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We apply two methods to estimate the 21-cm bispectrum from data taken within the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA). Using data acquired with the Phase II compact array allows a direct bispectrum estimate to be undertaken on the multiple redundantly spaced triangles of antenna tiles, as well as an estimate based on data gridded to the uv-plane. The direct and gridded bispectrum estimators are applied to 21 h of high-band (167–197 MHz; z = 6.2–7.5) data from the 2016 and 2017 observing seasons. Analytic predictions for the bispectrum bias and variance for point-source foregrounds are derived. We compare the output of these approaches, the foreground contribution to the signal, and future prospects for measuring the bispectra with redundant and non-redundant arrays. We find that some triangle configurations yield bispectrum estimates that are consistent with the expected noise level after 10 h, while equilateral configurations are strongly foreground-dominated. Careful choice of triangle configurations may be made to reduce foreground bias that hinders power spectrum estimators, and the 21-cm bispectrum may be accessible in less time than the 21-cm power spectrum for some wave modes, with detections in hundreds of hours.
The Southern African Radiocarbon Database (SARD) is a new online, open-access database of published radiocarbon dates from southern African archaeological contexts. Compatible with the calibration, Bayesian modelling and mapping functionality of the OxCal software, the SARD will greatly assist in the documentation and analysis of chronological trends across the subcontinent. This article introduces the database and presents two case studies that demonstrate its utility and its integration with OxCal, comparing the temporal distribution of radiocarbon dates in two archaeologically well-investigated regions, and assessing the timing of Middle to Later Stone Age technological developments across the African subcontinent.
Ocular complaints prompt a significant number of emergency department (ED) visits, and they can range from benign to sight-threatening. Detailed fundoscopic examination is difficult, even for experienced providers. Point-of-care ultrasound (POCUS) is increasingly utilized in the ED for numerous applications, including ocular evaluation. We present a case in which ocular POCUS was used to diagnose a submacular hemorrhage in a patient who presented with acute painless loss of vision. Ocular POCUS can be readily employed to assess for myriad clinically significant pathologies.
The early village at Çatalhöyük (7100–6150 BC) provides important evidence for the Neolithic and Chalcolithic people of central Anatolia. This article reports on the use of lipid biomarker analysis to identify human coprolites from midden deposits, and microscopy to analyse these coprolites and soil samples from human burials. Whipworm (Trichuris trichiura) eggs are identified in two coprolites, but the pelvic soil samples are negative for parasites. Çatalhöyük is one of the earliest Eurasian sites to undergo palaeoparasitological analysis to date. The results inform how intestinal parasitic infection changed as humans modified their subsistence strategies from hunting and gathering to settled farming.
Women have organized around their gendered identity to accomplish political goals both inside and outside legislatures. Formal and informal institutional norms shape the form this collective action takes and whether it is successful. What, then, are the favorable conditions for organizing women's caucuses inside legislatures? Using an original dataset and employing an event history analysis, we identify the institutional conditions under which women's caucuses emerged in the 50 US states from 1972 to 2009. Within a feminist institutional framework, we argue that women's ability to alter existing organizational structures and potentially affect gender norms within legislatures is contextual. Although we find that women's presence in conjunction with Democratic Party control partially explains women's ability to act collectively and in a bipartisan way within legislatures, our analysis suggests that institutional-level variables are not enough to untangle this complicated phenomenon. Our work explains how gender and party interact to shape legislative behavior and clarifies the intractability of institutional norms while compelling further qualitative evidence to uncover the best conditions for women's collective action within legislatures.
The depressive-realism effect refers to a phenomenon in which depressed individuals are more realistic at assessing the relationship between two events than non-depressed individuals. Recent evidence suggests that the depressive realism hypothesis is weaker than first thought. Thus, we sought evidence for depressive-realism under conditions that we hypothesised would maximise the effect. We tested a clinically depressed sample of participants who were administered a rumination induction. Twenty-eight clinically depressed and 39 non-depressed participants were randomly allocated to either a rumination condition (focused on the causes, consequences, and meaning of their mood) or a distraction condition (focused on external objects/events such as a classroom). Participants then completed a contingency task in which there was no relationship between their responses and an outcome, and they were asked to make a judgment of how much control they had over an outcome. Both groups and conditions did not differ in their judgments of control; participants in all conditions showed a non-normative judgment of control. The depressive-realism effect was not observed in this study, even when depressed participants were encouraged to ruminate. Rather, the present study clearly demonstrates the robustness of the illusion of control.
As a frequent concern both of governments and of the public at large in Western Hemisphere nations, international migration is now more prominent than at any time since 1980. The episodic flow of seaborne refugees from Haiti since 1991 has been a key factor in spurring the inter-American community to oppose Haiti's military rulers. The flotilla of rafts leaving Cuba since early August 1994 has engendered high-profile negotiations on migration between Washington and Havana. The stream of undocumented labor migrants from Mexico to the United States has regained momentum since the late 1980s and is encountering increased public criticism, especially in the western United States.
Underlying these instances of political tension is a strong, and only partially-met, demand for migration to the United States from parts of Latin America and the Caribbean on the one hand, and a growing anxiety in the US to “control the nation's borders” on the other.
In this paper we undertake a quantitative analysis of the dynamic process by which ice underneath a dry porous debris layer melts. We show that the incorporation of debris-layer airflow into a theoretical model of glacial melting can capture the empirically observed features of the so-called Østrem curve (a plot of the melt rate as a function of debris depth). Specifically, we show that the turning point in the Østrem curve can be caused by two distinct mechanisms: the increase in the proportion of ice that is debris-covered and/or a reduction in the evaporative heat flux as the debris layer thickens. This second effect causes an increased melt rate because the reduction in (latent) energy used for evaporation increases the amount of energy available for melting. Our model provides an explicit prediction for the melt rate and the temperature distribution within the debris layer, and provides insight into the relative importance of the two effects responsible for the maximum in the Østrem curve. We use the data of Nicholson and Benn (2006) to show that our model is consistent with existing empirical measurements.
The 2007–9 financial crisis threatened economic disaster on a scale not seen since the Great Depression, but rapid state action prevented the widely feared devastation. The German response was considerably more generous to banks than the American or British bailouts. Drawing on interviews and primary sources in government, private firms, and media, Mitchell explains how the structure of national financial systems and interbank relationships produced extensive private rescues and pressure on different states. Mitchell explores the different responses and results in Germany, the UK and the US using a combination of detailed case study analyses of the three countries' responses to the crisis and a quantitative analysis of patterns of state responses to financial crises. This book will be essential reading for scholars and advanced students of political economy, comparative politics, economic sociology, economics, and public policy.