Bistability in a magnetic and nonmagnetic double-quantum-well structure mediated by the magnetic phase transition

The hole distribution in a double quantum well (QW) structure consisting of a magnetic and a nonmagnetic semiconductor QW is investigated as a function of temperature, the energy shift between the QWs, and other relevant parameters. When the itinerant holes mediate the ferromagnetic ordering, it is shown that a bistable state can be formed through hole redistribution, resulting in a significant change in the properties of the constituting magnetic QW (i.e., the paramagnetic-ferromagnetic transition). The model calculation also indicates a large window in the system parameter space where the bistability is possible. Hence, this structure could form the basis of a stable memory element that may be scaled down to a few hole regime.Comment: 9 pages, 3 figure

Absorption and transport enhancement by Ag nanoparticle plasmonics for organic optoelectronics

The organic films such as P3HT/PCBM incorporating Ag metal nanoparticles are fabricated and experimentally characterized. Due to the excited surface plasma induced by Ag metal nanoparticles, the absorption of the active organic material layer is increased by around 30%. The broadened absorption spectrum to the 260-650nm wavelength range is also observed from our measurements because of the enhanced scattering cross section by Ag metal nanoparticles. Furthermore, by incorporating Ag nanoparticles into the active layer, the mobility have also been improved. Finite Difference Time Domain (FDTD) simulations confirm the increase in transmission of electromagnetic radiation at visible wavelength. The hopping model is proposed to explain the transport mechanism for the device operations. These observations suggest a variety of approaches for improving the performance of general organic optoelectronic devices

Long-term Impact of Mode of Delivery on Stress Urinary Incontinence and Urgency Urinary Incontinence : A Systematic Review and Meta-analysis

Context: Stress urinary incontinence (SUI) and urgency urinary incontinence (UUI) are associated with physical and psychological morbidity, and large societal costs. The long-term effects of delivery modes on each kind of incontinence remain uncertain. Objective: To investigate the long-term impact of delivery mode on SUI and UUI. Evidence acquisition: We searched Medline, Scopus, CINAHL, and relevant major conference abstracts up to October 31, 2014, including any observational study with adjusted analyses or any randomized trial addressing the association between delivery mode and SUI or UUI >= 1 yr after delivery. Two reviewers extracted data, including incidence/prevalence of SUI and UUI by delivery modes, and assessed risk of bias. Evidence synthesis: Pooled estimates from 15 eligible studies demonstrated an increased risk of SUI after vaginal delivery versus cesarean section (adjusted odds ratio [aOR]: 1.85; 95% confidence interval [CI], 1.56-2.19; I-2 = 57%; risk difference: 8.2%). Metaregression demonstrated a larger effect of vaginal delivery among younger women (p = 0.005). Four studies suggested no difference in the risk of SUI between spontaneous vaginal and instrumental delivery (aOR: 1.11; 95% CI, 0.84-1.45; I-2 = 50%). Eight studies suggested an elevated risk of UUI after vaginal delivery versus cesarean section (aOR: 1.30; 95% CI, 1.02-1.65; I-2 = 37%; risk difference: 2.6%). Conclusions: Compared with cesarean section, vaginal delivery is associated with an almost twofold increase in the risk of long-term SUI, with an absolute increase of 8%, and an effect that is largest in younger women. There is also an increased risk of UUI, with an absolute increase of approximately 3%. Patient summary: In this systematic review we looked for the long-term effects of childbirth on urinary leakage. We found that vaginal delivery is associated with an almost twofold increase in the risk of developing leakage with exertion, compared with cesarean section, with a smaller effect on leakage in association with urgency. (C) 2016 European Association of Urology. Published by Elsevier B.V.Peer reviewe