We introduce a new effective strategy to assign group and cluster membership probabilities Pmem to galaxies using photometric redshift information. Large dynamical ranges both in halo mass and cosmic ...time are considered. The method takes into account the magnitude distribution of both cluster and field galaxies as well as the radial distribution of galaxies in clusters using a non-parametric formalism, and relies on Bayesian inference to take photometric redshift uncertainties into account. We successfully test the method against 1208 galaxy clusters within redshifts z = 0.05−2.58 and masses 1013.29−14.80M⊙ drawn from wide field simulated galaxy mock catalogs mainly developed for the forthcoming Euclid mission. Median purity and completeness values of (55+17-15)% and (95+5-10)% are reached for galaxies brighter than 0.25 L∗ within r200 of each simulated halo and for a statistical photometric redshift accuracy σ((zs−zp)/(1 + zs)) = 0.03. The mean values p̅=56% and c̅=93% are consistent with the median and have negligible sub-percent uncertainties. Accurate photometric redshifts (σ((zs−zp)/(1 + zs)) ≲ 0.05) and robust estimates for the cluster redshift and cluster center coordinates are required. The dependence of the assignments on photometric redshift accuracy, galaxy magnitude and distance from the halo center, and halo properties such as mass, richness, and redshift are investigated. Variations in the mean values of both purity and completeness are globally limited to a few percent. The largest departures from the mean values are found for galaxies associated with distant z ≳ 1.5 halos, faint (~0.25 L∗) galaxies, and those at the outskirts of the halo (at cluster-centric projected distances ~r200) for which the purity is decreased, Δp ≃ 20% at most, with respect to the mean value. The proposed method is applied to derive accurate richness estimates. A statistical comparison between the true (Ntrue) vs. estimated richness (λ = ∑ Pmem) yields on average to unbiased results, Log(λ/Ntrue) = −0.0051 ± 0.15. The scatter around the mean of the logarithmic difference between λ and the halo mass is 0.10 dex for massive halos ≳1014.5M⊙. Our estimates could therefore be useful to constrain the cluster mass function and to calibrate independent cluster mass estimates such as those obtained from weak lensing, Sunyaev-Zel’dovich, and X-ray studies. Our method can be applied to any list of galaxy clusters or groups in both present and forthcoming surveys such as SDSS, CFHTLS, Pan-STARRS, DES, LSST, and Euclid.
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Context. Low luminosity radio galaxies (LLRGs) typically reside in dense megaparsec-scale environments and are often associated with brightest cluster galaxies (BCGs). They are an excellent tool to ...study the evolution of molecular gas reservoirs in giant ellipticals, even close to the active galactic nucleus. Aims. We investigate the role of dense megaparsec-scale environment in processing molecular gas in LLRGs in the cores of galaxy (proto-)clusters. To this aim we selected within the COSMOS and DES surveys a sample of five LLRGs at z = 0.4−2.6 that show evidence of ongoing star formation on the basis of their far-infrared (FIR) emission. Methods. We assembled and modeled the FIR-to-UV spectral energy distributions (SEDs) of the five radio sources to characterize their host galaxies in terms of stellar mass and star formation rate. We observed the LLRGs with the IRAM-30 m telescope to search for CO emission. We then searched for dense megaparsec-scale overdensities associated with the LLRGs using photometric redshifts of galaxies and the Poisson Probability Method, which we have upgraded using an approach based on the wavelet-transform (wPPM), to ultimately characterize the overdensity in the projected space and estimate the radio galaxy miscentering. Color-color and color-magnitude plots were then derived for the fiducial cluster members, selected using photometric redshifts. Results. Our IRAM-30 m observations yielded upper limits to the CO emission of the LLRGs, at z = 0.39, 0.61, 0.91, 0.97, and 2.6. For the most distant radio source, COSMOS-FRI 70 at z = 2.6, a hint of CO(7→6) emission is found at 2.2σ. The upper limits found for the molecular gas content M(H2)/M⋆ < 0.11, 0.09, 1.8, 1.5, and 0.29, respectively, and depletion time τdep ≲ (0.2−7) Gyr of the five LLRGs are overall consistent with the corresponding values of main sequence field galaxies. Our SED modeling implies large stellar-mass estimates in the range log(M⋆/M⊙) = 10.9−11.5, typical for giant ellipticals. Both our wPPM analysis and the cross-matching of the LLRGs with existing cluster/group catalogs suggest that the megaparsec-scale overdensities around our LLRGs are rich (≲1014 M⊙) groups and show a complex morphology. The color-color and color-magnitude plots suggest that the LLRGs are consistent with being star forming and on the high-luminosity tail of the red sequence. The present study thus increases the still limited statistics of distant cluster core galaxies with CO observations. Conclusions. The radio galaxies of this work are excellent targets for ALMA as well as next-generation telescopes such as the James Webb Space Telescope.
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Mast cells in autoimmune disease Benoist, Christophe; Mathis, Diane
Nature (London),
26/2002 Dec 19, Volume:
420, Issue:
6917
Journal Article
Peer reviewed
Mast cells are known to be the primary responders in allergic reactions, orchestrating strong responses to minute amounts of allergens. Several recent observations indicate that they may also have a ...key role in coordinating the early phases of autoimmune diseases, particularly those involving auto-antibodies.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Autoimmune diseases remain one of the mysteries that perplex immunologists. What makes the immune system, which has evolved to protect an organism from foreign invaders, turn on the organism itself? ...A popular answer to this question involves the lymphoid network's primordial function: autoimmunity is a by-product of the immune response to microbial infection. For decades there have been tantalizing associations between infectious agents and autoimmunity: beta-hemolytic streptococci and rheumatic fever; B3 Coxsackieviruses and myocarditis; Trypanosoma cruzi and Chagas' disease; diverse viruses and multiple sclerosis; Borrelia burgdorfii and Lyme arthritis; and B4 Coxsackievirus, cytomegalovirus or rubella and type 1 diabetes, to name the most frequently cited examples. In addition, animal models have provided direct evidence that infection with a particular microbe can incite a particular autoimmune disease. Nonetheless, many of the associations appear less than convincing and, even for those that seem to be on solid footing, there is no real understanding of the underlying mechanism(s).
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This paper presents 52 X-ray bright galaxy clusters selected within the 11 deg2
XMM-LSS survey. 51 of them have spectroscopic redshifts (0.05 < z < 1.06), one is identified at z
phot = 1.9, and all ...together make the high-purity ‘Class 1’ (C1) cluster sample of the XMM-LSS, the highest density sample of X-ray-selected clusters with a monitored selection function. Their X-ray fluxes, averaged gas temperatures (median T
X = 2 keV), luminosities (median L
X, 500 = 5 × 1043 erg s−1) and total mass estimates (median 5 × 1013 h
−1 M⊙) are measured, adapting to the specific signal-to-noise regime of XMM-LSS observations. Particular care is taken in deriving the sample selection function by means of realistic simulations reproducing the main characteristics of XMM observations. The redshift distribution of clusters shows a deficit of sources when compared to the cosmological expectations, regardless of whether Wilkinson Microwave Anisotropy Probe-9 or Planck-2013 cosmic microwave background parameters are assumed. This lack of sources is particularly noticeable at 0.4 ≲ z ≲ 0.9. However, after quantifying uncertainties due to small number statistics and sample variance, we are not able to put firm (i.e. >3σ) constraints on the presence of a large void in the cluster distribution. We work out alternative hypotheses and demonstrate that a negative redshift evolution in the normalization of the L
X-T
X relation (with respect to a self-similar evolution) is a plausible explanation for the observed deficit. We confirm this evolutionary trend by directly studying how C1 clusters populate the L
X-T
X-z space, properly accounting for selection biases. We also point out that a systematically evolving, unresolved, central component in clusters and groups (AGN contamination or cool core) can impact the classification as extended sources and be partly responsible for the observed redshift distribution. We provide in a table the catalogue of 52 clusters together with their measured properties.
•The gaseous emissions produced by various composting process conditions were characterized and quantified.•Nine compounds were potentially odorous: TMA, NH3, 2-pentanone, 1-propanol-2-methyl, ...acetophenone and sulphur forms.•The tested composting process conditions reduced odour emissions by a factor of 5–10.•A reduction of 105 to 106 is required to reach an odour threshold limit at peak event emissions.•Both aeration rate and bulking agent had the most impact on reducing odour emissions.
Compost sustainability requires a better control of its gaseous emissions responsible for several impacts including odours. Indeed, composting odours have stopped the operation of many platforms and prevented the installation of others. Accordingly, present technologies collecting and treating gases emitted from composting are not satisfactory and alternative solutions must be found. Thus, the aim of this paper was to study the influence of composting process conditions on gaseous emissions. Pig slaughterhouse sludge mixed with wood chips was composted under forcedaerationin 300L laboratory reactors. The process conditions studied were: aeration rate of 1.68, 4.03, 6.22, 9.80 and 13.44L/h/kg of wet sludge; incorporation ratio of 0.55, 0.83 and 1.1 (kg of wet wood chips/kg of wet sludge), and; bulking agent particles size of <10, 10<20 and 20<30mm. Out-going gases were sampled every 2days and their composition was analysed using gas chromatography coupled with mass spectrometry (GC–MS). Fifty-nine compounds were identified and quantified. Dividing the cumulated mass production over 30days of composting, by odour threshold, 9 compounds were identified as main potential odour contributors: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone, 1-propanol-2-methyl, dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide and acetophenone. Five gaseous compounds were correlated with both aeration rate and bulking agent to waste ratio: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone and 1-propanol-2-methyl. However, dropping the aeration rate and increasing the bulking agent to waste ratio reduced gaseous odour emissions by a factor of 5–10, when the required threshold dilution factor ranged from 105 to 106, to avoid nuisance at peak emission rates. Process influence on emissions of dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide were poorly correlated with both aeration rate and bulking agent to waste ratio as a reaction with hydrogen sulphide was suspected. Acetophenone emissions originated from the wood chips. Olfactory measurements need to be correlated to gaseous emissions for a more accurate odour emission evaluation.
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The paper focused on the modelling of the heat transfers during composting in a pilot-scale reactor under forced aeration. The model took into account the heat production and the transfers by ...evaporation, convection between material and gas crossing the material, conduction and surface convection between gas and material in bottom and upper parts of the reactor. The model was adjusted thanks to the measurements practised during fifteen composting experiments in which five organic wastes were, each, composted under three constant aeration rates. Heat production was considered proportional to oxygen consumption rate and the enthalpy per mole oxygen consumed was assumed constant. The convective heat transfer coefficients were determined on basis of the continuous measurements of the temperatures of both the lid and the bottom part of the reactor. The model allowed a satisfying prediction of the temperature of the composting material. In most cases, the mean absolute discard between the experimental and the simulated temperatures was inferior to 2.5°C and the peaks of temperature occurred with less than 8h delay. For the half of the experiments the temperature discard between the simulated peak and the experimental one was inferior to 5°C. On basis of the calculation of a stoichiometric production of water through oxidation of the biodegradable organic matter, the simulation of water going out from material as vapour also allowed a rather satisfying prediction of the mass of water in final mixture. The influence of the aeration rate on every type of heat loss was characterized. Finally, the model was used to evaluate the impacts on material temperature caused by the change of the insulation thickness, the ambient temperature, take the lid away, the increase or the decrease of the mass of waste to compost.
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9.
The XXL Survey Pompei, E; Adami, C; Eckert, D ...
Astronomy and astrophysics (Berlin),
08/2016, Volume:
592
Journal Article
Peer reviewed
Context. The XXL Survey is the largest homogeneous and contiguous survey carried out with XMM-Newton. Covering an area of 50 deg super(2) distributed over two fields, it primarily investigates the ...large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. Aims. Given its depth and sky coverage, XXL is particularly suited to systematically unveiling the clustering of X-ray clusters and to identifying superstructures in a homogeneous X-ray sample down to the typical mass scale of a local massive cluster. Methods. A friends-of-friends algorithm in three-dimensional physical space was run to identify large-scale structures. In this paper we report the discovery of the highest redshift supercluster of galaxies found in the XXL Survey. We describe the X-ray properties of the clusters members of the structure and the optical follow-up. Results. The newly discovered supercluster is composed of six clusters of galaxies at a median redshift z~ 0.43 and distributed across ~30x 15 (10 x 5 Mpc) on the sky. This structure is very compact with all the clusters residing in one XMM pointing; for this reason this is the first supercluster discovered with the XXL Survey. Photometric redshifts from the CFHTLS (Canada-France-Hawaii Telescope Legacy Survey) data release T0007 placed the supercluster at an approximate redshift of z sub(phot)~ 0.45; subsequent spectroscopic follow-up with WHT (William Herschel Telescope) and NTT (New Technology Telescope) confirmed a median redshift of z~ 0.43. An estimate of the X-ray mass and luminosity of this supercluster returns values of 1.7 x 10 super(15)M sub(?) and of 1.68 x 10 super(44) ergs super(-1), respectively, and a total gas mass of M sub(gas)= 9.3 x 10 super(13)M sub(?). These values put XLSSC-e at the average mass range of superclusters; its appearance, with two members of equal size, is quite unusual with respect to other superclusters and provides a unique view of the formation process of a massive structure.
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The XXL Survey Ricci, M.; Benoist, C.; Maurogordato, S. ...
Astronomy and astrophysics (Berlin),
12/2018, Volume:
620
Journal Article
Peer reviewed
Open access
Context. The luminosity function (LF) is a powerful statistical tool used to describe galaxies and learn about their evolution. In particular, the LFs of galaxies inside clusters allow us to better ...understand how galaxies evolve in these dense environments. Knowledge of the LFs of galaxies in clusters is also crucial for clusters studies in the optical and near-infrared (NIR) as they encode, along with their density profiles, most of their observational properties. However, no consensus has been reached yet about the evolution of the cluster galaxy LF with halo mass and redshift. Aims. The main goal of this study is to investigate the LF of a sample of 142 X-ray selected clusters, with spectroscopic redshift confirmation and a well defined selection function, spanning a wide redshift and mass range, and to test the LF dependence on cluster global properties, in a homogeneous and unbiased way. Methods. Our study is based on the Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) photometric galaxy catalogue, associated with photometric redshifts. We constructed LFs inside a scaled radius using a selection in photometric redshift around the cluster spectroscopic redshift in order to reduce projection effects. The width of the photometric redshift selection was carefully determined to avoid biasing the LF and depended on both the cluster redshift and the galaxy magnitudes. The purity was then enhanced by applying a precise background subtraction. We constructed composite luminosity functions (CLFs) by stacking the individual LFs and studied their evolution with redshift and richness, analysing separately the brightest cluster galaxy (BCG) and non-BCG members. We fitted the dependences of the CLFs and BCG distributions parameters with redshift and richness conjointly in order to distinguish between these two effects. Results. We find that the usual photometric redshift selection methods can bias the LF estimate if the redshift and magnitude dependence of the photometric redshift quality is not taken into account. Our main findings concerning the evolution of the galaxy luminosity distribution with redshift and richness are that, in the inner region of clusters and in the redshift-mass range we probe (about 0 < z < 1 and 1013 M⊙ < M500 < 5 × 1014 M⊙), the bright part of the LF (BCG excluded) does not depend much on mass or redshift except for its amplitude, whereas the BCG luminosity increases both with redshift and richness.
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