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Portfolio Selection in Contests
No full textIn an investment contest with incomplete information, a finite number of agents dynamically trade assets with idiosyncratic risk and are rewarded based on the relative ranking of their terminal portfolio values. We explicitly characterize a symmetric Nash equilibrium of the contest and rigorously verify its uniqueness. The connection between the reward structure and the agents’ portfolio strategies is examined. A top-heavy payout rule results in an equilibrium portfolio return distribution with high positive skewness, which suffers from a large likelihood of poor performance. Risky asset holding increases when competition intensifies in a winner-takes-all contest
Application of Raman spectroscopy and micro-indentation to micro-map the path and boundary of NaOCl-induced dentine collagen changes in an ex-vivo root canal irrigation model
No full textQuantifying volcanism during Oceanic Anoxic Event 2 constrained by sedimentary mercury
No full textThe Cretaceous Oceanic Anoxic Event 2 (OAE 2, ca. 94 Ma) is one of the most significant carbon cycle perturbations during the Mesozoic Era. It is widely considered to have been triggered by large igneous provinces (LIPs) volcanism. However, quantifying the pattern and magnitude of LIPs volcanic activity remain insufficiently understood. Here, we model sedimentary mercury enrichment and mercury isotope variations across OAE 2 to quantitatively evaluate the LIPs volcanism. Our global oceanic Hg box modeling results suggest an 8–16-fold increase (∼2480–4960 Mg yr−1) in volcanic Hg inputs to the atmosphere and ocean in the lead-up to the OAE onset. The global Hg enrichment factor (Hg-EF) data exhibit spatial heterogeneity during OAE 2. The lack of globally uniform Hg enrichment underscores the complex interplay between volcanism style (submarine vs. subaerial), paleogeographic isolation, and proximity to LIPs during OAE 2
Optimal Cutoffs for the Ratio of Arterial Oxygen Partial Pressure to Inspired Oxygen Fraction in Categorizing Respiratory Impairment Severity in Organ Failure Scores
No full textBackground:
The ratio of arterial oxygen partial pressure to fraction of inspired oxygen (PaO2/FiO2, hereafter P/F ratio) is a key component of the Sequential Organ Failure Assessment (SOFA) score. It reflects the severity of hypoxaemic respiratory failure. The ongoing revision of the SOFA score requires data-driven cutoffs for P/F ratio as well as rational criteria for respiratory support. In this study, we aimed to determine the optimal P/F ratio cutoffs for determining respiratory failure categories in the revised SOFA score and examined whether advanced respiratory support should be a prerequisite for the most severe categories.
Methods:
We used the database of the intensive care unit of Kuopio University Hospital, Finland, for cutoff derivation and the eICU database, a multicenter U.S. intensive care registry, for external validation. We identified cutoffs most discriminative for hospital mortality using the log-rank statistic test with the Contal and O'Quigley method. In external validation, these cutoffs were compared with those in the current respiratory SOFA score.
Results:
Optimal cutoffs were identified as follows: P/F ratio > 40 kPa (normal), 30–40 kPa (mild impairment), 20–30 kPa (moderate impairment), 10–20 kPa (severe impairment), and ≤ 10 kPa (critical impairment). These cutoffs resulted in clear separation of the severity categories (chi-square for log-rank statistic 356.9). They outperformed the current respiratory SOFA score cutoffs in the validation cohort (AUROC 0.615, 95% CI 0.607–0.622 vs. AUROC 0.610, 95% CI 0.603–0.618, p < 0.001). Advanced respiratory support was associated with higher mortality, but its inclusion as a prerequisite improved discrimination only in the moderately impaired respiratory function category, not in the severely or critically impaired categories.
Conclusion:
P/F ratio cutoffs using 10 kPa (75 mmHg) intervals were identified to be optimal for distinguishing stages of respiratory failure severity. The impact of respiratory support on P/F ratio–mortality associations suggests the need to calibrate any P/F ratio-based score by support level, but optimal calibration methods require further study
Biofilm removal in hospital sink drains drives unintended surges in antibiotic resistance
No full textLearning in the Limit: Income Inference from Credit Extensions
No full textCombining a randomized controlled trial with administrative and survey data, this paper shows that
credit limit extensions significantly increase total spending and income expectations. By
controlling for changes in personal income expectations, the spending response to credit-limit
extensions weakens by approximately 30%. For financially unconstrained consumers, expectation
changes account for around two-thirds of the spending responses to limit extensions. These findings
are consistent with consumers inferring future income from credit supply
The Obligations of Providers of General-Purpose AI Models
No full textDuring the legislative process, the EU Artificial Intelligence (AI) Act was amended to include provisions related to general-purpose AI (GPAI) models. These broadly relate to transparency towards downstream users and relevant regulators, in addition to obligations connected to intellectual property. In this paper, we provide detailed analysis of these new provisions in the context of current technological applications and emerging trajectories, connecting them to computing literature and practice, and the broader context of connected and adjacent legal regimes, in particular copyright and relevant emerging case law. We find that there are a significant number of inclarities, tensions and contradictions both within the text, between the text and other legal regimes, and between the text and guideline documents, such as the Code of Practice on General-Purpose AI and recent guidelines by the European Commission. We identify a range of issues with the scoping of the provisions which may undermine its policy goals and create loopholes for regulatory avoidance, such as those relating to non-commercial models, open-source models, and model finetuning along the value chain. We find that the Code of Practice contains significant omissions and misstatements, some of which may present a compliance risk for an entity choosing to rely on the Code. We do not consider the provisions on GPAI models which present a systemic risk, which are dealt with elsewhere in the volume which this work will form a part of
Shape vs Flow: A 2D Statistical Shape Analysis of the Projection of Common Iliac Veins in Patients with Deep Vein Thrombosis
No full textDeep vein thrombosis (DVT) of the lower limb is characterised by the formation of abnormal blood clots in deep veins of lower
extremity. Changes in blood flow have been associated with an increased
risk of thrombus development. Understanding the relationship between
variable venous anatomy and haemodynamics can reveal insights to support clinical decision-making processes. The purpose of this study was
to combine statistical shape modelling (SSM) - to analyse venous shape
- and computational fluid dynamics (CFD) - to estimate blood flow -
in the common iliac vein to demonstrate the feasibility of a combined
framework to support the treatment of DVT. Principal geodesic analysis was used to extract dominant shape modes from a set of 24 venous
shapes in 2D: 8 patient-specific extracted from standard angiograms and
16 synthetic complementing the set. Steady-state CFD simulations were
run on the associated 3D geometries. Low wall shear stress distributions
below three thresholds (< 0.15, < 0.10, < 0.05P a) were the haemodynamic risk metrics of choice. The distribution of CFD output metrics
was evaluated using the three most dominant shape modes from PGA
and compared to the three modes that showed the strongest correlation
with the CFD metrics, illustrating that they are not the same. The study
demonstrated the feasibility of combining SSM and CFD to examine the
importance of shape variability and inflow in a local region of the venous
circulation. It will serve as a basis for extended work on a larger set of
venous shapes extracted from standard medical images
Thermodynamics of stacking faults in GaAs-based system revealed by in-situ heating in TEM
No full textStacking faults (SFs) are a type of two-dimensional defect that can significantly degrade the performance of III-V semiconductor devices. In this study, we investigate the thermal evolution of intrinsic SFs in (In)GaAs-on-Si systems using in-situ heating in an aberration-corrected scanning transmission electron microscopy. Our results indicate that chiral intrinsic SFs near the InGaAs/GaAs interface undergo thermally induced migration and interaction, leading to the formation of Lomer-Cottrell locks at 700 °C. Between 200 and 700 °C, SFs exhibit sliding behaviour, which triggers their reaction into a characteristic three-layer defect (TLD) structure, which could be quickly annihilated during the baking environment. Using Lorentz transmission electron microscopy (LTEM) to image magnetization configurations, we observed the formation of intrinsic stacking fault (SF)-induced magnetic vortices. These vortices arise from the competition between the Heisenberg exchange interaction and the Dzyaloshinskii-Moriya interaction (DMI). Notably, as field-driven dipole oscillations intensify, the magneto-Stark effect enables manipulation of transitions between out-of-plane and in-plane magnetic vector fields. This work advances the understanding of defect dynamics in III-V compound semiconductors and provides new strategies for tailoring crystal quality during epitaxial growth