Insightful heat exchanger network retrofit design using Monte Carlo simulation
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Lal, Nathan S.↗
SEARCH · Engineering Papers
Results for “Neal”
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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Integrated analysis of increased bioenergy futures in India
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Graham, Neal T. (ORCID:0000000168675475)↗
Thirdhand tobacco smoke exposure increases the genetic background-dependent risk of pan-tumor development in Collaborative Cross mice
Increasing evidence has shown that thirdhand smoke (THS) exposure is likely to induce adverse health effects. An important knowledge gap remains in our understanding of THS exposure related to cancer risk in the human population. Population-based animal models are useful and powerful in investigating the interplay between host genetics and THS exposure on cancer risk. Here, we used the Collaborative Cross (CC) mouse population-based model system, which recapitulates the genetic and phenotypic diversity observed in the human population, to assess cancer risk after a short period of exposure, between 4 and 9 weeks of age. Eight CC strains (CC001, CC019, CC026, CC036, CC037, CC041, CC042 and CC051) were included in our study. We quantified pan-tumor incidence, tumor burden per mouse, organ tumor spectrum and tumor-free survival until 18 months of age. At the population level, we observed a significantly increased pan-tumor incidence and tumor burden per mouse in THS-treated mice as compared to the control (p = 3.04E-06). Lung and liver tissues exhibited the largest risk of undergoing tumorigenesis after THS exposure. Tumor-free survival was significantly reduced in THS-treated mice compared to control (p = 0.044). At the individual strain level, we observed a large variation in tumor incidence across the 8 CC strains. CC036 and CC041 exhibited a significant increase in pan-tumor incidence (p = 0.0084 and p = 0.000066, respectively) after THS exposure compared to control. We conclude that early-life THS exposure increases tumor development in CC mice and that host genetic background plays an important role in individual susceptibility to THS-induced tumorigenesis. Genetic background is an important factor that should be taken into account when determining human cancer risk of THS exposure.
60 APPLIED LIFE SCIENCES↗
The estimated change in the level and distribution of PM2.5-attributable health impacts in the United States: 2005–2014
Highlights: • PM{sub 2.5} exposure and risk fell significantly between 2005 and 2014. • The fraction of deaths due to PM{sub 2.5} falls from 6.1% to 4.6%. • PM{sub 2.5} risk is becoming more equitably distributed, including those most susceptible. Photochemical modeling can predict the level and distribution of pollutant concentrations over time, but is resource-intensive. Partly for this reason, there are few studies exploring the multi-year trajectory of the historical change in fine particle (PM{sub 2.5}) levels and associated health impacts in the U.S.
54 ENVIRONMENTAL SCIENCES↗
Geothermal production and reduced seismicity: Correlation and proposed mechanism
Not Available
15 GEOTHERMAL ENERGY↗
Assessment of BISON capabilities for component-level prediction of tritium transport in fusion and fission applications
Here we assessed the hydrogen migration and redistribution model implemented in the BISON fuel performance code for component-level tritium transport applications in fusion and fission example scenarios. We developed BISON models of an ITER heat exchanger, light water reactor fuel cladding, and a fluoride salt cooled high temperature reactor heat exchanger. Reasonable agreement between reported values in reference studies and BISON predictions demonstrated the ability of the BISON models to predict tritium transport behavior through steel materials. Next, sensitivity and uncertainty analysis was used to understand key parameter sensitivities within the BISON model for evaluation of tritium migration and redistribution. . The sensitivity analysis showed that the diffusivity activation energy was the most important parameter and that the heat of transport was the least important parameter for tritium migration in steels. Overall, the capabilities of the BISON code for component level modeling of tritium transport are promising.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
CG-Kit: Code Generation Toolkit for performant and maintainable variants of source code applied to Flash-X hydrodynamics simulations
CG-Kit is a new Code Generation tool-Kit that we have developed as a part of the solution for portability and maintainability for multiphysics computing applications. The development of CG-Kit is rooted in the urgent need created by the shifting landscape of high-performance computing platforms and the algorithmic complexities of a particular large-scale multiphysics application: Flash-X. To efficiently use computing resources on a heterogeneous node, an application must have a map of computation to resources and a mechanism to move the data and computation to the resources according to the map. Most existing performance portability solutions are focussed on abstracting the expression of computations so that a unified source code can be specialized to run on different resources. However, such an approach is insufficient for a code like Flash-X, which has a multitude of code components that can be assembled in various permutations and combinations to form different instances of applications. Similar challenges apply to any code that has composability, where a single specified way of apportioning work among devices may not be optimal. Additionally, use cases arise where the optimal control flow of computation may differ for different devices while the underlying numerics remain identical. This combination leads to unique challenges including handling an existing large code base in Fortran and/or C/C++, subdivision of code into a great variety of units supporting a wide range of physics and numerical methods, different parallelization techniques for distributed and shared memory systems and accelerator devices, and heterogeneity of computing platforms requiring coexisting variants of parallel algorithms. All of these challenges demand that scientific software developers apply existing knowledge about domain applications, algorithms, and computing platforms to determine custom abstractions and granularity for code generation. There is a critical lack of tools to tackle those problems. CG-Kit is designed to fill this gap by providing a user with the ability to express their desired control flow and computation-to-resource map in the form a pseudocode-like recipe. It consists of standalone tools that can be combined into highly specific and, we argue, highly effective portability and maintainability toolchains. Here we present the design of our new tools: parametrized source trees, control flow graphs, and recipes. The tools are implemented in Python. They are agnostic to the programming language of the source code targeted for code generation. In conclusion, we demonstrate the capabilities of the toolkit with two examples, first, multithreaded variants of the basic AXPY operation, and second, variants of parallel algorithms within a hydrodynamics solver, called Spark, from Flash-X that operates on block-structured adaptive meshes.
Algorithmic portability↗
ALEGRA: Finite element modeling for shock hydrodynamics and multiphysics
ALEGRA is a multiphysics finite-element shock hydrodynamics code, under development at Sandia National Laboratories since 1990. Fully coupled multiphysics capabilities include transient magnetics, magnetohydrodynamics, electromechanics, and radiation transport. Importantly, ALEGRA is used to study hypervelocity impact, pulsed power devices, and radiation effects. The breadth of physics represented in ALEGRA is outlined here, along with simulated results for a selected hypervelocity impact experiment.
42 ENGINEERING↗
Stereotactic Ablative Radiation Therapy for Centrally Located Early Stage or Isolated Parenchymal Recurrences of Non-Small Cell Lung Cancer: How to Fly in a “No Fly Zone”
Purpose: We extended our previous experience with stereotactic ablative radiation therapy (SABR; 50 Gy in 4 fractions) for centrally located non-small cell lung cancer (NSCLC); explored the use of 70 Gy in 10 fractions for cases in which dose-volume constraints could not be met with the previous regimen; and suggested modified dose-volume constraints. Methods and Materials: Four-dimensional computed tomography (4DCT)-based volumetric image-guided SABR was used for 100 patients with biopsy-proven, central T1-T2N0M0 (n=81) or isolated parenchymal recurrence of NSCLC (n=19). All disease was staged with positron emission tomography/CT; all tumors were within 2 cm of the bronchial tree, trachea, major vessels, esophagus, heart, pericardium, brachial plexus, or vertebral body. Endpoints were toxicity, overall survival (OS), local and regional control, and distant metastasis. Results: At a median follow-up time of 30.6 months, median OS time was 55.6 months, and the 3-year OS rate was 70.5%. Three-year cumulative actuarial local, regional, and distant control rates were 96.5%, 87.9%, and 77.2%, respectively. The most common toxicities were chest-wall pain (18% grade 1, 13% grade 2) and radiation pneumonitis (11% grade 2 and 1% grade 3). No patient experienced grade 4 or 5 toxicity. Among the 82 patients receiving 50 Gy in 4 fractions, multivariate analyses showed mean total lung dose >6 Gy, V{sub 20} >12%, or ipsilateral lung V{sub 30} >15% to independently predict radiation pneumonitis; and 3 of 9 patients with brachial plexus D{sub max} >35 Gy experienced brachial neuropathy versus none of 73 patients with brachial D{sub max} <35 Gy (P=.001). Other toxicities were analyzed and new dose-volume constraints are proposed. Conclusions: SABR for centrally located lesions produces clinical outcomes similar to those for peripheral lesions when normal tissue constraints are respected.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
Outcomes for Spine Stereotactic Body Radiation Therapy and an Analysis of Predictors of Local Recurrence
Purpose: To investigate local control, survival outcomes, and predictors of local relapse for patients treated with spine stereotactic body radiation therapy. Methods and Materials: We reviewed the records of 332 spinal metastases consecutively treated with stereotactic body radiation therapy between 2002 and 2012. The median follow-up for all living patients was 33 months (range, 0-111 months). Endpoints were overall survival and local control (LC); recurrences were classified as either in-field or marginal. Results: The 1-year actuarial LC and overall survival rates were 88% and 64%, respectively. Patients with local relapses had poorer dosimetric coverage of the gross tumor volume (GTV) compared with patients without recurrence (minimum dose [Dmin] biologically equivalent dose [BED] 23.9 vs 35.1 Gy, P<.001; D98 BED 41.8 vs 48.1 Gy, P=.001; D95 BED 47.2 vs 50.5 Gy, P=.004). Furthermore, patients with marginal recurrences had poorer prescription coverage of the GTV (86% vs 93%, P=.01) compared with those with in-field recurrences, potentially because of more upfront spinal canal disease (78% vs 24%, P=.001). Using a Cox regression univariate analysis, patients with a GTV BED Dmin ≥33.4 Gy (median dose) (equivalent to 14 Gy in 1 fraction) had a significantly higher 1-year LC rate (94% vs 80%, P=.001) compared with patients with a lower GTV BED Dmin; this factor was the only significant variable on multivariate Cox analysis associated with LC (P=.001, hazard ratio 0.29, 95% confidence interval 0.14-0.60) and also was the only variable significant in a separate competing risk multivariate model (P=.001, hazard ratio 0.30, 95% confidence interval 0.15-0.62). Conclusions: Stereotactic body radiation therapy offers durable control for spinal metastases, but there is a subset of patients that recur locally. Patients with local relapse had significantly poorer tumor coverage, which was likely attributable to treatment planning directives that prioritized the spinal cord constraints over tumor coverage. When possible, we recommend maintaining a GTV Dmin above 14 Gy in 1 fraction and 21 Gy in 3 fractions.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
Phase 1 Dose Escalation Study of Accelerated Radiation Therapy With Concurrent Chemotherapy for Locally Advanced Lung Cancer
Purpose: To determine the maximum tolerated dose of radiation therapy (RT) given in an accelerated fashion with concurrent chemotherapy using intensity modulated RT. Methods and Materials: Patients with locally advanced lung cancer (non-small cell and small cell) with good performance status and minimal weight loss received concurrent cisplatin and etoposide with RT. Intensity modulated RT with daily image guidance was used to facilitate esophageal avoidance and delivered using 6 fractions per week (twice daily on Fridays with a 6-hour interval). The dose was escalated from 58 Gy to a planned maximum dose of 74 Gy in 4 Gy increments in a standard 3 + 3 trial design. Dose-limiting toxicity (DLT) was defined as acute grade 3-5 nonhematologic toxicity attributed to RT. Results: A total of 24 patients were enrolled, filling all dose cohorts, all completing RT and chemotherapy as prescribed. Dose-limiting toxicity occurred in 1 patient at 58 Gy (grade 3 esophagitis) and 1 patient at 70 Gy (grade 3 esophageal fistula). Both patients with DLTs had large tumors (12 cm and 10 cm, respectively) adjacent to the esophagus. Three additional patients were enrolled at both dose cohorts without further DLT. In the final 74-Gy cohort, no DLTs were observed (0 of 6). Conclusions: Dose escalation and acceleration to 74 Gy with intensity modulated RT and concurrent chemotherapy was tolerable, with a low rate of grade ≥3 acute esophageal reactions.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
Distribution of Cervical Lymph Node Metastases From Squamous Cell Carcinoma of the Oropharynx in the Era of Risk Stratification Using Human Papillomavirus and Smoking Status
Purpose/Objective(s): To investigate the factors contributing to the clinical presentation of oropharyngeal squamous cell carcinoma (OPSCC) in the era of risk stratification using human papilloma virus (HPV) and smoking status. Methods and Materials: All patients with OPSCC presenting to our institutional multidisciplinary clinic from January 2009 to June 2015 were reviewed from a prospective database. The patients were grouped as being at low risk, intermediate risk, and high risk in the manner described by Ang et al. Variance in clinical presentation was examined using χ{sup 2}, Kruskal-Wallis, Mann-Whitney, and logistic regression analyses. Results: The rates of HPV/p16 positivity (P<.001), never-smoking (P=.016), and cervical lymph node metastases (P=.023) were significantly higher for patients with OPSCC of the tonsil, base of tongue (BOT), or vallecula subsites when compared with pharyngeal wall or palate subsites. Low-risk patients with tonsil, base of tongue, or vallecula primary tumors presented with nodal stage N2a at a much higher than expected frequency (P=.007), and high-risk patients presented with tumor stage T4 at a much higher than expected frequency (P=.003). Patients with BOT primary tumors who were never-smokers were less likely to have clinically involved ipsilateral neck disease than were former smokers (odds ratio 1.8; P=.038). The distribution of cervical lymph node metastases was not associated with HPV/p16 positivity, risk group, or subsite. When these data were compared with those in historical series, no significant differences were seen in the patterns of cervical lymph node metastases for patients with OPSCC. Conclusions: For patients with OPSCC differences in HPV status, smoking history and anatomic subsite were associated with differences in clinical presentation but not with distribution of cervical lymph node metastases. Historical series describing the patterns of cervical lymph node metastases in patients with OPSCC remain clinically relevant.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
A Multi-institutional Comparison of SBRT and IMRT for Definitive Reirradiation of Recurrent or Second Primary Head and Neck Cancer
Two modern methods of reirradiation, intensity modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT), are established for patients with recurrent or second primary squamous cell carcinoma of the head and neck (rSCCHN). We performed a retrospective multi-institutional analysis to compare methods.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
Vorinostat and Concurrent Stereotactic Radiosurgery for Non-Small Cell Lung Cancer Brain Metastases: A Phase 1 Dose Escalation Trial
Purpose: To determine the maximum tolerated dose (MTD) of vorinostat, a histone deacetylase inhibitor, given concurrently with stereotactic radiosurgery (SRS) to treat non-small cell lung cancer (NSCLC) brain metastases. Secondary objectives were to determine toxicity, local failure, distant intracranial failure, and overall survival rates. Materials and Methods: In this multicenter study, patients with 1 to 4 NSCLC brain metastases, each ≤2 cm, were enrolled in a phase 1, 3 + 3 dose escalation trial. Vorinostat dose levels were 200, 300, and 400 mg orally once daily for 14 days. Single-fraction SRS was delivered on day 3. A dose-limiting toxicity (DLT) was defined as any Common Terminology Criteria for Adverse Events version 3.0 grade 3 to 5 acute nonhematologic adverse event related to vorinostat or SRS occurring within 30 days. Results: From 2009 to 2014, 17 patients were enrolled and 12 patients completed study treatment. Because no DLTs were observed, the MTD was established as 400 mg. Acute adverse events were reported by 10 patients (59%). Five patients discontinued vorinostat early and withdrew from the study. The most common reasons for withdrawal were dyspnea (n=2), nausea (n=1), and fatigue (n=2). With a median follow-up of 12 months (range, 1-64 months), Kaplan-Meier overall survival was 13 months. There were no local failures. One patient (8%) at the 400-mg dose level with a 2.0-cm metastasis developed histologically confirmed grade 4 radiation necrosis 2 months after SRS. Conclusions: The MTD of vorinostat with concurrent SRS was established as 400 mg. Although no DLTs were observed, 5 patients withdrew before completing the treatment course, a result that emphasizes the need for supportive care during vorinostat administration. There were no local failures. A larger, randomized trial may evaluate both the tolerability and potential local control benefit of vorinostat concurrent with SRS for brain metastases.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
Refining Patient Selection for Reirradiation of Head and Neck Squamous Carcinoma in the IMRT Era: A Multi-institution Cohort Study by the MIRI Collaborative
The therapeutic ratio of reirradiation for recurrent or second primary (RSP) squamous carcinoma of the head and neck may be improved in the intensity modulated radiation therapy (IMRT) era. However, patient selection for reirradiation remains challenging. We performed a multi-institution cohort study to investigate modern outcomes after IMRT-based reirradiation and to identify prognostic subgroups.
62 RADIOLOGY AND NUCLEAR MEDICINE↗
Single-Arm Phase 2 Trial of Elective Nodal Dose Reduction for Patients With Locoregionally Advanced Squamous Cell Carcinoma of the Head and Neck
To evaluate a novel chemoradiation therapy (CRT) regimen for patients with squamous cell carcinoma of the head and neck (SCCHN) incorporating a lower intensity modulated radiation therapy dose to electively treated neck lymph nodes than is currently standard.
62 RADIOLOGY AND NUCLEAR MEDICINE↗