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        검색결과 37

        8.
        2017.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Like Hipparcos, Gaia is designed to give absolute parallaxes, independent of any astrophysical reference system. And indeed, Gaia’s internal zero-point error for parallaxes is likely to be smaller than any individual parallax error. Nevertheless, due in part to mechanical issues of unknown origin, there are many astrophysical questions for which the parallax zero-point error σ(π0) will be the fundamentally limiting constraint. These include the distance to the Large Magellanic Cloud and the Galactic Center. We show that by using the photometric parallax estimates for RR Lyrae stars (RRL) within 8kpc, via the ultra-precise infrared period-luminosity relation, one can independently determine a hyper-precise value for π0. Despite their paucity relative to bright quasars, we show that RRL are competitive due to their order-of-magnitude improved parallax precision for each individual object relative to bright quasars. We show that this method is mathematically robust and well-approximated by analytic formulae over a wide range of relevant distances.
        4,000원
        9.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We use ALLWISE data release W1- and W2-band epoch photometry collected by the Wide-Field Infrared Survey Explorer (WISE) to determine slopes of the period-luminosity relations for RR Lyrae stars in 15 globular clusters in the corresponding bands. We further combine these results with V- and K-band photometry of Galactic field RR Lyrae stars to determine the metallicity slopes of the log PF - [Fe/H]-MK, log PF - [Fe/H]-MW1, and log PF - [Fe/H]- MW2 period-metallicity-luminosity relations. We infer the zero points of these relations and determine the kinematical parameters of thick-disk and halo RR Lyraes via statistical parallax, and estimate the RR Lyrae-based distances to 18 Local-Group galaxies including the center of the Milky Way.
        4,000원
        10.
        2014.10 구독 인증기관·개인회원 무료
        In insect exoskeleton/cuticle, structural cuticular proteins (CPs) and the polysaccharide chitin are the major components of the procuticle. CPs are cross-linked by quinones or quinone methides produced by the laccase2 (Lac2)- mediated oxidation of N-acylcatechols. We reported that two major CPs, TcCPR27 and TcCPR18, belong to the CPR family that contain the RR-2 consensus motif (Rebers & Riddiford), are essential for formation and stabilization of the rigid cuticle of Tribolium castaneum adults. In this study, we characterized and investigated functions of the third most abundant protein, TcCP30, in extracts of elytra. TcCP30 cDNA encodes a protein with 171 amino acid residues containing a putative signal peptide. Unlike TcCPR27 and TcCPR18, TcCP30 mature protein lacks an RR motif, with a very unique amino composition, 36% Glu, 21% His, 20% Arg and 16% Gly. TcCP30 gene is highly expressed right before and after eclosion (in 5 d-old pupae and 0 d-old adults). Immunohistochemical studies revealed that TcCP30 protein was present in rigid cuticle such as elytra and ventral abdomen but not soft cuticle such as hindwings and dorsal abdomen of adult T. castaneum. Injection of dsRNA for TcCP30 into late instar larvae had no affect on larval and pupal growth and development. However, the subsequent pupal-adult molt, more than 50% adults were unable to shed their exuvium and died entrapped in their pupal cuticle. In addition, the resulting adults exhibited wrinkled, warped and split elytra. TcCP30-deficient adults could not fold their hindwings properly because probably due to the malformed elytra. These results indicate that TcCP30 is critical for formation of rigid adult cuticle as well as development and growth of T. castaneum.
        12.
        2013.10 구독 인증기관·개인회원 무료
        Cuticular proteins (CPs) and the polysaccharide chitin are the major components of the exo- and endocuticular layers or procuticle. CPs contain a conserved sequence known as the Rebers & Riddiford (R&R) motif, which may function as a chitin-binding domain that helps to coordinate the interaction between chitin fibers and the protein network. We identified two highly abundant RR-2 CPs, TcCPR18 and TcCPR27, in protein samples extracted from elytra (rigid cuticle) of Tribolium castaneum adults and determined that these two CPs are required for rigid cuticle morphology. In this study, we identified the third most abundant protein (TcCP30) extracted from the elytra, and cloned a full-length cDNA. It encodes a very unusual 171 amino acid residue protein of which 36% of the residues of the mature protein are Glu, 21% are His, 19% are Arg, and 16% are Gly, organized in a regular pattern but not R&R consensus motif. TcCPR18 and TcCPR27 genes are expressed at 4 d-old pupae, while TcCP30 is highly expressed at 5 d-old pupae (last pupal stage) and 0 d-old adults. Immunohistochemical studies revealed the presence of TcCP30 in rigid adult cuticle (e.g. elytron, pronotum and ventral abdomen) but not soft cuticle (e.g. hindwing and dorsal abdomen). Injection of dsRNA for TcCP30 into late instar larvae had no affect on larval and pupal growth and development. The subsequent pupal-adult molt, however, more than 50% adults were unable to shed their exuvium and died. In addition, the resulting adults exhibited wrinkled, warped and split elytra. TcCP30-deficient adults could not fold their hindwings properly. These results indicate that TcCP30 may play critical roles in rigid adult cuticle formation, development and insect growth and survival. This work was supported by NRF (NRF-2012R1A2A1A01006467).
        13.
        2013.10 구독 인증기관·개인회원 무료
        Insects have a protective exoskeleton consisted with cuticle to adapt various environments and pathogens. Insect cuticle mainly composed of the polysaccharide chitin and numerous of cuticular proteins (CPs). CPs are important for insect cuticle formation, development, and growth because it produces proper combination of mechanical and physical properties of cuticle depend on the regions of an exoskeleton. The largest family of CPs contains a 28-residue motif known as the Rebers-Riddiford (R&R) consensus sequence. When sequences containing the R&R consensus are aligned, they fall into three groups based on sequence similarity, and these groups tend to correlate with the type of cuticle (soft or hard) from which the proteins are derived. Proteins with the RR-1 motif have been found primarily in soft cuticle, whereas many proteins from rigid cuticle have an extended region of similarity called RR-2. We recently reportedthat two major CPs, TcCPR18 and TcCPR27 belong to RR-2, are essential for formation of highly sclerotized modified-forewings (elytra) of a beetle. In this study, we performed functional genomics of TcCPR4, which encodes RR-1 motif. The transcript levels of TcCPR4 drastically increased in 3 d-old pupae at when adult cuticle synthesis appears to be begun. Immunohistochemical studies revealed that TcCPR4 protein was detected in the rigid cuticle of elyton and ventral abdomen but not in the flexible cuticle of hindwing and dorsal abdomen of T. castaneum adult. Furthermore, TcCPR4 protein was specifically present at basal side of the procuticle (near the epidermal cells) and vertical canals, whereas TcCPR27 protein was found entire procuticle. Injection of double-stranded RNA of TcCPR4 (dsTcCPR4) into late instar larvae had no effect on development and any types of molting such as larval-larval, larval-pupal or pupal-adult. Interestingly, depletion of both TcCPR4 and TcCPR27 transcripts could rescue the elytral cuticle defect and mortality produced by injection of dsTcCPR27 alone. Transmission electron microscopy analysis revealed that depletion of TcCPR4 had abnormal vertical canals in rigid adult cuticle while dsTcCPR27 injection showed less electron-dense-horizontal laminae and vertical canals. Surprisingly, co-injection of dsRNA for TcCPR4 and TcCPR27 exhibited more severe cuticle defect with thinner elytral cuticle and abnormal vertical canals and chtin laminae compared to those from insects treated with dsRNA for each gene. These results suggest that TcCPR4 as a RR-1 is essential structural component in the rigid cuticle of T. castaneum adult.
        14.
        2012.11 구독 인증기관 무료, 개인회원 유료
        The paper reviews properties of hypothesis decision approaches using rejection region and significance probability. The study also presents the guidelines for quality practioners to implement most useful hypothesis testing techniques such as RR(Rejection Region) approach and P-Value approach.
        3,000원
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