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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Energy flow polynomials: a complete linear basis for jet substructure

We introduce the energy flow polynomials: a complete set of jet substructure observables which form a discrete linear basis for all infrared- and collinear-safe observables. Energy flow polynomials are multiparticle energy correlators with specific angular structures that are a direct consequence of infrared and collinear safety. We establish a powerful graph-theoretic representation of the energy flow polynomials which allows us to design efficient algorithms for their computation. Many common jet observables are exact linear combinations of energy flow polynomials, and we demonstrate the linear spanning nature of the energy flow basis by performing regression for several common jet observables. Using linear classification with energy flow polynomials, we achieve excellent performance on three representative jet tagging problems: quark/gluon discrimination, boosted W tagging, and boosted top tagging. Lastly, the energy flow basis provides a systematic framework for complete investigations of jet substructure using linear methods.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Heterotic instanton superpotentials from complete intersection Calabi-Yau manifolds

We study Pfaffians that appear in non-perturbative superpotential terms arising from worldsheet instantons in heterotic theories. A result by Beasley and Witten shows that these instanton contributions cancel among curves within a given homology class for Calabi-Yau manifolds that can be described as hypersurfaces or complete intersections in projective or toric ambient spaces. We provide a prescription that identifies all $\mathbb{P}$ 1 curves in certain homology classes of complete intersection Calabi-Yau manifolds in products of projective spaces (CICYs) and cross-check our results by a comparison with the genus zero Gromov-Witten invariants. We then use this construction to study instanton superpotentials on those manifolds and their quotients. We identify a non-toric quotient of a non-favorable CICY with a single genus zero curve in a certain homology class, so that a cancellation à la Beasley-Witten is not possible. In another example, we study a non-toric quotient of a favorable CICY and check that the superpotential still vanishes. From this and related examples, we conjecture that the Beasley-Witten cancellation result can be extended to toric and non-toric quotients of CICYs, but can be avoided if the CICY is non-favorable.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Complete mesocolic excision and central vascular ligation for right colon cancer: an introduction for abdominal radiologists

Objective: To provide an overview of complete mesocolic excision, along with a review of the relevant vascular anatomy and locoregional staging concepts, for abdominal radiologists. Results: Complete mesocolic excision (CME) with central vascular ligation (CVL) for colon cancer has emerged as a technique that has growing interest in surgical oncology. Specific anatomic considerations and patterns of nodal spread have thus gained clinical significance, and should be familiar to abdominal radiologists. This review article provides an overview of CME with CVL, and discusses some of the important anatomic considerations in patients with colon cancer that are relevant to radiologists. Conclusion: Knowledge of CME with CVL and the relevant anatomic and staging considerations is important for abdominal radiologists, as this surgical technique becomes increasingly utilized.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Endovascular Repair of Acute Symptomatic Pararenal Aortic Aneurysm With Three Chimney and One Periscope Graft for Complete Visceral Artery Revascularization

PurposeTo describe a modified endovascular technique for complete revascularization of visceral and renal arteries in symptomatic pararenal aortic aneurysm (PRAA).TechniqueArterial access was surgically established in both common femoral arteries (CFAs) and the left subclavian artery (LSA). Revascularization of the left renal artery, the celiac trunk, and the superior mesenteric artery was performed through one single sheath via the LSA. Suitable covered stents were put in the aortic branches but not deployed. The right renal artery was accessed over the left CFA. Due to the longitudinal extension of the presented aneurysm two stent-grafts were introduced via the right CFA. After deploying the aortic stent-grafts, all covered stents in the side branches were deployed consecutively with a minimum overlap of 5 mm over the cranial and caudal stent-graft edges. Simultaneous ballooning was performed to fully expand all stent-grafts and warranty patency. Conclusion: This is the first report in the literature of chimney grafting in PRAA for complete revascularization of visceral and renal branches by using more than two covered stents introduced from one side through one single sheath. However this technique is modified, it should be used only in bailout situations when branched stent-grafts are not available and/or surgery is not suitable.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Combined Pharmacomechanical Thrombolysis of Complete Portomesenteric Thrombosis in a Liver Transplant Recipient

Treatment options for portomesenteric venous thrombosis range from anticoagulation to surgery, depending on chronicity, severity of symptoms, extent of thrombosis, and the availability of local expertise. For acute and subacute cases, a variety of endovascular options have been described in limited published series and case reports, including thrombolysis and mechanical thrombectomy. We report what is to our knowledge the first case in which the Trellis pharmacomechanical thrombolysis device was used successfully to treat complete acute thrombosis of the entire superior mesenteric vein and the entire portal vein with extension into all segmental intrahepatic portal branches in a young adult after liver transplantation. This device, coupled with adjunctive techniques using balloon catheters, facilitated complete restoration of flow, resulting in graft salvage and long-term patency.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Percutaneous Femoropopliteal Recanalization Using a Completely Transpedal/Transtibial Approach

PurposeTo report preliminary experience with femoropopliteal revascularization using a completely transpedal/transtibial approach.Materials and MethodsThree patients with Rutherford 3–4 disease underwent revascularization of TASC C/D lesions using a pedal/tibial artery as the only site of arterial access.ResultsOne patient with a chronic superficial femoral artery occlusion had continuity achieved to the common femoral artery using a dedicated reentry device and stenting; in a second patient, an occluded popliteal artery stent was successfully revised with an endograft; and in a third patient with morbid obesity, a chronic SFA occlusion was successfully stented. All patients experienced complete resolution of presenting symptoms; no puncture site complications were seen.ConclusionsUse of a pedal/tibial approach as the sole site of arterial access may become an important access technique for femoropopliteal revascularization when patients have limited femoral access options.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

A novel low-rank matrix completion approach to estimate missing entries in Euclidean distance matrix

A Euclidean distance matrix (EDM) is a table of distance-square between points on a k-dimensional Euclidean space, with applications in many fields (e.g., engineering, geodesy, economics, genetics, biochemistry, and psychology). A problem that often arises is the absence (or uncertainty) of some EDM elements. In many situations, only a subset of all pairwise distances is available and it is desired to have some procedure to estimate the missing distances. In this paper, we address the problem of missing data in EDM through low-rank matrix completion techniques. We exploit the fact that the rank of a EDM is at most k+2 and does not depend on the number of points, which is, in general, much bigger then k. We use a singular value decomposition approach that considers the rank of the matrix to be completed and computes, in each iteration, a parameter that controls the convergence of the method. After performing a number of computational experiments, we could observe that our proposal was able to recover, with high precision, random EDMs with more than 1000 points and up to 98% of missing data in few minutes. In addition, our method required a smaller number of iterations when compared to other competitive state-of-art technique.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

An evaluation of methodology to determine algal genome completeness

The advancement of sequencing technologies has resulted in a rapid expansion of genome sequencing. One challenge in processing and analyzing this abundance of genomics data is development and application of tools to accurately assess the quality of novel genomes. The quality of a given genome assembly is commonly assessed using the presence of conserved orthologs. However, the applicability and accuracy of identifying conserved orthologs applied to algal genome assemblies, which are uniquely diverse, is unclear. Here, in this study, we analyze the utility of a genome content assessment tool, Benchmarking Universal Single-Copy Orthologs (BUSCO), to evaluate algal genome assembly completeness. We find that Chlorophyta and Stramenopile BUSCO databases are effective tools to analyze genome completeness of these lineages. For other lineages, the Eukaryota database should be utilized until additional lineage-specific databases are developed. Based on these results, suggested best practices for current usage and necessary future improvements are provided.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Exact two-point resistance, and the simple random walk on the complete graph minus N edges

An analytical approach is developed to obtain the exact expressions for the two-point resistance and the total effective resistance of the complete graph minus N edges of the opposite vertices. These expressions are written in terms of certain numbers that we introduce, which we call the Bejaia and the Pisa numbers; these numbers are the natural generalizations of the bisected Fibonacci and Lucas numbers. The correspondence between random walks and the resistor networks is then used to obtain the exact expressions for the first passage and mean first passage times on this graph. - Highlights: Black-Right-Pointing-Pointer We obtain exact formulas for the two-point resistance of the complete graph minus N edges. Black-Right-Pointing-Pointer We obtain also the total effective resistance of this graph. Black-Right-Pointing-Pointer We modified Schwatt's formula on trigonometrical power sum to suit our computations. Black-Right-Pointing-Pointer We introduced the generalized bisected Fibonacci and Lucas numbers: the Bejaia and the Pisa numbers. Black-Right-Pointing-Pointer The first passage and mean first passage times of the random walks have exact expressions.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Kinetic model development and Bayesian uncertainty quantification for the complete reduction of Fe-based oxygen carriers with CH 4 , CO, and H 2 for chemical looping combustion

In this work, three kinetic models are developed and calibrated for the complete multi-step reduction of an Fe-based oxygen carrier (OC) particle with CH 4 , CO, and H 2 , using data from thermogravimetric analysis. The complete reduction rate profiles exhibit complex dynamics whose trajectory is significantly different depending on the reducing gas. A Bayesian model building and parameter estimation framework is applied for simultaneous parameter and model structure uncertainty quantification. The final models show excellent agreement between model predictions and calibration data, as well as new data not used for calibration (for the reduction of the OC with CH 4 ). Parameter uncertainty is quantified by determining joint posterior distribution, and model structure uncertainty is addressed by incorporating Gaussian process stochastic functions (represented by Bayesian smoothing splines) into the kinetic models. The final kinetic models with discrepancy functions are readily employable in equation-oriented simulation and optimization platforms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Structural impact of complete CpG methylation within target DNA on specific complex formation of the inducible transcription factor Egr-1

The inducible transcription factor Egr–1 binds specifically to 9–bp target sequences containing two CpG sites that can potentially be methylated at four cytosine bases. Although it appears that complete CpG methylation would make an unfavorable steric clash in the previous crystal structures of the complexes with unmethylated or partially methylated DNA, our affinity data suggest that DNA recognition by Egr–1 is insensitive to CpG methylation. We have determined, at a 1.4–Å resolution, the crystal structure of the Egr–1 zinc–finger complex with completely methylated target DNA. In conclusion, structural comparison of the three different methylation states reveals why Egr–1 can recognize the target sequences regardless of CpG methylation.

5-methylcytosine↗
DOE OSTI2023

Robust Adaptive Control for Large-scale Inverter-based Resources with Partial and Complete Loss of Inverters

This article proposes an approach to address the current and the aggregated active power control challenge for large-scale inverter-based resources subjected to partially or completely loss of inverters and grid voltage variations. To address this problem, a distributed active power mechanism is proposed which generates desired inverters current. Then an adaptive mechanism distributes the voltage control input automatically between inverters in response to the partial or complete loss of inverters. An L2-gain-based controller is designed for each inverter to track the desired current and rejects the grid voltage disturbance. Here, simulation results show a significant robust tracking for collective active power and current.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

Scaling the impacts of pore-scale characteristics on unstable supercritical CO 2 -water drainage using a complete capillary number

Geological carbon storage in deep aquifers involves displacement of resident brine by supercritical CO 2 (scCO 2 ), which is an unstable drainage process caused by the invasion of less viscous scCO 2 . The unstable drainage is greatly complicated by aquifer heterogeneity and anisotropy and regarded as one of the key factors accounting for the uncertainty in storage capacity estimates. The impacts of pore-scale characteristics on the unstable drainage remain poorly understood. In this study, scCO 2 drainage experiments were conducted at 40 °C and 9 MPa using a homogeneous elliptical micromodel with low or high anisotropy, a homogeneous/isotropic hexagonal micromodel, and a heterogeneous sandstone-analog micromodel. Each initially water-saturated micromodel was invaded by scCO 2 at different rates with logC a (the capillary number) ranging from -7.6 to -4.4, and scCO 2 /water images were obtained. The measured CO 2 saturations in these centimeter-scale micromodels vary considerably from 0.08 to 0.93 depending on the pore-scale characteristics and capillary number. It was also observed that scCO 2 drainage follows the classic flow-regime transition from capillary fingering through crossover to viscous fingering for either of the low-anisotropy elliptical and heterogeneous micromodels, but with disparate crossover zones. The crossover zones of scCO 2 saturation were then unified with the minimum scCO 2 saturation occurring at logC$_a^*$ = -4.0 using the complete capillary number (C$_a^*$)that considers pore characteristics. For the hexagonal and the high-anisotropy elliptical micromodels, a monotonic increase in scCO 2 saturation with increasing C$_a^*$ (without crossover) was observed. It appears that the complete capillary number is more appropriate than the classic capillary number when characterizing flow regimes and CO 2 saturation in different pore networks.

58 GEOSCIENCES↗
DOE OSTI2011

Is Radiotherapy an Option for Early Breast Cancers With Complete Clinical Response After Neoadjuvant Chemotherapy?

Purpose: To determine whether the exclusive use of radiotherapy (ERT) could be a treatment option after complete clinical response (cCR) to neoadjuvant chemotherapy (NCT) for early breast cancer (EBC). Methods and Materials: Between 1985 and 1999, 1,477 patients received NCT for EBC considered too large for primary conservative surgery. Of 165 patients with cCR, 65 patients were treated with breast surgery (with radiotherapy) and 100 patients were treated with ERT. Results: The two groups were comparable in terms of baseline characteristics, except for larger initial tumor sizes in the ERT group. There were no significant differences in overall, disease-free and metastasis-free survival rates. Five-year and 10-year overall survival rates were 91% and 77% in the no-surgery group and 82% and 79% in the surgery group, respectively (p = 0.9). However, a nonsignificant trend toward higher locoregional recurrence rates (LRR) was observed in the no-surgery group (31% vs. 17% at 10 years; p = 0.06). In patients with complete responses on mammography and/or ultrasound, LRR were not significantly different (p = 0.45, 10-year LRR: 21% in surgery vs. 26% in ERT). No significant differences were observed in terms of the rate of cutaneous, cardiac, or pulmonary toxicities. Conclusions: Surgery is a key component of locoregional treatment for breast cancers that achieved cCR to NCT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Prognostic Value of p16 Status on the Development of a Complete Response in Involved Oropharynx Cancer Neck Nodes After Cisplatin-Based Chemoradiation: A Secondary Analysis of NRG Oncology RTOG 0129

Purpose: To determine the relationship between p16 status and the regional response of patients with node-positive oropharynx cancer treated on NRG Oncology RTOG 0129. Methods and Materials: Patients with N1-N3 oropharynx cancer and known p16 status who underwent treatment on RTOG 0129 were analyzed. Pathologic complete response (pCR) rates in patients treated with a postchemoradiation neck dissection (with p16-positive or p16-negative cancer) were compared by Fisher exact test. Patients managed expectantly were compared with those treated with a neck dissection. Results: Ninety-nine (34%) of 292 patients with node-positive oropharynx cancer and known p16 status underwent a posttreatment neck dissection (p16-positive: n=69; p16-negative: n=30). The remaining 193 patients with malignant lymphadenopathy at diagnosis were observed. Neck dissection was performed a median of 70 (range, 17-169) days after completion of chemoradiation. Neither the pretreatment nodal stage (P=.71) nor the postradiation, pre-neck dissection clinical/radiographic neck assessment (P=.42) differed by p16 status. A pCR was more common among p16-positive patients (78%) than p16-negative patients (53%, P=.02) and was associated with a reduced incidence of local–regional failure (hazard ratio 0.33, P=.003). On multivariate analysis of local–regional failure, a test for interaction between pCR and p16 status was not significant (P=.37). One-hundred ninety-three (66%) of 292 of initially node-positive patients were managed without a posttreatment neck dissection. Development of a clinical (cCR) was not significantly influenced by p16-status (P=.42). Observed patients with a clinical nodal CR had disease control outcomes similar to those in patients with a pCR neck dissection. Conclusions: Patients with p16-positive tumors had significantly higher pCR and locoregional control rates than those with p16-negative tumors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Application of stochastic Galerkin FEM to the complete electrode model of electrical impedance tomography

The aim of electrical impedance tomography is to determine the internal conductivity distribution of some physical body from boundary measurements of current and voltage. The most accurate forward model for impedance tomography is the complete electrode model, which consists of the conductivity equation coupled with boundary conditions that take into account the electrode shapes and the contact resistances at the corresponding interfaces. If the reconstruction task of impedance tomography is recast as a Bayesian inference problem, it is essential to be able to solve the complete electrode model forward problem with the conductivity and the contact resistances treated as a random field and random variables, respectively. In this work, we apply a stochastic Galerkin finite element method to the ensuing elliptic stochastic boundary value problem and compare the results with Monte Carlo simulations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Permutation-adapted complete and independent basis for atomic cluster expansion descriptors

Atomic cluster expansion (ACE) methods provide a systematic way to describe particle local environments of arbitrary body order. For practical applications it is often required that the basis of cluster functions be symmetrized with respect to rotations and permutations. Existing methodologies yield sets of symmetrized functions that are over-complete. These methodologies thus require an additional numerical procedure, such as singular value decomposition (SVD), to eliminate redundant functions. In this work, it is shown that analytical linear relationships for subsets of cluster functions may be derived using recursion and permutation properties of generalized Wigner symbols. From these relationships, subsets (blocks) of cluster functions can be selected such that, within each block, functions are guaranteed to be linearly independent. It is conjectured that this block-wise independent set of permutation-adapted rotation and permutation invariant (PA-RPI) functions forms a complete, independent basis for ACE. Along with the first analytical proofs of block-wise linear dependence of ACE cluster functions and other theoretical arguments, numerical results are offered to demonstrate this. The utility of the method is demonstrated in the development of an ACE interatomic potential for tantalum. Using the new basis functions in combination with Bayesian compressive sensing sparse regression, some high degree descriptors are observed to persist and help achieve high-accuracy models.

Angular momentum↗
DOE OSTI2025

Numerical schemes for 3-wave kinetic equations: A complete treatment of the collision operator

In our previous work Walton and Tran (2023), numerical schemes for a simplified version of 3-wave kinetic equations, in which only the simple forward-cascade terms of the collision operators are kept, have been successfully designed, especially to capture the long time dynamics of the equation given the multiple blow-up time phenomenon. In this second work in the series, we propose numerical treatments for the complete 3-wave kinetic equations, in which the complete, much more complicated collision operators are fully considered based on a novel conservative form of the equation. Here we then derive an implicit finite volume scheme to solve the equation. The new discretization uses an adaptive time-stepping method which allows for the simulations to be carried to very long times. Our computed solutions are compared with previously derived long-time asymptotic estimates for the decay rate of total energy of time-dependent solutions of 3-wave kinetic equations and found to be in excellent agreement.

97 MATHEMATICS AND COMPUTING↗