Is Vasomotion in Cerebral Arteries Impaired in Alzheimer’s Disease?

A substantial body of evidence supports the hypothesis of a vascular component in the pathogenesis of Alzheimer’s disease (AD). Cerebral hypoperfusion and blood-brain barrier dysfunction have been indicated as key elements of this pathway. Cerebral amyloid angiopathy (CAA) is a cerebrovascular disorder, frequent in AD, characterized by the accumulation of amyloid-β (Aβ) peptide in cerebral blood vessel walls. CAA is associated with loss of vascular integrity, resulting in impaired regulation of cerebral circulation, and increased susceptibility to cerebral ischemia, microhemorrhages, and white matter damage. Vasomotion— the spontaneous rhythmic modulation of arterial diameter, typically observed in arteries/arterioles in various vascular beds including the brain— is thought to participate in tissue perfusion and oxygen delivery regulation. Vasomotion is impaired in adverse conditions such as hypoperfusion and hypoxia. The perivascular and glymphatic pathways of Aβ clearance are thought to be driven by the systolic pulse. Vasomotion produces diameter changes of comparable amplitude, however at lower rates, and could contribute to these mechanisms of Aβ clearance. In spite of potential clinical interest, studies addressing cerebral vasomotion in the context of AD/CAA are limited. This study reviews the current literature on vasomotion, and hypothesizes potential paths implicating impaired cerebral vasomotion in AD/CAA. Aβ and oxidative stress cause vascular tone dysregulation through direct effects on vascular cells, and indirect effects mediated by impaired neurovascular coupling. Vascular tone dysregulation is further aggravated by cholinergic deficit and results in depressed cerebrovascular reactivity and (possibly) impaired vasomotion, aggravating regional hypoperfusion and promoting further Aβ and oxidative stress accumulation

Television White Spaces: Assessing TVWS for Rural Broadband Access

Detailed findings from a trial deployment of technologies used to provision high-speed Internet access over license-exempt airwaves are now available from the University of New Hampshire Broadband Center of Excellence

Search in Service of Choice

Understanding consumer search behavior is crucial for businesses and policymakers aiming to effectively engage with consumers through product offerings and interventions. Consumer search remains a significant research topic across disciplines such as marketing, economics, and psychology. However, differences in theoretical assumptions and methodological approaches across these fields pose challenges that hinder interdisciplinary knowledge and theory integration. Theoretical assumptions about search range from randomness in relation to choice value to search being influenced by cognitive and visual factors. Methodological approaches vary from direct observations, like eye tracking, to inferences from observed choices. To address the lack of consensus and facilitate scientific progress, we propose a framework for integrating theoretical and methodological approaches across disciplines. We review six prominent theoretical models, each with distinct terminologies and focus areas. For each model, we review its background, aims, core assumptions, and provide illustrative examples. Our contribution is a synthesis initiative that resolves terminological differences and outlines a path toward theory integration. We discuss how our framework can guide future research and foster a more comprehensive understanding of consumer search and choice