1,256 research outputs found

    Near-bottom seismic profiling: High lateral variability, anomalous amplitudes, and estimates of attenuation

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    For almost a decade the Marine Physical Laboratory of Scripps Institution of Oceanography has been conducting near‐bottom geophysical surveys involving quantitative seismic profiling. Operating initially at 4 kHz and more recently at 6 kHz, this system has provided a wealth of fine scale quantitative data on the acoustic properties of ocean sediments. Over lateral distances of a few meters, 7‐dB changes in overall reflected energy as well as 10‐dB changes from individual reflectors have been observed. Anomalously high amplitudes from deep reflectors have been commonly observed, suggesting that multilayer interference is prevalent in records from such pulsed cw profilers. This conclusion is supported by results from sediment core physical property work and related convolution modeling, as well as by the significant differences observed between 4‐ and 6‐kHz profiles. In general, however, lateral consistency has been adequate in most areas surveyed to permit good estimates of acoustic attenuation from returns from dipping reflectors and sediment wedges

    Association between perceived coercion and perceived level of information in involuntarily admitted patients: Results from a multicenter observational study in Switzerland.

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    Involuntary admissions (IA) to psychiatric hospitals are controversial because they interfere with people's autonomy. In some situations, however, they appear to be unavoidable. Interestingly, not all patients perceive the same degree of coercion during IA. The aim of this study was to assess whether the level of knowledge about one's own IA is associated with perceived coercion. This multicenter observational study was conducted on n = 224 involuntarily admitted patients. Interviews were conducted at five study centers from April 2021 to November 2021. The Macarthur Admission Experience Survey was administered to assess perceived coercion. Knowledge of involuntary admission, perceptions of information received, and attitudes towards legal aspects of involuntary admission were also assessed. We found that higher levels of knowledge about IA were negatively associated with perceived coercion at admission. Perceived coercion did not differ between study sites. Only half of the patients felt well informed about their IA, and about a quarter found the information they received difficult to understand. Legislation in Switzerland requires that patients with IA be informed about the procedure. Strategies to improve patients' understanding of the information given to them about IA might be helpful to reduce perceived coercion, which is known to be associated with negative attitudes towards psychiatry, a disturbed therapeutic relationship, avoidance of psychiatry, and the risk of further coercion

    An intrinsically eye safe approach to high apparent brightness augmented reality displays using digital holography

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    Achieving the luminance of real-world scenes is a challenge for many display technologies when seeking to deliver an experience that approaches the dynamic range of the human eye. Digital holography offers a number of significant advantages in this respect, due both to the high optical efficiency, and the ability to redistribute available luminous flux to individual points as required. This property is especially important when the aim is to present sparse digital elements that need to be clearly perceived against a bright real- world background in an AR or MR application. In this work we show that a configuration capable of delivering apparent display brightness equivalent to that of the daytime sky is achievable with components viable for a consumer head mounted display, and identify the constraints necessary to ensure that such a device would be intrinsically eye safe

    Corneal collagen cross-linking (CXL) for the treatment of melting keratitis in cats and dogs: a pilot study

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    Objective UV-A/riboflavin cross-linking (CXL) of corneal collagen fibers is an established, highly promising therapy for corneal melting in physician-based ophthalmology. A prospective pilot study was conducted to demonstrate proof of principle of this novel method for the treatment of melting corneal ulcers in dogs and cats. Procedures After obtaining owner consent, CXL was performed in three cats and three dogs with corneal melting, which either affected the entire corneal surface or was resistant to conventional antibiotic and anticollagenolytic therapy, or affected parts or all of the corneal surface. Medical therapy was continued in all patients. The available follow-up ranged from 2 to 22.5 months and involved slit-lamp examination, fluorescein staining, and photographic documentation during all rechecks. Results Surgical stabilization of the cornea was not necessary in any case, because progression of corneal melting was arrested in all cases within 1–20 days of CXL treatment. Corneal re-epithelization occurred within 7–40 days in all eyes. At 40 days after CXL, all eyes presented a quiescent corneal state without signs of active inflammation and with beginning scar formation. The complications observed in three of the six animals included a corneal sequestrum, superficial corneal stromal pigmentation, and bullous keratopathy. Conclusions This study shows the feasibility of CXL to treat progressive corneal melting in veterinary patients. CXL may represent a cost-efficient and safe alternative therapy in the treatment for corneal melting in veterinary ophthalmology. More investigations comparing the effectivity and complication rate of CXL to those of standard medical treatment are necessary

    Corneal collagen cross-linking as treatment for infectious and non-infectious corneal melting in cats and dogs: results of a prospective, non-randomized, controlled trial

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    OBJECTIVE. UV-A/Riboflavin crosslinking of corneal collagen fibers (CXL) is a highly promising therapy for corneal melting in humans. A prospective interventional, non-randomized, controlled study was conducted to compare the stabilizing effect of CXL treatment on melting keratitis in dogs and cats and the complication rate of CXL to those of standardized intensive medical treatment. PROCEDURES. Forty-nine eyes with melting keratitis were included in the study between October 2009 and October 2012. All eyes were treated according to the same medical treatment protocol. Nineteen eyes were CXL-treated and 30 eyes were not. Follow-up included slit-lamp examination, fluorescein staining, ulcer size measurement, stromal stability evaluation, photographic documentation and documentation of complications. RESULTS. Five of 19 eyes in the CXL group and 9/30 eyes in the control group required rescue stabilization due to continued melting. Seven of the 9 control group corneas stabilized after rescue CXL treatment. At initial presentation, the ulcers in the canine CXL group were significantly deeper and larger than in the control group. Ulcer deepening during follow-up was more pronounced in the canine control group than in the canine CXL group. CXL treatment related complications were not observed. CONCLUSIONS. Based on the similar failure rates in the control and CXL treatment groups despite the poorer initial situation in the CXL group, the tendency for the ulcers in the control group to deepen and the stabilization of all corneas receiving CXL rescue treatment, we believe that CXL has its place as an adjunctive therapy for melting keratitis in veterinary ophthalmology

    Empirical Survival Jensen-Shannon Divergence as a Goodness-of-Fit Measure for Maximum Likelihood Estimation and Curve Fitting

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    The coefficient of determination, known as R2, is commonly used as a goodness-of-fit criterion for fitting linear models. R2 is somewhat controversial when fitting nonlinear models, although it may be generalised on a case-by-case basis to deal with specific models such as the logistic model. Assume we are fitting a parametric distribution to a data set using, say, the maximum likelihood estimation method. A general approach to measure the goodness-of-fit of the fitted parameters, which is advocated herein, is to use a non- parametric measure for comparison between the empirical distribution, comprising the raw data, and the fitted model. In particular, for this purpose we put forward the Survi- val Jensen-Shannon divergence (SJS) and its empirical counterpart (ESJS) as a metric which is bounded, and is a natural generalisation of the Jensen-Shannon divergence. We demonstrate, via a straightforward procedure making use of the ESJS, that it can be used as part of maximum likelihood estimation or curve fitting as a measure of goodness-of-fit, including the construction of a confidence interval for the fitted parametric distribution. Furthermore, we show the validity of the proposed method with simulated data, and three empirical data sets

    Kantonale Unterschiede bei der Umsetzung der fürsorgerischen Unterbringung in der Schweiz [Cantonal Differences in The Implementation of Involuntary Admission in Switzerland]

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    To examine sociodemographic and clinical characteristics of persons hospitalized in five psychiatric hospitals from regions with different structural characteristics compared with persons hospitalized voluntarily. Descriptive analyses of routine data on approximately 57000 cases of 33000 patients treated for a primary ICD-10 psychiatric diagnosis at one of the participating hospitals from 2016 to 2019. Admission rates, length of stay, rates of further coercive measures, sociodemographic and clinical characteristics of the affected persons differ between the different regions. There are considerable regional differences between regulations and implementation of the admission procedures and the sample. Causal relationships between regional specifics and the results cannot be inferred
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