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  • Rat  (71)
  • sediments  (44)
  • Angiosperms  (38)
  • 42.65  (37)
  • Springer  (190)
  • Blackwell Publishing Ltd
  • 1980-1984  (190)
  • 1925-1929
  • 1982  (101)
  • 1981  (89)
Collection
Keywords
Publisher
  • Springer  (190)
  • Blackwell Publishing Ltd
Years
  • 1980-1984  (190)
  • 1925-1929
Year
  • 1
    Electronic Resource
    Electronic Resource
    An anomalous correlator of resonantly scattered light (1982)
    Springer
    Applied physics 27 (1982), S. 83-91 
    Details
    ISSN: 1432-0649
    Keywords: 42.65 ; 06 ; 35 ; 07.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The space-time properties of the correlator of the light intensities scattered from resonant atoms are studied. It is shown that in measuring such a correlator by the method of optical shifts, an appreciable contribution appears from the anomalous correlator of the scattered field amplitudes. It is simple to observe this correlator in the field of a standing wave by measuring the correlation of oppositely scattered rays. The spectral and polarization properties of such a correlator are studied. Its investigation is of interest for high-resolution spectroscopy because it allows information to be obtained on the natural width of a line in conditions of strong Doppler broadening. It is important to stress that this is possible in a linear approximation with respect to the strength of the external field in contrast to the methods of laser spectroscopy based on nonlinear effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697554
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  • 2
    Electronic Resource
    Electronic Resource
    Nonlinear optical processes I (1982)
    Springer
    Applied physics 28 (1982), S. 142-149 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697839
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  • 3
    Electronic Resource
    Electronic Resource
    Temporal analysis of a mode-locked Nd-glass laser by four-wave mixing (1982)
    Springer
    Applied physics 29 (1982), S. 263-267 
    Details
    ISSN: 1432-0649
    Keywords: 42.55 ; 42.65 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The duration, shape, and background intensity level of pulses of a passively modelocked Nd-glass laser are determined by noncollinear phase-matched four-photon frequency mixing of time-separated fundamental and second-harmonic pulses in a KI crystal. The pulse shape is found to be slightly asymmetric with slower trailing than rising parts. The background intensity level before and behind the main pulse is about 5¢10−6 the peak pulse intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689185
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  • 4
    Electronic Resource
    Electronic Resource
    Phase conjugation (1982)
    Springer
    Applied physics 28 (1982), S. 155-162 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697841
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  • 5
    Electronic Resource
    Electronic Resource
    CARS spectroscopy of SF6 and UF6 (1982)
    Springer
    Applied physics 29 (1982), S. 255-262 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract CARS spectra of thev 1-band of SF6 and UF6 performed under (static) cell conditions and under supersonic jet expansion have been recorded. The cooling behavior in supersonic jet expansions has been demonstrated for both gases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689184
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  • 6
    Electronic Resource
    Electronic Resource
    Nonlinear spectroscopy (1982)
    Springer
    Applied physics 28 (1982), S. 81-91 
    Details
    ISSN: 1432-0649
    Keywords: 42.65 ; 07.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697833
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  • 7
    Electronic Resource
    Electronic Resource
    Four-wave mixing in alkali halide crystals and aqueous solutions (1982)
    Springer
    Applied physics 29 (1982), S. 37-42 
    Details
    ISSN: 1432-0649
    Keywords: 42.65 ; 61.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Noncollinear phase-matched nonresonant four-photon frequency mixingω p+ω p−ω L→ω s in crystals and aqueous solutions of LiCl, CsCl, KF, and KI is studied. The concentration of the aqueous solutions is varied between 0.5 mol/l and saturation. Picosecond laser pulses of a mode-locked Nd-glass laser are applied as pump pulses. The energy conversion of laser light at frequencyω L to frequencyω S is measured and the nonlinear susceptibilities χ(3) are calculated. The dependence of the hyperpolarizabilities on concentration is analysed and gives information on the solute-solvent interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694367
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  • 8
    Electronic Resource
    Electronic Resource
    Bistability (1982)
    Springer
    Applied physics 28 (1982), S. 131-141 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697838
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  • 9
    Electronic Resource
    Electronic Resource
    Laser plasmas (1982)
    Springer
    Applied physics 28 (1982), S. 290-296 
    Details
    ISSN: 1432-0649
    Keywords: 50 ; 34 ; 32.50 ; 42.60 ; 61.80 ; 62 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697858
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  • 10
    Electronic Resource
    Electronic Resource
    Nonlinear laser spectroscopy (1982)
    Springer
    Applied physics 29 (1982), S. 160-169 
    Details
    ISSN: 1432-0649
    Keywords: 32 ; 35 ; 42.65 ; 32 ; 33 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688659
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  • 11
    Electronic Resource
    Electronic Resource
    Dynamical nonlinear optics and bistability (1982)
    Springer
    Applied physics 29 (1982), S. 169-175 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688660
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  • 12
    Electronic Resource
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    Picosecond pulses and applications (1982)
    Springer
    Applied physics 29 (1982), S. 176-179 
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    ISSN: 1432-0649
    Keywords: 42.65 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688661
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  • 13
    Electronic Resource
    Electronic Resource
    Resonant coherent transients in a gas in the standing-wave field (1981)
    Springer
    Applied physics 26 (1981), S. 67-72 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Polarization decay in the presence of a standing electromagnetic wave field at a Doppler broadened transition is investigated theoretically and experimentally. It is shown that in the direction opposite to the propagation of an excited pulse the polarization decays at a transition frequency rather than at an exciting field frequency as usual. This permits the use of transients both in studies of relaxation processes and in Doppler-free super-high resolution spectroscopy. A resonant coherent transient has been used in measurements of relaxation decay constants of a dipole moment for collisions in SF6 (λ=10.6μm). This method has enabled one to resolve reliably the structure of theQ(38) transition (λ=10.6μm) of theF 1 0 +E 0=F 2 0 line of the 0→v 3 band in SF6 within a Doppler absorption line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702690
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  • 14
    Electronic Resource
    Electronic Resource
    Dynamics of the nonlinear four-wave mixing interaction (1981)
    Springer
    Applied physics 26 (1981), S. 105-110 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present an analysis of the impulse response of four-wave mixing, in the case where the “two-photon term” of the nonlinear susceptibility is dominant. The nonlinear interaction itself will be considered to be steady state. The conditions of negligible pump depletion are considered first. It is shown that the reflected beam has only the character of perfect phase conjugation if the pulse length is longer than the medium length, and the latter is short compared to the characteristic distance of the problem. The “weak-pulse” approximation involving only two coupled equations is compared to the exact four-wave solution, when the medium thickness approaches the critical oscillation threshold. Finally, the stability and existence of steady-state solutions is analyzed for very long media (compared with the oscillation length).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01284910
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  • 15
    Electronic Resource
    Electronic Resource
    CARS studies of vibrationally excited nitrogen at low pressures (1982)
    Springer
    Applied physics 29 (1982), S. 31-36 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Coherent anti-Stokes Raman spectroscopy (CARS) was used to measure the vibrational temperature of microwave-excited nitrogen in a N2−CO−He mixture. CARS spectra, originating from the N2-vibrational levelsv=0 up tov=3, have been recorded by both narrowband scanning of the resonance region as well as by broadband OSA detection. For the microwave-excited N2 molecules a vibrational temperatureT v (N 2 = (2130±110K) and a lower limit of detection forN 2(v = 3) = 1.2 x 1015 cm−3 was established. The CARS results were independently confirmed by simultaneously recorded and spectrally resolved CO infrared fluorescence studies.
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    URL: http://dx.doi.org/10.1007/BF00694366
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  • 16
    Electronic Resource
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    Low threshold optical bistability with optical pumping (1982)
    Springer
    Applied physics 29 (1982), S. 79-87 
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    ISSN: 1432-0649
    Keywords: 42.50 ; 42.65 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract By use of circularly polarized light we have exploited optical pumping within the Zeeman sublevels of the ground state to obtain optical bistability in sodium vapours with low threshold power (around 1 mW) and a wide tuning range (〉12 GHz). Experimental results are presented for different conditions of operation and compared to computer calculations, that include propagation effects and inhomogeneous broadening, based on a three-level atomic model that accounts for optical pumping.
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    URL: http://dx.doi.org/10.1007/BF00692767
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  • 17
    Electronic Resource
    Electronic Resource
    Laser-induced polarization anisotropy in In three-level system (1982)
    Springer
    Applied physics 27 (1982), S. 141-144 
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    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We observed a polarization change induced by laser radiation in the Raman-type three-level atom In in the presence of Ar. The observed two components in the polarization change spectrum of the probe beam correspond to the resonant Raman scattering and the luminescence processes in the spontaneous emission. The dependence of their intensities on the collision with Ar atoms agrees with the theory.
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    URL: http://dx.doi.org/10.1007/BF00694639
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  • 18
    Electronic Resource
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    A nonlinear correlation method using multiphoton ionization for the measurement of uv ultrashort pulses (1982)
    Springer
    Applied physics 28 (1982), S. 25-29 
    Details
    ISSN: 1432-0649
    Keywords: 42.65 ; 06.60.Jn ; 32.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new nonlinear correlation method which makes it possible to measure the duration of uv ultrashort pulses has been proposed. In this method the multiphoton ionization of gases is used as a nonlinear process and the ion current caused by the process is detected. We have also experimentally demonstrated its usefulness in the uv region by observing the second- and the third-order auto-correlation profiles of picosecond pulses at 2661 Å (the fourth harmonic of a mode-locked YAG laser), using NO and Xe gases, respectively.
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    URL: http://dx.doi.org/10.1007/BF00693888
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  • 19
    Electronic Resource
    Electronic Resource
    Dynamical NL optics, bistability (1982)
    Springer
    Applied physics 28 (1982), S. 92-101 
    Details
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697834
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  • 20
    Electronic Resource
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    Applications of ps-pulses (1982)
    Springer
    Applied physics 28 (1982), S. 246-254 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.65 ; 34 ; 42.55 ; 42.70 ; 78
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697852
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  • 21
    Electronic Resource
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    Vibrational relaxation of dye molecules investigated by ultrafast induced dichroism (1982)
    Springer
    Applied physics 27 (1982), S. 115-122 
    Details
    ISSN: 1432-0649
    Keywords: 33 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Theoretical and experimental data are presented on the propagation of picosecond pulses in weakly excited dye solutions. It is shown that the so called “coherence peak” of the induced dichroism observed at short delay times depends on the vibronic relaxation and the excited state absorption of the dye molecules. Interpretation of the experimental results is considerably facilitated at low excitation level. The vibrational relaxation time in theS 1 state of phenoxazone 9 was measured to be τ v =0.8±0.3 ps, 0.7±0.2 ps and 0.7±0.2 ps, respectively, for the solvents dioxane, solid polystyrene and CCl4. For rhodamine 6 G in ethanol we find τ v =0.5±0.2 ps.
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    URL: http://dx.doi.org/10.1007/BF00694635
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  • 22
    Electronic Resource
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    Nonlinear processes II (1982)
    Springer
    Applied physics 28 (1982), S. 262-268 
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    ISSN: 1432-0649
    Keywords: 78 ; 42.65 ; 61.40 ; 73 ; 73.20 ; 82 ; 81.15
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697854
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  • 23
    Electronic Resource
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    Harmonic mixing in a cosine potential for large damping and arbitrary field strengths (1982)
    Springer
    Applied physics 28 (1982), S. 335-339 
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    ISSN: 1432-0649
    Keywords: 72.20 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A complete numerical treatment is given for the dc harmonic mixing signal of two ac electric fields of frequences ω and 2ω. Mixing occurs due to a charged Brownian particle in a cosine pinning potential. Nonlinear responses to pinning potential strength as well as to ac field strengths are computed using the method of matrix continued fraction expansion within a Smoluchowski treatment. Relevant ranges of all the parameters of the model are considered, i.e. strength of pinning potential, fundamental frequency, the two ac field strengths as well as temperature and the phase relation between the exciting fields. It is found that strong deviations from the predictions of cubic response theory occur at scaling field strengths sufficient to give the charge an energy gain ofk BT when it traverses one potential trough. For even larger field strengths the harmonic mixing signal falls off rapidly. Higher order than cubic responses also show up in a peculiar dependence of the mixing signal on the phase angle between the ac fields.
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    URL: http://dx.doi.org/10.1007/BF00686363
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  • 24
    Electronic Resource
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    Laser cooling of trapped particles II (1981)
    Springer
    Applied physics 24 (1981), S. 71-84 
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    ISSN: 1432-0630
    Keywords: 32 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We consider cooling of a trapped particle in the limit when the position and velocity variables do not change adiabatically. The slowly varying quantity in a harmonic trap is then the energy, and a representation based on oscillator eigenstates is used. For large excitation, fast particles, a Fokker-Planck expansion is obtained which is valid when our adiabatic description breaks down. Estimates of the initial cooling rate are given and compared with earlier results. Our treatment requires a large number of oscillator states to be coupled by each one-photon process, and in this limit the diffusion will make the expansion invalid towards the end of the cooling; our physical interpretation is that particles leak out of the trap. The opposite case, the Lamb-Dicke regime, is advantageous for cooling experiments, and then a difference equation replaces the Fokker-Planck equation of the present paper.
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    URL: http://dx.doi.org/10.1007/BF00900402
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  • 25
    Electronic Resource
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    Possibility of fast deep cooling of atomic or molecular gases by laser radiation (1981)
    Springer
    Applied physics 24 (1981), S. 119-120 
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    ISSN: 1432-0630
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A technique of fast deep cooling of atomic or molecular buffer gases by laser radiation is proposed. With Na vapor as a cooling agent interacting with a laser field a cooling time of about 10−3s and minimum temperature of about 25K can be attained.
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    URL: http://dx.doi.org/10.1007/BF00902266
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  • 26
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    Laser multiphoton and multistep photoionization of molecules and mass spectrometry (1981)
    Springer
    Applied physics 24 (1981), S. 89-106 
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    ISSN: 1432-0630
    Keywords: 33 ; 42.65 ; 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A review of laser-induced photoionization of polyatomic molecules and the application of this process in mass-spectrometry is presented. Combination of laser selective photoionization and mass spectral analysis of fragments as a promising tool for the detection of trace amounts of complex molecules is considered particularly.
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    URL: http://dx.doi.org/10.1007/BF00902263
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  • 27
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    A perturbative description of coherent multiphoton resonant processes (1981)
    Springer
    Applied physics 24 (1981), S. 349-355 
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    ISSN: 1432-0630
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We construct field equations and generalised Bloch equations for multiphoton processes involving the coherent interaction of a number of distinct electric fields with an arbitrary number of atomic eigenstates, and apply the equations to some physical examples. Transient stimulated hyper-Raman scattering, in the low-conversion regime and far from saturation, has been studied analytically. Assuming that the pump pulse interacts with the medium byn-photon absorption, we find expression for the intensity of the generated Stokes pulse.
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    URL: http://dx.doi.org/10.1007/BF00899733
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  • 28
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    A monochromatic and frequency stabilized cw source in the 5 μm region obtained by doubling the frequencies of a cw laser in tellurium (1981)
    Springer
    Applied physics 24 (1981), S. 21-22 
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    ISSN: 1432-0630
    Keywords: 42.60 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this paper we describe the construction of a monochromatic and frequency stabilized continuous wave (cw) source in the 5 μm region. It is built up by a cw single line, single-mode frequency and amplitude stabilized CO2 laser. This primary CO2 laser source is then frequency-doubled in a tellurium crystal using second harmonic generation (SHG). The obtained emission is monochromatic (half-width 50 kHz). The frequency can be varied discreetly from 4.6 μm to 5.5 μ depending on the CO2 laser line chosen.
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    URL: http://dx.doi.org/10.1007/BF00900391
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  • 29
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    Observation of Ramsey resonance absorption in three separated laser fields produced by a corner reflector (1981)
    Springer
    Applied physics 24 (1981), S. 11-12 
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    ISSN: 1432-0630
    Keywords: 42.65 ; 07.65 ; 33.90
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Experimental observation of optical Ramsey interference in saturated absorption of methane in a low-pressure gas cell with three spacially separated laser beams at 3.39 μm is reported.
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    URL: http://dx.doi.org/10.1007/BF00900389
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  • 30
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    Measurement of atomic parameters for the3 D 1 state of I–II (1981)
    Springer
    Applied physics 25 (1981), S. 31-34 
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    ISSN: 1432-0630
    Keywords: 35 ; 42.55 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The decay rates of the3 D 1 level of I–II and the 3s 2 level of neon have been measured by the magnetic-field power dip method. The decay rate at the zero-pressure limit is found to be 7.1 MHz/2π for the3 D 1 level. The collision cross-section for excited I ions with helium atoms equals 0.19×10−15 cm2.
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    URL: http://dx.doi.org/10.1007/BF00935388
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  • 31
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    Four-wave mixing and optical-field-induced helical structure in liquid crystalline materials (1981)
    Springer
    Applied physics 25 (1981), S. 49-56 
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    ISSN: 1432-0630
    Keywords: 42.65 ; 78.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Four-wave mixing with two circularly polarized counter-propagating waves inducing a helical birefringence structure can be used to measure a number of material parameters of a liquid crystalline medium. Application to a cholesteric substance is particularly interesting. A resonant effect is expected when the induced helix has a pitch coinciding with the natural helical pitch of the medium towards the isotropic → cholesteric transition. Field-induced shift in the transition temperature is also expected.
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  • 32
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    Optical frequency mixing in planar waveguides: Influence of crystal orientation (1981)
    Springer
    Applied physics 26 (1981), S. 185-190 
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    ISSN: 1432-0630
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Optical frequency mixing through nonlinear mode coupling in a planar waveguide, fabricated with a cubic or uniaxial dielectric, is discussed. A threewave interaction is examined and the optimum crystal orientations that lead to the highest efficiency are determined in those particular cases in which they do not depend on the field distribution of the modes. The analysis is carried out in detail for cubic crystals; sensitivity to misalignments is also studied and numerical results are reported.
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  • 33
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    Bistability of a CO2 laser with SF6 intracavity as an absorber: Transient effects (1981)
    Springer
    Applied physics 24 (1981), S. 45-48 
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    ISSN: 1432-0630
    Keywords: 42.55 ; 42.65 ; 64
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We investigated time-dependent effects related to the bistable operation of a CO2 laser with an intracavity nonlinear absorber (SF6). The response of the system to small perturbations was sensitively dependent on the operating laser line [P(12)→P(30)] of the 10.6 μm band. The narrow bistable region forP(12), due to a very narrow hysteresis loop, can be effectively utilized for optical switching, because of its pronounced sensitivity to variations in operational parameters. The maximum admissable beam blocking time (intracavity) for spontaneous return to lasing was measured forP(16), for a range of absorber pressures. This τm is related to the relaxation time of the upper level in the absorber.
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    Stimulated electronic Raman scattering in In vapor (1981)
    Springer
    Applied physics 24 (1981), S. 139-142 
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    ISSN: 1432-0630
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The tuning and threshold behaviors of 5P 1/2–5P 3/2 stimulated electronic Raman scattering in In vapor were investigated. The Stokes output intensity was limited by atom depletion process in the atomic density available for the measurement. The anti-Stokes radiation observed was studied in terms of the phase matching condition.
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    URL: http://dx.doi.org/10.1007/BF00902270
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    Laser cooling of trapped particles III: The Lamb-Dicke limit (1981)
    Springer
    Applied physics 24 (1981), S. 151-162 
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    ISSN: 1432-0630
    Keywords: 32 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this paper we consider the laser cooling of a trapped particle when the discrete nature of the quantum levels must be taken into account. We particularize the equations to the Lamb-Dicke limit when the oscillational, amplitude is much less than the optical wavelength. Then the quantum levels are coupled only to the neighbouring ones, and we can also find a small parameter to use for adiabatic elimination of rapidly varying terms. There emerges one rate equation for the probability distribution over the quantum states. The ultimate distribution is found to be of the Planckian type independently of the initial one. We solve the equation, generally and obtain the time evolution for an arbitrary initial distribution. In particular we look at an initially thermal, Poisson, or pure state distribution. For the thermal one we find that its shape is preserved during the cooling. The results are discussed.
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    Measurement of spin-flip raman gain, effectiveg-value and absorption of radiation under transient electric field conditions in insb (1981)
    Springer
    Applied physics 26 (1981), S. 115-124 
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    ISSN: 1432-0630
    Keywords: 42.65 ; 71.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We studied the change in Spin-flip Raman (SFR) gain and behaviour of the effectiveg-value as a function of pulsed electric fields inn-type InSb. The samples were held at 1.8 K in magnetic fields up to 1.4 T. Varying the strength of a pulsed electric field applied to the samples parallel to the magnetic field we found a direct correlation between the increase in electron temperature and the decrease of the Raman gain. Measurements of the Raman gain and spontaneous line width at different times after the starting of the electric pulse and during its fall time with a time resolution of 10 ns give no indication of a motional narrowing of the SFR line and of an increase of the gain during the decrease of the electric field pulse. These two predictions were made by Mooradian et al. (1972) to explain the observed transient increase of the intensity of the stimulated SFR Stokes radiation after an electric field across the sample was switched off. With our direct measurement of the Raman gain we could establish that at any time during and after the electric field pulse, the gain is less or equal to the value without electric field. In the electric field region from 0.3 V/cm up to 0.6 V/cm the Raman gain shows several maxima, originating from SFR scattering between different spin splitted conduction band levels. The electron distribution under pulsed electric field conditions give rise to a dynamically varying absorption mechanism of transmitted radiation. Time resolved transmission measurements explain the observed increase of stimulated SFR Stokes radiation during the switch-off time of electric field pulses by a lower absorption of radiation and not by a larger gain.
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    URL: http://dx.doi.org/10.1007/BF00616658
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    Stimulated raman scattering up to 10 orders in an optical fiber (1981)
    Springer
    Applied physics 24 (1981), S. 303-306 
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    ISSN: 1432-0630
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper describes the experimental investigation of stimulated Raman scattering obtained from a multimode fiber. 10 orders of stimulated Stokes scattering of wavelengths in the 546–702 nm region were obtained from a 480m multimode, low-loss, graded-index quartz fiber pumped by a 532 nm frequency-doubled YAG-Nd laser beam with a pulse duration of 7 ns, output power of 0.7 MW and repetition rates of 5 and 10 pps.
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    URL: http://dx.doi.org/10.1007/BF00899726
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    Correlation of45Ca incorporation with maturation ameloblast morphology in the rat incisor (1982)
    Springer
    Calcified tissue international 34 (1982), S. 211-213 
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    ISSN: 1432-0827
    Keywords: Rat ; incisor ; ameloblasts ; enamel ; 45Ca autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Rats were injected with45Ca and horseradish peroxidase to determine the patterns of45Ca incorporation into incisor enamel and the morphological types of the overlying maturation ameloblasts.45Ca autoradiography showed no differences in the patterns of incorporation into enamel between routinely embedded and freeze-dried specimens. Enamel overlaid by ruffle-ended ameloblasts was much more heavily labeled while that overlaid by smooth-ended ameloblasts showed only moderate labeling. The observations lend further support to the hypothesis that the ruffle-ended cells are very active in mineralizing enamel and that the smooth-ended cells are in a passive, restorative phase.
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    URL: http://dx.doi.org/10.1007/BF02411236
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    Effect of vitamin D deficiency on urinary excretion of connective tissue derivatives (hydroxyproline and glycosaminoglycans) in rats (1981)
    Springer
    Calcified tissue international 33 (1981), S. 177-180 
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    ISSN: 1432-0827
    Keywords: Connective Tissue ; Vitamin D deficiency ; Hydroxyproline excretion ; Glycosaminoglycan excretion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The urinary excretion of two connective tissue metabolites was studied in both control and vitamin D deficient rats. Hydroxyproline (HyPRO) excretion was determined after 2, 13 and 22 months (experiment I). It decreased with aging in animals receiving the control diet. On the contrary, this excretion increased as a function of age in vitamin D deficient animals. At the age of 22 months, HyPRO excretion was respectively 31 and 1708 µg a day in control and deficient animals. HyPRO and glycosaminoglycans (GAG) excretion was measured on a group of both control and vitamin D deficient rats at the age of 21 months (experiment II). These results confirm the high excretion of HyPRO in deficient animals. On the contrary, the GAG excretion was higher in control animals than in deficient ones, the mean excretion being respectively 412 and 234 µg a day.
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    Effects of chronic protein deficiency on skeletal development of young rats (1981)
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    Calcified tissue international 33 (1981), S. 223-231 
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    ISSN: 1432-0827
    Keywords: Protein deficiency ; Bone formation ; Skeletal development ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Protein deficiency was produced by freely feeding young rats a 1% lactalbumin diet for 12 weeks in order to study the effects of protein-calorie malnutrition on skeletal development. During the experiment the food and caloric intake and weight of the experimental animals decreased, while those parameters of the control animals progressively increased. However, when gross caloric intake was expressed as a function of the metabolic size of the animal, the caloric consumption was similar for both groups of animals. The protein-deficient animals exhibited micro-radiographic and histological features of an abnormal pattern of endochondral bone formation. Appositional bone growth, as determined by the daily appositional rate and the percentage of endosteal surfaces undergoing active bone formation, was significantly decreased in these animals, as was the percentage of periosteal surfaces exhibiting resorption. Both chemical analyses of the whole bone and electron probe microanalysis in the specific area of actively calcifying bone revealed no significant differences between the mineral content of control and protein-deficient animals. This study distinguishes the effects of protein deficiency from that of combined protein-calorie deprivation and demonstrates that the abnormal skeletal development observed was the result of a decrease in the quantity of bone formed rather than an altered mineral content.
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    Cytochemical studies on the ferritin-containing vesicles of the rat incisor ameloblasts with special reference to the acid phosphatase activity (1981)
    Springer
    Calcified tissue international 33 (1981), S. 51-55 
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    ISSN: 1432-0827
    Keywords: Rat ; Incisor ; Amelogenesis ; Acid phosphatase ; Ferritin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Acid phosphatase was localized in rat incisor ameloblasts without prior decalcification. Whenβ-glycerophosphate was used as the substrate, an intense reaction was observed in the supranuclear region of the secretory ameloblasts. But the reaction was dramatically reduced at the transitional stage and was very weak in the maturation ameloblasts. Whenp-nitrophenylphosphate was the substrate, the reaction product was consistently seen in the Golgi cisternae and the vesicular components of the ameloblasts at all stages of enamel development. These observations suggest that there are two acid phosphatases in ameloblasts. One is in the secretory ameloblasts and the other in the transition and maturation ameloblasts. X-ray micro-analyses for Fe and Pb showed that Fe and acid phosphatase were in the ferritin-containing vesicles at the later stage of enamel maturation. This evidence suggests that ferritin is digested in these vesicles for the release of the Fe pigment to the enamel. An increase in the number of intercellular bridges between ameloblasts was correlated with the dramatic decrease in height of ameloblasts at the pigment release stage. The ameloblast membranes were acid phosphatase positive at the intercellular bridges whenp-nitrophenylphosphate was the substrate. This activity may be involved in the reduction in the surface area of the ameloblast membranes.
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    Occurrence of actin-like protein in extracellular matrix vesicles (1982)
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    Calcified tissue international 34 (1982), S. 376-381 
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    ISSN: 1432-0827
    Keywords: Matrix vesicles ; Bone ; Actin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Preliminary indications of the occurrence of actin and myosin in crude matrix vesicle preparations have been reported previously. In the present study extracellular matrix vesicles from rat alveolar bone were isolated. They were further purified by a sucrose density gradient. SDS-polyacrylamide gel electrophoresis of the purified vesicles revealed the presence of a polypeptide with a molecular weight of 43 K daltons and with electrophoretic mobility identical to that of blood platelet actin. The limited proteolysis of both 43 K dalton vesicular polypeptide and actin byStaphylococcus aureus-V8-protease revealed three fragments with identical electrophoretic mobility. In addition, the vesicular preparations inhibited the activity of DNase I, a property typical of actin monomers. Filamentous material extracted from matrix vesicles showed ultrastructural features of F-actin. Reaction of this material with heavy meromyosin resulted in arrowhead formation, which is characteristic of acto-heavy meromyosin. The occurrence of actin in extracellular matrix vesicles may account for their budding from the osteoblastic plasma membrane, their possible motility in the matrix, and maintenance of the spherical shape.
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    Changes in oxytocin content in the magnocellular neurons of the rat hypothalamus following water deprivation or estrogen treatment (1981)
    Springer
    Cell & tissue research 216 (1981), S. 47-55 
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    ISSN: 1432-0878
    Keywords: Oxytocin ; Paraventricular nucleus ; Supraoptic nucleus ; Anterior commissural nucleus ; Immunohistology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of water deprivation or estrogen treatment on the oxytocin content of rat hypothalamic cells was examined using a quantitative immunohistological technique. Oxytocin-containing cells were visualized using the immunoperoxidase technique of Sternberger and a primary antiserum directed against oxytocin. The optical density of the darkest 3.2 μm diameter spot in the cytoplasm of a cell was used as a measure of the oxytocin content of that cell. Water deprivation produced a significant decrease in anti-oxytocin staining in the anterior commissural nucleus of males and females. There was a similar decrease in the paraventricular nucleus of males, but not in the paraventricular nucleus of females or the supraoptic nucleus of either males or females. Estrogen treatment of ovariectomized female rats produced a fall in anti-oxytocin staining in the anterior commissural, but not paraventricular or supraoptic nuclei.
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    Correlative ontogenetic development of catecholamine- and LHRH-containing nerve endings in the median eminence of the rat (1981)
    Springer
    Cell & tissue research 216 (1981), S. 31-38 
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    ISSN: 1432-0878
    Keywords: Median eminence ; Rat ; Ontogeny ; LHRH ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ontogenetic development of catecholamine (CA)-and LHRH-containing nerve endings in the median eminence of the rat was investigated by combining fluorescence histochemistry and immunohistochemistry in the same tissue section. LHRH-terminals appeared earlier than CA-terminals and were already detectable in the lateral part of the external layer of the central ME on the first day after birth. CA-nerve endings were first seen in a corresponding region of the ME on the seventh postnatal day. At this stage both types of terminals showed the earliest manifestation of a correlative pattern of their distribution. Subsequently the development of both types of nerve endings proceeded rapidly, and at 14 days their distribution pattern corresponded to that in adult animals. The authors conclude that at this stage the CA-neurons play a constant and significant role in the release of LHRH into the portal capillaries. The correlation between both types of nerve endings and the ontogenetic development of the capillary plexuses of the hypophysial portal system is discussed.
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    Effects of norepinephrine and dibutyryl adenosine 3′, 5′-cyclic monophosphate on the ultrastructure of pineal cells in monolayer culture (1981)
    Springer
    Cell & tissue research 216 (1981), S. 181-191 
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    ISSN: 1432-0878
    Keywords: Pineal gland ; Monolayer culture ; N-acetyl transferase ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To determine how neural influences control the function of the pineal gland, morphological and biochemical relationships after pharmacological treatment have been studied in rat pineal cells in monolayer cultures. Norepinephrine (NE) and dibutyryl cyclic 3′,5′-adenosine monophosphate (dBcAMP) treatment of cells that had been in culture for 5 and 21 days produced a stimulation in the enzyme activity of serotonin N-acetyl transferase, an enzyme important in indole synthesis. NE and dBcAMP also produced morphological changes which were dependent on the time of cells in culture. When 5 day-cultures were treated with NE and dBcAMP, light and dark cells were noted and endoplasmic reticulum increased and became more organized. Only dBcAMP treatment at 5 days produced an increase in dense granules and an elongation of cytoplasmic processes. Treatment of 21 day-cultures with dBcAMP also produced an increase in cytoplasmic processes while treatment with NE produced an increase in the synaptic ribbons and clear vesicles within the processes.
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    The effect of a liquid elemental diet on cell proliferation in the colon of rats (1981)
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    Cell & tissue research 216 (1981), S. 221-225 
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    ISSN: 1432-0878
    Keywords: Diet ; DNA synthesis ; Cell renewal ; Colon ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A liquid elemental diet (Vivonex) was given to rats for 6 days while control animals received a normal diet. At the end of the experiment each animal received one intraperitoneal injection of tritiated thvmidine at 8a.m. Animals from each group were killed hourly during the first 24h after the injection and the proliferative activity was studied by autoradiography of the mucosa of the colon using the labeled mitoses-wave method. The epithelial cell proliferation was significantly decreased in the colon of the Vivonex-fed animals.
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    Cerebellar intranuclear inclusions in chronically alcoholized rats (1981)
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    Cell & tissue research 216 (1981), S. 227-230 
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    ISSN: 1432-0878
    Keywords: Cerebellum ; Nuclear inclusions ; Alcohol ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Nuclear rods and sheets are described in neurons from the cerebellar cortex of rats alcoholized through ingestion of a 20 % aqueous ethanol solution over a period of 90 and 180 days. An eventual relationship between these nuclear inclusions and alcoholization is advanced.
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    Growth of aortic vascular smooth muscle cells in lowered oxygen tension (1981)
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    Cell & tissue research 216 (1981), S. 591-602 
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    ISSN: 1432-0878
    Keywords: Vascular smooth muscle ; Tissue culture ; Hypoxia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Primary cultures of vascular smooth muscle cells, isolated from rat aorta, were grown under normoxic (20% O2) and mildly hypoxic (5 % O2) conditions. Cells from both conditions were compared for growth characteristics, morphology, protein synthesis, lysosomal enzyme activity, and oxygen consumption. In no case was a consistently significant difference observed. These observations indicate that these cells can adapt or are adapted to mildly hypoxic conditions. Moreover, these results may indicate that the culture of vascular smooth muscle cells in mild hypoxia represents a closer approximation of in vivo growth conditions for these cells.
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    Role of estrogen and androgen in maintaining the preovulatory follicle (1981)
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    Cell & tissue research 216 (1981), S. 615-624 
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    ISSN: 1432-0878
    Keywords: Rat ; Preovulatory follicle ; Ultrastructure ; Estrogen ; Androgen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of Nitromifene citrate (CI 628), an antiestrogen, and Flutamide, an antiandrogen, on the ultrastructure and viability of the preovulatory follicle and granulosa cells were examined both in vivo and in vitro. In vivo administration of either antihormone induced degeneration within the granulosa cells. In some of the affected granulosa cells, the nuclear material was condensed while the cytoplasm and associated organelles were unaltered. In others, the density of the cytoplasm was reduced, the smooth endoplasmic reticulum was dilated but the nucleus remained unaltered. In vitro, either antihormone reduced granulosa-cell viability but the granulosa cells were twenty times more sensitive to CI 628 than to Flutamide. In addition, exposure to CI 628 induced nuclear condensation without affecting the cytoplasm, while Flutamide induced the deterioration of the cytoplasm without altering the nucleus. These observations suggest that: (1) both estrogen and androgens control the viability of the granulosa cells and thereby the follicle, (2) the action of estrogen and androgen is mediated through receptors within the granulosa cells since these antihormones prevent the nuclear uptake of their respective hormone, (3) the granulosa cells of preovulatory follicles appear to be more dependent on estrogen than on androgen, and (4) each steroid appears to have a specific role in maintaining the granulosa cell; estrogens control the integrity of the nucleus while androgens preserve the cytoplasmic organization of the granulosa cell.
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    Catecholamine-storing cells in the adrenal medulla of the pre- and postnatal rat (1981)
    Springer
    Cell & tissue research 217 (1981), S. 155-170 
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    ISSN: 1432-0878
    Keywords: Adrenal medulla ; Development ; Acetylcholinesterase ; Small granule cells ; Ultramorphology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the rat adrenal medulla was studied at the ultrastructural level with particular emphasis placed on early discrimination of different catecholamine-storing cells. The first granule-containing cells, phaeochromoblasts, were seen at day 15 of gestation migrating into the anlage of the cortex. These cells were characterized by a few small granules (80–120 nm in diameter) and a high nuclear to cytoplasmic ratio. Presumably due to differentiation into chromaffin cells, they were no longer present after the eighth postnatal day. Maturation of phaeochromoblasts was indicated by an increase in number and size of their storage granules and a decrease in the nuclear to cytoplasmic ratio. Noradrenaline and adrenaline cell types were first clearly discernible at day 21 of gestation. Another cell type, a giant cell, was also recognized at this stage. In the adult animal, noradrenaline, two morphologically different types of adrenaline, and small granule-containing cells were observed. By applying acetylcholinesterase histochemistry, it was found that at day 17 of gestation a small population of granule-storing cells showed strong positive staining in the endoplasmic reticulum. In the adult animal this cell type was further characterized by small-storage granules. Other chromaffin cells began to show weak staining within the endoplasmic reticulum at day 19 of gestation. This staining appeared more frequently within adrenaline than noradrenaline cells. However, even in the adult animal many cells of both types were completely negative. It is concluded that acetylcholinesterase histochemistry is a useful method for early discrimination of small granule-containing cells in the developing rat adrenal medulla.
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    Terminal sprouting in rat sternocostalis muscle following partial denervation (1981)
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    Cell & tissue research 217 (1981), S. 189-198 
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    ISSN: 1432-0878
    Keywords: Rat ; Sternocostalis muscle ; Partial denervation ; Motor neuron sprouting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sternocostalis muscle of the rat was examined at one to five days after partial denervation and levels of terminal sprouting were assessed. The removal of one intercostal nerve caused localised degeneration which did not extend more than a few muscle fibres deep into the field of distribution of the adjacent nerve. Terminal sprouting was clearly seen at 24 h after operation and did not appear to develop further up to five days. There was no difference in the sprouting responses to section of either intercostal nerve 2, 4 or 5. There was, however, a decrease in the response with increasing distance from the cut nerve. No sprouting response was observed in the contralateral muscle. Comparison of sprouting levels of B and C type end plates revealed a greater percentage of C type end plates with sprouts. However, the response of B type end plates, considered in relation to the levels of spontaneous sprouting, was greater than that of C type end plates.
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    Effects of tunicamycin on the hypothalamo-neurohypophysial system of the rat (1981)
    Springer
    Cell & tissue research 217 (1981), S. 199-210 
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    ISSN: 1432-0878
    Keywords: Hypothalamus ; Neurohypophysis ; Neurophysin ; Secretion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intracisternal injections of tunicamycin, an inhibitor of glycosylation, decreased the incorporation of [35S]cysteine into the neurophysins in the rat neurohypophysis. Histochemical and immunocytochemical studies showed that there was no concomitant decrease in the amount of secretory product in the perikarya of the hypothalamo-neurohypophysial neurones. Indeed there was an increase, although this was not associated with neurosecretory granules as judged electron-microscopically. Tunicamycin led to the formation of socalled “colloid droplets” which were immunopositive and of which the ultrastructural correlates appeared to be product-filled dilatations of the rough endoplasmic reticulum. The observations are interpreted to suggest that glycosylation plays a rôle in the packaging of secretory material in the hypothalamo-neurohypophysial system.
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    Interrelations between neural elements and tanycytes during the perinatal period of the rat (1981)
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    Cell & tissue research 215 (1981), S. 635-641 
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    ISSN: 1432-0878
    Keywords: Hypothalamo-hypophysial system ; Rat ; Supraependymal axons ; Ontogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study has utilized a correlative scanning-transmission electron microscopic technique to examine interrelations between neural elements and differentiated tanycytes and to identify supraependymal cells in the ventral region of the 3rd ventricle during the perinatal period in the rat. From the 18th day of fetal life monoaminergic and/or peptidergic axons penetrate into the ventricle between the tanycytes. After birth, they form an extensive network covering the surface of the infundibular recess. The axons possess morphological characteristics suggestive of neurohormone secretion. From the 20th day of prenatal life subependymal axons begin to “innervate” the tanycytes. Supraependymal cells differ in their shape and ultrastructure, but all of them bear resemblance to macrophages, as they contain numerous lysosomes and phagosome-like bodies.
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    Ultrastructural study of electrophysiologically identified neurones in the paraventricular nucleus of the rat (1981)
    Springer
    Cell & tissue research 216 (1981), S. 503-512 
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    ISSN: 1432-0878
    Keywords: Paraventricular neurones ; Alcian-blue labelling ; Ultrastructure ; Electrophysiology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characterization of electrophysiologically identified neurones of the rat paraventricular hypothalamic nucleus was performed with extracellular labelling technique. The extracellularly recorded neurones are labelled with an electrophoretic deposit of alcian blue contained in the recording micropipette. The neurone thus labelled takes on a dark and shrunken appearance which enables its detection among neighbouring cells without, however, concealing its main morphological characteristics. 1) Spontaneously firing neurones, invaded by an antidromic action potential elicited by electrical stimulation of the neurohypophysis, were identified as magnocellular cells containing dense-cored vesicles of 200–250 nm in diameter. Dense-cored vesicles were not found in the antidromically activated neurones devoid of spontaneous activity. 2) Trans-synaptically activated neurones in the PVN or in its dorso-lateral edge were small cells devoid of dense secretory vesicles. 3) PV neurones in which neurohypophysial stimulation evoked no response, contained small, dense vesicles (100 nm in diameter) comparable with those found in parvocellular peptidergic neurones.
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    Morphological studies on neuroglia (1981)
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    Cell & tissue research 216 (1981), S. 569-580 
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    ISSN: 1432-0878
    Keywords: Glial response ; Chemical lesion ; Kainic acid ; Hippocampus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cellular response of non-neuronal elements of the pyramidal cell layer of the rat hippocampus, especially the area CA 3, was observed electron microscopically following destruction of this formation by means of intraventricular administration of kainic acid (KA). The neuroglial cell types responding to the KA-induced lesion included astrocytes and the “microglia-like reactive cells”. In addition, numerous brain macrophages appeared in the damaged area CA 3. Oligodendrocytes and pericytes revealed no morphological changes. Swollen astrocytes were seen in the KA-induced lesion during the early stage. Glial filaments gradually developed in the soma and cell processes of these cells. Brain macrophages were seen in the KA-induced lesion during the early stage; they gradually decreased in number with time. Numerous small cells displaying a dark nucleus appeared in the damaged area CA 3 during the first two days after the KA-administration, and gradually increased in number. During the later stage this cell type could hardly be distinguished from the intrinsic microglial cells. It is open to discussion whether this cell type originates from the intrinsic microglial cells or from the hematogenic monocytes; therefore it is designated as “microglia-like reactive cell” in the present study.
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    Biosystematic studies onCapsella bursa-pastoris (Brassicaceae): Enzyme polymorphism in natural populations (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 73-94 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Brassicaceae ; Capsella bursa-pastoris ; Isoenzyme polymorphism ; population analyses ; geographic variation ; heterozygosity ; breeding system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetic variability of natural populations ofCapsella bursapastoris in North- and Middle-Europe has been estimated by means of enzyme assays. Zymograms of 81 populations have been developed. 17 loci could be identified, and 8 of them can be heterozygous. Genetic variability is greater between populations than within. No correlation between actual population sizes and genetic heterogeneity could be detected. Some electromorphs shift their frequencies proportionally to increasing adversity of climatic conditions, some appear to be constant over the whole area, and others are characterized by an apparently irregular variation pattern. Marginal populations comprise a significantly higher proportion of heterozygous plants than central ones. Apart from this clinal variation pattern, a mosaic pattern, strongly related to habitat conditions, was observed: genetic heterogeneity is greater in more intensively disturbed sites. The pattern of genetic variation in natural populations ofCapsella bursa-pastoris is rather highly influenced by the breeding system.
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    The breeding system ofEmblingia (Emblingiaceae) (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 63-65 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Emblingia ; Emblingiaceae ; Sapindaceae ; Dodonaea ; Stylobasidaceae ; Stylobasium ; Gyrostemonaceae ; Anemophily ; entomophily ; autogamy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Emblingia is a short lived fire weed with a highly autogamous breeding system.
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    URL: http://dx.doi.org/10.1007/BF00983205
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    Vergleichende cytotaxonomische Untersuchungen anRanunculus seguieri und der Artengruppe desR. alpestris (Ranunculaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 47-60 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Ranunculaceae ; Ranunculus seguieri ; R. alpestris ; R. traunfellneri ; R. bilobus ; R. crenatus ; Relationship betweenR. seguieri andR. alpestris s. lat.: morphology ; crossing experiments ; chromosome numbers ; karyotypes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Morphological and cytological investigations as well as crossing experiments were carried out withRanunculus seguieri Vill. and 4 species of theRanunculus alpestris L. group (R. alpestris L.,R. traunfellneri Hoppe,R. bilobus Bertol.,R. crenatus Waldst. & Kit.). ForR. seguieri andR. alpestris, localities and distribution are given in addition to extensive diagnoses. A key to the species includes morphological characteristics and distribution data forR. traunfellneri, R. bilobus, andR. crenatus. New diagnostic characters are described. Crossing experiments betweenR. seguieri and the species of theR. alpestris group were unsuccessful. All 5 species have a chromosome number of 2n = 16, the record forR. bilobus is new. There is no statistically significant difference between the karyotypes ofR. seguieri andR. alpestris s. str. Nevertheless, according to morphological evidence and crossing experiments,R. seguieri is not closely related to theR. alpestris group.
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    A chemotaxonomical study of someBoraginaceae: pyrrolizidine alkaloids and phenolic compounds (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 127-134 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Boraginaceae ; Pyrrolizidine alkaloids ; phenolic compounds ; chemotaxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By means of thin layer chromatography pyrrolizidine alkaloids and phenolic compounds in some members of the familyBoraginaceae, subfamiliesHeliotropioideae andBoraginoideae, were studied. FromOmphalodes verna a main alkaloid was isolated with an isoretronecanol (or stereoisomeric) nucleus. The chemotaxonomical model ofTétényi forBoraginaceae based on fatty acids is generally supported, but relationships betweenHeliotropioideae andCynoglosseae appear to be closer, suggesting parallel developments from common ancesters.
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    Embryology ofEriocaulon setaceum (Eriocaulaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 175-188 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Eriocaulaceae ; Eriocaulon setaceum ; Embryology ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eriocaulon setaceum can be characterized by: young microsporangium wall with epidermis, endothecium (with fibrous thickenings), and glandular tapetum (uninucleate cells); pollen grains 3-celled, spiraperturate; embryo sac development according to the Polygonum type and with antipodal cyst; endosperm nuclear; embryo small, with incipient differentiation into cotyledonary and epicotylary loci; seed coat mainly from the inner layers of the integuments; pericarp 2-layered and membranous. Embryologically, theEriocaulaceae are nearer to theXyridaceae than to otherFarinosae. Their elevation to the rank of an order,Eriocaulales, therefore appears justified.
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    Microgeographic edaphic differentiation in allozyme polymorphisms of wild barley (Hordeum spontaneum, Poaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 287-292 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Hordeum spontaneum ; Allozymes ; microgeographic differentiation ; population genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozymic variation in proteins encoded by 22 loci was analyzed electrophoretically in 278 individual plants of wild barley,Hordeum spontaneum, the progenitor of cultivated barley, in four 100 meter transects, in Israel, each equally subdivided into basalt and terra rossa soil types. Significant differentiation according to soil was found in 9 alleles. Our results suggest that allozyme polymorphisms in wild barley are at least partly adaptive, and differentiate by edaphic natural selection rather than by stochastic processes, and/or neutrality of allozymic variants.
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    Genetic variation inSolanum pennellii: Comparisons with two other sympatric tomato species (1981)
    Springer
    Plant systematics and evolution 139 (1981), S. 11-45 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Solanaceae ; Lycopersicon ; Solanum pennellii ; Allozymes ; electrophoresis ; isozymes ; mating systems ; self-incompatibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic variation—primarily in 19 genetic loci of seven enzyme systems—was analyzed in accessions from various parts of the geographic range ofSolanum pennellii, which according to all tested biosystematic criteria behaves like a species ofLycopersicon. In comparison with the largely sympatricL. hirsutum andL. pimpinellifolium, this species exhibits the same trends of reduced allogamy and decreased genetic variation toward the north and south margins of its distribution, though to a much lesser degree; it does not exhibit their trends toward smaller flower size in the same peripheral regions. All three species agree to a considerable extent in the ranking of their tested loci in respect to degree of variablility; however, overall polymorphy is highest inS. pennellii. Except for the appearance of self-compatibility at its southernmost margin,S. pennellii is exclusively and rigidly self-incompatible. Alleles are distributed much more uniformly over the range than in the previously mentioned species, marginal and internal endemic mutants being much less abundant. A marked geographic disagreement is evident in regions of high and low variation. These differences in patterns of genetic variability are reconciled in terms of observed differences in mating systems, probable age of distributions, and adaptive strategies.
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    Eine neueTillandsia-Art aus Südmexico:T. kolbii (Bromeliaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 259-262 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Bromeliaceae ; Tillandsia subgen.Allardtia ; T. kolbii ; spec. nova ; Flora of Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new species ofTillandsia is described and discussed in regard to related species.
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    Ultrastructure of the stylar canal cells ofCitrus limon (Rutaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 263-274 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Rutaceae ; Citrus limon ; Style ; canal cells ; canal filling substance ; ultrastructure ; anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of the canal cells and the canal filling substance ofCitrus limon have been studied. At maturity the canal cells are very rich in cytoplasm. Their inner tangential walls lining the canal are much thickened and formed by two layers: the outer corresponds to the original wall, the inner is formed by subsequent deposition of abundant materials of different origin. This thickening occurs at the same time as the filling of the stylar canal. Both events are paralleled by considerable dictyosomic activity, the formation of a large amount of rough endoplasmic reticulum, and the incorporation of small cytoplasmic masses into the cell wall, due to plasmalemma evaginations. — The material in the stylar canal has a heterogeneous ultrastructure aspect and consists of polysaccharides, proteins and lipids; it presumably provides nutrients for the growing pollen tubes.
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    A comparative study of genomes in angiosperms (1982)
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    Plant systematics and evolution 139 (1982), S. 209-227 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Dicotyledons ; Monocotyledons ; DNA reassociation kinetics ; fast repeats ; repetitive DNA ; single copy DNA ; short period interspersion pattern ; slow repeats ; genome evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Angiosperms investigated by DNA/DNA reassociation studies were classified and tested for a taxonomic class- and subclass-specifity in a biometrical fashion. Monocotyledons and Dicotyledons differ significantly from each other with respect to a genomic parameter (U/R-ratio;U single copy DNA fraction;R = 1-U fraction of repetitive DNA). This difference is discussed from an evolutionary and molecular point of view.—Intercorrelations between the fraction of fast repeats, slow repeats, and single copy DNA can be detected. The amount of DNA organized in a short period pattern of interspersion is found to depend on the fraction of repetitive and single copy DNA. The number of DNA segments tandemly arranged in a short period pattern is linearly correlated withR/U-values. This correlation allows for a formula suitable for the estimation of the number of active genes in angiosperms. The analytical complexities of repetitive and single copy DNA are linearly correlated with the genome size of higher plants. The ratioU/R depends on the genome size of angiosperms in a hyperbolic fashion.
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    Heterochromatin and chromosome variation in cultivated species ofTulipa subg.Leiostemones (Liliaceae) (1982)
    Springer
    Plant systematics and evolution 139 (1982), S. 163-178 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliaceae ; Tulipa subg.Leiostemones ; Giemsa banding ; heterochromatin ; karyosystematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromosomes of several cultivatedTulipa species of subg.Leiostemones were examined in conventionally stained and C-banded preparations. The heterochromatin content varied from almost none to 45%. Several chromosome types were recognized with respect to chromosome morphology and heterochromatin distribution, and groups of species with common chromosome characteristics could be identified. These karyological relationships are discussed with respect to the groups formed on the basis of floral and bulb charateristics.
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    Resistenzphysiologische Grundlagen der evolutiven Kälteakklimatisation von Sproßpflanzen (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 145-180 
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    ISSN: 1615-6110
    Keywords: Coniferophytina ; Angiosperms ; Arecaceae ; Poaceae ; Quercus ; Citrus ; sclerophyllous trees ; mountain plants ; Acclimatation ; chilling resistance ; frost resistance ; stress ecotypes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gradations in cold resistance of plants with different latitudinal and altitudinal distribution, and the various categories of chilling and freezing resistance are hypothesized to be evolutionary steps of adaptive responses to increasing low temperature stress and annual seasonality. The gradual lowering of the critical phase transition temperature of biomembrane lipids, the capacity of persistent supercooling of tissues, and the development of a dormancy linked freezing-tolerance are considered to be essential mechanisms resulting in improved acclimatation to low temperature climates.
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    Differentiation of Fraction 1 protein in relation to age and distribution of Angiosperm groups (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 89-113 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Nicotiana ; Gossypium ; Lemnaceae ; Fraction 1 protein ; differentiation and age of taxa ; migration to Australia ; land connections ; long distance dispersal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fraction 1 protein (F-1-protein) (ribulose bisphosphate carboxy-lase-oxygenase) contained inLemnaceae has been evolving for at least 50 million years because fossils of these plants have been identified in strata belonging to the Upper Cretaceous. Electrofocusing F-1-protein resolves the large subunit polypeptides coded by extranuclear DNA and the small subunit polypeptides coded by nuclear DNA. Four differences affecting isoelectric points of the large subunit polypeptides and eight affecting the small subunit polypeptides are now present among eleven species representing the four genera comprising theLemnaceae. In comparison, four differences in the large and 13 in the small subunit polypeptides exist among 63 species ofNicotiana; four differences in the large and eight differences in the small subunit polypeptides exist among 19 species ofGossypium. The number of differences in F-1-protein composition being of the same order of magnitude for the generaNicotiana, Gossypium, and the familyLemnaceae, we infer that these Angiosperms are of similar antiquity. Nicotiana species indigenous to Australia and Africa contain F-1-proteins whose large subunit polypeptides are different but some of whose small subunit polypeptides are like those found in species from the Western Hemisphere. The same situation is found for the F-1-protein inGossypium. These results are in harmony with the view that species ofNicotiana andGossypium have arrived in Australia via former land connections between S. America, Antarctica, and Australia.
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    The tubular exine ofLauraceae andHernandiaceae, a novel type of exine structure in seed plants (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 139-146 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Magnoliidae ; Lauraceae ; Hernandiaceae ; Pollen morphology ; pollen ultrastructure ; Angiosperm phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pollen grains ofLauraceae andHernandiaceae are characteristic in having a tubular exine of ± microfibrillar structure. This is coated with a layer of medium electron-dense globules and very peculiar spines, made up of a substance differing from that of the exine. Such a pollen wall structure is otherwise unknown in seed plants and thus adds to the list of odd features erratically present in various taxa of the Ranalean complex.
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    Effect of allopolyploidy on the activity of selected enzymes inHibiscus (1981)
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    Plant systematics and evolution 138 (1981), S. 189-198 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Malvaceae ; Hibiscus acetosella ; H. asper ; H. surattensis ; H. radiatus ; andH. cannabinus ; Allopolyploidy ; evolution of dosage compensation ; alcohol dehydrogenase ; malate dehydrogenase ; leucine aminopeptidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mature seeds of diploid and tetraploidHibiscus species were analyzed for enzyme activity (alcohol dehydrogenase, malate dehydrogenase, leucine aminopeptidase), total protein content, DNA amount and dry weight. The recently formed tetraploid,H. radiatus, generally had enzyme and protein levels very similar to the sum of its progenitors, while the more ancient speciesH. acetosella had several lower levels. This difference may reflect the greater amount of timeH. acetosella has had to evolve dosage compensations.
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    Genetic determination of pappus part number in the annual hybridMicroseris B 87 (Asteraceae—Lactuceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 235-246 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Lactuceae ; Microseris ; Canalized numbers ; quantitative genetics ; evolutionary genetics ; pappus parts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ChileanMicroseris pygmaea has a ten-part paleaceous pappus while the CalifornianM. bigelovii has five pappus parts on each achene. Hybrids between the two species have between five and ten pappus parts with averages below 7.5. Hybrid B 87 has an F 1 average value of 6.7 pappus parts. 140 F 2 plants were raised from this hybrid, and 12 F 3 families were obtained by selfing from F 2 plants. One larger F 4 family has been raised. Pappus part number in all of these is still canalized between 5 and 10. Variation within these limits is genetically determined by a quantitatively acting polygenic system. Modeling of this system suggests that a minimum of four, but probably not many more, genes are involved. This opens the possibility of a complete genetic analysis of the system.
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    Seed and fruit anatomy ofCocculus hirsutus (Menispermaceae) (1981)
    Springer
    Plant systematics and evolution 139 (1981), S. 95-102 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Menispermaceae ; Cocculus hirsutus ; Seed ; fruit ; anatomy ; affinities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ovules ofCocculus hirsutus are anatropous, bitegmic and, crassinucellate. The fruit is drupaceous, black purple, and laterally compressed and has a pericarp demarcated into exocarp and endocarp. The seeds are curved around the basal bodies. Testa and tegmen cells are thin-walled and unspecialized. In the ripe seed the inner epidermis of the tegmen persists, whereas the entire testa and the outer layer of the tegmen degenerate. Relationships of theMenispermaceae toRanunculaceae, Berberidaceae, andLardizabalaceae are supported.
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    Der Knotenbau einigerRubiaceae (1981)
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    Plant systematics and evolution 139 (1981), S. 103-111 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Rubiaceae ; Nodal anatomy ; leaf base ; stipules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The leaf base vascularization in most of theRubiaceae corresponds to the unilacunar pattern with one complex trace. Only some species are known to have a trilacunar nodal pattern with three traces. In the unilacunar type one pair of smaller bundles separates from the complex lacunary leaf trace laterally, each soon forking into two arms: One arm becomes a marginal vein of the petiole, the other, besides supplying the stipules, forms a ± distinct vascular “bridge” within the cortex of the nodal flanks. In theRubieae this flank bridge develops as a very distinct vascular “ring” commissure out of which the whorled leaf-like appendages are vascularized; only the opposite true leaves receive their complex trace out of the lacunes directly. Axillary branches originate only from these true leaves.
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    Serologische Untersuchungen zur Gliederung derBrassicaceae (1982)
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    Plant systematics and evolution 140 (1982), S. 39-55 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Brassicaceae (Cruciferae) ; Alysseae ; Arabideae ; Brassiceae ; Heliophileae ; Hesperideae ; Lepidieae ; Pringleeae ; Sisymbrieae.—Serological systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The serological investigations support the opinion ofJanchen (1942) to combine the generaBunias, Isatis, andSisymbrium in the tribeSisymbrieae; Cheiranthus, Erysimum, andMatthiola in the tribeHesperideae; andBrassica, Crambe, Sinapis, andSuccowia in the tribeBrassiceae. They further underline the central position of theSisymbrieae and the isolated position of theHeliophileae. In accordance withEigner (1973) theBrassiceae are placed closer to theSisymbrieae than inJanchen; the same holds for thePringleeae. No serological justification could be found to uniteArabis andBarbarea in the tribeArabideae, andAlyssum andLunaria in theAlysseae. From the antigen-systems used among the representatives ofJanchen's Lepidieae the generaLepidium andNeslia show remarkable correspondence both toCamelina andThlaspi, but not toCochlearia which appears distant fromCamelina andThlaspi also.
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    The possible polyphyletic origin of copper tolerance inAgrostis tenuis (Gramineae) (1982)
    Springer
    Plant systematics and evolution 140 (1982), S. 109-117 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Gramineae (Poaceae) ; Agrostis tenuis.—Evolution ; Copper tolerance ; genotype-environment interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of increased copper concentration in solution on the rooting of seven copper tolerant populations ofAgrostis tenuis has been examined using the regression technique ofFinlay &Wilkinson (1963). Three types of response to increased copper concentration have been detected, and it is suggested that these reflect a different genetic control of copper tolerance in different populations.
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    Chemotaxonomical investigations of theSymphytum officinale polyploid complex andS. asperum (Boraginaceae): The pyrrolizidine alkaloids (1982)
    Springer
    Plant systematics and evolution 140 (1982), S. 279-292 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Boraginaceae ; Symphytum.—Pyrrolizidine alkaloids ; chemotaxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By means of thin layer chromatography in conjunction with mass spectrometry the pyrrolizidine alkaloid patterns derived fromSymphytum asperum, several cytotypes ofS. officinale agg. and the artificial hybrids of the former taxa, were compared. The obtained patterns were not essentially affected by variation in cytotype, harvesting times and -location of plants. Lycopsamine, acetyl-lycopsamine and symphytine or their isomers were generally found in theS. officinale cytotypes, echimidine and symphytine inS. asperum. The interspecific hybrids contained all alkaloids mentioned. The definite lack of echimidine in the 2 n=40 cytotype proves that it is conspecific withS. officinale and does not belong to a hybrid-swarmS. asperum × S. officinale with 2 n=48.
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    Sclerorhachis leptoclada (Asteraceae-Anthemideae), eine neue Art aus dem südlichen Khorasan (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 297-299 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae-Anthemideae ; Sclerorhachis leptoclada Rech. f. ; spec. nova ; Flora of Iran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A fourth species ofSclerorhachis, S. leptoclada Rech. f., has been discovered in S. Khorasan. It differs from the three known species by its tender habit, rosette leaves with few short segments, extremely reduced stem leaves, and very small heads.Sclerorhachis with its four vicarious species confined to the most arid parts of the Iranian highlands is believed to belong to the paleoxeromorphics (Rechinger 1952).
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    Heterochromatin and chromosome variation in cultivated species ofTulipa subg.Eriostemones (Liliaceae) (1981)
    Springer
    Plant systematics and evolution 139 (1981), S. 47-55 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Tulipa subg.Liliaceae ; Eriostemones ; Giemsa banding ; heterochromatin ; karyosystematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromosomes of several cultivatedTulipa species belonging to the subg.Eriostemones were examined using conventional staining and C-banding techniques. Most of the species have lightly banded chromosomes with heterochromatin content varying from nil to about 15%. The banding patterns of several taxa are described and discussed in regard to species relationships.
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    URL: http://dx.doi.org/10.1007/BF00983921
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    Zur systematischen Stellung der GattungProckia: Karyologie und Epidermisskulptur im Vergleich zuFlacourtia (Flacourtiaceae),Grewia (Tiliaceae) und verwandten Gattungen (1981)
    Springer
    Plant systematics and evolution 139 (1981), S. 57-76 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Flacourtiaceae:Prockia ; Flacourtia ; Idesia ; Lacistema ; Rawsonia ; Tiliaceae:Grewia ; Luhea ; Karyomorphology ; epidermis ultrastructure ; Chromosomes and systematics of tropical woody plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Detailed analyses of karyology and leaf morphology do not support relationships betweenFlacourtiaceae andTiliaceae. In spite of different chromosome numbers,Prockia (2n = 18),Flacourtia (2n = 22) andRawsonia (2n = 22) are very similar in karyomorphology, indicating a certain karyological uniformity withinFlacourtiaceae. Lacistema (2n = ca. 62) appears more isolated. On the other hand, theTiliaceae Grewia (2n = 18) andLuhea (2n = 36) have much in common and differ remarkably from the Flacourtiaceous genera. The salicoid leaf-teeth ofProckia are also found inIdesia, but never inTiliaceae. Epidermis ultrastructure reveals certain relationships betweenProckia andFlacourtia in contrast to the strongly differingGrewia. Idesia has a rare und unique epidermis sculpture. — Basic chromosome numbers and chromosomal evolution within theFlacourtiaceae are discussed.
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    Zwei neue Hybriden in der GattungEuphrasia (Scrophulariaceae) (1982)
    Springer
    Plant systematics and evolution 139 (1982), S. 319-322 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Scrophulariaceae ; Euphrasia ; E. alpina ; E. ×dilata ; E. hirtella ; E. kerneri ; E. picta ; E. rostkoviana ; E. tricuspidata ; E. ×trikoviana ; E. ×vestinensis ; hybrids ; chromosome numbers ; Flora of Italy
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract The following new hybrids are described:Euphrasia ×dilata = E. hirtella Jordan exReuter ×alpina Lam.;Euphrasia ×trikoviana = E. tricuspidata L. ×rostkoviana Hayne. The chromosome number ofEuphrasia tricuspidata L. has been established for the first time: 2n = 22.
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    URL: http://dx.doi.org/10.1007/BF00989335
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    DNA sequence organization and RNA complexity inMatthiola incana (Brassicaceae) (1982)
    Springer
    Plant systematics and evolution 140 (1982), S. 75-86 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Brassicaceae ; Matthiola incana.—DNA interspersion pattern ; Messenger RNA ; RNA complexity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The DNA of the cruciferMatthiola incana (Brassicaceae, Capparales) has been investigated for the pattern of sequence interspersion and RNA transcription. A short period pattern of interspersion (Xenopus-like interspersion pattern) is predominant (60%). Similar to a series of other Angiosperms (tobacco, soybean, parsley and some cereals) repetitive clusters orinter-se interspersion patterns of repetitive DNA occur inMatthiola genome and amount to 12%. From the hybridization of single copy DNA with poly(A)−-RNA and from cDNA/poly(A)+-RNA and cDNA/poly(A)−-RNA hybridizations a number of about 9,400 active genes can be estimated forM. incana seedlings. Both RNA constituents (poly(A)+-RNA and poly(A)−-RNA) contain mainly the same protein-coding mRNA sequences. Total mRNA is amounting to about 4% of theM. incana RNA population. A total of 1.2% (or about 30% of mRNA) of theM. incana RNA is represented by polyadenylated mRNA sequences. About 3.6% of single copy DNA hybridizes with poly(A)−-RNA. Approximately 7% of theM. incana genome, organized in a short period pattern of DNA sequence interspersion, is transcribed into RNA sequences (mRNA). About 6% of clustered repetitive DNA is expressed into RNA sequences such as rRNA and tRNA. Approximately 1.6 × 106 rRNA, 1.75 × 107 tRNA and 3.7 × 105 mRNA molecules are present perMatthiola seedling cell. The transcription rate of single rRNA and tRNA genes can be estimated to be about 1,400 or 1,100 copies per gene, respectively.
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    Alcohol dehydrogenase isozymes inGossypium hirsutum and its putative diploid progenitors: The biochemical consequences of enzyme multiplicity (1982)
    Springer
    Plant systematics and evolution 140 (1982), S. 141-149 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Malvaceae ; Gossypium hirsutum ; G. ramondii ; G. herbaceum ; G. arboreum.—Allopolyploidy ; alcohol dehydrogenase ; developmental homeostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electrophoretic variation in alcohol dehydrogenase (ADH) was examined in tetraploidGossypium hirsutum and its putative diploid progenitorsG. ramondii, G. herbaceum, and a close relative,G. arboreum. All the diploids had three isozymes, while strains of the tetraploidG. hirsutum had either 4 or 6. Each isozyme was eluted from starch gels and significant differences in activity were noted between several of the isozymes relative to pH, substrate, temperature and salinity. This suggests that an increase in enzyme heterozygosity can result in higher levels of developmental homeostasis, but it depends on the isozyme alleles involved.
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    Karyotype variation inAllium commutatum (Liliaceae s. lato) (1982)
    Springer
    Plant systematics and evolution 140 (1982), S. 179-189 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliaceae s. 1. ; Alliaceae ; Allium ampeloprasum agg. ; A. commutatum ; A. bourgeaui, A. porrum.—Karyosystematics ; Karyotype differentiation ; chromosome polymorphism ; B-chromosomes ; polyploidy —Flora of the Mediterranean. Aegaean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromosome numbers (2×, 3×, 4×), B-chromosomes, and variation among marker chromosomes inAllium commutatum Guss. was studied. These different chromosomal types exhibit distinct distribution patterns and a centre of variation has been located in the central Aegean area. A common origin ofA. commutatum, the Aegean endemicA. bourgeaui Rech. fil.,A. ampeloprasum L. and the cultivatedA. porrum L. is discussed.
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    The systematics ofLinum sect.Linopsis (Linaceae) (1982)
    Springer
    Plant systematics and evolution 140 (1982), S. 225-234 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Linaceae ; Linum sect.Linopsis—Evolution ; classification ; chromosome numbers ; heterostyly ; pollen morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract SectionLinopsis of the genusLinum is the largest and probably the most widespread of the five commonly recognized sections. Using a number of traits, but especially heterostyly, style union, development of false septa in the fruit, pollen morphology, and chromosome number, together with petal pigmentation, number of floral parts, and stigma shape, the section is divided into five subsections:Dichrolinum, with one series;Halolinum with one;Linopsis, with four;Keniense, with one; andRigida, with two. Of these, subsect.Keniense and two series are new, the remaining four subsections and four series are published in a new rank. The inferred relationships of all of the groups and the general distribution of each are discussed. The section ranges from southern Europe and the Mediterranean region to India, eastern and southern Africa and throughout much of North and South America. The primitive species of the section are believed to be in the Mediterranean region.
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    Bestimmung des Schleimgehaltes myxospermer Diasporen verschiedener Angiospermenfamilien (1982)
    Springer
    Plant systematics and evolution 141 (1982), S. 7-21 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Acanthaceae ; Asteraceae ; Cistaceae ; Brassicaceae ; Cucurbitaceae ; Euphorbiaceae ; Juncaceae ; Lamiaceae ; Linaceae ; Lythraceae ; Nyctaginaceae ; Plantaginaceae ; Poaceae ; Podostemaceae ; Polemoniaceae ; Scrophulariaceae ; Solanaceae ; Urticaceae ; Zygophyllaceae ; Mucilage content of myxospermatic diaspores ; extraction procedures ; swelling factors ; substructures of mucilages
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    Notes: Abstract The mucilage content of structurally differing myxospermatic diaspores from 49 species belonging to 19 families ofAngiospermae has been determined by applying various extraction procedures. The results demonstrate no obvious relationship between the size, mucilage quantity, and the swelling factor of the diaspores studied. Furthermore, mucilage producing structures and structural peculiarities of the mucilages themselves are elaborated.
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    Chromosome numbers and rust susceptibility as taxonomic criteria inRosaceae (1981)
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    Plant systematics and evolution 137 (1981), S. 23-38 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Rosaceae ; Uredinales ; Chromosome numbers ; rust susceptibility ; tribal classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract BothNeuradoideae andChrysobalanoideae seem rust-free. TheSpiraeoideae andPomoideae are heavily susceptible toGymnosporangium rusts. While thePrunoideae resemble theRosoideae in being vulnerable to attacks ofPuccinia species, they are additionally susceptible toTranzschelia andThekopsora, whereas theRosoideae are characteristically afflicted byPhragmidium.—It is suggested (a) to treat theChrysobalanoideae as a separate family (Chrysobalanaceae), (b) to transferDryas from theRosoideae-Potentilleae-Dryadinae to theRosoideae-Cercocarpeae, and (c) to divide theRosoideae into two main groups of tribes: (i) the rust-freeKerrieae andCercocarpeae with x = 9, and (ii) the rust-susceptiblePotentilleae, Ulmarieae, Roseae andSanguisorbeae with x = 7.
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    The evolutionary significance of multigermicity in the genusSpinacia (Chenopodiaceae) (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 57-61 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Chenopodiaceae ; Spinacia ; S. turkestanica ; S. tetrandra ; Reproduction ; multigermicity ; seedball ; dioecy ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The presence of multigerm seedballs in the chenopodiacious genusSpinacia is noted. In the wild, colonising, and “weedy” dioecious species,S. turkestanica andS. tetrandra, the distribution of a multigerm seedball could effectively overcome the problem posed by isolation of the sexes. The hypothesis is tested assessing the extent of intra-seedball progeny hybridisations and seed production in the two wild species. The success in seed production by intra-seedball progeny crosses suggests that the distribution of such seedball progeny groups permits not only a percentage survival under isolation of these dioecious plants, but also the colonisation of areas outside that of the parent populations.
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    The embryology ofEpipogium roseum (Orchidaceae) (1981)
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    Plant systematics and evolution 138 (1981), S. 1-7 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Epipogium ; E. roseum ; Microsporogenesis ; female gametophyte ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Development of pollen and female gametophyte inEpipogium roseum (D. Don)Lindl. has been investigated. The embryo sac conforms to the Apinagia type. The taxonomic position ofEpipogium within the family is discussed.
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    Fruit dimorphism inPhaseolus sublobatus (Fabaceae) and its evolutionary significance (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 67-72 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Fabaceae ; Phaseolus sublobatus ; Geocarpy ; amphicarpy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations of the annualPhaseolus sublobatus from different ecogeographical zones are genetically differentiated. In twelve populations from the western ghats (Maharashtra range) chasmogamous flowers are arranged in peduncled capitate racemes borne in leaf axils of higher nodes. One population (Poona Race S4) has additional inflorescences, also with chasmogamous flowers, on the main axis between the cotyledonary node and the ground. When the pods of these flowers ripen, the inflorescence gradually coils and, eventually, gets bury the fruits in the soil. This phenomenon is not known in any other plant.—The seed-coat patterns as revealed by SEM, and germination behaviour of both aerial and subterranean seeds are similar, and both types of seeds lack dormancy.—Heavy seed predation selection pressure is probably the principal cause for the evolution of fruit dimorphism inP. sublobatus. The origin of geocarpy in relation to fruit dimorphism and seed predation is discussed.
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    Distributional patterns and an additional species of thePassiflora vitifolia complex: Amazonian species diversity due to edaphically differentiated communities (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 95-105 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Passifloraceae ; Passiflora involucrata ; stat. et comb. nov. ; Species β-diversity ; Flora of Amazonia ; Peru
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field studies in Amazonian Peru show that thePassiflora vitifolia complex, a microcosm of many larger taxa, is concentrated in Amazonia with 4 ecologically separated species. One species is restricted to seasonally inundated forests, a second to non-inundated white sand soils, a third to non-inundated lateritic soils, and the fourth mostly to non-inundated alluvial soils. A new combination is formally proposed to recognize the white sand taxon, previously regarded as a variety, as a distinct species:P. involucrata. The importance of β-diversity in maintaining high Amazonian species diversity is emphasized.
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    The flower biology ofCephalanthera longifolia (Orchidaceae)—pollen imitation and facultative floral mimicry (1981)
    Springer
    Plant systematics and evolution 137 (1981), S. 229-240 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Cephalanthera longifolia ; Cistaceae ; Cistus salviifolius ; Hymenoptera ; Halictus ; Flower biology and ecology ; pollination ; pollen imitation ; floral mimicry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Solitary bees (Halictus sp.) were found to be the effective pollinators ofCephalanthera longifolia. In the same foraging flight the bees also visit flowers ofCistus salviifolius which has a similar colour pattern.Cephalanthera offers no reward to its pollinators, but orange papillae on its labellum successfully imitate pollen ofCistus. AsCephalanthera also attracts pollinators in the absence ofCistus, this is regarded as “facultative floral mimicry”.
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    Investigations on the content of steroidal alkaloids and sapogenins withinSolanum sect.Solanum ( = sect.Morella) (Solanaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 61-71 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Solanaceae ; Solanum sect.Solanum ; Diosgenin ; tigogenin ; solasodine ; chemosystematics ; ontogenetic shift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant material of 55 strains from 32 species ofSolanum sect.Solanum ( = sect.Morella) has been investigated for the content of steroidal alkaloids and sapogenins. The leaf-extracts of all species contain diosgenin resp. tigogenin or both together in considerable amount. On the contrary the characteristic steroidal alkaloid solasodine was absent in these samples. For 29 species the presence of steroidal sapogenins has been proved for the first time. In unripe fruits, however, solasodine could be detected in most of the species examined. New occurences of solasodine are reported for seven further species. These chemical results may contribute to a better comprehension of the difficult genusSolanum.—Ontogenetic studies on different organs ofS. atriplicifolium show the relationship between accumulation of steroidal compounds and plant maturity.
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    Tillandsia carminea — eine interessante neue Bromeliacee aus dem Orgelgebirge bei Rio de Janeiro (Brasilien) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 293-295 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Bromeliaceae ; Tillandsia subgen.Anoplophytum ; T. carminea ; spec. nova ; Flora of Brazil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tillandsia carminea is a new, morphologically and ecologically distinct species, related toT. stricta Solander, which occurs in the Serra dos Orgaos near Teresopolis, Brazil. It has been taken forT. rosea Lindley, but new investigations have shown thatT. rosea is a synonym toT. stricta and thatT. carminea is a good and distinct species.
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    The study of phosphorus and nitrogen fluxes in enriched isolation columns (1981)
    Springer
    Hydrobiologia 77 (1981), S. 49-60 
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    ISSN: 1573-5117
    Keywords: Phosphorus ; sediments ; isolation columns ; nutrient enrichment ; enclosures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolation columns positioned in approximately 3.5 m of water in Midmar Dam, were enriched with PO4-P and NO3-N, singly and in combination. Increased chlorophyll concentration resulted from all enrichment treatments. Responses showed marked seasonality and varied in intensity and duration. Despite the PO4-P fixing potential of the sediments, SRP concentrations increased markedly at times and possible reasons for this discussed. The marked response to addition of NO3-N alone suggested a flux of phosphorus from the sediment through the water to the algal component. The significance of periphyton within the columns is discussed.
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    Experimental measurement of sediment nitrification and denitrification in Hamilton Harbour, Canada (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 207-216 
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    ISSN: 1573-5117
    Keywords: sediments ; water column ; nitrification ; denitrification ; experiments ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This research examines the role of sediment nitrification and denitrification in the nitrogen cycle of Hamilton Harbour. The Harbour is subject to large ammonia and carbon loadings from a waste-water treatment plant and from steel industries. Spring ammonia concentrations rapidly decrease from 4.5 to 0.5 mg 1−1, while spring nitrate concentrations increase from 1 to 2 mg l−1, by mid-summer. A three-layer sediment model was developed. The first layer is aerobic; in it, oxidation of organics and nitrification occurs. The second layer is for denitrification, and the third layer is for anaerobic processes. Ammonia sources for nitrification include diffusion from the water column, sources associated with the oxidation of organics, sources from denitrification and from anaerobic processes. Diffusion of oxygen, ammonia and nitrate across the sediment-water interface occurs. Temperature effects are modelled using the Arrhenius concept. A combination of zero-order kinetics for nitrate or ammonia consumption with diffusion results in a half-order reaction, with respect to the water column loss rate to sediments. From experimental measurement, the rate of nitrification is 200 mg N 1−1 sediment per day, while that of denitrification is 85 mg N 1–1 sediment per day at 20 °C. The Arrhenius activation energy is estimated as 15 000 cal/ mole-K and 17 000 cal/ mole-K for nitrification and denitrification, respectively, between 10 °C and 20 °C. Calculations of the flux of ammonia with the sediments, using the biofilm model, compare favourably with experimental observations. The ammonia flux from the water column is estimated to account for 20% of the observed decrease in water column stocks of ammonia, while the nitrate flux from the water column is estimated to account for 25% of the total nitrogen produced by the sediments.
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    Particle size distribution and chemical parameters of the sediments of a shallow turbid impoundment (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 341-353 
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    ISSN: 1573-5117
    Keywords: Impoundment ; sediments ; particle size ; major ions ; nutrients ; cation exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As part of an ecosystem study of a small mesotrophic turbid impoundment in the semi-arid part of South Africa, an investigation was made of the particle size distribution, organic content and inorganic chemical composition of the sediment. Nine transects 50 m apart were made during February 1980. Sediments were sampled with an Eckman grab. The following analyses were made: size fractionation by wet sieving, cation exchange capacity, exchangeable Na, K, Ca, Mg and PO4, total P, and loss on ignition. From the results it was clear that the finer particles, in or near the original river bed, had higher cation exchange capacity, total P, exchangeable phosphorus and organic content. Littoral areas with avian habitat and extensive macrophyte vegetation, contained coarser sediments. Organic detritus apparently migrated to the deeper part of the impoundment. Sediments of lacustrine and fluvial origin were identified by means of the Passega classification.
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    Spatial heterogeneity in whole lake sediments — towards a loading estimate (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 235-240 
    Details
    ISSN: 1573-5117
    Keywords: sediments ; nutrients ; loading estimates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies of nutrient loadings, to shallow culturally eutrophied Alberta lakes, suggest internal inputs are significant. In this regard, estimation of bottom sediment P loads to Lake Wabamun (80 km2, 5.5 m $$\bar x$$ depth) were examined. Initially we determined the spatial variability in Total Organic Content (% loss on ignition) and Total Phosphorus, as indicators. Phosphorus fractions and biologically available phosphorus (BAP) were measured at specific stations. These data showed a very uniform distribution in sediment type with a Total Organic Content of 40.6 ± 3.3 (95% C.L.) at the west end, gradually declining to 26.3 ± 0.9 at the east end. Transects performed at routine monitoring stations indicate the representativeness of each station, e.g., station 2, 40.8 ± 1.3 (10 sites). One explanation of this uniformity is provided from210Pb analysis of shallow cores which indicate mixing to a depth of 16 cm. This is also thought to explain the mechanics of P loading to the water phase. Finally, Total Organic Content relates well to BAP (r2 = 0.80). It is hoped that this simple technique may well permit more precise extrapolation to whole lake BAP estimates at least on this lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00940114
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  • 98
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    Distribution and concentrations of naturally-occurring radionuclides in sediments in a uranium mining area of northern Saskatchewan, Canada (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 355-361 
    Details
    ISSN: 1573-5117
    Keywords: sediments ; uranium ; radium ; radionuclides ; models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Uranium mining and milling operations can contribute to environmental degradation through the increased release of naturally-occurring radionuclides. However, studies of the interactions of these radionuclides with freshwater sediments have been limited. The present study examined the vertical distribution of uranium, thorium, radium-226, polonium-210 and lead-210 in undisturbed sediment cores collected in the vicinity of mining, milling and exploration activities. Uranium levels in surface sediments ranged from 1.9 to 5650 µg g−1, Ra-226 from 〈0.1 to 480 pCi g−1 and Pb-210 from 0.8 to 931 pCi g−1 in the samples reported here, with the highest values occurring downstream of waste rock disposal areas. Concentrations usually decreased with depth, and there was little evidence of any strong effect of bioturbation on radionuclide profiles at the scale examined here. Mathematical models of uranium and radium-226 adsorption on and movement into the sediment were constructed, based on expected adsorption coefficients and estimated loading. The model predictions of radionuclide distribution with depth were qualitatively similar to those actually measured, but the predicted concentrations were generally lower than those observed, both in unaffected areas and in areas adjacent to uranium extraction activities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00000035
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  • 99
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    Lake sediments as recorders of geomagnetic field variations — applications to dating post-Glacial sediments (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 587-596 
    Details
    ISSN: 1573-5117
    Keywords: dating ; sediments ; geomagnetic variations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Field and laboratory methods, developed to recover the record of past secular variations of geomagnetic declination and inclination carried by the remanent magnetization of some lake sediments, are described. Type curves, delineating these parameters through post-Glacial time, have now been constructed for Europe and east-central N. America. These curves, once established for any region, are useful for dating lake sediments from that region. The principal inclination features exhibited by the European curves can also be identified along the N. American curves with a delay of some 600 years, on average.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02391973
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  • 100
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    Stratigraphic and dynamic effects of sediment reworking by Great Lakes zoobenthos (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 611-622 
    Details
    ISSN: 1573-5117
    Keywords: zoobenthos ; Great Lakes ; sediments ; radionuclides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent sediments of the North American Great Lakes are inhabited by numerous species of macrobenthos which alter the physical and chemical properties of sediments and modify interface transport characteristics. Distributions of such radionuclides as cesium-137, lead-210, and isotopes of plutonium exhibit a zone of constant activity extending down from the sediment-water interface from 1 to 15 cm. Recent studies have confirmed that radiometrically determined mixed depths are consistent with the vertical distribution of oligochaete worms and the amphipod,Pontoporeia hoyi. Generally, 90% of the benthos are contained within the radiometrically defined mixed zone. Where comparisons are possible, rates of sediment reworking by ‘conveyor belt’ species are comparable to or exceed sedimentation rates. Systematic variations in the mixed depth occur within depositional basins with greatest depths tending to be associated with least consolidated, organically rich materials. A quantitative steady-state mixing model accounts satisfactorily for observed radioactivity and heavy metal profiles. Bioturbation appears to be an important process, limiting the resolution with which historical records of particle-associated contaminants may be reconstructed from sediment cores. As bioturbation serves to maintain contact of contaminated sediments with overlying water, this time may also characterize the long-term lake recovery for contaminants removed by burial. As the time varies with location, a mean for an entire lake is not well known, but is on the order of 20 years for Lake Huron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02391976
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