Using an Online Sample to Estimate the Size of an Offline Population.

Online data sources offer tremendous promise to demography and other social sciences, but researchers worry that the group of people who are represented in online data sets can be different from the general population. We show that by sampling and anonymously interviewing people who are online, researchers can learn about both people who are online and people who are offline. Our approach is based on the insight that people everywhere are connected through in-person social networks, such as kin, friendship, and contact networks. We illustrate how this insight can be used to derive an estimator for tracking the digital divide in access to the Internet, an increasingly important dimension of population inequality in the modern world. We conducted a large-scale empirical test of our approach, using an online sample to estimate Internet adoption in five countries (n ≈ 15,000). Our test embedded a randomized experiment whose results can help design future studies. Our approach could be adapted to many other settings, offering one way to overcome some of the major challenges facing demographers in the information age

The Mississippian fin de siècle in the middle Cumberland region of Tennessee

Bayesian chronological modeling is used to investigate the chronology for a large-scale human depopulation event during the Mississippian period (AD 1000–1600) known as the Vacant Quarter phenomenon. The Middle Cumberland region (MCR) of Tennessee is within the Vacant Quarter area, and six villages from the final phase of Mississippian activity in the MCR have been subjected to radiocarbon dating. Complete radiocarbon datasets from these sites are presented within an interpretative Bayesian statistical framework. The results provide a unique history of each settlement and demonstrate that Mississippian occupations at each site likely terminated in the mid- to late fifteenth and possibly early sixteenth centuries AD, which is 50 to 100 years later than the most recent estimate for the timing of the Vacant Quarter. Mississippian abandonment in the MCR was relatively quick, likely occurring over less than a century. The exact reasons for abandonment are not entirely clear but appear to be linked to climate change. A radiocarbon simulation experiment indicates that future robust radiocarbon dating with well-selected samples could greatly improve the chronological precision for this late Mississippian activity. More broadly, this example demonstrates that model building with radiocarbon simulations can be used to address regional-scale chronological issues within the American Southeast and beyond

3D printing and high tibial osteotomy

High tibial osteotomy (HTO) is a relatively conservative surgical option in the management of medial knee pain. Thus far, the outcomes have been variable, and apparently worse than the arthroplasty alternatives when judged using conventional metrics, owing in large part to uncer - tainty around the extent of the correction planned and achieved. This review paper introduces the concept of detailed 3D planning of the procedure, and describes the 3D printing technology that enables the plan to be performed. The different ways that the osteotomy can be undertaken, and the varying guide designs that enable accurate regis - tration are discussed and described. The system accuracy is reported. In keeping with other assistive technologies, 3D printing enables the surgeon to achieve a preoperative plan with a degree of accuracy that is not possible using conventional instruments. With the advent of low dose CT, it has been possible to confirm that the procedure has been under - taken accurately too. HTO is the ‘ultimate’ personal intervention: the amount of correction needed for optimal offloading is not yet com - pletely understood. For the athletic person with early medial joint line over - load who still runs and enjoys life, HTO using 3D printing is an attractive option. The clinical effectiveness remains unproven

Aerospike thrust chamber program

An existing, but damaged, 25,000-pound thrust, flightweight, oxygen/hydrogen aerospike rocket thrust chamber was disassembled and partially repaired. A description is presented of the aerospike chamber configuration and of the damage it had suffered. Techniques for aerospike thrust chamber repair were developed, and are described, covering repair procedures for lightweight tubular nozzles, titanium thrust structures, and copper channel combustors. Effort was terminated prior to completion of the repairs and conduct of a planned hot fire test program when it was found that the copper alloy walls of many of the thrust chamber's 24 combustors had been degraded in strength and ductility during the initial fabrication of the thrust chamber. The degradation is discussed and traced to a reaction between oxygen and/or oxides diffused into the copper alloy during fabrication processes and the hydrogen utilized as a brazing furnace atmosphere during the initial assembly operation on many of the combustors. The effects of the H2/O2 reaction within the copper alloy are described

Occurrence of Parasitoid Wasps, Baeus sp. and Gelis sp., in the Egg Sacs of the Wolf Spiders Pardosa moesta and Pardosa sternalis (Araneae, Lycosidae) in Southeastern Idaho

Egg sacs of the wolf spiders Pardosa moesta and Pardosa sternalis were sampled for two years during June to September in southeastern Idaho. Parasitoid wasps, Baeus sp. (Sceleonidae) and Gelis sp. (Ichneumonidae), were observed in the egg sacs of both Pardosa species. Of 322 egg sacs examined, 14.6% were parasitized. Parasitism of egg sacs occurred throughout most of the Pardosa egg sac-carrying season

A Project Based Approach to Statistics and Data Science

In an increasingly data-driven world, facility with statistics is more important than ever for our students. At institutions without a statistician, it often falls to the mathematics faculty to teach statistics courses. This paper presents a model that a mathematician asked to teach statistics can follow. This model entails connecting with faculty from numerous departments on campus to develop a list of topics, building a repository of real-world datasets from these faculty, and creating projects where students interface with these datasets to write lab reports aimed at consumers of statistics in other disciplines. The end result is students who are well prepared for interdisciplinary research, who are accustomed to coping with the idiosyncrasies of real data, and who have sharpened their technical writing and speaking skills

The feasibility of a programmed heat shield for solar cell performance control

Feasibility of programmed heat shield for temperature and power control for spacecraft on-board powe

Community, poverty, power: The politics of tribal self-determination, 1960--1968.

"Community, Poverty, Power" underscores the need for scholars to transcend conventional definitions of Indian history, combine micro and macro scales of analysis, and blend social and political perspectives. In addition to expanding the interpretive ground upon which the War on Poverty is assessed and suggesting a different way of thinking about the emergence of tribal self-determination, it provides a context for understanding the heightened militancy of the Red Power movement. It also re-envisions the meaning of activism so that it includes people who worked within the system in order to affect change. To the extent that the idea of tribal self-determination entered national discourse between 1960 and 1968, it did so because of these continuing encounters between natives and newcomers."Community, Poverty, Power" explores how tribal self-determination moved from the periphery to the center of the public sphere during the 1960s. Focusing on the Association on American Indian Affairs, National Congress of American Indians, American Indian Chicago Conference, Workshop on American Indian Affairs, and National Indian Youth Council, Part One demonstrates that the struggle against termination and assimilation cannot be understood apart from the global politics of decolonization and domestic contests over race and mass society. Having situated the study in this milieu, Part Two examines the central role the War on Poverty, and particularly the Community Action Program, played in the politics of self-determination after its inauguration in 1964.Based on original manuscript research and interviews with Vine Deloria Jr., Forrest Gerard, Dr. Jim Wilson, and other central actors, these chapters detail the complex series of negotiations regarding the nature of poverty, the meaning of community, and the fate of tribal identities that followed. Two additional chapters focused on Oklahoma, and informed by interviews with LaDonna Harris, Senator Fred R. Harris, Iola Hayden, and others demonstrate the interconnectedness of local people's experiences and the decisions made by national policymakers. The dissertation concludes with a Coda that carries the study forward to the spring of 1968 and the Poor People's Campaign---a pivotal moment that evidenced the limitations of social reform and the impending fragmentation of the Indian rights movement