Measurements of bubble plume behaviour and flow velocity in gas stirred liquid Wood's metal with an eccentric nozzle position

The distribution of gas fraction and the flow field of gas-stirred liquid metal in steel ladles at eccentric injection of the stirring gas through the bottom of the vessel were measured in melts of 437 kg liquid Wood's metal. The melts had a temperature of 100°C. The bath height was 37 cm and the vessel diameter 40 cm. The blowing nozzle was positioned at half of the vessel radius. Gas flow rates were between 100 and 800 cm³(STP)/s. The gas fractions were measured by electrical resistance probes. The flow velocity of the liquid metal was determined by magnet-probes. The gas fraction and the velocity distribution in the plume were found to have a Gaussian shape. The cross-section of the plume is ellipsoid, as the plume width in the direction of the radius was a little smaller than the width in the direction perpendicular to it. Moreover the plume was inclined to the wall. The results which were found for the plume are mathematically described. The flow field at eccentric gas-stirring consists of one great loop, which fills almost the entire vessel. This is contrary to centric blowing, where for aspect ratios of the ladle in the order of 1, a toroid is formed in the upper and a dead zone exists in the lower part of the vessel. The consequences of this behaviour, especially for mixing in the melt, are discussed.     

Structural, chemical, and electrical characterisation of reactively sputtered WSx thin films

WS_x films were sputter-deposited on Si, SiO₂/Si, and glass substrates from a WS₂ target in an Ar/H₂S atmosphere. Their structure, morphology, chemical composition, and electrical properties were investigated as a function of deposition parameters such as working pressure and H₂S fraction. Films could be grown in the composition range WS_0.3−WS_3.5. Crystallisation was achieved at substrate temperatures T_s > 70 °C and compositions 0.7 ≤ x ≤ 1.95. While the first 5–50 nm near the interface exhibited a basal orientation (c), further growth resulted in the formation of edge-oriented platelets (c) giving rise to a porous, lamellar microstructure. The crystalline structure was mainly turbostratic, while some degree of ordered stacking was present in samples grown at high substrate temperature (600 °C). Resistivity measurements showed a semiconductor-type temperature dependence characterised by activation energies up to 95 meV. Sheet resistance was found to be nearly independent of film thickness, suggesting that the main carrier transport takes place in an interfacial layer of about 20 nm in thickness.     

Retinoic acid-dependent stimulation of 2,2''-azobis(2-amidinopropane)-initiated autoxidation of linoleic acid in sodium dodecyl sulfate micelles: a novel prooxidant effect of retinoic acid

The nursing profession places a high value on the acquisition of autonomy as a requisite for professional status. Although the literature is replete with studies that examine autonomy and nurses, methods and results often are inconsistent and inconclusive. Review of the literature reveals ambiguous or absent definitions of autonomy. Nursing commonly confuses autonomy with related concepts such as authority, accountability, power, professionalism, and independence. A concept analysis of autonomy is done using Walker and Avant's modification of Wilson's analysis procedure. This highly abstract concept emerges as a discrete, empirically definable term referring to a potential human quality in an existing state. The analysis includes antecedents, consequences, defining attributes, model and borderline cases, and empirical referents.     

Detection of nonstationarities in geological time series: Wavelet transform of chaotic and cyclic sequences

Wavelet analysis is used to detect and localize unconformities, events, or chaotic and periodic-cyclic sequences in marine sedimentary successions. Computer modeling using a single nonlinear algorithm provides a quantitative approach to a better understanding of chaotic, cyclic and monotonous sedimentation, and the preservation of unconformities. To model cyclic and chaotic sequences, we consider nonlinear and cyclic fluctuations in the rate of sedimentary supply, simple climatic feedback processes, variations of the Earth's orbit and sea-level changes. Controlled by superimposed sinusoidal fluctuations of sea-level, four stages of deterministic sedimentary pattern may be detectable: (1) chaotic sedimentation at relatively low sea-level and early transgression; (2) stable sedimentation with well-pronounced cyclicity or monotonous sequences at relatively high sea-level during late transgression and early regression; (3) a pre-chaotic zone with absence of significant cyclicity during decreasing sea-level; and (4) chaotic signals in the sea-level lowstand. These patterns have also been found in a Cretaceous sedimentary succession. Additionally, the exact localization of transitions and abrupt changes (events and unconformities) in the sequences permit a sufficient and simple zonation of the datasets. These transitions can be correlated to stratigraphical boundaries or changes in the depositional environment as well as to changes of the sedimentation rate.     

Memory effect for polarization of pump light in optically pumpedvertical-cavity semiconductor lasers

We report that the polarization of the emission of an optically pumped vertical-cavity surface-emitting laser (VCSEL) is sensitive to the polarization state of the pump light. By measuring this memory effect for circularly polarized pump light, we determine the normalized relaxation rate of the carrier spin, Γ_s, which is a vital parameter in current theoretical models of VCSEL polarization. We find Γ_s=300±150, a value which is significantly larger than previously estimated. We also observe a memory effect for the orientation of linearly polarized pump light. This signals that, apart from the carrier spin, the VCSEL polarization is also determined by the carrier momentum     

Differential diagnosis of dysphagia in children

Dysphagia in children often presents a difficult diagnostic challenge. A systematic approach in each individual can help with diagnosis and treatment. An overview of the differential diagnosis and the diagnostic and treatment options available is provided.     

Einordnung und Terminologie des Software Reengineering

Eingegangen am 10.07.1995, in überarbeiteter Form am 01.07.1996