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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

The analytic two-loop soft function for leading-jet p T

We present the calculation of the two-loop soft function for the transverse momentum distribution of the leading jet produced in association with any colour-singlet system (e.g. a Higgs or a Z boson). This constitutes a central ingredient for the resummation of the above distribution as well as the jet-vetoed cross section at the next-to-next-to-next-to-leading logarithmic order, both of which play an important role in the precision physics programme at the Large Hadron Collider. The calculation is performed in soft-collinear effective theory with an appropriate regularisation of the rapidity divergences that occur in the phase-space integrals. We obtain analytic results by employing an exponential regulator and by taking a Laurent expansion in the jet radius R . All expressions are presented as supplementary material attached to this article.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Asymptotic symmetries and Weinberg’s soft photon theorem in Mink d+2

We show that Weinberg's leading soft photon theorem in massless abelian gauge theories implies the existence of an infinite-dimensional large gauge symmetry which acts non-trivially on the null boundaries ${\mathscr I}^\pm$ of $(d+2)$-dimensional Minkowski spacetime. These symmetries are parameterized by an arbitrary function $\varepsilon(x)$ of the $d$-dimensional celestial sphere living at ${\mathscr I}^\pm$. This extends the previously established equivalence between Weinberg's leading soft theorem and asymptotic symmetries from four and higher even dimensions to all higher dimensions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Soft theorems in matrix theory

We show that the Banks-Fischler-Shenker-Susskind matrix model for M-theory obeys the leading and subleading soft theorems expected from eleven-dimensional supergravity. The subleading soft theorem implies the amplitude is Lorentz symmetric. This is argued for general four point amplitudes, but only for restricted kinematics for five and higher point amplitudes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Nonviolent unitarization: basic postulates to soft quantum structure of black holes

A first-principles approach to the unitarity problem for black holes is systematically explored, based on the postulates of 1) quantum mechanics 2) the ability to approximately locally divide quantum gravitational systems into subsystems 3) correspondence with quantum field theory predictions for appropriate observers and (optionally) 4) universality of new gravitational effects. Unitarity requires interactions between the internal state of a black hole and its surroundings that have not been identified in the field theory description; correspondence with field theory indicates that these are soft. A conjectured information-theoretic result for information transfer between subsystems, partly motivated by a perturbative argument, then constrains the minimum coupling size of these interactions of the quantum atmosphere of a black hole. While large couplings are potentially astronomically observable, given this conjecture one finds that the new couplings can be exponentially small in the black hole entropy, yet achieve the information transfer rate needed for unitarization, due to the large number of black hole internal states. This provides a new possible alternative to arguments for large effects near the horizon. If universality is assumed, these couplings can be described as small, soft, state-dependent fluctuations of the metric near the black hole. As a result, open questions include that of the more fundamental basis for such an effective picture.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Single-soft emissions for amplitudes with two colored particles at three loops

We compute the three-loop correction to the universal single-soft emission current for the case of scattering amplitudes with two additional color-charged partons. We present results valid for QCD and $\mathcal{N}$ = 4 super-symmetric Yang-Mills theory. To achieve our results we develop a new integrand expansion technique for scattering amplitudes in the presence of soft emissions. Furthermore, we obtain contributions from single final-state parton matrix elements to the Higgs boson and Drell-Yan production cross section at next-to-next-to-next-to-next-to leading order (N 4 LO) in perturbative QCD in the threshold limit.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Avoiding Complications in Bone and Soft Tissue Ablation

As with percutaneous ablation of tumors in the liver, lungs, and kidneys, ablation of bone and non-visceral soft tissue tumors carries risk, primarily from collateral damage to vital structures in proximity to the target tumor. Certain risks are of particular interest when ablating bone and non-visceral soft tissue tumors, namely neural or skin injury, bowel injury, fracture, and gas embolism from damaged applicators. Ablation of large volume tumors also carries special risk. Many techniques may be employed by the interventional radiologist to minimize complications when treating tumors in the musculoskeletal system. These methods include those to depict, displace, or monitor critical structures. Thus, measures to provide thermoprotection may be active, such as careful ablation applicator placement and use of various displacement techniques, as well as passive, including employment of direct temperature, radiographic, or neurophysiologic monitoring techniques. Cementoplasty should be considered in certain skeletal locations at risk of fracture. Patients treated with large volume tumors should be monitored for renal dysfunction and properly hydrated. Finally, ablation applicators should be cautiously placed in the constrained environment of intact bone.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Basic Knowledge in Soft Tissue Sarcoma

Sarcoma is rare and heterogenous with various subtypes having a different prognostic. Desmoid is a tumour with a local aggressiveness; GIST with KIT mutation responds massively to target treatment as IMATINIB, whereas soft tissue sarcoma and leiomyosarcoma are very aggressive with poor response to systemic therapies. Interventional radiology plays an important role in the diagnosis of sarcomas with image-guided percutaneous core needle biopsy being the most commonly used biopsy technique in the diagnosis of sarcomas. Biopsy access routes discussed with the surgeon, and skin access is tattooed. Surgery is a mainstay of sarcoma treatment; the resection can be large. Indeed, resection objective is R0 because quality of surgical margins impacts local control and survival. Radiotherapy is possible in neoadjuvant or in adjuvant treatment to improve local control rate. Recently radiotherapy enhancer injected percutaneously in soft tissue sarcoma has proven benefit in increasing the rate of R0 complete surgical resection. Several studies showed better local control rate linked with post-operative radiotherapy. In patients affected by oligometastatic disease, complete surgical resection of all metastatic sites is in fact considered the primary treatment because complete remission is critical for cure. The decision making to use local therapies is complex, depends upon diverse presentations and histologies, and should always be taken in a multidisciplinary discussion. Today, percutaneous image-guided treatments with ablation technologies (radiofrequency ablation, cryotherapy, microwaves ablation) provide high rate of durable local control for small-sized malignant deposit in many organs including lung, liver and bones. Sarcoma must be managed by multimodality treatment in expert reference centres. Such management has a considerable impact on the prognosis.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Soft Magnetic Properties of Hf{sub x}Co{sub 100−x} Thin Films

Hf{sub x}Co{sub 100−x} thin films (in the atomic weight range of x = 30–36) were growth on Si (100) substrates by direct current (DC) magnetron sputtering method. Thin films produced with atomic compositions in this context depicted the amorphous structure. The films revealed soft magnetic properties and thus exhibited very low hysteresis along the hard-axis direction. Magnetic measurements indicated that Hf{sub 35}Co{sub 65} thin film has the maximum saturation magnetization (1491 emu cm{sup −3}) at 300 K. Additionally, magnetization measurements show an increase in saturation magnetization value from 981 to 1491 emu cm{sup −3} when the value of x varies between 30 and 35. The influence of varying sputtering pressure and film composition on soft magnetic properties are investigated and discussed in the present paper.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Magnetic Spectra of Soft Magnetic Composites Based on Fe-Si-Cr-B Amorphous and Carbonyl-Iron Powders

Fe–Si–Cr–B amorphous and carbonyl-iron powders insulated with phosphoric acid solution were used to prepare soft magnetic composites. The mass ratios of phosphoric acid insulation solution and the carbonyl-iron powder dependences of the magnetic spectrum, the density, and the resistivity were studied. Both the real part and the imaginary part of the core’s complex permeability increased after an initial decrease with the acid mass ratio increasing. This is similar to the variation tendency of the core’s density and opposite to the variation tendency of the core’s resistivity. The amount of the air gap, reflected by the density, was proposed to be the most important factor that has a great influence on the composite’s magnetic properties. The increase of the air gap reduced the effective demagnetizing field and the resistivity. This improved the permeability and the hysteresis loss and deteriorated the eddy-current loss. Carbonyl-iron powder addition was found to improve the moldability and the permeability of the composite based on the Fe-Si-Cr-B amorphous powder, although its loss was higher than that of the amorphous powder. All these findings can be referenced when designing an amorphous-based soft magnetic composite (SMC) core with balanced permeability, loss, and cost for high-frequency inductor within a MHz band.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Soft Communities in Similarity Space

The S{sup 1} model has been central in the development of the field of network geometry. It places nodes in a similarity space and connects them with a likelihood depending on an effective distance which combines similarity and popularity dimensions, with popularity directly related to the degrees of the nodes. The S{sup 1} model has been mainly studied in its homogeneous regime, in which angular coordinates are independently and uniformly scattered on the circle. We now investigate if the model can generate networks with targeted topological features and soft communities, that is, inhomogeneous angular distributions. To that end, hidden degrees must depend on angular coordinates, and we propose a method to estimate them. We conclude that the model can be topologically invariant with respect to the soft-community structure. Our results expand the scope of the model beyond the independent hidden variables limit and can have an important impact in the embedding of real-world networks.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Characterization of Fe-6Si Soft Magnetic Alloy Produced by Laser-Directed Energy Deposition Additive Manufacturing

Abstract Commercial electrical steels, Fe-Si alloys with < 4 wt.% Si, are inexpensive and efficient materials for electrical power conversion. Further efficiency improvements require increasing the silicon concentration to 6 wt.%, at which point the material becomes brittle and difficult to form by conventional rolling and sheet fabrication methods. Additive manufacturing stands to overcome challenges with commercial manufacturing techniques by leveraging near-net-shape fabrication. The wide array of process conditions provides additive manufacturing with increased flexibility, enabling control over the microstructure and mechanical properties. This work explores the microstructures and magnetic properties of ring-shaped Fe-Si alloys produced using concentric and cross-hatch tool paths on a laser-directed energy deposition additive manufacturing system. Concentric-built samples exhibit elongated grain structures while cross-hatch-built samples comprise lower aspect ratio grain structures. Thermal finite element analysis simulations model the stress conditions produced by the different scan path geometries. Microhardness measurements probe the mechanical properties as a function of anneal temperature, providing a qualitative understanding of the intergranular defect density. Soft magnetic properties measured under quasistatic and AC conditions show frequency- and microstructure-dependent coercivity and permeability. Finally, analysis of the core loss quantifies how the build strategies and thermal treatments influence efficiency in electrical power conversion applications. Understanding the influences of scan path geometry and thermal treatment provides a pathway towards application of additively manufactured soft magnetic materials.

Adamczyk, Jesse M.↗
DOE OSTI2018

Stochastic nature of magnetic processes studied by full-field soft X-ray microscopy

In nanomagnetism, one of the crucial scientific questions is whether magnetic behaviors are deterministic or stochastic on a nanoscale. Apart from the exciting physical issue, this question is also of paramount highest relevance for using magnetic materials in a wealth of technological applications such as magnetic storage and sensor devices. In the past, the research on the stochasticity of a magnetic process has been mainly done by macroscopic measurements, which only offer ensemble-averaged information. To give more accurate answer for the question and to fully understand related underlying physics, the direct observation of statistical behaviors in magnetic structures and magnetic phenomena utilizing advanced characterization techniques is highly required. One of the ideal tools for such study is a full-field soft X-ray microscope since it enables imaging of magnetic structures on the large field of view within a few seconds. Here in this paper, we review the stochastic behaviors of various magnetic processes including magnetization reversal process in thin films, magnetic domain wall motions in nanowires, and magnetic vortex formations in nanodisks studied by full-field soft X-ray microscopy. The origin triggering the stochastic nature witnessed in each magnetic process and the way to control the intrinsic nature are also discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Reconfigurable nanoscale soft materials

In this paper, we discuss recent research efforts towards understanding and implementing the physical rules needed to make materials-especially materials composed of nanoscale building blocks-that exhibit the defining characteristics of living systems: adaptive and evolving functional behavior. In particular, we highlight advancements in direct imaging and quantifying of kinetic pathways governing structural reconfiguration in model systems of colloidal nanoparticles as well as emerging opportunities brought by frontier efforts in synthesizing shape-shifting colloids and flexible electronics. Direct observation of kinetic "crossroads" in nanoparticle self-assembly and reconfiguration will offer insight into how these steps can be manipulated to design dynamic, potentially novel materials and devices. Moreover, these principles will not be limited to nanoparticles; when extended to building blocks like soft micelles and proteins, they have the potential to have a similar impact throughout the broader field of soft matter physics.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Combined soft and hard X-ray ambient pressure photoelectron spectroscopy studies of semiconductor/electrolyte interfaces

The development of solar fuel generating materials would greatly benefit from a molecular level understanding of the semiconductor/electrolyte interface and changes in the interface induced by an applied potential and illumination by solar light. Ambient pressure photoelectron spectroscopy techniques with both soft and hard X-rays, AP-XPS and AP-HAXPES respectively, have the potential to markedly contribute to this understanding. In this paper we initially provide two examples of current challenges in solar fuels material development that AP-XPS and AP-HAXPES can directly a ddress. This will be followed by a brief description of the distinguishing and complementary characteristics of soft and hard X-ray AP-XPS and AP-HAXPES and best approaches to achieving monolayer sensitivity in solid/aqueous electrolyte studies. In particular we focus on the detection of surface adsorbed hydroxyl groups in the presence of aqueous hydroxide anions in the electrolyte, a common situation when investigating photoanodes for solar fuel generating applications. Finally, the article concludes by providing an example of a combined AP-XPS and AP-HAXPES study of a semiconductor/aqueous electrolyte interface currently used in water splitting devices specifically the BiVO 4 /aqueous potassium phosphate electrolyte interface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2010

Measuring Interfractional and Intrafractional Motion With Cone Beam Computed Tomography and an Optical Localization System for Lower Extremity Soft Tissue Sarcoma Patients Treated With Preoperative Intensity-Modulated Radiation Therapy

Purpose: To evaluate inter- and intrafractional motion and rotational error for lower extremity soft tissue sarcoma patients by using cone beam computed tomography (CBCT) and an optical localization system. Methods and Materials: Thirty-one immobilized patients received CBCT image-guided intensity-modulated radiation therapy. Setup deviations of >3 mm from the planned isocenter were corrected. A second CBCT acquired before treatment delivery was registered to the planning CT to estimate interfractional setup error retrospectively. Interfractional error and rotational error were calculated in the left-right (LR), superoinferior (SI), and anteroposterior (AP) dimensions. Intrafractional motion was assessed by calculating the maximum relative displacement of optical localization system reflective markers placed on the patient's surface, combined with pre- and postfraction CBCT performed for 17 of the 31 patients once per week. The overall systematic error (SE) and random error (RE) were calculated for the interfractional and intrafractional motion for planning target volume margin calculation. Results: The standard deviation (SD) of the interfractional RE was 1.9 mm LR, 2.1 mm SI, and 1.8 mm AP, and the SE SD was 0.6 mm, 1.2 mm, and 0.7 mm in each dimension, respectively. The overall rotation (inter- and intrafractional) had an RE SD of 0.8{sup o} LR, 1.7{sup o} SI, and 0.7{sup o} AP and an SE SD of 1.1{sup o} LR, 1.3{sup o} SI, and 0.3{sup o} AP. The SD of the overall intrafractional RE was 1.6 mm LR, 1.6 mm SI, and 1.4 mm AP, and the SE SD was 0.7 mm AP, 0.6 mm SI, and 0.6 mm AP. Conclusions: A uniform 5-mm planning target volume margin was quantified for lower extremity soft tissue sarcoma patients and has been implemented clinically for image-guided intensity-modulated radiation therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Low-Dose Neoadjuvant External Beam Radiation Therapy for Soft Tissue Sarcoma

Purpose: For soft tissue sarcoma, neoadjuvant external beam radiation therapy (EBRT) to 50 Gy has the same local control (LC) and overall survival as postoperative radiation therapy (PORT) to 60 Gy, but with increased wound complications. We examined whether low-dose neoadjuvant EBRT would decrease acute toxicity while maintaining LC. Methods and Materials: From 1971 to 2008, 1,765 patients with nonmetastatic soft tissue sarcoma were treated with radiation therapy at Massachusetts General Hospital. We identified 42 patients treated with low-dose neoadjuvant EBRT (median, 20 Gy; range, 16-26) followed by surgical resection and PORT. PORT included EBRT (25 patients; median, 40 Gy; range, 20-56.2), brachytherapy (13 patients; median, 42 Gy; range, 26-50), and intraoperative radiation therapy (IORT) (4 patients; median, 12.5 Gy; range, 8-20). The median total dose was 63.3 Gy (range, 28-78.4). Results: Median follow-up was 36 months (range, 4-318). Severe acute wound complications were reported in 15 patients (36%) and correlated to PORT technique (16% EBRT, 69% brachytherapy, 50% IORT, p = 0.004). The 5-year LC was 73% and correlated to PORT technique (68% EBRT, 100% brachytherapy, 50% IORT, p = 0.03) and histology (p = 0.05), with a trend to improvement if >60 Gy (p = 0.10). The 5-year overall survival was 65% and correlated to extent of resection (p < 0.001) and margin status (p < 0.001). Conclusions: Despite using low-dose neoadjuvant EBRT, we report a high rate of severe acute wound complications that was strongly associated with brachytherapy. Modification of the brachytherapy technique may decrease acute toxicity while maintaining excellent local control. Further study must be conducted before recommending broader application.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Adjuvant Radiotherapy for Pediatric and Young Adult Nonrhabdomyosarcoma Soft-Tissue Sarcoma

Purpose: To evaluate the prognostic factors, outcomes, and complications in patients aged {<=}30 years with resectable nonrhabdomyosarcoma soft-tissue sarcoma treated at the University of Florida with radiotherapy (RT) during a 34-year period. Methods and Materials: A total of 95 pediatric or young adult patients with nonrhabdomyosarcoma soft-tissue sarcoma were treated with curative intent with surgery and RT at the University of Florida between 1973 and 2007. The most common histologic tumor subtypes were synovial sarcoma in 22 patients, malignant fibrous histiocytoma in 19, and malignant peripheral nerve sheath tumor in 11 patients. The mean age at RT was 22 years (range, 6-30). Of the 95 patients, 73 had high-grade tumors; 45 had undergone preoperative RT and 50 postoperative RT. The prognostic factors for survival, local recurrence, and distant recurrence were analyzed. Results: The median follow-up was 7.2 years (range, 0.4-30.5). The actuarial 5-year local control rate was 88%. A microscopically negative margin was associated with superior local control. Although 83% of local recurrence cases initially developed in the absence of metastases, all patients with local failure ultimately died of their disease. The actuarial estimate of 5-year overall survival and disease-free survival was 65% and 63%, respectively. Of all the deaths, 92% were disease related. An early American Joint Committee on Cancer stage, tumor <8 cm, and the absence of neurovascular invasion were associated with superior disease-free survival. The National Cancer Institute Common Toxicity Criteria, version 3, Grade 3-4 treatment complication rate was 9%. No secondary malignancies were observed. Conclusion: In the present large single-institution study, we found positive margins and locally advanced features to be poor prognostic factors for both local progression and survival. The results from the present study have helped to characterize the therapeutic ratio of RT in pediatric and young adult sarcoma patients and have provided a basis for identifying high-risk patients for whom treatment intensification might be justified.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Carbon Ion Radiation Therapy Improves the Prognosis of Unresectable Adult Bone and Soft-Tissue Sarcoma of the Head and Neck

Purpose: To evaluate the safety and efficacy of carbon ion radiotherapy (C-ion RT) with 70.4 GyE for unresectable bone and soft-tissue sarcoma of the adult head and neck. Methods and Materials: Twenty-seven patients (mean age, 46.2 years) were enrolled in this prospective study on C-ion RT with 70.4 GyE/16 fractions (fr) between April 2001 and February 2008. The primary end points were acute and late reactions of normal tissues, local control rate, and overall survival rate. The secondary end point was efficacy of the treatment in comparison to historical results with 57.6 or 64.0 GyE/16 fr. Results: The 3-year local control rate and overall survival rate for all patients were 91.8% (95% confidence interval [CI] = 81.0-100%) and 74.1% (95% CI = 57.5-90.6%), respectively. Acute reaction of Grade 3 or more was observed in only 1 patient. With regard to late reactions, visual loss was observed in 1 patient and a Grade 3 reaction of the maxillary bone was observed in 4 patients. A comparison with historical results revealed that the local control rate with 70.4 GyE was significantly higher than that with 57.6 or 64.0 GyE (3-year, 91.8% vs. 23.6%, p < 0.0001). Furthermore, the overall survival with 70.4 GyE tended to be higher than that with 57.6 or 64.0 GyE (3-year, 74.1% vs. 42.9%, p = 0.09). Conclusion: C-ion RT with 70.4 GyE/16 fr for bone and soft-tissue sarcoma of the adult head and neck appears to be effective with acceptable toxicities in comparison to conventional RT and C-ion RT with lower doses.

62 RADIOLOGY AND NUCLEAR MEDICINE↗