Modeling Photosynthesis of \u3ci\u3eSpartina alterniflora\u3c/i\u3e (Smooth Cordgrass) Impacted by the Deepwater Horizon Oil Spill Using Bayesian Inference

To study the impact of the Deepwater Horizon oil spill on photosynthesis of coastal salt marsh plants in Mississippi, we developed a hierarchical Bayesian (HB) model based on field measurements collected from July 2010 to November 2011. We sampled three locations in Davis Bayou, Mississippi (30.375 degrees N, 88.790 degrees W) representative of a range of oil spill impacts. Measured photosynthesis was negative (respiration only) at the heavily oiled location in July 2010 only, and rates started to increase by August 2010. Photosynthesis at the medium oiling location was lower than at the control location in July 2010 and it continued to decrease in September 2010. During winter 2010-2011, the contrast between the control and the two impacted locations was not as obvious as in the growing season of 2010. Photosynthesis increased through spring 2011 at the three locations and decreased starting with October at the control location and a month earlier (September) at the impacted locations. Using the field data, we developed an HB model. The model simulations agreed well with the measured photosynthesis, capturing most of the variability of the measured data. On the basis of the posteriors of the parameters, we found that air temperature and photosynthetic active radiation positively influenced photosynthesis whereas the leaf stress level negatively affected photosynthesis. The photosynthesis rates at the heavily impacted location had recovered to the status of the control location about 140 days after the initial impact, while the impact at the medium impact location was never severe enough to make photosynthesis significantly lower than that at the control location over the study period. The uncertainty in modeling photosynthesis rates mainly came from the individual and micro-site scales, and to a lesser extent from the leaf scale

Comparisons of Regression Tree Models For Sub-Pixel Imperviousness Estimation In a Gulf Coast City of Mississippi, USA

We studied the impact of shaded impervious surface area (ISA), atmospheric correction, and seasonal sensitivity, which have been generally ignored in previous studies, on ISA estimation at the sub-pixel scale using regression tree modelling. The study area is Pascagoula City on the Mississippi Gulf Coast, USA. Results showed that inclusion of shaded ISA as the response variable improved the model performance by reducing average error (AE) from 10.17 to 9.36%. Modelling with model-based atmospherically corrected imagery as predictors further reduced AE to 9.27%. The regression tree model using summer imagery as predictors (summer model) finally improved AE to 8.56%, compared with 9.28%, 9.50%, and 8.80% when using early spring, late spring, and autumn images as predictors, respectively; therefore the summer model was considered the optimal model. It was further applied to other seasonal images (i.e. early spring, late spring, and autumn images, as predictors) and the AE was 9.93%, 10.09%, and 9.12%, respectively, showing low seasonal sensitivity within this region. The findings in our study improved the modelling accuracy and expanded the scope of its future application in ISA estimation. © 2014 Taylor & Francis

Optimal Insurance Under the Insurer's VaR Constraint

In this paper, we impose the insurer's Value at Risk (VaR) constraint on Arrow's optimal insurance model. The insured aims to maximize his expected utility of terminal wealth, under the constraint that the insurer wishes to control the VaR of his terminal wealth to be maintained below a prespecified level. It is shown that when the insurer's VaR constraint is binding, the solution to the problem is not linear, but piecewise linear deductible, and the insured's optimal expected utility will increase as the insurer becomes more risk-tolerant. Basak and Shapiro (2001) showed that VaR risk managers often choose larger risk exposures to risky assets. We draw a similar conclusion in this paper. It is shown that when the insured has an exponential utility function, optimal insurance based on VaR constraint causes the insurer to suffer larger losses than optimal insurance without insurer's risk constraint.

Optimal insurance under the insurer's risk constraint

In this paper, we impose the insurer's risk constraint on Arrow's optimal insurance model. The insured aims to maximize his/her expected utility of terminal wealth, under the constraint that the insurer wishes to control the expected loss of his/her terminal wealth below some prespecified level. We solve the problem, and it is shown that when the insurer's risk constraint is binding, the solution to the problem is not linear, but piecewise linear deductible. Moreover, it can be shown that the insured's optimal expected utility will increase if the insurer increases his/her risk tolerance.

Institutional environment, ownership and firm taxation

This paper examines how ownership type and institutional environment affect firm taxation. Using a sample of Chinese-listed firms from 1999 to 2006, we find that private firms enjoy a lower effective tax rate than local state-owned enterprises. In addition, the preferential taxation of private firms is associated with local government incentives to promote local economic growth. We find that private firms located in regions with a lower level of privatization receive preferential tax treatment. Our results also suggest that decentralization and interjurisdictional competition lead to financial interdependence between local governments and private firms

Is China's Economic Growth Extraordinar or Mediocre? The Role of the Exchange Rate

Results derived from evaluations using different measures for China's economic growth are divergent, especially when the RMB exchange rate has experienced large depreciation. Focusing on the changes in the RMB exchange rate matching the demands of economic development, we offer some plausible explanations for the variations in the evaluation results. The significant gaps between different economic performance evaluation results before the mid-1990s, and evidence from international comparisons of factor productivity indicate that the quality of economic growth in China is different from that of other economies. Evaluation of economic development should take into account both quantitative expansion and qualitative improvement. From this perspective, evaluation results indicate qualitative improvement in the Chinese economy after the mid-1990s. Copyright (c) 2008 The Authors. Journal compilation (c) 2008 Institute of World Economics and Politics, Chinese Academy of Social Sciences.

What drives regional differences in the stock market wealth effect in China?

This article investigates the determinants of stock market wealth effect across regions. Using panel data from China, we find that the stock market wealth effect is more prevalent in regions with more stockholders, regions in which households have higher levels of stock ownership and regions in which households have lower incomes

Trade Credit, Cash Holdings, and Financial Deepening: Evidence from a Transitional Economy

This paper investigates the effect of financial deepening on the relationship between trade credit and cash holdings among Chinese listed firms. We first document an asymmetric effect of trade payables and receivables on cash holdings, in that firms hold an additional $0.71 of cash for every$1 of credit payable but use $1 of receivables as a substitute for only$0.15 of cash. We then find that firms in regions with higher levels of financial deepening hold less cash for payables while substituting more receivables for cash. A more highly developed financial sector helps firms to better use trade credit as a short-term financing instrument. Finally, we find that the ratio at which receivables are substituted for cash increased following the implementation of the new receivables pledge policy in 2007, which allowed firms to use receivables as security for loans. This policy event represents an exogenous shock that mitigates the endogeneity concern

Can GARCH-class models capture long memory in WTI crude oil markets?

This paper investigates the issue whether GARCH-type models can well capture the long memory widely existed in the volatility of WTI crude oil returns. In this frame, we model the volatility of spot and futures returns employing several GARCH-class models. Then, using two non-parametric methods, detrended fluctuation analysis (DFA) and rescaled range analysis (R/S), we compare the long memory properties of conditional volatility series obtained from GARCH-class models to that of actual volatility series. Our results show that GARCH-class models can well capture the long memory properties for the time scale larger than a year. However, for the time scale smaller than a year, the GARCH-class models are misspecified.Crude oil markets GARCH-class models Detrended fluctuation analysis Rescaled range analysis Long memory