770 research outputs found
What are elections for? conferring the median mandate
Democracy is often described as a system in which a majority of electors choose one out of a number of competing parties to form a government and carry out its programme. Unfortunately, spontaneous majorities rarely form in support of one party. We generalize from a 'government' to a 'median' mandate, in which the median elector chooses the pivotal party in parliament, which then translates his or her preferences into public policy. To check this we investigate how accurately parliaments and governments represent the left-right position of the median voter in each of twenty parliamentary democracies. Distortions depend on the type of electoral arrangement, being relatively smaller under proportional representation than under single-member districts. Distortions do not equate to biased representation, however. Once we consider how distortions at one step or one time are compensated by distortions in the opposite direction at another, overall representation of the median voter position is reasonably accurate
Tuning biexciton binding and anti-binding in core/shell quantum dots
We use a path integral quantum Monte Carlo method to simulate excitons and
biexcitons in core shell nanocrystals with Type-I, II and quasi-Type II band
alignments. Quantum Monte Carlo techniques allow for all quantum correlations
to be included when determining the thermal ground state, thus producing
accurate predictions of biexciton binding. These subtle quantum correlations
are found to cause the biexciton to be binding with Type-I carrier localization
and strongly anti-binding with Type-II carrier localization, in agreement with
experiment for both core shell nanocrystals and dot in rod nanocrystal
structures. Simple treatments based on perturbative approaches are shown to
miss this important transition in the biexciton binding. Understanding these
correlations offers prospects to engineer strong biexciton anti-binding which
is crucial to the design of nanocrystals for single exciton lasing
applications.Comment: 10 pages, 11 figure
The surface-state of the topological insulator BiSe revealed by cyclotron resonance
To date transport measurements of topological insulators have been dominated
by the conductivity of the bulk, leading to substantial difficulties in
resolving the properties of the surface. To this end, we use high magnetic
field, rf- and microwave-spectroscopy to selectively couple to the surface
conductivity of BiSe at high frequency. In the frequency range of a few
GHz we observe a crossover from quantum oscillations indicative of a small 3D
Fermi surface, to cyclotron resonance indicative of a 2D surface state
Review of research on migration influences and implications for population dynamics in the wider South East
The Wider South East (WSE) is a large, diverse, dynamic, well networked and polycentric region – although with over a third of its population in one central conurbation. The effect of this combination of characteristics is to give it a highly integrated migration system, with sub-regions occupying different roles and to varying degrees of dynamism, but interacting with the other sub-regions and responding to some shared external factors - in ways that need to be better understood
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Magnetoresistance Scaling Reveals Symmetries of the Strongly Correlated Dynamics in BaFe_{2}(As_{1-x}P_{x})_{2}.
The phenomenon of T-linear resistivity commonly observed in a number of strange metals has been widely seen as evidence for the breakdown of the quasiparticle picture of metals. This study shows that a recently discovered H/T scaling relationship in the magnetoresistance of the strange metal BaFe_{2}(As_{1-x}P_{x})_{2} is independent of the relative orientations of current and magnetic field. Rather, its magnitude and form depend only on the orientation of the magnetic field with respect to a single crystallographic axis: the direction perpendicular to the magnetic iron layers. This finding suggests that the magnetotransport scaling does not originate from the conventional averaging or orbital velocity of quasiparticles as they traverse a Fermi surface, but rather from dissipation arising from two-dimensional correlations
Marketing and clinical trials: a case study.
BACKGROUND: Publicly funded clinical trials require a substantial commitment of time and money. To ensure that sufficient numbers of patients are recruited it is essential that they address important questions in a rigorous manner and are managed well, adopting effective marketing strategies. METHODS: Using methods of analysis drawn from management studies, this paper presents a structured assessment framework or reference model, derived from a case analysis of the MRC's CRASH trial, of 12 factors that may affect the success of the marketing and sales activities associated with clinical trials. RESULTS: The case study demonstrates that trials need various categories of people to buy in - hence, to be successful, trialists must embrace marketing strategies to some extent. CONCLUSION: The performance of future clinical trials could be enhanced if trialists routinely considered these factors
Caledonian hot zone magmatism in the “Newer Granites”: insight from the Cluanie and Clunes plutons, Northern Scottish Highlands
Scottish “Newer” Granites record the evolution of the Caledonides resulting from Iapetus subduction and slab breakoff during the Silurian-Devonian Scandian Orogeny, but relationships between geodynamics, petrogenesis and emplacement are incomplete. Laser ablation U-Pb results from magmatic zircons at the Cluanie Pluton (Northern Highlands) identify clusters of concordant Silurian data points. A cluster with a weighted mean 206Pb/238U age of 431.6 ± 1.3 Ma (2 confidence interval, n = 6) records emplacement whilst older points (clustered at 441.8 ± 2.3 Ma, n = 9) record deep crustal hot zone magmatism prior to ascent. The Cluanie Pluton, and its neighbour the ∼428 Ma Clunes tonalite, have adakite-like high Na, Sr/Y, La/Yb and low Mg, Ni and Cr characteristics, and lack mafic facies common in other “Newer Granites”. These geochemical signatures indicate the tapping of batches of homogenised, evolved magma from the deeper crust. The emplacement age of the Cluanie Pluton confirms volumetrically modest subduction-related magmatism occurred beneath the Northern Highlands before slab breakoff, probably as a result of crustal thickening during the ∼450 Ma Grampian 2 event. Extensive new in-situ geochemical-geochronological studies for this terrane may further substantiate the deep crustal hot zone model and the association between Caledonian magmatism and potentially metallogenesis. The term “Newer Granites” is outdated as it ignores the demonstrated relationships between magmatism, Scandian orogenesis and slab breakoff. Hence, “Caledonian intrusions” would be a more appropriate generic term to cover those bodies related to either Iapetus subduction or to slab breakoff
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