Hiroyuki Hagiwara

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Nineteen-hour variation of postural sway, alertness and rectal temperature during sleep deprivation were studied. Alertness decreased gradually at night and remained low until morning. Postural sway in the eyes-closed condition increased during early morning. In six of the eight subjects the greatest sway was observed during the 3-h period when rectal(More)
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)
Nineteen-hour variation of subjective sleepiness, performance and physiological indices were assessed during sleep deprivation. Longitudinal data of each index had its characteristic curve through which the values changed from day level to night level. A comparison of the time when each curve crossed its mid-range (50% value of its range) showed that those(More)
This article presents an alertness evaluation method being analyzed by the authors, and discusses its application. With the aim of quantifying the physiological activity of the living body, the alpha-attenuation test (AAT) for evaluation of alertness was assessed. AAT is a method of quantitatively determining alertness level from alpha-wave power spectra(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)
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)
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)