Over-Sensing

This is caused by the pacemaker misreading interference (i.e. muscular movement) or other parts of the cardiac cycle and assuming that they are the patient s intrinsic 

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Skeletal muscle myopotential over-sensing. Unipolar pacing systems are far more susceptible to skeletal myopotential sensing and consequent inhibition than are bipolar systems. Such inhibition represents the most common source of unipolar over-sensing (5) particularly in the atrium, because of the necessity to use high sensitivity settings. 

As with all manmade devices there is the possibility that the device can be faulty, either due to a fault in the manufacturing process or in the programming of the device. Pacemaker malfunctions can often be seen on the 12-lead ECG. The most commonly encountered problems associated with pacemaker systems include failure to sense, failure to capture, failure to pace and over sensing. 

The term resonance has also been applied in valency. The general idea of resonance in this sense is that if the valency electrons in a molecule are capable of several alternative arrangements which differ by only a small amount in energy and have no geometrical differences, then the actual arrangement will be a hybrid of these various alternatives. See mesomerism. The stabilization of such a system over the non-resonating forms is the resonance energy. 

The topic of spreading rates is of importance in the technology of the use of mono-layers for evaporation control (see Section IV-6) it is also important, in the opposite sense, in the lubrication of fine bearings, as in watches, where it is necessary that the small drop of oil remain in place and not be dissipated by spreading. Zisman and coworkers have found that spreading rates can be enhanced or reduced by the presence of small amounts of impurities in particular, strongly adsorbed surfactants can form a film over which the oil will not spread [48]. 

The ensemble density p g(p d ) of a mixing system does not approach its equilibrium limit in die pointwise sense. It is only in a coarse-grained sense that the average of p g(p,. d ) over a region i in. S approaches a limit to the equilibrium ensemble density as t —> oo for each fixed i . 

Targets and spirals have been observed in the CIMA/CDIMA system [13] and also in dilute flames (i.e. flames close to their lean flammability limits) in situations of enlianced heat loss [33]. In such systems, substantial fiiel is left unbumt. Spiral waves have also been implicated in the onset of cardiac arrhytlnnia [32] the nomial contractive events occurring across the atria in the mannnalian heart are, in some sense, equivalent to a wave pulse initiated from the sino-atrial node, which acts as a pacemaker. If this pulse becomes fragmented, perhaps by passing over a region of heart muscle tissue of lower excitability, then spiral structures (in 3D, these are scroll waves) or re-entrant waves may develop. These have the incorrect... 

The set of eigenveetors of any Hermitian matrix form a eomplete set over the spaee they span in the sense that the sum of the projeetion matriees eonstrueted from these eigenveetors gives an exaet representation of the identity matrix. 

Many human diseases are caused when certain proteins are either over- or underexpressed. Eor example, breast cancer can be induced by overexpressing certain cellular oncogenes within mammary tissue. To study the disease, researchers produce a line of transgenic mice that synthesize an abnormal amount of the same protein. This leads to symptoms of the disease in mice that are similar to what is found in humans. A protein can be overexpressed by inserting a DNA constmct with a strong promotor. Conversely, underexpression of a protein can be achieved by inserting a DNA constmct that makes antisense RNA. This latter blocks protein synthesis because the antisense RNA binds and inactivates the sense mRNA that codes for the protein. Once a line of mice is developed, treatments are studied in mice before these therapies are appHed to humans. 

In 1986, the National Geographic Society, in cooperation with the MoneU Center, conducted a worldwide survey of the sense of smell. Over 10 million survey forms were sent to readers of the Society s journal, of which close to 1.5 million forms were completed and returned. With responses to 40 demographic and 42 odor-related questions, the results constitute the largest set of data on human olfaction (4). 

For reasons that are not fiiUy understood, PPSF exhibits generally improved compatibiUty characteristics over either PSF or PES in a number of systems. An example of this is blends of PPSF with polyaryletherketones (39,40). These blends form extremely finely dispersed systems with synergistic strength, impact, and environmental stress cracking resistance properties. Blends of PPSF with either PSF or PES are synergistic in the sense that they exhibit the super-toughness characteristic of PPSF at PSF or PES contents of up to 35 wt % (33,34). The miscibility of PPSF with a special class of polyimides has been discovered and documented (41). The miscibility profile of PPSF with high temperature (T > 230° C) polysulfones has been reported (42). 

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