1,965 research outputs found

    Dysflective cones: Visual function and cone reflectivity in long-term follow-up of acute bilateral foveolitis.

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    PURPOSE:Confocal adaptive optics scanning laser ophthalmoscope (AOSLO) images provide a sensitive measure of cone structure. However, the relationship between structural findings of diminished cone reflectivity and visual function is unclear. We used fundus-referenced testing to evaluate visual function in regions of apparent cone loss identified using confocal AOSLO images. METHODS:A patient diagnosed with acute bilateral foveolitis had spectral-domain optical coherence tomography (SD-OCT) (Spectralis HRA + OCT system [Heidelberg Engineering, Vista, CA, USA]) images indicating focal loss of the inner segment-outer segment junction band with an intact, but hyper-reflective, external limiting membrane. Five years after symptom onset, visual acuity had improved from 20/80 to 20/25, but the retinal appearance remained unchanged compared to 3 months after symptoms began. We performed structural assessments using SD-OCT, directional OCT (non-standard use of a prototype on loan from Carl Zeiss Meditec) and AOSLO (custom-built system). We also administered fundus-referenced functional tests in the region of apparent cone loss, including analysis of preferred retinal locus (PRL), AOSLO acuity, and microperimetry with tracking SLO (TSLO) (prototype system). To determine AOSLO-corrected visual acuity, the scanning laser was modulated with a tumbling E consistent with 20/30 visual acuity. Visual sensitivity was assessed in and around the lesion using TSLO microperimetry. Complete eye examination, including standard measures of best-corrected visual acuity, visual field tests, color fundus photos, and fundus auto-fluorescence were also performed. RESULTS:Despite a lack of visible cone profiles in the foveal lesion, fundus-referenced vision testing demonstrated visual function within the lesion consistent with cone function. The PRL was within the lesion of apparent cone loss at the fovea. AOSLO visual acuity tests were abnormal, but measurable: for trials in which the stimulus remained completely within the lesion, the subject got 48% correct, compared to 78% correct when the stimulus was outside the lesion. TSLO microperimetry revealed reduced, but detectible, sensitivity thresholds within the lesion. CONCLUSIONS AND IMPORTANCE:Fundus-referenced visual testing proved useful to identify functional cones despite apparent photoreceptor loss identified using AOSLO and SD-OCT. While AOSLO and SD-OCT appear to be sensitive for the detection of abnormal or absent photoreceptors, changes in photoreceptors that are identified with these imaging tools do not correlate completely with visual function in every patient. Fundus-referenced vision testing is a useful tool to indicate the presence of cones that may be amenable to recovery or response to experimental therapies despite not being visible on confocal AOSLO or SD-OCT images

    What asteroseismology can do for exoplanets

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    We describe three useful applications of asteroseismology in the context of exoplanet science: (1) the detailed characterisation of exoplanet host stars; (2) the measurement of stellar inclinations; and (3) the determination of orbital eccentricity from transit duration making use of asteroseismic stellar densities. We do so using the example system Kepler-410 (Van Eylen et al. 2014). This is one of the brightest (V = 9.4) Kepler exoplanet host stars, containing a small (2.8 Rearth) transiting planet in a long orbit (17.8 days), and one or more additional non-transiting planets as indicated by transit timing variations. The validation of Kepler-410 (KOI-42) was complicated due to the presence of a companion star, and the planetary nature of the system was confirmed after analyzing a Spitzer transit observation as well as ground-based follow-up observations.Comment: 4 pages, Proceedings of the CoRoT Symposium 3 / Kepler KASC-7 joint meeting, Toulouse, 7-11 July 2014. To be published by EPJ Web of Conference

    Clinical classification of symptomatic heterotopic pancreas of the stomach and duodenum: A case series and systematic literature review

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    BACKGROUND: Heterotopic pancreas (HP) is an aberrant anatomic malformation that occurs most commonly in the upper gastrointestinal tract. While the majority of heterotopic pancreatic lesions are asymptomatic, many manifest severe clinical symptoms which require surgical or endoscopic intervention. Understanding of the clinical manifestations and symptoms of HP is limited due to the lack of large volume studies in the literature. The purpose of this study is to review symptomatic cases at a single center and compare these to a systematic review of the literature in order to characterize common clinical manifestations and treatment of this disease. AIM: To classify the common clinical manifestations of heterotopic pancreas. METHODS: A retrospective review was conducted of pathologic samples containing heterotopic pancreas from 2000-2018. Review was limited to HP of the upper gastrointestinal tract due to the frequency of presentation in this location. Symptomatic patients were identified from review of the medical records and clinical symptoms were tabulated. These were compared to a systematic review of the literature utilizing PubMed and Embase searches for papers pertaining to heterotopic pancreas. Publications describing symptomatic presentation of HP were selected for review. Information including demographics, symptoms, presentation and treatment were compiled and analyzed. RESULTS: Twenty-nine patient were identified with HP at a single center, with six of these identified has having clinical symptoms. Clinical manifestations included, gastrointestinal bleeding, gastric ulceration with/without perforation, pancreatitis, and gastric outlet obstruction. Systemic review of the literature yielded 232 publications detailing symptomatic cases with only 20 studies describing ten or more patients. Single and multi-patient studies were combined to form a cohort of 934 symptomatic patients. The majority of patients presented with abdominal pain (67%) combined with one of the following clinical categories: (1) Dyspepsia, (n = 445, 48%); (2) Pancreatitis (n = 260, 28%); (3) Gastrointestinal bleeding (n = 80, 9%); and (4) Gastric outlet obstruction (n = 80, 9%). The majority of cases (n = 832, 90%) underwent surgical or endoscopic resection with 85% reporting resolution or improvement in their symptoms. CONCLUSION: Heterotopic pancreas can cause significant clinical symptoms in the upper gastrointestinal tract. Better understanding and classification of this disease may result in more accurate identification and treatment of this malformation

    Managing human activity and marine mammals: A biologically based, relativistic risk assessment framework

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    Presented here is a broadly applicable, transparent, repeatable analytical framework for assessing relative risk of anthropogenic disturbances on marine vertebrates, with the emphasis on the sound generating aspects of the activity. The objectives are to provide managers and action-proponents tools with which to objectively evaluate drivers of potential biological risk, to identify data gaps that limit assessment, and to identify actionable measures to reduce risk. Current regulatory assessments of how human activities (particularly those that produce sound) influence the likelihood of marine mammal behavioral responses and potential injury, rely principally on generalized characterizations of exposure and effect using simple, threshold-based criteria. While this is relatively straightforward in regulatory applications, this approach fails to adequately address realistic site and seasonal scenarios, other potential stressors, and scalable outcome probabilities. The risk assessment presented here is primarily based on a common and broad understanding of the spatial-temporal-spectral intersections of animals and anthropogenic activities, and specific examples of its application to hypothetical offshore wind farms are given. The resulting species- and activity-specific framework parses risk into two discrete factors: a population’s innate ‘vulnerability’ (potential degree of susceptibility to disturbance) and an ‘exposure index’ (magnitude-duration severity resulting from exposure to an activity). The classic intersection of these factors and their multi-dimensional components provides a relativistic risk assessment process for realistic evaluation of specified activity contexts, sites, and schedules, convolved with species-specific seasonal presence, behavioral-ecological context, and natural history. This process is inherently scalable, allowing a relativistic means of assessing potential disturbance scenarios, tunable to animal distribution, region, context, and degrees of spatial-temporal-spectral resolution

    Satellite communications systems and technology. Executive Summary

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    NASA and the National Science Foundation (NSF) commissioned a panel of US experts to study the international status of satellite communications systems and technology. The study covers emerging systems concepts, applications, services, and the attendant technologies. The panel members travelled to Europe, Japan, and Russia to gather information first-hand. They visited 17 sites in Europe, 20 sites in Japan, and four in Russia. These included major manufacturers, government organizations, service providers, and associated R&D facilities. The panel's report was reviewed by the sites visited, by the panel, and by representatives of US industry. The report details the information collected and compares it to US activities

    Information and communication technology

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    NASA and the National Science Foundation (NSF) commissioned a panel of U.S. experts to study the international status of satellite communications systems and technology. The study covers emerging systems concepts, applications, services, and the attendant technologies. The panel members traveled to Europe, Japan, and Russia to gather information firsthand. They visited 17 sites in Europe, 20 in Japan, and 4 in Russia. These included major manufacturers, government organizations, service providers, and associated research and development facilities. The panel's report was reviewed by the sites visited, by the panel, and by representatives of U.S. industry. The report details the information collected and compares it to U.S. activities
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