Analysis of return flows in a tank cascade system in Sri Lanka

In Sri Lanka, irrigation reservoirs (tanks) are usually connected sequentially and form cascades along the landscape. A study was carried out in the Anuradhapura District in the dry zone of Sri Lanka to understand the role of return flows in such tank cascade systems. The water balance of a tank cascade system was estimated using hydrological data collected over a one-year period. The system was extended about 25 km along a river composed of three small reservoirs having the command area of 31, 55, and 55 ha, respectively. In this system, about 46% of seepage water from tanks entered the paddy fields of the command area. The crop consumed part of the water and the rest returned to the downstream tank through the drainage canals. Percolation loss in the command areas was low (3.6 mm/day) since a considerable portion of the percolation returned to the downstream tank. These results showed that return flows, which are generally disregarded in the water budget, contributed considerably to the water supply of the tank cascade system.     

Several properties of humic acids

In the preceding paper¹), it was shown that the elementary composition of soil humic acid changed regularly with the progress of humification. Afterwards, the author conducted several experiments on the base exchange capacity, the content of hydrolysable nitrogen, the resistance to oxidizing reagent, the electrolyte coagulation and X-ray analysis of various humic acids. These experimental resu1ts will be given in this report.     

Scaling-up from tree to stand transpiration for a warm-temperate multi-specific broadleaved forest with a wide variation in stem diameter

Previous studies have demonstrated a clear relationship between diameter at breast height (DBH) and tree transpiration (Q _T) in multi-specific broadleaved forests. However, these studies were conducted with a limited range of tree sizes and species, and thus many multi-specific broadleaved forests fall outside these conditions. Therefore, this study examined the relationship between DBH and Q _T in a warm-temperate multi-specific broadleaved forest (n = 12 species) with a wide range of tree sizes (5.0–70.0 cm DBH) using the Granier-type heat dissipation method. The results showed that, although sap flow density varied between individual trees and species, there was a significant relationship between log Q _T and log DBH (r ² = 0.66, P < 0.001) because of the strong dependence of sapwood area on DBH. This study confirmed the applicability of the relationship for the stand transpiration (E _C) estimates even in a multi-specific broadleaved forest with a wide variation in DBH. Our results also revealed that selecting the sample trees in descending order of DBH effectively reduced potential errors in E _C estimates for a specific sample size, as larger trees contribute more to E _C. This information should be useful for future studies investigating the transpiration of multi-specific broadleaved forests, reducing errors during the scaling-up procedure.     

Low-frequency spin dynamics in a canted antiferromagnet

Resistively detected nuclear spin relaxation measurements in closely separated two-dimensional electron systems reveal strong low-frequency electron-spin fluctuations in the quantum Hall regime. As the temperature is decreased, the spin fluctuations, manifested by a sharp enhancement of the nuclear spin-lattice relaxation rate 1/T1, continue to grow down to the lowest temperature of 66 millikelvin. The observed divergent behavior of 1/T1 signals a gapless spin excitation mode and is a hallmark of canted antiferromagnetic order. Our data demonstrate the realization of a two-dimensional system with planar broken symmetry, in which fluctuations do not freeze out when approaching the zero temperature limit.     

Unraveling the spin polarization of the ν = 5/2 fractional quantum Hall state

The fractional quantum Hall (FQH) effect at filling factor ν = 5/2 has recently come under close scrutiny, as its ground state may possess quasi-particle excitations obeying nonabelian statistics, a property sought for topologically protected quantum operations. However, its microscopic origin remains unknown, and candidate model wave functions include those with undesirable abelian statistics. We report direct measurements of the electron spin polarization of the ν = 5/2 FQH state using resistively detected nuclear magnetic resonance. We find the system to be fully polarized, which unambiguously rules out the most likely abelian contender and lends strong support for the ν = 5/2 state being nonabelian. Our measurements reveal an intrinsically different nature of interaction in the first excited Landau level underlying the physics at ν = 5/2.     

Evaluation of QT interval prolongation in dogs with heart failure

Comparison of the QT interval and corrected QT interval values that were calculated by the methods of Bazett (QTc1) and Fridericia (QTc2) were made between dogs with or without cardiac diseases to determine the influence of the QT interval on canine heart failure. Upon comparison of the measured values on ECG between the cardiac disease and non-cardiac disease groups, it was observed that the heart rate(HR) was significantly higher in the cardiac disease group than in the non-cardiac disease group, although the QT interval was similar in the two groups. The QTc1 and QTc2 were significantly longer in the cardiac disease group than in the non-cardiac disease group. With the progression of the New York Heart Association Class, the HR tended to increase. The QTc1 and QTc2 became significantly prolonged with the progression of heart failure. Nevertheless, because Bazett's correction formula is known to overcorrect when the HR is high, it was considered that the QTc1 was actually overcorrected by high HR with the progression of heart failure. The QTc2, on the other hand, was only slightly influenced by HR, suggesting that the prolongation was due to the progression of heart failure. These results suggest that the prolongation of QTc2 in cardiac disease reflects the substantial prolongation of the QT interval without the influence of HR. It is suggested that the QTc2 could be a useful parameter for assessing the degree of heart failure in dogs with cardiac disease.     

黄土高原半干旱区辽东栎的树干液流动态

利用Granier树干液流测定系统,长期监测黄土高原半干旱区延安市南郊天然辽东栎林优势木的树干液流,并同步监测环境因子(空气温度、湿度、太阳辐射、土壤含水量)。分析3株优势木边材液流在生长季内各月份的日变化特征以及液流通量密度与环境因子的关系。结果显示:辽东栎液流日变化总体上与太阳辐射和空气水气压亏缺呈相同趋势,但液流峰值出现时间较早,通常为10:00左右。随着生长季内物候变化,液流通量密度总体表现为前期(4—6月)较低、中后期(7—9月)较高、末期(10月)迅速下降的变化趋势。采用指数饱和曲线函数对液流通量密度和空气水气压亏缺进行拟合,有效地反映了各月份液流通量密度对空气水气压亏缺的响应特征。各月份的曲线特征和拟合参数的差异表明,蒸腾耗水过程也受到土壤水分状况等其他因素的影响。