石油价格进入更加波动的新时期

通过对油价波动的历史原因、市场内在因素和人为因素的分析可以看出，石油市场已进入一个新时期，油价将变得更加动荡，而且在波动中呈上升趋势。预计新的平均价位大体为每桶20美元。为此，石油公司应积极研究贸易策略，一方面设法使自身免受损失，另一方面还要寻求从价格波动中赢利。只有准备充分，才能够抗御油价的剧烈波动和周期性变化，进而获得生存与发展。     

Estimating Willingness to Pay for Improved Water Quality in the Presence of Item Nonresponse Bias

This article deals with the problem of item nonresponse in contingent valuation surveys using a payment-card method, by applying a grouped-data sample-selection estimation technique that is capable of imputing the missing values conditional upon a respondent's decision to answer a willingness-to-pay question. The advantage of the technique lies in its ability to utilize all of the information in the sample, permitting a more efficient estimation in the presence of item nonresponse bias. The major determinants of willingness to pay appear to be household income, number of children, education, perception of existing water quality, and identification with environmental issues.     

Granular biofilm-based anaerobic digestion: molecular biomonitoring and high-rate psychrophilic treatment of phenolic wastewater.

Two pairs of expanded granular sludge bed (EGSB) bioreactors, R1/R2 and R3/R4, were designed. R1/R2 were used for mesophilic (37 degrees C) treatment of synthetic wastewater over a 100-day trial. A successful start-up was achieved by R1 and R2, with COD removal over 90%. Both reactors were operated under identical parameters; however, increased organic loading induced a reduction in COD removal by R1, while R2 maintained satisfactory performance throughout the experiment. R3/R4 were operated at 15 degrees C throughout a 422-day trial and were used for the stabilisation of volatile fatty acid-based wastewater. Phenol was introduced to R4 at an applied loading rate of 1 kg phenol m(-3)d(-1), which was increased to 2 kg phenol m(-3)d(-1). No phenol was supplied to R3. Efficient COD conversion was recorded in both R3 and R4, thus demonstrating the feasibility of high-rate phenol degradation under psychrophilic conditions. Terminal restriction fragment length polymorphism analysis was applied to the characterisation of microbial community dynamics within each of the reactors. The results indicated a microbiological basis for the deviation, in terms of operational performance, of R1 and R2. TRFLP analyses indicated stable microbial communities in R3 and R4, but detected changes in the abundance of specific ribotypes in response to phenol mineralisation.     

Economic analysis of the impact of adopting herd health control programs on smallholder dairy farms in Central Thailand

The economic impact of adopting herd health programs for mastitis and reproduction by small-scale dairy producers of Central Thailand was assessed using a policy analysis matrix (PAM). Following a reduction in the incidence of bovine disease on adopter farms, an increase in private net profits is observed. More importantly the social costs of supporting dairy farmers is reduced; the PAM effective protection coefficient was reduced by 35% for mastitis program adopters and by 44% for reproductive program adopters, indicating improved social efficiency of dairy policy. Other indicators of efficiency and policy implications are discussed.     

THE DETERMINANTS OF AUDIT FEES: SOME EMPIRICAL MODELS

This paper proposes a model of audit fee determination based upon size and other characteristics of the auditee and the auditor, and upon whether there has been a recent change of auditor (which might lead to a low-balling effect). A novel feature of the model is that auditee size is measured in two dimensions, sales and assets, and is allowed to have a quadratic relationship with audit fee. The model was estimated for a sample of large listed UK companies for the years 1981 to 1988. The results support the low-balling hypothesis and also provide insights into the distinctive role of the Big 8 firms in the audit market.     

Herd on the Street: Informational Inefficiencies in a Market with Short-Term Speculation

Standard models of informed speculation suggest that traders try to learn information that others do not have. This result implicitly relies on the assumption that speculators have long horizons, i.e., can hold the asset forever. By contrast, we show that if speculators have short horizons, they may herd on the same information, trying to learn what other informed traders also know. There can be multiple herding equilibria, and herding speculators may even choose to study information that is completely unrelated to fundamentals.