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All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Quantifying and reducing the differences in forest CO 2 -fluxes estimated by eddy covariance, biometric and chamber methods: A global synthesis

Carbon dioxide (CO 2 ) fluxes between terrestrial ecosystems and the atmosphere are primarily measured with eddy covariance (EC), biometric, and chamber methods. However, it is unclear why the estimates of CO 2 -fluxes, when measured using these different methods, converge at some sites but diverge at others. We synthesized a novel global dataset of forest CO 2 -fluxes to evaluate the consistency between EC and biometric or chamber methods for quantifying CO 2 budget in forests. The EC approach, comparing with the other two methods, tended to produce 25% higher estimate of net ecosystem production (NEP, 0.52Mg C ha-1 yr-1), mainly resulting from lower EC-estimated Re; 10% lower ecosystem respiration (Re, 1.39Mg C ha-1 yr-1); and 3% lower gross primary production (0.48 Mg C ha-1 yr-1) The discrepancies between EC and the other methods were higher at sites with complex topography and dense canopies versus those with flat topography and open canopies. Forest age also influenced the discrepancy through the change of leaf area index. The open-path EC system induced >50% of the discrepancy in NEP, presumably due to its surface heating effect. These results provided strong evidence that EC produces biased estimates of NEP and Re in forest ecosystems. A global extrapolation suggested that the discrepancies in CO 2 fluxes between methods were consistent with a global underestimation of Re, and overestimation of NEP, by the EC method. Accounting for these discrepancies would substantially improve the our estimates of the terrestrial carbon budget .

Wang, Xingchang↗
DOE OSTI2015

Fall Prevention in Community Settings: Results from Implementing Stepping On in Three States

Stepping On is a community-based intervention that has been shown in a randomized controlled trial to reduce fall risk. The Wisconsin Institute for Healthy Aging adapted Stepping On for use in the United States and developed a training infrastructure to enable dissemination. The purpose of this study is to: (1) describe the personal characteristics of Stepping On participants; (2) quantify participants’ functional and self-reported health status at enrollment, and (3) measure changes in participants’ functional and self-reported health status after completing the program. Both survey and observed functional status [timed up and go (TUG) test] data were collected between September 2011 and December 2013 for 366 participants enrolled in 32 Stepping On programs delivered in Colorado, New York, and Oregon. Paired t-tests and general estimating equations models adjusted for socio-demographic factors were performed to assess changes over the program period. Among the 266 participants with pre–post survey data, the average participant age was 78.7 (SD ± 8.0) years. Most participants were female (83.4%), white (96.9%), and in good health (49.4%). The TUG test scores decreased significantly (p < 0.001) for all 254 participants with pre–post data. The change was most noticeable among high risk participants where TUG time decreased from 17.6 to 14.4 s. The adjusted odds ratio of feeling confident about keeping from falling was more than three times greater after completing Stepping On. Further, the adjusted odds ratios of reporting “no difficulty” for getting out of a straight back chair increased by 89%. Intended for older adults who have fallen in the past or are afraid of falling, Stepping On has the potential to reduce the frequency and burden of older adult falls.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Body Mass Index at Accession and Incident Cardiometabolic Risk Factors in US Army Soldiers, 2001–2011

Individuals entering US Army service are generally young and healthy, but many are overweight, which may impact cardiometabolic risk despite physical activity and fitness requirements. This analysis examines the association between Soldiers’ BMI at accession and incident cardiometabolic risk factors (CRF) using longitudinal data from 731,014 Soldiers (17.0% female; age: 21.6 [3.9] years; BMI: 24.7 [3.8] kg/m 2 ) who were assessed at Army accession, 2001–2011. CRF were defined as incident diagnoses through 2011, by ICD-9 code, of metabolic syndrome, glucose/insulin disorder, hypertension, dyslipidemia, or overweight/obesity (in those not initially overweight/obese). Multivariable-adjusted proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) between BMI categories at accession and CRF. Initially underweight (BMI<18.5 kg/m 2 ) were 2.4% of Soldiers, 53.5% were normal weight (18.5-<25), 34.2% were overweight (25-<30), and 10.0% were obese (≥30). Mean age range at CRF diagnosis was 24–29 years old, with generally low CRF incidence: 228 with metabolic syndrome, 3,880 with a glucose/insulin disorder, 26,373 with hypertension, and 13,404 with dyslipidemia. Of the Soldiers who were not overweight or obese at accession, 5,361 were eventually diagnosed as overweight or obese. Relative to Soldiers who were normal weight at accession, those who were overweight or obese, respectively, had significantly higher risk of developing each CRF after multivariable adjustment (HR [95% CI]: metabolic syndrome: 4.13 [2.87–5.94], 13.36 [9.00–19.83]; glucose/insulin disorder: 1.39 [1.30–1.50], 2.76 [2.52–3.04]; hypertension: 1.85 [1.80–1.90], 3.31 [3.20–3.42]; dyslipidemia: 1.81 [1.75–1.89], 3.19 [3.04–3.35]). Risk of hypertension, dyslipidemia, and overweight/obesity in initially underweight Soldiers was 40%, 31%, and 79% lower, respectively, versus normal-weight Soldiers. BMI in early adulthood has important implications for cardiometabolic health, even within young, physically active populations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Low serum zinc is associated with elevated risk of cadmium nephrotoxicity

Background: Despite animal evidence suggests that zinc modulates cadmium nephrotoxicity, limited human data are available. Objective: To test the hypothesis that low serum zinc concentrations may increase the risk of cadmium-mediated renal dysfunction in humans. Methods: Data from 1545 subjects aged 20 or older in the National Health and Nutrition Examination Survey (NHANES), 2011–2012 were analyzed. Renal function was defined as impaired when estimated glomerular filtration rate (eGFR) fell below 60 ml/min/1.73 m{sup 2} and/or the urinary albumin-to-creatinine ratio surpassed 2.5 in men and 3.5 mg/mmol in women. Results: Within the study cohort, 117 subjects had reduced eGFR and 214 had elevated urinary albumin. After adjusting for potential confounders, subjects with elevated blood cadmium (>0.53 μg/L) were more likely to have a reduced eGFR (odds ratio [OR]=2.21, 95% confidence interval [CI]: 1.09–4.50) and a higher urinary albumin (OR=2.04, 95% CI: 1.13–3.69) than their low cadmium (<0.18 μg/L) peers. In addition, for any given cadmium exposure, low serum zinc is associated with elevated risk of reduced eGFR (OR=3.38, 95% CI: 1.39–8.28). A similar increase in the odds ratio was observed between declining serum zinc and albuminuria but failed to reach statistical significance. Those with lower serum zinc/blood cadmium ratios were likewise at a greater risk of renal dysfunction (p<0.01). Conclusions: This study results suggest that low serum zinc concentrations are associated with an increased risk of cadmium nephrotoxicity. Elevated cadmium exposure is global public health issue and the assessment of zinc nutritional status may be an important covariate in determining its effective renal toxicity. - Highlights: • Blood cadmium was associated with increased risk of nephrotoxicity. • Low serum zinc may exacerbate risk of cadmium-mediated renal dysfunction. • Both zinc deficiency and elevated cadmium exposure are global public health issues. • Nutritional status is important in the assessment of cadmium nephrotoxicity.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

The Position Index of Overhead LED Sources Under Different Spectral Power Distributions and Background Luminances

The position index was developed by Luckiesh and Guth in 1949 and is widely used in discomfort glare models to account for the position of the glare source when predicting the presence and magnitude of visual discomfort. The applicability of this index to modern LED sources has not been evaluated; however, it is of concern due to potentially higher luminance levels of LEDs compared to the sources used by Luckiesh and Guth. Furthermore, the position index of overhead sources beyond 60° above the line of sight has not been quantified. An experiment was conducted using a hemispherical apparatus with LED sources. The position of the light source, background luminance, the spectral power distribution, and anchor (starting luminance level before adjustment) were varied and two procedures were used to determine the position index of these sources. Data from 29 participants indicate that overhead sources located 60° or 80° above the line of sight were detectable and their position index can be quantified. The position index values were found to be higher than those reported in previous studies, suggesting that anchor bias and the small luminance range in previous studies likely influenced their position index values. No differences were found in position index values by spectral power distribution, background luminance, participant age group, or eyeglass wearing. In conclusion, the position index values reported in this study account for range and anchor bias, providing a better estimate that should be incorporated into discomfort glare models.

Discomfort glare↗
DOE OSTI2014

A first-look atmospheric modeling study of the young directly imaged planet-mass companion, ROXS 42Bb

We present and analyze JK{sub s}L' photometry and our previously published H-band photometry and K-band spectroscopy for ROXs 42Bb, an object Currie et al. first reported as a young directly imaged planet-mass companion. ROXs 42Bb exhibits IR colors redder than field L dwarfs but consistent with other planet-mass companions. From the H{sub 2}O-2 spectral index, we estimate a spectral type of L0 ± 1; weak detections/non-detections of the CO bandheads, Na I, and Ca I support evidence for a young, low surface gravity object primarily derived from the H{sub 2}(K) index. ROXs 42Bb's photometry/K-band spectrum are inconsistent with limiting cases of dust-free atmospheres (COND) and marginally inconsistent with the AMES/DUSTY models and the BT-SETTL models. However, ROXS 42Bb data are simultaneously fit by atmosphere models incorporating several micron-sized dust grains entrained in thick clouds, although further modifications are needed to better reproduce the K-band spectral shape. ROXs 42Bb's best-estimated temperature is T {sub eff} ∼ 1950-2000 K, near the low end of the empirically derived range in Currie et al. For an age of ∼1-3 Myr and considering the lifetime of the protostar phase, ROXs 42Bb's luminosity of log(L/L {sub ☉}) ∼ –3.07 ± 0.07 implies a mass of 9{sub −3}{sup +3} M{sub J} , making it one of the lightest planetary-mass objects yet imaged.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Emergency department visits in California associated with wildfire PM 2.5 : differing risk across individuals and communities

The threats to human health from wildfires and wildfire smoke (WFS) in the United States (US) are increasing due to continued climate change. A growing body of literature has documented important adverse health effects of WFS exposure, but there is insufficient evidence regarding how risk related to WFS exposure varies across individual or community level characteristics. To address this evidence gap, we utilized a large nationwide database of healthcare utilization claims for emergency department (ED) visits in California across multiple wildfire seasons (May through November, 2012–2019) and quantified the health impacts of fine particulate matter <2.5 μm (PM 2.5 ) air pollution attributable to WFS, overall and among subgroups of the population. We aggregated daily counts of ED visits to the level of the Zip Code Tabulation Area (ZCTA) and used a time-stratified case-crossover design and distributed lag non-linear models to estimate the association between WFS and relative risk of ED visits. We further assessed how the association with WFS varied across subgroups defined by age, race, social vulnerability, and residential air conditioning (AC) prevalence. Over a 7 day period, PM 2.5 from WFS was associated with elevated risk of ED visits for all causes (1.04% (0.32%, 1.71%)), non-accidental causes (2.93% (2.16%, 3.70%)), and respiratory disease (15.17% (12.86%, 17.52%)), but not with ED visits for cardiovascular diseases (1.06% (–1.88%, 4.08%)). Analysis across subgroups revealed potential differences in susceptibility by age, race, and AC prevalence, but not across subgroups defined by ZCTA-level Social Vulnerability Index scores. These results suggest that PM 2.5 from WFS is associated with higher rates of all cause, non-accidental, and respiratory ED visits with important heterogeneity across certain subgroups. Notably, lower availability of residential AC was associated with higher health risks related to wildfire activity.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Radiation Effects on Mortality from Solid Cancers Other than Lung, Liver, and Bone Cancer in the Mayak Worker Cohort: 1948–2008

Radiation effects on mortality from solid cancers other than lung, liver, and bone cancer in the Mayak worker cohort: 1948–2008. The cohort of Mayak Production Association (PA) workers in Russia offers a unique opportunity to study the effects of prolonged low dose rate external gamma exposures and exposure to plutonium in a working age population. We examined radiation effects on the risk of mortality from solid cancers excluding sites of primary plutonium deposition (lung, liver, and bone surface) among 25,757 workers who were first employed in 1948–1982. During the period 1948–2008, there were 1,825 deaths from cancers other than lung, liver and bone. Using colon dose as a representative external dose, a linear dose response model described the data well. The excess relative risk per Gray for external gamma exposure was 0.16 (95% CI: 0.07 – 0.26) when unadjusted for plutonium exposure and 0.12 (95% CI 0.03 – 0.21) when adjusted for plutonium dose and monitoring status. There was no significant effect modification by sex or attained age. Plutonium exposure was not significantly associated with the group of cancers analyzed after adjusting for monitoring status. Site-specific risks were uncertainly estimated but positive for 13 of the 15 sites evaluated with a statistically significant estimate only for esophageal cancer. Comparison with estimates based on the acute exposures in atomic bomb survivors suggests that the excess relative risk per Gray for prolonged external exposure in Mayak workers may be lower than that for acute exposure but, given the uncertainties, the possibility of equal effects cannot be dismissed.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

The first brown dwarf/planetary-mass object in the 32 Orionis group

The 32 Orionis group is a co-moving group of roughly 20 young (24 Myr) M3-B5 stars 100 pc from the Sun. Here we report the discovery of its first substellar member, WISE J052857.69+090104.2. This source was previously reported to be an M giant star based on its unusual near-infrared spectrum and lack of measureable proper motion. We re-analyze previous data and new moderate-resolution spectroscopy from Magellan/Folded-port InfraRed Echellette to demonstrate that this source is a young near-infrared L1 brown dwarf with very low surface gravity features. Spectral model fits indicate T{sub eff} = 1880{sub −70}{sup +150} K and logg = 3.8{sub −0.2}{sup +0.2}, consistent with a 15–22 Myr object with a mass near the deuterium-burning limit. Its sky position, estimated distance, kinematics (both proper motion and radial velocity), and spectral characteristics are all consistent with membership in 32 Orionis, and its temperature and age imply a mass (M = 14{sub −3}{sup +4} M{sub J}) that straddles the brown dwarf/planetary-mass object boundary. The source has a somewhat red J−W2 color compared to other L1 dwarfs, but this is likely a low-gravity-related temperature offset; we find no evidence of significant excess reddening from a disk or cool companion in the 3–5 μm waveband.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Late Holocene glacier and climate fluctuations in the Mackenzie and Selwyn mountain ranges, northwestern Canada

Over the last century, northwestern Canada experienced some of the highest rates of tropospheric warming globally, which caused glaciers in the region to rapidly retreat. Our study seeks to extend the record of glacier fluctuations and assess climate drivers prior to the instrumental record in the Mackenzie and Selwyn mountains of northwestern Canada. We collected 27 10 Be surface exposure ages across nine cirque and valley glacier moraines to constrain the timing of their emplacement. Cirque and valley glaciers in this region reached their greatest Holocene extents in the latter half of the Little Ice Age (1600–1850 CE). Four erratic boulders, 10–250 m distal from late Holocene moraines, yielded 10 Be exposure ages of 10.9–11.6 ka, demonstrating that by ca. 11 ka, alpine glaciers were no more extensive than during the last several hundred years. Estimated temperature change obtained through reconstruction of equilibrium line altitudes shows that since ca. 1850 CE, mean annual temperatures have risen 0.2–2.3 °C. We use our glacier chronology and the Open Global Glacier Model (OGGM) to estimate that from 1000 CE, glaciers in this region reached a maximum total volume of 34–38 km 3 between 1765 and 1855 CE and had lost nearly half their ice volume by 2019 CE. OGGM was unable to produce modeled glacier lengths that match the timing or magnitude of the maximum glacier extent indicated by the 10 Be chronology. However, when applied to the entire Mackenzie and Selwyn mountain region, past millennium OGGM simulations using the Max Planck Institute Earth System Model (MPI-ESM) and the Community Climate System Model 4 (CCSM4) yield late Holocene glacier volume change temporally consistent with our moraine and remote sensing record, while the Meteorological Research Institute Earth System Model 2 (MRI-ESM2) and the Model for Interdisciplinary Research on Climate (MIROC) fail to produce modeled glacier change consistent with our glacier chronology. Finally, OGGM forced by future climate projections under varying greenhouse gas emission scenarios predicts 85 % to over 97 % glacier volume loss by the end of the 21st century. The loss of glaciers from this region will have profound impacts on local ecosystems and communities that rely on meltwater from glacierized catchments.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1972

Metal-poor stars. IV - The evolution of red giants.

Detailed evolutionary calculations for six Population-II red giants are presented. The first five of these models are followed from the zero age main sequence to the onset of the helium flash. The sixth model allows the effect of direct electron-neutrino interactions to be estimated. The updated input physics and evolutionary code are described briefly. The results of the calculations are presented in a manner pertinent to later stages of evolutions and suitable for comparison with observations.

Rood, R. T.↗
NASA NTRS1982

On isostasy at Atlantic-type continental margins

The concept of isostasy describes the manner in which topographic features on the earth's surface are compensated at depth. The present investigation is concerned with the isostatic mechanism at Atlantic-type continental margins. Particular attention is given to the question whether the flexure model of isostasy, which has successfully been used at other geological features in oceans, is applicable at margins. Cross-spectral techniques are used to analyze the relationship between free air gravity and topography at Atlantic-type continental margins. The relatively old eastern North America is found to be associated with the highest value of the effective elastic thickness in the range 10-20 km, while the relatively young Coral Sea/Lord Howe rise is associated with the lowest value of less than 5 km. The differences in estimates of effective elastic thickness between margins can be explained by a simple model in which the flexural strength of the basement increases with age.

Karner, G. D.↗
NASA NTRS1982

The negative gravity field over the 85 deg E ridge

Two north-south ridges in the basement topography of the Bay of Bengal may be observed on an isopach map at 85 and at 90 deg E. Free-air gravity anomaly profiles across the region show a strong gravity low (about -60 mGal) over the 85 deg E ridge, and a gravity high over the other. Using a simple two-stage loading model, the negative gravity anomaly over the 85 deg E ridge is explained as a direct consequence of sediment loading, and the flexural rigidity of the lithosphere when the ridge was formed is estimated to have been about 180 times less than the flexural rigidity during the sediment loading. An approximate relationship between flexural rigidity and crustal age shows that the 85 deg E ridge was formed on relatively young lithosphere, 5-15 million years old, and that it was buried when the lithosphere was 40-80 million years old. The alteration of the gravity field by a thick layer of sediments may occur in other large sedimentary basins or along continental margins.

Liu, C.-S.↗
NASA NTRS1988

Metamorphic P-T paths and Precambrian crustal growth in East Antarctica

The metamorphic constraints on crustal thicknesses in Archean and post-Archean terranes are summarized along with possible implications for tectonic processes. It is important to recognize that P-T estimates represent perturbed conditions and should not be used to estimate steady state geothermal gradients or crustal thicknesses. The example is cited of the Dora Maira complex in the French Alps, where crustal rocks record conditions of 35 kbar and 800 C, implying their subduction to depths of 100 km or more, followed by subsequent uplift to the surface. Therefore such P-T estimates tell more about processes than crustal thicknesses. More importantly, according to the author, are determinations of P-T paths, particularly coupled with age measurements, because these may provide constraints on how and when perturbed conditions relax back to steady state conditions. P-T paths are illustrated that should be expected from specific tectonic processes, including Tibetan style collision, with and without subsequent extension, rifting of thin or thickened crust, and magmatic accretion. Growth of new crust, associated with magmatic accretion, for example, could possibly be monitored with these P-T paths.

Harley, S. L.↗
NASA NTRS1994

An X-ray study of five supernova remnants in the Carina spiral arm

The ROSAT Position Sensitive Proportional Counter (PSPC) is used to perform an exploratory study of four fields in the Carina spiral arm containing five radio supernova remnants, only one of which has previously been studied in X-rays. We present upper limits for the detection in X-rays of G298.5 - 0.3, G298.6 - 0.0, and G299.0+0.2, and report a 4 sigma detection of G296.8-0.3. In addition, we present detailed spatial and spectral analysis of the bright X-ray remnant G296.1-0.7, which has previously been studied by both the Einstein IPC and EXOSAT LE/CMA. We detect relatively slight, but statistically significant, variations in the spectrum across the remnant via spatially resolved spectral fits and a study of the spatial variation of hardness ratios. In general, the spectrum is characteristic of a thermal plasma with kT about 0.2 keV and N(sub H) about 1.5 x 10(exp 21/sq. cm). The total X-ray emitting mass is estimated to be about 250 solar mass for an optically estimated distance of 4 kpc to the remnant. At this distance, the linear dimensions of the remnant are roughly 35 - 50 pc, implying an age on the order of 20,000 yr. Assuming that X-ray and radio brightnesses are related by SIGMA(sub R) proportional to SIGMA(exp 0.69)(sub X) and that the four radio remnants have X-ray spectral characteristics similar to G296.1-0.7, we find that the column densities to these sources must be several times 10(exp 22)/sq cm in order to explain their low X-ray count rates. This column density is considerably in excess of the X-ray fitted column density to G296.1-0.7, but is comparable to the total column densities in H I measured via the 21 cm line in the directions to all five remnants. This implies that G296.1 - 0.7 is at a significantly smaller distance than the other remnants.

Hwang, Una↗
NASA NTRS2010

Decline in Aerobic Fitness After Long-Term Stays on the International Space Station

U.S. and non-Russian International Partner astronauts who participate in long-term International Space Station (ISS) expeditions perform submaximal cycle exercise tests before, during, and after space flight. The heart rate (HR) and oxygen uptake (VO2) responses to exercise are used to estimate peak VO2 (EVO2pk). Purpose: To determine if the following factors are associated with the preflight-to-post flight change in EVO2pk: gender, age, body weight (BW), number of aerobic exercise sessions/wk- during flight, length of flight, EVO2pk measured before and late during the flight, ISS Expedition number and time between landing and the first post flight test. Methods: Records of 37 ISS astronauts (30 male, BW=81.6 plus or minus 8.6 kg; 7 female BW=66.1 plus or minus 4.9 kg [mean plus or minus SD]), age 46 plus or minus 4 years, were retrospectively examined. Peak HR and VO2 were measured approximately 9 months before flight to establish the test protocol. The submaximal cycle test consisted of three 5-minute stages designed to elicit 25, 50, and 75% of VO2pk. EVO2pk was calculated using linear least-squares extrapolation of average HR and VO2 during the last minute of each stage to predict VO2 at maximal HR. VO2 was not measured during flight and was assumed to not be different from preflight. Testing was performed 45 days before launch, late during flight, and during the week after landing. A random-intercept multivariate model was used to determine which characteristics significantly contributed to post flight EVO2pk. Results: In-flight aerobic exercise averaged 5.4 plus or minus 1.2 sessions/wk. ISS flight duration averaged 163 plus or minus 39 d. Mean EVO2pk values were 3.41 plus or minus 0.64 L (raised dot) per minute before flight, 3.09 plus or minus 0.57 L (raised dot) per minute late in flight, and 3.02 plus or minus 0.65 L (raised dot) per minute after flight. Late- and after-flight values were lower (p less than 0.05) than preflight values and did not differ from each other. Time between landing and post flight testing was 4.5 plus or minus 1.6 days. The only factor significantly associated with the post flight EVO2pk value was the late-flight EVO2pk score. Conclusion: Testing performed late during a mission provides a prediction of EVO2pk after landing. This approach may be implemented during longer missions.

Lynn, Peggy A.↗
NASA NTRS2013

Direct Imaging Discovery of A Super-Jupiter Around the Late B-Type Star K And*

We present the direct imaging discovery of an extrasolar planet, or possible low-mass brown dwarf, at a projected separation of 55 plus or minus 2 AU (1."058 plus or minus 0."007) from the B9-type star K And. The planet was detected with Subaru/HiCIAO (Subaru/High Contrast Instrument for the Subaru Next Generation Adaptive Optics) during the SEEDS (Strategic Exploration of Exoplanets and Disks with Subaru Telescope/HiCIAO) survey and confirmed as a bound companion via common proper motion measurements. Observed near-infrared magnitudes of J equals 16.3 plus or minus 0.3, H equals 15.2 plus or minus 0.2, K (sub s) = 14.6 plus or minus 0.4, and L prime equals 13.12 plus or minus 0.09 indicate a temperature of approximately 1700 degrees Kelvin. The galactic kinematics of the host star are consistent with membership in the Columba Association, implying a corresponding age of 30 (exp from plus 20 to minus10) Myr. The systems age, combined with the companion photometry, points to a model-dependent companion mass approximately 12.8 times the mass of Jupiter. The host stars estimated mass of 2.4 to 2.5 times the mass of the sun places it among the most massive stars ever known to harbor an extrasolar planet or low-mass brown dwarf. While the mass of the companion is close to the deuterium burning limit, its mass ratio, orbital separation, and likely planet-like formation scenario imply that it may be best defined as a super-Jupiter with properties similar to other recently discovered companions to massive stars.

HiCIAO↗
DOE OSTI2017

Concrete structural health monitoring in nuclear power plants - 212

Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Health monitoring of concrete structures is performed in order to understand the current condition of a structure based on heterogeneous measurements and produce high-confidence actionable information regarding structural integrity. This information can be used to support operational and maintenance decisions. This paper describes a framework of research activities for health monitoring of nuclear power plant concrete structures. The proposed framework consists of four elements: (1) health monitoring, (2) data analytics, (3) uncertainty quantification, and (4) prognosis. The goal of this framework is to enable plant operators to make risk-informed decisions about structural integrity, remaining useful life, and performance of concrete structures across the nuclear fleet. Among several concrete degradations, research focuses on degradation caused by the alkali-silica reaction (ASR). ASR is a chemical reaction that, in the presence of sufficient moisture, forms a gel that increases in volume and exerts an expansive pressure inside the material, thus causing micro to macro-cracks. This paper also presents development of controlled concrete samples with reactive aggregates to cause ASR degradation and application of different non-destructive evaluation techniques to detect the damage caused by ASR. Initial results are presented in the paper along with a potential path forward. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗