Geodesics in Heat

We introduce the heat method for computing the shortest geodesic distance to a specified subset (e.g., point or curve) of a given domain. The heat method is robust, efficient, and simple to implement since it is based on solving a pair of standard linear elliptic problems. The method represents a significant breakthrough in the practical computation of distance on a wide variety of geometric domains, since the resulting linear systems can be prefactored once and subsequently solved in near-linear time. In practice, distance can be updated via the heat method an order of magnitude faster than with state-of-the-art methods while maintaining a comparable level of accuracy. We provide numerical evidence that the method converges to the exact geodesic distance in the limit of refinement; we also explore smoothed approximations of distance suitable for applications where more regularity is required

Parallel Seismic Inversion for Shared Memory Systems

In this thesis will explore how a scientific application forseismic inversion can take advantage of multi-core programming on x86 architecture. The thesis will focus on most effective domain divisions, communication patterns and multithreaded scalability. Performance comparison withthe original codes will be included, as well as an evaluation of thedevelopment effort required for implementing such techniques

“Finding stability”. Experienced and measured function in patients undergoing surgery for patellar instability

Bakgrunn: Vurdering av knefunksjon er helt sentralt for diagnostikk, behandling og oppfølging av pasienter med ulike kneledds lidelser. Derfor er det behov for gyldige og pålitelige måleverktøy, inkludert pasientrapporterte utfallsmål og funksjonelle tester, for å kunne evaluere behandling og videre veilede pasienter og klinikere i beslutningstagning rundt retur til idrett. I dag mangler det etablerte retningslinjer for hvordan man best vurderer knefunksjon hos pasienter med patellainstabilitet. Derfor er det viktig å utforske hvordan pasientene selv opplever å leve med et ustabilt kneskjell og hvilke funksjonsproblemer de faktisk har. Formål: Å skaffe ny kunnskap om funksjonelle tester som brukes i avgjørelser om pasientene er klar for å returnere til idrett, i tillegg til å oversette og videre undersøke måleegenskapene til Norsk versjon av spørreskjemaet Banff Patellofemoral Instabilitets Instrument 2.0 (BPII 2.0). Videre har vi ønsket å utforske hvordan pasientene selv opplevde å leve med patellainstabilitet både før og etter kirurgi. Metoder: BPII 2.0 ble oversatt til Norsk (BPII 2.0-NO) før måleegenskapene ble undersøkt. Pasienter operert med patella stabiliserende kirurgi fylte ut BPII 2.0-NO, relaterte spørreskjema og gjennomførte funksjonelle tester før inngrepet og/eller seks måneder post operativt. Førsteinntrykk og innholds validitet, intern konsistens, test-retest reliabilitet, målefeil og konstrukt validitet ble undersøkt i studie I. For å undersøke gjennomførbarhet og egnethet av et sett med funksjonelle tester, fylte 78 pasienter fra en overlappende kohort (studie I og II) ut spørreskjema (BPII 2.0, NPI og et prosjektspesifikt aktivitetsskår) før de gjennomførte funksjonelle tester (YBT-LQ, hinketester og isokinetisk styrketest). Pasientene ble klarert for å returner til idrett hvis de passerte følgende kriterier: ≤4 cm sideforskjell i anterior retning og LSI ≥95% i sum skår på YBT-LQ, gjennomsnittlig LSI ≥85% på alle hinketestene og LSI ≥90% i isokinetisk muskelstyrke. For å utforske pasientenes opplevelser med å leve med patellar instabilitet deltok 15 pasienter i en kvalitativ studie. Intervjuene foregikk seks til 12 måneder etter kirurgi og data ble analysert med systematisk tekst kondensering. Resultater: Studie I: BPII 2.0 gav et tilfredsstillende første-inntrykk, hadde god innholds validitet og ingen gulv- eller takeffekt ble funnet. Videre hadde skjemaet svært høy intern konsistens (α 0.95) og test-retest reliabilitet ICC2.1 0.87 (95% KI 0.77-0.93). Målefeilen var lav (SEM 7.1) med en SDCind på 19.7 poeng og SDCgruppe på 2.8. Åtte av ni hypoteser som utgjorde grunnlaget for å bedømme konstrukt validitet ble bekreftet. Studie II: Sekstito pasienter (82%) gjennomførte alle de funksjonelle testene, mens bare elleve (14%) pasienter ble klarert for retur til idrett. Pasienter med bilaterale problemer hadde høyere LSI-skår sammenlignet med de med unilaterale plager, i tillegg presterte de dårligere på det kontralaterale benet. Omfanget av kirurgi (kun MPFL-R versus kombinert kirurgi) predikerte ikke selvrapportert- eller målt funksjon seks måneder etter kirurgi. Videre var det kun normalisert distanse i anterior retning i det involverte (68.5 ± 5,5 vs. 64.2 ± 7.5; P = 0,04) og det kontralaterale beinet (71.5 ± 4.0 vs. 68,0 ± 7.0; P = 0.01) som var påvirket av omfanget av kirurgi. Studie III: Deltakerne ga grundige og detaljerte beskrivelser av sine erfaringer med å leve med patellainstabilitet. Et sentralt funn var den omfattende innvirkningen instabiliteten hadde på deltakernes liv. De beskrev både mental og fysisk påvirkning. Historiene deres viste en konstant frykt for at patella skulle luksere. For flertallet var denne frykten til stede i årevis før operasjon, og noe av denne frykten opphørte ikke etter operasjon. De fire hovedtemaene fra analysene var: frykt for patella dislokasjoner påvirker daglige aktiviteter, 2) tilpasning til unngåelsesatferd, 3) å være annerledes, misforstått og stigmatisert påvirker selvfølelsen og 4) føler seg sterkere, men stoler likevel ikke helt på kneet etter operasjonen. Konklusjoner: BPII 2.0-NO viste gode måleegenskaper. Kombinasjonen av funksjonstester i studie II var gjennomførbar seks måneder etter patella stabiliserende kirurgi, men veldig få klarte testene noe som tyder på at seks måneder er for tidlig for retur til idrett testing. Foreslåtte kriterier og bruk av LSI ser ut til å være uegnet for pasientgruppen. Patellainstabilitet hadde en omfattende innvirkning på deltakernes hverdagsliv, inkludert evnen til å delta i sosiale- og fysiske aktiviteter både før og etter operasjon. Implikasjoner: Det trengs videre undersøkelser av hvilke tester og kriterier klinikere skal bruke for å vurdere om pasientene har tilfredsstillende knefunksjon for å returnere til idrett. Retur til idrett testing seks måneder etter operasjonen er for tidlig for de fleste pasienter. I tillegg bør behandlingen av disse pasientene inneholde økt oppmerksomhet mot uønskede psykologiske effekter som unngåelsesadferd.Background: Assessment of knee function after patellar stabilizing surgery is a central part of rehabilitation. Therefore, there is a need for valid and reliable tools, including both patient reported outcome measures (PROMs) and functional tests to evaluate treatment and to guide clinicians in for example return to sport decisions. Since conventional return to sport (RTS) assessment currently is lacking for patients with PI, it is important to explore how the patients experience living with this disorder and what functional problems they encounter. Purpose: To gain new knowledge about functional tests used to assess readiness for RTS and activities after surgery for PI. To examine the psychometric properties of the Norwegian version of the Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) and to deepen insights on how the patients themselves experience to live with PI before and after surgery. Methods: The BPII 2.0 was translated into Norwegian (BPII 2.0-NO) before the measurement properties were examined. Patients surgically treated for recurrent PI completed BPII 2.0-NO, related questionnaires and functional tests before and/or six months postoperatively. A sub-group of 50 patients completed the BPII 2.0-NO twice with a two-week interval. We evaluated content validity, internal consistency, test–retest reliability, measurement error and construct validity. To examine feasibility and appropriateness of the functional assessment, 78 patients from an overlapping cohort (Study I and II) completed PROMs (the BPII 2.0, the NPI and the project-specific activity questionnaire) before they underwent functional testing (Y-balance test-lower quarter (YBT-LQ), single-legged hop tests and isokinetic strength tests). RTS clearance criteria were defined as: ≤4 cm YBT-LQ test anterior reach difference between legs, leg symmetry index (LSI) ≥95% in the YBT-LQ composite score, mean sum score LSI ≥85% of all single-leg hop tests and LSI ≥90% in isokinetic quadriceps strength. To explore the experience of living with PI, 15 patients from the same cohort participated in a qualitative study, using semi-structured interviews six to 12 months after surgery. The data were analysed by systematic text condensation. Results: Study I: BPII 2.0-NO demonstrated good face and content validity. No floor or ceiling effects were found, and internal consistency was excellent (α 0.95). Test-retest reliability was high ICC2.1 0.87 (95% CI 0.77-0.93) and measurement error low (SEM 7.1) with an SDCind of 19.7 points and SDCgroup of 2.8. Eight of nine hypothesis about construct validity were confirmed. Study II: Sixty-four patients (82%) were able to complete all functional tests, while only eleven (14%) patients were deemed ready for RTS, passing all return-to-sport clearance criteria. Patients with bilateral problems had higher LSI scores compared to individuals with unilateral instability and demonstrated worse performance in the contralateral leg. The extent of surgery (MPFL-R only versus combined surgery) did not predict self-reported function or functional performance at the follow-up. Further, only normalized anterior reach distance in involved (68.5 ± 5.5 vs 64.2 ± 7.5; P=.04) and contralateral leg (71.5 ± 4.0 vs 68.0 ± 7.0; P=.01) were affected by the extent of surgery, with a minor correlation (-.234, P=.04 and -.208, P=.06). Study III: Participants offered rich and detailed descriptions of the impact and lived experience of PI. A key finding was that PI had a large impact on participants’ lives. It was described to affect their mental as well as physical well-being. Their stories display a constant fear of dislocating the patella and for the majority, this was present for years before treatment was commenced and some fear still remained after surgery. The four major themes that emerged from the data were; fear of patella dislocations governs everyday life activities, 2) adaptation to avoidance behaviour, 3) feeling different, misunderstood, and stigmatized affects self-esteem and 4) feeling stronger, but still not fully confident in the knee after surgery. Conclusion: The BPII 2.0-NO demonstrated good measurement properties. The current combination of functional tests seems feasible to conduct at six months after patellar stabilizing surgery. However, for patients with PI suggested clearance standards and the use of leg-symmetry-index seems inappropriate. PI had a far-reaching impact in participants` everyday life, affecting ability to participate in social life and physical activities both before and after surgery. Implications: Appropriate tests and the level of performance that suggests readiness for RTS after surgery for PI needs further exploration. RTS testing at six months postoperative seems premature, and patients should be informed that they probably cannot expect to return to sports at this timepoint. The overall treatment of patients with PI should incorporate increased attentions towards unwanted psychological issues such as adaptive behaviour and raised awareness of the knee both before and after surgery.Doktorgradsavhandlin

Evolution of Signals: Genetic Architecture, Natural Selection and Adaptive Accuracy

PhD i biologiPhD in Biolog

A DDFV method for a Cahn-Hilliard/Stokes phase field model with dynamic boundary conditions

International audienceIn this paper we propose a "Discrete Duality Finite Volume" method (DDFV for short) for the diffuse interface modelling of incompressible flows. This numerical method is, conservative, robust and is able to handle general geometries and meshes. The model we study couples the Cahn-Hilliard equation and the unsteady Stokes equation and is endowed with particular nonlinear boundary conditions called dynamic boundary conditions. To implement the scheme for this model we have to define new discrete consistent DDFV operators that allows an energy stable coupling between both discrete equations. We are thus able to obtain the existence of a family of solutions satisfying a suitable energy inequality, even in the case where a first order time-splitting method between the two subsystems is used. We illustrate various properties of such a model with some numerical results

Academic Performance, Health and Support Needs: Comparing Foster Care Alumni and Peers in Higher Education in Norway

The completion rates of higher education are low among young adults with a history of foster care. Understanding how students from foster care alumni fare is imperative for facilitating attainment and preventing drop-out. The aim of this study was to compare students from foster care alumni and the general student population by examining (1) sociodemographic characteristics, academic functioning and need for special assistance; (2) contextual factors important for student life; and (3) mental and somatic health, loneliness, life satisfaction and use of cannabis and alcohol. Data comprised self-reports from the Norwegian national survey Students’ Health and Well-being Study 2022. Reports from foster care alumni students (n = 508) were compared to those of the general student sample (n = 59,036). Compared to the general sample, twice as many foster care alumni students reported receiving or needing special assistance in their studies. Moreover, they reported substantially higher economic burden than their student peers, by higher frequency of work income, more financial worries, and less parental financial support. Foster care alumni students also reported a higher load of informal care responsibilities, poorer mental and somatic health, more loneliness and lower life satisfaction. Foster care alumni students fare comparably well in terms of grades and study progression despite the reported economic burden and impaired health and well-being. As these are factors shown to impact study completion, policies need to be put in place to ensure that care-experienced students receive adequate support through their young adulthood and specifically in higher education.publishedVersio

The relationship between sleep duration and physical activity level among Norwegian adolescents: a cross-sectional study

Background: Failure to adhere to sleep and physical activity recommendations among adolescents constitutes a public health problem. However, the associations between sleep duration and adolescents’ physical activity levels remain less explored. The aims of this paper were twofold: (1) to describe sleep and physical activity levels among Norwegian school-based adolescents, stratified by school level and sex and (2) to explore the association between sleep and physical activity levels. Methods: Data were derived from the 2022 Norwegian Ungdata Survey, totaling 63,113 adolescents from lower (aged 13 to 16 years) and upper (aged 16 to 19 years) secondary schools. Study variables were measured using single-item questions from the Ungdata survey and collected through an electronic questionnaire administered during school hours. Logistic regressions were performed using crude analysis and adjusted for Socioeconomic status (SES) and grade level (age). Results: In lower secondary school, 57.0% of girls and 44.7% of boys reported sleeping less than the recommended 8 h, whereas in upper secondary school, the rate was 74.9% among girls and 74.3% among boys. Girls consistently reported more sleep problems, feeling more tired at school or during activities, and less physical activity than boys across school levels. Sleep duration was a significant predictor for all levels of weekly physical activity among girls across school levels, with the highest odds revealed in upper secondary school among those being active 5 times a week (B = 1.32; 95% CI [1.24 to 1.40]). Sleep duration was a predictor for being active 5 times a week for boys across school levels (B = 1.22; 95% CI [1.17 to 1.27]).Conclusion: About half of younger adolescents and three-quarters of older adolescents do not adhere to the sleep recommendation. Lower levels of physical activity were consistently reported by girls than boys. Sleep duration consistently predicted a 20 to 30% higher likelihood of being active at least 5 days a week across sex and school levels. These findings underscore the critical role of sleep duration relations to higher physical activity levels among Norwegian adolescents. Government and policymakers should encourage healthy sleep and PA habits by explicitly incorporating guidelines into the curriculum

The Importance of Perceived Discrimination and Pre-Adoption Risk for Mental Health Problems among Young Adult Internationally Adopted Students in Norway

The research on mental health problems in adult international adoptees is limited, and while perceived discrimination has been related to increased psychological distress, less is known about its influence on more severe mental health problems. The study investigated mental health problems and the importance of pre- and post-adoption risk factors among internationally adopted students in young adulthood. Data stem from the cross-sectional SHoT study (Students’ Health and Wellbeing Study) of students in higher education in Norway where 409 (0.8%) students identified themselves as internationally adopted. The internationally adopted students reported higher levels of psychological distress and higher occurrence of self-harm, thoughts of non-suicidal self-harm (NSSH), suicide attempts and suicidal ideation compared to their non-adopted peers. Perceived discrimination was associated with increased psychological distress, and higher odds of thoughts of self-harm and suicidal ideation. Being adopted from Asia was associated with lower odds of NSSH and suicide attempts compared to other birth continents. Age at adoption was not associated with any of the mental health outcomes. The results indicate an increased risk of mental health problems for internationally adopted students and suggests that pre- and post- adoption risk factors are associated with different mental health problems.publishedVersio