oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 3 )

2019 ( 66 )

2018 ( 70 )

2017 ( 71 )

Custom range...

Search Results: 1 - 10 of 35849 matches for " Karen Thomas "
All listed articles are free for downloading (OA Articles)
Page 1 /35849
Display every page Item
Phantom study of the impact of adaptive statistical iterative reconstruction (ASiRTM) on image quality for paediatric computed tomography  [PDF]
Angjelina Protik, Karen Thomas, Paul Babyn, Nancy L. Ford
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.512A100
Abstract:

Quantitative analysis of image quality will be helpful for designing ASiRTM-enhanced paediatric CT protocols, balancing image quality and radiation dose. Catphan600 phantom studies were performed on a GE Discovery HD750 64-slice CT scanner. Images were reconstructed with 0% - 100% ASiRTM (tube current 150 mA, variable kVp 80 - 140) in order to determine the optimal ASiRTM-Filtered Back Projection (FBP) blend. Images reconstructed with a 50% ASiRTM-50% FBP blend were compared to FBP images (0% ASiRTM) over a wide range of kVp (80 - 140) and mA (10 - 400) values. Measurements of image noise, CT number accuracy and uniformity, spatial and contrast resolution, and low contrast detectability were performed on axial and reformatted coronal images. Improvements in CNR, low contrast detectability and radial uniformity were observed in ASiRTM images compared to FBP images. 50% ASiRTM was associated with a 26% - 30% reduction in image noise. Changes in noise texture were observed at higher %

Does Resampled Image Data Offer Quantitative Image Quality Benefit for Pediatric CT?  [PDF]
Nancy L. Ford, Angjelina Protik, Paul Babyn, Karen Thomas
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.76036
Abstract: Acquiring CT images with thin slices can improve resolution and detectability, but cause an increase in the image noise. To compensate for the additional image noise, the kVp or mA can be increased, which carries a dose penalty to the patient. We investigate the image quality achieved in MPR images reformatted from different slice thicknesses 0.625 mm and 5 mm, to determine if a thicker slice could be resampled to smaller thickness with minimal loss of image information. Catphan?600 phantom was imaged using selected kVp/mA settings (80 kVp/250 mA, 100 kVp/ 150 mA and 120 kVp/200 mA) to generate slices with thicknesses of 0.625 mm and 5 mm using a GE Discovery HD750 64-slice CT scanner to investigate the impact of the acquisition slice thickness on the overall image quality in MPRs. Measurements of image noise, uniformity, contrast-to-noise ratio (CNR), low contrast detectability and limiting spatial resolution were performed on axial and coronal multiplanar reformatted images (MPRs). Increased noise, reduced contrast-to-noise ratio, and improved limiting spatial resolution and low contrast detection were observed in 2 mm coronal MPRs generated with 0.625 mm thin slices when compared to the MPRs from 5 mm thick slices. If the 2 mm coronal MPRs acquired with 5 mm slices are resampled to 0.6 mm slice thickness, the reductions in limiting resolution and low contrast detection are compensated, although with reduced uniformity and increased image noise. Thick slice image acquisitions yield better CNR and less noise in the images, whereas thin slices exhibited improved spatial resolution and low contrast detectability. Retrospectively resampling into thinner slices before obtaining the coronal MPRs provided a balance between image smoothness and identifying fine image detail. Which approach provides the optimal image quality may also depend on the imaging task, size and composition of the features of interest, and radiologist preference.
Pilot study: rapidly cycling hypobaric pressure improves pain after 5 days in adiposis dolorosa
Karen L Herbst, Thomas Rutledge
Journal of Pain Research , 2010, DOI: http://dx.doi.org/10.2147/JPR.S12351
Abstract: t study: rapidly cycling hypobaric pressure improves pain after 5 days in adiposis dolorosa Original Research (5047) Total Article Views Authors: Karen L Herbst, Thomas Rutledge Published Date August 2010 Volume 2010:3 Pages 147 - 153 DOI: http://dx.doi.org/10.2147/JPR.S12351 Karen L Herbst1, Thomas Rutledge2 1Department of Medicine, University of California, San Diego, California, USA; 2Department of Psychiatry, University of California, San Diego, California, USA Abstract: Adiposis dolorosa (AD) is a rare disorder of painful nodular subcutaneous fat -accompanied by fatigue, difficulty with weight loss, inflammation, increased fluid in -adipose -tissue (lipedema and lymphedema), and hyperalgesia. Sequential compression relieves -lymphedema pain; we therefore hypothesized that whole body cyclic pneumatic hypobaric compression may relieve pain in AD. To avoid exacerbating hyperalgesia, we utilized a touch-free method, which is delivered via a high-performance altitude simulator, the Cyclic Variations in Altitude ConditioningTM (CVACTM) process. As a pilot study, 10 participants with AD completed pain and quality of life questionnaires before and after 20–40 minutes of CVAC process daily for 5 days. Participants lost weight (195.5 ± 17.6–193.8 ± 17.3 lb; P = 0.03), and bioimpedance significantly decreased (510 ± 36–490 ± 38 ohm; P = 0.01). There was a significant decrease in scores on the Pain Catastrophizing Scale (P = 0.039), in average (P = 0.002), highest (P = 0.029), lowest (P = 0.04), and current pain severity (P = 0.02) on the Visual Analogue Scale, but there was no change in pain quality by the McGill Pain Questionnaire. There were no significant changes in total and physical SF-36 scores, but the mental score improved significantly (P = 0.049). There were no changes in the Pain Disability Index or Pittsburgh Sleep Quality Index. These data present a potential, new, noninvasive means of treating pain in AD by whole body pneumatic compression as part of the CVAC process. Although randomized, controlled trials are needed to confirm these data, the CVAC process could potentially help in treating AD pain and other chronic pain disorders.
Getting to Know Library Users’ Needs — Experimental Ways to User-centred Library Innovation
Karen Harbo,Thomas Vibjerg Hansen
Liber Quarterly : The Journal of European Research Libraries , 2012,
Abstract: ‘Meeting the User’ is a programme committee under the Danish Electronic Research Library. As a development group at a national level we see our role as facilitating an innovative culture within academic libraries, focusing on users’ needs and the way libraries meet them. In collaboration with a consultancy firm, the committee organized a travelling workshop in four cities in 2010. The workshop introduced practical ways for library staff to get to know their users’ needs for services and was based on anthropological methods. The travelling workshop was part of a larger project called ‘A Journey of Discovery in Danish Library User Land’ (translated from Danish Brugerkaravanen), which also included a national thematic day, a blog and the publication of a method guide. There is an ongoing need for academic libraries to improve their services. One strategy is to become more aware of the users’ needs. On the one hand we have libraries which give access to a lot of information, offer courses in information literacy and strive to be a part of the learning environment. On the other hand we are not always certain of the needs of our users. If libraries want to improve the way they serve their users’ needs, they must innovate their services, facilities and courses by building upon what you could call ‘user logic’ and not upon classical ‘library logic’. ‘User logic’ is that which is meaningful for the user instead of what is traditionally meaningful for a library. Finding out what the users’ needs are, requires methods to study the users. In order to discover the shortest route from knowledge via idea to action, we looked for methods that can be employed by librarians or library information specialists. This article describes how 110 librarians and information specialists acquired such methods in four cities and in four days, by means of a workshop structured like a guided tour through the land of library users. The goal of the article is to give other libraries inspiration for ideas, concepts and concrete tools to study user behaviour and become more aware of the user’s needs for service. The article contains a description of the above-mentioned methods, valuable experiences from the workshop, a presentation of the concept and concrete tools, discussion of the concept of user logic and library services, and the seven principles for human-centred innovation in relation to libraries, a short list of studies carried out by librarians and discussion of further perspectives.
Pilot study: rapidly cycling hypobaric pressure improves pain after 5 days in adiposis dolorosa
Karen L Herbst,Thomas Rutledge
Journal of Pain Research , 2010,
Abstract: Karen L Herbst1, Thomas Rutledge21Department of Medicine, University of California, San Diego, California, USA; 2Department of Psychiatry, University of California, San Diego, California, USAAbstract: Adiposis dolorosa (AD) is a rare disorder of painful nodular subcutaneous fat -accompanied by fatigue, difficulty with weight loss, inflammation, increased fluid in -adipose -tissue (lipedema and lymphedema), and hyperalgesia. Sequential compression relieves -lymphedema pain; we therefore hypothesized that whole body cyclic pneumatic hypobaric compression may relieve pain in AD. To avoid exacerbating hyperalgesia, we utilized a touch-free method, which is delivered via a high-performance altitude simulator, the Cyclic Variations in Altitude ConditioningTM (CVACTM) process. As a pilot study, 10 participants with AD completed pain and quality of life questionnaires before and after 20–40 minutes of CVAC process daily for 5 days. Participants lost weight (195.5 ± 17.6–193.8 ± 17.3 lb; P = 0.03), and bioimpedance significantly decreased (510 ± 36–490 ± 38 ohm; P = 0.01). There was a significant decrease in scores on the Pain Catastrophizing Scale (P = 0.039), in average (P = 0.002), highest (P = 0.029), lowest (P = 0.04), and current pain severity (P = 0.02) on the Visual Analogue Scale, but there was no change in pain quality by the McGill Pain Questionnaire. There were no significant changes in total and physical SF-36 scores, but the mental score improved significantly (P = 0.049). There were no changes in the Pain Disability Index or Pittsburgh Sleep Quality Index. These data present a potential, new, noninvasive means of treating pain in AD by whole body pneumatic compression as part of the CVAC process. Although randomized, controlled trials are needed to confirm these data, the CVAC process could potentially help in treating AD pain and other chronic pain disorders.Keywords: bioimpedance, chronic pain, lipedema
Extrastriatal Dopaminergic Circuits of the Basal Ganglia
Karen S. Rommelfanger,Thomas Wichmann
Frontiers in Neuroanatomy , 2010, DOI: 10.3389/fnana.2010.00139
Abstract: The basal ganglia are comprised of the striatum, the external and internal segment of the globus pallidus (GPe and GPi, respectively), the subthalamic nucleus (STN), and the substantia nigra pars compacta and reticulata (SNc and SNr, respectively). Dopamine has long been identified as an important modulator of basal ganglia function in the striatum, and disturbances of striatal dopaminergic transmission have been implicated in diseases such as Parkinson’s disease (PD), addiction and attention deficit hyperactivity disorder. However, recent evidence suggests that dopamine may also modulate basal ganglia function at sites outside of the striatum, and that changes in dopaminergic transmission at these sites may contribute to the symptoms of PD and other neuropsychiatric disorders. This review summarizes the current knowledge of the anatomy, functional effects and behavioral consequences of the dopaminergic innervation to the GPe, GPi, STN, and SNr. Further insights into the dopaminergic modulation of basal ganglia function at extrastriatal sites may provide us with opportunities to develop new and more specific strategies for treating disorders of basal ganglia dysfunction.
A New Approach for Safe Tube Thoracostomy Insertion: An Objective and Subjective Comparison versus Established Techniques  [PDF]
Alex Doyle, Thomas White, Anna Hutton, Karen Mcguire, Parvez Moondi, Peter Young
International Journal of Clinical Medicine (IJCM) , 2014, DOI: 10.4236/ijcm.2014.52010
Abstract:

Introduction: Tube thoracostomy is an invasive procedure, which may result in life-threatening injury to major organs and blood vessels. We propose a new approach for inserting tube thoracostomies to improve the safety of this procedure, termed guided blunt dissection. In this article, we compared the safety of this new approach with traditional blunt dissection and two commercially available Seldinger tube thoracostomy kits in an ex vivo model. Methods: We recruited 32 clinicians from a variety of medical specialties with a range of experience in performing tube thoracostomy. Each clinician was required to perform tube thoracostomy using all four approaches in a randomised order. Objectively, each insertion was categorised as “safe” if the lung remained intact and “unsafe” if the lung deflated. Subjectively, participants were asked to rank each approach in order of perceived safety on a four-point scale. Statistical analysis was performed using a Fisher’s exact test. Results: Objectively, guided blunt dissection was significantly safer than both Seldinger approaches (p < 0.0001), but not traditional blunt dissection (p = 0.71). Subjectively, none of the approaches were felt to be superior. Conclusions: These data support the conclusions that, in this

Inducing mineral precipitation in groundwater by addition of phosphate
Karen E Wright, Thomas Hartmann, Yoshiko Fujita
Geochemical Transactions , 2011, DOI: 10.1186/1467-4866-12-8
Abstract: The general progression of mineral precipitation was similar under all of the study conditions, with initial formation of amorphous calcium phosphate, and transformation to poorly crystalline hydroxylapatite (HAP) within one week. The presence of the bacterial cells appeared to delay precipitation, although by the end of the experiments the overall extent of precipitation was similar for all treatments. The stoichiometry of the final precipitates as well as Rietveld structure refinement using x-ray diffraction data indicated that the presence of organic acids and bacterial cells resulted in an increasing a and decreasing c lattice parameter, with the higher concentration of cells resulting in the greatest distortion. Uptake of Sr into the solids was decreased in the treatments with cells and organic acids, compared to the control.Our results suggest that the minerals formed initially during an engineered precipitation application for trace element sequestration may not be the ones that control long-term immobilization of the contaminants. In addition, the presence of bacterial cells appears to be associated with delayed HAP precipitation, changes in the lattice parameters, and reduced incorporation of trace elements as compared to cell-free systems. Schemes to remediate groundwater contaminated with trace metals that are based on enhanced phosphate mineral precipitation may need to account for these phenomena, particularly if the remediation approach relies on enhancement of in situ microbial populations.The promotion of phosphate mineral precipitation in order to sequester inorganic contaminants has gained interest in recent years (e.g., [1-5]). Immobilization of contaminants in situ is an attractive option at many sites because the vast quantities of affected media, often with low pollutant concentrations, make excavation or extraction of the contamination infeasible. Phosphate minerals are advantageous for use in sequestration because they are poorly soluble in m
Phylogenetic diversification patterns and divergence times in ground beetles (Coleoptera: Carabidae: Harpalinae)
Karen A Ober, Thomas N Heider
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-262
Abstract: According to molecular divergence date estimates, harpalines originated in the mid Cretaceous but did not diversify extensively until the late Cretaceous or early Paleogene about 32 million years after their origin. In a relatively small window of time, harpalines underwent rapid speciation. Harpalines have a relative high net diversification rate and increased cladogenesis in some regions of the clade. We did not see a significant decrease in diversification rate through time in the MCCR test, but a model of diversification with two shift points to lower diversification rates fit the harpaline lineage accumulation through time the best.Our results indicate harpalines are significantly more diverse and have higher diversification than their sistergroup. Instead of an immediate burst of explosive diversification, harpalines may have had a long "fuse" before major lineages diversified during the early Paleogene when other taxa such as mammals, birds, and some flowering plants were also rapidly diversifying.Ever since Darwin, biologists have been interested in using phylogenetic trees to investigate the pattern and tempo of lineage diversification. We see that the branching patterns in phylogenies contain information about the processes of speciation and extinction. Molecular phylogenies of species rich groups supply hypotheses of evolutionary relationships among higher taxa, and also allow us to test hypotheses about the tempo and pattern of diversification [1-4], revealing both the topology of ancestor-descendant relationships and the tempo of descent among members of a clade. It is clear that organismal diversification rates (speciation minus extinction) have been variable across lineages and through time, with some lineages showing slowing rates of lineage accumulation [5] and others showing rapid diversification [6] or radiations. Radiations are generally defined in a way that includes rapid cladogenesis from a common ancestor [7], yielding taxon rich clades. The
The Effect of Clutch Size and Ant Attendance on Egg Guarding by Entylia Bactriana (Homoptera: Membracidae)
Karen L. Olmstead,Thomas K. Wood
Psyche , 1990, DOI: 10.1155/1990/40278
Abstract:
Page 1 /35849
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.