75 research outputs found
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
Flame retardants, surfactants and organotins in sediment and mysid shrimp of the Scheldt estuary (The Netherlands)
Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Environmental Pollution 136 (2005): 19-31, doi:10.1016/j.envpol.2004.12.008.Sediment and mysids from the Scheldt estuary, one of the largest and most polluted estuaries in Western Europe, were analyzed for a number of contaminants that have shown to possess endocrine-disrupting activity, i.e. organotins, polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), nonylphenol ethoxylates (NPE) and transformation products nonylphenol (NP) and nonylphenol ether carboxylates (NPEC). In addition, in vitro estrogenic and androgenic potencies of water and sediment extracts were determined. Total organotin concentrations ranged from 84 to 348 ng/g dw in sediment and 1110 to 1370 ng/g dw in mysid. Total PBDE (excluding BDE-209) concentrations ranged from 14 to 22 ng/g dw in sediment and from 1765 to 2962 ng/g lipid in mysid. High concentrations of BDE-209 (240-1650 ng/g dw) were detected in sediment and mysid (269-600 ng/g lipid). Total HBCD concentrations in sediment and mysid were 14-71 ng/g dw and 562-727 ng/g lipid, respectively. Total NPE concentrations in sediment were 1422 ng/g dw, 1222 ng/g dw for NP and 80 ng/g dw for NPEC and ranged from 430 to 1119 ng/g dw for total NPE and from 206 to 435 ng/g dw for NP in mysid. Significant estrogenic potency, as analyzed using the yeast estrogen assay, was detected in sediment and water samples from the Scheldt estuary, but no androgenic activity was found. This study is the first to report high levels of endocrine disruptors in estuarine mysids.Funding to Tim Verslycke was provided by a research grant of the Flemish Institute for the Promotion of Scientific and Technological Research in Industry (IWT-V, Belgium) and a postdoctoral award by the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the Ocean Life Institute. The chemical analysis was financially supported by the National Institute for Coastal and Marine Management (RIKZ, The Netherlands)
Kustlijnen voor Dijkringen: Over de relatie tussen kustlijnzorg en de sterkte van Nederlandse duinwaterkeringen
Voorliggend rapport doet verslag van een studie die Deltares, op verzoek van het Ministerie I&M en het Deltaprogramma Kust, heeft uitgevoerd naar de bijdrage van het programma Kustlijnzorg aan het duurzaam handhaven (of vergroten) van de sterkte van duinwaterkeringen op de middellange en lange termijn. Hiertoe wordt een antwoord gezocht op de volgende deelvragen: 1 Waar bevinden zich de relatief kwetsbare delen van de Nederlandse zeeweringen die gebaat zijn bij reguliere zandsuppleties? 2 Wat is de relatie tussen het aanwezige zandvolume en de sterkte van de duinwaterkering? 3 Wat is de bijdrage van zandsuppleties aan het zandvolume in de kustzone en de sterkte van de duinwaterkering? Wat is daarbij de invloed van de gekozen uitvoeringswijze van suppleren (duin-, strand-, vooroever- of geulwandsuppleties)? 4 Hoe kunnen de bevindingen worden doorvertaald naar de uitvoering, beleidsvoorbereiding en aanbevelingen voor nader onderzoek? Om deze vragen te beantwoorden zijn indicatoren benoemd, waarmee de relatie tussen zandsuppleties en de sterkte van duinwaterkeringen in beeld zijn gebracht. Hiertoe zijn berekeningen en analyses uitgevoerd met JARKUS metingen: metingen van kustprofielen van de Nederlandse kust die sinds 1965 op systematische wijze plaats vinden.Deltaprogramm
Mediators of mucosal inflammation: Implications for therapy
Treatment of inflammatory bowel disease remains a challenge. The major shortcoming in the development of new therapeutic approaches is the fact that the cause of inflammatory bowel disease is still unknown. Recognition of the importance of the arachidonic acid cascade of inflammatory mediators presents the opportunity to specifically inhibit or antagonize leukotriene B4, thromboxane, platelet activating factor, or phospholipase. Interleukins and cytokines have more recently been defined as targets for specific therapy. The results of these specific immune modulating studies are not only important from a therapeutic point of view, but substantially contribute to our understanding of the pathogenic cascades in IBD. In this review, several targets for novel therapeutic intervention are discussed
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
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