Constraining Radon Backgrounds in LZ

The LZ dark matter detector, like many other rare-event searches, will suffer from backgrounds due to the radioactive decay of radon daughters. In order to achieve its science goals, the concentration of radon within the xenon should not exceed $2\mu$Bq/kg, or 20 mBq total within its 10 tonnes. The LZ collaboration is in the midst of a program to screen all significant components in contact with the xenon. The four institutions involved in this effort have begun sharing two cross-calibration sources to ensure consistent measurement results across multiple distinct devices. We present here five preliminary screening results, some mitigation strategies that will reduce the amount of radon produced by the most problematic components, and a summary of the current estimate of radon emanation throughout the detector. This best estimate totals $<17.3$ mBq, sufficiently low to meet the detector's science goals.Comment: Low Radioactivity Techniques (LRT) 2017 Workshop Proceedings. 6 pages; 3 figure

Student Outcomes from the Collective Design and Delivery of Culturally Relevant Engineering Outreach Curricula in Rural and Appalachian Middle Schools

Middle school is a pivotal time for career choice, and research is rich with studies on how students perceive engineering, as well as corresponding intervention strategies to introduce younger students to engineering and inform their conceptions of engineering. Unfortunately, such interventions are typically not designed in culturally relevant ways. Consequently, there continues to be a lack of students entering engineering and a low level of diverse candidates for this profession. The purpose of this study was to explore how students in rural and Appalachian Virginia conceive of engineering before and after engagement with culturally relevant hands-on activities in the classroom. We used student responses to the Draw an Engineer Test (DAET), consisting of a drawing and several open-ended prompts administered before and after the set of engagements, to answer our research questions related to changes in students’ conceptions of engineering. We used this study to develop recommendations for teachers for the use of such engineering engagement practices and how to best assess their outcomes, including looking at the practicality of the DAET. Overall, we found evidence that our classroom engagements positively influenced students’ conceptions of engineering in these settings

From ‘Young Women’ to ‘Female Adolescents’:Dutch Advice Literature during the Long Nineteenth Century

In late eighteenth-century Europe, there was a rapid expansion in the publication of advice books directed at young adult women. Based on an examination of conduct books published in the Netherlands, this chapter traces the changing format of the genre from the last quarter of the eighteenth century through to the early decades of the twentieth century. It explores how women pedagogues in the nineteenth century developed new ways of advising young women that gave readers greater control over their life choices. In the early twentieth century, the emerging social sciences drew attention to the physical and emotional changes involved in female adolescence, prescribing for the young woman strict forms of behaviour

A geoneutrino experiment at Homestake

A significant fraction of the 44TW of heat dissipation from the Earth's interior is believed to originate from the decays of terrestrial uranium and thorium. The only estimates of this radiogenic heat, which is the driving force for mantle convection, come from Earth models based on meteorites, and have large systematic errors. The detection of electron antineutrinos produced by these uranium and thorium decays would allow a more direct measure of the total uranium and thorium content, and hence radiogenic heat production in the Earth. We discuss the prospect of building an electron antineutrino detector approximately 700m^3 in size in the Homestake mine at the 4850' level. This would allow us to make a measurement of the total uranium and thorium content with a statistical error less than the systematic error from our current knowledge of neutrino oscillation parameters. It would also allow us to test the hypothesis of a naturally occurring nuclear reactor at the center of the Earth.Comment: proceedings for Neutrino Sciences 2005, submitted to Earth, Moon, and Planet

An Illustration of Inverse Probability Weighting to Estimate Policy-Relevant Causal Effects

Traditional epidemiologic approaches allow us to compare counterfactual outcomes under 2 exposure distributions, usually 100% exposed and 100% unexposed. However, to estimate the population health effect of a proposed intervention, one may wish to compare factual outcomes under the observed exposure distribution to counterfactual outcomes under the exposure distribution produced by an intervention. Here, we used inverse probability weights to compare the 5-year mortality risk under observed antiretroviral therapy treatment plans to the 5-year mortality risk that would had been observed under an intervention in which all patients initiated therapy immediately upon entry into care among patients positive for human immunodeficiency virus in the US Centers for AIDS Research Network of Integrated Clinical Systems multisite cohort study between 1998 and 2013. Therapy-naïve patients (n = 14,700) were followed from entry into care until death, loss to follow-up, or censoring at 5 years or on December 31, 2013. The 5-year cumulative incidence of mortality was 11.65% under observed treatment plans and 10.10% under the intervention, yielding a risk difference of −1.57% (95% confidence interval: −3.08, −0.06). Comparing outcomes under the intervention with outcomes under observed treatment plans provides meaningful information about the potential consequences of new US guidelines to treat all patients with human immunodeficiency virus regardless of CD4 cell count under actual clinical conditions

A longitudinal, HIV care continuum: 10-year restricted mean time in each care continuum stage after enrollment in care, by history of IDU

We present a novel, patient-centric, longitudinal summary of patient progress through the HIV care continuum. Using this new approach, we compare person-time spent alive, in care, on antiretroviral therapy (ART) and virally suppressed among persons who inject drugs (PWID) and those who do not (non-IDU)