| 1. |
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| 2. |
- Andersson, Arne, et al.
(författare)
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Direct Propane Ammoxidation to Acrylonitrile: Kinetics and Nature of the Active Phase
- 1993
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Ingår i: New Frontiers in Catalysis (Studies in Surface Science and Catalysis ). - 0167-2991. ; 75, s. 691-705
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Konferensbidrag (refereegranskat)abstract
- The kinetics of the direct synthesis of acrylonitrile from propane on V-Sb-Al-(W) mixed oxides indicate that acrylonitrile (ACN) forms by two parallel pathways, one directly from propane and the second, which is the prevalent path, through the intermediate formation of propylene (C3=). The limiting factor in the formation of ACN is the relative slowness of the step of allylic oxidation to ACN of the intermediate C3=, and the higher rate of C3= oxidation to carbon oxides as compared to that of ACN to COx. The step of C3= oxidation to ACN is controlled by the surface availability of NH3 which, in turn, depends considerably on the side reaction of NH3 oxidation to N2. The catalytic behavior of different modified V-Sb-(Al)-O systems and their characterization by X-ray diffraction analysis and Raman, Infrared and X-ray Photoelectron spectroscopies indicate that i) a reduction of both V and Sb occurs during the catalytic reaction, ii) the presence of vanadium not stabilized in the rutile-like phase is responsible for the side reaction of NH3 oxidation and lowering of the selectivity, iii) alumina reacts with antimony forming an AlSbO4 rutile phase which could be epitaxially intergrown or in solid solution with the VSbO4/Sb2O4 system, which, in turn, limits the presence of not stabilized (unselective) vanadium species, and iv) antimony oxide supported on alumina is also selective in propane ammoxidation, but forming acetonitrile as the main product. The doping with vanadium of this sample increases slightly the activity, but especially gives rise to the formation of acrylonitrile instead of acetonitrile.
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| 3. |
- Andersson, Arne, et al.
(författare)
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Surface Characterization and Reactivity in Ammoxidation Reactions of Vanadium Antimonate Catalysts
- 1994
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Ingår i: Applied Catalysis A: General. - 0926-860X. ; 113:1, s. 43-57
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Tidskriftsartikel (refereegranskat)abstract
- Unsupported vanadium antimonate catalysts with Sb/V ratios of 1 and 5 and samples with the latter ratio supported on alumina were studied in toluene and propane ammoxidation to benzonitrile and acrylonitrile, respectively, and were characterized by X-ray photoelectron spectroscopy (XPS) analysis before and after catalytic tests. Activity data for toluene ammoxidation suggest that excess antimony with respect to the stoichiometric amount required for forming the VSbO4 rutile phase affects the dispersion of the latter phase giving smaller particles. Vanadium sites are involved both in the activation of toluene and in the insertion of nitrogen in this reaction, whereas antimony does not play a specific role in the reaction mechanism. In propane ammoxidation, on the other hand, due to a higher reaction temperature with respect to toluene (500°C vs. 370°C), free vanadia on the surface of the catalyst has a negative influence on the selectivity because it promotes the conversion of ammonia to nitrogen, decreasing the surface nitrogenous species required for the selective formation of acrylonitrile. Excess antimony is thus necessary for completing the reaction between antimony and vanadium oxides, but antimony also participates in the reaction mechanism. In propane ammoxidation, in fact, XPS data show that both vanadium and antimony sites are reduced. Tentatively, vanadium sites are involved in the activation of propane, while antimony sites insert nitrogen. The differences between the toluene and propane ammoxidation mechanisms are interpreted to be primarily related to the different reaction temperatures.
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| 4. |
- Andersson, John Åke, et al.
(författare)
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Sweden's Economic Relationships with Uganda
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This explorative study aims to map commercial and other economic relations between Sweden and Uganda during the years 2000-2014. In addition, we will discuss whether and how these relations may be related to Swedish bilateral aid.
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| 5. |
- Baranowska Körberg, Izabella, et al.
(författare)
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A Simple Repeat Polymorphism in the MITF-M Promoter Is a Key Regulator of White Spotting in Dogs
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:8, s. e104363-
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Tidskriftsartikel (refereegranskat)abstract
- The white spotting locus (S) in dogs is colocalized with the MITF (microphtalmia-associated transcription factor) gene. The phenotypic effects of the four S alleles range from solid colour (S) to extreme white spotting (s(w)). We have investigated four candidate mutations associated with the s(w) allele, a SINE insertion, a SNP at a conserved site and a simple repeat polymorphism all associated with the MITF-M promoter as well as a 12 base pair deletion in exon 1B. The variants associated with white spotting at all four loci were also found among wolves and we conclude that none of these could be a sole causal mutation, at least not for extreme white spotting. We propose that the three canine white spotting alleles are not caused by three independent mutations but represent haplotype effects due to different combinations of causal polymorphisms. The simple repeat polymorphism showed extensive diversity both in dogs and wolves, and allele-sharing was common between wolves and white spotted dogs but was non-existent between solid and spotted dogs as well as between wolves and solid dogs. This finding was unexpected as Solid is assumed to be the wild-type allele. The data indicate that the simple repeat polymorphism has been a target for selection during dog domestication and breed formation. We also evaluated the significance of the three MITF-M associated polymorphisms with a Luciferase assay, and found conclusive evidence that the simple repeat polymorphism affects promoter activity. Three alleles associated with white spotting gave consistently lower promoter activity compared with the allele associated with solid colour. We propose that the simple repeat polymorphism affects cooperativity between transcription factors binding on either flanking sides of the repeat. Thus, both genetic and functional evidence show that the simple repeat polymorphism is a key regulator of white spotting in dogs.
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| 6. |
- Huuhtanen, Jane, et al.
(författare)
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Catalytic and Spectroscopic Studies of Vanadium Oxide Supported on Group IVb and Vb Metal Oxides for Oxidation of Toluene
- 1993
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Ingår i: Applied Catalysis A: General. - 0926-860X. ; 97:2, s. 197-221
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Tidskriftsartikel (refereegranskat)abstract
- Vanadia was deposited on TiO2, ZrO2, HfO2, Nb2O5, and Ta2O5 supports using impregnation with either an oxalic acid solution of NH4VO3 or a solution of vanadyl acetylacetonate in ethanol. Prepared samples, with a nominal vanadia content in the range 0.5–2 monolayers, were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman and infrared spectroscopy, and were used in toluene oxidation. XRD did not reveal formation of any vanadia phase. XPS spectra showed deposited vanadium to be present mainly as V5+ on all the supports. A plot of the V:( support metal) ratio determined by XPS showed agglomeration of vanadia on TiO2, ZrO2, HfO2, and Nb2O5 to occur at loadings above 0.5 monolayer, while for Ta2O5 the dispersion seemed independent of the loading. Preparations from vanadyl acetylacetonate gave superior dispersion. Raman spectra showed bands from crystalline V2O5 on all the supports except Nb2O5. Raman and infrared bands from dispersed vanadia were present in the spectra of TiO2 (three species), ZrO2 and HfO2 (both one species) supported catalysts. No bands from vanadium-oxygen vibrational modes were seen in the spectra of Nb2O5 supported samples, but a V-OH band was observed, suggesting an amorphous structure. Some evidence was obtained for formation of amorphous VTa9O25 on Ta205. The activity for toluene oxidation increased with vanadia loading for each support, and the activity varied with respect to support at all loadings in the order TiO2 > ZrO2 > Nb2O5 > HfO2 > Ta2O5. The selectivity for formation of benzaldehyde was the highest using TiO2 and Nb2O5 supports, while for benzoic acid TiO2 was the best support.
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| 7. |
- Lundgren, Marcus, et al.
(författare)
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Lift-Off Lengths in an Optical Heavy-Duty Engine Operated at High Load with Low and High Octane Number Fuels
- 2018
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2018-April
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the ignition quality of diesel-and gasoline-like fuels on the lift-off length of the jet were investigated in an optical heavy duty engine. The engine was operated at a load of 22 bar IMEPg and 1200 rpm. A production type injector with standard holes were used. The lift-off length was recorded with high speed video Different injection pressures and inlet temperatures were used to affect conditions that consequently affect the lift-off length. No matter which fuel used nor injection pressure or inlet temperature, all lift-off lengths showed equal or close to equal lift-off length when stabilized. The higher octane fuel had a longer ignition delay and therefore the fuel penetrate the combustion chamber before auto ignition. This gave a longer lift-off length at the initial stage of combustion before reaching the same stabilized lift-off length. These results indicate that the hot combustion gases are a dominant factor to the lift-off length. Also, that possible soot reductions using high octanes fuels are feasible because of a longer ignition delay that allow more premixing, and an initially longer lift-off length due to longer penetration into the combustion chamber.
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| 8. |
- Lundgren, Marcus Olof, et al.
(författare)
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Effects of Post-Injections Strategies on UHC and CO at Gasoline PPC Conditions in a Heavy-Duty Optical Engine
- 2017
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2017:March
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Tidskriftsartikel (refereegranskat)abstract
- Gasoline partially premixed combustion (PPC) has shown potential in terms of high efficiency with low emissions of oxides of nitrogen (NOx) and soot. Despite these benefits, emissions of unburned hydrocarbons (UHC) and carbon monoxide (CO) are the main shortcomings of the concept. These are caused, among other things, by overlean zones near the injector tip and injector dribble. Previous diesel low temperature combustion (LTC) research has demonstrated post injections to be an effective strategy to mitigate these emissions. The main objective of this work is to investigate the impact of post injections on CO and UHC emissions in a quiescent (non-swirling) combustion system. A blend of primary reference fuels, PRF87, having properties similar to US pump gasoline was used at PPC conditions in a heavy duty optical engine. The start of the main injection was maintained constant. Dwell and mass repartition between the main and post injections were varied to evaluate their effect. All points were run at 7 bar IMEPg. High-speed imaging of the natural combustion luminescence was performed together with measurements of performance and engine out emissions. Results show reduction in both CO and UHC with close coupled injections. A large close coupled post injection show the largest reduction in UHC. Analysis show that a post injection prior to combustion reduces the dribble and increases the recirculation in the downstream region of the fuel jet, hence reaching more of the UHC in the area near the injector. General observations show that the partition of fuel between the injections have the largest impact on the CO while the dwell time affects UHC emissions. Injector dribble seems to be a significant contributor to the UHC emissions.
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| 9. |
- Lundgren, Marcus, et al.
(författare)
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Optical study on combustion transition from HCCI to PPC with gasoline compression ignition in a HD engine
- 2016. - April
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Ingår i: SAE 2016 World Congress and Exhibition. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. ; 2016-April
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Konferensbidrag (refereegranskat)abstract
- The partially premixed combustion (PPC) concept has shown high efficiency with low soot emissions. However, the in-cylinder phenomena are still to be explained and evaluated for further progress in the research. This work studies the start of combustion process during a transition from homogenous charge compression ignition (HCCI) to PPC. The process is visualized using a heavy-duty, non-swirling engine modified for optical access. High speed video was used to capture the natural luminosity of the combustion. The fuel used was PRF87. Single and double injection strategies were used at a load kept to the moderate level of 7.5 bar IMEPg. Single injections were swept from early HCCI to retarded PPC conditions whilst running a cycle to cycle temperature sweep, to capture the effect of injection timing and temperature differences simultaneously. Results show that retarded injections show less cycle-to-cycle variation due to temperature variations. Advanced in-bowl injections show a stochastic behavior in the location of the first combustion, due to large variations in local fuel rich zones. For the double injection case the main injection cools the bulk temperature and hence delays the start of combustion before igniting in the fuel rich zones.
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| 10. |
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| 11. |
- Maurin Söderholm, Hanna, et al.
(författare)
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Research challenges in prehospital care : the need for a simulation-based prehospital research laboratory
- 2019
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Ingår i: Advances in Simulation. - : BioMed Central. - 2059-0628 .- 2059-0628. ; 4:3, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for improved research in the field of prehospital care. At the same time, there are many barriers in prehospital research due to the complex context, posing unique challenges for research, development, and evaluation. The present paper argues for the potential of simulation for prehospital research, e.g., through the development of an advanced simulation-based prehospital research laboratory. However, the prehospital context is different from other healthcare areas, which implies special requirements for the design of this type of laboratory, in terms of simulation width (including the entire prehospital work process) and depth (level of scenario detail). A set of features pertaining to simulation width, scenario depth, equipment, and personnel and competence are proposed. Close tailoring between these features and the prehospital research problems and context presents great potential to improve and further prehospital research.
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| 12. |
- Muric, Kenan, et al.
(författare)
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The Potential of SNCR Based NOx Reduction in a Double Compression Expansion Engine
- 2018
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2018-April
-
Tidskriftsartikel (refereegranskat)abstract
- Selective Non-Catalytic Reduction (SNCR), used to reduce the emissions of nitrogen oxides (NOx), has been a well-established technology in the power plant industry for several decades. The SNCR technique is an aftertreatment strategy based on thermal reduction of NOx at high temperatures. In the compression ignition engine application, the technology has not been applicable due to low exhaust temperatures, which makes the SCR (Selective Catalytic Reduction) system essential for efficient nitrogen oxide reduction to fulfill the environment legislation. For a general Double Compression Expansion Engine (DCEE) the complete expansion cycle is split in two separate cycles, i.e. the engine is a split cycle engine. In the first cylinder the combustion occurs and in the second stage the combustion gas is introduced and further expanded in a low-pressure expansion cylinder. The combustion cylinder is connected with the expansion cylinder through a large insulated high-pressure tank. If an ammonia based solution is injected after the combustion cylinder, the residence time and high gas temperature in the high-pressure tank allows the Selective Non-Catalytic Reduction mechanisms to ensue. In this paper, AUS 32 vaporization efficiency was studied by injection droplet distribution measurements and CFD simulations. The Selective Non-Catalytic Reduction concept was evaluated utilizing a 1D GT-SUITE model of a potential DCEE concept where the SNCR based mechanisms were added. Engine speed, normalized stoichiometric ratio (NSR), load and air-fuel excess ratio were swept in the 1D simulation process. The simulation results suggest efficient vaporization of AUS 32 and the presence of SNCR mechanisms in the Double Compression Expansion Engine's medium and high load operating points was verified with conversion efficiency above 50 % in some of the simulation cases for NSR = 1 and close to 80-100 % for NSR = 2 and NSR = 3 when the exhaust gas temperature from the combustion cylinder was in the optimal range for SNCR based reactions.
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| 13. |
- Muric, Kenan, et al.
(författare)
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Thermal Reduction of NOx in a Double Compression Expansion Engine by Injection of AAS 25 and AUS 32 in the Exhaust Gases
- 2019
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Ingår i: International Powertrains, Fuels & Lubricants Meeting. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019
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Konferensbidrag (refereegranskat)abstract
- The double compression expansion engine (DCEE) is a promising concept for high engine efficiency while fulfilling the most stringent European and US emission legislation. The complete thermodynamic cycle of the engine is split among several cylinders. Combustion of fuel occurs in the combustion cylinder and in the expansion cylinder the exhaust gases are over expanded to obtain high efficiency. A high-pressure tank is installed between these two cylinders for after-treatment purposes. One proposal is to utilize thermal reduction of nitrogen oxides (NOx) in the high-pressure tank as exhaust temperatures can be sufficiently high (above 700 °C) for the selective non-catalytic reduction (SNCR) reactions to occur. The exhaust gas residence time at these elevated exhaust temperatures is also long enough for the chemical reactions, as the volume of the high-pressure tank is substantially larger than the volume of the combustion cylinders. In this paper a single-cylinder D13 engine was run together with a 30 l high-pressure tank, with and without a diesel oxidation catalyst (DOC). AUS 32 and an ammonia-water solution (AAS 25) are injected before the high-pressure tank at different exhaust temperatures to study the thermal reduction of NOx produced from the combustion and the impact of the DOC. Additionally, the normalized stoichiometric ratio (NSR) was swept to evaluate the maximum NOx reduction potential of SNCR. Experimental results showed that very high NOx conversion efficiencies could be achieved for both AUS 32 and AAS 25. NOx conversion efficiencies of 80 % were obtained for NSR = 3. At stoichiometric NOx reductant dosing (NSR = 1), 40 % of nitrogen oxides could be reduced thermally. Presence of a DOC would decrease the efficiency of the thermal reduction as it oxidizes ammonia. At exhaust gas temperatures below 400°C, platinum in the DOC reduced NOx with a maximum conversion efficiency of 31 % at 350°C.
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| 14. |
- Otamiri, JC, et al.
(författare)
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Ammoxidation of Toluene by YBa2Cu3O6 + x and Copper Oxides. Activity and XPS Studies
- 1990
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Ingår i: Applied Catalysis. - 0166-9834. ; 65:1, s. 159-174
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic activities of YBa2Cu3O6+x and copper oxides have been studied in the ammoxidation of toluene. At low oxygen pressures, over YBa2Cu3O6+x selective ammoxidation to benzonitrile occurs, whereas at high pressures, only total combustion of toluene to carbon oxides is observed. X-ray photoelectron spectroscopy (XPS) analysis of YBa2Cu3O6+x catalysts indicates predominance of Cu(I) states under partial ammoxidation conditions, while under total oxidation conditions, Cu(II) states are predominant. Comparison with the catalytic performance of copper oxide catalysts shows that differences do exist. The catalysis by YBa2Cu3O6+x is greatly influenced by the oxygen content of the bulk material despite its surface composition.
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| 15. |
- Otamiri, JC, et al.
(författare)
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Effect of Zn Substitutions in YBa2Cu3O6 + x Phases on Reactivity during the Ammoxidation of Toluene
- 1991
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Ingår i: Journal of the Chemical Society, Faraday Transactions. - : Royal Society of Chemistry (RSC). - 0956-5000 .- 1364-5455. ; 87:8, s. 1265-1271
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Tidskriftsartikel (refereegranskat)abstract
- Zn substitution in Y-Ba-Cu-O phases influences the catalytic ammoxidation of toluene. The activity for formation of both benzonitrile and CO2 at low and high O2 pressures, respectively, decreases strongly with increasing Zn content up to 4%. Above this substitution level, the activity, however, increases slightly. Characterisations of the surface by XPS and of the bulk by XRD analysis, indicate the presence of overlayers on the catalysts. In these overlayers, irrespective of the Zn content of catalysts, Cu1 states predominate at low O2 pressure and Cu11 at high pressure. These states are associated with selective and non-selective properties, respectively. The activity of the catalysts shows a general tendency to increase with surface copper concentrations as found from XPS studies. However, strong deviations from linearity indicate that the activity of the overlayer is greatly influenced by the bulk acting as a support.
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| 16. |
- Tanner, Lloyd, et al.
(författare)
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Citrullination of extracellular histone H3.1 reduces antibacterial activity and exacerbates its proteolytic degradation
- 2021
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Ingår i: Journal of Cystic Fibrosis. - : Elsevier BV. - 1873-5010 .- 1569-1993. ; 20:2, s. 346-355
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cystic fibrosis (CF), involves excessive airway accumulation of neutrophils, often in parallel with severe infection caused by Pseudomonas aeruginosa. Free histones are known to possess bactericidal properties, but the degree of antibacterial activity exerted on specific lung-based pathogens is largely unknown. Neutrophils have a high content of peptidyl deiminase 4 (PADI4), which citrullinate cationic peptidyl-arginines. In histone H3.1, several positions in the NH2-terminal tail are subject to citrullination.METHODS: Full-length and segmented histone subunit H3.1 was investigated for bactericidal activity towards P. aeruginosa (strain PAO1). PADI4-induced citrullination of histone H3.1 was assessed for antibacterial activity towards P. aeruginosa. Next, the effect of neutrophil elastase (NE)-mediated proteolysis of histone H3.1 was investigated. Finally, PADI4, H3.1, and citrullinated H3.1 were examined in healthy control and CF patient lung tissues.RESULTS: Full-length histone H3.1 and sections of the histone H3.1 tail, displayed bactericidal activity towards P. aeruginosa. These antibacterial effects were reduced following citrullination by PADI4 or proteolysis by NE. Interestingly, citrullination of histone H3.1 exacerbated NE-mediated degradation. In CF lung tissue, citrullinated histone H3.1 and PADI4 immunoreactivity was abundant. Degraded histone H3.1 was detected in the sputum of CF patients but was absent in the sputum of healthy controls.CONCLUSIONS: Citrullination impairs the antibacterial activity of histone H3.1 and exacerbates its proteolytic degradation by NE. Citrullination is likely to play an important role during resolution of acute inflammation. However, in chronic inflammation akin to CF, citrullination may dampen host defense and promote pathogen survival, as exemplified by P. aeruginosa.
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| 17. |
- Vass, Mate, et al.
(författare)
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Microeukaryote community coalescence strengthens community stability and elevates diversity
- 2024
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press. - 0168-6496 .- 1574-6941. ; 100:8
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Tidskriftsartikel (refereegranskat)abstract
- Mixing of entire microbial communities represents a frequent, yet understudied phenomenon. Here, we mimicked estuarine condition in a microcosm experiment by mixing a freshwater river community with a brackish sea community and assessed the effects of both environmental and community coalescences induced by varying mixing processes on microeukaryotic communities. Signs of shifted community composition of coalesced communities towards the sea parent community suggest asymmetrical community coalescence outcome, which, in addition, was generally less impacted by environmental coalescence. Community stability, inferred from community cohesion, differed among river and sea parent communities, and increased following coalescence treatments. Generally, community coalescence increased alpha diversity and promoted competition from the introduction (or emergence) of additional (or rare) species. These competitive interactions in turn had community stabilizing effect as evidenced by the increased proportion of negative cohesion. The fate of microeukaryotes was influenced by mixing ratios and frequencies (i.e. one-time versus repeated coalescence). Namely, diatoms were negatively impacted by coalescence, while fungi, ciliates, and cercozoans were promoted to varying extents, depending on the mixing ratios of the parent communities. Our study suggests that the predictability of coalescence outcomes was greater when the sea parent community dominated the final community, and this predictability was further enhanced when communities collided repeatedly.
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| 18. |
- Wang, Zhenkan, et al.
(författare)
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Simultaneous 36 kHz PLIF/chemiluminescence imaging of fuel, CH2O and combustion in a PPC engine
- 2019
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 37:4, s. 4751-4758
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Tidskriftsartikel (refereegranskat)abstract
- The requirements on high efficiency and low emissions of internal combustion engines (ICEs) raise the research focus on advanced combustion concepts, e.g., premixed-charge compression ignition (PCCI), partially premixed compression ignition (PPCI), reactivity controlled compression ignition (RCCI), partially premixed combustion (PPC), gasoline compression ignition (GCI) etc. In the present study, an optically accessible engine is operated in PPC mode, featuring compression ignition of a diluted, stratified charge of gasoline-like fuel injected directly into the cylinder. A high-speed, high-power burst-mode laser system in combination with a high-speed CMOS camera is employed for diagnostics of the autoignition process which is critical for the combustion phasing and efficiency of the engine. To the authors' best knowledge, this work demonstrates for the first time the application of the burst-system for simultaneous fuel tracer planar laser induced fluorescence (PLIF) and chemiluminescence imaging in an optical engine, at 36 kHz repetition rate. In addition, high-speed formaldehyde PLIF and chemiluminescence imaging are employed for investigation of autoignition events with a high temporal resolution (5 frames/CAD). The development of autoignition together with fuel or CH2O distribution are simultaneously visualized using a large number of consecutive images. Prior to the onset of combustion the majority of both fuel and CH2O are located in the recirculation zone, where the first autoignition also occurs. The ability to record, in excess of 100 PLIF images, in a single cycle brings unique possibilities to follow the in-cylinder processes without the averaging effects caused by cycle-to-cycle variations.
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| 19. |
- Wang, Zhenkan, et al.
(författare)
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Ultra-High Speed Fuel Tracer PLIF Imaging in a Heavy-Duty Optical PPC Engine
- 2018
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2018-April
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Tidskriftsartikel (refereegranskat)abstract
- In order to meet the requirements in the stringent emission regulations, more and more research work has been focused on homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC) or partially premixed compression ignition (PCCI) as they have the potential to produce low NOx and soot emissions without adverse effects on engine efficiency. The mixture formation and charge stratification influence the combustion behavior and emissions for PPC/PCCI, significantly. An ultra-high speed burst-mode laser is used to capture the mixture formation process from the start of injection until several CADs after the start of combustion in a single cycle. To the authors' best knowledge, this is the first time that such a high temporal resolution, i.e. 0.2 CAD, PLIF could be accomplished for imaging of the in-cylinder mixing process. The capability of resolving single cycles allows for the influence of cycle-to-cycle variations to be eliminated. This ability to study individual cycles aids the understanding of the mixture formation process as well as the cycle-to-cycle variations. Strong air entrainment at the boundary layer can be clearly observed and followed as the mixing process progresses. The formation of eddies created by the shear force and their rotational motion can be continuously observed during the mixing process. The interaction between two adjacent spray plumes in the recirculation zone is well captured and studied. In addition, the mixing process resulting in the stratified fuel charge being located in the recirculation zone before the SOC while the areas along the original spray axis are leaned out after the end of injection, can be followed in one time sequence. Moreover, the auto-ignition position and early flame development can be studied, from the high-speed chemiluminescence imaging, together with the fuel distribution in the combustion chamber.
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| 20. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 21. |
- Ahlin, Sofie, 1985, et al.
(författare)
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Fracture risk after three bariatric surgery procedures in Swedish obese subjects : up to 26 years follow-up of a controlled intervention study
- 2020
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 287:5, s. 546-557
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previous studies have reported an increased fracture risk after bariatric surgery. Objective: To investigate the association between different bariatric surgery procedures and fracture risk. Methods: Incidence rates and hazard ratios for fracture events were analysed in the Swedish Obese Subjects study; an ongoing, nonrandomized, prospective, controlled intervention study. Hazard ratios were adjusted for risk factors for osteoporosis and year of inclusion. Information on fracture events were captured from the Swedish National Patient Register. The current analysis includes 2007 patients treated with bariatric surgery (13.3% gastric bypass, 18.7% gastric banding, and 68.0% vertical banded gastroplasty) and 2040 control patients with obesity matched on group level based on 18 variables. Median follow-up was between 15.1 and 17.9 years for the different treatment groups. Results: During follow-up, the highest incidence rate for first-time fracture was observed in the gastric bypass group (22.9 per 1000 person-years). The corresponding incidence rates were 10.4, 10.7 and 9.3 per 1000 person-years for the vertical banded gastroplasty, gastric banding and control groups, respectively. The risk of fracture was increased in the gastric bypass group compared with the control group (adjusted hazard ratio [adjHR] 2.58; 95% confidence interval [CI] 2.02–3.31; P < 0.001), the gastric banding group (adjHR 1.99; 95%CI 1.41–2.82; P < 0.001), and the vertical banded gastroplasty group (adjHR 2.15; 95% CI 1.66–2.79; P < 0.001). Conclusions: The risk of fracture is increased after gastric bypass surgery. Our findings highlight the need for long-term follow-up of bone health for patients undergoing this treatment.
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| 22. |
- Ahlin, Sofie, 1985, et al.
(författare)
-
Macrophage Gene Expression in Adipose Tissue is Associated with Insulin Sensitivity and Serum Lipid Levels Independent of Obesity.
- 2013
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Ingår i: Obesity (Silver Spring, Md.). - : Wiley. - 1930-739X .- 1930-7381. ; 21:12
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Obesity is linked to both increased metabolic disturbances and increased adipose tissue macrophage infiltration. However, whether macrophage infiltration directly influences human metabolism is unclear. The aim of this study was to investigate if there are obesity-independent links between adipose tissue macrophages and metabolic disturbances. Design and Methods: Expression of macrophage markers in adipose tissue was analyzed by DNA microarrays in the SOS Sib Pair study and in patients with type 2 diabetes and a BMI-matched healthy control group. Results: The expression of macrophage markers in adipose tissue was increased in obesity and associated with several metabolic and anthropometric measurements. After adjustment for BMI, the expression remained associated with insulin sensitivity, serum levels of insulin, C-peptide, high density lipoprotein cholesterol (HDL-cholesterol) and triglycerides. In addition, the expression of most macrophage markers was significantly increased in patients with type 2 diabetes compared to the control group. Conclusion: Our study shows that infiltration of macrophages in human adipose tissue, estimated by the expression of macrophage markers, is increased in subjects with obesity and diabetes and associated with insulin sensitivity and serum lipid levels independent of BMI. This indicates that adipose tissue macrophages may contribute to the development of insulin resistance and dyslipidemia.
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| 23. |
- Al-Olama, Mohamed, et al.
(författare)
-
The peptide AF-16 decreases high interstitial fluid pressure in solid tumors.
- 2011
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Ingår i: Acta oncologica (Stockholm, Sweden). - 1651-226X.
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Background. The high interstitial fluid pressure (IFP) in solid tumors restricts the access to nutrients, oxygen and drugs. Material and methods. We investigated the ability of the peptide AF-16, involved in water and ion transfer through cell membranes, to lower the IFP in two different solid rat mammary tumors, one chemically induced, slowly growing, and the other transplantable, and rapidly progressing having high cellularity. AF-16 was administered either in the tumor capsule, intranasally or intravenously. The IFP was measured by a miniature fiber optic device. Results. AF-16 significantly lowered the IFP in both the slowly and the rapidly progressing tumors, whether administrated locally or systemically. The AF-16 induced IFP reduction was maximal after 90 min, lasted at least 3 h, and returned to pretreatment levels in less than 24 h. Topical AF-16 transiently reduced the IFP in the DMBA tumors from 17.7 ± 4.2 mmHg to 8.6 ± 2.1 mmHg. Conclusion. We conclude that AF-16 transiently and reversibly lowered the high IFP in solid tumors during a few hours, which might translate into improved therapeutic efficacy.
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| 24. |
- Anderbrant, Olle, et al.
(författare)
-
Electrophysiological responses of carrot psyllids (Trioza apicalis), in different phases of their life cycle, to volatile carrot and conifer compounds
- 2020
-
Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 144:3, s. 236-240
-
Tidskriftsartikel (refereegranskat)abstract
- Carrot psyllids (Trioza apicalis) pose a constant threat to carrot production in parts of Europe, and treatments with chemical insecticides are common. To be able to develop alternative control tactics, more knowledge about the psyllid's host-finding behaviour and underlying physiology is needed. Using single-sensillum recordings from overwintered and non-overwintered males and females, we found essentially identical responses for the two groups and for both sexes. Using six compounds emanating from carrots or conifers, the psyllids' overwintering plants, and extracts of carrot leaves, five different olfactory sensory neuron classes could be distinguished from our high-quality recordings, viz. #1 responding strongly and exclusively to terpinene-4-ol, #2 responding strongly and most often exclusively to nonanal, #3 responding moderately strongly to terpinolene, #4 responding strongly to (Z)-3-hexenal and most often weaker to terpinolene, #5 responding exclusively to carrot extract.
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| 25. |
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| 26. |
- Andersson, Arne, et al.
(författare)
-
A New Analysis of Combinatorial vs Simultaneous Auctions: Revenue and Efficiency
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We address the fundamental issue of revenue and efficiency in the combinatorial and simultaneous auction using a novel approach. Specifically, upper and lower bounds are constructed for the first-price sealed-bid setting of these two auctions. The question of revenue is important yet very few results can be found in the literature. Only for very small instances with 2 items have comparisons been made. Krishna et. al. find that allowing combinatorial bids result in lower revenue compared to a second price simultaneous auction. We formulate a lower bound on the first-price combinatorial auction and an upper bound on the first-price simultaneous auction for larger problems with several items and many bidders, in a model where bidders have synergies from winning a specific set of items. We show that the combinatorial auction is revenue superior to the simultaneous auction for a specific instance in pure symmetric equilibrium and give two generalized upper bounds on revenue for the simultaneous auction.
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| 27. |
- Andersson, Arne, et al.
(författare)
-
A New Analysis of Revenue in the Combinatorial and Simultaneous Auction
- 2009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We prove that in many cases, a first-price sealed-bid combinatorial auction gives higher expected revenue than a sealed-bid simultaneous auction. This is the first theoretical evidence that combinatorial auctions indeed generate higher revenue, which has been a common belief for decades.We use a model with many bidders and items, where bidders are of two types: (i) single-bidders interested in only one item and (ii) synergy-bidders, each interested in one random combination of items. We provide an upper bound on the expected revenue for simultaneous auctions and a lower bound on combinatorial auctions. Our bounds are parameterized on the number of bidders and items, combination size, and synergy.We derive an asymptotic result, proving that as the number of bidders approach infinity, expected revenue of the combinatorial auction will be higher than that of the simultaneous auction. We also provide concrete examples where the combinatorial auction is revenue-superior.
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| 28. |
- Andersson, Arne, et al.
(författare)
-
A study of the ageing and deactivation phenomena occurring during operation of an iron molybdate catalyst in formaldehyde production
- 2006
-
Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 112:1-4, s. 40-44
-
Tidskriftsartikel (refereegranskat)abstract
- Catalyst from a Perstorp Formox formaldehyde plant, operating with high inlet concentration of methanol (10.2 vol.%), was discharged from single tubes of a multi-tube reactor after half the expected lifetime of the catalyst and again after termination of the load. Each tube was filled with two different layers of catalyst. From the inlet of the reactor the first layer was a catalyst mixed with inert rings, which was followed by a second layer of pure catalyst extending from the middle to the outlet of the reactor. Catalyst fractions from the two layers were characterized with various techniques including BET, Fourier transform Raman (FT-Raman) spectroscopy, X-ray diffraction (XRD), elemental analysis with atomic absorption spectroscopy (AAS) and activity measurements. It was found that the surface area of the catalyst in the mixed layer increases during operation while a small decrease is noticeable for the catalyst below in the pure layer. Elemental analysis, XRD and FT-Raman show that during operation of the catalyst there is migration of Mo species from the upper part of the reactor towards the outlet. Activity measurements reveal severe deactivation of the catalyst in the mixed layer. It is concluded that the deactivation primarily is due to formation of volatile species formed by the MoO3 surface reacting methanol, causing a decrease of the MoO3/Fe-2(MoO4)(3) mole ratio in the catalyst. Concerning the catalyst in the pure layer, the condensation of needle-like crystals of MoO3 mainly occurs on the external surface of the catalyst ring.
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| 29. |
- Andersson, Arne, et al.
(författare)
-
A substantial increase of the impact factor
- 2012
-
Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 117:4, s. 353-354
-
Tidskriftsartikel (refereegranskat)
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| 30. |
- Andersson, Arne, et al.
(författare)
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Activities of V-Ti-O Catalysts in the Ammoxidation of 3-Picoline
- 1980
-
Ingår i: Journal of Catalysis. - : Elsevier BV. - 1090-2694 .- 0021-9517. ; 65:1, s. 9-15
-
Tidskriftsartikel (refereegranskat)abstract
- Ammoxidation of 3-picoline was studied on reduced V-Ti-O catalysts with V6O13 as the major vanadium oxide. The results showed that the initial activity as a function of the TiO2 content reached a maximum at 50–60 mole% TiO2. It is proposed that there is maximum contact between the vanadium and titanium phases at this composition, which results in a weakening of the (VO)3+ surface bond. The selectivity of formation of nicotinonitrile exhibited a maximum of 83% at 10 mole% TiO2 and minima of 73 and 75% at 0 and 30 mole% TiO2, respectively. At higher TiO2 concentrations the selectivity increased continuously to 83% at 90 mole% TiO2. The variation of the selectivity of formation of nicotinonitrile depends on the View the MathML source ratio in the TiO2 phase. It was also found that the conversion and yields varied with the reaction time, which could be explained by the fact that reduced vanadium oxides were oxidized to V2O5 during the ammoxidation process. This oxidation leads to the formation of active and highly selective boundary surfaces between the TiO2-promoted vanadium oxides V6O13 and V2O5.
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| 31. |
- Andersson, Arne
(författare)
-
Activities of V-Ti-O Catalysts in the Ammoxidation of 3-Picoline. II. Acid-Base Properties and Infrared Spectra
- 1982
-
Ingår i: Journal of Catalysis. - : Elsevier BV. - 1090-2694 .- 0021-9517. ; 76:1, s. 144-156
-
Tidskriftsartikel (refereegranskat)abstract
- The acidity and basicity of prereduced V-Ti-O catalysts were measured by adsorption of NH3 and CO2. It was found that a high activity in the ammoxidation of 3-picoline corresponds to a relatively small amount of acidic sites. A catalyst selective in the formation of nicotinonitrile requires high concentrations of both acidic and basic sites. These results are discussed, and can be correlated if the acidity is considered to be a measure of the hydroxyl group concentration, and the basicity a measure of oxygen vacancies in the vicinity of VO groups. Also, the infrared spectra of the prereduced catalysts were recorded. A new band was found at 995 cm−1. The same band appeared in a homogeneous mixture of V2O5 and V6O13. It is proposed that this band can be assigned to VO bonds in a reduced V2O5phase with a number of disordered vacancies in the lattice, or a nonstoichiometric V6O13 phase. The shift in frequency relative to that of (VO)3+ shows that these bonds are weaker, and probably also more active. The effect of TiO2 is to increase the amount of V4+ in the vanadium oxide lattice. This is caused by dissolution of Ti4+ in the V2O5 melt during the catalyst preparation.
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| 32. |
- Andersson, Arne, et al.
(författare)
-
Activities of Vanadium Oxides in Ammoxidation of 3-Picoline
- 1979
-
Ingår i: Journal of Catalysis. - 1090-2694. ; 58:3, s. 383-395
-
Tidskriftsartikel (refereegranskat)abstract
- Ammoxidation of 3-picoline to nicotinonitrile was studied on V2O5, V6O13, and V2O4 catalysts in a fixed-bed integral reactor. The activity studies showed that V6O13 was the most active and selective catalyst of the pure oxides, with a maximum yield of 76% nicotinonitrile at 365 °C. The maximum yield on V2O5 catalyst was 34%, and was obtained at a higher temperature, 458 °C. V2O4 was found to be inactive under the conditions studied. The activities and selectivities of the oxides changed rapidly with reaction time when V6O13 and V2O4 were studied. By means of X-ray diffraction and a titrimetric method, the average oxidation number of vanadium was determined, V6O13 was both oxidized and reduced during the reaction; V2O4 was oxidized, while a relatively smaller reduction of V2O5 could be detected. The experiments showed that the V6O13 catalyst used, with both V2O5 and V6O13 phases present, was more selective than any of the pure oxides. This may be explained by active boundary surfaces. Also a mechanism of formation of nicotinonitrile is proposed, which includes a step in which an adsorbed aldehyde complex reacts with ammonia.
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| 33. |
- Andersson, Arne, et al.
(författare)
-
Ammoxidation of 3-Picoline: An Activity and High-Resolution Electron Microscopic Investigation of Vanadium Oxide Catalysts
- 1986
-
Ingår i: Journal of Catalysis. - 1090-2694. ; 98:1, s. 204-220
-
Tidskriftsartikel (refereegranskat)abstract
- A V2O5 catalyst was used in the ammoxidation of 3-picoline to nicotinonitrile. It was observed that the selectivity for the formation of CO2 as a function of temperature passed through a minimum. This is explained to be due to the existence of weakly bonded electrophilic oxygen species at low temperatures, and an increasing degradation involving O2− at high temperatures. A comparison of two different V2O5 preparations shows the beneficial effect of the V2O5(010) plane on the formation of nicotinonitrile. The exposure of planes other than the (010) plane as the source of formation of CO2 is discussed by consideration of bond strength values. The activity, selectivity, and composition of the charged V2O5 catalyst were followed as a function of time-on-stream at various temperatures. It was found that the V2O5 phase was reduced in the course of the reaction. V4O9, VO2(B), VO2 (tetragonal), and even more reduced phases were formed depending upon the reaction temperature used. Of the pure oxides, V4O9 was found to be both less active and less selective than V2O5. VO2(B), however, is more active but less selective compared to V2O5. The phases formed were characterized by various methods including high-resolution transmission electron microscopy (HRTEM). This technique made it possible to image the View the MathML source phase boundary for the first time. The general direction of this boundary is parallel to the (301) plane of V2O5. Micrographs of VO2(B) show that the nature of defects formed depends on the reaction temperature. After use at 695 K two types of planar twin lamellae were formed. At a slightly higher temperature partly amorphous defects appeared. The influence on the catalytic reaction of the phase boundaries and defects formed is discussed.
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| 34. |
- Andersson, Arne, et al.
(författare)
-
Ammoxidation of toluene over molybdenum oxides
- 1988
-
Ingår i: Catalysis Letters. - 1011-372X. ; 1:11, s. 377-383
-
Tidskriftsartikel (refereegranskat)abstract
- The ammoxidation of toluene was studied both in presence and absence of gaseous oxygen over MoO3 and in situ prepared Mo4O11 (orth.) and MoO2. Irrespective of the partial pressure of oxygen, total reaction rates decrease in the following order: MoO3 > Mo4O11 > MoO2. The corresponding sequence for the selectivity towards formation of benzonitrile was found to depend on the partial pressure of oxygen. In two phase samples, no synergistic effects were observed for the formations of nitrile and carbon oxides. A comparison of rates for selective and nonselective products obtained in presence of gaseous oxygen with those obtained in its absence yield information as to whether the various products are formed at identical or different crystal faces. In the case of MoO3, nitrile and carbon oxides were found to be competitively formed at the same faces, while over MoO2 they are formed at different faces. Both options seem to prevail on
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| 35. |
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| 36. |
- Andersson, Arne, et al.
(författare)
-
Amyloid Deposition in Transplanted Human Pancreatic Islets : A Conceivable Cause of Their Long-Term Failure
- 2008
-
Ingår i: EXPERIMENTAL DIABETES RESEARCH. - : Hindawi Limited. - 1687-5214 .- 1687-5303. ; 2008:562985
-
Tidskriftsartikel (refereegranskat)abstract
- Following the encouraging report of the Edmonton group, there was a rejuvenation of the islet transplantation field. After that, more pessimistic views spread when long-term results of the clinical outcome were published. A progressive loss of the beta-cell function meant that almost all patients were back on insulin therapy after 5 years. More than 10 years ago, we demonstrated that amyloid deposits rapidly formed in human islets and in mouse islets transgenic for human IAPP when grafted into nude mice. It is, therefore, conceivable to consider amyloid formation as one potential candidate for the long-term failure. The present paper reviews attempts in our laboratories to elucidate the dynamics of and mechanisms behind the formation of amyloid in transplanted islets with special emphasis on the impact of long-term hyperglycemia.
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| 37. |
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| 38. |
- Andersson, Arne
(författare)
-
An Oxidized Surface State Model of Vanadium Oxides and Its Application to Catalysis
- 1982
-
Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596. ; 42:3, s. 263-275
-
Tidskriftsartikel (refereegranskat)abstract
- The charge distribution around the VO bonds in V2O5, V6O13, and V2O4 was calculated by using an empirical formula. The same expression was also used to calculate the oxygen bond strengths on the surface. The surfaces of lower oxides were treated as though they were in an oxidized state which is believed to correspond to the conditions in oxidation and ammoxidation processes. The result is that O2−, in the form of VO surface groups, is responsible for the catalytic oxidation of hydrocarbons. O− is hindered by the formation of stable OH− groups. The positions of lower valent oxygens are considered to be vacant because of a slow reoxidation rate. In V2O5 the VO groups are located on the (010) plane, while in V6O13 they are mainly located on the (001) surface plane. But in this case the (100) and (010) surface planes also have some VO groups. The catalytic activity of the rutile form of V2O4 is limited by sterical factors, but the (110) surface plane has oxygens pointing perpendicular out of the surface.
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| 39. |
- Andersson, Arne, et al.
(författare)
-
Approximate Indexed Lists.
- 1998
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Ingår i: Journal of Algorithms. ; 29:2
-
Tidskriftsartikel (refereegranskat)abstract
- Let the position of a list element in a list be the number of elements preceding it plus one. An indexed list supports the following operations on a list: Insert; delete; return the position of an element; and return the element at a certain position. The order in which the elements appear in the list is completely determined by where the insertions take place; we do not require the presence of any keys that induce the ordering.We consider approximate indexed lists, and show that a tiny relaxation in precision of the query operations allows a considerable improvement in time complexity. The new data structure has applications in two other problems; namely, list labeling and subset rank.
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| 40. |
- Andersson, Anneli, 1992-, et al.
(författare)
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Attention-deficit/hyperactivity disorder and smoking habits in pregnant women
- 2020
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 15:6
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Attention-deficit/hyperactivity disorder (ADHD) has been associated with an increased risk of tobacco smoking, and more difficulties with smoking cessation compared to non-ADHD individuals. Women with ADHD may therefore show elevated rates of smoking during pregnancy.Aims: To examine the association between ADHD and smoking habits among pregnant women in Sweden and Norway.Methods: Women pregnant for the first time were identified in Sweden (n = 622,037), and Norway (n = 293,383), of which 1.2% (n = 7,444), and 1.7% (n = 4,951) were defined as having ADHD, respectively. Data on smoking habits were collected early and late in pregnancy.Results: In Sweden, ADHD was associated with an increased risk of smoking early in pregnancy, adjusted risk ratio (adjRR) 2.69 (95% confidence interval, 2.58-2.81), and late in pregnancy, adjRR 2.95 (2.80-3.10). Similar findings were observed in the Norwegian data, early in pregnancy, adjRR 2.31 (2.21-2.40), and late in pregnancy, adjRR 2.56 (2.42-2.70). Women with ADHD were more likely to continue smoking during pregnancy, compared to women without ADHD, both in Sweden adjRR 1.13 (1.10-1.17), and in Norway, adjRR 1.16 (1.12-1.20). Having a sibling diagnosed with ADHD was associated with an increased risk of smoking early and late in pregnancy, in both Sweden and Norway.Conclusions: Women with ADHD are considerably more likely to smoke early and late in (their first) pregnancy and are less likely to stop smoking between the two time points. Smoking, early and late in pregnancy, co-aggregates in families with ADHD. Smoking prevention and intervention programs should be targeted towards women with ADHD, specifically during their childbearing years, to ensure better mother and child outcomes.
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| 41. |
- Andersson, Arne
(författare)
-
Balanced Binary Search Trees
- 2005
-
Ingår i: Handbook of Data Structures and Applications. - : CRC Press. - 1584884355 ; , s. 1392-
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 42. |
- Andersson, Arne, et al.
(författare)
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Catalytic Anisotropy of MoO3 in the Oxidative Ammonolysis of Toluene
- 1988
-
Ingår i: Journal of Catalysis. - : Elsevier BV. - 1090-2694 .- 0021-9517. ; 114:2, s. 332-346
-
Tidskriftsartikel (refereegranskat)abstract
- The oxidative ammonolysis of toluene, i.e., ammoxidation without the presence of molecular oxygen, was studied over a series of samples of MoO3 crystals. The specific surface areas of the various faces were determined from SEM micrographs. Correlations between activities and surface planes were found. For the formation of nitrile the specific activity decreased in the order {001} and {h01} > {100} > {010}. Also, for the formation of carbon oxides the terminations in the [001] direction were found to be especially active. These results are discussed in relation to surface structures and bond strength values of various oxygen species. It is concluded that the presence of both oxygen vacancies and nucleophilic oxygen species is a prerequisite for selective reaction to occur and that electrophilic oxygen species are the source for formation of carbon oxides. The characteristics of the various faces, as they emerge from the results on oxidative ammonolysis of toluene, seem to be of general significance for reactions occurring at the same types of active sites. They are shown to be applicable to results published in the literature on the oxidation of both propene and isobutene.
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| 43. |
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| 44. |
- Andersson, Arne, et al.
(författare)
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Comment on "self-indexed sort"
- 1996
-
Ingår i: SIGPLAN notices. - : Association for Computing Machinery (ACM). - 0362-1340 .- 1558-1160. ; 31:8, s. 40-41
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 45. |
- Andersson, Arne, et al.
(författare)
-
Dynamic Ordered Sets with Exponential Search Trees
- 2007
-
Ingår i: Journal of the ACM. - : Association for Computing Machinery (ACM). - 0004-5411 .- 1557-735X. ; 54:3, s. 1236460-
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce exponential search trees as a novel technique for converting static polynomial space search structures for ordered sets into fully-dynamic linear space data structures. This leads to an optimal bound of O(log n/log log n) for searching and updating a dynamic set X of n integer keys in linear space. Searching X for an integer y means finding the maximum key in X which is smaller than or equal to y. This problem is equivalent to the standard text book problem of maintaining an ordered set. The best previous deterministic linear space bound was O(log n/log log n) due to Fredman and Willard from STOC 1990. No better deterministic search bound was known using polynomial space. We also get the following worst-case linear space trade-offs between the number n, the word length W, and the maximal key U < 2W: O(min log log n + log n/logW, log log n log log U/log log log U). These trade-offs are, however, not likely to be optimal. Our results are generalized to finger searching and string searching, providing optimal results for both in terms of n.
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| 46. |
- Andersson, Arne, et al.
(författare)
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Dynamic String Searching
- 2001
-
Ingår i: ACM-SIAM symposium on Discrete algorithms, SODA.
-
Konferensbidrag (refereegranskat)
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| 47. |
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| 48. |
- Andersson, Arne, et al.
(författare)
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Efficient resource allocation with non-concave objective functions
- 2001
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Ingår i: Computational Optimization and Applications. - 0926-6003. ; 20:3, s. 281-298
-
Tidskriftsartikel (refereegranskat)abstract
- We consider resource allocation with separable objective functions defined over subranges of the integers. While it is well known that (the maximization version of) this problem can be solved efficiently if the objective functions are concave, the general
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| 49. |
- Andersson, Arne, 1956
(författare)
-
Engine Thermal Management in Heavy Duty Vehicles
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Future regulations on noise and exhaust emissions have a large impact on heavy duty engine installations. Cooled EGR is used for NOx abatement. Better sealed engine encapsulations are used to meet new noise regulations. Engine thermal management is therefore becoming an increasingly important discipline.In order to meet those challenges, improvements are needed in several areas. Steady state performance is always important for trucks due to low power to gross cargo weight ratio. Two major steady state situations are climbing of a very long hill with full load in extreme heat and cruising at constant road speed on a flat road with average load at average temperature. In the first case cooling performance requirements has to be met. In the second case parasitic losses has to be minimised.The cooling system can be reduced to three sub systems: The hot side (coolant pump), the heat exchanger (radiator) and the cold side (cooling air fan). The key components for steady state performance are the cooling fan and the radiator. The key to good fan performance is the optimisation between fan and installation. The limiting factor for radiator development on the other hand is fouling resistance.The requirement for coolant flow is very fluctuating. Usually only a small fraction of the available flow is routed through the radiator by the thermostat. Coolant pump speed control would reduce parasitic losses significantly. An innovative compromise, a way of controlling the pump performance with the thermostat is presented. Electronic control systems make advanced control strategies possible. A comprehensive model for transient engine thermal management simulation has been developed in order to fully utilise this potential. The aim was to implement a model where several aspects like heat flow, mechanical systems and control can be simulated simultaneously. A general tool that can be used interdisciplinary was required to achieve this. SIMULINK was chosen for this task.
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| 50. |
- Andersson, Arne, et al.
(författare)
-
Fusion trees can be implemented with AC0 instructions.
- 1999
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Ingår i: Theoretical Computer Science. ; 205, s. 337-344
-
Tidskriftsartikel (refereegranskat)abstract
- Addressing a problem of Fredman and Willard, we implement fusion trees in deterministic linear space using AC^o instructions only. More precisely, we show that a subset of {0,...,2^(w-1)} of size n can be maintained using linear space under insertion, deletion, predecessor, and successor queries, with O(log n/loglog n) amortized time per operation on a RAM with word size w, where the only computational instructions allowed on the RAM are fuinctions in AC^0. The AC^0 instructions used are not all available on today's computers.
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