Agent-based models (ABMs) are powerful for simulating detailed infectious disease dynamics, but they are computationally intensive, limiting parameter inference. We present a Bayesian history matching approach with Gaussian process emulation to efficiently calibrate an ABM of SARS-CoV-2 transmission in Norway, enabling inference of numerous parameters and reducing computational costs.We apply this technique to model the emergence and subsequent winter wave of the Omicron BA.1/BA.2 variants in Norway from September 2021 to April 2022. By fitting age-specific hospitalisation data, we infer 15 key parameters, including age-specific susceptibility, variant transmissibility, and the infection-hospitalisation ratio. The calibrated model accurately reproduces epidemic curves and provides insights into Omicron’s spread.We estimate that around 60% of the Norwegian population was infected with Omicron BA.1/BA.2 during the 2021/2022 winter wave. The model suggests the variant circulated in Norway before its detection in South Africa in late November 2021. Our findings indicate that Omicron’s transmission advantage over Delta was primarily due to immune evasion rather than a substantial increase in intrinsic transmissibility. Counterfactual scenarios reveal the critical role of the November 2021 booster vaccine rollout in mitigating the ensuing winter wave, indicating near-optimal timing for balancing immunisation and waning. Our estimates also suggest that the December 2021 interventions had limited impact beyond altering general mobility.This study demonstrates the power of combining ABMs with advanced calibration to derive detailed epidemiological insights from limited data. Efficiently fitting parameters enables comprehensive epidemic modelling. Emulator-based calibration greatly enhances ABMs’ utility for retrospective analysis and real-time decision support during outbreaks, providing a valuable tool for public health planning and response.

Assessing traffic patterns is important for many applications such as rush hour traffic management, cross-border commuting statistics, transportation disruption assessment, and crisis management. We present a method for detecting commuting patterns from time-detailed traffic sensor data. Our method uses Gaussian mixture models to identify morning peaks that also exhibit expected variation patterns over weekends and holidays as corresponding to commuting. We apply the method to detect the variation in commuting between countries in the Nordics during the disruptions caused by the COVID-19 pandemic. Results show that the commuting traffic experienced a smaller decrease (42–71

Vaccination was a key intervention in controlling the COVID-19 pandemic globally. In early 2021, Norway faced significant regional variations in COVID-19 incidence and prevalence, with large differences in population density, necessitating efficient vaccine allocation to reduce infections and severe outcomes. This study explored alternative vaccination strategies to minimize health outcomes (infections, hospitalizations, ICU admissions, deaths) by varying regions prioritized, extra doses prioritized, and implementation start time. Using two models (individual-based and meta-population), we simulated COVID-19 transmission during the primary vaccination period in Norway, covering the first 7 months of 2021. We investigated alternative strategies to allocate more vaccine doses to regions with a higher force of infection. We also examined the robustness of our results and highlighted potential structural differences between the two models. Our findings suggest that early vaccine prioritization could reduce COVID-19 related health outcomes by 8% to 20% compared to a baseline strategy without geographic prioritization. For minimizing infections, hospitalizations, or ICU admissions, the best strategy was to initially allocate all available vaccine doses to fewer high-risk municipalities, comprising approximately one-fourth of the population. For minimizing deaths, a moderate level of geographic prioritization, with approximately one-third of the population receiving doubled doses, gave the best outcomes by balancing the trade-off between vaccinating younger people in high-risk areas and older people in low-risk areas. The actual strategy implemented in Norway was a two-step moderate level aimed at maintaining the balance and ensuring ethical considerations and public trust. However, it did not offer significant advantages over the baseline strategy without geographic prioritization. Earlier implementation of geographic prioritization could have more effectively addressed the main wave of infections, substantially reducing the national burden of the pandemic.

BACKGROUND:The global incidence target for the elimination of hepatitis C among people who inject drugs (PWID) is <2/100. In Norway, the hepatitis C epidemic is concentrated in PWID. Immigrants are the second most important risk group for chronic infection. We modelled the incidence of hepatitis C among active PWID, and the prevalence of chronic infection among active PWID, ex-PWID, and immigrants in Norway to 2022. METHODS:We built a stochastic compartmental model, which was informed using data from national data sources, literature, and expert opinion. We report median values with 95% credible intervals (CrI). RESULTS:The model estimated 30 (95% Crl, 13-52) new infections among active PWID in 2022, or 0.37/100 (95% Crl, 0.17-0.65), down from a peak of 726 (95% Crl, 506-1067) in 2000. Across all groups, the model estimated 3202 (95% Crl, 1273-6601) chronically infected persons in 2022. Results were robust in sensitivity analyses. CONCLUSIONS:Norway provides an example of the feasibility of hepatitis C elimination in a setting with a concentrated epidemic, high coverage of harm reduction services, and no treatment restrictions. Continued momentum is needed to further reduce the transmission and burden of hepatitis C in Norway.

Massive stars are a major source of chemical elements in the cosmos, ejecting freshly produced nuclei through winds and core-collapse supernova explosions into the interstellar medium. Among the material ejected, long-lived radioisotopes, such as 60Fe (iron) and 26Al (aluminum), offer unique signs of active nucleosynthesis in our galaxy. There is a long-standing discrepancy between the observed 60Fe/26Al ratio by γ-ray telescopes and predictions from supernova models. This discrepancy has been attributed to uncertainties in the nuclear reaction networks producing 60Fe, and one reaction in particular, the neutron-capture on 59Fe. Here we present experimental results that provide a strong constraint on this reaction. We use these results to show that the production of 60Fe in massive stars is higher than previously thought, further increasing the discrepancy between observed and predicted 60Fe/26Al ratios. The persisting discrepancy can therefore not be attributed to nuclear uncertainties, and points to issues in massive-star models.

Restrictions of cross-border mobility are typically used to prevent an emerging disease from entering a country in order to slow down its spread. However, such interventions can come with a significant societal cost and should thus be based on careful analysis and quantitative understanding on their effects. To this end, we model the influence of cross-border mobility on the spread of COVID-19 during 2020 in the neighbouring Nordic countries of Denmark, Finland, Norway and Sweden. We investigate the immediate impact of cross-border travel on disease spread and employ counterfactual scenarios to explore the cumulative effects of introducing additional infected individuals into a population during the ongoing epidemic. Our results indicate that the effect of inter-country mobility on epidemic growth is non-negligible essentially when there is sizeable mobility from a high prevalence country or countries to a low prevalence one. Our findings underscore the critical importance of accurate data and models on both epidemic progression and travel patterns in informing decisions related to inter-country mobility restrictions.

The $\ensuremath{\gamma}$-strength function and the nuclear level density for the odd-odd, rare-earth nucleus $^{166}\mathrm{Ho}$ have been extracted from $^{163}\mathrm{Dy}(\ensuremath{\alpha},p\ensuremath{\gamma})^{166}\mathrm{Ho}$ data using the Oslo method. A structure at $\ensuremath{\approx}3$ MeV in the $\ensuremath{\gamma}$-strength function is interpreted as the $M1$ scissors resonance. By employing three different methods we find that its strength depends rather strongly on the modeling of the $E1$ strength, while its centroid does not. The $^{166}\mathrm{Ho}$ scissors resonance parameters are consistent with previous results on other rare-earth nuclei.

The gamma-strength function and the nuclear level density for the odd-odd, rare-earth nucleus 166Ho have been extracted from 163Dy(alpha, p gamma )166Ho data using the Oslo method. A structure at P-'3 MeV in the gamma-strength function is interpreted as the M1 scissors resonance. By employing three different methods we find that its strength depends rather strongly on the modeling of the E1 strength, while its centroid does not. The 166Ho scissors resonance parameters are consistent with previous results on other rare-earth nuclei.

Background: Given the societal, economic and health costs of COVID-19 non-pharmaceutical interventions (NPI), it is important to assess their effects. Human mobility serves as a surrogate measure for human contacts and compliance with NPI. In Nordic countries, NPI have mostly been advised and sometimes made mandatory. It is unclear if making NPI mandatory fur-ther reduced mobility. Aim: We investigated the effect of non-compulsory and follow-up mandatory meas-ures in major cities and rural regions on human mobil-ity in Norway. We identified NPI categories that most affected mobility. Methods: We used mobile phone mobility data from the largest Norwegian operator. We analysed non-compulsory and mandatory measures with before-after and synthetic difference-in -differ-ences approaches. By regression, we investigated the impact of different NPI on mobility. Results: Nationally and in less populated regions, time travelled, but not distance, decreased after follow-up mandatory meas-ures. In urban areas, however, distance decreased after follow-up mandates, and the reduction exceeded the decrease after initial non-compulsory measures. Stricter metre rules, gyms reopening, and restau-rants and shops reopening were significantly associ-ated with changes in mobility. Conclusion: Overall, distance travelled from home decreased after non -compulsory measures, and in urban areas, distance further decreased after follow-up mandates. Time travelled reduced more after mandates than after non-compulsory measures for all regions and inter-ventions. Stricter distancing and reopening of gyms, restaurants and shops were associated with changes in mobility.

In this work, we present new data on the $^{182,183,184}$W($\gamma,n$) cross sections, utilizing a quasi-monochromatic photon beam produced at the NewSUBARU synchrotron radiation facility. Further, we have extracted the nuclear level density and $\gamma$-ray strength function of $^{186}$W from data on the $^{186}$W($\alpha,\alpha^\prime\gamma$)$^{186}$W reaction measured at the Oslo Cyclotron Laboratory. Combining previous measurements on the $^{186}$W($\gamma,n$) cross section with our new $^{182,183,184}$W($\gamma,n$) and ($\alpha,\alpha^\prime\gamma$)$^{186}$W data sets, we have deduced the $^{186}$W $\gamma$-ray strength function in the range of $1<E_\gamma<6$ MeV and $7<E_\gamma<14$ MeV. Our data are used to extract the level density and $\gamma$-ray strength functions needed as input to the nuclear-reaction code \textsf{TALYS}, providing an indirect, experimental constraint for the $^{185}$W($n,\gamma$)$^{186}$W cross section and reaction rate. Compared to the recommended Maxwellian-averaged cross section (MACS) in the KADoNiS-1.0 data base, our results are on average lower for the relevant energy range $k_B T \in [5,100]$ keV, and we provide a smaller uncertainty for the MACS. The theoretical values of Bao \textit{et al.} and the cross section experimentally constrained on photoneutron data of Sonnabend \textit{et al.} are significantly higher than our result. The lower value by Mohr \textit{et al.} is in very good agreement with our deduced MACS. Our new results could have implications for the $s$-process and in particular the predicted $s$-process production of $^{186,187}$Os nuclei.

The COVID-19 pandemic is challenging nations with devastating health and economic consequences. The spread of the disease has revealed major geographical heterogeneity because of regionally varying individual behaviour and mobility patterns, unequal meteorological conditions, diverse viral variants, and locally implemented non-pharmaceutical interventions and vaccination roll-out. To support national and regional authorities in surveilling and controlling the pandemic in real-time as it unfolds, we here develop a new regional mathematical and statistical model. The model, which has been in use in Norway during the first two years of the pandemic, is informed by real-time mobility estimates from mobile phone data and laboratory-confirmed case and hospitalisation incidence. To estimate regional and time-varying transmissibility, case detection probabilities, and missed imported cases, we developed a novel sequential Approximate Bayesian Computation method allowing inference in useful time, despite the high parametric dimension. We test our approach on Norway and find that three-week-ahead predictions are precise and well-calibrated, enabling policy-relevant situational awareness at a local scale. By comparing the reproduction numbers before and after lockdowns, we identify spatially heterogeneous patterns in their effect on the transmissibility, with a stronger effect in the most populated regions compared to the national reduction estimated to be 85% (95% CI 78%-89%). Our approach is the first regional changepoint stochastic metapopulation model capable of real time spatially refined surveillance and forecasting during emergencies.

Change in nuclei deformation leads to changes in statistical properties such as the nuclear level density (NLD) and γ-ray strength function (γSF). The NLD and γSF of 151Sm were extracted using the Oslo method. The strength of the scissors resonance (SR) and its centroid energy for 151Sm were found to be 2.13 ± 0.60 μN2 and 2.48 ± 0.25 MeV, respectively. These results were used to place the SR of 151Sm and its magnetic dipole strength B(M1)SR into the context of previously measured Sm isotopes.

In this work, we present new data on the $^{182,183,184}\mathrm{W}(\ensuremath{\gamma},n$) cross sections, utilizing a quasi-monochromatic photon beam produced at the NewSUBARU synchrotron radiation facility. Further, we have extracted the nuclear level density and $\ensuremath{\gamma}$-ray strength function of $^{186}\mathrm{W}$ from data on the $^{186}\mathrm{W}(\ensuremath{\alpha},{\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{\gamma})^{186}\mathrm{W}$ reaction measured at the Oslo Cyclotron Laboratory. Combining previous measurements on the $^{186}\mathrm{W}(\ensuremath{\gamma},n$) cross section with our new $^{182,183,184}\mathrm{W}(\ensuremath{\gamma},n$) and ($\ensuremath{\alpha},{\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{\gamma})^{186}\mathrm{W}$ data sets, we have deduced the $^{186}\mathrm{W}\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray strength function in the range of $1<{E}_{\ensuremath{\gamma}}<6$ MeV and $7<{E}_{\ensuremath{\gamma}}<14$ MeV. Our data are used to extract the level density and $\ensuremath{\gamma}$-ray strength functions needed as input to the nuclear-reaction code talys, providing an indirect, experimental constraint for the $^{185}\mathrm{W}(n,\ensuremath{\gamma})^{186}\mathrm{W}$ cross section and reaction rate. Compared to the recommended Maxwellian-averaged cross section (MACS) in the KADoNiS-1.0 database, our results are on average lower for the relevant energy range ${k}_{B}T\ensuremath{\in}[5,100]$ keV, and we provide a smaller uncertainty for the MACS. The theoretical values of Bao et al. [At. Data Nucl. Data Tables 76, 70 (2000)] and the cross section experimentally constrained on photoneutron data of Sonnabend et al. [Astrophys. J. 583, 506 (2003)] are significantly higher than our result. The lower value by Mohr et al. [Phys. Rev. C 69, 032801(R) (2004)] is in very good agreement with our deduced MACS. Our new results provide an improved uncertainty estimate for the ($n,\ensuremath{\gamma})^{186}\mathrm{W}$ reaction rate, which is one important ingredient in simulations for investigating the neutron density and the $^{186,187}\mathrm{Os}$ production in the $s$ process.

In this work, we present new data on the 182,183,184W(& gamma; , n) cross sections, utilizing a quasi-monochromatic photon beam produced at the NewSUBARU synchrotron radiation facility. Further, we have extracted the nuclear level density and & gamma; -ray strength function of 186W from data on the 186W(& alpha;, & alpha;'& gamma; ) 186W reaction measured at the Oslo Cyclotron Laboratory. Combining previous measurements on the 186W(& gamma; , n) cross section with our new 182,183,184W(& gamma; , n) and (& alpha;, & alpha;'& gamma; ) 186W data sets, we have deduced the 186W & gamma; -ray strength function in the range of 1 < E & gamma; < 6 MeV and 7 < E & gamma; < 14 MeV. Our data are used to extract the level density and & gamma; -ray strength functions needed as input to the nuclear-reaction code TALYS, providing an indirect, experimental constraint for the 185W(n, & gamma; ) 186W cross section and reaction rate. Compared to the recommended Maxwellian-averaged cross section (MACS) in the KADoNiS-1.0 database, our results are on average lower for the relevant energy range kBT & ISIN; [5, 100] keV, and we provide a smaller uncertainty for the MACS. The theoretical values of Bao et al. [At. Data Nucl. Data Tables 76, 70 (2000)] and the cross section experimentally constrained on photoneutron data of Sonnabend et al. [Astrophys. J. 583, 506 (2003)] are significantly higher than our result. The lower value ingredient in simulations for investigating the neutron density and the 186,187Os production in the s process.

We present the first experimental evidence of the scissors mode in the superheavy nucleus 254 No produced in the 208 Pb( 48 Ca, 2 n γ )) 254 No reaction. The spectrum of γ rays emitted by the excited 254 No nuclei shows an enhanced γ -ray yield for transition energies of ≈ 2 . 5 MeV. By measuring the linear polarization properties of the emitted γ rays, we confirm that the transitions in the enhancement region are predominantly of magnetic-dipole character, characteristic for the scissors mode. To further characterize the enhanced γ -ray yield, simulations of the electromagnetic decay of 254 No were performed. The observed enhancement is reproduced by including an M 1 component in the γ strength function with total strength B ( M 1 ↑ ) = 11 . 8 ( 19 ) μ 2 N . This is in good agreement with the integrated M 1 strength from sum-rule estimates and new calculations within the quasi-particle random-phase approximation presented here. Our results provide a stringent test of phenomenological formulae for the scissors mode currently used in stellar nucleosynthesis calculations. We find that those formulae are not satisfactory, and we recommend using sum-rule estimates assuming a rigid-body moment of inertia instead for describing the scissors mode in superheavy nuclei.

M. Guttormsen,1, ∗ K. O. Ay,2 M. Ozgur,2 E. Algin,2, 3 A. C. Larsen,1 F. L. Bello Garrote,1 H. C. Berg,1, † L. Crespo Campo,1 T. Dahl-Jacobsen,1 F. W. Furmyr,1 D. Gjestvang,1 A. Görgen,1 T. W. Hagen,1 V. W. Ingeberg,1 B. V. Kheswa,1, 4 I. K. B. Kullmann,5 M. Klintefjord,1 M. Markova,1 J. E. Midtbø,1 V. Modamio,1 W. Paulsen,1 L. G. Pedersen,1 T. Renstrøm,1 E. Sahin,1 S. Siem,1 G. M. Tveten,1 and M. Wiedeking6, 7 1Department of Physics, University of Oslo, N-0316 Oslo, Norway 2Department of Physics, Eskisehir Osmangazi University, Faculty of Science and Letters, TR-26040 Eskisehir, Turkey 3Department of Metallurgical and Materials Engineering, Pamukkale University, 20160 Denizli, Turkey 4Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa 5Institut d’Astronomie et d’Astrophysique, CP-226, Université Libre de Bruxelles, 1050 Brussels, Belgium 6SSC Laboratory, iThemba LABS, P.O. Box 722, Somerset West 7129, South Africa 7School of Physics, University of the Witwatersrand, Johannesburg 2050, South Africa (Dated: April 20, 2022)

We present the first experimental evidence of the scissors mode in the superheavy nucleus 254No produced in the 208Pb(48Ca, 2nγ))254No reaction. The spectrum of γ rays emitted by the excited 254No nuclei shows an enhanced γ-ray yield for transition energies of ≈2.5 MeV. By measuring the linear polarization properties of the emitted γ rays, we confirm that the transitions in the enhancement region are predominantly of magnetic-dipole character, characteristic for the scissors mode. To further characterize the enhanced γ-ray yield, simulations of the electromagnetic decay of 254No were performed. The observed enhancement is reproduced by including an M1 component in the γ strength function with total strength B(M1↑)=11.8(19)μN2. This is in good agreement with the integrated M1 strength from sum-rule estimates and new calculations within the quasi-particle random-phase approximation presented here. Our results provide a stringent test of phenomenological formulae for the scissors mode currently used in stellar nucleosynthesis calculations. We find that those formulae are not satisfactory, and we recommend using sum-rule estimates assuming a rigid-body moment of inertia instead for describing the scissors mode in superheavy nuclei.

The experimental gamma-ray strength functions (gamma-SFs) of 142,144-151Nd have been studied for gamma-ray energies up to the neutron separation energy. The results represent a unique set of gamma-SFs for an isotopic chain with increasing nuclear deformation. The data reveal how the low-energy enhancement, the scissors mode and the pygmy dipole resonance evolve with nuclear deformation and mass number. The data indicate that the mechanisms behind the low-energy enhancement and the scissors mode are decoupled from each other.

The Oslo method comprises a set of analysis techniques designed to extract nuclear level density and average gamma-decay strength function from a set of excitation-energy tagged gamma-ray spectra. Here we present a new software implementation of the entire Oslo method, called OMpy. We provide a summary of the theoretical basis and derive the essential equations used in the Oslo method. In addition to the functionality of the original analysis code, the new implementation includes novel components such as a rigorous method to propagate uncertainties throughout all steps of the Oslo method using a Monte Carlo approach. The resulting level density and gamma-ray strength function have to be normalized to auxiliary data. The normalization is performed simultaneously for both quantities, thus preserving all correlations. The software is verified by the analysis of a synthetic spectrum and compared to the results of the previous implementation, the oslo-method-software. Program summary Program Title: OMpy (Midtb empty set et al., 2020) CPC Library link to program files: https://doi.org/10.17632/jbthtbm9bd.1 Code Ocean Capsule: https://doi.org/10.24433/CO.6094094.v1 Licensing provisions: GPLv3 Programming language: Python, Cython Nature of problem: Extraction of the nuclear level density and average gamma-ray strength function from a set of excitation-energy tagged gamma-ray spectra including the quantification of uncertainties and correlations of the results. Solution method: The level density and gamma-ray strength function can be obtained simultaneously using a set of analysis techniques called the Oslo method. To propagate the uncertainty from the counting statistics, we analyze an ensemble of perturbed spectra, which are created based on the experimental input. One obtains a set of level densities and gamma-ray strength functions for each realization from a fit process. The fitting metric (chi(2)) is degenerate, but the degeneracy is removed by a simultaneous normalization of the level density and gamma-ray strength function to external data, such that all correlations are preserved. There have been several modifications to facilitate a modular program flow and to enhance accuracy, reproducibility and transparency of the results. The main revisions in OMpy are that it (i) uses an ensemble based uncertainty quantification throughout whole method, (ii) the fitting is based on well tested external libraries, (iii) corrections for the normalization procedure have been introduced, (iv) the code base is auto-documented with Sphinx and automatically tested. (C)2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Understanding the evolution of level densities in the crossover from spherical to well-deformed nuclei has been a long-standing problem in nuclear physics. We measure nuclear level densities for a chain of neodymium isotopes 142,144−151Nd which exhibit such a crossover. These results represent the most complete data set of nuclear level densities to date for an isotopic chain between neutron shell-closure and towards mid-shell. We observe a strong increase of the level densities along the chain with an overall increase by a factor of ≈150 at an excitation energy of 6 MeV and saturation around mass 150. Level densities calculated by the shell model Monte Carlo (SMMC) are in excellent agreement with these experimental results. Based on our experimental and theoretical findings, we offer an explanation of the observed mass dependence of the level densities in terms of the intrinsic single-particle level density and the collective enhancement.