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PubMed2001

Mothers and others: who invests in children's health?

We estimate the impact of family structure on investments made in children's health, using data from the 1988 National Health Interview Survey Child Health Supplement. Controlling for household size, income and characteristics, we find that children living with step-mothers are significantly less likely to have routine doctor and dentist visits, or to have a place for usual medical care, or for sick care. Who invests in children's health? It appears these investments are made, largely, by a child's mother, and that step-mothers are not substitutes for birth-mothers in this domain.

Adolescent↗

PubMed1999

Successful sons or advantaged daughters? The Trivers-Willard model and sex-biased maternal investment in ungulates.

The Trivers-Willard model predicts that in polygynous species, given certain assumptions, mothers with extra resources should bias investment towards sons by adjusting sex ratio at birth and/or by differential provisioning of sons and daughters. Evidence for facultative adjustment of the birth sex ratio from recent empirical studies on ungulates is equivocal at best. However, studies on maternal input and reproductive costs suggest that ungulate mothers do discriminate against daughters during maternal investment in the most polygynous, dimorphic species. Better data on the relationship between maternal input and fitness returns for producing sons or daughters are needed to interpret patterns of sex-biased maternal investment.

Journal Article↗

PubMed1998

Egg components and hatchling lipid reserves: parental investment in kinosternid turtles from the southeastern United States.

We measured egg components and pre-ovulatory parental investment in kinosternid turtles (Kinosternon baurii, Kinosternon subrubrum, Sternotherus minor, and Sternotherus odoratus) from the southeastern USA. Allocation patterns were determined by comparing lipid content of eggs and hatchlings, to determine whether females of species with hatchlings that exhibit a delayed nest-emergence strategy: (1) allocate higher proportions of energy storage lipids to eggs, (2) produce hatchlings with higher levels of storage lipids, and (3) have higher levels of pre-ovulatory parental investment in comparison to species whose hatchlings exhibit immediate emergence. Whereas total non-polar lipid (NPL) proportions by dry mass of eggs varied significantly among species, NPL proportions of hatchlings were not significantly different. Pre-ovulatory parental investment in care (proportion of hatchling NPL to egg NPL) was 40, 50, and 55% for K. subrubrum, S. minor, and S. odoratus, respectively. Lipid class composition of eggs and hatchlings was studied to distinguish lipids allocated for energy storage from those allocated to other functions. For both eggs and hatchlings, individual lipid classes (triacylglycerol, triacylglycerol fatty acid, cholesterol, cholesterol ester, and phospholipid) as proportions of total lipid, were similar among species. The major lipid class component of eggs and hatchlings of all species was triacylglycerol (> 83%), an energy storage lipid. Substantial changes in lipid classes during embryogenesis were similar among species and included: (1) depletion of triacylglycerol, (2) increase in cholesterol esters, and (3) changes in phospholipid composition. Incubation time varied significantly among species, and appeared to be responsible for differential energy utilization during embryogenesis. Our results are inconsistent with the previously observed pattern that hatchlings exhibiting a delayed nest-emergence strategy are allocated higher proportions of energy storage lipids than those that exhibit immediate emergence. However, because the species that overwinters in the nest (K. subrubrum) hatches approximately 40 days later than the species that typically does not (S. odoratus), hatchling K. subrubrum may contain higher non-polar lipid proportions than hatchling S. odoratus during similar winter time periods. Kinosternid hatchlings contain enough stored lipids to support basal maintenance costs for substantial time periods. We suggest that such reserves may be critical to hatchling survival during a period of negative energy balance, regardless of nest emergence strategy.

Animals↗

PubMed2000

Paternal investment and the human mating system.

Paternal investment has long been considered responsible for the evolution of predominantly monogamous marriage in humans. However, male-male competition resulting in mate-guarding and male coercion could be equally important. In this review, I use a comparative approach to examine the effect of variation in human paternal investment on our mating system. I conclude paternal investment is important but so too is mate-guarding. I propose a model of our mating system incorporating both factors. Variation in the mating system is explained by variation in male resource control and contribution, resulting in ecologically imposed monogamy or polygyny, as predicted by the polygyny threshold model, as well as variation in male-male competition for status, resulting in socially imposed monogamy or polygyny.

Journal Article↗

PubMed2000

Mechanical properties of dental investment materials.

Measurement of the elastic modulus (E) of investment materials has been difficult because of their low strength. However, these values are essential for engineering simulation and there are many methods available to assess the elasticity of materials. The present study compared two different methods with one of the methods being non-destructive in nature and can be used for specimens prepared for other tests. Two different types of investment materials were selected, gypsum-and phosphate-bonded. Method 1 is a traditional three-point bending test. Twelve rectangular bars with dimension of (70 x 9 x 3 mm) were prepared and placed on supports 56.8 mm apart. The test was conducted at a cross-head speed of 1 mm/min by use of a universal testing machine. The load applied to the test specimen and the corresponding deflection were measured until the specimen fractured. The E value was calculated from a linear part of the stress-strain plot. Method 2 is an ultra micro-indentation system to determine near surface properties of materials with nanometer resolution. The measurement procedure was programmed such that the specimens were indented with an initial contact force of 5 mN then followed by a maximum force of 500 mN. Measurement consisted of 10 indentations conducted with a spherical stainless steel indenter (R = 250 microm) that were equally spaced (500 microm). The E value rose asymptotically with depth of penetration and would approach the three-point bending test value at approximately four time's maximum contact depth for both materials. Both methods are practical ways of measuring the E of investment materials.

Journal Article↗

PubMed2003

Familias Unidas: the efficacy of an intervention to promote parental investment in Hispanic immigrant families.

This paper reports a test of the efficacy of Familias Unidas, a Hispanic-specific, ecologically focused, parent-centered preventive intervention, in promoting protection against and reducing risk for adolescent behavior problems. Specifically, the intervention was designed to foster parental investment, reduce adolescent behavior problems, and promote adolescent school bonding/academic achievement, all protective factors against drug abuse and delinquency. One-hundred sixty seven Hispanic families of 6th and 7th grade students from three South Florida public schools were stratified by grade within school and randomly assigned to intervention and no-intervention control conditions. Results indicated that Familias Unidas was efficacious in increasing parental investment and decreasing adolescent behavior problems, but that it did not significantly impact adolescent school bonding/academic achievement. Summer-vacation rates of adolescent behavior problems were six times higher in the control condition than in the intervention condition. Furthermore, change in parental investment during the intervention was predictive of subsequent levels of adolescent behavior problems. The findings suggest that Familias Unidas is efficacious in promoting protection and reducing risk for adolescent problem behaviors in poor immigrant Hispanic families.

Adolescent↗

PubMed1995

Matching treatment focus to patient social investment and support: 18-month follow-up results.

Patients were randomly assigned to 1 of 3 treatments: brief broad-spectrum (BBS), extended relationship enhancement (ERE), or extended cognitive-behavioral (ECB). A hierarchical latent growth model was used to analyze the data of 188 patients (82%) followed for 18 months. ERE treatment was significantly more effective in increasing abstinence of patients entering treatment with a network unsupportive of abstinence or with a low level of investment in their network, whereas BBS treatment was more effective for patients with either (a) both a social network unsupportive of abstinence and a low level of network investment or (b) high investment in a network supportive of abstinence. ECB outcomes were neither as good as those matched nor as bad as those mismatched to the different exposures of relationship enhancement. This suggests that dose of relationship enhancement should be determined after assessing patient relationships.

Adult↗

PubMed2004

Maternal investment affects offspring phenotypic plasticity in a viviparous cockroach.

Maternal effects, crossgenerational influences of the mother's phenotype on phenotypic variation in offspring, can profoundly influence the fitness of offspring. In insects especially, social interactions during larval development also can alter life-history traits. To date, however, no experimental design, to our knowledge, has manipulated the prenatal and postnatal environments independently to investigate their interaction. We report here that the degree of maternal nutrient investment in developing embryos of the viviparous cockroach Diploptera punctata influences how quickly neonate males become adults and how large they are at adulthood. An offspring's probability of reaching adulthood in fewer than four molts increased with birth weight: the heavier neonates were, consequently, more likely to become smaller adults. Social interaction also affected nymphal development and adult size. Nymphs reared in pairs molted fewer times than solitary nymphs and, thus, became smaller adults. The social effect on developmental trajectory was, however, eliminated by experimentally increasing the level of maternal nutrient investment per offspring, which was accomplished by removing one of the female's paired ovaries (allometric engineering). We conclude that a particular prenatal environment can result in different offspring phenotypes under different postnatal social conditions. By investing more in each offspring, however, D. punctata mothers, because they are viviparous, are able to produce broods with environmentally (socially) independent phenotypes.

Animals↗

PubMed1977

Parental investment, mate choice, and mate quality.

Current theory in sexual selection is extended to predict within-sex variability with regard to selectivity towards mates in different mating systems. Generally, the sex that invests more in the care of each offspring should be more selective of mates than the sex investing less. Within each sex, individuals of low male quality should be less selective than individuals of high quality, but there should be less variation in selectivity among individuals of the sex investing more. When only one sex contributes parental care, however, individuals of that sex should be uniformly selective, while the other sex is expected to mate indiscriminately. Using feral pigeons (Columba livia), these hypotheses are tested for the case in which both sexes contribute substantial parental care, but in which females contribute more than males. As predicted, females were found to be more selective of mates than males were. On certain criteria, males of lower quality were less selective of mates than males of higher quality.

Animals↗

PubMed1995

Paternal investment affects prevalence of malaria.

Both reproduction and parasite defense can be costly, and an animal may face a trade-off between investing in offspring or in parasite defense. In contrast to the findings from nonexperimental studies that the poorly reproducing individuals are often the ones with high parasite loads, this life-history view predicts that individuals with high reproductive investment will show high parasite prevalence. Here we provide an experimental confirmation of a positive association between parental investment levels of male great tits Parus major and the prevalence of Plasmodium spp, a hematozoa causing malaria in various bird species. We manipulated brood size, measured feeding effort of both males and females, and assessed the prevalence of the hemoparasite from blood smears. In enlarged broods the males, but not the females, showed significantly higher rates of food provisioning to the chicks, and the rate of malarial infection was found to be more than double in male, but not female, parents of enlarged broods. The findings show that there may be a trade-off between reproductive effort and parasite defense of the host and also suggest a mechanism for the well documented trade-off between current reproductive effort and parental survival.

Animals↗

PubMed1988

Personal investment predictors of life satisfaction among physically active middle-aged and older adults.

The purpose of this study was to determine the relationship between the social psychological components of personal investment and life satisfaction among 85 middle-aged and older men and women participating in a structured exercise program. Specifically, we examined the degree to which personal incentives for exercise, perceptions of a sense of self, and the congruency between the exercise program and the participants' goals, predicted life satisfaction. Multiple regression analyses revealed that the social psychological variables reflecting personal investment accounted for 52% of the variance for life satisfaction in physically active middle-aged and older adults. The personal investment theory is supported as a framework for investigating psycho-social predictors of situational outcomes such as life satisfaction.

Aged↗

PubMed1994

Economic analysis of investment priorities for measles control.

An investment strategy in measles control should strike an appropriate balance among three areas: implementation of existing vaccination programs with existing technology, operations research to improve the use of existing technology, and vaccine development. As a benchmark, the existing Schwarz vaccine costs approximately $17 per DALY (disability-adjusted life year), already making it one of the most cost-effective health interventions in developing countries. National measles vaccination campaigns, such as Brazil's, are a promising extension of this technology. Operations research is indicated to study the organization of campaigns, supplying and delivering vitamin A to hospitalized children, and other issues. The development and application of an early one-dose measles vaccine would be particularly cost-effective ($5 per DALY), as it could avoid the costs to families and health institutions of the separate visit at 9 months now required for measles vaccination. All three areas present opportunities for cost-effective investments and deserve a place in an investment strategy.

Child, Preschool↗

PubMed1999

Biomass investment in leaf lamina versus lamina support in relation to growth irradiance and leaf size in temperate deciduous trees.

Foliar biomass investment in support and assimilative compartments was studied in four temperate deciduous tree species along a natural light gradient across the canopy. The species ranked according to shade tolerance as Betula pendula Roth. < Populus tremula L. < Fraxinus excelsior L. < Tilia cordata Mill. Long-term light conditions at sampling locations were characterized as seasonal mean integrated quantum flux density (Q(int), mol m(-2) day(-1)) estimated by a method combining hemispherical photography and light measurements with quantum sensors. Leaf morphology was altered by Q(int) in all species. Both lamina and petiole dry mass per lamina area (LMA and PMA, respectively) increased with increasing Q(int). Shade-tolerant species had lower LMA at low Q(int) than shade-intolerant species; however, PMA was not related to shade tolerance. Across species, the ratio of petiole dry mass to lamina dry mass (PMR) varied from 0.07 to 0.21. It was independent of Q(int) in the simple-leaved species, but decreased with increasing Q(int) in the compound-leaved F. excelsior, which also had the largest foliar biomass investment in petioles. Differences in leaf mass and area, ranging over four orders of magnitude, provided an explanation for the interspecific variability in PMR. Species with large leaves also had greater biomass investments in foliar support than species with smaller leaves. This relationship was similar for both simple- and compound-leaved species. There was a negative relationship between PMR and petiole N concentration, suggesting that petioles had greater carbon assimilation rates and paid back a larger fraction of their construction cost in species with low PMR than in species with high PMR. This was probably the result of a negative relationship between PMR and petiole surface to volume ratio. Nevertheless, petioles had lower concentrations of mineral nutrients than laminas. Across species, the ratio of petiole N to lamina N varied from only 3 to 6%, demonstrating that petiole costs are less in terms of nutrients than in terms of total biomass, and that the petiole contribution to carbon assimilation is disproportionately lower than that of the lamina contribution.

Journal Article↗

PubMed2002

Pharmacologic treatments for dry eye: a worthwhile investment?

PURPOSE: To determine whether investment in a novel pharmacologic agent for the treatment of dry eye would be worthwhile from a financial perspective. METHODS: Estimates were made of the cost and time required to develop a novel pharmacologic treatment of dry eye and the potential revenues for the product. These estimates were used to compute the value of the investment, adjusting for the time value of money. RESULTS: Development was estimated to cost $42 million and to take 55 months from investigational new drug exemption filing to new drug application approval. The potential market for this treatment was estimated at $542 million per year at year 5. Adding in the cost of development and marketing as well as other costs, net present value was very positive at the 5, 8, 10, and 40% cost of financing. The internal rate of return was 90%. CONCLUSION: In summary, if there were a successful pharmacologic treatment of dry eye and if a firm could manage the cash flow during the development, then the market potential approaches that of other treatment of chronic ophthalmic conditions (e.g., glaucoma), and it would be a worthwhile investment.

Chemistry, Pharmaceutical↗

PubMed1999

Abortion rates reflect the optimization of parental investment strategies.

Parental investment decisions in human beings, including infanticide, have usually been considered in relation to the postnatal survival probabilities of their children. A number of factors which influence parental ability and willingness to invest in offspring have been identified from these studies. Here we argue that at least some of the same factors which influence investment decisions postpartum also affect the decision to terminate a current pregnancy through voluntary abortion. We show that both female age and marital status influence the probability of abortion, with the key variable being the likelihood of future marriage. Thus, abortion procedures extend a woman's ability to manage her reproduction into the prenatal period.

Abortion, Induced↗

PubMed2001

Trends in the maternal investment of harbour porpoises are uncoupled from the dynamics of their primary prey.

Harbour porpoises in the Bay of Fundy and Gulf of Maine feed primarily on Atlantic herring. Herring stocks have undergone dramatic fluctuations in abundance over the past three decades due to changes in fishing intensity. In order to understand the effects of these changes in prey abundance on the patterns of maternal investment, I examined interdecadal variation in the size of porpoise calves measured in August prior to weaning. Female harbour porpoises exhibited significant variation in maternal investment between 1970 and 1999. During the 1980s, females consumed more herring and produced larger calves. Surprisingly, however, this increased maternal investment occurred during the period of lowest prey abundance, perhaps because the herring stock assessment does not reflect the availability or quality of prey to female porpoises.

Adipose Tissue↗

PubMed2004

Immunological investments reflect parasite abundance in island populations of Darwin's finches.

The evolution of parasite resistance can be influenced by the abundance of parasites in the environment. However, it is yet unresolved whether vertebrates change their investment in immune function in response to variation in parasite abundance. Here, we compare parasite abundance in four populations of small ground finches (Geospiza fuliginosa) in the Galapagos archipelago. We predicted that populations exposed to high parasite loads should invest more in immune defence, or alternatively use a different immunological defence strategy. We found that parasite prevalence and/or infection intensity increased with island size. As predicted, birds on large islands had increased concentrations of natural antibodies and mounted a strong specific antibody response faster than birds on smaller islands. By contrast, the magnitude of cell-mediated immune responses decreased with increasing parasite pressure, i.e. on larger islands. The data support the hypothesis that investments into the immune defence are influenced by parasite-mediated selection. Our results are consistent with the hypothesis that different immunological defence strategies are optimal in parasite-rich and parasite-poor environments.

Analysis of Variance↗

PubMedDate not supplied

How money matters for young children's development: parental investment and family processes.

This study used data from the Panel Study of Income Dynamics and its 1997 Child Development Supplement to examine how family income matters for young children's development. The sample included 753 children who were between ages 3 and 5 years in 1997. Two sets of mediating factors were examined that reflect two dominating views in the literature: (1) the investment perspective, and (2) the family process perspective. The study examined how two measures of income (stability and level) were associated with preschool children's developmental outcomes (Woodcock-Johnson [W-J] Achievement Test scores and the Behavior Problem Index [BPI]) through investment and family process pathways. Results supported the hypothesis that distinct mediating mechanisms operate on the association between income and different child outcomes. Much of the association between income and children's W-J scores was mediated by the family's ability to invest in providing a stimulating learning environment. In contrast, family income was associated with children's BPI scores primarily through maternal emotional distress and parenting practices. Level of income was associated with W-J letter-word scores and income stability was associated with W-J applied problem scores and BPI, even after all controls were included in the models.

Attitude↗