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Dynamic programming (DP) is a sub-field of optimization concerned with sequential decision making over time. The essential ideas of DP have been adopted in many applications, from robotics and AI to the sequencing of DNA. It is used around the world to control aircraft, route shipping, test products, recommend information on media platforms and solve major research problems. Dynamic Programming: Finite States treats the theory of dynamic programming and its applications in economics, finance, and operations research. It contains classical results on dynamic programming as well as extensions created by researchers and practitioners as they wrestle with formulating and solving dynamic models that can explain patterns observed in data. Adopting an abstract framework that provides great generality, this book facilitates rapid progress to the research frontier by combining rigorous theory with numerous applications, many solved exercises, and detailed open-source computer code.
Recent changes to US research funding are having far-reaching consequences that imperil the integrity of science and the provision of care to vulnerable populations. Resisting these changes, the BJPsych Portfolio reaffirms its commitment to publishing mental science and advancing psychiatric knowledge that improves the mental health of one and all.
The stars of the Milky Way carry the chemical history of our Galaxy in their atmospheres as they journey through its vast expanse. Like barcodes, we can extract the chemical fingerprints of stars from high-resolution spectroscopy. The fourth data release (DR4) of the Galactic Archaeology with HERMES (GALAH) Survey, based on a decade of observations, provides the chemical abundances of up to 32 elements for 917 588 stars that also have exquisite astrometric data from the Gaia satellite. For the first time, these elements include life-essential nitrogen to complement carbon, and oxygen as well as more measurements of rare-earth elements critical to modern-life electronics, offering unparalleled insights into the chemical composition of the Milky Way. For this release, we use neural networks to simultaneously fit stellar parameters and abundances across the whole wavelength range, leveraging synthetic grids computed with Spectroscopy Made Easy. These grids account for atomic line formation in non-local thermodynamic equilibrium for 14 elements. In a two-iteration process, we first fit stellar labels to all 1 085 520 spectra, then co-add repeated observations and refine these labels using astrometric data from Gaia and 2MASS photometry, improving the accuracy and precision of stellar parameters and abundances. Our validation thoroughly assesses the reliability of spectroscopic measurements and highlights key caveats. GALAH DR4 represents yet another milestone in Galactic archaeology, combining detailed chemical compositions from multiple nucleosynthetic channels with kinematic information and age estimates. The resulting dataset, covering nearly a million stars, opens new avenues for understanding not only the chemical and dynamical history of the Milky Way but also the broader questions of the origin of elements and the evolution of planets, stars, and galaxies.
An important component of post-release monitoring of biological control of invasive plants is the tracking of species interactions. During post-release monitoring following the initial releases of the weevil Ceutorhynchus scrobicollis Nerenscheimer and Wagner (Coleoptera: Curculionidae) on garlic mustard, Alliaria petiolata (Marschall von Bieberstein) Cavara and Grande (Brassicaceae), in Ontario, Canada, we identified the presence of larvae of the tumbling flower beetle, Mordellina ancilla Leconte (Coleoptera: Mordellidae), in garlic mustard stems. This study documents the life history of M. ancilla on garlic mustard to assess for potential interactions between M. ancilla and C. scrobicollis as a biological control agent. Garlic mustard stems were sampled at eight sites across southern Ontario and throughout the course of one year to record the prevalence of this association and to observe its life cycle on the plant. We found M. ancilla to be a widespread stem-borer of late second–year and dead garlic mustard plants across sampling locations. This is the first host record for M. ancilla on garlic mustard. The observed life cycle of M. ancilla indicates that it is unlikely to negatively impact the growth and reproduction of garlic mustard and that it is unlikely to affect the use of C. scrobicollis as a biological control agent.
Following democracy’s global advance in the late twentieth century, recent patterns of democratic “backsliding” have generated extensive scholarly debate. Since backsliding towards autocracy is often the work of elected leaders operating within democratic institutions, it challenges conventional thinking about democratic consolidation, the enforcement of institutional checks and balances, and the reproduction of democratic norms. Drawing insights from classic literature on democratic transitions and consolidation, this volume examines the nature of contemporary threats to democracy, recognizing that the central challenge is not always to induce the compliance of those who lose elections, but rather those who emerge victorious and turn the institutional leverage of incumbency into a source of ongoing competitive advantage. There is, then, both a “loser’s dilemma” and a “winner’s dilemma” embedded in the study of democratic resiliency. Patterns of backsliding have revealed the contingent and potentially contested underpinnings of democratic institutions in any political order, given the presence (whether latent or active) of authoritarian political and cultural currents. Democracy is, therefore, best understood not as a standardized regime template or a static endpoint of political development, but rather as a dialectical frontier that advances ‒ and sometimes recedes ‒ according to the dynamic interplay countervailing forces.
As explained in Chapter 1, state institutions are inevitably transformed into sites of regime contestation between democratic and autocratic forces when democratic backsliding is threatened or underway. That is especially the case in social and political contexts where exclusionary forms of majoritarian rule or ethnonationalism contest liberal and pluralist civil societies. The challenge for scholars is to identify the conditions under which key institutional sites serve as bastions of democratic accountability and resilience, and how and when these sites can be neutralized or even transformed into weapons of autocratization. Often referred to as “referee institutions” (such as constitutional courts and electoral commissions) and tools of horizontal accountability for checking executive aggrandizement (including ombudsman, investigative bureaus, and information commissions), key state agencies must be sufficiently capacious and nonpartisan to serve as guardrails in times of democratic contestation and regime uncertainty.
It remains unclear which individuals with subthreshold depression benefit most from psychological intervention, and what long-term effects this has on symptom deterioration, response and remission.
Aims
To synthesise psychological intervention benefits in adults with subthreshold depression up to 2 years, and explore participant-level effect-modifiers.
Method
Randomised trials comparing psychological intervention with inactive control were identified via systematic search. Authors were contacted to obtain individual participant data (IPD), analysed using Bayesian one-stage meta-analysis. Treatment–covariate interactions were added to examine moderators. Hierarchical-additive models were used to explore treatment benefits conditional on baseline Patient Health Questionnaire 9 (PHQ-9) values.
Results
IPD of 10 671 individuals (50 studies) could be included. We found significant effects on depressive symptom severity up to 12 months (standardised mean-difference [s.m.d.] = −0.48 to −0.27). Effects could not be ascertained up to 24 months (s.m.d. = −0.18). Similar findings emerged for 50% symptom reduction (relative risk = 1.27–2.79), reliable improvement (relative risk = 1.38–3.17), deterioration (relative risk = 0.67–0.54) and close-to-symptom-free status (relative risk = 1.41–2.80). Among participant-level moderators, only initial depression and anxiety severity were highly credible (P > 0.99). Predicted treatment benefits decreased with lower symptom severity but remained minimally important even for very mild symptoms (s.m.d. = −0.33 for PHQ-9 = 5).
Conclusions
Psychological intervention reduces the symptom burden in individuals with subthreshold depression up to 1 year, and protects against symptom deterioration. Benefits up to 2 years are less certain. We find strong support for intervention in subthreshold depression, particularly with PHQ-9 scores ≥ 10. For very mild symptoms, scalable treatments could be an attractive option.
The hitherto oldest known mass mortality of clam shrimp is described from the Early Devonian (Emsian) of Luxembourg. This (almost) monospecific clam shrimp association allows for a much more comprehensive assessment and understanding of preservational and ontogenetic variation in a single taxon, Pseudestheria diensti (Gross, 1934). This suggests that other taxa originally described from the “classical” Willwerath locality, the type locality of P. diensti, are variants of the latter, and thus Pseudestheria subcircularis Raymond, 1946 and Palaeolimnadiopsis ? eifelensis Raymond, 1946 are synonymized here with P. diensti. A further clam shrimp taxon, for which we propose a new species, Palaeolimnadia stevenbeckeri n. sp., is found in the same stratum, but not in the mass mortality layer itself. The clam shrimp mass mortality is interpreted to reflect sudden destruction of the original habitat on a delta plain and subsequent transport and burial in a marginal marine low-energy setting.
Large-eddy simulation (LES) is performed to study the tip vortex flow in a ducted propulsor geometry replicating the experiments of Chesnakas & Jessup (2003, pp. 257–267), Oweis et al. (2006a J. Fluids Engng128, 751–764) and Oweis et al. (2006b J. Fluids Engng128, 751–764). Inception of cavitation in these marine propulsion systems is closely tied to the unsteady interactions between multiple vortices in the tip region. Here LES is used to shed insight into the structure of the tip vortex flow. Simulation results are able to predict experimental propeller loads and show agreement with laser Doppler velocimetry measurements in the blade wake at design advance ratio, $J=0.98$. Results show the pressure differential across the blade produces a leakage vortex which separates off the suction side blade tip upstream of the trailing edge. The separation sheet aft of the primary vortex separation point is shown to take the form of a skewed shear layer which produces a complex arrangement of unsteady vortices corotating and counter-rotating with the primary vortex. Blade tip boundary layer vortices are reoriented to align with the leakage flow and produce instantaneous low-pressure regions wrapping helically around the primary vortex core. Such low-pressure regions are seen both upstream and downstream of the propeller blade trailing edge. The trailing edge wake is found to only rarely have a low-pressure vortex core. Statistics of instantaneous low pressures below the minimum mean pressure are found to be concentrated downstream of the blade’s trailing edge wake crossing over the primary vortex core and continue in excess of 40 % chord length behind the trailing edge. The rollup of the leakage flow duct boundary layer behind the trailing edge is also seen to produce counter-rotating vortices which interact with the primary leakage vortex and contribute to strong stretching events.
Thermo-responsive hydrogels are smart materials that rapidly switch between hydrophilic (swollen) and hydrophobic (shrunken) states when heated past a threshold temperature, resulting in order-of-magnitude changes in gel volume. Modelling the dynamics of this switch is notoriously difficult and typically involves fitting a large number of microscopic material parameters to experimental data. In this paper, we present and validate an intuitive, macroscopic description of responsive gel dynamics and use it to explore the shrinking, swelling and pumping of responsive hydrogel displacement pumps for microfluidic devices. We finish with a discussion on how such tubular structures may be used to speed up the response times of larger hydrogel smart actuators and unlock new possibilities for dynamic shape change.