215 research outputs found

    ETP-0474: Evaluation of Electroless Nickel Coatings to Achieve Interference Fit in the RSRM Without Fretting

    Get PDF
    Part of the redesign of the SRMs for the Space Shuttle involved the substitution of three new capture cylinders for three of the previously used cylinders. These new cylinders mate with the old standard case segments in each of the three field joints. The new capture cylinders contain an integral capture latch on the tang end which mates with a case clevis during stackup at KSC. The capture cylinders also contain a groove in the capture latch to provide for a third 0-ring in the joint and are designed to achieve a metal-to- metal interference fit between the capture latch and the mating clevis. An unexpected fretting problem has occurred on the tang capture feature and the inner clevis leg interference fit surfaces on flight hardware since STS-26. Varying degrees of fretting damage have been found on the case segments from different flight motors. Fretting is a wear phenomena that occurs when two tightly fitting metal surfaces are subject to cyclic relative motion of extremely small amplitudes (generally less than 0.010-inch) in the absence of adequate lubrication. It is adhesive ("cold" - welding) in nature and vibration is its essential causative factor. This problem has manifested itself on the flight motors as a series of pits and axial gouges on the inside diameter (ID) surfaces of the inner clevis legs and the outside diameter (OD) surfaces of the tang capture features. The problem occurs in varying degrees of severity in all of the field joints. It is not believed that fretting is a flight safety issue. However, it could become a reusability issue if left unattended. Fretting has been encountered in other industries for many years and measures that will prevent or reduce it have been devised. These include: elimination or reduction of vibration (amplitudes and/or frequencies), elimination of slip, improved lubrication between parts, increased surface separation, increased interference, inducing residual compressive stresses in the surfaces of the mating parts, and employing non-fretting interference shims. Looking at each of these separately; vibration and slip occur in varying degrees and magnitudes in the field joints (as part of the roll-out, launch, flight, splashdown, flotation, and/or tow back) and are difficult to define or eliminate. Improved lubrication is something that was evaluated since it would be the simplest change to incorporate, but little or no improvement was found. Increasing surface separation would defeat the purpose of the interference fit. The effect of increasing the interference fit is unknown. Additional shot peening and/or surface rolling to impart residual compressive stresses in the joints undoubtedly would alter the characteristics and finish of the sealing surfaces of the motor cases. Also, experimental data' indicate that the tangs and clevises already have residual compressive stress fields on their surfaces yet fretting occurs. These stresses probably result from the case machining and the glass beading used to clean these surfaces

    Intergenerational support and women’s fertility in high-income countries: an evolutionary analysis

    Get PDF
    There is now considerable evidence that humans are cooperative breeders – that is, women need allomaternal support to successfully reproduce. Families play a key role in providing this support to women. Evidence from low-income contexts linking allomaternal support to beneficial child outcomes is particularly strong, but associations between support and successful reproduction are more varied in high-income settings and when fertility is the outcome. Two possible reasons for this are (1) allocare is measured in many forms and at many time points with potentially different meanings for reproductive women, and (2) highincome populations are very heterogeneous, including large socioeconomic inequalities, which may modify associations between support and fertility. This publication-based dissertation has three main objectives: (1) to contribute to cooperative breeding literature in high-income, low-fertility settings; (2) to deepen our understanding of how family support plays into reproductive decision making by testing associations between many types of support and women’s fertility; and (3) to explore contextual factors, particularly socioeconomic position, with may moderate associations between family support and women’s fertility. These objectives are investigated in four research chapters (two published and two written for submission) using secondary data from low-fertility, high-income countries. This research firstly confirms that families provide key allomaternal support for women in high-income countries, while also highlighting other sources of support. However, the results demonstrate that all support is not equal. Types, timing, and sources of support vary in terms of their influence on reproductive outcomes (e.g.in the United Kingdom, material or practical support often associates with lower fertility while non-material support associates with higher fertility). Secondly, this research demonstrates that socioeconomic environments modify many components of the reproductive decision making process, not the least of which is how families interact with and support each other and, in turn, how family support associates with fertility outcomes

    Support for new mothers and fertility in the United Kingdom: Not all support is equal in the decision to have a second child.

    Get PDF
    Low fertility across Europe highlights the need to understand reproductive decisions in high-income countries better. Availability of support may be one factor influencing reproductive decisions, though within high-income countries availability varies between environments, including socio-economic environments. We test whether receiving higher levels of support, from different sources (informal and formal) and of different types (practical and emotional), is positively correlated with second births in the United Kingdom (UK) Millennium Cohort Study, and whether these relationships differ by socio-economic position (SEP). Our hypothesis is only partially supported: receiving emotional support correlates with higher likelihood of second birth, but the opposite is true for practical support. Availability of different types of support varies across SEP, but relationships between support and fertility are similar, with one exception: kin-provided childcare increases the likelihood of birth only among lower-SEP women. Our results highlight that not all support is equal in the decision to have a second child

    It's not just about the future: The present payoffs to behaviour vary in degree and kind between the rich and the poor.

    Get PDF
    Pepper & Nettle offer a nuanced and humane view on poverty that should be required reading for policy makers, particularly those interested in "behaviour change" policy. We suggest, however, that the emphasis on "future-discounting" in this paper downplays the importance of differences in the payoffs to behaviours in the present and how these payoffs may be realised in different currencies

    ΠŸΡ€ΠΎΠ±Π»Π΅ΠΌΡ‹ измСрСния экономичСского благополучия Ρ‡Π΅Π»ΠΎΠ²Π΅ΠΊΠ° Π² условиях экологизации экономики ΠΈ ΠΏΡ€ΠΎΠΌΡ‹ΡˆΠ»Π΅Π½Π½Ρ‹Ρ… прСдприятий

    Get PDF
    ΠŸΡ€ΠΎΠ²Π΅Π΄Π΅Π½ Π°Π½Π°Π»ΠΈΠ· качСства ΠΆΠΈΠ·Π½ΠΈ ΠΈ уровня экономичСского благополучия Π³Ρ€Π°ΠΆΠ΄Π°Π½ Π² соврСмСнном ΠΌΠΈΡ€Π΅. Π‘ΠΎΠ±Ρ€Π°Π½Ρ‹ статистичСскиС Π΄Π°Π½Π½Ρ‹Π΅, Π½Π° основС ΠΊΠΎΡ‚ΠΎΡ€Ρ‹Ρ… сдСланы Π²Ρ‹Π²ΠΎΠ΄Ρ‹ ΠΎ цСлСсообразности ΠΎΡ†Π΅Π½ΠΊΠΈ благополучия Ρ‡Π΅Π»ΠΎΠ²Π΅ΠΊΠ° Π² ΡΠ»ΠΎΠΆΠΈΠ²ΡˆΠΈΡ…ΡΡ производствСнно-тСхничСских условиях. ΠŸΡ€ΠΎΠ²Π΅Π΄Π΅Π½ΠΎ сравнСниС ΠΌΠ΅Ρ‚ΠΎΠ΄ΠΎΠ² ΠΎΡ†Π΅Π½ΠΊΠΈ благополучия Π³Ρ€Π°ΠΆΠ΄Π°Π½ Π½Π° основС Ρ€Π°Π·Π»ΠΈΡ‡Π½Ρ‹Ρ… ΠΏΠΎΠΊΠ°Π·Π°Ρ‚Π΅Π»Π΅ΠΉ ΠΈ ΠΊΡ€ΠΈΡ‚Π΅Ρ€ΠΈΠ΅Π². ΠŸΡ€ΠΎΠ²Π΅Π΄Π΅Π½Π° ΠΎΡ†Π΅Π½ΠΊΠ° качСства ΠΆΠΈΠ·Π½ΠΈ Π³Ρ€Π°ΠΆΠ΄Π°Π½ России. ΠžΡΡƒΡ‰Π΅ΡΡ‚Π²Π»Π΅Π½ΠΎ сравнСниС благосостояния Π³Ρ€Π°ΠΆΠ΄Π°Π½ с ΡƒΡ‡Π΅Ρ‚ΠΎΠΌ Π³Π΅Π½Π΄Π΅Ρ€Π½ΠΎΠΉ принадлСТности, экономичСского ΠΈ ΡΠΎΡ†ΠΈΠ°Π»ΡŒΠ½ΠΎ-политичСского развития стран. ΠžΠΏΡ€Π΅Π΄Π΅Π»Π΅Π½Ρ‹ ΠΏΡ€ΠΎΠ±Π»Π΅ΠΌΡ‹ измСрСния экономичСского благополучия Ρ‡Π΅Π»ΠΎΠ²Π΅ΠΊΠ°

    Shared interests or sexual conflict? Spousal age gap, women's wellbeing and fertility in rural Tanzania

    Get PDF
    The marriage of older men to younger women is common across cultures. On one hand, husband-older marriage may serve the interests of both sexes, a conclusion broadly consistent with reported gender differences in mate preferences. On the other hand, men alone may benefit from such marriages at a cost to women if seniority enables men to exert dominance in conflicts of interest. Indeed, in public health large spousal age gaps are generally deemed β€œpathological”, both as a cause and consequence of gender inequalities harmful to women. We investigate these alternative models of spousal age gap using data from a cross-sectional survey of women in Mwanza, northwestern Tanzania (n = 993). Consistent with the notion that spousal age gaps are a product of sexual conflict, women typically married with a larger age gap than stated ideals. However, adjusting for potential confounds, spousal age gap was not associated with fertility or the risk of divorce. Furthermore, women's mental health and autonomy in household decision-making was higher in husband-older marriages compared to rare cases of same-age or wife-older marriage. Beyond this comparison, the magnitude of spousal age gaps was unrelated to either measure of women's wellbeing among the overwhelming majority of marriages where the husband was older. Together these findings suggest husband-older marriage does not influence marital stability, relatively large spousal age gaps are neither especially costly nor beneficial to women, and that alternative sociodemographic factors are more important in driving variation in women's wellbeing and reproductive success in this context. Our results support neither a model of mutual benefits, nor a pathological conceptualization of spousal age gaps. We conclude by both encouraging evolutionary human scientists to engage more fully with models of sexual conflict in future studies of marriage and mating, and suggesting that public health scholars consider more neutral interpretations of spousal age differences

    Evaluating the impact of the DREAMS partnership to reduce HIV incidence among adolescent girls and young women in four settings: a study protocol.

    Get PDF
    BACKGROUND: HIV risk remains unacceptably high among adolescent girls and young women (AGYW) in southern and eastern Africa, reflecting structural and social inequities that drive new infections. In 2015, PEPFAR (the United States President's Emergency Plan for AIDS Relief) with private-sector partners launched the DREAMS Partnership, an ambitious package of interventions in 10 sub-Saharan African countries. DREAMS aims to reduce HIV incidence by 40% among AGYW over two years by addressing multiple causes of AGYW vulnerability. This protocol outlines an impact evaluation of DREAMS in four settings. METHODS: To achieve an impact evaluation that is credible and timely, we describe a mix of methods that build on longitudinal data available in existing surveillance sites prior to DREAMS roll-out. In three long-running surveillance sites (in rural and urban Kenya and rural South Africa), the evaluation will measure: (1) population-level changes over time in HIV incidence and socio-economic, behavioural and health outcomes among AGYW and young men (before, during, after DREAMS); and (2) causal pathways linking uptake of DREAMS interventions to 'mediators' of change such as empowerment, through to behavioural and health outcomes, using nestedΒ cohort studies with samples of ~ 1000-1500 AGYW selected randomly from the general population and followed for two years. In Zimbabwe, where DREAMS includes an offer of pre-exposure HIV prophylaxis (PrEP), cohorts of young women who sell sex will be followed for two years to measure the impact of 'DREAMS+PrEP' on HIV incidence among young women at highest risk of HIV. In all four settings, process evaluation and qualitative studies will monitor the delivery and context of DREAMS implementation. The primary evaluation outcome is HIV incidence, and secondary outcomes include indicators of sexual behavior change, and social and biological protection. DISCUSSION: DREAMS is, to date, the most ambitious effort to scale-up combinations or 'packages' of multi-sectoral interventions for HIV prevention. Evidence of its effectiveness in reducing HIV incidence among AGYW, and demonstrating which aspects of the lives of AGYW were changed, will offer valuable lessons for replication

    Religiosity is associated with greater size, kin density, and geographic dispersal of women's social networks in Bangladesh

    Get PDF
    Human social relationships, often grounded in kinship, are being fundamentally altered by globalization as integration into geographically distant markets disrupts traditional kin based social networks. Religion plays a significant role in regulating social networks and may both stabilize extant networks as well as create new ones in ways that are under-recognized during the process of market integration. Here we use a detailed survey assessing the social networks of women in rural Bangladesh to examine whether religiosity preserves bonds among kin or broadens social networks to include fellow practitioners, thereby replacing genetic kin with unrelated co-religionists. Results show that the social networks of more religious women are larger and contain more kin but not more non-kin. More religious women's networks are also more geographically diffuse and differ from those of less religious women by providing more emotional support, but not helping more with childcare or offering more financial assistance. Overall, these results suggest that in some areas experiencing rapid social, economic, and demographic change, religion, in certain contexts, may not serve to broaden social networks to include non-kin, but may rather help to strengthen ties between relatives and promote family cohesion

    The impact of market integration on arranged marriages in Matlab, Bangladesh

    Get PDF
    Success in marriage markets has lasting impacts on women's wellbeing. By arranging marriages, parents exert financial and social powers to influence spouse characteristics and ensure optimal marriages. While arranging marriages is a major focus of parental investment, marriage decisions are also a source of conflict between parents and daughters in which parents often have more power. The process of market integration may alter parental investment strategies, however, increasing children's bargaining power and reducing parents’ influence over children's marriage decisions. We use data from a market integrating region of Bangladesh to (1) describe temporal changes in marriage types, (2) identify which women enter arranged marriages, and (3) determine how market integration affects patterns of arranged marriage. Most women's marriages were arranged, with love marriages more recent. We found few predictors of who entered arranged versus love marriages, and family-level market integration did not predict marriage type at the individual-level. However, based on descriptive findings, and findings relating women's and father's education to groom characteristics, we argue that at the society-level market integration has opened a novel path in which daughters use their own status, gained via parental investments, to facilitate good marriages under conditions of reduced parental assistance or control
    • …
    corecore