578 research outputs found

    Pluricomplex Green and Lempert functions for equally weighted poles

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    For Ω\Omega a domain in Cn\mathbb C^n, the pluricomplex Green function with poles a1,...,aNΩa_1, ...,a_N \in \Omega is defined as G(z):=sup{u(z):uPSH(Ω),u(x)logxaj+Cjwhenxaj,j=1,...,N}G(z):=\sup \{u(z): u\in PSH_-(\Omega), u(x)\le \log \|x-a_j\|+C_j \text{when} x \to a_j, j=1,...,N \}. When there is only one pole, or two poles in the unit ball, it turns out to be equal to the Lempert function defined from analytic disks into Ω\Omega by LS(z):=inf{j=1Nνjlogζj:ϕO(D,Ω),ϕ(0)=z,ϕ(ζj)=aj,j=1,...,N}L_S (z) :=\inf \{\sum^N_{j=1}\nu_j\log|\zeta_j|: \exists \phi\in \mathcal {O}(\mathbb D,\Omega), \phi(0)=z, \phi(\zeta_j)=a_j, j=1,...,N \}. It is known that we always have LS(z)GS(z)L_S (z) \ge G_S(z). In the more general case where we allow weighted poles, there is a counterexample to equality due to Carlehed and Wiegerinck, with Ω\Omega equal to the bidisk. Here we exhibit a counterexample using only four distinct equally weighted poles in the bidisk. In order to do so, we first define a more general notion of Lempert function "with multiplicities", analogous to the generalized Green functions of Lelong and Rashkovskii, then we show how in some examples this can be realized as a limit of regular Lempert functions when the poles tend to each other. Finally, from an example where LS(z)>GS(z)L_S (z) > G_S(z) in the case of multiple poles, we deduce that distinct (but close enough) equally weighted poles will provide an example of the same inequality. Open questions are pointed out about the limits of Green and Lempert functions when poles tend to each other.Comment: 25 page

    Development and validation of two self-reported tools for insulin resistance and hypertension risk assessment in a European cohort : the Feel4Diabetes-study

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    Early identification of type 2 diabetes mellitus (T2DM) and hypertension (HTN) risk may improve prevention and promote public health. Implementation of self-reported scores for risk assessment provides an alternative cost-effective tool. The study aimed to develop and validate two easy-to-apply screening tools identifying high-risk individuals for insulin resistance (IR) and HTN in a European cohort. Sociodemographic, lifestyle, anthropometric and clinical data obtained from 1581 and 1350 adults (baseline data from the Feel4Diabetes-study) were used for the European IR and the European HTN risk assessment index respectively. Body mass index, waist circumference, sex, age, breakfast consumption, alcohol, legumes and sugary drinks intake, physical activity and sedentary behavior were significantly correlated with Homeostatic Model Assessment of IR (HOMA-IR) and/or HTN and incorporated in the two models. For the IR index, the Area Under the Curve (AUC), sensitivity and specificity for identifying individuals above the 75th and 95th of HOMA-IR percentiles were 0.768 (95%CI: 0.721–0.815), 0.720 and 0.691 and 0.828 (95%CI: 0.766–0.890), 0.696 and 0.778 respectively. For the HTN index, the AUC, sensitivity and specificity were 0.778 (95%CI: 0.680–0.876), 0.667 and 0.797. The developed risk assessment tools are easy-to-apply, valid, and low-cost, identifying European adults at high risk for developing T2DM or having HTN

    Effectiveness of a family-, school- and community-based intervention on physical activity and its correlates in Belgian families with an increased risk for type 2 diabetes mellitus: the Feel4Diabetes-study

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    BACKGROUND: The study aimed to investigate the effectiveness of the European Feel4Diabetes intervention, promoting a healthy lifestyle, on physical activity and its correlates among families at risk for type 2 diabetes mellitus (based on the Finnish Diabetes Risk Score) in Belgium. METHODS: The Feel4Diabetes intervention involved three components: family, school and community component, with the family component consisting of 6 counseling sessions for families at risk. Main outcomes were objectively measured physical activity levels and its subjectively measured correlates. The final sample consisted of 454 parents (mean age 39.4¿years; 72.0% women) and 444 children (mean age 8.0¿years; 50.1% girls). Multilevel repeated measures analyses were performed to assess intervention effectiveness after 1 year. RESULTS: In parents, there was no significant intervention effect. In children, there were only significant negative effects for moderate to vigorous physical activity (p¿=¿0.05; ¿p2¿=¿0.008) and steps (p¿=¿0.03; ¿p2¿=¿0.006%) on weekdays, with physical activity decreasing (more) in the intervention group. CONCLUSIONS: The F4D-intervention lacks effectiveness on high-risk families'' physical activity and its correlates in Belgium. This could partially be explained by low attendance rates and a large drop-out. To reach vulnerable populations, future interventions should invest in more appropriate recruitment (e.g. more face-to-face contact) and more bottom-up development of the intervention (i.e. co-creation of the intervention with the target group)

    The effect of a cluster-randomized controlled trial on lifestyle behaviors among families at risk for developing type 2 diabetes across Europe: the Feel4Diabetes-study

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    Background: This study investigated the effect of the Feel4Diabetes-intervention, a 2-year multilevel intervention, on energy balance-related behaviors among European families at risk for developing type 2 diabetes. Intervention effects on self-reported physical activity, sedentary behavior and eating behaviors were investigated across and within the participating countries: Belgium, Finland, Greece, Spain, Hungary and Bulgaria. Methods: Families were recruited through schools, located in low socio-economic status areas. In total, 4484 families at risk for developing type 2 diabetes were selected using the FINDRISC-questionnaire. Parents’ and children’s energy balance-related behaviors data were collected by questionnaires at three time points (baseline, mid- and post intervention). Families assigned to the intervention group were invited to participate in a 2-year school-, community-, and family-based intervention to promote a healthier lifestyle, including counseling sessions (first intervention year) and text messages (second intervention year). Families assigned to the control group received standard care, including medical check-up results and recommendations and tips regarding a healthy lifestyle. To assess the intervention-effects, Mixed Models were conducted using the R-Package “lmer “with R v3.2. Results: Significant intervention effects were found on a certain number of families’ lifestyle behaviors. Significant favorable intervention effects were detected on parents’ water consumption and consumption of fruit and vegetables, and on children’s consumption of sweets and moderate-to-vigorous physical activity. Analyses by country revealed significant favorable intervention effects on water consumption and on moderate-to-vigorous physical activity in Belgian parents and on fruit and vegetable consumption among Belgian children, on sweets consumption among Spanish parents and children, and on moderate-to-vigorous physical activity among Finnish children. Unfavorable intervention effects were found on the consumption of soft drinks and sugar-containing juices among Hungarian children and parents, while when examining the intervention effects for the overall population and per country, 10 from the 112 investigated outcome variables were improved in the intervention group compared to the control group (9%). Conclusions: The Feel4Diabetes-intervention managed to improve a certain number of targeted lifestyle behaviors while the intervention was not effective on a large number of targeted lifestyle behaviors. The findings of the current study are encouraging, but further research is needed on how we can further improve effectiveness of lifestyle interventions to prevent type 2 diabetes in families at risk. Trial registration: The Feel4Diabetes-study is registered with the clinical trials registry http://clinicaltrials.gov, ID: 643708. © 2021, The Author(s)

    Methodology of the health economic evaluation of the Feel4Diabetes-study

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    Background: The clinical and economic burden of type 2 diabetes mellitus on society is rising. Effective and efficient preventive measures may stop the increasing prevalence, given that type 2 diabetes mellitus is mainly a lifestyle-driven disease. The Feel4Diabetes-study aimed to tackle unhealthy lifestyle (unhealthy diet, lack of physical activity, sedentary behaviour, and excess weight) of families with a child in the first grades of elementary school. These schools were located in regions with a relatively low socio-economic status in Belgium, Bulgaria, Finland, Greece, Hungary and Spain. Special attention was paid to families with a high risk of developing type 2 diabetes mellitus. Methods: The aim of this paper is to describe the detailed methodology of the intervention’s cost-effectiveness analysis. Based on the health economic evaluation of the Toybox-study, both a decision analytic part and a Markov model have been designed to assess the long-term (time horizon of 70 year with one-year cycles) intervention’s value for money. Data sources used for the calculation of health state incidences, transition probabilities between health states, health state costs, and health state utilities are listed. Intervention-related costs were collected by questionnaires and diaries, and attributed to either all families or high risk families only. Conclusions: The optimal use of limited resources is pivotal. The future results of the health economic evaluation of the Feel4Diabetes-study will contribute to the efficient use of those resources.Publication of this supplement was funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement n° 643708

    Lipidemic profile changes over a two-year intervention period : who benefited most from the Feel4Diabetes program?

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    Identification of participants' characteristics who benefited most from large community-based intervention studies may guide future prevention initiatives in order to maximize their effectiveness. The current study aimed to examine the socio-demographic, anthropometric, and behavioral characteristics, as well as the health and eating perceptions of those who improved their lipidemic profile, in the Feel4Diabetes early screening and prevention program. In the present analyses, 1773 adults from families at high risk for developing type 2 diabetes mellitus (T2DM) were enrolled, receiving either the standard care or the more intensive intervention, and 33.3-55.2% of them improved one or more of their lipidemic indices by >5%. Women, people living in Southeastern Europe, coming from two-parent families, having higher financial security, educational level and better diet quality were associated with a 27-64% higher likelihood for benefiting from the program regarding one or more of their lipidemic profile indices. Participants who were overweight or obese (especially with central obesity), employed, with prolonged sedentary behavior, prone to emotional eating and perceiving their weight status as lower than their actual weight were 24-43% less likely to have benefited. These findings should guide future interventions, prioritizing regions in greater need, and being tailor-made to specific population characteristics in order to further improve their effectiveness

    Common carotid intima media thickness and ankle-brachial pressure index correlate with local but not global atheroma burden:a cross sectional study using whole body magnetic resonance angiography

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    Common carotid intima media thickness (CIMT) and ankle brachial pressure index (ABPI) are used as surrogate marker of atherosclerosis, and have been shown to correlate with arterial stiffness, however their correlation with global atherosclerotic burden has not been previously assessed. We compare CIMT and ABPI with atheroma burden as measured by whole body magnetic resonance angiography (WB-MRA).50 patients with symptomatic peripheral arterial disease were recruited. CIMT was measured using ultrasound while rest and exercise ABPI were performed. WB-MRA was performed in a 1.5T MRI scanner using 4 volume acquisitions with a divided dose of intravenous gadolinium gadoterate meglumine (Dotarem, Guerbet, FR). The WB-MRA data was divided into 31 anatomical arterial segments with each scored according to degree of luminal narrowing: 0 = normal, 1 = <50%, 2 = 50-70%, 3 = 70-99%, 4 = vessel occlusion. The segment scores were summed and from this a standardized atheroma score was calculated.The atherosclerotic burden was high with a standardised atheroma score of 39.5±11. Common CIMT showed a positive correlation with the whole body atheroma score (β 0.32, p = 0.045), however this was due to its strong correlation with the neck and thoracic segments (β 0.42 p = 0.01) with no correlation with the rest of the body. ABPI correlated with the whole body atheroma score (β -0.39, p = 0.012), which was due to a strong correlation with the ilio-femoral vessels with no correlation with the thoracic or neck vessels. On multiple linear regression, no correlation between CIMT and global atheroma burden was present (β 0.13 p = 0.45), while the correlation between ABPI and atheroma burden persisted (β -0.45 p = 0.005).ABPI but not CIMT correlates with global atheroma burden as measured by whole body contrast enhanced magnetic resonance angiography in a population with symptomatic peripheral arterial disease. However this is primarily due to a strong correlation with ilio-femoral atheroma burden

    Between-group behaviour in health care: gaps, edges, boundaries, disconnections, weak ties, spaces and holes. A systematic review

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    <p>Abstract</p> <p>Background</p> <p>Gaps are typically regarded as a problem to be solved. People are stimulated to close or plug them. Researchers are moved to fill deficits in the literature in order to realise a more complete knowledge base, health authorities want to bridge policy-practice disconnections, managers to secure resources to remedy shortfalls between poor and idealised care, and clinicians to provide services to patients across the divides of organisational silos.</p> <p>Despite practical and policy work in many health systems to bridge gaps, it is valuable to study research examining them for the insights provided. Structural holes, spaces between social clusters and weak or absent ties represent fissures in networks, located in less densely populated parts of otherwise closely connected social structures. Such gaps are useful as they illustrate how communication potentially breaks down or interactivity fails. This paper discusses empirical and theoretical work on this phenomenon with the aim of analysing a specific exemplar, the structures of silos within health care organisations.</p> <p>Methods</p> <p>The research literature on social spaces, holes, gaps, boundaries and edges was searched systematically, and separated into health [n = 13] and non-health [n = 55] samples. The health literature was reviewed and synthesised in order to understand the circumstances between stakeholders and stakeholder groups that both provide threats to networked interactions and opportunities to strengthen the fabric of organisational and institutional inter-relationships.</p> <p>Results</p> <p>The research examples illuminate various network structure characteristics and group interactions. They explicate a range of opportunities for improved social and professional relations that understanding structural holes, social spaces and absent ties affords. A principal finding is that these kinds of gaps illustrate the conditions under which connections are strained or have been severed, where the limits of integration between groups occurs, the circumstances in which social spaces are or need to be negotiated and the way divides are bridged. The study's limitations are that it is bounded by the focus of attention and the search terms used and there is yet to be developed a probabilistic, predictive model for gaps and how to connect them.</p> <p>Conclusions</p> <p>Gaps offer insights into social structures, and how real world behaviours of participants in workplaces, organisations and institutions are fragile. The paper highlights the circumstances in which network disjunctures and group divides manifest. Knowledge of these phenomenon provides opportunities for working out ways to improve health sector organisational communications, knowledge transmission and relationships.</p

    Study of polytopic membrane protein topological organization as a function of membrane lipid composition.

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    A protocol is described using lipid mutants and thiol-specific chemical reagents to study lipid-dependent and host-specific membrane protein topogenesis by the substituted-cysteine accessibility method as applied to transmembrane domains (SCAM). SCAM is adapted to follow changes in membrane protein topology as a function of changes in membrane lipid composition. The strategy described can be adapted to any membrane system
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