| 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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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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| 3. |
- Tapani, Andreas, et al.
(författare)
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Results from the analysis and input to the development and validation of the statistical models
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of Deliverable 5.1 of the ITERATE project is to present results of analyses made of the data collected in the ITERATE WP4 driving simulator experiments. The ITERATE WP4 driving simulator experiments consisted of train and car driving experiments carried out on a portable car/train driving simulator platform and in full scale car and train driving simulators. The analyses conducted and presented in this deliverable consist of hypothesis testing, cluster analysis and development of a procedure for estimation of parameters of relationships in the WP6 UMD simulation model. Findings from the analyses show that country was found to be an important factor in both the car and train driving experiment. Significant effects of the factor workload were also established in many of the events analysed. The conclusion of comparisons between the data collected in the portable and full scale simulators is that the ITERATE portable driving simulator platform is a suitable tool to studying underlying factors controlling driver behaviour at least for the car diving. However, there were differences between the portable and full scale train simulators. These differences have to be considered in later stages of the project. The next step within the ITERATE project is to estimate relevant relationships in the WP6 UMD simulation model based on the findings of the analyses presented in this deliverable. The analyses presented will also be important as inspiration for other studies outside of the present project with the ITERATE driving simulator dataset as an important source of data.
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| 4. |
- Wallenius, Joel, et al.
(författare)
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Exonic trinucleotide repeat expansions in ZFHX3 cause spinocerebellar ataxia type 4 : A poly-glycine disease.
- 2024
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Ingår i: American Journal of Human Genetics. - 0002-9297 .- 1537-6605. ; 111:1, s. 82-95
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Tidskriftsartikel (refereegranskat)abstract
- Autosomal-dominant ataxia with sensory and autonomic neuropathy is a highly specific combined phenotype that we described in two Swedish kindreds in 2014; its genetic cause had remained unknown. Here, we report the discovery of exonic GGC trinucleotide repeat expansions, encoding poly-glycine, in zinc finger homeobox 3 (ZFHX3) in these families. The expansions were identified in whole-genome datasets within genomic segments that all affected family members shared. Non-expanded alleles carried one or more interruptions within the repeat. We also found ZFHX3 repeat expansions in three additional families, all from the region of Skåne in southern Sweden. Individuals with expanded repeats developed balance and gait disturbances at 15 to 60 years of age and had sensory neuropathy and slow saccades. Anticipation was observed in all families and correlated with different repeat lengths determined through long-read sequencing in two family members. The most severely affected individuals had marked autonomic dysfunction, with severe orthostatism as the most disabling clinical feature. Neuropathology revealed p62-positive intracytoplasmic and intranuclear inclusions in neurons of the central and enteric nervous system, as well as alpha-synuclein positivity. ZFHX3 is located within the 16q22 locus, to which spinocerebellar ataxia type 4 (SCA4) repeatedly had been mapped; the clinical phenotype in our families corresponded well with the unique phenotype described in SCA4, and the original SCA4 kindred originated from Sweden. ZFHX3 has known functions in neuronal development and differentiation n both the central and peripheral nervous system. Our findings demonstrate that SCA4 is caused by repeat expansions in ZFHX3.
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| 5. |
- Almobarak, Bilal, et al.
(författare)
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Exposure to nonanoic acid alters small intestinal neuroendocrine tumor phenotype
- 2023
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundSmall intestinal neuroendocrine tumors (SI-NET) are highly differentiated and genetically stable malignant tumors, yet they often present with advanced metastatic spread at the time of diagnosis. In contrast to many other types of malignant tumors, primary SI-NET are often asymptomatic and typically smaller in size compared to adjacent lymph node metastases. This study explores the hypothesis that stimulating the chemosensing olfactory receptor 51E1 (OR51E1) decreases SI-NET proliferation suggesting a mechanism that explains a difference in proliferative rate based on tumor location.MethodsClinical data was used to address difference in tumor size depending on location. A SI-NET tissue microarray was used to evaluate expression of OR51E1 and olfactory marker protein (OMP). Primary cultured tumor cells from 5 patients were utilized to determine the effect of OR51E1 agonist nonanoic acid on metabolic activity. The SI-NET cell line GOT1 was used to determine effects of nonanoic acid on the transcriptome as well as long-term effects of nonanoic acid exposure with regards to cell proliferation, serotonin secretion, alterations of the cell-cycle and morphology.ResultsTumor size differed significantly based on location. OR51E1 and OMP were generally expressed in SI-NET. Primary SI-NET cells responded to nonanoic acid with a dose dependent altered metabolic activity and this was replicated in the GOT1 cell line but not in the MCF10A control cell line. Nonanoic acid treatment in GOT1 cells upregulated transcripts related to neuroendocrine differentiation and hormone secretion. Long-term nonanoic acid treatment of GOT1 cells decreased proliferation, induced senescence, and altered cell morphology.ConclusionOur results raise the possibility that exposure of intraluminal metabolites could represent a mechanism determining aspects of the SI-NET tumor phenotype. However, we could not causally link the observed effects of nonanoic acid exposure to the OR51E1 receptor.
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| 6. |
- Andersson, Andreas, 1980-, et al.
(författare)
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Train-Track-Bridge Interaction for non-ballasted Railway Bridges on High-Speed Lines
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report contains a comprehensive parametric study on the coupled dynamic train–track–bridge interaction (TTBI) system for non-ballasted railway bridges. The existing design limits in Eurocode EN 1990 A2 regarding vertical deck acceleration and vertical deck displacement is compared with the wheel–rail forces and car body acceleration from simulations.The simulations are based on a 2D TTBI model with linear Hertzian contact that allows for loss of contact. The model has been verified against both other numerical simulations as well as experiments, all with good agreement. The parametric study consists of a large number of theoretical bridges, all optimized to reach the limit of either vertical deck acceleration or vertical deck displacement. The study comprises both single- and double track bridges.The track irregularities are found to be of paramount importance. Two different levels are therefore studied; “higher track quality” corresponding to a well-maintained track for high-speed railways and “lower track quality” corresponding to the Alert Limit in EN 13848-5. The final conclusions are based on the “lower track quality” in order not to underestimate the risk of running safety and passenger comfort. Simulations with the bridge excluded show that the additional contribution from the bridge is low, especially for the lower track quality.The existing limit for vertical deck acceleration is set to 5 m/s2 in EN 1990 A2 and is based on a very simple assumption of the gravity acceleration reduced by a factor 2. The results in this report show that this likely is a too conservative measure of the running safety. Based on the wheel–rail forces from the simulations, the resulting wheel unloading factor and duration of contact loss does not reach critical values before the deck acceleration is beyond 30 m/s2.In EN 1990 A2, a vertical car body acceleration of 1 m/s2 is stipulated as “very good level of comfort” and is indirectly limited by the vertical deck displacement. Good agreement is generally found in the simulations between deck displacement and expected car body acceleration. In the simulations, the limit for car body acceleration is always exceeded before the running safety is compromised.
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| 7. |
- Andersson, Andreas, et al.
(författare)
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Train-Track-Bridge Interaction for non-ballasted Railway Bridges on High-Speed Lines
- 2018
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Ingår i: Railways 2018.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents the result from a parametric study of the dynamic response of railway bridges during train passage. A 2D coupled train-track-bridge interaction (TTBI) model is used to calculate the response from both the bridge and the vehicle.To assure traffic safety and riding comfort, Eurocode EN 1990/A2 gives a set of design limits for railway bridges on high-speed lines. The vertical bridge deck acceleration and displacement are often of main interest. For bridges with non-ballasted tracks the vertical deck acceleration is limited to 5 m/s2, simply obtained as the gravity divided by a safety factor 2, under the assumption that loss of wheel-rail contact will occur at 1g. The vertical bridge deck displacement is an implicit measure to assure riding comfort, based on a limited set of simulations carried out in the 1980ies and 1990ies.The main aim of this paper is to study the relation between the vertical bridge deck acceleration and the risk of derailment as well as the relation between the vertical deck displacement to the riding comfort. The risk of derailment is estimated both as a wheel-unloading factor based on the filtered wheel-rail contact forces or as the duration of contact loss based on the unfiltered wheel-rail contact forces.A large set of theoretical bridges are studied, all optimised to reach the design limits according to EN 1990/A2 for either vertical bridge deck acceleration or displacement. The results show that there is no risk of derailment until the deck acceleration exceeds 30 m/s2. Based on the present parametric study, it appears that the current limit for vertical deck acceleration of non-ballasted railway bridges is very conservative but that the limits for vertical deck displacement is in the correct order of magnitude. It is further concluded that the magnitude of rail irregularities is of great importance, often causing larger dynamic response in the vehicle than due to the vibration of the bridge.
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| 8. |
- Andersson, Andreas, Ph.D. 1980-, et al.
(författare)
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Train-track-bridge interaction to allow for increased axle loads on iron ore lines
- 2021
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Ingår i: Proceedings of the Second International Conference on Rail Transportation. - : American Society of Civil Engineers (ASCE).
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Konferensbidrag (refereegranskat)abstract
- This paper presents dynamic analyses of railway bridges traversed by heavy freight trains, with application to the iron ore line in the North of Sweden. The main objective is to show that the allowable axle load can be increased as a result of lower dynamic effects compared to current design codes, especially for short- and medium span bridges. Simulations are based on a 2D traintrack-bridge interaction model and a large set of sampled realistic track irregularities. Using a semi-probabilistic approach, the results show that for short span bridges the dynamic effects is less than 15% compared to more than 40% in current codes. For span lengths longer than 10 m the dynamic effects are less than 5% according to the simulations. A parametric study shows that the dynamic effects are proportional to the standard deviation of the track irregularities and that the main governing effects of the train is the un-sprung mass.
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| 9. |
- Arvidsson, Andreas
(författare)
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Development of an Automatic Reduction Tool for Chemical Mechanisms and an Optimized Sparse Matrix Solver for Systems of Differential and Algebraic Equations
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Abstract An N-Heptane mechanism and a Methane/Propane mechanism have been reduced by an Automatic Reduction Tool (ART) and simulated with two different solver combinations, which solve the set of ordinary differential equations governing the time evolution of the species simultaneously with solving algebraic equations for species that can be considered to be in quasi steady state. The most successful of the two solver combinations is an optimized combination of Newton solvers. The algebraic part of the solver is based on a Newton solver and is given a speed-up by using the fact that the sparseness pattern of the Jacobian is constant in time. This allows for automatically written source code and an optimization of the sparseness pattern in a preprocessing step. The optimization method is based on a simulated annealing procedure that minimizes the number of operations in the algebraic part of the solver. The speed-up of the Newton solver for the algebraic equations is one of the major developments presented in this thesis. The other one is the development of the ART and the reduction of the N-Heptane and the Methane/Propane mechanisms using the ART. A reduction down to 37 out of 110 species and 23 out of 118 species is achieved for the N-Heptane and Methane/Propane mechanism respectively, while the accuracy of the solution is maintained and the CPU time is significantly lower than that of the detailed mechanism. Less, but still greatly reduced mechanisms are generated for larger ranges of physical conditions. Also, the two solver combinations were implemented into a commercial Computational Fluid Dynamics (CFD) code. CFD simulations were then performed for a detailed and reduced mechanism. The implementation involving the optimized combination of Newton solvers resulted in a speed-up for the reduced mechanism compared to the detailed mechanism, while the accuracy of important species for the reduced mechanism was well within acceptable limits.
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| 10. |
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