Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

MR-Guided Kernel EM Reconstruction for Reduced Dose PET Imaging

The associated figures (and data) of the paper "MR-Guided Kernel EM Reconstruction for Reduced Dose PET Imaging" published in TRPMS

Simulation and Design Considerations of a Dual Layer Plastic Scintillator Intraoperative Probe for Radiolabeled Tumours

The design of intraoperative hand-held imaging devices that assist surgeons with the complete removal of radioac- tively labeled tumours is an important problem to solve in cancer surgery. A number of different designs for such devices have been proposed previously but they have not been completely successful in providing real-time images due to the difficulty in discrimi- nating the background from the tumour radiation. Recently, a novel approach that uses two layers of ultrathin detector foils to measure the direction of the detected positrons was proposed at Arizona University. This new concept, called a directional charged particle detector, is able to detect the direction of the detected particles by measuring the position of interaction of the positron in each detection layer. Despite having a clear working principle, there are a number of issues to be addressed in the implementation of this concept in an intraoperative probe. In this paper, we perform a simulation study to characterize and optimize a probe design that uses two thin plastic scintillators as detector layers and a silicon photomultiplier as a photo-detector. The impact of the scintillator thickness on the spatial resolution and sensitivity of the probe was evaluated using Monte Carlo simulations. Taking into account only the positron physics and a probe-tumour distance of 10 mm, the probe intrinsic spatial resolution was in the range of 3.5\u20137.5 mm. If a cover foil is added to protect the probe, the resolution is degraded to 7\u201310 mm. The tumour-gamma background discrimination was studied by sim- ulating a gamma background source coming from the patient\u2019s body, and it was found to be negligible due to the thin plastic scintillators and the use of coincidence events. The design was further evaluated including the generation and transport of the optical photons, as well as the photo-detector readout. A scintilla- tor thickness between 25 and 50 \u3bcm with a separation between the two layers of 1000 \u3bcm proved to be a good compromise regarding spatial resolution and sensitivity. With this parameter choice and without the foil cover, the intraoperative probe could reconstruct a point source with a full width at half maximum of 10 mm, that can be improved to 5 mm when reconstructing the images via iterative methods. According to this paper, the reduc- tion of the thickness of the foil cover, the introduction of new and better plastic scintillators and the current advances in silico