Constraint satisfaction problems for reducts of homogeneous graphs

For n >= 3, let (Hn, E) denote the n-th Henson graph, i.e., the unique countable homogeneous graph with exactly those finite graphs as induced subgraphs that do not embed the complete graph on n vertices. We show that for all structures Gamma with domain Hn whose relations are first-order definable in (Hn, E) the constraint satisfaction problem for Gamma is either in P or is NP-complete. We moreover show a similar complexity dichotomy for all structures whose relations are first-order definable in a homogeneous graph whose reflexive closure is an equivalence relation. Together with earlier results, in particular for the random graph, this completes the complexity classification of constraint satisfaction problems of structures first-order definable in countably infinite homogeneous graphs: all such problems are either in P or NP-complete

The fine- and generative spectra of varieties of monounary algebras

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Neural Cell Response to Nanostructured Biosensor Surfaces

AbstractIn our work we investigate the interaction of cells and nanotextured surfaces as a model of implanted device surface and living tissue interaction. We developed a maskless nanostructuring method, which can be integrated into our neural biosensor fabrication process. Morphology of the fabricated nanograss was characterised using SEM. The nanorods are 520-800nm in height and their density is 18-70/μm2. Electrochemical impedance spectroscopy and contact angles of different surfaces were measured. The specific surface area is 30 times larger than the reference. The contact-angle can be tuned. The samples will be tested in viability and adhesion assays using neural cell cultures

dUTPase based switch controls transfer of virulence genes in order to preserve integrity of the transferred mobile genetic elements

dUTPases ubiquitously regulate cellular dUTP levels to preserve genome integrity. Recently, several other cellular processes were reported to be controlled by dUTPases including the horizontal transfer of Staphylococcus aureus pathogenicity islands (SaPI). SaPIs are mobil genetic elements that encode virulence enhancing factors e.g. toxins. Here, phage dUTPases were proposed to counteract the repressor protein (Stl) and promote SaPI excision and transfer. A G protein-like mechanism was proposed which is unexpected in light of the kinetic mechanism of dUTPase. Here we investigate the molecular mechanism of SaPI transfer regulation, using numerous dUTPase variants and a wide range of in vitro methods (steady-state and transient kinetics, VIS and fluorescence spectroscopy, EMSA, quartz crystal microbalance, X-ray crystallography). Our results unambiguously show that Stl inhibits the enzymatic activity of dUTPase in the nM concentration range and dUTP strongly inhibits the dUTPase: Stl complexation. These results identify Stl as a highly potent dUTPase inhibitor protein and disprove the G protein-like mechanism. Importantly, our results clearly show that the dUTPase:dUTP complex is inaccessible to the Stl repressor. Unlike in small GTPases, hydrolysis of the substrate nucleoside triphosphate (dUTP in this case) is required prior to the interaction with the partner (Stl repressor in this case). We propose that dUTPase can efficiently interact with Stl and induce SaPI excision only if the cellular dUTP level is low (i.e. when dUTPase resides mainly in the apo enzyme form) while high dUTP levels would inhibit SaPI transfer. This mechanism may serve the preservation of the integrity of the transferred SaPI genes and links the well-known metabolic role of dUTPases to their newly revealed regulatory function in spread of virulence factors

Impacts of offshore oil spill accidents on island bird communities: A test run study around Orkney and Svalbard archipelagos

The sea area around the Orkney archipelago, Scotland is subjected to substantial maritime shipping activities. By contract, the Svalbard archipelago, Norway currently has a rather low marine traffic profile. Future projections, however, indicate that the Trans-Arctic route might change the whole transportation picture and Svalbard may be at the centre of maritime activities. Both archipelagos have sensitive environmental resources at sea and inland, including bird communities. There are, for instance, 13 Red Listed species present in Orkney and 2 in Svalbard. In this regard, it is important to address oil spill risks along existing and projected shipping routes. Hypothetical spills were simulated in twelve scenarios for both the Orkney and Svalbard archipelagos with the OpenDrift open-source software. The results indicate risks to seabird communities. For Orkney, the spills resulted in the most extensive contamination of the sea and land environments in autumn. For Svalbard, autumn spills on the contrary presented the lowest risk to seabirds. Based on the simulations, we recommend increased caution for shipping activities in the problematic seasons, improved local readiness for ship accidents and sufficient preincident planning

The future climate characteristics of the Carpathian Basin based on a regional climate model mini-ensemble

Four regional climate models (RCMs) were adapted in Hungary for the dynamical downscaling of the global climate projections over the Carpathian Basin: (i) the ALADIN-Climate model developed by Météo France on the basis of the ALADIN short-range modelling system; (ii) the PRECIS model available from the UK Met Office Hadley Centre; (iii) the RegCM model originally developed at the US National Center for Atmospheric Research, is maintained at the International Centre for Theoretical Physics in Trieste; and (iv) the REMO model developed by the Max Planck Institute for Meteorology in Hamburg. The RCMs are different in terms of dynamical model formulation, physical parameterisations; moreover, in the completed simulations they use different spatial resolutions, integration domains and lateral boundary conditions for the scenario experiments. Therefore, the results of the four RCMs can be considered as a small ensemble providing information about various kinds of uncertainties in the future projections over the target area, i.e., Hungary. After the validation of the temperature and precipitation patterns against measurements, mean changes and some extreme characteristics of these patterns (including their statistical significance) have been assessed focusing on the periods of 2021–2050 and 2071–2100 relative to the 1961–1990 model reference period. The ensemble evaluation indicates that the temperature-related changes of the different RCMs are in good agreement over the Carpathian Basin and these tendencies manifest in the general warming conditions. The precipitation changes cannot be identified so clearly: seasonally large differences can be recognised among the projections and between the two periods. An overview is given about the results of the mini-ensemble and special emphasis is put on estimating the uncertainties in the simulations for Hungary