Evolutionary Dynamics of Seed Size and Seedling Competitive Ability

We present a model for the evolutionary dynamics of seed size when seedlings from large seeds are better competitors than seedling from small seeds and there is a trade-off between seed size and seed number. We first consider two limiting cases where seed size either has no effect on the competitive ability of seedlings, or where seedlings from larger seeds always win from seedlings from smaller seeds if together from the same germination site. In the first case there is a single evolutionary optimal seed size excluding all other, whereas in the second case there is an evolutionary stable seed polymorphism with a continuous variation of seed sizes where plants with small (but numerous seeds) survive by exploiting sites that by chance remain unoccupied by plants with larger (but less numerous) seeds. We investigate how these two cases connect to one another via intermediate levels of competitive asymmetry. We find that strong competitive asymmetry and high resource levels favor coexistence of plants with different seed sizes when seed and seedling survival is moderately low but large seeds have a substantial competitive advantage over small seeds. Assuming mutation-limited evolution and assuming that single mutations have only a small phenotypic effect, an initially monomorphic population with a single seed size will reach the final evolutionarily stable polymorphic state through a series of discrete evolutionary branching events. At each branching event, a given lineage already present in the population divides into two daughter lines, each with its own seed size. If precompetitive seed and seedling survival is high for small and large seeds alike, evolutionary branching may be followed by extinction of one or more lineages (including mass-extinction), and thus not necessarily gives rise to evolutionarily stable seed polymorphism. Various results presented here are model-independent and point the way to a more general evolutionarily bifurcation theory describing how the number and stability properties of evolutionary equilibria can change as a consequence of changes in model parameters

Demystifying smart grids - Different concepts and the connection with smart metering

The topic of Smart Grids is widely debated. It seems, however, that in the international arena a broad range of quite different concepts are referred to with this notion. Further, there is much confusion about the relation between Smart Grids and smart metering. This paper aims at structuring the discussion on Smart Grids by distinguishing three fundamentally different Smart Grid concepts and introducing corresponding terminology. These concepts serve different goals, affect different actors in different ways and require different technological solutions. Finally, smart metering is embedded into the developed framework

A market-based investigation of large-scale renewable energy integration in northwestern Europe

A high increase in the installed capacities of Renewable Energy Sources (RES) is expected by 2020 and beyond in Europe, and power systems planners and regulators have to make sure that the power systems are designed and operated to make optimal use of the potential of these clean energy sources. This paper investigates the consequences of integrating large-scale solar and wind power in the future Northwestern European power system. A zonal market model is used, where unit commitment and economic dispatch simulations for a given development scenario of load and generation, including wind power and solar power time series and inter-zonal transmission constraints, are with hourly resolution. The ability of the power system to absorb the available "green" energy is assessed. Moreover, factors that can hamper or improve the RES integration are identified by performing a sensitivity analysis on a subset of the scenario attributes

Discovery and Differential Processing of HLA Class II-Restricted Minor Histocompatibility Antigen LB-PIP4K2A-1S and Its Allelic Variant by Asparagine Endopeptidase

Minor histocompatibility antigens are the main targets of donor-derived T-cells after allogeneic stem cell transplantation. Identification of these antigens and understanding their biology are a key requisite for more insight into how graft vs. leukemia effect and graft vs. host disease could be separated. We here identified four new HLA class II-restricted minor histocompatibility antigens using whole genome association scanning. For one of the new antigens, i.e., LB-PIP4K2A-1S, we measured strong T-cell recognition of the donor variant PIP4K2A-1N when pulsed as exogenous peptide, while the endogenously expressed variant in donor EBV-B cells was not recognized. We showed that lack of T-cell recognition was caused by intracellular cleavage by a protease named asparagine endopeptidase (AEP). Furthermore, microarray gene expression analysis showed that PIP4K2A and AEP are both ubiquitously expressed in a wide variety of healthy tissues, but that expression levels of AEP were lower in primary acute myeloid leukemia (AML). In line with that, we confirmed low activity of AEP in AML cells and demonstrated that HLA-DRB1*03:01 positive primary AML expressing LB-PIP4K2A-1S or its donor variant PIP4K2A-1N were both recognized by specific T-cells. In conclusion, LB-PIP4K2A-1S not only represents a novel minor histocompatibility antigen but also provides evidence that donor T-cells after allogeneic stem cell transplantation can target the autologous allelic variant as leukemia-associated antigen. Furthermore, it demonstrates that endopeptidases can play a role in cell type-specific intracellular processing and presentation of HLA class II-restricted antigens, which may be explored in future immunotherapy of AML

Directional Derivative-Based Method for Quasi-Stationary Voltage Support Analysis of Single-Infeed VSC-HVDC units

This study presents an investigation of the impact of the quasi-stationary voltage support provided by a voltage source converter (VSC) connected to a single point of a power system. Based on the directional derivative concept, an analytical method is developed to quantify the sensitivities of the AC bus voltage with respect to the VSC reactive power control modes. Based on a real case study, it is shown that the method applies to VSC units that are part of VSC-HVDC systems, which can operate in a point-to-point or multi-terminal configuration. Time-domain simulations are performed to verify the findings from the application of the analytical method on a reduced size power system.</p

AFLP markers for the R-gene in the flea beetle, Phyllotreta nemorum, conferring resistance to defenses in Barbarea vulgaris

A so-called R-gene renders the yellow-striped flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) resistant to the defenses of the yellow rocket Barbarea vulgaris R.Br. (Brassicacea) and enables it to use it as a host plant in Denmark. In this study, genetic markers for an autosomal R-gene, inherited as a single, dominant locus in flea beetles from the Danish locality "Kværkeby" are described, and a genetic linkage map around this particular R-gene is constructed, using the technique of AFLP (Amplified Fragment Length Polymorphism

Assessing Communities of Practice in health policy : A conceptual framework as a first step towards empirical research

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