An assessment of the cost effectiveness of vegetation harvesting as a means of removing nutrient and metals from ponds

This paper reports on an investigation to quantify the mass of pollutants removed from a stormwater retention pond by routine vegetation harvesting. The amount of plants can increase the costs of ponds, and the increased costs of plant maintenance may not be justified by enhanced pollutant removal. This study provides some of the basic information, previously lacking, which is needed to come to such decisions. The study facility was La Costa pond, a retention pond in California used to treat highway runoff. Water quality monitoring data indicate that the pond removed 43 percent of the total nitrogen entering the facility, with 5 to 7 percent directly attributable to harvesting the vegetation – in this case cattails (Typha). The data also indicate that 48 percent of the total annual phosphorus was removed from the runoff, with the harvested vegetation responsible for between 3 and 8 percent. Metal uptake by the vegetation was substantially less than nutrients. Total removal of copper, lead and zinc by the pond varied between 57 and 93 percent, with the harvested vegetation accounting for less than 2 percent of removal. Issues addressed in the paper include the cost implications of harvesting and ways of improving vegetative pollutant removal

Deterministic Dynamics in the Minority Game

The Minority Game (MG) behaves as a stochastically perturbed deterministic system due to the coin-toss invoked to resolve tied strategies. Averaging over this stochasticity yields a description of the MG's deterministic dynamics via mapping equations for the strategy score and global information. The strategy-score map contains both restoring-force and bias terms, whose magnitudes depend on the game's quenched disorder. Approximate analytical expressions are obtained and the effect of `market impact' discussed. The global-information map represents a trajectory on a De Bruijn graph. For small quenched disorder, an Eulerian trail represents a stable attractor. It is shown analytically how anti-persistence arises. The response to perturbations and different initial conditions are also discussed.Comment: 16 pages, 5 figure

From market games to real-world markets

This paper uses the development of multi-agent market models to present a unified approach to the joint questions of how financial market movements may be simulated, predicted, and hedged against. We examine the effect of different market clearing mechanisms and show that an out-of-equilibrium clearing process leads to dynamics that closely resemble real financial movements. We then show that replacing the `synthetic' price history used by these simulations with data taken from real financial time-series leads to the remarkable result that the agents can collectively learn to identify moments in the market where profit is attainable. We then employ the formalism of Bouchaud and Sornette in conjunction with agent based models to show that in general risk cannot be eliminated from trading with these models. We also show that, in the presence of transaction costs, the risk of option writing is greatly increased. This risk, and the costs, can however be reduced through the use of a delta-hedging strategy with modified, time-dependent volatility structure.Comment: Presented at APFA2 (Liege) July 2000. Proceedings: Eur. Phys. J. B Latex file + 10 .ps figs. [email protected]

Reuniting Old Allies: A Case for Creative Composition

Since the split between creative writing and composition that largely occurred in the late 1920s, the two departments have wrestled with boundaries that have defined and challenged both courses. Despite the occasionally contentious relationship between creative writing and composition/rhetoric scholars, the two disciplines have served as strong allies in the past. Reuniting Old Allies argues that returning to such an alliance could provide a fruitful, blended approach to writing. This thesis traces the history of this schism from Aristotle to the modern English department, attempting to reconcile the two departments with a middle-ground approach called critical-creative composition that emphasizes the strong rhetorical strategies already present within creative writing, as well as the inherently creative nature of composition. It analyzes the textual, rhetorical, and creative strategies of each genre and demonstrates where such strategies could be implemented in a critical-creative curriculum, as well as a pedagogical outline to guide those interested in such implementation. This map includes an explication of overarching pedagogical strategies and goals, practical classroom exercises, theoretical backing for those exercises, and sample assignments

Any Time? Any Place? The impact on student learning of an on-line learning environment.

Original paper can be found at: http://www.actapress.com/Content_of_Proceeding.aspx?proceedingID=292#pages Copyright ACTA Press [Full text of this paper is not available in the UHRA]An increasing number of HE institutions are adopting virtual and managed learning environments (VLEs and MLEs), which offer flexible access to on-line learning materials all day and every day. There are multiple claims about e-learning enhancing learning and teaching (eg. [1] Britain and Liber, 1999; [2]Conole, 2002; [4]Allen, 2003; [5]Littlejohn and Higginson, 2003) such as supporting active learning, facilitative rather than didactic teaching and increased student motivation but these are not pre determined outcomes. Much depends on how lecturers use the available technology and how students respond to that use. This paper reports on a research project which has evaluated the students' own experience of on-line learning at the University of Hertfordshire. Using its own institution-wide MLE (StudyNet) academic staff at the university have been able to offer students on-line access to their study material from September 2001. Activities available for students using StudyNet include participating in discussion forums, using formative assessment materials and accessing journal articles as well as viewing and downloading courseware for each of their courses. Students were invited to participate in a questionnaire and focus groups to identify the characteristics of the on-line learning environment which benefited their learning