Search

In recent years, while the number of elderly lower limb amputees has been increasing, the use rate of lower limb prosthesis among the elderly has been low due to the risk of falling. Knee joints in the transfemoral prosthesis play an important role in regaining the gait ability of amputees. Particularly, the electronically controlled knee joint enables full prevention, by a system that automatically adjusts the optimal knee flexion resistance force based on the estimation of the gait state. However, it is difficult for the user to predict how much load is applied to the knee joint, which is one of the references for adjusting the bending resistance. This reduces the intuitiveness of the control system given to the user. In this study, we developed a robotic knee prosthesis that prevents falling with a proposed gait model to control the locking mechanism of knee flexion. Finally, we conducted experiments with the developed knee joint comparing the passive-type knee joint. From these experiments, we confirmed that our robotic knee prosthesis prevented falling certainly. The effectiveness of fall prevention is shown after the experiment.

Individuals with cerebral palsy use electric wheelchairs due to their abnormal gait caused by paralysis and other symptoms. However, it is difficult for them to operate the wheelchair joystick because of their suddenly occurring uncontrollable, involuntary movements and the difficulty they have maintaining their posture. In this study, we developed a control system, which suppresses the effects of involuntary movement. This system is capable of controlling electric wheelchairs as intended by individuals with tension-athetosis-type cerebral palsy. We demonstrated the experiments to compare the stability of operation by normal system and the proposed system. Finally, we showed the effectiveness of the proposed system in the straight running experiment.

This study describes a calculation of the brightness temperature obtained from the spaceborne precipitation radar to utilize possible uses of precipitation estimates. Since the radar viewed from space measures emission and scattering signals from the earth, the brightness temperature at the radar's frequency is obtained from the noise power measured by the radar. The measurement accuracy of the radar's brightness temperature is also computed from the signal characteristics of the noise power. This study analyzes the noise power data of the Dual-frequency precipitation radar (DPR), whose frequency is at 13.6 and 35.5 GHz, onboard the Global Precipitation Measurement mission's (GPM's) core satellite. The calibrated brightness temperature data obtained from the DPR show the regional gradient between ocean and land surfaces and the emission signal from precipitation even if the measurement accuracy of the radar's brightness temperature is about 30 (50) K for the Ku-band (Ka-band) channel.

Algorithms to determine the thermodynamic phase state of precipitation observed from spaceborne radar are provided in this section. After briefly describing the classical methods to determine the thermodynamic phase of precipitation at the surface, some advanced methods to separate solid precipitation regions from liquid precipitation regions in the vertical profiles of radar measurements are described.

As the Japanese Global Precipitation Measurement (GPM) product, the Global Satellite Mapping of Precipitation (GSMaP) has been provided by the Japan Aerospace Exploration Agency (JAXA) to distribute hourly global precipitation map with 0.1° × 0.1° lat/lon grid. Since JAXA started near-real-time processing of the GSMaP on November 2007, there have been various significant improvements to the GSMaP. This paper summarizes GSMaP products and related algorithms in the GPM era and shows validation results in Japan and the United States.

The circular polarization of light scattered by biological tissues provides valuable information and has been considered as a powerful tool for the diagnosis of tumor tissue. We propose a non-staining, non-invasive and in-vivo cancer diagnosis technique using an endoscope equipped with circularly polarized light-emitting diodes (spin-LEDs). We studied the scattering process of the circularly polarized light against cell nuclei in pseudo-healthy and cancerous tissues using the existing Monte Carlo method. The calculation results indicate that the resultant circular polarizations of light scattered in pseudo tissues shows clear difference in a wide range of detection angle, and the sampling depth depends on those detection angles. The structure of the endoscope probe comprising spin-LEDs is designed based on the calculation results, providing structural and depth information regarding biological tissues simultaneously., 17pages, 3 figures

In this study, the spatial variability in precipitation at a 0.1° scale is investigated using long-term data from the Tropical Rainfall Measuring Mission Precipitation Radar. Marked regional heterogeneities emerged for orographic rainfall on characteristic scales of tens of kilometers, high concentrations of small-scale systems (100 km) result in more rainfall over the adjacent ocean. Finescale hourly data represented the abrupt asymmetric fluctuation in rainfall across the coastline in the tropics and subtropics (30°S–30°N). Significant diurnal modulations in the rainfall due to large-scale systems are found over tropical offshore regions of vast landmasses but not over small islands or in the midlatitudes between 30° and 36°. Rainfall enhancement over small tropical islands is generated by abundant afternoon rainfall, which results from medium-scale storms that are regulated by the island size and inactivity of rainfall over coastal waters.

Observations of the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) over 16 yr yielded hundreds of large precipitation systems (≥100 km) for each 0.1° grid over major rainy regions. More than 90% of the rainfall was attributed to large systems over certain midlatitude regions such as La Plata basin and the East China Sea. The accumulation of high-impact snapshots reduced the significant spatial fluctuation of the rain fraction arising from large systems and allowed the obtaining of sharp images of the geographic rainfall pattern. Widespread systems were undetected over low-rainfall areas such as regions off Peru. Conversely, infrequent large systems brought a significant percentage of rainfall over semiarid tropics such as the Sahel. This demonstrated an increased need for regional sampling of extreme phenomena. Differences in data collected over a period of 16 yr were used to examine sampling adequacy. The results indicated that more than 10% of the 0.1°-scale sampling error accounted for half of the TRMM domain even for a 10-yr data accumulation period. Rainfall at the 0.1° scale was negatively biased in the first few years for over more than half of the areas because of a lack of high-impact samples. The areal fraction of the 0.1°-scale climatology with a 50% accuracy exceeded 95% in the ninth year and in the fifth year for those areas with rainfall >2 mm day−1. A monotonic increase in the degree of similarity of finescale rainfall to the best estimate with an accuracy of 10% illustrated the need for further sampling.

In Japan, the number of people who have difficulty walking has been increasing with the rise in the aging population and that of people with physical disabilities. Individuals with athetosis-type cerebral palsy may use electric wheelchairs due to abnormal walking. However, since they have problems with fine motor control, including the occurrence of involuntary movements and difficulty maintaining posture, they have difficulty intentionally controlling their hand movements. Therefore, they cannot operate a joystick, even if they desire to use electric wheelchairs, and there are risks of accidents. In this study, by considering the arch structure of hand, we developed a new joystick grip that enables the suppression of involuntary movement. We evaluated our proposed grip by comparing running stability with a conventional grip, and demonstrated the effectiveness of proposed method.

The number of lower limb amputations in Japan has recently been increasing. Lower limb amputation is classified based on the amputated part,and its two main types are below-knee (28.4%) and above-knee (58.8%). Especially for patients with above-knee amputation, an above-knee prosthesis with artificial knee and ankle joints is commonly applied. This prostheses also vary according to an individual's activity level. Thus there are varieties of uses of above-knee prostheses. Therefore, various knee joints are being developed corresponding to various activity levels. Passive multi linkage-type knee joints aim to guarantee the stability of the stance phase during walking, and electronically controlled knee joints use a hydraulic cylinder to provide stability in both the swing and stance phases as well as during slope walking and so on. As described above, many knee joints focused on walking are commercially available. But in recent years knee joints focusing on other everyday activities, such as sitting or rising, are being developed. However, there has been no assistive prosthesis designed to enable the standing action involved in stopping in a state where the knee remains slightly flexed. In this study, we developed a robotic prosthesis to provide stability during standing as well as during normal walking. A ratchet mechanism was used for the knee joint, and it reproduced the flexion extension motion of the knee. We also tried to electronically control the movement of the claw of the ratchet mechanism based on the state transition model by finite state machine. Furthermore, the effectiveness of the developed robot prosthesis was shown in a walking experiment by a healthy person.

We demonstrate that the rate of development of cumulus clouds, as inferred from the so-called geostationary satellite “rapid-scan” measurements, is a good proxy for convective cloud top vertical velocity related to deep convective clouds. Convective cloud top vertical velocity is estimated from the decreasing rate of infrared brightness temperature observed by the Multi-functional Transport SATellite-1R (MTSAT-1R) over the ocean south of Japan during boreal summer. The frequency distribution of the estimated convective cloud top vertical velocity at each height is shown to distribute lognormally, and it is consistent with the statistical characteristics of direct measurements acquired in previous studies.

Reproducibility of summer precipitation over northern Eurasia in climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) is evaluated in comparison with several observational and reanalysis datasets. All CMIP5 models under- and overestimate precipitation over western and eastern Eurasia, respectively, and the reproducibility measured using the Taylor skill score is largely determined by the severity of these west–east precipitation biases. The following are the two possible causes for the precipitation biases: very little cloud cover and very strong local evaporation–precipitation coupling. The models underestimate cloud cover over Eurasia, allowing too much sunshine and leading to a warm bias at the surface. The associated cyclonic circulation biases in the lower troposphere weaken the modeled moisture transport from the Atlantic to western Eurasia and enhance the northward moisture flux along the eastern coast. Once the dry west and wet east biases appear in the models, they become amplified because of stronger evaporation–precipitation coupling. The CMIP5 models reproduce precipitation events well over a time scale of several days, including the associated low pressure systems and local convection. However, the modeled precipitation events are relatively weaker over western Eurasia and stronger over eastern Eurasia compared to the observations, and these are consistent with the biases found in the seasonal average fields.

This paper demonstrates the impact of the enhancement in detectability by the dual-frequency precipitation radar (DPR) on board the Global Precipitation Measurement (GPM) core observatory. By setting two minimum detectable reflectivities—12 and 18 dBZ—artificially to 6 months of GPM DPR measurements, the precipitation occurrence and volume increase by ~21.1% and ~1.9%, respectively, between 40°S and 40°N.GPM DPR is found to be able to detect light precipitation, which mainly consists of two distinct types. One type is shallow precipitation, which is most significant for convective precipitation over eastern parts of subtropical oceans, where deep convection is typically suppressed. The other type is probably associated with lower parts of anvil clouds associated with organized precipitation systems.While these echoes have lower reflectivities than the official value of the minimum detectable reflectivity, they are found to mostly consist of true precipitation signals, suggesting that the official value may be too conservative for some sort of meteorological analyses. These results are expected to further the understanding of both global energy and water budgets and the diabatic heating distribution.

This study investigated the drop size distribution (DSD) observed by the Dual-frequency Precipitation Radar (DPR) onboard the Global Precipitation Measurement (GPM) core satellite, which makes the world’s first dual-frequency preciptation observations by space-borne radar. Four years have passed since the launch of the GPM core satellite, and data have been accumulated. This study focuses on the characteristics of DSD derived from the GPM/DPR measurements. In this study, DSD parameters (especially for a mass-weighted mean diameter, Dm) which are estimated based on dual-frequency information derived from GPM/DPR are analyzed with seasonal variations and precipitation characteristics. Values of Dm are generally larger over land than over the oceans. DSD shows seasonal variation, especially over the mid-latitude ocean; Dm in the winter season over the mid-latitude ocean is larger than that in the summer season in both the Northern and Southern hemispheres. Focusing on the mid-latitude North Pacific Ocean close to Japan in winter, precipitation top height is lower and stratiform ratio is higher than those in summer. It suggests that differences of Dm are associated with those of precipitation regimes, such as organized precipitation system in summer season and extratropical frontal systems in winter season.

The number of lower limb amputations in Japan has recently been increasing. This is due to rising incidence of arteriosclerosis obliterans and diabetes resulting in amputations for elderly people. There are two main types of lower limb amputations: below knee (50%) and above knee (35%). Especially, for patients with above-knee amputation, above-knee prosthesis is commonly applied. However, this type of prosthesis usually comes with higher risks of tripping compared to below-knee prosthesis. Thus, it is more difficult to guarantee safe walking. The result is a low percentage of elderly lower limb amputees using prosthesis. In order to prevent unexpected knee bending, which is the main cause of tripping in above-knee prosthesis, a multi-axis knee joint was developed. It prevents knee bending by moving the instantaneous center of rotation behind weight-load line, by adjusting the links structure at heel contact. However, while this mechanism is functional for preventing knee bending in the stance phase, prevention in the swing phase was not considered. As knee bending in the swing stance also causes stumbling, the risk of tripping and falling remains hiah. In this study, we developed a robot prosthesis that prevents falling by controlling the links position of the knee joint with an actuator based on the state transition and using a finite state machine that models the walking state. By controlling the linkage mechanism, we achieved correspondence to knee bending at every point of the stance and swing phases. Furthermore, we confirmed fall prevention and normal walking motion in experiment to demonstrate the effectiveness of the proposed method.

Characteristics and global distribution of regional extreme rainfall are presented using 12 yr of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) measurements. By considering each rainfall event as a set of contiguous PR rainy pixels, characteristic values for each event are obtained. Regional extreme rainfall events are defined as those in which maximum near-surface rainfall rates are higher than the corresponding 99.9th percentile on a 2.5° × 2.5° horizontal-resolution grid. The geographical distribution of extreme rainfall rates shows clear regional differences. The size and volumetric rainfall of extreme events also show clear regional differences. Extreme rainfall rates show good correlations with the corresponding rain-top heights and event sizes over oceans but marginal or no correlation over land. The time of maximum occurrence of extreme rainfall events tends to be during 0000–1200 LT over oceans, whereas it has a distinct afternoon peak over land. There are also clear seasonal differences in which the occurrence over land is largely coincident with insolation. Regional extreme rainfall is classified by extreme rainfall rate (intensity) and the corresponding event size (extensity). Regions of “intense and extensive” extreme rainfall are found mainly over oceans near coastal areas and are likely associated with tropical cyclones and convective systems associated with the establishment of monsoons. Regions of “intense but less extensive” extreme rainfall are distributed widely over land and maritime continents, probably related to afternoon showers and mesoscale convective systems. Regions of “extensive but less intense” extreme rainfall are found almost exclusively over oceans, likely associated with well-organized mesoscale convective systems and extratropical cyclones.

This study reports on the presence of suspicious “extreme rainfall” data in the 2A25 version-7 (V7) product of the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) dataset and introduces a simple method for detecting and filtering out the suspicious data. These suspicious data in V7 are found by comparing the extreme rainfall characteristics in the V7 and version-6 products. Most of the suspicious extremes are located over land, especially in mountainous regions. Radar reflectivities in the suspicious extremes show significant monotonic increases toward the echo bottom. These facts indicate that the suspicious extremes are mainly caused by contamination from ground or sea clutter. A simple thresholding filter for eliminating the suspicious extreme data is developed using common characteristics in the horizontal and vertical rainfall structures and reflectivities in the suspicious extremes. The proposed filter mitigates deformations in the frequency distribution of the surface rainfall rate in the 2A25 V7 product.

A daily gridded precipitation dataset covering a period of more than 57 yr was created by collecting and analyzing rain gauge observation data across Asia through the activities of the Asian Precipitation—Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) project. APHRODITE's daily gridded precipitation is presently the only long-term, continental-scale, high-resolution daily product. The product is based on data collected at 5,000–12,000 stations, which represent 2.3–4.5 times the data made available through the Global Telecommunication System network and is used for most daily gridded precipitation products. Hence, the APHRODITE project has substantially improved the depiction of the areal distribution and variability of precipitation around the Himalayas, Southeast Asia, and mountainous regions of the Middle East. The APHRODITE project now contributes to studies such as the determination of Asian monsoon precipitation change, evaluation of water resources, verification of high-resolution model simulations and satellite precipitation estimates, and improvement of precipitation forecasts. The APHRODITE project carries out outreach activities with Asian countries, and communicates with national institutions and world data centers. We have released open-access APHRO_V1101 datasets for monsoon Asia, the Middle East, and northern Eurasia (at 0.5° × 0.5° and 0.25° × 0.25° resolution) and the APHRO_JP_V1005 dataset for Japan (at 0.05° × 0.05° resolution; see www.chikyu.ac.jp/precip/ and http://aphrodite.suiri.tsukuba.ac.jp/). We welcome cooperation and feedback from users.

Lookup tables for estimating the cloud-top height and visible optical thickness of upper-tropospheric clouds by the infrared brightness temperature TB at 10.8 μm (T11) and its difference from TB at 12 μm (ΔT11–12) measured by a geostationary satellite are presented. These lookup tables were constructed by regressing the cloud radar measurements by the CloudSat satellite over the infrared measurements by the Japanese geostationary multifunctional transport satellite MTSAT-1R. Standard deviations of measurements around the estimates were also displayed as an indicator of the ambiguity in the estimates. For the upper-tropospheric clouds with T11 < 240 K, the standard deviations of the height estimations were less than 1 km. The dependences of the estimates of cloud-top height at each point in T11−ΔT11–12 space on latitude, season, satellite zenith angle, day–night, and land–sea differences were examined. It was shown that these dependences were considered uniform in the tropics except for the region with large satellite zenith angle. The presented lookup tables can provide hourly estimates of cloud-top height and optical thickness at a specified location and are fairly useful in comparing them with ground-based observations such as vertical profiles of humidity and/or wind.

Cloud-top height (CTH) variability in the tropical tropopause layer (TTL) in association with equatorial Kelvin waves is investigated using a new CTH dataset based on MTSAT-1R geostationary satellite measurements with a statistical look-up table constructed based on CloudSat measurements. We focus on a case in the tropical Indian Ocean during October-December 2006, when shipboard radiosonde, TTL water vapor, and 95-GHz cloud radar measurements were taken during the Mirai Indian Ocean cruise for the Study of the MJO-convection Onset (MISMO) field campaign. At 10-15 km, the satellite-based CTH data agree well with the radar echo top heights from shipboard radar reflectivity data. During the MISMO campaign, cloud frequency was suppressed in the warm phase of equatorial Kelvin waves propagating in the TTL. The suppressed-cloud region moves eastward to the western Pacific together with Kelvin waves. We found that changes in CTH occurrence frequency over the vessel in association with Kelvin waves are much greater than those associated with the diurnal cycle. It is expected that the phase of equatorial Kelvin waves is important for the intraseasonal variabilities of both the radiative budget of the tropical atmosphere and water vapor transport in the TTL.

Poly(lactic acid) (PLA) was blended with baked shell powder increasing the content up to 10wt%, and the influence of mixing the powder on the physical properties of the obtained PLA compounds were investigated. The measurements for storage modulus E' revealed that the settled powder will promote the crystallization of PLA. Moreover not only the thermal decomposition but also the biodegradation in compost system for PLA were enhanced by the mixing the powder.

We constructed historical (1900–) high-resolution (0.05° × 0.05°) daily precipitation data over the Japanese land area as part of the product of the “Asian Precipitation – Highly-Resolved Observational Data Integration Towards Evaluation of the Water Resources” (APHRODITE) project. This product APHRO_JP is derived from rain gauge observations and is intended to accurately represent both mean and extreme values. Due to new interpolation techniques developed in APHRODITE, estimation accuracy for orographic precipitation is improved, and bias for long-term amount is reduced, even for the early 20th century in which the observation network was sparse in space. Moreover, the product can be used for statistical analysis of heavy precipitation up to about 150 mm/day, over a long term period (≥ 100 years). APHRO_JP enables diverse research, including validation of meso-scale models and analysis of the longterm extreme precipitation trend in Japan.

The life cycle of deep convective systems over the eastern tropical Pacific (30°N to 30°S, 180 to 90°W) was studied in terms of cloud types, as classified by a split window (11 μm and 12 μm). Hourly split window image data of Geostationary Operational Environmental Satellite (GOES-W) from January 2001 to December 2002 was used in this study. Deep convective systems consist mostly of optically thick cumulus type clouds in the earlier stage and a cirrus type cloud area that increases with time in the later stage. During this analysis period and over the analysis area, the life stage of deep convective system, to a large extent, can be identified by computing the percentage of cirrus type clouds within the deep convective system from a single snap shot of the split window image. Coincident Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) observations were used to study the relationship between the percentage of cirrus type clouds within a deep convective system (i.e., its life stage) and the rainfall rate. It was found that the rainfall rate tends to be larger in the earlier stage of the life cycle when a smaller percentage of cirrus type cloud is present within the deep convection.

A daily gridded precipitation dataset for 1961-2004 was created by collecting rain gauge observation data across Asia through the activities of the Asian Precipitation—Highly Resolved Observational Data Integration Towards the Evaluation of Water Resources (APHRODITE) project. Our number of valid stations was between 5000 and 12,000, representing 2.3 to 4.5 times the data available through the Global Telecommunication System network, which were used for most daily grid precipitation products. APHRODITE’s daily gridded precipitation (APHRO_V0902) is the only long-term (1961 onward) continental-scale daily product that contains a dense network of daily rain gauge data for Asia including the Himalayas and mountainous areas in the Middle East. The product contributes to studies such as the evaluation of Asian water resources, diagnosis of climate change, statistical downscaling, and verification of numerical model simulation and high-resolution precipitation estimates using satellites. We released APHRO_V0902 datasets for Monsoon Asia, Russia and the Middle East (on 0.5° × 0.5° and 0.25° × 0.25° grids) at http://www.chikyu.ac.jp/precip/. Herein, we show the algorithm and input data of APHRO_V0902.

Vertical motion W profiles in the stratiform precipitation region of mesoscale cloud clusters were investigated using wind data observed by VHF Doppler radar installed in western Sumatra Island (0.2°S, 100.32°E). A special mode for W observations was introduced in November 2003, and W data with high accuracy were obtained during most of the period, with fine resolutions of 3 min in time and 150 m in vertical direction. The typical fine structure of W within the nimbostratus in the stratiform precipitation region was investigated by the case study of 6, 8, and 20 November 2003. In the later 2 or 3 h of the stratiform precipitation period, gentle upward motions with small time and height fluctuations were observed over a several-kilometer height range from the middle to upper troposphere. Values of W were weakly positive (0–40 cm s−1) continuously, with little strong upward motion greater than 40 cm s−1 and downward motion.

A poly (L-lactic acid) (PLLA) film, which was blended with baked shell powder, was made and the antibacterial ability, biodegradability and physical properties of it were evaluated. The PLLA film blended with the powder had no antibacterial ability although the PLLA itself had strong antibacterial ability. Moreover the biodegradation rate was faster by blending the powder in PLLA film, and in the thermal and mechanical properties, which are obtained by differential scanning calorimeter (DSC) and tensile tests, there was slightly difference between the unblended PLLA film and the blended PLLA film. So, these results suggest that the antibacterial ability of PLLA is caused by lactic acid which is created in hydrolysis and that the powder neutrizes the lactic acid.

Rapid transitions in the zonal wind (U) around the tropical tropopause within several days are investigated by using the global analysis data and their relation to the amplified Kelvin waves are considered. At 100 hPa, cases with a rapid increase in U (TypeU+ events) are concentrated in the eastern hemisphere, where such cases far outnumber cases that show a rapid decrease in U (TypeU- events). The difference in the number of the two types of events is greatest during the period November-March in the region 90°E-180°E. When only considering cases with a large zonal extent and eastward propagation, the dominance of TypeU+ events in the eastern hemisphere is much more distinct. The asymmetry between the two types is only weakly recorded at lower levels. An amplified and nonlinearly distorted Kelvin wave possibly accounts for predominance of these TypeU+ events at 100hPa. The dominance of TypeU+ events is detected in the basic easterly flow within the upper troposphere, which possibly facilitates the distortion by enhancing the upward propagation of energy and enabling the high intrinsic speed of the wave. In the distorted Kelvin wave, the latitudinal extent of the westerly signal is much smaller than that of the easterly signal.