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• 51.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Sjukgymnastik. Swedish Winter Sports Research Centre Mid Sweden; University Department of Health Sciences, Östersund, Sweden. MOX – Department of Mathematics, Politecnico di Milano. Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet, Statistik. Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. MOX – Department of Mathematics, Politecnico di Milano.
An inferential framework for domain selection in functional anova2014Ingår i: Contributions in infinite-dimensional statistics and related topics / [ed] Bongiorno, E.G., Salinelli, E., Goia, A., Vieu, P, Esculapio , 2014Konferensbidrag (Refereegranskat)

We present a procedure for performing an ANOVA test on functional data, including pairwise group comparisons. in a Scheff´e-like perspective. The test is based on the Interval Testing Procedure, and it selects intervals where the groups significantly differ. The procedure is applied on the 3D kinematic motion of the knee joint collected during a functional task (one leg hop) performed by three groups of individuals.

• 52.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi. Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet, Statistik. Department of Statistical Sciences, Università Cattolica del Sacro Cuore, Milan, Italy. Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering. Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet, Statistik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Nonparametric inference for functional-on-scalar linear models applied to knee kinematic hop data after injury of the anterior cruciate ligament2018Ingår i: Scandinavian Journal of Statistics, Vol. 45, nr 4, s. 1036-1061Artikel i tidskrift (Refereegranskat)

Motivated by the analysis of the dependence of knee movement patterns during functional tasks on subject-specific covariates, we introduce a distribution-free procedure for testing a functional-on-scalar linear model with fixed effects. The procedure does not only test the global hypothesis on the entire domain but also selects the intervals where statistically significant effects are detected. We prove that the proposed tests are provided with an asymptotic control of the intervalwise error rate, that is, the probability of falsely rejecting any interval of true null hypotheses. The procedure is applied to one-leg hop data from a study on anterior cruciate ligament injury. We compare knee kinematics of three groups of individuals (two injured groups with different treatments and one group of healthy controls), taking individual-specific covariates into account.

• 53.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet, Statistik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Multiresolution clustering of dependent functional data with application to climate reconstruction2019Ingår i: Stat, E-ISSN 2049-1573, Vol. 8, nr 1, artikel-id e240Artikel i tidskrift (Refereegranskat)

We propose a new nonparametric clustering method for dependent functional data, the double clustering bagging Voronoi method. It consists of two levels of clustering. Given a spatial lattice of points, a function is observed at each grid point. In the first‐level clustering, features of the functional data are clustered. The second‐level clustering takes dependence into account, by grouping local representatives, built from the resulting first‐level clusters, using a bagging Voronoi strategy. Depending on the distance measure used, features of the functions may be included in the second‐step clustering, making the method flexible and general. Combined with the clustering method, a multiresolution approach is proposed that searches for stable clusters at different spatial scales, aiming to capture latent structures. This provides a powerful and computationally efficient tool to cluster dependent functional data at different spatial scales, here illustrated by a simulation study. The introduced methodology is applied to varved lake sediment data, aiming to reconstruct winter climate regimes in northern Sweden at different time resolutions over the past 6,000 years.

• 54.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Multivariate piecewise linear interpolation of a random field2011Manuskript (preprint) (Övrigt vetenskapligt)

We consider a multivariate piecewise linear interpolation of a continuous random field on a-dimensional cube. The approximation performance is measured by the integrated mean square error. Multivariate piecewise linear interpolator is defined by N field observations on a locations grid (or design). We investigate the class of locally stationary random fields whose local behavior is like a fractional Brownian field in mean square sense and find the asymptotic approximation accuracy for a sequence of designs for large N. Moreover, for certain classes of continuous and continuously differentiable fields we provide the upper bound for the approximation accuracy in the uniform mean square norm.

• 55.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
On the error of the Monte Carlo pricing method for Asian option2008Ingår i: Journal of Numerical and Applied Mathematics, ISSN 0868-6912, Vol. 96, nr 1, s. 1-10Artikel i tidskrift (Refereegranskat)

We consider a Monte Carlo method to price a continuous arithmetic Asian option with a given precision. Piecewise constant approximation and plain simulation are used for a wide class of models based on L\'{e}vy processes. We give bounds of the possible discretization and simulation errors. The sufficient numbers of discretization points and simulations to obtain requested accuracy are derived. To demonstrate the general approach, the Black-Scholes model is studied in more detail. We undertake the case of continuous averaging and starting time zero,  but the obtained results can be applied to the discrete case  and generalized for any time before an execution date. Some numerical experiments and comparison to the PDE based method are also presented.

• 56.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Piecewise multilinear interpolation of a random field2013Ingår i: Advances in Applied Probability, ISSN 0001-8678, E-ISSN 1475-6064, Vol. 45, nr 4, s. 945-959Artikel i tidskrift (Refereegranskat)

We consider a piecewise-multilinear interpolation of a continuous random field on a d-dimensional cube. The approximation performance is measured using the integrated mean square error. Piecewise-multilinear interpolator is defined by N-field observations on a locations grid (or design). We investigate the class of locally stationary random fields whose local behavior is like a fractional Brownian field, in the mean square sense, and find the asymptotic approximation accuracy for a sequence of designs for large N. Moreover, for certain classes of continuous and continuously differentiable fields, we provide the upper bound for the approximation accuracy in the uniform mean square norm.

• 57.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Spline approximation of a random process with singularity2011Ingår i: Journal of Statistical Planning and Inference, ISSN 0378-3758, E-ISSN 1873-1171, Vol. 141, nr 3, s. 1333-1342Artikel i tidskrift (Refereegranskat)

Let a continuous random process X defined on [0,1] be (m+β)-smooth, 0m, 0<β$\leq$1, in quadratic mean for all t>0 and have an isolated singularity point at t=0. In addition, let X be locally like a m-fold integrated β-fractional Brownian motion for all nonsingular points. We consider approximation of X by piecewise Hermite interpolation splines with n free knots (i.e., a sampling design, a mesh). The approximation performance is measured by mean errors (e.g., integrated or maximal quadratic mean errors). We construct a sequence of sampling designs with asymptotic approximation rate n^(m+β) for the whole interval.

• 58.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Stratified Monte Carlo quadrature for continuous random fields2015Ingår i: Methodology and Computing in Applied Probability, ISSN 1387-5841, E-ISSN 1573-7713, Vol. 17, nr 1, s. 59-72Artikel i tidskrift (Refereegranskat)

We consider the problem of numerical approximation of integrals of random fields over a unit hypercube. We use a stratified Monte Carlo quadrature and measure the approximation performance by the mean squared error. The quadrature is defined by a finite number of stratified randomly chosen observations with the partition generated by a rectangular grid (or design). We study the class of locally stationary random fields whose local behavior is like a fractional Brownian field in the mean square sense and find the asymptotic approximation accuracy for a sequence of designs for large number of the observations. For the H¨older class of random functions, we provide an upper bound for the approximation error. Additionally, for a certain class of isotropic random functions with an isolated singularity at the origin, we construct a sequence of designs eliminating the effect of the singularity point.

• 59.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Politecnico di Milano, Italy. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Politecnico di Milano, Italy. Oslo University, Norway.
Clustering misaligned dependent curves applied to varved lake sediment for climate reconstruction2017Ingår i: Stochastic environmental research and risk assessment (Print), ISSN 1436-3240, E-ISSN 1436-3259, Vol. 31, nr 1, s. 71-85Artikel i tidskrift (Refereegranskat)

In this paper we introduce a novel functional clustering method, the Bagging Voronoi K-Medoid Aligment (BVKMA) algorithm, which simultaneously clusters and aligns spatially dependent curves. It is a nonparametric statistical method that does not rely on distributional or dependency structure assumptions. The method is motivated by and applied to varved (annually laminated) sediment data from lake Kassjön in northern Sweden, aiming to infer on past environmental and climate changes. The resulting clusters and their time dynamics show great potential for seasonal climate interpretation, in particular for winter climate changes.

• 60.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
Pojkar som skriver: En kvalitativ studie om vad som utmärker mer avancerade skrivare2017Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)

• 61.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
UHPLC-ESI/TOFMS Determination of Salicylate-like Phenolic Gycosides in Populus tremula Leaves2011Ingår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 37, nr 8, s. 857-70Artikel i tidskrift (Refereegranskat)

Associations of salicylate-like phenolic glycosides (PGs) with biological activity have been reported in Salix and Populus trees, but only for a few compounds, and in relation to a limited number of herbivores. By considering the full diversity of PGs, we may improve our ability to recognize genotypes or chemotype groups and enhance our understanding of their ecological function. Here, we present a fast and efficient general method for salicylate determination in leaves of Eurasian aspen that uses ultra-high performance liquid chromatography-electrospray ionization/time-of-flight mass spectrometry (UHPLC-ESI/TOFMS). The time required for the liquid chromatography separations was 13.5 min per sample, compared to around 60 min per sample for most HPLC protocols. In leaf samples from identical P. tremula genotypes with diverse propagation and treatment histories, we identified nine PGs. We found the compound-specific mass chromatograms to be more informative than the UV-visible chromatograms for compound identification and when quantitating samples with large variability in PG content. Signature compounds previously reported for P. tremoloides (tremulacin, tremuloidin, salicin, and salicortin) always were present, and five PGs (2'-O-cinnamoyl-salicortin, 2'-O-acetyl-salicortin, 2'-O-acetyl-salicin, acetyl-tremulacin, and salicyloyl-salicin) were detected for the first time in P. tremula. By using information about the formic acid adduct that appeared for PGs in the LTQ-Orbitrap MS environment, novel compounds like acetyl-tremulacin could be tentatively identified without the use of standards. The novel PGs were consistently either present in genotypes regardless of propagation and damage treatment or were not detectable. In some genotypes, concentrations of 2'-O-acetyl-salicortin and 2'-O-cinnamoyl-salicortin were similar to levels of biologically active PGs in other Salicaceous trees. Our study suggests that we may expect a wide variation in PG content in aspen populations which is of interest both for studies of interactions with herbivores and for mapping population structure.

• 62.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Effectof Growth Time, Growth Temperature and Light  on Growth Mechanism of C60 nanorods2013Självständigt arbete på avancerad nivå (masterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)

In this thesis work C60 nanorods were produced by Liquid-Liquid Interfacial Precipitation method (LLIP) assisted with 10 s of weak sonication. Ethanol and m-dichlorobenzene were used as poor and good solvents of C60, respectively. Five different temperatures, 4, 10, 20, 30, 40 and 50                         , were chosen as growth temperatures of different samples to investigate the effect of temperature on the grown structures. Different samples were prepared in the dark and under the light with various growth time to determine the effect of light and growth time on growth of C60 nanorods. The characterization of the grown C60 nanorods were conducted by transmission electron microscopy (TEM) and x-ray diffraction (XRD). The result of characterization indicated that the sonication introduced smaller C60 nanostructures; light irradiation and temperature increase (till 40 C0) during the growth time resulted in nanorods with smaller diameter, whereas the long growth time lead to the increase of the diameter of C60 nanorods. The as-grown C60 nanorods synthesized at different conditions possess an hcp crystal structure.

• 63.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Measuring the efficiency and charge carrier mobility of organic solar cells2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)

P3HT single layer, P3HT/PCBM bilayer and P3HT/PCBM inverted bilayer devices were produced by spin coating organic layers onto ITO patterned glass in air, and clamping it with an Au coated silicon wafer, as top electrode, at the end (Figure13). Normal and inverted bilayer devices were also fabricated with and without PEDOT:PSS. All devices were divided into two groups by changing concentration of P3HT solution. The first group of devices contained 1.0 wt. % P3HT solution (P3HT in dichlorobenzene); the second group 0.56wt %. Power conversion efficiency, short circuit current, open circuit voltage, fill factor and maximum extracted power were measured on all produced devices.

In contrast, all devices with 1.0wt % P3HT concentration showed better result than the devices with 0.56wt %. The highest result was obtained for P3HT single layer devices in both cases with short circuit current 56uA/cm2, open circuit voltage 0.94mV, maximum power 11.4uW/cm2 and power conversion efficiency of 0.11%. Inverted bilayer devices performed better than the non-inverted one. The devices with PEDOT:PSS got slightly better performance than the non-PEDOT:PSS used one.

Charge carrier mobility measurement was done for all fabricated devices with charge extraction by linearly increasing voltage (CELIV) and dark injected space charge limited current (DI-SCLC) methods. All devices showed same magnitude of charge carrier mobility 10-5 cm2/V.s, the highest value still belongs to P3HT single layer device. The charge carrier mobility in all devices observed by DI-SCLC technique is one order of magnitude higher than by CELIV technique. This may be due to DI-SCLC method`s restriction on ohmic contacts between material and electrode.

• 64.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
Understanding Web Users Behaviour From A Web Video Camera2003Rapport (Övrigt vetenskapligt)

To develop a Real-Time system, which can capture and track the web user’s head motion. Based on the head motion information, the system should be able to identify whether the user is interested in the current homepage or not. A future system property would be to find out in which area of the homepage the user’s interest is moving.

• 65. Accinelli, Cesare
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Removal of oseltamivir (Tamiflu) and other selected pharmaceuticals from wastewater using a granular bioplastic formulation entrapping propagules of Phanerochaete chrysosporium2010Ingår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 81, nr 3, s. 436-43Artikel i tidskrift (Refereegranskat)

The capacity of the ligninolytic fungus Phanerochaete chrysosporium to degrade a wide variety of environmentally persistent xenobiotics has been largely reported in the literature. Beside other factors, one barrier to a wider use of this bioremediation fungus is the availability of effective formulations that ensure easy preparation, handling and application. In this series of laboratory experiments, we evaluated the efficiency of a granular bioplastic formulation entrapping propagules of P. chrysosporium for removal of four selected pharmaceuticals from wastewater samples. Addition of inoculated granules to samples of the wastewater treatment plant of Bologna significantly increased the removal of the antiviral drug oseltamivir (Tamiflu), and the antibiotics, erythromycin, sulfamethoxazol, and ciprofloxacin. Similar effects were also observed in effluent water. Oseltamivir was the most persistent of the four active substances. After 30d of incubation, approximately two times more oseltamivir was removed in bioremediated wastewater than controls. The highest removal efficiency of the bioplastic formulation was observed with the antibiotic ciprofloxacin. Microbiological DNA-based analysis showed that the bioplastic matrix supported the growth of P. chrysosporium, thus facilitating its adaptation to unusual environment such as wastewater.

• 66. Accinelli, Cesare
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Dissipation and removal of oseltamivir (Tamiflu) in different aquatic environments2010Ingår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 79, nr 8, s. 891-897Artikel i tidskrift (Refereegranskat)

The antiviral drug oseltamivir (Tamiflu) has received recent attention due to the potential use as a first-line defense against H5N1 and H1N1 influenza viruses. Research has shown that oseltamivir is not removed during conventional wastewater treatments, thus having the potential to enter surface water bodies. A series of laboratory experiments investigated the fate and the removal of oseltamivir in two surface water ecosystems of Japan and in a municipal wastewater treatment plant located in Northern Italy. Persistence of oseltamivir in surface water ranged from non-detectable degradation to a half-life of 53d. After 40d, <3% of radiolabeled oseltamivir evolved as (14)CO(2). The presence of sediments (5%) led to a significant increase of oseltamivir degradation and mineralization rates. A more intense mineralization was observed in samples of the wastewater treatment plant when applying a long incubation period (40d). More precisely, 76% and 37% of the initial radioactivity applied as (14)C-oseltamivir was recovered as (14)CO(2) from samples of the biological tank and effluent water, respectively. Two bacterial strains growing on oseltamivir as sole carbon source were isolated and used for its removal from synthetic medium and environmental samples, including surface water and wastewater. Inoculation of water and wastewater samples with the two oseltamivir-degrading strains showed that mineralization of oseltamivir was significantly higher in both inoculated water and wastewater, than in uninoculated controls. Denaturing gradient gel electrophoresis and quantitative PCR analysis showed that Tamiflu would not affect the microbial population of surface water and wastewater.

• 67. Acharya, Shravan S.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. School of Chemistry, Monash University, Clayton, Australia.
Diverse composites of metal-complexes and PEDOT facilitated by metal-free vapour phase polymerization2017Ingår i: Reactive & functional polymers, ISSN 1381-5148, E-ISSN 1873-166X, Vol. 116, s. 101-106Artikel i tidskrift (Refereegranskat)

Abstract Oxidative polymerization for the manufacture of conducting polymers such as poly(3,4-ethylenedioxy-thiophene) has traditionally employed iron(III) salts. Demonstrated in this study is vapour phase polymerization of 3,4-ethylenedio- xythiophene using a metal-free oxidant, ammonium persulfate, leading to films with an estimated conductivity of 75 S/cm. Additionally, a route for embedding active transition metal complexes into these poly(3,4-ethylenedioxythiophene)/-poly(styrene-4-sulfonate) (PEDOT/PSS) films via vapour assisted complexation is outlined. Here, the vapour pressure of solid ligands around their melting temperatures was exploited to ensure complexation to metal ions added into the oxidant mixture prior to polymerization of PEDOT. Four composite systems are discussed, viz. PEDOT/PSS embedded with tris(8-hydroxyquinolinato)cobalt(III), tris(2,2-bipyridine)cobalt(II), tris(1,10- phenanthroline)cobalt(II) and tris(8-hyd-roxyquinolinato)aluminium(III). Using these composites, electrochemical reduction of nitrite to ammonia with a faradaic efficiency of 61% was reported.

• 68. Acharya, Shravan
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Rates of water exchange in 2,2'-bipyridine and 1,10-phenanthroline complexes of CoII and MnII2017Ingår i: Australian journal of chemistry (Print), ISSN 0004-9425, E-ISSN 1445-0038, Vol. 70, nr 6, s. 751-754Artikel i tidskrift (Refereegranskat)

The rates and activation parameters of water exchange at pH 3.0 have been determined using variable temperature 17O NMR spectroscopy for four CoII complexes and one MnII complex: [Co(bpy)(H2O)4]2+, [Co(bpy)2 (H2O)2]2+, [Co(phen)-(H2O)4]2+, [Co(phen)2 (H2O)2]2+, and [Mn(bpy)(H2O)4]2+ (bpy = 2,2′-bipyridyl and phen = 1,10-phenanthroline). Substitution of aquo ligands with 1,10-phenanthroline or 2,2′-bipyridyl leads to an increase in the rate of exchange in the manganese complexes, from k298 (1.8 ± 0.1) × 107 s-1 for [Mn(H2O)6]2+ to (7.2 ± 0.3) × 107 s-1 for [Mn(phen)2 (H2O)2]2+, whereas the trends are more complex for the cobalt complexes. We have used the new data in conjunction with literature data for similar complexes to analyse the effect of M–OH2 distance and degree of substitution.

• 69.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Arkitekthögskolan vid Umeå universitet.
Sequence Lane: De-centralization of the social arena in the modern city plan2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)

Reconstruction and densification of Gamla storgatan in Holmsund.

Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
Chloroplast and mitochondrial proteases in Arabidopsis: a proposed nomenclature2001Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 125, nr 4, s. 1912-1918Artikel i tidskrift (Refereegranskat)

The identity and scope of chloroplast and mitochondrial proteases in higher plants has only started to become apparent in recent years. Biochemical and molecular studies suggested the existence of Clp, FtsH, and DegP proteases in chloroplasts, and a Lon protease in mitochondria, although currently the full extent of their role in organellar biogenesis and function remains poorly understood. Rapidly accumulating DNA sequence data, especially from Arabidopsis, has revealed that these proteolytic enzymes are found in plant cells in multiple isomeric forms. As a consequence, a systematic approach was taken to catalog all these isomers, to predict their intracellular location and putative processing sites, and to propose a standard nomenclature to avoid confusion and facilitate scientific communication. For the Clp protease most of the ClpP isomers are found in chloroplasts, whereas one is mitochondrial. Of the ATPase subunits, the one ClpD and two ClpC isomers are located in chloroplasts, whereas both ClpX isomers are present in mitochondria. Isomers of the Lon protease are predicted in both compartments, as are the different forms of FtsH protease. DegP, the least characterized protease in plant cells, has the most number of isomers and they are predicted to localize in several cell compartments. These predictions, along with the proposed nomenclature, will serve as a framework for future studies of all four families of proteases and their individual isomers.

• 71.
Institute of Mathematics of the Polish Academy of Sciences, Warsaw, Poland.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
The boundary Harnack inequality for variable exponent p-Laplacian, Carleson estimates, barrier functions and p(⋅)-harmonic measures2016Ingår i: Annali di Matematica Pura ed Applicata, ISSN 0373-3114, E-ISSN 1618-1891, Vol. 195, nr 2, s. 623-658Artikel i tidskrift (Refereegranskat)

We investigate various boundary decay estimates for p(⋅)-harmonic functions. For domains in Rn,n≥2satisfying the ball condition (C1,1-domains), we show the boundary Harnack inequality for p(⋅)-harmonic functions under the assumption that the variable exponent p is a bounded Lipschitz function. The proof involves barrier functions and chaining arguments. Moreover, we prove a Carleson-type estimate for p(⋅)-harmonic functions in NTA domains in Rn and provide lower and upper growth estimates and a doubling property for a p(⋅)-harmonic measure.

Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
What is the Word for Engineering in Swedish: Swedish Students' Conceptions of their Discipline2007Rapport (Övrigt vetenskapligt)
• 73.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Alpha-actinin - an amazing journey through time and species2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)

In eukaryotes, the actin cytoskeleton plays an important role in a large variety of cellular events. Its reorganization is regulated by a plethora of actin-modulating proteins, such as α-actinin.

α-actinin is a ubiquitous actin-binding protein that belongs to the spectrin superfamily. This family, besides α-actinin, includes spectrin, dystrophin and utrophin. Phylogenetic analyses have indicated that the family members arose after several intragene duplications and rearrangements of a common ancestral α-actinin isoform. Up to the invertebrate-vertebrate bifurcation, organisms seemed to have a single, calcium-dependent α‑actinin. After the split, invertebrates have kept this single isoform, in contrast to vertebrates that acquired four distinct isoforms. Of the four vertebrate α-actinin isoforms, the two present in non-muscle cells are typically calcium sensitive while the two muscle isoforms are calcium insensitive.

α-actinin in higher organisms is characterized by the presence of three distinct structural domains: a highly conserved N-terminal actin-binding domain, a central rod domain with four spectrin repeats and a calcium-binding C terminus with EF-hand motifs. In some primitive organisms, such as protozoa and fungi, the rod domain of α-actinin contains only one or two spectrin repeats. With the completion of an ever increasing number of genomes, new and atypical α‑actinin sequences had been available that have not been characterized yet. To obtain a firmer understanding of the evolutionary history of α-actinin, the main objective of this study was to identify, purify and biochemically characterize atypical α‑actinin or α‑actinin-like proteins of the parasite Entamoeba histolytica and of the fungus Schizosaccharomyces pombe. Our results show that both isoforms, despite the much shorter rod domain, are able to bind and cross-link actin filaments and therefore can be considered genuine α-actinins.

• 74.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Alpha-actinin of Schizosaccharomyces pombeManuskript (preprint) (Övrigt vetenskapligt)
• 75.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
The domain structure of Entamoeba α-actinin22010Ingår i: Cellular & Molecular Biology Letters (Druk), ISSN 1425-8153, E-ISSN 1689-1392, Vol. 15, nr 4, s. 665-78Artikel i tidskrift (Refereegranskat)

Entamoeba histolytica, a major agent of human amoebiasis, expresses two distinct forms of α-actinin, a ubiquitous actin-binding protein that is present in most eukaryotic organisms. In contrast to all metazoan α-actinins, in both isoforms the intervening rod domain that connects the N-terminal actin-binding domain with the C-terminal EF-hands is much shorter. It is suggested that these α-actinins may be involved in amoeboid motility and phagocytosis, so we cloned and characterised each domain of one of these α-actinins to better understand their functional role. The results clearly showed that the domains have properties very similar to those of conventional α-actinins.

• 76.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Crystallization and preliminary X-ray analysis of the Entamoeba histolytica α-actinin-2 rod domain2011Ingår i: Acta Crystallographica. Section F: Structural Biology and Crystallization Communications, ISSN 1744-3091, E-ISSN 1744-3091, Vol. 67, nr 10, s. 1214-1217Artikel i tidskrift (Refereegranskat)

-Actinins form antiparallel homodimers that are able to cross-link actin filaments. The protein contains three domains: an N-terminal actin-binding domain followed by a central rod domain and a calmodulin-like EF-hand domain at the C-terminus. Here, crystallization of the rod domain of Entamoeba histolytica -actinin-2 is reported; it crystallized in space group P212121, with unit-cell parameters a = 47.8, b = 79.1, c = 141.8 Å. A Matthews coefficient VM of 2.6 Å3 Da-1 suggests that there are two molecules and 52.5% solvent content in the asymmetric unit. A complete native data set extending to a d-spacing of 2.8 Å was collected on beamline I911-2 at MAX-lab, Sweden.

Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Characterisation of Schizosaccharomyces pombe alpha-actinin2016Ingår i: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 4, artikel-id e1858Artikel i tidskrift (Refereegranskat)

The actin cytoskeleton plays a fundamental role in eukaryotic cells. Its reorganization is regulated by a plethora of actin-modulating proteins, such as a-actinin. In higher organisms, alpha-actinin is characterized by the presence of three distinct structural domains: an N-terminal actin-binding domain and a C-terminal region with EF-hand motif separated by a central rod domain with four spectrin repeats. Sequence analysis has revealed that the central rod domain of alpha-actinin from the fission yeast Schizosaccharomyces pombe consists of only two spectrin repeats. To obtain a firmer understanding of the structure and function of this unconventional alpha-actinin, we have cloned and characterized each structural domain. Our results show that this alpha-actinin isoform is capable of forming dimers and that the rod domain is required for this. However, its actin-binding and cross-linking activity appears less efficient compared to conventional alpha-actinins. The solved crystal structure of the actin-binding domain indicates that the closed state is stabilised by hydrogen bonds and a salt bridge not present in other a-actinins, which may reduce the affinity for actin.

Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
Ion and Solvent Dynamics in Gel Electrolytes Based on Ethylene Oxide Grafted Acrylate Polymers2002Ingår i: The Journal of Physical Chemistry B, Vol. 106, nr 47, s. 12119-12123Artikel i tidskrift (Refereegranskat)

Multinuclear pulsed field gradient NMR measurements and rheological viscosity measurements were performed on three series of polymer gel electrolytes. The gels were based on a lithium salt electrolyte swollen into a copolymer matrix comprising an acrylate backbone and ethylene oxide side chains. In each series the side chains differed in length and number, but the acrylate-to-ethylene oxide ratio was kept constant. It was found that the self-diffusion coefficient of the cations was much lower than that of the anions, and that it decreased rapidly when the side chains got longer. In contrast, the self-diffusion coefficient of the anions was found to be independent of chain length. In the gel electrolytes, the diffusion coefficients of the solvent molecules are relatively constant despite an increased viscosity with increasing length of the side chains. However, in salt-free gels made for comparison, the diffusion coefficients of the solvent molecules decreased with increasing length of the side chains, which is consistent with an increased viscosity.

• 79.
Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506, USA.
Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506, USA. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education of China, Department of Energy and Power Engineering, Tsinghua University, Beijing, China. Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia, USA.
Effect of surface friction on ultrafast flame acceleration in obstructed cylindrical pipes2019Ingår i: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 9, nr 3, artikel-id 035249Artikel i tidskrift (Refereegranskat)

The Bychkov model of ultrafast flame acceleration in obstructed tubes [Valiev et al., “Flame Acceleration in Channels with Obstacles in the Deflagration-to-Detonation Transition,” Combust. Flame 157, 1012 (2010)] employed a number of simplifying assumptions, including those of free-slip and adiabatic surfaces of the obstacles and of the tube wall. In the present work, the influence of free-slip/non-slip surface conditions on the flame dynamics in a cylindrical tube of radius R, involving an array of parallel, tightly-spaced obstacles of size αR, is scrutinized by means of the computational simulations of the axisymmetric fully-compressible gasdynamics and combustion equations with an Arrhenius chemical kinetics. Specifically, non-slip and free-slip surfaces are compared for the blockage ratio, α, and the spacing between the obstacles, ΔZ, in the ranges 1/3 ≤ α ≤ 2/3 and 0.25 ≤ ΔZ/R ≤ 2.0, respectively.

For these parameters, an impact of surface friction on flameacceleration is shown to be minor, only 1-4%, slightly facilitating acceleration in a tube with ΔZ/R = 0.5 and moderating acceleration in thecase of ΔZ/R = 0.25. Given the fact that the physical boundary conditions are non-slip as far as the continuum assumption is valid, the presentwork thereby justifies the Bychkov model, employing the free-slip conditions, and makes its wider applicable to the practical reality. Whilethis result can be anticipated and explained by a fact that flame propagation is mainly driven by its spreading in the unobstructed portion ofan obstructed tube (i.e. far from the tube wall), the situation is, however, qualitatively different from that in the unobstructed tubes, wheresurface friction modifies the flame dynamics conceptually.

• 80.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Microbial Biosynthesis of Thiol Compounds: Implications for Speciation, Cellular Uptake, and Methylation of Hg(II)2019Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 53, nr 14, s. 8187-8196Artikel i tidskrift (Refereegranskat)

Cellular uptake of inorganic divalent mercury (Hg(II)) is a key step in microbial formation of neurotoxic methylmercury (MeHg), but the mechanisms remain largely unidentified. We show that the iron reducing bacterium Geobacter sulfurreducens produces and exports appreciable amounts of low molecular mass thiol (LMM-RSH) compounds reaching concentrations of about 100 nM in the assay medium. These compounds largely control the chemical speciation and bioavailability of Hg(II) by the formation of Hg(LMM-RS)<INF><INF><INF>2</INF></INF> </INF>complexes (primarily with cysteine) in assays without added thiols. By characterizing these effects, we show that the thermodynamic stability of Hg(II)-complexes is a principal controlling factor for Hg(II) methylation by this bacterium such that less stable complexes with mixed ligation involving LMM-RSH, OH-, and Cl- are methylated at higher rates than the more stable Hg(LMM-RS)<INF>2</INF> complexes. The Hg(II) methylation rate across different Hg(LMM-RS)<INF>2</INF> compounds is also influenced by the chemical structure of the complexes. In contrast to the current perception of microbial uptake of Hg, our results adhere to generalized theories for metal biouptake based on metal complexation with cell surface ligands and refine the mechanistic understanding of Hg(II) availability for microbial methylation.

Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
Ion-beam driven dust ion-acoustic solitary waves in dusty plasmas2010Ingår i: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 17, nr 4, artikel-id 044502Artikel i tidskrift (Refereegranskat)

The nonlinear propagation of small but finite amplitude dust ion-acoustic waves (DIAWs) in an ion-beam driven plasma consisting of Boltzmannian electrons, positive ions, and stationary negatively charged dust grains is studied by using the standard reductive perturbation technique. It is shown that there exist two critical values (γc1) and (γc2) of ion beam to ion phase velocity ratio (γ), above and below which the beam generated solitons are not possible. The effects of the parameters, namely, γ, the ratio of the ion beam to plasma ion density (μi), the dust to ion density ratio (μd), and the ion beam to plasma ion mass ratio (μ) on both the amplitude and width of the stationary DIAWs, are analyzed numerically, and applications of the results to laboratory ion beam as well as space plasmas (e.g., auroral plasmas) are explained.

• 82.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Designhögskolan vid Umeå universitet.
Composing the Umeå pantry: a platform for dialogue on food production and human survival2015Ingår i: Participatory Innovation Conference, PIN-C / [ed] Rianne Valkenburg, Coen Dekkers, Janneke Sluijs, The Hague, 2015, Vol. 1, s. 83-90Konferensbidrag (Refereegranskat)

The Umeå Pantry was a five-week long public art event held in Umeå, Sweden, aimed at making concerns about food production public and supporting local communities interested in food related practices.

The event consisted of a series of performances where participant communities were invited to a dialogue on food concerns and practices in the region. The performances took the form of communal activities such as food harvesting, cooking, workshops, debates and demonstrations.

The making of the art event highlights the practice of creating forms for engagement and participation of disparate communities around social issues.

In the broader picture, this project contributes to the understanding of community participatory design and design for social innovation.

• 83.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Designhögskolan vid Umeå universitet.
Open-collaborative libraries: Libraries as generative community centres2015Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
• 84.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Designhögskolan vid Umeå universitet.
Prototyping boundary objects: Boundary objects as means for negotiating a cultural imaginary2015Konferensbidrag (Övrigt vetenskapligt)
• 85.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Designhögskolan vid Umeå universitet.
The Ability To Make A Difference In Participatory Design Projects2017Konferensbidrag (Refereegranskat)

The case study presented here is an intensive nine day community participation project in a Swiss town, aimed at fostering community food production. The approach to participatory design presented here seeks to emphasize the in-situ improvisatory ‘doing' of collaborative activities.

Using notions such as diffusing, reifying and catalyzing the study describes the iterative movement of the project that is bound up in material arrangements and social relations.

Through a reflection in action approach, the author unpacks how the designer's agency is understood through social interactions and acts of summarizing, materialization and translation.

The paper concludes by discussing power and agency, both as an outcome and central to the design process. This reflective exploration through the lens of agency seeks to encourage the reflexivity of designers in collaborative practice.

Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
Predation on black flies (Diptera: Simuliidae) by the carnivorous plant Pinguicula vulgaris (Lentibulariaceae) in northern Sweden2004Ingår i: Entomologica Fennica, ISSN 0785-8760, Vol. 15, s. 124-128Artikel i tidskrift (Refereegranskat)
• 87.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Parallel Algorithms and Library Software for the Generalized Eigenvalue Problem on Distributed Memory Computer Systems2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)

We present and discuss algorithms and library software for solving the generalized non-symmetric eigenvalue problem (GNEP) on high performance computing (HPC) platforms with distributed memory. Such problems occur frequently in computational science and engineering, and our contributions make it possible to solve GNEPs fast and accurate in parallel using state-of-the-art HPC systems. A generalized eigenvalue problem corresponds to finding scalars y and vectors x such that Ax = yBx, where A and B are real square matrices. A nonzero x that satisfies the GNEP equation is called an eigenvector of the ordered pair (A,B), and the scalar y is the associated eigenvalue. Our contributions include parallel algorithms for transforming a matrix pair (A,B) to a generalized Schur form (S,T), where S is quasi upper triangular and T is upper triangular. The eigenvalues are revealed from the diagonals of S and T. Moreover, for a specified set of eigenvalues an associated pair of deflating subspaces can be computed, which typically is requested in various applications. In the first stage the matrix pair (A,B) is reduced to a Hessenberg-triangular form (H,T), where H is upper triangular with one nonzero subdiagonal and T is upper triangular, in a finite number of steps. The second stage reduces the matrix pair further to generalized Schur form (S,T) using an iterative QZ-based method. Outgoing from a one-stage method for the reduction from (A,B) to (H,T), a novel parallel algorithm is developed. In brief, a delayed update technique is applied to several partial steps, involving low level operations, before associated accumulated transformations are applied in a blocked fashion which together with a wave-front task scheduler makes the algorithm scale when running in a parallel setting. The potential presence of infinite eigenvalues makes a generalized eigenvalue problem ill-conditioned. Therefore the parallel algorithm for the second stage, reduction to (S,T) form, continuously scan for and robustly deflate infinite eigenvalues. This will reduce the impact so that they do not interfere with other real eigenvalues or are misinterpreted as real eigenvalues. In addition, our parallel iterative QZ-based algorithm makes use of multiple implicit shifts and an aggressive early deflation (AED) technique, which radically speeds up the convergence. The multi-shift strategy is based on independent chains of so called coupled bulges and computational windows which is an important source of making the algorithm scalable. The parallel algorithms have been implemented in state-of-the-art library software. The performance is demonstrated and evaluated using up to 1600 CPU cores for problems with matrices as large as 100000 x 100000. Our library software is described in a User Guide. The software is, optionally, tunable via a set of parameters for various thresholds and buffer sizes etc. These parameters are discussed, and recommended values are specified which should result in reasonable performance on HPC systems similar to the ones we have been running on.

• 88.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Distributed one-stage Hessenberg-triangular reduction with wavefront scheduling2018Ingår i: SIAM Journal on Scientific Computing, ISSN 1064-8275, E-ISSN 1095-7197, Vol. 40, nr 2, s. C157-C180Artikel i tidskrift (Refereegranskat)

A novel parallel formulation of Hessenberg-triangular reduction of a regular matrix pair on distributed memory computers is presented. The formulation is based on a sequential cacheblocked algorithm by K degrees agstrom et al. [BIT, 48 (2008), pp. 563 584]. A static scheduling algorithm is proposed that addresses the problem of underutilized processes caused by two-sided updates of matrix pairs based on sequences of rotations. Experiments using up to 961 processes demonstrate that the new formulation is an improvement of the state of the art and also identify factors that limit its scalability.

• 89.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Distributed one-stage Hessenberg-triangular reduction with wavefront scheduling2016Rapport (Övrigt vetenskapligt)

A novel parallel formulation of Hessenberg-triangular reduction of a regular matrix pair on distributed memory computers is presented. The formulation is based on a sequential cache-blocked algorithm by Kågstrom, Kressner, E.S. Quintana-Ortí, and G. Quintana-Ortí (2008). A static scheduling algorithm is proposed that addresses the problem of underutilized processes caused by two-sided updates of matrix pairs based on sequences of rotations. Experiments using up to 961 processes demonstrate that the new algorithm is an improvement of the state of the art but also identifies factors that currently limit its scalability.

• 90.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
A parallel QZ algorithm for distributed memory HPC systems2014Ingår i: SIAM Journal on Scientific Computing, ISSN 1064-8275, E-ISSN 1095-7197, Vol. 36, nr 5, s. C480-C503Artikel i tidskrift (Refereegranskat)

Appearing frequently in applications, generalized eigenvalue problems represent one of the core problems in numerical linear algebra. The QZ algorithm of Moler and Stewart is the most widely used algorithm for addressing such problems. Despite its importance, little attention has been paid to the parallelization of the QZ algorithm. The purpose of this work is to fill this gap. We propose a parallelization of the QZ algorithm that incorporates all modern ingredients of dense eigensolvers, such as multishift and aggressive early deflation techniques. To deal with (possibly many) infinite eigenvalues, a new parallel deflation strategy is developed. Numerical experiments for several random and application examples demonstrate the effectiveness of our algorithm on two different distributed memory HPC systems.

• 91.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Parallel Variants of the Multishift QZ Algorithm with Advanced Deflation Techniques2007Ingår i: Applied Parallel Computing - State of the Art in Scientific Computing: 8th International Workshop, PARA 2006, Springer , 2007, s. 117-126Konferensbidrag (Refereegranskat)

The QZ algorithm reduces a regular matrix pair to generalized Schur form, which can be used to address the generalized eigenvalue problem. This paper summarizes recent work on improving the performance of the QZ algorithm on serial machines and work in progress on a novel parallel implementation. In both cases, the QZ iterations are based on chasing chains of tiny bulges. This allows to formulate the majority of the computation in terms of matrix-matrix multiplications, resulting in natural parallelism and better performance on modern computing systems with memory hierarchies. In addition, advanced deflation strategies are used, specifically the so called aggressive early deflation, leading to a considerable convergence acceleration and consequently to a reduction of floating point operations and computing time.

• 92.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N). SB–MATHICSE–ANCHP, EPF Lausanne.
PDHGEQZ user guide2015Rapport (Övrigt vetenskapligt)

Given a general matrix pair (A,B) with real entries, we provide software routines for computing a generalized Schur decomposition (S, T). The real and complex conjugate pairs of eigenvalues appear as 1×1 and 2×2 blocks, respectively, along the diagonals of (S, T) and can be reordered in any order. Typically, this functionality is used to compute orthogonal bases for a pair of deflating subspaces corresponding to a selected set of eigenvalues. The routines are written in Fortran 90 and targets distributed memory machines.

Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Fine Tuning the Optoelectronic Properties of Triphenylamine Based Donor Molecules for Organic Solar Cells2017Ingår i: Zeitschrift fur physikalische Chemie (Munchen. 1991), ISSN 0942-9352, Vol. 231, nr 6, s. 1127-1139Artikel i tidskrift (Refereegranskat)

Geometrical parameters, electronic structures and photophysical properties of three new triphenylamine (TPA) and diphenylamine (DPA) based electron donor materials M1-M3 (for organic solar cells) have been investigated through density functional theory (DFT) methods at the B3LYP/6-31G(d) level of the theory. TPA and DPA are used as donor moieties due to their electron donating ability while benzothiazole, cyanide and cyanomethylacetate (CMA) moieties have been taken as acceptor moieties. The time dependent-DFT (TD-DFT) method has been employed [TD-B3LYP/6-31G (d)] for the computation of excited state properties in the gas phase and in solvent (chloroform). The polarization continuum model is applied for calculations in the solvent phase. The designed molecules exhibited broad absorption in the visible and near infra-red region of spectrum with respect to a reference molecule "R" of a similar class of compounds. Based on reorganization energies calculations, these materials could act as excellent hole transport materials.

Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
The sedimentary and remote-sensing reflection of biomass burning in Europe2018Ingår i: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 27, nr 2, s. 199-212Artikel i tidskrift (Refereegranskat)

Aim: We provide the first European-scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire-regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10-500 mu m) and macroscopic charcoal (MAC from sieves, particles > 100 mu m). Location: North-south and east-west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period: Lake sediments and MODIS active fire and burned area products were collected for the years 2012-2015. Methods: Cylinder sediment traps were installed in lakes to annually collect charcoal particles in sediments. We quantitatively assessed the relationships between MIC and MAC influx (particles/cm(2)/year) and the MODIS-derived products to identify source areas of charcoal and the extent to which lake-sediment charcoal is linked to fire parameters across the continent. Results: Source area of sedimentary charcoal was estimated to a 40-km radius around sites for both MIC and MAC particles. Fires occurred in grasslands and in forests, with grass morphotypes of MAC accurately reflecting the burned fuel-type. Despite the lack of local fires around the sites, MAC influx levels reached those reported for local fires. Both MIC and MAC showed strong and highly significant relationships with the MODIS-derived fire parameters, as well as with climatic variation along a latitudinal temperature gradient. Main conclusions: MIC and MAC are suited to quantitatively reconstructing fire number and fire intensity on a regional scale. However, burned area may only be estimated using MAC. Local fires may be identified by using several lines of evidence, e.g. analysis of large particles (> 600 mu m), magnetic susceptibility and sedimentological data. Our results offer new insights and applications to quantitatively reconstruct fires and to interpret available sedimentary charcoal records.

• 95.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
Estimation methods for Asian Quanto Basket options2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)

All financial institutions that provide options to counterparties will in most cases get involved withMonte Carlo simulations. Options with a payoff function that depends on asset’s value at differenttime points over its lifespan are so called path dependent options. This path dependency impli-cates that there exists no parametric solution and the price must hence be estimated, it is hereMonte Carlo methods come into the picture. The problem though with this fundamental optionpricing method is the computational time. Prices fluctuate continuously on the open market withrespect to different risk factors and since it’s impossible to re-evaluate the option for all shifts dueto its computing intensive nature, estimations of the option price must be used. Estimating theprice from known points will of course never produce the same result as a full re-evaluation but anestimation method that produces reliable results and greatly reduces computing time is desirable.This thesis will evaluate different approaches and try to minimize the estimation error with respectto a certain number of risk factors.This is the background for our master thesis at Swedbank. The goal is to create multiple estima-tion methods and compare them to Swedbank’s current estimation model. By doing this we couldpotentially provide Swedbank with improvement ideas regarding some of its option products andrisk measurements. This thesis is primarily based on two estimation methods that estimate optionprices with respect to two variable risk factors, the value of the underlying assets and volatility.The first method is a grid that uses a second order Taylor expansion and the sensitivities delta,gamma and vega. The other method uses a grid of pre-simulated option prices for different shiftsin risk factors. The interpolation technique that is used in this method is calledPiecewise CubicHermiteinterpolation. The methods (or referred to as approaches in the report) are implementedto handle a relative change of 50 percent in the underlying asset’s index value, which is the firstrisk factor. Concerning the second risk factor, volatility, both methods estimate prices for a 50percent relative downward change and an upward change of 400 percent from the initial volatility.Should there emerge even more extreme market conditions both methods use linear extrapolationto estimate a new option price.

• 96.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
Attityder till naturvetenskap: Förändringar av flickors och pojkars attityder till biologi, fysik och kemi 1995 till 20072011Licentiatavhandling, monografi (Övrigt vetenskapligt)

I den här avhandlingen beskrivs hur hög- och lågpresterande flickors och pojkars attityder till biologi, fysik och kemi har förändrats från 1995 till 2007. Data från den svenska delen av TIMSS-studierna för årskurs 8 i Sverige används. För att definiera hög- och lågpresterande används resultatet på matematikprovet från TIMSS och attityderna undersöks med hjälp av fyra frågor från elevenkäterna. Resultatet diskuteras utifrån olika perspektiv som kan bidra till förståelsen av den komplexa bilden av olika faktorers betydelse för elevers attityder till naturvetenskap.

Det första resultatet, pojkar är mer positiva till fysik och kemi och flickor till biologi, diskuteras utifrån ämnenas genuskodning. På ett symboliskt plan är fysik och kemi mer förknippade med maskulinitet än biologi.

Det andra resultatet, högpresterande elever och särskilt pojkar, är mindre positiva till de tre ämnena 2007 än 1995. Det resultatet diskuteras mot bakgrund av ungdomars identitet och identitetskonstruktion. Det verkar som om unga människor i dag inte tycker att utbildningar och arbeten inom det naturvetenskapliga och tekniska området ger dem möjligheter att använda sina talanger, kreativitet och självförverkligande. Resultatet diskuteras också utifrån de förändringar av arbetsmetoder som har skett i svensk skola där det individuella arbetet har ökat och lärarledda genomgångar har minskat. Kan det ha påverkat de högpresterande eleverna så att de har blivit mindre stimulerade och fått färre utmaningar och på så sätt blivit mindre positiva till de naturvetenskapliga ämnena?

Det tredje resultatet, en större andel hög- och lågpresterande pojkar tycker att de tre ämnena är tråkiga 2007 jämfört med 1995, diskuteras utifrån begreppen "antipluggkultur" och att vara "cool". Kan resultatet från denna studie indikera att det är viktigare för pojkar 2007 att ha en attityd att visa sig ”cool” och att inte plugga. Kan detta ha påverkat attityderna till de naturvetenskapliga ämnena negativt?

Slutligen visar resultaten att lågpresterande flickor och pojkar tycker att de presterar bättre 2007 än 1995 och det diskuteras mot bakgrund av förändringarna av arbetsmetoder i den svenska skolan. Mer tid ägnas åt individuellt arbete vilket kan innebära att de lågpresterande eleverna väljer att inte arbeta med svårare uppgifter och att de därför upplever att de presterar bättre.

Avhandlingen avslutas med mina egna reflektioner kring undervisningen i de naturvetenskapliga ämnena i grundskolan, kring förändringarna av flickors och pojkars attityder till naturvetenskap utifrån resultaten från denna studie och kring mina erfarenheter som lärare i dessa ämnen.

• 97.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Umeå universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
Gapet har minskat: skillnader mellan hög- och lågpresterande flickors och pojkars attityder till biologi, fysik och kemi 1995 och 20072011Ingår i: NorDiNa: Nordic Studies in Science Education, ISSN 1504-4556, E-ISSN 1894-1257, Vol. 7, nr 1, s. 3-16Artikel i tidskrift (Refereegranskat)

This article explores the change over time of boys’ and girls’ attitudes towards biology, physics and chemistry. We use data from the TIMSS studies for grade 8 in Sweden to investigate how the attitudes for high- and low performing pupils have changed between 1995 and 2007. The attitude is measured by four questions from the student questionnaire in the TIMSS study. The results indicate that there have been some changes in attitudes between 1995 and 2007. High-achieving pupils and especially boys have a more negative attitude towards all three subjects, biology, physics and chemistry, in 2007 compared to 1995. The low-achieving students think that they are performing better in all three subjects 2007 compared to 1995. The difference between the group that are most positive to physics and chemistry and the least positive group has diminished between the two years. The results are discussed in relation to the changes in Swedish schools during the period.

• 98.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
Expanding operation ranges using active flow control in Francis turbines2014Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)

This report contains an investigation of fluid injection techniques used in the purpose of reducing deleterious flow effects occurring in the draft tube of Francis turbines when operating outside nominal load. There is a focus on implement ability at Jämtkrafts hydroelectric power plants and two power plants were investigated, located in series with each other named Lövhöjden and Ålviken. The only profitable scenario found with some degree of certainty was an increase in the operating range upwards to allow overload operation.

Findings show that both air and water can be introduced in various locations to improve hydraulic efficiency around the turbine parts as well as reduce pressure pulsations in harmful operating regions. Investments in such systems have proven useful and profitable at several facilities with poorly adapted operating conditions. But due to losses in efficiency when operating injection systems, it turns out unprofitable in situations where it does not improve the operating range in a way that is resulting in increased annual or peak production.

• 99.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Arkitekthögskolan vid Umeå universitet.
Rethinking the urban: ecology, infrastructure, urbanization2015Ingår i: ASA15 Symbiotic anthropologies: theoretical commensalities and methodological mutualisms, University of Exeter , 2015, s. 64-64Konferensbidrag (Refereegranskat)

This paper will explore a new notion of urbanity in the context of planetary urbanisation, through the investigation and analysis of the following themes: urban-ecology, urban-infrastructure, and new processes of urbanisation.

• 100. Aeppli, Christoph
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
Investigating formation and degradation of polychlorinated phenols in the environment using chlorine and carbon stable isotope fractionation2011Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 242, s. 214-ENVR-Artikel i tidskrift (Refereegranskat)
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