The natural abundance of 15N (expressed as δ15N per mil relative to air N2) in the tissues and the change of 15N abundance during the digestion processess in cattle, pig, and goat were investigated. ...The 15N abundances of cattle tissues differed by about 3.5‰ with high values in heart, urinary bladder and diaphragm. The ages of cattle did not affect on the 15N abundances of liver and kidney in cattle. The 15N abundances of urine were lower, and those of feces were a little higher than the values of diets in cattle and pigs. The δ15N values of milk and blood were higher than the value of diets. Two peaks of 15N abundances at forestomach and caecum were observed during the digestion processes of diet in goats. The mechanisms of the variation of 15N abundances in animal bodies were briefly discussed.
Vacancy concentration distribution is estimated by measuring deep levels induced by N2-vacancy complexes in the wafers which are prepared from Si crystals grown by different pulling rate. It is found ...that the vacancy concentration is very low inside the OSF-ring and a little low in the ring region. Two kinds of the vacancy density profiles are observed in the specimens without the OSF-ring which are prepared from Si crystals grown by fast (1.4 mm/mm) and slow (0.4 mm/mm) pulling rate: one is a gradual and the other is a abrupt zigzag profile. We interpret the gradual profile is caused by macroscopic density change of the octahedral void defects and the abrupt variation is accompanied with the growth striation.
Rovers that are used to explore craters on the Moon or Mars require the mobility to negotiate sandy slopes, on which slippage can easily occur. Such slippage can be reduced by actively readjusting ...the attitude of the rovers. By changing attitude, rovers can modify the position of their center of gravity and the wheel-soil contact angle. In this study, we discuss the effects of attitude changes on downhill sideslip based on the slope failure mechanism and experiments on reconfiguring the rover attitude and wheel angles. We conducted slope-traversing experiments using a wheeled rover under various roll angles and wheel angles. The experimental results show that the contact angle between wheels and slopes has a dominant influence on sideslip when compared with that of readjusting the rover's center of gravity.
The surfaces of both the Moon and Mars are covered with loose soil, with numerous steep slopes along their crater rims. Therefore, one of the most important requirements imposed on planetary rovers ...is their ability to minimize slippage while climbing steep slopes, i.e., the ability to generate a drawbar pull with only a small amount of slippage. To this end, the wheels/tracks of planetary rovers typically have parallel fins called lugs (i.e., grousers) on their surface. Recent studies have reported that these lugs can substantially improve the traveling performances of planetary rovers. Therefore, in this study, we conducted experiments using lightweight two-wheeled and mono-tracked rovers to provide a quantitative confirmation regarding the influence of lugs on the traveling performances of planetary rovers. Based on our experimental results, we confirmed that, although an increase in the number of lugs contributes to the high traveling performance of wheeled rovers, it does not contribute much to that of tracked rovers. Furthermore, an increase in lug height improves the traveling performances of both types of rovers.
In experimental studies, deterioration of the transmural myocardial contractility occurs heterogeneously in coronary hypoperfusion. That is, the subendocardium is the first layer to become vulnerable ...to the ischemia in the acute reduction of the coronary flow according to J. I. Hoffman (1987), K. A. Reimer and R. B. Jennings (1979) and P. Colonna et al. (1999). With a longer period of ischemia, necrosis progresses heterogeneously from the endocardium to the epicardium (the wavefront phenomenon) by K. A. Reimer and R. B. Jennings (1979). After the release of 15 min coronary occlusion, the ischemic myocardium progressively recovers its contractility. This post-ischemic recovery in contractility has also been demonstrated to be heterogeneous along the myocardial wall, but is much quicker at the subepicardial side than at the subendocardium, with a "subendocardial post ischemic stunning" according to R. Boli et al. (1989). However, at present, there is still a serious deficiency in the clinical information concerning the transmyocardial functional heterogeneity across the human ventricular wall. The "phased tracking method", adopted in this study, has advantages over the conventional clinical diagnostic methods because of its higher spatial and temporal resolution together with its ease of handling for repetitive use according to H. Kanai et al. (1997) and H. Kanai and Y. Koiwa (2001). In this preliminary clinical study, we examined whether the transmural systolic function obtained by the phased tracking method is capable of supplying new information about the ischemic myocardium under ischemia and after coronary reperfusion.
One of the most important requirements imposed on planetary rovers is the ability to minimize slippage while climbing slopes covered with loose soil. Therefore, at the design stage of the rovers, it ...is necessary to evaluate the traveling performance of their locomotion mechanisms over a slope. However, to conduct traveling tests over slopes, the sandbox in which the tests are conducted must be tilted; it is difficult and even dangerous to make a steep slope because of the heavy weight of the sandbox. Therefore, in this paper, we propose a new method for estimating the traveling performance of a wheeled rover over a slope. In this method, we estimate the slip ratio for different slope angles on the basis of traction tests over a flat terrain. To verify the proposed method, we conducted slope-climbing tests and traction tests in a sandbox using a two-wheeled rover with various types of wheels. Furthermore, we compared the slip ratios estimated from the slope-climbing tests with those estimated from the traction tests. From these comparisons, we concluded that the proposed method can accurately estimate the traveling performance of a planetary rover over a slope.
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