Some extensions of the keyfitz momentum relationship

A stable population, such that the total birthrateB(t) =B _o e ^ro^t, is abruptly altered by modifying the age-specific birth rate,m(x). The survivor function remains unaltered. The modified population ultimately settles down to a stable behavior, such thatB(t) =B ₁ e ^r ₁ ^t . It is shown thatB ₁/B ₀ = (R ₀ ?R ₁)/[(r ₀ ?r ₁)R ₀ Z ₁], whereR ₀,R ₁ are the net reproduction rates before and after the change, and \(\bar Z_1 \) expected age giving birth for the stable population after the change. The age structure and transients resulting from the change are also described. The effect of an abrupt change in the survivor functionl(x) is also investigated for the simple case where the change is caused by alteringl(x) toe ^?λx l(x). It is shown that the above ratio becomes \(B_1 /B_0 = N_1 /N_0 = [1 - \smallint _0^\infty e^{ - kx} g(x)dx]/\bar Z_1 \lambda \) , whereN refers to the numbers in the population,k =r ₀ + λ, andg(x) =m(x)l(x), the value before the change. A measure for the reproductive worth of the population is also established.     

Counter-Examples about Lower- and Upper-Bounded Population Growth

ABSTRACT

For a unimodal growth function f having its maximum at a critical state x _c , the interval bounding the population size asymptotically is usually presented as being equal to [f ^○2(x _c ), f(x _c )]. This interval however does not represent the maximum range within which the population size can vary, even asymptotically. The actual invariant interval containing the population size is equal to: [min(x*, f ^○2(x _c )), f(x _c )], where x* denotes the non-zero fixed point, assumed to be unique, of the iteration of f.     

Emotional wellbeing of student midwives during COVID-19

BackgroundMental health of students in higher education was affected during the COVID-19 pandemic.AimTo examine the emotional wellbeing of midwifery students in the Netherlands and Flanders (Belgium) during COVID-19.MethodsA cross-sectional online-based survey with 619 Dutch and Flemish midwifery students. Sociodemographic details were obtained. Anxiety and depression were measured twice (T1, T2) during the COVID-19 pandemic.FindingsFlemish students had significantly higher mean depression and anxiety scores than Dutch students during the total period of study (p < .001; p < .001). Total group mean depression and anxiety scores were significantly higher at T2 compared to T1 (p < .001; p < .001). In the Dutch student group, there was a significant increase of depression from T1 to T2 (p < .001). In the Flemish student group, both depression and anxiety scores significantly increased from T1 to T2 (p < .001; p < .001). A history of psychological problems predicted both depression and anxiety, irrespective of COVID-19 period or country (p < .001; p < .001). Being single (p.015) and having a job (p.046) predicted depression, irrespective of period or country. A history of psychological problems predicted depression (p.004; p < .001) and anxiety (p.003; p.001) during the total period of study. Being single also predicted depression during T2 (p.024).ConclusionThese findings inform how emotional wellbeing of midwifery students was affected during the COVID-19 pandemic and identify those students that might need extra attention after the pandemic, during another pandemic or similar situations with social restrictions.     

Are Father’s or Mother’s Socioeconomic Characteristics More Important Influences on Student Performance? Recent International Evidence

Since the early 1970s the importance of mothers’ socioeconomic characteristics on their children’s educational and occupational attainment has been acknowledged. However, it is not clear if fathers’ characteristics have a stronger influence because men usually have stronger attachments to the labour market, or alternatively mothers’ characteristics are more important because of their greater role in children’s socialization. This study addresses this question by comparing the influence of father’s and mother’s education and occupation on student performance in literacy and numeracy using data from 30 countries. The impact of mother’s education is usually greater or comparable to that of father’s education. In contrast, substantially stronger effects for mother’s occupational status compared to father’s were rare. In most countries the impact of mother’s socioeconomic characteristics (education plus occupation) on student performance is comparable to that for father’s. Of the four indicators of socioeconomic background, father’s occupational status and mother’s educational attainment tend to have stronger effects, although many countries do not conform to this pattern. There are indications that the relative importance of mother’s characteristics have increased over time.

Child support and non-resident fathers’ contact with their children

The paper presents a model of a non-resident father’s child support and contact with his child, which combines the public good treatment of “child quality” with “trade” in father–child contact time in a setting of non-cooperative interaction. It predicts that father’s income and mother’s non-labour income should have exactly the same effect on the frequency of father–child contact if he chooses to make lump sum payments to the mother. If he does not or there is a binding child support payment order, they have effects opposite in direction. A higher binding support order reduces father–child contact but may well raise “child quality”.

Individual and institutional determinants of multidimensional poverty: A European comparison

In this article we evaluate to what extent between-country differences in the probability of being ‘multidimensional’ poor can be explained by a range of ‘domain-specific’ indicators of welfare regime arrangements. To this end, a so-called micro-macro model is estimated, testing the ‘independent’ effect of institutions, as opposed to alternative explanations such as between-country differences in population composition and economic affluence. Although we conclude that institutional arrangements do influence the risk of multidimensional poverty in the expected direction, we also find that bringing the ‘economy’ back into the analyses has a non-trivial impact. Our results point at several avenues for further discussion and research. First, although the more elaborate welfare regimes generally do a better job in preventing poverty, the level of transfers is not always ‘proportional’ to the general standard of living in these countries. Second, we only find partial confirmation for the often cited ‘negative’ impact of labour market flexibility and the related equality-jobs trade-off. While stricter employment regulations do reduce the poverty risk (be it only after controlling for economic affluence), flexibility in terms of the availability of fixed-term labour seems to be preferable to unemployment, even if at the individual level, labour market flexibility increases the likelihood of being poor quite severely.

Why does onlyAthalia Japonica enter summer diapause among three sympatricAthalia sawflies feeding on crucifers?

Summary This report assesses the primary factor for the evolution of summer diapause of the three species of sawfly,Athalia japonica, A. rosae andA. infumata that feed on cruciferous plants and coexist in the same area.A. japonica has two discrete spring and autumn generations, butA. rosae andA. infumata 5–6 generations. OnlyA. japonica enters summer diapause in response to the long daylengths in spring. Although these three sawflies usually feed on the same cultivated crucifers, they differ markedly in the utilization of wild crucifers. They oviposit only on young leaves.A. japonica mainly usesCardamine plants which sprout in spring and autumn.A. rosae andA. infumata primarily use hosts with new leaves all the year round, i.e. cultivated crucifers andRorippa indica, respectively. The thermal threshold for development is lower inA. japonica than in the other two species. The low heat tolerance ofA. japonica is adapted only to cool shady habitats whereCardamine grows. Presumably, summer diapause ofA. japonica is adaptation to the deterioration of the primary host plants rather than unfavorable climatic conditions. This interpretation is supported by the movement patterns of the threeAthalia sawflies, alternative means to escape from deteriorated habitat conditions.     

A comparative study of the searching efficiencies of a parasite and a hyperparasite

Summary The searching efficiencies of a primary parasite (Diaeretiella rapae (McIntosh)) and a hyperparasite (Alloxysta brassicae (Ash.)) were investigated and compared. In both species, at all parasite densities, there was a curvilinear relationship (P<0.001) between the number of hosts parasitised and the host density. A linear regression (loga=logQ−m logP) was fitted for log area of discovery against log parasite density (P<0.001). The area of discovery for its immediate (i.e. primary) host (viz.Diaeretiella for the hyperparasite and aphid forDiaeretiella) is lower in the hyperparasite than in the primary parasite. InDiaeretialla both the searching efficiency and the mutual interference constant increased (but not significantly,P>0.05) in the presence of its males.     

African-American and white inequality in the nineteenth century American South: a biological comparison

The use of height data to measure living standards is now a well-established method in economic history. By using a new source of nineteenth century Texas state prison records, the present study contrasts the heights of comparable blacks and whites between the Civil War and Reconstruction in the American South. White stature exceeded black stature. Between 1850 and 1870, black stature declined by more than 1 cm but recovered toward the end of the nineteenth century. Postbellum white stature declined by more than 1 1/2 cm over the same period yet never recovered.

Are there gender and country of origin differences in immigrant labor market outcomes across European destinations?

The 1994–2000 waves of the European Community Household Panel are used to study the earnings of immigrants as compared to native workers in 15 European countries. At the time of arrival, there is a significant negative partial effect of foreign birth on individual earnings compared to the native born in the destination of around 40%. These differences vary across origins and destinations and by gender. Immigrant earnings catch-up to those of the native born after around 18 years in the destination. Schooling matters more for earnings for women, whereas, language skills are relatively more important for men.

Imperfect goods and labor markets, and the union wage gap

Existing theoretical literature fails to explain satisfactorily the differences between the pay of workers who are covered by collective agreements and others who are not. This study aims at providing a model framework that is amenable to an analysis of this issue. Our general-equilibrium approach integrates a dual labor market and a two-sector product market. The results suggest that the so-called “union wage gap” is largely determined by the degree of centralization of the bargains and, to a somewhat lesser extent, by the expenditure share of the unionized sector's goods.

Strategic altruistic transfers and rent seeking within the family

This paper examines the rent-seeking behavior of “selfish” children in competing for parental transfers. The paper extends Chang and Weisman (South Econ J 71:821–836, 2005), that focuses on compensated transfers, to allow for non-compensated transfers à la Buchanan (J Law Econ 26:71–85, 1983) and derives results for the case in which children’s time contributions as perceived by their parents are a merit good (e.g., service), pure waste (e.g., bugging), or a mix of both. For an increase in the proportion of time contributions that are pure waste, parents find it optimal to reduce the size of an overall transfer, thereby lowering the levels of wasteful rent-seeking activities by their children within the family.

Adult population parameters and life tables of an epilachnine beetle (Coleoptera: Coccinellidae) feeding on bitter cucumber in Sumatra

Summary The population dynamics of an epilachnine beetle, which is closely related toEpilachna sparsa Dieke (henceforth called “sp. C”) and feeds on bitter cucumberMomordica charantia, was studied by mark-recapture of adults and the construction of life tables. The study was repeated three times, i.e., March–May, July–September and October–December in 1982, in Padang, Sumatra, Indonesia. After the establishment of the host plants, adults of “sp. C” soon colonized, and each study period ended in the death of the plants due to defoliation by the larvae and adults. The estimated mean length of residence of adults ranged from 6–11 days, but this was probably much shorter than the actual longevity, because the adults were so active that they flew away, or dropped off the plants, when they were approached or slightly disturbed. Life tables indicated that egg mortality ranged from 17.8–53.9%, and a parasitic waspTetrastichus sp. B made up 41.1–64.2% of egg mortality. Two wasps,Tetrastichus sp. C andPediobius foveolatus killed 1.2–19.4% (7.6–100%)^* of 4th instars and only the latter species attacked the pupae, killing 24.6–59.1% (45.1–72.4%). Parasitism and starvation by overcrowding contributed most to the total mortality from egg to adult emergence, which ranged from 89.4–99.5%. “Sp. C” had a higher diversity and level of parasitism than the Japanese species,E. vigintioctopunctata. The high dispersal power of “sp. C”, coupled with the prolongedl _x−m_x schedules shown under laboratory conditions, was advantageous for exploiting the food plant which was available throughout the year, but was rather patchily distributed in space.     

Determinants of business success: an examination of Asian-owned businesses in the USA

Using confidential microdata from the US Census Bureau, we investigate the performance of Asian-owned businesses. Using regression estimates and a special non-linear decomposition technique, we explore the role that class resources, such as financial capital and human capital, play in contributing to the relative success of Asian businesses. We find that Asian-owned businesses are more successful than white-owned businesses for two main reasons—Asian owners have high levels of human capital and their businesses have substantial start-up capital. Using detailed information on both the owner and the firm, we estimate the explanatory power of several additional factors.

Measuring longevity achievements under welfare interdependencies: a case for joint life expectancy indicators

Whereas period life expectancy constitutes an intuitive indicator of the survival conditions prevailing at a particular period, this paper argues that, given the existence of welfare interdependencies, that widespread indicator is nonetheless an incomplete measure of the longevity achievements relevant for human well-being. The central importance of coexistence for human-beings implies that usual life expectancy measures should be complemented by joint life expectancy indicators, which measure the average coexistence time under particular survival conditions. After a study of the theoretical foundations of ‘single’ and ‘joint’ life expectancy indicators, it is shown that joint life expectancy measures tend to enrich significantly the comparison of longevity achievements across countries and periods. Moreover, the introduction of joint life expectancy indicators—as a complement to conventional life expectancy measures—into multi-variable indexes such as the United Nations’ HDI is also shown to affect international rankings of standards of living to a non negligible extent.

How important is homeland education for refugees’ economic position in The Netherlands?

We use data on refugees admitted to The Netherlands that include registration of education in their homeland by immigration officers. Such data are seldom available. We investigate the quality and reliability of the registrations and then use them to assess effects on refugees’ economic position during the first 5 years after arrival. The most remarkable finding is the absence of returns to higher education.

Tests of four hypotheses on soldier production, by using wild colonies ofPheidole fervida F. Smith (Hymenoptera: Formicidae)

Following four hypotheses on the production of soldiers were tested in thePheidole fervida colonies collected in the natural field:

Understanding changes in Māori incomes and income inequality 1997–2003

This paper examines recent changes in weekly income levels and dispersion for Māori, New Zealand’s indigenous ethnic group. Changes in the Māori income distribution between 1997 and 2003 reflect rapid increases in economic growth and employment rate. A reduced proportion of people had zero or benefit-level incomes and a higher proportion had high incomes. Income inequality declined for working-aged Māori and was stable for employed Māori. The average income gap between Māori and Europeans declined. The increased Māori employment rate during this period was the single most important driver of changes in the Māori income distribution.

Combining Happines’s and Suffering in a Retrospective View of Anchor Periods in Life: A Differential Approach to Subjective Well-Being

The intersection of dimensions of subjective well-being (SWB) generates SWB types. We delineated SWB types by cross-tabulating happiness and suffering ratings that participants attributed to outstandingly meaningful periods in their life referred to as anchor periods. A sample of 499 older Israelis (age 58–94) was queried about two positive periods (the happiest, the most important) and two negative periods (the most miserable, the most difficult). A variety of variables discriminated between the more frequent congruous types of Happy (high happiness and low suffering) and Unhappy (low happiness and high suffering), but also presented the incongruous types of Inflated (high happiness and high suffering) and Deflated (low happiness and low suffering) as discriminable. Thus, women were more likely to be Inflated whereas men were more likely to be Deflated; low education related more to Happy in the happiest period and to Unhappy in the negative periods; present life satisfaction related more to Happy than to Unhappy in the positive, but not in the negative, periods; and Holocaust survivors were more likely to be Deflated and Unhappy in the negative, but not in the positive, periods. The study supported a differential perspective on SWB within people’s narratives of their lives. An erratum to this article is available at .     

The association between social support and postpartum depression in women: A cross sectional study

Background

Prevalence of postpartum depression is estimated to be about 10–15% worldwide. Many risk factors are supposed to play a role leading a new mother to maternal postpartum depression which can considerably affect the baby, mother, family and also the society.