290 research outputs found
BMP signals: Mediated by stroma or thymocytes?
This is an invited comment on the paper by Hager-Theodorides AL, et al. Cell Cycle 2014; 13:324â33; PMID:24240189; http://dx.doi.org/10.4161/cc.27118 which is published in the same journa
A catalogue of absorption-line systems in QSO spectra
We present a new catalog of absprption-line systems identified in the quasar
spectra. It contains data on 821 QSOs and 8558 absorption systems comprizing
16139 absorption lines with measured redshifts in the QSO spectra. The catalog
includes absorption-line systems consisting of lines of heavy elements, lines
of neutral hydrogen, Lyman limit systems, damped Ly\alpha absorption systems,
and broad absorption-line systems. The catalog is available in electronic form
at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/412/707 and at
www.ioffe.ru/astro/QC. Using the data of the present catalog we also discuss
redshift distributions of absorption-line systems.Comment: 3 pages with 1 postscript figur
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
A first look at cataclysmic variable stars from the 2dF QSO survey
The 2dF QSO survey is a spectroscopic survey of 48,000 point-sources selected
by colour with magnitudes in the range 18.35 < B < 20.95. Amongst QSOs, white
dwarfs, narrow-line galaxies and other objects are some cataclysmic variables
(CVs). This survey should be sensitive to intrinsically faint CVs. In the
standard picture of CV evolution, these form the majority of the CV population.
We present the spectra of 6 CVs from this survey. Four have the spectra of
dwarf novae and two are magnetic CVs. We present evidence that suggests that
the dwarf novae have period P < 2 h and are indeed intrinsically less luminous
than average. However, it is not clear yet whether these systems are present in
the large numbers predicted.Comment: 8 pages, 4 figures. Proceedings of the Goettingen conference on
Cataclysmic Variable Stars, Goettingen, August 200
Metal abundances and ionization conditions in a possibly dust-free damped Ly-alpha system at z=2.3
We have obtained a high resolution, high S/N UVES spectrum of the bright QSO
HE2243-6031 to analyze the damped Ly-alpha system (DLA) observed at z=2.33. The
metallicity of this system is 1/12 solar at a neutral hydrogen column density
of log N(HI)=20.7. From the observed ratios [Zn/Cr]=-0.01+/-0.05 and
[S/Si]=-0.06+/-0.03$ we conclude that dust is very likely absent from the ISM
of this protogalaxy. We observe an enhancement of the alpha/Fe-peak ratios of
+0.2 dex for various elements, a marked odd-even effect in Mn, and a strong
underabundance of N relative to Si and S, [N/Si,S]=-1 at [Si/H]=-0.86. All of
these ratios support an environment that is in an early evolutionary stage,
where the onset of star formation has begun only shortly before the DLA was
observed. We also perform a cloud-by-cloud analysis -- without precedent at
high redshift -- and find a tight correlation of all low-ionization species
with respect to FeII extending over 2.5 orders of magnitude in N(FeII). We
interpret this trend as being due to homogeneous physical conditions (very mild
ionization effects, common dust-destruction histories, same chemical
composition) and propose that this line of sight encounters absorbing clouds
that share a common environment. In addition, photoionization models show that
these single clouds are shielded from the external ionizing radiation, so the
fraction of ionized gas is small and, except for argon, does not influence the
measured metal abundances. The observed AlIII/low-ion ratios suggest the mildly
ionized gas occurs in shells surrounding neutral cores of AlII.Comment: To be published in A&
A bone grease processing station at the Mitchell Prehistoric Indian Village: archaeological evidence for the exploitation of bone fats
© Association for Environmental Archaeology 2015. Author's accepted manuscript version deposited in accordance with SHERPA RoMEO guidelines. The definitive version is available at http://www.maneyonline.com/doi/abs/10.1179/1749631414Y.0000000035.Recent excavations at the Mitchell Prehistoric Indian Village, an Initial Middle Missouri site in Mitchell, South Dakota have revealed a large, clay-lined feature filled with fractured and fragmented bison bones. Fracture and fragmentation analysis, along with taphonomic evidence, suggests that the bones preserved within the feature represent evidence of prehistoric bone marrow and bone grease exploitation. Further, the character of the feature suggests that it served as a bone grease processing station. Bone fat exploitation is an activity that is frequently cited as a causal explanation for the nature of many fractured and fragmented bone assemblages in prehistory, and zooarchaeological assemblages have frequently been studied as evidence of bone fat exploitation. The Mitchell example provides some of the first direct, in-situ archaeological evidence of a bone grease processing feature, and this interpretation is sustained by substantial analytical evidence suggesting bone fat exploitation. This new evidence provides a clearer concept of the nature of bone fat exploitation in prehistory as well as an indication of the scale and degree to which bone grease exploitation occurred at the Mitchell site. Finally, this research demonstrates the importance of careful zooarchaeological and taphonomic analysis for the interpretation of both artifactual remains as well as archaeological features
Further Evidence for Cosmological Evolution of the Fine Structure Constant
We describe the results of a search for time variability of the fine
structure constant, alpha, using absorption systems in the spectra of distant
quasars. Three large optical datasets and two 21cm/mm absorption systems
provide four independent samples, spanning 23% to 87% of the age of the
universe. Each sample yields a smaller alpha in the past and the optical sample
shows a 4-sigma deviation: da/a = -0.72 +/- 0.18 x 10^{-5} over the redshift
range 0.5 < z < 3.5. We find no systematic effects which can explain our
results. The only potentially significant systematic effects push da/a towards
positive values, i.e. our results would become more significant were we to
correct for them.Comment: 5 pages, 1 figure. Published in Phys. Rev. Lett. Small changes to
discussion, added an acknowledgement and a referenc
Inventing the Neolithic? Putting evidence-based interpretation back into the study of faunal remains from causewayed enclosures.
ArticleThis is an Accepted Manuscript of an article published by Taylor & Francis in World Archaeology on 2015, available online: http://wwww.tandfonline.com/10.1080/00438243.2015.1072476The paper argues that our current understanding of the animal bones from causewayed enclosure sites in Britain is flawed. During the 1980-90s, a number of key interpretations, still frequently espoused, were based more upon anecdote and theory-driven assertion than on empirical evidence. An example is that evidence of bone processing (butchery and bone fracture) does not feature heavily in the faunal record from causewayed enclosures. Using data from the sites of Etton and Staines, this view must now be questioned. Both butchery and peri-mortem bone fracture are present in these assemblages in substantial quantities. These sites are compared with Ludwinowo 7, a Linearbandkeramik settlement site in Poland and there are considerable similarities between the three different sites. This suggests possibility that the broader economic utility of animal bone assemblages at causewayed enclosures has been underestimated, having been, up to now, regarded as ânot indicative of domestic settlementâ
Modelling the impacts of agricultural management practices on river water quality in Eastern England
Agricultural diffuse water pollution remains a notable global pressure on water quality, posing risks to aquatic ecosystems, human health and water resources and as a result legislation has been introduced in many parts of the world to protect water bodies. Due to their efficiency and cost-effectiveness, water quality models have been increasingly applied to catchments as Decision Support Tools (DSTs) to identify mitigation options that can be introduced to reduce agricultural diffuse water pollution and improve water quality. In this study, the Soil and Water Assessment Tool (SWAT) was applied to the River Wensum catchment in eastern England with the aim of quantifying the long-term impacts of potential changes to agricultural management practices on river water quality. Calibration and validation were successfully performed at a daily time-step against observations of discharge, nitrate and total phosphorus obtained from high-frequency water quality monitoring within the Blackwater sub-catchment, covering an area of 19.6 km2. A variety of mitigation options were identified and modelled, both singly and in combination, and their long-term effects on nitrate and total phosphorus losses were quantified together with the 95% uncertainty range of model predictions. Results showed that introducing a red clover cover crop to the crop rotation scheme applied within the catchment reduced nitrate losses by 19.6%. Buffer strips of 2 m and 6 m width represented the most effective options to reduce total phosphorus losses, achieving reductions of 12.2% and 16.9%, respectively. This is one of the first studies to quantify the impacts of agricultural mitigation options on long-term water quality for nitrate and total phosphorus at a daily resolution, in addition to providing an estimate of the uncertainties of those impacts. The results highlighted the need to consider multiple pollutants, the degree of uncertainty associated with model predictions and the risk of unintended pollutant impacts when evaluating the effectiveness of mitigation options, and showed that high-frequency water quality datasets can be applied to robustly calibrate water quality models, creating DSTs that are more effective and reliable
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