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Abstract BackgroundUsing remote assessments for Alzheimer's Disease and Related Disorders (ADRD) studies can have advantages, such as providing research opportunities to individuals who might otherwise be excluded due to geographical distances, transportation difficulties, and physical frailty. As studies adopt remote assessment modalities, however, people at highest risk of ADRD may be less likely to use the internet, own electronic devices, and be comfortable with technology utilization. MethodThese analyses included data obtained through the National Alzheimer's Coordinating Center Uniform Data Set from 3,803 participants across 17 Alzheimer's Disease Research Centers in the United States who completed the Technology Access Survey between July 2^nd, 2020 and April 26^th, 2023. Participants were categorized as either White or Other Race or Ethnicity. Mixed effects logistic regression models using generalized estimating equations with random effect for study site were used to examine the association of education, race and ethnicity, and education x Other Race or Ethnicity interaction with (1) device use and (2) device preferences for remote assessments. The analyses were adjusted for age, sex, cognitive status, and study site. Significance was set atp <0.05. ResultDescriptive statistics are shown in Table 1. Participants with more years of education had greater access to the internet across all devices (Table 2). Other Race or Ethnicity participants had lower odds of access to tablet, laptop and desktop computer compared to White participants. There was a significant interaction between Other Race or Ethnicity and education for use of tablet, laptop and desktop computer, where the effect of higher education was greater in Other Race or Ethnicity than White participants. A similar pattern of results was observed for interest in using a smartphone, tablet, laptop or desktop computer to complete parts of their study visit from home (Table 3). ConclusionThese findings suggest that education has a role in racioethnic differences in technological access and preferences. Future ADRD studies utilizing remote assessments should consider these patterns to inform study design and potential selection of populations studied. 

Front-end polarization modulation enables improved polarization measurement stability by modulating the targeted signal above the low-frequency $1/f$ drifts associated with atmospheric and instrumental instabilities and diminishes the impact of instrumental polarization. In this work, we present the design and characterization of a new 60-cm diameter Reflective Half-Wave Plate (RHWP) polarization modulator for the 90 GHz band telescope of the Cosmology Large Angular Scale Surveyor (CLASS) project. The RHWP consists of an array of parallel wires (diameter 50~µm, 175~µm pitch) positioned 0.88~mm from an aluminum mirror. In lab tests, it was confirmed that the wire resonance frequency ($$f_\mathrm{res}$$) profile is consistent with the target, $139$~Hz$$<154$$~Hz in the optically active region (diameter smaller than 150~mm), preventing the wire vibration during operation and reducing the RHWP deformation under the wire tension. The mirror tilt relative to the rotating axis was controlled to be $<15''$, corresponding to an increase in beam width due to beam smearing of < $0.6''$, %a beam smearing amplitude of $<0.6''$, negligible compared to the beam's full-width half-maximum of $36'$. The median and 16/84th percentile of the wire--mirror separation residual was $$0.048^{+0.013}_{-0.014}$$~mm in the optically active region, achieving a modulation efficiency $$\epsilon=96.2_{+0.5}^{-0.4}\%$$ with an estimated bandpass of 34~GHz. The angular velocity of the RHWP was maintained to an accuracy of within 0.005\% at the nominal rotation frequency (2.5~Hz). The RHWP has been successfully integrated into the CLASS 90 GHz telescope and started taking data in June 2024, replacing the previous modulator that has been in operation since June 2018.