Water distribution systems are vulnerable to aquaterrorism (terrorism attacks on the water supply) because they are extensive, relatively unprotected, accessible, and often isolated (USEPA 2002, 2003a, Grayman, 2002; Mays, 2004). An emerging activity in the water security arena is developing methods to minimize the public health and economic impacts of a large-scale attack. An intense effort is...

Zearalenone [6-(10-hydroxy-6-oxo-trans-1-undecenyl)-ß-resorcyclic acid lactone] is a mycotoxin produced as a secondary metabolite of various Fusarium fungi (see Figure 1). ZON is also known as RAL, F-2 toxin or ZAR. Zearalenone (ZON) has been detected in a variety of cereal products such as wheat, maize, barley, oats, rice and sorghum as well as beer that has been produced with contaminated gra...

The addition of oxidants for disinfecting water can lead to the formation of potentially carcinogenic compounds referred to as disinfection byproducts (DBPs). Haloacetic acids (HAAs) are one of the most widely detected DBPs in US water utilities and some of them are regulated by the US Environmental Protection Agency (USEPA). The present study developed a method to analyze all the compounds in ...

A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple,...

[1] Significant uncertainty exists in the magnitude and variability of ammonia (NH3) emissions. NH3 emissions are needed as input for air quality modeling of aerosols and deposition of nitrogen compounds. Approximately 85% of NH3 emissions are estimated to come from agricultural nonpoint sources, which are suspected to have a strong seasonal pattern. Because no seasonal information is available...

limitations of our cognitive system? Or are errors indispensable parts of every intelligent system? From the first perspective, all errors are at best unnecessary and at worst harmful. Consider an error commonly made by children. When asked to find the sum of 1/2 and 1/3. the answer is often 2/5. This is called the freshman error of adding numerators and adding denominators {Silver. 1986). But ...

A symbol is a pattern (of physical marks, electromagnetic energy, etc.) which denotes, designates, or otherwise has meaning. The notion that intelligence requires the use and manipulation of symbols, and that humans are therefore symbol systems, has been extremely in uential in arti cial intelligence. keywords: symbol, reasoning, intelligence, representation, logic This article has two parts. W...

Xylanase is an enzyme that catalyzes the hydrolysis of 1,4-beta-D-xylosidic linkages in xylans that are constituents of hemicellulose, a structural component of plant cell walls. Arabinoxylans (also known as pentosans) are highly branched xylans that occur in wheat and rye flour. Several xylanases from fungal and bacterial sources are currently marketed for use in baking (Amfep; Pariza and John...