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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 105 (1996), S. 13-36 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We examine the equation of state of liquid4He at negative pressures close to the spinodal density ϱs where the hydrodynamic speed of sound vanishes. The non-analytic behavior of the equation of state and the speed of sound in the vicinity of the spinodal density are calculated in two and in three dimensions; we find for the speed of sound the non-analytic behavior mc s 2 ∼ (ϱ — ϱs)2/5 in three dimensions and mc s 2 ∼[(ϱ-ϱs)/¦ln(ϱ-ϱs)¦]1/2 in two dimensions. We then examine the low density regime numerically, using a semi-analytic microscopic theory. It is found that non-analytic exponents are visible only in a negligible density regime around the spinodal point. Estimates for the spinodal densities, and the range of critical fluctuations are provided.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Climatic change 40 (1998), S. 647-667 
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Recent studies on the nature of global warming indicate the likelihood of an asymmetric change in temperature, where night-time minimum temperature increases more rapidly than the day-time maximum temperature. We used a physically based scenario of asymmetric warming combined with climate change scenarios from General Circulation Models (GCMs) outputs and the EPIC (Erosion Productivity Impact Calculator) plant process model to examine the effects of asymmetric temperature change on crop productivity. Our results indicated that the potential effects of global change on crop productivity may be less severe with asymmetric day-night warming than with equal day-night warming.
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  • 13
    ISSN: 1573-5060
    Keywords: flower colour ; grass pea ; inheritance ; Lathyrus sativus ; neurotoxin (ODAP or BOAA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A strong epidemiological association is known to exist between the consumption of grass pea and lathyrism. A neurotoxin, β-N-Oxalyl-L-α, β-diaminopropanoic acid (ODAP) has been identified as the causative principle. This study was undertaken to investigate the mode of inheritance of the neurotoxin ODAP, flower and seed coat colour in grass pea. Five grass pea lines with low to high ODAP concentration were inter-crossed in all possible combinations to study the inheritance of the neurotoxin. Parents, F1 and F2 progenies were evaluated under field condition and ODAP analyzed by an ortho-phthalaldehyde spectrophotometric method. Many of the progenies of low x low ODAP crosses were found to be low in ODAP concentration indicating the low ODAP lines shared some genes in common for seed ODAP content. The F1 progenies of the low ODAP x high ODAP crosses were intermediate in ODAP concentration and the F2 progenies segregated covering the entire parental range. This continuous variation, together with very close to normal distribution of the F2 population both of low x low and low x high ODAP crosses indicated that ODAP content was quantitatively inherited. Reciprocal crosses, in some cases, produced different results indicating a maternal effect on ODAP concentration. Blue and white flower coloured lines of grass pea were inter-crossed to study the inheritance of flower colour. Blue flower colour was dominant over the white. The F2 progenies segregated in a 13:3 ratio indicating involvement of two genes with inhibiting gene interactions. The gene symbol LB for blue flower colour and LW for white flower colour is proposed.
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  • 14
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Surface runoff is the major way of P transport from agricultural land to surface waters. To assess the potential of P loss in runoff in relation to soil P status, the chemical nature and distribution of soil P in different size classes of water-stable aggregates were quantified for two distinctive soil types. For both soils unfertilized areas under pasture and well-fertilized arable soils were sampled. The content of total P, organic P and microbial biomass P (Pmic) decreased in the aggregate size order 〈0.1, 1–2, and 0.1–1.0 mm respectively. In contrast available P (extracted by Bray I reagent) was lowest in the 〈0.1 mm aggregate size. Cultivation decreased the percentage of 1–2 mm aggregates but increased that of the 〈0.1 mm aggregates. Fertilization increased markedly both total P and organic P in the 〈0.1 mm fraction of arable soils compared to the corresponding samples from unfertilized grassland soils. During aggregate separation, most of P loss was in the form of particulate P and less than 1% in solution. More organic P and Pmic were lost from the grassland soils than from the arable soils.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 101-105 
    ISSN: 1057-9257
    Keywords: biosensor ; protein immobilisation ; protein modification ; electrochemistry ; nitrotyrosine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Use of electrosynthetic methodology allows the production of hen egg-white lysozyme (HEWL) either mononitrated at tyrosine 23 or bisnitrated at tyrosines 20 and 23, but never nitrated at tyrosine 53. This is a different sequence from that obtained by the chemical nitrating agent tetranitromethane, and when reduced by dithionite, the selectively modified enzyme can be anchored at pH 5 via the unique aromatic amino group to magnetic beads or other suitable matrices. HEWL so immobilised loses less than 10% of cell-wall lytic activity compared with the approximately 50% loss of activity when immobilised by conventional methodology at pH 9 via essentially random reaction at lysine residues and other functionalities which are nucleophilic at this pH. This result offers promise as a general method for selective protein immobilisation in biosensors and similar applications. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 1 Tab.
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  • 16
    Publication Date: 1999-08-31
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 17
  • 18
    Publication Date: 1997-11-01
    Description: An 11-yr study was conducted on a coarse-textured Brown Chernozemic soil in the semiarid prairie of southwestern Saskatchewan. Soil was sampled after 3, 7 and 11 yr, and the results were used to assess the influence of fallow frequency and tillage on selected soil quality attributes [e.g., total soil organic C and N, microbial biomass C (MB-C) and microbial biomass N (MB-N), C mineralization (Cmin) and N mineralization (Nmin), and specific respiratory activity (SRA)] in the 0- to 7.5-cm and 7.5- to 15-cm depths. Although it took 11 yr before we observed significant treatment effects on total organic C or N, effects on Cmin and Nmin were observed in 7 yr in the 0- to 7.5-cm depth and by 11 yr, MB and SRA also showed significant treatment effects in this depth. Generally, soil quality attributes were greater in no-tillage (NT) systems than in conventional mechanical tillage (CT) or minimum tillage (MT), and greater in continuous wheat (Triticum aestivum L.) (Cont W) than in fallow-wheat (F-W) systems. With time, the labile constituents tended to increase under the Cont W cropping, but to decrease when F-W was coupled with MT. After 11 yr there was a strong, direct association between the labile attributes (viz., Cmin, Nmin and MB-C) in the 0- to 7.5-cm depth and the mean annual straw produced (kg ha−1yr−1) in the four cropping systems tested. Of the soil quality attributes tested, Cmin and Nmin were the most sensitive indices to tillage and fallow frequency effects. Key words: Mineralizable C, mineralizable N, microbial biomass, specific respiratory activity, crop residues
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 19
    Publication Date: 1998-08-01
    Description: The Environmental Policy Integrated Climate (EPIC) model is an important support tool for environmental management. Previous tests of the model have determined that it is suitable for long-term yield estimation, but it is less precise in assessing annual yield variability. To determine the reasons for the discrepancies between estimated and measured yields, we tested the ability of EPIC version 5300 to predict soil water and soil nitrogen dynamics, using data from a long-term spring wheat (Triticum aestivum L.) rotation experiment in the semiarid prairie region of Canada. Potential evapotranspiration (PET) estimates varied among methods tested: Priestley-Taylor and Penman-Monteith methods resulted in PET means that were about twice those obtained with the Hargreaves and Baier-Robertson methods. The higher PET means were associated with an excessive estimation of net radiation. We used the Baier-Robertson method to generate the other estimates reported herein. EPIC generally overestimated total soil water, but it still allowed clear differentiation among rotation phases and times of the year, and provided adequate estimates of water during the critical shot-blade stage. Water estimates by soil layer were also generally overpredicted, especially at depths from 0.15 to 0.60 m, but we were able to differentiate among rotation phases and times of the year. Precision of these latter estimates was generally low, accounting at most for 27% of the variability, and varied by soil layer, rotation phase and time of the year. Nitrate-N estimates tended to be lower than measured values, especially at depths below 0.3 m and during vegetative growth phases. However, the estimates also allowed us to distinguish among the rotation phases and times of the year. Total N and organic C were satisfactorily estimated by EPIC. In general, EPIC provided adequate long-term estimates of the environmental quality indicators tested. Key words: Environmental quality, environmental modelling, sustainability, spring wheat, fallow, potential evapotranspiration methods
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 20
    Publication Date: 1996-08-01
    Description: Soil organic matter contributes to the productivity and physical well-being of soils. An 11-yr study was conducted on a clay soil in the Brown soil zone in southwestern Saskatchewan to determine the influence of tillage and cropping frequency on soil organic C and total N content. Carbon and N behaved in a similar manner. Cropping frequency did not affect soil organic C or total N content, but soil C and N were greater under no-tillage (NT) than under mechanically tilled continuous wheat (Triticum aestivum L.) (Cont W) and fallow-wheat (F-W) rotations. Effects were apparent in the 0– to 7.5– and 7.5– to 15-cm depths. Over the 11-yr period, F-W (minimum tillage) gained no additional C; Cont W (conventional tillage) gained 2 t C ha−1, and both Cont W (NT) and F-W (NT) gained 5 t C ha−1. Changes in organic C and N were greatest in the final 4 yr of the experiment when crop residue production was greatest. Using data from two similar experiments conducted during the same period on soils differing in texture, we demonstrated that C gains were directly related to clay content of the soils. Thus, when attempting to estimate C storage in soils, we must consider both residue input and soil clay content. Key words: Organic C, total N, organic matter, soil texture, bulk density
    Print ISSN: 0008-4271
    Electronic ISSN: 1918-1841
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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