Publikationer från Uppsala Universitet
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Integrating Specular Manifold Sampling in Cycles Renderer for Enhanced Specular Light Transport
No full textPhotorealistic rendering demands accurate simulation of complex light-transport phenomena, such as multi-bounce caustics generated by specular reflection and refraction. Standard path-tracing renderers, including Blender's Cycles, often struggle to efficiently capture these effects. While Cycles recently integrated Manifold Next Event Estimation (MNEE) to resolve specific refractive caustics, the technique remains limited to caustics that fall inside the caster's shadow, assumes smooth-shaded surfaces, and fails to capture refractive or reflective caustics outside shadow regions, or handle scenes with multiple concurrent specular paths. This thesis addresses these shortcomings by detailing the process of extending Cycles' framework with Specular Manifold Sampling (SMS), aiming to enhance its caustic rendering capabilities for refractive paths while documenting the significant challenges encountered, particularly with reflective interactions. The objective was achieved by enhancing Cycles' manifold-computation routines to support both reflective and refractive scenarios. New modules implement biased and unbiased SMS estimators. A stochastic initialization phase selects random surface points and microfacet normals to seed manifold exploration, enabling discovery of multiple light paths. Corresponding probability-estimation mechanisms were implemented for both the unbiased estimator (via repeated trials) and the biased estimator (via a fixed budget of unique solutions). These modules allow to skip parts of the existing direct-illumination sampling strategy. The implementation was evaluated on custom benchmark scenes featuring challenging refractive caustics. The results were assessed using metrics such as rendering time, samples per pixel (spp), root-mean-square error (RMSE), and Structural Similarity Index Measure (SSIM) against baseline Cycles with standard path tracing, and its original MNEE implementation. The primary outcome is a Cycles renderer with new capabilities for multi-bounce refractive caustics via SMS, alongside a documented account of the practical difficulties in porting such advanced research, highlighting areas where theoretical promise meets implementation complexities.This Master's Thesis was done in collaboration with the National Taiwan Normal University in the context of a dual-degree programme (Sino-Swedish Master's of Computer Science).</p
Separation of heavy metals from glycol-contaminated stormwater
No full textKadmium är en toxisk tungmetall som kan orsaka allvarliga hälsoproblem vid långvarig exponering. Vid Arlanda Airport utanför Stockholm förekommer kadmium bland annat i ytbeläggningar på flygplans landningsställ, som korrosionsskydd. Vid avisning (under vintersäsongen) spolas glykolblandningar över planen vilket frigör kadmium till spillvattnet. Från avisningsytorna leds vattnet till Sigtuna kommuns ledningsnät och hamnar slutligen i Käppala reningsverk för behandling. I samband med reningsprocessen i Käppala reningsverk produceras slam som en restprodukt och säljs som gödsel till jordbrukare. Då höga halter kadmium från Arlanda når Käppala reningsverk ackumuleras metallen i slammet och försämrar dess kvalité. Swedavia har tillsammans med Käppalaförbundet och Sigtuna kommun tagit fram en handlingsplan med mål att årsmedelvärdet av kadmium i spillvatten från Arlanda inte ska överstiga 0,10 μg/l efter 2026. I nuläget behandlas delar av spillvatten med förhöjda halter föroreningar i Kolsta reningsverk med kemisk fällning. Swedavia som ansvarar för driften på Arlanda vill undersöka möjligheten att leda in B-glykolvatten i Kolsta då det finns en överkapacitet i verket som kan nyttjas. I studien undersöktes kemisk fällning genom experiment där koagulering- och flockningsmedel tillsattes till B-glykolvatten, och pH-värdet justerades. Järnsulfat (PIX-113) och Superfloc A-1883 RS, kemikalier som används vid Kolsta reningsverk, undersöktes. Resultaten visade att 0,4 ml/L järnsulfat (PIX-113) och 2,0 ml Superfloc A-1883 sänkte kadmiumhalterna till under detektionsvärdet (<0,03 μg/l). Likaså undersöktes Superfloc C-6594, ett alternativt flockningsmedel, som uppnådde samma effekt vid dosering av 1,5 ml/L. Vid pH-justering minskade kadmiumhalterna till under detektionsgränsen vid höjning till mellan pH 6,50–7,00. Sammanfattningsvis är reningsmetoden kemisk fällning en lämplig och effektiv teknik för att rena B-glykolvatten från kadmium. Genom att behandla B-glykolvatten separat, i stället för sambehandling med ingående vatten till Kolsta reningsverk, bevaras TOC-nivåerna i spillvattnet, vilket är gynnsamt för slamproduktionen vid Käppala samtidigt som kadmium avskiljs. Metoden bidrar till att uppfylla målen i handlingsplanen och kan avsevärt minska kadmiumutsläppen från Arlandas spillvattennät innan vattnet når Käppala reningsverk och i sin tur jordbruket. Cadmium is a toxic heavy metal that can cause serious health issues with long-term exposure. At Stockholm Arlanda Airport, cadmium is found in surface coatings on aircraft landing gear, where it is used for corrosion protection. During de-icing in winter, glycol mixtures (A- and B- glycol water) are sprayed on aircraft, releasing cadmium into the wastewater. This water is led to Sigtuna Municipality’s sewage system and ultimately to the Käppala wastewater treatment plant. At Käppala, sludge is produced as a by-product and sold as fertilizer to farmers. High levels of cadmium from Arlanda accumulate in the sludge, reducing its quality. Therefore, the Käppala Association and Sigtuna Municipality have introduced an action plan aiming for cadmium in Arlanda wastewater to stay below 0.10 μg/l annually after 2026. Currently, some polluted wastewater is treated at the Kolsta plant using chemical precipitation. Swedavia, responsible for Arlanda operations, wants to investigate diverting B-glycol water to Kolsta, where excess wastewater treatment capacity is available. A study was conducted using chemical precipitation with coagulants and various flocculants, along with pH adjustments. Ferric sulfate (PIX-113) and Superfloc A-1883 RS both used at Kolsta were tested. Doses of 0.4 ml/L PIX-113 and 2.0 ml Superfloc A-1883 reduced cadmium below detection (<0.03 μg/l). Superfloc C-6594 achieved the same effect at 1.5 ml/L. During pH adjustment, cadmium levels decreased to below the detection limit when the pH was raised to between 6.50 and 7.00. Results showed chemical precipitation is effective for cadmium removal from B-glycol water. Treating it separately preserves TOC levels, which benefits sludge production. The method aligns with the action plan and can significantly reduce cadmium emissions from Arlanda before reaching Käppala and, ultimately, agriculture.
Attenuation of Self-Induced Pain in Women With Nonsuicidal Self-Injury and Healthy Controls
No full textBackground: Individuals who engage in nonsuicidal self-injury (NSSI) have a reduced pain sensitivity. Self-induced pain is attenuated compared with externally induced pain, and this phenomenon, sensory attenuation, could partly explain the insensitivity to pain in individuals with NSSI. Methods: The objective was to assess sensory attenuation in women with NSSI compared to controls. In total, 81 women aged 18-35 years, mean age 23.4 (SD = 3.9), with NSSI (n = 41) or controls (n = 40) were recruited in this cross-sectional study. Self-induced and experimenter-induced pressure pain thresholds were assessed. Correlation tests assessed possible associations between sensory attenuation and NSSI frequency, NSSI duration and conditioned pain modulation. Results: Across groups, the average self-induced pressure pain was 164.8 kPa (SE = 25.2, 95% CI = 114.8-214.7) higher than the average experimenter-induced pressure pain (d = 0.66). On average, NSSI participants displayed 106.7 kPa (SE = 42.9, 95% CI = 21.7-191.8) higher pressure pain thresholds than controls (d = 0.42), but there was no significant interaction effect for group (NSSI vs. controls) and condition (self-induced vs. experimenter-induced pain) (p = 0.102). However, a greater number of NSSI participants than controls were identified as exhibiting sensory attenuation (p = 0.022) when applying a threshold of >= 10% for sensory attenuation. Sensory attenuation correlated with conditioned pain modulation (tau = 0.17; p = 0.025), but not with NSSI frequency or duration. Conclusion: Sensory attenuation of self-induced pressure was more prevalent in participants with NSSI than in controls, but there was no evidence that sensory attenuation was related to NSSI frequency or duration. The correlation between the sensory attenuation and conditioned pain modulation may be an indication of mutual anti-nociceptive mechanisms.Significance StatementSensory attenuation of self-induced pain was present in both participants with NSSI and controls, but a greater number of NSSI participants were identified as exhibiting sensory attenuation, applying a threshold of >= 10% for sensory attenuation. Sensory attenuation may facilitate NSSI behaviour because when pain is attenuated, the pain barrier for engaging in self-harm will be reduced
Att bli ADHD – Erkännande och självacceptans i det diagnostiska gränslandet : En kvalitativ undersökning av ungdomars erfarenheter och upplevelser att leva med ADHD-liknande symtom utan formell diagnos
No full textUngdomar med ADHD-liknande svårigheter utan formell diagnos riskerar omfattande stigmatisering under en formativ period i livet, samtidigt som ungdomarna inom ramen för en medicinskt präglad diskurs inte kan anta en ADHD-identitet utan en formell diagnos. Denna uppsats undersöker dessa ungdomars identitetsutveckling i delar av deras liv, med särskilt fokus på hur narrativ kopplade till ADHD präglar ungdomarnas självförståelse. Syftet med studien är att undersöka samspelet mellan erfarenhet, tolkningsramar och den egna identiteten hos ungdomarna, och förstå hur ADHD som fenomen kan prägla ungdomars särskilda livssituation. Analysen utgår från interaktionistisk teori och dialogisk identitetsteori, vilka begreppsliggör hur människan identifierar sig genom inre dialoger, sociala interaktioner, samt av en intern-extern dialektik mellan I och Me. Studien bygger på semistrukturerade intervjuer med tio ungdomar (15–18 år) som skattat högt på etablerade självskattningar relaterade till ADHD. Materialet har analyserats med hjälp av narrativ teori och analys. Resultatet visar hur heterogena erfarenheter av tolerans, krav, miljöombyten och sociala svårigheter i olika sammanhang präglar deras självbild. Ungdomarna ses vara dubbelt stigmatiserade, när de varken lever upp till kraven som “normala” eller som ADHD-personer, och de navigerar dagligen ett diagnostiskt gränsland inom vilket de både lockas av och avvisar en ADHD-identitet. Olika sociala och medicinska förståelser av ungdomarnas beteenden och ADHD-personen präglar denna ambivalens, genom framställningar av ADHD-diagnosen å ena sidan som ett verktyg för självacceptans och erkännande, å andra sidan som stigma och reduktion av ungdomarnas livsmöjligheter. Sökandet efter ADHD-identiteten blir här en av flera tillgängliga hanteringsstrategier, en strategi genom vilken ungdomarna kan rama in sig själva i mer positiva termer
Introduction
No full textScholarly study of ancient Greek sanctuaries has tended to focus on religion and ritual, monuments, deities, sacrifice, and topography. Logistics in Greek Sanctuaries takes a completely novel perspective by shifting the focus away from the religious sphere and monumental aspects of sanctuaries to practical activity and the experience of the human visitor. Close examination of the more mundane and everyday life and activity in Greek cult places, e.g., sanitation, water and food supply, accommodation, markets, managing crowds and behavior, workers, and finances, reveals relatively unexplored facets of ancient Greek sanctuaries and offers new paths of investigation for the future.P19-0384:1_RJ / Den oheliga helgedomen? Att definiera temenos som ett rum för samspel mellan gudar och människor i antikens Grekland 600 f.Kr.-200 e.Kr. / project:716
Neural correlates of chess expertise : A systematic review of brain imaging studies comparing expert versus novice players
No full textChess expertise involves a combination of advanced cognitive skills including strategic thinking, spatial reasoning, self-regulation of arousal/stress and memory, which are reflected in distinct neural processes. However, the precise neural mechanisms underlying these adaptations remain unclear. Understanding how chess expertise shapes brain function and structure across various brain imaging modalities will enhance our knowledge of expertise-related brain function. A systematic review of 18 neuroimaging studies using fMRI, fNRIS and EEG is presented here, highlighting the neural correlates of chess expertise versus those who have less experience of chess but who can play. Articles were selected based on their use of neuroimaging techniques and their focus on identifying brain regions linked to chess proficiency. It was found that expert chess players compared to novices exhibit greater activation in the bilateral fusiform gyrus and posterior middle temporal gyrus, which are associated with visual processing and spatial perception. In addition, experts demonstrate enhanced functional connectivity in networks underlying cognitive control and decision making, including the anterior cingulate cortex and the dorsolateral prefrontal cortex. Structural differences, such as reduced grey matter volume in the occipito-temporal junction and mediodorsal thalamus, suggest dynamic neurobiological changes that may reflect increased neural efficiency in chess experts. Studies show that chess expertise is associated with both structural and functional brain changes that reflect enhanced cognitive performance. These findings highlight the potential for chess training to improve cognitive abilities, such as impulse control and self-regulation, suggesting possible applications for cognitive interventions in clinical and other populations such as military or emergency services where cognitive performance needs to be optimal under pressure
Length of stay in the emergency department and its associated input-, throughput-, and output factors at two hospitals in Sweden
No full textBackground Prolonged emergency department length of stay (EDLOS) is a worldwide issue associated with increased mortality, decreased patient satisfaction and poor quality of care. The factors influencing EDLOS have not been comprehensively studied in the context of Swedish EDs. This study's objective is to determine the input-, throughput- and output factors associated with EDLOS, at two urban EDs in Sweden. Methods Data was collected from two hospitals. All patient visits during the two-year study period were included. Patients who left without being seen by a physician were excluded. The explanatory factors included patient characteristics, medical data, and hospital bed occupancy data. Multi-variable linear regression analysis was used to test the associations between the factors and EDLOS. Results The top contributors to prolonged EDLOS were diagnostic imaging, which added between 64 and 149 min of EDLOS, diagnostic testing at central laboratory (53-99 min), followed by intra-ED zone transfer (46-94 min). Arriving during crowding or being admitted during high hospital bed occupancy had a significant but relatively small absolute effect on the outcome. Conclusions Throughput factors had far greater impact on EDLOS than both input- and output factors. Adapting strategies to the structural and procedural characteristics of each setting may enhance the effectiveness of improvement efforts. Clinical trial number Not applicable
Söt skatt, bitter rättvisa? : En analys av inkomstskillnader i konsumtionsbeteende efter införandet av sockerskatt i Storbritannien.
No full textFlera länder har infört skatt på sockersötade drycker som svar på överkonsumtionen av socker, vilket utgör ett växande folkhälsoproblem. Denna studie undersöker hur införandet av den brittiska sockerskatten Soft Drinks Industry Levy (SDIL) år 2018 har påverkat konsumtionen av beskattad sockersötad läsk. Detta med särskilt fokus på fördelningseffekter mellan inkomstgrupper, ett perspektiv som förbisetts i tidigare forskning. En kvasi-experimentell difference-in-differences-metod används för att jämföra förändringar i konsumtionen av beskattade drycker (icke-lågkaloriläsk) med obeskattade drycker (juice) före och efter skattens införande. Resultaten visar en svagt statistisk signifikans (på 10%-nivån) i konsumtionen i medelinkomstgruppen, medan inga statistiskt säkerställda effekter har observerats inom låg- och höginkomstgruppen samt mellan samtliga grupper. Resultaten tyder på att skattens effekt delvis kan ha uppstått genom förändringar i produktutbud snarare än genom konsumentbeteende.Several countries have introduced taxes on sugar-sweetened beverages (SSB) in response to the overconsumption of sugar, which constitutes a growing public health issue. This thesis examines the impact of the British sugar tax Soft Drinks Industry Levy (SDIL), implemented in 2018, on the consumption of taxed sugar-sweetened soft drinks. This with a specific focus on distributional effects across income groups, a dimension often overlooked in previous research. A quasi-experimental difference-in-differences approach is employed to compare changes in consumption of taxed (non-low-calorie soft drinks) and untaxed beverages (juice) before and after the levy’s implementation. The results show a weak statistically significant reduction (at the 10% level) in consumption among middle-income households, while no statistically significant effects have been observed within low- or high-income groups or between all groups. The findings also suggest that the effect of the tax is partly driven by changes in product supply rather than consumer behavior
Price Formation and Forecasting Models in the Electricity Market : An Analysis of the Intraday and mFRR Markets
No full textThis study investigates price formation and forecasting in the intraday and mFRR electricity markets, with a focus on the growing challenges of integrating intermittent renewable energy sources. The first part examines the development of the intraday market, particularly the introduction of intraday auctions (IDAs). While IDAs were intended to support system flexibility, trading volumes remain low, and their influence on the intraday continuous (IDC) market appears limited but increasing throughout the trading day. The second part analyzes price dynamics in the IDC market and develops forecasting models for intraday prices. The day-ahead (DA) price was identified as a strong baseline model. Forecasting was conducted using both autoregressive models and artificial neural networks (ANNs), with the ANN models generally outperforming traditional approaches. The third part focuses on the mFRR balancing market, analyzing the direction of activated balancing energy and mFRR prices. Logistic regression and ANN models were developed to predict activation direction, with ANNs achieving the highest accuracy. However, class imbalances and weak signals limited practical applicability. Finally, mFRR up- and down-regulation prices were modeled separately. While the DA price proved to be a useful baseline, ANN and ARX models offered improved performance, particularly for the down price. Overall, the results underscore the potential of machine learning approaches in electricity market forecasting, while highlighting the importance of data selection and market specific dynamics