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At least 127 records · Page 7Linked to original sources
PubMed2003

Modeling momentum in gradual demographic transitions.

The analysis of population momentum following a gradual decline in fertility to replacement level provides valuable insights into prospects for future population growth. Here, we extend recent work in the area by applying a new form of the quadratic hyperstable (QH) model, which relates exponentially changing fertility to the resultant exponentiated quadratic birth sequence. Modeling gradual transitions from an initial stable population to an ultimate stationary population indicates that such declines in fertility increase momentum by a product of two factors. The first factor is a previously noted continuation of stable growth for half the period of decline. The second is a not previously appreciated offsetting factor that reflects the interaction between the decline in fertility, the changing age pattern of fertility, and the changing age composition of the population. Numerical examples using both hypothetical and actual populations demonstrate that for declines of any length, the product of the two factors yields momentum values that closely agree with the results of population projections. The QH model can examine monotonic transitions between any two sets of constant vital rates. As a generalization of the fixed-rate stable model, it has great potential value in numerous areas of demographic analysis.

Birth Rate↗
PubMedDate not supplied

An evolutionary ecological perspective on demographic transitions: modeling multiple currencies.

Life history theory postulates tradeoffs of current versus future reproduction; today women face evolutionarily novel versions of these tradeoffs. Optimal age at first birth is the result of tradeoffs in fertility and mortality; ceteris paribus, early reproduction is advantageous. Yet modern women in developed nations experience relatively late first births; they appear to be trading off socioeconomic status and the paths to raised SES, education and work, against early fertility. Here, [1] using delineating parameter values drawn from data in the literature, we model these tradeoffs to determine how much socioeconomic advantage will compensate for delayed first births and lower lifetime fertility; and [2] we examine the effects of work and education on women's lifetime and age-specific fertility using data from seven cohorts in the Panel Study of Income Dynamics (PSID).

Adolescent↗
PubMed2006

Urbanization and obesity in The Gambia: a country in the early stages of the demographic transition.

OBJECTIVE: To investigate the distribution of overweight and obesity and its relationship with socio-economic and behavioural factors in a developing-country population undergoing rapid nutritional transition. DESIGN: Cross-sectional house-to-house survey in urban Gambia. SUBJECTS: Four groups of 50 subjects were sampled as follows: young men (YM, 14-25 years), young women (YW, 14-25 years), older men (OM, 35-50 years) and older women (OW, 35-50 years). MEASUREMENTS: Several socio-economic and behavioural factors were investigated. Composite indices for socio-economic status, education, healthy lifestyle and western influences were created. Body weight, height, waist and hip circumferences were measured and body mass index (BMI) was calculated. Body composition was assessed by leg-to-leg bioimpedance. Overweight was defined as BMI=25.0-29.9 kg/m(2) and obesity as BMI>or=30.0 kg/m(2). RESULTS: There were highly significant gender and age differences in overweight (YM=0%, YW=10%, OM=6% and OW=34%) and obesity (YM=0%, YW=4%, OM=6% and OW=50%). Only 16% of OW were neither overweight nor obese compared to 88% of OM. OW had a higher fat mass percent (38.4%) than other groups, while fat-free mass (kg) was significantly higher in males than females with YW having the lowest value. Young generations were more educated and more influenced by western ideals than OM and OW. Weight gain was not always associated with weight concern and many overweight/obese subjects did not perceive themselves as overweight. CONCLUSION: Social and behavioural changes are already creating a perceptible 'generational gap' among this population undergoing rapid transition. The improved education and current lean status of the younger adults offers opportunities for preventative interventions. These need to be specially targeted at women.

Adolescent↗
PubMed2002

Demographic transition of the Swedish cystic fibrosis community--results of modern care.

Assessing the results of modern cystic fibrosis (CF)-care and estimating the future population and its demography is important to evaluate the treatment regimens and to calculate the future needs of health-care resources. This paper updates previous incidence calculations. It assesses the results of modern CF-care in terms of survival and changing demography in Sweden. The incidence of CF in Sweden was calculated as 1/5600 live-births. Of the CF-population alive in 1999, 45% were > or = 18 years old. The mean annual mortality rate since 1991 was 0.9% (+/-0.4) and the median age at death 26 years (range 0-72). Of those born > or = 1991, 95% were estimated to survive their 25th birthday. The incidence of CF in Sweden is low. Modern CF-care in Sweden shows good results. The CF-population is growing rapidly and the adult part of the population will soon be larger than the paediatric. Continuously adapted resources are required to assure the future treatment quality especially for the growing adult CF-population.

Adolescent↗