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        검색결과 69

        5.
        2021.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We study galaxies undergoing ram pressure stripping in the Virgo cluster to examine whether we can identify any discernible trend in their star formation activity. We fi rst use 48 galaxies undergoing different stages of stripping based on Hi morphology, Hi de ficiency, and relative extent to the stellar disk, from the VIVA survey. We then employ a new scheme for galaxy classi fication which combines Hi mass fractions and locations in projected phase space, resulting in a new sample of 365 galaxies. We utilize a variety of star formation tracers, which include g - r, WISE [3.4]-[12] colors, and starburstiness that are de fined by stellar mass and star formation rates to compare the star formation activity of galaxies at different stripping stages. We find no clear evidence for enhancement in the integrated star formation activity of galaxies undergoing early to active stripping. We are instead able to capture the overall quenching of star formation activity with increasing degree of ram pressure stripping, in agreement with previous studies. Our results suggest that if there is any ram pressure stripping induced enhancement, it is at best locally modest, and galaxies undergoing enhancement make up a small fraction of the total sample. Our results also indicate that it is possible to trace galaxies at different stages of stripping with the combination of Hi gas content and location in projected phase space, which can be extended to other galaxy clusters that lack high-resolution Hi imaging.
        5,400원
        8.
        2018.10 구독 인증기관·개인회원 무료
        벼메뚜기는 분류학적으로 메뚜기목(Orthoptera), 메뚜기과(Acrididae)에 속하는 곤충으로 작물에 피해를 주는 해충으로 인식하고 있지만 예로부터 단백질 보충을 위하여 채집하여 튀기거나 볶음요리 로 이용해 왔다. 벼메뚜기는 갈색거저리, 쌍별귀뚜라미 등과 함께 식품공전에 등록되어 있으나 1년 1세대로 가을철에 채집하여 이용하는 실정으로 공급확대에 한계가 있다. 최근 우리나라에서 벼메뚜기를 사육하고자 하는 농가와 다양한 용도로 가공을 통해 이용하려는 수요가 점차 증가하고 있으나 연중사육기술이 개발되지 않아 대량사육하는 농가가 거의 없는 실정이다. 이에 벼메뚜기의 연중대량사육기술 뿐만 아니라 인공사료 및 자동화 사육시설 개발에 따른 생산비 절감 기술 개발이 필요한 실정이다. 벼메뚜기의 먹이로는 여름작물로 옥수수, 수단그래스, 겨울작물로 밀, 보리 등의 볏과작물이 있으며 많은 양의 생엽과 발육에 적합한 작물의 선발 및 볏과작물의 통곡실 가루를 이용한 인공사료의 개발로 먹이공급 부족 시 15~20일 급여 가능하며, 벼메뚜기 사육시설로 단독형, 연결형, 절충형 등의 사육시설을 개발하여 연결형 사육시설의 수확량과 생존율이 가장 높았으며, 예취 급이 노동력이 단독형의 16% 소요되었다.
        10.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to identify key nations and bird species of conservation concern we described multinational collaborations as defined using network analysis linked by birds that are found in all nations in the network. We used network analysis to assess the patterns in bird occurrence for 10,422 bird inventories from 244 countries and territories. Nations that are important in multinational collaborations for bird conservation were assessed using the centrality measures, closeness and betweenness centrality. Countries important for the multinational collaboration of bird conservation were examined based on their centrality measures, which included closeness and betweenness centralities. Comparatively, the co-occurrence network was divided into four groups that reveal different biogeographical structures. A group with higher closeness centrality included countries in southern Africa and had the potential to affect species in many other countries. Birds in countries in Asia, Australia and the South Pacific that are important to the cohesiveness of the global network had a higher score of betweenness centrality. Countries that had higher numbers of bird species and more extensively distributed bird species had higher centrality scores; in these countries, birds may act as excellent indicators of trends in the co-occurrence bird network. For effective bird conservation in the world, much stronger coordination among countries is required. Bird co-occurrence patterns can provide a suitable and powerful framework for understanding the complexity of co-occurrence patterns and consequences for multinational collaborations on bird conservation.
        4,000원
        11.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Porcine spermatogonial stem cells (SSCs) prefer three-dimensional (3D) culture systems to 2D ones for the maintenance of self-renewal. Of the many 3D culture systems, agar-based hydrogels are candidates for supporting porcine SSC self-renewal, and there are various types of agar powder that can be used. In this study, we sought to identify an agar-based 3D hydrogel system that exhibited strong efficacy in the maintenance of porcine SSC self-renewal. First, 3D hydrogels with different mechanics were prepared with various concentrations of Bacto agar, lysogeny broth (LB) agar, and agarose powder, and the 3D hydrogel with the strongest alkaline phosphatase (AP) activity and greatest increase in colony size was identified for the different types of agar powder. Second, among the porcine SSCs cultured in the different 3D hydrogels, we analyzed the colony formation, morphology, and size; AP activity; and transcription and translation of porcine SSC-related genes, and these were compared to determine the optimal 3D hydrogel system for the maintenance of porcine SSC self-renewal. We found that 0.6% (w/v) Bacto agar-, 1% (w/v) LB agar-, and 0.2% (w/v) agarose-based 3D hydrogels showed the strongest maintenance of AP activity and the most pronounced increase in colony size in the culture of porcine SSCs. Moreover, among these hydrogels, the strongest transcription and translation of porcine SSC-related genes and largest colony size were detected in porcine SSCs cultured in the 0.2% (w/v) agarose-based 3D hydrogel, whereas there were no significant differences in colony formation and morphology. These results demonstrate that the 0.2% (w/v) agarose-based 3D hydrogel can be effectively used for the maintenance of porcine SSC self-renewal.
        4,000원
        14.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A total of nine Korean indigenous goats were used in a cross-over arrangement to give nine replicates per treatment, and they were housed individually assigned to 1 of 9 dietary treatments. Nine treatments were 0, 500, and 1000 ppm of quercetin supplementation in diets by mixing roughage and concentrate with different ratios (RC ratio) of 3:7 (RC 30), 5:5 (RC 50) and 7:3 (RC 70). Nutrient utilizations of dry matter, crude fat and NDF were not affected by neither RC ratio nor dietary quercetin (p>0.05), but the rate of crude protein and ADF increased in animals in RC 70 group regardless of quercetin supplementation (p<0.05). In addition, higher RC ratio increased (p<0.05) N retention and N retention rate. Total VFA, acetic acid, propionic acid, iso-butyric acid, butyric acid, iso-valeric acid and valeric acid contents were not affected (p>0.05) by dietary quercetin. Meanwhile, lower total cholesterol level exhibited in animals in RC 70 group compared to RC 30 or 50 groups, unrelated to dietary quercetin (p<0.05), however other plasma parameters were not influenced (p>0.05) by RC ratio and dietary quercetin. Our results indicated that both RC ratio and dietary quercetin may not directly affect the production indices and immune responses in Korean indigenous goat
        4,000원
        16.
        2016.10 구독 인증기관·개인회원 무료
        This studies was conducted to compare functional diversity of terrestrial arthropods in commercial apple orchards under conventional and organic practices. We collected terrestiral arthropods using pitfall traps in four conventional and seven organic apple orchards from April to October, 2012-2014. Sampled arthropods were identified at the species level and then classified three functional groups (detritivores, herbivores and beneficial arthropods included pollinators, parasitoids and predators). Biodiversity was analyzed with species richness, abundance and shannon index for each group and compared between conventional and organic orchards. In results, species richness of detritivores and benefical arthropods were higher in organic orchards than in conventional orchards (detritivores: t=-2.68, df=9, P=0.03; beneficial arthropods: t=-3.98, df=9, P=0.003). Organic orchards showed significant difference at abundance of beneficial arthropods (t=-3.33, df=9, P=0.008) and higher shannon index at detritivores (t=-2.36, df=9, P=0.04) than conventional orchards. However, all biodiversity indices of herbivores were not significantly different between conventional and organic orchards at 95% confidence level.
        17.
        2015.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in McConnachie et al. (2009), we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range 0.01 < z < 0.22. This large redshift sample shows that the interloper fraction in the McConnachie et al. (2009) compact group candidates is  42%. A secure sample of 332 compact groups includes 192 groups with four or more member galaxies and 140 groups with three members. The fraction of early-type galaxies in these compact groups is 62%, higher than for the original Hickson compact groups. The velocity dispersions of early- and late-type galaxies in compact groups change little with groupcentric radius; the radii sampled are less than 100 h−1 kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The physical properties of our sample compact groups include size, number density, velocity dispersion, and local environment; these properties slightly differ from those derived for the original Hickson compact groups and for the DPOSS II compact groups. Differences result from subtle differences in the way the group candidates were originally selected. The abundance of the compact groups changes little with redshift over the range covered by this sample. The approximate constancy of the abundance for this sample is a potential constraint on the evolution of compact groups on a few Gigayear timescale.
        5,200원
        19.
        2015.10 구독 인증기관·개인회원 무료
        Calepitrimerus vitis (Nalepa) is a grapevine pest and distributed worldwide. This study was conducted to identify grapevine damage related to density of C. vitis and to suggest an effective control time. The damaged flower buds displayed retarded growth and became dried up, and symptoms of damaged leaves such as malformed and bronzed leaves were observed. Flower cluster and leaves were collected and density of the grape rust mite were observed by using a washing and sieving method. The highest mean density (±SE) of C. vitis was found to be 672.6±112.9 per flower cluster with mid-level damage, and 450.1±66.5 per 2 leaves was found on the damaged leaves. These severe damage symptoms were observed in the early spring, and the density of the grape rust mite was significantly higher as 80 times in damaged vineyard than in the undamaged at the early growth stages of the grapevine. To determine the emergence time of the grape rust mite from lower part of a winter bud the ratio of density of C. vitis on upper-bud to lower-bud was observed. On 13 April 2015, 80% of the grape rust mites were observed on upper-bud where the mite could feed at the bud burst stage. Therefore, once the symptoms of damaged flower clusters and leaves are observed, acaricides should be sprayed before inflorescence emergence, and at the early growth stage between bud burst and leaf development in following year. This would allow the decrease of the density of C. vitis in early spring, and the progression of severe damage could be prevented.
        20.
        2015.04 구독 인증기관·개인회원 무료
        This studies was conducted to define community structure and diversity of epigeal spiders in apple orchards under different farming practices (organic and conventional). In 11 commercial apple orchards, epigeal spider community structure was investigated during 2012-2014 (3 orchards, 2012; 3 orchards, 2013, 5 orchards, 2014). Epigeal spiders were collected by pitfall traps from April to October, 2012 in Danyang-gun, Chungcheongbuk-do; 2013 in Muju-gun, Jeollabuk-do; 2014 in Cheongsong-gun and Uiseong-gun, Gyeongsangbuk-do, Korea. Sampled spiders were identified to the species level. Biodiversity was analyzed with species richness (total numbers of spider species), abundance (total numbers of individuals) and Shannon-Wiener diversity index (H΄) for each site and compared between organic and conventional orchards. In all regions, abundance of the spider communities were relatively higher in organic orchards than in conventional orchards. But, no significant difference in species richness and specie diversity (H΄) between organic and conventional orchards. Lycosidae was the most dominant family in all orchards regardless farming practices. However, Linyphiidae dominated in organic orchards only. The most dominant species were Pardosa laura (Lycosidae), Erigone koshiensis (Linyphiidae) in organic, Piratula procurvus (Lycosidae) in conventional orchards.
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