Zircon as a tracer of plumbing processes in an active magmatic system: insights from mingled magmas of the 2010 dome collapse, Montserrat, Lesser Antilles Arc, Caribbean

This project has received funding from the European Union's Hori-zon 2020 research and innovation programme under the Marie Skodowska-Curie grant agreement No. 749611 (JHS) . We also ac-knowledge funding from the Natural Environment Research Council Isotope Geoscience Facilities Steering Committee, grant IP-1746-1117 (JB) . The work has been financially supported by the Spanish grant CGL 2017-84469-P (JHS) . Funding for open access charge: Universidad de Granada/CBUA. Alexander Varychev at the University of Heidelberg, Germany, and Jeremy Rushton at the British Geological Survey, U.K., are thanked for help with analytical work. Jose Luis Macias is thanked for editorial handling. We are obliged to two anonymous reviewers for the time and effort they took to help us improve the clarity and rigour of our interpretations. 19Soufriere Hills Volcano, Montserrat, erupted from 1995 to 2010, with activity including dome growth, destructive pyroclastic density currents and Vulcanian explosions. Monitoring data, such as gas emissions, show the system is still in a state of unrest. The recent eruptions provide an opportunity to study, in real time, a complex subduction-related subvolcanic transaustal melt-mush reservoir, its magma fluxes, and the timing of crystal and melt storage prior to eruptive paroxysms. How and when mush destabilisation occurs prior to volcanic eruptions continues to be a question of intense debate. Evidence of mafic magma intrusion, a potential eruptive trigger, is preserved in enclaves with quenched and diffuse margins that are mingled with crystal-rich andesite. Here, in this first study of Soufriere Hills Volcano zircon, we report zircon ages and compositions for mafic-intermediate enclaves and host andesites from the most recent dome collapse in 2010 to place temporal constraints on magma reservoir processes. Zircon U-238-Th-230 ages disequilibrium crystallisation ages ranging between c. 2-250 ka constrain the longevity of the magmatic plumbing system. Uniform Hf isotopes, epsilon Hf 11.3 +/- 12 to 14.6 +/- 1.5, indicate invariant compositions that are typical for island arc magma sources. Zircon trace element concentrations and Ti-in-zircon crystallisation temperatures indicate crystallisation in isolated, small-volume, lenses with variable fractions of melt of heterogeneous compositions. We suggest amalgamation of assorted crystal cargoes from these lenses occurred prior to eruption during mush destabilisation triggered by mafic magma recharge. Zircon textures, on the other hand, shed light on recent centimetre-scale magma mingling immediately prior to eruption. Euhedral-subhedral zircon is preferentially preserved in or near quenched contacts of the least-evolved enclave and host andesite. By contrast, reheating of the andesite by the mafic magma recharge in the presence of zircon-undersaturated melts promoted zircon resorption. This led to the formation of subhedral-anhedral corroded zircon that is typical in the host andesite mush. Zircon thus reveals processes ranging from 100,000s of years of andesite storage to short-term partial destruction in response to transient heating and magma mixing events.European Commission 749611Natural Environment Research Council Isotope Geoscience Facilities Steering Committee IP-1746-1117Spanish Government CGL 2017-84469-PUniversidad de Granada/CBU

Oh, Jeremy Corbyn! Why did Labour Party membership soar after the 2015 general election?

This article investigates the remarkable surge in individual membership of the Labour Party after the general election of May 2015, particularly after Jeremy Corbyn was officially nominated as a candidate for the leadership in June of that year. Using both British Election Study and Party Members Project data, we explain the surge by focussing on the attitudinal, ideological and demographic characteristics of the members themselves. Findings suggest that, along with support for the leader and yearning for a new style of politics, feelings of relative deprivation played a significant part: many ‘left-behind’ voters (some well-educated, some less so) joined Labour for the first time when a candidate with a clearly radical profile appeared on the leadership ballot. Anti-capitalist and left-wing values mattered too, particularly for those former members who decided to return to the party

A novel approach for evaluating contact patterns and risk mitigation strategies for COVID-19 in English primary schools with application of structured expert judgement

Personal contacts drive COVID-19 infections. After being closed (23 March 2020) UK primary schools partially re-opened on 1 June 2020 with social distancing and new risk mitigation strategies. We conducted a structured expert elicitation of teachers to quantify primary school contact patterns and how contact rates changed upon re-opening with risk mitigation measures in place. These rates, with uncertainties, were determined using a performance-based algorithm. We report mean number of contacts per day for four cohorts within schools, with associated 90% confidence ranges. Prior to lockdown, younger children (Reception and Year 1) made 15 contacts per day [range 8.35] within school, older children (Year 6) 18 contacts [range 5.55], teaching staff 25 contacts [range 4.55] and non-classroom staff 11 contacts [range 2.27]. After re-opening, the mean number of contacts was reduced by 53% for young children, 62% for older children, 60% for classroom staff and 64% for other staff. Contacts between teaching and non-teaching staff reduced by 80%. The distributions of contacts per person are asymmetric with heavy tail reflecting a few individuals with high contact numbers. Questions on risk mitigation and supplementary structured interviews elucidated how new measures reduced daily contacts in-school and contribute to infection risk reduction

Party rules, party resources, and the politics of parliamentary democracies: how parties organize in the 21st Century

This article introduces the first findings of the Political Party Database (PPDB) project, a major survey of party organizations in parliamentary and semi-presidential democracies. The project’s first round of data covers 122 parties in 19 countries. In this paper we describe the scope of the database, then investigate what it tells us about contemporary party organization in these countries, focussing on parties’ resources, structures and internal decision-making. We examine organizational patterns by country and party family, and where possible we make temporal comparisons with older datasets. Our analyses suggest a remarkable coexistence of uniformity and diversity. In terms of the major organizational resources on which parties can draw, such as members, staff and finance, the new evidence largely confirms the continuation of trends identified in previous research: i.e., declining membership, but enhanced financial resources and more paid staff. We also find remarkable uniformity regarding the core architecture of party organizations. At the same time, however, we find substantial variation between countries and party families in terms of their internal processes, with particular regard to how internally democratic they are, and in the forms that this democratization takes

The democratic interface: technology, political organization, and diverging patterns of electoral representation

Democracies are experiencing historic disruptions affecting how people engage with core institutions such as the press, civil society organizations, parties, and elections. These processes of citizen interaction with institutions operate as a democratic interface shaping self-government and the quality of public life. The electoral dimension of the interface is important, as its operation can affect all others. This analysis explores a growing left-right imbalance in the electoral connection between citizens, parties, elections, and government. This imbalance is due, in part, to divergent left-right preferences for political engagement, organization, and communication. Support on the right for clearer social rules and simpler moral, racial and nationalist agendas are compatible with hierarchical, leader-centered party organizations that compete more effectively in elections. Parties on the left currently face greater challenges engaging citizens due to the popular meta-ideology of diversity and inclusiveness and demands for direct or deliberative democracy. What we term connective parties are developing technologies to perform core organizational functions, and some have achieved electoral success. However, when connective parties on the left try to develop shared authority processes, online and offline, they face significant challenges competing with more conventionally organized parties on the right

Zippin’ up my boots, goin’ back to my roots: Radical left parties in Southern Europe

Radical left parties actively encourage the participation of their members in internal decision-making and insist on promoting organised links to trade unions and social movements. As a party family, they deviate from what is considered to be the trend in which Western political parties have turned their backs on their social roots. Drawing on the experience of South European radical left parties from the fall of the Berlin Wall until the recent financial crisis, we argue that ideology, electoral incentives, party competition and external events explain the radical left's pronounced emphasis on linkage, while organisational trajectory explains variation within the party family in terms of the linkage strategies pursued

Explaining Institutional Change: Why Elected Politicians Implement Direct Democracy

In existing models of direct democratic institutions, the median voter benefits, but representative politicians are harmed since their policy choices can be overridden. This is a puzzle, since representative politicians were instrumental in creating these institutions. I build a model of direct democracy that explains why a representative might benefit from tying his or her own hands in this way. The key features are (1) that voters are uncertain about their representative's preferences; (2) that direct and representative elections are complementary ways for voters to control outcomes. The model shows that some politicians benefit from the introduction of direct democracy, since they are more likely to survive representative elections: direct democracy credibly prevents politicians from realising extreme outcomes. Historical evidence from the introduction of the initiative, referendum and recall in America broadly supports the theory, which also explains two empirical results that have puzzled scholars: legislators are trusted less, but reelected more, in US states with direct democracy. I conclude by discussing the potential for incomplete information and signaling models to improve our understanding of institutional change more generally

Judicial decision-making within political parties: A political approach

How do German intra-party tribunals manage internal conflicts? More specifically, why do they accept some cases for trial but reject others? Required by law to strictly adhere to implement rule of law standards, German intra-party tribunals are designed to insulate conflict regulation from politics. Meanwhile, research on judicial politics highlights the role of political and strategic considerations in accepting cases for trial. Building on the latter, we develop a theory that emphasizes tribunals’ political concerns such as winning elections. We test our hypotheses with a mixed-effects logit model on a novel data set covering 1088 tribunal decisions in six German parties from 1967 until 2015. Our findings indicate that political factors exert a strong effect on tribunal case acceptance. Tribunals are more likely to accept cases when suffering electoral loss and after losing government office. Moreover, tribunals dismiss cases more easily when their parties display relatively high levels of policy agreement

Honesty above all else? Expectations and perceptions of political conduct in three established democracies

The authors gratefully acknowledge financial support from the ESRC (grant number RES-000-22-3459) and British Academy (grant numbers SG-101785 and SG-52322). They would also like to thank two anonymous reviewers for their helpful comments and suggestions