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2. Review of the thermo-tectonic evolution of the Central Zone of the Limpopo Complex with implications for conflicting published geodynamic models.

Author

van Reenen, D. D., Clark, M. D., Smit, C. A., Tsunogae, T., and Safonov, O.

Subjects
SHEAR zones, NEOARCHAEAN
Abstract

This paper addresses the credibility of published data utilised to underpin conflicting models recently proposed for the geodynamic evolution of the Limpopo Complex (LC), Southern Africa, in the Neoarchaean and Palaeoproterozoic. We are mainly focused on the tectonic and metamorphic processes that affected the Central Zone (CZ) of the LC, but also consider the significance of the timing of the thermo-tectonic interaction of the Southern Marginal Zone (SMZ) of the LC with the granite-greenstone terrane of the Kaapvaal Craton (KVC) at the position of the steep north-dipping Hout River Shear Zone (HRSZ). HRSZ-linked tectonism at the contact with the KVC is expressed as a narrow "hot-iron zone" directly dated at 2.72 to 2.69 Ga and developed in the footwall of the north-dipping HRSZ. HRSZ-linked tectonic activity intermittently continued up to 2.65 to 2.62 Ga with no structural-metamorphic or geochronological evidence that the SMZ and the rest of the KVC were affected by regional thermo-tectonic (orogenic) activity after ca. 2.68 Ga. The complementary This paper addresses the credibility of published data utilised to underpin conflicting models recently proposed for the geodynamic evolution of the Limpopo Complex (LC), Southern Africa, in the Neoarchaean and Palaeoproterozoic. We are mainly focused on the tectonic and metamorphic processes that affected the Central Zone (CZ) of the LC, but also consider the significance of the timing of the thermo-tectonic interaction of the Southern Marginal Zone (SMZ) of the LC with the granite-greenstone terrane of the Kaapvaal Craton (KVC) at the position of the steep north-dipping Hout River Shear Zone (HRSZ). HRSZ-linked tectonism at the contact with the KVC is expressed as a narrow "hot-iron zone" directly dated at 2.72 to 2.69 Ga and developed in the footwall of the north-dipping HRSZ. HRSZ-linked tectonic activity intermittently continued up to 2.65 to 2.62 Ga with no structural-metamorphic or geochronological evidence that the SMZ and the rest of the KVC were affected by regional thermo-tectonic (orogenic) activity after ca. 2.68 Ga. The complementary [ABSTRACT FROM AUTHOR]

Published
2023
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5. Identification of Nucleate Boiling as the Dominant Heat Transfer Mechanism during Confined Two-Phase Jet Impingement

Author

Clark, M. D., Weibel, J. A., and Garimella, S V

Subjects
Physics::Fluid Dynamics, Two-phase heat transfer, Electronics cooling, Pool boiling, Astrophysics::High Energy Astrophysical Phenomena, Critical heat flux, Jet impingement
Abstract

Thermal management of high-power electronics requires cooling strategies capable of dissipating high heat fluxes while maintaining the device at low operating temperatures. Two-phase jet impingement offers a compact cooling technology capable of meeting these requirements at a low pressure drop. Generally, confined impingement geometries are used in electronics cooling applications, where the flow is constrained between the hot surface and orifice plate. Understanding the primary heat transfer mechanisms occurring as boiling takes place on the surface during jet impingement is important, specifically under such confined conditions. In this study, heat transfer from a copper surface is experimentally characterized in both confined jet impingement and pool boiling configurations. The dielectric liquid HFE- 7100 is used as the working fluid. For the jet impingement configuration, the jet issues through a single 2 mm-diameter orifice, at jet exit velocities of 1, 3, 6, and 9 m/s, into a confinement gap with a spacing of 3 jet diameters between the orifice and heat source. Additional orifice-to-target spacings of 0.5, 1, and 10 jet diameters are tested at the lowest (Vj = 1 m/s) and highest (Vj = 9 m/s) jet velocities. By incrementing the heat flux applied to the surface and observing the steady-state response at each flux, the single-phase and two-phase heat transfer performance is characterized; all experiments were carried through to critical heat flux conditions. The jet impingement data in the fully boiling regime either directly overlap the pool boiling data, or coincide with an extension of the trend in pool boiling data beyond the pool boiling critical heat flux limit. This result confirms that nucleate boiling is the dominant heat transfer mechanism in the fully boiling regime in confined jet impingement; the convective effects of the jet play a negligible role over the wide range of parameters considered here. While the presence of the jet does not enhance the boiling heat transfer coefficient, the jet does greatly increase single-phase heat transfer performance and extends the critical heat flux limit. Critical heat flux displays a linear dependence on jet velocity while remaining insensitive to changes in the orifice-to-target spacing.

Published
2019

6. Cervical cancer screening decentralized policy adaptation: an African rural-context-specific systematic literature review

Author

Rahman, R., primary, Clark, M. D., additional, Collins, Z., additional, Traore, F., additional, Dioukhane, E. M., additional, Thiam, H., additional, Ndiaye, Y., additional, De Jesus, E. L., additional, Danfakha, N., additional, Peters, K. E., additional, Komarek, T., additional, Linn, A. M., additional, Linn, P. E., additional, Wallner, K. E., additional, Charles, M., additional, Hasnain, M., additional, Peterson, C. E., additional, and Dykens, J. A., additional

Published
2019
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8. Evolutionary genomics of the cold-Adapted diatom Fragilariopsis cylindrus

Author

Mock, T., Otillar, R. P., Strauss, Jan, McMullan, M., Paajanen, P., Schmutz, J., Salamov, A., Sanges, R., Toseland, A., Ward, B. J., Allen, A. E., Dupont, C. L., Frickenhaus, S., Maumus, F., Veluchamy, A., Wu, T., Barry, K. W., Falciatore, A., Ferrante, M. I., Fortunato, A. E., Glöckner, G., Gruber, A., Hipkin, R., Janech, M. G., Kroth, P. G., Leese, F., Lindquist, E. A., Lyon, B. R., Martin, J., Mayer, C., Parker, M., Quesneville, H., Raymond, J. A., Uhlig, C., Valas, R. E., Valentin, K. U., Worden, Alexandra Z., Armbrust, E. V., Clark, M. D., Bowler, C., Green, B. R., Moulton, V., Van Oosterhout, C., Grigoriev, I. V., Mock, T., Otillar, R. P., Strauss, Jan, McMullan, M., Paajanen, P., Schmutz, J., Salamov, A., Sanges, R., Toseland, A., Ward, B. J., Allen, A. E., Dupont, C. L., Frickenhaus, S., Maumus, F., Veluchamy, A., Wu, T., Barry, K. W., Falciatore, A., Ferrante, M. I., Fortunato, A. E., Glöckner, G., Gruber, A., Hipkin, R., Janech, M. G., Kroth, P. G., Leese, F., Lindquist, E. A., Lyon, B. R., Martin, J., Mayer, C., Parker, M., Quesneville, H., Raymond, J. A., Uhlig, C., Valas, R. E., Valentin, K. U., Worden, Alexandra Z., Armbrust, E. V., Clark, M. D., Bowler, C., Green, B. R., Moulton, V., Van Oosterhout, C., and Grigoriev, I. V.

Abstract

The Southern Ocean houses a diverse and productive community of organisms. Unicellular eukaryotic diatoms are the main primary producers in this environment, where photosynthesis is limited by low concentrations of dissolved iron and large seasonal fluctuations in light, temperature and the extent of sea ice. How diatoms have adapted to this extreme environment is largely unknown. Here we present insights into the genome evolution of a cold-Adapted diatom from the Southern Ocean, Fragilariopsis cylindrus, based on a comparison with temperate diatoms. We find that approximately 24.7 per cent of the diploid F. cylindrus genome consists of genetic loci with alleles that are highly divergent (15.1 megabases of the total genome size of 61.1 megabases). These divergent alleles were differentially expressed across environmental conditions, including darkness, low iron, freezing, elevated temperature and increased CO 2 . Alleles with the largest ratio of non-synonymous to synonymous nucleotide substitutions also show the most pronounced condition-dependent expression, suggesting a correlation between diversifying selection and allelic differentiation. Divergent alleles may be involved in adaptation to environmental fluctuations in the Southern Ocean. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

Published
2017
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10. Quantitative trait loci identified for foliar phylloxera resistance in a hybrid grape population.

Author

Clark, M. D., Teh, S. L., Burkness, E., Moreira, L., Watson, G., Yin, L., Hutchison, W. D., and Luby, J. J.

Subjects
*PHYLLOXERA, *HYBRID fruit, *GRAPES, *FRUIT, *PLANT breeding, *GREENHOUSES
Abstract

Abstract: Background and Aims: A hybrid grapevine biparental mapping population was evaluated for resistance to grape phylloxera (Daktulosphaira vitifoliae Fitch) in the greenhouse and in the field. The family (n = 125) was derived from a cross of two University of Minnesota breeding selections from a complex pedigree with multiple Vitis species. Methods and Results: The vines were evaluated for foliar phylloxera severity using visual rating in the field for multiple years. In the greenhouse, a replicated experimental design was used to quantify phylloxera severity using different traits including number of galls per plant, area under the disease progress curve, proportion of leaves with galls, average number of galls per leaf and visual rating. The plants used in the greenhouse experiment were also visually rated for root infestation. Conclusions: Quantitative trait loci (QTL) mapping for the foliar resistance traits (reduced severity) routinely identified the region spanning ~10 to 30 cM on linkage group (LG) 14 to be associated with resistance, and inherited from the mother parent MN1264. The plants used in the greenhouse experiment were also visually rated for root infestation, and subsequent QTL mapping identified regions on LG 5 of the maternal map and LG 10 of the paternal map (MN1246) associated with root resistance. Significance of the Study: The new QTLs identified in this report are potential novel sources of resistance and the first report of QTL for foliar phylloxera resistance in a hybrid grapegrowing region of North America. Molecular markers linked to resistance can be utilised in marker‐assisted breeding. [ABSTRACT FROM AUTHOR]

Published
2018
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11. Prioritizing patients for renal transplantation?: Analysis of patient preferences for kidney allocation according to ethnicity and gender

Author

Clark, M D, Gumber, Anil, Leech, D, Moro, D, Szczepura, A K, West, N, and Higgins, R M

Abstract

Revisions to UK transplant allocation policy in 2006 marked a policy shift towards ascribing higher priority to people who had been waiting for a long time for transplants, and to young adults, at the expense of emphasising tissue match between donor and recipient. This benefited members of ethnic minorities because of a shortage of donors from some ethnic groups. However, the change was informed by dated research which was not specific to the UK, and which failed to address ethnic or gender-related differences in preferences. Preference information was elicited using discrete choice experiment (DCE) questionnaires (in English, Punjabi, Hindi, Bengali, Gujarati and Urdu) from 908 patients (508 males and 397 females). Of the 908 repondents, 96 were members of ethnicminority groups, namely white ethnic minorities (27/908) and non-white ethnic minorities (69/908), including 50 South Asians. Priority criteria included length of time spent waiting for a transplant, quality of the donor-recipient tissue match, number of adult and/or child dependants of the recipient, and whether the recipient had diseases that affected their life expectancy or quality of life. Econometric results provided evidence that preferences differed slightly according to gender, but differed to a greater extent according to ethnic origin. In significant contrast to other patients, members of non-white and South Asian ethnic minorities did not tend to prioritise recipients with a good tissue match, nor, unlike patients more generally, did they tend to prioritise younger recipients. Non-white and South Asian ethnic minorities were also less likely to prioritise those with moderate rather than severe diseases affecting life expectancy. These results reinforce the case for recognising differences in ethnic-minority group preferences in transplant allocation policy.

Published
2009

13. Turning the pages : adolescents, schools and reading

Author

Clark, M. D. (Margaret Dianne), 1943 and Clark, M. D. (Margaret Dianne), 1943

Abstract

This study focuses on adolescents and reading. My premise is that adolescents develop a reading identity which is influenced by an existent reading culture to which they are exposed. This existent reading culture can be influenced in particular by schooling, family and the opinions of peers. One major influence is the classroom. Within the English curriculum, what criteria do English teachers use for selection of set texts and are there differences in criteria in all-boy/all girl and co-educational schools? I reflected on the prevailing perceptions that relate to gender, masculinity and popular culture which can affect what it means to be a boy, literate, and a reader of fictional texts. My first folio piece examines adolescents’ reading within five secondary schools, including an all-boy school, to ascertain whether boys in single-sex schools read more fictional texts and whether they enjoy reading more than their counterparts in co-educational schools. Authors are frequently invited to visit schools and work with students. My second folio piece investigates author visits in five secondary schools, from the perspectives of English teachers, teacher librarians and cohorts of middle school students. I wanted to find out why schools ask authors to visit and what are the expected outcomes of these visits, particularly in regard to adolescent reading identities. The third folio piece examines authors’ narratives concerning school visits. Authors have certain expectations when working with students and talking about their writing. I wanted to discover how authors think they can provide maximum impact on students through their visits, by asking a cohort of authors to recount their ‘dream school’ visits and ‘nightmare school’ visits. Interpretations of the research about boys and reading, and author visits from the schools’ perspectives are analysed using a form of content analysis. The third research project concerning authors’ narratives is interpreted using lexical netw

Published
2003

16. The Last Word

Author

Rosenthal, D., primary, Matsuura, J. H., additional, and Clark, M. D., additional

Published
2000
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24. Low-voltage tunnel-injection electroluminescent devices.

Author

Clark, M. D., Baidyaroy, S., Ryan, F., and Ballantyne, J. M.

Abstract

Tunnel-injection electroluminescence has been observed in Al-Al2O3-GaAs and Pt-Al203-CdS devices formed by vacuum deposition of thin films onto n-type semiconductor crystals. Results show a luminescence voltage threshold comparable to the semiconductor bandgap, and high hole injection efficiency. [ABSTRACT FROM PUBLISHER]

Published
1974
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26. EVALUATING THE EMPLACEMENT MECHANISMS OF VREDEFORT IMPACT MELT DIKES.

Author

Huber, M. S., Kovaleva, E., Clark, M. D., and Fourie, F.

Subjects
DIKES (Geology), MELTING, CRYSTALLINE rocks, X-ray fluorescence
Abstract

Methods: Four granophyre dikes, namely the Kopjeskraal, Daskop, Lesutoskraal, and Holfontein dikes, were investigated by electrical resistivity tomography (ERT), a nondestructive geophysical method described in [8]. The KGB has greater CaO, FeO, and MgO than the KGA or core dikes, but less SiO 2 or K 2 O. Discussion: The highly resistive material that corresponds to granophyre dikes does not extend deep into the subsurface. Unlike the core dikes, the Kopjeskraal granophyre dike is composed of two distinct textural and geochemical phases, the Kopjeskraal granophyre A (KGA) and Kopjeskraal granophyre B (KGB). [Extracted from the article]

Published
2020

29. An oligonucleotide fingerprint normalized and expressed sequence tag characterized zebrafish cDNA library.

Author

Clark, M D, Hennig, S, Herwig, R, Clifton, S W, Marra, M A, Lehrach, H, Johnson, S L, and tW, Group

Abstract

The zebrafish is a powerful system for understanding the vertebrate genome, allowing the combination of genetic, molecular, and embryological analysis. Expressed sequence tags (ESTs) provide a rapid means of identifying an organism's genes for further analysis, but any EST project is limited by the availability of suitable libraries. Such cDNA libraries must be of high quality and provide a high rate of gene discovery. However, commonly used normalization and subtraction procedures tend to select for shorter, truncated, and internally primed inserts, seriously affecting library quality. An alternative procedure is to use oligonucleotide fingerprinting (OFP) to precluster clones before EST sequencing, thereby reducing the re-sequencing of common transcripts. Here, we describe the use of OFP to normalize and subtract 75,000 clones from two cDNA libraries, to a minimal set of 25,102 clones. We generated 25,788 ESTs (11,380 3' and 14,408 5') from over 16,000 of these clones. Clustering of 10,654 high-quality 3' ESTs from this set identified 7232 clusters (likely genes), corresponding to a 68% gene diversity rate, comparable to what has been reported for the best normalized human cDNA libraries, and indicating that the complete set of 25,102 clones contains as many as 17,000 genes. Yet, the library quality remains high. The complete set of 25,102 clones is available for researchers as glycerol stocks, filters sets, and as individual EST clones. These resources have been used for radiation hybrid, genetic, and physical mapping of the zebrafish genome, as well as positional cloning and candidate gene identification, molecular marker, and microarray development.

Published
2001
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31. Estimating Net Nitrogen Mineralization from Carbon Dioxide Evolution

Author

Gilmour, J. T., Clark, M. D., and Sigua, G. C.

Abstract

The ability to estimate net N mineralization from C decomposition data has the potential to improve our understanding of N dynamics in soil systems. It was the objective of this study to study this relationship using substrates with varying decomposition rates and C/N ratios. Five substrates including sewage sludge, alfalfa (Medicago sativaL.), clover (Trifoliumsp.), bermudagrass [Cynodon dactylon(L.) Pers.] and ryegrass (Lolium multiflorumLam.) were incubated in Crowley silt loam (Typic Albaqualfs) or Captina silt loam (Typic Fragiudults) soil at known soil temperatures and moistures. Concurrent CO2evolution and soil inorganic N concentrations were measured periodically. A significant linear relationship between N mineralization and CO2evolution was found experimentally for each substrate. A computer simulation model was developed which used first order kinetics for conversion of substrate C to CO2. Substrate C mineralization rate constants, substrate C/N ratios and microbial efficiency were primary inputs, while substrate, biomass, and soil organic matter were the major compartments of the model. Microbial efficiency was defined for any C pool undergoing decomposition as the ratio of assimilated C to assimilated C plus dissimilated C. An important feature of the approach was the introduction of a fraction with a C/N ratio of protein that decomposed very rapidly for those substrates where initial N mineralization was large while CO2evolution was small. Model predictions of both CO2evolution and net N mineralization were in good agreement with experimental results.

Published
1985
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34. Case report 589: Use of Ostamer in fusion of lumbar spine, postoperative appearance.

Author

Gonda, R L Jr, Osher, D L, Poretta, C, and Clark, M D

Abstract

In the late 1950s and early 1960s there was intense orthopedic interest in a plastic polyurethane foam (Ostamer) that could be used in the fixation of fractures, performance of arthrodesis, and in spinal fusions. It saw limited success at that time but eventually fell from favor. A patient presenting with a draining sinus in the buttock, back pain, and a history of lumbar spinal fusion with Ostamer was recently scanned in our department. The CT appearance of Ostamer and a brief review of the literature are reported. [ABSTRACT FROM AUTHOR]

Published
1990

36. GaAs Surface Passivation for Device Applications.

Author

HUGHES RESEARCH LABS MALIBU CA, Anderson,C L, Clark,M D, HUGHES RESEARCH LABS MALIBU CA, Anderson,C L, and Clark,M D

Abstract

This report describes the progress in the second six-month period of a program to develop deposited dielectrics for GaAs device applications. Three applications of the dielectrics are being investigated: (1) isolation of control electrodes, (2) passivation of the GaAs surface, and (3) encapsulation of completed circuits. The dielectrics being studied include silicon oxynitride; mixtures of silicon nitride and germanium nitride; and mixtures of silicon dioxide, gallium oxide, and aluminum oxide. During this reporting period, studies of the interface properties of pyrolytically deposited Si3N4 on n-type GaAs under illuminated conditions were performed. The data obtained are consistent with the interpretation that inversion of the GaAs surface is being achieved. In addition, process parameters for plasma-enhanced deposition of silicon nitride films with low oxygen content and refractive index near that of stoichiometric Si3N4 were determined. Evaluation of the interface properties of SiO2 films deposited on GaAs by photochemical deposition is also reported. (Author), See also Rept. nos. AFAL-TR-79-1057, AD-A075 479 and AFAL-TR-79-1234, AD-A084 210.

Published
1980

37. GaAs Surface Passivation for Device Applications.

Author

HUGHES RESEARCH LABS MALIBU CA, Anderson ,C L, Clark ,M D, Peters,J W, HUGHES RESEARCH LABS MALIBU CA, Anderson ,C L, Clark ,M D, and Peters,J W

Abstract

This report describes the initial stages of a program to develop deposited dielectrics for GaAs device applications. Three applications of the dielectrics are being investigated: (1) isolation of control electrodes, (2) passivation of the GaAs surface, and (3) encapsulation of completed circuits. The dielectrics being studied include silicon oxynitride; mixtures of silicon nitrode and germanium nitride; and mixtures of silicon dioxide, gallium oxide, and aluminum oxide. Deposition techniques being employed are pyrolytic chemical vapor deposition, plasma-enhanced deposition, and photochemical deposition. This report describes the apparatus being used for this program and the chemical analysis of preliminary films deposited. No interface state measurements are reported. (Author)

Published
1979

38. GaAs Surface Passivation for Device Applications.

Author

HUGHES RESEARCH LABS MALIBU CA, Anderson,C L, Clark,M D, HUGHES RESEARCH LABS MALIBU CA, Anderson,C L, and Clark,M D

Abstract

This report describes the progress in the fifth six-month period of a program to develop deposited dielectrics for GaAs device applications. Three applications of the dielectrics have been investigated on this program: (1) isolation of control electrodes, (2) passivation of the GaAs surface, and (3) encapsulation of completed circuits. The dielectrics studied have included silicon oxynitride and mixtures of silicon nitride with germanium nitride. During this reporting period the activities performed emphasized a parametric study of plasma-enhanced deposition (PED) of silicon nitride. The overall process involves cleaning of the sample, anodic oxidation of the GaAs surface, stripping of the anodic oxide, an optional final wet-chemical surface preparation step, pre-deposition plasma-enhanced treatment of the walls of the deposition system or 'preburn' (which may involve a concurrent sample surface treatment), optional plasma etching of the sample surface, and deposition of the dielectric. We have analyzed the effects of variations in (1) oxide stripping and final wet-chemical preparation procedures, (2) preburn, (3) plasma etches, and (4) deposition procedures on the electrical properties of the GaAs/silicon nitride interface. None of the procedures investigated yielded interfaces useful for fabrication of practical GaAs insulated-gate transistors or integrated circuits. In addition, we have performed preliminary studies to determine appropriate parameters for the plasma-enhanced deposition of germanium nitride and mixtures of silicon nitride with germanium nitride. (Author)

Published
1982

40. Eliciting preferences using discrete choice experiments in healthcare : willingness to pay, stakeholder preferences, and altruistic preferences

Author

Clark, M. D. (Michael D.)

Subjects
HF, RA
Abstract

Chapter 1 of the thesis is divided into 5 sections. Section A begins by defining a Discrete Choice Experiment (DCE), and outlines the key stages involved in conducting a DCE. Sections B and C outline theories underpinning DCE analysis. Section B outlines the characteristics theory of demand, whilst section C, explains random utility theory (RUT), compensating variation (CV), marginal willingness to pay (MWTP), and willingness to pay (WTP) analysis. Section D of the thesis provides a review of the DCE literature. Section E outlines the research questions addressed in the thesis including calculating WTP and hypothetical bias; the description of the cost attribute; preference heterogeneity; and altruism. \ud \ud Chapter 2 shows how DCEs can be used to calculate WTP, using a DCE relating to Deep Vein Thrombosis (DVT). \ud \ud Chapter 3 uses data from a DCE applied to Menstrual disorder and Gynaecology patients. It evaluates an experimental method I developed to establish whether respondents might fail to factor in the monetary attribute into their DCE decision making, leading to hypothetical bias. \ud \ud Chapter 4 applies essentially the same DCE design but only analyses data from Gynaecology patients. \ud \ud Chapters 4-8 all use data obtained from a DCE relating to preferences for different allocation criteria for allocating kidneys for transplantation. Chapters 5 and 6 look at preference heterogeneity which is observable using interaction dummy variables (the issue of unobserved preference heterogeneity is considered in chapter 7). Chapter 5 establishes how marginal rates of substitution (MRS) differ between different respondent groups including renal patients, healthcare professionals, live donors / relatives of deceased donors, carers, and ethnic minority versus non-ethnic minority patients. Chapter 6 establishes how MRS differs between non-white ethnic minority patients versus other patients; South Asian patients versus other patients; and according to respondent gender. Chapter 7 of the thesis compares results from models which do not cater for unobserved preference heterogeneity, with results from models which do. Initially 2 basic models which do not cater for preference heterogeneity at all (because they do not include dummy variables) are applied including random effects logit and conditional logit. Then models catering for unobserved preference heterogeneity including Mixed Logit and a Latent Class Model (LCM) are used. Finally there is an analysis involving the application of conditional logit with interaction dummy variables. \ud \ud Chapter 8 of the thesis explores how preferences might differ according to how altruistic respondents are. It establishes how respondent preferences differ according to respondent self-disclosed perspective when answering DCEs. In other words whether they claimed to answer the DCE in terms of what would be best for me; what would be best for me and others; or what is best for others. \ud \ud Finally chapter 9 involves a discussion of the findings emerging from the thesis, and draws conclusions about the merits of material contained in it.

49. White Matter Changes Related to Subconcussive Impact Frequency during a Single Season of High School Football.

Author

Kuzminski SJ, Clark MD, Fraser MA, Haswell CC, Morey RA, Liu C, Choudhury KR, Guskiewicz KM, and Petrella JR

Subjects
Adolescent, Adult, Brain Injuries diagnostic imaging, Brain Injuries pathology, Diffusion Tensor Imaging, Head Injuries, Closed diagnostic imaging, Head Injuries, Closed pathology, Humans, Male, Pilot Projects, White Matter diagnostic imaging, White Matter pathology, Athletes, Brain Injuries etiology, Football injuries, Head Injuries, Closed etiology, White Matter injuries
Abstract

Background and Purpose: The effect of exposing the developing brain of a high school football player to subconcussive impacts during a single season is unknown. The purpose of this pilot study was to use diffusion tensor imaging to assess white matter changes during a single high school football season, and to correlate these changes with impacts measured by helmet accelerometer data and neurocognitive test scores collected during the same period., Materials and Methods: Seventeen male athletes (mean age, 16 ± 0.73 years) underwent MR imaging before and after the season. Changes in fractional anisotropy across the white matter skeleton were assessed with Tract-Based Spatial Statistics and ROI analysis., Results: The mean number of impacts over a 10-g threshold sustained was 414 ± 291. Voxelwise analysis failed to show significant changes in fractional anisotropy across the season or a correlation with impact frequency, after correcting for multiple comparisons. ROI analysis showed significant ( P < .05, corrected) decreases in fractional anisotropy in the fornix-stria terminalis and cingulum hippocampus, which were related to impact frequency. The effects were strongest in the fornix-stria terminalis, where decreases in fractional anisotropy correlated with worsening visual memory., Conclusions: Our findings suggest that subclinical neurotrauma related to participation in American football may result in white matter injury and that alterations in white matter tracts within the limbic system may be detectable after only 1 season of play at the high school level., (© 2018 by American Journal of Neuroradiology.)

Published
2018
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50. Group treatments for sensitive health care problems: a randomised controlled trial of group versus individual physiotherapy sessions for female urinary incontinence.

Author

Lamb SE, Pepper J, Lall R, Jørstad-Stein EC, Clark MD, Hill L, and Fereday-Smith J

Subjects
Adult, Aged, Cost-Benefit Analysis, Exercise Therapy economics, Female, Humans, Middle Aged, Patient Preference, Physical Therapy Modalities economics, Probability, Professional-Patient Relations, Severity of Illness Index, Sickness Impact Profile, Single-Blind Method, State Medicine, Stress, Psychological, Treatment Outcome, United Kingdom, Urinary Incontinence diagnosis, Urinary Incontinence psychology, Exercise Therapy methods, Health Care Costs, Quality of Life, Urinary Incontinence economics, Urinary Incontinence rehabilitation
Abstract

Background: The aim was to compare effectiveness of group versus individual sessions of physiotherapy in terms of symptoms, quality of life, and costs, and to investigate the effect of patient preference on uptake and outcome of treatment., Methods: A pragmatic, multi-centre randomised controlled trial in five British National Health Service physiotherapy departments. 174 women with stress and/or urge incontinence were randomised to receive treatment from a physiotherapist delivered in a group or individual setting over three weekly sessions. Outcome were measured as Symptom Severity Index; Incontinence-related Quality of Life questionnaire; National Health Service costs, and out of pocket expenses., Results: The majority of women expressed no preference (55%) or preference for individual treatment (36%). Treatment attendance was good, with similar attendance with both service delivery models. Overall, there were no statistically significant differences in symptom severity or quality of life outcomes between the models. Over 85% of women reported a subjective benefit of treatment, with a slightly higher rating in the individual compared with the group setting. When all health care costs were considered, average cost per patient was lower for group sessions (Mean cost difference 52.91 pounds 95%, confidence interval ( 25.82 pounds- 80.00 pounds))., Conclusion: Indications are that whilst some women may have an initial preference for individual treatment, there are no substantial differences in the symptom, quality of life outcomes or non-attendance. Because of the significant difference in mean cost, group treatment is recommended., Trial Registration Number: ISRCTN 16772662.

Published
2009
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