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Wijayatunga, Priyantha
Publications (10 of 23) Show all publications
Suhr, O. B., Wixner, J., Anan, I., Lundgren, H.-E., Wijayatunga, P., Westermark, P. & Ihse, E. (2019). Amyloid fibril composition within hereditary Val30Met (p. Val50Met) transthyretin amyloidosis families. PLoS ONE, 14(2), Article ID e0211983.
Open this publication in new window or tab >>Amyloid fibril composition within hereditary Val30Met (p. Val50Met) transthyretin amyloidosis families
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2019 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, no 2, article id e0211983Article in journal (Refereed) Published
Abstract [en]

Background: The amyloid fibril in hereditary transthyretin (TTR) Val30Met (pVal50Met) amyloid (ATTR Val30Met) amyloidosis is composed of either a mixture of full-length and TTR fragments (Type A) or of only full-length TTR (Type B). The type of amyloid fibril exerts an impact on the phenotype of the disease, and on the outcome of diagnostic procedures and therapy. The aim of the present study was to investigate if the type of amyloid fibril remains the same within ATTR Val30Met amyloidosis families. Methods: Fifteen families were identified in whom at least two first-degree relatives had their amyloid fibril composition determined. The type of ATTR was determined by Western blot in all but two patients. For these two patients a positive 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy indicated ATTR Type A. Results: In 14 of the 15 families, the same amyloid fibril composition was noted irrespective of differences in age at onset. In the one family, different ATTR fibril types was found in two brothers with similar ages at onset. Conclusions: Family predisposition appears to have an impact on amyloid fibril composition in members of the family irrespective of their age at onset of disease, but if genetically determined, the gene/genes are likely to be situated at another location than the TTR gene in the genome.

Place, publisher, year, edition, pages
Public Library Science, 2019
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:umu:diva-157583 (URN)10.1371/journal.pone.0211983 (DOI)000459806400043 ()30811423 (PubMedID)
Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-04-01Bibliographically approved
Wijayatunga, P. & Sundström, N. (2019). Discriminative Prediction of Adverse Events for Optimized Therapies Following Traumatic Brain Injury. In: : . Paper presented at 31st Swedish AI Society Workshop 2019, June 18–19, 2019, Umeå, Sweden. Umeå, Article ID 3.
Open this publication in new window or tab >>Discriminative Prediction of Adverse Events for Optimized Therapies Following Traumatic Brain Injury
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Traumatic brain injury (TBI) causes temporary or perma- nent alteration in brain functions. At intensive care units, TBI patients are usually multimodally monitored, thus rendering large volumes of data on many physiological variables. For the physician, these data are difficult to interpret due to their complexity, speed and volume. Thus, computa- tional aids are recommended, e.g., for predicting patient’s clinical status in near future. In this article, we describe a probabilistic model that can be used for aiding physician’s decision making process in TBI patient care in real time. Our model tries to capture time varying patterns of patient’s clinical information. The model is built by using a discrimi- native model learning framework so that it can predict adverse clinical events with a higher level of accuracy. That is, our model is built so that prediction of certain desired events are given more attention than that of the other less important ones. This can be achieved by estimating model parameters in such a way, for e.g. using a cost function, when a suitable model structure has been selected, that again can be done dis- criminatively. However, such estimation procedures have no closed form solutions, so numerical optimization methods are used.

Place, publisher, year, edition, pages
Umeå: , 2019
Keywords
Dependence, Accuracy, Clinical, Real time
National Category
Probability Theory and Statistics
Research subject
Statistics
Identifiers
urn:nbn:se:umu:diva-160522 (URN)
Conference
31st Swedish AI Society Workshop 2019, June 18–19, 2019, Umeå, Sweden
Available from: 2019-06-19 Created: 2019-06-19 Last updated: 2019-06-20Bibliographically approved
Wijayatunga, P., Diggle, P. J., Baillie, M., Vandemeulebroecke, M., Jones, W. R., Fassò, A., . . . Bowman, A. W. (2019). Discussion on the meeting on 'Data visualization' [Letter to the editor]. Journal of the Royal Statistical Society: Series A (Statistics in Society), 182(2), 433-441
Open this publication in new window or tab >>Discussion on the meeting on 'Data visualization'
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2019 (English)In: Journal of the Royal Statistical Society: Series A (Statistics in Society), ISSN 0964-1998, E-ISSN 1467-985X, Vol. 182, no 2, p. 433-441Article in journal, Letter (Other academic) Published
Abstract [en]

Visualizing both conditional and marginal associations in contingency tables by using simple diagrams is discussed

Place, publisher, year, edition, pages
UK: Royal Statistical Society, 2019
Keywords
Marginal and conditional associations
National Category
Probability Theory and Statistics
Research subject
Statistics
Identifiers
urn:nbn:se:umu:diva-155442 (URN)10.1111/rssa.12435 (DOI)
Available from: 2019-01-16 Created: 2019-01-16 Last updated: 2019-01-25Bibliographically approved
Babb, P., Zhang, L.-C., Allin, P., Wallgren, A., Wallgren, B., Blunt, G., . . . Wijayatunga, P. (2018). Statistical challenges of administrative and transaction data: Discussion on the paper by Hand. Journal of the Royal Statistical Society: Series A (Statistics in Society), 181(3), 578-605
Open this publication in new window or tab >>Statistical challenges of administrative and transaction data: Discussion on the paper by Hand
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2018 (English)In: Journal of the Royal Statistical Society: Series A (Statistics in Society), ISSN 0964-1998, E-ISSN 1467-985X, Vol. 181, no 3, p. 578-605Article in journal, Editorial material (Other academic) Published
Place, publisher, year, edition, pages
Wiley-Blackwell, 2018
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:umu:diva-150388 (URN)000434143700002 ()
Note

This is a discussion on the paper "Statistical challenges of administrative and transaction data" by David J. Hand. The full paper and the discussion can be found at https://doi.org/10.1111/rssa.12315.

Available from: 2018-08-06 Created: 2018-08-06 Last updated: 2018-08-09Bibliographically approved
Dawid, P., Wijayatunga, P. & Pierides, D. C. (2017). Beyond subjective and objective in statistics: Discussion on the paper by Gelman and Hennig. Journal of the Royal Statistical Society: Series A (Statistics in Society), 180(4), 997-1033
Open this publication in new window or tab >>Beyond subjective and objective in statistics: Discussion on the paper by Gelman and Hennig
2017 (English)In: Journal of the Royal Statistical Society: Series A (Statistics in Society), ISSN 0964-1998, E-ISSN 1467-985X, Vol. 180, no 4, p. 997-1033Article in journal, Editorial material (Other academic) Published
Abstract [en]

Subjectivity and objectivity in statistical modelling is discussed.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2017
Keywords
regression, effect, causal
National Category
Probability Theory and Statistics
Research subject
Statistics
Identifiers
urn:nbn:se:umu:diva-141560 (URN)
Note

This is a discussion on the paper "Beyond subjective and objective in statistics" by Gelman and Henning. The full paper and the discussion can be found at https://doi.org/10.1111/rssa.12276. 

Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2018-08-09Bibliographically approved
Wijayatunga, P. (2017). Discussion on the paper by Caron and Fox [Letter to the editor]. Journal of The Royal Statistical Society Series B-statistical Methodology, 79(5), 1359-1359
Open this publication in new window or tab >>Discussion on the paper by Caron and Fox
2017 (English)In: Journal of The Royal Statistical Society Series B-statistical Methodology, ISSN 1369-7412, E-ISSN 1467-9868, Vol. 79, no 5, p. 1359-1359Article in journal, Letter (Other academic) Published
Abstract [en]

A measure of dependence for graph models

Place, publisher, year, edition, pages
USA: John Wiley & Sons, 2017
Keywords
Measures of dependence
National Category
Probability Theory and Statistics
Research subject
Statistics
Identifiers
urn:nbn:se:umu:diva-141349 (URN)
Note

Referring to: Francois Caron, Emily B. Fox: Sparse graphs using exchangeable random measures. Journal of The Royal Statistical Society Series B-statistical Methodology. 2017;79;Part 5. DOI: 10.1111/rssb.12233

Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2019-03-06Bibliographically approved
Wijayatunga, P. (2017). Resolving the Lord's Paradox. In: Marco Grzegorczyk and Giacomo Ceoldo (Ed.), Proceedings of the 32nd International Workshop on Statistical Modelling: Volume II. Paper presented at 32nd International Workshop on Statistical Modelling (IWSM 2017), Groningen, Netherlands, 3-7 July, 2017 (pp. 223-226). Groningen, Netherlands: International Workshop on Statistical Modelling (IWSM), II
Open this publication in new window or tab >>Resolving the Lord's Paradox
2017 (English)In: Proceedings of the 32nd International Workshop on Statistical Modelling: Volume II / [ed] Marco Grzegorczyk and Giacomo Ceoldo, Groningen, Netherlands: International Workshop on Statistical Modelling (IWSM) , 2017, Vol. II, p. 223-226Conference paper, Published paper (Refereed)
Abstract [en]

An explanation to Lord’s paradox using ordinary least square regres- sion models is given. It is not a paradox at all, if the regression parameters are interpreted as predictive or as causal with stricter conditions and be aware of laws of averages. We use derivation of a super-model from a given sub-model, when its residuals can be modelled with other potential predictors as a solution. 

Place, publisher, year, edition, pages
Groningen, Netherlands: International Workshop on Statistical Modelling (IWSM), 2017
Keywords
Effect, Predictive, Causal, Confounding
National Category
Natural Sciences Probability Theory and Statistics
Research subject
Statistics
Identifiers
urn:nbn:se:umu:diva-137583 (URN)
Conference
32nd International Workshop on Statistical Modelling (IWSM 2017), Groningen, Netherlands, 3-7 July, 2017
Available from: 2017-07-06 Created: 2017-07-06 Last updated: 2018-06-09Bibliographically approved
Wijayatunga, P. (2016). A geometric view on Pearson's correlation coefficient and a generalization of it to non-linear dependencies. Ratio Mathematica, 30, 3-21, Article ID 1.
Open this publication in new window or tab >>A geometric view on Pearson's correlation coefficient and a generalization of it to non-linear dependencies
2016 (English)In: Ratio Mathematica, ISSN 1592-7415, Vol. 30, p. 3-21, article id 1Article in journal (Refereed) Published
Abstract [en]

Measuring strength or degree of statistical dependence between two random variables is a common problem in many domains. Pearson's correlation coefficient $\rho$ is an accurate measure of linear dependence. We show that $\rho$ is a normalized, Euclidean type distance between joint probability distribution of the two random variables and that when their independence is assumed while keeping their marginal distributions. And the normalizing constant is the geometric mean of two maximal  distances; each between the joint probability distribution when the full linear dependence is assumed while preserving respective marginal distribution and that when the independence is assumed. Usage of it  is  restricted to linear dependence because it is based on  Euclidean type distances that are generally not metrics and considered full dependence is linear. Therefore, we argue that if a suitable distance metric is used while considering all possible maximal dependences then it can measure any non-linear dependence.  But then, one must define all the full dependences.  Hellinger distance that is a metric can be used as the distance measure between probability distributions and obtain a generalization of $\rho$ for the discrete case.

Place, publisher, year, edition, pages
Italy: eiris, 2016
Keywords
metric/distance, probability simplex, normalization
National Category
Probability Theory and Statistics
Research subject
Statistics
Identifiers
urn:nbn:se:umu:diva-128231 (URN)
Available from: 2016-11-29 Created: 2016-11-29 Last updated: 2018-06-09Bibliographically approved
Wijayatunga, P. (2016). Data Deluge and Its Analysis Issues. In: Proceedings of the 2nd International Conference in Accounting Researchers and Educators (ICARE 2016): . Paper presented at 2nd International Conference in Accounting Researchers and Educators (ICARE 2016), Sri Lanka, 11th January 2016. (pp. 21-21). Kelaniya: Department of Accountancy, University of Kelaniya, Article ID 21.
Open this publication in new window or tab >>Data Deluge and Its Analysis Issues
2016 (English)In: Proceedings of the 2nd International Conference in Accounting Researchers and Educators (ICARE 2016), Kelaniya: Department of Accountancy, University of Kelaniya , 2016, p. 21-21, article id 21Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Current availability of enormous amount of data is mainly due to technological advances. They are useful drawing inferences for creating new businesses, formulation of new policies or revising existing ones, etc. However, much of analyses are performed either by subject domain experts implementing mathematical and computational models incorrectly or by mathematical and computational professionals, purely on data driven basis without paying required attention to the subject domain knowledge. Both of these exercises often result in incorrect inferences and therefore they may harm the society, especially when their inferences are used in practice. We argue that, in order to get valid inferences these two parties should work together. Here we briefly discuss some of the issues that the large-scale data analyses should take into account, especially in open data and big data. We also briefly discuss our solutions that are rather simple to implement.

Place, publisher, year, edition, pages
Kelaniya: Department of Accountancy, University of Kelaniya, 2016
Series
ICARE, ISSN 2465- 6046
Keywords
Open data, Big data, Statistical, Causal, Inference
National Category
Probability Theory and Statistics
Research subject
Statistics
Identifiers
urn:nbn:se:umu:diva-132588 (URN)
Conference
2nd International Conference in Accounting Researchers and Educators (ICARE 2016), Sri Lanka, 11th January 2016.
Available from: 2017-03-17 Created: 2017-03-17 Last updated: 2019-02-07Bibliographically approved
Brink, M., Hansson, M., Mathsson-Alm, L., Wijayatunga, P., Verheul, M., Trouw, L., . . . Rantapää-Dahlqvist, S. (2016). Rheumatoid Factor Isotypes in Relation to Antibodies Against Citrullinated Peptides and Anti-Carbamylated Antibodies in Individuals Before the Onset of Rheumatoid Arthritis. Arthritis Research & Therapy, 18, Article ID 43.
Open this publication in new window or tab >>Rheumatoid Factor Isotypes in Relation to Antibodies Against Citrullinated Peptides and Anti-Carbamylated Antibodies in Individuals Before the Onset of Rheumatoid Arthritis
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2016 (English)In: Arthritis Research & Therapy, ISSN 1478-6354, E-ISSN 1478-6362, Vol. 18, article id 43Article in journal (Refereed) Published
Abstract [en]

Background: The presence of rheumatoid factor (RF), anti-carbamylated protein antibodies (anti-CarP) and antibodies against citrullinated protein and peptides (ACPA) precedes the onset of symptoms of rheumatoid arthritis (RA) by several years. Relationships between the development of these antibodies are not obvious. 

Methods: Three isotypes [immunoglobulin A (IgA), IgG and IgM) of RF were analysed in 321 pre-symptomatic individuals who provided 598 samples collected a median of 6.2 (interquartile range 7.2) years before the onset of symptoms, and in 492 population control subjects. All samples were donated to the Biobank of Northern Sweden. RF isotypes were analysed using the EliA system (Phadia GmbH, Freiburg, Germany) with 96 % specificity according to receiver operating characteristic curves. Ten ACPA specificities were analysed using the ImmunoCAP ISAC system, and anti-CCP2 and anti-CarP antibodies were evaluated using enzyme-linked immunosorbent assays. 

Results: The frequencies of RF isotypes in pre-symptomatic individuals were significantly increased compared with control subjects (p < 0.0001). In samples collected >= 15 years before the onset of symptoms, the IgA-RF isotype was significantly more prevalent than the most frequent ACPAs. Combinations of IgM- and IgA-RF isotypes with ACPA specificities [a-enolase (CEP-1/Eno(5-21))], fibrinogen (Fib)beta(36-52), Fiba(580-600), filaggrin (CCP-1/Fil(307-324)) and anti-CCP2 antibodies were associated with a significantly shorter time to onset of symptoms (p < 0.001-0.05). Using conditional inference tree analysis, anti-CCP2 in combination with anti-filaggrin antibodies gave the highest probability, 97.5 %, for disease development. 

Conclusions: RF isotypes predicted the development of RA, particularly in combination with ACPA, anti-CCP2 or anti-CarP antibodies. The highest probability for disease development was the presence of anti-CCP2 and anti-filaggrin antibodies.

Keywords
Rheumatoid arthritis, Rheumatoid factor, Anti-citrullinated peptide antibodies, Pre-symptomatic individuals, Anti-carbamylated protein antibodies, Anti-CCP2 antibodies
National Category
Rheumatology and Autoimmunity
Identifiers
urn:nbn:se:umu:diva-102852 (URN)10.1186/s13075-016-0940-2 (DOI)000370007700002 ()26860413 (PubMedID)
Note

Originally included in thesis in manuscript form, with the title "Rheumatoid Factor Isotypes in Relation to Antibodies Against Citrullinated Peptides and Anti-Carbamylated Antibodies in Individuals Before the Onset of Rheumatoid Arthritis"

Available from: 2015-05-07 Created: 2015-05-07 Last updated: 2018-06-07Bibliographically approved
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