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The solutions for a class of Neutral Functional Di erential Equations (NFDE) with weakly singular kernels are studied. Using singular expansion techniques, a representation of the solution of the NFDE is obtained by studing an associated Volterra Integral Equation. We study the Collocation Method as a projection method for the approximation of solutions for Volterra Integral Equations. Particulary, the possibility of achieving higher order ap- proximations is discussed. Special attention is given to the choice of the projection space and its relation to the smoothness of the approximated solution. Finally, we study the identification problem for a parameter appearing in the weakly singular operator of the NFDE. / Ph. D.

Competing paradigms of community assembly emphasize different mechanisms for predicting patterns in biogeography. Niche assembly emphasizes the role of environmental gradients as filters that organize a metacommunity by locally selecting colonizers with similar functional traits, whereas dispersal assembly emphasizes the importance of source pool characteristics and dispersal limitation in organizing a metacommunity. In this study, I developed a framework that uses spatially explicit patterns in taxonomic and functional measures of community composition as diagnostics for community assembly processes for benthic macroinvertebrates in headwater streams in the southern Appalachians. Distance decay in taxonomic and functional similarity was used to determine the scales at which taxonomic turnover occurred within functional niches. Trait-neutral models of community composition were used as null models to assess which functional traits were the best candidates to explain how community composition was influenced by environmental gradients: an assessment of niche-based community assembly. Regional scale patterns suggested that niche-based community assembly was the dominant mechanism organizing community composition in headwater streams at local scales (<30km). Therefore, I compared how well trait-neutral models identified functional traits as relevant to community sorting against how well observed trait distributions correlated with environmental variation at a local scale, in the Ray Branch catchment (<10km study extent). Functional traits exhibiting non-random distributions within the Ray Branch watershed were most strongly correlated with environmental variation. Lastly, I assessed how the influences of niche and dispersal assembly on benthic macroinvertebrate community composition were affected by disturbance (shelterwood logging). Environmental variables defining the habitat template, and macroinvertebrate community composition, were measured before and after the disturbance; and path analysis was used to quantify the disturbance effect. The relationship between environmental variation and functional composition increased following logging, indicating disturbance augmented the influence of environmental filters, and consequently, the importance of niche-based community assembly. My dissertation provides the framework for a novel assessment of taxonomic and functional community composition data to infer the types of ecological dynamics that organize communities in the landscape. Additionally, this work provides a theoretical basis for assessing how dominant ecological processes change, in predictable ways, in response to changes in the habitat template. / Ph. D.

Yes / This paper compares several widely-used and recently-developed methods to extract risk-neutral densities (RND) from option prices in terms of estimation accuracy. It shows that positive convolution approximation method consistently yields the most accurate RND estimates, and is insensitive to the discreteness of option prices. RND methods are less likely to produce accurate RND estimates when the underlying process incorporates jumps and when estimations are performed on sparse data, especially for short time-to-maturities, though sensitivity to the discreteness of the data differs across different methods.

I denna kvalitativa intervjustudie har syftet varit att undersöka hur fem gymnasielärare i samhälls­kunskap förhåller sig till de egna åsikterna i undervisningen om politik och politiska frågor. Huruvida lärare bör vara transparenta eller förtegna med sina personliga politiska åsikter i under­visning förefaller vara en fråga i vilken meningarna går isär. Studien har syftat till att genom empirin explicitgöra de olika hållningar som lärarna intar i undervisningen och hur dessa motiveras av lärar­na. Vidare har lärarnas uppfattningar om hur de olika hållningarna påverkar undervisningen och elevernas politiska uppfattningar undersökts. Ásgeir Tryggvasons använder begreppen objektivitet och neutralitet för att beskriva hur lärare kan förhålla sig till de personliga åsikterna i under­visningen. Dessa begrepp graderas i stark och svag. Neutral är den lärare som är förtegen med de egna åsikterna i undervisningen. En objektiv hållning är liktydigt med en lärare som är transparent med vad denne tycker men som bedriver en allsidig undervisning. Dessa hållningar har fungerat som det teoretiska ramverket för uppsatsen och har använts som ett verktyg för kodning och tema­tisering av det empiriska materialet. De hållningar som explicitgjorts hos de enskilda lärarna visar på en mångtydighet och komplexitet. Samtliga lärare, förutom en, diskuterade för- och nackdelar med både en starkt neutral och en svagt neutral hållning. De undersökta lärarna har utifrån sina övergripande hållningar sorterats in i tre olika grupper. Två av lärarna föredrog en starkt neutral hållning i kombination med en starkt objektiv hållning. Den andra gruppen består också av två lärare, vars hållningar kan etiketteras som starkt objektiva men svagt neutrala. En av de undersökta lärarna har fått utgöra en egen kategori. Denne har en svagt neutral hållning och den objektiva hållningen kan beskrivas som kluven mellan både stark och svag objektivitet.

Two neutral beam injectors (NBIs) were installed on the COMPASS tokamak as a main upgrade after its move from the UK to Prague. The thesis deals with general experimental specifications of additionally heated plasmas by the NBI under the wide range of conditions on the COMPASS tokamak. The geometrical parameters of the beams are determined from the spectro- scopic measurements. Consequently, the NBI power passing through the narrow duct connecting NBI and tokamak chamber is investigated. The passing fraction of the NBI power is confirmed by the power balance analysis, which provides information about the delivered power into the plasma based on the plasma parameters. Once the delivered power is well known a description of beams interaction with plasma via global parameters such as the plasma temperatures, the plasma density, the energy confinement time and neutron yield is given. It is shown, that the NBIs heat mostly ions, which can reach ∼ 1 keV in the plasma core. Moreover, the impact of the fast ions presence on the commonly observed MHD activities, the sawtooth instability and the edge localized modes (ELMs), is discussed and compared with results from other tokamaks. The sawtooth period is prolonged by the influence of the NBI from 2 ms up to 4.5 ms. The knowledge of the NBI passing power into...

Antalet ungdomar och särskilt flickor som slutar med sport i tonåren har ökat senaste decenniet. Eftersom fysisk aktivitet främjar hälsan är det viktigt att vi försöker vända trenden. Studien ämnade skapa ökad förståelse för varför vissa personer slutar tidigare än andra, genom att undersöka hur kön, sporters könskodning samt maskulin och feminin personlighet (MF-poäng) baserat på Big Five Inventory (BFI 44) påverkar deltagande och avslut i sport. Antalet deltagare var 6 139, och tre grupper skapades; de som slutat i sin sport innan 20 års ålder, de som slutat i sin sport efter 19 års ålder och de som fortfarande var aktiva. Två studier genomfördes, först en systematisk översikt av könskodning av sport, som gav värden för 123 sporter på hur maskulin-feminin de har skattats. Analyserna visade att kön predicerar vilken grad av maskulint eller feminint kodad sport man väljer att delta i, där män väljer mer maskulint kodade sporter och vice versa för kvinnor. Maskulina personlighetsegenskaper predicerade att pojkar och aktiva män valde maskulint kodade sporter, och vice versa för flickor och aktiva kvinnor. Pojkar och män var aktiva i sin sport fler år än flickor och kvinnor. Deltagande i en feminint kodad sport predicerade att flickor var aktiva längre. Maskulin och feminin personlighet predicerade inte antalet aktiva år inom sport. Mer kunskap behövs för att behålla så många som möjligt aktiva så länge som möjligt, oavsett typ av sport och kön. / The rate of adolescents, especially girls who are quitting sports has increased in the last decade. Since physical activity is an important factor for good health, it´s important that we try to turn the trend around. The aim of the present study was to understand why some people are quitting sports earlier than others, by examining how sex, sports gendertyping, and masculine and feminine personality (MF-score) based on the Big Five Inventory (BFI 44) affect participation and termination in sport. The sample size was 6 139 and three groups were created, adolescents that stopped doing their sport before age 20, adults that stopped doing their sport after age 19,and adults that were still active. Two studies were conducted, a systematic review of sports gendertyping, which provided values on how masculine-feminine each of 123 sports have been rated. The analyses showed that sex is a significant predictor of sport choice. Males chose more masculine sports, and vice versa for females. Masculine personality predicted choice of masculine coded sports for boys and active males, and vice versa for girls and active females. Boys and men were also active in sports more years than girls and women. Feminine sports predicted more active years among girls. Masculine and feminine personality did not predict how many years participants were active in the sport. Further knowledge is needed to keep as many active as long as possible, regardless of type of sport and sex.

The high penetration of renewable energy and the emerging concept of micro-grid system raises challenges to the high power conversion techniques. Multilevel converter plays the key role in such applications and is studied in detail in the dissertation. The topologies and modulation techniques for multilevel converter are categorized at first by a thorough literature survey. The pros and cons for various multilevel topologies and modulation techniques are discussed. The 3-level neutral point clamped (NPC) topology is selected to build a 200kVA, 20 kHz power conversion system. The modularized phase leg building block of the converter is carefully designed to achieve low loss and stress for high frequency and high power operation. The switching characteristics for all the commutation loops of 3-level phase leg are evaluated by double pulse tests. The switching performance is optimized for loss and stress tradeoff. A detailed loss model is built for system loss distribution and loss breakdown calculation. Loss and stress for the phase leg and 3-phase system are quantified at all power factors. The space vector modulation (SVM) for 3-level NPC converter is investigated to achieve loss reduction, neutral voltage balance and noise reduction. The loss model and simulation model provides a quantitative analysis for loss and neutral voltage ripple tradeoff. An improved SVM method is proposed to reduce NP imbalance and switching loss simultaneously. This method also ensures an evenly distributed device loss in each phase leg and gives a constant system efficiency under different power factors. Based on the improved modulation strategy, a new modulation scheme is then proposed with largely reduced conduction loss and switching stress. Moreover, the device loss and stress distribution on a phase leg is more even. This scheme also features on the simplified implementation. The improved switching characteristics for the proposed method are verified by double pulse tests. Also the system loss breakdown and the phase leg loss distribution analysis shows the loss reduction and redistribution result. The harmonic filter for the grid interface converter is designed with LCL topology. A detailed inductor current ripple analysis derives the maximum inductor current ripple and the ripple distribution in a line cycle. The inverter side inductor is designed with the optimum loss and size trade-off. The grid side inductor is designed based on grid code attenuation requirement. Different damping circuits for LCL filter are evaluated in detail. The filter design is verified by both simulation and hardware experiment. The average model for the 3-level NPC converter and its equivalent circuit is derived with the consideration of damping circuit in both ABC and d-q frame. The modeling and control loop design is verified by transfer function measurement on real hardware. The control loops design is also tested and verified on real hardware. The interleaved DC/DC chopper is introduced at last. The different interleaving methods and their current ripple are analyzed in detail with the coupled and non-coupled inductor. An integrated coupled inductor based on 3-dimentional core structure is proposed to achieve high power density and provide both CM and DM impedance for the inductor current and output current. / Ph. D.

Eine Suche nach langlebigen, schweren neutralen Leptonen ($\mathcal{N}$) in 139~fb$^{-1}$ mit $\sqrt{s}=13$~TeV $pp$ Kollisionsdaten der Jahre 2015-2018 mit Hilfe des ATLAS-Detektors am Large Hadron Collider ist präsentiert. Die $\mathcal{N}$ werden in $W \rightarrow \mathcal{N} \mu$ oder $W \rightarrow \mathcal{N} e$ produziert und zerfallen in zwei geladene Leptonen und ein Neutrino. Die Zerfallsprodukte des $\mathcal{N}$ bilden eine einzigartige versetzte Vertex-Signatur. Die $\mathcal{N}$ Masse wird mit Hilfe einer neuartigen Technik rekonstruiert und genutzt, um zwischen Signal- und Untergrundereignissen zu differenzieren. Es wurden keine Signalereignisse beobachtet, Sensitivitätsgrenzen werden auf die quadrierten Mischungsparameter zwischen rechtshändigen und linkshändigen Neutrinos für den $\mathcal{N}$ Massenbereich von $3$~GeV~$< m_{\mathcal{N}} < 15$~GeV gesetzt. Zum ersten Mal werden diese Sensitivitätsgrenzen für Kopplungen für einen Neutino-Flavour, aber auch für Kopplungen für mehrere Neutrino-Flavour-Mischungsverhältnisse angegeben, die mit den gemessenen Neutrino-Oszillationsdaten für die invertierte und normale Massenhierarchie übereinstimmen. Zusätzlich zu der bereits abgeschlossenen Suche nach $\mathcal{N}$ werden laufende Aktivitäten skizziert, die 66~fb$^{-1}$ und $\sqrt{s}=13.6$~TeV $pp$ Kollisionsdaten der Jahre 2022-2023 des ATLAS-Detektors und semi-leptonische $\mathcal{N}$ Zerfälle in ein geladenes Lepton und ein geladenes Pion einbeziehen. / A search for a long-lived, heavy neutral lepton ($\mathcal{N}$) in 139~fb$^{-1}$ of $\sqrt{s}=13$~TeV $pp$ collision data collected between 2015 and 2018 by the ATLAS detector at the Large Hadron Collider is presented. The $\mathcal{N}$ is assumed to be produced via $W \rightarrow \mathcal{N} \mu$ or $W \rightarrow \mathcal{N} e$ and decays into two charged leptons and a neutrino, forming a unique displaced vertex signature. A novel technique is used to reconstruct the $\mathcal{N}$ mass that discriminates between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the $\mathcal{N}$ with the left-handed neutrino states for the $\mathcal{N}$ mass range $3$~GeV~$< m_{\mathcal{N}} < 15$~GeV. For the first time, limits are given for both single-flavour and multi-flavour mixing scenarios motivated by neutrino-flavour oscillation results for both the normal and inverted neutrino-mass hierarchies. In addition to the concluded search for $\mathcal{N}$, ongoing efforts are outlined that include 66~fb$^{-1}$ of $\sqrt{s}=13.6$~TeV $pp$ collision data collected between 2022 and 2023 by the ATLAS detector and semileptonic $\mathcal{N}$ decays into a charged lepton and a charged pion.

<p>Neutralsulfitkokning av björk möjliggör ett högt utbyte av hemicellulosa, vilket bidrar positivt till flutingens egenskaper och minskar vedkostnaden. Neutralsulfitkoket ska avbrytas när delignifieringen nått tillräckligt långt för att veden ska kunna defibreras skonsamt med en rimlig energiinsats, men innan nedbrytningen av hemicellulosa hunnit accelerera. Syftet med detta examensarbete var att undersöka utbytets och malningens inverkan på NSSC-massans egenskaper.</p><p>En laboratoriestudie genomfördes där massan kokades till olika utbyten och maldes vid olika insatser. Resultatet av den studien användes sedan för att ställa om kokaren och raffinörerna på lämpligt sätt vid fabriksförsöken. Massaprover togs ut efter det andra kvarnsteget och skickades för analys. De mest väsentliga egenskaperna för fluting testades genom CCT (Corrugated Crush Test), CMT (Concora Medium Test) och SCT (Short Span Compression test) men övriga konventionella egenskaper testades likväl. En avgörande egenskap för fluting är också dess krypstyvhet som undersöktes på laboratorie genom isokrona kryptester. För att få en djupare förståelse för NSSC-massans egenskaper samt kokningens och malningens inverkan på dessa utfördes även fiberkaraktärisering.</p><p>Resultatet visar att styrkan på NSSC-massan kan påverkas genom att variera både utbytet och effekten i raffinörerna. För att åstadkomma en signifikant styrkeökning krävs ett lågt utbyte tillsammans med en hög effekt i raffinörerna. Kraftiga ändringar av dessa parametrar leder dessvärre till att papperets egenskaper förändras i den grad att körbarheten på maskin kan påverkas. Studien visar även att fluting som uppfyller dagens riktvärden kan framställas kostnadseffektivt genom ett högt utbyte i kokaren och en hög insats i raffinörerna. Samtidigt erhålls då en ljusare massa, vilket kan vara betydande i vissa fall. Krypmätningarna visar samtidigt att malningen i positiv bemärkelse påverkar krypstyvheten medan utbytets inverkan är mer svårtolkat. Ett allt för högt utbyte verkar dock vara negativt ur krypstyvhetssynpunkt.</p> / <p>Neutral sulphite cooking of birch enables a high yield of hemicelluloses. This contributes positively to the properties of the flute, reduces the amount of wood needed and hence the cost. The neutral sulphite cook is to be terminated when the delignification has gone sufficiently far so that the wood can be refined mercifully with a reasonable energy input, but before the delignification has gone so far that the degradation of hemicelluloses has started to accelerate. The objective with this thesis was to examine how yield and refining affects the properties of the NSSC pulp.</p><p>A laboratory study was performed where the pulp was cooked to different yields and then beaten with different energy inputs. The results from this study were then used to determine how to set the boiler and the refiners appropriately in the paper mill trials. Pulp samples were collected after the second refiner and were then sent for analysis. The most important properties for flute were tested through CCT (Corrugated Crush Test), CMT (Concora Medium Test) and SCT (Short Span Compression test). More conventional properties were tested as well. Another important property for flute, the creep resistance, was tested in the laboratory through isochronous creep tests. To get a deeper understanding of the properties of NSSC-pulp, along with the effects of cooking and refining, fiber characterization was also performed.The results indicate that it is possible to affect the strength properties on the NSSC pulp by varying both the yield and the energy input in the refiners. To accomplish a large increase in strength, a relatively low yield is needed, along with increased refining. Large changes of those parameters may unfortunately lead to changes in paper properties in such a way that the runability on the paper machine is affected.</p><p>The results also indicate that it is possible to manufacture flute in a more cost efficient way by lowering the H-factor in the boiler while increasing the degree of refining, still keeping the strength properties above the critical values.A pulp with a higher brightness is also acquired when running the mill this way, which can be important in some aspects. The creep studies indicate that increased refining has a positive effect on the creep resistance. It is harder to make conclusions about the impact of yield, but it seems as though all too high yields affects the creep resistance negatively.</p>