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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 78 (1996), S. 135-142 
    ISSN: 1570-7458
    Keywords: vascular bundles ; feeding preferences ; salivary sheaths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study revealed strong evidence that nymphs of the silverleaf whitefly, Bemisia argentifolii Bellows and Perring, are obligate feeders on vascular bundles and that there are large differences between different host plants as to the availability of vascular bundles to silverleaf whitefly nymphs. The relationship between nymphs and leaf vascular bundles was studied using 1) leaf sectioning and 2) techniques of leaf clearing of intact leaves. A geometric model is presented of the feeding relationship of vascular bundle-using homopterans. The relative abundance of vascular bundles was examined in six species of host plants that varied from highly preferred to tolerably acceptable. Included in order of acceptance were cantaloupe, cotton, hibiscus, broccoli, lantana and lettuce. The length of vascular bundle per 1.0 mm2 of leaf surface ranged from about 10 mm in cantaloupe to 2.8 mm in lettuce. Salivary sheaths were found to connect with vascular bundles in 100% of the intact nymphs examined by the staining and clearing technique. However only 64% of those examined by the sectioning technique appeared to be connected to vascular bundles. This indicates that the sectioning technique leads to a high rate of error, causing an underestimation of the importance of direct contact with vascular bundles. About 50% of epidermal stylet penetrations were through epidermal cells; the remaining 50% went through intercellular junctions. On cotton leaves, the distance between the point of labial contact with the leaf surface and the nearest point of the vascular bundle rarely exceeded 60 μm. Our studies show that while 50% of lettuce leaf-surface was beyond 60 μm of a vascular bundle, only 10% of cantaloupe leaf surface area was outside of the 60 μm range. In cotton, mean distance from labium to the nearest point of the vascular bundle was 40.9 μm (SEM=2.66, N=50, range 0–80 μm). Over 98% of all salivary sheaths went to minor veins (78% to single-filament vascular bundles, nearly 20% to double filament bundles). Fewer than 2% went to bundles with 3 or more filaments.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of intelligent manufacturing 8 (1997), S. 385-403 
    ISSN: 1572-8145
    Keywords: Supply management ; stochastic optimization ; discrete event systems ; continuous flow models ; gradient descent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper is concerned with inventory control in assembly systems for minimizing production costs. The system manufactures multiple products assembled from various components, and it operates according to a cyclic schedule. At the start of each cycle time, two decisions are made: the product volumes to be assembled during the current cycle, and the component-stock levels to be ordered. For a given decision, there is an associated cost incurred by backlogging of the finished products on one hand, and the component inventory holding cost, on the other hand. The objective here is to balance the two costs so as to minimize their sum. One complicating factor stems from uncertainties in both product demand levels and components yield times. These uncertainties can be modelled by probabilistic means, and hence the cost minimization problem becomes a stochastic problem. This problem can be quite difficult due to the nonlinearity of the equations involved, the mix of integer and continuous parameters, and their large number in moderate-size problems. Our approach in this paper is to first define certain control parameters and thus reduce the number of the variables involved in the optimization problem, and then solve the latter problem by using sophisticated optimization techniques in conjunction with heuristic modelling. We will demonstrate, by numerical means, the resolution of fairly difficult problems and thus establish the viability of the proposed numerical techniques.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 28 (1996), S. 1463-1476 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have observed a fixed wavelength emission at 178.7 nm in sodium vapour under 578.7 nm two-photon resonance excitation. The proposed non-linear wave mixing scheme is described by ω178.7 nm = 2ωL + ω465.7 nm; where ω178.7 is the 178.7 nm photon frequency, ωL is the laser-photon frequency, and ω465.7 is the 465.7 nm photon frequency. This 465.7 nm emission comes from another six-wave mixing process involving two hyper-electronic Raman scattering photons. The excitation spectrum of the 178.7 nm emission has a typical multiwave mixing pattern with a competing effect appearing at higher temperatures under two-photon resonance excitation. Numerical analysis indicates that this vacuum ultraviolet emission has a poor phase-match condition that will depress the emission intensity to a certain extent. This makes the observation more difficult compared with other reported four-wave mixing generated emissions. Fortunately, on the one hand, it is enhanced by quasi-auto-ionization resonance when the 3s–5s transition is coupled to the sodium continuum by a 330.2 nm photon. On the other hand, its wavelength sits so close to the sodium Cooper minimum that weak absorption will not suppress this vacuum ultraviolet emission further.
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  • 4
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plants of Diplacus aurantiacus, a successional shrub common in California chaparral, were grown under controlled conditions in which either quantum flux density or nitrogen availability was varied. Photosynthesis and leaf nitrogen content were determined on a leaf area and a leaf weight basis, and whole plant growth was monitored. There was a direct relationship between photosynthesis and leaf nitrogen content on both area and weight bases. Reduced light intensity of the growth environment resulted in reductions in light-saturated photosynthesis and nitrogen content on an area basis, but not on a weight basis. With reduced nitrogen availability, photosynthesis and leaf nitrogen content per unit leaf weight decreased. Resource use efficiency increased as the resource became more limiting. The results are consistent with a model of plant growth in which net carbon gain of the leaf is maximized.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 57 (1983), S. 148-150 
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plants of two populations of Diplacus aurantiacus, a subshrub of the Californian chaparral, were compared for their stomatal response to water vapor concentration gradients. Plants of a coastal and an interior population were compared when grown under both low and high humidities. When grown at high humidity the coastal plants exhibited higher conductances and higher transpiration/photosynthesis ratios at all leaf-to-air water vapor concentration gradients than did the interior plants. Although all of the plants examined showed a pronounced stomatal response to humidity the response did not result in the degree of regulation of water-use efficiency reported for other Californian coastal species.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 58 (1983), S. 33-42 
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water resource partitioning among three co-occurring species of the California annual grassland was investigated. Plantago erecta, Clarkia rubicunda and Hemizonia luzulifolia differ in lifespan. The lifespan of Plantago is coincident with the October–May rainy season, but the other two species reproduce during summer when no precipitation occurs, and thus depend on stored water. Field studies indicated differential access to stored water commensurate with the phenology of each species. Studies of artificial stands under controlled conditions showed no difference in the species' ability to exploit stored water in the soil. However there was a striking difference in root behavior between Plantago and Hemizonia when plants were grown in a soil layer above a non-nutritive, waterstoring substrate. We concluded that Hemizonia, the longest lived species, survives on water stored in decomposed rock below the soil layer. Clarkia is restricted to cooler slope faces where a slightly longer growing season appears just suficient to complete reproduction. Productivity is enhanced by addition of later blooming species to the community, but there is no indication that the mixture is the most productive system.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0630
    Keywords: PACS: 68.35; 72.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 2 tungsten lamp at 1.83 mA excited by a 0.85-mW 675-nm laser diode. We also demonstrate that the dark current could be greatly reduced through rapid thermal oxidation and rapid thermal annealing.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of advanced manufacturing technology 9 (1994), S. 79-86 
    ISSN: 1433-3015
    Keywords: Homogeneous coordinate transformation ; Metrology pallet ; Quasi-static error ; Rigid-body kinematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A method for characterising machine tool accuracy is presented in this paper, using a compact quasi-static error model of a three-axis horizontal machining centre. Rigid-body kinematics and homogeneous coordinate transformation were used in this model. A metrology pallet was designed so that coefficents in the error model can be updated periodically. Ten measurement points were allocated on two perpendicular planes of the metrology pallet. One of the measurement planes was on the work table and the other was perpendicular to the table. Two different length touch trigger probes were required for error measurements. Establishing or updating the error model can be carried out in-process without disturbing the workpiece setup. The proposed compact error model is an improvement over past work for a production environment because of its robustness and convenient calibration procedure. The error model was tested in two dimensions and a good error prediction capability was observed in warm machine states.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-9605
    Keywords: phase transitions ; ruthenate–cuprate ; superconducting ferromagnets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have systematically investigated the magnetic, electrical, and structural properties of the high-purity superconducting ferromagnet RuSr2GdCu2O8, in which superconductivity and significant ferromagnetism have been reported to coexist. Our results show that there may exist in this compound a novel superconducting state which is characterized by the absence of a bulk Meissner effect, the presence of negligible superconducting condensation energy, and the appearance of an unusually large effective penetration depth. Such a state appears to have a nonuniform filamentary structure existing in the less magnetic walls between the ferromagnetic domains or a fine-grain structure beset by ferromagnetic walls between antiferromagnetic “domains,” similar to the case of NdNi2B2C. These results are presented and contrasted with the recently reported Meissner effect in RuSr2GdCu2O8 in terms of the various phase transition sequences predicted.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 12 (1999), S. 85-88 
    ISSN: 1572-9605
    Keywords: High temperature superconductivity ; materials ; occurrence ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Over the last 12 years, impressive progress has been made in characterizingthe high temperature superconducting phenomenon and in discovering trendsabout its occurrence. As a result, many models have been advanced to accountfor the observations. In this presentation, I would like to discuss a fewissues that may be important to the understanding of high temperaturesuperconductivity but have not yet been given the attention they deserve inthe development of theoretical models.
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