Coordination of Decisions in a Spatial Agent Model

For a binary choice problem, the spatial coordination of decisions in an agent community is investigated both analytically and by means of stochastic computer simulations. The individual decisions are based on different local information generated by the agents with a finite lifetime and disseminated in the system with a finite velocity. We derive critical parameters for the emergence of minorities and majorities of agents making opposite decisions and investigate their spatial organization. We find that dependent on two essential parameters describing the local impact and the spatial dissemination of information, either a definite stable minority/majority relation (single-attractor regime) or a broad range of possible values (multi-attractor regime) occurs. In the latter case, the outcome of the decision process becomes rather diverse and hard to predict, both with respect to the share of the majority and their spatial distribution. We further investigate how a dissemination of information on different time scales affects the outcome of the decision process. We find that a more ``efficient'' information exchange within a subpopulation provides a suitable way to stabilize their majority status and to reduce ``diversity'' and uncertainty in the decision process.Comment: submitted for publication in Physica A (31 pages incl. 17 multi-part figures

Establishing species-specific sexing markers suitable for non-invasive samples of species lacking genomic resources: an example using the highly endangered common hamster Cricetus cricetus

Here we present an approach to establish species-specific genetic markers for sex identification suitable for non-invasive samples. Such markers are not yet available for the endangered common hamster (Cricetus cricetus) because of the lack of genomic resources. Using Y chromosome conserved anchored tagged sequences (YCATS) exonic primers, we obtained Y-chromosomal sequences from hamsters and sympatric rodent species. From this, we designed hamster-specific primers targeting two short Y-chromosomal intron fragments and included them in microsatellite multiplex reactions, using autosomal loci also as amplification controls. The method yielded highly consistent results. The approach can be easily applied to development of sex markers in species for which there are no genome sequences available and thus aid conservation genetics efforts

Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

Using Suzaku and the Rossi X-ray Timing Explorer, we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard low states. Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the focused wind from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating. These latter spectra are crucial for revealing the ionized absorption due to the secondary's focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c^2. All three models also agree that the known spectral break at 10\,keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, {thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is >40 GM/c^2.Comment: 22 pages, 16 figures. Uses emulateapj style. Final three tables inserted as a figure to avoid issues with astro-ph's version of latex mangling the use of lscape. To be published in the Astrophysical Journal, January, 201

Emotional Strategies as Catalysts for Cooperation in Signed Networks

The evolution of unconditional cooperation is one of the fundamental problems in science. A new solution is proposed to solve this puzzle. We treat this issue with an evolutionary model in which agents play the Prisoner's Dilemma on signed networks. The topology is allowed to co-evolve with relational signs as well as with agent strategies. We introduce a strategy that is conditional on the emotional content embedded in network signs. We show that this strategy acts as a catalyst and creates favorable conditions for the spread of unconditional cooperation. In line with the literature, we found evidence that the evolution of cooperation most likely occurs in networks with relatively high chances of rewiring and with low likelihood of strategy adoption. While a low likelihood of rewiring enhances cooperation, a very high likelihood seems to limit its diffusion. Furthermore, unlike in non-signed networks, cooperation becomes more prevalent in denser topologies.Comment: 24 pages, Accepted for publication in Advances in Complex System

X-ray continuum variability of MCG-6-30-15

This paper presents a comprehensive examination of the X-ray continuum variability of the bright Seyfert 1 galaxy MCG-6-30-15. The source clearly shows the strong, linear correlation between rms variability amplitude and flux first seen in Galactic X-ray binaries. The high frequency power spectral density (PSD) of MCG-6-30-15 is examined in detail using a Monte Carlo fitting procedure and is found to be well represented by a steep power-law at high frequencies (with a power-law index alpha ~ 2.5), breaking to a flatter slope (alpha ~ 1) below f_br ~ 0.6 - 2.0 x 10^-4 Hz, consistent with the previous results of Uttley, McHardy & Papadakis. The slope of the power spectrum above the break is energy dependent, with the higher energies showing a flatter PSD. At low frequencies the variations between different energy bands are highly coherent while at high frequencies the coherence is significantly reduced. Time lags are detected between energy bands, with the soft variations leading the hard. The magnitude of the lag is small (<200 s for the frequencies observed) and is most likely frequency dependent. These properties are remarkably similar to the temporal properties of the Galactic black hole candidate Cygnus X-1. The characteristic timescales in these two types of source differ by ~10^5; assuming that these timescales scale linearly with black hole mass then suggests a black hole mass ~10^6 M_sun for MCG-6-30-15. We speculate that the timing properties of MCG-6-30-15 may be analogous to those of Cyg X-1 in its high/soft state and discuss a simple phenomenological model, originally developed to explain the timing properties of Cyg X-1, that can explain many of the observed properties of MCG-6-30-15.Comment: 19 pages, 24 figures, accepted for publication in MNRA

Marginale Gruppen auf dem Wohnungsmarkt: das Beispiel Bremen

"In diesem Arbeitspapier geht es um die räumliche Verteilung sozial benachteiligter Gruppen. Dabei werden unter anderem Wechselwirkungen zwischen Sozial- und Wohnungspolitik aufgezeigt und sowohl Quer- wie Längsschnittanalysen angewendet. Die Frage nach dem Ausmaß räumlicher Segregation in Bremen wird in zwei Schritten bearbeitet: Zunächst wird die Lage benachteiligter Gruppen auf dem Wohnungsmarkt in Bremen - etwa Anteil an den Sozialwohnungen, verfügbare Wohnfläche, räumliche Verteilung im Stadtgebiet - auf der Grundlage aggregierter Querschnittsdaten untersucht. Dann wird die Verdrängungsthese anhand individueller Längsschnittdaten überprüft.