Observations on the vibration of axially-tensioned elastomeric pipes conveying fluids

A study of the effect of axial tension on the vibration of a single-span elastomeric pipe clamped at both ends conveying fluid has been carried out both experimentally and theoretically. A new mathematical model using a penalty function technique and the method of kinematic correction and fictitious loads has been developed. The influence of flowing fluid and axial tension on natural frequencies and mode shapes of the system has been described using this model and compared with experimental observations. Linear and non-linear dynamic response of the harmonically excited pipe has also been investigated for varying flow velocities and initial axial tensions

Increased systemic inflammation is associated with cardiac and vascular dysfunction over the first 12 weeks of antiretroviral therapy among undernourished, HIV-infected adults in Southern Africa.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.INTRODUCTION: Persistent systemic inflammation is associated with mortality among undernourished, HIV-infected adults starting antiretroviral therapy (ART) in sub-Saharan Africa, but the etiology of these deaths is not well understood. We hypothesized that greater systemic inflammation is accompanied by cardiovascular dysfunction over the first 12 weeks of ART. METHODS: In a prospective cohort of 33 undernourished (body mass index <18.5 kg/m2) Zambian adults starting ART, we measured C-reactive protein (CRP), tumor necrosis factor-α receptor 1 (TNF-α R1), and soluble CD163 and CD14 at baseline and 12 weeks. An EndoPAT device measured the reactive hyperemia index (LnRHI; a measure of endothelial responsiveness), peripheral augmentation index (AI; a measure of arterial stiffness), and heart rate variability (HRV; a general marker of autonomic tone and cardiovascular health) at the same time points. We assessed paired changes in inflammation and cardiovascular parameters, and relationships independent of time point (adjusted for age, sex, and CD4+ T-cell count) using linear mixed models. RESULTS: Serum CRP decreased (median change -3.5 mg/l, p=0.02), as did TNF-α R1 (-0.31 ng/ml, p<0.01), over the first 12 weeks of ART. A reduction in TNF-α R1 over 12 weeks was associated with an increase in LnRHI (p=0.03), and a similar inverse relationship was observed for CRP and LnRHI (p=0.07). AI increased in the cohort as a whole over 12 weeks, and a reduction in sCD163 was associated with a rise in the AI score (p=0.04). In the pooled analysis of baseline and 12 week data, high CRP was associated with lower HRV parameters (RMSSD, p=0.01; triangular index, p<0.01), and higher TNF- α R1 accompanied lower HRV (RMSSD, p=0.07; triangular index, p=0.06). CONCLUSIONS: Persistent inflammation was associated with impaired cardiovascular health over the first 12 weeks of HIV treatment among undernourished adults in Africa, suggesting cardiac events may contribute to high mortality in this population.This work was supported by the Vanderbilt Meharry Center for AIDS Research (NIH grant number P30 AI54999); the NIH Fogarty International Center, Office of the Director, National Institutes of Health, National Heart, Blood, and Lung Institute, and National Institute of Mental Health, through the Vanderbilt-Emory-Cornell-Duke Consortium for Global Health Fellows (grant number R25 TW009337); the National Center for Advancing Translational Sciences (CTSA award number UL1TR000445) and the European and Developing Countries Clinical Trials Partnership (grant IP.2009.33011.004)

The Importance of Social Cues for Discretionary Health Services Utilization: The Case of Infertility

Infertility is a discretionary health condition; although it carries with it important life course implications, treatment is rarely necessary for health reasons. Sociological theories of medical help-seeking emphasize demographic factors, perceived need, and enabling conditions in health services utilization, but we find that social cues are also strongly associated with health services utilization for infertility. Adjusted for conventional predictors of medical help-seeking, several social cue indicators have significant associations with utilization, including having friends and family with children, perceiving infertility stigma, and having a partner and/or family member who encourages treatment. Perceived need accounts for the largest portion of the variation in utilization. Enabling conditions explain less of the variance than social cues. Social cues should be especially important for discretionary health services utilization. Studies of service utilization for discretionary health conditions should explicitly incorporate a range of measures of social cues into their models

A New Way to Estimate the Potential Unmet Need for Infertility Services Among Women in the United States

Background: Fewer than 50% of women who meet the medical/behavioral criteria for infertility receive medical services. Estimating the number of women who both meet the medical/behavioral criteria for infertility and who have pro-conception attitudes will allow for better estimates of the potential need and unmet need for infertility services in the United States. Methods: The National Survey of Fertility Barriers was administered by telephone to a probability sample of 4,712 women in the United States. The sample for this analysis was 292 women who reported an experience of infertility within 3 years of the time of the interview. Infertile women were asked if they were trying to conceive at the time of their infertility experience and if they wanted to have a child to determine who could be considered in need of services. Results: Among U.S. women who have met medical criteria for infertility within the past three years, 15.9% report that they were neither trying to have a child nor wanted to have a child and can be classified as not in need of treatment. Of the 84.9% of infertile women in need of treatment, 58.1% did not even talk to a doctor about ways to become pregnant. Discussion: Even after taking into account that not all infertile women are in need of treatment, there is still a large unmet need for infertility treatment in the United States. Conclusion: Studies of the incidence of infertility should include measures of both trying to have a child and wanting to have a child

A New Way to Estimate the Potential Unmet Need for Infertility Services Among Women in the United States

Background: Fewer than 50% of women who meet the medical/behavioral criteria for infertility receive medical services. Estimating the number of women who both meet the medical/behavioral criteria for infertility and who have pro-conception attitudes will allow for better estimates of the potential need and unmet need for infertility services in the United States. Methods: The National Survey of Fertility Barriers was administered by telephone to a probability sample of 4,712 women in the United States. The sample for this analysis was 292 women who reported an experience of infertility within 3 years of the time of the interview. Infertile women were asked if they were trying to conceive at the time of their infertility experience and if they wanted to have a child to determine who could be considered in need of services. Results: Among U.S. women who have met medical criteria for infertility within the past three years, 15.9% report that they were neither trying to have a child nor wanted to have a child and can be classified as not in need of treatment. Of the 84.9% of infertile women in need of treatment, 58.1% did not even talk to a doctor about ways to become pregnant. Discussion: Even after taking into account that not all infertile women are in need of treatment, there is still a large unmet need for infertility treatment in the United States. Conclusion: Studies of the incidence of infertility should include measures of both trying to have a child and wanting to have a child

A New Way to Estimate the Potential Unmet Need for Infertility Services Among Women in the United States

Background: Fewer than 50% of women who meet the medical/behavioral criteria for infertility receive medical services. Estimating the number of women who both meet the medical/behavioral criteria for infertility and who have pro-conception attitudes will allow for better estimates of the potential need and unmet need for infertility services in the United States. Methods: The National Survey of Fertility Barriers was administered by telephone to a probability sample of 4,712 women in the United States. The sample for this analysis was 292 women who reported an experience of infertility within 3 years of the time of the interview. Infertile women were asked if they were trying to conceive at the time of their infertility experience and if they wanted to have a child to determine who could be considered in need of services. Results: Among U.S. women who have met medical criteria for infertility within the past three years, 15.9% report that they were neither trying to have a child nor wanted to have a child and can be classified as not in need of treatment. Of the 84.9% of infertile women in need of treatment, 58.1% did not even talk to a doctor about ways to become pregnant. Discussion: Even after taking into account that not all infertile women are in need of treatment, there is still a large unmet need for infertility treatment in the United States. Conclusion: Studies of the incidence of infertility should include measures of both trying to have a child and wanting to have a child

Measurements of Water Surface Snow Lines in Classical Protoplanetary Disks

We present deep Herschel-PACS spectroscopy of far-infrared water lines from a sample of four protoplanetary disks around solar-mass stars, selected to have strong water emission at mid-infrared wavelengths. By combining the new Herschel spectra with archival Spitzer-IRS spectroscopy, we retrieve a parameterized radial surface water vapor distribution from 0.1 to 100 au using two-dimensional dust and line radiative transfer modeling. The surface water distribution is modeled with a step model composed of a constant inner and outer relative water abundance and a critical radius at which the surface water abundance is allowed to change. We find that the four disks have critical radii of ~3–11 au, at which the surface water abundance decreases by at least 5 orders of magnitude. The measured values for the critical radius are consistently smaller than the location of the surface snow line, as predicted by the observed spectral energy distribution. This suggests that the sharp drop-off of the surface water abundance is not solely due to the local gas-solid balance, but may also be driven by the deactivation of gas-phase chemical pathways to water below 300 K. Assuming a canonical gas-to-dust ratio of 100, as well as coupled gas and dust temperatures T_(gas) = T_(dust), the best-fit inner water abundances become implausibly high (0.01–1.0 H_2^(-1)). Conversely, a model in which the gas and dust temperatures are decoupled leads to canonical inner-disk water abundances of ~10^(-4) H_(2)^(-1), while retaining gas-to-dust ratios of 100. That is, the evidence for gas–dust decoupling in disk surfaces is stronger than for enhanced gas-to-dust ratios

Relationship Satisfaction Among Infertile Couples: Implications of Gender and Self-Identification

We use path analysis to analyze heterosexual couples from the U.S. National Survey of Fertility Barriers, a probability-based sample of women and their male partners. We restrict the sample to couples in which the women are infertile. We estimate a path model of each partner’s relationship satisfaction on indicators of self-identifying as having a fertility problem or not at the individual and couple levels. We find a gender effect: for women, but not men, relationship satisfaction was significantly higher when neither partner self-identified as having a fertility problem. Women’s relationship satisfaction exerted a strong influence on their partners’ relationship satisfaction, but no similar association between men’s relationship satisfaction and their partner’s satisfaction was found. In infertile couples, higher levels of perceived social support are associated with higher levels of relationship satisfaction for women but not for men

The NRPD1 N-terminus contains a Pol IV-specific motif that is critical for genome surveillance in Arabidopsis

RNA-guided surveillance systems constrain the activity of transposable elements (TEs) in host genomes. In plants, RNA polymerase IV (Pol IV) transcribes TEs into primary transcripts from which RDR2 synthesizes double-stranded RNA precursors for small interfering RNAs (siRNAs) that guide TE methylation and silencing. How the core subunits of Pol IV, homologs of RNA polymerase II subunits, diverged to support siRNA biogenesis in a TE-rich, repressive chromatin context is not well understood. Here we studied the N-terminus of Pol IV’s largest subunit, NRPD1. Arabidopsis lines harboring missense mutations in this N-terminus produce wild-type (WT) levels of NRPD1, which co-purifies with other Pol IV subunits and RDR2. Our in vitro transcription and genomic analyses reveal that the NRPD1 N-terminus is critical for robust Pol IV-dependent transcription, siRNA production and DNA methylation. However, residual RNA-directed DNA methylation observed in one mutant genotype indicates that Pol IV can operate uncoupled from the high siRNA levels typically observed in WT plants. This mutation disrupts a motif uniquely conserved in Pol IV, crippling the enzyme's ability to inhibit retrotransposon mobilization. We propose that the NRPD1 N-terminus motif evolved to regulate Pol IV function in genome surveillance