Artifacts In Magnetic Resonance Imaging and Computed Tomography Caused By Dental Materials

BACKGROUND: Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images. METHODS: Test samples of 44 materials (Metal and Non-Metal) commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software. RESULTS: In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact. SIGNIFICANCE: Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images

Tracking cycles of Phanerozoic opening and closing of ocean basins using detrital rutile and zircon geochronology and geochemistry

Sedimentary basins provide a deep time archive of tectonic and Earth-surface processes that can be leveraged by detrital mineral U-Pb dating and geochemistry to track paleogeography, magmatism, and crustal evolution. Zircon preserves the long-term (billions of years) record of supercontinent cycles; however, it is biased toward preserving felsic crustal records. Detrital rutile complements the detrital zircon record by providing constraints on the time and temperature of rifting and mafic magmatism, metamorphism, exhumation of the middle and lower crust, subduction, and amagmatic orogenesis. We use detrital zircon U-Pb and detrital rutile U-Pb geochronology and trace element analysis of Permian to Eocene siliciclastic rocks in the southern Pyrenees to capture supercontinent cycles of ocean basins opening and closing. Detrital rutile age spectra show peaks at ca. 100 Ma associated with rifting and hyperextension in the Pyrenean realm, 200 Ma associated with the Central Atlantic Magmatic Province, and 330 Ma, 375 Ma, and 400 Ma associated with subduction and Rheic Ocean crust formation. Zr-in-rutile thermometry and rutile Cr-Nb systematics provide further insight into metamorphic facies (peak metamorphic temperatures) and source rock lithology (mafic versus felsic affinity). Detrital zircon age spectra have peaks at ca. 300 Ma, 450 Ma, and 600 Ma associated with major orogenic events and felsic magmatism, and Th/U ratios provide information on relative zircon formation temperatures. Comparison of these independent records shows that detrital rutile reflects rifting, magma-poor orogenesis, and oceanic lithospheric processes, while detrital zircon detects continental lithospheric processes. Integrated detrital zircon and rutile data sets archive past geological events across multiple Wilson cycles

Integration of a Medical Voice Program in the Performing Community: Establishing an Extended Voice Team Network

This article will summarize the process of establishing and growing relationships with professional voice users and vocal organizations in the community, including educational institutions, large- and small-scale performing arts organizations, professional associations, individual professional voice users and teachers, and others. We will present a review of the literature and recommendations regarding integration of a voice program into the professional voice community. This will include identification of appropriate organizations and individuals for the extended voice network, methods of outreach, cultivation of relationships, and difficulties encountered. The idea of multidisciplinary treatment of voice disorders through a voice team has been well-established in the literature. Although many voice teams are further integrating themselves into their local communities, there has been little written about this. We hope that by sharing our process, we may provide information to others and learn more ourselves about how to better serve our professional voice communities

Provenance Analysis of the Andrée Land Basin and Implications for the Paleogeography of Svalbard in the Devonian

During the Devonian, the Svalbard Archipelago lay at low latitudes, occupying a paleogeographic position at the intersection of Caledonian and Ellesmerian orogens. Provenance analysis, including detrital zircon U-Pb age studies, of Devonian (ca. 420–360 Ma) strata from the Andrée Land Basin, Svalbard, help reconstruct sediment sources to understand the assembly of the three basement provinces that make up Svalbard, which are presently separated by Devonian sedimentary basins and(or) faults with syn-to post-Devonian displacement. The studied Andrée Land Group strata, which are part of the North Atlantic's Old Red Sandstone, consist of the Early Devonian Wood Bay Formation and Middle to Late Devonian Mimerdalen subgroup. Paleocurrent indicators from Lower to lower-Middle Devonian strata record north-directed sediment transport. Detrital zircon U-Pb ages indicate a prominent “Caledonian” signal and include sources from Svalbard's Northwestern and(or) Southwestern basement provinces. In Middle and Upper Devonian strata, paleocurrents and detrital zircon ages record a shift to a predominantly eastern-northeastern provenance, likely from the uplifting Ny-Friesland block along the Billefjorden Fault Zone. Late Ediacaran-early Cambrian detrital zircons in the uppermost Planteryggen Formation (Frasnian) indicate extrabasinal sources possibly associated with the Timanian orogen of Northern Baltica. The combined provenance data suggest Svalbard may have already been assembled, similar to the modern block, with the Andrée Land Basin located between modern exposures of the Southwestern/Northwestern and the Northeastern basement provinces. Comparison of detrital zircon ages from Andrée Land Group strata with those from other circum Arctic Devonian strata provides constraints on Svalbard's paleogeographic position in the Devonian

Zika outbreak of 2016: insights from twitter

An outbreak of the Zika virus in 2016 caused great concern among the general public and generated a burst of tweets. The aim of this study was to develop a better understanding of the types of discussions taking place. Tweets were retrieved from the peak of the Zika outbreak (as identified by Google Trends). Tweets were then filtered and entered in NVivo to be analysed using thematic analysis. It was found that tweets on Zika revolved around seven key themes: pregnancy, travel and the Olympics, mosquitoes and conspiracy, health organisations, health information, travel and tracking, and general discussions around Zika. Our results are likely to be of interest to public health organisations disseminating information related to future outbreaks of Zika and we develop a set of preliminary recommendations for health authorities