Publikationer från Uppsala Universitet
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Optimal choice of closest approach distance for a comet flyby : Application to the Comet Interceptor mission
No full textA comet flyby, like the one planned for the Comet Interceptor mission, takes place under conditions that remain largely unknown up to the moment of encounter. A detailed trajectory design phase, which includes verification of the technical limitations implied by the flyby geometry, precedes target comet selection. Thus the flyby velocity and the solar zenith angle at closest approach are known in advance. Solar irradiance and the neutral gas expansion speed can be estimated reasonably well. However, the comet outgassing rate, the dust production rate, and the solar wind conditions are only known within broader uncertainty margins. The present paper aims to optimally choose the one degree of freedom that is available for tuning the flyby conditions: the distance of closest approach. This choice is based on a simplified formalism that expresses, on one hand, the science return to be expected as a function of the closest approach distance, and, on the other hand, the risks implied by a close approach. This is done by performing Monte Carlo simulations over a large sample of possible comet flyby configurations, based on the expected probability distributions of the gas and dust production rates and the solar wind conditions, for different closest approach distances. For small flyby distances, a spacecraft has the opportunity to study the nucleus, the neutral gas coma, and the induced magnetosphere from up close, benefiting the science return. There is a trade-off to be made against the cometary dust collision risk, which becomes larger close to the nucleus. This trade-off is illustrated for the case of the Comet Interceptor main spacecraft and the two probes it plans to release. The change of the optimal flyby distance with gas and dust production rate, solar EUV flux, and flyby speed is discussed
State of the Science on Assessing Developmental Neurotoxicity Using New Approach Methods
No full textThe workshop titled State of the Science on Assessing Developmental Neurotoxicity Using New Approach Methods was co-organized by University of Maryland’s Joint Institute for Food Safety and Applied Nutrition (JIFSAN) and the U.S. Food and Drug Administration’s (FDA) Center for Food Safety and Applied Nutrition (CFSAN; now called the Human Foods Program), and was hosted by FDA in College Park, MD on November 14-15, 2023. This event convened experts from international organizations, governmental agencies, industry, and academia to explore the transition from traditional in vivo tests to innovative new approach methods (NAMs) in developmental neurotoxicity (DNT) testing. The discussions emphasized the heightened vulnerability of the developing human brain to toxic exposures and the potential of NAMs to provide more ethical, economical, and scientifically robust alternatives to traditional testing. Various NAMs for DNT were discussed, including in silico, in chemico, in vitro, non-mammalian whole organisms, and novel mammalian approaches. In addition to progress in the field, the workshop discussed ongoing challenges such as expectations to perfectly replicate the complex biology of human neurodevelopment and integration of DNT NAMs into regulatory frameworks. Presentations and panel discussions provided a comprehensive overview of the state of the science, assessed the capabilities and limitations of current DNT NAMs, and outlined critical next steps in advancing the field of DNT testing
Low rate of rescue epidural analgesia after open colorectal surgery with intrathecal morphine : a retrospective cohort study
No full textPurposeThe use of intrathecal morphine in open colorectal surgery has been limited despite being a promising analgesic alternative used in other types of open abdominal surgery. Intrathecal morphine has a higher success rate than thoracic epidural analgesia, the current standard method of analgesia in open colorectal surgery. Intrathecal morphine is occasionally used in open colorectal surgery when thoracic epidural analgesia placement fails and in instances when patients receive intrathecal morphine for a planned laparoscopic surgical procedure which is converted to laparotomy intraoperatively. This retrospective single-centre cohort study aimed to evaluate outcomes after intrathecal morphine in patients undergoing open colorectal surgery.MethodsAll patients who received intrathecal morphine before open colorectal surgery at a secondary hospital in Sweden between 2016 and 2020 were included. Routinely collected data from the Swedish PeriOperative Registry and patients' medical records were reviewed, and data regarding postoperative outcomes including the incidence of postoperative rescue thoracic epidural analgesia and adverse events were extracted.ResultsIn total, 108 patients were included with a median age of 74 years. Four patients (4%) received rescue thoracic epidural analgesia postoperatively, and the median hospital length of stay was 8 days. The median intrathecal morphine dose was 200 mu g. Respiratory complications occurred in two patients (2%).ConclusionThe incidence of rescue thoracic epidural analgesia after intrathecal morphine in open colorectal surgery was low, and there were few adverse events. The results suggest that intrathecal morphine could be a viable alternative for postoperative pain management in open colorectal surgery
En möjlighet för alla:- En kvantitativ enkät om hur förskollärare arbetar med barn i behov av särskilt stöd och inkludering
No full textStudien undersöker hur kan förskollärare veta vilka barn som är i behov av särskilt stöd och hur de arbetar för att inkludera barn som är i behov av särskilt stöd i förskolans verksamhet. Fokuset låg på förskollärarnas erfarenheter, olika strategier och vilka olika utmaningar som dyker upp i förskollärarnas arbete. Själva syftet gick ut på att fördjupa förståelsen hur förskollärare skapar en inkluderande miljö och hur de kan ge stöd till de barn som är i behov av särskilt stöd. Centrala begrepp är inkludering, barn i behov av särskilt stöd, förskolans arbetssätt, specialpedagogik och styrdokument diskuteras i relation till tidigare forskning och olika styrdokument. I studien så användes kvantitativ enkät med förskollärare och de var datainsamlingsmetoden. I resultatanalysen så lyftes fram vikten av resurser, vikten av stöd till de barn som behöver det samt tillgången till specialpedagogernas kompetens för att kunna ha möjlighet att skapa anpassad verksamhet som är inkluderande för alla barn. Dessutom så framkommer det att brist på resurser, inte tillräckligt med tid och andra faktorer i organisationen som gör att förskollärarna inte kan utföra ett arbete som inkluderar barnen på ett bra sätt.
Bethe Algebra using Pure Spinors
No full textWe propose a gl(r)-covariant parameterisation of Bethe algebra appearing in so(2r) integrable models, demonstrate its geometric origin from a fused flag, and use it to compute the spectrum of periodic rational spin chains, for various choices of the rank r and Drinfeld polynomials
Identifiera flaskhals och optimera flödet i produktionslinje
No full textThis research forms the basis of an investigation regarding the flow efficiency at Haldex in Landskrona; it was conducted in the spring of 2024. The purpose of the study is to investigate the possibility of increasing the capacity by identifying any bottlenecks and unnecessary processes and generating proposals to improve the production line. Theories support the research in order to bring a deeper picture of how bottlenecks affect the production and what methods can be used to optimize the production flow. The ability to generate improvements and suggestions to enhance the production line at the company. The data collection was conducted through quantitative and qualitative methods. The required processing times were measured at all stations in the production line, and it showed that at station 4, where the first components were installed in the brake, was a limiting part of production as the station had the highest processing time. With the help of an extra operator from one station to the bottlenecks that are found in production, this could result in reducing the processing time for station 4 by 20 seconds per unit. As a result, a number of proposals to improve the production line have been reported to the company which can be used to avoid the wasted time, an example Machine 6, wastes 30 seconds where one can eliminate the waitingtime
Arbetssätt i matematikundervisningen : En kvalitativ studie om grundskollärares val av arbetssätt i matematikundervisningen och de bakomliggande faktorerna i årskurs 2
No full textSyftet med studien är att bidra med kunskap om de arbetssätt som grundskollärare i årskurs 2 använder i matematikundervisningen, samt de bakomliggande faktorerna till val av arbetssätt. Denna studie gjordes eftersom vi anser att det inte finns tillräckligt med tidigare forskning om vilka arbetssätt lärare i årskurs 2 använder sig av samt de bakomliggande faktorerna till valen av arbetssätt. Tidigare forskning har haft fokus på vad det finns för arbetssätt generellt i matematikundervisningen och dess påverkan på undervisningen. Detta leder till att det finns en kunskapslucka om hur dessa arbetssätt tillämpas och vad som motiverar lärarna att välja dem i årskurs 2. I studien gjordes semistrukturerade intervjuer och analyserades genom en tematisk analysmetod. Den teoretiska utgångspunkten som användes i studien var den didaktiska triangeln. Resultaten i studien visar att lärarna använder sig av gemensamma och olika arbetssätt i matematikundervisningen i årskurs 2. I studien kom vi fram till att samtliga lärare använder dessa gemensamma arbetssätt: Genomgång, Konkret material, Samtala om matematik och Matematikboken. I studien framkommer det att samtliga lärare anser att det finns flera olika faktorer som påverkar deras val av arbetssätt i matematikundervisningen. Lärarna lyfter fram vikten av tid, reflektion och att undervisningen ska kännas verklig för eleverna. Dessutom betonar lärarna vikten av att eleverna ska vara delaktiga och förstå syftet med undervisningen i matematikämnet
Corpus of the Balochi Dialects : Sistani
No full textThe aim of the present study is to compile a digitally annotated corpus of oral narratives from the Sistani Balochi dialect. The annotated oral texts are drawn from two genres: folktales and biographical narratives. These stories were recorded during several field trips to Iran. The first section of the book provides an overview of the geographical distribution of Sistani Balochi speakers, situating the Sistani Balochi dialect within the broader Balochi language. This is followed by a brief discussion of the data collected. Of particular note is the fact that the storytellers are typically bilingual or multilingual. The second section of the book presents four texts that have been interlinearized using the FLEx program. This book forms part of a series dedicated to the publication of oral texts from various Balochi dialects
Thickness of the stratigraphic record of Britain : How the fidelity of geological and fossil data is unrelated to rock quantity
No full textThe sedimentary-stratigraphic record is the principal repository of empirical historic evidence for evolution and deep time environments. However, the record has a temporal incompleteness and inconsistency to its extensive quantity, driven by the spatial heterogeneity of deposition and erosion. This is argued to bias intensive fossil records, with correlations apparent between fossil diversity and mapped rock area from different intervals. However, mapped rock area is a poor proxy for strata accessible for fossil studies because most is concealed. Additionally, spatially diminutive older rocks commonly sample a greater stratigraphic transect per unit exposure area than widespread younger rocks because the tectonic forces that drive recycling additionally result in tilting. We calculate observable vertical stratigraphic thickness throughout geologic history for southern Britain and show that potential sample availability increases with age, in contrast to general models of rock survivorship. Using this subsample of the sedimentary-stratigraphic record as a calibration sample for the global record, we find no correlation between available stratigraphic thickness and palaeobiodiversity, except in flat-lying strata. We demonstrate instances where the first occurrences of fossil genera appear robust because there is high availability of suitable host rock pre-dating them. Our work suggests that preservation biases induced by variability in rock quantity have been significantly overstated and that local tectonic history renders different regions as stratigraphic hotspots for specific intervals, in which intensive high-veracity fossil records have exceptional value for elucidating global trends and timing in evolutionary history. The British non-marine Palaeozoic record is highlighted as such an example, with high-fidelity palynological records of plant evolution and ichnological records of animal terrestrialization
Personalized Privacy Amplification via Importance Sampling
No full textFor scalable machine learning on large data sets, subsampling a representative subset is a common approach for efficient model training. This is often achieved through importance sampling, whereby informative data points are sampled more frequently. In this paper, we examine the privacy properties of importance sampling, focusing on an individualized privacy analysis. We find that, in importance sampling, privacy is well aligned with utility but at odds with sample size. Based on this insight, we propose two approaches for constructing sampling distributions: one that optimizes the privacy-efficiency trade-off; and one based on a utility guarantee in the form of coresets. We evaluate both approaches empirically in terms of privacy, efficiency, and accuracy on the differentially private k-means problem. We observe that both approaches yield similar outcomes and consistently outperform uniform sampling across a wide range of data sets. Our code is available on GitHub