625 research outputs found
Is the âVisual Fields Easyâ Application a Useful Tool to Identify Visual Field Defects in Patients Who Have Suffered a Stroke?
Aims: To determine the level of agreement between the visual Fields easy application (VFE) for
iPad and a standard clinical test for assessing peripheral vision in stroke survivors.
Study Design: This was a prospective cross-sectional study comparing the VFE application to the
Humphrey Field Analyser (HFA) SITA Fast c30-2 program in identifying and diagnosing visual field
defects post-stroke.
Place and Duration of Study: The ophthalmic department at Imperial College Healthcare NHS
Trust. Data collection was undertaken between January 2016 and August 2016.
Methodology: A total of 50 participants with a diagnosis of stroke and a suspected visual problem
were recruited to the study. Normative data was collected from 50 participants with no history of
stroke or visual loss. Analysis comprised of comparing the extent of the visual field loss detected by
both the VFE and HFA, and clinically assessing the results for normality.
Results: Bland-Altman analysis demonstrated that with more severe visual field loss, the agreement
between both modalities was found to decrease. There was a higher proportion of false negatives with the VFE compared to the HVF. The bias towards detecting more missed test locations with the
VFE application compared to the HFA was 6% for the normal participants and 2% for the stroke
participants. The limits of agreement between the two modalities were large; 20% and 40% for the
normal and stroke participants respectively. The sensitivity of the VFE application to determine an
abnormal visual field in comparison to HFA was 88% and specificity was 76% in the stroke cohort
based upon a clinical impression of its findings. The majority of stroke participants (88%) found the
VFE test more comfortable to perform.
Conclusion: As a screening tool, the VFE application is quick and easy to administer, preferred by
patients and has good sensitivity and specificity for detecting the presence of an abnormal visual
field when compared to HFA. In patients with extensive visual field loss, the VFE may overestimate
visual field reduction
Designing mixed metal halide ammines for ammonia storage using density functional theory and genetic algorithms
New superior ammonia storage materials are suggested from computational screening. Global optimum of 27â000 mixtures identified testing only âź1.5% of the candidates, proving the success of the genetic algorithm.</p
Simulation of oscillopsia in virtual reality
Purpose: Nystagmus is characterised by involuntary eye movement. A proportion of those with nystagmus experience the world constantly in motion as their eyes move: a symptom known as oscillopsia. Individuals with oscillopsia can be incapacitated and often feel neglected due to limited treatment options. Effective communication of the condition is challenging and no tools to aid communication exist. This paper describes a virtual reality (VR) application that recreates the effects of oscillopsia, enabling others to appreciate the condition.
Methods: Eye tracking data was incorporated into a VR oscillopsia simulator and released as a smartphone app â âNystagmus Oscillopsia Sim VRâ. When a smartphone is used in conjunction with a Google Cardboard headset, it presents an erratic image consistent with oscillopsia. The oscillopsia simulation was appraised by six participants for its representativeness. These individuals have nystagmus and had previously experienced oscillopsia but were not currently symptomatic; they were therefore uniquely placed to judge the app. The participants filled in a questionnaire to record impressions and the usefulness of the app.
Results: The published app has been downloaded ~3700 times (28/02/2018) and received positive feedback from the nystagmus community. The validation study questionnaire scored the accuracy of the simulation an average of 7.8/10 while its ability to aid communication received 9.2/10.
Conclusion: The evidence indicates that the simulation can effectively recreate the sensation of oscillopsia and facilitate effective communication of the symptoms associated with the condition. This has implications for communication of other visual conditions
Approximate Well-supported Nash Equilibria below Two-thirds
In an epsilon-Nash equilibrium, a player can gain at most epsilon by changing
his behaviour. Recent work has addressed the question of how best to compute
epsilon-Nash equilibria, and for what values of epsilon a polynomial-time
algorithm exists. An epsilon-well-supported Nash equilibrium (epsilon-WSNE) has
the additional requirement that any strategy that is used with non-zero
probability by a player must have payoff at most epsilon less than the best
response. A recent algorithm of Kontogiannis and Spirakis shows how to compute
a 2/3-WSNE in polynomial time, for bimatrix games. Here we introduce a new
technique that leads to an improvement to the worst-case approximation
guarantee
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