Biomedical subjects

R A Pastore

Publications and source records attributed to R A Pastore.

11 recordsLinked to original sources

PubMed2001

A multi-IDT input tunable surface acoustic wave filter.

Tunable surface acoustic wave (SAW) filters (TSF) have been widely used in the wireless telecommunication systems. A prototype of a multi-IDT (interdigital transducer) input TSF has been developed. The device consists of 11 IDT paralleled in the SAW propagation path. Different SAW filter configurations are realized by selecting or combining various IDTs, resulting in the tunability of both center frequency and 3 dB bandwidth. The center frequencies of the SAW filter range from 126.8 to 199.1 MHz; the 3 dB bandwidths range from 15.2 to 58.9 MHz. Impedance weighting methods have been applied. The passband ripple has been reduced from 6.44 to 1.37 dB after resistance weighting.

Journal Article↗

PubMed2001

Theory and design of piezoelectric resonators immune to acceleration: present state of the art.

A typical low noise oscillator uses a crystal resonator as the frequency-determining element. An understanding of the fundamental nature of acceleration sensitivity in crystal oscillators resides primarily in understanding the behavior of the crystal resonator. The driving factor behind the acceleration-induced frequency shift is shown to be deformation of the resonator. The deformation drives two effects: an essentially linear change in the frequency-determining dimensions of the resonator and an essentially nonlinear effect of changing the velocity of the propagating wave. In this paper, the fundamental nature of acceleration sensitivity is reviewed and clarified, and attendant design guidance is developed for piezoelectric resonators. The basic properties of acceleration sensitivity and general design guidance are developed through the simple examples of "bulk acoustic wave (BAW) in a box" and "surface transverse wave (STW) in a box." These examples serve to clarify a number of concepts, including the role of mode shape and the basic difference between the BAW and STW cases. The design equations clarify the functional dependencies of the acceleration sensitivities on the full range of crystal resonator design and fabrication parameters.

Journal Article↗

PubMed1975

Aplastic anemia following viral hepatitis: report of two fatal cases and literature review.

Within recent years the combination of aplastic anemia following viral hepatitis has been reported with increasing frequency suggesting the existence of a causal relationship between the two conditions. Two case histories of aplastic anemia following hepatitis are presented in detail, and the information on 193 such patients reported in the literature through 1972 is summarized. A number of parameters were evaluated and extensive cross correlation carried out in order to define criteria which might have diagnostic, prognostic or therapeutic value. Males were more likely to develop bone marrow failure following hepatitis (p congruent to 0.05), but females were less likely to survive the marrow depression (p smaller than 0.025). No other statistically identifiable criteria were detected. The hematologic changes commonly encountered in hepatitis are reviewed. These and other observations support the concept that subclinical hepatitis may be responsible for a significant percentage of so-called idiopathic aplastic anemia, for which, at present, no etiology can be determined in nearly half the cases. Possible pathogenetic mechanisms are discussed as they might relate to chromosomal abnormalities which were found in one of our patients. It is suggested that occasional fortuitious human infection with animal viruses known to be both hepato- and myelotoxic could relate the hepatitis and aplasia.

Adolescent↗

PubMed1974