An Exorbitant Privilege in the First Age of International Financial Integration

The exorbitant privilege literature analyzes the positive differential returns on net foreign assets enjoyed by the United States in the last quarter of the twentieth century as the issuer of the global reserve currency. In the first age of international financial integration (1870-1914), the global reserve currency of the period was the British pound sterling. Whether the United Kingdom enjoyed a similar privilege is analyzed with a new dataset, encompassing microdata on railroad and government financial securities. The use of microdata avoids the flaws that have plagued the US studies, particularly the use of incompatible aggregate variables. New measures of Britain’s net external position provide estimates on capital gains and dividend yields. As the issuer of the global reserve currency, Britain received average revenues of 13.4% of GDP from its international investment position. The country satisfied the necessary condition for the existence of an exorbitant privilege. Nonetheless, Britain’s case is slightly different from the American one. British external assets received higher returns than were paid on external liabilities for each class, but British invested mostly in securities with low profile of risk. The low return on its net external position meant that, for most of the time, Britain would not receive positive revenues from the rest of the world if it were a net debtor country, but this pattern changed after 1900. The finding supports the claim that, at least partially, exorbitant privilege is a general characteristic of the issuer of the global reserve currency and not unique to the late twentieth century US.

Integration of virus-like particle macromolecular bioreceptors in electrochemical biosensors

Rapid, sensitive and selective detection of chemical hazards and biological pathogens has shown growing importance in the fields of homeland security, public safety and personal health. In the past two decades, efforts have been focusing on performing point-of-care chemical and biological detections using miniaturized biosensors. These sensors convert target molecule binding events into measurable electrical signals for quantifying target molecule concentration. However, the low receptor density and the use of complex surface chemistry in receptors immobilization on transducers are common bottlenecks in the current biosensor development, adding to the cost, complexity and time. This dissertation presents the development of selective macromolecular Tobacco mosaic virus-like particle (TMV VLP) biosensing receptor, and the microsystem integration of VLPs in microfabricated electrochemical biosensors for rapid and performance-enhanced chemical and biological sensing. Two constructs of VLPs carrying different receptor peptides targeting at 2,4,6-trinitrotoluene (TNT) explosive or anti-FLAG antibody are successfully bioengineered. The VLP-based TNT electrochemical sensor utilizes unique diffusion modulation method enabled by biological binding between target TNT and receptor VLP. The method avoids the influence from any interfering species and environmental background signals, making it extremely suitable for directly quantifying the TNT level in a sample. It is also a rapid method that does not need any sensor surface functionalization process. For antibody sensing, the VLPs carrying both antibody binding peptides and cysteine residues are assembled onto the gold electrodes of an impedance microsensor. With two-phase immunoassays, the VLP-based impedance sensor is able to quantify antibody concentrations down to 9.1 ng/mL. A capillary microfluidics and impedance sensor integrated microsystem is developed to further accelerate the process of VLP assembly on sensors and improve the sensitivity. Open channel capillary micropumps and stop-valves facilitate localized and evaporation-assisted VLP assembly on sensor electrodes within 6 minutes. The VLP-functionalized impedance sensor is capable of label-free sensing of antibodies with the detection limit of 8.8 ng/mL within 5 minutes after sensor functionalization, demonstrating great potential of VLP-based sensors for rapid and on-demand chemical and biological sensing.