1,721,024 research outputs found
Novel oscillator incorporating a compact tunable resonant cell with high efficiency and superior harmonic characteristics
No full textThis paper presents a novel microwave oscillator incorporating a simple microstrip ring-type resonant cell as its terminating resonance component. Reduced chip size, higher DC-AC power efficiency, and superior harmonic characteristics can be achieved from the introduction of this type of compact microstrip ring resonator cell. The oscillator provides a second harmonic suppression of 26.51 dB and all output power of 2.046 dBm, with 28% efficiency, at ail oscillation frequency of 2.11 GHz. (c) 2006 Wiley Periodicals, Inc
Synthesis and thermal properties of poly(Schiff bases) containing dicyanovinyl group and their copolymers
No full textPoly(Schiff bases) and their copolymers incorporating dicyanovinyl group in the main chain were prepared by the solution polymerization of a dicyanovinyl-containing monomer, p-bis[1-(4-formylphenoxy)-2,2-dicyanovinyl]benzene ((4) under bar), and terephthalaldehyde (TA) with 4-aminophenyl ether (ODA). The resulting polymers possess intrinsic viscosities 0.42 similar to 0.20 dL/g in the case of polymers <(P(1/0))under bar>similar to<(P(2/1))under bar>. The homopolymer derived from (4) under bar and ODA is easily soluble in polar aprotic solvents. However, the solubility of the polymers in NMP decreased apparently with the increase of the content of TA in the polymer chain. Attempts to prepare high-molecular weight polymers from higher content of TA were unsuccessful probably due to the precipitation of polymer during polymerization. The polymers show a large exotherm in differential scanning calorimetry and undergo a curing reaction around 350 degrees C to form insoluble material in solvent. Almost all the poly(Schiff bases) exhibited 10% weight loss between 480 similar to 540 degrees C and 88 similar to 5% residual weight at 500 degrees C in a nitrogen atmosphere
Hydrogen storage characteristics of metal oxide doped Al-MCM-41 mesoporous materials
No full textThe feasibility and perspectives of Al-MCM-41 as hydrogen storage systems were evaluated. The Al-MCM-41 with varying content of aluminum was synthesized by hydrothermal process. Different metal oxides were impregnated over Al-MCM-41 by incipient wetness impregnation (IWI) method. The crystallnity of the samples were interrogated by powder X-ray diffraction. The textural properties were measured by N-2 sorption method. The structural properties were established by Transmission Electron Microscope (TEM). The gas chromatogram indicates that hydrogen uptake in Al-MCM-41 is strongly dependent on density of Bronsted acid sites and the amount of metal oxide (especially NiO). (c) 2007 Elsevier B.V. All rights reserved.Financial support from the Center for Advanced Materials
Processing (CAMP) of the 21st Century Frontier
R&D Program funded by the Korean Ministry of Science
and Technology and Brain Korea 21 Program from Korean
Ministry of Education are gratefully acknowledged
Genetic variability in east Asian dogs using microsatellite loci analysis
No full textAn analysis of eight microsatellite loci in 213 animals was performed to define the genetic structure and variability of 11 East Asian native dog populations. Allele diversity, observed heterozygosities, expected heterozygosities, F-statistics, G(ST) estimates, number of migrants per generation (Nm), and Nei's DA distance were calculated. Expected mean heterozygosities of Asian native dogs varied within a range of 0.310-0.718 with a mean value of 0.580. In a sample of 11 Asian dogs, the highest genetic diversity was exhibited in the Korean native dogs and the lowest in the Shiba, the Japanese native dog. All populations except the Kishu and Akita showed statistically significant deviation from Hardy-Weinberg equilibrium at more than one locus. After corrections for multiple significance tests, deviations over all loci were statistically significant in 7 of 11 dog populations, meaning that Asian dogs are genetically subdivided (global F-ST = 0.154). Despite the locus-specific deviations, statistically significant departures from the Hardy-Weinberg equilibrium reflect deviations In the direction of heterozygote deficit, the global F-IS being 0.072. In the neighbor-joining and unweighted pair group method with arithmetic mean (UPGMA) dendrograms based on Nei's DA distance, the Korean native breeds (the Sapsaree and the Jindo) were grouped together, then with the Eskimo dog. The two Japanese native dogs (the Hokkaido and the Akita) also clustered together, with moderate bootstrap support. In spite of some deviation, the three-dimensional scattergram based an principal components supported the conclusions suggested by the dendrograms based on Nei's DA distance. From these two analyses, the Korean native dogs formed the closest groups and then showed a close relationship to the Eskimo dogs, reflecting the fact that the Korean native dogs might be originated from dogs in the northern part of Far East Asia
Suitability of AFLP markers for the study of Genetic relationships among Korean native dogs
No full textTo determine the genetic relationships among domestic dog breeds, we performed both a sequence comparison of mitochondrial DNA (mtDNA) and an amplified fragment length polymorphisms (AFLP) analysis. Three of four regions of mtDNA, cytochrome b, cytochrome oxidase subunit II, and 16S rRNA genes were highly homogeneous among dog breeds, whereas the other region, the control region, showed relatively high polymorphisms with a maximum percentage difference of 3.18%. However, the control region showed extensive polymorphism even within breeds, and the relationship tree derived from the data could not clearly delimit distinct breeds. 19 EcoRI/MseI primer combinations were used to generate AFLP markers among 25 dogs from 11 breeds including three Korean native dogs. These amplification reactions allowed the detection of more than 1900 amplification products of which 408 were identified as polymorphic bands. Unrooted neighbor-joining tree based on dissimilarity values showed that the Korean native dogs were clustered together with the Asian dogs and that the Asian originated dogs were clustered separately from Western originated dogs. A consensus tree using parsimony method also showed Korean native dogs were grouped separately from the other dogs with moderate bootstrap values. Taken together, it is concluded that AFLP analysis is a more informative tool for revealing genetic relationships among dog breeds than mtDNA sequence comparison
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Genomic analysis and functional expression of canine dopamine D2 receptor
No full textDopamine D2 receptor (DRD2) is one of the five dopamine receptors with seven transmembrane domains that are coupled to the G protein. We have cloned and characterized the genomic and cDNA sequences of the canine DRD2 gene, which are 12.7 and 2.7 kb in size, respectively. The genomic DNA is composed of seven exons and six introns, encoding a 443 amino acid protein with 95% amino acid identity to other mammalian D2 receptors. A length polymorphism was detected in intron 3 of the receptor gene. We also characterized alternatively spliced forms of DRD2 cDNAs, DRD2L and DRD2S. They showed a higher level of expression in midbrain and thalamus. The ratio between the long and short form is similar in RT-PCR reaction. In human and rodent, the same two spliced forms are known to be coupled to G(i)-type heterotrimeric GTP binding protein, thereby opening an inwardly rectifying potassium channel, GIRK1. When the canine DRD2L and DRD2S were heterologously expressed in Xenopus oocytes, both forms activated GIRK1 potassium channels through coupling with Gi protein. This activation was dose-dependent, demonstrating its ligand specificity. (C) 2000 Elsevier Science B.V. All rights reserved
- …
