RESUMEN
Carrier relaxation is a key issue in determining the efficiency of semiconductor optoelectronic device operation. Devices incorporating semiconductor quantum dots have the potential to overcome many of the limitations of quantum-well-based devices because of the predicted long quantum-dot excited-state lifetimes. For example, the population inversion required for terahertz laser operation in quantum-well-based devices (quantum-cascade lasers) is fundamentally limited by efficient scattering between the laser levels, which form a continuum in the plane of the quantum well. In this context, semiconductor quantum dots are a highly attractive alternative for terahertz devices, because of their intrinsic discrete energy levels. Here, we present the first measurements, and theoretical description, of the intersublevel carrier relaxation in quantum dots for transition energies in the few terahertz range. Long intradot relaxation times (1.5 ns) are found for level separations of 14 meV (3.4 THz), decreasing very strongly to approximately 2 ps at 30 meV (7 THz), in very good agreement with our microscopic theory of the carrier relaxation process. Our studies pave the way for quantum-dot terahertz device development, providing the fundamental knowledge of carrier relaxation times required for optimum device design.
RESUMEN
Postoperative sore throat occurs in up to 90% of intubated patients and is the most common complaint of patients after endotracheal intubation. A recent study suggested that the use of lidocaine to inflate the endotracheal tube cuff would decrease the incidence of postoperative sore throat. The purpose of this prospective randomized study was to compare the incidence and severity of sore throat after using lidocaine, saline, or air to inflate the endotracheal tube cuff. Variables typically associated with postoperative sore throat, including endotracheal cuff design, endotracheal tube size, intubation technique, laryngoscopy blade, airway placement, suctioning technique, and anesthetic technique, were controlled. The participants were all ASA physical status I, II, or III, female, adult patients undergoing general endotracheal anesthesia for gynecological procedures. The researcher administered the verbal analogue scale, Melzack's Present Pain Intensity Scale of the McGill Pain Questionnaire, to the 75 participants at two intervals, 1 to 3 hours postoperatively and 22 to 25 hours postoperatively, to assess postoperative sore throat. Analysis using the Kruskal-Wallis test suggested that there was no statistical difference in postoperative sore throat among the 3 groups. Lidocaine, saline, and air had similar effects on postoperative sore throat.