15,381 research outputs found
ISM composition through X-ray spectroscopy of LMXBs
The diffuse interstellar medium (ISM) is an integral part of the evolution of
the entire Galaxy. Metals are produced by stars and their abundances are the
direct testimony of the history of stellar evolution. However, the interstellar
dust composition is not well known and the total abundances are yet to be
accurately determined. We probe ISM dust composition, total abundances, and
abundance gradients through the study of interstellar absorption features in
the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs).
We use high-quality grating spectra of nine LMXBs taken with XMM-Newton. We
measure the column densities of O, Ne, Mg, and Fe with an empirical model and
estimate the Galactic abundance gradients. The column densities of the neutral
gas species are in agreement with those found in the literature. Solids are a
significant reservoir of metals like oxygen and iron. Respectively, 15-25 % and
65-90 % of the total amount of O I and Fe I is found in dust. The dust amount
and mixture seem to be consistent along all the lines-of-sight (LOS). Our
estimates of abundance gradients and predictions of local interstellar
abundances are in agreement with those measured at longer wavelengths. Our work
shows that X-ray spectroscopy is a very powerful method to probe the ISM. For
instance, on a large scale the ISM appears to be chemically homogeneous showing
similar gas ionization ratios and dust mixtures. The agreement between the
abundances of the ISM and the stellar objects suggests that the local Galaxy is
also chemically homogeneous.Comment: 13 pages, 10 figures, 5 tables, accepted to A&
Deuteron Magnetic Quadrupole Moment From Chiral Effective Field Theory
We calculate the magnetic quadrupole moment (MQM) of the deuteron at leading
order in the systematic expansion provided by chiral effective field theory. We
take into account parity and time-reversal violation which, at the quark-gluon
level, results from the QCD vacuum angle and dimension-six operators that
originate from physics beyond the Standard Model. We show that the deuteron MQM
can be expressed in terms of five low-energy constants that appear in the
parity- and time-reversal-violating nuclear potential and electromagnetic
current, four of which also contribute to the electric dipole moments of light
nuclei. We conclude that the deuteron MQM has an enhanced sensitivity to the
QCD vacuum angle and that its measurement would be complementary to the
proposed measurements of light-nuclear EDMs
The impact of the Article 50 talks on the EU:Risk aversion and the prospects for further EU disintegration
This article explores why there was no domino effect after Brexit and reflects on what this means for the health of European integration. It shows how the UK responded to the uncertainty surrounding the Article 50 talks by testing EU unity, prompting both sides to discuss a no-deal outcome. Evidence from Eurobarometer surveys demonstrates that attachment to the EU strengthened markedly during Brexit talks in the four countries considered most likely to flirt with leaving the EU. Hence Brexit changed the benchmarking process surrounding citizens’ evaluation of the prospects of getting a better deal outside the EU. Risk aversion thus explains the lack of a Brexit domino effect. However, the volatility of public opinion before and after the Article 50 talks, combined with the weaker increase in support over the EU as a whole, means there is no room for complacency over the future prospects of disintegration
Valence bond glass on an fcc lattice in the double perovskite Ba2YMoO6
Peer reviewedPublisher PD
Time trends in educational inequalities in cancer mortality in Colombia, 1998-2012
Objectives: To evaluate trends in premature cancer mortality in Colombia by educational level in three periods: 1998-2002 with low healthcare insurance coverage, 2003-2007 with rapidly increasing coverage and finally 2008-2012 with almost universal coverage (2008-2012). Setting: Colombian population-based, national secondary mortality data. Participants: We included all (n=188 091) cancer deaths occurring in the age group 20-64 years between 1998 and 2012, excluding only cases with low levels of quality of registration (n=2902, 1.5%). Primary and secondary outcome measures: In this descriptive study, we linked mortality data of ages 20-64 years to census data to obtain age-standardised cancer mortality rates by educational level. Using Poisson regression, we modelled premature mortality by educational level estimating rate ratios (RR), relative index of inequality (RII) and the Slope Index of Inequality (SII). Results: Relative measures showed increased risks of dying among the lower educated compared to the highest educated; this tendency was stronger in women (RRprimary1.49; RRsecondary1.22, both p<0.0001) than in men (RRprimary 1.35; RRsecondary 1.11, both p<0.0001). In absolute terms (SII), cancer caused a difference per 100 000 deaths between the highest and lowest educated of 20.5 in males and 28.5 in females. RII was significantly higher among women and the younger age categories. RII decreased between the first and second periods; afterwards (2008-2012), it increased significantly back to their previous levels. Among women, no significant increases or declines in cancer mortality over time were observed in recent periods in the lowest educated group, whereas strong recent declines were observed in those with secondary education or higher. Conclusions: Educational inequalities in cancer mortality in Colombia are increasing in absolute and relative terms, and are concentrated in young age categories. This trend was not curbed by increases in healthcare insurance coverage. Policymakers should focus on improving equal access to prevention, early detection, diagnostic and treatment facilities
Inclusion of non-spherical components of the Pauli blocking operator in (p,p') reactions
We present the first calculations of proton elastic and inelastic scattering
in which the Pauli blocking operator contains the leading non-spherical
components as well as the usual spherical (angle-averaged) part. We develop a
formalism for including the contributions to the effective nucleon-nucleon
interaction from the resulting new G-matrix elements that extend the usual
two-nucleon spin structure and may not conserve angular momentum. We explore
the consequences of parity conservation, time reversal invariance, and
nucleon-nucleon antisymmetrization for the new effective interaction. Changes
to the calculated cross section and spin observables are small in the energy
range from 100 to 200 MeV.Comment: 24 pages, 4 figures, to be published in Physical Review
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