Publikationer från Uppsala Universitet
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Chemical characterization of C31 sterols from sponges and Neoproterozoic fossil sterane counterparts
No full textPutative metazoan body fossils from the Precambrian are curiously lacking morphological characteristics that link them unambiguously to extant animal phyla, including sponges. Chemical fossils such as the rare C30 hydrocarbons 24-iso-propylcholestane (24-ipc) and 26-methylstigmastane (26-mes), however, have been proposed as evidence for the Neoproterozoic emergence of the Demospongiae (Porifera) due to their prevalence in rocks of this age and the occurrence of their sterol precursors in contemporary demosponges. However, there are alternative hypotheses which posit that diagenetic alteration products of algal sterols, or those from Rhizaria or other protists, account for the enigmatic steroid distributions observed in these ancient sedimentary rocks. Here, we report additional support for the Neoproterozoic rise of demosponges through the chemical characterization of two previously unrecognized C31 hydrocarbons—24-n-butylcholestane (24-nbc) and 24-sec-butylcholestane (24-secbc). Precursor C31 sterols from contemporary demosponges, as well as a suite of synthesized C31 sterol standards were reduced to their sterane counterparts. Gas chromatography-tandem mass spectrometry analysis and collisionally activated dissociation mass spectra confirmed the presence of 24-nbc and 24-secbc in well-preserved early Ediacaran rocks, and the coelution of these compounds with synthetic standards enhances the robustness of these findings. Co-occurrence of abundant 24-ipc and 24-secbc was found for numerous Neoproterozoic-Cambrian rock/oil samples, closely mimicking the abundance patterns and high structural selectivity of major C30 and C31 sterols detected in numerous species of modern demosponges. These findings support the hypothesized first emergence of sponges during the Neoproterozoic Era
Velocity-space tomography of MeV-range fast-ion distributions in JET using wave-particle interaction priors
No full textThe fast-ion distribution function in fusion plasmas can only be measured indirectly by solving an ill-posed inverse problem. The inversion being ill-posed necessitates regularisation of the problem to ensure that the reconstruction of the fast-ion distribution function depends smoothly on the measurements obtained by fast-ion diagnostics. In turn, the resulting reconstruction depends on the choice of regularisation, and it is therefore beneficial to choose a physics-informed prior as regularisation scheme. In this work, we reconstruct the high-energy tail in the MeV-range of the fast-deuterium distribution in JET discharges heated by waves in the ion cyclotron range of frequencies (ICRF) using neutron and gamma-ray emission spectroscopy. We do this by applying a physics-informed prior based on collision physics and a newly formulated ICRF-physics prior, and we compare these results with numerical simulations and inversions based on a standard Tikhonov regularisation scheme. Our findings suggest that the physics-informed regularisation scheme including the ICRF prior improves the reconstructions compared with standard Tikhonov regularisation. Finally, it is shown that constraining the reconstruction to have negative gradients in the directions of phase space dictated by ICRF physics results in a reconstruction that well resembles expectations based on ICRF physics theory and numerical simulations
Distribution and phylogeny of the Undecim Cluster, a conserved eleven-gene island in endosymbiont Wolbachia
No full textSuperstorm-driven electron temperature (Te) anomalies in the topside low-latitude ionosphere : role of the equatorial ionization anomaly (EIA)
No full textWe present the first near-simultaneous observations of the altitudinal and latitudinal evolution of electron temperature (Te) in the topside ionosphere during a superstorm, using Swarm and DMSP data. During the 10-11 May storm, a strong prompt penetration electric field (PPEF) induced a superfountain effect, intensifying the Equatorial Ionization Anomaly (EIA) crests and shifting them to mid-latitudes. This led to significant increases in plasma density (Ne) at Swarm A (474 km) and DMSP (840 km) altitudes. At Swarm altitudes, Te increased by 1500 K within the EIA trough, while at DMSP altitudes, Te decreased by 1000 K in the EIA crests. Enhancement in the Te at Swarm altitudes results from reduced electron-ion cooling from rapid Ne removal via upward EXB drift. Meanwhile, the elevated Ne at DMSP altitudes likely reduced Te locally while enhancing heat conduction along magnetic field lines to Swarm altitudes. These novel observations highlight the crucial role of the EIA in regulating low-latitude Te, leading to a reversal in the topside ionospheric temperature structure during the evening-sector superstorm
Evidence of different grey matter volume patterns in men and women who stutter - An explorative structural MRI study
No full textDevelopmental stuttering is a disorder with a high degree of heterogeneity, both behaviourally and neurologically. Research from different perspectives of stuttering indicates that sex is a potentially differentiating factor. In our study we explored if sex is related to variability of grey matter volume (GMV) patterns in adults with developmental stuttering. We used MRI to collect data on GMV from 24 righthanded adults who stutter (9 women and 15 men) and 29 righthanded fluent controls (10 women and 19 men). We analysed the following for 24 ROIs of the language system: 1) whole-group differences between the stuttering group and controls and 2) interaction between group (adults with stuttering versus controls) and sex. Our explorative results indicate that differences in grey matter volume between adults with stuttering and fluent adults are sexspecific for several areas involved in speech and language processing. We found an interaction between group and sex for the right BA45. The interaction indicates that men who stutter have larger GMV in this area compared to fluent men while women who stutter have smaller GMV compared to fluent women. Further, we found indications of sex-specific patterns in other areas of the bilateral inferior frontal cortex, but not the BA44, as well as in the cerebellum and the striatum
Altered effort and deconditioning are not valid explanations of myalgic encephalomyelitis/chronic fatigue syndrome
No full textEn väg mot målen eller en väg till frihet? : En kvalitativ studie om läs- och skrivförmåga inom montessori- och waldorfpedagogiken
No full textSedan genomförandet av friskolereformen år 1992 har antalet skolor med en alternativ pedagogik successivt ökat. Sedan år 2009 godkänner även skollagen att dessa pedagogiker använder egna styrdokument som komplement till nationella bestämmelser. Syftet med denna studie är därför att undersöka och synliggöra hur de alternativa pedagogiska inriktningarna montessori och waldorf vill främja elevers läs- och skrivförmåga genom egna kompletterande styrdokument och karakteristiska undervisningsmetoder. Studien använder en kvalitativ innehållsanalys av styrdokument, samt en diskursanalys av pedagogisk litteratur. Resultatet från studien pekar på att waldorfpedagogiken förespråkar undervisningsinnehåll och -metoder som främst fokuserar på elevens egna erfarenheter och konstnärligt skapande, medan montessoripedagogiken förespråkar tidig inlärning av kognitiva förmågor och en mer strukturerad undervisning med fokus på visuell organisering och processer. Även om det som förespråkas inom respektive inriktning har sina styrkor, så finns det också potentiella begränsningar. Waldorfpedagogikens fokus på kreativitet kan tänkas uppmuntra till personliga uttryck vilket gynnar elevernas läs- och skrivintresse, samtidigt riskerar man att försumma den lika viktiga explicita språkundervisningen. Montessoripedagogikens explicita struktur kan tänkas främja den tidiga läs- och skrivförmåga och medvetenhet kring skrivprocessen, men riskerar samtidigt att hämma elevernas kreativa självuttryck. Studien bidrar till en didaktisk insikt i vilken typ av språkundervisning de två alternativa pedagogikerna förespråkar, för vidare forskning hade det således varit intressant att undersöka hur detta tar sig uttryck i den faktiska undervisningen
Precision Assessment of Facial Asymmetry Using 3D Imaging and Artificial Intelligence
No full textObjectives: There is a growing interest among practitioners in employing artificial intelligence (AI) to enhance the precision and efficiency of diagnostic methods. The objective of this study is to assess the precision of an AI-based method for facial asymmetry assessment using 3D facial images. Methods: The study included 130 patients (84 female, 46 male), analyzing 3D facial images from the Vectra® M3 imaging system using both manual and AI-based methods. Seven bilateral facial landmarks were identified for manual analysis, calculating the asymmetry index for facial symmetry assessment. An AI-based program was developed to automate the identification of the same landmarks and calculate the asymmetry index. The reliability of the manual measurements was assessed using intraclass correlation coefficients (ICC) with 95% confidence intervals (CI). Precision of automated landmark identification was compared to the manual method. Results: The ICCs for the manual measurements demonstrated moderate to excellent reliability, both within raters (ICC = 0.62–0.99) and between raters (ICC = 0.72–0.96) each calculated with 95% CI. Agreement was observed between the manual and automated methods in calculating the asymmetry index for five landmarks. There was a statistically significant difference between the two methods in determining the asymmetry index for alare (median: 2.05 mm manual vs. 1.54 mm automated, p = 0.0056) and cheilion (median: 2.77 mm manual vs. 2.30 mm automated, p = 0.0081). Conclusions: The AI-based method provides efficient and comparable precision of facial asymmetry analysis using 3D images. The disagreement observed between the two methods can be addressed through further improvement and training of the automated software. This innovative approach opens doors to significant advancements in both research and clinical orthodontics
Sociodemographic factors influencing SARS-CoV-2 vaccination uptake in people with and without HIV : Insights from a Swedish Nationwide cohort
No full textCorrection in: “Sociodemographic factors influencing SARS-CoV-2 vaccination uptake in people with and without HIV: Insights from a Swedish Nationwide cohort” [Vaccine 62 (2025) 127580] Vaccine, Volume 67, 20 November 2025, Pages 127855 DOI: http://10.1016/j.vaccine.2025.127855 </p
Advances in Speculative Side Channel Mitigations and New Exploitations
No full textSpeculative execution optimizes processor performance by predicting the correct path of execution and executing instructions before it is legal to do so, introducing potential vulnerabilities when the prediction falls short and the program follows the wrong path of execution. While the processor recovers the architectural state, the microarchitectural state remains and can be exploited. In these vulnerabilities, that leverage the speculative side-channel (known as Spectre attacks), a secret is improperly accessed speculatively and then leaked by passing it to a transmitter instruction that leaves irreversible changes in the microarchitecture. Several proposed defenses try to close this security hole by prohibiting the propagation of speculatively loaded values, or by delaying the transmitter instructions (e.g., loads) from executing under speculation. Each of these proposed solutions leads to considerable performance degradation and, in certain instances, fails to entirely mitigate the security vulnerability. This thesis tries to address the challenges of performance and security by proposing three works on optimizing the performance of existing speculative side-channel defenses, namely Janus, ReCon, and Doppelganger Loads, and two works on addressing security vulnerabilities by demonstrating attack scenarios, namely DOIN!, and Reorder Buffer Contention. Regarding enhancing the performance of existing speculative mechanisms, Janus applies two of the simplest defense ideas in the same processor design and uses reinforcement learning to select the optimal performance-wise underlying defense mechanism on the fly, ReCon leverages non-speculative information leakage in an efficient manner to enable the execution of speculative load instructions that access non-secret values, and Doppelganger Loads employs an address predictor to unlock more speculative memory-level parallelism by predicting speculative load addresses in a secret-independent way. All the aforementioned techniques are able to recover a significant part of the lost performance introduced by speculative side-channel defenses. On the other hand, to expose security vulnerabilities, DOIN! attack exploits inclusive caches and the co-existence of instructions and data in last-level caches to create observable timing differences in the data cache, surpassing speculative defenses, and Reorder Buffer Contention adds secret-dependent contention to the reorder buffer pushing in or out, on demand, a transmitter instruction able to leak the value of the speculatively loaded secret