Simultaneous measurement of monoaromatic hydrocarbons and dicarboxylic acids in ambient air

Atmospheric aromatic hydrocarbons and dicarboxylic acids were measured simultaneously in this work. A method was developed for aromatic hydrocarbons: collection on Tenax and charcoal, thermal desorption, and gas chromatographic analysis. Another method was verified for diacids: collection on quartz filter, conversion to dibutylesters, and analysis by capillary gas chromatography; Results of aromatic hydrocarbon measurements show a very strong linear relation among all aromatic hydrocarbons, and a significant correlation between aromatic hydrocarbons and CO measured at a nearby location. This result strongly suggests that aromatic hydrocarbons originate from automobiles. After correcting for dilution effects by normalizing hydrocarbon concentrations by CO concentration, the observed decrease in the normalized daytime concentrations indicates that atmospheric aromatic hydrocarbons undergo photochemical destruction during the daytime; Results of diacid measurements show a complex diurnal variation in concentrations. The diacids measured possibly came from either local production and/or emissions, resuspension, or from long-range transport from other areas

The Behavior of Savings and Asset Prices When Preferences and Beliefs Are Heterogeneous

Movements in asset prices are a major risk confronting individuals. This paper establishes new asset pricing results when agents differ in risk preference, time preference and/or expectations. It shows that risk tolerance is a critical concept driving savings decisions, consumption allocations, prices and return volatilities. Surprisingly, due to the equilibrium risk sharing, the precautionary savings motive in the aggregate can vastly exceed that of even the most prudent actual agent in the economy. Consequently, a low real interest rate, resulting from large aggregate savings, can prevail with reasonable risk aversions for all agents. One downside of a large aggregate savings motive is that savings rates become extremely sensitive to output fluctuation. Thus, the same mechanism that produces realistically low interest rates tends to make them unrealistically volatile. A powerful isomorphism allows differences in time preference and expectations to be swept away in the analysis, yielding an equivalent economy whose agents differ merely in risk aversion. These results hold great potential to simplify the analysis of heterogeneous-agent economies, as we demonstrate in quantifying how asset prices move and bounding their volatilities. All results are obtained in closed form for any number of agents possessing additively separable preferences in an endowment economy.

The Behavior of Savings and Asset Prices When Preferences and Beliefs are Heterogeneous

Movements in asset prices are a major risk confronting individuals. This paper establishes new asset pricing results when agents differ in risk preference, time preference and/or expectations. It shows that risk tolerance is a critical concept driving savings decisions, consumption allocations, prices and return volatilities. Surprisingly, due to the equilibrium risk sharing, the precautionary savings motive in the aggregate can vastly exceed that of even the most prudent actual agent in the economy. Consequently, a low real interest rate, resulting from large aggregate savings, can prevail with reasonable risk aversions for all agents. One downside of a large aggregate savings motive is that savings rates become extremely sensitive to output fluctuation. Thus, the same mechanism that produces realistically low interest rates tends to make them unrealistically volatile. A powerful isomorphism allows differences in time preference and expectations to be swept away in the analysis, yielding an equivalent economy whose agents differ merely in risk aversion. These results hold great potential to simplify the analysis of heterogeneous-agent economies, as we demonstrate in quantifying how asset prices move and bounding their volatilities. All results are obtained in closed form for any number of agents possessing additively separable preferences in an endowment economy

Essays on Risk Sharing and Pricing

Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, 2012.Cataloged from PDF version of thesis.Includes bibliographical references.This thesis consists of three chapters in asset pricing. Chapter 1 considers an international asset pricing setting with traded and non-traded out puts. It shows that output fluctuations in nontraded industries are a central risk factor driving asset prices in all countries. This is because nontraded industries entail a growth risk that is mostly non-diversifiable, and constitute the largest component of gross domestic product (GDP) of a country. Supportive empirical evidences include; (i) the effect of an industry's growth volatility on the interest rate increases significantly with its non-tradability and (ii) carry trade strategies employing currency portfolios sorted on nontraded output growth volatility earns a sizable mean return and Sharpe ratio for US investors. Chapter 2 considers heterogeneous-agent setting in which agents differ in risk preference, time preference and/or expectations. It shows that, because of equilibrium risk sharing, the precautionary savings motive in the aggregate can vastly exceed that of even the most prudent actual agent in the economy. Consequently, a low real interest rate, resulting from large aggregate savings, can prevail with reasonable risk aversions for all agents. However, as savings rates become extremely sensitive to output fluctuation when savings motive is large, tie same mechanism that produces realistically low interest rates tends to make them unrealistically volatile. A powerful isomorphism allows differences in time preference and expectations to be swept away in the analysis, yielding an equivalent economy whose agents differ merely in risk aversion. Chapter 3 considers a novel tractable and structural pricing framework. It shows that any risk-neutral statistical distribution of state variables can be consistently tied to the economic contents of the underlying pricing model. It establishes this structural linkage by requiring that the economy's stochastic discount factor (SDF) be a proper but unspecified function of the state variables. Consequently, the structural content of the economy as characterized by the SDF can he determined from state variables dynamics through a simple linear differential equation. As a result, state variables' distribution in physical measure can also be recovered,by Ngoc-Khanh Tran.Ph.D

Rare Disasters and Risk Sharing with Heterogeneous Beliefs

Although the threat of rare economic disasters can have large effect on asset prices, difficulty in inference regarding both their likelihood and severity provides the potential for disagreements among investors. Such disagreements lead investors to insure each other against the types of disasters each one fears the most. Due to the highly nonlinear relationship between consumption losses in a disaster and the risk premium, a small amount of risk sharing can significantly attenuate the effect that disaster risk has on the equity premium. We characterize the sensitivity of risk premium to wealth distribution analytically. Our model shows that time variation in the wealth distribution and the amount of disagreement across agents can both lead to significant variation in disaster risk premium. It also highlights the conditions under which disaster risk premium will be large, namely when disagreement across agents is small or when the wealth distribution is highly concentrated in agents fearful of disasters. Finally, the model predicts an inverse U-shaped relationship between the equity premium and the size of the disaster insurance market.