Associations between Childhood Body Size, Composition, Blood Pressure and Adult Cardiac Structure: The Fels Longitudinal Study

Objectives To determine whether childhood body size, composition and blood pressure are associated with adult cardiac structure by estimating childhood “age of divergence.” Methods 385 female and 312 male participants in the Fels Longitudinal Study had echocardiographic measurements of left ventricular mass, relative wall thickness, and interventricular septal thickness. Also available were anthropometric measurements of body mass index, waist circumference, percentage body fat, fat free mass, total body fat, and systolic and diastolic blood pressures, taken in both childhood and adulthood. The age of divergence is estimated as the lowest age at which childhood measurements are significantly different between patients with low and high measurements of adult cardiac structure. Results Childhood body mass index is significantly associated with adult left ventricular mass (indexed by height) in men and women (ages of divergence: 7.5 years and 11.5 years, respectively), and with adult interventricular septal thickness in boys (age of divergence: 9 years). Childhood waist circumference indexed by height is associated with left ventricular mass (indexed by height) in boys (age of divergence: 8 years). Cardiac structure was in general not associated with childhood body composition and blood pressure. Conclusions Though results are affected by adult body size, composition and blood pressure, some aspects of adult cardiac structure may have their genesis in childhood body size

Solar sail capture trajectories at Mercury

Mercury is an ideal environment for future planetary exploration by solar sail since it has proved difficult to reach with conventional propulsion and hence remains largely unexplored. In addition, its proximity to the Sun provides a solar sail acceleration of order ten times the sail characteristic acceleration at 1 AU. Conventional capture techniques are shown to be unsuitable for solar sails and a new method is presented. It is shown that capture is bound by upper and lower limits on the orbital elements of the approach orbit and that failure to be within limits results in a catastrophic collision with the planet. These limits are presented for a range of capture inclinations and sail characteristic accelerations. It is found that sail hyperbolic excess velocity is a critical parameter during capture at Mercury, with only a narrow allowed band in order to avoid collision with the planet. The new capture methodis demonstrated for a Mercury sample return mission

Deep learning for synthetic microstructure generation in a materials-by-design framework for heterogeneous energetic materials

The sensitivity of heterogeneous energetic (HE) materials (propellants, explosives, and pyrotechnics) is critically dependent on their microstructure. Initiation of chemical reactions occurs at hot spots due to energy localization at sites of porosities and other defects. Emerging multi-scale predictive models of HE response to loads account for the physics at the meso-scale, i.e. at the scale of statistically representative clusters of particles and other features in the microstructure. Meso-scale physics is infused in machine-learned closure models informed by resolved meso-scale simulations. Since microstructures are stochastic, ensembles of meso-scale simulations are required to quantify hot spot ignition and growth and to develop models for microstructure-dependent energy deposition rates. We propose utilizing generative adversarial networks (GAN) to spawn ensembles of synthetic heterogeneous energetic material microstructures. The method generates qualitatively and quantitatively realistic microstructures by learning from images of HE microstructures. We show that the proposed GAN method also permits the generation of new morphologies, where the porosity distribution can be controlled and spatially manipulated. Such control paves the way for the design of novel microstructures to engineer HE materials for targeted performance in a materials-by-design framework

History of Being in Government Care Associated with Younger Age at Injection Initiation Among a Cohort of Street-involved Youth

Introduction and Aims: Compared to the general population of youth, health-related disparities experienced by youth exposed to the child welfare system are well documented. Amongst these vulnerabilities are elevated rates of substance use, including injection drug use; however, less is known about when these youth transition to this high-risk behaviour. We sought to assess whether having a history of government care is associated with initiating injection drug use before age 18.   Design and Methods: Between September 2005 and May 2014, data were derived from the At-Risk Youth Study, a cohort of street-involved youth who use illicit drugs in Vancouver, Canada. Multivariable logistic regression analysis was employed to examine the relationship between early initiation of injection drug use and having a history of being in government care.   Results: Among the 581 injecting street-involved youth included, 229 (39%) reported initiating injection drug use before 18 years of age. In multivariable analysis, despite controlling for a range of potential confounders, having a history of government care remained significantly associated with initiating injection drug use before age 18 (adjusted odds ratio = 1.69; 95% confidence interval: 1.15–2.48).   Discussion and Conclusions: Youth with a history of being in government care were significantly more likely to initiate injection drug use before age 18 than street-involved youth without a history of being in care. These findings imply that youth in the child welfare system are at higher-risk and suggest interventions are needed to prevent transitions into high-risk substance use among this population

Association between first-year virological response to raltegravir and long-term outcomes in treatment-experienced patients with HIV-1 infection

Background: We explored the relationship between virological response in the first year of treatment and long-term outcomes in the BENCHMRK studies. Methods: Patients failing antiretroviral treatment with 3-class resistant HIV-1 received double-blinded raltegravir (or placebo) with optimized background therapy (OBT) until week 156, followed by open-label raltegravir with OBT up to week 240. In this exploratory analysis of patients randomized to raltegravir, virological response over weeks 16-48 was categorized as continuous suppression (CS; viral RNA [vRNA] always 50 copies/ml at least once), or not suppressed (NS; vRNA >400 copies/ml at least once). The association between these first-year vRNA response categories and baseline factors was analysed with univariate and multivariate models. Virological and immunological outcomes for years 2-5 were assessed by first-year vRNA response category (observed failure approach). Results: Baseline vRNA, baseline CD4(+) T-cell count and rapid viral decay (vRNA <50 copies/ml between weeks 2-12) correlated with first-year vRNA response (P<0.001); only rapid viral decay remained significant by multiple regression. Virological response rates were similar in the LLV and CS groups and lowest in the NS group. CD4(+) T-cell count increased through week 240 in the CS and LLV groups. Time to loss of virological response (confirmed vRNA ≥400 copies/ml) through week 240 did not support as strong a difference between the LLV and CS groups (log-rank P=0.11) as previously reported through weeks 156 and 192 (P<0.05). Conclusions: Treatment-experienced patients on a raltegravir-based regimen with early LLV may have long-term virological and immunological benefit when their therapy is maintained

Digital search trees and chaos game representation

Version préliminaire (2006) d'un travail publié sous forme définitive (2009).International audienceIn this paper, we consider a possible representation of a DNA sequence in a quaternary tree, in which on can visualize repetitions of subwords. The CGR-tree turns a sequence of letters into a digital search tree (DST), obtained from the suffixes of the reversed sequence. Several results are known concerning the height and the insertion depth for DST built from i.i.d. successive sequences. Here, the successive inserted wors are strongly dependent. We give the asymptotic behaviour of the insertion depth and of the length of branches for the CGR-tree obtained from the suffixes of reversed i.i.d. or Markovian sequence. This behaviour turns out to be at first order the same one as in the case of independent words. As a by-product, asymptotic results on the length of longest runs in a Markovian sequence are obtained

Needs & networks: understanding the role and impact of social networks on HIV (self-)testing among GBMSM and trans people in England and Wales

Background: Understanding how HIV self-testing (HIVST) can meet the testing needs of gay, bisexual and other men who have sex with men (GBMSM) and trans people whose social networks vary is key to upscaling HIVST implementation. We aim to develop a contextual understanding of social networks and HIV testing needs among GBMSM (cis and transgender) and trans women in SELPHI (An HIV Self-testing Public Health Intervention), the UK’s largest randomised trial on HIVST. Methods: This study re-analysed qualitative interviews conducted from 2015 to 2020. Forty-three in-person interviews were thematically analysed using the Framework Method. Our analytic matrix inductively categorised participants based on the unmet needs for HIV testing and the extent of social network support. The role of social networks on HIVST behaviour was explored based on individuals’ testing trajectories. Results: Four distinct groups were identified based on their unmet testing needs and perceived support from social networks. Optimisation advocates (people with high unmet needs and with high network support, n=17) strived to tackle their remaining barriers to HIV testing through timely support and empowerment from social networks. Privacy seekers (people with high unmet needs and with low network support, n=6) prioritised privacy because of perceived stigma. Opportunistic adopters (people with low unmet needs and with high network support, n=16) appreciated social network support and acknowledged socially privileged lives. Resilient testers (people with low unmet needs and with low network support, n=4) might hold potentially disproportionate confidence in managing HIV risks without sustainable coping strategies for potential seroconversion. Supportive social networks can facilitate users’ uptake of HIVST by: (1) increasing awareness and positive attitudes towards HIVST, (2) facilitating users’ initiation into HIVST with timely support and (3) affording participants an inclusive space to share and discuss testing strategies. Conclusions: Our proposed categorisation may facilitate the development of differentiated person-centred HIVST programmes. HIVST implementers should carefully consider individuals’ unmet testing needs and perceived levels of social support, and design context-specific HIVST strategies that link people lacking supportive social networks to comprehensive HIV care

Engineering Analysis Studies for Preliminary Design of Lightweight Cryogenic Hydrogen Tanks in UAV Applications

A series of engineering analysis studies were conducted to investigate the potential application of nanoclay-enhanced graphite/epoxy composites and polymer cross-linked silica aerogels in cryogenic hydrogen storage tank designs. This assessment focused on the application of these materials in spherical tank designs for unmanned aeronautic vehicles with mission durations of 14 days. Two cryogenic hydrogen tank design concepts were considered: a vacuum-jacketed design and a sandwiched construction with an aerogel insulating core. Analyses included thermal and structural analyses of the tank designs as well as an analysis of hydrogen diffusion to specify the material permeability requirements. The analyses also provided material property targets for the continued development of cross-linked aerogels and nanoclay-enhanced graphite/epoxy composites for cryogenic storage tank applications. The results reveal that a sandwiched construction with an aerogel core is not a viable design solution for a 14-day mission. A vacuum-jacketed design approach was shown to be far superior to an aerogel. Aerogel insulation may be feasible for shorter duration missions. The results also reveal that the application of nanoclay-enhanced graphite/epoxy should be limited to the construction of outer tanks in a vacuum-jacketed design, since a graphite/epoxy inner tank does not provide a significant weight savings over aluminum and since the ability of nanoclay-enhanced graphite/epoxy to limit hydrogen permeation is still in question