Spin-dependent transport in metal/semiconductor tunnel junctions

This paper describes a model as well as experiments on spin-polarized tunnelling with the aid of optical spin orientation. This involves tunnel junctions between a magnetic material and gallium arsenide (GaAs), where the latter is optically excited with circularly polarized light in order to generate spin-polarized carriers. A transport model is presented that takes account of carrier capture in the semiconductor surface states, and describes the semiconductor surface in terms of a spin-dependent energy distribution function. The so-called surface spin-splitting can be calculated from the balance of the polarized electron and hole flow in the semiconductor subsurface region, the polarized tunnelling current across the tunnel barrier between the magnetic material and the semiconductor surface, and the spin relaxation at the semiconductor surface. Measurements are presented of the circular-polarization-dependent photocurrent (the so-called helicity asymmetry) in thin-film tunnel junctions of Co/Al2O3/GaAs. In the absence of a tunnel barrier, the helicity asymmetry is caused by magneto-optical effects (magnetic circular dichroism). In the case where a tunnel barrier is present, the data cannot be explained by magneto-optical effects alone; the deviations provide evidence that spin-polarized tunnelling due to optical spin orientation occurs. In Co/τ-MnAl/AlAs/GaAs junctions no deviations from the magneto-optical effects are observed, most probably due to the weak spin polarization of τ-MnAl along the tunnelling direction; the latter is corroborated by bandstructure calculations. Finally, the application of photoexcited GaAs for spin-polarized tunnelling in a scanning tunnelling microscope is discussed.

Magnetoplasmonic design rules for active magneto-optics

Light polarization rotators and non-reciprocal optical isolators are essential building blocks in photonics technology. These macroscopic passive devices are commonly based on magneto-optical Faraday and Kerr polarization rotation. Magnetoplasmonics - the combination of magnetism and plasmonics - is a promising route to bring these devices to the nanoscale. We introduce design rules for highly tunable active magnetoplasmonic elements in which we can tailor the amplitude and sign of the Kerr response over a broad spectral range

Immunohistochemistry Analysis of CD44, EGFR, and p16 in Oral Cavity and Oropharyngeal Squamous Cell Carcinoma

Objectives We analyze the relationship between CD44, epidermal growth factor receptor (EGFR), and p16 expression in oral cavity and oropharyngeal cancers in a diverse population. We also describe whether particular patterns of staining are associated with progression-free survival and overall survival. Study Design Prospective study, single-blind to pathologist and laboratory technologist. Setting Hospital based. Subjects and Methods Immunohistochemistry, comprising gross staining and cellular expression, was performed and interpreted in a blinded fashion on 24 lip/oral cavity and 40 oropharyngeal cancer specimens collected between 2007 and 2012 from participants of a larger study. Information on overall survival and progression-free survival was obtained from medical records. Results Nineteen cases were clinically p16 positive, 16 of which were oropharyngeal. Oral cavity lesions were more likely to exhibit strong CD44 membrane staining ( P = .0002). Strong CD44 membrane and strong EGFR membrane and/or cytoplasmic staining were more common in p16-negative cancers ( P = .006). Peripheral/mixed gross p16 staining pattern was associated with worse survival than the universal staining on univariate and multivariate analyses ( P = .006, P = .030). This held true when combining gross and cellular localization for p16. For CD44, universal gross staining demonstrated poorer overall survival compared with the peripheral/mixed group ( P = .039). CD44 peripheral/mixed group alone and when combined with universal p16 demonstrated the best survival on multivariate analysis ( P = .010). Conclusion In a diverse population, systematic analysis applying p16, CD44, and EGFR gross staining and cellular localization on immunohistochemistry demonstrates distinct patterns that may have prognostic potential exceeding current methods. Larger studies are warranted to investigate these findings further

Multi-institutional Comparison of Temporal Bone Models: A Collaboration of the AAO-HNSF 3D-Printed Temporal Bone Working Group

© American Academy of Otolaryngology–Head and Neck Surgery Foundation 2020. Objective: The American Academy of Otolaryngology–Head and Neck Surgery Foundation’s (AAO-HNSF’s) 3D-Printed Temporal Bone Working Group was formed with the goal of sharing information and experience relating to the development of 3D-printed temporal bone models. The group conducted a multi-institutional study to directly compare several recently developed models. Study Design: Expert opinion survey. Setting: Temporal bone laboratory. Methods: The working group convened in 2018. The various methods in which 3D virtual models had been created and printed in physical form were then shared and recorded. This allowed for comparison of the advantages, disadvantages, and costs of each method. In addition, a drilling event was held during the October 2018 AAO-HNSF Annual Meeting. Each model was drilled and evaluated by attending-level working group members using an 15-question Likert scale questionnaire. The models were graded on anatomic accuracy as well as their suitability as a simulation of both cadaveric and operative temporal bone drilling. Results: The models produced for this study demonstrate significant anatomic detail and a likeness to human cadaver specimens for drilling and dissection. Models printed in standard resin material with a stereolithography printer scored highest in the evaluation, though the margin of difference was negligible in several categories. Conclusion: Simulated 3D temporal bones created through a number of printing methods have potential benefit in surgical training, preoperative simulation for challenging otologic cases, and the standardized testing of temporal bone surgical skills