Les forces de sélection sont un des moteurs de l’évolution de la diversité phénotypique et de la diversité génétique neutre et des zones codantes du génome. Cette sélection peut s’appliquer sur des caractères transmis génétiquement ou culturellement. Le travail effectué s’intéresse à ces deux processus de sélection. Nous avons étudié dans un premier temps les effets de la transmission intergénérationnelle de la fécondité sur la diversité génétique neutre puis dans un deuxième temps l’impact de la sélection sur des phénotypes codés par des réseaux de gènes sur le polymorphisme de ces gènes.La transmission de la fécondité est un phénomène culturel ou génétique qui se caractérise par une corrélation positive entre la taille de fratrie d’un individu et la taille de fratrie de ses enfants. Il a été observé tant dans des populations humaines qu’animales. Nous montrons, par l’outil de la modélisation, que ses effets et la possibilité de le détecter dépendent autant du type de données étudiées (génétiques ou généalogiques), que des différents types de transmission (uniparentale, biparentale). Nous montrons que d’autres phénomènes, tels que l’hétérogénéité du succès reproducteur des individus, peuvent fortement moduler son impact. Nous développons un certain nombre d’outils permettant de détecter ce phénomène de transmission de la fécondité tant sur des données généalogiques que sur des données génétiques relevant de différents modèles mutationnels (microsatellite, séquences, SNPs) et de différents types de transmission (haploïde ou diploïde, lié au sexe ou non). Nous avons appliqué ces outils notamment à trois populations humaines du Cilento en Italie (généalogies et ADN mitochondrial), des données d’Asie Centrale (chromosome Y) et des données HapMap (autosomes).La seconde partie de la thèse porte sur la modélisation de l’action de la sélection naturelle sur des caractères codés par des réseaux de régulation et décrit l’impact de ce type de sélection sur l’évolution du phénotype et sur la diversité des gènes sous-jacents. Un phénotype est le résultat des interactions entre différents gènes et leurs produits. Nous montrons que la sélection sur ce phénotype va modifier l’organisation du réseau de gènes ainsi que le niveau de polymorphisme des gènes du réseau. Par exemple, lorsque le phénotype optimal correspond à une expression médiane des gènes, les gènes les plus régulateurs vont être soumis à une plus forte perte de diversité. En revanche, si le phénotype optimal correspond à une expression très forte, ce sont les gènes les plus régulés qui vont être les plus contraints. Cette analyse a permis de montrer la complexité des relations entre sélection, réseaux de régulation, phénotypes et environnement. / Selective forces are one of the major determinants of the evolution of phenotypic diversity and genetic diversity, in neutral and coding zones of the genome. Selection can occur on genetically - or culturally - transmitted traits. This thesis considers these two selective processes. First, we studied the effects of intergenerational fertility transmission on neutral genetic diversity. Second, we considered the impact of selection on phenotypes coded by a gene network and on the polymorphism of genes within the network.Fertility transmission is a cultural or genetic phenomenon, which is characterised by a positive correlation between the sibship size of an individual and that of its children. It was observed both in human and animal populations. Using a modelling approach, we show that its effects and the possibility to detect it depend both on the kind of studied data (genetic or genealogical data) and on the different kind of transmission (uniparental, biparental). We show that other phenomena, such as the heterogeneity of reproductive success between individuals, can affect its effects. We develop several tools allowing to infer this phenomenon of fertility transmission on genealogical data, as well as on genetic polymorphism data that follows different mutational models (microsatellites, sequences, SNPs) and different transmission modes (haploid or diploid, sex-linked or not). We applied in particular these tools to three human populations of the Cilento area in Italy (genealogical and mitochondrial DNA data), to Central Asian data (Y chromosome) and to HapMap data (autosomes).The second part of this thesis deals with the modelling of the action of natural selection on traits coded by regulation networks and describes the impact of such selection on the evolution of the phenotype and of the underlying genes. A given phenotype is the result of the interaction between different genes and their products. We show that phenotypic selection will modify the gene network organisation, as well as the level of polymorphism of the genes involved in the network. For example, when the optimal phenotype corresponds to an intermediate level of gene expression, the most regulatory genes will lose much of their diversity. Conversely, if the optimal phenotype corresponds to a very strong expression of the genes, it will be the most regulated genes that will be the most constrained. This analysis allowed us to show the complexity of the relations between selection, regulation networks, phenotypes and the environment.

Sexually transmitted diseases affect millions of lives every year. In order to most effectively use prevention resources epidemiologists deploy models to understand how the disease spreads through the population and which intervention methods will be most effective at reducing disease perpetuation. Increasingly agent-based models are being used to simulate population heterogeneity and fine-grain sociological effects that are difficult to capture with traditional compartmental and statistical models. A key challenge is using a sufficiently large number of agents to produce robust and reliable results while also running in a reasonable amount of time. In this thesis we show the effectiveness of agent-based modeling in planning coordinated responses to a sexually transmitted disease epidemic and present efficient algorithms for running these models in parallel and in a distributed setting. The model is able to account for population heterogeneity like age preference, concurrent partnership, and coital dilution, and the implementation scales well to large population sizes to produce robust results in a reasonable amount of time. The work helps epidemiologists and public health officials plan a targeted and well-informed response to a variety of epidemic scenarios.

Movement patterns and space use by mature fishes are critical in determining the effectiveness of marine reserves in conserving spawning stock biomass and/or providing biomass to adjacent fisheries through 'spillover'. Home range sizes, activity patterns, site fidelity and habitat preferences were determined for acoustically-tagged snappers and groupers using a rigorously-calibrated array of omnidirectional hydroacoustic receivers deployed in the diverse coral reef environments of a no-take marine reserve (NTMR) network in the Dry Tortugas, Florida. An individual-based localizing tendency model of reef fish movement was parameterized from fine-scale acoustic telemetry data and integrated into a Spatial Management Performance Assessment (SMPA) simulation model for reef fish populations developed to quantitatively evaluate performance of no-take marine reserves in the Dry Tortugas, Florida. Spatially-explicit SMPA models were parameterized for three overfished stocks in the lucrative snapper-grouper fishery: red grouper (Epinephelus morio), black grouper (Mycteroperca bonaci), and mutton snapper (Lutjanus analis). SMPA models were used to evaluate the impacts of a variety of life histories, movement strategies and speeds, and management regulations upon long-term stock sustainability, as measured by annual changes in spawning potential ratio (SPR), and long-term stock productivity, as measured by annual changes in fisheries yield-in-weight per recruit (Yw/R). Under assumptions of constant regional fishing pressure, constant recruitment, and 'realistic' fish movement, SMPA simulation runs from initial conditions in 2000 suggested that by 2014, the Tortugas NTMR network should function to restore red grouper populations to 30% SPR, a Federal management benchmark for sustainability. Mutton snapper were the most mobile of the species investigated; if mutton snapper movements are ignored, their population is predicted to attain 30% SPR by 2014, but given 'realistic' mobility, they may not attain this target by 2021 without additional protections. Black grouper are currently fished at over 9 times sustainable levels. SMPA simulations suggest coupling an increase in minimum size at capture of 20 - 25 cm with NTMR implementation would result in substantial short term losses in yield, but would restore both black grouper and mutton snapper populations to 30% SPR by 2021 and lead to increased long-term yields. Although marine reserve sites are often chosen opportunistically, these findings strongly suggest that reserve designs (e.g. proper sizes and configurations) must take into account the scales and patterns of movement exhibited by the exploited stocks they are intended to protect. These modeling efforts also suggested reserves are not a panacea; in order to promote sustainability for severely depleted stocks, they must be accompanied by an overall reduction in fishing capacity. Although important questions remain concerning the movements of reef fish in response to habitat and density dependent processes, our analyses of realistic reef fish behaviors suggest that the NTMRs of the Dry Tortugas promote substantial gains in SPR, promoting long-term stock sustainability and enhanced egg production. Increased rates of movement diminish these benefits, but may also mitigate short-term losses in yield associated with NTMR establishment.

Der Rückgang des Steinkauzes (Athene noctua) hat in Thüringen und Sachsen seit den 60er Jahren dramatische Ausmaße angenommen. In den 50er Jahren noch flächendeckend beobachtet, wurden für das Jahr 2000 nur noch 18 Individuen durch Bestandserfassungen registriert. Die vielfach diskutierten Rückgangsursachen beziehen sich vor Allem auf die großflächige Änderung der Landschaftsstrukturen, die zum Verlust der Lebensgrundlagen des Steinkauzes führten. So haben u.a. der Verlust an Brut- und Vorratshöhlen und an ganzjährig kurzgehaltenen Grünlandflächen, sowie der zunehmende Einfluss von Prädatoren erheblich zum Rückgang beigetragen. Eingeleitete Schutzmaßnahmen, ehrenamtlich oder auf dem allgemeinen Naturschutzprogramm des Freistaates Thüringen beruhend, wie das Anbringen von Nisthilfen mit Marderschutz oder Pflegeverträge für Streuobstwiesen, zeigen bisher keine sichtbare Wirkung. Als weitergehende Maßnahmen stehen die Reduzierung von Füchsen (Vulpes vulpes) und Steinmardern (Martes foina), Ausbreitungskorridore für Steinkäuze und ein Auswilderungsprogramm zur Diskussion. Angesichts des Populationsrückgangs des Steinkauz war es Aufgabe dieser Arbeit durch ein Simulationsmodell Untersuchungen zum Überleben einer Steinkauzpopulation (Athene noctua) in Thüringen durchzuführen. Die zusammengetragenen Bestandszahlen ergaben geringe Individuenzahlen in den thüringischen Landkreisen Altenburger Land, Greiz und der Stadt Gera sowie in den sächsischen Landkreisen Chemnitzer Land und Mittweida. Die Bestandszahlen der Jahre 1989-2001, sowie weitere der Literatur entnommene Daten zum populationsökologischen Hintergrund, wie auch Analysen des Gebietes in Thüringen und Sachsen und dessen besetzter Reviere der Jahre 1989- 2001, wurden in ein stochastisches, räumlich-explizites, auf Individuen basierendes Simulationsmodell eingebracht. Es wurde eine Sensitivitätsanalyse durchgeführt, die beruhend auf den erfassten Populationsentwicklungen in Thüringen und Sachsen und auf Literaturangaben, ausgewählte Parameterkonstellationen für die Untersuchungenergab. Die Untersuchungen zum Überleben vor dem Hintergrund möglicher Gefährdungsfaktoren und zur Ermittelung des Nutzens von Managementoptionen, wurden mit Schwerpunkten auf „Prädation“, „Habitatverbesserung“ und „Auswilderung“ durchgeführt. Als Ergebnis der Simulationen kam heraus, dass die Prädation keinen großen Einfluss auf das Überleben der Population hat, und Schutzmaßnahmen die Chancen für das Überleben der Population nicht erhöhen würden. Habitatverbesserungen, die die Juvenilen animieren sich im Umkreis von bis zu 5 km vom elterlichen Revier anzusiedeln, würden aber deutlich zum Überleben der Population, auch in längerfristiger Perspektive, beitragen. Habitatverbesserungen, die zu weiter entfernteren Ansiedlungen animieren, könnten sich dagegen ungünstig auf das Überleben der Population auswirken. Für eine mögliche Auswilderung als Schutzmaßnahme ergab sich im Modell, dass eine Auswilderung von 5 Individuen pro Jahr über einen Zeitraum von 5 Jahren, die Überlebenswahrscheinlichkeit kurzfristig deutlich verbessern würde. Es ergab sich allerdings kein Unterschied, ob 5, 10 oder 15 Individuen ausgewildert werden. Eine länger durchgeführte Auswilderung würde vermutlich die Überlebenswahrscheinlichkeit entsprechend langfristiger verbessern.

Fire prone Mediterranean-type vegetation systems like those in the Mediterranean Basin and South-Western Australia are global hot spots for plant species diversity. To ensure management programs act to maintain these highly diverse plant communities, it is necessary to get a profound understanding of the crucial mechanisms of coexistence. In the current literature several mechanisms are discussed. The objective of my thesis is to systematically explore the importance of potential mechanisms for maintaining multi-species, fire prone vegetation by modelling. The model I developed is spatially-explicit, stochastic, rule- and individual-based. It is parameterised on data of population dynamics collected over 18 years in the Mediterranean-type shrublands of Eneabba, Western Australia. From 156 woody species of the area seven plant traits have been identified to be relevant for this study: regeneration mode, annual maximum seed production, seed size, maximum crown diameter, drought tolerance, dispersal mode and seed bank type. Trait sets are used for the definition of plant functional types (PFTs). The PFT dynamics are simulated annual by iterating life history processes. In the first part of my thesis I investigate the importance of trade-offs for the maintenance of high diversity in multi-species systems with 288 virtual PFTs. Simulation results show that the trade-off concept can be helpful to identify non-viable combinations of plant traits. However, the Shannon Diversity Index of modelled communities can be high despite of the presence of ‘supertypes’. I conclude, that trade-offs between two traits are less important to explain multi-species coexistence and high diversity than it is predicted by more conceptual models. Several studies show, that seed immigration from the regional seed pool is essential for maintaining local species diversity. However, systematical studies on the seed rain composition to multi-species communities are missing. The results of the simulation experiments, as presented in part two of this thesis, show clearly, that without seed immigration the local species community found in Eneabba drifts towards a state with few coexisting PFTs. With increasing immigration rates the number of simulated coexisting PFTs and Shannon diversity quickly approaches values as also observed in the field. Including the regional seed input in the model is suited to explain more aggregated measures of the local plant community structure such as species richness and diversity. Hence, the seed rain composition should be implemented in future studies. In the third part of my thesis I test the sensitivity of Eneabba PFTs to four different climate change scenarios, considering their impact on both local and regional processes. The results show that climate change clearly has the potential to alter the number of dispersed seeds for most of the Eneabba PFTs and therefore the source of the ‘immigrants’ at the community level. A classification tree analysis shows that, in general, the response to climate change was PFT-specific. In the Eneabba sand plains sensitivity of a PFT to climate change depends on its specific trait combination and on the scenario of environmental change i.e. development of the amount of rainfall and the fire frequency. This result emphasizes that PFT-specific responses and regional process seed immigration should not be ignored in studies dealing with the impact of climate change on future species distribution. The results of the three chapters are finally analysed in a general discussion. The model is discussed and improvements and suggestions are made for future research. My work leads to the following conclusions: i) It is necessary to support modelling with empirical work to explain coexistence in species-rich plant communities. ii) The chosen modelling approach allows considering the complexity of coexistence and improves the understanding of coexistence mechanisms. iii) Field research based assumptions in terms of environmental conditions and plant life histories can relativise the importance of more hypothetic coexistence theories in species-rich systems. In consequence, trade-offs can play a lower role than predicted by conceptual models. iv) Seed immigration is a key process for local coexistence. Its alteration because of climate change should be considered for prognosis of coexistence. Field studies should be carried out to get data on seed rain composition. / Feuer geprägte, mediterrane Vegetationstypen, wie sie im Mittelmeerraum und Süd-West Australien zu finden sind, gelten als globale „hotspots“ für Pflanzendiversität. Um sicher zu stellen, dass Managementprogramme zum Erhalt dieser hoch diversen Pflanzengesellschaften zielgerichtet beitragen, ist ein profundes Verständnis der wesentlichen Koexistenzmechanismen notwendig. In der aktuellen Literatur werden verschiedene Mechanismen diskutiert. Das Ziel meiner Doktorarbeit ist es, die Bedeutung der Mechanismen für den Erhalt der artenreichen, feuergeprägten Vegetation anhand eines Modells systematisch zu untersuchen. Das von mir dafür entwickelte Modell ist räumlich-explizit, stochastisch und regel- und individuenbasiert. Es ist unter Zuhilfenahme von Daten zu Populationsdynamiken parametrisiert, die über 18 Jahre im Mediterranen Buschland von Eneabba Westaustraliens gesammelt wurden. Anhand von 156 Arten sind sieben für meine Studie relevante Pflanzeneigenschaften identifiziert wurden: Regenerationsart, jährlich maximale Samenproduktion, Samengröße, maximaler Durchmesser, Trockentoleranz, Ausbreitungsart und Samenbanktyp. Kombinationen der Eigenschaften bilden funktionelle Pflanzentypen (PFTs), deren jährliche Dynamik über Lebenszyklusprozesse im Modell simuliert wird. Der erste Teil meiner Arbeit präsentiert die Studie zur Bedeutung von „trade-offs“ für den Erhalt der hohen Diversität in artenreichen Systemen. Die Simulationsergebnisse mit 288 virtuellen PFTs zeigen, dass das „trade-offs“-Konzept für die Identifizierung nicht-lebensfähiger Kombinationen von Pflanzeneigenschaften hilfreich sein kann. Allerdings kann der Shannon-Diversitäts-Index der modellierten Pflanzengesellschaft trotz der Anwesenheit von „Supertypen“ hoch sein. Ich schlussfolgere, dass „trade-off“ zwischen zwei Eigenschaften weniger wichtig für die Erklärung der Koexistenz von vielen Arten und hoher Diversität sind, als es durch konzeptionelle Modelle vorhergesagt wird. Viele Studien zeigen, dass Sameneintrag aus dem regionalen Samenpool essenziell für den Erhalt lokaler Artendiversität ist. Es gibt allerdings noch keine systematischen Studien zur Zusammensetzung des Samenregens artenreichen Systemen. Die Ergebnisse der Simulationsexperimente im zweiten Teil meiner Arbeit machen deutlich, dass ohne Sameneintrag die lokale Pflanzengesellschaft Eneabbas sich in eine Richtung entwickelt, in der nur wenige PFTs koexistieren. Mit steigender Samenimmigrationsrate erreicht die Anzahl an koexistierenden PFTs und die Shannon-Diversität schnell die Werte, die auch im Feld gefunden werden. Der regionale Sameneintrag kann also als Erklärung zur Struktur lokaler Pflanzengesellschaften dienen. Seine Zusammensetzung sollte jedoch in zukünftigen Studien berücksichtigt werden. Im dritten Teil meiner Doktorarbeit präsentiere ich Analysen zur Sensibilität der PFTs von Eneabba vorhergesagte Klimaszenarien und der Auswirkungen auf die Samenimmigration. Die Ergebnisse zeigen deutlich, dass Klimaänderungen das Potential haben, die Anzahl an ausgebreiteten Samen der meisten Eneabba PFTs zu verändern. Die Entscheidungsbaum-Analyse veranschaulicht, dass die Reaktion auf Klimaänderung PFT-spezifisch ist. In den Eneabba hängt die Sensitivität der PFTs gegenüber klimatischen Veränderungen von den PFT-spezifischen Eigenschaftskombinationen und vom Klimaszenarium ab, d.h. von der Entwicklung der Regenfallmenge und der Feuerfrequenz. Dieses Ergebnis betont, dass PFT-spezifische Reaktionen und die klimabedingten Änderungen in der Samenimmigration in Studien zum Einfluss von Klimaänderungen auf die zukünftige Artenverteilung berücksichtigt werden sollten. Die Ergebnisse aus den drei Kapiteln werden in der allgemeinen Diskussion zusammengeführt und analysiert. Das Modell wird diskutiert und Verbesserungen und Vorschläge für weitere Forschung aufgezeigt. Meine Arbeit führt zu folgenden Schlussfolgerungen: i) Es ist notwendig, empirische Arbeit und Modellierung zu kombinieren, um Koexistenz in artenreichen Systemen zu erklären. ii) Durch den gewählten Modellansatz kann die Komplexität von Koexistenz erfasst und das Verständnis vertieft werden. iii) Auf Felddaten basierende Annahmen bezüglich Umweltbedingungen und Lebenzyklus können zur Relativierung der Bedeutsamkeit von Mechanismen führen. So können Trade-offs eine geringere Rolle spielen, als konzeptionelle Modelle nahe legen. iv) Samenimmigration ist ein Schlüsselprozess für lokale Koexistenz. Deren Änderung aufgrund von Klimawandel sollte für Prognosen zu Artenvorkommen berücksichtigt werden. Feldstudien sollten durchgeführt werden, um die Datenlücken zur Samenregenzusammensetzung zu füllen.

This thesis aims at a better mechanistic understanding of animal communities. Therefore, an allometry- and individual-based model has been developed which was used to simulate mammal and bird communities in heterogeneous landscapes, and to to better understand their response to landscape changes (habitat loss and fragmentation). / Diese Doktorarbeit strebt ein besseres mechanistisches Verständnis von Tiergemeinschaften an. Dafür wurde ein allometrie- und individuen-basiertes Modell entwickelt und dazu benutzt, Säugetier- und Vogelgemeinschaften in heterogenen Landschaften zu simulieren, und ihre Reaktion auf Landschaftsveränderungen (Habitatverlust und -fragmentierung) besser zu verstehen.

The paper presents a simulation and parameter-estimation approach for evaluating stochastic patterns of population growth and spread of an annual forest herb, Melampyrum pratense (Orobanchaceae). The survival of a species during large-scale changes in land use and climate will depend, to a considerable extent, on its dispersal and colonisation abilities. Predictions on species migration need a combination of field studies and modelling efforts. Our study on the ability of M. pratense to disperse into so far unoccupied areas was based on experiments in secondary woodland in NE Germany. Experiments started in 1997 at three sites where the species was not yet present, with 300 seeds sown within one square meter. Population development was then recorded until 2001 by mapping of individuals with a resolution of 5 cm. Additional observations considered density dependence of seed production. We designed a spatially explicit individual-based computer simulation model to explain the spatial patterns of population development and to predict future population spread. Besides primary drop of seeds (barochory) it assumed secondary seed transport by ants (myrmecochory) with an exponentially decreasing dispersal tail. An important feature of populationpattern explanation was the simultaneous estimation of both population-growth and dispersal parameters from consistent spatio-temporal data sets. As the simulation model produced stochastic time series and random spatially discrete distributions of individuals we estimated parameters by minimising the expectation of weighted sums of squares. These sums-ofsquares criteria considered population sizes, radial population distributions around the area of origin and distributions of individuals within squares of 25*25 cm, the range of density action. Optimal parameter values, together with the precision of the estimates, were obtained from calculating sums of squares in regular grids of parameter values. Our modelling results showed that transport of fractions of seeds by ants over distances of 1…2 m was indispensable for explaining the observed population spread that led to distances of at most 8 m from population origin within 3 years. Projections of population development over 4 additional years gave a diffusion-like increase of population area without any “outposts”. This prediction generated by the simulation model gave a hypothesis which should be revised by additional field observations. Some structural deviations between observations and model output already indicated that for full understanding of population spread the set of dispersal mechanisms assumed in the model may have to be extended by additional features of plant-animal mutualism.

Biofilms are communities of sessile microorganisms attached to a surface and imbeddedin a matrix of extracellular polysaccharide substances. These communities can be foundin diverse aquatic environments, such as in industrial pipes and in humans. By formingmicrocolony structures, which are highly resistant to adverse physical conditions as wellas antimicrobial agents, biofilms are very problematic when associated with e.g.persistent infections. In order to find new ways of controlling biofilm growth, theprocesses involved in biofilm development must be investigated further. The maininterest of this study is the occurrence of void formation inside biofilms. Thisphenomenon has been observed in several studies and has been correlated to cell deathinside the microcolonies. The occurrence of cell death has recently been associated withthe presence of nitric oxide in the biofilm. In this study, the implications of nitric oxideaccumulation on biofilm development were investigated using an individual-basedmodel. Specifically, the role of nitric oxide in void formation was considered. A largenumber of simulations were run using different parameter settings in order to determine ifnitric oxide could account for the occurrence of void formation observed experimentally.The general predictions made by the model system showed agreement to someexperimental data, but not to others. Sloughing, the detachment of chunks of cells fromthe biofilm, was observed in the majority of simulations. In some cases, the model alsopredicted the presence of live cells inside the voids, which has been observedexperimentally.

I dagens skola är individen och dennes behov i fokus. Detta uttrycks i skolans läroplan, Lpo 94. Läroplanens intention är att undervisningen skall individanpassas utifrån varje elevs behov och förutsättningar. Syftet med studien är att undersöka hur pedagoger individanpassar undervisningen. Vidare är studiens syfte att belysa pedagogers syn på individanpassad undervisning och vad det är som styr deras utformning av den. Antalet respondenter i studien har varit fyra pedagoger, som alla är verksamma i skolår 3. Studien utgörs av en fallstudie med observationer och intervjuer, vilka har analyserats och tolkats. Resultatet visar att pedagoger använder sig av ett varierande arbetssätt för att möta varje enskild elev. De använder planeringsbok, arbetsschema eller beting i arbetet med att individanpassa undervisningen, vilket innebär att eleverna arbetar självständigt och att uppgifterna ofta är självinstruerande. Pedagogerna anser det enklare att individanpassa i matematik och svenska än i idrott, engelska och de natur- och samhällsorienterande ämnena. Studiens resultat visar att en av fördelarna med individanpassad undervisning är att den utgår just från den enskilde eleven. När undervisningen anpassas efter elevens förmåga och behov, leder det till att eleven känner glädje och en känsla av att den kan. Pedagogerna synliggör i detta sammanhang också möjligheten som ges att kunna utmana de duktiga eleverna. Studiens resultat visar att pedagoger vill arbeta mer individanpassat än vad de gör idag, men ser de yttre faktorerna som hinder för detta. / In the school of today, the individual's needs are the focus. This is expressed in Lpo 94. The intention of the curriculum (Lpo 94) is that education should be adjusted to the needs and conditions of every pupil. The purpose of the study is to examine how pedagogues adjust education to the individual. Furthermore, the purpose is to illustrate pedagogues' view on individually based education, and what dictates how it is carried out. Four pedagogues, all working in school year 3, responded to the study. This case study used observations and interviews, which have been analysed. The result shows that pedagogues use a variety of ways to meet the needs of every single pupil. They use planning books, working schedules and/or assignments as learning tools. This implies that the pupils work independently, and that work is often self-instructive. The pedagogues state that it is easier to adjust to the individual's needs in mathematics and Swedish than in physical education, foreign languages, social studies and science. All pedagogues see from a pupil's perspective when talking about the advantages with individually based teaching. They emphasize that the advantage is the possibility to adjust to the abilities and needs of each individual pupil, which leads to a more positive pupil and sense of accomplishment. Individually based teaching also gives the pedagogues the possibility to challenge high achieving pupils. All pedagogues want to work more individually based, but see external factors as impediments.

La microbiologia predictiva és una de les parts més importants de la microbiologia dels aliments. En el creixement d'un cultiu bacterià es poden observar quatre fases: latència, exponencial, estacionària i mort. La fase de latència té un interès específic en microbiologia predictiva; al llarg de dècades ha estat abordada des de dues perspectives diferents: a nivell cel·lular i intracel·lular (escala microscòpica), i a nivell de població (escala macroscòpica). La primera estudia els processos que tenen lloc a l'interior dels bacteris durant la seva adaptació a les noves condicions del medi, com els canvis en l'expressió gènica i en el metabolisme. La segona descriu l'evolució de la població bacteriana per mitjà de models matemàtics continus i d'experiments que avaluen variables relacionades amb la densitat cel·lular. L'objectiu d'aquest treball és millorar la comprensió de la fase de latència dels cultius bacterians i dels fenòmens intrínsecs a la mateixa. Aquest objectiu s'ha abordat amb la metodologia Individual-based Modelling (IbM) amb el simulador INDISIM (INDividual DIScrete SIMulation), que ha calgut optimitzar. La IbM introdueix una perspectiva mecanicista a través de la modelització de les cèl·lules com a unitats bàsiques. Les simulacions IbM permeten estudiar el creixement d'entre 1 i 106 bacteris, així com els fenòmens que emergeixen de la interacció entre ells. Aquests fenòmens pertanyen al que anomenem escala mesoscòpica. Aquesta perspectiva és imprescindible per entendre l'efecte en la població dels processos d'adaptació individuals. Per tant, la metodologia IbM és un pont entre els individus i la població o, el que és el mateix, entre els models a escala microscòpica i a escala macroscòpica.En primer lloc hem estudiat dos dels diversos mecanismes que poden causar la fase de latència: inòculs amb massa mitjana petita, i canvis de medi.S'ha verificat també la relació de la durada de la latència amb variables com la temperatura o la grandària de l'inòcul. En aquest treball s'ha identificat la distribució de biomassa del cultiu com una variable cabdal per analitzar l'evolució del cultiu durant el cicle de creixement. S'han definit les funcions matemàtiques que anomenem distàncies per avaluar quantitativament l'evolució d'aquesta distribució.Hem abordat, també, la fase de latència des d'un punt de vista teòric. L'evolució de la velocitat de creixement al llarg del cicle ha permès distingir dues etapes en la fase de latència que anomenem inicial i de transició. L'etapa de transició s'ha descrit per mitjà d'un model matemàtic continu validat amb simulacions INDISIM. S'ha constatat que la fase de latència ha de ser vista com un procés dinàmic, i no com un simple període de temps descrit per un paràmetre. Les funcions distància també s'han utilitzat per avaluar les propietats del creixement balancejat.Alguns dels resultats de les simulacions amb INDISIM s'han corroborat experimentalment per mitjà de citometria de flux. S'ha comprovat, al llarg de les diverses fases del creixement, el comportament de la distribució de biomassa previst per simulació, així com l'evolució de les funcions distància. La coincidència entre els resultats experimentals i els de simulació no és trivial, ja que el sistema estudiat és molt complex. Per tant, aquests resultats permeten comprovar la bondat de la metodologia INDISIM.Finalment, hem avançat en l'optimització d'eines per parametritzar IbMs, un pas essencial per poder utilitzar les simulacions INDISIM de manera quantitativa. S'han adaptat i assajat els mètodes grid search, NMTA i NEWUOA. Aquest darrer mètode ha donat els millors resultats en termes de temps, mantenint una bona precisió en els valors òptims dels paràmetres. Per concloure, podem afirmar que INDISIM ha estat validat com una bona eina per abordar l'estudi dels estats transitoris com la fase de latència. / Predictive food microbiology has become an important specific field in microbiology. Bacterial growth of a batch culture may show up to four phases: lag, exponential, stationary and death. The bacterial lag phase, which is of specific interest in the framework of predictive food microbiology, has generally been tackled with two generic approaches: at a cellular and intracellular level, which we call the microscopic scale, and at a population level, which we call the macroscopic scale. Studies at the microscopic level tackle the processes that take place inside the bacterium during its adaptation to the new conditions such as the changes in genetic expression and in metabolism. Studies at the macroscopic scale deal with the description of a population growth cycle by means of mathematical continuous modelling and experimental measurements of the variables related to cell density evolution.In this work we aimed to improve the understanding of the lag phase in bacterial cultures and the intrinsic phenomena behind it. This has been carried out from the perspective of Individual-based Modelling (IbM) with the simulator INDISIM (INDividual DIScrete SIMulation), which has been specifically improved for this purpose. IbM introduces a mechanistic approach by modelling the cell as an individual unit. IbM simulations deal with 1 to 106 cells, and allow specific study of the phenomena that emerge from the interaction among cells. These phenomena belong to the mesoscopic level.Mesoscopic approaches are essential if we are to understand the effects of cellular adaptations at an individual level in the evolution of a population.Thus, they are a bridge between individuals and population, or, to put it another way, between models at a microscopic scale and models at a macroscopic scale.First, we studied separately two of the several mechanisms that may cause a lag phase: the lag caused by the initial low mean mass of the inoculum, and the lag caused by a change in the nutrient source. The relationship among lag duration and several variables such as temperature and inoculum size were also checked. This analysis allowed identification of the biomass distribution as a very important variable to follow the evolution of the culture during the growth cycle. A mathematical tool was defined in order to assess its evolution during the different phases of growth: the distance functions.A theoretical approach to the culture lag phase through the dynamics of the growth rate allowed us to split this phase into two stages: initial and transition. A continuous mathematical model was built in order to shape the transition stage, and it was checked with INDISIM simulations. It was seen that the lag phase must be defined as a dynamic process rather than as a simple period of time. The distance functions were also used to discuss the balanced growth conditions.Some of the reported INDISIM simulation results were subjected to experimental corroboration by means of flow cytometry, which allow the assessment of size distributions of a culture through time. The dynamics of biomass distribution given by INDISIM simulations were checked, as well as the distance function evolution during the different phases of growth. The coincidence between simulations and experiments is not trivial: the system under study is complex; therefore, the coincidence in the dynamics of the different modelled parameters is a validation of both the model and the simulation methodology.Finally, we have made progress in IbM parameter estimation methods, which is essential to improve quantitative processing of INDISIM simulations.Classic grid search, NMTA and NEWUOA methods were adapted and tested, the latter providing better results with regard to time spent, which maintains satisfactory precision in the parameter estimation results.Above all, the validity of INDISIM as a useful tool to tackle transient processes such as the bacterial lag phase has been amply demonstrated.