A very high frequency radio interferometer for investigating ionospheric disturbances using geostationary satellites. Determination of changes in exospheric electron content by a comparison of group delay and Faraday rotation

The theory and development of a VHF correlation radio interferometer for investigating ionospheric disturbances are discussed. The system was developed to receive signals from the geostationary Applications Technology Satellites. Amplitude and phase variations of the signal passing through the ionosphere can be detected by this instrument. The system consists of two superheterodyne receivers separated by a distance known as the baseline of the system. Since the system is a phase sensitive instrument, the local oscillators of the two receivers must be phase coherent. This is accomplished by using phase-locked loops for generating the local oscillators. The two signals from the separate receivers are cross-correlated by multiplying the two signals together and then time averaging the result. The sensitivity of the instrument is increased by off-setting one of the local oscillators by a small amount

Backscatter Inversion in Spherically Asymmetric Ionosphere

It is Well Known that Various Diurnal and Morphological Features of the Ionosphere Reveal Substantial Departures from the Normally Simplified Assumption of Spherical Symmetry at Certain Times of the Day or at Certain Geographic Locations. a Radio Ray Passing through Such an Ionosphere Must Bear Information About its Horizontal Gradients. the Leading Edge of a Backscatter Ionogram is Formed by Obliquely Propagated Radio Rays of Minimum Time Delay and Hence is Useful in Deducing Information About the Ionospheric Horizontal Gradients. in This Regard, the Ionospheric Electron Density Distribution is Modeled by a Locally Quasi‐parabolic Layer with Six Parameters. This Six‐parameter Space is Known as the \u27ion state.\u27 Our Object is to Seek the \u27best\u27 Ion state in the Sense that the Corresponding Mean Square Error in Group Delay is a Minimum. a Computer Program Has Been Written to Carry Out the Specified Procedure. a Number of Sample Calculations Are Presented and Discussed. Copyright 1979 by the American Geophysical Union

Modeling of Dielectric Mixtures Containing Conducting Inclusions with Statistically Distributed Aspect Ratio

An analytical model of composites made of a dielectric base and randomly oriented metal inclusions in the form of nanorods is presented. This model is based on the generalized Maxwell Garnett (MG) mixing rule. In this model, the nanorod particles are modeled as prolate spheroids with a statistically normal distribution of their aspect ratios. It is shown that parameters of the distribution laws affect the frequency characteristics of the composites both at microwave and optical frequencies. The results of computations are represented

Expert System Algorithms for Identifying Radiated Emission Problems in Printed Circuit Boards

Radiated emission algorithms for a printed circuit board EMC expert system are described. The expert system mimics the thinking processes that human EMC engineers would use to analyze circuit boards and make design recommendations. Working with limited information about the enclosure, cables or the exact nature of the signals, the expert system evaluates different structures on the printed circuit board looking for potentially strong radiated emission sources. Results obtained from the analysis of a sample printed circuit board are provided to demonstrate how the expert system quickly identifies problems that would otherwise be difficult to locate

A Circuit Approach to Model Narrow Slot Structures in a Power Bus

A coupled transmission line model for narrow slot structures in DC power planes is proposed. This approach, combined with SPICE-based cavity models and a segmentation method, provides an easy and fast way to model relatively complex structures of power planes with narrow slots often used for isolation purposes. This approach is used to achieve isolation using gapping. The cavity model formulations for rectangular and isosceles right triangular segments are reviewed. The rationale of modeling the narrow slot as a three-conductor transmission line is described. The modeling results are shown and compared with the output of a full wave simulation tool, HFSS, and with experimental measurements

Taste function in early stage treated and untreated Parkinson’s disease

Since brain stem regions associated with early Parkinson’s disease (PD) pathology encroach upon those involved in taste function, the ability to taste may be compromised in PD. However, studies on this point have been contradictory. We administered well-validated wholemouth and regional taste tests that incorporated multiple concentrations of sucrose, citric acid, caffeine, and sodium chloride to 29 early stage PD patients and 29 age-, sex-, and race-matched controls. Electrogustometry was also performed on the anterior tongue. The PD cohort was tested both on and off dopamine-related medications in counterbalanced test sessions. While whole-mouth taste identification test scores for all stimuli were, on average, nominally lower for the PD patients than for the controls, a trend in the opposite direction was noted for the intensity ratings at the lower stimulus concentrations for all stimuli except caffeine. Moreover, regional testing found that PD subjects tended to rate the stimuli, relative to the controls, as more intense on the anterior tongue and less intense on the posterior tongue. No significant associations were evident between taste test scores and UPDRS scores, L-DOPA medication equivalency values, or [99mTc]TRODAT-1 SPECT imaging of dopamine transporter uptake within the striatum and associated regions. Our findings suggest that suprathreshold measures of taste function are influenced by PD and that this disease differentially influences taste function on anterior (CN VII) and posterior (CN IX) tongue regions. Conceivably PD-related damage to CN IX releases central inhibition on CN VII at the level of the brainstem, resulting in enhanced taste intensity on the anterior tongue

Validation of Equivalent Circuits Extracted from S-Parameter Data for Eye-pattern Evaluation

S-parameter circuit model extraction is usually characterized by a trade off between accuracy and complexity. Trading one feature for another may or may not affect the goodness of the reconstructed S-parameter data, which are obtained from frequency domain simulations of the models extracted. However, the ultimate test for the validity of these equivalent circuit representations should be left to eye-diagram simulations, which provide useful insights, from an SI point of view, about the degradation of the signal, as it travels through the system. Physics based simplication procedures can be used to tune the models and achieve less complexity, whereas the comparisons of the eye-diagrams may help to quantify the goodness of an these circuits extracted. In fact, the most accurate model is not necessary the best to be used

Pharmacogenetic studies on the drug-related lupus syndrome. differences in antinuclear antibody development and drug-induced DNA damage in rapid and slow acetylator animal models

Pharmacogenetic study of an inbred mouse model system derived from A/J (slow acetylator) and C57BL/6J (rapid acetylator) parental strains shows that spontaneous occurrence of antinuclear antibodies is associated with the slow acetylator phenotype although the development of spontaneous and procainamide-induced antinuclear antibodies is a dissociable process. In another study using primary cultures of intact hepatocytes obtained from slow and rapid acetylator rabbits, observations indicate that the amount of DNA damage induced by exposure to hydrazine and arylamine containing foreign compounds depends on the concentration of the foreign compound used as well as on the acetylator phenotype. Exposure to hydralazine induced greater DNA damage in slow acetylator hepatocytes whereas exposure to the arylamine carcinogen, 2-aminofluorene, induced greater DNA damage in rapid acetylator hepatocytes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37756/1/1780240801_ftp.pd

Axonal Dynamics of Excitatory and Inhibitory Neurons in Somatosensory Cortex

Electrophysiology-delivery of fluorescent viral vectors-and two-photon microscopy were used to demonstrate the rapidity of axonal restructuring of both excitatory and inhibitory neurons in rodent cortical layer II/III following alterations in sensory experience