Animals, sensors

Atema, J. Eddy chemotaxis and odor landscapes Exploration of nature with animal sensors. Biol. Bull. 191, 129-138 (1996). 

So combination systems are the most useful. There are many more stories, but a key is to use combinations not shoot-outs. Animal sensors add a component of speed, sensitivity, and cost reduction to a system. The scientific instrument in turn enhances accuracy and credibility. 

There is evidence that thermal sensors are distributed throughout the body. In animals sensors have been reported in the heart of the rabbit (6), the pulmonary vessels of sheep (7), and the spinal cord of the dog (8). However, it is agreed that some of the most important thermal receptors in the human are found in the anterior hypothalamus and the skin. The sensors at either of these locations can initiate thermoregulatory responses, and it is important that the action generated by each type of sensor be evaluated. However, most studies reported previously reflect the total response induced by both of these sources of sensory input acting together. 

Humidity sensors may be animal or plastic skins varying in length with changes in rh or lithium chloride coating changing in electrical resistance. The former is prone to lose calibration. Other comments above apply equally to rh control. 

The transport of information from sensors to the central nervous system and of instructions from the central nervous system to the various organs occurs through electric impulses transported by nerve cells (see Fig. 6.17). These cells consist of a body with star-like projections and a long fibrous tail called an axon. While in some molluscs the whole membrane is in contact with the intercellular liquid, in other animals it is covered with a multiple myeline layer which is interrupted in definite segments (nodes of Ranvier). The Na+,K+-ATPase located in the membrane maintains marked ionic concentration differences in the nerve cell and in the intercellular liquid. For example, the squid axon contains 0.05 MNa+, 0.4 mK+, 0.04-0.1 m Cl-, 0.27 m isethionate anion and 0.075 m aspartic acid anion, while the intercellular liquid contains 0.46 m Na+, 0.01 m K+ and 0.054 m Cl-. 

There are no new messengers which act as cell-membrane transmitters in plants except cytokinins calcium is more widely used than in unicellular organisms but much less so than in animals. Plants respond to light via phosphorylation and changes from dormancy requires die change of cell calcium. Response times >1 s. There are several other sensors which are sometimes described as hormones, e.g. glucose and NO. 

In practice, some anticoagulation agents such as heparin or antiplatelet agents, e.g. nitric oxide (NO) are delivered to sensor sites in order to reduce the risk of thrombus formation. Nitric oxide (NO), which is a potent inhibitor of platelet adhesion and activation as well as a promoter of wound healing in tissue, has been incorporated in various polymer metrics including PVC (poly(vinyl-chloride)), PDMS (poly-dimethyl-siloxane) and PU (poly-urethanes). Those NO release polymers have been tested in animals as outer protection coatings and have shown promising effects for the analytical response characteristics of the sensor devices [137],... 

Thioureas are most commonly prepared from reaction of isothiocyanates with amines. Also there are some reports on reactions of anime or carbodiimides with several thionating reagents. AA -Disubstituted thioureas bearing double NH groups have been developed as sensors, and as catalysts because of their hydrogen bonding ability. A,A -Disubstituted thiourea-linked sugar chains have been prepared by the reaction of isothiocyanate with amine. 

Abstract This is a short review of how neuronal sensors fit in the broader biological context of animal survival. This may help those involved in the development of engineered sensors to put in perspective their task with what the evolutionary process has achieved. Most of the information reported here is available in the educational field of neuroscience, with mention of some recent relevant findings. I have attempted to place these findings in an evolutionary perspective as it clarifies better the intrinsic role of some of the extraordinary particularities of the biological solutions of neuronal sensors. 

PXR has been demonstrated to act as an LCA sensor and plays an essential role in detoxification of cholestatic bile acids [11,61]. Studies in different animal models showed that activation of PXR protected against severe liver damage induced by LCA. Pretreatment of wild-type mice, but not the PXR-null mice, with PCN reduced the toxic effects of LCA. Moreover, genetic activation of PXR by expressing the activated... 

The exploitation of ambient fuels is attractive in situations where power needs for small electronic devices are distributed, disconnected, and long-term. This might be true for electronic sensor systems for monitoring of plant health, air quality, weather, or the presence of biohazards. In principle, the fuel can be derived from carbohydrates contained in plants or from effluent of human or animal processes. 

Calcium effects. The biochemical effects of Ca "" in the cytoplasm are mediated by special Ca -binding proteins calcium sensors"). These include the annexins, calmodulin, and troponin C in muscle (see p. 334). Calmodulin is a relatively small protein (17 kDa) that occurs in all animal cells. Binding of four Ca "" ions (light blue) converts it into a regulatory element. Via a dramatic conformational change (cf 2a and 2b), Ca -calmodulin enters into interaction with other proteins and modulates their properties. Using this mechanism, Ca "" ions regulate the activity of enzymes, ion pumps, and components of the cytoskeleton. 

The historical use of the biologically based sensors mentioned above might lead us to the conclusion that finding hidden sources of explosives simply means training some kind of animal. Indeed, that conclusion has merit, and a great deal of success has been recorded in that way. This is discussed somewhat more fully in Chapter 8. There are, of course, disadvantages to this technique. The... 

REST need not necessarily involve any animals at all. If electronic sensors of adequate sensitivity are developed, they can replace the animals. Certainly, the history of electronic instrument development shows that the earlier generations of any device are more suited for laboratory than field use, and that laboratory units can normally be expected to show better performance than portable ones. Calibration of an electronic instrument, which corresponds to training of a mammal, should become more precise and dependable than that training. 

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