We have investigated the photoluminescence of single and multiple layers of Ge/Si self-assembled quantum dots as a function of the excitation power density. We show that the photoluminescence of the quantum dots is strongly dependent on the pump excitation power. The photoluminescence broadens and is blueshifted by as much as 80 meV as the power excitation density increases. Meanwhile, the photoluminescence associated with the two-dimensional wetting layers exhibits only a weak dependence on the pump excitation power. This significant blueshift is interpreted in terms of state filling and recombination from the confined excited hole states in the dots. The photoluminescence data are correlated to the density of states as calculated by solving the three-dimensional Schrödinger equation in these islands with a lateral size of the order of 100 nm.

Complex regional pain syndrome (CRPS) is a pathologic condition in which the painful experience is disproportionate in time and intensity in comparison with the inciting event. At present, the pathophysiology of CRPS is not well understood. Several studies have indicated that cortical reorganization plays a role in the persistence of the symptoms. A new promising approach, graded motor imagery (GMI), seems to be effective, but there are limited data for the CRPS-1 upper extremity population. The aim of this study was to demonstrate the effectiveness of a modified GMI (mGMI) protocol based on the work of Moseley to reduce pain and enhance functional capacities for a population with nonchronic CRPS-1 of the upper extremity. The following outcome measures were used to assess the clinical effectiveness: pain (short form of the McGill Pain Questionnaire), grip force (Martin vigorimeter), perception of upper extremity function (Disabilities of the Arm, Shoulder and Hand Questionnaire), and patient's global impression of change. All outcomes at T4 were compared with the baseline data (T0) using the Mann-Whitney test and the χ test (nonparametric tests). Seven patients were recruited for the study. At the end of the mGMI (T4), we obtained significant results for the decrease in the pain experienced in the last 7 days (visual analog scale; P=0.046), improvement in the affected extremity grip force (P=0.042), and the patient's global impression of change (P=0.015). However, the data of the perception of upper extremity function (Disabilities of the Arm, Shoulder and Hand Questionnaire) were not clinically or statistically significant. Our results indicate that this mGMI protocol seems to be a promising therapeutic modality to reduce pain. However, more investigations are needed to determine whether mGMI has a significant impact on upper extremity function.