VLA and ATCA Search for Natal Star Clusters in Nearby Star-Forming Galaxies

In order to investigate the relationship between the local environment and the properties of natal star clusters, we obtained radio observations of 25 star-forming galaxies within 20 Mpc using the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA). Natal star-forming regions can be identified by their characteristic thermal radio emission, which is manifest in their spectral index at centimeter wavelengths. The host galaxies in our sample were selected based upon their likelihood of harboring young star formation. In star-forming regions, the ionizing flux of massive embedded stars powers the dominant thermal free-free emission of those sources, resulting in a spectral index of {\alpha} {\gtrsim} -0.2 (where S{\nu} {\propto} {\nu}{\alpha}), which we compute. With the current sensitivity, we find that of the 25 galaxies in this sample only five have radio sources with spectral indices that are only consistent with a thermal origin; four have radio sources that are only consistent with a non-thermal origin; six have radio sources whose nature is ambiguous due to uncertainties in the spectral index; and sixteen have no detected radio sources. For those sources that appear to be dominated by thermal emission, we infer the ionizing flux of the star clusters and the number of equivalent O7.5 V stars that are required to produce the observed radio flux densities. The most radio-luminous clusters that we detect have an equivalent of ~7x103 O7.5 V stars, and the smallest only have an equivalent of ~102 O7.5 V stars; thus these star-forming regions span the range of large OB-associations to moderate "super star clusters" (SSCs). With the current detection limits, we also place upper limits on the masses of clusters that could have recently formed...Comment: Subject headings: galaxies: star clusters--galaxies: irregular--galaxies: starburst--stars: formation--HII regions 34 pages, 11 figures, accepted for publication in The Astronomical Journal (1 February 2011

Therapeutic advances in the treatment of vasculitis

Considerable therapeutic advances for the treatment of vasculitis of the young have been made in the past 10 years, including the development of outcome measures that facilitate clinical trial design. Notably, these include: a recognition that some patients with Kawasaki Disease require corticosteroids as primary treatment combined with IVIG; implementation of rare disease trial design for polyarteritis nodosa to deliver the first randomised controlled trial for children; first clinical trials involving children for anti-neutrophil cytoplasmic antibody (ANCA) vasculitis; and identification of monogenic forms of vasculitis that provide an understanding of pathogenesis, thus facilitating more targeted treatment. Robust randomised controlled trials for Henoch Schönlein Purpura nephritis and Takayasu arteritis are needed; there is also an over-arching need for trials examining new agents that facilitate corticosteroid sparing, of particular importance in the paediatric population since glucocorticoid toxicity is a major concern

Impaired function of endothelial progenitor cells in children with primary systemic vasculitis

INTRODUCTION: Previously, we demonstrated that children with active systemic vasculitis (SV) have higher circulating CD34 + CD133 + KDR+ endothelial progenitor cells (EPC); the function of these EPCs, and their relationship with disease activity in vasculitis remains largely unexplored. We hypothesized that although EPC numbers are higher, EPC function is impaired in active SV of the young. The aims of this study were therefore to: 1. investigate the relationship between disease activity and EPC function in children with SV; and 2. study the influence of systemic inflammation on EPC function by investigating the effects of hyperthermia and TNF-α on EPC function. METHODS: We performed a cross-sectional study of unselected children with SV with different levels of disease activity attending a single center (Great Ormond Street Hospital, London) between October 2008 and December 2014. EPCs were isolated from peripheral blood of children with SV, and healthy child controls. EPC function was assessed by their potential to form colonies (EPC-CFU), and ability to form clusters and incorporate into human umbilical vein endothelial cell (HUVEC) vascular structures in matrigel. The effects of hyperthermia and TNF-α on EPC function were also studied. RESULTS: Twenty children, median age 12-years (5-16.5; nine males) were studied. EPC-CFU and the number of EPC clusters formed on matrigel were significantly reduced in children with active vasculitis compared with healthy controls (p = 0.02 for EPC-CFU; p = 0.01 for EPC cluster formation). Those with active vasculitis had lower EPC-CFU and EPC cluster formation than those with inactive disease, although non-significantly so. In addition, EPC incorporation into matrigel HUVEC networks was lower in children with SV compared with healthy children, irrespective of disease activity. Ex-vivo pre-treatment of EPC with hyperthermia impaired EPC function; TNF-α down-regulated EPC expression of CD18/CD11b and resulted in decreased incorporation into HUVEC networks. CONCLUSIONS: Whilst our previous work showed that circulating CD34 + EPC numbers are well preserved, this study revealed that EPC function is significantly impaired in children with vasculitis. It is possible that the chronic inflammatory milieu associated with vasculitis may impair EPC function, and thus contribute to an unfavourable balance between endothelial injury and repair. The mechanism of this remains to be established, however

Takayasu arteritis in childhood: retrospective experience from a tertiary referral centre in the United Kingdom.

Takayasu arteritis (TA) is an idiopathic large-vessel vasculitis affecting the aorta and its major branches. Although the disease rarely affects children, it does occur, even in infants. The objective of this study was to evaluate the clinical features, disease activity, treatment and outcome of childhood TA in a tertiary UK centre

Failure Analysis of Discrete Damaged Tailored Extension-Shear-Coupled Stiffened Composite Panels

The results of an analytical and experimental investigation of the failure of composite is tiffener panels with extension-shear coupling are presented. This tailored concept, when used in the cover skins of a tiltrotor aircraft wing has the potential for increasing the aeroelastic stability margins and improving the aircraft productivity. The extension-shear coupling is achieved by using unbalanced 45 plies in the skin. The failure analysis of two tailored panel configurations that have the center stringer and adjacent skin severed is presented. Finite element analysis of the damaged panels was conducted using STAGS (STructural Analysis of General Shells) general purpose finite element program that includes a progressive failure capability for laminated composite structures that is based on point-stress analysis, traditional failure criteria, and ply discounting for material degradation. The progressive failure predicted the path of the failure and maximum load capability. There is less than 12 percent difference between the predicted failure load and experimental failure load. There is a good match of the panel stiffness and strength between the progressive failure analysis and the experimental results. The results indicate that the tailored concept would be feasible to use in the wing skin of a tiltrotor aircraft

Spatial and Temporal Variations in Small-Scale Galactic HI Structure Toward 3C~138

We present three epochs of VLBA observations of Galactic HI absorption toward the quasar 3C~138 with resolutions of 20 mas (~ 10 AU). This analysis includes VLBA data from observations in 1999 and 2002 along with a reexamination of 1995 VLBA data. Improved data reduction and imaging techniques have led to an order of magnitude improvement in sensitivity compared to previous work. With these new data we confirm the previously detected milliarcsecond scale spatial variations in the HI opacity at the level of Delta(tau_{max}) =0.50 \pm 0.05. The typical size scale of the optical depth variations is ~ 50 mas or 25 AU. In addition, for the first time we see clear evidence for temporal variations in the HI opacity over the seven year time span of our three epochs of data. We also attempted to detect the magnetic field strength in the HI gas using the Zeeman effect. From this analysis we have been able to place a 3 sigma upper limit on the magnetic field strength per pixel of ~45 muG. We have also been able to calculate for the first time the plane of sky covering fraction of the small scale HI gas of ~10%. We also find that the line widths of the milliarcsecond sizescale HI features are comparable to those determined from previous single dish measurements toward 3C~138, suggesting that the opacity variations cannot be due to changes in the HI spin temperature. From these results we favor a density enhancement interpretation for the small scale HI structures, although these enhancements appear to be of short duration and are unlikely to be in equilibrium.Comment: 34 pages, 8 figures. Figures 3 & 4 are in color. Accepted to A

Paediatric Behçet's disease: a UK tertiary centre experience

There are currently limited data regarding paediatric Behçet's disease (BD), particularly in the UK. We describe the clinical spectrum, treatment and outcome of BD, and explore the relative sensitivities of the criteria for the diagnosis of BD in a UK paediatric cohort. Single retrospective case note review of children with a clinical diagnosis of BD presenting between 1987 and 2012. Demographics, clinical features, treatment and outcomes were recorded. The sensitivities of the International Study Group (ISG) and International Criteria for BD (ICBD) criteria were explored. BD disease activity was calculated using the Behçet's Disease Activity Index (BDAI). Forty-six patients (22 male) were identified. Median age of onset was 4.87 (0.04-15.71) years; median time to diagnosis was 3.74 (0.25-13.48) years. Clinical features were recurrent oral ulceration (97.8 %), recurrent genital ulceration (73.9 %), gastrointestinal (58.7 %), musculoskeletal (47.83 %), cutaneous (23.9 %) involvement and uveitis (2 %). Recurrent genital ulceration was more common in female patients (P = 0.044). Thirty-seven patients (80.4 %) fulfilled the ICBD criteria; only 12 patients (26.1 %) fulfilled the ISG criteria. BDAI score at diagnosis was 7/20 (0-10/20) and significantly decreased to 5/20 (0-9/20) (P < 0.0001) at latest follow-up. The commonest systemic treatment was colchicine (76.1 %); anti-TNFα treatment was reserved for severe cases (15.5 %). Paediatric BD in the UK may present very early in life, sometimes with a family history, and with a low incidence of ocular involvement. Diagnostic delay is common. The majority of our patients required systemic therapy; anti-TNFα was reserved for severe cases and has largely superseded the use of thalidomide

Discovery of 35 New Supernova Remnants in the Inner Galaxy

We report the discovery of up to 35 new supernova remnants (SNRs) from a 42 arcsec resolution 90cm multi-configuration Very Large Array survey of the Galactic plane covering 4.5 deg< l <22.0 deg and |b| < 1.25 deg. Archival 20cm, 11cm, and 8 micron data have also been used to identify the SNRs and constrain their properties. The 90cm image is sensitive to SNRs with diameters 2.5 arcmin to 50 arcmin and down to a surface brightness limit of about 10^{-21} W m^{-2} Hz^{-1} sr^{-1}. This survey has nearly tripled the number of SNRs known in this part of the Galaxy, and represents an overall 15% increase in the total number of Galactic SNRs. These results suggest that further deep low frequency surveys of the inner Galaxy will solve the discrepancy between the expected number of Galactic SNRs and the significantly smaller number of currently known SNRs.Comment: 5 pages; Accepted to ApJL, high resolution figures available from http://www.ifa.hawaii.edu/~cbrogan/high_res