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- Freedman, Ben, et al.
(författare)
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Screening for Atrial Fibrillation A Report of the AF-SCREEN International Collaboration
- 2017
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Ingår i: Circulation. - : LIPPINCOTT WILLIAMS & WILKINS. - 0009-7322 .- 1524-4539. ; 135:19, s. 1851-
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Tidskriftsartikel (refereegranskat)abstract
- Approximately 10% of ischemic strokes are associated with atrial fibrillation (AF) first diagnosed at the time of stroke. Detecting asymptomatic AF would provide an opportunity to prevent these strokes by instituting appropriate anticoagulation. The AF-SCREEN international collaboration was formed in September 2015 to promote discussion and research about AF screening as a strategy to reduce stroke and death and to provide advocacy for implementation of country-specific AF screening programs. During 2016, 60 expert members of AF-SCREEN, including physicians, nurses, allied health professionals, health economists, and patient advocates, were invited to prepare sections of a draft document. In August 2016, 51 members met in Rome to discuss the draft document and consider the key points arising from it using a Delphi process. These key points emphasize that screen-detected AF found at a single timepoint or by intermittent ECG recordings over 2 weeks is not a benign condition and, with additional stroke factors, carries sufficient risk of stroke to justify consideration of anticoagulation. With regard to the methods of mass screening, handheld ECG devices have the advantage of providing a verifiable ECG trace that guidelines require for AF diagnosis and would therefore be preferred as screening tools. Certain patient groups, such as those with recent embolic stroke of uncertain source (ESUS), require more intensive monitoring for AF. Settings for screening include various venues in both the community and the clinic, but they must be linked to a pathway for appropriate diagnosis and management for screening to be effective. It is recognized that health resources vary widely between countries and health systems, so the setting for AF screening should be both country-and health system-specific. Based on current knowledge, this white paper provides a strong case for AF screening now while recognizing that large randomized outcomes studies would be helpful to strengthen the evidence base.
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- Schnabel, Renate B., et al.
(författare)
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Searching for Atrial Fibrillation Poststroke : A White Paper of the AF-SCREEN International Collaboration
- 2019
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Ingår i: Circulation. - 1524-4539. ; 140:22, s. 1834-1850
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Tidskriftsartikel (refereegranskat)abstract
- Cardiac thromboembolism attributed to atrial fibrillation (AF) is responsible for up to one-third of ischemic strokes. Stroke may be the first manifestation of previously undetected AF. Given the efficacy of oral anticoagulants in preventing AF-related ischemic strokes, strategies of searching for AF after a stroke using ECG monitoring followed by oral anticoagulation (OAC) treatment have been proposed to prevent recurrent cardioembolic strokes. This white paper by experts from the AF-SCREEN International Collaboration summarizes existing evidence and knowledge gaps on searching for AF after a stroke by using ECG monitoring. New AF can be detected by routine plus intensive ECG monitoring in approximately one-quarter of patients with ischemic stroke. It may be causal, a bystander, or neurogenically induced by the stroke. AF after a stroke is a risk factor for thromboembolism and a strong marker for atrial myopathy. After acute ischemic stroke, patients should undergo 72 hours of electrocardiographic monitoring to detect AF. The diagnosis requires an ECG of sufficient quality for confirmation by a health professional with ECG rhythm expertise. AF detection rate is a function of monitoring duration and quality of analysis, AF episode definition, interval from stroke to monitoring commencement, and patient characteristics including old age, certain ECG alterations, and stroke type. Markers of atrial myopathy (eg, imaging, atrial ectopy, natriuretic peptides) may increase AF yield from monitoring and could be used to guide patient selection for more intensive/prolonged poststroke ECG monitoring. Atrial myopathy without detected AF is not currently sufficient to initiate OAC. The concept of embolic stroke of unknown source is not proven to identify patients who have had a stroke benefitting from empiric OAC treatment. However, some embolic stroke of unknown source subgroups (eg, advanced age, atrial enlargement) might benefit more from non-vitamin K-dependent OAC therapy than aspirin. Fulfilling embolic stroke of unknown source criteria is an indication neither for empiric non-vitamin K-dependent OAC treatment nor for withholding prolonged ECG monitoring for AF. Clinically diagnosed AF after a stroke or a transient ischemic attack is associated with significantly increased risk of recurrent stroke or systemic embolism, in particular, with additional stroke risk factors, and requires OAC rather than antiplatelet therapy. The minimum subclinical AF duration required on ECG monitoring poststroke/transient ischemic attack to recommend OAC therapy is debated.
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| 7. |
- Welling, D. T., et al.
(författare)
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Recommendations for Next-Generation Ground Magnetic Perturbation Validation
- 2018
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Ingår i: Space Weather. - 1542-7390. ; 16:12, s. 1912-1920
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Tidskriftsartikel (refereegranskat)abstract
- Data-model validation of ground magnetic perturbation forecasts, specifically of the time rate of change of surface magnetic field, dB/dt, is a critical task for model development and for mitigation of geomagnetically induced current effects. While a current, community-accepted standard for dB/dt validation exists (Pulkkinen et al., 2013), it has several limitations that prevent more complete understanding of model capability. This work presents recommendations from the International Forum for Space Weather Capabilities Assessment Ground Magnetic Perturbation Working Team for creating a next-generation validation suite. Four recommendations are made to address the existing suite: greatly expand the number of ground observatories used, expand the number of events included in the suite from six to eight, generate metrics as a function of magnetic local time, and generate metrics as a function of activity type. For each of these, implementation details are explored. Limitations and future considerations are also discussed.
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| 8. |
- Axelsson, Christer, et al.
(författare)
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Outcome after out-of-hospital cardiac arrest witnessed by EMS : changes over time and factors of importance for outcome in Sweden.
- 2012
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Ingår i: Resuscitation. - : Elsevier Ireland Ltd. - 0300-9572 .- 1873-1570. ; 83:10, s. 1253-1258
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Tidskriftsartikel (refereegranskat)abstract
- Background Among patients who survive after out-of-hospital cardiac arrest (OHCA), a large proportion are recruited from cases witnessed by the Emergency Medical Service (EMS), since the conditions for success are most optimal in this subset. Aim To evaluate outcome after EMS-witnessed OHCA in a 20-year perspective in Sweden, with the emphasis on changes over time and factors of importance. Methods All patients included in the Swedish Cardiac Arrest Register from 1990 to 2009 were included. Results There were 48,349 patients and 13.5% of them were EMS witnessed. There was a successive increase in EMS-witnessed OHCA from 8.5% in 1992 to 16.9% in 2009 (p for trend < 0.0001). Among EMS-witnessed OHCA, the survival to one month increased from 13.9% in 1992 to 21.8% in 2009 (p for trend < 0.0001). Among EMS-witnessed OHCA, 51% were found in ventricular fibrillation, which was higher than in bystander-witnessed OHCA, despite a lower proportion with a presumed cardiac aetiology in the EMS-witnessed group. Among EMS-witnessed OHCA overall, 16.0% survived to one month, which was significantly higher than among bystander-witnessed OHCA. Independent predictors of a favourable outcome were: (1) initial rhythm ventricular fibrillation; (2) cardiac aetiology; (3) OHCA outside home and (4) decreasing age. Conclusion In Sweden, in a 20-year perspective, there was a successive increase in the proportion of EMS-witnessed OHCA. Among these patients, survival to one month increased over time. EMS-witnessed OHCA had a higher survival than bystander-witnessed OHCA. Independent predictors of an increased chance of survival were initial rhythm, aetiology, place and age.
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- Ringh, M, et al.
(författare)
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The challenges and possibilities of public access defibrillation.
- 2018
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 283:3, s. 238-256
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Tidskriftsartikel (refereegranskat)abstract
- Out-of-hospital cardiac arrest (OHCA) is a major health problem that affects approximately four hundred and thousand patients annually in the United States alone. It is a major challenge for the emergency medical system as decreased survival rates are directly proportional to the time delay from collapse to defibrillation. Historically, defibrillation has only been performed by physicians and in-hospital. With the development of automated external defibrillators (AEDs), rapid defibrillation by nonmedical professionals and subsequently by trained or untrained lay bystanders has become possible. Much hope has been put to the concept of Public Access Defibrillation with a massive dissemination of public available AEDs throughout most Western countries. Accordingly, current guidelines recommend that AEDs should be deployed in places with a high likelihood of OHCA. Despite these efforts, AED use is in most settings anecdotal with little effect on overall OHCA survival. The major reasons for low use of public AEDs are that most OHCAs take place outside high incidence sites of cardiac arrest and that most OHCAs take place in residential settings, currently defined as not suitable for Public Access Defibrillation. However, the use of new technology for identification and recruitment of lay bystanders and nearby AEDs to the scene of the cardiac arrest as well as new methods for strategic AED placement redefines and challenges the current concept and definitions of Public Access Defibrillation. Existing evidence of Public Access Defibrillation and knowledge gaps and future directions to improve outcomes for OHCA are discussed. In addition, a new definition of the different levels of Public Access Defibrillation is offered as well as new strategies for increasing AED use in the society.
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| 18. |
- Rivard, Léna, et al.
(författare)
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Atrial Fibrillation and Dementia : A Report From the AF-SCREEN International Collaboration
- 2022
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Ingår i: Circulation. - 1524-4539. ; 145:5, s. 392-409
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Forskningsöversikt (refereegranskat)abstract
- Growing evidence suggests a consistent association between atrial fibrillation (AF) and cognitive impairment and dementia that is independent of clinical stroke. This report from the AF-SCREEN International Collaboration summarizes the evidence linking AF to cognitive impairment and dementia. It provides guidance on the investigation and management of dementia in patients with AF on the basis of best available evidence. The document also addresses suspected pathophysiologic mechanisms and identifies knowledge gaps for future research. Whereas AF and dementia share numerous risk factors, the association appears to be independent of these variables. Nevertheless, the evidence remains inconclusive regarding a direct causal effect. Several pathophysiologic mechanisms have been proposed, some of which are potentially amenable to early intervention, including cerebral microinfarction, AF-related cerebral hypoperfusion, inflammation, microhemorrhage, brain atrophy, and systemic atherosclerotic vascular disease. The mitigating role of oral anticoagulation in specific subgroups (eg, low stroke risk, short duration or silent AF, after successful AF ablation, or atrial cardiopathy) and the effect of rhythm versus rate control strategies remain unknown. Likewise, screening for AF (in cognitively normal or cognitively impaired patients) and screening for cognitive impairment in patients with AF are debated. The pathophysiology of dementia and therapeutic strategies to reduce cognitive impairment warrant further investigation in individuals with AF. Cognition should be evaluated in future AF studies and integrated with patient-specific outcome priorities and patient preferences. Further large-scale prospective studies and randomized trials are needed to establish whether AF is a risk factor for cognitive impairment, to investigate strategies to prevent dementia, and to determine whether screening for unknown AF followed by targeted therapy might prevent or reduce cognitive impairment and dementia.
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- Dimmock, Andrew P., et al.
(författare)
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Modeling the Geomagnetic Response to the September 2017 Space Weather Event Over Fennoscandia Using the Space Weather Modeling Framework : Studying the Impacts of Spatial Resolution
- 2021
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Ingår i: Space Weather. - : American Geophysical Union (AGU). - 1542-7390. ; 19:5
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Tidskriftsartikel (refereegranskat)abstract
- We must be able to predict and mitigate against geomagnetically induced current (GIC) effects to minimize socio-economic impacts. This study employs the space weather modeling framework (SWMF) to model the geomagnetic response over Fennoscandia to the September 7-8, 2017 event. Of key importance to this study is the effects of spatial resolution in terms of regional forecasts and improved GIC modeling results. Therefore, we ran the model at comparatively low, medium, and high spatial resolutions. The virtual magnetometers from each model run are compared with observations from the IMAGE magnetometer network across various latitudes and over regional-scales. The virtual magnetometer data from the SWMF are coupled with a local ground conductivity model which is used to calculate the geoelectric field and estimate GICs in a Finnish natural gas pipeline. This investigation has lead to several important results in which higher resolution yielded: (1) more realistic amplitudes and timings of GICs, (2) higher amplitude geomagnetic disturbances across latitudes, and (3) increased regional variations in terms of differences between stations. Despite this, substorms remain a significant challenge to surface magnetic field prediction from global magnetohydrodynamic modeling. For example, in the presence of multiple large substorms, the associated large-amplitude depressions were not captured, which caused the largest model-data deviations. The results from this work are of key importance to both modelers and space weather operators. Particularly when the goal is to obtain improved regional forecasts of geomagnetic disturbances and/or more realistic estimates of the geoelectric field.
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| 26. |
- Hollenberg, J, et al.
(författare)
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replik till Bengt Fagrell : Fler hjärtstartare behövs i samhället
- 2013
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Ingår i: Läkartidningen. - : Läkartidningen Förlag AB. - 0023-7205 .- 1652-7518. ; 110:19-20, s. 959-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Fler hjärtstartare behövs, men konceptet behöver utvecklas. Vi måste dessutom finna nya sätt att mobilisera hjärtstartare till platsen för hjärtstoppet.
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- Lutzenkirchen, J., et al.
(författare)
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The surface chemistry of sapphire-c: A literature review and a study on various factors influencing its IEP
- 2018
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686 .- 1873-3727. ; 251, s. 1-25
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Forskningsöversikt (refereegranskat)abstract
- A wide range of isoelectric points (IEPs) has been reported in the literature for sapphire-c (alpha-alumina), also referred to as basal plane, (001) or (0001), single crystals. Interestingly, the available data suggest that the variation of IEPs is comparable to the range of IEPs encountered for particles, although single crystals should be much better defined in terms of surface structure. One explanation for the range of IEPs might be the obvious danger of contaminating the small surface areas of single crystal samples while exposing them to comparatively large solution reservoirs. Literature suggests that factors like origin of the sample, sample treatment or the method of investigation all have an influence on the surfaces and it is difficult to clearly separate the respective, individual effects. In the present study, we investigate cause-effect relationships to better understand the individual effects. The reference IEP of our samples is between 4 and 4.5. High temperature treatment tends to decrease the IEP of sapphire-c as does UV treatment. Increasing the initial miscut (i.e. the divergence from the expected orientation of the crystal) tends to increase the IEP as does plasma cleaning, which can be understood assuming that the surfaces have become less hydrophobic due to the presence of more and/or larger steps with increasing miscut or due to amorphisation of the surface caused by plasma cleaning. Pre-treatment at very high pH caused an increase in the IEP. Surface treatments that led to IEPs different from the stable value of reference samples typically resulted in surfaces that were strongly affected by subsequent exposure to water. The streaming potential data appear to relax to the reference sample behavior after a period of time of water exposure. Combination of the zeta potential measurements with AFM investigations support the idea that atomically smooth surfaces exhibit lower IEPs, while rougher surfaces (roughness on the order of nanometers) result in higher IEPs compared to reference samples. Two supplementary investigations resulted in either surprising or ambiguous results. On very rough surfaces (roughness on the order of micrometers) the IEP lowered compared to the reference sample with nanometer-scale roughness and transient behavior of the rough surfaces was observed. Furthermore, differences in the IEP as obtained from streaming potential and static colloid adhesion measurements may suggest that hydrodynamics play a role in streaming potential experiments. We finally relate surface diffraction data from previous studies to possible interpretations of our electroldnetic data to corroborate the presence of a water film that can explain the low IEP. Calculations show that the surface diffraction data are in line with the presence of a water film, however, they do not allow to unambiguously resolve critical features of this film which might explain the observed surface chemical characteristics like the dangling OH-bond reported in sum frequency generation studies. A broad literature review on properties of related surfaces shows that the presence of such water films could in many cases affect the interfacial properties. Persistence or not of the water film can be crucial. The presence of the water film can in principle affect important processes like ice-nucleation, wetting behavior, electric charging, etc. (C) 2017 Elsevier B.V. All rights reserved.
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| 31. |
- Martini, M. I., et al.
(författare)
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Sex Differences in Mental Health Problems and Psychiatric Hospitalization in Autistic Young Adults
- 2022
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Ingår i: Jama Psychiatry. - : American Medical Association (AMA). - 2168-622X .- 2168-6238. ; 79:12, s. 1188-1198
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Psychiatric disorders are common among autistic children and adults. Little is known about sex differences in psychiatric disorders and hospitalization in early adulthood. OBJECTIVE To examine sex differences in psychiatric diagnoses and hospitalizations in autistic compared with nonautistic young adults. DESIGN, SETTING, AND PARTICIPANTS This population-based cohort study assessed all individuals born in Sweden between 1985 and 1997. A total of 1 335 753 individuals, including 20 841 autistic individuals (7129 [34.2%] female individuals), were followed up from age 16 through 24 years between 2001 and 2013. Analysis took place between June 2021 and August 2022. EXPOSURES Autism was defined as having received at least 1 clinical diagnosis of autism based on the International Classification of Diseases. MAIN OUTCOMES AND MEASURES The cumulative incidence of 11 psychiatric diagnoses up until age 25 years was estimated, and birth year-standardized risk difference was used to compare autistic female and male individuals directly. Sex-specific birth year-adjusted hazard ratios (HRs) with 95% CIs were calculated using Cox regression. Analyses were repeated for inpatient diagnoses to assess psychiatric hospitalization. RESULTS Of 1 335 753 individuals included in this study, 650 314 (48.7%) were assigned female at birth. Autism was clinically diagnosed in 20 841 individuals (1.6%; 7129 [34.2%] female) with a mean (SD) age of 16.1 (5.1) years (17.0 [4.8] years in female individuals and 15.7 [5.2] years in male individuals) for the first recorded autism diagnosis. For most disorders, autistic female individuals were at higher risk for psychiatric diagnoses and hospitalizations. By age 25 years, 77 of 100 autistic female individuals and 62 of 100 autistic male individuals received at least 1 psychiatric diagnosis. Statistically significant standardized risk differences were observed between autistic female and male individuals for any psychiatric disorder (-0.18; 95% CI, -0.26 to -0.10) and specifically for anxiety, depressive, and sleep disorders. Risk differences were larger among autistic than nonautistic individuals. Compared with nonautistic same-sex individuals, autistic female individuals (HR range [95% CI], 3.17 [2.50-4.04.]-20.78 [18.48-23.37]) and male individuals (HR range [95% CI], 2.98 [2.75-3.23]-18.52 [17.07-20.08]) were both at increased risk for all psychiatric diagnoses. Any psychiatric hospitalization was statistically significantly more common in autistic female individuals (32 of 100) compared with autistic male individuals (19 of 100). However, both autistic female and male individuals had a higher relative risk for psychiatric hospitalization compared with nonautistic female and male individuals for all disorders (female individuals: HR range [95% CI], 5.55 [4.63-6.66]-26.30 [21.50-32.16]; male individuals: HR range [95% CI], 3.79 [3.22-4.45]-29.36 [24.04-35.87]). CONCLUSIONS AND RELEVANCE These findings highlight the need for profound mental health services among autistic young adults. Autistic female individuals, who experience more psychiatric difficulties at different levels of care, require increased clinical surveillance and support.
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| 35. |
- Nordberg, P, et al.
(författare)
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The implementation of a dual dispatch system in out-of--hospital cardiac arrest is associated withimproved short and long term survival
- 2014
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Ingår i: European Heart Journal. - : SAGE Publications. - 2048-8726 .- 2048-8734. ; 3:4, s. 293-303
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To determine the impact of a dual dispatch system, using fire fighters as first responders, in out-of-hospital cardiac arrest (OHCA) on short (30 days) and long term (three years) survival, and, to investigate the potential differences regarding in-hospital factors and interventions between the patient groups, such as the use of therapeutic hypothermia and cardiac catheterization. METHODS AND RESULTS: OHCAs from 2004 (historical controls) and 2006-2009 (intervention period) were included. During the intervention period, fire fighters equipped with automated external defibrillators (AEDs) were dispatched in suspected OHCA. Logistic regression analyses of outcome data included: the intervention with dual dispatch, sex, age, location, aetiology, witnessed status, bystander-cardiopulmonary resuscitation, first rhythm and therapeutic hypothermia. In total, 2581 OHCAs were included (historical controls n=620, intervention period n=1961). Fire fighters initiated cardiopulmonary resuscitation and connected an AED before emergency medical services' arrival in 41% of the cases. The median time from dispatch to arrival of first responder or emergency medical services shortened from 7.7 in the control period to 6.7 min in the intervention period (p<0.001). The 30-day survival improved from 3.9% to 7.6% (p=0.001), adjusted odds ratio 2.8 (confidence interval 1.6-4.9). Survival to three years increased from 2.4% to 6.5% (p<0.001), adjusted odds ratio 3.8 (confidence interval 1.9-7.6). In the logistic regression analysis including in-hospital factors we found no outcome benefit of therapeutic hypothermia. CONCLUSIONS: The implementation of a dual dispatch system using fire fighters in OHCA was associated with increased 30-day and three-year survival. No major differences in the in-hospital treatment were seen between the studied patient groups.
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| 39. |
- Rosenqvist, L., et al.
(författare)
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3D Modeling of Geomagnetically Induced Currents in Sweden-Validation and Extreme Event Analysis
- 2022
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Ingår i: Space Weather. - : American Geophysical Union (AGU). - 1542-7390. ; 20:3
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Tidskriftsartikel (refereegranskat)abstract
- Rosenqvist and Hall (2019), developed a proof-of-concept modeling capability that incorporates a detailed 3D structure of Earth's electrical conductivity in a geomagnetically induced current estimation procedure (GIC-SMAP). The model was verified based on GIC measurements in northern Sweden. The study showed that southern Sweden is exposed to stronger electric fields due to a combined effect of low crustal conductivity and the influence of the surrounding coast. This study aims at further verifying the model in this region. GIC measurements on a power line at the west coast of southern Sweden are utilized. The location of the transmission line was selected to include coast effects at the ocean-land interface to investigate the importance of using 3D induction modeling methods. The model is used to quantify the hazard of severe GICs in this particular transmission line by using historic recordings of strong geomagnetic disturbances. To quantify a worst-case scenario GICs are calculated from modeled magnetic disturbances by the Space Weather Modeling Framework based on estimates for an idealized extreme interplanetary coronal mass ejection. The observed and estimated GIC based on the 3D GIC-SMAP procedure in the transmission line in southern Sweden are in good agreement. In contrast, 1D methods underestimate GICs by about 50%. The estimated GICs in the studied transmission line exceed 100 A for one of 14 historical geomagnetic storm intervals. The peak GIC during the sudden impulse phase of a "perfect" storm exceeds 300 A but depends on the locality of the station as the interplanetary magnetic cloud hits Earth.
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| 40. |
- Rosenqvist, L., et al.
(författare)
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3D Modeling of Geomagnetically Induced Currents in Sweden—Validation and Extreme Event Analysis
- 2022
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Ingår i: Space Weather. - : John Wiley & Sons. - 1542-7390. ; 20:3
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Tidskriftsartikel (refereegranskat)abstract
- Rosenqvist and Hall (2019), https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018SW002084 developed a proof-of-concept modeling capability that incorporates a detailed 3D structure of Earth's electrical conductivity in a geomagnetically induced current estimation procedure (GIC-SMAP). The model was verified based on GIC measurements in northern Sweden. The study showed that southern Sweden is exposed to stronger electric fields due to a combined effect of low crustal conductivity and the influence of the surrounding coast. This study aims at further verifying the model in this region. GIC measurements on a power line at the west coast of southern Sweden are utilized. The location of the transmission line was selected to include coast effects at the ocean-land interface to investigate the importance of using 3D induction modeling methods. The model is used to quantify the hazard of severe GICs in this particular transmission line by using historic recordings of strong geomagnetic disturbances. To quantify a worst-case scenario GICs are calculated from modeled magnetic disturbances by the Space Weather Modeling Framework based on estimates for an idealized extreme interplanetary coronal mass ejection. The observed and estimated GIC based on the 3D GIC-SMAP procedure in the transmission line in southern Sweden are in good agreement. In contrast, 1D methods underestimate GICs by about 50%. The estimated GICs in the studied transmission line exceed 100 A for one of 14 historical geomagnetic storm intervals. The peak GIC during the sudden impulse phase of a “perfect” storm exceeds 300 A but depends on the locality of the station as the interplanetary magnetic cloud hits Earth.
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| 44. |
- Schillings, Audrey, et al.
(författare)
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Distribution and Occurrence Frequency of dB/dt Spikes During Magnetic Storms 1980–2020
- 2022
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Ingår i: Space Weather. - : John Wiley & Sons. - 1542-7390. ; 20:5
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Tidskriftsartikel (refereegranskat)abstract
- The physical magnetospheric cause for geomagnetically induced currents (GICs) are rapid time-varying magnetic fields (dB/dt), which occur mainly during magnetic substorms and storms. When, where and why exactly such rapid dB/dt may occur is insufficiently understood. We investigated all storms since 1980 and analyzed the negative and positive dB/dt spikes (>|500| nT/min) in the north and east component using a worldwide coverage (SuperMAG). Our analysis confirmed the existence of two dB/dt spikes "hotspots" located in the pre-midnight and in the morning magnetic local time sector, independently of the geographic location of the stations. The associated physical phenomena are probably substorm current wedge onsets and westward traveling surges (WTS) in the evening sector, and wave- or vortex-like current flows in the morning sector known as Omega bands. We observed a spatiotemporal evolution of the negative northern dB/dt spikes. The spikes initially occur in the pre-midnight sector, and then develop in time toward the morning sector. This spatiotemporal sequence is correlated with bursts in the AE index, and can be repeated several times throughout a storm. Finally, we investigated the peak value of Dst and AE during the storm period in comparison with the dB/dt spike occurrence frequency, we did not find any correlation. This result implies that a moderate storm with many spikes can be as (or more) dangerous for ground-based infrastructures than a major storm with fewer dB/dt spikes. Our findings regarding the physical causes and characteristics of dB/dt spikes may help to improve the GIC forecast for the affected regions.
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| 47. |
- Suarez, Carolina, et al.
(författare)
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Biofilm colonization and succession in a full-scale partial nitritation-anammox moving bed biofilm reactor
- 2024
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Ingår i: Microbiome. - 2049-2618. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Partial nitritation-anammox (PNA) is a biological nitrogen removal process commonly used in wastewater treatment plants for the treatment of warm and nitrogen-rich sludge liquor from anaerobic digestion, often referred to as sidestream wastewater. In these systems, biofilms are frequently used to retain biomass with aerobic ammonia-oxidizing bacteria (AOB) and anammox bacteria, which together convert ammonium to nitrogen gas. Little is known about how these biofilm communities develop, and whether knowledge about the assembly of biofilms in natural communities can be applied to PNA biofilms.RESULTS: We followed the start-up of a full-scale PNA moving bed biofilm reactor for 175 days using shotgun metagenomics. Environmental filtering likely restricted initial biofilm colonization, resulting in low phylogenetic diversity, with the initial microbial community comprised mainly of Proteobacteria. Facilitative priority effects allowed further biofilm colonization, with the growth of initial aerobic colonizers promoting the arrival and growth of anaerobic taxa like methanogens and anammox bacteria. Among the early colonizers were known 'oligotrophic' ammonia oxidizers including comammox Nitrospira and Nitrosomonas cluster 6a AOB. Increasing the nitrogen load in the bioreactor allowed colonization by 'copiotrophic' Nitrosomonas cluster 7 AOB and resulted in the exclusion of the initial ammonia- and nitrite oxidizers.CONCLUSIONS: We show that complex dynamic processes occur in PNA microbial communities before a stable bioreactor process is achieved. The results of this study not only contribute to our knowledge about biofilm assembly and PNA bioreactor start-up but could also help guide strategies for the successful implementation of PNA bioreactors. Video Abstract.
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