scholarly journals Fast Periodic Stimulation (FPS): A highly effective approach in fMRI brain mapping

2017 ◽  
Author(s):  
Xiaoqing Gao ◽  
Francesco Gentile ◽  
Bruno Rossion
Keyword(s):  
Brain Mapping ◽  
Signal To Noise Ratio ◽  
Fold Increase ◽  
Signal To Noise ◽  
Retest Reliability ◽  
Low Level ◽  
Periodic Stimulation ◽  
Noise Ratio ◽  
Test Retest Reliability ◽  
Very High

SummaryFunctional magnetic resonance imaging (fMRI) is a major technique for human brain mapping. We present a Fast Periodic Stimulation (FPS) fMRI approach, demonstrating its high effectiveness in defining category-selective brain regions. Observers see a dynamic stream of widely variable natural object images alternating at a fast rate (6 images/sec). Every 9 seconds, a short burst of variable face images contrasting with objects in pairs induces an objective 0.111 Hz face-selective neural response in the ventral occipito-temporal cortex and beyond. A model-free Fourier analysis achieves a two-fold increase in signal-to-noise ratio compared to a conventional block-design approach with identical stimuli. Periodicity of category contrast and random variability among images minimize low-level visual confounds while preserving naturalness of the stimuli, leading to the highest values (80-90%) of test-retest reliability yet reported in this area of research. FPS-fMRI opens a new avenue for understanding brain function with low temporal resolution methods.HighlightsFPS-fMRI achieves a two-fold increase in peak SNR over conventional approachFPS-fMRI reveals comprehensive extended face-selective areas including ATLFPS-fMRI achieves high specificity by minimizing influence of low-level visual cuesFPS-fMRI achieves very high test-retest reliability (80%-90%) in spatial activation mapeTOC BlurbIn BriefGao et al. present a novel FPS-fMRI approach, which achieves a two-fold increase in peak signal-to-noise ratio in defining the neural basis of visual categorization while preserving ecological validity, minimizing low-level visual confounds and reaching very high (80%-90%) test-retest reliability.

scholarly journals Language-Independent Hearing Screening Based on Masked Recognition of Ecological Sounds

2019 ◽  
Vol 23 ◽  
pp. 233121651986656
Author(s):  
Sam Denys ◽  
Jan De Laat ◽  
Wouter Dreschler ◽  
Michael Hofmann ◽  
Astrid van Wieringen ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Signal To Noise Ratio ◽  
Steep Slope ◽  
Reference Curve ◽  
Signal To Noise ◽  
Frequency Spectra ◽  
Retest Reliability ◽  
Sound Reception ◽  
Noise Ratio ◽  
Test Retest Reliability

A language-independent automated self-test on tablet based on masked recognition of ecological sounds, the Sound Ear Check (SEC), was developed. In this test, 24 trials of eight different sounds are randomly presented in a noise that was spectrally shaped according to the average frequency spectra of the stimulus sounds, using a 1-up 2-down adaptive procedure. The test was evaluated in adults with normal hearing and hearing loss, and its feasibility was investigated in young children, who are the target population of this test. Following equalization of perceptual difficulty across sounds by applying level adjustments to the individual tokens, a reference curve with a steep slope of 18%/dB was obtained, resulting in a test with a high test–retest reliability of 1 dB. The SEC sound reception threshold was significantly associated with the averaged pure tone threshold ( r = .70), as well as with the speech reception threshold for the Digit Triplet Test ( r = .79), indicating that the SEC is susceptible to both audibility and signal-to-noise ratio loss. Sensitivity and specificity values on the order of magnitude of ∼70% and ∼80% to detect individuals with mild and moderate hearing loss, respectively, and ∼80% to detect individuals with slight speech-in-noise recognition difficulties were obtained. Homogeneity among sounds was verified in children. Psychometric functions fitted to the data indicated a steep slope of 16%/dB, and test–retest reliability of sound reception threshold estimates was 1.3 dB. A reference value of −9 dB signal-to-noise ratio was obtained. Test duration was around 6 minutes, including training and acclimatization.

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.

scholarly journals An Improved Impact Source Locating System Using FBG Rosette Array

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3453
Author(s):  
Chen ◽  
Shin
Keyword(s):  
Light Source ◽  
Signal To Noise Ratio ◽  
Fold Increase ◽  
Fiber Axis ◽  
Source Spectrum ◽  
Directional Sensitivity ◽  
Signal To Noise ◽  
Location Accuracy ◽  
System Sensitivity ◽  
Noise Ratio

For structures vulnerable to foreign object impact damages, it would be desirable to detect and locate any occurrence of such impacts. This can be achieved by monitoring the stress waves generated by an impact together with certain source localization algorithms. Being small, electromagnetic influence immune and durable, Fiber Bragg grating (FBG) sensors are advantageous for this task. One drawback of FBGs for this purpose is their uneven directional sensitivity, which limits its localization ability to within 50° on either side of the fiber axis. Beyond this range, the signal is too weak and masked by noises and the location errors increase abruptly. Two approaches have been tested on a 0.8 m × 0.8 m × 6 mm plate for possible improvement on the system accuracy: firstly, an interrogation scheme with stronger light source intensity and steeper edge filter is employed to enhance the signal-to-noise ratio and system sensitivity; secondly, rosettes with two orthogonal FBGs are cascaded together to replace single FBGs to alleviate the directional sensitivity problem. It was found that a four-fold increase in signal to noise ratio contributed by stronger light source does improve the location accuracy, but only marginally. For the rosette approach, the relative positions of the Bragg wavelength of the FBGs and the light source spectrum are crucial to accuracy. Three different wavelength configurations have been tested and the reasons for their success or failure are discussed. It was shown that with an optimal wavelength configuration, the rosette array can virtually extend the good location accuracy to all over the plate.

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

Strongly Coupled Data Assimilation Using Leading Averaged Coupled Covariance (LACC). Part II: CGCM Experiments*

2015 ◽  
Vol 143 (11) ◽  
pp. 4645-4659 ◽  
Author(s):  
Feiyu Lu ◽  
Zhengyu Liu ◽  
Shaoqing Zhang ◽  
Yun Liu ◽  
Robert Jacob
Keyword(s):  
Data Assimilation ◽  
General Circulation ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Model Framework ◽  
Strongly Coupled ◽  
Low Level ◽  
Atmosphere Temperature ◽  
Noise Ratio ◽  
Coupled Data Assimilation

Abstract This paper uses a fully coupled general circulation model (CGCM) to study the leading averaged coupled covariance (LACC) method in a strongly coupled data assimilation (SCDA) system. The previous study in a simple coupled climate model has shown that, by calculating the coupled covariance using the leading averaged atmospheric states, the LACC method enhances the signal-to-noise ratio and improves the analysis quality of the slow model component compared to both the traditional weakly coupled data assimilation without cross-component adjustments (WCDA) and the regular SCDA using the simultaneous coupled covariance (SimCC). Here in Part II, the LACC method is tested with a CGCM in a perfect-model framework. By adding the observational adjustments from the low-level atmosphere temperature to the sea surface temperature (SST), the SCDA using LACC significantly reduces the SST error compared to WCDA over the globe; it also improves from the SCDA using SimCC, which performs better than the WCDA only in the deep tropics. The improvement in SST analysis is a result of the enhanced signal-to-noise ratio in the LACC method, especially in the extratropical regions. The improved SST analysis also benefits the subsurface ocean temperature and low-level atmosphere temperature analyses through dynamic and statistical processes.

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.

fMRI brain mapping during motion capture and FES induced motor tasks: Signal to noise ratio assessment

2011 ◽  
Vol 33 (8) ◽  
pp. 1027-1032 ◽  
Author(s):  
Marta Gandolla ◽  
Simona Ferrante ◽  
Claudia Casellato ◽  
Giancarlo Ferrigno ◽  
Franco Molteni ◽  
...  
Keyword(s):  
Motion Capture ◽  
Brain Mapping ◽  
Signal To Noise Ratio ◽  
Motor Tasks ◽  
Signal To Noise ◽  
Noise Ratio

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).

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