Undermining and Strengthening Social Networks through Network Modification

Social networks have well documented effects at the individual and aggregate level. Consequently it is often useful to understand how an attempt to influence a network will change its structure and consequently achieve other goals. We develop a framework for network modification that allows for arbitrary objective functions, types of modification (e.g. edge weight addition, edge weight removal, node removal, and covariate value change), and recovery mechanisms (i.e. how a network responds to interventions). The framework outlined in this paper helps both to situate the existing work on network interventions but also opens up many new possibilities for intervening in networks. In particular use two case studies to highlight the potential impact of empirically calibrating the objective function and network recovery mechanisms as well as showing how interventions beyond node removal can be optimised. First, we simulate an optimal removal of nodes from the Noordin terrorist network in order to reduce the expected number of attacks (based on empirically predicting the terrorist collaboration network from multiple types of network ties). Second, we simulate optimally strengthening ties within entrepreneurial ecosystems in six developing countries. In both cases we estimate ERGM models to simulate how a network will endogenously evolve after intervention

Missing Nonvoters and Misweighted Samples:Explaining the 2015 Great British Polling Miss

Preelection polls for the 2015 UK General Election missed the final result by a considerable margin: underestimating the Conservative Party and overestimating Labour. Analyzing evidence for five theories of why the polls missed using British Election Study (BES) data, we find limited evidence for systematic vote intention misreporting, late swing, systematically different preferences among “don’t knows,” or differential turnout of parties’ supporters. By comparing the BES face-to-face probability sample and BES Internet panel, we show that the online survey’s polling error is primarily caused by undersampling nonvoters, then weighting respondents to represent the general population. Consequently, demographic groups with a low probability of voting are overweighted within the voter subsample. Finally, we show that this mechanism is likely partially responsible for the polls overestimating the Liberal Democrats in 2010, illustrating that this is a long-standing problem

Surprise, surprise! (again): the 2017 British general election exit poll

While most pollsters and pundits expected the Conservatives to win an increased majority in Britain's June election, the election day exit poll forecast something different. John Curtice, Stephen Fisher, Jouni Kuha and Jonathan Mellon explain how the poll works, and why it made the right call

Did young voters turn out in droves for Corbyn? The myth of the 2017 youthquake election

That hordes of previously disengaged young voters turned out to support Jeremy Corbyn in the 2017 election has become something of an assumed fact. But the assumption has been largely based on anecdotes. Chris Prosser, Ed Fieldhouse, Jane Green, Jonathan Mellon, and Geoff Evans use the British Election Study face-to-face survey to examine the claim

Application of a robotics path planning algorithm to assess the risk of mobile bearing dislocation in lateral unicompartmental knee replacement

Due to ligament laxity, bearing dislocation occurs in 1–6% of Oxford Domed Lateral (ODL) replacements with most dislocations occurring medially. Dislocations were studied using a previously built mechanical rig, however testing using the rig was inefficient. The aim of this study was to develop a better tool that was more reliable and efficient. An established robotics software package, the Open Motion Planning Library, was modified to accept the ODL components. Using a robotics path planning algorithm, the mobile bearing was allowed to find a way out from between the femoral and tibial components i.e. to dislocate. Testing assessed a range of clinically relevant positions of the femoral component relative to the tibial component. Dislocations were labelled as medial, lateral, anterior or posterior depending on the dislocation direction. The Distraction to Dislocation (DD) measured the minimum vertical distraction of the femoral component from the tibial component for a dislocation to occur. Results were validated against the mechanical rig. Statistical analysis of medial dislocation showed excellent agreement with an intraclass correlation value of 0.993 (95% CI 0.982–0.998). All DDs from the dislocation analysis tool were within 1 mm of the mechanical rig DDs with results sharing a remarkably similar trend. The robotics dislocation analysis tool output DDs which were marginally higher than the manual mechanical rig: 0.50 mm anteriorly, 0.25 mm posteriorly and 0.50 mm laterally. Medially, the computational DD differed on average by 0.09 mm (stand deviation: 0.2026 mm). Our study describes the development and validation of a novel robotics dislocation analysis tool, which allows mobile bearing dislocation risk quantification. The tool may also be used to improve surgical implantation parameters and to assess new implant designs that aim to reduce the medial dislocation risk to an acceptable level

Characterization of the Structure of Cation-DopedBacteriogenic Uranium Oxides using X-Ray Diffraction

Remediation of uranium contamination in subsurface groundwater has become imperative as previous research and manufacturing involving radionuclides has led to contamination of groundwater sources. A possible in situ solution for sequestration of uranium is a bacterial process in which Shewanella oneidensis MR-1 reduces the soluble (and thus mobile) U(VI) oxidation state into the less mobile UO{sub 2} crystalline phase. However, the long term stability of the UO2 compound must be studied as oxidative conditions could return it back into the U(VI) state. Incorporation of other cations into the structure during manufacture of the UO{sub 2} could alter the dissolution behavior. A wide angle x-ray scattering (WAXS) experiment was performed to determine whether or not calcium, manganese, and magnesium are incorporated into this structure. If so, the substituted atoms would cause a contraction or expansion in the lattice because of their differing size, causing the lattice constant to be altered. After several stages of data reduction, the WAXS diffraction peaks were fit using the Le Bail fit method in order to determine the lattice constant. Initial results suggest that there may be incorporation of manganese into the UO{sub 2} structure due to a .03 Angstrom decrease in lattice constant, but more data is needed to confirm this. The calcium and magnesium doped samples showed little to no change in the lattice constant, indicating no significant incorporation into the structure. Most importantly, this experiment revealed an artifact of the cleaning process used to remove the bacteria from the sample. It appears the NaOH used to clean the samples is contracting the lattice also by {approx} .03 Angstroms, but no physical explanation is offered as of yet

Electoral Shocks

This book offers a novel perspective on British elections, focusing on the importance of increasing electoral volatility in British elections, and the role of electoral shocks in the context of increasing volatility. It demonstrates how shocks have contributed to the level of electoral volatility, and also which parties have benefited from the ensuing volatility. It follows in the tradition of British Election Study books, providing a comprehensive account of specific election outcomes—the General Elections of 2015 and 2017—and a more general approach to understanding electoral change.We examine five electoral shocks that affected the elections of 2015 and 2017: the rise in EU immigration after 2004, particularly from Eastern Europe; the Global Financial Crisis prior to 2010; the coalition government of the Conservatives and the Liberal Democrats between 2010 and 2015; the Scottish Independence Referendum in 2014; and the European Union Referendum in 2016.Our focus on electoral shocks offers an overarching explanation for the volatility in British elections, alongside the long-term trends that have led us to this point. It offers a way to understand the rise and fall of the UK Independence Party (UKIP), Labour’s disappointing 2015 performance and its later unexpected gains, the collapse in support for the Liberal Democrats, the dramatic gains of the Scottish National Party (SNP) in 2015, and the continuing period of tumultuous politics that has followed the EU Referendum and the General Election of 2017. It provides a new way of understanding electoral choice in Britain, and beyond, and a better understanding of the outcomes of recent elections