With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how ...With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how it responds to demographic dynamics,particularly in emerging economies like China.Using the two-stage Quadratic Almost Demand System(QUAIDS)model,this study empirically examines the impact of demographic dynamics on food consumption and its environmental outcomes based on the provincial data from 2000 to 2020 in China.Under various scenarios,according to changes in demographics,we extend our analysis to project the long-term trend of food consumption and its environmental impacts,including greenhouse gas(GHG)emissions,water footprint(WF),and land appropriation(LA).The results reveal that an increase in the proportion of senior people significantly decreases the consumption of grain and livestock meat and increases the consumption of poultry,egg,and aquatic products,particularly for urban residents.Moreover,an increase in the proportion of males in the population leads to higher consumption of poultry and aquatic products.Correspondingly,in the current scenario of an increased aging population and sex ratio,it is anticipated that GHG emissions,WF,and LA are likely to decrease by 1.37,2.52,and 3.56%,respectively.More importantly,in the scenario adhering to the standards of nutritional intake according to the Dietary Guidelines for Chinese Residents in 2022,GHG emissions,WF,and LA in urban areas would increase by 12.78,20.94,and 18.32%,respectively.Our findings suggest that changing demographics should be considered when designing policies to mitigate the diet-environment-health trilemma and achieve sustainable food consumption.展开更多
Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China...Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China were selected as samples in this study using a multistage cluster random sampling method.The basic information questionnaire and Constitution in Chinese Medicine Questionnaire(Elderly Edition)were used.Descriptive statistical analysis,chi-squared tests,and binary logistic regression analysis were used.Results: The single balanced constitution(BC)accounted for 23.9%.The results of the major TCM constitution types showed that BC(43.2%)accounted for the largest proportion and unbalanced constitutions ranged from 0.9%to 15.7%.East China region(odds ratio[OR]=2.097;95%confidence interval[CI],1.912 to 2.301),married status(OR=1.341;95%CI,1.235 to 1.457),and managers(OR=1.254;95%CI,1.044 to 1.505)were significantly associated with BC.Age>70 years was associated with qi-deficiency constitution and blood stasis constitution(BSC).Female sex was significantly associated with yang-deficiency constitution(OR=1.646;95%CI,1.52 to 1.782).Southwest region was significantly associated with phlegm-dampness constitution(OR=1.809;95%CI,1.569 to 2.086).North China region was significantly associated with inherited special constitution(OR=2.521;95%CI,1.569 to 4.05).South China region(OR=2.741;95%CI,1.997 to 1.3.763),Central China region(OR=8.889;95%CI,6.676 to 11.835),senior middle school education(OR=2.442;95%CI,1.932 to 3.088),and managers(OR=1.804;95%CI,1.21 to 2.69)were significantly associated with BSC.Conclusions: This study defined the distribution characteristics and demographic factors of TCM constitution in the elderly population.Adjusting and improving unbalanced constitutions,which are correlated with diseases,can help promote healthy aging through the scientific management of these demographic factors.展开更多
“Human-elephant conflict(HEC)”,the alarming issue,in present day context has attracted the attention of environmentalists and policy makers.The rising conflict between human beings and wild elephants is common in Bu...“Human-elephant conflict(HEC)”,the alarming issue,in present day context has attracted the attention of environmentalists and policy makers.The rising conflict between human beings and wild elephants is common in Buxa Tiger Reserve(BTR)and its adjoining area in West Bengal State,India,making the area volatile.People’s attitudes towards elephant conservation activity are very crucial to get rid of HEC,because people’s proximity with wild elephants’habitat can trigger the occurrence of HEC.The aim of this study is to conduct an in-depth investigation about the association of people’s attitudes towards HEC with their locational,demographic,and socio-economic characteristics in BTR and its adjoining area by using Pearson’s bivariate chi-square test and binary logistic regression analysis.BTR is one of the constituent parts of Eastern Doors Elephant Reserve(EDER).We interviewed 500 respondents to understand their perceptions to HEC and investigated their locational,demographic,and socio-economic characteristics including location of village,gender,age,ethnicity,religion,caste,poverty level,education level,primary occupation,secondary occupation,household type,and source of firewood.The results indicate that respondents who are living in enclave forest villages(EFVs),peripheral forest villages(PFVs),corridor village(CVs),or forest and corridor villages(FCVs),mainly males,at the age of 18–48 years old,engaged with agriculture occupation,and living in kancha and mixed houses,have more likelihood to witness HEC.Besides,respondents who are illiterate or at primary education level are more likely to regard elephant as a main problematic animal around their villages and refuse to participate in elephant conservation activity.For the sake of a sustainable environment for both human beings and wildlife,people’s attitudes towards elephants must be friendly in a more prudent way,so that the two communities can live in harmony.展开更多
BACKGROUND The Limb Lengthening and Reconstruction Society(LLRS)is a premier orthopedic specialty organization that promotes limb reconstruction for all ages.LLRS membership characteristics,however,are poorly reported...BACKGROUND The Limb Lengthening and Reconstruction Society(LLRS)is a premier orthopedic specialty organization that promotes limb reconstruction for all ages.LLRS membership characteristics,however,are poorly reported.This study delineates orthopedic surgeon LLRS members’demographic traits,academic achievement,leadership attainment,and geographical distribution across the United States.AIM To inform aspiring orthopedic professionals,as well as to promote growth and diversity in both the LLRS organization and overarching field.METHODS This cross-sectional study examined United States LLRS members’academic,leadership,demographic,and geographical attributes.After reviewing the 2023 LLRS member directory,Google search results were matched to the listings and appended to the compiled data.Sex and ethnicity were evaluated visually utilizing retrieved images.The Hirsch index(H-index)of academic activity,residency and fellowship training,other graduate degrees,leadership positions,practice type(academic or non-academic),and spoken languages were categorized.LLRS members per state and capita determined geographic distribution.The Mann Whitney U test was applied to compare H-index between males and females,as well as to assess member differences pertaining to affiliation with academic vs non-academic practice facilities.RESULTS The study included 101 orthopedic surgeons,78(77.23%)Caucasian and 23(22.77%)non-Caucasian,79(78.22%)male and 22(21.78%)female.Surgeons with DO degrees comprised only 3.96%(4)of the cohort,while the vast majority held MDs[96.04%(97)].Mean H-index was 10.55,with male surgeons having a significantly higher score(P=0.002).Most orthopedic surgeons(88.12%,)practiced in academic centers.Of those professionals who occupied leadership positions,14%were women,while 86%were men.Additionally,19(37.25%)United States regions and the District of Columbia lacked an LLRS-member orthopedic surgeon.Total per capita rate across the United States was 0.30 LLRS orthopedic surgeons per 1 million people.CONCLUSION Over 21%of LLRS members are women,surpassing prior benchmarks noted in orthopedic faculty reporting.LLRS members’high research productivity scores imply field dedication that can refine expertise in the limb lengthening and reconstruction space.Gender disparities in leadership remain,however,necessitating greater equity efforts.A low rate of LLRS representation per capita must be addressed geographically as well,to affect improvements in regional care access.This study can serve to support aspiring orthopedic professionals,inform diversity,leadership,and field advancement strategies,and maintain the continued goal of enhanced patient care worldwide.展开更多
Background: In Sub-Saharan Africa, pre-eclampsia remains a major health problem contributing to high rates of maternal mortality. Despite this condition having adverse effects on maternal and child health, its prevale...Background: In Sub-Saharan Africa, pre-eclampsia remains a major health problem contributing to high rates of maternal mortality. Despite this condition having adverse effects on maternal and child health, its prevalence and associated risk factors are still significant, especially in developing countries including Ghana. This study aimed to assess the prevalence and demographic distributions associated with pre-eclampsia among pregnant women at the Ho Teaching Hospital. Methods: A facility-based retrospective study was conducted by reviewing available data or hospital records of pregnant mothers admitted to the labor and maternity wards from January 2018 to December 2020. All pregnant women who were diagnosed with pre-eclampsia within this period were included in the study. The data were collected using a structured checklist. Results: 5609 data on pregnant women from 2018 to 2020 were recorded. Out of the 5609 data recorded, 314 pre-eclampsia cases were recorded giving an overall prevalence of 5.6%. The yearly prevalence for 2018, 2019, and 2020 were 4.6%, 5.6%, and 6.6%, respectively. The most recorded pre-eclampsia cases were seen among women within the age group of 18 - 24 years. The data showed that 112 (35.7%) of the pregnant women who had pre-eclampsia were nulliparous. Pre-eclampsia-associated maternal and fetal complications were;preterm delivery 221 (70.4%), intrauterine fetal death 62 (19.7%), eclampsia 9 (2.9%), HELLP syndrome 5 (1.6%) and maternal death 17 (5.4%). Associated factors of pre-eclampsia were parity, level of education, and occupation (p ≤ 0.05). Conclusion: The findings of this study showed a rising trend in the incidence of pre-eclampsia over the years at the Ho Teaching Hospital. Parity, level of education, and occupation were found to be associated with developing pre-eclampsia.展开更多
Globally,population dynamics are shifting towards increased life expectancy,and many countries,including Greece,face significant demographic challenges.Greece is particularly impacted by one of the lowest birth rates ...Globally,population dynamics are shifting towards increased life expectancy,and many countries,including Greece,face significant demographic challenges.Greece is particularly impacted by one of the lowest birth rates in the world and a rapidly aging population.This demographic shift places unprecedented pressure on the nation’s pension systems and economic stability,as more people retire than enter the workforce.This study aims to explore the historical factors contributing to Greece’s demographic situation,analyze the consequences of current trends,and propose strategic solutions.The research utilizes a literature review approach and the case study of Greece to understand the depth and breadth of the demographic crisis.Key areas of focus include the declining birth rate,the economic implications of an aging population,and the potential of migration and policy reform to rejuvenate demographic dynamics.The study evaluates various policy interventions from other countries to propose a tailored,multi-faceted strategy for Greece.These strategies emphasize economic incentives for young families,improved childcare and parental support,healthcare investment,and inclusive migration policies to enhance workforce numbers.This comprehensive approach seeks to provide actionable insights that can help Greece mitigate the effects of demographic decline and foster a more sustainable future,aligning policy interventions with socio-economic and cultural realities.展开更多
The decline in the birth rate,which has been uninterrupted in Italy since the mid-1960s,has had a significant impact on many aspects of society.As far as the educational system is concerned,this phenomenon has acted l...The decline in the birth rate,which has been uninterrupted in Italy since the mid-1960s,has had a significant impact on many aspects of society.As far as the educational system is concerned,this phenomenon has acted like a wave,first causing a decline in the population of the first school age groups,then in the other groups,until recently affecting the 19-25 age group,which includes the majority of university students.As a result,the majority of Italian universities have seen a decline over time in both enrollments(matriculations)and student numbers(enrollments),although the situation varies from one area to another.In the Mezzogiorno,this trend is even more pronounced,since an increasing number of resident students tend to favor universities in the Centre-North,creating a South-Centre-North movement,which could be compared to a particular form of cultural tourism,without a similar flow in the opposite direction.Finally,the study highlights the probable consequences of the recent demographic depopulation on the future trend of university enrollment of residents aged 19-25 in the Calabria region,using the most recent demographic projections of Istat and constructing two evolutionary scenarios.In the first scenario,we have assumed that in the near future university enrollment rates remain constant throughout the period considered;in the second scenario,these rates instead experience a gradual and continuous increase.These results could be useful if further forecasts of university enrollments were to be made at the level of individual Calabrian universities.展开更多
Background: Autosomal dominant polycystic kidney disease (ADPKD) is an important etiological factor causing chronic kidney disease (CKD), cardiovascular diseases and hypertension (HT). The purpose of the present study...Background: Autosomal dominant polycystic kidney disease (ADPKD) is an important etiological factor causing chronic kidney disease (CKD), cardiovascular diseases and hypertension (HT). The purpose of the present study is to investigate the clinical information and demographic characteristics of autosomal dominant polycystic kidney disease patients who received treatment at our hospital for the last five years. Material and Method: Among 21400 people who sought care at Siirt State Hospital Urology and Nephrology Outpatient Clinics between January 2015 and January 2020 for various reasons, a total of 36 patients experiencing autosomal dominant polycystic kidney disease were included in the present research. Retrospective patient file access was used to gather demographic information and laboratory data. Results: The study included 36 patients in all, 25 (69.4%) male and 11 (30.6%) female. The patient’s average age was 50.8 ± 19.0. The average age at diagnosis was 43.4 ± 17.2. Family history was positive in 29 (80.5%) of the patients. There were hypertension in 27 (75.0%) patients, coronary artery disease in five (13.9%) patients, diabetes mellitus in five (13.9%) patients, left ventricular hypertrophy in 18 (50%) patients, proteinuria in 11 (30.6%) patients, and six (16.7%) patients had macroscopic hematuria. Liver cysts were found in 23 (63.9%) of the patients and nephrolithiasis in eight (22.2%). Discussion: Hypertension is the most common finding when clinical and demographic data of autosomal dominant polycystic kidney disease are examined. Providing blood pressure control reduces the risk of death due to left ventricular hypertrophy and slows down the rate at which chronic kidney disease progresses. The rate was found to be 80.5% for patients with a positive family history. It may be possible to diagnose and treat people with autosomal dominant polycystic kidney disease earlier by screening their family members.展开更多
China needs a proactive response to negative population growth The year 2022 will most likely be remembered as a turning point in any future discussion on China’s demographics.That year,the world’s most populous cou...China needs a proactive response to negative population growth The year 2022 will most likely be remembered as a turning point in any future discussion on China’s demographics.That year,the world’s most populous country entered an“era of negative population growth.”Its natural population growth rate slid to 0.6 per thousand from 2021’s 0.34 per thousand,the nation’s overall population declined by 850,000 people year-on-year,and new births fell below 10 million for the first time since 1950,data from the National Bureau of Statistics showed.展开更多
A great discovery made by H. von Foerster, P. M. Mora and L. W. Amiot was published in a 1960 issue of “Science”. The authors showed that existing data for calculating the Earth’s population in the new era (from 1 ...A great discovery made by H. von Foerster, P. M. Mora and L. W. Amiot was published in a 1960 issue of “Science”. The authors showed that existing data for calculating the Earth’s population in the new era (from 1 to 1958) could be described with incredibly high proximity by a hyperbolic function with the point of singularity on 13 November 2026. Thus, empirical regularity of the rise of the human population was established, which was marked by explosive demographic growth in the 20<sup>th</sup> century when during only one century it almost quadrupled: from 1.656 billion in 1900 to 6.144 billion in 2000. Nowadays, the world population has already overcome 7.8 billion people. Immediately after 1960, an active search for phenomenological models began to explain the mechanism of the hyperbolic population growth and the following demographic transition designed to stabilize its population. A significant role in explaining the mechanism of the hyperbolic growth of the world population was played by S. Kuznets (1960) and E. Boserup (1965), who found out that the rates of technological progress historically increased in proportion to the Earth’s population. It meant that the growth of the population led to raising the level of life-supporting technologies, and the latter in its turn enlarged the carrying capacity of the Earth, making it possible for the world population to expand. Proceeding from the information imperative, we have developed the model of the demographic dynamics for the 21<sup>st</sup> century for the first time. The model shows that with the development and spread of Intelligent Machines (IM), the number of the world population reaching a certain maximum will then irreversibly decline. Human depopulation will largely touch upon the most developed countries, where IM is used intensively nowadays. Until a certain moment in time, this depopulation in developed countries will be compensated by the explosive growth of the population in African countries located south of the Sahara. Calculations in our model reveal that the peak of the human population of 8.52 billion people will be reached in 2050, then it will irreversibly go down to 7.9 billion people by 2100, if developed countries do not take timely effective measures to overcome the process of information depopulation.展开更多
Given the great strides that China's education sector has made in recent decades, it can be expected that the overall workforce quality of exiting China's labor market in coming one or two decades will be relatively...Given the great strides that China's education sector has made in recent decades, it can be expected that the overall workforce quality of exiting China's labor market in coming one or two decades will be relatively low, while the overall quality of workforce newly entering into China's labor market will be high. As the new, bettereducated generation takes over, China's workforce quality will be vastly improved. This in turn will promote economic growth. We refer to economic growth arising from improved workforce quality as qualitative demographic dividend. Using the computable general equilibrium (CGE) model, this paper investigates the relationship between workforce quality improvements and economic growth. According to the model's results, an improvement in workforce quality will raise the economic growth rate by about two percentage points per annum between 2016 and 2020 and by 10 percentage points cumulatively by 2020. In other words, GDP will be 1.1 times the level of baseline GDP by 2020 due to the improved education levels. Given different production functions across sectors, the improvement of workforce quality will affect different sectors in different ways. On the whole, the improvement of workforce quality is more favorable to the development of capital-intensive sectors and sectors with rapid technology progress. According to this paper, considering the improvement of workforce quality, we cannot conclude that China's potential economic growth rate has already begun to decline. Despite diminishing conventional quantitative demographic dividends, China "s qualitative demographic dividends will keep rising. Qualitative demographic dividends will further push forward China's industrial restructuring and the strategic transition of industrial competitiveness from quantitative to qualitative and from an extensive to an intensive pattern of development.展开更多
[Objective] The aim was to analyze the phenomenon of employment diffi- culty and labor shortage, and to reveal the influencing factors of employment difli- culty and labor shortage. [Method] On the basis of the econom...[Objective] The aim was to analyze the phenomenon of employment diffi- culty and labor shortage, and to reveal the influencing factors of employment difli- culty and labor shortage. [Method] On the basis of the economic principle of popu- lation dividend, the use of human resources and natural resource constraints The IS-LM model describes these two states. [Results] The resource constraints have a "squeeze" effect on the demographic dividend, and employment pressure is shown in terms of the population opportunity window; the labor market segmentation, the ir- rational industrial structure, the backward curriculum and employment concept are the main factors affecting employment and labor shortage. [Conclusion] The way to solve this dilemma must be removed from the division of labor market, the adjust- ment of industrial structure, the setting of university specialty, the change of em- ployment concept of university graduates as well as the improvement of the quality of labor.展开更多
This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the ...This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the direction of demographic transition and whether or not it has finished. Apart from establishing new theories of demographic transition and the trasition of demographic structure, this paper differentiates the concepts of "relative surplus population" and "relative suitable population," and "relative insufficient population" and identifies key demographic differences along the way. In doing so, this paper argues that China's demographic strueture is undergoing a process of rebalancing.展开更多
Worldwide, the incidence of birth defects in low-income countries is 6.42%, while in middle-income and high-income countries it is 5.57% and 4.72%, respectively;approximately 303, 000 newborns die from birth defects e...Worldwide, the incidence of birth defects in low-income countries is 6.42%, while in middle-income and high-income countries it is 5.57% and 4.72%, respectively;approximately 303, 000 newborns die from birth defects each year. In China, the incidence of birth defects is about 5.6%, and around 8.14 million people have congenital disabilities, accounting for 9.6% of total disabled people[1]. Birth defect remains a major clinical and public health challenge because of its high fatality rate and protracted and severe sequela.展开更多
To identify the determinant of the occurrence of IUD expulsion Materials & Methods Based on 25 733 IUD uses from the Chinese Two per Thousand Fertility Survey data, this study examines the patterns and differe...To identify the determinant of the occurrence of IUD expulsion Materials & Methods Based on 25 733 IUD uses from the Chinese Two per Thousand Fertility Survey data, this study examines the patterns and differentials of IUD expulsion rate by characteristics of women, and identifies the socio demographic determinants of IUD expulsion. A Life Table method was used to calculate the cumulative expulsion rate and a random effects discrete time survival model was employed to assess the impact of potential determinants simultaneously on the risk of expelling an IUD. Results Three major findings are observed in this study. First, IUD expulsion was the second main reason, after pregnancy during IUD use, for IUD discontinuation during the first four years of IUD insertion; the expulsion rates were 6.4%, 9.1%, 10.8 %, and 12.0% at 12, 24, 36 and 48 months, respectively. Second, there was a clustering of IUD expulsion: some women experienced repeated IUD expulsions. Third, some socio demographic characteristics and fertility history were associated with the occurrence of IUD expulsion. In particular, the expulsion rate was high among young women, among those with two or more children and among those living in rural areas. Conclusion The above mentioned factors shoald be addressed in order to decrease the IUD expulsion rate and enhance the reprocluctive he alth of women.展开更多
The objective of social development is to construct a harmonious society.In China,the key to a harmonious society is the happiness of more than 900 million farmers living in the rural areas.This study aimed to measure...The objective of social development is to construct a harmonious society.In China,the key to a harmonious society is the happiness of more than 900 million farmers living in the rural areas.This study aimed to measure rural residents' subjective well-being(SWB) through the day reconstruction method,as well as to analyze SWB's influencing factors through a variety of statistical methods.The results showed that the average U index was 12.79%,indicating that respondents were unhappy 12.79% of the time.Twenty-seven percent of the population had a U index greater than 0,with the average value being 47%,indicating that these people were unhappy 47% of the time.The study also found that SWB varied according to the characteristics of the respondents.Logistic regression analysis showed that social and demographic factors,including age,education,county,household size,generation number,per capita income,migration status and social networking,which significantly affected rural residents' SWB.The size of the impact varied with the different factors.展开更多
Drawn on the data collected by surveying 1 340 urban households from six cities in China, this paper estimates the impacts of demographic structure and population aging on household meat consumption, by jointly consid...Drawn on the data collected by surveying 1 340 urban households from six cities in China, this paper estimates the impacts of demographic structure and population aging on household meat consumption, by jointly considering meat consumed at home and away from home. Based on the trajectories of population, a simple simulation on meat demand trend in China is conducted subsequently. The results suggest: 1) Meat consumed away from home averagely accounts for near 30% of household total meat consumption in terms of quantity, so that its omission likely leads to a significant underestimate of total meat consumption and misunderstanding the driving forces; 2) population aging significantly and negatively affects per capita meat consumption, suggesting that the expected meat demand in China without considering population aging will be overestimated. The findings from this study have important implications for better understanding the relative issues on China's meat consumption under the situation of population aging.展开更多
Background: The first three censuses of the 50-ha plot at Barro Colorado Island spanned an unusually harsh dry season during the 1983 El Nitro. By the early 1990s, we had documented increases in tree mortality, tree ...Background: The first three censuses of the 50-ha plot at Barro Colorado Island spanned an unusually harsh dry season during the 1983 El Nitro. By the early 1990s, we had documented increases in tree mortality, tree growth, and large population fluctuations of many species during the 1982-1985 census interval. At the time, we asserted that increasing drought frequency would greatly affect the forest. With the benefit of five more censuses at Barro Colorado from 1995-2015, we can now put the 1980 conditions in a longer perspective and test the hypothesis that increasing droughtiness has continued to change the forest. Methods: A 50-ha forest plot on Barro Colorado Island was censused eight times, in 1982 and every five years since 1985. All free-standing woody stems were measured, mapped, and identified in each census. Results: 1) The period 1982-1992 included several extreme dry seasons, not just 1983, but since then there have been few such droughts. 2) Dbh growth declined from a peak in the early 1980s to its lowest in the early 1990s. From 1995-2015 it increased slightly, but not returning to the initial peak. Nearly every species and all dbh categories followed the same pattern. 3) The elevated stand-wide mortality rate of large trees during the 1982-1985 drought has not returned, and most individual species showed the same pattern of elevated mortality in the 1980s followed by low and fairly stable mortality after 1990. 4) Sapling mortality declined after 198,5, but rose again in the late-90s, so the 1980s drought period no longer looks unusual. Mortality of individual species' saplings fluctuated erratically, including cases where mortality during the drought was lower than after. 5) Population sizes of individual species fluctuated in all possible directions. Some species declined precipitously during the drought, then recovered, but others did not recover. Other species increased in abundance during the drought. Conclusions" Droughts of the 1980s elevated tree growth and mortality at Barro Colorado, but since 1990, demographic rates have remained lower, paralleling a moderate climate with few severe droughts after 1990. Moisture-demanding species suffered during the drought, but many have since recovered. We do not know how often such drought periods recur. Moreover, many species' abundances fluctuated over 35 years with no known cause.展开更多
Is China able to maintain fast growth after three decades? This paper tries to answer this question by: 1) arguing that factors contributed to sustained long-run growth at supply side;2) focusing on contributions ...Is China able to maintain fast growth after three decades? This paper tries to answer this question by: 1) arguing that factors contributed to sustained long-run growth at supply side;2) focusing on contributions of demographic dividend especially that of rural-urban migration;and 3) analyzing rural demographic change with information collected through village-wide household survey.Policy alternatives to realize remaining potential demographic dividend are proposed based on the analysis of changing rural demographic structure.展开更多
Palaeognathae includes ratite and tinamou species that are important for understanding early avian evolution.Here,we analyzed the whole-genome sequences of 15 paleognathous species to infer their demographic histories...Palaeognathae includes ratite and tinamou species that are important for understanding early avian evolution.Here,we analyzed the whole-genome sequences of 15 paleognathous species to infer their demographic histories,which are presently unknown.We found that most species showed a reduction of population size since the beginning of the last glacial period,except for those species distributed in Australasia and in the far south of South America.Different degrees of contraction and expansion of transposable elements(TE)have shaped the paleognathous genome architecture,with a higher transposon removal rate in tinamous than in ratites.One repeat family,AviRTE,likely underwent horizontal transfer from tropical parasites to the ancestor of little and undulated tinamous about 30 million years ago.Our analysis of gene families identified rapid turnover of immune and reproductionrelated genes but found no evidence of gene family changes underlying the convergent evolution of flightlessness among ratites.We also found that mitochondrial genes have experienced a faster evolutionary rate in tinamous than in ratites,with the former also showing more degenerated W chromosomes.This result can be explained by the Hill-Robertson interference affecting genetically linked W chromosomes and mitochondria.Overall,we reconstructed the evolutionary history of the Palaeognathae populations,genes,and TEs.Our findings of co-evolution between mitochondria and W chromosomes highlight the key difference in genome evolution between species with ZW sex chromosomes and those with XY sex chromosomes.展开更多
基金This work was supported by the Qinchuangyuan Project of Shaanxi Province,China(QCYRCXM-2022-145)the Major Project of the Key Research Base of Humanities and Social Sciences of the Ministry of Education,China(22JJD790052)+1 种基金the Chinese Universities Scientific Fund(Z1010422003)the National Natural Science Foundation of China(72373117).
文摘With increasing population and changing demographics,food consumption has experienced a significant transition in quantity and quality.However,a dearth of knowledge remains regarding its environmental impacts and how it responds to demographic dynamics,particularly in emerging economies like China.Using the two-stage Quadratic Almost Demand System(QUAIDS)model,this study empirically examines the impact of demographic dynamics on food consumption and its environmental outcomes based on the provincial data from 2000 to 2020 in China.Under various scenarios,according to changes in demographics,we extend our analysis to project the long-term trend of food consumption and its environmental impacts,including greenhouse gas(GHG)emissions,water footprint(WF),and land appropriation(LA).The results reveal that an increase in the proportion of senior people significantly decreases the consumption of grain and livestock meat and increases the consumption of poultry,egg,and aquatic products,particularly for urban residents.Moreover,an increase in the proportion of males in the population leads to higher consumption of poultry and aquatic products.Correspondingly,in the current scenario of an increased aging population and sex ratio,it is anticipated that GHG emissions,WF,and LA are likely to decrease by 1.37,2.52,and 3.56%,respectively.More importantly,in the scenario adhering to the standards of nutritional intake according to the Dietary Guidelines for Chinese Residents in 2022,GHG emissions,WF,and LA in urban areas would increase by 12.78,20.94,and 18.32%,respectively.Our findings suggest that changing demographics should be considered when designing policies to mitigate the diet-environment-health trilemma and achieve sustainable food consumption.
基金supported by the National Key R&D Program of China(2020YFC2003102).
文摘Objective:To reveal the distribution characteristics and demographic factors of traditional Chinese medicine(TCM)constitution among elderly individuals in China.Methods: Elderly individuals from seven regions in China were selected as samples in this study using a multistage cluster random sampling method.The basic information questionnaire and Constitution in Chinese Medicine Questionnaire(Elderly Edition)were used.Descriptive statistical analysis,chi-squared tests,and binary logistic regression analysis were used.Results: The single balanced constitution(BC)accounted for 23.9%.The results of the major TCM constitution types showed that BC(43.2%)accounted for the largest proportion and unbalanced constitutions ranged from 0.9%to 15.7%.East China region(odds ratio[OR]=2.097;95%confidence interval[CI],1.912 to 2.301),married status(OR=1.341;95%CI,1.235 to 1.457),and managers(OR=1.254;95%CI,1.044 to 1.505)were significantly associated with BC.Age>70 years was associated with qi-deficiency constitution and blood stasis constitution(BSC).Female sex was significantly associated with yang-deficiency constitution(OR=1.646;95%CI,1.52 to 1.782).Southwest region was significantly associated with phlegm-dampness constitution(OR=1.809;95%CI,1.569 to 2.086).North China region was significantly associated with inherited special constitution(OR=2.521;95%CI,1.569 to 4.05).South China region(OR=2.741;95%CI,1.997 to 1.3.763),Central China region(OR=8.889;95%CI,6.676 to 11.835),senior middle school education(OR=2.442;95%CI,1.932 to 3.088),and managers(OR=1.804;95%CI,1.21 to 2.69)were significantly associated with BSC.Conclusions: This study defined the distribution characteristics and demographic factors of TCM constitution in the elderly population.Adjusting and improving unbalanced constitutions,which are correlated with diseases,can help promote healthy aging through the scientific management of these demographic factors.
文摘“Human-elephant conflict(HEC)”,the alarming issue,in present day context has attracted the attention of environmentalists and policy makers.The rising conflict between human beings and wild elephants is common in Buxa Tiger Reserve(BTR)and its adjoining area in West Bengal State,India,making the area volatile.People’s attitudes towards elephant conservation activity are very crucial to get rid of HEC,because people’s proximity with wild elephants’habitat can trigger the occurrence of HEC.The aim of this study is to conduct an in-depth investigation about the association of people’s attitudes towards HEC with their locational,demographic,and socio-economic characteristics in BTR and its adjoining area by using Pearson’s bivariate chi-square test and binary logistic regression analysis.BTR is one of the constituent parts of Eastern Doors Elephant Reserve(EDER).We interviewed 500 respondents to understand their perceptions to HEC and investigated their locational,demographic,and socio-economic characteristics including location of village,gender,age,ethnicity,religion,caste,poverty level,education level,primary occupation,secondary occupation,household type,and source of firewood.The results indicate that respondents who are living in enclave forest villages(EFVs),peripheral forest villages(PFVs),corridor village(CVs),or forest and corridor villages(FCVs),mainly males,at the age of 18–48 years old,engaged with agriculture occupation,and living in kancha and mixed houses,have more likelihood to witness HEC.Besides,respondents who are illiterate or at primary education level are more likely to regard elephant as a main problematic animal around their villages and refuse to participate in elephant conservation activity.For the sake of a sustainable environment for both human beings and wildlife,people’s attitudes towards elephants must be friendly in a more prudent way,so that the two communities can live in harmony.
文摘BACKGROUND The Limb Lengthening and Reconstruction Society(LLRS)is a premier orthopedic specialty organization that promotes limb reconstruction for all ages.LLRS membership characteristics,however,are poorly reported.This study delineates orthopedic surgeon LLRS members’demographic traits,academic achievement,leadership attainment,and geographical distribution across the United States.AIM To inform aspiring orthopedic professionals,as well as to promote growth and diversity in both the LLRS organization and overarching field.METHODS This cross-sectional study examined United States LLRS members’academic,leadership,demographic,and geographical attributes.After reviewing the 2023 LLRS member directory,Google search results were matched to the listings and appended to the compiled data.Sex and ethnicity were evaluated visually utilizing retrieved images.The Hirsch index(H-index)of academic activity,residency and fellowship training,other graduate degrees,leadership positions,practice type(academic or non-academic),and spoken languages were categorized.LLRS members per state and capita determined geographic distribution.The Mann Whitney U test was applied to compare H-index between males and females,as well as to assess member differences pertaining to affiliation with academic vs non-academic practice facilities.RESULTS The study included 101 orthopedic surgeons,78(77.23%)Caucasian and 23(22.77%)non-Caucasian,79(78.22%)male and 22(21.78%)female.Surgeons with DO degrees comprised only 3.96%(4)of the cohort,while the vast majority held MDs[96.04%(97)].Mean H-index was 10.55,with male surgeons having a significantly higher score(P=0.002).Most orthopedic surgeons(88.12%,)practiced in academic centers.Of those professionals who occupied leadership positions,14%were women,while 86%were men.Additionally,19(37.25%)United States regions and the District of Columbia lacked an LLRS-member orthopedic surgeon.Total per capita rate across the United States was 0.30 LLRS orthopedic surgeons per 1 million people.CONCLUSION Over 21%of LLRS members are women,surpassing prior benchmarks noted in orthopedic faculty reporting.LLRS members’high research productivity scores imply field dedication that can refine expertise in the limb lengthening and reconstruction space.Gender disparities in leadership remain,however,necessitating greater equity efforts.A low rate of LLRS representation per capita must be addressed geographically as well,to affect improvements in regional care access.This study can serve to support aspiring orthopedic professionals,inform diversity,leadership,and field advancement strategies,and maintain the continued goal of enhanced patient care worldwide.
文摘Background: In Sub-Saharan Africa, pre-eclampsia remains a major health problem contributing to high rates of maternal mortality. Despite this condition having adverse effects on maternal and child health, its prevalence and associated risk factors are still significant, especially in developing countries including Ghana. This study aimed to assess the prevalence and demographic distributions associated with pre-eclampsia among pregnant women at the Ho Teaching Hospital. Methods: A facility-based retrospective study was conducted by reviewing available data or hospital records of pregnant mothers admitted to the labor and maternity wards from January 2018 to December 2020. All pregnant women who were diagnosed with pre-eclampsia within this period were included in the study. The data were collected using a structured checklist. Results: 5609 data on pregnant women from 2018 to 2020 were recorded. Out of the 5609 data recorded, 314 pre-eclampsia cases were recorded giving an overall prevalence of 5.6%. The yearly prevalence for 2018, 2019, and 2020 were 4.6%, 5.6%, and 6.6%, respectively. The most recorded pre-eclampsia cases were seen among women within the age group of 18 - 24 years. The data showed that 112 (35.7%) of the pregnant women who had pre-eclampsia were nulliparous. Pre-eclampsia-associated maternal and fetal complications were;preterm delivery 221 (70.4%), intrauterine fetal death 62 (19.7%), eclampsia 9 (2.9%), HELLP syndrome 5 (1.6%) and maternal death 17 (5.4%). Associated factors of pre-eclampsia were parity, level of education, and occupation (p ≤ 0.05). Conclusion: The findings of this study showed a rising trend in the incidence of pre-eclampsia over the years at the Ho Teaching Hospital. Parity, level of education, and occupation were found to be associated with developing pre-eclampsia.
文摘Globally,population dynamics are shifting towards increased life expectancy,and many countries,including Greece,face significant demographic challenges.Greece is particularly impacted by one of the lowest birth rates in the world and a rapidly aging population.This demographic shift places unprecedented pressure on the nation’s pension systems and economic stability,as more people retire than enter the workforce.This study aims to explore the historical factors contributing to Greece’s demographic situation,analyze the consequences of current trends,and propose strategic solutions.The research utilizes a literature review approach and the case study of Greece to understand the depth and breadth of the demographic crisis.Key areas of focus include the declining birth rate,the economic implications of an aging population,and the potential of migration and policy reform to rejuvenate demographic dynamics.The study evaluates various policy interventions from other countries to propose a tailored,multi-faceted strategy for Greece.These strategies emphasize economic incentives for young families,improved childcare and parental support,healthcare investment,and inclusive migration policies to enhance workforce numbers.This comprehensive approach seeks to provide actionable insights that can help Greece mitigate the effects of demographic decline and foster a more sustainable future,aligning policy interventions with socio-economic and cultural realities.
文摘The decline in the birth rate,which has been uninterrupted in Italy since the mid-1960s,has had a significant impact on many aspects of society.As far as the educational system is concerned,this phenomenon has acted like a wave,first causing a decline in the population of the first school age groups,then in the other groups,until recently affecting the 19-25 age group,which includes the majority of university students.As a result,the majority of Italian universities have seen a decline over time in both enrollments(matriculations)and student numbers(enrollments),although the situation varies from one area to another.In the Mezzogiorno,this trend is even more pronounced,since an increasing number of resident students tend to favor universities in the Centre-North,creating a South-Centre-North movement,which could be compared to a particular form of cultural tourism,without a similar flow in the opposite direction.Finally,the study highlights the probable consequences of the recent demographic depopulation on the future trend of university enrollment of residents aged 19-25 in the Calabria region,using the most recent demographic projections of Istat and constructing two evolutionary scenarios.In the first scenario,we have assumed that in the near future university enrollment rates remain constant throughout the period considered;in the second scenario,these rates instead experience a gradual and continuous increase.These results could be useful if further forecasts of university enrollments were to be made at the level of individual Calabrian universities.
文摘Background: Autosomal dominant polycystic kidney disease (ADPKD) is an important etiological factor causing chronic kidney disease (CKD), cardiovascular diseases and hypertension (HT). The purpose of the present study is to investigate the clinical information and demographic characteristics of autosomal dominant polycystic kidney disease patients who received treatment at our hospital for the last five years. Material and Method: Among 21400 people who sought care at Siirt State Hospital Urology and Nephrology Outpatient Clinics between January 2015 and January 2020 for various reasons, a total of 36 patients experiencing autosomal dominant polycystic kidney disease were included in the present research. Retrospective patient file access was used to gather demographic information and laboratory data. Results: The study included 36 patients in all, 25 (69.4%) male and 11 (30.6%) female. The patient’s average age was 50.8 ± 19.0. The average age at diagnosis was 43.4 ± 17.2. Family history was positive in 29 (80.5%) of the patients. There were hypertension in 27 (75.0%) patients, coronary artery disease in five (13.9%) patients, diabetes mellitus in five (13.9%) patients, left ventricular hypertrophy in 18 (50%) patients, proteinuria in 11 (30.6%) patients, and six (16.7%) patients had macroscopic hematuria. Liver cysts were found in 23 (63.9%) of the patients and nephrolithiasis in eight (22.2%). Discussion: Hypertension is the most common finding when clinical and demographic data of autosomal dominant polycystic kidney disease are examined. Providing blood pressure control reduces the risk of death due to left ventricular hypertrophy and slows down the rate at which chronic kidney disease progresses. The rate was found to be 80.5% for patients with a positive family history. It may be possible to diagnose and treat people with autosomal dominant polycystic kidney disease earlier by screening their family members.
文摘China needs a proactive response to negative population growth The year 2022 will most likely be remembered as a turning point in any future discussion on China’s demographics.That year,the world’s most populous country entered an“era of negative population growth.”Its natural population growth rate slid to 0.6 per thousand from 2021’s 0.34 per thousand,the nation’s overall population declined by 850,000 people year-on-year,and new births fell below 10 million for the first time since 1950,data from the National Bureau of Statistics showed.
文摘A great discovery made by H. von Foerster, P. M. Mora and L. W. Amiot was published in a 1960 issue of “Science”. The authors showed that existing data for calculating the Earth’s population in the new era (from 1 to 1958) could be described with incredibly high proximity by a hyperbolic function with the point of singularity on 13 November 2026. Thus, empirical regularity of the rise of the human population was established, which was marked by explosive demographic growth in the 20<sup>th</sup> century when during only one century it almost quadrupled: from 1.656 billion in 1900 to 6.144 billion in 2000. Nowadays, the world population has already overcome 7.8 billion people. Immediately after 1960, an active search for phenomenological models began to explain the mechanism of the hyperbolic population growth and the following demographic transition designed to stabilize its population. A significant role in explaining the mechanism of the hyperbolic growth of the world population was played by S. Kuznets (1960) and E. Boserup (1965), who found out that the rates of technological progress historically increased in proportion to the Earth’s population. It meant that the growth of the population led to raising the level of life-supporting technologies, and the latter in its turn enlarged the carrying capacity of the Earth, making it possible for the world population to expand. Proceeding from the information imperative, we have developed the model of the demographic dynamics for the 21<sup>st</sup> century for the first time. The model shows that with the development and spread of Intelligent Machines (IM), the number of the world population reaching a certain maximum will then irreversibly decline. Human depopulation will largely touch upon the most developed countries, where IM is used intensively nowadays. Until a certain moment in time, this depopulation in developed countries will be compensated by the explosive growth of the population in African countries located south of the Sahara. Calculations in our model reveal that the peak of the human population of 8.52 billion people will be reached in 2050, then it will irreversibly go down to 7.9 billion people by 2100, if developed countries do not take timely effective measures to overcome the process of information depopulation.
文摘Given the great strides that China's education sector has made in recent decades, it can be expected that the overall workforce quality of exiting China's labor market in coming one or two decades will be relatively low, while the overall quality of workforce newly entering into China's labor market will be high. As the new, bettereducated generation takes over, China's workforce quality will be vastly improved. This in turn will promote economic growth. We refer to economic growth arising from improved workforce quality as qualitative demographic dividend. Using the computable general equilibrium (CGE) model, this paper investigates the relationship between workforce quality improvements and economic growth. According to the model's results, an improvement in workforce quality will raise the economic growth rate by about two percentage points per annum between 2016 and 2020 and by 10 percentage points cumulatively by 2020. In other words, GDP will be 1.1 times the level of baseline GDP by 2020 due to the improved education levels. Given different production functions across sectors, the improvement of workforce quality will affect different sectors in different ways. On the whole, the improvement of workforce quality is more favorable to the development of capital-intensive sectors and sectors with rapid technology progress. According to this paper, considering the improvement of workforce quality, we cannot conclude that China's potential economic growth rate has already begun to decline. Despite diminishing conventional quantitative demographic dividends, China "s qualitative demographic dividends will keep rising. Qualitative demographic dividends will further push forward China's industrial restructuring and the strategic transition of industrial competitiveness from quantitative to qualitative and from an extensive to an intensive pattern of development.
基金Supported by the National Social Science Fund of China(13XSH017)~~
文摘[Objective] The aim was to analyze the phenomenon of employment diffi- culty and labor shortage, and to reveal the influencing factors of employment difli- culty and labor shortage. [Method] On the basis of the economic principle of popu- lation dividend, the use of human resources and natural resource constraints The IS-LM model describes these two states. [Results] The resource constraints have a "squeeze" effect on the demographic dividend, and employment pressure is shown in terms of the population opportunity window; the labor market segmentation, the ir- rational industrial structure, the backward curriculum and employment concept are the main factors affecting employment and labor shortage. [Conclusion] The way to solve this dilemma must be removed from the division of labor market, the adjust- ment of industrial structure, the setting of university specialty, the change of em- ployment concept of university graduates as well as the improvement of the quality of labor.
文摘This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the direction of demographic transition and whether or not it has finished. Apart from establishing new theories of demographic transition and the trasition of demographic structure, this paper differentiates the concepts of "relative surplus population" and "relative suitable population," and "relative insufficient population" and identifies key demographic differences along the way. In doing so, this paper argues that China's demographic strueture is undergoing a process of rebalancing.
基金supported by the National Natural Science Foundation of China [No.81172680]
文摘Worldwide, the incidence of birth defects in low-income countries is 6.42%, while in middle-income and high-income countries it is 5.57% and 4.72%, respectively;approximately 303, 000 newborns die from birth defects each year. In China, the incidence of birth defects is about 5.6%, and around 8.14 million people have congenital disabilities, accounting for 9.6% of total disabled people[1]. Birth defect remains a major clinical and public health challenge because of its high fatality rate and protracted and severe sequela.
文摘To identify the determinant of the occurrence of IUD expulsion Materials & Methods Based on 25 733 IUD uses from the Chinese Two per Thousand Fertility Survey data, this study examines the patterns and differentials of IUD expulsion rate by characteristics of women, and identifies the socio demographic determinants of IUD expulsion. A Life Table method was used to calculate the cumulative expulsion rate and a random effects discrete time survival model was employed to assess the impact of potential determinants simultaneously on the risk of expelling an IUD. Results Three major findings are observed in this study. First, IUD expulsion was the second main reason, after pregnancy during IUD use, for IUD discontinuation during the first four years of IUD insertion; the expulsion rates were 6.4%, 9.1%, 10.8 %, and 12.0% at 12, 24, 36 and 48 months, respectively. Second, there was a clustering of IUD expulsion: some women experienced repeated IUD expulsions. Third, some socio demographic characteristics and fertility history were associated with the occurrence of IUD expulsion. In particular, the expulsion rate was high among young women, among those with two or more children and among those living in rural areas. Conclusion The above mentioned factors shoald be addressed in order to decrease the IUD expulsion rate and enhance the reprocluctive he alth of women.
基金supported by Independent Inovation Foundation of Shandong Univercity,IIFSDU
文摘The objective of social development is to construct a harmonious society.In China,the key to a harmonious society is the happiness of more than 900 million farmers living in the rural areas.This study aimed to measure rural residents' subjective well-being(SWB) through the day reconstruction method,as well as to analyze SWB's influencing factors through a variety of statistical methods.The results showed that the average U index was 12.79%,indicating that respondents were unhappy 12.79% of the time.Twenty-seven percent of the population had a U index greater than 0,with the average value being 47%,indicating that these people were unhappy 47% of the time.The study also found that SWB varied according to the characteristics of the respondents.Logistic regression analysis showed that social and demographic factors,including age,education,county,household size,generation number,per capita income,migration status and social networking,which significantly affected rural residents' SWB.The size of the impact varied with the different factors.
基金financial support from the National Natural Science Foundation of China(71273009)pUSDA,Economic Research Service,Cooperative Agreement(58-3000-7-0060)+2 种基金USDA,the Agricultural Food Research Initiative of the National Institute of Food and Agriculture(2010-65400-20489)USDA,Foreign Agricultural Service,th Emerging Markets Program Grant(2010-72)Chinese Universities Scientific Fund(2014RC017)
文摘Drawn on the data collected by surveying 1 340 urban households from six cities in China, this paper estimates the impacts of demographic structure and population aging on household meat consumption, by jointly considering meat consumed at home and away from home. Based on the trajectories of population, a simple simulation on meat demand trend in China is conducted subsequently. The results suggest: 1) Meat consumed away from home averagely accounts for near 30% of household total meat consumption in terms of quantity, so that its omission likely leads to a significant underestimate of total meat consumption and misunderstanding the driving forces; 2) population aging significantly and negatively affects per capita meat consumption, suggesting that the expected meat demand in China without considering population aging will be overestimated. The findings from this study have important implications for better understanding the relative issues on China's meat consumption under the situation of population aging.
基金support of the U.S.National Science Foundation (awards 8206992,8906869,9405933,9909947,0948585 to S.P.Hubbell)the John D.and Catherine D.McArthur Foundationthe Smithsonian Tropical Research Institute
文摘Background: The first three censuses of the 50-ha plot at Barro Colorado Island spanned an unusually harsh dry season during the 1983 El Nitro. By the early 1990s, we had documented increases in tree mortality, tree growth, and large population fluctuations of many species during the 1982-1985 census interval. At the time, we asserted that increasing drought frequency would greatly affect the forest. With the benefit of five more censuses at Barro Colorado from 1995-2015, we can now put the 1980 conditions in a longer perspective and test the hypothesis that increasing droughtiness has continued to change the forest. Methods: A 50-ha forest plot on Barro Colorado Island was censused eight times, in 1982 and every five years since 1985. All free-standing woody stems were measured, mapped, and identified in each census. Results: 1) The period 1982-1992 included several extreme dry seasons, not just 1983, but since then there have been few such droughts. 2) Dbh growth declined from a peak in the early 1980s to its lowest in the early 1990s. From 1995-2015 it increased slightly, but not returning to the initial peak. Nearly every species and all dbh categories followed the same pattern. 3) The elevated stand-wide mortality rate of large trees during the 1982-1985 drought has not returned, and most individual species showed the same pattern of elevated mortality in the 1980s followed by low and fairly stable mortality after 1990. 4) Sapling mortality declined after 198,5, but rose again in the late-90s, so the 1980s drought period no longer looks unusual. Mortality of individual species' saplings fluctuated erratically, including cases where mortality during the drought was lower than after. 5) Population sizes of individual species fluctuated in all possible directions. Some species declined precipitously during the drought, then recovered, but others did not recover. Other species increased in abundance during the drought. Conclusions" Droughts of the 1980s elevated tree growth and mortality at Barro Colorado, but since 1990, demographic rates have remained lower, paralleling a moderate climate with few severe droughts after 1990. Moisture-demanding species suffered during the drought, but many have since recovered. We do not know how often such drought periods recur. Moreover, many species' abundances fluctuated over 35 years with no known cause.
文摘Is China able to maintain fast growth after three decades? This paper tries to answer this question by: 1) arguing that factors contributed to sustained long-run growth at supply side;2) focusing on contributions of demographic dividend especially that of rural-urban migration;and 3) analyzing rural demographic change with information collected through village-wide household survey.Policy alternatives to realize remaining potential demographic dividend are proposed based on the analysis of changing rural demographic structure.
基金This study was supported by the National Natural Science Foundation of China(31671319,31722050,32061130208)Natural Science Foundation of Zhejiang Province(LD19C190001)+5 种基金European Research Council Starting Grant(grant agreement 677696)to Q.Z.the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31020000,XDB13000000)International Partnership Program of Chinese Academy of Sciences(152453KYSB20170002)Carlsberg Foundation(CF16-0663)Villum Foundation(25900)to G.J.ZWe thank China National Genebank at BGI for contributing to the sequencing.We would like to thank Christopher C.Witt,Mariel L.Campbell and Ariel M.Gaffney from the Museum of Southwestern Biology,Gary Graves from Smithsonian Institute,Robb T.Brumfield and Donna L.Dittman from Louisiana State University Museum of Natural Science,Jack Withrow and Andy Kratter from Florida Museum of Natural History,University of New Mexico for providing bird DNA samples for this work.
文摘Palaeognathae includes ratite and tinamou species that are important for understanding early avian evolution.Here,we analyzed the whole-genome sequences of 15 paleognathous species to infer their demographic histories,which are presently unknown.We found that most species showed a reduction of population size since the beginning of the last glacial period,except for those species distributed in Australasia and in the far south of South America.Different degrees of contraction and expansion of transposable elements(TE)have shaped the paleognathous genome architecture,with a higher transposon removal rate in tinamous than in ratites.One repeat family,AviRTE,likely underwent horizontal transfer from tropical parasites to the ancestor of little and undulated tinamous about 30 million years ago.Our analysis of gene families identified rapid turnover of immune and reproductionrelated genes but found no evidence of gene family changes underlying the convergent evolution of flightlessness among ratites.We also found that mitochondrial genes have experienced a faster evolutionary rate in tinamous than in ratites,with the former also showing more degenerated W chromosomes.This result can be explained by the Hill-Robertson interference affecting genetically linked W chromosomes and mitochondria.Overall,we reconstructed the evolutionary history of the Palaeognathae populations,genes,and TEs.Our findings of co-evolution between mitochondria and W chromosomes highlight the key difference in genome evolution between species with ZW sex chromosomes and those with XY sex chromosomes.