1,348 research outputs found
Government ideology and international migration
We provide the first empirical evidence that differences in government ideology play an
important role in the choice of cross-border migration destinations. In absence of first-hand
experience, immigrants rely on information about the political landscape of the origin and host
countries to form expectations about the context of reception in the host society. We use
data on bilateral migration and government ideology for 36 OECD countries between 1990 and
2016. Our analysis shows that bilateral migration flows are higher when the government at the
destination is more left-wing than the government at the origin, especially when we consider
proximate countries
Experimental evidence of new tetragonal polymorphs of silicon formed through ultrafast laser-induced confined microexplosion
Ordinary materials can transform into novel phases at extraordinary high pressure and temperature. The recently developed method of ultrashort laser-induced confined microexplosions initiates a non-equilibrium disordered plasma state. Ultra-high quenching rates overcome kinetic barriers to the formation of new metastable phases, which are preserved in the surrounding pristine crystal for subsequent exploitation. Here we demonstrate that confined microexplosions in silicon produce several metastable end phases. Comparison with an ab initio random structure search reveals six energetically competitive potential phases, four tetragonal and two monoclinic structures. We show the presence of bt8 and st12, which have been predicted theoretically previously, but have not been observed in nature or in laboratory experiments. In addition, the presence of the as yet unidentified silicon phase, Si-VIII and two of our other predicted tetragonal phases are highly likely within laser-affected zones. These findings may pave the way for new materials with novel and exotic properties
A first handbook of the roots of English by Norman Bird: Lapine Education and Language Services Ltd, 1990
Book Reviewpublished_or_final_versio
Electron spectroscopy of carbon materials: Experiment and theory
We present a comparative spectroscopic study of carbon as graphite, diamond and C60 using C1s K-edge electron energy-loss spectroscopy (EELS), X-ray emission spectroscopy, and theoretical modelling. The first principles calculations of these spectra are obtained in the local density approximation using a self-consistent Gaussian basis pseudo-potential method. Calculated spectra show excellent agreement with experiment and are able to discriminate not only between various carbon hybridisations but also local variation in environment. Core-hole effects on the calculated spectra are also investigated. For the first time, the EEL spectrum of carbyne is calculated
Post-aragonite phases of CaCO at lower mantle pressures
The stability, structure and properties of carbonate minerals at lower mantle
conditions has significant impact on our understanding of the global carbon
cycle and the composition of the interior of the Earth. In recent years, there
has been significant interest in the behavior of carbonates at lower mantle
conditions, specifically in their carbon hybridization, which has relevance for
the storage of carbon within the deep mantle. Using high-pressure synchrotron
X-ray diffraction in a diamond anvil cell coupled with direct laser heating of
CaCO using a CO laser, we identify a crystalline phase of the
material above 40 GPa corresponding to a lower mantle depth of around 1,000
km which has first been predicted by \textit{ab initio} structure
predictions. The observed carbon hybridized species at 40 GPa is
monoclinic with symmetry and is stable up to 50 GPa, above which it
transforms into a structure which cannot be indexed by existing known phases. A
combination of \textit{ab initio} random structure search (AIRSS) and
quasi-harmonic approximation (QHA) calculations are used to re-explore the
relative phase stabilities of the rich phase diagram of CaCO. Nudged
elastic band (NEB) calculations are used to investigate the reaction mechanisms
between relevant crystal phases of CaCO and we postulate that the mineral
is capable of undergoing - hybridization change purely in the
structure forgoing the accepted post-aragonite structure.Comment: 12 pages, 8 figure
Did terrorism affect voting in the Brexit referendum?
We contribute to the recent research on Brexit and public opinion formation by contending that the determinants of the referendum results should be evaluated against the background of wider public security concerns. Terrorism has long been regarded as a top concern by the British public, more than in any other European country. Terrorist attacks on UK soil raised voters’ awareness of security issues and their saliency in the context of an EU referendum. We find that locations affected by terrorist violence in their proximity exhibit an increase in the share of pro-Remain votes, particularly for more sensational attacks. Using individual-level data, we show
that in the aftermath of terrorist attacks, citizens are more likely to reconsider the security risks involved in leaving the EU
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