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- Nguyen, Thanh N, et al.
(författare)
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Global Impact of the COVID-19 Pandemic on Stroke Volumes and Cerebrovascular Events: A 1-Year Follow-up.
- 2023
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Ingår i: Neurology. - 1526-632X. ; 100:4
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Tidskriftsartikel (refereegranskat)abstract
- Declines in stroke admission, IV thrombolysis (IVT), and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the effect of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), IVT, and mechanical thrombectomy over a 1-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020).We conducted a longitudinal retrospective study across 6 continents, 56 countries, and 275 stroke centers. We collected volume data for COVID-19 admissions and 4 stroke metrics: ischemic stroke admissions, ICH admissions, IVT treatments, and mechanical thrombectomy procedures. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases.There were 148,895 stroke admissions in the 1 year immediately before compared with 138,453 admissions during the 1-year pandemic, representing a 7% decline (95% CI [95% CI 7.1-6.9]; p < 0.0001). ICH volumes declined from 29,585 to 28,156 (4.8% [5.1-4.6]; p < 0.0001) and IVT volume from 24,584 to 23,077 (6.1% [6.4-5.8]; p < 0.0001). Larger declines were observed at high-volume compared with low-volume centers (all p < 0.0001). There was no significant change in mechanical thrombectomy volumes (0.7% [0.6-0.9]; p = 0.49). Stroke was diagnosed in 1.3% [1.31-1.38] of 406,792 COVID-19 hospitalizations. SARS-CoV-2 infection was present in 2.9% ([2.82-2.97], 5,656/195,539) of all stroke hospitalizations.There was a global decline and shift to lower-volume centers of stroke admission volumes, ICH volumes, and IVT volumes during the 1st year of the COVID-19 pandemic compared with the prior year. Mechanical thrombectomy volumes were preserved. These results suggest preservation in the stroke care of higher severity of disease through the first pandemic year.This study is registered under NCT04934020.
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- Hernaiz, M., et al.
(författare)
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The contact angle of nanofluids as thermophysical property
- 2019
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797. ; 547, s. 393-406
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Tidskriftsartikel (refereegranskat)abstract
- Droplet volume and temperature affect contact angle significantly. Phase change heat transfer processes of nanofluids – suspensions containing nanometre-sized particles – can only be modelled properly by understanding these effects. The approach proposed here considers the limiting contact angle of a droplet asymptotically approaching zero-volume as a thermophysical property to characterise nanofluids positioned on a certain substrate under a certain atmosphere. Graphene oxide, alumina, and gold nanoparticles are suspended in deionised water. Within the framework of a round robin test carried out by nine independent European institutes the contact angle of these suspensions on a stainless steel solid substrate is measured with high accuracy. No dependence of nanofluids contact angle of sessile droplets on the measurement device is found. However, the measurements reveal clear differences of the contact angle of nanofluids compared to the pure base fluid. Physically founded correlations of the contact angle in dependency of droplet temperature and volume are obtained from the data. Extrapolating these functions to zero droplet volume delivers the searched limiting contact angle depending only on the temperature. It is for the first time, that this specific parameter, is understood as a characteristic material property of nanofluid droplets placed on a certain substrate under a certain atmosphere. Together with the surface tension it provides the foundation of proper modelling phase change heat transfer processes of nanofluids.
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- Cobianchi, M., et al.
(författare)
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Effects of oceanic circulation and volcanic ash-fall on calcite dissolution in bathyal sediments from the SW Pacific Ocean over the last 550 ka
- 2015
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 429, s. 72-82
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Tidskriftsartikel (refereegranskat)abstract
- The effects on calcite dissolution of both oceanic circulation and volcanic ash-fall were evaluated in lower bathyal sediments over the last 550 ka record from core MD 97-2114, recovered on the northern slope (depth of 1936 m, in the Pacific Deep Water, PDW) of the Chatham Rise (east of New Zealand, SW Pacific Ocean). This area has been impacted by changes in glacial/interglacial circulation and ocean chemistry as well as by the explosive volcanic activity of the Taupo Volcanic Zone. Several micro-paleontological dissolution proxies, based on planktonic foraminifera and calcareous nannofossils, were analysed in order to evaluate the calcite dissolution of the deep-sea sediments. These were compared with a couple of proxies of primary productivity (benthic foraminiferal epifaunal/infaunal ratio and delta C-13(benthic) (foraminifera)) and the abundance of volcanic glass. The dissolution proxy data from MD 97-2114 were compared with two nearby ODP sites, ODP 1123 (3290 m deep, bathed by the lower Circumpolar Deep Water, LCDW) and ODP 1125 (1365 m deep, bathed by the Antarctic Intermediate Water, AAIW). The results suggest: (1) the calcite dissolution/preservation cycles at all three core sites show Glacial-Interglacial (G-I) periodicities that match the previously described "Pacific-style" CaCO3 cycles; (2) several short-term dissolution events do not follow this general scheme and occur following tephra deposition. The dissolution related to the tephra deposition seems to have mostly affected calcareous nannofossils, thus we hypothesise that the ash-fall induced a temporary reduction of the surface water pH (below 7.8), which affected the coccolithophores that inhabit the surface waters. (3) Other short-term dissolution events (1000 years) are unrelated to tephra deposition and are possibly driven by the slowing of deep-sea circulation and a reduced Deep Western Boundary Current (DWBC). This lead to the dominance of older, more corrosive Pacific Deep Water (POW) flowing in to the region, resulting in coeval dissolution episodes at all three core sites (depth range from 1365 to 3290 m).
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