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The possibility of using airglow techniques for estimating the electron density and height of the F layer is studied on the basis of a simple relationship between the height of the F2 peak and the column emission rates of the O I 6300 A and O I 1356 A lines. The feasibility of this approach is confirmed by a numerical calculation of F2 peak heights and electron densities from simultaneous measurements of O I 6300 A and O I 1356 A obtained with earth-facing photometers carried by the Ogo 4 satellite. Good agreement is established with the F2 peak heights estimates from top-side and bottom-side ionospheric sounding.

Encryption is a critical tool to protect sensitive information, prevent cybercrime and digital fraud, and authenticate digital transactions. However, the global encryption policy landscape is fracturing, with different countries pursuing different approaches to encryption through both legal and technical means. With authoritarianism on the rise around the world, encryption policy debates are about more than securing data. How different countries address the question of access to encryption will shape how global companies build their products, which will have significant implications for the tools and choices available to a wide range of users around the world. For vulnerable groups, both recoverable and unrecoverable encryption can be an essential means to protect communications and activities from repressive regimes, criminals, hate groups, and other bad actors. But malicious actors can also utilize encryption to hide their activities from law enforcement and security agencies. While average, everyday users have interests and needs in using encryption, the CSIS research team focused on a subset of user communities that, taken together, illuminate the trade-offs inherent in encryption policy choices. This study explores these issues through the lens of key encryption user groups (independent voices; at-risk groups; businesses and organizations; foreign policy; and terrorists, extremists, and hate groups), their governments, and U.S. values and interests. Its findings illuminate the central trade-offs policymakers face and demonstrate that decisions surrounding when, where, how, and by whom encryption is used should be more nuanced than an all-or-nothing approach.

Many countries are dependent upon capital flows for their balance of payments accounts. Sources of expenditures include foreign direct investment (FDI), portfolio investment (PI) and remittances. While the determinants of FDI and PI have been extensively analyzed, the analyses of remittance flows from host to home countries are largely lacking and wide-ranging. Factors predominantly not considered are domestic institutions which support or encourage international remittance exchange. Nations routinely desire to control international immigration and capital movement. Consequently they adopt domestic policies which create and enforce institutions that manage both capital and labor mobility across borders. Additionally, researchers commonly neglect to consider the impact of both the supply and demand factors simultaneously, or in other words, the domestic condition (home and host) which both push and pull migrants to migrate and remit. Further, given the non-dyadic nature of the data, there arises a need to "regionalize" the data. To test the effects of variations in immigration institutional attributes, I employ a pooled data set of approximately 104 nations from 1990 to 2004. Controlling for existing explanations and regional influences, I find that domestic institutions have a significant impact on the ability of an individual to migrate to a host country and to eventually remit back to their country of origin.