| 1. |
- Goebel, Claudia, 1988, et al.
(författare)
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Long term (4 years) performance of Co/Ce coated 441 for SOFC interconnect applications
- 2017
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; 78:1, s. 1675-1679
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Konferensbidrag (refereegranskat)abstract
- Co/Ce coated 441 samples were exposed at 800°C in laboratory air for up to 37 000 h and subsequently characterized using different techniques. Mass gain data of all samples were recorded throughout exposure. Cr-evaporation measurements were conducted and compared with unexposed Co/Ce coated AISI 441 as well as unexposed and uncoated AISI 441. Furthermore SEM analysis on BIB cross-sections was performed on 7 000 h, 23 000 h and 35 000 h exposed Co/Ce coated 441.
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| 2. |
- Sudireddy, B. R., et al.
(författare)
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Development of Robust Metal-Supported SOFCs and Stack Components in EU METSAPP Consortium
- 2017
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Ingår i: Fuel Cells. - : Wiley. - 1615-6846 .- 1615-6854. ; 17:4, s. 508-516
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Tidskriftsartikel (refereegranskat)abstract
- The potential of MS-SOFCs was demonstrated through the previous EU METSOFC project, which concluded that the development of oxidation resistant novel metal-supported solid oxide fule cell (MS-SOFC) design and stack is the requirement to advance this technology to the next level. The following EU METSAPP project has been executed with an overall aim of developing advanced metal-supported cells and stacks based on a robust, reliable and up-scalable technology. During the project, oxidation resistant nanostructured anodes based on modified SrTiO3 were developed and integrated into MS-SOFCs to enhance their robustness. In addition, the manufacturing of metal-supported cells with different geometries, scalability of the manufacturing process was demonstrated and more than 200 cells with an area of approximate to 150 cm(2) were produced. The electrochemical performance of different cell generations was evaluated and best performance and stability combination was observed with doped SrTiO3 based anode designs. Furthermore, numerical models to understand the corrosion behavior of the MS-SOFCs were developed and validated. Finally, the cost effective concept of coated metal interconnects was developed, which resulted in 90% reduction in Cr evaporation, three times lower Cr2O3 scale thickness and increased lifetime. The possibility of assembling these cells into two radically different stack designs was demonstrated.
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| 3. |
- Tengvall, Katarina, 1980-, et al.
(författare)
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Molecular mimicry between Anoctamin 2 and Epstein-Barr virus nuclear antigen 1 associates with multiple sclerosis risk
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 116:34, s. 16955-16960
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Tidskriftsartikel (refereegranskat)abstract
- Multiple sclerosis (MS) is a chronic inflammatory, likely autoimmune disease of the central nervous system with a combination of genetic and environmental risk factors, among which Epstein-Barr virus (EBV) infection is a strong suspect. We have previously identified increased autoantibody levels toward the chloride-channel protein Anoctamin 2 (ANO2) in MS. Here, IgG antibody reactivity toward ANO2 and EBV nuclear antigen 1 (EBNA1) was measured using bead-based multiplex serology in plasma samples from 8,746 MS cases and 7,228 controls. We detected increased anti-ANO2 antibody levels in MS (P = 3.5 x 10(-36)) with 14.6% of cases and 7.8% of controls being ANO2 seropositive (odds ratio [OR] = 1.6; 95% confidence intervals [95% CI]: 1.5 to 1.8). The MS risk increase in ANO2-seropositive individuals was dramatic when also exposed to 3 known risk factors for MS: HLA-DRB1*15: 01 carriage, absence of HLA-A*02: 01, and high anti-EBNA1 antibody levels (OR = 24.9; 95% CI: 17.9 to 34.8). Reciprocal blocking experiments with ANO2 and EBNA1 peptides demonstrated antibody cross-reactivity, mapping to ANO2 [aa 140 to 149] and EBNA1 [aa 431 to 440]. HLA gene region was associated with anti-ANO2 antibody levels and HLADRB1*04: 01 haplotype was negatively associated with ANO2 seropositivity (OR = 0.6; 95% CI: 0.5 to 0.7). Anti-ANO2 antibody levels were not increased in patients from 3 other inflammatory disease cohorts. The HLA influence and the fact that specific IgG production usually needs T cell help provides indirect evidence for a T cell ANO2 autoreactivity in MS. We propose a hypothesis where immune reactivity toward EBNA1 through molecular mimicry with ANO2 contributes to the etiopathogenesis of MS.
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| 4. |
- Warntjes, Marcel Jan Bertus, et al.
(författare)
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Improved Precision of Automatic Brain Volume Measurements in Patients with Clinically Isolated Syndrome and Multiple Sclerosis Using Edema Correction
- 2018
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Ingår i: American Journal of Neuroradiology. - : AMER SOC NEURORADIOLOGY. - 0195-6108 .- 1936-959X. ; 39:2, s. 296-302
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: The presence of edema will result in increased brain volume, which may obscure progressing brain atrophy. Similarly, treatment-induced edema reduction may appear as accelerated brain tissue loss (pseudoatrophy). The purpose of this study was to correlate brain tissue properties to brain volume, to investigate the possibilities for edema correction and the resulting improvement of the precision of automated brain volume measurements. MATERIALS AND METHODS: A group of 38 patients with clinically isolated syndrome or newly diagnosed MS were imaged at inclusion and after 1, 2, and 4 years using an MR quantification sequence. Brain volume, relaxation rates (R-1 and R-2), and proton density were measured by automated software. RESULTS: The reduction of normalized brain volume with time after inclusion was 0.273%/year. The mean SDs were 0.508%, 0.526%, 0.454%, and 0.687% at baseline and 1, 2, and 4 years. Linear regression of the relative change of normalized brain volume and the relative change of R-1, R-2, and proton density showed slopes of -0.198 (P amp;lt; .001), 0.156 (P = .04), and 0.488 (P amp;lt; .001), respectively. After we applied the measured proton density as a correction factor, the mean SDs decreased to 24.2%, 4.8%, 33.3%, and 17.4%, respectively. The observed atrophy rate reduced from 0.273%/year to 0.238%/year. CONCLUSIONS: Correlations between volume and R-1, R-2, and proton density were observed in the brain, suggesting that a change of brain tissue properties can affect brain volume. Correction using these parameters decreased the variation of brain volume measurements and may have reduced the effect of pseudoatrophy.
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| 5. |
- Al-Chalabi, Hussan, et al.
(författare)
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Case Study: Model for Economic Lifetime of Drilling Machines in the Swedish Mining Industry
- 2015
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Ingår i: The Engineering Economist. - 0013-791X .- 1547-2701. ; 60:2, s. 138-154
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to develop a practical economic replacement decision model to identify the economic lifetime of a mining drilling machine. A data driven optimisation model was developed for operating and maintenance costs, purchase price and machine resale value. Equivalent present value of these costs by using discount rate was considered. The proposed model shows that the absolute optimal replacement time (ORT) of a drilling machine used in one underground mine in Sweden is 115 months. Sensitivity and regression analysis show that the maintenance cost has the largest impact on the ORT of this machine. The proposed decision making model is applicable and useful and can be implemented within the mining industry.
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| 6. |
- Al-Chalabi, Hussan, Associate Senior Lecturer, 1972-, et al.
(författare)
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Time Series Forecasting using ARIMA Model : A Case Study of Mining Face Drilling Rig
- 2018
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Ingår i: ADVCOMP 2018. - : International Academy, Research and Industry Association (IARIA). ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- This study implements an Autoregressive Integrated Moving Average (ARIMA) model to forecast total cost of a face drilling rig used in the Swedish mining industry. The ARIMA model shows different forecasting abilities using different values of ARIMA parameters (p, d, q). However, better estimation for the ARIMA parameters is required for accurate forecasting. Artificial intelligence, such as multi objective genetic algorithm based on the ARIMA model, could provide other possibilities for estimating the parameters. Time series forecasting is widely used for production control, production planning, optimizing industrial processes and economic planning. Therefore, the forecasted total cost data of the face drilling rig can be used for life cycle cost analysis to estimate the optimal replacement time of this rig.
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| 7. |
- Al-Douri, Yamur K., et al.
(författare)
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Time Series Forecasting using a Two-level Multi-objective Genetic Algorithm : A case study of cost data for tunnel fans
- 2018
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Ingår i: Algorithms. - : MDPI. - 1999-4893. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to develop a novel two-level multi-objective genetic algorithm (GA) to optimize time series forecasting data for fans used in road tunnels by the Swedish Transport Administration (Trafikverket). The first level is for the process of forecasting time series cost data, while the second level evaluates the forecasting. The first level implements either a multi-objective GA based on the ARIMA model or based on the dynamic regression model. The second level utilises a multi-objective GA based on different forecasting error rates to identify a proper forecasting. Our method is compared with the ARIMA model only. The results show the drawbacks of time series forecasting using the ARIMA model. In addition, the results of the two-level model show the drawbacks of forecasting using a multi-objective GA based on the dynamic regression model. A multi-objective GA based on the ARIMA model produces better forecasting results. In the second level, five forecasting accuracy functions help in selecting the best forecasting. Selecting a proper methodology for forecasting is based on the averages of the forecasted data, the historical data, the actual data and the polynomial trends. The forecasted data can be used for life cycle cost (LCC) analysis.
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| 8. |
- Al-Douri, Yamur K., et al.
(författare)
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Time Series Forecasting using Genetic Algorithm : A Case Study of Maintenance Cost Data For Tunnel Fans
- 2018
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Ingår i: ADVCOMP 2018. - : International Academy, Research and Industry Association (IARIA). ; , s. 4-9
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Konferensbidrag (refereegranskat)abstract
- Time series forecasting is widely used as a basis for economic planning, production planning, production control and optimizing industrial processes. The aim of this study has been to develop a novel two-level Genetic Algorithm (GA) to optimize time series forecasting in order to forecast cost data for fans used in road tunnels by the Swedish Transport Administration (Trafikverket). The first level of the GA is responsible for the process of forecasting time series cost data, while the second level evaluates the forecasting. The first level implements GA based on the Autoregressive integrated moving average (ARIMA) model. The second level utilizes a GA based on forecasting error rate to identify a proper forecasting. The results show that GA based on the ARIMA model produces better forecasting results for the labor cost data objects. It was found that a multi-objective GA based on the ARIMA model showed an improved performance. The forecasted data can be used for Life cycle cost (LCC) analysis.
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| 9. |
- Al-Douri, Yamur K.
(författare)
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Two-Level Multi-Objective Genetic Algorithm for Risk-Based Life Cycle Cost Analysis
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Artificial intelligence (AI) is one of the fields in science and engineering and encompasses a wide variety of subfields, ranging from general areas (learning and perception) to specific topics, such as mathematical theorems. AI and, specifically, multi-objective genetic algorithms (MOGAs) for risk-based life cycle cost (LCC) analysis should be performed to estimate the optimal replacement time of tunnel fan systems, with a view towards reducing the ownership cost and the risk cost and increasing company profitability from an economic point of view. MOGA can create systems that are capable of solving problems that AI and LCC analyses cannot accomplish alone.The purpose of this thesis is to develop a two-level MOGA method for optimizing the replacement time of reparable system. MOGA should be useful for machinery in general and specifically for reparable system. This objective will be achieved by developing a system that includes a smart combination of techniques by integrating MOGA to yield the optimized replacement time. Another measure to achieve this purpose is implementing MOGA in clustering and imputing missing data to obtain cost data, which could help to provide proper data to forecast cost data for optimization and to identify the optimal replacement time.In the first stage, a two-level MOGA is proposed to optimize clustering to reduce and impute missing cost data. Level one uses a MOGA based on fuzzy c-means to cluster cost data objects based on three main indices. The first is cluster centre outliers; the second is the compactness and separation ( ) of the data points and cluster centres; the third is the intensity of data points belonging to the derived clusters. Level two uses MOGA to impute the missing cost data by using a valid data period from that are reduced data in size. In the second stage, a two-level MOGA is proposed to optimize time series forecasting. Level one implements MOGA based on either an autoregressive integrated moving average (ARIMA) model or a dynamic regression (DR) model. Level two utilizes a MOGA based on different forecasting error rates to identify proper forecasting. These models are applied to simulated data for evaluation since there is no control of the influenced parameters in all of the real cost data. In the final stage, a two-level MOGA is employed to optimize risk-based LCC analysis to find the optimal replacement time for reparable system. Level one uses a MOGA based on a risk model to provide a variation of risk percentages, while level two uses a MOGA based on an LCC model to estimate the optimal reparable system replacement time.The results of the first stage show the best cluster centre optimization for data clustering with low and high intensity. Three cluster centres were selected because these centres have a geometry that is suitable for the highest data reduction of 27%. The best optimized interval is used for imputing missing data. The results of the second stage show the drawbacks of time series forecasting using a MOGA based on the DR model. The MOGA based on the ARIMA model yields better forecasting results. The results of the final stage show the drawbacks of the MOGA based on a risk-based LCC model regarding its estimation. However, the risk-based LCC model offers the possibility of optimizing the replacement schedule.However, MOGA is highly promising for allowing optimization compared with other methods that were investigated in the present thesis.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Alkasalias, Twana, et al.
(författare)
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RhoA knockout fibroblasts lose tumor-inhibitory capacity in vitro and promote tumor growth in vivo
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:8, s. E1413-E1421
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Tidskriftsartikel (refereegranskat)abstract
- Fibroblasts are a main player in the tumor-inhibitory microenvironment. Upon tumor initiation and progression, fibroblasts can lose their tumor-inhibitory capacity and promote tumor growth. The molecular mechanisms that underlie this switch have not been defined completely. Previously, we identified four proteins over-expressed in cancer-associated fibroblasts and linked to Rho GTPase signaling. Here, we show that knocking out the Ras homolog family member A (RhoA) gene in normal fibroblasts decreased their tumor-inhibitory capacity, as judged by neighbor suppression in vitro and accompanied by promotion of tumor growth in vivo. This also induced PC3 cancer cell motility and increased colony size in 2D cultures. RhoA knockout in fibroblasts induced vimentin intermediate filament reorganization, accompanied by reduced contractile force and increased stiffness of cells. There was also loss of wide F-actin stress fibers and large focal adhesions. In addition, we observed a significant loss of a-smooth muscle actin, which indicates a difference between RhoA knockout fibroblasts and classic cancer-associated fibroblasts. In 3D collagen matrix, RhoA knockout reduced fibroblast branching and meshwork formation and resulted in more compactly clustered tumor-cell colonies in coculture with PC3 cells, which might boost tumor stem-like properties. Coculturing RhoA knockout fibroblasts and PC3 cells induced expression of proinflammatory genes in both. Inflammatory mediators may induce tumor cell stemness. Network enrichment analysis of transcriptomic changes, however, revealed that the Rho signaling pathway per se was significantly triggered only after coculturing with tumor cells. Taken together, our findings in vivo and in vitro indicate that Rho signaling governs the inhibitory effects by fibroblasts on tumor-cell growth.
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| 20. |
- Anandika, Rayendra, 1988-, et al.
(författare)
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Non-destructive measurement of artificial near-surface cracks for railhead inspection
- 2019
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Ingår i: Insight. - UK : The British Institute of Non-Destructive Testing. - 1354-2575 .- 1754-4904. ; 61:7, s. 373-379
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Tidskriftsartikel (refereegranskat)abstract
- This paper delivers a study involving the inspection of artificial surface cracks with depths ranging from 0.25-2.5 mm from the surface and with a crack angle of 30°, which is a typical angle for surface cracks in railheads. The inspections were conducted using three different techniques: phased array ultrasonics, single-element ultrasonics and alternating current potential drop (ACPD). For the ultrasonic techniques, the study focused on employing either longitudinal or shear wave signals. In the railway industry, shallow surface cracks in railheads are caused by rolling contact fatigue (RCF). In this study, artificial defects were made, allowing the authors to explore the extent to which the ultrasonic measurement techniques can detect such defects. The negative effect of a dead zone near to the surface in the ultrasonic tests was reduced by using a wedge attachment. A discussion on the extent to which the techniques can be used in field tests was also provided. The most important result is that shallow cracks ranging from 0.25-2.5 mm were successfully characterised with acceptable accuracy. The 2.5 mm-deep crack can be measured with an accuracy of 0.8% using a 20 MHz single-element probe and with an accuracy of 3.5% using a 5 MHz phased array (64 elements, 0.6 mm pitch). The characterisations were performed using a filtering method that was developed in this study.1675605
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| 21. |
- Anandika, Rayendra, 1988-, et al.
(författare)
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Ultrasonic phased array measurement of near-surface cracks in the railhead.
- 2019
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Ingår i: World Congress on Railway Research (WCRR) 2019, Tokyo, Japan. - : Railway Technical Research Institute (RTRI, Japan).
-
Konferensbidrag (refereegranskat)abstract
- Ultrasonic measurement is one of the non-destructive techniques used to inspect defects in the rail body. Ultrasonic measurement is known inappropriate to inspect near-surface defects because of a challenge, called dead-zone. It is signal noise or ringing phenomenon located at near-field in front of the transducer when measuring a material. Due to this, there is difficulty in analysing any measurement signal at this zone, including signals from near-surface defects. In this study, the dead zone was eliminated by attaching wedge to shift the location of noise signals relative to the near-surface defect locations. First, a known-depth defect was measured by using phased array ultrasonic testing (PAUT) to calibrate the ultrasonic equipment and found the best signal gain to eliminate diffuse scattering from defects. Second, a cracked spot on railhead was inspected at the right and left direction of the spot. After the measurement, the inspected spot was sliced into 0.65 mm-thick pieces. From those pieces, the actual crack depth could be observed directly. Based on those sliced pieces, the ultrasonic measurement results were verified. From this study, PAUT delivered accurate measurement result of 3.51-mm crack tip depth with an absolute error of 0.8% - 18%. This accurate result indicates that PAUT can be an alternative to inspect the near-surface crack in railhead.
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| 22. |
- Athron, Peter, et al.
(författare)
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GAMBIT : the global and modular beyond-the-standard-model inference tool
- 2017
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:11
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Tidskriftsartikel (refereegranskat)abstract
- We describe the open-source global fitting package GAMBIT: the Global And Modular Beyond-the-Standard-Model Inference Tool. GAMBIT combines extensive calculations of observables and likelihoods in particle and astroparticle physics with a hierarchical model database, advanced tools for automatically building analyses of essentially any model, a flexible and powerful system for interfacing to external codes, a suite of different statistical methods and parameter scanning algorithms, and a host of other utilities designed to make scans faster, safer and more easily-extendible than in the past. Here we give a detailed description of the framework, its design and motivation, and the current models and other specific components presently implemented in GAMBIT. Accompanying papers deal with individual modules and present flrst GAMBIT results. GAMBIT can be downloaded from gambit.hepforge.org.
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| 23. |
- Athron, Peter, et al.
(författare)
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GAMBIT : the global and modular beyond-the-standard-model inference tool
- 2018
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 78:2
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Tidskriftsartikel (refereegranskat)abstract
- In Ref. (GAMBIT Collaboration: Athron et. al., Eur. Phys. J. C. arXiv: 1705.07908, 2017) we introduced the global-fitting framework GAMBIT. In this addendum, we describe a new minor version increment of this package. GAMBIT 1.1 includes full support for Mathematica backends, which we describe in some detail here. As an example, we backend SUSYHD (Vega and Villadoro, JHEP 07: 159, 2015), which calculates the mass of the Higgs boson in the MSSM from effective field theory. We also describe updated likelihoods in PrecisionBit and DarkBit, and updated decay data included in DecayBit.
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| 24. |
- Attié, David, et al.
(författare)
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A time projection chamber with GEM-based readout
- 2017
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 856, s. 109-118
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Tidskriftsartikel (refereegranskat)abstract
- For the International Large Detector concept at the planned International Linear Collider, the use of time projection chambers (TPC) with micro-pattern gas detector readout as the main tracking detector is investigated. In this paper, results from a prototype TPC, placed in a 1. T solenoidal field and read out with three independent Gas Electron Multiplier (GEM) based readout modules, are reported. The TPC was exposed to a 6. GeV electron beam at the DESY II synchrotron. The efficiency for reconstructing hits, the measurement of the drift velocity, the space point resolution and the control of field inhomogeneities are presented.
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| 25. |
- Bergengren, Jakob, et al.
(författare)
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A recent Dreissena invasion in an old canal system in northern Europe
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Göta Canal was opened in 1832 and connects the Baltic and the Atlantic Sea via the large lakes Vänern and Vättern in south Sweden. Originally used for commercial transport, the canal is today one of the most popular tourist attractions in Sweden with canal cruises, pleasure boating and canoeing. Inventories in 2013 showed that Dreissena mussels recently have invaded lakes, streams and canals in the Motala River drainage basin, i.e. the eastern part of the Göta Canal. According to interviews with local people the mussels may have been there since 2012. During the late summer in 2013 and in 2014 we monitored mussels by scuba diving and we sampled planktonic larval populations in locks and the canal. Dreissena has not dispersed to the western part of the canal system, i.e. west of lake Vättern, where most lakes are oligotrophic with low Ca- andMg-levels. In the eastern part, where several lakes are eutrophic and Ca- and Mg-levels higher, populations have increased very fast. The inventories showed local densities of 10 000 adults m-2 in some eutrophic lakes and larval densities of up to 70 individuals L-1 in the canal water. In Europe, the large range expansion of Dreissena occurred during the late 19th and early 20th century. Why have they dispersed so late into the Göta Canal, i.e. some 170 years after the canal was constructed and some 80 years after they had dispersed to other lakes in Swedennorth of Göta Canal? We can not dismiss dispersal as a a limiting factor but given the historically sustained boat traffic in the region it seems likely that ecological factors may have been important. Freshwaters in Scandinavia are usually low in Ca and Mg and many lakes are characterized by oligotrophic conditions poor in food for filter-feeding Dreissena. In the Göta Canal, changes in biological factors affecting relationships between Dreissena and the regional biota needs to be studied, however. Although we can not explain the delayed invasion we conclude that Dreissena is now established in one of the largest canal system in northern Europe.
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| 26. |
- Bergström, Ida, et al.
(författare)
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Annexin A1 in blood mononuclear cells from patients with coronary artery disease : Its association with inflammatory status and glucocorticoid sensitivity
- 2017
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Annexin A1 (AnxA1) is a key player in resolution of inflammation and a mediator of glucocorticoid actions. In atherosclerotic tissue, increased expression of AnxA1 has been associated with protective plaque-stabilizing effects. Here, we investigated the expression of AnxA1 in peripheral blood mononuclear cells (PBMCs) from patients with coronary artery disease (CAD). Blood was collected from 57 patients with stable CAD (SCAD) and 41 healthy controls. We also included a minor group (n = 10) with acute coronary syndrome (ACS). AnxA1 mRNA was measured in PBMCs. Expression of AnxA1 protein (total and surface-bound) and glucocorticoid receptors (GR) were detected in PBMC subsets by flow cytometry. Also, salivary cortisol, interleukin(IL)-6 and IL-10 in plasma, and LPS-induced cytokine secretion from PBMCs, with or without dexamethasone, were assessed. AnxA1 mRNA was found to be slightly increased in PBMCs from SCAD patients compared with controls. However, protein expression of AnxA1 or GRs in PBMC subsets did not differ between SCAD patients and controls, despite SCAD patients showing a more proinflammatory cytokine profile ex vivo. Only surface expression of AnxA1 on monocytes correlated with dexamethasone-mediated suppression of cytokines. In ACS patients, a marked activation of AnxA1 was seen involving both gene expression and translocation of protein to cell surface probably reflecting a rapid glucocorticoid action modulating the acute inflammatory response in ACS. To conclude, surface expression of AnxA1 on monocytes may reflect the degree of glucocorticoid sensitivity. Speculatively, "normal" surface expression of AnxA1 indicates that anti-inflammatory capacity is impaired in SCAD patients.
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| 27. |
- Blystad, Ida, et al.
(författare)
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Quantitative MRI for Analysis of Active Multiple Sclerosis Lesions without Gadolinium-Based Contrast Agent
- 2016
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Ingår i: American Journal of Neuroradiology. - : American Society of Neuroradiology (ASNR). - 0195-6108 .- 1936-959X. ; 37:1, s. 94-100
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Contrast-enhancing MS lesions are important markers of active inflammation in the diagnostic work-up of MS and in disease monitoring with MR imaging. Because intravenous contrast agents involve an expense and a potential risk of adverse events, it would be desirable to identify active lesions without using a contrast agent. The purpose of this study was to evaluate whether pre-contrast injection tissue-relaxation rates and proton density of MS lesions, by using a new quantitative MR imaging sequence, can identify active lesions.MATERIALS AND METHODS: Forty-four patients with a clinical suspicion of MS were studied. MR imaging with a standard clinical MS protocol and a quantitative MR imaging sequence was performed at inclusion (baseline) and after 1 year. ROIs were placed in MS lesions, classified as nonenhancing or enhancing. Longitudinal and transverse relaxation rates, as well as proton density were obtained from the quantitative MR imaging sequence. Statistical analyses of ROI values were performed by using a mixed linear model, logistic regression, and receiver operating characteristic analysis.RESULTS: Enhancing lesions had a significantly (P < .001) higher mean longitudinal relaxation rate (1.22 ± 0.36 versus 0.89 ± 0.24), a higher mean transverse relaxation rate (9.8 ± 2.6 versus 7.4 ± 1.9), and a lower mean proton density (77 ± 11.2 versus 90 ± 8.4) than nonenhancing lesions. An area under the receiver operating characteristic curve value of 0.832 was obtained.CONCLUSIONS: Contrast-enhancing MS lesions often have proton density and relaxation times that differ from those in nonenhancing lesions, with lower proton density and shorter relaxation times in enhancing lesions compared with nonenhancing lesions.
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| 28. |
- Blystad, Ida, 1972-, et al.
(författare)
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Quantitative MRI for analysis of peritumoral edema in malignant gliomas
- 2017
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose Damage to the blood-brain barrier with subsequent contrast enhancement is a hallmark of glioblastoma. Non-enhancing tumor invasion into the peritumoral edema is, however, not usually visible on conventional magnetic resonance imaging. New quantitative techniques using relaxometry offer additional information about tissue properties. The aim of this study was to evaluate longitudinal relaxation R-1, transverse relaxation R-2, and proton density in the peritumoral edema in a group of patients with malignant glioma before surgery to assess whether relaxometry can detect changes not visible on conventional images. Methods In a prospective study, 24 patients with suspected malignant glioma were examined before surgery. A standard MRI protocol was used with the addition of a quantitative MR method (MAGIC), which measured R-1, R-2, and proton density. The diagnosis of malignant glioma was confirmed after biopsy/surgery. In 19 patients synthetic MR images were then created from the MAGIC scan, and ROIs were placed in the peritumoral edema to obtain the quantitative values. Dynamic susceptibility contrast perfusion was used to obtain cerebral blood volume (rCBV) data of the peritumoral edema. Voxel-based statistical analysis was performed using a mixed linear model. Results R-1, R-2, and rCBV decrease with increasing distance from the contrast-enhancing part of the tumor. There is a significant increase in R1 gradient after contrast agent injection (P<.0001). There is a heterogeneous pattern of relaxation values in the peritumoral edema adjacent to the contrast-enhancing part of the tumor. Conclusion Quantitative analysis with relaxometry of peritumoral edema in malignant gliomas detects tissue changes not visualized on conventional MR images. The finding of decreasing R-1 and R-2 means shorter relaxation times closer to the tumor, which could reflect tumor invasion into the peritumoral edema. However, these findings need to be validated in the future.
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| 29. |
- Boeva, Veselka, Professor, et al.
(författare)
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Cluster Validation Measures for Label Noise Filtering
- 2018
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Ingår i: 9th International Conference on Intelligent Systems 2018: Theory, Research and Innovation in Applications, IS 2018 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538670972 ; , s. 109-116
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Konferensbidrag (refereegranskat)abstract
- Cluster validation measures are designed to find the partitioning that best fits the underlying data. In this paper, we show that these well-known and scientifically proven validation measures can also be used in a different context, i.e., for filtering mislabeled instances or class outliers prior to training in super-vised learning problems. A technique, entitled CVI-based Outlier Filtering, is proposed in which mislabeled instances are identified and eliminated from the training set, and a classification hypothesis is then built from the set of remaining instances. The proposed approach assigns each instance several cluster validation scores representing its potential of being an outlier with respect to the clustering properties the used validation measures assess. We examine CVI-based Outlier Filtering and compare it against the LOF detection method on ten data sets from the UCI data repository using five well-known learning algorithms and three different cluster validation indices. In addition, we study two approaches for filtering mislabeled instances: local and global. Our results show that for most learning algorithms and data sets, the proposed CVI-based outlier filtering algorithm outperforms the baseline method (LOF). The greatest increase in classification accuracy has been achieved by combining at least two of the used cluster validation indices and global filtering of mislabeled instances. © 2018 IEEE.
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| 30. |
- Eckeryd, Robert, 1972-
(författare)
-
Acceptans eller utstötning? : ogifta mödrar i Ångermanland 1860–1940
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation has investigated the social vulnerability of unmarried mothers in three rural court districts in the province of Ångermanland in northern Sweden during the period 1860–1940. The main focus is on the consequences that the birth of one or more illegitimate children had on the women’s lives as regards to how they were treated in the local community, including by both neighbours and formal institutions. It was pre-supposed that the social vulnerability of unmarried mothers can vary considerably between geographically close areas and that such variations are likely linked to the frequency of illegitimate births, which in turn should be dependent on unrelated variables such as diverging socio-economic structures and the importance of Christianity. Two periods have been chosen for in-depth analysis: the 1860s and a number of years before and after 1918, when the first specific law regarding illegitimate children was put into practice. This enables both a comparison of areas with diverging illegitimate fertility rates and a comparison of the unmarried mothers’ social vulnerability in a community still largely based on farming in the 19th century, with that of a more industrialised and modernised society in the early 20th century. Theories of social stigma and the concept of deviancy have been applied for the purposes of interpretation. Social vulnerability has been assumed to be linked to perceptions regarding how deviant the unmarried mothers were considered to be in the local community. To investigate this Church records have been used for life course analyses covering the women’s fertile ages, with a primary focus on the unmarried mothers’ marriage patterns. Court protocols have also been studied for an analysis of how paternity suits were handled by district courts, as regards what evidence was required for different outcomes and what that can tell us about the women’s social vulnerability. Based on the frequency of illegitimate births, two main hypotheses were formulated: first, that the unmarried mothers were least socially vulnerable in one particular area during both periods, and secondly that they during the 1860s were most vulnerable in a court district with an unusually low rate of illegitimate births. The first main hypothesis was confirmed regarding the 1860s. The second main hypothesis was however disproven by several factors. In the early 20th century, modernisation and the growing working class seem to have eased attitudes towards unmarried mothers in the two court districts with the lowest illegitimate fertility frequences, leading to a similar social vulnerability in all three areas. However an illegitimate birth could still be seen as deviant behavior and women who had been abandoned with two illegitimate children seems to have been stigmatised in all areas during both periods of investigation.
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| 31. |
- Eriksson, Daniel, et al.
(författare)
-
Health-related quality of life across all stages of autosomal dominant polycystic kidney disease
- 2017
-
Ingår i: Nephrology, Dialysis and Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 32:12, s. 2106-2111
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A limited number of studies have assessed health-related quality of life (HRQoL) in autosomal dominant polycystic kidney disease (ADPKD). Results to date have been conflicting and studies have generally focused on patients with later stages of the disease. This study aimed to assess HRQoL in ADPKD across all stages of the disease, from patients with early chronic kidney disease (CKD) to patients with end-stage renal disease.METHODS: A study involving cross-sectional patient-reported outcomes and retrospective clinical data was undertaken April-December 2014 in Denmark, Finland, Norway and Sweden. Patients were enrolled into four mutually exclusive stages of the disease: CKD stages 1-3; CKD stages 4-5; transplant recipients; and dialysis patients.RESULTS: Overall HRQoL was generally highest in patients with CKD stages 1-3, followed by transplant recipients, patients with CKD stages 4-5 and patients on dialysis. Progressive disease predominately had an impact on physical health, whereas mental health showed less variation between stages of the disease. A substantial loss in quality of life was observed as patients progressed to CKD stages 4-5.CONCLUSIONS: Later stages of ADPKD are associated with reduced physical health. The value of early treatment interventions that can delay progression of the disease should be considered.
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| 32. |
- Eriksson, Daniel, et al.
(författare)
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Real-world costs of autosomal dominant polycystic kidney disease in the Nordics
- 2017
-
Ingår i: BMC Health Services Research. - : Springer Science and Business Media LLC. - 1472-6963. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- Background: There is limited real-world data on the economic burden of patients with autosomal dominant polycystic kidney disease (ADPKD). The objective of this study was to estimate the annual direct and indirect costs of patients with ADPKD by severity of the disease: chronic kidney disease (CKD) stages 1-3; CKD stages 4-5; transplant recipients; and maintenance dialysis patients. Methods: A retrospective study of ADPKD patients was undertaken April-December 2014 in Denmark, Finland, Norway and Sweden. Data on medical resource utilisation were extracted from medical charts and patients were asked to complete a self-administered questionnaire. Results: A total of 266 patients were contacted, 243 (91%) of whom provided consent to participate in the study. Results showed that the economic burden of ADPKD was substantial at all levels of the disease. Lost wages due to reduced productivity were large in absolute terms across all disease strata. Mean total annual costs were highest in dialysis patients, driven by maintenance dialysis care, while the use of immunosuppressants was the main cost component for transplant care. Costs were twice as high in patients with CKD stages 4-5 compared to CKD stages 1-3. Conclusions: Costs associated with ADPKD are significant and the progression of the disease is associated with an increased frequency and intensity of medical resource utilisation. Interventions that can slow the progression of the disease have the potential to lead to substantial reductions in costs for the treatment of ADPKD.
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| 33. |
- Hamodi, Hussan, et al.
(författare)
-
Economic lifetime of a drilling machine: a case study on mining industry
- 2015
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Ingår i: International Journal of Strategic Engineering Asset Management (IJSEAM). - 1759-9733 .- 1759-9741. ; 2:2, s. 177-189
-
Tidskriftsartikel (refereegranskat)abstract
- Underground mines use many different types of machinery duringthe drift mining processes of drilling, charging, blasting, loading, scaling andbolting. Drilling machines play a critical role in the mineral extraction processand thus are important economically. However, as the machines age, theirefficiency and effectiveness decrease, negatively affecting productivity andprofitability and increasing total cost. Hence, the economic replacementlifetime of the machine is a key performance indicator. This paper introducesan optimisation model that gives the optimal lifetime for a drilling machine. Acase study has been done at an underground Swedish mine to identify theeconomic replacement time of a drilling machine. It considers the purchaseprice, maintenance and operation costs, and the machine’s second-hand value.Findings show that the economic replacement lifetime of a drilling machine inthis mine is 96 months. The proposed model can be used for other undergroundmining machines.
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| 34. |
- Hamodi, Hussan, et al.
(författare)
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Model for economic replacement time of mining production rigs including redundant rig costs
- 2015
-
Ingår i: Journal of Quality in Maintenance Engineering. - 1355-2511 .- 1758-7832. ; 21:2, s. 207-226
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose - This paper presents a practical model to determine the economic replacement time (ERT) of production machines. The objective is to minimise the total cost of capital equipment, where total cost includes acquisition, operating, maintenance costs and costs related to the machine’s downtime. The costs related to the machine’s downtime are represented by the costs of using a redundant machine. Design/methodology/approach - Four years of cost data are collected. Data is analysed, practical optimisation model is developed and regression analysis is done to estimate the drilling rigs ERT. The artificial neural network (ANN) technique is used to identify the effect of factors influencing the ERT of the drilling rigs.Findings - The results show that the redundant rig cost has the largest impact on ERT, followed by acquisition, maintenance and operating costs. The study also finds that increasing redundant costs per hour have a negative effect on ERT, while decreases in other costs have a positive effect. Regression analysis shows a linear relationship between the cost factors and ERT. Practical implications - The proposed approach can be used by the decision maker in determining the economic replacement time of production machines which used in mining industry.Originality/value - The research proposed in this paper provides and develops an optimisation model for economic replacement time of mining machines. This research also identifies and explains the factors that have the largest impact on the production machine’s ERT. This model for estimating the ERT has never been studied on mining drilling rigs.Keywords Decision support model, Life cycle cost, Optimisation, Replacement timePaper type Research paper
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| 35. |
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| 36. |
- Hamodi, Hussan, et al.
(författare)
-
Monte Carlo Reliability Simulation of Underground Mining Drilling Rig
- 2016
-
Ingår i: Current Trends in Reliability, Availability, Maintainability and Safety. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319235967 - 9783319235974 ; , s. 633-643
-
Konferensbidrag (refereegranskat)abstract
- Drilling rigs are widely used in mine development or construction and tunnel engineering projects. The rig consists of 12 subsystems in a series configuration and can be driven by diesel or electrical engines. This paper uses the Kamat-Riley (K-R) event-based Monte Carlo simulation method to perform reliability analysis of an underground mine drilling rig. For data analysis and to increase statistical accuracy, the paper discusses three case studies in an underground mine in Sweden. Researchers built a process to programme the simulation process and used MATLABTM software to run simulations. The results showed the simulation approach is applicable to the reliability analysis of this rig. Moreover, the reliability of all rigs reaches almost zero value after 50 h of operation. Finally, the differences between the reliability of the studied fleet of drilling rigs are a maximum 10 %. Therefore, all maintenance or spare part planning issues can be managed in a similar way
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| 37. |
- Hasib, Lekbira, et al.
(författare)
-
Functional and homeostatic defects of regulatory T cells in patients with coronary artery disease
- 2016
-
Ingår i: Journal of Internal Medicine. - : WILEY-BLACKWELL. - 0954-6820 .- 1365-2796. ; 279:1, s. 63-77
-
Tidskriftsartikel (refereegranskat)abstract
- ObjectiveRegulatory T cells (Tregs) are considered atheroprotective, and low levels have been associated with the acute coronary syndrome (ACS), particularly non-ST elevation (NSTE)-ACS. However, the functional properties as well as homeostasis of Tregs are mainly unknown in coronary artery disease (CAD). Here, we investigated the composition and functional properties of naive (n) and memory (m)Tregs in patients with NSTE-ACS and in patients 6-12months post-ACS. MethodsBased on the expression of CD25, FOXP3, CD127, CD45RA, CD39 and CTLA-4, Tregsubsets were defined by flow cytometry in whole blood or isolated CD4(+) T cells. The functional properties of nTregs and mTregs were examined in terms of proliferative capacity and modulation of cytokine secretion. To understand the potential consequences of Treg defects, we also investigated correlations with lipopolysaccharide (LPS)-induced cytokine secretion and ultrasound-defined carotid atherosclerosis. ResultsBoth NSTE-ACS and post-ACS patients exhibited reduced levels of nTregs (P<0.001) compared with healthy control subjects, but without compensatory increases in mTregs. Both nTregs and mTregs from patients showed significantly lower replicative rates and impaired capacity to modulate T-cell proliferation and secretion of interferon-gamma and IL-10. The Treg defect was also associated with LPS-induced cytokine secretion and increased burden of carotid atherosclerosis. ConclusionOur results demonstrate a functional and homeostatic Treg defect in patients with NSTE-ACS and also in stabilized patients 6-12months after ACS. Moreover, this defect was associated with a subclinical proinflammatory and atherogenic state. We believe that the failure to preserve Treg function and homeostasis reflects a need for immune-restoring strategies in CAD.
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| 38. |
- Hilmersson, Mikael, et al.
(författare)
-
Serendipitous Opportunities, Entrepreneurial Logic and Knowledge in International Business Networks
- 2016
-
Konferensbidrag (refereegranskat)abstract
- Few researchers and even fewer practitioners would deny that luck, chance or serendipitous events play a central role in the growth process of firms. However, most entrepreneurship models ignore the role of serendipity in the opportunity discovery process. Instead, it is assumed that international opportunities are discovered or created by entrepreneurs. In this paper we provide a more nuanced view on international opportunities by developing the role of serendipitous opportunities in the internationalization process. We develop a model integrating the notions of serendipity, entrepreneurial logic, experiential knowledge and network knowledge redundancy. From our model we condense three sets of hypotheses on the relationships among experiential knowledge and entrepreneurial logic, network knowledge redundancy and entrepreneurial logic, and entrepreneurial logic and serendipity. We confront our hypotheses with data collected on-site at 160 firms covering 226 opportunities. The result of our analysis reveals that experiential knowledge and network knowledge redundancy both lead to a more causation-based logic of the firm. Causation in turn reduces the likeliness that serendipitous opportunities will be realized in the internationalization process. These findings come with implications for both researchers and practitioners.
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| 39. |
- Håkansson, Irene, et al.
(författare)
-
Neurofilament levels, disease activity and brain volume during follow-up in multiple sclerosis
- 2018
-
Ingår i: Journal of Neuroinflammation. - : BMC. - 1742-2094. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Background: There is a need for clinically useful biomarkers of disease activity in clinically isolated syndrome (CIS) and relapsing remitting MS (RRMS). The aim of this study was to assess the correlation between neurofilament light chain (NFL) in cerebrospinal fluid (CSF) and serum and the relationship between NFL and other biomarkers, subsequent disease activity, and brain volume loss in CIS and RRMS. Methods: A panel of neurodegenerative and neuroinflammatory markers were analyzed in repeated CSF samples from 41 patients with CIS or RRMS in a prospective longitudinal cohort study and from 22 healthy controls. NFL in serum was analyzed using a single-molecule array (Simoa) method. "No evidence of disease activity-3" (NEDA-3) status and brain volume (brain parenchymal fraction calculated using SyMRI (R)) were recorded during 4 years of follow-up. Results: NFL levels in CSF and serum correlated significantly (all samples, n = 63, r 0.74, p amp;lt; 0.001), but CSF-NFL showed an overall stronger association profile with NEDA-3 status, new T2 lesions, and brain volume loss. CSF-NFL was associated with both new T2 lesions and brain volume loss during follow-up, whereas CSF-CHI3L1 was associated mainly with brain volume loss and CXCL1, CXCL10, CXCL13, CCL22, and MMP-9 were associated mainly with new T2 lesions. Conclusions: Serum and CSF levels of NFL correlate, but CSF-NFL predicts and reflects disease activity better than S-NFL. CSF-NFL levels are associated with both new T2 lesions and brain volume loss. Our findings further add to the accumulating evidence that CSF-NFL is a clinically useful biomarker in CIS and RRMS and should be considered in the expanding NEDA concept. CSF-CXCL10 and CSF-CSF-CHI3L1 are potential markers of disease activity and brain volume loss, respectively.
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| 40. |
- Håkansson, Irene, et al.
(författare)
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Neurofilament light chain in cerebrospinal fluid and prediction of disease activity in clinically isolated syndrome and relapsing-remitting multiple sclerosis
- 2017
-
Ingår i: European Journal of Neurology. - : Wiley. - 1351-5101 .- 1468-1331. ; 24:5, s. 703-712
-
Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Improved biomarkers are needed to facilitate clinical decision-making and as surrogate endpoints in clinical trials in multiple sclerosis (MS). We assessed whether neurodegenerative and neuroinflammatory markers in cerebrospinal fluid (CSF) at initial sampling could predict disease activity during 2 years of follow-up in patients with clinically isolated syndrome (CIS) and relapsing-remitting MS. Methods: Using multiplex bead array and enzyme-linked immunosorbent assay, CXCL1, CXCL8, CXCL10, CXCL13, CCL20, CCL22, neurofilament light chain (NFL), neurofilament heavy chain, glial fibrillary acidic protein, chitinase-3-like-1, matrix metalloproteinase-9 and osteopontin were analysed in CSF from 41 patients with CIS or relapsing-remitting MS and 22 healthy controls. Disease activity (relapses, magnetic resonance imaging activity or disability worsening) in patients was recorded during 2 years of follow-up in this prospective longitudinal cohort study. Results: In a logistic regression analysis model, NFL in CSF at baseline emerged as the best predictive marker, correctly classifying 93% of patients who showed evidence of disease activity during 2 years of follow-up and 67% of patients who did not, with an overall proportion of 85% (33 of 39 patients) correctly classified. Combining NFL with either neurofilament heavy chain or osteopontin resulted in 87% overall correctly classified patients, whereas combining NFL with a chemokine did not improve results. Conclusions: This study demonstrates the potential prognostic value of NFL in baseline CSF in CIS and relapsing-remitting MS and supports its use as a predictive biomarker of disease activity.
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| 41. |
- Johansson, Linda, et al.
(författare)
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Concentration of antibodies against Porphyromonas gingivalis is increased before the onset of symptoms of rheumatoid arthritis
- 2016
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Ingår i: Arthritis Research & Therapy. - : BioMed Central. - 1478-6362. ; 18
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The periodontal pathogen Porphyromonas gingivalis is hypothesized to be important in rheumatoid arthritis (RA) aetiology by inducing production of anti-citrullinated protein antibodies (ACPA). We have shown that ACPA precede RA onset by years, and that anti-P. gingivalis antibody levels are elevated in RA patients. The aim of this study was to investigate whether anti-P. gingivalis antibodies pre-date symptom onset and ACPA production. Methods: A case-control study (251 cases, 198 controls) was performed within the Biobank of Northern Sweden. Cases had donated blood samples (n = 422) before the onset of RA symptoms by 5.2 (6.2) years (median (interquartile range)). Blood was also collected from 192 RA patients following diagnosis. Antibodies against P. gingivalis virulence factor arginine gingipainB (RgpB), and a citrullinated peptide (CPP3) derived from the P. gingivalis peptidylarginine deiminase enzyme, were analysed by ELISA. Results: Anti-RgpB IgG levels were significantly increased in pre-symptomatic individuals (mean +/- SEM; 152.7 +/- 14.8 AU/ml) and in RA patients (114.4 +/- 16.9 AU/ml), compared with controls (p < 0.001). Anti-CPP3 antibodies were detected in 5 % of pre-symptomatic individuals and in 8 % of RA patients, with elevated levels in both subsets (4.33 +/- 0.59 and 9.29 +/- 1.81 AU/ml, respectively) compared with controls (p < 0.001). Anti-CPP3 antibodies followed the ACPA response, with increasing concentrations over time, whilst anti-RgpB antibodies were elevated and stable in the pre-symptomatic individuals with a trend towards lower levels after RA diagnosis. Conclusions: Anti-P. gingivalis antibody concentrations were significantly increased in RA patients compared with controls, and were detectable years before onset of symptoms of RA, supporting an aetiological role for P. gingivalis in the development of RA.
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| 42. |
- Jonsson, Per, et al.
(författare)
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Formation of Blood Foam in the Air Trap During Hemodialysis Due to Insufficient Automatic Priming of Dialyzers
- 2018
-
Ingår i: Artificial Organs. - : Wiley. - 0160-564X .- 1525-1594. ; 42:5, s. 533-539
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Tidskriftsartikel (refereegranskat)abstract
- We were encouraged to investigate the reasons for large amounts of foam observed in bloodlines during hemodialysis (HD). Foam was visible in the venous air trap within the Artis Gambro dialysis device. Estimates of the extent of foam were graded (0no foam, 10extensive foam) by two persons that were blind to the type of dialyzer used. Thirty-seven patients were involved in the dialysis procedures. Consecutive dialyses were graded using dialyzers from Fresenius Medical Care (CorDiax dialyzers that were used for high flux HDFX80 and FX100, and for hemodiafiltrationFX1000). The extracorporeal circuit was primed automatically by dialysate using Gambro Artis software 8.15 006 (Gambro, Dasco, Medolla Italy, Baxter, Chicago, IL, USA). The priming volume recommended by the manufacturer was 1100 mL, whereas our center uses 1500 mL. Extensive amounts of blood foam were visual in the air traps. Although the manufacturer recommended extension of priming volume up to 3000 mL, this did not eliminate the foam. Microbubble measurement during HD revealed the air to derive from the dialyzers. When changing to PF210H dialyzers (Baxter) and using a priming volume of 1500 mL, the foam was significantly less (P<0.01). The extent of foam correlated with the size of the FX-dialyzer surface (P=0.002). The auto-priming program was updated to version 8.21 by the manufacturer and the extent of foam in the air trap using FX dialyzers was now reduced and there was no longer a difference between FX and PF dialyzers, although less foam was still visible in the venous air trap during several dialyses. In conclusion, this study urgently calls attention to blood foam development in the venous air trap when using Artis devices and priming software 8.15 in combination with Fresenius dialyzers. Updated auto-priming software (version 8.21) of Artis should be requested to reduce the extent of foam for the Fresenius dialyzers. Other interactions may also be present. We recommend further studies to clarify these problems. Meanwhile caution is warranted for the combined use of dialysis devices and dialyzers with incompatible automatic priming.
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| 43. |
- Jönsson, Jens, et al.
(författare)
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Measurement of vertical geometry variations in railway turnouts exposed to different operating conditions
- 2016
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 230:2, s. 486-501
-
Tidskriftsartikel (refereegranskat)abstract
- Turnouts are critical units in a railway system; they perform the switching procedure that allows trains to change between routes. Monitoring the track geometry of a turnout is necessary for maintenance planning and design optimisation. Monitoring is usually done by track recording cars, however, to isolate the ageing and dynamic behaviour of the track it is also necessary to study the unstressed track geometry of the turnouts. Such measurements can be used to develop degradation models to optimise maintenance and design, thereby increasing availability and reducing life cycle cost. This paper introduces a new method to measure the vertical position of the track geometry over time during non-operational conditions (unstressed) to show track degradation. The new method includes a smart system that uses relative measurement reference points to create a better accuracy and lower costs compared with fixed reference points. It evaluates various types of measurement equipment and uses levelling equipment to measure the unstressed vertical geometry of 13 turnouts located on Swedish railway lines, with three follow-up measurements over a year and a half. The turnouts were categorised into four groups: based on their accumulated capacity in million gross tonnes (MGT) and whether they were on a straight or curved main track. Surprisingly, the first three measurements showed the geometry of turnouts on the straight main track to have a vertical elevation tendency towards the mid-section, whereas the turnouts on the curved main track had a general vertical downwards bend tendency towards the mid-section. The results also showed that a higher capacity in MGT has a greater influence on track geometry changes over time.
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| 44. |
- Keller, Jan, et al.
(författare)
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Effect of Cu content on post‐sulfurization of Cu(In,Ga)Se2 films and corresponding solar cell performance
- 2019
-
Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 216:20
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, the effect of the initial copper content of co‐evaporated Cu(In1−x,Gax)Se2 (CIGS) absorber films on the impact of a post‐annealing step in elemental sulfur atmosphere is studied. The Cu concentration is varied over a wide range ([Cu]/[III] = CGI = 0.57–1.23), allowing to identify composition‐dependent trends in phase formation, chemical rearrangements, and solar cell performance after sulfurization. For all samples, a ternary CuInS2 layer forms at the surface. In addition, sulfur 1) is incorporated in randomly distributed CuIn(S,Se)2 mixed crystals underneath CuInS2; 2) diffuses into multidimensional defects (e.g., dislocations and grain boundaries); and 3) is bound in Na–In–S surface plates. It is found that Cu‐poor absorber composition (CGI ≤ 0.82) favors CuInS2 growth as compared with close‐stoichiometric CIGS films, driven by a faster diffusion of Cu toward the surface. For Cu‐rich absorbers (CGI > 1), Se—S exchange is significantly accelerated, presumably by the presence of Cu2−xSe phases reacting to Cu2−xS and eventually catalyzing CuInS2 formation. Finally, open‐circuit voltage (VOC), fill factor (FF), and efficiency (η) of corresponding solar cells increase after sulfurization with increasing CGI until stoichiometry is reached. The result is explained by a mitigated Cu depletion of the absorber bulk after sulfurization for close‐stoichiometric CIGS.
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| 45. |
- Khan, Saad Ahmed, 1987-, et al.
(författare)
-
Carry distance of top-of-rail friction modifiers
- 2018
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : Sage Publications. - 0954-4097 .- 2041-3017. ; 232:10, s. 2418-2430
-
Tidskriftsartikel (refereegranskat)abstract
- Rail issues such as corrugation, rolling contact fatigue, noise and wear have been increasing with the increase in railway traffic. The application of top-of-rail friction modifiers (TOR-FMs) is claimed by their manufacturers in the railway industry to be a well-established technique for resolving the above-mentioned issues. There are various methods for applying friction modifiers at the wheel–rail interface, among which stationary wayside systems are recommended by TOR-FM manufacturers when a distance of a few kilometres is to be covered. TOR-FM manufacturers also claim that by using wayside equipment, the TOR-FM can be spread over a minimum distance of 3 km, over which it maintains a coefficient of friction of µ = 0.35 ± 0.05. To determine the carry distance of TOR-FMs, some researchers use tribometers to measure the coefficients of friction. However, moisture and deposits from the environment and trains can alter the top-of-rail friction and give a misleading indication of the presence of a friction modifier. Therefore, the coefficient of friction itself is not a clear indicator of the presence of TOR-FMs. In the present study, cotton swabs dipped in a mixture of alcohol and ester were used to collect surface deposits (a third body) from both the wheel and rail at various distances from the point of application. Subsequently, the third body collected on the cotton swab was analysed using an energy dispersive X-ray analysis. The results have shown that the maximum carry distance of TOR-FMs on the top of the rail is limited to 70 m when using a TOR-FM from one manufacturer and to 450 m when using a TOR-FM from another manufacturer. The carry distance on the contact band of the wheel is limited to 100 m and 340 m. The friction modifier on the edges of the contact band was detected over a distance of up to 3 km; however, this will not minimise the damage or friction at the wheel–rail interface.
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| 46. |
- Khan, Saad Ahmed, 1987-
(författare)
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Effects of top-of-rail friction modifiers on the friction, wear and cracks of railway rails
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The railway is an economical and environmentally friendly mode of transport for long distances and heavy loads. The demands on the operators are increasing with increased competition in the market, and therefore they are currently demanding more track capacity. In the short term, the existing network is expected to deliver the increased capacity. In order to achieve increased capacity without introducing double track, either the axle load or the number of trains (i.e. the annual gross tonnage) needs to be increased, which will decrease the life of the rail and thus increase the maintenance cost. To increase the lifetime of the rails without compromising with regard to the axle load and speed, one must increase the strength of the rails, decrease the traction forces between the rails and wheels, or introduce a third body with anti-wear and anti-crack properties that can reduce the wear and rolling contact fatigue (RCF) without reducing the traction forces below the safety limit.The traction forces depend on several variables, for example third bodies in the wheel-rail interface, the train dynamics, the wheel and rail profiles, etc. Third bodies in the wheel-rail interface are one of the important influencing factors. The additive third bodies with anti-wear properties and friction reduction capabilities reduces both the wear and the RCF. However, a friction coefficient in the wheel tread and the top of the rail below 0.3 can cause slippage and a long braking distance. To reduce the degree of utilised friction to a value close to 0.35 from dry conditions with a value of 0.55, and thereby reduce the wear, a product known as top-of-rail friction modifier (TOR-FM) was developed in North America and presented in 2003 at the heavy haul conference. The TOR-FM manufacturers claim that their products provide a fixed range of friction coefficients (μ) and Kalker’s coefficients in the wheel-rail interface. Kalker’s coefficient considers the tendency of creepage between the rail and wheel as a function of the traction forces at lower creepage levels. Field and laboratory tests in the USA, Canada and China have determined the benefits of using friction control products, which include the reduction of RCF, wear, corrugation, bogie hunting, noise, and fuel consumption without any side effects. In contrast, researchers at Luleå University of Technology (LTU) have found that such products in certain conditions give unacceptably low friction that can cause long braking distances and slippage. Initial measurements performed using a wayside TOR-FM system on the Iron Ore Line (IOL – “Malmbanan” in Swedish) could not find any benefits of implementing such systems.Trafikverket is considering the implementation of the TOR-FM technology on the IOL. Directly implementing such technology can be inappropriate and expensive, because the reliability of a TOR-FM system has never been assessed for the conditions of the IOL. The IOL is the northernmost railway line in Sweden and is experiencing the problem of RCF, especially on its curves. This railway line is a single track and is mainly utilised by the ore freight trains operated by the Swedish mining company LKAB. The freight trains run by LKAB have an axle load of 30 tonnes, which is the heaviest in Europe. At present LKAB is planning to increase the axle load of their heavy haul trains to 32.5 tonnes, which will increase the RCF and wear issues.The present research investigated the effects of TOR-FMs using computer-based simulations, laboratory tests and field tests. The results from all the tests and simulations were used to calculate the life cycle cost of wayside and on-board systems. The simulation results have shown that by reducing the friction, the RCF can be reduced. This reduction in the RCF is greater on narrow curves than on larger curves as the traction forces decrease with an increase in the curve radius. Curves with a radius larger than m are not prone to RCF. The damage index method used in the simulation has also shown that on circular curves with a radius smaller than 300 m, the so-called “magic wear” rate can be achieved. Magic wear means that the wear rate due to normal operation is equal to the crack generation rate. The field results obtained using a handheld tribometer have shown that by using a TOR-FM, both the wear and the friction coefficients can be reduced. The content of the TOR-FM can have a significant effect on the carry distance and, generally, non-drying FMs have a longer carry distance. Excessive use of TOR-FM may cause unacceptably low friction and a high operational cost, and only result in an insignificant increase in the carry distance. In addition, it was also concluded that in the case of the wayside system during extreme winters, the equipment could have maintenance issues and thus a high operational cost. The on-board system is an economical alternative to the wayside system, as it has lower operation and maintenance costs. The results have also shown that snow and ice formation in the winter act as a lubricant. However, further investigations are needed to provide knowledge of the efficiency of such natural lubricants and their retention on the rail. The present research has taken the IOL as a case study, but the results will be applicable all over the world.
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| 47. |
- Khan, Saad Ahmed, 1987-, et al.
(författare)
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Prediction of the effects of friction control on top-of-rail cracks
- 2018
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : Sage Publications. - 0954-4097 .- 2041-3017. ; 232:2, s. 484-494
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Tidskriftsartikel (refereegranskat)abstract
- Rolling contact fatigue is a major problem connected with railway tracks, especially in curves, since it leads to highermaintenance costs. By optimising the top-of-rail friction, the wear and cracks on the top of the rail can eventually bereduced without causing very long braking distances. There are several research articles available on crack prediction,but most of the research is focused either on rail without a friction modifier or on wheels with and without frictioncontrol. In the present study, in order to predict the formation of surface-initiated rolling contact fatigue, a range offriction coefficients with different Kalker’s reduction factors has been assumed. Kalker’s reduction factor takes care ofthe basic tendency of creepage as a function of the traction forces at lower creepage. The assumed range covers possiblefriction values from those for non-lubricated rail to those for rail with a minimum measured friction control on the top ofthe rail using a friction modifier. A fatigue index model based on the shakedown theory was used to predict thegeneration of surface-initiated rolling contact fatigue. Simulations were performed using multi-body simulation, forwhich inputs were taken from the Iron Ore line in the north of Sweden. The effect of friction control was studiedfor different curve radii, ranging from 200 m to 3000 m, and for different axle loads from 30 to 40 tonnes at a constanttrain speed of 60 km/h. One example of a result is that a maximum friction coefficient (m) of 0.2 with a Kalker’s reductionfactor of 15% is needed in the case of trains with a heavy axle load to avoid crack formation.
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| 48. |
- Khan, Saad Ahmed, 1987-, et al.
(författare)
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Prediction of top-of-rail friction control effects on rail RCF suppressed by wear
- 2017
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Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 380-381, s. 106-114
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Tidskriftsartikel (refereegranskat)abstract
- Rolling contact fatigue (RCF) and wear, two major deterioration processes, limit the lifetime of rails. These deterioration processes are even more severe on the curves of tracks used by heavy haul trains. Because wear is a material removing process, it can suppress the formation of RCF (also known as surface initiated cracks). In railways, cracks have a higher risk of instigating a catastrophic failure than wear; hence, it is comparatively better to have wear than to have cracks. By controlling the top-of-rail friction, both of these deteriorating processes can be reduced to enhance the lifetime of rails. In order to achieve these possible advantages, the infrastructure manager of the Swedish railway is planning to implement a top-of-rail friction control technology on the iron ore line in northern Sweden wherein RCF is a major problem on the curves. The present study uses a damage index model in a multi-body simulation software and predicts the probability of RCF formation with suppressing effect of wear for different friction control values. The effect of friction control is simulated on curve radii ranging from 200 to 3,000 m and axle loads ranging from 30 to 40 t at a constant train speed of 60 km/h. Findings show that on a very sharp circular curve, radius < 300 m, RCF can be eliminated without friction control due to the high wear rate. On moderate curves, 300 < radius < 1,000 m, a friction coefficient (µ) of, at most, 0.3 with a Kalker's coefficient of, at most, 30% is required to avoid RCF
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| 49. |
- Kubin, Markus, et al.
(författare)
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Cr L-Edge X-ray Absorption Spectroscopy of CrIII(acac)3 in Solution with Measured and Calculated Absolute Absorption Cross Sections
- 2018
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:29, s. 7375-7384
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption spectroscopy at the L-edge of 3d transition metals is widely used for probing the valence electronic structure at the metal site via 2p–3d transitions. Assessing the information contained in L-edge absorption spectra requires systematic comparison of experiment and theory. We here investigate the Cr L-edge absorption spectrum of high-spin chromium acetylacetonate CrIII(acac)3 in solution. Using a transmission flatjet enables determining absolute absorption cross sections and spectra free from X-ray-induced sample damage. We address the challenges of measuring Cr L absorption edges spectrally close to the O K absorption edge of the solvent. We critically assess how experimental absorption cross sections can be used to extract information on the electronic structure of the studied system by comparing our results of this CrIII (3d3) complex to our previous work on L-edge absorption cross sections of MnIII(acac)3 (3d4) and MnII(acac)2 (3d5). Considering our experimental uncertainties, the most insightful experimental observable for this d3(CrIII)–d4(MnIII)–d5(MnII) series is the L-edge branching ratio, and we discuss it in comparison to semiempirical multiplet theory and ab initio restricted active space calculations. We further discuss and analyze trends in integrated absorption cross sections and correlate the spectral shapes with the local electronic structure at the metal sites.
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| 50. |
- Kubin, Markus, et al.
(författare)
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Direct Determination of Absolute Absorption Cross Sections at the L-Edge of Dilute Mn Complexes in Solution Using a Transmission Flatjet
- 2018
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Ingår i: Inorganic Chemistry. - : AMER CHEMICAL SOC. - 0020-1669 .- 1520-510X. ; 57:9, s. 5449-5462
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Tidskriftsartikel (refereegranskat)abstract
- The 3d transition metals play a pivotal role in many charge transfer processes in catalysis and biology. X-ray absorption spectroscopy at the L-edge of metal sites probes metal 2p–3d excitations, providing key access to their valence electronic structure, which is crucial for understanding these processes. We report L-edge absorption spectra of MnII(acac)2 and MnIII(acac)3 complexes in solution, utilizing a liquid flatjet for X-ray absorption spectroscopy in transmission mode. With this, we derive absolute absorption cross-sections for the L-edge transitions with peak magnitudes as large as 12 and 9 Mb for MnII(acac)2 and MnIII(acac)3, respectively. We provide insight into the electronic structure with ab initio restricted active space calculations of these L-edge transitions, reproducing the experimental spectra with excellent agreement in terms of shapes, relative energies, and relative intensities for the two complexes. Crystal field multiplet theory is used to assign spectral features in terms of the electronic structure. Comparison to charge transfer multiplet calculations reveals the importance of charge transfer in the core-excited final states. On the basis of our experimental observations, we extrapolate the feasibility of 3d transition metal L-edge absorption spectroscopy using the liquid flatjet approach in probing highly dilute biological solution samples and possible extensions to table-top soft X-ray sources.
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