Santa and the moon

Happy end-of-the-year evening and night events provide good opportunities to explain the phases of the moon. The need for such moon phase education is once again demonstrated, through an investigation of illustrations on Santa Claus and Christmas gift wrap and in children's books, in two countries which have been important in shaping the image of Santa Claus and his predecessor Sinterklaas: The Netherlands and the USA. The moon on Halloween illustrations is also considered. The lack of knowledge concerning the physical origin of the moon phases, or lack of interest in understanding, is found to be widespread in The Netherlands but is also clearly present in the USA, and is quite possibly global. Definitely incomplete, but surely representative lists compiling both scientifically correct and scientifically incorrect gift wrap and children's books are also presented.Comment: Text, plus 4 figures and 4 tables; to appear in vol.12 of the Communicating Astronomy to the Public Journal (December 2011

Herschel and Galaxies/AGN

Herschel will represent a breakthrough in the study of nearby gas-rich and gas-poor galaxies, as it will for the first time permit imaging photometric and spectroscopic observations of their ISM in the FIR-submm wavelength range. The unprecedented sensitivity and angular resolution of Herschel will furthermore yield a breakthrough in our understanding of distant galaxies and AGN, as their gas and dust - both the ISM- and the AGN-related - will for the first time come within reach. Herschel will undoubtedly yield major discoveries concerning the cosmologically evolving gas and dust properties in galaxies, back to very early epochs.Comment: Invited review, at conference "The Dusty and Molecular Universe - A Prelude to HERSCHEL and ALMA", Paris, 27-29 October 200

An AGN Hertzsprung-Russell Diagram

Detailed examination of the balance between star-formation and nuclear activity in AGN and starburst galaxies leads to the composition of an Hertzsprung-Russell diagram in which possible evolutionary tracks can be drawn. It is likely that these tracks also relate to the level of obscuration.Comment: Contribution for Elba Conference "Issues in Unification of AGNs

Radio imaging of core-dominated high redshift quasars

VLA imaging at kiloparsec-scale resolution of sixteen core-dominated radio-loud QSOs is presented. Many objects appear to display variable radio emission and their radio morphologies are significantly smaller than those of steep-spectrum quasars, consistent with these objects being observed at sight lines close to their (relativistic, $\gamma \approx$ 4-7) jet axes. The usefulness of the radio source orientation indicator R_V, being defined as ratio of radio core and rest frame optical V-band luminosity, is confirmed.Comment: 11 pages, 11 postscript figures, uses aa.cls 4.03 for LaTeX2e To appear in Astronomy and Astrophysic

1245+676 - a CSO/GPS source being an extreme case of a double-double structure

AGN with the so-called `double-double' radio structure have been interpreted as restarted AGN where the inner structure is a manifestation of a new phase of activity which happened to begin before the outer radio lobes resulting from the previous one had faded completely. The radio galaxy 1245+676 is an extreme example of such a double-double object - its outer structure, measuring 970 h^{-1} kpc, is five orders of magnitude larger than the 9.6 h^{-1} pc inner one. We present a series of VLBI observations of the core of 1245+676 which appears to be a compact symmetric object (CSO). We have detected the motion of the CSO's lobes, measured its velocity, and inferred the kinematic age of that structure.Comment: A contribution to The Third Workshop on Compact Steep Spectrum and GHz-Peaked Spectrum Radio Sources, Kerastari, Greece May 28-31, 2002. Refereed and accepted by Publications of the Astronomical Society of Australia. 4 pages. Final version copyedited by PASA Edito

Staphylococcus aureus proteins Sbi and Efb recruit human plasmin to degrade complement C3 and C3b

Upon host infection, the human pathogenic microbe Staphylococcus aureus (S. aureus) immediately faces innate immune reactions such as the activated complement system. Here, a novel innate immune evasion strategy of S. aureus is described. The staphylococcal proteins surface immunoglobulin-binding protein (Sbi) and extracellular fibrinogen-binding protein (Efb) bind C3/C3b simultaneously with plasminogen. Bound plasminogen is converted by bacterial activator staphylokinase or by host-specific urokinase-type plasminogen activator to plasmin, which in turn leads to degradation of complement C3 and C3b. Efb and to a lesser extend Sbi enhance plasmin cleavage of C3/C3b, an effect which is explained by a conformational change in C3/C3b induced by Sbi and Efb. Furthermore, bound plasmin also degrades C3a, which exerts anaphylatoxic and antimicrobial activities. Thus, S. aureus Sbi and Efb comprise platforms to recruit plasmin(ogen) together with C3 and its activation product C3b for efficient degradation of these complement components in the local microbial environment and to protect S. aureus from host innate immune reactions

Visualization and Evolution of Software Architectures

Software systems are an integral component of our everyday life as we find them in tools and embedded in equipment all around us. In order to ensure smooth, predictable, and accurate operation of these systems, it is crucial to produce and maintain systems that are highly reliable. A well-designed and well-maintained architecture goes a long way in achieving this goal. However, due to the intangible and often complex nature of software architecture, this task can be quite complicated. The field of software architecture visualization aims to ease this task by providing tools and techniques to examine the hierarchy, relationship, evolution, and quality of architecture components. In this paper, we present a discourse on the state of the art of software architecture visualization techniques. Further, we highlight the importance of developing solutions tailored to meet the needs and requirements of the stakeholders involved in the analysis process

Multi-source self-calibration: Unveiling the microJy population of compact radio sources

Context. Very Long Baseline Interferometry (VLBI) data are extremely sensitive to the phase stability of the VLBI array. This is especially important when we reach {\mu}Jy r.m.s. sensitivities. Calibration using standard phase referencing techniques is often used to improve the phase stability of VLBI data but the results are often not optimal. This is evident in blank fields that do not have in-beam calibrators. Aims. We present a calibration algorithm termed Multi-Source Self-Calibration (MSSC) which can be used after standard phase referencing on wide-field VLBI observations. This is tested on a 1.6 GHz wide-field VLBI data set of the Hubble Deep Field-North and the Hubble Flanking Fields. Methods. MSSC uses multiple target sources detected in the field via standard phase referencing techniques and modifies the visibili- ties so that each data set approximates to a point source. These are combined to increase the signal to noise and permit self-calibration. In principle, this should allow residual phase changes caused by the troposphere and ionosphere to be corrected. By means of faceting, the technique can also be used for direction dependent calibration. Results. Phase corrections, derived using MSSC, were applied to a wide-field VLBI data set of the HDF-N comprising of 699 phase centres. MSSC was found to perform considerably better than standard phase referencing and single source self-calibration. All detected sources exhibited dramatic improvements in dynamic range. Using MSSC, one source reached the detection threshold taking the total detected sources to twenty. 60% of these sources can now be imaged with uniform weighting compared to just 45% with standard phase referencing. The Parseltongue code which implements MSSC has been released and made publicly available to the astronomical community (https://github.com/jradcliffe5/multi_self_cal).Comment: 7 pages, 4 figures, accepted to A&