Indirect Estimates of Total Fertility Rate Using Child Woman/Ratio: A Comparison with the Bogue-Palmore Method

Indirect estimation methodologies of the total fertility rate (TFR) have a long history within demography and have provided important techniques applied demographers can use when data is sparse or lacking. However new methodologies for approximating the total fertility rate have not been proposed in nearly 30 years. This study presents a novel method for indirectly approximating the total fertility rate using an algebraic rearrangement of the general fertility rate (GFR) through the known relationship between GFR and TFR. It then compares the proposed method to the well-known Bogue-Palmore method. These methods are compared in 196 countries and include overall errors as well as characteristics of the countries that contribute to fertility behavior. Additionally, these methods were compared geographically to find any geographical patterns. We find this novel method is not only simpler than the Bogue-Palmore method, requiring fewer data inputs, but also has reduced algebraic and absolute errors when compared with the Bogue-Palmore method and specifically outperforms the Bogue-Palmore method in developing countries. We find that our novel method may be useful estimation procedure for demographers.     

Measuring potential fertility through null segments: an exploratory analysis

The demographic effectiveness of a family planning program must measure the difference between actual fertility and the "gross" potential fertility, i.e., the natural fertility which would have been achieved without use of contraception. The various methods of measuring "gross" fertility which have been used are described. It is understood that users of contraception are never a random sampling of the general population; they tend to be higher in fecundability and lower in proportion of sterile. For this reason, the best strategm of measurement involves utilization of preacceptance fertility rates over some given period of time among those reporting no contraceptive usage during that period. A procedure of measurement is proposed whereby natural fecundability is estimated from null segments. Possible biases are taken into account. Application of the method is made to 2 sets of data collected in Taiwan. Results of the application of the method to the Taiwanese data are tabulated. Fecundability functions derived from unrestricted null segments are different from those constructed from restricted subsets of "closed" null segments. Choice of whether to use restricted or unrestricted null segments will depend on the nature of the data available.     

Recursive Residuals for Multivariate Field Processes

Vector recursive residuals are developed for multivariate regression models on a field. A vector response variable is observed at points on a rectangular grid, together with regression variables measured at the same points. Neighbouring values of the response vector may be correlated and simple models are considered using a direct product structure for the variance matrix. Subsequent to obtaining vector recursive residuals principal component analysis is applied to obtain an evaluation of any changes that may be occurring in the regression relationship over the field. The method is then applied to the problem of detecting zones of bush fire damage and recovery from LANDSAT data.     

The relationship between ram sperm head morphometry and fertility depends on the procedures of acquisition and analysis used

Sperm head morphometry is a parameter in the evaluation of semen that has been associated with fertility in two ways: comparing morphometric measures between predefined groups of fertility; or analyzing morphometric data by multivariate techniques to identify cell populations. We analyzed the morphometry of ram sperm head by three procedures and checked its relationship with male fertility. A Computer-Aided Sperm Morphometric Assessment procedure (CASMA), an image analysis software (NIS-Elements) in combination with an optical microscope (MO-NIS) and this image analysis software in combination with a scanning electron microscope (SEM-NIS) were used. Eight morphometric parameters were assessed: length, width, area, perimeter, ellipticity, form factor, elongation and regularity. We observed significant differences between the morphometric data of sperm head obtained with three study procedures. The CASMA procedure shows the highest values for all parameters and the SEM-NIS procedure the lowest. The analysis of a semen sample, when only the mean of morphometric parameters is used to describe the cell population, is too limited to interpret their fertilizing capacity. It is essential to analyze the complex structure of the samples by defining subpopulations by multivariate methods. With few exceptions, the means of each morphometric parameter differ between the three subpopulations analyzed in each procedure. Only the subpopulations obtained with the MO-NIS procedure showed a significant correlation with male fertility. In short, it is necessary to establish an instrumental standard for the analysis of sperm morphometry to obtain reliable results and we believe that the MO-NIS system presents these basic requirements.     

Natural selection among Kinnaura of the Himalayan highland: A comparative analysis with other Indian and Himalayan populations

The present investigation on fertility and mortality differential among Kinnaura of the Himalayan highland is based on data collected from 160 post-menopausal women belonging to the middle and high altitude region of Kinnaur district of Himachal Pradesh (Indian Himalayas). Selection potential based on differential fertility and mortality was computed for middle-and high-altitude women. Irrespective of the methodology, the total index of selection was found to be highest among middle-altitude women (0.386) as compared with high-altitude (0.370) women, whereas for the total population it is estimated to be 0.384. It was found that the Kinnaura of the Himalayan highland showing moderate index of total selection and relative contribution of the mortality component (Im) to the index of total selection is higher than the corresponding fertility component (If). The analysis of embryonic and post-natal mortality components shows that the post-natal mortality components are higher in comparison with the embryonic mortality components among highlanders and needs special intervention and health care. The present findings are compared with other Indian tribes as well as non-tribes of the Himalayan region and other parts of the country. It reveals that this index among Kinnaura is moderate than the other population groups; among the Himalayan population, the highest was reported for Galong (It = 1.07) of Arunachal, whereas the lowest was reported from Ahom (It = 0.218) of Manipur. The correlation and regression analysis between total index of selection (It) and fertility (If) and mortality (Im) components for pooled data of populations of the Indian Himalayan states show that If and Im account for 21.6 and 29.1% variability, respectively. In Crow's total index of selection (It) along with strong association, which is significant at the 1% level, this indicates that mortality plays a greater role in natural selection in comparison with fertility among populations of the Indian Himalayas.     

The estimation of natural fertility: A micro approach

Abstract

The estimation of natural fertility has heretofore been confined to population aggregates. This paper presents a technique for estimating natural fertility at the household level for developing countries with some practice of deliberate family size limitation and applies it to micro‐level WFS data for Sri Lanka and Colombia for females aged 35–44 in intact marriages. The technique is based on a proximate determinants equation estimated as part of a model that takes account of the interdependence between use of fertility control and natural fertility. To evaluate the results, the mean and household level estimates of natural fertility for each country are first compared with actual fertility; then mean estimates for each country are compared with macro‐level estimates of natural fertility based on three other methods. Finally, the implications of the analysis for the proximate sources of intercountry and intracountry variations in natural fertility are examined. The results suggest that the present approach yields plausible quantitative estimates of natural fertility and reasonable analytical results.     

Tim50a,a nuclear isoform of the mitochondrial Tim50, interacts with proteins involved in snRNP biogenesis

Background  

The Cajal body (CB) is a nuclear suborganelle involved in the biogenesis of small nuclear ribonucleoproteins (snRNPs), which are vital for pre-mRNA splicing. Newly imported Sm-class snRNPs traffic through CBs, where the snRNA component of the snRNP is modified, and then target to other nuclear domains such as speckles and perichromatin fibrils. It is not known how nascent snRNPs localize to the CB and are released from this structure after modification. The marker protein for CBs, coilin, may play a role in snRNP biogenesis given that it can interact with snRNPs and SMN, the protein mutated in Spinal Muscular Atrophy. Loss of coilin function in mice leads to significant viability and fertility problems and altered CB formation.     

A class of goodness of fit tests for a copula based on bivariate right-censored data

The copula of a bivariate distribution, constructed by making marginal transformations of each component, captures all the information in the bivariate distribution about the dependence between two variables. For frailty models for bivariate data the choice of a family of distributions for the random frailty corresponds to the choice of a parametric family for the copula. A class of tests of the hypothesis that the copula is in a given parametric family, with unspecified association parameter, based on bivariate right censored data is proposed. These tests are based on first making marginal Kaplan-Meier transformations of the data and then comparing a non-parametric estimate of the copula to an estimate based on the assumed family of models. A number of options are available for choosing the scale and the distance measure for this comparison. Significance levels of the test are found by a modified bootstrap procedure. The procedure is used to check the appropriateness of a gamma or a positive stable frailty model in a set of survival data on Danish twins.     

Efficient statistical inference procedures for partially nonlinear models and their applications

Summary .   Motivated by an analysis of a real data set in ecology, we consider a class of partially nonlinear models where both a nonparametric component and a parametric component are present. We develop two new estimation procedures to estimate the parameters in the parametric component. Consistency and asymptotic normality of the resulting estimators are established. We further propose an estimation procedure and a generalized F -test procedure for the nonparametric component in the partially nonlinear models. Asymptotic properties of the newly proposed estimation procedure and the test statistic are derived. Finite sample performance of the proposed inference procedures are assessed by Monte Carlo simulation studies. An application in ecology is used to illustrate the proposed methods.     

Commodity aspirations in Easterlin's relative income theory of fertility

This paper presents the preference ordering that underlies Easterlin's relative income theory of fertility. Commodity aspirations are a key component of the theory and the paper explores how the introduction of commodity aspirations into the utility function affects the consumption of commodities and bearing of children. The formation and empirical specification of commodity aspirations are also discussed. Commodity aspirations are formed by the material environment experienced during childhood and are primarily a function of parental income. Easterlin, Leibenstein and Ben-Porath argus that it is the parental consumption or standard of living that determines the child's testes or aspirations. It is the parents' spending on themseleves rather than total parental income that can be used as a proxy for the child's commodity aspirations. Bagozzi and Van Loo identify 4 significant contributions made by Easterlinhs theory of fertility. They cite his stress on potential income flow through time as being pertinent to household decision making; tastes being an explicit determinant of fertility; background charactersticis and norms as to standards of child care and family size affecting fertility indirectly through tastes rather than directly; and the fact that relative income has an effect on fertility in addition to the influence of the absolute level of income. The number of children demanded is a negative function of commodity aspirations, as is the utility of the family. Studies of the demand for commodities and children should include data on parental resources.     

The role of the veterinarian in bovine fertility management on modern dairy farms

The decline in dairy herd fertility internationally has highlighted the limited impact of traditional veterinary approaches to herd fertility. The role of the veterinarian in fertility management on dairy farms has evolved from addressing individual clinical conditions to analyzing suboptimal herd metrics. However, this paradigm shift has only successfully occurred in some dairy industries and less so in others. Needs analyses indicate that the critical constraints to change are veterinary practice size, client motivation and data quality and availability. In addition, this review identified the inability of veterinarians to demonstrate and to market the cost-benefit of their fertility management services as important impediments to change. In many cases change is not being managed but is imposed by the growth of paraprofessionals. Some veterinarians still see their role as an animal clinician while others have evolved into leaders of the herd fertility management team. The core role of dairy veterinarians remains individual animal examinations but this must be supplemented with systematic herd fertility investigation and veterinarian-led herd fertility management. This new role encompasses leading the change from clinical calls only to a planned approach to herd fertility, demonstrating the cost-benefits of the program, scheduling fertility management consultations, assisting the farmer in setting specific, measurable, attainable, relevant and time-limited (SMART) goals, drawing up standard operating procedures (SOPs), training and auditing staff in fertility management practices, encouraging a team approach, implementing veterinary fertility management and monitoring performance. Veterinarians who fail to engage in this process of change risk being marginalized by others keen to promote their herd fertility services.     

Evolution of multiple components of virulence in Drosophila-nematode associations

Abstract.— Virulence is of central importance in host-parasite interactions, yet little is known about how it changes over extended evolutionary periods. In this study, all four species in the testacea species group of Drosophila were experimentally infected with sympatric and allopatric nematodes in the Howardula aoronymphium species complex, and the effect of parasite infection on three components of host fitness was determined. The Drosophila species show striking differences in their responses to infection, with reductions reaching 80% in adult lifespan, 100% in female fertility, and 90% in male fertility. Female sterility appears to be determined by the host; species that are sterilized by their local nematodes are also sterilized by the other allopatric nematodes in the H. aoronymphium complex. Host species that are not sterilized by their local parasite are not sterilized by other nematodes in the complex. In contrast, reductions in host adult lifespan and male fertility depend on both the host and the parasite. Whereas all nematodes reduced the survival of their local host species equally (about 40–45%), survival of two host species was drastically reduced (about 80%) when infected with an allopatric parasite. Thus, virulence is evolutionarily labile in associations between Drosophila testacea group species and their Howardula parasites. The data suggest that changes in the sterility component of virulence are due primarily to host evolution, whereas changes in the host mortality component are due in large part to parasite evolution.     

Nutrition, fertility and maternal investment in primates

While the energetics of reproduction have been intensively investigated among women, studies of mother-offspring relationships among non-human primates have tended to neglect the effect of nutrition of the mother on lactational performance and on growth and survival of offspring. Typically fertility has been compared between populations under different nutritional regimes. In this paper, the relations between suckling frequencies, the time of weaning, the survivorship of offspring, the contraceptive effects of lactation and the quality of maternal diets are outlined. Energy transfer from mother to offspring in the form of milk is proposed as a measurable component of maternal investment, and the behavioural causes and consequences of lactational anoestrus are explored using data from free-ranging vervet monkeys. It is suggested that nutrition of the mother is most important during the early phase of rapid infant growth, because at that time the energetic requirements of lactation are high; and that a mother's ability to assess her infant's demands and needs for nutrition for growth leads to alterations in suckling frequencies which result in variation in female fertility.     

Effect of rearing strategy and gamma radiation on fecundity and fertility of codling moth Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae)

The codling moth Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) is a serious pest of pome fruit worldwide. In an effort to reduce the use of pesticides to control this pest, the sterile insect technique (SIT) is used or considered for use as a component of area‐wide integrated pest management programmes. Rearing codling moths through diapause has been shown to improve the competitiveness of sterile moths released in orchards, and provides management alternatives that would allow mass‐rearing facilities to increase their yearly production of sterile moths. Because radiosensitivity in insects can be influenced by numerous biological factors, laboratory tests were conducted to examine whether the response to increasing doses of radiation, as expressed in the fecundity and fertility of cohorts of moths, is similar for adult moths mass‐reared through diapause or through standard (non‐diapause) production protocols. Our data revealed that the effect of increasing doses of radiation on fecundity and fertility of codling moths reared through both rearing strategies was similar. In the case of fertility, this is a particularly important finding for the expanded application of codling moth SIT. If mass‐rearing facilities use year‐round diapause rearing, the dose required to treat the insects prior to release will be similar to that used when codling moths are reared through standard production protocols.     

Economic and social correlates of infant mortality: A cross‐sectional and longitudinal analysis of 63 selected countries

Abstract

Genealogical records containing birth and death dates for completed families have been analyzed to compare the longevity of twins, sibs and parents. The data are restricted to twins and sibs who survived to adulthood and married. The findings, similar to those found with respect to fertility (Wyshak and White, 1969), show that twins, especially male twins, are disadvantaged in comparison with their male sibs. Sib‐sib and parent‐offspring correlation analysis confirmed that there is a genetic component in the determination of life span, but environmental factors contribute more to the total variation. No evidence of a stronger maternal than paternal effect was found. Twin bearers also lived longer than nontwin bearers. Even among persons who survived to age SO or more, parents of twins had more children and lived slightly longer than their twin and nontwin offspring. Regression analysis for persons who survived to SO or longer indicated that, in addition to life span of parents, secularity (year of death) and fertility (number of children borne) were the best predictors of longevity, though only a small proportion of the variation could be accounted for by these and other demographic variables. Life span has shown a consistent increase over time from the seventeenth century through the nineteenth century, while fertility has tended to decline. However, among persons surviving to age SO, when the relation between secularity and fertility and secularity and longevity is controlled, a significant correlation between fertility and longevity remains. This relation, observed in populations that did not practice voluntary family size limitation, would not be found in contemporary data. Maternal mortality accounted for the shorter life span of women than for men; eliminating its effect gives women a slight advantage. The fertility and longevity experience of migrants who survived to age SO is more favorable than that of persons who did not migrate.     

Sperm yield after single layer centrifugation with Androcoll-E is related to the potential fertility of the original ejaculate

Many attempts have been made to identify laboratory tests that are predictive of sperm fertility, both to improve the quality of stallion semen doses for artificial insemination (AI) and to identify potential breeding sires if no fertility data are available. Sperm quality at the stud is mostly evaluated by assessing subjective motility, although this parameter can be poorly indicative of fertility. Sperm morphology and chromatin integrity in Swedish stallions are correlated to pregnancy rate after AI. Because single layer centrifugation (SLC) selects for spermatozoa with normal morphology and good chromatin, retrospective analysis was carried out to investigate whether sperm yield after SLC is linked to potential fertility. Commercial semen doses for AI from 24 stallions (five stallions with four ejaculates each, 19 stallions with three ejaculates each; n = 77) obtained during the breeding season were cooled, and sent overnight to the Swedish University of Agricultural Sciences in an insulated box for evaluation, with other doses being sent to studs for commercial AI. On arrival at Swedish University of Agricultural Sciences, the semen was used for SLC and also for evaluation of sperm motility, membrane integrity, chromatin integrity, and morphology. The seasonal pregnancy rates for each stallion were available. The yield of progressively motile spermatozoa after SLC (calculated as a proportion of the initial load) was found to be highly correlated with pregnancy rate (r = 0.75; P < 0.001). Chromatin damage was highly negatively correlated with pregnancy rate (r = −0.69; P < 0.001). Pregnancy rate was also correlated with membrane integrity (r = 0.58; P < 0.01), progressive motility (r = 0.63; P < 0.01), and normal morphology (r = 0.45; P < 0.05). In conclusion, these preliminary results show that sperm yield after SLC is related to the potential fertility of the original ejaculate, and could be an alternative indicator of stallion fertility if breeding data are not available. Single layer centrifugation is fast (30 minutes) and does not require expensive equipment, whereas other assays require a flow cytometer and/or specialist skills. An additional option could be to transport semen doses to a laboratory for SLC if the stud personnel do not want to perform the procedure themselves.     

Risk-sensitive fertility: The variance compensation hypothesis

Two conditions are sufficient to indicate the need for risk-sensitive, adaptive analysis: (i) the outcomes of a behavior must be unpredictable to some degree and (ii) the relationship between outcomes and their value (in terms of fitness or utility) must be nonlinear. We argue that these conditions are common, and develop a general model for the analysis of risk-sensitive fertility behavior when long-term reproductive outcomes are unpredictable. We show that unpredictability is likely to have a patterned effect on fertility behavior, beyond adjustment for expected or average mortality, and we analyze the conditions under which that effect will be to promote or dampen fertility (positive or negative variance compensation, respectively). We then describe the implications of this variance compensation hypothesis (VCH) for the analysis of demographic transitions, agricultural intensification, fertility differences in natural-fertility populations, and clutch size. We conclude by lamenting that data are lacking to test the VCH, probably because it has not been appreciated that there can be patterned and effective behavioral adjustments to stochastic features of the environment.     

Resolution of initially excited and relaxed states of tryptophan fluorescence by differential-wavelength deconvolution of time-resolved fluorescence decays

We describe a new procedure for the analysis of time-resolved decays of fluorescence intensity. This procedure was used to resolve the emission spectra of the initially excited and solvent relaxed states of a tryptophan derivative in viscous solution. Specifically, we examined N-acetyl-l-tryptophanamide (AcTrpNH₂) in viscous and nonviscous solutions of propylene glycol. Time-resolved decays of fluorescence intensity were collected at wavelengths across the emission spectra. Instead of the usual procedure of deconvolving these data with the time profile of the exciting pulse, we deconvolved these data using the response observed on the short-wavelength side of the emission. If one assumes that this emission results only from the initially excited state (F), then the nonzero decay time calculated using deconvolution is that of the solvent relaxed state (R). For our specific case of AcTrpNH₂ the emission spectra of the F and R states overlap at most wavelengths longer than the short-wavelength side of the emission (310 nm). As a result, differential-wavelength deconvolution yields two lifetimes and amplitudes, one pair representing the relaxed state and the other the initially excited state. The latter appears as a zero-decay-time component whose amplitude can be readily quantified. The wavelength-dependent amplitude of this zero-lifetime component can be used to calculate the emission spectrum of the F state and. by difference, the emission spectrum of the relaxed state. For AcTrpNH₂ in propylene glycol at ?20°C the emission maxima of the F and R states are near 320 and 350 nm, respectively, and the relative proportion of the emission from each state was near 50%. At lower temperatures the emission from the F state becomes dominant and at high temperatures the emission from the R state dominates. We note that this resolution of states is somewhat arbitrary because we assumed a two-state model and the absence of solvent relaxed emission at 310 nm. Nonetheless, differential-wavelength deconvolution simplifies and facilitates the analysis of time-resolved fluorescence data from samples which undergo excited state reactions. Moreover, this deconvolution procedure considerably simplifies the determination of the kinetic constants for reversible excited state reactions. The application of differential-wavelength deconvolution does not increase the time reqaired for data acquisition. This differential analysis procedure should enhance the usefulness and precision of pulse fluorometric methods in studies of nanosecond time scale processes in proteins and membranes.     

Variability of selection opportunities with changing socio-cultural environments

Opportunity for selection has been studied against their contrasting socioeconomic and cultural backgrounds in two endogamous populations, namely, Brahmins and Jalaris of Visakhapatnam, India. Total selection was slightly higher among the better off Brahmins than in Jalaris. But a marked qualitative and quantitative variation was found in the contributing components; the fertility differential was circa 60% in Brahmins while the mortality differential was circa 60% in Jalaris according to the Crow Index. The decreased mortality differential in Brahmins suggests that this component was directly affected by the better socio-economic level and reflects on the population's transitional phase. Further, the If value fell to a half in women who completed their fertility by family planning when compared to women who completed their fertility by menopause, thus reducing the variance in fertility component in the family planning group.     

Fertility levels and trends in Arsi and Shoa regions of Central Ethiopia

Levels and trends of fertility in the Arsi and Shoa regions of Central Ethiopia are examined, using data from the 1986 Population, Health and Nutrition baseline survey of the Ministry of Health of Ethiopia. The population has high fertility. Total fertility of six children per woman in the late 1960s increased to eight children per woman in the early 1980s, then declined to seven children per woman in the mid-1980s. Urban fertility declined by a substantial amount during the 15 years before the survey while rural fertility increased during the same period. The implications of high fertility are considered.