| 1. |
- Ekoff, Maria, et al.
(författare)
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The BH3-only protein Puma plays an essential role in cytokine deprivation-induced apoptosis of mast cells
- 2007
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 110:9, s. 3209-3217
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells play critical roles in the regulation of inflammation. One characteristic feature of mast cells is their relatively long lifespan in vivo. Members of the Bcl-2 protein family are regulators of cell survival and apoptosis, where the BH3-only proteins are critical proapoptotic proteins. In this study we investigated the role of the BH3-only proteins Noxa, Bad, Bim, Bmf, Bid, and Puma in apoptosis of mucosal-like mast cells (MLMCs) and connective tissue-like mast cells (CTLMCs). We demonstrate that Puma is critical for the induction of mast-cell death following cytokine deprivation and treatment with the DNA-damaging agent etoposide in MLMCs and CTLMCs. Using p53-/- mast cells, we found that cytokine deprivation-induced apoptosis, in contrast to that elicited by etoposide, is p53-independent. Interestingly, mast cells deficient in FOXO3a, previously proposed as a transcription factor for Puma induction in response to growth factor deprivation, were markedly resistant to cytokine withdrawal compared with wildtype cells. Moreover, overexpression of phosphorylation-deficient, constitutively active FOXO3a caused an up-regulation of Puma. In conclusion, our data demonstrate a pivotal role for Puma in the regulation of cytokine deprivation-induced mast-cell apoptosis and suggest a plausible role for Puma in the regulation of mast cell numbers in vivo. © 2007 by The American Society of Hematology.
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| 2. |
- Höglund, Andreas, 1980-, et al.
(författare)
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Myc sensitizes p53-deficient cancer cells to the DNA-damaging effects of the DNA methyltransferase inhibitor decitabine
- 2009
-
Ingår i: Blood. - : The American Society of Hematology. - 0006-4971 .- 1528-0020. ; 113:18, s. 4281-4288
-
Tidskriftsartikel (refereegranskat)abstract
- Decitabine (also referred to as 5-aza-2'-deoxycytidine) is a drug that has recently been approved by the Food and Drug Administration (FDA) for the treatment of myelodysplastic syndrome (MDS). The mechanism of action is believed to be the blocking of DNA methylation and thereby reactivating silenced genes involved in harnessing MDS. When analyzing reactivation of genes involved in Burkitt lymphoma (BL), we discovered that decitabine also sensitizes tumor cells by inducing DNA damage. This sensitization is grossly augmented by the MYC oncogene, which is overexpressed in BL, and occurs in cells lacking a functional p53 tumor suppressor pathway. In p53-deficient BL cells and p53(-/-) mouse embryo fibroblasts, Myc overrides a transient G2-block exerted by decitabine via activation of Chk1. This triggers aneuploidy and cell death that correlates with, but can occur in the absence of, Epstein-Barr virus (EBV) reactivation, caspase activation, and/or expression of the BH3-only protein Puma. In vivo modeling of Myc-induced lymphoma suggests that decitabine constitutes a potential new drug against lymphoma that would selectively sensitize tumor cells but spare normal tissue.
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| 3. |
- Mathsson, Linda, et al.
(författare)
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Cryoglobulin-induced cytokine production via FcgammaRIIa: inverse effects of complement blockade on the production of TNF-alpha and IL-10. Implications for the growth of malignant B-cell clones.
- 2005
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Ingår i: British Journal of Haematology. ; 129:6, s. 830-838
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Tidskriftsartikel (refereegranskat)abstract
- Monoclonal antibodies produced by patients with lymphoproliferative diseases sometimes appear as cryoglobulins (CG), immunoglobulins (Ig) that reversibly agglutinate and form immune complexes (IC) when cooled below normal body temperature or through variation in pH and ionic strength. In accordance with our findings of IC-induced cytokine production from peripheral blood mononuclear cells (PBMC) in systemic lupus erythematosus, we investigated whether CG can also induce cytokine production. One IgG and one IgM type I CG from two patients with multiple myeloma and Waldenstrom's macroglobulinaemia were individually purified and added to PBMC cultures. In separate experiments temperature and ionic strength were varied, or FcgammaRIIa, FcgammaRIII and complement activation were blocked; supernatant cytokine levels were then determined by enzyme-linked immunosorbent assay. CG-induced cytokine production from monocytes varied with precipitation induced by changes in temperature and ionic strength and was mediated via FcRIIa- and complement-dependent mechanisms. Complement blockade resulted in increased IgG CG-induced interleukin (IL)-10 production that was inversely correlated with decreased production of tumour necrosis factor-alpha. CG-induced IL-10 might be a growth factor for malignant B-lymphocytes in CG-associated lymphoproliferative diseases with constant complement consumption. Knowledge of mechanisms underlying CG-induced cytokine production can be useful for designing treatments for type I CG-associated pathology in lymphoproliferative diseases.
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| 4. |
- Nilsson, K. Peter R., et al.
(författare)
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Imaging distinct conformational states of amyloid-beta fibrils in Alzheimer's disease using novel luminescent probes
- 2007
-
Ingår i: ACS Chemical Biology. - : American Chemical Society (ACS). - 1554-8929 .- 1554-8937. ; 2:8, s. 553-560
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Tidskriftsartikel (refereegranskat)abstract
- Using luminescent conjugated polyelectrolyte probes (LCPs), we demonstrate the possibility to distinguish amyloid-β 1–42 peptide (Aβ1–42) fibril conformations, by analyzing in vitro generated amyloid fibrils of Aβ1–42 formed under quiescent and agitated conditions. LCPs were then shown to resolve such conformational heterogeneity of amyloid deposits in vivo. A diversity of amyloid deposits depending upon morphology and anatomic location was illustrated with LCPs in frozen ex vivo brain sections from a transgenic mouse model (tg-APP swe) of Alzheimer’s disease. Comparative LCP fluorescence showed that compact-core plaques of amyloid β precursor protein transgenic mice were composed of rigid dense amyloid. A more abundant form of amyloid plaque displayed morphology of a compact center with a protruding diffuse exterior. Surprisingly, the compact center of these plaques showed disordered conformations of the fibrils, and the exterior was composed of rigid amyloid protruding from the disordered center. This type of plaque appears to grow from more loosely assembled regions toward solidified amyloid tentacles. This work demonstrates how application of LCPs can prove helpful to monitor aggregate structure of in vivo formed amyloid deposits such as architecture, maturity, and origin.
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| 5. |
- Nilsson, Peter, et al.
(författare)
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Imaging distinct conformational states of amyloid-β fibrils in Alzheimer's disease using novel luminescent probes
- 2007
-
Ingår i: ACS Chemical Biology. - : American Chemical Society (ACS). - 1554-8929 .- 1554-8937. ; 2:8, s. 553-560
-
Tidskriftsartikel (refereegranskat)abstract
- Using luminescent conjugated polyelectrolyte probes (LCPs), we demonstrate the possibility to distinguish amyloid-β 1-42 peptide (Aβ1-42) fibril conformations, by analyzing in vitro generated amyloid fibrils of Aβ1-42 formed under quiescent and agitated conditions. LCPs were then shown to resolve such conformational heterogeneity of amyloid deposits in vivo. A diversity of amyloid deposits depending upon morphology and anatomic location was illustrated with LCPs in frozen ex vivo brain sections from a transgenic mouse model (tg-APPswe) of Alzheimer's disease. Comparative LCP fluorescence showed that compact-core plaques of amyloid β precursor protein transgenic mice were composed of rigid dense amyloid. A more abundant form of amyloid plaque displayed morphology of a compact center with a protruding diffuse exterior. Surprisingly, the compact center of these plaques showed disordered conformations of the fibrils, and the exterior was composed of rigid amyloid protruding from the disordered center. This type of plaque appears to grow from more loosely assembled regions toward solidified amyloid tentacles. This work demonstrates how application of LCPs can prove helpful to monitor aggregate structure of in vivo formed amyloid deposits such as architecture, maturity, and origin.
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| 6. |
- Nord, Andreas, et al.
(författare)
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Patterns and dynamics of rest-phase hypothermia in wild and captive blue tits during winter.
- 2009
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Ingår i: Journal of Comparative Physiology B. - : Springer Science and Business Media LLC. - 0174-1578 .- 1432-136X. ; 179, s. 737-745
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated biotic and abiotic predictors of rest-phase hypothermia in wintering blue tits (Cyanistes caeruleus) and also assessed how food availability influences nightly thermoregulation. On any given night, captive blue tits (with unrestricted access to food) remained largely homeothermic, whereas free-ranging birds decreased their body temperature (T (b)) by about 5 degrees C. This was not an effect of increased stress in the aviary as we found no difference in circulating corticosterone between groups. Nocturnal T (b) in free-ranging birds varied with ambient temperature, date and time. Conversely, T (b) in captive birds could not be explained by climatic or temporal factors, but differed slightly between the sexes. We argue that the degree of hypothermia is controlled predominantly by birds' ability to obtain sufficient energy reserves during the day. However, environmental factors became increasingly important for thermoregulation when resources were limited. Moreover, as birds did not enter hypothermia in captivity when food was abundant, we suggest that this strategy has associated costs and hence is avoided whenever resource levels permit.
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| 7. |
- Puschmann, Andreas, et al.
(författare)
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A Swedish family with de novo alpha-synuclein A53T mutation: Evidence for early cortical dysfunction.
- 2009
-
Ingår i: Parkinsonism & Related Disorders. - : Elsevier BV. - 1873-5126 .- 1353-8020. ; 15, s. 627-632
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Tidskriftsartikel (refereegranskat)abstract
- A de novo alpha-synuclein A53T (p.Ala53 Th; c.209G > A) mutation has been identified in a Swedish family with autosomal dominant Parkinson's disease (PD). Two affected individuals had early-onset (before 31 and 40 years), severe levodopa-responsive PD with prominent dysphasia, dysarthria, and cognitive decline. Longitudinal clinical follow-up, EEG, SPECT and CSF biomarker examinations suggested an underlying encephalopathy with cortical involvement. The mutated allele (c.209A) was present within a haplotype different from that shared among mutation carriers in the Italian (Contursi) and the Greek-American Family H kindreds. One unaffected family member carried the mutation haplotype without the c.209A mutation, strongly suggesting its de novo occurrence within this family. Furthermore, a novel mutation c.488G > A (p.Arg163His; R163H) in the presenilin-2 (PSEN2) gene was detected, but was not associated with disease state.
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| 8. |
- Agebro, Markus, et al.
(författare)
-
Driver preferences of steering gear ratio and steering wheel effort : A driving simulator study
- 2006
-
Ingår i: Proceedings of the FISITA World Automotive Congress, Yokohama, Japan 2006..
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Konferensbidrag (refereegranskat)abstract
- When driving an automobile, the driver has to correct the course as a result of road curvature and external disturbances. In order to make the vehicle both controllable and comfortable to drive, it is important that the steering system is designed with different drivers in mind. In this work, driver preferences of steering system characteristics is investigated by comparing standard steering wheel settings with unconventional steering gear ratio and steering wheel effort. The investigation is made using 18 test subjects in a moving base driving simulator. The evaluation includes two scenarios. In the first scenario the driver is overtaking a bus at 110 km/h when meeting traffic in the opposite lane. In the second scenario the driver is doing a manoeuvre by following a cone track at 55 km/h. To investigate if there are differences in preference of drivers with varying experience of driving, the drivers are chosen to either be low or high mileage drivers. People that drive less than 5,000 km/year are considered to be low mileage drivers, and people that drive more than 25,000 km/year are considered to be high mileage drivers. The results show that original settings of a typical passenger car, which served as reference, prove to display favourable characteristics compared to the unconventional settings investigated. However, there might be settings within the investigated intervals that can be considered superior. A distinct trend in the results is that increasing effort will lead to increased perceived stability, independent of ratio. High mileage drivers find the setting with low ratio and reference effort to possess better qualities than the reference when evaluating the attributes steering wheel force and response and only slightly less favourable properties than the reference when evaluating the attribute stability. High mileage drivers display a more distinct opinion and a higher sensitivity when evaluating the attributes. Despite the differing setup of the scenarios, many similarities can be observed when studying the results. Even though there are similarities in the results both between the scenarios and the categories of drivers, a study of the individual test subjects´ preferences reveal that several drivers prefer other settings than the reference for the investigated scenarios. Therefore, it is clear that the driver-vehicle system would benefit from tailoring the steering characteristics to the situation and driver.
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| 9. |
- Aidas, Kestutis, et al.
(författare)
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On the performance of quantum chemical methods to predict solvatochromic effects: The case of acrolein in aqueous solution.
- 2008
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 128:19, s. 1-194503
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Tidskriftsartikel (refereegranskat)abstract
- The performance of the Hartree-Fock method and the three density functionals B3LYP, PBE0, and CAM-B3LYP is compared to results based on the coupled cluster singles and doubles model in predictions of the solvatochromic effects on the vertical n-->pi(*) and pi-->pi(*) electronic excitation energies of acrolein. All electronic structure methods employed the same solvent model, which is based on the combined quantum mechanics/molecular mechanics approach together with a dynamical averaging scheme. In addition to the predicted solvatochromic effects, we have also performed spectroscopic UV measurements of acrolein in vapor phase and aqueous solution. The gas-to-aqueous solution shift of the n-->pi(*) excitation energy is well reproduced by using all density functional methods considered. However, the B3LYP and PBE0 functionals completely fail to describe the pi-->pi(*) electronic transition in solution, whereas the recent CAM-B3LYP functional performs well also in this case. The pi-->pi(*) excitation energy of acrolein in water solution is found to be very dependent on intermolecular induction and nonelectrostatic interactions. The computed excitation energies of acrolein in vacuum and solution compare well to experimental data.
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| 10. |
- Ask, Urban, 1956, et al.
(författare)
-
IT Governance in the light of Paradox - A Social System Theory Perspective
- 2006
-
Ingår i: The 40th Hawaii International Conference on System Sciences, 2007.
-
Konferensbidrag (refereegranskat)abstract
- This paper uses Niclas Luhmann's concepts of paradox and deparadoxization as a starting point for looking at IT governance within large, Swedish organizations. All in all a total of 25 organizations within both the public and private sector have been investigated through interviews with the companies Chief Information Officers. The results are presented in relation to a number of areas within the study that could be identified as dichotomies, or areas where the respondents had to deal with conflicting logics. The results are discussed in general terms in relation to IT governance practice as well as the potential value of applying Luhmann's theory of social systems to the study of IT governance
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| 11. |
- Aslund, Andreas, et al.
(författare)
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Fluorescent oligo and poly-thiophenes and their utilization for recording biological events of diverse origin-when organic chemistry meets biology.
- 2009
-
Ingår i: Journal of chemical biology. - : Springer Science and Business Media LLC. - 1864-6166 .- 1864-6158. ; 2:4, s. 161-175
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Tidskriftsartikel (refereegranskat)abstract
- The technique of using luminescent oligo-thiophenes and luminescent conjugated poly-thiophenes to monitor biological processes has gained increased interest from scientists within different research areas, ranging from organic chemistry and photo-physics to biology since its introduction. The technique is generally straightforward and requires only standard equipment, and the result is available within minutes from sample preparation. In this review, the syntheses of oligo and polythiophenes developed over the last decades are discussed. Furthermore, the utilization of these molecular agents for exploring biological events, e.g., DNA hybridization or protein misfolding events, are covered.
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| 12. |
- Berglin-Enquist, Ida, et al.
(författare)
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Murine models of acute neuronopathic Gaucher disease
- 2007
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 104:44, s. 17483-17488
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Tidskriftsartikel (refereegranskat)abstract
- Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by mutations in the glucosidase, beta, acid (GBA) gene that encodes the lysosomal enzyme glucosylceramidase (GCase). GCase deficiency leads to characteristic visceral pathology and, in some patients, lethal neurological manifestations. Here, we report the generation of mouse models with the severe neuronopathic form of GD. To circumvent the lethal skin phenotype observed in several of the previous GCase-deficient animals, we genetically engineered a mouse model with strong reduction in GCase activity in all tissues except the skin. These mice exhibit rapid motor dysfunction associated with severe neurodegeneration and apoptotic cell death within the brain, reminiscent of neuronopathic GD. In addition, we have created a second mouse model, in which GCase deficiency is restricted to neural and glial cell progenitors and progeny. These mice develop similar pathology as the first mouse model, but with a delayed onset and slower disease progression, which indicates that GCase deficiency within microglial cells that are of hematopoietic origin is not the primary determinant of the CNS pathology. These findings also demonstrate that normal microglial cells cannot rescue this neurodegenerative disease. These mouse models have significant implications for the development of therapy for patients with neuronopathic GD.
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| 13. |
- Biel, Anders, 1948, et al.
(författare)
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Emotions, Morality and Public Goods: The WTA-WTP Disparity Revisited
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Empirical evidence suggests that people´s maximum willingness to pay for having a good is often substantially lower than their minimum willingness to accept not having it, and that this discrepancy tends to be especially large when valuing public goods. This paper hypothesizes that differences in emotions (e.g. regret) and moral perceptions can account for much of this discrepancy for public goods. A simple, real-money dichotomous-choice experiment is set up to test these hypotheses, which are largely supported.
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| 14. |
- Biel, Anders, 1948, et al.
(författare)
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Religious values and environmental concern: Harmony and detachment
- 2005
-
Ingår i: Social Science Quarterly. ; 86:1, s. 178-191
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Tidskriftsartikel (refereegranskat)abstract
- The thought that environmental concern is rooted in religious beliefs and values has been raised by many writers. Different claims have been made about whether the nature of this relationship is positive or negative, and empirical evidence is mixed. In line with research on attitudes and values, the objective of this study is to examine the hypothesis that unless religious values are mentally accessible, they will not affect judgments of environmental issues. Two environmental is-sues, genetically modified crops and more traditional environmental issues, for example, air pollution from traffic, are chosen to represent accessibility and non-accessibility, respectively. A two-wave data set from a national survey is ana-lyzed. Results support the suggestion that religious values will affect the judg-ment of environmental threats of the first, but not the second issue. In conclu-sion, these findings suggest that situational cues partly determine which values embodied in religion that will influence environmental attitudes.
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| 15. |
- Bjursten, Henrik, et al.
(författare)
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Particle separation using ultrasound can be used with human shed mediastinal blood.
- 2005
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Ingår i: Perfusion. - : SAGE Publications. - 1477-111X .- 0267-6591. ; 20:1, s. 39-43
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Tidskriftsartikel (refereegranskat)abstract
- Shed mediastinal blood collected by cardiotomy suction has been shown to be a large contributor to lipid microemboli ending up in different organs. The aim of this study was to test the separation efficiency on human shed blood of a new separation method developed to meet this demand. METHODS: Shed mediastinal blood collected from the pericardial cavity of 13 patients undergoing cardiac surgery with cardiopulmonary bypass was collected. The blood was processed in an eight-channel parallel PARSUS separator, and separation efficiency was determined. RESULTS: Erythrocyte recovery, in terms of a separation ratio, varied between 68% and 91%. Minor electrolyte changes took place, where levels of sodium increased and levels of potassium and calcium decreased. CONCLUSION: This study demonstrates that PARSUS technology can be used on human shed mediastinal blood with good separation efficiency. The technology is, thereby, suggested to have future clinical relevance.
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| 16. |
- Blomberg, Jeanette, 1977-, et al.
(författare)
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Reduced FAS transcription in clones of U937 cells that have acquired resistance to Fas-induced apoptosis
- 2009
-
Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 276:2, s. 497-508
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Tidskriftsartikel (refereegranskat)abstract
- Susceptibility to cell death is a prerequisite for the elimination of tumour cells by cytotoxic immune cells, chemotherapy or irradiation. Activation of the death receptor Fas is critical for the regulation of immune cell homeostasis and efficient killing of tumour cells by apoptosis. To define the molecular changes that occur during selection for insensitivity to Fas-induced apoptosis, a resistant variant of the U937 cell line was established. Individual resistant clones were isolated and characterized. The most frequently observed defect in the resistant cells was reduced Fas expression, which correlated with decreased FAS transcription. Clones with such reduced Fas expression also displayed partial cross-resistance to tumour necrosis factor-alpha stimulation, but the mRNA expression of tumour necrosis factor receptors was not decreased. Reintroduction of Fas conferred susceptibility to Fas but not to tumour necrosis factor-alpha stimulation, suggesting that several alterations could be present in the clones. The reduced Fas expression could not be explained by mutations in the FAS coding sequence or promoter region, or by silencing through methylations. Protein kinase B and extracellular signal-regulated kinase, components of signalling pathways downstream of Ras, were shown to be activated in some of the resistant clones, but none of the three RAS genes was mutated, and experiments using chemical inhibitors could not establish that the activation of these proteins was the cause of Fas resistance as described in other systems. Taken together, the data illustrate that Fas resistance can be caused by reduced Fas expression, which is a result of an unidentified mode of regulation.
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| 17. |
- Blomquist, Tomas, et al.
(författare)
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Development of Virtual Teams and Learning Communities
- 2005
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Ingår i: Recent Research Developments in Learning Technologies. - Badajos, Spain : Formatex Research Center. ; , s. 1184-1189
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Konferensbidrag (refereegranskat)abstract
- Students of an Internet based course in project management worked during a 20 week period in teams of 4-6 persons. The course consisted of Swedish students living in Sweden or abroad which made it impossible for many of the teams to have any face-to-face interaction. During the course the teams were assigned to a series of discussion questions and cases. The study, based on a survey of 287 students who participated in the course, examined their experience of teamwork and showed that many of the classical team development issues also evolve in a virtual team. Furthermore, the study showed that students considered their teamwork was efficient and that being able to communicate, discuss and share experiences was essential for developing a positive learning community.
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| 18. |
- Blomquist, Tomas, et al.
(författare)
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Development of virtual teams and learning communities
- 2006
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Ingår i: Collaborating virtually. - Punjagutta, India : Icfai University Press. - 8131403084 ; , s. 121-131
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Bokkapitel (refereegranskat)abstract
- Students of an Internet based course in project management worked during a 20 week period worked in teams of 4-6 persons. The course consisted of Swedish students living in Sweden or abroad, which made it impossible for many of the teams to have any face-to-face interaction. During the course, the teams were assigned a series of discussion questions and cases. The study, based on a survey of 287 students who participated in the course, examined their experience of teamwork and showed that many of the classical team development issues also evolve in a virtual team. Furthermore, the study showed that students considered their teamwork was efficient and that being able to communicate, discuss and share experiences was essential for developing a positive learning community.
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| 19. |
- Blomquist, Tomas, et al.
(författare)
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Project as practice : making project research matter
- 2006
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Ingår i: Proceedings of IRNOP VII project research conference. - Beijing : China Publishing House of Electronics Industry. - 712103252X ; , s. 540-549
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Konferensbidrag (refereegranskat)abstract
- Project theory is not only an immature field of research, it is insubstantial when it comes to understanding what is really going on in projects. This paper contributes to making project research matter to the academic as well as the practitioner through the theoretical development of a project-as-practice approach, aligned with an ongoing debate in social science research. We outline the framework of project-as-practice and argue that there are two major challenges to the researcher: the relevance challenge and the pattern challenge. We suggest how these challenges can be met and give some examples of earlier studies that have done so. The practice approach is not a substitute to present theorizing but rather a complement that brings substance. Finally, underlying notions of the practice approach are outlined in order to have a fruitful future development of a project-as-practice approach that makes project theory matter!
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| 20. |
- Brandin, Jan, et al.
(författare)
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Bio-propane from glycerol for biogas addition
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report, the technical and economical feasibility to produce higher alkanes from bio-glycerol has been investigated. The main purpose of producing this kind of chemicals would be to replace the fossil LPG used in upgraded biogas production. When producing biogas and exporting it to the natural gas grid, the Wobbe index and heating value does not match the existing natural gas. Therefore, the upgraded biogas that is put into the natural gas grid in Sweden today contains 8-10 vol-% of LPG. The experimental work performed in association to this report has shown that it is possible to produce propane from glycerol. However, the production of ethane from glycerol may be even more advantageous. The experimental work has included developing and testing catalysts for several intermediate reactions. The work was performed using different micro-scale reactors with a liquid feed rate of 18 g/h. The first reaction, independent on if propane or ethane is to be produced, is dehydration of glycerol to acrolein. This was showed during 60 h on an acidic catalyst with a yield of 90%. The production of propanol, the second intermediate to producing propane, was shown as well. Propanol was produced both using acrolein as the starting material as well as glycerol (combining the first and second step) with yields of 70-80% in the first case and 65-70% in the second case. The propanol produced was investigated for its dehydration to propene, with a yield of 70-75%. By using a proprietary, purposely developed catalyst the propene was hydrogenated to propane, with a yield of 85% from propanol. The formation of propane from glycerol was finally investigated, with an overall yield of 55%. The second part of the experimental work performed investigated the possibilities of decarbonylating acrolein to form ethane. This was made possible by the development of a proprietary catalyst which combines decarbonylation and water-gas shift functionality. By combining these two functionalities, no hydrogen have to be externally produced which is the case of the propane produced. The production of ethane from acrolein was shown with a yield of 75%, while starting from glycerol yielded 65-70% ethane using the purposely developed catalyst. However, in light of this there are still work to be performed with optimizing catalyst compositions and process conditions to further improve the process yield. The economic feasibility and the glycerol supply side of the proposed process have been investigated as well within the scope of the report. After an initial overview of the glycerol supply, it is apparent that at least the addition of alkanes to biogas can be saturated by glycerol for the Swedish market situation at the moment and for a foreseeable future. The current domestic glycerol production would sustain the upgraded biogas industry for quite some time, if necessary. However, from a cost standpoint a lower grade glycerol should perhaps be considered. In the cost aspect, three different configurations have been compared. The three alternatives are ethane production, propane production with internal hydrogen supply and propane production with external hydrogen supply. The results from the base case calculations can be viewed in table ES1. The base case calculations are based on carburating the upgraded biogas, before introducing it to the natural gas grid, from a 24 GWh biogas production facility. This means that the production units supply an acceptable Wobbe index of the final upgraded biogas. The annual cost in table ES1 is the yearly cost of carburating the gas at a 24 GWh biogas site. From the base case, it is obvious that there are differences in glycerol consumption depending on what alternative is chosen. There are also investment cost differences. To further investigate the volatility of the prices, a blend of Monte Carlo techniques were used to generate multiple data sets. The conclusions from the simulations were that the ethane producing facility has a stronger dependence on the feedstock; it is hence more sensitive to changes in the feedstock cost. It is however not as sensitive to changes in investment cost. If the production cost is compared to the cost of fossil LPG used today, the cost of the LPG is 0.43 kr/kWh. This does however not include the taxation and transporting the fuel. Adding the taxation alone will put an additional 0.25 kr/kWh on the cost, totalling 0.68 kr/kWh. This compares well with the calculated production cost of 0.78 kr/kWh for ethane and with the 50% percentile acquired from the Monte Carlo simulations of 0.94 kr/kWh.
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| 21. |
- Bredthauer, Andreas, 1977-
(författare)
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Tensionless Strings and Supersymmetric Sigma Models : Aspects of the Target Space Geometry
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, two aspects of string theory are discussed, tensionless strings and supersymmetric sigma models.The equivalent to a massless particle in string theory is a tensionless string. Even almost 30 years after it was first mentioned, it is still quite poorly understood. We discuss how tensionless strings give rise to exact solutions to supergravity and solve closed tensionless string theory in the ten dimensional maximally supersymmetric plane wave background, a contraction of AdS(5)xS(5) where tensionless strings are of great interest due to their proposed relation to higher spin gauge theory via the AdS/CFT correspondence.For a sigma model, the amount of supersymmetry on its worldsheet restricts the geometry of the target space. For N=(2,2) supersymmetry, for example, the target space has to be bi-hermitian. Recently, with generalized complex geometry, a new mathematical framework was developed that is especially suited to discuss the target space geometry of sigma models in a Hamiltonian formulation. Bi-hermitian geometry is so-called generalized Kähler geometry but the relation is involved. We discuss various amounts of supersymmetry in phase space and show that this relation can be established by considering the equivalence between the Hamilton and Lagrange formulation of the sigma model. In the study of generalized supersymmetric sigma models, we find objects that favor a geometrical interpretation beyond generalized complex geometry.
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| 22. |
- Brodnik, Andrej, et al.
(författare)
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An O(1) solution to the prefix sum problem on a specialized memory architecture
- 2006
-
Ingår i: PFourth IFIP International Conference on Theoretical Computer Science - TCS 2006. - New York : Encyclopedia of Global Archaeology/Springer Verlag. - 9780387346335 ; , s. 103-114
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Konferensbidrag (refereegranskat)abstract
- In this paper we study the Prefix Sum problem introduced by Fredman. We show that it is possible to perform both update and retrieval in O(1) time simultaneously under a memory model in which individual bits may be shared by several words. We also show that two variants (generalizations) of the problem can be solved optimally in Θ(lgN) time under the comparison based model of computation.
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| 23. |
- Bylesjö, Max, et al.
(författare)
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Integrated analysis of transcript, protein and metabolite data to study lignin biosynthesis in hybrid aspen
- 2009
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 8:1, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- Tree biotechnology will soon reach a mature state where it will influence the overall supply of fiber, energy and wood products. We are now ready to make the transition from identifying candidate genes, controlling important biological processes, to discovering the detailed molecular function of these genes on a broader, more holistic, systems biology level. In this paper, a strategy is outlined for informative data generation and integrated modeling of systematic changes in transcript, protein and metabolite profiles measured from hybrid aspen samples. The aim is to study characteristics of common changes in relation to genotype-specific perturbations affecting the lignin biosynthesis and growth. We show that a considerable part of the systematic effects in the system can be tracked across all platforms and that the approach has a high potential value in functional characterization of candidate genes.
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| 24. |
- Cederkäll, Joakim, et al.
(författare)
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Sub-Barrier Coulomb Excitation of ^110Sn and Its Implications for the ^100Sn Shell Closure
- 2007
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Ingår i: Physical Review Letters. - 1079-7114. ; 98:17, s. 172501-
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Tidskriftsartikel (refereegranskat)abstract
- The first excited 2+ state of the unstable isotope 110Sn has been studied in safe Coulomb excitation at 2.82 MeV/u using the MINIBALL array at the REX-ISOLDE post accelerator at CERN. This is the first measurement of the reduced transition probability of this state using this method for a neutron deficient Sn isotope. The strength of the approach lies in the excellent peak-to-background ratio that is achieved. The extracted reduced transition probability, B(E2:0+-->2+)=0.220±0.022e2b2, strengthens the observation of the evolution of the B(E2) values of neutron deficient Sn isotopes that was observed recently in intermediate-energy Coulomb excitation of 108Sn. It implies that the trend of these reduced transition probabilities in the even-even Sn isotopes is not symmetric with respect to the midshell mass number A=116 as 100Sn is approached.
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| 25. |
- Duan, Rui-Dong, et al.
(författare)
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Human meconium contains significant amounts of alkaline sphingomyelinase, neutral ceramidase, and sphingolipid metabolites.
- 2007
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Ingår i: Pediatric Research. - : Springer Science and Business Media LLC. - 1530-0447 .- 0031-3998. ; 61:1, s. 61-66
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal alkaline sphingomyelinase (Alk-SMase) and neutral ceramidase may catalyze the hydrolysis of endogenous sphin-gomyelin (SM) and milk SM in human-milk fed infants. The enzymes generate sphingolipid metabolites that may influence gut maturation. Alk-SMase also inactivates platelet-activating factor (PAF) that is involved in the pathogenesis of necrotizing enterocolitis (NEC). We examined whether the two enzymes are expressed in both preterm and term infants and analyzed Alk-SMase, neutral ceramidase, SM, and sphingolipid metabolites in meconium. Meconium was collected from 46 preterm (gestational ages 23-36 wk) and 38 term infants (gestational ages 37-42 wk) and analyzed for Alk-SMase using C-14-choline-labeled SM and for neutral ceramidase using C-14-octanoyl-sphingosine as substrates. Molecular species of SM, ceramide, and sphingosine were analyzed by high-performance liquid chromatography mass spectroscopy. Meconium contained significant levels of Alk-SMase and ceramidase at all gestational ages. It also contained 16-24 carbon molecular species of SM, palmitoyl-and stearoyl-sphingosine, and sphingosine. There were positive correlations between levels of SM and ceramide and between ceramide and sphingosine levels. In conclusion, Alk-SMase and ceramidase are expressed in the gut of both preterm and term newborn infants and may generate bioactive sphingolipid messengers.
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