Denna studie undersöker betydelsen av sociala nätverk och rekreationsaktiviteter för välbefinnandet hos ett urval skandinaviska sjöfarare, med särskilt fokus på hur dessa aktiviteter påverkar deras psykosociala hälsa ombord på fartyg. Studien belyser sambandet mellan mental ohälsa och tillgängligheten till rekreationsmöjligheter, samt analyserar effekterna av internet och socialt stöd för att hantera isolering och stress. Genom en kvalitativ metodologi med semistrukturerade intervjuer och användning av Social Network Theory, analyseras dynamiken och interpersonella relationer ombord. Resultaten tyder på att sjöfararna starkt värderar rekreationsaktiviteter såsom fysisk träning och social interaktion, vilka bidrar till en känsla av normalitet och minskar känslor av isolering. En kritisk faktor är behovet av stark social sammanhållning, främjad av gemensamma aktiviteter, men studien identifierar även utmaningar såsom bristen på djupgående relationer och behovet av att balansera socialt umgänge med individuella behov. Studien understryker vikten av fortsatta undersökningar för att förbättra sjöfararnas arbetsförhållanden och välbefinnande, och erbjuder insikter för strategiutveckling. / This study explores the significance of social networks and recreational activities for the well-being of a group of Scandinavian seafarers, with a particular focus on how these activities impact their psychosocial health aboard ships. The research highlights the relationship between mental health issues and the availability of recreational opportunities and analyzes the effects of internet and social support in managing isolation and stress. Employing a qualitative methodology with semi-structured interviews and using Social Network Theory, the dynamics and interpersonal relationships aboard are analyzed. The results suggest that seafarers highly value recreational activities such as physical exercise and social interaction, which contribute to a sense of normality and reduce feelings of isolation. A critical factor is the need for strong social cohesion, promoted by shared activities, but the study also identifies challenges such as the lack of deep relationships and the need to balance social engagement with individual needs. The study underscores the importance of continued investigations to improve the working conditions and well-being of seafarers and provides insights for developing strategies that support these goals.

Background: Research in heart disease can be aided by modelling myocardial hemodynamics with knowledge of coronary pressure and vascular resistance measured from the geometry and morphometry of coronary vasculature. This study presents methods to automatically reconstruct accurate detailed coronary vascular anatomical models from high-resolution three-dimensional optical fluorescence cryomicrotomography image volumes for simulating blood flow in coronary arterial trees. Methods: Images of fluorescent cast and bead particles perfused into the same heart comprise the vasculature and microsphere datasets, employed in a novel combined approach to measure vasculature and simulate a flow model on the extracted coronary vascular tree for estimating regional myocardial perfusion. The microspheres are used in two capacities - as fiducial biomarker point sources for measuring the image formation in order to accurately measure the vasculature dataset and as flowing particles for measuring regional myocardial perfusion through the reconstructed vasculature. A new model-based template-matching method of vascular radius estimation is proposed that incorporates a model of the optical fluorescent image formation measured from the microspheres and a template of the vessels’ tubular geometry. Results: The new method reduced the error in vessel radius estimation from 42.9% to 0.6% in a 170 micrometer vessel as compared to the Full-Width Half Maximum method. Whole-organ porcine coronary vascular trees, automatically reconstructed with the proposed method, contained on the order of 92,000+ vessel segments in the range 0.03 – 1.9 mm radius. Discrepancy between the microsphere perfusion measurements and regional flow estimated with a 1-D steady state linear static blood flow simulation on the reconstructed vasculature was modelled with daughter-to-parent area ratio and branching angle as the parameters. Correcting the flow simulation by incorporating this model of disproportionate distribution of microspheres reduced the error from 24% to 7.4% in the estimation of fractional microsphere distribution in oblique branches with angles of 100°-120°.

This thesis addresses orchestration of servers amongst multiple co-hosted internet services such as e-Banking, e-Auction and e-Retail in hosting centres. The hosting paradigm entails levying fees for hosting third party internet services on servers at guaranteed levels of service performance. The orchestration of server ensemble in hosting centres is considered in the context of maximising the hosting centre's revenue over a lengthy time horizon. The inspiration for the server orchestration approach proposed in this thesis is drawn from nature and generally classed as swarm intelligence, specifically, sophisticated collective behaviour of social insects borne out of primitive interactions amongst members of the group to solve problems beyond the capability of individual members. Consequently, the approach is self-organising, adaptive and robust. A new scheme for server ensemble orchestration is introduced in this thesis. This scheme exploits the many similarities between server orchestration in an internet hosting centre and forager allocation in a honeybee (Apis mellifera) colony. The scheme mimics the way a honeybee colony distributes foragers amongst flower patches to maximise nectar influx, to orchestrate servers amongst hosted internet services to maximise revenue. The scheme is extended by further exploiting inherent feedback loops within the colony to introduce self-tuning and energy-aware server ensemble orchestration. In order to evaluate the new server ensemble orchestration scheme, a collection of server ensemble orchestration methods is developed, including a classical technique that relies on past history to make time varying orchestration decisions and two theoretical techniques that omnisciently make optimal time varying orchestration decisions or an optimal static orchestration decision based on complete knowledge of the future. The efficacy of the new biomimetic scheme is assessed in terms of adaptiveness and versatility. The performance study uses representative classes of internet traffic stream behaviour, service user's behaviour, demand intensity, multiple services co-hosting as well as differentiated hosting fee schedule. The biomimetic orchestration scheme is compared with the classical and the theoretical optimal orchestration techniques in terms of revenue stream. This study reveals that the new server ensemble orchestration approach is adaptive in a widely varying external internet environments. The study also highlights the versatility of the biomimetic approach over the classical technique. The self-tuning scheme improves on the original performance. The energy-aware scheme is able to conserve significant energy with minimal revenue performance degradation. The simulation results also indicate that the new scheme is competitive or better than classical and static methods.

The self-assembly of structured particles into monodisperse clusters is a challenge on the nano-, micro- and even macro-scale. While biological systems are able to self-assemble with comparative ease, many aspects of this self-assembly are not fully understood. In this thesis, we look at the strategies and rules that can be applied to encourage the formation of monodisperse clusters. Though much of the inspiration is biological in nature, the simulations use a simple minimal patchy particle model and are thus applicable to a wide range of systems. The topics that this thesis addresses include: Encapsulation: We show how clusters can be used to encapsulate objects and demonstrate that such `templates' can be used to control the assembly mechanisms and enhance the formation of more complex objects. Hierarchical self-assembly: We investigate the use of hierarchical mechanisms in enhancing the formation of clusters. We find that, while we are able to extend the ranges where we see successful assembly by using a hierarchical assembly pathway, it does not straightforwardly provide a route to enhance the complexity of structures that can be formed. Pore formation: We use our simple model to investigate a particular biological example, namely the self-assembly and formation of heptameric alpha-haemolysin pores, and show that pore insertion is key to rationalising experimental results on this system. Phase re-entrance: We look at the computation of equilibrium phase diagrams for self-assembling systems, particularly focusing on the possible presence of an unusual liquid-vapour phase re-entrance that has been suggested by dynamical simulations, using a variety of techniques.

During human immunodeficiency virus 1 (HIV-1) infection, the viral population is in constant battle with the host immune system. The cytotoxic T-lymphocyte (CTL) response, a branch of the adaptive immune response, is implicated in viral control and can drive viral evolution in the infected host population. Endogenous viral peptides, or ‘epitopes’, are presented to CTLs by human leukocyte antigen (HLA) class I molecules on the surface of infected cells where they may be identified as non-self. Mutations in or proximal to a viral epitope can result in ‘escape’ from CTLs targeting that epitope. The repertoire of epitopes which may be presented is dependent upon host class I HLA types. As such, reversion may occur after transmission due to changes in viral fitness and selection in the context of a new HLA background. Thus, parameters describing the dynamics of CTL escape and reversion are key to understanding how CTL responses within individuals relate to HIV-1 sequence evolution in the infected host population. Escape and reversion can be studied directly using biological assays and longitudinal viral sequence data, or indirectly by considering viral sequences across multiple hosts. Indirect approaches include tree based methods which detect associations between host HLA and viral sequence but do not estimate rates of escape and reversion, and ordinary differential equation (ODE) models which estimate these rates but do not consider the dependency structure inherent in viral sequence data. We introduce two models which estimate escape and reversion rates whilst accounting for the shared ancestry of viral sequence data. For our first model, we lay out an integrated Bayesian approach which combines genealogical inference and an existing epidemiological model to inform escape and reversion rate estimates. Using this model, we find evidence for correlation between escape rate estimates across widely separated geographical regions. We also observe a non-linear negative correlation between in vitro replicative capacity and escape rate. Both findings suggest that epistasis does not play a strong role in the escape process. Although our first model worked well, it had some key limitations which we address in our second method. Notably, by making a series of approximations, we are able account for recombination and analyse very large datasets which would be computationally infeasible under the first model. We verify our second approach through extensive simulations, and use the method to estimate both drug and HLA associated selection along portions of the HIV-1 genome. We test the results of the model using existing knowledge, and determine a collection of putative selected sites which warrant further investigation. Finally, we find evidence to support the notion that the CTL response played a role in HIV-1 subtype diversification.

Harmonia axyridis is a ladybird native to Asia, but introduced widely as a biocontrol agent. It is invasive and detrimental to native species in North America, which meant its arrival in Britain was met with concern. Establishment was seen as an opportunity to track the spread of an invasive alien species (IAS) whilst also monitoring impacts on native species. The aims of this thesis were to examine the responses of native British ladybirds to the arrival of H. axyridis, to establish the effect of the IAS on native ladybirds when compared to other drivers, and to investigate the possible facilitation of the H. axyridis invasion by natural enemy release. Modelling ladybird distributions with life-history and resource-use traits found that species predatory on a wide range of prey families had larger range sizes than those which ate fewer prey types. This suggests that the wide diet breadth of the IAS is likely to have played a critical role in the species’ rapid spread. Dietary niche overlap between H. axyridis and native ladybirds showed positive correlation with declines of native ladybirds. This indicates that the IAS is playing an important role, but the significance of urbanisation suggests habitat destruction is also significant. Abundance of H. axyridis was influenced by habitat type and aphid abundance, but not by the native ladybird community, suggesting the spread of the IAS will not be slowed by biotic resistance. Harmonia axyridis is attacked by native parasitoids, but at a much lower rate than is the native Coccinella septempunctata, in line with natural-enemy release theory. There was no evidence of attack rate increasing with time since arrival in an area. Overall, H. axyridis is an extremely successful IAS, with detrimental effects on native ladybirds which are likely to continue.

The astonishing progress of molecular biology, engineering and computer science has resulted in mature technologies capable of examining multiple cellular components at a genome-wide scale. Protein-protein interactions are one example of such growing data. These data are often organised as networks with proteins as nodes and interactions as edges. Albeit still incomplete, there is now a substantial amount of data available and there is a need for biologically meaningful methods to analyse and interpret these interactions. In this thesis we focus on how to compare protein interaction networks (PINs) and on the rela- tionship between network architecture and the biological characteristics of proteins. The underlying theme throughout the dissertation is the use of small subgraphs – small interaction patterns between 2-5 proteins. We start by examining two popular scores that are used to compare PINs and network models. When comparing networks of the same model type we find that the typical scores are highly unstable and depend on the number of nodes and edges in the networks. This is unsatisfactory and we propose a method based on non-parametric statistics to make more meaningful comparisons. We also employ principal component analysis to judge model fit according to subgraph counts. From these analyses we show that no current model fits to the PINs; this may well reflect our lack of knowledge on the evolution of protein interactions. Thus, we use explanatory variables such as protein age and protein structural class to find patterns in the interactions and subgraphs we observe. We discover that the yeast PIN is highly heterogeneous and therefore no single model is likely to fit the network. Instead, we focus on ego-networks containing an initial protein plus its interacting partners and their interaction partners. In the final chapter we propose a new, alignment-free method for network comparison based on such ego-networks. The method compares subgraph counts in neighbourhoods within PINs in an averaging, many-to-many fashion. It clusters networks of the same model type and is able to successfully reconstruct species phylogenies solely based on PIN data providing exciting new directions for future research.

Syftet med följande litteraturstudie är att belysa hur elever i förskolan till årskurs sex förhåller sig till hållbar utveckling. Litteraturstudien ger en presentation kring elevers synsätt på de tre dimensionerna inom hållbar utveckling. Härtill framförs det hur begreppet hållbar utveckling har vuxit fram samt en sammanställning av nationella och internationella diskussioner om hur världen kan arbeta mot en hållbar framtid. Vidare presenteras det hur hållbar utveckling framträder i den svenska läroplanen. Det resultat som framkom inkluderar undersökningar från Sverige, Turkiet och USA, där elever under intervju eller med hjälp av illustrationer fick visualisera sin uppfattning på vad som väntar människan och planeten. I undersökningarna indikerade elever en generell oro gällande miljön och framtiden. Majoriteten av eleverna kunde ge uttryck för en koppling mellan de tre dimensionerna av hållbar utveckling. Härtill visade eleverna i en annan studie en generell rädsla för miljöproblem vilket återges som ”ekofobiska” idéer. I litteraturstudien förs slutligen en diskussion om införandet av ett nytt ämne i läroplanen, vikten av ett paradigmskifte samt hur undervisning kring hållbar utveckling kan exemplifieras i klassrummet. / The purpose of this study is to clarify how pupils in pre-school and the grades one to six relate to sustainable development. The literature study presents pupils´ perspectives on the three dimensions in sustainable development. Furthermore, it is presented how the concept sustainable development has expanded. The study also presents a summary of national and international discussions about how the world can work towards a sustainable future. Additionally it is presented how sustainable development stands in the Swedish curriculum. The study includes surveys from Sweden, Turkey and USA, where pupils during interviews or through illustrations visualized their view on what awaits the human kind and the planet. The result indicates a general concern regarding the environment and the future. A majority of the pupils could not refer to a connection between the three dimensions of sustainable development. Pupils indicated an overall anxiety for environmental problems, which can be redirected as “ecophobic” ideas. Finally, there is a discussion about an imposition of Sustainable development as an individual subject in the curriculum, the importance of a paradigm shift and how teaching about sustainable development can be exemplified in the classroom.

Modelling and simulation are essential to modern research in cell biology. This thesis follows a journey starting from the construction of new stochastic methods for discrete biochemical systems to using them to simulate a population of interacting haematopoietic stem cell lineages. The first part of this thesis is on discrete stochastic methods. We develop two new methods, the stochastic extrapolation framework and the Stochastic Bulirsch-Stoer methods. These are based on the Richardson extrapolation technique, which is widely used in ordinary differential equation solvers. We believed that it would also be useful in the stochastic regime, and this turned out to be true. The stochastic extrapolation framework is a scheme that admits any stochastic method with a fixed stepsize and known global error expansion. It can improve the weak order of the moments of these methods by cancelling the leading terms in the global error. Using numerical simulations, we demonstrate that this is the case up to second order, and postulate that this also follows for higher order. Our simulations show that extrapolation can greatly improve the accuracy of a numerical method. The Stochastic Bulirsch-Stoer method is another highly accurate stochastic solver. Furthermore, using numerical simulations we find that it is able to better retain its high accuracy for larger timesteps than competing methods, meaning it remains accurate even when simulation time is speeded up. This is a useful property for simulating the complex systems that researchers are often interested in today. The second part of the thesis is concerned with modelling a haematopoietic stem cell system, which consists of many interacting niche lineages. We use a vectorised tau-leap method to examine the differences between a deterministic and a stochastic model of the system, and investigate how coupling niche lineages affects the dynamics of the system at the homeostatic state as well as after a perturbation. We find that larger coupling allows the system to find the optimal steady state blood cell levels. In addition, when the perturbation is applied randomly to the entire system, larger coupling also results in smaller post-perturbation cell fluctuations compared to non-coupled cells. In brief, this thesis contains four main sets of contributions: two new high-accuracy discrete stochastic methods that have been numerically tested, an improvement that can be used with any leaping method that introduces vectorisation as well as how to use a common stepsize adapting scheme, and an investigation of the effects of coupling lineages in a heterogeneous population of haematopoietic stem cell niche lineages.

We investigate the biological constraints determined by the complex relationships between ecological and immunological processes of host-pathogen interactions, with emphasis on influenza viruses in human, which are responsible for a number of pandemics in the last 150 years. We begin by discussing prolegomenous reviews of historical perspectives on the use of theoretical modelling as a complementary tool in public health and epidemiology, current biological background motivating the objective of the thesis, and derivations of mathematical models of multi-locus-allele systems for infectious diseases with co-circulating serotypes. We provide detailed analysis of the multi-locus-allele model and its age-specific extension. In particular, we establish the necessary conditions for the local asymptotic stability of the steady states and the existence of oscillatory behaviours. For the age-structured model, results on the existence of a mild solution and stability conditions are presented. Numerical studies of various strain spaces show that the dynamic features are preserved. Specifically, we demonstrate that discrete antigenic forms of pathogens can exhibit three distinct dynamic features, where antigenic variants (i) fully self-organize and co-exist with no strain structure (NSS), (ii) sort themselves into discrete strain structure (DSS) with non-overlapping or minimally overlapping clusters under the principle of competitive exclusion, or (iii) exhibit cyclical strain structure (CSS) where dominant antigenic types are cyclically replaced with sharp epidemics dominated by (1) a single strain dominance with irregular emergence and re-emergence of certain pathogenic forms, (2) ordered alternating appearance of a single antigenic type in periodic or quasi-periodic form similar to periodic travelling waves, (3) erratic appearance and disappearance of synchrony between discrete antigenic types, and (4) phase-synchronization with uncorrelated amplitudes. These analyses allow us to gain insight into the age-specific immunological profile in order to untangle the effects of strain structures as captured by the clustering behaviours, and to provide public health implications. The age-structured model can be used to investigate the effect of age-specific targeting for public health purposes.