5 results
A feedback model of the edge tone, using the adjoint Orr–Sommerfeld equation
- Péter Tamás Nagy, András Szabó, György Paál
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- Journal:
- Journal of Fluid Mechanics / Volume 915 / 25 May 2021
- Published online by Cambridge University Press:
- 09 March 2021, A13
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- Article
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The description of the feedback mechanism is one of the crucial points in the understanding of self-sustained flow oscillations, such as the edge tone or the cavity tone. In this paper a new model for the edge tone, using linear adjoint modes is proposed for low speeds, when acoustic effects are negligible. The two crucial points of the model are (i) a new relationship between the jet oscillation and the generated vortex at the edge tip and (ii) a new model for the effect of the generated vortex on the oscillation. The frequency corresponding to the optimum open-loop gain of the feedback mechanism was compared with experimental data and good agreement was found.
11 - Trauma and Hypothermia
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- By Peter Paal, Head of the Department of Anaesthesiology and Intensive Care Medicine, Hospitallers Brother Hospital, Salzburg, Austria, Bernd Wallner, Resident, Department of Anesthesiology and Critical Care Medicine, Innsbruck University Hospital, Austria, Hermann Brugger, Head of the Institute of Mountain Emergency Medicine, EURAC Research
- Edited by Sylweriusz Kosiński, Tomasz Darocha, Jerzy Sadowski, Rafał Drwiła
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- Book:
- Hypothermia: Clinical Aspects Of Body Cooling
- Published by:
- Jagiellonian University Press
- Published online:
- 03 January 2018
- Print publication:
- 01 December 2016, pp 89-96
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Summary
In multiple trauma patients accidental hypothermia (i.e. core temperature < 35°C) is more frequent in winter but must be expected at all seasons of the year, even in regions with moderate climate [1]. The incidence of multiple trauma patients admitted with accidental hypothermia is underestimated, but may exceed 30% [1]. The low reporting rate of accidental hypothermia is partly owed to the lack of reliable thermometers for cold environment. The low awareness for accidental hypothermia leads to insufficient insulation and rewarming measures in the pre- and in-hospital setting.
Accidental hypothermia in multiple trauma is an independent risk factor for increased mortality. In a state-wide trauma registry in Pennsylvania (n = 38,520) mortality of multiple trauma patients increased exponentially with the degree of accidental hypothermia at hospital admission. With a core temperature < 32°C at hospital admission mortality approached 50% (Figure 1) [2]. Multiple trauma patients are prone to accidental hypothermia because central and peripheral thermoregulation are inhibited. This may be due to haemorrhage (i.e. underperfusion of thermoregulation centres in the hypothalamus) and reduced or abolished shivering. Vasodilation as a result of peripheral hypoxia with concomitant metabolic acidosis or analgosedation (possibly less pronounced with ketamine) [3, 4].
Keeping the traumatized patient normothermic is of utmost importance. Patients should be thoroughly and timely insulated, cold and excessive infusions avoided, considerate analgesia and sedation provided with the understanding that they may accelerate cooling. In a cold environment changing clothes is not required as long as patients are insulated water-vapour-tight to avoid heat loss through evaporation [5, 6]. Implementation of the available knowledge and equipment is recommended [7]. Rewarming should be commenced as soon and as aggressively as possible. Even though in regular ambulances and transport times of < 1 hour prehospital rewarming may not be feasible, further cooling of the warm body core by the cold body shell can be limited. In prolonged transports with the availability of forced warm air or heating body pads rewarming (1–2°C/h) may be achieved [8].
12 - Prehospital Management of Avalanche Victims
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- By Hermann Brugger, Head of the Institute of Mountain Emergency Medicine, EURAC Research, Giacomo Strapazzon, EURAC Institute of Mountain Emergency Medicine, Bozen, Italy, Peter Paal, Head of the Department of Anaesthesiology and Intensive Care Medicine, Hospitallers Brother Hospital, Salzburg, Austria
- Edited by Sylweriusz Kosiński, Tomasz Darocha, Jerzy Sadowski, Rafał Drwiła
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- Book:
- Hypothermia: Clinical Aspects Of Body Cooling
- Published by:
- Jagiellonian University Press
- Published online:
- 03 January 2018
- Print publication:
- 01 December 2016, pp 97-114
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Summary
This chapter is based on following publications:
• Brugger H., Durrer B., Elsensohn F., Paal P., Strapazzon G., Winterberger E., Zafren K., Boyd J. Resuscitation of avalanche victims: Evidence- -based guidelines of the international commission for mountain emergency medicine (ICAR MEDCOM): intended for physicians and other advanced life support personnel. Resuscitation 2013; 84: 539–546.
• Brugger H., Paal P., Boyd J. Prehospital resuscitation of the buried avalanche vict im. High Altitude Medicine & Biology 2011; 12: 199–205.
• Truhlář A., Deakin C.D., Soar J., Khalifa G.E., Alfonzo A., Bierens J.J., Brattebo G., Brugger H., Dunning J., Hunyadi-Anticevic S., Koster R.W., Lockey D.J., Lott C., Paal P., Perkins G.D., Sandroni C., Thies K.C., Zideman D.A., Nolan J.P. European Resuscitation Council Guidelines for Resuscitation 2015: Section 4. Cardiac arrest in special circumstances. Resuscitation 2015; 95: 148–201.
Summary
In North America and Europe, approximately 165 people die of avalanches per year. Four factors are decisive for survival: grade and duration of burial, presence of a free airway, and severity of trauma. The overall mortality rate is 23%, but 52.4% in completely buried (i.e. head below the snow) victims in contrast to 4.2% in partially buried (i.e. head free) victims. Survival in completely buried victims drops to 30% within the first 35 minutes due to trauma and asphyxia. Thereafter survival decreases more gradually and victims slowly succumb to a trias of hypoxia, hypercapnia and hypothermia if they are able to breath. In the absence of fatal injuries, rescue strategies depend primarily on trauma, duration of burial, the victim's core temperature and the patency of the airway. In 2015, the European Resuscitation Council proposed an algorithm for the management of avalanche victims. With a burial time < 60 minutes (or core temperature ≥ 30°C) rapid extrication and prevention of asphyxia is essential, with adequate airway management and cardiopulmonary resuscitation. With a burial time > 60 minutes or core temperature < 30°C tackling severe hypothermia should be expected. Gentle extrication and continuous core temperature and cardiac monitoring are recommended. Pulseless victims with a patent airway, duration of burial > 60 minutes or a core temperature < 30°C should receive continuous or intermittent cardiopulmonary resuscitation and be transported to a hospital with extracorporeal rewarming facilities.
18 - Problems and Pitfalls of Qualification for Extracorporeal Treatment of Patients in Severe Hypothermia
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- By Anna Jarosz, “Heat for Life” Foundation, Cracow, Poland, Sylweriusz Kosiński, Department of Anesthesiology and Intensive Care, Pulmonary Hospital, Zakopane, Poland, Tomasz Darocha, “Heat for Life” Foundation, Cracow, Poland, Hubert Hymczak, Tatra Mountain Rescue Service, Zakopane, Poland, Peter Paal, Head of the Department of Anaesthesiology and Intensive Care Medicine, Hospitallers Brother Hospital, Salzburg, Austria, Rafał Drwiła, Department of Anaesthesiology and Intensive Care, John Paul II Hospital, Cracow, Poland
- Edited by Sylweriusz Kosiński, Tomasz Darocha, Jerzy Sadowski, Rafał Drwiła
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- Book:
- Hypothermia: Clinical Aspects Of Body Cooling
- Published by:
- Jagiellonian University Press
- Published online:
- 03 January 2018
- Print publication:
- 01 December 2016, pp 161-168
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Summary
If indications for extracorporeal rewarming in hypothermia are clearly defined, the problems one might encounter in practice have not been, as yet, delineated. Isolated reports on “qualification pitfalls” appear in certain case studies, but majority of these constitute only relative contraindications. In patients with instability of cardiovascular system, and cardiac arrest in particular, decision to qualify for extracorporeal rewarming must be immediate. At the same time, diagnostic possibilities are significantly limited (incoming reports from emergency medical teams or mountain rescue services, patients undergoing resuscitation or extremely unstable). In such instances not qualification, but denial of extracorporeal treatment may present the greatest challenge on both clinical as well as ethical planes.
The compilation of problems and pitfalls experienced during qualification procedure is based upon several months of work of Severe Hypothermia Treatment Centre coordinators in Kraków. It is until now the only centre specialising in extracorporeal rewarming in Poland, and the only one operating according to proprietary, uniform algorithm. This has allowed to observe recurrence of certain conditions, assess their importance and draw appropriate conclusions. ECMO therapy carries a risk of grave complications, but majority of these can be avoided by means of proper qualification procedure and avoidance of factors which affect the very treatment. As emphasised before, the problems described below constitute merely relative contraindications, and thanks to good long term outcomes of extracorporeal rewarming, they should be considered in relation to a complete disorder evaluation and discussed by the team involved in the treatment.
Thrombocytopenia and/or clinically important anaemia
These disorders are present in patients belonging to so called “underclass”, but also in the elderly, neglected and malnutrition stricken victims of “urban hypothermia.” The values of haemoglobin seen in our patients reached even 3.6 mg/dL and thrombocyte count 18,000/mL. It should be stressed that even such low parameters do not constitute a contraindication for extracorporeal rewarming, yet require intervention.
DESIREE as a new tool for interstellar ion chemistry
- Henning T. Schmidt, Henrik A.B. Johansson, Richard D. Thomas, Wolf D. Geppert, Nicole Haag, Peter Reinhed, Stefan Rosén, Mats Larsson, Håkan Danared, K.-G. Rensfelt, Leif Liljeby, Lars Bagge, Mikael Björkhage, Mikael Blom, Patrik Löfgren, Anders Källberg, Ansgar Simonsson, Andras Paál, Henning Zettergren, Henrik Cederquist
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- Journal:
- International Journal of Astrobiology / Volume 7 / Issue 3-4 / October 2008
- Published online by Cambridge University Press:
- 12 August 2008, pp. 205-208
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A novel cryogenic electrostatic storage device consisting of two ion-beam storage rings with a common straight section for studies of interactions between oppositely charged ions at low and well-defined relative velocities is under construction at Stockholm University. Here we consider the prospect of using this new tool to measure cross-sections and rate coefficients for mutual neutralization reactions of importance in interstellar ion chemistry in general and specifically in cosmic pre-biotic ion chemistry.