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Publications (4 of 4) Show all publications
Björnham, O., Brännström, N. & Persson, L. A. (2022). Absolutely continuous copulas with prescribed support constructed by differential equations, with an application in toxicology. Communications in Statistics - Theory and Methods, 51(19), 6601-6625
Open this publication in new window or tab >>Absolutely continuous copulas with prescribed support constructed by differential equations, with an application in toxicology
2022 (English)In: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415X, Vol. 51, no 19, p. 6601-6625Article in journal (Refereed) Published
Abstract [en]

A new method for constructing absolutely continuous two-dimensional copulas by differential equations is presented. The copulas are symmetric with respect to reflection in the opposite diagonal. The support of the copula density may be prescribed to arbitrary opposite symmetric hypographs of invertible functions, containing the diagonal. The method is applied to toxicological probit modeling, where new compatibility conditions for the probit parameters are derived.

Place, publisher, year, edition, pages
Taylor & Francis, 2022
Keywords
Absolutely continuous copula, symmetry, differential equation, probit model
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:umu:diva-179046 (URN)10.1080/03610926.2020.1864825 (DOI)000603892800001 ()2-s2.0-85098506044 (Scopus ID)
Available from: 2021-01-29 Created: 2021-01-29 Last updated: 2023-03-23Bibliographically approved
Persson, L., Boso, J., Nylén, T. & Ramebäck, H. (2018). Application of a Monte Carlo method to the uncertainty assessment in in situ gamma-ray spectrometry. Journal of Environmental Radioactivity, 187, 1-7
Open this publication in new window or tab >>Application of a Monte Carlo method to the uncertainty assessment in in situ gamma-ray spectrometry
2018 (English)In: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 187, p. 1-7Article in journal (Refereed) Published
Abstract [en]

In situ gamma-ray spectrometry has since the introduction of portable germanium detectors been a widely used method for the assessment of radionuclide ground deposition activity levels. It is, however, a method that is most often associated with fairly large and, more important, poorly known combined measurement uncertainties. In this work an uncertainty analysis of in situ gamma ray spectrometry in accordance with the Guide to the Expression of Uncertainty in Measurements is presented. The uncertainty analysis takes into account uncertainty contributions from the calibration of the detector system, the assumed activity distribution in soil, soil density, detector height and air density. As a result, measurement results from in situ gamma spectrometry will serve as a better basis for decision-making in e.g. radiological emergencies.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
HPGe, In situ gamma ray spectrometry, Radioactive fallout, Monte Carlo method, Uncertainty
National Category
Environmental Sciences related to Agriculture and Land-use Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:umu:diva-148623 (URN)10.1016/j.jenvrad.2018.02.003 (DOI)000428833900001 ()29459254 (PubMedID)2-s2.0-85042092203 (Scopus ID)
Available from: 2018-06-26 Created: 2018-06-26 Last updated: 2023-03-24Bibliographically approved
Brännström, N. & Persson, L. A. (2015). A measure theoretic approach to linear inverse atmospheric dispersion problems. Inverse Problems, 31(2), Article ID 025009.
Open this publication in new window or tab >>A measure theoretic approach to linear inverse atmospheric dispersion problems
2015 (English)In: Inverse Problems, ISSN 0266-5611, E-ISSN 1361-6420, Vol. 31, no 2, article id 025009Article in journal (Refereed) Published
Abstract [en]

Using measure theoretic arguments, we provide a general framework for describing and studying the general linear inverse dispersion problem where no a priori assumptions on the source function has been made (other than assuming that it is indeed a source, i.e. not a sink). We investigate the source-sensor relationship and rigorously state solvability conditions for when the inverse problem can be solved using a least-squares optimization method. That is, we derive conditions for when the least-squares problem is well-defined.

Keywords
atmospheric dispersion, inverse problem, measure theory
National Category
Mathematical Analysis
Identifiers
urn:nbn:se:umu:diva-100774 (URN)10.1088/0266-5611/31/2/025009 (DOI)000349300400009 ()2-s2.0-84922134871 (Scopus ID)
Available from: 2015-04-01 Created: 2015-03-09 Last updated: 2023-03-23Bibliographically approved
Åhag, P., Czyz, R. & Persson, L. (2012). Radially symmetric plurisubharmonic functions. Annales Polonici Mathematici, 106, 1-17
Open this publication in new window or tab >>Radially symmetric plurisubharmonic functions
2012 (English)In: Annales Polonici Mathematici, ISSN 0066-2216, E-ISSN 1730-6272, Vol. 106, p. 1-17Article in journal (Refereed) Published
Abstract [en]

In this note we consider radially symmetric plurisubharmonic functions and the complex Monge–Ampère operator. We prove among other things a complete characterization of unitary invariant measures for which there exists a solution of the complex Monge–Ampère equation in the set of radially symmetric plurisubharmonic functions. Furthermore, we prove in contrast to the general case that the complex Monge–Ampère operator is continuous on the set of radially symmetric plurisubharmonic functions. Finally we characterize radially symmetric plurisubharmonic functions among the subharmonic ones using merely the laplacian.

National Category
Mathematical Analysis
Identifiers
urn:nbn:se:umu:diva-50907 (URN)10.4064/ap106-0-1 (DOI)000311525700001 ()2-s2.0-84873465878 (Scopus ID)
Available from: 2012-01-01 Created: 2012-01-01 Last updated: 2023-03-23Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0504-6844

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