Influence of double-beam design on nuclear waste transmutation performance for CiADS-like reactor

The Japan Atomic Energy Agency is conducting critical experiments to clarify the criticality characteristics of fuel debris using the Static Experiment Critical Facility (STACY). The geometric shape of fuel debris may change, such as joining or separation, due to the unintentional falling of fuel debris or processing during retrieval work. To confirm the validity of simulating these conditions by computations, a series of critical experiments was carried out with two core configurations close to each other. The geometrical change in the fuel debris was simulated by changing the relative distance between the two cores in a core configuration where a small core consisting of 3 × 5 or 5 × 3 fuel rods was close to a larger core with a pit shape to receive it. An experimental analysis was carried out using the Monte Carlo calculation codes MCNP and MVP and the Japanese evaluated nuclear data library JENDL. It was shown that the effective multiplication factor can be evaluated using a simple calculation model, with the calculation results showing that the values of the effective multiplication factor of MCNP were smaller than those of MVP and that the values of the effective multiplication factor of JENDL-4.0 were smaller than those of JENDL-5. In particular, in JENDL-5, it was shown that it is effective to correctly calibrate the temperature point of the thermal scattering law (TSL) used.

The influence of model parameters for the subcritical assembly core of the subcritical nuclear facility "Neutron Source" and uncertainties of nuclear reaction cross sections on the values of the effective neutron multiplication factor is investigated. The analysis is based on numerical simulation using the international software code MCNP 6.2. The possibility of achieving the design nuclear fuel load of 38 fuel assemblies for the subcritical assembly core with the tungsten neutron-generating target is shown with the justification of nuclear safety.

Building on the Coupled Adjoint-based Perturbation Theory for dynAmIcs and heat traNsfer (CAPTAIN) multiphysics framework, this work leverages time-dependent, multiphysics sensitivity coefficients to develop a similarity coefficient framework that analyzes shared nuclear and thermal data uncertainties between various systems under transient conditions. To enable this transient simulation similarity assessment, similarity coefficient analyses are extended from the existing correlation coefficients for the effective multiplication factor to kinetic parameters (effective delayed neutron fraction, prompt neutron generation time, and decay constants), which are used to determine the comprehensive similarity between systemwide parameters (time-dependent power, temperature, etc.). With the simplified examples shown in this work, the CAPTAIN similarity coefficient framework shows excellent agreement with direct perturbations and is ready to be verified with higher-fidelity computational codes to enable rapid uncertainty quantification. These computationally efficient, robust uncertainty quantification methods enable the design of steady-state and transient nuclear experiments to capture the impact of relevant uncertainties, thus increasing confidence in the accuracy of modeling and simulation of scenarios that cannot be experimentally validated due to facility limitations, such as rapid reactivity insertions that lead to elevated temperatures. Furthermore, existing nuclear experiment transient data can be leveraged to assess how effectively the uncertainties in smaller-scale experiments can serve to validate uncertainty in conceptual, advanced nuclear reactor systems.

Age at first birth (AFB) is an important reproductive factor influencing long-term metabolic health. This study aimed to examine the associations between AFB and prevalence of cardiovascular-kidney-metabolic (CKM) syndrome among middle-aged and older US women. US women aged ≥ 40 years at the time of the survey were analyzed using 1999-2018 National Health and Nutrition Examination Survey data. AFB was ascertained via self-report from a reproductive health questionnaire. CKM syndrome was defined using the 2023 American Heart Association criteria. Multivariate logistic regression models, restricted cubic spline analysis, and subgroup analysis were used for statistical analyses. Among 6840 women (mean age 63 years; mean AFB 22 years) included, restricted cubic spline curve showed a U-shaped association between AFB and CKM syndrome prevalence, with the nadir at AFB = 24 years. The odds ratios (95% confidence intervals) per 1-year increase in AFB were 0.878 (0.817-0.944) for participants with AFB < 24 years and 1.019 (0.949-1.095) for those with AFB > 24 years. Compared with the reference group (AFB 24-29 years), women with AFB < 18 years had 86.3% higher odds of CKM syndrome. Subgroup analysis revealed a stronger association between AFB and the odds of CKM syndrome among premenopausal women (p for interaction = 0.023). Early AFB < 24 years is associated with a higher likelihood of CKM syndrome in US women aged ≥ 40 years, especially among premenopausal women. Prospectively designed cohort studies are needed to establish AFB as an important factor for mid- to late-life CKM health.

Validation of ENDF/B-VIII.0 and NCrystal thermal scattering laws for graphite in criticality safety analysis using OpenMC

North Carolina's robust tobacco industry faces a new threat from Meloidogyne enterolobii, the guava root-knot nematode, which was first identified in the state in 2011. This species can overcome host resistance in tobacco that is effective in managing other root-knot nematode (RKN) species such as M. incognita. Novel sources of host resistance are therefore needed for this pathogen. This study evaluated potential tobacco host resistance to M. enterolobii through a series of greenhouse bioassays. Genotypes of Nicotiana tabacum and other Nicotiana species (n=84) were assayed for response to M. enterolobii. Materials were selected to represent commercially important cultivars, resistance to other RKN species, resistance to other plant-parasitic nematodes and pathogens, genetic diversity, and those carrying introgressed chromosomal segments from wild Nicotiana relatives. Plants were inoculated with 10,000 eggs per plant of a North Carolina isolate of M. enterolobii and eggs from resultant infections were extracted 60 days post inoculation. Data were collected for eggs per gram of root and root galling severity. Resistance and susceptibility were quantified by calculating each line's reproductive factor (RF, final population/initial population). All materials were assessed for response through two independent bioassay trials, and genotypes displaying resistance were subsequently retested in replicates of ten in a confirmation screening. Six genotypes of wild Nicotiana species were found to be either highly resistant or moderately resistant to M. enterolobii. These lines may offer useful germplasm for future resistance breeding efforts and further characterization of resistance in Nicotiana to M. enterolobii.

Fragile X-related protein 1 (FXR1) is an m6A-binding protein that plays a critical role in cancer development and progression. It has unclear associations between its genetic variants and breast cancer (BC) susceptibility. This study explored correlations of FXR1 single nucleotide polymorphisms (SNPs) with BC susceptibility. A frequency matching case-control study included 802 histologically confirmed BC cases and 802 age-matched controls (± 2 years) of Han-Chinese ethnicity. Four FXR1 SNPs were selected using bioinformatics. Associations with BC risk and reproductive factor interactions were assessed using conditional logistic regression. FXR1 expression was evaluated by quantitative real-time PCR (qRT-PCR), with RNA structural and miRNA-binding changes predicting using RNAfold and miRNASNP. The m6A-related target genes were identified by QTLbase and RMBase. Tissue expression analyzed via GEPIA. The FXR1 rs2601 A > G variant was significantly associated with reduced BC risk, confirmed by stratification. For rs2601, the said polymorphism exhibited association with the reduced incidence with BC in specific subgroups of studied cohort when comparison was conducted between homozygous wild type AA and AG + GG genotypes. Haplotype analysis revealed the haplotype Ars1058382Ars1805607Ars2601Trs6799476 and Trs1058382Ars1805607Grs2601Trs6799476 is probably protective to the incidence of BC in this population. Additionally, a significant additive interaction was observed between rs2601 and age at menarche. qRT-PCR showed genotype-dependent FXR1 expression. Integrative analysis identified 10 candidate associated genes, among which CCDC39 was downregulated in BC tissues(P < 0.01). The FXR1 rs2601 A > G is probably protective to BC among Han Chinese women and it has an interaction with reproductive factors. This could provide theoretical basis for BC screening and prevention.

Systemic inflammatory conditions affect many women during their reproductive years and tumor necrosis factor inhibitors (TNFi) are one of the most common biologic classes used to help manage disease in this population. Although treatment guidelines now recommend continuing TNFi in pregnancy, studies examining recent real-world treatment trends in this population are limited. The objective of this study was to describe TNFi treatment patterns in the peripregnancy period among patients treated with TNFi before pregnancy, and to describe differences by autoimmune condition, over time. A retrospective cohort study was conducted using two US administrative health insurance claims databases: Merative MarketScan Commercial Database (CCAE) and Merative MarketScan Multi-State Medicaid Database (MDCD) between 2010 and 2022. Participants were pregnant women aged 18 to 49 years with ≥1 dispensing for TNFi in the six months before pregnancy start and a diagnosis of psoriasis (PSO), psoriatic arthritis (PsA), ulcerative colitis (UC) or Crohn's disease (CD), and/or rheumatoid arthritis (RA). There were 6,031 pregnancies (5,025 women) in CCAE and 825 pregnancies (714 women) in MDCD included. Continuation in pregnancy was highest in UC or CD (89.3% in CCAE and 84.0% in MDCD), followed by RA (71.9% in CCAE and 71.9% in MDCD), and PSO/PsA (66.6% in CCAE and 65.7% in MDCD). Across all conditions, the proportion continuing TNFi significantly increased over time (P < 0.01). This study extends our understanding of peripregnancy TNFi treatment patterns in women with autoimmune diseases, illustrating an increasing trend of TNFi continuation in pregnancy across two administrative data sources in the United States.

We generalise the popular cops and robbers game to multi-layer graphs, where each cop and the robber are restricted to a single layer (or set of edges). We show that initial intuition about the best way to allocate cops to layers is not always correct, and prove that the multi-layer cop number is neither bounded from above nor below by any increasing function of the cop numbers of the individual layers. We determine that it is NP-hard to decide if $k$ cops are sufficient to catch the robber, even if every cop layer is a tree and a set of isolated vertices. However, we give a polynomial time algorithm to determine if $k$ cops can win when the robber layer is a tree. Additionally, we investigate a question of worst-case divisions of a simple graph into layers: given a simple graph $G$, what is the maximum number of cops required to catch a robber over all multi-layer graphs where each edge of $G$ is in at least one layer and all layers are connected? For cliques, suitably dense random graphs, and graphs of bounded treewidth, we determine this parameter up to multiplicative constants. Lastly we consider a multi-layer variant of Meyniel's conjecture, and show the existence of an infinite family of graphs whose multi-layer cop number is bounded from below by a constant times $n / \log n$, where $n$ is the number of vertices in the graph.

Chlamydia trachomatis has evolved sophisticated mechanisms to manipulate key host cell signaling pathways to facilitate its intracellular reproduction. N6-methyladenosine (m6A) in RNA is known to regulate various physiological and disease processes, and is also involved in the regulation of pathogenic and developmental processes in many pathogens. However, the specific impact of m6A modification on the intracellular growth of C. trachomatis remains poorly understood. In this study, our analysis of the m6A methylation profiles of host cell mRNAs following C. trachomatis infection revealed significant alterations in the distribution of m6A modifications, methylation motifs, and m6A-modified host target genes. We further demonstrate that chlamydial intracellular reproduction is mediated by the host methyltransferase-like (METTL) enzyme METTL14. Silencing METTL14 significantly reduced the reproduction efficiency of C. trachomatis. Mechanistically, C. trachomatis activates the Mitogen-Activated Protein Kinase (MAPK) and Phosphatidylinositol 3-kinase/Protein Kinase B (PI3K/AKT) signaling pathways through METTL14, thereby inhibiting host cell apoptosis and promoting intracellular bacterial reproduction. Collectively, these findings identify METTL14 as a key host factor for chlamydial intracellular reproduction, providing new mechanistic insights and potential targets for therapeutic intervention.

The fallopian tube epithelium (FTE) is the primary tissue of origin for ovarian high-grade serous carcinoma (HGSC), with ovulation implicated as a key risk factor. TP53 mutations, a hallmark of HGSC and its precursor lesions, such as p53 signature, are predominantly CG>TA substitutions attributed to cytidine deamination. We previously demonstrated that ovulatory follicular fluid (FF) released reactive oxygen species (ROS), which activate activation-induced cytidine deaminase (AID) and promote TP53 mutagenesis in FTE. Here, we demonstrate that hemoglobin (Hb) originating from retrograde menstruation acts as an extracellular ROS scavenger, attenuating AID-mediated TP53 deamination in fallopian tube fimbriae, both in vitro and in vivo. Peritoneal fluid from tubal-ligated women exhibited significantly lower Hb, higher ROS, and elevated hypoxanthine phosphoribosyl transferase (HPRT) mutagenic activity compared to nonligated controls (p < 0.004). Histopathological analysis of 206 fallopian tubes from 119 women undergoing opportunistic salpingectomy further revealed a significantly higher frequency of p53 signatures in ligated tubes (0.22 ± 0.64 lesions per fimbria) than in nonligated tubes (0.07 ± 0.31 lesions per fimbria) (p = 0.017). Multivariate analysis identified tubal ligation as the sole reproductive factor independently associated with p53 signatures [odds ratio (OR) = 3.32; 95% CI: 1.15-9.57]. Our findings indicate that retrograde menstrual Hb mitigates ovulation-associated ROS stress, thereby reducing AID-mediated TP53 mutagenesis in the FTE. This study uncovers a physiological, protective role for menstruation against ovulatory oxidative damage and its mutagenic consequences, while demonstrating that tubal ligation disrupts this endogenous antioxidant mechanism, resulting in an increased burden of p53 signature lesions. © 2026 The Pathological Society of Great Britain and Ireland.

This study evaluates the neutronic performance of 12 reflector materials [Ba2Pb, BeO, graphite, lead, magnesium, MgO, PbO, PbS, SiC, Zr3Si2, ZrC, and Yttria-stabilized Zirconia (YSZ)] in a lead-cooled fast reactor (LFR) using OpenMC with the ENDF/B-VIII.0 nuclear data library. The materials are assessed for their impact on the effective multiplication factor (keff), neutron leakage, neutron flux and fission rate distributions, burnup, and activation products. BeO exhibited superior performance, achieving the highest keff, lowest neutron leakage, and longest fuel cycle length due to its low capture cross section and high (n, 2n) reaction rate. Other materials, such as MgO and graphite, also performed strongly, while in contrast, materials like Ba2Pb and lead showed higher leakage and nonuniform flux distributions, limiting their suitability. BeO resulted in the highest minor actinide activity, whereas Ba2Pb yielded the lowest. These findings address a key gap in LFR reflector performance, positioning BeO as the top neutronic performer, followed by MgO and graphite in a parametric neutronics study. However, such strong moderators significantly soften the neutron spectrum, shifting the system toward a more thermalized regime. Practical implementation will also require addressing material-specific challenges (e.g. toxicity, cost, and coolant compatibility).

ABSTRACT Formal national policy documents are key instruments for enhancing state governance capacity. Differential textual adjustments made by local governments at different administrative tiers to central documents – i.e. policy content reproduction – can lead to heterogeneous implementation and thereby affect policy outcomes. Using China’s Role Model City for Safe Development policy, initiated in 2010, as a case, this paper employs an LDA-based weighted approach to compare the extent and driving factors of content updating and elaboration by prefectural and provincial governments, thus contributing to the existing literature. The study finds a structurally differentiated pattern in the drivers of policy content reproduction – ‘similarity in form, divergence in substance’ – between the two tiers. Both are jointly pulled by pressure from production accidents and signals in central policy documents, yet they diverge markedly with respect to factors such as per capita GDP and fiscal self-sufficiency. The study further confirms a U-shaped relationship between prefectural policy adoption speed and the level of policy content reproduction, with a turning point at 0.81 years. This study proposes a conceptual analytical framework for understanding central – local differences in policy texts and their operating mechanisms, and provides empirical evidence to inform the formulation of context-appropriate strategies for enhancing urban safety and resilience. Highlights A weighted latent Dirichlet allocation topic-model captures the policy content reproduction. Policy content reproduction differs between provincial and prefectural governments. Central signals and accident pressure shape urban safety policy texts. Prefectural adoption speed shows a U-shaped pattern in policy content reproduction. Provincial fiscal autonomy supports stronger adaptation of central texts.

The HTR-10 was used as a representative pebble-bed high-temperature gas-cooled reactor in this assessment of nuclear data’s impact on important reactor and spent fuel metrics, including safety-related quantities such as the effective multiplication factor (keff), temperature reactivity feedback, spent fuel inventory, and decay heat. Using the SCALE code system tools and ENDF/B-VII.1 nuclear data libraries, we quantify the effect of nuclear data uncertainties on these key performance metrics for both fresh fuel and equilibrium core configurations. For reactor core key parameters, important contributors to uncertainty include reactions of 235U [ ν ˉ , fission, (n, γ)], 238U [elastic, (n, γ)], and graphite [elastic, (n, γ)]. Additional important contributors for the equilibrium core include reactions of higher actinides (239Pu, 240Pu) and fission products (135Xe, 149Sm). For spent fuel analysis, most nuclide inventory uncertainties remain below 5%. Higher uncertainties up to 11% are being observed for minor actinides like 243Am and 244Cm. Additionally, fission product uncertainties in 155Eu and 155Gd, of 25% and 23% respectively, are also significant and have implications for burnup credit applications. 110mAg also shows high uncertainty of up to 11%, mainly due to fission product yield uncertainties. Decay heat relative uncertainties remain below 0.6% up to 10 years’ cooling time after fuel discharge. The highest relative uncertainty of 1.5% occurs at 500 years of cooling; however, because the decay heat value is very low at that time, the absolute uncertainty is not significant. This work demonstrates that extending assessments beyond fresh fuel keff to include irradiated cores, nuclide inventories, and decay heat is essential in understanding the behavior of uncertainties as a function of fuel burnup and can support improvements of safety margins and spent fuel management.

In sensitivity analysis, adjoint methods are the most efficient for complex systems with many input parameters and few output responses, such as reactor physics problems. In this context, this work presents an adjoint sensitivity analysis method for a one-dimensional model of a stationary neutronics–thermal hydraulics–coupled molten salt reactor (MSR), using the Lagrangian formalism most commonly used in the field of optimization. Focusing on the specific case of a response function dependent only on the effective multiplication factor keff (such as the reactivity), the model is implemented numerically in Python. The results are discussed using molten salt fast reactor data. The adjoint problem is solved through a partitioned scheme. In particular, the singular adjoint neutronics problem is solved using eigenvalue shifting. Various adjoint sensitivities are evaluated and are found to agree with reference finite differences calculations, showing the potential of adjoint methods for the multiphysics of MSRs. As calculating partial derivatives is complex and error prone, automatic differentiation should be considered in future work.

Vegetable production in Georgia faces significant challenges from different diseases and pests and one of them is root-knot nematodes (Meloidogyne spp.). In a recent statewide survey in major vegetable-growing regions in Georgia, two Meloidogyne species, guava root-knot nematode (M. enterolobii) and peach root-knot nematode (M. floridensis), were detected for the first time in addition to the commonly occurring southern root-knot nematode, M. incognita. Despite their emerging significance, comparative data on the reproductive capabilities of these recently detected species on key vegetable crops are lacking. This study evaluated the reproduction potential of M. enterolobii, M. floridensis, and M. incognita on eight economically important vegetable crops in Georgia: beet, broccoli, cabbage, cantaloupe, pepper, snap bean, squash, and tomato. Reproduction factor (final population/initial inoculum), galling index, and number of eggs per gram of root were quantified for each species in each vegetable crop. All Meloidogyne species reproduced in the tested vegetable crops in this study. In most experiments, M. enterolobii exhibited significantly higher Rf, galling indices, and egg counts per gram of root compared to M. incognita and M. floridensis across the majority of tested vegetable crops, with the exception of squash and tomato. On these two crops, all three species showed comparable values for the measured parameters. These findings highlight the high reproductive capacity and pathogenic potential of M. enterolobii on a broad range of vegetable hosts. Based on these findings, we hypothesize that in mixed-species populations within infested vegetable fields, M. enterolobii may become the predominant species due to its superior reproductive performance.

Management of the reniform nematode (Rotylenchulus reniformis Linford and Oliveira) in upland cotton (Gossypium hirsutum L.) continues to be a challenge primarily due to inconsistent performance of resistant genotypes. We hypothesize that diversity in reproduction and virulence in R. reniformis has contributed to the inconsistent performance of resistant cotton genotypes. Rotylenchulus reniformis isolates from Tennessee (TN), Alabama (AL), Mississippi (MS), Texas (TX), Louisiana (LA), Arkansas (AR), Florida (FL), South Carolina (SC) and Georgia (GA) were assessed for their reproduction and virulence on a resistant cultivar DP 2141NR B3XF and a susceptible cultivar DP 2317 B3TXF. The AR isolate had the greatest reproduction factor (Rf) of 19.7, while the AL isolate had the least Rf of 3.3. Rfs of other isolates were intermediate. Up to 85% of reproductions were suppressed by the resistant cultivar relative to the susceptible cultivar. While plants inoculated with nematodes had lower root biomass than the non-inoculated control, the degree of root biomass reduction varied by isolate, suggesting differing levels of virulence among R. reniformis isolates. The AR isolate reproduced the most and was the most virulent. The AL isolate reproduced the least and was less virulent. The AR, MS, TN and LA isolates were the top four reproducing isolates, probably indicating a greater suitability of the Delta region for nematode reproduction. The correlation analysis indicated that up to 85% variation in plant biomasses was explained by nematode reproduction. These results suggest that resistance breeding programs in cotton must consider the diversity in R. reniformis.

Between 2014 and 2024, unhatched eggs from several wild bird species were analyzed at the Center for Analysis and Diagnosis of Wildlife (CAD, Spain), including eggs from threatened species such as the bearded vulture (Gypaetus barbatus) and the Spanish imperial eagle (Aquila adalberti). The aim of this study was to characterize exposure of wild birds to environmental contaminants and discuss their potential implications for reproduction. To this end, eggs were subjected to detailed examination, including biometric measurements, evaluation of embryonic development, and investigation of possible causes of reproductive failure. In addition, chemical analyses were performed on eggshells and egg contents to detect residues of different groups of xenobiotics, including metals, pesticides, pharmaceutical compounds and polychlorinated biphenyls (PCBs). Several contaminants were detected in the analyzed samples, mainly persistent organochlorine compounds such as DDT degradation products (o,p'-DDE and p,p'-DDE) and PCBs. Residues of currently used pesticides, including pyrethroids and fipronil, were also identified in some samples, whereas pharmaceutical residues were not detected during the study period. Although most contaminant concentrations were relatively low, their persistence, potential sublethal effects, and the simultaneous presence of multiple compounds in the same sample suggest that chemical exposure could represent a potential risk factor for avian reproduction. The results highlight the value of wild bird eggs as bioindicators of environmental contamination and emphasize the importance of long-term toxicological monitoring, particularly for species of conservation concern characterized by long lifespans and low reproductive rates.

We study non-Hermitian random matrices belonging to the symmetry classes of the complex and symplectic Ginibre ensemble, and present a unifying and systematic framework for analysing mixed spectral moments involving both holomorphic and anti-holomorphic parts. For weight functions that induce a recurrence relation of the associated planar orthogonal polynomials, we derive explicit formulas for the spectral moments in terms of their orthogonal norms. This includes exactly solvable models such as the elliptic Ginibre ensemble and non-Hermitian Wishart matrices. In particular, we show that the holomorphic spectral moments of complex non-Hermitian random matrices coincide with those of their Hermitian limit up to a multiplicative constant, determined by the non-Hermiticity parameter. Moreover, we show that the spectral moments of the symplectic non-Hermitian ensemble admit a decomposition into two parts: one corresponding to the complex ensemble and the other constituting an explicit correction term. This structure closely parallels that found in the Hermitian setting, which naturally arises as the Hermitian limit of our results. Within this general framework, we perform a large-N asymptotic analysis of the spectral moments for the elliptic Ginibre and non-Hermitian Wishart ensemble, revealing the mixed moments of the elliptic and non-Hermitian Marchenko–Pastur laws. Furthermore, for the elliptic Ginibre ensemble, we employ a recently developed differential operator method for the associated correlation kernel, to derive an alternative explicit formula for the spectral moments and obtain their genus-type large-N expansion.