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Alcohol milestones and internalizing, externalizing, and executive function: longitudinal and polygenic score associations
- Sarah E. Paul, David A.A. Baranger, Emma C. Johnson, Joshua J. Jackson, Aaron J. Gorelik, Alex P. Miller, Alexander S. Hatoum, Wesley K. Thompson, Michael Strube, Danielle M. Dick, Chella Kamarajan, John R. Kramer, Martin H. Plawecki, Grace Chan, Andrey P. Anokhin, David B. Chorlian, Sivan Kinreich, Jacquelyn L. Meyers, Bernice Porjesz, Howard J. Edenberg, Arpana Agrawal, Kathleen K. Bucholz, Ryan Bogdan
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- Journal:
- Psychological Medicine , First View
- Published online by Cambridge University Press:
- 09 May 2024, pp. 1-14
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Background
Although the link between alcohol involvement and behavioral phenotypes (e.g. impulsivity, negative affect, executive function [EF]) is well-established, the directionality of these associations, specificity to stages of alcohol involvement, and extent of shared genetic liability remain unclear. We estimate longitudinal associations between transitions among alcohol milestones, behavioral phenotypes, and indices of genetic risk.
MethodsData came from the Collaborative Study on the Genetics of Alcoholism (n = 3681; ages 11–36). Alcohol transitions (first: drink, intoxication, alcohol use disorder [AUD] symptom, AUD diagnosis), internalizing, and externalizing phenotypes came from the Semi-Structured Assessment for the Genetics of Alcoholism. EF was measured with the Tower of London and Visual Span Tasks. Polygenic scores (PGS) were computed for alcohol-related and behavioral phenotypes. Cox models estimated associations among PGS, behavior, and alcohol milestones.
ResultsExternalizing phenotypes (e.g. conduct disorder symptoms) were associated with future initiation and drinking problems (hazard ratio (HR)⩾1.16). Internalizing (e.g. social anxiety) was associated with hazards for progression from first drink to severe AUD (HR⩾1.55). Initiation and AUD were associated with increased hazards for later depressive symptoms and suicidal ideation (HR⩾1.38), and initiation was associated with increased hazards for future conduct symptoms (HR = 1.60). EF was not associated with alcohol transitions. Drinks per week PGS was linked with increased hazards for alcohol transitions (HR⩾1.06). Problematic alcohol use PGS increased hazards for suicidal ideation (HR = 1.20).
ConclusionsBehavioral markers of addiction vulnerability precede and follow alcohol transitions, highlighting dynamic, bidirectional relationships between behavior and emerging addiction.
ADVANCING ANTARCTIC SEDIMENT CHRONOLOGY THROUGH COMBINED RAMPED PYROLYSIS OXIDATION AND PYROLYSIS-GC-MS
- Catherine E Ginnane, Jocelyn C Turnbull, Sebastian Naeher, Brad E Rosenheim, Ryan A Venturelli, Andy M Phillips, Simon Reeve, Jeremy Parry-Thompson, Albert Zondervan, Richard H Levy, Kyu-Cheul Yoo, Gavin Dunbar, Theo Calkin, Carlota Escutia, Julia Gutierrez Pastor
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- Journal:
- Radiocarbon , First View
- Published online by Cambridge University Press:
- 08 February 2024, pp. 1-20
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Radiocarbon (14C) dating of sediment deposition around Antarctica is often challenging due to heterogeneity in sources and ages of organic carbon in the sediment. Chemical and thermochemical techniques have been used to separate organic carbon when microfossils are not present. These techniques generally improve on bulk sediment dates, but they necessitate assumptions about the age spectra of specific molecules or compound classes and about the chemical heterogeneity of thermochemical separations. To address this, the Rafter Radiocarbon Laboratory has established parallel ramped pyrolysis oxidation (RPO) and ramped pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) systems to thermochemically separate distinct carbon fractions, diagnose the chemical composition of each fraction, and target suitable RPO fractions for radiocarbon dating. Three case studies of sediment taken from locations around Antarctica are presented to demonstrate the implementation of combined RPO-AMS and Py-GC-MS to provide more robust age determination in detrital sediment stratigraphy. These three depositional environments are good examples of analytical and interpretive challenges related to oceanographic conditions, carbon sources, and other factors. Using parallel RPO-AMS and Py-GC-MS analyses, we reduce the number of radiocarbon measurements required, minimize run times, provide context for unexpected 14C ages, and better support interpretations of radiocarbon measurements in the context of environmental reconstruction.
4 Assessing Visuospatial Skills in Parkinson’s Disease Using the Identi-Fi
- AnneMarie Teti, Ryan C. Thompson, Grant G. Moncrief, Robert M. Roth
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 690-691
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Objective:
Patients with Parkinson’s disease (PD) commonly show deficits on tests of visuospatial functioning. The Identi-Fi is a new measure of visual organization and recognition composed of two components. The Visual Recognition (VR) subtest asks persons to identify an object that has been broken its pieces and rearranged, akin to the Hooper Visual Organization Test, but using updated and colorful pictures. The Visual Matching (VM) subtest involves showing the same stimuli, but the examinee must select the correct response from among five choices (1 correct and 4 foils), placing greater demand on visuospatial discrimination. Together, the two subtests comprise the Visual Organization Index (VOI), reflecting overall visual processing and organization ability. The present study examined performance on the Identi-Fi in patients with PD and its association with other aspects of cognition.
Participants and Methods:Participants were 23 patients with PD (95% male; mean age = 69.7 years [SD = 7.8], range = 47-79) and 12 patients with cognitive concerns (CC) who were intact on neuropsychological testing (excluding consideration of Identi-Fi scores; 50% male, mean age = 71.08 [SD = 6.27], range = 60-78) seen for a neuropsychological evaluation at a large Northeastern medical center. As part of a larger battery, patients completed the Identi-Fi, Trail Making Test (TMT), Category Fluency, Test of Premorbid Functioning (TOPF), and Brief Visuospatial Memory Test, Revised (BVMT-R).
Results:The PD group performed significantly worse than the CC group on VR and VM, as well as VOI, of the Identi-Fi (p < .001). Within the PD group, poorer VR, VM, and VOI performance was associated with lower scores on the TOPF (p < .05), BVMT-R learning (p < .05) and delayed recall (p < .05), as well as TMT Parts A and B (p < .05). VR was significantly correlated with Category Fluency (p < .05), while a trend was seen for the association between VOI and Category Fluency (p = .094).
Conclusions:Identi-Fi performance was worse in the PD group than the CC group, which is consistent with prior research indicating that visuospatial processing is often abnormal in patients with PD. Furthermore, findings indicate that poorer performance on the Identi-Fi in the PD group is associated with poorer cognitive functioning in other domains (i.e., visuospatial learning and memory, processing speed, cognitive flexibility, and semantic fluency), as well as lower premorbid intellectual functioning. While these findings suggest that the Identi-Fi is useful in identifying visuospatial dysfunction in PD, findings should be interpreted with caution given the small sample sizes and uneven gender distribution
62 Cognitive Functioning and Non-Cognitive Symptoms in Post-Acute COVID-19 Syndrome
- Melissa M Gardner, Ryan C Thompson, Grant G Moncrief, Robert M Roth
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 58-59
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Objective:
Patients with Post-Acute COVID Syndrome (PACS) are reported to commonly experience a variety of cognitive, physical, and neuropsychiatric symptoms well beyond the acute phase of the illness. Notably, concerns involving mood, fatigue, and physical symptoms (e.g., pain, headaches) following COVID-19 appears to be especially prevalent. It is unclear, however, the extent to which such symptoms are associated with cognitive problems in patients with PACS. In the present study, we examined the prevalence of cognitive impairment in a sample of patients with PACS, as well as the relationship between cognitive functioning and several non-cognitive symptoms.
Participants and Methods:Participants were 38 patients with PACS [71.1% female; mean age = 48.03 years (SD = 11.60) and years of education = 15.26 years (SD = 2.60)] seen for a neuropsychological evaluation at a large Northeastern medical center at least three months from the time of COVID-19 diagnosis (per PCR test). As part of a larger battery, patients completed the Hopkins Verbal Learning Test- Revised (HVLT, learning and delayed recall), Trail Making Test (TMT; time to complete parts A and B), Controlled Oral Word Association Test (COWAT total correct), and Animals (total correct). They also were administered the Chalder Fatigue Scale-11 (CFS-11), Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), and Patient Health Questionnaire (PHQ-15). The percentage of patients with scores in the impaired range (z < -1.5) on cognitive tests was determined. Correlations between cognitive and non-cognitive measures were also examined.
Results:The most frequent impairment was seen for COWAT (21.2%), followed by TMT-A and TMT-B (both 13.9%), then category fluency (9.1%). No patients were impaired on HVLT-R Learning and only one (4%) for HVLT-R Delayed Recall. Overall, the sample endorsed considerable depression, anxiety, fatigue, as well as physical symptoms. Greater fatigue was associated with worse verbal learning, processing speed, cognitive flexibility, and verbal fluency (letter and category). Worse physical symptom severity was related to poorer verbal delayed recall and cognitive flexibility. Greater anxiety was also associated with worse cognitive flexibility, while more severe depression was related to poorer category fluency.
Conclusions:In our sample of patients with PACS, seen for evaluation several months since contracting COVID-19, phonemic fluency was the most common cognitive impairment, though less than a quarter were impaired on any given cognitive test. Importantly, several associations were observed between cognitive test performance and non-cognitive symptoms commonly endorsed by patients with PACS. These findings highlight the importance of assessing multiple factors potentially contributing to cognitive impairment in these patients. Interventions designed to address such symptoms may be helpful in ameliorating cognitive functioning in those with PACS.
90 Self-Rated Executive Dysfunction in Older Adults with Subjective Cognitive Dysfunction and Mild Cognitive Impairment
- Ryan C Thompson, Melissa M Gardner, Grant G Moncrief, Robert M Roth
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 290-291
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Objective:
Mild cognitive impairment (MCI) is characterized by subjective and objective memory concerns, though additional cognitive concerns are commonly reported, including changes in executive functions (EF). Rabin et al. (2006) showed that a sample of research participants with MCI endorsed problems with their EFs, especially working memory. Similarly, those with subjective cognitive dysfunction (SCD) also reported greater difficulty with aspects of their EF than a healthy comparison sample of older adults (HC). In the present study, we investigated subjective EF in clinical samples of older adults with MCI or SCD, which represents a more naturalistic sample relative to a research sample. Furthermore, we evaluated whether subjective EF varied in these groups depending on whether patients were "young-old" versus "old-old" given prior research indicating objective cognitive differences between these age groups.
Participants and Methods:Participants were 135 older adults (53 MCI, 52 SCD, and 30 HC) matched for age (p = .116) and education (p = .863). Dichotomous categorization of age used the sample median (72 years) as cutoff score with 72 participants in the young-old group (mean age = 65.8 ± 4.7 years) and 63 in the old-old group (mean age = 78.1 ± 3.7 years). Participants completed the Behavior Rating Inventory of Executive Function-Adult (BRIEF-A), assessing executive functions in everyday life over the past month. The BRIEF-A yields an overall score (Global Executive Composite [GEC]) composed of two index scores (Behavioral Regulation Index [BRI] and Metacognition Index [MI]) and nine clinical scales (Inhibit, Shift, Emotional Control, Self-Monitor, Initiate, Working Memory, Plan/Organize, Task Monitor, and Organization of Materials). A diagnosis by age-group multivariate analysis of variance (MANOVA) with post-hoc comparisons for diagnosis using a Tukey HSD correction was conducted using SPSS Version 24.
Results:MCI and SCD groups endorsed worse EF on all three index scores (ps < .005) and all nine clinical scales (ps < .05) relative to the HC group, and the MCI group reported worse initiation relative to the SCD group. Additionally, worse executive functions on all three index scores (ps < .05) and four clinical scales (ps < .05; emotional control, self-monitoring, planning/organization, and task monitoring) were reported by the young-old group relative to the old-old group. No diagnosis by age-group interactions were observed.
Conclusions:Problems with aspects of EF were endorsed by older adults with MCI and SCD compared to HCs across all indices and clinical scales; however, only initiation was reported to be worse in MCI than those with SCD. Additionally, the young-old group endorsed having worse EF than the old-old group across BRIEF-A indices and several more specific aspects of EF, without a moderating effect of diagnosis. These findings highlight the importance of assessing subjective EF in older adults, as they may be early indicators of cognitive change, prior to objective evidence of cognitive decline. Furthermore, results also point to differences in how the young-old and old-old perceive their EF in everyday life.
Safety of tracheal intubation in the presence of cardiac disease in paediatric ICUs
- Eleanor A. Gradidge, Adnan Bakar, David Tellez, Michael Ruppe, Sarah Tallent, Geoffrey Bird, Natasha Lavin, Anthony Lee, Vinay Nadkarni, Michelle Adu-Darko, Jesse Bain, Katherine Biagas, Aline Branca, Ryan K. Breuer, Calvin Brown III, Kris Bysani, Guillaume Emeriaud, Sandeep Gangadharan, John S. Giuliano, Jr, Joy D. Howell, Conrad Krawiec, Jan Hau Lee, Simon Li, Keith Meyer, Michael Miksa, Natalie Napolitano, Sholeen Nett, Gabrielle Nuthall, Alberto Orioles, Erin B. Owen, Margaret M. Parker, Simon Parsons, Lee A. Polikoff, Kyle Rehder, Osamu Saito, Ron C. Sanders, Jr, Asha Shenoi, Dennis W. Simon, Peter W. Skippen, Keiko Tarquinio, Anne Thompson, Iris Toedt-Pingel, Karen Walson, Akira Nishisaki, For National Emergency Airway Registry for Children (NEARKIDS) Investigators and Pediatric Acute Lung Injury and Sepsis Investigators (PALISI)
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- Journal:
- Cardiology in the Young / Volume 28 / Issue 7 / July 2018
- Published online by Cambridge University Press:
- 25 April 2018, pp. 928-937
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Introduction
Children with CHD and acquired heart disease have unique, high-risk physiology. They may have a higher risk of adverse tracheal-intubation-associated events, as compared with children with non-cardiac disease.
Materials and methodsWe sought to evaluate the occurrence of adverse tracheal-intubation-associated events in children with cardiac disease compared to children with non-cardiac disease. A retrospective analysis of tracheal intubations from 38 international paediatric ICUs was performed using the National Emergency Airway Registry for Children (NEAR4KIDS) quality improvement registry. The primary outcome was the occurrence of any tracheal-intubation-associated event. Secondary outcomes included the occurrence of severe tracheal-intubation-associated events, multiple intubation attempts, and oxygen desaturation.
ResultsA total of 8851 intubations were reported between July, 2012 and March, 2016. Cardiac patients were younger, more likely to have haemodynamic instability, and less likely to have respiratory failure as an indication. The overall frequency of tracheal-intubation-associated events was not different (cardiac: 17% versus non-cardiac: 16%, p=0.13), nor was the rate of severe tracheal-intubation-associated events (cardiac: 7% versus non-cardiac: 6%, p=0.11). Tracheal-intubation-associated cardiac arrest occurred more often in cardiac patients (2.80 versus 1.28%; p<0.001), even after adjusting for patient and provider differences (adjusted odds ratio 1.79; p=0.03). Multiple intubation attempts occurred less often in cardiac patients (p=0.04), and oxygen desaturations occurred more often, even after excluding patients with cyanotic heart disease.
ConclusionsThe overall incidence of adverse tracheal-intubation-associated events in cardiac patients was not different from that in non-cardiac patients. However, the presence of a cardiac diagnosis was associated with a higher occurrence of both tracheal-intubation-associated cardiac arrest and oxygen desaturation.
Contributors
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- By Lenard A. Adler, Pinky Agarwal, Rehan Ahmed, Jagga Rao Alluri, Fawaz Al-Mufti, Samuel Alperin, Michael Amoashiy, Michael Andary, David J. Anschel, Padmaja Aradhya, Vandana Aspen, Esther Baldinger, Jee Bang, George D. Baquis, John J. Barry, Jason J. S. Barton, Julius Bazan, Amanda R. Bedford, Marlene Behrmann, Lourdes Bello-Espinosa, Ajay Berdia, Alan R. Berger, Mark Beyer, Don C. Bienfang, Kevin M. Biglan, Thomas M. Boes, Paul W. Brazis, Jonathan L. Brisman, Jeffrey A. Brown, Scott E. Brown, Ryan R. Byrne, Rina Caprarella, Casey A. Chamberlain, Wan-Tsu W. Chang, Grace M. Charles, Jasvinder Chawla, David Clark, Todd J. Cohen, Joe Colombo, Howard Crystal, Vladimir Dadashev, Sarita B. Dave, Jean Robert Desrouleaux, Richard L. Doty, Robert Duarte, Jeffrey S. Durmer, Christyn M. Edmundson, Eric R. Eggenberger, Steven Ender, Noam Epstein, Alberto J. Espay, Alan B. Ettinger, Niloofar (Nelly) Faghani, Amtul Farheen, Edward Firouztale, Rod Foroozan, Anne L. Foundas, David Elliot Friedman, Deborah I. Friedman, Steven J. Frucht, Oded Gerber, Tal Gilboa, Martin Gizzi, Teneille G. Gofton, Louis J. Goodrich, Malcolm H. Gottesman, Varda Gross-Tsur, Deepak Grover, David A. Gudis, John J. Halperin, Maxim D. Hammer, Andrew R. Harrison, L. Anne Hayman, Galen V. Henderson, Steven Herskovitz, Caitlin Hoffman, Laryssa A. Huryn, Andres M. Kanner, Gary P. Kaplan, Bashar Katirji, Kenneth R. Kaufman, Annie Killoran, Nina Kirz, Gad E. Klein, Danielle G. Koby, Christopher P. Kogut, W. Curt LaFrance, Patrick J.M. Lavin, Susan W. Law, James L. Levenson, Richard B. Lipton, Glenn Lopate, Daniel J. Luciano, Reema Maindiratta, Robert M. Mallery, Georgios Manousakis, Alan Mazurek, Luis J. Mejico, Dragana Micic, Ali Mokhtarzadeh, Walter J. Molofsky, Heather E. Moss, Mark L. Moster, Manpreet Multani, Siddhartha Nadkarni, George C. Newman, Rolla Nuoman, Paul A. Nyquist, Gaia Donata Oggioni, Odi Oguh, Denis Ostrovskiy, Kristina Y. Pao, Juwen Park, Anastas F. Pass, Victoria S. Pelak, Jeffrey Peterson, John Pile-Spellman, Misha L. Pless, Gregory M. Pontone, Aparna M. Prabhu, Michael T. Pulley, Philip Ragone, Prajwal Rajappa, Venkat Ramani, Sindhu Ramchandren, Ritesh A. Ramdhani, Ramses Ribot, Heidi D. Riney, Diana Rojas-Soto, Michael Ronthal, Daniel M. Rosenbaum, David B. Rosenfield, Durga Roy, Michael J. Ruckenstein, Max C. Rudansky, Eva Sahay, Friedhelm Sandbrink, Jade S. Schiffman, Angela Scicutella, Maroun T. Semaan, Robert C. Sergott, Aashit K. Shah, David M. Shaw, Amit M. Shelat, Claire A. Sheldon, Anant M. Shenoy, Yelizaveta Sher, Jessica A. Shields, Tanya Simuni, Rajpaul Singh, Eric E. Smouha, David Solomon, Mehri Songhorian, Steven A. Sparr, Egilius L. H. Spierings, Eve G. Spratt, Beth Stein, S.H. Subramony, Rosa Ana Tang, Cara Tannenbaum, Hakan Tekeli, Amanda J. Thompson, Michael J. Thorpy, Matthew J. Thurtell, Pedro J. Torrico, Ira M. Turner, Scott Uretsky, Ruth H. Walker, Deborah M. Weisbrot, Michael A. Williams, Jacques Winter, Randall J. Wright, Jay Elliot Yasen, Shicong Ye, G. Bryan Young, Huiying Yu, Ryan J. Zehnder
- Edited by Alan B. Ettinger, Albert Einstein College of Medicine, New York, Deborah M. Weisbrot, State University of New York, Stony Brook
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- Book:
- Neurologic Differential Diagnosis
- Published online:
- 05 June 2014
- Print publication:
- 17 April 2014, pp xi-xx
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Contributors
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- By Douglas L. Arnold, Laura J. Balcer, Amit Bar-Or, Sergio E. Baranzini, Frederik Barkhof, Robert A. Bermel, Francois A. Bethoux, Dennis N. Bourdette, Richard K. Burt, Peter A. Calabresi, Zografos Caramanos, Tanuja Chitnis, Stacey S. Cofield, Jeffrey A. Cohen, Nadine Cohen, Alasdair J. Coles, Devon Conway, Stuart D. Cook, Gary R. Cutter, Peter J. Darlington, Ann Dodds-Frerichs, Ranjan Dutta, Gilles Edan, Michelle Fabian, Franz Fazekas, Massimo Filippi, Elizabeth Fisher, Paulo Fontoura, Corey C. Ford, Robert J. Fox, Natasha Frost, Alex Z. Fu, Siegrid Fuchs, Kazuo Fujihara, Kristin M. Galetta, Jeroen J.G. Geurts, Gavin Giovannoni, Nada Gligorov, Ralf Gold, Andrew D. Goodman, Myla D. Goldman, Jenny Guerre, Stephen L. Hauser, Peter B. Imrey, Douglas R. Jeffery, Stephen E. Jones, Adam I. Kaplin, Michael W. Kattan, B. Mark Keegan, Kyle C. Kern, Zhaleh Khaleeli, Samia J. Khoury, Joep Killestein, Soo Hyun Kim, R. Philip Kinkel, Stephen C. Krieger, Lauren B. Krupp, Emmanuelle Le Page, David Leppert, Scott Litwiller, Fred D. Lublin, Henry F. McFarland, Joseph C. McGowan, Don Mahad, Jahangir Maleki, Ruth Ann Marrie, Paul M. Matthews, Francesca Milanetti, Aaron E. Miller, Deborah M. Miller, Xavier Montalban, Charity J. Morgan, Ichiro Nakashima, Sridar Narayanan, Avindra Nath, Paul W. O’Connor, Jorge R. Oksenberg, A. John Petkau, Michael D. Phillips, J. Theodore Phillips, Tammy Phinney, Sean J. Pittock, Sarah M. Planchon, Chris H. Polman, Alexander Rae-Grant, Stephen M. Rao, Stephen C. Reingold, Maria A. Rocca, Richard A. Rudick, Amber R. Salter, Paula Sandler, Jaume Sastre-Garriga, John R. Scagnelli, Dana J. Serafin, Lynne Shinto, Nancy L. Sicotte, Jack H. Simon, Per Soelberg Sørensen, Ryan E. Stagg, James M. Stankiewicz, Lael A. Stone, Amy Sullivan, Matthew Sutliff, Jessica Szpak, Alan J. Thompson, Bruce D. Trapp, Helen Tremlett, Maria Trojano, Orla Tuohy, Rhonda R. Voskuhl, Marc K. Walton, Mike P. Wattjes, Emmanuelle Waubant, Martin S. Weber, Howard L Weiner, Brian G. Weinshenker, Bianca Weinstock-Guttman, Jeffrey L. Winters, Jerry S. Wolinsky, Vijayshree Yadav, E. Ann Yeh, Scott S. Zamvil
- Edited by Jeffrey A. Cohen, Richard A. Rudick
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- Book:
- Multiple Sclerosis Therapeutics
- Published online:
- 05 December 2011
- Print publication:
- 20 October 2011, pp viii-xii
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The effect of mass ratio and tether length on the flow around a tethered cylinder
- K. RYAN, M. C. THOMPSON, K. HOURIGAN
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- Journal:
- Journal of Fluid Mechanics / Volume 591 / 25 November 2007
- Published online by Cambridge University Press:
- 30 October 2007, pp. 117-144
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A tethered cylinder may be considered an extension of the widely studied problem of a hydro-elastically mounted cylinder. Here we numerically investigate the flow past a positively buoyant tethered cylinder for a range of mass ratios and tether length ratios at a Reynolds number Re = 200. The results are found to be qualitatively similar to related experimental work performed at significantly higher Reynolds numbers. Two important findings are related in this paper. First, we find that the action of the tethered cylinder oscillating at an angle to the flow induces a mean lift coefficient. Second, a critical mass ratio (m*crit) is found below which large-amplitude oscillations are noted, similar to that previously reported for the case of a hydro-elastically mounted cylinder. For short tether lengths, (m*crit) is significantly greater than that found for a hydro-elastically mounted cylinder. As the tether length increases, the (m*crit) decreases and asymptotes to that of a hydro-elastically mounted cylinder as the tether length approaches infinity.
Three-dimensional transition in the wake of bluff elongated cylinders
- K. RYAN, M. C. THOMPSON, K. HOURIGAN
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- Journal:
- Journal of Fluid Mechanics / Volume 538 / 10 September 2005
- Published online by Cambridge University Press:
- 17 August 2005, pp. 1-29
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Despite little supporting evidence, there appears to be an implicit assumption that the wakes of two-dimensional bluff bodies undergo transition to three-dimensional flow and eventually turbulence, through the same sequence of transitions as observed for a circular cylinder wake. Previous studies of a square cylinder wake support this assumption. In this paper, the transition to three-dimensional wake flow is examined for an elongated cylinder with an aerodynamic leading edge and square trailing edge. The three-dimensional instability modes are determined as a function of aspect ratio ($\hbox{\it AR}\,{=}\,$length to width). Floquet analysis reveals that three distinct instabilities occur. These are referred to as Modes A, B$^\prime$ and S$^\prime$ through analogy with the modes for circular and square cylinders. For aspect ratios less than approximately 7.5, Mode A is the most unstable mode. For aspect ratios greater than this, the most unstable mode switches to Mode B$^\prime$. This has the same spatio-temporal symmetry as Mode B for a circular cylinder, but a spanwise wavelength and near-wake features more in common with Mode S for a square cylinder. The dominant wavelength for this mode is approximately two cylinder thicknesses, much longer than for Mode B for a circular cylinder. It is found that the critical Reynolds number for the onset of the Mode A instability varies approximately with the square root of the aspect ratio. On the other hand, the critical Reynolds number for Mode B$^\prime$ is almost independent of aspect ratio. For large aspect ratios, the separation in Reynolds number between the critical Reynolds numbers is substantial; for instance, for $\hbox{\it AR}\,{=}\,17.5$, these values are approximately 450 and 700. In fact, for this aspect ratio, the third instability mode, Mode S$^\prime$, is more unstable than Mode A. These results suggest that the transition scenario for elongated bluff bodies may be distinctly different to short bodies such as circular or square cylinders. At the very least, the dominant spanwise wavelength in the turbulent wake is likely to be much longer than that for a circular cylinder wake. In addition, the reversal of the ordering of occurrence of the two modes with the different spatial symmetries is likely to affect the development of spatio-temporal chaos as a precursor to fully turbulent flow.
In conjunction with prior work, the current results indicate that nearly all three-dimensional instabilities of the vortex street can be identified as one of only a handful of transition modes.
Genotyping of Cryptosporidium spp. isolated from human stool samples in Switzerland
- R. FRETZ, P. SVOBODA, U. M. RYAN, R. C. A. THOMPSON, M. TANNER, A. BAUMGARTNER
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- Journal:
- Epidemiology & Infection / Volume 131 / Issue 1 / August 2003
- Published online by Cambridge University Press:
- 23 September 2003, pp. 663-667
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In a study to estimate the frequency of Cryptosporidium infections in Switzerland, stool samples from patients found to be positive for Cryptosporidium spp. by modified Ziehl–Neelson staining and fluorescence microscopy were used for genotyping experiments. With 9 of 12 samples, DNA extraction and subsequent genotyping was successful. All Cryptosporidium-isolates belonged to the bovine genotype. In one stool sample, two strains of Cryptosporidium were demonstrated, suggesting a mixed infection. In comparison with reference strains from calves, one of the isolates showed a full sequence identity and the other a similarity of 97·5%. The fact that only bovine genotypes were detected suggests, that cryptosporidiosis must primarily be considered as a zoonotic disease in Switzerland. This is in contrast to other countries, where the human genotype of C. parvum was shown to dominate the epidemiological situation. The results of our study are supported by the previous finding, that two of the analysed strains originated from patients who used to consume raw milk or raw cream, a known risk factor for cryptosporidiosis.
A molecular phylogeny of nuclear and mitochondrial sequences in Hymenolepis nana (Cestoda) supports the existence of a cryptic species
- M. G. MACNISH, U. M. MORGAN-RYAN, P. T. MONIS, J. M. BEHNKE, R. C. A. THOMPSON
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- Journal:
- Parasitology / Volume 125 / Issue 6 / June 2002
- Published online by Cambridge University Press:
- 11 February 2003, pp. 567-575
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Since isolates of Hymenolepis nana infecting humans and rodents are morphologically indistinguishable, the only way they can be reliably identified is by comparing the parasite in each host using molecular tools. In the current study, isolates of H. nana from rodent and human hosts from a broad geographical range were sequenced at the ribosomal first internal transcribed spacer (ITS1), the mitochondrial cytochrome c oxidase subunit 1 (C01) gene and the nuclear paramyosin gene loci.
Nucleotide sequence data published here have been submitted to GenBank™ and are available under accession numbers AF461124 and AF461125 (18S–28S); AY121842 and AY121843 (cytochrome c oxidase 1); AY1844 and AY121845 (paramyosin). Twenty-three isolates of H. nana were sequenced at the ITS1 locus and this confirmed the existence of spacers which, although similar in length (approximately 646 bp), differed in their primary sequences which led to the separation of the isolates into 2 clusters when analysed phylogenetically. This sequence variation was not, however, related to the host of origin of the isolate, thus was not a marker of genetic distinction between H. nana from rodents and humans. Sequencing of a 444 bp fragment of the mitochondrial cytochrome c oxidase 1 gene (C01) in 9 isolates of H. nana from rodents and 6 from humans identified a phylogenetically supported genetic divergence of approximately 5% between some mouse and human isolates. This suggests that H. nana is a species complex, or ‘cryptic’ species (=morphologically identical yet genetically distinct). A small segment of the nuclear gene, paramyosin, (625 bp or 840 bp) was sequenced in 4 mouse and 3 human isolates of H. nana. However, this gene did not provide the level of heterogeneity required to distinguish between isolates from rodent and human hosts. From the results obtained from faster evolving genes, and the epidemiological evidence, we believe that the life-cycle of H. nana that exists in the north-west of Western Australia is likely to involve mainly ‘human to human’ transmission.
Molecular and morphological characterization of Echinococcus granulosus of human and animal origin in Iran
- M. FASIHI HARANDI, R. P. HOBBS, P. J. ADAMS, I. MOBEDI, U. M. MORGAN-RYAN, R. C. A. THOMPSON
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- Journal:
- Parasitology / Volume 125 / Issue 4 / October 2002
- Published online by Cambridge University Press:
- 16 January 2003, pp. 367-373
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Iran is an important endemic focus of cystic hydatid disease (CHD) where several species of intermediate host are commonly infected with Echinococcus granulosus. Isolates of E. granulosus were collected from humans and other animals from different geographical areas of Iran and characterized using both DNA (PCR-RFLP of ITS1) and morphological criteria (metacestode rostellar hook dimensions). The sheep and camel strains/genotypes were shown to occur in Iran. The sheep strain was shown to be the most common genotype of E. granulosus affecting sheep, cattle, goats and occasionally camels. The majority of camels were infected with the camel genotype as were 3 of 33 human cases. This is the first time that cases of CHD in humans have been identified in an area where a transmission cycle for the camel genotype exists. In addition, the camel genotype was found to cause infection in both sheep and cattle. Results also demonstrated that both sheep and camel strains can be readily differentiated on the basis of hook morphology alone.
Characterization of Nanoparticle Films and Structures Produced by Hypersonic Plasma Particle Deposition
- Christopher R. Perrey, Ryan Thompson, C. Barry Carter, Ashok Gidwani, Rajesh Mukherjee, Thierry Renault, P. H. McMurry, J. V. R. Heberlein, S. L. Girshick
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- Journal:
- MRS Online Proceedings Library Archive / Volume 740 / 2002
- Published online by Cambridge University Press:
- 11 February 2011, I4.6
- Print publication:
- 2002
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There is great potential for the use of nanostructures in numerous applications. Investigation of nanoparticle films and structures is an important area of research for the production of nanoengineered devices. However, for these devices to become a reality, a production method that can yield high-rate synthesis of nanostructured powders is necessary. The hypersonic plasma particle deposition (HPPD) process has been shown to be capable of such high-rate production of nanoparticle films and structures. Versatile in its ability to manufacture nanoparticles of different chemistries HPPD also has the capability of in situ particle consolidation and assembly. In this study, chemically diverse films and structures have been produced by HPPD on a variety of substrates. Using novel specimen preparation techniques, these nanoparticles have been characterized by TEM. Fundamental issues of importance have been investigated for both the nanoparticle structure and the constituent nanoparticles. These issues include nanoparticle crystallinity and defect structure. The chemical homogeneity and structural characteristics of the deposition are also investigated. This application of microscopy to aid process development has resulted in insights into the nanoparticle formation process and the dynamics of the HPPD process.
Solid-State Reactions in Model Oxide Systems
- Matthew T. Johnson, Paul G. Kotula, Ryan S. Thompson, C. Barry Carter
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- Journal:
- MRS Online Proceedings Library Archive / Volume 453 / 1996
- Published online by Cambridge University Press:
- 15 February 2011, 695
- Print publication:
- 1996
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The kinetics of thin-film solid-state reactions have been investigated in two model spinel forming oxide systems, NiO/Al2O3 and MgO/Fe2O3. In the NiO/Al2O3 system, thin-films of epitactic NiO were reacted with (0001), , and orientated Al2O3 (corundum). The kinetics of the spinel forming reaction for this system were found to be linear-parabolic in nature. Additionally, it was found that the kinetics of the spinel-forming reaction varied by nearly two orders of magnitude between the fastest and slowest diffusion couples. The substrate determines the orientation of the overlayers and thereby the structure of the phase boundaries. In the MgO/Fe-oxide system, thin films of epitactic Fe oxide were reacted with {001} MgO. The kinetics of this spinel forming reaction were parabolic in nature, indicative of diffusion control. In contrast to the N1O/Al2O3 system, the movement of phase boundaries are not the step controlling the reaction rate, but rather the diffusion of one of the cations across the reaction layer. In comparing the reaction rates for the two systems the activation energy for the formation of the spinel product in the MgO/Fe-oxide system was found to be almost a factor of 4 lower in comparison to the NiO/Al2O3 system.