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Design and realization of USB sound card with a guitar and microphone preamplifier
Bajzík, Jakub ; Hanák, Pavel (referee) ; Krajsa, Ondřej (advisor)
The term paper analyzes the available audio codecs platforms for the implementation of an external sound card with USB interface. It includes a complete design of differential microphone preamplifier with balanced input and single-ended guitar preamplifier with unbalanced input. The main circuit is completed by dual supply voltage, phantom power and signal indication. The term paper also includes a software simulation of preamplifier circuits and design of the printed circuit board. The final product was measured focusing on audio signal transfer.
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The influence of stochastic behaviour of ion channels on the signal and information transfer at excitable neuronal membranes
Šejnová, Gabriela ; Kuriščák, Eduard (advisor) ; Maršálek, Petr (referee)
The stochastic behavior of voltage-gated ion channels causes fluctuations of conductances and voltages across neuronal membranes, contributing to the neuronal noise which is ubiquitous in the nervous system. While this phenomenon can be observed also on other parts of the neuron, here we concentrated on the axon and the way the channel noise influences axonal input-output characteristics. This was analysed by working with our newly created computational compartmental model, programmed in Matlab environment, built up using the Hodgkin-Huxley mathematical formalism and channel noise implemented via extended Markov Chain Monte Carlo method. The model was thoroughly verified to simulate plausibly a mammalian axon of CA3 neuron. Based on our simulations, we confirmed quantitatively the findings that the channel noise is the most prominent on membranes with smaller number of Na+ and K+ channels and that it majorly increases the variability of travel times of action potentials (APs) along axons, decreasing thereby the temporal precision of APs. The simulations analysing the effect of axonal demyelination and axonal diameter correlated well with other finding referred in Literature. We further focused on spike pattern and how is its propagation influenced by inter-spike intervals (ISI). We found, that APs fired...
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Design and realization of USB sound card with a guitar and microphone preamplifier
Bajzík, Jakub ; Hanák, Pavel (referee) ; Krajsa, Ondřej (advisor)
The term paper analyzes the available audio codecs platforms for the implementation of an external sound card with USB interface. It includes a complete design of differential microphone preamplifier with balanced input and single-ended guitar preamplifier with unbalanced input. The main circuit is completed by dual supply voltage, phantom power and signal indication. The term paper also includes a software simulation of preamplifier circuits and design of the printed circuit board. The final product was measured focusing on audio signal transfer.
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Interdoménové a intradoménové interakce u motorové podjednotky EcoR124I: Výpočetní studie
SINHA, Dhiraj
EcoR124I is a Type I restrictionmodification (RM) enzyme and as such forms multifunctional pentameric complexes with DNA cleavage and ATP-dependent DNA translocation activities located on the motor subunit HsdR. When non-methylated invading DNA is recognized by the complex, two HsdR endonuclease/motor subunits start to translocate dsDNA without strand separation activity up to thousands base pairs towards the stationary enzyme while consuming ~1 molecule of ATP per base pair advanced. Whenever translocation is stalled the HsdR subunits cleave the dsDNA nonspecifically far from recognition site. The X-ray crystal structure of HsdR of EcoR124I bound to ATP gave a first insight of structural/functional correlation in the HsdR subunit. The four domains within the subunit were found to be in a square planer arrangement. Computational modeling including molecular dynamics in combination with crystallography, point mutations, in vivo and in vitro assays reveals how interactions between these four domains contribute to ATP-dependent DNA translocation, DNA cleavage or inter-domain communication between the translocase and endonuclease activities.
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