Intracavitary ultrasound phased arrays for prostate thermal therapies: MRI compatibility and in vivo testing

A 62 element MRI-compatible linear phased array was designed and constructed to investigate the feasibility of using transrectal ultrasound for the thermal therapeutic treatment of prostate cancer and benign prostatic hyperplasia. An aperiodic design technique developed in a previous study was used in the design of this array, which resulted in reduced grating lobe levels by using an optimized random distribution of unequally sized elements. The element sizes used in this array were selected to be favorable for both grating lobe levels as determined by array aperiodicity and array efficiency as determined by width to thickness ratios. The heating capabilities and MRI compatibility of the array were tested with in vivo rabbit thigh muscle heating experiments using MRI temperature monitoring. The array produced therapeutic temperature elevations in vivo at depths of 3-6 cm and axial locations up to 3 cm off the central axis and increased the size of the heated volume with electronic scanning of a single focus. The ability of this array to be used for ultrasound surgery was demonstrated by creating necrosed tissue lesions in vivo using short high-power sonications. The ability of the array to be used for hyperthermia was demonstrated by inducing therapeutic temperature elevations for longer exposures. Based on the acoustic and heating performance of this array, it has the potential to be clinically useful for delivering thermal therapies to the prostate and other target volumes close to body cavities.     

Hyperexpression of epidermal growth factor receptors in granulosa cells from women with polycystic ovary syndrome

We report the characterization of two distinct binding sites with receptor characteristics for leukotriene (LT)D4 and LTC4 in membranes from human lung parenchyma. The use of S-decyl-glutathione allowed us to characterize a previously unidentified high affinity binding site for LTC4. Computerized analysis of binding data revealed that each leukotriene interacts with two distinct classes of binding sites (Kd = 0.015 and 105 nM for LTC4 and 0.023 and 230 nM for LTD4) and that despite cross-reactivity, the two high affinity sites are different entities. LTD4 binding sites displayed features of G protein-coupled receptors, whereas LTC4 binding sites did not show any significant modulation by guanosine-5'-(beta, gamma-imido)triphosphate or stimulation of GTPase activity. The antagonists ICI 198,615 and SKF 104353 were unselective for the high and low affinity states of LTD4 receptor, whereas only SKF 104353 was able to recognize the two [3H]LTC4 binding sites although with different affinities. These data indicate that in human lung parenchyma, LTD4 and LTC4 recognize two different binding sites; these binding sites are different entities; and for LTD4, the two binding sites represent the interconvertible affinity states of a G protein-coupled receptor, whereas for LTC4, the high affinity site is likely to be a specific LTC4 receptor.     

Estimating Winter Streamflow Using Conceptual Streamflow Model

Ice-affected periods represent a significant portion of the annual hydrograph for most Canadian hydrometric stations. Because the stage-discharge relation is not reliable under ice-cover conditions, Water Survey of Canada subjectively interpolates winter streamflow from as few as two observations of discharge during the ice-covered season, which may last 6 months or longer. An alternative method of producing discharge estimates is proposed that uses a combination of conceptual and statistical hydrological modeling to overcome limitations in both the availability of data and our understanding of relevant processes. A conceptual hydrological model is tested to evaluate the utility of this approach for data-sparse regions. When model predictions were adjusted to fit two winter measurements, 79% of all verification measurements were within 20% of predicted estimates. There was a seasonal bias to the error distribution, with most measurements within the first 30 days after freeze-up being less than predicted and most measurements after April 1 being greater than predicted. These deviations probably result from hydraulic and hydrologic processes not represented within the model.     

Finishing conditions appropriate for recrystallization-controlled rolling of Ti-V-N-steel

Sweden where the present work was carried out     

Texture strengthening and strength differential in titanium-6Al-4V

The alloy titanium-6 Al-4 V has been processed in the laboratory to develop a wide range of textures, and determinations have been made of the yield loci for these conditions. Optical and electron metallography have been used to gain information about the operative deformation modes under various states of stress. Only limited texture strengthening is observed for conditions of tensile loading, although quite significant effects are found in compression. In strongly textured material a large strength differential occurs along thec axis direction, but this cannot be attributed to twinning. It is shown that <c +a> slip can play a major role in plastic deformation, and that the observed mechanical properties result from the peculiar characteristics of the <c +a> dislocations.     

Neural pulse frequency modulation of an exponentially correlated Gaussian process

When the input to a Neural Pulse Frequency Modulation (NPFM) system is a stationary random process the output takes the form of a train of impulses for which the occurrence times and the intensities are stationary processes of a discrete type. Particularly, the impulse occurrence times constitute a stationary point process where the average impulse frequency (average number of impulses per unit time) becomes a reciprocal of the mean impulse period. Due to the inherent nature of the modulation procedure the determination of the mean impulse period transforms to a problem of computing the mean first passage time of a random process which is not necessarily Markovian. In this paper numerical solutions of the average impulse frequency of a Neural Pulse Frequency Modulation System are obtained for the case of an exponentially correlated Gaussian input. Monte Carlo computer simulations substantiate the theoretically obtained results.