15,554 research outputs found

    Elastic Foundations as Heterogeneous Adventitial Boundary Condition for the Assessment of Aortic Wall and Peri-Aortic Stiffness from Dense-MRI Data Using Inverse FEM Approach

    Get PDF
    Background: The establishment of in vivo, patient-specific, and regionally resolved techniques to quantify aortic properties is key for improving risk assessment in clinical practice and scientific understanding of cardiovascular growth and remodeling. Many in vivo studies quantify vascular stiffness using Pulse Wave Velocity. This method provides an averaged measure of stiffness for the entire aorta, ignoring variations in wall stiffness and boundary conditions. Previous studies using Displacement Encoding with Stimulated Echoes Magnetic Resonance Imaging (DENSE-MRI) suggested that the infrarenal abdominal aorta (IAA) deforms heterogeneously throughout the cardiac cycle. Method: Herein, we hypothesize that the aortic wall strain heterogeneity is driven in healthy aortas by adventitial tethering to perivascular tissues that can be modeled with elastic foundation boundary conditions (EFBC) using a collection of linear-springs with a circumferential distribution of stiffness. Nine healthy-human IAAs were modeled using patient-specific imaging and displacement fields from SSFP and DENSE MRI, followed by assessment of aortic wall properties and heterogeneous EFBC parameters using inverse Finite Element Method (FEM). Results: In contrast to traction-free boundary condition, prescription of EFBC reduced the nodal displacement error by 60% and reproduced the DENSE-derived strain distribution. Estimated aortic stiffness was in agreement with previously reported experimental test data. The distribution of normalized EFBC stiffness was consistent among all patients and spatially correlated to standard peri-aortic anatomical features. Conclusion: Results suggest that EFBCs can be generalized for human adults with normal anatomy. This approach is computationally inexpensive, making it ideal for large-population clinical research and incorporation into computational cardiovascular fluid-structure analyses.https://scholarscompass.vcu.edu/gradposters/1113/thumbnail.jp

    The Sub-Surface Structure of a Large Sample of Active Regions

    Full text link
    We employ ring-diagram analysis to study the sub-surface thermal structure of active regions. We present results using a large number of active regions over the course of Solar Cycle 23. We present both traditional inversions of ring-diagram frequency differences, with a total sample size of 264, and a statistical study using Principal Component Analysis. We confirm earlier results on smaller samples that sound speed and adiabatic index are changed below regions of strong magnetic field. We find that sound speed is decreased in the region between approximately r=0.99R_sun and r=0.995R_sun (depths of 3Mm to 7Mm), and increased in the region between r=0.97R_sun and r=0.985R_sun (depths of 11Mm to 21Mm). The adiabatic index is enhanced in the same deeper layers that sound-speed enhancement is seen. A weak decrease in adiabatic index is seen in the shallower layers in many active regions. We find that the magnitudes of these perturbations depend on the strength of the surface magnetic field, but we find a great deal of scatter in this relation, implying other factors may be relevant.Comment: 16 pages, 11 figures, accepted for publication in Solar Physic

    Household Dysfunction Is Associated With Bullying Behavior in 10-year-old Children: Do Socioeconomic Circumstances Matter?

    Get PDF
    This study measured the prevalence of bullying behavior in 10-year-old children and investigated the effect of the socioeconomic context on the impact of household dysfunction on bullying. We studied 5,338 members of the Portuguese Generation XXI birth cohort. Information on involvement in bullying, socioeconomic characteristics, and household dysfunction was collected by trained interviewers using structured questionnaires. Being a victim of bullying was reported by 14.4% of participants, being a bully by 1.4%, and being a bully-victim by 3.9%. Being a victim or both bully-victim, simultaneously, was more frequent among children from medium-high income families. Also, children from low-income families who reported household substance abuse, witnessed parents' intimate partner violence, and were victims of physical violence, were more frequently victims of bullying; and those who experienced family violence were more frequently involved as bully-victims. Among children from medium-high income families, all these household adversity experiences significantly increased the odds of being victim, bully, or bully-victim. Thus, although children from medium-high income families are less likely to experience adversity at home, when it happens, there is a greater effect on their behavior, suggesting that better socioeconomic circumstances do not seem to act as a protective factor.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the European Regional Development Fund (ERDF) through the Operational Programme Competitiveness and Internationalization and national funding from the Foundation for Science and Technology (FCT), Portuguese Ministry of Science, Technology and Higher Education under the projects “BioAdversity: How childhood social adversity shapes health: The biology of social adversity (POCI-01-0145-FEDER-016838; info:eu-repo/grantAgreement/FCT/9471 - RIDTI/PTDC/DTP-EPI/1687/2014/PT) and HIneC: When do health inequalities start? Understanding the impact of childhood social adversity on health trajectories from birth to early adolescence (POCI-01-0145-FEDER-029567; info:eu-repo/grantAgreement/FCT/9471 - RIDTI/info:eu-repo/grantAgreement/FCT/9471 - RIDTI/PTDC/SAU-PUB/29567/2017/PT017/PT)”; Unidade de Investigação em Epidemiologia - Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB/04750/2020/PT); Administração Regional de Saúde Norte (Regional Department of Ministry of Health) and Fundação Calouste Gulbenkian; PhD Grant info:eu-repo/grantAgreement/FCT/POR_NORTE/SFRH/BD/108742/2015/PT (to SS) co-funded by the FCT and Human Capital Operational Programme of the European Social Fund (POCH/FSE Program) and FCT Investigator contracts info:eu-repo/grantAgreement/FCT/CEEC IND 2017/CEECIND/01516/2017/CP1406/CT0001/PT (to SF)

    Erlang Code Evolution Control

    Full text link
    During the software lifecycle, a program can evolve several times for different reasons such as the optimisation of a bottle-neck, the refactoring of an obscure function, etc. These code changes often involve several functions or modules, so it can be difficult to know whether the correct behaviour of the previous releases has been preserved in the new release. Most developers rely on a previously defined test suite to check this behaviour preservation. We propose here an alternative approach to automatically obtain a test suite that specifically focusses on comparing the old and new versions of the code. Our test case generation is directed by a sophisticated combination of several already existing tools such as TypEr, CutEr, and PropEr; and other ideas such as allowing the programmer to chose an expression of interest that must preserve the behaviour, or the recording of the sequences of values to which this expression is evaluated. All the presented work has been implemented in an open-source tool that is publicly available on GitHub.Comment: Pre-proceedings paper presented at the 27th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur, Belgium, 10-12 October 2017 (arXiv:1708.07854

    Fourier Eigenfunctions, Uncertainty Gabor Principle and Isoresolution Wavelets

    Full text link
    Shape-invariant signals under Fourier transform are investigated leading to a class of eigenfunctions for the Fourier operator. The classical uncertainty Gabor-Heisenberg principle is revisited and the concept of isoresolution in joint time-frequency analysis is introduced. It is shown that any Fourier eigenfunction achieve isoresolution. It is shown that an isoresolution wavelet can be derived from each known wavelet family by a suitable scaling.Comment: 6 pages, XX Simp\'osio Bras. de Telecomunica\c{c}\~oes, Rio de Janeiro, Brazil, 2003. Fixed typo

    A note on the essential numerical range of block diagonal operators

    Get PDF
    In this note we characterize the essential numerical range of a block diagonal operator T = ⊕i T_i in terms of the numerical ranges {W (T_i )}i of its components. Specifically, the essential numerical range of T is the convex hull of the limit superior of {W (Ti )}i . This characterization can be simplified further. In fact, we prove the existence of a decomposition of T for which the convex hull is not required.info:eu-repo/semantics/acceptedVersio

    Early socioeconomic circumstances and cardiometabolic health in 10-year-old children

    Get PDF
    Background Social adversity is thought to become biologically embedded during sensitive periods of development, setting children on a trajectory of increased risk for later chronic diseases. Thus, social differences are expected to be expressed as biological alterations and might have their origins in early life. Therefore, we aim to estimate the association between early socioeconomic position (SEP) and cardiometabolic health during childhood. Methods Data from 2962 participants in the population-based birth cohort Generation XXI, from Porto, Portugal, was collected following standardized procedures at all study waves. Early SEP definition included household income, parental education and occupation at child’s birth. Cardiometabolic health was characterized at the age of 7 and 10, considering the triglycerides, cholesterol, fasting glucose, body mass index, systolic and diastolic blood pressure. Logistic regression was used to estimate the association between early SEP and a favorable cardiometabolic health profile. Results A favorable cardiometabolic profile was observed in almost half of participants at both ages, particularly among high SEP children who remain more frequently without alterations. For girls, higher paternal education at 7 years (OR:1.49;95%CI:1.03-2.15) and higher SEP at 10 were associated with better cardiometabolic health profile. In boys, a better cardiometabolic health profile was observed with increasing levels in maternal and paternal education and occupation, but at the age of 10, social differences were more evident according to parental education. Conclusions We provide evidence that children from more advantaged SEP at birth have an increased likelihood of presenting better cardiometabolic health at early ages. Social differences in cardiometabolic health biomarkers are already found in childhood, suggesting that the short-term impact of early life SEP on the physiology dysregulation takes place already in the first decade of life

    Early socioeconomic circumstances and adverse childhood experiences in 10-year-old children

    Get PDF
    Background Evidence showed that adverse childhood experiences (ACEs) are associated with the development of disease later in life and premature death. Examining the occurrence of these experiences at early ages would contribute to intervene and therefore to reduce health inequalities. This study aimed to assess the prevalence of ACEs among 10-year-children and to examine its association with early socioeconomic circumstances. Methods At the fourth wave of the population-based birth cohort Generation XXI, from Porto, Portugal, 5153 children completed a self-report questionnaire on 9 experiences related to household dysfunction and physical and emotional abuse. Socioeconomic circumstances included household income, maternal and paternal education, and history of parental unemployment. Logistic regression was performed to calculate the Odds Ratios (OR) and 95% Confidence Intervals (95%CI). Results A high prevalence of physical and emotional abuse was reported by children from low socioeconomic circumstances. A graded relationship between socioeconomic circumstances and cumulative ACEs was observed, for instance, low household income was associated with increased number of ACEs (one event [OR = 1.10; 95%CI: 0.89-1.36], two events [OR = 1.41; 95%CI: 1.15-1.73], three events [OR = 1.67; 95%CI: 1.34-2.06], and four or more events [OR = 2.05; 95%CI: 1.64-2.55]). Also, living with one parent or none of them increased the likelihood of reporting multiple ACEs (OR = 5.50; 95%CI: 4.23-7.13). Conclusions Children from low socioeconomic circumstances were more likely to report multiple adverse experiences in the first decade of life. These findings support that children from less advantaged environments might be at a higher risk of co-occurrence of adverse experiences during their childhood
    corecore