The Computation of Surface Lightness in Simple and Complex Scenes

The present thesis examined how reflectance properties and the complexity of surface mesostructure (small-scale surface relief) influence perceived lightness in centresurround displays. Chapters 2 and 3 evaluated the role of surface relief, gloss, and interreflections on lightness constancy, which was examined across changes in background albedo and illumination level. For surfaces with visible mesostructure (“rocky” surfaces), lightness constancy across changes in background albedo was better for targets embedded in glossy versus matte surfaces. However, this improved lightness constancy for gloss was not observed when illumination varied. Control experiments compared the matte and glossy rocky surrounds to two control displays, which matched either pixel histograms or a phase-scrambled power spectrum. Lightness constancy was improved for rocky glossy displays over the histogram-matched displays, but not compared to phase-scrambled variants of these images with equated power spectrums. The results were similar for surfaces rendered with 1, 2, 3 and 4 interreflections. These results suggest that lightness perception in complex centre-surround displays can be explained by the distribution of contrast across space and scale, independently of explicit information about surface shading or specularity. The results for surfaces without surface relief (“homogeneous” surfaces) differed qualitatively to rocky surfaces, exhibiting abrupt steps in perceived lightness at points at which the targets transitioned from being increments to decrements. Chapter 4 examined whether homogeneous displays evoke more complex mid-level representations similar to conditions of transparency. Matching target lightness in a homogeneous display to that in a textured or rocky display required varying both lightness and transmittance of the test patch on the textured display to obtain the most satisfactory matches. However, transmittance was only varied to match the contrast of targets against homogeneous surrounds, and not to explicitly match the amount of transparency perceived in the displays. The results suggest perceived target-surround edge contrast differs between homogeneous and textured displays. Varying the mid-level property of transparency in textured displays provides a natural means for equating both target lightness and the unique appearance of the edge contrast in homogeneous displays

Characteristic facial dysmorphism, arachnodactyly and mental retardation : another case

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Zimmermann-Laband syndrome in a patient with severe mental retardation

Contains fulltext : 21548___.PDF (publisher's version ) (Open Access

Cri du chat syndrome: Changing phenotype in older patients

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Dysmorphology and mental retardation: molecular cytogenetic studies in dysmorphic mentally retarded patients.

Item does not contain fulltextIn an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 18 patients (16 males and 2 females) with dysmorphic features were selected to perform FISH studies by using subtelomeric probes to discover cryptic terminal deletions or duplications, undetectable with standard banding techniques. In the 13 investigated patients, no abnormalities were found with a selected battery of subtelomeric probes. The results of cryptic chromosomal rearrangement studies are variable but the frequency of positive diagnostic findings seems to be lower than previously expected

Fountain syndrome: further delineation of the clinical syndrome and follow-up data

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The del(2)(q32.2q33) deletion syndrome defined by clinical and molecular characterization of four patients.

Item does not contain fulltextWe report four patients with an interstitial deletion of chromosome 2q32-->2q33. They presented similar clinical findings including pre- and postnatal growth retardation, distinct facial dysmorphism, thin and sparse hair and fair built, micrognathia, cleft or high palate, relative macroglossia, dacrocystitis, persisting feeding difficulties, inguinal hernia and broad based gait. All were severely mentally retarded. Three patients had a specific behavioral phenotype with hyperactivity and motor restlessness, chaotic behavior, happy-personality but with periods of aggression and anxiety, sleeping problems and self-mutilation. (head-banging). Array CGH and fluorescence in situ hybridization (FISH) allowed us to delineate the deletion size and showed that the four patients share a 8.1 Mb minimal deleted region. Reviewing additional nine case reports of patients with similar deletions showed striking phenotypic similarities which enabled the delineation of the 2q32.2q33 syndrome. Deletion of 2q32 has been also associated with the wrinkly skin syndrome (WWS) and isolated cleft palate. Although the patients presented here shared many aspects of WWS, they did not had the wrinkly skin. All patients had a cleft or high palate, most likely as a result of hemizygosity for SATB2. A potential commonly deleted interval of the three patients with behavioral problems, excluding the deletion in the patient without behavioral problems, is at most 0.5 Mb in size harboring only two genes

Definition of a critical region on chromosome 18 for congenital aural atresia by arrayCGH.

Item does not contain fulltextDeletions of the long arm of chromosome 18 occur in approximately 1 in 10,000 live births. Congenital aural atresia (CAA), or narrow external auditory canals, occurs in approximately 66% of all patients who have a terminal deletion 18q. The present report describes a series of 20 patients with CAA, of whom 18 had microscopically visible 18q deletions. The extent and nature of the chromosome-18 deletions were studied in detail by array-based comparative genomic hybridization (arrayCGH). High-resolution chromosome-18 profiles were obtained for all patients, and a critical region of 5 Mb that was deleted in all patients with CAA could be defined on 18q22.3-18q23. Therefore, this region can be considered as a candidate region for aural atresia. The array-based high-resolution copy-number screening enabled a refined cytogenetic diagnosis in 12 patients. Our approach appeared to be applicable to the detection of genetic mosaicisms and, in particular, to a detailed delineation of ring chromosomes. This study clearly demonstrates the power of the arrayCGH technology in high-resolution molecular karyotyping. Deletion and amplification mapping can now be performed at the submicroscopic level and will allow high-throughput definition of genomic regions harboring disease genes