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Ensuring data preservation is a top priority for the Organization for Economic Co-operation and Development (OECD), Nuclear Energy Agency (NEA) Data Bank. Within this context, “preserving data” encompasses activities such as verifying, processing, sharing, improving, and storing the data. The NEA aims to automate these processes to the greatest extent possible, with the goal of providing the JEFF community with reproducible, high-quality data. To achieve this, the Data Bank has chosen to utilize GitLab, a web-based distributed Version Control System that facilitates the collaboration of different users. The author will present the current progress of the NEA pipeline, an ongoing collaborative initiative aimed at standardizing the processing, verification, and validation of nuclear data.

The SCALE transport lattice code, Polaris, has been previously developed to generate few-group homogenized cross sections for whole-core nodal diffusion simulators in which the embedded self-shielding method (ESSM) is used for resonance self-shielding calculations to process cross sections. Although the ESSM capability has been very successful in light-water reactor analysis, it may require enhancements in computational efficiency; treatment of spatially dependent resonance self-shielding effects; and handling of interrelated resonance effects among fuel, cladding, and control rod materials. Therefore, this study focuses on improving computational efficiency by using a Dancoff-based Wigner–Seitz approximation combined with a material-based resonance categorization, through which a spatially dependent ESSM capability is developed to accurately estimate self-shielded cross sections inside the fuel. Benchmark results show that the new capability significantly enhances computational efficiency and accuracy for spatially dependent local zones within the fuel and through depletion.

We derive an effective Reich-Moore approximation (RMA) of the Wigner-Eisenbud R -matrix formalism parameterized by complex-valued resonance energies and widths; this RMA exactly reproduces the total eliminated cross section. We show that resonance parameters evaluated for a conventional boundary conditions (BCs), B c = S c (E),are approximately equal to the R -matrix parameters in Park’s formalism by employing a linear approximation of the shift function therein [T.-S. Park, Phys. Rev. C 106 (2021) 064612]. We outline a method for converting Park’s observed reduced width amplitudes (RWAs) and their covariance matrix into Brune’s alternative R -matrix RWAs and their covariance matrix [C. Brune, Phys. Rev. C 66 (2002) 044611]. We extend the Park’s R -matrix formalism into the complex plane by introducing a complex-valued basis set of eigenfunctions of a complex-symmetric (non-Hermitian) Hamiltonian in the R -matrix interior. We observe that its R -matrix resonance energies and widths are directly related to the poles and residues, respectively, of Hwang’s sum-over-poles representation of cross sections [R.N. Hwang, Nucl. Sci. Eng. 96 (1987) 192].

Given that early-stage oral cavity squamous cell carcinoma (OCSCC) has a high propensity for subclinical nodal metastasis, elective neck dissection has become standard practice for many patients with clinically negative nodes. Unfortunately, for most patients without regional metastasis, this risk-averse treatment paradigm results in unnecessary morbidity. To develop and validate predictive models of occult nodal metastasis from clinicopathological variables that were available after surgical extirpation of the primary tumor and to compare predictive performance against depth of invasion (DOI), the currently accepted standard. This diagnostic modeling study collected clinicopathological variables retrospectively from 7 tertiary care academic medical centers across the US. Participants included adult patients with early-stage OCSCC without nodal involvement who underwent primary surgical extirpation with or without upfront elective neck dissection. These patients were initially evaluated between January 1, 2000, and December 31, 2019. Largest tumor dimension, tumor thickness, DOI, margin status, lymphovascular invasion, perineural invasion, muscle invasion, submucosal invasion, dysplasia, histological grade, anatomical subsite, age, sex, smoking history, race and ethnicity, and body mass index (calculated as weight in kilograms divided by height in meters squared). Occult nodal metastasis identified either at the time of elective neck dissection or regional recurrence within 2 years of initial surgery. Of the 634 included patients (mean [SD] age, 61.2 [13.6] years; 344 men [54.3%]), 114 (18.0%) had occult nodal metastasis. Patients with occult nodal metastasis had a higher frequency of lymphovascular invasion (26.3% vs 8.1%; P < .001), perineural invasion (40.4% vs 18.5%; P < .001), and margin involvement by invasive tumor (12.3% vs 6.3%; P = .046) compared with those without pathological lymph node metastasis. In addition, patients with vs those without occult nodal metastasis had a higher frequency of poorly differentiated primary tumor (20.2% vs 6.2%; P < .001) and greater DOI (7.0 vs 5.4 mm; P < .001). A predictive model that was built with XGBoost architecture outperformed the commonly used DOI threshold of 4 mm, achieving an area under the curve of 0.84 (95% CI, 0.80-0.88) vs 0.62 (95% CI, 0.57-0.67) with DOI. This model had a sensitivity of 91.7%, specificity of 72.6%, positive predictive value of 39.3%, and negative predictive value of 97.8%. Results of this study showed that machine learning models that were developed from multi-institutional clinicopathological data have the potential to not only reduce the number of pathologically node-negative neck dissections but also accurately identify patients with early OCSCC who are at highest risk for nodal metastases.

R -matrix formalism is extended beyond compound nuclear (CN) resonant reactions to include parameterization of direct as well as doorway processes. Direct processes in the R -matrix exterior are parameterized by a unitary matrix that introduces mixing among wave function coefficients of the incoming and outgoing wave function components at the R -matrix channel surface . Doorway processes are parameterized by separating the Hilbert space of the interior R -matrix region into its doorway and CN subspaces, from which doorway state eigenenergies, reduced width amplitudes, and the strengths of their coupling to CN levels appear as new R -matrix parameters. Parameterization of generalized as well as the conventional Reich–Moore approximation for eliminated capture channels in the presence of direct, doorway, and CN processes is presented along with a complex-valued scattering length with contributions from direct, doorway, and CN capture processes. Derivation of Brune’s alternative R -matrix parameters is extended to include doorway states. This work suggests how R -matrix formalism could be extended further by adopting the concepts from related reaction formalisms.

To understand perioperative practices for transoral robotic surgery (TORS) among academic medical centers. An electronic cross-sectional survey was distributed to fellows and program directors participating in 49 American Head and Neck Society fellowships. Operative decisions, medical and swallowing management, and disposition planning were assessed. Thirty-eight responses were collected (77.6%). Twenty-three centers (60.5%) performed > 25 cases annually with the remainder performing fewer. The da Vinci Si was the most commonly used platform ( n  = 28, 73.7%). A majority of institutions advocated tailored resection to adequate margins ( n  = 27, 71.1%) over fixed subunit-based resection ( n  = 11, 28.9%). Most surgeons ( n  = 29, 76.3%) performed neck dissection concurrent with TORS, and 89.5% ( n  = 34) routinely ligated external carotid artery branches. A minority of institutions ( n  = 17, 45.9%) endorsed a standardized TORS care pathway. Antibiotic choices and duration varied, the most common choice being ampicillin/sulbactam ( n  = 21, 55.3%), and the most common duration being 24 h or less ( n  = 22, 57.9%). Multimodal analgesia was used at 36 centers (94.7%), steroids at 31 centers (81.6%), and pharmacologic venous thromboembolic prophylaxis at 29 centers (76.3%). Nasogastric feeding tubes were placed during surgery at 20 institutions (54.1%). Speech-language pathologists routinely performed postoperative swallow evaluations at 29 (78.4%) sites. Practice patterns are variable among institutions performing TORS. While certain surgical and postoperative practices were quite common, many institutions reported no standard TORS care pathway. Further understanding of the impact of individual practices on outcomes is necessary to develop evidence-based perioperative protocols for TORS.

In the update from ENDF/B-VII.1 to ENDF/B-VIII.0, copper cross sections were significantly altered in the intermediate and fast spectrum of the ENDF-VIII.0 library. Performance of this ENDF data requires validation to determine whether recent evaluation has proven beneficial. To examine the performance of the new library, particularly new copper data, critical benchmarks from the ICSBEP handbook were chosen for their sensitivity to copper cross section changes and modeled using SCALE continuous energy Monte Carlo simulations. Selected benchmarks were modeled in ENDF-VII.1 and ENDF-VIII.0 to compute k eff within a statistical uncertainty of 10 pcm and compared in reference to the benchmark experimental criticality. Due to spectrum choices in selection based on the changes to cross section data, the set of benchmarks consist of intermediately enriched uranium, highly enriched uranium, or plutonium systems. 11 separate benchmark evaluations containing 32 individual configurations highly sensitive to copper were selected, modelled, and compared to benchmark experimental criticality. This work demonstrates a significant decrease in the deviation between calculated and experimental criticality as a result of the ENDF-VIII.0 library; a decrease in absolute mean deviation from 522.5±39.3 to 249.6±39.3, and a decrease in root mean square deviation from 630.8±46.1 to 338.1±74.9. Additionally, the role of recently evaluated copper data in this improved agreement is presented, confirming the benefit of reaffirming cross section data.

Conventional nuclear data evaluation methods using generalized linear least squares make the following assumptions: prior and posterior probability distribution functions (PDFs) of all model parameters and data are normal (Gaussian); the linear approximation is sufficiently accurate to minimize the cost function (even for nonlinear models); the model (e.g., of neutron cross section) and experimental data (including covariance data) are without defect and prior PDFs of parameters and measured data are known perfectly. Neglect of covariance between model parameters and measured data in conventional evaluations contributes to imperfections. These assumptions are inherent to the generalized linear least squares minimization method commonly used for resolved resonance region neutron cross section evaluations but are often not justified due to the presence of non-normal PDFs, nonlinear models (e.g., R-matrix formalism), and inherent imperfections in data and models (e.g. imperfect covariance data). Here, these assumptions are removed in a mathematical framework of Bayes’ theorem, which is implemented using the Metropolis-Hastings Monte Carlo method. Most importantly, new parameters are introduced to parameterize discrepancies between the theoretical model and measured data to quantify judgement about discrepancies or imperfections in a reproducible manner. An evaluation of 233 U in the eV region using the ENDF-B/VIII.0 library and transmission data (Guber et al.) is presented, and posterior parameters are compared to those obtained by conventional evaluation methods. This example illustrates the effects of removing the most harmful assumption: that of model-data perfection.

The NEA Data Bank is an international reference centre for computer codes, nuclear and thermochemical data which has traditionally used simple file servers, and even DVDs, to deliver valuable content to end users across the globe. With the recent implementation of a self hosted GitLab system at the NEA it has enabled the Data Bank to streamline delivery, automate processes and testing, while empowering code owners and developers with a secure platform to collaborate and develop codes. In this paper we present the NEA Git- Lab system with some concrete examples of codes such as Kraken, PHITS and FISPACT-II taking advantage of many of the services and functionalities provided by GitLab. We illustrate methodologies on how to work effectively with third party software in a position of being a custodian of code, rather that a code owner, providing DevSecOps as a service.

Laryngeal paragangliomas are an uncommon presentation of head and neck paragangliomas, with laryngeal paragangliomas along with a synchronous paraganglioma being exceptionally rare. We present two challenging cases of laryngeal paragangliomas with extralaryngeal extension, completely resected through a transcervical approach without endolaryngeal disruption, with one case having synchronous bilateral carotid body tumours. Both patients had excellent results with complete tumour resection and no resultant functional impact. The surgical approaches for large laryngeal paraganglioma are discussed with considerations for endolaryngeal, transcervical and combined approaches as well as decision-making when approaching these rare lesions in the setting of synchronous head and neck paragangliomas.