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  • 1
    Electronic Resource
    Electronic Resource
    Simulation of the nonlinear dynamics of grid sheath oscillations in double plasma devices (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 3933-3942 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The oscillation of ion bunches around a strongly negative grid in a double plasma device is studied with one–dimensional particle–in–cell simulation. The system exhibits feedback amplified virtual anode oscillations in the target chamber. The undriven system is shown to perform relaxation processes which can be described by the van der Pol equation for high nonlinearity. The periodically driven system exhibits nonlinear phenomena like mode locking and periodic pulling, which are in quantitative agreement with theoretical predictions for the driven van der Pol oscillator. For large driver amplitudes period doubling and weak chaos are found. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872514
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  • 2
    Electronic Resource
    Electronic Resource
    Nonlinear dynamical behavior of thermionic low pressure discharges. II. Experimental (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 1822-1836 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strongly nonlinear relaxation oscillations of discharge current and plasma potential are investigated in a magnetized thermionic plasma discharge. The quasi-one-dimensional electron motion allows a direct comparison with one-dimensional models and computer simulations. Two different stable discharge modes can be established, the low-current space charge limited and the high-current temperature limited mode. Time resolved probe measurements of the plasma potential distribution demonstrate that the current oscillations result from a strongly nonlinear instability of the potential structure in the weak current discharge mode. This confirms the model based on particle-in-cell simulations [F. Greiner et al., Phys. Plasmas 2, 1810 (1995)]. The oscillation process consists of three distinct phases. The sequence of events and the observed parameter dependencies of the oscillation frequency is in accordance with the model. The periodically driven system shows the characteristic behavior of nonlinear oscillators: quasiperiodicity, mode-locking, and period doubling sequences towards chaos. It is possible to link the complex dynamical behavior to the details of the trigger mechanism that are revealed by the simulation. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871336
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  • 3
    Electronic Resource
    Electronic Resource
    Van der Pol behavior of virtual anode oscillations in the sheath around a grid in a double plasma device (1997)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 2406-2412 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experiments are reported on oscillations that arise in a double plasma device when plasma production is restricted to the source chamber and the separating grid between the two chambers is biased negatively. The free oscillating system shows periodic pulling which is a typical behavior of driven van der Pol type oscillators. The second interacting frequency is identified to be half the ion plasma frequency at the sheath edge on the source side. With the help of particle in cell simulations the concept of virtual anode oscillations (VAO's) as the underlying oscillation mechanism is investigated and the van der Pol character of these is revealed. When applied to the experimental conditions, the VAO-model predicts correct oscillation frequencies. It gives a new interpretation of the scaling of these with plasma density and grid bias, and is compatible with earlier findings. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872221
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  • 4
    Electronic Resource
    Electronic Resource
    The ABSCISIC ACID-INSENSITIVE 3 (ABI3) gene is expressed during vegetative quiescence processes in Arabidopsis (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The ABSCISIC ACID-INSENSITIVE 3 (ABI3) gene of Arabidopsis thaliana (L.) Heynh is known to play an important role during seed maturation and dormancy. Here, we present evidence suggesting an additional role for ABI3 during vegetative quiescence processes. During growth in the dark, ABI3 is expressed in the apex of the seedlings after cell division is arrested. The 2S seed storage protein gene, a target gene of ABI3 in seeds, is also induced in the arrested apex under similar darkness conditions. In addition, β-glucuronidase expression under the control of the ABI3 promoter is abolished by treatments that provoke leaf development in the dark [sucrose and abscisic acid (ABA) biosynthesis inhibitors] and induced by treatments that prevent leaf development (darkness and ABA). Furthermore, ABI3 expression is absent in apices of dark-grown de-etiolated (det 1) and abi3 mutants, both known to develop leaves or leaf primordia in the dark. The fact that the expression of the ABI3 gene is only observed in a fraction of the analysed plants suggests that ABI3 is probably only one of the components of a molecular network underlying quiescence. In addition to the expression of ABI3 in apices of dark-grown seedlings, the ABI3 promoter confers expression in other vegetative organs as well, such as the stipules and the abscission zones of the siliques. In conclusion, apart from its role in seed development, ABI3 might have additional functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00428.x
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  • 5
    Electronic Resource
    Electronic Resource
    Room temperature molten polyiodides
    Amsterdam : Elsevier
    Electrochimica Acta 37 (1992), S. 379-383 
    Details
    ISSN: 0013-4686
    Keywords: electrical conductivity. ; molten salts ; polyiodides
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0013-4686(92)87025-U
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  • 6
    Electronic Resource
    Electronic Resource
    Validity of the negative/positive dichotomy for schizophrenic disorders under long-term conditions
    Amsterdam : Elsevier
    Schizophrenia Research 7 (1992), S. 117-123 
    Details
    ISSN: 0920-9964
    Keywords: (Schzophrenia) ; Longitudinal stability ; Negative symptom ; Positive symptom
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0920-9964(92)90041-3
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  • 7
    Electronic Resource
    Electronic Resource
    Modeling of net N-mineralization with a method of heuristic self-organization (GMDH) (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 336-341 
    Details
    ISSN: 1432-0789
    Keywords: Key words Agricultural soil ; Mineralization ; Modeling of net N-mineralization ; Heuristic self-organization ; GMDH ; Soil respiration ; Ammonification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It is possible to construct models, which describe and predict the annual course of net N-mineralization in agricultural soils, using the Group Method of Data Handling (GMDH), a method of heuristic self-organization. The advantage of this method is that complex ecosystems can be modeled without knowing anything about their structure and with only very few data points. The three input variables most often selected by GMDH for the different models have been soil temperature, soil water content and ammonification potential. Other parameters, which have been measured but usually not selected by GMDH as suitable input parameter for models of net N-mineralization are: substrate-induced respiration, soil respiration, mineralization potential, and microbial biomass C and N.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334579
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  • 8
    Electronic Resource
    Electronic Resource
    Stability of diagnoses in affective, schizoaffective and schizophrenic disorders (1991)
    Springer
    European archives of psychiatry and clinical neuroscience 241 (1991), S. 187-192 
    Details
    ISSN: 1433-8491
    Keywords: Functional psychoses ; Long-term course ; Stability of diagnosis ; Syndrome shift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study investigated the syndrome shift during the course of disease in 355 patients with functional psychoses. The mean observation time was 25.2 years. Every episode was diagnosed cross-sectionally as schizophrenic, melancholic, manic, manic-depressive mixed, schizodepressive, schizomanic or schizomanic-depressive mixed. With regard to the whole course, 148 patients fulfilled the diagnostic criteria of schizophrenic, 106 of affective and 101 of schizoaffective disorders. Patients with a schizophrenic initial episode showed the greatest stability: 90% had no other type of episode. The majority of patients who suffered a melancholic initial episode remained unipolar melancholics or developed manic symptomatology, and only a few suffered schizoaffective or schizophrenic episodes. Patients with a manic symptomatology at the beginning had a very unstable and changeable course. The stability of patients with initial schizodepressive episodes lay between that of patients with melancholic initial episodes and that of those with manic initial episodes. The findings demonstrate the relevance of longitudinal considerations in making the final diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02219720
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  • 9
    Electronic Resource
    Electronic Resource
    Modeling of net N-mineralization with a method of heuristic self-organization (GMDH) (1996)
    Springer
    Biology and fertility of soils 22 (1996), S. 336-341 
    Details
    ISSN: 1432-0789
    Keywords: Agricultural soil ; Mineralization ; Modeling of net N-mineralization ; Heuristic self-organization ; GMDH ; Soil respiration ; Ammonification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It is possible to construct models, which describe and predict the annual course of net N-mineralization in agricultural soils, using the Group Method of Data Handling (GMDH), a method of heuristic self-organization. The advantage of this method is that complex ecosystems can be modeled without knowing anything about their structure and with only very few data points. The three input variables most often selected by GMDH for the different models have been soil temperature, soil water content and ammonification potential. Other parameters, which have been measured but usually not selected by GMDH as suitable input parameter for models of net N-mineralization are: substrate-induced respiration, soil respiration, mineralization potential, and microbial biomass C and N.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334579
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    The concept of distinct but voluminous groups of bipolar and unipolar diseases (1990)
    Springer
    European archives of psychiatry and clinical neuroscience 240 (1990), S. 85-89 
    Details
    ISSN: 1433-8491
    Keywords: Affective disorders ; Schizoaffective disorders ; Unipolar diseases ; Premorbid features ; Long-term course and outcome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Seventy-six unipolar affective and 45 unipolar schizoaffective patients were compared using the same instruments as mentioned in part I of this study (this issue). In contrast to bipolar diseases significant differences regarding age at onset were found between the unipolar groups: schizoaffective unipolar patients became ill at a significantly lower age than affective unipolar patients (about 8 years). No other sociodemographic differences were found between the two groups. Patterns of course were found to be similar in both unipolar groups. Unipolar affective patients had a more favourable long-term outcome (GAS and WHO/DAS) than unipolar schizoaffective ones. Altogether, unipolar affective and unipolar schizoaffective disorders seem to have more similarities than differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02189976
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