Reversion-inducing cysteine-rich protein with Kazal motifs interferes with epidermal growth factor receptor signaling

金沢大学がん研究所The reversion-inducing cysteine-rich protein with Kazal motifs (RECK) gene had been isolated as an antagonist to RAS signaling; however, the mechanism of its action is not clear. In this study, the effect of loss of RECK function was assessed in various ways and cell systems. Successive cell cultivation of mouse embryonic fibroblasts (MEFs) according to 3T3 protocol revealed that the germline knockout of RECK confers accelerated cell proliferation and early escape from cellular senescence associated with downregulation of p19 Arf, Trp53 and p21Cdkn1a. In contrast, short hairpin RNA-mediated depletion of RECK induced irreversible growth arrest along with several features of the Arf, Trp53 and Cdkn1a-dependent cellular senescence. Within 2 days of RECK depletion, we observed a transient increase in protein kinase B (AKT) and extracellular signal-regulated kinase (ERK) phosphorylation associated with an upregulated expression of cyclin D1, p19Arf, Trp53, p21Cdkn1a and Sprouty 2. On further cultivation, RAS, AKT and ERK activities were then downregulated to a level lower than control, indicating that RECK depletion leads to a negative feedback to RAS signaling and subsequent cellular senescence. In addition, we observed that epidermal growth factor receptor (EGFR) activity was transiently upregulated by RECK depletion in MEFs, and continuously downregulated by RECK overexpression in colon cancer cells. These findings indicate that RECK is a novel modulator of EGFR signaling. © 2011 Macmillan Publishers Limited All rights reserved

Environment map generation in forest using field robot

We are developing an autonomous field robot to save labor in forest operation. About half of Japan\u27s artificial forest area is already available as wood. However, trees are not harvested and forest resources are not effectively used, because the labor and costs are not sufficient. The employment rate of young people in forestry tends to decline, and the unmanaged forest area is expected to increase in the future. Therefore, in our laboratory we propose an autonomous field robot with all terrain vehicles (ATV) that focuses on the automation of work. The robot we are developing automates weeding and observation for all trees in the forest. In this research, we introduced Robot Operating System (ROS) developed in recent years to this robot. In addition, we observed trees by generating an environmental map in the forest using Simultaneous Localization and Mapping (SLAM).Proceedings of International Symposium on Applied Science 2019 (ISAS),18-19 October, 2019, Ho Chi Minh City University of Technology, Ho Chi Minh City, Vietna

DSPを用いたDC-DCコンバータのロバスト制御に関する研究

The switching frequency of DC-DC conversion becomes higher as demands for downsizing andfast-response increase. At present, the switching frequency of an isolated DC-DC converter isabout 300kHz to 500kHz. PWM controllers are realized by using analog control ICs and someanalog parts. In recent years, the demands for more functions and capabilities are widelydiversified and sophisticated. To satisfy these demands, digitization of controllers has beenconsidered in academic and industrial worlds. In the practical use of DC-DC converters,characteristics of startup transient responses and dynamic load responses as well as output voltageresponses when the input voltage changing are of importance. Furthermore, in many applicationsof DC-DC converters, the loads and the input voltages cannot be specified in advance. Therefore,robust characteristics against loads and input voltage changes are necessary. Generally, the PIDcontrol is used for the digitization of the controller. The PID control is designed by trial and error,hence it is difficult to realize the robust characteristics. On the other hand, the H-infinity robustcontroller is of high-order, and its algorithm becomes too complex to implement. The robustcontroller with a simple algorithm is necessary for DC-DC converters.In this paper, an approximate 2-degree-of-freedom (2DOF) system is considered for controllers ofDC-DC converters. This system is obtained by constituting a model matching system and anapproximated inverse system and a first-order filter. The startup transient response is determinedby assigning dominant poles of model matching systems. The transfer characteristics from thedisturbance to the output are determined by one coefficient of first-order filter. Thus, the 2DOFsystem is approximately realized. This system has robust characteristics, which can be realized bya simple algorithm. When applying this approximate 2DOF controller to DC-DC converters, it isnecessary to improve the degree of approximation for stronger robustness. In this study, thecontrolled object is a forward converter whose switching frequency is 300kHz. We propose adesign method for improving the degree of approximation of both first-order and second-orderapproximate models. The approximate 2DOF digital controller is actually implemented on a DSPand is connected to the DC-DC converters. We make some simulations and experiments forexamining the startup transient responses and dynamic load responses as well as the output voltage responses when the input voltage changing. A good approximate 2DOF controller isobtained by placing the poles of the approximate 2DOF system so as not to approach the dominantpoles of model matching systems. It turns out that the characteristics are almost the same againstload changes and input voltage changes, and also that the experimental results are almost the sameas the simulation ones. The specifications are satisfied with the experiments and simulations. Thecontrol algorithm of the first order model is simpler than that of the second-order model. On theother hand, the second-order approximate model may improve the degree of approximation more.Therefore, the second-order approximate model may be used for the severer specifications.A higher switching frequency of DC-DC conversion is necessary so as to take fast-response andbetter robust characteristics. The resolution of digital PWM generators becomes lower as theswitching frequency becomes higher. Here exists an important problem of digitization ofcontrollers. Digital dither and delta-sigma modulation methods are proposed to improve thisproblem. These methods improve the resolution by averaging some switching periods. Therefore,low frequency ripples that are determined by a dither-pattern are superposed on the output voltage.The output voltage of the DC-DC converter must exist in a range of several percentage pointsincluding ripple noises, dynamic load responses, etc. Therefore, lower frequency ripples bydigitization should be as small as possible.In this study, the digital PWM resolution is improved by controlling the delay time of the PWMsignal. A delay time control system is realized by pulse-composite-circuits with two digital PWMgenerators. A method for determining control signals of two PWM generators is presented. It turnsout that the algorithm for designing both control signals are simple. The amplitude ofpulse-composite-circuits has a limit that is determined by the maximum duty cycle and switchingfrequency. In the case where the maximum duty cycle is 0.6 and the switching frequency is400kHz, the amplitude is obtained as 1/32. The relationship between the PWM resolution and theA-D converter resolution is examined. If the PWM resolution is lower than the A-D converterresolution, the output voltage oscillates in the shape of a limit cycle, and big noises occur. Whenthe pulse composition technique is applied to the DPWM generator built-in DSP, an experimentalmodel is designed and manufactured. It turns out that the PWM resolution is improved up to 1/32when the max duty cycle is 0.6 and the switching frequency is 400kHz, and that the limit cyclenoises disappear because the PWM resolution is higher than that of A-D resolution (10 bit).電気通信大学200

Modeling and Optimization of Impedance Balancing Technique for Common Mode Noise Attenuation in DC-DC Boost Converters

As an effective means of suppressing electromagnetic interference (EMI) noise, the impedance balancing technique has been adopted in the literature. By suppressing the noise source, this technique can theoretically reduce the noise to zero. Nevertheless, its effect is limited in practice and also suffers from noise spikes. Therefore, this paper introduces an accurate frequency modeling method to investigate the attenuation degree of noise source and redesign the impedance selection accordingly in order to improve the noise reduction capability. Based on a conventional boost converter, the common mode (CM) noise model was built by identifying the noise source and propagation paths at first. Then the noise source model was extracted through capturing the switching voltage waveform in time domain and then calculating its Fourier series in frequency domain. After that, the conventional boost converter was modified with the known impedance balancing techniques. This balanced circuit was analyzed with the introduced modeling method, and the equivalent noise source was precisely estimated by combining the noise spectra and impedance information. Furthermore, two optimized schemes with redesigned impedances were proposed to deal with the resonance problem. A hardware circuit was designed and built to experimentally validate the proposed concepts. The experimental results demonstrate the feasibility and effectiveness of the proposed schemes

Risk Factors for Early Mortality in Older Patients with Traumatic Cervical Spine Injuries—A Multicenter Retrospective Study of 1512 Cases

For older patients with decreased reserve function, traumatic cervical spine injuries frequently lead to early mortality. However, the prognostic factors for early mortality remain unclear. This study included patients aged ≥65 years and hospitalized for treatment of traumatic cervical spine injuries in 78 hospitals between 2010 and 2020. Early mortality was defined as death within 90 days after injury. We evaluated the relationship between early mortality and the following factors: age, sex, body mass index, history of drinking and smoking, injury mechanisms, presence of a cervical spine fracture and dislocation, cervical ossification of the posterior longitudinal ligament, diffuse idiopathic skeletal hyperostosis, American Spinal Injury Association Impairment Scale, concomitant injury, pre-existing comorbidities, steroid administration, and treatment plan. Overall, 1512 patients (mean age, 75.8 ± 6.9 years) were included in the study. The early mortality rate was 4.0%. Multivariate analysis identified older age (OR = 1.1, p p = 0.009), cervical spine fracture (OR = 4.2, p p p < 0.001) as risk factors for early mortality. Older age, male sex, cervical spine fracture, complete motor paralysis, and chronic kidney disease are prognostic factors for early mortality in older patients with traumatic cervical spine injuries