Medical ultrasound equipment is widely used in many fields of clinical medicine since ultrasound technology has the advantage of being non-invasive, easy-to-use, real-time, in addition, it can provide various types of information for morphological, functional and tissue characteristic diagnosis. From now on, home-care medicine will become more important for the healthy longevity society, and medical ultrasound technology will be utilized for precise and easy point-of-care diagnosis. Here, I give an outline of the latest technologies of medical ultrasound.
We have developed the method for improvement in the receiver dynamic range and signal processing technique of image reconstruction in demodulated direct current voltage-based microwave CT (DC-MCT). By using standard signal generator with the low phase noise and phase synchronization of signal source, the reconstructed amplitude- and phase-images were obtained. Improvement in receiver dynamic range was attempted on the distributed system gains to radio- and low-frequencies. By removing unwanted components of the received signal, the receiver dynamic range was expanded. Two methods for removing unwanted components from the received signal were attempted by using time domain filters to remove all receiver noises from the measurement data. By removing unwanted components, the reconstructed definite tumor images of the breast-and biological-phantoms were obtained. At the result, this paper shows usefulness of the new method that improves the receiver dynamic range and reconstructed images.
It is known that very low frequency of R-R interval (RRI) is induced by the autonomic nervous system, and it is useful to evaluate the property of autonomic control of heart. Therefore, in this study, we analyze long term heartbeat fluctuations of spinal cord injury patients with fractal analysis to evaluate their fractal properties of autonomic nervous system. First, fractal property is obtained using Detrended Fluctuation Analysis. As a result, we find that spinal cord injury subjects have the same correlated volatility of healthy subjects. Second, we apply space-scale correlation using wavelet to their heart rate variability of RRI to quantify local fractal property including cascade structure. In the result, it is found that correlation of spinal cord injury patients is significantly higher than that of healthy subjects. These results present that the differences of circular dynamic state between spinal cord injury subjects and healthy subjects are not observed in the global fractal properties but in the heteroscedasticity.
We have reported that frequency domain interferometry (FDI) imaging with the Capon method has the potential to acquire high range-resolution ultrasound images. The reported method employed uniform frequency averaging to suppress coherent interferences. In atmospheric radar imaging, adaptive averaging has proposed to perfectly suppress coherent interference. In the present study, we applied adaptive frequency averaging to the FDI imaging method and investigated its image quality in a simulation study, where the -6dB bandwidth of the echo returned from an interface was 2.6MHz. When two targets 0.1mm apart from each other were located in a region of interest the FDI imaging method using uniform frequency averaging succeeded in estimating the interface ranges correctly; however, the estimated echo intensity was 6.3dB lower than the true echo intensity. In contrast, the FDI imaging method using adaptive frequency averaging successfully estimated the interface ranges, and the estimated echo intensity was only 0.049dB higher than the true one. These results indicate that the FDI imaging method using adaptive frequency averaging has excellent accuracy in the measurement of echo intensity, under the condition that the echo waveform returned from each target is the same as the waveform of the reference signal.
A few studies report on the swaying motion of the body in the sitting position; however, these studies have not evaluated the motion sickness induced by watching movies, taking conveyance, and others. This study aimed to analyze the stabilograms recorded while an individual was in the sitting position. This study included 7 healthy male subjects (age, 21-22 years). Stabilometry was performed in the sitting position 5 min before, 5, 10, ..., and 60 min after the alcoholic load; the alcoholic load causes a decrease in the cerebellar equilibrium function controlling the vestibulospinal reflex. Degree of suppression of the equilibrium function can be simulatively adjusted in proportion to the alcoholic intake. We analyzed the following parameters of the stabilograms of these subjects: the area of sway, total locus length, total locus length per unit area, and our proposed indices. We found that the significant changes of these sway values, caused by alcohol intake, in the sitting position were similar to those in the standing position.
The corticothalamic Compact Model with time delay proposed by Kim and Robinson is successfully reduced to a real Ginzburg-Landau equation in the vicinity of pitchfork bifurcation point, using center manifold theory for functional differential equations and perturbation theory of week interactions. Broad agreement between the predictions with the reduced equation and corresponding numerical results with the original equation are confirmed in transient analysis of single-body and two-body problem, with emphasis that a “projection to the center subspace” is essential. Furthermore, analogies with Ginzburg-Landau theory of phase transition and with theory developed by Benayoun et al. of neural avalanches are pointed out.
The motion of pronation and supination of the forearm is one of findings of soft neurological signs. Soft neurological signs used as diagnosis methods of a developmental disability. The motion of pronation and supination of the forearm is movement to bend elbow to 90 degrees, and to rotate the palm and the back of the hand. When doctor checks this motion, he observes a patient's regularity and dexterity. But there are problems. The one by doctor's personal subjectivity is large, because the evaluation between doctors isn't equable. It is hoped that a more objective and simple evaluation method is established. We developed evaluation system of a motion of pronation and supination of a forearm using three-dimensional wireless acceleration and angular velocity sensors. Our developed evaluation system is a simple and easy system. We think that this system have the potential to be used as the evaluation system for a developmental disability. This paper deals with a examination and details of indices for evaluating a motion of pronation and supination.
Recently, a lot of research using multi-neuron recording has been done, however, there are many problems with extracting the features from obtained spike time series which is huge amount and complex. Here we introduce a new method to estimate synaptic connection strengths between neurons by fitting for Izhikevich model using maximum likelihood estimation. We demonstrate that our method is able to estimate connection strengths from spike time series given by simulated neural ensemble and able to estimate non-connectivity between two independent cultured neuronal networks. These results suggest that our method can apply for network and plasticity analysis of neuronal networks.
The number of dialysis patients is approximately 300,000 and is increasing every year in Japan. A renal failure patient requires a hemodialysis shunt for dialysis to be performed; however, the blood vessels around the hemodialysis shunt may become stenosed. The stethoscope auscultation of vascular murmurs has some use in the assessment of access patency; however, this diagnostic approach is skill dependent. Therefore, a diagnostic support system to detect stenosis is desirable. We developed an auscultating diagnosis support system for assessing hemodialysis shunt stenosis by using a self-organizing map (SOM) and short-time maximum entropy method. In this paper, for the purpose of improving the accuracy of stenosis detection, the Mel-frequency cepstrum coefficient (MFCC)-based hidden Markov model (HMM) was also used. As a result, a high correlation between an SOM system and HMM system was found. Therefore, the credibility of the each system was confirmed. Furthermore, the results indicated that the accuracy of stenosis detection could be improved by combining the SOM and HMM methods.
In this study, a high separation ratio micro-fluidic cell sorting by dielectrophoretic (DEP) force is presented. Resent development of iPS cell technology has promoted the possibility of regenerative therapy. In technologies of genetic cell processing requires purification of specific target cells by cell sorter. Most prevailing system for cell separation is the flow cytometry (FCM), which has been developed for research purpose. In spite of the high performance in separation ratio, it takes rather high cost in one operation. For clinical use, a device contacting biological specimen must be disposable to prevent cross infection. A low cost micro-fluidic cell sorter, using DEP force, can be fabricated by photolithography technique. However, sorting rate of existing DEP cell sorter is far lower than that of FCM because of the limitation of applicable voltage in aqueous fluid. To circumvent the problem and raise the DEP force, implementation of field gradient dependence was investigated. The design of flow channel was deiced to make high gradient at the separation point, and enhance the DEP force. Distribution of the electric field was proved to have a peak intensity at the entrance of separation channel by numerical calculated of Finite Element Method. DEP separation of 2μm diameter latex beads at the rate of 3.0mm/sec, 6 times large than that of our previous system, was demonstrated.
Tumor hypoxia is considered a potential therapeutic problem because it reduces the effects of radiation therapy. Clinical experience has shown that long-term tumor oxygenation cannot be achieved with oxygen inhalation, but the mechanisms behind this phenomenon remain unknown. In this study, we designed an optical system for evaluating spatiotemporal changes in tissue oxygen tension (pO2) by phosphorescence quenching. The system can measure continuous changes in pO2 at a fixed point and can also perform two-dimensional mapping of pO2 in any part of the tumor tissue. We implanted tumor tissue in a dorsal skinfold chamber of C57BL/6 mice and observed tumor growth. The mice received oxygen inhalation and pO2 was measured. Tumor pO2 increased after inhalation but the oxygen level was not maintained despite continuous inhalation of pure oxygen; the tumor returned to a hypoxic state. These results mimic the clinical experience of oxygen inhalation treatment in radiation therapy. Our system reproduces the repeat hypoxic phenomenon in a murine tumor model and can be used to determine the mechanisms of oxygen metabolism in tumors.
In the auditory cortex, auditory-evoked onset activities have been extensively investigated as a cortical representation of sound information and emotional information associated with the sound. Yet, less attention has been paid to date to steady-state activities following the onset activities. In this study, we used machine learning to investigate whether steady-state neural activities in the presence of continuous sounds represent the sound frequency and emotion associated with the sound. A microelectrode array with a grid of 96 sites recorded local field potentials (LFPs) in the 4th layer of the auditory cortex of anesthetized rats and Sparse Logistic Regression (SLR) decoded the sound frequency from steady-state neural activities of LFPs. Band-specific powers at every recording sites and phase locking values between every pair of recording sites served as input vectors of SLR. We also investigated how these decoding accuracies depended on either aversive or appetitive auditory classical conditioning. Consequently, we found that SLR were able to decode the sound frequency from steady-state neural activities as well as onset activities and that the decoding accuracy at some particular bands significantly either improved or worsened in conditioning-dependent manners. These results demonstrate that the steady-state neural activities contain rich information about not only test sounds but also emotions associated with the sounds.
In target tracking problem, we can use multiple sensor to improve accuracy of the system. However, measurements from various sources are sometimes delayed and come at different rates. These measurements are known as out of sequence measurements (OOSMs). In other researches, Extended Kalman Filter (EKF), Particle Filter (PF) and Ensemble Kalman Filter (EnKF) provide us good solutions to OOSM problems. A solution via EKF is fast but cannot be applied to strong nonlinear systems. On the other hand, although PF is applicable to nonlinear system, the computational cost is so high that it is difficult to apply to real applications. In this paper, we propose techniques to solve OOSM problem using EnKF whose properties lay between EKF and PF. It is applicable to strong nonlinear system, requires less computation than PF. At the end of this paper, we investigate the performance of the solution via EnKF comparing to others. The results show competitive performance and attractiveness of solving OOSM via EnKF.
Generalized Minimum Variance Control (GMVC) is one of the predictive control method for the time delay system. Most of the GMVC are designed for a Single-Input Single-Output (SISO) system. However, there are a lot of Multi-Inputs Multi-Outputs (MIMO) systems, such as the chemical plants, which have the multiple time delays of different length in regard of inputs and outputs pair. As a result, there is a problem that the response time still mutual interference. This paper proposes two new techniques for the MIMO system with the multiple time delays. The first is GMVC with a Cross-Controller method. The second is GMVC with the skeletal matrix. Comparing the two methods, we demonstrate the advantages of the matrix skeleton. Also, the closed-loop system is structured of Continuous-Time GMVC (CGMVC).
Lighting occupies not less than 30% of electrical power consumption in a typical office building. Lighting control systems have been proposed as energy-saving to reduce electrical power consumption of lighting by supplying necessary illuminance for necessary locations, combined with illuminance sensors and human presence sensors. However, in the closed-loop control of dimming, abrupt changes of target illuminance by information from human-presence sensors might cause flicker of illuminance, and might thereby decrease the office workers' comfort and productivity. This paper proposes a direct-solution algorithm of an inverse problem for open-loop control of lighting to reduce flicker of illuminance. The proposed algorithm computes the setting pattern of the dimming rate from the target illumination distribution on desks using a light influence matrix derived by the point-by-point method of lighting. In this study, we applied a lighting group control system that adopts this proposed method in an actual office. In this paper, we show that the proposed method is effective by experiments using this system.
This paper presents a way to acquire effective rule-sets for realizing the suitable distribution of cruising taxicabs based on a decentralized autonomous manner. As a result of the revision of Road Transportation Law, a taxi business have been saturated by new entries, and rookie drivers particularly have a lot of difficulty in finding passengers, because of the lack of the knowledge or experiences. Here, it is desired and effective for less-experienced drivers to design a support system which suggests potential destinations for finding passengers. As for the problem of distributing cruising taxicabs, there are many uncertainties caused by incomplete observations, e.g. locations of passengers as well as other taxicabs. Due to these uncertainties, it is impossible to distribute taxicabs optimally, e.g., by a certain centralized control. This paper proposes a decentralized and autonomous framework for distributing cruising taxicabs by adopting priority-based rules, which calculate the priorities of areas, which are to be adjusted according to the situations of each taxicab. Through some computational simulations, the effectiveness and the potential of the proposed method are confirmed.
This paper proposes a new optimizing system for improved recognition of facial expressions based on a feature extraction filter which uses genetic programming (GP), Haar-like features and neural networks (NN). The purpose of the system is to gather data useful for the recognition of facial expressions using GP and Haar-like features and to evaluate this data's validity. The system employs a technique which converts images of facial expressions into feature images using Haar-like features, then extracts features from these converted images using GP. GP creates individuals using the feature-extracting filter and optimizes them. NN then classifies these facial expressions. The classification rate for the final generation of images was 0.88 for neutral faces, 0.6 for pleasure, 0.6 for sadness, 0.72 for surprise, 0.8 for anger, 0.6 for disgust and 0.44 for fear. The reason for the low classification rate for fear was that high fitness individuals could not be obtained. In addition, the system encountered difficulties in distinguishing images with very similar expressions, such as fear and disgust. On the other hand, compared to the previous system, the processing speed of the new system was markedly quicker. This new approach enables basic experiments to be repeated in a short-term cycle and makes it possible to search for important factors, thus realizing the full potential of the system. A number of practical applications for the system can be expected based on this new approach.
Voice activity detection (VAD) is an essential technique to develop a sophisticated voice interface. However, VAD with sufficient detection capability has not been presented yet. In particular, it is difficult that the beginning and ending of a word are accurately detected in noisy environments. In this paper, we describe extended models with multi-condition training (extended MC-models) for misdetection and evaluate their noise robustness by a large amount of word recognition simulations. From the results of the simulations, simple whole-word models degraded recognition performance when input speech signal was accompanied by non-speech segments, whereas the extended MC-models maintained the performance. Furthermore, in consideration of practical applications, we carried out the simulations combining CENSREC-1-C baseline VAD with the extended MC-models. The results also showed the usefulness of the extended MC-models under 20 and 10dB signal-to-noise ratio conditions.
In this paper, we propose the sharing method that shares a memory between some physical link by using the multi port memory in wormhole router for NoC (Network on Chip) as efficient usage of the flit buffers. If the proposed method is implemented by conventional method, hardware cost increase greatly. Therefore, we implement proposed method by using a methods that a memory is shared by block size. In this paper, we show the effectivity of proposed method by simple estimation of hardware cost and evaluation of communication performance by software simulation.
We have developed a root cause analysis system for enterprise IT system environment. In this paper, we propose a rule construction method which builds the analysis rule data object from the general analysis rules and the topology information of the actual target IT environment. By this method, IT administrator can use RCA system without any manual rule modifications. Regarding execution of analysis, we introduce the certainty factor to realize a robust analysis when the ordinarily and reachability of fault event can not be guaranteed.
In the distributed search system, the method of mapping and managing documents on segmented indexes is significant to realize load balancing of distributed search process and efficient cluster reconfiguration. Consistent hashing is the advanced method of data mapping which minimizes the network traffic and redundant index data processing in the index reconfiguration. However, if the cluster consists of several thousands of nodes, it requires huge memory resources. Furthermore, it takes a long time to execute the index reconfiguration because of the overhead of many index splitting processes. In this paper, we propose a new method called slot-based virtual node method of consistent hashing to solve the above issues. As the multiple nodes are added or removed, our new method plots or reallocates the virtual nodes on the hash ring space to realize “a bunch of” data migration as far as possible to optimize the index reconfiguration. Slot-based virtual node management saves memory consumption for the mapping information. We actually evaluate memory consumptions of both conventional and our proposed methods to bring out the resource-saving effect. Besides, we estimate lapse times of index reconfiguration processes based on the data processing models to verify the effective reduction of time in our method.
Recent advances in computer design allow microprocessors to enable parallelism in programs in order to achieve high performance. True dependency is one of the many factors that restrict parallelism in a computer program. To overcome the restrictions of true dependency, a number of schemes for value prediction have been proposed. The value predictor predicts an instruction result on the basis of the value history obtained from Value History Table (VHT). However, it consumes considerable energy because VHT is large and is referenced very frequently. In this paper, we propose a more efficient mechanism for a value predictor that extends the use of an existing branch target buffer (BTB) to reduce the number of invalid VHT references. We introduced a predictability bit (p_bit) to identify an instruction that has a predictable value, and we added a field to BTB to ensure that the p-bits corresponded to successive instructions. The proposed mechanism controls VHT references on the basis of p_bits. The evaluation results show that the proposed mechanism reduces invalid references by 27.6% and 42.4% and energy by 16.6% and 25.7% with 0.1% performance loss on average in the 8 and 32 p_bits length, respectively.
In this research we apply Markov decision processes with unknown parameters to maintenance problem. We propose a new maintenance method which maximizes total reward with reference to a Bayes criterion.