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Search Results: 1 - 10 of 15 matches for " Tarjei Skotheimsvik "
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Implementation of recommended trauma system criteria in south-eastern Norway: a cross-sectional hospital survey
Thomas Kristiansen, Kjetil G Ringdal, Tarjei Skotheimsvik, Halvor K Salthammer, Christine Gaarder, P?l A N?ss, Hans M Lossius
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine , 2012, DOI: 10.1186/1757-7241-20-5
Abstract: Recommendations for a national trauma system in Norway were published in 2007. We wanted to assess the level of implementation of these recommendations.A survey of all acute care hospitals that receive severely injured patients in the south-eastern health region of Norway was conducted. A structured questionnaire based on the 2007 national recommendations was used in a telephone interview of hospital trauma personnel between January 17 and 21, 2011. Seventeen trauma system criteria were identified from the recommendations.Nineteen hospitals were included in the study and these received more than 2000 trauma patients annually via their trauma teams. Out of the 17 criteria that had been identified, the hospitals fulfilled a median of 12 criteria. Neither the size of the hospitals nor the distance between the hospitals and the regional trauma centre affected the level of trauma resources available. The hospitals scored lowest on the criteria for transfer of patients to higher level of care and on the training requirements for members of the trauma teams.Our study identifies a major shortcoming in the efforts of regionalizing trauma in our region. The findings indicate that training of personnel and protocols for inter-hospital transfer are the major deficiencies from the national trauma system recommendations. Resources for training of personnel partaking in trauma teams and development of inter-hospital transfer agreements should receive immediate attention.Formalized trauma systems were described more than three decades ago [1]. Supported by an increasing amount of empirical evidence, the benefit of trauma systems have been widely accepted among trauma care providers [2-5]. In spite of this, relatively few regions internationally have fully implemented the trauma system concepts. Factors that make trauma system implementation challenging, like financial costs, lack of political will, and resistance against centralizing health care services, have been identified [6-9]
Utilizing MATPOWER in Optimal Power Flow
Tarjei Kristiansen
Modeling, Identification and Control , 2003, DOI: 10.4173/mic.2003.1.5
Abstract: This paper shows how MATPOWER, a MATLAB Power System Simulation Package can be used for optimal power flow (OPF) simulations. MATPOWER is a package of MATLAB files for solving power flow and optimal power flow problems. It is a simulation tool for researchers and educators which is easy to use and modify. An OPF simulation gives the active/reactive power generated and purchased at each bus and the nodal prices. The nodal prices are of special interest because they reflect the marginal generation and load at each bus (node). These prices are also called locational prices and are found to be the optimal prices, maximizing social welfare and taking transmission constraints into account. They can provide the right incentives to market players and to society. When transmission congestion is present this creates market inefficiency, since cheap distant generation may be replaced with more expensive local generation. We are especially interested in OPF as utilized by a centralized dispatcher, and we also describe the features relevant for the Norwegian and Nordic markets. We optimize three cases and analyze the economic consequences of different network topologies and transmission congestion.
What makes us human?
Tarjei S Mikkelsen
Genome Biology , 2004, DOI: 10.1186/gb-2004-5-8-238
Abstract: In a recent paper in Nature [1], the International Chimpanzee Chromosome 22 Consortium describes the sequencing and initial analysis of chromosome 22 of the chimpanzee Pan troglodytes (PTR22), the ortholog of human chromosome 21 (HSA21, which is involved in the trisomy that leads to Down syndrome). A whole-genome shotgun draft assembly of the entire chimpanzee genome was made public by a US-based consortium in 2003 [2], but the sequence published by Watanabe et al. [1] - which was sequenced from bacterial artificial chromosome clones rather than by whole-genome shotgun - represents the first 'finished' chimpanzee chromosome, meaning that its completeness, contiguity and error rates are comparable to the current human genome sequence [3]. In addition to being a valuable quality control for the whole-genome shotgun assembly, finished sequence is better suited for studying insertions, deletions and other structural variation between the human and chimpanzee genomes. The analysis by Watanabe et al. [1] also constitutes the first complete and unbiased comparison of a human and a chimpanzee chromosome at the sequence level.Watanabe et al. [1] found that PTR22 and HSA21 differ at approximately 1.44% of their 33 million aligned nucleotides. In addition, they found 68,000 insertions or deletions (indels), the vast majority less than 300 bp in size. The number of indels accumulated over the time since humans and chimpanzees diverged is therefore approximately one seventh the number of point mutations in the same period; as several nucleotides are affected by each indel event, however, this result confirms previous estimates [4] that indels are a major source of sequence divergence between humans and chimpanzees. Comparison of the human-chimpanzee indels to gorilla and orangutan sequences suggests that both PTR22 and HSA21 have undergone a small net decrease in size since speciation, but it is unclear whether this observation can be extrapolated to the respective complete geno
Relaxed dispersion constraints and metamaterial effective parameters with physical meaning for all frequencies
Christopher A. Dirdal,Tarjei Bondevik,Johannes Skaar
Physics , 2014, DOI: 10.1103/PhysRevB.91.134102
Abstract: Metamaterial effective parameters may exhibit freedom from typical dispersion constraints. For instance, the emergence of a magnetic response in arrays of split-ring resonators for long wavelengths cannot be attained in a passive continuous system obeying the Kramers-Kronig relations. We characterize such freedom by identifying the three possible asymptotes which effective parameters can approach when analytically continued. Apart from their dispersion freedom, we also demonstrate that the effective parameters may be redefined in such a way that they have a certain physical meaning for all frequencies. There exists several possible definitions for the effective permittivity and permeability whereby this is achieved, thereby giving several possible frequency variations for high frequencies, while nevertheless converging to the same dispersion for long wavelengths.
Calculation of the Minimum Ignition Energy based on the ignition delay time
Jens Tarjei Jensen,Nils Erland L. Haugen,Natalia Babkovskaia
Physics , 2011,
Abstract: The Minimum Ignition Energy (MIE) of an initially Gaussian temperature profile is found both by Direct Numerical Simulations (DNS) and from a new novel model. The model is based on solving the heat diffusion equation in zero dimensions for a Gaussian velocity distribution. The chemistry is taken into account through the ignition delay time, which is required as input to the model. The model results reproduce the DNS results very well for the Hydrogen mixture investigated. Furthermore, the effect of ignition source dimensionality is explored, and it is shown that for compact ignition kernels there is a strong effect on dimensionality. Here, three, two and one dimensional ignition sources represent a spherical kernel, a long spark and an ignition sheet, respectively.
Norwegian Hip Fracture Register
Jan-Erik Gjertsen,Jonas Fevang,Tarjei Vinje,Lars Birger Enges?ter
Norsk Epidemiologi , 2011,
Abstract:
The Norwegian Hip Fracture Register / Nasjonalt Hoftebruddregister
Jan-Erik Gjertsen,Jonas Fevang,Tarjei Vinje,Lars Birger Enges?ter
Norsk Epidemiologi , 2009,
Abstract: Background: Every year 9000 patients in Norway are operated due to hip fractures. A hip fracture is a diagnosis associated with high mortality and morbidity. The patient population is increasing and large resources are used in the treatment of these patients. There is no consensus in Norway stating the preferred method of treatment. The Norwegian Hip Fracture Register was founded at the National Arthroplasty Register 1. January 2005. Material and methods: We have established contacts at every hospital in Norway that perform surgery for hip fractures. After surgery, the surgeon fills in a standardized form, which is sent to the register once a month. On the form there are both patient- and procedure-related questions. To ensure accurate information on the implants, the surgeons use stickers with catalogue numbers supplied by the manufacturers. After four and twelve months a questionnaire is sent to each patient. Among other questions we used the Norwegian translation of the EuroQol- 5D (EQ-5D) which is a non-disease-specific instrument for describing and valuing health-related quality of life. All the results are stored in our database. The information is linked to the Norwegian Registry of Vital Statistics by use of the unique identification number assigned for each resident of Norway. Results: After one year of registration 100% of the hospitals are reporting to the register. 51% of the patients have answered the questionnaire. We have included 5668 primary operated patients (mean age 80.3 years and 72.5% females) and 500 revisions. So far no difference in mortality between patients treated with a screw fixation and patients treated with a hemiarthroplasty has been found. Discussion: With longer follow-up we will be able to do survival analyses on the different implants. Using the EQ-5D we will also look for differences in quality of life after four and twelve months. We have already planned several articles and publications. Bakgrunn: Hvert r opereres det i Norge ca. 9000 pasienter for hoftebrudd. Hoftebrudd er en diagnose assosiert med h y mortalitet og morbiditet. Det er ingen konsensus i Norge om hvordan hoftebrudd, og spesielt de dislokerte l rhalsbruddene, skal opereres. Nasjonalt Hoftebruddregister ble 01.01.05 opprettet ved Nasjonalt Kompetansesenter for Leddproteser for kvalitetssikre behandlingen av pasienter med hoftebrudd. Materiale og metode: Det er opprettet kontaktpersoner til registeret ved alle sykehus hvor det opereres hoftebrudd. Etter hver operasjon fyller operat r ut et operasjonsskjema som sendes til registeret. I tillegg til pa
Analysis of the Effects of Five Factors Relevant to In Vitro Chondrogenesis of Human Mesenchymal Stem Cells Using Factorial Design and High Throughput mRNA-Profiling
Rune B. Jakobsen, Esben ?strup, Xiaolan Zhang, Tarjei S. Mikkelsen, Jan E. Brinchmann
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096615
Abstract: The in vitro process of chondrogenic differentiation of mesenchymal stem cells for tissue engineering has been shown to require three-dimensional culture along with the addition of differentiation factors to the culture medium. In general, this leads to a phenotype lacking some of the cardinal features of native articular chondrocytes and their extracellular matrix. The factors used vary, but regularly include members of the transforming growth factor β superfamily and dexamethasone, sometimes in conjunction with fibroblast growth factor 2 and insulin-like growth factor 1, however the use of soluble factors to induce chondrogenesis has largely been studied on a single factor basis. In the present study we combined a factorial quality-by-design experiment with high-throughput mRNA profiling of a customized chondrogenesis related gene set as a tool to study in vitro chondrogenesis of human bone marrow derived mesenchymal stem cells in alginate. 48 different conditions of transforming growth factor β 1, 2 and 3, bone morphogenetic protein 2, 4 and 6, dexamethasone, insulin-like growth factor 1, fibroblast growth factor 2 and cell seeding density were included in the experiment. The analysis revealed that the best of the tested differentiation cocktails included transforming growth factor β 1 and dexamethasone. Dexamethasone acted in synergy with transforming growth factor β 1 by increasing many chondrogenic markers while directly downregulating expression of the pro-osteogenic gene osteocalcin. However, all factors beneficial to the expression of desirable hyaline cartilage markers also induced undesirable molecules, indicating that perfect chondrogenic differentiation is not achievable with the current differentiation protocols.
Altered Chromatin Occupancy of Master Regulators Underlies Evolutionary Divergence in the Transcriptional Landscape of Erythroid Differentiation
Jacob C. Ulirsch,Jessica N. Lacy,Xiuli An,Narla Mohandas,Tarjei S. Mikkelsen,Vijay G. Sankaran
PLOS Genetics , 2014, DOI: doi/10.1371/journal.pgen.1004890
Abstract: Erythropoiesis is one of the best understood examples of cellular differentiation. Morphologically, erythroid differentiation proceeds in a nearly identical fashion between humans and mice, but recent evidence has shown that networks of gene expression governing this process are divergent between species. We undertook a systematic comparative analysis of six histone modifications and four transcriptional master regulators in primary proerythroblasts and erythroid cell lines to better understand the underlying basis of these transcriptional differences. Our analyses suggest that while chromatin structure across orthologous promoters is strongly conserved, subtle differences are associated with transcriptional divergence between species. Many transcription factor (TF) occupancy sites were poorly conserved across species (~25% for GATA1, TAL1, and NFE2) but were more conserved between proerythroblasts and cell lines derived from the same species. We found that certain cis-regulatory modules co-occupied by GATA1, TAL1, and KLF1 are under strict evolutionary constraint and localize to genes necessary for erythroid cell identity. More generally, we show that conserved TF occupancy sites are indicative of active regulatory regions and strong gene expression that is sustained during maturation. Our results suggest that evolutionary turnover of TF binding sites associates with changes in the underlying chromatin structure, driving transcriptional divergence. We provide examples of how this framework can be applied to understand epigenomic variation in specific regulatory regions, such as the β-globin gene locus. Our findings have important implications for understanding epigenomic changes that mediate variation in cellular differentiation across species, while also providing a valuable resource for studies of hematopoiesis.
The Case for Selection at CCR5-Δ32
Pardis C. Sabeti,Emily Walsh,Steve F. Schaffner,Patrick Varilly,Ben Fry,Holli B. Hutcheson,Mike Cullen,Tarjei S. Mikkelsen,Jessica Roy,Nick Patterson,Richard Cooper,David Reich,David Altshuler,Stephen O'Brien,Eric S. Lander
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0030378
Abstract: The C-C chemokine receptor 5, 32 base-pair deletion (CCR5-Δ32) allele confers strong resistance to infection by the AIDS virus HIV. Previous studies have suggested that CCR5-Δ32 arose within the past 1,000 y and rose to its present high frequency (5%–14%) in Europe as a result of strong positive selection, perhaps by such selective agents as the bubonic plague or smallpox during the Middle Ages. This hypothesis was based on several lines of evidence, including the absence of the allele outside of Europe and long-range linkage disequilibrium at the locus. We reevaluated this evidence with the benefit of much denser genetic maps and extensive control data. We find that the pattern of genetic variation at CCR5-Δ32 does not stand out as exceptional relative to other loci across the genome. Moreover using newer genetic maps, we estimated that the CCR5-Δ32 allele is likely to have arisen more than 5,000 y ago. While such results can not rule out the possibility that some selection may have occurred at C-C chemokine receptor 5 (CCR5), they imply that the pattern of genetic variation seen atCCR5-Δ32 is consistent with neutral evolution. More broadly, the results have general implications for the design of future studies to detect the signs of positive selection in the human genome.
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