138 research outputs found

    Looking Beyond the Canonical Formulation and Evaluation Paradigm of Prepositional Phrase Attachment

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    Prepositional phrase attachment has long been considered one of the most difficult tasks in automated syntactic parsing of natural language text. In this thesis, we examine several aspects of what has become the dominant view of PP attachment in natural language processing with an eye toward extending this view to a more realistic account of the problem. In particular, we take issue with the manner in which most PP attachment work is evaluated, and the degree to which traditional assumptions and simplifications no longer allow for realistically meaningful assessments. We also argue for looking beyond the canonical subset of attachment problems, where almost all attention has been focused, toward a fuller view of the task, both in terms of the types of ambiguities addressed and the contextual information considered

    Documentation of Intraretinal Retinal Pigment Epithelium Migration via High-Speed Ultrahigh-Resolution Optical Coherence Tomography

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    Purpose To describe the features of intraretinal retinal pigment epithelium (RPE) migration documented on a prototype spectral-domain, high-speed, ultrahigh-resolution optical coherence tomography (OCT) device in a group of patients with early to intermediate dry age-related macular degeneration (AMD) and to correlate intraretinal RPE migration on OCT to RPE pigment clumping on fundus photographs. Design Retrospective, noncomparative, noninterventional case series. Participants Fifty-five eyes of 44 patients seen at the New England Eye Center between December 2007 and June 2008 with early to intermediate dry AMD. Methods Three-dimensional OCT scan sets from all patients were analyzed for the presence of intraretinal RPE migration, defined as small discreet hyperreflective and highly backscattering lesions within the neurosensory retina. Fundus photographs also were analyzed to determine the presence of RPE pigment clumping, defined as black, often spiculated, areas of pigment clumping within the macula. The en face OCT images were correlated with fundus photographs to demonstrate correspondence of intraretinal RPE migration on OCT and RPE clumping on fundus photography. Main Outcome Measures Drusen, dry AMD, intraretinal RPE migration, and RPE pigment clumping. Results On OCT scans, 54.5% of eyes (61.4% of patients) demonstrated intraretinal RPE migration. Of the fundus photographs, 56.4% demonstrated RPE pigment clumping. All eyes with intraretinal RPE migration on OCT had corresponding RPE pigment clumping on fundus photographs. The RPE pigment migrated most frequently into the outer nuclear layer (66.7% of eyes) and less frequently into more anterior retinal layers. Intraretinal RPE migration mainly occurred above areas of drusen (73.3% of eyes). Conclusions The appearance of intraretinal RPE migration on OCT is a common occurrence in early to intermediate dry AMD, occurring in 54.5% of eyes, or 61.4% of patients. The area of intraretinal RPE migration on OCT always correlated to areas of pigment clumping on fundus photography. Conversely, all but 1 eye with RPE pigment clumping on fundus photography also had areas of intraretinal RPE migration on OCT. The high incidence of intraretinal RPE migration observed above areas of drusen suggests that drusen may play physical and catalytic roles in facilitating intraretinal RPE migration in dry AMD patients.National Institutes of Health (U.S.) (Contract RO1-EY11289-23)National Institutes of Health (U.S.) (Contract R01-EY13178-07)National Institutes of Health (U.S.) (Contract R01-EY013516-07)United States. Air Force Office of Scientific Research (FA9550-07-1-0101)United States. Air Force Office of Scientific Research (FA9550-07-1-0014

    Assessment of Artifacts and Reproducibility across Spectral- and Time-Domain Optical Coherence Tomography Devices

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    Purpose To report the frequency of optical coherence tomography (OCT) scan artifacts and to compare macular thickness measurements, interscan reproducibility, and interdevice agreeability across 3 spectral-domain (SD) OCT (also known as Fourier domain; Cirrus HD-OCT, RTVue-100, and Topcon 3D-OCT 1000) devices and 1 time-domain (TD) OCT (Stratus OCT) device. Design Prospective, noncomparative, noninterventional case series. Participants Fifty-two patients seen at the New England Eye Center, Tufts Medical Center Retina Service, between February and August 2008. Methods Two scans were performed for each of the SD OCT protocols: Cirrus macular cube 512×128 (software version 3.0; Carl Zeiss Meditec, Inc., Dublin, CA), RTVue (E)MM5 and MM6 (software version 3.5; Optovue, Inc., Fremont, CA), Topcon 3D Macular and Radial (software version 2.12; Topcon, Inc., Paramus, NJ), in addition to 1 TD OCT scan via Stratus macular thickness protocol (software version 4.0; Carl Zeiss Meditec, Inc.). Scans were inspected for 6 types of OCT scan artifacts and were analyzed. Interscan reproducibility and interdevice agreeability were assessed by intraclass correlation coefficients (ICCs) and Bland-Altman plots, respectively. Main Outcome Measures Optical coherence tomography image artifacts, macular thickness, reproducibility, and agreeability. Results Time-domain OCT scans contained a significantly higher percentage of clinically significant improper central foveal thickness (IFT) after manual correction (11-μm change or more) compared with SD OCT scans. Cirrus HD-OCT had a significantly lower percentage of clinically significant IFT (11.1%) compared with the other SD OCT devices (Topcon 3D, 20.4%; Topcon Radial, 29.6%; RTVue (E)MM5, 42.6%; RTVue MM6, 24.1%; P = 0.001). All 3 SD OCT devices had central foveal subfield thicknesses that were significantly more than that of TD OCT after manual correction (P<0.0001). All 3 SD OCT devices demonstrated a high degree of reproducibility in the central foveal region (ICCs, 0.92–0.97). Bland-Altman plots showed low agreeability between TD and SD OCT scans. Conclusions Out of all OCT devices analyzed, cirrus HD-OCT scans exhibited the lowest occurrence of any artifacts (68.5%), IFT (40.7%), and clinically significant IFT (11.1%), whereas Stratus OCT scans exhibited the highest occurrence of clinically significant IFT. Further work on improving segmentation algorithm to decrease artifacts is warranted.Research to Prevent Blindness, Inc. (United States) (Challenge Grant)National Institutes of Health (U.S.) (Grant R01-EY11289-23)National Institutes of Health (U.S.) (Grant R01-EY13178-07)National Institutes of Health (U.S.) (Grant P30-EY008098)United States. Air Force Office of Scientific Research (Grant FA9550-07-1-0101)United States. Air Force Office of Scientific Research (Grant FA9550-07-1-0014

    Trabecular Meshwork Engineering and Live Tracking in Perfused Porcine Anterior Segments

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    Purpose: To establish a trabecular meshwork ™ engineering model using porcine anterior segments of consistently high quality in a physiological, fixed perfusion system.\ud \ud Discussion: Compared to previously used human donor eyes, this inexpensive porcine anterior segment perfusion model is of sufficient, repeatable high quality to develop strategies to modify genetically, ablate and repopulate the TM. Despite significant anatomic differences, effects of transduction and ablation in the porcine model presented here replicate key aspects of previously explored human, feline and rodent models

    Propensity to consent to data linkage: experimental evidence on the role of three survey design features in a UK longitudinal panel

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    When performing data linkage, survey respondents need to provide their informed consent. Since not all respondents agree to this request, the linked data-set will have fewer observations than the survey data-set alone and bias may be introduced. By focusing on the role that survey design features play in gaining respondents’ consent, this paper provides an innovative contribution to the studies in this field. Analysing experimental data collected in a nationally representative household panel survey of the British population, we find that interview features such as question format (dependent/independent questions) and placement of the consent question within the questionnaire have an impact on consent rates

    Healthcare, the Environment and Biomedicine

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    The final SSIR project aim: To better understand the factors that impact student well-being at the University of Richmond, with a focus on those that raise happiness and reduce stress.Goals and questions included: ● To find statistically significant data that correlates to who the happiest spidURs are ● Tried to separate student groups to identify individual factors ● Sought out students who had lowest stress, highest happinesshttps://scholarship.richmond.edu/ssir-presentations-2019/1000/thumbnail.jp

    Substrate interaction defects in histidylâ tRNA synthetase linked to dominant axonal peripheral neuropathy

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    Histidylâ tRNA synthetase (HARS) ligates histidine to cognate tRNA molecules, which is required for protein translation. Mutations in HARS cause the dominant axonal peripheral neuropathy Charcotâ Marieâ Tooth disease type 2W (CMT2W); however, the precise molecular mechanism remains undefined. Here, we investigated three HARS missense mutations associated with CMT2W (p.Tyr330Cys, p.Ser356Asn, and p.Val155Gly). The three mutations localize to the HARS catalytic domain and failed to complement deletion of the yeast ortholog (HTS1). Enzyme kinetics, differential scanning fluorimetry (DSF), and analytical ultracentrifugation (AUC) were employed to assess the effect of these substitutions on primary aminoacylation function and overall dimeric structure. Notably, the p.Tyr330Cys, p.Ser356Asn, and p.Val155Gly HARS substitutions all led to reduced aminoacylation, providing a direct connection between CMT2Wâ linked HARS mutations and loss of canonical ARS function. While DSF assays revealed that only one of the variants (p.Val155Gly) was less thermally stable relative to wildâ type, all three HARS mutants formed stable dimers, as measured by AUC. Our work represents the first biochemical analysis of CMTâ associated HARS mutations and underscores how loss of the primary aminoacylation function can contribute to disease pathology.Diseaseâ causing variants in multiple aminoacylâ tRNA synthetase genes have been linked to the dominant inherited peripheral neuropathy Charcot Marie Tooth (CMT) disease. Here, we employed yeast complementation, enzyme kinetics, differential scanning fluorimetry (DSF), and analytical ultra centrifugation (AUC) to investigate three histidylâ tRNA synthetase (HARS) missense mutations associated with CMT2W (p.Tyr330Cys, p.Ser356Asn, and p.Val155Gly). The mutant substitutions all led to reduced catalytic activity and poorer histidine and ATP binding, illustrating how loss of primary aminoacylation function can contribute to disease pathology.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142441/1/humu23380_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142441/2/humu23380.pd

    Reproducibility of in-vivo OCT measured three-dimensional human lamina cribrosa microarchitecture

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    Purpose: To determine the reproducibility of automated segmentation of the three-dimensional (3D) lamina cribrosa (LC) microarchitecture scanned in-vivo using optical coherence tomography (OCT). Methods: Thirty-nine eyes (8 healthy, 19 glaucoma suspects and 12 glaucoma) from 49 subjects were scanned twice using swept-source (SS-) OCT in a 3.5x3.5x3.64 mm (400x400x896 pixels) volume centered on the optic nerve head, with the focus readjusted after each scan. The LC was automatically segmented and analyzed for microarchitectural parameters, including pore diameter, pore diameter standard deviation (SD), pore aspect ratio, pore area, beam thickness, beam thickness SD, and beam thickness to pore diameter ratio. Reproducibility of the parameters was assessed by computing the imprecision of the parameters between the scans. Results: The automated segmentation demonstrated excellent reproducibility. All LC microarchitecture parameters had an imprecision of less or equal to 4.2%. There was little variability in imprecision with respect to diagnostic category, although the method tends to show higher imprecision amongst healthy subjects. Conclusion: The proposed automated segmentation of the LC demonstrated high reproducibility for 3D LC parameters. This segmentation analysis tool will be useful for in-vivo studies of the LC. © 2014 Wang et al
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