Search results for "artificial"
showing 10 items of 7394 documents
Constraints representing a meta-stable régime facilitate exploration during practice and transfer of learning in a complex multi-articular task
2018
Previous investigations have shown that inducing meta-stability\ud in behavior can be achieved by overlapping affordances through constraint\ud manipulation, allowing cooperative and competitive tendencies to\ud functionally coexist. The purpose of this paper was to test a number of\ud conditions applying these design principles on performance during skills\ud practice and transfer. Of additional interest, was whether the existing\ud skill level interacted with the environmental properties of the\ud experimental tasks (varying indoor climbing routes). Two skill groups\ud practised on three routes per session over four separate sessions. At the\ud end of the final session, climbers undertook…
Effect of Simulated IOL Tilt and Decentration on Spherical Aberration After Hyperopic LASIK for Different Intraocular Lenses
2011
PURPOSE: To evaluate visual quality differences among intraocular lenses (IOLs) in patients with previous hyperopic laser ablations and to assess the impact of decentration and tilt of IOLs on visual quality. METHODS: An adaptive optics visual simulator was used to simulate the wavefront aberration pattern of one aberration-correcting IOL (AcrySof IQ SN60WF, Alcon Laboratories Inc) and two spherical IOLs with different amounts of positive spherical aberration (Akreos Adapt [Bausch & Lomb] and Triplato [AJL Ophthalmic]) in five situations—centered, 0.2 mm and 0.4 mm of decentration, and 2° and 4° of tilt—in two groups: simulated low hyperopic laser corneal ablation (low hyperopia group)…
Visual simulation through different intraocular lenses using adaptive optics: Effect of tilt and decentration
2011
Purpose To analyze visual quality differences between intraocular lenses (IOLs) and assess the impact of IOL decentration and tilt on visual quality. Setting University of Valencia, Valencia, Spain. Design Cohort study. Methods The crx1 adaptive optics visual simulator was used to simulate the wavefront aberration pattern of 2 commercially available aspheric aberration-correcting IOLs (Acrysof IQ SN60WF and Tecnis ZA9003) and 2 spherical IOLs (Akreos Adapt and Triplato) in 5 situations: centered, decentered 0.2 mm and 0.4 mm, and tilted 2 degrees and 4 degrees. Monocular distance visual acuity at 100%, 50%, and 10% contrast and the depth of focus were measured. Results Ten eyes of 10 patien…
A finite element-based machine learning approach for modeling the mechanical behavior of the breast tissues under compression in real-time
2017
[EN] This work presents a data-driven method to simulate, in real-time, the biomechanical behavior of the breast tissues in some image-guided interventions such as biopsies or radiotherapy dose delivery as well as to speed up multimodal registration algorithms. Ten real breasts were used for this work. Their deformation due to the displacement of two compression plates was simulated off-line using the finite element (FE) method. Three machine learning models were trained with the data from those simulations. Then, they were used to predict in real-time the deformation of the breast tissues during the compression. The models were a decision tree and two tree-based ensemble methods (extremely…
Dynamic image denoising for voxel-wise quantification with Statistical Parametric Mapping in molecular neuroimaging.
2018
Purpose PET and SPECT voxel kinetics are highly noised. To our knowledge, no study has determined the effect of denoising on the ability to detect differences in binding at the voxel level using Statistical Parametric Mapping (SPM). Methods In the present study, groups of subject-images with a 10%- and 20%- difference in binding of [123I]iomazenil (IMZ) were simulated. They were denoised with Factor Analysis (FA). Parametric images of binding potential (BPND) were produced with the simplified reference tissue model (SRTM) and the Logan non-invasive graphical analysis (LNIGA) and analyzed using SPM to detect group differences. FA was also applied to [123I]IMZ and [11C]flumazenil (FMZ) clinic…
Realignment of myocardial first-pass MR perfusion images using an automatic detection of the heart-lung interface
2004
International audience; Abstract: Magnetic resonance first-pass imaging of a bolus of contrast agent is well adapted to distinguish normal and hypoperfused areas of the myocardium. In most cases, the signal intensity-time curves in user defined regions of interest (ROI) are studied. As image acquisition is ECG-gated, the images are acquired at the same moment in the cardiac cycle, and the basic shape of the heart is similar from one view to the next. However, superficial respiratory motion can displace the heart in the short-axis plane. The aim of this study is to correct for the respiratory motion of the heart by performing an automatic realignment of the myocardial ROI based on a method t…
An algorithm for oncologic scalp reconstruction.
2010
Background: Modern reconstructive surgery allows for radical resection and reconstruction of any scalp tumor. However, a significant number of patients are still not treated optimally because of incomplete reconstructive guidelines. Methods: The treatment of scalp tumors was documented in 60 patients over a 10-year period. Data regarding tumor type, size, and localization; reconstructive procedure; oncologic, functional, and aesthetic outcome; and complications were collected and analyzed retrospectively. These data were correlated to recurrence and survival rates. The findings extracted from the data were amalgamated to produce the proposed reconstructive algorithm. Results: Five reconstru…
Humidity of Anaesthetic Gases with Respect to Low Flow Anaesthesia
1994
It has been demonstrated in an experimental study in swine using the scanning electron microscope that a rebreathing technique utilising minimal fresh gas flowrates significantly improves climatization of anaesthetic gases. Consequently, effects of various anaesthetic techniques on airway climate must be assessed, which covers the need for suitable measuring devices. Basic principles and methods of humidity measurement in flowing anaesthetic gases include gravimetric hygrometry, dew point hygrometry, wet-dry bulb psychrometry, mass spectrometry, spectroscopic hygrometry and electrical hygrometry. A custom-made apparatus for continuous measurement of humidity and temperature in the inspired…
Size invariance in visual number discrimination
1991
This study deals with the observer's ability to discriminate the numerosity of two random dot-patterns irrespective of their relative size. One of these two patterns was a reference one that was always composed of 32 dots randomly distributed within a K x K invisible square window (K = 1.92 degrees). The second one was the test pattern with one of the five magnifications (K = 0.64 degrees, 1.28 degrees, 1.92 degrees, 2.56 degrees, 3.20 degrees) and the relative number of dots varied on 11 levels (N = -15, -12, -9, -6, -3, 0, 3, 6, 9, 12, or 15 dots). The observer's task was to indicate which of the two patterns contained more dots. The results show that the stimulus size, as an irrelevant s…
Validation of ThermoHuman automatic thermographic software for assessing foot temperature before and after running
2020
The aim of the study was to evaluate an automatic thermographic software package (ThermoHuman®) for assessing skin temperature on the soles of the feet before and after running and to compare it with two manual definitions of the regions of interest (ROIs). 120 thermal images of the soles of the feet of 30 participants, at two measurement points (before and after running 30 min) and on two measurement days were analyzed. Three different models of thermographic image analyses were used to obtain the mean temperature of 9 ROIs: A) ThermoHuman (automatic definition of ROIs using ThermoHuman® software), B) Manual (manual delimitation of ROIs by proportion criteria), and C) Manual-TH (manual del…