Stable and Accurate Artificial Dissipation

Stability for nonlinear convection problems using centered difference schemes require the addition of artificial dissipation. In this paper we present dissipation operators that preserve both stability and accuracy for high order finite difference approximations of initial boundary value problems.     

Semi-empirical approach to modeling of soil flushing: model development, application to soil polluted by zinc and copper

This paper describes a semi-empirical approach to modeling the soil flushing technology. A new mathematical model aimed at predicting the course of the continuous soil flushing process by use of the input data obtained from simple batch laboratory experiments is described in the theoretical part. An objective of the study is to apply this new model to soil polluted by zinc and copper (11949 mg kg(-1) and 1895 mg kg(-1), respectively) by flushing the soil with an ammonia nitrogen solution. A set of batch experiments provided both equilibrium and kinetic data characterizing the leaching ability of both metals. By use of the model, the optimal ammonia concentration in the flushing solution was estimated (0.6 mol L(-1)). For this concentration, validity of the model results was verified by a column experiment. The removal efficiency obtained was 44% (zinc) and 54% (copper). The model correctly predicted the period of time needed for the removal of weakly bound metal fractions as well as the estimate of the overall removal efficiency of metals from the soil during the flushing process. It has also proven that it is possible to use the column experiment for model calibration through the modification of the input data. Agreement of the model and experimental results can be further improved this way.     

Mass transfer coefficients for arranged packings with vertical walls under gas film control

Packings with vertical walls, especially structured packings, are distinguished by their high efficiency and low pressure drop per mass transfer unit. Yet for these types of packings there is still no universal relationship for calculating gas-film-controlled mass transfer coefficients. The present work proposes such an equation. For arranged and structured packings the new equation fits the experimental data, both new results and those taken from the literature, with a mean error of 9%.     

Self-rated health among cardiovascular drug users in a study of Swedish twins

Fear can be elicited by physically-presented explicit threat stimuli or by more static contextual stimuli that are not an immediate source of danger. Research in both humans and animals suggest that fear produced by these two types of stimuli represents separate processes mediated by different brain structures. The present study used the startle reflex methodology to examine affective responses elicited by an explicit threat cue signalling a period of shock anticipation and by two types of contextual stimuli; darkness and attaching the shock electrodes. As expected, shock anticipation potentiated startle (fear-potentiated startle). Startle was also facilitated by darkness and by the placement of shock electrodes. Further, darkness increased fear-potentiated startle to an explicit threat cue, but did not affect the facilitation of startle produced by attaching the shock electrodes. It is suggested that affective responses to contextual stimuli should be considered when investigating both normal and pathological fear.     

Performance characteristics of a packing with boundary layer turbulizers. III. Liquid film controlled mass transfer

Liquid film controlled mass transfer in a novel design of a honeycomb packing (Turbo-Pack) with turbulizers in the region of the boundary layer has been studied. For comparison, packings without turbulizers have also been investigated. Dimensionless equations for evaluation of mass transfer are proposed and their constants have been analyzed statistically. It is shown that the presence of turbulizers leads to an increase of the mass-transfer coefficient by up to 55% and to a decrease of up to 4.5-times in the packing pressure drop per mass transfer unit. A comparison over the most effective packings known from the literature shows that, as far as its low pressure drop per mass transfer unit is concerned, the novel packing is superior to all other packings.     

Correlation between biochemical indicators of physical fitness and age

16 men in the average age of 23.7 years and 24 juniors in the average of 17 years, ice-hockey players, were investigated. A significant negative correlation between the physical fitness and indicators of lipoprotein metabolism were found. This correlation proved the significance of the intensity of physical activity as a factor decreasing the risk factors of atherosclerosis. Significantly higher levels of triacylglycerols and significantly lower HDL-cholesterol were found in men when compared with the juniors. The comparison of two age categories which were subjected to regular long-term physical activity of high intensity, proved the influence of the age of ice-hockey players who had been trained under the same conditions. Both quantitative and qualitative changes in lipoprotein metabolism proved the increase in atherogeneous risks with the increasing age. (Tab. 7, Ref. 14.)     

Sensitive patient-doctor communications relating to the breasts and prostate

The authors show case of lateral cervical cyst and carcinoma of the tonsil in woman 50 years, paying attention to large diagnostic and therapeutic difficulties. After operation of the lateral cervical cyst on the left side, metastasis of tumor followed, which was operated (after negative result of the thin-needle biopsy method) and histopathological examination of the tumor didn't prove atypical cells. In a few month after operation there followed tumorous infiltration in region angle of mandibula and in tonsillar region on the side and performed the thin-needle biopsy method showed planoepithelial carcinoma of the tonsil with transitional cells, which infiltrated the lingua, fundus of the oris and lymphonodes of the neck. Next the patient was sent to further treatment in the Oncological Hospital in Lodz. In connexion with advanced of the carcinoma, the using treatment (radiotherapy Co--60 and chemotherapy) was only the palliative treatment and prolongated life of the patient about 3 years.     

Interior value extrapolation: a new method for stress evaluation during topology optimization

This article presents a new method for evaluating stresses in the jagged structures that arise when using a fixed finite element mesh to optimize the topology of a structure. The new method, Interior Value Extrapolation, IVE, exploits the fact that in the interior of the structure, the stresses calculated by the finite element method are more accurate than at the boundary. The jagged nature of the mesh makes stresses at the boundary oscillate. Therefore, stresses at the boundary are instead extrapolated from results in the interior, resulting in a more stable and accurate stress measure. A restriction method in the form of a non linear density filter is also proposed, tailored to be used in conjunction with the new stress evaluation method. The new method is evaluated for accuracy using example geometries, for which the stresses are known. It is shown that IVE improves the accuracy of the stress calculation. Optimization examples are thereafter solved with and without IVE, and the results are discussed. It is shown that the change in stress evaluation can in fact cause changes in the solution of a typical stress minimization problem.     

Attitudes toward condoms and experience with their use among sex education teachers

BACKGROUND: The sex education is influenced by knowledge and attitudes. The aim of presented study was to evaluate the attitudes toward condom among sex education teachers and their personal experience with its use. METHODS AND RESULTS: Attitudes toward condoms were measured by 10-items anonymous questionnaires according to Zv?rina and Lippert. Personal experience was subjectively assumed in 5-point scale. The samples consists of 230 sex education teachers, among them 193 (84%) women. The average age was 40.5 +/- 9.7 years, in the range from 19 to 60 years. 37 teachers (16%) assigned themselves as religious. Condom was evaluated as a good protection against HIV and other STD in almost all answers. Three fifths of teachers considered condom to be an excellent contraception. 48% teachers did not know if the majority of women dislike condom. One tenth respondents rejected the opinion that the men dislike condoms. One tenth of teachers has never experienced condom personally. 12 percent stated to use it regularly, among them are more represented men. The opinions about quality of condom and decreased sensitivity by condom differ believers from atheists and users from non-users. CONCLUSIONS: Attitudes toward condom are predominantly liberal among Czech sex education teachers. The personal experience with use is common but not regular. The religion has small influence toward the attitudes and use.