Search results for "contour"
showing 10 items of 99 documents
Contour integration with corners.
2016
Contour integration refers to the ability of the visual system to bind disjoint local elements into coherent global shapes. In cluttered images containing randomly oriented elements a contour becomes salient when its elements are coaligned with a smooth global trajectory, as described by the Gestalt law of good continuation. Abrupt changes of curvature strongly diminish contour salience. Here we show that by inserting local corner elements at points of angular discontinuity, a jagged contour becomes as salient as a straight one. We report results from detection experiments for contours with and without corner elements which indicate their psychophysical equivalence. This presents a challeng…
1 Hz rTMS enhances extrastriate cortex activity in migraine
2003
We recently reported a paradoxical facilitatory effect of 1 Hz repetitive TMS (rTMS) on the primary visual cortex in migraine possibly due to the failure of inhibitory circuits, unable to be upregulated by low frequency rTMS. To investigate if inhibitory circuit dysfunction extends beyond striate cortex in migraine with aura, we studied the effects of 1 Hz rTMS over the right extrastriate cortex on perception of illusory contours in these patients. Low-frequency rTMS enhanced activity of extrastriate cortex in migraineurs, speeding up reaction times on illusory contour perception. This finding supports the view of a failure of inhibitory circuits also involving the extrastriate cortex in mi…
Requirement and postoperative outcomes of abdominal panniculectomy alone or in combination with other procedures in a bariatric surgery unit.
2009
Abstract Background A high percentage of patients present with redundant skin folds after bariatric surgery. This study aims to quantify the need for panniculectomy after open bariatric surgery and to analyze the postoperative outcomes. Methods A retrospective cohort study was performed. The patients were divided into 2 groups: group DLP, patients who underwent an abdominal panniculectomy alone and group DLP+, those who underwent panniculectomy in association with another surgical procedure. Results Four hundred forty-six patients underwent open bariatric surgery and 130 patients (29%) subsequently required an abdominal dermolipectomy. Seventy-six percent presented also incisional hernia an…
Automatic determination of aortic compliance with cine-magnetic resonance imaging - An application of fuzzy logic theory
2002
International audience; Abstract: RATIONALE AND OBJECTIVES. Aortic compliance is defined as the relative change in aortic cross-sectional area divided by the change in arterial pressure. Magnetic resonance imaging (MRI) is a useful imaging modality for the noninvasive evaluation of aortic compliance. However, manual tracing of the aortic contour is subject to important interobserver variations. To estimate the aortic compliance from cine-MRI, a method based on fuzzy logic theory was elaborated. MATERIALS AND METHODS. Seven healthy volunteers and eight patients with Marfan syndrome were examined using an ECG gated cine-MRI sequence. The aorta was imaged in the transverse plane at the level o…
Seismic stratigraphy of upper Quaternary shallow-water contourite drifts in the Gulf of Taranto (Ionian Sea, southern Italy)
2018
Abstract The occurrence of articulated seafloor morphology over continental shelf-upper slope environments, may result in a significant change in the patterns and intensity of basin-scale thermohaline circulation during eustatic sea-level fluctuations. These changes may cause, in turn, erosion, deposition and/or transport of sediments at the seafloor, to form shallow-water contourite drifts. Here we investigate this process in the NW sector of the Gulf of Taranto (Ionian Sea) during and following the Last Glacial Maximum (LGM), by integrating multibeam bathymetric data, ultra-high resolution seismic-reflection data and gravity core data. Sea level fall caused subaerial exposure of the summi…
A New Framework for the Extraction of Contour Lines in Scanned Topographic Maps
2010
3D simulations requested in various applications had led to the development of fast and accurate terrain topography measurement techniques. In this paper, we are presenting a novel framework dedicated to the semiautomatic processing of scanned maps, extracting the contour lines vectors and building a digital elevation model on their basis, fulfilled by a number of stages discussed in detail throughout the work. Despite the good results obtained on a large amount of scanned maps, a completely automatic map processing technique is unrealistic and remains an open problem.
Computation of the area in the discrete plane: Green’s theorem revisited
2017
International audience; The detection of the contour of a binary object is a common problem; however, the area of a region, and its moments, can be a significant parameter. In several metrology applications, the area of planar objects must be measured. The area is obtained by counting the pixels inside the contour or using a discrete version of Green's formula. Unfortunately, we obtain the area enclosed by the polygonal line passing through the centers of the pixels along the contour. We present a modified version of Green's theorem in the discrete plane, which allows for the computation of the exact area of a two-dimensional region in the class of polyominoes. Penalties are introduced and …
Mammogram segmentation by contour searching and massive lesion classification with neural network
2004
The mammography is the most effective procedure for an early diagnosis of the breast cancer. In this paper, an algorithm for detecting massive lesions in mammographic images will be presented. The database consists of 3762 digital images acquired in several hospitals belonging to the MAGIC-5 collaboration. A reduction of the surface under investigation is achieved, without loss of meaningful information, through segmentation of the whole image, by means of a ROI Hunter algorithm. In the following classification step, feature extraction plays a fundamental role: some features give geometrical information, other ones provide shape parameters. Once the features are computed for each ROI, they …
Comparison between doppler-echocardiography and uncalibrated pulse contour method for cardiac output measurement. a multicenter observational study
2016
Objectives: Echocardiography and pulse contour methods allow, respectively, noninvasive and less invasive cardiac output estimation. The aim of the present study was to compare Doppler echocardiography with the pulse contour method MostCare for cardiac output estimation in a large and nonselected critically ill population. Design: A prospective multicenter observational comparison study. Setting: The study was conducted in 15 European medicosurgical ICUs. Patients: We assessed cardiac output in 400 patients in whom an echocardiographic evaluation was performed as a routine need or for cardiocirculatory assessment. Interventions: None. Measurements and Main Results: One echocardiographic car…
Use of response factorial design for process optimization of basic dye adsorption onto activated carbon derived from Persea species
2017
Abstract Full factorial design is a powerful and efficient mathematical approach widely applied in the optimization of response. The important parameters which affect the removal efficiency of methylene blue such temperature, initial pH of the solution, concentration and adsorbent dosage were optimized. They coded as A, B, C and D, consecutively, and were investigated at two levels (+ 1 and − 1). A linear mathematical model representing the influence of the different variables and their interactions was obtained. Main effect, Normal probability plot of residuals, analysis of variance (ANOVA), surface plots, and contour plots were used to study the effects and interaction effects between ope…