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Search Results: 1 - 10 of 264216 matches for " Megan E. O'Connell "
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Clinical Correlates of Awareness for Balance, Function, and Memory: Evidence for the Modality Specificity of Awareness
Megan E. O'Connell,Vanina Dal Bello-Haas,Margaret Crossley,Debra Morgan
Journal of Aging Research , 2014, DOI: 10.1155/2014/674716
Abstract: Awareness in dementia is increasingly recognized not only as multifactorial, but also as domain specific. We demonstrate differential clinical correlates for awareness of daily function, awareness of memory, and the novel exploration of awareness of balance. Awareness of function was higher for participants with mild cognitive impairment (aMCI and non-aMCI) than for those with dementia (due to Alzheimer disease; AD and non-AD), whereas awareness of memory was higher for both non-aMCI and non-AD dementia patients than for those with aMCI or AD. Balance awareness did not differ based on diagnostic subgroup. Awareness of function was associated with instrumental activities of daily living and caregiver burden. In contrast, awareness of balance was associated with fall history, balance confidence, and instrumental activities of daily living. Clinical correlates of awareness of memory depended on diagnostic group: associations held with neuropsychological variables for non-AD dementia, but for patients with AD dementia, depression and instrumental activities of daily living were clinical correlates of memory awareness. Together, these data provide support for the hypothesis that awareness and dementia are not unitary and are, instead, modality specific. 1. Introduction Unawareness, lack of insight, or anosognosia refers to impaired awareness in persons with dementia [1–7]. Awareness is multifactorial and likely modular [4, 8–10], with each domain separable and potentially unique. Most of the literature on awareness in persons with dementia describes the clinical correlates of one awareness domain (reviews by [1, 4, 11]), but the few studies that have contrasted awareness for different domains have found differential patterns of clinical correlates [12–15]. This paper provides further support for the modality specific nature of awareness in dementia by contrasting the clinical correlates for awareness of balance in addition to more commonly measured awareness of day-to-day function and memory. Awareness quantification remains elusive, and there is no consensus method for measuring awareness (e.g., [4, 9]). Awareness has been measured with clinician ratings [16, 17]; or based on discrepancy between self-report versus clinicians’ impression [10] or versus informant report assessed with interview [10, 18] or questionnaires [7, 12, 14, 19–21]; or discrepancy between self-report and objective performance [21, 22], which, depending on the task, measures self-monitoring or metacognitive abilities [3]. Each assessment method has limitations: Clare et al. [21] detail
Pahs, Ionized Gas, and Molecular Hydrogen in Brightest Cluster Galaxies of Cool Core Clusters of Galaxies
Megan Donahue,Geneviève E. de Messières,Robert W. O'Connell,G. Mark Voit,Aaron Hoffer,Brian R. McNamara,Paul E. J. Nulsen
Physics , 2011, DOI: 10.1088/0004-637X/732/1/40
Abstract: We present measurements of 5-25 {\mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of 9 cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally-excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H2 rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as somewhat higher ratios of 70 {\mu}m / 24 {\mu}m luminosities. Our analysis suggests that while star formation processes dominate the heating of the dust and PAHs, a heating process consistent with suprathermal electron heating from the hot gas, distinct from star formation, is heating the molecular gas and contributing to the heating of the ionized gas in the galaxies. The survival of PAHs and dust suggests that dusty gas is somehow shielded from significant interaction with the X-ray gas.
Structural Characterization of Two Metastable ATP-Bound States of P-Glycoprotein
Megan L. O’Mara, Alan E. Mark
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091916
Abstract: ATP Binding Cassette (ABC) transporters couple the binding and hydrolysis of ATP to the transport of substrate molecules across the membrane. The mechanism by which ATP binding and/or hydrolysis drives the conformational changes associated with substrate transport has not yet been characterized fully. Here, changes in the conformation of the ABC export protein P-glycoprotein on ATP binding are examined in a series of molecular dynamics simulations. When one molecule of ATP is placed at the ATP binding site associated with each of the two nucleotide binding domains (NBDs), the membrane-embedded P-glycoprotein crystal structure adopts two distinct metastable conformations. In one, each ATP molecule interacts primarily with the Walker A motif of the corresponding NBD. In the other, the ATP molecules interacts with both Walker A motif of one NBD and the Signature motif of the opposite NBD inducing the partial dimerization of the NBDs. This interaction is more extensive in one of the two ATP binding site, leading to an asymmetric structure. The overall conformation of the transmembrane domains is not altered in either of these metastable states, indicating that the conformational changes associated with ATP binding observed in the simulations in the absence of substrate do not lead to the outward-facing conformation and thus would be insufficient in themselves to drive transport. Nevertheless, the metastable intermediate ATP-bound conformations observed are compatible with a wide range of experimental cross-linking data demonstrating the simulations do capture physiologically important conformations. Analysis of the interaction between ATP and its cofactor Mg2+ with each NBD indicates that the coordination of ATP and Mg2+ differs between the two NBDs. The role structural asymmetry may play in ATP binding and hydrolysis is discussed. Furthermore, we demonstrate that our results are not heavily influenced by the crystal structure chosen for initiation of the simulations.
The Value of Positive Pressure Ventilations for Clients in Acute Respiratory Distress as a Result of Cardiac and Pulmonary Issues  [PDF]
Patrick OConnell
Open Journal of Respiratory Diseases (OJRD) , 2015, DOI: 10.4236/ojrd.2015.52005
Abstract: Objective: Research was conducted to examine benefits to using non-invasive ventilation (NIV) or continuous positive airway pressure (CPAP) early in the treatment of respiratory distress caused by pulmonary edema, chronic obstructive pulmonary disease (COPD) and asthma. Limitations to successful NIV and CPAP therapy were evaluated to determine how prolonged initiation of treatment may lead to hypoxemia (decreased oxygen in the blood) and hypercapnia (increased carbon dioxide in the blood) resulting in poor outcomes. Method: Reviews of literature from nursing and allied health data bases (CINAHL and ProQuest) with terms pulmonary edema, positive pressure device and non-invasive ventilation from 2010 to 2014 were used. Studies were conducted in the hospital and prehospital settings. Results: The literature search located 7 articles from CINAHL and 25 articles from ProQuest. A total of 6 of these articles were analyzed. Additional sources of data were obtained from Ignatavicius and Workman (2013) Medical-Surgical Nursing Patient-Centered Collaborative Care 7th edition and American Journal of Nursing (02/2013) Volume 113: 2. Conclusion: All of the articles concluded that early initiation of continuous positive airway pressure ventilations in the short-term was beneficial; however, late initiation of therapy required additional interventions. The studies indicated that early use of positive airway pressure in acute respiratory distress improved breath rate, heart rate and blood pressure. The use of positive airway pressure for respiratory distress may decrease the need for endotracheal intubation.
Undergraduate radiology teaching from the student’s perspective
Christiane M. Nyhsen,Laura J. Steinberg,Janice E. OConnell
Insights into Imaging , 2013, DOI: 10.1007/s13244-012-0206-8
Abstract: There is a call for reliable, up-to-date open access electronic resources for medical students.
A Regionalised Neyman-Scott Model of Rainfall with Convective and Stratiform Cells
P. S. P. Cowpertwait,P. E. O'Connell
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 1997,
Abstract: A single-site Neyman-Scott Poisson cluster model of rainfall, with convective and stratiform cells, is fitted to data for 112 sites scattered throughout the UK using harmonic variables to account for seasonality. The model is regionalised by regressing the estimates of the harmonic variables on site dependent variables (e.g. altitude) to enable rainfall to be simulated at any ungauged site in the UK. An assessment of the residual errors indicates that the regression models can be used with reasonable confidence for urban sites. Furthermore, the regional variations of the model parameter estimates are found to be in agreement with meteorological knowledge and observation. Simulated I h extreme rainfalls are found to compare favourably with observed historical values, although some lack-of-fit is evident for higher aggregation levels.
A stochastic rainfall model for the assessment of regional water resource systems under changed climatic condition
H. J. Fowler,C. G. Kilsby,P. E. OConnell
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2000,
Abstract: A stochastic model is developed for the synthesis of daily precipitation using conditioning by weather types. Daily precipitation statistics at multiple sites within the region of Yorkshire, UK, are linked to objective Lamb weather types (LWTs) and used to split the region into three distinct precipitation sub-regions. Using a variance minimisation criterion, the 27 LWTs are clustered into three physically realistic groups or ‘states'. A semi-Markov chain model is used to synthesise long sequences of weather states, maintaining the observed persistence and transition probabilities. The Neyman-Scott Rectangular Pulses (NSRP) model is then fitted for each weather state, using a defined summer and winter period. The combined model reproduces key aspects of the historic precipitation regime at temporal resolutions down to the hourly level. Long synthetic precipitation series are useful in the sensitivity analysis of water resource systems under current and changed climatic conditions. This methodology enables investigation of the impact of variations in weather type persistence or frequency. In addition, rainfall model statistics can be altered to simulate instances of increased intensity or proportion of dry days for example, for individual weather groups. The input of such data into a water resource model, simulating potential atmospheric circulation changes, will provide a valuable tool for future planning of water resource systems. The ability of the model to operate at an hourly level also allows its use in a wider range of hydrological impact studies, e.g. variations in river flows, flood risk estimation etc. Keywords: water resources; climate change; impacts; stochastic rainfall model; Lamb weather types
Climatic and basin factors affecting the flood frequency curve: PART II – A full sensitivity analysis based on the continuous simulation approach combined with a factorial experimental design
M. Franchini,A. M. Hashemi,P. E. OConnell
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2000,
Abstract: The sensitivity analysis described in Hashemi et al. (2000) is based on one-at-a-time perturbations to the model parameters. This type of analysis cannot highlight the presence of parameter interactions which might indeed affect the characteristics of the flood frequency curve (ffc) even more than the individual parameters. For this reason, the effects of the parameters of the rainfall, rainfall runoff models and of the potential evapotranspiration demand on the ffc are investigated here through an analysis of the results obtained from a factorial experimental design, where all the parameters are allowed to vary simultaneously. This latter, more complex, analysis confirms the results obtained in Hashemi et al. (2000) thus making the conclusions drawn there of wider validity and not related strictly to the reference set selected. However, it is shown that two-factor interactions are present not only between different pairs of parameters of an individual model, but also between pairs of parameters of different models, such as rainfall and rainfall-runoff models, thus demonstrating the complex interaction between climate and basin characteristics affecting the ffc and in particular its curvature. Furthermore, the wider range of climatic regime behaviour produced within the factorial experimental design shows that the probability distribution of soil moisture content at the storm arrival time is no longer sufficient to explain the link between the perturbations to the parameters and their effects on the ffc, as was suggested in Hashemi et al. (2000). Other factors have to be considered, such as the probability distribution of the soil moisture capacity, and the rainfall regime, expressed through the annual maximum rainfalls over different durations. Keywords: Monte Carlo simulation; factorial experimental design; analysis of variance (ANOVA)
Climatic and basin factors affecting the flood frequency curve: PART I – A simple sensitivity analysis based on the continuous simulation approach
A. M. Hashemi,M. Franchini,P. E. OConnell
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2000,
Abstract: Regionalized and at-site flood frequency curves exhibit considerable variability in their shapes, but the factors controlling the variability (other than sampling effects) are not well understood. An application of the Monte Carlo simulation-based derived distribution approach is presented in this two-part paper to explore the influence of climate, described by simulated rainfall and evapotranspiration time series, and basin factors on the flood frequency curve (ffc). The sensitivity analysis conducted in the paper should not be interpreted as reflecting possible climate changes, but the results can provide an indication of the changes to which the flood frequency curve might be sensitive. A single site Neyman Scott point process model of rainfall, with convective and stratiform cells (Cowpertwait, 1994; 1995), has been employed to generate synthetic rainfall inputs to a rainfall runoff model. The time series of the potential evapotranspiration (ETp) demand has been represented through an AR(n) model with seasonal component, while a simplified version of the ARNO rainfall-runoff model (Todini, 1996) has been employed to simulate the continuous discharge time series. All these models have been parameterised in a realistic manner using observed data and results from previous applications, to obtain ‘reference’ parameter sets for a synthetic case study. Subsequently, perturbations to the model parameters have been made one-at-a-time and the sensitivities of the generated annual maximum rainfall and flood frequency curves (unstandardised, and standardised by the mean) have been assessed. Overall, the sensitivity analysis described in this paper suggests that the soil moisture regime, and, in particular, the probability distribution of soil moisture content at the storm arrival time, can be considered as a unifying link between the perturbations to the several parameters and their effects on the standardised and unstandardised ffcs, thus revealing the physical mechanism through which their influence is exercised. However, perturbations to the parameters of the linear routing component affect only the unstandardised ffc. In Franchini et al. (2000), the sensitivity analysis of the model parameters has been assessed through an analysis of variance (ANOVA) of the results obtained from a formal experimental design, where all the parameters are allowed to vary simultaneously, thus providing deeper insight into the interactions between the different factors. This approach allows a wider range of climatic and basin conditions to be analysed and reinforces the result
Training and HIV-Treatment Scale-Up: Establishing an Implementation Research Agenda
Elizabeth A McCarthy ,Megan E O'Brien,William R Rodriguez
PLOS Medicine , 2006, DOI: 10.1371/journal.pmed.0030304
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