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  • 1
    Electronic Resource
    Electronic Resource
    Influence of domain size on optical properties of ordered GaInP2 (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2633-2639 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using dark-field transmission electron microscopy images of ordered GaInP samples, we show how the ordering domain size depends on the growth temperature. Samples with different average domain sizes are compared with regard to their photoluminescence (PL) and excitation spectra. We find a close correlation between the size of the ordered domains and the relative intensity of the PL peak from band–band recombination compared with the rapidly shifting, below-band-gap luminescence emission. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361099
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  • 2
    Electronic Resource
    Electronic Resource
    Enhanced carrier collection observed in mechanically structured silicon with small diffusion length (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 7179-7182 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The diffusion length of minority charge carriers in the silicon bulk Ldiff is an important characteristic of optoelectronic devices fabricated from low cost silicon wafers. In this study computer simulations have been carried out to calculate the beneficial effects of a macroscopic surface texturization on the charge carrier generation and the collection probability. Textured solar cells should be able to collect charge carriers more effectively resulting in an increased current due to the special emitter geometry resulting from the texture, decreased reflection losses, and the inclined penetration of the light. In order to prove this expected behavior, deeply V-textured solar cells have been processed and characterized on low cost silicon reaching an Ldiff of about 25 μm. Spatially resolved high resolution measurements of the internal quantum efficiency exhibit a strongly increased signal in the texture tips which is the first experimental proof of the increased charge carrier collection probability of deeply textured solar cells. This effect can further be seen in cross sectional electron beam induced current measurements and the mechanical texture results in an overall gain in short circuit current density of about 11% and in efficiency of about 8% relatively. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371809
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  • 3
    Electronic Resource
    Electronic Resource
    The Human Bone Morphogenetic Protein 4 (BMP-4) Gene: Molecular Structure and Transcriptional Regulation (1998)
    Springer
    Calcified tissue international 63 (1998), S. 221-229 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Bone morphogenetic protein 4 — Gene structure — Gene organization — Transcriptional regulation.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Bone morphogenetic protein 4 (BMP-4) is a vital regulatory molecule that functions throughout human development in mesoderm induction, tooth development, limb formation, bone induction, and fracture repair and is overexpressed in patients who have fibrodysplasia ossificans progressiva. The human gene encoding bone morphogenetic protein 4 (BMP-4) has been isolated and its structural organization characterized. The complete DNA sequence of an 11.2 kb region has been determined. BMP-4 mRNA is transcribed from four exons, although there is evidence that alternate first exons may be used. Transcript initiation occurs at variable positions within a GA-rich region of the DNA. The promoter region is GC-rich with no obvious TATA or CAAT consensus sequences, and contains both positive and negative transcriptional regulatory elements within the 3 kb 5′ flanking region of the RNA start site. Comparison of the human and murine BMP-4 genes reveals highly conserved sequences not only in the exon-coding regions but also within the introns and 5′ flanking regions. BMP-4 localizes to human chromosome 14q21 by fluorescence in situ hybridization, a location more centromeric than that recently reported. These studies provide a foundation for understanding the genetic regulation of this important gene in human development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900518
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  • 4
    Electronic Resource
    Electronic Resource
    Quantifying livestock responses for heat stress management: a review (1999)
    Springer
    International journal of biometeorology 42 (1999), S. 183-188 
    Details
    ISSN: 1432-1254
    Keywords: Key words Biological response ; Dynamic analyses ; Thresholds ; Decision support ; Thermal stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract  Hot weather challenges livestock production but technology exists to offset the challenge if producers have made appropriate strategic decisions. Key issues include understanding the hazards of heat stress, being prepared to offer relief from the heat, recognizing when an animal is in danger, and taking appropriate action. This paper describes our efforts to develop biological response functions; assesses climatic probabilities and performs associated risk analyses; provides inputs for computer models used to make environmental management decisions; and evaluates threshold temperatures as estimates of critical temperature limits for swine, cattle and sheep.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004840050103
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  • 5
    Electronic Resource
    Electronic Resource
    Callose in roots of Norway spruce (Picea abies (L.) Karst.) is a sensitive parameter for aluminium supply at a forest site (Höglwald) (1998)
    Springer
    Plant and soil 199 (1998), S. 53-57 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; callose ; Norway spruce ; rooth growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under controlled environmental conditions in nutrient solution experiments induction of non-constitutive callose in roots has been shown to be a symptom of aluminium (Al) toxicity. In the present study roots of Norway spruce were sampled from a forest site where soil conditions had been modified by acidic irrigation and liming (Höglwald Experiment in Bavaria, Germany). A significant positive relationship was found between the callose content in short roots and the Al concentration in the soil solution, particularly if free Al, rather than total concentrations of soluble Al, were used for prediction. At the same sites root growth of Norway spruce was not affected by free Al concentrations in the range of 2.5 to 199 µM Al. The results show that also under field conditions a positive relationship between Al supply and callose content can be established. In Norway spruce callose content in roots is a much more sensitive parameter for Al supply than root growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004212017912
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of acid irrigation and liming on root growth of Norway spruce (1998)
    Springer
    Plant and soil 199 (1998), S. 11-22 
    Details
    ISSN: 1573-5036
    Keywords: acid irrigation ; aluminium ; liming ; Picea abies ; root growth ; root window
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of acid irrigation and liming on fine root growth of Norway spruce (Picea abies [L.] Karst.) was studied in an approximately 80-year-old forest stand in southern Germany (Höglwald). Root growth was measured mainly on root windows and in addition by soil core sampling. Root growth rate showed a typical pattern in the course of a year with a maximum in August. Acid irrigation depressed root growth rate, whereas liming, particularly in combination with acid irrigation, markedly increased root growth in the humic layer and the upper 0–5 cm of the mineral soil. The treatment effects on root growth in the mineral soil below 5 cm were small and not significant. Root growth rate was not correlated with the concentration of aluminium (Al) or the molar ratio of calcium (Ca) to Al in the soil solution. The results suggest that inhibition of root growth by acid irrigation is a direct effect of high proton concentrations in the irrigation water, and that enhancement of root growth by liming is caused by an improved supply of mineral nutrients and higher biological activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004254709452
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  • 7
    Electronic Resource
    Electronic Resource
    Cation concentrations of short roots of Norway spruce as affected by acid irrigation and liming (1998)
    Springer
    Plant and soil 199 (1998), S. 23-27 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; calcium ; magnesium ; Picea abies ; root content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The longterm effect of acid irrigation and liming (dolomitic limestone) on the mineral element content of roots of Norway spruce (Picea abies [L.] Karst.) was investigated in an 80-year-old Norway spruce stand in South Germany (Bavaria). Soil cores of four soil depths (humic layer, 0–10, 10–20 and 20–30 cm) were taken over 2 years (August 1991 and August 1992) from six plots with different treatments (control, normal irrigation, acid irrigation solely or in combination with liming) and living short roots selected and analysed for calcium (Ca), magnesium (Mg), manganese (Mn) and aluminium (Al). On the acid irrigated plot, the Ca and Mg contents of roots were decreased in 1991, but by 1992, 2 years after the irrigation had been terminated, no difference could be found. The Al content of the roots was not increased by acid irrigation but rose with increasing soil depth, regardless of treatment. Liming increased root contents of Ca and Mg and reduced contents of Mn and Al. This effect was especially distinct in the humic layer and decreased with increasing soil depth. Even though the molar Ca/Al-ratio in the roots in the mineral soil was generally low (0.09–0.52), no evidence of Al toxicity could be found. The formation of Al complexes is discussed as a reason for this behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004206826290
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of acid irrigation and liming on nitrate reduction and nitrate content of Picea abies (L.) Karst. and Oxalis acetosella L. (1998)
    Springer
    Plant and soil 199 (1998), S. 59-70 
    Details
    ISSN: 1573-5036
    Keywords: acid irrigation ; liming ; nitrate leaching ; nitrate reductase ; Oxalis acetosella ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrate reductase activities (NRA) and nitrate concentration per unit biomass in Picea abies (L.) Karst. roots from four different soil horizons and in leaves and roots of the frequent field-layer species Oxalis acetosella L. were measured on six different irrigation and liming treatments within the Höglwald project, S-Bavaria, Germany. Liming increased and acid irrigation reduced soil nitrate availability when compared to control plots. Nitrate assimilation capacities of the respective plant compartments per unit of soil volume or ground area were calculated from the NRA per unit of biomass and from the biomass distribution on the various treatments. Mean NRA per unit of biomass in Picea abies roots ranged between 0.23 and 0.09 μmol NO 2 - g-1 d.w. h-1 without significant effects of soil horizon or treatment. Limed and non-limed treatments showed for Picea different root distributions within the soil profile, but root biomass per unit of ground area (295 to 220 g d.w. m-2) was not affected by the various treatments. Thus, nitrate assimilation capacity of Picea roots per unit of ground area ranged between 19.5 and 11.4 μmol NO 2 - m-2 h-1 without major treatment effects. In laminae of Oxalis acetosella mean NRA per unit of biomass ranged between 2.91 and 0.27 μmol NO 2 - g-1 d.w. h-1 and, in contrast to Picea abies, treatment effects were found with NRA on limed plots increased and on acid irrigated plots reduced when compared to control plots. Mean leaf biomass of Oxalis per unit of ground area ranged between 9.57 and 0.66 g d.w. m-2 and responded in a similar manner to the various treatments. Thus, for the Oxalis leaf NRA per unit of ground area (27.85 to 0.18 μmol NO2 m-2 h-1) a cumulative response to the variations in nitrate availability was found. The different responses of Picea abies and Oxalis acetosella to changes in soil nitrate availability are discussed with respect to their suitability to prevent soil nitrate leaching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004263223917
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  • 9
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    Cytomegalovirus remains latent in a common precursor of dendritic and myeloid cells (1998)
    National Academy of Sciences
    Details
    Publication Date: 1998-03-31
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Errors of the backextrapolation method in determination of the blood volume (1999)
    Institute of Physics
    Details
    Publication Date: 1999-01-01
    Print ISSN: 0031-9155
    Electronic ISSN: 1361-6560
    Topics: Biology , Medicine , Physics
    Published by Institute of Physics
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