225 research outputs found
HerMES: A Statistical Measurement of the Redshift Distribution of Herschel-SPIRE Sources Using the Cross-correlation Technique
The wide-area imaging surveys with the Herschel Space Observatory at submillimeter (sub-mm) wavelengths have now resulted in catalogs of the order of one-hundred-thousand dusty, starburst galaxies. These galaxies capture an important phase of galaxy formation and evolution, but, unfortunately, the redshift distribution of these galaxies, N(z), is still mostly uncertain due to limitations associated with counterpart identification at optical wavelengths and spectroscopic follow-up. We make a statistical estimate of N(z) using a clustering analysis of sub-mm galaxies detected at each of 250, 350 and 500 ÎŒm from the Herschel Multi-tiered Extragalactic Survey centered on the Boötes field. We cross-correlate Herschel galaxies against galaxy samples at optical and near-IR wavelengths from the Sloan Digital Sky Survey, the NOAO Deep Wide Field Survey, and the Spitzer Deep Wide Field Survey. We create optical and near-IR galaxy samples based on their photometric or spectroscopic redshift distributions and test the accuracy of those redshift distributions with similar galaxy samples defined with catalogs from the Cosmological Evolution Survey (COSMOS), which has superior spectroscopic coverage. We model the clustering auto- and cross-correlations of Herschel and optical/IR galaxy samples to estimate N(z) and clustering bias factors. The S_(350) > 20 mJy galaxies have a bias factor varying with redshift as b(z) = 1.0^(+1.0)_(â0.5)(1 + z)^1.2^(+0.3)_(â0.7). This bias and the redshift dependence is broadly in agreement with galaxies that occupy dark matter halos of mass in the range of 1012 to 10^(13) M_â. We find that galaxy selections in all three Spectral and Photometric Imaging Receiver (SPIRE) bands share a similar average redshift, with = 1.8 ± 0.2 for 250 ÎŒm selected samples, and = 1.9 ± 0.2 for both 350 and 500 ÎŒm samples, while their distributions behave differently. For 250 ÎŒm selected galaxies we find the a larger number of sources with z †1 when compared with the subsequent two SPIRE bands, with 350 and 500 ÎŒm selected SPIRE samples having peaks in N(z) at progressively higher redshifts. We compare our clustering-based N(z) results to sub-mm galaxy model predictions in the literature, and with an estimate of N(z) using a stacking analysis of COSMOS 24 ÎŒm detections
Roadwork:Expertise at work building roads in the Maldives
This article engages critically with concepts of âskillâ, âexpertiseâ, and âcapacityâ as they operate as markers of distinction and domination and shape migratory labour relations among road construction workers from across South Asia in the Maldives archipelago. The article examines roadwork at three levels: the professional biographies leading to âflexible specializationâ rather than technical expertise amongst Maldivian managers; the technical expertise and social incorporation of âskilledâ Sri Lankan supervisors; and the key material expertise of ânon-skilledâ Bangladeshi labourers in precarious employment. Whilst discussions of South Asian labour migration have been dominated by caste and class, this article argues that it is important to consider how the cultural production and understanding of concepts such as âexpertiseâ, âcapacityâ, and âexposureâ at worksites can (also) become distinguishing factors in (hierarchical) migratory labour relations
Comparing nuclear power trajectories in Germany and the UK: from âregimes' to âdemocraciesâ in sociotechnical transitions and Discontinuities
This paper focuses on arguably the single most striking contrast in contemporary major energy politics in Europe (and even the developed world as a whole): the starkly differing civil nuclear policies of Germany and the UK. Germany is seeking entirely to phase out nuclear power by 2022. Yet the UK advocates a ânuclear renaissanceâ, promoting the most ambitious new nuclear construction programme in Western Europe.Here,this paper poses a simple yet quite fundamental question: what are the particular divergent conditions most strongly implicated in the contrasting developments in these two countries. With nuclear playing such an iconic role in historical discussions over technological continuity and transformation, answering this may assist in wider understandings of sociotechnical incumbency and discontinuity in the burgeoning field ofâsustainability transitionsâ. To this end, an âabductiveâ approach is taken: deploying nine potentially relevant criteria for understanding the different directions pursued in Germany and the UK. Together constituted by 30 parameters spanning literatures related to socio-technical regimes in general as well as nuclear technology in particular, the criteria are divided into those that are âinternalâ and âexternalâ to the âfocal regime configurationâ of nuclear power and associated âchallenger technologiesâ like renewables.
It is âinternalâ criteria that are emphasised in conventional sociotechnical regime theory, with âexternalâ criteria relatively less well explored. Asking under each criterion whether attempted discontinuation of nuclear power would be more likely in Germany or the UK, a clear picture emerges. âInternalâ criteria suggest attempted nuclear discontinuation should be more likely in the UK than in Germanyâ the reverse of what is occurring.
âExternalâ criteria are more aligned with observed dynamics âespecially those relating to military nuclear commitments and broader âqualities of democracyâ. Despite many differences of framing concerning exactly what constitutes âdemocracyâ, a rich political science literature on this point is unanimous in characterising Germany more positively than the UK. Although based only on a single case,a potentially important question is nonetheless raised as to whether sociotechnical regime theory might usefully give greater attention to the general importance of various aspects of democracy in constituting conditions for significant technological discontinuities and transformations. If so, the policy implications are significant. A number of important areas are identified for future research, including the roles of diverse understandings and specific aspects of democracy and the particular relevance of military nuclear commitmentsâ whose under-discussion in civil nuclear policy literatures raises its own questions of democratic accountability
Length of carotid stenosis predicts peri-procedural stroke or death and restenosis in patients randomized to endovascular treatment or endarterectomy.
BACKGROUND: The anatomy of carotid stenosis may influence the outcome of endovascular treatment or carotid endarterectomy. Whether anatomy favors one treatment over the other in terms of safety or efficacy has not been investigated in randomized trials.
METHODS: In 414 patients with mostly symptomatic carotid stenosis randomized to endovascular treatment (angioplasty or stenting; nâ=â213) or carotid endarterectomy (nâ=â211) in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), the degree and length of stenosis and plaque surface irregularity were assessed on baseline intraarterial angiography. Outcome measures were stroke or death occurring between randomization and 30 days after treatment, and ipsilateral stroke and restenosis â„50% during follow-up. RESULTS: Carotid stenosis longer than 0.65 times the common carotid artery diameter was associated with increased risk of peri-procedural stroke or death after both endovascular treatment [odds ratio 2.79 (1.17-6.65), Pâ=â0.02] and carotid endarterectomy [2.43 (1.03-5.73), Pâ=â0.04], and with increased long-term risk of restenosis in endovascular treatment [hazard ratio 1.68 (1.12-2.53), Pâ=â0.01]. The excess in restenosis after endovascular treatment compared with carotid endarterectomy was significantly greater in patients with long stenosis than with short stenosis at baseline (interaction Pâ=â0.003). Results remained significant after multivariate adjustment. No associations were found for degree of stenosis and plaque surface.
CONCLUSIONS: Increasing stenosis length is an independent risk factor for peri-procedural stroke or death in endovascular treatment and carotid endarterectomy, without favoring one treatment over the other. However, the excess restenosis rate after endovascular treatment compared with carotid endarterectomy increases with longer stenosis at baseline. Stenosis length merits further investigation in carotid revascularisation trials
The Cosmic Infrared Background Experiment (CIBER): The Wide-Field Imagers
We have developed and characterized an imaging instrument to measure the
spatial properties of the diffuse near-infrared extragalactic background light
in a search for fluctuations from z > 6 galaxies during the epoch of
reionization. The instrument is part of the Cosmic Infrared Background
Experiment (CIBER), designed to observe the extragalactic background light
above the Earth's atmosphere during a suborbital sounding rocket flight. The
imaging instrument incorporates a 2x2 degree field of view, to measure
fluctuations over the predicted peak of the spatial power spectrum at 10
arcminutes, and 7"x7" pixels, to remove lower redshift galaxies to a depth
sufficient to reduce the low-redshift galaxy clustering foreground below
instrumental sensitivity. The imaging instrument employs two cameras with
\Delta \lambda / \lambda ~0.5 bandpasses centered at 1.1 and 1.6 microns to
spectrally discriminate reionization extragalactic background fluctuations from
local foreground fluctuations. CIBER operates at wavelengths where the
electromagnetic spectrum of the reionization extragalactic background is
thought to peak, and complements fluctuations measurements by AKARI and Spitzer
at longer wavelengths. We have characterized the instrument in the laboratory,
including measurements of the sensitivity, flat-field response, stray light
performance, and noise properties. Several modifications were made to the
instrument following a first flight in 2009 February. The instrument performed
to specifications in subsequent flights in 2010 July and 2012 March, and the
scientific data are now being analyzed.Comment: 16 Pages, 16 figures, submitted to ApJS February 13 2012; accepted
June 20 2012 as part of CIBER Instrument Special Issu
H-Atlas: The cosmic abundance of dust from the far-infrared background power spectrum
We present a measurement of the angular power spectrum of the cosmic far-infrared background
(CFIRB) anisotropies in one of the extragalactic fields of the Herschel Astrophysical Terahertz Large
Area Survey (H-ATLAS) at 250, 350 and 500 ÎŒm bands. Consistent with recent measurements of
the CFIRB power spectrum in Herschel-SPIRE maps, we confirm the existence of a clear one-halo
term of galaxy clustering on arcminute angular scales with large-scale two-halo term of clustering
at 30 arcminutes to angular scales of a few degrees. The power spectrum at the largest angular
scales, especially at 250 ÎŒm, is contaminated by the Galactic cirrus. The angular power spectrum
is modeled using a conditional luminosity function approach to describe the spatial distribution of
unresolved galaxies that make up the bulk of the CFIRB.Web of Scienc
Reward devaluation disrupts latent inhibition in fear conditioning
Three experiments explored the link between
reward shifts and latent inhibition (LI). Using consummatory
procedures, rewards were either downshifted
from 32% to 4% sucrose (Experiments 1â2), or
upshifted from 4% to 32% sucrose (Experiment 3). In
both cases, appropriate unshifted controls were also included.
LI was implemented in terms of fear conditioning
involving a single tone-shock pairing after extensive
tone-only preexposure. Nonpreexposed controls were also
included. Experiment 1 demonstrated a typical LI effect
(i.e., disruption of fear conditioning after preexposure to the
tone) in animals previously exposed only to 4% sucrose.
However, the LI effect was eliminated by preexposure to a
32%-to-4% sucrose devaluation. Experiment 2 replicated
this effect when the LI protocol was administered immediately
after the reward devaluation event. However, LI was
restored when preexposure was administered after a 60-
min retention interval. Finally, Experiment 3 showed that
a reward upshift did not affect LI. These results point to a
significant role of negative emotion related to reward devaluation
in the enhancement of stimulus processing despite
extensive nonreinforced preexposure experience
H-ATLAS/GAMA: magnification bias tomography. Astrophysical constraints above ~1 arcmin
An unambiguous manifestation of the magnification bias is the cross-correlation between two source samples with non-overlapping redshift distributions. In this work we measure and study the cross-correlation signal between a foreground sample of GAMA galaxies with spectroscopic redshifts in the range 0.2<z<0.8, and a background sample of H-ATLAS galaxies with photometric redshifts gsim1.2. It constitutes a substantial improvement over the cross-correlation measurements made by Gonzalez-Nuevo et al. (2014) with updated catalogues and wider area (with S/Ngsim 5 below 10 arcmin and reaching S/N~ 20 below 30 arcsec). The better statistics allow us to split the sample in different redshift bins and to perform a tomographic analysis (with S/Ngsim 3 below 10 arcmin and reaching S/N~ 15 below 30 arcsec). Moreover, we implement a halo model to extract astrophysical information about the background galaxies and the deflectors that are producing the lensing link between the foreground (lenses) and background (sources) samples. In the case of the sources, we find typical mass values in agreement with previous studies: a minimum halo mass to host a central galaxy, Mmin~ 1012.26 Mâ, and a pivot halo mass to have at least one sub-halo satellite, M1~ 1012.84 Mâ. However, the lenses are massive galaxies or even galaxy groups/clusters, with minimum mass of Mminlens~ 1013.06 Mâ. Above a mass of M1lens~ 1014.57 Mâ they contain at least one additional satellite galaxy which contributes to the lensing effect. The tomographic analysis shows that, while M1lens is almost redshift independent, there is a clear evolution of increase Mminlens with redshift in agreement with theoretical estimations. Finally, the halo modeling allows us to identify a strong lensing contribution to the cross-correlation for angular scales below 30 arcsec. This interpretation is supported by the results of basic but effective simulations
Hamlet Without the Prince of Denmark: Relationship Banking and Conditionality Lending in the London Market for Foreign Government Debt, 1815-1913
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