umu.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Nilsson, Leif
Alternative names
Publications (10 of 26) Show all publications
Pya Arnqvist, N., Ngendangenzwa, B., Lindahl, E. & Nilsson, L. (2019). A statistical learning approach for defect detection and classification on specular carbody surfaces. In: : . Paper presented at Winter Conference in Statistics 2019 - Machine Learning, March 10-14, 2019, Hemavan, Sweden.
Open this publication in new window or tab >>A statistical learning approach for defect detection and classification on specular carbody surfaces
2019 (English)Conference paper, Oral presentation only (Refereed)
National Category
Probability Theory and Statistics Signal Processing
Research subject
Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-158013 (URN)
Conference
Winter Conference in Statistics 2019 - Machine Learning, March 10-14, 2019, Hemavan, Sweden
Projects
FIQA
Funder
Vinnova, 2015-03706
Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-05-10Bibliographically approved
Pya Arnqvist, N., Ngendangenzwa, B., Nilsson, L., Lindahl, E. & Yu, J. (2019). Defect detection and classfiication: statistical learning approach - Part II.
Open this publication in new window or tab >>Defect detection and classfiication: statistical learning approach - Part II
Show others...
2019 (English)Report (Other academic)
Publisher
p. 56
Keywords
Statistical learning, probabilistic classification, defect detection, automated quality inspection
National Category
Probability Theory and Statistics Signal Processing Manufacturing, Surface and Joining Technology
Research subject
Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-161255 (URN)
Funder
Vinnova, 2015-03706
Available from: 2019-07-01 Created: 2019-07-01 Last updated: 2019-07-19Bibliographically approved
Pya Arnqvist, N., Ngendangenzwa, B., Nilsson, L., Lindahl, E. & Yu, J. (2019). Efficient surface finish defect detection using reduced rank spline smoothers. In: CRoNoS & MDA 2019: . Paper presented at CRoNoS & MDA2019, Cyprus, April 14-16, 2019.
Open this publication in new window or tab >>Efficient surface finish defect detection using reduced rank spline smoothers
Show others...
2019 (English)In: CRoNoS & MDA 2019, 2019Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

One of the primary concerns of product quality control in the automotive industry is an automated detection of defects of small sizes on specular car body surfaces. A new statistical learning approach is presented for surface finish defect detection based on spline smoothing method for feature extraction and k-nearest neighbor probabilistic classifier. Rather than analyzing the natural images of the car body surfaces, the deflectometry technique is applied for image acquisition. Reduced rank cubic regression splines are used to smooth the pixel values while the effective degrees of freedom of the obtained smooths serve as components of the feature vector. A key advantage of the approach is that it allows us to reach near zero misclassification error when applying standard learning classifiers. We also propose the probability based performance evaluation metrics as alternatives to the conventional metrics. The usage of those provides the means for uncertainty estimation of the predictive performance of a classifier. Experimental classification results on the images obtained from the pilot system located at Volvo cab plant in Umea, Sweden, show that the proposed approach is much more efficient than compared methods.

National Category
Probability Theory and Statistics Signal Processing
Research subject
Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-158014 (URN)
Conference
CRoNoS & MDA2019, Cyprus, April 14-16, 2019
Projects
FIQA
Funder
Vinnova, 2015-03706
Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-04-16Bibliographically approved
Pya Arnqvist, N., Ngendangenzwa, B., Nilsson, L., Lindahl, E. & Yu, J. (2018). Automated surface finish defect detection using statistical learning approach. In: : . Paper presented at SweDS2018, Umeå University, Sweden, November 20-21, 2018.
Open this publication in new window or tab >>Automated surface finish defect detection using statistical learning approach
Show others...
2018 (English)Conference paper, Oral presentation only (Other academic)
Keywords
Statistical learning, classification, defect detection, automated quality inspection
National Category
Probability Theory and Statistics Manufacturing, Surface and Joining Technology Signal Processing
Research subject
Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-154566 (URN)
Conference
SweDS2018, Umeå University, Sweden, November 20-21, 2018
Projects
FIQA
Funder
Vinnova, 2015-03706
Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2020-03-03Bibliographically approved
Pya Arnqvist, N., Ngendangenzwa, B., Nilsson, L., Lindahl, E. & Yu, J. (2018). Defect detection and classification: statistical learning approach.
Open this publication in new window or tab >>Defect detection and classification: statistical learning approach
Show others...
2018 (English)Report (Other academic)
Publisher
p. 44
Keywords
Statistical learning, classification, defect detection, automated quality inspection
National Category
Probability Theory and Statistics Signal Processing Manufacturing, Surface and Joining Technology
Research subject
Mathematical Statistics
Identifiers
urn:nbn:se:umu:diva-154632 (URN)
Projects
FIQA
Funder
Vinnova, 2015-03706
Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2019-07-19Bibliographically approved
Sonntag-Öström, E., Nordin, M., Dolling, A., Lundell, Y., Nilsson, L. & Slunga Järvholm, L. (2015). Can rehabilitation in boreal forests help recovery from exhaustion disorder?: the randomised clinical trial ForRest. Scandinavian Journal of Forest Research, 30(8), 732-748
Open this publication in new window or tab >>Can rehabilitation in boreal forests help recovery from exhaustion disorder?: the randomised clinical trial ForRest
Show others...
2015 (English)In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 30, no 8, p. 732-748Article in journal (Refereed) Published
Abstract [en]

Modern society is faced with increasing incidence of mental and behavioural disorders. The objective of this study was to evaluate whether visits to boreal forests can be utilised for rehabilitation from exhaustion disorder (ED). This randomised controlled trial comprised of a forest rehabilitation group (n = 35) and a waiting list group (control group) (n = 43) with subsequent cognitive behavioural rehabilitation (CBR) for all participants in both groups. The recovery from ED was compared between the forest rehabilitation and the control group at baseline, after the forest rehabilitation (3 months), and at the end of the CBR (1 year). Both groups had enhanced recovery from ED after the 3-month intervention period and at the end of the CBR (1 year), and there were no significant differences between the groups in terms of psychological health measures. Mental state, attention capacity and preferences for different forest environments were studied during the forest visits. Mental state was improved, but it showed some seasonal differences. A significant effect on attention capacity was found for single forest visits, but there was no effect found for the rehabilitation period as a whole. The most popular forest environments contained easily accessible, open and bright settings with visible water and/or shelter. Forest rehabilitation did not enhance the recovery from ED compared to the control group, but the participants’ well-being was improved after single forest visits.

Place, publisher, year, edition, pages
Taylor & Francis, 2015
Keywords
burnout, human health, mental disorder, nature assisted-therapy, rehabilitation, restoration, urban forestry
National Category
Occupational Health and Environmental Health
Research subject
Public health
Identifiers
urn:nbn:se:umu:diva-92558 (URN)10.1080/02827581.2015.1046482 (DOI)000361601800011 ()
Available from: 2014-08-28 Created: 2014-08-28 Last updated: 2018-06-07Bibliographically approved
Brorsson, C., Dahlqvist, P., Nilsson, L., Thunberg, J., Sylvan, A. & Naredi, S. (2014). Adrenal response after trauma is affected by time after trauma and sedative/analgesic drugs. Injury, 45(8), 1149-1155
Open this publication in new window or tab >>Adrenal response after trauma is affected by time after trauma and sedative/analgesic drugs
Show others...
2014 (English)In: Injury, ISSN 0020-1383, E-ISSN 1879-0267, Vol. 45, no 8, p. 1149-1155Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: The adrenal response in critically ill patients, including trauma victims, has been debated over the last decade. The aim of this study was to assess the early adrenal response after trauma. METHODS: Prospective, observational study of 50 trauma patients admitted to a level-1-trauma centre. Serum and saliva cortisol were followed from the accident site up to five days after trauma. Corticosteroid binding globulin (CBG), dehydroepiandrosterone (DHEA) and sulphated dehydroepiandrosterone (DHEAS) were obtained twice during the first five days after trauma. The effect of time and associations between cortisol levels and; severity of trauma, infusion of sedative/analgesic drugs, cardiovascular dysfunction and other adrenocorticotropic hormone (ACTH) dependent hormones (DHEA/DHEAS) were studied. RESULTS: There was a significant decrease over time in serum cortisol both during the initial 24 h, and from the 2nd to the 5th morning after trauma. A significant decrease over time was also observed in calculated free cortisol, DHEA, and DHEAS. No significant association was found between an injury severity score >/= 16 (severe injury) and a low (< 200 nmol/L) serum cortisol at any time during the study period. The odds for a serum cortisol < 200 nmol/L was eight times higher in patients with continuous infusion of sedative/analgesic drugs compared to patients with no continuous infusion of sedative/analgesic drugs. CONCLUSION: Total serum cortisol, calculated free cortisol, DHEA and DHEAS decreased significantly over time after trauma. Continuous infusion of sedative/analgesic drugs was independently associated with serum cortisol < 200 nmol/L.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Multiple trauma, Adrenal insufficiency, Sedatives
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:umu:diva-91640 (URN)10.1016/j.injury.2014.02.001 (DOI)000340279500004 ()24975481 (PubMedID)1879-0267 (Electronic) 0020-1383 (Linking) (ISBN)
Available from: 2014-08-13 Created: 2014-08-13 Last updated: 2018-06-07Bibliographically approved
Sommar, J. N., Hedmer, M., Lundh, T., Nilsson, L., Skerfving, S. & Bergdahl, I. A. (2014). Investigation of lead concentrations in whole blood, plasma and urine as biomarkers for biological monitoring of lead exposure. Journal of Exposure Science and Environmental Epidemiology, 24(1), 51-57
Open this publication in new window or tab >>Investigation of lead concentrations in whole blood, plasma and urine as biomarkers for biological monitoring of lead exposure
Show others...
2014 (English)In: Journal of Exposure Science and Environmental Epidemiology, ISSN 1559-0631, E-ISSN 1559-064X, Vol. 24, no 1, p. 51-57Article in journal (Refereed) Published
Abstract [en]

Lead in blood is a major concept in biomonitoring of exposure but investigations of its alternatives are scarce. The aim of the study was to describe different lead biomarkers' variances, day-to-day and between individuals, estimating their fraction of the total variance. Repeated sampling of whole blood, plasma and urine were conducted for 48 lead-exposed men and 20 individuals under normal environmental lead exposure, in total 603 measurements. For lead workers, the fraction of the total variance attributed to differences between individuals was 91% for whole-blood lead (geometric mean 227 μg/l; geometric standard deviation (GSD): 1.55 μg/l); plasma 78% (0.57 μg/l; GSD: 1.84 μg/l); density-adjusted urine 82%; and unadjusted urine 75% (23.7 μg/l; GSD: 2.48 μg/l). For the individuals under normal lead exposure, the corresponding fractions were 95% of the total variance for whole blood (20.7 μg/l; GSD: 8.6 μg/l), 15% for plasma (0.09 μg/l; GSD: 0.04 μg/l), 87% for creatinine-adjusted urine and 34% for unadjusted (10.8 μg/l; GSD: 6.7 μg/l). Lead concentration in whole blood is the biomarker with the best ability to discriminate between individuals with different mean concentration. Urinary and plasma lead also performed acceptably in lead workers, but at low exposures plasma lead was too imprecise. Urinary adjustments appear not to increase the between-individual fraction of the total variance among lead workers but among those with normal lead exposure.Journal of Exposure Science and Environmental Epidemiology advance online publication, 27 February 2013; doi:10.1038/jes.2013.4.

Place, publisher, year, edition, pages
Nature Publishing Group, 2014
Keywords
biomarker, environmental exposure, lead, occupational exposure, random effect, variance between individuals
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:umu:diva-66944 (URN)10.1038/jes.2013.4 (DOI)000328604900008 ()23443239 (PubMedID)
Available from: 2013-03-08 Created: 2013-03-08 Last updated: 2018-06-08Bibliographically approved
Brorsson, C., Dahlqvist, P., Nilsson, L. & Naredi, S. (2014). Saliva stimulation with glycerine and citric acid does not affect salivary cortisol levels. Clinical Endocrinology, 81(2), 244-248
Open this publication in new window or tab >>Saliva stimulation with glycerine and citric acid does not affect salivary cortisol levels
2014 (English)In: Clinical Endocrinology, ISSN 0300-0664, E-ISSN 1365-2265, Vol. 81, no 2, p. 244-248Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE:

In critically ill patients with hypotension, who respond poorly to fluids and vasoactive drugs, cortisol insufficiency may be suspected. In serum over 90% of cortisol is protein-bound, thus routine measures of total serum cortisol may yield 'false lows' due to hypoproteinaemia. Thus, the occurrence of cortisol insufficiency could be overestimated in critically ill patients. Salivary cortisol can be used as a surrogate for free serum cortisol, but in critically ill patients saliva production is decreased, and insufficient volume of saliva for analysis is a common problem. The aim of this study was to investigate if a cotton-tipped applicator with glycerine and citric acid could be used for saliva stimulation without affecting salivary cortisol levels.

DESIGN:

Prospective, observational study.

PARTICIPANTS:

Thirty-six volunteers (six males, 30 females), age 49 ± 9 years, without known oral mucus membrane rupture in the mouth.

MEASUREMENTS:

Forty-two pairs of saliva samples (22 paired morning samples, 20 paired evening samples) were obtained before and after saliva stimulation with glycerine and citric acid. Salivary cortisol was analysed using Spectria Cortisol RIA (Orion Diagnostica, Finland).

RESULTS:

The paired samples correlated significantly (P < 0·0001) and there was no significant difference between un-stimulated and stimulated salivary cortisol levels.

CONCLUSIONS:

Saliva stimulation with a cotton-tipped applicator containing glycerine and citric acid did not significantly influence salivary cortisol levels in healthy volunteers. This indicates that salivary cortisol measurement after saliva stimulation may be a useful complement when evaluating cortisol status in critically ill patients.

National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:umu:diva-86808 (URN)10.1111/cen.12423 (DOI)000339670500013 ()24521305 (PubMedID)
Funder
Västerbotten County Council
Available from: 2014-03-11 Created: 2014-03-11 Last updated: 2019-03-06Bibliographically approved
Lindgren, C., Dahlqvist, P., Lindvall, P., Nilsson, L., Koskinen, L.-O. & Naredi, S. (2013). Cortisol levels are influenced by sedation in the acute phase after subarachnoid haemorrhage. Acta Anaesthesiologica Scandinavica, 57(4), 452-460
Open this publication in new window or tab >>Cortisol levels are influenced by sedation in the acute phase after subarachnoid haemorrhage
Show others...
2013 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 57, no 4, p. 452-460Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Subarachnoid haemorrhage (SAH) is a life-threatening condition that may be aggravated by acute pituitary damage and cortisol insufficiency. Robust diagnostic criteria for critical illness-related corticosteroid insufficiency (CIRCI) are lacking. The aim of this study was to assess the frequency of CIRCI in the acute phase (0-240 h) after SAH and to evaluate associations between cortisol levels and clinical parameters (sedation, circulatory failure, gender, age, severity of disease, treatment). CIRCI was defined as a single morning serum cortisol (mSC) < 200 nmol/L. The lower limit for calculated free cortisol (cFC) was set at < 22 nmol/L, and for saliva cortisol at < 7.7 nmol/L.

METHODS: Fifty patients were included. Serum/saliva cortisol and corticosteroid-binding globulin were obtained every second morning. A logistic regression model was used for multivariate analysis comparing cortisol levels with clinical parameters.

RESULTS: Of the patients, 21/50 (42%) had an mSC < 200 nmol/L and 30/50 (60%) had a cFC < 22 nmol/L. In patients with continuous intravenous sedation, the odds ratio for a mSC to be < 200 nmol/L was 18 times higher (95% confidence interval 4.2-85.0, P < 0.001), and the odds ratio for a cFC to be < 22 nmol/L was 2.4 times higher (95% confidence interval 1.2-4.7, P < 0.05) compared with patients with no continuous intravenous sedation.

CONCLUSIONS: Continuous intravenous sedation was significantly associated with cortisol values under defined limits (mSC < 200, cFC < 22 nmol/L). The possibility that sedating drugs per se may influence cortisol levels should be taken into consideration before CIRCI is diagnosed.

National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:umu:diva-64100 (URN)10.1111/aas.12014 (DOI)000316138800006 ()23167448 (PubMedID)
Available from: 2013-01-15 Created: 2013-01-15 Last updated: 2018-06-08Bibliographically approved
Organisations

Search in DiVA

Show all publications