As global investments in renewable energy technologies continue to grow, their effects on electricity markets are a challenge for regulators and policymakers. The thesis examines the effects of forecast errors of Czech and German renew- able energy sources on the size and volatility of the system imbalance of the Czech balancing market. Using a quantile regression and ARFIMA-GARCH models on hourly data, I found that higher solar and wind forecast errors in- crease the system imbalance in absolute terms and affect the volatility. The results show that the Czech solar and wind forecast errors have significantly higher effect than the German forecast errors on the size and volatility of the system imbalance. The strongest effect on the size and volatility of the system imbalance have the Czech solar forecast errors. Therefore, the Czech govern- ment should insist on improving the accuracy and availability of renewable energy forecasts from the transmission system operator ČEPS. Klasifikace JEL C14, C50, Q42 Klíčová slova renewable sources, forecast errors, balanc- ing market, system imbalance

Title: Effect of extended physical education in children under school age. Objective: The project aims to find out whether pupils with extended physical education will achieve better results in functional muscle tests than children with standard two-hour physical education lessons per week. Methods: This is a pilot study where the quantitative nature of the research based on a comparison of the results of six functional muscle tests on shortened muscle groups predominates. Pupils were divided into two groups according to the number of physical education hours per week. Pearson's chi-square test was used to determine the level of muscle shortening, the significance level was set at α <0.05. Results: In the individual tests of functional muscle tests, pupils with three hours of physical education per week were better in most cases. Statistical analysis of the prevalence of individual types of muscle group weakness revealed a significantly better result (p ˂ 0.05) in three functional muscle tests. Specifically in postural stereotype according to Mathias, Thomayer exam and lateral flexion exam by pupils with extended TV. Key words: Muscular imbalance, younger school age, extended physical education.

Titel: Upplevelser av aktivitetsbalans och dess påverkan på stress för studenter under pandemin covid-19. Syfte: Syftet med studien var att beskriva hur studenter på en svensk högskola upplever aktivitetsbalans och dess påverkan på stress under pandemin covid-19. Metod: En kvalitativ intervjustudie med 10 svenska informanter där materialet analyserades med en kvalitativ innehållsanalys. Resultat: I resultatet kom det fram 3 kategorier: Minskade möjligheter i att delta i aktiviteter påverkar aktivitetsbalansen, Strategier för att upprätthålla aktivitetsbalans och Relationen mellan aktivitetsbalans och stress. Resultatet visade upplevelserna av aktivitetsbalans och dess påverkan på stress hos informanterna. Slutsats: Fungerande rutiner och anpassade aktiviteter var av betydelse för upplevd aktivitetsbalans under pandemin covid-19. Upplevelsen av att pandemin påverkat aktivitetsbalans negativt var på grund av bristande rutiner och anpassningar i vardagen. Vid upplevd aktivitetsobalans sågs en verkan på stress men med tidigare erfarenhet av stresshantering kunde det undvikas. / Title: The experiences of occupational balance and its impact on stress for students during the covid-19 pandemic. Aim: The purpose of the study was to describe how students at a Swedish university experience occupational balance and its impact on stress during the pandemic covid-19. Method: A qualitative interview study was used with 10 Swedish participants and the material was analyzed with a qualitative content analysis. Result: The result revealed 3 categories: Reduced opportunities in participating in activities affect the occupational balance, Strategies for maintaining occupational balance and The relationship between occupational balance and stress. The results showed experiences of occupational balance and its impact on between informants Conclusion: Functioning routines and adapted activities were important for the perceived occupational balance during the covid-19 pandemic. The experience that the pandemic had a negative effect on the balance of activities was due to a lack of routines and adaptations in everyday life. In the case of perceived occupational imbalance, an effect on stress was seen, but with previous experience of stress management, it could be avoided.

The brain network is a multiscale hierarchical organization from neurons and local circuits to macroscopic brain areas. The precise synaptic transmission at each synapse is therefore crucial for neural communication and the generation of orchestrated behaviors. Activation of presynaptic voltage-gated calcium channels (CaV2) initiates synaptic vesicle release and plays a key role in neurotransmission. In this dissertation, I have aimed to uncover how CaV2 activity affects synaptic transmission, circuit function and behavioral outcomes using Caenorhabditis elegans as a model. The C. elegans genome encodes an ensemble of highly conserved neurotransmission machinery, providing an opportunity to study the molecular mechanisms of synaptic function in a powerful genetic system. I identified a novel gain of function CaV2α1 mutation that causes CaV2 channels to activate at a lower membrane potential and slow the inactivation. Cell-specific expression of these gain-of-function CaV2 channels is sufficient to hyper-activate neurons of interest, offering a way to study their roles in a given circuit. CaV2(gf) mutants display behavioral hyperactivity and an excitation-dominant synaptic transmission. Imbalanced excitation and inhibition of the nervous system have been associated with several neurological disorders, including Familial Hemiplegic Migraine type 1 (FHM1) which is caused by gain- of-function mutations in the human CaV2.1α1 gene. I showed that animals carrying C. elegans CaV2α1 transgenes with corresponding human FHM1 mutations recapitulate the hyperactive behavioral phenotype exhibited by CaV2(gf) mutants, strongly suggesting the molecular function of CaV2 channels is highly conserved from C. elegans to human. Through performing a genome-wide forward genetic screen looking for CaV2α(gf) suppressors, we isolated new alleles of genes that required for CaV2 trafficking, localization and function. These regulators include subunits of CaV2 channel complex, components of synaptic and dense core vesicle release machinery as well as predicted extracellular proteins. Taken together, this work advances the understanding of CaV2 malfunction at both cellular and circuit levels, and provides a genetically amenable model for neurological disorders associated with excitation-inhibition imbalance. Additionally, through identifying regulators of CaV2, this research provides new avenues for understanding the CaV2 channel mediated neurotransmission and potential pharmacological targets for the treatments of calcium channelopathies.

Data imbalance has been a challenge in many areas of automatic classification. Many popular approaches including over-sampling, under-sampling, and Synthetic Minority Oversampling Technique (SMOTE) have been developed and tested in previous research. A big problem with these techniques is that they try to solve the problem by modifying the original data rather than truly overcome the imbalance and let the classifiers learn. For tasks in areas like remote sensing and depression detection, the imbalanced data challenge also exists. Researchers have made efforts to overcome the challenge by adopting methods at the data pre-processing step. However, in remote sensing and depression detection tasks, the main interest is still on applying different new classifiers such as deep learning which has powerful classification ability but still do not consider data imbalance as prime factor of lower classification performance. In this thesis, we demonstrate the performance of K-CR in our evaluation experiments on a urban land cover classification dataset and on two depression detection datasets. The latter two datasets consist in social media texts (tweets), therefore we propose to adopt a feature selection technique Term Frequency - Category-Based Term Weights (TF-CBTW) and various word embedding techniques (Word2Vec, FastText, GloVe, and language model BERT). This feature selection method was not applied before in similar settings and we show that it helps to improve the efficiency and the results of the K-CR classifier. Our three experiments show that K-CR can achieve comparable performance on the majority classes and better performance on minority classes when compared to other classifiers such as Random Forest, K-Nearest Neighbour, Support Vector Machines, Multi-layer Perception, Convolutional Neural Networks, and Long Short-Term Memory.

Le contrôle de l’équilibre contractuel constitue l’un des marqueurs du droit des contrats contemporain. Plusieurs fondements président à l’instauration d’un tel contrôle. Certains auteurs évoquent la morale, d’autres la justice contractuelle et d’autres enfin son utilité économique. Appliqués aux déséquilibres entre professionnels, les outils mis en œuvre pour assurer ce contrôle trahissent l’existence d’un contrôle objectif de l’équilibre attendu du contrat. L’équilibre subjectif voulu par les parties n’est pas écarté, mais il se trouve concurrencé par la détermination d’une forme d’équilibre objectif motivé tant par la volonté de protéger la partie faible que par celle de promouvoir une certaine vision de l’économie, et des échanges commerciaux. Le droit des pratiques restrictives se présente à cet égard comme une discipline intégratrice permettant d’allier protection de la partie faible et protection du marché. L’influence que cette discipline exerce sur le droit commun des contrats, et la « civilisation », à l’inverse, du droit de la concurrence sous l’influence du droit commun, permettent d’éclairer les rouages de ce contrôle objectif de l’équilibre contractuel. Cette étude propose de décrire l’objectivation des critères d’identification du déséquilibre contractuel et celle des remèdes qui lui sont réservés. Pour ce faire, le droit commun des contrats et celui des pratiques restrictives de concurrence seront mis en miroir afin d’éclairer les implications de ce contrôle sur l’une et l’autre des matières. Plus exactement, cette thèse propose de déjouer les phénomènes de superposition et de concurrence des dispositifs de contrôle objectif de l’équilibre contractuel existant dans ces deux disciplines par une identification précise de leurs champs d’applications et de leurs objectifs respectifs. Elle tend enfin à décrire les fonctions de ce contrôle objectif tant à l’égard des parties qu’à celui du marché, en insistant sur la nécessité d’envisager conjointement les dimensions micro et macro-économiques des contrats étudiés. / Control of contractual balance is one of the markers of contemporary contract law. Such control is grounded in several basic concepts: some authors refer to morality, while others invoke contractual justice or its economic relevance. Applied to imbalance between professionals, the tools implemented to ensure this control reveal the existence of objective control of the contracts’ expected balance. Although the subjective balance sought by the parties is not set aside, it is overshadowed by the determination of a kind of objective balance motivated by a will both to protect the weaker party and to promote a certain vision of the economy, and commercial exchanges. In this respect, restrictive practices law is an integrative discipline in which it is possible to combine protection of the weaker party with protection of the market. The influence of this discipline on common contract law and, conversely, the “civilization” of competition law under the influence of common law help better understand the mechanism of such objective control of contractual balance. This research aims to describe the objectification of identification criteria for contractual imbalance and the ways of remedying it. To this end, common contract law and law governing restrictive competition practices will be compared to shed light on such control in both these areas. More specifically, this thesis proposes to thwart phenomena of superimposition of and competition between existing systems for the objective control of contractual balance in both these disciplines through precise identification of their fields of application and their respective purposes. It also aspires to describe the functions of such objective control for both the parties and the market by emphasizing the need to examine these contracts by taking into consideration together both their micro and macroeconomic dimensions.

T-2 toxin (T-2), produced by the genus Fusarium, is a cytotoxic trichothecene mycotoxin, a feed contaminant, and has been shown to be immunomodulatory. It is suspected that T-2-associated immunomodulation is mediated partly through the hypothalamic-pituitary-adrenal axis. The presence of endotoxin, a bacterial product capable of activating the hypothalamic-pituitary-adrenal axis as well as the levels of several hormones, also associated with activation of the hypothalamic-pituitary-adrenal axis, were determined in both vehicle- and toxin-treated animals. Endotoxemia was evident twenty-four hours after a single oral exposure to T-2. Blood levels of adrenocorticotropic hormone and corticosterone, parameters of the stress response, also increased twenty-four hours after T-2 exposure. Hypothalamic norepinephrine and serum corticosterone levels increased in a dose-related manner after two weeks of T-2 exposure. An increased corticosteroid level was associated with thymic involution leading potentially to decreased T-dependent antibody response, a known effect of T-2. The effects of exposure to T-2 on the development of both T-dependent and T-independent antibody response were determined in nonoperated, sham-operated and adrenalectomized mice. T-2 decreased the antibody response to a T-dependent antigen and increased a T-independent response. The effects of T-2 were partially nullified by adrenalectomy. These results provide a further confirmation of the postulate that the hypothalamic-pituitary-adrenal axis plays an important role in T-2 toxin-immunomodulation. In vitro studies were undertaken to investigate the direct effects of T-2 on various populations of lymphatic cells. Exposure to T-2 after twenty-four hours caused an increase in the uptake of 3H-thymidine by mouse splenic cells. Pokeweed mitogen stimulation also increased in this system; the response to lipopolysaccharide increased to a lesser extent. However, T-cell responses to phytohaemagglutinin and concanavalin A (Con A) decreased. Thymic cells were also sensitive to T-2. The possibility of pharmacological activity of T-2 with thymocytes was investigated. Both specific and nonspecific cell associations were observed. The association of T-2 with thymocytes was altered in the presence of dexamethasone, a synthetic corticosteroid. T-2 was shown to have both indirect as well as direct activities on the immune system. Endocrine dysfunction resulting from chronic stress and possible pharmacologic activity of T-2 provide the impetus for further investigations.

No description available.

In this study, we systematically investigate the impact of class imbalance on classification performance of convolutional neural networks and compare frequently used methods to address the issue. Class imbalance refers to significantly different number of examples among classes in a training set. It is a common problem that has been comprehensively studied in classical machine learning, yet very limited systematic research is available in the context of deep learning. We define and parameterize two representative types of imbalance, i.e. step and linear. Using three benchmark datasets of increasing complexity, MNIST, CIFAR-10 and ImageNet, we investigate the effects of imbalance on classification and perform an extensive comparison of several methods to address the issue: oversampling, undersampling, two-phase training, and thresholding that compensates for prior class probabilities. Our main evaluation metric is area under the receiver operating characteristic curve (ROC AUC) adjusted to multi-class tasks since overall accuracy metric is associated with notable difficulties in the context of imbalanced data. Based on results from our experiments we conclude that (i) the effect of class imbalance on classification performance is detrimental and increases with the extent of imbalance and the scale of a task; (ii) the method of addressing class imbalance that emerged as dominant in almost all analyzed scenarios was oversampling; (iii) oversampling should be applied to the level that totally eliminates the imbalance, whereas undersampling can perform better when the imbalance is only removed to some extent; (iv) thresholding should be applied to compensate for prior class probabilities when overall number of properly classified cases is of interest; (v) as opposed to some classical machine learning models, oversampling does not necessarily cause overfitting of convolutional neural networks. / I den här studien undersöker vi systematiskt effekten av klassobalans på prestandan för klassificering hos konvolutionsnätverk och jämför vanliga metoder för att åtgärda problemet. Klassobalans avser betydlig ojämvikt hos antalet exempel per klass i ett träningsset. Det är ett vanligt problem som har studerats utförligt inom maskininlärning, men tillgången av systematisk forskning inom djupinlärning är starkt begränsad. Vi definerar och parametriserar två representiva typer av obalans, steg och linjär. Med hjälpav tre dataset med ökande komplexitet, MNIST, CTFAR-10 och ImageNet, undersöker vi effekterna av obalans på klassificering och utför en omfattande jämförelse av flera metoder för att åtgärda problemen: översampling, undersampling, tvåfasträning och avgränsning för tidigare klass-sannolikheter. Vår huvudsakliga utvärderingsmetod är arean under mottagarens karaktäristiska kurva (ROC AUC) justerat för multi-klass-syften, eftersom den övergripande noggrannheten är förenad med anmärkningsvärda svårigheter i samband med obalanserade data. Baserat på experimentens resultat drar vi slutsatserna att (i) effekten av klassens obalans påklassificeringprestanda är skadlig och ökar med mängden obalans och omfattningen av uppgiften; (ii) metoden att ta itu med klassobalans som framträdde som dominant i nästan samtliga analyserade scenarier var översampling; (iii) översampling bör tillämpas till den nivå som helt eliminerar obalansen, medan undersampling kan prestera bättre när obalansen bara avlägsnas i en viss utsträckning; (iv) avgränsning bör tillämpas för att kompensera för tidigare sannolikheter när det totala antalet korrekt klassificerade fall är av intresse; (v) i motsats till hos vissa klassiska maskininlärningsmodeller orsakar översampling inte nödvändigtvis överanpassning av konvolutionsnätverk.

The current study focuses on improving and testing the CTF thermalhydraulics computer code. CTF is a thermalhydraulic code used for subchannel analysis of nuclear power reactors developed as part of the US DOE CASL program and distributed by North Carolina State University. Subchannel analyses are used to predict the local fuel temperatures and coolant conditions inside a complex nuclear fuel assembly. Such calculations are used to improve designs of nuclear fuel, improve operating margins, or perform safety analysis. An important part of the code development process is the verification and validation for its intended use. In this work validation activities are performed using the RISO experiments are modeled in CTF for adiabatic and diabatic cases in annular flow regimes and a limited set of tests in CANDU geometries. The CTF predictions significantly overpredicted the pressure drop for cases involving annular flow conditions. Depending on the application, such overprediction can result in significant errors in the computation of fuel element dryout and other figures of merit. For example, an analysis using fixed pressure boundary conditions CTF predicts much lower subchannel flows and hence fuel element temperatures may be overestimated. On the other hand, for a scenario with mass flux and inlet pressure as boundary conditions, the impact of pressure drop discrepancies on dryout predictions may be lower. Therefore, there is a particular focus in this thesis on the two-phase pressure drop models and the RISO experiment specifically, since the RISO tests involve a range of annular flow conditions which is prototypical of many CANDU accident analysis conditions. In addition to the RISO experiments, 28-element CANDU full scale rod bundle experiments are modeled in CTF for single-phase and two-phase flow conditions. Cases are modeled for crept and uncrept conditions with different bearing pad heights i.e., 1.17 mm and 1.35mm. Pressure drop predictions are compared with the experimental results where single-phase comparisons are in good agreement while an overprediction of ~25% is observed for two-phase conditions. The effect of bearing pads on the subchannel local parameters, like mass flow rate, are also studied. Furthermore, the effect of turbulent mixing rate on subchannel enthalpy distribution in the bundle and CHF in different subchannels is also analyzed. Based on the comparison to the RISO and CANDU 28 element test databases, the overprediction of pressure drop in the annular flow regime needs improvement in the current version of CTF. This overprediction of the frictional pressure drop results from either wall drag or interfacial shear stress phenomena. In this study, it is demonstrated that the issue occurs mostly as a result of interfacial friction factor modelling this work examines several alternative approaches. The results show the Ju’s and Sun’s interfacial friction factor better predicts the results among all the other six correlations implemented in CTF. The major impediment in further testing of CTF is that it lacks the capability to simulate R-134a fluids. Given there is a large database of R-134a two-phase tests, another aspect of this thesis is to extend CTF for application and validation using refrigerants. The current CTF version only supports fluid properties for water and FLiBe salts. By adding R-134a fluid properties the testing and validation range of CTF is broadened for different experiments performed using R-134a fluids. CHF experiments are modeled in CTF and results are compared with experimental data. For local conditions correlation, 2006 water LUT are used to predict CHF and DNBR. The fluid-to-fluid scaling method is applied in CTF when using CTF with R-134a fluid properties for CHF and DNBR predictions to account for the difference in fluid properties between R-134a and the CHF look-up table. / Thesis / Master of Applied Science (MASc) / COBRA-TF (CTF) is a thermalhydraulic code, based on the historical code COBRA-TF, used for subchannel analysis of nuclear power reactors. Subchannel analysis can be used to predict the local fuel temperatures and coolant conditions inside a complex nuclear fuel assembly. CTF is a transient code that simultaneously solves conservation equations for mass, momentum, and energy for the three coolant phases present, i.e. vapor, continuous liquid, and entrained liquid droplet phases. The scope of the current study includes 1) testing the code for conditions relevant to CANDU accident analysis, 2) refinement of the models that are used in two-phase interfacial friction calculations, and 3) inclusion of alternate fluid properties. The testing of CTF is performed with different experimental databases covering CANDU thermalhydraulic conditions. The refinement is done by improving the pressure drop prediction in the annular flow regime by using different interfacial friction factor correlations from earlier studies in the literature. The current CTF version includes water and liquid salt properties (FLiBe) for coolant fluids. Freon (R-134a) fluid properties have been added in CTF in order to broaden the testing range of CTF for different experimental database using R-134a as working fluid.