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Ermson Z. Nyakatawa David A. Mays Kozma Naka James O. Bukenya 《Agroforestry Systems》2012,86(2):129-140
Agroforestry presents an opportunity to increase land productivity and improve cash flow by combining income from crop or animal production and forestry on the same land. In addition, agroforestry offers numerous environmental benefits such as increased diversity of plants and animals, nutrient recycling, erosion control, and carbon (C) sequestration. We investigated the effect of grazing and forage enhancement on total soil C (TSC), soil nitrogen (N), and phosphorus (P) dynamics in a goat (Capra aegagrus hircus)??loblolly pine (Pinus taeda L.) silvopasture system on a Kipling silt loam soil (fine, smectitic, thermic, Typic Paleudalfs) at Epes, Alabama from 2006 to 2010. In 2007, the soil in the silvopasture plots was characterized by low pH, low TSC, and was deficient in N and P. Four years after tree thinning and after 3?years of grazing in June 2010, the silvopasture plots still depicted low soil pH (<6) and TSC levels less than 20?g?kg?1. TSC content in all the silvopasture plots in June 2010 were generally similar to levels obtained after thinning and prior to grazing in May 2007. However, soil disturbance for liming, fertilizer incorporation, and forage planting increased soil N and P levels, but resulted in lower TSC in the enhanced forage plots compared to the other treatments. Grazing increased N and P levels during the study period. Our study suggests that in the long-term, grazing without additional soil management practices can improve soil fertility through nutrient recycling and C sequestration and thereby making the goat-loblolly silvopasture system both environmentally and economically sustainable. 相似文献
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Matazaemon Uchida Hiroshi Naka Yasuo Irie Toshio Fujita Minoru Nakajima 《Pesticide biochemistry and physiology》1974,4(4):451-455
The neuroexciting activity of DDT and its analogs to produce repetitive responses on the nerve cord of Periplaneta americana was determined using the extracellular electrode method. The convulsive activity on P. americana and the insecticidal effect on Callosobruchus chinensis were also examined. It was found that the convulsive and insecticidal activities increase almost proportionally with increase in the neuroexciting activity within a set of p,p′-substituted DDT analogs. The intimate connections among these biological effects suggest that symptoms such as convulsion and death caused by DDT analogs are closely related with their neuroexcitory effect and there is a common mode of action in spite of differences in insect species. 相似文献
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K Iizasa RS Fiske O Ishizuka M Yuasa J Hashimoto J Ishibashi J Naka Y Horii Y Fujiwara A Imai S Koyama 《Science (New York, N.Y.)》1999,283(5404):975-977
Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine caldera. The sulfide body is located on the caldera floor at a depth of 1210 to 1360 meters, has an area of 400 by 400 by 30 meters, and is notably rich in gold and silver. The discovery of a large Kuroko-type polymetallic sulfide deposit in this arc-front caldera raises the possibility that the numerous unexplored submarine silicic calderas elsewhere might have similar deposits. 相似文献
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Hypothalamic mTOR signaling regulates food intake 总被引:1,自引:0,他引:1
Cota D Proulx K Smith KA Kozma SC Thomas G Woods SC Seeley RJ 《Science (New York, N.Y.)》2006,312(5775):927-930
The mammalian Target of Rapamycin (mTOR) protein is a serine-threonine kinase that regulates cell-cycle progression and growth by sensing changes in energy status. We demonstrated that mTOR signaling plays a role in the brain mechanisms that respond to nutrient availability, regulating energy balance. In the rat, mTOR signaling is controlled by energy status in specific regions of the hypothalamus and colocalizes with neuropeptide Y and proopiomelanocortin neurons in the arcuate nucleus. Central administration of leucine increases hypothalamic mTOR signaling and decreases food intake and body weight. The hormone leptin increases hypothalamic mTOR activity, and the inhibition of mTOR signaling blunts leptin's anorectic effect. Thus, mTOR is a cellular fuel sensor whose hypothalamic activity is directly tied to the regulation of energy intake. 相似文献
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The Wiener theory of nonlinear system identification was applied to a three-stage neuron chain in the catfish retina in order to determine the functional relationship between the artificial polarization of the horizontal cell membrane potential and the resulting discharge of the ganglion cell. A mathematical model was obtained that can predict quantitatively, with reasonable accuracy, the nonlinear, dynamic behavior of the neuron chain. The applicability of the method is discussed. We conclude that this is a very powerful method in the analysis of information transfer in the central nervous system. 相似文献