| 1. |
- Carlsson, Per, 1951-, et al.
(författare)
-
National Model for Transparent Vertical Prioritisation in Swedish Health Care
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The proposed national model described in this report has been developed by a working group comprised of staff from the National Board of Health and Welfare, the National Centre for Priority Setting in Health Care, and other organisations involved in vertical prioritisation – including the Östergötland County Council, Stockholm County Council, Västra Götaland, the Health Services Region of Southern Sweden, the Swedish Society of Medicine, the Swedish Society of Nursing, and the Swedish Association of Health Professionals. Throughout the process of designing the model, the Swedish Federation of Occupational Therapists and the Swedish Association of Registered Physiotherapists were regularly informed and given opportunities to review and comment on the proposal. Furthermore, the report was reviewed and discussed at a meeting with invited representatives from the other county councils, the Pharmaceutical Benefits Board, and several professional interest groups. Viewpoints were also obtained at a seminar arranged by PrioNet, a network of individuals interested in prioritisation.Potentially, the working model described in Chapter 4 could be used in any context where vertical prioritisation takes place, e.g. activities arranged by the state, county councils, municipalities, hospital departments, and professional groups.This report is designed to be a useful tool for those working on development projects in priority setting. We believe that the contents must be adapted, with the help of relevant examples and some simplifications; to fit the specific needs of different projects or groups. The text must also be adapted to a target group’s knowledge and previous experience in dealing with transparent priority setting. It must be the responsibility of each provider and other affected organisation to adapt the material to the given situation and project. The National Centre for Priority Setting in Health Care, the National Board of Health and Welfare, and others who have participated actively in this effort can be helpful to various target groups in adapting this report.When and how to engage in practically implementing vertical prioritisation are questions that need to be answered at the local level. Primarily, it is the duty of the local authorities/providers to take responsibility for implementation. Professional organisations also play an important role. Public agencies, universities, and knowledge centres should be sources of support for the local authorities/providers.The Riksdag’s resolution on prioritisation served as the foundation for developing the model.Where there are areas of uncertainty in how to translate these guidelines in practice, or where practical implementation might conflict with the principles, we have pointed this out.Our conclusions and proposals are the following:When facing a choice – regardless of whether it involves allocating new resources for different purposes, or to implement cutbacks – it can be advantageous to rank the possible choices in order of priority. In our model, only the relevant options can be ranked by priority. The consequences of this ranking are not obvious at the outset, but can serve as a basis either to allocate more resources or ration by some means.In vertical prioritisation, it is advantageous to organise the prioritization process starting from a general categorisation of health problems/disease groups. As a rule, these categories cover many organisational units/clinical departments, specialties, or professional groups, thus providing a more multidimensional view of the problem. Furthermore, this allows the process to start from a patient/population perspective, which appears to be more goal-oriented than an organisational/staff perspective.That which is ranked, i.e. one of the choices, we refer to as a prioritization object. We suggest that prioritisation objects consist of different combinations of health conditions and interventions.1 When deciding on the appropriate level of detail, the decision must be based on the context in which prioritisation is carried out. A starting point would be to focus on typical cases, large-volumes services, and controversial care.All forms of vertical prioritisation should be based on the ethical principles that the Riksdag decided should apply in prioritising health services. However, these ethical principles must be made known, clarified, and perhaps complemented before they can be applied to practical priority setting. Furthermore, we believe that the Riksdag’s four so-called priority groups should not be part of the model.The human dignity principle, i.e. that all people should have equal value and equal rights to care irrespective of their personal characteristics and function in society, is the undisputed cornerstone in priority setting. When personal characteristics such as age, gender, lifestyle, or function of a group are expressions of the presence of special needs, so that benefits of the interventions are different, these personal characteristics could be addressed in a priority at the group level. Further discussion is needed regarding the question of how external effects (i.e. the effects of an intervention on families and groups other than the individual directly affected by the intervention) should be valued in priority setting.The concept of need in health care includes both the severity level of the condition and the expected benefits of intervention. As a patient, one needs only those interventions that can be expected to yield benefits. Based on this definition of need, a person does not need an intervention that does not improve health and quality of life, i.e. an intervention with no benefit. In such cases, health services have a responsibility to refer people who seek care for some type of problem, to other appropriate services.The Riksdag’s guidelines regarding the cost-effectiveness principle (applied to individual patients) are too limited to provide guidance for vertical prioritisation at the group level. From the outset, the Government’s bill (Priority Setting in Health Care) highlighted the importance of differentiating a cost-effectiveness principle that applied to choices among various interventions for the individual patient (where the principle can be applied as the Commission of Inquiry proposed) and the aim of health services to achieve high cost-effectiveness in health care generally. Here we also refer to the Riksdag’s directive to the Pharmaceutical Benefits Board. In its decisions on subsidising (prioritising) a drug, the Board should determine, e.g. whether the drug is cost effective from a societal perspective, which requires comparing the patient benefits of the drug to its cost. In such decisions, the cost effectiveness should be considered along with the needs and solidarity principle and the human dignity principle.The proposed working model essentially concurs with the working model used by the National Board of Health and Welfare in developing national guidelines. In describing a national working model, it is not possible to include every aspect that might be considered. Hence, one must start from the model and decide which other relevant aspects should be included. For instance, the International Classification on Functioning, Disability, and Health (ICF) can be used as guidance to describe the severity of health conditions.Due to the wealth of variety in outcome measures for different activities, and the limited experience in working with explicit threshold values, we believe would be premature to recommend standardised categories, e.g. risk levels. However, it is important that those working with prioritization describe their reasoning. Primarily, the categories applied by the Swedish Council on Technology Assessment in Health Care (SBU) to grade the scientific evidence of an intervention’s effects should be used. Local prioritisation projects with limited resources at their disposal should describe (text) their appraisal of the scientific evidence and reference the scientific sources used. The strength of evidence should be expressed in numbers only when supporting a conclusion of a systematic review by SBU, or other literature reviews of good quality.Prioritisation projects having access to health economic evaluation should, until further notice, adhere to the approach used by the National Board of Health and Welfare and present cost-effectiveness on a scale from low to very high cost per life-year gained or cost per quality-adjusted life-year. Economic evidence should be presented according to the principles applied by the National Board of Health and Welfare. In local projects with limited resources, or problems in consistently acquiring information on cost effectiveness, we recommend that the authors at least discuss cost effectiveness in cases where the priority ranking would be decisively affected when costs are weighed in.A 10-level ranking list should be used. The ranking list should be complemented by a “don’t do” list for methods that should not be used at all, or not used routinely, and a research and development (R&D) list for methods where the evidence still insufficient to motivate their use in standard practice. In the absence of an objective quantitative/mathematical method, a qualitative method should be used in the appraisal. Here too, we believe that it is not yet possible to establish standard criteria to determine within which ranking level a prioritisation object should fall.Results should be presented as a ranking list. The parameters used as a basis for prioritisation should also be presented in a uniform manner in ranking lists that are shared with other parties. For pedagogic reasons, details concerning language and format need to be adapted to the respective target groups.Thresholds for what constitutes an acceptable coverage of need (care quality, volume, and percentage of the patient group with access to services) a
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| 2. |
- Carlsson, Per, 1951-, et al.
(författare)
-
Nationell modell för öppna vertikala prioriteringar inom svensk hälso- och sjukvård
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En arbetsgrupp med personer från Socialstyrelsen och PrioriteringsCentrum, andra organisationer som arbetat med vertikala prioriteringar såsom Landstinget i Östergötland, Stockholms läns landsting, Västra Götaland, Södra sjukvårdsregionen, Svenska Läkaresällskapet, Svensk sjuksköterskeförening och Vårdförbundet har tagit fram detta förslag. Förslaget har fortlöpande förankrats hos Förbundet Sveriges Arbetsterapeuter och Legitimerade Sjukgymnasters Riksförbund som kunnat lämna synpunkter på utformningen av odellen.Dessutom har rapporten varit föremål för granskning och diskussion vid ett möte med inbjudna representanter från övriga landsting, Läkemedelsförmånsnämnden och flera yrkesorganisationer. Synpunkter har också inkommit från ett seminarium som arrangerades av PrioNet, ett nätverk av personer med intresse för prioriteringar.Den arbetsmodell som beskrivs i kapitel 4 ska kunna användas i alla sammanhang där vertikala prioriteringar sker såsom aktiviteter som arrangeras av staten, landsting, kommuner, kliniker, professionella grupper eller motsvarande.Rapporten är skriven på ett sådant sätt att den ska kunna användas i första hand som ett stöd till dem som bedriver utvecklingsarbete rörande prioriteringar. Vi tror att innehållet måste anpassas till olika verksamheter eller personalgruppers specifika behov med hjälp av kompletterande exempel och vissa förenklingar. Texten måste givetvis också anpassas till de kunskaper och tidigare erfarenheter som den aktuella målgruppen har när det gäller arbete med öppna prioriteringar. Sådana situations- och verksamhetsanpassade versioner måste det åligga varje sjukvårdshuvudman och andra berörda organisationer att utarbeta. PrioriteringsCentrum, Socialstyrelsen och andra parter som deltagit aktivt i detta arbete kan givetvis vara behjälpliga i arbetet med att bearbeta denna rapport för olika målgrupper.Frågan om när och hur arbetet med vertikala prioriteringar ska bedrivas i praktiken kan också endast besvaras lokalt. Det är i första hand ett nsvar för huvudmännen att ta ansvar för implementeringen. Professionella organisationer har också en viktig roll. Myndigheter, universitet och kunskapscentra ska vara ett stöd till huvudmännen.Utgångspunkten i modellutvecklingen är Riksdagens beslut om prioriteringar. När det finns oklarheter om hur dessa riktlinjer ska omsättas i praktiken eller att praktiken kan förefalla i konflikt med principerna har vi påpekat detta.När man står inför ett val - oavsett om det handlar om att fördela nya resurser till olika ändamål eller att genomföra besparingar - kan det vara en fördel att kunna rangordna tänkbara valmöjligheter i enprioriteringsordning. I vår modell innebär prioritering enbart att de relevanta alternativen rangordnas. Konsekvenserna av denna rangordning är inte på förhand given utan kan ligga till grund såväl för tillskott av resurser som för ransonering av något slag.Vid en vertikal prioritering är det en fördel att organisera prioriteringsarbetet så att det utgår från en grov uppdelning i hälsoproblem/sjukdomsgrupper. En sådan uppdelning innebär i regel att flera organisationsenheter/kliniker, specialiteter eller yrkesgrupper berörs och man får en mer allsidig belysning av problemet. Dessutom utgår man från ett patient/befolkningsperspektiv vilket förefaller mer ändamålsenligt än ett organisatoriskt/personalperspektiv.Det som rangordnas och som någon väljer mellan benämner vi prioriteringsobjekt. Vi föreslår att prioriteringsobjektet utgörs av olika kombinationer av hälsotillstånd och åtgärder1. När det gäller att bestämma en lämplig detaljeringsgrad måste det avgöras utifrån sammanhanget prioriteringar ska göras i. En utgångspunkt är att fokusera på typfall, vård som representerar stor volym och kontroversiell vård.Alla former av vertikala prioriteringar ska baseras på de etiska principer som riksdagen beslutat ska gälla vid prioriteringar inom hälso- och sjukvården. De etiska principerna behöver dock göras kända, förtydligas och eventuellt kompletteras för att kunna omsättas i praktiska prioriteringar. Vidare anser vi att riksdagens fyra så kallade prioriteringsgrupper inte ska ingå i modellen.Människovärdesprincipen, som innebär att alla människor bör ha lika värde och samma rätt till vård oberoende av personliga egenskaper och funktioner i samhället, är den självklara utgångspunkten vid prioriteringar. När personliga egenskaper såsom ålder, kön, livsstil eller funktion hos en grupp är ett uttryck för att speciella behov föreligger så att nytta med insatserna blir olika ska de personliga egenskaperna kunna beaktas i en prioritering på gruppnivå. Frågan om hur externa effekter, d v s effekten av en insats för närstående och andra grupper än den individ som är direkt berörd av insatsen, ska värderas vid en prioritering behöver diskuteras ytterligare.Med behov av hälso- och sjukvård menas både tillståndets svårighetsgrad och den förväntade nyttan av en åtgärd. Som patient har man endast behov av sådana vårdåtgärder som man förväntas ha nytta av. Motsatt gäller att en människa enligt detta sätt att definiera behov inte behöver åtgärder som inte förbättrar hälsan och livskvaliteten, sådana som hon inte har nytta av. Här har givetvis hälso- och sjukvården ett ansvar att lotsa människor de kommer i kontakt med, och som far illa på något sätt, till andra lämpliga aktörer.Riksdagens riktlinjer, när det gäller kostnadseffektivitetsprincipen (tillämpad för enskilda patienter), är för begränsad för att vägleda vid vertikala prioriteringar som gäller prioritering på gruppnivå. Regeringen konstaterade redan i prioriteringspropositionen att det är angeläget att skilja på en kostnadseffektivitetsprincip som gäller val mellan olika åtgärder för den enskilde patienten (där principen kan tillämpas som utredningen föreslår) och på hälso- och sjukvårdens strävan efter en hög kostnadseffektivitet när det gäller vårdens verksamhet i allmänhet. Här stödjer vi oss på Riksdagens direktiv till Läkemedelsförmånsnämnden. Nämnden ska vid beslut om subvention (prioriteringar) av ett läkemedel bl a bedöma om det är kostnadseffektivt i ett samhälleligt perspektiv, vilket innebär att man ställer patientnyttan av läkemedlet mot kostnaden. I bedömningen ska kostnadseffektiviteten vägas samman med behovs- och solidaritetsprincipen och människovärdesprincipen.Den föreslagna arbetsmodellen överensstämmer i allt väsentligt med den arbetsmodell som används av Socialstyrelsens vid framtagning av nationella riktlinjer. Det är inte möjligt att rymma alla aspekter som kan vara aktuella att beakta vid beskrivning av en nationell arbetsmodell. Man måste därför utgå från modellen och fundera på vilka andra relevanta aspekter som dessutom bör vägas in. T ex kan den internationella klassifikationen för funktionsförmåga (ICF) användas som vägledning.På grund av den stora variationsrikedomen av effektmått i olika verksamheter och de begränsade erfarenheter som finns att arbeta med sådana explicita gränsvärden anser vi att det är för tidigt att rekommendera en enhetlig indelning i t ex risknivåer. Det är dock viktigt att de som arbetar med prioriteringar redovisar hur de har resonerat.SBU:s klassifikation för att gradera den vetenskapliga evidensen för en åtgärds effekt bör användas i första hand. Lokala prioriteringsprojekt med begränsade resurser till sitt förfogande föreslås redovisa bedömningen av det vetenskapliga underlaget med ord och referera till det kunskapsunderlag som använts. Evidensstyrkan bör endast uttryckas med siffror då man stöder en slutsats på en systematisk kunskapsöversikt från SBU eller en annan översikt av god kvalitet.Prioriteringsarbeten där hälsoekonomiska data finns tillgängliga bör tills vidare ansluta till Socialstyrelsens arbetssätt och ange kostnadseffektivitet i en skala från låg till mycket hög kostnad per vunnet levnadsår eller kostnad per kvalitetsjusterat levnadsår. Den hälsoekonomiska evidensen bör redovisas i enlighet med de principer som Socialstyrelsen tillämpar. I lokala projekt med små resurser eller svårigheter att konsekvent få fram uppgifter om kostnadseffektivitet rekommenderar vi att man åtminstone resonerar om kostnadseffektivitet i de fall prioriteringsordningen på ett avgörande sätt påverkas när kostnaderna vägs in.Tio nivåer bör användas för rangordning samt att rangordningslistan kompletteras med en ”icke-göra-lista” för metoder som inte bör utföras alls eller rutinmässigt samt en FoU-lista för metoder där det fortfarande saknas tillräcklig evidens för att kunna motivera ett införande i rutinsjukvården. Sammanvägningen sker företrädesvis med en kvalitativ metod i avsaknad av en invändningsfri kvantitativ/matematisk metod. Likaså tror vi att det för närvarade inte är möjligt att fastställa entydiga kriterier som avgör inom vilken rangordningsnivå ett prioriteringsobjekt ska hamna.Resultatet bör presenteras i form av en rangordningslista. De parametrar som ligger till grund för prioriteringen bör också på ett enhetligt sätt redovisas i sådana rangordningslistor som visas för andra. I detalj kan språket och utseendet av pedagogiska skäl behöva anpassas för respektive målgrupp.Gränser för vad som är acceptabel behovstäckning (vårdkvalitet, mängd liksom andel av de i patientgrupp som får tillgång till insatsen) är en regional och lokal fråga och ingår därför inte i den nationella modellen.
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| 3. |
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| 4. |
- Mårtensson, Ulrika, et al.
(författare)
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Deletion of the G protein-coupled receptor 30 impairs glucose tolerance, reduces bone growth, increases blood pressure, and eliminates estradiol-stimulated insulin release in female mice.
- 2009
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Ingår i: Endocrinology. - : The Endocrine Society. - 1945-7170 .- 0013-7227. ; 150:2, s. 687-98
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Tidskriftsartikel (refereegranskat)abstract
- In vitro studies suggest that the G protein-coupled receptor (GPR) 30 is a functional estrogen receptor. However, the physiological role of GPR30 in vivo is unknown, and it remains to be determined whether GPR30 is an estrogen receptor also in vivo. To this end, we studied the effects of disrupting the GPR30 gene in female and male mice. Female GPR30((-/-)) mice had hyperglycemia and impaired glucose tolerance, reduced body growth, increased blood pressure, and reduced serum IGF-I levels. The reduced growth correlated with a proportional decrease in skeletal development. The elevated blood pressure was associated with an increased vascular resistance manifested as an increased media to lumen ratio of the resistance arteries. The hyperglycemia and impaired glucose tolerance in vivo were associated with decreased insulin expression and release in vivo and in vitro in isolated pancreatic islets. GPR30 is expressed in islets, and GPR30 deletion abolished estradiol-stimulated insulin release both in vivo in ovariectomized adult mice and in vitro in isolated islets. Our findings show that GPR30 is important for several metabolic functions in female mice, including estradiol-stimulated insulin release.
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| 5. |
- Alerstam, Thomas, et al.
(författare)
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Flight speeds among bird species : allometric and phylogenetic effects.
- 2007
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 5:8, s. e197-
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Tidskriftsartikel (refereegranskat)abstract
- Flight speed is expected to increase with mass and wing loading among flying animals and aircraft for fundamental aerodynamic reasons. Assuming geometrical and dynamical similarity, cruising flight speed is predicted to vary as (body mass)(1/6) and (wing loading)(1/2) among bird species. To test these scaling rules and the general importance of mass and wing loading for bird flight speeds, we used tracking radar to measure flapping flight speeds of individuals or flocks of migrating birds visually identified to species as well as their altitude and winds at the altitudes where the birds were flying. Equivalent airspeeds (airspeeds corrected to sea level air density, Ue) of 138 species, ranging 0.01-10 kg in mass, were analysed in relation to biometry and phylogeny. Scaling exponents in relation to mass and wing loading were significantly smaller than predicted (about 0.12 and 0.32, respectively, with similar results for analyses based on species and independent phylogenetic contrasts). These low scaling exponents may be the result of evolutionary restrictions on bird flight-speed range, counteracting too slow flight speeds among species with low wing loading and too fast speeds among species with high wing loading. This compression of speed range is partly attained through geometric differences, with aspect ratio showing a positive relationship with body mass and wing loading, but additional factors are required to fully explain the small scaling exponent of Ue in relation to wing loading. Furthermore, mass and wing loading accounted for only a limited proportion of the variation in Ue. Phylogeny was a powerful factor, in combination with wing loading, to account for the variation in Ue. These results demonstrate that functional flight adaptations and constraints associated with different evolutionary lineages have an important influence on cruising flapping flight speed that goes beyond the general aerodynamic scaling effects of mass and wing loading.
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| 6. |
- Anderberg, Cecilia, et al.
(författare)
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Wear Resistance of Smooth Automotive Cylinder Liner Surfaces
- 2005
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Ingår i: World Tribology Congress III, Volume 2. - New York, NY : ASME Press. - 0791842029 ; , s. 603-604
-
Konferensbidrag (refereegranskat)abstract
- Demands for decreased environmental impact from vehicles are resulting in a strong push for decreased engine oil, fuel consumption and weight. New machining and coating technologies have offered ways to attack these problems. Engine oil and fuel consumption are to a great extent controlled by the topography of the cylinder liner surface and it is therefore important to optimise this surface. Recent engine tests have shown a reduction in oil consumption when using cylinder liners with a smoother finish than that given by the current plateau honing. However, engine manufacturers are hesitant to introduce smoother liner surfaces because of fears of severe wear and scuffing. There is also the possibility that smoother liner surfaces may be more sensitive to the choice of piston ring finishes. This paper therefore seeks to investigate the functional performance and resistance to wear of these smooth cylinder liners and the mating top ring surfaces. Copyright © 2005 by ASME
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| 7. |
- Axelsson Rosén, Stina, et al.
(författare)
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In vitro effects of antipsychotics on human platelet adhesion and aggregation and plasma coagulation
- 2007
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Ingår i: Clinical and experimental pharmacology & physiology. - : Wiley. - 0305-1870 .- 1440-1681. ; 34:8, s. 775-780
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Tidskriftsartikel (refereegranskat)abstract
- 1. Several studies suggest an association between venous thromboembolism and the use of antipsychotic drugs, especially clozapine, but the biological mechanisms are unknown. It has been suggested that antipsychotic drugs enhance aggregation of platelets and thereby increase the risk of venous thrombosis. The purpose of the present study was to examine the effects of clozapine and its main metabolite, N-desmethyl clozapine, as well as olanzapine, risperidone and haloperidol, on platelet adhesion and aggregation and on plasma coagulation in vitro. 2. Blood was collected from healthy subjects free of medication. Platelet adhesion to different protein surfaces and aggregation were measured in microplates. The coagulation methods of activated partial thromboplastin time (APTT) and prothrombin time were performed in platelet-poor plasma. 3. Clozapine was the only compound that increased platelet adhesion and aggregation and shortened APTT. The effect appeared at therapeutic concentrations and was significant but weak. 4. This weak effect of clozapine on haemostasis may explain, in part, the association of this compound and venous thromboembolism. © 2007 The Authors.
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| 8. |
- Berglund, Johan C, 1978, et al.
(författare)
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Measuring strategies for smooth tool steel surfaces
- 2008
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Ingår i: Proceedings. - Aachen : Shaker Verlag. - 1610-4773. - 9783832269128 - 3832269126 ; , s. 110-119
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Comparisons between different measuring strategies were made on three types of smooth tool steel surfaces. Three replica materials were tested to study possibilities within replication techniques. An optical interferometer as well as a mechanical stylus was used to evaluate the surfaces. The results showed that the tested replica materials generated good representations of both the form and the surface roughness (Sq > 300 nm). The evaluated surfaces were quite homogeneous, thus, few measurements are needed to get representative results. However, it was found that caution must be taken regarding manually polished surfaces which can be less homogenous and therefore require more measurements to get representative results.
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| 9. |
- Björck, Svante, et al.
(författare)
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A Holocene lacustrine record in the central North Atlantic: proxies for volcanic activity, short-term NAO mode variability, and long-term precipitation changes
- 2006
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 25:1-2, s. 9-32
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Tidskriftsartikel (refereegranskat)abstract
- Lake and peat corings on three Azores islands in the central North Atlantic, resulted in the discovery of a 6000 year long lacustrine sequence in a small crater lake, Lake Caveiro, on the island of Pico. This island is dominated by Pico mountain (2351 m), Portugal's highest mountain, and the lake site is situated at 903 in asl. Two sediment profiles, one central and one littoral, were sampled. Due to large facial shifts and disconformities in the littoral cores the analyses were concentrated on the central core; only the earliest 1000 years of the littoral core were studied to complement the central profile. We used sedimentology, geochemistry, diatom analyses, magnetic properties, and multivariate statistics, together with C-14 and Pb-210 dating techniques, to analyse the environmental history of the lake. Volcanic activity seems to have had a dominating impact on sediment changes and partly also on the diatom assemblages; a large number of tephras are found and seem to be connected with large (diatom) inferred pH variations. However, by a combination of methods, including multivariate techniques, we infer that precipitation changes can be detected through the volcanic noise. In the youngest part of the record (AD 1600-2000), with its decadal resolution, these humidity variations seem partly related to shifts in dominating NAO mode. The more long-term precipitation changes further back in time (350-5100 cal yr BP) roughly correspond to the well-known North Atlantic drift-ice variations as well as other North Atlantic records; low precipitation during drift-ice periods. We think these alterations were driven by changes in the thermolialine circulation as large-scale equivalences to the Great Salt Anomaly; low sea surface A temperatures and changes in circulation patterns of the central North Atlantic decreased the regional precipitation. Cooler/drier periods occurred 400-800, 1300-1800, 2600-3000, 3300-3400 and possibly also 4400-4600 cal yr BP,. while 300-400, 900-1000, 2000-2400, 3100-3200, 3800-4000 and 4700-5000 cal yr BP seem to have been more humid phases on the Azores. (c) 2005 Elsevier Ltd. All rights reserved.
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| 10. |
- Cabanettes, Frederic, 1982, et al.
(författare)
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Evaluation of cam and roller surfaces and their manufacturing process by functional characterisation
- 2008
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Ingår i: Proceedings of the Swedish Production Symposium 2008, Stockholm, Sweden. ; , s. 7-
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Konferensbidrag (refereegranskat)abstract
- Friction and wear are constant problems encountered in camshaft development. Thecontact between roller and cam is a mix of sliding and rolling which leads to a wide rangeof failure modes. The uniqueness of this contact is also due to variations all around thecam of a multitude of parameters. A previous study described surface topography as afunction of cam shape. The different types of wear mechanisms are strongly linked tocontact pressures which are also dependent on roughness. The aim of the paper is toevaluate the quality of camshafts and rollers produced with different manufacturinghistories. The evaluation utilises standard roughness parameters as well as rough contactparameters. The surfaces measurements are made by a non-contact light interferometerand a set of 3D roughness parameters is evaluated for each measure. The Greenwood-Williamson contact model has been developed and also applied to the measurements inorder to collect characteristics of the microscopic pressures. The results of the study showthe significant effect of topography variations on the tribological behaviour of the camroller contact and rank the different manufacturing processes according to functionalcharacterization. The verification of the ranking using experiments is the continuity of thisstudy.
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