Youichi Katayama

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Measurement of multichannel continuous-wave near-infrared spectroscopy (CW-NIRS) is dependent on the modified Beer-Lambert law, which includes optical pathlength (PL) as an essential parameter. PLs are known to differ across different head regions and different individuals, but the distribution of PLs for the whole head has not been evaluated so far. Thus,(More)
Forceps manipulating robots have been developed for assisting surgeons to realize high-quality and precise operation in laparoscopic surgery. Currently several commercially available systems greatly contributed to operations. Still their large size causes problems in the operating theater, thus they need to be miniaturized. We developed a new compact(More)
Various studies have demonstrated the usefulness of near infrared spectroscopy (NIRS) for detecting cerebral ischemia during a carotid endarterectomy; however, it is difficult to apply NIRS to the diagnosis of ischemic stroke, since commercially available NIRS, which uses continuous-wave light, does not provide quantitative values of baseline hemoglobin(More)
Holmes’ tremor is an unusual combination of 2–5 Hz resting, postural, and kinetic tremors affecting the unilateral upper extremity, which is usually caused by stroke, trauma, vascular malformations, or tumors involving the midbrain [1]. Abnormal involuntary movements such as tremor affect the quality of life by interfering with simple motor tasks and daily(More)
The effects of artificial occlusal disharmony (AOD) on working memory function and prefrontal cortex (PFC) activity in the elderly were examined. We evaluated working memory function using the modified Sternberg test (ST). We measured activity in the bilateral PFC during ST using near-infrared spectroscopy (NIRS) before and after AOD: the mandibular(More)
This paper reports evaluation of compact forceps manipulator designed for assisting laparoscopic surgery. The manipulator consists of two miniaturized parts; friction wheel mechanism which rotates and translates forceps (62 x 52 x 150[mm3], 0.6 [kg]), and gimbals mechanism which provides pivoting motion of forceps around incision hole on the abdomen (135 x(More)
INTRODUCTION A T1map is required for some quantitative MR imaging applications. In dynamic contrast-enhanced (DCE) MRI, a T1map obtained before contrast agent administration allows us to convert image intensity into gadolinium concentration. Spoiled gradientrecalled echo (SPGR) sequence with variable flip angle (VFA) method has been widely used to construct(More)
CO2 ocean storage is proposed as a possible measure to mitigate climate changes caused by increasing atmospheric concentrations of the gas. The feasibility of the measure has been intensively investigated, yet its biological impact on marine animals is still largely unknown. We investigated the acute CO2 tolerance of juveniles of three marine invertebrates;(More)
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