Hiroyuki Hagiwara

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SUMMARY This paper proposes a new architecture for multibit complex bandpass ∆ΣAD modulators with built-in Switched-Capacitor (SC) circuits for application to Low-IF receivers such as used for Bluetooth and WLAN. In the realization of complex bandpass ∆ΣAD modulators, we face the following problems: (i) SNR of AD converter is deteriorated by mis-matches(More)
BACKGROUND Endovascular surgery is being increasingly used as an alternative to craniotomy clipping surgery, especially for aged patients and complicated cases. However, tortuous atherosclerotic arteries sometimes interfere with advancement of catheters so that direct puncture may be necessary. Short guiding catheters for use with this approach have been(More)
We describe the clinicopathological features of 25 brainstem gliomas (BSGs). Twenty BSGs located in the pons and were all in children. Four BSGs located in the medulla oblongata were in 2 children and 2 adults. One (in a child) was located in the midbrain. Radiological findings on MR images were low-intensity on T1 weighted images and high-intensity on T2(More)
SUMMARY We have designed, fabricated and measured a second-order multibit switched-capacitor complex bandpass ∆ΣAD modulator to evaluate our new algorithms and architecture. We propose a new structure of a complex bandpass filter in the forward path with I, Q dynamic matching , that is equivalent to the conventional one but can be divided into two separate(More)
A 55-year old female was referred to the Department of Neurosurgery, Kitasato Hospital, because of a hearing impairment. Neuroimaging revealed a typical meningioma attached to the falx in the right frontal region. During surgery, an encapsulated, circumscribed, reddish-gray, slightly hard tumor attached to the falx was completely removed by an(More)
Hemangioblastoma is a benign tumor of the cerebellum, and treatment involves surgical excision, both as the initial treatment and also in case of recurrence. Recurrence of hemangioblastoma can be local due to incomplete resection or can be distant and separate from the tumor resection region. Local recurrence can largely be avoided by verifying for any(More)
Tightness of the lateral ventricle may result in mechanical obstruction of an external ventricular drain (EVD). We propose a modified EVD fixation method that allows retraction of the EVD to reopen the drainage. We used this technique in patients requiring long-term EVD placement in the frontal horn who were expected to develop tightening of the ventricle.(More)
OBJECTIVE As the fixation of cranial bone flaps with titanium miniplates may produce esthetically objectionable bulges especially on the forehead covered with thin scalp, we developed a technique that solves this problem. PATIENTS AND METHODS The study material consisted of 19 consecutive sides treated by frontotemporal cranioplasty using free bone flaps(More)
Lumboperitoneal shunt placement requires access to the lumbar theca in the lateral position, followed by subsequent laparotomy in the supine position. This position change and repeat draping are bothersome, especially in heavy patients, so we developed a method that facilitates changing the patient position while keeping the surgical drapes in place. An(More)