scholarly journals Motion tracking of iris features to detect small eye movements

2019 ◽  
Vol 12 (6) ◽  
Author(s):  
Aayush K. Chaudhary ◽  
Jeff B. Pelz
Keyword(s):  
Eye Movements ◽  
Motion Tracking ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
High Confidence ◽  
Corneal Reflection ◽  
Detection Algorithms ◽  
Pupil Center ◽  
Detailed Record ◽  
Very High

The inability of current video-based eye trackers to reliably detect very small eye movements has led to confusion about the prevalence or even the existence of monocular microsaccades (small, rapid eye movements that occur in only one eye at a time). As current methods often rely on precisely localizing the pupil and/or corneal reflection on successive frames, current microsaccade-detection algorithms often suffer from signal artifacts and a low signal-to-noise ratio. We describe a new video-based eye tracking methodology which can reliably detect small eye movements over 0.2 degrees (12 arcmin) with very high confidence. Our method tracks the motion of iris features to estimate velocity rather than position, yielding a better record of microsaccades. We provide a more robust, detailed record of miniature eye movements by relying on more stable, higher-order features (such as local features of iris texture) instead of lower-order features (such as pupil center and corneal reflection), which are sensitive to noise and drift.

scholarly journals Signal-to-Noise Ratio and Astronomical Fourier Transform Spectroscopy

1988 ◽  
Vol 132 ◽  
pp. 71-78
Author(s):  
J. P. Maillard
Keyword(s):  
Fourier Transform ◽  
Signal To Noise Ratio ◽  
Resolving Power ◽  
High Resolution Spectroscopy ◽  
Signal To Noise ◽  
Array Detectors ◽  
Noise Ratio ◽  
The Fourier Transform ◽  
Large Telescopes ◽  
Very High

The multiplex properties of the Fourier Transform Spectrometer (FTS) can be considered as disadvantageous with modern detectors and large telescopes, the dominant noise source being no longer in most applications the detector noise. Nevertheless, a FTS offers a gain in information and other instrumental features remain: flexibility in choosing resolving power up to very high values, large throughput, essential in high–resolution spectroscopy with large telescopes, metrologic accuracy, automatic substraction of parasitic background. The signal–to–noise ratio in spectra can also be improved: by limiting the bandwidth with cold filters or even cold dispersers, by matching the instrument to low background foreoptics and high–image quality telescopes. The association with array detectors provides the solution for the FTS to regain its full multiplex advantage.

Anti-Vibration Sub Allows A Very High Signal-To-Noise Ratio And Improves Borehole Quality

2013 ◽  
Author(s):  
Paul Christian Bates ◽  
Chakib Bouziane ◽  
Denise Nicholl ◽  
Reina Teelken ◽  
Mohammed Zuki Bin Bidi ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
High Signal ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Very High

ENHANCING THE YIELD OF HIGH-DENSITY ELECTRODE ARRAYS THROUGH AUTOMATED ELECTRODE SELECTION

2012 ◽  
Vol 22 (01) ◽  
pp. 1-19 ◽  
Author(s):  
GERT VAN DIJCK ◽  
KARSTEN SEIDL ◽  
OLIVER PAUL ◽  
PATRICK RUTHER ◽  
MARC M. VAN HULLE ◽  
...  
Keyword(s):  
Control Algorithm ◽  
Signal To Noise Ratio ◽  
Pyramidal Cells ◽  
Inhibitory Interneurons ◽  
Electrode Arrays ◽  
Signal To Noise ◽  
Detection Algorithms ◽  
Benchmark Data ◽  
Depth Control ◽  
Electrode Selection

Recently developed CMOS-based microprobes contain hundreds of electrodes on a single shaft with inter-electrode distances as small as 30 μm. So far, neuroscientists needed to select electrodes manually from hundreds of electrodes. Here we present an electronic depth control algorithm that allows to select electrodes automatically, hereby allowing to reduce the amount of data and locating those electrodes that are close to neurons. The electrodes are selected according to a new penalized signal-to-noise ratio (PSNR) criterion that demotes electrodes from becoming selected if their signals are redundant with previously selected electrodes. It is shown that, using the PSNR, interneurons generating smaller spikes are also selected. We developed a model that aims to evaluate algorithms for electronic depth control, but also generates benchmark data for testing spike sorting and spike detection algorithms. The model comprises a realistic tufted pyramidal cell, non-tufted pyramidal cells and inhibitory interneurons. All neurons are synaptically activated by hundreds of fibers. This arrangement allows the algorithms to be tested in more realistic conditions, including backgrounds of synaptic potentials, varying spike rates with bursting and spike amplitude attenuation.

The Accuracy of Saccadic and Perceptual Decisions in Visual Search

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 133-133
Author(s):  
M P Eckstein ◽  
B B Beutter ◽  
L S Stone
Keyword(s):  
Eye Movements ◽  
Spatial Information ◽  
Target Location ◽  
Signal To Noise Ratio ◽  
Saccadic Eye Movements ◽  
Noise Signal ◽  
Signal To Noise ◽  
Viewing Condition ◽  
Perceptual Performance ◽  
Noise Ratio

Saccadic eye movements during search for a target embedded in noise are suboptimally guided by information about target location (Eckstein et al, 1997, paper presented at ARVO). Our goal was to compare the spatial information used to guide the saccades with that used for the perceptual decision. Three observers were asked to determine the location of a bright disk (diameter 21 min arc) in white noise (signal-to-noise ratio 4.2) from among ten possible locations evenly spaced at 5.9 deg eccentricity. In the first of four conditions, observers used natural eye movements. In the three remaining conditions, observers fixated a central cross at all times. The fixation conditions consisted of three different presentation times (100, 200, 300 ms), each followed by a mask. Eye-position data were collected with a resolution of ∼0.2 deg. In the natural viewing condition, we measured the accuracy with respect to the target and the latency of the first saccade. In the fixation conditions, we discarded trials in which observers broke fixation. Perceptual performance was computed for all conditions. Averaged across observers, the first saccade was correct (closest to the target location) for 56±7 (SD) % of trials (chance 10%) and occurred after a latency of 313±56 ms. Perceptual performance averaged 53±4%, 63±4%, 65±2% correct at 100, 200, and 300 ms, respectively. We conclude that, for the signal-to-noise ratio used, at the time of initiation of the first saccade there is little difference between the amount of information about target location available to the perceptual and saccadic systems.

Investigation of copt and copt + ZrOx thin films for magnetic storage media using high-resolution analytical electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 578-579
Author(s):  
R. A. Ristau ◽  
K. Barmak
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Grain Size ◽  
Signal To Noise Ratio ◽  
High Coercivity ◽  
Magnetic Storage ◽  
Signal To Noise ◽  
Storage Media ◽  
Magnetic Storage Media ◽  
Very High

Materials for very high density magnetic storage media, with capacities of 10 Gbits/in2 and beyond, require high coercivity and high signal to noise ratio. To achieve storage densities of this level engineering of the material to produce very fine, magnetically decoupled domains is necessary. We have characterized the microstructure and microchemistry of 10 nm thick CoPt and CoPt + ZrOx thin films, as deposited and annealed, using transmission electron microscopy (TEM) and nanometer-scale energy dispersive x-ray spectroscopy (EDS).CoPt has a very high coercivity (Hc) when annealed to produce the ordered Ll0 phase. Annealing also increases grain size which reduces the signal to noise ratio. Co-sputtering CoPt with ZrOx was intended to reduce grain size. TEM micrographs in Figure 1 show that grain growth was dramatically reduced in the CoPt + ZrOx films. Essential to the development of optimum material properties are quantified grain size measurements, yet owing to the small grain size and the complexity of TEM images due to diffraction contrast there are few systematic studies of grain size in thin films.

Proposal for a Laue lens with quasi-mosaic crystalline tiles

2011 ◽  
Vol 44 (6) ◽  
pp. 1255-1258 ◽  
Author(s):  
Vincenzo Guidi ◽  
Valerio Bellucci ◽  
Riccardo Camattari ◽  
Ilaria Neri
Keyword(s):  
High Resolution ◽  
Crystal Size ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Laue Lens ◽  
Crystalline Anisotropy ◽  
Order Of Magnitude ◽  
Mosaic Crystals ◽  
Noise Ratio ◽  
Very High

Quasi-mosaicity is an effect of secondary bending within a crystal driven by crystalline anisotropy. This effect can be used to fabricate a series of curved crystals for the realization of a Laue lens. It is highlighted that crystals bent by the quasi-mosaic effect allow very high resolution focusing with respect to mosaic crystals. Under the same conditions for energy passband, crystal size and flux of incident photons, a Laue lens based on quasi-mosaic crystals would increase the signal-to-noise ratio by about an order of magnitude compared to the same lens with mosaic crystals. Moreover, no mosaic defocusing occurs for quasi-mosaic crystals.

NQR Studies of Atomic Arrangements and Chemical Bonding in Glasses

1990 ◽  
Vol 45 (3-4) ◽  
pp. 268-272 ◽  
Author(s):  
Donghoon Lee ◽  
S. J. Gravina ◽  
P. J. Bray
Keyword(s):  
Chemical Bonding ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Signal To Noise ◽  
Low Frequencies ◽  
Large N ◽  
Noise Ratio ◽  
Very High

Abstract A very high sensitivity continuous wave NQR spectrometer was developed to detect pure NQR transitions at low frequencies (down to 200 kHz). A signal-to-noise ratio of more than 100 to 1 has been achieved at about 1.36 MHz for crystalline B 2 0 3 . Two large n B responses have been found in vitreous B 2 0 3 (NMR detected only one site) with linewidths of less than 30 kHz. 27 A1 NQR spectra were obtained for OC-A1203 (Corundum), the mineral andalusite (a form of A1203 • Si0 2), and a glass having the composition of anorthite (CaO • A1203 • 2Si0 2).

scholarly journals Direct phasing of nanocrystal diffraction

2013 ◽  
Vol 69 (6) ◽  
pp. 559-569 ◽  
Author(s):  
Veit Elser
Keyword(s):  
High Resolution ◽  
Free Electron ◽  
Free Electron Laser ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
High Resolution Data ◽  
X Ray ◽  
Particle Intensity ◽  
Very High ◽  
Resolution Data

Recent experiments at free-electron laser X-ray sources have been able to resolve the intensity distributions about Bragg peaks in nanocrystals of large biomolecules. Information derived from small shifts in the peak positions augment the Bragg samples of the particle intensity with samples of its gradients. Working on the assumption that the nanocrystal is entirely generated by lattice translations of a particle, an algorithm is developed that reconstructs the particle from intensities and intensity gradients. Unlike traditional direct phasing methods that require very high resolution data in order to exploit sparsity of the electron density, this method imposes no constraints on the contrast other than positivity and works well at low resolution. Successful reconstructions are demonstrated with simulatedP1 lysozyme nanocrystal data down to a signal-to-noise ratio of 2 in the intensity gradients.

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