Information content of a signal

The most basic means of conceptualizing entropy in the context of information theory is to associate the information content of a signal with a probability distribution. The amount of apparent randomness, or distribution spread, is then treated as an entropy metric and thereby associated with the information content of the system or message giving rise to the distribution. 

This chapter also deals in particular with chromatographic detection by atomic plasma spectrometry and plasma mass spectrometry (AED, MIP, ICP). With the application of such detectors, metal-specific signals can be obtained - thus the information content of a separation increases significantly. The major objectives of interfaced chromatography-atomic plasma source emission spectrometry (C-APES) are ... 

Behavioral bioassays are inextricably linked with chemical studies to decipher the information content of olfactory signals (Albone 1984). As a complement to the experimental approach described above, several research groups have applied chemical approaches, particularly gas chromatography and mass spectrometry (GC-MS),... 

This concept is one of the most difficult to quantitate. There are some relatively explicit definitions of information content for electronic communications. (For example, the Nyquist theorem defines the minimum sampling rate required in order to preserve the maximum frequency information in a periodic signal. And, the relationships between digital encoding formats and information content of a data base can be quantitated.) However, for the general problem of evaluating the results of instrumental measurements of chemical systems, the definitions for information content of data are very clear. 

The information content of a video signal can be broken down into basic component definitions consisting of (1) luminance level, (2) monochrome level, (3) chromaticity value, (4) raster coordinates, (5) point image, (6) line image, and (7) picture element. Various recording, delivery, and playback systems can be developed through the use of the following. 

Mechanoreception is the term used to describe the process that transmits the informational content of an extracellular mechanical stimulus to a receptor cell. Mechanotransduction is the term used to describe the process that transforms the mechanical stimulus content into an intra-cellular signal. The term mechanosensory is employed to mean both mechanoreception and mechanotransduction. Additional processes of inter-cellular transmission of transduced signals are required at tissue, organ and organismal structural levels. The mechanosensing process(es) of a cell enables it to sense the presence of, and to respond to, extrinsic physical loadings. This property is widespread in uni- and multicellular animals [54, 101, 53, 74, 73, 36] plants [201, 65] and bacteria [152], Tissue sensibility is a property of a connected set of cells and it is accomplished by the intracellular processes of mechanoreception and mechanotransduction. 

Roberts, J. A. and Uetz, G. W. (2005). Information content of female chemical signals in the wolf spider, Schizocosa ocreata male discrimination of reproductive state and receptivity. Anim. Behav., 70, 217-223. 

Signals from different elements cannot normally be acquired in a single NMR experiment since they require changes in spectrometer hardware. However, by using an NMR probe which is tuned to several different resonance frequencies, it is possible with modem spectrometers, to acquire signals concurrently from more than one nuclear isotope, e.g., 31P, H, and nC (Styles et al., 1979), and thus markedly increase the information content of the experiment. It is also possible to detect one or more nuclei indirectly via another nucleus (see below). 

Pedersen and Engelbrecht (1995) devised a neural network to analyze E. coli promoters. They predicted the transcriptional start point, measured the information content, and identified new features signals correlated with the start site. They accomplished these tasks by using two different encoding schemes, one with windows of 1 to 51 nucleotides, the other with a 65-nucleotide window containing a 7-nucleotide hole. An interesting idea in the study was to measure the relative information content of the input data by using the ability of the neural network to learn correctly, as evaluated by the maximum test correlation coefficient. 

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