Strong lensing statistics in large, z~<0.2 surveys: bias in the lens galaxy population

We calculate the expected lensing statistics of the galaxy population in large, low-redshift surveys. Galaxies are modeled using realistic, multiple components: a dark matter halo, a bulge component and disc. We use semi-analytic models of galaxies coupled with dark matter haloes in the Millennium Run to model the lens galaxy population. We predict that a fraction of 1.4+/-0.18*10^-3 of radio sources will be lensed by galaxies within a survey like the 2dF below z<0.2. With a simulated sample of lensed radio sources, the predicted lensing galaxy population consists mainly of ellipticals (~80%) with an average lens velocity dispersion of 164+/-3 km/s, producing typical image separations of ~3 arcsec. The lens galaxy population lies on the fundamental plane but its velocity dispersion distribution is shifted to higher values compared to all early-type galaxies. Taking magnification bias into account, we predict that the ratio of 4:2 image systems is 30+/-5%, consistent with the observed ratio found in the Cosmic Lens All-Sky Survey. We also find that the population of 4-image lens galaxies is distinguishable from the population of lens galaxies in 2-image systems. Our key result is the explicit demonstration that the population of lens galaxies differs markedly from the galaxy population as a whole: lens galaxies have a higher average luminosity and reside in more massive haloes than the overall sample of ellipticals. This bias restricts our ability to infer galaxy evolution parameters from a sample of lensing galaxies. (abridged)Comment: 13 pages, 13 figures, submitted to MNRAS. Removed double figure and added correct figure

Future management needs of a "software-driven" science community

The work of astronomers is getting more complex and advanced as the progress of computer development occurs. With improved computing capabilities and increased data flow, more sophisticated software is required in order to interpret, and fully exploit, astronomic data. However, it is not possible for every astronomer to also be a software specialist. As history has shown, the work of scientists always becomes increasingly specialised, and we here argue in favour of another, at least partial, split between "programmers" and "interpreters". In this presentation we outline our vision for a new approach and symbiosis between software specialists and scientists, and present its advantages along with a simple test case.Comment: 7 pages, 3 figures, as presented at SPIE Astronomical instrumentation 201

The kinematical structure of gravitationally lensed arcs

In this paper the expected properties of the velocity fields of strongly lensed arcs behind galaxy clusters are investigated. The velocity profile along typical lensed arcs is determined by ray tracing light rays from a model source galaxy through parametric cluster toy-models consisting of individual galaxies embedded in a dark cluster halo. We find that strongly lensed arcs of high redshift galaxies show complex velocity structures that are sensitive to the details of the mass distribution within the cluster, in particular at small scales. From fits to the simulated imaging and kinematic data we demonstrate that reconstruction of the source velocity field is in principle feasible: two dimensional kinematic information obtained with Integral Field Units (IFU's) on large ground based telescopes in combination with adaptive optics will allow the reconstruction of rotation curves of lensed high redshift galaxies. This makes it possible to determine the mass-to-light ratios of galaxies at redshifts z>1 out to about 2-3 scale lengths with better than about 20% accuracy. We also discuss the possibilities of using two dimensional kinematic information along the arcs to give additional constraints on the cluster lens mass models.Comment: 15 pages, 12 figures, 2 tables. Accepted for publication in MNRA

Strong gravitational lensing by spiral galaxies

We investigate gravitational lensing by a realistic model of disk galaxies. Most of the mass is contained in a large spherical isothermal dark matter halo, but the potential is modified significantly in the core by a gravitationally-dominant exponential disk. The method used is adapted from a very general multi-lens ray-tracing technique developed by Moeller. We investigate the effects of the disk-to-halo mass ratio, the disk scale length, the disk inclination to the line of sight and the lens redshift on two strong-lensing cross sections: the cross section for multiple imaging, and the cross section for large magnifications, in excess of a factor of 10. We find that the multiple-imaging cross section can be enhanced significantly by an almost edge-on Milky Way disk as compared with a singular isothermal sphere (SIS) in individual cases; however, when averaged over all disk inclinations, the cross section is only increased by about fifty per cent. These results are consistent with other recent work. The presence of a disk, however, increases the inclination-averaged high-magnification cross section by an order of magnitude as compared with a SIS. This result has important implications for magnification bias in future lens surveys, particularly those in the submillimetre waveband, where dust extinction in the lensing galaxy has no effect on the brightness of the images.Comment: 6 pages, 2 single-panel figures, 2 double-panel figures, one six-panel figure. To appear in MNRA

FIBCD1 Binds Aspergillus fumigatus and Regulates Lung Epithelial Response to Cell Wall Components

Aspergillus fumigatus (A. fumigatus) is a ubiquitous fungus of clinical importance associated with development of various pulmonary diseases and allergic hypersensitivity reactions. It is protected against environmental stress by a cell wall that contains polysaccharides such as chitin. We previously demonstrated that fibrinogen C domain-containing protein 1 (FIBCD1) is a membrane-bound protein that binds chitin through a conserved S1 binding site and is expressed in intestinal epithelium and salivary glands. Here, we further localized FIBCD1 protein expression at the surface of bronchial and alveolar human lung epithelium, observed recognition of A. fumigatus cell wall with S1 site-independent recognition. We observed FIBCD1-mediated suppression of IL-8 secretion, mucin production, and transcription of genes associated with airway inflammation and homeostasis in FIBCD1-transfected lung epithelial cells. These modulations were generally enforced by stimulation with A. fumigatus cell wall polysaccharides. In parallel, we demonstrated a FIBCD1-mediated modulation of IL-8 secretion induced by TLR2,−4, and −5. Collectively, our findings support FIBCD1 as a human lung epithelial pattern recognition receptor that recognizes the complex A. fumigatus cell wall polysaccharides and modulates the lung epithelial inflammatory response by suppressing inflammatory mediators and mucins

MWCNTs of different physicochemical properties cause similar inflammatory responses, but differences in transcriptional and histological markers of fibrosis in mouse lungs

Multi-walled carbon nanotubes (MWCNTs) are extensively produced and used in composite materials and electronic applications, thus increasing risk of worker and consumer exposure. MWCNTs are an inhomogeneous group of nanomaterials that come in various lengths, shapes and with different metal contaminations, which makes hazard evaluation difficult. However, several studies suggest that length plays an important role in the toxicity induced by MWCNTs. How the length influences toxicity at the molecular level is yet to be characterized. Female C57BL/6 mice were exposed by single intratracheal instillation to 18, 54 or 162 µg/mouse of a short MWCNT (NRCWE-026, 847±102 nm in length) or long MWCNT (NM-401, 4048±366 nm in length). The two MWCNTs were extensively characterized. Lung tissues were harvested 24 h, 3 d and 28 d after exposure. We employed DNA microarrays, bronchoalveolar lavage fluid analysis, comet assay and dichlorodihydrofluorescein assay in order to profile the pulmonary responses. Bioinformatics tools were then applied to compare and contrast the expression profiles and to build a length dependent property-response matrix for gene-by-gene comparison. The toxicogenomic analysis of the global mRNA changes after exposure to the short, entangled NRCWE-026 or the longer, stiffer NM-401 showed high degree of similarities. The toxicity of both MWCNTs was driven by strong inflammatory and acute phase responses, which peaked at day 3 and was observed both in bronchoalveolar lavage cell influx and in gene expression profiles. The inflammatory response was sustained at post-exposure day 28. Also, at the sub-chronic level, we identified a sub-set of 14 fibrosis related genes that were uniquely differentially regulated after exposure to NM-401. Acellular ROS production occurred almost exclusively with NRCWE-026, however the longer NM-401 induced in vivo DNA strand breaks and differential regulation of genes involved in free radical scavenging more readily than NRCWE-026. Our results indicate that the global mRNA response after exposure to MWCNTs is length independent at the acute time points, but that fibrosis may be length dependent sub-chronic end point.JRC.H.6-Digital Earth and Reference Dat