Generalized, switch-like competitive heterodimerization networks

High-dimensional switches have been proposed as a way to model cellular differentiation, particularly in the context of basic Helix-Loop-Helix (bHLH) competitive heterodimerization networks. A previous study derived a simple rule showing how many elements can be co-expressed, depending on the rate of competition within the network. A limitation to that rule, however, is that many biochemical parameters were considered to be identical. Here, we derive a generalized rule. This in turns allows one to study more ways in which these networks could be regulated, linking intrinsic cellular differentiation determinants to extra-cellular cues

Contribution of simulation and gaming to natural resource management issues: An introduction

Nowadays, computer-mediated simulations and games are widely used in the field of natural resource management (NRM). They have proved to be useful for various purposes such as supporting decisionmaking processes and training. First, the specificities of the NRM research field are highlighted. Then, based on the analysis of the articles presented in this special issue of Simulation & Gaming, some key features related to the implementation of gaming in such a context are introduced. Finally, after reviewing the benefits of using simulation games in NRM, the authors stress the ethical issue of changing social relationships among stakeholders by playing a game with some of themGESTION DE L'ENVIRONNEMENT;RESSOURCE NATURELLE;SIMULATION;SOCIOLOGIE;JEU DE ROLE;BENEFITS;CONTEXT;COLLECTIVE POLICY DESIGN;DECISION MAKING;ETHICAL ISSUES;IMPLEMENTATION;NATURAL RESOURCE MANAGEMENT (NRM);SIMULATION GAMES;SOCIAL EMPOWERMENT;SOCIAL RELATIONSHIPS;SOCIOECOLOGICAL SYSTEMS;STAKEHOLDERS

Large-scale wind-tunnel tests of descent performance of an airplane model with a tilt wing and differential propeller thrust

Wind tunnel tests of wing stall, performance, and longitudinal stability & control of large model v/stol tilt wing transport aircraf

Intersubband magnetophonon resonances in quantum cascade structures

We report on our magnetotransport measurements of GaAs/GaAlAs quantum cascade structures in a magnetic field of up to 62 T. We observe novel quantum oscillations in tunneling current that are periodic in reciprocal magnetic field. We explain these oscillations as intersubband magnetophonon resonance due to electron relaxation by emission of either single optical or acoustic phonons. Our work also provides a non-optical in situ measurement of intersubband separations in quantum cascade structures.Comment: 5 pages, 4 figure

Cooling of the Cassiopeia A neutron star and the effect of diffusive nuclear burning

The study of how neutron stars cool over time can provide invaluable insights into fundamental physics such as the nuclear equation of state and superconductivity and superfluidity. A critical relation in neutron star cooling is the one between observed surface temperature and interior temperature. This relation is determined by the composition of the neutron star envelope and can be influenced by the process of diffusive nuclear burning (DNB). We calculate models of envelopes that include DNB and find that DNB can lead to a rapidly changing envelope composition which can be relevant for understanding the long-term cooling behavior of neutron stars. We also report on analysis of the latest temperature measurements of the young neutron star in the Cassiopeia A supernova remnant. The 13 Chandra observations over 18 years show that the neutron star's temperature is decreasing at a rate of 2-3 percent per decade, and this rapid cooling can be explained by the presence of a proton superconductor and neutron superfluid in the core of the star.Comment: 7 pages, 7 figures; to appear in the AIP Conference Proceedings of the Xiamen-CUSTIPEN Workshop on the EOS of Dense Neutron-Rich Matter in the Era of Gravitational Wave Astronomy (January 3-7, 2019, Xiamen, China

Thermal Evolution and Light Curves of Young Bare Strange Stars

The cooling of a young bare strange star is studied numerically by solving the equations of energy conservation and heat transport for both normal and superconducting strange quark matter inside the star. We show that the thermal luminosity from the strange star surface, due to both photon emission and e+e- pair production, may be orders of magnitude higher than the Eddington limit, for about one day for normal quark matter but possibly for up to a hundred years for superconducting quark matter, while the maximum of the photon spectrum is in hard X-rays with a mean energy of ~ 100 keV or even more. This differs both qualitatively and quantitatively from the photon emission from young neutron stars and provides a definite observational signature for bare strange stars. It is shown that the energy gap of superconducting strange quark matter may be estimated from the light curves if it is in the range from ~ 0.5 MeV to a few MeV.Comment: Ref [10] added and abstract shortened. 4 pages, 3 figures, revtex4. To be published in Phys. Rev. Letter

Constraints on the distribution of absorption in the X-ray selected AGN population found in the 13H XMM-Newton/Chandra deep field

We present an analysis of the X-ray properties of sources detected in the 13H XMM-Newton deep (200ks) field. In order to constrain the absorbed AGN population, we use extensive Monte Carlo simulations to directly compare the X-ray colours of observed sources with those predicted by several model distributions. We have tested the simplest form of the AGN unified scheme, whereby the intrinsic XLF of absorbed AGN is set to be the same as that of their unabsorbed brethren, coupled with various model distributions of absorption. The best fitting of these models sets the fraction of AGN with absorbing column NH, proportional to (logNH)^8. We have also tested two extensions to the unified scheme: an evolving absorption scenario, and a luminosity dependent model distribution. Both of these provide poorer matches to the observed X-ray colour distributions than the best fitting simple unified model. We find that a luminosity dependent density evolution XLF reproduces poorly the 0.5-2 keV source counts seen in the 13H field. Field to field variations could be the cause of this disparity. Computing the simulated X-ray colours with a simple absorbed power-law + reflection spectral model is found to over-predict, by a factor of two, the fraction of hard sources that are completely absorbed below 0.5 keV, implying that an additional source of soft-band flux must be present for a number of the absorbed sources. Finally, we show that around 40% of the 13H sample are expected to be AGN with NH>10^22 cm^-2.Comment: 13 pages, 9 figures, Accepted for publication in MNRA

Extremely red objects in the UKIDSS Ultra Deep Survey Early Data Release

We construct a sample of extremely red objects (EROs) within the UKIDSS Ultra Deep Survey by combining the Early Data Release with optical data from the Subaru/XMM–Newton Deep Field. We find a total of 3715 objects over 2013 arcmin2 with R−K > 5.3 and K≤ 20.3, which is a higher surface density than found by previous studies. This is partly due to our ability to use a small aperture in which to measure colours, but is also the result of a genuine overdensity of objects compared to other fields. We separate our sample into passively evolving and dusty star-forming galaxies using their RJK colours and investigate their radio properties using a deep radio map. The dusty population has a higher fraction of individually detected radio sources and a higher mean radio flux density among the undetected objects, but the passive population has a higher fraction of bright radio sources, suggesting that active galactic nuclei are more prevalent among the passive ERO population