About 70% of the plant species in the temperate zone are characterised by clonal growth, clonal species are also in majority in the Arctic and Subarctic where they affect the structure and composition of the vegetation. It is therefore of great importance to increase our knowledge about clonal plants and their growth and life histories. I have investigated how ramets of the stoloniferous plant Linnaea borealis are affected by the naturally occurring variation in environmental factors, such as: light, nutrient and water availability. Moreover, I examined the seed set and how supplemental hand pollination affects seed set in L. borealis, and also investigated the significance of the apical meristem for shoot population fitness. All studies were performed under field conditions in northern Sweden in a Subarctic environment and most are experimental. The results show that nutrient resorption from senescing leaves is not significantly affecting the growth and nutrient pools of the ramet. This implies that the growth of L. borealis ramets is not governed by micro-site resource availability. However, removal of light competition resulted in increased branching and number of lateral meristems produced, reduced growth, and decreased root:shoot ratio on a per ramet basis. Thus, ramets of L. borealis can efficiently exploit favourable light patches through plastic growth. Apical dominance exerts a significant effect on shoot population fitness and can be lost through rodent grazing. However, loss of apical dominance is dependent on the timing of grazing, if the apical meristem is removed early in the autumn the ramet can repair the loss until the next summer. If grazing occur during spring the dry weight and leaf area production is affected negatively. Seed production in L. borealis in the Abisko area varies between years and sites, and was unaffected by supplemental hand pollination treatment, implying that there is no lack of pollinator activity.

Dagens svenska arbetsmarknad är i förändringsfasen där tillsvidareanställningen inte är lika dominerande. Istället eftersträvar alltfler en mer flexibel arbetssituation vilket kan liknas vid att frilansa. Det har myntat begreppet gig-ekonomi som innebär att individer hyr ut sig själva på projektbasis. Trots att det finns en strävan efter en mer flexibel arbetsmarknad är det fortfarande många som söker en tillsvidareanställning men har fastnat i en tidsbegränsad anställning. De olika anställningsformerna har skapat debatt i Sverige och fokuserar främst på konsekvenserna för arbetstagaren. Syftet med vår studie är att bidra med kunskap om vilka konsekvenser tidsbegränsade anställningar har för organisationen. För att besvara vår frågeställning har vi valt en kvalitativ metod och genomfört en fallstudie. Vårt empiriska material består främst av intervjuer och observationer på en skola. För att analysera vårt material används teorier som beskriver organisationens uppbyggnad samt behandlar individen, gruppen, mellanchefen och den strategiska ledningen. Vår övergripande slutsats är att tidsbegränsade anställningar har en påverkan på samtliga nivåer i organisationen. Den tidsbegränsade anställningen skapar osäkerhet för både individen och gruppen vilket kan hämma organisationens effektivitet. / The current Swedish labor market is changing. Permanent positions are no longer as dominant and instead, many people are looking for a more flexible working situation, much like freelancing. This has led to the newly coined term “gig-economy”, which practically means that organizations contract with independent workers for short- term engagements. However, there are still many who seek a permanent position, but might be stuck in a temporary position. The use of temporary positions has become more common in several sectors which has created a debate in Sweden. The debate focuses mainly on the consequences for the individual worker. The purpose of our study is to contribute with knowledge on what consequences temporary employment has for the organization. To fulfill our purpose, we’ve chosen to use a qualitative method to conduct a case study. Our empirical material consists mainly of interviews and observations at an elementary school. In order to analyze our material, we’ve used theories which describe the organizational structure and which addresses the individual, the group as well as the middle- and strategic management. Our general conclusion is that temporary employment has an impact on all levels of the organization. The temporary positions create insecurity for both the individual and the group and it can hamper the organizations efficiency.

Mounting evidence suggests that large carnivores regulate the abundance and diversity of species at multiple trophic levels through cascading top-down effects. The fear large carnivores inspire in their prey may be a critical component of these top-down effects, buffering lower trophic levels from overconsumption by suppressing large herbivore and mesopredator foraging. However, the evidence that the fear of large carnivores cascades through food webs has been repeatedly challenged because it remains experimentally untested. My collaborators and I exploited a natural experiment – the presence or absence of mesopredator raccoons (Procyon lotor) on islands in the Gulf Islands of British Columbia, Canada – to examine the breadth of mesopredator impacts in a system from which all native large carnivores have been extirpated. By comparing prey abundance on islands with and without raccoons, we found significant negative effects of raccoon presence on terrestrial (songbirds and corvids), intertidal (crabs and fish) and shallow subtidal (red rock crabs Cancer productus) prey, demonstrating that, in the absence of native large carnivores, mesopredator impacts on islands can extend across ecosystem boundaries to affect both terrestrial and marine communities. To test whether fear of large carnivores can mitigate these community-level impacts of mesopredators, we experimentally manipulated fear in free-living raccoon populations using month-long playbacks of large carnivore vocalizations and monitored the effects on raccoon behaviour and the intertidal community. Fear of large carnivores reduced raccoon foraging to the benefit of the raccoon’s prey, which in turn affected a competitor and prey of the raccoon’s prey. By experimentally restoring the fear of large carnivores in our study system, we succeeded in reversing the impacts of raccoons, reinforcing the need to protect large carnivores given the conservation benefits the fear of them provides. Our experimental work demonstrated that fine-scale behavioural changes in prey in response to predation risk can have community-level effects relevant to biodiversity conservation. However, experimentally testing animal responses to predators and other sources of risk in free-living wildlife presents considerable logistical challenges. To address these challenges, my collaborators and I developed an Automated Behavioural Response system, which integrates playback experiments into camera trap studies, allowing researchers to collect experimental data from wildlife populations without requiring the presence of an observer. Here I describe tests of this system in Uganda, Canada and the USA, and discuss novel research opportunities in ecology and conservation biology made available by this new technology. / Graduate

Humans affect ecosystems by changing species compositions, landscape and climate. This thesis aims to increase our understanding of anthropogenic effects on mesopredator abundance due to changes in apex predator status, landscape and climate. I show that in Eurasia the abundance of a mesopredator, the red fox (Vulpes vulpes), is limited top-down by the Eurasian lynx (Lynx lynx) and bottom-up by winter severity. However, where lynx has been eradicated, fox abundance is instead related to bottom-factors such as cropland (paper I, II). Fox abundance was highest when croplands constituted 25% of the landscape (paper II). I also project red fox abundance in Sweden over the past 200 years and in future scenarios in relation to lynx density, land use and climate change. The projected fox abundance was highest in 1920, when lynx was eradicated and the proportion of cropland was 22%. In 2010, when lynx had recolonised, the projected fox abundance was lower than in 1920, but higher than in 1830. Future scenarios indicated that lynx abundance must increase in respond to climate change to keep fox at the same density as today. The results suggest a mesopredator release when lynx was eradicated, boosted by land use and climate change, and that changes in bottom-up factors can modify the relative strength of top-down factors (paper IV). From 1846-1922, lynx, wolverine (Gulo gulo) and grey wolf (Canis lupus) declined in Scandinavia due to persecution; however I show that the change in wolverine abundance was positively related to the changes in lynx and wolf abundance. This indicates that wolverine is subsidized by carrions from lynx and wolf kills rather than limited top-down by them (paper III). This thesis illustrates how mesopredator abundance is determined by a combination of top-down and bottom-up processes, and how anthropogenic impacts not only can change the structures of predator guilds, but also may modify top-down processes through changes in bottom-up factors. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted. Paper 4: Manuscript.</p><p> </p>

Predadores de topo desempenham um papel importante na manutenção dos sistemas em que eles ocorrem porque influenciam diretamente a estrutura e a dinâmica de comunidades. Desta forma, este estudo descreveu alguns mecanismos de co-ocorrência espaço-temporal entre a onça-pintada (Panthera onca) e duas espécies de mesopredadores (Puma concolor e Leopardus pardalis), o seu controle top-down na comunidade de mamíferos e os requerimentos ambientais que determinam a sua distribuição no bioma Amazônia. Para as análises de co-ocorrência espaço-temporal foram utilizados o modelo de ocupação e a densidade de Kernel utilizando os registros de armadilhamento fotográfico (2008-2011). Para descrever o controle top-down foi elaborada uma rede trófica utilizando os itens alimentares consumidos pelas espécies e disponíveis na literatura (1983-2014). Para indicar quais as áreas mais adequadas foi utilizado o modelo de distribuição de espécies utilizando as localizações geográficas de ocorrência da espécie que foram compiladas de três diferentes bases de dados (2000-2013). A ocorrência das duas espécies de mesopredadores não foi diferente nos sítios com e sem a onça-pintada nas quatro temporadas de amostragem. A probabilidade de detecção da jaguatirica foi maior nos sítios com a presença da onça-pintada em apenas uma temporada de amostragem. A sobreposição no período de atividade das espécies de mesopredadores com a onça-pintada foi baixa, com cerca de 55% de sobreposição. Também ocorreu uma mudança razoável no período de atividade das espécies entre as temporadas de amostragem, com mínima de 32% e máxima de 56% de sobreposição. As maiores diferenças na detecção e na sobreposição temporal ocorreram na terceira temporada quando teve o maior número de capturas e recapturas da onça-pintada. A rede trófica apresentou seis níveis e grande riqueza de espécies e densidade de interações. Após a remoção da onça-pintada, houve a perda de um nível trófico e de aproximadamente 20% de interações. Quando comparada a distribuição atual da onça-pintada com a histórica, foi possível constatar a perda de espaço ambiental em áreas mais frias (< 6,3 °C), mais secas (< 288 mm), mais úmidas (> 7517 mm) e com maior elevação (> 3597 m). O modelo de distribuição também indicou que muitas áreas potenciais estão disponíveis à ocorrência da onça-pintada e que algumas merecem atenção, especialmente, nas porções leste e sul da Amazônia onde a espécie corre maior risco de desaparecimento local devido à antropização acelerada. Este estudo forneceu significativa contribuição para a compreensão da população de onça-pintada na Amazônia, bioma que ainda possui a maior lacuna de conhecimento sobre a biologia e ecologia da espécie. Demonstrou o efeito da sua presença na detectabilidade e no período de atividade de outras espécies. Também demonstrou seu papel ecológico como predador de topo exclusivo porque foi a única espécie que predou todas as outras de níveis tróficos inferiores. Descreveu o espaço ambiental originalmente ocupado (distribuição histórica) e o perdido (distribuição atual). Indicou as áreas mais adequadas à sua ocorrência e aquelas potenciais ao seu desaparecimento. / Apex predators play an important role in the maintenance of systems in which occur because they directly influence the structure and dynamics of communities Thus, this thesis aims to describe some of the mechanisms of spatio-temporal co-occurrence between the jaguar (Panthera onca) and mesopredators (Puma concolor and Leopardus pardalis), their top-down control on the community and environmental requirements that determine their distribution. To the analyses of spatio-temporal co-occurrence were used the occupancy model and the Kernel density with records derived from camera trapping (2008-2011). To the analysis of trophic networks was used a foodweb model with prey spectra of felids compiled from the available literature (1983-2014). To indicate the most suitable areas to its occurrence was used a species distribution model with geographic location of the species compiled from three different databases. The occupation of the two species of mesopredators was not different among sites with and without jaguar. The probability of detection was different for ocelot, with higher detection on sites with than without jaguar. The overlap in the activity pattern among jaguar and mesopredators was low, with approximately 55% of overlapping. Also there was a reasonable change in the overlap between sampling seasons, with a minimum of 32% and maximum of 56% of the difference in the activity pattern. The differences in the detection and temporal overlap occurred in the third season when occurred the highest number of jaguar captures and recaptures. The trophic network presented six levels and, a high species richness and links density. After removal of the jaguar, a trophic level and approximately 20% of links were lost. When compared historical and current distributions, the loss of environmental space occurred in areas colder (< 6.3 ° C), drier (< 288 mm), wetter (> 7517 mm) and at higher elevation (> 3597 m). The distribution model also indicated that there is many potential suitable areas available to the jaguar occurrence and, some of them deserve attention, particularly, in eastern and southern portions of Amazonia where the species is most at risk of local extinction. This study provided a significant contribution to the knowledge of the population of jaguar in the Amazon biome which still has the largest gap of information on the biology and ecology of the species. It demonstrated the effect of the presence of the species in the detectability and the activity pattern of others. Also, it demonstrated their ecological role as an apex predator exclusive because it was the only one that ate all other species of lower trophic levels. It described the environmental space originally occupied (historical distribution) and lost (current distribution). It indicated potential suitable areas to its occurrence and threatened areas to its disappearance.

Many space probes have conducted in situ explorations of asteroids, in recent decades, intent on identifying evidence of the solar system's earliest processes of formation within the asteroids' interiors. Several future asteroid missions are planned, among which include ESA's Hera mission to explore the Didymos binary asteroid pair. An ion mass analyzer is currently being designed at the Swedish Institute of Space Physics for use as part of the Hera mission. This thesis aims to optimize the instrument such that each of its parameters meets the requirement for performance. A computer simulation is used to calculate the trajectories of low-energy ions inside the instrument, where the electrostatic potential are imposed by grids and electrodes embedded inside the instrument. From the data analysis of the simulation results, the performance for each parameter can be derived. By changing the settings of the grids and electrodes (e.g., positions and voltages), the instrument parameters are to be optimized. Two tasks are set up in this project--- the first task is to optimize the focusing system of the incoming ions at the instrument's entrance, and the second task is to investigate the reflectron system so that the mass resolution of the instrument can be optimized via reducing the spread of the ions' time of flight spectra. The focusing system is found to already be optimized, but instead, a relation between its position of the grid at the instrument's entrance and the instrument's performance is derived. The method of and parameters for optimization within the reflectron are extensively tested individually during this project. Although several performances in each trial from the reflectron analysis cannot meet at least one of the requirements, enough scenarios are examined such that every parameter tested ends with a value suitable to be applied individually to optimize the ion mass analyzer. The findings from the individual tests done in this project can be applied to further optimization, particularly to optimize multiple parameters simultaneously in the near future.

Le caféier Coffea arabica var. Laurina, aussi appelé Bourbon Pointu, est apparu à la Réunion suite à une mutation spontanée de la variété Bourbon. Cette mutation Laurina, monolocus et récessive, a des effets pléiotropiques qui différencie le Bourbon pointu du Bourbon. Au niveau morphologique, elle se caractérise par un nanisme, un port pyramidal et une forme pointue de ses graines. A un niveau moléculaire, la teneur des grains en caféine est fortement réduite. Malgré des caractéristiques agronomiques d'intérêt et d'excellentes qualités organoleptiques, peu d'études sont disponibles sur ce mutant naturel. Ce travail a ainsi pour objectif d'étudier la mutation Laurina et d'en caractériser les effets afin de mieux décrire les cascades de réaction mises en place. Il se base sur la comparaison du Bourbon pointu avec sa variété parente Bourbon. Au niveau morphologique, des mesures de croissance végétative ont permis l'analyse et l'explication de la forme pyramidale du mutant. Au niveau histologique, l'étude de l'apex, centre initiateur des organes de surface, et de différents entre-noeuds de l'axe orthotrope a permis d'expliquer l'origine du nanisme en terme de division et d'élongation cellulaire. Des hypothèses quant à l'action de la mutation Laurina sur certaines hormones ont été émises à partir des résultats d'application de gibbérelline exogène. Ces études macro et microscopiques ont été couplées au niveau moléculaire à la recherche de gènes différentiellement exprimés entre les deux variétés. La comparaison des transcriptomes des deux variétés à un stade précoce post-cotylédonaire avait pour but la recherche de gènes candidats impliqués dans les premières cascades de réactions menant aux effets pléiotropiques observés. Le clonage différentiel basé sur la méthode SSH (Hybridation Suppressive Soustractive) couplé à une étape de tri à haut débit (macro-array) a été appliqué à ces fins. L'ensemble des résultats décrit plus précisément les effets pléiotropiques induits par la mutation Laurina. La description précise des effets pléiotropiques de la mutation ouvre des pistes quant à la caractérisation moléculaire de la mutation à travers une approche gène candidat.

<p>About 70% of the plant species in the temperate zone are characterised by clonal growth, clonal species are also in majority in the Arctic and Subarctic where they affect the structure and composition of the vegetation. It is therefore of great importance to increase our knowledge about clonal plants and their growth and life histories. I have investigated how ramets of the stoloniferous plant <i>Linnaea borealis</i> are affected by the naturally occurring variation in environmental factors, such as: light, nutrient and water availability. Moreover, I examined the seed set and how supplemental hand pollination affects seed set in <i>L. borealis</i>, and also investigated the significance of the apical meristem for shoot population fitness. All studies were performed under field conditions in northern Sweden in a Subarctic environment and most are experimental.</p><p>The results show that nutrient resorption from senescing leaves is not significantly affecting the growth and nutrient pools of the ramet. This implies that the growth of<i> L. borealis </i>ramets is not governed by micro-site resource availability. However, removal of light competition resulted in increased branching and number of lateral meristems produced, reduced growth, and decreased root:shoot ratio on a per ramet basis. Thus, ramets of <i>L. borealis </i>can efficiently exploit favourable light patches through plastic growth. Apical dominance exerts a significant effect on shoot population fitness and can be lost through rodent grazing. However, loss of apical dominance is dependent on the timing of grazing, if the apical meristem is removed early in the autumn the ramet can repair the loss until the next summer. If grazing occur during spring the dry weight and leaf area production is affected negatively. Seed production in <i>L. borealis</i> in the Abisko area varies between years and sites, and was unaffected by supplemental hand pollination treatment, implying that there is no lack of pollinator activity.</p>

About 70% of the plant species in the temperate zone are characterised by clonal growth, clonal species are also in majority in the Arctic and Subarctic where they affect the structure and composition of the vegetation. It is therefore of great importance to increase our knowledge about clonal plants and their growth and life histories. I have investigated how ramets of the stoloniferous plant Linnaea borealis are affected by the naturally occurring variation in environmental factors, such as: light, nutrient and water availability. Moreover, I examined the seed set and how supplemental hand pollination affects seed set in L. borealis, and also investigated the significance of the apical meristem for shoot population fitness. All studies were performed under field conditions in northern Sweden in a Subarctic environment and most are experimental. The results show that nutrient resorption from senescing leaves is not significantly affecting the growth and nutrient pools of the ramet. This implies that the growth of L. borealis ramets is not governed by micro-site resource availability. However, removal of light competition resulted in increased branching and number of lateral meristems produced, reduced growth, and decreased root:shoot ratio on a per ramet basis. Thus, ramets of L. borealis can efficiently exploit favourable light patches through plastic growth. Apical dominance exerts a significant effect on shoot population fitness and can be lost through rodent grazing. However, loss of apical dominance is dependent on the timing of grazing, if the apical meristem is removed early in the autumn the ramet can repair the loss until the next summer. If grazing occur during spring the dry weight and leaf area production is affected negatively. Seed production in L. borealis in the Abisko area varies between years and sites, and was unaffected by supplemental hand pollination treatment, implying that there is no lack of pollinator activity.

Made available in DSpace on 2014-06-11T19:33:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-02-10Bitstream added on 2014-06-13T20:44:33Z : No. of bitstreams: 1 murata_ss_dr_araca.pdf: 3025122 bytes, checksum: d6ebabe611a7dce5412ed2e2cf0535db (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A dentição decídua é passível de ser acometida por traumatismos, lesões cariosas precoces (cárie de mamadeira) ou outro tipo de injúria, que podem comprometer a vitalidade pulpar desses dentes, inclusive com rizogênese incompleta. A escassez de trabalho específico sobre o assunto, bem como a importância de solucionar adequadamente esse tipo de problema, em dentes decíduos com rizogênese incompleta, estimulam a realização de investigações sobre o assunto. Portanto, o objetivo deste estudo foi avaliar, histologicamente, a resposta dos tecidos apicais e periapicais de dentes decíduos de cães, com rizogênese incompleta, após biopulpectomia e obturação dos canais radiculares com hidróxido de cálcio em diferentes veículos. Assim, os canais radiculares de 80 dentes decíduos anteriores de 6 cães da mesma ninhada, com 50 dias de idade, e com rizogênese incompleta, foram empregados neste estudo. Após o preparo biomecânico, os canais radiculares foram obturados com os seguintes materiais: Grupo 1- pasta Vitapex (hidróxido de cálcio, iodofórmio e óleo de silicone), Grupo 2- hidróxido de cálcio acrescido de iodofórmio e soro fisiológico, Grupo 3- hidróxido de cálcio associado ao Lipiodol e, Grupo 4 - controle - dentes com canais preparados e não obturados. Trinta dias após o tratamento, os animais foram mortos e os espécimes preparados para análise histomorfológica. A análise estatística dos resultados permitiu que os materiais estudados fossem ordenados do melhor para o pior resultado da seguinte forma: a) hidróxido de cálcio acrescido de iodofórmio e soro fisiológico, b) pasta Vitapex (hidróxido de cálcio acrescido de iodofórmio e óleo de silicone), c) hidróxido de cálcio associado ao lipiodol, d) controle. / The deciduous teeth with open apex are susceptible to be traumatized by carious lesions or other offence type that can engage the pulp vitality of those teeth. The lacking of specific work on the subject, as well as the importance of solving this kind of problem appropriately stimulates the accomplishment of investigations on the subject. Therefore, the subject of this study was to evaluate, histologically, the behavior of apical tissues of deciduous dogs teeth with open apex, after biopulpectomy and root canal filling with calcium hydroxide in different vehicles. The root canals of 80 deciduous teeth, from 6 dogs of the same hatch, with 50 days of age, and with open apex, were used in this study. After the biomechanical preparation, the root canals were filled with the following materials: Vitapex - calcium hydroxide added to iodoform and silicon oil; paste of calcium hydroxide with iodoform and saline; paste of calcium hydroxide with lipiodol, and as control group, teeth with root canal prepared but not filled. Thirty days after the treatment, the animals were killed and the specimens were prepared for histomorphological analysis. The statistical analysis of the results allowed the studied materials to be ordered from the best to the worst in the following way: a) calcium hydroxide added to iodoform and saline, b) Vitapex - calcium hydroxide added to iodoform and silicon oil, c) calcium hydroxide added to Lipiodol, d) control. It was observed statistical significant difference (p=0.05) among the results of the groups of calcium hydroxide associated to iodoform and saline with the calcium hydroxide group associated to lipiodol, as well as the 3 groups filled with calcium hydroxide pastes with the control group (p=0.001). It was concluded that the 3 pastes of calcium hydroxide studied can be used as root canal filling material in the treatment of deciduous teeth with open apex.