Bisection Algorithm for Computing the Frequency Response Gain of Sampled-Data Systems - Infinite-Dimensional Congruent Transformation Approach

This paper derives a bisection algorithm for computing the frequency response gain of sampled-data systems with their intersample behavior taken into account. The properties of the infinite-dimensional congruent transformation (i.e., the Schur complement arguments and the Sylvester law of inertia) play a key role in the derivation. Specifically, it is highlighted that counting up the numbers of the negative eigenvalues of self-adjoint operators is quite important for the computation of the frequency response gain. This contrasts with the well-known arguments on the related issue of the sampled-data problem, where the key role is played by the positivity of operators and the loop-shifting technique. The effectiveness of the derived algorithm is demonstrated through a numerical example. Index Terms---Bisection algorithm, frequency response gain, numerical computation, sampled-data systems, Schur complement arguments. I

Neural Correlates of Color-Selective Metacontrast in Human Early Retinotopic Areas

Metacontrast is a visual illusion in which the visibility of a target stimulus is virtually lost when immediately followed by a nonoverlapping mask stimulus. For a colored target, metacontrast is color-selective, with target visibility markedly reduced when the mask and target are the same color, but only slightly reduced when the colors differ. This study investigated neural correlates of color-selective metacontrast for cone-opponent red and green stimuli in the human V1, V2, and V3 using functional magnetic resonance imaging. Neural activity was suppressed when the target was rendered less visible by the same-colored mask, and the suppression was localized in the cortical region retinotopically representing the target, correlating with the perceptual topography of visibility/invisibility rather than the physical topography of the stimulus. Retinotopy-based group analysis found that activity suppression was statistically significant for V2 and V3 and that its localization to the target region was statistically significant for V2. These results suggest that retinotopic color representations in early visual areas, especially in V2, are closely linked to the visibility of color

A case of ovarian clear cell carcinoma arising from ovarian mature cystic teratoma

Abstract Background It is well known that ovarian mature cystic teratomas (MCTs) occasionally go through malignant transformations. Among these, approximately 75% of histological types are squamous cell carcinoma, with the other types being exceptionally rare. We report an extremely rare case of ovarian clear cell carcinoma arising from ovarian mature cystic teratoma. Case presentation The case was a 71-year-old woman with abdominal distention. Ultrasonography and magnetic resonance imaging showed a huge mass in her abdominal cavity. Fluorodeoxyglucose-positron emission tomography (FDG-PET) showed FDG uptake not only in the pelvic tumor but also in the hepatic nodule, thus suggesting metastases. We performed a total abdominal hysterectomy, bilateral salpingo-oophorectomy, and an omentectomy. The pathological diagnosis showed clear cell carcinoma of the right ovary which arose from the MCT with malignant transformation pT2aNXM1. Although the patient underwent chemotherapy, she died after 17 months. Conclusion This case is histologically characteristic of the proof of transition from simple squamous epithelium via simple glandular epithelium to papillary change with atypia. This is the first case report of unaccompanied clear cell carcinoma arising from MCT reported in English literatures