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  • 1
    ISSN: 1432-0606
    Keywords: Complexity ; Estimates by integrals ; Analytic centers ; Path-following method ; Interior-point method ; Linear programs ; 90C60 ; 90C05 ; 49M35 ; 68Q25
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper we study a particular class of primal-dual path-following methods which try to follow a trajectory of interior feasible solutions in primal-dual space toward an optimal solution to the primal and dual problem. The methods investigated are so-called first-order methods: each iteration consists of a “long” step along the tangent of the trajectory, followed by explicit recentering steps to get close to the trajectory again. It is shown that the complexity of these methods, which can be measured by the number of points close to the trajectory which have to be computed in order to achieve a desired gain in accuracy, is bounded by an integral along the trajectory. The integrand is a suitably weighted measure of the second derivative of the trajectory with respect to a distinguished path parameter, so the integral may be loosely called a curvature integral.
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  • 2
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention values ; Adsorption ; Glass capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Effect of adsorption on the retention values for some n-alkanes, n-alcohols and esters in glass capillary columns coated with PEG-20M was studied. Adsorption parameters for the used solutes were evaluated from the retention data.
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  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-exclusion ; Retention ; Adsorption effects ; Dicarboxylic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention values and distribution coefficients for C4−C9 dicarboxylic acids on a column packed with cation exchange resin in the H+ form were determined, using dilute HCl solution as eluent. Based on the Donnan membrane equilibrium and adsorption equilibrium, adsorption coefficients were evaluated, and the adsorption contributions to the retention of these analytes were estimated.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 29 (1990), S. 248-250 
    ISSN: 1612-1112
    Keywords: General chromatographic theory ; Exponentially modified Gaussian peaks ; Gamma peaks ; Peak formation mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that part of non-EMG peaks are gamma peaks. The describing function of a gamma peak is derived. The peak area equation and the formation mechanism of a gamma peak are discussed.
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  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Novel low energy molecular implantation of trimethyl phosphite was used to make rectifying junctions with indium contacts on boron doped diamond grown on silicon substrates. Diamond growth utilized hot-filament enhanced chemical vapor deposition (HFCVD). To our knowledge, this is the first report of molecular implantation on diamond and the only implanted junction with HFCVD polycrystalline diamond on silicon as the starting material. The rectifying contacts have high current density in forward bias and exhibit linear inverse squared capacitance-voltage characteristics at high frequencies, unlike other rectifying diamond junctions.
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  • 6
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
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  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Etching of hot-filament, chemical vapor deposited, diamond thin films utilizing low energy ion irradiation was investigated. The films used in this study were boron doped polycrystalline diamond, deposited on p-type (100) oriented silicon substrates. A low voltage dc corona discharge with an oxygen plasma was used to sputter etch the films. Surfaces were investigated by scanning electron microscopy and profilometry. Etch rates were approximately 500 A(ring)/min, depending on the various processing conditions. Characteristics of In/diamond/Si Schottky diodes were used to evaluate the electrical properties of diamond surfaces with various treatments. Results indicate that plasma etching can significantly affect Schottky device characteristics. © 1994 American Institute of Physics.
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  • 8
    ISSN: 1432-1432
    Keywords: phe operon ; tyr operon ; Attenuation ; Secondary structure ; Nucleotide sequence ; Erwinia herbicola ; Chorismate mutase ; Prephenate dehydatase ; Prephenate dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Extensive knowledge exists inEscherichia coli about the contiguouspheA andaroF-tyrA operons which have opposite transcription orientations and are separated by a bidirectional transcription terminator. The corresponding structural genes and individual components of the terminator and attenuator fromErwinia herbicola have been analyzed from an evolutionary vantage point. A 7.5-kb DNA fragment fromE. herbicola carrying the linkedpheA, tyrA, andaroF genes was cloned by functional complementation ofE. coli auxotrophic requirements. A 3,433-bp segment of DNA consisting of more than half ofaroF, all oftyrA, and the entire phenylalanine operon (promoter, leader region encoding the leader peptide and containing thephe attenuator, andpheA) was sequenced. A bidirectional transcription terminator was positioned between the divergently transcribedpheA andtyrA. The adjacentaroF andtyrA genes share a common transcription orientation, consistent with their probable coexistence within an operon. However,tyrA can be expressed efficiently from an internal promoter which appears to lie within the 3′ portion ofaroF. The gene order ispheA tyrA aroF inE. herbicola, with the same tail-to-tail arrangement of transcription known to exist inE. coli. ThepheL coding region of the phe operon was dominated by phenylalanine codons, seven of the 15 amino acid residues of the leader peptide beingl-phenylalanine. TheE. herbicola pheA andtyrA genes were 1,161 by and 1,119 by in length, respectively, and corresponded to deduced gene products having subunit molecular weights of 43,182 and 41,847. The deduced amino acid sequences ofPheA andTyrA were homologous at their N-termini, consistent with a common evolutionary origin of the chorismate mutase domains present at the amino terminus of bothPheA andTyrA. A detailed comparison of theE. coli andE. herbicola sequences was made. ThepheA, tyrA, andaroF genes ofE. herbicola exhibited high overall identity with the counterpartE. coli genes. Within the leader region of thephe operon, the leader peptide coding region was highly conserved. Although the 1:2 and 2′:3′ stems defining the pause structure and the antiterminator, respectively, were also highly conserved, RNA segment 4 of the attenuator terminator exhibited considerable divergence, as did the distal portion of the attenuator region. Within the span of attenuator region encoding the three stern-loop structures of mRNA secondary configuration, hot spots of base-residue divergence were localized to looped-out regions. No changes occurred which would simultaneously disrupt alternative pairing relationships of secondary configuration. The bidirectional terminator betweenpheA andtyrA has diverged very substantially. Much of the promoter region and the untranslated region between the promoter and thepheL coding region also differed considerably between the two organisms.
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  • 9
    ISSN: 1573-4846
    Keywords: metal particles ; surface plasma resonance ; coating films ; composites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Control of the optical properties of gel-derived oxide films containing fine metal particles is described. The duration of the aging of Si(OC2H5)4-derived sols and the amount of water for hydrolyzing Si(OC2H5)4 were found to greatly affect the size and the shape of Au particles formed in the silica matrix, and accordingly the optical absorption of the Au/SiO2 composite films. Employing dielectric media with high refractive indices like TiO2 was shown to shift the absorption peak of Au particles to longer wavelengths. Pd/TiO2 and Pt/TiO2 composite films showed absorption in the visible region.
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  • 10
    ISSN: 0003-276X
    Keywords: Rat male accessory sex glands ; Coagulating gland ; Transglutaminase ; Stecretion ; Stroma ; Hormonal regulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effects of androgen deprivation and estrogen stimulation on rat coagulating gland were determined by immunohistochemistry and morphometric quantification of different tissue compartments. In castrated or estrogen-treated or estrogen-treated castrated animals, the reduction of the glandular lumen is the most obvious morphological alteration, which is accompanied by an increase in stromal tissue, especially within the lamina propria. Regressive changes occur most rapidly in castrated animals (already by the end of the first week), slower in estrogen-treated castrated animals, and still slower in estrogen-treated normal animals. In castrated animals, epithelium shows a reduction of rough endoplasmic reticulum, loss of secretory blebs, and a decrease of cell size and immunoreactivity for secretory transglutaminase. The reduction of glandular lumen results from an impressive increase in connective tissue of the lamina propria. Smooth muscle cells become atrophic in castrated animals, less so in estrogen-treated animals and in castrated estrogen-treated animals. A relative increase in thickness of the smooth muscle cell layer occurs in all experimental groups and is most obvious in estrogen-treated normal animals. The proportion of myofilament and intermediate filament proteins (smooth muscle-specific actin and desmin immunoreactivities) remains nearly unaltered in these cells after hormonal challenge. A redistribution of intermediate filaments occurs forming thicker bundles within the cells. No indication for increased mitotic activity of estrogenized smooth muscle cells has been found. After castration, and after estrogen treatment, the fibroblasts and the smooth muscle cells, respectively, appear responsible for the architectural changes within the coagulating gland. Reactions of the stroma are differentially regulated after estrogen treatment and androgen deprivation. No indication for increased biosynthetic activities of smooth muscle cells has been observed in any of the experimental conditions. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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