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        검색결과 1,093

        361.
        2011.10 구독 인증기관·개인회원 무료
        The composition of culture media is a key element in the process of in vitro embryo production. With the development of defined culture media, many components that are present in trace amounts in follicular fluid and serum have been excluded from the in vitro embryo production system. Among these are hormones, which have important regulatory roles in growth, metabolism and differentiation and are known to be present in follicular fluid, serum and the female reproductive tract. We have investigated the effects of supplementation of in vitro maturation and/or culture medium with testosterone (T), androstenedione (A4) and thyroid hormones (TH) on bovine in vitro embryo production and the mechanisms of action of TH in developing embryos. Our results show that testosterone, but not androstenedione or thyroid hormone supplementation increased cleavage rates. None of the treatments significantly altered the sex ratio. Addition of thyroid hormones, T3 and T4, to the in vitro culture media resulted in a significant increase in the rate of development to the blastocyst stage. In addition, blastocysts from the T3/T4 treated groups had higher cell number and lower rates of apoptosis. We have confirmed the expression of mRNAs for both Thyroid hormone receptor α and β (TR α and β) in cumulus‐oocyte‐complexes, oocytes, and in both treated and control blastocyst. Quantitatively, the expression of TR mRNA was higher in the treated embryos but the difference was not statistically significant. TR proteins were detectable in blastocysts of both groups with a difference in the distribution pattern. TH treated embryos had peri‐nuclear concentration of TR while in control embryos it was homogenously distributed in the cytoplasm. Preliminary studies of inhibition of TR α and β by siRNA knockdown by micro injection at the zygote stage show a drastic reduction in development suggesting that TH play an essential role in embryo development. They appear to mediate this effect by their receptors, TR α and β. Overall the results show that the presence of hormones in maturation and the culture medium can alter the outcome of in vitro embryo production and highlight the significance of biological components missing from in defined embryo culture media.
        362.
        2011.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ovulation synchronization (ovsynch) has proved to increase the number of insemination in cattle by overcoming the problems of heat detection. The aim of this study was to do ovsynch in water buffaloes where heat detection is a major reproductive problem and to determine the conception rates after timed artificial insemination (TAI). Twenty cyclic buffaloes at 60 days postpartum were selected by examining 24 unobserved estrus buffaloes based on milk progesterone assay (progesterone concentration 1.0 ng/ml) from the Mymensingh district of Bangladesh. Ovsynch treatment regimen was started irrespective of the stage of estrous cycle. Gonadorelin (500 ) was injected intramuscularly at Day 0 followed by Alfaprostol (8 mg) at Day 7. A second injection of Gonadorelin was given at Day 9 and TAI was done with frozen semen from Mediterranean buffalo bulls at 16~20 hours of the second Gonadorelin injection. Milk progesterone ELISA at Day 10~12 post AI confirmed ovulation in 16 out of 20 (80%) buffaloes (progesterone concentration 1.0 ng/ml). High progesterone concentration ( 1.0 ng/ml) at Day 10~12 and Day 22~24 of AI showed pregnancy in six out of 20 (30%) buffaloes. Pregnancy was further confirmed by ultrasonography at Day 40 in these six buffaloes. In conclusion, ovsynch followed by TAI could be applied in cyclic buffaloes for overcoming the estrus detection problems; however, more studies are needed to increase the conception rate.
        4,000원
        363.
        2011.06 구독 인증기관 무료, 개인회원 유료
        The development of informatization impacts all sectors, including agriculture. Agricultural informatization builds the knowledge linkage structures of agricultural innovation systems globally. This study investigated the global knowledge linkage structures in agricultural innovation pertinent to information technology (IT) for agricultural research and development (R&D) investments and activities. We explored the longitudinal trend of systemness within the networked research relationships in the triple helix (TH) of the university, industry and government (UIG). We collected data from publications in the Science Citation Index (SCI), the Social Sciences Citation Index (SSCI), and the Arts and Humanities Citation Index (A&HCI) to analyze the TH network dynamics. We also performed a scientometrics analysis to quantitatively identify the knowledge and insights of global agricultural innovation structures. These results could be informative for individual countries. Our findings reveal that the global knowledge linkage structures in the agricultural sector that are pertinent to IT fluctuate widely and fail to increase the capacity of agricultural innovation research due to a neglect of the network effects of the TH dynamics of UIG.
        4,800원
        367.
        2011.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the results of our high resolution optical spectroscopic monitoring campaign (⋋ = 3800 ~ 8800 Å, R = 30000 - 45000) of the new FU Orionis-type object HBC 722. We observed HBC 722 with the BOES 1.8-m telescope between November 26 and December 29, 2010, and FU Orionis itself on January 26, 2011. We detect a number of previously unreported high-resolution K I and Ca II lines beyond 7500 Å. We resolve the Hα and Ca II line profiles into three velocity components, which we attribute to both disk and outflow. The increased accretion during outburst can heat the disk to produce the relatively narrow absorption feature and launch outflows appearing as high velocity blue and red-shifted broad features.
        4,000원
        368.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates the effect of filler content (wt%), presence of interphase and agglomerates on the effective Young's modulus of polypropylene (PP) based nanocomposites reinforced with exfoliated graphite nanoplatelets (xGnPTM) and carbon nanotubes (CNTs). The Young's modulus of the composites is determined using tensile testing based on ASTM D638. The reinforcement/polymer interphase is characterized in terms of width and mechanical properties using atomic force microscopy which is also used to investigate the presence and size of agglomerates. It is found that the interphase has an average width of ~30 nm and modulus in the range of 5 to 12 GPa. The Halpin-Tsai micromechanical model is modified to account for the effect of interphase and filler agglomerates and the model predictions for the effective modulus of the composites are compared to the experimental data. The presented results highlight the need of considering various experimentally observed filler characteristics such as agglomerate size and aspect ratio and presence and properties of interphase in the micromechanical models in order to develop better design tools to fabricate multifunctional polymer nanocomposites with engineered properties.
        4,000원
        369.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The effects of geometrical parameters on mechanical properties of graphite-vinylester nanocomposites and their constituents(matrix, reinforcement and interface) are studied using molecular dynamics (MD) simulations. Young’s modulii of 1.3TPa and1.16TPa are obtained for graphene layer and for graphite layers respectively. Interfacial shear strength resulting from themolecular dynamic (MD) simulations for graphene-vinylester is found to be 256MPa compared to 126MPa for graphite-vinylester. MD simulations prove that exfoliation improves mechanical properties of graphite nanoplatelet vinylesternanocomposites. Also, the effects of bromination on the mechanical properties of vinylester and interfacial strength of thegraphene–brominated vinylester nanocomposites are investigated. MD simulation revealed that, although there is minimal effectof bromination on mechanical properties of pure vinylester, bromination tends to enhance interfacial shear strength betweengraphite–brominated vinylester/graphene-brominated vinylester in a considerable magnitude.
        4,000원
        370.
        2010.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Few would dispute that good health is fundamental to a full and active life. It is the key to wealth and prosperity. Good health contributes directly to economic growth while poor health drives poverty. The right to health is considered directly in many international instruments including the World Health Organization. Every single country in the world is now a member of at least one of the many international instruments where health is treated as a human right. Sound health is a precondition to enjoy right to live peaceful. This right to health is guaranteed by the Constitution of the People’s Republic of Bangladesh. If anybody in Bangladesh is deprived of enjoying his life then he can go to the court in order enforce his right. This paper aims at giving an overview of legal and regulatory framework of different international legal instruments and national laws of Bangladesh relating to healthcare and shares the response of Bangladesh Government in relation to the framework.
        6,600원
        374.
        2010.10 구독 인증기관·개인회원 무료
        DNA barcoding uses a 650 bp segment of the mitochondrial cytochrome c oxidase I (COI) gene as the basis for an identification system for members of the animal kingdom and some other groups of eukaryotes. PCR amplification of the barcode region is a key step in the analytical chain, but it sometimes fails because of a lack of homology between the standard primer sets and target DNA. Two forward PCR primers were developed following analysis of all known arthropod mitochondrial genome arrangements and sequence alignment of the tRNA-W gene which was usually located within 200 bp upstream of the COI gene. These two primers were combined with a standard reverse primer (LepR1) to produce a cocktail which generated a barcode amplicon from 125 of 141 species that included representatives of 121 different families of Hexapoda. High quality sequences were recovered from 79% of the species including groups, such as scale insects, that invariably fail to amplify with standard primers. The current results show that primers designed to bind to highly conserved gene regions upstream of COI will aid the amplification of this gene region in species where standard primers fail and provide valuable information to design a primer for problem groups.
        375.
        2010.10 구독 인증기관·개인회원 무료
        Although DNA barcode coverage has grown rapidly for many insect orders, there are some groups, such as scale insects, where sequence recovery has been difficult. However, using a recently developed primer set, we recovered barcode records from 373 specimens, providing coverage for 75 species from 31 genera in two families. Overall success was >90% for mealybugs and >80% for armored scale species. The G·C content was very low in most species, averaging just 16.3%. Sequence divergences (K2P) between congeneric species averaged 10.7%, while intraspecific divergences averaged 0.97%. However, the latter value was inflated by high intra-specific divergence in nine taxa, cases that may indicate species overlooked by current taxonomic treatments. Our study establishes the feasibility of developing a comprehensive barcode library for scale insects and indicates that its construction will both create an effective system for identifying scale insects and reveal taxonomic situations worthy of deeper analysis.
        377.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,000원
        379.
        2010.06 구독 인증기관 무료, 개인회원 유료
        In this knowledge based society, the debate on ICT has permanently shifted from ʻwhyʼ ICT for development, to ʻhowʼ comprehensive and holistic ICT policies can unleash human potential and enhance peopleʼs capabilities to improve their lives. Recognizing this untapped potential and development strategies incorporating ICT are being increasingly promoted and launched across the developing countries. While the potential advantages of ICT for development are enormous in developed countries, national policies of developing countries are yet to adequately reflect truly comprehensive and integrated strategies for harnessing and exploiting this potential. This paper presents an analysis of National ICT policy of Bangladesh. Through the examination of ICT policy, in particular in the field of agriculture and rural development and analysis of applied policies and strategies implemented in these area, this paper identifies challenges and opportunities which provides lessons for policy-makers and practitioners involved in the field. This analysis reveals that the policy is inadequate to impact positively on the agriculture and rural development of Bangladesh. The policy places little emphasis on the integration and infusion of ICT in the countryʼs agriculture and rural development. Policy implications and suggestions are offered to ensure maximum use of ICT potentials in the countryʼs agriculture and rural development.
        4,300원
        380.
        2010.06 구독 인증기관 무료, 개인회원 유료
        This paper proposes using learning outcomes as means to measure knowledge transfer. It is based on a study to assess the effectiveness of knowledge transfer using the knowledge management concept of externalization by means of weblog access. In the knowledge era, knowledge transfer from the instructor to learners is important since the goal of educational system is the learners gaining the knowledge through the process of knowledge transfer from the instructor. To address the assumption, the study was conducted both quantitatively and qualitatively and collected data from the respondents. For quantitative analysis, the author surveyed measuring different variables targeting 326 undergraduate students randomly sampled, and the multiple choice test using 5- point Likert scale. The reliability analysis was analyzed. For qualitative analysis, the author collected data from 60 students’ weblog. Studies have shown that knowledge transfer can be problematic, and an effective transfer of knowledge can be difficult. The difficulty arises when the transferred knowledge becomes ambiguous, disrupted (hence incomplete), and distributed all over (making it difficult to link them together. Five hypotheses were formulated to examine the relationship between key characteristics of knowledge and learning outcome, in addition to content analysis on the externalized knowledge in the form of learners’ weblogs. The findings revealed some significant results involving the key characteristics of knowledge. The implication from this study can contribute much to the instructors and learners in knowing what knowledge that the instructor can transfer to learners and what knowledge is gained by learners as learning outcomes. In addition, the learning outcomes can tell the instructor to search for the right methodologies for improving the knowledge transfer to learners.
        5,700원