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- Andersson, Christian, et al.
(författare)
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Classification of power system stability using support vector machines
- 2005
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Ingår i: IEEE Power Engineering Society General Meeting, 2005. ; 1, s. 650-655
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Konferensbidrag (refereegranskat)abstract
- The last years' blackouts have indicated that even when a lot of data is available, the operators at different centers do not take the proper actions in time. This depends partly on the reorganization of the centers after the deregulation and partly on the lack of reliable supportive applications when the system is close to instability. This paper uses a novel technique based on support vector machines, SVM, in order to classify, if the power system can withstand a (n-1)-fault during a variety of operational conditions. The support vectors can be used on-line in order to determine if the system is moving into dangerous conditions and support the operators on an early stage, so proper actions can be made. This paper also shows that the scaling of the variables is important for good results. A new technique for finding the most important variables to measure or supervise is also presented.
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- Andersson, H., et al.
(författare)
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Transcriptional profiling of the peripheral blood response during tularemia
- 2006
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Ingår i: Genes and Immunity. - : Springer Science and Business Media LLC. - 1466-4879 .- 1476-5470. ; 7:6, s. 503-513
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Tidskriftsartikel (refereegranskat)abstract
- Tularemia is a febrile disease caused by the highly contagious bacterium Francisella tularensis. We undertook an analysis of the transcriptional response in peripheral blood during the course of ulceroglandular tularemia by use of Affymetrix microarrays comprising 14,500 genes. Samples were obtained from seven individuals at five occasions during 2 weeks after the first hospital visit and convalescent samples 3 months later. In total, 265 genes were differentially expressed, 95 of which at more than one time point. The differential expression was verified with real-time quantitative polymerase chain reaction for 36 genes (R(2)=0.590). The most prominent changes were noted in samples drawn on days 2-3 and a considerable proportion of the upregulated genes appeared to represent an interferon-gamma-induced response and also a proapoptotic response. Genes involved in the generation of innate and acquired immune responses were found to be downregulated, presumably a pathogen-induced event. A logistic regression analysis revealed that seven genes were good predictors of the early phase of tularemia. This is the first description of the transcriptional host response to ulceroglandular tularemia and the study has identified gene subsets relevant to the pathogenesis of the disease and subsets that may serve as early diagnostic biomarkers.
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- Björck, M, et al.
(författare)
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Twenty years with the Swedvasc Registry.
- 2008
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Ingår i: European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery. - : Elsevier BV. - 1532-2165 .- 1078-5884. ; 35:2, s. 129-30
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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- Borodina, I., et al.
(författare)
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Metabolic engineering of streptomyces
- 2009
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Ingår i: The Metabolic Pathway Engineering Handbook: Fundamentals. - 9781439802977 ; , s. 24-1-24-30
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Some of the common soil microorganisms are actinomycetes, Gram-positive bacteria with high GC content. Because of their mycelial habit they were initially believed to be fungi, which reected in their name (mucus (lat.) means fungus). In 1939, one year before rediscovery of penicillin by Florey and Chain, soil microbiologist Waksman has set his lab on a quest for new antimicrobial drugs. From the previous studies he knew that actinomycetes can inhibit the growth of other soil bacteria through secretion of bioactive compounds, which he named “antibiotics” (anti (lat.) against, bio (lat.) life). Systematic search for antibiotics produced by actinomycetes resulted in the discovery of actinomycin (1940), clavacin, and streptothricin (1942), all of them sadly turned out to be toxic in animal tests. In 1943 Waksman’s student Schatz isolated streptomycin-producing strain of Streptomyces griseus.1 Streptomycin was not particularly toxic to animals and humans, but remarkably was the rst compound active against tuberculosis bacteria. Many pharmaceutical companies and research laboratories started to collect soil samples from all over the world in search of antibiotics-producing organisms. Most of the discoveries were made in the rst ten years of the “hunt,” the larger part involved Streptomyces species. Streptomyces is a genus in the genera of actinomycetes, many of these bacteria produce volatile compounds that give the earth its characteristic odor. Streptomyces proved to be an excellent source of secondary metabolites, including antibiotics, anticancerous agents, antihelmintic drugs, and other useful compounds (Table 24.1). At present more than half of antibiotics in clinical use are produced in Streptomyces species.
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- Eliasson, A. C., et al.
(författare)
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The Manual Ability Classification System (MACS) for children with cerebral palsy: scale development and evidence of validity and reliability
- 2006
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Ingår i: Dev Med Child Neurol. - 0012-1622 .- 1469-8749. ; 48:7, s. 549-54
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Tidskriftsartikel (refereegranskat)abstract
- The Manual Ability Classification System (MACS) has been developed to classify how children with cerebral palsy (CP) use their hands when handling objects in daily activities. The classification is designed to reflect the child's typical manual performance, not the child's maximal capacity. It classifies the collaborative use of both hands together. Validation was based on the experience within an expert group, a review of the literature, and thorough analysis of children across a spectrum of function. Discussions continued until consensus was reached, first about the constructs, then about the content of the five levels. Parents and therapists were interviewed about the content and the description of levels. Reliability was tested between pairs of therapists for 168 children (70 females, 98 males; with hemiplegia [n=52], diplegia [n=70], tetraplegia [n=19], ataxia [n=6], dyskinesia [n=19], and unspecified CP [n=2]) between 4 and 18 years and between 25 parents and their children's therapists. The results demonstrated that MACS has good validity and reliability. The intraclass correlation coefficient between therapists was 0.97 (95% confidence interval 0.96-0.98), and between parents and therapist was 0.96 (0.89-0.98), indicating excellent agreement.
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- Eliasson, B, et al.
(författare)
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Instability and dynamics of two nonlinearly coupled laser beams in a two-temperature electron plasma
- 2006
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American physical society. - 1539-3755 .- 1550-2376. ; 74:4
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Tidskriftsartikel (refereegranskat)abstract
- We consider nonlinear interactions between two colliding laser beams in an electron plasma, accounting for the relativistic electron mass increase in the laser fields and radiation pressure driven electron-acoustic (EA) perturbations that are supported by hot and cold electrons. By using the hydrodynamic and Maxwell equations, we obtain the relevant equations for nonlinearly coupled laser beams and EA perturbations. The coupled equations are then Fourier analyzed to obtain a nonlinear dispersion relation. The latter is numerically solved to show the existence of new classes of the parametric instabilities in the presence of two colliding laser beams in a two-electron plasma. The dynamics of nonlinearly coupled laser beams in our electron plasma is also investigated. The results should be useful in understanding the nonlinear propagation characteristics of multiple electromagnetic beams in laser-produced plasmas as well as in space plasmas.
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- Eliasson, B., et al.
(författare)
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Simulation study of surfing acceleration in magnetized space plasmas
- 2005
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- We present a numerical study of the surfing mechanism in which electrons are trapped in Bernstein-Greene-Kruskal (BGK) modes, and are accelerated across the magnetic field direction by the Lorentz force in magnetized space plasmas. The BGK modes are the product of an ion-beam Buneman instability that excites large-amplitude electrostatic upper-hybrid waves in the plasma. Our study, which is performed with particle-in-cell (PIC) and Vlasov codes, reveals the stability of the BGK mode as a function of the magnetic field strength and the ion beam speed. It is found that the surfing acceleration is more effective for a weaker magnetic field owing to the longer lifetime of the BGK modes. The importance of our investigation to electron acceleration in astrophysical environments has been emphasized. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
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- Eliasson, B., et al.
(författare)
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Simulation study of the interaction between large-amplitude HF radio waves and the ionosphere
- 2007
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 34:L0610
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Tidskriftsartikel (refereegranskat)abstract
- The time evolution of a large-amplitude electromagnetic (EM) wave injected vertically into the overhead ionosphere is studied numerically. The EM wave has a carrier frequency of 5 MHz and is modulated as a Gaussian pulse with a width of approximately 0.1 milliseconds and a vacuum amplitude of 1.5 V/m at 50 km. This is a fair representation of a modulated radio wave transmitted from a typical high-power HF broadcast station on the ground. The pulse is propagated through the neutral atmosphere to the critical points of the ionosphere, where the L-O and R-X modes are reflected, and back to the neutral atmosphere. We observe mode conversion of the L-O mode to electrostatic waves, as well as harmonic generation at the turning points of both the R-X and L-O modes, where their amplitudes rise to several times the original ones. The study has relevance for ionospheric interaction experiments in combination with ground-based and satellite or rocket observations.
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