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Background/Aims: Ultrasound elasticity imaging visually represents tissue hardness measurements using high-resolution ultrasound speckle-tracking algorithms. This method has recently been applied in the renal setting to measure arterial compliance in end-stage renal disease (ESRD) and the mechanical properties of transplant kidneys in vivo. Methods: Ultrasound radio-frequency signal measurements were made of the brachial artery in 5 ESRD subjects and 5 healthy controls and renal transplant measurements in 2 subjects, 1 with chronic allograft nephropathy (CAN) and 1 with normal graft function. Results: Maximal brachial artery percent strain measurements for healthy controls were 32.9 ± 10.2% (mean ± SD) and for ESRD subjects maximal percent strains were 4.9 ± 1.8%. Transplant renal cortical strain for the subject with CAN was approximately one third that of the healthy transplant recipient. Conclusion: Ultrasound elasticity imaging offers the potential to noninvasively measure the mechanical properties of structures within the body.

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Aims:  To develop a real‐time PCR method for rapid differential identification of many clinically important mycobacteria to the species level. Methods and Results:  Eighteen Mycobacterium species that are considered clinically important were targeted for the identification. One primer pair and 21 pairs of hybridization probes (HybProbes) specific for the genus, species or complex were designed based on the rpoB gene sequences of mycobacteria. Twenty‐five different Mycobacterium reference species were tested. In a single round of real‐time PCR, all the nontuberculous mycobacteria (NTM) species tested were identified at the genus level and 16 of the 18 targeted species were differentially identified to the species or complex level during the amplification cycles; subsequent melting curve analysis allowed the specific identification of all the target species at the species or complex level without cross‐reactivity with the other species. Conclusions:  The developed real‐time PCR assay rapidly identifies the NTM at the genus level and 18 clinically important Mycobacterium species at the species or complex level. Significance and Impact of the Study:  This real‐time PCR assay provides a useful tool for the rapid differentiation of most clinically important Mycobacterium species.

We report an optical probe based on a single double-clad fiber (DCF), which is suitable for fluorescence spectroscopy. The excitation light is delivered through the small diameter core of the DCF and the excited fluorescence light is collected by the large diameter inner cladding of the same fiber. To retrieve the signal beam from the inner cladding, we utilize a DCF coupler that couples only the light beams in the inner claddings of two different pieces of DCF. It was found that the separation of the channel for the excited beam from the channel for the excitation beam in the same piece of fiber could diminish the autofluorescence background noise generated by the fiber itself, while maintaining all the benefits of a single-fiber probe system. The usefulness of the DCF probe and the performance of the DCF coupler are then reported by presenting the fluorescence spectrum of a fresh gingko leaf and comparing it with the spectrum taken with conventional methods. The fabrication process of the DCF fiber and the inner cladding mode coupler for it are also presented.

The detectability and discriminability of virtual haptic gratings were analyzed in the frequency domain. Detection (Exp. 1) and discrimination (Exp. 2) thresholds for virtual haptic gratings were estimated using a force-feedback device that simulated sinusoidal and square-wave gratings with spatial periods from 0.2 to 38.4 mm. The detection threshold results indicated that for spatial periods up to 6.4 mm (i.e., spatial frequencies >0.156 cycle/mm), the detectability of square-wave gratings could be predicted quantitatively from the detection thresholds of their corresponding fundamental components. The discrimination experiment confirmed that at higher spatial frequencies, the square-wave gratings were initially indistinguishable from the corresponding fundamental components until the third harmonics were detectable. At lower spatial frequencies, the third harmonic components of square-wave gratings had lower detection thresholds than the corresponding fundamental components. Therefore, the square-wave gratings were detectable as soon as the third harmonic components were detectable. Results from a third experiment where gratings consisting of two superimposed sinusoidal components were compared (Exp. 3) showed that people were insensitive to the relative phase between the two components. Our results have important implications for engineering applications, where complex haptic signals are transmitted at high update rates over networks with limited bandwidths.