Optimization of Spiral MRI Using a Perceptual Difference Model

We systematically evaluated a variety of MR spiral imaging acquisition and reconstruction schemes using a computational perceptual difference model (PDM) that models the ability of humans to perceive a visual difference between a degraded “fast” MRI image with subsampling of k-space and a “gold standard” image mimicking full acquisition. Human subject experiments performed using a modified double-stimulus continuous-quality scale (DSCQS) correlated well with PDM, over a variety of images. In a smaller set of conditions, PDM scores agreed very well with human detectability measurements of image quality. Having validated the technique, PDM was used to systematically evaluate 2016 spiral image conditions (six interleave patterns, seven sampling densities, three density compensation schemes, four reconstruction methods, and four noise levels). Voronoi (VOR) with conventional regridding gave the best reconstructions. At a fixed sampling density, more interleaves gave better results. With noise present more interleaves and samples were desirable. With PDM, conditions were determined where equivalent image quality was obtained with 50% sampling in noise-free conditions. We conclude that PDM scoring provides an objective, useful tool for the assessment of fast MR image quality that can greatly aid the design of MR acquisition and signal processing strategies

Detection of spatiotemporal variation in ranavirus distribution using eDNA

Amphibian population declines have been associated with emerging diseases including ranaviruses, which can cause mass die‐offs across entire amphibian communities. Understanding and mitigating disease spread requires knowledge of spatial and temporal patterns of pathogen distribution, but also how environmental factors influence pathogen occurrence. We applied environmental DNA (eDNA) detection tools to survey spatial and temporal distributions of ranaviruses by sampling 103 waterbodies in southeastern Ontario, Canada and assessed the role of abiotic factors as predictors of pathogen occurrence. Ten waterbodies sampled during June–August (>30 km between sites) revealed that ranavirus was marginally more prevalent (p = .055) during the latter part of the summer. Ninety‐three sites sampled at a finer scale (<10 km between sites) exhibited seasonal variability in ranavirus detection (site prevalence: 56% May; 66% July). Occupancy modeling revealed that wetland size and elevation influenced ranavirus occurrence while sampling date and water temperature influenced probability of detection. These findings indicate that biotic factors, such as host density and alternative hosts, should be investigated further as likely determinants of ranavirus prevalence across the landscape. Further, these results highlight the sensitivity of eDNA for detecting widespread presence of ranavirus and that abiotic factors may have a limited role in determining its prevalence and infectivity

Emigration of hatchery‐reared Pallid Sturgeon, Scaphirhynchus albus (Forbes and Richardson), through a Missouri River dam

The middle Missouri River (MMR; Fort Randall Dam, SD to Gavins Point Dam, NE‐SD) is stocked with hatchery‐reared pallid sturgeon, Scaphirhynchus albus (Forbes and Richardson), from upper Missouri River broodstock to aid recovery of this federally endangered species. Emigration of these fish through Gavins Point Dam restores genetic connectivity that likely existed pre‐impoundment but could lead to outbreeding depression in the future. Recapture data of hatchery‐reared pallid sturgeon stocked in the MMR were evaluated to improve understanding of pallid sturgeon emigration. From 2004 to 2015, 219 emigrants were caught: 4 stocked at age ≥2 years and 215 stocked at age ≤1 year. Emigration of the 2001‐2007 year classes stocked at age 1 was a consistent phenomenon and appeared higher than emigration of year classes stocked at ages 2–3. Little evidence suggested emigration was associated with an unusually high‐water event in 2011. The annual emigration probability of individuals stocked at age 1 estimated from multi‐state mark–recapture models was 0.05 [95% confidence interval = 0.04–0.06] for fish ages ≥1 year. This study suggests that alterations to stocking practices (e.g. stocking age) may affect emigration rates and, therefore, connectivity among pallid sturgeon populations

Electrical Control of 2D Magnetism in Bilayer CrI3

The challenge of controlling magnetism using electric fields raises fundamental questions and addresses technological needs such as low-dissipation magnetic memory. The recently reported two-dimensional (2D) magnets provide a new system for studying this problem owing to their unique magnetic properties. For instance, bilayer chromium triiodide (CrI3) behaves as a layered antiferromagnet with a magnetic field-driven metamagnetic transition. Here, we demonstrate electrostatic gate control of magnetism in CrI3 bilayers, probed by magneto-optical Kerr effect (MOKE) microscopy. At fixed magnetic fields near the metamagnetic transition, we realize voltage-controlled switching between antiferromagnetic and ferromagnetic states. At zero magnetic field, we demonstrate a time-reversal pair of layered antiferromagnetic states which exhibit spin-layer locking, leading to a remarkable linear dependence of their MOKE signals on gate voltage with opposite slopes. Our results pave the way for exploring new magnetoelectric phenomena and van der Waals spintronics based on 2D materials.Comment: To appear in Nature Nanotechnolog

A Severe Case of Odontogenic Infection and Necrotizing Fasciitis of the Anterior Chest Wall and Neck.

Necrotizing fasciitis is a life-threatening infection that can be rapidly fatal. Early identification and emergent surgical management are essential to minimize morbidity and mortality. This case report describes a 25-year-old male who presented to the emergency department with a three-day history of worsening left lower dental infection and new-onset neck pain and swelling. He received broad-spectrum antibiotics and intravenous fluid resuscitation and underwent computed tomography of the neck and chest. Following intensive care unit admission, he underwent tooth extraction where intraoperative evaluation revealed subcutaneous crepitus. Immediate debridement was performed, revealing copious foul-smelling purulent discharge and necrotic tissue extending over the anterior chest wall and neck. During his hospital course, he underwent multiple debridements to manage the expanding infection. The final tissue defect was substantial, with deep dissection to muscle extending over the entire anterior surface of the rib cage to just inferior to the clavicles. This significant tissue defect was managed with skin grafts, and he was discharged home in stable condition. The patient is doing well almost a year after discharge. The key to our patient\u27s survival was the early identification and debridement of the affected tissue. Our study reinforces the tenants of wound care and aggressive management required to bolster patient odds of survival in the setting of necrotizing fasciitis and underscores the importance of maintaining vigilance in patients presenting with dental infections. This study is unique in that our patient was young, with a past medical history significant for polydrug use, and the area of debridement was substantial

Adaptative computerized cognitive training decreases mental workload during working memory precision task. A preliminary fNIRS study.

With the growing concern for the health of ageing populations, much research continues to look at the impact of cognitive training, particularly in relation to cognitive decline. We sought to use novel techniques, including augmented reality and portable neurotechnology, to evaluate the impact of a dynamically adjusting cognitive training programme, in comparison to a statically challenging alternative. Before and after an 8-week training period, and at a 5-week follow-up, we used portable functional Near Infrared Spectroscopy to examine mental workload in a mixed battery of cognitive and transfer tasks. A recently developed tablet-based task was used to identify changes in cognitive misbinding. Augmented Reality was used to create a supermarket shopping experience, as a more ecologically valid and realistic transfer task relating to an everyday task relating to independence that quickly becomes difficult with cognitive decline. The analyses showed a decreased mental workload within the dorsolateral prefrontal cortex and that participants considerably increased their performance in the trained task. Some results were maintained at the 5-week follow-up assessment. In terms of transfer, we observed reliable group differences immediately after training completion, which were mainly driven by distinct conditions. Some behavioural memory gains were maintained during the follow-up. The use of novel technologies brought new insights into the effects produced by the dynamic computerised cognitive training programme, which has potential future applications in cognitive decline screening and prevention

The future of recreational fisheries: Advances in science, monitoring, management, and practice

Recreational fisheries (RF) are complex social-ecological systems that play an important role in aquatic environments while generating significant social and economic benefits around the world. The nature of RF is diverse and rapidly evolving, including the participants, their priorities and behaviors, and the related ecological impacts and social and economic benefits. RF can lead to negative ecological impacts, particularly through overexploitation of fish populations and spread of non-native species and genotypes through stocking. Hence, careful management and monitoring of RF is essential to sustain these ecologically and socioeconomically important resources. This special issue on recreational fisheries contains diverse research, syntheses, and perspectives that highlight the advances being made in RF research, monitoring, management, and practice, which we summarize here. Co-management actions are rising, often involving diverse interest groups including government and non-government organizations; applying collaborative management practices can help balance social and economic benefits with conservation targets. Technological and methodological advances are improving the ability to monitor biological, social, and economic dynamics of RF, which underpin the ability to maximize RF benefits through management actions. To ensure RF sustainability, much research focuses on the ecological aspects of RF, as well as the development of management and angling practices that reduce negative impacts on fish populations. For example, angler behavior can be influenced to conform to conservation-minded angling practices through regulations, but is often best accomplished through growing bottom-up social change movements. Anglers can also play an important role in fisheries monitoring and conservation, including providing data on fish abundance and assemblages (i.e., citizen science). The increasing impacts that growing human populations are having on the global environment are threatening many of the natural resources and ecosystem services they provide, including valuable RF. However, with careful development of research initiatives, monitoring and management, sustainable RF can generate positive outcomes for both society and natural ecosystems and help solve allocation conflicts with commercial fisheries and conservation