Undulator

The interest in vesicles as models for cell biomembranes has led to much work on the interactions within and between lipid layers. The primary contributions to vesicle stability and curvature include those familiar to us already, the electrostatic interactions between charged head groups (Chapter V) and the van der Waals interaction between layers (Chapter VI). An additional force due to thermal fluctuations in membranes produces a steric repulsion between membranes known as the Helfrich or undulation interaction. This force has been quantified by Sackmann and co-workers using reflection interference contrast microscopy to monitor vesicles weakly adhering to a solid substrate [78]. Membrane fluctuation forces may influence the interactions between proteins embedded in them [79]. Finally, in balance with these forces, bending elasticity helps determine shape transitions [80], interactions between inclusions [81], aggregation of membrane junctions [82], and unbinding of pinched membranes [83]. Specific interactions between membrane embedded receptors add an additional complication to biomembrane behavior. These have been stud-... 

A typical force curve showing the specific avidin-biotin interaction is depicted in figure Bl.20.10. The SFA revealed the strong influence of hydration forces and membrane undulation forces on the specific binding of proteins to membrane-bound receptors [81]. 

The apparatus (Fig. 82), which is constructed throughout of glass, consists of a pear-shaped bulb A (of about 5 ml. capacity) in which the solution is boiled, and which has a short length of platinum wire fused through its lowest point to assist steady boiling. The bulb A is connected near its base by a curved narrow tube B to a vertical condenser C, and from its apex by a similar tube D, undulating as shown, to the cup E. A larger outer cup F is fused to the lower neck of E as shown. 

Interference effects, which arise because of the extraordinary uniformity of thickness of the film over the spectrometer sample beam, superimposed on the absorption of incident light by parylene films, can be observed. Experimentally, a sinusoidal undulation of the baseline of the spectmm is seen, particularly in the spectral regions where there is Htde absorption by the sample. These so-called "interference fringe" excursions can amount to some... 

Because the fibers generally are anisotropic, they tend to be deposited on the wire in layers under shear. There is Htde tendency for fibers to be oriented in an out-of-plane direction, except for small undulations where one fiber crosses or passes beneath another. The layered stmcture results in the different properties measured in the thickness direction as compared to those measured in the in-plane direction. The orthotropic behavior of paper is observed in most paper properties and especially in the electrical and mechanical properties. 

Some wave phenomena, familiar to many people from the human senses, include the easy undulation of water waves from a dropped stone or the sharp shock of the sonic boom from high-speed aircraft. The great power and energy of shock events is apparent to the human observer as he stands on the rim of the Meteor Crater of Arizona. Human senses provide little insight into the transition from these directly sensed phenomena to the high-pressure, shock-compression effects in solids. This transition must come from development of the science of shock compression, based on the usual methods of scientific experimentation, theoretical modeling, and numerical simulation. 

J. Charvolin, J. F. Joanny, J. Zinn-Justin, eds. Elasticity and thermal undulations of fluid films of amphiphiles In Les Houches, Session XL VIII, 1988, Liquids at Interfaces. Amsterdam Elsevier Science, 1990. 

Mittel-meer, n. Mediterranean Sea. -meer-fieber, n. Mediterranean fever (undulant fever). 

Schwlngungs-gieichung, /. vibration equation, -kreis, m. (Elec.) oscillatory circuit, -me-thode, /. swing method. -quanten2ahl, /. vibrational quantum number, -schreiber, m. oscillograph, -weite, /. amplitude of vibra tion. -Welle,/, undulation, vibrational wave, -zahl, /. vibration nmnber, vibration fre quency. -zeit,/. time of vibration, -zustand, m. state of vibration or oscillation. 

Unding, n, absurdity nonentity, undissoziiert, a. undissociated, undulatorisc a. undulatory. unduheren, t.i. undulate, — undulierend, p.a. undulatory. 

Wallach, m. gelding Wallachian. wallen, v.t. bubble, boil up, simmer wave, heave, undulate, wiillen, v.t. boil, simmer, wallisisch, a. Welsh Valaisan,... 

The coatings produced by metal spraying have an unusual structure which is characteristic of the method of formation. They are composed of small particles usually not more than 0-01 mm in diameter which, having reached the surface in the molten condition, have splashed outwards and then solidified. Figure 12.27 (left) shows in section the irregular form of the flattened particles. In transverse section the surface profile is undulating (Fig. 12.27 (right)). 

In a practical situation, air injection can be beneficial in that, when a pipeline is shut down, it may be easier to start up again if the line is not completely full of a slurry. On the other hand, if the pipeline follows an undulating topography difficulties can arise if air collects at the high spots. 

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