Numerical aspects of a Godunov-type stabilization scheme for the Boltzmann transport equation

Journal of Computational Electronics - We discuss the numerical aspects of the Boltzmann transport equation (BE) for electrons in semiconductor devices, which is stabilized by Godunov’s...     

Estimation of the required amount of hydrological exploration in lignite mining areas on the basis of hypothetical hydrogeological models

Mine drainage is a necessary but very costly precaution for open-pit lignite mining in sandy aquifers. Consequently, the minimization of the number of drainage wells and their optimal operation become important tasks in designing mine drainage systems. Comprehensive groundwater flow models have to be used, both, for the design of drainage wells, and for the analysis of water management strategies in mining areas. The accuracy of computations with such models depends on the precision of the underlying hydrogeological informations. In order to get these informations detailed and costly hydrogeological explorations have to be done in the mining regions. The basic informations are obtained using exploration drilling. The cost for hydrogeological exploration are approximately a linear function of the number of exploration bore holes. Therefore the reduction of drilling gets a key role in reducing costs of exploration. This might be done by:

- increased use of geophysical exploration methods,

- complex analysis of exploration results using mathematical statistical methods,

- precise estimation of the required amount of hydrogeological informations.

The paper describes a mathematical approach to support the complex decision making procedure of estimating the optimal amount of hydrogeological exploration with respect to a given mine drainage goal.     

Wirkung von Gasen auf den reaktiven Stofftransport im Mehrphasensystem Untergrund

The subsurface is a multi-phase system. The mix-phase soil-gas is beside the aqueous and the non aqueous liquid-phases the third fluid capable to occupy the pore space of the solid matrix and to flow through it. The transfer of matter between the mixphase soil-gas and the two liquid mixphases is hereby the key process of the impact of reactive gases on matter-transport in the vadose and groundwater zone. Remediation techniques – as the in situ sparging, stripping and venting – are based on these transfer-reactions. Central are hereby the reactive gases O ₂ , O ₃ , CH ₄ , NH ₃ , PH ₃ , H ₂ , CO ₂ , SO _x and NO _x acting as electron or as proton acceptors or donars, respectively, and as structural elements of cell synthesis in the subsurface. Their application during remediating the contaminated subsurface or by formating bubbler gas walls capable to clean contaminated groundwater flowing through them is of special interest. The Dresden testsite was built up to investigate problems inherent to this subject using hereby pilot-seal test equipment in in- and out-door facilities.     

What''s so funny? A comparison of students who are deaf or hard of hearing and hearing students'' appreciation of cartoons

The aim of this study was to explore the association between stressful life events (SLE) and the development of panic disorder (PD) in an Israeli sample. A total of 44 PD patients and a matched control group were studied with regard to SLE over the life cycle (in childhood, adolescence, adulthood and the year preceding the outbreak of the disorder). The major findings were as follows. (i) With regard to the total number of life events experienced in childhood and adolescence, the PD group had experienced significantly more life events than the control group. (ii) No differences were detected in the total amount of SLE between the PD group and the control group with regard to adulthood and the year preceding the outbreak of the disorder, although the PD group had more life events relating to loss in adulthood, whereas in the year before the outbreak of PD life events relating to 'love and family', negative and loss events were more prevalent. These results expand previous findings by demonstrating that SLE in childhood and adolescence may contribute to the development of PD in adulthood.     

Fraud detection in play-money prediction markets

Prediction markets are increasingly used to aggregate information on particular future events of interest such as elections, sports events, and Oscar winners. However, prediction markets are sensitive to manipulation and price distortions. In this paper, we show evidence for fraud in a play-money sports prediction market. In contrast to the often considered outcome manipulation in the context of political stock markets we were only looking for violations of our general terms and conditions, i.e., for traders creating multiple user accounts and trading against themselves in order to transfer cash from one account to another. We found evidence of suchlike coalitions and received complaints about it by annoyed traders. We discuss possible countermeasures in order to avoid or at least detect this kind of fraud in play-money prediction markets and present a tool which can be used to detect coalition building while operating a market.     

Martensite and Reverse Transformation during Complete Cycle of Simple Shear of NiTi Shape Memory Alloy

Abstract:  Investigation into the quasi-static simple shear of shape memory alloy (SMA) was carried out. A special grip was designed which allowed replacing compression into the shear process on testing machine. At the same time the shear zone temperature was observed by an infrared camera. The mechanical and thermal characteristics of sheet specimens of NiTi subjected to superelastic shear deformation due to reversible stress-induced phase transformation were clarified. By comparison of the data, the processes of martensite and reverse transformations during the shear deformation were analysed. The investigation shows that stages of the phase transformations during the simple shear process are similar like those observed during tension test. Moreover, during the simple shear deformation no uniform temperature distributions were noticed, especially at higher shear rate, manifesting that the stress-induced phase transformation during the shear process is also inhomogeneous. The thermomechanical properties of the NiTi SMA for various shear rates were investigated. It was found that an increase in the strain rate results in an increase in temperature variation, the shear stresses and the magnitude of hysteresis loops between the forward and reverse transformations.     

Randomised placebo-controlled study of atovaquone plus proguanil for malaria prophylaxis in children

BACKGROUND: The combination of atovaquone and proguanil is highly effective and safe for the treatment of Plasmodium falciparum malaria. We aimed in this randomised, double-blind, placebo-controlled study to assess the efficacy and safety of this combination for malaria prophylaxis. METHODS: 320 children who lived in a hyperendemic area for P falciparum malaria were stratified by weight and randomly assigned atovaquone plus proguanil or placebo once daily for 12 weeks. All children received initial curative treatment with atovaquone and proguanil before the start of chemosuppression. We recorded adverse events daily and collected thick blood smears once a week. The primary endpoint was a positive blood smear. FINDINGS: 25 of 140 children in the placebo group and none of the 125 children in the atovaquone plus proguanil group had positive smears during chemosuppression (p<0.001). Adverse events during the chemosuppression phase did not differ between the groups. INTERPRETATION: The combination of atovaquone plus proguanil is a highly effective and well-tolerated chemosuppressive antimalarial in children. This drug combination could replace current regimens.