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Several of the CPK colors refer mnemonically to colors of the pure elements or notable compound. For example, hydrogen is a colorless gas, carbon as charcoal, graphite or coke is black, sulfur powder is yellow, chlorine is a greenish gas, bromine is a dark red liquid, iodine in ether is violet, amorphous phosphorus is red, rust is dark orange-red, etc.
These early models also established the CPK coloring scheme that is still used today to differentiate the different types of atoms in molecular models (e.g. carbon = black, oxygen = red, nitrogen = blue, etc). This early model was improved upon in 1966 by W.L. Koltun and are now known as Corey-Pauling-Koltun (CPK) models. [5]
A Nicholson model, showing a short part of protein backbone (white) with side chains (grey). Note the snipped stubs representing hydrogen atoms. A good example of composite models is the Nicholson approach, widely used from the late 1970s for building models of biological macromolecules.
Many models of communication include the idea that a sender encodes a message and uses a channel to transmit it to a receiver. Noise may distort the message along the way. The receiver then decodes the message and gives some form of feedback. [1] Models of communication simplify or represent the process of communication.
A model of communication is a simplified presentation that aims to give a basic explanation of the process by highlighting its most fundamental characteristics and components. [16] [8] [17] For example, James Watson and Anne Hill see Lasswell's model as a mere questioning device and not as a full model of communication. [10]
The emission spectrum characteristics of some elements are plainly visible to the naked eye when these elements are heated. For example, when platinum wire is dipped into a sodium nitrate solution and then inserted into a flame, the sodium atoms emit an amber yellow color. Similarly, when indium is inserted into a flame, the flame becomes blue.
Color printing is a binary system, where ink is either present or not present, so all color separations to be printed must be translated into dots at some stage of the work-flow. Traditional line screens which are amplitude modulated had problems with moiré but were used until stochastic screening became available.
The Shannon–Weaver model is one of the earliest models of communication. [2] [3] [4] It was initially published by Claude Shannon in his 1948 paper "A Mathematical Theory of Communication". [5] The model was further developed together with Warren Weaver in their co-authored 1949 book The Mathematical Theory of Communication.