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Hybrid Modeling of the N-Body Problem with Applications to Astrophysics
Full text linkOver the last years, the field of hybrid modeling, the concept of combining data-driven machine learning models and numerical solution methods to simulate a physical system, has seen an immense increase in research. This new paradigm within modeling uses its predictor capabilities from neural networks to uncover the unknown physics of the underlying system, and bridges these hidden physics with the strong mathematical foundation of numerical integrators and the governing equations of the physical system. Even though hybrid modeling is being introduced into many different fields of research, one field which so far has lacked a more detailed investigation is the field of n-body problems. This field also represents the class of non-linear systems of O.D.Es. with symplectic structure. The n-body problem has through the ages been a source of countless scientific discoveries and is still of great interest to this day. As an application, this thesis will look at the problem of n-body dynamics of planetary motion, more specifically, the simulation of the main celestial bodies of the Solar System. As the first to create a hybrid model for the n-body problem of more than 3 bodies, this thesis will show, through a series of important observations and modeling approaches, that hybrid modeling of the n-body problem can be achieved. The results will also show that the subsequent model can improve the results of a standard physics-based model, the standardized modeling approach for the n-body problem. To the best of the author’s knowledge, this thesis will also be the first to present a pure data-driven model for predicting the orbital motion of planets in our Solar System.Masteroppgave i matematikkMAB399KMAMN-MA
«Ein må tole å bli skitten på fingrane» - Ein studie av identitet og fellesskap blant unge i industristaden Odda
Full text linkDenne masteroppgåva handlar om identitet og fellesskap blant ungdom i industristaden Odda i Hardanger. Odda er ein av stadane som på byrjinga av 1900-talet var ein del av industrialiseringa i Noreg. I dag er det framleis to store fabrikkar i kommunen som sysselsett mange av innbyggjarane. Då hyrnesteinsbedrifta Odda Smelteverk vart lagt ned i 2003, vart det knytt usikkerheit til lokalsamfunnets avhengighet av industri. I nyare tid har likevel optimismen rundt dei resterande fabrikkane blomstra, blant anna grunna nye investeringar og planar om utviding. Fleire forskarar har peikt på at avindustrialisering og ein aukande servicesektor i den vestlege verda har skapt nye vilkår for identitetsdanning blant unge frå den tradisjonelle arbeidarklassen. Eg spør korleis arbeidaridentitet og fellesskapskjensle blant ungdom kjem til uttrykk i ein lokal kontekst der industrien fortsatt spelar ei viktig rolle. Med inspirasjon frå blant anna Sverre Lysgaard sin sosiologiske studie Arbeidarkollektivet frå 1961, utforskar eg om ungdommane i Odda, i hovudsak gutar som er i overgangen frå utdanning til arbeid, kjenner på ein liknande form for kollektivistisk (arbeidar)fellesskap slik som tidlegare generasjonar har gjort, eller om dei heller kan seiast å vere prega av individualiserte orienteringar. Oppgåva har ei fenomenologisk tilnærming som fokuserer på den subjektive erfaringsverda og tek for seg korleis ungdommane oppfattar seg sjølv og andre. Gjennom det sosiologiske omgrepet interseksjonalitet argumenterer eg for at sosiale kategoriar som kjønn og klasse er tett knytt opp til ungdommane si identitetsdanning. Til slutt argumenterer eg for at det antropologiske omgrepet intersection kan bidra med å gi ei breiare forståing av ungdommane i Odda si identitetsdanning, då også andre relevante differensieringskategoriar kjem til uttrykk.MasteroppgåveSANT350MASV-SAN
Source and fate of ultra-short-chain PFAS in AFFF-impacted water and biota
Full text linkMasteroppgave i kjemiKJEM399MAMN-KJE
Implications of replacing animal-sourced foods in the diet of the older population, focusing on protein intake and muscle mass : A multi-methods study of the available evidence and empirical data from Kigali, Rwanda
Full text linkBakgrunn: Inntak av animalske matvarer som inneholder proteiner av høy kvalitet, kan bidra til å forbedre proteininntaket og bevare muskelmassen hos eldre. På den annen side oppfordres forbrukere til å erstatte animalske proteiner med plantebaserte matvarer i kostholdet på grunn av den høyere miljøbelastningen. Dagens retningslinjer er basert på forskning fra høyinntektsland. Det er imidlertid ikke undersøkt hvilke konsekvenser det kan ha for det totale proteininntaket og muskelmassen å erstatte animalske matvarer fra kostholdet til eldre voksne.
Målsetting: Målet med denne doktorgradsavhandlingen var å undersøke de kostholdsmessige og ernæringsmessige konsekvensene av å erstatte animalske matvarer i kostholdet til den eldre befolkningen, med særlig fokus på proteininntaket og kroppssammensetningen hos middelaldrende og eldre voksne. Vi ville også forstå dette med perspektiver fra et lavinntektsland.
Metoder: I artikkel I ble det brukt en systematisk oversikt og metaanalysemetodikk for å evaluere dokumentasjonen for effekten av å redusere inntaket av kjøtt og/eller meieriprodukter på proteininntaket og kroppssammensetningen. I artikkel II ble det gjennomført en tverrsnittsundersøkelse av kostholdet for å vurdere inntaket av animalske matvarer og sammenhengen med proteininntak og muskelmasse hos eldre voksne. I artikkel II ble det gjennomført en kvalitativ studie for å undersøke eldre menneskers oppfatning av kjøttinntaket i kosten.
Resultater: I de kvantitative studiene observerte vi at det å erstatte animalske matvarer i kostholdet var proporsjonalt forbundet med en reduksjon i det totale proteininntaket. Metaanalysen viste ingen evidens for effekten av å redusere inntaket av kjøtt og/eller meieriprodukter på kroppssammensetningen. Derimot viste kostholdsundersøkelsen at inntak av animalske matvarer var positivt assosiert med skjelettmuskelmasse. Tre temaer ble identifisert i den kvalitative studien, og de var knyttet til opplevd tilgjengelighet og pris på kjøtt samt motiver og barrierer for kjøttforbruk.
Konklusjon: Funnene i denne avhandlingen viste at ASF spiller en uerstattelig rolle i kostholdet til eldre voksne i både høy- og lavinntektsmiljøer. Det var konsistente bevis for at det å erstatte animalske matvarer i kostholdet kan ha en negativ innvirkning på det proteininntaket hos eldre voksne. Det var imidlertid blandede resultater når det gjaldt effekten på muskelmassen.Background: The proportion of the older population is increasing both in high- and low-income countries. This population is at high risk of different forms of nutrition-related disorders, including muscle wasting and functional decline. Consumption of animal-sourced foods (ASFs), providing high-quality proteins, can contribute to improving protein intake and preserving muscle mass in older adults. On the other hand, consumers are being encouraged to replace ASFs with plant-based foods in their diets, a shift known as protein transition, because of their higher environmental burden. Current discourse on potential implications of this dietary shift on dietary intake and body composition of older population are based on research conducted mostly in high-income countries. The implications of replacing ASFs in the diet of older adults on their total (absolute) protein intake and muscle mass, particularly in low-income countries, have not been investigated. Data integrating both low- and high-income settings are needed to enrich scientific understanding and stimulate an inclusive discourse on the impact of protein transition on global aging.
Objective: The aim of this PhD thesis was to investigate the implications of replacing ASFs in the diet on dietary intake and body composition of the older population, focusing on protein intake and muscle mass.
Methods: In paper I, a systematic review and meta-analysis methodology were applied to evaluate evidence for the effect of reducing meat and/or dairy in the diet on the protein intake and body composition in middle-aged and older adults (aged ≥ 45 years). In Paper II, a cross-sectional (dietary) survey was conducted in Gasabo district, Rwanda, to assess the associations between ASF consumption and protein intake and muscle mass in community-dwelling older adults (aged ≥ 55 years). In Paper III, a qualitative study was also conducted in Gasabo district, Rwanda, to explore perceptions of dietary meat consumption in community-dwelling older adults (aged ≥ 55 years).
Results A total of 1,475 middle-aged and older adults (aged ≥ 45 years), mostly from HICs, were enrolled in the RCTs summarized in Paper I, while Paper II included 334 older adults (median age: 65 years) from Gasabo district. The findings of these two papers (quantitative studies) showed that replacing or lacking ASFs in the diet was proportionally associated with a decrease in total protein intake. In Paper I, there was no evidence of the effect of reducing meat and/or dairy consumption on muscle mass. In contrast, Paper II found that ASF consumption was positively associated with skeletal muscle mass. Paper III included 64 older adults. Three themes were identified in Paper III, relating to the perceived accessibility and affordability of meat, as well as the motives for and barriers to meat consumption.
Conclusion: The findings of Papers I and II show that ASFs play an important role in the diet of older populations in both high-and low-income settings. There was consistent evidence that replacing ASFs in the diet was associated with a decrease in total (absolute) protein intake of the study populations. There was, however, mixed evidence of the effect on muscle mass. Similarly, in Paper III, although ASF consumption was perceived to be low and declining among older adults compared to past decades, the motives for ASF consumption were perceived to be related to the role played by ASFs in sensorially and nutritionally improving diet quality, as well as in strengthening social relationships.Doktorgradsavhandlin
Sykepleie i fengsel. Hvilke situasjoner opplever helsepersonell i fengsel som utfordrende - og hvordan blir komplekse problemer løst?
No full textMasteroppgave i kommunal ledelseEXECUTIVE670EXEC67
The Impact of Norwegian language proficiency on effective communication, employee engagement and development.
Full text linkLingvistikk mastergradsoppgaveLING350MAHF-LIN
Volcanic activity and temporal evolution of ultraslow-spreading ridges
Full text linkDet overordnede målet med denne studien har vært å øke vår forståelse av vulkansk aktivitet langs jordens ultrasakte sprederygger. Avhandlingen består av tre deler som sikter mot å: (I) Forstå den romlige og tidsmessige vulkanske utviklingen av en revnedal, (II) Kvantifisere størrelsen og frekvensen av vulkanske utbrudd for å bedre forstå den årlige smelteproduksjonen ved ultrasakte sprederygger, og (III) Undersøke mantelens heterogenitet under Mohns- og Knipovichryggene for å forstå produksjonen og transporten av basaltiske smelter.
For å håndtere delmål I, benyttes 4000 km med data fra bunn-penetrerende ekkolodd samlet med autonome undervannsfarkoster for å beregne sedimenttykkelse oppå den vulkanske havbunnen langs Mohnsryggen som har skrå og ultrasakte spredning. Sedimentkjerner ble brukt til å etablere sedimentasjonshastigheter, noe som muliggjør bruk av sedimenttykkelse som en indikator for lavastrømmenes alder. Det dokumenteres at sedimentene akkumuleres generelt jevnt med en gjennomsnittlig hastighet på 6 cm/ka, dobbelt så fort som i de åpne havbassengene i Norsk-Grønlandshavet. Denne høye sedimentasjonshastigheten muliggjør en detaljert undersøkelse av vulkansk aktivitet. Det første storskala alderskartet over de øvre lavastrømmene i en revnedal presenteres, og avslører utbredt ung vulkanisme gjennom revnedalen og utbrudd som skjer over hele dens bredde. Funnene utfordrer eksisterende akse-sentrerte spredemodeller, og tyder på at vulkanske hendelser og skorpedannelse er fenomener som forekommer i hele dalen. Alderskartet viser et flekkete aldersmønster, og det foreslås at hver flekk (1-2 km2) representerer en enhetscelle i den vulkanske sekvensen. Nesten 50% av revnedalen har opplevd vulkansk fornyelse de siste 25 000 år. Videre viser alderskartet at aksiale vulkanske rygger (AVR) har vært stabile vulkanske systemer de siste 150 000 år, motstandsdyktige mot ytre faktorer som havnivåendringer og istider. Disse ryggene viser en fornyelsesrate som er dobbelt så høy som områder utenfor dem, noe som indikerer hyppigere vulkanske utbrudd innenfor AVRer, selv om de bare dekker 30% av revnedalens bunn. Dette indikerer et nesten 1:1-forhold mellom lavastrømmer mellom AVRer og områder utenfor, noe som fremhever et dynamisk og utbredt vulkansk landskap i revnedalen.
Delmål II tar for seg omfang, fordeling og morfologi av vulkanske terreng langs Mohnsryggen, med søkelys på AVRer for å estimere størrelsen og frekvensen av vulkanske utbrudd samt studere det totale magmabudsjettet. Ved å bruke høyoppløselig (1 m) batymetri og «backscatter» kart, visuelle observasjoner fra en fjernstyrt undervannsrobot, og geokronologi av basalter og sedimenter, kartlegger studien ulike vulkanske strukturer og vurderer deres volum og utbruddskarakteristikker. Funnene indikerer mangfoldige terrengtyper: 50% vulkansk hugterreng, 30% tykke sedimenter, 10% vulkanske kjegler og mindre andeler av ras og forkastningsskrenter, og flatliggende terreng som består av lobe lignende former og flakstrømmer. Volumetrisk analyse varierer fra små hauger (~0.42×106 m³) til komplekse strukturer bestående av mange hauger (38×106 m3) eller store flakstrømmer (opptil 23×106 m³). Ved å korrelere de kartlagte strukturenes størrelse med skorpens fornyelsesrater fra forrige studie, estimeres en utbruddsfrekvens ti- til hundreårsskala for hver AVR. Studien viser også et mønster av tidlige utbrudd av stort volum etterfulgt av mer hyppige utbrudd med mindre volum, noe som tyder på et syklisk vulkansk mønster i veksling med tektonisk aktivitet ved AVRer. Et årlig magmabudsjett på 2.8 - 5.2×10-3 km³ estimeres per 100 km av ryggen, og foreslår at Mohnsryggen utvikler seg gjennom høy grad av tektoniske spredning (30%) og lav smelteekstraksjon (~10%) fra den totale magmaproduksjonen.
I delmål III undersøkes mantelens heterogenitet og basaltisk smelteproduksjon under ultrasakte spredningsrygger ved å analysere geokjemien (hoved- og sporelementer) og isotopsammensetningen (Sr, Nd og Pb) av in-situ basalter fra den sentrale delen av Mohnsryggen og den nordlige delen av Knipovichryggen. Ved å bygge på tidligere funn kombinerer denne studien geokjemiske data med havbunnsobservasjoner og aldersestimater for å utforske den temporære utviklingen av mantelkilden og mekanismene for smelting og magmablanding. Ved å analysere 75 prøver dokumenteres betydelige kjemisk variasjoner i basalter fra disse ryggene. Overraskende nok viser basalt fra Mohnsryggen store isotopvariasjoner (Pb-isotoper sammenlignbare med den dokumenterte spredningen langs hele ryggene) innenfor et lite område (~1 km²), noe som tyder på en svært heterogen mantel, mens basalter fra Knipovichryggen indikerer en mer homogen mantelkilde. Høyoppløselig kartlegging kobler disse kjemiske variasjonene til vulkanske strukturer og tidsmønstre, og støtter en hypotese om flere små utbrudd og avdekker også en gradvis endring i mantelsammensetningen gjennom 30 000 år, fra anrikede til tappede kilder. Dette tyder på oppsmelting ved ulike dyp og rask smelteekstraksjon via kanaler med begrenset blanding under oppstigning.The overall aim of this study has been to better understand the volcanic activity at Earth's ultraslow-spreading ridges. The thesis comprises three parts that aim to: (I) Understand the spatiotemporal volcanic evolution of a rift valley, (II) Quantify the size and frequency of volcanic eruptions to better understand the annual melt production at ultraslow-spreading ridges, and (III) Investigate the mantel heterogeneity underneath the Mohns and Knipovich Ridges to understand the production and transport of basaltic melts.
To approach objective I, 4000 km of sub-bottom profiler data, collected with autonomous underwater vehicles, was used to calculate sediment thickness on top of the volcanic basement of the oblique ultraslow-spreading Mohns Ridge. Sediment cores aid in establishing sedimentation rates, facilitating the use of sediment thickness as a proxy for lava flow age. Data show that sediments accumulate uniformly at an average rate of 6 cm/ka, twice that of the open ocean of the Norwegian-Greenland Sea. This high sedimentation rate enables a detailed examination of volcanic activity. The first large-scale age map of upper lava flows in a rift valley is presented, revealing widespread young volcanism throughout the valley and eruptions occurring across its width. The findings challenge axial-centric spreading models, suggesting volcanic events and crustal accretion are valley-wide phenomena. The age map displays a patchy age distribution, and each patch (1-2 km2) is suggested to represent a temporal unit cell of the volcanic sequence. Nearly 50% of the rift valley has experienced volcanic renewal in the last 25 ka. Moreover, the data show that axial volcanic ridges (AVRs) have been steady-state volcanic systems for at least the last 150 ka, resilient to external factors like sea level changes and glaciations. AVRs exhibit a renewal rate twice that of areas outside them, indicating more frequent volcanic eruptions within AVRs, though they cover just 30% of the valley floor. This indicates a near 1:1 ratio of lava flow emplacement between AVRs and non-AVR areas, highlighting a dynamic and widespread volcanic landscape in the rift valley.
Objective II aims to evaluate the abundance, distribution, and morphology of volcanic terrains along the Mohns Ridge, focusing on axial volcanic ridges (AVRs) to estimate the size and frequency of volcanic eruptions, and the overall magma budget. Utilizing high-resolution (1 m) bathymetry and backscatter maps, visual ROV observations, and geochronology of basalts and sediments, various volcanic features were mapped, and their volume and eruption characteristics was assessed. Findings indicate diverse terrain types: 50% hummocky terrain, 30% thick sediment coverage, 10% volcanic cones, and smaller proportions of mass wasting features and pitted terrains comprising lobate and sheet flows. Volumetric estimates range from individual hummocks (~0.42×106 m3) to larger edifies with multiple hummocks (38×106 m3) or high effusion rate sheet flows (up to 23×106 m3). By correlating the mapped features' size with volcanic renewal rates from the previous chapter, an estimated eruption frequency suggests eruptions on a ten- to hundred-year scale on individual AVRs. The study also reveals a pattern of initial high-volume eruptions followed by more frequent, low-volume eruptions, suggesting a cyclical volcanic construction process interspersed with tectonic activity at AVRs. An annual magma budget of 2.8 - 5.2×10-3 km³ was estimated per 100 km of the Mohns ridge, and suggest that the Mohns Ridge evolves through a high degree of time-averaged tectonic spreading (30%) and low melt extraction (~10%) from overall magma production.
Objective III is approached by investigating mantle heterogeneity and basaltic melt production under ultraslow-spreading ridges by analyzing the geochemistry (major and trace elements) and isotopic composition (Sr, Nd, and Pb) of in-situ basalts from the central Mohns Ridge and northern Knipovich Ridge. Building on previous findings, this study combines geochemical data with seafloor observations and age estimates to explore the temporal evolution of the mantle source and the mechanisms of melt extraction and magma mixing. Analyzing 75 samples, the results document significant chemical variability in basalts from these ridges. Notably, basalt at Mohns Ridge showed large isotopic variations (Pb isotopes comparable to the range along the entire ridge system) within a small area (~1 km2), suggesting a highly heterogeneous mantle, whereas basalts from Knipovich Ridge indicated a more homogeneous mantle source. High-resolution mapping linked these chemical variations to volcanic features and temporal patterns, supporting a hypothesis of multiple small-volume eruptions and revealing a progressive change in mantle composition over 30 ka, from enriched to depleted sources. This suggests melting at various depths and rapid melt extraction through channels with limited mixing during ascent.Doktorgradsavhandlin
Impact of processing on nutritional composition, buffering capacity, and in vitro digestion of blue mussel products for Atlantic salmon feed
No full textThe challenges of aquaculture growth and sustainability have increased the demand for new novel feed ingredients to replace fish meal, fish oil, and soybean protein concentrate. The blue mussel has been proposed as a possible candidate for Atlantic salmon (Salmo salar) diets in Norwegian aquaculture, due to its marine nutritional profile and local upscaling potential. A three-step screening tool analyzing nutritional composition (crude protein, ash, and amino acid content), buffering capacity and in vitro solubility was used on differently processed blue mussel products (meat, slurry, silage sediment, and silage) to establish favorable candidates for in vivo trials in Atlantic salmon diets. 18 blue mussel products either raw or treated in different ways (heat, water bath and autoclave) were included in the screening. The processing method had a big effect on nutritional value, with blue mussel meat, slurry, and silage sediment found to be far superior to blue mussel silage. The buffering capacity correlated positively with the high ash content in the blue mussel silage. The in vitro digestion assay included both acidic and alkaline hydrolysis and used crude enzyme extract from sampled Atlantic salmon. E:S ratio, pH, temperature, and reaction time were optimized to best simulate the digestive physiology of Atlantic salmon. Raw, gentle treatment (water bath) and short treatment time (≤ 60 minutes) of blue mussel slurry products yielded the best solubility (mg of amino acids released/mg of sample) after in vitro digestion. Based on the three-step assessment, four out of 16 blue mussel slurry and blue mussel silage samples were selected as favorable candidates for in vivo testing in Atlantic salmon diets. These were raw blue mussel slurry, two water bathed blue mussel slurries, and autoclaved blue mussel slurry.Masteroppgave i biologiBIO399MAMN-BIOMAMN-HAVS
A computational perspective on the dynamics of early architecture
Full text linkChanges and variation in the shape of architectural remains have often been tied to changes in social structure and organization, demography, hierarchy, subsistence, mobility and more. While there is an immeasurable amount of architectural data collection, there are no agreed upon standards for documentation and analysis. Here we present for the first time an objective and repeatable method for quantifying and comparing structure forms, in an attempt to shed new light on questions of architectural dynamics. Our case study is the Neolithization process in the Near East, traditionally regarded as a change from rounded to rectangular forms. We digitize building outlines from published plan drawings and objectively quantify their two-dimensional morphology via the directionality of the normal vectors and minimum angles. This pilot study includes a sample of 118 structures deriving from 23 sites in the Mediterranean region and Jordan Valley of the southern Levant. Our results show that there is considerably more variability than can be subsumed in the traditional ‘round to rectangular’ scheme of architectural development. We identify construction of right angles as early as the Natufian and show that early architecture throughout the Natufian and Pre-Pottery Neolithic A is less restricted by formal conventions. On the other hand, during the Pre-Pottery Neolithic B, variability is more constrained, potentially suggesting a codification of architectural norms.acceptedVersio
Trend analyses of persistent organic pollutants in human milk from first-time mothers in Norway between 2002 and 2021
Full text linkIntroduction
Persistent organic pollutants (POPs) are stable compounds characterized by their resistance to degradation. From the 1960–70's organochlorine pesticides (OCPs), such as DDTs and polychlorinated biphenyls (PCBs) raised concerns regarding health and environmental impacts. This has led to the banning of POPs in the USA and Europe including Norway in 1980 and worldwide under the 2004 Stockholm Convention. The exposure of nursing infants to POPs has been a significant focus, prompting extensive research into the presence of these substances in human breast milk. In this study, we explored the temporal trends of POPs concentrations in breast milk sampled between 2002 and 2021 by comparing the concentration across the mother's year of birth.
Method
Two Norwegian cohorts of lactating women were utilized (the HUMIS study and the “Iodine in Early Life”-Study). Concentrations of 15 different POPs, including PCBs, OCPs, and brominated diphenyl ethers (BDEs) were measured in 513 breast milk samples that had been collected over two decades in a subset of first-time mothers.
Results
Time trend analysis indicated a steady decrease in concentration levels when adjusted for maternal age. The largest reduction was observed in β-HCH, age-adjusted (−17.1%, 95% CI -18.7, −15.4), followed by ∑6BDE (−9.1%, 95% CI -10.5, −7.7), ∑6PCBs (−7.1%, 95% CI -7.7, −6.5), and ∑2DDTs (−7.0%, 95% CI -8.0, −6.0). In contrast, an increasing trend was noted in the median concentrations of β-HCH, ∑2DDTs, and ∑6BDE in the mothers born in 1990–1994 to 1995–2002.
Conclusion
Our study demonstrates a decline of most POPs in breast milk, likely attributed to international regulatory efforts like the Stockholm Convention. Notably, an increase in the 95th percentile concentrations of β-HCH, ∑2DDTs, and ∑6BDEs was noted in mothers born in 1990–1994 compared to those born in 1995–2002 suggests demographic shifts that may influence exposure levels. Further research is needed to explore and understand the underlying factors for the rise in median concentrations of ∑6BDEs.publishedVersio