Cobwebbing

An unfortunate characteristic of early zinc polycarboxylate cements was the early development of elastomeric characteristics- cobwebbing -in the cement pastes as they aged, thus shortening working time (McLean, 1972). Improvements in cement formulation, the addition of stannous fluoride to the oxide powder (Foster Dovey, 1974, 1976) and modifications in the polyacid have eliminated this defect. However, the cements have to be mixed at quite a low powder/liquid ratio, 1 -5 1 0 by mass, when used for luting. 

When I asked if I could see Sasha s laboratory, he led me around to the back of the house, where what looked like an old wooden storage shed stood apart from the main dwelling. It may even have had a creaky door, but I m not sure. Inside, it was dimly lit and almost windowless, with cobwebs in the rafters. On numerous wooden shelves and several bench tops were an array of beakers, fractionation columns, distillation gizmos and assorted canisters and bottles. This was the lair of a mad scientist if ever there was one, I thought. 

The visual hallucinations are often composed of extremely vivid colors of geometric patterns, such as cones, spirals, or cobweb-Uke structures. Other types of hallucinations are possible. A true hallucination involves the belief by the individual that the (altered) sensations and perceptions actually represent reality. However, generally the person abusing LSD and related drugs retains the ability to test reality versus illusion and knows that the experience is not real. Thus, the... 

Recent computer simulations suggest the existence of vast filamentary networks of ionized gas, or plasma—a cosmic cobweb that now links galaxies and galaxy clusters. These warm cobwebs may be difficult to detect with current satellites. [For more information, see Glanz, J. (1998) Cosmic web captures lost matter. Science. June 26, 280(5372) 2049-50.]... 

Turning now to unintended consequences that arise because of interaction among several persons, let me begin with a famous example from economic theory, the "cobweb," also called the "hog cycle" because it was first put forward as an explanation of cyclical fluctuations in hog production. It has a much wider application, however. Fluctuations in the shipbuilding industry in recent decades had very much the same pattern, with a seller s market followed by overinvestment and glut. 

In the cobweb cycle, as drawn in Fig. X.2, the equilibrium is unstable. Any small perturbation will set up an ever-widening cycle. By the same token, if the farmers begin out of equilibrium, they will never come near it. If we draw the diagram differently, with the supply curve steeper than the demand curve, the opposite is true. After a while, the farmers converge to the equilibrium and return to it after any accidental perturbation. A preliminary conclusion might be that the realization of an equilibrium depends on details of the interaction. Some deviations from equilibrium correct themselves, while others get out of hand. 

Another line of argument is to stipulate rational expectations. In essence, this means that persons living in a society use the same models and the same information as the social scientist studying them. If he can anticipate what will happen, so can they. To achieve equilibrium, farmers do not have to go through a long sequence of cycles and learning. Using the cobweb model, they... 

There are many arguments for the rational-expectations hypothesis. In the simple cobweb cycle, and even with adaptive expectations, we must assume that each agent believes himself to be the only one to adjust rationally to the circumstances and that others act in a more or less mechanical way But this is an irrational belief, which we should not impute to people without evidence. It is surely more plausible to assume that people believe others to be as rational as themselves. Also, in a rapidly changing world people would be silly to pay much attention to the past. When oil prices quadrupled in 1973, the prices of oil before 1973 lost all relevance as guides to future prices. And if ordinary people understood much less of the economy than economists do, we would expect the latter to make much more money than they in fact do. The reason economists don t make a killing by outguessing the market is that the market has access to whatever information they have and can use it just as efficiently. ... 

This applies even when decisions are made simultaneously, if simultaneous choices have to be made on many successive occasions. The decision whether to vote in a given election might depend on the turnout in the last election. In this way, political cobweb cycles could be generated. 

Tis first a Cobweb on the Soul A Cuticle of Dust A Borer in the Axis An Elemental Rust -... 

Clearing the cobwebs from your brain, you realize that Equation 19-12 is a mass balance. 

In practice the structure of any given polymer sample is by no means as regular as the above classification would imply and in most cases defies description in terms of recognizable structural elements. For example, Wunderlich64 shows examples of cobweb structures which can be found in polymers. Clearly, for the purposes of research specific structures have been identified and studied - but this does not mean that a regular solid of macroscopic dimensions may be contracted with these structures. In polymers therefore, we always have to deal with statistical assemblies of elements more or less precisely defined as e.g. lamellar crystal, fibrous crystals, tie chains etc. 

Several other types of venomous spiders should be mentioned here. Running spiders (Chiranth-ium species) are noted for the tenacity with which they cling to the bite area, causing a sharply painful wound. The bites of cobweb spiders (Steatoda species) cause localized pain and tissue damage. Venomous jumping spiders (Phidippus species) produce a wheal (raised area) up to 5 cm across in the bite area. 

It should be noted that the appearance of the observed objects is similar, to some degree, to the carbon nanotube cobweb obtained by ablation of graphite [6]. 

Kozlov G.I. (2003) Forming of carbon cobweb at the single walls nanotube synthesis in the stream of laser ablation products widening in an electric field. Pisma v JTF, 18, 88-94. (In Russian). 

However distant from the familiarity of the American reader, the area we have entered must be viewed the way the families themselves see it. The brooding evil of Walter Scott or Robert Louis Stevenson romances, or their cheap Gothic novel imitations, gives the reader a basis for insight into the inner history of the families, and the need to begin with cobwebbed history in order to get to the bottom of Dope, Incorporated. 

The nascent powder sample has quite a different morphology compared to the solution-crystallised or melt-crystallised samples. The nascent powder morphology mainly consists of particles connected by fibrils, which is called the "cobweb" structure.26 27 The nascent powder does not have any typical lamellar morphology but has a domain structure where crystalline domains distribute within the whole powder globule (Figure 3C). The domain size has a wide range of several tens of nanometres radius. 

Nascent powder morphologies of both the nascent and etched samples observed by SEM are shown in Figure 12 for the nascent and 4- and 12-month-etched UHMW-PE powders.24 Unique "cobweb" structures, composed of globules and fibrils, are often observed on the surfaces of nascent PE powders.2 26 27 43 44 In Figure 12A, very few fibrils are observed for the nascent powder. The paste-like morphologies cover the surface of this nascent powder. The major powder structure... 

Erect your schemes with as much method and skill as you please yet if the materials be...spun out of your own entrails...the edifice will conclude at last in cobwebs... As for us the ancients, we are content with the bee to pretend to nothing of our own, beyond our wings and our voice, that is to say, our flights and our language. For the rest, whatever we have got, has been by infinite labour and search, and ranging through every corner of nature. 

Precious coral Cold Concentric rings in cobweb pattern, and longitudinal sttiations See structure Rigid Pale colours chalky-white... 

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