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IntroductionWe newly designed and developed two types of hydrogen fuel cell (HFC) buses (motorcoach type and minibus type) with a mobile laboratory system. Feasibility studies have been performed for mobile laboratory testing, especially for the laboratory performance of COVID-19 RT-PCR (PCR).MethodsWe evaluated the driving range capability, PCR sample size capacity, turn-around time (TAT), and analytical performance for the detection of SARS-CoV-2. Saliva samples were used for the current research and the analytical performance was compared with reference PCR.ResultsThe estimated driving range and sample size capacity were 432 km and 3,258 samples, respectively for the HFC motorcoach and 313 km and 2,146 samples for the HFC minibus, respectively. For the TAT, the median time between the sample submission and the completion of PCR were 86 min for the motorcoach and 76 min for the minibus, and the median time between sample submission and the electronic reporting of the result to each visitor were 182 min for the motorcoach and 194 min for the minibus. A secondary analysis of 1,574 HFC mobile laboratory testing samples was conducted and all negative samples were negative by reference PCR. Furthermore, all positive samples were confirmed as positive by reference PCR or other molecular examinations.ConclusionWe confirmed the feasibility of HFC mobile laboratory systems for achieving the rapid reporting of highly accurate PCR results.

Recently, the maintenance and management of infrastructure, such as paved roads and bridges, at a low cost has become important. Although some measurement methods including the falling weight deflectometer test have been developed to assess the soundness of paved roads, it is difficult to measure the data in a constant manner, for instance, on a daily basis. Therefore, we present an approach as per which we install vibration sensors on paved roads and automatically detect the deterioration of the paved roads via the installed vibration sensor and a machine-learning technique.Deterioration detection techniques that exploit vibration sensors have been studied; however, those were limited to bridge monitoring. No studies for the vibration measurement of paved roads using fixed sensors have been conducted. Herein, we focus on the deterioration of paved roads, specifically, in the form of road cracks, and conduct vibration measurements that highlight the differences in the vibrations of roads with and without cracks.In this paper, we describe the vibration measurements of a paved road with and without cracks and propose a framework for detecting cracks. An anomaly detection technique is necessary for using our detection framework. In this paper, we also evaluate the detection performance using anomaly detection techniques—namely, one-class support vector machine, isolation forest, and local outlier factor—using the measured vibration data.

To clarify the status of macrolide and fluoroquinolone resistance of clinical strains of Mycoplasma genitalium in Japan, we amplified portions of the gyrA, parC, and 23S rRNA genes from DNAs in 627 first-voided urine specimens collected from men with M. genitalium-positive urethritis who visited clinics mainly in Sendai, Tokyo, and Osaka, Japan, from 2013 to 2017, by PCR and sequenced. The incidence of single amino acid changes at Met95 or Asp99 in GyrA increased chronologically and was approximately 10% from 2015 onward. The incidence of amino acid changes at Ser83 or Asp87 in ParC was approximately 50% in 2013 but increased to 60–70% from 2014 to 2017. The incidence of mutations at A2071 or A2072 in the 23S rRNA gene increased chronologically and reached over 70% in 2017. The prevalence of M. genitalium harboring alterations in ParC and mutations in the 23S rRNA gene increased and was approximately 50% in 2016 and 2017. The prevalence of M. genitalium with alterations in both GyrA and ParC and mutations in the 23S rRNA gene, which could be associated with treatment failures with the sitafloxacin and azithromycin regimens, were approximately 15% and 10% in 2016 and 2017, respectively. The prevalence of M. genitalium with genetic alterations associated with resistance to fluoroquinolones and/or macrolides is increasing rapidly in Japan. We must prevent the further selection of multi-drug-resistant M. genitalium so that M. genitalium infections will not become untreatable.

MIMO (Multiple-Input Multiple-Output) technologies have attracted much interest for high-rate and high-capacity wireless communications. MIMO technologies under frequency-selective fading environments (wideband MIMO technologies) have also been studied. A wideband MIMO system is affected by ISI (Inter Symbol Interference) and CCI (Co-Channel Interference). Hence, we need a MIMO signal detection technique that simultaneously suppresses ISI and CCI. The OFDM system and SC-FDE (Single Carrier-Frequency Domain Equalization) techniques are often used for suppressing ISI. By employing these techniques with the ZF (Zero Forcing) or the MMSE (Minimum Mean Square Error) spatial filtering technique, we can cancel both ISI and CCI. To use ZF or MMSE, we need channel state information for calculating the receive weights. Although an LS (Least Square) channel estimation technique has been proposed for MIMO-OFDM systems, it needs a large estimation matrix at the receiver side to obtain sufficient estimation performance in heavy multipath environments. However, the use of a large matrix increases computational complexity and the circuit size. We use frequency domain channel estimation to solve these problems and propose an iterative method for achieving better estimation performance. In this paper, we assume the use of a MIMO-UWB system that employs a UWB-IR (Ultra-Wideband Impulse Radio) scheme with the FDE technique as the wideband wireless transmission scheme for heavy multipath environments, and we evaluate the iterative frequency domain channel estimation through computer simulations and computational complexity calculations.

Recently, hybrid vehicles (HVs) have become widespread. In the current HVs, a high-voltage (200 V) battery supplies power to the Power Control Unit (PCU) for driving a motor, generator and air conditioner compressor. It is expected that such kinds of power electronic devices will increase in number in the future. We previously proposed a power line communication (PLC) that uses a high-voltage power line. In this paper, we present the development of a high-voltage PLC system that can simultaneously control multiple power electronic devices in real time and demonstrate the system operation. First, in a system of a commercially available HV, the results of transmission characteristics and electromagnetic noise characteristics that are superimposed on the high-voltage power line are shown. Then the bit error rate (BER) performance under the above noise environment is clarified by computer simulations. Finally, we construct a prototype of the high-voltage PLC system and demonstrate that the system can simultaneously control the rotational speed of two motors.

Mainly, a uniform linear array (ULA) has been used for DOA estimation of coherent signals because we can apply the spatial smoothing preprocessing (SSP) technique. However, estimation by a ULA has ambiguity due to the symmetry, and the estimation accuracy depends on the DOA. Although these problems can be solved by using a uniform circular array (UCA), we cannot estimate the DOA of coherent signals because the SSP technique cannot be applied directly to the UCA. In this paper, we propose to estimate 2-dimensional DOA (polar angles and azimuth angles) estimation of coherent signals using a cylindrical array which is composed of stacked UCAs.

We developed a PCR-based assay involving Invader® technology for detection of the genital mycoplasmas of Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum. We compared its performance with that of a PCR-microtiter plate hybridization assay, which we developed previously, in detecting genital mycoplasmas in first-voided urine (FVU) specimens from men with non-gonococcal urethritis. The tests targeting each of the genital mycoplasmas were specific for the respective species and could detect as few as 10 copies of the plasmids containing the target genes of each of the genital mycoplasmas per reaction. The assay using the InvaderPlus® method (InvaderPlus® assay) showed very similar performance to that of the PCR-microtiter plate hybridization assay for detecting the genital mycoplasmas in the FVU specimens. In addition, the PCR and endonuclease reaction in the InvaderPlus® assay were carried out simultaneously in one procedure, thus simplifying the assay, leading to time- and labor-savings and a decrease in the risk of specimen contamination. The InvaderPlus® assay could be useful in diagnosing genitourinary tract infections caused by the genital mycoplasmas.

The artificially generated noise from the appliances has a periodicity in frequency domain. A noise suppression system, which is based on the PI(Power Inversion) algorithm and using frequency shift, has already been proposed. However, the system has a significant problem that the suppression effect can not be obtained when the frequency shift is not accurate. In this paper, reduction method of frequency shift error is proposed. Numerical results show that frequency shift error is reduced by the proposed method when the number of snapshots and the interval of sampling are set appropriately.

Objectives We determined the prevalence of macrolide and fluoroquinolone resistance-associated mutations in Mycoplasma genitalium DNA specimens from men with non-gonococcal urethritis (NGU) and analysed their effects on antibiotic treatments of M. genitalium infections. Methods In this retrospective study, we examined antibiotic resistance-associated mutations in the 23S rRNA, gyrA and parC genes of M. genitalium and the association of the mutations with microbiological outcomes of antibiotic treatments in men with M. genitalium-positive NGU. Results No macrolide resistance-associated mutations in the 23S rRNA gene were observed in 27 M. genitalium DNA specimens in 2011 and in 24 in 2012. However, 5 of 17 in 2013 had 23S rRNA mutations. Three of 15 in 2011, 6 of 19 in 2012 and 8 of 17 in 2013 had fluoroquinolone resistance-associated alterations in ParC. Three in 2013 had both the antibiotic resistance-associated alterations coincidentally. In two men with M. genitalium harbouring 23S rRNA mutations, the mycoplasma persisted after treatment with a regimen of 2 g of extended-release azithromycin (AZM-SR) once daily for 1 day. All nine men with mycoplasma harbouring ParC alterations were microbiologically cured with a regimen of 100 mg of sitafloxacin twice daily for 7 days. Conclusions Macrolide- or fluoroquinolone-resistant M. genitalium appears to be increasing, and the increase in fluoroquinolone-resistant mycoplasmas is especially remarkable in Japan. Mycoplasmas harbouring 23S rRNA mutations would be resistant to the AZM-SR regimen, but those harbouring ParC alterations would still be susceptible to the sitafloxacin regimen.

The noise-related phenomenon, stochastic resonance (SR), may improve the performance of signal detection devices. In digital signal processing, the effect of SR depends on the observation time and sampling frequency. To apply it to digital signal processing, these two parameters must be determined. This paper investigates the observation time and sampling frequency for efficient SR in a digital system.

Efficient detection of a weak signal in a noisy environment is one of the most intensely studied topics in signal processing. In such research, the concept of a noise-induced giant response, such as occurs in stochastic resonance, has attracted a great deal of attention. In the present study, by analyzing a system subjected to a deterministic fluctuation, we show that the occurrence of a giant response is strongly related to instability in the system. We derive the response function of the system, and obtain its eigenfunctions which determine the response behavior of the system. We find that the maximum eigenvalue of the response function diverges when instability arises in the system, and the infinite eigenvalue gives rise to a giant response. Our approach is analogous to the well-established fluctuation-response theory, and can be easily extended to a system with purely stochastic fluctuations.

An inter-vehicle communication system is highly advantageous for driving safety support systems, such as collision avoidance systems at intersections. In an inter-vehicle communication system, a channel-tracking scheme is essential to achieve reliable wireless communication under the fast fading environment caused by surrounding vehicles. For coherent detection, decision feedback is a well-known channel-tracking scheme. In this scheme, replica signals are generated and channel estimation is performed by using the replica signals. However, because channel estimation performance depends on the signal-to-noise (SNR) at symbol time, decision feedback errors occur by the lower SNR caused by fast fading. The feedback errors degrade the transmission performance significantly. In an orthogonal frequency division multiplexing (OFDM) system, the time domain 0-padding scheme is a well-known channel estimation technique. Although better channel tracking performance is expected by applying the 0-padding scheme, the tracking performance is degraded when employing guard-bands in the OFDM system. In this paper, we propose an improved time domain 0-padding scheme for an STBC-OFDM system employing guard-bands based on the IEEE802.11p standard for inter-vehicle communication, and show the improved performance through computer simulations.

The UWB-IR (ultra wideband-impulse radio) technology and MIMO system have attracted interest for next generation high rate radio communications. The authors researched IMO-UWB systems using the FDE (frequency domain equalization) technique with the MMSE spatial filtering technique. The UWB system will be used in short range wireless transmissions. Then, we usually have line-of-sight (LOS) environments in the MIMO-UWB systems. The authors conducted propagation measurement and evaluated the transmission performance of MIMO-UWB systems in LOS environments. Then, the authors proposed a timing control scheme for performance improvement. SIC (successive interference canceller) and PIC (parallel interference canceller) are known as better signal separation techniques in MIMO systems. In these techniques, the authors obtain diversity gain subtracting the data detected by a spatial filtering technique from the received signal. Therefore, we can achieve better signal separation performance by the diversity gain. The authors found that the timing control scheme is also needed for the SIC and PIC techniques in LOS MIMO-UWB environments by bit error rate (BER) evaluation. In this paper, the authors show the signal separation performance applying the SIC and PIC techniques with the timing control scheme in LOS environments.

The phenomenon whereby the response to a weak low-frequency input signal is maximized in an oscillatory system with additional high-frequency input signals of appropriate amplitude is known as vibrational resonance (VR). In this study, the occurrence of VR in over-damped systems is analytically and numerically explained in the framework of linear response theory. The origin of the large response of VR is shown to be the dynamical bifurcation caused by tuning the input signals.