HIRAX:A Probe of Dark Energy and Radio Transients

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a new 400-800MHz radio interferometer under development for deployment in South Africa. HIRAX will comprise 1024 six meter parabolic dishes on a compact grid and will map most of the southern sky over the course of four years. HIRAX has two primary science goals: to constrain Dark Energy and measure structure at high redshift, and to study radio transients and pulsars. HIRAX will observe unresolved sources of neutral hydrogen via their redshifted 21-cm emission line (`hydrogen intensity mapping'). The resulting maps of large-scale structure at redshifts 0.8-2.5 will be used to measure Baryon Acoustic Oscillations (BAO). HIRAX will improve upon current BAO measurements from galaxy surveys by observing a larger cosmological volume (larger in both survey area and redshift range) and by measuring BAO at higher redshift when the expansion of the universe transitioned to Dark Energy domination. HIRAX will complement CHIME, a hydrogen intensity mapping experiment in the Northern Hemisphere, by completing the sky coverage in the same redshift range. HIRAX's location in the Southern Hemisphere also allows a variety of cross-correlation measurements with large-scale structure surveys at many wavelengths. Daily maps of a few thousand square degrees of the Southern Hemisphere, encompassing much of the Milky Way galaxy, will also open new opportunities for discovering and monitoring radio transients. The HIRAX correlator will have the ability to rapidly and eXperimentciently detect transient events. This new data will shed light on the poorly understood nature of fast radio bursts (FRBs), enable pulsar monitoring to enhance long-wavelength gravitational wave searches, and provide a rich data set for new radio transient phenomena searches. This paper discusses the HIRAX instrument, science goals, and current status.Comment: 11 pages, 5 figure

Toxicity of harbour canal sediments before dredging and after off shore disposal

Dredge material from an entrance waterway to the port of Rotterdam and sediments from the North Sea off-shore disposal site were tested for toxicity using three different sediment bioassays, The goals of the study were to evaluate if bioassays generate useful additional information to chemical based sediment quality criteria, and to investigate potential changes in toxicity of dredge material after off-shore disposal, Sediment elutriates were tested with larvae of the oyster Crassostrea gigas, whole sediments with the infaunal amphipod Bathyporeia sarsi, and sediment suspensions with the blue mussel Mytilus edulis. The contamination of the investigated dredge material was low according to the limited set of chemical parameters that was analysed, Nevertheless the three bioassays showed that some of the dredge material samples significantly affected the survival of oyster larvae and the amphipod B. sarsi, as well as the aerial survival time of mussels, Toxicity was reduced at the off-shore disposal site, probably due to the dispersal of the most polluted finer sediment fractions by strong residual currents, It is concluded that the sediment bioassays used for this study are a meaningful tool that should be incorparated in decision making frameworks for the management of dredge material. [KEYWORDS: dredge material; off-shore disposal; sediment bioassay; EIA; sediment quality criteria; sediment toxicity North-sea sediments; mytilus-edulis-l; contaminated sediment; bioassays; american; survival; amphipod; tests]

Effect of intestinal resection on serum antibodies to the mycobacterial 45/48 kilodalton doublet antigen in Crohn's disease.

Interest in the role of mycobacterial infection in Crohn's disease has been revived by the cultural detection of Mycobacterium paratuberculosis in patients with Crohn's disease. This hypothesis was examined serologically using assays with high specificity for Crohn's disease. The effect of intestinal resection on serum antibodies specific for Crohn's disease was investigated with an immunoblot assay and an enzyme linked immunosorbent assay using the 45/48 kilodalton doublet antigen of Mycobacterium tuberculosis. Antibodies were detected in 64.7% of patients with Crohn's disease (n = 17), 10% of patients with ulcerative colitis (n = 10), 5% of patients with carcinoma of the colon (n = 20), and none of 10 healthy subjects with the immunoblot assay. Statistical comparison of the Crohn's disease patients with each control group resulted in p = 0.0000236. Immunoglobulin G was essentially unchanged 75 days (mean) after surgery. After more than 180 days, however, the antibody response was reduced in all of five patients studied, and was no longer demonstrable in two of them (40%). Simultaneously, the Crohn's disease activity index (CDAI) decreased. Both the high specificity of this assay for Crohn's disease and the diminished antibody response after intestinal resection in parallel with decreased CDAI support a mycobacterial aetiology of Crohn's disease

The prevalence of nodular regenerative hyperplasia of the liver in long-term thiopurine-treated inflammatory bowel disease patients

INTRODUCTION: Nodular regenerative hyperplasia (NRH) has been associated with thiopurine therapy in patients with inflammatory bowel disease (IBD), but prevalence and prognosis of NRH remain unclear. This study is a cross-sectional search for NRH in IBD patients with long-term azathioprine or 6-mercaptopurine treatment. MATERIAL AND METHODS: Thirty-three IBD patients with continuous azathioprine/6-mercaptopurine treatment for at least 5 years were included. Laboratory tests, thiopurine metabolite levels, liver histology, MRI were examined for NRH and signs of portal hypertension. RESULTS: NRH was not observed in this cohort of 33 patients. Nevertheless, some possibly related signs of vascular changes were found by MRI in three patients. Also, splenomegaly, which may be associated with portal hypertension, was found in one patient. No high thiopurine dose neither high metabolite levels were found in these patients. CONCLUSION: No NRH was found in this group of IBD patients with long-term azathioprine/6-mercaptopurine treatment. Larger multicenter studies are needed to determine the prevalence of NRH in thiopurine-treated IBD patients