| 1. |
- Ehn, Andreas, et al.
(författare)
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Fluorescence lifetime imaging in a flame
- 2011
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 33, s. 807-813
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Tidskriftsartikel (refereegranskat)abstract
- A novel method for two-dimensional fluorescence lifetime imaging is presented. The technique is demonstrated on averaged planar laser-induced fluorescence (PLIF) signals recorded in a flame. Although demonstrated on averaged images, the concept applies equally well to single-shot images. Formaldehyde was probed through pico-second excitation at 355 nm in a rich methane/oxygen flame (Phi = 2.6). Images were recorded with a dual ICCD camera detection setup with different gate characteristics of the two cameras. The recorded images were analyzed using simulated values of LIF signal detection to generate two-dimensional images of effective lifetimes. Measured lifetimes range from roughly 1 to 4.5 ns. The lifetime image data were used for quenching correction of the LIF images, which, after correction, showed better qualitative agreement compared to a formaldehyde concentration profile simulated with the GRI 3.0 mechanism. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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| 2. |
- Ehn, Andreas, et al.
(författare)
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Quantitative oxygen concentration imaging in toluene atmospheres using Dual Imaging with Modeling Evaluation
- 2013
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Ingår i: Experiments in Fluids. - : Springer Science and Business Media LLC. - 1432-1114 .- 0723-4864. ; 54:1, s. 1433-1433
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence lifetimes of toluene as a function of oxygen concentration in toluene/nitrogen/oxygen mixtures have been measured at room temperature using picosecond-laser excitation of the S-1-S-0 transition at 266 nm. The data satisfy the Stern-Volmer relation with high accuracy, providing an updated value of the Stern-Volmer slope. A newly developed fluorescence lifetime imaging scheme, called Dual Imaging with Modeling Evaluation (DIME), is evaluated and successfully demonstrated for quantitative oxygen concentration imaging in toluene-seeded O-2/N-2 gas mixtures.
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| 3. |
- Ehn, Andreas, et al.
(författare)
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Single-laser shot fluorescence lifetime imaging on the nanosecond timescale using a Dual Image and Modeling Evaluation algorithm
- 2012
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Ingår i: Optics Express. - 1094-4087. ; 20:3, s. 3043-3056
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Tidskriftsartikel (refereegranskat)abstract
- A novel technique, designated dual imaging and modeling evaluation (DIME), for evaluating single-laser shot fluorescence lifetimes is presented. The technique is experimentally verified in a generic gas mixing experiment to provide a clear demonstration of the rapidness and sensitivity of the detector scheme. Single-laser shot fluorescence lifetimes of roughly 800 ps with a standard deviation of similar to 120 ps were determined. These results were compared to streak camera measurements. Furthermore, a general fluorescence lifetime determination algorithm is proposed. The evaluation algorithm has an analytic, linear relationship between the fluorescence lifetime and detector signal ratio. In combination with the DIME detector scheme, it is a faster, more accurate and more sensitive approach for rapid fluorescence lifetime imaging than previously proposed techniques. Monte Carlo simulations were conducted to analyze the sensitivity of the detector scheme as well as to compare the proposed evaluation algorithm to previously presented rapid lifetime determination algorithms. (C) 2012 Optical Society of America
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| 4. |
- Ehn, Maria, et al.
(författare)
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Users perspectives on interactive distance technology enabling home-based motor training for stroke patients
- 2015
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Ingår i: Stud. Health Technol. Informatics. - : IOS Press. - 9781614995159 ; , s. 145-152
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Konferensbidrag (refereegranskat)abstract
- The aim of this work has been to develop a technical support enabling home-based motor training after stroke. The basis for the work plan has been to develop an interactive technical solution supporting three different groups of stroke patients: (1) patients with stroke discharged from hospital with support from neuro team; (2) patients with stroke whose support from neuro team will be phased out and (3) patients living with impaired motor functions long-term. The technology has been developed in close collaboration with end-users using a method earlier evaluated and described [12]. This paper describes the main functions of the developed technology. Further, results from early user-tests with end-users, performed to identify needs for improvements to be carried out during further technical development. The developed technology will be tested further in a pilot study of the safety and, usefulness of the technology when applied as a support for motor training in three different phases of the post-stroke rehabilitation process.
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| 5. |
- Jakobsson, Hugo, et al.
(författare)
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Adrenal venous sampling: The learning curve of a single interventionalist with 282 consecutive procedures
- 2018
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Ingår i: Diagnostic and Interventional Radiology. - : Galenos Yayinevi. - 1305-3825 .- 1305-3612. ; 24:2, s. 89-93
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE Primary aldosteronism (PA) is a common cause of secondary hypertension. Adrenal venous sampling (AVS) is the gold standard for assessing laterality of PA, which is of paramount importance to decide adequate treatment. AVS is a technically complicated procedure with success rates ranging between 30% and 96%. The aim of this study was to investigate the success rate of AVS over time, performed by a single interventionalist. METHODS This was a retrospective study based on consecutive AVS procedures performed by a single operator between September 2005 and June 2016. Data on serum concentrations of aldosterone and cortisol from right and left adrenal vein, inferior vena cava, and peripheral vein were collected and selectivity index (SI) calculated. Successful AVS was defined as SI >5. RESULTS In total, 282 AVS procedures were performed on 269 patients, 168 men (62%) and 101 women (38%), with a mean age of 55±11 years (range, 26–78 years). Out of 282 AVS procedures, 259 were successful, giving an overall success rate of 92%. The most common reason for failure was inability to localize the right adrenal vein (n=16; 76%). The success rates were 63%, 82%, and 94% during the first, second, and third years, respectively. During the last 8 years the success rate was 95%, and on average 27 procedures were performed annually. CONCLUSION Satisfactory AVS success rate was achieved after approximately 36 procedures and satisfactory success rate was maintained by performing approximately 27 procedures annually. AVS should be limited to few operators that perform sufficiently large number of procedures to achieve, and maintain, satisfactory AVS success rate. © Turkish Society of Radiology 2018.
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| 6. |
- Johansson, Olof, et al.
(författare)
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Photofragmentation laser-induced fluorescence imaging in premixed flames
- 2011
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Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 158:10, s. 1908-1919
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional measurements of primarily hydroperoxyl radicals (HO2) are, for the first time, demonstrated in flames. The measurements are performed in different Bunsen-type premixed flames (H-2/O-2. CH4/O-2, and CH4/air) using photofragmentation laser-induced fluorescence (PF-LIF). Photofragmentation is done by laser radiation at 266 nm, and the generated OH photofragments are probed through fluorescence induced by a laser tuned to the Q(1)(5) transition at 282.75 nm. The signal due to naturally occurring OH radicals, recorded by having the photolysis laser blocked, is subtracted, providing an image that reflects the concentration of OH fragments generated by photolysis, and hence the presence of primarily HO2, but also smaller contributions from H2O2 and, for the methane flames, CH3O2. For the methane flames the measured radial profiles of OH photofragments and natural OH agree well with corresponding profiles calculated for laminar, one-dimensional, premixed flames using CHEMKIN-II with the Konnov detailed C/H/N/O reaction mechanism. An interfering signal contribution is observed in the product zone of the methane flames. It is concluded that the major source for the interference is most likely hot CO2, from which 0 atoms are produced by photolysis, and OH is rapidly formed as the O atoms react with H2O and H-2. This conclusion is supported by the fact that the interference is absent for the hydrogen flame, but appears when CO2 is seeded into the flame. Another strong indication is that the Konnov mechanism predicts a similar buildup of OH after photolysis. (C) 2011 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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| 7. |
- Papakokkinou, Eleni, et al.
(författare)
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Adrenal venous sampling in patients with ACTH-independent hypercortisolism
- 2019
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Ingår i: Endocrine. - : Springer Science and Business Media LLC. - 1355-008X .- 1559-0100. ; 66:2
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Tidskriftsartikel (refereegranskat)abstract
- © 2019, The Author(s). Purpose: To study the usefulness of adrenal venous sampling (AVS) in distinguishing unilateral from bilateral cortisol production in patients with ACTH-independent hypercortisolism and bilateral adrenal lesions, or morphologically normal adrenal glands. Methods: A retrospective analysis of ten consecutive patients with ACTH-independent hypercortisolism who underwent AVS at our institution between 2009 and 2017. Unilateral dominant cortisol production was defined as a side-to-side cortisol/aldosterone lateralization ratio >2. Results: Four of ten patients had overt Cushing’s syndrome. Of these, two had bilateral adrenal lesions on computed tomography and two had normal adrenal glands. One of the two patients with bilateral adrenal lesions had, based on the AVS, a unilateral dominant cortisol production. Following unilateral adrenalectomy the patient developed adrenal insufficiency. The other three patients were considered to have bilateral cortisol production and underwent bilateral adrenalectomy. Six patients had a mild autonomous cortisol secretion and bilateral adrenal lesions. Based on AVS, one patient was considered to have unilateral dominant cortisol production, underwent unilateral adrenalectomy and developed transient adrenal insufficiency postoperatively. Conclusions: AVS may contribute to appropriate treatment in patients with ACTH-independent hypercortisolism and bilateral adrenal lesions. In our series, AVS was helpful in the decision-making of two out of ten patients, avoiding chronic treatment with steroidogenesis inhibitors, or inappropriate bilateral adrenalectomy.
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| 8. |
- Trimpou, Penelope, 1973, et al.
(författare)
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Diagnostic value of the water deprivation test in the polyuria-polydipsia syndrome.
- 2017
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Ingår i: Hormones. - : Springer Science and Business Media LLC. - 2520-8721 .- 1109-3099. ; 16:4, s. 414-422
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Tidskriftsartikel (refereegranskat)abstract
- Diabetes insipidus (DI) and primary polydipsia (PP) are characterised by polyuria and polydipsia. It is crucial to differentiate between these two disorders since the treatment is different. The aim of this study was to evaluate the diagnostic value of the short and an extended variant of the water deprivation test (WDT) and of measuring urinary vasopressin (AVP) in patients with polyuria and polydipsia.A retrospective, single-centre study based on WDTs performed between 2004 and 2014 including 104 consecutive patients with the polyuria-polydipsia syndrome. During a strict water deprivation, weight, urinary osmolality, urinary vasopressin and specific gravity were collected until one of the following was reached: i) >3% weight reduction, ii) Urinary specific gravity >1.020 or, urinary osmolality >800 mOsm/L, iii) Intolerable adverse symptoms such as excessive thirst.Out of 104 patients (67 women, 37 men), 21 (20%) were diagnosed with DI and 83 (80%) with PP. The median (interquartile range; range) test duration was 14 hours (10-16; 3-36) in patients with DI and 18 hours (14-24; 7-48) in patients with PP (P=0.011). Of those diagnosed with PP, 22 (26%) did not reach urinary specific gravity >1.020 nor urine osmolality >800 mOsm/L. Urine AVP did not overlap between patients with PP and patients with central DI.The short WDT is of limited value in the diagnostic work-up of polydipsia and polyuria and a partial DI may have been missed in every fourth patient diagnosed with PP. Urinary AVP has excellent potential in discriminating PP from central DI.
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| 9. |
- Trimpou, Penelope, 1973, et al.
(författare)
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The diagnostic performance of copeptin in clinical practice: A prospective study
- 2024
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Ingår i: CLINICAL ENDOCRINOLOGY. - 0300-0664 .- 1365-2265.
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivePlasma copeptin is a relatively new biomarker for evaluation of arginine vasopressin (AVP) secretion. The aim of this study was to test the diagnostic performance of copeptin in patients with polyuria-polydipsia syndrome. Design, Patients and MeasurementsThis was a prospective study where 88 patients with polyuria-polydipsia syndrome were evaluated with a water deprivation test (WDT). Weight, urine osmolality, urine specific gravity, and plasma copeptin were collected at baseline, after 8 h, and at termination of the WDT when one of the following had been reached: (i) >3% weight reduction, (ii) urine specific gravity >1.017 or urine osmolality >600 mOsm/kg, or (iii) intolerable adverse symptoms. ResultsOf 88 patients (57 women), 21 (24%) were diagnosed with central diabetes insipidus (cDI), 5 (6%) with nephrogenic DI (nDI), and 62 (71%) with primary polydipsia (PP). Median (interquartile range) copeptin at baseline was 1.7 (1.4-2.5) pmol/L in cDI, 22 (18-65) pmol/L in nDI, and 2.7 (2-4) pmol/L in PP. After 8 h of WDT, the highest copeptin in patients with cDI was 4.0 pmol/L. In patients with PP: (i) 41 had urine osmolality <600 mOsm/kg, 7 (17%) of these had copeptin >4.0 pmol/L, (ii) 21 had urine osmolality >= 600 mOsm/kg, 14 (67%) of these had copeptin >4.0 pmol/L. ConclusionsCopeptin >4.0 pmol/L after an overnight WDT can be used to rule out cDI and copeptin >= 21 pmol/L at baseline to diagnose nDI. The diagnostic performance of copeptin in the context of the WDT is otherwise limited in the diagnostic work-up of patients with polyuria-polydipsia syndrome.
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