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  • 42.80  (49)
  • sediments  (49)
  • Drosophila  (46)
  • Springer  (144)
  • American Chemical Society
  • Annual Reviews
  • Blackwell Publishing Ltd
  • 2005-2009
  • 1990-1994
  • 1980-1984  (144)
  • 1983  (46)
  • 1982  (98)
Collection
Keywords
Publisher
  • Springer  (144)
  • American Chemical Society
  • Annual Reviews
  • Blackwell Publishing Ltd
  • Wiley-Blackwell  (16)
Years
  • 2005-2009
  • 1990-1994
  • 1980-1984  (144)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Novel spectroscopy (1982)
    Springer
    Applied physics 28 (1982), S. 297-305 
    Details
    ISSN: 1432-0649
    Keywords: 32 ; 42.80 ; 33 ; 82 ; 34
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697859
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  • 2
    Electronic Resource
    Electronic Resource
    Origin of laser-output noise of cataphoretic HeSe+ lasers (1982)
    Springer
    Applied physics 28 (1982), S. 373-381 
    Details
    ISSN: 1432-0649
    Keywords: 42.55 ; 42.80 ; 52
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigated noise and fluctuations of the output power of cataphoretic HeSe+ lasers in positive column plasma. Direct coupling of laser output power noise and fluctuations of the local population inversion was found. An investigation of the positive column plasma showed moving striations being responsible for the gain fluctuations. Whereas the local plasma properties are dominated by high frequency striations in the 100 kHz range, integrated quantities such as laser gain per pass are most strongly influenced by low-frequency waves with a continuous noise spectrum below 200 kHz. External modulation of the discharge voltage or current at a frequency near thehf striations reduces laser noise and increases laser output power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686369
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  • 3
    Electronic Resource
    Electronic Resource
    Bragg diffraction of gaussian beams by thick gratings: Numerical evaluations by plane-wave decomposition (1982)
    Springer
    Applied physics 28 (1982), S. 383-390 
    Details
    ISSN: 1432-0649
    Keywords: 42.10 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The validity of 2-D coupled-wave theory is investigated for the case of Bragg diffraction of a Gaussian beam by a thick unslanted phase grating in transmission mode. Fourier plane wave decomposition theory, as presented in a companion article, is used to test 2-D coupled-wave theory under circumstances when its validity is in question, namely when the incident distribution is very narrow or fast-varying, or when the parameterv o, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large. Numerical evaluations of the field patterns at output from the grating, obtained using plane-wave decomposition, are used to explore the effect of the gradual violation of the conditions (from the previous article) under which 2-D coupled-wave theory is valid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686370
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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Theory of synchronously pumped dye lasers (1983)
    Springer
    Applied physics 30 (1983), S. 135-142 
    Details
    ISSN: 1432-0649
    Keywords: 42.55 ; 42.60 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An analysis of cw synchronously pumped dye lasers is presented. Under the assumption that the cavity (tuning element) bandwidth is much wider than the bandwidth of the transform limited pulses generated, the pulse forming dynamics is rigorously treated. It is shown that for a finite mismatch between the lengths of the dye and the pump lasers, a steady-state pulse develops in the dye laser cavity with a conserved pulseshape. The characteristics (energy, shape, peak power, duration) of these pulses of ultimate width are quantitatively determined as a function of cavity mismatch. An analytical solution for the pulse envelope is determined, which yieldsI(t)∝Sech2(t/t p ) to a good approximation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695468
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  • 6
    Electronic Resource
    Electronic Resource
    Color signal correlation detection by matched spatial filtering (1983)
    Springer
    Applied physics 32 (1983), S. 1-6 
    Details
    ISSN: 1432-0649
    Keywords: 42.30 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A polychromatic correlation detection technique by complex spatial filtering is presented. This technique utilizes a diffraction grating and three co-lineared (red, green, and blue) coherent sources. The technique of complex spatial filter synthesis for the polychromatic corelation detection is demonstrated. This technique offers true color correlation detection which is very suitable for color signal recognition and identification. The correlation diffraction efficiency with this technique is generally higher than that of the wavelength-multiplexed technique. Several interesting experimental demonstrations of this color signal correlation detection scheme are provided. Finally we note that this color signal detection technique is a simple and versatile processing technique which has broad range of applications of complex color signal detection, recognition and identification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688766
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  • 7
    Electronic Resource
    Electronic Resource
    Waveform of the amplitude modulated laser light by means of a mechanical chopper (1983)
    Springer
    Applied physics 32 (1983), S. 119-122 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The model which reproduces accurately and conveniently the waveform of the amplitude modulated cw laser light in the TEM00 mode by a mechanical chopper is developed. It is found that its predictions are in good agreement with the strict, completely accurate but rather lengthy and inconvenient treatment and with the experiment. The criterion for the efficient amplitude modulation of the laser light by a mechanical chopper is formulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688816
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  • 8
    Electronic Resource
    Electronic Resource
    Bistable operation of a dual-wavelength synchronously mode-locked cw dye laser (1983)
    Springer
    Applied physics 32 (1983), S. 7-8 
    Details
    ISSN: 1432-0649
    Keywords: 42.60 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Bistable operation of a dual-wavelength synchronously mode-locked cw dye laser is reported. Wavelength switching is found to depend on the pump power and the dye laser cavity lengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688767
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  • 9
    Electronic Resource
    Electronic Resource
    Differential amplitude contrast imaging in the scanning optical microscope (1983)
    Springer
    Applied physics 32 (1983), S. 187-191 
    Details
    ISSN: 1432-0649
    Keywords: 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A split detector is used in a scanning optical microscope to produce high-quality differential amplitude contrast images. A slight lateral offset in the detector position is shown to introduce information about object height variations to the image. These results are compared with images obtained by electrical differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688286
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  • 10
    Electronic Resource
    Electronic Resource
    Coherence requirement for partially coherent correlation detection (1983)
    Springer
    Applied physics 30 (1983), S. 23-27 
    Details
    ISSN: 1432-0649
    Keywords: 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The coherence requirement for correlation detection is determined using the theory of partially coherent light. It is shown that the requirement for temporal coherence strongly dependes on the spatial frequency and the spatial extension of the target (i.e., space bandwidth product). However, the spatial coherence requirement depends only on the extension of the target. Some numerical results are also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692654
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  • 11
    Electronic Resource
    Electronic Resource
    Guided waves and IR lasers (1982)
    Springer
    Applied physics 28 (1982), S. 283-289 
    Details
    ISSN: 1432-0649
    Keywords: 85.60 ; 42.80 ; 42.55 ; 33
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697857
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  • 12
    Electronic Resource
    Electronic Resource
    Light-polarization modifications in a multipass cavity (1982)
    Springer
    Applied physics 29 (1982), S. 43-54 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 32
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper analyses the slight change undergone by the polarization of a laser beam performing a multipass between two spherical mirrors facing each other. We replace the general 16-parameter Mueller formalism by an approximate 7-parameter one, and we give a quantitative experimental criterion for the validity of this approximation. Then we apply this formalism to the analysis of our experimental data. The results evidence:i) intrinsic birefringence in the mirror coatings (typical value per reflexion ∼2 to 4×10−4 rad);ii) birefringence due to off-normal incidence (typically 3.6×10−5 rad per reflexion for an incidence of 2×10−2 rad);iii) optical rotation, of purely geometrical origin (typically 14° for a multipass with revolution symmetry and 100 forward-backward passes under constant incidencei=2°);iv) no observable circular dichroism (≲10−6). Finally these results are discussed in connection with possible associated systematics in a parity violation experiment which motivated this work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694368
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  • 13
    Electronic Resource
    Electronic Resource
    Coherent transient phenomena (1982)
    Springer
    Applied physics 29 (1982), S. 179-182 
    Details
    ISSN: 1432-0649
    Keywords: 33 ; 34 ; 36 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688662
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  • 14
    Electronic Resource
    Electronic Resource
    Resonant upconversion of λ=1.06 μm radiation in rubidium vapors (1983)
    Springer
    Applied physics 30 (1983), S. 157-159 
    Details
    ISSN: 1432-0649
    Keywords: 42.65 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The experimental results on upconversion of λ=1.06 μm radiation to the near ultraviolet in rubidium vapors providing 12% photon efficiency are reported under twophoton resonance of the concerted and pump sum frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695472
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  • 15
    Electronic Resource
    Electronic Resource
    Ambartsumian's principle of invariance and the reflection of radio waves from plane inhomogeneous slabs (1983)
    Springer
    Applied physics 30 (1983), S. 183-188 
    Details
    ISSN: 1432-0649
    Keywords: 41 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using Ambartsumian's principle of invariance we investigate for radio waves the reflection coefficient of a plane inhomogeneous slab. We find that the reflection coefficient, as a function of slab thickness, satisfies the Riccati equation. From this equation we deduce a geometric theorem on the upper and lower bounds of the reflection coefficient. We illustrate the theorem by applying it to several special cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688404
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  • 16
    Electronic Resource
    Electronic Resource
    Sub-Doppler excited molecule energy transfer spectroscopy (1982)
    Springer
    Applied physics 27 (1982), S. 153-156 
    Details
    ISSN: 1432-0649
    Keywords: 33 ; 42.80 ; 07.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A sub-Doppler spectroscopic technique involving the detection of vibrational energy transfer in excited molecules with selected velocity components at a microphone diaphragm is demonstrated. The technique is applied to the investigation of thev 3 R(16) transition in HCN and the results compared with a previously derived theoretical model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694641
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  • 17
    Electronic Resource
    Electronic Resource
    F-center-laser. Superconductivity (1982)
    Springer
    Applied physics 28 (1982), S. 306-310 
    Details
    ISSN: 1432-0649
    Keywords: 68 ; 42.70 ; 42.60 ; 61.70 ; 61.50 ; 42.80 ; 29
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697860
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  • 18
    Electronic Resource
    Electronic Resource
    Formation of blazed holographic gratings (1982)
    Springer
    Applied physics 28 (1982), S. 349-353 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.82
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Various methods for the recording of blazed holographic diffraction gratings are presented and the regions in the wavelength-groove density plane for which they can be used are shown. The gratings are made in the positive photoresist Shipley AZ-1350. The diffraction efficiency for s and p polarization was measured as a function of wavelength and angle of incidence. An absolute efficiency of 80% was achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686365
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  • 19
    Electronic Resource
    Electronic Resource
    Apparent transfer function for partially coherent optical information processing (1982)
    Springer
    Applied physics 28 (1982), S. 359-366 
    Details
    ISSN: 1432-0649
    Keywords: 42.30 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper, the general formulations of the apparent transfer function for the partially coherent optical processor will be derived. Although these formulas show that the apparent transfer function is dependent upon the degree of spatial and temporal coherence, there is actually more variability in the spatial coherence. We note that the obtained formulas may also be used as a criterion in the selection of source size and spectral bandwidth of an incoherent light source. Thus a specific optical information processing operation can be carried out with an incoherent source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686367
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  • 20
    Electronic Resource
    Electronic Resource
    Development of an optical time scale (1982)
    Springer
    Applied physics 29 (1982), S. 63-65 
    Details
    ISSN: 1432-0649
    Keywords: 42.60 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A time standard based on the use of an optical oscillation period of a frequencystable He−Ne laser as a time scale is first described. We obtained highly frequency-stable oscillations in the SHF range that were locked to the oscillations of a He−Ne laser stabilized to an absorption resonance in methane at 3.39 μm. A direct comparison of frequency stabilities of a rubidium standard and He−Ne/CH4 laser has been made. The absolute measurement of the frequency of the He−Ne/CH4 laser we performed gave a new value of frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694370
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  • 21
    Electronic Resource
    Electronic Resource
    Energy transfer processes in two different bifluorophoric laser dyes (1982)
    Springer
    Applied physics 29 (1982), S. 73-77 
    Details
    ISSN: 1432-0649
    Keywords: 82 ; 78.60 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The mechanism of intramolecular energy transfer in two bifluorophoric laser dyes has been investigated by measurements of laser parameters, excited state absorption and phosphorescence spectra. The new value found for the dimethyl-POPOP triplet energy (48.0 kcal/mole) accounts for the different behaviour of the two classes of bifluorophoric dyes used in this investigation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692766
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  • 22
    Electronic Resource
    Electronic Resource
    Novel quantum-electronics phenomena and devices (1982)
    Springer
    Applied physics 29 (1982), S. 152-156 
    Details
    ISSN: 1432-0649
    Keywords: 42.80 ; 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688656
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  • 23
    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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  • 24
    Electronic Resource
    Electronic Resource
    Ethylene monitoring by differential absorption with a CO2 waveguide laser (1982)
    Springer
    Applied physics 29 (1982), S. 227-233 
    Details
    ISSN: 1432-0649
    Keywords: 86 ; 70L ; 07.60 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper we report on a differential absorption technique using a CO2 waveguide laser. The method is based on the measurement of the differential absorption between two different frequencies of the same selected CO2 laser line. The sensitivity of the technique depends strongly on the total pressure and has been estimated to be about a few tens of ppb or better over a 1 km path length in C2H4 diluted with air to a total pressure of a few tens of torrs. Its relative simplicity and high sensitivity at low total pressure enable this technique to be applied to gas detection either at high altitude or to local monitoring of a low pressure sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688673
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  • 25
    Electronic Resource
    Electronic Resource
    Harmonic detection with tunable diode lasers —two-tone modulation (1982)
    Springer
    Applied physics 29 (1982), S. 279-285 
    Details
    ISSN: 1432-0649
    Keywords: 07.65 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The minimum absorption detectable by a tunable diode laser spectrometer utilising harmonic techniques is often limited by interference fringes generated by scattered light. The sensitivity of the spectrometer to absorption can be increased by applying a jitter modulation. In this paper, the theory of harmonic response for single- and two-tone modulation over optical fringes and Lorentzian absorption lines is developed and compared to experimental measurements. A simple analytic expression for the two-tone harmonic line shape is derived. This expression provides a physical understanding of the effects of the second modulation, and a means to unravel the effects of the second modulation on the linewidth and line shape. For a specific choice of the jitter frequency and phase, it is possible to simultaneously minimise the fringe signal and increase the harmonic absorption signal. The results of this investigation are applicable to trace gas detection using tunable diode lasers, and to other areas of spectroscopy and magnetic resonance where harmonic techniques are used.
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    URL: http://dx.doi.org/10.1007/BF00689188
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  • 26
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    Complete and reversible absorption of radiation (1983)
    Springer
    Applied physics 32 (1983), S. 153-156 
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    ISSN: 1432-0649
    Keywords: 44.40 ; 05.70 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Kirchhoff's law has caused confusion in the discussion about the theoretical maximum work from radiation because it permits only infinitesimal or irreversible absorption. With the aid of an optical circulator, non-Kirchhoff behaviour is possible in principle which permits at the same time complete and reversible radiation absorption. The key to overcome Kirchhoff's law seems to be the magnetic field, a condition explicitly excluded by Kirchhoff. The work extracted in complete reversible conversion of radiation is calculated. The irreversibilities connected with the emission process are discussed.
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    URL: http://dx.doi.org/10.1007/BF00688821
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  • 27
    Electronic Resource
    Electronic Resource
    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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  • 28
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    The analysis of excite and probe measurements of relaxation times with fluctuating pulse duration (1982)
    Springer
    Applied physics 29 (1982), S. 135-138 
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    ISSN: 1432-0649
    Keywords: 06 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of fluctuations in the pulse duration of synchronously pumped modelocked pulse trains on excite and probe measurements is discussed. Relaxation times comparable with the pulse durations can be measured even when large pulse-to-pulse fluctuations in duration exist. The pump and probe pulse durations are assumed to be correlated. When the probe pulses are the second harmonic of the pump, or vice versa, the third harmonic must also be generated to permit deconvolution of experimental excite and probe data. When the pump and probe pulses have the same time dependence, the excite and probe curves consist of the desired response function convolved with the time-averaged second harmonic autocorrelation function which is easily measured. Deconvolution yields the relaxation time but fluctuations in pulse duration increase the root-mean-square voltage fluctuation at the output of the detector system and limit the accuracy with which the relaxation time can be calculated.
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    URL: http://dx.doi.org/10.1007/BF00692776
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  • 29
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    Surface spectroscopy (1982)
    Springer
    Applied physics 29 (1982), S. 182-185 
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    ISSN: 1432-0649
    Keywords: 36 ; 42.80 ; 52
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688663
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  • 30
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    Effective upconversion of CO2-laser radiation in sodium vapors (1983)
    Springer
    Applied physics 30 (1983), S. 53-55 
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    ISSN: 1432-0649
    Keywords: 42.65 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effective upconversion of CO2-laser radiation to the uv spectral range has been obtained in sodium vapors, the photon efficiency being 65%, the corresponding power efficiency being 2640%.
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    URL: http://dx.doi.org/10.1007/BF00692659
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  • 31
    Electronic Resource
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    Diffraction efficiencies of evanescent-wave holograms (1983)
    Springer
    Applied physics 30 (1983), S. 87-94 
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    ISSN: 1432-0649
    Keywords: 42.40 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In contrast to previous models diffraction efficiencies of evanescent-wave holograms are calculated within the framework of a slab model that takes into account the finite thickness of the recording medium. This modification leads to characteristic diffraction efficiency oscillations with respect to reconstruction angle and medium thickness as well. One obtains higher diffraction efficiency maxima and pseudo-optical tunnelling. The analysis covers TE-polarized fields.
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    URL: http://dx.doi.org/10.1007/BF00688482
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  • 32
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    Three-dimensional surface measurement using the confocal scanning microscope (1982)
    Springer
    Applied physics 27 (1982), S. 211-213 
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    ISSN: 1432-0649
    Keywords: 06 ; 42.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The use of the depth discriminination property of the confocal scanning microscope for surface profiling has been adapted to provide a method of high-resolution three-dimensional surface profilometry. Measurements on a semiconductor specimen demonstrate the technique; depth variations of the order of 0.1 μm are clearly resolved.
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    URL: http://dx.doi.org/10.1007/BF00697444
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    On the relation between genetic and environmental variability in animals (1982)
    Springer
    Journal of molecular evolution 18 (1982), S. 310-314 
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    ISSN: 1432-1432
    Keywords: Neutral mutation theory ; Natural selection ; Protein evolution ; Levene model ; Environmental variability ; Genetic variability ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary If a phenotypic character is under stabilizing selection, the selective disadvantage of a nonoptimal genotype will decrease exponentially to zero as the proportion of phenotypic variation that is environmental in origin -V e /V p - increases. Under the modified mutation-drift hypothesis of genetic polymorphism, the proportion of mutations that are effectively neutral and average heterozygosity should increase with this ratio. Invertebrates, because of their small size, fast development, and low degree of homeostasis (relative to vertebrates), are expected to show a larger environmental component of phenotypic variation than vertebrates. This may help explain why invertebrates are in general more genetically variable than vertebrates and why, when laboratory populations ofDrosophila are maintained in heterogeneous environments, genetic variability is lost less rapidly than when they are kept in constant conditions.
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    Source encoding for partially coherent optical processing (1982)
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    Applied physics 27 (1982), S. 99-104 
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    ISSN: 1432-0649
    Keywords: 42.30 ; 42.80
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    Topics: Physics
    Notes: Abstract A relation between spatial coherence function and source encoding intensity transmittance function is presented. Since the spatial coherence is depending upon the information processing operation, a strictly broad spatial coherence function may not be required for the processing. The advantage of the source encoding is to relax the constraints of strict coherence requirement, so that the processing operation can be carried out with an extended incoherent source. Emphasis of the source encodings and experimental demonstrations are given. The constraint of temperal coherence requirement is also discussed.
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    Bragg diffraction of finite beams by thick gratings: Two rival theories (1982)
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    Applied physics 28 (1982), S. 63-72 
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    ISSN: 1432-0649
    Keywords: 42.10 ; 42.80
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    Topics: Physics
    Notes: Abstract Two rival techniques used in the analysis of Bragg diffraction of two-dimensional light beams by thick unslanted phase gratings, namely Fourier plane wave decomposition and 2-D coupled-wave theory, are compared. The advantages and regions of applicability of each are discussed, and the conditions found under which they yield identical results. In particular, the results of plane-wave decomposition are used to provide quantitative conditions for validity of 2-D coupled-wave theory. These conditions are not easily derived using any other technique, and set quantitative limits to how narrow or fast-varying the incident distribution may be before 2-D coupled-wave theory fails. It is also shown that 2-D coupled-wave theory is inadequate when the parameterv 0, due to Kogelnik (1969), which is proportional to the product of coupling rate and grating thickness, is very large.
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    Applications of ps-pulses (1982)
    Springer
    Applied physics 28 (1982), S. 246-254 
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    ISSN: 1432-0649
    Keywords: 42.80 ; 42.65 ; 34 ; 42.55 ; 42.70 ; 78
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    Topics: Physics
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    Theory II (1982)
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    Applied physics 28 (1982), S. 255-261 
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    ISSN: 1432-0649
    Keywords: 42.55 ; 36.20 ; 36.10 ; 02 ; 36 ; 42.80
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    Topics: Physics
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    URL: http://dx.doi.org/10.1007/BF00697853
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    Coherent transient phenomena (1982)
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    Applied physics 28 (1982), S. 274-282 
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    ISSN: 1432-0649
    Keywords: 42.80 ; 33 ; 36 ; 36.10 ; 14 ; 32
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697856
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    Modulation of radiation in nonstationary resonant media (1983)
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    Applied physics 30 (1983), S. 41-45 
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    ISSN: 1432-0649
    Keywords: 42.80 ; 42.10 ; 42.55
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    Topics: Physics
    Notes: Abstract We study the propagation of radiation in a gas, the resonant frequency of which changes with time when affected by external electric and magnetic fields. It is shown that for an harmonic change of the resonant frequency under appreciable energy exchange between electromagnetic field and medium, deep amplitude modulation of radiation may be achieved. The analytical expressions obtained for a field in a gas allow rather accurate calculation of the space-time structure of the radiation penetrated through the medium layer. The numerical calculations are compared with the known experiment [4], good agreement is obtained. The transformation of radiation between dispersive branches with adiabatic stepwise variation of the resonant frequency has been also studied. Branch-tobranch transformation is investigated and the adiabatic invariant is found to be the total number of the high and low frequency radiation quanta corresponding to two dispersive branches.
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    New lasers II (1982)
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    Applied physics 28 (1982), S. 233-239 
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    ISSN: 1432-0649
    Keywords: 42.70 ; 42.55 ; 42.80
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    Topics: Physics
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    URL: http://dx.doi.org/10.1007/BF00697850
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    Laser fusion (1982)
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    Applied physics 28 (1982), S. 269-273 
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    ISSN: 1432-0649
    Keywords: 52 ; 42.55 ; 42.80 ; 51
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    Topics: Physics
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    The dielectric constant of PbTe at 4.2 K and $$\tilde v$$ =84.15 cm-1, 96.97cm−1, 103.60cm−1 (1982)
    Springer
    Applied physics 28 (1982), S. 229-233 
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    ISSN: 1432-0630
    Keywords: 77 ; 42.80
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The dielectric constant of a PbTe epitaxial layer has been measured by surface wave spectroscopy using an optically pumped far-infrared laser and the technique of attenuated total reflection.
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    Effects of a magnetic field on the optical properties of dielectric mirrors (1983)
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    Applied physics 32 (1983), S. 63-67 
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    ISSN: 1432-0630
    Keywords: 42.80 ; 78.20 ; 78.65
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have measured the changes in the polarization state of a monochromatic (λ=514.5 nm) light beam on reflection at normal incidence by a multilayer dielectric mirror placed in a time-modulated magnetic field. The dominant effect is a Faraday rotationΦ≃3.7×10−10 rad/G. The sensitivity (around 40Hz) obtained is $$ \simeq 6 \times 10^{ - 9} {\text{ rad/}}\sqrt {{\text{Hz}}} $$ which is dominated by the shot-noise limit (100 mW of light power).
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    Refractive index profiles of LiNbO3: Ti waveguides (1983)
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    Applied physics 32 (1983), S. 125-127 
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    ISSN: 1432-0630
    Keywords: 42.80 ; 66.30 ; 85.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Eight LiNbO3: Ti waveguides have been fabricated under differing conditions. The effective refractive indices of guided modes have been measured and successfully fitted to Gaussian index profiles. The change of refractive index and titanium concentration are related by a power law, the exponents being different for the extraordinary and the ordinary beam.
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    Photoconducting tellurium for submillimeterwave detectors (1982)
    Springer
    Applied physics 27 (1982), S. 35-38 
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    ISSN: 1432-0630
    Keywords: 42.80 ; 72.40 ; 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 Undoped tellurium single crystals show at low temperatures (2.2 K) strong photoeffect under submillimeter irradiation. Therefore, tellurium was used as a FIR-detector. For a comparison with other detectors signal-to-noise ratio, response time, and noise equivalent power were determined. Tests were carried out with HCN-laser radiation (λ = 337 μm,≈ν = 30 cm- t). The sensitivity of the Tc-photoconductor is comparable to that of a TGS-bolometer but lower than that of a Ge-bolometer. The Te-detector is much faster than the bolometers.
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    Optical properties determination at 10.6 μm of thin semiconducting layers (1983)
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    Applied physics 30 (1983), S. 23-26 
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    ISSN: 1432-0630
    Keywords: 07.60 ; 42.80
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract An optical characterization of thin semiconducting multilayers in the infrared range, using a combination ofm-lines and reflection spectroscopy techniques is exposed. Such a method, non-destructive, allows to determine the thickness and the refractive index of each component of a multilayer multimodal planar waveguide.
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    Measuring the Magnetooptic Kerr effect by diffraction (1983)
    Springer
    Applied physics 31 (1983), S. 59-63 
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    ISSN: 1432-0630
    Keywords: 78.20 L ; 42.80 ; 75.70
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A method is presented to measure the Magnetooptic Kerr Effect (MOKE) by diffraction. This is accomplished by giving the magnetized surface a magnetization distribution which functions like a linear diffraction grating. It is shown that the first and higher orders of the light diffracted by such a grating are produced by MOKE whereas the zero order approximately represents the reflectivity of the surface (given by the Fresnel formulae assuming zero magnetization). The procedure used here to form a grating is restricted to thin soft magnetic films, and has been demonstrated on evaporated Fe-Ni films. It uses the magnetic field of a pulse-driven meandered stripe-conductor placed in close contact with the film in the presence of a homogeneous external magnetic field. Experimentally determined Kerr intensities were compared with those measured by ellipsometric methods. Good agreement was found in the case of films with uniaxial anisotropy. For films with no anisotropy, the relative dependence of Kerr intensity vs wavelength, polarisation and angle of incidence could be derived.
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    Optical method for measuring the coupling constant of surface acoustic waves (1982)
    Springer
    Applied physics 27 (1982), S. 95-97 
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    ISSN: 1432-0630
    Keywords: 42.80 ; 62
    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 coupling constant of common or thin-layered-piezoelectric interdigital transducers for surface acoustic waves up to the highest frequencies can be determined in an optical way with reproducibility better than 3%. Being a nondestructive and noncontact method one can apply it in the technological process for fabricating uniform piezoelectric layered transducers.
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    Space-time resolved reflectivity measurements of picosecond laser-pulse induced phase transitions in (111) silicon surface layers (1982)
    Springer
    Applied physics 27 (1982), S. 153-160 
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    ISSN: 1432-0630
    Keywords: 78.20 ; 81 ; 42.80
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The changes in reflectivity of a silicon surface, irradiated by a green picosecond pulse, are probed during and following that pulse with a spatial resolution of 10 μm. The data indicate the development of a liquid phase, and a resolidification either into a single crystal or an amorphous phase. The latter has a characteristic ring-type pattern, and occurs only at locations where the incident picosecond laser fluence lies between 0.2 and 0.26 J/cm2. The reflectivity data appear to be in good quantitative agreement with a “simple heating” model, in which the electrons and phonons maintain a local thermodynamic equilibrium on a picosecond time scale.
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    Radiation sensitivity of thick core all-glass fibers in reactor radiation fields (1982)
    Springer
    Applied physics 28 (1982), S. 45-51 
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    ISSN: 1432-0630
    Keywords: 42.10 ; 42.80 ; 78.20
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Radiation induced losses and the recovery behavior of several optical fibers have been determined by in situ steady state and by pulse measurements in a nuclear reactor. Agreement with the literature was found for Suprasil and Fibropsil core fibers in ionizing radiation, but our results on Suprasil-W core fibers show an appreciably higher radiation hardness of this material than reported elsewhere. Additionally, increased long term losses were observed, when the mixed radiation flux contained a noticeable content of neutrons.
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    The role of the peripodial membrane in the morphogenesis of the eye-antennal disc ofDrosophila melanogaster (1983)
    Springer
    Development genes and evolution 192 (1983), S. 164-170 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The early morphogenesis of the eye-antennal disc ofDrosophila in response to 20-hydroxy ecdysone involves the curling of the eye anlagen dorsally over the antenna. During this process, the area of the peripodial membrane is substantially reduced. The peripodial membrane is taut at this stage, and if it is cut the curling of the disc cannot continue, and the eye anlagen returns to its original position within one minute of the operation. In contrast, cutting the columnar epithelium between the eye and antennal anlagen does not disrupt curling, but actually facilitates it. During curling, the cells of the peripodial membrane appear healthy, and exhibit basal extensions. We suggest that the curling of the eye is mediated by the conversion of cuboidal peripodial membrane cells into pseudostratified columnar epithelium at the edges of the peripodial membrane. Subsequently, cells of the peripodial membrane secrete first a pupal cuticle, and then an imaginal cuticle.
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    The evagination of the genital imaginal discs ofDrosophila melanogaster (1983)
    Springer
    Development genes and evolution 192 (1983), S. 275-279 
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    ISSN: 1432-041X
    Keywords: Evagination ; Morphogenesis ; Metamorphosis ; Female genital disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The morphology of the evaginating female genital disc ofDrosophila melanogaster was examined at different stages of metamorphosis. The observations show that the internal genital organs are derived from the anterior half of the disc and that their morphogenesis is mainly a protrusion of the different primordial areas of the disc epithelium. The external genital and anal derivatives originate from the posterior half of the disc, which undergoes complex rearrangements during metamorphosis. The disc opens along the posterior margin and the dorsal and ventral epithelia evert and thereby completely reverse their anteroposterior orientation. Dramatic elongation has been observed during the formation of the seminal receptacle. The cells of the repressed male genital primordium do not form any recognizable structures and are assumed to be eliminated during metamorphosis.
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    The effect of 5-azacytidine and cytidine analogs onDrosophila melanogaster cells in culture (1983)
    Springer
    Development genes and evolution 192 (1983), S. 299-302 
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    ISSN: 1432-041X
    Keywords: Differentiation ; Teratogens ; Drosophila ; 5-Azacytidine ; Methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of cytidine and cytidine analogs were studied inDrosophila embryonic cell cultures and two wild-type established cell lines, Oregon-R and Schneider line 2. Primary embryonic cultures have been shown to be an excellent system for the study of embryonic development; a number of cell types undergo normal differentiation in vitro. Treatment of these cultures with putative teratogens resulted in an inhibition of muscle and/or neuron differentiation in our study. Treatment of these cells with cytidine and seven other analogs had no effect on neuron and muscle differentiation. The compound 5-azacytidine, when added to primary cell cultures, inhibited normal differentiation at subtoxic doses while inducing the production of three proteins that comigrate with the heat-shock proteins, hsp 23, 22a and 22b. 5-Azacytidine did not stimulate differentiation in Oregon-R or SchneiderDrosophila cell lines. The in vitro blockage of differentiation by 5-azacytidine suggests that it may act as a teratogen.
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    Correlation between adult transformation and aldehyde oxidase staining pattern in wing discs ofApterous genotypes inDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 285-288 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal discs ; homoeosis ; Compartments ; Aldehyde oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The aldehyde oxidase staining pattern in wing discs ofDrosophila melanogaster bearing the genotypesap blt /ap blt andap blt andap blt /ap 73n showns changes from the wild-type pattern. Extensive areas of the presumptive dorsal posterior wing blade, which are normally unstained, have enzyme activity in these mutants. In wings of these genotypes, dorsal posterior structures are replaced by dorsal anterior wing structures. A strong correlation has been found between the frequencies of various staining patterns in the discs and the extent of transformation in the cuticular structures of the wing, which is consistent with the idea that aldehyde oxidase activity can be used as an indicator in the wing disc of this transformation. Unlike the homoeotic mutationengrailed, apterous has not been interpreted as a selector gene yet the work reported here shows thatapterous alleles can cause changes resembling those of theengrailed phenotype both in aldehyde oxidase staining behaviour and in the cuticular transformation.
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    Effects of the “sexcombless” chromosome (In(1)sx) on males and females ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 264-269 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Sexcombless ; Foreleg basitarsus ; Genital disc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The chromosome which carries the mutationsexcombless (In(1)sx) affects males and females ofD. melanogaster. In the male foreleg basitarsi the number of sexcomb teeth is dramatically reduced from 10 to 0.7 and the number of transverse rows of bristles is increased from 6 to 8. Females homozygous forIn(1)sx show a normal bristle pattern in the foreleg basitarsus. The genital disc derivatives of both male and femaleIn(1)sx flies are strongly affected. While the external genitalia show a duplicated or a reduced bristle pattern, the internal genitalia are mostly absent. However, the sexually dimorphic tergites and sternites of the abdomen remain unaffected. The male-specific effect on the basitarsus and the general effects on the genital disc derivatives are proposed to represent two different phenotypic effects ofIn(1)sx which may derive from mutations at different gene loci in the inverted chromosome.
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    Growth is required for cell competition in the imaginal discs ofDrosophila melanogaster (1982)
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    Development genes and evolution 191 (1982), S. 289-291 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal discs ; Cell competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Imaginal wing discs from late third-instar larvae were gammairradiated to induce clones of rapidly growingMinute − cells in a background of slowly growingMinute cells and culturedin vivo for periods up to 18 days. Clones in discs cultured for 16 to 18 days did not grow significantly larger than clones in uncultured controls, indicating that competition between populations of cells having potentially different mitotic rates does not occur in imaginal discs after their growth is completed.
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    The evagination of the genital imaginal discs ofDrosophila melanogaster (1983)
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    Development genes and evolution 192 (1983), S. 280-284 
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    ISSN: 1432-041X
    Keywords: Evagination ; Morphogenesis ; Metamorphosis ; Intersexual genital disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Morphogenetic movements of the intersexual genital disc of thedoublesex-dominant mutant ofDrosophila melanogaster were followed during metamorphosis. Intersexual genital discs contain well developed genital primordia of both sexes as well as an anal primordium, and all of these primordia evaginate simultaneously. The female genital primordium is deflected to the ventral side by the male genital primordium which is located anterior to it. Subsequently the anterior parts of the two genital primordia project their internal appendages in parallel in the anterior direction. The morphogenetic movements closely resemble those of the corresponding parts of normal males and females. The disc opens at the stalk along the posterior edge and the two genital primordia completely evert their posterior parts. These areas undergo complex rearrangements whereby the anlage for the male genital arch as well as that for the 8th tergite evert and move around the lateral side of the disc. They both fuse dorsally after enclosing the anal tube. The formation of the characteristic abnormalities of the intersexual genitalia seems not to result simply from spatial problems of the simultaneous evagination of the genital anlagen but rather to be a direct result of the ambiguous genetic signalling in the intersexual cells of these primordia.
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    Cell lineage restrictions in the genital disc ofDrosophila revealed byMinute gynandromorphs (1983)
    Springer
    Development genes and evolution 192 (1983), S. 337-346 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Gynandromorphs ; Genital disc ; Compartments ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genital imaginal disc ofDrosophila differentiates the terminalia, i.e. the genitalia and analia, of both sexes. It represents a composite anlage, containing a female genital primordium, a male genital primordium and an anal primordium. In normal males and females, only one of the two genital primordia differentiates; the other is developmentally repressed. Therefore, cell-lineage relationships between the male and female genital primordia can only be studied in sexual mosaics which differentiate female and male cells. We producedMinute (M)‖non-Minute(M+) gynandromorphs and selected those with sexually mosaic terminalia for a cell-lineage analysis. In these mosaics, either the male (XO) or female (XX) cells wereM + and thus had a growth advantage. The differential growth rates served as a tool to detect clonal restrictions. In control gynandromorphs (M +‖M +), the amount of female genitalia differentiated was largely independent of the amount of male genitalia present. In contrast, male and female anal structures, as a rule, added up to one full set. The same was true for the experimentalM‖M + gynandromorphs, but the contribution ofXX andXO cells to mosaic terminalia changed drastically due toM + cells competing successfully against the more slowly growingM cells. Specific subsamples ofM‖M + gynandromorphs showed thatM cells in a non-mosaic primordium are shielded from cell competition taking place in the neighbouring mosaic primordium. We conclude that the three primordia of the genital disc represent developmental compartments. In the genital primordia, even developmentally repressedM + cells compete successfully against developmentally activeM cells.
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    Sequential gene activation by ecdysteroids in polytene chromosomes ofDrosophila melanogaster (1982)
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    Development genes and evolution 191 (1982), S. 103-111 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Polytene Chromosomes ; Ecdysteroids ; Fat Body
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Changes in polytene chromosome 3 L puffing patterns in the fat body ofDrosophila melanogaster larvae and prepupae are compared to those in the salivary gland. While some general features are common to the two tissues, there are differences which reflect their different developmental roles. In vitro experiments with fat body chromosomes show that they have a distinct response to ecdysteroids which is different from that of salivary gland chromosomes, and which does not,in this culture system, reproduce the changes observed in normal development. In short term culture experiments, the fat body chromosomes appear more sensitive to ecdysteroids than the salivary gland chromosomes and, although 20-OH ecdysone is more active than ecdysone in these assays, the possibility is not excluded that ecdysone has a role in normal development as it appears to alter gene activity at physiological levels in these cells.
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    Homologies of positional information in thoracic imaginal discs ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 293-300 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal discs ; Positional information ; Homology ; Intercalary regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The regulative behavior of fragments of the imaginal discs of the wing and first leg was studied when these fragments were combined with fragments of other thoracic imaginal discs. A fragment of the wing disc which does not normally regenerate when cultured could be stimulated to regenerate by combination with certain fragments of the haltere disc. When combined with a haltere disc fragment thought to be homologous by the criteria of morphology and the pattern of homoeotic transformation, such stimulated intercalary regeneration was not observed. Combinations of first and second leg disc fragments showed that a lateral first leg fragment could be stimulated to regenerate medial structures when combined with a medial second leg disc fragment but not when combined with a lateral second leg disc fragment. Combinations of wing and second leg disc fragments showed that one fragment of the second leg disc is capable of stimulating regeneration from a wing disc fragment while another second leg disc fragment fails to stimulate such regeneration. It is suggested that absence of intercalary regeneration in combinations of fragments of different thoracic imaginal discs is a result of homology or identity of the positional information residing in the cells of the fragments. The pattern of correspondence of positional information revealed by this analysis is consistant with the pattern of homology determined by morphological observation and by analysis of the positional specificity of homoeotic transformation among serially homologous appendages. The implications of the existence of homologous positional information in wing and second leg discs which share a common cell lineage early in development are discussed.
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    Gap junctions are non-randomly distributed inDrosophila wing discs (1982)
    Springer
    Development genes and evolution 191 (1982), S. 335-339 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Gap junction ; Wing disc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The distribution of gap junctions in mature larvalDrosophila melanogaster wing discs was analyzed by means of quantitative electron microscopy. Gap junctions are non-randomly distributed in the proximal-distal disc axis and in the apical-basal cell axis of the epithelium. In the epithelial cells, the surface density, number and length of gap junctions are greatest in the apical cell region and distal disc region. The average gap junction surface density is 0.0572 μm−1 and 2.77% of the lateral cell surface is composed of gap junctions. In the adepithelial cells, the gap junction surface density is 0.0005 μm−1 and 0.06% of the cell surface is composed of gap junctions. No gap junctions were observed between epithelial cells and adepithelial cells. The absolute area of gap junctions was estimated in a proximal-distal strip of cells in the disc and is considerably less in the folded regions of the epithelium compared to the flat notum and wing pouch regions. The results are discussed with respect to pattern formation and growth control in imaginal discs.
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    Dicephalic — ADrosophila mutant affecting polarity in follicle organization and embryonic patterning (1982)
    Springer
    Development genes and evolution 191 (1982), S. 28-36 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Polarity ; Maternal effect ; Nurse cells ; Embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutationdicephalic (dic) affects follicle development and thereby alters the antero-posterior polarity of embryonic patterning. It maps at a single locus (3–46.0±1.0) and can be characterized as a semi-dominant maternal effect mutation with low penetrance. Indic follicles, the 15 nurse cells form two clusters located at opposite poles of the oocyte; the numerical distribution of the nurse cells among the clusters varies from 7:8 to 1:14. Thedic egg shell carries a micropyle (anterior marker) at either pole, but the misshapen respiratory appendages are restricted to one of the two poles in most eggs. The malformed eggs rarely yield larvae and these are always abnormal anteriorly and/or posteriorly. The segment pattern expressed in their cuticle may represent two anterior parts of opposite polarities (double head type), two posterior parts of opposite polarities (double abdomen type, rare) or show uniform polarity. Lability of organization at the cystocyte stage appears as the primary developmental defect of the mutant.
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    Development of imaginal discs from lethal hybrids betweenDrosophila melanogaster andDrosophila mauritiana (1983)
    Springer
    Development genes and evolution 192 (1983), S. 48-50 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Hybrid lethality ; Imaginal discs ; Interspecific transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Females ofDrosophila melanogaster, crossed with males ofDrosophila mauritiana, produce only female offspring. The male hybrid larvae grow very slowly, fail to pupate and die after prolonged larval life. Imaginal discs from these male hybrids transplanted into Drosophila melanogaster larvae can give rise to adult structures with normal patterns. Differentiation of hybrid imaginal disc tissue is improved by short term culture in non-hybrid larvae prior to metamorphosis, suggesting that the hybrid larval haemolymph is inadequate to sustain normal imaginal disc growth. This may represent the physiological basis of the reproductive isolating mechanism separating the twoDrosophila species
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    Three-dimensional fate map of the female genital disc ofDrosophila melanogaster (1983)
    Springer
    Development genes and evolution 192 (1983), S. 270-274 
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    ISSN: 1432-041X
    Keywords: Fate map ; Repressed primordium ; Sex determination ; Genital disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The female genital disc ofDrosophila melanogaster was cut into distinct fragments, and the prospective fates of the fragments were determined by putting them through metamorphosis in host larvae. The dorsal epithelium contains the anlagen for the anal plates and parovaria, as well as the repressed male genital primordium. The ventral epithelium gives rise to all of the female genital structures except for the parovaria. The results were compared with published fate maps and observations made in experiments with sex-transforming mutations. This allowed us to establish a detailed three-dimensional fate map of the female genital disc, which shows a well-developed female genital primordium in the ventral epithelium, a repressed male genital primordium in the anterior part of the dorsal epithelium and an anal primordium in the posterior region of the dorsal disc epithelium.
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    Cell degeneration and elimination in the imaginal wing disc, caused by the mutationsvestigial andUltravestigial ofDrosophila melanogaster (1983)
    Springer
    Development genes and evolution 192 (1983), S. 285-294 
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    ISSN: 1432-041X
    Keywords: Drosophila ; Cell degeneration ; Imaginal disc ; Basal lamina ; Blood cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutationsvestigial (vg; recessive) andUltravestigial (vg U; dominant) ofDrosophila melanogaster give rise to identical mutant adult phenotypes in which much of the cases this results from cell death in the presumptive wing margin of the wing disc in the third larval instar, but the process of cell degeneration is quite different in the two mutants. Invg cell death occurs continuously throughout the third larval instar, while invg U it occurs only in the early third instar. Cells fragment and some of the fragments condense, becoming electron dense (“apoptosis”). Both condensed and ultrastructurally normal cell fragments are extruded to the basal side of thevg disc epithelium. They accumulate under the basal lamina in the wing pouch area until they are phagocytosed by blood cells entering the wing pouch during the six hours following pupariation. Fragments are not extruded from thevg U epithelium but are apparently phagocytosed by neighboring epithelial cells. The basal lamina undergoes mophological changes following pupariation and is phagocytosed by blood cells in both wild-type andvestigial, but investigial the degenerated cell fragments are also engulfed by the same blood cells.
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    Topological specificity of phenotype expression of neurogenic mutations inDrosophila (1983)
    Springer
    Development genes and evolution 192 (1983), S. 317-326 
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    ISSN: 1432-041X
    Keywords: Neurogenic mutations ; Topological specificity ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Neurogenic mutations have been found to cause the neuralization of certain regions of the ectoderm and yet to permit normal development of the remaining embryonic cells. Thus, it seems that the activity of the wild-type alleles of these genes is dispensable in a considerable fraction of the embryo during wild-type development. This effect might be a consequence of the cells' position within the embryo; alternatively, it might be independent of the position but be due rather to the genetic activity experienced by the cells previous to their commitment. The results described in this paper indicate that genes controlling patterning along the embryonic dorso-ventral perimeter (dorsal and Toll) are epistatic to genes controlling neurogenesis, their activity deciding which ectodermal cells are susceptible to neurogenesis. Using alleles with low expressivity, evidence was obtained showing that the tracheal placodes define the boundary of the territory which has neurogenic abilities at thoracic and abdominal levels.
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    A clonal analysis of cell lineage and growth in the male and female genital disc ofDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 42-55 
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    ISSN: 1432-041X
    Keywords: Clonal analysis ; Growth ; Cell lineage ; Genital disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InDrosophila, the terminalia (i.e. internal and external analia and genitalia, except the gonads) are formed by the genital disc. Comparative studies suggested that this disc may have evolved through fusion of the imaginal primordia of the last 3 or 4 abdominal segments. The present report describes the clonal relationships within the complex genital disc. Genetically marked cell clones were induced in male and female embryos and larvae heterozygous for cell marker mutations. 1) Frequencies and sizes of clones suggest that the embryonic disc anlage consists of 14–17 precursor cells: 4–6 for the analia, some 7 for the male genitalia, and 3–4 for the female genitalia. These cells grow exponentially during larval development. 2) In both sexes, the clones were confined to either analia or genitalia, suggesting two separate cell lineages already established at blastoderm. 3) Internal and external genitalia remain in the same compartment at least up to 60 h (end of first instar). 4) A clonal restriction appeared around 84 h (mid second instar), separating a dorsal from a ventral part in the male genitalia. The ventral compartment comprises the ventral part of the lateral plate and clasper, hypandrium, and all internal genitalia. No such boundary was detected in the female. 5) In the female, analia and parovaria originate from the same precursors; another cell lineage forms eighth tergites, vaginal plates, oviduct, receptacle, and spermathecae. 6) In female analia, dorsal and ventral plate share common precursors at least up to 84 h. A medio-lateral boundary may appear at 84 h in the ventral anal plate. No clonal restriction was found in the male analia. 7) At all times, clones could cross between left and right sides of the symmetrical terminalia; they consistently did so via ventral structures. 8) The results are discussed in a phylogenetic context, and we propose that the clonal relations reflect the evolution of the complex genital disc.
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    Maternal effects of zygotic mutants affecting early neurogenesis inDrosophila (1982)
    Springer
    Development genes and evolution 191 (1982), S. 191-201 
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    ISSN: 1432-041X
    Keywords: Neurogenic mutants ; Maternal effects ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The size of the neurogenic region ofDrosophila melanogaster is under the control of several genes of zygotic expression. Lack of function from any of those genes produces an increase of the size of the neurogenic region at the expense of the epidermal anlage. However, differences exist in the extent of neuralisation achieved by each of the genetic loci upon mutation. The present results show that in the case ofN andmam phenotype differences are due to different contributions of maternal gene expression. This could be shown by studying the phenotype which appeared in mutant embryos when the oocytes developed from homozygous mutant precursor cells. Clones of mutant cells were induced in the germ line of females heterozygous for the neurogenic mutationin trans over germ line dependent, dominant female sterile mutations. After removing maternal information the phenotype ofN andmam mutants became identical in both cases. Furthermore maternal information fromN + was found to be necessary for viability of the wildtype.
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    Clonal analysis ofsex-lethal, a gene needed for female sexual development inDrosophila melanogaster (1982)
    Springer
    Development genes and evolution 191 (1982), S. 211-214 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Clonal analysis ; Sex determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutationSxl f , located on the X-chromosome, is a sex-limited recessive lethal that specifically kills 2X; 2A flies while it does not affect X; 2A flies (Cline 1978). We have analyzed the role ofSxl f on sex determination by a clonal analysis of a new spontaneous allele,Sxl fLS . Female embryos and larvae heterozygous forSxl fLS were irradiated at different times of development to generate homozygousSxl fLS clones which were recognized by linked marker mutations. We have studied the phenotype of such clones on sexually dimorphic regions of the fly (foreleg basitarsus, 5th, 6th and 7th tergites, analia and external genitalia). Despite their female (2X; 2A) chromosomal constitution, clones homozygous forSxl fLS differentiated male structures. These results confirm and extend the preliminary report of Cline (1979). They show that the wildtype product ofSxl f is required for female development.
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    On the phenotype and development of mutants of early neurogenesis inDrosophila melanogaster (1983)
    Springer
    Development genes and evolution 192 (1983), S. 62-74 
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    ISSN: 1432-041X
    Keywords: Early neurogenesis ; Neurogenic mutants ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The central nervous system (CNS) ofDrosophila develops from precursor cells called neuroblasts. Neuroblasts segregate in early embryogenesis from an apparantly undifferentiated ectoderm and move into the embryo, whereas most of the remaining ectodermal cells continue development as epidermal cell precursors. Segregation of neuroblasts occurs within a region called the neurogenic field. We are interested in understanding how the genome ofDrosophila controls the parcelling of the ectoderm into epidermal and neural territories. We describe here mutations belonging to seven complementation groups which effect an abnormal neurogenesis. The phenotypes produced by these mutations are similar. Essential features of these phenotypes are a conspicuous hypertrophy of the CNS accompanied by epidermal defects; the remaining organs and tissues of the mutants are apparently unaffected. The study of mutant phenotype development strongly suggests this phenotype to be due to misrouting into the neural pathway of development of ectodermal cells which in the wildtype would have given rise to epidermal cells, i.e. to an initial enlargement of the neurogenic region at the expense of the epidermogenic region. These observations indicate that the seven genetic loci revealed by the mutations described in this study contribute to control the neurogenic field. The present results suggest that in wildtype development neurogenic genes are supressed within all derivatives of the mesoderm and endoderm and some derivatives of the ectoderm, and conditionally expressed in the remaining ectoderm. The organisation of the neurogenic field in the wildtype is discussed.
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    Tissue-specific and substrate-specific detection of aldehyde and pyridoxal oxidase in larval and imaginal tissues of Drosophila melanogaster (1982)
    Springer
    Biochemical genetics 20 (1982), S. 315-332 
    Details
    ISSN: 1573-4927
    Keywords: aldehyde oxidase ; pyridoxal oxidase ; tissue specificity ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The substrate specificities of aldehyde and pyridoxal oxidases in Drosophila melanogaster have been determined with a variety of aliphatic and aromatic aldehydes. This analysis has led to the discovery that 2,4,5-trimethoxy-benzaldehyde is a specific substrate for pyridoxal oxidase, as based on the histochemical distribution of oxidase activity, the absence of enzymatic activity in the lpo 1strains, and the dosage dependence on the number of lpo +genes present. The tissue-specific localization of aldehyde oxidase (AO) and pyridoxal oxidase (PO) in the larval and adult structures showed that AO was present in all the major internal organs of the larvae and adults, including brain, imaginal discs, Malpighian tubules, digestive system, and reproductive structures. Pyridoxal oxidase is present in many of the same structures which possess AO, but is missing from the cardia, crop, imaginal discs, ovarian follicle cells, paragonia, pericardial cells, and wreath cells. The only structure which possesses PO but lacks AO is the larval salivary gland. These histochemical differences in AO and PO distribution were also confirmed by enzymatic analysis of the activities present in homogenates of ovaries, paragonia, and salivary glands. The general pattern of enzyme expression appears to be established during embryogenesis and maintained throughout the life of the individual.
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    Selection at the α-Gpdh locus in experimental populations of Drosophila melanogaster (1982)
    Springer
    Biochemical genetics 20 (1982), S. 461-474 
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    ISSN: 1573-4927
    Keywords: Drosophila ; allozymes ; α-Gpdh ; selection ; genetic background
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three sets of experiments have been conducted in order to evaluate the role of natural selection at the α-Gpdh locus in Drosophila melanogaster. (1) The evolution of the F-allele frequency has been followed for many generations in 13 experimental populations having different genetic backgrounds. (2) Egg-to-adult viability has been measured in synthetic populations derived from one locality (Brouilly) and the results have been compared with those of a previous experiment involving a different local population (Tostes). (3) The effects of sodium octanoate on egg-to-adult viability have been measured on the genotypes FF, FS, SF, and SS. The results demonstrate that selection operates on a small block of genes which includes the α-Gpdh locus.
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    An esterase duplication in Drosophila: Differences in expression of duplicate loci within and among related species (1982)
    Springer
    Biochemical genetics 20 (1982), S. 929-942 
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    ISSN: 1573-4927
    Keywords: esterase ; duplication ; gene expression ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract An esterase duplication is described in the sibling species pair Drosophila mojavensis and Drosophila arizonensis. We present evidence for two separate structural loci mapping at a distance of less than 0.16 recombination units from each other. Alleles at the two loci have the same substrate specificities and form small amounts of interlocus heterodimers. One locus (Est-5) is functioning throughout the insect's life cycle and appears at high concentrations in the hemolymph and the fat body. Its duplicate (Est-4) functions only during the late larval stage and is concentrated mainly in the carcass. No null alleles at either locus were observed in population surveys. An examination of 12 other species from the repleta group, to which D. mojavensis and D. arizonesis belong, suggests that Est-5 is universally present, but the activity levels of Est-4 vary among species and may be totally absent in some species. Variation in the level of Est-4 activity does not closely follow the phylogenetic relationship.
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    Drosophila lactate dehydrogenase: Developmental aspects (1983)
    Springer
    Biochemical genetics 21 (1983), S. 199-211 
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    ISSN: 1573-4927
    Keywords: Drosophila ; lactate dehydrogenase ; isozymic pattern ; development ; isozymic conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Partially purified lactate dehydrogenase (LDH) from third-instar larvae displays two bands (one major and one minor) on polyacrylamide gels. Analogous preparations from pupae and adults exhibit three LDH-staining bands (one major and two minor) in a similar pattern. The migration of the major band is similar for larvae, pupae, and adults, while the two minor LDH bands of pupae and adults migrate more slowly than the minor larval band. It has been shown that larval LDH incubated with β-nicotinamide adenine dinucleotide exhibits two additional minor bands with an electrophoretic mobility similar to that of the minor bands of both pupae and adults. The intensity of the minor larval LDH band (exhibited also by untreated preparations) is drastically reduced. This fact indicates that the life-cycle stage-dependent LDH isozymic distribution is possibly due to a posttranslational effect(s). Highly purified LDH from larvae, pupae, or adults, obtained by an affinity chromatography procedure, displays just one dispersed band, located in the area between the band 5 and the band 6 exhibited by crude extract preparations. These data, in combination with the lack of difference in catalytic properties among enzymes from larvae, pupae, and adults, suggest that LDH synthesis is controlled by the same single structural gene at all developmental stages.
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    The association between malathion resistance and acetylcholinesterase in Drosophila melanogaster (1982)
    Springer
    Biochemical genetics 20 (1982), S. 179-198 
    Details
    ISSN: 1573-4927
    Keywords: acetylcholinesterase ; Drosophila ; malathion ; insecticide resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The relationship between the 50% survival time for flies feeding on a malathion-containing medium and the activity of acetylcholinesterase (AChE) was determined for 15 isofemale lines of Drosophila melanogaster. A significant correlation was found (r=0.28, P〈0.05), with more resistant lines tending to have a lower level of AChE activity. An association between AChE and malathion resistance was also observed in a selection experiment. The AChE activity decreased in two of two populations selected for malathion resistance. AChE from these populations was altered in kinetic parameters (measured in crude head extracts) and electrophoretic mobility. Although the “resistant” AChE had a lower activity (V m) on either a per milligram protein or a per individual basis, its apparent K m for acetylthiocholine was lower than that of “susceptible” AChE. Recombination mapping of both low activity and fast electrophoretic mobility localized these traits to the region of the structural locus (Ace) on the third chromosome. The AChE activity of flies heterozygous for a variety of Ace lesions (kindly provided by Dr. W. M. Gelbart) was consistent with this location. The changes in AChE were suggested to have been caused by selection of alleles at the Ace locus.
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    Drosophila lactate dehydrogenase: Developmental aspects (1983)
    Springer
    Biochemical genetics 21 (1983), S. 199-211 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; lactate dehydrogenase ; isozymic pattern ; development ; isozymic conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Partially purified lactate dehydrogenase (LDH) from third-instar larvae displays two bands (one major and one minor) on polyacrylamide gels. Analogous preparations from pupae and adults exhibit three LDH-staining bands (one major and two minor) in a similar pattern. The migration of the major band is similar for larvae, pupae, and adults, while the two minor LDH bands of pupae and adults migrate more slowly than the minor larval band. It has been shown that larval LDH incubated with β-nicotinamide adenine dinucleotide exhibits two additional minor bands with an electrophoretic mobility similar to that of the minor bands of both pupae and adults. The intensity of the minor larval LDH band (exhibited also by untreated preparations) is drastically reduced. This fact indicates that the life-cycle stage-dependent LDH isozymic distribution is possibly due to a posttranslational effect(s). Highly purified LDH from larvae, pupae, or adults, obtained by an affinity chromatography procedure, displays just one dispersed band, located in the area between the band 5 and the band 6 exhibited by crude extract preparations. These data, in combination with the lack of difference in catalytic properties among enzymes from larvae, pupae, and adults, suggest that LDH synthesis is controlled by the same single structural gene at all developmental stages.
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    Alcohol dehydrogenase thermostability variants in Drosophila melanogaster: Comparison of activity ratios and enzyme levels (1983)
    Springer
    Biochemical genetics 21 (1983), S. 1071-1088 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; alcohol dehydrogenase ; enzyme polymorphisms, activity ratios
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Representatives of five allozymic classes of Drosophila alcohol dehydrogenase have been compared with respect to their activity levels on two alcohol substrates, quantities of ADH protein, and stability in crude extracts. Within each allozymic class, strains from widely diverse geographic locations differ in their enzyme activity levels but are identical for a measure known as “activity ratio,” which is obtained by dividing the average activity reading on isopropanol by that obtained with ethanol. They are also similar in the rate at which ADH activity declines in crude extracts held at 25°C. For several of the fast-resistant and fast-moderate strains, differences in ADH activity are associated with differences in the amount of enzyme present. The catalytic efficiencies of the fast-resistant forms are considerably lower than those of the fast-moderate allozymes. The origin and persistence of the rare but ubiquitous fast-resistant allozyme is discussed.
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    Genetic, ontogenetic, and tissue-specific variation of dipeptidases in Drosophila melanogaster (1982)
    Springer
    Biochemical genetics 20 (1982), S. 407-424 
    Details
    ISSN: 1573-4927
    Keywords: dipeptidases ; Drosophila ; variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three dipeptidases in Drosophila melanogaster are under independent genetic control and their structural genes have been localized, Dip-A to 2R and Dip-B and Dip-C to 3R (Voelker and Langley, 1978; Ohnishi and Voelker, 1981). These enzymes were characterized with respect to their substrate specificities, genetic variability (electrophoretic mobility and quantitative activity level), ontogeny (activity and isozyme pattern), and tissue localization. The dipeptide substrate specificities of DIP-A and DIP-B overlap each other considerably, but do not overlap with DIP-C. In natural populations, DIP-B and DIP-C are essentially monomorphic electrophoretically whereas DIP-A is polymorphic for three allozymes. Both DIP-A and DIP-B show quantitative genetic variation of activity level within an allozyme class. All three enzymes are expressed at all stages in the life cycle, but DIP-A and DIP-B activities vary considerably according to developmental stage and sex of adult. The tissue localizations of DIP-A and DIP-B activities show similar patterns and a nearly ubiquitous occurrence of both enzymes, but with particularly high values in larval and adult midguts and in the adult female reproductive system. These results suggest a general metabolic role for the enzymes, such as regulation of the concentrated pools of amino acids and oligopeptides found in Drosophila tissues.
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    URL: http://dx.doi.org/10.1007/BF00484692
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    Genetic localization and sequential electrophoresis of glucose-6-phosphate dehydrogenase in Drosophila melanogaster (1983)
    Springer
    Biochemical genetics 21 (1983), S. 703-711 
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    ISSN: 1573-4927
    Keywords: Drosophila ; glucose-6-phosphate dehydrogenase ; polymorphism ; sequential electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Studies were undertaken to investigate two critical aspects of the glucose-6-phosphate dehydrogenase polymorphism in Drosophila melanogaster. The first investigation unequivocally maps the genetic site of the G6PD locus to the X chromosome. The second study subjects a set of isochromosomal lines to sequential electrophoresis in an attempt to uncover common molecular heterogeneity within the global polymorphism, assuming that this variation may have gone undetected under conventional electrophoretic conditions. The genetic site was mapped following the segregation of the two common electrophoretic alleles, a so-called null allele, and two rare electrophoretic variants. From the pooled results, the Zw locus mapped to 62.9 on the X chromosome relative to the flanking markers car (at 62.5) and sw (at 64.7). A set of 126 iso-X chromosomal lines of diverse geographic origin was subjected to sequential electrophoresis under three different acrylamide conditions in addition to the conventional starch electrophoretic system. No additional variation beyond the common diallele polymorphism was seen.
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    URL: http://dx.doi.org/10.1007/BF00498917
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    Pupation site selection inDrosophila simulans (1983)
    Springer
    Behavior genetics 13 (1983), S. 17-27 
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    ISSN: 1573-3297
    Keywords: pupation site ; pupation height ; artificial selection ; Drosophila ; density-dependent behavior ; genotype-environment interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Selection for increased pupation height was carried out for 17 generations in two lines ofDrosophila simulans derived from a genetically heterogeneous base population. The realized heritability for mean pupation height in each line, calculated over the 17 generations, did not differ significantly from zero. Both selected lines tended to pupate away from the center of the culture medium to a greater extent than the control in the latter generations of the experiment but not in earlier generations. Pupation height may have been refractory to artificial selection because of an adaptation of this species to pupate on the larval food source. In a subsequent experiment, each line was tested at three larval densities in an apparatus different from the one used for selection. Each successively higher density showed a corresponding increase in pupation height. Both selected lines had higher mean pupation heights than the control line. The differences between lines became more pronounced as the larval density increased.
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    Selection at the alcohol dehydrogenase locus of Drosophila melanogaster: Effects of ethanol and temperature (1982)
    Springer
    Biochemical genetics 20 (1982), S. 681-688 
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    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; Drosophila ; selection ; ethanol ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Drosophila melanogaster larvae were subjected to 10 generations of selection on 6% ethanol at 17, 25, and 30°C. For each temperature there was a significant (P〈0.01) increase in the frequency of the Adh isoallele. Controls with no ethanol showed no change in the frequency of the Adh F isoallele. Larvae subjected to stronger selection on 8% ethanol confirmed the results. When adults of various ages were subjected to 16 and 32°C, the ADHF isoenzyme retained its twofold advantage in activity over ADHS regardless of the temperature. The same result was obtained with larvae at 16 and 35°C. Although some effect of temperature was demonstrated, it was concluded that the effect was not strong enough for temperature to be a selective factor under the conditions studied. However, ethanol is a strong selective factor for laboratory populations.
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    The effect of alcohol stress on nicotinamide adenine dinucleotide (NAD+) levels in Drosophila (1983)
    Springer
    Biochemical genetics 21 (1983), S. 365-374 
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    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; NAD+ levels ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Previous studies carried out in mammalian systems indicated that an organism's NAD+/NADH balance is carefully regulated but can be destabilized by dietary stresses. Since Drosophila alcohol dehydrogenase (ADH) uses NAD+ to remove a hydrogen from ethanol in the first step of alcohol catabolism, it is possible that under alcohol stress conditions the in vivo NAD+ levels in Drosophila may decrease. In this study genetically homozygous flies were stressed with maximally sublethal concentrations of ethanol (10%) for periods of up to 24 hr. The results indicate that NAD+ levels do in fact drop by at least 20% in response to ethanol stress. Evidence is presented that suggests that this decrease is the direct result of ADH-mediated catabolism.
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    Effects of disruptive selection on genetic variance (1983)
    Springer
    Theoretical and applied genetics 65 (1983), S. 173-180 
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    ISSN: 1432-2242
    Keywords: Disruptive selection ; Linkage disequilibrium ; Genetic variance ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Theoretical predictions of changes in variance with disruptive selection have used models of infinitely many genes so the increase in variance was necessarily due to linkage disequilibrium. With small numbers of loci, the disequilibrium is shown still to comprise the major part of the changes in variance. In a replicated experiment with Drosophila melanogaster, disruptive selection was practised for three generations, and this was followed by 5 or 7 generations of random mating. The heritability, as estimated from regression of progeny on parent, rose from 37% to 68% on selection, and subsequently declined to 45% on random mating. Changes of variance can be interpreted invoking the build up of linkage disequilibrium during selection followed by its breakdown upon relaxation. The results agree well with those obtained from Monte Carlo simulation.
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    Latitudinal variation in octanol dehydrogenase and acid phosphatase allele frequencies in Drosophila melanogaster (1983)
    Springer
    Theoretical and applied genetics 65 (1983), S. 191-196 
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    ISSN: 1432-2242
    Keywords: Drosophila ; Enzyme polymorphisms ; Latitudinal clines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The octanol dehydrogenase (Odh) and acid phosphatase (Acph) loci of Drosophila melanogaster are each polymorphic for two electrophoretically detectable alleles. The frequencies of the Odh and Acph alleles have been analysed in populations sampled from up to a 40 ° latitudinal range in each of Australasia, North America and Europe/Asia. Odh S frequency is found to be significantly negatively associated with distance from the equator in all three zones. The relationship of Acph S frequency to distance from the equator is significant and negative in Australasia but neither significant nor consistent in sign in North America and Europe/Asia.
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    Underreplication during polytenization? (1982)
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    Theoretical and applied genetics 63 (1982), S. 193-199 
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    ISSN: 1432-2242
    Keywords: Drosophila ; Polytene nuclei ; Underreplication ; Polytenization ; Cytophotometry ; Heterochromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Recent cytophotometric DNA determinations and results of labeling experiments are compared with results of biochemical experiments concerning larval polytene salivary gland nuclei of Drosophila melanogaster. Recent publications (Dennhöfer 1981; 1982 a, b) demonstrate that methodological errors both in hydrolysis of the DNA before Feulgen reaction and in interpretation of the cytophotometric values give raise to the hypothesis of heterochromatic underreplication during polytenization. It is concluded also that methodological difficulties cause the absence of polytene SAT-DNA in biochemical centrifugation experiments since, because of different solubilities of eu- and heterochromatic DNA, the latter is not resolved in DNA isolation procedures from polytene nuclei.
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    URL: http://dx.doi.org/10.1007/BF00303991
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    Genetic variation for anemotaxis (wind-directed movement) in laboratory and wild-caught populations ofDrosophilia (1982)
    Springer
    Behavior genetics 12 (1982), S. 281-293 
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    ISSN: 1573-3297
    Keywords: anemotaxis ; Drosophila ; habitat selection ; heritability ; wind-directed movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Two strains ofDrosophila melanogaster were selected for anemotactic response for six generations—one line for upwind response and one line for downwind response. A realized heritability estimate ofh 2=0.131 ±0.029 was obtained for the upwind response, and a realized heritability estimate ofh 2=0.012±0.014 was obtained for the downwind response. The divergent selection estimate wash 2=0.031±0.013. These values are consistent with previously reported heritability estimates for phototaxis and geotaxis, and serve to suggest that wind-oriented movement can be rapidly modified by selection under different habitat conditions. A comparison of wind response among wild-caught individuals of 11 species shows significant response differences between closely related species. Evaluation of these differences in light of the ecology of the flies suggests that upwind movement occurs among the monophagous species, which must move long distances to find their specific feeding sites, while downwind movement is more typical of polyphagous species. Species which are found in riparian or montane forest conditions showed a general reluctance to move under windy conditions. This corresponds to previous observations on these species and reflects the absence of wind generally encountered by these species during their natural periods of activity.
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    Cladoceran remains as evidence of change in trophic state in three Swiss lakes (1983)
    Springer
    Hydrobiologia 103 (1983), S. 141-146 
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    ISSN: 1573-5117
    Keywords: paleolimnology ; lakes ; sediments ; eutrophication ; Cladocera ; Switzerland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Species composition and density of cladoceran populations changed in Lakes Zürich, St. Mortiz and Baldegg as human populations increased in these watersheds. Lake Zürich sediments became annually laminated in the 1890's as a result of increased organic input as the size of the cities surrounding the lake grew. At the same time, the Bosmina species changed from a oligotrophic form (longispina) to a eutrophic form (longirostris). An increase in Daphnia spp. populations also occurred at this time in the lake's history. Bosmina longispina reappeared in the lake in 1965 as the lake's trophic status changed from eutrophic to mesotrophic due to effective sewage treatment facilities. Annual laminations appear in the Lake St. Moritz sediments about 1910. Shortly thereafter, a shift from B. longispina to B. longirostris occurred. This change in trophic status is associated with increased tourism in the area. Lake Baldegg sediments also show annual laminations beginning in 1885 and a similar shift in the Bosmina species. Other cladoceran remains were too scarce to be useful in interpreting the histories of these lakes.
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    Recent climatic changes recorded by the salinity of pore waters in the Dead Sea sediments (1983)
    Springer
    Hydrobiologia 103 (1983), S. 75-79 
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    ISSN: 1573-5117
    Keywords: paleolimnology ; Dead Sea climate ; pore-waters ; diffusion ; sediments ; salinity ; porosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The salinity of lakes is subject to variations imposed by climatic changes. These variations are recorded in the salinity profile of pore waters. Meromictic lakes, such as the Dead Sea, are a special case where waters which underlie the mixolimnion reflect salinity variations. In a sediment core from Dead Sea shallow waters, the salinity profile exhibited a minimum at about 1.9 m depth. It is shown by a diffusion model that this minimum can be attributed to lower salinities which prevailed at the sediment water interface for several decades around the turn of this century. No such minimum was observed in a sediment core from the deepest part of the lake where, during the last two centuries, the overlying brines had a constant salinity.
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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)
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    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)
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    Hydrobiologia 91-92 (1982), S. 235-240 
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    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.
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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 
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    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.
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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 
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    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.
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    Stratigraphic and dynamic effects of sediment reworking by Great Lakes zoobenthos (1982)
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    Hydrobiologia 91-92 (1982), S. 611-622 
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    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.
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    A new, flow-through corer for the quantitative sampling of surface sediments (1983)
    Springer
    Hydrobiologia 99 (1983), S. 75-79 
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    ISSN: 1573-5117
    Keywords: macrofauna ; meiofauna ; sediments ; methods ; coring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new, flow-through benthic corer is described and compared to other commonly used coring methods. The new corer compares favorably with diver coring and is superior to coring with a ball-type, check valve corer, based on recovery of meiofauna, macrofauna, and particle bound hydrocarbons. Check valve corers yielded the most variable results. The new corer may be used to efficiently obtain samples of surface sediments from shallow (〈6 m) water, where a reasonably stable working platform is available.
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    Transport of iron and manganese in relation to the shapes of their concentration-depth profiles (1982)
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    Hydrobiologia 91-92 (1982), S. 463-471 
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    ISSN: 1573-5117
    Keywords: iron ; manganese ; sediments ; water ; transport ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A model is presented which describes the transport of iron and manganese in the vicinity of a redox boundary. It is based on input of a particulate component, to form a point source, from which soluble species diffuse along a concentration gradient. The shapes of concentration-depth profiles in marine and freshwater sediments and water columns are reviewed and discussed in terms of the model. Transport, either entirely within a water column or within the sediment, may be simply treated because the rate of vertical transport can be regarded as constant. The discontinuity in the rate of vertical transport which occurs at the sediment-water interface can provide a complicated example of the model, especially when it coincides with the redox boundary. Authigenic mineral formation processes can modify the model, sometimes to such an extent that it becomes invalid. This is particularly true for soluble iron profiles in organically rich marine sediments. Sampling interval is critical to the resultant profile shape and must be relevant to the particular environment, e.g. metres in water columns and millimetres in sediments. The differences in the rates of reduction and oxidation of iron and manganese tend to modify both the position of the profile with respect to the redox-cline and its stage of development in a seasonally anoxic system. It is these factors which determine why most of the iron which reaches a sediment is permanently incorporated whereas manganese is re-released. This mechanism determines the average ratio of iron to manganese in sedimentary rocks. The development of peaked profile shapes in water columns implies that under certain conditions dissolved iron and manganese may be transported from the water column to the pore waters of the sediment.
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    Deepwater sediments and trophic conditions in Florida lakes (1982)
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    Hydrobiologia 91-92 (1982), S. 597-602 
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    ISSN: 1573-5117
    Keywords: eutrophication ; diagenesis ; sediments ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sediment cores were taken from near maximum depth in 15 Florida lakes representing a wide range of trophic conditions. Chemical analyses of surface sediments showed Al, Fe, and Ca to be the most abundant elements in all samples, and the ratio of Al to Ca to be smaller for eutrophic lakes. Sediment organic matter increased with trophic state, as did the degree to which it was enriched in nitrogen. Corresponding sediment C/N ratios decreased with increasing lake trophic state and showed significant negative correlation with chlorophyll a, total N, and total P in the water column. Concentrations of sedimentary chlorophyll derivatives showed some relation to trophic state but differences in basin morphometry hinder its use as an inter-lake index of chlorophyll production.
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    Experimental measurement of sediment nitrification and denitrification in Hamilton Harbour, Canada (1982)
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    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02391937
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    Introduction (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 1-1 
    Details
    ISSN: 1573-5117
    Keywords: symposium ; sediments ; freshwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00940091
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  • 100
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    Transport of iron and manganese in relation to the shapes of their concentration-depth profiles (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 463-471 
    Details
    ISSN: 1573-5117
    Keywords: iron ; manganese ; sediments ; water ; transport ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A model is presented which describes the transport of iron and manganese in the vicinity of a redox boundary. It is based on input of a particulate component, to form a point source, from which soluble species diffuse along a concentration gradient. The shapes of concentration-depth profiles in marine and freshwater sediments and water columns are reviewed and discussed in terms of the model. Transport, either entirely within a water column or within the sediment, may be simply treated because the rate of vertical transport can be regarded as constant. The discontinuity in the rate of vertical transport which occurs at the sediment-water interface can provide a complicated example of the model, especially when it coincides with the redox boundary. Authigenic mineral formation processes can modify the model, sometimes to such an extent that it becomes invalid. This is particularly true for soluble iron profiles in organically rich marine sediments. Sampling interval is critical to the resultant profile shape and must be relevant to the particular environment, e.g. metres in water columns and millimetres in sediments. The differences in the rates of reduction and oxidation of iron and manganese tend to modify both the position of the profile with respect to the redox-cline and its stage of development in a seasonally anoxic system. It is these factors which determine why most of the iron which reaches a sediment is permanently incorporated whereas manganese is re-released. This mechanism determines the average ratio of iron to manganese in sedimentary rocks. The development of peaked profile shapes in water columns implies that under certain conditions dissolved iron and manganese may be transported from the water column to the pore waters of the sediment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02391960
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