The Trace transform and its applications

The Trace transform proposed, a generalization of the Radon transform, consists of tracing an image with straight lines along which certain functionals of the image function are calculated. Different functionals that can be used may be invariant to different transformations of the image. The paper presents the properties the functionals must have in order to be useful in three different applications of the method: construction of invariant features to rotation, translation and scaling of the image, construction of sensitive features to the parameters of rotation, translation and scaling of the image, and construction of features that may correlate well with a certain phenomenon we wish to monitor     

Reverse engineering the way humans rank textures

We argue that in order to understand which features are used by humans to group textures, one must start by computing thousands of features of diverse nature, and select from those features those that allow the reproduction of perceptual groups or perceptual ranking created by humans. We use the Trace transform to produce such features here. We compare these features with those produced from the co-occurrence matrix and its variations. We show that when one is not interested in reproducing human behaviour, the elements of the co-occurrence matrix used as features perform best in terms of texture classification accuracy. However, these features cannot be “trained” or “selected” to imitate human ranking, while the features produced from the Trace transform can. We attribute this to the diverse nature of the features computed from the Trace transform.

Stress distributions and intensities at corners of equilateral triangular holes

The problem of the stress distribution in an infinite medium which was weakened by an equilateral triangular hole under tension at infinity, was studied. The triangular hole and its exterior was conformally mapped into the interior of a unit circle by using the Schwarz-Christoffel transformation. The stress function (z) was defined by Muskhelishvili's complex-function theory and the conformal mapping technique. The Schwarz-Christoffel transformation was expressed as a truncated series with a finite numbers of terms. This function represents an equilateral triangle with rounded-off corners mapped into the unit circle. A change of the stress field around the triangular hole was investigated.It was shown that for the transformation function with two-or more-terms of the series, the stress field along the boundary of the respective triangular hole remained unchanged, except for the values of stresses in the near vicinity of the apieces of the corners.It was shown that by introducing substitute singular points lying in the vicinity of the centers of curvature of the rounded corners, the discrepancies in stresses appearing in their vicinity disappeared, and their exact values were attained. These points correspond to the points of the zeroing of the first derivative of the mapping function and coincide with the centers of the initial curves of the caustics traced at each corner for the particular loading mode of the plate. All these results were experimentally verified by using the optical method of reflected caustics.

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Résumé On étudie le problème de la distribution des contraintes dans un milieu infini, affaibli par un trou en forme de triangle équilatéral, et soumis à tension à l'infini. En utilisant une transformée de Schwarz-Christoffel, on a fait une transposition conforme du trou triangulaire et de sa zone extérieure, à un cercle unitaire et sa zone intérieure. La fonction de contrainte (Z) a été définie par la théorie de Muskhelishvili et par la technique de la représentation conforme, la transformée de Schwarz-Christoffel étant exprimée par une série tronquée à nombre de termes fini. Cette fonction représente un triangle équilatéral aux angles arrondis, inscrit dans le cercle unitaire. On a étudié une modification du champ de contraintes autour des trou triangulaire. On montre que, pour une fonction de transformée à deux termes ou davantage, le champ de contraintes le long du contour du trou triangulaire correspondant demeure constant, à l'exception des valeurs des contraintes au voisinge immédiat des angles. Si on introduit des points singuliers au voisinage des centres de courbure des arrondis d'angle, les différences apparaissant dans les contraintes aux angles s'estompent, et les valeurs exactes sont atteintes. Les points en question correspondent aux points obtenus en annulant la dérivée première de la fonction. Ils coïnciden avec les centres des caustiques tracées a chaque angle du ton pour le mode particulier de charge auquel est soumis le milieu.Tous les résultats obtenus ont été vérifiés expérimentalement en utilisant la méthode optique des caustiques réfléchies.

     

Relational space classification for malaria diagnosis

We present a study of sera derived from the malaria medical analysis of 189 subjects. The feature space is 18-dimensional and each serum is represented by a binary number. The subjects are divided into three different groups: no malaria, clinical malaria and asymptomatic subjects. We studied the main characteristics of the data and we selected 7 out of the 18 antigens as the most important for group discrimination. We propose a novel representation of the data in the so-called relational space, where the coded data of pairs of patients are plotted. We are able to separate the groups with 58% accuracy, about 15% points better than several conventional methods with which we compare our results.     

Robot handling of flat textile materials

The authors present a robotic system incorporating vision and force/torque sensing for handling flat textile materials and describe the results of experiments to measure the accuracy and reliability of the system for a variety of representative handling tasks for textile materials     

Neurovisual impairment: a frequent complication of alpha-interferon treatment in chronic viral hepatitis

Following our earlier observation of clinically evident optic tract neuropathy in patients receiving low-dose interferon (IFN) therapy, we prospectively evaluated 53 consecutive patients treated for chronic hepatitis B or C with a median dose of 3 MU of IFN-a2b thrice weekly. Measurements included routine ophthalmologic evaluation and recordings of visual evoked responses (VER), electroretinograms (ERG), visual acuity, and visual fields, before, at the end of IFN treatment, and at follow-up visits. Baseline P100 latencies of VERs (base-VER) were abnormally prolonged in 24 patients (32 of 106 eyes, 30.2%); age was the only significant covariate associated with increased risk for an abnormal base-VER by multiple logistic regression (relative risk [RR] 5.3 per each 5-year increase in age). In 45 patients (74 eyes) with normal baseline P100 latencies, the end-of-treatment VERs (end-VER) were significantly prolonged compared with baseline, becoming abnormal in 11 (15 of 74 eyes, 20.3%) (138.8+/-8.7 vs. 117.7+/-5.2 ms, P < .001). This subgroup had older age (59.1+/-11.0 vs. 47.5+/-15.3, P=.007) and reduced visual sensitivity compared with their own pretreatment measurements (24.5+/-1.6 vs. 23.0+/-1.2db, P=.019). Changes of end-VERs by age had a sigmoid distribution with a steep increase of values beyond the 5th decade (R2=.326, P < .001). In a logistic regression model, significant predictors of abnormal end-VERs were, patients' age (RR 5.6 per each 5-year increase), presence of hepatitis B virus (HBV) infection (RR 15.1 compared with hepatitis C virus [HCV] infection) and serum cholesterol levels above 240 mg% (RR 7.1 compared with values < 240 mg%). Subconjunctival hemorrhages were seen in 2 cases and funduscopic examination revealed cotton wool spots in one other. ERG recordings and the P100 amplitude remained unchanged. After stopping IFN, the treatment-associated neurovisual abnormalities reversed to normal in 7 patients (10 of 15 eyes) and persisted in 5 (5 of 15 eyes, 33.3%) for up to 37 (median 7.3) months observation, all patients remaining clinically asymptomatic. In conclusion, subclinical neurovisual impairment is a frequent, largely unrecognized complication of low-dose IFN therapy, and patients with chronic hepatitis B and older age appear to be most susceptible. This apparently innocuous complication is long lasting, possibly irreversible in some patients, with yet undetermined consequences on visual function.     

Chromene-Containing Aromatic Sulfonamides with Carbonic Anhydrase Inhibitory Properties

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the essential reaction of CO₂ hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological conditions. A series of chromene-based sulfonamides were synthesized and tested as possible CA inhibitors. Their inhibitory activity was assessed against the cytosolic human isoforms hCA I, hCA II and the transmembrane hCA IX and XII. Several of the investigated derivatives showed interesting inhibition activity towards the tumor associate isoforms hCA IX and hCA XII. Furthermore, computational procedures were used to investigate the binding mode of this class of compounds, within the active site of hCA IX.     

Nonlinear motion estimation using the supercoupling approach

This paper presents the application of a very efficient multiresolution transformation, which is related to the renormalization group approach of physics, to the problem of motion segmentation. The approach proposed is much faster and yields much better results than the full resolution approach. The problem is formulated as one of global optimization where a cost function is constructed to combine the information obtained by various processors as well as the constraints we impose to the problem. The cost function is optimized using the supercoupling multiresolution approach     

Data mining for large scale 3D seismic data analysis

The automation of the analysis of large volumes of seismic data is a data mining problem, where a large database of 3D images is searched by content, for the identification of the regions that are of most interest to the oil industry. In this paper we perform this search using the 3D orientation histogram as a texture analysis tool to represent and identify regions within the data, which are compatible with a query texture.     

Separable 2-D filters for the detection of ramp edges

The author examines the use of 1-D optimal convolution filters for the detection of ramp edges. The idea is to replace one 2-D convolution by two 1-D ones performed in sequence. The way the parameters of the 1-D filters have to be chosen so that the performance of the operation is not compromised is investigated. The author presents theoretical results and applies them to some real images to show that the quality of the performance remains the same while the efficiency of the operation improves significantly