Skip to main content Accessibility help

We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.

Close cookie message
×
Home
  • Home

Refine search

Refine search

Access:
Content type:
Publication date:
Apply
Subject: Show more
Journals Show more
Publishers: Show more
Societies Show more
Series: Show more
Collections: Show more

Actions for selected content:

Select all | Deselect all
  • View selected items
  • Export citations
  • Download PDF (zip)
  • Send to Kindle
  • Send to Dropbox
  • Send to Google Drive

Save Search

You can save your searches here and later view and run them again in "My saved searches".

Please provide a title, maximum of 40 characters.
Cancel
×

101 results

Page 1 of 6

  • Cosmology, astrobiology and the RNA world: just add quintessential water
  • Keith Johnson
  • Journal: International Journal of Astrobiology , First View
  • Published online by Cambridge University Press: 07 January 2021, pp. 1-14
  • View abstract

    Laboratory generation of water nanoclusters from amorphous ice and strong terahertz (THz) radiation from water nanoclusters ejected from water vapour into a vacuum suggest the possibility of water nanoclusters ejected into interstellar space from abundant amorphous ice-coated cosmic dust produced by supernovae explosions. Water nanoclusters (section ‘Water nanoclusters’) offer a hypothetical scenario connecting major mysteries of our Universe: dark matter (section ‘Baryonic dark matter’), dark energy (section ‘Dark energy’), cosmology (section ‘Cosmology’), astrobiology (section ‘Astrobiology’) and the RNA world (section ‘The RNA world’) as the origin of life on Earth and habitable exoplanets. Despite their expected low density in space compared to hydrogen, their quantum-entangled diffuse Rydberg electronic states make cosmic water nanoclusters a candidate for baryonic dark matter that can also absorb, via the microscopic dynamical Casimir effect, the virtual photons of zero-point-energy vacuum fluctuations above the nanocluster cut-off vibrational frequencies, leaving only vacuum fluctuations below these frequencies to be gravitationally active, thus leading to a possible common origin of dark matter and dark energy. This picture includes novel explanations of the small cosmological constant, the coincidence of energy and matter densities, possible contributions of the red-shifted THz radiation from cosmic water nanoclusters at redshift z ≅ 10 to the cosmic microwave background (CMB) spectrum, the Hubble constant crisis, the role of water as a known coolant for rapid early star formation and ultimately, how life may have originated from RNA protocells on Earth and exoplanets and moons in the habitable zones of developed solar systems. Together, they lead to a cyclic universe cosmology – based on the proposed equivalence of cosmic water nanoclusters to a quintessence scalar field – instead of a multiverse based on cosmic inflation theory. Recent CMB birefringence measurements may support quintessence. Finally, from the quantum chemistry of water nanoclusters interacting with prebiotic organic molecules, amino acids and RNA protocells on early Earth and habitable exoplanets, this scenario is consistent with the anthropic principle that our Universe must have those properties which allow life, as we know it – based on water, to develop at the present stage of its history.

  • In Memoriam John J. Ohala (1941–2020)
  • Keith Johnson
  • Journal: Journal of the International Phonetic Association / Volume 50 / Issue 3 / December 2020
  • Published online by Cambridge University Press: 16 December 2020, pp. 452-455
  • Print publication: December 2020
    • Article
    • Access
    • PDF
    • HTML
    • Export citation
  • Identifying Sensitive Measures of Cognitive Decline at Different Clinical Stages of Alzheimer’s Disease
  • Roos J. Jutten, Sietske A.M. Sikkes, Rebecca E. Amariglio, Rachel F. Buckley, Michael J. Properzi, Gad A. Marshall, Dorene M. Rentz, Keith A. Johnson, Charlotte E. Teunissen, Bart N.M. Van Berckel, Wiesje M. Van der Flier, Philip Scheltens, Reisa A. Sperling, Kathryn V. Papp, for the Alzheimer Disease Neuroimaging Initiative, National Alzheimer’s Coordinating Center, the Harvard Aging Brain Study, and the Alzheimer Dementia Cohort
  • Journal: Journal of the International Neuropsychological Society , First View
  • Published online by Cambridge University Press: 13 October 2020, pp. 1-13
    • Article
    • Access
    • Open access
    • PDF
    • HTML
    • Export citation
  • View abstract
    Objective:

    Alzheimer’s disease (AD) studies are increasingly targeting earlier (pre)clinical populations, in which the expected degree of observable cognitive decline over a certain time interval is reduced as compared to the dementia stage. Consequently, endpoints to capture early cognitive changes require refinement. We aimed to determine the sensitivity to decline of widely applied neuropsychological tests at different clinical stages of AD as outlined in the National Institute on Aging – Alzheimer’s Association (NIA-AA) research framework.

    Method:

    Amyloid-positive individuals (as determined by positron emission tomography or cerebrospinal fluid) with longitudinal neuropsychological assessments available were included from four well-defined study cohorts and subsequently classified among the NIA-AA stages. For each stage, we investigated the sensitivity to decline of 17 individual neuropsychological tests using linear mixed models.

    Results:

    1103 participants (age = 70.54 ± 8.7, 47% female) were included: n = 120 Stage 1, n = 206 Stage 2, n = 467 Stage 3 and n = 309 Stage 4. Neuropsychological tests were differentially sensitive to decline across stages. For example, Category Fluency captured significant 1-year decline as early as Stage 1 (β = −.58, p < .001). Word List Delayed Recall (β = −.22, p < .05) and Trail Making Test (β = 6.2, p < .05) became sensitive to 1-year decline in Stage 2, whereas the Mini-Mental State Examination did not capture 1-year decline until Stage 3 (β = −1.13, p < .001) and 4 (β = −2.23, p < .001).

    Conclusions:

    We demonstrated that commonly used neuropsychological tests differ in their ability to capture decline depending on clinical stage within the AD continuum (preclinical to dementia). This implies that stage-specific cognitive endpoints are needed to accurately assess disease progression and increase the chance of successful treatment evaluation in AD.

  • Didn't hear that coming: Effects of withholding phonetic cues to code-switching
  • Alice Shen, Susanne Gahl, Keith Johnson
  • Journal: Bilingualism: Language and Cognition / Volume 23 / Issue 5 / November 2020
  • Published online by Cambridge University Press: 31 January 2020, pp. 1020-1031
  • Print publication: November 2020
    • Article
    • Access
    • Open access
    • PDF
    • HTML
    • Export citation
  • View abstract

    Code-switching has been found to incur a processing cost in auditory comprehension. However, listeners may have access to anticipatory phonetic cues to code-switches (Piccinini & Garellek, 2014; Fricke et al., 2016), thus mitigating switch cost. We investigated effects of withholding anticipatory phonetic cues on code-switched word recognition by splicing English-to-Mandarin code-switches into unilingual English sentences. In a concept monitoring experiment, Mandarin–English bilinguals took longer to recognize code-switches, suggesting a switch cost. In an eye tracking experiment, the average proportion of all participants' looks to pictures corresponding to sentence-medial code-switches decreased when cues were withheld. Acoustic analysis of stimuli revealed tone-specific pitch contours before English-to-Mandarin code-switches, consistent with previous work on tonal coarticulation. We conclude that withholding anticipatory phonetic cues can negatively affect code-switched recognition: therefore, bilingual listeners use phonetic cues in processing code-switches under normal conditions. We discuss the implications of tonal coarticulation for mechanisms underlying phonetic cues to code-switching.

  • The influence of demographic factors on subjective cognitive concerns and beta-amyloid
  • Sarah L. Aghjayan, Rachel F. Buckley, Patrizia Vannini, Dorene M. Rentz, Jonathan D. Jackson, Reisa A. Sperling, Keith A. Johnson, Rebecca E. Amariglio
  • Journal: International Psychogeriatrics / Volume 29 / Issue 4 / April 2017
  • Published online by Cambridge University Press: 11 October 2016, pp. 645-652
  • Print publication: April 2017
  • View abstract
    Background:

    Converging evidence suggests that subjective cognitive concerns (SCC) are associated with biomarker evidence of Alzheimer's disease (AD) prior to objective clinical impairment. However, the sensitivity of SCC reports in early AD may be biased by demographic factors. Here, we sought to investigate whether age, education, and sex influence the relationship between SCC and amyloid (Aβ) burden.

    Methods:

    In this cross-sectional study, we examined 252 clinically normal (CN) individuals (57.7% females) enrolled in the Harvard Aging Brain Study, ages 63–90 years (mean 73.7±6) with 6–20 years of education (mean 15.8±3). SCC was assessed as a composite score comprising three questionnaires. Cortical Aβ burden was assessed with Pittsburgh compound B positron emission tomography imaging. A series of linear regression models assessed the potential modifying role of demographic variables with respect to Aβ burden and SCC. A post-hoc mediation model was implemented to further understand the relationship between Aβ burden and SCC via their relationship with education.

    Results:

    Age (β = −0.84, p = 0.36) and sex (β = −0.55, p = 0.22) did not modify the relationship between SCC and Aβ burden. Fewer years of education was correlated with greater SCC (r = −0.12, p = 0.05), but the relationship between Aβ burden and SCC was stronger in those with more education (β = 1.16, p < 0.05). A partial mediation effect was found of Aβ burden on SCC via education (b = −0.12, 95% CI [−0.31, −0.02]).

    Conclusions:

    These findings suggest that the association between SCC and Aβ burden becomes stronger with greater educational attainment. Thus, SCC may be of particular importance in highly educated CN individuals harboring amyloid pathology.

  • 18 - Surveying political extremists
  • Edited by Roger Tourangeau, Brad Edwards, Timothy P. Johnson, University of Illinois, Chicago, Kirk M. Wolter, University of Chicago, Nancy Bates
  • Book: Hard-to-Survey Populations
  • Published online: 05 September 2014
  • Print publication: 28 August 2014, pp 379-398
  • View extract

    Summary

    Introduction

    Collecting survey data from political extremists (or persons affiliated with extremist political groups) presents a set of unique challenges. Many of these challenges are faced by researchers investigating other hard-to-survey populations (e.g., political extremists are rare, difficult to identify, and under some circumstances may be reluctant to participate in research), but not in combination as they are with this particular group of potential respondents. In this chapter, we first develop a working definition of political extremism. We next provide an overview of the challenges faced by researchers who want to study political extremism and examine some of the strategies employed by investigators when attempting to study political extremists. Finally, we examine some of the ethical issues involved in conducting survey research with persons who espouse extremist political ideologies.

    Defining “political extremism”

    “Political extremists” have multiple self-identities and it is a challenge to develop an operational definition that adequately covers this diversity. In practice, political extremism at the individual level has been defined in two primary ways. First, it is often viewed in terms of the behaviors associated with it. For example, van Es and Koenig (1976) see political extremism as the use of coercion to force change in political institutions and authority. Political extremists, then, have sometimes been defined as those who engage in these behaviors or who advocate them. Secondly, others have defined political extremists in terms of the attitudes or beliefs that they hold. In his Dictionary of Political Thought, Scruton (1982) suggests that political extremism involves pushing ideas to their limits, intolerance of competing viewpoints, confronting and eliminating opposition, and demonstrating a disregard for the rights of others. Similarly, Midlarsky (2011, p. 7) provides a definition of political extremism that integrates both beliefs and behaviors, which he suggests is:

    the will power by a social movement in the service of a political program typically at variance with that supported by existing state authorities, and for which individual liberties are to be curtailed in the name of collective goals, including the mass murder of those who would actually or potentially disagree with that program.

  • 1 - Introduction
  • Edited by James P. Hawley, St Mary's College, California, Andreas G. F. Hoepner, Keith L. Johnson, University of Wisconsin, Madison, Joakim Sandberg, Edward J. Waitzer, York University, Toronto
  • Book: Cambridge Handbook of Institutional Investment and Fiduciary Duty
  • Published online: 05 April 2014
  • Print publication: 10 April 2014, pp 1-6
  • View extract

    Summary

    Introduction

    This Handbook responds to the evolution in the ownership of companies and financial assets over the past thirty to fifty years. It also is concerned with the more recent widespread failure of pensions and other long-term savings vehicles to deliver on sustainable financial security goals for the individuals whose monies they are investing.

    The volume highlights important changes in the landscape of finance, especially with regard to institutional investors: those large financial institutions entrusted to manage most of our savings, pensions, retirement funds, insurance assets and national wealth reserves. It primarily focuses on the changing legal understanding of the role and purpose of these institutions in many countries. This includes recognition of the influence that collective investment practices of institutional investors have on society and the greater economy, as well as the corresponding influence that economic health and social stability have on the sustainability of institutional investors’ performance and their ability to succeed in meeting long-term goals for the beneficiaries who depend on them and who collectively constitute the societies in which they exist. The Handbook is also a testament to the rapidly evolving nature of academic research and public policy discourse concerning institutional investment and financial markets.

Page 1 of 6