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Exponential asymptotics for translational modes in the discrete nonlinear Schrödinger model
Get PDFIn the present work, we revisit the topic of translational eigenmodes in discrete models. We focus on the prototypical example of the discrete nonlinear Schr¨odinger equation, although the methodology presented is quite general. We tackle the relevant discrete system based on exponential asymptotics and start by deducing the well-known (and fairly generic) feature of the existence of two types of fixed points, namely site-centered and inter-site-centered. Then, turning to the stability problem, we not only retrieve the exponential scaling (as e−π2/(2ε), where ε denotes the spacing between nodes) and its corresponding prefactor power-law (as ε−5/2), both of which had been previously obtained, but we also obtain a highly accurate leading-order prefactor and, importantly, the next-order correction, for the first time, to the best of our knowledge. This methodology paves the way for such an analysis in a wide range of lattice nonlinear dynamical equation models
Caring and sharing: global analysis of happiness and kindness
Get PDFWorld Happiness Report 2025: Chapter 2
Efficacy of artemisinin-based combination therapy (ACT) in people living with HIV (PLHIV) diagnosed with uncomplicated Plasmodium falciparum malaria in Africa: a WWARN systematic review
Get PDFBackground: Africa bears the highest double burden of HIV and malaria worldwide. In 2023, an estimated 25.9 million people were living with HIV (PLHIV), and 246 million malaria cases were diagnosed in Africa. Malaria patients co-infected with HIV are considered at a higher risk of failing malaria treatment, according to the World Health Organization (WHO) guidelines. This systematic literature review aims to assess the treatment outcomes following artemisinin-based combination therapy (ACT) in PLHIV. Methods: The literature search was conducted up to April 2022 in the following databases: MEDLINE, EMBASE, Web of Science, Cochrane Central, WHO Global Index Medicus, Clinicaltrials.gov, and the WorldWide Antimalarial Resistance Network (WWARN) Clinical Trial Library. Studies describing any malaria treatment outcomes or anti-malarial drug exposure in PLHIV treated for uncomplicated Plasmodium falciparum malaria infection were eligible for inclusion. Results: A total of 26 articles describing 19 studies conducted between 2003 and 2017 in six countries were included in this review; it represented 2850 malaria episodes in PLHIV across various transmission settings. The most studied artemisinin-based combination was artemether-lumefantrine (in 16 studies). PLHIV were treated with various antiretroviral therapy (ART) regimens, namely efavirenz (EFV), nevirapine (NVP), atazanavir-ritonavir (ATVr), lopinavir-ritonavir (LPV/r), and/or on prophylaxis with trimethoprim-sulfamethoxazole (TS), or were untreated (in 3 studies). There was no evidence of an increased risk of recrudescence in PLHIV compared to those without HIV. When treated with artemether-lumefantrine, PLHIV receiving LPV/r had a lower risk of malaria recurrence compared to PLHIV on NVP-based or EFV-based ART, or those without HIV. LPV/r increased lumefantrine exposure and EFV-treated patients had a reduced exposure to both artemether and lumefantrine; NVP reduced artemether exposure only. Conclusions: Limited data on ACT outcomes or drug exposure in PLHIV in Africa remains a reality to date, and the effect of antivirals appears inconsistent in the literature. Considering the heterogeneity in study designs, these review’s findings support conducting an individual patient data meta-analysis to explore the impact of antiretroviral therapy on anti-malarial treatment. Trial registration: The protocol for the original search was published on PROSPERO with registration number CRD42018089860
Structure of mushy layers grown from perfectly and imperfectly conducting boundaries. Part 1. Diffusive solidification
Get PDFWe model transient mushy-layer growth for a binary alloy solidifying from a cooled boundary, characterising the impact of liquid composition and thermal growth conditions on the mush porosity and growth rate. We consider cooling from a perfectly conducting isothermal boundary, and from an imperfectly conducting boundary governed by a linearised thermal boundary condition. For an isothermal boundary we characterise different growth regimes depending on a concentration ratio, which can also be viewed as characterising the ratio of composition-dependent freezing point depression versus the temperature difference across the mushy layer. Large concentration ratio leads to high porosity throughout the mushy layer and an asymptotically simplified model for growth with an effective thermal diffusivity accounting for latent heat release from internal solidification. Low concentration ratio leads to low porosity throughout most of the mushy layer, except for a high-porosity boundary layer localised near the mush–liquid interface. We identify scalings for the boundary-layer thickness and mush growth rate. An imperfectly conducting boundary leads to an initial lag in the onset of solidification, followed by an adjustment period, before asymptoting to the perfectly conducting state at large time. We develop asymptotic solutions for large concentration ratio and large effective heat capacity, and characterise the mush structure, growth rate and transition times between the regimes. For low concentration ratio the high porosity zone spans the full mush depth at early times, before localising near the mush–liquid interface at later times. Such variation of porosity has important implications for the properties and biological habitability of mushy sea ice
Preterm birth and cardiometabolic health trajectories from birth to adulthood: the Avon Longitudinal Study of Parents and Children
Get PDFBackground: Adults who were born prematurely (<37 weeks gestation) are at increased cardiovascular disease risk, but it is unclear when in the life course this risk emerges. Our aim was to compare trajectories of
multiple cardiometabolic risk factors from childhood to early adulthood between those who had and had not been born preterm.
Methods and Results: Multilevel models were used to compare trajectories from early childhood (<9 years) to age 25 of BMI, fat and lean mass, systolic and diastolic blood pressure (BP), lipids, glucose and insulin, between individuals born preterm (N=311-676, range 25-36 gestation) and term (N=4973-10534) in a UK birth cohort study. We also investigated gestational age as a continuum. In children born preterm (versus term), systolic and diastolic BP were higher at age 7 (mean predicted differences 0.7mmHg;95%CI(-0.2,1.6) and 0.6mmHg;95%CI(-0.04,1.3), respectively). By age 18, the difference in SBP persisted (1.9mmHg;95%CI(0.8,3.1)) and in DBP (0.1mmHg;95%CI(-0.7,1.0))
disappeared. By age 25, this difference in SBP began to attenuate towards the null (0.9mmHg;95%CI(-0.5,2.3)) Participants born preterm (versus term) had lower BMI between ages 7 and 18, but by age 25, there was no difference. Fat and lean mass trajectories were consistent with BMI. HDL-c was higher and triglycerides lower at birth, in those born preterm, but this difference also
disappeared by age 25. There was no evidence of differences in glucose and insulin.
Conclusions: Few, modest differences in cardiometabolic health were found in those born preterm versus term. All disappeared by age 25, except the small difference in SBP. Longer follow-up is needed to establish if
and when cardiometabolic health trajectories diverge between these two groups
Heidegger and van Gogh’s Shoes
Get PDFMartin Heidegger’s discussion of one of Vincent van Gogh’s paintings of a pair of shoes plays a critical role in the development of his philosophy of art. Few passages in Heidegger’s entire corpus have occasioned more controversy and commentary than his short discussion of this painting. Reception of Heidegger’s philosophy of art has, to a surprising degree, been shaped by a sharply critical essay published by the art historian Meyer Schapiro in 1968, entitled ‘The Still Life as a Personal Object—A Note on Heidegger and Van Gogh’. In the decades since, Schapiro’s critique has set the terms of the debate over Heidegger’s interpretation of van Gogh’s painting. The near consensus view seems to be that, as Jeremy Gilbert-Rolfe puts it, ‘every fact enunciated by Schapiro in that attack […] is correct’. In this essay, however, I show that it is closer to the truth to say that every claim Schapiro made in his attack on Heidegger is false. Ever since, both critics and defenders of Heidegger have uncritically accepted and repeated Schapiro’s basic factual errors. Once the record is corrected, this opens up space for a reappraisal of Heidegger’s engagement with van Gogh’s shoes, which I offer in the concluding sections of the essay
Perspective: the foundations, fortunes and future of cognitive control research
Get PDFThis perspective considers the contribution of articles in the Journal of Experimental Psychology: Human Perception and Performance to our understanding of mechanisms of control that coordinate component processes of perception and action into an effective task set. Foundations of this research lie in 20th century debates about whether the fundamental challenge for control arises from capacity limits of serial, discrete processing stages or conflicts between parallel, continuous processes. Fortunes of the field have flourished in the 21st century with detailed studies of adaptive control supporting both flexible task switching and stable task performance in the face of distraction. Future directions are suggested regarding “macro” levels of control
Effects of data amount and variation in deep learning-based tuberculosis diagnosis in chest X-ray scans
Get PDFPulmonary tuberculosis ranks among the world’s deadliest diseases, causing devastating global health harm. Despite diagnosing millions annually, COVID-19’s aftermath and inadequate screening within developing countries interfered with diagnosis of tuberculosis, hindering proper treatment and increasing tuberculosis mortality. Our study aims to enhance diagnostic opportunities by developing a deep-learning model to categorize pulmonary X-ray scans into “normal” and “tuberculosis” classes. Exercising feature extraction, we incorporated VGG-16 (Visual Geometry Group network with 16 layers) architecture to enhance model classification accuracy via transfer learning. We hypothesized that models trained on a greater amount and variety of data would perform better than those trained on less invariable data. Testing our hypothesis, we developed four models with replicate architectures trained on pulmonary X-ray scans from the Montgomery County Chest X-ray Dataset (Dataset A), the Shenzhen Chest X-ray Dataset (Dataset B), the Tuberculosis Chest X-ray Database (Dataset C), and the combined data (Dataset A, B, and C). Data amount and variability increased from Dataset A to C and was the largest in the combined datasets. Testing these models on each dataset used in training, we found the mean accuracy values were 45.6% for Dataset A, 62.0% for Dataset B, 82.0% for Dataset C, and 95.9% for the combined dataset. This indicates that models trained on more data perform more accurately across datasets due to greater data variation and amount. Additionally, our study highlights the efficacy of deep learning models in tuberculosis diagnosis, emphasizing the importance of data variability and a wider pulmonary X-ray database for potential implementation in global health