| 230901. |
- Nordman, Hans, 1957, et al.
(författare)
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Influence of magnetic shear on impurity transport
- 2007
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Ingår i: Proceedings of 3rd International Technical Committee Meeting on the Theory of Plasma Instabilities, 26-28 March 2007 York, UK. ; 14:5, s. 052303-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 230902. |
- Nordman, Niklas
(författare)
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Increasing Returns to Scale and Benefits to Traffic : A Spatial General Equilibrium Analysis in the Case of Two Primary Inputs
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper considers two different benefit measures of a transportation improvement in a general equilibrium framework. A spatial general equilibrium model with three regions and two primary inputs is used to simulate the impacts of a small as well as a large investment in one single link of the network. The first approach is to measure total benefits to the economy as the change in consumer surplus under the general equilibrium demand curve for transports on the improved link. In the second approach the benefits are measured as equivalent variation aggregated across all three regions, which represent the economy-wide welfare improvement. The general equilibrium measure is then compared to the link-oriented measure through a ”true benefit multiplier”, in order to evaluate if the latter correctly captures total benefits to the economy. The simulations are performed both under the assumption of a first-best economy and when increasing returns to scale is present in the production of goods. It is found that total benefits due to the improvement can be fully captured by only considering transport demand on the improved link, given that the economy is a first-best economy. However, if increasing returns to scale is introduced into the model, the link-related measure tends to underestimate total benefits. The diversion between the two measures gradually increases as the scale parameter gets larger. The result shows that given an economy under influence of increasing returns to scale, it is highly relevant to take generated network impacts into consideration. It is also found that the level of flexibility in the economy, reflected by different values in elasticity of substitution in the production process, is a determinant factor for the benefits of an improvement.
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| 230903. |
- Nordman, Roger
(författare)
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A Common Method for Testing and Rating of Residential HP and AC Annual/Seasonal Performance: Final report : Annex 39
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this Annex, the following was aimed to be developed:1) Common calculation methods for SPF using a generalised and transparent approach, based on repeatability and reliable test data from laboratory measurements.2) Establish comprehensive test methods based on further development of existing teststandards. The test standards should include test conditions needed for the future SPF calculations.3) A method to evaluate additional heat pump performance, e.g. Carbon Footprint, Primary Energy Saving or Energy Savings.A matrix of existing standards, test methods and monitoring protocols was assembled, and similarities and differences between these were studied. A swot analysis was performed and proposals for how a harmonisation of test points for lab testing could happen were developed. By this harmonisation, manufacturers could test the performance of heat pumps in any accredited lab and then apply for all certificates that require tested performance, globally.In order to better understand the accuracy of calculation methods to predict real performance, a comparison of existing calculation methods and results from field measurements were made. All calculation methods have underestimated the SPF compared to the monitored value.This Annex has also contributed to the development of a whole new standard in the US the IHP (or multifunction HP) test standard, ANSI/ASHRAE 206-2013.Different methods to calculate and compare heat pumps with other heating technologies were also suggested in this work, mainly based on an LCA perspective, nut also models that calculates the CO2 emissions reduction, or the Primary Energy (PE) use have been proposed.The Japanese team in the Annex has proposed that test chambers should be built and instrumented in the same manner in order to minimise uncertainties between test sites.
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| 230904. |
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| 230905. |
- Nordman, Roger, 1971
(författare)
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New process integration methods for heat-saving retrofit projects in industrial systems
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- New graphical methods for HEN retrofit (further development of existing tools), release of usable excess heat and placement of supply tanks in HWWS systems have been developed. In addition, further development of the matrix method for HEN retrofit has been made. The methods have been used in case studies, both as stand-alone tools, and in different combinations.Using the advanced composite curves in combination with the matrix method in HEN retrofit give new insights on which units should be picked for retrofit, and how far the heat recovery should proceed. The extra information that has to be collected to show the placement of existing heaters and coolers give valuable inputs to this method. Calculations showed that heaters and coolers placed close to the pinch are often cheaper by a factor of two and more to retrofit.A method to show the potential to release usable excess heat at high temperature levels (but still below the pinch) has been developed. This method is based on the full set of stream data from the process, and therefore shows the total potential. Case studies have shown that much of the potential is also possible to release by making changes in the HEN with acceptable investments and PBPs.Another method, to be used in HWWS systems for different setups of tanks and different values of DTmin has also been developed. This method shows the potential usable excess heat versus temperature in this sub-system for a user-defined number of supply tanks and DTmin.By studying this sub-system, a large amount of the total potential can be exploited. This leaves the remaining process without any changes at all.A new optimisation routine has been developed and implemented into the matrix method. This method uses a recursive branch and bound algorithm to explore all relevant paths in the retrofit task. A first solution is made and taken as an upper bound to the problem. All following paths that exceed this bound is directly eliminated. The implementation has proven to be reliable and fast to use, although there are still improvements to be made.
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| 230906. |
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| 230907. |
- Nordman, Sofia
(författare)
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Identification of susceptibility genes in type 2 diabetes
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Identification of the susceptibility genes will offer better understanding of molecular mechanisms underlying T2D pathogenesis, and subsequently may lead to development of novel therapeutic approaches. This thesis mainly concerns the genetic association study of four candidate genes. They are selected from a region in chromosome 10q linked to T2D or based on involvement of the candidates in specific pathways related to T2D. IDE plays a principal role in the proteolysis of several peptides in addition to insulin. The gene resides in a region of chromosome 10q linked to T2D. Fourteen SNPs in the IDE and IDE-HHEX regions were genotyped in 321 IGT and 403 NGT subjects selected from SDPP. The analyses of diplotypes (haplotypic genotypes) containing three tag SNPs provided evidence of the association with fasting plasma insulin levels, 2h plasma insulin levels, HOMA-IR and BMI in men, and suggested that the polymorphisms in/near the IDE gene contribute to variance in plasma insulin levels and correlated traits. The TCF7L2 gene is also located in the region of chromosome 10q. Five SNPs in the gene were genotyped in 243 T2D patients and 528 NGT subjects, and they were Swedish men. SNPs rs7901695, rs4506565, rs7903146 and rs12255372 are strongly associated with T2D. As to rs7903146, T2D patients carrying genotypes CT or TT had higher fasting plasma glucose levels, lower HOMA-β index and BMI compared to the patients carrying CC genotype. Furthermore, NGT subjects carrying the risk alleles of SNPs rs7901695 and rs4506565 demonstrated a more pronounced increase in fasting plasma glucose levels during the follow-up period. The study consistently indicated that TCF7L2 has a crucial contribution to impaired insulin secretion underlining the development of T2D. In order to evaluate whether Leu7Pro (T1128C) polymorphism in the NPY gene contributes to the development of T2D, genotyping of this SNP in 263 T2D patients, 309 IGT and 469 NGT subjects was performed. This SNP was significantly associated with IGT and T2D among Swedish men but not women. The carriers with TC and CC genotypes in male IGT subjects had significantly higher fasting plasma glucose in comparison with the TT carriers. A previous study using the Goto-Kakizaki rat implicated that AC3 may be a candidate for T2D. The variation screening in the putative promoter was performed and a novel variant -17A/T was identified. Genotyping of 14 SNPs covering the gene, including the novel variant, was performed in male subjects, including 243 T2D and 188 NGT. Interestingly, SNPs rs2033655 C/T and rs1968482 A/G were significantly associated with T2D patients with BMI ≥30 kg/m2. Further genotyping and analysis in 199 male obese subjects with NGT demonstrated that these two polymorphisms were strongly associated with obesity. The present study thus provides the first evidence that AC3 polymorphisms confer the risk susceptibility to obesity in Swedish men with and without T2D. In conclusion, this thesis has contributed with information on the role of the IDE, TCF7L2 and NPY genes in the development of T2D and/or control of insulin levels. AC3 may play a role in the development of obesity with and without T2D.
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| 230908. |
- Nordman, Tomas
(författare)
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In vitro studies on the biosynthesis and reduction of ubiquinone
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the role of ubiquinone, the only endogenously synthesised lipid soluble antioxidant, in the cellular defence against peroxidation of proteins and lipids. The aims of the present investigations were to study the biosynthesis of ubiquinone in two different organelle fractions, i.e. microsomes and peroxisomes and to characterise the enzyme reactions of the three flavoenzymes, hpoamide dehydrogenase, glutathione reductase and thioredoxin reductase in the reduction of ubiquinone. A semipreparative HPLC method was established to rapidly isolate different polyprenols with high purity. The isolated compounds could be used for studies of different enzyme reactions in the mevalonate pathway, and as standards for quantitative HPLC-analysis. Compared to conventional chromatographic methods this new technique was much more rapid and polyprenols with higher purity was isolated. It was demonstrated that both peroxisomes and microsomes were involved in the biosynthesis of ubiquinone. Two enzymes involved in the synthesis of ubiquinone, trans-prenyltransferase and nonaprenyl-4-hydroxybenzoate (NPHB)-transferase, were investigated. The results clearly showed differences in the regulation of the synthesis of ubiquinone in those organelles. The specific activity of trans-prenyltransferase in peroxisomes was 30% of the total activity found in both organelles. The characteristics of the regeneration of ubiquinol by the flavoenzymes, hpoamide dehydrogenase, glutathione reductase and thioredoxin reductase were investigated. These enzymes belong to the same family of enzymes and are defined as homodimeric pyridine nucleotide-disulfide oxidoreductases. The reduction of ubiquinone by Hpoamide dehydrogenase and glutathione reductase was shown to be highly elevated by addition of zinc to the reaction mixture, whereas this reaction by thioredoxin reductase was inhibited by zinc. For Hpoamide dehydrogenase and glutathione reductase the pH optimum for the reaction was found at acidic pH, but at physiological pH for thioredoxin reductase. The reduction of ubiquinone by thioredoxin reductase was confirmed to be selenium dependent by use of full-length bovine and rat, E. coli (lacking selenocysteine), recombinant human (selenocysteine replaced by alanine), and truncated rat thioredoxin reductases, as well as with stable cell lines overexpressing thioredoxin reductase. Altogether, the novel biological findings in this thesis are that; ubiquinone is not only synthesised in microsomes but also to a high extent in peroxisomes; ubiquinone is efficiently reduced by glutathione reductase and thioredoxin reductase; the reduction of ubiquinone by thioredoxin reductase is entirely selenium dependent.
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| 230909. |
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| 230910. |
- Nordmark, Anna
(författare)
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Functional features of human cytochrome P450 1A2 : with special focus on caffeine and melatonin metabolism
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- CYP1A2 is one of the major cytochrome P450 enzymes in the liver and metabolises drugs such as caffeine, clozapine, tacrine, and theophylline. CYP1A2 also has a role in chemical carcinogenesis due to its activation of procarcinogens, such as heterocyclic amines and arylamines. Caffeine is extensively used to assess CYP1A2 activity. A simplified phenotyping methodology based on dietary caffeine and random urine collection was validated against a standardised methodology. The correlation coefficient between the two estimates of the CYP1A2 phenotype was 0. 9 1. The random phenotyping method was used to investigate CYP1A2 activity as risk factor for normal karyotype spontaneous abortion, and whether it would modify the effect of caffeine on abortion risk. The findings indicate that high CYP1A2 activity may increase the risk of spontaneous abortion, independently or by modifying the effect of caffeine. The random CYP1A2 phenotyping method was also used to study the inducing effect of the IF-allele on CYP1A2 activity in non-smoking and smoking pregnant women. The results did not confirm an increased induction by the mutation on CYP1A2 activity in pregnant women. It is of interest to find additional probe drugs for assessment of CYP1A2 activity. Melatonin has been suggested as an alternative. Its 6-hydroxylation was validated in vitro as a marker reaction for CYP1A2. The result showed that melatonin has a high affinity for CYP1A2 and that the contribution of other P450 enzymes was negligible. This supports earlier studies that melatonin could serve as an alternative probe for CYP1A2 activity. To evaluate the usefulness of cryopreserved human liver slices for drug metabolic studies, the intrinsic formation clearance of paraxanthine and 6-hydroxymelatonin were studied in slices and microsomes and the data were scaled to predict the in vivo clearance. Data from human liver microsomes underestimated the in vivo clearance of melatonin and this was also true for the cryopreserved liver slices. For caffeine there was a good agreement between the data generated in microsomes and in vivo clearance. These studies show that a simplified phenotyping methodology can be used in larger studies to assess CYP1A2 activity. It seems that melatonin may serve as an alternative to caffeine as a marker reaction for CYP1A2 although in vivo studies are needed to confirm this. Cryopreserved liver slices as an in vitro system are promising but require further development.
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