| 1. |
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| 2. |
- Aamer, Aysha, et al.
(author)
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A precursor plateau and pre-maximum [O ii] emission in the superluminous SN2019szu : a pulsational pair-instability candidate
- 2023
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In: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 527:4, s. 11970-11995
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Journal article (peer-reviewed)abstract
- We present a detailed study on SN2019szu, a Type I superluminous supernova at z = 0.213 that displayed unique photometric and spectroscopic properties. Pan-STARRS and ZTF forced photometry show a pre-explosion plateau lasting ∼40 d. Unlike other SLSNe that show decreasing photospheric temperatures with time, the optical colours show an apparent temperature increase from ∼15 000 to ∼20 000 K over the first 70 d, likely caused by an additional pseudo-continuum in the spectrum. Remarkably, the spectrum displays a forbidden emission line (likely attributed to λλ7320,7330) visible 16 d before maximum light, inconsistent with an apparently compact photosphere. This identification is further strengthened by the appearances of [O III] λλ4959, 5007, and [O III] λ4363 seen in the spectrum. Comparing with nebular spectral models, we find that the oxygen line fluxes and ratios can be reproduced with ∼0.25 M⊙ of oxygen-rich material with a density of ∼10−15 g cm−3. The low density suggests a circumstellar origin, but the early onset of the emission lines requires that this material was ejected within the final months before the terminal explosion, consistent with the timing of the precursor plateau. Interaction with denser material closer to the explosion likely produced the pseudo-continuum bluewards of ∼5500 Å. We suggest that this event is one of the best candidates to date for a pulsational pair-instability ejection, with early pulses providing the low density material needed for the formation of the forbidden emission line, and collisions between the final shells of ejected material producing the pre-explosion plateau.
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| 3. |
- Akenine, Ulrika, et al.
(author)
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Attitudes of at-risk older adults about prevention of cardiovascular disease and dementia using eHealth : a qualitative study in a European context
- 2020
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In: BMJ Open. - 2044-6055. ; 10:8
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Journal article (peer-reviewed)abstract
- Objectives Prevention of cardiovascular disease (CVD) and dementia is a key health priority among older adults. Understanding individuals’ attitudes to, the prevention of these conditions, particularly when delivered through novel eHealth tools, could help in designing effective prevention programmes. The aim of the study was to explore the attitudes of older adults at increased risk of CVD and dementia regarding engagement in eHealth self-management prevention programmes, and to describe the facilitators and barriers.Design A qualitative research approach was used. Data were collected through eight focus groups in Finland, France and the Netherlands. Data were analysed following the principles of grounded theory.Setting and participants Forty-four community-dwellers aged 65+ at risk of CVD were recruited from a previous trial cohort in Finland, and through general practices in France and the Netherlands.Results The study identified three categories: access to reliable information, trust in the healthcare providers and burden and stigma of dementia. A core category was also identified: the interactive process of the three categories influencing engagement in self-management prevention programme. The categories were interconnected through an interactive process and influenced by the local healthcare culture and context which shaped them differently, becoming either facilitators or barriers to engage in eHealth self-management prevention programmes.Conclusions The study emphasises the importance of considering the interactions between the identified categories in this study, grounded in the local healthcare culture and context in further developments of eHealth self-management interventions that aim to prevent CVD and dementia.
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| 4. |
- Barbera, Mariagnese, et al.
(author)
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Designing an Internet-Based Multidomain Intervention for the Prevention of Cardiovascular Disease and Cognitive Impairment in Older Adults : The HATICE Trial
- 2018
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In: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 62:2, s. 649-663
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Journal article (peer-reviewed)abstract
- Background: Many dementia and cardiovascular disease (CVD) cases in older adults are attributable to modifiable vascular and lifestyle-related risk factors, providing opportunities for prevention. In the Healthy Aging Through Internet Counselling in the Elderly (HATICE) randomized controlled trial, an internet-based multidomain intervention is being tested to improve the cardiovascular risk (CVR) profile of older adults. Objective: To design a multidomain intervention to improve CVR, based on the guidelines for CVR management, and administered through a coach-supported, interactive, platform to over 2500 community-dwellers aged 65+ in three European countries. Methods: A comparative analysis of national and European guidelines for primary and secondary CVD prevention was performed. Results were used to define the content of the intervention. Results: The intervention design focused on promoting awareness and self-management of hypertension, dyslipidemia, diabetes mellitus, and overweight, and supporting smoking cessation, physical activity, and healthy diet. Overall, available guidelines lacked specific recommendations for CVR management in older adults. The comparative analysis of the guidelines showed general consistency for lifestyle-related recommendations. Key differences, identified mostly in methods used to assess the overall CVR, did not hamper the intervention design. Minor country-specific adaptations were implemented to maximize the intervention feasibility in each country. Conclusion: Despite differences inCVRmanagement within the countries considered, itwas possible to design and implement the HATICE multidomain intervention. The study can help define preventative strategies for dementia and CVD that are applicable internationally.
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| 5. |
- Beishuizen, Cathrien R. L., et al.
(author)
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Web-Based Interventions Targeting Cardiovascular Risk Factors in Middle-Aged and Older People : A Systematic Review and Meta-Analysis
- 2016
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In: Journal of Medical Internet Research. - : JMIR Publications Inc.. - 1438-8871. ; 18:3
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Research review (peer-reviewed)abstract
- Background: Web-based interventions can improve single cardiovascular risk factors in adult populations. In view of global aging and the associated increasing burden of cardiovascular disease, older people form an important target population as well.Objective: In this systematic review and meta-analysis, we evaluated whether Web-based interventions for cardiovascular risk factor management reduce the risk of cardiovascular disease in older people.Methods: Embase, Medline, Cochrane and CINAHL were systematically searched from January 1995 to November 2014. Search terms included cardiovascular risk factors and diseases (specified), Web-based interventions (and synonyms) and randomized controlled trial. Two authors independently performed study selection, data-extraction and risk of bias assessment. In a meta-analysis, outcomes regarding treatment effects on cardiovascular risk factors (blood pressure, glycated hemoglobin A1c (HbA1C), low-density lipoprotein (LDL) cholesterol, smoking status, weight and physical inactivity) and incident cardiovascular disease were pooled with random effects models.Results: A total of 57 studies (N=19,862) fulfilled eligibility criteria and 47 studies contributed to the meta-analysis. A significant reduction in systolic blood pressure (mean difference -2.66 mmHg, 95% CI -3.81 to -1.52), diastolic blood pressure (mean difference -1.26 mmHg, 95% CI -1.92 to -0.60), HbA1c level (mean difference -0.13%, 95% CI -0.22 to -0.05), LDL cholesterol level (mean difference -2.18 mg/dL, 95% CI -3.96 to -0.41), weight (mean difference -1.34 kg, 95% CI -1.91 to -0.77), and an increase of physical activity (standardized mean difference 0.25, 95% CI 0.10-0.39) in the Web-based intervention group was found. The observed effects were more pronounced in studies with short (<12 months) follow-up and studies that combined the Internet application with human support (blended care). No difference in incident cardiovascular disease was found between groups (6 studies).Conclusions: Web-based interventions have the potential to improve the cardiovascular risk profile of older people, but the effects are modest and decline with time. Currently, there is insufficient evidence for an effect on incident cardiovascular disease. A focus on long-term effects, clinical endpoints, and strategies to increase sustainability of treatment effects is recommended for future studies.
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| 6. |
- Hoevenaar-Blom, Marieke P., et al.
(author)
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Improving data sharing in research with context-free encoded missing data
- 2017
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:9
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Journal article (peer-reviewed)abstract
- Lack of attention to missing data in research may result in biased results, loss of power and reduced generalizability. Registering reasons for missing values at the time of data collection, or-in the case of sharing existing data-before making data available to other teams, can save time and efforts, improve scientific value and help to prevent erroneous assumptions and biased results. To ensure that encoding of missing data is sufficient to understand the reason why data are missing, it should ideally be context-free. Therefore, 11 context-free codes of missing data were carefully designed based on three completed randomized controlled clinical trials and tested in a new randomized controlled clinical trial by an international team consisting of clinical researchers and epidemiologists with extended experience in designing and conducting trials and an Information System expert. These codes can be divided into missing due to participant and/or participation characteristics (n = 6), missing by design (n = 4), and due to a procedural error (n = 1). Broad implementation of context-free missing data encoding may enhance the possibilities of data sharing and pooling, thus allowing more powerful analyses using existing data.
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| 7. |
- Hosseinzadeh, Griffin, et al.
(author)
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Photometric Classification of 2315 Pan-STARRS1 Supernovae with Superphot
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 905:2
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Journal article (peer-reviewed)abstract
- The classification of supernovae (SNe) and its impact on our understanding of explosion physics and progenitors have traditionally been based on the presence or absence of certain spectral features. However, current and upcoming wide-field time-domain surveys have increased the transient discovery rate far beyond our capacity to obtain even a single spectrum of each new event. We must therefore rely heavily on photometric classification-connecting SN light curves back to their spectroscopically defined classes. Here, we present Superphot, an open-source Python implementation of the machine-learning classification algorithm of Villar et al., and apply it to 2315 previously unclassified transients from the Pan-STARRS1 Medium Deep Survey for which we obtained spectroscopic host-galaxy redshifts. Our classifier achieves an overall accuracy of 82%, with completenesses and purities of >80% for the best classes (SNe Ia and superluminous SNe). For the worst performing SN class (SNe Ibc), the completeness and purity fall to 37% and 21%, respectively. Our classifier provides 1257 newly classified SNe Ia, 521 SNe II, 298 SNe Ibc, 181 SNe IIn, and 58 SLSNe. These are among the largest uniformly observed samples of SNe available in the literature and will enable a wide range of statistical studies of each class.
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| 8. |
- Jongstra, Susan, et al.
(author)
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Development and Validation of an Interactive Internet Platform for Older People : The Healthy Ageing Through Internet Counselling in the Elderly Study
- 2017
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In: Telemedicine journal and e-health. - : Mary Ann Liebert Inc. - 1530-5627 .- 1556-3669. ; 23:2, s. 96-104
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Journal article (peer-reviewed)abstract
- Background: A myriad of Web-based applications on self-management have been developed, but few focus on older people. In the face of global aging, older people form an important target population for cardiovascular prevention. This article describes the full development of an interactive Internet platform for older people, which was designed for the Healthy Ageing Through Internet Counselling in the Elderly (HATICE) study. We provide recommendations to design senior-friendly Web-based applications for a new approach to multicomponent cardiovascular prevention. Methods: The development of the platform followed five phases: (1) conceptual framework; (2) platform concept and functional design; (3) platform building (software and content); (4) testing and pilot study; and (5) final product. Results: We performed a meta-analysis, reviewed guidelines for cardiovascular diseases, and consulted end users, experts, and software devel-opers to create the platform concept and content. The software was built in iterative cycles. In the pilot study, 41 people aged >= 65 years used the platform for 8 weeks. Participants used the interactive features of the platform and appreciated the coach support. During all phases adjustments were made to incorporate all improvements from the previous phases. The final platform is a personal, secured, and interactive platform supported by a coach. Discussion: When carefully designed, an interactive Internet platform is acceptable and feasible for use by older people with basic computer skills. To improve acceptability by older people, we recommend involving the end users in the process of development, to personalize the platform and to combine the application with human support. The interactive HATICE platform will be tested for efficacy in a multinational randomized controlled trial (ISRCTN48151589).
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| 9. |
- Katebi, Reza, et al.
(author)
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PS1-13cbe : the rapid transition of a Seyfert 2 to a Seyfert 1
- 2019
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 487:3, s. 4057-4070
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Journal article (peer-reviewed)abstract
- We present a nuclear transient event, PS1-13cbe, that was first discovered in the Pan-STARRS1 survey in 2013. The outburst occurred in the nucleus of the galaxy SDSS J222153.87+003054.2 at z = 0.123 55, which was classified as a Seyfert 2 in a pre-outburst archival Sloan Digital Sky Survey (SDSS) spectrum. PS1-13cbe showed the appearance of strong broad H alpha and H beta emission lines and a non-stellar continuum in a Magellan spectrum taken 57 d after the peak of the outburst that resembled the characteristics of a Seyfert 1. These broad lines were not present in the SDSS spectrum taken a decade earlier and faded away within 2 yr, as observed in several late-time MDM spectra. We argue that the dramatic appearance and disappearance of the broad lines and a factor of similar to 8 increase in the optical continuum are most likely caused by variability in the pre-existing accretion disc than a tidal disruption event, supernova, or variable obscuration. The time-scale for the turn-on of the optical emission of similar to 70 d observed in this transient is among the shortest observed in a 'changing-look' active galactic nucleus,
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| 10. |
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| 11. |
- Norrving, Bo, et al.
(author)
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Action Plan for Stroke in Europe 2018–2030
- 2018
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In: European Stroke Journal. - : SAGE Publications. - 2396-9873 .- 2396-9881. ; 3:4, s. 309-336
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Journal article (peer-reviewed)abstract
- Two previous pan-European consensus meetings, the 1995 and 2006 Helsingborg meetings, were convened to review the scientific evidence and the state of current services to identify priorities for research and development and to set targets for the development of stroke care for the decade to follow. Adhering to the same format, the European Stroke Organisation (ESO) prepared a European Stroke Action Plan (ESAP) for the years 2018 to 2030, in cooperation with the Stroke Alliance for Europe (SAFE). The ESAP included seven domains: primary prevention, organisation of stroke services, management of acute stroke, secondary prevention, rehabilitation, evaluation of stroke outcome and quality assessment and life after stroke. Research priorities for translational stroke research were also identified. Documents were prepared by a working group and were open to public comments. The final document was prepared after a workshop in Munich on 21–23 March 2018. Four overarching targets for 2030 were identified: (1) to reduce the absolute number of strokes in Europe by 10%, (2) to treat 90% or more of all patients with stroke in Europe in a dedicated stroke unit as the first level of care, (3) to have national plans for stroke encompassing the entire chain of care, (4) to fully implement national strategies for multisector public health interventions. Overall, 30 targets and 72 research priorities were identified for the seven domains. The ESAP provides a basic road map and sets targets for the implementation of evidence-based preventive actions and stroke services to 2030.
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| 12. |
- Peters, Ruth, et al.
(author)
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An investigation of antihypertensive class, dementia, and cognitive decline: A meta-analysis.
- 2020
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In: Neurology. - 1526-632X. ; 94:3
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Journal article (peer-reviewed)abstract
- High blood pressure is one of the main modifiable risk factors for dementia. However, there is conflicting evidence regarding the best antihypertensive class for optimizing cognition. Our objective was to determine whether any particular antihypertensive class was associated with a reduced risk of cognitive decline or dementia using comprehensive meta-analysis including reanalysis of original participant data.To identify suitable studies, MEDLINE, Embase, and PsycINFO and preexisting study consortia were searched from inception to December 2017. Authors of prospective longitudinal human studies or trials of antihypertensives were contacted for data sharing and collaboration. Outcome measures were incident dementia or incident cognitive decline (classified using the reliable change index method). Data were separated into mid and late-life (>65 years) and each antihypertensive class was compared to no treatment and to treatment with other antihypertensives. Meta-analysis was used to synthesize data.Over 50,000 participants from 27 studies were included. Among those aged >65 years, with the exception of diuretics, we found no relationship by class with incident cognitive decline or dementia. Diuretic use was suggestive of benefit in some analyses but results were not consistent across follow-up time, comparator group, and outcome. Limited data precluded meaningful analyses in those ≤65 years of age.Our findings, drawn from the current evidence base, support clinical freedom in the selection of antihypertensive regimens to achieve blood pressure goals.The review was registered with the international prospective register of systematic reviews (PROSPERO), registration number CRD42016045454.
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| 13. |
- Richard, Edo, et al.
(author)
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Healthy Ageing Through Internet Counselling in the Elderly : the HATICE randomised controlled trial for the prevention of cardiovascular disease and cognitive impairment
- 2016
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In: BMJ Open. - : BMJ. - 2044-6055. ; 6:6
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Journal article (peer-reviewed)abstract
- Introduction Cardiovascular disease and dementia share a number of risk factors including hypertension, hypercholesterolaemia, smoking, obesity, diabetes and physical inactivity. The rise of eHealth has led to increasing opportunities for large-scale delivery of prevention programmes encouraging self-management. The aim of this study is to investigate whether a multidomain intervention to optimise self-management of cardiovascular risk factors in older individuals, delivered through an coach-supported interactive internet platform, can improve the cardiovascular risk profile and reduce the risk of cardiovascular disease and cognitive decline. Methods and analysis HATICE is a multinational, multicentre, prospective, randomised, open-label blinded end point (PROBE) trial with 18months intervention. Recruitment of 2600 older people (65years) at increased risk of cardiovascular disease will take place in the Netherlands, Finland and France. Participants randomised to the intervention condition will have access to an interactive internet platform, stimulating self-management of vascular risk factors, with remote support by a coach. Participants in the control group will have access to a static internet platform with basic health information. The primary outcome is a composite score based on the average z-score of the difference between baseline and 18months follow-up values of systolic blood pressure, low-density-lipoprotein and body mass index. Main secondary outcomes include the effect on the individual components of the primary outcome, the effect on lifestyle-related risk factors, incident cardiovascular disease, mortality, cognitive functioning, mood and cost-effectiveness.
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| 14. |
- Richard, Edo, et al.
(author)
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Healthy ageing through internet counselling in the elderly (HATICE) : a multinational, randomised controlled trial
- 2019
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In: The Lancet Digital Health. - 2589-7500. ; 1:8, s. e424-e434
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Journal article (peer-reviewed)abstract
- Background Although web-based interventions have been promoted for cardiovascular risk management over the past decade, there is limited evidence for effectiveness of these interventions in people older than 65 years. The healthy ageing through internet counselling in the elderly (HATICE) trial aimed to determine whether a coach-supported internet intervention for self-management can reduce cardiovascular risk in community-dwelling older people.Methods This prospective open-label, blinded endpoint clinical trial among people age 65 years or over at increased risk of cardiovascular disease randomly assigned participants in the Netherlands, Finland, and France to an interactive internet intervention stimulating coach-supported self-management or a control platform. Primary outcome was the difference from baseline to 18 months on a standardised composite score (Z score) of systolic blood pressure, LDL cholesterol, and body-mass index (BMI). Secondary outcomes included individual risk factors and cardiovascular endpoints. This trial is registered with the ISRCTN registry, 48151589, and is closed to accrual.Findings Among 2724 participants, complete primary outcome data were available for 2398 (88%). After 18 months, the primary outcome improved in the intervention group versus the control group (0.09 vs 0.04, respectively; mean difference -0.05, 95% CI -0.08 to -0.01; p=0.008). For individual components of the primary outcome, mean differences (intervention vs control) were systolic blood pressure -1.79 mm Hg versus -0.67 mm Hg (-1.12, -2.51 to 0.27); BMI -0.23 kg/m(2) versus -0.08 kg/m(2) (-0.15, -0.28 to -0.01); and LDL -0.12 mmol/L versus -0.07 mmol/L (-0.05, -0.11 to 0.01). Cardiovascular disease occurred in 30 (2.2%) of 1382 patients in the intervention versus 32 (2.4%) of 1333 patients in the control group (hazard ratio 0.86, 95% CI 0.52 to 1.43).Interpretation Coach-supported self-management of cardiovascular risk factors using an interactive internet intervention is feasible in an older population, and leads to a modest improvement of cardiovascular risk profile. When implemented on a large scale this could potentially reduce the burden of cardiovascular disease.
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| 15. |
- Richard, Edo, et al.
(author)
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Methodological challenges in designing dementia prevention trials - The European Dementia Prevention Initiative (EDPI)
- 2012
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In: Journal of the Neurological Sciences. - : Elsevier BV. - 0022-510X .- 1878-5883. ; 322:1-2, s. 64-70
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Journal article (peer-reviewed)abstract
- Recent epidemiological studies have indicated numerous associations between vascular and lifestyle related risk factors and incident dementia. However, evidence from randomised controlled trials (RCT) showing effectiveness of interventions aimed at these risk factors in preventing or postponing dementia onset is still lacking. Three large RDT on multi-component interventions to prevent dementia (preDIVA, FINGER. MAPT) have been initiated in Europe to address these issues. Irrespective of some methodological differences, all three studies target cardiovascular and lifestyle related risk factors. Collaboration within the newly founded 'European Dementia Prevention Initiative' (EDPI) will allow for a comprehensive exploration of optimal target population, intervention and outcome measures, which are currently unknown. Combining data of the ongoing studies and running simulation analyses will facilitate determining the optimal design including accurate sample-size calculations for future multi-national clinical trials on dementia prevention. Interventions aiming at dementia prevention should be pragmatic and easy to implement on a large scale in different health care systems, without generating high additional costs or burden on participants or physicians. As the optimal age for intervention precedes the optimal age for outcome assessment, traditional trial designs might lead to suboptimal timing of either of the two. Separation of intervention and outcome assessment in time is a potential solution, but requires studies with very long follow-up. International collaboration of research groups with experience in dementia prevention studies and well-organised logistics for these major projects is pivotal to success for future large-scale dementia prevention studies. Founding of EDPI is an important first step in this direction.
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| 16. |
- van Dalen, Jan Willem, et al.
(author)
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Association of Systolic Blood Pressure With Dementia Risk and the Role of Age, U-Shaped Associations, and Mortality.
- 2022
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In: JAMA internal medicine. - : American Medical Association (AMA). - 2168-6114 .- 2168-6106. ; 182:2, s. 142-152
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Journal article (peer-reviewed)abstract
- The optimal systolic blood pressure (SBP) to minimize the risk of dementia in older age is unknown.To investigate whether the association between SBP and dementia risk is U-shaped and whether age and comorbidity play a role in this association.This cohort study used an individual participant data approach to analyze 7 prospective, observational, population-based cohort studies that were designed to evaluate incident dementia in older adults. These studies started between 1987 and 2006 in Europe and the US. Participants had no dementia diagnosis and had SBP and/or diastolic blood pressure (BP) data at baseline and incident dementia status during follow-up. Data analysis was conducted from November 7, 2019, to October 3, 2021.Baseline systolic BP.All-cause dementia (defined using Diagnostic and Statistical Manual of Mental Disorders [Third Edition Revised] or Diagnostic and Statistical Manual of Mental Disorders [Fourth Edition] and established at follow-up measurements or in clinical practice), mortality, and combined dementia and mortality were the outcomes. Covariates included baseline antihypertensive medication use, sex, educational level, body mass index, smoking status, diabetes, stroke history, myocardial infarction history, and polypharmacy. Cox proportional hazards regression models were used, and nonlinear associations were explored using natural splines.The study analyzed 7 cohort studies with a total of 17286 participants, among whom 10393 were women (60.1%) and the mean (SD) baseline age was 74.5 (7.3) years. Overall, dementia risk was lower for individuals with higher SBP, with the lowest risk associated with an SBP of approximately 185 mm Hg (95% CI, 161-230 mm Hg; P=.001). Stratified by overlapping 10-year baseline age groups, the lowest dementia risk was observed at somewhat lower systolic BP levels in those older than 75 years (158 [95% CI, 152-178] mm Hg to 170 [95% CI, 160-260] mm Hg). For mortality, there was a clear U-shaped association, with the lowest risk at 160 mm Hg (95% CI, 154-181 mm Hg; P<.001). This U-shape occurred across all age groups, with the lowest dementia risk associated with an SBP of 134 mm Hg (95% CI, 102-149 mm Hg; P=.03) in those aged 60 to 70 years and increasing to between 155 mm Hg (95% CI, 150-166 mm Hg; P<.001) and 166 mm Hg (95% CI, 154-260 mm Hg; P=.02) for age groups between 70 and 95 years. Combined dementia and mortality risk curves closely resembled those for mortality. Associations of diastolic BP with dementia risk were generally similar but were less distinct.This cohort study found that dementia risk was lower for older individuals with higher SBP levels and that more distinctly U-shaped associations appeared for those older than 75 years, but these associations cannot be explained by SBP-associated changes in mortality risk. The findings may warrant future trials on tailored BP management in older age groups that take life expectancy and health context into consideration.
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| 17. |
- van Wanrooij, Lennard L., et al.
(author)
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Pooling individual participant data from randomized controlled trials : Exploring potential loss of information
- 2020
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:5
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Journal article (peer-reviewed)abstract
- Background Pooling individual participant data to enable pooled analyses is often complicated by diversity in variables across available datasets. Therefore, recoding original variables is often necessary to build a pooled dataset. We aimed to quantify how much information is lost in this process and to what extent this jeopardizes validity of analyses results. Methods Data were derived from a platform that was developed to pool data from three randomized controlled trials on the effect of treatment of cardiovascular risk factors on cognitive decline or dementia. We quantified loss of information using the R-squared of linear regression models with pooled variables as a function of their original variable(s). In case the R-squared was below 0.8, we additionally explored the potential impact of loss of information for future analyses. We did this second step by comparing whether the Beta coefficient of the predictor differed more than 10% when adding original or recoded variables as a confounder in a linear regression model. In a simulation we randomly sampled numbers, recoded those < = 1000 to 0 and those > 1000 to 1 and varied the range of the continuous variable, the ratio of recoded zeroes to recoded ones, or both, and again extracted the R-squared from linear models to quantify information loss. Results The R-squared was below 0.8 for 8 out of 91 recoded variables. In 4 cases this had a substantial impact on the regression models, particularly when a continuous variable was recoded into a discrete variable. Our simulation showed that the least information is lost when the ratio of recoded zeroes to ones is 1:1. Conclusions Large, pooled datasets provide great opportunities, justifying the efforts for data harmonization. Still, caution is warranted when using recoded variables which variance is explained limitedly by their original variables as this may jeopardize the validity of study results.
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| 18. |
- Varg, Javier Edo, 1988-, et al.
(author)
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Microplastic exposure across trophic levels : effects on the host microbiota of freshwater organisms
- 2022
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In: Environmental Microbiome. - : Springer Nature. - 2524-6372. ; 17:1
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Journal article (peer-reviewed)abstract
- BackgroundMicroplastics are a pervasive pollutant widespread in the sea and freshwater from anthropogenic sources, and together with the presence of pesticides, they can have physical and chemical effects on aquatic organisms and on their microbiota. Few studies have explored the combined effects of microplastics and pesticides on the host–microbiome, and more importantly, the effects across multiple trophic levels. In this work, we studied the effects of exposure to microplastics and the pesticide deltamethrin on the diversity and abundance of the host–microbiome across a three-level food chain: daphnids–damselfly–dragonflies. Daphnids were the only organism exposed to 1 µm microplastic beads, and they were fed to damselfly larvae. Those damselfly larvae were exposed to deltamethrin and then fed to the dragonfly larvae. The microbiotas of the daphnids, damselflies, and dragonflies were analyzed.ResultsExposure to microplastics and deltamethrin had a direct effect on the microbiome of the species exposed to these pollutants. An indirect effect was also found since exposure to the pollutants at lower trophic levels showed carry over effects on the diversity and abundance of the microbiome on higher trophic levels, even though the organisms at these levels where not directly exposed to the pollutants. Moreover, the exposure to deltamethrin on the damselflies negatively affected their survival rate in the presence of the dragonfly predator, but no such effects were found on damselflies fed with daphnids that had been exposed to microplastics.ConclusionsOur study highlights the importance of evaluating ecotoxicological effects at the community level. Importantly, the indirect exposure to microplastics and pesticides through diet can potentially have bottom-up effects on the trophic webs.
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| 19. |
- Varg, Javier Edo, 1988-, et al.
(author)
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Multi stress system : Microplastics in freshwater and their effects on host microbiota
- 2023
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In: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 856:Part 2
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Journal article (peer-reviewed)abstract
- Microplastics are persistent and complex contaminants that have recently been found in freshwater systems, raising concerns about their presence in aquatic organisms. Plastics tend to be seen as an inert material; however, it is not well known if exposure to plastics for a prolonged time, in combination with organic chemicals, causes organism mortality. Ingestion of microplastics in combination with another pollutant may affect a host organism's fitness by altering the host microbiome. In this study, we investigated how microplastics interact with other pollutants in this multi-stress system, and whether they have a synergistic impact on the mortality of an aquatic organism and its microbiome. We used wild water boatmen Hemiptera (Corixidae) found at lake Erken located in east-central Sweden in a fully factorial two-way microcosm experiment designed with polystyrene microspheres and a commonly used detergent. The microplastic-detergent interaction is manifested as a significant increase in mortality compared to the other treatments at 48 h of exposure. The diversity of the microbial communities in the water was significantly affected by the combined treatment of microplastics and the detergent while the microbial communities in the host were affected by the treatments with microplastics and the detergent alone. Changes in relative abundance in Gammaproteobacteria (family Enterobacteriaceae), were observed in the perturbed treatments mostly associated with the presence of the detergent. This confirms that microplastics can interact with detergents having toxic effects on wild water boatmen. Furthermore, microplastics may impact wild organisms via changes in their microbial communities.
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| 20. |
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| 21. |
- Varg, Javier Edo, 1988-, et al.
(author)
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Single and combined effects of microplastics, pyrethroid and food resources on the life-history traits and microbiome of Chironomus riparius
- 2021
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In: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 289
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Journal article (peer-reviewed)abstract
- There is growing evidence of widespread contamination of freshwater ecosystems with microplastics. However, the effects of chronic microplastic ingestion and its interaction with other pollutants and stress factors on the life history traits and the host-microbiome of aquatic invertebrates are not well understood. This study investigates the effects of exposure to sediment spiked with 1 mu m polystyrene-based latex microplastic spheres, an environmentally realistic concentration of a pyrethroid pesticide (esfenvalerate), and a combination of both treatments on the life-history traits of the benthic-dwelling invertebrate, Chironomus riparius and its microbial community. The chironomid larvae were also exposed to two food conditions: abundant or limited food in the sediment, monitored for 28 and 34 days respectively. The microplastics and esfenvalerate had negative effects on adult emergence and survival, and these effects differed between the food level treatments. The microbiome diversity was negatively affected by the exposure to microplastics, while the relative abundances of the four top phyla were significantly affected only in the high food level treatment. Although the combined exposure to microplastics and esfenvalerate showed some negative effects on survival and emergence, there was little evidence for synergistic effects when compared to the single exposure. The food level affected all life-history traits and the microbiota, and lower food levels intensified the negative effects of the exposure to microplastics, esfenvalerate and their combination. We argue that these pollutants can affect crucial life-history traits such as successful metamorphosis and the host-microbiome. Therefore, it should be taken into consideration for toxicological assessment of pollutant acceptability. Our study highlights the importance of investigating possible additive and synergic activities between stressors to understand the effects of pollutants in the life story traits and host-microbiome.
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| 22. |
- Varg, Javier Edo, 1988-
(author)
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The effects of exposure to microplastics and pollutants on the arthropod microbiome
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Anthropogenic pollution is widespread across various ecosystems. This disturbance can alter the interaction between a host and its associated microbiome, with repercussions for hosts traits such as health, behavior, and host evolution. The thesis aim is to understand the effects of inert microplastics and other pollutants, as pesticides, detergents, and toxic metals, on the host-microbiota of different freshwater invertebrates. Specifically, this thesis explores the secondary effects of stress factors on the host, trophic interactions, and free-living microbes. Chapter I tested the effects of microplastics and the pesticide esfenvalerate on Chironomus riparius survival, emergence, and its microbiome. Chapter II tested the effects of microplastics and the pesticide deltamethrin on a trophic chain of three organisms: Daphnia magna, damselfly larva Ischnura elegans, and wild dragonfly larva Aeshna cyanea. Chapter III tested the effects of microplastics and sodium dodecyl sulfate on the microbiome of wild water boatman from the family Corixidae. Chapter IV tested the effects of microplastics and Chromium VI on Daphnia magna mortality and its microbiome. The thesis used metagenomic tools to characterize both the host microbiome and its surrounding microcosms. Our results showed that microplastics interact with additive toxicants to affect the host microbiome, however, these effects depend on the type of toxicant, the size of the microplastic, and the host itself.
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| 23. |
- Varg, Javier Edo, 1988-, et al.
(author)
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The stressful effects of microplastics associated with chromium (VI) on the microbiota of Daphnia Magna
- 2022
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In: Frontiers in Environmental Science. - : Frontiers Media S.A.. - 2296-665X. ; 10
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Journal article (peer-reviewed)abstract
- Contamination by microplastics (particles < 1 mm) is a growing and alarming environmental problem in freshwater systems. Evidence suggests that industrial effluents could be one of the critical point sources of microplastics and other pollutants, and their interaction can cause organismal stress and affect host and environmental microbial communities. We tested the individual and combined effects of microplastics and other pollutants on host survival and host associated (commensal) bacterial diversity. We exposed Daphnia magna to 1 µm microplastic beads with a concentration of approximately 1820 particles/ml and chromium (VI) simultaneously with treatments of 2 and 5 ppm for 72 h. DNA extraction was done to amplify and sequence the ribosomal Bacterial 16S from both the water and the Daphnia. Daphnia experienced low mortality in treatments microplastics (13.3%) and 2 ppm chromium VI (30%) individually. However, the combination of microplastics and 2 ppm chromium (VI) increased the mortality to 74.4%. In the treatments with 5 ppm of chromium (VI) mortality rose to 100% after 30 h of exposure. Microbial diversity changed in response to microplastics, chromium (VI), and both combined exposure. Microplastics and toxic metals can cause dysbiosis of freshwater environmental microbiota, whole host microbiota, and host survival. This work stresses the importance to assess how pollutants’ individual and joint effects could affect organisms including their microbiome.
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| 24. |
- Villar, V. Ashley, et al.
(author)
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SuperRAENN : A Semisupervised Supernova Photometric Classification Pipeline Trained on Pan-STARRS1 Medium-Deep Survey Supernovae
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 905:2
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Journal article (peer-reviewed)abstract
- Automated classification of supernovae (SNe) based on optical photometric light-curve information is essential in the upcoming era of wide-field time domain surveys, such as the Legacy Survey of Space and Time (LSST) conducted by the Rubin Observatory. Photometric classification can enable real-time identification of interesting events for extended multiwavelength follow-up, as well as archival population studies. Here we present the complete sample of 5243 SN-like light curves (in g(P1)r(P1)i(P1)z(P1)) from the Pan-STARRS1 Medium-Deep Survey (PS1-MDS). The PS1-MDS is similar to the planned LSST Wide-Fast-Deep survey in terms of cadence, filters, and depth, making this a useful training set for the community. Using this data set, we train a novel semisupervised machine learning algorithm to photometrically classify 2315 new SN-like light curves with host galaxy spectroscopic redshifts. Our algorithm consists of an RF supervised classification step and a novel unsupervised step in which we introduce a recurrent autoencoder neural network (RAENN). Our final pipeline, dubbed SuperRAENN, has an accuracy of 87% across five SN classes (Type Ia, Ibc, II, IIn, SLSN-I) and macro-averaged purity and completeness of 66% and 69%, respectively. We find the highest accuracy rates for SNe Ia and SLSNe and the lowest for SNe Ibc. Our complete spectroscopically and photometrically classified samples break down into 62.0% Type Ia (1839 objects), 19.8% Type II (553 objects), 4.8% Type IIn (136 objects), 11.7% Type Ibc (291 objects), and 1.6% Type I SLSNe (54 objects).
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| 25. |
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- 2017
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In: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
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Journal article (peer-reviewed)
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