Application of a leakage model to assess exfiltration from sewers.

The exfiltration of wastewater from sewer systems in urban areas causes a deterioration of soil and possibly groundwater quality. Beside the simulation of transport and degradation processes in the unsaturated zone and in the aquifer the analysis of the potential impact requires the estimation of quantity and temporal variation of wastewater exfiltration. Exfiltration can be assessed by the application of a leakage model. The hydrological approach was originally developed to simulate the interactions between the groundwater and surface water, it was adapted to allow for modelling of interactions between groundwater and sewer system. In order to approximate the exfiltration specific model parameters infiltration specific parameters were used as a basis. Scenario analysis of the exfiltration in the City of Dresden from 1997 to 1999 and during the flood event in August 2002 shows the variation and the extent of exfiltration rates.     

JETS,PLUMES AND BUOYANT JETS IN STATIC ENVIRONMENT

Turbulence represents an essential aspect in atmospheric and oceanic circulations.In particu-lar,it is a preponderant factor in the dispersion of pollutants of artificial or natural origin.Thevertical turbulent jets,plumes and buoyant jets discharging into static environment is one of themost important and basic flow patterns related with the environment pollution.These flows havenumerous important applications,for example,thrust augmentors,waste disposal plumes fromstacks and combustion systems,and significant problems of turbulent diffusion.     

A RE-EXAMINATION OF THE RELATIONSHIP BETWEEN CLOSED-END FUND DISCOUNTS AND EXPENSES

In this paper the role of expenses in explaining closed-end fund discounts is re-examined. A present value model is developed to illustrate the relationship between expenses and discounts. Earlier studies find that discounts are not related to management fees. In this paper, using a larger sample over a longer and different period and a better specification of the expense variable consistent with the model developed, discounts are found to be significantly related to expenses. The relationship between expenses and discounts holds in the presence of other control variables.     

The effects of an advertising retrieval cue on young children's memory and brand evaluations

Young children's memory for television advertising is important in order for children to recognize brands in stores and/or to recall the brand name in making a purchase request. Two experiments showed that the use of visual advertising retrieval cue (a green frog as the brand character) improved memory performance and brand evaluations. Study 1 (n = 40) showed promise in the cue's assistance in children's recalling the brand name (cued recall) from the ad memory trace. Study 2 (n = 40) contained multiple exposures to the ad, which resulted in greater free recall and in support for the cue's assistance in better access of the brand name from the ad memory trace (cued recall). Affected ad memory resulted in more favorable brand evaluations and intent to request the brand's purchase. © 1994 John Wiley & Sons, Inc.     

Economists and Data

This paper is concerned with one central question: the choice between theories, and the role played by data in that choice. It deals with the uses economists may make of data and the importance of understanding the institutional basis that gives rise to the data - an area in which labour economists have traditionally been particularly strong - and with the relevance of assumptions. It deals with the ultimate need to choose between competing theories (despite the role of conventionalism) on the basis of data rather than retreating into a comfortable 'methodological pluralism'. It considers the role of test replication, with reference to the practice in natural science (and its role there in checking scientific fraud) and concludes that, despite extensive technical problems of testing, economists have to accept a data check if the rhetoric of mathematical technicality is not to overwhelm the need to explain. Parallels are drawn with experience in physics (and the implications of the development of Chaos and Catastrophe for a naively predictionist view are noted), medicine and history (of which, it is argued, modern economists are far too neglectful).