Secular Variability Research Articles

Coupled Disk-star Evolution in Galactic Nuclei and the Lifetimes of QPE Sources

A modest fraction of the stars in galactic nuclei fed toward the central supermassive black hole (SMBH) approach on low-eccentricity orbits driven by gravitational-wave radiation (extreme mass ratio inspiral (EMRI)). In the likely event that a gaseous accretion disk is created in the nucleus during this slow inspiral (e.g., via an independent tidal disruption event (TDE)), star–disk collisions generate regular short-lived flares consistent with the observed quasiperiodic eruption (QPE) sources. We present a model for the coupled star-disk evolution, which self-consistently accounts for mass and thermal energy injected into the disk from stellar collisions and associated mass ablation. For weak collision/ablation heating, the disk is thermally unstable and undergoes limit-cycle oscillations, which modulate its properties and lead to accretion-powered outbursts on timescales of years to decades, with a time-averaged accretion rate ∼0.1Ṁ Edd. Stronger collision/ablation heating acts to stabilize the disk, enabling roughly steady accretion at the EMRI-stripping rate. In either case, the stellar destruction time through ablation, and hence the maximum QPE lifetime, is ∼102–103 yr, far longer than fallback accretion after a TDE. The quiescent accretion disks in QPE sources may at the present epoch be self-sustaining and fed primarily by EMRI ablation. Indeed, the observed range of secular variability broadly matches those predicted for collision-fed disks. Changes in the QPE recurrence pattern following such outbursts, similar to that observed in GSN 069, could arise from temporary misalignment between the EMRI-fed disk and the SMBH equatorial plane as the former regrows its mass after a state transition.

Submillimeter and Mid-Infrared Variability of Young Stellar Objects in the M17SWex Intermediate-mass Star-forming Region

We present a comprehensive analysis of young stellar object (YSO) variability within the M17 Southwest Extension (M17 SWex), using 3.5 yr of monitoring data from the James Clerk Maxwell Telescope (JCMT) Transient Survey at submillimeter and 9 yr from the NEOWISE mission at mid-infrared (mid-IR). Our study encompasses observations of 147 bright submillimeter peaks identified within our deep JCMT coadded map as well as 156 YSOs in NEOWISE W1 and 179 in W2 that were previously identified in Spitzer surveys. We find three robust submillimeter variables: two are candidate YSOs and one is a likely extragalactic source. At mid-IR wavelengths, our analysis reveals secular and stochastic variability in 47 YSOs, with the highest fraction of secular variability occurring at the earliest evolutionary stage. This is similar to what has previously been observed for low-mass YSO variability within the Gould Belt. However, we observe less overall variability in M17 SWex at both the submillimeter and mid-IR. We suspect that this lower fraction is due to the greater distance to M17 SWex. Our findings showcase the utility of multiwavelength observations to better capture the complex variability phenomena inherent to star formation processes and demonstrate the importance of years-long monitoring of a diverse selection of star-forming environments.

NEW APPROACH TOWARDS THE PROBLEM OF SOMATIC CRITERIA OF SECULAR TRENDS. SEXUAL SOMATIC DIMORPHISM

Introduction. The goal of study is description of secular dynamics of sex dimorphism (SD) of height, weight, chest girth of children aged 9 years and teenagers 13 years old from Russia and neighboring countries through 1920–2010. Materials and methods. The main source of data — materials of books on physical development of children and adolescents from cities and rural regions of Russia and USSR, collected and processed according to the universal methodical standards of Research Institute of Hygiene of children and adolescents. The quantitative estimation of SD value was held using Kullback divergence. One-year age groups, contrastive in biological essence, are under discussion. The estimation of the vector and level of associations of SD of anthropometric traits and secular factor was held using correlation analysis. The analysis of local patterns of secular SD dynamics of separate traits was carried out. Results. Secular variability of height and weight SD of 9-year-old children is not significant. While secular dynamics of three body dimensions of 13-year-old teenagers is significant, the highest determination coefficient is fixed for weight. For Moscow samples the decrease of height and weight SD is fixed through the historic interval 1960s – 70s with the following recovery up to the level of 1920s in 2000s. Temporal dynamics of SD of 9-year-old children of St. Petersburg through the interval 1960s – 2000s consists of macrosomization of girls; the tendency for 13-year-old teenagers is opposite. Temporal dynamics of somatic SD of 9-year-old Russian children of Kazan reveals stability through the interval 1960th-1990th; for 13-year-old teenagers’ parameters of transversal body development demonstrate secular stability, as to height – boys compensate their lag compared to girls. For Kirovsk city (Murmansk region) through the interval 1950s – 1970s temporal fluctuations of height and weight SD of 9-year-old children are less than 0,2 standard deviations; height and weight SD of 13-year-old teenagers reveal temporal increase (0,4–0,6 standard deviations). Conclusion. The results confirm the importance of somatic SD as the criterion of secular dynamics for 13-year-old teenagers and witness, as a whole, to the temporal stability of SD during second childhood (9 years). Local differences do not contribute significantly to the intensity of secular dynamics of SD. The process of secular macrosomization of one sex as compared to the other is not the exclusive prerogative of boys and male teenagers.

Sample and Statistical Analysis on NEOWISE Variability of ATLASGAL Sources

This study focuses on the analysis of mid-infrared variability in a sample of high-mass young stellar objects (YSOs) associated with the cataloged sources from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). The Near-Earth Object Wide-field Infrared Survey Explorer Reactivation Mission (NEOWISE) database was used to explore the long-term mid-infrared variability of these high-mass YSOs at a half-year scale. After matching with NEOWISE photometric measurements, a total of 2230 ATLASGAL sources were selected for the variability analysis, out of which 717 were identified as variables. The derived proportions of variables at different evolutionary stages show that the variability rate of high-mass YSOs is highest during the YSO stage and decreases with evolution toward the H ii region stage, resembling the behavior of low-mass YSOs. The variables can be classified into six types based on their light curves, divided into two categories: secular (linear, sin, sin+linear) and stochastic variables (burst, drop, and irregular). The magnitude–color variations observed in ∼160 secular variables can be mainly divided into “bluer when brighter/redder when dimming” and “redder when brighter/bluer when dimming,” likely originating from changes in accretion rate or the effect of extinction due to obscuration. Moreover, several episodic accretion candidates were selected for further observational studies.

The influence of small bipolar magnetic regions on basic solar quantities

Understanding the evolution of the solar magnetic field is of great importance for heliosphere, dynamo, and irradiance studies, for example. While the contribution of the field in active regions (ARs) hosting sunspots to the Sun's large-scale field has been extensively modelled, we still lack a realistic model of the contribution of smaller-scale magnetic regions such as ephemeral regions which do not contain any sunspots. For this work, we studied the effect of small and large bipolar magnetic regions (BMRs) on the large-scale solar magnetic field. The evolution of the total and open magnetic flux, the polar fields, and the toroidal flux loss since 1874 has been simulated with a surface flux transport model (SFTM) and the results were compared to analytical considerations and observational data. For this purpose, we constructed semi-synthetic BMR records using the international sunspot number as a proxy. We calculated the emergence rate of all BMRs from a single power-law size distribution, whose exponent varies with solar activity. The spatial distribution of the BMRs was calculated from statistical relationships derived from various solar observations. We included BMRs with a magnetic flux as low as $2 $ Mx in our SFTM, corresponding to regions with lifetimes down to one day. We found a good agreement between the computed total magnetic flux and observations, even though we do not have a free parameter to adjust the simulated total flux to observations, as in earlier versions of the employed SFTM. The open flux, the polar fields, and the toroidal flux loss are also consistent with observations and independent reconstructions. In our model, small BMRs contribute about one-third of the total and open flux at activity maximum, while their contribution increases to roughly half at activity minimum. An even greater impact is found on the polar fields and the toroidal flux loss, for which the contribution of small BMRs is comparable to that of spot-containing ARs at all activity levels. Even so, smaller regions, not included in our simulations, do not seem to play a significant role due to their high tilt angle scatter. Our simulation results suggest that most of the statistical noise is caused by large ARs, while small BMRs have a stabilising effect on the magnetic flux evolution, especially for the polar field reversals. We conclude that small BMRs (here, with magnetic fluxes between $2 $ Mx and $3 $ Mx) may also play an important role in the evolution of the solar magnetic field at large spatial scales. Their impact is largest at low solar activity, but it is also substantial during activity maxima, although the actual relative contributions by small and large regions depend on the steepness of their emergence rate distribution. The inclusion of small BMRs in SFTM simulations will allow the secular variability in solar irradiance to be better constrained and the generation of the poloidal field in the Babcock-Leighton dynamo to be better understood.

Empirical assessment of the role of the Sun in climate change using balanced multi-proxy solar records

The role of the Sun in climate change is hotly debated. Some studies suggest its impact is significant, while others suggest it is minimal. The Intergovernmental Panel on Climate Change (IPCC) supports the latter view and suggests that nearly 100% of the observed surface warming from 1850–1900 to 2020 is due to anthropogenic emissions. However, the IPCC’s conclusions are based solely on computer simulations made with global climate models (GCMs) forced with a total solar irradiance (TSI) record showing a low multi-decadal and secular variability. The same models also assume that the Sun affects the climate system only through radiative forcing – such as TSI – even though the climate could also be affected by other solar processes. In this paper I propose three “balanced” multi-proxy models of total solar activity (TSA) that consider all main solar proxies proposed in scientific literature. Their optimal signature on global and sea surface temperature records is assessed together with those produced by the anthropogenic and volcanic radiative forcing functions adopted by the CMIP6 GCMs. This is done by using a basic energy balance model calibrated with a differential multi-linear regression methodology, which allows the climate system to respond to the solar input differently than to radiative forcings alone, and to evaluate the climate’s characteristic time-response as well. The proposed methodology reproduces the results of the CMIP6 GCMs when their original forcing functions are applied under similar physical conditions, indicating that, in such a scenario, the likely range of the equilibrium climate sensitivity (ECS) could be 1.4 °C to 2.8 °C, with a mean of 2.1 °C (using the HadCRUT5 temperature record), which is compatible with the low-ECS CMIP6 GCM group. However, if the proposed solar records are used as TSA proxies and the climatic sensitivity to them is allowed to differ from the climatic sensitivity to radiative forcings, a much greater solar impact on climate change is found, along with a significantly reduced radiative effect. In this case, the ECS is found to be 0.9–1.8 °C, with a mean of around 1.3 °C. Lower ECS ranges (up to 20%) are found using HadSST4, HadCRUT4, and HadSST3. The result also suggests that at least about 80% of the solar influence on the climate may not be induced by TSI forcing alone, but rather by other Sun-climate processes (e.g., by a solar magnetic modulation of cosmic ray and other particle fluxes, and/or others), which must be thoroughly investigated and physically understood before trustworthy GCMs can be created. This result explains why empirical studies often found that the solar contribution to climate changes throughout the Holocene has been significant, whereas GCM-based studies, which only adopt radiative forcings, suggest that the Sun plays a relatively modest role.

Photometric and spectroscopic monitoring of YSOs in nearby star-forming regions – I. Eruptive YSOs

ABSTRACTMid-infrared (mid-IR) variability in young stellar objects (YSOs) is driven by several physical mechanisms, which produce a variety of amplitudes and light-curve shapes. One of these mechanisms, variable disc accretion, is predicted by models of episodic accretion to drive secular variability, including in the mid-IR. Because the largest accretion bursts are rare, adding new objects to the YSO eruptive variable class aids our understanding of the episodic accretion phenomenon and its possible impact on stellar and planetary formation. A previous analysis of 6.5 yr of NeoWISE light curves (3–5 μm) of ∼7000 nearby YSOs found an increase in the fraction of variability and variability amplitude for objects at younger stages of evolution. To help interpret these light curves, we have obtained low- and high-resolution near-IR spectra of 78 objects from this sample of YSOs. In this work, we present the analysis of nine nearby YSOs (d<1 kpc) that show the characteristics of known classes of eruptive variable YSOs. We find one FU Orionis (FUor)-like source, one EX Lupi type object, and six YSOs with mixed characteristics or V1647 Ori like objects. The varied characteristics observed in our sample are consistent with recent discoveries of eruptive YSOs. We discuss how a wide range in YSO outburst parameters (central mass, maximum accretion rate during outburst, evolutionary stage, and/or instability leading to the outburst) may play a significant role in the observed spectrophotometric properties of YSO outbursts.

Sample and Statistical Analysis of the Near-Earth Object Wide-field Infrared Survey Explorer Variability of the 6.7 GHz Methanol Maser Sources

We present a statistical study of infrared variability using the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) database for a sample consisting of 1085 high-mass young stellar objects (YSOs) related to 6.7 GHz methanol masers. A total of 383 maser sources were identified as NEOWISE variables and classified in two variability behavior classifications: 204 secular (linear, curved, and periodic) and 179 stochastic (burst, drop, and irregular) variables. Statistical analysis of the properties of these variables (e.g., the dust temperature, bolometric luminosity, hydrogen column density, W4 luminosity, and W1−W2 color) has revealed a potential evolutionary sequence among different light-curve types of variables. There is a possible general evolutionary (from less to more evolved) trend between the three variable types from secular to stochastic to nonvariable. For the specific classifications, the evolutionary trend for secular variables is linear to sin to sin+linear, and for stochastic variables it is burst to irregular to drop. These sequences may reflect the evolution of the envelope or accretion disk of high-mass YSOs, from large to small radii due to gravitational collapse. Although no significant variability correlation was established between the 6.7 GHz methanol maser and the W2-band emission based on the data collected so far, a number of candidates were found for further investigating the accretion burst events via future variability monitoring programs of both mid-infrared emission and masers.

Uncovering a hidden black hole binary from secular eccentricity variations of a tertiary star

We study the dynamics of a solar-type star orbiting around a black hole binary (BHB) in a nearly coplanar system. We present a novel effect that can prompt a growth and significant oscillations of the eccentricity of the stellar orbit when the system encounters an ``apsidal precession resonance,'' where the apsidal precession rate of the outer stellar orbit matches that of the inner BHB. The eccentricity excitation requires the inner binary to have a nonzero eccentricity and unequal masses, and can be created even in noncoplanar triples. We show that the secular variability of the stellar orbit's apocenter, induced by the changing eccentricity, could be potentially detectable by Gaia. Detection is favorable for BHBs emitting gravitational waves in the frequency band of the Laser Interferometer Space Antenna, hence providing a distinctive, multimessenger probe of the existence of stellar-mass BHBs in the Milky Way.

Total Solar Irradiance during the Last Five Centuries

The total solar irradiance (TSI) varies on timescales of minutes to centuries. On short timescales it varies due to the superposition of intensity fluctuations produced by turbulent convection and acoustic oscillations. On longer timescales, it changes due to photospheric magnetic activity, mainly because of the facular brightenings and dimmings caused by sunspots. While modern TSI variations have been monitored from space since the 1970s, TSI variations over much longer periods can only be estimated either using historical observations of magnetic features, possibly supported by flux transport models, or from the measurements of the cosmogenic isotope (e.g., 14C or 10Be) concentrations in tree rings and ice cores. The reconstruction of the TSI in the last few centuries, particularly in the 17th/18th centuries during the Maunder minimum, is of primary importance for studying climatic effects. To separate the temporal components of the irradiance variations, specifically the magnetic cycle from secular variability, we decomposed the signals associated with historical observations of magnetic features and the solar modulation potential Φ by applying an empirical mode decomposition algorithm. Thus, the reconstruction is empirical and does not require any feature contrast or field transport model. The assessed difference between the mean value during the Maunder minimum and the present value is ≃2.5 W m−2. Moreover it shows, in the first half of the last century, a growth of ≃1.5 W m−2, which stops around the middle of the century to remain constant for the next 50 years, apart from the modulation due to the solar cycle.

Половой диморфизм как индикатор микроэволюционной динамики соматического статуса (на модели детей грудного возраста)

Introduction. The level of sexual dimorphism, SD, is treated as independent population quantitative indice – marker of the quality of the surrounding, the level of ecological stress, the indicator of temporal fluctuations of economic and social factors. Materials and methods. Secular dynamics of SD of body dimensions is analyzed at intergroup and intragroup levels. Meta analysis embraces the data of 112 samples of urban children of 12-months-age, examined during 1930-2010 years. The main source of information – books on physical development of children and adolescents of Russia and former USSR. The second part of the work describes the monthly patterns of secular dynamics of SD of body dimensions through the age interval from 0 to 12 months based on data of Moscow children only, also from 1930s till now. The quantitative estimation of the level on SD is realized using Kullback divergence. Results. According to the results of meta analysis, secular dynamics of SD height, weight, chest and head girths of 12-months-old children is not significant (p= 0,13–0,97). Analysis of secular variability of SD of somatic dimensions of Moscow children only showed the existence of common, over temporal and over population, mechanisms of growth, in particular, increase of SD of all somatic traits under discussion through the first trimester. Intergroup differentiation of SD of anthropometric traits is minimal at the start of postnatal ontogenesis. Secular variability of age dynamics of SD of somatic traits through the infancy has nonlinear curve. SD of height and weight of the sample of 1957 for the most age points exceeds SD of both earlier samples of 1930 and 1950 and later samples of 1971 and 2008, which is connected with height rates of acceleration of post-war children. Conclusion. SD of somatic traits is an informative and autonomic indicator of microevolution and age dynamics during infancy as well as during subsequent periods of ascending ontogenesis and definite age. Nonlinear dynamics of SD levels of analyzed body dimensions through the first year of life is fixed. The most significant quantitative indicators of secular trends, fixed for several data series of Moscow infants, is SD of height.

Efficiencies of Faith and Secular Microfinance Institutions in Regions of Asia, Africa, and Latin America: A Two-Stage Dual Efficiency Bootstrap DEA Approach

Purpose: the objective is to measure the financial and social performance of 127 microfinance institutions (MFIs) and observe the effects with explanatory factors such as “type”, “geography region”, and “secular and faith” variables. Design/methodology/approach: The time-series performance analysis of microfinance institutions is determined in two stages. In the first stage, both the social and financial efficiencies are measured with Data Envelopment Analysis (DEA) approach. The two explanatory factors along with faith and secular variables show the effect on these determined efficiencies by the second stage of the Tobit regression Random effect Model. Findings: Financial performance is greater than the social performance from the first stage analysis. When considering the explanatory variables, the social performances are not significant with religious factors. When the regression is performed in a group, the financial score is more significant with religious and other explanatory variables. Faith-based and secular-based microfinance institutions are strongly significant if the performances (efficiencies) are highly maintained. Originality/Value: faith and secular variables are identified based on the background/history information of each microfinance institution (MFI).

Secular Variability of the Upwelling at the Canaries Latitude: An Instrumental Approach

AbstractIn this research we make use of historical wind direction observations to assemble an instrumental upwelling intensity index (the so‐called Directional Upwelling Index [DUI]) for the coast of Northwest Africa between 26° and 33°N and from 1825 to 2014. The DUI is defined as the persistence of the alongshore winds at the coast and unlike other upwelling indices, it relies on observed wind direction solely, avoiding the suspected bias toward increasing wind speed of historical wind observations documented in previous research. We have found that between June and October, when the upwelling intensity in the area is at its seasonal maximum, the persistence of the north‐easterlies measured by the DUI is significantly related to the alongshore wind stress and subsequently with Sea Surface Temperature anomalies at the coast of NW Africa. The analysis of the DUI record does not display a consistent long‐term trend but an oscillatory behavior. At interannual time scales this variability can be linked to the changes in the strength and location of the subtropical north Atlantic high‐pressure center and at multidecadal scales, the upwelling seems mainly driven by the Atlantic Multidecadal Variability through the modulation exerted by this climatic pattern on the intensity of the Saharan low.

The JCMT Transient Survey: Four-year Summary of Monitoring the Submillimeter Variability of Protostars

Abstract We present the four-year survey results of monthly submillimeter monitoring of eight nearby (<500 pc) star-forming regions by the JCMT Transient Survey. We apply the Lomb–Scargle Periodogram technique to search for and characterize variability on 295 submillimeter peaks brighter than 0.14 Jy beam−1, including 22 disk sources (Class II), 83 protostars (Class 0/I), and 190 starless sources. We uncover 18 secular variables, all of them protostars. No single-epoch burst or drop events and no inherently stochastic sources are observed. We classify the secular variables by their timescales into three groups: Periodic, Curved, and Linear. For the Curved and Periodic cases, the detectable fractional amplitude, with respect to mean peak brightness, is ∼4% for sources brighter than ∼0.5 Jy beam−1. Limiting our sample to only these bright sources, the observed variable fraction is 37% (16 out of 43). Considering source evolution, we find a similar fraction of bright variables for both Class 0 and Class I. Using an empirically motivated conversion from submillimeter variability to variation in mass accretion rate, six sources (7% of our full sample) are predicted to have years-long accretion events during which the excess mass accreted reaches more than 40% above the total quiescently accreted mass: two previously known eruptive Class I sources, V1647 Ori and EC 53 (V371 Ser), and four Class 0 sources, HOPS 356, HOPS 373, HOPS 383, and West 40. Considering the full protostellar ensemble, the importance of episodic accretion on few years timescale is negligible—only a few percent of the assembled mass. However, given that this accretion is dominated by events on the order of the observing time window, it remains uncertain as to whether the importance of episodic events will continue to rise with decades-long monitoring.

Quantifying Variability of Young Stellar Objects in the Mid-infrared Over 6 Years with the Near-Earth Object Wide-field Infrared Survey Explorer

Abstract Variability in young stellar objects (YSOs) can be caused by various time-dependent phenomena associated with star formation, including accretion rates, geometric changes in the circumstellar disks, stochastic hydromagnetic interactions between stellar surfaces and inner-disk edges, reconnections within the stellar magnetosphere, and hot/cold spots on stellar surfaces. We uncover and characterize ∼1700 variables from a sample of ∼5400 YSOs in nearby low-mass star-forming regions using mid-IR light curves obtained from the 6.5 yr Near-Earth Object Wide-field Infrared Survey Explorer All Sky Survey. The mid-IR variability traces a wide range of dynamical, physical, and geometrical phenomenon. We classify six types of YSO mid-IR variability based on their light curves: secular variability (linear, curved, and periodic) and stochastic variability (burst, drop, and irregular). YSOs in earlier evolutionary stages have higher fractions of variables and higher amplitudes for the variability, with the recurrence timescale of FUor-type outbursts (defined here as ΔW1 or ΔW2 > 1 mag followed by inspection of candidates) of ∼1000 yr in the early embedded protostellar phase. Known eruptive young stars and subluminous objects show fractions of variables similar to the fraction (∼55%) found in typical protostars, suggesting that these two distinct types are not distinct in variability over the 6.5 yr timescale. Along with brightness variability, we also find a diverse range of secular color variations, which can be attributed to a competitive interplay between the variable accretion luminosity of the central source and the variable extinction by material associated with the accretion process.

Analysis of factors affecting completion of growth processes in the post-puberty period

Post-puberty age is characterized by the formation of a definitive level of morphofunctional indicators of the body, the processes of social adaptation to a new after school stage of life and level of education. For age-related physiology, the post-puberty age is of interest in terms of the timing of completion of growth processes, as well as factors that determine these boundaries. Differences in the timing of completion of growth processes in juvenile age are due not only to a genetic factor, but also to a complex of epigenetic effects. This paper analyzes the literature data on factors that determine the timing of stabilization of growth processes in post-puberty age. The results of the analysis allow us to scientifically justify the conditions for the full implementation of the genotypic trait of long body size. Modern ideas about humoral mechanisms of growth regulation indicate the relationship between the secretion of growth factors and environmental conditions. Numerous studies prove the association of growth hormone with the stage of delta sleep and physical activity, somatomedin-C-with a protein diet. Growth hormone synergists in certain concentrations are insulin, sex and thyroid hormones, while glucocorticoids are antagonists. These factors allow us to explain the secular variability of the longitudinal body parameters of the generations in 19th-20th and 20th-21st centuries, depending on socio-economic conditions, lifestyle, puberty, and nutrition. The significance of the genetic factor is confirmed by differences in the timing of stabilization of body length between populations of different racial and ethnic backgrounds, and the sensitivity of growth processes to environmental factors is appeared between different geographical latitudes populations. Therefore, along with the genetic factor, climatic and geographical conditions, food quality, sleep and wake patterns, and lifestyle are determinants that affect the variability in the timing of growth processes completion in postpubertal age.

Indicators of Antarctic ozone depletion: 1979 to 2019

Abstract. The National Institute of Water and Atmospheric Research/Bodeker Scientific (NIWA–BS) total column ozone (TCO) database and the associated BS-filled TCO database have been updated to cover the period 1979 to 2019, bringing both to version 3.5.1 (V3.5.1). The BS-filled database builds on the NIWA–BS database by using a machine-learning algorithm to fill spatial and temporal data gaps to provide gap-free TCO fields over Antarctica. These filled TCO fields then provide a more complete picture of wintertime changes in the ozone layer over Antarctica. The BS-filled database has been used to calculate continuous, homogeneous time series of indicators of Antarctic ozone depletion from 1979 to 2019, including (i) daily values of the ozone mass deficit based on TCO below a 220 DU threshold; (ii) daily measures of the area over Antarctica where TCO levels are below 150 DU, below 220 DU, more than 30 % below 1979 to 1981 climatological means, and more than 50 % below 1979 to 1981 climatological means; (iii) the date of disappearance of 150 DU TCO values, 220 DU TCO values, values 30 % or more below 1979 to 1981 climatological means, and values 50 % or more below 1979 to 1981 climatological means, for each year; and (iv) daily minimum TCO values over the range 75 to 90∘ S equivalent latitude. Since both the NIWA–BS and BS-filled databases provide uncertainties on every TCO value, the Antarctic ozone depletion metrics are provided, for the first time, with fully traceable uncertainties. To gain insight into how the vertical distribution of ozone over Antarctica has changed over the past 36 years, ozone concentrations, combined and homogenized from several satellite-based ozone monitoring instruments as well as the global ozonesonde network, were also analysed. A robust attribution to changes in the drivers of long-term secular variability in these metrics has not been performed in this analysis. As a result, statements about the recovery of Antarctic TCO from the effects of ozone-depleting substances cannot be made. That said, there are clear indications of a change in trend in many of the metrics reported on here around the turn of the century, close to when Antarctic stratospheric concentrations of chlorine and bromine peaked.

The secular variability of physical development of the youth as risk factor of cardiovascular diseases

The article discusses results of complex cross-sectional and anthropometric medical check up in the M. V. Lomonosov Moscow State University in 2002-2003 and 2013. The sampling covered 494 students aged 18-23 years. The check up included basic anthropometric measurements and cardiovascular parameters. The pulse pressure and Bayevsky adaptation potential were calculated. Results. The secular trend in body mass increasing was established. So, decade variations was +3.3 kg in young men (p=0.021) and +1.8 kg in girls (p=0.098). The cardiovascular system parameters degraded over ten years: occurrence of bradycardia and tachycardia increased significantly for both genders. In most observed participants in 2002-2003 the sufficient adaptation according Bayevsky was established (75.1% in young men and 71.6% in girls). Over ten years, this proportion decreased to 44.1% in young men (p=0.0000) and to 51.7% in girls (p=0.034). The percentage of adaptation failure cases increased. Conclusions. The analysis of decade dynamics demonstrated deterioration of physical development and somatic health parameters of modern youth. The established trends should be considered in planning health improving programs targeted to early prevention of cardiovascular diseases and development of adaptive capabilities of modern youth.

A 3000-year record of vegetation changes and fire at a high-elevation wetland on Kilimanjaro, Tanzania

AbstractKilimanjaro is experiencing the consequences of climate change and multiple land-use pressures. Few paleoenvironmental and archeological records exist to examine historical patterns of late Holocene ecosystem changes on Kilimanjaro. Here we present pollen, phytolith, and charcoal (>125 μm) data from a palustrine sediment core that provide a 3000-year radiocarbon-dated record collected from a wetland near the headwaters of the Maua watershed in the alpine and ericaceous vegetation zones. From 3000 to 800 cal yr BP, the pollen, phytolith, and charcoal records show subtle variability in ericaceous and montane forest assemblages with apparent multicentennial secular variability and a long-term pattern of increasing Poaceae and charcoal. From 800 to 600 cal yr BP, montane forest taxa varied rapidly, Cyperaceae abundances increased, and charcoal remained distinctly low. From 600 yr cal BP to the present, woody taxa decreased, and ericaceous taxa and Poaceae dominated, with a conspicuously increased charcoal influx. Uphill wetland ecosystems are crucial for ecological and socioeconomic resilience on and surrounding the mountain. The results were synthesized with the existing paleoenvironmental and archaeological data to explore the high spatiotemporal complexity of Kilimanjaro and to understand historical human-environment interactions. These paleoenvironmental records create a long-term context for current climate, biodiversity, and land-use changes on and around Kilimanjaro.

Bubbling Away: Forecasting Real Estate Prices, Rents, and Bubbles in a Transition Economy

Real housing prices have both surged and swooned in formerly socialist countries. We use 2000–2017 aggregate housing sales and rental price data from Kazakhstan to explore price movements during boom and stagnation eras, investigating the rent–price ratio’s (RPR) capacity to predict housing returns and rent growth for an emerging post-Soviet economy. RPR predicts returns better during periods of price increases than declines, and its importance in predicting the bubble component diminishes with time. Short-run RPR changes are consistent with rational bubble behavior during the period of secular upswing but different predictive variables matter during price increases and declines.