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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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NASA NTRS2016

The Atacama Cosmology Telescope: Dynamical Masses for 44 SZ-Selected Galaxy Clusters over 755 Square Degrees

We present galaxy velocity dispersions and dynamical mass estimates for 44 galaxy clusters selected via the Sunyaev-Zeldovich (SZ) effect by the Atacama Cosmology Telescope. Dynamical masses for 18 clusters are reported here for the first time. Using N-body simulations, we model the different observing strategies used to measure the velocity dispersions and account for systematic effects resulting from these strategies. We find that the galaxy velocity distributions may be treated as isotropic, and that an aperture correction of up to 7 per cent in the velocity dispersion is required if the spectroscopic galaxy sample is sufficiently concentrated towards the cluster centre. Accounting for the radial profile of the velocity dispersion in simulations enables consistent dynamical mass estimates regardless of the observing strategy. Cluster masses M200 are in the range (1 - 15) times 10 (sup 14) Solar Masses. Comparing with masses estimated from the SZ distortion assuming a gas pressure profile derived from X-ray observations gives a mean SZ-to-dynamical mass ratio of 1:10 plus or minus 0:13, but there is an additional 0.14 systematic uncertainty due to the unknown velocity bias; the statistical uncertainty is dominated by the scatter in the mass-velocity dispersion scaling relation. This ratio is consistent with previous determinations at these mass scales.

Sunyaev-Zeldovich (SZ)↗
DOE OSTI2021

Collisional excitation of interstellar PN by H 2 : New interaction potential and scattering calculations

Here, rotational excitation of interstellar PN molecules induced by collisions with H 2 is investigated. We present the first ab initio four-dimensional potential energy surface (PES) for the PN–H 2 van der Waals system. The PES was obtained using an explicitly correlated coupled cluster approach with single, double, and perturbative triple excitations [CCSD(T)-F12b]. The method of interpolating moving least squares was used to construct an analytical PES from these data. The equilibrium structure of the complex was found to be linear, with H 2 aligned at the N end of the PN molecule, at an intermolecular separation of 4.2 Å. The corresponding well-depth is 224.3 cm -1 . The dissociation energies were found to be 40.19 cm -1 and 75.05 cm -1 for complexes of PN with ortho-H 2 and para-H 2 , respectively. Integral cross sections for rotational excitation in PN–H 2 collisions were calculated using the new PES and were found to be strongly dependent on the rotational level of the H 2 molecule. These new collisional data will be crucial to improve the estimation of PN abundance in the interstellar medium from observational spectra.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Mixed Valence {Ni 2+ Ni 1+ } Clusters as Models of Acetyl Coenzyme A Synthase Intermediates

Acetyl coenzyme A synthase (ACS) catalyzes the formation and deconstruction of the key biological metabolite, acetyl coenzyme A (acetyl-CoA). The active site of ACS features a {NiNi} cluster bridged to a [Fe4S4] n+ cubane known as the A-cluster. The mechanism by which the A-cluster functions is debated, with few model complexes able to replicate the oxidation states, coordination features, or reactivity proposed in the catalytic cycle. In this work, we isolate the first bimetallic models of two hypothesized intermediates on the paramagnetic pathway of the ACS function. The heteroligated {Ni 2+ Ni 1+ } cluster, [K(12-crown-4) 2 ][1], effectively replicates the coordination number and oxidation state of the proposed “A red ” state of the A-cluster. Addition of carbon monoxide to [1] - allows for isolation of a dinuclear {Ni 2+ Ni 1+ (CO)} complex, [K(12-crown-2) n ][2] (n = 1–2), which bears similarity to the “A NiFeC ” enzyme intermediate. Structural and electronic properties of each cluster are elucidated by X-ray diffraction, nuclear magnetic resonance, cyclic voltammetry, and UV/vis and electron paramagnetic resonance spectroscopies, which are supplemented by density functional theory (DFT) calculations. Calculations indicate that the pseudo-T-shaped geometry of the three-coordinate nickel in [1] – is more stable than the Y-conformation by 22 kcal mol –1 , and that binding of CO to Ni 1+ is barrierless and exergonic by 6 kcal mol –1 . UV/vis absorption spectroscopy on [2] - in conjunction with time-dependent DFT calculations indicates that the square-planar nickel site is involved in electron transfer to the CO π*-orbital. Further, we demonstrate that [2] - promotes thioester synthesis in a reaction analogous to the production of acetyl coenzyme A by ACS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Au3N3(Cl6O)2 by Materials Project

AuCl4Au2N(OCl4)2N2 crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of eight ammonia molecules, four Au2N(OCl4)2 clusters, and four AuCl4 clusters. In each Au2N(OCl4)2 cluster, Au3+ is bonded in a rectangular see-saw-like geometry to four Cl1- atoms. There are a spread of Au–Cl bond distances ranging from 2.30–2.43 Å. N+2.33+ is bonded in a linear geometry to two equivalent Cl1- atoms. Both N–Cl bond lengths are 2.08 Å. O2- is bonded in a single-bond geometry to one Cl1- atom. The O–Cl bond length is 1.53 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted bent 120 degrees geometry to one Au3+ and one N+2.33+ atom. In the second Cl1- site, Cl1- is bonded in a distorted bent 120 degrees geometry to one Au3+ and one O2- atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Au3+ atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Au3+ atom. In each AuCl4 cluster, Au3+ is bonded in a square co-planar geometry to four Cl1- atoms. There are two shorter (2.30 Å) and two longer (2.31 Å) Au–Cl bond lengths. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Au3+ atom. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Au3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H14RhC6NClO4 by Materials Project

RhC4NH8O4Cl(CH3)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of eight methane molecules and two RhC4NH8O4Cl clusters. In one of the RhC4NH8O4Cl clusters, Rh4+ is bonded in a distorted square pyramidal geometry to four O2- and one Cl1- atom. There are two shorter (2.07 Å) and two longer (2.08 Å) Rh–O bond lengths. The Rh–Cl bond length is 2.61 Å. There are four inequivalent C1- sites. In the first C1- site, C1- is bonded to one N3- and three H1+ atoms to form corner-sharing CH3N tetrahedra. The C–N bond length is 1.48 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the second C1- site, C1- is bonded in a distorted bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.28 Å. In the third C1- site, C1- is bonded to one N3- and three H1+ atoms to form corner-sharing CH3N tetrahedra. The C–N bond length is 1.48 Å. All C–H bond lengths are 1.09 Å. In the fourth C1- site, C1- is bonded in a distorted bent 120 degrees geometry to two O2- atoms. There is one shorter (1.28 Å) and one longer (1.29 Å) C–O bond length. N3- is bonded in a tetrahedral geometry to two C1- and two H1+ atoms. Both N–H bond lengths are 1.05 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- and one Cl1- atom. The H–Cl bond length is 2.10 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. Cl1- is bonded in a 2-coordinate geometry to one Rh4+ and one H1+ atom. In one of the RhC4NH8O4Cl clusters, Rh4+ is bonded in a distorted square pyramidal geometry to four O2- and one Cl1- atom. There are a spread of Rh–O bond distances ranging from 2.06–2.08 Å. The Rh–Cl bond length is 2.65 Å. There are four inequivalent C1- sites. In the first C1- site, C1- is bonded to one N3- and three H1+ atoms to form corner-sharing CH3N tetrahedra. The C–N bond length is 1.49 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the second C1- site, C1- is bonded to one N3- and three H1+ atoms to form corner-sharing CH3N tetrahedra. The C–N bond length is 1.49 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the third C1- site, C1- is bonded in a distorted bent 120 degrees geometry to two O2- atoms. There is one shorter (1.28 Å) and one longer (1.29 Å) C–O bond length. In the fourth C1- site, C1- is bonded in a distorted bent 120 degrees geometry to two O2- atoms. Both C–O bond lengths are 1.28 Å. N3- is bonded in a distorted tetrahedral geometry to two C1- and two H1+ atoms. There is one shorter (1.04 Å) and one longer (1.06 Å) N–H bond length. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- and one Cl1- atom. The H–Cl bond length is 2.05 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C1- atom. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Rh4+ and one C1- atom. Cl1- is bonded in a distorted L-shaped geometry to one Rh4+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on VH10S2(NO4)2 by Materials Project

VH6S2(NO3)2(H2O)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four water molecules and two VH6S2(NO3)2 clusters. In each VH6S2(NO3)2 cluster, V4+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.11 Å) and two longer (2.12 Å) V–O bond lengths. N3+ is bonded in a single-bond geometry to one S2- atom. The N–S bond length is 1.54 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.58 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. S2- is bonded in a distorted trigonal non-coplanar geometry to one N3+ and two O2- atoms. There is one shorter (1.55 Å) and one longer (1.81 Å) S–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one V4+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two H1+ and one S2- atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V4+ and one S2- atom.

36 MATERIALS SCIENCE↗
NASA NTRS1998

The Study of Clusters of Galaxies and Large Scale Structures

Many research projects have been initiated and completed under support of this program. The results are summarized below. The work on the ROSAT Deep Survey has been successfully completed. A number of interesting results have been established within this joint MPE, Cal Tech, JHU, ST ScI, ESO collaboration. First, a very large fraction, 70-80 percent, of the X-ray background has been directly resolved into point sources. We have derived a new log N-log S for X-ray sources and have measured a source density of 970 sources per square degree at a limiting flux level. Care was taken in these studies to accurately model and measure the effects of sources confusion. This was possible because of our observing strategy which included both deep PSPC and HRI observations. No evidence of a population of narrow emission line galaxies has been established but some evidence for the evolution of low luminosity AGN (Seyfert galaxies) has been reported. The work on the ROSAT All Sky Survey Northern Cluster Survey has been substantially concluded but the publication of the list has been held up by the need to analyze newly re-calibrated data. This should result in publication over the next year. During the past year we have submitted a paper to the Astrophysical Journal which utilized a sample of clusters originally selected from the ROSAT All-sky survey at redshifts greater than 0.3. This sample was studied with ASCA to determine temperature and luminosity.

Source record↗
DOE OSTI2023

A bis-calix[4]arene-supported [Cu II 16 ] cage

Reaction of 2,2'-bis-p- t Bu-calix[4]arene (H 8 L) with Cu(NO 3 ) 2 ·3H 2 O and N-methyldiethanolamine (Me-deaH 2 ) in a basic dmf/MeOH mixture affords [Cu II 16 (L) 2 (Me-dea) 4 (μ 4 -NO 3 ) 2 (μ-OH) 4 (dmf) 3.5 (MeOH) 0.5 (H 2 O) 2 ](H 6 L)·16dmf·4H 2 O (4), following slow evaporation of the mother liquor. The central core of the metallic skeleton describes a tetracapped square prism, [Cu 12 ], in which the four capping metal ions are the CuII ions housed in the calix[4]arene polyphenolic pockets. The [Cu II 8 ] square prism is held together “internally” by a combination of hydroxide and nitrate anions, with the N-methyldiethanolamine co-ligands forming dimeric [Cu II 2 ] units which edge-cap above and below the upper and lower square faces of the prism. Charge balance is maintained through the presence of one doubly deprotonated H 6 L 2- ligand per [Cu 16 ] cluster. Magnetic susceptibility measurements reveal the predominance of strong antiferromagnetic exchange interactions and an S = 1 ground state, while EPR is consistent with a large zero-field splitting.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on MgH16C4S4N2(O4F3)4 by Materials Project

MgH4S2(NO3)2(CF2)2(CH4O3F4)2(H2O)2(SO)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four difluoromethane molecules, four sulfur monoxide molecules, four water molecules, four CH4O3F4 clusters, and two MgH4S2(NO3)2 clusters. In each CH4O3F4 cluster, C4+ is bonded in a tetrahedral geometry to one H1+ and three F1- atoms. The C–H bond length is 1.10 Å. There is two shorter (1.36 Å) and one longer (1.37 Å) C–F bond length. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to one O2- and one F1- atom. The H–O bond length is 1.35 Å. The H–F bond length is 1.04 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one O2- and one F1- atom. The O–O bond length is 1.23 Å. The O–F bond length is 2.98 Å. In the second O2- site, O2- is bonded in a distorted linear geometry to one O2- and one F1- atom. The O–F bond length is 2.80 Å. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three H1+ atoms. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one C4+ and one O2- atom. In the second F1- site, F1- is bonded in a single-bond geometry to one H1+ and one O2- atom. In the third F1- site, F1- is bonded in a single-bond geometry to one C4+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one C4+ atom. In each MgH4S2(NO3)2 cluster, Mg2+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.02 Å) and two longer (2.19 Å) Mg–O bond lengths. N5+ is bonded in a bent 120 degrees geometry to one H1+ and one S atom. The N–H bond length is 1.05 Å. The N–S bond length is 1.55 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N5+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one S atom. The H–S bond length is 1.38 Å. S is bonded in a trigonal non-coplanar geometry to one N5+, one H1+, and one O2- atom. The S–O bond length is 1.53 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to one Mg2+ and one S atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mg2+ and one O2- atom. The O–O bond length is 1.26 Å. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one O2- atom.

36 MATERIALS SCIENCE↗
NASA NTRS2003

A Fast Implementation of the ISOCLUS Algorithm

Unsupervised clustering is a fundamental building block in numerous image processing applications. One of the most popular and widely used clustering schemes for remote sensing applications is the ISOCLUS algorithm, which is based on the ISODATA method. The algorithm is given a set of n data points in d-dimensional space, an integer k indicating the initial number of clusters, and a number of additional parameters. The general goal is to compute the coordinates of a set of cluster centers in d-space, such that those centers minimize the mean squared distance from each data point to its nearest center. This clustering algorithm is similar to another well-known clustering method, called k-means. One significant feature of ISOCLUS over k-means is that the actual number of clusters reported might be fewer or more than the number supplied as part of the input. The algorithm uses different heuristics to determine whether to merge lor split clusters. As ISOCLUS can run very slowly, particularly on large data sets, there has been a growing .interest in the remote sensing community in computing it efficiently. We have developed a faster implementation of the ISOCLUS algorithm. Our improvement is based on a recent acceleration to the k-means algorithm of Kanungo, et al. They showed that, by using a kd-tree data structure for storing the data, it is possible to reduce the running time of k-means. We have adapted this method for the ISOCLUS algorithm, and we show that it is possible to achieve essentially the same results as ISOCLUS on large data sets, but with significantly lower running times. This adaptation involves computing a number of cluster statistics that are needed for ISOCLUS but not for k-means. Both the k-means and ISOCLUS algorithms are based on iterative schemes, in which nearest neighbors are calculated until some convergence criterion is satisfied. Each iteration requires that the nearest center for each data point be computed. Naively, this requires O(kn) time, where k denotes the current number of centers. Traditional techniques for accelerating nearest neighbor searching involve storing the k centers in a data structure. However, because of the iterative nature of the algorithm, this data structure would need to be rebuilt with each new iteration. Our approach is to store the data points in a kd-tree data structure. The assignment of points to nearest neighbors is carried out by a filtering process, which successively eliminates centers that can not possibly be the nearest neighbor for a given region of space. This algorithm is significantly faster, because large groups of data points can be assigned to their nearest center in a single operation. Preliminary results on a number of real Landsat datasets show that our revised ISOCLUS-like scheme runs about twice as fast.

Memarsadeghi, Nargess↗
DOE OSTI2024

Equation of State and Thermometry of the 2D SU ( N ) Fermi-Hubbard Model

We characterize the equation of state (EoS) of the SU ( N > 2 ) Fermi-Hubbard Model (FHM) in a two-dimensional single-layer square optical lattice. We probe the density and the site occupation probabilities as functions of interaction strength and temperature for N = 3 , 4, and 6. Our measurements are used as a benchmark for state-of-the-art numerical methods including determinantal quantum Monte Carlo and numerical linked cluster expansion. By probing the density fluctuations, we compare temperatures determined in a model-independent way by fitting measurements to numerically calculated EoS results, making this a particularly interesting new step in the exploration and characterization of the SU ( N ) FHM. Published by the American Physical Society 2024

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on H16PdC4S4(N5O3)2 by Materials Project

PdC4H16(N2S)4(NO3)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two nitric acid molecules and one PdC4H16(N2S)4 cluster. In the PdC4H16(N2S)4 cluster, Pd2+ is bonded in a square co-planar geometry to four S2- atoms. There are two shorter (2.35 Å) and two longer (2.37 Å) Pd–S bond lengths. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted trigonal planar geometry to two N+1.40- and one S2- atom. There is one shorter (1.32 Å) and one longer (1.33 Å) C–N bond length. The C–S bond length is 1.76 Å. In the second C4+ site, C4+ is bonded in a distorted trigonal planar geometry to two N+1.40- and one S2- atom. There is one shorter (1.33 Å) and one longer (1.34 Å) C–N bond length. The C–S bond length is 1.72 Å. There are four inequivalent N+1.40- sites. In the first N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.03 Å. In the second N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the third N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the fourth N+1.40- site, N+1.40- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N+1.40- atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a water-like geometry to one Pd2+ and one C4+ atom. In the second S2- site, S2- is bonded in a water-like geometry to one Pd2+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The clustering of Lyman Alpha Emitting galaxies at 𝗓=2–3

Here, we measure the clustering of Lyman Alpha Emitting galaxies (LAEs) selected from the One-hundred-square-degree DECam Imaging in Narrowbands (ODIN) survey, with spectroscopic follow-up from Dark Energy Spectroscopic Instrument (DESI). We use DESI spectroscopy to optimize our selection and to constrain the interloper fraction and redshift distribution of our narrow-band selected sources. We select samples of 4000 LAEs at z = 2.45 and 3.1 in 9 sq. deg. centered on the COSMOS field with median Lyα fluxes of ≈ 10 -16 erg s -1 cm -2 . Covariances and cosmological inferences are obtained from a series of mock catalogs built upon high-resolution N-body simulations that match the footprint, number density, redshift distribution and observed clustering of the sample. We find that both samples have a correlation length of r 0 = 3.0 ± 0.2 h -1 Mpc. Within our fiducial cosmology these correspond to 3D number densities of ≈ 10 -3 h 3 Mpc -3 and, from our mock catalogs, biases of 1.7 and 2.0 at z= 2.45 and 3.1, respectively. We discuss the implications of these measurements for the use of LAEs as large-scale structure tracers for high-redshift cosmology.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2019

Discovery of Activities via Statistical Clustering of Fixation Patterns

Human behavior often consists of a series of distinct activities, each characterized by a unique pattern of interaction with the visual environment. This is true even in a restricted domain, such as a pilot flying an airplane; in this case, activities with distinct visual signatures might be things like communicating, navigating, monitoring, etc. We propose a novel analysis method for gaze-tracking data, to perform blind discovery of these hypothetical activities. We compare, not individual fixations, but groups of fixations aggregated over a fixed time interval (Tau). We assume that the environment has been divided into a finite set of discrete areas-of-interest (AOIs). For a given time interval, we compute the proportion of time spent fixating each AOI, resulting in an N-dimensional vector, where N is the number of AOIs. These proportions can be converted to integer counts by multiplying by Tau divided by the average fixation duration, a parameter that we fix at 283 milliseconds. We compare different intervals by computing the chi-squared statistic. The p-value associated with the statistic is the likelihood of observing the data under the hypothesis that the data in the two intervals were generated by a single process with a single set of probabilities governing the fixation of each AOI. We cluster the intervals, first by merging adjacent intervals that are sufficiently similar, optionally shifting the boundary between non-merged intervals to maximize the difference. Then we compare and cluster non-adjacent intervals. The method is evaluated using synthetic data generated by a hand-crafted set of activities. While the method generally finds more activities than put into the simulation, we have obtained agreement as high as 80 percent between the inferred activity labels and ground truth.

Eye Movements↗
DOE OSTI2021

Symbol alphabets from tensor diagrams

We propose to use tensor diagrams and the Fomin-Pylyavskyy conjectures to explore the connection between symbol alphabets of n-particle amplitudes in planar $\mathcal{N}$ = 4 Yang-Mills theory and certain polytopes associated to the Grassmannian Gr(4, n). We show how to assign a web (a planar tensor diagram) to each facet of these polytopes. Webs with no inner loops are associated to cluster variables (rational symbol letters). For webs with a single inner loop we propose and explicitly evaluate an associated web series that contains information about algebraic symbol letters. In this manner we reproduce the results of previous analyses of n ≤ 8, and find that the polytope $\mathcal{C}^†$(4,9) encodes all rational letters, and all square roots of the algebraic letters, of known nine-particle amplitudes.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Materials Data on NiH4C2(S2N)2 by Materials Project

NiC2H4(NS2)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four NiC2H4(NS2)2 clusters. Ni2+ is bonded in a square co-planar geometry to four S2- atoms. There are three shorter (2.20 Å) and one longer (2.21 Å) Ni–S bond lengths. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted trigonal planar geometry to one N3- and two S2- atoms. The C–N bond length is 1.33 Å. Both C–S bond lengths are 1.71 Å. In the second C4+ site, C4+ is bonded in a distorted single-bond geometry to one N3- and two S2- atoms. The C–N bond length is 1.32 Å. There is one shorter (1.71 Å) and one longer (1.72 Å) C–S bond length. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the second N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom. In the second S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom. In the third S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom. In the fourth S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiH4C2(S2N)2 by Materials Project

NiC2H4(NS2)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four NiC2H4(NS2)2 clusters. Ni2+ is bonded in a square co-planar geometry to four S2- atoms. There are one shorter (2.20 Å) and three longer (2.21 Å) Ni–S bond lengths. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted trigonal planar geometry to one N3- and two S2- atoms. The C–N bond length is 1.32 Å. There is one shorter (1.71 Å) and one longer (1.72 Å) C–S bond length. In the second C4+ site, C4+ is bonded in a distorted single-bond geometry to one N3- and two S2- atoms. The C–N bond length is 1.32 Å. Both C–S bond lengths are 1.72 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the second N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.03 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom. In the second S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom. In the third S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom. In the fourth S2- site, S2- is bonded in an L-shaped geometry to one Ni2+ and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoC12N8(ClO5)2 by Materials Project

CoO4(C5N4)2(CO2)2(ClO)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two formic acid molecules, two C5N4 clusters, one ClO cluster, and one CoO4 cluster. In each C5N4 cluster, there are five inequivalent C+3.67+ sites. In the first C+3.67+ site, C+3.67+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.30 Å. In the second C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.32 Å) and one longer (1.42 Å) C–N bond length. In the third C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.39 Å) and one longer (1.58 Å) C–N bond length. In the fourth C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.32 Å) and one longer (1.40 Å) C–N bond length. In the fifth C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.35 Å) and one longer (1.38 Å) C–N bond length. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a bent 120 degrees geometry to two C+3.67+ atoms. In the second N3- site, N3- is bonded in a bent 120 degrees geometry to two C+3.67+ atoms. In the third N3- site, N3- is bonded in a 3-coordinate geometry to three C+3.67+ atoms. In the fourth N3- site, N3- is bonded in a water-like geometry to two C+3.67+ atoms. In the ClO cluster, O2- is bonded in a distorted L-shaped geometry to two equivalent Cl1- atoms. There is one shorter (1.56 Å) and one longer (2.33 Å) O–Cl bond length. Cl1- is bonded in a 2-coordinate geometry to two equivalent O2- atoms. In the CoO4 cluster, Co2+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.64 Å) and two longer (1.88 Å) Co–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Co2+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Co2+ atom.

36 MATERIALS SCIENCE↗