376 research outputs found

    Stretch reflex improves rolling stability during hopping of a decerebrate system

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    When humans hop, attitude recovery can be observed in both the sagittal and frontal planes. While it is agreed that the brain plays an important role in leg placement, the role of low-level feedback (the stretch reflex) on frontal plane stabilization remains unclear. Seeking to better understand the contribution of the soleus stretch reflex to rolling stability, we performed experiments on a biomimetic humanoid hopping robot. Various reflex responses to touching the floor, ranging from no response to long muscle activations, were examined, and the effect of a delay upon touching the floor was also examined. We found that the stretch reflex brought the system closer to stable, straight hopping. The presence of a delay did not affect the results; both the cases with and without a delay outperformed the case without a reflex response. The results of this study highlight the importance of low-level control in locomotion for which body stabilization does not require higher-level signals.This is the accepted manuscript. The final version is available at http://iopscience.iop.org/article/10.1088/1748-3190/10/1/016008/meta;jsessionid=8394D6E9724906C836DC3624B5BF2F90.c1

    Investigation of radon and thoron concentrations in a landmark skyscraper in Tokyo

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    The temporal variation of the radon concentration, and the radon and thoron concentrations every three months for a year were measured using two types of devices in a landmark skyscraper, the Tokyo Metropolitan Government Daiichi Building. In the measurement of temporal variation of the radon concentration using a pulse type ionization chamber, the average radon concentration was 21 ± 13 Bq m-3 (2 - 68 Bq m-3). The measured indoor radon concentration had a strong relationship with the operation of the mechanical ventilation system and the activities of the office workers. The radon concentration also increased together with temperature. Other environmentalparameters, such as air pressure and relative humidity, were not related to the radon concentration. In the long-term measurements using a passive radon and thoron discriminative monitor, no seasonal variation was observed. The annual average concentrations of radon and thoron were 16 ± 8 Bq m-3 and 16 ± 7 Bq m-3, respectively. There was also no relationship between the two concentrations. The annual average effective dose for office workers in this skyscraper was estimated to be 0.08 mSv y-1 for 2000 working hours per year. When considering the indoor radon exposure received from their residential dwellings using the annual mean radon concentration indoors in Japan (15.5 Bq m-3), the annual average effective dose was estimated to be 0.37 mSv y-1. This value was 31 % of the worldwide average annual effective dose

    Changes of ambient gamma-ray dose rate in Katsushika Ward, metropolitan Tokyo before and after the Fukushima Daiichi Nuclear Power Plant Accident

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    Katsushika Ward in the eastern part of metropolitan Tokyo was the Tokyo area with the highest deposition of artificial radionuclides after the nuclear accident at the Fukushima Daiichi Nuclear Power Plant. A car-borne survey of the air kerma rate was conducted for all of the ward and the results were compared with measurements done in 2005. The mean air kerma rate in 2014 was 59 ± 12 nGy h⁻¹ and that was 50% higher than the rate in 2005 (p < 0.01). Additionally, the environmental half-life was estimated to be 1.9 years from the transition of ambient equivalent dose rate after the accident for data published by the Katsushika Ward Office

    Diagnosis and Prognostication of Ductal Adenocarcinomas of the Pancreas Based on Genome-Wide DNA Methylation Profiling by Bacterial Artificial Chromosome Array-Based Methylated CpG Island Amplification

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    To establish diagnostic criteria for ductal adenocarcinomas of the pancreas (PCs), bacterial artificial chromosome (BAC) array-based methylated CpG island amplification was performed using 139 tissue samples. Twelve BAC clones, for which DNA methylation status was able to discriminate cancerous tissue (T) from noncancerous pancreatic tissue in the learning cohort with a specificity of 100%, were identified. Using criteria that combined the 12 BAC clones, T-samples were diagnosed as cancers with 100% sensitivity and specificity in both the learning and validation cohorts. DNA methylation status on 11 of the BAC clones, which was able to discriminate patients showing early relapse from those with no relapse in the learning cohort with 100% specificity, was correlated with the recurrence-free and overall survival rates in the validation cohort and was an independent prognostic factor by multivariate analysis. Genome-wide DNA methylation profiling may provide optimal diagnostic markers and prognostic indicators for patients with PCs

    Natural Course of Pachychoroid Pigment Epitheliopathy

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    PURPOSE: To investigate the natural course of pachychoroid pigment epitheliopathy (PPE). DESIGN: A retrospective cohort study. SUBJECTS: From the Kyoto central serous chorioretinopathy (CSC) cohort consisting of 548 patients with CSC as of September 2020, we included consecutive unilateral patients with acute or chronic CSC between January 2013 and December 2016. METHODS: All patients underwent complete ophthalmic examination, including multimodal imaging such as fundus autofluorescence, spectral-domain optical coherence tomography, and fluorescein angiography/indocyanine green angiography and/or optimal coherence tomography angiography. The fellow eyes of eyes diagnosed with CSC were screened for PPE, and their natural course was evaluated. We also evaluated the association of ARMS2 rs10490924, CFH rs800292, TNFRSF10A rs13278062, and GATA5 rs6061548 genotypes with the natural course. MAIN OUTCOME MEASURES: Incidence of CSC, pachychoroid neovasculopathy, and pachychoroid geographic atrophy (GA). RESULTS: In total, 165 patients with unilateral CSC (mean age, 55.7 ± 12.6 years; female, 22.4%) were included from the Kyoto CSC cohort. Among them, 148 (89.7%) were diagnosed as having PPE in their non-CSC eye. Survival analysis revealed that 16.8% of PPE eyes developed CSC during the 6-year follow up, whereas non-PPE eyes did not. Although genetic factors did not have significant association with CSC development (P > 0.05, log-rank test), choroidal vascular hyperpermeability (CVH) and subfoveal choroidal thickness (SFCT) were significantly associated with CSC incidence (P = 0.001, log-rank test). Survival analysis showed that eyes without CVH and eyes with SFCT < 300 μm did not develop CSC during the 6-year follow-up. Pachychoroid neovasculopathy developed in only 1 eye with PPE during a follow-up of 46.4 months. Pachychoroid GA did not develop in any of the studied eyes. CONCLUSIONS: This study revealed a natural history of PPE in a relatively large Japanese cohort. Choroidal vascular hyperpermeability and SFCT were significant risk factors for the development of CSC in PPE eyes. Although the current results cannot be generalized for all eyes with PPE, these findings present an important clinical implication

    Individual Radiation Exposure Dose Due to Support Activities at Safe Shelters in Fukushima Prefecture

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    Immediately after the accidents in the nuclear power stations in Fukushima on March 11, the Japanese Government ordered the evacuation of the residents within a 20-km radius from the station on March 12, and asked various institutions to monitor the contamination levels of the residents. Hirosaki University, which is located 355 km north of Fukushima City, decided to send support staff to Fukushima. This report summarizes the results of the exposure of 13 individual teams from March 15 to June 20. The support teams surveyed more than 5,000 people during this period. Almost all subjects had external contamination levels of less than 13 kcpm on Geiger-Müller (GM) survey meter, which is categorized as “no contamination level.” The 1st team showed the highest external exposure dose, but the 4th team onward showed no significant change. Subsequently, the internal radiation exposure was measured using a whole body counter that indicated undetectable levels in all staff members. Although the measured external radiation exposure dose cannot have serious biological effects on the health of an individual, a follow-up study of the residents in Fukushima and other regions where the radioactive material has spread will be required for a long time

    Integrating Preprocessing Operations into Deep Learning Model: Case Study of Posttreatment Visual Acuity Prediction

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    Designing a deep neural network model that integrates clinical images with other electronic medical records entails various preprocessing operations. Preprocessing of clinical images often requires trimming of parts of the lesions shown in the images, whereas preprocessing of other electronic medical records requires vectorization of these records; for example, patient age is often converted into a categorical vector of 10-year intervals. Although these preprocessing operations are critical to the performance of the classification model, there is no guarantee that the preprocessing step chosen is appropriate for model training. The ability to integrate these preprocessing operations into a deep neural network model and to train the model, including the preprocessing operations, can help design a multi-modal medical classification model. This study proposes integration layers of preprocessing, both for clinical images and electronic medical records, in deep neural network models. Preprocessing of clinical images is realized by a vision transformer layer that selectively adopts the parts of the images requiring attention. The preprocessing of other medical electrical records is performed by adopting full-connection layers and normalizing these layers. These proposed preprocessing-integrated layers were verified using a posttreatment visual acuity prediction task in ophthalmology as a case study. This prediction task requires clinical images as well as patient profile data corresponding to each patient's posttreatment logMAR visual acuity. The performance of a heuristically designed prediction model was compared with the performance of the prediction model that includes the proposed preprocessing integration layers. The mean square errors between predicted and correct results were 0.051 for the heuristic model and 0.054 for the proposed model. Experimental results showed that the proposed model utilizing preprocessing integration layers achieved nearly the same performance as the heuristically designed model

    Effectiveness of Reduced-fluence Photodynamic Therapy for Chronic Central Serous Chorioretinopathy

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    [Purpose] To investigate the 2-year effectiveness of reduced-fluence photodynamic therapy (rf-PDT) for chronic central serous chorioretinopathy (cCSC). [Design] Retrospective cohort study. [Participants] A total of 223 consecutive patients with newly diagnosed cCSC with active serous retinal detachment (SRD) were included from May 2007 to June 2017 and followed up for at least 2 years. Patients who underwent ocular treatment other than cataract surgery before the beginning of recruitment and those who had macular neovascularization at baseline were excluded. [Methods] All patients underwent a comprehensive ophthalmic evaluation, including measurements of best-corrected visual acuity (BCVA), slit-lamp examination, dilated fundus examination, color fundus photography, fundus autofluorescence, fluorescein angiography, indocyanine green angiography, and spectral-domain OCT. An inverse probability of treatment weighting (IPTW) methodology was applied to balance 18 baseline characteristics between patients who received rf-PDT (rf-PDT group) and those who did not receive treatment (controls). Inverse probability of treatment weighting survival analysis and regression were performed. [Main Outcome Measures] The proportion of patients whose BCVA at 24 months was the same or improved compared with the baseline visual acuity (VA) (VA maintenance rate). [Results] A total of 155 eyes (rf-PDT group: 74; controls: 81) were analyzed. The patients’ backgrounds were well balanced after IPTW with standardized differences of < 0.10. An IPTW regression analysis revealed that the VA maintenance rate was significantly higher in the rf-PDT group than in the controls (93.6% vs. 70.9%, P < 0.001, 12 months; 85.7% vs. 69.8%, P = 0.019, 24 months). The rf-PDT group tended to show better VA improvement, but was not statistically significant (–0.06 vs. –0.008, P = 0.07, 12 months; –0.06 vs. –0.03, P = 0.32, 24 months). An IPTW Cox regression showed a significantly higher rate of complete SRD remission in the rf-PDT group (hazard ratio, 5.05; 95% confidence interval, 3.24–7.89; P < 0.001). [Conclusions] The study suggests the beneficial effect of rf-PDT for cCSC for both VA maintenance and higher proportion of complete SRD remission in the clinical setting

    Monthly Precipitation Collected at Hirosaki, Japan: Its Tritium Concentration and Chemical and Stable Isotope Compositions

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    Monthly precipitation samples were collected at Hirosaki, Aomori Prefecture from January 2018 to December 2020 to measure the ion species and stable hydrogen and oxygen isotope ratios in order to understand the regional properties. The tritium concentration ranged from 0.28 to 1.20 Bq/L, with mean values (±S.D.) of 0.52 ± 0.18, 0.67 ± 0.25 and 0.63 ± 0.21 Bq/L in 2018, 2019 and 2020, respectively. This concentration level was almost the same as for Rokkasho, Aomori Prefecture. The tritium concentration had clear seasonal variation: high in the spring and low in the summer. This trend was thought to arise from seasonal fluctuations in the atmospheric circulation. On the other hand, the pH tended to be low, and the electrical conductivity (EC) tended to be high from the winter to the spring. The ion components, which major ion species contained in sea salt, also tended to be high in the winter, and these components had a strong influence on EC. The d-excess values were high in the winter and low in the summer, and when this trend was considered from the viewpoint of the wind direction data in Hirosaki, these dust components were attributed to the northwest monsoon in the winter to the spring coming from the Asian continent

    Distribution of Choroidal Thickness and Choroidal Vessel Dilation in Healthy Japanese Individuals: The Nagahama Study

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    [Purpose] To report fundamental epidemiologic data for choroidal parameters such as choroidal thickness and index of choroidal vascularity in Japanese individuals and to evaluate their correlations with age, sex, systemic parameters, and other ocular parameters. [Design] Population-based cohort study. [Participants] A total of 9850 individuals participated in the first follow-up of the Nagahama Prospective Cohort for Comprehensive Human Bioscience (the Nagahama Study) conducted between 2013 and 2016. [Methods] All participants underwent standardized ophthalmic examinations, including OCT with enhanced depth imaging (EDI; RS-3000 Advance; Nidek). We manually segmented the choroidoscleral interface to measure subfoveal choroidal thickness (SFCT) and calculated the normalized choroidal intensity obtained with EDI (NCIEDI) and choroidal vascularity index (CVI). These are indices of choroidal brightness in OCT and reportedly represent the dilation of choroidal vessels. After summarizing the age-sex stratified distributions of SFCT, NCIEDI, and CVI, their associations with age, sex, axial length (AL), and spherical equivalent (SE) were evaluated using linear regression analysis with adjustments for possible confounders. [Main Outcome Measures] Distribution of SFCT, NCIEDI, and CVI in the healthy Japanese population and their characteristics. [Results] Age-sex standardized SFCT, NCIEDI, and CVI were 291.2 μm, 0.653, and 66.88%, respectively. In both men and women, SFCT was associated negatively with age (P < 0.001) and NCIEDI was associated positively with age (P < 0.001). Although both SFCT and NCIEDI did not differ significantly between men and women overall (P = 0.87 and P = 0.21, respectively), among younger participants (35–50 years of age), men showed significantly greater SFCT than women (P < 0.001). Only in men was CVI associated positively with age (P < 0.001). In the multivariable analysis, SFCT was associated significantly with age, sex, AL, SE, and the interaction term of age and sex (P < 0.001). Independent of SFCT, NCIEDI and CVI were associated significantly with age (P < 0.001). [Conclusions] We report normative Japanese SFCT, NCIEDI, and CVI data using a large general Japanese cohort. The association analysis of SFCT with NCIEDI and CVI suggested that younger individuals have a more lumen-rich choroid for their choroidal thickness than older individuals
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