| 1. |
- Holmberg, Joakim, et al.
(author)
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Skiing efficiency versus performance in double-poling ergometry
- 2013
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In: Computer Methods in Biomechanics and Biomedical Engineering. - : Informa UK Limited. - 1025-5842 .- 1476-8259. ; 16:9, s. 987-992
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Journal article (peer-reviewed)abstract
- This study is on how leg utilisation may affect skiing efficiency andperformance in double-poling ergometry. Three experiments wereconducted, each with a different style of the double-poling technique:traditional with small knee range-of-motion and fixed heels (TRAD);modern with large knee range-of-motion and fixed heels (MOD1) and modernwith large knee range-of-motion and free heels (MOD2). For each style,motion data were extracted with automatic marker recognition ofreflective markers and applied to a 3D full-body musculoskeletalsimulation model. Skiing efficiency (skiing work divided by metabolicmuscle work) and performance (forward impulse) were computed from thesimulation output. Skiing efficiency was 4.5%, 4.1% and 4.1% for TRAD,MOD1 and MOD2, respectively. Performance was 111, 143 and 149Ns forTRAD, MOD1 and MOD2, respectively. Thus, higher lower body utilisationincreased the performance but decreased the skiing efficiency. Theseresults demonstrate the potential of musculoskeletal simulations forskiing efficiency estimations.
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| 2. |
- Holmberg, L. Joakim, 1971-
(author)
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Musculoskeletal Biomechanics in Cross-country Skiing
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Why copy the best athletes? When you finally learn their technique, they may have already moved on. Using muscluloskeletal biomechanics you might be able to add the "know-why" so that you can lead, instead of being left in the swells.This dissertation presents the theoretical framework of musculoskeletal modeling using inverse dynamics with static optimization. It explores some of the possibilities and limitations of musculoskeletal biomechanics in cross-country skiing, especially double-poling. The basic path of the implementation is shown and discussed, e.g. the issue of muscle model choice. From that discussion it is concluded that muscle contraction dynamics is needed to estimate individual muscle function in double-poling. Several computer simulation models, using The Anybody Modeling System™, have been created to study different cross-country skiing applications. One of the applied studies showed that the musculoskeletal system is not a collection of discrete uncoupled parts because kinematic differences in the lower leg region caused kinetic differences in the other end of the body. An implication of the results is that the kinematics and kinetics of the whole body probably are important when studying skill and performance in sports. Another one of the applied studies showed how leg utilisation may affect skiing efficiency and performance in double-poling ergometry. Skiing efficiency was defined as skiing work divided by metabolic muscle work, performance was defined as forward impulse. A higher utilization of the lower-body increased the performance, but decreased the skiing efficiency. The results display the potential of musculoskeletal biomechanics for skiing efficiency estimations. The subject of muscle decomposition is also studied. It is shown both analytically and with numerical simulations that muscle force estimates may be affected by muscle decomposition depending on the muscle recruitment criteria. Moreover, it is shown that proper choices of force normalization factors may overcome this issue. Such factors are presented for two types of muscle recruitment criteria.To sum up, there are still much to do regarding both the theoretical aspects as well as the practical implementations before predictions on one individual skier can be made with any certainty. But hopefully, this disseration somewhat furthers the fundamental mechanistic understanding of cross-country skiing, and shows that musculoskeletal biomechanics will be a useful complement to existing experimental methods in sports biomechanics.
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| 3. |
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| 4. |
- Tinnsten, Mats, et al.
(author)
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Projekt Davos : hjälper längdlandslaget att åka fortare
- 2004
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In: Svensk Idrottsforskning. - Sth. : Centrum för idrottsforskning. - 1103-4629. ; 13:1, s. 25-27
-
Journal article (peer-reviewed)abstract
- DAVOS – Datorbaserade verktyg för optimering och simulering är ett EU fi nansierat (Mål 1) projekt som handlar om tillämpad teknik och tilllämpad optimering. Projektet omfattar ca 10 personer, ca 20 miljoner kr och kommer att pågå fram till 2004. Projektet drivs av institutionen för informationsteknologi och medier vid Mitthögskolan i Östersund men även personal från institutionen för teknik, fysik och matematik ingår och projektledare är docent Mats Tinnsten. I projektet ingår sex delprojekt varav två har en inriktning mot sport och sportrel aterad utrustning. DAVOS har goda kontakter med den regionala industrin, internationella universitet och forskargrupper, nationella universitet, forskargrupper och projekt. Särskilt goda och givande kontakter har projektet med Nationellt Vintersportcentrum och längdskidlandslaget samt ett antal elitskidåkare som har varit eller är studenter vid någon av teknikinstitutionerna vid campus Östersund. DAVOS handlar alltså om tillämpad teknik och optimering och verksamheten är inriktad på numeriska simuleringar och analyser av tekniska tillämpningar vilket närmast faller inom området maskinteknik och man kan ju fråga sig hur detta kan kopplas till området sport och sportutrustning. På ett alldeles naturligt sätt anser deltagarna i projektet och förhoppningsvis ska detta klarna vid genomläsning av den resterande texten.
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| 5. |
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| 6. |
- Westberg, Joakim, et al.
(author)
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The genome sequence of Mycoplasma mycoides subsp mycoides SC type strain PG1(T), the causative agent of contagious bovine pleuropneumonia (CBPP)
- 2004
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In: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 14:2, s. 221-227
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Journal article (peer-reviewed)abstract
- Mycoplasma mycoides subsp. mycoidesSC (MmymySC) is the etiological agent of contagious bovine pleuropneumonia (CBPP), a highly contagious respiratory disease in cattle. The genome of Mmymy SC type strain PUT has been sequenced to map all the genes and to facilitate further studies regarding the cell function of the organism and CBPP. The genome is characterized by a single circular chromosome of 1,211,703 bp with the lowest G+C content (24 mole%) and the highest density of insertion sequences (13% of the genome size) of all sequenced bacterial genomes. The genome contains 985 putative genes, of which 72 are part of insertion sequences and encode transposases. Anomalies in the GC-skew pattern and the presence of large repetitive sequences indicate a high genomic plasticity. A variety of potential virulence factors was identified, including genes encoding putative variable surface proteins and enzymes and transport proteins responsible for the production of hydrogen peroxide and the capsule, which is believed to have toxic effects on the animal.
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| 7. |
- Agaton, Charlotta, et al.
(author)
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Gene expression analysis by signature pyrosequencing
- 2002
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In: Gene. - 0378-1119 .- 1879-0038. ; 289:1-2, s. 31-39
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Journal article (peer-reviewed)abstract
- We describe a novel method for transcript profiling based on high-throughput parallel sequencing of signature tags using a non-gel-based microtiter plate format. The method relies on the identification of cDNA clones by pyrosequencing of the region corresponding to the 3'-end of the mRNA preceding the poly(A) tail. Simultaneously, the method can be used for gene discovery, since tags corresponding to unknown genes can be further characterized by extended sequencing. The protocol was validated using a model system for human atherosclerosis. Two 3'-tagged cDNA libraries, representing macrophages and foam cells, which are key components in the development of atherosclerotic plaques, were constructed using a solid phase approach. The libraries were analyzed by pyrosequencing, giving on average 25 bases. As a control, conventional expressed sequence tag (EST) sequencing using slab gel electrophoresis was performed. Homology searches were used to identify the genes corresponding to each tag. Comparisons with EST sequencing showed identical, unique matches in the majority of cases when the pyrosignature was at least 18 bases. A visualization tool was developed to facilitate differential analysis using a virtual chip format. The analysis resulted in identification of genes with possible relevance for development of atherosclerosis. The use of the method for automated massive parallel signature sequencing is discussed.
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| 8. |
- Andersson, Håkan, 1970-
(author)
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A Co-Simulation Tool Applied to Hydraulic Percussion Units
- 2022
-
Doctoral thesis (other academic/artistic)abstract
- In this dissertation, a co-simulation tool is presented that is meant to comprise a more comprehensive environment for modelling and simulation of hydraulic percussion units, which are used in hydraulic hammers and rock drills. These units generates the large impact forces, which are needed to demolish concrete structures in the construction industry or to fragment rock when drilling blast holes in mine drifting. This type of machinery is driven by fluid power and is by that dependent of coupled fluid-structure mechanisms for their operation. This tool consists of a 1D fluid system model, a 3D structural mechanic model and an interface to establish the fluid-structure couplings, which has in this work been applied to a hydraulic hammer. This approach will enable virtual prototyping during product development with an ambition to reduce the need for testing of physical prototypes, but also to facilitate more detailed studies of internal mechanisms. The tool has been implemented for two well-known simulation tools, and a co-simulation interface to enable communication between them has been devel-oped. The fluid system is simulated using the Hopsan simulation tool and the structural parts are simulated using the FE-simulation software LS-DYNA. The implementation of the co-simulation interface is based on the Functional Mock-up Interface standard in Hopsan and on the User Defined Feature module in LS-DYNA. The basic functions of the tool were first verified for a simple but relevant model comprising co-simulation of one component, and secondly co-simulation of two components were verified. These models were based on rigid body and linear elastic representation of the structural components. Further, it was experimentally validated using an existing hydraulic hammer product, where the responses from the experiments were compared to the corresponding simulated responses. To investigate the effects from a parameter change, the hammer was operated and simulated at four different running conditions. Dynamic simulation of the sealing gap, which is a fundamental mechanism used for controlling the percussive motion, was implemented to further enhance the simulated responses of the percussion unit. This implementation is based on a parametrisation of the deformed FE-model, where the gap height and the eccentric position are estimated from the deformed geometry in the sealing gap region, and then the parameters are sent to the fluid simulation for a more accurate calculation of the leakage flow. Wear in percussion units is an undesirable type of damage, which may cause significant reduction in performance or complete break-down, and today there are no methodology available to evaluate such damages on virtual prototypes. A method to study wear was developed using the co-simulation tool to simulate the fundamental behaviour of the percussion unit, and the wear routines in LS-DYNA were utilised for the calculation of wear.
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| 9. |
- Andersson, Håkan, et al.
(author)
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Simulation of leakage flow through dynamic sealing gaps in hydraulic percussion units using a co-simulation approach
- 2021
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In: Simulation (San Diego, Calif.). - : Elsevier B.V.. - 1569-190X .- 1878-1462. ; 111
-
Journal article (peer-reviewed)abstract
- In this study, a previously developed co-simulation method has been expanded to also simulate the dynamic behaviour of sealing gap regions in hydraulic percussion units. This approach is based on a 1D system model representing the fluid components and a 3D finite element model representing the structural parts of a hydraulic hammer. The sealing gap is a fundamental feature of a percussion unit, where the reciprocating motion of the piston is generated by the valve mechanism of the sealing gap. When the gap is closed it will prevent fluid flow between regions of different pressure levels. However, a small leakage flow through the gap will always occur which size depends on the clearance and the position of the piston. The method proposed here will take the structural motion and deformation into consideration when calculating the leakage flow. The deformed state of the structure is approximated by a cylindrical surface, in a least square manner, and communicated through the co-simulation interface to the fluid simulation module, and then used when calculating the leakage flow. This method aims at a more accurate simulation of the leakage flow that will not only yield a more realistic description of the mechanism on the local level, but also a more accurate estimation of global parameters such as overall performance and efficiency. The results indicate that the simulated leakage flow will decrease when dynamic gaps are used in comparison to static gaps, which is a consequence of the deformed structure that will generate smaller clearances. The leakage flow for the dynamic gaps will even be lower than for the static perfectly concentric case, mainly due to the reduction of clearances. The results also indicate that the dynamic eccentricity does not have a major influence on the leakage flow. The outcome from this study highlights the potentials of the described co-simulation approach for analysing the dynamics of the sealing gaps in a hydraulic percussion unit (i.e. gap heights, eccentricity ratios, etc.) including the evaluation of leakage flows and its impact on the overall performance. © 2021
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| 10. |
- Andersson, Håkan, 1970-, et al.
(author)
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Simulation of wear in hydraulic percussion units using a co-simulation approach
- 2023
-
In: International Journal of Modelling and Simulation. - : Taylor & Francis. - 0228-6203 .- 1925-7082. ; 43:3, s. 265-281
-
Journal article (peer-reviewed)abstract
- In this study, a developed co-simulation method, which couples 1D-fluid and 3D-structural models, has been utilised to simulate wear in a hydraulic percussion unit. The effect of wear is generally detrimental on performance and lifetime for such units, but can also cause catastrophic failure and breakdown, requiring a total overhaul and replacement of core components. One experiment of standard straight impact was performed to investigate the tolerance against seizure. The percussion unit was operated at successively increasing operating pressures, and the level of wear was registered at each step, until seizure occurred. The co-simulation model was used to replicate the running conditions from the experiment to simulate the structural response to be used as input for the wear routine to calculate the wear depth. The wear pattern from the simulations corresponds well to the wear pattern from the experiment. Further, the effect of a misaligned impact on wear development was also studied, as this is a loading situation that typically occurs for hydraulic percussion units. The study demonstrates that the simulation method used has a potential for simulating wear and predicting seizure in hydraulic percussion units.
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| 11. |
- Berg, Agne, et al.
(author)
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Distansutbildning och e-lärande : utmaningar, möjligheter och alternativa modeller. WP2 delrapport inom K3-projektet ”Nya vägar”
- 2020
-
Reports (pop. science, debate, etc.)abstract
- Syftet med den här rapporten är att presentera en nulägesbeskrivning av existerande nationellapedagogiska praktiker och distributionsformer för distansutbildning och e-lärande med fokuspå livslångt lärande. Som en del av detta tydliggörs begreppen distansstudier ochdistansstudent. Rapporten pekar även på de viktigaste utmaningarna för presumtiva ochnuvarande distansstudenter samt ger förslag till möjliga åtgärder för staten och lärosäten attmöta dessa utmaningar. Erfarenhets- och forskningsbaserade exempel på väl fungerandearbetssätt och åtgärder för kvalitativ distansutbildning presenteras. Denna del följs av eninternationell utblick i vilken författarna utifrån ett mer visionärt perspektiv diskuterar huralternativa sätt att organisera högre utbildning potentiellt skulle kunna erbjuda nya vägar tillhögre utbildning i hela landet. Slutligen presenteras ett antal slutsatser ochrekommendationer.Författarna är verksamma inom högre utbildning med lång erfarenhet av distans- ochcampusbaserad teknikstödd undervisning och rapporten speglar följaktligen deras samladekunskaper och erfarenheter inom området. Det innebär att denna rapport har ett fokus på demöjligheter och utmaningar som möter studenter och högskolor när högre utbildning skagöras tillgänglig för hela landet.
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| 12. |
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| 13. |
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| 14. |
- Blomqvist, My, et al.
(author)
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Cognitive ability and dental fear and anxiety
- 2013
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In: European Journal of Oral Sciences. - : Wiley. - 0909-8836 .- 1600-0722. ; 121:2, s. 117-120
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Journal article (peer-reviewed)abstract
- Dental fear and anxiety (DFA), as well as dental behavior management problems, are common in children and adolescents. Several psychological factors in the child, and parental DFA, have been studied and found to correlate to the child's DFA. The aim of this study was to investigate the relationship between cognitive ability and DFA in a population-based group of children with identified behavior and learning problems. In conjunction with a dental examination at 11yr of age, 70 children were assessed with regard to DFA using the Children's Fear Survey Schedule Dental Subscale (CFSS-DS), and their cognitive ability was assessed using the Wechsler Intelligence Scale for Children. In addition, parental DFA was measured using the Corah Dental Anxiety Scale. The results revealed that DFA was significantly correlated to verbal intelligence quotient (IQ) but not to any other cognitive index. A significant correlation was found between parental DFA and child DFA. The results indicate that the child's verbal capacity may be one factor of importance in explaining dental fear in children.
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| 15. |
- Brew, Bronwyn K., et al.
(author)
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Academic achievement of adolescents with asthma or atopic disease
- 2019
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In: Clinical and Experimental Allergy. - : Wiley. - 0954-7894 .- 1365-2222. ; 49:6, s. 892-899
-
Journal article (peer-reviewed)abstract
- BackgroundOver a fifth of children and adolescents suffer with asthma or atopic disease. It is unclear whether asthma impacts academic performance in children and adolescents, and little is known about the association of eczema, food allergy or hayfever and academic performance.ObjectiveTo examine whether asthma, eczema, food allergy or hayfever impacts on adolescent academic performance and to assess the role of unmeasured confounding.MethodsThis study used the Childhood and Adolescent Twin Study of Sweden cohort born 1992‐1998. At age 9‐12 years, parents reported on their child's ever or current asthma, eczema, food allergy and hayfever status (n = 10 963). At age 15, linked national patient and medication register information was used to create current and ever asthma definitions including severe and uncontrolled asthma for the same children. Academic outcomes in Grade 9 (age 15‐16 years) included: eligibility for high school (Grades 10‐12), and total mark of the best 16 subject units, retrieved from the Grade 9 academic register. Whole cohort analyses adjusted for known covariates were performed, and co‐twin control analyses to assess unmeasured confounders.ResultsThere were no associations found for asthma or food allergy at 9‐12 years and academic outcomes in adolescence. In addition, at age 15, there were no statistically significant associations with current, ever, severe or uncontrolled asthma and academic outcomes. Eczema and hayfever at age 9‐12 years were found to be positively associated with academic outcomes; however, co‐twin control analyses did not support these findings, suggesting the main analyses may be subject to unmeasured confounding.Conclusion and clinical relevanceHaving asthma or an atopic disease during childhood or adolescence does not negatively impact on academic performance. This information can be used by clinicians when talking with children and parents about the implications of living with asthma or atopic disease.
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| 16. |
- Brynolfsson, Patrik, et al.
(author)
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Technical note : adapting a GE SIGNA PET/MR scanner for radiotherapy
- 2018
-
In: Medical physics (Lancaster). - : Wiley-Blackwell Publishing Inc.. - 0094-2405. ; 45:8, s. 3546-3550
-
Journal article (peer-reviewed)abstract
- Purpose: Simultaneous collection of PET and MR data for radiotherapy purposes are useful for, for example, target definition and dose escalations. However, a prerequisite for using PET/MR in the radiotherapy workflow is the ability to image the patient in treatment position. The aim of this work was to adapt a GE SIGNA PET/MR scanner to image patients for radiotherapy treatment planning and evaluate the impact on signal-to-noise (SNR) of the MR images, and the accuracy of the PET attenuation correction. Method: A flat tabletop and a coil holder were developed to image patients in the treatment position, avoid patient contour deformation, and facilitate attenuation correction of flex coils. Attenuation corrections for the developed hardware and an anterior array flex coil were also measured and implemented to the PET/MR system to minimize PET quantitation errors. The reduction of SNR in the MR images due to the added distance between the coils and the patient was evaluated using a large homogenous saline-doped water phantom, and the activity quantitation errors in PET imaging were evaluated with and without the developed attenuation corrections. Result: We showed that the activity quantitation errors in PET imaging were within ±5% when correcting for attenuation of the flat tabletop, coil holder, and flex coil. The SNR of the MRI images were reduced to 74% using the tabletop, and 66% using the tabletop and coil holders. Conclusion: We present a tabletop and coil holder for an anterior array coil to be used with a GE SIGNA PET/MR scanner, for scanning patients in the radiotherapy work flow. Implementing attenuation correction of the added hardware from the radiotherapy setup leads to acceptable PET image quantitation. The drop in SNR in MR images may require adjustment of the imaging protocols.
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| 17. |
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| 18. |
- Duffy, Stephen W., et al.
(author)
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Mammography screening reduces rates of advanced and fatal breast cancers : Results in 549,091 women
- 2020
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In: Cancer. - : John Wiley & Sons. - 0008-543X .- 1097-0142. ; 126:13, s. 2971-2979
-
Journal article (peer-reviewed)abstract
- Background: It is of paramount importance to evaluate the impact of participation in organized mammography service screening independently from changes in breast cancer treatment. This can be done by measuring the incidence of fatal breast cancer, which is based on the date of diagnosis and not on the date of death.Methods: Among 549,091 women, covering approximately 30% of the Swedish screening‐eligible population, the authors calculated the incidence rates of 2473 breast cancers that were fatal within 10 years after diagnosis and the incidence rates of 9737 advanced breast cancers. Data regarding each breast cancer diagnosis and the cause and date of death of each breast cancer case were gathered from national Swedish registries. Tumor characteristics were collected from regional cancer centers. Aggregated data concerning invitation and participation were provided by Sectra Medical Systems AB. Incidence rates were analyzed using Poisson regression.Results: Women who participated in mammography screening had a statistically significant 41% reduction in their risk of dying of breast cancer within 10 years (relative risk, 0.59; 95% CI, 0.51‐0.68 [P < .001]) and a 25% reduction in the rate of advanced breast cancers (relative risk, 0.75; 95% CI, 0.66‐0.84 [P < .001]).Conclusions: Substantial reductions in the incidence rate of breast cancers that were fatal within 10 years after diagnosis and in the advanced breast cancer rate were found in this contemporaneous comparison of women participating versus those not participating in screening. These benefits appeared to be independent of recent changes in treatment regimens.
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| 19. |
- Ek, Ulla, et al.
(author)
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Academic performance of adolescents with ADHD and other behavioural and learning problems : a population-based longitudinal study
- 2011
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In: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 100:3, s. 402-406
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Journal article (peer-reviewed)abstract
- Aim: To study academic performance (final grades at the age of 16 years) in individuals with i) attention-deficit/hyperactivity disorder (ADHD) and ii) other learning and/or behavioural problems. Methods: Of a total population of 591 children, originally assessed at the age of 10-11 years, it was possible to obtain final grades for 536 16-year-olds (in grade 9). Those fulfilling the criteria for ADHD/sub-threshold ADHD (n=39) and those with 'Behaviour and Learning Problems' (BLP group), (n=80) and a comparison group (n=417) were contrasted. Results: The ADHD and BLP groups had a significantly lower total mean grade at the age of 16 years than the comparison group. In addition, the ADHD and BLP groups also qualified for further studies in the upper secondary school to a significantly lesser extent than the controls (72%, 68% and 92%, respectively). All IQ measures (at the age of 10-11 years) were positively correlated with the overall grade after grade 9, with especially strong correlations for verbal capacity. Conclusion: ADHD and similar problems entail a risk of underachievement at school. The results indicate that pupils with ADHD underachieve in the school situation in relation to their optimal cognitive capacity. The contextual situation and the particular requirements should be considered in order for adequate educational measures to be undertaken.
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| 20. |
- Ek, Ulla, et al.
(author)
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Cognitive strengths and deficits in schoolchildren with ADHD.
- 2007
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In: Acta Paediatrica (Oslo, Norway : 1992). - : Wiley. - 0803-5253 .- 1651-2227. ; 96:5, s. 756-761
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Journal article (peer-reviewed)abstract
- BACKGROUND: Few studies provide detailed analyses of the various aspects of the entire cognitive profile of children with ADHD. MATERIAL AND METHODS: Cognitive test data were analysed for 10- to 11-year-old children with (1) ADHD, (2) subthreshold ADHD and (3) milder attention and/or learning problems, and compared with normative data. RESULTS: Thirty-two had ADHD and 10 met the criteria for subthreshold ADHD, prevalence rates of 5.4% and 1.6%, respectively. On a group level, children with ADHD/subthreshold ADHD, and those with milder attention and/or learning problems had almost identical cognitive profiles for the 13 subtests comprising the WISC III, with particularly low results on the arithmetic, coding, information and digit span subtests (ACID profile). When analyzed individually, a complete or incomplete ACID profile (three of four subtests) was equally common in children with ADHD/subthreshold ADHD and in children with milder problems, found in about 1/5. The relative strengths of both groups were in areas demanding logical thinking, reasoning and common sense. CONCLUSION: The specific ACID profile is as common in children with ADHD as in those with minor attention and/or learning problems. The cognitive weaknesses reflected in the ACID profile might play a role as an underlying factor in various developmental disorders.
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| 21. |
- Ek, Ulla, et al.
(author)
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Self-esteem in children with attention and/or learning deficits : the importance of gender
- 2008
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In: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 97:8, s. 1125-1130
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Journal article (peer-reviewed)abstract
- Objective: Our objective was to analyze self-esteem in children within a spectrum of attention disorders, that is, besides attention deficit hyperactivity disorder (ADHD), also children with subthreshold ADHD and even milder attention deficits and/or learning problems.Methods: From a population-based group of 10–11-year-old children in a Swedish municipality those with ADHD/subthreshold ADHD (n = 30) and those with milder attention and/or learning problems (n = 64) were targeted for the study. The children completed the 'I think I am' scale, reflecting physical appearance, scholastic competence, mental well-being, relationships to parents and to others and global self-esteem. Data from boys and girls were compared and related to the parents' and teachers' ratings on the two dimensions of the Conners' 10-item questionnaire (impulsive-restless behaviour and emotional lability) and to the children's cognitive levels.Results: Significant gender differences were found, girls reporting lower self-esteem concerning mental well-being and poorer relationships with parents and peers. However, children with ADHD/subthreshold ADHD did not report significantly lower global self-esteem when compared to a reference population.Conclusion: Self-esteem in children with attention, behaviour and/or learning problems has to be carefully evaluated, especially in girls, and measures are needed to prevent a trajectory towards adolescent psychopathology.
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| 22. |
- Entesarian, Miriam, et al.
(author)
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A chromosome 10 variant with a 12 Mb inversion [inv(10)(q11.22q21.1)] identical by descent in the Swedish population
- 2009
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In: American Journal of Medical Genetics. - : Wiley Interscience. - 0148-7299 .- 1096-8628 .- 1552-4825 .- 1552-4833. ; 149A:3, s. 380-386
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Journal article (peer-reviewed)abstract
- We identified a paracentric inversion of chromosome 10 [inv(10)(q11.22q21.1)] in 0.20% of Swedish individuals (15/7,439) referred for cytogenetic analysis. A retrospective analysis of 8,896 karyotypes from amniocenteses in Sweden revealed a carrier frequency of 0.079% (7/8,896) for the inversion. Cloning and detailed analysis of the inversion breakpoint regions show enrichment for interspersed repeat elements and AT-stretches. The centromeric breakpoint coincides with that of a predicted inversion from HapMap data, which suggests that this region is involved in several chromosome 10 variants. No known gene or predicted transcript are disrupted by the inversion which spans approximately 12 Mb. Carriers from four non-related Swedish families have identical inversion breakpoints and haplotype analysis confirmed that the rearrangement is identical by descent. Diagnosis was retrieved in 6 out of the 15 carriers referred for cytogenetic analysis. No consistent phenotype was found to be associated with the inversion. Our study demonstrates that the inv(10)(q11.22q21.1) is a rare and inherited chromosome variant with a broad geographical distribution in Sweden.
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| 23. |
- Hindér, Gustav, et al.
(author)
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On Ski–Snow Contact Mechanics During the Double Poling Cycle in Cross-Country Skiing
- 2024
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In: Tribology letters. - : Springer. - 1023-8883 .- 1573-2711. ; 72:2
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Journal article (peer-reviewed)abstract
- Of the medals awarded during the Winter Olympics Games, most are awarded for sports involving cross-country (XC) skiing. The Double Poling (DP) technique, which is one of the sub-techniques used most frequently in XC skiing, has not yet been studied using simulations of the ski–snow contact mechanics. This work introduces a novel method for analysing how changes in the distribution of pressure on the sole of the foot (Plantar Pressure Distribution or PPD) during the DP motion affect the contact between the ski and the snow. The PPD recorded as the athlete performed DP, along with an Artificial Neural Network trained to predict the geometry of the ski (ski-camber profile), were used as input data for a solver based on the boundary element method, which models the interaction between the ski and the snow. This solver provides insights into how the area of contact and the distribution of pressure on the ski-snow interface change over time. The results reveal that variations in PPD, the type of ski, and the stiffness of the snow all have a significant impact on the contact between the ski and the snow. This information can be used to improve the Double Poling technique and make better choices of skis for specific snow conditions, ultimately leading to improved performance.
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| 24. |
- Holmberg, Anna, 1974, et al.
(author)
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Does waterborne citalopram affect the aggressive and sexual behaviour of rainbow trout and guppy?
- 2011
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In: Journal of hazardous materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 187:1-3, s. 596-9
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Journal article (peer-reviewed)abstract
- Citalopram is one of several selective serotonin reuptake inhibitors (SSRIs) commonly found in treated sewage effluents. Accordingly, there are concerns about possible adverse effects of SSRIs on aquatic organisms, particularly behavioural effects similar to those associated with SSRI use in humans. Rainbow trout fry and adult male guppies were therefore exposed to waterborne citalopram, ranging from environmentally relevant to high concentrations (1, 10, 100 μg/L) for 3-7 days. Under these experimental conditions citalopram does not appear to cause significant effects on aggression in rainbow trout fry or on sexual behaviour in male guppies. This may be explained by a relatively low uptake of citalopram from water to fish.
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| 25. |
- Holmberg, A., et al.
(author)
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The biotin-streptavidin interaction can be reversibly broken using water at elevated temperatures
- 2005
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In: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 26:3, s. 501-510
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Journal article (peer-reviewed)abstract
- The biotin-streptavidin system is the strongest noncovalent biological interaction known, having a dissociation constant, K-d, in the order of 4 x 10(-14) m. The strength and specificity of the interaction has led it to be one of the most widely used affinity pairs in molecular, immunological, and cellular assays. However, it has previously been impossible to re-use any streptavidin solid support, since the conditions needed to break the interaction with biotin has led to the denaturation of the streptavidin. Here, we show that a short incubation in nonionic aqueous solutions at temperatures above 70degreesC can efficiently break the interaction without denaturing the streptavidin tetramer. Both biotin and the streptavidin remain active after dissociation and both molecules can therefore be re-used. The efficiency of the regeneration allowed solid supports with streptavidin to be used many times, here exemplified with the multiple re-use of streptavidin beads used for sample preparation prior to automated DNA sequencing. The results suggest that streptavidin regeneration can be introduced as an improvement in existing methods and assays based on the streptavidin system as well as emerging solid phase applications in fields, such as microfluiclics and nanotechnology.
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| 26. |
- Holmberg, Joakim, et al.
(author)
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A biomechanical model of a double-poling skier
- 2003
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In: International Society of Biomechanics XIXth Congress, 6-11 July 2003, Dunedin, New Zealand, CD ROM - Abstracs and Proceeding. - Dunedin, N.Z : University of Otago.
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Conference paper (peer-reviewed)abstract
- Up till now, very little has been done in the field of cross-country skiing biomechanics using numerical techniques. This paper presents a biomechanical model of a double-poling skier that is created with the use of AnyBody, a general body-modeling and optimization software. As an aid to validate the model, a physical experiment is performed. An elite female skier is video-taped while using a double-poling ergometer. This experiment provides measurements of movement and poling power. Simulation results agree well with an experiment concerning muscle activation sequences (Nilsson and Holmberg, 2000). However, when simulation results and measured poling power are compared, agreement is not good. This means that further work on the biomechanical model is needed before it can be validated as a good representation of reality. Still, the method shows potential, and the present model could be used for initial studies of the double-poling technique. When the model is validated, it could provide a very useful tool in the quest for gold medals and perhaps, more importantly, for the prevention of injuries.
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| 27. |
- Holmberg, Joakim, et al.
(author)
-
A biomechanical model of a double‐poling skier
- 2003
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In: In International Society of Biomechanics XIXth Congress on The human body in motion, CD Rom Abstracts and Proceedings, Milburn, P. (Ed.), University of Otago, Dunedin, New Zealand, 6‐11 July.
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Conference paper (other academic/artistic)
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| 28. |
- Holmberg, Joakim, et al.
(author)
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A Musculoskeletal Full‐body Simulation of Cross‐Country Skiing
- 2008
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In: Proceedings of the Institution of Mechanical Engineers, Part P. - London : The Institution of Mechanical Engineers. - 1754-3371 .- 1754-338X. ; 222:P1, s. 11-22
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Journal article (peer-reviewed)abstract
- This paper presents a measurement-driven, musculoskeletal, full-body simulation model for biomechanical analysis of the double-poling (DP) technique in cross-country skiing. DP is a fast and powerful full-body movement; therefore, it is interesting to examine whether inverse dynamics using static optimization is working for a musculoskeletal full-body model with high accelerations, a large range of motion, and realistic loads. An experiment was carried out to measure motion and pole force of a skier on a double-poling ergometer. Using the measurement data, a simulation model was implemented in the AnyBody Modeling System (AnyBody Technology A/S, Denmark). Experimental results of motion and pole force from the DP ergometer, and also simulation results of relative muscle force profiles, are presented. These results agree with results found in literature when the kinematics and external kinetics are similar. Consequently, it should be possible to use computer simulations of this type for cross-country skiing simulations. With a simulation model, it is possible to perform optimization studies and to ask and answer ‘what if’ questions. Solutions to such problems are not easy to obtain by traditional testing alone.
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| 29. |
- Holmberg, Joakim, 1971-, et al.
(author)
-
Biomekaniska simuleringar adderar insikt om längdskidåkning
- 2010
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In: Svensk Idrottsforskning. - : Centrum för Idrottsforskning. - 1103-4629. ; 19:1, s. 38-40
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Journal article (pop. science, debate, etc.)abstract
- Varför ska man kopiera de som är bäst? När man väl lärt sig deras teknik så har de bästa kanske redan gått vidare och utvecklat ännu bättre tekniker? Med biomekaniska simuleringar adderas insikt så att man kan utveckla sin teknik och ligga i framkant, istället för i svallvågorna.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Holmberg, Joakim L., 1971-
(author)
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Computational Biomechanics in Cross-country Skiing
- 2008
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Licentiate thesis (other academic/artistic)abstract
- Traditionally, research on cross‐country skiing biomechanics is based mainly on experimental testing alone. Trying a different approach, this thesis explores the possibilities of using computational musculoskeletal biomechanics for cross‐country skiing. As far as the author knows, this has not been done before.Cross‐country skiing is both fast and powerful, and the whole body is used to generate movement. Consequently, the computational method used needs to be able to handle a full‐body model with lots of muscles. This thesis presents several simulation models created in the AnyBody Modeling System, which is based on inverse dynamics and static optimization. This method allows for measurementdriven full‐body models with hundreds of muscles and rigid body segments of all major body parts.A major result shown in the thesis is that with a good simulation model it is possible to predict muscle activation. Even though there is no claim of full validity of the simulation models, this result opens up a wide range of possibilities for computational musculoskeletal biomechanics in cross‐country skiing. Two example of new possibilities are shown in the thesis, finding antagonistic muscle pairs and muscle load distribution differences in different skiing styles. Being able to perform optimization studies and asking and answering “what if”‐questions really gives computational methods an edge compared to traditional testing.To conclude, a combination of computational and experimental methods seems to be the next logical step to increase the understanding of the biomechanics of crosscountry skiing.
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| 34. |
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| 35. |
- Holmberg, Joakim
(author)
-
Optimering av biomekaniska system
- 2001
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In: SMD 01 - Svenska mekanikdagar Linköping 11-13 juni 2001. - Stockholm : Svenska nationalkommittén för mekanik. ; , s. 195-
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Conference paper (other academic/artistic)
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| 36. |
- Holmberg, Joakim, 1971-
(author)
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Simulera med mera
- 2008
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In: CAD & ritnytt. - Malmö : Skandinaviska CADmagasin. - 0282-5708. ; :4, s. 27-28
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Journal article (pop. science, debate, etc.)abstract
- Varför tillverkar man produkter utan att ta hänsyn till människan som ska använda dem? Är det inte konstigt att det nästan inte finns någon egenskap hos tekniska produkter som inte går att simulera, men ingen vet belastningen på din ryggrad när du sitter i din kontorsstol?
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| 37. |
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| 38. |
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| 39. |
- Holmberg, Joakim, et al.
(author)
-
VerOpt - MATLAB Driven Versatile Optimization
- 2001
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In: Program and proceedings for the Nordic MATLAB Conference Oslo, October 17-18, 2001. - Trondheim : Comsol. - 8299595509 ; , s. 207-212
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Conference paper (other academic/artistic)abstract
- VerOpt, a MATLAB driven versatile optimization environment, enables the choice of a suitable optimization routine, parallelization over TCP/IP and the use of external solvers. VerOpt is the result of working towards the creation of a versatile yet effective environment for applied optimization studies. This paper presents the concepts behind VerOpt, including how and why we use parallelization, and the lessons learnt when using external solvers. The paper also gives a comparison of implemented optimization routines when applied to test problems. Currently, links to three external solvers are implemented. Two of them come from the commercial software market for engineering solutions: ANSYS (version 5.6 University High), a general purpose FE-code and C-MOLD (version 2000.7.1), a code for injection molding. The third solver is from the academic world, AnyBody, a code for biomechanical studies. The implemented optimization routines referred to are Method of Moving Asymptotes (MMA), Simulated Annealing (SA) and a genetic algorithm (GA). The MMA is a gradient-based algorithm whereas the other two can be classified as stochastic. The results of the comparison of the implemented optimization routines, in which �fmincon� from the MATLAB Optimization Toolbox is also used, show that MMA is generally the fastest routine, but does not always find the best solution. However, in test cases when parallelization is used the comparison is not ideal, since the parallelization procedures for the algorithms are not equivalent. When optimization routines are based on numerically computed gradients, such as MMA, they are embarrassingly parallel. This is because the gradients are independent of each other, which makes it possible to compute them simultaneously, but on different processors. For a stochastic routine such as SA a different approach is needed. In our case we have used a simple form of domain decomposition. An interesting result is that, in the test case involving ANSYS, we found that using ANSYS alone, as solver as well as optimizer, did not give such a good solution as using VerOpt. A clear future development is to add a greater number of different types of optimization routines. A possible future development is to transform VerOpt into something that is more akin to a regular style MATLAB Toolbox. Irrespective of this development, VerOpt will be a significant aid for education as well as research in applied optimization. It will also serve the authors as the environment for further research in the fields of injection molding and biomechanics.
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| 40. |
- Holmberg, Joakim, et al.
(author)
-
Versatile Optimization
- 2001
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In: Nordic MATLAB Conference Proceedings Oslo, Norway, October 17‐18. ; , s. 207‐212-
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Conference paper (peer-reviewed)
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| 41. |
- Holmberg, L. Joakim, 1971-
(author)
-
A simulation study on the necessity of muscle contraction dynamics in cross-country skiing
-
Other publication (other academic/artistic)abstract
- Competitive cross-country skiing is considered to be a fast and powerful dynamic movement. It is unknown what level of complexity that is needed in a musculoskeletal model of a skiing movement, e.g. double-poling. Therefore, a simulation study is carried out to explore the influence of muscle model choice. The theoretical framework of two types of muscle models and their respective implementations are given. These models are a Hill-type model with contraction dynamics and a constant force model, respectively. Results show that it is necessary to incorporate muscle contraction dynamics to estimate individual muscle behaviour in double-poling. Moreover, it may be bad practice to model different body parts with different muscle models; the musculoskeletal system is not a collection of discrete uncoupled body parts and kinetic effects will propagate through the system.
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| 42. |
- Holmberg, L. Joakim, 1971-
(author)
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Biomekanisk simulering av längdskidåkning
- 2012
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In: Svensk idrottsmedicin. - Järna : Svensk Förening För Fysisk Aktivitet och Idrottmedicin. - 1103-7652. ; 31:3, s. 11-13
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Journal article (pop. science, debate, etc.)
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| 43. |
- Holmberg, L. Joakim, 1971-, et al.
(author)
-
Can Simulations Assist in Classification Development?
- 2013
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In: Equipment and Technology in Paralympic Sports. - : International Paralympic Committee.
-
Conference paper (other academic/artistic)abstract
- There is a critical need for research that describes the extent to which impairments of varying type, severity and distribution impact performance in Paralympic sports. It is important with evidence-based judgment on how the impairments aect performance. In the following, we present a complementary evidence-based tool for classication.Let us start with an example. We recently presented a study (Holmberg et al., 2012)1 that utilized two full-body musculoskeletal simulation models of cross-country skiing (double-poling). The models were identical except that one carried no muscles in the right lower leg and foot; thus mimicking a lower leg prosthesis. It was hypothesized that a lower leg prosthesis would inuence muscular work throughout the whole body. Results showed that to generate the same motion and external work, an able-bodied skier only had to produce about 80% metabolic muscle work compared to a disabled skier (with a non-active right lower leg prosthesis).In reality there is always psychological factors present and it is probably not possible to nd two human beings (one fully functional and one impaired) with the same tness, size, strength and technique. Thus, it is hard to nd the unbiased eect of an impairment on performance in a speci c sport. The example above shows the strength of using simulations because a musculoskeletal model yields quantitative data on the unbiased eect of dierent functional impairments.In cross-country skiing, athletes with functional impairments are, in 'competition format' classification, assigned to dierent categories with weight factors. Athletes perform their race and the result list is presented as race time multiplied by weight factor. In the future, musculoskeletal simulations may assist in answering how a specic functional impairment aects performance and thereby improve the fairness in assigning weight factors for classication.
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| 44. |
- Holmberg, L. Joakim, 1971-, et al.
(author)
-
Muscle decomposition and recruitment criteria influence muscle force estimates
- 2012
-
In: Multibody system dynamics. - : Springer. - 1384-5640 .- 1573-272X. ; 28:3, s. 283-289
-
Journal article (peer-reviewed)abstract
- It has recently been pointed out that muscle decomposition influence muscle force estimates in musculoskeletal simulations. We show analytically and with numerical simulations that this influence depends on the recruitment criteria. Moreover, we also show that the proper choices of force normalization factors may overcome the issue. Such factors for the minmax and the polynomial criteria are presented.
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| 45. |
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| 46. |
- Holmberg, L. Joakim, et al.
(author)
-
Using double‐poling simulations to study the load distribution between teres major and latissimus dorsi
- 2007
-
In: In Science and Nordic Skiing, Linnamo, V., Komi, P.V. and Müller, E. (Eds.), Meyer and Meyer Sport, Oxford, UK. - : Meyer and Meyer Sport, Oxford, UK. - 9781841262291 ; , s. 81-89
-
Book chapter (other academic/artistic)abstract
- Between June 18-20 2006, the Vuokatti Sports Institute in Finland - arguably the world's finest ski training facility - played host to the International Congress on Science and Nordic Skiing."Science and Nordic Skiing" brings together the very latest in cutting edge research and developments into Nordic Skiing - ski jumping and cross-country skiing to biomechanics and the effects of cold weather on exercise - presented by some of the world's foremost experts in the field."Science and Nordic Skiing" is destined to become an invaluable and practical reference for sports scientists, coaches, skiers and anyone involved in this exciting area of winter sports.It presents the very latest research and development in the world of science and Nordic skiing.
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| 47. |
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| 48. |
- Holmberg, Max, et al.
(author)
-
On Surface Losses in Direct Metal Laser Sintering Printed Millimeter and Submillimeter Waveguides
- 2018
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In: Journal of Infrared, Millimeter and Terahertz Waves. - : SPRINGER. - 1866-6892 .- 1866-6906. ; 39:6, s. 535-545
-
Journal article (peer-reviewed)abstract
- Different lengths of WR3 (220-330 GHz) and WR10 (75-110 GHz) waveguides are fabricated through direct metal laser sintering (DMLS). The losses in these waveguides are measured and modelled using the Huray surface roughness model. The losses in WR3 are around 0.3 dB/mm and in WR10 0.05 dB/mm. The Huray equation model is accounting relatively good for the attenuation in the WR10 waveguide but deviates more in the WR3 waveguide. The model is compared to finite element simulations of the losses assuming an approximate surface structure similar to the resulting one from the DMLS process.
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| 49. |
- Jemt, Anders, 1985-, et al.
(author)
-
Evaluation of methods for whole genome and transcriptome sequencing from nanograms of FFPE samples
-
Other publication (other academic/artistic)abstract
- The most widely used method for the preservation of clinical tissue specimens is formalin fixation and paraffin embedding (FFPE). Simultaneous analysis of RNA and DNA from samples preserved using this method have long proved problematic, primarily due to lack of material. Here, we describe an attempt to build a complete analysis package for RNA and DNA extracted from single tissue sections. The workflow includes quality control of the extracted material, library preparation and data analysis. We extract DNA with varying integrity from FFPE sections and subject them to whole genome sequencing using two library preparation methods, Illumina TruSeq Nano using the Illumina NeoPrep and Rubicon Genomics ThruPlex. We are able to obtain some usable data, albeit with high duplication rates, demonstrating both the possibilities and challenges of sequencing damaged DNA. Two different approaches to transcriptome sequencing are assessed, the TruSeq RNA Access library preparation kit from Illumina and the SMARTer Stranded Total RNA-Seq Kit - Pico Input from Clonetech. The sequence capture approach of the TruSeq kit is shown to be more robust to low integrity RNA compared to the SMARTer kit. However, the SMARTer kit needs much less starting material and is able to yield data about all transcripts, not just protein coding mRNA.
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| 50. |
- Kalliorinne, Kalle, 1995-, et al.
(author)
-
A Novel Method for Quantifying Ski-Snow Friction Using an Rtk-Gnss Equipped Sled
-
Other publication (other academic/artistic)abstract
- In most winter sports, the athletes interact with snow with their equipment. In some of these sport, e.g. in cross-country skiing, a large amount of energy is spent by the athlete to overcome the restive force of friction. Consequently, a reduction in friction can be the difference between winning and coming second in a race. Over the years, researchers have come up with many ways of measuring the friction between snow and sports equipment, such as different types of skis. However, only a few of these experimental setups can be used to test the glide of real-sized skis under natural conditions during both accelerating and deceleration motion. In the present work, a novel experimental setup consisting of a sled and a base station that uses GNSS receivers communicating internally by radio, thus making up an RTK-GNSS system which can measure the position of the sled with centimetre accuracy, was established. The sled is equipped with authentic cross-country skis and accelerated and decelerated on a track with natural height variation prepared with a conventional snow-track setter mounted on a snowcat. The recorded altitude and velocity data are used to quantify the coefficient of friction (COF), both for accelerating and decelerating motion, with a model based on the preservation of energy. The results show that the COF during acceleration was more than 28% higher than during deceleration, while the difference in the COF during deceleration on flat ground at loading conditions resembling the acceleration and deceleration phases was less than 5%. This is an important discovery, as when all types of skiing techniques are executed, the athlete is either accelerating or decelerating while moving forward along the track. The ability of the current experimental set-up to distinguish between them may thus have positive implications for further development.
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