Secular Changes Research Articles

Prevalence of and factors associated with lipid screening in young people aged 16– to 21 years in the United States: analysis of nationwide cross-sectional data

Background & AimsThere is no consensus on whether it is worthwhile for young people to undergo lipid screening. An estimate of the national prevalence of lipid screening in this population can serve as a basic parameter in analyses of the utilization and cost-effectiveness of health care services. Previous studies were mostly based on electronic health records or insurance claims data or were restricted to adolescents at younger ages. This study aimed to investigate the prevalence of lipid screening and the factors associated with it in young people aged 16– to 21 years in the United States based on a nationally representative sample.MethodsA cross-sectional study of 16- to 21-year-old participants from the National Health and Nutrition Examination Survey (NHANES), 2013–March 2020 (four cycles), was conducted. The prevalence of lipid screening uptake was calculated for each cycle as well as for all four cycles combined, and the associations of lipid screening uptake with the covariates were analysed by logistic regression. An appropriate sample weight was incorporated into the analysis as recommended.ResultsA total of 3,600 participants were included in the analysis, and 32.02% of them had ever received lipid screening at the time of the survey, with no statistically significant secular changes observed over the four cycles. Among the participants, 28.83% received lipid screening within the past 5 years. In multivariable regression analysis adjusted for all covariates, non-Hispanic black ethnicity (adjusted odds ratio [AOR]: 1.43), having health insurance (AOR: 1.54), obesity (AOR: 1.65) and sufficient physical activity (AOR: 1.36) were significantly associated with a greater chance of ever receiving lipid screening.ConclusionsNearly one-third of young people aged 16– to 21 years in the United States have received lipid screening. Ethnicity, health insurance, weight problems, and physical activity level were associated with the likelihood of lipid screening uptake. These findings could help people understand the current situation of lipid screening in young people in the United States and may serve as fundamental parameters in the assessment of the utilization and cost-effectiveness of related health care services.

Secular change in seaweed species composition and coverage of Sargassaceae on the artificial reef in Wakasa Bay, Japan.

The threat of declining seaweed beds has been a concern around the world. Seagrass and seaweed (brown algae) beds are essential habitats supporting fisheries. However, approximately 22% of these habitats have been lost in Japan due to increased coastal landfill sites and ports. This study aims to rehabilitate the depletion of these habitats by constructing an artificial reef in Wakasa Bay, Japan, and monitoring Sargassaceae succession in the second and fourth years after the construction was completed. In this study, we set up four sites on the artificial reef. Then we identified the seaweed species composition and coverage of the Sargassaceae using underwater visual observation by scuba divers. The seaweed coverage was already over approximately 80% in the second year after construction. The Sargassum horneri and S. confusum dominated during the first and second sampling in the second year after construction, and Myagropsis myagroides and S. patens during the third and fourth sampling in the fourth year after construction. Thus, the recovery of species composition takes longer than that of coverage. Therefore, observing species composition recovery is essential when constructing the artificial reef.

Light δD apatites reveal deep origin water in North China Craton intracontinental granites and basalts

Water is essential to the formation of intracontinental granites, but its origin remains elusive. Here we address this scientific problem by analyzing D/H isotopes of apatites, hydrous minerals in Jurassic and Early Cretaceous granites and basalts from eastern North China Craton, where water was previously interpreted as derived from subducting slab. Results reveal extremely low δD values in pristine Early Cretaceous granitic (−203‰ to −127‰) and basaltic (−197‰ to −107‰) apatites, contrasting with relatively high δD values (−137‰ to −47‰) in Jurassic granites. Given the depth-dependent D/H isotopic fractionation during slab dehydration and high-water contents in coeval primitive mafic magmas, the Early Cretaceous magma water is attributed to the stagnant slab within the mantle transition zone. Secular change in the depth of water aligns with steepening of subducting Paleo-Pacific plate from Jurassic to Early Cretaceous, demonstrating the potential of apatite H isotopes in tracing water origin in granites and basalts.

Zircon U-Pb Age and Hf-O Isotope Evidence of the Taihua Complex on the Southern Margin of the North China Craton: Implications for Its Magmatic Process During the Early Paleoproterozoic

The Xiaoqinling is the largest terrane of the Taihua Complex and records Paleoproterozoic silicic magmatism, which is one of the most potential areas for understanding secular changes in tectonic processes during the Tectono-Magmatic Lull (TML). In this study, we use zircon U–Pb dating, Lu–Hf and O isotopic analysis to constrain the age, provenance, and magmatic processes of the protoliths for the Paleoproterozoic granitic gneiss, tonalitic gneisses, and migmatitized tonalitic gneiss from the Xiaoqinling area. The isotopic composition of zircon provides a key proxy for querying the crustal record. Integration of our new U–Pb and Hf–O isotope data with available published data from other regions of the North China Craton (NCC), allows us to better assess the secular changes of the North China Craton during the magmatic lull at ∼2.3 Ga. This study shows that the protolith of the tonalitic gneisses in the study area have crust-like Hf–O isotopic compositions with slightly negative to positive εHf(t) (−3.0− +2.1) and low to moderately elevated δ18O values (2.71–7.87‰), indicating a mixed origin of continental crust assimilated by mantle-derived magmas.

Argentine reference charts for head circumference from birth to 19 years of age.

Introduction. Head circumference (HC) is an indicator of brain growth; growth charts are necessary to determine normal or pathological variations. Objectives. To present the first Argentine HC reference charts between birth and 19 years of age and to compare them with the Nellhaus charts, which have been used in our country to date. Population and methods. These references were developed based on combined data from the National Survey on Nutrition and Health of 2018 and cross-sectional studies conducted between 2004 and 2007 in the provinces of Buenos Aires and La Pampa, which included 8326 healthy children and adolescents. Growth curves were adjusted using the LMS method. To assess the differences between these reference charts and the Nellhaus charts, at different ages, the 2nd, 50th, and 98th percentiles were plotted. Results. HC showed a variable increase in size with age, which was greater in the first years of life, and a slight increase at puberty. The values for the 98th percentile of the Argentine reference charts werehigher than those of the Nellhaus charts at all ages. The values for the 2nd percentile of the national reference were lower than those of the Nellhaus charts during the first 2 years of life, similar between 3 and 7 years of age, and higher after this age. Conclusions. The Argentine curves adequately describe the growth pattern of HC. The differences found with the Nellhaus charts may be attributed to secular changes.

Quantifying the uniqueness and divisiveness of presidential discourse

Abstract Do American presidents speak discernibly different from each other? If so, in what ways? And are these differences confined to any single medium of communication? To investigate these questions, this paper introduces a novel metric of uniqueness based on large language models, develops a new lexicon for divisive speech, and presents a framework for assessing the distinctive ways in which presidents speak about their political opponents. Applying these tools to a variety of corpora of presidential speeches, we find considerable evidence that Donald Trump’s speech patterns diverge from those of all major party nominees for the presidency in recent history. Trump is significantly more distinctive than his fellow Republicans, whose uniqueness values appear closer to those of the Democrats. Contributing to these differences is Trump’s employment of divisive and antagonistic language, particularly when targeting his political opponents. These differences hold across a variety of measurement strategies, arise on both the campaign trail and in official presidential addresses, and do not appear to be an artifact of secular changes in presidential communications.

Sustained decline in birth weight and increased rate of preterm infants born small for gestational age in Japan.

Birth weights have continued to decline in Japan in recent years. However, secular trend changes such as the birth weight relative to the week of gestation remain to be explored. This study aimed to determine the trends over time in mean birth weight and small for gestational age (SGA) rate for each gestational week. We used a large dataset of 27,015,792 births obtained from birth certificates between 1997 and 2021. Births from 22 to 41 weeks of gestation were evaluated in six groups (22-24, 25-27, 28-31, 32-33, 34-36, and 37-41 weeks of gestational age). For each group, secular trend changes in the z-scores calculated from standard birth weight values were assessed. Time trends in the proportion of SGA and mean birth weight z-scores were evaluated using the Cochran-Armitage trend test and linear regression analysis. Binomial logistic regression was performed to ascertain the effects of gestational age, sex, primiparity, number of births, and maternal age on the likelihood of SGA. The mean birth weight of preterm infants continued to decrease, and the z-score for mean birth weight decreased linearly, falling to -0.7 at 25-27 weeks of gestation from 1997-2001 (first period) to 2017-2021 (final period). Maternal age continued to increase from the first period to the last period for all weeks of gestation. There was a linear increase in the SGA rate in preterm infants born at <34 weeks. Odds ratios for the likelihood of SGA were 1.3 times higher for maternal age ≥40 years than that for 25-29 years (95% CI: 1.29-1.33, p < 0.001). In Japan, there has been a continuous decline in birth weight and an increase in the rate of preterm SGA infants.

Secular Changes in Growth in the Maya Village of Yalcoba: 1986-2023.

ABSTRACTObjectiveTo analyze the changes in children's height, weight, BMI and rates of stunting and overweight and obesity over three periods: 1986–1987, 1996–1998, and 2023 for the community of Yalcoba in the Yucatan Peninsula.Material and MethodsFour hundred forty (6‐to‐15 years) children measured in 2023 were compared with data obtained in 1986–1987 (n = 675) and 1996–1998 (n = 628). Z‐scores of height and BMI were calculated to estimate percentages of stunting and high BMI‐for‐age (overweight and obesity). Comparisons of anthropometric parameters by sex and age groups between years of measurement were performed through one way ANOVAs.ResultsDifferences in anthropometric parameters were significant in all age groups of both sexes. Boys measured in 2023 were, on average, 6.4 and 3.3 cm taller than boys measured in the 1980s and 1990s, respectively. Increases in girls were 12 and 7.3 cm, respectively. Average increases in weight of boys measured in 2023 were 7.9 kg compared to the 1980s and 5.8 kg compared to 1990s. Average increases in girls measured in 2023 were 11.3 kg compared to the 1980s, and 7.6 kg compared to the 1990s. Stunting between the 1980s and 1990s decreased by 15 percentage points and between the 1990s and 2023 decreased by 47 percentage points. The percent of children deemed overweight/obese during these periods increased from 8 to 12–50 by 2023.ConclusionResults reflect the overall trends seen in the Yucatan where stunting has decreased substantially but the numbers of overweight/obese youths have increased dramatically in the past 30 years.

Florida Current transport observations reveal four decades of steady state

The potential weakening of the Atlantic Meridional Overturning Circulation (AMOC) in response to anthropogenic forcing, suggested by climate models, is at the forefront of scientific debate. A key AMOC component, the Florida Current (FC), has been measured using submarine cables between Florida and the Bahamas at 27°N nearly continuously since 1982. A decrease in the FC strength could be indicative of the AMOC weakening. Here, we reassess motion-induced voltages measured on a submarine cable and reevaluate the overall trend in the inferred FC transport. We find that the cable record beginning in 2000 requires a correction for the secular change in the geomagnetic field. This correction removes a spurious trend in the record, revealing that the FC has remained remarkably stable. The recomputed AMOC estimates at ~26.5°N result in a significantly weaker negative trend than that which is apparent in the AMOC time series obtained with the uncorrected FC transports.

Trends in Body Mass Index Among Individuals With Neurodevelopmental Disorders

Neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) are increasingly common. Individuals with NDDs have heightened obesity risks, but long-term data on body mass index (BMI) trends over time in this population are lacking. To assess secular BMI changes from 2004 to 2020 among children with NDDs compared with those without NDDs. This repeated cross-sectional study used data from the Child and Adolescent Twin Study in Sweden. Children born between January 1, 1992, and December 31, 2010, were screened for neurodevelopmental symptoms using the Autism-Tics, ADHD, and Other Comorbidities inventory between July 2004 and April 2020 when they were 9 or 12 years of age. Data analysis was conducted between September 27, 2023, and January 30, 2024. BMI percentiles (15th, 50th, and 85th) were modeled using quantile regression and compared between youths with and without NDDs. Secular changes in BMI percentiles over time spanning 2004 to 2020 were evaluated and stratified by NDD subtype. The cohort included 24 969 Swedish twins (12 681 [51%] boys) born between 1992 and 2010, with mean (SD) age of 9 (0.6) years. Of these, 1103 (4%) screened positive for 1 or more NDDs, including ADHD, ASD, and/or learning disability. Results indicated that at the 85th BMI percentile, there was a greater increase in BMI from 2004 to 2020 among youths with NDDs compared with those without NDDs (β for interaction [βint] between NDD status and time, 1.67; 95% CI, 0.39-2.90). The greatest divergence was seen for ASD (βint, 2.12; 95% CI, 1.26-3.70) and learning disability (βint, 1.92; 95% CI, 0.65-3.82). Within the latest cohort (2016-2020), the 85th BMI percentile was 1.99 (95% CI, 1.08-2.89) points higher among children with NDDs compared with those without NDDs. In this repeated cross-sectional study, at the higher end of the BMI distribution, children with NDDs had significantly greater increases in BMI compared with peers without NDDs over a 16-year period, highlighting an increasing risk of overweight over time in youths with NDDs compared with those without NDDs. Targeted obesity prevention efforts for this high-risk population are needed.

Epidemiology of deep vein thrombosis.

Deep vein thrombosis (DVT) is a cause of considerable morbidity worldwide. It is a common clinical disease in the daily practice of several medical disciplines including general medicine, angiology, and internal medicine, as well as of interest to public health because of its preventability and its sensitivity to secular changes in the distribution of population risk factors. In this review we present a comprehensive overview of the epidemiological features of DVT, including incidence and risk factors. Additionally, we give an overview of the burden that DVT poses on modern health care systems.

A Reference Model of Crustal Thickness and Vp/Vs of Western Canada

AbstractThe Canadian Cordillera marks a transition region from the current plate boundary through the Phanerozoic Cordilleran orogen to the Precambrian cratons. Knowledge of the subsurface structure of western Canada has been greatly advanced by seismological investigations during the past two decades, pioneered by the Lithoprobe project and, more recently, by regional passive seismic arrays. In this study, we construct a new model (WCANM22) of crustal thickness and P‐ to S‐wave velocity ratio, or Vp/Vs, by compiling receiver function data from 473 stations and existing constraints from over 2,600‐km long active source experiments. Our model covers a broad swath (about 1/4) of the land area of North America (105°–140°W, 48°–72°N) and shows an overall flat Moho beneath the Cordillera with an average depth of ∼36 km and a standard deviation of 3 km across orogenic belts. This study provides a comprehensive catalog of Vp/Vs in western Canada and reveals a moderate correlation between Poisson's ratio and the age of crustal domains. The average Vp/Vs values are 1.72, 1.79, and 1.82 for the Phanerozoic Cordillera, Proterozoic Cratons, and Archean‐aged Medicine Hat Block, respectively, suggesting continued modifications to crustal composition through episodic tectonothermal events. This distinct trend in western Canada sheds new light on the debated role of secular changes in the composition of continental crust.

The impact of hygienic living conditions on the differentiation of male body height at the beginning of the twentieth century in the USSR

BackgroundThe positive changes in hygienic living conditions are commonly believed to explain secular changes in body height and the age of maturity. However, it is difficult to estimate the separate impacts of these factors due to the lack of social and economic data and variations in the sources of information.We hypothesized that final male body height could be associated with various socioeconomic indicators, such as the development of the medical care system, the quality of nutrition, and the level of sanitary and hygienic conditions. Moreover, we hypothesized that male body height could be associated with the level of morbidity in the region during the time of conscript childhood (from 1 to 7 years old).Materials and methodsWe used two main sources of information in the analyses. The first is the data from the Statistical Reference Book published by the Central Statistical Committee in 1929. The second is the annual data from the Statistical Reference Book published in the Russian Empire. Since the conscripts were born between 1906 and 1909, we used datasets from 1910 to 1913. To analyze the data, we used a method of analyzing interacting variables called St. Nicolas House Analysis (SNHA).ResultsOur analyses revealed direct associations between the morbidity of some diseases and male body height and other anthropometric parameters.ConclusionsThere are associations between conscript final body height and the morbidity of influenza, dysentery and some venereal diseases, such as chancroid and syphilis. There were no associations between conscript final body height and the level of morbidity during childhood. However, other final parameters, such as BMI, weight, and chest circumference, could be associated with the morbidity of malaria, scabies, scurvy, and scarlet fever during childhood. The prevalence of these diseases could be strongly connected with unfavorable living conditions. The results are similar for both urban and rural areas.

Probing secular changes in the gravitational constant with white dwarf spectra

Exploring variations in fundamental physics constants across cosmological space-time is of substantial importance in both theoretical and experimental physics. A crucial means of investigating such variations involves comparing laboratory measurements with astrophysical observations. In the present study, we employ a combination of laboratory data and observed Lyman transitions of H2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_2$$\\end{document} identified in the white dwarf star GD133. Through this examination, we find the temporal variation of the gravitational constant, G˙/G=(0.016±0.098)×10-15year-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\dot{G}}}/{G} = (0.016 \\pm 0.098) \ imes 10^{-15}~\ ext {year}^{-1}$$\\end{document} with a gravitational potential ϕ≈104,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi \\approx 10^4,$$\\end{document} and an average total redshift of H2,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H_2,$$\\end{document}zabs=0.0001820(10).\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$z_{abs} =0.0001820(10).$$\\end{document} This newly determined constraint on the time variation of G serves as an important tool for advancing discussions within unified theories.

Craniometric Relationships of Migrant Victims of the April 18, 2015 Shipwreck Off the Coast of Libya

One of the most tragic events involving African migrants’ attempts to get to Europe was the 2015 shipwreck off the coast of Libya. More than 300 crania were recovered and are currently in the Laboratory of Forensic Anthropology and Odontology, Milan, Italy, where attempts are being made to identify them. This paper analyzes the cranial morphometrics in relation to what is known of African cranial variation. It also addresses questions of population subdivision on the ship as well as secular changes that may be reflected in cranial morphology.Crania were digitized using the 3skull software, which also computes Howells measurements from the coordinates. Migrant crania were compared to African reference samples consisting of both 19th-century sub-Saharan West Africans and East Africans. Statistical procedures were discriminant and canonical variate analysis and Mahalanobis distances. K-means unsupervised clustering was also used.Results showed that the migrant samples differed from the 19th-century samples systemically; the differences consisted mainly of lower facial projections and higher cranial vaults and bases. Position on the ship, whether on the deck or below in the holds, showed subdivision. Holds had a higher proportion of West Africans, and the deck had a higher proportion of East Africans. K-means clustering also found groups contrasting between the deck and the holds. Comparing migrant cranial morphology to 19th-century Africans using variables that respond to secular change showed that migrants reflect changes that have occurred in Africa over the past 200 years.We conclude that morphometric analysis can provide useful information concerning the composition of unidentified victims of tragic events such as the 2015 shipwreck.

Trends in Presentation and Management of Endogenous Hyperinsulinaemic Hypoglycaemia Over the Last Three Decades at a Tertiary Care Centre (1992-2022).

Endogenous hyperinsulinaemic hypoglycaemia (EHH) is characterized by inappropriate insulin secretion from pancreatic beta cells despite low blood glucose concentrations. We aimed to evaluate the secular changes in presentation and management of EHH due to insulinoma/non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS) at our centre. This was a single-centre ambispective study (2014-2022). The clinical, biochemical, hormonal and radiological parameters (n = 63) collected as part of this study were compared with our earlier studies (1992-2005, n = 31; and 2006-2013, n = 35) and with other centres across the world. A total of 63 patients (39 males) with a preoperative diagnosis of EHH (insulinoma, n = 58; and NIPHS, n = 5) and a mean age of 40.7 years were studied. The mean lag time from the onset of symptoms to diagnosis decreased from 4.6 years during the first study period to 1.9 years during this study period. However, the majority presented with fasting hypoglycaemia of 98.4%, and both fasting and postprandial hypoglycaemia of 32%. Exclusive postprandial hypoglycaemia was present in 1.7% of insulinoma. A histopathological diagnosis of insulinoma was made in 52 patients and nesidioblastosis in two patients. Intraoperative ultrasonography (IOUS) and intraoperative palpation (IOP) yielded 100% sensitivity, while endoscopic ultrasonography (EUS) and 68Ga-DOTA-Exendin-4 positron emission tomography/computed tomography (PET/CT) yielded sensitivity of 86% and 85%, respectively, for localizing insulinoma. Resolution of hypoglycaemia was noted in 53 of 57 (93%) patients who underwent surgery with a preoperative diagnosis of insulinoma. We observed a trend towards earlier diagnosis of EHH, increased patient numbers and availability of nuclear imaging techniques for preoperative localization in the last decade compared to earlier.

Changes in the prevalence of maternal chronic conditions during pregnancy: A nationwide age-period-cohort analysis.

To estimate temporal changes in the prevalence of pre-existing chronic conditions among pregnant women in Sweden and evaluate the extent to which secular changes in maternal age, birth cohorts and obesity are associated with these trends. Population-based cross-sectional study. Sweden, 2002-2019. All women (aged 15-49 years) who delivered in Sweden (2002-2019). An age-period-cohort analysis was used to evaluate the effects of age, calendar periods, and birth cohorts on the observed temporal trends. Pre-existing chronic conditions, including 17 disease categories of physical and psychiatric health conditions recorded within 5 years before childbirth, presented as prevalence rates and rate ratios (RRs) with 95% confidence intervals (CIs). Temporal trends were also adjusted for pre-pregnancy body mass index (BMI) and the mother's country of birth. The overall prevalence of at least one pre-existing chronic condition was 8.7% (147 458 of 1 703 731 women). The rates of pre-existing chronic conditions in pregnancy increased threefold between 2002-2006 and 2016-2019 (RR 2.82, 95% CI 2.77-2.87). Rates of psychiatric (RR 3.80, 95% CI 3.71-3.89), circulatory/metabolic (RR 1.62, 95% CI 1.55-1.71), autoimmune/neurological (RR 1.69, 95% CI 1.61-1.78) and other (RR 2.10, 95% CI 1.99-2.22) conditions increased substantially from 2002-2006 to 2016-2019. However, these increasing rates were less pronounced between 2012-2015 and 2016-2019. No birth cohort effect was evident for any of the pre-existing chronic conditions. Adjusting for secular changes in obesity and the mother's country of birth did not affect these associations. The burden of pre-existing chronic conditions in pregnancy in Sweden increased from 2002 to 2019. This increase may be associated with the improved reporting of diagnoses and advancements in chronic condition treatment among women, potentially enhancing their fecundity.

Excess weight and changes in body composition in boys and girls from La Plata district (Buenos Aires, Argentina) - a study with a secular perspective.

The aim of the present study was to advance knowledge of the secular changes in the prevalence of excess weight (overweight and obesity) and body composition of children living in different localities of La Plata district (Buenos Aires province, Argentina) over the last two decades. For this purpose, anthropometric data and information on the socioeconomic and environmental context of residence of schoolchildren aged 4.0-12.9 years collected during 2005-2009 (Cohort 1, n = 1 233) and 2016-2019 (Cohort 2, n = 1 499) were analysed and compared. From a secular perspective, the current analysis showed that the socioeconomic and environmental conditions of families living in La Plata district have deteriorated in recent decades. In this context, child excess weight increased by 13% and body composition was altered, mainly as a result of an increase in fat mass, without observing changes in the muscle component.

Non-evolutionary effects on period change in Magellanic Cepheids

Context. Period change studies offer a novel way to probe the evolution and dynamics of Cepheids. While evolutionary period changes have been well studied both observationally and theoretically, non-evolutionary period changes lack a systematic and quantitative description. Here, we deal with one such aspect of non-evolutionary period changes related to a crucial property, namely, the binarity-based nature of a Cepheid. With the advent of long-term photometry surveys covering Magellanic fields, the census of classical Cepheids in binary (or multiple) systems outside the Milky Way is timely. This may have implications for crucial aspects such as the period-luminosity relationship calibrations and our understanding of the nature of Cepheid companions. Aims. The overall objective is to have a quantitative understanding of the full picture of non-evolutionary period changes in Cepheids to develop a formalism to disentangle it from the secular evolutionary period change. In the first paper in the series, we aim to conduct a systematic search for non-evolutionary period changes to look for Cepheids in likely binary configurations and quantify their incidence rates in the Magellanic Clouds. Methods. We collected more than a decade-long time-series photometry from the publicly available, Optical Gravitational Lensing Experiment (OGLE) survey, with more than 7200 Cepheids altogether from the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). Our sample contains both fundamental-mode and first-overtone mode Cepheids. Then, we calculate d the observed minus calculated (O–C) diagrams to reveal the light-travel time effect (LTTE). Finally, we calculated the minimum companion masses of the Cepheids and compared them with the predictions from Cepheid population synthesis results. Results. In our search, out of an overall sample of more than 7200 Cepheids, we found 52 candidate Cepheid binary systems in the LMC (30 fundamental and 22 first-overtone mode) and 145 in the SMC (85 fundamental and 60 first-overtone mode). The majority of the sample is characterized by orbital periods of 2000–4000 d and eccentricities of 0.2–0.5. Moreover, we report two candidates in each galaxy with the Cepheid likely existing with a giant companion. The incidence rate ratio for SMC to LMC calculated from our sample is in agreement with binary Cepheid population synthesis predictions. Conclusions. In our attempt to quantify the non-evolutionary period change connected with the LTTE, our systematic search has enriched the Cepheid binary sample by a factor of about 2 in both galaxies. The future spectroscopic follow-up can confirm the binarity nature of our sample and constrain the orbital parameters.

Long-term monitoring of large-scale magnetic fields across optical and near-infrared domains with ESPaDOnS, Narval, and SPIRou

Context. Dynamo models describing the generation of stellar magnetic fields for partly and fully convective stars are guided by observational constraints. Zeeman-Doppler imaging has revealed a variety of magnetic field geometries and, for fully convective stars in particular, a dichotomy: either strong, mostly axisymmetric, and dipole-dominated or weak, non-axisymmetric, and multipole-dominated. This dichotomy is explained either by dynamo bistability (i.e., two coexisting and stable dynamo branches) or by long-term magnetic cycles with polarity reversals, but there is no definite conclusion on the matter. Aims. Our aim is to monitor the evolution of the large-scale field for a sample of nearby M dwarfs with masses between 0.1 and 0.6 M⊙, which is of prime interest to inform distinct dynamo theories and explain the variety of magnetic field geometries studied in previous works. This also has the potential to put long-term cyclic variations of the Sun’s magnetic field into a broader context. Methods. We analysed optical spectropolarimetric data sets collected with ESPaDOnS and Narval between 2005 and 2016, and near-infrared SPIRou data obtained between 2019 and 2022 for three well-studied, active M dwarfs: EV Lac, DS Leo, and CN Leo. We looked for secular changes in time series of longitudinal magnetic field, width of unpolarised mean-line profiles, and large-scale field topology as retrieved with principal component analysis and Zeeman-Doppler imaging. Results. We retrieved pulsating (EV Lac), stable (DS Leo), and sine-like (CN Leo) long-term trends in longitudinal field. The width of near-infrared mean-line profiles exhibits rotational modulation only for DS Leo, whereas in the optical it is evident for both EV Lac and DS Leo. The line width variations are not necessarily correlated to those of the longitudinal field, suggesting complex relations between small- and large-scale field. We also recorded topological changes in the form of a reduced axisymmetry for EV Lac and transition from a toroidal-dominated to poloidal-dominated regime for DS Leo. For CN Leo, the topology remained predominantly poloidal, dipolar, and axisymmetric, with only an oscillation in field strength. Conclusions. Our results show a peculiar evolution of the magnetic field for each M dwarf individually, with DS Leo and EV Lac manifesting more evident variations than CN Leo. These findings confirm that M dwarfs with distinct masses and rotation periods can undergo magnetic long-term variations and suggest an underlying variety of cyclic behaviours of their magnetic fields.