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51.
Shigeya Maeda Toshihiko Kawachi Koichi Unami Junichiro Takeuchi Tomoki Izumi Syunsuke Chono 《Paddy and Water Environment》2009,7(3):163-175
A fuzzy optimization model is developed to allocate allowable total nitrogen (T-N) loads to distributed nonpoint sources (NPSs)
and point sources (PSs) in a watershed for river water quality management using the linear programing technique. The watershed
is divided into uniform grid cells on which T-N loads issuing from NPSs such as paddy fields, upland crop fields and cities
are controlled. A geographic information system integrated with the digital elevation model facilitates computation of route
lengths of surface and subsurface flows from cells to a river running through the watershed. The T-N loads discharged from
their sources are assumed to decay, subject to distance-related first-order kinetics. As management goals, maximizations of
total allowable NPS loads, total allowable PS loads and total yield of rice are considered from environmental and economic
viewpoints. A prime constraint is an effluent limitation standard for the aggregate amount of loads that arrive at the downstream
end of the river. The fuzzy sets theory helps appropriately describe vague attitudes of decision-makers (i.e., stakeholders
and management authorities) in terms of constraints and conflicting goals. An application of the fuzzy optimization model,
developed as an improvement over our last nonfuzzy model, to a real watershed in Shiga prefecture, Japan, demonstrates that
the fuzzy model embodies our last model, and is capable of creating management alternatives for T-N load allocation in a more
practical and flexible manner. 相似文献
52.
Junichiro Takeuchi Toshihiko Kawachi Koichi Unami Shigeya Maeda Tomoki Izumi 《Paddy and Water Environment》2009,7(1):33-43
A cell-based distributed watershed model is developed which enables us to simulate the hydrological and hydraulic aspects
of the watershed in a refined fashion. With three-zoned cell profiling, the model is composed of three sub-models; tank model
for a surface water zone, soil moisture model for a surface soil zone, and unconfined shallow groundwater flow model for a
subsurface zone. Inclusion of the soil moisture sub-model modified to reroute the infiltration, routed from the tank sub-model,
into the return flow and the groundwater recharge features the model. The groundwater flow sub-model, numerically approximated
by use of the finite volume method and the implicit time-marching scheme, considers a network of on-farm drainage canals as
internal boundaries, which is an essential need for modeling the watershed including farmlands. Cascade-linking of the three
sub-models in a cell and assembling of all the cells over the entire watershed domain provides the global equations system
to be solved. Applicability of the model is demonstrated with its practical application to a real watershed in that paddy
and upland crop fields take great part of the land-use practice. It is then indicated in a quantified manner that rice farming
significantly contribute as a major groundwater recharger in an irrigation period to fostering and conservation of regional
water resources. Along with appropriately profiling a cell, the model is so versatile and tough that it can be applied without
difficulty to a watershed of diverse terrains and land-uses and the computations can stably be carried out. It is thus concluded
that the model presently developed could be a powerful “watershed simulator” to investigate and assess the time-varying hydro-environmental
properties of a watershed while separating and integrating the hydrological and hydraulic components of particular importance. 相似文献
53.
Chung Sarit Takeuchi Junichiro Fujihara Masayuki Oeurng Chantha 《Paddy and Water Environment》2019,17(2):255-263
Paddy and Water Environment - In Cambodia, rice production is important for the majority of rural populations as the main source of income. However, historical extreme flood events, especially the... 相似文献
54.
Summary Because of the strategic and industrial importance of natural rubber, there has been renewed interest in cultivating guayule (Parthenium argentatum). This study was performed for assessing feasibility of guayule cultivation with waters high in dissolved salts. The test materials included six USDA selections (11591, 11605, 11619, 11646, 12229 and N576), one cultivar (593) and one hybrid (4265XF). Seedlings were grown for l0 weeks in a greenhouse and transplanted in the spring and in the summer into lysimeters (unit surface dimension of 6 x 7 m) containing loamy sand or silt loam. They were grown with simulated irrigation waters having four levels of salinity (0.8, 2.4, 4.6 and 7.2 dSm–1 with SAR < 13) and an additional water containing 5 mmol L–1 of Mg at 2.4 dSm–1. In the spring planting, over 90% of the transplants survived when furrow irrigated weekly with waters of 4.6 dSm–1 or less. However, transplant growth for the first several months was reduced by half at irrigation water salinity of 4.6 dSm–1. In the summer planting, several fold increases in mortality and growth reduction occurred. Dry top Shrub yields after the two growing seasons following the spring planting averaged 10 Mg ha–1 at 0.8 dSm–1 and declined on the average 15 and 51 % when irrigated with waters of 4.6 and 7.2 dSm–1 respectively. The amount of water used to produce one ton of dry shrub was 1,600 m3 with waters of 0.8 and 4.6 dSm–1, and 1,900 m3 with water of 7.2 dSm–1. The contents of rubber in the shrubs averaged 61 g kg–1 at 0.8 dSm–1 and increased to 70 g kg–1 at 7.2 dSm–1. whereas resin contents were not affected by the salt treatments. Resulting rubber yields were reduced on the average by 8.5 and 44% at 4.6 and 7.2 dSm–1. respectively, because of the reduction in shrub yields. Selection N576 produced the largest rubber yields with the highest rubber content at all levels of salinity. Increasing Mg concentrations from 0.5 to 5 mmol L–1 in the irrigation waters reduced neither yields nor transplant survival. Yield reductions observed here appeared to be related to Na, but not Mg.Contribution from Texas Agricultural Experiment Station. Supported in part by a grant from the Latex Commission, USDA and by the US-Israel Binational Agricultural Research and Development (BARD) fund 相似文献
55.
Traver D Akashi K Manz M Merad M Miyamoto T Engleman EG Weissman IL 《Science (New York, N.Y.)》2000,290(5499):2152-2154
Dendritic cells (DCs) are critical in both initiating adaptive immune responses and maintaining tolerance to self antigens. These apparently contradictory roles have been suggested to depend on different subsets of DCs that arise from either myeloid or lymphoid hematopoietic origins, respectively. Although DC expression of CD8alpha is attributed to a lymphoid origin, here we show that both CD8alpha+ and CD8alpha- DCs can arise from clonogenic common myeloid progenitors in both thymus and spleen. Thus, expression of CD8alpha is not indicative of a lymphoid origin, and phenotypic and functional differences among DC subsets are likely to reflect maturation status rather than ontogeny. 相似文献
56.
57.
Morioka Shinsuke Vongvichith Bounsong Marui Junichiro Okutsu Tomoyuki Phomikong Pisit Avakul Piyathap Jutagate Tuantong 《Fisheries Science》2019,85(4):667-675
Fisheries Science - Growth and reproduction of the Thai river sprat Clupeichthys aesarnensis (Teleostei: Clupeidae) in Sirindhorn Reservoir, Thailand, and Nam Ngum Reservoir, Laos, were... 相似文献
58.
59.
Liu FG Miyamoto MM Freire NP Ong PQ Tennant MR Young TS Gugel KF 《Science (New York, N.Y.)》2001,291(5509):1786-1789
A large body of diverse comparative data now exists for a major phylogenetic synthesis of the higher-level relationships among eutherian (placental) mammals. We present such a phylogenetic synthesis using the composite trees or supertrees from the combined and separate analyses of their published molecular and morphological source phylogenies. Our combined and separate supertrees largely support the same suprafamilial taxa and orders, but different interordinal clades. These similarities and differences reinforce the continuing contributions of morphological studies, while highlighting the growing influence of molecular information on the field. As current summaries of past research, our supertrees emphasize opportunities for future work, while providing a step toward the eventual integration of the data and characters themselves. 相似文献
60.
Yurimoto H Abe K Abe M Ebihara M Fujimura A Hashiguchi M Hashizume K Ireland TR Itoh S Katayama J Kato C Kawaguchi J Kawasaki N Kitajima F Kobayashi S Meike T Mukai T Nagao K Nakamura T Naraoka H Noguchi T Okazaki R Park C Sakamoto N Seto Y Takei M Tsuchiyama A Uesugi M Wakaki S Yada T Yamamoto K Yoshikawa M Zolensky ME 《Science (New York, N.Y.)》2011,333(6046):1116-1119
Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in (16)O relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid. 相似文献