Single-wall fullerene nanotubes were converted from nearly endless, highly tangled ropes into short, open-ended pipes that behave as individual macromolecules. Raw nanotube material was purified in large batches, and the ropes were cut into 100- to 300-nanometer lengths. The resulting pieces formed a stable colloidal suspension in water with the help of surfactants. These suspensions permit a variety of manipulations, such as sorting by length, derivatization, and tethering to gold surfaces.
We study the Markov Perfect Equilibrium in a dynamic game where agents have non-constant time preference, decentralized households determine aggregate savings, and a planner chooses climate policy. The paper is the first to solve this problem with general discounting and general functional forms. With time-inconsistent preferences, a commitment device that allows a planner to choose climate policy for multiple periods is potentially very valuable. Nevertheless, our quantitative results show that while a permanent commitment device would be very valuable, the ability to commit policy for “only” 100 years adds less than two percent to the value of climate policy without commitment. We solve a log-linear version of the model analytically, generating a formula for the optimal carbon tax that includes the formula in Golosov et al. (2014) as a special case. More importantly, we develop new algorithms to solve the general game numerically. Convex damages lead to strategic interactions across generations of planners that lower the optimal carbon tax by forty-five percent relative to the scenario without strategic interactions.
Using Colorado as a case study, we develop a state-level computable general equilibrium (CGE) model that reflects the roles of coal, natural gas, wind, solar, and hydroelectricity in supplying electricity. We focus on the economic impact of implementing Colorado's existing Renewable Portfolio Standard, updated in 2013. This requires that 25% of state generation come from qualifying renewable sources by 2020. We evaluate the policy under a variety of assumptions regarding wind integration costs and assumptions on the persistence of federal subsidies for wind. Specifically, we estimate the implied price of carbon as the carbon price at which a statelevel policy would pass a state-level cost-benefit analysis, taking account of estimated greenhouse gas emission reductions and ancillary benefits from corresponding reductions in criteria pollutants. Our findings suggest that without the Production Tax Credit (federal aid), the state policy of mandating renewable power generation (RPS) is costly to state actors, with an implied cost of carbon of about $17 per ton of CO2 with a 3% discount rate. Federal aid makes the decision between natural gas and wind nearly cost neutral for Colorado.
We analytically identify two mechanisms that explain why a later arrival time for a pandemic-ending vaccine has an ambiguous effect on optimal social-distancing policy. We assess the net effect of these channels using a quantitative model solved for over a thousand parameter combinations. Optimal policy and welfare comparisons are both highly sensitive to beliefs about vaccine arrival. A policy of moving quickly to herd immunity by requiring social distancing for only the most vulnerable might be loosely justified for expected vaccine arrivals over 2 years, but becomes catastrophic if the expected arrival is within a year.
| INTRODUCTIONExpectations about the time needed to develop and distribute a COVID-19 vaccine evolved quickly during the first year of the pandemic. An informal survey of experts from February 2020 concluded that developing, licensing, and manufacturing a vaccine within 12 months would be remarkable, even revolutionary (Kormann, 2020). In July, a formal expert elicitation put September 2021 as the best guess for widespread public access (Kane et al., 2020). Many also recognized that a vaccine might prove elusive, as it has for other important diseases, such as AIDS and the common cold. In the end, the vaccine arrived faster than expected, with Britain becoming the first Organisation for Economic Cooperation and Development country to approve a vaccine on December 3, 2020.At least since Yaari (1965), economists have understood the relation between discounting and the expected time of an event that ends a problem: death in Yaari's setting and vaccine arrival in the epidemic context. Earlier expected arrival makes the future less extensive and therefore less important, having qualitatively the same effect on optimal planning as a higher discount rate. Nevertheless, the impact of vaccine arrival in a Susceptible-Infected-Removed
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.