Early assessment of the relationship between the COVID-19 pandemic and births in high-income countries.

Drawing on past pandemics, scholars have suggested that the COVID-19 pandemic will bring about fertility decline. Evidence from actual birth data has so far been scarce. This brief report uses data on vital statistics from a selection of high-income countries, including the United States. The pandemic has been accompanied by a significant drop in crude birth rates beyond that predicted by past trends in 7 out of the 22 countries considered, with particularly strong declines in southern Europe: Italy (-9.1%), Spain (-8.4%), and Portugal (-6.6%). Substantial heterogeneities are, however, observed.

Episodic population fragmentation and gene flow reveal a trade-off between heterozygosity and allelic richness.

In episodic environments like deserts, populations of some animal species exhibit irregular fluctuations such that populations are alternately large and connected or small and isolated. Such dynamics are typically driven by periodic resource pulses due, for example, to large but infrequent rainfall events. The repeated population bottlenecks resulting from fragmentation should lower genetic diversity over time, yet species undergoing these fluctuations appear to maintain high levels of genetic diversity. To resolve this apparent paradox, we simulated a metapopulation of constant size undergoing repeat episodes of fragmentation and change in gene flow to mimic outcomes experienced by mammals in an Australian desert. We show that episodic fragmentation and gene flow have contrasting effects on two measures of genetic diversity: heterozygosity and allelic richness. Specifically, fragmentation into many, small subpopulations, coupled with periods of infrequent gene flow, preserves allelic richness at the expense of heterozygosity. In contrast, fragmentation into a few, large subpopulations maintains heterozygosity at the expense of allelic richness. The strength of the trade-off between heterozygosity and allelic richness depends on the amount of gene flow and the frequency of gene flow events. Our results imply that the type of genetic diversity maintained among species living in strongly fluctuating environments will depend on the way populations fragment, with our results highlighting different mechanisms for maintaining allelic richness and heterozygosity in small, fragmented populations.

Long-term macrophyte and snail community responses to population declines of invasive rusty crayfish (Faxonius rusticus).

A central focus of invasive species research has been on human efforts to eradicate invaders or reduce their abundance to mitigate the worst of their impacts. In some cases, however, populations of invasive species decline without human intervention, which may inform management responses to these invaders. Such is the case of the invasive rusty crayfish (Faxonius rusticus) in northern Wisconsin, USA, where systematic population monitoring since 1975 has revealed population declines in approximately half of the lakes surveyed. Population declines of invasive species without human intervention remain understudied, but there is even less research on how communities respond following such declines. Using 10 lakes in Vilas County, Wisconsin, we investigated community recovery of habitat (macrophytes) and prey (freshwater snails) of F. rusticus following up to 33 years of declines of this invader in some lakes using a dataset with a rare, long-term span over which consistent data were collected (1987, 2002, 2011, and 2020). We compared community responses in lakes where F. rusticus populations reached a peak and subsequently declined (boom-bust lakes) and lakes where our dataset only captured the decline of F. rusticus (bust lakes) to reference lakes with consistently high or low crayfish abundance over time. We found partial recovery of macrophytes and snails in the bust and boom-bust lakes where F. rusticus has declined, with recovery of macrophyte abundance and richness in the boom-bust lakes achieving levels observed in the low-crayfish reference lakes. Snail abundance and richness increased after declines of F. rusticus, though not to the level of the low-crayfish reference lakes, suggesting that snail recovery may lag macrophyte recovery because snails are dependent on macrophytes and associated periphyton for habitat. The recovery we document potentially represents long-term ecosystem resilience of lakes to biological invasions. Our results suggest that lake communities may recover without active restoration interventions after invasive crayfish population declines, although identifying which lakes experience these natural declines remains a priority for future research and management.

Atto-Foxes and Other Minutiae.

This paper addresses the problem of extinction in continuous models of population dynamics associated with small numbers of individuals. We begin with an extended discussion of extinction in the particular case of a stochastic logistic model, and how it relates to the corresponding continuous model. Two examples of 'small number dynamics' are then considered. The first is what Mollison calls the 'atto-fox' problem (in a model of fox rabies), referring to the problematic theoretical occurrence of a predicted rabid fox density of [Formula: see text] (atto-) per square kilometre. The second is how the production of large numbers of eggs by an individual can reliably lead to the eventual survival of a handful of adults, as it would seem that extinction then becomes a likely possibility. We describe the occurrence of the atto-fox problem in other contexts, such as the microbial 'yocto-cell' problem, and we suggest that the modelling resolution is to allow for the existence of a reservoir for the extinctively challenged individuals. This is functionally similar to the concept of a 'refuge' in predator-prey systems and represents a state for the individuals in which they are immune from destruction. For what I call the 'frogspawn' problem, where only a few individuals survive to adulthood from a large number of eggs, we provide a simple explanation based on a Holling type 3 response and elaborate it by means of a suitable nonlinear age-structured model.

Family Resilience in a Resource-Cursed Community Dependent on the Oil and Gas Industry.

The economic and social well-being of rural, "resource-cursed" communities can depend on the boom-bust cycles of a single industry like oil and gas. This study used a constructivist, inductive approach to identify the challenges placed on families in one such community and the processes that strengthen family resilience. Semi-structured interviews were conducted with 35 adult residents (30-76 years old, 19 women) from a community in Alberta, Canada, that has specialized in oil and gas extraction for 70 years and experienced its worst economic downturn while the study was underway. Results showed that many families have experienced an endless cycle of poor work-life balance and income instability throughout the economic cycle. Family life often lacked social cohesion as a consequence of demanding work schedules and economic pressures. Additional challenges were the perceived negative effects of rigid gender roles, substance abuse, family conflicts, and domestic violence. Crucial strengthening processes for family resilience were fundamental financial and living standard adaptations (e.g., living within or below one's economic means; having both spouses become earners), maintaining regular contact by having a flexible home routine, and mutually agreeing to change roles during busts (former earners take responsibility for caregiving and running of the household and vice versa). Alternatively, accepting economic volatility and its impact on normal family life processes were essential for family resilience. Findings suggest the need for clinicians to help families foster resilience in communities that depend on resource extraction industries with concurrent adaptations required by individuals, families, and socio-political and economic systems.

El bienestar económico y social de las comunidades rurales "malditas por los recursos" puede depender de los ciclos de auge y caída de una industria única como la del petróleo y el gas. En este estudio se usó un método constructivista e inductivo para identificar las dificultades que enfrentan las familias en una comunidad de este tipo y los procesos que fortalecen la resiliencia familiar. Se realizaron entrevistas semiestructuradas con 35 adultos residentes (de entre 30 y 76 años, 19 mujeres) de una comunidad de Alberta, Canadá, que se ha especializado en la extracción de petróleo y gas durante 70 años y sufrió su peor recesión económica mientras el estudio estaba en marcha. Los resultados indicaron que muchas familias han pasado por un ciclo interminable de desequilibrio entre la vida personal y la laboral, y por la inestabilidad de ingresos durante todo el ciclo económico. La vida familiar con frecuencia careció de integración social como consecuencia de horarios de trabajo demandantes y presiones económicas. Otras dificultades fueron los efectos negativos percibidos de los roles de género rígidos, el abuso de sustancias, los conflictos familiares y la violencia doméstica. Los procesos de fortalecimiento esenciales para la resiliencia familiar fueron las adaptaciones fundamentales de los niveles de vida y económicos (p. ej.: vivir dentro o por debajo de los medios económicos propios; hacer que ambos cónyuges sean asalariados), mantener contacto periódico teniendo una rutina flexible en el hogar y acordar mutuamente cambiar de roles durante las recesiones (los exasalariados asumen la responsabilidad del cuidado y el funcionamiento del hogar, y viceversa). Alternativamente, aceptar la volatilidad económica y su efecto en los procesos normales de la vida familiar fue esencial para la resiliencia familiar. Los resultados indican la necesidad de que los profesionales clínicos ayuden a las familias a fomentar la resiliencia en las comunidades que dependen de las industrias de extracción de recursos mediante adaptaciones simultáneas necesarias para las personas, las familias y los sistemas sociopolíticos y económicos.

Does intrinsic light heterogeneity in Ricinus communis L. monospecific thickets drive species' population dynamics?

Ricinus communis L. colonizes heterogeneous urban landscapes as monospecific thickets. The ecological understanding on colonization success of R. communis population due to variable light availability is lacking. Therefore, to understand the effect of intrinsic light heterogeneity on species' population dynamics, R. communis populations exposed to variable light availability (low, intermediate, and high) were examined for performance strategies through estimation of key vegetative, eco-physiological, biochemical, and reproductive traits. Considerable variability existed in studied plant traits in response to available light. Individuals inhabiting high-light conditions exhibited high eco-physiological efficiency and reproductive performance that potentially confers population boom. Individuals exposed to low light showed poor performance in terms of eco-physiology and reproduction, which attribute to bust. However, individuals in intermediate light were observed to be indeterminate to light availability, potentially undergoing trait modulations with uncertainty of available light. Heterogeneous light availability potentially drives the boom and bust cycles in R. communis monospecific thickets. Such boom and bust cycles subsequently affect species' dominance, persistence, collapse, and/or resurgence as an aggressive colonizer in contrasting urban environments. The study fosters extensive monitoring of R. communis thickets to probe underlying mechanism(s) affecting expansions and/or collapses of colonizing populations.

The marriage boom and marriage bust in the United States: An age-period-cohort analysis.

In the 1950s and 1960s there was an unprecedented marriage boom in the United States. This was followed in the 1970s by a marriage bust. Some argue that both phenomena are cohort effects, while others argue that they are period effects. The study reported here tested the major period and cohort theories of the marriage boom and bust, by estimating an age-period-cohort model of first marriage for the years 1925-79 using census microdata. The results of the analysis indicate that the marriage boom was mostly a period effect, although there were also cohort influences. More specifically, the hypothesis that the marriage boom was mostly a response to rising wages is shown to be consistent with the data. However, much of the marriage bust can be accounted for by unidentified cohort influences, at least until 1980.

Survival strategies of Escherichia coli and Vibrio spp.: contribution of the viable but nonculturable phenotype to their stress-resistance and persistence in adverse environments.

In their natural ecosystems, bacteria are continuously exposed to changing environmental factors including physicochemical parameters (e.g. temperature, pH, etc.), availability of nutrients as well as interaction(s) with other organisms. To increase their tolerance and survival under adverse conditions, bacteria trigger a number of adaptation mechanisms. One of the well-known adaptation responses of the non-spore-forming bacteria is the acquisition of the viable but non-culturable (VBNC) state. This phenotype is induced by different stress factors (e.g. low temperature) and is characterized by the temporal loss of culturability, which can potentially be restored. Moreover, this response can be combined with the bust and boom strategy, which implies the death of the main population of the stressed cells (or their entry into the VBNC state) upon stress, thus enabling the remaining cells (i.e. residual culturable population) to subsist at the expense of the dead or/and VBNC cells. In this review, we discuss the characteristics of the VBNC state, its biological significance and contribution to bacterial survival.

Baby booms, busts, and population ageing in the developed world.

The key challenge facing contemporary society is a process of population ageing rooted mainly in past fertility cycles. The goals of the study reported in this paper were (i) to analyse jointly the post-1930s baby boom and the baby bust that followed, (ii) to consider the specific ways this particular combination influenced the process of ageing in different societies, and (iii) to evaluate some possible implications for policy of different historical experiences. Demographic time series for 27 nations in the developed world were used. The main results confirm the importance of the boom and bust fertility cycle of the second half of the twentieth century for population ageing. Some countries will experience ageing processes driven mainly by the growth of elderly populations while others will age largely as a result of declines in working-age populations. These differences underscore the need to tailor policy priorities for specific patterns of ageing.

Mortality during Resource Booms and Busts.

Using national data on county-level mortality, coal mining, and shale development, we examine the effects of resource booms and busts on mortality in the United States. We find evidence that decreases in operating coal mines increased total all-cause mortality, non-drug mortality, and opioid overdose mortality, especially for counties with greater than 10 operating coal mines in 2000. Our model results for drug overdose mortality and opioid overdose mortality are sensitive to the panel's start year. For shale development, the shale boom is associated with increases in non-drug suicides but otherwise had little impact on mortality. Our findings suggest a potential role for job-training programs and the cultivation of local healthcare resources in regions suffering coal busts and suicide prevention in areas with shale development.

Dynamics of bird assemblages in response to temporally and spatially variable resources in arid Australia.

Bird assemblages in arid Australia are often characterized as being highly variable through time in response to boom and bust dynamics, although the importance of habitat in structuring assemblages at a local-scale is also recognized. We use a novel approach to investigate the importance of rainfall variability in structuring bird assemblages in a resource-limited environment. Monthly bird surveys were conducted at ten plots for 8 years at a botanical and zoological park in central Australia, including five irrigated plots within a fenced area and five natural plots outside. Irrigation-used to promote growth, flowering, and fruiting of plants-created an artificial resource-enhanced environment against which the response of birds to natural fluctuations in season and rainfall were compared. Species richness was generally maintained at a higher level in resource-enhanced plots during dry times but was higher in natural plots when rainfall was high, mainly due to increases in granivores and insectivores. Honeyeaters were consistently more abundant at irrigated plots. Rainfall was important in structuring bird assemblages at all plots; however, assemblages were more stable in irrigated plots and did not respond as dramatically to a period of very high rainfall. The comparative smoothing of fluctuations in the composition and abundance of birds in irrigated areas highlights the importance of primary productivity, normally tied to rainfall, in driving temporal change in arid-zone bird communities. There was also evidence that different plots in differing habitats supported distinct bird assemblages and that this spatial distinctiveness persisted irrespective of rainfall and determined, to some extent, the response to rainfall. Our study is one of few long-term studies of arid bird assemblages and highlights the importance of both long-term cycles of productivity driven by rain and season as well as site differences in the dynamics of arid-zone bird communities. These insights are particularly valuable as climate change further exacerbates rainfall variability worldwide and initiatives to conserve avifauna in increasingly extreme environments may be required.

Latitudinal influence on gametogenesis and host-parasite ecology in a marine bivalve model.

Reproduction and parasites have significant impacts on marine animal populations globally. This study aimed to investigate the associative effects of host reproduction and a host-parasite interplay on a marine bivalve, along a geographic gradient of latitude. Cockles Cerastoderma edule were sampled from five European sites (54°N to 40°N), between April 2018 and October 2019. A histological survey provided data on trematode (metacercaria and sporocyst life stages), prevalence, and cockle stage of gametogenesis to assess the influence of a latitudinal gradient on both interplays. Sex ratios at the northernmost sites were skewed toward females, and spawning size was reduced at the lower latitudes. Trematode infection did not follow a latitudinal gradient. Localized site-related drivers, namely seawater temperature, varied spatially, having an impact on cockle-trematode interactions. Spawning was related to elevated temperatures at all sites. Prolonged spawning occurred at southern latitudes, where seawater temperatures were warmer. Trematode prevalence and the impact of trematodes on gametogenesis were found to be spatially variable, but not latitudinally. Therefore, it is not possible to determine the likelihood of boom and bust events in cockles, based on the latitudinal location of a population. In terms of sublethal impacts, it appeared that energy was allocated to reproduction rather than somatic growth in southern populations, with less energy allocated to reproduction in the larger, northern cockles. The demonstrated spatial trend of energy allocation indicates the potential of a temporal trend of reduced cockle growth at northern sites, as a result of warming sea temperatures. This awareness of the spatially varying drivers of populations is crucial considering the potential for these drivers/inhibitors to be exacerbated in a changing marine environment.

Resilience in Times of Economic Boom and Bust: A Narrative Study of a Rural Population Dependent upon the Oil and Gas Industry.

How do residents of small towns that depend on oil and gas extraction or processing industries withstand economic boom and bust cycles? To answer this question, this article reports on a narrative analysis of residents' life stories gathered from 37 adults of a small town on the Canadian prairies dependent on the oil and gas industry, employing the theories of narrative inquiry and narrative identity. Participants aged 30 to 76 were interviewed and their experiences of living in an unstable economy that is dependent mostly on a single resource extraction industry were explored. Specifically, we asked participants about the effect of economic change on factors related to resilience like family interactions, work choices, educational pathways, and the quality of their social lives. Our analysis of adult narratives looked for patterns in the relationship between risk exposure, promotive and protective factors at multiple systemic levels (individual, relational, cultural), and functional outcomes such as individual coping, community cohesion, and social and economic sustainability. Results show that a strong identity, in particular expressions of personal agency, communion, and engagement in meaning making are contributing factors to adult resilience in a context of economic change. Our results also highlight how positive attitudes towards a better future may inadvertently undermine the need for residents of oil and gas-dependent towns to commit to economic diversification and other potential resilience-promoting strategies.

Belief reversals as phase transitions and economic fragility: a complexity theory of financial cycles with reflexive agents.

This paper aims to contribute to the analysis of expectations and belief reversals in a evolutionary and complexity economics framework. It formulates its analysis in terms of the concept of reflexivity, drawing on the ideas regarding reflexivity in financial markets of George Soros, and lays out a model of how a financial cycle expresses a systematic pattern of interacting feedback effects. The paper develops this analysis as a complex interaction between sets of heterogeneous expectations derived from the behavior of reflexive economic agents. Positive and negative feedback phases in a cycle are distinguished and associated with boom and bust stages of that cycle. A central role is played by agents' beliefs and judgments underlying their expectations, and how those beliefs and judgments in uncertain circumstances are changeable and subject to abrupt reversals which can manifest themselves in "Minsky moments." The paper argues that agents' belief reversals result from their misconceptions about causal processes in booms and upswings, a misconception that reflects their tendency to think causally in terms of negative feedback patterns rather than positive ones.

Sedentary behaviour facilitates conditioned pain modulation in middle-aged and older adults with persistent musculoskeletal pain: a cross-sectional investigation.

INTRODUCTION: Higher physical activity (PA) and lower sedentary behaviour (SB) levels have demonstrated beneficial effects on temporal summation (TS) and conditioned pain modulation (CPM) in healthy adults. This cross-sectional study investigated the relationships between PA and SB and TS/CPM responses in individuals with chronic musculoskeletal pain. METHODS: Sixty-seven middle-aged and older adults with chronic musculoskeletal pain were recruited from the community. Questionnaires measuring demographics, pain, and psychological measures were completed. Physical activity/SB levels were measured using the International Physical Activity Questionnaire-short form and Sedentary Behaviour Questionnaire, respectively. Semmes monofilament was used to assess mechanical TS (MTS) at the most symptomatic (MTS-S) and a reference region (MTS-R); change in the pain scores (baseline-10th application) was used for analysis. Conditioned pain modulation procedure involved suprathreshold pressure pain threshold (PPT-pain4) administered before and after (CPM30sec, CPM60sec, and CPM90sec) conditioning stimulus (2 minutes; ∼12°C cold bath immersion). For analysis, PPT-pain4 (%) change scores were used. RESULTS: PPT-pain4 (%) change scores at CPM30sec and CPM60sec demonstrated significant weak positive correlations with SB levels and weak negative correlations with PA measures. After adjusting for confounding variables, a significant positive association was found between SB (h/d) and PPT-pain4 (%) change scores at CPM30sec and CPM60sec. No significant associations between MTS and PA/SB measures. CONCLUSION: Sedentariness is associated with higher pain inhibitory capacity in people with chronic musculoskeletal pain. The observed relationship may be characteristic of a protective (sedentary) behaviour to enhance pain modulatory mechanism. Prospective longitudinal studies using objective PA/SB measures are required to validate the observed relationship in a larger sample size.

Formulating spread of species with habitat dependent growth and dispersal in heterogeneous landscapes.

Habitat heterogeneity can have profound effects on the spreading dynamics of invasive species. Using integro-difference equations, we investigate the spreading dynamics in a one-dimensional heterogeneous landscape comprising alternating favourable and unfavourable habitat patches or randomly generated habitat patches with given spatial autocorrelation. We assume that population growth and dispersal (including emigration probability and dispersal distance) are dependent on habitat quality. We derived an approximation of the rate of spread in such heterogeneous landscapes, suggesting the sensitivity of spread to the periodic length of the alternating favourable and unfavourable patches, as well as their spatial autocorrelation. A dispersal-limited population tends to spread faster in landscapes with shorter periodic length. The spreading dynamics in a heterogeneous landscape was found to be not only dependent on the availability of favourable habitats, but also the dispersal strategy. Estimates of time lag before detection and the condition for boom-and-bust spreading dynamics were explained. Furthermore, rates of spread in heterogeneous landscapes and corresponding homogeneous landscapes were compared, using weighted sums of vital rates.

The Breast Size Rating Scale: Development and psychometric evaluation.

Existing measures of breast size dissatisfaction have poor ecological validity or have not been fully evaluated in terms of psychometric properties. Here, we report on the development of the Breast Size Rating Scale (BSRS), a novel measure of breast size dissatisfaction consisting of 14 computer-generated images varying in breast size alone. Study 1 (N=107) supported the scale's construct validity, insofar as participants were able to correctly order the images in terms of breast size. Study 2 (N=234) provided evidence of the test-retest reliability of BSRS-derived scores after 3 months. Studies 3 (N=730) and 4 (N=234) provided evidence of the convergent validity of BSRS-derived breast size dissatisfaction scores, which were significantly associated with a range of measures of body image. The BSRS provides a useful tool for researchers examining women's breast size dissatisfaction.

Demographics and housing in America.

PIP: Family-building needs of the "nesting" generation and its offspring, the baby boomers born 1947-1964, dominated post-World War 2 housing demand and production to 1970. Centered on tract-house suburbia, annual housing starts averaged 1.5 million a year in the 1950s and 1960s. With growing real median family incomes, the average size of new dwellings increased and 63% of households owned their homes by 1970, compared to 44% in 1940. The baby boomers' arrival at the ages of household formation sparked the "Golden Housing Age" of the 1970s. Net household increase averaged a record 1.7 million a year and 19 million year-round dwellings were added to the national inventory compared to 11 million in the 1950s and 1960s, despite a plunge in housing starts during the 1974-75 recession. Real median family income declined after 1973 and inflation escalated housing costs but at the same time fueled demand for housing as an investment hedge against inflation. The singles and "mingles" life styles of youthful baby boomers boosted rental housing, condominiums, and compact townhouses. Married-couple households dropped from 74% of the total in 1960 to 58% in 1975. Household formation and housing starts dropped drastically with the 1980-82 recession but bounced back as the economy recovered in 1983-85 and restrained inflation braked housing cost rises. Projections show overall household increases reduced to barely a million a year in 1990-95, with renter household gains at just 175,000, compared to 1/2 a million a year in the 1970s, as the household-formation ages of 18-34 are taken over by the baby bust generation. This will be offset by the baby boomers' maturing into middle age. By 1995 most of the giant generation will be in the peak-earning, high-homeownership ages of 35-54. Married-couple households in this age bracket will account for 56% of the household gain from 1983 to 1995, boosting national affluence and the demand for upscale housing, likely to be located in the suburbs.^ieng

The baby boom, the baby bust, and the housing market.

PIP: This paper explores the impact of demographic changes on the housing market in the US, 1st by reviewing the facts about the Baby Boom, 2nd by linking age and housing demand using census data for 1970 and 1980, 3rd by computing the effect of demand on price of housing and on the quantity of residential capital, and last by constructing a theoretical model to plot the predictability of the jump in demand caused by the Baby Boom. The Baby Boom in the U.S. lasted from 1946-1964, with a peak in 1957 when 4.3 million babies were born. In 1980 19.7% of the population were aged 20-30, compared to 13.3% in 1960. Demand for housing was modeled for a given household from census data, resulting in the finding that demand rises sharply at age 20-30, then declines after age 40 by 1% per year. Thus between 1970 and 1980 the real value of housing for an adult at any given age jumped 50%, while the real disposable personal income per capita rose 22%. The structure of demand is such that the swelling in the rate of growth in housing demand peaked in 1980, with a rate of 1.66% per year. Housing demand and real price of housing were highly correlated and inelastic. If this relationship holds in the future, the real price of housing should fall about 3% per year, or 47% by 2007. The theoretical model, a variation of the Poterba model, ignoring inflation and taxation, suggests that fluctuations in prices caused by changes in demand are not foreseen by the market, even though they are predictable in principle 20 years in advance. As the effects of falling housing prices become apparent, there may be a potential for economic instability, but people may be induced to save more because their homes will no longer provide the funds for retirement.^ieng

Simulating alternative social security responses to the demographic transition.

"This paper uses a perfect foresight life cycle simulation model to examine the dynamic economic effects of baby 'booms' and baby 'busts' as well as the interaction of such demographic changes with social security policy. Demographic change can have sizeable short and long-run effects on saving rates and factors returns." The geographic focus is on the United States. "The model predicts long-run improvement in welfare associated with a prolonged baby bust. This improvement holds even in the absence of accommodating social security policy. It reflects a long-run decline in the dependency ratio, with the reduction in dependent children per worker more than offsetting the increase in retirees per worker."