DEAD-BOX (DDX) RNA helicases are a large family of proteins characterized by the presence of a DEAD/H (Asp-Glu-Ala-Asp/His) motif. Their main function is to unwind double stranded RNA to promote downstream molecular events. They are involved in virtually all steps of RNA metabolism such as transcription, translation, RNA export and degradation, ribosome biogenesis and pre-mRNA splicing. The aim of my work was to investigate the functions of human DDX3X and DDX54 RNA helicases, particularly in in vitro cancer models. To provide insight into their molecular functions, I identified RNAs bound by DDX3X and DDX54 in breast cancer (MCF7) cells by performing iCLIP experiments. This generated two very distinct RNA binding profiles: DDX3X preferentially bound exonic regions of mRNAs encoding translational factors, whilst DDX54 preferentially bound non-coding RNAs and intronic regions of mRNAs encoding nuclear proteins. Further bioinformatic analysis identified a few discrete binding motifs within DDX3X target RNAs. One of these, within the human JUND transcript, was validated as a DDX3X binding site using electrophoretic mobility shift assays. Notably, the levels of proteins encoded by mRNAs bound by DDX3X were altered following knockdown of the helicase. These data highlight the importance of DDX3X in maintaining appropriate levels of certain proteins, which in turn may explain at least some of the changes in phenotype observed upon DDX3X knockdown. In this regard, I showed that knocking down DDX3X or DDX54 in MCF7 cells slowed cell proliferation by inducing a G1/S phase arrest. Furthermore, a CRISPR/Cas9 dropout screen in a leukaemia cell line (MLL-AF9) showed that both helicases are essential for growth of these cells. However, loss of DDX3X or DDX54 had little effect on proliferation of immortalized NIH3T3 cells indicating that their loss is not generally lethal. In subsequent CRISPR/Cas9 dropout screens in various other cancer cell lines, including some derived from solid tumours, DDX54 was found to be essential for growth of all cell lines. In contrast, DDX3X was required for proliferation of only a subset of these. Focusing on DDX3X, I identified that the integrity of the helicase's RNA binding domains is essential for growth and cell cycle progression of an acute myeloid leukaemia cell line (OCI-AML3). Overall, my findings shed mechanistic insight upon the role of DDX RNA helicases in cancer and identify DDX3X and DDX54 as potential targets for therapeutic intervention in certain cancers.

<p>Syftet med högskoleavhandlingen var att konstruera en klass-D förstärkare för audio med en DDXi-2161 krets från Apogee. Förstärkaren har en digital stereoingång för I²S-format. Digitalisering av en analog audiosignal sker med codec-kretsen WM8731 från Wolfson. För att möjliggöra implementering av funktioner för digital signalbehandling av audiosignalen ingår en FPGA-krets från Altera i systemet. Gränssnitten mellan codec-kretsen och FPGA:n samt FPGA:n och klass-D förstärkaren är beskrivna med VHDL och implementerade i FPGA:n. Klass-D förstärkaren har byggts upp på ett två-lagers mönsterkort. Ett utvecklingskort från ALTERA (DE2) med codec-krets och FPGA har använts. Resultaten visar goda möjligheter att konstruera en klass-D förstärkare med bra ljud och låg effektförbrukning.</p>

Syftet med högskoleavhandlingen var att konstruera en klass-D förstärkare för audio med en DDXi-2161 krets från Apogee. Förstärkaren har en digital stereoingång för I²S-format. Digitalisering av en analog audiosignal sker med codec-kretsen WM8731 från Wolfson. För att möjliggöra implementering av funktioner för digital signalbehandling av audiosignalen ingår en FPGA-krets från Altera i systemet. Gränssnitten mellan codec-kretsen och FPGA:n samt FPGA:n och klass-D förstärkaren är beskrivna med VHDL och implementerade i FPGA:n. Klass-D förstärkaren har byggts upp på ett två-lagers mönsterkort. Ett utvecklingskort från ALTERA (DE2) med codec-krets och FPGA har använts. Resultaten visar goda möjligheter att konstruera en klass-D förstärkare med bra ljud och låg effektförbrukning.

The main subject of this diploma’s thesis is the creation of laboratory task on the partial discharge. The thesis is made up of two parts: theoretical and practical. In the theoretical part there are information about partial discharge. One of them is classification partial discharge by type, effects of partial discharge in insulation systems, parameters to assess the quality of electrical insulation of power systems and measurement techniques. Further part is user’s manual for measurement instrument. In practical part is created laboratory task on problematic of the partial discharge measurement. It is demonstrative measure of partial discharge with the aim of understanding problematic of partial discharge, calibration and noise.

This diploma thesis deals with digital audio amplifier with universal inputs and its design. The first part describes modulation and audio formats for audio electronics. The thesis contain design of a block diagram of the digital audio amplifier and describes the requirements for functional blocks. As a basic device for audio signal processing was choosen integrated circuit STA326. The thesis continue with circuits design for each blocks with a description of their principles. The next section describes the construction and firmware for microcontroller. The last part of this diploma thesis is targeted on the presentation of the measured parameters of the amplifier. The conclusion summarizes the results that have been achieved and advantages and disadvantages of the digital audio amplifier prototype.

The main topic of this work is the analysis of the measurement of partial discharge measurements on high voltage cables. The thesis also deals with other measurements, including the measurement of the loss factor and the voltage retention and breakdown test. Part of the text describes the issue of partial discharge, its measurement by galvanic method and methods of elimination of disturbing influences that affect this method in terms of sensitivity and accuracy of the measured values. Thesis also describes the construction of the cables, their marking and the tests carried out on them. There is also a description of the cable terminals used for measuring, especially water terminals, which are designed for high voltages and which are carried out in the practical part of the thesis. The next part deals with problems prior to the commissioning of water terminals and their preparation for certain tests, including description and evaluation of the results of the measurements.

The main subject of the final thesis is to find a suitable method for measuring the partial discharge (PD) in the dielectric of high-voltage capacitor. In the theoretical part of my thesis contains from the mechanisms of origin and the harmful effects of partial discharge at high voltage insulation of capacitor. It describes the global galvanic method of partial discharge measurement, the principle of cascade voltage multiplier, its main components are high-voltage capacitor and diode, facilities quality measurement of capacitors for voltage multipliers, advantages and disadvantages and principles of HIPOTRONICS DDX-8003 with the pulse discrimination system. In the experimental part of the diploma thesis is familiar with the diagnostics of high – voltage capacitors by means of laboratory measurements on the electronic bridge and with the help of partial discharge measurement system. Design of suitable electrode arrangement is described which eliminates the influence of corona which makes it impossible to measure partial discharges and the dissipation factor (tg ). Analysis data from measurement and determination of quality level, eventual degradation of measured capacitors. The result of this project should be designed the methodology for finding of poor – quality capacitors in order to increase the reliability of the voltage multiplier.

The main subject of the final thesis is to find a suitable method for measuring the partial discharge (PD) in the dielectric of high-voltage capacitor. In the theoretical part of thesis contains from the mechanisms of origin and the harmful effects of partial discharge at high voltage insulation of capacitor. It describes the global galvanic method of partial discharge measurement, the principle of cascade voltage multiplier, its main components (high-voltage capacitor and diode). Nowadays are presented the possibilities of measuring the quality of capacitors for voltage multipliers. In the experimental part of the diploma thesis is familiar with the diagnostics of high – voltage capacitors by means of laboratory measurements on the electronic bridge and with the help of partial discharge measurement system. It describes the design of a suitable electrode arrangement that eliminates the influence of the corona, which makes it impossible to measure partial discharges and the dissipation factor tg . The thesis analyzes the obtained data from measurements and determines the quality level or the degradation of the measured capacitors. The result of the project should be designed the methodology for finding poor quality capacitors in order to increase the reliability of the voltage multiplier.