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KOICHI SHOJI 《Weed Biology and Management》2007,7(1):14-22
Tillage for the "complete inversion" of soil, that is, overturning soil slices 180° was proposed, a "spot plow" was developed and tested to accomplish the task, and a simulation model was evaluated to demonstrate the efficacy of the plow on weed control. A 360 mm wide spot plow was designed to operate at a speed of 1.9 m s−1 for the spot plowing with the least possible lateral displacement of the soil slice by utilizing the inertia of the soil slice and securely rotating it. In field experiments, complete spot inversion required an operating speed of at least 1.6 m s−1 ; at lower speeds, a portion of the soil block was left half-inverted and further lowering led to considerable lateral displacement. The displacement in the forward and lateral directions was minimal, implying that spot plowing is suitable for potential application to and verification of the weed population dynamics model in the field. A simple linear matrix model of the population dynamics of annual weeds was proposed, whereby four layers of soil were set to describe tillage and other ecological events. The effect of tillage on weed control was evaluated by the equilibrium reproduction rate allowed to sustain a stable population of weeds. The simulation model showed that alternately changing the depth of spot plowing had a significant effect on controlling weeds of low-survival-rate seeds, even when some incomplete inversion of the soil slice was taken into account. 相似文献
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HIDEYUKI KANEMOTO KOICHI OHNO KO NAKASHIMA MASASHI TAKAHASHI YASUHITO FUJINO RYOHEI NISHIMURA HAJIME TSUJIMOTO 《Veterinary radiology & ultrasound》2009,50(2):188-194
Contrast-enhanced ultrasound using Sonazoid, a novel contrast medium with a liver-specific Kupffer phase, was evaluated in canine focal liver lesions Twenty-five dogs with a liver mass were given intravenous Sonazoid, and the enhancement pattern in the arterial, portal, and parenchymal phase was characterized. An enhancement defect in the lesion in the parenchymal phase was observed in all malignant lesions, whereas only one of nine benign lesions had a filling defect. The diagnostic value of the presence of a filling defect for malignancy was statistically significant (100% sensitivity, 88.9% specificity, 94.1% positive predictive value, 100% negative predictive value), and was equal to that of hypoenhancement in the portal or delayed phase. The defect pattern (clear or irregular defect) was dependent ( P <0.05) on the types of malignancy (i.e., hepatocellular carcinoma and other types of malignancies). In the arterial phase, five of the six hepatocellular carcinomas had hypervascularity, whereas no other lesion was characterized by hypervascularity. In some dogs, additional lesions that could not be observed with conventional B-mode ultrasonography were detected in the parenchymal phase. The enhancement pattern of Sonazoid, especially in the parenchymal phase, has potential as a diagnostic tool for canine focal liver lesions. 相似文献
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KOICHI NAGATA KIMBERLY A. SELTING CRISTI R. COOK METTA RENSCHLER JIMMY C. LATTIMER 《Veterinary radiology & ultrasound》2011,52(1):114-117
Two cats with a superficial oral squamous cell carcinoma responded favorably to treatment using a 90Sr probe. From one to six fields were applied per tumor, depending on tumor size. The surface dose per treatment ranged from 75 to 150 Gy and the total surface dose ranged from 200 to 500 Gy. Adverse effects were minimal. The cats survived 7 months and 5 years 9 months from the time of diagnosis. These data indicate that with careful patient selection 90Sr may be useful for the treatment of feline oral squamous cell carcinoma in some patients. 相似文献
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HIROHIKO KAGAWA HIDEKI TANAKA TATSUYA UNUMA HIROMI OHTA KOICHIRO GEN KOICHI OKUZAWA 《Fisheries Science》2003,69(2):234-241
ABSTRACT: The in vitro effects of 17,20β-dihydroxy-4-pregnen-3-one(DHP) and prostaglandins (PGE1 , PGE2 , PGF1α ,PGF2α ) on ovulation in the Japanese eel Anguillajaponica were examined. Oocytes with follicle layers at themigratory nucleus stage (approximately 850–900 µmdiameter) were removed using a polyethylene cannula from artificiallymatured fish. At concentrations of 10 and 100 ng/mL,DHP was found to induce both germinal vesicle breakdown and ovulation.The prostaglandins, except for PGE1 , effectively inducedovulation of previously matured oocytes by DHP treatment in vitro .Prostaglandin F2α was the most effective. Asignificant increase in ovulation rate was observed even at a concentrationof 0.01 µg/mL PGF2α .Indomethacin blocked the in vitro ovulation induced by DHPand addition of PGF2α reversed indomethacin-blockedovulation. Actinomycin D and cycloheximide blocked DHP-induced ovulationand PGF2α reversed the effects of both inhibitors. Theseresults indicate that DHP induces ovulation through endogenous prostaglandinsynthesis in the follicle layers of the Japanese eel. 相似文献
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新城疫病毒某水禽分离株经鸡体传代后由非致病型转变为速发型的研究 总被引:8,自引:0,他引:8
于圣青 丁铲 NORIKO KISHIDA HIROSHI ITO HIROSHI KIDA KOICHI OTSUKI TOSHIHIRO ITO 《中国预防兽医学报》2003,25(1):59-64
最近,一株无毒力的新城疫病毒(NDV)在鸡体内繁殖时,变成了强毒株,但致今尚未能证实,经鸡体传代的野生水禽新城疫病毒是否也具有变成速发型毒株的能力,为了通过实验证明从水禽中分离的非致病型NDV可以转变为速发型病毒,我们通过在鸡体内传播鹅源性无毒力株,经气囊接种连续传代9次,随后再在鸡脑内传代5次,结果显示,该病毒的毒力变得很强,致死率可达100%,通过致病性试验证实,其具有典型的速发型病毒特征;融合蛋白裂解位点的序列分析表明,原始的分离株含有无毒力型毒株共有的裂解序列;E-R-Q-E-R/L,而通过鸡体反复传代后,该序列变为致癞 性毒株共有的序列:K-R-Q-K-R/F,这些结果表明,野生水禽中自然存在的无毒力毒株,具有无毒力株相应的序列,但当其在鸡群中传播时,则具有变成高致病性病毒的能力,同时研究表明,鸡体提供了该病毒从非致病型向致病型转变的选择机制。 相似文献
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PARK NAM‐IL MASARU OGASAWARA KOICHI YONEYAMA YASUTOMO TAKEUCHI 《Weed Biology and Management》2001,1(4):222-225
The growth response to fertilizer under different soil texture (light clayey soil and composite soil consisting of the light clayey soil and sand), and the timing of N fertilization (early summer and fall fertilization) were determined for annual bluegrass (Poa annua L.) and creeping bentgrass (Agrostis palustris Huds., var. Penncross) in glasshouse experiments. At the three‐leaf stage, both plant species were treated with 30, 100, 300, 1,000, 3000 or 10 000 p.p.m. (w/v) of N, P2O5 and K2O equivalent to ammonium sulfate (N), calcium superphosphate (P) and potassium chloride (K). Three weeks after fertilization, the dry weight of shoots or roots was measured. Both plant species were more sensitive to N than to P or K; however, creeping bentgrass required a higher rate of N (1000 p.p.m.) for maximum shoot and root growth than did the weed (300 p.p.m., N). Shoot growth of both plant species was strongly affected by the timing of N fertilization and soil texture; their shoot responses to N increased in the order: composite soil > light clayey soil, and early summer N fertilization > fall N fertilization, and this tendency was especially marked for creeping bentgrass. These results suggest that the response of annual bluegrass to fertilizer is similar to that of creeping bentgrass; however, the two plants are different in regard to the N requirement or their relationship between response to N and application timing and/or soil texture. 相似文献
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