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Träfflista för sökning "AMNE:(NATURAL SCIENCES Mathematics Computational Mathematics) "

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  • Ögren, Magnus, 1977-, et al. (författare)
  • A numerical damped oscillator approach to constrained Schrödinger equations
  • 2020
  • Ingår i: European journal of physics. - : Institute of Physics (IOP). - 0143-0807 .- 1361-6404. ; 41:6
  • Tidskriftsartikel (refereegranskat)abstract
    • This article explains and illustrates the use of a set of coupled dynamical equations, second order in a fictitious time, which converges to solutions of stationary Schrödinger equations with additional constraints. In fact, the method is general and can solve constrained minimization problems in many fields. We present the method for introductory applications in quantum mechanics including three qualitative different numerical examples: the radial Schrödinger equation for the hydrogen atom; the two-dimensional harmonic oscillator with degenerate excited states; and a non-linear Schrödinger equation for rotating states. The presented method is intuitive, with analogies in classical mechanics for damped oscillators, and easy to implement, either in own coding, or with software for dynamical systems. Hence, we find it suitable to introduce it in a continuation course in quantum mechanics or generally in applied mathematics courses which contain computational parts. The undergraduate student can for example use our derived results and the code (supplemental material) to study the Schrödinger equation in 1D for any potential. The graduate student and the general physicist can work from our three examples to derive their own results for other models including other global constraints.
  • Hamon, Thierry, et al. (författare)
  • Combining Compositionality and Pagerank for the Identification of Semantic Relations between Biomedical Words
  • 2012
  • Ingår i: BioNLP. - 9781937284206 - 1937284204 ; , s. 109-117
  • Konferensbidrag (refereegranskat)abstract
    • The acquisition of semantic resources and relations is an important task for several applications, such as query expansion, information retrieval and extraction, machine translation. However, their validity should also be computed and indicated, especially for automatic systems and applications. We exploit the compositionality based methods for the acquisition of synonymy relations and of indicators of these synonyms. We then apply pagerank-derived algorithm to the obtained semantic graph in order to filter out the acquired synonyms. Evaluation performed with two independent experts indicates that the quality of synonyms is systematically improved by 10 to 15% after their filtering.
  • Lindahl, Karl-Olof, 1975- (författare)
  • Applied Algebraic Dynamics
  • 2010
  • Ingår i: Mathematical modeling: non-Archimedean Dynamics. - : Pleiades Publishing, Ltd.. ; 2:4, s. 360-362
  • Tidskriftsartikel (refereegranskat)
  • Lundow, Per Håkan, et al. (författare)
  • 2008
  • Ingår i: LMS Journal of Computation and Mathematics. - : Cambridge University Press. - 1461-1570 .- 1461-1570. ; 11, s. 1-14
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this paper is to extend the previous work on transfer matrix compression in the case of graph homomorphisms. For H-homomorphisms of lattice-like graphs we demonstrate how the automorphisms of H, as well as those of the underlying lattice, can be used to reduce the size of the relevant transfer matrices. As applications of this method we give currently best known bounds for the number of 4- and 5-colourings of the square grid, and the number of 3- and 4-colourings of the three-dimensional cubic lattice. Finally, we also discuss approximate compression of transfer matrices.
  • Eriksson, Kimmo, et al. (författare)
  • Biases for acquiring information individually rather than socially
  • 2009
  • Ingår i: Journal of Evolutionary Psychology. - 0737-4828. ; 7:4, s. 309-329
  • Tidskriftsartikel (refereegranskat)abstract
    • We discuss theoretical and empirical arguments for a human bias to acquire information individually rather than socially. In particular, we argue that when other people can be observed, information collection is a public good and hence some of the individual variation in the choice between individual and social learning can be explained by variation in social value orientation. We conducted two experimental studies, based on the game Explore & Collect, to test the predictions that (1) socially and individually acquired information of equal objective value are treated differently, and (2) prosocial subjects tend to spend more effort than selfish subjects on individual acquiring of information. Both predictions were supported.
  • Weishaupt, Holger, 1983-, et al. (författare)
  • Graph Centrality Based Prediction of Cancer Genes
  • 2016
  • Ingår i: Engineering Mathematics II. - : Springer. - 9783319421049 - 9783319421056 ; , s. 275-311
  • Bokkapitel (refereegranskat)abstract
    • Current cancer therapies including surgery, radiotherapy and chemotherapy are often plagued by high failure rates. Designing more targeted and personalized treatment strategies requires a detailed understanding of druggable tumor drivergenes. As a consequence, the detection of cancer driver genes has evolved to a critical scientific field integrating both high-through put experimental screens as well as computational and statistical strategies. Among such approaches, network based prediction tools have recently been accentuated and received major focus due to their potential to model various aspects of the role of cancer genes in a biological system. In this chapter, we focus on how graph centralities obtained from biological networks have been used to predict cancer genes. Specifically, we start by discussing the current problems in cancer therapy and the reasoning behind using network based cancer gene prediction, followed by an outline of biological networks, their generation and properties. Finally, we review major concepts, recent results as well as future challenges regarding the use of graph centralities in cancer gene prediction.
  • Dupuch, Marie, et al. (författare)
  • Comparison of Clustering Approaches through Their Application to Pharmacovigilance Terms
  • 2013
  • Ingår i: Artificial Intelligence in Medicine. Lecture Notes in Computer Science, vol. 7885. - Berlin Heidelberg : Springer. - 9783642383250 - 9783642383267 ; , s. 58-67
  • Bokkapitel (refereegranskat)abstract
    • In different applications (i.e., information retrieval, filteringor analysis), it is useful to detect similar terms and to provide the possibilityto use them jointly. Clustering of terms is one of the methods whichcan be exploited for this. In our study, we propose to test three methodsdedicated to the clustering of terms (hierarchical ascendant classification,Radius and maximum), to combine them with the semantic distance algorithmsand to compare them through the results they provide whenapplied to terms from the pharmacovigilance area. The comparison indicatesthat the non disjoint clustering (Radius and maximum) outperformthe disjoint clusters by 10 to up to 20 points in all the experiments.
  • Nettelblad, Carl, 1985- (författare)
  • Two Optimization Problems in Genetics : Multi-dimensional QTL Analysis and Haplotype Inference
  • 2012
  • Ingår i: eSSENCE. - Uppsala : Acta Universitatis Upsaliensis.
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • The existence of new technologies, implemented in efficient platforms and workflows has made massive genotyping available to all fields of biology and medicine. Genetic analyses are no longer dominated by experimental work in laboratories, but rather the interpretation of the resulting data. When billions of data points representing thousands of individuals are available, efficient computational tools are required. The focus of this thesis is on developing models, methods and implementations for such tools.The first theme of the thesis is multi-dimensional scans for quantitative trait loci (QTL) in experimental crosses. By mating individuals from different lines, it is possible to gather data that can be used to pinpoint the genetic variation that influences specific traits to specific genome loci. However, it is natural to expect multiple genes influencing a single trait to interact. The thesis discusses model structure and model selection, giving new insight regarding under what conditions orthogonal models can be devised. The thesis also presents a new optimization method for efficiently and accurately locating QTL, and performing the permuted data searches needed for significance testing. This method has been implemented in a software package that can seamlessly perform the searches on grid computing infrastructures.The other theme in the thesis is the development of adapted optimization schemes for using hidden Markov models in tracing allele inheritance pathways, and specifically inferring haplotypes. The advances presented form the basis for more accurate and non-biased line origin probabilities in experimental crosses, especially multi-generational ones. We show that the new tools are able to reconstruct haplotypes and even genotypes in founder individuals and offspring alike, based on only unordered offspring genotypes. The tools can also handle larger populations than competing methods, resolving inheritance pathways and phase in much larger and more complex populations. Finally, the methods presented are also applicable to datasets where individual relationships are not known, which is frequently the case in human genetics studies. One immediate application for this would be improved accuracy for imputation of SNP markers within genome-wide association studies (GWAS).
  • Nilsson, Galina, 1960-, et al. (författare)
  • Do We Deliver Effective Maths Support for Students?
  • 2012
  • Ingår i: The European Conference on Educational Research 2012.
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • European countries are facing a crisis in preparing qualified staff for working in science and engineering. Declining numbers of students pursuing careers in these areas and poor quality of maths education in secondary schools are the principal factors contributing to this problem.Students entering universities have a diverse level of maths knowledge which is often below university requirements. University teachers often face a challenging and complex task of teaching such a diverse student body. One of the most common ways to tackle this problem and to raise the level of students' maths knowledge to the required standard is to introduce a maths foundation course before to mainstream teaching begins. However, this is not always possible because of academic staff availability and/or time and cost constraints. Another solution is to provide additional help with maths-related problems by running drop-in sessions, workshops and/or tutorials.This study analyses the efficiency of maths support provision in two universities: Leeds Metropolitan University, UK and University West, Sweden and is part of an ongoing research collaboration between the two universities. The present work reflects the first stage of this research and is focused on evaluating the efficiency of the maths support in these two institutions from the perspectives of academic staff. The next stage of our research will include the analysis of this provision from the students' perspectives.The literature on this topic is growing but limited and is mainly focussed either on quantitative indicators: the numbers of maths support centres and staff employed, hours when this support is available, numbers of students attending etc. [e.g.1, 2] or at the correlation between maths support session attendance and students' test or exam results [3].However, there has been little research about how the tutors who deliver this maths support evaluate the effectiveness of their work and what they think can be done to provide maths support which can successfully meet students' needs.In both universities the main part of maths support provision consists of drop-in workshops which are available throughout the week. Leeds Metropolitan University does not offer very maths intensive courses, however, maths elements are incorporated into a number of subject areas such as  nursing, business, sports science psychology, education etc. There are specific workshops for maths and statistics. Two dedicated members of staff from the maths support centre run these one hour sessions. University West offers both maths intensive courses such as engineering and computer science, and less maths intensive courses such as education and nursing. Its maths workshops are open to all students and cover all subject areas. Selected academic staff from the Maths department are appointed to run three-to-four hour sessions three times a week as part of their teaching load.One tutor from Leeds Metropolitan University and three tutors from University West participated in the study.MethodOur study is conducted in two stages and uses mixed methods for data collection: questionnaires for students, interviews with tutors and observations during the sessions. The combination of these methods will give us a fuller picture of the effectiveness of maths support in these two universities. At this stage of our research we collected information about which students used the sessions – their departments, year and course of study, why they attended and what problems they needed help with – which we then analysed. We also observed how tutors were coping with a wide range of maths topics and teaching methods. We conducted interviews with the tutors to understand in more detail how they work, the difficulties they face, the types of problems that arise and the ways students expect help to be provided as well as tutors' ideas about more effective ways of providing maths support. At the next stage of our research we will be analysing the feedback from students and their suggestions on how maths support provision can be improved. The two-stage approach will provide us with a better understanding of the students' real needs and will facilitate the deployment of more effective student support.Expected OutcomesThe academic staff from both universities noticed a broad variation in students' maths abilities. The majority of workshop attendees were first year students struggling with their assignments as well as undergraduates who failed their exams and wanted help as part of their resit preparation. High performing students sometimes came to perfect their knowledge. In Leeds, postgraduate students often attended the workshops, particularly on statistical data analysis. The students came from a wide range of subject areas and tutors found that sometimes it took extra time to answer the students' subject-specific questions. The number of attendees increased before exams or project submission deadlines. Based on the interviews and observations we concluded that students are often not fully engaged during the workshops, instead preferring a 'solve this for me' approach. However, implementing student-centred methods which increase students' engagement with the learning process (e.g. problem-based learning and peer-assisted learning [4-6]) can help.  Subject-specific workshops (e.g. for nurses, business students or teachers) help to focus on students' particular needs, and individual tutorials can accommodate other needs. The paper concludes with recommendations for improving the effectiveness of maths support for students and discusses the next stage of the research.References1. Perkin G. and Croft T. (2004), "Mathematics Support Centres – the extent of current provision", MSOR Connections, May 2004, Vol. 6 No 2 p 14-18. 2. Lawson, D.A. and Reed J. (2002), "University mathematics support centres: help for struggling students". In Ivanchev, D. and Todorov, M.D (eds.), Applications of Mathematics in Engineering and Economics. Heron Press, Sofia, pp.686-692 3. Pell G. and Croft T., (2008), "Mathematics Support – Support for all?" Teaching Mathematics and its Applications, 27 (4), pp. 167-173. 4. Anari M., (2006) An analysis of a maths workshop – students with mathematical difficulties. (in Swedish). Thesis. Mälardalen University, the Library of the Institute for Mathematics and  Physics. 5. Nilsson G. and Luchinskaya E. (2007), "Problem-based Learning and competence development: a Case Study of Teaching Mathematics to Computer Science Students", Journal of Research in Teacher Education, 2007, No 3. p 13-21. 6. Nilsson G. and Luchinskaya E. (2009), " Using Problem-based and Peer-assisted Learning in Teaching Mathematics to University Students: Focus on Competence Development." Paper presented at the European Educational Research Conference, ECER 2009, Vienna, Austria, September 2009.
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