Publikationer från Karlstads Universitet
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Strongly Coupled Two-scale System with Nonlinear Dispersion : Weak Solvability and Numerical Simulation
No full textWe investigate a two-scale system featuring an upscaled parabolic dispersion–reaction equation intimately linkedto a family of elliptic cell problems. The system is strongly coupled through a dispersion tensor, which depends on thesolutions to the cell problems, and via the cell problems themselves, where the solution of the parabolic problem interactsnonlinearly with the drift term. This particular mathematical structure is motivated by a rigorously derived upscaledreaction–diffusion–convection model that describes the evolution of a population of interacting particles pushed by a largedrift through an array of periodically placed obstacles (i.e., through a regular porous medium). We prove the existence anduniqueness of weak solutions to our system by means of an iterative scheme, where particular care is needed to ensure theuniform positivity of the dispersion tensor. Additionally, we use finite element-based approximations for the same iterationscheme to perform multiple simulation studies. Finally, we highlight how the choice of micro-geometry (building the regularporous medium) and of the nonlinear drift coupling affects the macroscopic dispersion of particles. This paper was included as a manuscript in the doctoral thesis entitled "Scaling effects and homogenization of reaction-diffusion problems with nonlinear drift" KUS 2024:7</p
Exclusionary states in older age and their temporary effects on cognitive decline
No full textBackground Exclusion from social relations (ESR) describes severe states of social isolation in older age that maybe associated with poorer cognitive outcomes. Previous studies on cognitive aging provide mixed evidence for theeffects of social isolation and loneliness in shaping cognitive outcomes among older adults. In addition, the jointconsideration of social isolation and loneliness remains rarely used in the empirical examination of cognitive aging,whereas an exclusionary perspective is missing.Methods Using a sample (N=7,830) from the Survey of Health, Ageing, and Retirement in Europe (SHARE), this studyexamined the cross-sectional and longitudinal effects of three ESR states in older age (ESR and lonely, ESR but notlonely, not ESR but lonely) on episodic memory. Living alone or without a partner, being active in the labor market, andsocial participation were also included as exclusionary states in linear mixed models with health, demographics, andsocioeconomic factors as covariates.Results Cross-sectionally, ESR states in older age are associated with worse episodic memory independent ofloneliness. There was no evidence for longitudinal effects between ESR states at baseline and episodic memory slopesover time.Conclusions It was concluded that the negative effects of loneliness-typified ESR states on cognitive aging may betemporary and reversible, as a function of older adults’ transition in-and-out of these exclusionary states.Following publication of the article, it was brought tothe journal’s attention that the given and family nameof the author had been erroneously swapped. The order of the author’s name has since been corrected, and the corrected name may be seen in the author list in the file 'correction'. </p
Critical care nurses’ health and their description of a healthy and sustainable work environment in intensive care units in Sweden : A cross-sectional study
No full textIntensive care units are stressful environments and can bring negative psychological outcomes among critical care nurses. The aim of the present study is to describe critical care nurses’ characteristics and perceptions of health in relation to sex, and also provide their description of a healthy and sustainable work environment in intensive care units using a person-centred practice framework. A cross-sectional design was employed with 136 participants who responded to a questionnaire. Descriptive statistics and qualitative content analysis were used. Regardless of sex, critical care nurses perceived their current health to be significantly lower than their health before the COVID-19 pandemic. They described effective staff relationships and a supportive organization as being essential for a healthy and sustainable work environment. Critical care nurses have recovered to their perceived pre-pandemic health to some degree. Well-functioning teams and a supportive organizational system might nurture a healthy and sustainable work environment.
Datafying citizens : Third-party trackers and data-as-payment in government infrastructure
No full textScandinavians are among the most datafied citizens in the world. With its digitalised welfare states, Danish, Norwegian, and Swedish e-governance infrastructures collect massive amounts of data about citizens as they search for jobs, apply for building permits, and check school calendars. In this article, we analyse the use of third-party trackers (n = 2,761) on Scandinavian municipal websites (n = 745) between 2007-2023. Mobilising the theoretical framework of universalism, our aim is to understand what kind of cost data tracking constitutes for users of digital government services. Results show that Scandinavian municipal websites are dominated by commercial trackers harvesting citizen data for advertising purposes, particularly those provided by Alphabet and Meta. We conclude that commercial user-tracking on Scandinavian municipal websites does not conform to the principle of universality, proposing 1) that governments ensure transparency of the cost incurred by these websites' data tracking, and 2) that they ban commercial tracking on municipal websites
Microstructural, mechanical, corrosion, and biological behavior of spark plasma sintered commercially pure zinc for biomedical applications
No full textThis study investigates the microstructural, mechanical, corrosion, and biological behaviors of spark plasma sintered (SPS) zinc (Zn) samples for biomedical applications. The findings reveal that SPS significantly refines the grain structure of pure Zn compared to the conventional casting method. The SPS process, conducted at a lower sintering temperature of 300 °C and a high uniaxial pressure of 50 MPa, produces fine and uniform equiaxed grains with an average size of 19 μm. The resulting Zn samples exhibit a calculated density of 7.1 g cc−1 due to complete densification. The sintering process disrupts the initial texture strength, and the uniform grain orientation achieved during SPS contributes to an isotropic microstructure, enhancing the mechanical properties. The compressive yield strength and ultimate strength of the SPS samples are 115 ± 4 MPa and 191 ± 6 MPa, respectively. The long-term biodegradation behavior of SPS Zn in simulated body fluid indicates controlled and gradual corrosion, supporting its potential for biodegradable implant applications, while potentiodynamic polarization analysis further confirms similar corrosion rates compared to cast Zn due to the formation of a stable corrosion product film. In vitro studies with MC3T3-E1 preosteoblast cells show healthy proliferation in culture media containing the degradation products of SPS Zn. Due to its unique microstructural, mechanical, and corrosion properties, along with its biocompatibility, SPS-processed Zn is a promising candidate for tissue engineering applications.
A novel FFT-based micromechanical modeling approach for the fracture behavior of a composite core in metal sandwich plates using a cohesive zone model
No full textHybrixTM sandwich plates (Lamera AB, Gothenburg, Sweden) with metal face sheets could replace standard metal plates in many lightweight applications. Their composite core, which is crucial for the structural performance and the fracture behavior of the whole plate, consists of polymer fibers and binder, and a large amount of porosity. In this work, a novel micromechanical modeling approach for the fracture behavior of the composite core is presented, which could allow for a faster and improved design process for novel configurations of the plates. The modeling approach involves a novel method for the generation of virtual models for the complex microstructure of the core and our recently developed theoretical framework of an FFT-based computational homogenization scheme for cohesive zones. Furthermore, the parameters of the elastic–plastic material model including a non-local, ductile damage model were identified using microindentation experiments and mode I tests (Double Cantilever Beam). The novel modeling approach, along with the FFT-based homogenization scheme for cohesive zones, was also experimentally validated using mode III tests (Split Cantilever Beam) and a corresponding Finite Element simulation.
Challenges in palliative care – the nurse's experiences
No full textBakgrund: cancer är en sjukdom som orsakas av en okontrollerad celldelning, vanligaste är bröstcancer, prostatacancer och lungcancer. I Sverige diagnostiseras omkring 60 000 personer per år. Patienten med cancer kan uppleva både psykiska, fysiska, sociala och existentiella behov där både patienten och närstående drabbas. Palliativ vård syftar till att symtomlindra och förbättra livskvalitén för patienten och närstående, där sjuksköterskan spelar en viktig roll under hela vården. Syfte: belysa sjuksköterskans erfarenhet av att ge palliativ vård till patienten med cancer i livet slutskede inom slutenvård. Metod: litteraturstudien bygger på Roséns fyra steg. Artiklarna har sökts i Cinahl, Medline och via två frisökningar där 10 artiklar inkluderades. Artiklarna har kvalitetsgranskats utifrån Forsberg och Wengströms granskningsprocess. Databearbetning har analyserats utifrån induktiv ansats och induktiv analys. Resultat: Sammanlagt identifierades fem teman varav två med två underteman: kommunikationens betydelse: kommunikation med patienter och kommunikation med närstående och stödets betydelse: stöd till patient och närstående och andligt stöd. Resterande tre teman var: teamsamverkan, klinisk kompetens och emotionell belastning. Slutsats: Litteraturstudien visar att sjuksköterskors erfarenheter av att ge palliativ vård till patienter med cancer i livets slutskede är komplext och känslomässigt krävande. Kommunikation, stöd, teamsamverkan, klinisk kompetens och emotionell belastning framkom som centrala faktorer. Sjuksköterskors kliniska kompetens är avgörande för att kunna ge god och säker vård, utbildning behövs för att utveckla denna kliniska kompetens
Hydrochoric Seed Dispersal of Riparian Plants Follows Hydrological Patterns Closer Than Geomorphic Variation
No full textWater is an important dispersal vector for seeds of riparian plants, but little is known on how this form of dispersal, called hydrochory, varies throughout seasons and through geomorphically different areas. Therefore, we trapped seeds in 25 x 25 Astroturf mats along a free-flowing boreal river for an entire year. Sites mirrored the full range of geomorphic variation in the area and traps were emptied before and after the annual peak flow. The traps collected 2,062 seeds before the spring flood and 16,157 during the spring flood. While most of the seeds were deposited in the summer-low water traps (from now on "water edge") before the spring flood, they were distributed more equally in the riparian traps (defined as the level 40 cm above the water edge; from now on "riparian zone") during the spring flood. We found 77 species in total, of which 71 were at least recorded during the spring flood. Species numbers were higher at the water edge than at the riparian zone before and during the spring flood. Only 6.6% of the seeds, from 26 species, were viable. Most viable seeds were found in the water edge traps and, during the spring flood, in the riparian zone traps. While species that are primarily dispersed by water were not the most abundant among the viable seeds, they were the most species-rich group. This means that hydrochory is an important dispersal mechanism for riparian vegetation and an important contributor to riparian plant diversity in free-flowing rivers, and that changes in flow regimes, such as by flow regulation, can affect riparian vegetation composition
Micro-CT analysis of creased and folded multilayer cardboard
No full textMicro-CT analysis of experimentally creased and folded multilayer cardboards reveals insights into how the material deformation due to the creasing and folding process of cardboard impact the material concerning delaminations and position of broke particles. Delaminations were found in various locations and varied in size from just under a tenth of a millimeter to up to four times the thickness of the cardboard. The particles varied in size, ranging from a few micrometers to slightly larger than the cardboard thickness. Characteristic dimensions for the creased and folded cardboard were measured for selected cross sections. The differences in characteristic dimensions for the cross sections among the samples were typically a few hundredths of a millimeter. There are differences between cross-sections that are a few hundredths of a millimeter apart
Hypnagogia, psychedelics, and sensory deprivation : the mythic structure of dream-like experiences
No full textIntroduction Dream-like and psychedelic experiences often display internally illogical structures. Recent theories propose that these experiences function as "spontaneous offline simulations" related to specific brain processes. This study investigates whether such perceived illogicality reflects a distinct, premodern mode of cognition-commonly referred to as "mythic" cognition-rather than a cognitive deficit.Methods Thirty-one participants underwent four 90-minute flotation REST (Restricted Environmental Stimulation Technique) sessions designed to induce altered, dream-like states. After each session, participants completed the Phenomenology of Consciousness Inventory (PCI) and additional questions targeting features associated with mythic cognition.Results Participants showed significant phenomenological shifts toward experiences characteristic of mythic cognition. Specifically, their altered states during flotation exhibited ontological parallels with mythic conceptions of space, time, and substance.Discussion The findings support the hypothesis that the perceived illogicality in altered states arises from a distinct cognitive framework rather than from deficits