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  • Articles  (43)
  • Articles: DFG German National Licenses  (43)
  • 2015-2019
  • 2005-2009  (43)
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  • Articles  (43)
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  • 1
    Electronic Resource
    Electronic Resource
    “How Local Is Local?”—A Review of Practical and Conceptual Issues in the Genetics of Restoration (2005)
    Oxford, UK; Malden, USA : Blackwell Science Inc
    Restoration ecology 13 (2005), S. 0 
    Details
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In plant conservation, restoration (the augmentation or reestablishment of an extinct population or community) is a valuable tool to mitigate the loss of habitat. However, restoration efforts can result in the introduction of novel genes and genotypes into populations when plant materials used are not of local origin. This movement is potentially important because many plant species are subdivided into populations that are adapted to local environmental conditions. Here we focus on genetic concerns arising from ongoing restoration efforts, where often little is known about “How local is local?” (i.e., the geographic or environmental scale over which plant species are adapted). We review the major issues regarding gene flow and local adaptation in the restoration of natural plant populations. Finally, we offer some practical, commonsense guidelines for the consideration of genetic structure when restoring natural plant populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1526-100X.2005.00058.x
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  • 2
    Electronic Resource
    Electronic Resource
    Current trends of soil organic carbon in English arable soils (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 21 (2005), S. 0 
    Details
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. A model of the impact of land management changes upon soil organic carbon (SOC) was constructed, and the total amount of topsoil organic carbon was estimated for the arable area of England from 1940 to 2000. The largest influence on the overall mean SOC in arable topsoils proved to be a decline in the area of both permanent and temporary grassland. SOC declined over a prolonged period (60 years), but has now reached a plateau. Modelling changes in mean values enabled a statistical evaluation to be made between a measured decline in the number of sites with ‘high’ SOC levels between 1980 and 1995, and the decline predicted by the model. The SOC content of arable soils in England was measured at National Soil Inventory sites twice in recent decades: in 1980 and 1995. The proportion of fine textured soils in the lowest SOC class (〈2.3%) rose from just over 40% to about 50% over the same period. There was a significant difference between the observed values of 1995 and those expected from modelling the decline from 1980 values, in the category of ‘low SOC’ fine textured soils. The variation in the fine textured soils represents a significant and widespread decline in topsoil organic carbon concentrations, which was greater than the underlying long-term trend.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1475-2743.2005.tb00124.x
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  • 3
    Electronic Resource
    Electronic Resource
    Structural differences between bulk and rhizosphere soil (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    European journal of soil science 56 (2005), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The physical characteristics of the soil at the root–soil interface are crucial because they determine both physical aspects of root function such as water and nutrient uptake and the microbial activity that is most relevant to root growth. Because of this we have studied how root activity modifies the structure and water retention characteristic of soil adjacent to the root for maize, wheat and barley. These plants were grown in pots for a 6-week growth period, then the soil adjacent to the root (rhizosphere soil) and bulk soil aggregates were harvested. These soil aggregates were then saturated and equilibrated at matric potentials between −600 kPa and saturation, and the water retention characteristics were measured. From subsamples of these aggregates, thin sections were made and the porosity and pore-size distributions were studied with image analysis. Both image analysis and estimates of aggregated density showed that the rhizosphere soil and bulk soil had similar porosities. Growing different plants had a small but significant effect on the porosity of the soil aggregates. Image analysis showed that for all the plant species the structure of the rhizosphere soil was different to that of the bulk soil. The rhizosphere soil contained more larger pores. For maize and barley, water retention characteristics indicated that the rhizosphere soil tended to be drier at a given matric potential than bulk soil. This effect was particularly marked at greater matric potentials. The difference between the water retention characteristics of the bulk and rhizosphere soil for wheat was small. We compare the water retention characteristics with the data on pore-size distribution from image analysis. We suggest that differences in wetting angle and pore connectivity might partly explain the differences in water retention characteristic that we observed. The impact of differences between the water retention properties of the rhizosphere and bulk soil is discussed in terms of the likely impact on root growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2389.2004.00670.x
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  • 4
    Electronic Resource
    Electronic Resource
    THE FISCAL CHALLENGE OF COMPETITIVE MARKETS (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Economic affairs 25 (2005), S. 0 
    Details
    ISSN: 1468-0270
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: Competition maximises consumer satisfaction but creates a financial problem for enterprises. When prices are competed down to just cover marginal costs, part of the value added by the enterprise is externalised. Government has not been efficient at recycling that value back into the economy, which is why infrastructure is severely underfunded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1468-0270.2005.00534.x
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  • 5
    Electronic Resource
    Electronic Resource
    Distributed Generation Capacity Evaluation Using Combined Genetic Algorithm and OPF (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of emerging electric power systems 8.2007, 2, art7 
    Details
    ISSN: 1553-779X
    Source: Berkeley Electronic Press Academic Journals
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A range of techniques has been proposed to define the optimal locations and capacities of distributed generation (DG) as a means of ensuring that the maximum amount of DG can be connected to existing and future networks. However, there are limitations inherent in these methods, not least in finding the best combination of sites for connecting a predefined number of DGs. Here, a method combining optimal power flow and genetic algorithms aims to meet this requirement. Its use would be in enabling Distribution Network Operators to search a network for the best sites and capacities available to strategically connect a defined number of DGs among a large number of potential combinations. Some applications of the proposed methodology confirmed its effectiveness in sitting and sizing an assigned number of DG units.
    Type of Medium: Electronic Resource
    URL: http://www.bepress.com/ijeeps/vol8/iss2/art7
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  • 6
    Electronic Resource
    Electronic Resource
    Spatial and Temporal Resolution in Data-Driven Process Modeling of an Integrated Newsprint Mill (2007)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Chemical product and process modeling 2 (2007), S. 13 
    Details
    ISSN: 1934-2659
    Source: Berkeley Electronic Press Academic Journals
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Like many globalized industries, the pulp and paper sector finds itself with an increasingly demanding clientele, who continually expect a better and cheaper product. An important design strategy being employed to address this objective is through an analysis of the vast quantity of process and product data accumulated in plant-wide data historians, in order to improve operations. Mill processes are multivariate, meaning that the interactions between the variables are as important as the variables themselves. Process relationships must therefore be modeled as a group, using an appropriate simulation technique like Multivariate Analysis (MVA), with suitable data pre-processing to account for process upsets and other disturbances. In a previous paper, using an Eastern Canadian newsprint mill as an industrial case study, we showed that it was possible to find statistically significant correlations between wood chip refiner operation, intermediate pulp quality, and final paper quality using data-driven models. This was true even though some important process parameters went unmeasured, process lags changed with time, and the operation of key equipment items changed gradually with use. The present study compares the use of different timescales and combinations of unit operations to determine which ones yield the best MVA simulations. Because plant operating data were used, and experimental design was not practical, it is possible that some of the correlations found could be attributable to coincidence. We therefore added and removed variables and time periods to explore the validity of the models. The best MVA models were obtained by using a shorter (1-hour) data timescale, although use of a weighted-average filter helped to bridge the gap between these faster readings and the slower paper quality trends.
    Type of Medium: Electronic Resource
    URL: http://www.bepress.com/cppm/vol2/iss1/13
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  • 7
    Electronic Resource
    Electronic Resource
    The Effect of the Nonprofit Motive on Hospital Competitive Behavior (2005)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Contributions to economic analysis & policy 4.2005, 1, art3 
    Details
    ISSN: 1538-0645
    Source: Berkeley Electronic Press Academic Journals
    Topics: Economics
    Notes: In this paper, we employ three simple theoretical models of nonprofit hospitals to investigate equilibrium behavior when hospitals compete. Utilizing a differentiated Bertrand model, we examine how prices, quantity of patients served, service to the uninsured, and quality of care are affected as nonprofits place more weight on profit maximization. We find that the specification of the nonprofit motive greatly impacts the results. When the nonprofit motive is maximizing output, prices rise for both hospitals as the nonprofit moves away from its nonprofit motive. However, if the nonprofit cares about serving the uninsured, prices in the market fall. Finally, when hospitals compete on price and quality, more emphasis on profits results in an increase in price at the for-profit hospital and a decrease in price at the nonprofit hospital. These results suggest that the importance of the nonprofit motive has been underestimated and should be further investigated.
    Type of Medium: Electronic Resource
    URL: http://www.bepress.com/bejeap/contributions/vol4/iss1/art3
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  • 8
    Electronic Resource
    Electronic Resource
    Investigating Nonlinearity: A Note on the Estimation of Hamilton's Random Field Regression Model (2005)
    Cambridge, Mass. : Berkeley Electronic Press (now: De Gruyter)
    Studies in nonlinear dynamics and econometrics 9.2005, 3, art2 
    Details
    ISSN: 1081-1826
    Source: Berkeley Electronic Press Academic Journals
    Topics: Mathematics , Economics
    Notes: In this paper we give an account of the approach to nonlinear econometric modelling proposed by Hamilton (2001) and briefly describe some of the methods of nonlinear optimization that may be used in the Gauss computer program provided by Hamilton for the implementation of his methodology. The performance of this program is investigated using data relating to Hamilton's example concerning the US Phillips curve, two versions of the Gauss software, and a range of alternative numerical optimization options and values for the Gauss parameter _oprteps. The impact of changes in initial parameter estimates and the use of pairs of optimization algorithms are also briefly examined. Finally, the effects of changes in the sample data on the results produced by Hamilton's procedure are explored. The results presented suggest some clear conclusions, which will be of value to those contemplating working with Hamilton's new method.
    Type of Medium: Electronic Resource
    URL: http://www.bepress.com/snde/vol9/iss3/art2
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  • 9
    Electronic Resource
    Electronic Resource
    SIGNALING IN THE ARBUSCULAR MYCORRHIZAL SYMBIOSIS (2005)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 59 (2005), S. 19-42 
    Details
    ISSN: 0066-4227
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Many microorganisms form symbioses with plants that range, on a continuous scale, from parasitic to mutualistic. Among these, the most widespread mutualistic symbiosis is the arbuscular mycorrhiza, formed between arbuscular mycorrhizal (AM) fungi and vascular flowering plants. These associations occur in terrestrial ecosystems throughout the world and have a global impact on plant phosphorus nutrition. The arbuscular mycorrhiza is an endosymbiosis in which the fungus inhabits the root cortical cells and obtains carbon provided by the plant while it transfers mineral nutrients from the soil to the cortical cells. Development of the symbiosis involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells. The aim of this review is to explore the current understanding of the signals and signaling pathways used by the symbionts for the development of the AM symbiosis. Although the signal molecules used for initial communication are not yet known, recent studies point to their existence. Within the plant, there is evidence of arbuscular mycorrhiza-specific signals and of systemic signaling that influences phosphate-starvation responses and root development. The landmark cloning of three plant signaling proteins required for the development of the symbiosis has provided the first insights into a signaling pathway that is used by AM fungi and by rhizobia for their symbiotic associations with legumes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.micro.58.030603.123749
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  • 10
    Electronic Resource
    Electronic Resource
    MECHANISMS OF DIGESTION AND ABSORPTION OF DIETARY VITAMIN A * (2005)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nutrition 25 (2005), S. 87-103 
    Details
    ISSN: 0199-9885
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Mechanisms involved in the digestion and absorption of dietary vitamin A require the participation of several proteins. Dietary retinyl esters are hydrolyzed in the intestine by the pancreatic enzyme, pancreatic triglyceride lipase, and intestinal brush border enzyme, phospholipase B. Unesterified retinol taken up by the enterocyte is complexed with cellular retinol-binding protein type 2 and the complex serves as a substrate for reesterification of the retinol by the enzyme lecithin:retinol acyltransferase (LRAT). The retinyl esters are then incorporated into chylomicrons, intestinal lipoproteins containing other dietary lipids, such as triglycerides, phospholipids, and free and esterified cholesterol, and apolipoprotein B. Chylomicrons containing newly absorbed retinyl esters are then secreted into the lymph. Although under normal dietary conditions much of the dietary vitamin A is absorbed via the chylomicron/lymphatic route, it is also clear that under some circumstances there is substantial absorption of unesterified retinol via the portal route. Evidence supports the idea that the cellular uptake and efflux of unesterified retinol by enterocytes is mediated by lipid transporters, but the exact number, identity, and role of these proteins is not known and is an active area of research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.nutr.25.050304.092614
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