| 1. |
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| 2. |
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| 3. |
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| 4. |
- Hall, C. Michael, et al.
(författare)
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Denying bogus skepticism in climate change and tourism research.
- 2015
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Ingår i: Tourism Management. - : Elsevier BV. - 0261-5177 .- 1879-3193. ; 47, s. 352-356
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Tidskriftsartikel (refereegranskat)abstract
- This final response to the two climate change denial papers by Shani and Arad further highlights the inaccuracies, misinformation and errors in their commentaries. The obfuscation of scientific research and the consensus on anthropogenic climate change may have significant long-term negative consequences for better understanding the implications of climate change and climate policy for tourism and create confusion and delay in developing and implementing tourism sector responses.
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| 5. |
- Hall, C. Michael, et al.
(författare)
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No time for smokescreen skepticism : A rejoinder to Shani and Arad
- 2015
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Ingår i: Tourism Management. - : Elsevier BV. - 0261-5177 .- 1879-3193. ; 47, s. 341-347
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Tidskriftsartikel (refereegranskat)abstract
- Shani and Arad (2014) claimed that tourism scholars tend to endorse the most pessimistic assessments regarding climate change, and that anthropogenic climate change was a "fashionable" and "highly controversial scientific topic". This brief rejoinder provides the balance that is missing from such climate change denial and skepticism studies on climate change and tourism. Recent research provides substantial evidence that reports on anthropogenic climate change are accurate, and that human-induced greenhouse gas emissions, including from the tourism industry, play a significant role in climate change. Some positive net effects may be experienced by some destinations in the short-term, but in the long-term all elements of the tourism system will be impacted. The expansion of tourism emissions at a rate greater than efficiency gains means that it is increasingly urgent that the tourism sector acknowledge, accept and respond to climate change. Debate on tourism-related adaptation and mitigation measures is to be encouraged and welcomed. Climate change denial is not.
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| 6. |
- Marçal, L. A.B., et al.
(författare)
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Structural and chemical properties of anion exchanged CsPb(Br(1−x)Cl x )3 heterostructured perovskite nanowires imaged by nanofocused x-rays
- 2024
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Ingår i: Nanotechnology. - 0957-4484. ; 35:26
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Tidskriftsartikel (refereegranskat)abstract
- Over the last years metal halide perovskites have demonstrated remarkable potential for integration in light emitting devices. Heterostructures allow for tunable bandgap depending on the local anion composition, crucial for optoelectronic devices, but local structural effects of anion exchange in single crystals is not fully understood. Here, we investigate how the anion exchange of CsPbBr3 nanowires fully and locally exposed to HCl vapor affects the local crystal structure, using nanofocused x-rays. We study the nanoscale composition and crystal structure as function of HCl exposure time and demonstrate the correlation of anion exchange with changes in the lattice parameter. The local composition was measured by x-ray fluorescence and x-ray diffraction, with general agreement of both methods but with much less variation using latter. The heterostructured nanowires exhibit unintentional gradients in composition, both axially and radially. Ferroelastic domains are observed for all HCl exposure times, and the magnitude of the lattice tilt at the domain walls scales with the Cl concentration.
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| 7. |
- Bartels, M., et al.
(författare)
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Childhood aggression and the co-occurrence of behavioural and emotional problems: results across ages 3-16years from multiple raters in six cohorts in the EU-ACTION project
- 2018
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Ingår i: European Child & Adolescent Psychiatry. - : Springer Science and Business Media LLC. - 1018-8827 .- 1435-165X. ; 27:9, s. 1105-1121
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Tidskriftsartikel (refereegranskat)abstract
- Childhood aggression and its resulting consequences inflict a huge burden on affected children, their relatives, teachers, peers and society as a whole. Aggression during childhood rarely occurs in isolation and is correlated with other symptoms of childhood psychopathology. In this paper, we aim to describe and improve the understanding of the co-occurrence of aggression with other forms of childhood psychopathology. We focus on the co-occurrence of aggression and other childhood behavioural and emotional problems, including other externalising problems, attention problems and anxiety-depression. The data were brought together within the EU-ACTION (Aggression in Children: unravelling gene-environment interplay to inform Treatment and InterventiON strategies) project. We analysed the co-occurrence of aggression and other childhood behavioural and emotional problems as a function of the child's age (ages 3 through 16years), gender, the person rating the behaviour (father, mother or self) and assessment instrument. The data came from six large population-based European cohort studies from the Netherlands (2x), the UK, Finland and Sweden (2x). Multiple assessment instruments, including the Child Behaviour Checklist (CBCL), the Strengths and Difficulties Questionnaire (SDQ) and Multidimensional Peer Nomination Inventory (MPNI), were used. There was a good representation of boys and girls in each age category, with data for 30,523 3- to 4-year-olds (49.5% boys), 20,958 5- to 6-year-olds (49.6% boys), 18,291 7- to 8-year-olds (49.0% boys), 27,218 9- to 10-year-olds (49.4% boys), 18,543 12- to 13-year-olds (48.9% boys) and 10,088 15- to 16-year-olds (46.6% boys). We replicated the well-established gender differences in average aggression scores at most ages for parental ratings. The gender differences decreased with age and were not present for self-reports. Aggression co-occurred with the majority of other behavioural and social problems, from both externalising and internalising domains. At each age, the co-occurrence was particularly prevalent for aggression and oppositional and ADHD-related problems, with correlations of around 0.5 in general. Aggression also showed substantial associations with anxiety-depression and other internalizing symptoms (correlations around 0.4). Co-occurrence for self-reported problems was somewhat higher than for parental reports, but we found neither rater differences, nor differences across assessment instruments in co-occurrence patterns. There were large similarities in co-occurrence patterns across the different European countries. Finally, co-occurrence was generally stable across age and sex, and if any change was observed, it indicated stronger correlations when children grew older. We present an online tool to visualise these associations as a function of rater, gender, instrument and cohort. In addition, we present a description of the full EU-ACTION projects, its first results and the future perspectives.
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| 8. |
- Campieri, M, et al.
(författare)
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Oral budesonide is as effective as oral prednisolone in active Crohn's disease. The Global Budesonide Study Group
- 1997
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Ingår i: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 41:2, s. 209-214
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Tidskriftsartikel (refereegranskat)abstract
- Background—The use of corticosteroids in active Crohn’s disease often becomes limited by side effects. Budesonide is a potent corticosteroid with low systemic bioavailability due to an extensive first pass liver metabolism.Aims—To compare the efficacy and safety of two dosage regimens of budesonide and prednisolone in patients with active Crohn’s disease affecting the ileum and/or the ascending colon.Patients and methods—One hundred and seventy eight patients were randomised to receive budesonide controlled ileal release (CIR) capsules 9 mg once daily or 4.5 mg twice daily, or prednisolone tablets 40 mg once daily. The treatment period was 12 weeks. The primary efficacy variable was clinical remission, defined as a Crohn’s Disease Activity Index (CDAI) of 150 or less.Results—After eight weeks of treatment, remission occurred in 60% of patients receiving budesonide once daily or prednisolone and in 42% of those receiving budesonide twice daily (p=0.062). The presence of glucocorticoid associated side effects was similar in all groups; however, moon face was more common in the prednisolone group (p=0.0005). The highest frequency of impaired adrenal function, as measured by a short ACTH test, was found in the prednisolone group (p=0.0023).Conclusions—Budesonide CIR, administered at 9 mg once daily or 4.5 mg twice daily, is comparable to prednisolone in inducing remission in active Crohn’s disease. The single dose administration is as promptly effective as prednisolone and represents a simpler and safer therapeutic approach, with a considerable reduction in side effects.
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| 9. |
- Burridge, J., et al.
(författare)
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A systematic review of international clinical guidelines for rehabilitation of people with neurological conditions: What recommendations are made for upperlimb assessment?
- 2019
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Upper limb impairment is a common problem for people with neurological disabilities, affecting activity, performance, quality of life, and independence. Accurate, timely assessments are required for effective rehabilitation, and development of novel interventions. International consensus on upper limb assessment is needed to make research findings more meaningful, provide a benchmark for quality in clinical practice, more cost-effective neurorehabilitation and improved outcomes for neurological patients undergoing rehabilitation. Aim: To conduct a systematic review, as part of the output of a European COST Action, to identify what recommendations are made for upper limb assessment. Methods: We systematically reviewed published guidance on measures and protocols for assessment of upper limb function in neurological rehabilitation via electronic databases from January 2007-December 2017. Additional records were then identified through other sources. Records were selected for inclusion based on scanning of titles, abstracts and full text by two authors working independently, and a third author if there was disagreement. Records were included if they referred to "rehabilitation" and "assessment" or "measurement". Reasons for exclusion were documented. Results: From the initial 552 records identified (after duplicates were removed), 34 satisfied our criteria for inclusion, and only six recommended specific outcome measures and /or protocols. Records were divided into National Guidelines and other practice guidelines published in peer reviewed Journals. There was agreement that assessment is critical, should be conducted early and at regular intervals and that there is a need for standardized measures. Assessments should be conducted by a healthcare professional trained in using the measure and should encompass body function and structure, activity and participation. Conclusions: We present a comprehensive, critical, and original summary of current recommendations. Defining a core set of measures and agreed protocols requires international consensus between experts representing the diverse and multi-disciplinary field of neurorehabilitation including clinical researchers and practitioners, rehabilitation technology researchers, and commercial developers. Current lack of guidance may hold-back progress in understanding function and recovery. Together with a Delphi consensus study and an overview of systematic reviews of outcome measures it will contribute to the development of international guidelines for upper limb assessment in neurological conditions. © 2019 Burridge, Alt Murphy, Buurke, Feys, Keller, Klamroth-Marganska, Lamers, McNicholas, Prange, Tarkka, Timmermans and Hughes.
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| 10. |
- Cowie, A. L., et al.
(författare)
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Applying a science-based systems perspective to dispel misconceptions about climate effects of forest bioenergy
- 2021
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Ingår i: Global Change Biology Bioenergy. - : John Wiley and Sons Inc. - 1757-1693 .- 1757-1707. ; 13:8, s. 1210-1231
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Tidskriftsartikel (refereegranskat)abstract
- The scientific literature contains contrasting findings about the climate effects of forest bioenergy, partly due to the wide diversity of bioenergy systems and associated contexts, but also due to differences in assessment methods. The climate effects of bioenergy must be accurately assessed to inform policy-making, but the complexity of bioenergy systems and associated land, industry and energy systems raises challenges for assessment. We examine misconceptions about climate effects of forest bioenergy and discuss important considerations in assessing these effects and devising measures to incentivize sustainable bioenergy as a component of climate policy. The temporal and spatial system boundary and the reference (counterfactual) scenarios are key methodology choices that strongly influence results. Focussing on carbon balances of individual forest stands and comparing emissions at the point of combustion neglect system-level interactions that influence the climate effects of forest bioenergy. We highlight the need for a systems approach, in assessing options and developing policy for forest bioenergy that: (1) considers the whole life cycle of bioenergy systems, including effects of the associated forest management and harvesting on landscape carbon balances; (2) identifies how forest bioenergy can best be deployed to support energy system transformation required to achieve climate goals; and (3) incentivizes those forest bioenergy systems that augment the mitigation value of the forest sector as a whole. Emphasis on short-term emissions reduction targets can lead to decisions that make medium- to long-term climate goals more difficult to achieve. The most important climate change mitigation measure is the transformation of energy, industry and transport systems so that fossil carbon remains underground. Narrow perspectives obscure the significant role that bioenergy can play by displacing fossil fuels now, and supporting energy system transition. Greater transparency and consistency is needed in greenhouse gas reporting and accounting related to bioenergy.
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| 11. |
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| 12. |
- Hughes, A. M., et al.
(författare)
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Evaluation of upper extremity neurorehabilitation using technology: a European Delphi consensus study within the EU COST Action Network on Robotics for Neurorehabilitation
- 2016
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Ingår i: Journal of Neuroengineering and Rehabilitation. - : Springer Science and Business Media LLC. - 1743-0003. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background: The need for cost-effective neurorehabilitation is driving investment into technologies for patient assessment and treatment. Translation of these technologies into clinical practice is limited by a paucity of evidence for cost-effectiveness. Methodological issues, including lack of agreement on assessment methods, limit the value of meta-analyses of trials. In this paper we report the consensus reached on assessment protocols and outcome measures for evaluation of the upper extremity in neurorehabilitation using technology. The outcomes of this research will be part of the development of European guidelines. Methods: A rigorous, systematic and comprehensive modified Delphi study incorporated questions and statements generation, design and piloting of consensus questionnaire and five consensus experts groups consisting of clinicians, clinical researchers, non-clinical researchers, and engineers, all with working experience of neurological assessments or technologies. For data analysis, two major groups were created: i) clinicians (e.g., practicing therapists and medical doctors) and ii) researchers (clinical and non-clinical researchers (e.g. movement scientists, technology developers and engineers). Results: Fifteen questions or statements were identified during an initial ideas generation round, following which the questionnaire was designed and piloted. Subsequently, questions and statements went through five consensus rounds over 20 months in four European countries. Two hundred eight participants: 60 clinicians (29 %), 35 clinical researchers (17 %), 77 non-clinical researchers (37 %) and 35 engineers (17 %) contributed. At each round questions and statements were added and others removed. Consensus (>= 69 %) was obtained for 22 statements on i) the perceived importance of recommendations; ii) the purpose of measurement; iii) use of a minimum set of measures; iv) minimum number, timing and duration of assessments; v) use of technology-generated assessments and the restriction of clinical assessments to validated outcome measures except in certain circumstances for research. Conclusions: Consensus was reached by a large international multidisciplinary expert panel on measures and protocols for assessment of the upper limb in research and clinical practice. Our results will inform the development of best practice for upper extremity assessment using technologies, and the formulation of evidence-based guidelines for the evaluation of upper extremity neurorehabilitation.
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| 13. |
- Koenig, Julian, et al.
(författare)
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Cortical thickness and resting-state cardiac function across the lifespan : A cross-sectional pooled mega-analysis
- 2021
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Ingår i: Psychophysiology. - : Wiley. - 0048-5772 .- 1469-8986 .- 1540-5958. ; 58:7
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the association between autonomic nervous system [ANS] function and brain morphology across the lifespan provides important insights into neurovisceral mechanisms underlying health and disease. Resting-state ANS activity, indexed by measures of heart rate [HR] and its variability [HRV] has been associated with brain morphology, particularly cortical thickness [CT]. While findings have been mixed regarding the anatomical distribution and direction of the associations, these inconsistencies may be due to sex and age differences in HR/HRV and CT. Previous studies have been limited by small sample sizes, which impede the assessment of sex differences and aging effects on the association between ANS function and CT. To overcome these limitations, 20 groups worldwide contributed data collected under similar protocols of CT assessment and HR/HRV recording to be pooled in a mega-analysis (N = 1,218 (50.5% female), mean age 36.7 years (range: 12–87)). Findings suggest a decline in HRV as well as CT with increasing age. CT, particularly in the orbitofrontal cortex, explained additional variance in HRV, beyond the effects of aging. This pattern of results may suggest that the decline in HRV with increasing age is related to a decline in orbitofrontal CT. These effects were independent of sex and specific to HRV; with no significant association between CT and HR. Greater CT across the adult lifespan may be vital for the maintenance of healthy cardiac regulation via the ANS—or greater cardiac vagal activity as indirectly reflected in HRV may slow brain atrophy. Findings reveal an important association between CT and cardiac parasympathetic activity with implications for healthy aging and longevity that should be studied further in longitudinal research.
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| 14. |
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| 15. |
- Prange-Lasonder, G. B., et al.
(författare)
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European evidence-based recommendations for clinical assessment of upper limb in neurorehabilitation (CAULIN): data synthesis from systematic reviews, clinical practice guidelines and expert consensus
- 2021
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Ingår i: Journal of NeuroEngineering and Rehabilitation. - : Springer Science and Business Media LLC. - 1743-0003. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Technology-supported rehabilitation can help alleviate the increasing need for cost-effective rehabilitation of neurological conditions, but use in clinical practice remains limited. Agreement on a core set of reliable, valid and accessible outcome measures to assess rehabilitation outcomes is needed to generate strong evidence about effectiveness of rehabilitation approaches, including technologies. This paper collates and synthesizes a core set from multiple sources; combining existing evidence, clinical practice guidelines and expert consensus into European recommendations for Clinical Assessment of Upper Limb In Neurorehabilitation (CAULIN). Methods Data from systematic reviews, clinical practice guidelines and expert consensus (Delphi methodology) were systematically extracted and synthesized using strength of evidence rating criteria, in addition to recommendations on assessment procedures. Three sets were defined: a core set: strong evidence for validity, reliability, responsiveness and clinical utility AND recommended by at least two sources; an extended set: strong evidence OR recommended by at least two sources and a supplementary set: some evidence OR recommended by at least one of the sources. Results In total, 12 measures (with primary focus on stroke) were included, encompassing body function and activity level of the International Classification of Functioning and Health. The core set recommended for clinical practice and research: Fugl-Meyer Assessment of Upper Extremity (FMA-UE) and Action Research Arm Test (ARAT); the extended set recommended for clinical practice and/or clinical research: kinematic measures, Box and Block Test (BBT), Chedoke Arm Hand Activity Inventory (CAHAI), Wolf Motor Function Test (WMFT), Nine Hole Peg Test (NHPT) and ABILHAND; the supplementary set recommended for research or specific occasions: Motricity Index (MI); Chedoke-McMaster Stroke Assessment (CMSA), Stroke Rehabilitation Assessment Movement (STREAM), Frenchay Arm Test (FAT), Motor Assessment Scale (MAS) and body-worn movement sensors. Assessments should be conducted at pre-defined regular intervals by trained personnel. Global measures should be applied within 24 h of hospital admission and upper limb specific measures within 1 week. Conclusions The CAULIN recommendations for outcome measures and assessment procedures provide a clear, simple, evidence-based three-level structure for upper limb assessment in neurological rehabilitation. Widespread adoption and sustained use will improve quality of clinical practice and facilitate meta-analysis, critical for the advancement of technology-supported neurorehabilitation.
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| 16. |
- Bachmann-Vargas, Pamela, et al.
(författare)
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A social practice approach to nature-based tours : the case of the Marble Caves in Northern Patagonia, Chile
- 2022
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Ingår i: Journal of Ecotourism. - : Routledge. - 1472-4049 .- 1747-7638. ; 21:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Chile’s Northern Patagonia attracts thousands of tourists, who every summer venture to undertake a range of outdoor activities. In this article, we explore the local production of outdoor activities, by conceptualizing small-scale nature-based tours as a social practice. The study is based on empirical research, taking as a case study the development of the Marble Caves tour, an iconic destination in Northern Patagonia, Chile. The touring practice is analyzed based on the interplay of its material components, required competences and symbolic meanings. Our findings demonstrate that the persistence of the practice is particularly reliant on the competences of the tour operators, and on the abiotic nature of the tourist attraction. Fostering tour guide competences therefore contributes to the sustainability and performance of the practice. We contend that tourism policy interventions that aim to harmonize local development and environmental protection need to carefully analyze and take into account existing social practices.
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| 17. |
- Bachmann-Vargas, Pamela, 1983-, et al.
(författare)
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Protecting wilderness or cultural and natural heritage? : Insights from northern Patagonia, Chile
- 2024
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Ingår i: Conservation and Society. - : Wolters Kluwer. - 0972-4923 .- 0975-3133.
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Tidskriftsartikel (refereegranskat)abstract
- Protecting 30% of the planet’s terrestrial and marine ecosystems by 2030 (30x30) is the most recent call for global conservation action. Toward this end, the creation of protected areas is a central strategy. The various parties to the Convention on Biological Diversity (CBD) have committed to this global goal, including Chile. Against this backdrop, this article explores current narratives and practices around five protected areas in northern Patagonia, Chile. We argue that environmental discourses are key to understanding these narratives and practices. Environmental discourses influence the values central to the creation and development of protected areas, as well as the prevailing management approaches for these areas. Our findings show that two discourses are of particular importance: the ‘Patagonian wilderness’ discourse and the ‘cultural and natural heritage’ discourse. Based on our findings, we also discuss three emerging topics: the rewilding and rebranding of Patagonia, optimism around nature-based tourism, and implementation of global conservation goals within the national context. We reflect on the implications of our findings for further developments in Patagonia and for the global conservation debate. We contend that the future of protected-area management in northern Patagonia will depend on how community-based management initiatives are fostered and argue that aligning with such inclusive conservation approaches will be a critical requirement for the implementation of the 30x30 goal moving forward.
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| 18. |
- Bachmann-Vargas, Pamela, et al.
(författare)
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Re-framing salmon aquaculture in the aftermath of the ISAV crisis in Chile
- 2021
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Ingår i: Marine Policy. - : Elsevier. - 0308-597X .- 1872-9460. ; 124
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Tidskriftsartikel (refereegranskat)abstract
- Globally, aquaculture is expanding rapidly, with salmon becoming one of the most dynamic and fast-growing production systems in the world. Despite its commercial success, Chilean salmon production has navigated through severe economic and sanitary crises; followed by consecutive policy changes. Between 2007 and 2009, the rapid spread and the multiple effects of the Infectious Salmon Anemia virus (ISAV) marked a tipping point in the trajectory of the salmon aquaculture in southern Chile. This paper examines the discursive mechanisms through which the Chilean salmon aquaculture industry is currently being re-framed in the aftermath of the ISAV crisis, with a focus on searching for the emergence of ecosystem-related elements post crisis. The analysis shows that Chilean salmon aquaculture is being re-framed by the reproduction of three main discourses: biosecurity, sustainable protein and The Promise of Patagonia. The paper concludes that despite the staggering effects of the ISAV crisis on the national salmon production and on coastal communities more than a decade ago, new discourses are focused on the legitimization to growth, in the absence of integrated marine ecosystem-related elements, indicating a crucial gap toward environmental sustainability in salmon aquaculture.
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| 19. |
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| 20. |
- Duarte-Guterman, P., et al.
(författare)
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Cellular and molecular signatures of motherhood in the adult and ageing rat brain
- 2023
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Ingår i: Open Biology. - 2046-2441. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- Pregnancy is marked by robust changes, including brain changes to volume, structure, connectivity and neuroplasticity. Although some brain changes are restricted to pregnancy and the postpartum, others are long-lasting. Few studies have examined possible mechanisms of these changes or the effects of multiple pregnancies. We characterized various cellular and molecular signatures of parity (nulliparous, primiparous, biparous) in the rat hippocampus. We investigated density of neural stems cells (Sox2), microglia (Iba-1) and levels of a synaptic protein (PSD-95), cell signalling pathways, neuroinflammation, and the tryptophan-kynurenine (TRP-KYN) pathway, one week after weaning their pups from the last pregnancy (age of dam: seven months) and in middle-age (age of dam: 13 months). Parity increased PSD-95 levels in both age groups and prevented the age-related decrease in neural stem cell density observed in nulliparous rats. Biparity increased cell signalling phosphoproteins (pp70S6K, S6RP) and number of microglia in the dentate gyrus, regardless of age. Parity resulted in transient changes to the TRP-KYN system. Thus, previous parity has lasting effects on synaptic plasticity with fewer lasting effects on inflammation and cell signalling phosphoproteins in the whole hippocampus.
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| 21. |
- Gieles, Mark, et al.
(författare)
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Concurrent formation of supermassive stars and globular clusters : Implications for early self-enrichment
- 2018
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Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711. ; 478:2, s. 2461-2479
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Tidskriftsartikel (refereegranskat)abstract
- We present a model for the concurrent formation of globular clusters (GCs) and supermassive stars (SMSs, ≳103M⊙) to address the origin of the HeCNONaMgAl abundance anomalies in GCs. GCs form in converging gas flows and accumulate low-angular momentum gas, which accretes on to protostars. This leads to an adiabatic contraction of the cluster and an increase of the stellar collision rate. A SMS can form via runaway collisions if the cluster reaches sufficiently high density before two-body relaxation halts the contraction. This condition is met if the number of stars ≳106 and the gas accretion rate ≳105M⊙ Myr-1, reminiscent of GC formation in high gas-density environments, such as - but not restricted to - the early Universe. The strong SMS wind mixes with the inflowing pristine gas, such that the protostars accrete diluted hot-hydrogen burning yields of the SMS. Because of continuous rejuvenation, the amount of processed material liberated by the SMS can be an order of magnitude higher than its maximum mass. This 'conveyor-belt' production of hot-hydrogen burning products provides a solution to the mass budget problem that plagues other scenarios. Additionally, the liberated material is mildly enriched in helium and relatively rich in other hot-hydrogen burning products, in agreement with abundances of GCs today. Finally, we find a super-linear scaling between the amount of processed material and cluster mass, providing an explanation for the observed increase of the fraction of processed material with GC mass. We discuss open questions of this new GC enrichment scenario and propose observational tests.
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| 22. |
- Keesman, Rick, et al.
(författare)
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Finite-size scaling at infinite-order phase transitions
- 2016
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Ingår i: Journal of Statistical Mechanics: Theory and Experiment. - : IOP Publishing. - 1742-5468. ; 2016:9, s. 093201-
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Tidskriftsartikel (refereegranskat)abstract
- For systems with infinite-order phase transitions, in which an order parameter smoothly becomes nonzero, a new observable for finite-size scaling analysis is suggested. By construction this new observable has the favourable property of diverging at the critical point. Focussing on the example of the F-model we compare the analysis of this observable with that of another observable, which is also derived from the order parameter but does not diverge, as well as that of the associated susceptibility. We discuss the difficulties that arise in the finite-size scaling analysis of such systems. In particular we show that one may reach incorrect conclusions from large-system size extrapolations of observables that are not known to diverge at the critical point. Our work suggests that one should base finite-size scaling analyses for infinite-order phase transitions only on observables that are guaranteed to diverge.
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| 23. |
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| 24. |
- Temmink, R. J. M., et al.
(författare)
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Mimicry of emergent traits amplifies coastal restoration success
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Restoration is becoming a vital tool to counteract coastal ecosystem degradation. Modifying transplant designs of habitat-forming organisms from dispersed to clumped can amplify coastal restoration yields as it generates self-facilitation from emergent traits, i.e. traits not expressed by individuals or small clones, but that emerge in clumped individuals or large clones. Here, we advance restoration science by mimicking key emergent traits that locally suppress physical stress using biodegradable establishment structures. Experiments across (sub)tropical and temperate seagrass and salt marsh systems demonstrate greatly enhanced yields when individuals are transplanted within structures mimicking emergent traits that suppress waves or sediment mobility. Specifically, belowground mimics of dense root mats most facilitate seagrasses via sediment stabilization, while mimics of aboveground plant structures most facilitate marsh grasses by reducing stem movement. Mimicking key emergent traits may allow upscaling of restoration in many ecosystems that depend on self-facilitation for persistence, by constraining biological material requirements and implementation costs.
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| 25. |
- Van Den Elzen, Eva, et al.
(författare)
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Symbiosis revisited : Phosphorus and acid buffering stimulate N2 fixation but not Sphagnum growth
- 2017
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 14:5, s. 1111-1122
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Tidskriftsartikel (refereegranskat)abstract
- In pristine Sphagnum-dominated peatlands, (di)nitrogen (N2) fixing (diazotrophic) microbial communities associated with Sphagnum mosses contribute substantially to the total nitrogen input, increasing carbon sequestration. The rates of symbiotic nitrogen fixation reported for Sphagnum peatlands, are, however, highly variable, and experimental work on regulating factors that can mechanistically explain this variation is largely lacking. For two common fen species (Sphagnum palustre and S. squarrosum) from a high nitrogen deposition area (25-kg-N-ha-1-yr-1), we found that diazotrophic activity (as measured by 15 - 15N2 labeling) was still present at a rate of 40-nmol N gDW-1-h-1. This was surprising, given that nitrogen fixation is a costly process. We tested the effects of phosphorus availability and buffering capacity by bicarbonate-rich water, mimicking a field situation in fens with stronger groundwater or surface water influence, as potential regulators of nitrogen fixation rates and Sphagnum performance. We expected that the addition of phosphorus, being a limiting nutrient, would stimulate both diazotrophic activity and Sphagnum growth. We indeed found that nitrogen fixation rates were doubled. Plant performance, in contrast, did not increase. Raised bicarbonate levels also enhanced nitrogen fixation, but had a strong negative impact on Sphagnum performance. These results explain the higher nitrogen fixation rates reported for minerotrophic and more nutrient-rich peatlands. In addition, nitrogen fixation was found to strongly depend on light, with rates 10 times higher in light conditions suggesting high reliance on phototrophic organisms for carbon. The contrasting effects of phosphorus and bicarbonate on Sphagnum spp. and their diazotrophic communities reveal strong differences in the optimal niche for both partners with respect to conditions and resources. This suggests a trade-off for the symbiosis of nitrogen fixing microorganisms with their Sphagnum hosts, in which a sheltered environment apparently outweighs the less favorable environmental conditions. We conclude that microbial activity is still nitrogen limited under eutrophic conditions because dissolved nitrogen is being monopolized by Sphagnum. Moreover, the fact that diazotrophic activity can significantly be upregulated by increased phosphorus addition and acid buffering, while Sphagnum spp. do not benefit, reveals remarkable differences in optimal conditions for both symbiotic partners and calls into question the regulation of nitrogen fixation by Sphagnum under these eutrophic conditions. The high nitrogen fixation rates result in high additional nitrogen loading of 6-kg-ha-1-yr-1 on top of the high nitrogen deposition in these ecosystems.
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