| 1. |
- Wang, Dong V., et al.
(författare)
-
Disrupting Glutamate Co-transmission Does Not Affect Acquisition of Conditioned Behavior Reinforced by Dopamine Neuron Activation
- 2017
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 18:11, s. 2584-2591
-
Tidskriftsartikel (refereegranskat)abstract
- Dopamine neurons in the ventral tegmental area (VTA) were previously found to express vesicular glutamate transporter 2 (VGLUT2) and to co-transmit glutamate in the ventral striatum (VStr). This capacity may play an important role in reinforcement learning. Although it is known that activation of the VTA-VStr dopamine system readily reinforces behavior, little is known about the role of glutamate co-transmission in such reinforcement. By combining electrode recording and optogenetics, we found that stimulation of VTA dopamine neurons in vivo evoked fast excitatory responses in many VStr neurons of adult mice. Whereas conditional knockout of the gene encoding VGLUT2 in dopamine neurons largely eliminated fast excitatory responses, it had little effect on the acquisition of conditioned responses reinforced by dopamine neuron activation. Therefore, glutamate co-transmission appears dispensable for acquisition of conditioned responding reinforced by DA neuron activation.
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| 2. |
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| 3. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
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Appraisal methodology : Deliverable D2.1
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report represents INFRACOMS deliverable D2.1 Appraisal Methodology. It builds upon the deliverables of INFRACOMS Work Package 1 which identified the information needs, gaps and priorities of NRAs in terms of their approach to data collection and monitoring, and a list of current and emerging measurement technologies. This report includes a review of several commonly-used appraisal methodologies that can be used to evaluate the effectiveness, suitability and potential impact of new technologies for an organisation. These methodologies include Technology Readiness Levels (TRLs), Cost Benefit Analysis (CBA), Life Cycle Cost Analysis (LCCA), Risk Assessment, and Multi-Criteria Decision Analysis (MCDA). Elements of these commonly used methodologies are included in the INFRACOMS Appraisal Methodology. The report also includes key highlights from a workshop with NRAs conducted in January 2023 which also fed into the design of the appraisal methodology. The INFRACOMS Appraisal Methodology described here is designed around the technology use case, that is, a particular application of a technology by a NRA. It incorporates three core processes for Pre-Evaluation, Evaluation and Case Studies of technology use cases. It also includes processes for NRAs to define their strategic and technical priorities so that the appraisal process can be tailored to addressing their individual requirements, as identified from Work Package 1.
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| 4. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
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Current Practice, Future need and Gap Analysis : Deliverable D1.1
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is INFRACOMS first deliverable D1.1. It addresses the “Understanding of information needs and gaps” component of the project. The aim has been to identify the current priorities and future needs of NRAs for the management of carriageway and bridge assets, specifically in terms of their approach to data collection and monitoring. The approach has been to establish existing knowledge via a review of previous projects, current best practices and standards in data collection and inspection, and a review of current business processes, NRA strategies around data collection and digitalisation etc. The report identifies a set of key imperatives for carriageway and bridge assets covering Availability, Reliability, Environment, Economy and Safety. Each of these is supported by the collection of key condition data, which is used to report technical parameters and performance indicators that can be combined to assess the ability of the asset to meet its key imperatives. A wide range of technologies are identified, which are currently applied to collect the data that supports this assessment.The consultation shows that there are also gaps between the desired and the current capability for the assessment of these assets. These include gaps in the data, challenges in the ability to collect the data, gaps in the application of the data that is already collected etc. A review of emerging technologies shows that there are tools and technologies that could help to fill these gaps. These could overcome the limitations of current technologies, better integrate new data sources, provide greater flexibility in using current and new data, and provide better analysis. They include remote sensing, Internet of Things (IoT), crowdsourcing, and advanced data processing/visualisation.
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| 5. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
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Friktion- och makrotexturutveckling på nya beläggningar : verifiering av tidigare resultat
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vägens friktion är troligen den egenskap hos vägen som har störst betydelse för trafiksäkerheten. När en ny beläggning läggs varnas trafikanterna normalt genom skyltning med varningsmärket A10 ”Varning för slirig väg”, med tilläggstavla T22, ”Vid våt vägbana”. Skyltningen utförs som en säkerhetsåtgärd. Huvudsyftet med detta projekt har varit att verifiera resultaten från den första studien, för att veta hur friktionen förändras efter trafikpåsläpp på en nyasfalterad väg. Ambitionen var att kunna avgöra om nylagda vägavsnitt har nedsatt friktion för att kunna ge rekommendationer hur skyltning till trafikanter ska ske i samband med och efter beläggningsarbeten och nybyggnationer. I denna kompletterande studie mättes friktion och makrotextur på vägar med olika nylagda beläggningar från strax innan trafikpåsläpp till dess makrotextur- och friktionsnivåerna hade stabiliserats. De tre beläggningstyper som studerades var Asfaltbetong stenrik (ABS), Asfaltbetong tät (ABT) och Mjukbitumenbundet grus med oljegrusgradering (MJOG). Ett av objekten specialstuderades genom upprepade avgjutningar och fotografering av en specifik kontrollyta för att försöka avgöra hur vägytan förändras över tid. Denna studie bekräftar mycket av vad som framkom i den tidigare studien. En ny beläggning har den högsta friktionen i samband med att trafiken släpps på. Därefter minskar friktionen under de kommande veckorna innan den börjar öka igen för att vara stabiliserad efter ungefär fem veckor. Detta var fallet för två av beläggningstyperna (ABS och ABT). Sträckan med MJOG var stabil redan efter tre veckor. Den normala tiden innan makrotexturnivåerna stabiliserades var mellan fyra och fem veckor. Även där fanns det en viss variation mellan de olika beläggningstyperna. Det visade sig även att det kan skilja sig i friktion mellan en konventionell beläggning och en remixad beläggning.
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| 6. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
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Friktions- och texturutveckling på nya beläggningar
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En ny vägyta bör vara och upplevas som säker av trafikanterna oavsett vilket väglag som råder. Det är därför viktigt att vägbanan har en tillfredställande nivå på friktion redan när vägen öppnas. Det finns begränsade dokumenterade kunskaper hur vägen förändras den första tiden efter en beläggningsåtgärd.Syftet med detta projekt är att fastställa hur friktionen förändras under den första tiden efter att vägbeläggningen är lagd och trafikpåsläpp sker. Ambitionen är att kunna avgöra om nylagda vägavsnitt har nedsatt friktion och ge rekommendationer för när en friktionsmätning ska utföras och hur skyltning ska ske i anslutning till beläggningsarbeten. Upplägget har varit att följa olika objekt med täta friktions- och texturmätningar från strax innan trafikpåsläpp tills nivåerna har stabiliserats.Initialt är friktionen hög för att sen avta med mängden trafik. Efter 1–3 veckor nåddes det lägsta värdet och därefter ökade eller stabiliserades friktionen. Gemensamt för alla undersökta sträckor var att det sker stora förändringar i texturnivåerna från att det första fordonet trafikerar vägen och därefter är den starkaste tendensen en sjunkande texturnivå tills en stabil nivå uppnås efter 1–3 veckor.
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| 7. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
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Report on state-of-the-art data assessment and visualisation methods : Deliverable D3.1
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Effective analysis and visualisation of data is critical for the efficient application of the data provided by carriageway and bridge condition monitoring technologies. It supports better decisions in relation to asset reliability, availability, safety, economy and environment. This report discusses the link between the data provided by monitoring technologies on the properties of assets and how the collected data can be analysed and visualised to provide value in decision support. The next step in the report is to use this understanding to develop an appraisal system which could enable technologies in the INFRACOMS technology database to be appraised (scored) in relation to their abilities for data analysis, visualisation, integration and use in decision support.The presented system is referred to as the D3.1 scoring system. It consists of four components covering data visualisation, data analysis, integration within current data architectures and potential for practical decision-making. The present D3.1 report primarily examines the components pertaining to data visualisation and data analysis, while the exploration of the other two components, data architecture and decision support, will be carried out in the D3.2 report. It is proposed that the D3.1 scoring system could be used to appraise the capability of monitoring technologies to support asset management decisions, and would become an integral component of the INFRACOMS Appraisal Toolkit. It will also be used to further filter the current INFRACOMS Technology Database 2.0 technologies as part of the Appraisal Toolkit as INFRACOMS completes the development of the toolkit/database within WP2.
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| 8. |
- Arvidsson, Anna K, et al.
(författare)
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Test av korrektionstjänst för GPS-mottagare vid vägytemätning
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En mycket viktig faktor vid inventering av vägnätets tillstånd med hjälp av mätbilar är att med tillräckligt bra noggrannhet kunna positionsbestämma mätdata.I mars 2012 lades korrektionstjänsten EPOS, som hittills använts för att ge en förbättrad positionering, ner. I och med detta har VTI på uppdrag av Trafikverket utvärderat om den kostnadsfria korrektionstjänsten EGNOS, som drivs av ESA, är möjlig att använda istället. Svaret är ja. Inga systematiska skillnader i positionsangivelser har kunnat observeras då den gamla och nya korrektionstjänsten använts.
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| 9. |
- Arvidsson, Anna K., 1971-, et al.
(författare)
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Åkkvalitet på vinterväg
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna VTI-studie konstaterar att det går att mäta ojämnheter på vinterväg på samma sätt som på barmarksväg. Både ojämnheter och buller vid låga frekvenser ökar vid visst vinterväglag och är kopplade till hastighet. De mätningar som utförts inom projektets ramar visar att det går utmärkt att utföra mätningar på en snöklädd yta. Med vinterväglag menas här en snöklädd väg cirka ett dygn efter ett kraftigt snöfall. Baserat på de vägar som mättes visar studien att ojämnheter i våglängdsintervallet 0,05 till 1 meter påverkas allra mest av vinterväglaget. Ojämnheterna ökar cirka 5 gånger i medeltal för hela testslingan från barmarks- till vinterförhållanden. Det går även att se att ytans struktur, som beskrivs av de kortaste våglängderna som undersöktes, <10 mm, blir slätare på den snöklädda ytan vilket var en av hypoteserna och som indikerar att mätningen är pålitlig. Kopplingen mellan buller och ojämnheter är relaterade till hastighet. Den största ljudskillnaden mellan vinter- och sommarväg var vid låga frekvenser. Det uppfattade ljudet i bilen var då mellan 3 och 6 decibel högre för körningen på vinterväg. I de mer högfrekventa områdena var skillnaden i ljudnivå tvärtom, lägre för vintervägen än för sommarvägen och en trolig orsak till detta kan vara att ljudet absorberas av snön.
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| 10. |
- Arvidsson, Emma, 1986-, et al.
(författare)
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Age- and Sex-Dependence of Dopamine Release and Capacity for Recovery Identified in the Dorsal Striatum ofC57/Bl6J Mice
- 2014
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:6, s. e99592-
-
Tidskriftsartikel (refereegranskat)abstract
- The dorsal striatum is the main input structure of the basal ganglia and the major target area of dopaminergic projections originating in the substantia nigra pars compacta. Heavily involved in the regulation of voluntary movement and habit formation, this structure is of strong importance in Parkinson's disease, obsessive-compulsive disorder, Tourette's syndrome and addiction. The C57/Bl6J mouse strain, the most commonly used strain in preclinical research today, is frequently used as a model organism for analysis of dopaminergic parameters implicated in human pathophysiology. Several components of the dopamine system have been shown to vary with age and sex, however knowledge of the contribution of these factors for dopamine release kinetics in the C57/Bl6J mouse strain is lacking. In the present study, we used an intracranial KCl-stimulation challenge paradigm to provoke release from dopaminergic terminals in the dorsal striatum of anaesthetized C57/Bl6J mice. By high-speed in vivo chronoamperometric recordings, we analyzed DA release parameters in male and female mice of two different ages. Our experiments demonstrate elevated DA amplitudes in adult compared to young mice of both sexes and higher DA amplitudes in females compared to males at both ages. Adult mice exhibited higher recovery capabilities after repeated stimulation than did young mice and also showed a lower variability in the kinetic parameters trise and t80 between stimulations. These results identified age- and sex- dimorphisms in DA release parameters and point to the importance of taking these dimorphisms into account when utilizing the C57/Bl6J mouse strain as model for neurological and neuropsychiatric disorders.
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| 11. |
- Arvidsson, Johan, et al.
(författare)
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Comparing penetrometer and shear vane measurements with measured and predicted mouldboard plough draught in a range of Swedish soils
- 2011
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Ingår i: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 111, s. 219-223
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Tidskriftsartikel (refereegranskat)abstract
- Soil strength proved much more sensitive to changes in water content than draught requirement. Consequently, model predictions of specific draught were much higher than measured values in soil with high cohesion values. A possible explanation is that specific draught mainly depends on inter-aggregate strength, while the intra-aggregate strength may be considerably higher. Over all tillage occasions, specific draught was much more strongly correlated to cohesion than to penetration resistance. There was also a clear correlation between draught and soil clay content. Multiple regression including cohesion and soil water content resulted in a much higher coefficient of determination than regression with cohesion only. The results indicate that neither shear vane nor penetrometer measurements are sufficient to predict draught requirement, and it is desirable to develop a simple yet reliable field method that can be used for this purpose. More general estimates of fuel consumption can probably be made based on the soil clay content only. (C) 2010 Elsevier B.V. All rights reserved.
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| 12. |
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| 13. |
- Arvidsson, Johan, et al.
(författare)
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Draught requirement during tillage
- 2010
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Ingår i: Soil Engineering. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783642036804 ; 20:20, s. 3-17
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 14. |
- Arvidsson, Johan, et al.
(författare)
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Rubber track systems for conventional tractors : Effects on soil compaction and traction
- 2011
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Ingår i: Soil & Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 117, s. 103-109
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Tidskriftsartikel (refereegranskat)abstract
- Traditionally, tractors have been built either for tracks or wheels, with tracks mainly on heavy tractors with high power. Today, it is possible to retrofit four separate track units on a conventional agricultural tractor, creating interesting possibilities for agriculture. The objective of the present study was to compare soil compaction and traction for tracks, single and dual wheels mounted on the same tractor type. Measurements were made on two clay soils (Eutric Cambisols) in Sweden in 2009, using an 85kW tractor with a total weight of 7700kg. The rubber track system consisted of four tracks mounted on the conventional wheel axles of the tractor. The measured stresses were similar for the tracks and dual wheels at all depths studied (15, 30 and 50cm), but were considerably higher for the single wheels at all depths. Simulations of soil stresses correlated closely to measured values for the tracks and the dual wheels, but underestimated soil stresses in the topsoil compared to measured values for the single wheel. Bulk density and penetration resistance were consistently highest and saturated hydraulic conductivity lowest after wheeling with single wheels, while there were no statistically significant differences between tracks and dual wheels. With single wheels and the tractor loaded, saturated hydraulic conductivity decreased to 0.01mh-1 from 0.13mh-1 in the control, while bulk density increased from 1.24 to 1.36Mgm-3. The stress distribution in the driving direction was relatively even along the front and rear tracks, which is an advantage compared with a long single track, which often has an uneven longitudinal stress distribution. Slip was significantly higher for the dual and single wheels compared with tracks. To utilise the large contact area of the tracks, the tractor should have a low weight in relation to the engine power. © 2011 Elsevier B.V.
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| 15. |
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| 16. |
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| 17. |
- Arvidsson, Niklas, et al.
(författare)
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Cirkulära möbelflöden : Hur nya affärsmodeller kan bidra till hållbar utveckling inom offentliga möbler
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige har en stark möbelindustri och en stolt tradition av att tillverka tidlösa och högkvalitativa möbler, ofta av naturmaterial. 2016 producerade Sverige möbler för 22,8 miljarder SEK, varav kontorsmöbler stod för nästan en fjärdedel1. Det saknas idag statistik över vad som händer med dessa möbler när de inte längre används, men det står klart att många av dem slängs i förtid när verksamheter flyttar eller när deras behov ändras. Samtidigt syns en tydlig utveckling mot att kunder mer och mer efterfrågar återbrukade eller renoverade möbler som en del i sitt hållbarhetsarbete. Denna utveckling var startpunkten för projektet ”Affärsmodell-innovation för cirkulära möbelflöden”. Affärsmodellinnovation för cirkulära möbelflöden är ett Vinnovafinansierat projekt som under åren 2015-2017 arbetat med att utveckla och testa koncept för cirkulära affärsmodeller för i första hand offentliga möbler. I projektet har tjugo aktörer från hela värdekedjan, från underleverantörer, möbelproducenter, återförsäljare och användare till forskare och branschorgan, samarbetat kring affärsutveckling, kundincitament, produktdesign, logistik, hållbarhets- och certifieringsfrågor. Den här skriften belyser hur nya affärsmodeller för mer cirkulära möbelflöden kan bidra till en mer hållbar utveckling och ger smakprov på slutsatser från projektet. Skriften riktar sig framför allt till producenter och återförsäljare av möbler för offentliga miljöer, men även kunder och inköpare tror vi kan ha stor nytta av skriften. Vi hoppas att den även kan fungera som inspiration för andra industrier och branscher som funderar på en övergång till mer cirkulära affärsekosystem.
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| 18. |
- Arvidsson, Thomas, et al.
(författare)
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Autism in 3-6-Year-Old Children in a Suburb of Goteborg, Sweden
- 1997
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Ingår i: Autism. - : SAGE Publications. - 1362-3613 .- 1461-7005. ; 1:2, s. 163-173
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Tidskriftsartikel (refereegranskat)abstract
- 1941 ofthe 3-6-year-old children living in a community outside Gbteborg on the Swedish west coast were screened with a view to identifying all individuals with severe degrees of autistic behaviour. All children in the population were known to well baby clinic staff, and any child suspected of suffering from autism was referred to a specialized clinical research team. The nurses and doctors working in the well baby clinics were well informed about autism. Clinical and ADI-R diagnoses of autism were established after thorough clinical assessments of each suspected case. All children were seen at least twice, and all were over the age of 3 years at the time of diagnosis. The general population prevalence for autism was 3 I in I o,ooo children (9; percent confidence interval 7/ g;). Classic Kanner autism was found in I o in Io,ooo children (9; percent confidence interval-4/24). These rates appear to reflect higher rates than previously reported. Some reasons for the possibly higher prevalence are discussed.
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| 19. |
- Björck, Lennart, et al.
(författare)
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Tveksam vinst med ekolantbruk
- 2009
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Ingår i: Svenska dagbladet. - 1101-2412. ; -
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 20. |
- Bonagas, Nadilly, et al.
(författare)
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Pharmacological targeting of MTHFD2 suppresses acute myeloid leukemia by inducing thymidine depletion and replication stress
- 2022
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Ingår i: NATURE CANCER. - : Springer Science and Business Media LLC. - 2662-1347. ; 3:2, s. 156-
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Tidskriftsartikel (refereegranskat)abstract
- The folate metabolism enzyme MTHFD2 (methylenetetrahydrofolate dehydrogenase/cyclohydrolase) is consistently overexpressed in cancer but its roles are not fully characterized, and current candidate inhibitors have limited potency for clinical development. In the present study, we demonstrate a role for MTHFD2 in DNA replication and genomic stability in cancer cells, and perform a drug screen to identify potent and selective nanomolar MTHFD2 inhibitors; protein cocrystal structures demonstrated binding to the active site of MTHFD2 and target engagement. MTHFD2 inhibitors reduced replication fork speed and induced replication stress followed by S-phase arrest and apoptosis of acute myeloid leukemia cells in vitro and in vivo, with a therapeutic window spanning four orders of magnitude compared with nontumorigenic cells. Mechanistically, MTHFD2 inhibitors prevented thymidine production leading to misincorporation of uracil into DNA and replication stress. Overall, these results demonstrate a functional link between MTHFD2-dependent cancer metabolism and replication stress that can be exploited therapeutically with this new class of inhibitors. Helleday and colleagues describe a nanomolar MTHFD2 inhibitor that causes replication stress and DNA damage accumulation in cancer cells via thymidine depletion, demonstrating a potential therapeutic strategy in AML tumors in vivo.
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| 21. |
- Diamond, Miriam, et al.
(författare)
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Exploring the planetary boundary for chemical pollution
- 2015
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 78, s. 8-15
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Forskningsöversikt (refereegranskat)abstract
- Rockström et al. (2009a, 2009b) have warned that humanity must reduce anthropogenic impacts defined by nine planetary boundaries if “unacceptable global change” is to be avoided. Chemical pollution was identified as one of those boundaries for which continued impacts could erode the resilience of ecosystems and humanity. The central concept of the planetary boundary (or boundaries) for chemical pollution (PBCP or PBCPs) is that the Earth has a finite assimilative capacity for chemical pollution, which includes persistent, as well as readily degradable chemicals released at local to regional scales, which in aggregate threaten ecosystem and human viability. The PBCP allows humanity to explicitly address the increasingly global aspects of chemical pollution throughout a chemical's life cycle and the need for a global response of internationally coordinated control measures. We submit that sufficient evidence shows stresses on ecosystem and human health at local to global scales, suggesting that conditions are transgressing the safe operating space delimited by a PBCP. As such, current local to global pollution control measures are insufficient. However, while the PBCP is an important conceptual step forward, at this point single or multiple PBCPs are challenging to operationalize due to the extremely large number of commercial chemicals or mixtures of chemicals that cause myriad adverse effects to innumerable species and ecosystems, and the complex linkages between emissions, environmental concentrations, exposures and adverse effects. As well, the normative nature of a PBCP presents challenges of negotiating pollution limits amongst societal groups with differing viewpoints. Thus, a combination of approaches is recommended as follows: develop indicators of chemical pollution, for both control and response variables, that will aid in quantifying a PBCP(s) and gauging progress towards reducing chemical pollution; develop new technologies and technical and social approaches to mitigate global chemical pollution that emphasize a preventative approach; coordinate pollution control and sustainability efforts; and facilitate implementation of multiple (and potentially decentralized) control efforts involving scientists, civil society, government, non-governmental organizations and international bodies.
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| 22. |
- Elmsjö, Albert, 1986-
(författare)
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Selectivity in NMR and LC-MS Metabolomics : The Importance of Sample Preparation and Separation, and how to Measure Selectivity in LC-MS Metabolomics.
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Until now, most metabolomics protocols have been optimized towards high sample throughput and high metabolite coverage, parameters considered to be highly important for identifying influenced biological pathways and to generate as many potential biomarkers as possible. From an analytical point of view this can be troubling, as neither sample throughput nor the number of signals relates to actual quality of the detected signals/metabolites. However, a method’s selectivity for a specific signal/metabolite is often closely associated to the quality of that signal, yet this is a parameter often neglected in metabolomics.This thesis demonstrates the importance of considering selectivity when developing NMR and LC-MS metabolomics methods, and introduces a novel approach for measuring chromatographic and signal selectivity in LC-MS metabolomics.Selectivity for various sample preparations and HILIC stationary phases was compared. The choice of sample preparation affected the selectivity in both NMR and LC-MS. For the stationary phases, selectivity differences related primarily to retention differences of unwanted matrix components, e.g. inorganic salts or glycerophospholipids. Metabolites co-eluting with these matrix components often showed an incorrect quantitative signal, due to an influenced ionization efficiency and/or adduct formation.A novel approach for measuring selectivity in LC-MS metabolomics has been introduced. By dividing the intensity of each feature (a unique mass at a specific retention time) with the total intensity of the co-eluting features, a ratio representing the combined chromatographic (amount of co-elution) and signal (e.g. in-source fragmentation) selectivity is acquired. The calculated co-feature ratios have successfully been used to compare the selectivity of sample preparations and HILIC stationary phases.In conclusion, standard approaches in metabolomics research might be unwise, as each metabolomics investigation is often unique. The methods used should be adapted for the research question at hand, primarily based on any key metabolites, as well as the type of sample to be analyzed. Increased selectivity, through proper choice of analytical methods, may reduce the risks of matrix-associated effects and thereby reduce the false positive and false negative discovery rate of any metabolomics investigation.
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| 23. |
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| 24. |
- Etana, Ararso, et al.
(författare)
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Persistent subsoil compaction and its effects on preferential flow patterns in a loamy till soil
- 2013
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 192, s. 430-436
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Tidskriftsartikel (refereegranskat)abstract
- Persistence of subsoil compaction was investigated in a field experiment in southern Sweden. The investigation compared two treatments (control and compaction by four passes track-by-track), 14 years after the experimental traffic. The compaction experiment was carried out in 1995 with a 6-row sugar beet harvester with a wheel load of c. 10.4 Mg. Investigations included penetration resistance, bulk density, water retention, saturated hydraulic conductivity, in situ near-saturated hydraulic conductivity, and dye tracing experiments. The measurements of penetration resistance and bulk density clearly showed the persistence of subsoil compaction. In addition, both macroporosity and saturated and near-saturated hydraulic conductivity were smaller in the compacted plots, although these differences were not statistically significant. Dye tracing allowed us to visualize flow patterns in the soil and to quantitatively distinguish compacted and non-compacted subsoil profiles. Despite significant soil textural heterogeneity across the experimental field, the dye tracing data showed that persistent compaction may enhance preferential flow. (C) 2012 Elsevier B.V. All rights reserved.
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| 25. |
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| 26. |
- Forslund, Dick, 1953-
(författare)
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Hit med pengarna! : Sparandets genealogi och den finansiella övertalningens vetandekonst
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Idag pågår i hela västvärlden försök att finansiellt utbilda allmänheten. Vi möts överallt av finansiell reklam. I de nya budskapen om bra finansiellt beteende finns en ny slags moralism – det är tesen i denna avhandlings kritiska genealogi över penningsparandets påbjudna sanningar, moral och känsloliv under två århundraden. Vilka är de nya sanningarna? Men framför allt: Vilka är det rätta känslorna för den enskilde att idag odla i förhållande till det finansiella systemet? Maktutövande övertalning-undervisning i privatekonomiska frågor inriktas på det mottagande subjektets känsloliv. Avhandlingens styrande fråga är: Hur känns mötet med dagens finansiella reklam och folkbildningsförsök? Frågan överskrider analyser av maktutövning i och med språket som, i Michel Foucaults efterföljd, inriktas på tänkande och rationalitet.Ett kvantifierande system grundas i känsla som ytterst styr dess tolkningssystem: systemets subjektiveringssida. Ett generiskt subjekt är tolkningssystemets optimerande ledare. Vår relation till det präglas av ett tillkortakommande. Avhandlingen talar ofta ur detta imaginära subjekts mun, i inkännande tolkning av ”jag” i nutida reklam och folkbildningstexter.I det nya talet om hushållsekonomi framhålls finansiell stoicism som ett ideal. Det finansiella systemet är inte amoraliskt. Det är ett centralt moraliskt system i våra samhällen. Pengar är samhällets viktigaste organisationsmedel, hierarkiseringsmedel och uppfostringsmedel. I avhandlingen framträder till slut utropet, kravet och rådet ”Hit med pengarna!” som det undersökta tolkningssystemets kärnutsaga.
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| 27. |
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| 28. |
- Halliday, Alison, et al.
(författare)
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10-year stroke prevention after successful carotid endarterectomy for asymptomatic stenosis (ACST-1) : A multicentre randomised trial
- 2010
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 376:9746, s. 1074-1084
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Tidskriftsartikel (refereegranskat)abstract
- Background If carotid artery narrowing remains asymptomatic (ie, has caused no recent stroke or other neurological symptoms), successful carotid endarterectomy (CEA) reduces stroke incidence for some years. We assessed the long-term effects of successful CEA. Methods Between 1993 and 2003, 3120 asymptomatic patients from 126 centres in 30 countries were allocated equally, by blinded minimised randomisation, to immediate CEA (median delay 1 month, IQR 0·3-2·5) or to indefinite deferral of any carotid procedure, and were followed up until death or for a median among survivors of 9 years (IQR 6-11). The primary outcomes were perioperative mortality and morbidity (death or stroke within 30 days) and non-perioperative stroke. Kaplan-Meier percentages and logrank p values are from intention-to-treat analyses. This study is registered, number ISRCTN26156392. Findings 1560 patients were allocated immediate CEA versus 1560 allocated deferral of any carotid procedure. The proportions operated on while still asymptomatic were 89·7 versus 4·8 at 1 year (and 92·1 vs 16·5 at 5 years). Perioperative risk of stroke or death within 30 days was 3·0 (95 CI 2·4-3·9; 26 non-disabling strokes plus 34 disabling or fatal perioperative events in 1979 CEAs). Excluding perioperative events and non-stroke mortality, stroke risks (immediate vs deferred CEA) were 4·1 versus 10·0 at 5 years (gain 5·9, 95 CI 4·0-7·8) and 10·8 versus 16·9 at 10 years (gain 6·1, 2·7-9·4); ratio of stroke incidence rates 0·54, 95 CI 0·43-0·68, p<0·0001. 62 versus 104 had a disabling or fatal stroke, and 37 versus 84 others had a non-disabling stroke. Combining perioperative events and strokes, net risks were 6·9 versus 10·9 at 5 years (gain 4·1, 2·0-6·2) and 13·4 versus 17·9 at 10 years (gain 4·6, 1·2-7·9). Medication was similar in both groups; throughout the study, most were on antithrombotic and antihypertensive therapy. Net benefits were significant both for those on lipid-lowering therapy and for those not, and both for men and for women up to 75 years of age at entry (although not for older patients). Interpretation Successful CEA for asymptomatic patients younger than 75 years of age reduces 10-year stroke risks. Half this reduction is in disabling or fatal strokes. Net benefit in future patients will depend on their risks from unoperated carotid lesions (which will be reduced by medication), on future surgical risks (which might differ from those in trials), and on whether life expectancy exceeds 10 years. Funding UK Medical Research Council, BUPA Foundation, Stroke Association.
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| 29. |
- Håkansson, Inge, et al.
(författare)
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Effects of sedbed properties on crop emergence. 4. Inhibitory effect of oxygen deficiency
- 2012
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 62, s. 166-171
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Tidskriftsartikel (refereegranskat)abstract
- For studies of the effects of seedbed properties on crop emergence, experiments were carried out in shallow plastic boxes. In some experiments, it was examined whether rainfall after sowing could cause oxygen deficiency in the seedbed sufficiently severe to hamper emergence. Crops studied were barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), oilseed rape (Brassica napus var. oleifera, L., Metzg.) and pea (Pisum sativum L.). For harmful oxygen deficiency to develop it appeared that rainfall would need to cause structural collapse of the surface layer followed by continuously wet weather accompanied by slow drainage and high oxygen consumption in the soil; in the experiments the latter was achieved by large amounts of easily decomposable organic matter. It was concluded that such conditions are rare in the field. Therefore, unless rainfall after sowing generates surface water for an extended period, the poor crop emergence often observed after such rainfall is nearly always caused not by oxygen deficiency, but by surface layer hardening when this layer dries.
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| 30. |
- Håkansson, Inge, et al.
(författare)
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Effects of seedbed properties on crop emergence: 1. Temporal effects of temperature and sowing depth in seedbeds with favourable properties
- 2011
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 61, s. 458-468
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Tidskriftsartikel (refereegranskat)abstract
- Rapid and uniform crop establishment is a prerequisite for efficient crop production and minimal environmental impact. Experiments were carried out in shallow plastic boxes placed directly on the ground in the field for studies of the effects of seedbed properties on emergence of various crops. This paper presents an analysis of the time required for germination and emergence under near-optimal seedbed conditions. The crops studied were barley, oats, wheat, pea, rape seed, white mustard, sugar beet, red clover and timothy. The time required for germination generally increased with size of the seeds, presumably because larger seeds needed more water to initiate germination. This applied both when comparing different crops and different seed sizes of the same crop. However, considerable differences occurred between seed lots of the same crop and there were greater differences between seed lots of the same crop than between the three small grain crops studied. Growth rate of the seedlings generally increased with seed size, presumably because of increased energy content in the seed. Consequently, the most rapid emergence was obtained from small seeds at shallow sowing and from large seeds at deep sowing. The crops studied had a minimum temperature for germination and seedling growth close to 0 degrees C. Under optimal seedbed conditions, thermal time required for 50% germination of barley was typically about 65 degrees C days over this base temperature and for seedling growth about 6 degrees C days cm(-1). From 4 cm sowing depth, about 80 degrees C days were required for emergence but with considerable variations between seed lots. For rape seed or white mustard about 40 degrees C days were required for germination and about 8 degrees C days cm(-1) for the seedling growth.
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| 31. |
- Håkansson, Inge, et al.
(författare)
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Effects of seedbed properties on crop emergence. 5. Effects of aggregate size, sowing depth and simulated rainfall after sowing on harmful surface-layer hardening
- 2012
-
Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 62, s. 362-373
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Tidskriftsartikel (refereegranskat)abstract
- Rapid, uniform crop establishment is a precondition for efficient crop production. In order to develop guidelines for seedbed preparation and sowing, extensive experiments were carried out in plastic boxes placed in the field directly on the ground for studies of the effects of seedbed properties on crop emergence. This paper deals with the effects on emergence of cereals caused by surface-layer hardening, induced by simulated rainfall (irrigation) after sowing followed by dry weather. The experimental crop was spring barley (Hordeum vulgare L.). Soils for the experiments (Eutric Cambisols, silt loam or clay loam in most cases) were collected from the surface layer of farm fields in various parts of Sweden. On soils with high silt content, irrigation after sowing often caused slumping and subsequent hardening of the whole seedbed. On clay soils, usually only a shallow surface crust formed. The earliest irrigation had the most negative effects on crop emergence. On a silt loam soil with unstable structure, irrigation with only 5 mm reduced emergence to under 20%. Later or heavier irrigation was often less negative, as it allowed the plants to emerge before the surface layer dried and hardened. Deep sowing greatly increased the negative effects on emergence, whereas soil aggregate size usually had negligible effects. It was concluded that when sowing in practice, seedbed preparation and sowing depth should be chosen to promote the fastest possible emergence. Sowing immediately before rain should be avoided, as should shallow sowing that requires rain for the seed to germinate.
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| 32. |
- Håkansson, Inge, et al.
(författare)
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Effects of seedbed properties on crop emergence. 6. Requirements of crops with small seeds
- 2013
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Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 63, s. 554-563
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Tidskriftsartikel (refereegranskat)abstract
- The effects of seedbed properties on emergence of various crops were studied in a series of experiments. Results for crops with seeds weighing <7 mg are reported here. The experiments were carried out in shallow plastic boxes placed directly on the ground in the field. Small seeds require shallow sowing, which is a great disadvantage in the event of dry weather after sowing, particularly on clay and clay loam soils, where the upper 3-cm soil layer quickly dries to wilting point. Nevertheless, good emergence of crops with seeds weighing 2-7 mg (white mustard, Sinapis alba L., oilseed rape, Brassica rapa L., Metzg., sugar beet, Beta vulgaris L. and red clover, Trifolium pratense L.) was often obtained when the seed was placed at about 3-cm depth directly on a firm basal layer with >6% plant-available water and covered by soil dominated by aggregates <5 mm. Cruciferous crops germinated most rapidly, which facilitated emergence from shallow depth. Sowing could be slightly shallower in coarse-textured than in fine-textured soils, since the former soils dry less rapidly to below wilting point. For timothy (Phleum pratense L.) with seeds weighing about 0.5 mg and requiring a sowing depth <2.5 cm, it was impossible to design a seedbed that eliminated the risk of poor emergence in dry weather. Firming of the seedbed after sowing favoured emergence only in initially dry seedbeds. The risk of poor emergence because of surface layer hardening was minimised by placing seeds at a depth and in seedbed conditions that promoted the fastest possible emergence.
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| 33. |
- Ivarsson, Tord, 1946, et al.
(författare)
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The Youth Self-Report (YSR) and the Depression Self-Rating Scale (DSRS) as measures of depression and suicidality among adolescents.
- 2002
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Ingår i: European Child and Adolescent Psychiatry. - 1018-8827. ; 11:1, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- Two hundred and thirty-seven adolescents from a junior high school in a small community outside Goteborg, Sweden, completed the Youth Self Report (YSR) and the Depression Self Rating Scale (DSRS). Self-reported suicidality and biographical data were also recorded. The school doctor and nurse assessed the adolescents' somatic, psychological and behavioural problems using school health-records. The convergent validity of the YSR total problems scale and syndrome scales were tested against the DSRS. Discriminant validity was assessed by the two measures' ability to predict suicidality and school health problems. The Internalising (r = 0.65**) and Anxious/Depressed (r= 0.61**) syndrome scales of the YSR had the highest correlations with the DSRS. However, all YSR syndrome scales were significantly, though more modestly, correlated with the DSRS. Using stepwise logistic regression analysis, four YSR sub-scales [Social Withdrawal, Anxious/Depressed, Attention problems and Delinquency] predicted mild-severe self-reported depression (DSRS scores 12 and above). The YSR syndrome scales Anxious/Depressed and Delinquency predicted suicide ideation whereas the Self-destructive/Identity problem and Social Withdrawal (low scores) scales predicted Suicide attempts. The YSR Anxious/Depressed sub-scale and the DSRS total score seem to measure a similar dimension. However, the Anxious/Depressed and Selfdestructive/Identity problem scales were superior in predicting suicidality.
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| 34. |
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| 35. |
- Johannesson, Pär, 1969, et al.
(författare)
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A Robustness Approach to Reliability
- 2013
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Ingår i: Quality and Reliability Engineering International. - : Wiley. - 1099-1638 .- 0748-8017. ; 29:1, s. 17-32
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Forskningsöversikt (refereegranskat)abstract
- Reliability of products is here regarded with respect to failure avoidance rather than probability of failure. To avoid failures,we emphasize variation and suggest some powerful tools for handling failures due to variation. Thus, instead of technicalcalculation of probabilities from data that usually are too weak for correct results, we emphasize the statistical thinking thatputs the designers focus on the critical product functions.Making the design insensitive to unavoidable variation is called robust design and is handled by (i) identification andclassification of variation, (ii) design of experiments to find robust solutions, and (iii) statistically based estimations of propersafety margins.Extensions of the classical failure mode and effect analysis (FMEA) are presented. The first extension consists of identifyingfailure modes caused by variation in the traditional bottom–up FMEA analysis. The second variation mode and effect analysis(VMEA) is a top–down analysis, taking the product characteristics as a starting point and analyzing how sensitive thesecharacteristics are to variation.In cases when there is sufficient detailed information of potential failure causes, the VMEA can be applied in its mostadvanced mode, the probabilistic VMEA. Variation is then measured as statistical standard deviations, and sensitivities aremeasured as partial derivatives. This method gives the opportunity to dimension tolerances and safety margins to avoidfailures caused by both unavoidable variation and lack of knowledge regarding failure processes.
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| 36. |
- Kainiemi, Veera, et al.
(författare)
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Effects of autumn tillage and residue management on soil respiration in a long-term field experiment in Sweden
- 2015
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Ingår i: Journal of Plant Nutrition and Soil Science. - : Wiley. - 1436-8730 .- 1522-2624. ; 178, s. 189-198
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Tidskriftsartikel (refereegranskat)abstract
- Several previous field studies in temperate regions have shown decreased soil respiration after conventional tillage compared with reduced or no-tillage treatments. Whether this decrease is due to differences in plant residue distribution or changes in soil structure following tillage remains an open question. This study investigated (1) the effects of residue management and incorporation depth on soil respiration and (2) biological activity in different post-tillage aggregates representing the actual size and distribution of aggregates observed in the tilled layer. The study was conducted within a long-term tillage experiment on a clay soil (Eutric Cambisol) in Uppsala, Sweden. After 38 y, four replicate plots in two long-term treatments (moldboard plowing (MP) and shallow tillage (ST)) were split into three subplots. These were then used for a short-term trial in which crop residues were either removed, left on the surface or incorporated to about 6 cm depth (ST) or at 20 cm depth (MP). Soil respiration, soil temperature, and water content were monitored during a 10-d period after tillage treatment. Respiration from aggregates of different sizes produced by ST and MP was also measured at constant water potential and temperature in the laboratory. The results showed that MP decreased short-term soil respiration compared with ST or no tillage. Small aggregates (< 16 mm) were biologically most active, irrespective of tillage method, but due to their low proportion of total soil mass they contributed < 1.5% to total respiration from the tilled layer. Differences in respiration between tillage treatments were found to be attributable to indirect effects on soil moisture and temperature profiles and the depth distribution of crop residues, rather than to physical disturbance of the soil.
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| 37. |
- Kainiemi, Veera, et al.
(författare)
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Short-term organic matter mineralisation following different types of tillage on a Swedish clay soil
- 2013
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Ingår i: Biology and Fertility of Soils. - : Springer Science and Business Media LLC. - 0178-2762 .- 1432-0789. ; 49, s. 495-504
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Tidskriftsartikel (refereegranskat)abstract
- Reduced tillage is proposed as a method of C sequestration in agricultural soils. However, tillage effects on organic matter turnover are often contradictory and data are lacking on how tillage practices affect soil respiration in northern Europe. This field study (1) quantified the short-term effects of different tillage methods and timing on soil respiration and N mineralisation and (2) examined changes in aggregate size distribution due to different tillage operations and how these relate to soil respiration. The study was conducted on Swedish clay soil (Eutric Cambisol) and compared no-tillage with three forms of tillage applied in early or late autumn 2010: mouldboard ploughing to 20-22 cm and chisel ploughing to 12 or 5 cm depth. Soil respiration, soil temperature, gravimetric water content, mineral N and aggregate size distribution were measured. The results showed that respiration was significantly higher (P < 0.001) in no-till than in tilled plots during the 2 weeks following tillage in early September. Later tillage gave a similar trend but treatments did not differ significantly. Soil tillage and temperature explained 56 % of the variation in respiration. In the early tillage treatment, soil respiration decreased with tillage depth. Mineral N status was not affected by tillage treatment or timing. Soil water content did not differ significantly between tillage practices and therefore did not explain differences in respiration. The results indicate that conventional tillage in early autumn may reduce short-term soil respiration compared with chisel ploughing and no-till in clay soils in northern Europe.
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| 38. |
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| 39. |
- Keller, Thomas, et al.
(författare)
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A model for prediction of vertical stress distribution near the soil surface below rubber-tracked undercarriage systems fitted on agricultural vehicles
- 2016
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Ingår i: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 155, s. 116-123
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Tidskriftsartikel (refereegranskat)abstract
- Rubber-tracked vehicles are becoming increasingly popular in agriculture. Rubber-tracked undercarriage systems are typically fitted instead of tyres on heavy agricultural vehicles, with the aim of e.g. decreasing soil stress and soil compaction risks. Therefore, accurate prediction of soil stresses below rubber-tracked systems is important. Here, we present a model for prediction of vertical stress distribution at the rubber track soil interface. In the model, the rubber-tracked undercarriage system consists of a front and rear wheel (idler and drive wheel) and a number of support rollers. The stress distribution in the longitudinal direction under a wheel or roller is described by harmonic oscillation, with the dynamic contact length being a function of wheel or roller diameter. In the lateral direction, the stress distribution is modelled by a linear function, with the maximum stress under the centre line of the track. Model input parameters include the load on the track, track width, track length (distance between front and rear axles), number of support rollers and wheel and roller diameter. The model, which is written in Visual Basic and implemented as a macro in an Excel spreadsheet, then computes the vertical stress at the rubber track soil interface based on these inputs and the stress distribution generated in the contact area can be used to simulate soil stresses. The model provides realistic estimates of the vertical stress at the contact between rubber track and soil, thereby improving predictions of soil stress and the compaction risks of rubber-tracked agricultural vehicles. (C) 2015 Elsevier B.V. All rights reserved.
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| 40. |
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| 41. |
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| 42. |
- Keller, Thomas, et al.
(författare)
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Driver-Pressure-State-Impact-Response (DPSIR) Analysis and Risk Assessment for Soil Compaction-A European Perspective
- 2015
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Ingår i: Advances in Agronomy. - : Elsevier. - 0065-2113 .- 2213-6789. ; 133, s. 183-237
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Forskningsöversikt (refereegranskat)abstract
- Compaction of subsoil is a hidden but persistent damage that impairs a range of soil functions and ecosystem services. We analyzed the soil compaction issue in the Driver-Pressure-State-Impact-Response (DPSIR) context. The driving force (DPSIR-D) is the farmers' efforts to sustain economic viability. This entails a steady increase in the size and weight of the agricultural machinery (DPSIR-P) exerting the specific pressures on the soil system. Simulations using historical data for agricultural machinery show significant increases in the mechanical stresses exerted on the soil profile during the last five decades. Surveys and comparative measurements (DPSIR-S) in the literature indicate that much of the European subsoil is compacted to critical levels for cropping. This calls for changes in agricultural management (DPSIR-R). Mechanical stresses impact the soil (DPSIR-I) by reducing the volume, dimensions, and interconnections of soil pores. Subsequent impacts on ecosystem services (subtle DPSIR-I aspects) include a decrease in crop production, an impaired soil filtering of pollutants, and the risk of higher greenhouse gas emissions. The natural ability of compacted subsoil to recover is poor. We highlight the need to expand the DPSIR concept to include a risk assessment methodology to identify sustainable management systems. Risk assessment involves the evaluation of the mechanistic cause-effect chain of the compaction process. Measured data as well as modeling indicate that contemporary tires are not able to carry the loads frequently inflicted on wet soil without exerting critical stresses on deep subsoil layers. We suggest the use of online modeling tools that combine existing knowledge. Such tools may also create maps of vulnerable areas from the field to the continent scale. Groups of stakeholders including researchers, farmers and their consultants, and policy-makers need to identify sustainable traffic systems that secure both presently focused ecosystem services as well as nonuse soil values (the bequest for future generations).
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| 43. |
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| 44. |
- Keller, Thomas, et al.
(författare)
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In Situ Subsoil Stress-Strain Behavior in Relation to Soil Precompression Stress
- 2012
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Ingår i: Soil Science. - 0038-075X .- 1538-9243. ; 177, s. 490-497
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Tidskriftsartikel (refereegranskat)abstract
- Soil compaction negatively influences many important soil functions, including crop growth. Compaction occurs when the applied stress, sigma, overcomes the soil strength. Soil strength in relation to compaction is typically expressed by the soil precompression stress, sigma(pc). Deformation is assumed to be elastic and reversible as long as sigma <= sigma(pc). This work examined soil stress-strain behavior as measured in situ during wheeling experiments and related it to the stress-strain behavior and sigma(pc) measured on soil cores in uniaxial compression tests in the laboratory. The data analyzed were from a large number of wheeling experiments carried out in Sweden and Denmark on soils with a wide range of texture. Contradicting the concept of precompression stress, we observed residual strain, epsilon(res), at sigma <= sigma(pc). These observations were supported by stress-strain data measured in uniaxial compression tests, which likewise showed epsilon(res) > 0 at sigma <= sigma(pc). Residual strain was observed in the field when sigma exceeded approximately 40 kPa, and when the ratio sigma/sigma(pc) exceeded roughly 0.1, although epsilon(res) was very small at sigma/sigma(pc) < 0.5. These values were similar to those obtained on confined uniaxial compression curves. On the basis of our findings, we question the use of sigma(pc) as a measure of soil strength and call for a reevaluation of the precompression stress concept.
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| 45. |
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| 46. |
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| 47. |
- Keller, Thomas, et al.
(författare)
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Persistent effects of subsoil compaction on pore size distribution and gas transport in a loamy soil
- 2012
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Ingår i: Soil and Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 122, s. 42-51
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Tidskriftsartikel (refereegranskat)abstract
- The ever-increasing weight of agricultural machines exacerbates the risk of subsoil compaction, a condition believed to be persistent and difficult to alleviate by soil tillage and natural loosening processes. However, experimental data on the persistency of subsoil compaction effects on soil pore functioning are scarce. This study evaluated and quantified persistent effects of subsoil compaction on soil pore structure and gas transport processes using intact cores taken at 0.3, 0.5, 0.7 and 0.9 m depth from a loamy soil in a compaction experiment in southern Sweden (Brahmehem Farm). The treatments included four repeated wheelings with similar to 10 Mg wheel loads. Water retention characteristics (WRC), air permeability (k(a)) and gas diffusivity (D-s/D-o) were measured. A dual-porosity model fitted the WRC well, and there was a reduction in the volume of macropores >30 mu m in compacted compared with control soil for all soil depths. Averaged for all sampling depths and also for some individual depths, both k(a) and D-s/D-o were significantly reduced by compaction. Gas transport measurements showed that the experimental soil was poorly aerated, with local anoxic conditions at water regimes around field capacity in all plots and depths, but with significantly higher percentage anoxia in compacted soil. Our main findings were that: (1) commonly used agricultural machinery can compact the soil to 0.9 m depth, (2) the effect may persist for at least 14 years, and (3) important soil functions are affected. (c) 2012 Elsevier B.V. All rights reserved.
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| 48. |
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| 49. |
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| 50. |
- Keller, Thomas, et al.
(författare)
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SoilFlex-LLWR: linking a soil compaction model with the least limiting water range concept
- 2015
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Ingår i: Soil Use and Management. - : Wiley. - 0266-0032 .- 1475-2743. ; 31, s. 321-329
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Tidskriftsartikel (refereegranskat)abstract
- Soil compaction impacts growing conditions for plants: it increases the mechanical resistance to root growth and modifies the soil pore system and consequently the supply of water and oxygen to the roots. The least limiting water range (LLWR) defines a range of soil water contents within which root growth is minimally limited with regard to water supply, aeration and penetration resistance. The LLWR is a function of soil bulk density (BD), and hence directly affected by soil compaction. In this paper, we present a new model, SoilFlex-LLWR', which combines a soil compaction model with the LLWR concept. We simulated the changes in LLWR due to wheeling with a self-propelled forage harvester on a Swiss clay loam soil (Gleyic Cambisol) using the new SoilFlex-LLWR model, and compared measurements of the LLWR components as a function of BD with model estimations. SoilFlex-LLWR allows for predictions of changes in LLWR due to compaction caused by agricultural field traffic and therefore provides a quantitative link between impact of soil loading and soil physical conditions for root growth.
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