Robert A. Pastore

Millimeter wave-induced vibrational modes in DNA as a possible alternative to animal tests to probe for carcinogenic mutations

Developing methods for alternative testing is increasingly important due to dwindling funding resources and increasing costs associated with animal testing and legislation. We propose to test the feasibility of a new and novel method for detecting DNA mutagenesis using millimeter wave spectroscopy. Although millimeter wave spectroscopy has been known since the 1950s, the cost was prohibitive and studies did not extend to large biological proteins such as DNA. Recent advances have made this technology feasible for developing laboratory and field equipment. We present preliminary findings for lesion‐induced vibrational modes in DNA observed from 80 to 1000 gigahertz (GHz). These findings suggest that there are vibrational modes that can be used as identification resonances. These modes are associated with localized defects of the DNA polymers. They are unique for each defect/lesion, and should be easy to detect. We described a field‐detecting detector based on the local modes.

Two-dimensional equations for electroelastic plates with relatively large shear deformations

A set of two-dimensional, nonlinear equations for electroelastic plates in moderately large thickness-shear deformations is obtained from the variational formulation of the three-dimensional equations of nonlinear electroelasticity by expanding the mechanical displacement vector and the electric potential into power series in the plate thickness coordinate. As an example, the equations are used to study nonlinear thickness-shear vibrations of a quartz plate driven by an electrical voltage. Nonlinear electrical current amplitude-frequency behavior near resonance is obtained. The equations and results are useful in the study and design of piezoelectric crystal resonators and the measurement of nonlinear material constants of electroelastic materials.

Fiber Bragg grating sensors for seismic wave detection

The work presented in this paper demonstrates a sensing technology for unattended seismic sensors based on the optical fiber Bragg grating. This kind of sensor can perform accurate measurements of the seismic activity due to their high sensitivity to dynamic strains caused by small ground vibrations. One of the applications is its deployment in the battlefield remote monitoring system to track and geo-locate the presence of personnel, wheeled vehicles, and tracked vehicles. The experimental data of the field test are shown as well as the comparable result with commercial seismic sensors.

Theoretical and experimental evidence for superior intrinsic Q of STW devices on rotated Y-cut quartz

Several advantages of STW devices are by now well known. These include simultaneous moderately high acoustic velocity and zero temperature coefficient of frequency, along with extremely high power handling capability. In this paper we present theoretical and experimental evidence of an additional advantage of STW devices on quasi-AT-cut quartz: the intrinsic Q of such devices is superior to that of ST-cut SAW devices and AT-cut BAW devices, with the STW having Q/spl times/f/spl ap/3.25/spl times/10/sup 13/ Hz.

Transient device modeling using the Lei‐Ting hydrodynamic balance equations

A transient semiconductor device simulation model based on the recently developed Lei‐Ting hydrodynamic balance equations is presented. Unlike other hydrodynamic models, where the various relaxation rates are imported from Monte Carlo calculations or simply assumed to be constant, our model calculates these relaxation rates within the simulation process, as functions of the electron drift velocity, electron temperature, as well as the electron density. Without any complicated mathematics, a decoupled method with a relatively large time step has been applied to the transient simulation on a one‐dimensional ballistic diode.

Stress-induced frequency shifts in langasite thickness-mode resonators

In this paper, we report on our study of stress induced effects on thickness vibrations of a langasite plate. The plate is assumed to be doubly rotated, specified by angles phi and thetas. The stresses are assumed to be uniform and planar. The first-order perturbation integral as developed by Tiersten for frequency shifts in resonators is used. The dependence of frequency shifts on phi and thetas is calculated and examined, and loci of stress-compensation are determined.

Second-order frequency shifts in crystal resonators under relatively large biasing fields

Frequency shifts in crystal resonators under relatively large biasing fields are studied from a perturbation procedure based on the equations for small fields superposed on finite biasing fields in an anisotropic elastic body. A general expression for second-order frequency shifts is obtained. Estimates are made on the order of magnitude of second-order frequency shifts in a quartz resonator due to relatively large normal acceleration.

Perturbation theory for degenerate acoustic eigenmodes

A general formulation of the perturbation procedure applied to the eigenvalue problem for resonant frequencies in crystal resonators under biasing deformations is given, with explicit treatment of the case wherein an unperturbed resonant frequency is degenerate. A rotated Y-cut quartz resonator with degenerate thickness-shear modes (b-mode/c-mode crossover point) is analyzed as an example. Results indeed show that biasing fields can cause a degenerate frequency to split into slightly different frequencies. This phenomenon may be responsible in part for the jump discontinuities in frequency temperature curves and other frequency jump phenomena.

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 multi-IDT (interdigital transducer) input TSF has been developed. The device consists of 11 IDTs 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.

Radio-propagation model based on the combined method of ray tracing and diffraction

In this paper, we consider UHF radio wave propagation in vegetated residential environments. The attenuating effects of trees as well as those due to diffraction over the buildings are investigated. A new radio wave propagation prediction model based on the combined method of ray tracing and diffraction (CMRTD) is proposed. A row of trees is modeled as a two-dimensional (2-D) cylinder. It is then represented by an equivalent phase object (EPO); a row of buildings is replaced by an absorbing screen. The position and size of the EPO as well as the amplitude and phase distributions of the input field at the EPO are determined by ray tracing. Next the scattered field is computed by the Kirchhoff diffraction theory. Among the numerical results are those of the scattering from a row of trees with circular or elliptic canopies and the scattering from a row of trees/buildings configuration. The calculations treat both plane- and cylindrical-incident waves. By comparing the results with those obtained from the exact eigenfunction expansion method, we show that the CMRTD is an accurate and efficient method to calculate the scattering from a 2-D cylinder. Moreover, the range of the validity of using the CMRTD to model the scattering from one row of trees is determined.