In modern PET scanners, image reconstruction is performed sequentially in two steps regardless of the reconstruction method: 1. Attenuation correction factor computation (ACF) from transmission scans, 2. Emission image reconstruction using the computed ACFs. This reconstruction scheme does not use all the information in the transmission and emission scans. Post-injection transmission scans cont...

The analysis of the ultrasonic frequency-dependent backscatter coefficient of aggregating red blood cells reveals information about blood structural properties. The difficulty in applying this technique in vivo is due to the frequency-dependent attenuation caused by intervening tissue layers that distorts the spectral content of backscattering properties from blood microstructures. An optimizat...

We used the x-ray extended-range technique to measure the x-ray mass attenuation coefficients of silicon with an accuracy between 0.27% and 0.5% in the 5 keV220 keV energy range. Subtraction of the x-ray scattering contribution enabled us to derive the corresponding x-ray photoelectric absorption coefficients and determine the absolute value of the imaginary part of the atomic form factor of si...

We demonstrate the utility of using the equivalent bottom roughness for calculating the friction factor and the drag coefficient of a seagrass meadow for conditions in which the meadow height is small compared to the water depth. Wave attenuation induced by the seagrass Posidonia oceanica is evaluated using field data from bottom-mounted acoustic doppler veloci meters (ADVs). Using the data fro...

The DNA binding specificities of CREB1 and CREB2 homodimers and the CREB2/cJun heterodimer were analyzed with a CASTing technique. All but one of the selected sequences varied from the consensus CRE (TGACGTCA) by three nucleotides or less. The profile of variations selected and the binding affinity for these sequences were unique for each CREB complex. The affinities were not effected by the pa...

Without incorporation of weak-shock theory, the lossless Burgers equation predicts a multivalued waveform for nonlinear propagation beyond a certain distance. Inclusion of thermoviscous attenuation, which increases quadratically with frequency, prevents the occurrence of multivalued waveforms. The same is true for any attenuation law that is proportional to frequency raised to an exponent great...

we propose and demonstrate a bandpass microwave photonic filter (MPF) with ultrahigh stopband attenuation and skirt selectivity based on a simple signal cancellation technique. By injecting two phase modulated signals located on opposite sides of two resonant gain peaks of a Fabry-Pérot semiconductor optical amplifier (FP-SOA), two microwave frequency responses can be generated by the two input...

Waveform light detection and ranging (wLiDAR) records the entire backscattered signal of an emitted laser pulse, enabling deeper penetration through tree canopy. However, due to interactions (e.g. reflection, absorption, and transmission) within the canopy, the full proportion of emitted light may not reach the ground, resulting in an attenuated waveform. Correction of attenuation will result i...

Dual energy CT has the ability to give more information about the test object by reconstructing the attenuation factors under different energies. These images under different energies share identical structures but different attenuation factors. By referring to the fully sampled low-energy image, we show that it is possible to greatly reduce the sampling rate of the high-energy image in order t...

in this study, analysis is presented in two steps. in the first step, the theoretical s-wave displacement spectra, conditioned by frequency-independent q, was fitted with the observed displacement spectra. therefore corner frequency, moment magnitude and frequency-independent q for each record were estimated simultaneously and the estimate of error is given in the root-mean-square sense over al...