C.M. Roland (December 17, 2014) Introduction Impedance spectroscopy and dielectric relaxation measurements yield the same information; however, their purpose and analysis methods differ. Impedance spectroscopy is typically used to probe electrochemical processes, while dielectric relaxation data, almost invariably expressed in the complex permittivity representation, provide information on dyna...

A quantitative theory of the middle-ear acoustics i developed and expressed interms of an electric analog. The analog network is based on the functional anatomy of the middle ear. The numerical values of its elements are derived from impedance measurements on normal and pathological ears and from anatomical data. It is shown that the input impedance of the analog agrees within the experimental ...

The problem of the rigid-piston radiator mounted in an infinite baffle has been studied widely for tutorial as well as for practical reasons. The resulting theory is commonly applied to model a loudspeaker in the audio-frequency range. A special function, the Struve function H1 (z), occurs in the expressions for the rigid-piston radiator. This Struve function is not readily available in program...

Recent studies indicated that lung tissue stress relaxation is well represented by a simple empirical equation involving a power law, t-beta (where t is time). Likewise, tissue impedance is well described by a model having a frequency-independent (constant) phase with impedance proportional to omega-alpha (where omega is angular frequency and alpha is a constant). These models provide superior ...

The permeability of the corneal endothelial layer has an important role in the correct function of the cornea. Since ionic permeability has a fundamental impact on the passive electrical properties of living tissues, here it is hypothesized that impedance methods can be employed for assessing the permeability of the endothelial layer in a minimally invasive fashion. Precisely, the main objectiv...

An important aim of nondestructive evaluation is to quantify flaws in components using sensor measurements. In pursuit of this aim, a method has been developed for finding the size and shape of planar cracks in electrical conductors from single-frequency eddy-current probe impedance measurements. In the direct problem, the change in the impedance of an eddycurrent probe due to a crack in a cond...

The most frequently used parameters to describe the barrier properties of endothelial cells (ECs) in vitro are (i) the macromolecular permeability, indicating the flux of a macromolecular tracer across the endothelium, and (ii) electrical impedance of ECs grown on gold-film electrodes reporting on the cell layer's tightness for ion flow. Due to the experimental differences between these approac...

We performed micromotion experiments using electric cell-substrate impedance sensing (ECIS) on a confluent layer of 3T3 fibroblasts exposed to different low levels of the toxin cytochalasin B. This toxin is know to affect actin polymerization and to disrupt cytoskeletal structure and function in cells, changing the morphology of confluent cell cultures and altering the nature of the cellular mi...

W hy all the mystery surrounding baluns? Here’s some straight talk to dispel the rumors! The balun — to use, or not to use — is one of today’s hottest topics in Amateur Radio. Because certain aspects of the connection between a coaxial feed line and a balanced antenna have been ignored, misunderstanding still exists concerning the function of baluns. Many commercial baluns embody some form of i...

The ability to maintain adequate gas exchange depends on the relatively homogeneous distribution of inhaled gas throughout the lung. Structural alterations associated with many respiratory diseases may significantly depress this function during tidal breathing. These alterations frequently occur in a heterogeneous manner due to complex, emergent interactions among the many constitutive elements...