Alex Alarcon, Andrew P. Hearin, Matthew R. Becker
et al.
We present DiffstarPop, a differentiable forward model of cosmological populations of galaxy star formation histories (SFH). In the model, individual galaxy SFH is parametrized by Diffstar, which has parameters $θ_{\rm SFH}$ that have a direct interpretation in terms of galaxy formation physics, such as star formation efficiency and quenching. DiffstarPop is a model for the statistical connection between $θ_{\rm SFH}$ and the mass assembly history (MAH) of dark matter halos. We have formulated DiffstarPop to have the minimal flexibility needed to accurately reproduce the statistical distributions of galaxy SFH predicted by a diverse range of simulations, including the IllustrisTNG hydrodynamical simulation, the Galacticus semi-analytic model, and the UniverseMachine semi-empirical model. Our publicly available code written in JAX includes Monte Carlo generators that supply statistical samples of galaxy assembly histories that mimic the populations seen in each simulation, and can generate SFHs for $10^6$ galaxies in 1.1 CPU-seconds, or 0.03 GPU-seconds. We conclude the paper with a discussion of applications of DiffstarPop, which we are using to generate catalogs of synthetic galaxies populating the merger trees in cosmological N-body simulations.
Generative recommendation, which directly generates item identifiers, has emerged as a promising paradigm for recommendation systems. However, its potential is fundamentally constrained by the reliance on purely autoregressive training. This approach focuses solely on predicting the next item while ignoring the rich internal structure of a user's interaction history, thus failing to grasp the underlying intent. To address this limitation, we propose Masked History Learning (MHL), a novel training framework that shifts the objective from simple next-step prediction to deep comprehension of history. MHL augments the standard autoregressive objective with an auxiliary task of reconstructing masked historical items, compelling the model to understand ``why'' an item path is formed from the user's past behaviors, rather than just ``what'' item comes next. We introduce two key contributions to enhance this framework: (1) an entropy-guided masking policy that intelligently targets the most informative historical items for reconstruction, and (2) a curriculum learning scheduler that progressively transitions from history reconstruction to future prediction. Experiments on three public datasets show that our method significantly outperforms state-of-the-art generative models, highlighting that a comprehensive understanding of the past is crucial for accurately predicting a user's future path. The code will be released to the public.
L. Filipe O. Costa, Francisco Frutos-Alfaro, José Natário
et al.
In a recent paper we discussed when it is possible to define reference frames nonrotating with respect to distant inertial reference objects (extension of the IAU reference systems to exact general relativity), and how to construct them. We briefly review the construction, illustrating it with further examples, and caution against the recent misuse of zero angular momentum observers (ZAMOs).
Severe dengue virus infection (DVI) is characterized by thrombocytopenia and plasma leakage (PL) due to the release of vasoactive cytokines by immune cells such as monocytes, lymphocytes, neutrophils, and platelets in response to dengue virus (DENV). This immune response triggers systemic inflammation, altering monocyte, lymphocyte, and neutrophil kinetics, which in turn affects leukocyte differentials. PL is indicated by an increase in hematocrit (Hct). This study aims to evaluate the potential use of the Aggregate Index of Systemic Inflammation (AISI) as an indicator of plasma leakage. A correlative analytical study with a cross-sectional approach was conducted on 70 pediatric DVI patients diagnosed according to the 2009 WHO criteria and confirmed by anti-DENV IgM/IgG tests. Patients with a history of malignancy, autoimmune thrombocytopenic purpura, or secondary DVI were excluded. Absolute neutrophil, monocyte, platelet, and lymphocyte counts, AISI, and Hct levels were obtained from complete blood count results using a hematology analyzer. The results showed that AISI and lymphocytes correlated with Hct, with correlation values of (r=0.410, p<0.001) and (r=0.446, p<0.001), respectively. In contrast, monocytes, neutrophils, and platelets did not correlate with Hct, with correlation values of (r=-0.009, p=0.942), (r=-0.059, p=0.628), and (r=-0.175, p=0.147), respectively. In conclusion, AISI levels in DVI were low and negatively correlated with Hct, a known indicator of PL. These findings suggest that AISI has potential as a marker for PL and disease severity in DVI.
<i>Dies Buch gehört dem König</i> (<i>This Book Belongs to the King</i>), written and published in 1843 by the German Romantic author Bettina von Arnim, is a quasi-open letter, presented as a series of fictional dialogues with traces of a novel. Dedicated to the newly crowned King of Prussia, Friedrich Wilhelm IV, the letter unfolds social grievances and aims to persuade Friedrich Wilhelm to act like a just king. Due to its delicate socio-critical impetus, the letter does so through strategies of obfuscation and by using a richly pictorial, seemingly naive and lavish way of speech rather than taking an openly reproachful stance. Crucially, von Arnim does not install herself as the letter’s speaker but instead fictionalizes the letter and presents Goethe’s mother, Catharina Elisabeth Goethe, as the letter’s primary voice (‘Frau Rat’). By using a well-respected figure of the ruling class as the letter’s main voice, von Arnim aimed at minimizing its scandalous potential. But even prior to publishing the letter, von Arnim had already managed to trick Friedrich Wilhelm and the Prussian censors herself: by fusing the book’s title and dedication, she paratextually outwitted both the censors and the King, whose permission she sought precisely to bypass Prussian censorship. This article shows how von Arnim managed to avoid a larger scandal both textually by implementing semi-fictional devices and paratextually by presenting the letter as an affirmation of Friedrich Wilhelm IV and his policies.
History of scholarship and learning. The humanities
In the theoretical study of distributed communication networks, "history trees" are a discrete structure that naturally models the concept that anonymous agents become distinguishable upon receiving different sets of messages from neighboring agents. By conveniently organizing temporal information in a systematic manner, history trees have been instrumental in the development of optimal deterministic algorithms for networks that are both anonymous and dynamically evolving. This note provides an accessible introduction to history trees, drawing comparisons with more traditional structures found in existing literature and reviewing the latest advancements in the applications of history trees, especially within dynamic networks. Furthermore, it expands the theoretical framework of history trees in new directions, also highlighting several open problems for further investigation.
BackgroundCognition disorders not only lead to adverse health consequences but also contribute to a range of socioeconomic challenges and diminished capacity for performing routine daily activities. In the digital era, understanding the impact of digital exclusion on cognitive function is crucial, especially in developing countries.
ObjectiveThis study aimed to evaluate the association between digital exclusion and cognitive function among elderly populations in developing countries.
MethodsUsing data from CHARLS (China Health and Retirement Longitudinal Study) from 2011 to 2020 and MHAS (Mexican Health & Aging Study) from 2012 to 2021, we defined digital exclusion as self-reported absence from the internet. Cognitive function was assessed through 5 tests: orientation, immediate verbal recall, delayed verbal recall, serial 7s, and figure recall. Cognitive function was assessed in 2 categories: worse cognition (a categorical variable that classifies cognition as either better or worse compared to the entire cohort population) and cognitive scores (a continuous variable representing raw cognitive scores across multiple follow-up waves). Logistic regression analyses and generalized estimating equation (GEE) analyses were used to examine the relationship between cognitive function and digital exclusion, adjusting for potential confounders, including demographics, lifestyle factors, history of chronic diseases, basic activities of daily living (BADL) disability, instrumental activities of daily living (IADL) disability, and basic cognitive abilities.
ResultsAfter excluding participants with probable cognitive impairment at baseline and those who did not have a complete cognitive assessment in any given year (ie, all tests in the cognitive assessment must be completed in any follow-up wave), a total of 24,065 participants in CHARLS (n=11,505, 47.81%) and MHAS (n=12,560, 52.19%) were included. Of these, 96.78% (n=11,135) participants in CHARLS and 70.02% (n=8795) in MHAS experienced digital exclusion. Adjusted logistic regression analyses revealed that individuals with digital exclusion were more likely to exhibit worse cognitive performance in both CHARLS (odds ratio [OR] 2.04, 95% CI 1.42-2.99; P<.001) and MHAS (OR 1.40, 95% CI 1.26-1.55; P<.001). Gender and age did not significantly modify the relationship between digital exclusion and worse cognition (intervention P>.05). The fully adjusted mean differences in global cognitive scores between the 2 groups were 0.98 (95% CI 0.70-1.28; P<.001) in CHARLS and 0.50 (95% CI 0.40-0.59; P<.001) in MHAS.
ConclusionsA substantial proportion of older adults, particularly in China, remain excluded from internet access. Our study examined longitudinal changes in cognitive scores and performed cross-sectional comparisons using Z-score standardization. The findings suggest that digital exclusion is linked to an increased risk of cognitive decline among older adults in developing countries. Promoting internet access may help mitigate this risk and support better cognitive health in these populations.
Computer applications to medicine. Medical informatics, Public aspects of medicine
The paper re-examines the principal methodological questions, arising in the debate over the cosmological standard model's postulate of Dark Matter vs. rivalling proposals that modify standard (Newtonian and general-relativistic) gravitational theory, the so-called Modified Newtonian Dynamics (MOND) and its subsequent extensions. What to make of such seemingly radical challenges of cosmological orthodoxy? In the first part of our paper, we assess MONDian theories through the lens of key ideas of major 20th century philosophers of science (Popper, Kuhn, Lakatos, and Laudan), thereby rectifying widespread misconceptions and misapplications of these ideas common in the pertinent MOND-related literature. None of these classical methodological frameworks, which render precise and systematise the more intuitive judgements prevalent in the scientific community, yields a favourable verdict on MOND and its successors -- contrary to claims in the MOND-related literature by some of these theories' advocates; the respective theory appraisals are largely damning. Drawing on these insights, the paper's second part zooms in on the most common complaint about MONDian theories, their ad-hocness. We demonstrate how the recent coherentist model of ad-hocness captures, and fleshes out, the underlying -- but too often insufficiently articulated -- hunches underlying this critique. MONDian theories indeed come out as severely ad hoc: they do not cohere well with either theoretical or empirical-factual background knowledge. In fact, as our complementary comparison with the cosmological standard model's Dark Matter postulate shows, with respect to ad-hocness, MONDian theories fare worse than the cosmological standard model.