Das Glimmen von Drähten im Zylinderfeld

Zusammenfassung Bei der untersuchten Anordnung setzte das Glimmen in der positiven Halbwelle (Strom vom Draht zum Zylinder) etwas früher ein als in der negativen Halbwelle. Mit wachsender Spannung bleibt zunächst der Mittelwert des Stromes der positiven Halbwelle größer als der der negativen Halbwelle. Bei großen Spannungen bis unmittelbar vor dem Durchschlag ist das Größenverhältnis das entgegengesetzte. Der Durchschlag selbst erfolgt in der positiven Halbwelle. Im Glimmbereich zeigen die Kurvenu=f(i) den von Holm beobachteten Buckel und außerdem Kräuselungen und Zacken.Zum Schlusse möchte ich Herrn Prof. Dr.-Ing. W. Sciz, der mir die Ausführung dieser Arbeit ermöglichte und mir viele wertvolle Ratschläge gab, meinen besten Dank aussprechen.     

The influence of training level on manual flight in connection to performance,scan pattern,and task load

This work focuses on the analysis of pilots’ performance during manual flight operations in different stages of training and their influence on gaze strategy. The secure and safe operation of air traffic is highly dependent on the individual performances of the pilots. Before becoming a pilot, he/she has to acquire a broad set of skills by training to pass all the necessary qualification and licensing standards. A basic skill for every pilot is manual control operations, which is a closed-loop control process with several cross-coupled variables. Even with increased automation in the cockpit, the manual control operations are essential for every pilot as a last resort in the event of automation failure. A key element in the analysis of manual flight operations is the development over time in relation to performance and visual perception. An experiment with 28 participants (including 11 certified pilots) was conducted in a Boeing 737 simulator. For defined flight phases, the dynamic time warping method was applied to evaluate the performance for selected criteria, and eye-tracking methodology was utilized to analyze the gaze-pattern development. The manipulation of workload and individual experience influences the performance and the gaze pattern at the same time. Findings suggest that the increase of workload has an increased influence on pilots depending on the flight phase. Gaze patterns from experienced pilots provide insights into the training requirements of both novices and experts. The connection between workload, performance and gaze pattern is complex and needs to be analyzed under as many differing conditions. The results imply the necessity to evaluate manual flight operations with respect to more flight phases and a detailed selection of performance indications.

     

Dissociation of left ventricular hypertrophy, beta-myosin heavy chain gene expression, and myosin isoform switch in rats after ascending aortic stenosis

The regulation of angiotensin II (Ang II) receptors and Ang II-induced modulation of intracellular Ca2+ concentration in cardiac cells from hearts of experimentally induced hypertensive deoxycorticosterone acetate (DOCA)-salt and control unilaterally nephrectomized (Uni-Nx) Sprague-Dawley rats was assessed. Ang II receptor density and intracellular Ca2+ concentration measurements were examined in adult ventricular myocytes and fibroblasts by radioligand binding assay and digital imaging using fura 2 methodology, respectively. Four-week DOCA-salt treatment induced hypertension associated with cardiac hypertrophy. Ang II binding studies demonstrated that adult ventricular myocytes and fibroblasts possess mainly the AT1 subtype receptor. Moreover, DOCA-salt hypertension was associated with a 1.8-fold increase in Ang II-specific binding compared with myocytes from Uni-Nx control rats. Intracellular Ca2+ responses induced by increasing Ang II concentrations (10[-12] to 10[-4] mol/L) were significantly enhanced in cardiomyocytes from DOCA-salt rats. The effects of Ang II on intracellular Ca2+ spike frequency were unaltered in cardiomyocytes from DOCA-salt-hypertensive rats. The density of AT1 subtype receptors was not modified in ventricular fibroblasts after DOCA-salt treatment. Ang II increased intracellular Ca2+ concentration similarly in ventricular fibroblasts from normal and hypertensive rats. In conclusion, DOCA-salt hypertension is characterized by an increased AT1 receptor density and intracellular calcium responses in ventricular myocytes, whereas in ventricular fibroblasts the AT1 receptor status is unaltered. These findings report for the first time the cardiac cell-specific implication of Ang II and the intracellular calcium signaling pathway stimulated by the AT1 receptor in cardiac hypertrophy in DOCA-salt-hypertensive rats.     

Struktur und Aufbau moderner Analyse-Meßeinrichtungen

Structure and modular nature of modern analytical measuring equipment . Modern analytical instrumentation exhibits excellent adaptability to a wide range of demands arising from the process concerned and the site of application. Optimization of the specific plant structure according to criteria such as performance data, reliability, and economic factors demands a versatile modular system of components for matching the sensors to the process, the process control system, the discharge locations, and the environment. In addition, functions such as handling, control, and monitoring are steadily increasing in importance.     

The Development of Pigment Printing Over the Last 50 Years

With the release of the Aridye system, 46 years ago, the Interchemical Corporation laid the foundations of modern pigment printing with a process characterised by the use of emulsion thickenings and film-forming copolymer dispersions. It is a long way from these beginnings to the high technical standard that pigment printing has reached today. Following a definition of pigment printing, its historical development is traced, the advantages and disadvantages of pigment printing are compared and reference is made to the most important ranges on the market. Four sections describing the product groups used in pigment printing, namely: pigments, binders, thickening agents and pigment printing auxiliaries follow. These deal both with the physico-chemical principles and with the selection criteria for their practical application. The section on thickening agents includes a comparison of emulsion thickenings and fully synthetic thickeners. Consideration of the substrates that are suitable for pigment printing, the different printing procedures and the requirements with regard to pretreatment and finishing complete the review.     

Angiotensin-converting enzyme and angiotensinogen gene polymorphisms and heart rate variability in twins

Decreased heart rate variability (HRV) is associated with congestive heart failure, post-myocardial infarction, ventricular arrhythmias, sudden cardiac death, and advancing age. A deletion/insertion polymorphism in the angiotensin-converting enzyme (ACE) gene and a substitution (M235T) in the angiotensinogen gene have been associated with risk for heart disease. The aim of this study was to determine the heritability of HRV and related parameters in monozygotic and dizygotic twins and to assess the influence of ACE and angiotensinogen polymorphisms. We studied 95 MZ pairs and 46 DZ pairs. We measured HRV and related parameters, ACE and angiotensinogen levels, plasma norepinephrine, ACE, and angiotensinogen genotypes. We found that HRV and related parameters were significantly influenced by genetic variability, although nonshared genetic effects were also important. Angiotensinogen and plasma norepinephrine were generally correlated with decreased HRV, whereas ACE was correlated with perturbances of normal rhythmic HRV. Nevertheless, the DD ACE genotype was associated with increased HRV (p <0.05), whereas angiotensinogen polymorphisms had no effect. We conclude that HRV and related parameters are in part heritable. Interestingly, the DD ACE genotype is associated with increased HRV.     

Feststoffbildung durch Kristallisation und Fällung

Formation of solids by crystallization and precipitation. Formation of solids from solutions can take place by crystallization or precipitation. The principal factor is the relationship between solubility and supersaturation. In crystallization, the solubility of the crystallising substance is so high that the formation of solids occurs largely in the metastable zone in the immediate vicinity of the solubility limits. Crystal growth and nucleation are functions of supersaturation. If a high supersaturation is required at low substance-specific growth rates for an adequate crystal growth, high nucleation rates and hence small crystals will result. On this basis, the authors present information for the specific design of crystallization processes. In contrast, the solubility of the precipitated product must be very low for precipitation. Direct crystal formation is possible only for substance systems of high solubility. As a rule, however, the precipitated substance is so insoluble that solids are formed via amorphous intermediates. The results of a large number of experiments show the influence of various parameters of the precipitation process on the filtrability of the precipitated product.