1,472 research outputs found

    Surge motion of an ice floe in waves: comparison of theoretical and experimental models

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    A theoretical model and an experimental model of surge motions of an ice floe due to regular waves are presented. The theoretical model is a modified version of Morrison's equation, valid for small floating bodies. The experimental model is implemented in a wave basin at scale 1:100, using a thin plastic disk to model the floe. The processed experimental data displays a regime change in surge amplitude when the incident wavelength is approximately twice the floe diameter. It is shown that the theoretical model is accurate in the large wavelength regime, but highly inaccurate for the small wavelength regime.Comment: 11 pages, 10 figure

    Error analysis of an extended discontinuous galerkin method for highly-oscillatory problems

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    In this report we introduce an extended discontinuous Galerkin (XDG) method. Our XDG scheme is based on the Babuska-Zlamal approach and we apply it to a class of prototype elliptic boundary value problems that have solutions consisting of smooth functions perturbed by a set of high frequency modes which occupy a narrow band. The XDG scheme we study is enriched by trigonometric functions that cover the range of these perturbations. A theoretical error analysis is provided that shows the method converges and gives specifics on its accuracy. Computations with the XDG scheme further demonstrate the efficacy of this approach

    Regression modeling of longitudinal binary outcomes with outcome-dependent observation times

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    Conventional longitudinal data analysis methods assume that outcomes are independent of the data-collection schedule. However, the independence assumption may be violated, for example, when adverse events trigger additional physician visits in between prescheduled follow-ups. Observation times may therefore be associated with outcome values, which may introduce bias when estimating the eect of covariates on outcomes using standard longitudinal regression methods. Existing semi-parametric methods that accommodate outcome-dependent observation times are limited to the analysis of continuous outcomes. We develop new methods for the analysis of binary outcomes, while retaining the exibility of semi-parametric models. Our methods are based on counting process approaches, rather than relying on possibly intractable likelihood-based or pseudo-likelihood-based approaches, and provide marginal, population-level inference. In simulations, we evaluate the statistical properties of our proposed methods. Comparisons are made to \u27naive\u27 GEE approaches that either do not account for outcome-dependent observation times or incorporate weights based on the observation-time process. We illustrate the utility of our proposed methods using data from a randomized controlled trial of interventions designed to improve adherence to warfarin therapy. We show that our method performs well in the presence of outcome-dependent observation times, and provide identical inference to \u27naive\u27 approaches when observation times are not associated with outcomes

    Integration of scRNA-Seq and TCGA RNA-Seq to Analyze the Heterogeneity of HPV+ and HPV- Cervical Cancer Immune Cells and Establish Molecular Risk Models

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    Background: Numerous studies support that Human papillomavirus (HPV) can cause cervical cancer. However, few studies have surveyed the heterogeneity of HPV infected or uninfected (HPV+ and HPV-) cervical cancer (CESC) patients. Integration of scRNA-seq and TCGA data to analyze the heterogeneity of HPV+ and HPV- cervical cancer patients on a single-cell level could improve understanding of the cellular mechanisms during HPV-induced cervical cancer. Methods: CESC scRNA-seq data obtained from the Gene Expression Omnibus (GEO) database and the Seurat, Monocle3 package were used for scRNA-seq data analysis. The ESTIMATE package was used for single-sample gene immune score, CIBERSORT package was used to identify immune scores of cells, and the “WGCNA” package for the weighted correlation network analysis. Univariate Cox and LASSO regression were performed to establish survival and relapse signatures. KEGG and GO analyses were performed for the signature gene. Gene Expression Profiling Interactive Analysis was used for Pan-cancer analysis. Results: In the HPV+ CESC group, CD8+ T cells and B cells were down-regulated, whereas T reg cells, CD4+ T cells, and epithelial cells were up-regulated according to scRNA-seq data. Survival analysis of TCGA-CESC revealed that increased expression of naive B cells or CD8+ T cells favors the survival probability of CESC patients. WGCNA, univariate Cox, and LASSO Cox regression established a 9-genes survival signature and a 7-gene relapse model. Pan-cancer analysis identified IKZF3, FOXP3, and JAK3 had a similar distribution and effects in HPV-associated HNSC. Conclusion: Analysis of scRNA-seq and bulk RNA-seq of HPV+ and HPV- CESC samples revealed heterogeneity from transcriptional state to immune infiltration. Survival and relapse models were adjusted according to the heterogeneity of HPV+ and HPV- CESC immune cells to assess the prognostic risk accurately. Hub genes represent similar protection in HPV- associated HNSC while showing irrelevant to other potential HPV-related cancer

    Are Formal and Informal Home Mindfulness Practice Quantities Associated With Outcomes? Results From a Pilot Study of a Four-Week Mindfulness Intervention for Chronic Pain Management

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    Background The association between home mindfulness practice quantity in standard length mindfulness-based interventions (MBIs) and chronic pain outcomes is variable. Few studies focus on abbreviated MBIs (< 8 weeks) and distinguish between formal guided practices and informal practices in daily life. Objectives To characterize home mindfulness practice and explore associations between home practice quantity and pre-to-post-outcome changes after an MBI for chronic pain. Methods In this single-arm study, 21 adults with chronic pain (mean age = 54 years, 81% White, mean pain duration = 7 years) completed an MBI with four weekly group sessions. Pre and post self-report measures of pain intensity/interference, physical function, depression, anxiety, positive affect, sleep disturbance (all PROMIS measures), and pain acceptance, catastrophizing, perceived stress and mindfulness were completed, along with daily surveys of formal (mindfulness of breath, body scan) and informal (breathing space, mindfulness of daily activities) practice. Bivariate correlations and multivariable regression models were used to assess the association between days and minutes of practice and change in outcomes. Results On average, formal practice was completed on 4.3 days per week and 13.5 minutes per day. Informal practice was completed on 3.5 days per week and 8.6 minutes per day. Formal practice was not significantly correlated with outcomes (Spearman’s ρ = |.01|-|.32|), whereas informal practice was correlated with multiple outcomes (ρ = |.04|-|.66|). Number of days practiced informally was associated with improved pain interference, physical function, sleep disturbance, and catastrophizing (p’s ≀ .05). Number of minutes practiced informally was associated with improved pain interference, anxiety, positive affect, and catastrophizing (p’s ≀ .05). Conclusion Informal home practice quantity, but not formal practice quantity, is associated with improved outcomes during an abbreviated MBI for chronic pain. For these MBIs, it is important to evaluate the distinct roles of formal and informal practice.ClinicalTrials.gov RegistrationNCT03495856

    Impact of the COVID ‐19 pandemic on patients with hidradenitis suppurativa

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    The COVID-19 pandemic caused collateral damage to patients with acute and chronic conditions. In this mono-centre cross-sectional study, we sought to evaluate the impact of the COVID-19 pandemic on patients with hidradenitis suppurativa (HS). In June 2020, we sent an anonymous survey to 109 patients, who were diagnosed with HS in our outpatient clinic from May 2018 to April 2020. Fifty patients (45.9%) completed and returned the survey. Forty-five participants (90.0%) denied any cancellation of hospitalisation due to the COVID-19 pandemic. Hospitalisation was postponed in 8% of cases and cancelled in 2%. Compared to prior to the pandemic, fewer patients consulted their primary physician for changing wound dressings and more changed the dressings themselves or were assisted by their family members. 13% of patients avoided doctor visits due to fear of COVID-19 and 26.1% minimised doctor visits. The Dermatology Life Quality Index showed a moderate to very severe impact on patients' Quality of Life (mean score = 10.06). Only one patient used telemedicine. Due to limited access to primary care and fear of COVID-19, the pandemic had a detectable impact on the hospital management of patients with HS in our facility. Telemedicine still plays a negligible role in primary wound care
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