Arconic (United States)

Abstract The dominant conceptual model for how river flow affects when and where riparian hardwood trees establish (the “recruitment box model”) considers streamflow recession and a survivable rate of stage decline to predict survival of seedling desiccation. However, to become established, plants must also survive the pre‐seedling life stages and avoid inundation and scour mortality in high flows. We examine the relative importance of these flow‐dependent mechanisms by representing them in a two‐dimensional simulation model. Analysis of the model as applied to a low‐gradient reach of a large mountain river indicates that the soil characteristic determining moisture elevation (the “capillary fringe” height) is the most important process driving establishment rates; also important are the dates of seed deposition, inundation mortality, and the time needed for sprouted seeds to develop roots. Root growth rate had only moderate effect on seedling survival. These results indicate that the conventional conceptual model of establishment is incomplete. At our site, natural rates of decline in soil moisture elevation exceeded root growth rates, so widespread establishment required periods of near‐steady flows. Further, under both reservoir‐controlled and unimpaired flow regimes, establishment was strongly determined by post‐deposition flow increases: seeds deposited at elevations low enough to support rooting were often killed via inundation or scour in flow fluctuations that occurred under both reservoir‐regulated and unregulated flow scenarios. When soil moisture dynamics are represented even simply, the survivable rate of stage decline is not constant but depends on capillary fringe height, seed elevation, and the duration of stage decline. A more complete conceptual model of hardwood establishment considers that seeds need to be deposited where soil is moist long enough to develop roots but far enough from the water's edge to avoid mortality in flow fluctuations; for soil moisture to remain within reach of roots, which could require unusually steady flows, a high capillary fringe, or favorable groundwater gradients; and to avoid mortality due to scour or inundation in winter high flows. Model sensitivity and lack of literature suggest the time and moisture requirements for seeds to develop roots and inundation mortality of seedlings as research priorities.

Over the past 20 years, the Immune Epitope Database (IEDB, iedb.org) has established itself as the foremost resource for immune epitope data. The IEDB catalogs published epitopes and their contextual experimental data in a freely searchable public resource. The IEDB team manually curates data from the literature into a structured format and spans infectious, allergic, autoimmune, and transplant diseases. Here, we describe the enhancements made since our 2018 paper, capturing user-directed updates to the search interface, advanced data exports, increases in data quality, and improved interoperability across related resources. As we look forward to the next 20 years, we are confident in our ability to meet the needs of our users and to contribute to the broader field of data standardization.

Background In 2020, there were 36.7 million reported falls among older adults (65+) in the United States. Ethanol and other sedating substances may increase fall risk among older adults due to their effect on cognitive and physical function. We estimate the prevalence of these substances in blood specimens of older adults presenting with a fall injury at selected trauma centers. Methods The initial study collected blood specimens from May 2020 through July 2021 from adults undergoing a trauma team evaluation at selected United States Level 1 trauma centers. We limited our study to older adults evaluated after a fall (n = 1,365) and selected a random sample (n = 300) based on age, sex, and trauma-center quotas. Medical health records and blood specimens obtained at trauma center presentation were analyzed. We estimated the prevalence of ethanol, benzodiazepines, cannabinoids, and opioids in the blood specimens. Two-sample tests of binomial proportions and Chi-square two-tailed tests were used to compare prevalence estimates of substances by demographic characteristics. Results At least one substance was detected among 31.3% of samples analyzed. Prevalences of specific substances detected were 9.3% (95% CI: 6.0–12.6%) for benzodiazepines, 4.3% (95% CI: 2.0–6.7%) for cannabinoids, 8.0% (95% CI: 5.2–11.7%) for ethanol, and 15.0% (95% CI: 10.9–19.1%) for opioids. There were 18 deaths (6%; 95% CI: 3.6–9.3%). One-third of decedents had at least one substance detected in their blood. Discussion Opioids were the most frequently detected substance, followed by benzodiazepines, ethanol, and cannabinoids. Substance use prevalence was not uniform across demographics, with differences observed by sex and age. Conclusions This study provides insight into the frequency of the presence of substances that may contribute to fall risk and serious injury among older adults. Screening older adults for substances that impair cognitive and physical function can enhance clinical fall prevention efforts.

BackgroundPopulation-based seroprevalence studies offer comprehensive characterization of coronavirus disease 2019 (COVID-19) spread, but barriers exist and marginalized populations may not be captured. We assessed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody seroprevalence among decedents in Maryland over 6 months in 2020.MethodsData were collected on decedents undergoing forensic postmortem examination in Maryland from 24 May through 30 November 2020 from whom a blood specimen could be collected. Those with available blood specimens were tested with the CoronaCHEK lateral flow antibody assay. We assessed monthly seroprevalence compared to the statewide estimated number of cases and proportion of positive test results (testing positivity). We used Poisson regression with robust variance to estimate adjusted prevalence ratios (aPRs) with 95% confidence intervals (CIs) for associations of demographic characteristics, homelessness, and manner of death with SARS-CoV-2 antibodies.ResultsAmong 1906 decedents, 305 (16%) were positive for SARS-CoV-2 antibodies. Monthly seroprevalence increased from 11% to 22% over time and was consistently higher than state-level estimates of testing positivity. Hispanic ethnicity was associated with 2- to 3.2-fold higher seropositivity (P < .05) irrespective of sex. Deaths due to motor vehicle crash were associated with 62% increased seropositivity (aPR, 1.62 [95% CI, 1.15–2.28]) vs natural manner of death. Though seroprevalence was lower in decedents of illicit drug overdose vs nonoverdose in early months, this shifted, and seroprevalence was comparable by November 2020.ConclusionsDecedents undergoing forensic postmortem examination, especially those dying due to motor vehicle trauma, may be a sentinel population for COVID-19 spread in the general population and merits exploration in other states/regions.

Substantial progress has continued in the US since the last (13th) World Titanium Conference with regards to titanium technology, products, processing, computational modeling tools and applications. Titanium components produced by additive manufacturing have been qualified and achieved production applications in commercial and military aircraft hardware. New high-performance titanium alloys have been developed for higher temperature service and applications requiring more demanding static and dynamic properties. Current production processes for titanium have been optimized, and new processes have been developed to further reduce cost and improve product quality. Titanium suppliers, OEM’s, government labs and academia are working closely together to address fundamental industry-wide issues. Computer modeling is now used extensively in industrial and research facilities to accelerate the pace and success of these developments.

A summar y of the final progress achieved in two Metals Affordability Initiative (MAI) programs (RR-12 and RR-13) that were funded by the US Air Force to develop the necessary integrated computational materials engineering (ICME) framework, knowledge, and supporting database to model and predict location-specific fatigue properties across the entire titanium supply chain is presented. Validation of this ICME framework which allows for the prediction of location specific low cycle fatigue (LCF) and high cycle fatigue (HCF) behavior on complex production components in electro-polished and shot peened surface conditions will be presented. In addition, validation of a new shot peening capability embedded with the commercial software package DEFORM™ will be presented.

Abstract Recently proposed modifications to ASTM E399, Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness KIc of Metallic Materials, would provide a new size-insensitive approach to analyzing the force-displacement test record. The proposed size-insensitive linear-elastic fracture toughness, KIsi, targets a consistent 0.5-mm crack extension for all specimen sizes by using an offset secant that is a function of the specimen ligament length. With intent to increase flexibility in the test method, the KIsi evaluation method removes the Pmax/PQ criterion, which can penalize materials with rising tearing resistance curves, and increases the limits on specimen deformation, which allows more plasticity at the crack tip at the onset of crack extension. The primary motivation for this investigation is to confirm the validity of this new interpretation of the force-displacement test record in regard to the increase in acceptable specimen deformation. This article summarizes a finite element study of the effects of increased crack tip plasticity on the KIsi evaluation method, with two primary points of investigation: the continued validity of linear-elastic fracture mechanics (LEFM) to describe the crack front conditions and the effect of crack tip plasticity on compliance change in the force-displacement record. The analytical study illustrates that LEFM assumptions remain valid at the increased deformation limit; however, the influence of plasticity on the compliance change in the test record is problematic. A proposed revision to the validity criteria for the KIsi test method is described.