207 research outputs found
Two subsets of human alphoid repetitive DNA show distinct preferential localization in the pericentromeric heterochromatin of chromosomes 13, 21 and 18
Confocal Blue Reflectance Imaging in Type 2 Idiopathic Macular Telangiectasia
PURPOSE. To report the characteristics of confocal blue reflectance imaging in type 2 idiopathic macular telangiectasia (type 2 IMT). METHODS. In a prospective observational cross-sectional study, both eyes of 33 patients with type 2 IMT were examined by means of fundus biomicroscopy, fundus photography, fluorescein angiography, and optical coherence tomography (OCT). Confocal blue reflectance (CBR) imaging was performed using a confocal scanning laser ophthalmoscope (HRA2; Heidelberg Engineering, Heidelberg, Germany). To compare the results derived from different imaging modalities, an analysis was performed using image analysis software (Heidelberg Eye Explorer; Heidelberg Engineering). RESULTS. CBR imaging revealed a parafoveal area of increased reflectance that was slightly larger than the area of hyperfluorescence in late-phase fluorescein angiography. The area usually encompassed an oval parafoveal area, but sectors could be spared. A parafoveal area of increased CBR was detected in 98% of eyes that showed angiographic evidence for type 2 IMT. CONCLUSIONS. CBR imaging is a new, noninvasive, and sensitive method that may contribute to differentiate type 2 IMT from other diseases. Abnormalities of macular pigment distribution and Miiller cell pathology may contribute to the phenomenon of increased CBR and thus the pathophysiology of type 2 IMT
Impressions of force in visual perception of collision events: A test of the causal asymmetry hypothesis
When two objects interact they exert equal and opposite forces on each other. According to the causal asymmetry hypothesis, however, when one object has been identified as causal and the other as that in which the effect occurs, the causal object is perceived as exerting greater force on the effect object than the latter is perceived as exerting on the former. An example of this is a stimulus in which one object moves toward another stationary one, and when contact occurs the former stops and the latter moves away. In this situation the initially moving object is identified as causal, so the causal asymmetry hypothesis predicts that more force will be judged to be exerted by the moving object on the stationary one than by the stationary one on the moving one. Participants’ judgments consistently supported this hypothesis for a variety of stimuli in which kinematic parameters were varied, even when the initially moving object reversed direction after contact
The relative impact of vision impairment and cardiovascular disease on quality of life: the example of pseudoxanthoma elasticum
<p>Abstract</p> <p>Objective</p> <p>To investigate the impact of pseudoxanthoma elasticum (PXE), a rare hereditary disease of concurrent vision impairment (VI) and cardiovascular complications (CVCs), on vision-related (VRQoL) and health-related quality of life (HRQoL).</p> <p>Methods</p> <p>VRQoL and HRQoL were assessed using the Impact of Vision Impairment (IVI) questionnaire and the Short Form Health Survey (SF-36) in 107 PXE patients. Patients were stratified into four groups: A = no VI or CVC; B = CVCs only; C = VI only; and D = both VI and CVCs.</p> <p>Results</p> <p>Following Rasch analysis, the IVI was found to function as a vision-specific functioning and emotional well-being subscale, and the SF-36 as a health-related physical functioning and mental health subscale. The presence of VI and CVC were significant predictors of vision-specific functioning and emotional well-being (p < 0.001), with a clinically meaningful decrement in vision-specific functioning in patients with VI. No associations were found for the SF-36 Physical Functioning and Mental Health scores between any groups.</p> <p>Conclusions</p> <p>Vision impaired patients with PXE report significantly poorer vision-specific functioning than PXE patients without VI. In contrast, the relative impact of PXE on reported general HRQoL was much less. Our results suggest that vision impairment has the larger impact on QoL in this sample.</p
Feta: Efficient Threshold Designated-Verifier Zero-Knowledge Proofs
Zero-Knowledge protocols have increasingly become both popular and practical in recent years due to their applicability in many areas such as blockchain systems. Unfortunately, public verifiability and small proof sizes of zero-knowledge protocols currently come at the price of strong assumptions, large prover time, or both, when considering statements with millions of gates. In this regime, the most prover-efficient protocols are in the designated verifier setting, where proofs are only valid to a single party that must keep a secret state.
In this work, we bridge this gap between designated-verifier proofs and public verifiability by distributing the verifier.
Here, a set of verifiers can then verify a proof and, if a given threshold of the verifiers is honest and trusted, can act as guarantors for the validity of a statement. We achieve this while keeping the concrete efficiency of current designated-verifier proofs, and present constructions that have small concrete computation and communication cost. We present practical protocols in the setting of threshold verifiers with and , for which we give performance figures, showcasing the efficiency of our approach
Cynomolgus monkey's choroid reference database derived from hybrid deep learning optical coherence tomography segmentation.
Cynomolgus monkeys exhibit human-like features, such as a fovea, so they are often used in non-clinical research. Nevertheless, little is known about the natural variation of the choroidal thickness in relation to origin and sex. A combination of deep learning and a deterministic computer vision algorithm was applied for automatic segmentation of foveolar optical coherence tomography images in cynomolgus monkeys. The main evaluation parameters were choroidal thickness and surface area directed from the deepest point on OCT images within the fovea, marked as the nulla with regard to sex and origin. Reference choroid landmarks were set underneath the nulla and at 500 µm intervals laterally up to a distance of 2000 µm nasally and temporally, complemented by a sub-analysis of the central bouquet of cones. 203 animals contributed 374 eyes for a reference choroid database. The overall average central choroidal thickness was 193 µm with a coefficient of variation of 7.8%, and the overall mean surface area of the central bouquet temporally was 19,335 µm2 and nasally was 19,283 µm2. The choroidal thickness of the fovea appears relatively homogeneous between the sexes and the studied origins. However, considerable natural variation has been observed, which needs to be appreciated
Low-complexity weak pseudorandom functions in AC0[MOD2]
A weak pseudorandom function (WPRF) is a keyed function fk:{0,1}n→{0,1} such that, for a random key k, a collection of samples (x,fk(x)), for uniformly random inputs x, cannot be efficiently distinguished from totally random input-output pairs (x, y). We study WPRFs in AC0[MOD2], the class of functions computable by AC0 circuits with parity gates, making
Volume-rendered optical coherence tomography angiography during ocular interventions: Advocating for noninvasive intraoperative retinal perfusion monitoring.
We aimed to test for feasibility of volume-rendered optical coherence tomography angiography (OCTA) as a novel method for assessing/quantifying retinal vasculature during ocular procedures and to explore the potential for intraoperative use. Thirty patients undergoing periocular anaesthesia were enrolled, since published evidence suggests a reduction in ocular blood flow. Retinal perfusion was monitored based on planar OCTA image-derived data provided by a standard quantification algorithm and postprocessed/volume-rendered OCTA data using a custom software script. Overall, imaging procedures were successful, yet imaging artifacts occurred frequently. In interventional eyes, perfusion parameters decreased during anaesthesia. Planar image-derived and volume rendering-derived parameters were correlated. No correlation was found between perfusion parameters and a motion artifact score developed for this study, yet all perfusion parameters correlated with signal strength as displayed by the device. Concluding, volume-rendered OCTA allows for noninvasive three-dimensional retinal vasculature assessment/quantification in challenging surgical settings and appears generally feasible for intraoperative use
Reading Performance Is Reduced by Parafoveal Scotomas in Patients with Macular Telangiectasia Type 2
PURPOSE. Macular telangiectasia (MacTel) type 2 typically exhibits sharply demarcated parafoveal scotomas. In an investigation of their significance for reading performance, reading acuity and speed were measured and correlated with parafoveal sensitivity and fixation stability. METHODS. In this prospective controlled cross-sectional observational study, 49 eyes of 26 patients with MacTel type 2 were investigated. Twenty-four eyes of 14 age-matched normal subjects served as the control. Reading acuity and reading speed (in words per minute [wpm]) were assessed by Radner charts. Retinal sensitivity was measured using fundus controlled microperimetry (MP1; Nidek Technologies). Fixation stability was quantified by the bivariate contour ellipse area (BCEA). Multiple logistic regression analysis was used to delineate outcome predictors of reading acuity and speed. RESULTS. Mean reading speed was considerably reduced in patients (to 141 wpm; control speed, 190 wpm; P Ͻ 0.001) as was reading acuity (patients, 20/63; control subjects, 20/32; P Ͻ 0.001). Mean best corrected visual acuity (BCVA) was reduced in most eyes (patients, 20/50; control subjects, 20/20; P Ͻ 0.001). Mean BCEA was not reduced compared with that in the control subjects. BCVA reduction predicted reading acuity loss (P ϭ 0.02) and a decrease in maximum reading speed (P Ͻ 0.001). Parafoveal sensitivity loss resulted in decreased reading acuity (P ϭ 0.03) and reading speed reduction (P Ͻ 0.001). CONCLUSIONS. These findings indicate that parafoveal sensitivity loss in MacTel type 2 is associated with loss of reading performance despite stable central fixation. Reading performance appears to be a sensitive variable of functional impairment in MacTel type 2 and should therefore be considered an outcome measure in future interventional trials. (Invest Ophthalmol Vis Sci
High Performance Multi-Party Computation for Binary Circuits Based on Oblivious Transfer
We present a unified view of the two-party and multi-party computation protocols based on oblivious transfer first outlined in Nielsen \emph{et al.} (CRYPTO 2012) and Larraia et al. (CRYPTO 2014). We present a number of modifications and improvements to these earlier presentations, as well as full proofs of the entire protocol. Improvements include a unified pre-processing and online MAC methodology, mechanisms to pass between different MAC variants, and fixing a minor bug in the protocol of Larraia \emph{et al.}~in relation to a selective failure attack. It also fixes a minor bug in Nielsen \emph{et al.} resulting from using Jensen\u27s inequality in the wrong direction in an analysis
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