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  • 1
    ISSN: 1432-0789
    Keywords: Key words Abundance ; Biomass ; Diversity ; Earthworm community ; Tropical savannas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The structure and seasonal changes of earthworm communities were evaluated in a natural savanna and in a improved grass-legume pasture in a Colombian oxisol over a period of 18 months. One plot of 90×90 m was isolated in each of the systems and each month five samples of 1 m2×0.5 m and ten of 20×20×20 cm were randomly selected from a stratified block design. Species richness was similar in the two evaluated plots (seven species), whereas diversity measured by the index, H (Shannon and Weaver 1949) was clearly different, i.e. H=2.89 in natural savanna and H=1.29 in pasture. This is explained by differences in earthworm community structure. The average annual density in the savanna was 49.8, ranging from 10.8 to 135.8 individuals (ind) m–2, and biomass was 3.3 g m–2 (hand-sorting method), ranging from 0.9 to 11.5 g m–2. In the man-made pasture, density was 80.1 ind m–2 on average, ranging from 24 to 215.8 ind m–2 and biomass was more than tenfold higher, ranging from 29.2 to 110.4 g m–2. This was especially due to the presence of a large glossoscolecid anecic species, Martiodrilus carimaguensis Jiménez and Moreno, which has been greatly favoured by conversion of savanna to pasture. Endogeic species were dominant in the natural savanna whereas the anecic species accounted for 88% of total earthworm biomass in the pasture. Total earthworm density and biomass were significantly different in the two systems studied (t-test). The results indicate a clearly positive response of earthworm communities to improved pastures, a type of land use that is being increasingly adopted in moist neotropical savannas.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2242
    Keywords: Key words Plant virus resistance  ;  Azuki bean mosaic virus  ;  Cowpea aphid-borne mosaic virus  ; Soybean mosaic virus  ;  Watermelon mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have examined the genetics of systemic resistance in Phaseolus vulgaris to azuki bean mosaic virus (AzMV) and cowpea aphid-borne mosaic virus (CABMV) and the relationship of this resistance to a phenotypically similar resistance to watermelon mosaic virus (WMV) and soybean mosaic virus (SMV). In P. vulgaris cv ‘Great Northern 1140’ (GN1140), resistance to SMV and WMV has been attributed to the genes Smv and Wmv, respectively, which have been shown to segregate as a unit. Systemic resistance to AzMV is conferred by two incompletely dominant alleles, Azm1 and Azm2, at unlinked loci. At least three resistance alleles must be present at these two loci for systemic resistance to be expressed in the plant. Systemic resistance to CABMV in GN 1140 is conditioned by a dominant allele that has been designated Cam2. Under some environmental conditions, a recessive allele at an unlinked locus, cam3, also controls a resistant response to CABMV. Resistance to AzMV and CABMV does not assort independently from Wmv/Smv, but also does not consistently cosegregate, suggesting that perhaps in each case one of the factors involved in resistance is associated with Smv/Wmv.
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  • 3
    ISSN: 1432-2242
    Keywords: Plant virus resistance ; Azuki bean mosaic virus ; Cowpea aphid-borne mosaic virus ; Soybean mosaic virus ; Watermelon mosaic virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have examined the genetics of systemic resistance in Phaseolus vulgaris to azuki bean mosaic virus (AzMV) and cowpea aphid-borne mosaic virus (CABMV) and the relationship of this resistance to a phenotypically similar resistance to watermelon mosaic virus (WMV) and soybean mosaic virus (SMV). In P. vulgaris cv ‘Great Northern 1140’ (GN1140), resistance to SMV and WMV has been attributed to the genes Smv and Wmv, respectively, which have been shown to segregate as a unit. Systemic resistance to AzMV is conferred by two incompletely dominant alleles, Azm1 and Azm2, at unlinked loci. At least three resistance alleles must be present at these two loci for systemic resistance to be expressed in the plant. Systemic resistance to CABMV in GN 1140 is conditioned by a dominant allele that has been designated Cam2. Under some environmental conditions, a recessive allele at an unlinked locus, cam3, also controls a resistant response to CABMV. Resistance to AzMV and CABMV does not assort independently from Wmv/Smv, but also does not consistently cosegregate, suggesting that perhaps in each case one of the factors involved in resistance is associated with Smv/Wmv.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Formal aspects of computing 7 (1995), S. 533-549 
    ISSN: 1433-299X
    Keywords: Modal and temporal logics ; Reactive systems ; Specification ; Prototyping ; Mechanical verification ; Non-procedural languages ; Logic programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper a methodology for the use of temporal logic as an executable imperative language is introduced. The approach, which provides a concrete framework, calledMetateM, for executing temporal formulae, is motivated and illustrated through examples. In addition, this introduction provides references to further, more detailed, work relating to theMetateM approach to executable logics.
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new high-resolution soft x-ray beamline utilizing a variable line density grating has been constructed and tested at SRC. In addition to normal grating rotation, the grating housing mechanism allows a translation of the grating. This additional motion of the grating can be used in such a way that grating aberration effects such as defocus, coma, and spherical aberrations are minimized over the entire scan range. In order to achieve the theoretical resolving power of 105–5000 over the photon energy range of 280–1150 eV, extreme care had to be exercised in positioning and controlling the grating scan angle (〈0.12 arcsec) and focus drive position (〈10 μm). Using a spherical grating with a figure error of 〈0.2 arcsec and 10 μm slits, we were able to experimentally reproduce our theoretical predicted energy resolution over a wide energy range. We present photoabsorption data of the K-shell edges and associated Rydberg states of Ne, O2, and CO. The high-resolution monochromator unveils structures which were previously not seen or only poorly resolved. A quantitative data analysis of the Ne absorption peak shows the intrinsic lifetime broadening of the Ne 1s state agrees well with theoretical estimates. © 1995 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 376 (1995), S. 473-473 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] FISHER ETAL. REPLY - The comments by Davidson et al. about the rainforests and the wooded communities of the cerrados are not relevant to our paper1, which was about the 35 million hectares (MHa) of treeless grasslands in Colombia and Venezuela and the 50 MHa (24%) of the cerrados of ...
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  • 7
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: For many decades, anaerobic digestion has been the most important technique of sewage sludge treatment at larger sewage-treatment works. Also, the low running costs of the process make it attractive for the treatment of strong industrial effluents. This paper reviews these advantages and discusses some disadvantages of the anaerobic treatment of industrial effluent. Operating and cost data are presented from Europe and from a detailed UK case study which supports the conclusion that anaerobic treatment will be the most cost-effective method of treatment of strong industrial effluents such as those from food and paper processing.
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  • 8
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report on the design and testing of an ultrasensitive, electromechanical transducer for use on resonant mass gravitational wave antennae. The transducer is a superconducting, radio frequency resonant bridge circuit operating near 200 MHz. We have minimized several important sources of noise in this transducer system. The Johnson noise of the transducer circuit is reduced through using a superconducting niobium stripline circuit and low-loss insulating materials. At a temperature of 4.2 K we have achieved unloaded electrical quality factors of 200 000. The bridge circuit is balanced by piezoelectric actuators which control the spacing between the proof mass and capacitive segments of the stripline circuit and we have achieved a residual bridge imbalance of 3×10−7. Finally, low noise cryogenically cooled field-effect transistors are used for the first amplifier stage, enabling us to obtain an amplifier noise level which is 5400 times the quantum limit. The transducer, which has a 0.080 kg proof mass, was affixed to the end of a prototype, resonant bar, gravitational wave antenna with a mass of approximately 100 kg. The primary purpose of this small antenna was to evaluate the transducer, which is designed to be mounted on a much more massive antenna. Our theoretical analysis and measurements of the detector agree and indicate a burst noise temperature of 1.8 K using the 100 kg bar. This corresponds to a gravity wave burst sensitivity of h=1.1×10−16, in terms of relative strain amplitude. With no other improvements, if the transducer mechanically resonant frequency were tuned to and installed on a 2000 kg antenna, the antenna would reach a noise temperature of 1.3 mK, which is equivalent to a gravitational wave burst sensitivity, h≈5.7×10−19. © 1995 American Institute of Physics.
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  • 9
    ISSN: 1573-8450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper, we consider a class of nonlinear optimal control problems subject to control constraints. We assume that an initial condition for the dynamical system is specified. Then, we can easily compute an openloop optimal control using any convenient optimal control software package. Now, suppose the optimal trajectory is perturbed due to a change in initial conditions or uncertainty in the model equations. If the perturbations are not too large, it is known that the neighbouring extremal approach can be used to obtain a feedback law which adjusts the open-loop optimal control accordingly provided there are no bounds on the control variables. In this paper, our aim is to develop a computational method for the more general case of fixed-time problems with control constraints.
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  • 10
    ISSN: 1573-8450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A new algorithm is presented for providing under-estimates of the reachable set from the origin for a class ofn-dimensional linear systems with bounded controls. This algorithm is based on the novel approach of choosing a feedback control which makes all the eigenvalues of the closed loop system unstable. Results from feedback control and Liapunov stability theory are then used to formulate the problem as the minimization of a nonlinear function subject to constraints on certain matrices. The solution of this optimization problem provides an under-estimate of the reachable set in the form of ann-dimensional ellipsoid. Examples of both continuous and discrete-time systems are presented to illustrate the method. Comparison with existing exact results for some 2-dimensional systems shows that the method provides good approximations in these cases.
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