Publikationer från Umeå universitet
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Macroecological patterns of rodent population dynamics shaped by bioclimatic gradients
No full textLong-term studies of cyclic rodent populations have contributed fundamentally to the development of population ecology. Pioneering rodent studies have shown macroecological patterns of population dynamics in relation to latitude and have inspired similar studies in several other taxa. Nevertheless, such studies have not been able to disentangle the role of different environmental variables in shaping the macroecological patterns. We collected rodent time-series from 26 locations spanning 10 latitudinal degrees in the tundra biome of Fennoscandia and assessed how population dynamics characteristics of the most prevalent species varied with latitude and environmental variables. While we found no relationship between latitude and population cycle peak interval, other characteristics of population dynamics showed latitudinal patterns. The environmental predictor variables provided insight into causes of these patterns, as 1) increased proportion of optimal habitat in the landscape led to higher density amplitudes in all species and 2) mid-winter climate variability lowered the amplitude in Norwegian lemmings and grey-sided voles. These results indicate that biome-scale climate and landscape change can be expected to have profound impacts on rodent population cycles and that the macro-ecology of such functionally important tundra ecosystem characteristics is likely to be subjected to transient dynamics.First published online: 27 December 2024</p
Characterisation of heritable TP53-related cancer syndrome in Sweden : a nationwide study of genotype-phenotype correlations in 90 families
No full textWe aimed to describe the clinical characteristics of families with heritable TP53-related cancer (hTP53rc) syndrome in Sweden with class 4 and 5 germline TP53 variants (gTP53), and to evaluate the genotype-phenotype correlation. These results were also used to evaluate our previously published phenotype prediction model based on TP53 missense variants and their impact on protein conformation. 90 families with hTP53rc were initially identified in Sweden. After variant reclassification using the TP53-specific ACMG criteria, 83 families remained (176 carriers) to harbour a pathogenic (class 5) or likely pathogenic (class 4) variant in TP53. Of these, 112 carriers (64%) had a previous history of cancer, and 35 (31%) had developed more than one primary tumour. 16% of the families met the stricter criteria for Classic Li-Fraumeni syndrome, 45% the updated Chompret criteria, 35% for hereditary breast cancer (HBC), and the remaining 5% were classified as “Others”. We identified 42 different gTP53 variants of which 22 were missense. The most frequently observed variant was the missense c.542 G > A, p.R181H identified in 14/29 (48%) of HBC families. Fifteen of the 20 informative missense variants (75%) were phenotypically predicted correctly using our previously published in silico prediction model. The TP53 p.R181H was identified as a common Swedish variant predominantly associated with an HBC phenotype. Apart from this variant, there were no significant genotype-phenotype correlations. Therefore, due to phenotypic overlap it is still too early to stratify surveillance programme for different TP53-carriers
Improved outcomes after groin hernia surgery in Sweden between 1992 and 2021 : Swedish Hernia Register
No full textPURPOSE: Surgery for groin hernia is one of the most common operations in the world. Therefore, research concerning the outcomes of groin hernia surgery is extremely important both for the individual patient as well as for those providing the healthcare funding. The aim of this study is to evaluate the outcomes of hernia surgery in Sweden over a 30 year time period, from 1992 to 2021. METHODS: All groin hernia repairs in the Swedish Hernia Register between 1992 to 2021 were analyzed with emphasis on the surgical method, reoperation rate for recurrence and date of surgery, specifically 1992-2001, 2002-2011 and 2012-2021. By using personal identification numbers, a cumulative reoperation rate has been deduced for males and females separately. RESULTS: A total of 368,502 groin hernia operations identified in the Swedish Hernia Register between 1992 to 2021 were eligible for analysis. Since the register was begun, there have been significant changes in the choice of operative techniques, from suture repair in 1992 to open anterior mesh repair around the year 2000, until today, where an increasing proportion of hernias are repaired using laparo-endoscopic techniques. There has been a reduction in the reoperation rate for recurrence in both males and females, with the most pronounced improvement being seen in females. The laparo-endoscopic technique is associated with a reduced incidence of reoperation for recurrence in females. CONCLUSION: Groin hernia surgery in Sweden has undergone substantial changes over the past 30 years. Reoperation for recurrence has decreased significantly during recent years, especially in females
Mesoporous carbon derived from lignin sulfonate as a sustainable cathode for high-performance aluminium batteries
No full textThe development of sustainable and efficient energy storage systems is crucial for addressing the growing global energy demand. This study investigates the potential of mesoporous carbon derived from lignin sulfonate as a cathode material for aluminium batteries. Lignin sulfonate, a by-product of the paper industry, was used as a precursor to synthesize mesoporous carbon through a facile and eco-friendly activation process. The resulting carbon material exhibited a high specific surface area of ∼ 2259 m2/g and a well-defined balance of micro- and meso- porosity, making it a promising cathode material for high-performance aluminium batteries. Electrochemical characterization showed that the mesoporous carbon cathode delivered an impressive specific capacity of 91 mAh/g at 1.0 A/g current density even after 7000 cycles with excellent cycling stability. It delivered superior rate capabilities of 105, 89, 80, 72, 67, 63, 90, and 105 mAh/g at 0.1, 1.0, 2.0, 3.0, 4.0, 5.0, 1.0, and 0.1 A/g current rates, respectively. The use of lignin-sulfonate as a precursor to prepare mesoporous carbon opens up a new sustainable way for improving the electrochemical performance of carbon-based cathode materials for aluminium batteries
Stable and high-order accurate finite difference methods for the diffusive viscous wave equation
No full textThe diffusive viscous wave equation describes wave propagation in diffusive and viscous media. Examples include seismic waves traveling through the Earth's crust, taking into account of both the elastic properties of rocks and the dissipative effects due to internal friction and viscosity; acoustic waves propagating through biological tissues, where both elastic and viscous effects play a significant role. We propose a stable and high-order finite difference method for solving the governing equations. By designing the spatial discretization with the summation-by-parts property, we prove stability by deriving a discrete energy estimate. In addition, we derive error estimates for problems with constant coefficients using the normal mode analysis and for problems with variable coefficients using the energy method. Numerical examples are presented to demonstrate the stability and accuracy properties of the developed method
The lifelong learner’s compass : cultivating attitudes with self-reflection, openness, curiosity and motivation
No full textLifelong learning can be indispensable for the adaptation to continuously evolving labor markets and societal demands. In the current study, we examined psychological factors, notably aspects of personality (personality traits in the five-factor model and trait curiosity), self-reflection and motivation in relation to attitudes to lifelong learning. A specific aim was to examine the relative importance of these factors in their contribution to attitudes to lifelong learning. The study was carried out by use of a digital survey and included 717 adults (Mage = 47.93) within working life. The results showed that self-reflection and trait curiosity were the strongest predictors of attitudes to lifelong learning but work intrinsic motivation and openness to experience (a personality trait in the five-factor model) also contributed with unique explanatory power, although to a lesser degree. The results can inform individualized accessibility strategies for lifelong learning
FOOD INTRODUCTION IN THE FIRST YEAR OF LIFE : Results from dietary questionnaire in the NorthPop study
No full textBakgrund Under barnets två första levnadsår befinner sig barnet i en sensitiv period där smakinlärning och upprepad exponering kan ligga till grund för hälsosamma matvanor. Livsmedel kan introduceras i pyttesmå smakportioner till intresserade barn som utökas i mängd med den stigande åldern för att tillgodose barnets tillväxt och utveckling. Introduktion av livsmedel med olika smaker, texturer och näringsinnehåll samt allergena livsmedel bör introduceras under barnets första levnadsår. Livsmedelsintroduktion har tidigare studerats i Sverige men introduktion och matvanor förändras i takt med samhällsutvecklingen och bör därav studeras kontinuerligt. Genom den populationsbaserade NorthPop studien kan matintroduktionen undersökas hos små barn. Syfte Att undersöka vilka livsmedel som introduceras under barns första levnadsår. Metod En kvantitativ metod användes baserat på insamlade webbaserade kostfrågeformulären vid nio och 18 månaders ålder för 4915 barn från NorthPop under åren 2016–2023 i Västerbottens län. Data redovisades deskriptivt och skillnader mellan grupper analyserades med hjälp av Mann-Whitney U-test. Resultat Introduktion av livsmedel skedde i alla åldersintervall, men som mest i åldersintervallet 4–6 månader. Högst introducerade livsmedel var frukt/bär, färdig-/pulvergröt, potatis och grönsaker/rotsaker i åldersintervallet 0–3 månader (2,3–6,2%) respektive 4–6 månader (86,3–90,3%). I åldersintervallet 7–9 månader var naturell fil/yoghurt, ägg och ris (33,7 - 36,4%) som högst introducerat. Lätt- & mellanmjölk, söta kex, kakor eller bullar och hårt bröd introducerades som högst i åldersintervallet 10–12 månader (14,8–18,3%). Lägst introduktion skedde av paranötter (4,2%), sojadryck (7,7%), sojagurt (8,9%) och godis eller liknande sötsaker (10,5%). Det var ingen skillnad i introduktion av potatis, ris, fisk och grönsaker/rotfrukter mellan flickor och pojkar eller mellan barn med syskon och barn utan syskon. Slutsats En stor del av de efterfrågade livsmedel introducerades mellan fyra och nio månaders ålder. Potatis, grönsaker/rotfrukter, pasta och frukt/bär var vanligaste att introducera under det första levnadsåret. Introduktion av livsmedel påverkades inte av kön eller syskon vilket ansågs positivt. Större delen av vårt resultat överensstämmer med Livsmedelverkets råd och rekommendationer avseende livsmedelsintroduktion.
Radon–Nikodym Theorem with Implications in Probability Theory
No full textThis essay focuses on the Radon-Nikodym Theorem, a cornerstone result in measure theory that relates two measures defined on the same measurable space when one is absolutely continuous with respect to the other. To understand the behaviour of the Radon-Nikodym Theorem, we define an integral with respect to an arbitrary measure space, develop essential concepts in measure theory, and present critical results such as the Monotone Convergence Theorem. An essential application of the Radon-Nikodym Theorem is in probability theory, where it provides a rigorous foundation for defining conditional probability and expectation.Denna uppsats fokuserar på Radon-Nikodyms sats, ett grundläggande resultat inom måttteori som relaterar två mått definierade på samma mätbara rum när det ena är absolut kontinuerligt med avseende på det andra. För att förstå beteendet hos Radon-Nikodyms sats definieras en integral med avseende på ett godtyckligt mätrum, och grundläggande begrepp inom måttteori utvecklas. Viktiga resultat, såsom den monotona konvergenssatsen, presenteras. En viktig tillämpning av Radon-Nikodyms sats finns inom sannolikhetsteorin, där den ger en rigorös grund för att definiera betingad sannolikhet och väntevärde
Livets tunna väggar : En ekokritisk analys av gränser i De Osynliga, Väggen, och Sommarboken
No full textThis essay will explore how literary characters inhabit circumscribed and confined spaces in three novels: Marlen Haushofers, The Wall, Tove Janssons, The Summer Book, and Roy Jacobsens, The Unseen. Through the use of ecocritical theory and Gaston Bachelard’s The Poetics of Space, the essay will examine the border between house and exterior landscape, between human and non-human. Seeing as The Summer Book as well as The Unseen take place on islands in the archipelago the essay will make use of island-literature studies. Since the chosen material is extensive, the analysis will look at certain key aspects of the novels that illustrate how the characters dwell, such as; the function of borders and the role of the intruder, the anthropomorphic portrayal of domestic animals, the relationship between identity and place as well as the depiction of time.