Transferable belief model for decision making in thevaluation-based systems

We present a decision support system which is based on the transferable belief model (TBM), a model to represent someone's degree of belief based on belief functions. The system performs reasoning and decision making by integrating a system for belief propagation and a system for Bayesian decision analysis. The two subsystems are developed within the framework of the valuation-based systems. They are connected through the pignistic transformation as described in the context of the TBM. The system takes as inputs the user's beliefs and utilities, and suggests either the optimal decision or the optimal sequence of decisions. An example concerning a nuclear waste disposal problem is given to demonstrate the applicability of the system in a real-world domain     

Optimal control of (bio-)chemical reactors: generic properties of time and space dependent optimization

This paper deals with the optimal control (OC) in the space domain of (bio-)chemical reactors. As an example, the determination of optimal heat exchanger temperature profiles of exothermic tubular reactors under the assumption of steady-state and plug flow characteristics is investigated. To enable a trade-off between process performance and energy loss a weighted cost criterion is defined. Application of the Minimum Principle of Pontryagin leads to extremal control profile structures which are very similar to those obtained during optimization (in the time domain) of well mixed bioreactors. The latter problem has been analyzed in detail over the last two decades. The analogy is reflected at various levels during analytical optimal control computations.     

Architecture and Dispersal

To close the issue, guest-editors Rafi Segal and Els Verbakel curated a discussion with Stan Allen, Margaret Crawford, Marcel Smets and Sarah Whiting, and put some provocative questions to them: What constitutes public space in the contemporary city? Can the public sphere still exist in the urban context? Should public space be fought for by architects and urban designers? Or, as Allen proposes, is it the landscape architects alone who have been quick to realise the potential of the empty spaces in our cities as a ripe terrain for change? Copyright © 2008 John Wiley & Sons, Ltd.     

Dynamic modeling of filamentous bulking in lab-scale activated sludge processes

For years now, biological wastewater treatment plants rely on activated sludge systems in which a complex ecosystem, constituted mainly of bacteria and protozoa, (bio)degrade the incoming pollutants. Filamentous bulking, a phenomenon in which the filamentous organisms dominate the activated sludge is still a widespread problem in the operation of activated sludge processes with often severe economic and environmental consequences. Image analysis offers promising perspectives for early detection of filamentous bulking because the morphology parameters of the activated sludge respond rather fast to changing process conditions. This paper aims at exploiting this information in black box models to predict the evolution of the sludge volume index (SVI), a laboratory measurement currently exploited to quantify the sludge settleability. More specifically, dynamic ARX models are investigated as a function of organic loading and digital image analysis information (such as the total filament length per image and some representative mean floc shape parameters). The model’s performances are compared on the basis of a squared errors like quality criterion. While the identification results are very promising, the validation of the models on other independently generated data sets, depends on which data set is used for identification. The best performing models have (a combination of) the total filament length, one of the floc elongation parameters and the fractal dimension as inputs.     

Membrane glycoprotein changes in primary mammary tumors associated with autonomous growth

Primary and transplanted mammary tumors of the GR mouse were explanted in tissue culture and grown in the presence of radioactive fucose. Labelled membrane glycopeptides were isolated and compared by cochromatography with differentially labelled glycopeptides from normal mammary gland tissue. Differences with controls in the glycopeptide elution profiles were observed in autonomous, hormone-independent tumors but were absent in histologically similar tumors which required a continuous hormonal stimulus for growth. The results suggest that alterations in membrane glycopeptides are associated with the capacity of autonomous, hormone-independent growth of murine adenocarcinoma cells.     

The effect of nicotine on DNA repair in adult myocytes

Recent findings have demonstrated that terminally differentiated adult ventricular myocytes are capable of repairing DNA that has been damaged by exposure to oxygen free radicals. Despite the potential importance of DNA repair in cells that may survive many decades after injury, little is known about the mechanisms or regulation of repair. Since tobacco use has a well-defined role in the epidemiology and pathophysiology of heart disease, we tested the effects of nicotine on repair of free radical damaged plasmids by whole-cell protein extracts from adult myocytes. Exposure to a concentration of 25 microM nicotine increased incorporation of (32P)dCTP into damaged plasmids by 16%, and 50 or 100 microM nicotine increased incorporation by 32%. Nicotine did not alter the rate or amount of poly (ADP-ribose) on the major protein acceptor of molecular weight 113-116 kDa. Inhibition of DNA polymerase activity with pyridoxal 5'-phosphate revealed greater plasmid degradation in the presence of nicotine. We conclude that nicotine enhances DNA degradation and the increased repair is a consequence of this greater degradation.     

Definition of realistic disturbances as a crucial step during the assessment of resilience of natural wastewater treatment systems

Natural wastewater treatment systems (WWTSs) for urban areas in developing countries are subjected to large fluctuations in their inflow. This situation can result in a decreased treatment performance. The main aims of this paper are to introduce resilience as a performance indicator for natural WWTSs and to propose a methodology for the identification and generation of realistic disturbances of WWTSs. Firstly, a definition of resilience is formulated for natural WWTSs together with a short discussion of its most relevant properties. An important aspect during the evaluation process of resilience is the selection of appropriate disturbances. Disturbances of the WWTS are caused by fluctuations in water quantity and quality characteristics of the inflow. An approach to defining appropriate disturbances is presented by means of water quantity and quality data collected for the urban wastewater system of Coronel Oviedo (Paraguay). The main problem under consideration is the potential negative impact of stormwater inflow and infiltration in the sanitary sewer system on the treatment performance of anaerobic waste stabilisation ponds.     

MoS2/MoTe2 Heterostructure Tunnel FETs Using Gated Schottky Contacts

2D transition metal dichalcogenide based van der Waals materials are promising candidates to realize tunnel field effect transistors (TFETs) with a steep subthreshold swing (SS) for low‐power applications. Their atomically flat, self‐passivated layers offer potentially defect free interlayer tunneling. There are still several issues that need to be addressed to experimentally achieve a steep SS, e.g., the Schottky contacts, impact of thick layers, and device architecture with respect to gate configuration. This paper resolves these challenges by experimentally demonstrating MoS₂/MoTe₂ TFETs and their electrical characteristics, in conjunction with ab initio simulations and surface Kelvin probe microscopy. The Schottky barrier's effect at the contact regions are isolated by fabricating individual buried gates below the contacts. Devices with different top and bottom gate configurations are produced to understand the impact of gate placement on the heterostructure characteristics. Quantum transport simulations are performed on MoS₂/MoTe₂ multilayer stack to evaluate the impact of multiple layers on TFET performance, effect of gate placement, and the mechanism behind indirect tunneling over the heterojunction region. This work highlights the influence of the Schottky contacts, multiple layers and the role of different gate configurations on the band‐to‐band tunneling phenomenon in 2D heterojunction TFETs.     

pH in human tumor xenografts and transplanted rat tumors: effect of insulin, inorganic phosphate, and m-iodobenzylguanidine

Various strategies to improve the therapeutic index of anticancer agents aim at inducing, by stimulation of aerobic glycolysis, temporary pH differences between malignant and normal tissues which can be exploited to activate cytotoxic agents selectively in tumors. We have investigated whether the pH reduction induced by glucose, the "drug" commonly used to increase lactic acid production in malignant tissues, can be augmented by pharmacological manipulation of tumor cell glycolysis. At normal plasma glucose concentration (6 +/- 1 mM), inorganic phosphate, a modifier of hexokinase and phosphofructokinase activity, had no effect on pH in two transplanted rat tumors and a human tumor xenograft line (average pH, 6.80; range, 6.65-6.95). When plasma glucose concentration was raised to 30 +/- 3 mM by i.v. infusion of glucose, inorganic phosphate reduced the pH in those tumors which exhibited only a moderate pH response to glucose per se (mean pH, 6.60) to an average value of 6.20 (range, 6.05-6.35). In the same setting, insulin, continuously infused at dose rates up to 600 milliunits/kg body weight/min, did not result in acidification of tumor tissue exceeding that induced by glucose alone. However, the H+ ion activity in both transplanted rat tumors and human tumor xenografts was increased by m-iodobenzylguanidine (MIBG), an inhibitor of mitochondrial respiration. For example, at normoglycemia, MIBG reduced the mean pH in a human mesothelioma xenograft from 6.90 to 6.70. This pH value was further reduced to 6.20 by simultaneous low-dose i.v. glucose infusion (plasma glucose concentration, 14 +/- 3 mM). The acidosis induced by inorganic phosphate and MIBG was tumor specific. Normal tissues of tumor-bearing hosts were only marginally sensitive to hyperphosphatemia or MIBG administration. These results indicate that the known stimulatory effect of exogenous glucose on lactic acid production in malignant tumors in vivo can be further accentuated or, as in the case of MIBG, partially replaced by pharmacological manipulation of aerobic glycolysis using clinically established drugs.     

Estimating biomass yield coefficients for autotrophic ammonia and nitrite oxidation from batch respirograms

Kinetic characterization of biological processes via batch respirometry requires an accurate estimate of the biomass yield coefficient because it provides the stoichiometric link between biomass synthesis, substrate consumption and oxygen uptake. Expressions for biomass yield coefficients describing autotrophic ammonia and nitrite oxidation were derived from a mechanistically based electron balanced equation. We demonstrate that applying the conventional expression used to calculate the heterotrophic biomass yield results in erroneous estimates for the autotrophic biomass yield. Yield coefficients for autotrophic NH4(+)-N to NO2(-)-N oxidation and NH4(+)-N to NO3(-)-N oxidation were overestimated by 27 to 36%. Due to correlation between the maximum specific growth rate and the biomass yield, the error in yield values propagated in 30 to 40% overestimates of the maximum specific growth rate coefficient for NH4(+)-N oxidation determined from batch respirograms. Therefore, it is essential to employ the correct expression to estimate the autotrophic biomass yield coefficient from batch respirograms due its inadvertent impact on subsequent parameter estimation.