Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This thesis represents a significant advance in our understanding of the synthesis and propertiesof two-dimensional (2D) materials. The author’s work breaks new ground in the understanding of a number of 2D crystals, including atomically thin transition metal dichalcogenides, graphene, and their heterostructures, that are technologically important to next-generation electronics. In addition to critical new results on the direct growth of 2D heterostructures, it also details growth mechanisms, surface science, and device applications of “epi-grade” 2D semiconductors, which are essential to low-power electronics, as well as for extending Moore’s law. Most importantly, it provides an effective alternative to mechanically exfoliate 2D layers for practical applications. .

Heterostructures. --- Crystals --- Superlattices as materials --- Nanotechnology. --- Optical materials. --- Surfaces (Physics). --- Crystallography. --- Semiconductors. --- Optical and Electronic Materials. --- Surfaces and Interfaces, Thin Films. --- Crystallography and Scattering Methods. --- Molecular technology --- Nanoscale technology --- High technology --- Optics --- Materials --- Leptology --- Physical sciences --- Mineralogy --- Physics --- Surface chemistry --- Surfaces (Technology) --- Electronic materials. --- Materials—Surfaces. --- Thin films. --- Films, Thin --- Solid film --- Solid state electronics --- Solids --- Coatings --- Thick films --- Electronic materials --- Crystalline semiconductors --- Semi-conductors --- Semiconducting materials --- Semiconductor devices --- Electrical engineering --- Electronics

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

In recent years, there has been widespread concern that misinformation on social media is damaging societies and democratic institutions. In response, social media platforms have announced actions to limit the spread of false content. We measure trends in the diffusion of content from 569 fake news websites and 9,540 fake news stories on Facebook and Twitter between January 2015 and July 2018. User interactions with false content rose steadily on both Facebook and Twitter through the end of 2016. Since then, however, interactions with false content have fallen sharply on Facebook while continuing to rise on Twitter, with the ratio of Facebook engagements to Twitter shares decreasing by 60 percent. In comparison, interactions with other news, business, or culture sites have followed similar trends on both platforms. Our results suggest that the relative magnitude of the misinformation problem on Facebook has declined since its peak.

Zonder onderwerpscode: economie

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

In recent years, there has been widespread concern that misinformation on social media is damaging societies and democratic institutions. In response, social media platforms have announced actions to limit the spread of false content. We measure trends in the diffusion of content from 569 fake news websites and 9,540 fake news stories on Facebook and Twitter between January 2015 and July 2018. User interactions with false content rose steadily on both Facebook and Twitter through the end of 2016. Since then, however, interactions with false content have fallen sharply on Facebook while continuing to rise on Twitter, with the ratio of Facebook engagements to Twitter shares decreasing by 60 percent. In comparison, interactions with other news, business, or culture sites have followed similar trends on both platforms. Our results suggest that the relative magnitude of the misinformation problem on Facebook has declined since its peak.

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Concerned about the low academic ability of public school teachers, in the 1990s and 2000s, some states increased licensing stringency to weed out low-quality candidates, while others decreased restrictions to attract high-quality candidates. We offer a theoretical model justifying both reactions. Using data from 1991-2007 on licensing requirements and teacher quality--as measured by the selectivity of teachers' undergraduate institutions--we find that stricter licensing requirements, especially those emphasizing academic coursework, increase the left tail of the quality distribution for secondary school teachers without significantly decreasing quality for high-minority or high-poverty districts.

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)