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The quality of reconstructed dynamic PET images, as well as the statistical reliability of the estimated pharmacokinetic parameters is often compromised by high levels of statistical noise, particularly at the voxel level. Many denoising strategies have been proposed, both in the temporal and spatial domain, which substantially improve the signal to noise ratio of the reconstructed dynamic images. However, although most filtering approaches are fairly successful in reducing the spatio-temporal inter-voxel variability, they may also average out or completely eradicate the critically important temporal signature of a transient neurotransmitter activation response that may be present in a non-steady state dynamic PET study. In this work, we explore an approach towards temporal denoising of non-steady state dynamic PET images using an artificial neural network, which was trained to identify the temporal profile of a time-activity curve, while preserving any potential activation response. We evaluated the performance of a feed-forward perceptron neural network to improve the signal to noise ratio of dynamic [11C]raclopride activation studies and compared it with the widely used highly constrained back projection (HYPR) filter. Results on both simulated Geant4 Application for Tomographic Emission data of a realistic rat brain phantom and experimental animal data of a freely moving animal study showed that the proposed neural network can efficiently improve the noise characteristics of dynamic data in the temporal domain, while it can lead to a more reliable estimation of voxel-wise activation response in target region. In addition, improvements in signal-to-noise ratio achieved by denoising the dynamic data using the proposed neural network led to improved accuracy and precision of the estimated model parameters of the lp-ntPET model, compared to the HYPR filter. The performance of the proposed denoising approach strongly depends on the amount of noise in the dynamic PET data, with higher noise leading to substantially higher variability in the estimated parameters of the activation response. Overall, the feed-forward network led to a similar performance as the HYPR filter in terms of spatial denoising, but led to notable improvements in terms of temporal denoising, which in turn improved the estimation activation parameters. [ABSTRACT FROM AUTHOR]

An experimental study of the absorption spectra of four types of diesel fuel is presented where prolonged boiling simulates the ageing process of fuels. Explicit expressions are derived for diesel fuel droplets in various realistic droplet radii and external gas temperature ranges for all four types of fuel.

Background Standardized training and clinical protocols using biofeedback for the treatment of fecal incontinence ( FI) are important for clinical care. Our primary aims were to develop, implement, and evaluate adherence to a standardized protocol for manometric biofeedback to treat FI. Methods In a Pelvic Floor Disorders Network ( PFDN) trial, participants were enrolled from eight PFDN clinical centers across the United States. A team of clinical and equipment experts developed biofeedback software on a novel tablet computer platform for conducting standardized anorectal manometry with separate manometric biofeedback protocols for improving anorectal muscle strength, sensation, and urge resistance. The training protocol also included education on bowel function, anal sphincter exercises, and bowel diary monitoring. Study interventionists completed online training prior to attending a centralized, standardized certification course. For the certification, expert trainers assessed the ability of the interventionists to perform the protocol components for a paid volunteer who acted as a standardized patient. Postcertification, the trainers audited interventionists during trial implementation to improve protocol adherence. Key Results Twenty-four interventionists attended the in-person training and certification, including 46% advanced practice registered nurses (11/24), 50% (12/24) physical therapists, and 4% physician assistants (1/24). Trainers performed audio audits for 88% (21/24), representing 84 audited visits. All certified interventionists met or exceeded the prespecified 80% pass rate for the audit process, with an average passing rate of 93%. Conclusions & Inferences A biofeedback protocol can be successfully imparted to experienced pelvic floor health care providers from various disciplines. Our process promoted high adherence to a standard protocol and is applicable to many clinical settings. [ABSTRACT FROM AUTHOR]

Focuses on a study that confirmed the higher reactivity and density of thermodynamically non-equilibrium high-temperature plasmas than that of glow-discharge plasmas. Benefits from high-frequency electric discharges; Aspect categorized as a thermodynamically non-equilibrium high temperature plasma; Increase in the concentration of atomic oxygen with power.

Objective: To compare the dose-optimisation potential of a smoothing filtered backprojection (FBP) and a hybrid FBP/iterative algorithm to that of a standard FBP algorithm at three slice thicknesses for hepatic lesion detection with multidetector CT. Methods: A liver phantom containing a 9.5-mm opacity with a density of 10 HU below background was scanned at 125, 100, 75, 50 and 25 mAs. Data were reconstructed with standard FBP (B), smoothing FBP (A) and hybrid FBP/iterative (iDose4) algorithms at 5-, 3- and 1-mm collimation. 10 observers marked opacities using a four-point confidence scale. Jackknife alternative free-response receiver operating characteristic figure of merit (FOM), sensitivity and noise were calculated. Results: Compared with the 125-mAs/5-mm setting for each algorithm, significant reductions in FOM (p<0.05) and sensitivity (p<0.05) were found for all three algorithms for all exposures at 1-mm thickness and for all slice thicknesses at 25 mAs, with the exception of the 25-mAs/5-mm setting for the B algorithm. Sensitivity was also significantly reduced for all exposures at 3-mm thickness for the A algorithm (p<0.05). Noise for the A and iDose4 algorithms was approximately 13% and 21% lower, respectively, than for the B algorithm. Conclusion: Superior performance for hepatic lesion detection was not shown with either a smoothing FBP algorithm or a hybrid FBP/iterative algorithm compared with a standard FBP technique, even though noise reduction with thinner slices was demonstrated with the alternative approaches. Advances in knowledge: Reductions in image not necessarily translate to an improvement noise with non-standard CT algorithms do in low-contrast object detection. [ABSTRACT FROM AUTHOR]

Three sets of activated carbons (ACs) were prepared with the same precursor but activated differently (by CO or water vapour) with various burn-off levels. The ACs demonstrate increased deviation of the pore shape from the slitshaped model with increasing burn-off and contributions of pores of different sizes depending on the activation type. Significant re-arrangement of adsorption complexes, especially of the Van der Waals type characteristic for nonpolar or weakly polar adsorbates (H, CH, CHCl, CHCl), occurs in both micropores and mesopores of ACs with decreasing temperature. The behaviour of their mixtures with water and DMSO can strongly differ from that of individual adsorbates. [ABSTRACT FROM AUTHOR]