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We live in a time of significant global risk. Some research has focused on understanding systemic sources of this risk, while other research has focused on possible worst-case outcomes. In this article, we bring together these two areas of research and provide a simple conceptual framework that shows how emergent features of the global system contribute to the risk of global catastrophe.
Technical summary
Humanity faces a complex and dangerous global risk landscape, and many different terms and concepts have been used to make sense of it. One broad strand of research characterises how risk emerges within the complex global system, using concepts like systemic risk, Anthropocene risk, synchronous failure, negative social tipping points, and polycrisis. Another focuses on possible worst-case outcomes, using concepts like global catastrophic risk (GCR), existential risk, and extinction risk. Despite their clear relevance to each other, connections between these two strands remain limited. Here, we provide a simple conceptual framework that synthesises these research strands and shows how emergent properties of the global system contribute to the risk of global catastrophic outcomes. In particular, we show that much of GCR stems from the interaction of hazards and vulnerabilities that arise endogenously within the global system, and how ‘systems thinking’ and complex adaptive systems theory can help illuminate this. We also highlight some unique challenges that systemic sources of GCR pose for risk assessment and mitigation, discuss insights for policy, and outline potential paths forward.
Social media summary
The global system is generating global catastrophic risk.
This study examined the variability of language profiles in Spanish–English bilingual children with and without developmental language disorder (DLD). The data included 529 children between the ages of 5 and 10 years. Eighty-eight of these children were identified as having DLD. A latent profile analysis was conducted based on children’s morphosyntax and semantics performance in Spanish and English. The optimal model identified five different profiles, illustrating the heterogeneity in bilingual development. Children with DLD were observed across all profiles, but most were classified in the only two profiles where lower morphosyntax than semantic performance was observed across languages. These results show the variability in both bilingual children with and without DLD. Additionally, the hallmark deficit of DLD in morphosyntax was confirmed, with the morphological weakness being observed in each of the bilingual children’s languages. Children’s background factors (age, maternal education and language exposure) were associated with profile characteristics.
To assess whether antibiotic duration (AD) and one-year antibiotic-free days (AFD) are associated with key in-hospital and post-discharge outcomes among critically ill adults.
Design:
Prospective observational study.
Setting:
611-bed, quaternary care academic medical center in the United States.
Patients:
126 critically ill adults (mean age 68.1 ± 15.6 yr, 51.6% male, median APACHE II score 20.5 [IQR 15–25]); 71.4% met sepsis criteria.
Methods:
Secondary infection was defined as ≥3 consecutive antibiotic days within a year after the index sepsis admission. Multivariate analyses adjusted for age, APACHE II score, BMI, and glucocorticosteroid dose. Time-to-event analysis employed Cox proportional hazards modeling; cumulative infection burden was assessed via nonparametric tests using normalized antibiotic exposure (AD as a proportion of days alive).
Results:
Within 30 days, longer AD correlated with increased hospital stay; each additional antibiotic day added ∼0.93 hospital days (P < 0.001) in adjusted linear regression. AD did not predict one-year mortality (OR 1.01, P = 0.739) or readmission (OR 1.01, P = 0.771). Normalized antibiotic exposure significantly differed by cumulative secondary infection episodes (P = 0.0033), with higher exposure among patients experiencing two or more secondary infections (P = 0.026 and P = 0.036, respectively). Cox regression showed a significant association between AD and time to first secondary infection (HR 1.10, 95% CI: 1.04–1.15, P = 0.001), indicating that longer AD predisposed to secondary infection or recurrent antibiotic use.
Conclusions:
Extended AD, in critically ill patients, prolongs hospitalization without reducing mortality or readmission rates. These findings highlight the importance of robust antibiotic stewardship practices, where shorter, targeted regimens may minimize unintended complications.
This article analyzes structures of feeling among the generation of trauma carriers who grew up under Pinochet’s dictatorship. Drawing on interviews with thirty-seven cultural producers (including filmmakers, novelists, visual artists, and memory activists), we shed light on the generational memory work involved in processing cultural trauma, emphasizing the emotional force behind memory transmission in postconflict societies dealing with legacies of terror. Drawing on Raymond Williams’s notion of structures of feeling, we explore how the generational memory of children during Pinochet’s dictatorship is shaped by melancholic intergenerational identification with past struggles. This intergenerational bond is characterized by melancholic affect in representing the previous generation, which is rooted in experiences of state violence and resistance and plays a key role in processing historical trauma and shaping contemporary social critique in postconflict Chile.
This paper presents a novel machine learning framework for reconstructing low-order gust-encounter flow field and lift coefficients from sparse, noisy surface pressure measurements. Our study thoroughly investigates the time-varying response of sensors to gust–airfoil interactions, uncovering valuable insights into optimal sensor placement. To address uncertainties in deep learning predictions, we implement probabilistic regression strategies to model both epistemic and aleatoric uncertainties. Epistemic uncertainty, reflecting the model’s confidence in its predictions, is modelled using Monte Carlo dropout – as an approximation to the variational inference in the Bayesian framework – treating the neural network as a stochastic entity. On the other hand, aleatoric uncertainty, arising from noisy input measurements, is captured via learned statistical parameters, and propagate measurement noise through the network into the final predictions. Our results showcase the efficacy of this dual uncertainty quantification strategy in accurately predicting aerodynamic behaviour under extreme conditions while maintaining computational efficiency, underscoring its potential to improve online sensor-based flow estimation in real-world applications.
Study coding is an essential component of the research synthesis process. Data extracted during study coding serve as a direct link between the included studies and the synthesis results, allowing reviewers to justify claims about the findings from a set of related studies. The purpose of this tutorial is to provide authors, particularly those new to research synthesis, with recommendations to develop study coding manuals and forms that result in efficient, high-quality data extraction. Each of the 10 easy-to-follow practices is supported with additional resources, examples, or non-examples to help authors develop high-quality study coding materials. With the increase in publication of meta-analyses in recent years across many disciplines, a primary goal of this article is to enhance the quality of study coding materials that authors develop.
Ultraintense laser–plasma experiments generate a variety of high-energy radiations, including nonlinear inverse Compton scattered (NCS) X-rays, which are expected to be a key experimental observable as we transition into the quantum electrodynamic plasma regime. However, there is also a high bremsstrahlung X-ray background that reduces our ability to observe NCS X-rays. Previous numerical studies comparing NCS and bremsstrahlung emissions fail to capture the full temporal emission of both processes. We present for the first time two-dimensional particle-in-cell (PIC) and three-dimensional hybrid-PIC EPOCH simulations that capture up to 150 ps of the laser–plasma interaction and directly compare the NCS and bremsstrahlung emissions for a plastic target for intensities of ${10}^{20}{-}{10}^{23}$ W/cm2. We present angular distribution plots where the NCS emission is seen to dominate at intensities greater than 5$\times {10}^{21}$ W/cm2 and the target design is seen to successfully divert the bremsstrahlung signal away from the NCS lobe regions, making the experimental observation of nonlinear inverse Compton scattering at lower intensities more likely.
Nonnative earthworm species are invading the boreal forest in North America. Oribatid mites are key detritivores in boreal forest soils, initiating litter decomposition and maintaining forest floor structure. Earthworms are also detritivores and are considered ecosystem engineers. When introduced into nonendemic environments, earthworms may alter soil biogeochemical cycling and adversely affect oribatid mite communities. However, to our knowledge, no field studies in boreal forests have investigated invasive earthworms and their impacts on oribatid mites. The present study was conducted in a boreal trembling aspen, Populus tremuloides Michaux (Salicaceae), stand near Wolf Lake, Alberta, Canada. After assessing the current state of earthworm invasion, we identified an area with a lower density of earthworms that was invaded by one species, Dendrobaena octaedra Savigny (Crassiclitellata: Lumbricidae), and an area with a higher density of earthworms that was invaded by multiple species, D. octaedra (Crassiclitellata: Lumbricidae) and Aporrectodea spp. (Crassiclitellata: Lumbricidae). The higher-density area was associated with lower understorey vegetation species richness and with thinner forest floors characterised by higher bulk density but lower total organic carbon and nitrogen stocks. Oribatid mite community composition differed between the two areas, and their richness significantly decreased with higher earthworm density. Our findings suggest that earthworm invasion is substantially disrupting habitat for oribatid mites and might affect the overall boreal ecosystem equilibrium in the long term.
We examine the convergence of lean hog futures and cash prices, focusing on the thinning of negotiated cash markets. Using daily Livestock Mandatory Reporting data from 2001 to 2024, we confirm significant non-convergence between negotiated and futures prices over the past two decades. Regression results show that as the share of negotiated transactions declines, the absolute basis increases, emphasizing the critical role of negotiated markets in ensuring convergence. These findings highlight concerns about the reliability of negotiated prices as a benchmark for contracts and offer valuable insights for price risk management in the hog industry.
We show that the Hausdorff dimension of the attractor of an inhomogeneous self-similar iterated function system (or self-similar IFS) can be well approximated by the Hausdorff dimension of the attractor of another inhomogeneous self-similar IFS satisfying the strong separation condition. We also determine a formula for the Hausdorff dimension of the algebraic product and sum of the inhomogeneous attractor.
The antibiotic spectrum index (ASI) outcome quantifies antibiotic exposure based on spectrum of activity. Our objective was to examine ASI as an exploratory outcome in the context of a recent stewardship-focused, clinical trial in childhood pneumonia that originally used a binary guideline-concordant outcome.
Design:
Secondary analysis of a randomized clinical trial.
Setting:
Two tertiary pediatric hospitals.
Methods:
Encounters were randomly assigned to clinical decision support (CDS) or usual care treatment arm. The ASI was calculated by summing daily ASI scores for each unique antibiotic administered. It was evaluated as a continuous and ordinal measure: No Antibiotics (ASI = 0), Narrow (1-2), Intermediate (3-4), Broad (5-7), and Very Broad (≥8). Proportional odds regression modeled the ordinal ASI outcome in the first 24 hours by treatment arm and compared to the guideline-concordance outcome. Results were stratified by emergency department (ED) disposition. We also conducted a longitudinal, descriptive analysis of day-to-day ASI for those with in-hospital dispositions.
Results:
We included 1027 encounters, 549 (53%) were randomized to CDS and 478 (47%) usual care respectively. ASI Category did not differ by treatment arm overall (Odds Ratio: 0.88[95% Confidence Interval: 0.70,1.09]), which mirrored binary guideline-concordance. Mean ASI was lower for concordant encounters (2.1 vs 8.4, P < 0.001) and across all ED dispositions. In the longitudinal analysis, there were 1137 day-to-day ASI comparisons, with only 7% representing spectrum escalations.
Conclusions:
The ASI outcome yielded similar results to a dichotomous concordance outcome. However, ASI provided more granular insights into antibiotic prescribing, suggesting ASI may be a useful outcome measure in future stewardship-focused trials.
A wideband harmonic rejection (HR) voltage-domain mixer using resistive scaling is presented featuring excellent linearity and high intermediate frequency (IF) bandwidth. Thin-oxide devices with constant gate-to-source voltages (VGS) are utilized to maximize the switching linearity. A novel switching core topology providing low-impedance IF outputs is proposed to support wideband in-phase (I) and quadrature (Q) mixer outputs when capacitively loaded by an analog-to-digital converter (ADC). Eight LO clock phases, each with a 25% duty cycle, are on-chip generated for quadrature down-conversion and HR. By cleverly activating and organizing the mixer branches, the mixer's input impedance at radio frequency (RF) can be kept perfectly constant throughout all eight clock phases, enhancing the mixer’s linearity. The TSMC 40 nm-CMOS realized mixer reaches 20.9 dBm OIP3 at an IF of 50 MHz with a conversion loss of 22.5 dB. It offers an 800 MHz 3-dB IF bandwidth when connected to a differential capacitive loading of 0.15 pF, with a total power consumption of 40.7 mW drawn from a 1.1 V supply. The mixer targets linear wideband base station observation receiver applications.
In this article, I present a modified reliabilist theory of knowledge which purports to solve many of the problems currently facing standard reliabilism. With the help of a dispositionally construed reliabilist theory of knowledge and justification (DRK and DRJ), tentative responses to the following problems for reliabilism are offered: The New Evil Demon Problem, The Clairvoyance Problem, The Mr. Truetemp Problem, The Gettier Problem, Barn Cases (Brandom’s and Goldman’s), and The Lottery Problem. Lastly, I argue that, despite diverging from the letter of standard reliabilism, DRK and DRJ remain within the spirit of reliabilist epistemology
Academic freedom is founded on two fundamental principles: professional autonomy and the public good. These dual foundations are necessarily in tension with each other. Academic freedom is not a civil right, as is freedom of speech, nor is it an individual employment benefit provided to those in a restricted number of academic appointments. It is, instead, a freedom belonging to the academic profession collectively to pursue inquiry and teach freely, limited and guided by the principles of that profession and of a scholar’s respective disciplines. Academic freedom guarantees both faculty members and students the right to engage in intellectual inquiry and debate without fear of censorship or retaliation. It grants considerable scope to the consciences of individual teachers and researchers, but functions ultimately as the collective freedom of the scholarly community to govern itself in the interest of serving the common good in a democratic society. Academic freedom must protect not only independent research and classroom teaching, but a scholar’s expression as a citizen of both the university and the broader polity. Hence, to thrive, academic freedom depends on a democratic and constitutional system that guarantees the rule of law. Academic freedom has always been contested and vulnerable, to be sure, but in recent years it has faced a series of escalating challenges almost everywhere, amounting to a major crisis. In this context, calls for ‘institutional neutrality’ must be critically examined.
We explored the dynamics of Taylor–Couette flows within square enclosures, focusing primarily on the turbulence regime and vortex behaviour at varying Reynolds numbers. Laboratory experiments were conducted using particle image velocimetry for Reynolds numbers $Re_{\varDelta }\in [0.23, 4.6]\times 10^3$ based on the minimum gap $\varDelta /d = 1/16$, $1/8$ and $1/4$, where $d$ is the cylinder diameter, or $Re\in [1.8, 9.8]\times 10^3$ based on $d/2$. At lower $Re$, the flow was dominated by well-defined Taylor and Görtler vortices, while higher $Re$ led to a turbulent state with distinct motions. Space–time radial velocity analysis revealed persistent Taylor vortices at lower $Re$, with larger gaps but increased turbulence, and irregular motions at higher $Re$, with smaller gaps. Velocity spectra reveal that the energy distribution is maintained at frequencies lower than the integral-type frequency $f_I$ across varying $\varDelta$ due to the dominance of large vortices. However, there is a monotonic increase in energy at higher frequencies beyond $f_I$. The reduced characteristic frequency $f_I\varDelta /\omega _ir_i \sim 1/10$ indicates that these motions scale linearly with angular velocity, and inversely with the gap. Proper orthogonal decomposition (POD) and spectral POD were used to distinguish between Taylor and Görtler vortices, showing the effects of gap size and the associated energy cascade. Linear stability analysis included as complementary support revealed primary instability of the Taylor vortex, which is similar to the circular enclosure, along with multiple corner modes that are unique to the geometry.
In the late 1740s and the 1750s the Jacobite exile James Steuart began to compose the work that became his Principles of Political Oeconomy. This article shows how the political principles of this work were shaped in two contexts neglected by earlier scholars: the networks that shaped Steuart’s formation as a Jacobite, and the debates about absolute monarchy that he encountered in France early during his exile starting in 1746. It demonstrates that Steuart’s vision of an economically active, interventionist state chiefly developed not from German debates about administration, as is often assumed, but from long-running Scottish currents of opposition to British government policy and radical French ideas about how monarchical reform can secure equal rights for all. This article thus uncovers the Jacobite and French origins of Steuart’s variety of interventionism, which troubled Adam Smith, inspired French revolutionaries, and influenced Hegel, Marx, and the broader history of political economy.
The fiduciary conception of political power that the republican tradition adopted in its struggle against absolutism was dissolving during the late eighteenth century and the nineteenth. However, in the mid-nineteenth century, some attempts appeared that represent a reemergence of the fiduciary democratic (or proto-democratic) scheme. One of them was the case of Spanish federalism and its greatest exponent, Francisco Pi y Margall. This article shows that the core of Pimargalian federal republican thought is based on a fiduciary conception of sovereignty, which is grounded in a recovery of the language of revolutionary natural law. By arguing that the fiduciary principle applied not only to his concept of public authority, but also to his comprehensive proposal for the federal reorganization of the state, this article contributes to a better understanding of the specific contribution of Pi’s work and to contemporary discussions on the foundations and scope of republicanism, federalism, and fiduciary relationships.
This study explores early domestic life at the historic Yoruba site of Orile-Owu. Excavations and ethnography reveal insights into diet and food processing, medicinal practices and the daily routines of occupants during the mid-fifteenth to mid-seventeenth centuries AD.