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        검색결과 136

        42.
        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
        44.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tin dioxide nanoparticles are prepared using a newly developed synthesis method of plasma-assisted electrolysis. A high voltage is applied to the tin metal plate to apply a high pressure and temperature to the synthesized oxide layer on the metal surface, producing nanoparticles in a low concentration of sulfuric acid. The particle size, morphology, and size distribution is controlled by the concentration of electrolytes and frequency of the power supply. The as-prepared powder of tin dioxide nanoparticles is used to fabricate a gas sensor to investigate the potential application. The particle-based gas sensor exhibits a short response and recovery time. There is sensitivity to the reduction gas for the gas flowing at rates of 50, 250, and 500 ppm of H2S gas.
        4,000원
        45.
        2017.10 구독 인증기관·개인회원 무료
        The spotted wing drosophila (SWD), Drosophila suzukii, is classified exotic quarantine pest in Australia and EU, soSWD-free must be supported by evidence of surveys and phytosanitary measures in exported host agricultural commoditiesin Korea. From a quarantine control point of view, SWD is importantly considered as model insect pest for exotic fruitflies (Bactrocera dorsalis) in Korea as well because of similarity in ecological cycles. In evaluations of ethyl formate(EF) only and combined cold treatment to kill eggs and larvae of SWD, the combined EF fumigation applied at LCt50%(50% killed lethal concentration X time) and cold treatement (5℃) for > 5 days showed the promise to new conceptfor eradicating quarantine pest and these could be helpful to pre-develop exotic fruit fly management in Korea.
        46.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Mesenchymal stem cells (MSCs) have been considered an alternative source of neuronal lineage cells, which are difficult to isolate from brain and expand in vitro. Previous studies have reported that MSCs expressing Nestin (Nestin+ MSCs), a neuronal stem/progenitor cell marker, exhibit increased transcriptional levels of neural development-related genes, indicating that Nestin+ MSCs may exert potential with neurogenic differentiation. Accordingly, we investigated the effects of the presence of Nestin+ MSCs in bone-marrow-derived primary cells (BMPCs) on enhanced neurogenic differentiation of BMPCs by identifying the presence of Nestin+ MSCs in uncultured and cultured BMPCs. The percentage of Nestin+ MSCs in BMPCs was measured per passage by double staining with Nestin and CD90, an MSC marker. The efficiency of neurogenic differentiation was compared among passages, revealing the highest and lowest yields of Nestin+ MSCs. The presence of Nestin+ MSCs was identified in BMPCs before in vitro culture, and the highest and lowest percentages of Nestin+ MSCs in BMPCs was observed at the third (P3) and fifth passages (P5). Moreover, significantly the higher efficiency of differentiation into neurons, oligodendrocyte precursor cells and astrocytes was detected in BMPCs at P3, compared with P5. In conclusion, these results demonstrate that neurogenic differentiation can be enhanced by increasing the proportion of Nestin+ MSCs in cultured BMPCs.
        4,000원
        48.
        2016.10 구독 인증기관·개인회원 무료
        In mature oocytes, maturation promoting factor (MPF) activity is playing important roles in arrest at M-phase and its continuous phenomenon, oocyte aging. In most mammals, metaphase II oocytes show high MPF activity and have been used as ooplasts in somatic cell nuclear transfer (SCNT). Caffeine has been found to regulate MPF activity in mammalian oocytes. Caffeine inhibits p34cdc2 phosphorylation and increases MPF activity. The present study investigated the effects of caffeine treatment during last 4 hours of in vitro maturation (IVM) on oocyte maturation and embryonic development after parthenogenesis (PA) and SCNT. The IVM medium was medium-199, 10% (v/v) PFF, cysteine, pyruvate, epidermal growth factor, kanamycin, insulin, and hormones. Immature oocytes were matured in IVM medium without or with 2.5 mM caffeine during the last 4 hours of IVM. The in vitro culture medium for embryonic development was porcine zygote medium-3 containing 0.3% (w/v) bovine serum albumin. Nuclear maturation (83.6–87.2%) and intraoocyte glutathione contents (0.9–1.0 pixels/oocyte) of oocytes were not influenced by the caffeine treatment. The membrane fusion of cell-cytoplast couplets (75.5–76.5%) and cleavage (85.4–86.2%) were also not altered by the caffeine treatment. However, caffeine-treated oocytes showed higher (P<0.05) blastocyst formation after SCNT (47.5 vs. 34.3%) than untreated oocytes. Our results demonstrate that caffeine treatment during last 4 hour of IVM improves the developmental competence of SCNT embryos probably by influencing MPF activity.
        49.
        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.
        50.
        2016.07 구독 인증기관 무료, 개인회원 유료
        Firms acquire customers using myriad forms of marketing media (Neslin & Shankar 2009), and different media strategies yield different results to the firms. Therefore, allocating media strategy given a firm’s spending raises important questions for managers. This is especially the case since the media landscape has changed dramatically, with new media channels incorporating online, mobile, and social media now being considered the mainstream. It is crucial to understand how each form of media influences consumers and how it operates alongside traditional media. Based on Stephen and Galak (2012), marketers distinguish earned media from paid media. Earned media is defined as media activity that a company does not directly generate, such as press mentions on the internet and online community posts in consumer-generated social media. On the other hand, paid media refers to the media activity which a company generates (for example, television, radio, print, and direct mail). It is common for firms to consider using earned media and paid media at the same time when developing marketing communication strategies. Despite the coexistence of paid and earned media channels, previous empirical findings focus either on paid media or earned media and suggest that these individually will increase a firm’s marketing outcomes. However, there is a lack of research that examines the question of whether the use of paid media and earned media at the same time is synergistic. The effects of a cross media synergy only focuses on the resource allocation within paid media (for example, TV–Radio (Edell & Keller 1989), TV–Magazine (Confer & McGlathery 1991), TV–Print (Dijkstra, Buijtels, & Van Raaij 2005), and TV, Radio, Print and Outdoor (Briggs, Krishnan, & Sheeran 2003)). Thus, by considering paid media and earned media concurrently, this study investigates whether the synergies between paid and earned media have a stronger effect on a firm’s long term profitability than the isolated effects of TV or word of mouth (WOM) alone. In addition, the research on earned media has focused on short-term outcomes such as customer actions (for example, website sign-ups) and sales growth, sales rank, cross-product sales, and ratings (Trusov, Bucklin, & Pauwels 2009; Li & Hitt 2008; Moe & Trusov 2011). Moreover, in the limited research on the relationship between earned media and long-term outcomes, the outcomes are restricted to those related to soft metrics of communication effectiveness (for example, attitude and brand awareness). Therefore, we use customer equity, which is regarded as a forward looking firm outcome variable, thereby enabling marketers to monitor and measure the long-term financial impact of marketing spending (Kumar & Shah 2015). Moreover, cross-media synergy can be accurately measured by customer equity, which incorporates both customer acquisition and retention. Based on Villanueva, Yoo, and Hassens (2008), customers acquired through paid media focus more on trials, whereas customers acquired through earned media provide the firm with more repeats. In other words, paid media plays a key role in the acquisition of customers, while, on the other hand, earned media increase the retention of customers. Thus, it is appropriate to measure the cross-media synergy with the customer equity (long term profitability) that can capture the customer acquisition and retention simultaneously. Regarding the long term impact of the firm’s media strategy, previous research has used the economic impact of traditional marketing channel (for example, television, radio, magazine or newspaper, advertisement, e-mail links, and direct mail) versus that of WOM (for example, links from Web sites, magazine, or newspaper articles, referrals from friends or colleagues, referrals from professional organizations or associations, and referrals from search engines) on customer equity. Traditional marketing had a stronger effect than WOM in the short term, while WOM is a quiet, gradual-impact, long lasting driver (Villanueva, Yoo, & Hassens 2008). This result can be attributed to the different characteristics of each media channel. Although earned media, including WOM, is not entirely controlled by the firm, earned media may be more likely to last longer for various reasons. One of the reasons for this phenomenon is that earned media has greater credibility than conventional marketing activities that are implemented by the firms, and is therefore more persuasive than conventional advertising (Brown & Reingen 1987, Villanueva, Yoo, & Hassens 2008). In other words, considering the impact of each type of media in itself, earned media is more effective in increasing long-term profitability. However, the interaction effect of earned and paid media has not been empirically tested yet. Thus, it is conceivable that a cross-media synergy (incorporating the implementation of earned media and paid media at the same time) will last longer than the implementation of each isolated media. As Armelini and Villanueva (2010) pointed out, earned media and paid media have complementary effects. For example, offline advertising increases website visitation by influencing consumer awareness, while online advertising directly leads to website traffic (Ilfeld & Winer 2002). The consumer buying process involves distinct stages such as awareness, consideration, and purchase (Lavidge & Stener 2000) and each media influences customer buying behavior in a different way. Hence, it enhances the effectiveness in terms of long-term profitability to utilize the cross-media effect properly. For example, in the car industry, 64 % new car buyers become aware of the features and benefits of a car by obtaining information online, even though they purchase their cars from an offline dealership (J.D. Power and Associates 2004). This finding implies that a firm’s implementation of both paid and earned media properly will maximize the customers’ arousal of the target brands. Furthermore, converging paid media and earned media is expected to proliferate the growth of a firm’s profitability, such as sales, revenue, and customer’s equity, at an exponential rate. For example, the effects of TV advertising execution can be enhanced by press mentions that a company does not directly generate; this is because press mentions support the credence of TV advertising. Inversely, since paid media activities reach the audience relatively more than WOM (due to the high audience penetration share), the online share of press mention can proliferate rapidly with the execution of paid media activities. Therefore, the interaction between earned media and paid media has a greater effect on customer equity than isolated media implementation. The impact of a media synergy has more positive effect and last longer than isolated media implementation (and our model is displayed in Fig. 1). We collect data on marketing efforts, word-of-mouth circumstance, and performance of a telecommunication company. Based on customer equity models and quarterly marketing and performance data, we first estimate the lifetime value of the newly acquired and existing customers. Thereafter, we determine the customer equity of the company over each period. We develop and employ a time-series model for examining the relationship between cross media efforts (paid media vs. earned media) and the estimated firm’s customer equity. Finally, we examine the synergistic effect of cross media on the firm’s long-term profitability.
        3,000원
        51.
        2015.12 구독 인증기관 무료, 개인회원 유료
        The aim of the present study was to investigate sex- and age-associated clinico-metabolic characteristics of urinary stone patients. A retrospective review was performed on data from 2,009 consecutive patients presenting with their first urinary stone episode between 2005 and 2013. Of the 2,009 patients, 1,426 (71.0%) satisfied the inclusion criteria and were enrolled in the study. Patients were grouped by age (<60, ≥60 years old) and sex. The medical history and 24 hr urinary chemistry results of each patient were obtained. The mean age of the 165 (11.6%) patients aged 60 or over was 65.5 ± 4.2 years. Body mass index was greater in elderly females than in younger females (p=0.031). After stratification by sex and age, lower urinary excretion of calcium and uric acid was a protective factor for both sexes among the elderly (p<0.05, each, respectively). Low urine pH was a common risk factor for both sexes among the elderly (p=0.013 in males, p=0.047 in females, respectively), whereas lower citrate excretion was a risk factor for only the elderly female group (p=0.004). With regard to urinary metabolic abnormalities, elderly females showed higher incidence of hypocitraturia compared to younger females (p=0.049). In conclusion, this study demonstrated the sex- and age-associated clinico-metabolic characteristics of urinary stone patients. Thus, it is important to tailor metabolic evaluation and medical prevention therapies for patient according to sex and gender characteristics.
        4,000원
        55.
        2015.06 구독 인증기관 무료, 개인회원 유료
        Dietary and lifestyle modifications are widely prescribed to prevent recurrence of urolithiasis, although little is known about the clinical and demographic factors associated with patient compliance and urinary metabolic changes. The present study assessed the clinical and demographic factors influencing compliance with a modified diet and lifestyle in first-time ureteric stone formers as well as determined the effects of compliance on urinary stone risk factors. We retrospectively reviewed the medical records of 53 patients presenting with ureteric calcium stones. Using a self-completed questionnaire, patients were classified according to compliance with seven recommendations for modifying diet and lifestyle into good compliance group (complied with ≥ three recommendations) and poor compliance group. Before (on a random diet) and after prescribing the modifications, 24 hour urine samples were collected from those in the good and poor compliance group. The stone size at presentation and initial treatment modality were closely associated with patient compliance (P=0.019, P=0.027, respectively). Citrate excretion significantly increased in the good compliance group after adopting modifications (P=0.012), whereas the poor compliance group did not show a statistically significant difference. Moreover, patients in the poor compliance group showed significantly increased urinary calcium excretion by the end of the study (P=0.040). After adjustments for age, sex, body mass index, and metabolic abnormality status, poor compliance was found to be an independent risk factor for persistence or development of hypocitraturia (OR: 3.885; 95% CI: 1.102~13.694; P=0.035). In conclusion, our results imply that patient education programs regarding diet and lifestyle should be tailored to the individual’s clinical and demographic characteristics.
        4,000원
        56.
        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.
        57.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was designed to evaluate the effect of bovine serum albumin (BSA) in a maturation medium on oocyte maturation and embryonic development in pigs. Immature pig oocytes were matured for 44 h in a medium supplemented with 0.4% (w/v) BSA, 0.1% (w/v) polyvinyl alcohol (PVA), or 10% (v/v) pig follicular fluid (PFF). After IVM, oocytes reached metaphase II stage were activated for parthenogenesis (PA) or used as cytoplasts for somatic cell nuclear transfer (SCNT). Nuclear maturation (89.5%, 90.7% and 91.3% for BSA, PVA and PFF, respectively) and intraoocyte glutathione contents (1.20, 1.16 and 1.00 pixels/oocyte for BSA, PVA and PFF, respectively) were not altered by the macromolecules added to maturation medium. IVM of oocytes in a medium containing BSA (21.4%) and PVA (20.7%) showed significantly lower blastocyst formation after PA than culture in medium with PFF (39.2%). After SCNT, oocytes matured in medium with BSA showed decreased embryonic development to the blastocyst stage (9.2%) compared to those matured in medium with PFF (28.9%), while 23.6% of SCNT oocytes matured in medium with PVA developed to the blastocyst stage. When the effect of BSA in a maturation medium during the first 22 h and the second 22 h of IVM in combination with PFF or PVA was examined, PVA-BSA showed a higher nuclear maturation (94.1%) than BSA-PFF (84.5%). However, there was no significant difference in the blastocyst formation among tested combinations (47.3, 52.2, 50.0, 44.4 and 49.0% for PFF-PFF, PFF-BSA, PVA-BSA, BSA-PVA and BSA-PFF, respectively). Our results demonstrate that BSA and PVA added to maturation medium can support oocyte maturation comparable to PFF-supplemented medium. However, maturation of oocytes in a BSA-containing medium decreases embryonic development after PA and SCNT when compared with the medium supplemented with PFF.
        4,000원
        58.
        2014.06 구독 인증기관 무료, 개인회원 유료
        Despite many researches related with in-vitro culture of porcine spematogonial stem cells (SSCs), adherent culture system widely used has shown a limitation in the maintenance of porcine SSC self-renewal. Therefore, in order to overcome this obstacle, suspension culture, which is known to have numerous advantage over adherent culture, was applied to the culture of porcine SSCs. Porcine SSCs retrieved from neonatal testes were suspension-cultured for 5 days or 20 days, and characteristics of suspension-cultured porcine SSCs including proliferation, alkaline phosphatase (AP) activity, and self-renewal-specific gene expression were investigated and compared with those of adherent-cul-tured porcine SSCs. As the results, the suspension-cultured porcine SSCs showed entirely non-proliferative and significantly higher rate of AP-positive cells and expression of self-renewal-specific genes than the adherent-cultured porcine SSCs. In addition, long-term culture of porcine SSCs in suspension condition induced significant decrease in the yield of AP staining-positive cells on post-day 10 of culture. These results showed that suspension culture was inappropriate to culture porcine SSCs, because the culture of porcine SSCs in suspension condition didn’t stimulate proliferation and maintain AP activity of porcine SSCs, regardless of culture periods.
        4,000원
        59.
        2014.04 구독 인증기관·개인회원 무료
        This study was conducted to investigate the community structure and species distribution of ground beetle assemblages in western part of Yeongwol-gun, Korea. Ground beetles were collected by pitfall traps from 9 study sites during July to October in 2013. A total of 30 species were identified from 4,439 collected ground beetles. Two dominant species, Synuchus nitidus (1,916 individuals) and Synuchus cycloderus (1,900 individuals) were occupied 85.8% of total. Interestingly, Pterostichus orientalis orientalis and Synuchus melantho were only collected in relative high altitude above 350 m, such as Beopheung-ri, Unhak-ri, and Yongseok-ri. Large-sized beetles, such as Damaster, Leptocarabus, and Carabus species, were generally more collected from Suju-myeon (Beopheung-ri and Unhak-ri) and Jucheon-myeon (Docheon-ri and Yongseok-ri) as well-conserved area, but not occurred in Yeongwol-eup and Hanbando-myeon, which forests may have lower habitat quality for these species. These differences also lead to increasing of dissimilarity among study sites, which were diverged into 3 groups at 53.0% of similarity. In particular, species composition of Samok-ri was significantly different at 8.2% of similarity because of difference in habitat characteristics as river side. This study has an important value to provide the fundamental information of inventory and monitoring in Yeongwol-gun. For detail mapping of species distribution in Yeongwol-gun, however, further studies are necessary, especially eastern parts of Yeongwol-gun.
        60.
        2014.04 구독 인증기관·개인회원 무료
        Epigeic spiders (Araneae) were surveyed in apple orchards under different farming practices (organic and conventional) in Muju-gun, Jeollabuk-do, Korea. The study was conducted from April to October in 2013 with 2 weeks interval using pitfall traps. Collected spiders were identified as 20 species of 6 families from 819 individuals in organic orchardⅠ, 19 species of 10 families from 759 individuals in orchardⅡ and 16 species of 8 families from 209 individuals in conventional orchard for from 1,787 captured spiders. Biodiversity was analyzed with species richness, abundance and Shannon diversity index (H΄). Species richness was statistically higher in organic orchard than in conventional orchard. Organic orchardⅡ comprised the greatest abundance followed by organic orchard and conventional. But species diversity was the highest in organic orchardⅡ, intermediate in conventional orchard and the lowest in orchardⅠ. Lycosidae was the most dominant family in all orchards regardless farming practices. However, Linyphiidae dominated in organic orchards only. The most dominant species were Erigone koshiensis (Linyphiidae) in organicⅠ, Pardosa laura (Lycosidae) in organicⅡ and Arctosa pungcheunensis (Lycosidae) in conventional orchard.
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