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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 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Challenges in the implementation of dense wavelength division multiplexed (DWDM) optical interconnects using resonant silicon photonics (invited)

In this study, small silicon photonics micro-resonator modulators and filters hold the promise for multi-terabit per-second interconnects at energy consumptions well below 1 pJ/bit. To date, no products exist and little known commercial development is occurring using this technology. Why? In this talk, we review the many challenges that remain to be overcome in bringing this technology from the research labs to the field where they can overcome important commercial, industrial, and national security limitations of existing photonic technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Fielding the LANL Gas Cherenkov Detector (GCD-3) at the National Ignition Facility: The engineering challenges of designing, analyzing, fabricating, testing, and commissioning the next-generation GCD detector and WellDIM3.9m insertion manipulator for use at NIF

We report that fielding the LANL third-generation Gas Cherenkov Detector (GCD-3) at the National Ignition Facility (NIF) revealed an array of complex engineering challenges. Fielding the GCD-3 Detector in a 3.9 meter re-entrant Well on the NIF Target Chamber required the development of a specialized detector deployment system named the WellDIM3.9m Diagnostic Manipulator (WellDIM). The most stringent design requirement entailed a no-load/no-contact condition with the Well, which dictated that all seismic loads be transferred to the Target Chamber port flange. The WellDIM transports the GCD-3 into the Well at a distance of 3.9m from Target Chamber Center. Finally, the GCD-3 Detector, outfitted with additional shielding to mitigate higher NIF backgrounds, will serve as a prototype for the future, heavily shielded “Super-GCD”.

42 ENGINEERING↗
DOE OSTI2019

Fixed-Angle Reflectance from Uranium Compounds and U-Bearing Minerals: Experimental Challenges to Determine the Optical Constants n and k

Fixed-angle reflectance spectroscopy using a commercial Fourier transform infrared (FTIR) spectrometer was employed to derive the optical constants n and k of several uranium compounds. This technique relies upon measurement of the quantitative reflectance R(?) spectra from a polished surface across a broad spectral range (in this case, the mid- and far-IR covering ca. 7500 to 50 cm-1) followed by application of the Kramers-Kronig transformation (KKT). Near-normal fixed-angle measurements as used in this technique require continuous reflectance spectra to as low a wavenumber value as possible. Here, we discuss some of the many challenges in measuring the far-IR and very far-IR (terahertz) spectra using an interferometric instrument, particularly those stemming from small sample sizes, typically just millimeters on a face for crystalline samples, as well as limitations due to optical components and diffraction. We apply this method to single-crystal UO2 and its mineralogical form uraninite, as well as other U-bearing minerals such as autunite [Ca(UO2)2(PO4)2·8-12H2O] and the dehydrated form of autunite, meta-autunite. In addition to the specular reflectance spectra, x-ray diffractometry was used as a confirmatory technique to analyze the surface composition of the species. Deriving the infrared optical constants for such U-bearing species (as well as other solids) will enable nondestructive detection under a variety of environmental and compositional conditions.

Uranium Minerals, infrared spectroscopy, optical c↗
DOE OSTI2014

SU-E-E-03: Developing Solutions to Critical Radiation Oncology Challenges in Tanzania

Purpose: Develop solutions to critical medical physics challenges in Tanzania. Methods: In September of 2013 we began working with Jumaa Bin Dachi, a Therapy Physicist at the Ocean Road Cancer Institute in Dar es Salaam, Tanzania. We developed a bi-lateral learning partnership over the course of eight qualitative Skype meetings with Jumaa. From these meetings we have ascertained that there is a gap between the installation of new equipment and treating patients. This gap has often been overlooked by international partners attempting to improve radiation therapy access. Relationships with academic institutions abroad can fill these gaps, and lead to sustained care of patients needing radiation. Results: Our efforts are best given in a supporting role to help develop solutions and new technology that can reduce the burden on the Medical Physicist. Solutions may include: training material, support for radiation therapy classes, development of appropriate local protocols, and peer-review on documents being produced. New technology needs to focus around simple and easy field shaping, improved patient imaging systems, and systems for patient set-up. We believe our work can help alleviate some of the burdens faced by this institute. Conclusion: While we are just in the beginning stage of this partnership, we believe there is great potential for success between both parties. We hope that the Ocean Road Cancer Institute will benefit from potential funding and resources by partnering with a High Income Country to develop affordable solutions to clinical problems in Tanzania.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-T-244: Motion Control Challenges in High Dose Rate Brachytherapy

Purpose: High dose rate (HDR) brachytherapy dose distribution is highly localized and has a very sharp fall-off. Thus the one of the most important part of the treatment is the localization and immobilization of the applicator from the implantation to the setup verification to the treatment delivery. The smallest motions of the patient can induce a small rotation, tilt, or translational movement of the applicator that can convert into miss of a significant part of the tumor or to over irradiating a nearby critical organ.The purpose of this study is to revise most of the HDR types of treatments with their applicators and their localization challenges. Since every millimeter of misplacement counts the study will look into the necessity of increasing the immobilization for several types of applicators. Methods: The study took over 136 plans generated by the treatment planning system (TPS) looking into the applicator placement in regard to the organs at risk (OR) and simulated the three possible displacements at the hottest dose point on the critical organ for several accessories to evaluate the variation of the delivered dose at the point due to the displacement. Results: Many of the present immobilization devices produced for external radiotherapy can be used to improve the localization of HDR applicators during transportation of the patient and during treatment. Conclusion: This study data indicates that an improvement of the immobilization devices for HDR is absolutely necessary. Better applicator fixation devices are required too. Developing new immobilization devices for all the applicators is recommended.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-T-591: Measurement and Monte Carlo Simulation of Stray Neutrons in Passive Scattering Proton Therapy: Needs and Challenges

Purpose: Measure stray radiation inside a passive scattering proton therapy facility, compare values to Monte Carlo (MC) simulations and identify the actual needs and challenges. Methods: Measurements and MC simulations were considered to acknowledge neutron exposure associated with 75 MeV ocular or 180 MeV intracranial passively scattered proton treatments. First, using a specifically-designed high sensitivity Bonner Sphere system, neutron spectra were measured at different positions inside the treatment rooms. Next, measurement-based mapping of neutron ambient dose equivalent was fulfilled using several TEPCs and rem-meters. Finally, photon and neutron organ doses were measured using TLDs, RPLs and PADCs set inside anthropomorphic phantoms (Rando, 1 and 5-years-old CIRS). All measurements were also simulated with MCNPX to investigate the efficiency of MC models in predicting stray neutrons considering different nuclear cross sections and models. Results: Knowledge of the neutron fluence and energy distribution inside a proton therapy room is critical for stray radiation dosimetry. However, as spectrometry unfolding is initiated using a MC guess spectrum and suffers from algorithmic limits a 20% spectrometry uncertainty is expected. H*(10) mapping with TEPCs and rem-meters showed a good agreement between the detectors. Differences within measurement uncertainty (10–15%) were observed and are inherent to the energy, fluence and directional response of each detector. For a typical ocular and intracranial treatment respectively, neutron doses outside the clinical target volume of 0.4 and 11 mGy were measured inside the Rando phantom. Photon doses were 2–10 times lower depending on organs position. High uncertainties (40%) are inherent to TLDs and PADCs measurements due to the need for neutron spectra at detector position. Finally, stray neutrons prediction with MC simulations proved to be extremely dependent on proton beam energy and the used nuclear models and cross sections. Conclusion: This work highlights measurement and simulation limits for ion therapy radiation protection applications.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2015

MO-AB-201-02: The RSO and The RSC: Challenges and Opportunities

The role of the Radiation Safety Officer at a medical facility can be complicated. The complexity of the position is based on the breadth of services provided at the institution and the nature of the radioactive materials license. Medical practices are constantly changing and the use of ionizing radiation continues to rise in this area. Some of the newer medical applications involving radiation have unique regulatory and safety issues that must be addressed. Oversight of the uses of radiation start at the local level (radiation safety officer, radiation safety committee) and are heavily impacted by outside agencies (i.e. Nuclear Regulatory Commission, State Radiologic Health, The Joint Commission (TJC), etc). This session will provide both an overview of regulatory oversight and essential compliance practices as well as practical ways to assess and introduce some of the new applications utilizing radioactive materials into your medical facility. Learning Objectives: Regulatory Compliance and Safety with New Radiotherapies: Spheres and Ra-223 (Lance Phillips) Understand the radioactive materials license amendment process to add new radiotherapies (i.e., SIR-Spheres, Therasphere, Xofigo). Understand the AU approval process for microspheres and Xofigo. Examine the training and handling requirements for new procedures. Understand the process involved with protocol development, SOP in order to define roles and responsibilities. The RSO and The RSC: Challenges and Opportunities (Colin Dimock) Understand how to form an effective Committee. Examine what the Committee does for the Program and the RSO. Understand the importance of Committee engagement. Discuss the balance of the complimentary roles of the RSO and the Committee. The Alphabet Soup of Regulatory Compliance: Being Prepared for Inspections (Linda Kroger) Recognize the various regulatory bodies and organizations with oversight or impact in Nuclear Medicine, Radiology and Radiation Oncology. Examine 10CFR35 requirements as they relate to the everyday practice of Nuclear Medicine and Radiation Oncology. Understand the nature of available guidance documents (e.g., NUREG 1556). Examine the commonalities between TJC and CMS preparedness.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

TU-CD-BRD-01: Making Incident Learning Practical and Useful: Challenges and Previous Experiences

It has long been standard practice in radiation oncology to report internally when a patient’s treatment has not gone as planned and to report events to regulatory agencies when legally required. Most potential errors are caught early and never affect the patient. Quality assurance steps routinely prevent errors from reaching the patient, and these “near misses” are much more frequent than treatment errors. A growing number of radiation oncology facilities have implemented incident learning systems to report and analyze both errors and near misses. Using the term “incident learning” instead of “event reporting” emphasizes the need to use these experiences to change the practice and make future errors less likely and promote an educational, non-punitive environment. There are challenges in making such a system practical and effective. Speakers from institutions of different sizes and practice environments will share their experiences on how to make such a system work and what benefits their clinics have accrued. Questions that will be addressed include: How to create a system that is easy for front line staff to access How to motivate staff to report How to promote the system as positive and educational and not punitive or demeaning How to organize the team for reviewing and responding to reports How to prioritize which reports to discuss in depth How not to dismiss the rest How to identify underlying causes How to design corrective actions and implement change How to develop useful statistics and analysis tools How to coordinate a departmental system with a larger risk management system How to do this without a dedicated quality manager Some speakers’ experience is with in-house systems and some will share experience with the AAPM/ASTRO national Radiation Oncology Incident Learning System (RO-ILS). Reports intended to be of value nationally need to be comprehensible to outsiders; examples of useful reports will be shown. There will be ample time set aside for audience members to contribute to the discussion. Learning Objectives: Learn how to promote the use of an incident learning system in a clinic. Learn how to convert “event reporting” into “incident learning”. See examples of practice changes that have come out of learning systems. Learn how the RO-ILS system can be used as a primary internal learning system. Learn how to create succinct, meaningful reports useful to outside readers. Gary Ezzell chairs the AAPM committee overseeing RO-ILS and has received an honorarium from ASTRO for working on the committee reviewing RO-ILS reports. Derek Brown is a director of http://TreatSafely.org . Brett Miller has previously received travel expenses and an honorarium from Varian. Phillip Beron has nothing to report.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Vision 20/20: Magnetic resonance imaging-guided attenuation correction in PET/MRI: Challenges, solutions, and opportunities

Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing novel strategies for deriving accurate attenuation maps with the aim to improve the quantitative accuracy of these emerging hybrid imaging systems. The attenuation map in PET/MRI should ideally be derived from anatomical MR images; however, MRI intensities reflect proton density and relaxation time properties of biological tissues rather than their electron density and photon attenuation properties. Therefore, in contrast to PET/computed tomography, there is a lack of standardized global mapping between the intensities of MRI signal and linear attenuation coefficients at 511 keV. Moreover, in standard MRI sequences, bones and lung tissues do not produce measurable signals owing to their low proton density and short transverse relaxation times. MR images are also inevitably subject to artifacts that degrade their quality, thus compromising their applicability for the task of attenuation correction in PET/MRI. MRI-guided attenuation correction strategies can be classified in three broad categories: (i) segmentation-based approaches, (ii) atlas-registration and machine learning methods, and (iii) emission/transmission-based approaches. This paper summarizes past and current state-of-the-art developments and latest advances in PET/MRI attenuation correction. The advantages and drawbacks of each approach for addressing the challenges of MR-based attenuation correction are comprehensively described. The opportunities brought by both MRI and PET imaging modalities for deriving accurate attenuation maps and improving PET quantification will be elaborated. Future prospects and potential clinical applications of these techniques and their integration in commercial systems will also be discussed.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2016

SU-F-T-139: Meeting the Challenges of Quality Control in the TOPAS Monte Carlo Simulation Toolkit for Proton Therapy

Purpose: Monte Carlo particle transport simulation (MC) codes have become important tools in proton therapy and biology, both for research and practice. TOPAS is an MC toolkit serving users worldwide (213 licensed users at 95 institutions in 21 countries). It provides unprecedented ease in 4D placement of geometry components, beam sources and scoring through its user-friendly and reproducible parameter file interface. Quality control (QC) of stochastic simulation software is inherently difficult, and the versatility of TOPAS introduces additional challenges. But QC is vital as the TOPAS development team implements new features, addresses user feedback and reacts to upgrades of underlying software (i.e. Geant4). Methods: Whenever code is committed to our repository, over 50 separate module tests are automatically triggered via a continuous integration service. They check that the various module options execute successfully and that their results are statistically consistent with previous reference values. Prior to each software release, longer end-to-end tests automatically validate TOPAS against experimental data and a TOPAS benchmark. These include simulating multiple properties of spread-out Bragg peaks, validating nuclear models, and searching for differences in patient simulations. Results: Continuous integration has proven effective in catching regressions at the time they are introduced, particularly when implementing new features that involve refactoring code (e.g. multithreading and ntuple output). Code coverage statistics highlight untested portions of code and guide development of new tests. The various end-to-end tests demonstrate that TOPAS accurately describes the physics of proton therapy within clinical tolerances. Conclusion: The TOPAS QC strategy of frequent short tests and pre-release long tests has led to a more reliable tool. However, the versatility of TOPAS makes it difficult to predict how users might combine different modules, and so QC ultimately remains a partnership between the developer and the user. This work was funded by National Cancer Institute grant R01 CA 140735.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

WE-H-BRB-03: Learning Health Systems for Radiation Oncology: Needs and Challenges for Future Success

Big Data in Radiation Oncology: (1) Overview of the NIH 2015 Big Data Workshop, (2) Where do we stand in the applications of big data in radiation oncology?, and (3) Learning Health Systems for Radiation Oncology: Needs and Challenges for Future Success The overriding goal of this trio panel of presentations is to improve awareness of the wide ranging opportunities for big data impact on patient quality care and enhancing potential for research and collaboration opportunities with NIH and a host of new big data initiatives. This presentation will also summarize the Big Data workshop that was held at the NIH Campus on August 13–14, 2015 and sponsored by AAPM, ASTRO, and NIH. The workshop included discussion of current Big Data cancer registry initiatives, safety and incident reporting systems, and other strategies that will have the greatest impact on radiation oncology research, quality assurance, safety, and outcomes analysis. Learning Objectives: To discuss current and future sources of big data for use in radiation oncology research To optimize our current data collection by adopting new strategies from outside radiation oncology To determine what new knowledge big data can provide for clinical decision support for personalized medicine L. Xing, NIH/NCI Google Inc.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Deletion of the H108R Gene Reduces Virulence of the Pandemic Eurasia Strain of African Swine Fever Virus with Surviving Animals Being Protected against Virulent Challenge

African swine fever virus (ASFV) is the etiological agent of African swine fever (ASF), a devastating disease affecting domestic and wild swine and currently causing a global pandemic, severely affecting swine production. Here, we demonstrate that the deletion of the previously uncharacterized ASFV gene, H108R from the highly virulent ASFV-Georgia2007 (ASFV-G) genome strain, reduces virulence in domestic swine. ASFV-G-DH108R, a recombinant virus with the H108R gene deleted, was used to evaluate the involvement of the H108R gene for ASFV replication and virulence in swine. ASFV-G-DH108R showed a delayed replication in swine macrophage cultures. A group of five pigs, intramuscularly inoculated with 102 HAD50 of ASFV-G-DH108R, was observed over a 28-day period and compared with a similar group of animals inoculated with similar doses of the parental virulent virus. While all animals inoculated with ASFV-G developed an acute fatal disease, ASFV-G-DH108R inoculated animals, with the exception of one animal showing a protracted but fatal form of the disease, all survived the infection, remaining clinically healthy during the observational period. The surviving animals presented protracted viremias with lower virus titers compared with those of animals inoculated with the parental virus, and all of them developed a strong virus-specific antibody response. Importantly, all animals surviving ASFV-G-DAH108R infection were protected when challenged with the virulent parental strain, ASFV-G. This report constitutes the first evidence that the H108R gene is involved in ASFV virulence in swine and that the deletion of this gene may be used as a tool to increase the attenuation of currently experimental vaccines to improve their safety profiles.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Deletion of E184L, a Putative DIVA Target from the Pandemic Strain of African Swine Fever Virus, Produces a Reduction in Virulence and Protection against Virulent Challenge

African swine fever (ASF) is currently causing a major pandemic affecting the swine industry and protein availability from Central Europe to East and South Asia. No commercial vaccines are available, making disease control dependent on the elimination of affected animals. Here, we show that the deletion of the African swine fever virus (ASFV) E184L gene from the highly virulent ASFV Georgia 2010 (ASFV-G) isolate produces a reduction in virus virulence during the infection in swine. Of domestic pigs intramuscularly inoculated with a recombinant virus lacking the E184L gene (ASFV-GDE184L), 40% experienced a significantly (5 days) delayed presentation of clinical disease and, overall, had a 60% rate of survival compared to animals inoculated with the virulent parental ASFV-G. Importantly, all animals surviving ASFV-G-DE184L infection developed a strong antibody response and were protected when challenged with ASFV-G. As expected, a pool of sera from ASFV-G-DE184L-inoculated animals lacked any detectable antibody response to peptides partially representing the E184L protein, while sera from animals inoculated with an efficacious vaccine candidate, ASFV-GDMGF, strongly recognize the same set of peptides. These results support the potential use of the E184L deletion for the development of vaccines able to differentiate infected from vaccinated animals (DIVA). Therefore, it is shown here that the E184L gene is a novel ASFV determinant of virulence that can potentially be used to increase safety in preexisting vaccine candidates, as well as to provide them with DIVA capabilities. To our knowledge, E184L is the first ASFV gene product experimentally shown to be a functional DIVA antigenic marker.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Priorities, opportunities, and challenges for integrating microorganisms into Earth system models for climate change prediction

ABSTRACT Climate change jeopardizes human health, global biodiversity, and sustainability of the biosphere. To make reliable predictions about climate change, scientists use Earth system models (ESMs) that integrate physical, chemical, and biological processes occurring on land, the oceans, and the atmosphere. Although critical for catalyzing coupled biogeochemical processes, microorganisms have traditionally been left out of ESMs. Here, we generate a “top 10” list of priorities, opportunities, and challenges for the explicit integration of microorganisms into ESMs. We discuss the need for coarse-graining microbial information into functionally relevant categories, as well as the capacity for microorganisms to rapidly evolve in response to climate-change drivers. Microbiologists are uniquely positioned to collect novel and valuable information necessary for next-generation ESMs, but this requires data harmonization and transdisciplinary collaboration to effectively guide adaptation strategies and mitigation policy.

Microbiology↗
DOE OSTI2020

QCD challenges from pp to A–A collisions

This paper is a write-up of the ideas that were presented, developed and discussed at the third International Workshop on QCD Challenges from pp to A–A, which took place in August 2019 in Lund, Sweden. The goal of the workshop was to focus on some of the open questions in the field and try to come up with concrete suggestions for how to make progress on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Solving challenges in QCD 3D partonic distributions

The superior luminosity and high polarization of CEBAF, combined with the high resolution and excellent particle identification capabilities of its detectors, as well as the ability for multidimensional and multiparticle detection using polarized targets, make Jefferson Lab uniquely positioned to disentangle the genuine intrinsic transverse structure of hadrons encoded in 3D partonic distributions—particularly in the kinematic regime dominated by valence quarks. The inclusion of Jefferson Lab data on semi-inclusive and hard exclusive hadron production has the potential to dramatically advance our understanding of non-perturbative QCD dynamics. Although a wealth of data from various Jefferson Lab experiments is already available, its incorporation into phenomenological studies has been slow, and a significant portion of data from other leptoproduction experiments is still missing from global fits. In this contribution, we discuss the existing challenges and outline a path forward for improving the analysis of low center-of-mass electroproduction experiments in general, and Jefferson Lab data in particular.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

QCD challenges from pp to AA collisions: 4th edition

Abstract This paper is a write-up of the ideas that were presented, developed and discussed at the fourth International Workshop on QCD Challenges from pp to AA, which took place in February 2023 in Padua, Italy. The goal of the workshop was to focus on some of the open questions in the field of high-energy heavy-ion physics and to stimulate the formulation of concrete suggestions for making progresses on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results.

Physics↗
DOE OSTI2021

Challenges and opportunities in verification and validation of low temperature plasma simulations and experiments

This paper describes the verification and validation (V&V) framework developed for the stochastic Particle-in-Cell, Direct Simulation Monte Carlo code Aleph. An ideal framework for V&V from the viewpoint of the authors is described where a physics problem is defined, and relevant physics models and parameters to the defined problem are assessed and captured in a Phenomena Identification and Ranking Table (PIRT). Furthermore, numerous V&V examples guided by the PIRT for a simple gas discharge are shown to demonstrate the V&V process applied to a real-world simulation tool with the overall goal to demonstrably increase the confidence in the results for the simulation tool and its predictive capability. Although many examples are provided here to demonstrate elements of the framework, the primary goal of this work is to introduce this framework and not to provide a fully complete implementation, which would be a much longer document. Comparisons and contrasts are made to more usual approaches to V&V, and techniques new to the low-temperature plasma community are introduced. Specific challenges relating to the sufficiency of available data (e.g., cross sections), the limits of ad hoc validation approaches, the additional difficulty of utilizing a stochastic simulation tool, and the extreme cost of formal validation are discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗