Modulation Transfer Function prediction

The maximum entropy method was one of several techniques that were used to restore the Hubble images. However, all techniques were hampered by lack of complete knowledge of the point-spread function. Using a point-spread function that included errors (either because of noise in a measured point-spread function, or modeling imperfections in predicted point-spread function) further adds to the ill-posed nature of the restoration problem. Although the modulation transfer function tended not to be zero-valued (at least not as severely as in the radio interferometry case described below), this was of only small comfort when imaging weak objects, as the... 

Unlike the diode laser, the transfer function of many modulators is easily expressible in a simple analytical form. For example, the Mach-Zehnder transfer function is a simple raised cosine, 1 + cosrp, as shown by the solid curve in Fig. 9.55. Consequently, the linearity is a predictable function of the chosen bias point. For example, operating a Mach-Zehnder at /2 forces aU of the even-order distortion terms to zero. Using this bias point in a broad-band application means that the IM-free DR is determined by the odd-order distortion, which is dominated by the third-order term. Recall that for narrow-band systems the second-order distortion terms fall outside the pass band and consequently can be filtered out. Thus, for such applications the bias point can be moved away from /2 with no system consequence. One reason... 

CNTs and other nano-sized carbon structures are promising materials for bioapplications, which was predicted even previous to their discovery. These nanoparticles have been applied in bioimaging and drag delivery, as implant materials and scaffolds for tissue growth, to modulate neuronal development and for lipid bilayer membranes. Considerable research has been done in the field of biosensors. Novel optical properties of CNTs have made them potential quantum dot sensors, as well as light emitters. Electrical conductance of CNTs has been exploited for field transistor based biosensors. CNTs and other nano-sized carbon structures are considered third generation amperometric biosensors, where direct electron transfer between the enzyme active center and the transducer takes place. Nanoparticle functionalization is required to achieve their full potential in many fields, including bio-applications. 

Transfer rates of molecules across the skin can be modelled using basic kinetic equations and appropriate solutions to Fick s Laws of diffusion. They have been applied to elucidate the mechanism by which molecules cross the skin and how the barrier function may be modulated. It is possible to absorb formulation components into the outer layers of the skin such that they enhance or retard penetration [32]. Even though considerable effort has been given to understanding these mechanisms of action, the precise route has still not been unequivocally identified. Part of the problem is the inherent variability of the skin. Despite this, predictive models have been obtained that have considerable utility in risk assessment and in the development of topical and transdermal medicines and their formulations. 

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