Publikationer från Stockholms universitet
Not a member yet
31237 research outputs found
Sort by
Structure determination of beam-sensitive materials by 3D electron diffraction : From pharmaceuticals to porous materials
No full textThree-dimensional electron diffraction (3DED) has become a powerful method for structure determination of nano-/micron-sized crystalline materials. Due to their negative charge, electrons interact with both atomic nuclei and surrounding electron clouds in matter. While this strong interaction enables the study of nano-/micron-sized crystals, it also induces electron-beam damage during 3DED experiments. When electrons interact with a crystal, they can cause atomic displacement and bond breakage, which affects the structure and/or the chemistry of the specimen. This damage poses a significant challenge for 3DED studies of beam-sensitive materials. In this thesis, eight beam-sensitive crystalline materials were investigated using 3DED, including pharmaceuticals, zeolites, and metal-organic frameworks (MOFs). To address electron-beam damage, several data acquisition strategies were developed to preserve beam-sensitive materials during 3DED experiments. These strategies include: 1) using low electron fluence, 2) cryo-cooling, and 3) the low-dose cryo-cRED (cryogenic continuous rotation electron diffraction) method, which combines the former two. These strategies reduce electron-beam damage and enhance the reliability of 3DED. Additionally, a glovebox-assisted sample preparation workflow was developed to prepare cryo-samples under a controlled atmosphere. This approach enables 3DED studies of beam-sensitive materials that are also sensitive to air. Using 3DED at room temperature, two new piroxicam (PXM) polymorphs were identified. To mitigate electron-beam damage, the cumulative electron fluence per dataset was reduced by adjusting data acquisition parameters related to electron flux and recording time. The structure information provided insight into the structure–property relationship between hydrogen bonding and melting point. Furthermore, the structure of anhydrous sodium valproate was determined for the first time using 3DED. To address its sensitivity to both electrons and moisture, a glovebox was used to preserve the anhydrous structure during the cryo-sample preparation. Cryogenic cooling was then employed during data collection to reduce electron-beam damage. Moreover, the structure of ZMQ-1, the first stable meso-microporous aluminosilicate zeolite, was uncovered using 3DED. To determine the position of the organic structure-directing agents (OSDAs), the low-dose cryo-cRED method was employed to stabilize OSDA molecules against electron-beam damage. Likewise, three isostructural aluminum(III)-monocarboxylates (CAU-71-X, where X = Ac, Prop, and TGA), were studied using low-dose cryo-cRED. This combined method stabilized the highly flexible ligands, enabling both structure determination and positional disorder refinement of the CAU-71 compounds
Pedagogisk meritering på tvärs med lokala traditioner och disciplinära synsätt
No full textI det här kapitlet belyser jag hur lokala traditioner manifesteras vid pedagogisk meritering. Med exemplifieringar från medicinsk och teknikvetenskaplig fakultet samt hälso- och sjukvårdskontext är syftet att synliggöra förgivettagna sanningar och bidra med reflektioner och perspektiv på vad pedagogisk meritering kan vara. Med ett inifrånperspektiv belyser jag hur karriärvägar och olika modeller för lärares meritering har formats utifrån disciplinära och professionsrelaterade synsätt och organisatoriska behov. Exemplen utgår ifrån sådant som har diskuterats nationellt och som befästs inom den högskolepedagogiska diskursen, såsom den pedagogiska portföljen och hur den synliggör lärarens reflektioner över didaktiska val, antaganden och studentcentrering. Genom att belysa införandet av pedagogisk meritering vid verksamhetsförlagd utbildning hoppas jag också bredda perspektivet om hur vi kan arbeta för att främja gott lärarskap och stärka alla delar som ingår i studenters utbildning
Doing Things With Rings : Amulet rings in the Late Iron Age of eastern Middle Sweden (550-1100 CE)
No full textDoing Things With Rings investigates a range of rituals involving amulet rings, and how this set of practices can serve as a window onto some of the broader themes at play in the religious life of eastern Middle Sweden during the Late Iron Age. Though it has become increasingly clear that using amulet rings was a characteristic manifestation of the forn siðr (‘ancient traditions’) current in this region during this period, there has been little research specifically dedicated to studying these practices or considering varied facets of this phenomenon in a more holistic way. This thesis addresses these issues by employing a fine-grained ‘bottom-up’ archaeological approach to analyze a variety of assemblages that incorporate amulet rings from three different case sites located in the Mälardalen area: the gravefield designated RAÄ Söderby 28 on the island of Lovö, a ‘cult place’ discovered at Gruffet in Västmanland, and a Late Iron Age farmstead excavated at Viggbyholm, in Täby parish north of Stockholm. The physical evidence at the core of the case studies is in turn explored further in combination with the archaeology from comparable sites, other types of sources, and through the lenses of new materialist conceptions of ritualization, assemblage, relationality, and affect, in order to flesh out the most detailed and vivid possible picture of the events in question. The resulting image not only serves to reveal more about specific ritualized actions involving amulet rings but also allows us to approach something of the lived experiences of the people who carried out these actions. This process of working from apparently static objects all the way through to the dynamic (intra)actions that constituted amulet ring practices presents an example of the possibilities afforded by taking a more affective and relational approach to the archaeology of ritual
Can AI-generated music induce emotions? A mixed-methods research study on the emotional impact of AI-generated music
No full textGenerative AI and its capabilities are impacting the traditional notions of music production, as the continuous development of music generation systems grants a fundamentally different perspective on music production and the way humans engage with music. While there indeed is potential in this development, AI-generated music is perceived by many as incapable of having any aesthetic impact as it would be unable to evoke emotions, which is the primary reason humans listen to music. Suppose Generative AI is to be of any significance, in that case, it is crucial to understand how humans engage with AI-generated music by studying the emotions experienced towards this music and if any intent is ascribed to it, two essential factors in the aesthetic experience of music. Unfortunately, this aspect has been underexposed in scientific research and requires additional attention. Therefore, this thesis investigates how listeners perceive the emotional impact of AI-generated music. This is done using a mixed-methods research strategy, combining an experimental- and phenomenological approach. A single-factor within-subjects experiment was designed to present musical stimuli of both human- and AI origin, assessing listeners’ emotional responses and perceptions of intentionality. This data was further explored through semi-structured interviews to investigate the phenomenon thoroughly. The thesis findings reveal that listeners experience emotions towards AI-generated music and generally ascribe intent behind the music, even when perceiving a piece of music to be of AI origin. However, a vital factor is how this music is presented, as the context in which the music is played, and the listener’s perception of the artist are crucial factors in the acceptance of AI-generated music. While the thesis is primarily exploratory and should be considered within the context of a Master’s thesis, it provides unique contributions to human-computer interaction. It challenges the traditional notions about AI-generated music, suggesting it cannot be emotionally impactful. The thesis findings give new insights into how this music could be applied in society and provide a fundamental stepping stone for further research
Sensorer för inkluderande Virtual Reality-spel
No full textDenna kvalitativa studie, i form av ett utforskande experiment, undersökte hur virtual reality (VR)-spelupplevelser kan designas med olika sensorer för att vara mer inkluderande för personer med intellektuell funktionsnedsättning (IF). Data samlades genom observation och semistrukturerade intervjuer med en VR-spelprototyp. Sex deltagare , som alla var personal som arbetade med personer med funktionsnedsättning, deltog i studien. Studien fann att VR-kontroller, när de används för att efterlikna enkla, konkreta och upprepbara mönster, hade en positiv mottagning. Joystick hade blandade resultat och uppfattades som mindre intuitiv på grund av designval, men kan ändå spela en roll i inkluderande VR-miljöer. Röststyrning visade sig vara det mest lovande alternativet, med förbättringspotential gällande precision och svarstid. En viktig slutsats är att VR-glasögons design bör förbättras för att minska känslan av instängdhet och öka tillgängligheten. Slutligen betonar studien att integrera inmatningsmetoder tidigt i designprocessen kan skapa mer inkluderande upplevelser.This qualitative study, in the form of an exploratory experiment, investigated how Virtual Reality (VR) gaming experiences can be designed using various sensors to be more inclusive for people with intellectual disabilities (ID). Data was collected through observation and semi-structured interviews with a VR game prototype. Six participants , all of whom were staff working with individuals with disabilities, took part in the study. The findings suggest that VR controllers, when designed to replicate simple, concrete, and repeatable patterns, were well-received. Joystick had mixed results and were considered less intuitive due to design choices, but could still contribute to inclusive VR environments. Voice control was the most promising option, with room for improvement in terms of accuracy and response time. An important conclusion is that the design of VR headsets should be improved to reduce the feeling of confinement and enhance accessibility. Finally, the study emphasizes the importance of integrating input methods early in the design process to create more inclusive experiences
Unity vs. Unreal Engine: A performance test
No full textIntroduktion: Den här studien jämför två av de mest använda spelmotorerna Unity och Unreal Engine i syfte att avgöra hur väl de presterar jämfört med varandra vid objektgenerering. Tidigare studier tar upp både funktions och prestandajämförelser där denna studie ämnar att brygga gapet som finns bland prestandajämförelser. Problem: Det saknas prestandajämförelser vid objektgenering i Unreal Engine och Unity Forskningsfråga Vilka skillnader i prestanda finns mellan Unity och Unreal Engine vid tester riktade mot objektgenerering? Metod: Metoden som används är ett kvantitativt experiment där testet som utförs är ett scenario som utvecklas så identiskt som möjligt i båda spelmotorerna. Scenariot består av varierande antal objekt som skapas där datan som samlas in är tiden för objektgenereringen. Resultat: Resultatet analyseras genom flera icke-parametriska tester där det framgår att Unity genomgående presterar mycket bättre än Unreal Engine oavsett hårdvarukonfiguration. Diskussion: Prestandaskillnaderna kan delvis förklaras av användningen av Blueprints i Unreal Engine. Trots detta ger studiens resultat en jämförbar och replikerbar analys av spelmotorernas prestanda när det kommer till objektgenerering. Studien pekar också på vikten av rättvisa jämförelser, eftersom spelmotorernas olika sätt att hantera resurser kan påverka resultaten. Framtida studier föreslås undersöka fler spelgenrer, använda fler maskinkonfigurationer och testa spelmotorerna i kontrollerade miljöer.Introduction This study compares two of the most commonly used game engines, Unity and Unreal Engine, with the aim of determining how they perform relative to each other in object generation. Previous studies have addressed both functional and performance comparisons, with this study aiming to bridge the gap in performance comparisons. Problem There is a lack of performance comparisons for object generation in Unreal Engine and Unity. Research Question What are the performance differences in the speed at which Unity and Unreal Engine can generate a number of objects? Method The method used is a quantitative experiment where the test performed is a scenario developed as identically as possible in both game engines. The scenario consists of varying numbers of objects being created, with the data collected being the time taken for object generation. Results The results are presented in diagrams and analyzed through a nonparametric test, where it is clear that Unity consistently performs much better than Unreal Engine. Discussion The performance differences can partly be explained by the use of Blueprints in Unreal Engine. Despite this, the study’s results provide a comparable and replicable analysis of the game engines’ performance in terms of object generation. The study also highlights the importance of fair comparisons, as the engines’ different methods of handling resources can impact the results. Future studies are suggested to explore additional game genres, use more machine configurations, and test the game engines in controlled environments
Phishing in the Workplace: Organizational Practices, Culture and Phishing Vulnerability
No full textIn today's digitally dependent workplaces, phishing attacks are a persistent and damaging cybersecurity threat. Phishing involves fraudulent attempts to obtain sensitive information, such as login credentials or financial details, by acting as a trustworthy entity, often through email. These attacks exploit human vulnerabilities through deceptive tactics, often resulting in significant financial and reputational damage to organizations. Despite advances in technical defenses, the role of organizational practices such as leadership, communication, structure, and culture in influencing phishing susceptibility among employees remains underexplored. The research question for the study is: “How do the organizational practices structure, leadership, communication and culture affect employees' vulnerability and susceptibility to phishing attacks?”. Using a qualitative case study approach focusing on Söderberg & Partners, a prominent Swedish financial services organization, the research is conducted using data collected through semi-structured interviews with representative informants. The data is analyzed using thematic analysis to uncover patterns and insights into organizational practices and their impact on phishing defenses. The findings indicated that a flat organizational structure and a supportive communication culture facilitate information sharing and timely reporting of phishing incidents. Leadership that emphasizes awareness and security-conscious norms strengthens employee preparedness. However, gaps in personalized training and fear of repercussions for reporting phishing attempts persist, highlighting areas for improvement. This research underscores the interrelated role of organizational practices in mitigating phishing risk, and provides practical insights for developing a resilient cybersecurity culture in organizations
Conceptualizing adolescent substance use : A multi-substance and multi-method study
No full textThis dissertation focuses on key conceptualizations of adolescent substance use that are used in science, policy, and prevention to calibrate societal responses to related problems. It examines how such conceptualizations and other ways of providing meaning to both legal and illegal substance use function in explaining who these users are and how their use develops over time. The ambition is also to study how adolescents, upon reaching young adulthood, provide meaning to substance use and to what extent dominant conceptualizations are reflected in their lay discourse. The conceptualizations addressed include the Risk Factor Model, the Normalization Thesis, the Gateway Theory, and the discourse of neoliberalism. The dissertation consists of four studies that are based on quantitative survey data and qualitative interview data from the Futura01 cohort; a representative sample from the normal population of adolescents. The data cover three time points: survey data from 2017 (participants’ age: 15/16) and 2019 (age: 17/18), and interview data from 2022-23 (age: 21/22). Study I use regression analysis to explore the association between risk factors and substance use at two time points. Study II employs latent transition analysis to identify clusters of adolescent substance users and how adolescents transition between these clusters over time. Study III uses the Logics of Critical Explanation framework to examine how substance use, risk factors, and future prospects are understood by young adults in qualitative interviews. Finally, Study IV uses a narrative approach to explore how young adults understand their own transition out of adolescent substance use and into responsible adulthood. The studies jointly found support in the Swedish normal population for some of the above-mentioned conceptualizations, while others fell short. The Risk Factor Model and the Normalization Thesis could partially explain adolescent substance use. For instance, some micro-level risk factors were stable predictors of substance use as they could predict use of both legal and illegal substances, both in 9th and 11th grade. Others could predict use of certain substances or use at specific time points, or fail to predict at all. However, this dissertation found little support for the Gateway Theory. Although these conceptualizations are primarily utilized in quantitative research, they were prominently reflected in the participants’ lay discourse, as expressed during the research interviews. Furthermore, the participants primarily conceptualized substance use through neoliberal ideals such as individualism, moderation, and health. The use of both legal and illegal substances was understood as something enjoyable and, in part, as a practice associated with adolescence. However, participants believed that substances should not be used to the extent that they would jeopardize a successful transition into adulthood. For them, this stance was associated with a process of maturing out of substance use during their early 20s, as well as maintaining a permanent state of vigilance if they choose to try or use legal or illegal substances after this period in life. In correspondence with the setup of substance use prevention and policy in Sweden, the participants seemed to favor conceptualizations whose point of departure was individualism. The dissertation closes with a discussion about whether this far-reaching focus on substance use as individual choice risks obscuring alternative conceptualizations and societal responses that highlight the influence of structural factors on deviant behavior such as adolescent substance use
Molecular Transients in Photoactive Heterocyclic Systems
No full textThe journey from light-induced excitation of a photoactive molecule to the formation of a stable photoproduct unfolds through a sequence of complex transformations within the molecular system. These transformations are governed by ultrafast processes and short-lived intermediates or transient species, which are crucial to the photoprocess. Studying these intermediates is vital not only for understanding the fundamental light-matter interactions that underlie natural optical phenomena but also for enabling the design of photochemical and photophysical reactions across diverse fields of application. Optical spectroscopic methods are commonly used to gather experimental evidence of these phenomena. Although these methods identify the intermediates based on their energy signatures, a proper characterization of the electronic structure remains elusive. This thesis delves into sophisticated quantum chemical frameworks, supported by multiple studies, to elucidate the mechanism and architecture involved in characterizing the short-lived molecular transients. The studies addressed in the thesis highlight the rich photochemistry of heterocyclic compounds through theoretical dynamical modeling and spectral simulations. In the first part, the non-adiabatic effects in photoexcited thiopyridone are explored. A collective theoretical and experimental investigation describes the molecular evolution during the ultrafast process and the observed variations across its constitutional isomers. The possibility of formation of a molecular excimer is also explored. The second part focuses on imidazole to simulate the electronic and structural changes that lead to proton transfer, with particular attention given to the local effects that influence the overall characteristics
Sculpting Galaxies & Orchestrating Mergers : Feedback-Driven Turbulence and Radiation Escape in Simulated Galaxies
No full textGalaxy formation is a continuous process that began only a few hundred million years after the Big Bang. As the first galaxies emerged and large populations of stars formed within them, their radiation ionised the surrounding gas. Before this epoch, the Universe was largely opaque to ionising radiation, and only a small fraction of light could traverse the intergalactic medium (IGM). These early galaxies were highly volatile, with bursts of star formation and disorganised gas motions driven, partially, by stellar feedback, close interactions, and mergers. Over time, galaxies evolved to host more orderly, rotating gas discs; however, the gas within these discs, the interstellar medium (ISM), remained highly turbulent. In fact, the ISM is supersonically turbulent, with gas motions exceeding the sound speed of the medium. This turbulence plays a key role in several processes related to galaxy evolution, including shaping the gas density distribution, regulating star formation, and enhancing gas mixing. The first papers of this thesis (Paper I and II) seek to answer what is driving this turbulence. We perform numerical simulations of isolated disc galaxies with masses similar to the Milky Way (MW), at two different epochs: present-day MW, characterised by quiescent gas motion and star formation, and a younger, gas-rich, and more turbulent MW. We investigate the relation between the star formation rate (SFR) and turbulence in galaxies (Paper I), and identify the difference between the diffuse ionised gas (DIG) phase and ionised gas embedded in molecular clouds, called H II regions (Paper II). We simulate these galaxies with and without stellar feedback, and conclude that feedback from stars plays a crucial role in driving the high turbulence in ionised gas (traced by Hα) found by observers. We also show that observational biases, such as beam smearing, can boost the observed turbulence by a factor of 2-3. Finally, we demonstrate that the majority of Hα emission originates from H II regions within the disc, but that the DIG phase is significantly more turbulent. The second part of this thesis (Paper III and IV) focuses on how galaxy mergers can trigger starbursts and enhance the escape of ionising radiation; particularly, Lyman Continuum (LyC) radiation from stars. Specifically, we simulate a merger between two disc galaxies to reproduce the Haro 11 galaxy merger, which is the closest known LyC leaker and a local analogue of galaxies in the early universe that ionised the IGM. In Paper III, we constrain the initial orbital conditions and match our simulation with several observed features of Haro 11; such as its single tidal tail, gas and stellar morphology, and overall kinematics. Thus, we show that our simulation can reproduce Haro 11, and that the characteristic properties of the galaxy can arise from a merger. In Paper IV, we demonstrate that the LyC escape fraction varies by 1–2 orders of magnitude across different sightlines. Moreover, we find that during each close passage between the two galaxies, the median LyC escape fraction rises by an order of magnitude, which we attribute to the spatial displacement of stars (the source of LyC) relative to the gas and the formation of ionised escape channels by stellar feedback. These findings suggest that mergers are an effective mechanism for facilitating the escape of ionising radiation, and may thus be a key process for reionising the Universe.Galaxbildning är en kontinuerlig process som inleddes endast några hundra miljoner år efter Big Bang. När de första galaxerna bildades och stora populationer av stjärnor uppstod inom dem, joniserade deras strålning den omgivande gasen. Före denna epok var universum till stor del ogenomskinligt för joniserande strålning, och endast en liten andel ljus kunde färdas genom det intergalaktiska mediet (IGM). Dessa tidiga galaxer var mycket instabila, med intensiva stjärnbildningsepisoder och oorganiserade gasrörelser, delvis drivna av stjärnfeedback, nära interaktioner och kollisioner. Med tiden utvecklades galaxerna till att hysa mer ordnade, roterande gaskivor; men gasen i dessa skivor, det interstellära mediet (ISM), förblev starkt turbulent. Faktum är att ISM är supersoniskt turbulent, med gasrörelser som överstiger ljudhastigheten i mediet. Denna turbulens spelar en nyckelroll i flera processer som är relaterade till galaxutveckling, inklusive att forma gasens täthetsfördelning, reglera stjärnbildning och främja gasblandning. De första delarna av denna avhandling (Artikel I och II) syftar till att besvara frågan om vad som driver denna turbulens. Vi utför numeriska simuleringar av isolerade diskgalaxer med massor liknande Vintergatans (MW) vid två olika epoker: nutida MW, som kännetecknas av lugnare gasrörelser och stjärnbildning, samt en yngre, gasrik och mer turbulent MW. Vi undersöker relationen mellan stjärnbildningshastigheten (SFR) och turbulens i galaxer (Artikel I), samt identifierar skillnaden mellan den diffusa joniserade gasfasen (DIG) och den joniserade gasen som är inbäddad i molekylmoln, så kallade H II-områden (Artikel II). Vi simulerar dessa galaxer både med och utan stjärnfeedback och drar slutsatsen att stjärnfeedback spelar en avgörande roll i att driva den höga turbulens i joniserad gas (spårad med Hα) som observeras. Vi visar också att observationsmässiga effekter, såsom "beam smearing", kan förstärka den observerade turbulensen med en faktor 2–3. Slutligen visar vi att huvuddelen av Hα-emissionen kommer från H II-områden inom galaxskivan, men att DIG-fasen är betydligt mer turbulent. Den andra delen av denna avhandling (Artikel III och IV) fokuserar på hur galaxkollisioner kan utlösa stjärnbildningsepisoder och öka andelen joniserande strålning som kan undkomma; särskilt Lyman Continuum (LyC) strålning från stjärnor. Specifikt simulerar vi en kollision mellan två diskgalaxer för att reproducera Haro 11-galaxen, som är den närmaste kända LyC-läckande galaxen och en lokal analog till de galaxer som i det tidiga universum bidrog till rejoniseringen av IGM. I Artikel III fastställer vi de inledande parameterarna för galaxernas banor och matchar vår simulering med flera observerade egenskaper hos Haro 11, såsom dess ensamma tidvattenssvans, gas- och stjärnmorfologi samt övergripande kinematik. Därmed visar vi att vår simulering kan reproducera Haro 11 och att galaxens karakteristiska egenskaper kan uppstå genom en kollision. I Artikel IV visar vi att fraktionen av LyC-utsläpp varierar med 1–2 storleksordningar beroende på siktlinje. Dessutom finner vi att vid varje nära passage mellan de två galaxerna ökar den medianta fraktionen av LyC-flykt med en storleksordning, vilket vi tillskriver en rumslig separation mellan stjärnorna (källan till LyC) och gasen, samt bildandet av joniserade flyktkanaler genom stjärnfeedback. Dessa resultat tyder på att kollisioner är en effektiv mekanism för att underlätta undkommande joniserande strålning och därmed kan ha varit en nyckelprocess för universums rejonisering