A planar end-fire H-plane Substrate Integrated Waveguide (SIW) horn antenna is designed for 60 GHz on-body channel measurements. The proposed antenna radiates with a polarization normal to the human skin, and yet exhibits a low profile. Furthermore, a 6.1 GHz bandwidth (S 11 <-10dB) is achieved, which enables wide-band channel characterization. The antenna has been fabricated and its performance is evaluated in the presence of a skin-equivalent phantom. Its suitability to perform on-body channel measurements is then discussed.
Unawareness of memory deficits is an early manifestation in patients with Alzheimer’s disease (AD). This intriguing behavior constitutes a form of anosognosia and has neural mechanisms that remain largely unknown. Here, we hypothesized that it may result from a failure in the error-monitoring system, which would prevent AD patients from being aware of their own memory impairment. To investigate, we measured event-related potentials (ERPs) evoked by erroneous responses during a memory task in two groups of amyloid positive individuals who had only subjective memory complaints at study entry: those who progressed to AD within the five-year study period (PROG group); and those who remained cognitively normal throughout the study (CTRL group). A significant reduction in the amplitude of the positivity error (Pe), an ERP related to error awareness, was observed in the PROG group at the time of AD diagnosis, in intra-group analysis, as well as when compared with the CTRL group, in inter-group analysis. To our knowledge, the results of this study reveal for the first time the emergence of a failure in the error-monitoring system from the very early stages of AD, strongly suggesting that a neurophysiological impairment in this system may be critical for the lack of awareness of memory deficits that often delays AD diagnosis. Hence, this study further suggests that a reduced Pe amplitude may constitute a potential neural biomarker of prodromal AD.
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