| 1. |
- Sävblom, C, et al.
(författare)
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Association between polymorphisms in the prostate-specific antigen (PSA) promoter and release of PSA
- 2009
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Ingår i: International Journal of Andrology. - : Wiley-Blackwell. - 0105-6263 .- 1365-2605. ; 32:5, s. 479-485
-
Tidskriftsartikel (refereegranskat)abstract
- Variations in serum prostate-specific antigen (PSA) have been ascribed to A/G nucleotide polymorphisms located at -158 bp (rs266882) and -4643 bp (rs925013), relative to the transcription start site within the promoter of the PSA gene. PSA is also an androgen receptor target (AR) gene and polymorphisms in AR gene are known to affect AR function. Our objective was to compare the impact of these A/G polymorphisms separately or in combination with AR CAG micro satellite on regulation of PSA secretion into seminal plasma and blood in young men. Leukocyte DNA was extracted from 291 conscripts and genotyping performed with the Sequenom Mass Array System. PSA was measured with an immunofluorometric assay. Linear regression analysis was used to test the association of polymorphism frequencies with serum and seminal plasma levels of PSA. PSA gene polymorphisms at -158 bp or -4643 bp did not alone influence total PSA (tPSA) levels in seminal plasma or in blood. Homozygotes for the A-allele at -158 bp in combination with CAG > 22 had significantly higher serum levels of tPSA than subjects carrying the G-allele (p = 0.01). In conclusion, the PSA gene polymorphisms did not importantly influence the levels of tPSA in seminal plasma or in blood. tPSA in serum was influenced by interactions between PSA promoter variants and AR CAG polymorphism.
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| 2. |
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| 3. |
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| 4. |
- Andersson, Christer, et al.
(författare)
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Enabling anonymity for the mobile Internet using the mCrowds system
- 2004
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Ingår i: Risk and Challenges of the Network Society. - : Karlstad University Press. ; , s. 178-189
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Bokkapitel (refereegranskat)abstract
- The mobile Internet is a fast growing technology that introduces new privacy risks. We argue that, since privacy legislation alone is not sufficient to protect the users privacy, technical solutions to enhanceinformational privacy of individuals are also needed. This paper introduces mCrowds, a privacy-enhancing technology that combines the concept of a crowd system in a mobile Internet setting with a filteringfunctionality to enable anonymity towards the content providers
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| 5. |
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| 6. |
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| 7. |
- Andersson, Christer, et al.
(författare)
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On the Fundamentals of Anonymity Metrics
- 2008
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Ingår i: The Future of Identity in the Information Society. - Boston, MA : Springer-Verlag New York. - 9780387790268 ; , s. 325-341
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Bokkapitel (refereegranskat)
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| 8. |
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| 9. |
- Andersson, Evert, et al.
(författare)
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Bygg de nya stambanorna! (Debatt)
- 2023
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Ingår i: Jönköpings-Posten. - 1103-9469. ; , s. 3-3
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Arne, Mats, 1954-, et al.
(författare)
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Factors associated with good self-rated health and quality of life in subjects with self-reported COPD
- 2011
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Ingår i: The International Journal of Chronic Obstructive Pulmonary Disease. - 1176-9106 .- 1178-2005. ; 6, s. 511-519
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recent guidelines for chronic obstructive pulmonary disease (COPD) state that COPD is both preventable and treatable. To gain a more positive outlook on the disease it is interesting to investigate factors associated with good, self-rated health and quality of life in subjects with self-reported COPD in the population. Methods: In a cross-sectional study design, postal survey questionnaires were sent to a stratified, random population in Sweden in 2004 and 2008. The prevalence of subjects (40–84 years) who reported having COPD was 2.1% in 2004 and 2.7% in 2008. Data were analyzed for 1475 subjects. Regression models were used to analyze the associations between health measures (general health status, the General Health Questionnaire, the EuroQol five-dimension questionnaire) and influencing factors. Results: The most important factor associated with good, self-rated health and quality of life was level of physical activity. Odds ratios for general health varied from 2.4 to 7.7 depending on degree of physical activity, where subjects with the highest physical activity level reported the best health and also highest quality of life. Social support and absence of economic problems almost doubled the odds ratios for better health and quality of life. Conclusions: In this population-based public health survey, better self-rated health status and quality of life in subjects with self-reported COPD was associated with higher levels of physical activity, social support, and absence of economic problems. The findings indicated that of possible factors that could be influenced, promoting physical activity and strengthening social support are important in maintaining or improving the health and quality of life in subjects with COPD. Severity of the disease as a possible confounding effect should be investigated in future population studies.
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| 15. |
- Barup, Kerstin, et al.
(författare)
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Multi-disciplinary lidar applications
- 2010
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Ingår i: Laser Applications to Chemical, Security and Environmental Analysis, LACSEA 2010. - 2162-2701. - 9781557528803
-
Konferensbidrag (refereegranskat)abstract
- Lidar is a powerful technique normally associated with atmospheric monitoring. However, lidar techniques, also of the laser-induced fluorescence and laser-induced breakdown spectroscopy varieties, provide many new possibilities in unconventional fields including cultural heritage and ecological applications.
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| 16. |
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| 17. |
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| 18. |
- Eklöf, Jenny, 1973-
(författare)
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Gene technology at stake : Swedish governmental commissions on the border of science and politics
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines the Swedish political response to the challenges posed by gene technology, seen through the prism of governmental commissions. It discerns and analyses continuities and changes in the Swedish political conception of gene technology, over the course of two decades, 1980–2000. This is done by thematically following ideas of “risks” and “ethics” as they are represented in the inner workings and reception of three governmental commissions. The Gene-Ethics Commission (1981–1984), the Gene Technology Commission (1990–1992) and the Biotechnology Commission (1997–2000) form the empirical focal points of this analysis. The first two provided preparatory policy proposals that preceded the implementation of the Swedish gene technology laws of 1991 and 1994. The last one aimed at presenting a comprehensive Swedish biotechnology policy for the new millennium.The study takes into account the role of governmental commissions as arenas where science and politics intersect in Swedish political life, and illuminates how this type of “boundary organisation”, placed on the border of science and politics, impinges on the understanding of the gene technology issue. The commissions have looked into the limits, dangers, possibilities and future applications of gene technology. They have been appointed to deal with the problematic task of distinguishing between what is routine and untested practices, realistic prediction and “science fiction”, what are unique problems and what are problems substantially similar to older ones, what constitutes a responsible approach as opposed to misconduct and what it means to let things “get out of hand” in contrast to being “in control”. Throughout a period of twenty years, media reports have continued to frame the challenges posed by gene technology as a task of balancing risks and benefits, walking the fine line between “frankenfoods” and “miracle drugs”.One salient problem for the commissions to solve was that science and industry seemed to promote a technology the public opposed and resisted, at least in parts. For both politics and science to gain, or regain, public trust it needed to demonstrate that risks – be it environmental, ethical or health related ones – were under control. Under the surface, it was much more complicated than “science helping politics” to make informed and rational decisions on how to formulate a regulatory policy. Could experts be trusted to participate in policy-making in a neutral way and was it not important, in accordance with democratic norms, to involve the public?
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| 19. |
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| 20. |
- Eldh, Christer, et al.
(författare)
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En otidsenlig kropp
- 1996
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Ingår i: Kroppens tid. - 9127062015 ; , s. 179-196
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Bokkapitel (populärvet., debatt m.m.)
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| 21. |
- Ellmark, Peter, et al.
(författare)
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Identification of protein expression signatures associated with Helicobacter pylori infection and gastric adenocarcinoma using recombinant antibody microarrays.
- 2006
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Ingår i: Molecular & cellular proteomics : MCP. - 1535-9476 .- 1535-9484. ; 5:9, s. 1638-46
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Tidskriftsartikel (refereegranskat)abstract
- Antibody microarray based technology is a powerful emerging tool in proteomics, target discovery, and differential analysis. Here, we report the first study where recombinant antibody fragments have been used to construct large scale antibody microarrays, composed of 127 different antibodies against mostly immunoregulatory antigens. The arrays were based on single framework recombinant antibody fragments (SinFabs) designed for high on-chip stability and functionality and were used for the analysis of malignant and normal stomach tissue samples from Helicobacter pylori-positive and -negative patients. Our results demonstrate that distinct tumor- as well as infection-associated protein expression signatures could be identified from these complex tissue proteomes, as well as biomarkers such as IL-9, IL-11, and MCP-4, previously not found in these diseases. In a longer perspective, this study may improve the understanding of H. pylori-induced stomach cancer and lead to development of improved diagnostics.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Fagrell, Tobias G, et al.
(författare)
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Aetiology of severe demarcated enamel opacities--an evaluation based on prospective medical and social data from 17,000 children.
- 2011
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Ingår i: Swedish dental journal. - : Swedish Dental Journal (Sveriges Tandlakarforbund). - 0347-9994. ; 35:2, s. 57-67
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Tidskriftsartikel (refereegranskat)abstract
- During the 1970s dentists reported an increasing prevalence of a "new" type of enamel disturbance.The disturbance was very specific, with areas of demarcated hypomineralised enamel, and was mostly found in permanent first molars and incisors. Several studies have tried to reveal the aetiology behind the enamel disturbance but sofar no clear factors correlated have been found. The aim of the present study was to evaluate aetiological factors to severe demarcated opacities (SDO) in first permanent molars in a large cohort of children enrolled in the "All Babies in Southeast Sweden" (ABIS) project. ABIS is a prospective study of all children in five Swedish counties born between Oct 1, 1997 and Oct 1, 1999, in all about 17,000 children.They have been followed from birth with recording of a large number of factors on nutrition, diseases, medication, infections, social situation etc. With help from 89 Public Dental Service clinics in the same area preliminary examinations of the children, born between Oct 1,1997 and Oct 1,1999, reported 595 children with severe demarcated opacities (SDO) in first molars.These children and a randomly selected age matched group of 1,200 children were further invited to be examined by specialists in paediatric dentistry. At these examinations 224 severe cases were identified as well as 253 children completely without enamel disturbances among children registered in ABIS.These two groups were analysed according to any correlation between SDO and variables in the ABIS databank. The analyses showed no association between SDO and pre-, peri-, and neonatal data. However, we found a positive association between SDO and breastfeeding for more than 6 months (OR 1.9; 95% CI 1.1-3.2), late introduction of gruel (OR 1.9; 95% CI 1.1-2.9), and late introduction of infant formula (OR 1.8; 95% CI 1.2-2.9). A combination of these three variables increased the risk to develop SDO by more than five times (OR 5.1; 95% CI 1.6-15.7). No significant associations were found to other environmental, developmental, or medical factors. We conclude that nutritional conditions during first 6 months of life may influence the risk to develop severe demarcated opacities in first permanent molars.
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| 26. |
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| 27. |
- Guerrero, José-Luis, 1977-, et al.
(författare)
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Exploring the hydrological robustness of model-parameter values with alpha shapes
- 2013
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 49:10, s. 6700-6715
-
Tidskriftsartikel (refereegranskat)abstract
- Estimation of parameter values in hydrological models has gradually moved from subjective, trial-and-error methods into objective estimation methods. Translation of nature's complexity to bit operations is an uncertain process as a result of data errors, epistemic gaps, computational deficiencies, and other limitations, and relies on calibration to fit model output to observed data. The robustness of the calibrated parameter values to these types of uncertainties is therefore an important concern. In this study, we investigated how the hydrological robustness of the model-parameter values varied within the geometric structure of the behavioral (well-performing) parameter space with a depth function based on α shapes and an in-depth posterior performance analysis of the simulations in relation to the observed discharge uncertainty. The α shape depth is a nonconvex measure that may provide an accurate and tight delimitation of the geometric structure of the behavioral space for both unimodal and multimodal parameter-value distributions. WASMOD, a parsimonious rainfall-runoff model, was applied to six Honduran and one UK catchment, with differing data quality and hydrological characteristics. Model evaluation was done with two performance measures, the Nash-Sutcliffe efficiency and one based on flow-duration curves. Deep parameter vectors were in general found to be more hydrologically robust than shallow ones in the analyses we performed; model-performance values increased with depth, deviations to the observed data for the high-flow aspects of the hydrograph generally decreased with increasing depth, deep parameter vectors generally transferred in time with maintained high performance values, and the model had a low sensitivity to small changes in the parameter values. The tight delimitation of the behavioral space provided by the α shapes depth function showed a potential to improve the efficiency of calibration techniques that require further exploration. For computational reasons only a three-parameter model could be used, which limited the applicability of this depth measure and the conclusions drawn in this paper, especially concerning hydrological robustness at low flows.
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| 28. |
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| 29. |
- Guerrero, Jose-Luis, et al.
(författare)
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Temporal variability in stage-discharge relationships
- 2012
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 446, s. 90-102
-
Tidskriftsartikel (refereegranskat)abstract
- Although discharge estimations are central for water management and hydropower, there are few studies on the variability and uncertainty of their basis; deriving discharge from stage heights through the use of a rating curve that depends on riverbed geometry. A large fraction of the world's river-discharge stations are presumably located in alluvial channels where riverbed characteristics may change over time because of erosion and sedimentation. This study was conducted to analyse and quantify the dynamic relationship between stage and discharge and to determine to what degree currently used methods are able to account for such variability. The study was carried out for six hydrometric stations in the upper Choluteca River basin, Honduras, where a set of unusually frequent stage-discharge data are available. The temporal variability and the uncertainty of the rating curve and its parameters were analysed through a Monte Carlo (MC) analysis on a moving window of data using the Generalised Likelihood Uncertainty Estimation (GLUE) methodology. Acceptable ranges for the values of the rating-curve parameters were determined from riverbed surveys at the six stations, and the sampling space was constrained according to those ranges, using three-dimensional alpha shapes. Temporal variability was analysed in three ways: (i) with annually updated rating curves (simulating Honduran practices), (ii) a rating curve for each time window, and (iii) a smoothed, continuous dynamic rating curve derived from the MC analysis. The temporal variability of the rating parameters translated into a high rating-curve variability. The variability could turn out as increasing or decreasing trends and/or cyclic behaviour. There was a tendency at all stations to a seasonal variability. The discharge at a given stage could vary by a factor of two or more. The quotient in discharge volumes estimated from dynamic and static rating curves varied between 0.5 and 1.5. The difference between discharge volumes derived from static and dynamic curves was largest for sub-daily ratings but stayed large also for monthly and yearly totals. The relative uncertainty was largest for low flows but it was considerable also for intermediate and large flows. The standard procedure of adjusting rating curves when calculated and observed discharge differ by more than 5% would have required continuously updated rating curves at the studied locations. We believe that these findings can be applicable to many other discharge stations around the globe.
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| 30. |
- Halldin, Sven, et al.
(författare)
-
Energy, water and carbon exchange in a boreal forest landscape - NOPEX experiences
- 1999
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Ingår i: Agricultural and Forest Meteorology. - 0168-1923 .- 1873-2240. ; 98-9:SI, s. 5-29
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Forskningsöversikt (refereegranskat)abstract
- The role of the land surface in controlling climate is still underestimated and access to information from the boreal-forest zone is instrumental to improve this situation. This motivated the organisation of NOPEX (Northern hemisphere climate-Processes land-surface Experiment) in the southern part of the European boreal zone. This paper summarises results from NOPEX in its first phase, dealing with spring- and summertime conditions. Two concentrated field efforts (CFE1 on 27 May-23 June 1994, CFE2 on 18 April-14 July 1995) were carried out with coordinated measurements of energy, water, and CO2 budgets at 13 ground-based sites and at various airborne platforms. Flux aggregation was a central issue in the heterogeneous, patchy NOPEX landscape. It is shown that simple land-use-weighted averaging of fluxes from fields/forests/lakes agree well with regional fluxes. Momentum fluxes can be parameterised over the whole area with a roughness length of approximately 1.5 m, whereas fluxes of sensible heat and other scalars depend on the averaging scale, Local measurements of soil moisture can be classified and meaningful averages can be deduced with a 1 km resolution. Lakes play an important role and differs in both diurnal and annual cycles compared to the forests and fields. Multiannual data from an agricultural and a forest site has allowed quantification and modelling of seldom occuring phenomena. One unexpected result was that the Norunda Common forest acted as a source and not a sink of CO2. The successful completion of CFE1-2 and a pilot winter campaign (CFE3) will lead NOPEX into its final phase, devoted to wintertime processes. Measurements and model results reside in SINOP. the System for Information in NOPEX, open for NOPEX participants. Data from CFE1 and CFE2 are released on CD as an integrated part of this Special Issue. (C) 1999 Elsevier Science B.V. All rights reserved.
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| 31. |
- Halldin, Sven, et al.
(författare)
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NOPEX - a northern hemisphere climate processes land surface experiment
- 1998
-
Ingår i: Journal of Hydrology. - 0022-1694 .- 1879-2707. ; 212-213, s. 172-187
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Tidskriftsartikel (refereegranskat)abstract
- The interface between land surfaces and the atmosphere is a key area in climate research, where lack of basic knowledge prevents us from reducing the considerable uncertainties about predicted changes. Boreal forests play an important, but not well known, role in the global hydrological and biogeochemical cycles. NOPEX (a NOrthern hemisphere climate Processes land surface EXperiment) is devoted to the study of land surface-atmosphere interaction in a northern European forest-dominated landscape. The main NOPEX region represents the southern edge of the boreal zone. It consists of a highly heterogeneous landscape, with forests, mires, agricultural land and lakes. A second study site, in northern Finland, representing the northern edge of the boreal zone, will be introduced into NOPEX in connection with its coming winter-time field activities. Field activities, dominating the initial phase of NOPEX, are conceived to strike a balance between the need to cover multi-annual observations and the resources required to carry out measurements covering all relevant spatial scales. The long-term data collection activities, the Continuous Climate Monitoring (CCM), form the backbone of the field programme. A suite of Concentrated Field Efforts (CFEs) covering periods of summer, spring and winter brings together scientists from more then 20 countries during month-long campaigns. CFEs have been carried out in May-June 1994 and April-July 1995. A third, winter-time CFE is planned for 1998-99. The System for Information in NOPEX (SINOP) is the database which forms a backbone for modelling and analysis work, dominating the second stage of NOPEX. A series of PhD courses are run in parallell to the research activities. Analysis and modelling are done in four interacting areas, including local-scale processes, meso-scale surface-atmosphere coupling and remote sensing techniques. The fourth area, regionalization methods, aims at bringing the previous three together in order to provide improved parameterization schemes for exchange of energy, momentum, water and CO2 between land and atmosphere in hydrological and meteorological models from the meso to the global scale.
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| 32. |
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| 33. |
- Hansson, Klas, et al.
(författare)
-
Equifinality and sensitivity in freezing and thawing simulations of laboratory and in situ data
- 2006
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Ingår i: Cold Regions Science and Technology. - : Elsevier BV. - 0165-232X .- 1872-7441. ; 44:1, s. 20-37
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Tidskriftsartikel (refereegranskat)abstract
- Numerical models of soil freezing and thawing are being increasingly used in, e.g., agriculture, forestry, ecology and civil engineering. This study was conducted to 1) elucidate the sensitivity in simulation output to the variability of model parameters for the hydrodynamic model Hydrus-1D and 2) investigate how two operational considerations in the model setup, groundwater level and subgrade material (soil texture), affect indicators of road accessibility in northern Sweden. The analysis was carried out by applying the generalized likelihood uncertainty estimation (GLUE) procedure when simulating laboratory measurements of freezing cylinders and by a more conventional sensitivity analysis, varying one parameter at a time, using road surface temperatures measured during nearly 1 year as upper boundary condition. For the simulation of the laboratory experiment, it was found that, although the thermal conductivity scaling factor, λf, and the convective heat transfer coefficient, hc, most strongly affected the output, no parameter was redundant for the given problem. The frost depth was most sensitive to changes in λf and hc, while the water content in the unfrozen zone was most sensitive to changes in the hydraulic conductivity impedence parameter Ω. For the 1-year road simulation, the frost depth was larger for sand than for the loam and silt subgrades; the thawing period was shortest for sand and longest for the silt subgrade; and the silt subgrade allowed for the largest frost-induced upward water flow. Thus, among the subgrades studied, roads built on silt show the potential of being most frost-susceptible as a consequence of having the largest elevated water content in combination with the longest time of thawing. The study performed indicates that the model can provide information of interest from an operational perspective, allowing for local predictions important in the road construction and maintenance process.
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| 34. |
- Hansson, Klas, et al.
(författare)
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Modeling water flow patterns in flexible pavement
- 2005
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Ingår i: TRB 2005 Annual Meeting.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Most road design models do not explicitly account for moisture transport mechanisms in roads even though it is well known that water content plays an important role in the deterioration of roads. The Swedish National Road Administration aims to improve the current situation by supporting the development of models that eventually can provide a better and more complete description of the road/environment system. The water transport model used in this manuscript is one such model. The objective of this study was to investigate the applicability of hydrological theories and methods to the road/environment system. Particular attention was paid to flow patterns inside the road as affected by capillary barriers, and generated by mechanisms of surface runoff followed by infiltration into cracks and the embankment. The effect of rain intensity, precipitated amount, and/or fracture conductivity on the flow patterns was investigated using numerical particle tracking. Changes in rain intensity had a small effect on flow patterns but velocities were higher for larger rain intensities. Both changes in precipitated amount and fracture conductivity controlled the appearance of the flow patterns while capillary barrier effects were limited. The numerical code used proved to be appropriate in describing the relevant processes.
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| 35. |
- Hansson, Klas, et al.
(författare)
-
Modeling water flow patterns in flexible pavements
- 2005
-
Ingår i: Transportation Research Record. - Washington D.C. : Transportation Research Board of the National Academies. - 0361-1981 .- 2169-4052. ; 1936, s. 133-141, s. 133-141
-
Tidskriftsartikel (refereegranskat)abstract
- Most road design models do not explicitly account for moisture transport mechanisms in roads, even though it is well known that water content plays an important part in the deterioration of roads. The Swedish National Road Administration aims to improve the current situation by supporting the development of models that eventually can provide a better and more complete description of the road and environment system. The applicability of hydrological theories and methods to the road and environment system was investigated. Particular attention was paid to flow patterns inside the road as affected by capillary barriers and generated by mechanisms of surface runoff, followed by infiltration into cracks, and the embankment. Particle tracking was used to investigate the effect of rain intensity, precipitated amount, or fracture conductivity on the flow patterns. Changes in rain intensity had a small effect on flow patterns, but velocities were higher for larger rain intensities. Both changes in precipitated amount and fracture conductivity controlled the appearance of the flow patterns, but capillary barrier effects were limited. The numerical code used proved to be mostly appropriate in describing the relevant processes.
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| 36. |
- Hansson, Klas, 1972-
(författare)
-
Water and Heat Transport in Road Structures : Development of Mechanistic Models
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The coupled transport of water and heat, involving freezing and thawing, in the road structure and its immediate environment is important to consider for optimal design and maintenance of roads and when assessing solute transport, of e.g. de-icing salt, from roads. The objective of this study was to develop mechanistic models, and measurement techniques, suitable to describe and understand water flow and heat flux in road structures exposed to a cold climate. Freezing and thawing was accounted for by implementing new routines in two numerical models (HYDRUS1D/2D). The sensitivity of the model output to changes in parameter values and operational hydrological data was investigated by uncertainty and sensitivity analyses. The effect of rainfall event characteristics and asphalt fractures on the subsurface flow pattern was investigated by scenario modelling. The performance of water content reflectometers (WCR), measuring water content, was evaluated using measurements in two road structure materials. A numerical model was used to simulate WCR sensor response. The freezing/thawing routines were stable and provided results in agreement with laboratory measurements. Frost depth, thawing period, and freezing-induced water redistribution in a model road was greatly affected by groundwater level and type of subgrade. The simulated subsurface flow patterns corresponded well with published field observations. A new method was successful in enabling the application of time domain reflectometer (TDR) calibration equations to WCR output. The observed distortion in sampling volume for one of the road materials could be explained by the WCR sensor numerical model. Soil physical, hydrological, and hydraulic modules proved successful in simulating the coupled transport of water and heat in and on the road structure. It was demonstrated in this thesis that numerical models can improve the interpretation and explanation of measurements. The HYDRUS model was an accurate and pedagogical tool, clearly useful in road design and management.
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| 37. |
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| 38. |
- Hansson, Klas, et al.
(författare)
-
Water flow and heat transport in frozen soil : Numerical solution and freeze-thaw applications
- 2004
-
Ingår i: Vadose Zone Journal. - : Wiley. - 1539-1663. ; 3:2, s. 693-704
-
Tidskriftsartikel (refereegranskat)abstract
- A new method is presented to account for phase changes in a fully implicit numerical model for coupled heat transport and variably saturated water flow involving conditions both above and below zero temperature. The method is based on a mixed formulation for both water flow and heat transport similar to the approach commonly used for the Richards equation. The approach enabled numerically stable, energy- and mass-conservative solutions. The model was evaluated by comparing predictions with data from laboratory column freezing experiments. These experiments involved 20-cm long soil columns with an internal diameter of 8 cm that were exposed at the top to a circulating fluid with a temperature of −6°C. Water and soil in the columns froze from the top down during the experiment, with the freezing process inducing significant water redistribution within the soil. A new function is proposed to better describe the dependency of the thermal conductivity on the ice and water contents of frozen soils. Predicted values of the total water content compared well with measured values. The model proved to be numerically stable also for a hypothetical road problem involving simultaneous heat transport and water flow. The problem was simulated using measured values of the surface temperature for the duration of almost 1 yr. Since the road was snow-plowed during winter, surface temperatures varied more rapidly, and reached much lower values, than would have been the case under a natural snow cover. The numerical experiments demonstrate the ability of the code to cope with rapidly changing boundary conditions and very nonlinear water content and pressure head distributions in the soil profile.
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| 39. |
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| 40. |
- Håkanson, Lars, et al.
(författare)
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5. The Baltic Sea
- 2003. - 1
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Ingår i: Environmental Science. - Uppsala : Baltic University Press. - 9197001708 ; , s. 120-147, s. 120-146
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Bokkapitel (populärvet., debatt m.m.)
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| 41. |
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IMPROVER D2.2 Report of criteria for evaluating resilience
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the recent years, the focus has moved from critical infrastructure protection to that of resilience. But how do we know whether a critical infrastructure is resilient or not, how can it be evaluated, measured and enhanced? Drawing on, combining and developing the ideas of the existing literature and practices, the current report develops a holistic, easy-to-use and computable methodology to evaluate critical infrastructure resilience, called Critical Infrastructure Resilience Index (CIRI). The methodology is applicable to all types of critical infrastructure, including a possibility to tailor it to the specific needs of different sectors, facilities and hazard scenarios. The proposed methodology is especially suitable for organizational and technological resilience evaluation, but permits including also elements of societal resilience indicators to the evaluations. The methodology is based on four levels of hierarchically organized indicators. Level 1 consists of the phases well known from the so-called crisis management cycle. Under these phases, we find sets of Level 2 rather generic indicators. Thus under level 1 ‘Prevention’, for instance, we may find a Level 2 indicator such as ‘Resilient design’, further divided into Level 3 more detailed indicators such as ‘Physical robustness’, ‘Cyber robustness’, ‘Redundancy’, ‘Modularity’, and ‘Independency’. The task is to study these indicators on Level 4 in the context of concrete critical infrastructure facilities and hazard scenarios, that is, applying Level 3 indicators into concrete circumstances. The methodology then permits to transfer quantitative, semi-quantitative and qualitative evaluations of individual sector-specific resilience indicators into uniform metrics, based on process maturity levels. This in turn makes it possible to give a specific critical infrastructure, or its part, a resilience value on the scale 0-5. While the real resilience value becomes clear only when one engages in the analysis of several indicators, the methodology can be used also as a step-by-step measurement and development tool for resilience, without necessary immediately engaging in time-consuming total resilience analysis. The user of this methodology is supposed to be the operator of critical infrastructure, or part of it, in the spirit of self-auditing. In case it would be implemented in a wider scale, in cooperation between the operators and authorities, it would give the authorities a holistic picture about the respective society’s critical infrastructure resilience. In this report, we draw a concise picture of the methodology and illustrate how this methodology could be applied to a specific infrastructure and hazard scenario.
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| 42. |
- Johnsson, Holger, et al.
(författare)
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Experimental system for one-dimensional freezing of undisturbed soil profiles
- 1995
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Ingår i: Soil Technology. - 0933-3630. ; 7:4, s. 319-325
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Tidskriftsartikel (refereegranskat)abstract
- An inexpensive and easy-to-handle setup for freeze-thaw experiments was developed. The system mimics field conditions, with a relatively deep monolith of undisturbed soil and a soil-air interface as an upper boundary condition. The setup includes a freezing device for vertical freezing of a soil monolith and transducers at several depths in the soil monolith for continuous measurement of unfrozen water content (TDR), temperature and radial temperature differences, The setup makes rudimentary control of boundary conditions and sophisticated monitoring of soil water and heat conditions possible. To study the performance of the system, soil temperatures and water contents in a clay soil monolith were measured during two freeze-thaw cycles, The setup was shown to be useful in terms of simulating freeze-thaw cycles in a lysimeter placed in the laboratory. One-dimensional heat flows could be simulated, with a thermal error (horizontal vs vertical heat flows) during freezing of about 5%. The setup was used to test the hypothesis that the similitude between freezing/thawing and drying/wetting holds for unsaturated day soils, The results indicated a good agreement between water retention curves calculated from freezing-point depression data and from measurements, using pressure plates.
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| 43. |
- Johnsson, Holger, et al.
(författare)
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Surface runoff and soil water percolation as affected by snow and soil frost
- 1991
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Ingår i: Journal of Hydrology. - 0022-1694 .- 1879-2707. ; 122:1-4, s. 141-159
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Tidskriftsartikel (refereegranskat)abstract
- A coupled soil water and heat model was used to study the influence of soil frost and snow on infiltration and drainage flow in an agricultural field in central Sweden. An analogy between freezing/thawing and drying/wetting was assumed for the soil frost submodel. Model simulations were evaluated against measurements of total soil water content, unfrozen water content, soil temperature and drainage water-flow. The influences of soil frost and spatial variation in snow cover were studied by simulation of possible extreme situations in the field. The model accurately described the dynamics of soil temperature and water contents; however, infiltration and field drainage flow were considerably underestimated and delayed by about three weeks under frozen conditions. A model simulation, discounting the effects of soil frost, overestimated the drain response. An attempt at simulating the field variation in snow cover by assuming possible 'sink points' for snowmelt, explained part of the deviations between simulated and measured drain flows. A basis for a new model formulation of the infiltration and percolation processes in frozen soil is proposed in which two water-flow domains are assumed, one low-flow domain in the fine pores, smaller than those filled with ice, and one high-flow domain in the large air-filled pores. This allows the simulation of rapid infiltration in large ice-free pores and drainage flow under frozen conditions as well as the resulting redistribution of ice from smaller to larger pores.
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| 44. |
- Jonsson, Sarah, 1982-
(författare)
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Pelvic inflammatory disease and epithelial ovarian tumors
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Epithelial ovarian cancer and borderline ovarian tumors consist of several histotypes in which high-grade serous carcinoma is the most common. The majority of epithelial ovarian tumors are considered to originate in the fimbriated end of the fallopian tubes. What initiates these tumors is far from completely understood. Pelvic inflammatory disease has been proposed as a modifiable risk factor for epithelial ovarian tumors. A major cause of pelvic inflammatory disease is Chlamydia trachomatis which has been shown to have cancer-causing potential. The overall purpose of this thesis was to study associations of pelvic inflammatory disease and C. trachomatis with risk of epithelial ovarian tumors.Methods: In a cross-sectional study (Paper I) we collected ovarian tissue and corresponding blood samples from 69 women undergoing surgery due to suspected ovarian pathology. C. trachomatis specific protein (immunohistochemistry) and C. trachomatis DNA (qPCR) in ovarian tissue were analyzed (Paper I). In a nested case-control study (Paper II) prospective blood samples from 92 women diagnosed with high-grade serous ovarian cancer were matched to four controls each for age and date of plasma sampling. C. trachomatis specific plasma antibodies were analyzed by commercial Enzyme-Linked ImmunoSorbent Assay (ELISA) and Micro-ImmunoFluorescence (MIF) (Paper I and Paper II). We performed a nationwide register-based case-control study where we included 15 072 women diagnosed with epithelial ovarian cancer (Paper III), 4782 women diagnosed with borderline ovarian tumors (Paper IV), and ten controls each matched for age and residential district. Using national Swedish registers, we retrieved data on historyof pelvic inflammatory disease and the potential confounding factors parity, educational level, previous gynecological surgery, and hormonal therapy.Results: We found C. trachomatis DNA in ovarian tissue of eight women with ovarian carcinoma, but not in ovarian tissue from women with borderline ovarian tumors or benign disease (Paper I). The prevalence of the C. trachomatis specific protein did not differ in benign and malignant tissue (Paper I). Prevalence of C. trachomatis specific plasma antibodies was similar in cases and controls at diagnosis (Paper I) and prospectively (Paper II). A history of clinically verified pelvic inflammatory disease was associated with an increased risk of epithelial ovarian cancer overall (Paper III) and borderline ovarian tumors overall (Paper IV). Histotype-specific analyses showed an increased risk of serous carcinoma (Paper III), high-grade serous carcinoma (Paper III), clear cell carcinoma (Paper III), and serous borderline ovarian tumors (Paper IV) but not significantly with other histotypes. A dose-response relationship was seen between an increased number of pelvic inflammatory disease episodes and epithelial ovarian cancer (Paper III), as well as borderline ovarian tumors (Paper IV).Conclusions: This thesis contributes to an improved understanding of the association between pelvic inflammatory disease and epithelial ovarian tumors. The results regarding C. trachomatis are inconclusive and suggests that the association of pelvic inflammatory disease with epithelial ovarian tumors acts through mechanisms other than Chlamydia alone.
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| 45. |
- Kellner, Erik, et al.
(författare)
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Calibration of time domain reflectometry for water content in peat soil
- 2001
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Ingår i: Nordic Hydrology. - 0029-1277 .- 1996-9694. ; 32:4-5, s. 315-332
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Tidskriftsartikel (refereegranskat)abstract
- Since peat soil differs from mineral soil in several respects, mineral-soil calibration functions for time domain reflectometry (TDR) are not necessarily applicable. This paper evaluates a number of calibration functions, both empirical polynomial and theoretical mixing models, on the basis of laboratory measurements on undisturbed Sphagnum peat samples. Deviations between different samples within this study indicate dissimilarities in dielectric properties between peats with different degrees of humification. Connections to physical properties such as amount of bound water and structural orientation are likely to exist. There is, however, a lack of methods to measure and quantify parameters expressing these properties. Therefore, until further studies on physical properties are accomplished, empirical or semi-empirical calibration curves are preferred. The best fit was obtained by an empirical, third order polynomial model. This model also gave a better fit than the mixing models when data were grouped into humification classes. However, all models reproduced pooled data with an r(2) better than 0.93.
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| 46. |
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| 47. |
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| 48. |
- Lundin, Lars-Christer, et al.
(författare)
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Continuous long-term measurements of soil-plant-atmosphere variables at a forest site
- 1999
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Ingår i: Agricultural and Forest Meteorology. - 0168-1923 .- 1873-2240. ; 98-99, s. 53-73
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Tidskriftsartikel (refereegranskat)abstract
- It is a major challenge in modem science to decrease the uncertainty in predictions of global climate change. One of the largest uncertainties in present-day global climate models resides with the understanding of processes in the soil-vegetation-atmosphere-transfer (SVAT) system. Continuous, long-term data are needed in order to correctly quantify balances of water, energy and CO2 in this system and to correctly model it. It is the objective of this paper to demonstrate how a combined system of existing sensor, computer, and network technologies could be set up to provide continuous and reliable long-term SVAT-process data from a forested site under almost all environmental conditions. The Central Tower Site (CTS) system was set up in 1993-1994 in a 25 m high boreal forest growing on a highly heterogeneous till soil with a high content of stones and blocks. It has successfully monitored relevant states and fluxes in the system, such as atmospheric fluxes of momentum, heat, water vapour and CO2, atmospheric profiles of temperature, water vapour, CO2, short-and long-wave radiation, heat storage in soil and trees, sap-dow and a variety of ecophysiological properties, soil-water contents and tensions, and groundwater levels, rainfall and throughfall. System uptime has been more than 90% for most of its components during the first 5 years of operation. Results from the first 5 years of operation include e.g., budgets for energy, water and CO2, information on important but rarely occurring events such as evaporation from snow-covered canopies, and reactions of the forest to extreme drought. The carbon budget shows that the forest may be a sink of carbon although it is still growing. The completeness of the data has made it possible to test the internal consistency of SVAT models. The pioneering set-up at the CTS has been adopted by a large number of SVAT-monitoring sites around the world. Questions concerning tower maintenance, long-term calibration plans, maintenance of sensors and data-collection system, and continuous development of the computer network to keep it up to date are, however, only partly of interest as a research project in itself. It is thus difficult to get it funded from usual research-funding agencies. The full value of data generated by the CTS system can best be appreciated after a decade or more of continuous operation. Main uses of the data would be to evaluate how SVAT models handle the natural variability of climate conditions, quantification of water. carbon and energy budgets during various weather conditions, rind development of new parameterisation schemes in global and regional climate models.
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| 49. |
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| 50. |
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