1496 results
Extremophile hypolithic communities in the Vestfold Hills, East Antarctica – ERRATUM
- Laurence J. Clarke, Eric J. Raes, Toby Travers, Patti Virtue, Dana M. Bergstrom
-
- Journal:
- Antarctic Science , First View
- Published online by Cambridge University Press:
- 23 April 2024, p. 1
-
- Article
-
- You have access Access
- HTML
- Export citation
VaTEST III: Validation of eight potential super-earths from TESS data
- Priyashkumar Mistry, Aniket Prasad, Mousam Maity, Kamlesh Pathak, Sarvesh Gharat, Georgios Lekkas, Surendra Bhattarai, Dhruv Kumar, Jack J. Lissauer, Joseph D. Twicken, Abderahmane Soubkiou, Francisco J. Pozuelos, Jon Jenkins, Keith Horne, Steven Giacalone, Khalid Barkaoui, Mathilde Timmermans, Cristilyn N. Watkins, Ramotholo Sefako, Karen A. Collins, David R. Ciardi, Catherine A. Clark, Boris S. Safonov, Avi Shporer, Joshua E. Schlieder, Zouhair Benkhaldoun, Chris Stockdale, Carl Ziegler, Emily A. Gilbert, Jehin Emmanuël, Felipe Murgas, Ian J. M. Crossfield, Martin Paegert, Michael B. Lund, Norio Narita, Richard P. Schwarz, Robert F. Goeke, Sergio B. Fajardo-Acosta, Steve B. Howell, Thiam-Guan Tan, Thomas Barclay, Yugo Kawai
-
- Journal:
- Publications of the Astronomical Society of Australia / Volume 41 / 2024
- Published online by Cambridge University Press:
- 11 April 2024, e030
-
- Article
- Export citation
-
NASA’s all-sky survey mission, the Transiting Exoplanet Survey Satellite (TESS), is specifically engineered to detect exoplanets that transit bright stars. Thus far, TESS has successfully identified approximately 400 transiting exoplanets, in addition to roughly 6 000 candidate exoplanets pending confirmation. In this study, we present the results of our ongoing project, the Validation of Transiting Exoplanets using Statistical Tools (VaTEST). Our dedicated effort is focused on the confirmation and characterisation of new exoplanets through the application of statistical validation tools. Through a combination of ground-based telescope data, high-resolution imaging, and the utilisation of the statistical validation tool known as TRICERATOPS, we have successfully discovered eight potential super-Earths. These planets bear the designations: TOI-238b (1.61$^{+0.09} _{-0.10}$ R$_\oplus$), TOI-771b (1.42$^{+0.11} _{-0.09}$ R$_\oplus$), TOI-871b (1.66$^{+0.11} _{-0.11}$ R$_\oplus$), TOI-1467b (1.83$^{+0.16} _{-0.15}$ R$_\oplus$), TOI-1739b (1.69$^{+0.10} _{-0.08}$ R$_\oplus$), TOI-2068b (1.82$^{+0.16} _{-0.15}$ R$_\oplus$), TOI-4559b (1.42$^{+0.13} _{-0.11}$ R$_\oplus$), and TOI-5799b (1.62$^{+0.19} _{-0.13}$ R$_\oplus$). Among all these planets, six of them fall within the region known as ‘keystone planets’, which makes them particularly interesting for study. Based on the location of TOI-771b and TOI-4559b below the radius valley we characterised them as likely super-Earths, though radial velocity mass measurements for these planets will provide more details about their characterisation. It is noteworthy that planets within the size range investigated herein are absent from our own solar system, making their study crucial for gaining insights into the evolutionary stages between Earth and Neptune.
Chemisorption of Cu(II) and Co(II) on Allophane and Imogolite
- C. J. Clark, M. B. McBride
-
- Journal:
- Clays and Clay Minerals / Volume 32 / Issue 4 / August 1984
- Published online by Cambridge University Press:
- 02 April 2024, pp. 300-310
-
- Article
- Export citation
-
Adsorption of Cu2+ and Co2+ by synthetic imogolite, synthetic allophanes with a range of SiO2/ Al2O3 ratios, and allophanic clay fractions from volcanic ash soils was measured in an ionic medium of 0.05 M Ca(NO3)2. The effect of pH (and metal concentration) on adsorption was qualitatively similar for the synthetic and natural allophanes with relatively minor changes in behavior caused by variable SiO2/Al2O3 ratios. Cu and Co were chemisorbed by allophane at pH 5.0–5.5 and 6.9–7.2 (pH values for 50% adsorption level), respectively, with concomitant release of 1.6–1.9 protons/metal ion adsorbed. Quantitatively, adsorption by imogolite was less than that by the allophanes, presumably because of fewer sites available for chemisorption on the tubular structure of imogolite. Electron spin resonance studies of the imogolite and allophanes revealed that Cu2+ was adsorbed as a monomer on two types of surface sites. The preferred sites were likely adjacent AlOH groups binding Cu2+ by a binuclear mechanism; weaker bonding occurred at isolated AlOH or SiOH groups. These chemisorbed forms of Cu2+ were readily extracted by EDTA, CH3COOH, and metals capable of specific adsorption, but were not exchangeable. In addition, the H2O and/or OH− ligands of chemisorbed Cu2+ were readily displaced by NH3, with the formation of ternary Cu-ammonia-surface complexes.
Resilication of Bauxite at the Alabama Street Mine, Saline County, Arkansas, Illustrated by Scanning Electron Micrographs
- W. D. Keller, Otis M. Clarke, Jr.
-
- Journal:
- Clays and Clay Minerals / Volume 32 / Issue 2 / April 1984
- Published online by Cambridge University Press:
- 02 April 2024, pp. 139-146
-
- Article
- Export citation
-
Resilication of bauxite produced kaolin at and beneath an old erosion surface on bauxite at the Alabama Street Mine of ALCOA in Saline County, Arkansas. The transitional alteration can be traced in morphology by scanning electron microscopy, (SEM) and in Al:Si ratio by energy dispersive analysis. In one illustrated example, the sequence of resilication took place within 1 mm thickness; in another, across 80 mm. The first morphologic alteration of gibbsite (bauxite) appears to be to allophane that occurs in micrometer-size plates which show elongate cracking and/or straight to highly curved elongate edges. The next phase is kaolinite, first in micrometer-size flakes followed by coarser flakes that grade into a zone of typical stacked kaolinite, likewise identified by X-ray powder diffraction. Notably large stacks and small flakes of kaolinite are intimately mixed in the SEMs, thus suggesting that unequal sizes of kaolinite crystals can grow during one episode of an in-situ genesis.
Crystallization of Iron Oxides on Calcite Surfaces in Static Systems
- E. T. Clarke, R. H. Loeppert, J. M. Ehrman
-
- Journal:
- Clays and Clay Minerals / Volume 33 / Issue 2 / April 1985
- Published online by Cambridge University Press:
- 02 April 2024, pp. 152-158
-
- Article
- Export citation
-
Iron salts react readily with calcite in oxidizing calcareous environments to produce solid phase Fe-oxides. These reactions represent important processes in aqueous, geologic, and pedogenic environments. In the present investigation, Fe-oxides were precipitated from Fe(ClO4)2 solutions on undisturbed calcite grains in aqueous suspension. In this way it was possible to investigate the sequence of events in the crystallization process. Following an initial precipitation on the calcite grains, a period of slow growth of lepidocrocite was noted wherein 4-μm euhedral platelets formed with uniform orientation perpendicular to the calcite surface. The slow growth and highly crystalline nature of the Fe-oxide product may be partially due to the diffusion barrier formed by the growing oxide crystal mass which influenced rate of movement of HCO3− to the dissolved Fe phase and Fe ions and H+ towards the calcite surface. Upon continued aging, the supernate became noticeably opaque. As the suspended nuclei settled, new surfaces for crystal growth were provided which resulted in somewhat less crystalline lepidocrocite and goethite.
Cation and Anion Retention by Natural and Synthetic Allophane and Imogolite
- C. J. Clark, M. B. McBride
-
- Journal:
- Clays and Clay Minerals / Volume 32 / Issue 4 / August 1984
- Published online by Cambridge University Press:
- 02 April 2024, pp. 291-299
-
- Article
- Export citation
-
The negative surface charge of synthetic allophanes with a range of Si/Al ratios decreased and positive charge increased with increasing alumina content at a given pH. The phosphate adsorption capacity also increased with increasing Al content. That this relationship between composition and chemical reactivity was not found for the soil allophanes is attributed to the presence of specifically adsorbed organic or inorganic anions on the natural material. Both synthetic and natural imogolites had a much lower capacity to adsorb phosphate than the allophanes and adsorbed anomalously high amounts of Cl− and ClO4− at high pH. It is proposed that intercalation of salt occurs in imogolite, although electron spin resonance studies using spin probes failed to reveal the trapping of small organic molecules in imogolite tubes. These spin probes in the carboxylated form did, however, suggest an electrostatic retention of carboxylate by imogolite and a more specific adsorption by allophane involving ligand exchange of surface hydroxyl. The results illustrate the inherent differences in charge and surface properties of allophane and imogolite despite the common structural unit which the two minerals incorporate.
Extremophile hypolithic communities in the Vestfold Hills, East Antarctica
- Laurence J. Clarke, Eric J. Raes, Toby Travers, Patti Virtue, Dana M. Bergstrom
-
- Journal:
- Antarctic Science , First View
- Published online by Cambridge University Press:
- 25 March 2024, pp. 1-17
-
- Article
-
- You have access Access
- HTML
- Export citation
-
The Vestfold Hills are a 400 km2, isolated ice-free oasis in eastern Antarctica featuring large areas with translucent quartz rocks that provide habitat for hypolithic microbial communities underneath. We used high-throughput DNA sequencing of 16S and 18S ribosomal RNA amplicons to characterize bacterial and eukaryotic hypolithic communities across the Vestfold Hills. We found high-level, local heterogeneity in community structure consistent with limited dispersal between hypoliths. Hypolithic communities were dominated by heterotrophic Bacteroidetes (mean bacterial relative read abundance: 56%) as well as Cyanobacteria (35%), with the eukaryote component often dominated by Chlorophyta (43%). Small but significant proportions of the variation in microbial community composition and function were explained by soil salinity (5–7%) and water availability (8–11%), with distinct taxa associated with different salinities and water availabilities. Furthermore, many inferred bacterial metabolic pathways were enriched in hypolithic communities from either dry or high-salinity sites. Vestfold Hills hypolithic habitats are likely to be local refuges for bacterial and eukaryotic diversity. Gradients in soil salinity and water availability across the Vestfold Hills, in addition to the number and diversity of lake types and fjords as potential source populations, may contribute to the observed variation in the extremophile, hypolithic microbial community composition.
Head and Neck Cancer: United Kingdom National Multidisciplinary Guidelines, Sixth Edition
- Jarrod J Homer, Stuart C Winter, Elizabeth C Abbey, Hiba Aga, Reshma Agrawal, Derfel ap Dafydd, Takhar Arunjit, Patrick Axon, Eleanor Aynsley, Izhar N Bagwan, Arun Batra, Donna Begg, Jonathan M Bernstein, Guy Betts, Colin Bicknell, Brian Bisase, Grainne C Brady, Peter Brennan, Aina Brunet, Val Bryant, Linda Cantwell, Ashish Chandra, Preetha Chengot, Melvin L K Chua, Peter Clarke, Gemma Clunie, Margaret Coffey, Clare Conlon, David I Conway, Florence Cook, Matthew R Cooper, Declan Costello, Ben Cosway, Neil J A Cozens, Grant Creaney, Gahir K Daljit, Stephen Damato, Joe Davies, Katharine S Davies, Alina D Dragan, Yong Du, Mark R D Edmond, Stefano Fedele, Harriet Finze, Jason C Fleming, Bernadette H Foran, Beth Fordham, Mohammed M A S Foridi, Lesley Freeman, Katherine E Frew, Pallavi Gaitonde, Victoria Gallyer, Fraser W Gibb, Sinclair M Gore, Mark Gormley, Roganie Govender, J Greedy, Teresa Guerrero Urbano, Dorothy Gujral, David W Hamilton, John C Hardman, Kevin Harrington, Samantha Holmes, Jarrod J Homer, Deborah Howland, Gerald Humphris, Keith D Hunter, Kate Ingarfield, Richard Irving, Kristina Isand, Yatin Jain, Sachin Jauhar, Sarra Jawad, Glyndwr W Jenkins, Anastasios Kanatas, Stephen Keohane, Cyrus J Kerawala, William Keys, Emma V King, Anthony Kong, Fiona Lalloo, Kirsten Laws, Samuel C Leong, Shane Lester, Miles Levy, Ken Lingley, Gitta Madani, Navin Mani, Paolo L Matteucci, Catriona R Mayland, James McCaul, Lorna K McCaul, Pádraig McDonnell, Andrew McPartlin, Valeria Mercadante, Zoe Merchant, Radu Mihai, Mufaddal T Moonim, John Moore, Paul Nankivell, Sonali Natu, A Nelson, Pablo Nenclares, Kate Newbold, Carrie Newland, Ailsa J Nicol, Iain J Nixon, Rupert Obholzer, James T O'Hara, S Orr, Vinidh Paleri, James Palmer, Rachel S Parry, Claire Paterson, Gillian Patterson, Joanne M Patterson, Miranda Payne, L Pearson, David N Poller, Jonathan Pollock, Stephen Ross Porter, Matthew Potter, Robin J D Prestwich, Ruth Price, Mani Ragbir, Meena S Ranka, Max Robinson, Justin W G Roe, Tom Roques, Aleix Rovira, Sajid Sainuddin, I J Salmon, Ann Sandison, Andy Scarsbrook, Andrew G Schache, A Scott, Diane Sellstrom, Cherith J Semple, Jagrit Shah, Praveen Sharma, Richard J Shaw, Somiah Siddiq, Priyamal Silva, Ricard Simo, Rabin P Singh, Maria Smith, Rebekah Smith, Toby Oliver Smith, Sanjai Sood, Francis W Stafford, Neil Steven, Kay Stewart, Lisa Stoner, Steve Sweeney, Andrew Sykes, Carly L Taylor, Selvam Thavaraj, David J Thomson, Jane Thornton, Neil S Tolley, Nancy Turnbull, Sriram Vaidyanathan, Leandros Vassiliou, John Waas, Kelly Wade-McBane, Donna Wakefield, Amy Ward, Laura Warner, Laura-Jayne Watson, H Watts, Christina Wilson, Stuart C Winter, Winson Wong, Chui-Yan Yip, Kent Yip
-
- Journal:
- The Journal of Laryngology & Otology / Volume 138 / Issue S1 / April 2024
- Published online by Cambridge University Press:
- 14 March 2024, pp. S1-S224
- Print publication:
- April 2024
-
- Article
-
- You have access Access
- Open access
- HTML
- Export citation
A review of records and research actions for the poorly known Vanuatu Petrel Pterodroma [cervicalis] occulta
- Peter M. Vaughan, Jeremy P. Bird, Vincent Bretagnolle, Hadoram Shirihai, Alan J. D. Tennyson, Colin M. Miskelly, Rohan H. Clarke
-
- Journal:
- Bird Conservation International / Volume 34 / 2024
- Published online by Cambridge University Press:
- 14 February 2024, e9
-
- Article
-
- You have access Access
- Open access
- HTML
- Export citation
-
Gadfly petrels Pterodroma spp. are among the most threatened bird taxa. Conservation interventions have been successfully developed and applied for some gadfly petrel species, but a substantial gap remains in conservation science for this group in the tropical Pacific Ocean. The Vanuatu Petrel Pterodroma [cervicalis] occulta is an ideal exemplar to develop a pipeline for conservation science in tropical Pacific gadfly petrels as it is subject to many of the challenges facing other gadfly petrel taxa in the region. We review over 40 pelagic Vanuatu Petrel records and five research expeditions to the only known colony on the island of Vanua Lava, Vanuatu. These records provide a baseline from which to recommend conservation research actions for the taxon. The population status, taxonomy, distribution, and threat profile of the taxon are all poorly known, and these areas are high priorities for future research.
The predictive role of symptoms in COVID-19 diagnostic models: A longitudinal insight
- Olivia Bird, Eva P. Galiza, David Neil Baxter, Marta Boffito, Duncan Browne, Fiona Burns, David R. Chadwick, Rebecca Clark, Catherine A. Cosgrove, James Galloway, Anna L. Goodman, Amardeep Heer, Andrew Higham, Shalini Iyengar, Christopher Jeanes, Philip A. Kalra, Christina Kyriakidou, Judy M. Bradley, Chigomezgo Munthali, Angela M. Minassian, Fiona McGill, Patrick Moore, Imrozia Munsoor, Helen Nicholls, Orod Osanlou, Jonathan Packham, Carol H. Pretswell, Alberto San Francisco Ramos, Dinesh Saralaya, Ray P. Sheridan, Richard Smith, Roy L. Soiza, Pauline A. Swift, Emma C. Thomson, Jeremy Turner, Marianne Elizabeth Viljoen, Paul T. Heath, Irina Chis Ster
-
- Journal:
- Epidemiology & Infection / Volume 152 / 2024
- Published online by Cambridge University Press:
- 22 January 2024, e37
-
- Article
-
- You have access Access
- Open access
- HTML
- Export citation
-
To investigate the symptoms of SARS-CoV-2 infection, their dynamics and their discriminatory power for the disease using longitudinally, prospectively collected information reported at the time of their occurrence. We have analysed data from a large phase 3 clinical UK COVID-19 vaccine trial. The alpha variant was the predominant strain. Participants were assessed for SARS-CoV-2 infection via nasal/throat PCR at recruitment, vaccination appointments, and when symptomatic. Statistical techniques were implemented to infer estimates representative of the UK population, accounting for multiple symptomatic episodes associated with one individual. An optimal diagnostic model for SARS-CoV-2 infection was derived. The 4-month prevalence of SARS-CoV-2 was 2.1%; increasing to 19.4% (16.0%–22.7%) in participants reporting loss of appetite and 31.9% (27.1%–36.8%) in those with anosmia/ageusia. The model identified anosmia and/or ageusia, fever, congestion, and cough to be significantly associated with SARS-CoV-2 infection. Symptoms’ dynamics were vastly different in the two groups; after a slow start peaking later and lasting longer in PCR+ participants, whilst exhibiting a consistent decline in PCR- participants, with, on average, fewer than 3 days of symptoms reported. Anosmia/ageusia peaked late in confirmed SARS-CoV-2 infection (day 12), indicating a low discrimination power for early disease diagnosis.
Sedimenting-particle redistribution in a horizontal Couette
- M. Davoodi, A. Clarke
-
- Journal:
- Journal of Fluid Mechanics / Volume 979 / 25 January 2024
- Published online by Cambridge University Press:
- 17 January 2024, A37
-
- Article
- Export citation
-
Flow between axially rotating concentric cylinders is well known to exhibit rich dynamics. Hence, Taylor instabilities have been studied, both experimentally and theoretically, for many years. Although usually studied in the abstract, such geometries arise in a range of practical situations including drilling, when a drilling fluid flow enters a well via a pipe that is the centre body and returns via the annulus between the pipe and the borehole wall. In drilling, the centre body rotates and the annular flow contains rock cuttings. Here, we report the development of an Eulerian-Eulerian solver, based on OpenFOAM, that solves for this cuttings transport problem in the presence of both gravity and Taylor vortices. To check the reliability of the solver, we conduct a set of experiments spanning a wide range of complex flow regimes. We show that the model successfully predicts, in all regimes, the observed complex redistribution of particulates. However, for suspension flows under viscously dominated conditions, high particle concentrations and in rectilinear flow, particle pressure and normal stress differences are sufficient to capture particle migration. Results show that in more complex flows exemplified by the Taylor–Couette flow studied here, more realistic predictions of non-Brownian particle migration require inclusion of forces arising through the relative velocity of the two phases including lift forces originating both from inertia and particle rotation.
6 Remote Smartphone Cognitive and Motor Testing in Frontotemporal Dementia Research: Feasibility, Reliability, and Validity
- Adam M Staffaroni, Jack Carson Taylor, Annie L Clark, Hilary W Heuer, Amy B Wise, Masood Manoochehri, Leah Forsberg, Carly T Mester, Meghana Roa, Danielle Brushaber, Julio C Rojas, Joel H Kramer, Bradley F Boeve, Howard J Rosen, Adam L Boxer
-
- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 604-605
-
- Article
-
- You have access Access
- Export citation
-
Objective:
Therapeutics targeting frontotemporal dementia (FTD) are entering clinical trials. There are challenges to conducting these studies, including the relative rarity of the disease. Remote assessment tools could increase access to clinical research and pave the way for decentralized clinical trials. We developed the ALLFTD Mobile App, a smartphone application that includes assessments of cognition, speech/language, and motor functioning. The objectives were to determine the feasibility and acceptability of collecting remote smartphone data in a multicenter FTD research study and evaluate the reliability and validity of the smartphone cognitive and motor measures.
Participants and Methods:A diagnostically mixed sample of 207 participants with FTD or from familial FTD kindreds (CDR®+NACC-FTLD=0 [n=91]; CDR®+NACC-FTLD=0.5 [n=39]; CDR®+NACC-FTLD>1 [n=39]; unknown [n=38]) were asked to remotely complete a battery of tests on their smartphones three times over two weeks. Measures included five executive functioning (EF) tests, an adaptive memory test, and participant experience surveys. A subset completed smartphone tests of balance at home (n=31) and a finger tapping test (FTT) in the clinic (n=11). We analyzed adherence (percentage of available measures that were completed) and user experience. We evaluated Spearman-Brown split-half reliability (100 iterations) using the first available assessment for each participant. We assessed test-retest reliability across all available assessments by estimating intraclass correlation coefficients (ICC). To investigate construct validity, we fit regression models testing the association of the smartphone measures with gold-standard neuropsychological outcomes (UDS3-EF composite [Staffaroni et al., 2021], CVLT3-Brief Form [CVLT3-BF] Immediate Recall, mechanical FTT), measures of disease severity (CDR®+NACC-FTLD Box Score & Progressive Supranuclear Palsy Rating Scale [PSPRS]), and regional gray matter volumes (cognitive tests only).
Results:Participants completed 70% of tasks. Most reported that the instructions were understandable (93%), considered the time commitment acceptable (97%), and were willing to complete additional assessments (98%). Split-half reliability was excellent for the executive functioning (r’s=0.93-0.99) and good for the memory test (r=0.78). Test-retest reliabilities ranged from acceptable to excellent for cognitive tasks (ICC: 0.70-0.96) and were excellent for the balance (ICC=0.97) and good for FTT (ICC=0.89). Smartphone EF measures were strongly associated with the UDS3-EF composite (ß's=0.6-0.8, all p<.001), and the memory test was strongly correlated with total immediate recall on the CVLT3-BF (ß=0.7, p<.001). Smartphone FTT was associated with mechanical FTT (ß=0.9, p=.02), and greater acceleration on the balance test was associated with more motor features (ß=0.6, p=0.02). Worse performance on all cognitive tests was associated with greater disease severity (ß's=0.5-0.7, all p<.001). Poorer performance on the smartphone EF tasks was associated with smaller frontoparietal/subcortical volume (ß's=0.4-0.6, all p<.015) and worse memory scores with smaller hippocampal volume (ß=0.5, p<.001).
Conclusions:These results suggest remote digital data collection of cognitive and motor functioning in FTD research is feasible and acceptable. These findings also support the reliability and validity of unsupervised ALLFTD Mobile App cognitive tests and provide preliminary support for the motor measures, although further study in larger samples is required.
1 Social Support is Associated with Better Memory Performance among Hispanic/Latino, but not Non-Hispanic White Older Adults
- Abbey M Hamlin, Jordana Breton, Nazareth Ortega, Joaquin Urquiza-Perez, Lauren Eisenstat, Megan Perry, Thaha Hossain, Sanya Kotian, Alexandra L Clark
-
- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 317-318
-
- Article
-
- You have access Access
- Export citation
-
Objective:
Hispanic/Latino (H/L) older adults are at greater risk of developing Alzheimer’s disease and related dementias compared to non-Hispanic whites (NHW), and there is an urgent need to identify important factors that may help prevent and/or reduce age-related cognitive health disparities. Positive psychosocial factors, such as social support, may protect against cognitive impairment and decline. However, recent research has highlighted that the effect of social support on cognitive outcomes may differ across racial/ethnic groups. Given the emphasis placed on family relationships and support in H/L culture, the current study sought to clarify whether H/L ethnicity moderated the association between social support and cognitive functioning in a well-characterized sample of community-dwelling older adults residing in Texas.
Participants and Methods:Participants included 766 NHW and 817 H/L (predominantly Mexican American) older adults (Mage = 66.25 ±8.64) without dementia enrolled in the Health and Aging Brain Study-Health Disparities. Participants completed study questionnaires and a comprehensive neuropsychological battery. Perceived social support was measured using the total sum score from the 12-item abbreviated version of the Interpersonal Support Evaluation List. Episodic memory performance was operationalized as the z-score composite of the immediate and delayed recall totals from the Spanish English Verbal Learning Test and the Weschler Memory Scale (WMS)-III Logical Memory 1 and 2. Executive functioning was operationalized as the z-score composite of scores from the WMS-III Digit Span, Verbal Fluency (FAS), and Trails B. Analyses of covariance were used to explore racial/ethnic group differences in self-reported levels of social support. Multiple linear regression models examined (1) ethnicity x social support interactions on cognition, and (2) ethnicity-stratified social support and cognition associations. Covariates included age, education, sex, yearly income, and depressive symptoms.
Results:H/L older adults reported less perceived social support compared to NHWs (F = 41.16, p < .001). There were no significant ethnicity x social support interactions on episodic memory (ß = 0.04, p = .53) or executive functioning (ß = 0.004, p = .95). However, stratified models revealed that more social support was associated with better memory performance in H/Ls (ß = 0.08, p = .01), but not in NHWs (ß = 0.0004, p = .99). No significant associations between social support and executive functioning were observed amongst H/Ls (ß = -0.01, p = .60) or NHWs (ß = 0.04, p = .29).
Conclusions:Although H/Ls reported lower levels of social support relative to NHWs, we observed that social support was linked to better memory performance within the H/L group only. Results suggest that culturally tailored interventions which encourage strong interpersonal relationships and caring for family could enhance social support in H/Ls and thus help to prevent memory decline. Future work should focus on the development of assessment measures that better characterize unique cultural elements of social support within H/Ls, such as multigenerational households, and explore the direct effects of social support on brain metrics.
5 Poorer Memory Outcomes are Observed in Underinsured Latino Older Adults with Metabolic Syndrome
- Jordana Breton, Abbey M Hamlin, Nazareth Ortega, Joaquin Urquiza-Perez, Thaha Hossain, Megan Perry, Lauren Eisenstat, Sanya Kotian, Alexandra L Clark
-
- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 787-788
-
- Article
-
- You have access Access
- Export citation
-
Objective:
Metabolic Syndrome (MetS) is a constellation of deleterious cardiometabolic health conditions (e.g., diabetes, hypertension) that have been linked to cognitive impairment and accelerated cognitive decline in older adults. Research has shown that Latinos are at increased risk for developing MetS relative to non-Latino Whites and the prevention, maintenance, and treatment of cardiometabolic risk factors are largely contingent upon health insurance status. Within the United States there are considerable state-based differences in eligibility and access to health insurance coverage. Although Texas has the second largest population of Latinos, they are one of the most underinsured groups within the state. There is some evidence to suggest that inconsistent healthcare is associated with cognitive impairment among underserved/underprivileged groups. The current study sought to examine whether insurance status moderates the association between MetS and cognitive functioning in an effort to inform public health policy initiatives vital to reducing age-related health disparities amongst Latino older adults residing in Texas.
Participants and Methods:The study sample included 850 primarily Spanish-speaking (67.6%) Latino older adults (mean age = 63.1±7.81) largely of Mexican origin/descent (95%) enrolled in the Health and Aging Brain Study-Health Disparities. All participants completed neuropsychological testing, a health exam, and questions about health insurance coverage. MetS status (MetS+ vs. MetS-) was determined by abnormal clinical abdominal obesity, triglycerides, high-density lipoprotein, blood pressure, and fasting glucose values. Health insurance status was determined by current enrollment in any private or public insurance plan. Cognition was assessed with Digit Span, Logical Memory I and II, Trail Making Test (A and B), Spanish-English Verbal Learning Test, and Letter Fluency (FAS). Raw scores were converted to z-scores which were subsequently averaged into two distinct memory and executive functioning composite scores. ANCOVAs controlling for age, sex, education, APOE e4 positivity, annual income, and primary language status were used examine health insurance status x MetS interactions on cognitive composites.
Results:Approximately 54.6% of the sample met clinical criteria for MetS+ and 23.6% endorsed having no health insurance. There were no significant group differences in the proportion of MetS+ and MetS- individuals with and without health insurance (X 2 = .002, p =.96). Results revealed there was a significant MetS x health insurance status interaction on the memory composite (F = 5.39, p = .02). Post-hoc comparisons revealed that Latino older adults without health insurance demonstrated poorer memory performance relative to those with health insurance in the MetS+ group (p=.02). In contrast, there were no significant differences in memory performance across insurance status in the MetS- group (p=.35). Finally, there was no significant MetS x health insurance interaction on executive functioning (p=.60).
Conclusions:Findings revealed that health insurance coverage differentially impacts memory, but not executive functioning, amongst Latinos with MetS+. Underinsured Latinos with chronic cardiometabolic health conditions may be at risk for poor memory outcomes and increasing access to affordable healthcare could help mitigate the adverse effects of MetS+ on memory. Future studies examining the relationship between health insurance, MetS status, and neuroimaging markers may yield additional insight into mechanisms underlying age-related dementia disparities.
18 Vascular Risk, Cerebral White Matter, and Executive Functioning in Vietnam-Era Veterans with Traumatic Brain Injury and/or Post-Traumatic Stress Disorder: A Department of Defense Alzheimer’s Disease Initiative (DoD-ADNI) Study
- Makenna B McGill, Alexandra L Clark, David M Schnyer
-
- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 127-128
-
- Article
-
- You have access Access
- Export citation
-
Objective:
Research indicates that Veterans with a history of traumatic brain injury (TBI) are at increased risk for dementia. Although the precise mechanisms underlying this relationship are poorly understood, remote TBI may exacerbate normal age-related changes to cerebral white matter (WM) and result in cognitive decline. However, Veterans commonly experience a constellation of mental (e.g., post-traumatic stress disorder [PTSD] and depression) and vascular (e.g., diabetes, hypertension, obesity) health conditions that have also been implicated in pathologic cerebral WM and cognitive aging trajectories. Therefore, the present study sought to (1) clarify the effects of remote TBI within the context of PTSD, depression, and vascular risk on WM micro- and macrostructure, and (2) explore if WM integrity is associated with cognition in a sample of Vietnam-Era Veterans.
Participants and Methods:The sample consisted of 195 male Veterans ages 60-80 (mean age=69.3) enrolled in the Department of Defense-Alzheimer’s Disease Neuroimaging Initiative (DoD-ADNI) study. 102 Veterans met criteria for TBI by sustaining a head-injury that resulted in a loss of consciousness, alteration of consciousness, or post-traumatic amnesia. Current and/or lifetime PTSD was designated by scores >30 on the Clinician-Administered PTSD Scale. The Geriatric Depression Scale was used as a continuous measure of depression. A vascular risk score (0-3) was calculated based on diabetes, hypertension, and obesity (BMI >30 kg/m2). An executive functioning composite was created by averaging sample-specific z-scores for Trail Making Tests (A and B), with higher scores indicating worse performance. Voxelwise analysis of WM microstructure (fractional anisotropy [FA]) was conducted with Tract-Based Spatial Statistics (TBSS), using non-parametric permutation testing with threshold-free cluster enhancement. SPM’s Lesion Segmentation Tool was used to investigate WM macrostructure (WM hyperintensity [WMH] volume). Lesion probability maps were masked to restrict WMH volume calculations to WM. Robust regression using M-estimation and predictive R2 calculated using 10-fold cross-validation examined WMH volume, predictor, and cognitive associations. Age was a covariate in all WM analyses, and education was a covariate in all cognitive analyses.
Results:TBSS analysis revealed widespread, significant negative relationships between vascular risk and FA across numerous WM tracts (p’s<0.05). These associations remained significant after adjusting for TBI history, PTSD, and depression. TBSS identified significant positive relationships between executive functioning performance and FA across similar brain regions (p’s<0.05). Robust regressions revealed that vascular risk significantly predicted WMH volume (p=0.006; ß=0.161; R2=0.093), whereas TBI history, PTSD, and depression did not (p’s=0.107-0.166; ß's=-0.089-0.101). WMH volume significantly predicted executive functioning (p=0.002; ß=0.216; R2=0.105), whereas TBI history, PTSD, depression, and vascular risk did not (p’s=0.123-0.888; ß's=-0.012-0.125).
Conclusions:Our results suggest that vascular health, relative to remote TBI, PTSD, and depression, may be more robustly associated with cerebral WM micro- and macrostructure in older Veterans. Furthermore, poorer WM integrity is associated with poorer cognitive performance. These findings underscore the importance of vascular health interventions in preventing negative brain and cognitive aging outcomes in Veterans, independent of TBI history. Future studies might leverage other neuroimaging modalities (e.g., functional MRI) to further investigate the effects of vascular health on aging in Veterans with a history of TBI.
2 Neuropsychological Predictors of Posttraumatic Stress Disorder and Depressive Symptom Improvement in Compensatory Cognitive Training for Veterans with a History of Mild Traumatic Brain Injury
- Amber V Keller, Jillian M.R. Clark, Jacqueline E Maye, Amy J Jak, Maya E O’Neil, Rhonda M Williams, Aaron P Turner, Kathleen F Pagulayan, Elizabeth W Twamley
-
- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 515-517
-
- Article
-
- You have access Access
- Export citation
-
Objective:
Mild traumatic brain injury (mTBI), depression, and posttraumatic stress disorder (PTSD) are a notable triad in Operation Enduring Freedom, Operation Iraqi Freedom, and Operation New Dawn (OEF/OIF/OND) Veterans. With the comorbidity of depression and PTSD in Veterans with mTBI histories, and their role in exacerbating cognitive and emotional dysfunction, interventions addressing cognitive and psychiatric functioning are critical. Compensatory Cognitive Training (CCT) is associated with improvements in areas such as prospective memory, attention, and executive functioning and has also yielded small-to-medium treatment effects on PTSD and depressive symptom severity. Identifying predictors of psychiatric symptom change following CCT would further inform the interventional approach. We sought to examine neuropsychological predictors of PTSD and depressive symptom improvement in Veterans with a history of mTBI who received CCT.
Participants and Methods:37 OEF/OIF/OND Veterans with mTBI history and cognitive complaints received 10-weekly 120-minute CCT group sessions as part of a clinical trial. Participants completed a baseline neuropsychological assessment including tests of premorbid functioning, attention/working memory, processing speed, verbal learning/memory, and executive functioning, and completed psychiatric symptom measures (PTSD Checklist-Military Version; Beck Depression Inventory-II) at baseline, post-treatment, and 5-week follow-up. Paired samples t-tests were used to examine statistically significant change in PTSD (total and symptom cluster scores) and depressive symptom scores over time. Pearson correlations were calculated between neuropsychological scores and PTSD and depressive symptom change scores at post-treatment and follow-up. Neuropsychological measures identified as significantly correlated with psychiatric symptom change scores (p^.05) were entered as independent variables in separate multiple linear regression analyses to predict symptom change at post-treatment and follow-up.
Results:Over 50% of CCT participants had clinically meaningful improvement in depressive symptoms (>17.5% score reduction) and over 20% had clinically meaningful improvement in PTSD symptoms (>10-point improvement) at post-treatment and follow-up. Examination of PTSD symptom cluster scores (re-experiencing, avoidance/numbing, and arousal) revealed a statistically significant improvement in avoidance/numbing at follow-up. Bivariate correlations indicated that worse baseline performance on D-KEFS Category Fluency was moderately associated with PTSD symptom improvement at post-treatment. Worse performance on both D-KEFS Category Fluency and Category Switching Accuracy was associated with improvement in depressive symptoms at post-treatment and follow-up. Worse performance on D-KEFS Trail Making Test Switching was associated with improvement in depressive symptoms at follow-up. Subsequent regression analyses revealed worse processing speed and worse aspects of executive functioning at baseline significantly predicted depressive symptom improvement at post-treatment and follow-up.
Conclusions:Worse baseline performances on tests of processing speed and aspects of executive functioning were significantly associated with improvements in PTSD and depressive symptoms during the trial. Our results suggest that cognitive training may bolster skills that are helpful for PTSD and depressive symptom reduction and that those with worse baseline functioning may benefit more from treatment because they have more room to improve. Although CCT is not a primary treatment for PTSD or depressive symptoms, our results support consideration of including CCT in hybrid treatment approaches. Further research should examine these relationships in larger samples.
1 Associations of Locus of Control and Memory Self-Awareness in Older Adults with and without MCI
- Mary E Garcia, Jeanine M Parisi, Sarah Cook, Ian McDonough, Alexandra J Weigand, Alexandra L Clark, Michael Marsiske, Kelsey R Thomas
-
- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 676-677
-
- Article
-
- You have access Access
- Export citation
-
Objective:
While loss of insight into one’s cognitive impairment (anosognosia) is a feature in Alzheimer’s disease dementia, less is known about memory self-awareness in cognitively unimpaired (CU) older adults or mild cognitive impairment (MCI) or factors that may impact self-awareness. Locus of control, specifically external locus of control, has been linked to worse cognitive/health outcomes, though little work has examined locus of control as it relates to self-awareness of memory functioning or across cognitive impairment status. Therefore, we examined associations between locus of control and memory self-awareness and whether MCI status impacted these associations.
Participants and Methods:Participants from the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study (mean age=73.51; 76% women; 26% Black/African American) were classified as CU (n=2177) or MCI (amnestic n=313; non-amnestic n=170) using Neuropsychological Criteria. A memory composite score measured objective memory performance and the Memory Functioning Questionnaire measured subjective memory. Memory self-awareness was defined as objective memory minus subjective memory, with positive values indicating overreporting of memory difficulties relative to actual performance (hypernosognosia) and negative values indicating underreporting (hyponosognosia). Internal (i.e., personal skills/attributes dictate life events) and external (i.e., environment/others dictate life events) locus of control scores came from the Personality in Intellectual Aging Contexts Inventory. General linear models, adjusting for age, education, sex/gender, depressive symptoms, general health, and vocabulary examined the effects of internal and external locus of control on memory self-awareness and whether MCI status moderated these associations.
Results:Amnestic and non-amnestic MCI participants reported lower internal and higher external locus of control than CU participants. There was a main effect of MCI status on memory self-awareness such that amnestic MCI participants showed the greatest degree of hyponosognosia/underreporting, followed by non-amnestic MCI, and CU participants slightly overreported their memory difficulties. While, on average, participants were fairly accurate at reporting their degree of memory difficulty, internal locus of control was negatively associated with self-awareness such that higher internal locus of control was associated with greater underreporting (ß=-.127, 95% CI [-.164, -.089], p<.001). MCI status did not moderate this association. External locus of control was positively associated with self-awareness such that higher external locus of control was associated with greater hypernosonosia/overreporting (ß=.259, 95% CI [.218, .300], p<.001). Relative to CU, amnestic, but not non-amnestic, MCI showed a stronger association between external locus of control and memory self-awareness. Specifically, higher external locus of control was associated with less underreporting of cognitive difficulties in amnestic MCI (ß=.107, 95% CI [.006, .208], p=.038).
Conclusions:In CU participants, higher external locus of control was associated with greater hypernosognosia/overreporting. In amnestic MCI, the lower external locus of control associations with greater underreporting of objective cognitive difficulties suggests that perhaps reduced insight in some people with MCI may result in not realizing the need for external supports, and therefore not asking for help from others. Alternatively, in amnestic participants with greater external locus of control, perhaps the environmental cues/feedback translate to greater accuracy in their memory self-perceptions. Longitudinal analyses are needed to determine how memory self-awareness is related to future cognitive declines.
28 Social Support, APOE Genotype, and Memory Associations in a Community-Based Sample of Older Adults in Texas
- Nazareth Ortega, Abbey M Hamlin, Jordana Breton, Lauren Eisenstat, Joaquin Urquiza-Perez, Alexandra L. Clark
-
- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 441-442
-
- Article
-
- You have access Access
- Export citation
-
Objective:
The apolipoprotein E (APOE) gene has been identified as a major risk factor for the development of Alzheimer’s disease in late life. Research has shown that APOE e4 allele carriers demonstrate poorer memory performance and accelerated cognitive decline relative to non-carriers, and there is a need to identify potential factors of resiliency against the negative effects of e4 on cognition. Social support may represent one potential mechanism given that higher levels of social support have been linked to better cognitive and functional outcomes in older adults. Thus, the current study sought to examine whether social support moderates the relationship between APOE e4 status and subjective and objective memory performance in a large community-based sample of Hispanic/Latino (H/L) and Non-Hispanic White (NHW) older adults residing in Texas.
Participants and Methods:Participants included 1,564 (H/L = 808, NHW = 756) older adults (mean age = 66.36±8.68) without dementia that had enrolled in the Health and Aging Brain Study-Health Disparities. Participants completed study questionnaires and a comprehensive neuropsychological battery. Apolipoprotein e4 status (e4 carriers vs. non-carriers) was determined by possession of at least one e4 allele. Perceived social support was measured using the total score from the abbreviated 12-item version of the Interpersonal Support Evaluation List. Objective memory performance was assessed using a z-score composite of Story A and B from the Weschler Memory Scale (WMS)-III and immediate and delayed recall trials from the Spanish-English Verbal Learning Test. Subjective memory was assessed using the total score from the Subject Memory Complaints Questionnaire. Race stratified multiple linear regression models, controlling for age, sex, and years of education, examined APOE e4 positivity x social support interactions on subjective and objective memory performance.
Results:There was a significant APOE e4 genotype x social support interaction on objective memory performance (ß = -1.10, p = 0.003) in H/Ls such that higher levels of social support were associated with better memory performance in non-e4 carriers (ß = 0.14, p < .001), but not in e4 carriers (ß = -0.13, p = 0.9). In contrast, no significant APOE e4 status x social support interaction was observed on subjective memory (ß = -0.39, p = 0.35) in H/Ls. Finally, results revealed no significant APOE e4 genotype x social support interactions on subjective memory (ß = 0.14 p = 0.77) or objective memory (ß = 0.67, p = 0.11) performance in NHWs. Conclusions: Findings revealed that social support did not mitigate against the negative effects of e4 on subjective and objective memory performance in H/Ls or NHWs. However, results demonstrate that higher levels of social support are associated with better objective, but not subjective memory performance in H/Ls without the e4 genotype. These findings suggest that social support may protect against cognitive decline and enhance cognitive reserve in non-e4 carriers. Future studies should explore other potential factors of resiliency (e.g., diet, exercise) and examine the association between genetic risk and social support on neural markers (e.g., cortical thinning, hippocampal atrophy).
Radio continuum from the most massive early-type galaxies detected with ASKAP RACS
- Michael J.I. Brown, Teagan A. Clarke, Andrew M. Hopkins, Ray P. Norris, T.H. Jarrett
-
- Journal:
- Publications of the Astronomical Society of Australia / Volume 41 / 2024
- Published online by Cambridge University Press:
- 15 December 2023, e004
-
- Article
-
- You have access Access
- Open access
- HTML
- Export citation
-
All very massive early-type galaxies contain supermassive blackholes, but are these blackholes all sufficiently active to produce detectable radio continuum sources? We have used the 887.5 MHz Rapid ASKAP Continuum Survey DR1 to measure the radio emission from morphological early-type galaxies brighter than $K_S=9.5$ selected from the 2MASS Redshift Survey, HyperLEDA, and RC3. In line with previous studies, we find median radio power increases with infrared luminosity, with $P_{1.4} \propto L_K^{2.2}$, although the scatter about this relation spans several orders of magnitude. All 40 of the $M_K<-25.7$ early-type galaxies in our sample have measured radio flux densities that are more than $2\sigma$ above the background noise, with $1.4\,{\rm GHz}$ radio powers spanning ${\sim} 3 \times 10^{20}$ to ${\sim} 3\times 10^{25}\,{\rm W/Hz^{-1}}$. Cross-matching our sample with integral field spectroscopy of early-type galaxies reveals that the most powerful radio sources preferentially reside in galaxies with relatively low angular momentum (i.e. slow rotators). While the infrared colours of most galaxies in our early-type sample are consistent with passive galaxies with negligible star formation and the radio emission produced by active galactic nuclei or AGN remnants, very low levels of star formation could power the weakest radio sources with little effect on many other star formation rate tracers.
From Mind to Matter: Patterns of Innovation in the Archaeological Record and the Ecology of Social Learning
- Kathryn Demps, Nicole M. Herzog, Matt Clark
-
- Journal:
- American Antiquity / Volume 89 / Issue 1 / January 2024
- Published online by Cambridge University Press:
- 12 December 2023, pp. 19-36
- Print publication:
- January 2024
-
- Article
-
- You have access Access
- Open access
- HTML
- Export citation
-
Archaeology and cultural evolution theory both predict that environmental variation and population size drive the likelihood of inventions (via individual learning) and their conversion to population-wide innovations (via social uptake). We use the case study of the adoption of the bow and arrow in the Great Basin to infer how patterns of cultural variation, invention, and innovation affect investment in new technologies over time and the conditions under which we could predict cultural innovation to occur. Using an agent-based simulation to investigate the conditions that manifest in the innovation of technology, we find the following: (1) increasing ecological variation results in a greater reliance on individual learning, even when this decreases average fitness due to the costs of learning; (2) decreasing population size increases variability in the types of learning strategies that individuals use; among smaller populations drift-like processes may contribute to randomization in interpopulation cultural diffusion; (3) increasing the mutation rate affects the variability in learning patterns at different rates of environmental variation; and (4) increasing selection pressure increases the reliance on social learning. We provide an open-source R script for the model and encourage others to use it to test additional hypotheses.