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This research reports on the results of a 5-year study undertaken in the United States to better understand the reasons for novice science teacher retention in school districts and other local educational agencies that have demonstrably high rates of such retention. The primary question investigated in this study was, “In districts that have demonstrated comparatively more successful novice secondary science teacher retention, what are the factors that relate to such retention?” Analysis of state-level school staffing data between 2007-2018 from four U.S. states was used to identify districts with exemplary novice science teacher retention, and focus districts (n=13) were selected for qualitative site visits and case study construction. The proposed paper presents the findings of this cross-case analysis of the 13 cases. Our analysis, informed by the framework of teacher embeddedness, yielded 10 distinct categories of factors that influenced teacher retention across the case study districts, including support from departmental colleagues, school/district-level systems and culture of support, compensation, teacher autonomy and agency, specialness of place, and five other factors. Implications of specific aspects of the findings related to the retention of teachers of color and the role of mentoring and induction are discussed. 

This research reports on the results of a 5-year study undertaken in the United States to better understand the reasons for novice science teacher retention in school districts and other local educational agencies that have demonstrably high rates of such retention. The primary question investigated in this study was, “In districts that have demonstrated comparatively more successful novice science teacher retention, what are the factors that relate to such retention?” Two additional aims were to report on factors that were specific to schools or districts that were identified as “high-need” by the U.S. Department of Education. The second was to focus on the unique factors reported as relevant to the retention of novice science teachers of color. Analysis of state-level school staffing data between 2007-2018 from four U.S. states was used to identify districts with exemplary novice science teacher retention, and focus districts (n=13) were selected for qualitative site visits and case study construction. The proposed paper presents the findings of this cross-case analysis of the 13 cases. Our analysis, informed by the framework of teacher embeddedness, yielded 10 distinct categories of factors that influenced teacher retention across the case study districts: 1) support from departmental colleagues, 2) school/district-level systems and culture of support, 3) compensation, 4) teacher autonomy and agency, 5) specialness of place, 6) resources for teaching, 7) opportunity and agency for professional growth, 8) district and school-level race-consciousness, 9) affordances related to school size, and 10) personal satisfaction & rewards. Implications of specific aspects of the findings related to the retention of teachers of color and the role of mentoring and induction are discussed. 

Abstract Optical frequency combs, featuring evenly spaced spectral lines, have been extensively studied and applied to metrology, signal processing, and sensing. Recently, frequency comb generation has been also extended to MHz frequencies by harnessing nonlinearities in microelectromechanical membranes. However, the generation of frequency combs at radio frequencies (RF) has been less explored, together with their potential application in wireless technologies. In this work, we demonstrate an RF system able to wirelessly and passively generate frequency combs. This circuit, which we name quasi-harmonic tag (qHT), offers a battery-free solution for far-field ranging of unmanned vehicles (UVs) in GPS-denied settings, and it enables a strong immunity to multipath interference, providing better accuracy than other RF approaches to far-field ranging. Here, we discuss the principle of operation, design, implementation, and performance of qHTs used to remotely measure the azimuthal distance of a UV flying in an uncontrolled electromagnetic environment. We show that qHTs can wirelessly generate frequency combs with μWatt-levels of incident power by leveraging the nonlinear interaction between an RF parametric oscillator and a high quality factor piezoelectric microacoustic resonator. Our technique for frequency comb generation opens new avenues for a wide range of RF applications beyond ranging, including timing, computing and sensing. 

Abstract Massive deployments of wireless sensor nodes (WSNs) that continuously detect physical, biological or chemical parameters are needed to truly benefit from the unprecedented possibilities opened by the Internet-of-Things (IoT). Just recently, new sensors with higher sensitivities have been demonstrated by leveraging advanced on-chip designs and microfabrication processes. Yet, WSNs using such sensors require energy to transmit the sensed information. Consequently, they either contain batteries that need to be periodically replaced or energy harvesting circuits whose low efficiencies prevent a frequent and continuous sensing and impact the maximum range of communication. Here, we report a new chip-less and battery-less tag-based WSN that fundamentally breaks any previous paradigm. This WSN, formed by off-the-shelf lumped components on a printed substrate, can sense and transmit information without any need of supplied or harvested DC power, while enabling full-duplex transceiver designs for interrogating nodes rendering them immune to their own self-interference. Also, even though the reported WSN does not require any advanced and expensive manufacturing, its unique parametric dynamical behavior enables extraordinary sensitivities and dynamic ranges that can even surpass those achieved by on-chip sensors. The operation and performance of the first implementation of this new WSN are reported. This device operates in the Ultra-High-Frequency range and is capable to passively and continuously detect temperature changes remotely from an interrogating node.