DEVELOPMENT OF A ROBOT FOR THE MEASUREMENT OF RADIOACTIVE CONTAMINATION AND FERTILITY OF THE SOIL IN FARMLAND.

A tractor-based robot with the capability of real-time assessing and visualizing the radioactive material density and fertility distribution of farmlands has been developed to accelerate the recovery process of the farmlands suffered by the accident of the Fukushima Daiichi Nuclear Power Plant (FDNPP). In a field test at a decontaminated farmland near FDNPP, within-field heterogeneities of soil contamination and fertility are clarified almost in real-time. Results obtained by this robot are consistent with the map by the conventional soil sampling or the history of decontamination activities.

Repetitive afterglow in zirconia by pulsed near-infrared irradiation toward biological temperature sensing.

Photoluminescence provides information about the surrounding environment. In this study, aiming to develop a non-invasive deep body-temperature sensing method, we investigated photoluminescence properties of afterglow zirconia (ZrO2) by pulsed near-infrared (NIR) light irradiation based on the biological temperature. Pulsed light irradiation produced optically stimulated luminescence, followed by afterglow, with the property of repeating 100 times or more. Furthermore, the basic principle of temperature measurement was demonstrated through afterglow decay curve measurements. The use of harmless ZrO2 as a sensing probe and NIR light, which is relatively permeable to living tissues, is expected to realize temperature measurements in the brain and may also facilitate optogenetic treatment.

Modal dispersion characteristics of LP0m modes in a step-index multimode fiber.

A modal interferometer method (MIM) is applied to measure the differential mode delay (DMD) between the L P 0m modes traversing a step-index multimode fiber (SI-MMF). Only linearly polarized radial modes, i.e., L P 0m modes, are excited and transmitted in the SI-MMF by using a single-mode-multimode-single-mode (SMS) fiber structure. The measurement principle is based on investigating a transmitted spectrum through temporal decomposition by means of a Fourier transform. The Fourier-transform-based MIM provides simultaneous measurements of the DMD between the L P 0m modes. The wavelength dependence of the DMD is estimated experimentally in both the 1260-1360 nm and 1450-1625 nm telecommunication bands. The normalized frequency dependence of the DMD is also investigated theoretically. The result suggests that the 1260-1360 nm band is preferable to the 1450-1625 nm band for a mode-division multiplexing (MDM) transmission employing an SI-MMF in terms of realizing a smaller DMD.

Measurement of fiber parameters of pure silica core fibers based on the OTDR technique.

We propose a simple technique based on optical time domain reflectometry (OTDR) for measuring the cutoff wavelength and core radius distributions in a pure silica core fiber for the first time. The proposed technique can simultaneously measure several important fiber parameters such as the mode field diameter, relative-index difference, effective area, and chromatic dispersion, including the cutoff wavelength and core radius. We experimentally demonstrate that our proposed technique can successfully evaluate these fiber parameter distributions and can be applied for the measurements of few-mode and multi-core fibers with pure silica cores using multi-channel OTDR and mode couplers.

Differential mode delay diagnostics for LP modes traversing a few-mode fiber.

We provide differential mode delay (DMD) diagnostics for linearly polarized (LP) modes traversing a few-mode fiber (FMF). We employ a modal interferometer method with a butt coupling mechanism to measure the DMD between any two modes guided in FMFs with step-index (SI) and depressed-cladding profiles. The measurement principle is based on investigating a transmitted spectrum through temporal decomposition by means of a Fourier transform. At least four different temporal waveforms are needed for an FMF supporting four LP modes to estimate the DMD between two different LP modes. A butt coupling mechanism with an air gap between an FMF and a dispersion-shifted fiber is employed for simultaneous DMD measurement. The present diagnostics requires some knowledge of the bending loss characteristics of the FMFs and the butt coupling properties of the circular symmetry modes or circular asymmetry modes in their electric fields. The DMD diagnostics are realized taking the bending loss and butt coupling characteristics into consideration. We present experimental results for the DMD and DMD slope as a function of the wavelength in a 1450-1625 nm telecommunication band.

Diagnosis of modal and chromatic dispersions for the LP01 and LP11 modes through temporal decomposition by means of Fourier transform.

We provide a novel approach for estimating the modal and chromatic dispersions of the LP01 and LP11 modes traversing a two-mode fiber (TMF). A modal interferometer is used to measure the differential group delay (DGD) and chromatic dispersion for the two modes in the 1260-1360 nm telecommunication band. The measurement principle is based on an investigation of a transmitted spectrum through temporal decomposition by means of a Fourier transform. The diagnosis of the DGD and chromatic dispersion for the two modes is discussed theoretically and experimentally. The experimental results obtained here exactly match those obtained previously. The salient feature of the present method is that the modal interferometer configuration makes it possible to measure both the DGD and chromatic dispersion and also estimate the shape of optical pulses traversing a TMF.

Temperature dependence of afterglow in zirconia and its optically-stimulated luminescence by bone-through irradiation for biological temperature probe.

Development of minimally invasive and site-selective biological temperature sensing is quite important in medical field. This study presents a novel temperature sensing technique based on afterglow and optically-stimulated luminescence (OSL). The dependence of afterglow photoluminescent intensity on the environmental temperature of zirconia (ZrO2) phosphor is examined to validate its use as a sensing probe. In addition, assuming the measurement in deep-part of human body, we have applied the information gathered from our validation to observe OSL from the ZrO2 by irradiation with near-infrared laser through a bone sample. This study demonstrates an alternative medical application of phosphor, and introduces an elemental-technology for the temperature sensing.

Unique loss characteristics in TE01 modes of conventional photonic bandgap fibers.

We report modeling that demonstrates the reduction of transmission loss and broadening of the bandwidth of a conventional hollow-core photonic bandgap fiber (PBF). Numerical investigation reveals that transmission loss of the high-order TE01 mode is lower than that of the fundamental HE11 mode in fibers with thick cladding walls. By comparing dispersion curves of PBFs with different core-wall thicknesses, we show that the TE01 mode has weaker coupling strength to a surface mode than the HE11 mode. This result opens the way for a wider transmission band and lower transmission loss in PBFs that are subject to the detrimental effects of surface modes.

Study of fabrication reproducibility of two-mode optical fibers for mode division multiplexing with MIMO processing.

We propose a two-mode optical fiber (TMF) with a low sensitivity of differential modal group delay (DMD) to change of the core radius and the refractive index of the core in the index profile which are major factors for DMD deviation. This was done to achieve high reproducibility of fiber fabrication. The proposed TMF has a graded index (GI) core and a depressed inner cladding, and we optimize structural parameters. We fabricated different kinds of TMFs to confirm the low DMD sensitivity of our proposed fiber. The fabricated TMF showed that the DMD sensitivity to changes in core radius of the TMF was approximately 8 ps/km/µm which is 98% smaller than that of a GI-TMF without a depressed inner cladding.

CD56(dim)CD16(high) and CD56(bright)CD16(-) cell percentages associated with maximum knee extensor strength and incidence of death in elderly.

Physical fitness is an indicator of systemic well-being in humans. Little is known about the role of physical fitness for maintaining systemic health in the elderly. Here, we study elderly subjects to determine the relationships between physical fitness and CD56 and CD16 surface NK cell markers on peripheral blood lymphocytes, as well as to analyze the relationship between the surface markers and incidence of death. We selected 253 independent elderly subjects (122 female; 131 male) who were 79-80 years old. Subjects having a higher proportion of CD56(dim)CD16(high) within CD56(+)CD16(+) cells, or ration of CD56(dim)CD16(high) and CD56(dim)CD16(-) cells had a significant positive correlation with maximum bilateral knee extensor strength/weight (kg) (r = 0.425; P < 0.0001 or r = 0.323; P < 0.0001). In contrast, an increased proportion of CD56(bright)CD16(-) cells within lymphocyte significantly negatively correlated with the maximum bilateral knee extensor strength/weight (kg) (r = -0.290; P = 0.0004); and these subjects had a significantly lower mortality during the 5 years following measurement of death. Therefore, we found that a synergistic effect of the right and left leg muscle strength was associated with proportion of matured NK and NKT cells and induced a low proportion of CD56(bright)CD16(-) cells within lymphocyte. Moreover, the low proportion of CD56(bright)CD16(-) cells was associated with incidence of death. In conclusion, measurements of physical fitness, the proportion of CD56(dim)CD16(high) within CD56(+)CD16(+) cells, the ratio of CD56(dim)CD56(high) and CD56(dim)CD16(-) cells, and the proportion of CD56(bright)C16(-) cells in lymphocytes are important indicators to check elderly health.

Tracking of Pedometer-Determined Physical Activity in Healthy Elderly Japanese People.

BACKGROUND: Tracking refers to the tendency for an individual to maintain their rank within a group over time. This study longitudinally investigated the 8-year tracking of pedometer-determined physical activity among physically independent elderly Japanese people aged 72 to 80 years. METHODS: Steps/day were measured when participants were aged 72 and assessed again after 2, 5, and 8 years. The number of participants with a 2-year follow-up (72 to 74 years) was 177 (101 males, 76 females), with a 5-year follow-up (72 to 77 years) was 183 people (110 males, 73 females), and with an 8-year follow-up (72 to 80 years) was 145 people (91 males, 54 females). Step counts were continuously measured for 1 week in January, April, July, and October during each year of assessment. RESULTS: A high rank correlation coefficient for steps/day exceeding 0.60 was obtained at the 2-, 5- and 8-year follow-up examinations for both males and females. CONCLUSION: This study suggests that the rank within a group of pedometer-determined steps/day remains stable over up to 8 years in healthy Japanese people aged between 72 to 80 years old.

Two mode optical fibers with low and flattened differential modal delay suitable for WDM-MIMO combined system.

We propose two mode optical fibers (TMFs) with minimally low differential modal delay (DMD) slope which are suitable for wavelength division multiplexing and multiple input multiple output (MIMO) combined transmission system. We designed and fabricated three different kinds of TMF, nearly zero-DMD (zTMF), positive-DMD (pTMF) and negative-DMD (nTMF) with a graded index core and a depressed inner cladding. We confirmed that the fabricated zTMF has DMD of below 15 ps/km in the C band and the fabricated pTMF and nTMF have the same degree of effective areas. We also confirmed that a DMD compensation line with a length of 100 km composed of pTMF and nTMF can successfully achieve the best properties of low DMD in the C + L band and low mode conversion.

Longitudinal fiber parameter measurements of multi-core fiber using OTDR.

A novel technique is proposed for measuring the longitudinal fiber parameters of multi-core fiber (MCF). The mode field diameter (MFD)of a fiber link composed of MCF is successfully estimated with a modified optical time domain reflectometer (OTDR). The measurement accuracy of the MFD distribution is revealed by simulation as a function of the mode coupling coefficient. It is also shown that the relative-index difference and chromatic dispersion of MCF can be estimated with the present technique.

Optimized graded index two-mode optical fiber with low DMD, large A(eff) and low bending loss.

An optimized two-mode optical fiber (TMF) with the graded index (GI) profile is designed and fabricated. We clarify an appropriate region of GI-TMF satisfying DMD = 0 ps/km, the large effective area A(eff), and the low bending loss for LP(11) at 1550 nm. According to our fiber design, GI-TMF is successfully fabricated to have the large effective area A(eff) of 150 µm(2) for LP(01) mode, and low DMD below 36 ps/km including zero in the C-band. We expect that our design GI-TMF is suitable for MDM and can reduce MIMO-DSP complexity.

Physical performance and 10-year mortality in a 70-year-old community-dwelling population.

BACKGROUND AND AIMS: Poor physical performance is known to be inversely related to mortality. The purpose of the present study was to determine whether an association between physical performance and 10-year mortality could be extended to a Japanese 70-year-old community-dwelling population, and to compare findings with those found in an octogenarian population. METHODS: Seventy-year-old subjects residing in Niigata city, Japan, participated. Baseline examinations, including a physical performance test of four tests of muscle strength, one test of balance, and one test of agility, were carried out in June 1998 for 600 participants, and these individuals were then followed for 10 years. RESULTS: During the 10-year follow up, 80 subjects died. Cox regression analysis with adjustment for confounding factors showed that high scores in muscle strength tests for lower extremities, such as single-leg and double-leg extensor strength and isokinetic leg extensor power, were found to be related to decreases in total cause mortality. CONCLUSIONS: In an elderly 70-year-old Japanese community-dwelling population, poor muscle strength was found to be an independent predictor of total mortality. Together with our previous findings in an 80-year-old population, the association between poor strength and high mortality may have effects at 70 but not 80 years of age.

Influence of dental occlusion on physical fitness decline in a healthy Japanese elderly population.

The aim of this study was to clarify the relationship between dental occlusion and physical fitness by a longitudinal survey. A sample of 348 subjects (171 men and 177 women) aged 71 was investigated by Eichner index (EI) as an occlusal condition (Class A: no loss; Class B: partial loss; Class C: complete loss) and five types of physical fitness tests and were re-examined 8 years later. The upper 50% were sampled to analyze the correlation between each physical fitness decline and the EI at the baseline by logistic regression models. Logistic regression analyses revealed that leg extensor power (Class B vs. Class A; odds ratio=OR=4.61, p=0.010) and one-leg standing time with eyes open (Class C vs. Class A; OR=4.27, p=0.031) showed significant correlations with the EI at the baseline. In this study, partial or complete loss of occlusion was associated with a decline in leg extensor power or a decrease in one-leg standing time with eyes open. These findings suggest that maintenance of dental occlusion may prevent a decrease in activities of daily living in the elderly.