| 1. |
- Abdo, A. A., et al.
(författare)
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FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 696:2, s. 1084-1093
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Tidskriftsartikel (refereegranskat)abstract
- The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new gamma-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E >= 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of Gamma = 1.51(-0.04)(+0.05) with an exponential cutoff at E-c = 2.9 +/- 0.1 GeV. Spectral fits with generalized cutoffs of the form e(-(E/Ec)b) require b <= 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.
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| 2. |
- Ambrosio, M, et al.
(författare)
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The MACRO detector at Gran Sasso
- 2002
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 486:3, s. 663-707
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Tidskriftsartikel (refereegranskat)abstract
- MACRO was an experiment that ran in the Laboratori Nazionali del Gran Sasso from 1988 to 2000. Its principal goal was to observe magnetic monopoles or set significantly lower experimental flux limits than had been previously available in the velocity range from about beta = 10(-4) to unity. In addition it made a variety of other observations. Examples are: setting flux limits on other so far unobserved particles such as nuclearites and lightly ionizing particles, searching for WIMP annihilations in the Earth and the Sun and for neutrino bursts from stellar collapses in or near our Galaxy, and making measurements relevant to high energy muon and neutrino astronomy and of the flux of up-going muons as a function of nadir angle showing evidence for neutrino oscillations. The apparatus consisted of three principal types of detectors: liquid scintillator counters, limited streamer tubes, and nuclear track etch detectors. In addition, over part of its area it contained a transition radiation detector. The general design philosophy emphasized redundancy and complementarity. This paper describes the technical aspects of the complete MACRO detector, its operational performance, and the techniques used to calibrate it and verify its proper operation. It supplements a previously published paper which described the first portion of the detector that was built and operated. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 3. |
- Borges, João Batista, et al.
(författare)
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Zero expiratory pressure and low oxygen concentration promote heterogeneity of regional ventilation and lung densities
- 2016
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 60:7, s. 958-968
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIt is not well known what is the main mechanism causing lung heterogeneity in healthy lungs under mechanical ventilation. We aimed to investigate the mechanisms causing heterogeneity of regional ventilation and parenchymal densities in healthy lungs under anesthesia and mechanical ventilation. MethodsIn a small animal model, synchrotron imaging was used to measure lung aeration and regional-specific ventilation (sV.). Heterogeneity of ventilation was calculated as the coefficient of variation in sV. (CVsV.). The coefficient of variation in lung densities (CVD) was calculated for all lung tissue, and within hyperinflated, normally and poorly aerated areas. Three conditions were studied: zero end-expiratory pressure (ZEEP) and FIO2 0.21; ZEEP and FIO2 1.0; PEEP 12 cmH(2)O and F(I)O(2)1.0 (Open Lung-PEEP = OLP). ResultsThe mean tissue density at OLP was lower than ZEEP-1.0 and ZEEP-0.21. There were larger subregions with low sV. and poor aeration at ZEEP-0.21 than at OLP: 12.9 9.0 vs. 0.6 +/- 0.4% in the non-dependent level, and 17.5 +/- 8.2 vs. 0.4 +/- 0.1% in the dependent one (P = 0.041). The CVsV. of the total imaged lung at PEEP 12 cmH(2)O was significantly lower than on ZEEP, regardless of FIO2, indicating more heterogeneity of ventilation during ZEEP (0.23 +/- 0.03 vs. 0.54 +/- 0.37, P = 0.049). CVD changed over the different mechanical ventilation settings (P = 0.011); predominantly, CVD increased during ZEEP. The spatial distribution of the CVD calculated for the poorly aerated density category changed with the mechanical ventilation settings, increasing in the dependent level during ZEEP. ConclusionZEEP together with low FIO2 promoted heterogeneity of ventilation and lung tissue densities, fostering a greater amount of airway closure and ventilation inhomogeneities in poorly aerated regions.
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| 4. |
- Karbing, D. S., et al.
(författare)
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Journal of Clinical Monitoring and Computing 2017 end of year summary : respiration
- 2018
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Ingår i: Journal of clinical monitoring and computing. - : Springer Science and Business Media LLC. - 1387-1307 .- 1573-2614. ; 32:2, s. 197-205
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Forskningsöversikt (refereegranskat)abstract
- This paper reviews 32 papers or commentaries published in Journal of Clinical Monitoring and Computing in 2016, within the field of respiration. Papers were published covering airway management, ventilation and respiratory rate monitoring, lung mechanics and gas exchange monitoring, in vitro monitoring of lung mechanics, CO2 monitoring, and respiratory and metabolic monitoring techniques.
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| 5. |
- Karbing, D. S., et al.
(författare)
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Journal of Clinical Monitoring and Computing 2018-2019 end of year summary : respiration
- 2020
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Ingår i: Journal of clinical monitoring and computing. - : Springer Science and Business Media LLC. - 1387-1307 .- 1573-2614. ; 34:2, s. 197-205
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Forskningsöversikt (refereegranskat)abstract
- This paper reviews 28 papers or commentaries published in Journal of Clinical Monitoring and Computing in 2018 and 2019, within the field of respiration. Papers were published covering endotracheal tube cuff pressure monitoring, ventilation and respiratory rate monitoring, lung mechanics monitoring, gas exchange monitoring, CO2 monitoring, lung imaging, and technologies and strategies for ventilation management.
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| 6. |
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| 7. |
- Pellegrini, Mariangela, et al.
(författare)
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Expiratory Diaphragm Activity Reduces Atelectasis Formation
- 2016
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Konferensbidrag (refereegranskat)abstract
- Rationale. If the diaphragm, known as the major inspiratory muscle, is active also during expiration, it will limit closure of the smallairways as well as cyclic opening and closing of airways and alveoli. We investigated the expiratory role of the diaphragm in conditionsthat promote lung collapse. Methods. Acute lung injury was induced in 8 anesthetized, tracheostomized pigs by repeated lung lavages, targeting a PaO2/FiO2 of 250mmHg. After stabilization, the animals were switched to spontaneous breathing (SB) and underwent a decremental continuous positiveend-expiratory pressure (PEEP) trial of 15, 12, 9, 6, 3 and 0 cmH2O. During steady state conditions, para-diaphragmatic dynamic-CT scans(dCTs) were obtained together with measurements of respiratory variables. In 4 pigs, the same protocol was repeated during mechanicalpressure control ventilation (PCV) in fully muscle-paralyzed animals. The electrical diaphragmatic activity was continuously recordedduring the expiration (EAdiexp) and during apnea (EAdimin). The EAdiexp recording from end-inspiration to end-expiration was dividedinto 4 quartiles (Q1, Q2, Q3, Q4) and the mean value for each of them was expressed as percentage of the EAdi peak. During SB and PCV,the dCT scans collected at end-expiration and half-expiration were identified and the amount of collapse (atelectasis) in that cut wascalculated. The atelectatic tissue was defined as the sum of voxels with a density between -100 and +100 Hounsfield Units. Results. When, during spontaneous breathing, PEEP was lowered from 15 to 6 cmH2O, the EAdiexp increased significantly in all 4quartiles of the expiratory curve (see Figure, left panel). The EAdimin increased when PEEP was reduced from 12 to 0 cmH2O. However,atelectasis did not increase in size until PEEP was below 9 cmH2O. Larger atelectasis was seen during PCV (with no measurable EAdi) thanduring SB at PEEP levels from 9 to 0 cmH2O. This was seen not only at end-expiration, but already half way down the expiration (seeFigure, right panels). Conclusions. The increasing diaphragm activity with decreasing airway pressure during the expiration will protect against atelectasisformation. The effects of the diaphragmatic activity are visible already half way down the expiration. These findings have potentialimplications how to design ventilatory support strategies in a wide range of pathological lung conditions, from chronic obstructivepulmonary disease to acute lung injury.
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| 8. |
- Rylander, Christian, 1960, et al.
(författare)
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Oleic acid lung injury: a morphometric analysis using computed tomography.
- 2004
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Ingår i: Acta anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 48:9, s. 1123-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The oleic acid-induced lung injury (OAI) model is considered to represent the early phase of acute respiratory distress syndrome (ARDS). Its inherent properties are important for the design and the interpretation of interventional studies. The aim of this study was to describe the evolution of morphometric lung changes during OAI using computed tomography (CT) analysis. Furthermore, the effect of a temporary change in positive end-expiratory pressure (PEEP) was evaluated. METHODS: Fifteen anaesthetized pigs were ventilated in volume-controlled mode with a baseline PEEP of 5 cm H(2)O. Helical CT scans were taken at baseline and 1 h after oleic acid injection. The PEEP was then either increased to 10 cm H(2)O (n = 5), decreased to 0 cm H(2)O (n = 5) or kept constant (n = 5) for 30 min. For the next 30 min, the baseline PEEP level was applied in all animals before the final CT scans 2 h after the induction of OAI. Dimensional and volumetric changes were determined from radiographical attenuation values. RESULTS: There was a major decrease in gas volume and an increase in tissue volume within the first hour. A net increase in total lung volume, with a larger transverse area but no displacement of the diaphragm, was manifest after 2 h. A minor increase in volume of non-aerated lung, located to the caudal region, was observed during the second hour. The tidal volume was redistributed to the middle and apical regions. The temporary change in PEEP did not influence the morphological progress of OAI. CONCLUSION: Decreased gas volume and increased tissue volume are the dominating morphometric characteristics of oleic acid lung injury, occurring mainly within the first hour. With these changes manifest, the course of injury is not affected by a limited period of moderately changed PEEP during the second hour. The net increase of total lung volume suggests a predominance of oedema formation over airway and alveolar collapse.
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