an anonymous referee, and to participants to the seminar at the European Central Bank Fiscal Policy Division for useful discussions and suggestions. The views expressed herein are those of the author(s) and not necessarily those of the National Bureau of Economic Research.

No abstract

We use a panel of 16 OECD countries over several decades to investigate the e!ects of government debts and decits on long-term interest rates. In simple static specications, a one-percentage-point increase in the primary decit relative to GDP increases contempora-neous long-term interest rates by about 10 basis points. In a vector autoregression (VAR), the same shock leads to a cumulative increase of almost 150 basis points after 10 years. The e!ect of debt on interest rates is non-linear: only for countries with above-average levels of debt does an increase in debt a!ect the interest rate. World scal policy is also important: an increase in total OECD-government borrowing increases each country's interest rates. However , domestic scal policy continues to a!ect domestic interest rates even after controlling for worldwide debts and decits.

No abstract

We report the synthesis of composite RuO(2)/poly(3,4-ethylenedioxythiophene) (PEDOT) nanotubes with high specific capacitance and fast charging/discharging capability as well as their potential application as electrode materials for a high-energy and high-power supercapacitor. RuO(2)/PEDOT nanotubes were synthesized in a porous alumina membrane by a step-wise electrochemical deposition method, and their structures were characterized using electron microscopy. Cyclic voltammetry was used to qualitatively characterize the capacitive properties of the composite RuO(2)/PEDOT nanotubes. Their specific capacitance, energy density and power density were evaluated by galvanostatic charge/discharge cycles at various current densities. The pseudocapacitance behavior of these composite nanotubes originates from ion diffusion during the simultaneous and parallel redox processes of RuO(2) and PEDOT. We show that the energy density (specific capacitance) of PEDOT nanotubes can be remarkably enhanced by electrodepositing RuO(2) into their porous walls and onto their rough internal surfaces. The flexible PEDOT prevents the RuO(2) from breaking and detaching from the current collector while the rigid RuO(2) keeps the PEDOT nanotubes from collapsing and aggregating. The composite RuO(2)/PEDOT nanotube can reach a high power density of 20 kW kg(-1) while maintaining 80% energy density (28 Wh kg(-1)) of its maximum value. This high power capability is attributed to the fast charge/discharge of nanotubular structures: hollow nanotubes allow counter-ions to readily penetrate into the composite material and access their internal surfaces, while a thin wall provides a short diffusion distance to facilitate ion transport. The high energy density originates from the RuO(2), which can store high electrical/electrochemical energy intrinsically. The high specific capacitance (1217 F g(-1)) which is contributed by the RuO(2) in the composite RuO(2)/PEDOT nanotube is realized because of the high specific surface area of the nanotubular structures. Such PEDOT/RuO(2) composite nanotube materials are an ideal candidate for the development of high-energy and high-power supercapacitors.