The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Simona Buetti - One of the best experts on this subject based on the ideXlab platform.
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correction to a target Contrast Signal theory of parallel processing in goal directed search
Attention Perception & Psychophysics, 2020Co-Authors: Alejandro Lleras, Zhiyuan Wang, Kirk Ballew, Simona BuettiAbstract:During production of the article, Figure 4 was incorrectly used twice in the initial article, so it appeared both as Figure 4 and Figure 5 in the article.
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A target Contrast Signal theory of parallel processing in goal-directed search
Attention Perception & Psychophysics, 2020Co-Authors: Alejandro Lleras, Zhiyuan Wang, Kirk Ballew, Simona BuettiAbstract:Feature Integration Theory (FIT) set out the groundwork for much of the work in visual cognition since its publication. One of the most important legacies of this theory has been the emphasis on feature-specific processing. Nowadays, visual features are thought of as a sort of currency of visual attention (e.g., features can be attended, processing of attended features is enhanced), and attended features are thought to guide attention towards likely targets in a scene. Here we propose an alternative theory – the Target Contrast Signal Theory – based on the idea that when we search for a specific target, it is not the target-specific features that guide our attention towards the target; rather, what determines behavior is the result of an active comparison between the target template in mind and every element present in the scene. This comparison occurs in parallel and is aimed at rejecting from consideration items that peripheral vision can confidently reject as being non-targets. The speed at which each item is evaluated is determined by the overall Contrast between that item and the target template. We present computational simulations to demonstrate the workings of the theory as well as eye-movement data that support core predictions of the theory. The theory is discussed in the context of FIT and other important theories of visual search.
J. Klingelhöfer - One of the best experts on this subject based on the ideXlab platform.
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methodological parameters influence the detection of right to left shunts by Contrast transcranial doppler ultrasonography
Stroke, 1999Co-Authors: J. J. Schwarze, Viken L Babikian, D. Sander, C. Kukla, I. Wittich, J. KlingelhöferAbstract:Background and Purpose—Contrast transcranial Doppler ultrasonography is a new method to detect intracardiac right-to-left shunts, such as the patent foramen ovale. However, the methodology of the procedure varies considerably among investigators. This study was undertaken to assess the influence of methodological parameters on the results of the Contrast transcranial Doppler examination in the detection of right-to-left shunts. Methods—A total of 72 patients (mean age, 58.2±14.7 years) had a Contrast transcranial Doppler ultrasonography examination. To study the influence of methodological factors, patients with evidence of a right-to-left shunt underwent repeated examinations with modified procedures. Parameters under investigation were the timing of the Valsalva maneuver, the dose of the Contrast medium, and the patient’s posture during the examination. Results—The median Contrast Signal count was 58.5 and 48.0 (P<0.001) and the median latency of the first intracranially detected Contrast Signal was 12....
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Methodological Parameters Influence the Detection of Right-to-Left Shunts by Contrast Transcranial Doppler Ultrasonography
Stroke, 1999Co-Authors: J. J. Schwarze, Viken L Babikian, D. Sander, C. Kukla, I. Wittich, J. KlingelhöferAbstract:Background and Purpose—Contrast transcranial Doppler ultrasonography is a new method to detect intracardiac right-to-left shunts, such as the patent foramen ovale. However, the methodology of the procedure varies considerably among investigators. This study was undertaken to assess the influence of methodological parameters on the results of the Contrast transcranial Doppler examination in the detection of right-to-left shunts. Methods—A total of 72 patients (mean age, 58.2±14.7 years) had a Contrast transcranial Doppler ultrasonography examination. To study the influence of methodological factors, patients with evidence of a right-to-left shunt underwent repeated examinations with modified procedures. Parameters under investigation were the timing of the Valsalva maneuver, the dose of the Contrast medium, and the patient’s posture during the examination. Results—The median Contrast Signal count was 58.5 and 48.0 (P
Alejandro Lleras - One of the best experts on this subject based on the ideXlab platform.
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correction to a target Contrast Signal theory of parallel processing in goal directed search
Attention Perception & Psychophysics, 2020Co-Authors: Alejandro Lleras, Zhiyuan Wang, Kirk Ballew, Simona BuettiAbstract:During production of the article, Figure 4 was incorrectly used twice in the initial article, so it appeared both as Figure 4 and Figure 5 in the article.
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A target Contrast Signal theory of parallel processing in goal-directed search
Attention Perception & Psychophysics, 2020Co-Authors: Alejandro Lleras, Zhiyuan Wang, Kirk Ballew, Simona BuettiAbstract:Feature Integration Theory (FIT) set out the groundwork for much of the work in visual cognition since its publication. One of the most important legacies of this theory has been the emphasis on feature-specific processing. Nowadays, visual features are thought of as a sort of currency of visual attention (e.g., features can be attended, processing of attended features is enhanced), and attended features are thought to guide attention towards likely targets in a scene. Here we propose an alternative theory – the Target Contrast Signal Theory – based on the idea that when we search for a specific target, it is not the target-specific features that guide our attention towards the target; rather, what determines behavior is the result of an active comparison between the target template in mind and every element present in the scene. This comparison occurs in parallel and is aimed at rejecting from consideration items that peripheral vision can confidently reject as being non-targets. The speed at which each item is evaluated is determined by the overall Contrast between that item and the target template. We present computational simulations to demonstrate the workings of the theory as well as eye-movement data that support core predictions of the theory. The theory is discussed in the context of FIT and other important theories of visual search.
J. J. Schwarze - One of the best experts on this subject based on the ideXlab platform.
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methodological parameters influence the detection of right to left shunts by Contrast transcranial doppler ultrasonography
Stroke, 1999Co-Authors: J. J. Schwarze, Viken L Babikian, D. Sander, C. Kukla, I. Wittich, J. KlingelhöferAbstract:Background and Purpose—Contrast transcranial Doppler ultrasonography is a new method to detect intracardiac right-to-left shunts, such as the patent foramen ovale. However, the methodology of the procedure varies considerably among investigators. This study was undertaken to assess the influence of methodological parameters on the results of the Contrast transcranial Doppler examination in the detection of right-to-left shunts. Methods—A total of 72 patients (mean age, 58.2±14.7 years) had a Contrast transcranial Doppler ultrasonography examination. To study the influence of methodological factors, patients with evidence of a right-to-left shunt underwent repeated examinations with modified procedures. Parameters under investigation were the timing of the Valsalva maneuver, the dose of the Contrast medium, and the patient’s posture during the examination. Results—The median Contrast Signal count was 58.5 and 48.0 (P<0.001) and the median latency of the first intracranially detected Contrast Signal was 12....
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Methodological Parameters Influence the Detection of Right-to-Left Shunts by Contrast Transcranial Doppler Ultrasonography
Stroke, 1999Co-Authors: J. J. Schwarze, Viken L Babikian, D. Sander, C. Kukla, I. Wittich, J. KlingelhöferAbstract:Background and Purpose—Contrast transcranial Doppler ultrasonography is a new method to detect intracardiac right-to-left shunts, such as the patent foramen ovale. However, the methodology of the procedure varies considerably among investigators. This study was undertaken to assess the influence of methodological parameters on the results of the Contrast transcranial Doppler examination in the detection of right-to-left shunts. Methods—A total of 72 patients (mean age, 58.2±14.7 years) had a Contrast transcranial Doppler ultrasonography examination. To study the influence of methodological factors, patients with evidence of a right-to-left shunt underwent repeated examinations with modified procedures. Parameters under investigation were the timing of the Valsalva maneuver, the dose of the Contrast medium, and the patient’s posture during the examination. Results—The median Contrast Signal count was 58.5 and 48.0 (P
Meng-xing Tang - One of the best experts on this subject based on the ideXlab platform.
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correction of non linear propagation artifact in Contrast enhanced ultrasound imaging of carotid arteries methods and in vitro evaluation
Ultrasound in Medicine and Biology, 2015Co-Authors: Yesna O Yildiz, Robert J. Eckersley, Adrian Lim, David O Cosgrove, Meng-xing TangAbstract:Non-linear propagation of ultrasound creates artifacts in Contrast-enhanced ultrasound images that significantly affect both qualitative and quantitative assessments of tissue perfusion. This article describes the development and evaluation of a new algorithm to correct for this artifact. The correction is a post-processing method that estimates and removes non-linear artifact in the Contrast-specific image using the simultaneously acquired B-mode image data. The method is evaluated on carotid artery flow phantoms with large and small vessels containing microbubbles of various concentrations at different acoustic pressures. The algorithm significantly reduces non-linear artifacts while maintaining the Contrast Signal from bubbles to increase the Contrast-to-tissue ratio by up to 11 dB. Contrast Signal from a small vessel 600 μm in diameter buried in tissue artifacts before correction was recovered after the correction.
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Dual shear wave induced laser speckle Contrast Signal and the improvement in shear wave speed measurement
Biomedical optics express, 2015Co-Authors: Yi Cheng, Robert J. Eckersley, Daniel S. Elson, Meng-xing TangAbstract:Shear wave speed is quantitatively related to tissue viscoelasticity. Previously we reported shear wave tracking at centimetre depths in a turbid optical medium using laser speckle Contrast detection. Shear wave progression modulates displacement of optical scatterers and therefore modulates photon phase and changes the laser speckle patterns. Time-resolved charge-coupled device (CCD)-based speckle Contrast analysis was used to track shear waves and measure the time-of-flight of shear waves for speed measurement. In this manuscript, we report a new observation of the laser speckle Contrast difference Signal for dual shear waves. A modulation of CCD speckle Contrast difference was observed and simulation reproduces the modulation pattern, suggesting its origin. Both experimental and simulation results show that the dual shear wave approach generates an improved definition of temporal features in the time-of-flight optical Signal and an improved Signal to noise ratio with a standard deviation less than 50% that of individual shear waves. Results also show that dual shear waves can correct the bias of shear wave speed measurement caused by shear wave reflections from elastic boundaries.