Electrical isolation and transparency in ion-irradiated p-InGaP/GaAs/InGaAs structures

He+-ion irradiation was applied for electrical isolation of p-In0.49Ga0.51P in InGaP/GaAs/InGaAs structures. Sheet resistance of approximately 1x10(6) Omega/square was achieved with doses above 1x10(13) cm(-2) at 100 keV. Thermal stability of isolation was maintained for annealing temperatures up to 500 degreesC. Photoluminescence results show that InGaP transparency to InGaAs/GaAs quantum-well emission is closely related to sheet resistance changes in the irradiated structure. (C) 2000 American Institute of Physics. [S0021- 8979(01)02401-X].88127354735

In0.49Ga0.51P growth on pre-patterned GaAs substrates by chemical beam epitaxy

We present a study on the growth of lattice-matched InGaP on patterned GaAs substrates by chemical beam epitaxy. An experimental analysis of the growth on planes [100] and [111]A as a function of growth temperature and pattern dimension is presented. A simple surface kinetics model is proposed allowing the determination of diffusion length, incorporation time and free species lifetime on both planes. Incorporation on planes [111]A reduces with increase in temperature and there is indication of a relationship between evaporation time and nucleation sites on [111]A planes (C) 1998 Elsevier Science B.V. All rights reserved.193451051

Spatial composition dependence in InGaP growth on pre-patterned GaAs substrates by chemical beam epitaxy

We have investigated the spatial composition variation in InGaP layers grown by chemical beam epitaxy (CBE) on pre-patterned substrates. At growth temperature of 540 degrees C, no difference between In and Ga growth properties is observed. At 500 degrees C, we observe the onset of new crystalline planes on the side walls of the pre-patterned structure. Finally, we show how these planes are related to a measured strong spatial composition variation. (C) 1999 Elsevier Science B.V. All rights reserved.203331732

Strong spatial beryllium doping selectivity on InGaP layers grown on pre-patterned GaAs substrates by chemical beam epitaxy

We present an investigation of beryllium doping selectivity in InGaP layers grown by chemical beam epitaxy on pre-patterned substrates. We observed a resistivity of 3.1 X 10(-2) and 4.5 x 10(-2) Omega cm for (1 1 1)A planes with the growth at 500degreesC and 540degreesC, respectively. The layers on (0 0 1) planes show a resistivity of 8.9 x 10(-1) Omega cm with the growth at 500degreesC, being essentially undoped with the growth at 540degreesC (.) We show how this strong doping selectivity can be explained by Be3P2 cluster formation growth, which depends on growth temperature and planar crystalline structure. (C) 2004 Elsevier B.V. All rights reserved.266442943

Lack of tax diversity for tropical spastic paraparesis/human T-cell lymphotropic virus type 1 (HTLV-I) associated myelopathy development in HTLV-I-infected subjects in São Paulo, Brazil

The product of human T-cell lymphotropic virus type 1 (HTLV-1) tax gene has a transactivating effect of the viral and cellular gene expression. Genetic variations in this gene have been correlated with differences in clinical outcomes. Based upon its diversity, two closely related substrains, namely tax A and tax B, have been described. The tax A substrain has been found at a higher frequency among human T-cell leukemia virus type 1 (TSP/HAM) patients than among healthy HTLV-I-infected asymptomatic subjects in Japan. In this study, we determined the distribution of tax substrains in HTLV-I-infected subjects in the city of São Paulo, Brazil. Using the ACCII restriction enzyme site, we detected only tax A substrain from 48 TSP/HAM patients and 28 healthy HTLV-I carriers. The sequenced tax genes from nine TSP/HAM patients and five asymptomatic HTLV-I carriers showed a similar pattern of mutation, which characterizes tax A. Our results indicate that HTLV-I tax subtypes have no significant influences on TSP/HAM disease progression. Furthermore, monophyletic introduction of HTLV-I to Brazil probably occurred during the African slave trade many years ago

Skin and Digital–The 2024 Narrative

The global burden of skin diseases affects over 3 billion individuals, posing important public health challenges worldwide, with profound impacts in both high-income and low-income and middle-income countries. These challenges are exacerbated by widespread disparities in access to dermatologic care and the prevalence of misinformation. This article, derived from the Skin and Digital Summit at the International Master Course on Aging Science critically evaluates how digital technologies such as artificial intelligence, teledermatology, and large language models can bridge these access gaps. It explores practical applications and case studies demonstrating the impact of these technologies in various settings, with a particular focus on adapting solutions to meet the diverse needs of low-income and middle-income countries. In addition, the narrative highlights the ongoing conversation within the dermatologic community about the role of digital advances in health care, emphasizing that this discussion is dynamic and the one that is continuously evolving. Dermatologists play an essential role in this transition, integrating digital tools into mainstream care to complement a patient-centered, culturally sensitive approach. The article advocates for a globally coordinated digital response that not only addresses current disparities in skin health care but also promotes equitable access to digital health resources, making dermatologic care more representative of all skin types and accessible worldwide