The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Yuhong V Jiang - One of the best experts on this subject based on the ideXlab platform.
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Indirect Assessment of visual working memory for simple and complex objects
Memory & Cognition, 2008Co-Authors: Tal Makovski, Yuhong V JiangAbstract:Previous research has shown that visual search performance is modulated by the current contents in visual working memory (VWM), even when the contents of VWM are irrelevant to the search task. For example, visual search is faster when the target—rather than a distractor—is surrounded by a shape currently held in VWM. This study uses the modulation of visual search by VWM to investigate properties of VWM. Participants were asked to remember the color or the shape of novel polygons whose “goodness” of figure varied according to Garner’s (1962) rotation and reflection transformation principle. During the memory retention interval, participants searched for a tilted line among vertical lines embedded inside colored polygons. Search was faster when the target—rather than a distractor—was enclosed by the remembered polygons. The congruity effect diminished with increasing memory load and decreasing figure goodness. We conclude that congruity effects in visual search can Indirectly assess VWM representation strength.
R. Dvorak - One of the best experts on this subject based on the ideXlab platform.
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Direct and Indirect Assessment of selenium status in sheep - a comparison
Veterinarni Medicina, 2018Co-Authors: Leoš Pavlata, L. Misurova, Alena Pechová, T. Husakova, R. DvorakAbstract:Pavlata L., A. Pechova, J. Illek: Direct and Indirect Assessment of Selenium Status in Cattle - a Comparison. Acta vet. Brno 2000, 69: 281-287. Selenium concentration and activity of glutathione peroxidase (GSH-Px) as direct and Indirect indicators of selenium status were determined in whole blood samples collected from 326 cattle in 30 herds kept in various regions of the Czech Republic. The GSH-Px activity in the samples was measured by the UV method, using the set supplied by Randox. Selenium in the sample was measured using the hydride technique AAS. The two variables showed a close and significant correlation (r = 0.90; p < 0.01). The regression line, defined by the equation y = 6.44x + 21.4, allowed us to determine the GSH-Px activity of 665.4 µkat.l -1 as equivalent to selenium concentration in whole blood 100 µg.l-1 . Mean selenium concentration and mean GSH-Px activity found in whole blood samples were 78.25 ± 46.67 µg.l-1 and 525.51 ± 335.56 µkat.l-1, respectively. Insufficient or marginal supply of selenium was diagnosed in 64% of the animals in terms of selenium concentration, in 63% of the animals in terms of GSH-Px activity and in 55% of the animals with selenium concentrations
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Direct and Indirect Assessment of selenium status in sheep – a comparison
Veterinární Medicína, 2012Co-Authors: Leoš Pavlata, L. Misurova, Alena Pechová, T. Husakova, R. DvorakAbstract:The aim of this study was to determine the relationship between selenium concentration and activity of glutathione peroxidase (GSH-Px) in the whole blood of sheep and reference ranges for the activity of GSH-Px for evaluation of the selenium status of sheep in the Czech Republic. Selenium concentration and activity of glutathione peroxidase were determined in whole blood samples collected from 92 sheep in six herds. The GSH-Px activity in the samples was measured using the photometric method. Selenium in the sample was measured using the hydride technique atomic absorption spectrometry. Data on both parameters were processed using correlation and regression analysis in order to obtain reference values of GSH-Px for the Indirect evaluation of the selenium status of sheep. The two variables showed a close and significant correlation (r = 0.95; P < 0.01). The regression line, defined by the equation y = 7.5857x – 121.87 (linear) or y = –0.0167x<sup>2</sup> + 11.993x – 355.57 (polynomial), allowed us to determine the GSH-Px activity of 637, resp. 677 μkat/l as equivalent to selenium concentration in whole blood of sheep 100 μg/l. Mean selenium concentration and mean GSH-Px activity found in whole blood samples were 123.42 ± 57.84 μg/l and 814.34 ± 463.64 μkat/l, respectively. In this study, a close dependence of GSH-Px activity on the selenium concentration in the blood of sheep was found. Activity values of GSH-Px were determined for use in the diagnosis of sufficient selenium status in sheep in the Czech Republic (GSH-Px activity greater than 600 μkat/l of whole blood).
N.b. Ebrahimi - One of the best experts on this subject based on the ideXlab platform.
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Indirect Assessment of system reliability
IEEE Transactions on Reliability, 2003Co-Authors: N.b. EbrahimiAbstract:Assessing system-reliability has been a major goal of many people in many walks of life, including those that develop and deploy systems. For that purpose many methods and techniques have been published. However, most of these techniques and methods rely heavily on failure data. Because the design of high-reliability systems generally requires that the individual system components have extremely high reliability, even after long periods of time, and because short product-development times and tightened-budgets imply that reliability tests must be conducted with severe time-constraints, frequently no failures occur during such tests. Thus, there is a growing need to assess reliabilities for complex systems for which it is difficult to collect failure data. This paper focuses on a method that expresses the failure time and consequently the reliability of a system as a function of several explanatory variables (referred to as covariates). Then, the system reliability is assessed Indirectly by using information on these covariates. From a practical viewpoint, this method might be more complicated and difficult to apply. The author still recommends this methodology because there are many situations where it is difficult to have data on failure times of expensive and complex systems, and this method can handle such situations.
Tristan Maerz - One of the best experts on this subject based on the ideXlab platform.
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nondestructive Indirect Assessment of the biomechanical properties of the rat intervertebral disc using contrast enhanced μct
Journal of Orthopaedic Research, 2018Co-Authors: Michael D Newton, Samantha Hartner, Karissa Marie Bassett Gawronski, Erik J Davenport, Shannon C Timmons, Kevin C Baker, Tristan MaerzAbstract:: Mechanical characterization of the intervertebral disc involves labor-intensive and destructive experimental methodology. Contrast-enhanced micro-computed tomography is a nondestructive imaging modality for high-resolution visualization and glycosaminoglycan quantification of cartilaginous tissues. The purpose of this study was to determine whether anionic and cationic contrast-enhanced micro-computed tomography of the intervertebral disc can be used to Indirectly assess disc mechanical properties in an ex vivo model of disc degeneration. L3/L4 motion segments were dissected from female Lewis rats. To deplete glycosaminoglycan, samples were treated with 0 U/ml (Control) or 5 U/ml papain. Contrast-enhanced micro-computed tomography was performed following incubation in 40% Hexabrix (anionic) or 30 mg I/ml CA4+ (cationic) for 24 h (n = 10/contrast agent/digestion group). Motion segments underwent cyclic mechanical testing to determine compressive and tensile modulus, stiffness, and hysteresis. Glycosaminoglycan content was determined using the dimethylmethylene blue assay. Correlations between glycosaminoglycan content, contrast-enhanced micro-computed tomography attenuation, and mechanical properties were assessed via the Pearson correlation. The predictive accuracy of attenuation on compressive properties was assessed via repeated random sub-sampling cross validation. Papain digestion produced significant decreases in glycosaminoglycan content and corresponding differences in attenuation and mechanical properties. Attenuation correlated significantly to glycosaminoglycan content and to all compressive mechanical properties using both Hexabrix and CA4+ . Predictive linear regression models demonstrated a predictive accuracy of attenuation on compressive modulus and stiffness of 79.8-86.0%. Contrast-enhanced micro-computed tomography was highly predictive of compressive mechanical properties in an ex vivo simulation of disc degeneration and may represent an effective modality for Indirectly assessing disc compressive properties. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2030-2038, 2018.
Tal Makovski - One of the best experts on this subject based on the ideXlab platform.
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Indirect Assessment of visual working memory for simple and complex objects
Memory & Cognition, 2008Co-Authors: Tal Makovski, Yuhong V JiangAbstract:Previous research has shown that visual search performance is modulated by the current contents in visual working memory (VWM), even when the contents of VWM are irrelevant to the search task. For example, visual search is faster when the target—rather than a distractor—is surrounded by a shape currently held in VWM. This study uses the modulation of visual search by VWM to investigate properties of VWM. Participants were asked to remember the color or the shape of novel polygons whose “goodness” of figure varied according to Garner’s (1962) rotation and reflection transformation principle. During the memory retention interval, participants searched for a tilted line among vertical lines embedded inside colored polygons. Search was faster when the target—rather than a distractor—was enclosed by the remembered polygons. The congruity effect diminished with increasing memory load and decreasing figure goodness. We conclude that congruity effects in visual search can Indirectly assess VWM representation strength.
