| 1. |
- Aldaeus, Fredrik, et al.
(författare)
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Towards a cellulose-based society : current market and consumer trends
- 2017
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Ingår i: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017. - Stockholm : RISE Bioekonomi. - 9789186018207 ; , s. 1-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- It has been proposed that the future of the forest industry will involve the traditional value chains combined with the needs and demands of a bio-based economy. A global consumer survey was undertaken, together with interviews and workshops with various representatives through the bio-economy. Sources also included in-depth literature studies and research reviews. Based on this input, several current trends have been identified that will affect the route towards a cellulose-based society. These trends describe the effects of urbanization, consumer behaviour, new business models, material recycling, open innovation and the necessity for early demonstration of new research. Four different but equally plausible scenarios have been identified describing the society and the role of cellulose in 2030, highlighting the role of the wood-based biorefinery.
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| 2. |
- Aldaeus, Fredrik, et al.
(författare)
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Towards a cellulose-based society : current trends, future scenarios, and the role of the wood biorefinery
- 2016
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Ingår i: Proceedings of the 14th European workshop on lignocellulosics and pulp. - 9791090188020 ; , s. 125-127
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There is a great need to maintain research for a future in which the traditional value chains of the forest industry are combined with the needs and demands of a bio-based economy. In such a future, the pulp mill biorefinery will be a crucial node. In order to map the transformation from a fossil-based society to a cellulose-based society, a global consumer survey has been made. In addition, interviews and workshops with various players throughout the bio-economy field have been accomplished. Several current trends that affect the road to a cellulose-based society have been identified. These trends are describing the effects of urbanization, consumer behaviour, new business models, material recycling, open innovation, and the need for early demonstration of new research. The trends have been combined with uncertainties into a number of plausible scenarios describing the society and the role of cellulose in the year 2030.
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| 3. |
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| 4. |
- Hassellöv, Ida-Maja, 1974, et al.
(författare)
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Miljörisker sjunkna vrak II. Undersökningsmetoder och miljöaspekter
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- During 2015 the Swedish Maritime Administration continued the second phase of thegovernmental task Environmental risks from sunken wrecks which first report was finalized2014-10-31 (Dnr: 1399-14-01942-6).The main conclusions from the 2014 report remain; for future handling of potentially pollutingshipwrecks it is recommended that the Swedish Agency for Water and Marine Management isgiven a coordinating responsibility in close cooperation with other competent nationalauthorities, such as Swedish Maritime Administration, Swedish Coastguard, Swedish NationalMaritime Museums, the Geological Survey of Sweden, SMHI, Swedish EPA, and SwedishCivil Contingencies Agency. Through coordination of wreck related operations and activitieswithin the concerned competent authorities’ ordinary areas of responsibility, resourceefficiency is improved. The estimated extra cost for implementation of a national strategy forhandling of the wrecks are estimated to be 10-15 MSEK which should be allocated to thecompetent authorities by the Swedish Agency for Water and Marine Management.The conclusions from 2014 was reinforced during 2015, e.g. through the validation of the riskassessment model VRAKA, which is now available in a first operative version. Additionalecotoxicological experiments on the development of tolerance against PAHs in meiofauna andmicroorganism communities were conducted in a field study in Brofjorden. The mainconclusions from this work is that comprehensive analyzes of PAHs should include alkylatedPAHs, and that exposure to PAHs over time can lead to tolerance development in ammoniumoxidizing bacteria, at the expense of their ability to perform the essential ecosystem servicenitrification.Continued measurements of the bottom currents were made at the wrecks Villon and Skytteren,and at the dumping area west of Måseskär. Measurement series yielded important informationon how measuring equipment at the wreck can be deployed in an optimized way in futuremonitoring program; to calculate the possible spreading of pollution from a wreck, currentmeasurements should be performed upstream from the wreck site, while sensors for thedetection of, for example, oil should be put into the turbulence downstream of the wreck.The current measurement instruments (RDCP) deployed at the Måseskär dump site was trawledup after only three weeks of measurements, but still gave valuable information on the extensivebottom trawling that resuspend (stir up) sediments. Earlier geochemical surveys have shownsignificantly elevated arsenic concentrations in the area and sediment resuspension greatlyincreased the risk for spread of any contaminants in the area. Trawling is not prohibited in thearea, and the current lack of knowledge regarding potential effects on human health whenconsuming seafood from dump areas calls for reflection upon the suitability of trawling in thearea.In addition to the current measurements Swedish Maritime Administration and the SwedishNavy conducted hydrographic survey with multibeam and side scan sonar and ROVinvestigation of the wrecks in the dumping area at Måseskär. 28 wrecks were found, and ROVinvestigation showed cargo holds with dumped torpedoes or mines and other containers in some SjöfartsverketDnr: 1399-14-01942-156of the wrecks. There is some discrepancy between the previously measured elevated arsenicconcentrations in the Måseskär area and recently presented data from historical archives thatdoes not support the theory that chemical weapons were dumped in the area. However, there isa very good correlation between the dominant current direction in the area, and the highestmeasured arsenic concentrations in the area downstream of the wrecks, suggesting some formof arsenic source in the area.
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| 5. |
- Amir Heidari, Payam, 1989, et al.
(författare)
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A state-of-the-art model for spatial and stochastic oil spill risk assessment: A case study of oil spill from a shipwreck
- 2019
-
Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 126, s. 309-320
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Tidskriftsartikel (refereegranskat)abstract
- Oil spills are serious environmental issues that potentially can cause adverse effects on marine ecosystems. In some marine areas, like the Baltic Sea, there is a large number of wrecks from the first half of the 20th century, and recent monitoring and field work have revealed release of oil from some of these wrecks. The risk posed by a wreck is governed by its condition, hazardous substances contained in the wreck and the state of the surrounding environment. Therefore, there is a need for a common standard method for estimating the risks associated with different wrecks. In this work a state-of-the-art model is presented for spatial and stochastic risk assessment of oil spills from wrecks, enabling a structured approach to include the complex factors affecting the risk values. A unique feature of this model is its specific focus on uncertainty, facilitating probabilistic calculation of the total risk as the integral expected sum of many possible consequences. A case study is performed in Kattegat at the entrance region to the Baltic Sea to map the risk from a wreck near Sweden. The developed model can be used for oil spill risk assessment in the marine environment all over the world.
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| 6. |
- Bjureland, William
(författare)
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On reliability-based design of rock tunnel support
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tunneling involves large uncertainties. Since 2009, design of rock tunnels in European countries should be performed in accordance with the Eurocodes. The main principle in the Eurocodes is that it must be shown in all design situations that no relevant limit state is exceeded. This can be achieved with a number of different methods, where the most common one is design by calculation. To account for uncertainties in design, the Eurocode states that design by calculation should primarily be performed using limit state design methods, i.e. the partial factor method or reliability-based methods. The basic principle of the former is that it shall be assured that a structure’s resisting capacity is larger than the load acting on the structure, with high enough probability. Even if this might seem straightforward, the practical application of limit state design to rock tunnel support has only been studied to a limited extent.The aim of this licentiate thesis is to provide a review of the practical applicability of using reliability-based methods and the partial factor method in design of rock tunnel support. The review and the following discussion are based on findings from the cases studied in the appended papers. The discussion focuses on the challenges of applying fixed partial factors, as suggested by Eurocode, in design of rock tunnel support and some of the practical difficulties the engineer is faced with when applying reliability-based methods to design rock tunnel support.The main conclusions are that the partial factor method (as defined in Eurocode) is not suitable to use in design of rock tunnel support, but that reliability-based methods have the potential to account for uncertainties present in design, especially when used within the framework of the observational method. However, gathering of data for statistical quantification of input variables along with clarification of the necessary reliability levels and definition of “failure” are needed.
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| 7. |
- Cancer, Matko, et al.
(författare)
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BET and Aurora Kinase A inhibitors synergize against MYCN-positive human glioblastoma cells
- 2019
-
Ingår i: Cell Death and Disease. - : NATURE PUBLISHING GROUP. - 2041-4889. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults. Patients usually undergo surgery followed by aggressive radio- and chemotherapy with the alkylating agent temozolomide (TMZ). Still, median survival is only 12-15 months after diagnosis. Many human cancers including GBMs demonstrate addiction to MYC transcription factor signaling and can become susceptible to inhibition of MYC downstream genes. JQ1 is an effective inhibitor of BET Bromodomains, a class of epigenetic readers regulating expression of downstream MYC targets. Here, we show that BET inhibition decreases viability of patient-derived GBM cell lines. We propose a distinct expression signature of MYCN-elevated GBM cells that correlates with significant sensitivity to BET inhibition. In tumors showing JQ1 sensitivity, we found enrichment of pathways regulating cell cycle, DNA damage response and repair. As DNA repair leads to acquired chemoresistance to TMZ, JQ1 treatment in combination with TMZ synergistically inhibited proliferation of MYCN-elevated cells. Bioinformatic analyses further showed that the expression of MYCN correlates with Aurora Kinase A levels and Aurora Kinase inhibitors indeed showed synergistic efficacy in combination with BET inhibition. Collectively, our data suggest that BET inhibitors could potentiate the efficacy of either TMZ or Aurora Kinase inhibitors in GBM treatment.
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| 8. |
- Čančer, Matko, et al.
(författare)
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Humanized Stem Cell Models of Pediatric Medulloblastoma Reveal an Oct4/mTOR Axis that Promotes Malignancy
- 2019
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Ingår i: Cell Stem Cell. - : CELL PRESS. - 1934-5909 .- 1875-9777. ; 25:6, s. 855-870
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Tidskriftsartikel (refereegranskat)abstract
- Medulloblastoma (MB), the most frequent malignant childhood brain tumor, can arise from cellular malfunctions during hindbrain development. Here we generate humanized models for Sonic Hedgehog (SHH)-subgroup MB via MYCN overexpression in primary human hindbrain-derived neuroepithelial stem (hbNES) cells or iPSC-derived NES cells, which display a range of aggressive phenotypes upon xenografting. iPSC-derived NES tumors develop quickly with leptomeningeal dissemination, whereas hbNES-derived cells exhibit delayed tumor formation with less dissemination. Methylation and expression profiling show that tumors from both origins recapitulate hallmarks of infant SHH MB and reveal that mTOR activation, as a result of increased Oct4, promotes aggressiveness of human SHH tumors. Targeting mTOR decreases cell viability and prolongs survival, showing the utility of these varied models for dissecting mechanisms mediating tumor aggression and demonstrating the value of humanized models for a better understanding of pediatric cancers.
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| 9. |
- Juvrud, Joshua, et al.
(författare)
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The Immersive Virtual Reality Lab : Possibilities for Remote Experimental Manipulations of Autonomic Activity on a Large Scale
- 2018
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Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for large-scale remote data collection in a controlled environment, and the in-home availability of virtual reality (VR) and the commercial availability of eye tracking for VR present unique and exciting opportunities for researchers. We propose and provide a proof-of-concept assessment of a robust system for large-scale in-home testing using consumer products that combines psychophysiological measures and VR, here referred to as a Virtual Lab. For the first time, this method is validated by correlating autonomic responses, skin conductance response (SCR), and pupillary dilation, in response to a spider, a beetle, and a ball using commercially available VR. Participants demonstrated greater SCR and pupillary responses to the spider, and the effect was dependent on the proximity of the stimuli to the participant, with a stronger response when the spider was close to the virtual self. We replicated these effects across two experiments and in separate physical room contexts to mimic variability in home environment. Together, these findings demonstrate the utility of pupil dilation as a marker of autonomic arousal and the feasibility to assess this in commercially available VR hardware and support a robust Virtual Lab tool for massive remote testing.
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| 10. |
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| 11. |
- Landquist, Hanna, 1984, et al.
(författare)
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Expert elicitation for deriving input data for probabilistic risk assessment of shipwrecks
- 2017
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X .- 1879-3363. ; 125:1-2, s. 399-415
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Tidskriftsartikel (refereegranskat)abstract
- The necessity of having a process in place for adequate risk assessment of shipwrecks that pose a threat to the marine environment is today internationally acknowledged. However, retrieving the desired data for such a risk assessment can prove challenging. One means of addressing this problem is to make use of experts' knowledge and experience. The purpose of this paper is therefore to present and analyse data for risk assessment of shipwrecks derived by expert elicitation. The main outcome is the experts' estimations of (i) the generic probability of an opening in a shipwreck due to the occurrence of a number of activities and (ii) estimations of the degree to which site-specific and wreck-specific indicators affect the probability of opening. Results show that the derived information is applicable in probabilistic shipwreck risk assessment and that the VRAKA framework now contains needed information for integrating generic and site-specific information using Bayesian updating.
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| 12. |
- Landquist, Hanna, 1984, et al.
(författare)
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SWERA – Delivery 2.2
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Lindberg, Siv M, et al.
(författare)
-
Tactile and instrumental characterization of tissue products
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The feeling of softness and smoothness of paper tissue products is an important performance factor in the market place. In a series of panel tests, the relationship between instrumental measurements and perceived softness and smoothness was investigated. Samples of tissue base paper – napkin and toilet paper – were evaluated for surface roughness. The samples were placed on a hard, smooth glass substrate and the respondents used one finger to stroke along the sample surface. Instrumental measurement and characterization were performed using differentinstruments: Emtec TSA and Lena Softness Tester. The results divide the base paper material into product groups, but general mathematical relationships could be found between the test panel and the measurements when normalized in different ways. Measurements using the Lena produced the best correlation with the panel ratings because its principle resembled the method of the test panel most closely. However, a general relationship usingmaterial properties was shown to produce as good an estimator for the surface roughness as the results obtained with the Lena. This relationship consisted of the ratio between the plasticity and the elasticity of the tissue paper (in-plane properties), normalized for thickness. This suggests that those three material properties are fundamental to the perception of surface roughness as evaluated in this study. Using a trained haptic panel to evaluate test samples of similar grammage with variations in furnish and machine operation settings generated a good correlation to the TSA measurement (r=0.9). The panel was more susceptible to variation in furnish than variation in peak pressure, and this was particularly evident for samples evaluated on the Yankee side.
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| 14. |
- Lucisano, Marco, et al.
(författare)
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Stratified forming as a tool for resource efficient papermaking
- 2015
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Ingår i: Paper Conference and Trade Show (PaperCon 2015). - : TAPPI Press. - 9781510818873 ; , s. 767-785
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Konferensbidrag (refereegranskat)abstract
- Pilot-scale demonstration of stratified forming with innovative design of vane technology. Stratified dosage of fillers tested for: •SC-paper •Fine paper Dosage of filler and retention aid through the liquid layers gives a wider window of operation (retention-formation). Filler content can be increased with no adverse effects on strength and structure.
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| 15. |
- Mattsson, C. Mikael, et al.
(författare)
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Träna för en svensk klassiker och andra långlopp
- 2015
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Bok (populärvet., debatt m.m.)abstract
- Förbered dig rätt inför långlopp. Att under ett år genomföra Vätternrundan, Vansbrosimningen, Lidingöloppet och Engelbrektsloppet/Vasaloppet, är ett av de mest populära sätten att skörda frukten av sin träning och nå sitt mål. För att lyckas krävs goda förberedelser, och ju bättre förberedd du är desto mer positiv blir upplevelsen. Innehållet i denna bok är en fördjupning av samlad kunskap och erfarenhet inom simning, cykel, löpning, längdskidåkning och triathlon samt hur man på bästa sätt kombinerar de olika idrotterna – deras olika moment – i träning och tävling. Här hittar du också kapitel om träningslära, idrottsnutrition, mental träning, förebyggande av idrottsskador och träningsplanering för att öka förståelsen av vad som påverkar en idrottsprestation.Extramaterial på webbplatsen: För att kunna erbjuda mer än vad som ryms i en bok, har vi också skapat en webbplats. Med hjälp av koden som följer med i boken kan du registrera dig för att ta del av fördjupande texter, träningsprogram och kostupplägg, övningar och intressanta länkar.(Text från förlaget)
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| 16. |
- Meibohm, J., et al.
(författare)
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Angular velocity of a sphere in a simple shear at small Reynolds number
- 2016
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Ingår i: Physical Review Fluids. - : university of teheran. - 2469-990X. ; 1:8
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the angular velocity of a small neutrally buoyant spheroid log rolling in a simple shear. When the effect of fluid inertia is negligible the angular velocity. equals half the fluid vorticity. We compute by singular perturbation theory how weak fluid inertia reduces the angular velocity in an unbounded shear, and how this reduction depends upon the shape of the spheroid (on its aspect ratio). In addition we determine the angular velocity by direct numerical simulations. The results are in excellent agreement with the theory at small but not too small values of the shear Reynolds number Res, for all aspect ratios considered. For the special case of a sphere we find omega/s = -1/2 + 0.0540 Re-s(3/2) where s is the shear rate. The O( Re-s(3/2)) correction differs from that derived by Lin et al. who obtained a numerical coefficient roughly three times larger.
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| 17. |
- Meibohm, Jan, et al.
(författare)
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Angular velocity of a spheroid log rolling in a simple shear at small Reynolds number
- 2016
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Ingår i: Physical Review Fluids. - 2469-990X. ; 1:8
-
Tidskriftsartikel (refereegranskat)abstract
- We analyse the angular velocity of a small neutrally buoyant spheroid log rolling in a simple shear. When the effect of fluid inertia is negligible the angular velocity ω equals half the fluid vorticity. We compute by singular perturbation theory how weak fluid inertia reduces the angular velocity in an unbounded shear, and how this reduction depends upon the shape of the spheroid (on its aspect ratio). In addition we determine the angular velocity by direct numerical simulations. The results are in excellent agreement with the theory at small but not too small values of the shear Reynolds number, for all aspect ratios considered. For the special case of a sphere we find ω/s=−1/2+0.0540 Re_s^3/2 where s is the shear rate, and Re_s is the shear Reynolds number. This result differs from that derived by Lin et al. [J. Fluid Mech. 44 (1970) 1] who obtained a numerical coefficient roughly three times larger.
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| 18. |
- Mohseni, Simin, et al.
(författare)
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Longitudinal study of neuropathy, microangiopathy, and autophagy in sural nerve : Implications for diabetic neuropathy
- 2017
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Ingår i: Brain and Behavior. - : Wiley Online Library. - 2162-3279. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- The progression and pathophysiology of neuropathy in impaired glucose tolerance (IGT) and type 2 diabetes (T2DM) is poorly understood, especially in relation to autophagy. This study was designed to assess whether the presence of autophagy-related structures was associated with sural nerve fiber pathology, and to investigate if endoneurial capillary pathology could predict the development of T2DM and neuropathy. Sural nerve physiology and ultrastructural morphology were studied at baseline and 11 years later in subjects with normal glucose tolerance (NGT), IGT, and T2DM. Subjects with T2DM had significantly lower sural nerve amplitude compared to subjects with NGT and IGT at baseline. Myelinated and unmyelinated fiber, endoneurial capillary morphology, and the presence and distribution of autophagy structures were comparable between groups at baseline, except for a smaller myelinated axon diameter in subjects with T2DM and IGT compared to NGT. The baseline values of the subjects with NGT and IGT who converted to T2DM 11 years later demonstrated healthy smaller endoneurial capillary and higher g-ratio versus subjects who remained NGT. At follow-up, T2DM showed a reduction in nerve conduction, amplitude, myelinated fiber density, unmyelinated axon diameter, and autophagy structures in myelinated axons. Endothelial cell area and total diffusion barrier was increased versus baseline. We conclude that small healthy endoneurial capillary may presage the development of T2DM and neuropathy. Autophagy occurs in human sural nerves and can be affected by T2DM. Further studies are warranted to understand the role of autophagy in diabetic neuropathy.
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| 19. |
- Rahmanto, Aldwin Suryo, et al.
(författare)
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FBW7 suppression leads to SOX9 stabilization and increased malignancy in medulloblastoma
- 2016
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Ingår i: EMBO Journal. - : EMBO. - 0261-4189 .- 1460-2075. ; 35:20, s. 2192-2212
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Tidskriftsartikel (refereegranskat)abstract
- SOX9 is a master transcription factor that regulates development and stem cell programs. However, its potential oncogenic activity and regulatory mechanisms that control SOX9 protein stability are poorly understood. Here, we show that SOX9 is a substrate of FBW7, a tumor suppressor, and a SCF (SKP1/CUL1/F-box)-type ubiquitin ligase. FBW7 recognizes a conserved degron surrounding threonine 236 (T236) in SOX9 that is phosphorylated by GSK3 kinase and consequently degraded by SCFFBW7 alpha. Failure to degrade SOX9 promotes migration, metastasis, and treatment resistance in medulloblastoma, one of the most common childhood brain tumors. FBW7 is either mutated or downregulated in medulloblastoma, and in cases where FBW7 mRNA levels are low, SOX9 protein is significantly elevated and this phenotype is associated with metastasis at diagnosis and poor patient outcome. Transcriptional profiling of medulloblastoma cells expressing a degradation-resistant SOX9 mutant reveals activation of pro-metastatic genes and genes linked to cisplatin resistance. Finally, we show that pharmacological inhibition of PI3K/AKT/mTOR pathway activity destabilizes SOX9 in a GSK3/FBW7-dependent manner, rendering medulloblastoma cells sensitive to cytostatic treatment.
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| 20. |
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| 21. |
- Reddy, Vijeth Venkataram, 1990-, et al.
(författare)
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Lead free Brass : Topography Characterization
- 2016
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Konferensbidrag (refereegranskat)abstract
- The negative effects of lead on human health and the recycling problems of copper alloys with lead content has led to the increase in concern for reducing/eliminating the use of lead in brass and other copper alloys. Many materials are considered to replace lead in brass; silicon is one such alternative. The real challenge prevails in sustainable manufacturing of lead free brass, to maintain control of the surface integrity when substituting the lead content in the brass with silicon. The investigation includes defined areal surface parameters measured on the turned samples of lead- and lead free brass using an optical coherence scanning interferometer, CSI.This paper deals with the study of surface topography of turned samples of lead and lead free brass. It is important to study the topographical characteristics of the brass samples which are the intermediate link between the manufacturing process variables and the functional behaviour of the surface. To numerically evaluate the sample’s surface topography and to validate the measurements for a significant study, a general statistical methodology is implemented. The results suggest that the surface roughness is higher in lead brass compared to lead free brass and tool coatings have significant influence on the hybrid (Sdr & Sdq) parameters in the surface topography of brass samples.
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| 22. |
- Reddy, Vijeth Venkataram, 1990-, et al.
(författare)
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Surface topography characterization of brass alloys : lead brass (CuZn39Pb3) and lead free brass (CuZn21Si3P)
- 2017
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : Institute of Physics Publishing (IOPP). - 2051-672X. ; 5:2
-
Tidskriftsartikel (refereegranskat)abstract
- Manufactured surfaces usually consist of topographical features which include both those put forth by the manufacturing process, and micro-features caused by disturbances during this process. Surface characterization basically involves study of these features which influence the functionality of the surface. This article focuses on characterization of the surface topography of machined lead brass and lead free brass. The adverse effect of lead on human health and the environment has led the manufacturing sector to focus on sustainable manufacturing of lead free brass, as well as how to maintain control of the surface integrity when substituting the lead content in the brass with silicon. The investigation includes defined areal surface parameters measured on the turned samples of lead- and lead free brass using an optical coherence scanning interferometer, CSI. This paper deals with the study of surface topography of turned samples of lead-and lead free brass. It is important to study the topographical characteristics of the brass samples which are the intermediate link between the manufacturing process variables and the functional behaviour of the surface. To numerically evaluate the sample's surface topography and to validate the measurements for a significant study, a general statistical methodology is implemented. The results indicate higher surface roughness in turned samples of lead brass compared to lead free brass. © 2017 IOP Publishing Ltd
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| 23. |
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| 24. |
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| 25. |
- Rosén, Jörgen, 1978-
(författare)
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Innate and Conditioned Fear : Investigating Responses to Threat using Psychophysiology, Functional Magnetic Resonance Imaging, and Twin Methodology
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Evolution has shaped systems in the human brain to respond to danger. Some of these systems are innate or hard-wired, while others are learned throughout the entire life span. One commonly studied type of learned threat, conditioned fear, is acquired from experiencing aversive consequences. When considering innate threat, processing imminent and social threat may be especially relevant for understanding the neural circuitry of human fear. Imminent fear refers to experiencing proximal encounters whereas social fear refers to exposure to an unknown conspecific. Investigating whether different brain systems process innate and conditioned threat could provide us with knowledge on how defensive systems interact and inform on development and treatment of fear-related disorders. The first aim of this thesis was to investigate whether different brain systems process innate and conditioned threat. The second aim was to investigate if neural functions supporting imminent and social threat are heritable. In Study I, skin conductance responses (SCR) to social, imminent and conditioned threat displayed in immersive virtual-reality were compared. The results showed that social threat modulated imminent threat, but neither imminent nor social threat modulated conditioned threat, indicating that distinct processes regulate imminent and social threat on one end and conditioned threat on the other. Study II compared SCR to imminent and conditioned threat displayed either in an immersive virtual-reality head-mounted display or a regular computer monitor. The findings indicated that displaying stimuli in an immersive virtual-reality head-mounted display enhanced imminent threat responses as compared to displaying them on a regular computer monitor, suggesting a modulation of SCR by display type. Conditioned SCR was similar across displays. The conclusion of the study was that imminent threat and conditioned threat are different processes as it was possible to modulate one without affecting the other. Study III was a twin study comparing the genetic influence on neural responses to imminent and social threat using functional magnetic resonance imaging (fMRI) and SCR. The results demonstrated strong genetic influence on responses in the lateral occipital cortex and the fusiform cortex to social threat whereas genetic influence on imminent threat was strong in early visual areas and occipito-parietal areas. In summary, innate and conditioned fear may depend on separate processes in the brain. Innate threat activates early visual areas, indicating a role for these areas in threat processing. Genetic influences on fMRI responses to social and imminent threat suggests that separate pathways may have evolved to process these threats.
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| 26. |
- Rosén, Jörgen, et al.
(författare)
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Social, proximal and conditioned threat
- 2017
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 142, part B, s. 236-243
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Tidskriftsartikel (refereegranskat)abstract
- Responding to threats in the environment is crucial for survival. Certain types of threat produce defensive responses without necessitating previous experience and are considered innate, whereas other threats are learned by experiencing aversive consequences. Two important innate threats are whether an encountered stimulus is a member of the same species (social threat) and whether a stimulus suddenly appears proximal to the body (proximal threat). These threats are manifested early in human development and robustly elicit defensive responses. Learned threat, on the other hand, enables adaptation to threats in the environment throughout the life span. A well-studied form of learned threat is fear conditioning, during which a neutral stimulus acquires the ability to eliciting defensive responses through pairings with an aversive stimulus. If innate threats can facilitate fear conditioning, and whether different types of innate threats can enhance each other, is largely unknown. We developed an immersive virtual reality paradigm to test how innate social and proximal threats are related to each other and how they influence conditioned fear. Skin conductance responses were used to index the autonomic component of the defensive response. We found that social threat modulates proximal threat, but that neither proximal nor social threat modulates conditioned fear. Our results suggest that distinct processes regulate autonomic activity in response to proximal and social threat on the one hand, and conditioned fear on the other.
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| 27. |
- Rosén, Jörgen, et al.
(författare)
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The effect of immersive virtual reality on proximal and conditioned threat
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Virtual reality lets the user be immersed in a 3-dimensional environment, which can enhance certain emotional responses to stimuli relative to experiencing them on a flat computer screen. We here tested whether displaying two different types of threats in immersive virtual reality enhanced threat related autonomic responses measured by skin conductance responses (SCRs). We studied innate and learned threat responses because these types of threats have been shown to depend on different neural circuits in animals. Therefore, it is possible that immersive virtual reality may modulate one of these threats but not the other. Innate threat responses were provoked by the sudden appearance of characters at proximal egocentric distance, which were compared to the sudden appearance of distant characters (proximal threat). Learned threat responses were studied by conditioning two of the characters to an electric shock (conditioned threat) and contrasting SCRs to these characters with SCRs to two other characters that were never paired with shock. We found that displaying stimuli in immersive virtual reality enhanced proximal threat responses but not conditioned threat responses. Findings show that immersive virtual reality can enhance an innate type of threat responses without affecting a learned threat response, suggesting that separate neural pathways serve these threat responses.
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| 28. |
- Rosén, Tomas, 1985-
(författare)
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Angular dynamics of non-spherical particles in linear flows related to production of biobased materials
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dispersed particle flows are encountered in many biological, geophysical but also in industrial situations, e.g. during processing of materials. In these flows, the particles usually are non-spherical and their angular dynamics play a crucial role for the final material properties. Generally, the angular dynamics of a particle is dependent on the local flow in the frame-of-reference of this particle. In this frame, the surrounding flow can be linearized and the linear velocity gradient will determine how the particle rotates. In this thesis, the main objective is to improve the fundamental knowledge of the angular dynamics of non-spherical particles related to two specific biobased material processes.Firstly, the flow of suspended cellulose fibers in a papermaking process is used as a motivation. In this process, strong shear rates close to walls and the size of the fibers motivates the study of inertial effects on a single particle in a simple shear flow. Through direct numerical simulations combined with a global stability analysis, this flow problem is approached and all stable rotational states are found for spheroidal particles with aspect ratios ranging from moderately slender fibers to thin disc-shaped particles.The second material process of interest is the production of strong cellulose filaments produced through hydrodynamic alignment and assembly of cellulose nanofibrils (CNF). The flow in the preparation process and the small size of the particles motivates the study of alignment and rotary diffusion of CNF in a strain flow. However, since the particles are smaller than the wavelength of visible light, the dynamics of CNF is not easily captured with standard optical techniques. With a new flow-stop experiment, rotary diffusion of CNF is measured using Polarized optical microscopy. This process is found to be quite complicated, where short-range interactions between fibrils seem to play an important role. New time-resolved X-ray characterization techniques were used to target the underlying mechanisms, but are found to be limited by the strong degradation of CNF due to the radiation.Although the results in this thesis have limited direct applicability, they provide important fundamental stepping stones towards the possibility to control fiber orientation in flows and can potentially lead to new tailor-made materials assembled from a nano-scale.
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| 29. |
- Rosen, Tomas, et al.
(författare)
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Numerical analysis of the angular motion of a neutrally buoyant spheroid in shear flow at small Reynolds numbers
- 2015
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - : American Physical Society. - 1539-3755 .- 1550-2376. ; 92:6
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Tidskriftsartikel (refereegranskat)abstract
- We numerically analyze the rotation of a neutrally buoyant spheroid in a shear flow at small shear Reynolds number. Using direct numerical stability analysis of the coupled nonlinear particle-flow problem, we compute the linear stability of the log-rolling orbit at small shear Reynolds number Re-a. As Re-a -> 0 and as the box size of the system tends to infinity, we find good agreement between the numerical results and earlier analytical predictions valid to linear order in Re-a for the case of an unbounded shear. The numerical stability analysis indicates that there are substantial finite-size corrections to the analytical results obtained for the unbounded system. We also compare the analytical results to results of lattice Boltzmann simulations to analyze the stability of the tumbling orbit at shear Reynolds numbers of order unity. Theory for an unbounded system at infinitesimal shear Reynolds number predicts a bifurcation of the tumbling orbit at aspect ratio lambda(c) approximate to 0.137 below which tumbling is stable (as well as log rolling). The simulation results show a bifurcation line in the lambda-Re-a plane that reaches lambda approximate to 0.1275 at the smallest shear Reynolds number (Re-a = 1) at which we could simulate with the lattice Boltzmann code, in qualitative agreement with the analytical results.
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| 30. |
- Rosén, Tomas, 1985-, et al.
(författare)
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Orientational dynamics of a triaxial ellipsoid in simple shear flow : Influence of inertia
- 2017
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Ingår i: Physical review. E. - : AMER PHYSICAL SOC. - 2470-0045 .- 2470-0053. ; 96:1
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Tidskriftsartikel (refereegranskat)abstract
- The motion of a single ellipsoidal particle in simple shear flow can provide valuable insights toward understanding suspension flows with nonspherical particles. Previously, extensive studies have been performed on the ellipsoidal particle with rotational symmetry, a so-called spheroid. The nearly prolate ellipsoid (one major and two minor axes of almost equal size) is known to perform quasiperiodic or even chaotic orbits in the absence of inertia. With small particle inertia, the particle is also known to drift toward this irregular motion. However, it is not previously understood what effects from fluid inertia could be, which is of highest importance for particles close to neutral buoyancy. Here, we find that fluid inertia is acting strongly to suppress the chaotic motion and only very weak fluid inertia is sufficient to stabilize a rotation around themiddle axis. Themechanism responsible for this transition is believed to be centrifugal forces acting on fluid, which is dragged along with the rotational motion of the particle. With moderate fluid inertia, it is found that nearly prolate triaxial particles behave similarly to the perfectly spheroidal particles. Finally, we also are able to provide predictions about the stable rotational states for the general triaxial ellipsoid in simple shear with weak inertia.
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| 31. |
- Rosén, Tomas, et al.
(författare)
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Quantitative analysis of the angular dynamics of a single spheroid in simple shear flow at moderate Reynolds numbers
- 2016
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Ingår i: Physical Review Fluids. - : American Institute of Physics (AIP). - 2469-990X. ; 1:4, s. 044201-1-044201-21
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Tidskriftsartikel (refereegranskat)abstract
- A spheroidal particle in simple shear flow shows surprisingly complicated angular dynamics; caused by effects of fluid inertia (characterized by the particle Reynolds number Rep) and particle inertia (characterized by the Stokes number St). Understanding this behavior can provide important fundamental knowledge of suspension flows with spheroidal particles. Up to now only qualitative analysis has been available at moderate Rep. Rigorous analytical methods apply only to very small Rep and numerical results lack accuracy due to the difficulty in treating the moving boundary of the particle. Here we show that the dynamics of the rotational motion of a prolate spheroidal particle in a linear shear flow can be quantitatively analyzed through the eigenvalues of the log-rolling particle (particle aligned with vorticity). This analysis provides an accurate description of stable rotational states in terms of Rep,St, and particle aspect ratio (rp). Furthermore we find that the effect on the orientational dynamics from fluid inertia can be modeled with a Duffing-Van der Pol oscillator. This opens up the possibility of developing a reduced-order model that takes into account effects from both fluid and particle inertia.
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| 32. |
- Rosén, Tomas, et al.
(författare)
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Three-Dimensional Orientation of Nanofibrils in Axially Symmetric Systems Using Small-Angle X-ray Scattering
- 2018
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 122:12, s. 6889-6899
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Tidskriftsartikel (refereegranskat)abstract
- The increased availability and brilliance of new X-ray facilities have in the recent years opened up the possibility to characterize the alignment of dispersed anisotropic nanoparticles in various microfluidic applications, from hydrodynamic self-assemblies to flows in complex geometries. In such applications, it is vital to study the alignment of the nanoparticles in the flow, as this in turn affects the final properties of the self-assembled superstructures or those of the flow itself. Small-angle X-ray scattering (SAXS) is a well-suited characterization technique for this but typically provides the alignment in a projected plane perpendicular to the beam direction. In this work, we demonstrate a simple method to reconstruct the full three-dimensional orientation distribution function from a SAXS experiment through the assumption that the azimuthal angle of the nanoparticles around the flow direction is distributed uniformly, an assumption that is valid for a large range of nanoparticle flow processes. For demonstration purposes, the experimental results from previous works on hydrodynamic self-assembly of cellulose nanofibrils (CNFs) into filaments have been revised, resulting in a small correction to the presented order parameters. The results are then directly compared with simple numerical models to describe the increased alignment of CNFs both in the flowing system and during the drying of the filament. The proposed reconstruction method will allow for further improvements of theoretical or numerical simulations and consequently open up new possibilities for optimizing assembly processes, which include flow alignment of elongated nanoparticles.
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| 33. |
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| 34. |
- Thomas, Richard D., et al.
(författare)
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DESIREE : Physics with cold stored ion beams
- 2015
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Ingår i: DR2013. - : EDP Sciences. ; 84, s. 01004-01004
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Konferensbidrag (refereegranskat)abstract
- Here we will briefly describe the commissioning of the Double ElectroStatic Ion Ring ExpEriment (DESIREE) facility at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate rings and then merged over a common straight section. This apparatus allows for studies of interactions between cations and anions at very low and well-defined centre-of-mass energies (down to a few meV) and at very low internal temperatures (down to a few K).
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| 35. |
- Webb, Charlotta, et al.
(författare)
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Celiac disease can be predicted by high levels of anti-tissue transglutaminase antibodies in population-based screening
- 2015
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Ingår i: Journal of Pediatric Gastroenterology and Nutrition - JPGN. - : Lippincott Williams & Wilkins. - 0277-2116 .- 1536-4801. ; 60:6, s. 787-791
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To evaluate any potential correlation between anti-tissue transglutaminase antibodies of type immunoglobulin A (tTG-IgA) and the degree of gluten induced enteropathy in children participating in a screening study for celiac disease (CD) and to assess to what extent the revised ESPGHAN (European Society for Paediatric Gastroenterology, Hepatology and Nutrition) guidelines cover this group of patients.METHODS: This is a sub-study of a cross-sectional CD screening study, ETICS (Exploring the Iceberg of Celiacs in Sweden), a two-phased study performed during 2005-2006 and 2009-2010. The 13,279 participating children had a blood test obtained and those with positive tTG-IgA were recommended a small intestinal biopsy. The tTG-IgA levels at the time of biopsy were compared with the assessment of the biopsy.RESULTS: There were 267 children included, of whom 230 were diagnosed with CD. Out of all children, 67 children had low tTG-IgA levels (<5 U/mL), whereof 55% had Marsh 3 lesions. All children with tTG-IgA levels exceeding 10 times the upper limit of normal values of 5 U/mL, i.e. 50 U/mL, were diagnosed with CD. Lowering the cut-off to 3 U/mL, all but one child with 30 U/mL got CD diagnosis.CONCLUSION: By adapting the revised ESPGHAN criteria, biopsies could have been omitted in a fourth of all cases. Our results indicate, that the criteria might be useful even on screened children. Further studies are needed to confirm whether the 2012 ESPGHAN guidelines should be revised to also apply to the populations being screened.
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| 36. |
- Webb, Charlotta, et al.
(författare)
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High adherence to a gluten-free diet in adolescents with screening-detected celiac disease
- 2015
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Ingår i: Journal of Pediatric Gastroenterology and Nutrition - JPGN. - : Lippincott Williams & Wilkins. - 0277-2116 .- 1536-4801. ; 60:1, s. 54-59
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To evaluate the gluten-free diet (GFD) adherenceafter one year of follow-up in children with screening-detected celiac disease (CD) in a general population. METHODS: A total of 18,325 12 year olds were invited to participate in apopulation-based CD screening (ETICS- Exploring the Iceberg of Celiacs in Sweden), of whom 13,279 participated. In 240 children, CD was detected through elevated anti-tissue transglutaminase antibodies 2 (TG2-IgA) and verified by a small-intestinal biopsy. This sub-study included the 210 children with TG2-IgAevaluated both at the initialbiopsy occasion and at the one-year follow-up. GFD adherence was evaluated by a combination of TG2-IgA measurements and self-reported adherence (n = 193). RESULTS: After one year, 83% (179/210) had normalizedTG2-IgA levels (<5U/mL). Among those who had >50 U/mL at diagnosis,25% (16/63) still had elevated TG2-IgA but for the majority their initial values were more than halved. Most reported a high level ofGFD adherence ('always' 75%(158/193) and 'often' 14%(30/193)), and 75% (145/193) reported always adhereingcombined with normalized TG2-IgA. Although reporting that they were always adherent, 13 (6.7%) had not yet normalized their TG2-IgA levels completely, however, a majority of these initially had the highestTG2-IgA levels. CONCLUSIONS: GFD adherence is high in adolescents with CD detected by screening of the general population of Swedish 12yearolds. Almost all had normalized serology and reported GFD adherenceat the one-year follow-up. However, a few adolescents whoreported GFD adherence still had elevated TG2-IgA levelssuggesting more severe disease and/or non-adherence.
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| 37. |
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| 38. |
- Åhs, Fredrik, et al.
(författare)
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Biological preparedness and resistance to extinction of skin conductance responses conditioned to fear relevant animal pictures : A systematic review
- 2018
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Ingår i: Neuroscience and Biobehavioral Reviews. - : Elsevier. - 0149-7634 .- 1873-7528. ; 95, s. 430-437
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Tidskriftsartikel (refereegranskat)abstract
- Preparedness theory is one of the most influential ideas in explaining the origin of specific phobias. The theory proposes that fear conditioning is selective to animals that have posed a threat to survival throughout human evolution, and that acquired fear memories to such threats are resistant to extinction. We reviewed fear conditioning studies testing whether autonomic responses conditioned to pictures of snakes and spiders show greater resistance to extinction than neutral cues. We identified 32 fear conditioning experiments published in 23 studies including 1887 participants. Increased resistance to extinction of conditioned responses to snake and spider pictures was found in 10 (31%) of the experiments, whereas 22 (69%) experiments did not support the hypothesis. Thus, the body of evidence suggests that preparedness theory does not explain the origin of specific phobias.
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