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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Temporal Nodal Regression and Regional Control After Primary Radiation Therapy for N2-N3 Head-and-Neck Cancer Stratified by HPV Status

Purpose: To compare the temporal lymph node (LN) regression and regional control (RC) after primary chemoradiation therapy/radiation therapy in human papillomavirus-related [HPV(+)] versus human papillomavirus-unrelated [HPV(−)] head-and-neck cancer (HNC). Methods and Materials: All cases of N2-N3 HNC treated with radiation therapy/chemoradiation therapy between 2003 and 2009 were reviewed. Human papillomavirus status was ascertained by p16 staining on all available oropharyngeal cancers. Larynx/hypopharynx cancers were considered HPV(−). Initial radiologic complete nodal response (CR) (≤1.0 cm 8-12 weeks after treatment), ultimate LN resolution, and RC were compared between HPV(+) and HPV(−) HNC. Multivariate analysis identified outcome predictors. Results: A total of 257 HPV(+) and 236 HPV(−) HNCs were identified. The initial LN size was larger (mean, 2.9 cm vs 2.5 cm; P<.01) with a higher proportion of cystic LNs (38% vs 6%, P<.01) in HPV(+) versus HPV(−) HNC. CR was achieved is 125 HPV(+) HNCs (49%) and 129 HPV(−) HNCs (55%) (P=.18). The mean post treatment largest LN was 36% of the original size in the HPV(+) group and 41% in the HPV(−) group (P<.01). The actuarial LN resolution was similar in the HPV(+) and HPV(−) groups at 12 weeks (42% and 43%, respectively), but it was higher in the HPV(+) group than in the HPV(−) group at 36 weeks (90% vs 77%, P<.01). The median follow-up period was 3.6 years. The 3-year RC rate was higher in the HPV(−) CR cases versus non-CR cases (92% vs 63%, P<.01) but was not different in the HPV(+) CR cases versus non-CR cases (98% vs 92%, P=.14). On multivariate analysis, HPV(+) status predicted ultimate LN resolution (odds ratio, 1.4 [95% confidence interval, 1.1-1.7]; P<.01) and RC (hazard ratio, 0.3 [95% confidence interval 0.2-0.6]; P<.01). Conclusions: HPV(+) LNs involute more quickly than HPV(−) LNs but undergo a more prolonged process to eventual CR beyond the time of initial assessment at 8 to 12 weeks after treatment. Post radiation neck dissection is advisable for all non-CR HPV(−)/non-CR N3 HPV(+) cases, but it may be avoided for selected non-CR N2 HPV(+) cases with a significant LN involution if they can undergo continued imaging surveillance. The role of positron emission tomography for response assessment should be investigated.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

The algebra of dual -1 Hahn polynomials and the Clebsch-Gordan problem of sl{sub -1}(2)

The algebra H of the dual -1 Hahn polynomials is derived and shown to arise in the Clebsch-Gordan problem of sl{sub -1}(2). The dual -1 Hahn polynomials are the bispectral polynomials of a discrete argument obtained from the q{yields}-1 limit of the dual q-Hahn polynomials. The Hopf algebra sl{sub -1}(2) has four generators including an involution, it is also a q{yields}-1 limit of the quantum algebra sl{sub q}(2) and furthermore, the dynamical algebra of the parabose oscillator. The algebra H, a two-parameter generalization of u(2) with an involution as additional generator, is first derived from the recurrence relation of the -1 Hahn polynomials. It is then shown that H can be realized in terms of the generators of two added sl{sub -1}(2) algebras, so that the Clebsch-Gordan coefficients of sl{sub -1}(2) are dual -1 Hahn polynomials. An irreducible representation of H involving five-diagonal matrices and connected to the difference equation of the dual -1 Hahn polynomials is constructed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Hardened Novikov Gears as the Last Stage of General-Purpose Gear Systems

The creation of general-purpose gear systems with hardened Novikov gears of relatively low precision is considered. By solving three-dimensional elastic-contact problems and modeling, the replacement of expensive high-precision involute gears in the final stage of general-purpose gear systems by less expensive hardened Novikov gears of lower precision is shown to be expedient. Preliminary calculations of prospective high-precision Novikov gears are presented. They offer considerable advantages over their involute counterparts.

42 ENGINEERING↗
DOE OSTI2021

As-Built Simulation of the High Flux Isotope Reactor

The Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) is an 85 MWt flux trap-type research reactor that supports key research missions, including isotope production, materials irradiation, and neutron scattering. The core consists of an inner and an outer fuel element containing 171 and 369 involute-shaped plates, respectively. The thin fuel plates consist of a U 3 O 8 -Al dispersion fuel (highly enriched), an aluminum-based filler, and aluminum cladding. The fuel meat thickness is varied across the width of the involute plate to reduce thermal flux peaks at the radial edges of the fuel elements. Some deviation from the designed fuel meat shaping is allowed during manufacturing. A homogeneity scan of each fuel plate checks for potential anomalies in the fuel distribution by scanning the surface of the plate and comparing the attenuation of the beam to calibration standards. While typical HFIR simulations use homogenized fuel regions, explicit models of the plates were developed under the Low-Enriched Uranium Conversion Program. These explicit models typically include one inner and one outer fuel plate with nominal fuel distributions, and then the plates are duplicated to fill the space of the corresponding fuel element. Therefore, data extracted from these simulations are limited to azimuthally averaged quantities. To determine the reactivity and physics impacts of an as-built outer fuel element and generate azimuthally dependent data in the element, 369 unique fuel plate models were generated and positioned. This model generates the three-dimensional (i.e., radial–axial–azimuthal) plate power profile, where the azimuthal profile is impacted by features within the adjacent control element region and beryllium reflector. For an as-built model of the outer fuel element, plate-specific homogeneity data, 235 U loading, enrichment, and channel thickness measurements were translated into the model, yielding a much more varied azimuthal power profile encompassed by uncertainty factors in analyses. These models were run with the ORNL-TN and Shift Monte Carlo tools, and they contained upwards of 500,000 cells and 100,000 unique tallies.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2015

Optimization of Depletion Modeling and Simulation for the High Flux Isotope Reactor

Monte Carlo based depletion tools used for the high-fidelity modeling and simulation of the High Flux Isotope Reactor (HFIR) come at a great computational cost; finding sufficient approximations is necessary to make the use of these tools feasible. The optimization of the neutronics and depletion model for the HFIR is based on two factors: (i) the explicit representation of the involute fuel plates with sets of polyhedra and (ii) the treatment of depletion mixtures and control element position during depletion calculations. A very fine representation (i.e., more polyhedra in the involute plate approximation) does not significantly improve simulation accuracy. The recommended representation closely represents the physical plates and ensures sufficient fidelity in regions with high flux gradients. Including the fissile targets in the central flux trap of the reactor as depletion mixtures has the greatest effect on the calculated cycle length, while localized effects (e.g., the burnup of specific isotopes or the power distribution evolution over the cycle) are more noticeable consequences of including a critical control element search or depleting burnable absorbers outside the fuel region.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2018

An uplifting discussion of T-duality

It is well known that string theory has a T-duality symmetry relating circle compactifications of large and small radius. This symmetry plays a foundational role in string theory. We note here that while T-duality is order two acting on the moduli space of compactifications, it is order four in its action on the conformal field theory state space. More generally, involutions in the Weyl group W (G) which act at points of enhanced G symmetry have canonical lifts to order four elements of G, a phenomenon first investigated by J. Tits in the mathematical literature on Lie groups and generalized here to conformal field theory. This simple fact has a number of interesting consequences. One consequence is a reevaluation of a mod two condition appearing in asymmetric orbifold constructions. We also briefly discuss the implications for the idea that T-duality and its generalizations should be thought of as discrete gauge symmetries in spacetime.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Heterotic backgrounds via generalised geometry: moment maps and moduli

We describe the geometry of generic heterotic backgrounds preserving minimal supersymmetry in four dimensions using the language of generalised geometry. They are characterised by an SU(3) × Spin(6 + n) structure within O(6, 6 + n) x $\mathbb{R}$ + generalised geometry. Supersymmetry of the background is encoded in the existence of an involutive subbundle of the generalised tangent bundle and the vanishing of a moment map for the action of diffeomorphisms and gauge symmetries. We give both the superpotential and the Kähler potential for a generic background, showing that the latter defines a natural Hitchin functional for heterotic geometries. Intriguingly, this formulation suggests new connections to geometric invariant theory and an extended notion of stability. Finally we show that the analysis of infinitesimal deformations of these geometric structures naturally reproduces the known cohomologies that count the massless moduli of supersymmetric heterotic backgrounds.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Fricke S-duality in CHL models

In this study, we consider four dimensional CHL models with sixteen spacetime supersymmetries obtained from orbifolds of type IIA superstring on K3×T 2 by a Z N symmetry acting (possibly) non-geometrically on K3. We show that most of these models (in particular, for geometric symmetries) are self-dual under a weak-strong duality acting on the heterotic axio-dilaton modulus S by a “Fricke involution” S → -1/NS. This is a novel symmetry of CHL models that lies outside of the standard SL(2,Z)-symmetry of the parent theory, heterotic strings on T 6 . For self-dual models this implies that the lattice of purely electric charges is N-modular, i.e. isometric to its dual up to a rescaling of its quadratic form by N. We verify this prediction by determining the lattices of electric and magnetic charges in all relevant examples. We also calculate certain BPS-saturated couplings and verify that they are invariant under the Fricke S-duality. For CHL models that are not self-dual, the strong coupling limit is dual to type IIA compactified on T 6 /Z N , for some Z N -symmetry preserving half of the spacetime supersymmetries.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Radiofrequency Ablation of Large Renal Angiomyolipoma: Median-Term Follow-Up

Purpose. To study the feasibility of percutaneous radiofrequency ablation (RFA) of large angiomyolipomas (AMLs) using saline-cooled electrodes. Materials and Methods. Institutional Review Board approval for the study was received. Four patients (all female, age range 33-67 years) with large AMLs (maximal axis 6.1-32.4 cm) not suitable for embolotherapy or surgery consented to a trial of RFA. Procedures were performed under computerized tomographic guidance using 14G saline-infused electrodes. Two ablations (diameter 4-7 cm) were undertaken in each patient. Variables studied were technical success, treatment safety, alteration of tumor consistency, tumor size, effect on renal function, and medium-term freedom from haemorrhage. Results. All four patients underwent successful RFA without any intraprocedural complications. There has been no haemorrhage, or new renal specific symptom, during a minimum 48-month period, and normal renal function has been normal. On follow-up radiological imaging, the tumors have become fattier with involution of the soft-tissue elements (soft tissue-to-total tumor ratio decreased mean [range] of 0.26 [0.14-0.48] to 0.17 [0.04-0.34] U; p = 0.04 [paired Student t test]). Further evidence of treatment effect was the development of a capsule around the ablation zone, but there was no change in overall tumor volume (mean [range] 1,120 [118-2,845] to 1150 [90-3,013] ml; p = 1 [paired Student t test]). Conclusion. RFA of large AMLs is technically feasible using saline-infused electrodes. The soft-tissue elements decreased in volume; the tumors become fattier; and there has been no renal haemorrhage during a 48-month period.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Imaging Features of Radiofrequency Ablation with Heat-Deployed Liposomal Doxorubicin in Hepatic Tumors

IntroductionThe imaging features of unresectable hepatic malignancies in patients who underwent radiofrequency ablation (RFA) in combination with lyso-thermosensitive liposomal doxorubicin (LTLD) were determined.Materials and MethodsA phase I dose escalation study combining RFA with LTLD was performed with peri- and post- procedural CT and MRI. Imaging features were analyzed and measured in terms of ablative zone size and surrounding penumbra size. The dynamic imaging appearance was described qualitatively immediately following the procedure and at 1-month follow-up. The control group receiving liver RFA without LTLD was compared to the study group in terms of imaging features and post-ablative zone size dynamics at follow-up.ResultsPost-treatment scans of hepatic lesions treated with RFA and LTLD have distinctive imaging characteristics when compared to those treated with RFA alone. The addition of LTLD resulted in a regular or smooth enhancing rim on T1W MRI which often correlated with increased attenuation on CT. The LTLD-treated ablation zones were stable or enlarged at follow-up four weeks later in 69 % of study subjects as opposed to conventional RFA where the ablation zone underwent involution compared to imaging acquired immediately after the procedure.ConclusionThe imaging features following RFA with LTLD were different from those after standard RFA and can mimic residual or recurrent tumor. Knowledge of the subtle findings between the two groups can help avoid misinterpretation and proper identification of treatment failure in this setting. Increased size of the LTLD-treated ablation zone after RFA suggests the ongoing drug-induced biological effects.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Characteristically Closed Domains for First Order Strictly Hyperbolic Systems in the Plane

We consider a first order strictly hyperbolic system of n equations with constant coefficients in a bounded domain. It is assumed that the domain is strictly convex relative to characteristics, so that the projection along each characteristic is an involution having two fixed singular points. The natural statement of boundary value problems for such systems requires that singular points go to singular points under such transformations. We present a necessary and sufficient condition for the existence of such domains, called characteristically closed.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Normalizers of Elementary Overgroups of Ep(2, A)

Let A be an involution ring, e{sub 1}, . . . , e{sub n} be a full system of Hermitian idempotents in A, let every ei generate A as a two-sided ideal, and 2 ∈ A{sup ∗}. In this paper, the normalizers of the groups Ep(2,A) · E(2,A, I) are calculated under natural assumptions on A, where Ep(2,A) denotes the elementary symplectic group, E(2,A, I) stands for the elementary subgroup of level I.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Double Cosets of Stabilizers of Totally Isotropic Subspaces in a Special Unitary Group. I

Let D be a division algebra with a fixed involution, and let V be the corresponding unitary space over D with T -condition (see N. Bourbaki, Algèbre). For a pair of totally isotropic subspaces u, v ≤ V, the double cosets P{sub u}γP{sub v} of their stabilizers P{sub u}, P{sub v} in Γ = SU(V ) are considered. A description of the cosets P{sub u}γP{sub v} in terms of the intersection distance d{sub in}(u, γ(v)) and the Witt index of u + γ(v) is given.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Integrable coupled Liénard-type systems with balanced loss and gain

A Hamiltonian formulation of generic many-particle systems with space-dependent balanced loss and gain coefficients is presented. It is shown that the balancing of loss and gain necessarily occurs in a pair-wise fashion. Further, using a suitable choice of co-ordinates, the Hamiltonian can always be reformulated as a many-particle system in the background of a pseudo-Euclidean metric and subjected to an analogous inhomogeneous magnetic field with a functional form that is identical with space-dependent loss/gain co-efficient. The resulting equations of motion from the Hamiltonian are a system of coupled Liénard-type differential equations. Partially integrable systems are obtained for two distinct cases, namely, systems with (i) translational symmetry or (ii) rotational invariance in a pseudo-Euclidean space. A total number of m+1 integrals of motion are constructed for a system of 2m particles, which are in involution, implying that two-particle systems are completely integrable. A few exact solutions for both the cases are presented for specific choices of the potential and space-dependent gain/loss co-efficients, which include periodic stable solutions. Quantization of the system is discussed with the construction of the integrals of motion for specific choices of the potential and gain–loss coefficients. A few quasi-exactly solvable models admitting bound states in appropriate Stoke wedges are presented.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Repetitive restraint stress changes spleen immune cell subsets through glucocorticoid receptor or β-adrenergic receptor in a stage dependent manner

Highlights: • Repetitive restraint stress (RRS) changes the immune cell subsets in spleen. • RU486 reverses the changes of spleen immune cell subsets induced by 7 days of RRS. • Propranolol reverses the changes of spleen immune cell subsets induced by 21 days of RRS. Immune system is sensitive to stress. Spleen is the largest peripheral immune organ innervated with sympathetic nerves and controlled by adrenomedullary system in the body. However, the alterations and mechanism of spleen immune cell subsets caused by repetitive restraint stress (RRS) is poorly understood. In this study, we found that RRS reduced spleen index in mice, and induced an expansion of white pulp and involution of the red pulp. Meanwhile, the percentage of CD3{sup +}CD8{sup +} T lymphocytes, CD11b{sup +}F4/80{sup +} macrophages, CD11b{sup +}Ly-6G{sup −}Ly-6C{sup hi} monocytic myeloid derived suppressor cells (mMDSCs) and CD11b{sup +}Ly-6G{sup +}Ly-6C{sup int} granulocytic myeloid derived suppressor cells (gMDSCs) in spleen were significantly changed by RRS. Mechanistically, we found that the expression of norepinephrine (NE) and β-adrenergic receptor (β-AR) in spleen were up-regulated after 21 days of RRS, but not 7 days. The expression of corticosterone (CORT) and glucocorticoid receptor (GR) in spleen were up-regulated after 7 days of RRS but were lower after 21 days of RRS, even though they were still higher than that in mice without stress. By treating the stressed mice with RU486 (antagonist of GR) or propranolol (antagonist of β-AR), we demonstrated that GR was responsible for the changes of spleen induced by 7 days of RRS and β-AR was for 21 days of RRS. Our data suggest that RRS changes spleen immune cell subsets through GR or β-AR in a stage dependent manner.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

On a fully-implicit VMS-stabilized FE formulation for low Mach number compressible resistive MHD with application to MCF

This study presents the development and evaluation of a fully-implicit variational multiscale (VMS) stabilized unstructured finite element (FE) formulation for compressible magnetohydrodynamics (MHD) model, at low Mach number regime. The model describes the dynamics of a compressible conducting fluid in the low Mach number limit in the presence of electromagnetic fields and can be used to study aspects of astrophysical phenomena, important science and technology applications, and basic plasma physics phenomena. The specific applications that motivate this study are macroscopic simulations of the longer time-scale stability and disruptions of magnetic confinement fusion (MCF) devices, specifically the ITER tokamak. The discussion considers the development of the VMS FE representation, the structure of the stabilizing terms that deal with significant convective flows, the stabilization of the nearly incompressible response of the fluid flow, and the stabilization of the constraint that enforces the solenoidal involution on the magnetic field. The nonlinear discretized system is solved with scalable preconditioned Newton–Krylov iterative methods, which employs a multiphysics block preconditioning method based on approximate block factorizations and Schur complements. The study presents an evaluation of the VMS method on a 2D cartesian tearing mode instability, and illustrates the scalability of the solvers on MCF relevant problems. A set of results are also presented for longer time-scale stability and disruptions for the ITER tokamak. These include a vertical displacement event (VDE), and a (1,1) internal kink mode. Here, the formulation is demonstrated to be scalable and also reasonably robust with respect to the Lundquist number scaling.

42 ENGINEERING↗
DOE OSTI2013

Knockout of the aryl hydrocarbon receptor results in distinct hepatic and renal phenotypes in rats and mice

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor which plays a role in the development of multiple tissues and is activated by a large number of ligands, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In order to examine the roles of the AHR in both normal biological development and response to environmental chemicals, an AHR knockout (AHR-KO) rat model was created and compared with an existing AHR-KO mouse. AHR-KO rats harboring either 2-bp or 29-bp deletion mutation in exon 2 of the AHR were created on the Sprague–Dawley genetic background using zinc-finger nuclease (ZFN) technology. Rats harboring either mutation type lacked expression of AHR protein in the liver. AHR-KO rats were also insensitive to thymic involution, increased hepatic weight and the induction of AHR-responsive genes (Cyp1a1, Cyp1a2, Cyp1b1, Ahrr) following acute exposure to 25 μg/kg TCDD. AHR-KO rats had lower basal expression of transcripts for these genes and also accumulated ∼ 30–45-fold less TCDD in the liver at 7 days post-exposure. In untreated animals, AHR-KO mice, but not AHR-KO rats, had alterations in serum analytes indicative of compromised hepatic function, patent ductus venosus of the liver and persistent hyaloid arteries in the eye. AHR-KO rats, but not AHR-KO mice, displayed pathological alterations to the urinary tract: bilateral renal dilation (hydronephrosis), secondary medullary tubular and uroepithelial degenerative changes and bilateral ureter dilation (hydroureter). The present data indicate that the AHR may play significantly different roles in tissue development and homeostasis and toxicity across rodent species. - Highlights: • An AHR knockout rat was generated on a Sprague–Dawley outbred background. • AHR-KO rats lack expression of AHR protein. • AHR-KO rats are insensitive to TCDD-mediated effects. • Data suggests difference in the role of AHR in tissue development of rats and mice. • Abnormalities in vascular development are observed in AHR-KO mouse, but not rat. • Renal pathology is observed in AHR-KO rat, but not mouse.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

A novel conditional formulation of the Vlasov–Ampère equations: a conservative, positivity, asymptotic and Gauss law preserving scheme

We propose a novel reformulation of the Vlasov–Ampère equations for plasmas that reveals discrete symmetries that enables simultaneous conservation of mass, momentum and energy; preservation of Gauss’s law; positivity of the distribution function; and consistency with quasi-neutral asymptotics. The approach employs variable and coordinate transformations to yield a coupled system comprising a modified Vlasov equation and associated moment–field equations. The modified Vlasov equation advances a conditional distribution function that excludes mass, momentum and energy densities, which are instead evolved through moment equations enforcing the relevant symmetries, conservation laws and involution constraints. This reformulation aligns naturally with a recent slow-manifold reduction technique, which separates fast electron time scales and simplifies the treatment of the quasi-neutral limit within the reduced moment–field subsystem. Using this framework, we develop a numerical method for the reduced 1D1V subsystem that, for the first time in the literature, satisfies all key physical constraints while maintaining a quasi-neutral asymptotic behaviour. The advantages of the method are demonstrated on canonical electrostatic test problems, including the multiscale ion acoustic shock wave.

1D1V↗