Uremia: pathophysiologic sequelae and indications for kidney replacement therapy

Mortality in intensive care unit patients with acute renal failure is still high. The reasons for this are not fully understood. Renal failure without other failing organs does not lead to death if treatment is adequate. Uremia is therefore thought to prevent spontaneous recovery from and impedes the treatment of other organ failures. The reasons for this have been elucidated only partially. Of main importance are different kinetics and dynamics of endo- and xenobiotics in uremia. The mechanisms that lead to altered kinetics in such patients are quite clearly understood, while in the field of altered dynamics many questions are open. It is also unclear which accumulating metabolites are responsible for the different dynamics. This is the reason why parameters that would indicate when to start a dialysis procedure in acute renal failure are still lacking. Exceptions are substances known to lead to death if they are present in high concentrations. These substances are mainly potassium, salt and water.     

Engineering Design Thinking,Teaching, and Learning

This paper is based on the premises that the purpose of engineering education is to graduate engineers who can design, and that design thinking is complex. The paper begins by briefly reviewing the history and role of design in the engineering curriculum. Several dimensions of design thinking are then detailed, explaining why design is hard to learn and harder still to teach, and outlining the research available on how well design thinking skills are learned. The currently most‐favored pedagogical model for teaching design, project‐based learning (PBL), is explored next, along with available assessment data on its success. Two contexts for PBL are emphasized: first‐year cornerstone courses and globally dispersed PBL courses. Finally, the paper lists some of the open research questions that must be answered to identify the best pedagogical practices of improving design learning, after which it closes by making recommendations for research aimed at enhancing design learning.     

Effects of insulin-like growth factor I combined with growth hormone on glucocorticoid-induced whole-body protein catabolism in man

Treatment with insulin-like growth factor I (IGF-I) alone failed to affect glucocorticoid-induced protein catabolism in a previous study from our laboratory. To assess the effects of the combination of IGF-I and GH in a similar protocol, 24 normal subjects received (in a double-blind, randomized, placebo-controlled manner) s.c. injections of either GH alone (0.3 IU/kg.day), the combination of IGF-I (80 micrograms/kg.day) and GH (0.3 IU/kg.day), or placebo for a period of 6 days during which they were treated with methylprednisolone (0.5 mg/kg.day). Whole-body protein kinetics measured, using the [1-13C]-leucine infusion technique, demonstrated that leucine flux (a parameter of protein breakdown) increased during administration of glucocorticoids alone (placebo group) and during GH-treatment, whereas the glucocorticoid-induced increase was abolished during IGF-I plus GH (P < 0.03 vs. GH). Leucine oxidation (a parameter of irreversible protein catabolism) increased in the placebo group (+60 +/- 14.5%, P < 0.005, day 7 vs. day 1), remained unchanged in the GH group (+2.5 +/- 10%), and decreased in the combination group (-17.7 +/- 3.3%, P < 0.002, day 7 vs. day 1). Glucose MCR decreased in the group receiving placebo (P < 0.05) and remained unchanged during combined treatment with IGF-I plus GH. It is concluded that glucocorticoid-induced protein, catabolism (leucine oxidation) is abolished during coadministration of GH (anticatabolic effect), whereas treatment with IGF-I and GH results in a net anabolic effect without adverse effects on peripheral glucose clearance.     

水电站引水隧洞钢衬砌的压曲

采用数值模拟技术，对水电站引水隧洞的钢衬砌在外水压力作用下直到破坏的结构性能进行了研究。在数值模型中采用了真实条件来考虑逐渐的弹塑性压曲和与周围介质（混凝土和岩石）的接触条件的改变。研究了各种参数（如原始缺陷，加劲件类型和间距，钢材等级等等）的影响，同Jacobsen法作了详细比较，展示了该方法的有效性和限制。     

Aerodynamic performance of a low-speed wind tunnel.

The determination of the odour mass flow emitted from a source is a very important step and forms the basis for all subsequent considerations and calculations. Wastewater treatment plants, as well as waste treatment facilities, consist of different kinds of odour sources. Unfortunately, most of the sources are passive sources, where no outward air flow-rate can be measured, but where odorants are obviously emitted. Thus, a type of sampling is required that allows to measure the emitted odour flow-rate (OFR). To achieve this, different methods are in use worldwide. Besides indirect methods, such as micrometeorological atmospheric dispersion models, which have not been used in Germany (in other countries due to different problems, direct methods are also used). Direct measurements include hood methods, commonly divided into static flux chambers, dynamic flux chambers and wind tunnels. The wind tunnel that we have been operating in principle since 1983 is different from all subsequent presented wind tunnels, in that we operate it at a considerably lower wind speed than the others. To describe the behaviour of this wind tunnel, measurement of the flow pattern in this low-speed tunnel are under way, and some initial results are presented here.     

Comparison of plasma formation in n+p and p+n and TRAPATT diodes

A numerical solution of the plasma-trapping part of the cycle for equivalent `N? and `P?-type TRAPATT diodes shows that, if the conventional criteria for plasma formation are used, the results predicted are contradictory to experimental observations. These calculations, however, do show evidence for a different physical mechanism of plasma formation, with negative electric fields, than has been assumed previously. This mechanism can help explain the observed superiority of `P?-type diodes. In addition, it is suggested that the material parameters of p?p+ epitaxial layers may be significantly different for the general run of wafers.     

Flexible finite-difference stencils from isoparametric finite elements

A new finite-difference technique for the numerical solution of boundary value problems for partial differential equations in two space variables is described. Isoparametric finite elements are used in a finite-difference context to derive difference approximations to space derivatives on a locally curvilinear grid. The result is a generalization of a classical finite-difference stencil which is ‘flexible’ in that it is adaptable to variable meshes, such as those arising from regions with curved boundaries. Numerical results presented for a test problem (potential flow past a circle) using a 9 × 10 grid agree with the analytic solution to within one per cent.