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Strong discrete Morse theory
Full text linkThe purpose of this work is to develop a version of Forman’s discrete Morse theory for simplicial complexes, based on internal strong collapses. Classical discrete Morse theory can be viewed as a generalization of Whitehead’s collapses, where each Morse function on a simplicial complex defines a sequence of elementary internal collapses. This reduction guarantees the existence of a CW-complex that is homotopy equivalent to , with cells corresponding to the critical simplices of the Morse function. However, this approach lacks an explicit combinatorial description of the attaching maps, which limits the reconstruction of the homotopy type of . By restricting discrete Morse functions to those induced by total orders on the vertices, we develop a strong discrete Morse theory, generalizing the strong collapses introduced by Barmak and Minian. We show that, in this setting, the resulting reduced CW-complex is regular, enabling us to recover its homotopy type combinatorially. We also provide an algorithm to compute this reduction and apply it to obtain efficient structures for complexes in the library of triangulations by Benedetti and Lutz
Geospatial Analysis of Population Exposure to Flooding in the Sudd Region, South Sudan
Full text linkThe Sudd wetland in South Sudan extends over 90,000 km2. Large‐scale flood events in recent years (2019–2022) are said to have led to the displacement of an estimated 1.8 million people in total. However, these estimates are approximate and to date there has not been a systematic analysis of population exposure to flooding in the Sudd region. This study seeks to address this gap by using global flood modeling, satellite observations of flood extent, and global gridded population datasets to analyze population exposure. Recognizing the inevitable limitations of these datasets, we intersect all the available global flood mapping and population datasets. The results indicate that 0.8–2.9 million people are currently exposed to the 100‐year return period flood extent, depending on the flood model and population dataset used. Aggregated results of the model agreement intercomparison indicate that all five global models agree on key flood‐prone areas within and around the Sudd, which is further corroborated with satellite flood observations. Intercomparison of the population density among the four georeferenced population products demonstrates that WorldPop and GHSL‐Pop population distributions better represent the patterns of the Sudd rural settlements that are typically in forms of clusters. The uncertainty in exposure estimates is attributable to variations in both flood outlines and geospatial population estimates. These findings provide hitherto unavailable insights into flood exposure in South Sudan, to inform flood management decisions and disaster reduction responses in the Sudd region. This study demonstrates the global significance of model intercomparison as best practice for any flood exposure analysis to underpin policy and decision‐making in Africa and other data‐scarce regions
Lexical inference training for homonyms: Two randomized controlled trials for children with English as a first and an additional language
Full text linkBackground: Many words have multiple meanings, which present challenges to learning, yet research has yet to identify effective interventions for homonyms. Lexical inference may be a promising strategy. Aim: To evaluate a brief, novel lexical inference intervention for homonyms. Samples: Children aged 7–8 years (Study 1: N = 180, Study 2: N = 76). Study 2 included children with English as an Additional Language (EAL, n = 37). Methods: In two randomized controlled trials, participants were assigned to either inference training or control (Study 1: spatial training; Study 2: implicit exposure through reading). Their receptive knowledge of taught and untaught homonyms was measured before and after the intervention, and in Study 2, metacognitive and inference skills too. Results: Those in the inference interventions showed greater gains in receptive knowledge than control groups. In Study 2, children also showed improvement in the inference test with homonyms, and while children with EAL had a specific challenge with receptive knowledge of homonyms compared to their EL1 peers, the intervention was equally effective for both groups. Receptive knowledge and inference with homonyms predicted unique variance in reading comprehension. The intervention showed limited transfer to untaught words, although patterns of errors provided some indication of improved understanding. Conclusions: A brief inference training is effective for gaining knowledge of homonyms, with limited transfer to untaught words, and the intervention is equally effective for children with EAL and EL1. The findings also showed the importance of homonym understanding and inference for children's reading comprehension
Forecasting climate change using a multivariate cointegrated system
Full text linkA cointegrated vector equilibrium correction model of key climate variables including sea surface temperature, ocean heat content, Arctic sea-ice extent and sea-level change is built, driven by radiative forcing in which a stochastic trend arises due to anthropogenic emissions of greenhouse gases. A valid and congruent statistical model requires saturation estimation to model breaks in trends, while also conditioning on natural radiative forcings and El Ni˜no–Southern Oscillation. The model is stable over 150 years, reflecting the slow adjustment of the deep oceans to increased greenhouse gas concentrations, and predicts an equilibrium climate sensitivity of 2.6 ◦C. Projections out to 2100 highlight the many uncertainties over the coming decades
Links between COVID-19, long COVID and neurodegeneration: the role of glycosphingolipids
Full text linkGlycosphingolipids (GSLs) play major roles in viral infections, via viral entry and egress from cells in lipid rafts, but GSLs are also important in neurodegenerative diseases. The role of GSLs in acute COVID-19 infection is critical, although less studied in the sequelae of long COVID (Post-COVID Condition), but as the same enzymes controlling GSL metabolism are critical for viral entry and exit, neuromuscular junctions, neurological function, and cellular metabolism, it is important to define whether long COVID may increase the risk of subsequent neurodegeneration. SARSCoV-2 infection changes lipid metabolism, oxygen use, and can bind to and modify the expression of neurotrophic GSLs such as GM1 ganglioside. GM1 (Neu5Ac) is humanspecific, probably evolved as a result of a pandemic 3 - 2.5 million years ago that drove its selection. GM1 is a co-receptor with ACE2 for SARS-CoV-2, while also being a neurotrophin. Viral multiplication takes place in the endoplasmic reticulum/Golgi apparatus where GSLs are synthesized. This review defines the complex interaction between viruses, GSLs and neurodegeneration, which provides new perspectives on the interlinked metabolic changes. A European working group has been set up to assess risks of neurodegeneration with long COVID, based on potential GSL-mediated mechanisms
How has double reduction policy changed the education strategies and experiences of parents of migrant children in Zhangbei county: a case study in an underdeveloped area of China
Full text linkThis study investigates the impact of China’s “Double Reduction Policy” (DRP) on the educational strategies and experiences of parents of migrant children in Zhangbei County, a town in an underdeveloped area in China. Implemented in 2021, DRP endeavours to alleviate academic pressures and redirect the focus of education towards a more holistic and well-rounded development of students. Through a qualitative case study approach, this research explores how the DRP has influenced parental engagement in their children's education, focusing on three dimensions: home-based involvement, school-based involvement, and academic socialization. The study’s findings reveal multifaceted parental responses to the DRP. There is an evident shift towards valuing comprehensive development, proved by the increased emphasis on health, personal interests, and a love for learning. Following this shift, parents employ diverse strategies, including encouraging children to do sports, contact nature, use online resources to develop hobbies, take study tours, and read books. However, the persistence of the cultural significance of academic achievement and high-stakes testing continues to shape parental strategies. For instance, parents maintain expectations and inspirations for children’s academic achievement, so they would actively provide extra-curricular practices. Between the two groups of interviewees, there are considerable differences. The housewives, constrained by financial limitations and lower educational backgrounds, maintain a more traditional academic focus. In contrast, vocational teacher parents demonstrate greater openness to alternative educational pathways, such as vocational education, and employ innovative methods like study tours to nurture diverse interests and skills in their children. This research contributes to the existing literature by offering insights into the dynamics of educational strategy adaptation under a new policy among migrant parents in underdeveloped areas, a perspective overlooked in previous research. The implications underscore the necessity for targeted support mechanisms to empower parents, advocate a deep reflection on the stratification of higher education, and highlight the potential of vocational education as a viable and valued pathway
Circus arts shine a spotlight on antimicrobial resistance in Cambodia
Full text linkBackground: In Cambodia, limited conceptual understanding of antimicrobials and the wide availability of over-the-counter medications increases antimicrobial resistance (AMR) threats. Community-based campaigns are critical to foster fundamental concepts of antimicrobials, their appropriate use and potential consequences of AMR. Methods: A circus-based drama on AMR was co-designed with a non-profit arts school and local youth groups, in coordination with two provincial health authorities. Results: Events held across three venues were attended by >1200 people and the accompanying social media campaign received >0.5 million views. Conclusions: Following the success of the campaign, the circus drama’s key messages are being developed into educational materials for school children nationwide
Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae from human carriage, the human-polluted environment, and food: Molecular epidemiology of two prospective cohorts in five European metropolitan areas
Full text linkObjectives: For 475 ESBL-producing Escherichia coli (ESBL-Ec), and 171 ESBL-producing Klebsiella pneumoniae (ESBL-Kp) collected from human carriers, the human-polluted (hp)-environment, and food: (i) to compare the antimicrobial resistance gene (ARG) content, and (ii) to assess clonal relationships between human and non-human isolates. Materials and methods: Two prospective multicenter cohorts were assessed: colonized hospitalized index-subjects and household contacts, and long-term care facility (LTCF) residents. Additionally, linked hp-environment and food samples were collected. Presence of ARGs were assessed using pairwise comparisons and proportional similarity index (PSI). Clonal relationships were assessed using cgMLST distance visualizations and maximum likelihood phylogeny. Results: ESBL-Ec and ESBL-Kp co-occurred in 14/65 households, 3/6 LTCFs, and in 33/202 of ESBL-positive participants. Thirty-nine percent of detected ARG types were found in both species (36/93). Frequencies of beta-lactamase, ESBL, aminoglycoside, and sulfonamide ARG types from human ESBL-Ec and ESBL-Kp overlapped considerably: PSIs 0.59–0.75, and were equal or higher compared to the overlap between ESBL-Ec from humans and food isolates: PSIs 0.33–0.72. Isolates from humans and the hp-environment were frequently clonally related, indicating human contamination of the environment. Links with food isolates were observed less frequently. For ESBL-Ec both interregional and regional clonal dissemination were observed, while for ESBL-Kp clonal dissemination was mainly regional. Conclusions: ESBL-Ec and ESBL-Kp from human carriage showed considerable overlap in ARG content. Furthermore, clonal links were observed frequently between humans and hp-environment, and with lower frequency between humans and food. These findings are consistent with human-to-human transmission as an important driver of ARG spread in humans