We derive general expressions for the multi-tracer Fisher matrix, both assuming that cross-spectra are constrained by auto-spectra, and also allowing independent degrees of freedom in cross-spectra. show that, just like ratios power spectra, not cosmic variance. Moreover, whereas uncertainties spectra decrease with number density tracers as $\sim 1/\sqrt{\bar{n}}$, even faster, 1/\bar{n}$. simp...

UNLABELLED There has been considerable debate about the desirability of attenuation correction in whole-body PET oncology imaging. The advantages of attenuation correction are quantitative accuracy, whereas the perceived disadvantages are loss of contrast, noise amplification, and increased scanning time. In this work, we explain contrast changes between images reconstructed with and without at...

We recently introduced neurotransmitter PET (ntPET), an analysis technique that estimates the kinetics of stimulus-induced neurotransmitter (NT) release. Here, we evaluate two formulations of ntPET. The arterial (ART) approach measures the tracer input function (TIF) directly. The reference (REF) approach derives the TIF from reference region data. Arterial sampling is considered the gold stand...

There is developmental refinement of the proprioreceptive muscle afferent input to the rat ventral horn. This study explored the extent to which this occurs in the medulla. Muscle afferents were transganglionically labeled from the extensor digitorum communis forelimb muscle with cholera toxin B subunit. Tracer amounts and transport times were adjusted for animal size. Immunohistochemistry reve...

Rapid multi-tracer PET, where two to three PET tracers are rapidly scanned with staggered injections, can recover certain imaging measures for each tracer based on differences in tracer kinetics and decay. We previously showed that single-tracer imaging measures can be recovered to a certain extent from rapid dual-tracer (62)Cu - PTSM (blood flow) + (62)Cu - ATSM (hypoxia) tumor imaging. In thi...

The champagnemodel which describes the dynamical evolution of HII regions in the presence of a density discontinuity is reexamined including the effects of stellar winds. We consider stars with widely different ratios of ionizing flux to stellar wind power, as well as different distances between the star and the boundary of its parental molecular cloud. We also performed simulations with reduce...

In this presentation we overview some recent results on biased tracer diffusion in lattice gases. We consider both models in which the density of lattice gas particles is explicitly conserved and situations in which the lattice gas particles undergo continuous exchanges with a reservoir, which case is appropriate, e.g. to adsorbed monolayers in contact with the vapor phase. For all these models...

Fecal coliform bacteria are widely used as indicators of sewage contamination in surface water. However, there are some disadvantages in these microbial techniques including time consuming (18-48h) and inability in discriminating between human and animal fecal material sources. Therefore, it is necessary to seek a more specific indicator of human sanitary waste. In this study, the feasibility w...

We study the thermal Markovian diffusion of tracer particles in a 2D medium with spatially varying diffusivity D(r), mimicking recently measured, heterogeneous maps of the apparent diffusion coefficient in biological cells. For this heterogeneous diffusion process (HDP) we analyse the mean squared displacement (MSD) of the tracer particles, the time averaged MSD, the spatial probability density...

Physical activity enhances hippocampal function but its effects on neuronal structure remain relatively unexplored outside of the dentate gyrus. Using Golgi impregnation and the lipophilic tracer DiI, we show that long-term voluntary running increases the density of dendritic spines in the entorhinal cortex and hippocampus of adult rats. Exercise was associated with increased dendritic spine de...