We study 15 thermonuclear X-ray bursts from 4U 1820--30 observed with the Neutron Star Interior Composition Explorer (NICER). We find evidence of a narrow emission line at 1.0 keV and three absorption lines at 1.7, 3.0, and 3.75 keV, primarily around the photospheric radius expansion phase of most bursts. The 1.0 keV emission line remains constant, while the absorption features, attributed to wind-ejected species, are stable but show slight energy shifts, likely due to combined effects of Doppler and gravitational redshifts. We also examine with NICER the ``aftermath'' of a long X-ray burst (a candidate superburst observed by MAXI) on 2021 August 23 and 24. The aftermath emission recovers within half a day from a flux depression. During this recovery phase, we detect two emission lines at 0.7 and 1 keV, along with three absorption lines whose energies decreased to 1.57, 2.64, and 3.64 keV. Given the nature of the helium white-dwarf companion, these absorption lines during the aftermath may originate from an accretion flow, but only if the accretion environment is significantly contaminated by nuclear ashes from the superburst. This provides evidence of temporary metal enhancement i
The COVID-19 pandemic has permanently altered workplace structures, normalizing remote work. However, critical evidence highlights challenges with fully remote arrangements, particularly for software teams. This study investigates employee resignation patterns at Ericsson, a global developer of software-intensive systems, before, during, and after the pandemic. Using HR data from 2016-2025 in Ericsson Sweden, we analyze how different work modalities (onsite, remote, and hybrid) influence employee retention. Our findings show a marked increase in resignations from summer 2021 to summer 2023, especially among employees with less than five years of tenure. Employees onboarded remotely during the pandemic were significantly more likely to resign within their first three years, even after returning to the office. Exit surveys suggest that remote onboarding may fail to establish the necessary organizational attachment, the feeling of belonging and long-term retention. By contrast, the company's eventual successful return to pre-pandemic retention rates illustrates the value of differentiated work policies and supports reconsidering selective return-to-office (RTO) mandates. Our study dem
Context: Over the last decade, the forestry sector has undergone substantial changes, evolving from a post-2008 financial crisis landscape to incorporating policies favoring sustainable and green alternatives, especially after the 2015 Paris agreement. This evolution was drastically disrupted with the advent of the COVID-19 pandemic in 2020, causing unprecedented interruptions in supply chains, product markets, and data collection. Grasping the aftermath of the COVID-19, regional instances of the forest supply chain sector need synthetic pictures of their present state and future opportunities for emerging wood products and better regional-scale carbon balance. But given the impact of COVID-19 lock-down on data collection, the production of such synthetic pictures has become more complex, yet essential. This was the case for the regional supply chain of the Grand-Est region in France that we studied. Aims: For this study, our aim was to demonstrate that an integrated methodology could provide such synthetic picture even though we sued heterogenous sources of data and different analytical objectives: i.e. (1) retrospectively evaluate the aftermath of COVID-19 pandemic on the supply
This study investigates how well computational embeddings align with human semantic judgments in the processing of English compound words. We compare static word vectors (GloVe) and contextualized embeddings (BERT) against human ratings of lexeme meaning dominance (LMD) and semantic transparency (ST) drawn from a psycholinguistic dataset. Using measures of association strength (Edinburgh Associative Thesaurus), frequency (BNC), and predictability (LaDEC), we compute embedding-derived LMD and ST metrics and assess their relationships with human judgments via Spearmans correlation and regression analyses. Our results show that BERT embeddings better capture compositional semantics than GloVe, and that predictability ratings are strong predictors of semantic transparency in both human and model data. These findings advance computational psycholinguistics by clarifying the factors that drive compound word processing and offering insights into embedding-based semantic modeling.
The Northern European Enclosure Dam (NEED) is a hypothetical project to prevent flooding in European countries following the rising ocean level due to melting arctic glaciers. This project involves the construction of two large dams between Scotland and Norway, as well as England and France. The anticipated cost of this project is 250 to 500 billion euros. In this paper, we present the simulation of the aftermath of flooding on the European coastline caused by a catastrophic break of this hypothetical dam. From our simulation results, we can observe that there is a traveling wave after the accident, with a velocity of around 10 kilometers per hour, raising the sea level permanently inside the dammed region. This observation implies a need to construct additional dams or barriers protecting the northern coastline of the Netherlands and the interior of the Baltic Sea. Our simulations have been obtained using the following building blocks. First, a graph transformation model was applied to generate an adaptive mesh approximating the topography of the Earth. We employ the composition graph grammar model for breaking triangular elements in the mesh without the generation of hanging node
Colombia's prolonged conflict has made the country one of the most affected by forced internal displacement (FID) in the world. This study examines the impact of the FARC's 2014 unilateral and permanent ceasefire on FID. We use a difference-in-differences strategy that exploits the timing of the ceasefire and the pre-conflict distribution of FARC presence across municipalities. Results show a substantial reduction in severe displacement episodes in affected areas, with effects that emerged gradually and persisted over time. These findings highlight the importance of stability and the effective implementation of peace agreements in mitigating FID and its far-reaching consequences.
In this paper, we explore the aftermath of the Silicon Valley Bank (SVB) collapse, with a particular focus on its impact on crypto markets. We conduct a multi-dimensional investigation, which includes a factual summary, analysis of user sentiment, and examination of market performance. Based on such efforts, we uncover a somewhat counterintuitive finding: the SVB collapse did not lead to the destruction of cryptocurrencies; instead, they displayed resilience.
V5579 Sgr was a fast nova discovered in 2008 April 18.784 UT. We present the optical spectroscopic observations of the nova observed from the Castanet Tolosan, SMARTS and CTIO observatories spanning over 2008 April 23 to 2015 May 11. The spectra are dominated by hydrogen Balmer, Fe II and O I lines with P-Cygni profiles in the early phase, typical of an Fe II class nova. The spectra show He I and He II lines along with forbidden lines from N, Ar, S, and O in the nebular phase. The nova showed a pronounced dust formation episode that began about 20 days after the outburst. The dust temperature and mass were estimated using the WISE data from spectral energy distribution (SED) fits. The PAH-like features are also seen in the nova ejecta in the mid-IR Gemini spectra taken 522 d after the discovery. Analysis of the light curve indicates values of t$_2$ and t$_3$ about 9 and 13 days, respectively, placing the nova in the category of fast nova. The best fit cloudy model of the early decline phase JHK spectra obtained on 2008 May 3 and the nebular optical spectrum obtained on 2011 June 2 shows a hot white dwarf source with T$_{BB}$ $\sim$ 2.6 $\times$ 10$^5$ K having a luminosity of 9.8 $
Excess emission, associated with warm, dust belts, commonly known as exozodis, has been observed around a third of nearby stars. The high levels of dust required to explain the observations are not generally consistent with steady-state evolution. A common suggestion is that the dust results from the aftermath of a dynamical instability, an event akin to the Solar System's Late Heavy Bombardment. In this work, we use a database of N-body simulations to investigate the aftermath of dynamical instabilities between giant planets in systems with outer planetesimal belts. We find that, whilst there is a significant increase in the mass of material scattered into the inner regions of the planetary system following an instability, this is a short-lived effect. Using the maximum lifetime of this material, we determine that even if every star has a planetary system that goes unstable, there is a very low probability that we observe more than a maximum of 1% of sun-like stars in the aftermath of an instability, and that the fraction of planetary systems currently in the aftermath of an instability is more likely to be limited to <0.06. This probability increases marginally for younger or
We study percolation on the sites of a finite lattice visited by a generalized random walk of finite length with periodic boundary conditions. More precisely, consider Levy flights and walks with finite jumps of length $>1$ (like knight's move random walks (RW) in 2 dimensions and generalized knight's move RW in 3d). In these walks, the visited sites do not form (as in ordinary RW) a single connected cluster, and thus percolation on them is non-trivial. The model essentially mimics the spreading of an epidemic in a population weakened by the passage of some devastating agent -- like diseases in the wake of a passing army or of a hurricane. Using the density of visited sites (or the number of steps in the walk) as a control parameter, we find a true continuous percolation transition in all cases except for the 2-d knight's move RW and Levy flights with Levy parameter $σ\geq 2$. For 3-d generalized knight's move RW, the model is in the universality class of Pacman percolation, and all critical exponents seem to be simple rationals, in particular $β=1$. For 2-d Levy flights with $0 <σ< 2$, scale invariance is broken even at the critical point, which leads at least to very lar
On 15th September 2022, The Merge marked the Ethereum network's transition from computation-hardness-based consensus (proof-of-work) to a committee-based consensus mechanism (proof-of-stake). As a result, all the specialized hardware and GPUs that were being used by miners ceased to be profitable in the main Ethereum network. Miners were then left with the decision of how to re-purpose their hardware. One such choice was to try and make a profit mining another existing PoW system. In this study, we explore this choice by analyzing the hashrate increase in the top PoW networks following the merge. Our findings reveal that the peak increase in hashrate to other PoW networks following The Merge represents an adoption of at least 41% of the hashrate that was present in Ethereum, with 12% remaining more than 5 months later. Though we measure a drastic decrease in profitability by almost an order of magnitude, the continued presence of miners halts claims that power consumption was instantly addressed by Ethereum's switch to PoS.
Climate change poses new risks for real estate assets. Given that the majority of home buyers use a loan to pay for their homes and the majority of these loans are purchased by the Government Sponsored Enterprises (GSEs), it is important to understand how rising natural disaster risk affects the mortgage finance market. The climate securitization hypothesis (CSH) posits that, in the aftermath of natural disasters, lenders strategically react to the GSEs conforming loan securitization rules that create incentives that foster both moral hazard and adverse selection effects. The climate risks bundled into GSE mortgage-backed securities emerge because of the complex securitization chain that creates weak monitoring and screening incentives. We survey the recent theoretical literature and empirical literature exploring screening incentive effects. Using regression discontinuity methods, we test key hypotheses presented in the securitization literature with a focus on securitization dynamics immediately after major hurricanes. Our evidence supports the CSH. We address the data construction issues posed by LaCour-Little et. al. and show that their concerns do not affect our main results.
Context: Classical nova progenitors are cataclysmic variables and very old novae are observed to match high mass transfer rate and (relatively) long orbital period systems. However, the aftermath of a classical nova has never been studied in detail. Aims: To probe the aftermath of a classical nova explosion in cataclysmic variables and observe as the binary system relaxes to quiescence. Methods: We used multi-wavelength time resolved optical and near-infrared spectroscopy for a bright, well studied classical nova five years after outburst. We were able to disentangle the contribution of the ejecta at this late epoch using its previous characterization, separating the ejecta emission from that of the binary system. Results: We determined the binary orbital period (P=3.76 hr), the system separation and mass ratio (q>=0.17 for an assumed white dwarf mass of 1.2 solar masses). We find evidence of an irradiated secondary star and no unambiguous signature of an accretion disk, although we identify a second emission line source tied to the white dwarf with an impact point. The data are consistent with a bloated white dwarf envelope and the presence of unsettled gas within the white dwa
During the COVID-19 pandemic, the Church closed its physical doors for the first time in about 800 years, which is, arguably, a cataclysmic event. Other religions have found themselves in a similar situation, and they were practically forced to move online, which is an unprecedented occasion. In this paper, we analyse this sudden change in religious activities twofold: we create and deliver a questionnaire, as well as analyse Twitter data, to understand people's perceptions and activities related to religious activities online. Importantly, we also analyse the temporal variations in this process by analysing a period of 3 months: July-September 2020. Additionally to the separate analysis of the two data sources, we also discuss the implications from triangulating the results.
Short $γ$-ray burst (sGRB) jets form in the aftermath of a neutron star merger, drill through disk winds and dynamical ejecta, and extend over four to five orders of magnitude in distance before breaking out of the ejecta. We present the first 3D general-relativistic magnetohydrodynamic sGRB simulations to span this enormous scale separation. They feature three possible outcomes: jet+cocoon, cocoon, and neither. Typical sGRB jets break out of the dynamical ejecta if (i) the bound ejecta's isotropic equivalent mass along the pole at the time of the BH formation is $ \lesssim10^{-4}~{\rm M_{\odot}} $, setting a limit on the delay time between the merger and BH formation, otherwise, the jets perish inside the ejecta and leave the jet-inflated cocoon to power a low-luminosity sGRB; (ii) the post-merger remnant disk contains strong large-scale vertical magnetic field, $\gtrsim10^{15}$ G; and (iii) if the jets are weak ($\lesssim10^{50}$ erg), the ejecta's isotropic equivalent mass along the pole must be small ($\lesssim10^{-2}~{\rm M_{\odot}}$). Generally, the jet structure is shaped by the early interaction with disk winds rather than the dynamical ejecta. As long as our jets break out
Simulations of the moon-forming impact suggest that most of the lunar material derives from the impactor rather than the Earth. Measurements of lunar samples, however, reveal an oxygen isotope composition that is indistinguishable from terrestrial samples, and clearly distinct from meteorites coming from Mars and Vesta. Here we explore the possibility that the silicate Earth and impactor were compositionally distinct with respect to oxygen isotopes, and that the terrestrial magma ocean and lunar-forming material underwent turbulent mixing and equilibration in the energetic aftermath of the giant impact. This mixing may arise in the molten disk epoch between the impact and lunar accretion, lasting perhaps 10^2-10^3 yr. The implications of this idea for the geochemistry of the Moon, the origin of water on Earth, and constraints on the giant impact are discussed.
Forty-five years ago, a young researcher in finite permutation group theory encountered a paper by Robert Woodrow. The homogeneous triangle-free graph Woodrow described there seemed to be an infinite analogue of the Higman--Sims graph which had played an important role in the researcher's thesis. The encounter changed the course of the researcher's career. This paper is the story of that event and its aftermath. The final section of the paper suggests that Fraïssé classes of rigid structures are a potentially interesting generalisation of Ramsey classes.
In the last decade, the ringdown community has made large strides in understanding the aftermath of binary black hole mergers through the study of numerical simulations. In this note, we introduce two flavors of fitting algorithms, that have been verified against each other, for the extraction of quasinormal mode amplitudes from ringdown waveforms - $\texttt{qnmfits}$ in Python and $\texttt{KerrRingdown}$ in Mathematica.
In the aftermath of earthquakes, social media images have become a crucial resource for disaster reconnaissance, providing immediate insights into the extent of damage. Traditional approaches to damage severity assessment in post-earthquake social media images often rely on classification methods, which are inherently subjective and incapable of accounting for the varying extents of damage within an image. Addressing these limitations, this study proposes a novel approach by framing damage severity assessment as a semantic segmentation problem, aiming for a more objective analysis of damage in earthquake-affected areas. The methodology involves the construction of a segmented damage severity dataset, categorizing damage into three degrees: undamaged structures, damaged structures, and debris. Utilizing this dataset, the study fine-tunes a SegFormer model to generate damage severity segmentations for post-earthquake social media images. Furthermore, a new damage severity scoring system is introduced, quantifying damage by considering the varying degrees of damage across different areas within images, adjusted for depth estimation. The application of this approach allows for the quan
This study presents a framework for assessing urban critical infrastructure resilience during extreme events, such as hurricanes. The approach combines GIS and network analysis with open remote sensing data of the aftermath, vector data on infrastructure, and socio-demographic attributes of populations in affected areas. Using Panama City as an example case study, this paper quantifies hurricane impacts on residents and identifies vulnerable locations for urban planners' attention. Simulations demonstrate how implementing measures at identified weak points can improve system resilience. Comparing pre-hurricane conditions with the aftermath and several years later allows observing network property changes and assessing overall resilience improvements. Findings indicate that individuals over 65 in the studied settlement are more susceptible to disasters, while males in this age category face higher risks.