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  • Cyanobacteria  (5)
  • Fast Fourier transform  (4)
  • Springer  (9)
  • American Association of Petroleum Geologists (AAPG)
  • Elsevier
  • 1980-1984  (9)
  • 1984  (9)
Collection
Keywords
Publisher
  • Springer  (9)
  • American Association of Petroleum Geologists (AAPG)
  • Elsevier
Years
  • 1980-1984  (9)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Morphology and ultrastructure of the cyanobacterium Mastigocladus laminosus growing under nitrogen-fixing conditions (1984)
    Springer
    Archives of microbiology 137 (1984), S. 97-103 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Heterocysts ; Utrastructure ; Cytology ; Akinetes ; Mastigocladus laminosus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphological and ultrastructural characteristics of the cyanobacterium Mastigocladus laminosus growing under N2-fixing conditions were examined with light and electron microscopy. Vegetative cells in narrow filaments contained randomly arranged segments of thylakoid membrane, centrally located carboxysomes (polyhedral bodies), peripherally located lipid bodies, and large numbers of polysaccharide granules in addition to nuclear material and ribosomes. The ultrastructural characteristics of cells in wide filaments were similar, except for increased numbers of carboxysomes and lipid bodies. Heterocytes and proheterocysts developed at a variety of locations in narrow filaments, wide filaments, and the lateral branches off of wide filaments. Akinetes were not observed in any of the filaments. The morphological characteristics of heterocysts and proheterocysts were variable and depended on those of the vegative cells from which the heterocysts and proheterocysts developed. Mature M. laminosus heterocysts were somewhat similar to those formed in other cyanobacterial genera, but they possessed a number of distinct and unique ultrastructural characteristics, including (i) the absence of a fibrous and, possibly, a laminated wall layer, (ii) the presence many closely packed membranes throughout most of the cytoplasm, and (iii) the presence of unidentified, spherical inclusion bodies of variable electron density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414447
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  • 2
    Electronic Resource
    Electronic Resource
    Evidence for an ammonium transport system in free-living and symbiotic cyanobacteria (1984)
    Springer
    Archives of microbiology 137 (1984), S. 241-246 
    Details
    ISSN: 1432-072X
    Keywords: Ammonium transport ; Anabaena azollae ; Anabaena variabilis ; Cyanobacteria ; Methylammonium transport ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The free-living cyanobacterium Anabaena variabilis showed a biphasic pattern of 14CH3NH 3 + uptake. Initial accumulation (up to 60 s) was independent of CH3NH 3 + metabolism, but long-term uptake was dependent on its metabolism via glutamine synthetase (GS). The CH3NH 3 + was converted into methylglutamine which was not further metabolised. The addition of l-methionine-dl-sulphoximine (MSX), to inhibit GS, inhibited CH3NH 3 + metabolism, but did not affect the CH3NH 3 + transport system. NH 4 + , when added after the addition of 14CH3NH 3 + , caused the efflux of free CH3NH 3 + ; when added before 14CH3NH 3 + , NH 4 + inhibited its uptake indicating that both NH 4 + and CH3NH 3 + share a common transport system. Carbonylcyanide m-chlorophenylhydrazone and triphenyl-methylphosphonium both inhibited CH3NH 3 + accumulation indicating that the transport system was Δψ-dependent. At pH 7 and at an external CH3NH 3 + concentration of 30 μmol dm-3, A. variabilis showed a 40-fold intracellular accumulation of CH3NH 3 + (internal concentration 1.4 mmol dm-3). Packets of the symbiotic cyanobacterium Anabaena azollae, directly isolated from the water fern Azolla caroliniana, also showed a Δψ-dependent NH 4 + transport system suggesting that the reduced inhibitory effect of NH 4 + on nitrogenase cannot be attributed to the absence of an NH 4 + transport system but is probably related to the reduced GS activity of the cyanobiont.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414551
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  • 3
    Electronic Resource
    Electronic Resource
    Osmotic adjustment in cyanobacteria from hypersaline environments (1984)
    Springer
    Archives of microbiology 138 (1984), S. 333-337 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Osmotic adjustment ; Osmoregulation ; Quaternary ammonium compounds ; Glycine betaine ; Halotolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intracellular concentrations of the monovalent inorganic cations K+ and Na+, low molecular weight carbohydrates and quaternary ammonium compounds have been determined for 4 strains of cyanobacteria (Aphanothece halophytica, Coccochloris elabens, Dactylococcopsis salina and Synechocystis DUN52) originally isolated from hypersaline habitats (i.e. habitats with a salinity greater than that of seawater) over a range of external salt concentration (from 50% to 400% seawater). Intracellular cation levels (Na+ and K+) were determined to be within the range 80–320 mmol · dm-3 (cell volume), showing only minor changes in response to salinity. Intracellular carbohydrates were found to comprise a negligible component of the intracellular osmotic potential [at 2–19 mmol · dm-3 (cell volume)], throughout the salinity range. Quaternary ammonium compounds, however, were recorded in osmotically significant quantities [up to 1,640 mmol · dm-3 (cell volume)] in these strains, showing major variation in response to salinity. Thus Synechocystis DUN 52 showed an increase in quaternary ammonium compounds in the oder of 1,200 mmol · dm-3 between 50% and 400% seawater medium, accounting for a significant proportion of the change in external osmotic potential. Examination of intact cells and cell extracts using 13C and 1H nuclear magnetic resonance (NMR) spectroscopy confirmed the presence of the quaternary ammonium compound glycine betaine as the major osmoticum in the 4 strains; no other compounds were detected during NMR assays. These results suggest a common mechanism of osmotic adjustment, involving quaternary ammonium compounds, in cyanobacteria from hypersaline environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410900
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  • 4
    Electronic Resource
    Electronic Resource
    Surface charge on thylakoid membranes: regulation of photosynthetic electron transfer in cyanobacteria (1984)
    Springer
    Archives of microbiology 138 (1984), S. 54-57 
    Details
    ISSN: 1432-072X
    Keywords: O2 evolution ; Lag-phase ; Membrane surface charge ; Transmembrane H+ electrochemical potential difference ; 9-Aminoacridine fluorescence changes ; Ionophore antibiotics ; Cyanobacteria ; Anabaena variabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The establishment of the steady-state rate of photosynthetic O2 evolution by cells of Anabaena variabilis and other cyanobacteria was found to be preceded by a lag-phase the duration of which depended on the time of cell preincubation in the dark. Electron acceptors (benzoquinone, N,N,N′,N′-tetramethyl-p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine or 2,6-dichlorophenolindophenol) abolished the lag-phase as well as the inhibitory effect of cyanide on electron transfer. Mono-, di-and trivalent cations added to the cell suspension markedly reduced the lag-phase. As cation concentrations were increased, acceleration and subsequent deceleration of the O2 evolution rate were observed. The efficient concentrations of cations decreased as their valency increased. The lag-phase and the rate of photosynthetic O2 evolution by the blue-green algae are suggested to depend on the value of the membrane surface charge governing the electrostatic interaction between unidentified membrane-bound redox components. The combination of valinomycin and nigericin as well as gramicidin D enhanced the duration of the lagphase by deenergization of thylakoid membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425407
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  • 5
    Electronic Resource
    Electronic Resource
    Cell division in baeocyte producing cyanobacteria (1984)
    Springer
    Protoplasma 123 (1984), S. 104-115 
    Details
    ISSN: 1615-6102
    Keywords: Constrictive binary fission ; Cyanobacteria ; Development ; Multiple fission ; Septate binary fission ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An ultrastructural examination of cell division in two baeocyte producing cyanobacteria,Pleurocapsa minor andDermocarpa violaceae, reveals two distinct patterns of binary (transverse) fission. Septate binary fission, inPleurocapsa minor, involves centripetal synthesis and deposition of the mucopolymer cell wall layer (L 2). The ingrowth of the cytoplasmic membrane and L 1 cell wall layer, along with the synthesis of the L 2 cell wall layer, results in the formation of a prominent septum. Partitioning of the cell occurs by the constriction of the outer cell wall layers (L 3 and L 4) through the septum. InDermocarpa violaceae, constrictive binary fission occurs by the simultaneous ingrowth or constriction of the cytoplasmic membrane and all cell wall layers (L1, L2, L3, L4). Septate and constrictive binary fission may proceed symmetrically (medially) or asymmetrically (nonmedially). Multiple fission occurs regularly inDermocarpa violaceae and provides for a rapid means of reproduction when compared to binary fission. Successive radial and tangential divisions of the protoplast result in formation of many small daughter cells (baeocytes). The process of multiple fission is similar to septate binary fission with reduced septa being formed. However, constriction of the outer cell wall layers, through the septa, proceeds concurrently with septum formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283581
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  • 6
    Electronic Resource
    Electronic Resource
    A quantitative method for thein vitro study of sounds produced by prosthetic aortic heart valves Part I: analytical considerations (1984)
    Springer
    Medical & biological engineering & computing 22 (1984), S. 32-39 
    Details
    ISSN: 1741-0444
    Keywords: Fast Fourier transform ; Noninvasive diagnosis ; Prosthetic heart valve ; Sound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A method is presented for analysing sounds producedin vitro by prosthetic aortic heart valves, and a one-dimensional harmonic model is described. Procedures for estimating physical parameters of the model are outlined for the case of transient and nontransient sounds, and a computational method is described for making comparisons between two general sounds. The fast Fourier transform provides a satisfactory means for the basic transformation to the frequency domain. Useful representations of the acoustical information that are considered are the original time and amplitude plots. power-density spectra, power-distribution functions, a three-dimensional surface of power-frequency-time, sections of these three-dimensional surfaces, and a three-dimensional power-distribution surfaces. Note is made that each representation is useful for indicating specific acoustical characteristics which may be important when either comparing or describing sounds. The spectra provide an accurate means for estimating the parameters of the model and provide clearer comparisons when compared to the time-amplitude plots. This fact is most clearly shown by the three-dimensional powerdifference surface. This surface provides a very convenient means for the overall comparison of two sounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443743
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  • 7
    Electronic Resource
    Electronic Resource
    A quantitative method for thein vitro study of sounds produced by prosthetic aortic heart valves Part II: an experimental, comparative study of the sounds produced by a normal and simulated-abnormal Starr-Edwards series 2400 aortic prosthesis (1984)
    Springer
    Medical & biological engineering & computing 22 (1984), S. 40-47 
    Details
    ISSN: 1741-0444
    Keywords: Fast Fourier transform ; In vitro comparison ; Sound ; Starr-Edwards 2400 prosthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A comparative study was made of the sounds produced by a normal Starr-Edwards 2400 aortic valve prosthesis with those produced by the same valve but having a simulated overgrowth at the apex of the struts. Comparisons were made over the entire cardiac cycle for time and amplitude, power-density spectra, power-distribution spectra, power-distribution surfaces associated with individual valves, and three-dimensional power-distribution-difference surface. Power-density spectra were compared for portions of the cycle corresponding to the opening, systolic, and closing sounds of the valve. Physical parameters of an acoustical model were estimated from the power-density spectra. The results showed that each comparison gave information pertinent to the simulated malfunction. Opening. systolic and closing sounds, respectively, were different for each valve. The opening sound of the abnormal valve displayed a much lower frequency. Systolic sounds for the two valves were similar in frequency, but the normal valve produced more total power for this sound. The closing sound of the abnormal valve occurred later than that of the normal valve. These differences were more clearly seen when viewed in the frequency domain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443744
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  • 8
    Electronic Resource
    Electronic Resource
    A quantitative method for thein vitro study of sounds produced by prosthetic aortic heart valves Part III: an experimental comparative study of the sounds produced by normal and simulated-abnormal Smeloff aortic prostheses (1984)
    Springer
    Medical & biological engineering & computing 22 (1984), S. 48-54 
    Details
    ISSN: 1741-0444
    Keywords: Fast Fourier transform ; In vitro comparison ; Smeloff prosthesis ; Sound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Anin vitro study was made of the sounds produced by a normal, Smeloffaortic-valve prosthesis and compared for the entire cardiac cycle with the same valve having a simulated overgrowth on the upstream struts. Time and amplitude information, power-density spectra, power-distribution functions, and three-dimensional power-frequency-time surfaces were compared. Power-density spectra and power-distribution functions were compared in more detail for those portions of the cycle corresponding to the opening, systolic, and closing sounds of the valve. Parameters for the acoustical model were estimated from these power-density spectra. All results were then compared and discussed in terms of the physical changes in the valve. Each comparison gave useful information about the simulated malfunction. Opening, systolic, and closing sounds were different for each case. More power was displayed in the opening sound of the abnormal valve and the systolic sound was early. The closing sound of the abnormal valve had a lower frequency content, and a diastolic sound was observed only for the abnormal valve. Use of the frequency domain gave additional understanding of differences in performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443745
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  • 9
    Electronic Resource
    Electronic Resource
    Waveform analysis for the detection of airways obstruction in man (1984)
    Springer
    Medical & biological engineering & computing 22 (1984), S. 481-485 
    Details
    ISSN: 1741-0444
    Keywords: Aiways obstruction ; Amplitude spectrum ; Deep and rapid manoeuvre ; Fast Fourier transform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The mathematical analysis of respiratory signals has been suggested as a safe noninvasive method for the diagnosis of airways obstruction in man. It involves (i) recording the respired air volume against time waveform for the deep and rapid breathing manoeuvre, (ii) digitising the analogue waveform and (iii) processing the data on a digital computer. The fast Fourier transform technique is used to process the data to yield the amplitude/power spectrum of the waveform. It is shown that, with the aid of the spectrum, it is possible to distinguish between the breathing waveform of a patient suffering from airways obstruction (AWO) and a normal subject (free from AWO). The paper presents results based on a study of the analysis of the respiratory volume signals of 85 subjects (both normals and patients) and suggests that this technique be used as a mass screening diagnostic test for AWO. The processing of the signals and subsequent diagnosis can be performed online with the aid of a microprocessor-based computer system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443859
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