Effect of expansive optic flow and lateral motion parallax on depth estimation with normal and artificially reduced acuity.

When an observer moves in space, the retinal projection of a stationary object either expands if the motion is toward the object or shifts horizontally if the motion contains a lateral component. This study examined the impact of expansive optic flow and lateral motion parallax on the accuracy of depth perception for observers with normal or artificially reduced acuity and asked whether any benefit is due to the continuous motion or to the discrete object image displacement. Stationary participants viewed a virtual room on a computer screen.

Estimating lighting direction in scenes with multiple objects.

To recover the reflectance and shape of an object in a scene, the human visual system must account for the properties of the light illuminating the object. Here, we examine the extent to which multiple objects within a scene are utilised to estimate the direction of lighting in a scene. In Experiment 1, we presented participants with rendered scenes that contained 1, 9, or 25 unfamiliar blob-like objects and measured their capacity to discriminate whether a directional light source was left or right of the participants' vantage point.

Evaluating the Visibility of Architectural Features for People with Low Vision -A Quantitative Approach.

Most people with low vision rely on their remaining functional vision for mobility. Our goal is to provide tools to help design architectural spaces in which safe and effective mobility is possible by those with low vision---spaces that we refer to as . We describe an approach that starts with a 3D CAD model of a planned space and produces labeled images indicating whether or not structures that are potential mobility hazards are visible at a particular level of low vision.

Cardiac conduction disturbances in rheumatologic disease: a cross-sectional study.

Background: Cardiovascular abnormalities are common in patients with rheumatologic disorders. Tachy-arrhythmias occur more frequently in these patients than the general population; however, the prevalence of bradyarrhythmias in this group is less clear. This investigation aimed to analyze the incidence and predictors of bradyarrhythmias and conduction disturbances, as well as the presence and influence of cardiologist management, in patients with rheumatologic disorders.

Validating a model of architectural hazard visibility with low-vision observers.

Pedestrians with low vision are at risk of injury when hazards, such as steps and posts, have low visibility. This study aims at validating the software implementation of a computational model that estimates hazard visibility. The model takes as input a photorealistic 3D rendering of an architectural space, and the acuity and contrast sensitivity of a low-vision observer, and outputs estimates of the visibility of hazards in the space.

Determining the clinical significance of computer interpreted electrocardiography conclusions.

Background: Computerized electrocardiogram (EKG) interpretation technology was developed in the mid-20th century, but its use continues to be controversial. This study aims to determine clinical factors which indicate greater odds of clinical significance of an abnormal computerized EKG interpretation.

Methods: The inclusion criteria for this retrospective study were patients who underwent outpatient echocardiography for the indication of an abnormal EKG and had an EKG abnormality diagnosed by the computerized EKG system.

Visual adaptation selective for individual limbs reveals hierarchical human body representation.

The spatial relationships between body parts are a rich source of information for person perception, with even simple pairs of parts providing highly valuable information. Computation of these relationships would benefit from a hierarchical representation, where body parts are represented individually. We hypothesized that the human visual system makes use of such representations.

Surface curvature from kinetic depth can affect lightness.

The light reaching the eye confounds the proportion of light reflected from surfaces in the environment with their illumination. To achieve constancy in perceived surface reflectance (lightness) across variations in illumination, the visual system must infer the relative contribution of reflectance to the incoming luminance signals. Previous studies have shown that contour and stereo cues to surface shape can affect the lightness of sawtooth luminance profiles.

Mechanisms of Lead Failure by Recall Status and Manufacturer: Results From the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS").

Objectives: The aim of this study was to determine the differences in lead failure mechanisms across the major United States implantable defibrillator lead manufacturers (Boston Scientific, Medtronic, and St. Jude Medical), between all non-recalled and recalled leads, and between two recalled lead families (Medtronic Sprint Fidelis and the St. Jude Medical Riata and Riata ST).

Differences in Approaches and Outcomes of Defibrillator Lead Implants Between High-Volume and Low-Volume Operators: Results From the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS").

Objectives: The purpose of this study was to investigate the relationship between operator volume and implantable defibrillator lead failure and patient mortality at a single large implanting center.

Methods: This study analyzed the differences between high-volume and low-volume defibrillator implanters in the Pacemaker and Implantable Defibrillator Lead Survival Study ("PAIDLESS") between February 1, 1996 and December 31, 2011 at NYU Winthrop Hospital. "High-volume" was defined as performing ≥500 implants over the study period, while "low-volume" was defined as performing <500 implants.

The perceptual dimensions of natural dynamic flow.

We measured perceptual judgments of category, material attributes, affordances, and similarity to investigate the perceptual dimensions underlying the visual representation of a broad class of natural dynamic flows (sea waves, smoke, and windblown foliage). The dynamic flows were looped 3-s movies windowed with circular apertures of two sizes to manipulate the level of spatial context. In low levels of spatial context (smaller apertures), human observers' judgments of material attributes and affordances were inaccurate, with estimates biased toward assumptions that the flows resulted from objects that were rigid, "pick-up-able," and not penetrable.

Simulating visibility under reduced acuity and contrast sensitivity.

Architects and lighting designers have difficulty designing spaces that are accessible to those with low vision, since the complex nature of most architectural spaces requires a site-specific analysis of the visibility of mobility hazards and key landmarks needed for navigation. We describe a method that can be utilized in the architectural design process for simulating the effects of reduced acuity and contrast on visibility. The key contribution is the development of a way to parameterize the simulation using standard clinical measures of acuity and contrast sensitivity.

The Number of Recalled Leads is Highly Predictive of Lead Failure: Results From the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS").

Objectives: The purpose of this study was to determine if implantation of multiple recalled defibrillator leads is associated with an increased risk of lead failure.

Background: The authors of the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS") have previously reported a relationship between recalled lead status, lead failure, and patient mortality. This substudy analyzes the relationship in a smaller subset of patients who received more than one recalled lead.

Gender-Related and Age-Related Differences in Implantable Defibrillator Recipients: Results From the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS").

Objectives: The purpose of this study was to investigate the influences of gender and age on defibrillator lead failure and patient mortality.

Background: The specific influences of gender and age on defibrillator lead failure have not previously been investigated.

Methods: This study analyzed the differences in gender and age in relation to defibrillator lead failure and mortality of patients in the Pacemaker and Implantable Defibrillator Leads Survival Study ("PAIDLESS").

Human visual cortical responses to specular and matte motion flows.

Determining the compositional properties of surfaces in the environment is an important visual capacity. One such property is specular reflectance, which encompasses the range from matte to shiny surfaces. Visual estimation of specular reflectance can be informed by characteristic motion profiles; a surface with a specular reflectance that is difficult to determine while static can be confidently disambiguated when set in motion.

Scene coherence can affect the local response to natural images in human V1.

Neurons in primary visual cortex (V1) can be indirectly affected by visual stimulation positioned outside their receptive fields. Although this contextual modulation has been intensely studied, we have little notion of how it manifests with naturalistic stimulation. Here, we investigated how the V1 response to a natural image fragment is affected by spatial context that is consistent or inconsistent with the scene from which it was extracted.

Regions of mid-level human visual cortex sensitive to the global coherence of local image patches.

The global structural arrangement and spatial layout of the visual environment must be derived from the integration of local signals represented in the lower tiers of the visual system. This interaction between the spatially local and global properties of visual stimulation underlies many of our visual capacities, and how this is achieved in the brain is a central question for visual and cognitive neuroscience. Here, we examine the sensitivity of regions of the posterior human brain to the global coordination of spatially displaced naturalistic image patches.

Consequences of polar form coherence for fMRI responses in human visual cortex.

Relevant features in the visual image are often spatially extensive and have complex orientation structure. Our perceptual sensitivity to such spatial form is demonstrated by polar Glass patterns, in which an array of randomly-positioned dot pairs that are each aligned with a particular polar displacement (rotation, for example) yield a salient impression of spatial structure. Such patterns are typically considered to be processed in two main stages: local spatial filtering in low-level visual cortex followed by spatial pooling and complex form selectivity in mid-level visual cortex.