548 research outputs found

    Stress-dependent generalized Prandtl–Ishlinskii hysteresis model of a NiTi wire with superelastic behavior

    Get PDF
    The extremely useful superelastic behavior of NiTi has been poorly explored because of the limited number of models that can describe the complete hysteretic behavior of NiTi, including a superelastic condition that strongly depends on the applied stress. This paper presents the development of a stress-dependent phenomenological model of NiTi by modifying the existing generalized Prandtl–Ishlinskii (GPI) model. The parameters of the envelop function of the GPI model’s play operator are reformulated as quadratic functions of the applied stress. The stress-dependent GPI model can satisfactorily predict the output strain of a NiTi #6 wire under temperature and stress variation

    5-Year Follow-Up of a Telephone Intervention to Increase Fruit and Vegetable Consumption in Preschoolers: The ‘Healthy Habits’ Cluster Randomised Trial

    Full text link
    Little is known about the long-term impact of telephone-based interventions to improve child diet. This trial aimed to assess the long-term effectiveness (after 5 years) of a telephone-based parent intervention in increasing children’s fruit and vegetable consumption. Parents of 3–5 year olds were recruited from 30 Australian preschools to participate in a cluster randomised controlled trial. Intervention parents received four, weekly, 30-min support calls aimed at modifying the home food environment. Control parents received printed materials. Consumption was assessed using the Fruit and Vegetable subscale of the Children’s Dietary Questionnaire (F&V-CDQ) (children) and daily servings of fruit and vegetables (children and parents) via parent telephone interview. Of the 394 parents who completed baseline, 57% (99 intervention, 127 control) completed follow-up. After 5-years, higher intervention F&V-CDQ scores, bordering on significance, were found in complete-case (+1.1, p = 0.06) and sensitivity analyses (+1.1, p = 0.06). There was no difference in parent or child consumption of daily fruit servings. Complete-case analysis indicated significantly higher consumption of child vegetable servings (+0.5 servings; p = 0.02), which was not significant in sensitivity analysis (+0.5 servings; p = 0.10). This telephone-based parent intervention targeting the family food environment may yield promising improvements in child fruit and vegetable consumption over a 5-year period

    Local Structure of Multiferroic TbMn2O5: Evidence for an Anomalous Terbium Oxygen Distribution

    Full text link
    The temperature dependent local structure of TbMn2O5 was determined by x-ray absorption spectroscopy. An anomalous Tb-O distribution is found. At high temperature it is broad but resolves into two distinct peaks below approximately 180 K. The distributions sharpen below the Tb magnetic ordering temperature (approximately 10 K). The distortions in the Tb-O distribution, away from the Pbam structure, are consistent with rotations of the MnOx polyhedra about the c-axis and suggest that Tb-O bond polarization may play a significant role in the observed ferroelectric properties of this system.Comment: 7 Figure

    Prolonged febrile seizures cause reversible reductions in white matter integrity

    Get PDF
    AbstractProlonged febrile seizures (PFS) are the commonest cause of childhood status epilepticus and are believed to carry a risk of neuronal damage, in particular to the mesial temporal lobe. This study was designed to determine: i) the effect of prolonged febrile seizures on white matter and ii) the temporal evolution of any changes seen.33 children were recruited 1month following PFS and underwent diffusion tensor imaging (DTI) with repeat imaging at 6 and 12months after the original episode of PFS. 18 age-matched healthy control subjects underwent similar investigations at a single time point. Tract-based spatial statistics (TBSS) was used to compare fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) between patients and controls on a voxel-wise basis within the white matter skeleton.Widespread reductions in FA along multiple white matter tracts were found at 1 and 6months post-PFS, but these had resolved at 12months. At one month post-PFS the main changes seen were reductions in AD but at 6months these had predominantly changed to increases in RD.These widespread white matter changes have not previously been noted following PFS. There are many possible explanations, but one plausible hypothesis is that this represents a temporary halting of normal white matter development caused by the seizure, that then resumes and normalises in the majority of children

    Accuracy of Digital Breast Tomosynthesis for Depicting Breast Cancer Subgroups in a UK Retrospective Reading Study (TOMMY Trial)

    Get PDF
    Purpose To compare the diagnostic performance of two-dimensional (2D) mammography, 2D mammography plus digital breast tomosynthesis (DBT), and synthetic 2D mammography plus DBT in depicting malignant radiographic features. Materials and Methods In this multicenter, multireader, retrospective reading study (the TOMMY trial), after written informed consent was obtained, 8869 women (age range, 29–85 years; mean, 56 years) were recruited from July 2011 to March 2013 in an ethically approved study. From these women, a reading dataset of 7060 cases was randomly allocated for independent blinded review of (a) 2D mammography images, (b) 2D mammography plus DBT images, and (c) synthetic 2D mammography plus DBT images. Reviewers had no access to results of previous examinations. Overall sensitivities and specificities were calculated for younger women and those with dense breasts. Results Overall sensitivity was 87% for 2D mammography, 89% for 2D mammography plus DBT, and 88% for synthetic 2D mammography plus DBT. The addition of DBT was associated with a 34% increase in the odds of depicting cancer (odds ratio [OR] = 1.34, P = .06); however, this level did not achieve significance. For patients aged 50–59 years old, sensitivity was significantly higher (P = .01) for 2D mammography plus DBT than it was for 2D mammography. For those with breast density of 50% or more, sensitivity was 86% for 2D mammography compared with 93% for 2D mammography plus DBT (P = .03). Specificity was 57% for 2D mammography, 70% for 2D mammography plus DBT, and 72% for synthetic 2D mammography plusmDBT. Specificity was significantly higher than 2D mammography (P < .001in both cases) and was observed for all subgroups (P < .001 for all cases). Conclusion The addition of DBT increased the sensitivity of 2D mammography in patients with dense breasts and the specificity of 2D mammography for all subgroups. The use of synthetic 2D DBT demonstrated performance similar to that of standard 2D mammography with DBT. DBT is of potential benefit to screening programs, particularly in younger women with dense breasts. © RSNA, 2015The TOMMY Trial (a comparison of digital breast tomosynthesis with mammography in the UK Breast Screening Programme) was supported by the NIHR Health Technology Assessment Programme.This is the final published version of the article. It was originally published in Radiology (Gilbert et al., Radiology, 2015, doi:10.1148/radiol.2015142566). The final version is available at http://dx.doi.org/10.1148/radiol.201514256
    • …
    corecore