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  • Articles  (33)
  • Springer  (19)
  • Elsevier  (13)
  • Wiley-Blackwell  (1)
  • AGU (American Geophysical Union)
  • Oxford University Press
  • 2015-2019
  • 2010-2014
  • 1990-1994  (33)
  • 1960-1964
  • 1993  (33)
  • Biology  (20)
  • Physics  (14)
  • Electrical Engineering, Measurement and Control Technology  (2)
  • Political Science
  • Architecture, Civil Engineering, Surveying
Collection
  • Articles  (33)
Years
  • 2015-2019
  • 2010-2014
  • 1990-1994  (33)
  • 1960-1964
Year
Journal
  • 1
    ISSN: 1824-3096
    Keywords: Ethanol consumption Harris lines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Harris lines represent episodes of growth arrest followed by recovery, thus reflecting episodes of mismatched imbalance between energy intake and energy expenditure. Consumption of ethanol during the growth period — formerly extended in our wine-producing rural areas- may lead to such a situation, due at least in part to the energy-wasteful MEOS-linked ethanol metabolism. Based on these facts, in the present study we have analysed the relationship between ethanol intake during growth period and the presence of Harris lines in the right tibia in 100 consecutive adult patients admitted to our hospitalization unit. Early ethanol consumption was strongly related with the presence of two or more, and three or more Harris lines, so that ethanol consumption should be considered in the differential diagnosis of Harris lines, and conversely, the presence of Harris lines point to ethanol consumption during growth period. This association was independent from coexisting starvation and/or illness.
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  • 2
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Based on experimental work on the ontogeny of the electroretinogram circadian rhythm in crayfish, we present a mathematical model simulating changes in both frequency and amplitude of the electroretinogram oscillation during several developmental stages until shortly before the adult age. Simultaneously, we propose a hypothetical oscillation in the hormonal release whose frequency is imposed on the electroretinogram oscillation. The model consists of two coupled nonlinear oscillators in which a dynamical response is obtained mainly through an Andronov-Hopf bifurcation. Through the construction of the model, a biological hypothesis about the essential elements underlying the ERG circadian rhythm and their interrelations is formulated and discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 55 (1993), S. 561-583 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A general model of zymogen activation is proposed and explicit kinetic equations for the time courses of the various species and products involved are given. These equations are valid for the whole course of the reaction and therefore for both the transient phase and the steady state. This model is sufficiently general to include mechanisms possessing one or more steps of zymogen activation besides possible steps of inhibition (reversible or irreversible) or inactivation.
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  • 4
    ISSN: 1432-0649
    Keywords: 42.60.By ; 32.30.Rj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report lasing for the first time in nickel on the neon-like J=0→1, 3p→3s transition at 231 Å as well as several weaker transitions including the J=2»1 lines at 298 Å and 304 Å. Amplification is seen only when the prepulse technique of using a low intensity prepulse before the main optical drive pulse is used to illuminate the nickel target. The prepulse technique is also shown to produce lasing in copper and dramatically improve the output of the germanium laser.
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  • 5
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In Catharanthus roseus cell cultures the time courses of four enzyme activities, tryptophan decarboxylase (TDC), strictosidine synthase (SSS), geraniol-10-hydroxylase (G10H) and anthranilate synthase (AS), and alkaloid accumulation were compared under two different culture conditions (low-inoculum density and high-inoculum density on induction medium) and a control on growth medium. In growth medium a transient increase in TDC activity was first observed after which G10H reached its maximum activity; only tryptamine accumulated, no ajmalicine could be detected. Apparently, a concerted induction of enzyme activities is required for ajmalicine formation. Cells inoculated in induction medium showed such a concerted induction of AS, TDC and G10H activities. After 30 days the low-density culture had accumulated six times more ajmalicine (in μmoles/g) than the high-density culture. Thus, increase in biomass concentration (high-density cultures) did not enhance the total alkaloid production. The major differences observed in enzyme levels between high-and low-density cultures were in the AS and TDC activities, which were two to three times higher in the low-density culture, indicating that there is a positive correlation between ajmalicine formation and AS and TDC activities.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 144 (1993), S. 399-402 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The distribution of significant solar activity for the northern and southern solar hemispheres from 1964 through 1979 is studied. Two 90-degree wide active longitudes, separated 180 degrees and rotating with a velocity 1% faster than the solar surface, are proposed.
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  • 7
    ISSN: 1432-1939
    Keywords: Fire intensity ; Adenostoma fasciculatum ; Lignotuber ; Resprouting ; Herbivory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the population structure of the lignotuberous resprouter Adenostoma fasciculatum were investigated by experimentally burning at various intensities an old stand in southern California chaparral. Survival after fire, time of resprouting, herbivory, and survival after resprouting were monitored for more than 1 year after the fire. Greater fire intensity increased plant mortality and the size of plants that died as a consequence of the fire. Time from the fire until resprouting increased with increasing fire intensity and was related to plant size: the larger the plants the earlier they resprouted. Post-resprouting mortality also increased with fire intensity and was related to time of resprouting. Herbivory increased with fire intensity and the size of plants affected by it changed with the intensity of the fire. Fire intensity had profound direct and indirect effects on the population structure of Adenostoma fasciculatum. Plant size strongly determined the direct and indirect lethal effects of fire.
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  • 8
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of terpenoid precursor feeding and elicitation by a biotic elicitor on alkaloid production of Catharanthus roseus suspension cultures were studied. After addition of secologanin, loganin or loganic acid an increase in the accumulation of ajmalicine and strictosidine and a decrease of tryptamine level was observed in non-elicited cells. Elicitation increased tryptamine accumulation in non-fed cells but it did not further increase alkaloid accumulation in precursor-fed cells. A decrease of tryptamine level was also observed, despite the induction of the tryptamine pathway after elicitation. Feeding mevalonic acid did not increase alkaloid accumulation in any studied case.
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  • 9
    ISSN: 1573-5028
    Keywords: Anabaena sp. ; CpcD-like domain ; ferredoxin-NADP+ reductase ; petH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The complete nucleotide sequence of the petH gene encoding ferredoxin-NADP+ reductase from the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7119 has been determined. The encoded polypeptide is 136 amino acids longer than the enzyme obtained after purification to homogeneity. The extended N-terminal domain consists of 80 amino acids which shows homology to the CpcD phycobilisome linker polypeptide, through which FNR might be anchored to the thylakoid-bound phycobilisomes. A 56 amino acid interdomain fragment is found which could be a target for proteolysis.
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  • 10
    ISSN: 1617-4623
    Keywords: Nitrogen fixation ; Novel type of NifU ; Ethane formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA sequence analysis of a 3494-bp HindIII-Bc1I fragment of the Rhodobacter capsulatus nif region A revealed genes that are homologous to ORF6, nifU, nifS, nifV and nifW from Azotobacter vinelandii and Klebsiella pneumoniae. R. capsulatus nifU, which is present in two copies, encodes a novel type of NifU protein. The deduced amino acid sequences of NifUI and NifUII share homology only with the C-terminal domain of NifU from A. vinelandii and K. pneurnoniae. In contrast to nifA andnifB which are almost perfectly duplicated, the predicted amino acid sequences of the two NifU proteins showed only 39% sequence identity. Expression of the ORF6-nifU ISVW operon, which is preceded by a putative σ54-dependent promoter, required the function of NifA and the nif-specific rpoN gene product encoded by nifR4. Analysis of defined insertion and deletion mutants demonstrated that only nifS was absolutely essential for nitrogen fixation in R. capsulatus. Strains carrying mutations in nifV were capable of very slow diazotrophic growth, whereas ORF6, nifU I and nifW mutants as well as a nifU I/nifUII, double mutant exhibited a Nif+ phenotype. Interestingly, R. capsulatus nifV mutants were able to reduce acetylene not only to ethylene but also to ethane under conditions preventing the expression of the alternative nitrogenase system. Homocitrate added to the growth medium repressed ethane formation and cured the NifV phenotype in R. capsulatus. Higher concentrations of homocitrate were necessary to complement the NifV phenotype of a polar nifV mutant (NifV−NifW−), indicating a possible role of NifW either in homocitrate transport or in the incorporation of this compound into the iron-molybdenum cofactor of nitrogenase.
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