Thermal Activation of Anti-Stokes Photoluminescence in CsPbBr Perovskite Nanocrystals: The Role of Surface Polaron States.

Optically driven cooling of a material, or optical refrigeration, is possible when optical up-conversion via anti-Stokes photoluminescence (ASPL) is achieved with near-unity quantum yield. The recent demonstration of optical cooling of CsPbBr perovskite nanocrystals (NCs) has provided a path forward in the development of semiconductor-based optical refrigeration strategies. However, the mechanism of ASPL in CsPbBr NCs is not yet settled, and the prospects for cooling technologies strongly depend on details of the mechanism.

Probing Oxidation-Driven Amorphized Surfaces in a Ta(110) Film for Superconducting Qubit.

Recent advances in superconducting qubit technology have led to significant progress in quantum computing, but the challenge of achieving a long coherence time remains. Despite the excellent lifetime performance that tantalum (Ta) based qubits have demonstrated to date, the majority of superconducting qubit systems, including Ta-based qubits, are generally believed to have uncontrolled surface oxidation as the primary source of the two-level system loss in two-dimensional transmon qubits. Therefore, atomic-scale insight into the surface oxidation process is needed to make progress toward a practical quantum processor.

Modeling the potential benefit of an over-the-counter progestin-only pill in preventing unintended pregnancies in the U.S.

Objectives: To develop a model to estimate the possible impact of use of an over-the-counter (OTC) progestin-only pill (POP) on the number of unintended pregnancies in the United States.

Study Design: Using typical use failure rates (7% for POPs), we compared the expected number of unintended pregnancies for two theoretical cohorts of 100,000 women: one which purchased and used an OTC POP exclusively for contraception, the other using contraceptive methods at proportions obtained from an actual-use clinical trial simulating OTC use of norgestrel 0.075 mg (including 35% using no method and only 19% using hormonal contraception or long-acting contraceptives).