• Title/Summary/Keyword: selectivity

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The Link Between Stereoselectivity and Spin Selectivity in Intermolecular and Intramolecular Photochemical Reactions

  • Griesbeck, Axel G.
    • Journal of Photoscience
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    • v.10 no.1
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    • pp.49-60
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    • 2003
  • How stereo selectivity in singlet and triplet photocycloaddition and photocyclization reactions, respectively, is linked to spin selectivity and how this link affects our understanding of photochemical reaction mechanisms, is described in this review. As illustrative examples, the Paterno-Buchi reaction and the Norrish-Yang cyclization are described with emphasis on triplet biradical structure and dynamics.

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An experimental study on the mesh size selectivity for whelk (Buccinum opisthoplectum) (세고리물레고둥(Buccinum opisthoplectum)의 망목 크기 선택성에 대한 실험적 고찰)

  • KIM, Seonghun;JUNG, Jung-Mo;BAEK, Sena
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.58 no.1
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    • pp.1-9
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    • 2022
  • In this study, the selection action on the mesh in the net pot for whelk (Buccinum opisthoplectum) is experimentally considered, and the selectivity was compared by the SELECT model and the Nashimoto's method with the probability model according to the contact shape of the mesh and the whelk. The experiments of the mesh size selectivity was conducted for two mesh sizes: 70 mm (inner stretched size 65.4 mm) and 44 mm (inner stretched size 39.5 mm). Selectivity experiments were conducted three times in total for each mesh size used 264 whelks. In addition, Nashimoto's method analyzed the retention probability using probability model for whether the mesh passed or not based on the carapace width of the whelk. As a result of the selectivity analysis, the 50% selection carapace width for the mesh size of 70 mm was similar to 43.62 mm in the SELECT model and 42.64 mm in the Nashimoto's method. However, the 44 mm mesh with relatively small mesh size showed differences of 40.01 mm and 26.80 mm, respectively. As for the mesh size selectivity of whelk, it was found that the smaller the mesh size, the lower the selectivity. In addition, in the selectivity study on the mesh size of whelk, an evaluation method that closely considers the contact shape between the mesh and the target species is required.

The estimation of the optimum mesh size selectivity of a drift net for yellow croaker (Larimichthys polyactis) using by the SELECT model (참조기 (Larimichthys polyactis) 유자망에 있어서 SELECT모델에 의한 적정 망목선택성 곡선 추정)

  • Kim, Seong-Hun;Park, Seong-Wook;Lee, Kyoung-Hoon;Yang, Yong-Su
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.48 no.1
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    • pp.10-19
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    • 2012
  • The mesh selectivity of a drift net for yellow croaker (Larimichthys polyactis) was examined in field experiments with six different net mesh size (40, 45, 50, 55, 60 and 65mm) from April to December, 2008 in the coastal areas of Jeollanam-do in Korea. The total catch of 6,748 consisted of yellow croaker (n=6,310; 89.1% of total catch), common mackerel (n=158; 5.6%) and other species (n=280; 9.6%). The selectivity curve for yellow croaker was fit by the models of selectivity curve in SELECT method. The optimal mesh size for 50% retention for minimum landing size (191mm) of yellow croaker was estimated as 49.6mm-51mm by selectivity curves. And the bi-normal model for the selectivity curve was found to fit the data best.

Study on the mesh selectivity of a drum shaped pot for finely-striate buccinum (Buccinum striatissimum) in the eastern coastal waters of Korea (우리나라 동해안 북형 통발에 대한 물레고둥(Buccinum striatissimum)의 망목 선택성에 관한 연구)

  • KIM, Seonghun;JEONG, Seong-Jae;PARK, Chang-Doo;KIM, Pyungkwan
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.56 no.3
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    • pp.193-201
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    • 2020
  • The mesh selectivity of a drum shaped pot for finely-striate buccinum (Buccinum striatissimum) was conducted a total of eight times with four different mesh sizes (22, 35, 50 and 60 mm) from May to September, 2019 in the eastern coastal waters of Korea. The size selectivity analysis was estimated by the SELECT method to express logistic selectivity curves. In the results, the catch of finely-striate buccinum was occupied about 90% in the total catch weight. The equation of the master curve of selectivity was estimated to s(R) = exp(-7.778R+9.983)/[1+exp(-7.778R+9.983)]. The relative shell height of 50% selection was 1.284 and the selection range (SR) was 0.282. The optimal mesh size for 50% selection on the minimum maturation size (75 mm, Shell height) was estimated more than 60 mm by the master selectivity curve.

Analysis of body size selectivity of by-catch using the cover net method for a shrimp beam trawl

  • Kim, Yonghae
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.51 no.2
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    • pp.171-178
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    • 2015
  • Selectivity and by-catch are the main features used to define fish catch for fisheries management or to determine fishing gear efficiency. A fish girth distribution analysis was carried out to determine the retention rate of juveniles discarded and to establish common selectivity for a multispecies catch. Total body length, body weight, and girth of juvenile fish retained in the cod-end and cover net separately were collected using an 18-mm mesh cover net during 12 fishing trials with a 41-mm cod-end beam trawl. The by-catch weight ratio in the cod-end was twice that of the by-catch ratio in number. The 50% selectivity of body length and 50% girth of redfin velvet fish were not significantly different between the cod-end and cover net, whereas those of other fish species were significantly different between the cod-end and cover net. The difference in 50% selectivity girth of other fish between the cod-end and cover net was similar between cod-end mesh size and cover net mesh size. Furthermore, the difference in 50% body length selectivity of other fish between the cod-end and cover net was almost double the difference in girth. Girth selectivity in a multispecies catch using towed fishing gear was effectively used to determine fish and net mesh size.

A study on the mesh selectivity of hairtail (Trichiurus lepturus) caught by coastal drift gill net (연안 유자망에 의한 갈치(Trichiurus lepturus)의 망목 선택성에 관한 연구)

  • KIM, Seonghun;KIM, Pyungkwan;JEONG, Seong-Jae;LEE, Kyounghoon;OH, Wooseok
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.55 no.4
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    • pp.285-293
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    • 2019
  • The mesh selectivity of hairtail (Trichiurus lepturus) caught by coastal drift gill net was examined in field experiments with three different mesh sizes (45, 50 and 55 mm) from October to November, 2013 in the coastal areas of south-west of Jeju province. The mesh selectivity tests were conducted with the experimental net to be set middle part of conventional driftnets. The mesh selectivity tests were carried out the total of four times. The selectivity curve was estimated by the Kitahara's and Fujimori's method. In the results, the catch number of hairtail was 653 (125.8 kg) and occupied 34.8% in total catches weight. The optimal mesh size for 50% selection on the minimum landing size (180 mm, AL) and the first maturity size (260 mm, AL) of hairtail were estimated as 47.2 mm and 64.5 mm by master selectivity curves, respectively.

Involvement of Amino Acids Flanking Glu7.32 of the Gonadotropin-releasing Hormone Receptor in the Selectivity of Antagonists

  • Wang, Chengbing;Oh, Da Young;Maiti, Kaushik;Kwon, Hyuk Bang;Cheon, Jun;Hwang, Jong-Ik;Seong, Jae Young
    • Molecules and Cells
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    • v.25 no.1
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    • pp.91-98
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    • 2008
  • The Glu/$Asp^{7.32}$ residue in extracellular loop 3 of the mammalian type-I gonadotropin-releasing hormone receptor (GnRHR) interacts with $Arg^8$ of GnRH-I, conferring preferential ligand selectivity for GnRH-I over GnRH-II. Previously, we demonstrated that the residues (Ser and Pro) flanking Glu/$Asp^{7.32}$ also play a role in the differential agonist selectivity of mammalian and non-mammalian GnRHRs. In this study, we examined the differential antagonist selectivity of wild type and mutant GnRHRs in which the Ser and Pro residues were changed. Cetrorelix, a GnRH-I antagonist, and Trptorelix-2, a GnRH-II antagonist, exhibited high selectivity for mammalian type-I and non-mammalian GnRHRs, respectively. The inhibitory activities of the antagonists were dependent on agonist concentration and subtype. Rat GnRHR in which the Ser-Glu-Pro (SEP) motif was changed to Pro-Glu-Val (PEV) or Pro-Glu-Ser (PES) had increased sensitivity to Trptorelix-2 but decreased sensitivity to Cetrorelix. Mutant bullfrog GnRHR-1 with the SEP motif had the reverse antagonist selectivity, with reduced sensitivity to Trptorelix-2 but increased sensitivity to Cetrorelix. These findings indicate that the residues flanking $Glu^{7.32}$ are important for antagonist as well as agonist selectivity.

Selectivity Estimation for Multidimensional Sequence Data in Spatio-Temporal Databases (시공간 데이타베이스에서 다차원 시퀀스 데이타의 선택도추정)

  • Shin, Byoung-Cheol;Lee, Jong-Yun
    • Journal of KIISE:Databases
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    • v.34 no.1
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    • pp.84-97
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    • 2007
  • Selectivity estimation techniques in query optimization have been used in commercial databases and histograms are popularly used for the selectivity estimation. Recently, the techniques for spatio-temporal databases have been restricted to existing temporal and spatial databases. In addition, the selectivity estimation techniques focused on time-series data such as moving objects. It is also impossible to estimate selectivity for range queries with a time interval. Therefore, we construct two histograms, CMH (current multidimensional histogram) and PMH (past multidimensional histogram), to estimate the selectivity of multidimensional sequence data in spatio-temporal databases and propose effective selectivity estimation methods using the histograms. Furthermore, we solve a problem about the range query using our proposed histograms. We evaluated the effectiveness of histograms for range queries with a time interval through various experimental results.

Effects of Reaction Conditions on Cobalt-Catalyzed Fischer-Tropsch Synthesis: Interactions between Operating Factors

  • Ajamein, Hossein;Sarkari, Majid;Fazlollahi, Farhad;Atashi, Hossein
    • Journal of the Korean Chemical Society
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    • v.55 no.5
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    • pp.824-829
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    • 2011
  • In Fischer-Tropsch Synthesis, because of few reactants ($H_2$, CO), scarce operating parameters affected on efficiency especially the selectivity of products. In this research, effect of operating parameters on the selectivity of Co-Mn-$TiO_2$ Fischer-Tropsch synthesis catalyst were studied by design of experimental procedure and Taguchi method. According to this research, interactions between operating factors have a crucial effect on light products selectivity. Among these interactions, (temperature${\times}$feed ratio) has the main influence on light hydrocarbons selectivity. It was concluded that temperature and feed ratio ($H_2$/CO) were the most integral operating parameters for much greater selectivity of light hydrocarbons.

A Compressed Histogram Technique for Spatial Selectivity Estimation (공간 선택률 추정을 위한 압축 히스토그램 기법)

  • Chung, Jae-Du;Chi, Jeong-Hee;Ryu, Keun-Ho
    • 한국공간정보시스템학회:학술대회논문집
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    • 2004.12a
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    • pp.69-74
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    • 2004
  • Selectivity estimation for spatial query is very important process in finding the most efficient execution plan. Many works have been performed to estimate accurately selectivity. Although they deal with some problems such as false-count, multi-count, they require a large amount of memory to retain accurate selectivity, so they can not get good results in little memory environments such as mobile-based small database. In order to solve this problem, we propose a new technique called MW histogram which is able to compress summary data and get reasonable results. It also has a flexible structure to react dynamic update. The experimental results showed that the MW histogram has lower relative error than MinSkew histogram and gets a good selectivity in little memory.

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