Thermo-mechanical behavior of a single slice test device for the FRB High Power target.
Abstract not provided.
Pellemoine, F.↗
SEARCH · Engineering Papers
Results for “SLICING”
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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Multi-slice Energy Resolving CT system using a THCOBRA detector operating in NeCH 4
Not Available
Carramate, L. F. N. D.↗
Slice imaging of nitric acid photodissociation: The O({sup 1}D) + HONO channel
We report an imaging study of nitric acid (HNO{sub 3}) photodissociation near 204 nm with detection of O({sup 1}D), one of the major decomposition products in this region. The images show structure reflecting the vibrational distribution of the HONO coproduct and significant angular anisotropy that varies with recoil speed. The images also show substantial alignment of the O({sup 1}D) orbital, which is analyzed using an approximate treatment that reveals that the polarization is dominated by incoherent, high order contributions. The results offer additional insight into the dynamics of the dissociation of nitric acid through the S{sub 3} (2 {sup 1}A{sup '}) excited state, resolving an inconsistency in previously reported angular distributions, and pointing the way to future studies of the angular momentum polarization.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
The thin section rock physics: Modeling and measurement of seismic wave velocity on the slice of carbonates
This paper discusses a new approach for investigating the seismic wave velocity of rock, specifically carbonates, as affected by their pore structures. While the conventional routine of seismic velocity measurement highly depends on the extensive laboratory experiment, the proposed approach utilizes the digital rock physics view which lies on the numerical experiment. Thus, instead of using core sample, we use the thin section image of carbonate rock to measure the effective seismic wave velocity when travelling on it. In the numerical experiment, thin section images act as the medium on which wave propagation will be simulated. For the modeling, an advanced technique based on artificial neural network was employed for building the velocity and density profile, replacing image's RGB pixel value with the seismic velocity and density of each rock constituent. Then, ultrasonic wave was simulated to propagate in the thin section image by using finite difference time domain method, based on assumption of an acoustic-isotropic medium. Effective velocities were drawn from the recorded signal and being compared to the velocity modeling from Wyllie time average model and Kuster-Toksoz rock physics model. To perform the modeling, image analysis routines were undertaken for quantifying the pore aspect ratio that is assumed to represent the rocks pore structure. In addition, porosity and mineral fraction required for velocity modeling were also quantified by using integrated neural network and image analysis technique. It was found that the Kuster-Toksoz gives the closer prediction to the measured velocity as compared to the Wyllie time average model. We also conclude that Wyllie time average that does not incorporate the pore structure parameter deviates significantly for samples having more than 40% porosity. Utilizing this approach we found a good agreement between numerical experiment and theoretically derived rock physics model for estimating the effective seismic wave velocity of rock.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Slicing Newton spheres with a two-camera 3D imaging system
We demonstrate a simple approach to achieve three-dimensional ion momentum imaging. The method employs two complementary metal–oxide–semiconductor cameras in addition to a standard microchannel plates/phosphor screen imaging detector. The two cameras are timed to measure the decay of luminescence excited by ion hits to extract the time of flight. The achieved time resolution is better than 10 ns, which is mainly limited by camera jitters. A better than 5 ns resolution can be achieved when the jitter is suppressed.
Chemistry↗
MixPI: Mixed-time slicing path integral software for quantized molecular dynamics simulations
We introduce the MixPI software to implement path integral molecular dynamics (PIMD) simulations for the study of condensed phase systems where nuclear quantum effects (NQEs) are important. In contrast to existing PIMD simulation software, MixPI enables the implementation of mixed quantum–classical path integral simulations where only a subset of system degrees of freedom (dofs) are treated quantum mechanically in an extended phase space while the remaining dofs are described classically. We expect this software to be particularly useful for simulations of electron and proton transfer in condensed phase systems, as well as for the study of biological and material systems where only a handful of dofs contribute significantly to the observed NQEs. We demonstrate the use of MixPI in two different systems. The first is a simple water model where we implement a set of mixed quantum–classical simulations to compute average energy and radial distribution functions. We use these simulations to benchmark the effectiveness of MixPI and to demonstrate how it enables systematic investigation into the origin of observed NQEs. We then compute radial distribution functions for a system where MixPI is essential: a solvated metal (M 2+ ) cation described using an explicit quantized electron localized on an M 3+ ion in water.
chemical physics↗
Near-infrared nanosensors enable optical imaging of oxytocin with selectivity over vasopressin in acute mouse brain slices
Oxytocin plays a critical role in regulating social behaviors, yet our understanding of its function in both neurological health and disease remains incomplete. Real-time oxytocin imaging probes with spatiotemporal resolution relevant to its endogenous signaling are required to fully elucidate oxytocin’s role in the brain. Herein, we describe a near-infrared oxytocin nanosensor (nIROXT), a synthetic probe capable of imaging oxytocin in the brain without interference from its structural analogue, vasopressin. nIROXT leverages the inherent tissue-transparent fluorescence of single-walled carbon nanotubes (SWCNT) and the molecular recognition capacity of an oxytocin receptor peptide fragment to selectively and reversibly image oxytocin. We employ these nanosensors to monitor electrically stimulated oxytocin release in brain tissue, revealing oxytocin release sites with a median size of 3 µm in the paraventricular nucleus of C57BL/6 mice, which putatively represents the spatial diffusion of oxytocin from its point of release. These data demonstrate that covalent SWCNT constructs, such as nIROXT, are powerful optical tools that can be leveraged to measure neuropeptide release in brain tissue.
Science & Technology - Other Topics↗
SLICING AND DICING THE MILKY WAY DISK IN THE SLOAN DIGITAL SKY SURVEY
We use the Stripe 82 proper-motion catalog of Bramich et al. to study the kinematics of Galactic disk stars in the solar neighborhood. We select samples of dwarf stars with reliable spectra and proper motions. They have cylindrical polar radii between 7 {<=} R {<=} 9 kpc, heights from the Galactic plane satisfying |z| {<=} 2 kpc, and span a range of metallicities -1.5 {<=} [Fe/H] {<=} 0. We develop a method for calculating and correcting for the halo contamination in our sample using the distribution of rotational velocities. Two Gaussians representing disk and halo populations are used to fit the radial (v{sub R} ) and vertical (v{sub z} ) velocity distributions via maximum likelihood methods. For the azimuthal velocities (v{sub {phi}}) the same technique is used, except that a skewed non-Gaussian functional form now represents the disk velocity distribution. This enables us to compute the dispersions {sigma}{sub R}, {sigma}{sub z}, {sigma}{sub {phi}}, and cross-terms (the tilt {sigma}{sub Rz} and the vertex deviation {sigma}{sub R{phi}}) of the velocity ellipsoid as a function of height and metallicity. We also investigate the rotation lag of the disk, finding that the more metal-poor stars rotate significantly slower than the metal-rich stars. These samples provide important constraints on heating mechanisms in the Galactic disk and can be used for a variety of applications. We present one such application employing the Jeans equations to provide a simple model of the potential close to the disk. Our model is in excellent agreement with others in the literature and provides an indication that the disk, rather than the halo, dominates the circular speed at the solar neighborhood. We obtain a surface mass density within 1.1 kpc of around 66 M{sub Sun} pc{sup -2} and estimate a local halo density of 0.015 M{sub Sun} pc{sup -3} = 0.57 GeV cm{sup -3}.
79 ASTRONOMY AND ASTROPHYSICS↗
SLICING THE MONOCEROS OVERDENSITY WITH SUPRIME-CAM
We derive distance, density, and metallicity distribution of the stellar Monoceros Overdensity (MO) in the outer Milky Way, based on deep imaging with the Subaru Telescope. We applied color-magnitude diagram fitting techniques in three stripes at galactic longitudes, l {approx} 130 Degree-Sign , 150 Degree-Sign , 170 Degree-Sign , and galactic latitudes, +15 Degree-Sign {<=} b {<=} +25 Degree-Sign . The MO appears as a wall of stars at a heliocentric distance of {approx}10.1 {+-} 0.5 kpc across the observed longitude range with no distance change. The MO stars are more metal-rich ([Fe/H] {approx} -1.0) than the nearby stars at the same latitude. These data are used to test three different models for the origin of the MO: a perturbed disk model, which predicts a significant drop in density adjacent to the MO that is not seen; a basic flared disk model, which can give a good match to the density profile but the MO metallicity implies the disk is too metal-rich to source the MO stars; and a tidal stream model, which, from the literature, brackets the distances and densities we derive for the MO, suggesting that a model can be found that would fully fit the MO data. Further data and modeling will be required to confirm or rule out the MO feature as a stream or as a flaring of the disk.
79 ASTRONOMY AND ASTROPHYSICS↗
Time-sliced perturbation theory for large scale structure I: general formalism
We present a new analytic approach to describe large scale structure formation in the mildly non-linear regime. The central object of the method is the time-dependent probability distribution function generating correlators of the cosmological observables at a given moment of time. Expanding the distribution function around the Gaussian weight we formulate a perturbative technique to calculate non-linear corrections to cosmological correlators, similar to the diagrammatic expansion in a three-dimensional Euclidean quantum field theory, with time playing the role of an external parameter. For the physically relevant case of cold dark matter in an Einstein-de Sitter universe, the time evolution of the distribution function can be found exactly and is encapsulated by a time-dependent coupling constant controlling the perturbative expansion. We show that all building blocks of the expansion are free from spurious infrared enhanced contributions that plague the standard cosmological perturbation theory. This paves the way towards the systematic resummation of infrared effects in large scale structure formation. We also argue that the approach proposed here provides a natural framework to account for the influence of short-scale dynamics on larger scales along the lines of effective field theory.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Simulation analysis and optimization of fresh-slice multistage free-electron lasers
Not Available
47 OTHER INSTRUMENTATION↗
Slicing Pomerons in ultraperipheral collisions using forward neutrons from nuclear breakup
We argue that measurements of forward neutrons from nuclear breakup in inclusive high energy photon-nucleus ( γ A ) scattering provide a novel way to study small- x dynamics of QCD in heavy-ion ultraperipheral collisions (UPCs). Using models for hadronic fluctuations of the real photon and neutron emission in nuclear fragmentation, we calculate the distribution over the number of evaporation neutrons produced in γ Pb collisions at the Large Hadron Collider. We show that it is correlated with the number of wounded nucleons (inelastic collisions) and, hence, can constrain the mechanism of nuclear shadowing and its x dependence. Published by the American Physical Society 2024
Physics↗
Slicing the vacuum: New accelerating mirror solutions of the dynamical Casimir effect
Radiation from accelerating mirrors in a Minkowski spacetime provides insights into the nature of horizons, black holes, and entanglement entropy. We introduce new, simple, symmetric and analytic moving mirror solutions and study their particle, energy, and entropy production. This includes an asymptotically static case with finite emission that is the black hole analog of complete evaporation. The total energy, total entropy, total particles, and spectrum are the same on both sides of the mirror. We also study its asymptotically inertial, drifting analog (which gives a black hole remnant) to explore differences in finite and infinite production.
79 ASTRONOMY AND ASTROPHYSICS↗
Sliced Basis Density Matrix Renormalization Group for Electronic Structure
Not Available
Stoudenmire, E. Miles↗
Spectrotemporal Shaping of Attosecond X-Ray Pulses with a Fresh-Slice Free-Electron Laser
We propose a scheme allowing coherent shaping, i.e., controlling both the amplitude and phase, of attosecond x-ray pulses at free-electron lasers. Here, we show that by seeding an FEL with a short coherent seed that overfills the amplification bandwidth, one can shape the Wigner function of the pulse by controlling the undulator taper profile. The examples of controllable pulse pairs and trains, as well as isolated spectrotemporally shaped pulses with very broad bandwidths are examined in detail. Existing attosecond XFELs can achieve these experimental conditions in a two-stage cascade, in which the seed is generated by a short current spike in an electron bunch and shaped in an unspoiled region within the same bunch. We experimentally demonstrate the production and control of phase-stable pulse trains using this method at the Linac Coherent Light Source II.
47 OTHER INSTRUMENTATION↗