| 1. |
- Asplund, Maria E., et al.
(författare)
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Water column dynamics of Vibrio in relation to phytoplankton community composition and environmental conditions in a tropical coastal area
- 2011
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Ingår i: Environmental Microbiology. - 1462-2912 .- 1462-2920. ; 13:10, s. 2738-2751
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Tidskriftsartikel (refereegranskat)abstract
- Vibrio abundance generally displays seasonal patterns. In temperate coastal areas, temperature and salinity influence Vibrio growth, whereas in tropical areas this pattern is not obvious. The present study assessed the dynamics of Vibrio in the Arabian Sea, 1-2 km off Mangalore on the south-west coast of India, during temporally separated periods. The two sampling periods were signified by oligotrophic conditions, and stable temperatures and salinity. Vibrio abundance was estimated by culture-independent techniques in relation to phytoplankton community composition and environmental variables. The results showed that the Vibrio density during December 2007 was 10- to 100-fold higher compared with the February-March 2008 period. High Vibrio abundance in December coincided with a diatom-dominated phytoplankton assemblage. A partial least squares (PLS) regression model indicated that diatom biomass was the primary predictor variable. Low nutrient levels suggested high water column turnover rate, which bacteria compensated for by using organic molecules leaking from phytoplankton. The abundance of potential Vibrio predators was low during both sampling periods; therefore it is suggested that resource supply from primary producers is more important than top-down control by predators.
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| 2. |
- Böhler, Christian, et al.
(författare)
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Multilayer Arrays for Neurotechnology Applications (MANTA): Chronically Stable Thin-Film Intracortical Implants
- 2023
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Ingår i: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 10:14
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Tidskriftsartikel (refereegranskat)abstract
- Flexible implantable neurointerfaces show great promise in addressing one of the major challenges of implantable neurotechnology, namely the loss of signal connected to unfavorable probe tissue interaction. The authors here show how multilayer polyimide probes allow high-density intracortical recordings to be combined with a reliable long-term stable tissue interface, thereby progressing toward chronic stability of implantable neurotechnology. The probes could record 10–60 single units over 5 months with a consistent peak-to-peak voltage at dimensions that ensure robust handling and insulation longevity. Probes that remain in intimate contact with the signaling tissue over months to years are a game changer for neuroscience and, importantly, open up for broader clinical translation of systems relying on neurotechnology to interface the human brain.
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| 3. |
- Gent, Matthew Raymond, et al.
(författare)
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The SAPP pipeline for the determination of stellar abundances and atmospheric parameters of stars in the core program of the PLATO mission
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 658
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Tidskriftsartikel (refereegranskat)abstract
- We introduce the SAPP (Stellar Abundances and atmospheric Parameters Pipeline), the prototype of the code that will be used to determine parameters of stars observed within the core program of the PLATO space mission. The pipeline is based on the Bayesian inference and provides effective temperature, surface gravity, metallicity, chemical abundances, and luminosity. The code in its more general version has a much wider range of potential applications. It can also provide masses, ages, and radii of stars and can be used with stellar types not targeted by the PLATO core program, such as red giants. We validate the code on a set of 27 benchmark stars that includes 19 FGK-type dwarfs, 6 GK-type subgiants, and 2 red giants. Our results suggest that combining various observables is the optimal approach, as this allows the degeneracies between different parameters to be broken and yields more accurate values of stellar parameters and more realistic uncertainties. For the PLATO core sample, we obtain a typical uncertainty of 27 (syst.) +/- 37 (stat.) K for T-eff, 0.00 +/- 0.01 dex for log g, 0.02 +/- 0.02 dex for metallicity [Fe/H], -0.01 +/- 0.03 R-circle dot for radii, -0.01 +/- 0.05 M-circle dot for stellar masses, and -0.14 +/- 0.63 Gyr for ages. We also show that the best results are obtained by combining the nu(max) scaling relation with stellar spectra. This resolves the notorious problem of degeneracies, which is particularly important for F-type stars.
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| 4. |
- Vomero, Maria, et al.
(författare)
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Conformable polyimide-based μECoGs : Bringing the electrodes closer to the signal source
- 2020
-
Ingår i: Biomaterials. - : Elsevier. - 0142-9612 .- 1878-5905. ; 255
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Tidskriftsartikel (refereegranskat)abstract
- Structural biocompatibility is a fundamental requirement for chronically stable bioelectronic devices. Newest neurotechnologies are increasingly focused on minimizing the foreign body response through the development of devices that match the mechanical properties of the implanted tissue and mimic its surface composition, often compromising on their robustness. In this study, an analytical approach is proposed to determine the threshold of conformability for polyimide-based electrocorticography devices. A finite element model was used to quantify the depression of the cortex following the application of devices mechanically above or below conformability threshold. Findings were validated in vivo on rat animal models. Impedance measurements were performed for 40 days after implantation to monitor the status of the biotic/abiotic interface with both conformable and non-conformable implants. Multi-unit activity was then recorded for 12 weeks after implantation using the most compliant device type. It can therefore be concluded that conformability is an essential prerequisite for steady and reliable implants which does not only depend on the Young's modulus of the device material: it strongly relies on the relation between tissue curvature at the implantation site and corresponding device's thickness and geometry, which eventually define the moment of inertia and the interactions at the material-tissue interface.
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| 5. |
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| 6. |
- Harland, Bruce, et al.
(författare)
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A Subdural Bioelectronic Implant to Record Electrical Activity from the Spinal Cord in Freely Moving Rats
- 2022
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Ingår i: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 9:20
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Tidskriftsartikel (refereegranskat)abstract
- Bioelectronic devices have found use at the interface with neural tissue to investigate and treat nervous system disorders. Here, the development and characterization of a very thin flexible bioelectronic implant inserted along the thoracic spinal cord in rats directly in contact with and conformable to the dorsal surface of the spinal cord are presented. There is no negative impact on hind-limb functionality nor any change in the volume or shape of the spinal cord. The bioelectronic implant is maintained in rats for a period of 12 weeks. The first subdural recordings of spinal cord activity in freely moving animals are presented; rats are plugged in via a recording cable and allowed to freely behave and move around on a raised platform. Recordings contained multiple distinct voltage waveforms spatially localize to individual electrodes. This device has great potential to monitor electrical signaling in the spinal cord after an injury and in the future, this implant will facilitate the identification of biomarkers in spinal cord injury and recovery, while enabling the delivery of localized electroceutical and chemical treatments.
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| 7. |
- Uhlén, Mathias, et al.
(författare)
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A human protein atlas for normal and cancer tissues based on antibody proteomics
- 2005
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Ingår i: Molecular & Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 4:12, s. 1920-1932
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Tidskriftsartikel (refereegranskat)abstract
- Antibody-based proteomics provides a powerful approach for the functional study of the human proteome involving the systematic generation of protein-specific affinity reagents. We used this strategy to construct a comprehensive, antibody-based protein atlas for expression and localization profiles in 48 normal human tissues and 20 different cancers. Here we report a new publicly available database containing, in the first version, similar to 400,000 high resolution images corresponding to more than 700 antibodies toward human proteins. Each image has been annotated by a certified pathologist to provide a knowledge base for functional studies and to allow queries about protein profiles in normal and disease tissues. Our results suggest it should be possible to extend this analysis to the majority of all human proteins thus providing a valuable tool for medical and biological research.
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| 8. |
- Vomero, Maria, et al.
(författare)
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On the longevity of flexible neural interfaces: Establishing biostability of polyimide-based intracortical implants
- 2022
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Ingår i: Biomaterials. - : Elsevier. - 0142-9612 .- 1878-5905. ; 281
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Tidskriftsartikel (refereegranskat)abstract
- Flexible neural implants are extremely favored, as the most successful strategy to promote probe-tissue integration and avoid severe gliosis relies on reducing the mechanical mismatch between probe and brain tissue. But what are the realistic requirements for achieving chronic recording stability? What are the critical dimensions and main factors determining glial scar-free device integration? To answer these questions, two types of hair-sized polyimide-based flexible intracortical (PIXI) arrays were fabricated, differing only in their cross-sectional area. Chronic tissue reaction to both types was evaluated in rats, and in different implantation setups. Interfacial stresses were found to play a critical role in long-term tissue integration. Still, all the devices provided high quality chronic recordings of single units and inflammatory gene expression was not significantly upregulated for larger devices. Our study points out that the most relevant factor in eliciting FBR is played by mechanical probe-tissue interactions, that polyimide is well tolerated by the tissue, and that a holistic design - considering material properties, geometrical dimensions and assembling techniques - is the key towards longevity and long-term performance of intracortical probes. The optimization of only one parameter did not yet lead to the successful translation of research accomplishments into chronic preclinical and clinical applications.
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| 9. |
- Andersson, Jennie, et al.
(författare)
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In Vitro Therapy Modeling of HER2 Targeting Therapy in Disseminated Prostate Cancer
- 2014
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Ingår i: International Journal of Oncology. - : Spandidos Publications. - 1019-6439 .- 1791-2423. ; 45:5, s. 2153-2158
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Tidskriftsartikel (refereegranskat)abstract
- Prostate cancer (PCa) is the most common cancer type among men. Treatments against advanced PCa are limited and in many cases only palliative. In a later, androgent independent, stage of PCa androgen receptors can be activated without interaction with ligand, i.e., by receptors of tyrosine kinase (RTK) family in the outlaw pathway. Human epidermal growth factor receptors HER2 and EGFR belong to RTK-family. HER2 is one of the main actors in the outlaw pathway with EGFR as the preferable heterodimerizing partner. We hypothesized that information on HER2 expression in advanced PCa could be useful for selection of patients for anti-RTK therapy and monitoring of therapy response. A panel of PCa cell lines (LNCap, PC3, DU-145) was subjected to a 8-week treatment using drugs influencing the RTK: trastuzumab (anti‑HER2), 17-DMAG (Hsp90 inhibitor), alone or in combination, and their HER2 and EGFR expressions were compared with non-treated cells. Treatment with trastuzumab decreased proliferation of LNCap and DU-145 cell lines, while 17-DMAG and trastuzumab/17‑DMAG combination affected all three cell lines. HER2 expression was significantly increased in PC3 cells, the most resistant cell line. On the contrary, in responding cells (LNCap and DU-145) HER2 expression decreased, accompanied by increased EGFR expression. However, additional treatment of cells with cetuximab (anti‑EGFR) did not give any additive effect to trastuzumab. In this study the response to anti-RTK therapy proved to vary between different PCa cell lines. We have demonstrated that RTK targeting treatments may affect the phenotypic profile of PCa tumor cells that correlates with therapy outcome. Observation of such changes during treatment could be used for monitoring and an improved therapy outcome.
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| 10. |
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| 11. |
- Andersson, Mathias H, 1976-, et al.
(författare)
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Importance of Using Multiple Sampling Methodologies for Estimating of Fish Community Composition in Offshore Wind Power Construction Areas of the Baltic Sea
- 2007
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 36:8, s. 634-636
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Tidskriftsartikel (refereegranskat)abstract
- It is standard procedure that an Environmental Impact Assessment (EIA) is conducted before larger constructions are built. To adequately describe the impact, methods used in an EIA should be carefully adapted considering both the character of the constructions under development and the environment that will be affected. Various sampling techniques are applied to estimate fish abundances and species composition. Methods used, including trawling, seine and gill netting, angling, echo-sound sampling, fishery data, video recordings, dredging, and visual counts using SCUBA, will all give different estimates of fish community composition.
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| 12. |
- Angenete, Eva, 1972, et al.
(författare)
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Stenting for colorectal cancer obstruction compared to surgery-a study of consecutive patients in a single institution.
- 2012
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Ingår i: International journal of colorectal disease. - : Springer Science and Business Media LLC. - 1432-1262 .- 0179-1958. ; 27:5, s. 665-670
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Colonic obstruction is a common complication to colorectal cancer and surgical treatment is associated with high morbidity and mortality. Stenting has emerged as an alternative to surgery. The aim of this study was to compare short-term morbidity, mortality and hospital stay between treatment with self-expandable metallic stent and emergency surgery performed at our department during a 5-year period in a non-randomized setting. METHODS: Patients with colonic obstruction due to rectal or colon cancer referred to the Endoscopic Unit or Surgical Department for insertion of a colonic stent between 1 August 2003 and 1 August 2008 were prospectively registered and followed (n=112). A control group was identified using the hospital records of operations with the International Classification Code-10 (ICD-10) for bowel obstruction and colorectal cancer (n=60). Age, gender, indication, preoperative investigations, surgical procedure, complications and procedure-related mortality were registered. Patients were followed in accordance with local guidelines. RESULTS: The complication rate was similar in the two groups, although there was a trend toward a higher number of severe complications in the surgical group. The hospital stay was significantly lower in the stent group, median of 4 vs. 9days (p<0.0001). The procedure-related mortality was lower in the stent group; 7% vs. 20% (p<0.05). CONCLUSIONS: Stenting can be safely performed with lower or similar complication rate and lower mortality rate compared to surgery and results in significantly shorter hospital stay. The results support stenting as the treatment of choice in patients with acute colonic obstruction, especially in disseminated disease.
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| 13. |
- Aqrawe, Zaid, et al.
(författare)
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Stretchable Electronics Based on Laser Structured, Vapor Phase Polymerized PEDOT/Tosylate
- 2020
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- The fabrication of stretchable conductive material through vapor phase polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) is presented alongside a method to easily pattern these materials with nanosecond laser structuring. The devices were constructed from sheets of vapor phase polymerized PEDOT doped with tosylate on pre-stretched elastomeric substrates followed by laser structuring to achieve the desired geometrical shape. Devices were characterized for electrical conductivity, morphology, and electrical integrity in response to externally applied strain. Fabricated PEDOT sheets displayed a conductivity of 53.1 ± 1.2 S cm−1; clear buckling in the PEDOT microstructure was observed as a result of pre-stretching the underlying elastomeric substrate; and the final stretchable electronic devices were able to remain electrically conductive with up to 100% of externally applied strain. The described polymerization and fabrication steps achieve highly processable and patternable functional conductive polymer films, which are suitable for stretchable electronics due to their ability to withstand externally applied strains of up to 100%.
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| 14. |
- Asplund, Eva, 1942-, et al.
(författare)
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Vårt uppdrag är utveckling : hållbar utveckling och regional tillväxt
- 2010
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Rapport (populärvet., debatt m.m.)abstract
- Boken handlar om erfarenheterna från några svenska regioners ansträngningar att omsätta hållbar utveckling inom ramen för regionalt tillväxtarbete, och behandlar bland annat lärandeprocesser och integration av miljöfrågor i en organisations arbete. Syftet är att inspirera till kritisk reflektion och diskussion vilket utgör en avgörande grund för förändring och lärande. I grunden handlar boken om vad arbetet med regional utveckling och tillväxt är och kan vara samt vilken roll hållbar utveckling spelar i arbetet.
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| 15. |
- Asplund, Isabel, et al.
(författare)
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Samverkan inom socialtjänsten kring våld i nära relationer : Erfarenheter, utmaningar och möjligheter
- 2022
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Panelsamtal om socialtjänstens insatser för att hantera våld i nära relationer, särskilt de olika former av våld som berör barn. Samtalet kommer att kretsa kring frågan om hur ett mer samordnat och barncentrerat system av insatser mot våld kan åstadkommas, ett system där våldsutsatta barn både kan få det skydd och stöd de behöver, och vara delaktiga i alla processer som berör dem. Utgångspunkten är de olika medverkandes erfarenheter av problematiken kring våld, barn och samordning inom socialtjänsten och mellan socialtjänst och andra aktörer. Utifrån dessa erfarenheter reflekterar paneldeltagarna tillsammans reflektera över de utmaningar respektive utvecklingsmöjligheter när det gäller att utveckla mer samordnade interventioner kring våld i nära relationer.Deltar i panelsamtalet gör: Isabel Asplund, projektledare Islandsprojektet Stockholm, Maria Eriksson, professor Marie Cederschiöld högskola, Anna Friberg, biträdande enhetschef i Enheten för stöd och skydd och chef över Barnahus Stockholm, Frida Malm, biträdande enhetschef, Relationsvåldscentrum RVC Innerstad, Liselotte Tronders, biträdande enhetschef Stockholm stads SocialjourPanelsamtalet modereras av Martin Börjeson.
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| 16. |
- Asplund, Kjell, et al.
(författare)
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Diagnostic procedures, treatments, and outcomes in stroke patients admitted to different types of hospitals
- 2015
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Ingår i: Stroke. - : Lippincott Williams & Wilkins. - 0039-2499 .- 1524-4628. ; 46:3, s. 806-812
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Tidskriftsartikel (refereegranskat)abstract
- Background and Purpose: In many countries, including Sweden, initiatives have been taken to reduce between-hospital differences in the quality of stroke services. We have explored to what extent hospital type (university, specialized nonuniversity, or community hospital) influences hospital performance. Methods: Riksstroke collects clinical data during hospital stay (national coverage 94%). Follow-up data at 3 months were collected using administrative registers and a questionnaire completed by surviving patients (response rate 88%). Structural data were collected from a questionnaire completed by hospital staff (response rate 100%). Multivariate analyses with adjustment for clustering were used to test differences between types of hospitals. Results: The proportion of patients admitted directly to a stroke unit was highest in community hospitals and lowest in university hospitals. Magnetic resonance, carotid imaging, and thrombectomy were more frequently performed in university hospitals, and the door-to-needle time for thrombolysis was shorter. Secondary prevention with antihypertensive drugs was used less often, and outpatient follow-up was less frequent in university hospitals. Fewer patients in community hospitals were dissatisfied with their rehabilitation. After adjusting for possible confounders, poor outcome (dead or activities of daily living dependency 3 months after stroke) was not significantly different between the 3 types of hospital. Conclusions: In a setting with national stroke guidelines, stroke units in all hospitals, and measurement of hospital performance and benchmarking, outcome (after case-mix adjustment) is similar in university, specialized nonuniversity, and community hospitals. There seems to be fewer barriers to organizing well-functioning stroke services in community hospitals compared with university hospitals.
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| 17. |
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| 18. |
- Asplund, Maria, 1978-, et al.
(författare)
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Biocompatibility of PEDOT/biomolecular composites intended for neural communication electrodes
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Annan publikation (populärvet., debatt m.m.)abstract
- Electrodes of the conjugated polymer poly(3,4-ethylene dioxythiophene) (PEDOT) have been shown to possess very attractive electrochemical properties for functional electrical stimulation (FES) or recording in the nervous system. Biomolecules already present in nervous tissue, added as counter ions in PEDOT electropolymerisation, could be a route to further improve the biomaterial properties of PEDOT, eliminating the need of surfactant counter ions like docedyl benzene sulphonate (DBS) or polystyrene sulphonate (PSS) in the polymerisation process. Such PEDOT/biomolecular composites using heparin, or hyaluronic acid, have been electrochemically investigated in a previous study and have been shown to retain the attractive electrochemical properties already proven for PEDOT:PSS. The aim of the present study is to evaluate biocompatibility of these PEDOT/biomolecular composites in vitro and also evaluate PEDOT:heparin biocompatibility in cortical tissue in vivo. Hereby, we also aim to identify a suitable test protocol, that can be used in future evaluations when further material developments are made. Material toxicity was first tested on cell lines, both through a standardised agarose overlay assay on L929 fibroblasts, and through elution tests on human neuroblastoma SH-SY5Y cells. Subsequently, a biocompatibility in vivo test was performed using PEDOT:heparin coated platinum probes implanted in the cerebral cortex of Sprague-Dawley rats. Tissue was collected at three weeks and six weeks of implantation and evaluated by immunohistochemistry. No cytotoxic response was seen to any of the PEDOT:biomolecular composites tested here. Furthermore, elution tests were found to be a practical and effective way of screening materials for toxicity and had a clear advantage over the agarose overlay assay, which was difficult to apply on other cell types than fibroblasts. Elution tests would therefore be recommendable as a screening method, at all stages of material development. In the in vivo tests, the stiffness of the platinum substrate was a significant problem, and extensive glial scarring was seen in most cases irrespective of implant material. However, quantification of immunological response through distance measurements from implant site to closest neuron, and counting of macrophage densities in proximity to polymer surface, was comparable to those of platinum controls. These results indicate that PEDOT:heparin surfaces were as compatible with cortical tissue as pure platinum controls.
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| 19. |
- Asplund, Maria, 1978-, et al.
(författare)
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Composite biomolecule/PEDOT materials for neural electrodes
- 2008
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Ingår i: Biointerphases. - NY : American Institute of Physics. - 1559-4106 .- 1934-8630. ; 3:3, s. 83-93
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Tidskriftsartikel (refereegranskat)abstract
- Electrodes intended for neural communication must be designed to meet boththe electrochemical and biological requirements essential for long term functionality. Metallic electrode materials have been found inadequate to meet theserequirements and therefore conducting polymers for neural electrodes have emergedas a field of interest. One clear advantage with polymerelectrodes is the possibility to tailor the material to haveoptimal biomechanical and chemical properties for certain applications. To identifyand evaluate new materials for neural communication electrodes, three chargedbiomolecules, fibrinogen, hyaluronic acid (HA), and heparin are used ascounterions in the electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The resultingmaterial is evaluated electrochemically and the amount of exposed biomoleculeon the surface is quantified. PEDOT:biomolecule surfaces are also studiedwith static contact angle measurements as well as scanning electronmicroscopy and compared to surfaces of PEDOT electrochemically deposited withsurfactant counterion polystyrene sulphonate (PSS). Electrochemical measurements show that PEDOT:heparinand PEDOT:HA, both have the electrochemical properties required for neuralelectrodes, and PEDOT:heparin also compares well to PEDOT:PSS. PEDOT:fibrinogen isfound less suitable as neural electrode material.
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| 20. |
- Asplund, Maria, 1978-
(författare)
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Conjugated Polymers for Neural Interfaces : Prospects, possibilities and future challenges
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Within the field of neuroprosthetics the possibility to use implanted electrodes for communication with the nervous system is explored. Much effort is put into the material aspects of the electrode implant to increase charge injection capacity, suppress foreign body response and build micro sized electrode arrays allowing close contact with neurons. Conducting polymers, in particular poly(3,4-ethylene dioxythiophene) (PEDOT), have been suggested as materials highly interesting for such neural communication electrodes. The possibility to tailor the material both mechanically and biochemically to suit specific applications, is a substantial benefit with polymers when compared to metals. PEDOT also have hybrid charge transfer properties, including both electronic and ionic conduction, which allow for highly efficient charge injection. Part of this thesis describes a method of tailoring PEDOT through exchanging the counter ion used in electropolymerisation process. Commonly used surfactants can thereby be excluded and instead, different biomolecules can be incorporated into the polymer. The electrochemical characteristics of the polymer film depend on the ion. PEDOT electropolymerised with heparin was here determined to have the most advantageous properties. In vitro methods were applied to confirm non-cytotoxicity of the formed PEDOT:biomolecular composites. In addition, biocompatibility was affirmed for PEDOT:heparin by evaluation of inflammatory response and neuron density when implanted in rodent cortex. One advantage with PEDOT often stated, is its high stability compared to other conducting polymers. A battery of tests simulating the biological environment was therefore applied to investigate this stability, and especially the influence of the incorporated heparin. These tests showed that there was a decline in the electroactivity of PEDOT over time. This also applied in phosphate buffered saline at body temperature and in the absence of other stressors. The time course of degradation also differed depending on whether the counter ion was the surfactant polystyrene sulphonate or heparin, with a slightly better stability for the former. One possibility with PEDOT, often overlooked for biological applications, is the use of its semi conducting properties in order to include logic functions in the implant. This thesis presents the concept of using PEDOT electrochemical transistors to construct textile electrode arrays with in-built multiplexing. Using the electrolyte mediated interaction between adjacent PEDOT coated fibres to switch the polymer coat between conducting and non conducting states, then transistor function can be included in the conducting textile. Analogue circuit simulations based on experimentally found transistor characteristics proved the feasibility of these textile arrays. Developments of better polymer coatings, electrolytes and encapsulation techniques for this technology, were also identified to be essential steps in order to make these devices truly useful. In summary, this work shows the potential of PEDOT to improve neural interfaces in several ways. Some weaknesses of the polymer and the polymer electronics are presented and this, together with the epidemiological data, should point in the direction for future studies within this field.
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| 21. |
- Asplund, Maria, et al.
(författare)
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Construction of wire electrodesand 3D woven logicas a potential technology forneuroprosthetic implants
- 2008
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- New strategies to improve neuron coupling to neuroelectronic implants are needed. In particular, tomaintain functional coupling between implant and neurons, foreign body response like encapsulation must meminimized. Apart from modifying materials to mitigate encapsulation it has been shown that with extremely thinstructures, encapsulation will be less pronounced. We here utilize wire electrochemical transistors (WECTs) usingconducting polymer coated fibers. Monofilaments down to 10 μm can be successfully coated and weaved intocomplex networks with built in logic functions, so called textile logic. Such systems can control signal patterns at alarge number of electrode terminals from a few addressing fibres. Not only is fibre size in the range where lessencapsulation is expected but textiles are known to make successful implants because of their soft and flexiblemechanical properties. Further, textile fabrication provides versatility and even three dimensional networks arepossible. Three possible architectures for neuroelectronic systems are discussed. WECTs are sensitive to dehydrationand materials for better durability or improved encapsulation is needed for stable performance in biologicalenvironments.
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| 22. |
- Asplund, Maria. E., 1970, et al.
(författare)
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Dynamics and fate of blue carbon in a mangrove-seagrass seascape : influence of landscape configuration and land-use change
- 2021
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Ingår i: Landscape Ecology. - : Springer. - 0921-2973 .- 1572-9761. ; 36, s. 1489-1509
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Tidskriftsartikel (refereegranskat)abstract
- Context Seagrass meadows act as efficient natural carbon sinks by sequestering atmospheric CO2 and through trapping of allochthonous organic material, thereby preserving organic carbon (C-org) in their sediments. Less understood is the influence of landscape configuration and transformation (land-use change) on carbon sequestration dynamics in coastal seascapes across the land-sea interface. Objectives We explored the influence of landscape configuration and degradation of adjacent mangroves on the dynamics and fate of C-org in seagrass habitats. Methods Through predictive modelling, we assessed sedimentary C-org content, stocks and source composition in multiple seascapes (km-wide buffer zones) dominated by different seagrass communities in northwest Madagascar. The study area encompassed seagrass meadows adjacent to intact and deforested mangroves. Results The sedimentary C-org content was influenced by a combination of landscape metrics and inherent habitat plant- and sediment-properties. We found a strong land-to-sea gradient, likely driven by hydrodynamic forces, generating distinct patterns in sedimentary C-org levels in seagrass seascapes. There was higher C-org content and a mangrove signal in seagrass surface sediments closer to the deforested mangrove area, possibly due to an escalated export of C-org from deforested mangrove soils. Seascapes comprising large continuous seagrass meadows had higher sedimentary C-org levels in comparison to more diverse and patchy seascapes. Conclusion Our results emphasize the benefit to consider the influence of seascape configuration and connectivity to accurately assess C-org content in coastal habitats. Understanding spatial patterns of variability and what is driving the observed patterns is useful for identifying carbon sink hotspots and develop management prioritizations.
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| 23. |
- Asplund, Maria. E., 1970
(författare)
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Ecological aspects of marine Vibrio bacteria - Exploring relationships to other organisms and a changing environment
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Heterotrophic bacteria of the genus Vibrio are indigenous in the marine environment although environmental cues regulate their growth and distribution. The attention brought to this genus is due to its many species/strains that are pathogenic to humans and other organisms. Vibrio abundances are strongly coupled to water temperature and salinity but abundance dynamics occur even where these hydrographical parameters are stable. In this thesis, I have studied Vibrio dynamics in relation to other organisms such as phytoplankton (papers I, II and III) and a bivalve host-organism (paper IV) in a changing environment where increasing temperature (paper III) and ocean acidification (paper IV) may influence survival and proliferation of these bacteria. In particular paper I showed that in a tropical coastal area, where the water temperature and salinity were stable across seasons, abundances of Vibrio were tightly coupled to phytoplankton biomass and community composition. A diatom bloom during December seemed to support high numbers of vibrios in waters with otherwise low levels of dissolved organic carbon. Paper II further supports that some phytoplankton can favor Vibrio growth while others seem to have a negative influence on Vibrio abundances. For instance, Skeletonema tropicum, a common diatom in Indian coastal waters, easily eradicated Vibrio parahaemolyticus from sea water in our experiments. In temperate marine areas culturable Vibrio predominantly occurs in the water column during the warmer months. Sediments are suggested to be potential reservoirs when conditions in the water-column are harsh. Accordingly, in paper III we showed that cold-water sediments from geographically separate areas in a boreal region of Scandinavia all contained relative high abundances of total Vibrio spp. and that all sediments also included culturable Vibrio. In agreement with paper I, the fresh input of organic material from phytoplankton blooms, for which chlorophyll a was used as a proxy, seemed to positively influence Vibrio abundances also in the sediments (paper III). Therefore, the pelagic-benthic coupling which can supply the sediments with biomass from the primary production could influence the abundance of Vibrio spp. Increasing temperature had variable influence on sediment-associated Vibrio abundance, with a significant increase in abundances in sediments originating from one area when the temperature reached over 21°C and a generally negative influence of increasing temperature on abundances in sediments originating from another area (paper III). This suggests that the sediments contained different Vibrio communities with varying temperature tolerance traits. Rising levels of carbon dioxide in the atmosphere does not only lead to higher water temperature through the green house effect, but also to acidification of the oceans. Paper IV illustrated how a common bivalve pathogen, Vibrio tubiashii, can be favored in the interaction with a calcifying bivalve host, Mytilus edulis, when this host-pathogen combination was exposed to levels of ocean acidification projected to occur by the end of the 21st century. Thus, global environmental changes may enhance the probability of Vibrio infections in higher organisms.
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| 24. |
- Asplund, Maria. E., 1970, et al.
(författare)
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Methane Emissions From Nordic Seagrass Meadow Sediments
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Shallow coastal soft bottoms are important carbon sinks. Submerged vegetation has been shown to sequester carbon, increase sedimentary organic carbon (C-org) and thus suppress greenhouse gas (GHG) emissions. The ongoing regression of seagrass cover in many areas of the world can therefore lead to accelerated emission of GHGs. In Nordic waters, seagrass meadows have a high capacity for carbon storage, with some areas being recognized as blue carbon hotspots. To what extent these carbon stocks lead to emission of methane (CH4) is not yet known. We investigated benthic CH4 emission (i.e., net release from the sediment) in relation to seagrass (i.e. Zostera marina) cover and sedimentary C-org content (%) during the warm summer period (when emissions are likely to be highest). Methane exchange was measured in situ with benthic chambers at nine sites distributed in three regions along a salinity gradient from similar to 6 in the Baltic Sea (Finland) to similar to 20 in Kattegat (Denmark) and similar to 26 in Skagerrak (Sweden). The net release of CH4 from seagrass sediments and adjacent unvegetated areas was generally low compared to other coastal habitats in the region (such as mussel banks and wetlands) and to other seagrass areas worldwide. The lowest net release was found in Finland. We found a positive relationship between CH4 net release and sedimentary C-org content in both seagrass meadows and unvegetated areas, whereas no clear relationship between seagrass cover and CH4 net release was observed. Overall, the data suggest that Nordic Zostera marina meadows release average levels of CH4 ranging from 0.3 to 3.0 mu g CH4 m(-2) h(-1), which is at least 12-78 times lower (CO2 equivalents) than their carbon accumulation rates previously estimated from seagrass meadows in the region, thereby not hampering their role as carbon sinks. Thus, the relatively weak CH4 emissions from Nordic Z. marina meadows will not outweigh their importance as carbon sinks under present environmental conditions.
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| 25. |
- Asplund, Maria. E., 1970, et al.
(författare)
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Ocean acidification and host-pathogen interactions: blue mussels, Mytilus edulis, encountering Vibrio tubiashii
- 2014
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912 .- 1462-2920. ; 16:4, s. 1029-1039
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification (OA) can shift the ecological balance between interacting organisms. In this study, we have used a model system to illustrate the interaction between a calcifying host organism, the blue mussel Mytilus edulis and a common bivalve bacterial pathogen, Vibrio tubiashii, with organisms being exposed to a level of acidification projected to occur by the end of the 21st century. OA exposures of the mussels were carried out in relative long-term (4 months) and short-term (4 days) experiments. We found no effect of OA on the culturability of V.tubiashii, in broth or in seawater. OA inhibited mussel shell growth and impaired crystalline shell structures but did not appear to affect mussel immune parameters (i.e haemocyte counts and phagocytotic capacity). Despite no evident impact on host immunity or growth and virulence of the pathogen, V.tubiashii was clearly more successful in infecting mussels exposed to long-term OA compared to those maintained under ambient conditions. Moreover, OA exposed V.tubiashii increased their viability when exposed to haemocytes of OA-treated mussel. Our findings suggest that even though host organisms may have the capacity to cope with periods of OA, these conditions may alter the outcome of host–pathogen interactions, favouring the success of the latter.
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| 26. |
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| 27. |
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| 28. |
- Asplund, Maria, et al.
(författare)
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Electroactive polymers for neural interfaces
- 2010
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Ingår i: Polymer chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 1:9, s. 1374-1391
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Forskningsöversikt (refereegranskat)abstract
- Development of electroactive conjugated polymers, for the purpose of recording and eliciting signals in the neural systems in humans, can be used to fashion the interfaces between the two signalling systems of electronics and neural systems. The design of desirable chemical, mechanical and electrical properties in the electroactive polymer electrodes, and the means of integration of these into biological systems, are here reviewed.
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| 29. |
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| 30. |
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| 31. |
- Asplund, Maria, 1978-, et al.
(författare)
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Incidence of traumatic peripheral nerve injuries and amputations in Sweden between 1998 and 2006
- 2008
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Ingår i: Neuroepidemiology. - Basel : Kargel, AG. - 0251-5350 .- 1423-0208.
-
Tidskriftsartikel (refereegranskat)abstract
- Background: To define the epidemiological pattern of nerve injuries and traumatic amputations in Sweden, 1998-2006, and investigate possible targets for emerging neural engineering and neuroprosthetic technologies. Methods: The Swedish Hospital Discharge Register was used as basis of information, including data from all public in-patient care, excluding out-patient data. ICD-10 codes were screened for nerve injuries and traumatic amputations of high incidence or in-patient care time. Selected codes, causing factors, age and gender distribution were discussed in detail, and potential targets for tailored solutions were identified. Results: Incidence rate was determined to 13.9 for nerve injuries and 5.21 for amputations per 100 000 person-yrs. The majority of injuries occurred at wrist and hand level although it could be concluded that these are often minor injuries requiring less than a week of hospitalization. The single most care consuming nerve injury was brachial plexus injury constituting, in average, 68 injuries and 960 hospital days annually. When minor amputations of fingers and toes were disregarded, most frequent site of amputation was between knee and ankle (24 patients / year). Conclusions: Based on analysis of incidence and care time, we find that brachial plexus injuries and lower leg amputations should be primary targets of these new technologies.
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| 32. |
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| 33. |
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| 34. |
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| 35. |
- Asplund, Maria, 1978-, et al.
(författare)
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Wire electronics and woven logic, as a potential technology for neuroelectronic implants
-
Annan publikation (populärvet., debatt m.m.)abstract
- New strategies to improve neuron coupling to neuroelectronic implants are needed. In particular, to maintain functional coupling between implant and neurons, foreign body response like encapsulation must me minimized. Apart from modifying materials to mitigate encapsulation it has been shown that with extremely thin structures, encapsulation will be less pronounced. We here utilize wire electrochemical transistors (WECTs) using conducting polymer coated fibers. Monofilaments down to 10 μm can be successfully coated and weaved into complex networks with built in logic functions, so called textile logic. Such systems can control signal patterns at a large number of electrode terminals from a few addressing fibres. Not only is fibre size in the range where less encapsulation is expected but textiles are known to make successful implants because of their soft and flexible mechanical properties. Further, textile fabrication provides versatility and even three dimensional networks are possible. Three possible architectures for neuroelectronic systems are discussed. WECTs are sensitive to dehydration and materials for better durability or improved encapsulation is needed for stable performance in biological environments.
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| 36. |
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| 37. |
- Basile, Anna Maria, et al.
(författare)
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Age, hypertension, and lacunar stroke are the major determinants of the severity of age-related white matter changes
- 2006
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Ingår i: CEREBROVASCULAR DISEASES. - : S. Karger AG. - 1015-9770 .- 1421-9786. ; 21:5-6, s. 315-322
-
Tidskriftsartikel (refereegranskat)abstract
- <i>Background:</i> Age-related white matter changes (ARWMC), seen on neuroimaging with high frequency in older people, are thought to be consequent to the effect of vascular risk factors and vascular diseases including hypertension and stroke. Among the proofs conventionally required for a factor to be considered a risk factor for a definite pathology, there is the demonstration of a trend in risk exposure related to disease severity. We sought whether such a trend existed in the association of vascular risk factors or comorbidities with the severity of ARWMC aiming particularly at further elucidating the relative roles of hypertension and stroke in this regard. <i>Methods:</i> The LADIS (Leukoaraiosis and Disability) Study is evaluating the role of ARWMC as an independent determinant of the transition to disability in the elderly. Six hundred and thirty-nine nondisabled subjects (mean age 74.1 ± 5.0, M/F: 288/351) with ARWMC of different severity grades on MRI (mild, moderate, or severe according to the Fazekas scale) were assessed at baseline for demographics, vascular risk factors, and comorbidities, and are being followed up for 3 years. <i>Results:</i> Age, frequency of hypertension and history of stroke increased along with increasing ARWMC severity independently of other factors. For hypertension, however, this occurred only in subjects without a stroke history, while for stroke history, it mainly depended on lacunar stroke. The amount of cigarettes smoked and the interaction between hypercholesterolemia and smoking predicted only the most severe ARWMC grade. <i>Conclusions:</i> The LADIS Study confirms that age, hypertension and lacunar strokes are the major determinants of ARWMC. Smoking and hypercholesterolemia provide additional risk.
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| 38. |
- Basile, Anna Maria, et al.
(författare)
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Age, hypertension, and lacunar stroke are the major determinants of the severity of age-related white matter changes. The LADIS (Leukoaraiosis and Disability in the Elderly) Study.
- 2006
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Ingår i: Cerebrovasc Dis. - : S. Karger AG. - 1015-9770 .- 1421-9786. ; 21:5-6, s. 315-22
-
Tidskriftsartikel (refereegranskat)abstract
- <i>Background:</i> Age-related white matter changes (ARWMC), seen on neuroimaging with high frequency in older people, are thought to be consequent to the effect of vascular risk factors and vascular diseases including hypertension and stroke. Among the proofs conventionally required for a factor to be considered a risk factor for a definite pathology, there is the demonstration of a trend in risk exposure related to disease severity. We sought whether such a trend existed in the association of vascular risk factors or comorbidities with the severity of ARWMC aiming particularly at further elucidating the relative roles of hypertension and stroke in this regard. <i>Methods:</i> The LADIS (Leukoaraiosis and Disability) Study is evaluating the role of ARWMC as an independent determinant of the transition to disability in the elderly. Six hundred and thirty-nine nondisabled subjects (mean age 74.1 ± 5.0, M/F: 288/351) with ARWMC of different severity grades on MRI (mild, moderate, or severe according to the Fazekas scale) were assessed at baseline for demographics, vascular risk factors, and comorbidities, and are being followed up for 3 years. <i>Results:</i> Age, frequency of hypertension and history of stroke increased along with increasing ARWMC severity independently of other factors. For hypertension, however, this occurred only in subjects without a stroke history, while for stroke history, it mainly depended on lacunar stroke. The amount of cigarettes smoked and the interaction between hypercholesterolemia and smoking predicted only the most severe ARWMC grade. <i>Conclusions:</i> The LADIS Study confirms that age, hypertension and lacunar strokes are the major determinants of ARWMC. Smoking and hypercholesterolemia provide additional risk.
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| 39. |
- Bergemann, Maria, et al.
(författare)
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The Gaia-ESO Survey : Hydrogen lines in red giants directly trace stellar mass
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 594
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Tidskriftsartikel (refereegranskat)abstract
- Red giant stars are perhaps the most important type of stars for Galactic and extra-galactic archaeology: they are luminous, occur in all stellar populations, and their surface temperatures allow precise abundance determinations for many different chemical elements. Yet, the full star formation and enrichment history of a galaxy can be traced directly only if two key observables can be determined for large stellar samples: age and chemical composition. While spectroscopy is a powerful method to analyse the detailed abundances of stars, stellar ages are the missing link in the chain, since they are not a direct observable. However, spectroscopy should be able to estimate stellar masses, which for red giants directly infer ages provided their chemical composition is known. Here we establish a new empirical relation between the shape of the hydrogen line in the observed spectra of red giants and stellar mass determined from asteroseismology. The relation allows determining stellar masses and ages with an accuracy of 10-15%. The method can be used with confidence for stars in the following range of stellar parameters: 4000 < T-eff < 5000 K, 0.5 < log g < 3.5, -2.0 < [ Fe/H] < 0.3, and luminosities log L/L-Sun < 2.5. Our analysis provides observational evidence that the H-alpha spectral characteristics of red giant stars are tightly correlated with their mass and therefore their age. We also show that the method samples well all stellar populations with ages above 1 Gyr. Targeting bright giants, the method allows obtaining simultaneous age and chemical abundance information far deeper than would be possible with asteroseismology, extending the possible survey volume to remote regions of the Milky Way and even to neighbouring galaxies such as Andromeda or the Magellanic Clouds even with current instrumentation, such as the VLT and Keck facilities.
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| 40. |
- Bianchi, Michele, et al.
(författare)
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Poly(3,4‐ethylenedioxythiophene)‐Based Neural Interfaces for Recording and Stimulation: Fundamental Aspects and In Vivo Applications
- 2022
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Ingår i: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 9:12
-
Forskningsöversikt (refereegranskat)abstract
- Next‐generation neural interfaces for bidirectional communication with the central nervous system aim to achieve the intimate integration with the neural tissue with minimal neuroinflammatory response, high spatio‐temporal resolution, very high sensitivity, and readout stability. The design and manufacturing of devices for low power/low noise neural recording and safe and energy‐efficient stimulation that are, at the same time, conformable to the brain, with matched mechanical properties and biocompatibility, is a convergence area of research where neuroscientists, materials scientists, and nanotechnologists operate synergically. The biotic–abiotic neural interface, however, remains a formidable challenge that prompts for new materials platforms and innovation in device layouts. Conductive polymers (CP) are attractive materials to be interfaced with the neural tissue and to be used as sensing/stimulating electrodes because of their mixed ionic‐electronic conductivity, their low contact impedance, high charge storage capacitance, chemical versatility, and biocompatibility. This manuscript reviews the state‐of‐the‐art of poly(3,4‐ethylenedioxythiophene)‐based neural interfaces for extracellular recording and stimulation, focusing on those technological approaches that are successfully demonstrated in vivo. The aim is to highlight the most reliable and ready‐for‐clinical‐use solutions, in terms of materials technology and recording performance, other than spot major limitations and identify future trends in this field.
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| 41. |
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| 42. |
- Björk, Mats, 1960-, et al.
(författare)
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The amount of light reaching the leaves in seagrass (Zostera marina) meadows.
- 2021
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 16:9
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows, and other submerged vegetated habitats, support a wide range of essential ecological services, but the true extents of these services are in many ways still not quantified. One important tool needed to assess and model many of these services is accurate estimations of the systems´ primary productivity. Such productivity estimations require an understanding of the underwater light field, especially regarding the amount of light that actually reaches the plants' photosynthetic tissue. In this study, we tested a simple practical approach to estimate leaf light exposure, relative to incoming light at the canopy, by attaching light sensitive film at different positions on leaves of Zostera marina, eelgrass, in four seagrass meadows composed of different shoot density and at two different depths. We found that the light reaching the leaves decreased linearly down through the canopy. While the upper parts of the leaves received approximately the same level of light (photosynthetic photon flux density, PPFD) as recorded with a PAR meter at the canopy top, the average light that the seagrass leaves were exposed to varied between 40 and 60% of the light on top of the canopy, with an overall average of 48%. We recommend that actual light interception is measured when assessing or modelling light depending processes in submerged vegetation, but if this is not achievable a rough estimation for vegetation similar to Z. marina would be to use a correction factor of 0.5 to compensate for the reduced light due to leaf orientation and internal shading.
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| 43. |
- Boehler, Christian, et al.
(författare)
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Tutorial: guidelines for standardized performance tests for electrodes intended for neural interfaces and bioelectronics
- 2020
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Ingår i: Nature Protocols. - : Springer Nature. - 1754-2189 .- 1750-2799. ; 15:11, s. 3557-3578
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Forskningsöversikt (refereegranskat)abstract
- Implantable neural interfaces advance the possibilities for neuroscientists to study the brain. They are also promising for use in a multitude of bioelectronic therapies. Electrode technology plays a central role in these developments, as the electrode surfaces form the physical interfaces between technology and the biological targets. Despite this, a common understanding of how electrodes should best be evaluated and compared with respect to their efficiency in recording and stimulation is currently lacking. Without broadly accepted performance tests, it is difficult to rank the many suggestions for electrode materials available in the literature, or to identify where efforts should be focused to advance the field most efficiently. This tutorial critically discusses the most relevant performance tests for characterization of neural interface electrodes and explains their implementation, interpretation and respective limitations. We propose a unified standard to facilitate transparent reporting on electrode performance, promote efficient scientific process and ultimately accelerate translation into clinical practice.
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| 44. |
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| 45. |
- Buchmann, Sebastian
(författare)
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Organic Electronics and Microphysiological Systems to Interface, Monitor, and Model Biology
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biological processes in the human body are regulated through complex and precise arrangements of cell structures and their interactions. In vivo models serve as the most accurate choice for biological studies to understand these processes. However, they are costly, time-consuming, and raise ethical issues. Microphysiological systems have been developed to create advanced in vitro models that mimic in vivo-like microenvironments. They are often combined with integrated sensing technologies to perform real-time measurements to gain additional information. However, conventional sensing electrodes, made of inorganic materials such as gold or platinum, differ fundamentally from biological materials. Organic bioelectronic devices made from conjugated polymers are promising alternatives for biological sensing applications and aim to improve the interconnection between abiotic electronics and biotic materials. The widespread use of these devices is partly hindered by the limited availability of materials and low-cost fabrication methods. In this thesis, we provide new tools and materials that facilitate the use of organic bioelectronic devices for in vitro sensing applications. We developed a method to pattern the conducting polymer poly(3,4‑ethylenedioxythiophene) polystyrene sulfonate and to fabricate organic microelectronic devices using wax printing, filtering, and tape transfer. The method is low-cost, time-effective, and compatible with in vitro cell culture models. To achieve higher resolution, we further developed a patterning method using femtosecond laser ablation to fabricate organic electronic devices such as complementary inverters or biosensors. The method is maskless and independent of the type of conjugated polymer. Besides fabrication processes, we introduced a newly synthesized material, the semiconducting conjugated polymer p(g42T‑T)‑8%OH. This polymer contains hydroxylated side chains that enable surface modifications, allowing control of cell adhesion. Using the new femtosecond laser-based patterning method, we could fabricate p(g42T‑T)‑8%OH‑based organic electrochemical transistors to monitor cell barrier formations in vitro. Microphysological systems are further dependent on precise compartmentalization to study cellular interaction. We used femtosecond laser 3D printing to develop a co-culture neurite guidance platform to control placement and interactions between different types of brain cells. In summary, the thesis provides new tools to facilitate the fabrication of organic electronic devices and microphysiological systems. This increases their accessibility and widespread use to interface, monitor, and model biological systems.
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| 46. |
- Börjesson, Maria, 1974-, et al.
(författare)
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Optimal kilometre tax for electric vehicles
- 2023
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Ingår i: Transport Policy. - : Elsevier BV. - 0967-070X .- 1879-310X. ; 134, s. 52-64
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Tidskriftsartikel (refereegranskat)abstract
- We approximate the spatial and temporal distribution of the Pigouvian kilometre tax for road traffic in the most urbanized part of Sweden, with four million inhabitants and a similar "degree of urbanization" to the Netherlands and the UK, in a future scenario where most vehicles are electric. We apply the national transport model and include all links and four time-of-day periods. We find that roughly half of the vehicle kilometres travelled in Ma center dot lardalen has a marginal external cost (congestion and other external costs included) below 0.04 euro/km which is below the fuel tax in 2019). The mean marginal external cost is higher, at 0.09 euro/km. Our focus is not the exact numbers but the magnitudes and the vast variation across links in a country-like region: 90 percent of the revenue is collected on 10 percent of the road network. Hence, a nation-wide kilometre tax, implying high enforcement cost, is likely not the best option. Instead, the marginal external cost could probably be internalized fairly accurate by a congestion tax in the big cities in combination with for instance an ownership tax. We find that the Pigouvian tax would cover the public costs for our target road system. We relate our findings to the mainstem fiscal tax literature.
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| 47. |
- Chen, Xing, et al.
(författare)
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Chronic stability of a neuroprosthesis comprising multiple adjacent Utah arrays in monkeys
- 2023
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Ingår i: Journal of Neural Engineering. - 1741-2560 .- 1741-2552. ; 20:3
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Electrical stimulation of visual cortex via a neuroprosthesis induces the perception of dots of light ('phosphenes'), potentially allowing recognition of simple shapes even after decades of blindness. However, restoration of functional vision requires large numbers of electrodes, and chronic, clinical implantation of intracortical electrodes in the visual cortex has only been achieved using devices of up to 96 channels. We evaluated the efficacy and stability of a 1024-channel neuroprosthesis system in non-human primates (NHPs) over more than 3 years to assess its suitability for long-term vision restoration. Approach. We implanted 16 microelectrode arrays (Utah arrays) consisting of 8 x 8 electrodes with iridium oxide tips in the primary visual cortex (V1) and visual area 4 (V4) of two sighted macaques. We monitored the animals' health and measured electrode impedances and neuronal signal quality by calculating signal-to-noise ratios of visually driven neuronal activity, peak-to-peak voltages of the waveforms of action potentials, and the number of channels with high-amplitude signals. We delivered cortical microstimulation and determined the minimum current that could be perceived, monitoring the number of channels that successfully yielded phosphenes. We also examined the influence of the implant on a visual task after 2-3 years of implantation and determined the integrity of the brain tissue with a histological analysis 3-3.5 years post-implantation. Main results. The monkeys remained healthy throughout the implantation period and the device retained its mechanical integrity and electrical conductivity. However, we observed decreasing signal quality with time, declining numbers of phosphene-evoking electrodes, decreases in electrode impedances, and impaired performance on a visual task at visual field locations corresponding to implanted cortical regions. Current thresholds increased with time in one of the two animals. The histological analysis revealed encapsulation of arrays and cortical degeneration. Scanning electron microscopy on one array revealed degradation of IrOx coating and higher impedances for electrodes with broken tips. Significance. Long-term implantation of a high-channel-count device in NHP visual cortex was accompanied by deformation of cortical tissue and decreased stimulation efficacy and signal quality over time. We conclude that improvements in device biocompatibility and/or refinement of implantation techniques are needed before future clinical use is feasible.
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| 48. |
- Christleib, Norbert, et al.
(författare)
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4MOST Consortium Survey 2: The Milky Way Halo High-Resolution Survey
- 2019
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Ingår i: Messenger. - 0722-6691. ; 175, s. 26-29
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We will study the formation history of the Milky Way, and the earliest phases of its chemical enrichment, with a sample of more than 1.5 million stars at high galactic latitude. Elemental abundances of up to 20 elements with a precision of better than 0.2 dex will be derived for these stars. The sample will include members of kinematically coherent substructures, which we will associate with their possible birthplaces by means of their abundance signatures and kinematics, allowing us to test models of galaxy formation. Our target catalogue is also expected to contain 30 000 stars at a metallicity of less than one hundredth that of the Sun. This sample will therefore be almost a factor of 100 larger than currently existing samples of metal-poor stars for which precise elemental abundances are available (determined from high-resolution spectroscopy), enabling us to study the early chemical evolution of the Milky Way in unprecedented detail.
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| 49. |
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| 50. |
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