3,349 research outputs found
Can the quality of social research on ethnicity be improved through the introduction of guidance? Findings from a research commissioning pilot exercise
As the volume of UK social research addressing ethnicity grows, so too do concerns regarding the ethical and scientific rigour of this research domain and its potential to do more harm than good. The establishment of standards and principles and the introduction of guidance documents at critical points within the research cycle might be one way to enhance the quality of such research. This article reports the findings from the piloting of a guidance document within the research commissioning process of a major funder of UK social research. The guidance document was positively received by researchers, the majority of whom reported it to be comprehensible, relevant and potentially useful in improving the quality of research proposals. However, a review of the submitted proposals suggested the guidance had had little impact on practice. While guidance may have a role to play, it will need to be strongly promoted by commissioners and other gatekeepers. Findings also suggest the possibility that guidance may discourage some researchers from engaging with ethnicity if it raises problems without solutions; highlighting the need for complementary investments in research capacity development in this area
Deep three-dimensional solid-state qubit arrays with long-lived spin coherence
Nitrogen-vacancy centers (NVCs) in diamond show promise for quantum computing, communication, and sensing. However, the best current method for entangling two NVCs requires that each one is in a separate cryostat, which is not scalable. We show that single NVCs can be laser written 6–15-µm deep inside of a diamond with spin coherence times that are an order of magnitude longer than previous laser-written NVCs and at least as long as naturally occurring NVCs. This depth is suitable for integration with solid immersion lenses or optical cavities and we present depth-dependent T2 measurements. 200 000 of these NVCs would fit into one diamond
Prior Helicobacter pylori infection ameliorates Salmonella typhimurium-induced colitis: Mucosal crosstalk between stomach and distal intestine
Background: Helicobacter pylori infection is associated with a lower risk of chronic autoimmune diseases including inflammatory bowel disease (IBD). H. pylori modulates the gastric immune response, decreasing the local inflammatory response to itself. In mice, chronic Salmonella typhimurium infection induces colitis similar to Crohn's disease, characterized by inflammation, which progresses toward fibrosis. The aim of this study was to determine whether prior H. pylori infection acts at a distance to modulate the immune response of S. typhimurium -induced colitis. Methods: Mice were infected with the mouse-adapted strain of H. pylori (SS1), followed by infection with S. typhimurium . The effect of H. pylori on colitis was determined by gross pathology, histopathology, cytokine response, and development of fibrosis in the cecum. Gastritis and systemic immune response was measured in response to infection. Results: H. pylori suppresses the Th17 response to S. typhimurium infection in the mouse cecum, but does not alter the Th2 or T-regulatory response or the development of fibrosis. H. pylori infection induces IL-10 in the mesenteric lymph nodes, suggesting an extragastric mechanism for immunomodulation. H. pylori / S. typhimurium coinfection decreases inflammation in both the cecum and the stomach. Conclusions: This study demonstrates a potential mechanism for the negative association between H. pylori and IBD in humans. H. pylori represses the lower gastrointestinal tract Th17 response to bacterially induced colitis via extragastric immunomodulatory effects, illustrating immunological crosstalk between the upper and lower gastrointestinal tract. (Inflamm Bowel Dis 2011;)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84386/1/21489_ftp.pd
Ultrafast nonlocal control of spontaneous emission
Solid-state cavity quantum electrodynamics systems will form scalable nodes
of future quantum networks, allowing the storage, processing and retrieval of
quantum bits, where a real-time control of the radiative interaction in the
cavity is required to achieve high efficiency. We demonstrate here the dynamic
molding of the vacuum field in a coupled-cavity system to achieve the ultrafast
nonlocal modulation of spontaneous emission of quantum dots in photonic crystal
cavities, on a timescale of ~200 ps, much faster than their natural radiative
lifetimes. This opens the way to the ultrafast control of semiconductor-based
cavity quantum electrodynamics systems for application in quantum interfaces
and to a new class of ultrafast lasers based on nano-photonic cavities.Comment: 15 pages, 4 figure
Casimir scaling as a test of QCD vacuum
Recent accurate measurements of static potentials between sources in various
representations of the gauge group SU(3) performed by G.Bali provide a crucial
test of the QCD vacuum models and different approaches to confinement. The
Casimir scaling of the potential observed for all measured distances implies
strong suppression of higher cumulant contributions. The consequences for the
instanton vacuum model and the spectrum of the QCD string are also discussed.Comment: LaTeX, 15 pages, 1 figur
Extinction Corrected Star Formation Rates Empirically Derived from Ultraviolet-Optical Colors
Using a sample of galaxies from the Sloan Digital Sky Survey spectroscopic
catalog with measured star-formation rates (SFRs) and ultraviolet (UV)
photometry from the GALEX Medium Imaging Survey, we derived empirical linear
correlations between the SFR to UV luminosity ratio and the UV-optical colors
of blue sequence galaxies. The relations provide a simple prescription to
correct UV data for dust attenuation that best reconciles the SFRs derived from
UV and emission line data. The method breaks down for the red sequence
population as well as for very blue galaxies such as the local ``supercompact''
UV luminous galaxies and the majority of high redshift Lyman Break Galaxies
which form a low attenuation sequence of their own.Comment: 20 pages, 11 figures, accepted for publication in the ApJS GALEX
special issu
The Star Formation and Extinction Co-Evolution of UV-Selected Galaxies over 0.05<z<1.2
We use a new stacking technique to obtain mean mid IR and far IR to far UV
flux ratios over the rest near-UV/near-IR color-magnitude diagram. We employ
COMBO-17 redshifts and COMBO-17 optical, GALEX far and near UV, Spitzer IRAC
and MIPS Mid IR photometry. This technique permits us to probe infrared excess
(IRX), the ratio of far IR to far UV luminosity, and specific star formation
rate (SSFR) and their co-evolution over two orders of magnitude of stellar mass
and redshift 0.1<z<1.2. We find that the SSFR and the characteristic mass (M_0)
above which the SSFR drops increase with redshift (downsizing). At any given
epoch, IRX is an increasing function of mass up to M_0. Above this mass IRX
falls, suggesting gas exhaustion. In a given mass bin below M_0 IRX increases
with time in a fashion consistent with enrichment. We interpret these trends
using a simple model with a Schmidt-Kennicutt law and extinction that tracks
gas density and enrichment. We find that the average IRX and SSFR follows a
galaxy age parameter which is determined mainly by the galaxy mass and time
since formation. We conclude that blue sequence galaxies have properties which
show simple, systematic trends with mass and time such as the steady build-up
of heavy elements in the interstellar media of evolving galaxies and the
exhaustion of gas in galaxies that are evolving off the blue sequence. The IRX
represents a tool for selecting galaxies at various stages of evolution.Comment: Accepted for publication in GALEX Special Ap.J.Suppl., December, 200
Ultraviolet through Infrared Spectral Energy Distributions from 1000 SDSS Galaxies: Dust Attenuation
The meaningful comparison of models of galaxy evolution to observations is
critically dependent on the accurate treatment of dust attenuation. To
investigate dust absorption and emission in galaxies we have assembled a sample
of ~1000 galaxies with ultraviolet (UV) through infrared (IR) photometry from
GALEX, SDSS, and Spitzer and optical spectroscopy from SDSS. The ratio of IR to
UV emission (IRX) is used to constrain the dust attenuation in galaxies. We use
the 4000A break as a robust and useful, although coarse, indicator of star
formation history (SFH). We examine the relationship between IRX and the UV
spectral slope (a common attenuation indicator at high-redshift) and find
little dependence of the scatter on 4000A break strength. We construct average
UV through far-IR spectral energy distributions (SEDs) for different ranges of
IRX, 4000A break strength, and stellar mass (M_*) to show the variation of the
entire SED with these parameters. When binned simultaneously by IRX, 4000A
break strength, and M_* these SEDs allow us to determine a low resolution
average attenuation curve for different ranges of M_*. The attenuation curves
thus derived are consistent with a lambda^{-0.7} attenuation law, and we find
no significant variations with M_*. Finally, we show the relationship between
IRX and the global stellar mass surface density and gas-phase-metallicity.
Among star forming galaxies we find a strong correlation between IRX and
stellar mass surface density, even at constant metallicity, a result that is
closely linked to the well-known correlation between IRX and star-formation
rate.Comment: 12 pages, 8 figures, 2 tables, appearing in the Dec 2007 GALEX
special issue of ApJ Supp (29 papers
A wider Europe? The view from Russia, Belarus and Ukraine
On the evidence of national surveys conducted between 2000 and 2006, there is a declining sense of European self-identity in the three Slavic post-Soviet republics of Russia, Belarus and Ukraine. Attitudes towards the European Union and the possibility of membership are broadly supportive, but with a substantial proportion who find it difficult to express a view, and substantial proportions are poorly informed in comparison with the general public in EU member or prospective member countries. Those who are better informed are more likely to favour EU membership and vice versa. Generally, socioeconomic characteristics (except for age and region) are relatively poor predictors of support for EU membership as compared with attitudinal variables. But ‘Europeanness’ should not be seen as a given, and much will depend on whether EU member countries emphasize what is common to east and west or establish ‘new dividing lines’ in place of those of the cold war
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