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11 Contributions of Cardiovascular Burden, Peripheral Inflammation, and Brain Integrity on Digital Clock Drawing Performance in Non-Demented Older Adults
- Catherine Dion, Jared J. Tanner, David J. Libon, Catherine C. Price
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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. 325-326
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Objective:
Higher cardiovascular burden and peripheral inflammation are associated with small vessel vascular disease, a predominantly dysexecutive cognitive profile, and a higher likelihood of conversion to vascular dementia. The digital clock drawing test, a digitized version of a standard neuropsychological tool, is useful in identifying cognitive dysfunction related to vascular etiology. However, little is known about the specific cognitive implications of vascular risk, peripheral inflammation, and varying levels of overall brain integrity. The current study aimed to examine the role of cardiovascular burden, peripheral inflammation, and brain integrity on digitally acquired clock drawing latency and graphomotor metrics in non-demented older adults.
Participants and Methods:The final prospectively recruited IRB-consented participant sample included 184 non-demented older adults (age: 69±6 years, education: 16±3 years, 46% female, 94% white) who completed digital clock drawing, vascular assessment, blood draw, and brain MRI. Digital clock drawing variables of interest included: total completion time (TCT), pre-first hand latency (PFHL), digit misplacement, hour hand distance from center, and clock face area (CFA). Cardiovascular burden was calculated using the revised version of the Framingham Stroke Risk Profile (FSRP-10). Peripheral inflammation was operationalized using interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor alpha (TNF-a), and high sensitivity C-reactive protein (hsCRP). The brain integrity composite was comprised of bilateral entorhinal cortex volume, bilateral ventricular volume, and whole brain leukoaraiosis.
Results:Over and above age and cognitive reserve, hierarchical regressions showed FSRP-10, inflammatory markers, and brain integrity explained an additional 13.3% of the variance in command TCT (p< 0.001), with FSRP-10 (p=0.001), IL-10 (p= 0.019), and hsCRP (p= 0.019) as the main predictors in the model. FSRP-10, inflammatory markers, and brain integrity explained an additional 11.7% of the variance in command digit misplacement (p= 0.009), with findings largely driven by FSRP-10 (p< 0.001).
Conclusions:Overall, in non-demented older adults, subtle behavioral nuances seen in digital clock drawing metrics (i.e., total completion time and digit misplacement) are partly explained by cardiovascular burden, peripheral inflammation, and brain integrity over and above age and cognitive reserve. These nuanced behaviors on digitally acquired clock drawing may associate with an emergent disease process or overall vulnerability.
Funding sources: Barber Fellowship; K07AG066813; R01 AG055337; R01 NR014810; American Psychological Foundation Dissertation Award; APA Dissertation Research Award
22 Cognitive Reserve's Relationship to Brain Burden in Parkinson's Disease Without Dementia
- Lauren E. Kenney, Jared Tanner, Samuel J. Crowley, Thomas H. Mareci, Francesca V. Lopez, Adrianna M. Ratajska, Katie Rodriguez, Rachel Schade, Joshua Gertler, Catherine C. Price, Dawn Bowers
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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. 539-540
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Objective:
Individuals with Parkinson's disease (PD) have varying trajectories of cognitive decline. One reason for this heterogeneity may be "cognitive reserve": where higher education/IQ/current mental engagement compensates for increasing brain burden (Stern et al., 2020). With few exceptions, most studies examining cognitive reserve in PD fail to include brain metrics. This study's goal was to examine whether cognitive reserve moderated the relationship between neuroimaging indices of brain burden (diffusion free water fraction and T2-weighted white matter changes) and two commonly impaired domains in PD: executive function and memory. We hypothesized cognitive reserve would mitigate the relationship between higher brain burden and worse cognitive performance.
Participants and Methods:Participants included 108 individuals with PD without dementia (age mean=67.9±6.3, education mean=16.6±2.5) who were prospectively recruited for two NIH-funded projects at the University of Florida. All received neuropsychological measures of executive function (Trails B, Stroop, Letter Fluency) and memory (delayed recall: Hopkin's Verbal Learning Test-Revised, WMS-III Logical Memory). Domain specific z-score composites were created using data from age/education matched non-PD peer controls (N=62). For the Cognitive Reserve (CR) proxy, a z-score composite included years of education, WASI-II Vocabulary, and Wechsler Test of Adult Reading. At the time of testing, participants completed multiple MRI scans (T1-weighted, diffusion, Fluid Attenuated Inversion Recovery) from which the following were extracted: 1) whole-brain free water within the white matter (a measure of microstructural integrity and neuroinflammation), 2) white matter hyperintensities/white matter total volume (WMH/WMV), and bilaterally-averaged edge weights of white matter connectivity between 3) dorsolateral prefrontal cortex and caudate and 4) entorhinal cortex and hippocampi. Separate linear regressions for each brain metric used executive function and memory composites as dependent variables; predictors were age, CR proxy, respective brain metric, and a residual centered interaction term (brain metric*CR proxy). Identical models were run in dichotomized short and long disease duration groups (median split=6 years).
Results:In all models, a lower CR proxy significantly predicted worse executive function (WMH/WMV: beta=0.49, free water: beta=0.54, frontal edge weight: beta=0.49, p's<0.001) and memory (WMH/WMV: beta=0.42, free water: beta=0.35, temporal edge weight: beta=0.39, p's <0.01). For neuroimaging metrics, higher free water significantly predicted worse executive function (beta=-0.39, p=0.002) but not memory. No other brain metrics were significant predictors of either domain. Accounting for PD duration, higher free water predicted worse executive function for those with both short (beta=-0.49, p=0.04) and long disease duration (beta=-0.48, p=0.02). Specifically in those with long disease duration, higher free water (beta=-0.57 p=0.02) and lower edge weights between entorhinal cortex and hippocampi (beta=0.30, p=0.03) predicted worse memory. Overall, no models contained significant interactions between the CR proxy and any brain metric.
Conclusions:Results replicate previous work showing that a cognitive reserve proxy relates to cognition. However, cognitive reserve did not moderate brain burden's relationship to cognition. Across the sample, greater neuroinflammation was associated with worse executive function. For those with longer disease duration, higher neuroinflammation and lower medial temporal white matter connectivity related to worse memory. Future work should examine other brain burden metrics to determine whether/how cognitive reserve influences the cognitive trajectory of PD.
56 Chronic Musculoskeletal Pain, Biobehavioral and Psychosocial Resilience Index, and Brain Age Gap
- Udell Holmes III, Jared Tanner, Brittany Addison, Kenia Rangel, Angela M Mickle, Cynthia S Garvan, Emily J Bartley, Amber K Brooks, Lai Song, Roland Staud, Burel Goodin, Roger B Fillingim, Catherine C Price, Kimberly T Sibille
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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, p. 465
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Objective:
Chronic musculoskeletal pain is associated with neurobiological, physiological, and cellular measures. Importantly, we have previously demonstrated that a biobehavioral and psychosocial resilience index appears to have a protective relationship on the same biomarkers. Less is known regarding the relationships between chronic musculoskeletal pain, protective factors, and brain aging. This study investigates the relationships between clinical pain, a resilience index, and brain age. We hypothesized that higher reported chronic pain would correlate with older appearing brains, and the resilience index will attenuate the strength of the relationship between chronic pain and brain age.
Participants and Methods:Participants were drawn from an ongoing observational multisite study and included adults with chronic pain who also reported knee pain (N = 135; age = 58.3 ± 8.1; 64% female; 49% non-Hispanic Black, 51% non-Hispanic White; education Mdn = some college; income level Mdn = $30,000 - $40,000; MoCA M = 24.27 ± 3.49). Measures included the Graded Chronic Pain Scale (GCPS), characteristic pain intensity (CPI) and disability, total pain body sites; and a cognitive screening (MoCA). The resilience index consisted of validated biobehavioral (e.g., smoking, waist/hip ratio, and active coping) and psychosocial measures (e.g., optimism, positive affect, negative affect, perceived stress, and social support). T1-weighted MRI data were obtained. Surface area metrics were calculated in FreeSurfer using the Human Connectome Project's multi-modal cortical parcellation scheme. We calculated brain age in R using previously validated and trained machine learning models. Chronological age was subtracted from predicted brain age to generate a brain age gap (BAG). With higher scores of BAG indicating predicated age is older than chronological age. Three parallel hierarchical regression models (each containing one of three pain measures) with three blocks were performed to assess the relationships between chronic pain and the resilience index in relation to BAG, adjusting for covariates. For each model, Block 1 entered the covariates, Block 2 entered a pain score, and Block 3 entered the resilience index.
Results:GCPS CPI (R2 change = .033, p = .027) and GCPS disability (R2 change = 0.038, p = 0.017) significantly predicted BAG beyond the effects of the covariates, but total pain sites (p = 0.865) did not. The resilience index was negatively correlated and a significant predictor of BAG in all three models (p < .05). With the resilience index added in Block 3, both GCPS CPI (p = .067) and GCPS disability (p = .066) measures were no longer significant in their respective models. Additionally, higher education/income (p = 0.016) and study site (p = 0.031) were also significant predictors of BAG.
Conclusions:In this sample, higher reported chronic pain correlated with older appearing brains, and higher resilience attenuated this relationship. The biobehavioral and psychosocial resilience index was associated with younger appearing brains. While our data is cross-sectional, findings are encouraging that interventions targeting both chronic pain and biobehavioral and psychosocial factors (e.g., coping strategies, positive and negative affect, smoking, and social support) might buffer brain aging. Future directions include assessing if chronic pain and resilience factors can predict brain aging over time.
Core handling, transportation and processing for the South Pole ice core (SPICEcore) project — ERRATUM
- Joseph M. Souney, Mark S. Twickler, Murat Aydin, Eric J. Steig, T. J. Fudge, Leah V. Street, Melinda R. Nicewonger, Emma C. Kahle, Jay A. Johnson, Tanner W. Kuhl, Kimberly A. Casey, John M. Fegyveresi, Richard M. Nunn, Geoffrey M. Hargreaves
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- Journal:
- Annals of Glaciology / Volume 62 / Issue 85-86 / September 2021
- Published online by Cambridge University Press:
- 17 September 2021, p. 391
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Addressing personal protective equipment (PPE) decontamination: Methylene blue and light inactivates severe acute respiratory coronavirus virus 2 (SARS-CoV-2) on N95 respirators and medical masks with maintenance of integrity and fit
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- Thomas Sean Lendvay, James Chen, Brian H. Harcourt, Florine E. M. Scholte, Ying Ling Lin, F. Selcen Kilinc-Balci, Molly M. Lamb, Kamonthip Homdayjanakul, Yi Cui, Amy Price, Belinda Heyne, Jaya Sahni, Kareem B. Kabra, Yi-Chan Lin, David Evans, Christopher N. Mores, Ken Page, Larry F. Chu, Eric Haubruge, Etienne Thiry, Louisa F. Ludwig-Begall, Constance Wielick, Tanner Clark, Thor Wagner, Emily Timm, Thomas Gallagher, Peter Faris, Nicolas Macia, Cyrus J. Mackie, Sarah M. Simmons, Susan Reader, Rebecca Malott, Karen Hope, Jan M. Davies, Sarah R. Tritsch, Lorène Dams, Hans Nauwynck, Jean-Francois Willaert, Simon De Jaeger, Lei Liao, Mervin Zhao, Jan Laperre, Olivier Jolois, Sarah J. Smit, Alpa N. Patel, Mark Mayo, Rod Parker, Vanessa Molloy-Simard, Jean-Luc Lemyre, Steven Chu, John M. Conly, May C. Chu
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 43 / Issue 7 / July 2022
- Published online by Cambridge University Press:
- 21 May 2021, pp. 876-885
- Print publication:
- July 2022
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Objective:
The coronavirus disease 2019 (COVID-19) pandemic has resulted in shortages of personal protective equipment (PPE), underscoring the urgent need for simple, efficient, and inexpensive methods to decontaminate masks and respirators exposed to severe acute respiratory coronavirus virus 2 (SARS-CoV-2). We hypothesized that methylene blue (MB) photochemical treatment, which has various clinical applications, could decontaminate PPE contaminated with coronavirus.
Design:The 2 arms of the study included (1) PPE inoculation with coronaviruses followed by MB with light (MBL) decontamination treatment and (2) PPE treatment with MBL for 5 cycles of decontamination to determine maintenance of PPE performance.
Methods:MBL treatment was used to inactivate coronaviruses on 3 N95 filtering facepiece respirator (FFR) and 2 medical mask models. We inoculated FFR and medical mask materials with 3 coronaviruses, including SARS-CoV-2, and we treated them with 10 µM MB and exposed them to 50,000 lux of white light or 12,500 lux of red light for 30 minutes. In parallel, integrity was assessed after 5 cycles of decontamination using multiple US and international test methods, and the process was compared with the FDA-authorized vaporized hydrogen peroxide plus ozone (VHP+O3) decontamination method.
Results:Overall, MBL robustly and consistently inactivated all 3 coronaviruses with 99.8% to >99.9% virus inactivation across all FFRs and medical masks tested. FFR and medical mask integrity was maintained after 5 cycles of MBL treatment, whereas 1 FFR model failed after 5 cycles of VHP+O3.
Conclusions:MBL treatment decontaminated respirators and masks by inactivating 3 tested coronaviruses without compromising integrity through 5 cycles of decontamination. MBL decontamination is effective, is low cost, and does not require specialized equipment, making it applicable in low- to high-resource settings.
Core handling, transportation and processing for the South Pole ice core (SPICEcore) project
- Joseph M. Souney, Mark S. Twickler, Murat Aydin, Eric J. Steig, T. J. Fudge, Leah V. Street, Melinda R. Nicewonger, Emma C. Kahle, Jay A. Johnson, Tanner W. Kuhl, Kimberly A. Casey, John M. Fegyveresi, Richard M. Nunn, Geoffrey M. Hargreaves
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- Annals of Glaciology / Volume 62 / Issue 84 / April 2021
- Published online by Cambridge University Press:
- 07 December 2020, pp. 118-130
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An intermediate-depth (1751 m) ice core was drilled at the South Pole between 2014 and 2016 using the newly designed US Intermediate Depth Drill. The South Pole ice core is the highest-resolution interior East Antarctic ice core record that extends into the glacial period. The methods used at the South Pole to handle and log the drilled ice, the procedures used to safely retrograde the ice back to the National Science Foundation Ice Core Facility (NSF-ICF), and the methods used to process and sample the ice at the NSF-ICF are described. The South Pole ice core exhibited minimal brittle ice, which was likely due to site characteristics and, to a lesser extent, to drill technology and core handling procedures.
Reliability and Utility of Manual and Automated Estimates of Total Intracranial Volume
- Samuel J. Crowley, Jared J. Tanner, Daniel Ramon, Nadine A. Schwab, Loren P. Hizel, Catherine C. Price
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- Journal of the International Neuropsychological Society / Volume 24 / Issue 2 / February 2018
- Published online by Cambridge University Press:
- 05 October 2017, pp. 206-211
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Objectives: Total intracranial volume (TICV) is an important control variable in brain–behavior research, yet its calculation has challenges. Manual TICV (Manual) is labor intensive, and automatic methods vary in reliability. To identify an accurate automatic approach we assessed the reliability of two FreeSurfer TICV metrics (eTIV and Brainmask) relative to manual TICV. We then assessed how these metrics alter associations between left entorhinal cortex (ERC) volume and story retention. Methods: Forty individuals with Parkinson’s disease (PD) and 40 non-PD peers completed a brain MRI and memory testing. Manual metrics were compared to FreeSurfer’s Brainmask (a skull strip mask with total volume of gray, white, and most cerebrospinal fluid) and eTIV (calculated using the transformation matrix into Talairach space). Volumes were compared with two-way interclass correlations and dice similarity indices. Associations between ERC volume and Wechsler Memory Scale-Third Edition Logical Memory retention were examined with and without correction using each TICV method. Results: Brainmask volumes were larger and eTIV volumes smaller than Manual. Both automated metrics correlated highly with Manual. All TICV metrics explained additional variance in the ERC-Memory relationship, although none were significant. Brainmask explained slightly more variance than other methods. Conclusions: Our findings suggest Brainmask is more reliable than eTIV for TICV correction in brain-behavioral research. (JINS, 2018, 24, 206–211)
Are Parkinson’s Patients More Vulnerable to the Effects of Cardiovascular Risk: A Neuroimaging and Neuropsychological Study
- Jacob D. Jones, Jared J. Tanner, Michael Okun, Catherine C. Price, Dawn Bowers
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- Journal of the International Neuropsychological Society / Volume 23 / Issue 4 / April 2017
- Published online by Cambridge University Press:
- 06 February 2017, pp. 322-331
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Objectives: This study examined whether individuals with Parkinson’s disease (PD) are at increased vulnerability for vascular-related cognitive impairment relative to controls. The underlying assumption behind this hypothesis relates to brain reserve and that both PD and vascular risk factors impair similar fronto-executive cognitive systems. Methods: The sample included 67 PD patients and 61 older controls (total N=128). Participants completed neuropsychological measures of executive functioning, processing speed, verbal delayed recall/memory, language, and auditory attention. Cardiovascular risk was assessed with the Framingham Cardiovascular Risk index. Participants underwent brain imaging (T1 and T2 FLAIR). Trained raters measured total and regional leukoaraiosis (periventricular, deep subcortical, and infracortical). Results: Hierarchical regressions revealed that more severe cardiovascular risk was related to worse executive functioning, processing speed, and delayed verbal recall in both Parkinson patients and controls. More severe cardiovascular risk was related to worse language functioning in the PD group, but not controls. In contrast, leukoaraiosis related to both cardiovascular risk and executive functioning for controls, but not the PD group. Conclusions: Overall, results revealed that PD and cardiovascular risk factors are independent risk factors for cognitive impairment. Generally, the influence of cardiovascular risk factors on cognition is similar in PD patients and controls. (JINS, 2017, 23, 322–331)
Job strain as a risk factor for clinical depression: systematic review and meta-analysis with additional individual participant data
- I. E. H. Madsen, S. T. Nyberg, L. L. Magnusson Hanson, J. E. Ferrie, K. Ahola, L. Alfredsson, G. D. Batty, J. B. Bjorner, M. Borritz, H. Burr, J.-F. Chastang, R. de Graaf, N. Dragano, M. Hamer, M. Jokela, A. Knutsson, M. Koskenvuo, A. Koskinen, C. Leineweber, I. Niedhammer, M. L. Nielsen, M. Nordin, T. Oksanen, J. H. Pejtersen, J. Pentti, I. Plaisier, P. Salo, A. Singh-Manoux, S. Suominen, M. ten Have, T. Theorell, S. Toppinen-Tanner, J. Vahtera, A. Väänänen, P. J. M. Westerholm, H. Westerlund, E. I. Fransson, K. Heikkilä, M. Virtanen, R. Rugulies, M. Kivimäki, for the IPD-Work Consortium
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- Journal:
- Psychological Medicine / Volume 47 / Issue 8 / June 2017
- Published online by Cambridge University Press:
- 26 January 2017, pp. 1342-1356
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Background
Adverse psychosocial working environments characterized by job strain (the combination of high demands and low control at work) are associated with an increased risk of depressive symptoms among employees, but evidence on clinically diagnosed depression is scarce. We examined job strain as a risk factor for clinical depression.
MethodWe identified published cohort studies from a systematic literature search in PubMed and PsycNET and obtained 14 cohort studies with unpublished individual-level data from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium. Summary estimates of the association were obtained using random-effects models. Individual-level data analyses were based on a pre-published study protocol.
ResultsWe included six published studies with a total of 27 461 individuals and 914 incident cases of clinical depression. From unpublished datasets we included 120 221 individuals and 982 first episodes of hospital-treated clinical depression. Job strain was associated with an increased risk of clinical depression in both published [relative risk (RR) = 1.77, 95% confidence interval (CI) 1.47–2.13] and unpublished datasets (RR = 1.27, 95% CI 1.04–1.55). Further individual participant analyses showed a similar association across sociodemographic subgroups and after excluding individuals with baseline somatic disease. The association was unchanged when excluding individuals with baseline depressive symptoms (RR = 1.25, 95% CI 0.94–1.65), but attenuated on adjustment for a continuous depressive symptoms score (RR = 1.03, 95% CI 0.81–1.32).
ConclusionsJob strain may precipitate clinical depression among employees. Future intervention studies should test whether job strain is a modifiable risk factor for depression.
X-ray diffraction imaging of dislocation generation related to microcracks in Si wafers
- J. Wittge, A. Danilewsky, D. Allen, P. McNally, Z. J. Li, T. Baumbach, E. Gorostegui-Colinas, J. Garagorri, M. R. Elizalde, D. Jacques, M. C. Fossati, D. K. Bowen, B. K. Tanner
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- Powder Diffraction / Volume 25 / Issue 2 / June 2010
- Published online by Cambridge University Press:
- 29 February 2012, pp. 99-103
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The nucleation of dislocations at indents in silicon following rapid thermal annealing (RTA) has been examined by X-ray diffraction imaging (topography). For indentation loads below 200 mN, no slip bands were generated from the indent sites following RTA at 1000 °C under spike conditions. Upon plateau annealing at 1000 °C, slip dislocations were propagated from some indents but not all. Slip was also observed from edge defects not associated with indentation. For 500-mN indentation load, large scale dislocation sources were generated from the indent sites propagating on two of the four {111} slip planes. These dislocations multiplied into macroscopic-scale slip bands. A significant change in morphology was observed in the 60° dislocation segments after the screw segment reached the rear surface of the wafer. Dislocations changed line direction and in some cases appeared to leave the Peierls trough during glide.
Contributors
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- By Rose Teteki Abbey, K. C. Abraham, David Tuesday Adamo, LeRoy H. Aden, Efrain Agosto, Victor Aguilan, Gillian T. W. Ahlgren, Charanjit Kaur AjitSingh, Dorothy B E A Akoto, Giuseppe Alberigo, Daniel E. Albrecht, Ruth Albrecht, Daniel O. Aleshire, Urs Altermatt, Anand Amaladass, Michael Amaladoss, James N. Amanze, Lesley G. Anderson, Thomas C. Anderson, Victor Anderson, Hope S. Antone, María Pilar Aquino, Paula Arai, Victorio Araya Guillén, S. Wesley Ariarajah, Ellen T. Armour, Brett Gregory Armstrong, Atsuhiro Asano, Naim Stifan Ateek, Mahmoud Ayoub, John Alembillah Azumah, Mercedes L. García Bachmann, Irena Backus, J. Wayne Baker, Mieke Bal, Lewis V. Baldwin, William Barbieri, António Barbosa da Silva, David Basinger, Bolaji Olukemi Bateye, Oswald Bayer, Daniel H. Bays, Rosalie Beck, Nancy Elizabeth Bedford, Guy-Thomas Bedouelle, Chorbishop Seely Beggiani, Wolfgang Behringer, Christopher M. Bellitto, Byard Bennett, Harold V. Bennett, Teresa Berger, Miguel A. Bernad, Henley Bernard, Alan E. Bernstein, Jon L. Berquist, Johannes Beutler, Ana María Bidegain, Matthew P. Binkewicz, Jennifer Bird, Joseph Blenkinsopp, Dmytro Bondarenko, Paulo Bonfatti, Riet en Pim Bons-Storm, Jessica A. Boon, Marcus J. Borg, Mark Bosco, Peter C. Bouteneff, François Bovon, William D. Bowman, Paul S. Boyer, David Brakke, Richard E. Brantley, Marcus Braybrooke, Ian Breward, Ênio José da Costa Brito, Jewel Spears Brooker, Johannes Brosseder, Nicholas Canfield Read Brown, Robert F. Brown, Pamela K. Brubaker, Walter Brueggemann, Bishop Colin O. Buchanan, Stanley M. Burgess, Amy Nelson Burnett, J. Patout Burns, David B. Burrell, David Buttrick, James P. Byrd, Lavinia Byrne, Gerado Caetano, Marcos Caldas, Alkiviadis Calivas, William J. Callahan, Salvatore Calomino, Euan K. Cameron, William S. Campbell, Marcelo Ayres Camurça, Daniel F. Caner, Paul E. Capetz, Carlos F. Cardoza-Orlandi, Patrick W. Carey, Barbara Carvill, Hal Cauthron, Subhadra Mitra Channa, Mark D. Chapman, James H. Charlesworth, Kenneth R. Chase, Chen Zemin, Luciano Chianeque, Philip Chia Phin Yin, Francisca H. Chimhanda, Daniel Chiquete, John T. Chirban, Soobin Choi, Robert Choquette, Mita Choudhury, Gerald Christianson, John Chryssavgis, Sejong Chun, Esther Chung-Kim, Charles M. A. Clark, Elizabeth A. Clark, Sathianathan Clarke, Fred Cloud, John B. Cobb, W. Owen Cole, John A Coleman, John J. Collins, Sylvia Collins-Mayo, Paul K. Conkin, Beth A. Conklin, Sean Connolly, Demetrios J. Constantelos, Michael A. Conway, Paula M. Cooey, Austin Cooper, Michael L. Cooper-White, Pamela Cooper-White, L. William Countryman, Sérgio Coutinho, Pamela Couture, Shannon Craigo-Snell, James L. Crenshaw, David Crowner, Humberto Horacio Cucchetti, Lawrence S. Cunningham, Elizabeth Mason Currier, Emmanuel Cutrone, Mary L. Daniel, David D. Daniels, Robert Darden, Rolf Darge, Isaiah Dau, Jeffry C. Davis, Jane Dawson, Valentin Dedji, John W. de Gruchy, Paul DeHart, Wendy J. Deichmann Edwards, Miguel A. De La Torre, George E. Demacopoulos, Thomas de Mayo, Leah DeVun, Beatriz de Vasconcellos Dias, Dennis C. Dickerson, John M. Dillon, Luis Miguel Donatello, Igor Dorfmann-Lazarev, Susanna Drake, Jonathan A. Draper, N. Dreher Martin, Otto Dreydoppel, Angelyn Dries, A. J. Droge, Francis X. D'Sa, Marilyn Dunn, Nicole Wilkinson Duran, Rifaat Ebied, Mark J. Edwards, William H. Edwards, Leonard H. Ehrlich, Nancy L. Eiesland, Martin Elbel, J. Harold Ellens, Stephen Ellingson, Marvin M. Ellison, Robert Ellsberg, Jean Bethke Elshtain, Eldon Jay Epp, Peter C. Erb, Tassilo Erhardt, Maria Erling, Noel Leo Erskine, Gillian R. Evans, Virginia Fabella, Michael A. Fahey, Edward Farley, Margaret A. Farley, Wendy Farley, Robert Fastiggi, Seena Fazel, Duncan S. Ferguson, Helwar Figueroa, Paul Corby Finney, Kyriaki Karidoyanes FitzGerald, Thomas E. FitzGerald, John R. Fitzmier, Marie Therese Flanagan, Sabina Flanagan, Claude Flipo, Ronald B. Flowers, Carole Fontaine, David Ford, Mary Ford, Stephanie A. Ford, Jim Forest, William Franke, Robert M. Franklin, Ruth Franzén, Edward H. Friedman, Samuel Frouisou, Lorelei F. Fuchs, Jojo M. Fung, Inger Furseth, Richard R. Gaillardetz, Brandon Gallaher, China Galland, Mark Galli, Ismael García, Tharscisse Gatwa, Jean-Marie Gaudeul, Luis María Gavilanes del Castillo, Pavel L. Gavrilyuk, Volney P. Gay, Metropolitan Athanasios Geevargis, Kondothra M. George, Mary Gerhart, Simon Gikandi, Maurice Gilbert, Michael J. Gillgannon, Verónica Giménez Beliveau, Terryl Givens, Beth Glazier-McDonald, Philip Gleason, Menghun Goh, Brian Golding, Bishop Hilario M. Gomez, Michelle A. Gonzalez, Donald K. Gorrell, Roy Gottfried, Tamara Grdzelidze, Joel B. Green, Niels Henrik Gregersen, Cristina Grenholm, Herbert Griffiths, Eric W. Gritsch, Erich S. Gruen, Christoffer H. Grundmann, Paul H. Gundani, Jon P. Gunnemann, Petre Guran, Vidar L. Haanes, Jeremiah M. Hackett, Getatchew Haile, Douglas John Hall, Nicholas Hammond, Daphne Hampson, Jehu J. Hanciles, Barry Hankins, Jennifer Haraguchi, Stanley S. Harakas, Anthony John Harding, Conrad L. Harkins, J. William Harmless, Marjory Harper, Amir Harrak, Joel F. Harrington, Mark W. Harris, Susan Ashbrook Harvey, Van A. Harvey, R. Chris Hassel, Jione Havea, Daniel Hawk, Diana L. Hayes, Leslie Hayes, Priscilla Hayner, S. Mark Heim, Simo Heininen, Richard P. Heitzenrater, Eila Helander, David Hempton, Scott H. Hendrix, Jan-Olav Henriksen, Gina Hens-Piazza, Carter Heyward, Nicholas J. Higham, David Hilliard, Norman A. Hjelm, Peter C. Hodgson, Arthur Holder, M. Jan Holton, Dwight N. Hopkins, Ronnie Po-chia Hsia, Po-Ho Huang, James Hudnut-Beumler, Jennifer S. Hughes, Leonard M. Hummel, Mary E. Hunt, Laennec Hurbon, Mark Hutchinson, Susan E. Hylen, Mary Beth Ingham, H. Larry Ingle, Dale T. Irvin, Jon Isaak, Paul John Isaak, Ada María Isasi-Díaz, Hans Raun Iversen, Margaret C. Jacob, Arthur James, Maria Jansdotter-Samuelsson, David Jasper, Werner G. Jeanrond, Renée Jeffery, David Lyle Jeffrey, Theodore W. Jennings, David H. Jensen, Robin Margaret Jensen, David Jobling, Dale A. Johnson, Elizabeth A. Johnson, Maxwell E. Johnson, Sarah Johnson, Mark D. Johnston, F. Stanley Jones, James William Jones, John R. Jones, Alissa Jones Nelson, Inge Jonsson, Jan Joosten, Elizabeth Judd, Mulambya Peggy Kabonde, Robert Kaggwa, Sylvester Kahakwa, Isaac Kalimi, Ogbu U. Kalu, Eunice Kamaara, Wayne C. Kannaday, Musimbi Kanyoro, Veli-Matti Kärkkäinen, Frank Kaufmann, Léon Nguapitshi Kayongo, Richard Kearney, Alice A. Keefe, Ralph Keen, Catherine Keller, Anthony J. Kelly, Karen Kennelly, Kathi Lynn Kern, Fergus Kerr, Edward Kessler, George Kilcourse, Heup Young Kim, Kim Sung-Hae, Kim Yong-Bock, Kim Yung Suk, Richard King, Thomas M. King, Robert M. Kingdon, Ross Kinsler, Hans G. Kippenberg, Cheryl A. Kirk-Duggan, Clifton Kirkpatrick, Leonid Kishkovsky, Nadieszda Kizenko, Jeffrey Klaiber, Hans-Josef Klauck, Sidney Knight, Samuel Kobia, Robert Kolb, Karla Ann Koll, Heikki Kotila, Donald Kraybill, Philip D. W. Krey, Yves Krumenacker, Jeffrey Kah-Jin Kuan, Simanga R. Kumalo, Peter Kuzmic, Simon Shui-Man Kwan, Kwok Pui-lan, André LaCocque, Stephen E. Lahey, John Tsz Pang Lai, Emiel Lamberts, Armando Lampe, Craig Lampe, Beverly J. Lanzetta, Eve LaPlante, Lizette Larson-Miller, Ariel Bybee Laughton, Leonard Lawlor, Bentley Layton, Robin A. Leaver, Karen Lebacqz, Archie Chi Chung Lee, Marilyn J. Legge, Hervé LeGrand, D. L. LeMahieu, Raymond Lemieux, Bill J. Leonard, Ellen M. Leonard, Outi Leppä, Jean Lesaulnier, Nantawan Boonprasat Lewis, Henrietta Leyser, Alexei Lidov, Bernard Lightman, Paul Chang-Ha Lim, Carter Lindberg, Mark R. Lindsay, James R. Linville, James C. Livingston, Ann Loades, David Loades, Jean-Claude Loba-Mkole, Lo Lung Kwong, Wati Longchar, Eleazar López, David W. Lotz, Andrew Louth, Robin W. Lovin, William Luis, Frank D. Macchia, Diarmaid N. J. MacCulloch, Kirk R. MacGregor, Marjory A. MacLean, Donald MacLeod, Tomas S. Maddela, Inge Mager, Laurenti Magesa, David G. Maillu, Fortunato Mallimaci, Philip Mamalakis, Kä Mana, Ukachukwu Chris Manus, Herbert Robinson Marbury, Reuel Norman Marigza, Jacqueline Mariña, Antti Marjanen, Luiz C. L. Marques, Madipoane Masenya (ngwan'a Mphahlele), Caleb J. D. Maskell, Steve Mason, Thomas Massaro, Fernando Matamoros Ponce, András Máté-Tóth, Odair Pedroso Mateus, Dinis Matsolo, Fumitaka Matsuoka, John D'Arcy May, Yelena Mazour-Matusevich, Theodore Mbazumutima, John S. McClure, Christian McConnell, Lee Martin McDonald, Gary B. McGee, Thomas McGowan, Alister E. McGrath, Richard J. McGregor, John A. McGuckin, Maud Burnett McInerney, Elsie Anne McKee, Mary B. McKinley, James F. McMillan, Ernan McMullin, Kathleen E. McVey, M. Douglas Meeks, Monica Jyotsna Melanchthon, Ilie Melniciuc-Puica, Everett Mendoza, Raymond A. Mentzer, William W. Menzies, Ina Merdjanova, Franziska Metzger, Constant J. Mews, Marvin Meyer, Carol Meyers, Vasile Mihoc, Gunner Bjerg Mikkelsen, Maria Inêz de Castro Millen, Clyde Lee Miller, Bonnie J. Miller-McLemore, Alexander Mirkovic, Paul Misner, Nozomu Miyahira, R. W. L. Moberly, Gerald Moede, Aloo Osotsi Mojola, Sunanda Mongia, Rebeca Montemayor, James Moore, Roger E. Moore, Craig E. Morrison O.Carm, Jeffry H. Morrison, Keith Morrison, Wilson J. Moses, Tefetso Henry Mothibe, Mokgethi Motlhabi, Fulata Moyo, Henry Mugabe, Jesse Ndwiga Kanyua Mugambi, Peggy Mulambya-Kabonde, Robert Bruce Mullin, Pamela Mullins Reaves, Saskia Murk Jansen, Heleen L. Murre-Van den Berg, Augustine Musopole, Isaac M. T. Mwase, Philomena Mwaura, Cecilia Nahnfeldt, Anne Nasimiyu Wasike, Carmiña Navia Velasco, Thulani Ndlazi, Alexander Negrov, James B. Nelson, David G. Newcombe, Carol Newsom, Helen J. Nicholson, George W. E. Nickelsburg, Tatyana Nikolskaya, Damayanthi M. A. Niles, Bertil Nilsson, Nyambura Njoroge, Fidelis Nkomazana, Mary Beth Norton, Christian Nottmeier, Sonene Nyawo, Anthère Nzabatsinda, Edward T. Oakes, Gerald O'Collins, Daniel O'Connell, David W. Odell-Scott, Mercy Amba Oduyoye, Kathleen O'Grady, Oyeronke Olajubu, Thomas O'Loughlin, Dennis T. Olson, J. Steven O'Malley, Cephas N. Omenyo, Muriel Orevillo-Montenegro, César Augusto Ornellas Ramos, Agbonkhianmeghe E. Orobator, Kenan B. Osborne, Carolyn Osiek, Javier Otaola Montagne, Douglas F. Ottati, Anna May Say Pa, Irina Paert, Jerry G. Pankhurst, Aristotle Papanikolaou, Samuele F. Pardini, Stefano Parenti, Peter Paris, Sung Bae Park, Cristián G. Parker, Raquel Pastor, Joseph Pathrapankal, Daniel Patte, W. Brown Patterson, Clive Pearson, Keith F. Pecklers, Nancy Cardoso Pereira, David Horace Perkins, Pheme Perkins, Edward N. Peters, Rebecca Todd Peters, Bishop Yeznik Petrossian, Raymond Pfister, Peter C. Phan, Isabel Apawo Phiri, William S. F. Pickering, Derrick G. Pitard, William Elvis Plata, Zlatko Plese, John Plummer, James Newton Poling, Ronald Popivchak, Andrew Porter, Ute Possekel, James M. Powell, Enos Das Pradhan, Devadasan Premnath, Jaime Adrían Prieto Valladares, Anne Primavesi, Randall Prior, María Alicia Puente Lutteroth, Eduardo Guzmão Quadros, Albert Rabil, Laurent William Ramambason, Apolonio M. Ranche, Vololona Randriamanantena Andriamitandrina, Lawrence R. Rast, Paul L. Redditt, Adele Reinhartz, Rolf Rendtorff, Pål Repstad, James N. Rhodes, John K. Riches, Joerg Rieger, Sharon H. Ringe, Sandra Rios, Tyler Roberts, David M. Robinson, James M. Robinson, Joanne Maguire Robinson, Richard A. H. Robinson, Roy R. Robson, Jack B. Rogers, Maria Roginska, Sidney Rooy, Rev. Garnett Roper, Maria José Fontelas Rosado-Nunes, Andrew C. Ross, Stefan Rossbach, François Rossier, John D. Roth, John K. Roth, Phillip Rothwell, Richard E. Rubenstein, Rosemary Radford Ruether, Markku Ruotsila, John E. Rybolt, Risto Saarinen, John Saillant, Juan Sanchez, Wagner Lopes Sanchez, Hugo N. Santos, Gerhard Sauter, Gloria L. Schaab, Sandra M. Schneiders, Quentin J. Schultze, Fernando F. Segovia, Turid Karlsen Seim, Carsten Selch Jensen, Alan P. F. Sell, Frank C. Senn, Kent Davis Sensenig, Damían Setton, Bal Krishna Sharma, Carolyn J. Sharp, Thomas Sheehan, N. Gerald Shenk, Christian Sheppard, Charles Sherlock, Tabona Shoko, Walter B. Shurden, Marguerite Shuster, B. Mark Sietsema, Batara Sihombing, Neil Silberman, Clodomiro Siller, Samuel Silva-Gotay, Heikki Silvet, John K. Simmons, Hagith Sivan, James C. Skedros, Abraham Smith, Ashley A. Smith, Ted A. Smith, Daud Soesilo, Pia Søltoft, Choan-Seng (C. S.) Song, Kathryn Spink, Bryan Spinks, Eric O. Springsted, Nicolas Standaert, Brian Stanley, Glen H. Stassen, Karel Steenbrink, Stephen J. Stein, Andrea Sterk, Gregory E. Sterling, Columba Stewart, Jacques Stewart, Robert B. Stewart, Cynthia Stokes Brown, Ken Stone, Anne Stott, Elizabeth Stuart, Monya Stubbs, Marjorie Hewitt Suchocki, David Kwang-sun Suh, Scott W. Sunquist, Keith Suter, Douglas Sweeney, Charles H. Talbert, Shawqi N. Talia, Elsa Tamez, Joseph B. Tamney, Jonathan Y. Tan, Yak-Hwee Tan, Kathryn Tanner, Feiya Tao, Elizabeth S. Tapia, Aquiline Tarimo, Claire Taylor, Mark Lewis Taylor, Bishop Abba Samuel Wolde Tekestebirhan, Eugene TeSelle, M. Thomas Thangaraj, David R. Thomas, Andrew Thornley, Scott Thumma, Marcelo Timotheo da Costa, George E. “Tink” Tinker, Ola Tjørhom, Karen Jo Torjesen, Iain R. Torrance, Fernando Torres-Londoño, Archbishop Demetrios [Trakatellis], Marit Trelstad, Christine Trevett, Phyllis Trible, Johannes Tromp, Paul Turner, Robert G. Tuttle, Archbishop Desmond Tutu, Peter Tyler, Anders Tyrberg, Justin Ukpong, Javier Ulloa, Camillus Umoh, Kristi Upson-Saia, Martina Urban, Monica Uribe, Elochukwu Eugene Uzukwu, Richard Vaggione, Gabriel Vahanian, Paul Valliere, T. J. Van Bavel, Steven Vanderputten, Peter Van der Veer, Huub Van de Sandt, Louis Van Tongeren, Luke A. Veronis, Noel Villalba, Ramón Vinke, Tim Vivian, David Voas, Elena Volkova, Katharina von Kellenbach, Elina Vuola, Timothy Wadkins, Elaine M. Wainwright, Randi Jones Walker, Dewey D. Wallace, Jerry Walls, Michael J. Walsh, Philip Walters, Janet Walton, Jonathan L. Walton, Wang Xiaochao, Patricia A. Ward, David Harrington Watt, Herold D. Weiss, Laurence L. Welborn, Sharon D. Welch, Timothy Wengert, Traci C. West, Merold Westphal, David Wetherell, Barbara Wheeler, Carolinne White, Jean-Paul Wiest, Frans Wijsen, Terry L. Wilder, Felix Wilfred, Rebecca Wilkin, Daniel H. Williams, D. Newell Williams, Michael A. Williams, Vincent L. Wimbush, Gabriele Winkler, Anders Winroth, Lauri Emílio Wirth, James A. Wiseman, Ebba Witt-Brattström, Teofil Wojciechowski, John Wolffe, Kenman L. Wong, Wong Wai Ching, Linda Woodhead, Wendy M. Wright, Rose Wu, Keith E. Yandell, Gale A. Yee, Viktor Yelensky, Yeo Khiok-Khng, Gustav K. K. Yeung, Angela Yiu, Amos Yong, Yong Ting Jin, You Bin, Youhanna Nessim Youssef, Eliana Yunes, Robert Michael Zaller, Valarie H. Ziegler, Barbara Brown Zikmund, Joyce Ann Zimmerman, Aurora Zlotnik, Zhuo Xinping
- Edited by Daniel Patte, Vanderbilt University, Tennessee
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- The Cambridge Dictionary of Christianity
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- 05 August 2012
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- 20 September 2010, pp xi-xliv
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Sporadic Cryptosporidium infection in Nigerian children: risk factors with species identification
- S. F. MOLLOY, C. J. TANNER, P. KIRWAN, S. O. ASAOLU, H. V. SMITH, R. A. B. NICHOLS, L. CONNELLY, C. V. HOLLAND
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- Journal:
- Epidemiology & Infection / Volume 139 / Issue 6 / June 2011
- Published online by Cambridge University Press:
- 27 August 2010, pp. 946-954
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A cross-sectional study was conducted to investigate risk factors for sporadic Cryptosporidium infection in a paediatric population in Nigeria. Of 692 children, 134 (19·4%) were infected with Cryptosporidium oocysts. Cryptosporidium spp. were identified in 49 positive samples using PCR–restriction fragment length polymorphism and direct sequencing of the glycoprotein60 (GP60) gene. Generalized linear mixed-effects models were used to identify risk factors for all Cryptosporidium infections, as well as for C. hominis and C. parvum both together and separately. Risk factors identified for all Cryptosporidium infections included malaria infection and a lack of Ascaris infection. For C. hominis infections, stunting and younger age were highlighted as risk factors, while stunting and malaria infection were identified as risk factors for C. parvum infection.
Campylobacter enteritis in general practice
- E. J. C. Kendall, Elizabeth I. Tanner
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- Journal of Hygiene / Volume 88 / Issue 2 / April 1982
- Published online by Cambridge University Press:
- 25 March 2010, pp. 155-163
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The incidence and clinical features of campylobacter enteritis were studied in a defined general practice population over a period of three years. Specimens of faeces were cultured from a representative sample of patients suffering from acute enteritis. Of 168 patients submitting a specimen to the laboratory 34 (20·2%) were positive for thermophilic Campylobacter species. The projected campylobacter infection rate varied from 5·4% per annum in infancy to 0·3% per annum in the 5- to 14-year-olds with a mean of 1·1% per annum for the whole study population.
During the same period campylobacters were isolated from 484 (14·9%) of 3250 patients suffering from acute enteritis whose general practitioners had sent faecal specimens to the laboratory, confirming the importance of this organism in the aetiology of acute enteritis in the community.
Changes in light below the canopy of a Jamaican montane rainforest after a hurricane
- P. J. Bellingham, E. V. J. Tanner, P. M. Rich, T. C. R. Goodland
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- Journal of Tropical Ecology / Volume 12 / Issue 5 / September 1996
- Published online by Cambridge University Press:
- 10 July 2009, pp. 699-722
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Hurricane Gilbert caused disturbance to Jamaican montane rainforests in 1988. This study provides a detailed characterization of landscape-level changes in light below the canopy of these forests after the hurricane. Hemispherical photographs were taken below the forest canopy at four sites at permanent points 1 m above the ground between 7 and 33 mo after the hurricane. For each photograph photosynthetically active radiation (PAR) was computed. PAR declined exponentially in all sites during the period of measurement. During the first 24 mo after the hurricane, PAR beneath the canopy was significantly greater in sites that had been defoliated during the hurricane than in sites where few trees had been defoliated. By 28 mo after the hurricane there was no significant difference in PAR beneath the canopy among the four sites. By 33 mo after the hurricane canopy recovery was nearly complete and PAR was only slightly higher than measurements made before the hurricane. Our results were compared with studies of changes in light environment resulting from treefall gaps and under deciduous canopies. PAR during the first 18 mo after the hurricane was similar to that recorded in small canopy gaps in other forests. Widespread defoliation caused by hurricanes can thus increase PAR beneath the canopy over large areas and consequently opportunities may arise for widespread recruitment of tree species in response to increased light levels.
Aggregation in schistosomiasis: comparison of the relationships between prevalence and intensity in different endemic areas
- H. L. Guyatt, T. Smith, B. Gryseels, C. Lengeler, H. Mshinda, S. Siziya, B. Salanave, N. Mohome, J. Makwala, K. P. Ngimbi, M. Tanner
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- Parasitology / Volume 109 / Issue 1 / July 1994
- Published online by Cambridge University Press:
- 06 April 2009, pp. 45-55
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Distributions of the intensities of helminth infections within their host populations are invariably aggregated. In the case of the intestinal nematodes, the degrees of aggregation have been shown to be species specific, and constant for any given species despite geographical variation in study sites. This species-specific aggregation can be quantified and used as a tool in planning control interventions. One practical application is that the prevalence of infection can be used to predict the prevalence of heavy infection and thus the risks of morbidity. This paper investigates the patterns of aggregation in schistosome egg counts in different endemic areas in Africa (data sets were obtained from Burundi, Cameroon, Tanzania, Zambia and Zaire). The analysis demonstrates that the degree of parasite aggregation, for both Schistosoma mansoni and S. haematobium, differs amongst the different study localities. This is probably due to area-specific differences in host exposure and immunity. This implies that for these schistosome species, it is not possible to predict egg count distributions or morbidity levels from prevalence data alone.
Astrometric planet searches with SIM PlanetQuest
- C. A. Beichman, S. C. Unwin, M. Shao, A. M. Tanner, J. H. Catanzarite, G. W. Marcy
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- Journal:
- Proceedings of the International Astronomical Union / Volume 3 / Issue S248 / October 2007
- Published online by Cambridge University Press:
- 01 October 2007, pp. 238-243
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- October 2007
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SIM will search for planets with masses as small as the Earth's orbiting in the ‘habitable zones’ around more than 100 of the nearest stars and could discover many dozen if Earth-like planets are common. With a planned “Deep Survey” of 100–450 stars (depending on desired mass sensitivity) SIM will search for terrestrial planets around all of the candidate target stars for future direct detection missions such as Terrestrial Planet Finder and Darwin. SIM's “Broad Survey” of 2100 stars will characterize single and multiple-planet systems around a wide variety of stellar types, including many now inaccessible with the radial velocity technique. In particular, SIM will search for planets around young stars providing insights into how planetary systems are born and evolve with time.
Growth of Large Diameter Semi-Insulating 6H-SiC Crystals by Physical Vapor Transport
- M. Yoganathan, A. Gupta, E. Semenas, E. Emorhokpor, C. Martin, T. Kerr, I Zwieback, A. E. Souzis, T.A. Anderson, C.D. Tanner, J. Chen, D.L. Barrett, R.H. Hopkins, C.J. Johnson, Fei Yan, W.J. Choyke, R.P. Devaty
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- Journal:
- MRS Online Proceedings Library Archive / Volume 815 / 2004
- Published online by Cambridge University Press:
- 15 March 2011, J5.9
- Print publication:
- 2004
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Semi-insulating (SI) 6H-SiC boules up to 110mm in diameter have been grown by Physical Vapor Transport (PVT). SI properties have been achieved by vanadiumc compensation, which resulted in the room temperature electrical resistivity exceeding 2×1011ωcm. Low temperature photoluminescence (LTPL) data shows the presence of the deep intrinsic defect level UD-1 in addition to V4+. The nitrogen-bound exciton (NBE) luminescence is weak in heavily vanadium compensated 6H-SiC.
6H and 4H-SiC Bulk Growth by PVT and Advanced PVT (APVT)
- A. Gupta, M. Yoganathan, E. Semenas, I. Zwieback, E. Emorhokpor, C. Martin, T. Kerr, A. Souzis, T. Anderson, J. Chen, C. Tanner, D. Barrett, R. Hopkins, C. Johnson
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- Journal:
- MRS Online Proceedings Library Archive / Volume 815 / 2004
- Published online by Cambridge University Press:
- 15 March 2011, J5.24
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- 2004
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II-VI, Inc. is a commercial supplier of high-quality SiC substrates (including 2-inch and 3-inch diameter) for RF and power applications to the US market. Semi-insulating 6H-SiC single crystals, doped with vanadium and undoped (vanadium-free), as well as ntype 4H crystals have been grown using the PVT and Advanced PVT (APVT) growth techniques. The APVT process incorporates insitu synthesis and growth of of SiC crystal from Si and C precursors.
Grown 6H-SiC and 4H-SiC crystals have been extensively characterized with respect to their purity, crystal quality and electrical properties. COREMA resistivity maps demonstrate that V-compensated boules exhibited axially and radially uniform resistivity around 1011 ω.cm at room temperature. Undoped (V-free) wafers contained residual boron and nitrogen at levels below 1016 atoms/cm3, and demonstrated semi-insulating properties (resistivity between 106 and 1011 ω.cm) as a result of compensation by native point defects with deep levels in the bandgap. The undoped semi-insulating crystals grown by APVT contained boron and nitrogen at 1.9ω1015 cm−3 and 3.8.1015 cm−3, respectively.
High-quality 2-inch SiC wafers exhibited micropipe densities on the order of 10 cm−2 and dislocation density on the order of 104 cm−2.
Relative contribution of day-to-day and intra-specimen variation in faecal egg counts of Schistosoma mansoni before and after treatment with praziquantel
- J. UTZINGER, M. BOOTH, E. K. N'GORAN, I. MÜLLER, M. TANNER, C. LENGELER
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- Journal:
- Parasitology / Volume 122 / Issue 5 / May 2001
- Published online by Cambridge University Press:
- 07 August 2001, pp. 537-544
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There is evidence that faecal egg counts of Schistosoma mansoni vary considerably from day to day, which results in poor sensitivity of single stool readings. Intra-specimen variation of S. mansoni egg counts may also be considerable, but has previously been considered as the less important component. We quantified the relative contribution of these two sources of variation among 96 schoolchildren from an area in Côte d'Ivoire highly endemic for S. mansoni. Stool specimens were collected over 5 consecutive days, and 5 egg-counts were made in each specimen by the Kato–Katz technique. The point prevalence of the first sample was 42.7% and the cumulative prevalence after the maximum sampling effort was 88.5%. Using generalized linear mixed models we found that the presence of S. mansoni eggs in a stool sample varied much more between days than within specimens, indicating that stool sample examination over multiple days is required for accurate prevalence estimates. However, using the same approach, we found that among infected children intra-specimen variation in egg counts was 4.3 times higher than day-to-day variation. After praziquantel administration, day-to-day variation was more important than before, since most infections were very light and thus likely to be missed altogether by stool examination on a single day. We conclude that diagnostic sensitivity in high transmission areas is maximized by making several stool readings on several days, but examining 1 stool specimen several times can make reasonable estimates of infection intensity.
Edge effects on litterfall mass and nutrient concentrations in forest fragments in central Amazonia
- NIGEL C. SIZER, EDMUND V. J. TANNER, ISOLDE D. KOSSMANN FERRAZ
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- Journal:
- Journal of Tropical Ecology / Volume 16 / Issue 6 / November 2000
- Published online by Cambridge University Press:
- 17 January 2001, pp. 853-863
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Forest edges bordering on pasture were created by cutting and burning the surrounding Amazonian lowland rain forest in the dry season (June) of 1990. Litterfall was measured for 3.5 y along transects 10, 50, 100 and 250-m into the forest from the forest edge. Litterfall along the 10-m transects increased by up to 2.5 times that on spatial controls (250-m transects) in the dry season in which the edge was created. In the second dry season after edge creation litterfall at 10-m was lower than on controls, after which it returned to control rates in the second wet season, 1.5 y after edge creation. Litterfall 50-m into the forest was less affected; there was a smaller rise in the dry season in which the edge was cut, and no significant effects after that. At 100-m there was no effect of edge creation on litterfall. Phosphorus concentrations in litterfall were elevated along 10-m transects, 10–12 wk after edge creation, possibly because of reduced retranslocation prior to abscission. The changes in litterfall described here are inextricably linked to the biomass collapse, which occurs near forest-fragment edges in the same area.