• Title/Summary/Keyword: Knot

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Effects of Soil Addition and Subsoil Plowing on the Change of Soil Chemical Properties and the Reduction of Root-Knot Nematode in Continuous Cropping Field of Oriental Melon (Cucumis melo L.) (시설참외 연작재배지 토양의 객토 및 심토반전이 토양 화학성 변화와 토양선층 억제효과에 미치는 영향)

  • Jun, Han-Sik;Park, Woo-Chul;Jung, Jae-Sik
    • Korean Journal of Environmental Agriculture
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    • v.21 no.1
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    • pp.1-6
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    • 2002
  • To elucidate the effect of soil addition and subsoil plowing on the change of sell chemical properties and the reduction of root-knot nematode, this experiment carried out in continuous cropping field of protected oriental melon (Cucumis melo L.). Soil addition reduced electric conductivity (E. C.) from 4.3 to 1.8 dS/m (58%), available $P_2O_5$ from 406 to 182 mg/kg (55%) and organic matter content from 16 to 11 g/kg (31%). Population densities of root-knot nematode in soil reduced as much as 89%, 84%, and 69% at first year, third years, and of five years later, respectively The effects of subsoil plowing were similar to that of soil addition. E. C. and phosphate were reduced from 4.30 to 1.98 dS/m (54%) and phosphate from 406 to 329 mg/kg (19%), respectively. Population densities of root-knot nematode reduced as much as 71%, 67%, and 42% after 1, 3, and 5 years, respectively Subsoil plowing reduced nematode densities only for three years.

Biological Control of Root-knot Nematode by Lysobacter capsici YS1215 (Lysobacter capsici YS1215를 이용한 뿌리혹선충(Root-knot nematode)의 생물학적 방제)

  • Lee, Yong-Sung;Park, Yun-Suk;Kim, Sun-Bae;Kim, Kil-Yong
    • Korean Journal of Soil Science and Fertilizer
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    • v.46 no.2
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    • pp.105-111
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    • 2013
  • The experiments were carried out to investigate the biocontrol potential of Lysobacter capsici YS1215 on root-knot nematode and to characterize its lytic enzyme activities. L. capsici YS1215 showed chitinase and gelatinase activities on the medium containing 0.5% chitin or 0.5% gelatin as substrates. Cell growth of L. capsici YS1215 was highest at 6 days, and the highest activities of chitinase (4.0 unit $ml^{-1}$) and gelatinase (7.43 unit $ml^{-1}$) were observed on 3 and 5 days after incubation, respectively. To investigate the effect of L. capsici YS1215 on tomato growth and nematode infection, the plants in pot trial were treated with bacterial culture (BC), half of bacterial culture (HBC), only bacterial medium (BM), tap water (TW) and commercial nematicide (CN). HBC treatd plants showed the higher shoot fresh weight and dry weight on $5^{th}$week after incubation while BM, HBC and BC had consistently higher values than TW at $9^{th}$ week. HBC appeared to be the highest shoot fresh length at $9^{th}$ week. Both CN and BC showed lower number of egg mass, root gall, and population of juveniles in soil compared to BC, HBC, BM and TW. These results suggest that L. capsici YS1215 with its strong ability of lytic enzyme production can be one of the most significant candidates for biocontrol agents against root-knot nematodes.

Investigation on the Description Method of Extrusion Die Surface using B-Spline Surface Scheme (B-스플라인 곡면기법을 이용한 압출금형 곡면의 표현방법에 관한 연구)

  • 유동진;임종훈
    • Transactions of Materials Processing
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    • v.12 no.2
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    • pp.142-150
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    • 2003
  • To construct the extrusion die surface, a B-Spline surface scheme based on the cubic B-Spline curve interpolation method is proposed in the present work. The inlet and outlet profiles are described with B-Spline curves by using the centripetal method for uniform parameterization. The interior control points of surface are generated using the derivative characteristics of B-Spline curve. A complete B-Spline surface is constructed by using appropriate coordinate transformation and knot deletion. In the present study, a quantitative measure for the control of surface is suggested by introducing the tangential vector and inclination angles at the inlet and outlet sections. To verify the validity of the proposed method, automatic surface generation is carried out for the various types of extrusion die surface.

Finite Type Invariants and Virtual Twist Moves of Virtual Knots

  • Jeong, Myeong-Ju
    • Kyungpook Mathematical Journal
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    • v.46 no.3
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    • pp.449-461
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    • 2006
  • Generalizing twist moves of classical knots, we introduce $t(a_1,{\cdots},a_m)$-moves of virtual knots for an $m$-tuple ($a_1,{\cdots},a_m$) of nonzero integers. In [4], M. Goussarov, M. Polyak and O. Viro introduced finite type invariants of virtual knots and Gauss diagram formulae giving combinatorial presentations of finite type invariants. By using the Gauss diagram formulae for the finite type invariants of degree 2, we give a necessary condition for a virtual long knot K to be transformed to a virtual long knot K' by a finite sequence of $t(a_1,{\cdots},a_m)$-moves for an $m$-tuple ($a_1,{\cdots},a_m$) of nonzero integers with the same sign.

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AN INJECTIVITY THEOREM FOR CASSON-GORDON TYPE REPRESENTATIONS RELATING TO THE CONCORDANCE OF KNOTS AND LINKS

  • Friedl, Stefan;Powell, Mark
    • Bulletin of the Korean Mathematical Society
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    • v.49 no.2
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    • pp.395-409
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    • 2012
  • In the study of homology cobordisms, knot concordance and link concordance, the following technical problem arises frequently: let ${\pi}$ be a group and let M ${\rightarrow}$ N be a homomorphism between projective $\mathbb{Z}[{\pi}]$-modules such that $\mathbb{Z}_p\;{\otimes}_{\mathbb{Z}[{\pi}]}M{\rightarrow}\mathbb{Z}_p{\otimes}_{\mathbb{Z}[{\pi}]}\;N$ is injective; for which other right $\mathbb{Z}[{\pi}]$-modules V is the induced map $V{\otimes}_{\mathbb{Z}[{\pi}]}\;M{\rightarrow}\;V{\otimes}_{\mathbb{Z}[{\pi}]}\;N$ also injective? Our main theorem gives a new criterion which combines and generalizes many previous results.