Life Sciences Commons^™

Method And Apparatus For Controlling Acoustic Signal Bandwidth In An Ultrasonic Diagnostic Imaging System, Jeffrey R. Resnick, Gregory R. Bashford

Biomedical Imaging and Biosignal Analysis Laboratory

An ultrasonic imaging system includes a receive beamformer that generates analog receive signals and a scan converter. A receive signal processing path interconnects the receive beamformer and the scan converter, and this processing path included both an A/D converter characterized by a selectable sampling rate and at least one filter characterized by at least one filter parameter. The filter parameter is selected as a function of the sampling rate to provide enhanced image quality.

Method And Apparatus For Three-Dimensional Ultrasound Imaging Of Biopsy Needle, Syed Omar Ishrak, Mir Said Seyed-Bolorforosh, William Thomas Hatfield, Todd Michael Tillman, Brian Peter Geiser, Gregory R. Bashford, Michael Joseph Washburn

Biomedical Imaging and Biosignal Analysis Laboratory

A method and an apparatus for three-dimensional ultrasound imaging of a needle-like instrument, such as a biopsy needle, inserted in a human body. The instrument is visualized by transmitting ultrasound beams toward the instrument and then detecting the echo signals using a linear array of transducer elements. The problem of ultrasound being reflected from a biopsy needle in a direction away from the transducer array is solved by steering the transmitted ultrasound beams t increase the angle at which the beams impinge upon the biopsy needle. Ideally the ultrasound beams are perpendicular to the needle. This increases the system's sensitivity …

Method And Apparatus For Controlling Acoustic Signal Bandwidth In An Ultrasonic Diagnostic Imaging System, Jeffrey R. Resnick, Gregory R. Bashford

Biomedical Imaging and Biosignal Analysis Laboratory

An ultrasonic imaging system includes a receive beam former that generates analog receive signals and a scan converter. A receive signal processing path interconnects the receive beamformer and the scan converter, and this processing path includes both an A/D converter characterized by a selectable sampling rate and at least one filter characterized by at least one filter parameter. The filter parameter is selected as a function of the sampling rate to provide enhanced image quality.

Ultrasound Three- Dimensional Velocity Measurements By Feature Tracking, Gregory R. Bashford, Olaf T. Von Ramm

Biomedical Imaging and Biosignal Analysis Laboratory

This article describes a new angle-independent method suitable for three-dimensional (3-D) blood flow velocity measurement that tracks features of the ultrasonic speckle produced by a pulse echo system. In this method, a feature is identified and followed over time to detect motion. Other blood flow velocity measurement methods typically estimate velocity using one- (1-D) or two-dimensional (2-D) spatial and time information. Speckle decorrelation due to motion in the elevation dimension may hinder this estimate of the true 3-D blood flow velocity vector. Feature tracking is a 3-D method with the ability to measure the true blood velocity vector rather than …

Determining Sex Of Plains Pocket Gophers By Incisor Width, Ronald M. Case, Alan B. Sargeant

University of Nebraska State Museum: Mammalogy Papers

Biologists studying food habits of predators can often determine the prey species but not the sex of the prey from remains found at dens, in stomachs, scats, or pellets of predators. Knowledge of the sex of prey is useful in evaluating predator food habits as well as indicating sex specific differences in prey behavior.

Plains pocket gophers, Geomys bursarius, can be easily identified by the presence of two prominent grooves on the face of each upper incisor. This makes them ideal specimens for studying prey remains. In this paper, we present data that can be used to identify the …

Morphological Variation In The Southeastern Pocket Gopher, Geomys Pinetis (Mammalia: Rodentia), Stephen L. Williams, Hugh H. Genoways

University of Nebraska State Museum: Mammalogy Papers

The nominal species of southeastern pocket gophers (Geomys pinetis, G. colonus, G. cumberlandius, and G. fontanelus), which collectively occupy a geographic range on the Atlantic and Gulf coastal plain of Alabama, Georgia, and Florida, were examined for morphological variation. Univariate and multivariate analyses were used to determine age, sexual, individual, and geographic variation in G. pinetis. Significant differences were found among different age classes and between sexes. Males displayed higher individual variation than females and external measurements were more variable than cranial measurements. Of the four named species in the pinetis-species group (colonus …

Cytotypes And Morphometrics Of Two Phyllostomatid Bats, Micronycteris Hirsuta And Vampyressa Pusilla, Robert J. Baker, Hugh H. Genoways, William J. Bleier, Jerry W. Warner

University of Nebraska State Museum: Mammalogy Papers

As pointed out by Jackson (1971) and Patton (1972), the key to understanding mechanisms of chromosomal evolution lies in studies of chromosomal variation within populations that can hybridize. Hybrids between cytotypes contain the answer to problems of meiotic pairing and reduced fertility, as well as information concerning the nature of zones of contact. However, before detailed studies can be initiated, chromosomal races and hybrid zones must be located. Few chromosomal races have been described for bats (Baker, 1970a). Within the family Vespertilionidae, five species are known to have such races (Baker, 1970a) and races have been reported in two species …

Critical Flicker Frequency In A Harp Seal, Pagophilus Groenlandicus (Erxleben, 1777), Charles D. Bernholz

UNL Libraries: Faculty Publications

Critical flicker frequency (CFF) in a free-swimming harp seal (Pagophilus groenlandicus) was investigated using behavioral techniques. The resulting CFF versus intensity contour indicates a definite rod-cone break, confirming a duplex photoreceptor population whose presence had not been observed in previous morphological reports.