Navigation and Mapping in Forest Environment Using Sparse Point Clouds

Odometry during forest operations is demanding, involving limited field of vision (FOV), back-and-forth work cycle movements, and occasional close obstacles, which create problems for state-of-the-art systems. We propose a two-phase on-board process, where tree stem registration produces a sparse point cloud (PC) which is then used for simultaneous location and mapping (SLAM). A field test was carried out using a harvester with a laser scanner and a global navigation satellite system (GNSS) performing forest thinning over a 520 m strip route. Two SLAM methods are used: The proposed sparse SLAM (sSLAM) and a standard method, LeGO-LOAM (LLOAM). A generic SLAM post-processing method is presented, which improves the odometric accuracy with a small additional processing cost. The sSLAM method uses only tree stem centers, reducing the allocated memory to approximately 1% of the total PC size. Odometry and mapping comparisons between sSLAM and LLOAM are presented. Both methods show 85% agreement in registration within 15 m of the strip road and odometric accuracy of 0.5 m per 100 m. Accuracy is evaluated by comparing the harvester location derived through odometry to locations collected by a GNSS receiver mounted on the harvester.</p

Executive function subdomains are associated with post-stroke functional outcome and permanent institutionalization

Background and purposeImpairment of executive functions (EFs) is a common cognitive symptom post-stroke and affects independence in daily activities. Previous studies have often relied on brief cognitive tests not fully considering the wide spectrum of EF subdomains. A detailed assessment of EFs was used to examine which of the subdomains and tests have the strongest predictive value on post-stroke functional outcome and institutionalization in long-term follow-up. MethodsA subsample of 62 patients from the Helsinki Stroke Aging Memory Study was evaluated with a battery of seven neuropsychological EF tests 3 months post-stroke and compared to 39 healthy control subjects. Functional impairment was evaluated with the modified Rankin Scale (mRS) and Instrumental Activities of Daily Living (IADL) scale at 3 months, and with the mRS at 15 months post-stroke. Institutionalization was reviewed from the national registers of permanent hospital admissions in up to 21-year follow-up. ResultsThe stroke group performed more poorly than the control group in multiple EF tests. Tests of inhibition, set shifting, initiation, strategy formation and processing speed were associated with the mRS and IADL scale in stroke patients. EF subdomain scores of inhibition, set shifting and processing speed were associated with functional outcome. In addition, inhibition was associated with the risk for earlier institutionalization. ConclusionsExecutive function was strongly associated with post-stroke functional impairment. In follow-up, poor inhibition was related to earlier permanent institutionalization. The results suggest the prognostic value of EF subdomains after stroke.Peer reviewe

Haptoglobin Hp1 Variant Does Not Associate with Small Vessel Disease

Haptoglobin (Hp) is a plasma protein that binds free hemoglobin and protects tissues from oxidative damage. An Hp2 allele has been associated with an increased risk of cardiovascular complications. On the other hand, recent studies have suggested that Hp1 allele increases risk to develop severe cerebral small vessel disease. We aimed to replicate this finding in a first-ever stroke patient cohort. Hp was genotyped by PCR and gel electrophoresis in the Helsinki Stroke Aging Memory Study in patients with DNA and magnetic resonance imaging (MRI) available (SAM; n = 316). Lacunar infarcts and white matter lesions (WML) classified by Fazekas grading from brain MRI were associated with Hp genotypes. As population controls, we used participants of Cardiovascular diseases-a sub study of Health 2000 Survey (n = 1417). In the SAM cohort, 63.0% of Hp1-1 carriers (n = 46), 52.5% of Hp1-2 carriers (n = 141) and 51.2% of Hp2-2 carriers (n = 129) had severe WML (p = 0.372). There was no difference in severe WMLs between Hp1-1 vs. Hp1-2 and Hp2-2 carriers (p = 0.201). In addition, 68.9% of Hp1-1 carriers (n = 45), 58.5% of Hp1-2 carriers (n = 135), and 61.8% of Hp2-2 carriers (n = 126) had one or more lacunar lesions (p = 0.472). There was no difference in the number of patients with at least one lacunar infarct between Hp1-1 vs. Hp1-2 and Hp2-2 groups (p = 0.322). Neither was there any difference when diabetic patients (type I and II) were examined separately. Hp1 allele is not associated with an increased risk for cerebral small vessel disease in a well-characterized Finnish stroke patient cohort

Tuki- ja liikuntaelinten sairauksien tutkimusmenetelmät

Osa 3. Julkaisussa: Aromaa A, Heliövaara M, Impivaara O, Knekt P, Maatela J, toim. Mini-Suomi-terveystutkimuksen toteutusTuki- ja liikuntaelinten sairauksiin kohdistuva tutkimus oli osa Mini-Suomi-tutkimusta, jossa selvitettiin 30 vuotta täyttäneiden suomalaisten terveydentilaa terveyshaastattelun ja terveystarkastuksen avulla. Maan väestöä edustavaan otokseen kuului 8 000 henkilöä. Oireita, tiedossa olevia sairauksia, sairauksien hoitoa ja seuraamuksia sekä taustatekijöitä kartoitettiin kyselyillä ja haastatteluilla. Lisäksi tehtiin niveltoimintatutkimus, yksinkertaisia lihasvoiman mittauksia ja serologisia tutkimuksia. Oireiden ja toiminnanvajavuuksien perusteella jälkitutkimukseen seulotuille tehtiin vakiomuotoinen lääkärintutkimus, jonka perusteella asetettiin diagnoosit, arvioitiin hoidon tarve ja riittävyys sekä toimintakyky. Tietoja täydennettiin haastattelemalla, lihasvoiman mittauksilla ja käsien röntgentutkimuksella. Kenttätutkimuksen jälkeen tehtiin osalle tutkituista perinpohjaisia kliinisiä tutkimuksia kenttätietojen luotettavuuden selvittämiseksi

Airborne LiDAR-derived elevation data in terrain trafficability mapping

Heavy off-road traffic causes soil compaction and rutting, which can significantly reduce the yield of forest stands. Reliable information on terrain trafficability, that is, the ability of terrain to support the passage of vehicles, would enable significant enhancement of wood procurement planning and reduction of soil damage. The objective here was to determine the feasibility of airborne scanning light detection and ranging (LiDAR)-derived digital terrain models (DTM) in terrain trafficability mapping. Soil damage was inventoried from a total of 13 km of forwarding trails, and a logistic regression model was fitted for predicting the event of soil damage. DTM-derived soil wetness indices performed well as predictor variables, and DTM-derived local binary patterns also proved useful in terrain trafficability mapping. A prediction accuracy of 83.6% (Cohen’s kappa of 0.38) was observed for soil damage probability modelling, using only DTM-derived predictors, and a corresponding accuracy of 85.0% (kappa of 0.45) was achieved when an existing soil map was used as well. In addition to the topography-related features, soil stoniness proved to be a critical factor affecting soil resistance to rutting. Our results indicate that the utilisation of LiDAR-derived elevation data for terrain trafficability mapping is a feasible method in sustainable forest management.201