The XENON1T Spin-Independent WIMP Dark Matter Search Results and a Model to Characterize the Reduction of Electronegative Impurities in Its 3.2 Tonne Liquid Xenon Detector

Over much of the last century evidence has been building for a new component of our universe that interacts primarily through gravitation. Known as cold dark matter, this non-luminous source is predicted to constitute 83% of matter and 26% of mass-energy in the universe. Experiments are currently searching for dark matter via its possible creation in particle colliders, annihilation in high-density regions of the universe, and interactions with Standard Model particles. So far dark matter has eluded detection so its composition and properties remain a mystery. Weakly interacting massive particles (WIMPs) are hypothetical elementary particles that interact on the scale of the weak nuclear force. They naturally satisfy predictions from extensions of the Standard Model, and are one of the most favored dark matter candidates. A number of direct detection experiments dedicated to measuring their predicted interactions with atomic nuclei have been constructed over the last 25 years. Liquid xenon dual phase time projection chambers (TPCs) have led the field for spin-independent WIMP searches at WIMP masses of >10 GeV/c^2 for most of the last decade. XENON1T is the first tonne-scale TPC, and with 278.8 days of dark matter data has set the strictest limits on WIMP-nucleon interaction cross sections above WIMP masses of 6 GeV/c^2, with a minimum of 4.1 x10^{-47} cm^2 at 30 GeV/c^2. XENON1T and the analysis that led to this result are discussed, with an emphasis on electronic and nuclear recoil calibration fits, which help discriminate between background and WIMP-like events. Interactions in liquid xenon produce light and charge that are measured in TPCs. These signals are attenuated by electronegative impurities including O_2 and H_2O, which are homogeneously distributed throughout the liquid xenon. The decrease in observables enlarges the uncertainty in our analysis, and can decrease our sensitivity. Methods on measuring the charge loss are presented, and a physics model that describes the behavior of the electronegative impurity concentration over the lifetime of XENON1T is derived. The model is shown to successfully explain the more than two years of data

Increasing Accuracy in Police Report Writing

The current alternative thesis project consisted of creating an online learning course intended to increase the accuracy with which preservice and in-service police officers write police incident reports. The online course consists of 6 separate modules and utilizes principles of applied behavior analysis (ABA) to assist the learner in understanding and applying the content of the modules. Specifically, components of interactive computer training (ICT), consisting of video modeling, voice over narration, interactive activities, and self-pace module design were implemented in the design of the learning course. Opportunities throughout the course allow the learner to self-reflect, self-assess, and receive feedback

UK voters see divided political parties as less able to makesensible or coherent policies

It is often said that ‘divided parties lose elections’, with the experience of the Conservatives in the 1990s cited as supporting evidence. But is this the case? Looking at evidence from the British Election Survey (BES), Zachary D. Greene argues that perceptions of party disunity does indeed play a role in how voters assess the competence of parties

Setting the policy agenda: the role of economic context, parliamentary majority and party membership

There are conflicting beliefs about the influence of parties on policy. Sceptical observers point to broken pledges and competing demands on governments’ legislative time; others decry overt partisanship. Yet, as Shaun Bevan and Zachary Greene argue, parties do draw policies towards their stated goals if they cannot complete their policy mandates

Ruling divided : disagreement, issue salience and portfolio allocation

Issue salience and ideological disagreement often predict coalition government behavior. However, research on portfolio allocation has yet to fully specify the complex relationship between issue salience, disagreement and coalition negotiations. Scholars treat issue salience and disagreement as distinct and disconnected, despite evidence that they work together and with conditional effects in a range of settings. Following a logic of portfolio trades or ‘logrolls’, we propose that the relative salience of issues and disagreements at the issue level within the coalition both moderate the effect of issue salience on portfolio allocation. Using data drawn from the Parliamentary Democracy Data Archive, we find compelling evidence for our theory that links party manifestos to portfolio allocation. Consistent with a story on the conditional effect of salience and disagreement, we find evidence that the effect of salience is mitigated by the extent of disagreement between coalition parties

Leadership competition and disagreement at party national congresses

Theories often explain intraparty competition based on electoral conditions and intraparty rules. This article further opens this black box by considering intraparty statements of preferences. In particular, it predicts that intraparty preference heterogeneity increases after electoral losses, but that candidates deviating from the party's median receive fewer intraparty votes. Party members grant candidates greater leeway to accommodate competing policy demands when in government. The study tests the hypotheses using a new database of party congress speeches from Germany and France, and uses automated text classification to estimate speakers' relative preferences. The results demonstrate that speeches at party meetings provide valuable insights into actors' preferences and intraparty politics. The article finds evidence of a complex relationship between the governing context, the economy and intraparty disagreement

Maintaining partisan ties : preference divergence and partisan collaboration in Western Europe

Parties coordinate on a range of activities. They invite leaders from other parties to their national meetings, run joint electoral platforms and even form parliamentary factions and coalition governments. The implications of regular cooperation such as the case of pre-electoral coalitions (PECs) for party positioning are unexplored. Parties form PECs to reduce competition for voters with ideologically close competitors and to signal their ability to cohesively govern. Building on this logic, we argue that parties’ preferences converge in PECs to demonstrate their ability to govern together and diverge when parties observe that this tactic has failed to attract voter support in past elections. We demonstrate support for our approach using data on electoral coalition participation, party positions and parties’ internal speeches. Additional evidence from an extreme case of an enduring electoral coalition in Germany shows that PECs have dramatic effects on parties’ positions

How electoral competition explains preference convergence and divergence in pre-electoral coalitions

While most coalition governments form after the results of an election, some parties choose to announce their intention to form pre-electoral coalitions before a vote has been held. Based on a recent study, Zachary Greene and Matthias Haber explore why parties, which are usually in direct conflict with one another for electoral support, choose to engage in this kind of cooperation. Their findings highlight that close competitors can often use their electoral context to mutual advantage and that parties do not always benefit from strictly adversarial approaches

Polarisation, accountability, and interstate conflict

Voters constrain democratic leaders’ foreign policy decisions. Yet, studies show that elite polarisation restricts the choices available to voters, limiting their ability to punish or reward incumbent governments. Building on a comparative elections and accountability perspective, we hypothesise that the governing context moderates the effectiveness of domestic punishment and reward. The rise of elite polarisation in many democracies undermines voters’ ability to sanction leaders through elections. Linking data on international crises to domestic polarisation, we find that leaders are more likely to be involved in the initiation of inter-state disputes, resulting disputes will be more likely to result in prolonged conflict, and ultimately that foreign policy outcomes exhibit greater variance. Results from our analysis and extensive robustness checks demonstrate evidence that increased dispersion of preferences among key actors can lead to extreme and negative foreign policy outcomes as electoral mechanisms fail to reign in and hold governing parties to account

Should we measure professionalism with an index? A note on theory and practice in state legislative professionalism research

Legislative professionalism has played a prominent role in state politics research for decades. Despite the attention paid to its causes and consequences, recent research has largely set aside questions about professionalism’s conceptualization and operationalization. Usually measuring it as an aggregate index, scholars theoretically and empirically treat professionalism as a unidimensional concept. In this article, we argue that exclusive use of aggregate indices can limit state politics research. Using a new dataset with almost 40 years of data on state legislative resources, salary, and session length, we reconsider the validity of using an index to study professionalism across the states. We evaluate the internal consistency of professionalism components over time, the relationship between components and the Squire Index, and the degree to which professionalism components are unidimensional using classical multidimensional scaling. We find enough commonality and enough variation between professionalism components to support a range of measurement strategies like the use of unidimensional indices (such as the Squire Index), disaggregating the components and analyzing their effects individually, or formulating multidimensional measures. Scholars should take care to choose the appropriate measure of the concept that best fits the causal relationships under examination