The Planck SZ Cluster Catalog: Expected X-ray Properties

Surveys based on the Sunyaev-Zel'dovich (SZ) effect provide a fresh view of the galaxy cluster population, one that is complementary to X-ray surveys. To better understand the relation between these two kinds of survey, we construct an empirical cluster model using scaling relations constrained by current X-ray and SZ data. We apply our model to predict the X-ray properties of the Planck SZ Cluster Catalog (PCC) and compare them to existing X-ray cluster catalogs. We find that Planck should significantly extend the depth of the previous all-sky cluster survey, performed in the early 1990s by the ROSAT satellite, and should be particularly effective at finding hot, massive clusters (T > 6 keV) out to redshift unity. These are rare objects, and our findings suggest that Planck could increase the observational sample at z > 0.6 by an order of magnitude. This would open the way for detailed studies of massive clusters out to these higher redshifts. Specifically, we find that the majority of newly-detected Planck clusters should have X-ray fluxes 10^{-13} ergs/s/cm^2 < f_X[0.5-2 keV] < 10^{-12} ergs/s/cm^2, i.e., distributed over the decade in flux just below the ROSAT All Sky Survey limit. This is sufficiently bright for extensive X-ray follow-up campaigns. Once Planck finds these objects, XMM-Newton and \textit{Chandra} could measure temperatures to 10% for a sample of ~ 100 clusters in the range 0.5 < z < 1, a valuable increase in the number of massive clusters studied over this range.Comment: 8 pages, 7 figures submitted to A&A; accepted 29 May 201

An SZ/X-ray galaxy cluster model and the X-ray follow-up of the Planck clusters

Sunyaev-Zel'dovich (SZ) cluster surveys will become an important cosmological tool over next few years, and it will be essential to relate these new surveys to cluster surveys in other wavebands. We present an empirical model of cluster SZ and X-ray observables constructed to address this question and to motivate, dimension and guide X-ray follow-up of SZ surveys. As an example application of the model, we discuss potential XMM-Newton follow-up of Planck clusters.Comment: 4 pages, 5 figures. To appear in the proceedings of the XXXXIIIrd Rencontres de Morion

Ambipolar charge injection and transport in a single pentacene monolayer island

Electrons and holes are locally injected in a single pentacene monolayer island. The two-dimensional distribution and concentration of the injected carriers are measured by electrical force microscopy. In crystalline monolayer islands, both carriers are delocalized over the whole island. On disordered monolayer, carriers stay localized at their injection point. These results provide insight into the electronic properties, at the nanometer scale, of organic monolayers governing performances of organic transistors and molecular devices.Comment: To be published in Nano Letter

GABAergic compensation in connexin36 knock-out mice evident during low-magnesium seizure-like event activity

Gap junctions within the cerebral cortex may facilitate cortical seizure formation by their ability to synchronize electrical activity. To investigate this, one option is to compare wild-type (WT) animals with those lacking the gene for connexin36 (Cx36 KO); the protein that forms neuronal gap junctions between cortical inhibitory cells. However, genetically modified knock-out animals may exhibit compensatory effects; with the risk that observed differences between WT and Cx36 KO animals could be erroneously attributed to Cx36 gap junction effects. In this study we investigated the effect of GABAA-receptor modulation (augmentation with 16 μM etomidate and blockade with 100 μM picrotoxin) on low-magnesium seizure-like events (SLEs) in mouse cortical slices. In WT slices, picrotoxin enhanced both the amplitude (49% increase, p = 0.0006) and frequency (37% increase, p = 0.005) of SLEs; etomidate also enhanced SLE amplitude (18% increase, p = 0.003) but reduced event frequency (25% decrease, p < 0.0001). In Cx36 KO slices, the frequency effects of etomidate and picrotoxin were preserved, but the amplitude responses were abolished. Pre-treatment with the gap junction blocker mefloquin in WT slices did not significantly alter the drug responses, indicating that the reduction in amplitude seen in the Cx36 KO mice was not primarily mediated by their lack of interneuronal gap junctions, but was rather due to pre-existing compensatory changes in these animals. Conclusions from studies comparing seizure characteristics between WT and Cx36 KO mice must be viewed with a degree of caution because of the possible confounding effect of compensatory neurophysiological changes in the genetically modified animals

Assessing the role of dispersed floralresources for managed bees in providingsupporting ecosystem services for croppollination

Most pollination ecosystem services studies have focussed on wild pollinators and their dependence on natural floral resources adjacent to crop fields. However, managed pollinators depend on a mixture of floral resources that are spatially separated from the crop field. Here, we consider the supporting role these resources play as an ecosystem services provider to quantify the use and availability of floral resources, and to estimate their relative contribution to support pollination services of managed honeybees. Beekeepers supplying pollination services to the Western Cape deciduous fruit industry were interviewed to obtain information on their use of floral resources. For 120 apiary sites, we also analysed floral resources within a two km radius of each site based on geographic data. The relative availability of floral resources at sites was compared to regional availability. The relative contribution of floral resources-types to sustain managed honeybees was estimated. Beekeepers showed a strong preference for eucalypts and canola. Beekeepers selectively placed more hives at sites with eucalypt and canola and less with natural vegetation. However, at the landscape-scale, eucalypt was the least available resource, whereas natural vegetation was most common. Based on analysis of apiary sites, we estimated that 700,818 ha of natural vegetation, 73,910 ha of canola fields, and 10,485 ha of eucalypt are used to support the managed honeybee industry in the Western Cape. Whereas the Cape managed honeybee system uses a bee native to the region, alien plant species appear disproportionately important among the floral resources being exploited. We suggest that an integrated approach, including evidence from interview and landscape data, and fine-scale biological data is needed to study floral resources supporting managed honeybees