A survey of structural material issues for a space station

An NASA enters the definition phase of the space station project, one of the important issues to be considered is structural material selection. The complexity of the space station and its long life requirement are two key factors which must be considered in the material selection process. Both aluminum and graphite/epoxy are considered as potential structural materials. Advantages and disadvantages of these materials with respect to mechanical and thermal considerations, space environment, manufacturing, and cost are discussed

The structural behavior of a graphite-polymide honeycomb sandwich panel with quasi-isotropic face sheets and an orthotropic core

The results of a series of tests of graphite-polyimide honeycomb sandwich panels are presented. The panels were 1.22 m long, 0.508 m wide, and approximately 13.3 m thick. The face sheets were a T-300/PMR-15 fabric in a quasi-isotropic layup and were 0.279 mm thick. The core was Hexcel HRH 327-3/16 - 4.0 glass reinforced polyimide honeycomb, 12.7 mm thick. Three panels were used in the test: one was cut into smaller pieces for testing as beam, compression, and shear specimens; a second panel was used for plate bending tests; the third panel was used for in-plane stability tests. Presented are the experimental results of four point bending tests, short block compression tests, core transverse shear modulus, three point bending tests, vibration tests, plate bending tests, and panel stability tests. The results of the first three tests are used to predict the results of some of the other tests. The predictions and experimental results are compared, and the agreement is quite good

Thermal cycling graphite-polyimide

The effects of repetitive thermal cycling on the temperature-thermal deformation relation of graphite-polyimide were determined. The bending and axial strains, measured with strain gages, of unsymmetric 0 deg sub 2/90 deg sub 2 and 0 deg sub 4/90 deg sub 4 laminates were used as an indication of thermal deformation. The strains were measured as a function of temperature and two temperature ranges were used, room temperature to 180 C and room temperature to 315 C. Five cycles were run in each temperature range and the cycling was done in quasistatic fashion. The response of a flat 0 deg sub 8 laminate was measured as were the effects of repetitive cycling on the strain gages themselves. A piece-wise linear theory, based on classical lamination theory and using the variation of mechanical and thermal expansion properties with temperature, was compared with the experimental results. The correlation between theoretical predictions and experimental results for the thinner laminate was poor

Buckling and failure characteristics of graphite-polyimide shear panels

The buckling and failure characteristics of unstiffened, blade stiffened, and hat stiffened graphite-polyimide shear panels are described. The picture frame shear test is used to obtain shear stress-strain data at room temperature and at 316 deg C. The experimental results are compared with a linear buckling analysis, and the specimen failure modes are described. The effect of the 316 deg C test temperature on panel behavior are discussed

Why Do You Always Cry

https://digitalcommons.library.umaine.edu/mmb-vp/5372/thumbnail.jp

Prescription Drug Abuse Communication: A Qualitative Analysis of Prescriber and Pharmacist Perceptions and Behaviors

Background: Interpersonal communication is inherent in a majority of strategies seeking to engage prescriber and pharmacist health care professionals (HCPs) in the reduction and prevention of prescription drug abuse (PDA). However, research on HCP PDA communication behavioral engagement and factors that influence it is limited. Objectives This study quantitatively examined communication behaviors and trait-level communication metrics, and qualitatively described prescription drug abuse-related communication perceptions and behaviors among primary care prescribers and community pharmacists. Methods: Five focus groups (N = 35) were conducted within the Appalachian Research Network (AppNET), a rural primary care practice-based research network (PBRN) in South Central Appalachia between February and October, 2014. Focus groups were structured around the administration of three previously validated trait-level communication survey instruments, and one instrument developed by the investigators to gauge HCP prescription drug abuse communication engagement and perceived communication importance. Using a grounded theory approach, focus group themes were inductively derived and coded independently by study investigators. Member-checking interviews were conducted to validate derived themes. Results: Respondents\u27 trait-level communication self-perceptions indicated low communication apprehension, high self-perceived communication competence, and average willingness to communicate as compared to instrument specific criteria and norms. Significant variation in HCP communication behavior engagement was noted specific to PDA. Two overarching themes were noted for HCP-patient communication: 1) influencers of HCP communication and prescribing/dispensing behaviors, and 2) communication behaviors. Multiple sub-themes were identified within each theme. Similarities were noted in perceptions and behaviors across both prescribers and pharmacists. Conclusions: Despite the perceived importance of engaging in PDA communication, HCPs reported that prescription drug abuse communication is uncomfortable, variable, multifactorial, and often avoided. The themes that emerged from this analysis support the utility of communication science and health behavior theories to better understand and improve PDA communication behaviors of both prescribers and pharmacists, and thereby improve engagement in PDA prevention and treatment

Adrenomedullin gene expression differences in mice do not affect blood pressure but modulate hypertension-induced pathology in males

Adrenomedullin (AM) is a potent vasodilator peptide in plasma at picomolar levels. Polymorphisms in the human AM gene have been associated with genetic predisposition to diabetic nephropathy and proteinuria with essential hypertension, and numerous studies have demonstrated that endogenous AM plays a role in protecting the heart and kidneys from fibrosis resulting from cardiovascular disease. Elevated plasma levels of AM are associated with pregnancy and sepsis and with cardiovascular stress and hypertension. However, there are no reports of the effects of genetic differences in the expression of the endogenous AM gene and of gender on blood pressure in these circumstances or on the pathological changes accompanying hypertension. To address these questions, we have generated mice having genetically controlled levels of AM mRNA ranging from ≈50% to ≈140% of wild-type levels. These modest changes in AM gene expression have no effect on basal blood pressure. Although pregnancy and sepsis increase plasma AM levels, genetically reducing AM production does not affect the transient hypotension that occurs during normal pregnancy or that is induced by treatment with lipopolysaccharide. Nor does the reduction of AM affect chronic hypertension caused by a renin transgene. However, 50% normal expression of AM enhances cardiac hypertrophy and renal damage in male, but not female, mice with a renin transgene. These observations suggest that the effect of gender on the role of AM in counteracting cardiovascular damage in humans merits careful evaluation

Social support and intimate partner violence in rural Pakistan: A longitudinal investigation of the bi-directional relationship

A large body of cross-sectional evidence finds strong and consistent associations between social support and intimate partner violence (IPV). However, the directionality of this relationship has not been firmly established due to a dearth of longitudinal evidence. Using cohort study data collected over a 3 year period from 945 women in rural Pakistan, we investigated the longitudinal relationship between IPV and social support. Friend and family social support was measured with the Multidimensional Perceived Social Support Scale, and IPV was measured with questions adopted from the World Health Organization's Violence Against Women Instrument, which was used to construct a measure of IPV severity. We estimated longitudinal associations in linear regression models that controlled for women's educational level, age at marriage, age, household composition, household assets, depressive symptoms, and Adverse Childhood Experiences. We found evidence of a bi-directional, mutually re-enforcing relationship that showed unique associations by type of social support. Specifically, we found that high social support from family, though not friends, decreased IPV severity 1 year later, and that higher IPV severity led to reductions in both friend and family social support 1 year later. Results suggest that interventions involving family members could be especially effective at reducing IPV in this context, and – given that low social support leads to many adverse health outcomes – results suggest that IPV can result in secondary harms due to diminished social support. In summary, our study confirms a bi-directional relationship between IPV and social support and suggests that IPV interventions that integrate social support may be especially effective at reducing IPV and mitigating secondary harms

Mother-in-law childcare and perinatal depression in rural Pakistan

Background: Mothers-in-law often provide key childcare support to daughters-in-law during the perinatal period that may enhance maternal mental health. Yet, poor mother-in-law/daughter-in-law relationships may be associated with maternal depression. The extent to which mother-in-law childcare involvement affects perinatal depression may differ across contexts of family conflict. Objective: We explored the relationship between mother-in-law childcare and daughter-in-law perinatal depression in rural Pakistan across contexts of family conflict. Methods: Data on 783 women came from the Bachpan Cohort, a birth cohort in Pakistan. Maternally-reported mother-in-law childcare was assessed at 3 and 12 months postpartum using a 24-h recall and categorized into no, low, and high involvement. Major depression was captured at 3 and 12 months using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders IV. Family conflict was captured using three items from the Life Events Checklist. Log-Poisson models were used to estimate cross-sectional associations between mother-in-law childcare and perinatal depression, stratified by family conflict. Results: Mother-in-law childcare was common in the first year postpartum. The association between mother-in-law childcare and perinatal depression differed by the presence of family conflict and postpartum timing. At 3?months postpartum, low and high mother-in-law childcare (vs no involvement) were associated with a lower prevalence of depression regardless of family conflict. At 12?months postpartum, among families with no conflict, low mother-in-law childcare (vs no involvement) was associated with lower perinatal depression; however, among families with conflict, high mother-in-law childcare was associated with increased perinatal depression. Conclusion: Our findings highlight the complexities of associations between mother-in-law childcare support and perinatal depression in the first year after birth. Mother-in-law childcare in the immediate postpartum period was beneficial for mothers. Understanding the source, amount, timing, and context of social support is necessary to inform research and interventions that aim to improve maternal mental health

The Day-in-the-Life method for assessing infant caregiving in rural Pakistan

Objective: This manuscript describes the Day-in-the-Life (DIL) method for assessing child caregiving activities, its implementation, and findings regarding family members' roles and associations with maternal depression symptoms. Background: Infant caregiving activities are most commonly performed by the mother, although there is increasing acknowledgement of others' contribution. Few methods exist to measure the diverse caregiving activities that mothers and others perform. Method: Method development occurred within the Bachpan Cohort Study in rural Pakistan (N = 1154 maternal–child dyads) when the child was 3 months old. The DIL was designed as a semi-structured interview in which the mother describes her child's day from their perspective. Regression analyses were then used to explore the correlation between the DIL and depression symptoms, using the Patient Health Questionnaire-9 (PHQ-9) measure. Results: The DIL method was easy to administer and displayed excellent interrater agreement. The findings indicated that instrumental caregiving was mostly provided by the mother alone, others in the household tended to contribute more to infant social interactions, and there was more support from others when the mother was less able to provide care (e.g., when ill). Depression symptoms were higher among women who experienced less contribution from family members when the mother was less able to provide care. Conclusions: The DIL can be deployed to measure infant caregiving activities and associations with maternal mental health. Implications: This method is promising for researchers interested in disentangling the contribution of multiple family members toward child caregiving and its impacts on maternal and child health