884 resultados para detection performance


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Object tracking with subpixel accuracy is of fundamental importance in many fields since it provides optimal performance at relatively low-cost. Although there are many theoretical proposals that lead to resolution increments of several orders of magnitude, in practice, this resolution is limited by the imaging systems. In this paper we propose and demonstrate through numerical models a realistic limit for subpixel accuracy. The final result is that maximum achievable resolution enhancement is connected with the dynamic range of the image, i.e. the detection limit is 1/2^(nr.bits). Results here presented may help to proper design of superresolution experiments in microscopy, surveillance, defense and other fields.

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Object tracking with subpixel accuracy is of fundamental importance in many fields since it provides optimal performance at relatively low cost. Although there are many theoretical proposals that lead to resolution increments of several orders of magnitude, in practice this resolution is limited by the imaging systems. In this paper we propose and demonstrate through simple numerical models a realistic limit for subpixel accuracy. The final result is that maximum achievable resolution enhancement is connected with the dynamic range of the image, i.e., the detection limit is 1/2∧(nr.bits). The results here presented may aid in proper design of superresolution experiments in microscopy, surveillance, defense, and other fields.

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But: La perte unilatérale du cortex visuel postérieur engendre une cécité corticale controlatérale à la lésion, qu’on appelle hémianopsie homonyme (HH). Celle-ci est notamment accompagnée de problèmes d’exploration visuelle dans l’hémichamp aveugle dus à des stratégies oculaires déficitaires, qui ont été la cible des thérapies de compensation. Or, cette perte de vision peut s’accompagner d’une perception visuelle inconsciente, appelée blindsight. Notre hypothèse propose que le blindsight soit médié par la voie rétino-colliculaire extrastriée, recrutant le colliculus supérieur (CS), une structure multisensorielle. Notre programme a pour objectif d’évaluer l’impact d’un entraînement multisensoriel (audiovisuel) sur la performance visuelle inconsciente des personnes hémianopsiques et les stratégies oculaires. Nous essayons, ainsi, de démontrer l’implication du CS dans le phénomène de blindsight et la pertinence de la technique de compensation multisensorielle comme thérapie de réadaptation. Méthode: Notre participante, ML, atteinte d’une HH droite a effectué un entraînement d’intégration audiovisuel pour une période de 10 jours. Nous avons évalué la performance visuelle en localisation et en détection ainsi que les stratégies oculaires selon trois comparaisons principales : (1) entre l’hémichamp normal et l’hémichamp aveugle; (2) entre la condition visuelle et les conditions audiovisuelles; (3) entre les sessions de pré-entraînement, post-entraînement et 3 mois post-entraînement. Résultats: Nous avons démontré que (1) les caractéristiques des saccades et des fixations sont déficitaires dans l’hémichamp aveugle; (2) les stratégies saccadiques diffèrent selon les excentricités et les conditions de stimulations; (3) une adaptation saccadique à long terme est possible dans l’hémichamp aveugle si l’on considère le bon cadre de référence; (4) l’amélioration des mouvements oculaires est liée au blindsight. Conclusion(s): L’entraînement multisensoriel conduit à une amélioration de la performance visuelle pour des cibles non perçues, tant en localisation qu’en détection, ce qui est possiblement induit par le développement de la performance oculomotrice.

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Federal Transit Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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Federal Highway Administration, Office of Safety and Traffic Operations Research and Development, McLean, Va.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Office of Driver and Pedestrian Research, Washington, D.C.

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Mode of access: Internet.

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Thesis (Ph.D.)--University of Washington, 2016-04

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The authors describe a reverse-phase high-performance liquid chromatography-electrospray-tandem mass spectrometry method for the measurement of nicotine in human plasma. Samples (500 muL) with added deuterium-labeled d(3)-nicotine as an internal standard (IS) were treated with a 2-step process of ether extraction (6 mL) followed by back-extraction into 0.1% formic acid (50 muL). Chromatography was performed on a phenyl Novapak column with a mobile phase consisting of 50% 10 mM ammonium fortriate (pH 3.3) and acetonitrile (50:50, vol/vol). A flow rate of 0.2 mL/min resulted in a total analysis time of 5 minutes per sample. Mass spectrometric detection was by selected reactant monitoring (nicotine m/z 163.2 --> 130.2; IS m/z 166.2 --> 87.2). The assay was linear from 0.5 to 100 mug/L (r > 0.993, n = 9). The accuracy and imprecision of the method for quality control sampleswere 87.5% to 113% and < 10.2%, respectively. Interday accuracy and imprecision at the limit of quantification (0.5 mug/L) was 113% and 7.2% (n = 4). The process efficiency for nicotine in plasma was > 75%. The method described has good process efficiency, stabilized nicotine, avoided concentration steps, and most importantly minimized potential contamination. Further, we have established that water-based standards and controls are interchangeable with plasma-based samples. This method was used successfully to measure the pharmacokinetic profiles of subjects involved in the development of an aerosol inhalation drug delivery system.

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A simple method for the measurement of the active leflunomide metabolite A77 1726 in human plasma by HPLC is presented. The sample workup was simple, using acetonitrile for protein precipitation. Chromatographic separation of A77 1726 and the internal standard, alpha-phenylcinnamic acid, was achieved using a C-18 column with UV detection at 305 nm. The assay displayed reproducible linearity for A77 1726 with determination coefficients (r(2)) > 0.997 over the concentration range 0.5-60.0 mug/ml. The reproducibility (%CV) for intra- and inter-day assays of spiked controls was

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The observation that snakes and spiders are found faster among flowers and mushrooms than vice versa and that this search advantage is independent of set size supports the notion that fear-relevant stimuli are processed preferentially in a dedicated fear module. Experiment I replicated the faster identification of snakes and spiders but also found a set size effect in a blocked, but not in a mixed-trial, sequence. Experiment 2 failed to find faster identification of snake and spider deviants relative to other animals among flowers and mushrooms and provided evidence for a search advantage for pictures of animals, irrespective of their fear relevance. These findings suggest that results from the present visual search task cannot support the notion of preferential processing of fear relevance.