Intersubband transitions in nonpolar GaN/Al(Ga)N heterostructures in the short and mid-wavelength infrared regions

This paper assesses nonpolar m- and a-plane GaN/Al(Ga)N multi-quantum-wells grown on bulk GaN for intersubband optoelectronics in the short- and mid-wavelength infrared ranges. The characterization results are compared to those for reference samples grown on the polar c-plane, and are verified by self-consistent Schr\"odinger-Poisson calculations. The best results in terms of mosaicity, surface roughness, photoluminescence linewidth and intensity, as well as intersubband absorption are obtained from m-plane structures, which display room-temperature intersubband absorption in the range from 1.5 to 2.9 um. Based on these results, a series of m-plane GaN/AlGaN multi-quantum-wells were designed to determine the accessible spectral range in the mid-infrared. These samples exhibit tunable room-temperature intersubband absorption from 4.0 to 5.8 um, the long-wavelength limit being set by the absorption associated with the second order of the Reststrahlen band in the GaN substrates

Case 10 : Middlesex-London’s Public Health Emergency: HIV in People Who Inject Drugs

Middlesex-London is experiencing an alarming rise of new HIV cases in people who inject drugs (PWID). Despite a demonstrably successful harm reduction program and primary care effort, the rapid increase in HIV remains. To help reduce the incidence of HIV in PWID, in association with Regional HIV/AIDS Connection (RHAC), My Sister’s Place, and the Middlesex-London Health Unit (MLHU), the Counterpoint Needle and Syringe Program in Middlesex-London distributed over three million needles in 2016. Nevertheless, healthcare workers continue to diagnose PWID with HIV and other infections. Of those needles distributed, only 1,895,798 were recovered through these organizations and, thus, improperly discarded needles have been spotted across the city on multiple occasions. PWID in Middlesex-London face significant barriers when accessing care and support. Barriers, including, but not limited to, psychosocial (i.e., stigma, social support), structural (i.e., housing, treatment access, poverty), and institutional factors (i.e., patient-physician relationship), can hinder PWID from accessing adequate healthcare and support services. With an aim to address some of the barriers faced by PWID, the Middlesex-London Health Unit has established an HIV Leadership Team that works collaboratively with key system partners in the field of HIV treatment and support, substance use, and support for people who experience homelessness. This case demonstrates the impact of social determinants of health such as poverty, homelessness, and inequalities in PWID’s health, well-being, morbidity and mortality patterns, as well as their access to care. This case also highlights the importance of recognizing the influence of social determinants of health in the planning, implementation, and evaluation processes of public health programs to ensure that interventions are effective, cost-effective, and equitable

Dynamic images to address conceptual nodes about mechanical waves: Example materials and preliminary results of the experimentation of the teacher training module IMAGONDE

In the framework of the 2002-03 project “Fisica per la Formazione Culturale - FORMazione Insegnanti” funded by Italy ministry of Education, a set of training materials, focused on mechanical waves, has been developed. The core of the materials is represented by animated images purposely designed in order to: 1) address intrinsically dynamic aspects of one-dimensional impulses/waves propagation on a string; 2) have the trainees reflect upon students’ difficulties in reading/interpreting static images (as the ones which are featured in common textbooks) and animations. In this paper we discuss example materials concerning transversal impulses on strings to address conceptual nodes such as: 1) configuration of the string at a given time and its abstract representation; 2) displacement vs. time graph of a string element and its abstract representation; 3) relationships between the two abstract representations; 4) modelization of mechanical wave propagation in one dimension. Moreover the results of the experimentation of the training materials in the framework of the Post Graduate School to Became Physics Teacher in Secondary Schools are presented and commented

Design of polarization-insensitive superconducting single photon detectors with high-index dielectrics

In this paper, the design of superconducting-nanowire single-photon detectors which are insensitive to the polarization of the incident light is investigated. By using high-refractive-index dielectrics, the index mismatch between the nanowire and the surrounding media is reduced. This enhances the absorption of light with electric field vector perpendicular to the nanowire segments, which is generally hindered in this kind of detectors. Building on this principle and focusing on NbTiN nanowire devices, we present several easy-to-realize cavity architectures which allow high absorption efficiency (in excess of 90%) and polarization insensitivity simultaneously. Designs based on ultranarrow nanowires, for which the polarization sensitivity is much more marked, are also presented. Finally, we briefly discuss the specific advantages of this approach in the case of WSi or MoSi nanowires