| 1. |
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| 2. |
- Andersson, Martin
(författare)
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Churning losses and efficiency in gearboxes
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Efficient transmissions systems are key to producing competitive motor vehicles that have a smaller environmental impact. Gears are the main components in vehicle transmissions and although they are already highly efficient, there is still room for improvement. In this study, the focus falls on the lubricant used to create separating films between gears and todissipate heat. When driving, the gears churn this lubricant, giving rise to power losses that are related to the amount and properties of the lubricant. However, any attempt to reduce these losses must not compromise the required lubrication and heat dissipation. Paper A reports on the use of an FZG gear test rig to investigate power losses and heat generation for different gear immersion depths, surface roughness and coatings. The results show that lower gear roughness reduces gear mesh losses and heat generation. A polishing affect was obtained when a non-coated gear ran against a coated gear.The aim of the research reported in paper B was to increase the accuracy of efficiency testing. It investigated how and whether repeated disassembly and re-assembly of the same test equipment, as well as test performance and rig conditions, affect the measured torque loss in an FZG gear test rig. It was shown that the measured torque loss changes between one assembly and another. Repeatability between tests is crucial for accurate conclusions.The aim of the research reported in paper C was to study whether gear efficiency could be increased by a running-in procedure, which would reduce the need for a coolant. A back-to-back gear test rig was used to test two running-in loads. Higher gear mesh efficiency was seen when a higher running-in load was used.
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| 3. |
- Andersson, Staffan, et al.
(författare)
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24-hour electrocardiographic study in myotonic dystrophy
- 1988
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Ingår i: Cardiology. - : S. Karger AG. - 0008-6312 .- 1421-9751. ; 75:4, s. 241-249
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-eight consecutive adult patients with myotonic dystrophy were included in a study with electrocardiography at rest and 24-hour ambulatory electrocardiography. The patients were subdivided into three groups according to the severity of the disease. The prevalence of abnormal electrocardiograms at rest was 31, 50 and 100% in patients with mild, moderate and severe disease, respectively. The main characteristics observed at ambulatory electrocardiography were a high frequency of sinus bradycardia (58%) and intermittent atrioventricular block II (8%). These bradyarrhythmias were not correlated to the severity of the disease. Sustained atrial fibrillation or flutter was found in 3 patients (8%), all with the most severe form of the disease. Ambulatory electrocardiography should be used deliberately in the evaluation of patients with myotonic dystrophy and symptoms compatible with cardiac arrhythmias.
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| 4. |
- Andersson, Staffan, et al.
(författare)
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Assessment of autonomic nerve function in myotonic dystrophy
- 1990
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Ingår i: Journal of the Autonomic Nervous System. - : Elsevier BV. - 0165-1838 .- 1872-7476. ; 29:3, s. 187-192
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Tidskriftsartikel (refereegranskat)abstract
- The function of the autonomic nervous system was studied in 23 patients with myotonic dystrophy, from a defined population in northern Sweden with an extremely high prevalence of this disease. Heart rate variability tests showed only minor signs of parasympathetic dysfunction. Blood pressure and plasma noradrenaline measurements in recumbent and upright positions showed no signs of sympathetic neuropathy. Increased plasma levels of noradrenaline was an unexpected finding. Our study does not support the hypothesis that cardiac arrhythmias, orthostatic hypotension, gastrointestinal motility disturbances and urinary bladder dysfunction in myotonic dystrophy are caused by autonomic neuropathy, and we believe that these symptoms should rather be ascribed to a defective function of the target organs
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| 5. |
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| 6. |
- Andsberg, Gunnar, et al.
(författare)
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PreHospital Ambulance Stroke Test : pilot study of a novel stroke test
- 2017
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - London, UK : BioMed Central. - 1757-7241. ; 25:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: There is a need for a prehospital stroke test that in addition to high sensitivity for stroke, also is able to communicate stroke severity similar to the National Institute of Health Stroke Scale (NIHSS).METHODS: The PreHospital Ambulance Stroke Test (PreHAST), an eight item test based on NIHSS, which scores stroke severity from 0-19 points, was designed and adapted for the ambulance services. In the pilot study the ambulance nurses used PreHAST to assess patients with suspected stroke in the prehospital setting. Regardless of the results after PreHAST testing the patients were triaged with a provisional stroke diagnosis. The PreHAST scores were compared with the final diagnosis and the ability to differentiate stroke and transient ischemic attacks (TIA) with ongoing symptoms at evaluation from non-stroke patients was analysed.RESULTS: 69 patients were included in the study, 26 had stroke/TIA and 43 other diagnoses. All stroke/TIA patients were identified by PreHAST (sensitivity 100% (95% CI; 87-100%)). The specificity increased with higher PreHAST scores and the discriminative capacity for PreHAST for different cut off values showed an area under the curve of 0.77 (95%CI; 0.66-0.88) in the receiver operating characteristic (ROC) analysis.DISCUSSION: PreHAST is designed for high sensitivity, screening for a broad range of stroke symptoms including most key components of NIHSS. The promising sensitivity between 87 and 100% in our study has to be confirmed in a larger study also including multiple centres. Higher PreHAST scores implied more typical patterns of stroke and accordingly the proportion of stroke mimics decrease with higher scores. However, also stroke mimics with epilepsy/seizure and patients with deficit after prior stroke could show higher PreHAST scores. Other prehospital stroke tests that evaluate stroke severity have been designed with the main purpose to screen for large vessel occlusion. The advantage of PreHAST is the dual purpose not only to evaluate stroke severity but also to screen for stroke in general.CONCLUSIONS: PreHAST is a new screening test of stroke adapted for ambulance services that in addition to high sensitivity for stroke, provides a grading system with increasing specificity with higher scores.
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| 7. |
- Augustsson, Anna, et al.
(författare)
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The risk of overestimating the risk-metal leaching to groundwater near contaminated glass waste deposits and exposure via drinking water
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 566, s. 1420-1431
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates metal contamination patterns and exposure to Sb, As, Ba, Cd and Pb via intake of drinking water in a region in southeastern Sweden where the production of artistic glass has resulted in a large number of contaminated sites. Despite high total concentrations of metals in soil and groundwater at the glassworks sites properties, all drinking water samples from households with private wells, located at a 30-640 m distance from a glassworks site, were below drinking water criteria from the WHO for Sb, As, Ba and Cd. A few drinking water samples showed concentrations of Pb above the WHO guideline, but As was the only element found in concentrations that could result in human exposure near toxicological reference values. An efficient retention of metals in the natural soil close to the source areas, which results in a moderate impact on local drinking water, is implied. Firstly, by the lack of significant difference in metal concentrations when comparing households located upstream and downstream of the main waste deposits, and secondly, by the lack of correlation between the metal concentration in drinking water and distance to the nearest glassworks site. However, elevated Pb and Cd concentrations in drinking water around glassworks sites when compared to regional groundwater indicate that diffuse contamination of the soils found outside the glassworks properties, and not only the glass waste landfills, may have a significant impact on groundwater quality. We further demonstrate that different mobilization patterns apply to different metals. Regarding the need to use reliable data to assess drinking water contamination and human exposure, we finally show that the conservative modelling approaches that are frequently used in routine risk assessments may result in exposure estimates many times higher than those based on measured concentrations in the drinking water that is actually being used for consumption. (C) 2016 Elsevier B.V. All rights reserved.
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| 8. |
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| 9. |
- Bergh, Gösta, et al.
(författare)
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Altered expression of the retinoblastoma tumor-suppressor gene in leukemic cell lines inhibits induction of differentiation but not G1-accumulation
- 1997
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Ingår i: Blood. - 1528-0020. ; 89:8, s. 2938-2950
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Tidskriftsartikel (refereegranskat)abstract
- The retinoblastoma tumor-suppressor gene, RB, has been implicated in tumor suppression, in regulation of the cell cycle, and in mediating cell differentiation. RB is necessary for hematopoiesis in mice, and aberrant RB-expression is associated with the progress and prognosis of leukemia. We have used antisense oligonucleotides, established clones stably expressing an antisense RB construct, and also established clones over expressing the retinoblastoma protein (pRb) to study the role of RB expression in monocytic differentiation induced by all-trans retinoic acid (ATRA) or 1-alpha-25-dihyroxycholecalciferol (Vit D3) in the monoblastic cell line U-937 and erythroid differentiation induced by transforming growth factor beta1 (TGFbeta1) and hemin in the erythroleukemic cell line K562. A reduction in pRb production in antisense RB-transfected U-937 clones was shown. Antisense oligonucleotides as well as expression of the antisense RB construct suppressed differentiation responses to ATRA or Vit D3, as judged by the capability to reduce nitro blue tetrazolium, by the appearance of monocyte-related cell surface antigens and by morphologic criteria. K562 cells showed decreased differentiation response to TGFbeta1, but not to hemin, when incubated with antisense oligonucleotides. U-937 antisense RB-transfected cells were also suppressed in their ability to upregulate levels of hypophosphorylated pRb when induced to differentiate. Although U-937 cells incubated with antisense oligonucleotides and clones expressing the antisense RB construct were hampered in their ability to differentiate on incubation with ATRA or Vit D3, the induced G0/G1-accumulation was similar to differentiating control cells treated with ATRA or Vit D3. Intriguingly, U-937 clones overexpressing RB were also inhibited in their differentiation response to ATRA or Vit D3 but not inhibited in their ability to respond with G0/G1 accumulation when induced with these substances. The results indicate that pRb plays a role in induced differentiation of U-937 cells as well as K562 cells involving mechanisms that, at least partially, are distinct from those inducing G1 accumulation.
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| 10. |
- Berntorp, Karl, et al.
(författare)
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Models and Methodology for Optimal Vehicle Maneuvers Applied to a Hairpin Turn
- 2013
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Ingår i: 2013 American Control Conference. - 0743-1619. - 9781479901777 ; , s. 2139-2146
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Konferensbidrag (refereegranskat)abstract
- There is currently a strongly growing interest in obtaining optimal control solutions for vehicle maneuvers, both in order to understand optimal vehicle behavior and to devise improved safety systems, either by direct deployment of the solutions or by including mimicked driving techniques of professional drivers. However, it is nontrivial to find the right mix of models, formulations, and optimization tools to get useful results for the above purposes. Here, a platform is developed based on a state-of-the-art optimization tool together with adoption of existing vehicle models, where especially the tire models are in focus. A minimum-time formulation is chosen to the purpose of gaining insight in at-the-limit maneuvers, with the overall aim of possibly finding improved principles for future active safety systems. We present optimal maneuvers for different tire models with a common vehicle motion model, and the results are analyzed and discussed. Our main result is that a few-state single-track model combined with different tire models is able to replicate the behavior of experienced drivers. Further, we show that the different tire models give quantitatively different behavior in the optimal control of the vehicle in the maneuver.
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| 11. |
- Bjerle, P, et al.
(författare)
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Electrocardiographic findings in myotonic dystrophy
- 1988
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Ingår i: British Heart Journal. - : BMJ. - 0007-0769. ; 59:1, s. 47-52
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Tidskriftsartikel (refereegranskat)abstract
- Sixty five patients with myotonic dystrophy, from a defined population in northern Sweden with an extremely high prevalence of this disease, were examined by electrocardiography. The patients were subdivided into three groups according to the severity of the disease. Abnormal electrocardiograms were found in 6 (35%) patients with mild disease, 12 (50%) patients with moderate disease, and 23 (96%) patients with severe disease. First degree atrioventricular block and left anterior hemiblock were the most commonly encountered abnormalities in patients with mild and moderate disease, whereas atrial fibrillation and flutter, abnormal Q waves, and repolarisation abnormalities were more common in patients with severe disease. This study shows that the heart is often affected by myotonic dystrophy. These effects can be detected by electrocardiography in early and mild forms of the disease. The effect on the heart is progressive and clinically important atrial arrhythmias and electrocardiographic abnormalities which are useful in differential diagnosis are common in severe forms of the disease.
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| 12. |
- Björk, Folke, 1958-, et al.
(författare)
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Dränering av fukt i betong genom elektrokemisk metodik (elektroosmos)
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med detta projekt är att studera funktionen av elektroosmos som åtgärd mot fukt-problem i byggnader i Sverige samt att utifrån detta ge rekommendationer kring om och i så fall när det är lämpligt/olämpligt att använda metodiken under de varierande fuktighets-förhållanden som vanligtvis råder i Sverige.I projektet har vi gjort en litteraturstudie, en modellering av fysikaliska processer, studie-besök i byggnader med installationer för elektroosmos och mätningar av fukt i en källarvägg där en installation för elektroosmos blivit gjord.Vi ser metoden elektroosmos som en möjlighet för att hantera fuktproblem i grunder. Det behövs dock en del av utveckling både kring tekniken för metoden och kring vad som ska kunna förväntas av den.Det behövs bättre möjligheter att kunna förutsäga att metoden kommer att fungera i ett visst fall. Att inte kunna förutsäga detta bör vara ett bekymmer för dem som marknadsför metoden.Elektroosmos kräver höga fuktnivåer för att fungera. Torkning ned till under kritiska fuktnivåer kräver komplettering med andra torkmetoder. Det krävs en tydlighet kring hur detta ska lösas.Det behövs en bättre förståelse kring hur elektroderna ska placeras för bästa funktion.Fuktvandring i jorden kan ha stor betydelse för processen i praktiken. Det är idé att undersöka om detta kan användas för att utveckla metoden.Det behövs klara regler kring hur elinstallationen ska utformas på ett säkert sätt.Eftersom jontransporten i betongen är av ganska liten omfattning så tror vi inte att elektroosmos kommer att påverka, eller skada, betongens egenskaper på lång sikt.
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| 13. |
- Björk, Folke, et al.
(författare)
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Electroosmosis - A method applied for handling of moisture in foundations
- 2020
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Ingår i: E3S Web of Conferences. Volyme 172, 2020. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- Electroosmosis is an electrokinetic phenomena which is applied in some technical fields. It is also applied large scale for transport of moisture out of basements. We see the method of electroosmosis as an opportunity for solving moisture problems in basements. However, there is a need to develop both the technology for the method and the understanding about what to expect out of it. Better methods are needed to predict whether the method will work in a particular case. © The Authors.
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| 14. |
- Björkman, Anne, 1981, et al.
(författare)
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Plant functional trait change across a warming tundra biome
- 2018
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 562:7725, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature–trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming.
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| 15. |
- Björkman, Anne, 1981, et al.
(författare)
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Tundra Trait Team: A database of plant traits spanning the tundra biome
- 2018
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 27:12, s. 1402-1411
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 The Authors Global Ecology and Biogeography Published by John Wiley & Sons Ltd Motivation: The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained: The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (>1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain: Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain: All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement: Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format: csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release.
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| 16. |
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| 17. |
- Borg, Sixten, et al.
(författare)
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Patient-reported outcome and experience measures for diabetes: development of scale models, differences between patient groups and relationships with cardiovascular and diabetes complication risk factors, in a combined registry and survey study in Sweden
- 2018
-
Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 9:1
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose The Swedish National Diabetes Register (NDR) has developed a diabetes-specific questionnaire to collect information on individuals' management of their diabetes, collaboration with healthcare providers and the disease’s impact on daily life. Our main objective was to develop measures of well-being, abilities to manage diabetes and judgements of diabetes care, and to detect and quantify differences using the NDR questionnaire.Design, setting and participants The questionnaire was analysed with using responses from 3689 participants with type 1 and 2 diabetes, randomly sampled from the NDR population, combined with register data on patient characteristics and cardiovascular and diabetes complication risk factors.Methods We used item response theory to develop scales for measuring well-being, abilities to manage diabetes and judgements of diabetes care (scores). Test–retest reliability on the scale level was analysed with intraclass correlation. Associations between scores and risk factor levels were investigated with subgroup analyses and correlations.Results We obtained scales with satisfactory measurement properties, covering patient reported outcome measures such as general well-being and being free of worries, and patient reported experience measure, for example, access and continuity in diabetes care. All scales had acceptable test–retest reliability and could detect differences between diabetes types, age, gender and treatment subgroups. In several aspects, for example, freedom of worries, type 1 patients report lower than type 2, and younger patients lower than older. Associations were found between some scores and glycated haemoglobin, but none with systolic blood pressure or low-density lipoprotein cholesterol. Clinicians report positive experience of using scores, visually presented, in the patient dialogue.Conclusions The questionnaire measures and detects differences in patient well-being, abilities and judgements of diabetes care, and identifies areas for improvement. To further improve diabetes care, we conclude that patient-reported measures are important supplements to cardiovascular and diabetes complication risk factors, reflecting patient experiences of living with diabetes and diabetes care.
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| 18. |
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| 19. |
- Brämerson, Annika, 1960, et al.
(författare)
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Event-related potentials in patients with olfactory loss.
- 2008
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Ingår i: Acta oto-laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 128:10, s. 1126-31
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Tidskriftsartikel (refereegranskat)abstract
- CONCLUSION: The olfactory event-related potential (OERP) method provides a means of objectively assessing olfactory function. However, further validation is needed before OERPs can be routinely applied in clinical assessment of olfactory dysfunction. OBJECTIVE: To assess OERPs in patients with olfactory impairment and in healthy controls to investigate possible dose-response effects of odor concentration on OERP parameters in these groups, thereby exploring possibilities and limitations regarding the clinical utility of the OERP method. SUBJECTS AND METHODS: Twenty-three patients with a history of impaired olfactory function and 24 controls participated in the study. Olfactory function was assessed with psychophysical tests, i.e. assessment of the odor threshold, and odor identification. OERPs were obtained in response to the olfactory stimulant butanol at two different concentrations, presented via an olfactometer. RESULTS: The OERP amplitudes increased and the latencies shortened with increasing stimulus concentration. Furthermore, a difference between the groups was found, with higher OERP amplitudes and shorter latencies in healthy subjects compared with patients.
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| 20. |
- Butler, Éile, et al.
(författare)
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A pilot study investigating lactic acid bacterial symbionts from the honeybee in inhibiting human chronic wound pathogens
- 2016
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Ingår i: International Wound Journal. - Oxford : Blackwell Publishing. - 1742-4801 .- 1742-481X. ; 13:5, s. 729-37
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Tidskriftsartikel (refereegranskat)abstract
- Treatment and management of chronic wounds is a large burden on the health sector and causes substantial suffering for the patients. We believe that 13 lactic acid bacteria (LAB) symbionts isolated from the honey crop of the honeybee are important players in the antimicrobial action of honey, by producing antimicrobial substances and can be used in combination with heather honey as an effective treatment in wound management. A total of 22 patients with chronic ulcers were included; culture-dependent and molecular-based (MALDI-MS and 16S rRNA gene sequencing) techniques were used to identify bacteria from chronic wounds. These clinical isolates were used for in vitro antimicrobial testing with standardised viable LAB and sterilised heather honey mixture. Twenty of the patients' wounds were polymicrobial and 42 different species were isolated. Patient isolates that were tested in vitro were inhibited by the LAB and honey combination with inhibitory zones comparable with different antibiotics. LAB and heather honey in combination presents a new topical option in chronic wound management because of the healing properties of honey, antimicrobial metabolite production from the LAB and their bactericidal effect on common chronic wound pathogens. This new treatment may be a stepping stone towards an alternative solution to antibiotics.
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| 21. |
- Carlsson, Bo, et al.
(författare)
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The Evolving Domain of Entrepreneurship Research
- 2012
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Ingår i: International Schumpeter Society conference, Brisbane, Australia, June 2012.
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Konferensbidrag (refereegranskat)abstract
- Research on entrepreneurship has flourished in recent years and is evolving rapidly. This paper explores the history of entrepreneurship research, how the research domain has evolved, and its current status as an academic field. An overview is provided of where the field stands today and how it is positioned relative to the existing disciplines and new research fields, upon which it draws. Areas needed for future progress are highlighted, particularly the need for an evolutionary theory of entrepreneurship that relates entrepreneurial activity to economic growth and human welfare.
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| 22. |
- Carlsson, Bo, et al.
(författare)
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The evolving domain of entrepreneurship research
- 2013
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Ingår i: Small Business Economics. - : Springer Science and Business Media LLC. - 0921-898X .- 1573-0913. ; 41:4, s. 913-930
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Tidskriftsartikel (refereegranskat)abstract
- Research on entrepreneurship has flourished in recent years and is evolving rapidly. This article explores the history of entrepreneurship research, how the research domain has evolved, and its current status as an academic field. The need to concretize these issues stems partly from a general interest in defining the current research domain and partly from the more specific tasks confronting the prize committee of the Global Award for Entrepreneurship Research. Entrepreneurship has developed in many sub-fields within several disciplines-primarily economics, management/business administration, sociology, psychology, economic and cultural anthropology, business history, strategy, marketing, finance, and geography-representing a variety of research traditions, perspectives, and methods. We present an analytical framework that organizes our thinking about the domain of entrepreneurship research by specifying elements, levels of analysis, and the process/context. An overview is provided of where the field stands today and how it is positioned relative to the existing disciplines and new research fields upon which it draws. Areas needed for future progress are highlighted, particularly the need for a rigorous dynamic theory of entrepreneurship that relates entrepreneurial activity to economic growth and human welfare. Moreover, applied work based on more careful design as well as on theoretical models yielding more credible and robust estimates seems also highly warranted.
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| 23. |
- Cesano, Daniele, et al.
(författare)
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Parameters regulating groundwater inflows into hard rock tunnels - a statistical study of the Bolmen tunnel in southern Sweden
- 2000
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Ingår i: Tunnelling and Underground Space Technology. - 0886-7798 .- 1878-4364. ; 15:2, s. 153-165
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Tidskriftsartikel (refereegranskat)abstract
- Inflow of groundwater into tunnels has always been a major technical and environmental problem for underground constructions. Predictions of groundwater inflow using analytical and numerical tools have often failed due to generalization and simplification of important parameters, especially in heterogeneous media such as crystalline rocks. In order to identify those parameters that regulate inflows, a systematic statistical analysis has been carried out at a tunnel constructed in the hard crystalline rocks of southern Sweden. The parameters included topographically, technically and geologically important variables in the hard crystalline rocks as well as in the overburden. The study revealed that many factors related to the rock quality, as well as to the overburden-such as the number of fractures, the thickness of the overburden, the soil type and the amount of pregrouting-regulated the leakage. It seems that a clear difference exists between the parameters that regulate the major and the minor leakage. The minor leakage is associated more with the drainage of the rock mass, while the major leakage is clearly associated with different parameters in the overburden. Unless the overburden anal the rock mass are considered as an interrelated system, predictions of groundwater inflows are likely to fail.
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| 24. |
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| 25. |
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| 26. |
- Danfors, Torsten, et al.
(författare)
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Tetrahydrobiopterin in the treatment of children with autistic disorder. A double-blind placebo-controlled crossover study
- 2005
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Ingår i: Journal of Clinical Psychopharmacology. - 0271-0749 .- 1533-712X. ; 25:5, s. 485-489
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Tidskriftsartikel (refereegranskat)abstract
- Twelve children, all boys, aged 4 to 7 years, with a diagnosis of autistic disorder and low concentrations of spinal 6R-l-erythro-5,6,7,8-tetrahydrobiopterin (tetrahydrobiopterin) were selected to participate in a double-blind, randomized, placebo-controlled, crossover study. The children received a daily dose of 3 mg tetrahydrobiopterin per kilogram during 6 months alternating with placebo. Treatment-induced effects were assessed with the Childhood Autism Rating Scale every third month. The results showed small nonsignificant changes in the total scores of Childhood Autism Rating Scale after 3- and 6-month treatment. Post hoc analysis looking at the 3 core symptoms of autism, that is, social interaction, communication, and stereotyped behaviors, revealed a significant improvement of the social interaction score after 6 months of active treatment. In addition, a high positive correlation was found between response of the social interaction score and IQ. The results indicate a possible effect of tetrahydrobiopterin treatment.
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| 27. |
- Dehkordi, Seyed Emad, et al.
(författare)
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Effect of groundwater flow in vertical and horizontal fractures on borehole heat exchanger temperatures
- 2015
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Ingår i: Bulletin of Engineering Geology and the Environment. - : Springer Berlin/Heidelberg. - 1435-9529 .- 1435-9537. ; 74:2, s. 479-491
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Tidskriftsartikel (refereegranskat)abstract
- Vertical closed loop systems, also known as borehole heat exchangers (BHEs), are a popular way of extracting the ground source heat energy. Primary factors affecting the performance of BHEs are the thermal and hydrogeological properties of the subsurface. Groundwater flow is known to potentially influence heat transport and system performance. The effect of groundwater movement is more commonly studied under homogeneous conditions. However, in heterogeneous fractured rocks, BHEs are more common than horizontal or open loops due to lack of sufficient soil layers and productive aquifers. The finite-element modelling shows that fractures can play an important role in BHE functioning. Especially, vertical open fractures (≥1 mm) near the borehole (≤10 m) can have a considerable impact. Although increase in fracture aperture continuously affects the subsurface and BHE temperatures, the increase in its effect progressively lessens. Depending on the distance and aperture, one major fracture influencing the BHE operation performance can be identified; yet a larger number of fractures may govern heat transport (thermal plume outline) and thermal recovery. Individually, horizontal fractures may have less influence than vertical fractures. However, as the density of horizontal fractures increases, their impact can be major, exceeding that of fracture aperture. In particular, we propose that measurements of rock thermal properties be combined with fracture mapping, to better analyse the thermal response testing results and integrate the configuration of fractures in design and layout of the BHE(s). This is particularly valid for (vertical) fractures not intersecting with the borehole.
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| 28. |
- Dehkordi, Seyed Emad, et al.
(författare)
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Impact of Groundwater Flow and Energy Load on Multiple Borehole Heat Exchangers
- 2014
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Ingår i: Ground Water. - : John Wiley & Sons. - 0017-467X .- 1745-6584.
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Tidskriftsartikel (refereegranskat)abstract
- The effect of array configuration, that is, number, layout, and spacing, on the performance of multiple borehole heat exchangers (BHEs) is generally known under the assumption of fully conductive transport. The effect of groundwater flow on BHE performance is also well established, but most commonly for single BHEs. In multiple-BHE systems the effect of groundwater advection can be more complicated due to the induced thermal interference between the boreholes. To ascertain the influence of groundwater flow and borehole arrangement, this study investigates single- and multi-BHE systems of various configurations. Moreover, the influence of energy load balance is also examined. The results from corresponding cases with and without groundwater flow as well as balanced and unbalanced energy loads are cross-compared. The groundwater flux value, 10−7 m/s, is chosen based on the findings of previous studies on groundwater flow interaction with BHEs and thermal response tests. It is observed that multi-BHE systems with balanced loads are less sensitive to array configuration attributes and groundwater flow, in the long-term. Conversely, multi-BHE systems with unbalanced loads are influenced by borehole array configuration as well as groundwater flow; these effects become more pronounced with time, unlike when the load is balanced. Groundwater flow has more influence on stabilizing loop temperatures, compared to array characteristics. Although borehole thermal energy storage (BTES) systems have a balanced energy load function, preliminary investigation on their efficiency shows a negative impact by groundwater which is due to their dependency on high temperature gradients between the boreholes and surroundings.
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| 29. |
- Destouni, Georgia, et al.
(författare)
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Biogeochemical Transformation Pathways through the Land-water Geosphere
- 2014
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Konferensbidrag (refereegranskat)abstract
- Water on land undergoes and participates in many biogeochemical exchanges and changes. A bits-and-pieces approach to these may miss essential aspects of change propagation and transformation by land-water through different segments of the Earth system. This paper proposes a conceptualization of the entire land-water geosphere as a scale-free catchment-wise organised system (Figure 1), emphasizing four key new system aspects compared to traditional hydrosphere/water cycle view: i) distinction of coastal divergent in addition to traditional convergent catchments; ii) physical and social-ecological system coupling through four main nodal zones/interfaces (surface, subsurface, coastal, observation); iii) flow-transport pathways as system coupling agents; iv) multiple interactions with the anthroposphere as integral system parts. Utilizing this conceptualization, we identify distinct patterns of direct anthropogenic change in large-scale water and waterborne nutrient fluxes, emerging across different parts of the world. In general, its embedment directly in the anthroposphere/technosphere makes land-water a key geosphere for understanding and monitoring human-driven biogeochemical changes. Further progress in system-level understanding of such changes requires studies of land-water as a continuous yet structured geosphere following the proposed spatiotemporal pathways of change propagation-transformation.
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| 30. |
- Destouni, Georgia, 1961-, et al.
(författare)
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Needs and means to advance science, policy and management understanding of the freshwater system : A synthesis report
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fragmented and inconsistent understanding of the freshwater system limits our ability to achieve water security and sustainability under the human-driven changes occurring in the Anthropocene. To advance system-level understanding of freshwater, gaps and inconsistencies in knowledge, data, representations and links of processes and subsystems need to be identified and bridged under consideration of the freshwater system as a continuous whole. Based on such identification, a freshwater system conceptualization is developed in this report, which emphasizes four essential, yet often neglected system aspects:i) Distinction of coastal divergent catchments.ii) Four main zones (surface, subsurface, coastal, observation) of different types of freshwater change.iii) Water pathways as system-coupling agents that link and partition water change among the four change zones.iv) Direct interactions with the anthroposphere as integral system pathways across the change zones.We explain and exemplify some key implications of these aspects, identifying in the process also distinct patterns of human-driven changes in large-scale water fluxes and nutrient loads.The present conceptualization provides a basis for common inter- and trans-disciplinary understanding and systematic characterization of the freshwater system function and its changes, and of approaches to their modeling and monitoring. This can be viewed and used as a unifying checklist that can advance science, policy and management of freshwater and related environmental changes across various scales and world regions.
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| 31. |
- Earon, Robert, 1983-
(författare)
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Groundwater resources in hard rock coastal terrains : Insights into heterogeneity and spatial variability
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Challenges regarding water security in hard rock coastal regions with limited soil cover are: a seasonal absence of recharge during times of peak residency, heterogeneity and variability of the fracture network, close proximity to saline water sources and spatially inconsistent storage and extraction. In areas where it is not feasible to connect residents to municipal water systems, a better understanding of the resilience of reservoirs is needed. The purpose of this study is to investigate and describe the spatial nature of hydraulic data in these types of terrains and present several novel GIS-based groundwater tools with the intent of increasing local water security and aiding in sustainable water resources management. Methods used in this study include groundwater balance modelling and conceptual groundwater storage modelling, as well as a combination of parametric and non-parametric statistical methods such as ANOVA, PCA, correlation and semivariogram analyses. Specific capacity estimates from the Geological Survey of Sweden’s well archive grouped by age or rock type showed very little autocorrelation and in assumed homogeneous geological regions showed statistically significant differences when arbitrarily grouped along a lineament. Estimates of kinematic porosity based on surface fracture data were found have statistically significant correlations with the well data. A GIS-based multivariate prediction tool for assessing Groundwater Resources Potential (GRP) was found to have statistically significant correlations with well data. The GRP method was then combined with a conceptual groundwater storage model and was subsequently found to have statistically significant correlations with chloride concentrations in well quality tests. The storage model was found to have a spatially-dependent sensitivity, meaning that different assumptions within the model had varying effects on the model depending on the geological settings. Incorporating the storage model into a spatial groundwater balance model was then compared with groundwater level time series data over a period of two years, where it was found to have a good explanative capacity and RMSE values of the storage ratio (0.06 to 0.34). Additionally, a soil depth model was developed, tested and found to produce promising results in regions with frequent rock outcrops, where up to 86% of estimates were within 2 m of actual soil depths. Conclusions from this study illustrate the need for a spatial approach to groundwater resources in these types of terrains, and demonstrate a strong potential of several new tools for quantity, capacity and vulnerability estimates to increase water security in a changing climate.
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| 32. |
- Earon, Robert, et al.
(författare)
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Groundwater Resources Potential in Hard Rock Terrain : A Multivariate Approach
- 2014
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Ingår i: Ground Water. - : John Wiley & Sons. - 0017-467X .- 1745-6584.
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater resources are limited and difficult to predict in crystalline bedrock due to heterogeneity and anisotropy in rock fracture systems. Municipal-level governments often lack the resources for traditional hydrogeological tests when planning for sustainable use of water resources. A new methodology for assessing groundwater resources potential (GRP) based on geological and topographical factors using principal component analysis (PCA) and analysis of variance (ANOVA) was developed and tested. ANOVA results demonstrated statistically significant differences in classed variable groups as well as in classed GRP scores with regard to hydrogeological indicators, such as specific capacity (SC) and transmissivity. Results of PCA were used to govern the weight of the variables used in the prediction maps. GRP scores were able to identify 79% of wells in a verification dataset, which had SC values less than the total dataset median. GRP values showed statistically significant correlations using both parametric (using transformed datasets) and non-parametric methods. The method shows promise for municipal or regional level planning in crystalline terrains with high levels of heterogeneity and anisotropy as a hydrogeologically and statistically based tool to assist in assessing groundwater resources. The methodology is executed in a geographic information systems environment, and uses often readily available data, such as geological maps, feature maps and topography, and thus does not require expensive and time-consuming aquifer tests.
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| 33. |
- Earon, Robert, et al.
(författare)
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Hydraulic heterogeneity and its impact on kinematic porosity in Swedish coastal terrains
- 2018
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Ingår i: Engineering Geology. - : Elsevier. - 0013-7952 .- 1872-6917. ; 245
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogeology in crystalline rock aquifers is often problematic due to the heterogeneity and anisotropy in thefracture network. Kinematic porosity of the host rock is exceedingly important for municipal decision makers inassessing sustainably extractable water supply volumes and assessing contaminant transport behavior within thematrix. This study explores heteroscedasticity in the hydrogeological characteristics of the fracture network andestimation of kinematic porosity from superficial fracture measurements. Estimates were based on the geometricalproperties of the fractures including: fracture frequency, aperture and orientation. The estimates wereadjusted for aperture changes with depth, connectivity of the fracture network, fracture continuity and measurementorientation bias. The results were compared with well archive data and correlations were found to besignificant with more than 95% confidence. Erratic behaviour of well data relative to fracture measurementsindicates that well orientation with respect to the fracture network gives incomplete hydrogeological data.Spatial heterogeneity of the bedrock was examined using spatial statistics and geographic information systems.The results from the spatial statistical analyses of well data showed that the heterogeneity within the bedrock issufficiently high that spatial correlations cease to exist in nearly all investigated rock types at distances greaterthan 500 m, and in some rocks, particularly sedimentary gneisses, no spatial correlations were observed.Arbitrarily grouped samples with similar geology and topography showed evidence of non-stationary variance.Results indicate that regional generalizations based on sparse point measurements are highly error prone andpotential exists in complementary field-based estimates.
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| 34. |
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| 35. |
- Earon, Robert, et al.
(författare)
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Initial Effects of a New Highway Section on Soil and Groundwater
- 2012
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Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 223:8, s. 5413-5432
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Tidskriftsartikel (refereegranskat)abstract
- The environmental impacts of 16 different contaminants originating from the E18 Highway (17,510 annual average daily traffic) were studied over the initial months of the highway's operational life. Investigative methods used included electrical resistivity surveying, water chemistry analyses, soil analyses, distribution modeling, and transportation modeling of contaminants. The study conclusively showed a year-round infiltration due to melting of the snowpack from road salt, and a strong preferential, anthropogenic pathway due to increased hydraulic conductivities of road construction materials relative to in situ soils. The resistivity surveys produced values well below the expected values for the highway materials, indicating increased ionic content within the unsaturated zone. Time lapse resistivity modeling showed a clear downwards spreading of contamination from the roadway to subsurface distances greater than 5 m. Elevated concentrations of nearly every studied contaminant relative to baseline values were observed, with many metal concentrations within the snow pack averaging values in excess of the Swedish Environmental Protection Agency's groundwater limitations. Distribution modeling demonstrated a potential offset of peak values from the road surface due to plowing and splash transport processes, and indicated different distribution behavior during winter months than during summer months. One-dimensional transport modeling demonstrated the importance of adsorption and other retentive factors to the migration of contaminants to groundwater and provided an estimate for potential long-term contaminant concentrations.
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| 36. |
- Earon, Robert, et al.
(författare)
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Insight into the influence of local streambed heterogeneity on hyporheic-zone flow characteristics
- 2020
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Ingår i: Hydrogeology Journal. - : Springer Science and Business Media Deutschland GmbH. - 1431-2174 .- 1435-0157. ; 28:8, s. 2697-2712
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Tidskriftsartikel (refereegranskat)abstract
- Interaction between surface water and groundwater plays a fundamental role in influencing aquatic chemistry, where hyporheic exchange processes, distribution of flow paths and residence times within the hyporheic zone will influence the transport of mass and energy in the surface-water/groundwater system. Geomorphological conditions greatly influence hyporheic exchange, and heterogeneities such as rocks and clay lenses will be a key factor for delineating the hyporheic zone. Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) were used to investigate the streambed along a 6.3-m-long reach in order to characterise geological layering and distinct features which may influence parameters such as hydraulic conductivity. Time-lapse ERT measurements taken during a tracer injection demonstrated that geological features at the meter-scale played a determining role for the hyporheic flow field. The penetration depth of the tracer into the streambed sediment displayed a variable spatial pattern in areas where the presence of highly resistive anomalies was detected. In areas with more homogeneous sediments, the penetration depth was much more uniformly distributed than observed in more heterogeneous sections, demonstrating that ERT can play a vital role in identifying critical hydraulic features that may influence hyporheic exchange processes. Reciprocal ERT measurements linked variability and thus uncertainty in the modelled resistivity to the spatial locations, which also demonstrated larger variability in the tracer penetration depth, likely due to local heterogeneity in the hydraulic conductivity field.
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| 37. |
- Earon, Robert, et al.
(författare)
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Integrating storage and spatial variability into regional groundwater balances : Moving towards water security in hard rock coastal areas
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In terrains with limited soil cover and groundwater storage, groundwater resource management is governed by the spatial nature of storage, recharge and extraction. Local soils may act as important groundwater reservoirs for residents which have no other feasible water supply. A novel groundwater balance methodology is presented which accounts for the spatial distribution of storage and extraction. Existing topographical and geological databases as well as well data were used to construct a conceptual model of the groundwater system, assuming stratigraphy based on typical geology. The method is implemented in a geographic information systems environment and allows for variable climate and land use scenarios.Several scenarios were examined with this method, demonstrating that on a regional scale average reservoir volumes meet demand but at the local levels depletion of reservoirs may be experienced. Groundwater level drawdown in excess of 50% of the projected reservoir storage were seen, particularly near the coast. Soil-filled valleys may act as local hydraulic barriers, preventing contamination from saline water provided no direct hydraulic connection is present. The method demonstrates the importance of a spatial approach in managing groundwater resources, and shows promise as a tool for planners in increasing water security.
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| 38. |
- Earon, Robert, et al.
(författare)
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Integrating storage and spatial variability into shallow groundwater balances : moving towards water security in hard rock coastal areas
- 2020
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Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694. ; 51:6, s. 1293-1311
-
Tidskriftsartikel (refereegranskat)abstract
- In terrains with limited soil cover and groundwater storage, groundwater resource management is governed by the spatial nature of storage, recharge and distributed local extraction. Local soils act as important groundwater reservoirs for residents who have no other feasible water supply. A novel heuristic methodology is presented which accounts for the spatial distribution of storage and extraction, using existing topographical and geological databases in addition to well data to construct an applied conceptual groundwater model with assumed stratigraphy. The method uses a geographic information systems (GIS) environment and allows for modelling climate and land-use scenarios. Several scenarios were examined, demonstrating that average reservoir volumes meet demand but at the local levels depletion of reservoirs occurs. Groundwater abstraction in excess of 50% of the approximate freshwater storage was observed in the model, particularly near the coast. Soil-filled valleys may act as local hydraulic barriers by maintaining a higher pressure head as they are less susceptible to large-level fluctuations than the hard rock and may aid in preventing contamination from saline water provided no direct hydraulic connection is present. The method demonstrates the importance of a spatial approach in managing groundwater resources and could be used as a tool in increasing water security.
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| 39. |
- Earon, Robert, et al.
(författare)
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The importance of a spatial approach to water resources management in heterogeneous regions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Limited groundwater storage in recently glaciated terrains with frequent hard, crystalline bedrock outcrops poses challenges for groundwater resources management. Due to often-limited economic resources allocated to groundwater investigations in areas where drinking water is primarily supplied by private wells, heuristic solutions such as groundwater balances with built-in limitations of storage may serve a vital role in improving water security. This study investigates the use of a conceptual groundwater balance model and the use of a conceptual-statistical reservoir vulnerability model with this aim. A limited storage, GIS-based groundwater balance model using existing databases was applied to an area outside of Stockholm, Sweden with existing groundwater level measurement data. The spatial model showed improved performance over existing S-Hype model estimates of groundwater levels currently used in groundwater resources management by the Geological Survey of Sweden, even without local calibration. Differences between two wells with time series data showed evidence of strong influence due to in-situ geological conditions. Groundwater vulnerability estimates correlated significantly with chloride measurements from an existing chemistry database. The performance of the conceptually-based spatial groundwater balance supports the use of the approach as an aid for municipal planners and decision-makers in moving towards sustainable groundwater resources planning and improving water security in areas with limited storage and a large number of dispersed, private wells.
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| 40. |
- Earon, Robert
(författare)
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Water supply in hard rock coastal regions : The effect of heterogeneity and kinematic porosity
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Water resources in hard rock terrain are difficult to characterize due to heterogeneity and anisotropy in the fracture network, low porosities and limited recharge volumes available during the summer season. Three methods were developed and evaluated in order to assist in water supply planning. A groundwater resources potential index was estimated using multivariate statistics, where physical and geological variables were classified using Analysis of Variance and Fisher's Least Significant Difference tests according to their effect on hydraulic properties. Principal component analysis was used to assign weights to the different classed variables. Classes and weights were used to produce an index referred to as groundwater resources potential (GRP), which correlated significantly with well data. Nearly 80% of the wells with less than median specific capacity values also had GRP values at those locations of zero or lower. Non-stationary variance was observed in specific capacity sub-samples taken from the Geological Survey of Sweden's well archive, despite homogeneous geology and topography. Spatial statistical analyses showed that spatial correlations were weak in well archive samples, implying that regional approximations based on sparse point data are highly error prone. Kinematic porosity estimated using superficial fracture measurements correlated significantly with well archive data. However, low correlation coefficients indicated that well data is likely not a suitable method for predicting water supply characteristics. This approach is an efficient method which shows promise in preliminary estimations of groundwater storage in heterogenic terrains. A groundwater balance model which describes seasonal groundwater storage changes was created in order to better approximate the groundwater situation often found in Swedish urbanized and semi-urbanized hard rock terrains. The model was based on a water budget approach at the pixel scale, and allows for approximation of well extraction which is not uniformly distributed in space. The model showed that in specific regions groundwater extraction may lead to severe decreases in groundwater level, where these impacts may not otherwise be expected. Dry season modelling with 10% increased evapotranspiration showed that in several areas groundwater reservoir depletion may be influenced by more than 50%.
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| 41. |
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| 42. |
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| 43. |
- Eeg-Olofsson, Måns, 1967, et al.
(författare)
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BCI-bone conduction implant.
- 2013
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Ingår i: The Fourth International Symposium on Bone Conduction Hearing – Craniofacial Osseointegration. Newcastle, UK.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 44. |
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Eeg-Olofsson, Måns, 1967, et al.
(författare)
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Evaluation of bone tissue formation in a flat surface attachment of a Bone Conduction Implant - A pilot study in a sheep model
- 2014
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Ingår i: Audiology & Neurotology Extra. - : S. Karger AG. - 1664-5537. ; 4:3, s. 62-76
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Tidskriftsartikel (refereegranskat)abstract
- The Bone Conduction Implant (BCI) is a new bone conduction hearing device implanted under intact skin. The transducer has a flat direct contact to the mastoid part of the temporal bone and no screws are used. The sound signal is transmitted from the external audio processor to the implant by means of magnetic induction. In this study, osseointegration of a flat passive BCI transducer dummy in sheep skulls was assessed using quantitative and qualitative histology as well as Cone Beam Computed Tomography (CBCT) and Computed Tomography (CT). The histology results were also related to the mechanical properties of the bone to implant interface. Eight months after the surgical implantation, histology sections of the bone close to the implant showed bone remodelling, compact bone and some degree of osseointegration. The histological findings corresponded well to the mechanical measurements indicating stiffer bone close to the implant, and unaffected skull vibration transmission. Neither CBCT nor CT had enough resolution to visualize the bone to implant interface in detail. In this study, using an animal model, it is shown that a flat implant in contact with bone, can be a feasible method for efficient vibration transmission to the skull bone.
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| 49. |
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| 50. |
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