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We demonstrate that ordered microlens arrays with 10 m diam poly-dimethyl-siloxane lenses attached to glass substrates increase the light output of organic light emitting devices ͑OLED͒ by a factor of 1.5 over unlensed substrates. The lenses, which are considerably smaller than, and not aligned to the OLEDs, outcouple light that is emitted outside of the escape cone of the substrate. We show that an electrophosphorescent device based on a fac tris͑2-phenylpyridine͒Iridium ͑Ir͑ppy) 3 ͒ doped emitting layer has its external quantum efficiency increased from 9.5% using a flat glass substrate, to 14.5% at low current densities using a substrate with microlenses. No change in the emission spectrum is observed for different viewing angles using the lens arrays.

BackgroundWomen and students of color are widely underrepresented in most STEM fields. In order to investigate this underrepresentation, we interviewed 201 college seniors, primarily women and people of color, who either majored in STEM or started but dropped a STEM major. Here we discuss one section of the longer interview that focused on students’ sense of belonging, which has been found to be related to retention. In our analysis, we examine the intersections of race and gender with students’ sense of belonging, a topic largely absent from the current literature.ResultsWe found that white men were most likely to report a sense of belonging whereas women of color were the least likely. Further, we found that representation within one’s STEM sub-discipline, namely biology versus the physical sciences, impacts sense of belonging for women. Four key factors were found to contribute to sense of belonging for all students interviewed: interpersonal relationships, perceived competence, personal interest, and science identity.ConclusionsOur findings indicate that students who remain in STEM majors report a greater sense of belonging than those who leave STEM. Additionally, we found that students from underrepresented groups are less likely to feel they belong. These findings highlight structural and cultural features of universities, as well as STEM curricula and pedagogy, that continue to privilege white males.

Wealth ownership in the United States has long been concentrated in the hands of a small minority of the population, yet researchers have paid relatively little attention to the causes and consequences of this inequality. In this essay, we review the literature that does exist on wealth accumulation and distribution. We begin with an examination of the reasons that wealth inequality has received little empirical attention. We then discuss methods of creating empirical estimates of wealth accumulation and distribution, and we present some estimates of recent trends in wealth inequality. We explore a diverse collection of research that explains these trends, covering treatments of aggregate influences and individual and household factors. We conclude the chapter with a review of research on intergenerational processes and wealth mobility.

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