255 research outputs found

    Branched Microstructures in the Ginzburg-Landau Model of Type-I Superconductors

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    We consider the Ginzburg-Landau energy for a type-I superconductor in the shape of an infinite three-dimensional slab, with two-dimensional periodicity, with an applied magnetic field which is uniform and perpendicular to the slab. We determine the optimal scaling law of the minimal energy in terms of the parameters of the problem, when the applied magnetic field is sufficiently small and the sample sufficiently thick. This optimal scaling law is proven via ansatz-free lower bounds and an explicit branching construction which refines further and further as one approaches the surface of the sample. Two different regimes appear, with different scaling exponents. In the first regime, the branching leads to an almost uniform magnetic field pattern on the boundary; in the second one the inhomogeneity survives up to the boundary.Comment: 42 pages, 5 figure

    A branched transport limit of the Ginzburg-Landau functional

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    We study the Ginzburg-Landau model of type-I superconductors in the regime of small external magnetic fields. We show that, in an appropriate asymptotic regime, flux patterns are described by a simplified branched transportation functional. We derive the simplified functional from the full Ginzburg-Landau model rigorously via Γ\Gamma-convergence. The detailed analysis of the limiting procedure and the study of the limiting functional lead to a precise understanding of the multiple scales contained in the model

    Heterozygosity Probabilities for Normal Relatives of Isolated Cases Affected by Incompletely Penetrant Conditions and the Calculation of Recurrence Risks for Their Offspring. I. Autosomal Dominant Genes

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    Heterozygosity probabilities P(het) for relatives of isolated cases produced by incompletely penetrant autosomal dominant genes and recurrence risks for their offspring, R = P(het).K/2, where K is the penetrance value, have been calculated in the literature for some simple particular situations. Bayes theorem and elements from the theory of finite difference equations enabled us to derive the heterozygosity probability for any individual belonging to a pedigree containing an isolated case affected with an incompletely penetrant autosomal dominant disorder. The generalized formula here derived is valid for most particular cases thus far studied in the literature. Am. J. Med. Genet. 95:43-48, 2000

    The Soil as a Bioreactor: Reaction-Diffusion Processes and Biofilms

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    Abstract: The fate of organic substances in soil strongly depends on biological processes. These biological processes are shaped by microorganisms, which occur in soil pores, either in suspension or as biofilms inside and outside soil aggregates. Biofilms alter the pore geometry while growing which directly influences the soil water flow field and hence the convective transport of organic substances. In this paper we present a model of the bioreactor soil at the pore scale under saturated conditions comprising coupled fluid flow, transport, reaction, sorption, and biofilm dynamics. The spatio-temporal development of the biofilm is altering properties such as viscosity, diffusion coefficient and degradation rates. The degradation potential of organic substances was analyzed by considering the influence of microbes on their breakthrough behavior. The model results underline that biological processes exert a major influence on the fate of organic substances in soil

    Time course of vascular response after an a priori strategy of bare metal stent implantation post-dilated with a paclitaxel-coated balloon: Implementation of a three-dimensional analysis algorithm with optical coherence tomography

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    Background: An a priori combined therapy of a bare metal stent post-dilated with a paclitaxel- -coated balloon (PCB) was investigated with optical coherence tomography (OCT) at 2 and 6 months regarding vessel response. Previous studies have shown inconsistent results and the time course of vessel healing after such an interventional strategy is unknown. Methods: Thirty-three de novo lesions in 32 patients were electively treated. Six-month OCT analysis was available in 24 lesions. Two-month OCT follow-up was obtained in 16 lesions. Sequential OCT at 2 and 6 months was available in 7 patients. A novel 3-dimensional picture of vessel segments as spread outs was implemented. Results: Severe incomplete stent apposition (ISA) accompanied by significantly lower strut coverage were found at 2-month compared with 6-month follow-up (ISA struts: 11.4 ± 11.8% vs. 1.8 ± 4.8%, p = 0.001; uncovered struts: 14.5 ± 14.8% vs. 2.0 ± 5.3%, p = 0.001). ISA size diminished over time and the possibly observed phenomenon of positive vessel remodeling (remodeling volume: 4.9 ± 5.9 mm3 at 2-months vs. 2.0 ± 2.6 mm3 at 6-months; p = 0.042) was largely reversible in most lesions. Conclusions: Bare metal stenting with adjunctive application of paclitaxel by a coated bal­loon shows transient severe incomplete strut apposition, most likely due to focal positive ves­sel remodeling. Thus, caution is needed in bailout situations following a PCB angioplasty. A novel illustration of OCT parameters as “carpet views” enables a comprehensive analysis of investigated stents.

    Human knee joint finite element model using a two bundle anterior cruciate ligament: Validation and gait analysis

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    Anterior cruciate ligament (ACL) deficient individuals are at a much higher risk of developing osteoarthritis (OA) compared to those with intact ACLs, likely due to altered biomechanical loading [1]. Research indicates the ACL is comprised of two “bundles”, the anteromedial (AM) and posterolateral (PL) bundles [2]. Although the function of both bundles is to restrain anterior tibial translation (ATT), each bundle has their own distinct range of knee flexion where they are most effective [3]. Articular cartilage contact stress measurements are difficult to measure in vivo. An alternative approach is to use knee joint finite element models (FEMs) to predict soft tissue stresses and strains throughout the knee. Initial and boundary conditions for these FEMs may be determined from knee joint kinematics estimated from motion analysis experiments. However, there is a lack of knee joint FEMs which include both AM and PL bundles to predict changes to articular cartilage contact pressures resulting from ACL injuries. The purpose of this study is to develop and validate a knee joint FEM using both AM and PL bundles and subsequently perform a gait analysis of varying ACL injuries

    The impact of tricuspid annular geometry on outcome after percutaneous edge-to-edge repair for severe tricuspid regurgitation

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    Background: Percutaneous tricuspid repair using the edge-to-edge technique is a novel treatment option. More data are needed to better understand which aspects predict a favorable outcome. Methods: Twenty high-risk patients (78.6 ± 8.3 years, EuroScore II 9.1 ± 7.7%, STS score 8.8 ± 4.3) with severe symptomatic tricuspid regurgitation (TR) were treated with the MitraClip® system. All patients underwent standardized pre-, peri-, and post-procedural evaluation. Acute success was defined as successful edge-to-edge repair with TR reduction of ≥ 1 grade and survival until hospital discharge.Results: Fifteen (75%) patients showed acute success until discharge and 12 (60%) at 30-day followup. In 5 (25%) patients repair failed due to either unsuccessful clip implantation (n = 2), single leaflet device attachment (n = 1), TR reduction < 1 grade (n = 1), or in-hospital death (n = 1). Comparing patients with successful procedure versus those with failed repair revealed similar comorbidities but more severe right heart failure, lower left ventricular ejection fraction, worse renal function, and higher diuretic equivalent doses in the failed repair group. No differences in conventional echocardiographic parameters for TR severity but more dilated tricuspid annulus geometry (tricuspid valve annulus, coaptation depth, tenting area) in the failed repair group were observed. The success rate of non-central/non-anteroseptal jet location was only 25%.Conclusions: Tricuspid annulus geometry assessment may be of crucial importance and seems to impact procedural outcomes in patients undergoing edge-to-edge tricuspid valve repair. Further investigations including advanced imaging are needed to better understand and treat this complex valve disease

    The Planetary Health Academy—a virtual lecture series for transformative education in Germany

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    The planetary crises require health professionals to understand the interlinkages between health and environmental changes, and how to reduce ecological harm (ie, ecological footprint) and promote positive change (ie, ecological handprint). However, health professions’ education and training are mostly lacking these aspects. In this Viewpoint, we report findings from the evaluation of the Planetary Health Academy, the first open online lecture series for transformative planetary health education in Germany. In a retrospective online survey, 458 of 3656 Planetary Health Academy participants reported on their emotions towards climate change, attitudes towards health professionals’ responsibilities, self-efficacy, and the contribution of the Planetary Health Academy to their knowledge and actions. Additionally, motivators and barriers to acting were assessed. Our findings provide insights that can inform future efforts for transformative education. Combined with network and movement building, education could act as a social tipping element toward actions to mitigate global environmental changes

    The LEAD (Lung, Heart, Social, Body) Study: Objectives, Methodology, and External Validity of the Population-Based Cohort Study

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    BACKGROUND: The Lung, hEart, sociAl, boDy (LEAD) Study (ClinicalTrials.gov; NCT01727518; http://clinicaltrials.gov) is a longitudinal, observational, population-based Austrian cohort that aims to investigate the relationship between genetic, environmental, social, developmental and ageing factors influencing respiratory health and comorbidities through life. The general working hypothesis of LEAD is the interaction of these genetic, environmental and socioeconomic factors influences lung development and ageing, the risk of occurrence of several non-communicable diseases (respiratory, cardiovascular, metabolic and neurologic), as well as their phenotypic (ie, clinical) presentation. METHODS: LEAD invited from 2011-2016 a random sample (stratified by age, gender, residential area) of Vienna inhabitants (urban cohort) and all the inhabitants of six villages from Lower Austria (rural cohort). Participants will be followed-up every four years. A number of investigations and measurements were obtained in each of the four domains of the study (Lung, hEart, sociAl, boDy) including data to screen for lung, cardiovascular and metabolic diseases, osteoporosis, and cognitive function. Blood and urine samples are stored in a biobank for future investigations. RESULTS: A total of 11.423 males (47.6%) and females (52.4%), aged 6-80 years have been included in the cohort. Compared to governmental statistics, the external validity of LEAD with respect to age, gender, citizenship, and smoking status was high. CONCLUSIONS: In conclusion, the LEAD cohort has been established following high quality standards; it is representative of the Austrian population and offers a platform to understand lung development and ageing as a key mechanism of human health both in early and late adulthood
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