| 1. |
- Granholm, Ann-Helen, et al.
(författare)
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The potential of digital surface models based on aerial images for automated vegetation mapping
- 2015
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Ingår i: International Journal of Remote Sensing. - : Informa UK Limited. - 0143-1161 .- 1366-5901. ; 36, s. 1855-1870
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Tidskriftsartikel (refereegranskat)abstract
- Segmentation of vegetation patches was tested using canopy height models (CHMs) representing the height difference between digital surface models (DSMs), generated by matching digital aerial images from the Z/I Digital Mapping Camera, and a digital elevation model (DEM) based on airborne laser scanner data. Three different combinations of aerial images were used in the production of the CHMs to test the effect of flight altitude and stereo overlap on segmentation accuracy. Segmentation results were evaluated using the standard deviation of photo-interpreted tree height within segments, as well as by visual comparison to existing maps. In addition, height percentiles extracted from the CHMs were used to estimate tree heights. Tree height estimation at the segment level yielded root mean square error (RMSE) values of 2.0 m, or 15.1%, and an adjusted coefficient of determination (adjusted R2) of 0.94 when using a CHM from images acquired at an altitude of 1200 m above ground level (agl) and with an along-track stereo overlap of 80%. When a CHM based on images acquired at 4800 m agl and an overlap of 60% was used, the corresponding results were an RMSE of 2.2 m, or 16.0%, and an adjusted R2 of 0.92. Tree height estimation at the plot level was most accurate for densely forested plots dominated by coniferous tree species (RMSE of 2.1 m, or 9.8%, and adjusted R2 of 0.88). It is shown that CHMs based on aerial images acquired at 4800 m agl and with 60% along-track stereo overlap are useful for the segmentation of vegetation and are at least as good as those based on aerial images collected at a lower flight altitude or with greater overlap.
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| 2. |
- Holmgren, Helén, 1970-
(författare)
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Case i bokföring
- 2013
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Bok (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Holmgren, Helén, 1970-, et al.
(författare)
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Case i bokföring
- 2020. - 2
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Bok (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Holmgren, Helén, 1970-, et al.
(författare)
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Case i redovisning
- 2023. - 3
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Bok (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Holmgren, Helen, 1970, et al.
(författare)
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Variation Theory as Teaching Method in Introductory Accounting Courses - Effects on Student Learning
- 2017
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Ingår i: 40th Annual Congress of the European Accounting Association 2017. 10-12 May 2017, Valencia, Spain..
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Konferensbidrag (refereegranskat)abstract
- In this paper we study effects on student learning from a systematic use of variation theory in the structure of lectures. We study three introductory financial accounting courses in the 2015-16 academic year. Students are randomly assigned to groups, where the treatment group is exposed to a lecture based on variation theory, and the control group is exposed to a traditional lecture. We measure student understanding both before and after the course, using both essay questions and multiple choice questions. The understanding that we focus on is the link between balance sheet measurement and net income, and the relation to stakeholder incentives and interests. We hypothesize and find that students in the treatment group have a better understanding of financial accounting. We also note that essay questions are more effective than multiple choice questions in measuring understanding. In addition, it may be important to consider pre-study experience of accounting (e.g. through work experience), as this has a substantial impact on the level of understanding.
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| 6. |
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| 7. |
- Nordkvist, Karin, et al.
(författare)
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Classification of EBONE General Habitat Categories in a Swedish forest area by using LiDAR in combination with SPOT satellite data
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We have investigated to which degree a combination of optical satellite data and LiDAR data can improve classification accuracy of the General Habitat Categories (GHC) used by the FP7 project European Biodiversity Observation Network (EBONE), compared to using satellite data alone. The study was carried out in Remningstorp, a forest dominated area in southern Sweden. Remote sensing data used in the study were a SPOT 5 image from August 2009 and a laser scanning (26 points/m2) from September 2008. Ground truth samples were collected by interpretation of color infrared digital air photos from September 2009. Maximum likelihood and Random Forests classifications were made with satellite data and with a combination of satellite and LiDAR data. The classification scheme consisted of six forest classes, arable land and pasture land. The use of LiDAR data improved over-all accuracy with 6% for maximum likelihood classification and 7% for Random Forests. The highest over-all accuracy was obtained with Random Forests, but on the expense of the smaller classes.
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| 8. |
- Nordkvist, Karin, et al.
(författare)
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Combining optical satellite data and airborne laser scanner data for vegetation classification
- 2012
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Ingår i: Remote Sensing Letters. - : Informa UK Limited. - 2150-704X .- 2150-7058. ; 3, s. 393-401
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate to which degree the accuracy of vegetation classification could be improved by combining optical satellite data and airborne laser scanner (ALS) data, compared with using satellite data only. A Satellite Pour l'Observation de la Terre (SPOT) 5 scene and Leica ALS 50-II data from 2009, covering a test area in the mid-Sweden (latitude 60 degrees 43' N, longitude 16 degrees 43' E), were used in maximum likelihood and decision tree classifications. Training and validation data were obtained from the interpretation of digital aerial photo stereo models. Combination of SPOT and ALS data gave classification accuracies up to 72%, compared with 56% using only SPOT data. This indicates that integrating features from large area laser scanning may lead to significant improvements in satellite data-based vegetation classifications.
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| 9. |
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| 10. |
- Vrethem, Magnus, et al.
(författare)
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Correlation between dynamic posturography, clinical investigation, and neurography in patients with polyneuropathy
- 1991
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Ingår i: Journal for Oto-Rhino-Laryngology. - : S. Karger AG. - 0301-1569 .- 1423-0275. ; 53:5, s. 294-298
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic posturography (PG) is a new objective method to study functional performance in diseases affecting balance. It measures muscle response latencies and sway angles to standardized alterations of a moveable platform and moveable surroundings. Twenty-eight patients with polyneuropathy (PN) were studied by clinical investigation, vibrametry, neurography, and dynamic PG. The results of dynamic PG and vibrametry were compared with those of 29 healthy controls. In the patients with PN, clinical scores correlated to the latencies of the muscle response when the platform was suddenly moved forward, and to equilibrium performance (sway angles) in dynamic PG test conditions with eyes closed and the platform either stable or ‘sway-referenced’. That is, the platform moves in response to the patient’s anterior-posterior sway, creating a disturbed proprioceptive input to the brain. Clinical scores also correlated to the equilibrium performance when both platform and surroundings were sway-referenced. In conclusion dynamic PG, in addition to clinical investigations and neurophysiology, is a valuable and objective method for estimating the equilibrium performance in patients with PN.
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| 11. |
- Vrethem, Magnus, 1955-, et al.
(författare)
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Painful polyneuropathy in patients with and without diabetes : Clinical, neurophysiologic, and quantitative sensory characteristics
- 2002
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Ingår i: The Clinical Journal of Pain. - : Ovid Technologies (Wolters Kluwer Health). - 0749-8047 .- 1536-5409. ; 18:2, s. 122-127
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To study pain characteristics and peripheral nerve involvement in patients with painful diabetic and nondiabetic polyneuropathy in comparison with patients with nonpainful polyneuropathy. Patients and Methods: Fifty-five patients with polyneuropathy (37 with painful polyneuropathy, of whom 19 had diabetes and 18 had no diabetes, and 18 with painless polyneuropathy of different etiologies) were examined clinically using quantitative sensory tests and neurophysiology. Pain intensity and characteristics were analyzed by daily ratings on a 10-step verbal scale and by a questionnaire. Results: Most patients experienced pain of more than one character. There was no clear difference in character or duration of pain between patients with and without diabetes. The mean value of the daily rating of pain intensity showed that pain was more severe in the evenings than in the mornings and that diabetic patients reported worse pain than nondiabetic patients. Thirty-two of the 37 patients with pain had paresthesias and/or dysesthesias, whereas only 7 of 18 patients without pain had paresthesias. Pain was always located in the feet, and, in most patients, also in the lower part of the legs. Some patients also experienced pain in the hands. Tactile sensibility, measured by quantitative tests, was more affected in both diabetic and nondiabetic patients with painful polyneuropathy compared with patients without pain (p = 0.02). Temperature, pain, and vibratory sensibility were equally affected in all patient groups. Nerve conduction velocity, amplitudes, and distal latency were equally affected in the pain group as compared with the control group, indicating that both thin and thick nerve afferents are affected in patients with painful as well as nonpainful polyneuropathy and that etiology has no clear impact on nerve involvement. Conclusions: Neuropathy pain was always located in the feet and more severe in diabetic patients compared with patients with neuropathy pain of other etiologies. The authors also found evidence for a greater tactile sensibility involvement in patients with neuropathy pain, irrespective of etiology, whereas other quantitative sensibility and neurography parameters were equally affected in all patient groups.
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| 12. |
- Österlund, Barbro, et al.
(författare)
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Surgical stress induces acute coronary release of tissue-type plasminogen activator in the pig
- 2000
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Ingår i: Acta Anaesthesiol Scand. ; 44:10, s. 1226-31
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Tissue-type plasminogen activator (t-PA) is an endothelium derived key enzyme in the initiation of endogenous fibrinolysis. Acute regulated release of active t-PA occurs within minutes in response to threatening thrombotic vessel occlusion. The aim of this study was to investigate the impact of surgical stimulation on the kinetics of t-PA release in the coronary vascular bed in the pig. METHODS: In anaesthetised pigs (n=16), arterio-venous concentration gradients of t-PA, and plasma flows (retrograde thermodilution) were obtained across the coronary vascular bed before (control) and at 1, 3, 5 and 10 min after sternotomy. RESULTS: At control, no significant coronary net flux (release or uptake) of t-PA was observed, while sternotomy induced a rapid net release of total t-PA (132.6 ng x min(-1)), with an associated increase in active t-PA (93.6 ng x min(-1)). This response, evident already after 1 min, showed a peak at 5 min and returned towards baseline levels within 10 min. No concurrent alterations in aortic levels of active t-PA were found and haemodynamic variables were unaltered. CONCLUSION: The rapidly increasing and transient net coronary release of t-PA after sternotomy suggests that the endothelium actively promotes local endogenous fibrinolysis during surgery. Such events could reflect a dynamic responsiveness to protect the coronary circulation during stress.
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