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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.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Extragalactic millimeter-wave point-source catalog, number counts and statistics from 771 deg{sup 2} of the SPT-SZ survey

We present a point-source catalog from 771 deg{sup 2} of the South Pole Telescope Sunyaev-Zel'dovich survey at 95, 150, and 220 GHz. We detect 1545 sources above 4.5σ significance in at least one band. Based on their relative brightness between survey bands, we classify the sources into two populations, one dominated by synchrotron emission from active galactic nuclei, and one dominated by thermal emission from dust-enshrouded star-forming galaxies. We find 1238 synchrotron and 307 dusty sources. We cross-match all sources against external catalogs and find 189 unidentified synchrotron sources and 189 unidentified dusty sources. The dusty sources without counterparts are good candidates for high-redshift, strongly lensed submillimeter galaxies. We derive number counts for each population from 1 Jy down to roughly 11, 4, and 11 mJy at 95, 150, and 220 GHz. We compare these counts with galaxy population models and find that none of the models we consider for either population provide a good fit to the measured counts in all three bands. The disparities imply that these measurements will be an important input to the next generation of millimeter-wave extragalactic source population models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Linear fitting of multi-threshold counting data

The present disclosure provides a system and method for efficiently mining multi-threshold measurements acquired using photon counting pixel-array detectors for spectral imaging and diffraction analyses. Images of X-ray intensity as a function of X-ray energy were recorded on a 6 megapixel X-ray photon counting array detector through linear fitting of the measured counts recorded as a function of counting threshold. An analytical model is disclosed for describing the probability density of detected voltage, utilizing fractional photon counting to account for edge/corner effects from voltage plumes that spread across multiple pixels. Three-parameter fits to the model were independently performed for each pixel in the array for X-ray scattering images acquired for 13.5 keV and 15.0 keV X-ray energies. From the established pixel responses, multi-threshold composite images produced from the sum of 13.5 keV and 15.0 keV data can be analytically separated to recover the monochromatic images through simple linear fitting.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Expression of a mammalian RNA demethylase increases flower number and floral stem branching in Arabidopsis thaliana

Abstract RNA methylation plays a central regulatory role in plant biology and is a relatively new target for plant improvement efforts. In nearly all cases, perturbation of the RNA methylation machinery results in deleterious phenotypes. However, a recent landmark paper reported that transcriptome‐wide use of the human RNA demethylase FTO substantially increased the yield of rice and potatoes. Here, we have performed the first independent replication of those results and demonstrated broader transferability of the trait, finding increased flower and fruit count in the model species Arabidopsis thaliana . We also performed RNA‐seq of our FTO‐transgenic plants, which we analyzed in conjunction with previously published datasets to detect several previously unrecognized patterns in the functional and structural classification of the upregulated and downregulated genes. From these, we present mechanistic hypotheses to explain these surprising results with the goal of spurring more widespread interest in this promising new approach to plant engineering.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Anatomy of deconfinement

In the weak coupling limit of ${\rm SU}(N)$ Yang-Mills theory and the ${\rm O}(N)$ vector model, explicit state counting allows us to demonstrate the existence of a partially deconfined phase: $M$ of $N$ colors deconfine, and $\frac{M}{N}$ gradually grows from zero (confinement) to one (complete deconfinement). We point out that the mechanism admits a simple interpretation in the form of spontaneous breaking of gauge symmetry. In terms of the dual gravity theory, such breaking occurs during the formation of a black hole. We speculate whether the breaking and restoration of gauge symmetry can serve as an alternative definition of the deconfinement transition in theories without center symmetry, such as QCD. We also discuss the role of the color degrees of freedom in the emergence of the bulk geometry in holographic duality.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Seasonal Disorder in Urban Traffic Patterns: A Low Rank Analysis

This article proposes several advances to sparse nonnegative matrix factorization (SNMF) as a way to identify large-scale patterns in urban traffic data. The input to our model is traffic counts organized by time and location. Nonnegative matrix factorization additively decomposes this information, organized as a matrix, into a linear sum of temporal signatures. Penalty terms encourage this factorization to concentrate on only a few temporal signatures, with weights which are not too large. Our interest here is to quantify and compare the regularity of traffic behavior, particularly across different broad temporal windows. In addition to the rank and error, we adapt a measure introduced by Hoyer to quantify sparsity in the representation. Combining these, we construct several curves which quantify error as a function of rank (the number of possible signatures) and sparsity; as rank goes up and sparsity goes down, the approximation can be better and the error should decreases. Plots of several such curves corresponding to different time windows leads to a way to compare disorder/order at different time scalewindows. In this paper, we apply our algorithms and procedures to study a taxi traffic dataset from New York City. In this dataset, we find weekly periodicity in the signatures, which allows us an extra framework for identifying outliers as significant deviations from weekly medians. We then apply our seasonal disorder analysis to the New York City traffic data and seasonal (spring, summer, winter, fall) time windows. We do find seasonal differences in traffic order.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2026

Leveraging 13C-Labeling to Assign Molecular Formulas to Unknown Yeast Metabolites

Mass spectrometry analyses have identified tens of thousands of unknown small molecule-associated peaks in different biological specimens. Notably, even the simplest and best studied organisms like Escherichia coli and Saccharomyces cerevisiae yield thousands of unknown peaks. A key question is how many of these reflect actual novel endogenous metabolites. To explore this, Mahieu and Patti used complete 13 C -labeling in E. coli to credential peaks as biological. This reduced the number of unknowns by more than 90%. Here, we carry out similar uniform 13 C-labeling in the Baker’s yeast S. cerevisiae and two less-studied bioenergy-relevant yeasts Rhodotorula toruloides (lipid producer) and Issatchenkia orientalis (organic acid producer). Identification of unknown metabolite peaks and their molecular formulas is facilitated through software tailored for 13 C labeling data and resulting knowledge of carbon atom count. A classification model evaluates the plausibility of each candidate formula, with peaks lacking plausible candidate formulas unlikely to reflect metabolite molecular ions. This approach prioritizes about one hundred candidate abundant unknown metabolites with logical molecular formulas. Most of these are species-specific rather than conserved across yeasts, and more are found in the nonmodel yeasts than S. cerevisiae. Thus, 13 C-labeling data on unknown metabolites highlights the potential for discovering new metabolites and pathways in nonmodel yeasts.

Carbon↗
DOE OSTI2025

LandScan Global 30 Arcsecond Annual Global Gridded Population Datasets from 2000 to 2022

Abstract Oak Ridge National Laboratory (ORNL) annually develops the LandScan Global (LSG) dataset, a 30 arcsecond global gridded population dataset representing global ambient human population distribution. This multivariable dasymetric model disaggregates census counts within administrative boundaries using ancillary data. Each country’s distribution reflects cultural and socioeconomic patterns; manual validations yield a unique global dataset for assessing populations at risk. For over two decades, LSG has been a standard for estimating populations at risk, aiding U.S. federal government, academia and humanitarian organizations. During disasters such as the 2004 Indian Ocean tsunami and the 2010 Haiti earthquake and geopolitical crises such as the Syrian civil war and the 2022 Russian invasion of Ukraine, LSG supported scientific and operational communities in emergency response and recovery. In 2022, LSG datasets from 2000 onward were made publicly available through ORNL’s LandScan Portal. This data descriptor details our methodology and the application of geospatial science and machine learning to geographic and demographic data, highlighting uses in urban resiliency, emergency management, disaster response, and human health and security.

Science & Technology - Other Topics↗
DOE OSTI2012

Metallicity of InN and GaN surfaces exposed to NH{sub 3}.

A systematic study of energies and structures of InN and GaN (0001) surfaces exposed to NH{sub 3} and its decomposition products was performed with first-principles methods. A phenomenological model including electron counting contributions is developed based on calculated DFT energies and is used to identify low-energy structures. These predictions are checked with additional DFT calculations. The equilibrium phase diagrams are found to contain structures that violate the electron counting rule. Densities of states for these structures indicate n-type conductivity, consistent with available experimental results.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

On the effect of Ga and In substitutions in the Ca 11 Bi 10 and Yb 11 Bi 10 bismuthides crystallizing in the tetragonal Ho 11 Ge 10 structure type

The Ga- and In-substituted bismuthides Ca 11 Ga x Bi 10– x , Ca 11 In x Bi 10– x , Yb 11 Ga x Bi 10– x , and Yb 11 In x Bi 10– x ( x < 2) can be readily synthesized employing molten Ga or In metals as fluxes. They crystallize in the tetragonal space group I 4/ mmm and adopt the Ho 11 Ge 10 structure type (Pearson code tI 84; Wyckoff sequence n 2 m j h 2 e 2 d ). The structural response to the substitution of Bi with smaller and electron-poorer In or Ga has been studied by single-crystal X-ray diffraction methods for the case of Ca 11 In x Bi 10– x [ x = 1.73 (2); octabismuth undecacalcium diindium]. The refinements show that the In atoms substitute Bi only at the 8 h site. The refined interatomic distances show an unconventional – for this structure type – bond-length distribution within the anionic sublattice. The latter can be viewed as consisting of isolated Bi 3- anions and [In 4 Bi 8 20- ] clusters for the idealized Ca 11 In 2 Bi 8 model. Formal electron counting and first-principle calculations show that the peculiar bonding in this compound drives the system toward an electron-precise state, thereby stabilizing the observed bond-length pattern.

Chemistry↗
DOE OSTI2024

Analysis of prescribed fire days in climate model output

This code analyzes openly available, downscaled climate model output and counts days in a year that are available to conduct prescribed fire based on meteorological prescription data obtained from US land management agencies.

Jonko, Alexandra↗
DOE OSTI2017

Galaxy and Mass Assembly (GAMA): Exploring the WISE Web in G12

We present an analysis of the mid-infrared Wide-field Infrared Survey Explorer (WISE) sources seen within the equatorial GAMA G12 field, located in the North Galactic Cap. Our motivation is to study and characterize the behavior of WISE source populations in anticipation of the deep multiwavelength surveys that will define the next decade, with the principal science goal of mapping the 3D large-scale structures and determining the global physical attributes of the host galaxies. In combination with cosmological redshifts, we identify galaxies from their WISE W1 (3.4 μm) resolved emission, and we also perform a star-galaxy separation using apparent magnitude, colors, and statistical modeling of star counts. The resulting galaxy catalog has ≃590,000 sources in 60 deg{sup 2}, reaching a W1 5σ depth of 31 μJy. At the faint end, where redshifts are not available, we employ a luminosity function analysis to show that approximately 27% of all WISE extragalactic sources to a limit of 17.5 mag (31 μJy) are at high redshift, z>1. The spatial distribution is investigated using two-point correlation functions and a 3D source density characterization at 5 Mpc and 20 Mpc scales. For angular distributions, we find that brighter and more massive sources are strongly clustered relative to fainter sources with lower mass; likewise, based on WISE colors, spheroidal galaxies have the strongest clustering, while late-type disk galaxies have the lowest clustering amplitudes. In three dimensions, we find a number of distinct groupings, often bridged by filaments and superstructures. Using special visualization tools, we map these structures, exploring how clustering may play a role with stellar mass and galaxy type.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Results of Robotic Evaluation of Uranium-235 in Gaseous Diffusion Piping Holdup Deposits - 18303

Measurement of U-235 in pipes within old uranium enrichment facilities is time-consuming and very costly. Radiometric assay from outside the pipes suffers from manual deployment challenges, attenuation of detection through pipe walls, long counting times, approximate modeling, and shortfalls associated with transcription and human interpretation. The D and D process of cutting into these pipes creates a unique possibility of robotic in-pipe assay to address these problems. This paper presents the results of testing a first-of-kind radiometric non-destructive assay (NDA) robot for high-cadence, accurate, certain, paperless assay of U-235 in holdup deposits within process piping. The robot's enabling capability is an innovative radiometric collimation method that views only a one-foot moving annulus of pipe wall. This exploits the internal axisymmetry of pipes to provide a direct measurement of industry-standard grams per foot U-235. The initial proof-of-application robot was successfully hot tested by operators at the Gaseous Diffusion Enrichment Facility in Piketon, Ohio, in late 2017. This testing achieved all goals of traversing pipe, measuring U-235, deployment by facility personnel, and displaying analyzed radiation, visual, and geometric information. The success was a Kitty Hawk moment. The system demonstrated robotic in-pipe measurement of holdup deposit to a resolution, accuracy, and speed unachievable by alternate methods. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Robotic NDA of Holdup Deposits in Gaseous Diffusion Piping by Gamma Assay of Uranium-235 - 18331

This research exploits in-pipe access to develop robotically deployed, high-cadence, accurate, certain, paperless assay of U-235 in holdup deposits within process piping. Prior radiometric assay from outside the pipes suffered from manual deployment challenges, attenuation of detection through pipe walls, long counting times, approximate modeling, and shortfalls associated with transcription and human interpretation. These downsides limited the speed, quality, and economy of assay resulting in vast cost and budget consequences to D and D. D and D of outdated facilities cuts into these pipes as part of the demolition process, creating the unique, previously unexploited possibility of robotic in-pipe assay. The assay collimates radiation emanating from all but a short segment of pipe wall from reaching a gamma detector. Hence, the detector only views and measures source from a short segment of pipe at a given time. This is achieved by an innovative pair of collimating discs that are coaxial with the pipe and positioned fore and aft of the detector. The detector assembly is translated through pipes by an autonomous mobile robot. Beyond radiometric assay of U-235, the robot images and geometrically models the pipe interior and deposit appearance. The robot is recovered from the same pipe opening from which it is launched, hence it drives the same distance out and back, measuring the same deposits twice. This achieves redundant radiometric and odometric measurements which adds further to statistical significance of the method. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

A matrix-inversion method for gamma-source mapping from gamma-count data

In a previous paper it was proposed that a simple matrix inversion method could be used to extract source distributions from gamma-count maps, using simple models to calculate the response matrix. The method was tested using numerically generated count maps. In the present work a 100 kBq Co{sup 60} source has been placed on a gridded surface and the count rate measured using a NaI scintillation detector. The resulting map of gamma counts was used as input to the matrix inversion procedure and the source position recovered. A multi-source array was simulated by superposition of several single-source count maps and the source distribution was again recovered using matrix inversion. The measurements were performed for several detector heights. The effects of uncertainties in source-detector distances on the matrix inversion method are also examined. The results from this work give confidence in the application of the method to practical applications, such as the segregation of highly active objects amongst fuel-element debris. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Emulating a System Dynamics Model with Agent-Based Models: A Methodological Case Study in Simulation of Diabetes Progression

An agent-based simulation model hierarchy emulating disease states and behaviors critical to progression of diabetes type 2 was designed and implemented in the DEVS framework. The models are translations of basic elements of an established system dynamics model of diabetes. In this model hierarchy, which mimics diabetes progression over an aggregated U.S. population, was dis-aggregated and reconstructed bottom-up at the individual (agent) level. Four levels of model complexity were defined in order to systematically evaluate which parameters are needed to mimic outputs of the system dynamics model. Moreover, the four estimated models attempted to replicate stock counts representing disease states in the system dynamics model, while estimating impacts of an elderliness factor, obesity factor and health-related behavioral parameters. Health-related behavior was modeled as a simple realization of the Theory of Planned Behavior, a joint function of individual attitude and diffusion of social norms that spread over each agent s social network. Although the most complex agent-based simulation model contained 31 adjustable parameters, all models were considerably less complex than the system dynamics model which required numerous time series inputs to make its predictions. In all three elaborations of the baseline model provided significantly improved fits to the output of the system dynamics model. The performances of the baseline agent-based model and its extensions illustrate a promising approach to translate complex system dynamics models into agent-based model alternatives that are both conceptually simpler and capable of capturing main effects of complex local agent-agent interactions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Investigation of magnetic nanoparticles for the rapid extraction and assay of alpha-emitting radionuclides from urine: Demonstration of a novel radiobioassay method

In the event of an accidental or intentional release of radionuclides into a populated area, three things must occur in a timely manner: food and drinking water supplies must be determined to be safe to eat / drink, civilians and/or military personnel must be surveyed to ensure that they do not have external contamination, and they must be screened to ensure that significant ingestion or inhalation of radionuclides has not occurred (this paper is concerned with the latter). In the event of such a disaster, the volume of radiobioassays to be performed would be tremendous. If the event released significant levels of β- or α-emitting radionuclides, in vivo assays would be ineffective. Therefore, highly efficient and rapid analytical methods for radionuclide detection from submitted spot urine samples (≤ 50 mL) would be required. At present, the quantitative determination of α-emitting radionuclides from urine samples is highly labor intensive, and requires significant sample preparation and analysis time. Sorbent materials that provide effective collection and enable rapid assay could significantly streamline the radioanalytical process. We have demonstrated the use of paramagnetic nanoparticles as a novel class of extracting media for four α-emitting radionuclides of concern (Po, Ra, Am, and U) from chemically unmodified and pH 2 human urine. Herein the initial experimental sorption results are presented along with a novel method that utilizes paramagnetic nanoparticles for the extraction of radionuclides from unmodified human urine followed by the magnetic field-induced collection of the particles for subsequent α-counting-source preparation. Additionally, we construct a versatile human dose model that determines the detector count times required to estimate internal human dose at specific protective action thresholds. The model provides a means to assess a method’s detection capabilities and use fundamental health physics parameters and actual experimental data as core variables. The modeling shows that with effective sorbent materials, rapid screening for internalized α-emitters is possible from a 50 mL spot urine sample volume collected within one week of exposure/intake.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

On the analysis of signal peaks in pulse-height spectra

The estimation of the signal location and intensity of a peak in a pulse height spectrum is important for X- ray and γ-ray spectroscopy, charged-particle spectrometry, liquid chromatography, and many other subfields. However, both the ‘‘centroid’’ and ‘‘signal intensity’’ of a peak in a pulse-height spectrum are ill-defined quantities and different methods of analysis will yield different numerical results. Here, we apply three methods of analysis. Method A is based on simple count summation and is likely the technique most frequently applied in practice. The analysis is straightforward and fast, and does not involve any statistical modeling. We find that it provides reliable results only for high signal-to-noise data, but has severe limitations in all other cases. Method B employs a Bayesian model to extract signal counts and centroid from the measured total and background counts. The resulting values are derived from the respective posteriors and, therefore, have a rigorous statistical meaning. The method makes no assumptions about the peak shape. It yields reliable and relatively small centroid uncertainties. However, it provides relatively large signal count uncertainties. Method C makes a strong assumption regarding the peak shape by fitting a Gaussian function to the data. Furthermore, the fit is based again on a Bayesian model. Although Method C requires careful consideration of the Gaussian width (usually given by the detector resolution) used in the fitting, it provides reliable values and relatively small uncertainties both for the signal counts and the centroid.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

A new G–M counter hybrid dead-time correction model

In this paper, a new G–M counter dead-time model based on the hybrid model is proposed and studied. The new model contains the idealized paralyzable and non-paralyzable dead-time models, but also allows the non-paralyzable dead-time to vary with the true counting rate. To validate this model, the decaying source experiment with a very pure 56 Mn source was used. The calculated true counting rates obtained by fitting the experimental data to the model were compared to the data obtained by table lookup. Finally, in general, the fitting was in good agreement (within 4.8% up to 5.35 × 10 6 counts / minute ) for a G–M counter with a paralyzable dead-time component of 85.9 μs and a non-paralyzable dead-time component ranging from 438 μs to 24.3 ms.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗