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Sökning: WFRF:(O''Brien John)

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  • Bentley, Michael J., et al. (författare)
  • A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum
  • 2014
  • Ingår i: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 100, s. 1-9
  • Tidskriftsartikel (refereegranskat)abstract
    • A robust understanding of Antarctic Ice Sheet deglacial history since the Last Glacial Maximum is important in order to constrain ice sheet and glacial-isostatic adjustment models, and to explore the forcing mechanisms responsible for ice sheet retreat. Such understanding can be derived from a broad range of geological and glaciological datasets and recent decades have seen an upsurge in such data gathering around the continent and Sub-Antarctic islands. Here, we report a new synthesis of those datasets, based on an accompanying series of reviews of the geological data, organised by sector. We present a series of timeslice maps for 20 ka, 15 ka, 10 ka and 5 ka, including grounding line position and ice sheet thickness changes, along with a clear assessment of levels of confidence. The reconstruction shows that the Antarctic Ice sheet did not everywhere reach the continental shelf edge at its maximum, that initial retreat was asynchronous, and that the spatial pattern of deglaciation was highly variable, particularly on the inner shelf. The deglacial reconstruction is consistent with a moderate overall excess ice volume and with a relatively small Antarctic contribution to meltwater pulse la. We discuss key areas of uncertainty both around the continent and by time interval, and we highlight potential priorities for future work. The synthesis is intended to be a resource for the modelling and glacial geological community. (C) 2014 The Authors. Published by Elsevier Ltd.
  • Cant, David J. H., et al. (författare)
  • Surface Properties of Nanocrystalline PbS Films Deposited at the Water-Oil Interface: A Study of Atmospheric Aging
  • 2015
  • Ingår i: Langmuir. - : The American Chemical Society (ACS). - 0743-7463. ; 31:4, s. 1445-1453
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanocrystalline thin films of PbS are obtained in a straightforward reaction by precipitation at the interface between toluene (containing a Pb precursor) and water (containing Na2S). Lead thiobiuret [Pb(SON(CN(i)Pr-2)(2))(2)] and lead diethyldithiocarbamate [Pb(S2CNEt2)(2)] precursors are used. The films are characterized by X-ray diffraction and electron microscopy, revealing typical particle sizes of 10-40 nm and preferred (200) orientation. Synchrotron-excited depth-profiling X-ray photoelectron spectroscopy (XPS) is used to determine the depth-dependent chemical composition as a function of surface aging in air for periods of up to 9 months. The as-synthesized films show a 1:1 Pb/S composition. Initial degradation occurs to form lead hydroxide and small quantities of surface-adsorbed -SH species. A lead-deficient Pb1-xS phase is produced as the aging proceeds. Oxidation of the sulfur occurs later to form sulfite and sulfate products that are highly localized at the surface layers of the nanocrystals. These species show logarithmic growth kinetics, demonstrating that the sulfite/sulfate layer acts to passivate the nanocrystals. Our results demonstrate that the initial reaction of the PbS nanocrystals (forming lead hydroxide) is incongruent. The results are discussed in the context of the use of PbS nanocrystals as light-harvesting elements in next-generation solar technology.
  • Caro, J. J., et al. (författare)
  • Economic implications of extended-release metoprolol succinate for heart failure in the MERIT-HF trial: a US perspective of the MERIT-HF trial
  • 2005
  • Ingår i: J Card Fail. - 1071-9164. ; 11:9, s. 647-56
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The MERIT-HF trial demonstrated improved survival and fewer hospitalizations for worsening heart failure with extended-release (ER) metoprolol succinate in patients with heart failure. This study sought to estimate the economic implications of this trial from a US perspective. METHODS AND RESULTS: A discrete event simulation was developed to examine the course of patients with heart failure. Characteristics of the population modeled, probabilities of hospitalization and death with standard therapy, and risk reductions with ER metoprolol succinate were obtained from Metoprolol CR/XL Randomized Intervention Trial in Chronic Heart Failure (MERIT-HF) and evaluated in weekly cycles. Direct medical costs were estimated from US databases in 2001 US dollars. Uncertainty in inputs was incorporated and analyses were carried out to estimate events prevented total and net costs. The model predicts that ER metoprolol succinate will prevent approximately 7 deaths and 15 hospitalizations from heart failure per 100 patients over 2 years. Compared with standard therapy alone, this translates to a cost reduction between $395 and $1112 per patient, depending on whether the costs of hospitalizations for other causes are included. Savings were maintained in 90% of the simulations. CONCLUSION: This analysis predicts that the positive effect of ER metoprolol succinate on mortality and morbidity demonstrated in MERIT-HF leads to substantial savings.
  • De Guio, François, et al. (författare)
  • Reproducibility and variability of quantitative magnetic resonance imaging markers in cerebral small vessel disease
  • Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : Nature Publishing Group. - 0271-678X. ; 36:8, s. 1319-1337
  • Forskningsöversikt (refereegranskat)abstract
    • Brain imaging is essential for the diagnosis and characterization of cerebral small vessel disease. Several magnetic resonance imaging markers have therefore emerged, providing new information on the diagnosis, progression, and mechanisms of small vessel disease. Yet, the reproducibility of these small vessel disease markers has received little attention despite being widely used in cross-sectional and longitudinal studies. This review focuses on the main small vessel disease-related markers on magnetic resonance imaging including: white matter hyperintensities, lacunes, dilated perivascular spaces, microbleeds, and brain volume. The aim is to summarize, for each marker, what is currently known about: (1) its reproducibility in studies with a scan-rescan procedure either in single or multicenter settings; (2) the acquisition-related sources of variability; and, (3) the techniques used to minimize this variability. Based on the results, we discuss technical and other challenges that need to be overcome in order for these markers to be reliably used as outcome measures in future clinical trials. We also highlight the key points that need to be considered when designing multicenter magnetic resonance imaging studies of small vessel disease.
  • Dichgans, Martin, et al. (författare)
  • METACOHORTS for the study of vascular disease and its contribution to cognitive decline and neurodegeneration : An initiative of the Joint Programme for Neurodegenerative Disease Research
  • 2016
  • Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260. ; 12:12, s. 1235-1249
  • Tidskriftsartikel (refereegranskat)abstract
    • Dementia is a global problem and major target for health care providers. Although up to 45% of cases are primarily or partly due to cerebrovascular disease, little is known of these mechanisms or treatments because most dementia research still focuses on pure Alzheimer's disease. An improved understanding of the vascular contributions to neurodegeneration and dementia, particularly by small vessel disease, is hampered by imprecise data, including the incidence and prevalence of symptomatic and clinically “silent” cerebrovascular disease, long-term outcomes (cognitive, stroke, or functional), and risk factors. New large collaborative studies with long follow-up are expensive and time consuming, yet substantial data to advance the field are available. In an initiative funded by the Joint Programme for Neurodegenerative Disease Research, 55 international experts surveyed and assessed available data, starting with European cohorts, to promote data sharing to advance understanding of how vascular disease affects brain structure and function, optimize methods for cerebrovascular disease in neurodegeneration research, and focus future research on gaps in knowledge. Here, we summarize the results and recommendations from this initiative. We identified data from over 90 studies, including over 660,000 participants, many being additional to neurodegeneration data initiatives. The enthusiastic response means that cohorts from North America, Australasia, and the Asia Pacific Region are included, creating a truly global, collaborative, data sharing platform, linked to major national dementia initiatives. Furthermore, the revised World Health Organization International Classification of Diseases version 11 should facilitate recognition of vascular-related brain damage by creating one category for all cerebrovascular disease presentations and thus accelerate identification of targets for dementia prevention.
  • Duncan, Gordon W, et al. (författare)
  • Gray and white matter imaging : A biomarker for cognitive impairment in early Parkinson's disease?
  • Ingår i: Movement Disorders. - : John Wiley and Sons. - 0885-3185. ; 31:1, s. 10-103
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The aim of this work was to investigate the cortical and white matter changes that underlie cognitive impairment in patients with incident Parkinson's disease (PD) disease using voxel-based morphometry and diffusion tensor imaging.METHODS: Newly diagnosed nondemented PD (n = 125) and control subjects (n = 50) were recruited from the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation in Parkinson's Disease Study and completed cognitive assessments and 3T structural and diffusion tensor MR imaging. Voxel-based morphometry was performed to investigate the relationship between gray matter volume and cognitive ability. Microstructural white matter changes were assessed with diffusion tensor imaging measures of fractional anisotropy and mean diffusivity using tract-based spatial statistics.RESULTS: Increased mean diffusivity was observed bilaterally in subjects with PD, relative to controls (P = 0.019). Increased mean diffusivity was associated with performance on the semantic fluency and Tower of London tasks in frontal and parietal white matter tracts, including the cingulum, superior longitudinal fasciculus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus. There was no difference in total gray matter volume between groups; however, bilateral reductions in frontal and parietal gray matter volume were associated with reduced performance on measures of executive function in PD subjects.CONCLUSIONS: At the earliest stages of PD, regionally specific increases in central white matter mean diffusivity are present and suggest early axonal damage. Such changes are not accompanied by significant gray matter volume loss and are consistent with proposed models of pathological progression of the disease. Structural MRI, especially diffusion tensor imaging analysis, offers potential as a noninvasive biomarker reflecting cognitive impairment in PD.
  • Duncan, Gordon W, et al. (författare)
  • Health-related quality of life in early Parkinson's disease : the impact of nonmotor symptoms
  • Ingår i: Movement Disorders. - : John Wiley and Sons. - 0885-3185. ; 29:2, s. 195-202
  • Tidskriftsartikel (refereegranskat)abstract
    • Nonmotor symptoms (NMS) are common in patients with established Parkinson's disease (PD) and have a major impact upon quality of life. We investigated the significance of NMS in relation to health-related quality of life (HRQoL) in patients with newly diagnosed PD. Patients and healthy controls were recruited as part of the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation in Parkinson's Disease Study. Prevalence of NMS was determined with the Non-Motor Symptom Questionnaire. HRQoL was recorded with the 39-item Parkinson's Disease Quality of Life Questionnaire (PDQ-39). Further assessments included measures of motor disability, depression, sleep, and cognition. One hundred and fifty-eight patients with newly diagnosed PD and 99 controls participated in this cross-sectional study. Patients reported greater numbers of NMS than controls (mean 8.3 ± 4.3 versus 2.8 ± 2.5 symptoms; P < 0.001). Patients reported lowest HRQoL in the domains assessing bodily discomfort, mobility, and activities of daily living. Motor and nonmotor symptoms impacted negatively upon HRQoL scores. Patients with the postural instability and gait difficulty motor subtype reported worse HRQoL, compared with those with tremor-dominant disease. Depression (P < 0.001), incomplete bowel emptying (P < 0.001), anxiety (P < 0.001), impaired concentration (P < 0.001), memory complaints (P < 0.001), and insomnia (P = 0.001) had the greatest negative impact upon HRQoL. NMS are common in patients with early PD and represent a significant cause of poorer health-related quality of life. Cognitive, neuropsychiatric, and sleep disturbances are particularly associated with reduced well-being. Screening and management of these symptoms should be prioritized at the time of diagnosis.
  • Duncan, Gordon William, et al. (författare)
  • The incidence of Parkinson's disease in the North-East of England
  • Ingår i: Age and Ageing. - : Oxford University Press. - 1468-2834. ; 43:2, s. 63-257
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Parkinson's disease is a common disorder among older people. Accurate epidemiological information is essential to identify possible aetiological factors, plan health services and set priorities for medical research.OBJECTIVE: to determine the incidence of idiopathic Parkinson's disease in a defined geographical area in the North-East of England.METHODS: using a prospective, longitudinal design, we sought to identify every new case of Parkinson's disease arising in the Newcastle and Gateshead area in the North-East of England. The base population comprised 488 576 individuals and multiple sources of case ascertainment were employed. All the patients with newly diagnosed idiopathic Parkinson's disease or parkinsonism between 1 June 2009 and 31 May 2011 were invited to participate. Patients were examined by a specialist and followed longitudinally to permit diagnostic review.RESULTS: we identified 257 potential cases, of whom 181 had suspected idiopathic Parkinson's disease. After a follow-up period of 18 months, 155 patients retained a clinical diagnosis of probable Parkinson's disease. The mean age at diagnosis was 72.4 ± 10 years. The crude incidence of PD in Newcastle and Gateshead was 15.9 per 100 000 persons per year (95% CI: 13.4-18.4). Age-standardised to the European population the incidence of Parkinson's disease was 12.0 per 100 000 (95% CI: 10.1-14.0). We found a higher crude incidence among men 17.7 per 100 000 (95% CI: 14.0-21.4) than women 14.0 per 100 000 (95% CI: 10.7-17.4).CONCLUSION: in this prospective longitudinal study, the incidence rate of Parkinson's disease in North-East England is similar to that of other modern European and American studies.
  • Fazey, Ioan, et al. (författare)
  • Ten essentials for action-oriented and second order energy transitions, transformations and climate change research
  • 2018
  • Ingår i: Energy Research and Social Science. - : Elsevier. - 2214-6296 .- 2214-6326. ; 40, s. 54-70
  • Forskningsöversikt (refereegranskat)abstract
    • The most critical question for climate research is no longer about the problem, but about how to facilitate the transformative changes necessary to avoid catastrophic climate-induced change. Addressing this question, however, will require massive upscaling of research that can rapidly enhance learning about transformations. Ten essentials for guiding action-oriented transformation and energy research are therefore presented, framed in relation to second-order science. They include: (1) Focus on transformations to low-carbon, resilient living; (2) Focus on solution processes; (3) Focus on ‘how to’ practical knowledge; (4) Approach research as occurring from within the system being intervened; (5) Work with normative aspects; (6) Seek to transcend current thinking; (7) Take a multi-faceted approach to understand and shape change; (8) Acknowledge the value of alternative roles of researchers; (9) Encourage second-order experimentation; and (10) Be reflexive. Joint application of the essentials would create highly adaptive, reflexive, collaborative and impact-oriented research able to enhance capacity to respond to the climate challenge. At present, however, the practice of such approaches is limited and constrained by dominance of other approaches. For wider transformations to low carbon living and energy systems to occur, transformations will therefore also be needed in the way in which knowledge is produced and used.
  • Ihara, Masafumi, et al. (författare)
  • Quantification of myelin loss in frontal lobe white matter in vascular dementia, Alzheimer's disease, and dementia with Lewy bodies
  • 2010
  • Ingår i: Acta Neuropathologica. - : Springer. - 1432-0533. ; 119:5, s. 579-589
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to characterize myelin loss as one of the features of white matter abnormalities across three common dementing disorders. We evaluated post-mortem brain tissue from frontal and temporal lobes from 20 vascular dementia (VaD), 19 Alzheimer's disease (AD) and 31 dementia with Lewy bodies (DLB) cases and 12 comparable age controls. Images of sections stained with conventional luxol fast blue were analysed to estimate myelin attenuation by optical density. Serial adjacent sections were then immunostained for degraded myelin basic protein (dMBP) and the mean percentage area containing dMBP (%dMBP) was determined as an indicator of myelin degeneration. We further assessed the relationship between dMBP and glutathione S-transferase (a marker of mature oligodendrocytes) immunoreactivities. Pathological diagnosis significantly affected the frontal but not temporal lobe myelin attenuation: myelin density was most reduced in VaD compared to AD and DLB, which still significantly exhibited lower myelin density compared to ageing controls. Consistent with this, the degree of myelin loss was correlated with greater %dMBP, with the highest %dMBP in VaD compared to the other groups. The %dMBP was inversely correlated with the mean size of oligodendrocytes in VaD, whereas it was positively correlated with their density in AD. A two-tier regression model analysis confirmed that the type of disorder (VaD or AD) determines the relationship between %dMBP and the size or density of oligodendrocytes across the cases. Our findings, attested by the use of three markers, suggest that myelin loss may evolve in parallel with shrunken oligodendrocytes in VaD but their increased density in AD, highlighting partially different mechanisms are associated with myelin degeneration, which could originate from hypoxic-ischaemic damage to oligodendrocytes in VaD whereas secondary to axonal degeneration in AD.
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