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Eucalyptus DREB regulation pathway : control of abiotic stress tolerance, plant development and wood formation / Contribution à l'étude de la régulation de la voie des facteurs de transcription DREB chez l'eucalyptus : contrôle de la tolérance aux stress abiotique, de la croissance et de la formation du boisNguyen, Hong Chien 26 September 2016 (has links)
L'Eucalyptus, feuillu le plus planté dans le monde, est fortement exposé au froid en raison de l'absence de dormance. Les gènes DREB sont connus comme étant les principaux régulateurs de la réponse aux stress abiotiques. Un nombre élevé de gènes DREB1/CBF (C-Repeat Factor) a été identifié chez Eucalyptus grandis. Le but de l'étude est de mieux comprendre le rôle de la voie DREB chez Eucalyptus pour le contrôle de la tolérance au stress, du développement et de la formation du bois. La présente étude a permis une annotation des gènes CBF et DREB2 dans le cadre d'un projet de sequençage partiel du génome d'E. gunnii. Une analyse complète de l'expression des genes par qRT-PCR a été réalisée sur les différents organes des deux espèces d'Eucalyptus après les traitements au stress. L'existence d'une copie de CBF supplémentaire dans le génome E. gunnii par rapport à E. grandis suggère que ce groupe est encore en évolution contrairement au groupe DREB2. Un nombre élevé de transcrits CBF chez E. gunnii, tolérant au froid, et forte une vitesse d'induction ce ces facteurs chez E. grandis, à croissance rapide, suggère que les facteurs CBF sont impliqués à la fois dans la protection au stress et la limitation de croissance. Des facteurs de transcription des familles MYB, NAC, KNOX et AP2/ERF impliqués dans le contrôle de la croissance et de la formation de la paroi cellulaire ont été identifiés comme étant des gènes putatifs cibles de CBF. Ces résultats sont en accord avec le phénotype modifié de surexpresseurs CBF. Les deux approches suggèrent un rôle central de la voie de DREB dans le compromis entre la croissance et la résistance au stress chez cette espèce ligneuse. / Eucalyptus, the most widely planted hardwood in the world, is highly exposed to the cold due to the lack of dormancy. DREB (Drought Responsive Element Binding) genes are known as master regulators of abiotic stress response. A high number of the DREB1/CBF (C-Repeat Factor) genes has been annotated in Eucalyptus grandis. The aim of the study was to better understand the role of DREB pathway in Eucalyptus for the control of stress tolerance, development and wood formation. The present study provides an annotation of the CBF and DREB2 genes from a partial draft of the E. gunnii genome sequence. A comprehensive transcriptional analysis through high-throughput qRT-PCR was carried out on different organs from the two Eucalyptus species after stress treatments. An additional CBF copy in the E. gunnii genome compared to E. grandis suggests that this group is still evolving unlike the DREB2 group. The higher CBF transcript amounts in the cold tolerant E. gunnii together with higher induction rates in the fast growing E. grandis suggest that CBF factors promote both stress protection and growth limitation. In addition, transcription factors from MYB, NAC, KNOX and AP2/ERF families involved in the control of growth and cell wall formation have been identified as putative CBF target genes. These results are in agreement with the modified phenotype of CBF overexpressors. Both approaches suggest a central role of DREB pathway in the trade-off between growth and stress resistance in this woody species.
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How do herbivorous mammals adjust their trade-off between food and safety ? / Comment les mammifères herbivores ajustent leur compromis entre acquisition des ressources alimentaires et détection des prédateurs ?Favreau, Francois-René 10 July 2014 (has links)
Afin d'accroître leur survie et leur succès reproducteur, les espèces proies tentent de maximiser leur apport énergétique tout en évitant la prédation, induisant un compromis entre acquisition des ressources alimentaires et détection des prédateurs. Cependant, les ajustements comportementaux des herbivores impliqués dans ce compromis peuvent être influencés par de nombreux paramètres environnementaux, sociaux et individuels et varier entre individus d'une population. Ce travail de thèse a pour objectif de mieux comprendre comment les herbivores proies ajustent leur compromis entre vigilance et approvisionnement en fonction du risque de prédation, du contexte social et de la disponibilité des ressources ; ainsi que d'étudier si ces ajustements varient entre individus. Basées sur l'étude de femelles kangourous gris de l'Est (Macropus giganteus) et de femelles impala (Aepyceros melampus), j'ai tout d'abord observé que bien que de nombreux facteurs influençaient la vigilance et l'approvisionnement à court terme, ces comportements étaient principalement influencés par la variation de la ressource à long terme. Ensuite, j'ai démontré que les variations de contextes écologiques et sociaux tels que le risque de prédation, la ressource alimentaire et la compétition induisaient des réponses comportementales différentes au regard de ce compromis, ainsi que sur la fonction et le coût de la vigilance. Enfin, j'ai observé l'existence de variations entre individus, plus ou moins exprimées dans différentes conditions. Il apparaît que les animaux régulent leur activité de vigilance afin de maximiser l'acquisition de ressources, ou d'informations sociales, tout en assurant leur sécurité / Prey species foraging under a risk of predation have to trade between food acquisition and safety from predation in order to increase their fitness. This trade-off is commonly investigated by studying the trade-off between foraging and vigilance activities. However, vigilance and foraging can be affected by numerous environmental, social, and individual parameters which can also vary seasonally and differ between individuals from the same population. In this context, the overall objective of my PhD was to better understand how herbivorous prey animals manage the feeding/vigilance trade-off at a fine scale, considering the wide range of variables that may affect it, individual variation, and the different functions of vigilance, using female eastern grey kangaroos (Macropus giganteus) and impalas (Aepyceros melampus) as models. I observed that despite the many factors that shape vigilance and feeding rates over short time scales, these behaviours were mainly driven by variation in food resources over longer temporal scales. I also highlighted that predator and social contexts induced different behavioural responses in relation to this trade-off, and that decisions of prey to adjust their vigilance in terms of function and cost were driven by predation risk, food availability, and competition but varied between seasons. Finally, I observed that between-individual variation occurs for this trade-off but that this variation is context dependant. This thesis shows that prey animals constantly adapt their behaviour and strategies according to the situation they experience, in order to balance the acquisition of food and social information with staying safe
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Task Complexity (‘Here-and- Now’ Dimension) and Written Performance across Proficiency LevelsKalamakis, Sara Zoi January 2019 (has links)
Research on task-based language teaching (TBLT) offers a large body of evidence suggesting that cognitive task complexity influences learners’ language production and development. Studies that investigate task complexity, however, provide contradictory results on the way different linguistic aspects of performance are affected by the manipulation of cognitive task complexity. The empirical study presented in this degree project aimed to investigate the effect of task complexity on the accuracy, complexity and fluency in learners ́ written performance. An additional goal of the study was to examine whether proficiency level would mediate the effects of cognitive task complexity. In order to explain the influence of cognitive task complexity on linguistic performance two theoretical models are used and discussed, namely Skehan’s Limited Attention Capacity Hypothesis (Skehan 2015) and Robinson’s Cognition Hypothesis (Robinson 2001, 2011, 2015). In order to answer the research questions guiding the study, 71 Swedish high school students of Spanish performed a simple or a more cognitively complex version of a written task. Results showed that increasing task complexity had a positive effect on the fluency, accuracy, and complexity of the participants ́ written performance, and that these effects were greater among the high proficiency participants’ productions. These results offer valuable implications for syllabus and task designers, language teachers and examiners, as well as second and foreign language researchers.
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The Impact of COVID-19 on Corporate Capital Structure : An empirical evaluation on the pandemic in a Swedish contextEdberg, Christopher, Kjellander, Oliver January 2022 (has links)
This study has strived to explore how capital structure in Swedish corporations has been affected by the COVID-19 pandemic. The study has employed both a panel regression with fixed and random effects estimation as well as a dynamic panel regression with Arellano-Bond estimators. The model utilizes common and appropriate capital structure determinants to investigate how leverage has changed between a pre-crisis and crisis sample. Even though the results have proven to be relatively scattered they have indicated that corporate leverage has increased in the crisis period. Furthermore, this study examined how corporate size (market capitalization) and industry has impacted the capital structure. The results suggest that industries such as consumer goods and services have experienced a higher degree of influence in comparison to industries such as healthcare. The evidence also suggests several significant relationships such as between tangibility and leverage as well as an overall general inclination towards the Pecking-Order Theory. Additionally, the rate of adjustment of the corporate leverage prior to the crisis was comparable to that of the 2007/08 financial crisis, but did ultimately not undergo a dramatic change similar to the financial crisis found in previous research. / Denna studie ämnade att undersöka och utvärdera hur kapitalstrukturen i Svenska bolag har påverkats av COVID-19 pandemin. Studien har tillämpat en panelregression med både fixed och random effects, samt en dynamisk panelregression med den applicerbara Arellano-Bond skattnings estimatorn. Modellerna använder sig av vedertagna och lämpliga variabler för att härleda hur belåningsgraden har utvecklats mellan period före pandemin samt under pandemin. Även om resultaten har varit relativt spridda har de ändå indikerat att belåningsgraden har ökat under pandemin. Utöver detta har studien undersökt hur belåningsgraden har påverkats som en funktion av bolagsstorlek (baserat på börsvärde) samt den industri som bolaget verksam i. Resultaten tyder på att industrier som konsumtionsvaror och tjänster (consumer goods and services) har påvisat en större påverkan jämfört med industrier som sjukvård. Resultaten finner att variabeln tangibility har en stor del signifikanta värden och att den finner stöd hos den så kallade Pecking-Order teorin. Studien har även kommit fram till att anpassningshastigheten av belåningsgraden innan krisen var jämförbar med samma värde innan finanskrisen 2007/08, dock förblev anpassningshastigheten relativt oförändrad av pandemin i jämförelse till finanskrisen.
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Capital structure and stock return : A quantitative study of the relationship between leverage and stock return on Swedish listed firmsÅberg, Erik, Andersson, Philip January 2022 (has links)
This study investigates the effect of leverage on stock returns on Swedishlisted firms (Large and Mid-cap). Stock returns have been calculated, andleverage ratios have been collected through Datastream. The results contradictfundamental theories on capital structure. According to the fundamentaltheories there should be a positive relationship, but the result of this studysuggests that the relationship is negative.
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Multi criteria decision making approach for strategic evaluation of environmental trade-off solution in logistics : A case study at NorthvoltHedgren, Amanda, Genberg, Daniel January 2021 (has links)
The purpose of this thesis is to investigate to what extent the environmental agenda should be taken into consideration during the project phase of logistics at Northvolt. The objective is to build an optimization model for route planning with a trade-off solution for three criteria; cost, emission and time. An abductive research approach is used. The empirical data was collected quantitatively in accordance with cross-industry standard process for data mining. The results obtained from the optimization model were based on an emission calculation framework and weights assigned to the three selected criteria by five decision makers. These results are compared to an as-is analysis of current and of historical transportations as well as to expected future transportations. These results provide insights and emphasize the importance of agility in decision making aiming at the reduction of emissions. The analysis shows that increased costs do not have a clear correlation with reduced emissions or transportation time. It also demonstrates that transporting goods on sea would increase the transportation time but decrease the emissions. The conclusions of the study are that costs can be reduced by 8%, emissions by 6% and transportation time by 14%, compared to their current operations. Short-term recommendations address the need of being agile in the route planning and analyse each shipment individually where the weights of the criteria should be alternated depending on the status of the project. This requires increased communication with the installation team on site and negotiation of contractual rates from additional ports in Sweden. Long-term recommendations emphasise the importance of developing and using emission key performance indicators to set targets in combination with a strategy in order to steer daily operations.
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Magisteruppsats : Lönsamhet, kapitalstruktur och dess påverkan på marknadsvärderingJohansson, Viktor, Werner, Douglas January 2021 (has links)
Title: Profitability, capital structure and its impact on market valuation Background: Capital structure is a topic that financial research has focused a lot on and there are several theories about how companies act and should act with the mix of equity and liabilities in their financing. The continued research on the role of the capital structure and its impact on companies has found that the capital structure has a clear impact on companies' cost of capital, which affects the market valuation of companies. Purpose: The study has two sub-purposes. The first sub-objective is to study the effect of profitability on the debt-to-equity ratio. The second is to analyze the effect of the debt-to-equity ratio on the market valuation. Method: The method in the study is a cross-sectional study with a deductive approach. The hypotheses in the first sub-purpose of the study have been formulated with the help of the Tradeoff theory, the pecking order theory, and previous research. The hypotheses in the second sub-purpose of the study have been formulated with the help of the signaling of debt theory. Conclusion: The results of the study find an indication that profitability has an impact on the debt-to-equity ratio and that the pecking order theory tends to have a better explanatory effect regarding the relationship between the two. And that the loan-to-value ratio has no significant effect on the market valuation. Keywords: Capital structure, financial leverage, debt-to-equity ratio, profitability, market value, Trade-off Theory, Pecking Order Theory, Signaling of debt Theory
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Ledningens karaktärsdrag - effekten på kapitalstruktur : En studie om förhållandena mellan tre individuella chefers karaktärsdrag och företags hävstångSvanberg, Mikaela, Lilliestrand, Johan January 2020 (has links)
Titel: Ledningens karaktärsdrag - effekten på kapitalstrukturEn studie om förhållandena mellan tre individuella chefers karaktärsdrag och företagshävstång Bakgrund och problematisering: Här diskuteras bakgrunden till studien och enproblematisering kring chefers karaktärsdrag och dess påverkan på kapitalstruktur samt vadsom menas med dessa begrepp. Vidare tar detta kapitel upp det underliggande intresset attförklara sambandet mellan tre chefers karaktärsdrag (CEO, CFO och COO) ochkapitalstruktur. Syfte: Syftet med denna studie är att förklara effekten av individuella chefers karaktärsdragpå svenska börsnoterade företags kapitalstruktur. Metod: Företagens kapitalstruktur undersöks genom att använda en kvantitativforskningsmetod med en deduktiv forskningsansats för att identifiera förhållanden mellanchefernas karaktärsdrag och hävstång. Paneldata används från 114 svenska börsnoteradeföretag över en femårsperiod (2014-2018). Studien fann totalt 179 chefer varav 87 CEO:s, 73CFO:s och 19 COO:s. Den insamlade datan testas genom regressionsanalyser där paneldataregressioner med random effects-modellen och robusta standardfel utförs. Slutsats: Resultaten från testerna visar på både signifikanta och icke-signifikantaförhållanden mellan de tre chefernas karaktärsdrag och företagens kapitalstruktur, mätt somhävstång. Det finns därmed bevis som tyder på att olika karaktärsdrag hos individuella cheferpåverkar företags kapitalstruktur.
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Likviditetens betydelse för lönsamhet : En kvantitativ studie på svenska småföretagGummesson, Malin, Slaveska, Martina January 2021 (has links)
Liquidity and profitability are both vital aspects of a company's survival. Earlier studies suggest that there is a trade-off between liquidity and profitability. Too much liquidity can lower the profitability but the company still needs to maintain sufficient liquidity in order to be able to meet their short-term obligations. The aim of this study is to contribute to the understanding of the liquidity effect on profitability and the relationship between liquidity and profitability in swedish small companies. The relationship will be investigated with regards to industry and level of liquidity. The study is an empirical cross-sectional study where the main analysis method is multiple regression analysis.The results showed that there is a significant relationship between liquidity and profitability that appears to be non-linear. In the overall sample, there was a significant negative relationship between liquidity and profitability, measured as ROE and a positive relationship when profitability was measured as ROA. The results also reveal that with low liquidity levels (quick ratio below 2) the relationship between liquidity and profitability is positive, but the positive effect decreases and eventually disappears as the liquidity levels increase. The relationship is also more prominent in some industries, but not possible to distinguish in others. The model indicated that even though there was a significant relationship between liquidity and profitability, it only explained a small portion of the total variation in profitability.
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Modeling the speed-accuracy tradeoff using the tools of information theory / Modélisation du compromis vitesse précision d'une tâche de pointage humain à l'aide des outils de la théorie de l'informationGori, Julien 20 December 2018 (has links)
La loi de Fitts, qui relie le temps de mouvement MT dans une tache de pointage aux dimensions de la cible visée D et W est usuellement exprimée à partir d’une imitation de la formule de la capacité de Shannon MT = a + b log 2 (1 + D/W). Toutefois, l’analyse actuelle est insatisfaisante: elle provient d’une simple analogie entre la tache de pointage et la transmission d’un signal sur un canal bruité sans qu’il n’y ait de modèle explicite de communication.Je développe d’abord un modèle de transmission pour le pointage, où l’indice de difficulté ID = log 2 (1 + D/W) s’exprime aussi bien comme une entropie de source et une capacité de canal, permettant ainsi de réconcilier dans un premier temps l’approche de Fitts avec la théorie de l’information de Shannon. Ce modèle est ensuite exploité pour analyser des données de pointage récoltées lors d’expérimentations contrôlées mais aussi en conditions d’utilisations réelles.Je développe ensuite un second modèle, focalisé autour de la forte variabilité caractéristique du mouvement humain et qui prend en compte la forte diversité des mécanismes de contrôle du mouvement: avec ou sans voie de retour, par intermittence ou de manière continue. À partir d’une chronométrie de la variance positionnelle, évaluée à partir d’un ensemble de trajectoires, on remarque que le mouvement peut-être découpé en deux phases: une première où la variance augmente et une grande partie de la distance à couvrir est parcourue, est suivie d’une deuxième au cours de laquelle la variance diminue pour satisfaire les contraintes de précision requises par la tache.Dans la deuxième phase, le problème du pointage peut-être ramené à un problème de communication à la Shannon, où l’information est transmise d’une“source” (variance à la fin de la première phase) à une “destination” (extrémité du membre) à travers un canal Gaussien avec la présence d’une voie de retour.Je montre que la solution optimale à ce problème de transmission revient à considérer un schéma proposé par Elias. Je montre que la variance peut décroitre au mieux exponentiellement au cours de la deuxième phase, et que c’est ce résultat qui implique directement la loi de Fitts. / Fitts’ law, which relates movement time MTin a pointing task to the target’s dimensions D and Wis usually expressed by mimicking Shannon’s capacityformula MT = a + b log 2 (1 + D/W). Yet, the currentlyreceived analysis is incomplete and unsatisfactory: itstems from a vague analogy and there is no explicitcommunication model for pointing.I first develop a transmission model for pointing taskswhere the index of difficulty ID = log 2 (1 + D/W) isthe expression of both a source entropy and a chan-nel capacity, thereby reconciling Shannon’s informa-tion theory with Fitts’ law. This model is then levera-ged to analyze pointing data gathered from controlledexperiments but also from field studies.I then develop a second model which builds on thevariability of human movements and accounts for thetremendous diversity displayed by movement control:with of without feedback, intermittent or continuous.From a chronometry of the positional variance, eva-luated from a set of trajectories, it is observed thatmovement can be separated into two phases: a firstwhere the variance increases over time and wheremost of the distance to the target is covered, follo-wed by a second phase where the variance decreasesuntil it satisfies accuracy constraints. During this se-cond phase, the problem of aiming can be reduced toa Shannon-like communication problem where infor-mation is transmitted from a “source” (variance at theend of the first phase), to a “destination” (the limb ex-tremity) over a “channel” perturbed by Gaussian noisewith a feedback link. I show that the optimal solution tothis transmission problem amounts to a scheme firstsuggested by Elias. I show that the variance can de-crease at best exponentially during the second phase,and that this result induces Fitts’ law.
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