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        검색결과 75

        41.
        2016.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Microlensing is generally thought to probe planetary systems only out to a few Einstein radii. Microlensing events generated by bound planets beyond about 10 Einstein radii generally do not yield any trace of their hosts, and so would be classified as free floating planets (FFPs). I show that it is already possible, using adaptive optics (AO), to constrain the presence of potential hosts to FFP candidates at separations comparable to the Oort Cloud. With next-generation telescopes, planets at Kuiper-Belt separations can be probed. Next generation telescopes will also permit routine vetting for all FFP candidates, simply by obtaining second epochs 4--8 years after the event.At present, the search for such hosts is restricted to within the ``confusion limit'' of θconfus ∼ 0.25 〃, but future WFIRST (Wide Field Infrared Survey Telescope) observations will allow one to probe beyond this confusion limit as well.
        3,000원
        43.
        2016.04 구독 인증기관·개인회원 무료
        The lesser paper wasp, Parapolybia varia, belongs to large subfamily Polistinae and is distributed in Middle East, the Indo-Papuan region and East Asia. P. varia is known to become aggressive when disturbed for defending their colonies, resulting in fatal envenomation. Vespid chemotactic peptide (VCP) and vespakinin have recently been determined to be the top two genes most abundantly transcribed in venom glands of P. varia. To investigate the pharmacological and toxicological properties of VCP and vespakinin, their antitumor, antimicrobial, and cytotoxic activities were evaluated. VCP exhibited a significantly high antitumor activity against ovarian tumor cell SK-OV-3 at 100 M. VCP also showed higher hemolytic activity than vespakinin. Antimicrobial activity was only observed with VCP against yeast Candida albicans at 1 mM. Since VCP showed a relatively low hemolytic activity but a considerable level of antitumor activity, it has further merits to be exploited as a potential antitumor agent with reduced side effects on normal cells.
        44.
        2016.04 구독 인증기관·개인회원 무료
        Twelve Lamiaceae plant essential oils (EOs) and their components were evaluated for their fumigant and contact toxicities. Inhibition of AChE by the major components of active EOs was also assessed. Strong fumigant toxicity was observed from EOs of Mentha piperita and Perilla frutescens. Menthone and menthol, and perilla aldehyde were identified as major components of the above two EOs, respectively. The LC50 (mg/L) values of M. piperita, P. frutescens, menthone, menthol and perilla aldehyde were 3.87, 2.44, 5.76, 1.88, and 0.99 against male, and 4.10, 3.31, 5.13, 1.94, and 1.15 against female, respectively. Strong contact toxicity was observed from the EOs of Satureja montana and Thymus zygis. Thymol and carvacrol were major components of these two EOs. The LD50 (μg/fly) values for contact toxicity of S. montana, T. zygis, thymol and carvacrol were 2.95, 2.93, 1.63, and 1.30 for male, and 4.59, 5.09, 2.68, and 2.60 for female, respectively. Among the five major components, perilla aldehyde showed most active inhibition activity against AChE of both sexes of SWD.
        45.
        2016.04 구독 인증기관·개인회원 무료
        Drosophila suzukii is an economically important pest of fruit in America and Europe as well as in Asia. Sparassol (1) and methyl orsellinate (2) are produced by Sparassis cripta and S. latifolia during culture. Fumigant and contact toxicities of synthetic sparassol (1) methyl orsellinate (2) and methyl 2,4-dimethoxy-6-methylbenzoate (DMB; 3) were investigated. The possible mode of action of the compounds was pursued by assessing their inhibition activities against acetylcholinesterase (AChE) and glutathione S-transferase (GST). Little or no fumigant activity was observed from tested compounds. In contact toxicity activity, LD50 (μg/fly) values are 5.29, 1.18, 0.02 for male, and 11.14, 2.27, 0.05 for female, respectively. In enzyme inhibition assay, DMB (3) which easily synthesized from sparassol could be an alternative agent for controlling insect pest. In addition, Sparassis species could be an industrial resource of sparassol.
        46.
        2016.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Euclid, which is primarily a dark-energy/cosmology mission, may have a microlensing component, consisting of perhaps four dedicated one-month campaigns aimed at the Galactic bulge. We show that such a program would yield excellent auxilliary science, including asteroseismology detections for about 100 000 giant stars, and detection of about 1000 Kuiper Belt Objects (KBOs), down to 2–2.5 mag below the observed break in the KBO luminosity function at I ∼ 26. For the 400 KBOs below the break, Euclid will measure accurate orbits, with fractional period errors . 2.5%.
        4,000원
        47.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Checks are best considered as a (visible) sub-set of grids, and each check consists of two assemblies of parallel lines, one superimposed on the other at ninety degrees. In the conventional textile context, one assembly of parallel yarns is superimposed on another at ninety degrees. These parallel lines caused by the yarns remain visually apparent in the finished composition. Commonly, checks are considered simply as a variety of woven textile and Scottish clan tartans, or plaids (common terminology for tartans in the USA), famously display a checked feature, using differently colored yarns in woven-textile form. Often the sequence of colours and the numbers of yarns used is equal in both warp and weft directions. Where this is the case, the tartan may be considered to be ‘balanced’ or ‘regular’, with the component yarns creating square units repeating across and down the fabric. Thus in balanced tartans, lengthways components have identical ordering, colouring and measured width to those used widthways. Meanwhile an unbalanced check lacks one or more of these attributes. This paper explores further the nature of Scottish clan tartans, using data collected from collections of rare tartans held at ULITA – An Archive of International Textiles at the University of Leeds.
        4,000원
        49.
        2015.10 구독 인증기관·개인회원 무료
        Vespa crabro and V. analis are social hornet species commonly found in Asia, including Korea. Mastoparan is one of the major venom peptides of these two hornets but its amino acid sequence defers substantially. To examine the differences in the potential toxicity and bioactivity of mastoparans between these two social hornets, differential toxicological and pharmacological activities of synthesized mastoparan were investigated. V. analis mastoparan showed a 7-fold higher hemolytic activity, suggesting its higher cytotoxic potential compared with V. crabro mastoparan. Mastoparans from both hornet species exhibited similar levels of antimicrobial activities against Staphylococcus aureus and Botrytis cinerea, whereas the mastoparan from V. analis showed more potent antimicrobial activities against Escherichia coli and Candida albicans. Nevertheless, the antimicrobial activities of mastoparans of V. crabro and V. analis were relatively lower compared with those of other wasps. Both mastoparans also exhibited some levels of antitumor activity but the activity was significantly higher in V. analis mastoparan. In summary, the hemolytic, antimicrobial, and antitumor activities of synthesized V. analis mastoparan were higher than those of V. crabro mastoparan. These differential bioactivities are likely due to the amino acid sequence differences in the mature peptides. In particular, the additional Lys residue present in V. analis mastoparan may contribute to the higher levels of bioactivity as proposed by secondary structure prediction.
        50.
        2015.10 구독 인증기관·개인회원 무료
        The hornets Vespa crabro and V. analis are widely distributed in Asia and are known to be aggressive when disturbed, resulting in frequent stinging accidents. To investigate the differences in venom properties and toxicities between these two hornets, the transcriptomic profiles of venom glands, in conjunction with the venom components, were analyzed and compared. A total of 35 venom-specific genes were identified in both venom gland transcriptomes, but their transcriptional profiles were different between V. crabro and V. analis. In addition, the major venom components were identified and confirmed by mass spectroscopy. Prepromastoparan, vespid chemotactic precursor and vespakinin were the top three genes most prevalently transcribed in the venom gland of V. crabro, and their transcription rates were 112-, 16- and 161-fold higher, respectively, compared with those in V. analis, as judged by FPKM values. In the venom gland of V. analis, however, vespid chemotactic precursor was the most abundantly transcribed gene, followed by premastoparan and vespakinin. In general, most major venom genes were more abundantly expressed in V. crabro, whereas some minor venom genes exhibited higher transcription rates in V. analis, including muscle LIM protein, troponin, paramyosin, calponin, etc. Our findings reveal that the overall venom components of V. crabro and V. analis are similar, but that their expression profiles and levels are considerably different. The comparison of venom gland transcriptomes suggests that V. crabro likely produces venom with more highly enriched major venom components, which has potentially higher toxicity compared with V. analis venom.
        51.
        2015.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        WFIRST microlensing observations will return high-precision parallaxes, σ(π) . 0.3 μas, for the roughly 1 million stars with H < 14 in its 2.8 deg2 field toward the Galactic bulge. Combined with its 40,000 epochs of high precision photometry (∼ 0.7 mmag at Hvega = 14 and ∼ 0.1 mmag at H = 8), this will yield a wealth of asteroseismic data of giant stars, primarily in the Galactic bulge but including a substantial fraction of disk stars at all Galactocentric radii interior to the Sun. For brighter stars, the astrometric data will yield an external check on the radii derived from the two asteroseismic parameters, the large-frequency separation hνnli and the frequency of maximum oscillation power νmax, while for the fainter ones, it will enable a mass measurement from the single measurable asteroseismic parameter νmax. Simulations based on Kepler data indicate that WFIRST will be capable of detecting oscillations in stars from slightly less luminous than the red clump to the tip of the red giant branch, yielding roughly 1 million detections.
        4,300원
        52.
        2015.04 구독 인증기관·개인회원 무료
        Vespa crabro is a cosmopolitan social wasp species whereas Vespa analis is commonly found in Asia. Both species are widely distributed in Korea and known to be aggressive when disturbed, resulting in frequent sting accidents. Although major venom components of well known Vespa wasps have been reported, no comparative transcriptomic analysis of venom gland between V. crabro and V. analis has been conducted to date. To investigate the differences in venom properties between these two wasps, total RNA was extracted from each venom gland and used for RNA-sequencing. A total of 31 venom-specific genes were identified in both venom gland transcriptomes but their expression profiles were different between V. crabro and V. analis. Venom allergen 5, premastoparan A and phospholipase A were the top three genes that were most prevalently transcribed in the venom gland of V. crabro, and their transcription rates were 902-, 112- and 4164-fold higher compared with V. analis, respectively, as judged by FPKM values. Their differential transcription profiles were confirmed by quantitative real-time PCR. In the venom gland of V. analis, however, premastoparan A was most abundantly transcribed gene, followed by calponin and tropomysin. In general, most venom-specific genes were more abundantly expressed in V. crabro but some genes exhibited higher transcription rates in V. analis, including muscle LIM protein, troponin, paramyosin, calponin, etc. Our findings suggest that V. crabro produce venom with much more enriched venom components, thereby with higher toxicity compared with V. analis.
        53.
        2014.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        I show that the WFIRST microlensing survey will enable detection and precision orbit determination of Kuiper Belt Objects (KBOs) down to Hvega = 28.2 over an effective area of ∼ 17 deg2. Typical fractional period errors will be ∼ 1.5% × 100.4(H−28.2) with similar errors in other parameters for roughly 5000 KBOs. Binary companions to detected KBOs can be detected to even fainter limits, Hvega = 29, corresponding to R ∼ 30.5 and effective diameters D ∼ 7 km. For KBOs H ∼ 23, binary companions can be found with separations down to 10 mas. This will provide an unprecedented probe of orbital resonance and KBO mass measurements. More than a thousand stellar occultations by KBOs can be combined to determine the mean size as a function of KBO magnitude down to H ∼ 25. Current ground-based microlensing surveys can make a significant start on finding and characterizing KBOs using existing and soon-to-be-acquired data.
        4,500원
        54.
        2014.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        One-dimensional (1-D) microlens parallaxes can be combined with heliocentric lens-source relative proper motion measurements to derive the lens mass and distance, as suggested by Ghosh et al. (2004). Here I present the first mathematical anlysis of this procedure, which I show can be represented as a quadratic equation. Hence, it is formally subject to a two-fold degeneracy. I show that this degeneracy can be broken in many cases using the relatively crude 2-D parallax information that is often available for microlensing events. I also develop an explicit formula for the region of parameter space where it is more difficult to break this degeneracy. Although no mass/distance measurements have yet been made using this technique, it is likely to become quite common over the next decade.
        3,000원
        55.
        2014.12 구독 인증기관 무료, 개인회원 유료
        With the highest suicide rate among OECD countries, South Korea is facing serious problems regarding social integration. While many previous studies have focused on the meso or micro level factors responsible for suicide, this paper will discuss macro levelchanges affecting modes of solidarity within Korean society. In the 1950s and 1960s, Koreans shared the common goal of rebuilding the nation. Following that, the 1970s and1980s can be viewed as the era of democratization, during which the development discourse and theses on equality predominated in equal parts. Since the mid-1990s, however, South Korea has been facing an unprecedented level of uncertainty. Each shiftin the societal climate has created a different way for citizens to feel a sense of collectivebelonging. It is argued that as we enter an era where individual isolation can only get worse, research on suicide and on social integration in general should take into consideration national historical trends and their impact on individuals.
        4,600원
        56.
        2014.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        I show that the standard microlensing technique to measure the angular radius of a star using color/surface-brightness relations can be inverted, via late-time proper motion measurements, to calibrate these relations. The method is especially useful for very metal-rich stars because such stars are in short supply in the solar neighborhood where other methods are most effective, but very abundant in Galactic bulge microlensing fields. I provide a list of eight spectroscopically identified high-metallicity bulge stars with the requisite finite-source effects, seven of which will be suitable calibrators when the Giant Magellan Telescope comes on line. Many more such sources can be extracted from current and future microlensing surveys.
        4,000원
        57.
        2013.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        On December 29, 2011, the National Assembly of the Republic of Korea passed the Law on the Status and Treatment of Refugees, which went into effect on July 1, 2013. The law was the culmination of years of effort by the government, NGOs, UNHCR and the lawmakers. It has been widely praised by civil society groups in Korea. However, there has been little critical analysis of its provisions whether it will truly be a successful legislation. This research critically evaluates whether the new law is likely to promote Korean compliance with international legal standards, namely, the 1951 Refugee Convention and major human rights treaties. It finds that while the law represents a significant improvement over current practices, it possesses problematic provisions related to detention, refugee determination, economic and social rights of asylum-seekers, and the treatment of recognized refugees. This essay will conclude by highlighting four outstanding implementation questions that could impact compliance with international standards.
        5,100원
        58.
        2013.10 구독 인증기관·개인회원 무료
        The aim of this study is to analyze the functional activity of an endo-β-1, 4-glucanase from the wood dwelling lower termite Coptotermes gestroi. Full length cDNA sequences of the endo-β-1,4-glucanase were obtained by primer walking in conjunction with Rapid Amplification cDNA Ends. With the obtained full length sequences, primers for amplifying open reading frame (ORF) excluding the signal peptide and glycophosphatidylinositol anchor were designed. Amplified endo-β-1,4-glucanase fragment was cloned and expressed using pET30(+) expression vector in BL21 E.coli strain. Expression of endo-β-1,4-glucanase was confirmed by Western blotting and the result revealed that only full ORF was expressed. The cellulase activity of protein preparations from the induced and non-induced cells was analyzed with Congo Red assay with the cellulase from Aspergillus niger (Sigma Aldrich) as a positive control. The activity of C. gestroi endo-β-1,4-glucanase was significantly higher than those observed in the positive control and the enzyme preparation from non-induced cells. Therefore, this study confirmed that C. gestroi endo-β-1,4-glucanase had a function of cellulose hydrolysis.
        59.
        2013.04 구독 인증기관·개인회원 무료
        To search for a variety of cellulase genes from termites with different habitats consuming different foods, we collected three species (Neotermes spp., Odontotermes spp., Macrotermes spp.) from the wood and one species (Nasutitermes spp.) from the cow dung. Total RNA was isolated both from alimentary track tissues containing paunch and from other tissues, and used for the suppression subtractive hybridization (SSH). The resulting EST libraries were sequenced and searched by BLAST to identify cellulase genes. A total of 16 cellulase genes were found from the wood-dwelling termites whereas 4 cellulase genes from the cow dung-dwelling termites. Endo-beta-1,4-glucanase and beta-glucosidase were identified as the most abundant cellulase from the wood-dwelling termites and cow dung-dwelling termites, respectively. This finding suggests that cellulase profiles are significantly different depending on the termite’s habitat and food. In addition, we analyzed phylogenetic relationships among the cellulase genes along with other cellulase genes reported to date. All cellulase genes appeared to be originated from endosymbioants without any hint of horizontal gene transfer. Functional expression of endo-beta-1,4-glucanase using a baculovirus expression system is in progress to characterize its enzymatic properties.
        60.
        2012.10 구독 인증기관·개인회원 무료
        Many previous ecological studies on three major bacterial symbionts and a newly discovered symbiont PAXS (pea aphid X-type symbiont) in the pea aphid Acrythosiphon pisum have shown that these symbionts are associated with the expression of a variety of host phenotypes, including resistance to parasitoid Aphidius ervi and tolerance to heat stress. The principal role of all four symbionts “Candidatus Serratia symbiotica”, “Candidatus Hamiltonella defensa”, “Candidatus Regiella insecticola”, and PAXS is to protect aphids against abiotic stress by preserving the cells in which most of symbionts dwell and by reducing the rate of parasitism. In this experiment, we detected endosymbionts from four aphid clones by means of genomic DNA extraction, PCR with gene specific primer, and restriction enzyme cutting. The patterns of PCR and restriction enzyme cutting were all identical in the four aphid clones. In order to specifically identify the endosymbiont, we searched the sequences using BLAST. The BLAST search revealed that nucleotide sequences of the symbiont were 98% identical to Serratia entomophil. S. entomophil is also known to provide tolerance to heat stress, resistance to parasitoid wasps, and restoration of reproduction in aphids, suggesting its role in host protection.
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