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- Kereszturi, Gabor, et al.
(author)
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Porosity, strength, and alteration - Towards a new volcano stability assessment tool using VNIR-SWIR reflectance spectroscopy
- 2023
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In: Earth and Planetary Science Letters. - : Elsevier. - 0012-821X .- 1385-013X. ; 602
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Journal article (peer-reviewed)abstract
- Volcano slope stability analysis is a critical component of volcanic hazard assessments and monitoring. However, traditional methods for assessing rock strength require physical samples of rock which may be difficult to obtain or characterize in bulk. Here, visible to shortwave infrared (350-2500 nm; VNIR-SWIR) reflected light spectroscopy on laboratory-tested rock samples from Ruapehu, Ohakuri, Whakaari, and Banks Peninsula (New Zealand), Merapi (Indonesia), Chaos Crags (USA), Styrian Basin (Austria) and La Soufriere de Guadeloupe (Eastern Caribbean) volcanoes was used to design a novel rapid chemometric-based method to estimate uniaxial compressive strength (UCS) and porosity. Our Partial Least Squares Regression models return moderate accuracies for both UCS and porosity, with R2 of 0.43-0.49 and Mean Absolute Percentage Error (MAPE) of 0.2-0.4. When laboratory-measured porosity is included with spectral data, UCS prediction reaches an R2 of 0.82 and MAPE of 0.11. Our models highlight that the observed changes in the UCS are coupled with subtle mineralogical changes due to hydrothermal alteration at wavelengths of 360-438, 532-597, 1405-1455, 2179-2272, 2332-2386, and 2460-2490 nm. These mineralogical changes include mineral replacement, precipitation hydrothermal alteration processes which impact the strength of volcanic rocks, such as mineral replacement, precipitation, and/or silicification. Our approach highlights that spectroscopy can provide a first order assessment of rock strength and/or porosity or be used to complement laboratory porosity-based predictive models. VNIR-SWIR spectroscopy therefore provides an accurate non-destructive way of assessing rock strength and alteration mineralogy, even from remote sensing platforms. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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- Anand, K J S, et al.
(author)
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Effects of morphine analgesia in ventilated preterm neonates : primary outcomes from the NEOPAIN randomised trial
- 2004
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In: The Lancet. - 0140-6736 .- 1474-547X. ; 363:9422, s. 1673-82
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Journal article (peer-reviewed)abstract
- BACKGROUND: Opioid analgesia is commonly used during neonatal intensive care. We undertook the Neurologic Outcomes and Pre-emptive Analgesia in Neonates (NEOPAIN) trial to investigate whether pre-emptive morphine analgesia decreases the rate of a composite primary outcome of neonatal death, severe intraventricular haemorrhage (IVH), and periventricular leucomalacia (PVL) in preterm neonates.METHODS: Ventilated preterm neonates (n=898) from 16 centres were randomly assigned masked placebo (n=449) or morphine (n=449) infusions. After a loading dose (100 microg/kg), morphine infusions (23-26 weeks of gestation 10 microg kg(-1) h(-1); 27-29 weeks 20 microg kg(-1) h(-1); 30-32 weeks 30 microg kg(-1) h(-1)) were continued as long as clinically justified (maximum 14 days). Open-label morphine could be given on clinical judgment (placebo group 242/443 [54.6%], morphine group 202/446 [45.3%]). Analyses were by intention to treat.FINDINGS: Baseline variables were similar in the randomised groups. The placebo and morphine groups had similar rates of the composite outcome (105/408 [26%] vs 115/419 [27%]), neonatal death (47/449 [11%] vs 58/449 [13%]), severe IVH (46/429 [11%] vs 55/411 [13%]), and PVL (34/367 [9%] vs 27/367 [7%]). For neonates who were not given open-label morphine, rates of the composite outcome (53/225 [24%] vs 27/179 [15%], p=0.0338) and severe IVH (19/219 [9%] vs 6/189 [3%], p=0.0209) were higher in the morphine group than the placebo group. Placebo-group neonates receiving open-label morphine had worse rates of the composite outcome than those not receiving open-label morphine (78/228 [34%] vs 27/179 [15%], p<0.0001). Morphine-group neonates receiving open-label morphine were more likely to develop severe IVH (36/190 [19%] vs 19/219 [9%], p=0.0024).INTERPRETATION: Pre-emptive morphine infusions did not reduce the frequency of severe IVH, PVL, or death in ventilated preterm neonates, but intermittent boluses of open-label morphine were associated with an increased rate of the composite outcome. The morphine doses used in this study decrease clinical signs of pain but can cause significant adverse effects in ventilated preterm neonates.
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- Carbajal, Ricardo, et al.
(author)
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Pain Assessment in Ventilated and Non-Ventilated Neonates in NICUs across Europe : EUROpean Pain Audit in Neonates (EUROPAIN Survey)
- 2014
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Conference paper (peer-reviewed)abstract
- Background: Neonates undergo many painful procedures during their NICU stay. These may include tracheal intubation/ventilation, skin-breaking procedures, drainage/suctioning of body orifices or cavities. Inherent subjectivity and difficulties of neonatal pain assessment contribute to a wide variety of assessment tools and clinical practices. To date, these practices have been not studied at a large scale. OBJECTIVE: To determine current clinical practices for neonatal pain assessment in NICUs across Europe. DESIGN/METHODS: An epidemiological observational study on bedside pain assessment practices collected data for all neonates in participating NICUs until infants left the unit (discharge, death, transfer to another hospital) or for 28 days. Data collection occurred via an online database for 1 month at each NICU. All neonates up to a gestational age of 44 weeks were included. RESULTS: From October 2012 to June 2013, 243 NICUs from 18 European countries collected pain assessment data in 6680 neonates. Of these, 2142 received tracheal ventilation (ventilated) and 4538 had spontaneous breathing or non- invasive ventilation (non-ventilated). The median (IQR) gestational age of ventilated neonates [32.1 (28.1-37.4)] was less than non-ventilated neonates [36.6 (33.6-39.1), p<0.001]. Overall, 58.5% of ventilated neonates and 35.2%% of non-ventilated neonates received bedside pain assessments (p<0.001). CONCLUSIONS: Over half (58.5%) of ventilated neonates and about one third (35.2%) of non-ventilated neonates had pain assessments performed in European NICUs. Wide variations in the methods used and rates of pain assessment exist among countries
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- Carbajal, Ricardo, et al.
(author)
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Pain Assessment In Ventilated And Non-ventilated Neonates In Nicus Across Europe : European Pain Audit In Neonates (europain Survey)
- 2014
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In: Archives of Disease in Childhood. - London, United Kingdom : BMJ Publishing Group Ltd. - 0003-9888 .- 1468-2044. ; 99, s. A68-A68
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Journal article (peer-reviewed)abstract
- Background: Neonates undergo many painful procedures during their NICU stay. These may include tracheal intubation/ventilation, skin-breaking procedures, drainage/suctioning of body orifices or cavities. Inherent subjectivity and difficulties of neonatal pain assessment contribute to a wide variety of assessment tools and clinical practices. To date, these practices have been not studied at a large scale.Objective: To determine current clinical practices for neonatal pain assessment in NICUs across Europe.Methods: An epidemiological observational study on bedside pain assessment practices collected data for all neonates in participating NICUs until infants left the unit (discharge, death, transfer to another hospital) or for 28 days. Data collection occurred via an online database for 1 month at each NICU. All neonates up to a gestational age of 44 weeks were included.Results: From October 2012 to June 2013, 243 NICUs from 18 European countries collected pain assessment data in 6680 neonates. Of these, 2142 received tracheal ventilation (TV), 1496 non-invasive ventilation (NIV) and 3042 only spontaneous ventilation (SV). The median (IQR) gestational age of TV, NIV and SV neonates were 32.1 (28.1–37.4), 33.6 (31.0–36.6) and 37.9 (35.0–39.9), respectively (p < 0.001). Overall, 58.5% of TV neonates, 45.0% of NIV neonates and 30.4% of SV neonates received bedside pain assessments (p < 0.001). Fig. shows pain assessments by country.Conclusions: Over half (58.5%) of TV neonates and less than half (45.0%) of NIV neonates had pain assessments performed in European NICUs. Wide variations in the rates of pain assessment exist among countries and an important improvement seems necessary.
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| 7. |
- Carbajal, Ricardo, et al.
(author)
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Sedation And Analgesia For Neonates In Nicus Across Europe : The Europain Survey
- 2014
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In: Archives of Disease in Childhood. - London, United Kingdom : BMJ Publishing Group Ltd. - 0003-9888 .- 1468-2044. ; 99, s. A64-A64
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Journal article (peer-reviewed)abstract
- Background: Pain and stress induced by mechanical ventilation, invasive procedures, or painful diseases supports the use of sedation/analgesia (S/A) in newborns admitted to Neonatal Intensive Care Units (NICUs). To date, these practices have not been studied at a large scale.Objective: To determine current clinical practices regarding the use of S/A drugs in NICUs across Europe.Methods: This epidemiological observational study on bedside clinical practices regarding S/A collected data for all neonates in participating NICUs until the infant left the unit (discharge, death, transfer) or for up to 28 days. Data collection occurred via an online database for 1 month at each NICU. All neonates up to 44 weeks gestation were included.Results: From October 2012 to June 2013, 243 NICUs from 18 European countries collected data on 6680 eligible neonates. Of these, 2142 received tracheal ventilation (TV), 1496 non-invasive ventilation (NIV) and 3042 only spontaneous ventilation (SV). The median (IQR) gestational age of TV, NIV and SV neonates were 32.1 (28.1–37.4), 33.6 (31.0–36.6) and 37.9 (35.0–39.9), respectively (p < 0.001). Overall, more TV neonates [81.5% (n = 1746)] received S/A drugs than NIV neonates [17.8% (n = 266)] and SV neonates [9.3% (n = 282)]; p < 0.001. Fig. shows the rate of S/A use by country; table shows S/A drugs used.Conclusions: Most ventilated but few non-ventilated neonates (NIV and SV) receive S/A therapy in European NICUs. Wide variations in S/A use, drugs used, and mode of administration (continuous, bolus, or both) exist among countries.
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- Heap, Michael J., et al.
(author)
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The tensile strength of hydrothermally altered volcanic rocks
- 2022
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In: Journal of Volcanology and Geothermal Research. - : Elsevier. - 0377-0273 .- 1872-6097. ; 428
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Journal article (peer-reviewed)abstract
- The tensile strength of volcanic rocks is an important parameter for understanding and modelling a wide range of volcanic processes, and in the development of strategies designed to optimise energy production in volcanic geothermal reservoirs. However, despite the near-ubiquity of hydrothermal alteration at volcanic and geothermal systems, values of tensile strength for hydrothermally altered volcanic rocks are sparse. Here, we present an experimental study in which we measured the tensile strength of variably altered volcanic rocks. The alteration of these rocks, quantified as the weight percentage of secondary (alteration) minerals, varied from 6 to 62.8 wt%. Our data show that tensile strength decreases as a function of porosity, in agreement with previous studies, and as a function of alteration. We fit existing theoretical constitutive models to our data so that tensile strength can be estimated for a given porosity, and we provide a transformation of these models such that they are a function of alteration. However, because porosity and alteration influence each other, it is challenging to untangle their individual contributions to the measured reduction in tensile strength. Our new data and previously published data suggest that porosity exerts a first-order role on the tensile strength of volcanic rocks. Based on our data and observations, we also suggest that (1) alteration likely decreases tensile strength if associated with mineral dissolution, weak secondary minerals (such as clays), and an increase in microstructural heterogeneity and (2) alteration likely increases tensile strength if associated with pore- and crack-filling mineral precipitation. Therefore, we conclude that both alteration intensity and alteration type likely influence tensile strength. To highlight the implications of our findings, we provide discrete element method modelling which shows that, following the pressurisation of a dyke, the damage within weak hydrothermally altered host-rock is greater and more widespread than for strong hydrothermally altered host-rock. Because the rocks in volcanic and geothermal settings are likely to be altered, our results suggest that future modelling should consider the tensile strength of hydrothermally altered volcanic rocks.
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