| 1. |
- Brehm, Nicolas, et al.
(författare)
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Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings
- 2021
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 14:1, s. 10-15
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Tidskriftsartikel (refereegranskat)abstract
- The Sun provides the principal energy input into the Earth system and solar variability represents a significant external climate forcing. Although observations of solar activity (sunspots) cover only the last about 400 years, radionuclides produced by cosmic rays and stored in tree rings or ice cores serve as proxies for solar activity extending back thousands of years. However, the presence of weather-induced noise or low temporal resolution of long, precisely dated records hampers cosmogenic nuclide-based studies of short-term solar variability such as the 11-yr Schwabe cycle. Here we present a continuous, annually resolved atmospheric 14C concentration (fractionation-corrected ratio of 14CO2 to CO2) record reconstructed from absolutely dated tree rings covering nearly all of the last millennium (ad 969–1933). The high-resolution and precision 14C record reveals the presence of the Schwabe cycle over the entire time range. The record confirms the ad 993 solar energetic particle event and reveals two new candidates (ad 1052 and ad 1279), indicating that strong solar events that might be harmful to modern electronic systems probably occur more frequently than previously thought. In addition to showing decadal-scale solar variability over the last millennium, the high-temporal-resolution record of atmospheric radiocarbon also provides a useful benchmark for making radiocarbon dating more accurate over this interval.
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| 2. |
- Brehm, Nicolas, et al.
(författare)
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Tree-rings reveal two strong solar proton events in 7176 and 5259 BCE
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- The Sun sporadically produces eruptive events leading to intense fluxes of solar energetic particles (SEPs) that dramatically disrupt the near-Earth radiation environment. Such events have been directly studied for the last decades but little is known about the occurrence and magnitude of rare, extreme SEP events. Presently, a few events that produced measurable signals in cosmogenic radionuclides such as 14C, 10Be and 36Cl have been found. Analyzing annual 14C concentrations in tree-rings from Switzerland, Germany, Ireland, Russia, and the USA we discovered two spikes in atmospheric 14C occurring in 7176 and 5259 BCE. The ~2% increases of atmospheric 14C recorded for both events exceed all previously known 14C peaks but after correction for the geomagnetic field, they are comparable to the largest event of this type discovered so far at 775 CE. These strong events serve as accurate time markers for the synchronization with floating tree-ring and ice core records and provide critical information on the previous occurrence of extreme solar events which may threaten modern infrastructure.
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| 3. |
- Nordanstig, Annika, 1974, et al.
(författare)
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EndoVAscular treatment and ThRombolysis for Ischemic Stroke Patients (EVA-TRISP) registry: basis and methodology of a pan-European prospective ischaemic stroke revascularisation treatment registry.
- 2021
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- The Thrombolysis in Ischemic Stroke Patients (TRISP) collaboration was a concerted effort initiated in 2010 with the purpose to address relevant research questions about the effectiveness and safety of intravenous thrombolysis (IVT). The collaboration also aims to prospectively collect data on patients undergoing endovascular treatment (EVT) and hence the name of the collaboration was changed from TRISP to EVA-TRISP. The methodology of the former TRISP registry for patients treated with IVT has already been published. This paper focuses on describing the EVT part of the registry.All centres committed to collecting predefined variables on consecutive patients prospectively. We aim for accuracy and completeness of the data and to adapt local databases to investigate novel research questions. Herein, we introduce the methodology of a recently constructed academic investigator-initiated open collaboration EVT registry built as an extension of an existing IVT registry in patients with acute ischaemic stroke (AIS).Currently, the EVA-TRISP network includes 20 stroke centres with considerable expertise in EVT and maintenance of high-quality hospital-based registries. Following several successful randomised controlled trials (RCTs), many important clinical questions remain unanswered in the (EVT) field and some of them will unlikely be investigated in future RCTs. Prospective registries with high-quality data on EVT-treated patients may help answering some of these unanswered issues, especially on safety and efficacy of EVT in specific patient subgroups.This collaborative effort aims at addressing clinically important questions on safety and efficacy of EVT in conditions not covered by RCTs. The TRISP registry generated substantial novel data supporting stroke physicians in their daily decision making considering IVT candidate patients. While providing observational data on EVT in daily clinical practice, our future findings may likewise be hypothesis generating for future research as well as for quality improvement (on EVT). The collaboration welcomes participation of further centres willing to fulfill the commitment and the outlined requirements.
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| 4. |
- Psychogios, Marios, et al.
(författare)
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European Stroke Organisation guidelines on treatment of patients with intracranial atherosclerotic disease
- 2022
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Ingår i: European Stroke Journal. - : SAGE Publications. - 2396-9881 .- 2396-9873.
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present European Stroke Organisation guideline is to provide clinically useful evidence-basedrecommendations on the management of patients with intracranial atherosclerotic disease (ICAD). The guidelines wereprepared following the Standard Operational Procedure of the European Stroke Organisation guidelines and accordingto GRADE methodology. ICAD represents a major cause of ischemic stroke worldwide, and patients affected by thiscondition are exposed to a high risk for future strokes and other major cardiovascular events, despite best medicaltherapy available. We identified 11 relevant clinical problems affecting ICAD patients and formulated the correspondingPopulation Intervention Comparator Outcomes (PICO) questions. The first two questions refer to the asymptomaticstage of the disease, which is being increasingly detected thanks to the routine use of noninvasive vascular imaging. Wewere not able to provide evidence-based recommendations regarding the optimal detection strategy and management ofasymptomatic ICAD, and further research in the field is encouraged as subclinical ICAD may represent a big opportunityto improve primary stroke prevention. The second block of PICOs (3–5) is dedicated to the management of acutelarge vessel occlusion (LVO) ischemic stroke caused by ICAD, a clinical presentation of this disease that is becomingincreasingly relevant and problematic, since it is associated with more refractory endovascular reperfusion procedures.An operational definition of probable ICAD-related LVO is proposed in the guideline. Despite the challenging context,no dedicated randomized clinical trials (RCTs) were identified, and therefore the guideline can only provide withsuggestions derived from observational studies and our expert consensus, such as the escalated use of glycoproteinIIb-IIIa inhibitors and angioplasty/stenting in cases of refractory thrombectomies due to underlying ICAD. The last blockof PICOs is devoted to the secondary prevention of patients with symptomatic ICAD. Moderate-level evidence wasfound to recommend against the use of oral anticoagulation as preferred antithrombotic drug, in favor of antiplatelets.Low-level evidence based our recommendation in favor of double antiplatelet as the antithrombotic treatment of choicein symptomatic ICAD patients, which we suggest to maintain during 90days as per our expert consensus. Endovasculartherapy with intracranial angioplasty and or stenting is not recommended as a treatment of first choice in high-gradesymptomatic ICAD (moderate-level evidence). Regarding neurosurgical interventions, the available evidence does notsupport their use as front line therapies in patients with high-grade ICAD. There is not enough evidence as to provideany specific recommendation regarding the use of remote ischemic conditioning in ICAD patients, and further RCTsare needed to shed light on the utility of this promising therapy. Finally, we dedicate the last PICO to the importanceof aggressive vascular risk factor management in ICAD, although the evidence derived from RCTs specifically addressingthis question is still scarce
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