4,202 research outputs found
Spectral Properties From Lyman-alpha to H-alpha For An Essentially Complete Sample of Quasars I: Data
We have obtained quasi-simultaneous ultraviolet-optical spectra for 22 out of
23 quasars in the complete PG-X-ray sample with redshift, z<0.4, and M_B<-23.
The spectra cover rest-frame wavelengths from at least Lyman-alpha to H-alpha.
Here we provide a detailed description of the data, including careful
spectrophotometry and redshift determination. We also present direct
measurements of the continua, strong emission lines and features, including
Lyman-alpha, SiIV+OIV], CIV, CIII], SiIII], MgII, H-beta, [OIII],
He5876+NaI5890,5896, H-alpha, and blended iron emission in the UV and optical.
The widths, asymmetries and velocity shifts of profiles of strong emission
lines show that CIV and Lyman-alpha are very different from H-beta and H-alpha.
This suggests that the motion of the broad line region is related to the
ionization structure, but the data appears not agree with the radially
stratified ionization structure supported by reverberation mapping studies, and
therefore suggest that outflows contribute additional velocity components to
the broad emission line profiles.Comment: 42 pages, 10 figures, 13 tables. Accepted by AJ. Supplemental figures
not included. Full version available at
http://physics.uwyo.edu/~shang/pgxpaper/ShangPaper.pd
Inelastic neutron scattering studies of the quantum frustrated magnet clinoatacamite, -Cu2(OD)3Cl, a proposed valence bond solid (VBS)
The frustrated magnet clinoatacamite, -Cu(OH)Cl, is
attracting a lot of interest after suggestions that at low temperature it forms
an exotic quantum state termed a Valence Bond Solid (VBS) made from dimerised
Cu () spins.\cite{Lee_clinoatacamite} Key to the arguments
surrounding this proposal were suggestions that the kagom\'e planes in the
magnetic pyrochlore lattice of clinoatacamite are only weakly coupled, causing
the system to behave as a quasi-2-dimensional magnet. This was reasoned from
the near 95 angles made at the bridging oxygens that mediate exchange
between the Cu ions that link the kagom\'e planes.
Recent work pointed out that this exchange model is inappropriate for
-Cu(OH)Cl, where the oxygen is present as a
-OH.\cite{Wills_JPC} Further, it used symmetry calculations and neutron
powder diffraction to show that the low temperature magnetic structure (
K) was canted and involved significant spin ordering on all the Cu
spins, which is incompatible with the interpretation of simultaneous VBS and
N\'eel ordering. Correspondingly, clinoatacamite is best considered a distorted
pyrochlore magnet. In this report we show detailed inelastic neutron scattering
spectra and revisit the responses of this frustrated quantum magnet.Comment: Proceedings of The International Conference on Highly Frustrated
Magnetism 2008 (HFM2008
Toward Perfection: Kapellasite, Cu3Zn(OH)6Cl2, a New Model S = 1/2 Kagome Antiferromagnet
The search for the resonating valence bond (RVB) state continues to underpin
many areas of condensed matter research. The RVB is made from the dimerisation
of spins on different sites into fluctuating singlets, and was proposed by
Anderson to be the reference state from which the transition to BCS
superconductivity occurs. Little is known about the state experimentally, due
to the scarcity of model materials. Theoretical work has put forward the S =
1/2 kagome antiferromagnet (KAFM) as a good candidate for the realization of
the RVB state. In this paper we introduce a new model system, the S = 1/2 KAFM
Kapellasite, Cu3Zn(OH)6Cl2. We show that its crystal structure is a good
approximation to a 2-dimensional kagome antiferromagnet and that susceptibility
data indicate a collapse of the magnetic moment below T = 25 K that is
compatible with the spins condensing into the non-magnetic RVB state.Comment: Communication, 3 pages, 3 figure
In-work poverty and the living wage in the United Kingdom: a geographical perspective
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordDrawing on new empirical data from the UK, this paper takes a geographical perspective on the living wage. It highlights the extent to which the living wage is a geographical intervention to tackle in-work poverty that reflects the cost of living and social reproduction in a particular geographical area, aiming to set a new minimum across the labour market. The paper further argues that there is a scalar geography to understanding the impact of the campaign and the arguments made to defend it. Whereas the living wage has major cost implications for the particular employers and clients affected – increasing wages by approximately 30 per cent above the national minimum wage – it also has the potential to reduce costs across the wider society. There is thus a scalar dimension to making the argument for a living wage that can help to inform the future direction of the campaign. The paper concludes by raising some wider questions about the contribution that geographers can make to the study and alleviation of poverty.We are very grateful to Trust for London for fundin
The London living wage and in-work poverty reduction: Impacts on employers and workers
This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this recordIn the UK, a campaign for the living wage has emerged as a civil society initiative to reduce in-work poverty. This article reports empirical evidence from a study of employers adopting the London Living Wage and the benefits from this intervention, as reported by their workers. Implementation strategies to cover higher wage costs varied, from clients meeting full costs, to reduced employer profit, to reductions in hours and employment. There were strong substitution effects from low to higher qualified workers. The evidence suggests that while there were worker benefits from the living wage, they were not automatic, as higher wage rates did not necessarily translate into higher incomes due to variations in hours of work. Workers reported more in-work benefits, than family or financial benefits. In-work poverty reduction was limited by large concentrations of part-time living wage jobs with few hours, small income increases and the rising costs of living.The author(s) received no financial support for the research, authorship, and/or
publication of this article.This research was partly funded by Trust for Londo
Design specification for LARSYS procedure 1
There are no author-identified significant results in this report
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