Secular Decrease Research Articles

OO Leo: An Active Contact Binary with Possible Solar-like Differential Rotation

With Transiting Exoplanet Survey Satellite (TESS) high-precision photometry and Large Sky Area Multi-object Fiber Spectroscopic Telescope medium-resolution spectra, we present the first light and radial velocity curve analyses for the eclipsing binary OO Leo. The simultaneous solution suggests that OO Leo is a W-subtype contact binary with a relatively low mass ratio (1/q = 0.173) and a moderate degree of contact (f = 28.1%). The asymmetry and continuous changes observed in the TESS light curve were properly modeled by one retrograde cool spot on its secondary surface. A detailed investigation of the Hα line also confirmed that the secondary star had a high level of magnetic activity. The retrograde longitudinal motion of the spot can be explained by a solar-like differential rotation in the secondary component. The orbital period investigation revealed that OO Leo is undergoing a secular decrease and a cyclic variation in its orbital period. The secular decrease may be mainly caused by mass transfer from the more massive secondary star to the less massive primary star. The cyclic period variation can be explained by the light–time effect of an invisible third body or the cyclic magnetic activity of the secondary star. The long-lived spot migration in the longitudinal direction makes OO Leo an excellent target for investigating the differential rotations of contact binaries.

The Dynamical State of the Didymos System before and after the DART Impact

NASA’s Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the natural satellite of (65803) Didymos, on 2022 September 26, as a first successful test of kinetic impactor technology for deflecting a potentially hazardous object in space. The experiment resulted in a small change to the dynamical state of the Didymos system consistent with expectations and Level 1 mission requirements. In the preencounter paper, predictions were put forward regarding the pre- and postimpact dynamical state of the Didymos system. Here we assess these predictions, update preliminary findings published after the impact, report on new findings related to dynamics, and provide implications for ESA’s Hera mission to Didymos, scheduled for launch in 2024 October with arrival in 2026 December. Preencounter predictions tested to date are largely in line with observations, despite the unexpected, flattened appearance of Didymos compared to the radar model and the apparent preimpact oblate shape of Dimorphos (with implications for the origin of the system that remain under investigation). New findings include that Dimorphos likely became prolate due to the impact and may have entered a tumbling rotation state. A possible detection of a postimpact transient secular decrease in the binary orbital period suggests possible dynamical coupling with persistent ejecta. Timescales for damping of any tumbling and clearing of any debris are uncertain. The largest uncertainty in the momentum transfer enhancement factor of the DART impact remains the mass of Dimorphos, which will be resolved by the Hera mission.

V0405 Dra: A New Deep and Low Mass Ratio Contact Binary with Extremely Fast Decrease in the Orbital Period

V0405 Dra is a W UMa-type binary star. Based on the TESS data, we have conducted an orbital period study and performed a light curve analysis for the system. The orbital period study reveals that the O − C curve for V0405 Dra exhibits secular decrease at an extremely high rate of dP/dt = −2.71 × 10−6 day year−1, along with periodic variations characterized by an amplitude of A 3 = 0.0032 day and a period of P 3 = 1.413 years. The orbital periodic change is possibly due to the light-travel time effect resulting from an additional third body in the system, for which we estimate a minimum mass of M 3 = 0.77M ⊙. By employing the 2013 version of the Wilson-Devinney (W-D) method to synthesize a light curve, we derived photometric solutions indicating that V0405 Dra is a new deep (f = 68.7%) and low-mass ratio (q = 0.175) contact binary. The fast decrease in its orbital period is likely caused by mass transfer from the more massive primary star to the less massive secondary star, or due to angular momentum loss. With further mass transfer and loss of angular momentum, the binary will gradually evolve into a tighter contact configuration, eventually leading to a merger into a single star, following the evolutionary paths suggested for such deep and low mass ratio contact binaries.

Simultaneous Photometric and Spectroscopic Analysis of V505 Lacertae, a Photospherically and Chromospherically Active Contact Binary Star

New BVR photometric and high-resolution spectroscopic observations of V505 Lac are presented with Transiting Exoplanet Survey Satellite (TESS) photometric data. The orbital period has experienced a secular decrease during the past 16 yr. A clear anticorrelation in the primary and secondary eclipse timing variation (PSETV) obtained from the TESS data is also identified. A double-lined radial velocity (RV) curve is secured, and the effective temperatures of the less- and more-massive stars (Stars 1 and 2, respectively) are measured. Using a spectral subtraction technique, excess emissions are detected in the time-series Ca ii H and K and Hα lines for Star 2. Simultaneous analysis of the light and RV curves using the Wilson–Devinney (WD) code reveals that V505 Lac is a photospherically and chromospherically active W-subtype contact binary system. The component-star masses and radii are determined to an accuracy of approximately 1%. The WD spot model is individually applied to 221 light curves segmented from the TESS data so as to derive the spot parameters of a cool spot on Star 2. The combined variations in both longitude and colatitude among the spot parameters appear to be strongly associated with those of both the anticorrelation in the PSETV and the O’Connell effect in the TESS light curves. Robust negative linear relationships between the PSETV anticorrelation size and the O’Connell effect magnitude are found for the first time. Mass–radius, mass–luminosity, and mass ratio–mass diagrams of contact binaries, along with the mass ratio frequency distribution, are presented in an attempt to elucidate the evolutionary characteristics of these systems.

Prevalence of Gastric Precursor Lesions in Countries With Differential Gastric Cancer Burden: A Systematic Review and Meta-analysis

The prevalence of precursor lesions for gastric cancer (GC) and the differential burden between countries of varying GC risk is not well-understood. We conducted a systematic review and meta-analysis to estimate the global prevalence of precursor lesions. We estimated the prevalence of atrophic gastritis (AG), gastric intestinal metaplasia (IM), and dysplasia in regions with low, medium, and high GC incidence. Because IM is an advanced manifestation of AG, we assessed the prevalence of less advanced precursors, regardless of the presence of more advanced lesions. Prevalence was sub-stratified by Helicobacter pylori infection, symptomatology, and period (<2000, 2000-2010, and >2010). Among the 582 articles that underwent full-text review, 166 studies met inclusion criteria. The global prevalence estimates of AG, IM, and dysplasia were 25.4%, 16.2%, and 2.0%, respectively, on the basis of 126 studies that reported the prevalence of less advanced precursors, regardless of the presence of more advanced lesions. The prevalence of all precursor lesions was higher in high and medium compared with low GC incidence countries (P < .01). Prevalence of AG and IM was significantly higher among H pylori-infected individuals (P < .01) but not statistically different between symptomatic and asymptomatic individuals (P > .17). All precursors demonstrated a secular decrease in prevalence over time. Gastric precursor lesions have differences in prevalence in regions with differential GC incidence and are associated with H pylori infection. Because of the substantial prevalence of precursor lesions in both symptomatic and asymptomatic individuals, symptomatic evaluation may not be sufficient to identify individuals at risk. These estimates provide important insights for tailoring GC prevention strategies.

Extremely Early Appearance of Islet Autoantibodies in Genetically Susceptible Children

Objective. We studied the characteristics of children who developed islet autoantibodies by the age of 0.50 years and hypothesized that the appearance of extremely early islet autoimmunity differs between four birth cohorts within 1994–2019 according to the change in the incidence of Type 1 diabetes (T1D) in Finland. Methods. Data from Finnish children participating in the Type 1 Diabetes Prediction and Prevention (DIPP) study, or the Environmental Determinants of Diabetes in the Young (TEDDY) study were analyzed. These studies follow children with increased HLA-conferred risk for T1D with regular measurements of islet autoantibodies. Maternally transferred antibodies were excluded by comparing islet autoantibodies in cord serum, child’s first follow-up serum and the maternal serum. Results. Among 20,979 Finnish children at increased risk to T1D, 53 (0.25%) developed at least one islet autoantibody at the age of ≤0.50 years. During a mean follow-up of 8.1 years, 15.1% progressed to T1D (median age at diagnosis 2.0 years), 43.4% developed confirmed islet autoimmunity but no T1D, and 41.5% had only transient islet autoantibodies. IAA was the most common first-appearing autoantibody. Among progressors, age at diagnosis was 1.0–2.4 years in children with IAA-initiated autoimmunity and 4.5–16.1 years in ZnT8A-initiated autoimmunity. When comparing children developing autoantibodies either at the age of ≤0.50 years or 0.51–0.75 years, confirmed positivity during follow-up was more common in the older group (81.7% vs. 58.5%; p = 0.002 ). In four birth cohorts within 1994–2019 appearance of islet autoantibodies at the age of ≤0.50 years decreased towards the most recent birth cohorts ( p = 0.016 ). Conclusion. Islet autoimmunity by the age of 0.50 years was rare in genetically susceptible children and was typically initiated with IAA. Confirmed positivity was less common in children with autoantibodies at age ≤0.50 than at slightly older age. The secular decrease of islet autoimmunity before age 0.50 years was observed. This trial is registered with NCT03269084 and NCT00279318.

Magnetic activity on two contact binaries: VW Boo and V1128 Tau from TESS data

Using the continuous TESS data, we found small intrinsic variations in the light curves of VW Boo and V1128 Tau. We selected five sets of light curves and derived the photometric solutions by using the Wilson-Devinney code. The results indicate that the intrinsic light curve variations in VW Boo are attributed to the evolution of a cool spot. In the case of V1128 Tau, the disappearance or reappearance of a cool spot might account for the variation in three sets of light curves. The obtained solutions also reveal that these two systems are W-type shallow-contact binaries (f≤15%). Period analyses for these two systems were carried out based on all available times of minimum. The period analysis of VW Boo shows that its period is decreasing at a rate of dP/dt=−1.52×10−7d yr−1, together with a cyclic oscillation with a period of 27.17 yr and a semi-amplitude of 0.0063 d. Similarly, the orbital period of V1128 Tau also shows a secular decrease (dP/dt=−1.40×10−7d yr−1), accompanied by a cyclic oscillation (P3= 16.11 yr and K3=0.0011 d). The secular decrease might be caused by mass transfer, while the cyclic oscillation might result from the presence of a third body or magnetic activity.

Orbital Period Variations in HT Cas: Evidence for Additional Angular Momentum Loss and a High-eccentricity Giant Planet

We present a timing study of the short-period eclipsing cataclysmic variable (CV) HT Cas. Based on new eclipse times derived from our photometric monitoring and archival optical data, combined with historical timings, spanning ∼42 yr, we detect a secular decrease in the orbital period at a rate of and a cyclic period wiggle with an amplitude of 79.3 s and a period of 30.28 yr. We find that neither gravitational radiation nor magnetic braking can explain the observed decrease rate, suggesting the presence of additional angular momentum loss (AML). The empirical consequential AML (eCAML) model developed by Schreiber et al. can well match the observed orbital decay in HT Cas, and the physical mechanism for eCAML is most likely attributable to the frictional AML following nova eruptions. As for the cyclic variation, the best explanation is the influence of an unseen companion in orbit around the binary. The derived orbital parameters reveal that the hypothetical third body could be a giant planet with mass of M 3 ≃ 14M Jup that is moving on a highly eccentric orbit (e = 0.82). Taken together the results of the present study suggest that HT Cas is a unique triple system containing a high-eccentricity giant planet and it has the potential to become an ideal laboratory in which to test models of CV evolution.

Photometric and Period Variation study of two contact binaries ASAS J034931-0431.2 and KIC 11413213

We present the first photometric analysis of ASAS J034931-0431.2 and KIC 11413213, two short-period eclipsing contact binaries. Photometric analysis using the Wilson–Devinney method was performed using TESS, Kepler 2, and Gaia DR3 data available. Based on the collected times of minima, period variation studies were carried out and the orbital period was found to show a secular period decrease in both the variables. This can be inferred due to mass transfer or Angular momentum loss in the systems and the same are discussed. From the results obtained, ASAS J034931-0431.2 is an A-type marginal contact binary system with a low mass-ratio of q ∼ 0.2, while KIC 11413213 is W-type marginal contact with a high mass-ratio of q ∼ 1.2. The evolutionary status of the variables in the study is discussed using the Mass-Radius diagram, the long-time period decrease, the marginal-contact configuration, and the astrophysical parameters of these systems.

The Secular Decrease in UK Safe Asset Market Power

We document the decline in market power of the U.K. in safe assets and quantify the resulting losses. We estimate an increasing elasticity of demand for U.K. public debt during the latter half of the 20th century. This is in sharp contrast to the U.S., which displays the opposite pattern with decreasing elasticities of demand during this time. We argue that the decline in market power of the U.K. in safe assets resulted in a sizable decline in seigniorage revenues.

V2769 Orionis: A new low-mass-ratio and deep-contact binary

We carried out the first multi-color light curves analysis of the eclipsing binary V2769 Ori. The photometric solution was determined by applying the Wilson–Devinney method. The results show that V2769 Ori is a deep, low-mass-ratio contact binary with a mass ratio of q=0.162(±0.003) and a contact degree of f=55(±8)%. The total eclipse characteristics of V2769 Ori imply that the photometric solution we obtained is reliable. With all available light minimum times, the O–C diagram was constructed and analyzed. The orbital period analysis reveals a long-term period decrease at a rate of dP/dt=−1.24(±0.08)×10−6dyr−1 and a periodic oscillation with a period of 8.77(±0.15) years. The secular period decrease can be explained by a combination of mass transfer between the two components and the angular momentum loss of the system. As the orbital period decrease, the shrinking of the inner and outer critical Roche lobes causes an increase in contact degree, and the binary system will finally merge into a rapidly rotating single star. Periodic oscillation may be the result of the light-travel time effect due to the presence of an unseen component.

Secular decrease in chromosomal mosaicism in cultured and uncultured peripheral blood cells of six patients with mosaic Down syndrome.

As noted in a review paper,1 a large-scale study revealed that approximately 1.1%–3.8% of all children with Down syndrome (DS) are born with mosaic DS.2, 3 DS is diagnosed postnatally by chromosome G-banding analysis of peripheral blood cultures, and most patients do not undergo subsequent repeat analysis. We present secular changes in the mosaic ratio of six patients with mosaic DS. The G-banding, chromosome 21 fluorescence in situ hybridization (chr21 FISH) from peripheral blood cultures and the chr21 FISH analysis of uncultured blood cells showed a drastic reduction in the mosaic ratio in five patients aged between 7 and 23 years. The mosaic ratio of a child aged 3 years and 3 months gradually, but not drastically, decreased over time. However, no decrease in the mosaic ratio was seen in the buccal mucosa or fibroblasts by chr21 FISH in any mosaic patient. Low-invasive chromosomal analyses of 100 cells per patient from different tissues were performed by SRL, Inc. The analyses were as follows (Table 1). (1) T lymphocyte chromosome analyses of cultured peripheral blood samples by PHA (phytohemagglutinin) stimulation, including (1-a) G-banding and (1-b) chr21 FISH analysis using chromosome 21q22.13-q22.2 probes (Vysis, Abbott Molecular); (2) chr21 FISH analysis of uncultured blood cells, including various leukocytes, instead of bone marrow puncture; (3) chr21 FISH analysis of epithelial cells from the buccal mucosa; and (4) chr21 FISH analysis of fibroblasts cultured from a tooth extraction. The six patients (A–F) with mosaic DS (five females and one male) were aged from 3 years and 3 months to 23 years (Table 1). Five patients (B–F) aged between 7 and 23 years showed drastically decreased mosaic ratios (1%–8%) by G-banding, and FISH analysis of the peripheral blood culture and of uncultured blood cells compared with the postnatal result (Table 1, the red font). Patient A showed a gradual decrease in mosaicism on G-banding and FISH of the peripheral blood culture and by FISH analysis of uncultured blood cells at 11 months, 2 years and 9 months, and 3 years and 3 months of age compared with the postnatal result (Table 1, the red font). However, none of the six patients showed a decreased mosaic ratio in the buccal mucosa analysis or tooth-extraction-derived-fibroblast FISH analysis. Previously, two reports documented a decreased mosaic ratio in mosaic DS patients during early childhood, mainly in peripheral blood cultures.4, 5 We studied longitudinal changes in the mosaic ratio of six mosaic DS patients, including young adults. No decrease was observed in the epithelial cells of the buccal mucosa or cultured fibroblasts. The observed secular decrease in the mosaic ratio in cultured and uncultured peripheral blood cells did not appear to be a mechanism of trisomy rescue because six adult patients with standard trisomy 21 and one patient with translocated trisomy 21 showed no decrease in trisomy cell number in cultured and uncultured peripheral blood cells over time (Table S1, the green font). Within the bone marrow, hematopoietic stem cells exist in a hypoxic microenvironment (niche) and are in a quiescent (G0), undifferentiated state.6 In this microenvironment, trisomy cells are considered more detrimental to viability than normal cells, which may explain the secular decrease in chromosomal mosaicism with mosaic DS in this study. Permission has been obtained from the patients' mothers for the participation in this study. Financial support was provided by JSPS KAKENHI (Grant number: JP18K02497). The authors declare no conflict of interest. This study has received ethical approval from Tokyo Kasei University Ethics Committee (Ita h-29-5) and the Tokyo Metropolitan Tobu Medical Center for Children with Developmental Disabilities Ethics Committee (29MoriTobuCe256-1). TABLE S1. Chromosomal analyses of the trisomy ratio of eight patients, seven with standard trisomy 21 and one translocated trisomy 21 (patient H). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

WISE J185503.7+592234: A particularly low mass ratio contact binary approaching merger

ABSTRACT In this paper, the total eclipsing binary WISE J185503.7+592234 (hereinafter J185503), whose mass ratio is around the mass ratio limit, was observed and investigated for the first time. The stellar atmospheric parameters of the primary (more massive) component were calculated by the spectral fitting, and the following results are obtained: Teff = 5747 ± 25 K, [Fe/H] = −0.16 ± 0.04 dex, logg = 4.78 ± 0.05 cm s−2. Although J185503 has a very small amplitude (∼ 0.17 mag in V band) and a short period (0.2800782 d), its light curves exhibit total eclipses (eclipse duration: ∼ 40 min, which is about 0.1 phase). The light curves derived from TESS exhibit some unusual behaviour, such as inversion of the O’Connell effect, exchange of occultation, and transit depths. Photometric solutions obtained from the multiband observations suggest that J185503 has a particularly low mass ratio (q = 0.0514) and a moderate contact degree of $26{{\ \rm per\ cent}}$. Based on 103 newly determined times of minimum spanning 14 yr, a secular period decrease was found, which is calculated to be dP/dt = −2.24 × 10−7 d yr−1. Through analysing the instability criterion, such as the instability separation, the instability mass ratio, and the ratio of spin angular momentum (Jspin) to the orbital angular momentum (Jorb), J185503 can be regarded as a progenitor of luminous red novae.

The First Photometric and Spectroscopic Study of Contact Binary V2840 Cygni

The first photometric, spectroscopic and period variation studies of neglected short-period eclipsing binary V2840 Cygni are presented. High mass ratio contact binaries (HMRCBs), especially those in the weak-contact configuration, are vital when probing the evolutionary models of contact binaries (CBs) using stellar parameters. The photometric solutions reveal the weak-contact nature of V2840 Cygni with a high mass ratio (∼1.36), motivating us to investigate the nature of such binaries. The period variation study of V2840 Cygni spanning 15 yr shows a secular period decrease at a rate of ∼5.5 × 10−7 day yr−1, indicating mass transfer between the components. The superimposed cyclic variation provides a basic understanding of the possible third body (P 3 ∼ 8 yr, m 3 ∼ 0.51 M ⊙). Following the derived parameters, the evolution of the system is discussed based on the thermal relaxation oscillation (TRO) model. It is found that V2840 Cygni falls in a special category of HMRCBs, which validates TRO. To characterize the nature of HMRCBs, a catalog of 59 CBs with high mass ratios has been compiled along with their derived parameters from the literature. For all the HMRCBs in the study, a possible correlation between their contact configuration and observed period variations for relative log J rel is discussed. The spectroscopic study of V2840 Cygni provides evidence of the presence of magnetic activity in the system and the existence of ongoing mass transfer which is additionally deduced from the period variation study. The LAMOST spectra of 17 HMRCBs are collected to interpret the stellar magnetic activity in such systems.

Why supercontinents became shorter lived as the Earth evolved

Periodic assembly and break-up of supercontinents since at least two billion years ago (Ga), dubbed the supercontinent cycle, provides the first-order tectonic control on the evolution of the Earth System including episodic orogenic events, mineralization, the formation and closure of oceans and superoceans, and even the evolution of life. However, the lifespan of the supercontinents appears to decrease with time, from ∼300 million years (Myr) for Nuna/Columbia, to 200–250 Myr for Rodinia and ∼150 Myr for the youngest supercontinent Pangaea. To understand what caused such a secular decrease in supercontinental lifespan, we conduct 3-D geodynamic modeling using realistic tectonic settings. The results show that the yield stress of newly formed orogens during the assembly of a supercontinent provides the dominant control on the lifespan of the supercontinent, implying that the yield stress of young orogens becomes lower with time. We hypothesize that the decreasing mantle temperature due to Earth’s secular cooling might have caused new orogens to become weaker.

Secular changes of foot dimensions among children and adolescents (3-18 years of age).

The purpose of this study was to assess the changes in the foot dimensions in children and adolescents (3-18 years of age) from Krakow (Poland), between the years 2010 and 2020. The examined group of children and adolescents (3-18-year olds) took part in two cross-sectional surveys carried out in 2010 and 2020. The cohort examined in 2010 consisted of 1,989 females and 1,893 males and the 2020 series included 1,702 females and 1,584 males. Body height (B-v), length of the lower limbs (B-sy) foot length (pte-ap) and breadth (mtt-mtf) were measured. The last two measurements were the basis for calculating the foot index and estimated area of the foot. Generally, children examined in 2020 had relatively wider feet in proportion to their length compared to their peers from the 2010 cohort. This change was mirrored by secular trends regarding the estimated area of the foot. Additionally, a secular decrease of the length of the foot was compensated by the increasing width of this segment of the body, which among girls occurred especially after 10 years of age. The present study provides new information regarding secular changes in foot proportions among Polish children and adolescents. Results obtained in this stud are additionally significant, as there is no similar research concerning the population of Poland.

The Secular Decrease in UK Safe Asset Market Power

The Secular Decrease in UK Safe Asset Market Power

Trace metals in saline waters and brines from China: Implications for tectonic and climatic controls on basin-related mineralization

• Surficial metal-bearing brines can be regarded as the initial ore-forming fluids of basin-related mineral deposits . • Climate is the link between major tectonic events and global/large-scale basin-related mineralization . Research into mineralization using a deposit-centric approach has identified three principal factors (evolution of the hydrosphere–atmosphere, secular decrease in global heat production, and long-term global tectonic trends) that have influenced the global pattern of metallogenesis. However, these factors do not explain the peak occurrences of basin-related mineralization during particular periods of Earth’s evolution. Here we shift the research perspective from an ore-deposit-centric approach to one focusing on the formation processes of ore-forming fluids by using mass spectrometry to analyze the concentrations of metallic elements (U, Cr, Fe, Mn, Co, Ni, Cu, Mo, Cd, Sn, Pb, Zn, and V) of naturally occurring saline water bodies (brines) in currently developing basins in China. Our aim is to determine the presence of metal-bearing fluids and establish the formation processes of ore-forming fluids that can subsequently generate mineral deposits. The concentrations of trace metals in evaporated seawater and surficial saline waters (brines) in continental basins can reach up to mg/L level, with the increase in salinity resulting from the significant evaporation that occurs in semi-arid to arid environments. The high salinities increase the density of metal-bearing brines, which in turn causes these brines to circulate and mix with groundwater, resulting in enriched metal element concentrations in the groundwater. Groundwater containing dissolved evaporites also shows relatively high concentrations of metal elements (up to mg/L level) that compare with fresh groundwater. These metal-bearing brines can be regarded as the initial ore-forming fluids of basin-related mineral deposits, such as unconformity-type U deposits, red-bed Cu deposits, and some stratiform Pb–Zn deposits. The metal-bearing brines are the result of substantial evaporation under arid to semi-arid climates. Therefore, we conclude that climate is an important control on the formation of basin-related mineralization and that the tectonoclimatic setting plays an essential role in the formation of metal-bearing brines in closed inland basins. The major climatic events, such as the snowball and greenhouse event can affect the basin-related mineralization globally. The super mantle plume event could affect the global basin-related mineralization by changing the global climate significantly.

Enhanced continental chemical weathering during the multiple early Eocene hyperthermals: New constraints from the southern Indian Ocean

Multiple short-term (<105 years) global warming events (“hyperthermals”) occurred throughout the early Eocene. Chemical weathering of continental silicate rocks is considered to have played a key role in recovery from these transient global warming events via consumption of excess atmospheric CO2. However, although evidence of this negative feedback has been reported for the Paleocene–Eocene Thermal Maximum (PETM), the effectiveness of chemical weathering during other transient hyperthermals remains poorly constrained. Here, we newly report early Eocene marine Os isotope records including Eocene Thermal Maximum 2 (ETM2), the I1 event, and ETM3 at Ocean Drilling Program Site 752 in the southern Indian Ocean. We demonstrate that marine 187Os/188Os increased during the hyperthermal events that were less severe than the PETM. The intensity of continental silicate weathering increased by 18%–22%, 17%–21%, and 13%–16% during ETM2, the I1 event, and ETM3, respectively, compared to the background conditions. Based on a reconsidered formulation of an Os mass-balance model, the intensity of continental silicate weathering during the PETM was reassessed to be a 34%–42% increase relative to the pre-PETM level. Thus, the continental chemical weathering flux during the Eocene hyperthermals may have been up to half as large as that of the PETM. It is noteworthy that the ordering of the changes in continental silicate weathering did not agree with the ordering of the seawater temperature rise among these events. This weathering–warming inconsistency might be attributable to (1) potential underestimation of continental silicate weathering due to the emplacement of Large Igneous Provinces (LIPs) and related basalt weathering, such as the North Atlantic Igneous Province and Siletzia in western North America, (2) changes in the background level of weathering intensity, and/or (3) a secular decrease in continental weatherability through the long-lasting early Eocene warming trend.

Secular changes in the waist, hips circumferences and selected associated indicators, among preschool children from Kraków (Poland), between 1983 and 2018

Waist circumference and derived indicators are great for measuring the risk of abdominal obesity. The main aim of the study was to assess the changes in the waist, hips circumferences and selected associated indicators, among preschool children (3-7years of age) from Kraków, Poland, between 1983, 2008 and 2018. The research was conducted in randomly selected kindergarten in Krakow (Poland). The 1983 cohort consisted of 1414 children and the 2008 and 2018 series included 1050 preschoolers each. Analyzed characteristics included waist and hip circumferences, body height, waist-to-hips ratio (WHR) and waist-to-height ratio (WHtR). There was a negative secular trend regarding circumferences of the hips and waist, as well as WHtR. In girls, WHR was, the greatest in the 2018 cohort, while among boys there was a secular increase in the value of this parameter compared to the 2008 cohort, but not to the 1983 series. The coexistence of currently noted trends with the previously described secular decrease in the prevalence of overweight/obesity and increase in trunk adiposity in the same population, suggests that WHR is preferable to body mass index in assessing the risk associated with excess adiposity in the population examined in the presented study.