50 research outputs found
The Promoter of Rv0560c Is Induced by Salicylate and Structurally-Related Compounds in <i>Mycobacterium tuberculosis</i>
No full textPMCID: PMC3317779This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Mycobacterium tuberculosis ClpP Proteases Are Co-transcribed but Exhibit Different Substrate Specificities
No full textPMCID: PMC3613350This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
John Gay's the beggar's opera: early eighteenth-century responses in the arts to cultural, sociological and political issues in London life
No full textDiffering responses in art media to these contemporary issues of London life are explored, taking John Gay's the Beggar's Opera as the focal point for discussion. Initially, a general survey is made of Gay's role as cultural, social and moral critic. Comparison with George Frederick Handel's Floridante allows Gay's work to be placed in the context of operatic responses to contemporary society, highlighting usage both of overt portrayal and indirect satire. Gay's approach to political issues is examined alongside that of Dean Swift's Gulliver's Travels enabling an estimation to be made of the effectiveness of these art media as tools of political propaganda. Similarly, responses in the field of painting are discussed in the light of representative works of James Thornhill and William Hogarth's A Harlot's Progress and A Rake's Progress. In considering all these responses it is noted that art can be interpreted at differing levels, from the sophisticated to the naive. All these art media are then placed in the context of artistic philosophy of the period, thus facilitating an objective assessment of the parallels and differences of art's responses to contemporary issues. Taking into account inherent limitations in the media, to conclude our study, Hogarth's The Beggar's Opera Scenes are compared and contrasted with Gay's prototype. The thesis highlights the trend towards realism in the arts during this period. Nevertheless, we are left with the conundrum that art, 'per se', can only 'mirror' life. It does not necessarily solve its problems. Thesis submitted in fulfilment of the requirements for the degree of Master of Arts in Music. University of Durham Department of Music 198
CODEX clusters - Survey, catalog, and cosmology of the X-ray luminosity function
No full textInternational audienceContext. Large area catalogs of galaxy clusters constructed from ROSAT All-Sky Survey provide the basis for our knowledge of the population of clusters thanks to long-term multiwavelength efforts to follow up observations of these clusters.Aims. The advent of large area photometric surveys superseding previous, in-depth all-sky data allows us to revisit the construction of X-ray cluster catalogs, extending the study to lower cluster masses and higher redshifts and providing modeling of the selection function.Methods. We performed a wavelet detection of X-ray sources and made extensive simulations of the detection of clusters in the RASS data. We assigned an optical richness to each of the 24 788 detected X-ray sources in the 10 382 square degrees of the Baryon Oscillation Spectroscopic Survey area using red sequence cluster finder redMaPPer version 5.2 run on Sloan Digital Sky Survey photometry. We named this survey COnstrain Dark Energy with X-ray (CODEX) clusters.Results. We show that there is no obvious separation of sources on galaxy clusters and active galactic nuclei (AGN) based on the distribution of systems on their richness. This is a combination of an increasing number of galaxy groups and their selection via the identification of X-ray sources either by chance or by groups hosting an AGN. To clean the sample, we use a cut on the optical richness at the level corresponding to the 10% completeness of the survey and include it in the modeling of the cluster selection function. We present the X-ray catalog extending to a redshift of 0.6.Conclusions. The CODEX suvey is the first large area X-ray selected catalog of northern clusters reaching fluxes of 10−13 ergs s−1 cm−2. We provide modeling of the sample selection and discuss the redshift evolution of the high end of the X-ray luminosity function (XLF). Our results on z < 0.3 XLF agree with previous studies, while we provide new constraints on the 0.3 < z < 0.6 XLF. We find a lack of strong redshift evolution of the XLF, provide exact modeling of the effect of low number statistics and AGN contamination, and present the resulting constraints on the flat ΛCDM.Key words: surveys / catalogs / large-scale structure of Universe⋆ The catalog of clusters is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/638/A11
Designing organizations in the CCI
No full textDrastic cuts in government budgets will force cultural organizations to reconsider their position by initiating internal discussions on how to avert the risk of these cuts. In order to avoid gradual withering of their proposition, cultural organizations will increasingly search for new organizational constellations with new business models. Converting the cultural organization into a hybrid organization combining cultural as well as business values, is one of the options and a major challenge. There seems to be pressure on preserving the cultural values that belong to the artistic core. This paper investigates the application of the IDER-model, that combines design thinking and design related implementation theories that take the potential conflicting value systems into account as well as a focus on the subsequent realization of associated organizational changes. An additional challenge is to realize the new structure in a way that it stays flexible as were it of a prototypical nature. Based on this theoretical discussion the paper proposes an agenda for future research to generalise our findings. The model explicated in the paper relates to the fundamental choices underlying the adaption to external changes through hybridization.Product Innovation ManagementIndustrial Design Engineerin
Offset between X-ray and optical centers in clusters of galaxies: Connecting eROSITA data with simulations
No full textContext. The characterization of the dynamical state of galaxy clusters is key to studying their evolution, evaluating their selection, and using them as a cosmological probe. In this context, the offsets between different definitions of the center have been used to estimate the cluster disturbance.
Aims. Our goal is to study the distribution of the offset between the X-ray and optical centers in clusters of galaxies. We study the offset for clusters detected by the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spectrum-Roentgen-Gamma (SRG) observatory. We aim to connect observations to predictions by hydrodynamical simulations and N-body models. We assess the astrophysical effects affecting the displacements.
Methods. We measured the offset for clusters observed in the eROSITA Final Equatorial-Depth Survey (eFEDS) and the first eROSITA all-sky survey (eRASS1). We focus on a subsample of 87 massive eFEDS clusters at low redshift, with M500c > 1×1014 M⊙ and 0.15 < z < 0.4. We compared the displacements in such sample to those predicted by the TNG and the Magneticum simulations. We additionally link the observations to the offset parameter Xoff measured for dark matter halos in N-body simulations, using the hydrodynamical simulations as a bridge.
Results. We find that, on average, the eFEDS clusters show a smaller offset compared to eRASS1 because the latter contains a larger fraction of massive and disturbed structures. We measured an average offset of kpc, when focusing on the subsample of 87 eFEDS clusters. This is in agreement with the predictions from TNG and Magneticum, and the distribution of Xoff from dark matter only (DMO) simulations. However, the tails of the distributions are different. Using ΔX − O to classify relaxed and disturbed clusters, we measured a relaxed fraction of 31% in the eFEDS subsample. Finally, we found a correlation between the offset measured on hydrodynamical simulations and Xoff measured on their parent dark-matter-only run and we calibrated the relation between them.
Conclusions. We conclude that there is good agreement between the offsets measured in eROSITA data and the predictions from simulations. Baryonic effects cause a decrement (increment) in the low (high) offset regime compared to the Xoff distribution from dark matter-only simulations. The offset–Xoff relation provides an accurate prediction of the true Xoff distribution in Magneticum and TNG. It allows for the offsets to be introduced in a cosmological context with a new method in order to marginalize over selection effects related to the cluster dynamical state
Comparative analysis of Mycobacterium tuberculosis pe and ppe genes reveals high sequence variation and an apparent absence of selective constraints.
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110619.pdf (Publisher’s version ) (Open Access)Mycobacterium tuberculosis complex (MTBC) genomes contain 2 large gene families termed pe and ppe. The function of pe/ppe proteins remains enigmatic but studies suggest that they are secreted or cell surface associated and are involved in bacterial virulence. Previous studies have also shown that some pe/ppe genes are polymorphic, a finding that suggests involvement in antigenic variation. Using comparative sequence analysis of 18 publicly available MTBC whole genome sequences, we have performed alignments of 33 pe (excluding pe_pgrs) and 66 ppe genes in order to detect the frequency and nature of genetic variation. This work has been supplemented by whole gene sequencing of 14 pe/ppe (including 5 pe_pgrs) genes in a cohort of 40 diverse and well defined clinical isolates covering all the main lineages of the M. tuberculosis phylogenetic tree. We show that nsSNP's in pe (excluding pgrs) and ppe genes are 3.0 and 3.3 times higher than in non-pe/ppe genes respectively and that numerous other mutation types are also present at a high frequency. It has previously been shown that non-pe/ppe M. tuberculosis genes display a remarkably low level of purifying selection. Here, we also show that compared to these genes those of the pe/ppe families show a further reduction of selection pressure that suggests neutral evolution. This is inconsistent with the positive selection pressure of "classical" antigenic variation. Finally, by analyzing such a large number of genes we were able to detect large differences in mutation type and frequency between both individual genes and gene sub-families. The high variation rates and absence of selective constraints provides valuable insights into potential pe/ppe function. Since pe/ppe proteins are highly antigenic and have been studied as potential vaccine components these results should also prove informative for aspects of M. tuberculosis vaccine design
SPIDERS: overview of the X-ray galaxy cluster follow-up and the final spectroscopic data release
No full text19 pages, 21 figures. Accepted for publication in MNRASInternational audienceSPIDERS (The SPectroscopic IDentification of eROSITA Sources) is a large spectroscopic programme for X-ray selected galaxy clusters as part of the Sloan Digital Sky Survey-IV (SDSS-IV). We describe the final dataset in the context of SDSS Data Release 16 (DR16): the survey overall characteristics, final targeting strategies, achieved completeness and spectral quality, with special emphasis on its use as a galaxy cluster sample for cosmology applications. SPIDERS now consists of about 27,000 new optical spectra of galaxies selected within 4,000 photometric red sequences, each associated with an X-ray source. The excellent spectrograph efficiency and a robust analysis pipeline yield a spectroscopic redshift measurement success rate exceeding 98%, with a median velocity accuracy of 20 km s^{-1} (at z=0.2). Using the catalogue of 2,740 X-ray galaxy clusters confirmed with DR16 spectroscopy, we reveal the three-dimensional map of the galaxy cluster distribution in the observable Universe up to z ~ 0.6. We highlight the homogeneity of the member galaxy spectra among distinct regions of the galaxy cluster phase space. Aided by accurate spectroscopic redshifts and by a model of the sample selection effects, we compute the galaxy cluster X-ray luminosity function and we present its lack of evolution up to z=0.6. Finally we discuss the prospects of forthcoming large multiplexed spectroscopic programmes dedicated to follow up the next generation of all-sky X-ray source catalogues
Clustering of CODEX clusters
No full textContext. The clustering of galaxy clusters links the spatial nonuniformity of dark matter halos to the growth of the primordial spectrum of perturbations. The amplitude of the clustering signal is widely used to estimate the halo mass of astrophysical objects. The advent of cluster mass calibrations enables using clustering in cosmological studies.
Aims. We analyze the autocorrelation function of a large contiguous sample of galaxy clusters, the Constrain Dark Energy with X-ray (CODEX) sample, in which we take particular care of cluster definition. These clusters were X-ray selected using the ROentgen SATellite All-Sky Survey and then identified as galaxy clusters using the code redMaPPer run on the photometry of the Sloan Digital Sky Survey. We develop methods for precisely accounting for the sample selection effects on the clustering and demonstrate their robustness using numerical simulations.
Methods. Using the clean CODEX sample, which was obtained by applying a redshift-dependent richness selection, we computed the two-point autocorrelation function of galaxy clusters in the 0.1 < z < 0.3 and 0.3 < z < 0.5 redshift bins. We compared the bias in the measured correlation function with values obtained in numerical simulations using a similar cluster mass range.
Results. By fitting a power law, we measured a correlation length r0 = 18.7 ± 1.1 and slope γ = 1.98 ± 0.14 for the correlation function in the full redshift range. By fixing the other cosmological parameters to their nine-year Wilkinson Microwave Anisotropy Probe values, we reproduced the observed shape of the correlation function under the following cosmological conditions: and with estimated additional systematic errors of σΩm0 = 0.02 and σS8 = 0.20. We illustrate the complementarity of clustering constraints by combining them with CODEX cosmological constraints based on the X-ray luminosity function, deriving Ωm0 = 0.25 ± 0.01 and with an estimated additional systematic error of σΩm0 = 0.07 and σσ8 = 0.04. The mass calibration and statistical quality of the mass tracers are the dominant source of uncertainty
