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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 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

KECK-I MOSFIRE SPECTROSCOPY OF THE z {approx} 12 CANDIDATE GALAXY UDFj-39546284

We report the results of deep (4.6 hr) H-band spectroscopy of the well studied z {approx} 12 H-band dropout galaxy candidate UDFj-39546284 with MOSFIRE on Keck-I. These data reach a sensitivity of 5-10 Multiplication-Sign 10{sup -19} erg s{sup -1} cm{sup -2} per 4.4 A resolution element between sky lines. Previous papers have argued that this source could either be a large equivalent width line emitting galaxy at 2 < z < 3.5 or a luminous galaxy at z {approx} 12. We find a 2.2{sigma} peak associated with a line candidate in deep Hubble Space Telescope Wide-Field Camera 3 Infrared grism observations, but at a lower flux than expected. After considering several possibilities, we conclude these data cannot conclusively confirm or reject the previous line detection, and significantly deeper spectroscopic observations are required. We also search for low-redshift emission lines in 10 other 7 < z < 10 z, Y, and J-dropout candidates in our mask and find no significant detections.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

DIRECTIONAL DEPENDENCE OF {Lambda}CDM COSMOLOGICAL PARAMETERS

We study hemispherical power asymmetry in the Wilkinson Microwave Anisotropy Probe 9 yr data. We analyze the combined V- and W-band sky maps, after application of the KQ85 mask, and find that the asymmetry is statistically significant at the 3.4{sigma} confidence level for l = 2-600, where the data are signal-dominated, with a preferred asymmetry direction (l, b) = (227, -27). Individual asymmetry axes estimated from six independent multipole ranges are all consistent with this direction. Subsequently, we estimate cosmological parameters on different parts of the sky and show that the parameters A{sub s} , n{sub s} , and {Omega}{sub b} are the most sensitive to this power asymmetry. In particular, for the two opposite hemispheres aligned with the preferred asymmetry axis, we find n{sub s} = 0.959 {+-} 0.022 and n{sub s} = 0.989 {+-} 0.024, respectively.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

DISCOVERY OF Hα EMISSION FROM THE CLOSE COMPANION INSIDE THE GAP OF TRANSITIONAL DISK HD 142527

We utilized the new high-order 585 actuator Magellan Adaptive Optics system (MagAO) to obtain very high-resolution visible light images of HD 142527 with MagAO's VisAO science camera. In the median seeing conditions of the 6.5 m Magellan telescope (0.''5–0.''7), we find MagAO delivers 24%-19% Strehl at Hα (0.656 μm). We detect a faint companion (HD 142527B) embedded in this young transitional disk system at just 86.3 ± 1.9 mas (∼12 AU) from the star. The companion is detected in both Hα and a continuum filter (Δmag = 6.33 ± 0.20 mag at Hα and 7.50 ± 0.25 mag in the continuum filter). This provides confirmation of the tentative companion discovered by Biller and co-workers with sparse aperture masking at the 8 m Very Large Telescope. The Hα emission from the ∼0.25 solar mass companion (EW = 180 Å) implies a mass accretion rate of ∼5.9 × 10{sup –10} M {sub sun} yr{sup –1} and a total accretion luminosity of 1.2% L {sub sun}. Assuming a similar accretion rate, we estimate that a 1 Jupiter mass gas giant could have considerably better (50-1000×) planet/star contrasts at Hα than at the H band (COND models) for a range of optical extinctions (3.4-0 mag). We suggest that ∼0.5-5 M {sub jup} extrasolar planets in their gas accretion phase could be much more luminous at Hα than in the NIR. This is the motivation for our new MagAO GAPplanetS survey for extrasolar planets.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

The impact of adjusting for hysterectomy prevalence on cervical cancer incidence rates and trends among women aged 30 years or older—United States, 2001-2019

Abstract Hysterectomy protects against cervical cancer when the cervix is removed. However, measures of cervical cancer incidence often fail to exclude women with a hysterectomy from the population-at-risk denominator, underestimating and distorting disease burden. In this study, we estimated hysterectomy prevalence from the Behavioral Risk Factor Surveillance System surveys to remove the women who were not at risk of cervical cancer from the denominator and combined these estimates with the US Cancer Statistics data. From these data, we calculated age-specific and age-standardized incidence rates for women aged >30 years from 2001-2019, adjusted for hysterectomy prevalence. We calculated the difference between unadjusted and adjusted incidence rates and examined trends by histology, age, race and ethnicity, and geographic region using joinpoint regression. The hysterectomy-adjusted cervical cancer incidence rate from 2001-2019 was 16.7 per 100 000 women—34.6% higher than the unadjusted rate. After adjustment, incidence rates were higher by approximately 55% among Black women, 56% among those living in the East South Central division, and 90% among women aged 70-79 and ≥80 years. These findings underscore the importance of adjusting for hysterectomy prevalence to avoid underestimating cervical cancer incidence rates and masking disparities by age, race, and geographic region. This article is part of a Special Collection on Gynecological Cancers.

Public, Environmental & Occupational Health↗
DOE OSTI2014

Genotype, development and tissue-derived variation of cell-wall properties in the lignocellulosic energy crop Miscanthus

Species and hybrids of the genus Miscanthus contain attributes that make them front-runners among current selections of dedicated bioenergy crops. A key trait for plant biomass conversion to biofuels and biomaterials is cell-wall quality; however, knowledge of cell-wall composition and biology in Miscanthus species is limited. This study presents data on cell-wall compositional changes as a function of development and tissue type across selected genotypes, and considers implications for the development of miscanthus as a sustainable and renewable bioenergy feedstock. Cell-wall biomass was analysed for 25 genotypes, considering different developmental stages and stem vs. leaf compositional variability, by Fourier transform mid-infrared spectroscopy and lignin determination. In addition, a Clostridium phytofermentans bioassay was used to assess cell-wall digestibility and conversion to ethanol. Important cell-wall compositional differences between miscanthus stem and leaf samples were found to be predominantly associated with structural carbohydrates. Lignin content increased as plants matured and was higher in stem tissues. Although stem lignin concentration correlated inversely with ethanol production, no such correlation was observed for leaves. Leaf tissue contributed significantly to total above-ground biomass at all stages, although the extent of this contribution was genotype-dependent. In conclusion, it is hypothesized that divergent carbohydrate compositions and modifications in stem and leaf tissues are major determinants for observed differences in cell-wall quality. The findings indicate that improvement of lignocellulosic feedstocks should encompass tissue-dependent variation as it affects amenability to biological conversion. For gene-trait associations relating to cell-wall quality, the data support the separate examination of leaf and stem composition, as tissue-specific traits may be masked by considering only total above-ground biomass samples, and sample variability could be mostly due to varying tissue contributions to total biomass.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Induced and natural variation affect traits independently in hybrid Populus

Abstract The genetic control of many plant traits can be highly complex. Both allelic variation (sequence change) and dosage variation (copy number change) contribute to a plant's phenotype. While numerous studies have investigated the effect of allelic or dosage variation, very few have documented both within the same system, leaving their relative contribution to phenotypic effects unclear. The Populus genome is highly polymorphic, and poplars are fairly tolerant of gene dosage variation. Here, using a previously established Populus hybrid F1 population, we assessed and compared the effect of natural allelic variation and induced dosage variation on biomass, phenology, and leaf morphology traits. We identified QTLs for many of these traits, but our results indicate limited overlap between the QTLs associated with natural allelic variation and induced dosage variation. Additionally, the integration of data from both allelic and dosage variation identifies a larger set of QTLs that together explain a larger percentage of the phenotypic variance. Finally, our results suggest that the effect of the large indels might mask that of allelic QTLs. Our study helps clarify the relationship between allelic and dosage variation and their effects on quantitative traits.

Guo, Weier (ORCID:0000000251789334)↗
DOE OSTI2025

Divide and conquer: separating the two probabilities in seismic phase picking

There are two fundamental probabilities in the seismic phase picking process—the probability of the existence of a seismic phase (detection probability) and the probability associated with the phase arrival time estimation (timing probability). The nearly ubiquitous approach in developing deep learning phase picking models is to use a kernel, such as a truncated Gaussian, to mask the labelled phase arrival time and train a segmentation model. Once a model is trained, the times of the peaks in the output are taken as phase arrival times (picks), and the height of the peaks are taken as ‘probability’ of the picks. Here, we show that this ‘probability’ represents neither the detection nor the timing probability because this approach forces the output to follow the shape of the kernel. We introduce an approach using two models to estimate these two distinct probabilities. We use a binary classifier with a calibrated confidence to address the detection probability and a multiclass classifier to obtain a probability mass function to address the timing probability. This new approach can make the deep learning-based phase picking process more interpretable and provide options to logically control seismic monitoring workflows.

58 GEOSCIENCES↗
DOE OSTI2017

Box tomography: localized imaging of remote targets buried in an unknown medium, a step forward for understanding key structures in the deep Earth

We discuss an application of tomographic methods to the imaging of localized geological structures buried inside the Earth, where neither seismic sources nor receivers are necessarily present. We call this ‘box tomography’. The essential difference between box-tomography and standard tomographic methods is that the numerical modelling (i.e. the ray tracing in traveltime tomography and the wave propagation in waveform tomography or full waveform inversion) is completely confined within the small box-region imaged. Thus, box tomography is a lot more efficient than global tomography (i.e. where we invert for the velocity in the larger volume that encompasses all the sources and receivers), for imaging localized objects. The principal difficulty in the box tomography problem comes from the medium outside the box-region imaged, that masks the target structure. In the data recorded at the surface, the information carried by the waves about the target structure is mixed with that about the surrounding medium. The main focus of this paper is to evaluate how well box tomography can extract useful information to produce accurate images of remote buried objects, especially in the difficult situation where the velocity distribution above the target structure is not known a priori. We implemented traveltime box tomography, where first arrival times are inverted using ray theory, and, waveform box tomography or full waveform box inversion, where seismograms are inverted using either scattering integrals or adjoint methods. Whatever the method employed, we found that, in the simple situation where the velocity structure is known around the target region, box-tomography is faster and more accurate than global tomography. Most importantly, through examples and simple analysis, we show that box-tomography can produce accurate images of localized structures even though the velocity distribution is not a priori known around the box-region imaged. In the last section of this paper, we evaluate the usage of box-tomography for imaging geological structures in the deep Earth. We performed 2-D synthetic experiments in a fluid planet and we argue that box tomography can be employed for refining our current global tomographic models within arbitrary regions inside the Earth. This has important implications for understanding the composition and dynamics of the Earth’s interior.

Masson, Yder↗
DOE OSTI2020

Wobbly discs – corrugations seen in the dust lanes of edge-on galaxies

ABSTRACT We report the detection of small-scale bending waves, also known as corrugations, in the dust lanes of five nearby edge-on disc galaxies. This phenomenon, where the disc mid-plane bends to become wavy, just as in warps but on a smaller scale, is seen here for the first time, in the dust lanes running across the discs. Because they are seen in absorption, this feature must be present in the dust disc in the outskirts of these galaxies. We enhance the visibility of these features using unsharp masking, trace the dust mid-plane across the disc, measure the corrugation amplitude by eye and the corrugation wavelength using Fourier analysis. The corrugation amplitude is found to be in the range of 70–300pc and the wavelengths lie between 1 and 5 kpc. In this limited sample, we find that the amplitude of the corrugations tends to be larger for lower mass galaxies, whereas the wavelength of corrugation does not seem to depend on the mass of host galaxies. Linear stability analysis is performed to find out the dynamical state of these dust discs. Based on WKB analysis, we find that the dust corrugations in about half of our sample are stable. Further analysis, on a larger sample would be useful to strengthen the above results.

Narayan, Chaitra A.↗
DOE OSTI2020

Imaging systematics and clustering of DESI main targets

ABSTRACT We evaluate the impact of imaging systematics on the clustering of luminous red galaxies (LRG), emission-line galaxies (ELG), and quasars (QSO) targeted for the upcoming Dark Energy Spectroscopic Instrument (DESI) survey. Using Data Release 7 of the DECam Legacy Survey, we study the effects of astrophysical foregrounds, stellar contamination, differences between north galactic cap and south galactic cap measurements, and variations in imaging depth, stellar density, galactic extinction, seeing, airmass, sky brightness, and exposure time before presenting survey masks and weights to mitigate these effects. With our sanitized samples in hand, we conduct a preliminary analysis of the clustering amplitude and evolution of the DESI main targets. From measurements of the angular correlation functions, we determine power law fits $r_0 = 7.78 \pm 0.26\, h^{-1}$Mpc, γ = 1.98 ± 0.02 for LRGs and $r_0 = 5.45 \pm 0.1\, h^{-1}$Mpc, γ = 1.54 ± 0.01 for ELGs. Additionally, from the angular power spectra, we measure the linear biases and model the scale-dependent biases in the weakly non-linear regime. Both sets of clustering measurements show good agreement with survey requirements for LRGs and ELGs, attesting that these samples will enable DESI to achieve precise cosmological constraints. We also present clustering as a function of magnitude, use cross-correlations with external spectroscopy to infer dN/dz and measure clustering as a function of luminosity, and probe higher order clustering statistics through counts-in-cells moments.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Including massive neutrinos in thermal Sunyaev Zeldovich power spectrum and cluster counts analyses

We consistently include the effect of massive neutrinos in the thermal Sunyaev Zeldovich (SZ) power spectrum and cluster counts analyses, highlighting subtle dependencies on the total neutrino mass and data combination. In particular, we find that using the transfer functions for cold dark matter (CDM) + baryons in the computation of the halo mass function, instead of the transfer functions including neutrino perturbations, as prescribed in recent work, yields an ≈0.25 percent downward shift of the σ 8 constraint from tSZ power spectrum data, with a fiducial neutrino mass Σm ν = 0.06 eV. In ΛCDM, with an X-ray mass bias corresponding to the expected hydrostatic mass bias, i.e. (1 - b) ≃ 0.8, our constraints from Planck SZ data are consistent with the latest results from SPT, DES-Y1, and KiDS+VIKING-450. In νΛCDM, our joint analyses of Planck SZ with Planck 2015 primary CMB yield a small improvement on the total neutrino mass bound compared to the Planck 2015 primary CMB constraint, as well as (1 - b) = 0.64 ± 0.04 (68 percent CL). For forecasts, we find that competitive neutrino mass measurements using cosmic variance limited SZ power spectrum require masking the heaviest clusters and probing the small-scale SZ power spectrum up to ℓ max ≈ 10 4 . Although this is challenging, we find that SZ power spectrum can realistically be used to tightly constrain intracluster medium properties: we forecast a 2 percent determination of the X-ray mass bias by combining CMB-S4 and our mock SZ power spectrum with ℓ max = 10 3 .

Astronomy & Astrophysics↗
DOE OSTI2020

Optimal 1D Ly α forest power spectrum estimation – I. DESI-lite spectra

ABSTRACT The 1D Ly α forest flux power spectrum P1D is sensitive to scales smaller than a typical galaxy survey, and hence ties to the intergalactic medium’s thermal state, suppression from neutrino masses, and new dark matter models. It has emerged as a competitive framework to study new physics, but also has come with various challenges and systematic errors in analysis. In this work, we revisit the optimal quadratic estimator for P1D, which is robust against the relevant problems such as pixel masking, time evolution within spectrum, and quasar continuum errors. We further improve the estimator by introducing a fiducial power spectrum, which enables us to extract more information by alleviating the discreteness of band powers. We meticulously apply our method to synthetic Dark Energy Spectroscopic Instrument (DESI) spectra and demonstrate how the estimator overcomes each challenge. We further apply an optimization scheme that approximates the Fisher matrix to three elements per row and reduces computation time by 60 per cent. We show that we can achieve per cent precision in P1D with 5-yr DESI data in the absence of systematics and provide forecasts for different spectral qualities.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

A novel CMB component separation method: hierarchical generalized morphological component analysis

ABSTRACT We present a novel technique for cosmic microwave background (CMB) foreground subtraction based on the framework of blind source separation. Inspired by previous work incorporating local variation to generalized morphological component analysis (GMCA), we introduce hierarchical GMCA (HGMCA), a Bayesian hierarchical graphical model for source separation. We test our method on Nside = 256 simulated sky maps that include dust, synchrotron, free–free, and anomalous microwave emission, and show that HGMCA reduces foreground contamination by $25{{\ \rm per\ cent}}$ over GMCA in both the regions included and excluded by the Planck UT78 mask, decreases the error in the measurement of the CMB temperature power spectrum to the 0.02–0.03 per cent level at ℓ > 200 (and $\lt 0.26{{\ \rm per\ cent}}$ for all ℓ), and reduces correlation to all the foregrounds. We find equivalent or improved performance when compared to state-of-the-art internal linear combination type algorithms on these simulations, suggesting that HGMCA may be a competitive alternative to foreground separation techniques previously applied to observed CMB data. Additionally, we show that our performance does not suffer when we perturb model parameters or alter the CMB realization, which suggests that our algorithm generalizes well beyond our simplified simulations. Our results open a new avenue for constructing CMB maps through Bayesian hierarchical analysis.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

The growth of intracluster light in XCS-HSC galaxy clusters from 0.1 < z < 0.5

ABSTRACT We estimate the intracluster light (ICL) component within a sample of 18 clusters detected in the XMM Cluster Survey (XCS) data using the deep (∼26.8 mag) Hyper Suprime-Cam Subaru Strategic Programme data release 1 i-band data. We apply a rest-frame μB = 25 mag arcsec−2 isophotal threshold to our clusters, below which we define light as the ICL within an aperture of RX,500 (X-ray estimate of R500) centred on the brightest cluster galaxy (BCG). After applying careful masking and corrections for flux losses from background subtraction, we recover ∼20 per cent of the ICL flux, approximately four times our estimate of the typical background at the same isophotal level (${\sim}5{{\ \rm per\ cent}}$). We find that the ICL makes up about ${\sim}24{{\ \rm per\ cent}}$ of the total cluster stellar mass on average (∼41 per cent including the flux contained in the BCG within 50 kpc); this value is well matched with other observational studies and semi-analytic/numerical simulations, but is significantly smaller than results from recent hydrodynamical simulations (even when measured in an observationally consistent way). We find no evidence for any links between the amount of ICL flux with cluster mass, but find a growth rate of 2–4 for the ICL between 0.1 < z < 0.5. We conclude that the ICL is the dominant evolutionary component of stellar mass in clusters from z ∼ 1. Our work highlights the need for a consistent approach when measuring ICL alongside the need for deeper imaging, in order to unambiguously measure the ICL across as broad a redshift range as possible (e.g. 10-yr stacked imaging from the Vera C. Rubin Observatory).

Furnell, Kate E.↗
DOE OSTI2021

Galaxy clustering in harmonic space from the dark energy survey year 1 data: compatibility with real-space results

ABSTRACT We perform an analysis in harmonic space of the Dark Energy Survey Year 1 Data (DES-Y1) galaxy clustering photometric data using products obtained for the real-space analysis. We test our pipeline with a suite of lognormal simulations, which are used to validate scale cuts in harmonic space as well as to provide a covariance matrix that takes into account the DES-Y1 mask. We then apply this pipeline to DES-Y1 data taking into account survey property maps derived for the real-space analysis. We compare with real-space DES-Y1 results obtained from a similar pipeline. We show that the harmonic space analysis we develop yields results that are compatible with the real-space analysis for the bias parameters. This verification paves the way to performing a harmonic space analysis for the upcoming DES-Y3 data.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Dark Energy Survey year 3 results: covariance modelling and its impact on parameter estimation and quality of fit

ABSTRACT We describe and test the fiducial covariance matrix model for the combined two-point function analysis of the Dark Energy Survey Year 3 (DES-Y3) data set. Using a variety of new ansatzes for covariance modelling and testing, we validate the assumptions and approximations of this model. These include the assumption of Gaussian likelihood, the trispectrum contribution to the covariance, the impact of evaluating the model at a wrong set of parameters, the impact of masking and survey geometry, deviations from Poissonian shot noise, galaxy weighting schemes, and other sub-dominant effects. We find that our covariance model is robust and that its approximations have little impact on goodness of fit and parameter estimation. The largest impact on best-fitting figure-of-merit arises from the so-called fsky approximation for dealing with finite survey area, which on average increases the χ2 between maximum posterior model and measurement by $3.7{{\ \rm per\ cent}}$ (Δχ2 ≈ 18.9). Standard methods to go beyond this approximation fail for DES-Y3, but we derive an approximate scheme to deal with these features. For parameter estimation, our ignorance of the exact parameters at which to evaluate our covariance model causes the dominant effect. We find that it increases the scatter of maximum posterior values for Ωm and σ8 by about $3{{\ \rm per\ cent}}$ and for the dark energy equation-of-state parameter by about $5{{\ \rm per\ cent}}$.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Fractal dimension of optical cirrus in Stripe82

ABSTRACT The geometric characteristics of dust clouds provide important information on the physical processes that structure such clouds. One of such characteristics is the 2D fractal dimension D of a cloud projected on to the sky plane. In previous studies, which were mostly based on infrared (IR) data, the fractal dimension of individual clouds was found to be in a range from 1.1 to 1.7 with a preferred value of 1.2–1.4. In this work, we use data from Stripe82 of the Sloan Digital Sky Survey to measure the fractal dimension of the cirrus clouds. This is done here for the first time for optical data with significantly better resolution as compared to IR data. To determine the fractal dimension, the perimeter-area method is employed. We also consider IR (IRAS and Herschel) counterparts of the corresponding optical fields to compare the results between the optical and IR. We find that the averaged fractal dimension across all clouds in the optical is $\langle D \rangle =1.69^{+0.05}_{-0.05}$ which is significantly larger than the fractal dimension of its IR counterparts $\langle D\rangle =1.38^{+0.07}_{-0.06}$. We examine several reasons for this discrepancy (choice of masking and minimal contour level, image and angular resolution, etc.) and find that for approximately half of our fields the different angular resolution (point spread function) of the optical and IR data can explain the difference between the corresponding fractal dimensions. For the other half of the fields, the fractal dimensions of the IR and visual data remain inconsistent, which can be associated with physical properties of the clouds, but further physical simulations are required to prove it.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Characterizing the target selection pipeline for the Dark Energy Spectroscopic Instrument Bright Galaxy Survey

ABSTRACT We present the steps taken to produce a reliable and complete input galaxy catalogue for the Dark Energy Spectroscopic Instrument (DESI) Bright Galaxy Survey (BGS) using the photometric Legacy Survey DR8 DECam. We analyse some of the main issues faced in the selection of targets for the DESI BGS, such as star–galaxy separation, contamination by fragmented stars and bright galaxies. Our pipeline utilizes a new way to select BGS galaxies using Gaia photometry and we implement geometrical and photometric masks that reduce the number of spurious objects. The resulting catalogue is cross-matched with the Galaxy And Mass Assembly (GAMA) survey to assess the completeness of the galaxy catalogue and the performance of the target selection. We also validate the clustering of the sources in our BGS catalogue by comparing with mock catalogues and the Sloan Digital Sky Survey (SDSS) data. Finally, the robustness of the BGS selection criteria is assessed by quantifying the dependence of the target galaxy density on imaging and other properties. The largest systematic correlation we find is a 7 per cent suppression of the target density in regions of high stellar density.

79 ASTRONOMY AND ASTROPHYSICS↗