The conventional body surface electrode of the electrocardiogram (ECG) is as much as two centimeters at most in diameter. It is known that the larger the area contacts the skin the greater cancellation of the local electromyogram (EMG) generated by the adjacent muscle fibers results in lesser noise contamination. On the other hand, a large area of the electrode is alleged to distort the ECG waveform. In this study, the effect of the area size of a body surface electrode was theoretically analyzed with a geometrical approach and we confirmed it empirically on ECG signals. The results elucidated that the size of the electrode was irrelevant to the accuracy of the waveform acquired with it. The biological potential acquired with a large sized electrode seems to be equivalent to that with a conventional electrode placed at the gravitational center of the large one, which is attribute to the unevenly distributed conductivity inside the body.
Pressure Ulcers are defined as ischematic tissue necrosis caused by pressure on the body for long duration, but its developing mechanism is not clarified. To prevent pressure ulcers, many kinds of antidecubitus mattresses have been developed, but it is practically prevented by postural change by care assistant. In this study, to clarify the formation mechanism of pressure ulcers, the mechanical simulation using finite element method (FEM) analysis was performed. Capillary deformation around the sacral bone was calculated using multiscale modeling method of FEM analysis. From the result, development of the prediction method of pressure ulcers based on biomechanical simulation was discussed. This method will make it possible to predict and prevent formation and development of pressure ulcers.
This paper addresses hardware designs of a half-centered locomotor central pattern generator (CPG), composed of units reproducing the electrical behavior of neurons and synapses, such as action potentials, bursting discharges, and post-synaptic potentials. The typical phenomenon generated by the CPG is an alternating rhythmic activity of extensor and flexor sites, in the absence of external rhythmic input. In order to reproduce the deletion phenomena, or the phase resetting and non-resetting rhythmic activities observed after during spontaneous cessation of activity, a two-level CPG network and unit burst generators (UBGs) were proposed by Rybak et al. (2006) from the viewpoint of mathematical modeling. The deletion at the first level, i.e., the rhythm generator (RG) level, caused the post-deletion rhythm to be phase shifted (reset) with respect to the pre-deletion rhythm. However, the deletion at the second level, i.e., the pattern formation (PF) level, caused the post-deletion rhythm to be un-phase shifted (non-reset) with respect to the pre-deletion rhythm. This paper confirms that such deletion phenomena, or the phase resetting and non-resetting phenomena, could be well reproduced in the hardware design of a two-level CPG using the electronic circuit simulator SPICE. In particular, it has been clarified that non-resetting deletions appeared, even with the cessation of activity occurring at any phase with respect to the observed temporal bursting. Hardware synapse models, phenomenologically reproducing excitatory and inhibitory post-synaptic potentials (EPSP and IPSP), were newly designed in order to connect the hardware neuron models, proposed by Hoshimiya et al. (1979) for the excitable and/or oscillatory neuron, and by Maeda and Makino (2000) for the bursting neuron.
In radiotherapy for lungs and livers, it is clinically important to concentrate its beam on the moving affected part in internal organs minimizing the irradiation to the healthy tissues. The method of irradiating the beam to the affected part synchronizing with the patient's respiration is widely recognized, where the indirect measurement of the marker displacement on the body surface is often used for its easy setup and measurement in real treatments. However, the irradiation accuracy is not enough when the respiratory status of the patients doesn't reflect the movement of internal organs accurately. In this paper, it has been studied how the movement of internal organs observed by 3D ultrasound image is related to the respiratory signal observed by the position sensitive camera. Firstly, it was evaluated based on the respiratory amplitude and respiratory phase, which made clear that there are some variances in the estimation of the internal organ's position from the respiratory signal in both cases. Secondly, the algorithm of DTW (Dynamic Time Warping) used by voice recognition has been applied to the respiratory wave form and the distance (amplitude difference) was calculated between the phase of each respiratory wave form and its average respiratory wave form. It was confirmed that the variance of the estimation of the internal organ's position from the respiratory signal was reduced from about 4.0 mm to 2.5 mm based on the phase matched by DTW.
Through learning, one can discriminate an object from similar distracters even if they are seen from different viewing angles. Previously, we have shown that the discrimination of images at several individual viewing angles produced immediate association across the views of the same object if the difference in the viewing angle was relatively small. To understand the underlying mechanism for the association of largely separated views, here we investigated how the association was influenced by the presentation of interpolated views. We found that the association learning was significantly enhanced if with the prior experience of interpolated views, and furthermore, showed that the establishment of such association was not due to the reinforced pairing, because reaction times were influenced by the amount of difference in viewing angles. The results suggest that the mechanism underlying the association of largely separated views is different from that for the views with relatively small difference.
This paper provides an easier and inexpensive method for fabricating flexible multichannel neural electrodes based on photosensitive material by using Micro Electro Mechanical System technologies. A conventional micromachining with non-photosensitive materials such as Poly (para-xylylene) (Parylene) or non-photosensitive polyimide includes a dry etching process. The dry etching process requires expensive machinery and maintenance cost, and involves complex multilevel processes for controlling etching conditions to define the outline of the neural electrodes and to expose the microelectrodes for detecting neural signals. Our method applying photosensitive material eliminates these costly and complex processes. This means that more options are allowed for optimizing the configuration and size of neural electrodes depending on experimental purposes, and electrodes could be fabricated at a lower cost with improved process yields. In this study, we used photosensitive polyimide, and designed and fabricated two types of flexible neural electrodes for recording an electrocorticogram or intracortical action potentials. The fabricated neural electrodes had physical properties (such as size and impedance) that were satisfactory for neural recordings. It was confirmed that the fabricated neural electrodes permit recording neural signals successfully from the rat's cerebral cortex.
Novel laser angioplasty with high ablation efficiency and low arterial wall injury is desirable. Recently, XeCl excimer laser coronary angioplasty (ELCA) has gained more attention for the treatment of serious stenosis by the formation of multiple plaques within the arteries. ELCA treatments achieve less thermal damages. However, dissections or perforations of coronary arteries limit its application. Mid-infrared laser with a wavelength of 5.75 μm is selectively well absorbed in C=O stretching vibration mode of ester bonds in cholesterol esters. The purpose of this study is to develop the novel laser angioplasty using the nanosecond pulsed laser with a wavelength of 5.75 μm for the safe atherosclerosis treatment. In this study, we used a mid-infrared tunable solid-state laser which is operated by difference-frequency generation (wavelength; 5.75 μm, pulse width; 5 ns, pulse duration; 10 Hz) as a treatment light source, and a thoracic aorta of WHHLMI rabbit as an atherosclerosis model. This study showed that nanosecond pulsed laser irradiations with a wavelength of 5.75 μm realized the selective and less-invasive treatment of atherosclerotic plaques.
Functional near-infrared spectroscopy (fNIRS) is a new brain imaging technology that has great potential to the easy measuring method as compared with fMRI and PET. However fNIRS measurements require an annoying task to fix many optical fibers on a subject's head. Each optical fiber must be fixed on the skin directly so as to not overlap with hair because the hair interferes with the near-infrared light and will decrease the signal to noise ratio. This study developed an automatic hair mover to reduce the cost of fixing optical fibers.