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All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Retrospective Search for Strongly Lensed Supernovae in the DESI Legacy Imaging Surveys

The introduction of deep wide-field surveys in recent years and the adoption of machine-learning techniques have led to the discoveries of $\mathcal{O}$(10 4 ) strong gravitational lensing systems and candidates. However, the discovery of multiply-lensed transients remains a rarity. Lensed transients and especially lensed supernovae are invaluable tools to cosmology because they allow us to constrain cosmological parameters via lens modeling and the measurements of their time delays. In this paper, we develop a pipeline to perform a targeted lensed transient search. We apply this pipeline to 5807 strong lenses and candidates, which were identified in the literature, in the DESI Legacy Imaging Surveys Data Release 9 (DR9) footprint. For each system, we analyze every exposure in all of the observed bands (DECam g, r, and z). Our pipeline finds, groups, and ranks detections that are in sufficient proximity temporally and spatially. After the first round of inspection, for promising candidate systems, we further examine the newly available DR10 data (with additional i and Y bands). Here we present our targeted lensed supernova search pipeline and seven new lensed supernova candidates, including a very likely lensed supernova—probably a Type Ia—in a system with an Einstein radius of ~1$^{"}_{.}$5.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Dimming the Lights: 2D Simulations of Deflagrations of Hybrid C/O/Ne White Dwarfs Using FLASH

The dimmest and most numerous outlier of the Type Ia supernova population, the Type Iax event, is increasingly being found in the results of observational campaigns. There is currently no single accepted model to describe these events. This 2D study explores the viability of modeling Type Iax events as a hybrid C/O/Ne white dwarf progenitor undergoing a deflagration using the multiphysics software FLASH. This hybrid was created using the stellar evolution code MESA, and its C-depleted core and mixed structure have demonstrated lower yields than traditional C/O progenitors in previous deflagration-to-detonation studies. To generate a sample, 30 “realizations” of this simulation were performed, the only difference being the shape of the initial match head used to start the deflagration. Consistent with earlier work, these realizations produce the familiar hot dense bound remnant surrounded by sparse ejecta. Our results indicate that the majority of the star remains unburned (∼70%) and bound (>90%). Our realizations produce total ejecta yields on the order of 10 −2 –10 −1 M ☉ , ejected 56 Ni yields on the order of 10 −4 –10 −2 M ☉ , and ejecta kinetic energies on the order of 10 48 –10 49 erg. Compared to yields inferred from recent observations of the dimmest Type Iax events—SN 2007qd, SN 2008ha, SN 2010ae, SN 2019gsc, SN 2019muj, SN 2020kyg, and SN 2021fcg—our simulation produces comparable 56 Ni yields but too-small total yields and kinetic energies. Reignition of the remnant is also seen in some realizations.

Hydrodynamical simulations↗
NASA NTRS1996

Trials and Tribulations of Implementing Intranet Technology: The Cassini Information Access System

The Cassini Information Access System (IAS) was built to provide Cassini Integration and Test engineers with ready access to current technical and logistical project information. World Wide Web (WWW) technology was used to provide a consistent user interface to pre-existing interactive systems as well as new repositories and interactive services developed specifically for Cassini.

Cassini↗
DOE OSTI2019

A Thorium Metal‐Organic Framework with Outstanding Thermal and Chemical Stability

Abstract A new thorium metal‐organic framework (MOF), Th(OBA) 2 , where OBA is 4,4′‐oxybis(benzoic) acid, has been synthesized hydrothermally in the presence of a range of nitrogen‐donor coordination modulators. This Th‐MOF, described herein as GWMOF‐13, has been characterized by single‐crystal and powder X‐ray diffraction, as well as through a range of techniques including gas sorption, thermogravimetric analysis (TGA), solid‐state UV/Vis and luminescence spectroscopy. Single‐crystal X‐ray diffraction analysis of GWMOF‐13 reveals an interesting, high symmetry (cubic Ia d ) structure, which yields a novel srs‐a topology. Most notably, TGA analysis of GWMOF‐13 reveals framework stability to 525 °C, matching the thermal stability benchmarks of the UiO‐66 series MOFs and zeolitic imidazolate frameworks (ZIFs), and setting a new standard for thermal stability in f‐block based MOFs.

Carter, Korey P.↗
DOE OSTI2022

Conservative solute transport processes and associated transient storage mechanisms: Comparing streams with contrasting channel morphologies, land use and land cover

Abstract Land use within a watershed impacts stream channel morphology and hydrology and, therefore, in‐stream solute transport processes and associated transient storage mechanisms. This study evaluated transport processes in two contrasting stream sites where channel morphology was influenced by the surrounding land use, land cover, climate and geologic controls: Como Creek, CO, a relatively undisturbed, high gradient, forested stream with a gravel bed and complex channel morphology, and Clear Creek, IA, an incised, low‐gradient stream with low‐permeability substrate draining an agricultural landscape. We performed conservative stream tracer injections at these sites to address the following questions: (1) How does solute transport vary between streams with differing morphologies? and (2) How does solute transport at each stream site change as a function of discharge? We analysed in‐stream tracer time series data and compared results quantifying solute attenuation in surface and subsurface transient storage zones. Significant trends were observed in these metrics with varying discharge conditions at the forested site but not at the agricultural site. There was a broad range of transport mechanisms and evidence of substantial exchange with both surface and hyporheic transient storage in the relatively undisturbed, forested stream. Changing discharge conditions activated or deactivated different solute transport mechanisms in the forested site and greatly impacted advective travel time. Conversely in the simplified agricultural stream, there was a narrow range of solute transport behaviour across flows and predominantly surface transient storage at all measured discharge conditions. These results demonstrate how channel simplification inhibits available solute transport mechanisms across varying discharge conditions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

750 GeV diphotons: implications for supersymmetric unification II

Perturbative supersymmetric gauge coupling unification is possible in six theories where complete SU (5) TeV-scale multiplets of vector matter account for the size of the reported 750 GeV diphoton resonance, interpreted as a singlet multiplet S=(s+ia)/√2. One of these has a full generation of vector matter and a unified gauge coupling αG ~ 1. The diphoton signal rate is enhanced by loops of vector squarks and sleptons, especially when the trilinear A couplings are large. If the SH u H d coupling is absent, both s and a can contribute to the resonance, which may then have a large apparent width if the mass splitting from s and a arises from loops of vector matter. The width depends sensitively on A parameters and phases of the vector squark and slepton masses. Vector quarks and/or squarks are expected to be in reach of the LHC. If the SH u H d coupling is present, a leads to a narrow diphoton resonance, while a second resonance with decays s → hh, W + W – , ZZ is likely to be discovered at future LHC runs. In some of the theories a non-standard origin or running of the soft parameters is required, for example involving conformal hidden sector interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

ChEVAS: Combining Suprarenal EVAS with Chimney Technique

Endovascular sealing with the Nellix{sup ®} endoprosthesis (EVAS) is a new technique to treat infrarenal abdominal aortic aneurysms. We describe the use of endovascular sealing in conjunction with chimney stents for the renal arteries (chEVAS) in two patients, one with a refractory type Ia endoleak and an expanding aneurysm, and one with a large juxtarenal aneurysm unsuitable for fenestrated endovascular repair (EVAR). Both aneurysms were successfully excluded. Our report confirms the utility of chEVAS in challenging cases, where suprarenal seal is necessary. We suggest that, due to lack of knowledge on its durability, chEVAS should only been considered when more conventional treatment modalities (open repair and fenestrated EVAR) are deemed difficult or unfeasible.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Early- and Mid-term Results of the Chimney Technique in the Repair of Aortic Arch Pathologies

PurposeTo examine the safety, feasibility, and mid-term efficacy of the chimney technique for aortic arch pathologies.MethodsFrom February 2011 to December 2014, a total of 35 patients (30 men; mean age 54.3 ± 14.1 years) with aortic arch pathologies underwent thoracic endovascular aortic repair combined with chimney stents. The indication was a proximal landing zone <1.5 cm. Follow-up was performed at 3, 6, and 12 months and then yearly thereafter.ResultsA total of 36 chimney stents were deployed (innominate artery, n = 1; left common carotid artery, n = 9; right subclavian artery, n = 1; left subclavian artery, n = 25). The technical success rate was 94.3 % (33/35). Immediate type Ia endoleaks (ELIa) were observed in two patients (8.6 %, 2/35). Twenty-five patients were successfully followed-up for a median period of 29.3 months (range, 6–48 months). One patient died due to aortic dissection aneurysm rupture at 36 months (mortality rate of 4 %, 1/25). Three late ELIa were observed and no reinterventions were performed. The overall incidence of ELIa was 20 % (5/25). During follow-up, the patency rate for chimney stents was 92 % (23/25).ConclusionOur limited experience demonstrates that the chimney technique is a viable and relatively safe treatment for patients with challenging thoracic aortic pathologies at least in the mid-term follow-up period.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Histologic Analysis with the Newly Designed Exoskeleton Seal{sup ®} Stent-Graft in the Porcine Abdominal Aorta

Purpose: To investigate the technical feasibility of a novel exoskeleton Seal{sup ®} stent-graft and analyze early histologic changes in the porcine abdominal aorta. Materials and Methods: Six pigs received an abdominal stent-graft (Group I), and six received an iliac branch stent-graft (Group II). Groups were subdivided as follows: Group Ia, which received three bifurcated main-body stent-grafts; Group Ib, which received three bifurcated main-body stent-grafts with both iliac graft-stents; Group IIa, which received three simple uni-iliac tapered stent-grafts; and Group IIb, which received three uni-iliac tapered tapered stent-grafts with right straight limb and left branched limb. Statistical analyses were performed with the Wilcoxon signed-rank test and mixed-model regression analysis. Results: The primary technical success rate (< 24 h) was 83% because of two acute thromboses in the lumen of the stented abdominal aorta immediately after stent-graft placement. At 4 weeks, late thrombosis occurred in two pigs. Higher mean neointimal hyperplasia areas (23.5% vs. 16.2%; P = .047), neointimal hyperplasia thicknesses (545.5 μm vs. 422.2 μm; P = .001), and degrees of collagen deposition (2.71 vs. 2.33; P = .002) were observed at the bare-metal stent-graft compared with the proximal exoskeleton portion of the stent-graft, with no significant differences between the patent and occluded groups or among the four types of stent-grafts. Conclusions: The exoskeleton stent-graft demonstrates 66% of patency rate during 1-month follow-up due to four cases of thromboses; however, the endothelialization on the junction of proximal graft showed no significant differences between the patent and occluded groups. Further studies should investigate long-term outcomes with prolonged neointimal hyperplasia.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Observational constraints on the tilted flat-XCDM and the untilted nonflat XCDM dynamical dark energy inflation parameterizations

In this work, we constrain tilted spatially-flat and untilted nonflat XCDM dynamical dark energy inflation parameterizations using Planck 2015 cosmic microwave background (CMB) anisotropy data and recent baryonic acoustic oscillations distance measurements, Type Ia supernovae data, Hubble parameter observations, and growth rate measurements. Inclusion of the four non-CMB data sets results in a significant strengthening of the evidence for nonflatness in the nonflat XCDM model from 1.1σ for the CMB data alone to 3.4σ for the full data combination. In this untilted nonflat XCDM case the data favor a spatially-closed model in which spatial curvature contributes a little less than a percent of the current cosmological energy budget; they also mildly favor dynamical dark energy over a cosmological constant at 1.2σ. These data are also better fit by the flat-XCDM parameterization than by the standard ΛCDM model, but only at 0.3σ significance. Current data is unable to rule out dark energy dynamics. The nonflat XCDM parameterization is compatible with the Dark Energy Survey limits on the present value of the rms mass fluctuations amplitude (σ 8 ) as a function of the present value of the nonrelativistic matter density parameter (Ω m ). Furthermore, it does not provide as good a fit to the higher multipole CMB temperature anisotropy data as does the standard tilted flat-ΛCDM model. A number of measured cosmological parameter values differ significantly when determined using the tilted flat-XCDM and the nonflat XCDM parameterizations, including the baryonic matter density parameter and the reionization optical depth.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Measuring the Hubble constant and spatial curvature from supernova apparent magnitude, baryon acoustic oscillation, and Hubble parameter data

Cosmic microwave background (CMB) anisotropy (spatial inhomogeneity) data provide the tightest constraints on the Hubble constant, matter density, spatial curvature, and dark energy dynamics. Other data, sensitive to the evolution of only the spatially homogeneous part of the cosmological model, such as Type Ia supernova apparent magnitude, baryon acoustic oscillation distance, and Hubble parameter measurements, can be used in conjunction with the CMB data to more tightly constrain parameters. Recent joint analyses of CMB and such non-CMB data indicate that slightly closed spatial hypersurfaces are favored in nonflat untilted inflation models and that dark energy dynamics cannot be ruled out, and favor a smaller Hubble constant. Here, we show that the constraints that follow from these non-CMB data alone are consistent with those that follow from the CMB data alone and so also consistent with, but weaker than, those that follow from the joint analyses of the CMB and non-CMB data.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

d{sup 0} Half-Metallic Ferromagnetism in CaN and CaAs Pnictides: an Ab Initio Study

Conventional magnetism occurs in systems which contain transition metals or rare earth ions with partially filled d or f shells. It is theoretically predicted that compounds of groups IA and IIA with IV and V, in some structural phases, are ferromagnetic half-metals which made them new candidates for spintronics applications. Employing density functional theory (DFT), we investigate magnetism in binary compounds CaN and CaAs. Regarding the structure of analogous magnetic materials and experimental results of CaAs synthesis, we have considered two cubic structures: rocksalt (RS) and zincblende (ZB), and four hexagonal structures: NiAs, wurtzite (WZ), anti-NiAs, and NaO. The calculated results show that CaN in cubic, NiAs, and wurtzite structures, and CaAs only in zincblende phase have ferromagnetic ground states with a magnetic moment of 1 μ{sub B}. Electronic structure analysis of these materials indicates that magnetism originates from anion p states. Existence of flat p bands and consequently high density of states at the Fermi level of magnetic structures gives rise to Stoner spin splitting and spontaneous ferromagnetism.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Mechanistic insights into the pyrolysis of poly (vinyl chloride)

The accumulation of unmanaged plastic waste in the environment has a devastating impact upon marine life and human health. Catalytic and thermal pyrolysis are promising technologies toward the efficient utilization of plastic waste. Yet, the processing of polymers, such as polyvinyl chloride (PVC), that decompose into corrosive compounds remains a major challenge. In this work, we employ density functional theory (DFT) and thermogravimetric analysis (TGA) to explore the elementary chemical steps that underpin the thermal decomposition of PVC. We determine that the dehydrochlorination reaction (i.e., 1 st stage of thermal decomposition) begins in tertiary chloride defects and propagates via HCl–mediated autocatalysis of internal allylic (IA) chloride groups. The latter groups, when in the vicinity of π–conjugated polymer segments, release HCl in a facile manner. We predict that other compounds, including hydrogen halides and H 2 O could also catalyze PVC’s dehydrochlorination. We suggest that hydrogen halides are the most efficient catalysts for this process, while other compounds like H 2 O may slow down the dehydrochlorination compared to purely HCl-catalyzed process, because of the dilution of the produced HCl. This result is corroborated by TGA experiments. Additionally, we study the thermochemistry and kinetics of polyene chain crosslinking and the formation of aromatics. The former reaction proceeds in parallel with the dehydrochlorination process (i.e., during the 1st stage of thermal decomposition), whilst the latter may occur at high temperatures (i.e., during the 2 nd stage of thermal decomposition). Furthermore, this work contributes to the fundamental understanding of molecular scale phenomena that take place during PVC pyrolysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Unveiling the Universe with emerging cosmological probes

The detection of the accelerated expansion of the Universe has been one of the major breakthroughs in modern cosmology. Several cosmological probes (Cosmic Microwave Background, Supernovae Type Ia, Baryon Acoustic Oscillations) have been studied in depth to better understand the nature of the mechanism driving this acceleration, and they are being currently pushed to their limits, obtaining remarkable constraints that allowed us to shape the standard cosmological model. In parallel to that, however, the percent precision achieved has recently revealed apparent tensions between measurements obtained from different methods. These are either indicating some unaccounted systematic effects, or are pointing toward new physics. Following the development of CMB, SNe, and BAO cosmology, it is critical to extend our selection of cosmological probes. Novel probes can be exploited to validate results, control or mitigate systematic effects, and, most importantly, to increase the accuracy and robustness of our results. This review is meant to provide a state-of-art benchmark of the latest advances in emerging “beyond-standard” cosmological probes. We present how several different methods can become a key resource for observational cosmology. In particular, we review cosmic chronometers, quasars, gamma-ray bursts, standard sirens, lensing time-delay with galaxies and clusters, cosmic voids, neutral hydrogen intensity mapping, surface brightness fluctuations, stellar ages of the oldest objects, secular redshift drift, and clustering of standard candles. The review describes the method, systematics, and results of each probe in a homogeneous way, giving the reader a clear picture of the available innovative methods that have been introduced in recent years and how to apply them. The review also discusses the potential synergies and complementarities between the various probes, exploring how they will contribute to the future of modern cosmology.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

Capitalizing on tumor genotyping: Towards the design of mutation specific inhibitors of phosphoinsitide-3-kinase

PI3Ks catalyze the phosphorylation of the inositol hydroxyls of phosphoinositide membrane components. The changes in phosphorylation of the inositides recruit proteins to the plasma membrane that initiate important signaling cascades. PI3K{alpha}, one of the class IA PI3Ks, is highly mutated in cancers. All mutations analyzed result in an increase in enzymatic activity. The structures of this enzyme determined by X-ray diffraction, provide a framework for analyzing the possible structural effect of these mutations and their effect on the enzymatic activity. Many of the mutations occur at domain interfaces where they can affect domain interactions and relieve the inhibition of the wild-type enzyme by the nSH2 domain of p85. This mechanism is analogous to the mechanism of physiological activation by activated tyrosine-kinase receptors in which the phosphorylated tyrosine of the receptor (or their substrates) dislodges the nSH2 from its inhibitory position in the complex by competing with its binding to a loop in the helical domain. Other mutations in the kinase domain can directly affect the conformation of the catalytic site. One mutation, His1047Arg, uses a completely different mechanism: it changes the conformation of the C-terminal loop in such a way that it increases the interaction of the enzyme with the membrane, granting increased access to the phosphoinositide substrates. Taking advantage of the reliance of some cancers on the increased activity of mutated PI3K{alpha}, will require the development of isoform-specific, mutant-specific inhibitors. The structural, biochemical and physiological data that are becoming available for PI3Ks are an important first step in this direction.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Intertwined impacts of water, energy development, and carbon emissions in China

China is rapidly expanding its alternative and non-conventional energy production capabilities. Although renewable electricity remains the focus, considerable investment has supported construction of coal liquefaction and coal gasification facilities in the desert steppes of north-central China, new coal mines in arid Inner Mongolia, and tight oil and gas extraction in the Ordos to supplement limited domestic supplies of oil and gas. At the same time, China is also facing severe drought and water scarcity in these same regions and in response has expanded various water supply technologies such as desalination and wastewater treatment. Recent government goals and measures for reducing energy and water consumption and increasing efficiency introduced in national policies, however, are poorly or not coordinated, resulting in contradictory objectives for which physical interlinkages are not well understood. This research intends to provide insights for future energy-water nexus management decisions in China, through systematic, comprehensive modeling of the water-energy nexus in China based on comprehensive, bottom-up technology characterizations. Existing studies fail to adequately characterize the details on specific technologies, nor do they comprehensively cover all energy sectors, including energy conversion for non-energy products. We developed integrated assessment (IA) capabilities to allow stakeholders to observe the tradeoffs between various technology options and policy decisions and to test hypotheses/premises in a scenario-driven environment. The results of our analysis underscore the growing interconnection between water and energy in China, the mixed trade-offs from developing low-carbon technologies such as renewable energy and inland nuclear, and the importance of water-energy nexus issues at the regional and local scales. This study lays the groundwork for an integrated resource policy planning process in China and provides an assessment methodology and research directions for future studies of the water-energy nexus. To conclude, this study contributes to the water-energy nexus literature by providing systematic data and policy implications for China, where data are typically less accessible, as well as providing references for other regions in the world that are facing similar water and energy use and planning challenges.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2011

Silencing p110{beta} prevents rapid depletion of nuclear pAkt

Highlights: Black-Right-Pointing-Pointer p110{beta} was essential for the statin- and ATP-induced depletion of nuclear pAkt and an associated inhibition of growth. Black-Right-Pointing-Pointer p110{beta} knock-out inhibited statin-induced changes in binding between FKBP51, pAkt and PTEN. Black-Right-Pointing-Pointer Data supports the hypothesis that nuclear pAkt is important for anti-cancer effects of statins. -- Abstract: The p110{beta} subunit in the class IA PI3K family may act as an oncogene and is critical for prostate tumor development in PTEN knockout mice. We tested the possible involvement of p110{beta} in a recently described rapid depletion of phosphorylated Akt (pAkt) in the nucleus. Previous work showed that this down-regulation is induced by extracellular ATP or by statins and is mediated by the purinergic receptor P2X7. Here, we used p110{beta} knock out mouse embryonic fibroblasts (MEFs) and siRNA-treated cancer cells. We found that p110{beta} is essential for ATP- or statin-induced nuclear pAkt depletion in MEFs and in several cancer cell lines including prostate cancer cells. ATP, statin or the selective P2X7 agonist BzATP also inhibited cell growth, and this inhibition was not seen in p110{beta} knock out cells. We also found that p110{beta} was necessary for statin-induced changes in binding between FKBP51, pAkt and PTEN. Our data show that p110{beta} is essential for the ATP- and statin-induced effects and support a role of nuclear pAkt in cancer development. They also provide support for a chemopreventive effect of statins mediated by depletion of nuclear pAkt.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Incremental Interval Assignment by Integer Linear Algebra with Improvements

Interval Assignment (IA) is the problem of selecting the number of mesh edges (intervals) for each curve for conforming quad and hex meshing. The intervals x is fundamentally integer-valued. Many other approaches perform numerical optimization then convert a floating-point solution into an integer solution, which is slow and error prone. We avoid such steps: we start integer, and stay integer. Incremental Interval Assignment (IIA) uses integer linear algebra (Hermite normal form) to find an initial solution to the meshing constraints, satisfying the integer matrix equation Solving for reduced row echelon form provides integer vectors spanning the nullspace of A. Here we add vectors from the nullspace to improve the initial solution, maintaining Ax = b Heuristics find good integer linear combinations of nullspace vectors that provide strict improvement towards variable bounds or goals. IIA always produces an integer solution if one exists. In practice we usually achieve solutions close to the user goals, but there is no guarantee that the solution is optimal, nor even satisfies variable bounds, e.g. has positive intervals. We describe several algorithmic changes since first publication that tend to improve the final solution. The software is freely available.

97 MATHEMATICS AND COMPUTING↗