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  • 1
    Electronic Resource
    Electronic Resource
    Characterizing and recognizing the visibility graph of a funnel-shaped polygon (1995)
    Springer
    Algorithmica 14 (1995), S. 27-51 
    Details
    ISSN: 1432-0541
    Keywords: Computational geometry ; Funnel-shaped polygon ; Visibility graph ; Characterizing and recognizing visibility graphs ; Weakly triangulated graph ; Perfect graph
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A funnel, which is notable for its fundamental role in visibility algorithms, is defined as a polygon that has exactly three convex vertices, two of which are connected by a boundary edge. In this paper we investigate the visibility graph of a funnel which we call an F-graph. We first present two characterizations of an F-graph, one of whose sufficiency proof itself is a linear time Real RAM algorithm for drawing a funnel on the plane that corresponds to an F-graph. We next give a linear-time algorithm for recognizing an F-graph. When the algorithm recognizes an F-graph, it also reports one of the Hamiltonian cycles defining the boundary of its corresponding funnel. This recognition algorithm takes linear time even on a RAM. We finally show that an F-graph is weakly triangulated and therefore perfect, which agrees with the fact that perfect graphs are related to geometric structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01300372
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  • 2
    Electronic Resource
    Electronic Resource
    The Sol-Gel Chemistry of Ferroelectric SrBi2Ta2O9 Thin Layers (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 301-304 
    Details
    ISSN: 1573-4846
    Keywords: precursor chemistry ; SBT thin film ; single precursor ; single crystal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A characterization of sol-gel precursors of SrBi2Ta2O9 (SBT) has been carried out. Each molecular precursor, [SrBi2+x Ta2(OCH2CH2OCH3)18] n (1) (x = 0.0, 0.2, and 0.4) and [SrTa2(OEt)(O i Pr)11( i PrOH)2] (2) was prepared from the mixtures of Bi(OR)3, Sr(OR)2, and Ta(OR)5 (R = Et, i Pr, and CH2CH2OCH3), respectively. 1H and 13C NMR spectroscopy and powder X-ray diffractometry have been used to characterize precursor molecules and their oxides, respectively. Especially, X-ray single crystal studies of complex 2 show that the molecule is made up of three octahedra; the central [SrO6] octahedron is sharing two neighboring edges with the peripheral [TaO6] ones. The SBT film derived from the precursor 1 presents outstanding ferroelectric properties (P r = 9 μC/cm2; E c = 0.8 V).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008725430345
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  • 3
    Electronic Resource
    Electronic Resource
    Efficient Algorithms for Computing a Complete Visibility Region in Three-Dimensional Space (1998)
    Springer
    Algorithmica 20 (1998), S. 201-225 
    Details
    ISSN: 1432-0541
    Keywords: Key words. Computational geometry, Complete visibility, Penumbra.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Given a set P of polygons in three-dimensional space, two points p and q are said to be visible from each other with respect to P if the line segment joining them does not intersect any polygon in P . A point p is said to be completely visible from an area source S if p is visible from every point in S . The completely visible region CV(S, P) from S with respect to P is defined as the set of all points in three-dimensional space that are completely visible from S . We present two algorithms for computing CV(S, P) for P with a total of n vertices and a convex polygonal source S with m vertices. Our first result is a divide-and-conquer algorithm which runs in O(m 2 n 2 α(mn)) time and space, where α(mn) is the inverse of Ackermann's function. We next give an incremental algorithm for computing CV(S,P) in O(m 2 n+mn 2 α(n)) time and O(mn+n 2 ) space. We also prove that CV(S,P) consists of Θ(mn+n 2 ) surface elements such as vertices, edges, and faces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009193
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  • 4
    Electronic Resource
    Electronic Resource
    Linear-Time Algorithms for Finding the Shadow Volumes from a Convex Area Light Source (1998)
    Springer
    Algorithmica 20 (1998), S. 227-241 
    Details
    ISSN: 1432-0541
    Keywords: Key words. Computational geometry, Penumbra, Umbra, Computer graphics.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. An area light source in three-dimensional space shines past a scene polygon to generate two types of shadow volumes for each scene polygon, i.e., one with partial occlusion and the other with complete occlusion. These are called penumbra and umbra, respectively. In this paper we propose linear-time algorithms for computing the penumbra and the umbra of a scene polygon from an area light source, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009194
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  • 5
    Electronic Resource
    Electronic Resource
    Oxidative dehydrogenation of 4-vinylcyclohexene into styrene over ZrO2 catalyst promoted with Fe2O3 and CaO (2000)
    Springer
    Catalysis letters 69 (2000), S. 93-101 
    Details
    ISSN: 1572-879X
    Keywords: oxidative dehydrogenation ; deactivation ; VCH ; styrene ; ZrO2 ; Fe2O3 ; CaO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidative dehydrogenation of 4-vinylcyclohexene (VCH) into styrene was carried out in the presence of oxygen over a ZrO2 catalyst promoted with Fe2O3 and CaO. Intrinsically, ZrO2 showed high dehydrogenation activity, which resulted in 80% styrene selectivity with 45% conversion at 425 °C and LHSV 3 h−1. When the ZrO2 was further promoted with calcium and iron, CaO/Fe2O3/ZrO2, the highest styrene selectivity of 88.9% was obtained as well as the lowest deactivation. The deactivation of catalyst was prohibited properly through the introduction of oxygen in the reactant together with the modification of Fe2O3/ZrO2 with CaO. The CaO/Fe2O3/ZrO2 showed constant catalytic activity and selectivity for more than 50 h without deactivation. The selectivity of styrene was strongly influenced by the mole ratio of O2/VCH and 95% selectivity with 80% conversion was obtained at O2/VCH mole ratio of 6 over Fe2O3/ZrO2. It is thought that the oxidative dehydrogenation proceeds through the dehydrogenation (DH) of ring-hydrocarbon of VCH followed by selective combustion of hydrogen (SHC) and the high selectivity of styrene was achieved by the bi-functional role of ZrO2 for DH and SHC reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019049301945
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  • 6
    Electronic Resource
    Electronic Resource
    The Impact of Competition on the Efficiency of Public Enterprise: The Case of Korea Telecom (2000)
    Springer
    Asia Pacific journal of management 17 (2000), S. 423-442 
    Details
    ISSN: 1572-9958
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract The notion of total productivity can be employed in evaluating the performance of monopolistic public enterprises in a transitional period. This study comparatively analyzes the efficiency change of Korea Telecom (KT) once the biggest telecommunications service provider in Korea but now facing both domestic and foreign competition. Dichotomizing the reference period into before-competition and after-competition and using Data Envelopment Analysis (DEA), we measure the technical efficiency, the allocative efficiency and the overall efficiency and highlight the differences between two periods. It is observed that the overall efficiency has been significantly improved mainly due to the enhancement of the allocative efficiency but the technical efficiency has been slightly improved. The major cause of insignificant improvement of technical efficiency is due to hothouse competition and excessive regulation on management of KT. Monopolistic firms in transition can respond to the external competition by reducing input cost and excessive capital. There may exist a considerable time lag, however, in achieving the improvement of technical efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015886331408
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  • 7
    Electronic Resource
    Electronic Resource
    A Facile Method of Synthesis of a Calix[4]arene Amide and the Crystal Structure of a Self-assembled Calix[4]arene Amide via van Der Waals Interaction (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 36 (2000), S. 473-478 
    Details
    ISSN: 1573-1111
    Keywords: calix[4] arene amide ; self-assembly ; X-ray crystal structure ; aminolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new facile method of synthesis of calix[4]arene amide via the aminolysis of the calix[4]arene esters was reported. One ethyl ester of the compound (2) was aminolysized byn-butylamine. The crystal structure of compound (1)shows that one ethyl ester of compound (1) enters into thecavity of another compound (1) forming a long chainhost-guest supramolecule. From the 2D NMR data, the compound(1) does not assemble in THF or CHCl3 solution. The CH-π interaction and crystallization energy might be theimportant driving forces for forming the self-assembledcalix[4]arene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008161320091
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  • 8
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of aquabis(2,2′-bipyridine)nitratomanganese(II) nitrate monohydrate (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 605-607 
    Details
    ISSN: 1572-8854
    Keywords: Manganese(II) nitrate ; 2,2′-bipyridine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new monomeric manganese(II) nitrate complex with 2,2′-bipyridine (bpy), [Mn(bpy)2(NO3)(H2O)](NO3)·H2O, has been prepared and characterized by X-ray crystallography. The complex crystallizes in the triclinic space group $$P\bar 1$$ witha=9.721(3),b=14.691(5),c=8.578(3) Å, α=106.79(3), β=96.05(3), γ=82.55(3)°,V=1159.9 Å3 andZ=2. The structure comprises discrete cation [Mn(bpy)2(NO3)(H2O)]+ in which the metal atom is coordinated by a pair of bidentate bpy ligands [Mn−N=2.261(4)−2.299(4) Å], a unidentate nitrato [Mn−O=2.284(4) Å] and aqua [Mn−O=2.160(3) Å] ligands in a highly distorted octahedral arrangement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01667032
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  • 9
    Electronic Resource
    Electronic Resource
    Suprageneric classification of peptidoglycan group B actinomycetes by nucleotide sequencing of 5S ribosomal RNA (1993)
    Springer
    Antonie van Leeuwenhoek 64 (1993), S. 307-313 
    Details
    ISSN: 1572-9699
    Keywords: Agromyces ; Aureobacterium ; Clavibacter ; Curtobacterium ; Microbacterium ; 5S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 5S ribosomal RNA sequences were determined for thirteen actinomycetes mainly representatives with the rare group B type peptidoglycan. The primary and secondary structure of the resultant sequences were of the type characteristic of Gram-positive bacteria with DNA rich in guanine plus cytosine. The sequencing and associated chemotaxonomic data provide compelling grounds for classifying actinomycetes with a group B type peptidoglycan in a single family. The familyMicrobacteriaceae fam. nov. is proposed to accommodate actinomycetes classified in the generaAgromyces, Aureobacterium, Clavibacter, Curtobacterium andMicrobacterium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00873089
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  • 10
    Electronic Resource
    Electronic Resource
    A new class II rice chitinase, Rcht2, whose induction by fungal elicitor is abolished by protein phosphatase 1 and 2A inhibitor (1998)
    Springer
    Plant molecular biology 37 (1998), S. 523-534 
    Details
    ISSN: 1573-5028
    Keywords: class II chitinase ; dephosphorylation ; defense response ; elicitors ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Among the four classes of chitinase, a class II chitinase had not yet been reported for rice. We have isolated and characterized a class II acidic chitinase, Rcht2, from rice (Oryza sativa L. cv. Cheongcheongbyeo). The protein consists of a single polypeptide chain of 261 amino acid residues and includes a putative signal sequence of 29 amino acids at its N-terminus. It has a calculated molecular mass of 27 642 Da and an isoelectric point of 5.56. The Rcht2 chitinase lacks the cysteine-rich and hinge domains in the N-terminal region of the protein, which is the criterion for its classification as a class II chitinase. Comparison of the genomic and the cDNA sequence revealed that the coding region of Rcht2 consist of three exons of 301, 112, and 370 bp separated by two introns of 89 and 984 bp. In suspension-cultured rice cells, the transcript level of Rcht2 was dramatically increased by treatment with both glycol chitin and fungal elicitor. The application of protein phosphatase 1 and 2A inhibitors, calyculin A and okadaic acid, effectively abolished the induction of Rcht2 in response to fungal elicitor. In contrast, the activation of Rcht2 transcript was not inhibited by both cycloheximide and protein kinase inhibitors. These results demonstrate that protein dephosphorylation events play a crucial role in the elicitor-mediated induction of Rcht2 in rice cells, while de novo protein synthesis is not required for induction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005960313459
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