Response characterization of the precision open-ended coaxial probe for dielectric spectroscopy of breast tissue
ABSTRACT Large-scale dielectric spectroscopy of healthy and diseased breast tissue in the 0.1 to 20 GHz frequency range is currently underway. Open-ended coaxial probes are used as sensors to record the reflection coefficient of the tissue samples. The measured reflection coefficient is converted to the dielectric properties data through a suitable inverse technique. The collected data will aid in further advances of the microwave technology for early breast cancer detection. Thus, it is crucial to ensure the highest possible accuracy and reliability of the tissue measurements.
- SourceAvailable from: wisc.edu[show abstract] [hide abstract]
ABSTRACT: We have used open-ended coaxial probes to determine the dielectric properties of freshly excised normal and diseased breast tissue specimens. The considerable variability in size and composition of these specimens predicates the need for determining the minimum surgical specimen size that yields accurate measurements for a given probe diameter. We investigate the sensing volume of 2.2- and 3.58-mm-diameter flange-free coaxial probes for both lowand high-water-content tissue using standard liquids that exhibit dielectric properties similar to breast tissue over the microwave frequency range from 1 to 20 GHz. We also present an innovative graphical technique based on the use of Cole-Cole diagrams to determine the error thresholds in the magnitude and phase of the reflection coefficient, which bound the errors in the measured complex permittivity to an acceptable level. Results from self-consistent experiments and finite-difference time-domain simulations indicate that a tissue specimen with a thickness of 3.0 mm and a transverse dimension of 1.1 cm is the minimum size that yields accurate measurements with the 3.58-mm-diameter probe. For the 2.2-mm-diameter probe, the specimen's thickness and width should be at least 1.5 and 5 mm, respectively. These conclusions are relevant not only to breast tissue characterization, but also more generally to the dielectric characterization of a variety of low- and high-water-content biological tissues.IEEE Transactions on Microwave Theory and Techniques 05/2003; · 2.23 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: This article examines individual and group manual lateralization in nonhuman primates as a function of task's demands. It is suggested to distinguish low- from high-level manual activities with respect to the novelty variable and to the spatiotemporal scale of the movements. This review shows that low-level tasks lead to (a) symmetrical distributions of hand biases for the group and (b) manual preferences that are not indicative of the specialization of the contralateral hemisphere. In contrast, behaviors expressed in high-level tasks (a) show asymmetrical distribution of hand biases for the group and (b) seem to be related to a specialization of the contralateral hemisphere. Two types of lateralization, handedness and manual specialization, correspond to the 2 levels of tasks that are distinguished.Psychological Bulletin 02/1991; 109(1):76-89. · 15.58 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The degree of lateralization (LI) indicates both the direction and strength of a paw preference. Here, a positive value is indicative of a right paw bias, and a negative value of a left paw bias. Higher num-bers on the positive side of the scale and lower numbers on the negative side of the scale indicate a greater strength of that lateralization. The strength of motor lateralization (jLIj) is the absolute value of the LI. The use of absolute value removes directionality (i.e., does not indicate left or right paw bias) and instead in-dicates only the strength of the paw preference. Both LI and jLIj have been associated with behavioral differences in a range of species. The assessment of motor lateralization in the dog can be conducted by observing the paw used to perform motor tasks. Elevated cortisol concentrations have been associated with fearfulness in many species. Additionally, fearfulness and boldness can be assessed in response to so-called temperament tests. Consequently, in this study we examine the relationship between lateralization, temperament test results, and cortisol concen-trations in 43 potential guide dogs, of which 38 were Labrador retrievers and 5 were golden retrievers. Over a 14-month period, the current study assessed motor lateralization and salivary cortisol concen-trations 3 times (approximately 6 months of age, 14 months of age, and after the dogs' performance in the guide dog program had been determined) and behavior twice (approximately 6 and 14 months of age). This study is the first to examine the relationship between behavior, lateralization, and cortisol concen-trations in dogs. It implemented an objective and quantifiable assessment of behavior that may be of use to a variety of dog-focused stakeholders. Findings show that during the Juvenile testing period (6 months of age), dogs with higher cortisol con-centrations were typically less able to rest when exposed to the unfamiliar testing room. Results from both Juvenile and Adult Test (14 months of age) periods showed that a greater jLIj and LI were associated with more confident and relaxed behavior when dogs were exposed to novel stimuli and unfamiliar environ-ments. Significant elevations of cortisol concentrations were found at the completion of guide dog training when compared with results from the 2 prior test periods. This finding may reflect maturation or the effect of the prolonged kenneling which occurred during this period.Journal of Veterinary Behavior. 01/2009; 4:216-222.