Existence of global strong solutions to a beam-fluid interaction system

We study an unsteady non linear fluid-structure interaction problem which is a simplified model to describe blood flow through viscoleastic arteries. We consider a Newtonian incompressible two-dimensional flow described by the Navier-Stokes equations set in an unknown domain depending on the displacement of a structure, which itself satisfies a linear viscoelastic beam equation. The fluid and the structure are fully coupled via interface conditions prescribing the continuity of the velocities at the fluid-structure interface and the action-reaction principle. We prove that strong solutions to this problem are global-in-time. We obtain in particular that contact between the viscoleastic wall and the bottom of the fluid cavity does not occur in finite time. To our knowledge, this is the first occurrence of a no-contact result, but also of existence of strong solutions globally in time, in the frame of interactions between a viscous fluid and a deformable structure

Early adolescent disclosure and parental knowledge regarding online activities: Social anxiety and parental rule-setting as moderators

Early adolescents spend a lot of time online, yet little is currently known about the links between parental rule-setting, adolescent disclosure about online activities, and whether social anxiety may interfere with these processes. Using a longitudinal sample of 526 adolescents (269 girls; Mage = 14.00) and their parents (79% mothers, Mage = 43.66), the results from the current study showed low correspondence between parental knowledge, adolescent disclosure, as well as parents’ and adolescents’ ratings of parental legitimacy to set boundaries about online activities. High social anxiety interacted with high adolescent-rated parental rule-setting in predicting the least disclosure about chatting with strangers and posting online content over time. Also, high social anxiety interacted with low parent-rated control to predict more adolescent disclosure about chatting with strangers and money spent online over time. Thus, social anxiety and parental rule-setting moderated the links between disclosure and knowledge for some early adolescent online activities. Our results conflict with the value typically placed on parental rule-setting in online contexts, at least for socially anxious adolescents

School-based intervention to improve the mental health of low-income, secondary school students in Santiago, Chile (YPSA): study protocol for a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Depression is common and can have devastating effects on the life of adolescents. Psychological interventions are the first-line for treating or preventing depression among adolescents. This proposal aims to evaluate a school-based, universal psychological intervention to reduce depressive symptoms among student's aged 13-14 attending municipal state secondary schools in Santiago, Chile.</p> <p>Study design</p> <p>This is a cluster randomised controlled trial with schools as the main clusters. We compared this intervention with a control group in a study involving 22 schools, 66 classes and approximately 2,600 students. Students in the active schools attended 11 weekly and 3 booster sessions of an intervention based on cognitive-behavioural models. The control schools received their usual but enhanced counselling sessions currently included in their curriculum. Mean depression scores and indicators of levels of functioning were assessed at 3 and 12 months after the completion of the intervention in order to assess the effectiveness of the intervention. Direct and indirect costs were measured in both groups to assess the cost-effectiveness of this intervention.</p> <p>Discussion</p> <p>As far as we are aware this is the first cluster randomised controlled trial of a school intervention for depression among adolescents outside the Western world.</p> <p>Trial Registration</p> <p><a href="http://www.controlled-trials.com/ISRCTN19466209">ISRCTN19466209</a></p

Latent Class Analysis of Antisocial Behavior: Interaction of Serotonin Transporter Genotype and Maltreatment

To improve understanding about genetic and environmental influences on antisocial behavior (ASB), we tested the association of the 44-base pair polymorphism of the serotonin transporter gene (5-HTTLPR) and maltreatment using latent class analysis in 2,488 boys and girls from Wave 1 of the National Longitudinal Study of Adolescent Health. In boys, ASB was defined by three classes (Exclusive Covert, Mixed Covert and Overt, and No Problems) whereas in girls, ASB was defined by two classes (Exclusive Covert, No Problems). In boys, 5-HTTLPR and maltreatment were not significantly related to ASB. However, in girls, maltreatment, but not 5-HTTLPR, was significantly associated with ASB. A significant interaction between 5-HTTLPR and maltreatment was also observed, where maltreated girls homozygous for the short allele were 12 times more likely to be classified in the Exclusive Covert group than in the No Problems group. Structural differences in the latent structure of ASB at Wave 2 and Wave 3 prevented repeat LCA modeling. However, using counts of ASB, 5-HTTLPR, maltreatment, and its interaction were unrelated to overt and covert ASB at Wave 2 and only maltreatment was related to covert ASB at Wave 3. We discuss these findings within the context of sex differences in ASB and relevant models of gene-environment interplay across developmental periods

Parameter estimation and mathematical modeling for the quantitative description of therapy failure due to drug resistance in gastrointestinal stromal tumor metastasis to the liver

In this work we develop a general mathematical model and devise a practical identifiability approach for gastrointestinal stromal tumor (GIST) metastasis to the liver, with the aim of quantitatively describing therapy failure due to drug resistance. To this end, we have modeled metastatic growth and therapy failure produced by resistance to two standard treatments based on tyrosine kinase inhibitors (Imatinib and Sunitinib) that have been observed clinically in patients with GIST metastasis to the liver. The parameter identification problem is difficult to solve, since there are no general results on this issue for models based on ordinary differential equations (ODE) like the ones studied here. We propose a general modeling framework based on ODE for GIST metastatic growth and therapy failure due to drug resistance and analyzed five different model variants, using medical image observations (CT scans) from patients that exhibit drug resistance. The associated parameter estimation problem was solved using the Nelder-Mead simplex algorithm, by adding a regularization term to the objective function to address model instability, and assessing the agreement of either an absolute or proportional error in the objective function. We compared the goodness of fit to data for the proposed model variants, as well as evaluated both error forms in order to improve parameter estimation results. From the model variants analyzed, we identified the one that provides the best fit to all the available patient data sets, as well as the best assumption in computing the objective function (absolute or proportional error). This is the first work that reports mathematical models capable of capturing and quantitatively describing therapy failure due to drug resistance based on clinical images in a patient-specific manner

Predictive factors of stenosis after stapled colorectal anastomosis: Prospective analysis of 179 consecutive patients

The incidence, risk factors, and clinical relevance of stenosis of stapled colorectal anastomosis (CRA) were studied prospectively. Anastomotic stricture was defined as the inability of traversing the anastomosis with the rigid proctoscope. The population studied consisted of 179 patients (94 males) with an average age of 59.3 years (range: 20 to 91 years). The main indication for surgery was colorectal cancer in 59% of the cases, followed by diverticular disease in 23%. The first endoscopic control was performed before 4 months in 25% of the patients, between 5 and 10 months in 50%, and during the following 10 months in 25%. Stenosis was verified with the rigid instrument in 21.1% of the cases and with the flexible colonoscope in 4.4%. The barium enema performed in 12 cases confirmed a punctiform stenosis in 5 patients, 4 of whom had been asymptomatic. An endoscopic dilatation was performed on 5 of the 8 symptomatic patients, with one relapse that required an additional dilatation. I

Chilean adolescents\u27 beliefs about the legitimacy of parental authority: Individual and age-related differences

Individual and age-related differences in the patterning of adolescents’ beliefs about the legitimacy of parental authority were examined in a sample of 3425 Chilean adolescents (Mage = 15.0). During early, middle, and late adolescence, three analogous patterns of beliefs about the legitimacy of parental authority were identified using latent class analysis (LCA). Youth in the Parental Control class ceded parents legitimate control over issues in the multi-faceted and prudential domains and were relatively likely to cede parental control over the personal domain. Those in the Shared Control class differentiated the prudential from other domains. Those in the Personal Control class denied parents legitimate authority over issues in all domains. Within analogous classes, younger adolescents were more likely to grant parents legitimate authority than older adolescents. Results are consistent with prior research documenting age-related differences, but raise important questions about the normative nature of age-related change in legitimacy beliefs. The advantages of studying sub-groups and variability in the patterning of legitimacy beliefs are discussed