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Sökning: WFRF:(Sjöberg Johan)

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  • Guevara-Martínez, Mónica, 1989-, et al. (författare)
  • Regulating the production of (R)-3-hydroxybutyrate in Escherichia coli by N or P limitation
  • 2015
  • Ingår i: Frontiers in Microbiology. - : Frontiers Research Foundation. - 1664-302X. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • The chiral compound (R)-3-hydroxybutyrate (3HB) is naturally produced by many wild type organisms as the monomer for polyhydroxybutyrate (PHB). Both compounds are commercially valuable and co-polymeric polyhydroxyalkanoates have been used e.g., in medical applications for skin grafting and as components in pharmaceuticals. In this paper we investigate cultivation strategies for production of 3HB in the previously described E. coil strain AF1000 pJBGT3RX. This strain produces extracellular 3HB by expression of two genes from the PHB pathway of Halomonas boliviensis. H. boliviensis is a newly isolated halophile that forms PHB as a storage compound during carbon excess and simultaneous limitation of another nutrient like nitrogen and phosphorous. We hypothesize that a similar approach can be used to control the flux from acetylCoA to 3HB also in E coli; decreasing the flux to biomass and favoring the pathway to the product. We employed ammonium- or phosphate-limited fed-batch processes for comparison of the productivity at different nutrient limitation or starvation conditions. The feed rate was shown to affect the rate of glucose consumption, respiration, 3HB, and acetic acid production, although the proportions between them were more difficult to affect. The highest 3HB volumetric productivity, 1.5 g L-1 h(-1), was seen for phosphate-limitation.
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  • Lundberg, Olle, et al. (författare)
  • The effect of social protection and income maintenance policies on health and health inequalities
  • 2013
  • Ingår i: European Journal of Public Health. - : Oxford University Press (OUP). - 1101-1262 .- 1464-360X. ; 23:Suppl. 1
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • BackgroundAs a starting point we review the existing evidence on welfare states, health and health inequalities, from 2005 onwards. Three different approaches emerge in these previous studies – the welfare regime approach, the welfare institutions approach and the social spending approach. While no clear picture emerges for the welfare regime approach, summarising findings regarding the institutional and expenditure approach suggest that a higher degree of generosity and social spending benefits public health. These are therefore approaches we follow to arrive at a better understanding of what type of policies are linked to smaller inequalities in health across the life-course.MethodsA starting point in the analyses is the relation between income, poverty and mortality. The cross-national variation in poverty rates, both absolute (poverty threshold) and relative (60 per cent of median income) measure, and mortality rates in European 26 countries will be considered.The second step in the analysis focuses on the relationship between social rights and subjective health in Europe, with a focus on national variations and changes in social rights to levels and changes in subjective health outcomes across several countries. The data holds information regarding social rights and social expenditure, including individual data from EU-SILC.ResultsPreliminary results indicate that it is the totality of social protection that is important rather than individual policies. A sub-study regarding social rights and health among youth highlight also the importance of active and passive labour market policy in the 16 included countries.ConclusionsIn sum our diverse approach to analysing welfare state efforts and their links to health inequalities suggest that there is a clear relationship between more ambitious policies and smaller inequalities in health. These results are discussed in relation to previous findings.
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  • Pöysä, Hannu, et al. (författare)
  • Recovering Whooper Swans do not cause a decline in Eurasian Wigeon via their grazing impact on habitat
  • 2018
  • Ingår i: Journal of Ornithology = Journal fur Ornithologie. - : Springer Science Business Media. - 0021-8375 .- 1439-0361. ; 159, s. 447-455
  • Tidskriftsartikel (refereegranskat)abstract
    • The Whooper Swan (Cygnus cygnus) is a good example of successful conservation, with rapidly growing numbers in Fennoscandia in recent decades. To the contrary, Eurasian Wigeon (Mareca penelope) shows a strong negative trend in breeding numbers, which raises conservation concerns. Previous research suggests a causal link between recent population trajectories of the two species. Both preferentially breed on wetlands with abundant horsetail (Equisetum spp.), a plant providing food for Whooper Swan and crucial feeding microhabitat for Eurasian Wigeon broods. We here test predictions based on the hypothesis that grazing on Equisetum by Whooper Swan reduces breeding habitat or breeding habitat quality for Eurasian Wigeon. We use data from 60 lakes in which waterfowl were counted in 1990–1991 and 2016, and Equisetum was mapped in 1990–1991 and 2013–2014. Lakes colonized by Whooper Swan typically had more abundant Equisetum vegetation in the past than lakes not colonized. Lake-specific decrease of Equisetum was not associated with colonization by Whooper Swan. The number of lakes occupied by Eurasian Wigeon decreased, but the decrease was not stronger on lakes colonized by Whooper Swan than on those that were not. Contrary to our prediction, current Eurasian Wigeon abundance was positively associated with Whooper Swan abundance. Moreover, Eurasian Wigeon did not decrease more on lakes from which Equisetum disappeared than on lakes in which there was still Equisetum left. This study does not support the idea that Whooper Swan affects Eurasian Wigeon negatively by grazing on Equisetum.
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  • Rein-Hedin, Erik, et al. (författare)
  • Utilizing venous occlusion plethysmography to assess vascular effects: A study with buloxibutid, an angiotensin II type 2 receptor agonist
  • 2024
  • Ingår i: Clinical and Translational Science. - : WILEY. - 1752-8054 .- 1752-8062. ; 17:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Buloxibutid (also known as C21) is a potent and selective angiotensin II type 2 receptor (AT2R) agonist, in development for oral treatment of fibrotic lung disease. This phase I, open-label, pharmacodynamic study investigated vascular effects of buloxibutid in five healthy male volunteers. Subjects were administered intra-arterial infusions of buloxibutid for 5 min in ascending doses of 3, 10, 30, 100, and 200 mu g/min, infused sequentially in the forearm. Infusions of sodium nitroprusside (SNP) solution in doses of 0.8-3.2 mu g/min were administered as a positive control. Forearm blood flow (FBF) was measured by venous occlusion plethysmography. Safety and tolerability of intra-arterial administrations of buloxibutid were evaluated. Following infusion of buloxibutid in doses of 3-200 mu g/min, the range of increase in FBF was 27.8%, 17.2%, 37.0%, 28.5%, and 60.5%, compared to the respective baseline. The largest increase was observed in the highest dose group. Infusions of SNP as a positive control, increased FBF 230-320% compared to baseline. Three adverse events (AEs) of mild intensity, not related to buloxibutid or SNP, were reported for two subjects. Two of these AEs were related to study procedures. There were no clinically relevant changes in arterial blood pressure during the study period. Intra-arterial infusion of buloxibutid in low, ascending doses increased FBF, indicating that buloxibutid may be effective in conditions associated with endothelial dysfunction. Venous occlusion plethysmography was found to be a useful method to explore pharmacodynamic vascular effects of novel AT2R agonists, while avoiding systemic adverse effects.
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  • Abbas, Taimoor, et al. (författare)
  • A Measurement Based Shadow Fading Model for Vehicle-to-Vehicle Network Simulations
  • 2015
  • Ingår i: International Journal of Antennas and Propagation. - : Hindawi Publishing Corporation. - 1687-5869 .- 1687-5877.
  • Tidskriftsartikel (refereegranskat)abstract
    • The vehicle-to-vehicle (V2V) propagation channel has significant implications on the design and performance of novel communication protocols for vehicular ad hoc networks (VANETs). Extensive research efforts have been made to develop V2V channel models to be implemented in advanced VANET system simulators for performance evaluation. The impact of shadowing caused by other vehicles has, however, largely been neglected in most of the models, as well as in the system simulations. In this paper we present a shadow fading model targeting system simulations based on real measurements performed in urban and highway scenarios. The measurement data is separated into three categories, line-of-sight (LOS), obstructed line-of-sight (OLOS) by vehicles, and non-line-of-sight due to buildings, with the help of video information recorded during the measurements. It is observed that vehicles obstructing the LOS induce an additional average attenuation of about 10 dB in the received signal power. An approach to incorporate the LOS/OLOS model into existing VANET simulators is also provided. Finally, system level VANET simulation results are presented, showing the difference between the LOS/OLOS model and a channel model based on Nakagami-m fading.
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  • Alhashimi, Anas, 1978- (författare)
  • Statistical Sensor Calibration Algorithms
  • 2018
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The use of sensors is ubiquitous in our IT-based society; smartphones, consumer electronics, wearable devices, healthcare systems, industries, and autonomous cars, to name but a few, rely on quantitative measurements for their operations. Measurements require sensors, but sensor readings are corrupted not only by noise but also, in almost all cases, by deviations resulting from the fact that the characteristics of the sensors typically deviate from their ideal characteristics.This thesis presents a set of methodologies to solve the problem of calibrating sensors with statistical estimation algorithms. The methods generally start with an initial statistical sensor modeling phase in which the main objective is to propose meaningful models that are capable of simultaneously explaining recorded evidence and the physical principle for the operation of the sensor. The proposed calibration methods then typically use training datasets to find point estimates of the parameters of these models and to select their structure (particularlyin terms of the model order) using suitable criteria borrowed from the system identification literature. Subsequently, the proposed methods suggest how to process the newly arriving measurements through opportune filtering algorithms that leverage the previously learned models to improve the accuracy and/or precision of the sensor readings.This thesis thus presents a set of statistical sensor models and their corresponding model learning strategies, and it specifically discusses two cases: the first case is when we have a complete training dataset (where “complete” refers to having some ground-truth informationin the training set); the second case is where the training set should be considered incomplete (i.e., not containing information that should be considered ground truth, which implies requiring other sources of information to be used for the calibration process). In doing so, we consider a set of statistical models consisting of both the case where the variance of the measurement error is fixed (i.e., homoskedastic models) and the case where the variance changes with the measured quantity (i.e., heteroskedastic models). We further analyzethe possibility of learning the models using closed-form expressions (for example, when statistically meaningful, Maximum Likelihood (ML) and Weighted Least Squares (WLS) estimation schemes) and the possibility of using numerical techniques such as Expectation Maximization (EM) or Markov chain Monte Carlo (MCMC) methods (when closed-form solutions are not available or problematic from an implementation perspective). We finally discuss the problem formulation using classical (frequentist) and Bayesian frameworks, and we present several field examples where the proposed calibration techniques are applied on sensors typically used in robotics applications (specifically, triangulation Light Detection and Rangings (Lidars) and Time of Flight (ToF) Lidars).
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  • Alizadeh Khameneh, Mohammad Amin, 1983- (författare)
  • Optimal Design in Geodetic GNSS-based Networks
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • An optimal design of a geodetic network helps the surveying engineers maximise the efficiency of the network. A number of pre-defined quality requirements, i.e. precision, reliability, and cost, of the network are fulfilled by performing an optimisation procedure. Today, this is almost always accomplished by implementing analytical solutions, where the human intervention in the process cycle is limited to defining the requirements. Nevertheless, a trial and error method can be beneficial to some applications. In order to analytically solve an optimisation problem, it can be classified to different orders, where an optimal datum, configuration, and optimal observation weights can be sought such that the precision, reliability and cost criteria are satisfied.In this thesis, which is a compilation of six peer-reviewed papers, we optimised and redesigned a number of GNSS-based monitoring networks in Sweden by developing new methodologies. In addition, optimal design and efficiency of total station establishment with RTK-GNSS is investigated in this research.Sensitivity of a network in detecting displacements is of importance for monitoring purposes. In the first paper, a precision criterion was defined to enable a GNSS-based monitoring network to detect 5 mm displacements at each network point. Developing an optimisation model by considering this precision criterion, reliability and cost yielded a decrease of 17% in the number of observed single baselines implying a reliable and precise network at lower cost. The second paper concerned a case, where the precision of observations could be improved in forthcoming measurements. Thus a new precision criterion was developed to consider this assumption. A significant change was seen in the optimised design of the network for subsequent measurements. As yet, the weight of single baselines was subject to optimisation, while in the third paper, the effect of mathematical correlations between GNSS baselines was considered in the optimisation. Hence, the sessions of observations, including more than two receivers, were optimised. Four out of ten sessions with three simultaneous operating receivers were eliminated in a monitoring network with designed displacement detection of 5 mm. The sixth paper was the last one dealing with optimisation of GNSS networks. The area of interest was divided into a number of three-dimensional elements and the precision of deformation parameters was used in developing a precision criterion. This criterion enabled the network to detect displacements of 3 mm at each point.A total station can be set up in the field by different methods, e.g. free station or setup over a known point. A real-time updated free station method uses RTK-GNSS to determine the coordinates and orientation of a total station. The efficiency of this method in height determination was investigated in the fourth paper. The research produced promising results suggesting using the method as an alternative to traditional levelling under some conditions. Moreover, an optimal location for the total station in free station establishment was studied in the fifth paper. It was numerically shown that the height component has no significant effect on the optimal localisation.
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  • Allard, Erik, 1976-, et al. (författare)
  • Quantitative aspects of analyzing small molecules - monitoring singly or doubly charged ions? : A case study of ximelagatran.
  • 2010
  • Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 24:4, s. 429-435
  • Tidskriftsartikel (refereegranskat)abstract
    • Precision, reproducibility and lower limit of quantitation (LLOQ) are important characteristics of a quantitative method. We have investigated these properties for Ximelagatran (Xi), which has a high tendency to form doubly charged ions in electrospray ionization (ESI), by studying the percentage of doubly charged species formed when varying the formic acid (FA) concentration, analyte concentration, amount of organic modifier and flow rate. It was found that the percentage of [Xi + 2H]2+ can be controlled to be more than 90% or less than 10% by varying the amount of FA present, and that the change between these values is dramatic. Furthermore, the percentage of [Xi + 2H]2+ formed decreases with increased analyte concentration and increased flow rate. No apparent relationship with the amount of organic modifier was found. The results have the implication that, by carefully controlling the selected parameters, the LLOQ, precision and reproducibility can be improved. We have compared the fragmentation of the singly and doubly charged species and concluded that the [Xi + 2H]2+ ion is more inclined to undergo fragmentation than [Xi + H]+. As a consequence, unusual instrumental settings had to be used for the experiments. The fragmentation patterns are to a great extent similar, but the doubly charged species is more inclined to generate low-mass product ions.
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  • Andersson, Johan Vium, 1971- (författare)
  • A Complete Model for Displacement Monitoring Based on Undifferenced GPS Observations
  • 2008
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • During recent years there has been a great focus on the climate changes within the media. More or less every day more newspaper articles are presented about the global warming issue and the effect on us human race. Climate models predict higher temperatures and more rain in the northern part of Europe. It is also predicted that the weather will become more extreme e.g. it will rain a lot during longer periods than has been the norm. If these predictions are correct, the amount of water that is going to be transported away in streams and rivers will increase and so also will the subsoil water level. The latter increases the risk for landslides in areas with fine grained soils. An early warning system that is able to alert people before a landslide take place would be of great interest. The purpose of this work is to develop a complete real-time displacement monitoring system based on observations from several GPS-receivers that could be used as an early warning system. Due to the complex correlation structure of the traditionally used double differences, an alternative method based on undifferenced observations is used. Theoretically this approach shows some advantages and simplifies the correlative structure of observables compared to the double differenced method. A complete model for the undifferenced approach is presented in this thesis including its software implementation. A displacement detection system includes not only the positioning algorithms, but also methods to detect if any displacement occurs. There are many methods available to discriminate displacements, which are used in the traditional control of manufacturing processes. Several of these methods are compared in this thesis, such as the Shewhart chart, different Weighted Moving Average (WMA) charts and the CUmulative SUMmation (CUSUM). Practical tests show that it is possible to detect an abrupt shift on sub centimetre level at the same epoch as the shift occurs. Smaller shifts are also detectable with the applied approach but with a slightly longer detection time.
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  • Andersson, Johan Vium (författare)
  • Undifferenced GPS for Deformation Monitoring
  • 2006
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis contains the development of a deformation monitoring software based on undifferenced GPS observations. Software like this can be used in alarm systems placed in areas where the earth is unstable. Systems like this can be used in areas where people are in risk of getting hurt, like in earthquake zones or in land slide areas, but they can also be useful when monitoring the movements in buildings, bridges and other artefacts. The main hypotheses that are tested are whether it is possible to detect deformations with undifferenced observations and if it is possible to reach the same accuracy in this mode as when working in a traditional mode where the observations are differenced. The development of a deformation monitoring software based on undifferenced GPS observations is presented. A complete mathematical model is given as well as implementation details. The software is developed in Matlab together with a GPS observation simulator. The simulator is mainly used for debugging purposes. The developed software is tested with both simulated and real observations. Results from tests with simulated observations show that it is possible to detect deformations in the order of a few millimetres with the software. Calculations with real observations give the same results. Further, the result from calculations in static mode indicates that the commercial software and the undifferenced software diverge a few millimetres, which probably depends on different implementations of the tropospheric corrections. In kinematic mode the standard deviation is about 1 millimetre larger in the undifferenced mode than in the double differenced mode. An initial test with different observation weighting procedures indicates that there is a lot of potential to improve the result by applying correct weights to the observations. This is one of the aims in the future work within this project. This thesis are sponsored by the Swedish Research Council for Enviroment, Agricultural Sciences and Spatial Planning, FORMAS within the framework “Monitoring of construction and detection of movements by GPS ref no. 2002-1257"
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  • Antepohl, Wolfram, et al. (författare)
  • Interleukin-8 is elevated in cerebrospinal fluid following high-voltage electrical injury with late-onset paraplegia suggesting neuronal damage at the microlevel as causative factor
  • 2010
  • Ingår i: Burns. - : Pergamon Press. - 0305-4179 .- 1879-1409. ; 36:3, s. e7-e9
  • Tidskriftsartikel (refereegranskat)abstract
    • The patient, a 31-year-old male, sustained an electric burn injury (16 kV, AC/DC) while working with electric power lines. He was acutely admitted to a national burn center in Southeast Sweden, where burns equalling 29% of the total body surface area were noted. The burns were located at the front of the abdomen, upper arms bilaterally, and the left hip region, and the lesions were estimated to be mainly of the dermal type, what was believed initially to be caused mainly by an electric flash. There were no obvious entry or exit sites of the electric current. However, myoglobin in plasma was elevated as a sign of muscular degradation, suggesting that at least some current had passed through the tissues. According to the paramedic report there was an episode of a few minutes of unconsciousness immediately after the injury, but the patient was fully awake and alert on admission. There was no concomitant trauma.
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  • Arvidsson, Björn, et al. (författare)
  • Online capillary solid phase extraction and liquid chromatographic separation with quantitative tandem mass spectrometric detection (SPE-LC-MS/MS) of ximelagatran and its metabolites in a complex matrix.
  • 2009
  • Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 877:3, s. 291-297
  • Tidskriftsartikel (refereegranskat)abstract
    • This work presents the development and validation of a fully automated quantitative analysis method of melagatran, its prodrug ximelagatran, and its major metabolites for the study of drug behavior in biofluids. The method involves online sample clean-up and enrichment on a C4 capillary column followed by separation on a capillary C18 column. Electrospray ionization tandem mass spectrometric detection in positive ion mode was performed with multiple reactions monitoring of eight different transients, divided into two time segments with four transients each. The structural similarity, the complexity of the matrix (pig liver extract) and the formation of isobaric fragment ions, made efficient chromatographic separation necessary. The analysis method provides valid accuracy (<9%; RSD%), precision (<8%; RSD%), linearity (<1.2 nM–1 μM; R2 > 0.999), limit of quantitation (<3.6 nM), retention repeatability (<1.2%; RSD%), selectivity, as well as analyte and column stabilities over a wide concentration range.
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  • Arzel, Céline, et al. (författare)
  • Does changing spring phenology affect short and long distance migratory waterfowl similarly?
  • 2010
  • Ingår i: The abstract book. ; , s. 43-
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Among waterfowl, most ducks may be considered income breeders due to their small body size and their limited capacity to store energy. Therefore limited access to resources on their breeding grounds is likely to affect their breeding schedule and potentially output. At northern latitudes, ice break up dictates the access to the breeding lakes. An early ice break up allows for early access to the breeding site and its feeding resources, and potentially leading to higher breeding output than after a late ice break up. Short distance migrants are thus more likely to adapt to ice break up conditions than long distance migrants which have to cope with weather conditions en route and local resource accessibility along the migratory path. Using 20 years of data on breeding phenology and success of 3 species of ducks differing in their migratory strategy - Teal Anas crecca, Mallard Anas platyrhynchos and Common Goldeneye Bucephala clangula - in a watershed in Finland, we test the idea that variation in spring phenology affects the reproductive performance of duck species differently depending on their migration pattern.
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  • Arzel, Céline, et al. (författare)
  • Does changing spring phenology affect short and long distance migratory waterfowl similarly?
  • 2010
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Among waterfowl, most ducks may be considered income breeders due to their small body size and their limited capacity to store energy. Therefore limited access to resources on their breeding grounds is likely to affect their breeding schedule and potentially output. At northern latitudes, ice break up dictates the access to the breeding lakes. An early ice break up allows for early access to the breeding site and its feeding resources, and potentially leading to higher breeding output than after a late ice break up. Short distance migrants are thus more likely to adapt to ice break up conditions than long distance migrants which have to cope with weather conditions en route and local resource accessibility along the migratory path. Using 20 years of data on breeding phenology and success of 3 species of ducks differing in their migratory strategy - Teal Anas crecca, Mallard Anas platyrhynchos and Common Goldeneye Bucephala clangula - in a watershed in Finland, we test the idea that variation in spring phenology affects the reproductive performance of duck species differently depending on their migration pattern.
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  • Arzel, Céline, et al. (författare)
  • Early springs and breeding performance in two sympatric duck species with different migration strategies
  • 2014
  • Ingår i: Ibis. - : Wiley: 12 months. - 0019-1019 .- 1474-919X. ; 156:2, s. 288-298
  • Tidskriftsartikel (refereegranskat)abstract
    • The capacity of migratory species to adapt to climate change may depend on their migratory and reproductive strategies. For example, reproductive output is likely to be influenced by how well migration and nesting are timed to temporal patterns of food abundance, or by temperature variations during the brood rearing phase. Based on two decades (1988–2009) of waterfowl counts from a boreal catchment in southern Finland we assessed how variation in ice break-up date affected nesting phenology and breeding success in two sympatric duck species, Mallard Anas platyrhynchos and Eurasian Teal Anas crecca. In Fennoscandia these species have similar breeding habitat requirements but differ in migration distance; Teal migrate roughly seven times as far as do Mallard. Annual ice break-up date was used as a proxy of spring ‘earliness’ to test the potential effect of climate change on hatching timing and breeding performance. Both species were capable of adapting their nesting phenology, and bred earlier in years when spring was early. However, the interval from ice break-up to hatching tended to be longer in early springs in both species, so that broods hatched relatively later than in late springs. Ice break-up date did not appear to influence annual number of broods per pair or annual mean brood size in either species. Our study therefore does not suggest that breeding performance in Teal and Mallard is negatively affected by advancement of ice break-up at the population level. However, both species showed a within-season decline in brood size with increasing interval between ice break-up and hatching. Our study therefore highlights a disparity between individuals in their capacity to adjust to ice break-up date, late breeders having a lower breeding success than early breeders. We speculate that breeding success of both species may therefore decline should a consistent trend towards earlier springs occur.
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24.
  • Arzel, Céline, et al. (författare)
  • Early springs and breeding performance in two sympatric duck species with different migration strategies
  • 2014
  • Ingår i: Ibis. - : Wiley-Blackwell Publishing Ltd. - 0019-1019 .- 1474-919X. ; 156:2, s. 288-298
  • Tidskriftsartikel (refereegranskat)abstract
    • The capacity of migratory species to adapt to climate change may depend on their migratory and reproductive strategies. For example, reproductive output is likely to be influenced by how well migration and nesting are timed to temporal patterns of food abundance, or by temperature variations during the brood rearing phase. Based on two decades (1988–2009) of waterfowl counts from a boreal catchment in southern Finland we assessed how variation in ice break-up date affected nesting phenology and breeding success in two sympatric duck species, Mallard Anas platyrhynchos and Eurasian Teal Anas crecca. In Fennoscandia these species have similar breeding habitat requirements but differ in migration distance; Teal migrate roughly seven times as far as do Mallard. Annual ice break-up date was used as a proxy of spring ‘earliness’ to test the potential effect of climate change on hatching timing and breeding performance. Both species were capable of adapting their nesting phenology, and bred earlier in years when spring was early. However, the interval from ice break-up to hatching tended to be longer in early springs in both species, so that broods hatched relatively later than in late springs. Ice break-up date did not appear to influence annual number of broods per pair or annual mean brood size in either species. Our study therefore does not suggest that breeding performance in Teal and Mallard is negatively affected by advancement of ice break-up at the population level. However, both species showed a within-season decline in brood size with increasing interval between ice break-up and hatching. Our study therefore highlights a disparity between individuals in their capacity to adjust to ice break-up date, late breeders having a lower breeding success than early breeders. We speculate that breeding success of both species may therefore decline should a consistent trend towards earlier springs occur.
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29.
  • Axehill, Daniel, et al. (författare)
  • Adaptive Cruise Control for Heavy Vehicles
  • 2004
  • Ingår i: Proceedings of Reglermöte 2004.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • An Adaptive Cruise Controller (ACC) is an extension of an ordinary cruise controller. In addition to maintaining a desired set speed, an ACC can also maintain a desired time gap to the vehicle ahead. For this end, both the engine and the brakes are controlled. The interest in the MPC-controller as a solution to the problem was to achieve automatic actuator switching, thus with no explicitly defined switch points. The MPC-controller is based on a model of the system including bounds on the control signals and on linear combinations of the states. Using this knowledge, the MPC-controller will choose the correct actuator for the current driving situation. Among the drawbacks, it can be mentioned that the variant of MPC, used in this paper, is too complex to implement in the control system currently used in trucks.
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30.
  • Axelsson, Christer, et al. (författare)
  • The Early Chain of Care in Patients with Bacteraemia with the Emphasis on the Prehospital Setting
  • 2016
  • Ingår i: Prehospital and Disaster Medicine. - : Cambridge University Press. - 1049-023X .- 1945-1938. ; 31:3, s. 272-277
  • Tidskriftsartikel (refereegranskat)abstract
    • There is a lack of knowledge about the early phase of severe infection. This report describes the early chain of care in bacteraemia as follows: (a) compare patients who were and were not transported by the Emergency Medical Services (EMS); (b) describe various aspects of the EMS chain; and (c) describe factors of importance for the delay to the start of intravenous antibiotics. It was hypothesized that, for patients with suspected sepsis judged by the EMS clinician, the delay until the onset of antibiotic treatment would be shorter.All patients in the Municipality of Gothenburg (Sweden) with a positive blood culture, when assessed at the Laboratory of Bacteriology in the Municipality of Gothenburg, from February 1 through April 30, 2012 took part in the survey.In all, 696 patients fulfilled the inclusion criteria. Their mean age was 76 years and 52% were men. Of all patients, 308 (44%) had been in contact with the EMS and/or the emergency department (ED). Of these 308 patients, 232 (75%) were transported by the EMS and 188 (61%) had “true pathogens” in blood cultures. Patients who were transported by the EMS were older, included more men, and suffered from more severe symptoms and signs.The EMS nurse suspected sepsis in only six percent of the cases. These patients had a delay from arrival at hospital until the start of antibiotics of one hour and 19 minutes versus three hours and 21 minutes among the remaining patients (P =.0006). The corresponding figures for cases with “true pathogens” were one hour and 19 minutes versus three hours and 15 minutes (P =.009).Among patients with bacteraemia, 75% used the EMS, and these patients were older, included more men, and suffered from more severe symptoms and signs. The EMS nurse suspected sepsis in six percent of cases. Regardless of whether or not patients with true pathogens were isolated, a suspicion of sepsis by the EMS clinician at the scene was associated with a shorter delay to the start of antibiotic treatment.
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31.
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32.
  • Bagger, Anette, 1974- (författare)
  • Prövningen av en skola för alla : nationella provet i matematik i det tredje skolåret
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis presents the contribution to research that my doctoral education led to. My starting point was a large scale qualitative research project (here after called the VR-project) which reviewed the implementation of national tests in the third grade on the subject of mathematics. The VR-project investigated how the test affected the pupils with a special focus on pupils in need of special support. An urge to look further into issues concerning the support, the pupil in need and the test was revealed in he initial VR-project. These issues therefore constitutes the problem area of this thesis. The VR-project studied a total of 22 classrooms in two different municipalities' during 2010- 2012. The methodology used for this project was inspired by ethnography and discourse analysis. The raw data consisted of test instructions, video observations of the actual test subjects, interviews from teachers and pupils about the test, the support that was given throughout the testing as well as the observations and interviews of the pupils requiring special assistance. Activated discourses and positions of the participants were demarcated. The results revealed that a traditional testing discourse, a caring discourse and a competitive discourse are activated during the tests. The testing discourse is stable and traditional. Much of what was shown and said in classrooms, routines and rules regarding the test were repeated in all the schools and in all the classrooms. The discourse on support is affected by ambiguity, which is revealed especially when issues of pupils’ equity is put against the tests equality. This is connected to the teachers restricted agency to give support due to the teacher position as a test taker. The positions in need that are available to students are not the same in pupils, teachers and steering documents. The situation is especially troublesome for pupils that do not manage Swedish good enough to take the test and for pupils in need of special support. Some of the conclusions from this thesis is that the national test format: Disciplines not only the pupil, but also the teacher, the classroom and the school at large. Results indicate that the test:Activates a focus on achievementLeads attention away from learning Activates issues of accountability Influences pupils and teachers with stakes involvedBesides evaluating knowledge, the test disciplines not only the pupil, but also the teacher, the classroom and the school at large. Discussing the national test as an arena for equity might be a way towards attaining equality in education for all pupils.
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33.
  • Bergkvist, Max, 1976- (författare)
  • Studies on Polarised Light Spectroscopy
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis project focuses on measurements of dermal microcirculation during vascular provocations with polarised light spectroscopy. This is done with a non-invasive method commercially available as Tissue viability imaging (TiVi) which measures concentration and oxygenation of red blood cells in the papillary dermis. Three studies were done with human subjects and one with an animal model, to validate and compare the TiVi technique with laser Doppler flowmetry, which is an established method of measuring dermal microcirculation.The TiVi consists of a digital camera with polarisation filters in front of the flash and lens, with software for analysis of the picture. When taking a picture with the TiVi, the polarised light that is reflected on the skin surface is absorbed by the second filter over the lens (which is perpendicular to the first filter) but a portion of light penetrates the surface of the skin and is scattered when it is reflected on tissue components. This makes the light depolarised, passes the second filter, and produces a picture for analysis. The red blood cell (RBC) has a distinct absorption pattern that differs between red and green colour compared to melanin and other components of tissue. This difference is used by the software that calculates differences in each picture element and produces a measure of output which is proportional to the concentration of red blood cells. The oxygenation of RBC can also be calculated, as there is a difference in absorption depending on oxygen state.The first paper takes up possible sources of error such as ambient light, and the angle and distance of the camera. The main experiment was to investigate how the local heating reaction is detected with TiVi compared to LDF.In the second paper arterial and venous stasis are examined in healthy subjects with TiVi.The Third paper is an animal study where skin flaps were raised on pigs, and the vascular pedicle is isolated to enable control of inflow and outflow of blood.The measurements were made during partial venous, total venous, and total arterial occlusion. The TiVi recorded changes in the concentration of RBC, oxygenation and heterogeneity and the results were compared with those of laser Doppler flowmetry.In the fourth paper oxygenation and deoxygenation of RBC: s was studied. Studies were made on the forearms of healthy subjects who were exposed to arterial and venous occlusion. Simultaneous measurements were made with TiVi and Enhanced perfusion and oxygen saturation or EPOS, which is a new device that combines laser Doppler flowmetry and diffuse reflectance spectroscopy in one probe.With TiVi, one can measure RBC concentration and oxygenation in the area of an entire picture or in one or multiple user defined regions of interest (ROI). Methods such as laser Doppler flowmetry makes single point measurements, which is a potential source of error both because of the heterogeneity of the microcirculation, and that the circulation be insufficient in the margins of the investigated area. TiVi has been able to measure venous stasis more accurately than laser Doppler flowmetry, and venous stasis is the more common reason for flaps to fail.The TiVi is an accurate way to measure the concentration of RBC and trends in oxygenation of the dermal microcirculation. It has interesting possible applications for microvascular and dermatological research, monitoring of flaps, and diagnosis of peripheral vascular disease. Future clinical studies are needed as well as development of the user interface.  
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34.
  • Bergström, Ulf, et al. (författare)
  • Storskarvens (Phalacrocorax carbo) ekologi, roll i ekosystemet och effekter på fiskbestånd : Sammanställning av kunskap och kunskapsbehov
  • 2023
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Det råder kunskapsbrist om storskarvens ekologi i svenska akvatiska ekosystem och hur fiskpopulationer och ekosystem påverkas av storskarv i olika områden. Framförallt behövs bättre underlag om skarvarnas födoval, födosöksbeteende, antal och migrationer för att kunna bedöma påverkan på fiskpopulationer och ekosystem. Grundläggande underlag om storskarvens biologi, för bättre förståelse av dess ekologiska roll, bör samlas in genom standardiserad och internationellt samordnad övervakning. Akvatiska ekosystem är komplexa och sammanlänkade, med flera arter och ekologiska processer som samverkar med varandra. Fiskpopulationer påverkas även av en rad andra faktorer än predation från storskarv, både biologiska och icke-biologiska. Det kan därför vara svårt att separera effekter från storskarv från annan påverkan. Att dra generella slutsatser om storskarvens påverkan på olika fiskpopulationer i olika områden och under olika tidsperioder är därför svårt. Generellt verkar påverkan från storskarv på fiskpopulationer vara liten i friska ekosystem. Dock verkar skarvpredation kunna ha negativ påverkan på specifika fiskpopulationer, i synnerhet svaga populationer som även påverkas negativt av andra faktorer. För att förbättra kunskapsläget är det viktigt att förvaltningsåtgärder som syftar till att minska storskarvens påverkan på fiskpopulationer följs upp vetenskapligt. Dessa förvaltningsåtgärder bör om möjligt samordnas med andra åtgärder för att öka förståelsen av vilka påverkansfaktorer som har störst betydelse för olika fiskpopulationer.
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35.
  • Berkenstam, Anders, et al. (författare)
  • The thyroid hormone mimetic compound KB2115 lowers plasma LDL cholesterol and stimulates bile acid synthesis without cardiac effects in humans
  • 2008
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 105:2, s. 663-667
  • Tidskriftsartikel (refereegranskat)abstract
    • Atherosclerotic cardiovascular disease is a major problem despite the availability of drugs that influence major risk factors. New treatments are needed, and there is growing interest in therapies that may have multiple actions. Thyroid hormone modulates several cardiovascular risk factors and delays atherosclerosis progression in humans. However, use of thyroid hormone is limited by side effects, especially in the heart. To overcome this limitation, pharmacologically selective thyromimetics that mimic metabolic effects of thyroid hormone and bypass side effects are under development. In animal models, such thyromimetics have been shown to stimulate cholesterol elimination through LDL and HDL pathways and decrease body weight without eliciting side effects. We report here studies on a selective thyromimetic [KB2115, (3-[[3,5-dibromo-4- [4-hydroxy-3-(1-methylethyl)-phenoxy]-phenyl]-amino]-3-oxopropanoic acid)] in humans. In moderately overweight and hypercholesterolemic subjects KB2115 was found to be safe and well tolerated and elicited up to a 40% lowering of total and LDL cholesterol after 14 days of treatment. Bile acid synthesis was stimulated without evidence of increased cholesterol production, indicating that KB2115 induced net cholesterol excretion. KB2115 did not provoke detectable effects on the heart, suggesting that the pharmacological selectivity observed in animal models translates to humans. Thus, selective thyromimetics deserve further study as agents to treat dyslipidemia and other risk factors for atherosclerosis. © 2007 by The National Academy of Sciences of the USA.
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36.
  • Berkius, Johan, et al. (författare)
  • A prospective longitudinal multicentre study of health related quality of life in ICU survivors with COPD
  • 2013
  • Ingår i: Critical Care. - : BioMed Central. - 1364-8535 .- 1466-609X. ; 17:5, s. R211-
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: Mortality amongst COPD patients treated on the ICU is high. Health-related quality of life (HRQL) after intensive care is a relevant concern for COPD patients, their families and providers of health care. Still, there are few HRQL studies after intensive care of this patient group. Our hypothesis was that HRQL of COPD patients treated on the ICU declines rapidly with time.METHODS: Fifty-one COPD patients (COPD-ICU group) with an ICU stay longer than 24 hours received a questionnaire at 6, 12 and 24 months after discharge from ICU. HRQL was measured using two generic instruments: the EuroQoL instrument (EQ-5D and EQ-VAS) and the Short Form 36 Health Survey (SF-36). The results were compared to HRQL of two reference groups from the general population; an age- and sex-adjusted reference population (Non-COPD reference) and a reference group with COPD (COPD reference).RESULTS: HRQL of the COPD-ICU group at 6 months after discharge from ICU was lower compared to the COPD reference group: Median EQ-5D was 0.66 vs. 0.73, P=0.08 and median EQ-VAS was 50 vs.55, P<0.05. There were no significant differences in the SF-36 dimensions between the COPD-ICU and COPD-reference groups, although the difference in physical functioning (PF) approached statistical significance (P=0.059). Patients in the COPD-ICU group who were lost to follow-up after 6 months had low HRQL scores at 6 months. Scores for patients who died were generally lower compared to patients who failed to respond to the questionnaire. The PF and social functioning (SF) scores in those who died were significantly lower compared to patients with a complete follow up. HRQL of patients in the COPD-ICU group that survived a complete 24 months follow up was low but stable with no statistically significant decline from 6 to 24 months after ICU discharge. Their HRQL at 24 months was not significantly different from HRQL in the COPD reference group.CONCLUSIONS: HRQL in COPD survivors after intensive care was low but did not decline from 6 to 24 months after discharge from ICU. Furthermore, HRQL at 24 months was similar to patients with COPD who had not received ICU treatment.
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37.
  • Berkius, Johan, 1960- (författare)
  • Intensive care in chronic obstructive pulmonary disease : treatment with non-invasive ventilation and long-term outcome
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Background: Chronic obstructive pulmonary disease (COPD) is a major cause of chronic morbidity and mortality throughout the world. When we began this project our knowledge about the outcome of COPD patients admitted to the ICU in Sweden was scarce.Aims: To investigate the characteristics, survival and health-related quality of life (HRQL) of COPD patients admitted to Swedish ICUs. To investigate how ICU personnel decide whether to use invasive or non-invasive ventilatory treatment (NIV) of the newly admitted COPD patient in need of ventilatory support. To investigate outcome according to mode of ventilation.Material and methods: Detailed data, including HRQL during recovery, from COPD patients admitted to ICUs that participated in the Swedish intensive care registry were analysed. A questionnaire was distributed to personnel in 6 of the participating ICUs in order to define factors deemed important in making the choice between invasive and non-invasive ventilation immediately after admission. The answers were analysed.Results: The proportion of COPD patients admitted to Swedish ICUs in need of ventilatory support is 1.3-1.6 % of all admissions. The patients are around 70 years-old and are severely ill on admission, with high respiratory rates and most have life-threatening disturbances in their acid-base balance and blood gases. There are more women than men. The short- and long-term mortality is high despite intensive care treatment. The majority of patients are treated with NIV. The length of stay on the ICU is shorter when NIV is used. The choice between NIV and invasive ventilation in these patients may be irrational. It is guided by current guidelines, but other non-patient-related factors seem to influence this decision. NIV seems to be preferable to invasive ventilation at admission, not only according to short-term benefits but also to long-term survival. Failure of NIV followed by invasive ventilation does not have a poorer prognosis than directly employing invasive ventilation. The health-related quality of life of COPD patients after treatment on Swedish ICUs is lower than in the general population. However it does not decline between 6 and 24 months after ICU discharge. After 24 months the HRQL is quite similar to that of COPD patients not treated on the ICU.Conclusions: COPD patients in need of ventilatory support admitted to Swedish ICUs are severely ill on admission, and their short- and long-term mortality is high despite ICU care and ventilatory treatment. Non-invasive ventilation should be the first line treatment on admission. NIV has short- and long-term benefits compared to invasive ventilation, without increasing mortality risk in case of failure. After discharge from the ICU and recovery, the HRQL of COPD patients is lower than in the general population, but comparable to COPD patients not treated on the ICU.
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38.
  • Bhat, Misha, et al. (författare)
  • Longitudinal ECG changes in tetralogy of Fallot and association with surgical repair
  • 2024
  • Ingår i: Frontiers in Cardiovascular Medicine. - 2297-055X. ; 11
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: ECG abnormalities have been linked to adverse changes in right ventricular (RV) morphology and poor clinical outcomes in repaired Tetralogy of Fallot (rTOF). Our aim was to describe how ECG changes progress in early and intermediate follow-up and whether types of surgical strategy at the time of primary repair affected these changes. Methods: We studied patients with rTOF born 2000–2018 operated at our institution. Seven time points in relation to primary repair, follow-up, and pulmonary valve replacement (PVR) were identified. Patients correct with valve sparing repair (VSR), trans-annular patch (TAP) including with a monocusp valve (TAP + M) and with at least 3 ECGs were included. PQ interval, QRS duration, dispersion, and fragmentation, QTc duration and dispersion, JTc as well as presence of a right bundle branch block (RBBB) were analyzed. Medical records were reviewed for demographic and surgical data. Results: Two hundred nineteen patients with 882 ECGs were analyzed with a median follow-up time of 12.3 years (8.4, 17) with 41 (19%) needing PVR during the study period. QRS duration increased at time of primary repair to discharge from 66 msec (IQR 12) to 129 msec (IQR 27) (p < 0.0001) and at 1- and 6- year follow-up but showed only a modest and temporary decrease after PVR. QTc increased at the time of primary repair as well as prior to PVR. PQ interval showed a small increase at the time of primary repair, was at its highest prior to PVR and decreased with PVR. Type of surgical repair affected mainly QTc and JTc and was consistently longer in the TAP + M group until PVR. In VSR, QTc and JTc were prolonged initially compared to TAP but were similar after 1 year. After PVR, there were no differences in adverse ECG changes between surgical groups. Conclusions: PQ interval and QRS duration best correspond to the assumed volume load whereas the relationship with QTc and JTc is more complex, suggesting that these represent more complex remodeling of the myocardium. Before PVR, QTc and JTc are longer in the TAP + M group which may be due to a longer surgical incision.
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39.
  • Bixby, H., et al. (författare)
  • Rising rural body-mass index is the main driver of the global obesity epidemic in adults
  • 2019
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 569:7755, s. 260-4
  • Tidskriftsartikel (refereegranskat)abstract
    • Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities(.)(1,2) This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity(3-6). Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.
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40.
  • Björkholm, Magnus, et al. (författare)
  • Success Story of Targeted Therapy in Chronic Myeloid Leukemia : A Population-Based Study of Patients Diagnosed in Sweden From 1973 to 2008
  • 2011
  • Ingår i: Journal of Clinical Oncology. - 0732-183X .- 1527-7755. ; 29:18, s. 2514-2520
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose Chronic myeloid leukemia (CML) management changed dramatically with the development of imatinib mesylate (IM), the first tyrosine kinase inhibitor targeting the BCR-ABL1 oncoprotein. In Sweden, the drug was approved in November 2001. We report relative survival (RS) of patients with CML diagnosed during a 36-year period. Patients and Methods Using data from the population-based Swedish Cancer Registry and population life tables, we estimated RS for all patients diagnosed with CML from 1973 to 2008 (n = 3,173; 1,796 males and 1,377 females; median age, 62 years). Patients were categorized into five age groups and five calendar periods, the last being 2001 to 2008. Information on use of upfront IM was collected from the Swedish CML registry. Results Relative survival improved with each calendar period, with the greatest improvement between 1994-2000 and 2001-2008. Five-year cumulative relative survival ratios (95% CIs) were 0.21 (0.17 to 0.24) for patients diagnosed 1973-1979, 0.54 (0.50 to 0.58) for 1994-2000, and 0.80 (0.75 to 0.83) for 2001-2008. This improvement was confined to patients younger than 79 years of age. Five-year RSRs for patients diagnosed from 2001 to 2008 were 0.91 (95% CI, 0.85 to 0.94) and 0.25 (95% CI, 0.10 to 0.47) for patients younger than 50 and older than 79 years, respectively. Men had inferior outcome. Upfront overall use of IM increased from 40% (2002) to 84% (2006). Only 18% of patients older than 80 years of age received IM as first-line therapy. Conclusion This large population-based study shows a major improvement in outcome of patients with CML up to 79 years of age diagnosed from 2001 to 2008, mainly caused by an increasing use of IM. The elderly still have poorer outcome, partly because of a limited use of IM.
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41.
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42.
  • Bryhn, Andreas, et al. (författare)
  • Fisk- och skaldjursbestånd i hav och sötvatten 2019 : Resursöversikt
  • 2020
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Fisken i havet är en resurs som rör sig fritt över nationella gränser. EU har därför en gemensam fiskeripolitik (GFP). Många arter som är viktiga för Sverige regleras inte i GFP och förvaltas därför nationellt.Denna rapport syftar till att:beskriva utvecklingen av fiskeripolitikenförklara den nuvarande politikens mål och regelverk och dess relation till mål och regler på miljöområdetförklara politikens nationella genomförande och det nationella handlingsutrymmetexemplifiera hur Havs- och vattenmyndigheten arbetat med att reglera fisket.
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43.
  • Bryhn, Andreas, et al. (författare)
  • Fisk- och skaldjursbestånd i hav och sötvatten 2020 : Resursöversikt
  • 2021
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • I rapporten kan du ta del av bedömningen som görs av situationen för bestånd som regleras inom ramen för EU:s gemensamma fiskeripolitik (GFP). Bedömningarna baseras på det forskningssamarbete och den rådgivning som sker inom det Internationella Havsforskningsrådet (ICES). Totalt redovisas underlag och råd för 48 fisk- och skaldjursarter.De bestånd som förvaltas nationellt baseras på de biologiska underlagen, och rådgivningen i huvudsak på den forskning och övervakning samt analys som bedrivs av Institutionen för akvatiska resurser vid Sveriges lantbruksuniversitet (SLU Aqua) samt yrkesfiskets rapportering.
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44.
  • Butler, Simon, et al. (författare)
  • An Investigation of Work Practices Used by Companies Making Contributions to Established OSS Projects
  • 2018
  • Ingår i: ICSE-SEIP '18 Proceedings of the 40th International Conference on Software Engineering: Software Engineering in Practice. - New York : Association for Computing Machinery (ACM). - 9781450356596 ; , s. 201-210
  • Konferensbidrag (refereegranskat)abstract
    • Professionals contribute to open source software (OSS) projects aspart of their employment. Previous research has addressed motivationsof individuals and the ways they engage with OSS projects.However, there is a lack of research which examines and explainswork practices used by companies in their engagement with projects.Work practices used by companies to contribute to five establishedOSS projects are investigated through examination of the actions ofemployees in public communication channels and draw on our experienceswhen analysing engagement with the same projects. Wefind that companies utilise work practices for contributing whichare congruent with the circumstances and their capabilities thatsupport their short and long term needs. We find that companiescontribute to OSS projects in different ways, such as employing coreproject developers, making donations, and joining project steeringcommittees in order to advance strategic interests.
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45.
  • Butler, Simon, et al. (författare)
  • On Company Contributions to Community Open Source Software Projects
  • 2021
  • Ingår i: IEEE Transactions on Software Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0098-5589 .- 1939-3520. ; 47:7, s. 1381-1401
  • Tidskriftsartikel (refereegranskat)abstract
    • The majority of contributions to community open source software (OSS) projects are made by practitioners acting on behalf of companies and other organisations. Previous research has addressed the motivations of both individuals and companies to engage with OSS projects. However, limited research has been undertaken that examines and explains the practical mechanisms or work practices used by companies and their developers to pursue their commercial and technical objectives when engaging with OSS projects. This research investigates the variety of work practices used in public communication channels by company contributors to engage with and contribute to eight community OSS projects. Through interviews with contributors to the eight projects we draw on their experiences and insights to explore the motivations to use particular methods of contribution. We find that companies utilise work practices for contributing to community projects which are congruent with the circumstances and their capabilities that support their short- and long-term needs. We also find that companies contribute to community OSS projects in ways that may not always be apparent from public sources, such as employing core project developers, making donations, and joining project steering committees in order to advance strategic interests. The factors influencing contributor work practices can be complex and are often dynamic arising from considerations such as company and project structure, as well as technical concerns and commercial strategies. The business context in which software created by the OSS project is deployed is also found to influence contributor work practices.
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46.
  • Bäckman, Johan, et al. (författare)
  • Activity and migratory flights of individual free-flying songbirds throughout the annual cycle : Method and first case study
  • 2017
  • Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 48:2, s. 309-319
  • Tidskriftsartikel (refereegranskat)abstract
    • We describe a method and device (< 1.2 g) for recording, processing and storing data about activity and location of individuals of free-living songbirds throughout the annual cycle. Activity level was determined every five minutes from five 100 ms samples of accelerometer data with 5 s between the sampling events. Activity levels were stored on an hourly basis throughout the annual cycle, allowing periods of resting/sleep, continuous flight and intermediate activity (foraging, breeding) to be distinguished. Measurements from a light sensor were stored from preprogrammed key stationary periods during the year to provide control information about geographic location. Successful results, including annual actogram, were obtained for a red-backed shrike Lanius collurio carrying out its annual loop migration between northern Europe and southern Africa. The shrike completed its annual migration by performing > 66 (max. 73) nocturnal migratory flights (29 flights in autumn and > 37, max. 44, in spring) adding up to a total of > 434 (max. 495) flight hours. Migratory flights lasted on average 6.6 h with maximum 15.9 h. These flights were aggregated into eight travel episodes (periods of 4-11 nights when flights took place on the majority of nights). Daytime resting levels were much higher during the winter period compared to breeding and final part of spring migration. Daytime resting showed peaks during days between successive nocturnal flights across Sahara, continental Africa and the Arabian Peninsula, indicating that the bird was mostly sleeping between these long migratory flights. Annual activity and flight data for free-living songbirds will open up many new research possibilities. Main topics that can be addressed are e.g. migratory flight performance (total flight investment, numbers and characteristics of flights), timing of stationary periods, activity patterns (resting/sleep, activity level) in different phases of the annual cycle and variability in the annual activity patterns between and within individuals.
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47.
  • Bäckman, Johan, et al. (författare)
  • Actogram analysis of free-flying migratory birds : new perspectives based on acceleration logging
  • 2017
  • Ingår i: Journal of Comparative Physiology A. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 203:6-7, s. 543-564
  • Tidskriftsartikel (refereegranskat)abstract
    • The use of accelerometers has become an important part of biologging techniques for large-sized birds with accelerometer data providing information about flight mode, wing-beat pattern, behaviour and energy expenditure. Such data show that birds using much energy-saving soaring/gliding flight like frigatebirds and swifts can stay airborne without landing for several months. Successful accelerometer studies have recently been conducted also for free-flying small songbirds during their entire annual cycle. Here we review the principles and possibilities for accelerometer studies in bird migration. We use the first annual actograms (for red-backed shrike Lanius collurio) to explore new analyses and insights that become possible with accelerometer data. Actogram data allow precise estimates of numbers of flights, flight durations as well as departure/landing times during the annual cycle. Annual and diurnal rhythms of migratory flights, as well as prolonged nocturnal flights across desert barriers are illustrated. The shifting balance between flight, rest and different intensities of activity throughout the year as revealed by actogram data can be used to analyse exertion levels during different phases of the life cycle. Accelerometer recording of the annual activity patterns of individual birds will open up a new dimension in bird migration research.
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48.
  • Carlson, Johan, et al. (författare)
  • A noise-tolerant group delay estimator applied to dispersion measurement in gases
  • 2003
  • Ingår i: Proceedings, 2003 IEEE Ultrasonics Symposium. - Piscataway, NJ : IEEE Communications Society. - 0780379225 ; , s. 254-257
  • Konferensbidrag (refereegranskat)abstract
    • In this paper we present a model-based group velocity estimator, that can be used to measure speed of sound in ultrasonic pulse-echo systems as a function of ultrasound frequency. The estimation of group velocities involves numerical differentiation of the phase difference. In the presence of noise, this becomes numerically unstable. The model-based approach presented herein, shows better tolerance to experimental noise. The performance of the estimator is evaluated with simulations as function of pulse bandwidth and SNR. Finally, the estimator applied to real data and compared with other methods for measuring speed of sound in Ethane and Oxygen.
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49.
  • Carlson, Johan, et al. (författare)
  • Echo-cancellation in a single-transducer ultrasonic imaging system
  • 2002
  • Ingår i: NORSIG 2002. - Trondheim : The Institute of Electrical and Electronics Engineers. - 8299315840
  • Konferensbidrag (refereegranskat)abstract
    • During the last ten years, time-reversal of acoustic fields have been shown to be a very useful technique in ultrasonic imaging and testing. With the use of transducer arrays, it is possible to steer the sound beam to an arbitrary position within the medium, even if the medium is inhomogeneous or contains scatterers. The major drawback with traditional beamforming and time-reversal techniques is that they require the use of transducer arrays. Recently a new technique was presented that, with the use of a waveguide, makes it possible to focus sound arbitrarily, with only one transducer elements. A problem with the setup is that the signal-to-noise ratio (SNR) is degraded because of interfering echoes from the waveguide. In this paper, we present an echo-cancellation scheme that results in an SNR gain of approximately 33 dB. This enables the new technique to be used in pulse-echo mode, where this was not previously possible.
  •  
50.
  • Carlson, Johan, et al. (författare)
  • Simultaneous maximum likelihood estimation of time delay and time scaling
  • 2004
  • Ingår i: Norsig 2004. - Helsinki : Helsinki University of Technology. - 9789512270651 ; , s. 260-263
  • Konferensbidrag (refereegranskat)abstract
    • In this paper we present a simultaneous maximum likelihood estimator (ML) for time delay and time-scaling in the presence of additive white Gaussian Noise. The Cram´er- Rao lower bound for the variance of the estimates is also derived. The performance of the estimator is evaluated for ultrasound echoes for different time-scalings and different time delays. The performance is compared to the standard cross-correlation estimator.
  •  
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