Experimental study of a novel hybrid constructed wetland for water reuse and its application in Southern China

A new type of hybrid constructed wetland (CW), consisting of both vertical-baffled flow wetland (VBFW) and horizontal subsurface flow wetland (HSFW), has been deployed in Southern China to naturally accelerate the removal of organic matter and nitrogen. The hybrid CW system is characterised by a combination of continuous baffled flow vertical wetland and 'S' pattern horizontal subsurface flow wetland with natural aeration ditches to increase the concentration of dissolved oxygen in the HSFW bed. An internal circulatory system from the HSFW effluent back to the VBFW may optionally be operated to enhance the biological denitrification effect. Cyperus alternifolius is the main macrophyte in the wetland bed. The performance of the hybrid CW was studied with a pilot-scale system and three full-scale systems for municipal sewage treatment in Southern China. The results suggest that this new hybrid CW can achieve removal efficiencies of chemical oxygen demand, suspended solids, ammonia nitrogen, total nitrogen, and total phosphorus of better than 83.6, 95.0, 71.7, 64.5 and 68.1% respectively, with a specific wetland bed area of 0.70-0.93 m(2) PE(-1). The mean effluent concentrations of these parameters would meet the regulatory discharge limits for wastewater treatment systems (GB18918, 2002) and reuse in the context of agricultural irrigation solutions in China.     

Non-parametric frontier estimates of mutual fund performance using C- and L-moments: Some specification tests

There is a burgeoning literature using non-parametric frontier methods to measure mutual fund performance. These articles measure the relationship between the various characteristics (mainly return information and some costs of ownership) of these specialized financial products to establish a ranking using some efficiency measure. We argue in favor of the use of the shortage function, which is compatible with general investor preferences, and question some of the often maintained hypotheses in this line of research. The empirical part employs a large database of US and European mutual funds to offer extensive tests of the underlying modeling assumptions using various frontier estimators.     

A short-run Johansen industry model for common-pool resources: planning a fishery's industrial capacity to curb overfishing

Current methods for assessing capacity and its utilisation infisheries operate at the firm-level, but neglect industry capacity.Here, we introduce the Johansen-Färe measure of plant capacityof the firm into a multi-output, frontier-based version of theshort-run Johansen industry model. The model determines firmcapacity utilisation such that current industry outputs aremaintained, while minimising the use of fixed inputs at industrylevel and assuming abundant variable inputs. Policy extensionsrelevant to combating overfishing include tightening quotas,seasonal closures, linking economic and plant capacity, decommissioningschemes and area closures, implementation issues and equityconsiderations. The application to the Danish fisheries revealssubstantial overcapacity in the Danish fleet.     

Portfolio performance gauging in discrete time using a Luenberger productivity indicator

This paper proposes a pragmatic, discrete time indicator to gauge the performance of portfolios over time. Integrating the shortage function (Luenberger, 1995) into a Luenberger portfolio productivity indicator (Chambers, 2002), this study estimates the changes in the relative positions of portfolios with respect to the traditional Markowitz mean-variance efficient frontier, as well as the eventual shifts of this frontier over time. Based on the analysis of local changes relative to these mean-variance and higher moment (in casu, mean-variance-skewness and mean-variance-skewness-kurtosis) frontiers, this methodology allows to neatly separate between on the one hand performance changes due to portfolio strategies and on the other hand performance changes due to the market evolution. This methodology is empirically illustrated using a mimicking portfolio approach (22 and 23) using US monthly data from January 1931 to August 2007.     

Debt valuation, renegotiation, and optimal dividend policy

The valuation of debt and equity, reorganization boundaries,and firm's optimal dividend policies are studied in a frameworkwhere we model strategic interactions between debt holders andequity holders in a game-theoretic setting which can accommodatevarying bargaining powers to the two claimants. Two formulationsof reorganization are presented: debt-equity swaps and strategicdebt service resulting from negotiated debt service reductions.We study the effects of bond covenants on payout policies anddistinguish liquidity-induced defaults from strategic defaults.We derive optimal equity issuance and payout policies. The debtcapacity of the firm and the optimal capital structure are characterized.     

A Markov model for the term structure of credit risk spreads

This article provides a Markov model for the term structureof credit risk spreads. The model is based on Jarrow and Turnbull(1995), with the bankruptcy process following a discrete statespace Markov chain in credit ratings. The parameters of thisprocess are easily estimated using observable data. This modelis useful for pricing and hedging corporate debt with imbeddedoptions, for pricing and hedging OTC derivatives with counterpartyrisk, for pricing and hedging (foreign) government bonds subjectto default risk (e.g., municipal bonds), for pricing and hedgingcredit derivatives, and for risk management.     

Radial and nonradial measures of technical efficiency: An empirical illustration for Belgian local governments using an FDH reference technology

This paper serves two purposes. First, we argue that radial efficiency measures are inappropriate for the Free Disposal Hull (FDH) technology, and we provide a comparative analysis of alternative nonradial measures. In particular, using information on Belgian local government expenditures and output indicators we implement various radial and nonradial measures on the FDH reference technology, and we investigate to which extent these efficiency measures imply different distributions and rankings. Second, we analyze the patterns of measured technical efficiency implied by the various indices. Specifically, we investigate whether different measures make any substantial difference for the explanation of the calculated inefficiencies. The empirical results suggest that more important differences in rankings exist between radial and nonradial measures than between different nonradial alternatives; moreover, the radial and the nonradial efficiency measures do yield a somewhat different pattern of explanation.This is a revision of a paper presented at the 38th Conference of the Applied Econometrics Association in Athens (April 12–13, 1993). Comments of R. Goudriaan, Henry Tulkens, and two anonymous referees are gratefully acknowledged.