change in hemoglobin at discharge or day 7) were tested both individually and combined to predict the risk of HF and cardiovascular rehospitalization 60 days after hospitalization for acute HF. Analyses were performed in 1180 patients enrolled in the Placebo-Controlled Randomized Study of the Selective Adenosine Receptor Antagonist Rolofylline for Patients Hospitalized With Acute Decompensated Heart Failure and Volume Overload to Assess Treatment Effect on Congestion and Renal Function (PROTECT) trial and validated in 1776 patients enrolled in the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study With Tolvaptan (EVEREST) trial. Poor diuretic response was associated with low systolic blood pressure, high blood urea nitrogen, and history of coronary revascularization in both data sets (all P<0.05). Hemoconcentration was mainly associated with better renal function (P<0.05). Patients who displayed both favorable diuretic response and hemoconcentration had a markedly lower risk of rehospitalization for HF in PROTECT (multivariable HR, 0.41; 95% CI, 0.24 to 0.70; P<0.001) compared with all other patients. This finding was confirmed in EVEREST (multivariable HR, 0.52; 95% CI, 0.33 to 0.82; P=0.004) for patients with favorable diuretic response and hemoconcentration compared with all other patients. Conclusions—Combining 2 indicators of decongestion, hemoconcentration and diuretic response improves risk prediction for early rehospitalization after an admission for acute HF and may provide clinicians with an easily accessible tool to identify low-risk patients