An integrated model of scintillator-reflector properties for advanced simulations of optical transport.

Accurately modeling the light transport in scintillation detectors is essential to design new detectors for nuclear medicine or high energy physics. Optical models implemented in software such as Geant4 and GATE suffer from important limitations that we addressed by implementing a new approach in which the crystal reflectance was computed from 3D surface measurements. The reflectance was saved in a look-up-table (LUT) then used in Monte Carlo simulation to determine the fate of optical photons.

Radiography Faculty Engaged in Online Education: Perceptions of Effectiveness, Satisfaction, and Technological Self-efficacy.

Purpose: To assess radiography faculty perceptions of the effectiveness of online courses.

Methods: An original survey instrument was created by selecting items from 3 instruments used in prior research and adding unique questions designed to elicit demographic data from faculty. The sample included a national dataset of radiography faculty members employed in Joint Review Committee on Education in Radiologic Technology-accredited programs in the United States.

Total-body imaging: Transforming the role of positron emission tomography.

The first total-body positron emission tomography (TB-PET) scanner represents a radical change for experimental medicine and diagnostic health care.

Quantitative assessment of Cerenkov luminescence for radioguided brain tumor resection surgery.

Cerenkov luminescence imaging (CLI) is a developing imaging modality that detects radiolabeled molecules via visible light emitted during the radioactive decay process. We used a Monte Carlo based computer simulation to quantitatively investigate CLI compared to direct detection of the ionizing radiation itself as an intraoperative imaging tool for assessment of brain tumor margins. Our brain tumor model consisted of a 1 mm spherical tumor remnant embedded up to 5 mm in depth below the surface of normal brain tissue.

Pair bond formation leads to a sustained increase in global cerebral glucose metabolism in monogamous male titi monkeys (Callicebus cupreus).

Social bonds, especially attachment relationships, are crucial to our health and happiness. However, what we know about the neural substrates of these bonds is almost exclusively limited to rodent models and correlational experiments in humans. Here, we used socially monogamous non-human primates, titi monkeys (Callicebus cupreus) to experimentally examine changes in regional and global cerebral glucose metabolism (GCGM) during the formation and maintenance of pair bonds.

Quantitative image reconstruction for total-body PET imaging using the 2-meter long EXPLORER scanner.

The EXPLORER project aims to build a 2 meter long total-body PET scanner, which will provide extremely high sensitivity for imaging the entire human body. It will possess a range of capabilities currently unavailable to state-of-the-art clinical PET scanners with a limited axial field-of-view. The huge number of lines-of-response (LORs) of the EXPLORER poses a challenge to the data handling and image reconstruction.

Decision-making processes shaping the home food environments of young adult women with and without children.

Although young adult women consume the majority of their total daily energy intake from home food sources, the decision-making processes that shape their home food environments have received limited attention. Further, how decision-making may be affected by the transformative experience of motherhood is unknown. In this study, we explore the factors that influence two key decision-making processes-food choices while grocery shopping and the use of non-home food sources-and whether there are differences by motherhood status.

Microbial Respiration and Formate Oxidation as Metabolic Signatures of Inflammation-Associated Dysbiosis.

Intestinal inflammation is frequently associated with an alteration of the gut microbiota, termed dysbiosis, which is characterized by a reduced abundance of obligate anaerobic bacteria and an expansion of facultative Proteobacteria such as commensal E. coli. The mechanisms enabling the outgrowth of Proteobacteria during inflammation are incompletely understood.

Screening Bioactives Reveals Nanchangmycin as a Broad Spectrum Antiviral Active against Zika Virus.

Zika virus is an emerging arthropod-borne flavivirus for which there are no vaccines or specific therapeutics. We screened a library of 2,000 bioactive compounds for their ability to block Zika virus infection in three distinct cell types with two different strains of Zika virus. Using a microscopy-based assay, we validated 38 drugs that inhibited Zika virus infection, including FDA-approved nucleoside analogs.

Attacked from All Sides: RNA Decay in Antiviral Defense.

The innate immune system has evolved a number of sensors that recognize viral RNA (vRNA) to restrict infection, yet the full spectrum of host-encoded RNA binding proteins that target these foreign RNAs is still unknown. The RNA decay machinery, which uses exonucleases to degrade aberrant RNAs largely from the 5' or 3' end, is increasingly recognized as playing an important role in antiviral defense. The 5' degradation pathway can directly target viral messenger RNA (mRNA) for degradation, as well as indirectly attenuate replication by limiting specific pools of endogenous RNAs.

Reaching 200-ps timing resolution in a time-of-flight and depth-of-interaction positron emission tomography detector using phosphor-coated crystals and high-density silicon photomultipliers.

Current research in the field of positron emission tomography (PET) focuses on improving the sensitivity of the scanner with thicker detectors, extended axial field-of-view, and time-of-flight (TOF) capability. These create the need for depth-of-interaction (DOI) encoding to correct parallax errors. We have proposed a method to encode DOI using phosphor-coated crystals.

Challenges to the Pair Bond: Neural and Hormonal Effects of Separation and Reunion in a Monogamous Primate.

Social monogamy at its most basic is a group structure in which two adults form a unit and share a territory. However, many socially monogamous pairs display attachment relationships known as pair bonds, in which there is a mutual preference for the partner and distress upon separation. The neural and hormonal basis of this response to separation from the adult pair mate is under-studied.

Collective decision-making promotes fitness loss in a fusion-fission society.

While collective decision-making is recognised as a significant contributor to fitness in social species, the opposite outcome is also logically possible. We show that collective movement decisions guided by individual bison sharing faulty information about habitat quality promoted the use of ecological traps. The frequent, but short-lived, associations of bison with different spatial knowledge led to a population-wide shift from avoidance to selection of agricultural patches over 9 years in and around Prince Albert National Park, Canada.

Improving Depth, Energy and Timing Estimation in PET Detectors with Deconvolution and Maximum Likelihood Pulse Shape Discrimination.

In a scintillation detector, the light generated in the scintillator by a gamma interaction is converted to photoelectrons by a photodetector and produces a time-dependent waveform, the shape of which depends on the scintillator properties and the photodetector response. Several depth-of-interaction (DOI) encoding strategies have been developed that manipulate the scintillator's temporal response along the crystal length and therefore require pulse shape discrimination techniques to differentiate waveform shapes. In this work, we demonstrate how maximum likelihood (ML) estimation methods can be applied to pulse shape discrimination to better estimate deposited energy, DOI and interaction time (for time-of-flight (TOF) PET) of a gamma ray in a scintillation detector.

Effects of pair bonding on dopamine D1 receptors in monogamous male titi monkeys (Callicebus cupreus).

Pair bonding leads to increases in dopamine D1 receptor (D1R) binding in the nucleus accumbens of monogamous prairie voles. In the current study, we hypothesized that there is similar up-regulation of D1R in a monogamous primate, the titi monkey (Callicebus cupreus). Receptor binding of the D1R antagonist [ C]-SCH23390 was measured in male titi monkeys using PET scans before and after pairing with a female.

Persistent neuroinflammation and cognitive impairment in a rat model of acute diisopropylfluorophosphate intoxication.

Background: Acute intoxication with organophosphorus (OP) cholinesterase inhibitors can trigger convulsions that progress to life-threatening status epilepticus. Survivors face long-term morbidity including mild-to-severe decline in memory. It is posited that neuroinflammation plays a key role in the pathogenesis of OP-induced neuropsychiatric deficits.

Bismuth germanate coupled to near ultraviolet silicon photomultipliers for time-of-flight PET.

Bismuth germanate (BGO) was a very attractive scintillator in early-generation positron emission tomography (PET) scanners. However, the major disadvantages of BGO are lower light yield and longer rise and decay time compared to currently popular scintillators such as LSO and LYSO. This results in poorer coincidence timing resolution and it has generally been assumed that BGO is not a suitable scintillator for time-of-flight (TOF) PET applications.

Habitat-mediated timing of migration in polar bears: an individual perspective.

Migration phenology is largely determined by how animals respond to seasonal changes in environmental conditions. Our perception of the relationship between migratory behavior and environmental cues can vary depending on the spatial scale at which these interactions are measured. Understanding the behavioral mechanisms behind population-scale movements requires knowledge of how individuals respond to local cues.

Activating Photodynamic Therapy in vitro with Cerenkov Radiation Generated from Yttrium-90.

The translation of photodynamic therapy (PDT) to the clinical setting has primarily been limited to easily accessible and/or superficial diseases, for which traditional light delivery can be performed noninvasively. Cerenkov radiation, as generated from medically relevant radionuclides, has been suggested as a means to deliver light to deeper tissues noninvasively to overcome this depth limitation. This article investigates the utility of Cerenkov radiation, as generated from the radionuclide yttrium-90, for activating the PDT process using clinically approved aminolevulinic acid at 1.

A conserved virus-induced cytoplasmic TRAMP-like complex recruits the exosome to target viral RNA for degradation.

RNA degradation is tightly regulated to selectively target aberrant RNAs, including viral RNA, but this regulation is incompletely understood. Through RNAi screening in Drosophila cells, we identified the 3'-to-5' RNA exosome and two components of the exosome cofactor TRAMP (Trf4/5-Air1/2-Mtr4 polyadenylation) complex, dMtr4 and dZcchc7, as antiviral against a panel of RNA viruses. We extended our studies to human orthologs and found that the exosome as well as TRAMP components hMTR4 and hZCCHC7 are antiviral.