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131.
Sirirat Kiatpathomchai P. Michael Schmitz T. S. Amjath Babu Sutonya Thongrak 《Paddy and Water Environment》2008,6(3):319-326
Rice and shrimp farming are two important economic activities in rural southern Thailand that compete each other in land allocation
leading to land use conflicts. Moreover, it can be observed that the conversion of rice fields to shrimp farms is already
extended from coastal areas to the inlands. These conversions are making more area be saline which is essential condition
for shrimp cultivation but deleterious for rice farming. We are looking at the unidirectional externalities originating from
the conversion which brings the productivity of adjacent rice fields further down. This study attempts to quantify the external
effects on rice yield and efficiency of rice farming by constructing three models. Model I, we assess the rice yield function
by using the multiple linear regression while in Model II, we attempt to delineate the technical efficient frontier of rice
farms by using an input oriented non-parametric approach, so called data envelopment analysis. Model III, we probe into the
factors influencing technical efficiency scores using the Tobit regression. Database of the study is constituted by primary
survey data from 120 rice farms in Songkhla province for the crop year 2004/2005. The 30 out of 120 sample farms have been
affected by externality of shrimp farming. The empirical results of all three models show that shrimp farming externalities
caused a production drop of 467–515 kg paddy rice per ha and significantly affect the technical efficiency of rice farms.
The measures of internalizing this externality are discussed. 相似文献
132.
Off-axis crustal thickness across and along the east pacific rise within the MELT area 总被引:1,自引:0,他引:1
JP Canales RS Detrick S Bazin AJ Harding JA Orcutt 《Science (New York, N.Y.)》1998,280(5367):1218-1221
Wide-angle seismic data along the Mantle Electromagnetic and Tomography (MELT) arrays show that the thickness of 0.5- to 1. 5-million-year-old crust of the Nazca Plate is not resolvably different from that of the Pacific Plate, despite an asymmetry in depth and gravity across this portion of the East Pacific Rise. Crustal thickness on similarly aged crust on the Nazca plate near a magmatically robust part of the East Pacific Rise at 17 degrees15'S is slightly thinner (5.1 to 5.7 kilometers) than at the 15 degrees55'S overlapping spreading center (5.8 to 6.3 kilometers). This small north-south off-axis crustal thickness difference may reflect along-axis temporal variations in magma supply, whereas the across-axis asymmetry in depth and gravity must be caused by density variations in the underlying mantle. 相似文献
133.
JR Delaney DS Kelley MD Lilley DA Butterfield JA Baross WSD Wilcock RW Embley M Summit 《Science (New York, N.Y.)》1998,281(5374):222-230
Seafloor diking-eruptive events represent the irreducible, quantum events of upper oceanic crustal accretion. They record events by which a large portion of the oceanic crust has formed through geological history. Since 1993, the U.S. Navy's real-time Sound Surveillance System has allowed location of ongoing acoustic signatures of dike emplacement and basalt eruptions at ridge crests in the northeast Pacific. These diking-eruptive events trigger a sequence of related, rapidly evolving physical, chemical, and biological processes. Magmatic volatiles released during these events may provide nutrients for communities of subseafloor microorganisms, some of which thrive in high-temperature anaerobic environments. Many of the organisms identified from these systems are Archaea. If microorganisms can thrive in the water-saturated pores and cracks within deep, volcanically active portions of our planet, other hydrothermally active planets may harbor similar life forms. 相似文献
134.
Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission 总被引:2,自引:0,他引:2
MH Acu?a JEP Connerney P Wasilewski RP Lin KA Anderson CW Carlson J McFadden DW Curtis D Mitchell H Reme C Mazelle JA Sauvaud C d'Uston A Cros JL Medale SJ Bauer P Cloutier M Mayhew D Winterhalter NF Ness 《Science (New York, N.Y.)》1998,279(5357):1676-1680
The magnetometer and electron reflectometer investigation (MAG/ER) on the Mars Global Surveyor spacecraft has obtained magnetic field and plasma observations throughout the near-Mars environment, from beyond the influence of Mars to just above the surface (at an altitude of approximately 100 kilometers). The solar wind interaction with Mars is in many ways similar to that at Venus and at an active comet, that is, primarily an ionospheric-atmospheric interaction. No significant planetary magnetic field of global scale has been detected to date (<2 x 10(21) Gauss-cubic centimeter), but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of Mars is reported. 相似文献
135.
Benign masses in the pericardium of two dogs 总被引:1,自引:0,他引:1
Two miniature Schnauzer dogs were treated for pericardial masses. In one dog the mass consisted of necrotic fat that was attached to the apex of the pericardium by a pedicle. No obvious communication with the abdomen was present. The second dog had a peritoneopericardial hernia associated with a chronic cystic haematoma. In each case the mass was presumed to have arisen following congenital displacement of the omentum into the pericardium. The pericardial mass was removed and subtotal pericardectomy performed in both dogs. Recovery was complete in each case. 相似文献
136.
不同利用方式下草地土壤微生物及土壤呼吸特性 总被引:7,自引:0,他引:7
通过对呼伦贝尔羊草(Leymus chinensis)草甸草原土壤呼吸特性及土壤微生物的测定,研究了3种不同利用方式(围封、放牧和刈割)对天然草地土壤呼吸特性及土壤微生物的影响,为草甸草原土壤呼吸研究提供基础理论依据。结果表明:不同利用方式下土壤呼吸速率、土壤微生物量碳含量与土壤酶活性(除脲酶)均表现为草地围封比放牧和刈割呼吸速率高(含量高、活性强);土壤微生物量氮含量、脲酶活性和微生物数量表现为草地放牧和刈割比围封的含量高(活性强、数量多);土壤微生物量碳、氮含量、土壤酶活性(除脲酶)和土壤微生物数量均以表层(0~10cm)最高(活性最强、数量最多),随着土层深度增加而降低(活性下降、数量减少)。土壤呼吸速率与微生物量碳、土壤酶活性(除过氧化氢酶)成正相关,与微生物量氮、过氧化氢酶和微生物数量成负相关,其中只与微生物量氮相关性显著,而其余之间均不显著。 相似文献
137.
138.
Identification of procyanidins in cocoa (Theobroma cacao) and chocolate using high-performance liquid chromatography/mass spectrometry 总被引:1,自引:0,他引:1
Hammerstone JF Lazarus SA Mitchell AE Rucker R Schmitz HH 《Journal of agricultural and food chemistry》1999,47(2):490-496
Monomeric and oligomeric procyanidins present in cocoa and chocolate were separated and identified using a modified normal-phase high-performance liquid chromatography (HPLC) method coupled with on-line mass spectrometry (MS) analysis using an atmospheric pressure ionization electrospray chamber. The chromatographic separation was achieved using a silica stationary phase in combination with a gradient ascending in polarity. This qualitative report confirms the presence of a complex series of procyanidins in raw cocoa and certain chocolates using HPLC/MS techniques. Although both cocoa and chocolate contained monomeric and oligomeric procyanidin units 2-10, only use of negative mode provided MS data for the higher oligomers (i.e., >pentamer). Application of this method for qualitative analysis of proanthocyanidins in other food products and confirmation of this method as a reliable quantitative tool for determining levels of procyanidins in cocoa, chocolate, and other food products are currently being investigated. 相似文献
139.
Cleber dos Santos Simio Grecica Mariana Colombo Marcos Josu Schmitz Patrícia Baptista Ramos Marcelo Borges Tesser Wilson Wasielesky Jos María Monserrat 《Aquaculture Research》2020,51(4):1731-1742
This study investigated the effects of the inclusion of Mauritia flexuosa fruit pulp in the diet on the growth performance, economic benefit, muscle composition, total contents of carotenoids and flavonoids, chromaticity parameters, total antioxidant capacity, and lipid peroxidation in the hepatopancreas and muscle of the juvenile shrimp Litopenaeus vannamei (weighing 1.26 ± 0.023 g). Five diets (37% protein, 10% lipid) consisting of 0 (control), 1.25%, 2.50%, 5.00% and 10.00% (w/w) M. flexuosa fruit pulp were formulated and provided to the shrimps (n = 50 per tank, treatments in triplicate) for 31 days. Results showed that there were no significant differences between the treatments in terms of the growth capacity, chromaticity parameters, muscle composition and total flavonoid content of shrimps (p > .05). However, the carotenoid content in the muscle and hepatopancreas of the shrimps was significantly increased due to the dietary carotenoids present in M. flexuosa fruit pulp (p < .05). This increase in the carotenoid content directly favoured the increase in the antioxidant capacity in the hepatopancreas and muscle of the shrimps (R2 = 0.99 and R2 = 0.97 respectively; p < .05). There was also a direct relationship between the carotenoid content and the decrease in lipid peroxidation in the hepatopancreas (R2 = 0.90; p < .05). The feed cost kg?1 in terms of weight gain and protein production decreased with the inclusion of high levels of M. flexuosa fruit pulp, reaching 8.11% and 18.76% of cost reduction, respectively, with the addition of 5.00% of M. flexuosa fruit pulp. Therefore, the inclusion of M. flexuosa fruit pulp in the diets of shrimp can increase the carotenoid content and the antioxidant capacity in the hepatopancreas and muscle, reduce lipid peroxidation in the hepatopancreas, and probably provide economic benefits for the rearing of juvenile shrimps. 相似文献
140.