Continuous measurements of cardiac output in the perioperative period

Management of critically ill patients is based on knowledge of fundamental physiological variables. Automatized and continuous measurement of these variables is preferable. A new system based upon the thermodilution method has been developed to measure cardiac output automatically and continuously. We evaluated the system in the potentially unstable perioperative period with possible great and rapid changes in cardiac output. Twenty patients, scheduled for open heart or abdominal aortic aneurysm surgery, were included into the study, which was approved by the local ethical committee. The patients were monitored for up to 30 hours. At random intervals five iced bolus thermodilution cardiac output (BCO) determinations were made and compared to the continuous measurements (CCO). Two hundred and thirty-one pairs of data were obtained. The cardiac outputs ranged from 2.5-14.9 l/min. The absolute bias was 0.31 l/min (95% limits of agreement -1.4 l/min to 2.0 l/min). The mean relative error was 4.7% with a standard deviation of the relative error of 15.4%. The linear regression was represented by: CCO = 11.352 x BCO - 0.36. The correlation coefficient R was 0.90 (p < 0.001). In conclusion, the CCO measurement technique is a promising clinical method. The method is straightforward, requires no calibration, is independent of vascular geometry and measures with its limitations volumetric flow. Finally automatic and continuous patient monitoring provides more information and has potential to reveal previously undetected haemodynamic events.     

Beitrag zur asynchronen Linearmaschine mit parallelen Statorleitern und ortsabhängiger Sekundärleitfähigkeit

Übersicht Der Einfluß der Parallelschaltung der Statorleiter auf das Betriebsverhalten des asynchronen Linearmotors wird untersucht und insbesondere für den Fall verschwindender elektrischer Sekundärleitfähigkeit im Statoreintrittsbereich dargestellt. Zur Verdeutlichung werden die Ergebnisse mit denen des Linearmotors bei Reihenschaltung der Statorleiter und des umlaufenden Asynchronmotors verglichen.

---

On the performance of the linear induction machine with stator conductors in parallel and with stator dependent conductivity of the secondary

Contents The influence of connecting the stator conductors in parallel on the performance of the linear induction machine is analysed. Particularly the case of secondary conductivity zero at the entrance zone is treated. The results are compared with the performance characteristics of the linear machine the stator conductors connected in series and of the rotating induction machine.

---

---

Die Verfasser danken der Deutschen Forschungsgemeinschaft für die finanzielle Unterstützung des Forschungsvorhabens.     

Berechnung der Anlaufdaten von Asynchron-Käfigläufermotoren verschiedener Stabformen mit der Methode der finiten Differenzen

Übersicht Die spannungsabhängigen Anlaufströme und Drehmomente eines 2800 kW Asynchron-Käfigläufermotors werden mit der Methode der finiten Differenzen und einem neuen Block-SOR-Iterationsverfahren berechnet. Es wird ber die Ergebnisse für Rechteck-, Trapez- und andere Rotorstabformen berichtet. Die numerisch berechneten Daten werden mit den nach konventionellen Regeln ermittelten Zahlen verglichen. Der Sättigungseffekt ist unerwartet groß, als Folge des großen Nennstrombelages. Die ungesättigten werte stimmen sehr gut überein.

---

On the calculation of the starting data of A.C. squirrel-cage motors with different bar shapes by the method of finite differences

Contents The voltage dependent starting currents and torques of a 2,800 kW 3-phase a.c. squirrel cage motor are calculated by the method of finite differences using a new block-SOR iteration technique. The paper describes the results for different rotor bars with rectangular, trapezoidal and other shapes. The calculated data are compared with conventionally determined figures. The saturation effect is rather large due to the high values of the rated current loading per air gap periphery. The unsaturated values agree very good.

     

The geographical effects of the NAFTA on Canadian provinces

This paper investigates the effects of the North American Free Trade Agreement (NAFTA) on the Canadian provinces. A large body of research has emerged testing the effects of the Canada–US Free Trade Agreement and the NAFTA, but the majority of that research has analyzed the effect of free trade at the national scale despite the fact that different provinces have different industrial compositions and levels of integration with the US. It is found that there is a geographical component to the effect of the NAFTA, and this geographical component varies from province to province. I am grateful to Trevor J. Barnes for comments on an earlier draft of this paper.     

Reversible photoswitching enables single-molecule fluorescence fluctuation spectroscopy at high molecular concentration

We demonstrate that photoswitchable markers enable fluorescence fluctuation spectroscopy at high molecular concentration. Reversible photoswitching allows precise control of the density of fluorescing entities, because the equilibrium between the fluorescent ON- and the dark OFF-state can be shifted through optical irradiation at a specific wavelength. Depending on the irradiation intensity, the concentration of the ON-state markers can be up to 1,000 times lower than the actual concentration of the labeled molecular entity. Photoswitching expands the range of single-molecule detection based experiments such as fluorescence fluctuation spectroscopy to large entity concentrations in the micromolar range.     

Efficiency bound of a solar-driven stirling heat engine system

A solar-driven Stirling engine is modelled as a combined system which consists of a solar collector and a Stirling engine. The performance of the system is investigated, based on the linearized heat loss model of the solar collector and the irreverisible cycle model of the Stirling engine affected by finite-rate heat transfer and regenerative losses. The maximum efficiency of the system and the optimal operating temperature of the solar collector are determined. Moreover, it is pointed out that the investigation method in the present paper is valid for other heat loss models of the solar collector as well, and the results obtained are also valid for a solar-driven Ericsson engine system using an ideal gas as its engine work substance. © 1998 John Wiley & Sons, Ltd.     

Synthesis and structural characteristics of polycyclic aromatic hydrocarbon-containing phenol formaldehyde resites

To probe the formation of polycyclic aromatic hydrocarbons (PAHs) during the carbonization, gasification, and liquefaction of coals and other solid fuels, nonsoftening phenol—formaldehyde (PF) co-resites are ideal since they facilitate the incorporation of individual PAHs into a highly crosslinked matrix. A series of PAH and diphenylalkane-containing phenolic co-resites have been prepared using phenol with, as the second component, 2-naphthol, 4-hydroxy diphenylmethane, 4,4′-dihydroxydiphenylethane, 1-(4-hydroxybenzyl)naphthalene, 9-(4-hydroxybenzyl)anthracene, and 9-(4-hydroxybenzyl)phenanthrene. A mole ratio of 3 : 1 (phenol : second phenolic constituent) was adopted to ensure that a reasonably high degree of crosslinking was achieved. The virtually complete elimination of ether and methylol functions from the resoles by curing at 200°C was monitored by solid-state ¹³C-NMR. The resites were also characterized by Fourier transform infrared spectroscopy. The volatile-matter contents of the PAH-containing resites were all higher than that of the normal resite. The carbonization of the 9-(4-hydroxybenzyl)anthracene-containing resite in a fluidized-bed reactor is used to illustrate the potential applications of the PAH-containing resites in fuel science. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 663–671, 1997     

Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals

Despite considerable advances in synthesizing high-quality core/shell upconversion(UC)nanocrystals(NC;UCNC)and UCNC photophysics,the application of near-infrare...     

减少振动高速凸轮廓线修正的简易方法

凸轮从动件的多余振动将造成系统的力、噪音、磨损和工作成本增加,本文采用凸轮轮廓输入成形来减少振动,输入成形是一种实际的时间控制算法,它是为计算机控制器开发的,为了应用凸轮设计概念,必须建立某些修正算法.采用可变的工作速度和从动件动力学建造一试验装置来检验高速输入外形凸轮轮廓的效能.试验结果表明本文推荐的解决方法是有用的.