Made available in DSpace on 2016-06-02T19:05:52Z (GMT). No. of bitstreams: 1 3803.pdf: 3743774 bytes, checksum: 49431d1966e0013e1955f7cb03a6cf70 (MD5) Previous issue date: 2011-04-14 / Financiadora de Estudos e Projetos / The raising number of mobile devices with high computing capacity and support to different wireless transmission technologies has been motivating the creation of communication services capable to provide information to users anytime and anywhere. Particularly, it s possible to note the existence of a massive number of devices equipped with the Bluetooth communication technology, available in millions of devices. Plenty of mechanisms for content dissemination and sharing have been developed for use with Bluetooth technology in different application scenarios, such as mobile marketing, u-commerce and mobile learning. Most of these mechanisms, however, are used for specific purposes or are highly dependent on a communication infrastructure. Moreover, most of them use only little information about different contexts related to the environment, the users and the state of the devices involved in the transmissions. This work presents the project and a feasibility analysis of a context-aware communication platform that enables the delivery of data to mobile devices. Different types of information may be delivered, as produced by the execution of services which generate or retrieve them prior to transmission. Transmissions to the devices occur via wireless communication technologies, especially the Bluetooth. Called BlueYou, this platform makes use of context information and the profiles of mobile device to set policies for content delivery and content adaptation. Moreover, in order to expand the access to the services that generate the contents to deliver by BlueYou, the platform is integrated with a communication mechanism that creates an opportunistic ad hoc networking between mobile devices to transmit data to a particular recipient. As a result, it is expected that BlueYou can be widely used without requiring high deployment costs (financial, technological or time), and can serve as a basis for future studies involving communication patterns and interaction between users of mobile technologies. / O crescente número de dispositivos móveis com capacidade computacional elevada e suporte a diferentes tecnologias de transmissão sem fio tem motivado a criação de serviços de comunicação capazes de fornecer informações aos usuários a qualquer momento e em qualquer lugar. Particularmente, nota-se a existência maciça de dispositivos equipados com a tecnologia de comunicação Bluetooth, disponível em bilhões de dispositivos. Diversos mecanismos para a disseminação e o compartilhamento de conteúdo foram desenvolvidos para serem utilizados com a tecnologia Bluetooth, em diferentes cenários de aplicação, tais como mobile marketing, ucommerce e mobile learning. A maioria desses mecanismos, contudo, atende a propósitos específicos ou é altamente dependente de uma infraestrutura de comunicação. Além disso, percebe-se que há pouco uso de informações sobre diferentes contextos relacionados ao ambiente, aos usuários e ao estado dos dispositivos envolvidos nas transmissões. Este trabalho apresenta o projeto e a análise de viabilidade de uma plataforma de comunicação ciente de contexto que possibilita o envio de informações para dispositivos móveis. Diferentes tipos de informação podem ser enviados, tais como informações produzidas por serviços, os quais realizam a geração ou a obtenção dos conteúdos a transmitir. Transmissões ocorrem através de tecnologias de comunicação sem fio, em especial a tecnologia Bluetooth. Denominada BlueYou, esta plataforma faz uso de informações de contexto e de uma base de dados de dispositivos móveis para definir políticas de entrega e de adaptação dos conteúdos que transmite. Além disso, visando a expandir o acesso aos serviços que geram os conteúdos a transmitir via BlueYou, a plataforma se integra com um mecanismo de comunicação oportunística que cria redes ad hoc entre dispositivos móveis para a transmissão de dados a destinatários específicos. Como resultado, espera-se que BlueYou seja uma plataforma que possa ser amplamente utilizada sem exigir altos custos de implantação, sejam eles financeiros, tecnológicos ou de tempo, e que possa servir de base para estudos futuros envolvendo padrões de comunicação e interação entre usuários de tecnologias móveis.

Our work focuses on wireless networks in general, but deals specifically with security in wireless sensor networks and energy consumption in IEEE 802.11 infrastructure WLANs. In the first part of our work, we focus on secure communication among sensor nodes in a wireless sensor network. These networks consists of large numbers of devices having limited energy and memory. Public key cryptography is too demanding for these resource-constrained devices because it requires high computation. So, we focus on symmetric key cryptography to achieve secure communication among nodes. For this cryptographic technique to work, two nodes have to agree upon a common key. To achieve this, many key distribution schemes have been proposed in the literature. Recently, several researchers have proposed schemes in which they have used group-based deployment models and assumed predeployment knowledge of the expected locations of nodes. They have shown that these schemes achieve better performance than the earlier schemes, in terms of connectivity, resilience against node capture and storage requirements. But in many situations expected locations of nodes are not available. We propose a solution which does not use the group-based deployment model and predeployment knowledge of the locations of nodes, and yet performs better than schemes which make the aforementioned assumptions. In our scheme, groups are formed after the deployment of sensor nodes on the basis of their physical locations. Nodes in different groups sample keys from disjoint key pools, so that compromise of a node affects secure links of its group only. Because of this reason, our scheme performs better than earlier schemes as well as the schemes using predeployment knowledge, in terms of connectivity, storage requirement, and security. Moreover, the post-deployment key generation process completes sooner than in schemes like LEAP+. In the second part of our work, we develop analytical models for estimating the energy spent by stations (STAs) in infrastructure WLANs when performing TCP-controlled file downloads. We focus on the energy spent in radio communication when the STAs are in the Continuously Active Mode (CAM), or in the static Power Save Mode (PSM). Our approach is to develop accurate models for obtaining the fractions of times the STA radios spend in idling, receiving and transmitting. We discuss two traffic models for each mode of operation: (i) each STA performs one large file download, and (ii) the STAs perform short file transfers with think times (short duration of inactivity)between two transfers. We evaluate the rate of STA energy expenditure with long file downloads, and show that static PSM is worse than using just CAM. For short file downloads, we compute the number of file downloads that can be completed with a given battery capacity, and show that PSM performs better than CAM for this case. We provide a validation of our analytical models using the NS-2 simulator. Although the PSM performs better than the CAM when the STAs download short files over TCP with think times, its performance degrades as the number of STAs associated to the access point (AP) increases. To address this problem, we propose an algorithm, which we call opportunistic PSM (OPSM). We show through simulations that OPSM performs better than PSM. The performance gain achieved by OPSM increases as the file size requested by the STAs or the number of STAs associated with the AP increases. We implemented OPSM in NS-2.33, and to compare the performance of OPSM and PSM, we evaluate the number of file downloads that can be completed with a given battery capacity and the average time taken to download a file.

Opportunistic selection and rate adaptation play a vital role in improving the spectral and power efficiency of current multi-node wireless systems. However, time-variations in wireless channels affect the performance of opportunistic selection and rate-adaptation in the following ways. Firstly, the selected node can become sub-optimal by the time data transmission commences. Secondly, the choice of transmission parameters such as rate and power for the selected node become sub-optimal. Lastly, the channel changes during data transmission. In this thesis, we develop a comprehensive and tractable analytical framework that accurately accounts for these effects. It differs from the extensive existing literature that primarily focuses on time-variations until the data transmission starts. Firstly, we develop a novel concept of a time-invariant effective signal-to-noise ratio (TIESNR), which tractably and accurately captures the time-variations during the data transmission phase with partial channel state information available at the receiver. Secondly, we model the joint distribution of the signal-to-noise ratio at the time of selection and TIESNR during the data transmission using generalized bivariate gamma distribution. The above analytical steps facilitate the analysis of the outage probability and average packet error rate (PER) for a given modulation and coding scheme and average throughput with rate adaptation. We also present extensive numerical results to verify the accuracy of each step of our approach and show that ignoring the correlated time variations during the data transmission phase can significantly underestimate the outage probability and average PER, whereas it overestimates the average throughput even for packet durations as low as 1 msec.

The human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) is a worldwide pandemic that affects the lives of millions of people across all ages. Its devastating effects are far-reaching and affect all aspects of an individual’s daily life. HIV/AIDS is responsible for widespread clinical manifestations involving the head and neck. Disorders of the auditory and vestibular systems are often associated with HIV/AIDS, however the extent and nature of these vestibular manifestations is still largely unknown. The main aim of this research study was to investigate vestibular functioning and pathology in adults with HIV/AIDS. This was achieved through three main research steps: a systematic literature review of the body of peer-reviewed literature on HIV/AIDS related vestibular manifestations and pathology, a description and comparison of vestibular involvement in adults with and without HIV/AIDS and an investigation to determine if HIV/AIDS influence the vestibulocollic reflex (VCR) pathways. For the first study a systematic literature review related to vestibular findings in individuals with HIV infection and AIDS was conducted. A varied search strategy was used across several electronic databases to identify relevant peer-reviewed reports in English. Several databases (Medline, Scopus and PubMed) and search strategies were employed. Where abstracts were not available, the full paper was reviewed, and excluded if not directly relevant to the study’s aims. Articles were reviewed for any HIV/AIDS associated vestibular symptoms and pathologies reported. For the second and third study, a cross-sectional, quasi-experimental comparative research design was employed. A convenience sampling method was used to recruit subjects. The sample consisted of 53 adults (29 male, 24 female, aged 23-49 years, mean = 38.5, SD = 4.4) infected with HIV, compared to a control group of 38 HIV negative adults (18 male, 20 female, aged 20-49 years, mean = 36.9, SD = 8.2). A structured interview probed the subjective perception of vestibular complaints and symptoms. Medical records were reviewed for cluster of differentiation 4+ (CD4+) cell counts and the use of antiretroviral (ARV) medication. An otologic assessment and a comprehensive vestibular assessment (bedside assessments, vestibular evoked myogenic potentials, ocular motor and positional tests and bithermal caloric irrigation) were conducted on all subjects. The systematic literature review identified 442 records, reduced to 210 after excluding duplicates, reviews, editorials, notes, letters and short surveys. These were reviewed for relevance to the scope of the study. There were only 13 reports investigating vestibular functioning and pathology in individuals affected by HIV/AIDS. This condition can affect both the peripheral and central vestibular system, irrespective of age and viral disease stage. Post-mortem studies suggest direct involvement of the entire vestibular system, while opportunistic infections such as oto- and neurosyphilis and encephalitis cause secondary vestibular dysfunction resulting in vertigo, dizziness and imbalance. The second study showed an overall vestibular involvement in 79.2% of subjects with HIV in all categories of disease progression, compared to 18.4% in those without HIV. Vestibular involvement increased from 18.9% in the Centers for Disease Control and Prevention (CDC) category 1 to 30.2% in category 2. Vestibular involvement was 30.1% in category 3. There was vestibular involvement in 35.9% of symptomatic HIV positive subjects and 41.5% in asymptomatic HIV positive subjects. Individuals with HIV were 16.6 times more likely to develop vestibular involvement during their lifetime, than among individuals without this disease. Vestibular involvement may occur despite being asymptomatic. The third study showed that abnormal cervical vestibular evoked myogenic potentials and caloric results were significantly higher in the HIV positive group (p=.001), with an odds ratio of 10.2. Vestibulocollic reflex and vestibulo-ocular reflex involvement increased with progression of the disease. There were more abnormal test results in subjects using ARV therapies (66.7%) compared to those not using ARV therapies (63.6%), but this difference was not statistically significant. Vestibular involvement was significantly more common in subjects with HIV than among those without this disease. This disease and its associated risk profile include direct effects of the virus on the vestibular system as demonstrated by postmortem studies. Opportunistic infections may compromise the functioning of the sensory and neural structures of hearing and the vestibular system indirectly, causing vertigo, dizziness or disequilibrium. Ototoxicity may also be related to vestibular dysfunction, due to the ototoxic nature of certain ARV medications. HIV/AIDS influence not only the vestibulo-ocular reflex, but also the vestibulocollic reflex pathways. Primary health care providers could screen HIV positive patients to ascertain if there are symptoms of vestibular involvement. If there are any, then they may consider further vestibular assessments and subsequent vestibular rehabilitation therapy, to minimize functional limitations of quality of life. / Thesis (DPhil)--University of Pretoria, 2014. / lk2014 / Speech-Language Pathology and Audiology / DPhil / Unrestricted

The basic goal of diploma thesis "The Propensity to Government Budget Deficit: Analysis of the Influence of Political Cycle on Czech Fiscal policy" is to identify fundamental factors which influence decisions about the size of government budget balance and to analyze the influence of political cycle on the volume and structure of government expenditures in the period of 1993-2009. Analysis is based on theories which are connected to the areas of public sector, state and its function, public finances, government budget, the process of generating budget, political cycle, political parties and europeanization. The problem of propensity to budget deficits is structured using dimensional analysis and problem tree. The influence of political cycle is verified by using the combination of qualitative analysis of policy documents and quantitative analysis of specific indicators. Analysis classifies external and internal factors influencing the tendency to deficit budgeting. Political cycle is one of those internal factors becouse it is affected by the decision making process of political representatives. The influence of political cycle on the volume of government expenditures and the expenditures of the Ministry of Labor and social affairs could not be demonstrated on data. Otherwise, there is possibility...

Les années récentes ont vu l’explosion du trafic sur les réseaux mobiles depuis l’apparition de nouveaux terminaux (smartphones, tablettes) et des usages qu’ils permettent, en particulier les données multimédia, le trafic voix restant sensiblement constant. Une conséquence est le besoin de plus de spectre, ou la nécessité de mieux utiliser le spectre déjà alloué. Comme il n’y a pas de coordination entre les utilisateurs secondaire(s) et primaire, avant toute transmission les premiers doivent mettre en œuvre des traitements pour détecter les périodes dans lesquelles l’utilisateur primaire transmet, ce qui est le scénario considéré dans cette thèse. Nous considérons donc une autre approche, reposant sur l’utilisation de codes correcteurs d’effacements en mode paquet. La dernière partie de la thèse aborde un scénario dans lequel il n’y a plus d’utilisateur primaire, tous les utilisateurs ayant le même droit à transmettre dans le canal. Nous décrivons une modification de la couche MAC du 802.11 consistant à réduire les différents temps consacrés à attendre (SIFS, DIFS, backoff, . . .) afin d’accéder plus souvent au canal, au prix de quelques collisions supplémentaires qu’il est possible de récupérer en mettant en œuvre des codes correcteurs d’effacements. / The emergence of new devices especially the smartphones and tablets having a lot of new applications have rocketed the wireless traffic in recent years and this is the cause of main surge in the demand of radio spectrum. There is a need of either more spectrum or to use existing spectrum more efficiently due to dramatic increase in the demand of limited spectrum. Among the new dynamic access schemes designed to use the spectrum more efficiently opportunistic spectrum access (OSA) is currently addressed when one or more secondary users (SU) are allowed to access the channel when the PU is not transmitting. The erasure correcting codes are therefore envisioned to recover the lost data due to sensing impairments. We define the parameter efficiency of SU and optimize it in-terms of spectrum utilization keeping into account sensing impairments, code parameters and the activity of PU. Finally, the spectrum access for multiple secondary users is addressed when there is no primary and each user has equal right to access the channel. The interesting scenarios are Cognitive radio networks and WiFi where 802.11 protocol gives the specification for MAC layer. The throughput curvesachieved by retransmission and using various erasure correcting codes are compared. This modification in MAC layer will reduce the long waiting time to access the channel, as the number of users are increased.

L'utilisation intensive des services de données mobiles a de plus en plus augmenté la consommation de ressources sur les réseaux sans fil. La ressource principale utilisée pour la communication sans fil est le spectre de fréquence. À mesure que le trafic de données augmente brusquement, de nouvelles bandes du spectre de fréquences ne sont pas disponibles dans la même proportion, ce qui rend le spectre de fréquence de plus en plus rare et saturé. Plusieurs propositions ont été présentées pour optimiser l'allocation des canaux de fréquences afin d'atténuer les interférences entre les liaisons proches qui transmettent des données. Beaucoup d'entre eux utilisent un critère unique et ne considèrent pas le comportement de l'utilisateur pour guider le processus d'allocation de canaux. Les utilisateurs ont des cycles de routine et un comportement social. Ils passent au travail, à l'école, utilisent leurs appareils mobiles générant du trafic de données, et rencontrent des amis formant des groupes. Ces caractéristiques peuvent être explorées pour optimiser le processus d'allocation des canaux.Cette thèse présente une stratégie d'allocation de canaux pour les réseaux sans fil basée sur le comportement de l'utilisateur. Notre contribution principale consiste à considérer certaines caractéristiques du comportement de l'utilisateur, telles que la mobilité, le trafic et la popularité dans le processus d'allocation des canaux. De cette façon, nous priorisons l'allocation de canaux pour les nœuds qui resteront dans le réseau dans une fenêtre de temps future, avec un trafic plus élevé dans le réseau, et avec plus de popularité. Nous adoptons une approche distribuée qui permet de limiter le nombre de messages échangés dans le réseau tout en répondant rapidement aux changements de la topologie du réseau. Dans notre évaluation des performances, nous considérons des scénarios dans des réseaux ad hoc et véhiculaires, et nous utilisons des modèles de mobilité synthétique, tels que SLAW et Manhattan grid, et l'ensemble de données de traces de ville de Cologne. Dans les scénarios, nous comparons notre mécanisme avec différents types de techniques : une centralisée (nommée TABU), une autre aléatoire (nommée RANDOM), une avec la plus grande distance spectrale (appelée LD) et une avec un seul canal (appelée SC). Nous évaluons les métriques telles que le débit agrégé, le débit de livraison des paquets et le délai de bout en bout.Les simulations envisageant un scénario ad hoc avec un routage monodiffusion montrent que notre stratégie présente des améliorations en termes de débit de l'ordre de 14,81% par rapport à RANDOM et de 16,28% par rapport à l'allocation de canal LD. Dans le scénario véhiculaire, notre stratégie montre des gains de taux de livraison de paquets de l'ordre de 11,65% et de 17,18% par rapport aux méthodes RANDOM et SC, respectivement. Dans ces deux scénarios, la performance de notre stratégie est proche de la limite supérieure donnée par l'approche centralisée de TABU, mais avec l’envoie de moins des messages. / The intensive use of mobile data services has increasingly increased resource consumption over wireless networks. The main resource used for wireless communication is the frequency spectrum. As data traffic rises sharply, new bands of the frequency spectrum are not available in the same proportion, making the frequency spectrum increasingly scarce and saturated. Several proposals have been presented to optimize frequency channel allocation in order to mitigate interference between nearby links that are transmitting data. Many of them use a single criterion and does not consider the user behavior to guide the channel allocation process. Users have routine cycles and social behavior. They routinary move to work, to school, use their mobile devices generating data traffic, and they meet with friends forming clusters. These characteristics can be explored to optimize the channel allocation process.This thesis presents a channel allocation strategy for wireless networks based on user behavior. Our main contribution is to consider some characteristics of the user behavior, such as mobility, traffic, and popularity in the channel allocation process. In this way, we prioritize the channel allocation for the nodes that will remain in the network in a future time window, with higher traffic in the network, and with more popularity. We adopt a distributed approach that allows limiting the number of messages exchanged in the network while quickly responding to changes in the network topology. In our performance evaluation, we consider scenarios in ad hoc and vehicular networks, and we use some synthetic mobility models, such as SLAW and Manhattan grid, and the traces dataset of Cologne city. In the scenarios, we compare our mechanism with different types of approaches: i.e., a centralized (named TABU), a random (named RANDOM), a with largest spectral distance (named LD), and a with single channel (named SC). We evaluate metrics such as aggregated throughput, packet delivery rate, and end-to-end delay. Simulations considering ad hoc scenario with unicast routing show that our strategy presents improvements in terms of throughput at the order of 14.81% than RANDOM and 16.28% than LD channel allocation. In vehicular scenario, our strategy shows gains of packet delivery rate at the order of 11.65% and 17.18% when compared to RANDOM and SC methods, respectively. In both scenarios, the performance of our strategy is close to the upper bound search of the TABU centralized approach, but with lower overhead.

Indiana University-Purdue University Indianapolis (IUPUI) / The patients with Cystic fibrosis (CF), an inherent genetic disorder, suffer from chronic bacterial infection in the lung. In CF, modification of epithelial cells leads to alteration of the lung environment, such as inhibition of ciliary bacterial clearance and accumulation of thickened mucus in the airways. Exploiting these conditions, opportunistic pathogens like Pseudomonas aeruginosa cause lifelong persistent infection in the CF lung by forming into antibiotic-resistant aggregated communities called biofilms. Airway infections as well as inflammation are the two major presentations of CF lung disease. P. aeruginosa strains isolated from CF lungs often contain mutations in the mucA gene, and this mutation results in higher level expression of bacterial polysaccharides and toxic lipoproteins. In a previous work, we have found a putative lipoprotein gene (PA4326) which is overexpressed in antibiotic-induced biofilm formed on cultured CF-derived airway cells. In the current work, we speculated that this particular putative lipoprotein affects cellular cytotoxicity and immune-stimulation in the epithelial cells. We found that mutation of this gene (ΔPA4326) results in reduced airway cell killing without affecting other common virulence factors.Moreover, we observed that this gene was able to stimulate secretion of the proinflammatory cytokine IL-8 from host cells. Interestingly, we also found that ΔPA4326 mutant strains produced less pyocyanin exotoxin compared to the wild type. Furthermore, our results suggest that PA4326 regulates expression of the pyocyanin biosynthesis gene phzM, leading to the reduced pyocyanin phenotype. Overall, these findings implicate PA4326 as a virulence factor in Pseudomonas aeruginosa. In the future, understating the molecular interplay between the epithelial cells and putative lipoproteins like PA4326 may lead to development of novel anti-inflammatory therapies that would lessen the suffering of CF patients.

I början på år 2020 klassificerades spridningen av covid-19 som ett globalt hälsoproblem. I mars samma år fick utbrottet benämningen pandemi, vilket är den högsta nivån av en folksjukdom. Spridningen av covid-19 har inneburit stora konsekvenser som medfört omställningar för världens alla länder, företag och människor. Pandemins oförutsägbara framväxt resulterade i en ekonomisk kris, som innebär att en rubbning skett i marknadens finansiella funktion att tillgodose likviditetsbehov och omfördela risker inom ekonomin. Tidigare studier har påvisat att företag som befinner sig i ekonomiskt turbulenta perioder, likt kriser, har medfört att företagsledningar vänder sig till redovisningstekniker som medför positiva effekter i rapportsammanställningar. I vetenskapligt sammanhang benämns dessa redovisningstekniker som earnings management. Studiens syfte är att undersöka om earnings management förekommit i svenska marknadsnoterade företag åren innan utbrottet av covid-19. Dessutom ämnar studien till att kontrollera om pandemins utbrott ökat förekomsten av earnings management bland svenska börsnoterade företag.Studiens genomförande grundade sig i en kvantitativ forskningsansats där kvantifierbara data sammanställts genom företags årsredovisningar från börslistorna large cap, mid cap och small cap för urvalsperioden 2012 till 2020. Mätningen av earnings management har skett genom sammanställningar av godtyckliga periodiseringar framräknade genom den modifierade Jones-modellen. Studiens resultat visade att de analyserade företagen tillämpade earnings management under perioden innan utbrottet av pandemin. Vidare visade resultatet att tillämpningen av earnings management inte ökat signifikant efter utbrottet av pandemin, vilket gick emot författarnas antaganden baserade på tidigare forskning och studier. Resultatet visade däremot en signifikant skillnad på tillämpad earnings management med hänsyn till företagsstorlek, i enlighet med tidigare studier och redovisningsteorier. Studiens slutsats innebar att fenomenet earnings management förekommer i svenska marknadsnoterade företag. Studien har däremot inte kunnat påvisa en signifikant ökning av tillämpad earnings management efter utbrottet av pandemin. Dessutom har forskarna påvisat att mindre företag tillämpar earnings management i en större utsträckning i jämförelse med större bolag. / In early 2020, the spread of covid-19 was classified as a global health problem. In March of the same year, the outbreak was designated a pandemic, which is the highest level of a public disease. The spread of covid-19 has had a major impact that has caused upheaval for every country, business and person in the world. The unpredictable emergence of the pandemic resulted in an economic crisis, disrupting the financial function of the market to meet liquidity needs and reallocate risk within the economy. Previous studies have shown that firms in economically turbulent periods, like crises, have caused managers to turn to accounting techniques that produce positive effects in reporting summaries. In the scientific context, these accounting techniques are referred to as earnings management. The aim of this study is to investigate whether earnings management has occurred in Swedish listed companies in the years prior to the outbreak of Covid-19. In addition, the study aims to test whether the pandemic outbreak has increased the prevalence of earnings management among Swedish listed companies. The study was based on a quantitative research approach in which quantifiable data were compiled through firms annual reports from the large cap, mid cap and small cap listings for the sample period 2012 to 2020. The measurement of earnings management was done through compilations of arbitrary accruals computed by the modified Jones model. The results of the study showed that the analyzed firms applied earnings management in the period before the outbreak of the pandemic. Furthermore, the results showed that the application of earnings management did not increase significantly after the outbreak of the pandemic, which was contrary to the authors assumptions based on previous research and studies. However, the results showed a significant difference in the application of earnings management with respect to firm size, in line with previous studies and accounting theories. The study concluded that earnings management is a used phenomenon in Swedish listed companies. However, the study did not find a significant increase in the use of earnings management after the outbreak of the pandemic. In addition, the researchers have shown that smaller companies apply earnings management to a greater extent in comparison with larger companies. This master's thesis is written in Swedish.

Indiana University-Purdue University Indianapolis (IUPUI) / Candida albicans and Candida glabrata are opportunistic human pathogens that are the leading cause of fungal infections, which are increasingly becoming the leading cause of sepsis in immunosuppressed individuals. C. glabrata in particular has become a significant concern due to the increase in clinical isolates that demonstrate resistance to triazole antifungal drugs, the most prevalent treatment for such infections. Triazole drugs target the ERG11 gene product and prevent C-14 demethylation of the first sterol intermediate, lanosterol, preventing the production of the pathways end product ergosterol. Ergosterol is required by yeast for cell membrane fluidity and cell signaling. Furthermore, C. glabrata, and not C. albicans, has been reported to utilize cholesterol as a supplement for growth. Although drug resistance is known to be caused by an increase in expression of drug efflux pumps, we hypothesize a second mechanism: that the overuse of triazole drugs has lead to the increase of resistance by C. glabrata through a 2-step process: 1) the accumulation of ergosterol auxotrophic mutations and 2) mutants able to take up exogenous cholesterol anaerobically in the body acquire a second mutation allowing uptake of cholesterol aerobically. Two groups of sterol auxotrophic C. glabrata clinical isolates have been reported to take up sterol aerobically but do not produce a sterol precursor. Sterol auxotrophs have been created in C. glabrata by disrupting different essential genes (ERG1, ERG7, ERG11, ERG25, and ERG27) in the ergosterol pathway to assess which ergosterol mutants will take up sterols aerobically. Random and site-directed mutagenesis was also completed in ERG25 of Saccharmoyces cerevisiae. The ERG25 gene encodes a sterol C-4 methyloxidase essential for sterol biosynthesis in plants, animals, and yeast. This gene functions in turn with ERG26, a sterol C-3 dehydrogenase, and ERG27, a sterol C-3 keto reductase, to remove two methyl groups at the C-4 position on the sterol A ring. In S. cerevisiae, ERG25 has four putative histidine clusters, which bind non-heme iron and a C-terminal KKXX motif, which is a Golgi to ER retrieval motif. We have conducted site-directed and random mutagenesis in the S. cerevisiae wild-type strain SCY876. Site-Directed mutagenesis focused on the four histidine clusters, the KKXX C-terminal motif and other conserved amino acids among various plant, animal, and fungal species. Random mutagenesis was completed with a procedure known as gap repair and was used in an effort to find novel changes in enzyme function outside of the parameters utilized for site-directed mutagenesis. The four putative histidine clusters are expected to be essential for gene function by acting as non-heme iron binding ligands bringing in the oxygen required for the oxidation-reduction in the C-4 demethylation reaction.