Search NASA⌕ Search

SEARCH · Search NASA

Results for “Association study”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,783 records · Page 99
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Reproductive intentions among HIV-negative gay and bisexual men initiating pre-exposure prophylaxis in the Sustainable Health Center Implementation pre-exposure prophylaxis pilot study, 2014–2016

Introduction We assessed reproductive intentions and associated characteristics among men enrolled in the Sustainable Health Center Implementation pre-exposure prophylaxis (PrEP) Pilot (SHIPP) Study. Methods We analyzed baseline data from 1275 men who self-identified as gay or bisexual and participated in the SHIPP study. SHIPP was a cohort study of PrEP implementation in five community health centers in Chicago, Jackson, Philadelphia, and Washington, D.C. conducted from 2014 to 2016. Participants completed audio computer-assisted self-interviews querying intentions to have a child in the future. We estimated the association between participants’ reproductive intentions and their characteristics using Poisson regression models. Results Approximately 47% of participants indicated their intentions to have a child. Black/non-Hispanic (aPR = 1.40; 95% CI: 1.10–1.78) and other/non-Hispanic participants (aPR = 1.40; 95% CI: 1.01–1.93) were more likely to report intentions to have a child than white/non-Hispanic participants. Participants were less likely to report intentions to have children as age increased (18–29 years, reference group; 30–39 years, aPR = 0.80, 95% CI: 0.64–0.99; 40–49 years, aPR = 0.49, 95% CI: 0.33–0.72; 50+ years, aPR = 0.07, 95% CI: 0.02–0.21). Conclusions Clinicians offering PrEP to black and other/non-Hispanic gay and bisexual men should assess their reproductive intentions as family-planning counseling may be an opportunity to introduce PrEP to HIV-negative gay and bisexual men.

Immunology↗
NASA NTRS1985

Remote detection of geobotanical anomalies associated with hydrocarbon microseepage

As part of the continuing study of the Lost River, West Virginia NASA/Geosat Test Case Site, an extensive soil gas survey of the site was conducted during the summer of 1983. This soil gas survey has identified an order of magnitude methane, ethane, propane, and butane anomaly that is precisely coincident with the linear maple anomaly reported previously. This and other maple anomalies were previously suggested to be indicative of anaerobic soil conditions associated with hydrocarbon microseepage. In vitro studies support the view that anomalous distributions of native tree species tolerant of anaerobic soil conditions may be useful indicators of methane microseepage in heavily vegetated areas of the United States characterized by deciduous forest cover. Remote sensing systems which allow discrimination and mapping of native tree species and/or species associations will provide the exploration community with a means of identifying vegetation distributional anomalies indicative of microseepage.

Rock, B. N.↗
DOE OSTI2012

Arthropod abundance and seasonal bird use of bottomland forest harvest gaps.

We investigated the influence of arthropod abundance and vegetation structure on shifts in avian use of canopy gap, gap edge, and surrounding forest understory in a bottomland hardwood forest in the Upper Coastal Plain of South Carolina. We compared captures of foliage-gleaning birds among locations during four periods (spring migration, breeding, post-breeding, and fall migration). Foliage arthropod densities were greatest in the forest understory in all four seasons, but understory vegetation density was greatest in gaps. Foliage-gleaning bird abundance was positively associated with foliage-dwelling arthropods during the breeding (F = 18.5, P < 0.001) and post-breeding periods (F = 9.4, P = 0.004), and negatively associated with foliage-dwelling arthropods during fall migration (F = 5.4, P = 0.03). Relationships between birds and arthropods were inconsistent, but the arthropod prey base seemed to be least important during migratory periods. Conversely, bird captures were positively correlated with understory vegetation density during all four periods (P < 0.001). Our study suggests high bird abundance associated with canopy gaps during the non-breeding period resulted less from high arthropod food resource availability than from complex understory and midstory vegetation structure.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Multi-omic characterization of bifunctional peroxidase 4-coumarate 3-hydroxylase knockdown in Brachypodium distachyon provides insights into lignin modification-associated pleiotropic effects

A bifunctional peroxidase enzyme, 4-coumarate 3-hydroxylase (C3H/APX), provides a parallel route to the shikimate shunt pathway for the conversion of 4-coumarate to caffeate in the early steps of lignin biosynthesis. Knockdown of C3H/APX (C3H/APX-KD) expression has been shown to reduce the lignin content in Brachypodium distachyon . However, like many other lignin-modified plants, C3H/APX-KDs show unpredictable pleiotropic phenotypes, including stunted growth, delayed senescence, and reduced seed yield. A system-wide level understanding of altered biological processes in lignin-modified plants can help pinpoint the lignin-modification associated growth defects to benefit future studies aiming to negate the yield penalty. Here, a multi-omic approach was used to characterize molecular changes resulting from C3H/APX-KD associated lignin modification and negative growth phenotype in Brachypodium distachyon . Our findings demonstrate that C3H/APX knockdown in Brachypodium stems substantially alters the abundance of enzymes implicated in the phenylpropanoid biosynthetic pathway and disrupt cellular redox homeostasis. Moreover, it elicits plant defense responses associated with intracellular kinases and phytohormone-based signaling to facilitate growth-defense trade-offs. A deeper understanding along with potential targets to mitigate the pleiotropic phenotypes identified in this study could aid to increase the economic feasibility of lignocellulosic biofuel production.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Pairing mechanism among ionic liquid ions in aqueous solutions. A molecular dynamics study

In this study, we carried out molecular dynamics simulations to examine the molecular mechanism for ionic liquid pair association in aqueous solutions. We chose the commonly studied imidazolium-based ionic liquid pairs. We computed potentials of mean force (PMF) for four systems—1,3-dimethlylimidazoliumchloride; 1,3-dimethlylimidazolium iodide; 1-methly-3-octylimidazolium chloride; and 1-methly-3-octylimidazolium iodide. Our PMF studies show a stronger interaction for the ion pairs of systems involving dimethlylimidazolium as the cation species compared to that of the systems containing octylimidazolium. This result indicates a decrease in ion-pair association as the cation alkyl tail length increases. We also studied the kinetics of ion-pair dissociation using different rate theories such as the Grote-Hynes and Kramer’s theories. As expected, the computed rate results significantly deviated from results obtained from transition state theory because it does not account for dynamical solvent effects. Dissociative barrier curvatures are found to be very small for the systems investigated because the transmission coefficients computed using Grote-Hynes theory and Kramer’s theory are approximately equal. Our analysis of the rotational dynamics of cations revealed that the time scales for molecular reorientation are longer for cations with longer alkyl tails. This work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences (BES), Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory is a multiprogram national laboratory operated for DOE by Battelle. The calculations were carried out using computer resources provided by BES.

Annapureddy, Harsha V.↗
DOE OSTI2017

Spliceosome-associated factor CTNNBL1 promotes proliferation and invasion in ovarian cancer

Ovarian cancer is the most lethal gynecologic malignancy and the molecular pathogenesis of high-grade serous ovarian carcinoma has not been completely characterized. Numerous studies have shown that altered splicing patterns and splicing factors were found to contribute to tumor development and progression. In this study, we demonstrated that spliceosome-associated factor CTNNBL1 was significantly upregulated in high-grade serous ovarian carcinoma, the elevated level of CTNNBL1 indicates poor prognosis in patients with high-grade serous ovarian carcinoma. Functional characterization revealed that CTNNBL1 promoted the proliferation and invasion of ovarian cancer cells in vitro. Furthermore, through transcriptome analysis, we found CTNNBL1 regulates multiple splicing events and gene expression in ovarian cancer cells. Importantly, we identified IFI16 and FOXM1 splicing was regulated by CTNNBL1. To our knowledge, this is the first study exploring the expression, functional roles and regulated splicing events of CTNNBL1 in ovarian cancer. - Highlights: • CTNNBL1 was upregulated in high-grade serous ovarian carcinoma and associated with poor prognosis. • CTNNBL1 promoted the proliferation and invasion of ovarian cancer cells in vitro. • Transcriptome analysis showed CTNNBL1 regulates multiple splicing events and gene expression in ovarian cancer cells. • FOXM1and IFI16 splicing were regulated by CTNNBL1.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Determination of the top-quark pole mass using tt¯ + 1-jet events collected with the ATLAS experiment in 7TeV pp collisions

In this study, the normalized differential cross section for top-quark pair production in association with at least one jet is studied as a function of the inverse of the invariant mass of the tt¯ + 1-jet system. This distribution can be used for a precise determination of the top-quark mass since gluon radiation depends on the mass of the quarks. The experimental analysis is based on proton-proton collision data collected by the ATLAS detector at the LHC with a centre-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.6 fb –1 . The selected events were identified using the lepton+jets top-quark-pair decay channel, where lepton refers to either an electron or a muon. The observed distribution is compared to a theoretical prediction at next-to-leading-order accuracy in quantum chromodynamics using the pole-mass scheme. With this method, the measured value of the top-quark pole mass, m pole t , is: m pole t = 173.7 ± 1.5(stat.) ± 1.4(syst.) +1.0 –0.5 (theory) GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

In situ measurements of a homogeneous to heterogeneous transition in the plastic response of ion-irradiated <111> Ni microspecimens

We report on the use of quantitative in situ microcompression experiments in a scanning electron microscope to systematically investigate the effect of self-ion irradiation damage on the full plastic response of <111> Ni. In addition to the well-known irradiationinduced increases in the yield and flow strengths with increasing dose, we measure substantial changes in plastic flow intermittency behavior, manifested as stress drops accompanying energy releases as the driven material transits critical states. At low irradiation doses, the magnitude of stress drops reduces relative to the unirradiated material and plastic slip proceeds on multiple slip systems, leading to quasi-homogeneous plastic flow. In contrast, highly irradiated specimens exhibit pronounced shear localization on parallel slip planes, which we ascribe to the onset of defect free channels normally seen in bulk irradiated materials. Our in situ testing system and approach allows for a quantitative study of the energy release and dynamics associated with defect free channel formation and subsequent localization. As a result, this study provides fundamental insight to the nature of interactions between mobile dislocations and irradiation-mediated and damage-dependent defect structures.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Geobotanical remote sensing for determination of aggregate source material

Aggregate source material suitable for facility and roadbed construction is often a very limited and highly valuable resource. The location of suitable source material is crucial to construction operations once facility requirements are established. The application of airborne and spaceborne remote sensing to terrain information requirements has proved attractive because of the rapid processing time and extensive spatial coverage associated with remotely gathered imagery. Source material identification may be improved by the remote sensing of vegetation associated with the material, particularly in areas of high vegetative cover. A research study employing remote sensing techniques was initiated to determine if vegetation could be used to discriminate parent materials for suitability as aggregate source material. Two test sites representing potential alluvial and residual source areas were selected in a semiarid region of Central California. Methods developed for the study included field observations of vegetation characteristics associated with the two parent material types along with the analysis of Thematic Mapper Simulator data flown over the test sites. The most useful images were those composites that included bands from two of the techniques (i.e., a Perpendicular Vegetation Index (PVI) band combined with principal components bands).

Minor, Timothy↗
DOE OSTI2023

Interactions among soil texture, pore structure, and labile carbon influence soil carbon gains

Perennial vegetation with high plant diversity, e.g., restored prairie, is known for stimulation of soil carbon (C) gains, due in part to enhanced formation of pore structure beneficial for long-term C storage. However, the prevalence of this phenomenon across soils of different types remains poorly understood. The aim of the study was to assess the associations between pore structure, soil C, and their differences in monoculture switchgrass and polyculture restored prairie vegetation across a wide range of soils dominating the Upper Midwest of the USA. Six experimental sites were sampled, representing three soil types with texture ranging from sandy to silt loams. The two vegetation systems studied at each site were (i) monoculture switchgrass (Panicum virgatum L.), and (ii) polyculture restored prairie, also containing switchgrass as one of its species. X-ray computed micro-tomography (µCT) was employed to analyze soil pore structure. Structural equation modeling and multiple path analyses were used to assess direct and indirect effects of soil texture and pore characteristics on microbial biomass C (MBC), particulate organic matter (POM), dissolved organic C (DOC), short-term respiration (CO 2 ), and, ultimately, soil organic C (SOC). Across studied sites, prairie increased fractions of medium (50–150 µm Ø) pores by 11–45 %, SOC by 3–69 %, and MBC by 18–59 % (except for one site). The greater were the prairie-induced increases in the medium pore volumes, the greater were the prairie-induced SOC gains. Greater C losses via CO 2 and DOC contributed to slower C accumulation in the prairie soil. We surmise that the interactive feedback loop relating medium pores and soil C acts across a wide range of soil textures and is an important mechanism through which perennial vegetation with high plant diversity, such as restored prairie, promotes rapid SOC gains.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Potential Chemical Impacts of CO2 Leakage on Underground Source of Drinking Water Assessed by Quantitative Risk Analysis

Many geologic carbon storage site options include not only excellent storage reservoirs bounded by effective seal layers, but also Underground Sources of Drinking Water (USDWs). An effective risk assessment and mitigation plan provides maximum protection for USDWs, to respect not only current policy but also to accommodate likely future USDW-specific regulatory protections. The goal of this study is to quantify possible risks to USDWs, specifically risks associated with chemical impacts on USDWs. Reactive transport models involve tremendous computational expense. Therefore, a secondary purpose of this study is to develop, calibrate and test reduced order models specifically for assessing risks of USDW chemical impacts by CO2 leakage from a storage reservoir. In order to achieve these goals, a geochemical model was developed to interpret changes in water chemistry following CO2 intrusion. A response surface methodology (RSM) based on these geochemical simulations was used to quantify associated risks. The case study example for this analysis is the Ogallala aquifer overlying the Farnsworth unit (FWU), an active commercial-scale CO2-enhanced oil recovery field. Specific objectives of this study include: (1) to understand how CO2 leakage is likely to influence geochemical processes in aquifer sediments; (2) to quantify potential risks to the Ogallala groundwater aquifer due to CO2 leakage from the FWU oil reservoir; and (3) to identify water chemistry factors for early detection criteria. Results indicate that the leakage rate would most likely range between 10-14 – 10-10 kg/(m2·year) for typical and likely leakage pathway permeability ranges. Within this range of CO2 leakage rate, groundwater quality is not likely to be significantly impacted. The worst-case scenario yields trace metal concentrations approximately twice as much as the initial value, but these predicted concentrations are still less than one-fifth of regulation-stipulated maximum contamination levels and do not exceed the no-impact thresholds. Finally, the results of this analysis suggest that pH may be an effective geochemical indicator of CO2 leakage.

CO2 leakage, USDWs, Groundwater quality, Risk anal↗
DOE OSTI2025

Security Assessment of an LBP16-Protocol-Based Computer Numerical Control Machine

Subtractive manufacturing systems, specifically, computer numerical control machines, have revolutionized the manufacturing industry. Computer numerical control machining is the preferred method for producing finished parts due to its efficiency, speed and suitability for high-volume production. Securing computer numerical control machines is a priority. Compromises or disruptions of these machines can result in significant downtime, loss of productivity and financial loss. This study examines the vulnerabilities and risks associated with computer numerical control machines, in particular, systems utilizing the LBP16 protocol for controller-machine communications. The study reveals that an adversary can execute cyber-physical attacks such as sabotage and denial of service. The potential security threats emphasize the importance of implementing robust security measures to mitigate the cyber risks to computer numerical control machines.

Forihat, Yahya [Virginia Commonwealth University, ↗
DOE OSTI2021

Electroweak Currents from Chiral Effective Field Theory

Since the pioneering work of Weinberg, Chiral Effective Field Theory (EFT) has been widely and successfully utilized in nuclear physics to study many-nucleon interactions and associated electroweak currents. Here, nuclear EFT has now developed into an intense field of research and is applied to study light to medium mass nuclei. In this contribution, we focus on the development of electroweak currents from EFT and present applications to selected nuclear electroweak observables.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Marginal Damage of Methane Emissions: Ozone Impacts on Agriculture

Methane directly contributes to air pollution, as an ozone precursor, and to climate change, generating physical and economic damages to different systems, namely agriculture, vegetation, energy, human health, or biodiversity. The methane-related damages to climate, measured as the Social Cost of Methane, and to human health have been analyzed by different studies and considered by government rulemaking in the last decades, but the ozone-related damages to crop revenues associated to methane emissions have not been incorporated to policy agenda. Using a combination of the Global Change Analysis Model and the TM5-FASST Scenario Screening Tool, we estimate that global marginal agricultural damages range from ~ 423 to 556 $2010/t-CH 4 , of which 98 $2010/t-CH 4 occur in the USA, which is the most affected region due to its role as a major crop producer, followed by China, EU-15, and India. These damages would represent 39–59% of the climate damages and 28–64% of the human health damages associated with methane emissions by previous studies. The marginal damages to crop revenues calculated in this study complement the damages from methane to climate and human health, and provides valuable information to be considered in future cost-benefits analyses.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

TRIM16 overexpression inhibits the metastasis of colorectal cancer through mediating Snail degradation

Highlights: • TRIM16 does significantly inhibit CRC cell migration and metastasis. • TRIM16 negatively regulates CRC cells EMT. • TRIM16 directly interacts with Snail. • TRIM16 promotes degradation of Snail via ubiquition proteasome pathway. Tripartite motif containing 16 (TRIM16) is a member of the tripartite motif protein family and functions as a potential tumor suppressor in several cancers. However, the specific function and clinical significance of TRIM16 in colorectal cancer (CRC) remains unclear. In this study, we observed that low TRIM16 expression was detected frequently in primary colorectal cancer (CRC) tissues and was closely associated with a better prognosis. Functional studies demonstrate that TRIM16 overexpression notably inhibits the metastasis abilities of CRC in vivo and in vitro. Mechanistically, our results demonstrated that TRIM16 directly bound and ubiquitinated Snail family transcriptional repressor 1 (Snail), an important transcriptional factor of the epithelial-mesenchymal transition (EMT) process suppressing the EMT in CRC. Additionally, our data revealed that the inhibition effect of TRIM16 on cancer metastasis was dependent on Snail degradation. Collectively, our study is the first to report that TRIM16 plays a crucial anti-tumor role in CRC tumorigenesis. We also provided novel evidence that TRIM16 might act as a prognostic and therapeutic target to assess and inhibit CRC progression.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

An Analysis of Thermal Plant Flexibility Using a National Generator Performance Database

Grid integration studies are key to understanding our ability to integrate variable generation resources into the power system and evaluating the associated costs and benefits. In these studies, it is important to understand the flexibility of the thermal power fleet, including how thermal plants operate at part load. Without a comprehensive understanding of thermal plant operation, we may over- or underestimate our ability to integrate variable generation resources and thus draw incomplete or inaccurate conclusions regarding their potential economic and environmental effects. The only public data source for understanding many elements of the operational characteristics of the thermal fleet is the U.S. Environmental Protection Agency Clean Air Markets database of historical power plant operation. However, though these data sets have been widely utilized, their use has proven to be difficult, and methods to clean and filter the data are not transparent. Here, we describe the database and a method to clean and filter it. We then use the cleaned database to demonstrate several characteristics of historical plant operation, including frequent part load operation. Finally, we provide a cleaned data set with heat rate curves and describe how to use it in general modeling activities and analysis.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

Reliability, stability during long-term storage, and intra-individual variation of circulating levels of osteopontin, osteoprotegerin, vascular endothelial growth factor-A, and interleukin-17A

Background: Studies in many populations have reported associations between circulating cytokine levels and various physiological or pathological conditions. However, the reliability of cytokine measurements in population studies, which measure cytokines in multiple assays over a prolonged period, has not been adequately examined; nor has stability during sample storage or intra-individual variation been assessed. Methods: We assessed (1) analytical reliability in short- and long-term repeated measurements; (2) stability and analytical reliability during long-term sample storage, and (3) variability within individuals over seasons, of four cytokines—osteopontin (OPN), osteoprotegerin (OPG), vascular endothelial growth factor-A (VEGF-A), and interleukin-17A (IL-17A). Measurements in plasma or serum samples were made with commercial kits according to standard procedures. Estimation was performed by fitting a random or mixed effects linear model on the log scale. Results: In repeated assays over a short period, OPN, OPG, and VEGF-A had acceptable reliability, with intra- and inter-assay coefficients of variation (CV) less than 0.11. Reliability of IL-17A was poor, with inter- and intra-assay CV 0.85 and 0.43, respectively. During long-term storage, OPG significantly decayed (-33% per year; 95% confidence interval [-54, -3.7]), but not OPN or VEGF-A (-0.3% or -6.3% per year, respectively). Intra- and inter-assay CV over a long period were comparable to that in a short period except for a slight increase in inter-assay CV of VEGF-A. Within-individual variation was small for OPN and VEGF-A, with intra-class correlations (ICC) 0.68 and 0.83, respectively, but large for OPG (ICC 0.11). Conclusions: We conclude that OPN and VEGF-A can be reliably measured in a large population, that IL-17A is suitable only for small experiments, and that OPG should be assessed with caution due to degradation during storage and intra-individual variation. The overall results of our study illustrate the need for validation under relevant conditions when measuring circulating cytokines in population studies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Peripherally Inserted Central Catheters in Pediatric Patients: To Repair or Not Repair

IntroductionPreservation of venous access in children is a major concern in pediatric interventional radiology. If a peripherally inserted central catheter (PICC) breaks, there are two options: repair the line with a repair kit or exchange the line over a wire in the interventional suite. The purpose of this study is to assess the outcome of PICC repairs in children and to compare these with the outcomes of PICC exchange.Materials and MethodsThis is a single-center, retrospective study of central line-associated bloodstream infection (CLABSI) following management of externally broken PICCs (2010–2014). The occurrence of CLABSI within 30 days after repair (Group A) or exchange (Group B) of a line was analyzed, as well as PICCs exchanged following an initial and failed repair.ResultsA total of 235 PICC breaks were included in the study, of which 161 were repaired, and 116 of whom were successful (68%, Group A). No repair was performed in 74 PICCs—55/74 of these were exchanged over a wire (74%, Group B), and 19/74 lines were removed. The 30 days post-repair CLABSI rate (Group A) was 2.0 infections per 1000 catheter days, and the calculated risk was 4.3%. In comparison the 30 days post-exchange CLABSI rate (Group B) was 4.0 per 1000 catheter days and the calculated risk 10.9%. This difference was significant when adjusted for antibiotic use (OR 3.87; 95% CI 1.07–14.0, p = 0.039).ConclusionThe results of this study support repairing a broken PICC instead of removing or replacing the line.

62 RADIOLOGY AND NUCLEAR MEDICINE↗