| 1. |
|
|
| 2. |
- Carling, Karin, et al.
(författare)
-
Vacancies in metals : From first-principles calculations to experimental data
- 2000
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 85:18, s. 3862-3865
-
Tidskriftsartikel (refereegranskat)abstract
- We have revealed, and resolved, an apparent inability of density functional theory, within the local density and generalized gradient approximations, to describe vacancies in Al accurately and consistently. The shortcoming is due to electron correlation effects near electronic edges and we show how to correct for them. We find that the divacancy in Al is energetically unstable and we show that anharmonic atomic vibrations explain the non-Arrhenius temperature dependence of the vacancy concentration.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Ahadi, Aylin, et al.
(författare)
-
Simulation of a Friction Stir Welding Process using FE technique
- 2006
-
Ingår i: Report TVSM. - 0281-6679.
-
Konferensbidrag (refereegranskat)abstract
- In this paper a three dimensional FE model of the friction stir welding (FSW) is presented and the FSW process is simulated. The model has been implemented in FE code Abaqus with user subroutines DLOAD, DFLUX and UMASFL. The material data used to describe the welded panels is from an aluminium alloy called AL-2024-T3 and the material is assumed to be isotropic with temperature dependent yield stress and elastic modulus. A nonlinear-coupled thermo-mechanical analysis was performed in order to study the temperature and stress distribution.
|
|
| 7. |
- Ahlström, Christer, et al.
(författare)
-
Fit-for-duty test for estimation of drivers sleepiness level: Eye movements improve the sleep/wake predictor
- 2013
-
Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 26, s. 20-32
-
Tidskriftsartikel (refereegranskat)abstract
- Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a drivers sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS andgt;= 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.
|
|
| 8. |
- Amanullah, Rahman, et al.
(författare)
-
Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 μm
- 2015
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 453:3, s. 3300-3328
-
Tidskriftsartikel (refereegranskat)abstract
- We present ultraviolet (UV) observations of six nearby Type Ia supernovae (SNe Ia) obtained with the Hubble Space Telescope, three of which were also observed in the near-IR (NIR) with Wide-Field Camera 3. UV observations with the Swift satellite, as well as ground-based optical and NIR data provide complementary information. The combined data set covers the wavelength range 0.2-2 mu m. By also including archival data of SN 2014J, we analyse a sample spanning observed colour excesses up to E(B - V) = 1.4 mag. We study the wavelength-dependent extinction of each individual SN and find a diversity of reddening laws when characterized by the total-to-selective extinction R-V. In particular, we note that for the two SNe with E(B - V) greater than or similar to 1 mag, for which the colour excess is dominated by dust extinction, we find R-V = 1.4 +/- 0.1 and R-V = 2.8 +/- 0.1. Adding UV photometry reduces the uncertainty of fitted R-V by similar to 50 per cent allowing us to also measure R-V of individual low-extinction objects which point to a similar diversity, currently not accounted for in the analyses when SNe Ia are used for studying the expansion history of the Universe.
|
|
| 9. |
- Andersson, Anders, et al.
(författare)
-
A transcriptional timetable of autumn senescence
- 2004
-
Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 5:4, s. R24-
-
Tidskriftsartikel (refereegranskat)abstract
- Background We have developed genomic tools to allow the genus Populus (aspens and cottonwoods) to be exploited as a full-featured model for investigating fundamental aspects of tree biology. We have undertaken large-scale expressed sequence tag (EST) sequencing programs and created Populus microarrays with significant gene coverage. One of the important aspects of plant biology that cannot be studied in annual plants is the gene activity involved in the induction of autumn leaf senescence. Results On the basis of 36,354 Populus ESTs, obtained from seven cDNA libraries, we have created a DNA microarray consisting of 13,490 clones, spotted in duplicate. Of these clones, 12,376 (92%) were confirmed by resequencing and all sequences were annotated and functionally classified. Here we have used the microarray to study transcript abundance in leaves of a free-growing aspen tree (Populus tremula) in northern Sweden during natural autumn senescence. Of the 13,490 spotted clones, 3,792 represented genes with significant expression in all leaf samples from the seven studied dates. Conclusions We observed a major shift in gene expression, coinciding with massive chlorophyll degradation, that reflected a shift from photosynthetic competence to energy generation by mitochondrial respiration, oxidation of fatty acids and nutrient mobilization. Autumn senescence had much in common with senescence in annual plants; for example many proteases were induced. We also found evidence for increased transcriptional activity before the appearance of visible signs of senescence, presumably preparing the leaf for degradation of its components.
|
|
| 10. |
- Andersson Ersman, Peter, et al.
(författare)
-
Screen printed digital circuits based on vertical organicelectrochemical transistors
- 2017
-
Ingår i: Flexible and Printed Electronics. - : IOP Publishing. - 2058-8585. ; 2
-
Tidskriftsartikel (refereegranskat)abstract
- Vertical organic electrochemical transistors (OECTs) have been manufactured solely using screenprinting. The OECTs are based on PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)), which defines the active material for both the transistor channel and the gateelectrode. The resulting vertical OECT devices and circuits exhibit low-voltage operation, relativelyfast switching, small footprint and high manufacturing yield; the last three parameters are explainedby the reliance of the transistor configuration on a robust structure in which the electrolyte verticallybridges the bottom channel and the top gate electrode. Two different architectures of the verticalOECT have been manufactured, characterized and evaluated in parallel throughout this report. Inaddition to the experimental work, SPICE models enabling simulations of standalone OECTs andOECT-based circuits have been developed. Our findings may pave the way for fully integrated, lowvoltageoperating and printed signal processing systems integrated with e.g. printed batteries, solarcells, sensors and communication interfaces. Such technology can then serve a low-cost basetechnology for the internet of things, smart packaging and home diagnostics applications.
|
|
| 11. |
|
|
| 12. |
- Andersson, Roland, et al.
(författare)
-
Implantation Metastases from Gastrointestinal Cancer after Percutaneous Puncture or Biliary Drainage
- 1996
-
Ingår i: European Journal of Surgery. - 1102-4151. ; 162:7, s. 551-554
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Evaluation of incidence and outcome of implantation metastases after percutaneous fine-needle biopsy or biliary drainage. Design: Retrospective study. Setting: University hospital, Sweden. Subjects: Eight patients with implantation metastases from gastrointestinal cancers after percutaneous fine-needle biopsy (n = 7) or biliary drainage (n = 1). Main outcome measures: Incidence of implantation metastases, treatment and influence on outcome and survival. Results: In two out of three patients who had had otherwise radical operations, the implantation metastases meant that the operations were palliative rather than curative. Patients who had had palliative resections of the implantation metastases developed major local complications. One patient is alive with no signs of disease after 106 months, while one is alive with disease 30 months after the diagnosis of the implantation metastases. The remaining patients have died after 6 to 23 months. Conclusion: The incidence of implantation metastases after fine-needle procedures is probably underestimated. There is a slight but definite risk that the procedure may render an otherwise curative resection palliative. Implantation metastases cause local complaints of varying severity and seems to have a tendency to recur locally. We recommend that fine-needle biopsy should be restricted to patients who will truly benefit from a more accurate preoperative diagnosis.
|
|
| 13. |
- Andreas, Sandberg, et al.
(författare)
-
Limits on Lyman Continuum Escape from z = 2.2 Hα-emitting Galaxies
- 2015
-
Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 814:1
-
Tidskriftsartikel (refereegranskat)abstract
- The leakage of Lyman continuum (LyC) photons from star-forming galaxies is an elusive parameter. When observed, it provides a wealth of information on star formation in galaxies and on the geometry of the interstellar medium, and puts constraints on the role of star-forming galaxies in the reionization of the universe. Hα-selected galaxies at trace the highest star formation population at the peak of cosmic star formation history, providing a base for directly measuring LyC escape. Here we present this method and highlight its benefits as well as caveats. We also use the method on 10 Hα emitters in the Chandra Deep Field South at also imaged with the Hubble Space Telescope in the ultraviolet. We find no individual LyC detections, and our stack puts a 5σ upper limit on the average absolute escape fraction of <24%, consistent with similar studies. With future planned observations, the sample sizes should rapidly increase and the method presented here should provide very robust constraints on the escape fraction.
|
|
| 14. |
- Aspeborg, Henrik, 1970-, et al.
(författare)
-
Vegetabile material, plants and a method of producing a plant having altered lignin properties
- 2008
-
Patent (populärvet., debatt m.m.)abstract
- The present invention is related to a set of genes, which when modified in plants gives altered lignin properties. The invention provides DNA construct such as a vector useful in the method of the invention. Further, the invention relates to a plant cell or plant progeny of the plants and wood produced by the plants according to the invention Lower lignin levels will result in improved saccharification for bio-refining and ethanol production and improved pulp and paper. Increased lignin levels will utilise lignin properties for energy production. The genes and DNA constructs may be used for the identification of plants having altered lignin characteristics as compared to the wild-type. According to the invention genes and DNA constructs may also be used as candidate genes in marker assisted breeding.
|
|
| 15. |
- Augustsson, Fredrik, 1974-
(författare)
-
They Did IT : The Formation and Organisation of Interactive Media Production in Sweden
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of the study is to describe and explain the formation and organisation of interactive media production in Sweden from the 1990s to the end of 2003, the period of the so-called IT boom and crash, through the development of a theoretical model and gathering of empirical material.In the theory, interactive media production is conceptualised as a practice in part taking place on a social field structured according to the division and integration of labour within and between firms, and logics and status. It is argued that social fields are formed through the entrepreneurial realisation of opportunity structures resting in pre-existing structural configurations, and through the allocation of resources. The organisational outcome is explained by the structural preconditions, aspects of formation (what, who, how) and firms’ demands for stability and flexibility, creating a set of interrelated positions that firms might occupy.Empirical data has been collected from four firm and one individual level survey aimed at interactive media producers in Sweden, conducted between 1997 and 2003. A second data source consists of 8,000 news articles and items focussed on IT and interactive media in Sweden. Third, visual analyses of web sites of firms producing interactive media solutions have been conducted. Finally, interviews with people active within the field have been made.The results show that the formation of interactive media production in Sweden should be understood in relation to the Swedish economic crisis of the early 1990s, visions of IT, and beliefs in a societal transition to a new economy and knowledge society. These ideas contributed to allocating massive resources, e.g. state initiatives, increased demands and investment capital, to those producers of interactive media solutions that came to be symbols of the new economy. The abundance of resources caused a rapid growth of firms engaged in interactive media production and a financialisation that led to a speculative bubble and a stock market crash, eventually making the social field dissolve.The majority of firms that produce interactive media solutions are small and reach flexibility and stability by having a large proportion of permanently employed skilled workers and extensively participating in collaborations with other firms, including customers. The division and integration of labour follows the logics and clusters of activities that structure the social field: techno¬logy, aesthetics and economy. A large proportion of Swedish organisations have further developed inhouse interactive media operations that taken together are larger than the more visible so-called Internet consultants.
|
|
| 16. |
|
|
| 17. |
- Bard, Delphine, et al.
(författare)
-
Human footsteps induced floor vibration.
- 2008
-
Ingår i: The Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 1520-8524 .- 0001-4966. ; 123:5, s. 3356-3356
-
Tidskriftsartikel (refereegranskat)abstract
- The generation of the impact sound by the act of the human walk involves two factors, the characters of the footfall and the shape of the induced floor deflection. The footfall noise is created by the impact excitation and the characters of the footfall depend on the foot-ware: the heels and the frequencies of the footfall. The shape of the floor deflection depends rather on the geometrical walking pattern and the construction of the floor structure. In this investigation, the vibration patter of the light-weight construction floor is created by the same walking object, a male with common height. The excitation from the person to the floor in the FE simulations is a function of the length of the foot and the weight of the walking object. The geometrical time history is of the foot step allows it to have different directions in the room. Since the excitation is assumed to be deterministic, differences between the excitation frequencies are estimated from the video records. The goal of this investigation is to determine the difference of the floor structure deflections between two different walking paths: one is perpendicular to the bearing beams and the other is the diagonal path.
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Beldie, Liliana, et al.
(författare)
-
Paperboard packages exposed to static loads–finite element modelling and experiments
- 2001
-
Ingår i: Packaging Technology & Science. - : Wiley. - 0894-3214. ; 14:4, s. 171-178
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to analyse the mechanical behaviour of paperboard packages subjected to static compressive loads. The study was divided in three parts and experiments and finite element analysis conducted for each part. First, a panel of paperboard was subjected to edge compressive loading as a means of checking the material model. Second, the package was cut into segments and each segment was subjected to compression in order to determine the contribution of the different parts to the overall behaviour of the package. Third, a whole package loaded in compression was studied. In the finite element simulations, the paperboard was modelled as an orthotropic, linear, elastic–plastic laminate. The study utilized a non-linear finite element analysis, based on the plasticity of the material and large displacements. The results show that the middle segment of the package exhibits a higher stiffness than that of the upper and lower package segments and that of the whole package, which leads to the conclusion that the low initial stiffness of the package is a consequence of the low stiffness of the upper and lower corners, i.e. of the horizontal creases. Copyright © 2001 John Wiley & Sons, Ltd.
|
|
| 22. |
- Berggren, Göran, et al.
(författare)
-
Pilotmontage av nytt fasadelementsystem i trä - Fasaden i staden Snabb Snygg Smart
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is about the evaluation of the pilot installation of a new wooden façade element system that was mounted on two four-story timber buildings. Technical solutions were evaluated, mounting time, moisture and deformations were measured, and interviews were conducted with builders on-site. The mounting started in April 2020 and was followed-up with measurements and interviews during 2020. The two buildings were built by Lindbäcks Bygg AB on Porsön in Luleå, Sweden and the developer was Lindbäcks Fastigheter AB. The façade elements were prefabricated by Lindbäcks Bygg AB in the factory at Öjebyn in Piteå Sweden. The mounting work went well, and the builders were positive about the facade system. When the builders had learned how to carry out the work, it took three minutes per façade element, which is equivalent to 0.9 m2/min. This is faster than the traditional installation of a facade on a construction site. The assembly around the windows took about 10 minutes, which is about the same time as in traditional assembly. During 8 months of measurements the average moisture content (MC) behind the façade elements was about 20% during winter (low T, high RH) and about 11% during summer. That is within expected values due to the annual variation in climate. The deformation was measured with laser scanning and gave a deviation of ±1 cm from a perfect plane, indicating a better dimensional stability than traditionally mounted wooden facades. From a working environment perspective, the assembly work was quieter as no nail guns were needed and the builders did not need to handle individual panel boards. Significantly less nails and screws were needed compared to traditional assembly. Experience from the assembly show the possibility for improvements. The construction platform was not optimal for loading elements during assembly. When the builders had gained some experience of the system, the limitation was to get the elements up quickly enough. A fast and efficient assembly requires a detailed planning in the design phase, and the elements should be numbered in a logical way and sufficient packaging needs to be secured. The promising results show the potential for a future way to manufacture and mount wooden facades. “The facade of the city Swift Stylish Smart” is a project within the strategic program Bioinnovation founded by Vinnova (Sweden’s innovation agency), Energimyndigheten (Swedish Energy Agency), Formas (A Swedish Research Council for Sustainable Development), and the industry partners.
|
|
| 23. |
- Berthomier, M., et al.
(författare)
-
Alfven : magnetosphere-ionosphere connection explorers
- 2012
-
Ingår i: Experimental astronomy. - Dordrecht : Springer. - 0922-6435 .- 1572-9508. ; 33:2-3, s. 445-489
-
Tidskriftsartikel (refereegranskat)abstract
- The aurorae are dynamic, luminous displays that grace the night skies of Earth's high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between the solar wind-driven magnetosphere and the ionospheric environment at the top of Earth's atmosphere play a central role. In this Auroral Acceleration Region (AAR) persistent electric fields directed along the magnetic field accelerate magnetospheric electrons to the high energies needed to excite luminosity when they hit the atmosphere. The "ideal magnetohydrodynamics" description of space plasmas which is useful in much of the magnetosphere cannot be used to understand the AAR. The AAR has been studied by a small number of single spacecraft missions which revealed an environment rich in wave-particle interactions, plasma turbulence, and nonlinear acceleration processes, acting on a variety of spatio-temporal scales. The pioneering 4-spacecraft Cluster magnetospheric research mission is now fortuitously visiting the AAR, but its particle instruments are too slow to allow resolve many of the key plasma physics phenomena. The Alfv,n concept is designed specifically to take the next step in studying the aurora, by making the crucial high-time resolution, multi-scale measurements in the AAR, needed to address the key science questions of auroral plasma physics. The new knowledge that the mission will produce will find application in studies of the Sun, the processes that accelerate the solar wind and that produce aurora on other planets.
|
|
| 24. |
- Bhalerao, Rishikesh P, et al.
(författare)
-
Shoot-derived auxin is essential for early lateral root emergence in Arabidopsis seedlings
- 2002
-
Ingår i: The Plant Journal. - : Blackwell Publishing. - 0960-7412 .- 1365-313X. ; 29:3, s. 325-332
-
Tidskriftsartikel (refereegranskat)abstract
- Lateral root formation is profoundly affected by auxins. Here we present data which indicate that light influences the formation of indole-3-acetic acid (IAA) in germinating Arabidopsis seedlings. IAA transported from the developing leaves to the root system is detectable as a short-lived pulse in the roots and is required for the emergence of the lateral root primordia (LRP) during early seedling development. LRP emergence is inhibited by the removal of apical tissues prior to detection of the IAA pulse in the root, but this treatment has minimal effects on LRP initiation. Our results identify the first developing true leaves as the most likely source for the IAA required for the first emergence of the LRP, as removal of cotyledons has only a minor effect on LRP emergence in contrast to removal of the leaves. A basipetal IAA concentration gradient with high levels of IAA in the root tip appears to control LRP initiation, in contrast to their emergence. A significant increase in the ability of the root system to synthesize IAA is observed 10 days after germination, and this in turn is reflected in the reduced dependence of the lateral root emergence on aerial tissue-derived auxin at this stage. We propose a model for lateral root formation during early seedling development that can be divided into two phases: (i) an LRP initiation phase dependent on a root tip-localized IAA source, and (ii) an LRP emergence phase dependent on leaf-derived IAA up to 10 days after germination.
|
|
| 25. |
- Bolmsvik, Åsa, 1975-
(författare)
-
Structural-acoustic analysis of wall-to-floor joints in timber-framed housing
- 2009
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Even though a building meets the regulations with respect to impact sound, structures with wooden frames may receive complaints from the inhabitants due to structure-borne sound in the lower frequencies. In this thesis measuring methods that are more precise than the traditional measuring methods have been used to see if they could give a better knowledge about flanking transmission in the low frequencies in timber-framed structures. The measuring results have been compared to FE models of a complete room. By comparing the non-traditional measurement results with the results from the FE model a straight forward comparison could be made.Two field measurements have been made within the scope of this thesis. In the first field measurement a two-storey house with four apartments was studied. A traditional tapping machine was used as a source, and an accelerometer measured the responses in the apartment below. This study showed differences in acceleration levels on the surrounding surfaces in the room below the source. The non-bearing apartment-separating wall was the surface that had the largest acceleration levels. In the second field measurement several accelerometers were used simultaneously to measure the responses. With the help of experimental modal analysis and by measuring at several points at the same time the operational deflection shapes of all surrounding surfaces in the reception room could be captured. In this measurement a shaker was used as a source, so that the applied load could be measured the whole time. The load had constant level containing all frequencies within the studied frequency range. Simultaneously, a microphone was used and the acceleration levels in the surrounding surfaces could be compared to the sound pressure in the room. The measurements showed, not surprisingly, that at the frequency where the largest sound pressure was found all surrounding surfaces had acceleration peaks.An FE analysis of the room from the second field measurement has been made. The analysis shows that by using a load similar to the load used in the experiments the velocity level of the responses are in the same range both in the analysis and in the experiments. It also shows that damping has a large influence and that the damping needs to be studied further to be able to use the model as a prediction tool for flanking transmission.However, even though the results from the measurements and the analysis have some deviations, a great deal can be learned about the phenomenon of flanking transmission of timber-framed structures by using the proposed methods.
|
|
