Search Results (26)

The Tungnárhraun basalts in southern Iceland record a transcrustal magma system formed during Holocene deglaciation. These large-volume (>1 km³) Early through Mid-Holocene lavas contain ubiquitous plagioclase feldspar macrocrysts that are too primitive to have grown from the host lavas. Thermobarometry based on plagioclase melt and clinopyroxene melt equilibrium reveals a transcrustal structure with at least three distinct storage regions. A lower-crustal mush zone at ~14–30 km is fed by primitive, low ⁸⁷Sr/⁸⁶Sr magmas with diverse Ti/K and Al/Ti signatures. Plagioclase feldspar growth is controlled by an experimentally determined pseudoazeotrope where crystals develop inversely correlated An and Mg contents. The rapid ascent of magmas to mid-crustal levels (~8–9 km) allows the feldspar system to revert to conventional thermodynamic phase constraints. Continued plagioclase growth releases heat, causing olivine and pyroxene to be resorbed and giving the magmas their characteristic high CaO/Al₂O₃ values (~0.8–1.0) and Sc contents (~52 ppm in matrix material). Mid-Holocene MgO-rich lavas with abundant plagioclase feldspar macrocrysts erupted directly from this depth, but both older and younger magmas ascended to a shallow-crustal storage chamber (~5 km) where they crystallized olivine, clinopyroxene, and plagioclase feldspar and evolved to lower MgO contents. The Sr isotope differences between the plagioclase macrocrysts and their carrier melts suggest that the fractionation involves the minor assimilation of country rock. This model does not require the physical disruption of an established and long-lived gabbroic cumulate mush. The transcrustal structures documented here existed in south Iceland at least throughout the Holocene and likely influenced much of Icelandic magmatism. Full article

This study investigates the effect of geological field measurement (offset), global positioning system (GPS), and interferometric synthetic aperture radar (InSAR) data on the estimation of the co-seismic earthquake displacements of the 2002 Denali earthquake. The analysis is conducted using stochastic source modeling. Uncertainties associated with each dataset limit their effectiveness in source model selection and raise questions about the adequate number of datasets and their type for reliable source estimation. To address these questions, stochastic source models with heterogeneous earthquake slip distributions are synthesized using the von Kármán wavenumber spectrum and statistical scaling relationships. The surface displacements of the generated stochastic sources are obtained using the Okada method. The surface displacements are compared with the available datasets (i.e., offset, GPS, and InSAR) individually and in an integrated form. The results indicate that the performance of stochastic source generation can be significantly improved in the case of using GPS data and in the integrated case. Overall, based on the case study of the 2002 Denali earthquake, the combined use of all available datasets increases the robustness of the stochastic source modeling method in characterizing surface displacement. However, GPS data contribute more than InSAR and offset data in producing reliable source models. Full article

A systematic literature review was conducted to determine the global status of newborn screening (NBS) for mucopolysaccharidosis (MPS) II (Hunter syndrome; OMIM 309900). Electronic databases were searched in July 2023 for articles referencing NBS for lysosomal storage diseases: 53 featured MPS II. Until recently, only Taiwan and two US states (Illinois and Missouri) formally screened newborns for MPS II, although pilot programs have been conducted elsewhere (Japan, New York, and Washington). In 2022, MPS II was added to the US Recommended Uniform Screening Panel, with increased uptake of NBS anticipated across the USA. While the overall MPS II birth prevalence, determined from NBS initiatives, was higher than in previous reports, it was lower in the USA (approximately 1 in 73,000 according to recent studies in Illinois and Missouri) than in Asia (approximately 1 in 15,000 in Japan). NBS programs typically rely on tandem mass spectrometry quantification of iduronate-2-sulfatase activity for first-tier testing. Diagnosis is often confirmed via molecular genetic testing and/or biochemical testing but may be complicated by factors such as pseudodeficiency alleles and variants of unknown significance. Evidence relating to MPS II NBS is lacking outside Taiwan and the USA. Although broad benefits of NBS are recognized, few studies specifically explored the perspectives of families of children with MPS II. Full article

There has been a growth in the number of composite indicator tools used to assess community risk, vulnerability, and resilience, to assist study and policy planning. However, existing research shows that these composite indicators vary extensively in method, selected variables, aggregation methods, and sample size. The result is a plethora of qualitative and quantitative composite indices to choose from. Despite each providing valuable location-based information about specific communities and their qualities, the results of studies, each using disparate methods, cannot easily be integrated for use in decision making, given the different index attributes and study locations. Like many regions in the world, the Arctic is experiencing increased variability in temperatures as a direct consequence of a changing planetary climate. Cascading effects of changes in permafrost are poorly characterized, thus limiting response at multiple scales. We offer that by considering the spatial interaction between the effects of permafrost, infrastructure, and diverse patterns of community characteristics, existing research using different composite indices and frameworks can be augmented. We used a system-science and place-based knowledge approach that accounts for sub-system and cascade impacts through a proximity model of spatial interaction. An estimated ‘permafrost vulnerability surface’ was calculated across Alaska using two existing indices: relevant infrastructure and permafrost extent. The value of this surface in 186 communities and 30 military facilities was extracted and ordered to match the numerical rankings of the Denali Commission in their assessment of permafrost threat, allowing accurate comparison between the permafrost threat ranks and the PVI rankings. The methods behind the PVI provide a tool that can incorporate multiple risk, resilience, and vulnerability indices to aid adaptation planning, especially where large-scale studies with good geographic sample distribution using the same criteria and methods do not exist. Full article

The Cantwell Formation of the central Alaska Range provides a robust archive of high-latitude, Late Cretaceous depositional systems and paleo-floral/faunal assemblages. Our stratigraphic analysis defines two mappable members. The lower member (1500–2000 m thick) represents vegetated alluvial fan and braided fluvial systems that transition up-section to fluvial–estuarine systems that drained into an inland continental seaway. The upper member (~2000 m thick) represents estuarine–marginal marine and lacustrine systems. Previous paleontological studies demonstrate that the Cantwell basin was populated by various dinosaurs, fishes, bivalves, birds, and marginal marine micro-organisms. Integration of new and published geologic mapping allows for reconstruction of depositional systems at the basin scale and provides additional paleogeographic context. The northern basin margin was defined by a previously unrecognized south-verging thrust belt, whereas the southern margin of the basin was defined by a north-verging thrust belt inboard of an active magmatic arc. Sediment sources interpreted from U-Pb detrital zircon geochronology included the coeval magmatic arc and older Cretaceous plutons, and Proterozoic–Mesozoic strata exhumed along the basin margins. Results of our study provide a depositional, stratigraphic, and structural framework that may serve as a guide for future paleontological and paleoclimatic investigations of Late Cretaceous Arctic environments of the Cantwell basin. Full article

This study aimed to investigate four dental adhesive cements and develop a new method for constructing a bi-layered bone holder for implant testing. Hahn^TM Tapered Titanium Implants (Glidewell Laboratories) were embedded in mono- and bi-layered holders, and the implant components were assembled. First molar zirconia crowns and crowns for the tensile bond strength test were milled and sintered. Three self-adhesive resin cements (SARC) and one resin-modified glass ionomer (RMGI, Glidewell Laboratories) cement were used to cement the crowns on the abutment. Tensile bond strength, compressive load, and oblique load tests were performed on the implants. The Glidewell Experimental SARC (GES, Glidewell Laboratories) and RMGI cements had the highest tensile bond strength after thermocycling. The implant assemblies with these two cements had the highest mean compressive strength after thermocycling. Under oblique load, the implants with Denali (Glidewell Laboratories) and GES had the highest strength before thermocycling. However, after thermocycling, Dencem (Dentex) and RMGI had the highest strength under an oblique load. The GES cement and RMGI cement had a better overall performance with zirconia crowns and titanium abutments. In addition, a novel technique for constructing an artificial, bi-layered bone holder was successfully developed to mimic the natural structure of the jawbone. Full article

Landslides along road corridors in Alaska national parks pose threats to public safety, visitor access, subsistence activities, and result in costly remediation of damaged infrastructure. Landslide risk in these areas, which contain near-surface permafrost, is associated with mean annual air temperatures (MAATs) above freezing and heavy precipitation events. Historical (1981–2020) values of MAAT and summer precipitation (JJA PCPT) from the fifth generation European Centre for Medium-Range Weather Forecasts (Reading, UK) atmospheric reanalysis (ERA5) were compared to mid-century (2021–2060) and late-century (2061–2100) downscaled climate model projections across Gates of the Arctic National Park and Preserve (GAAR), Denali National Park and Preserve (DENA), and Wrangell-St. Elias National Park and Preserve (WRST). ERA5 showed that all locations historically had MAAT values below freezing, but all three parks were warming significantly (0.3–0.6 °C per decade). Observed trends of MAAT from 18 stations showed warming trends with 11 of the 18 being significant at the 95% confidence level using the Mann–Kendall non-parametric test. Road corridor values are given for the: (1) proposed Ambler Road through GAAR, (2) Denali Park Road in DENA, and (3) McCarthy Road in WRST. Elevated risk from MAAT was projected in the mid-century period for the Denali Park Road and McCarthy Road and across all three park road corridors in the late-century period; elevated risk from JJA PCPT was projected in all periods for all road corridors. Full article

Background: Improvement of oxygenation is the aim in the therapy of high-altitude pulmonary edema (HAPE). However, descent is often difficult and hyperbaric chambers, as well as bottled oxygen, are often not available. We compare Auto-PEEP (AP-Pat), a special kind of pursed lips breathing, against the application of bottled oxygen (O₂-Pat) in two patients suffering from HAPE. Methods: We compare the effect of these two different therapies on oxygen saturation measured by pulse oximetry (SpO₂) over time. Result: In both patients SpO₂ increased significantly from 65–70% to 95%. Above 80% this increase was slower in AP-Pat compared with O₂-Pat. Therapy started immediately in AP-Pat but was delayed in O₂-Pat because of organizational and logistic reasons. Conclusions: The well-established therapies of HAPE are always the option of choice, if available, and should be started as soon as possible. The advantage of Auto-PEEP is its all-time availability. It improves SpO₂ nearly as well as 3 L/min oxygen and furthermore has a positive effect on oxygenation lasting for approximately 120 min after stopping. Auto-PEEP treatment does not appear inferior to oxygen treatment, at least in this cross-case comparison. Its immediate application after diagnosis probably plays an important role here. Full article

Sustainable development of Canada’s North requires an increased focus on renewable, zero-emission energy sources. Burwash Landing in Yukon is prospective for geothermal energy based on a high geothermal gradient, local occurrence of warm groundwater and proximity to the active, crustal-scale Denali fault. Uncertainties about the potential geothermal system include the nature and geometry of fluid pathways, and heat sources required to drive a hydrothermal system. In this study, we inverted three passive electromagnetic datasets—321 extremely low frequency electromagnetic, 33 audiomagnetotelluric and 51 magnetotelluric stations—to map the subsurface electrical structure to 8 km depth. Our new model reveals vertical conductive structures associated with the two main faults, Denali and Bock’s Creek, which we interpret to represent fluid-deposited graphite and hydrothermal alteration, respectively. Our model supports an interpreted releasing bend on the main Denali fault strand. This is associated with the deepest conductivity anomaly along the fault and potential for deeper penetration of fluids. Enigmatic conductive bodies from 1 to > 6 km depth are associated with intermediate to mafic intrusions. Fluids released from these bodies may advect heat and provide a possible heat source to mobilize hot fluids and sustain a geothermal system in the region. Full article

Outdoor recreation continues to be persistently high in national parks across the United States, particularly as the COVID-19 pandemic has led to increased use. In popular frontcountry destinations such as national park campgrounds managers are challenged with new issues more familiar to urban settings. One of these challenges is waste management. The largest source of visitor-generated waste in national parks is campgrounds. This research uses a mixed-methods approach to develop and test strategic communications designed to increase recycling and minimize trash to the landfill by altering campground visitor behaviors. Intercept surveys were used to create theory-based messages, and a quasi-experimental approach was used to evaluate message effectiveness. Our results show that messages emphasizing ease concepts were two times more effective at changing campground visitor waste disposal behaviors than control conditions. The results help inform the management of visitors as national parks strive to meet sustainability goals. Full article

Autosomal-recessive cerebellar ataxias (ARCAs) are heterogeneous rare disorders mainly affecting the cerebellum and manifest as movement disorders in children and young adults. To date, ARCA causing mutations have been identified in nearly 100 genes; however, they account for less than 50% of all cases. We studied a multiplex, consanguineous Pakistani family presenting with a slowly progressive gait ataxia, body imbalance, and dysarthria. Cerebellar atrophy was identified by magnetic resonance imaging of brain. Using whole exome sequencing, a novel homozygous missense mutation ERCC8:c.176T>C (p.M59T) was identified that co-segregated with the disease. Previous studies have identified homozygous mutations in ERCC8 as causal for Cockayne Syndrome type A (CSA), a UV light-sensitive syndrome, and several ARCAs. ERCC8 plays critical roles in the nucleotide excision repair complex. The p.M59T, a substitution mutation, is located in a highly conserved WD1 beta-transducin repeat motif. In silico modeling showed that the structure of this protein is significantly affected by the p.M59T mutation, likely impairing complex formation and protein-protein interactions. In cultured cells, the p.M59T mutation significantly lowered protein stability compared to wildtype ERCC8 protein. These findings expand the role of ERCC8 mutations in ARCAs and indicate that ERCC8-related mutations should be considered in the differential diagnosis of ARCAs. Full article

Permafrost formation and degradation creates a highly patchy mosaic of boreal peatland ecosystems in Alaska driven by climate, fire, and ecological changes. To assess the biophysical factors affecting permafrost dynamics, we monitored permafrost and ecological conditions in central Alaska from 2005 to 2021 by measuring weather, land cover, topography, thaw depths, hydrology, soil properties, soil thermal regimes, and vegetation cover between burned (1990 fire) and unburned terrain. Climate data show large variations among years with occasional, extremely warm–wet summers and cold–snowless winters that affect permafrost stability. Microtopography and thaw depth surveys revealed both permafrost degradation and aggradation. Thaw depths were deeper in post-fire scrub compared to unburned black spruce and increased moderately during the last year, but analysis of historical imagery (1954–2019) revealed no increase in thermokarst rates due to fire. Recent permafrost formation was observed in older bogs due to an extremely cold–snowless winter in 2007. Soil sampling found peat extended to depths of 1.5–2.8 m with basal radiocarbon dates of ~5–7 ka bp, newly accumulating post-thermokarst peat, and evidence of repeated episodes of permafrost formation and degradation. Soil surface temperatures in post-fire scrub bogs were ~1 °C warmer than in undisturbed black spruce bogs, and thermokarst bogs and lakes were 3–5 °C warmer than black spruce bogs. Vegetation showed modest change after fire and large transformations after thermokarst. We conclude that extreme seasonal weather, ecological succession, fire, and a legacy of earlier geomorphic processes all affect the repeated formation and degradation of permafrost, and thus create a highly patchy mosaic of ecotypes resulting from widely varying ecological trajectories within boreal peatland ecosystems. Full article

Frequent acquisition of Synthetic Aperture Radar (SAR) data by the European Sentinel-1 satellites provides an opportunity for monitoring the dynamics of worldwide glaciers. We present a fully-automated processing system for producing multi-dimensional time series of glacier flow. We then use this fully-automated processing system to investigate the dynamics of Muldrow Glacier, located in the Denali National Park and Preserve (Alaska, AK, USA) during the October 2014—November 2021 period. We compute north, east, and vertical Surface-Parallel-Flow (SPF) and non-Surface-Parallel-Flow (nSPF) components of flow velocity and displacement with an average temporal resolution of 9 days and grid spacing of 100 m. During this period, we observe a glacier surge, a manifold increase in glacier flow velocity, that started as early as 2017 and continues until the present; however, the near completion of this surge is apparent. This glacier previously surged in 1906–1912 (the exact date is unknown) and in 1956–1957. We present our results in different ways to emphasize various aspects of the observed surge and demonstrate the full capability of our processing system. As the availability of SAR data improves, we expect that the fully-automated processing systems, similar to the one presented here, will play an increasingly dominant role and soon entirely replace manual processing. Full article

The partially correlative Alaskan dinosaur-bearing Prince Creek Formation (PCF), North Slope, lower Cantwell Formation (LCF), Denali National Park, and Chignik Formation (CF), Aniakchak National Monument, form an N–S transect that, together, provides an unparalleled opportunity to examine an ancient high-latitude terrestrial ecosystem. The PCF, 75–85° N paleolatitude, had a Mean Annual Temperature (MAT) of ~5–7 °C and a Mean Annual Precipitation (MAP) of ~1250 mm/year. The LCF, ~71° N paleolatitude, had a MAT of ~7.4 °C and MAP of ~661 mm/year. The CF, ~57° N paleolatitude, had a MAT of ~13 °C and MAP of ~1090 mm/year. The relative abundances of the large-bodied herbivorous dinosaurs, hadrosaurids and ceratopsids, vary along this transect, suggesting that these climatic differences (temperature and precipitation) played a role in the ecology of these large-bodied herbivores of the ancient north. MAP played a more direct role in their distribution than MAT, and the seasonal temperature range may have played a secondary role. Full article

Multiple lines of evidence suggest that a deficiency of Fragile X Mental Retardation Protein (FMRP) mediates dysfunction of the metabotropic glutamate receptor subtype 5 (mGluR₅) in the pathogenesis of fragile X syndrome (FXS), the most commonly known single-gene cause of inherited intellectual disability (ID) and autism spectrum disorder (ASD). Nevertheless, animal and human studies regarding the link between FMRP and mGluR₅ expression provide inconsistent or conflicting findings about the nature of those relationships. Since multiple clinical trials of glutamatergic agents in humans with FXS did not demonstrate the amelioration of the behavioral phenotype observed in animal models of FXS, we sought measure if mGluR₅ expression is increased in men with FXS to form the basis for improved clinical trials. Unexpectedly marked reductions in mGluR₅ expression were observed in cortical and subcortical regions in men with FXS. Reduced mGluR₅ expression throughout the living brains of men with FXS provides a clue to examine FMRP and mGluR₅ expression in FXS. In order to develop the findings of our previous study and to strengthen the objective tools for future clinical trials of glutamatergic agents in FXS, we sought to assess the possible value of measuring both FMRP levels and mGluR₅ expression in men with FXS. We aimed to show the value of measurement of FMRP levels and mGluR₅ expression for the diagnosis and treatment of individuals with FXS and related conditions. We administered 3-[¹⁸F]fluoro-5-(2-pyridinylethynyl)benzonitrile ([¹⁸F]FPEB), a specific mGluR₅ radioligand for quantitative measurements of the density and the distribution of mGluR₅s, to six men with the full mutation (FM) of FXS and to one man with allele size mosaicism for FXS (FXS-M). Utilizing the seven cortical and subcortical regions affected in neurodegenerative disorders as indicator variables, adjusted linear regression of mGluR₅ expression and FMRP showed that mGluR₅ expression was significantly reduced in the occipital cortex and the thalamus relative to baseline (anterior cingulate cortex) if FMRP levels are held constant (F(7,47) = 6.84, p < 0.001).These findings indicate the usefulness of cerebral mGluR₅ expression measured by PET with [¹⁸F]FPEB and FMRP values in men with FXS and related conditions for assessments in community facilities within a hundred-mile radius of a production center with a cyclotron. These initial results of this pilot study advance our previous study regarding the measurement of mGluR₅ expression by combining both FMRP levels and mGluR₅ expression as tools for meaningful clinical trials of glutamatergic agents for men with FXS. We confirm the feasibility of this protocol as a valuable tool to measure FMRP levels and mGluR₅ expression in clinical trials of individuals with FXS and related conditions and to provide the foundations to apply precision medicine to tailor treatment plans to the specific needs of individuals with FXS and related conditions. Full article