53 research outputs found
Banach fixed-point between SEM image and EBSD diffraction pattern from a cylindrically symmetric rotating crystal
The Kikuchi bands arise from Bragg diffraction of incoherent electrons
scattered within a crystalline specimen and can be observed in both the
transmission and reflection modes of scanning electron microscopy (SEM).
Converging, rocking, or grazing incidence beams must be used to generate
divergent electron sources to obtain the Kikuchi pattern. This paper report the
observation of Kikuchi pattern from SEM images of an exceptional rotating
crystal with continuous rotation in the local crystal direction and satisfying
cylindrical symmetry, named a cylindrically symmetric rotating crystal. SEM
images of cylindrically symmetric rotating crystals reflect the interactions
between electrons and the sample in both the real- and momentum-space.
Furthermore, we identify an unexpected mathematical relationship between the
electron backscattered diffraction (EBSD) Kikuchi pattern matrix map and the
SEM image of the present sample which can be rationalized as a concrete example
of the Banach fixed-point theorems in the field of EBSD technique
An unusual association of diffuse adenomyomatosis with dysplastic adenoma in chronic calculous cholecystitis: case presentation
<p>Abstract</p> <p>Background</p> <p>Gallbladder adenomyomatosis is an epithelial proliferation and hypertrophy of the muscularis mucosae of the gallbladder. Rokitansky-Aschoff sinuses are a characteristic of this condition. The segmental adenomyomatosis has a higher risk of developing into gallbladder carcinoma, especially in the fundal region of elderly patients.</p> <p>We report the case of a patient affected by chronic calculous cholecystitis with diffuse adenomyomatosis associated with dysplastic adenoma.</p> <p>Case presentation</p> <p>An 81-year-old woman presented at our hospital with a 1-year history of intermittent pain localized at the right upper abdominal quadrant, without diffusion to any other body part. On physical examination the abdomen was soft, not distended, and tender to palpation in the right upper quadrant. Murphy sign was negative. Laboratory tests were normal. The patient was scheduled for a laparoscopic cholecystectomy, and neither endoscopic ultrasonographic scan nor magnetic resonance imaging was performed. The operation, performed after obtaining informed consent, was uncomplicated and the intra-operative pathological examination showed no malignancy. The definitive pathological examination of the gallbladder showed: multiple stones of cholesterol origin; diffuse mucosal adenomyomatosis; and a 1.1 cm pedunculated mass localized at the fundus, whose surface was lumpy. This mass was diagnosed as an adenoma with multiple areas of severe dysplasia.</p> <p>Conclusions</p> <p>The adenoma of the gallbladder, together with the dysplasia, represents a biological carcinogenetic model. Carcinoma has rarely been reported in adenomyomatosis. Degenerative risk suggests surgery should be mandatory when there is a concomitant presence of large adenoma and adenomyomatosis.</p
The cerebral correlates of different types of perseveration in the Wisconsin Card Sorting Test
Objectives: To explore the neural substrates corresponding to the perseverative errors in the Wisconsin Card Sorting Test (WCST). Methods: The study examined the correlations between the WCST performances and the SPECT measurements of regional cerebral blood flow (rCBF) in subjects with neurodegenerative dementia. Negative non-linear correlations between the rCBF and the two different types of the perseverative errors ("stuck-in-set" and "recurrent" perseverative errors) were calculated on a voxel basis and volume-of-interest basis in the mixed groups of 72 elderly and dementia patients. Results: The stuck-in-set perseverative error was associated with the reduced rCBF in the rostrodorsal prefrontal cortex, whereas the recurrent perseverative error was related to the left parietal activity but not to the prefrontal activity. Conclusions: These findings augment evidence that the rostrodorsal prefrontal cortex crucially mediates attentional set shifting, and suggest that the stuck-in-set perseverative errors would be a true pathognomonic sign of frontal dysfunction. Moreover, this study shows that the recurrent perseverative errors may not be associated closely with the prefrontal function, suggesting that this error and the stuck-in-set error should be differentially estimated in the WCST
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