Butyltin Species and Inorganic Tin in Water and Sediment of the Detroit and St. Clair Rivers

Water and sediment samples from 29 locations in the Detroit and St. Clair rivers were analyzed for the highly toxic tri-n-butyltin (Bu₃Sn⁺) species and for the less toxic di-n-butyltin (Bu₂Sn²⁺) and n-butyltin (BuSn³⁺) species and inorganic tin. In general, locations sampled in the St. Clair River were less contaminated with butyltin species than those in the Detroit River. Inorganic tin and BuSn³⁺ were detected in over 90% of all subsurface water samples, while Bu₂Sn²⁺ and Bu₃Sn⁺ were detected in 45 and 28% of the same samples, respectively. The highest concentration ofBu₃Sn⁺ in subsurface water, 5.9 × 10^?10 mol Sn/L, was at the mouth of the Ecorse River, a tributary of the Detroit River. The three butyltin species and inorganic tin were also detected in 23–46% of all sediment samples. The highest concentrations of Bu₃Sn⁺ in sediment were found close to the mouths of the River Rouge, another tributary of the Detroit River, and the Ecorse River, and were 6.2 × I0^–7 and 1.7 × I0^–7 mol Sn/kg dry weight, respectively, for the top 2 cm of sediment.     

The Northern Ireland Civil Service

Although cursory examination reveals that one must refer to 'British civil services', a lacuna has persisted in the literature since Gladden's (1967) seminal work. Invariably, the tendency is to accord the Northern Ireland Civil Service (NICS) footnote status. This article seeks to remedy this deficiency. It offers a resum of the political context of Northern Ireland before concentrating upon NICS itself—its characteristics and changing nature in terms of public administration and the management of public policy since 1970.     

A comparison of commonly used hydrologic design methods for rainwater collectors

Rainwater collection as a possible water source in developing countries is introduced. The major parameters in calculating the size of the tank are defined. Six methods that have been used previously to relate demand, storage, reliability and the rainfall pattern are compared to the Ottawa Model over a wide range of demands.     

灯泡式机组的零停机在线监测系统

在巴西伊加拉帕瓦水电站,通过监测电气气隙,避免了一台新水轮发电机发生重大破坏和昂贵的停机事故.     

Testing for Unit Roots with Breaks: Evidence on the Great Crash and the Unit Root Hypothesis Reconsidered

Nelson and Plosser (1982), in a classic paper, failed to find strong evidence against the null hypothesis of a generating process with a unit autoregressive root for thirteen US macroeconomic time series. Perron (1989) claimed that such evidence was available for a majority of these series if the alternative hypothesis was of trend stationarity with a break in 1929. Zivot and Andrews (1992) treated the break date as endogenous, then finding strong evidence agcainst the null for a minority of these series. Our own analysis extends theirs by permitting a break under the null as well as the alternative hypothesis, and allowing for the sequential nature of the testing. Our empirical findings complete the circle. We find no strong evidence against the unit root hypothesis for any of the thirteen Nelson–Plosser series.     

在衰退中成长

如今,全球都笼罩在经济衰退之中.如果下一个就要轮到贵公司,你该怎么办?当然你要尽力保证企业财务的稳定.但更重要的是,你还必须了解公司在衰退结束后的目标设计.如果你知道企业的发展方向和如何实现这一目标,那么衰退时期是改善公司相对战略地位的好时机.     

New Directions in Water Research: IWMI at the Threshold of the Twenty-first Century

The International Water Management Institute (IWMI) has made important changes in the thrust of its research programmesince 1995. These new thrusts include attention to the implications of increasing water scarcity at the global level; the adoption of a river basin paradigm leading to new insights into opportunities for water conservation and productivity; application of new information technologies and quantitative analytical techniques; and a stronger focus on policy, institutional issues, health and environment, and social inequities in access to water. This paper describes these changes and provides an overview of the remaining papers in this special issue of Water Resources Development.     

Contract modifications and the basis behavior of live cattle futures

The purpose of this study was to assess the basis behavior of the Live Cattle Futures contract at the Chicago Mercantile Exchange (CME) before and after the 1995 contract changes. Additionally, an alternative method of basis calculation utilizing weighted mean futures prices versus settlement futures prices was compared to determine which method provides a better representation of the basis level. Within a regression model with heteroskedascity error framework, we found that the level of nearby basis in the period after June 1995 has shifted lower and the average monthly open interest of net commercial long positions has substantially increased after the contract modifications. These empirical results are consistent with the notion that more long activity entered the market in response to the contract modifications. Additionally, an alternative (new) measure of basis calculation (cash price minus weighted mean futures price) produced similar results to two other commonly used measures. In conclusion, the 1995 contract changes have neither increased nor decreased the volatility of live cattle basis. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:557–590, 2004