Mobile Application for DNS Administration

Táto bakalárska práca sa zaoberá možnosťami a špecifikami tvorby vlastnej mobilnej aplikácie pre správu DNS na systém Android. Cieľom je vytvorenie prehľadnej aplikácie, jednoduchej na ovládanie, ktorá používateľovi umožní manažovať zóny a záznamy DNS doménového serveru BIND9. Tento problém rieši manipuláciou zónových súborov cez SSH pripojenie, ktorá je ovládaná moderným používateľským rozhraním. Výsledný program umožňuje používateľom pohodlne spravovať DNS server zo svojho chytrého telefónu prakticky hocikde.This bachelor's thesis deals with possibilities and specifics of developing a custom mobile applicaion for DNS administration on Android. The goal is to create an easy-to-use application which will allow the user to manage zones and resource records of BIND9 nameserver. This issue is solved by manipulation of zone files over SSH connection, controlled through the modern user interface. The resulting programm allows the users to comfortably manage a DNS server from their smartphone practically anywhere.

Hydrodynamic Trapping of Swimming Bacteria by Convex Walls

Swimming bacteria display a remarkable tendency to move along flat surfaces for prolonged times. This behavior may have a biological importance but can also be exploited by using microfabricated structures to manipulate bacteria. The main physical mechanism behind the surface entrapment of swimming bacteria is, however, still an open question. By studying the swimming motion of Escherichia coli cells near microfabricated pillars of variable size, we show that cell entrapment is also present for convex walls of sufficiently low curvature. Entrapment is, however, markedly reduced below a characteristic radius. Using a simple hydrodynamic model, we predict that trapped cells swim at a finite angle with the wall and a precise relation exists between the swimming angle at a flat wall and the critical radius of curvature for entrapment. Both predictions are quantitatively verified by experimental data. Our results demonstrate that the main mechanism for wall entrapment is hydrodynamic in nature and show the possibility of inhibiting cell adhesion, and thus biofilm formation, using convex features of appropriate curvature

Chua's Circuit in Spread Spectrum Communication Systems

Communication system via chaotic modulations is demonstrated. It contains the well-known chaotic circuits as its basic elements - Chua's circuits. The proposed system has some standard properties of spread spectrum communication. The following advantage is found in simulations: a) Transmitted signals have broad spectra. b) Secure communications are possible in the sense that the better parameter matching is required in order to recover the signal. c) The circuit structure of the communication system is most simple and communication systems are easily built at a small outlay. Finally computer simulations are given to examine the validity of this system

A Robust Chaos-Based True Random Number Generator Embedded in Reconfigurable Switched-Capacitor Hardware

This paper presents a new chaos-based True Random Number Generator (TRNG) with a decreased voltage supply sensitivity. Contrary to the traditionally used sources of randomness it uses a well-defined deterministic switched-capacitor circuit that exhibits chaos. The whole design is embedded into a commercially available mixed-signal Cypress PSoC reconfigurable device without any external components. The proposed design is optimized for a reduction of influence of the supply voltage to the quality of the generated random bit stream. The influence of circuit non-idealities is significantly reduced by the proposed XOR corrector and optimized circuit topology. The ultimate output bit rate of the proposed TRNG is 60 kbit/s and the quality of generated bit-streams is confirmed by passing standard FIPS and correlation statistical tests performed in the full range of PSoC device supply voltages

A hem érfal komponensekre kifejtett közvetlen és közvetett patofiziológiai hatásai = Pathologic effects of heme on components of vessel wall via direct and indirect mechanisms

Kimutattuk, hogy az atheroma lipid magja prooxidáns környezetet teremt, ahol a vörösvértestek szétesnek, a hemoglobin ferri- és ferrylhemoglobinná oxidálódik, és a felszabaduló hem és vas lipidoxidációt indít el. Leírtuk, hogy a hemoglobin oxidáció (ferrylhemoglobin keletkezése) a vascularis endothelium aktiválása révén kifejezett proinflammatorikus hatással rendelkezik. Demonstráltuk, hogy a hemoxigenáz-1 (Hmox1 gén) megelőzi a malária központi idegrendszeri szövődményeit kísérleti állatmodellben. A jótékony hatásokat a szénmonoxid hemoglobinhoz történő kötődése okozta, megakadályozva a hemoglobin oxidációt és a hem disszociációját, ami az idegrendszeri szövődmények kialakulásáért felelős. Kutatásaink felvetik annak a lehetőségét, hogy a nemespenésszel érlelt élelmiszerek, nevezetesen a sajttermékek, és a sziderofórokat tartalmazó funkcionális élelmiszerek beiktatása a diétában csökkentik a szív és érrendszeri megbetegedések előfordulását. Felfetük, hogy a hemoxigenáz-1/ferritin rendszer aktivitása hatékonyan gátolja a kalcifikációt és a simaizomsejtek csontsejt irányú transzformációját, és a hatást elsősorban a ferritin nehéz láncának ferroxidáz aktivitása közvetíti, másodsorban a biliverdinnek köszönhető. Továbbá, eredményeik bizonyítékot szolgáltat arra vonatkozóan, hogy a hem-stressz gátolja a csont mineralizációt, és ez a hemoxigenáz-1/ferritin aktivációnak köszönhető, közelebbről a forroxidáz aktivitásnak. | We demonstrated that interior of advanced atheromatous lesions is a pro-oxidant environment in which erythrocytes are lysed, hemoglobin is readily oxidized to ferri- and ferrylhemoglobin, and released heme and iron promote further oxidation of lipids. We revealed that oxidized hemoglobin, i.e. ferrylhemoglobin, acts as a proinflammatory agonist that targets vascular endothelial cells. We reported that heme oxygenase-1 (encoded by Hmox1) prevents the development of experimental cerebral malaria. These effects were mediated by the binding of carbon monoxide to hemoglobin, preventing hemoglobin oxidation and the generation of free heme, a molecule that triggers cerebral malaria pathogenesis. The consumption of mold-ripened food products such as aged cheeses and the introduction of functional foods and food additives rich in fungal iron chelators in diets may lower the risk of cardiovascular diseases. We conclude that induction of the heme oxygenase-1/ferritin system in response to heme prevents phosphate -mediated calcification and osteoblastic differentiation of human smooth muscle cells mainly via the ferroxidase activity of ferritin. Our studies provided evidence that heme decreases mineralization and demonstrates that this suppression is provided by heme-induced upregulation of ferritin. In addition, we conclude that inhibition of osteoblast activity, mineralization, and specific gene expression is attributed to the ferroxidase activity of ferritin

Selfish and Altruistic Bacterial Populations Maximize Fitness Under Stress by Local Segregation

Landscapes in ecology have a profound influence on the adaption and evolution of competing populations for resources. We are interested in how altruistic populations survive in the presence of selfish individuals in a non-stirred, closed and complex nutrient landscape. Well-stirred (landscape-free) but closed environments have a depressing future when selfish individuals arise in a population, a fate known as the tragedy of the Commons. Over-exploitation of a well-stirred communal habitat by selfish individuals which do not follow rules of communal self-regulation ends up in the elimination (extinction) of both the original altruistic inhabitants and the selfish population. In the context of bacterial population, the Commons tragedy that occurs is the consumption of limited resources by the individuals, resulting in metabolic stressing of the bacteria and growth advantages to be gained by defection from a ``social contract" of altruistic cooperation. There is no avoidance of this tragedy and the collapse of an original altruistic wild-type population by an emergent selfish population in a well-stirred but closed environment is inevitable. However, there is a fundamental difference between resource exploitation in a well-stirred homogenous commons and in a heterogenous landscape of nutrients which is not stirred. We show here using a non-stirred nanofabricated habitat landscape that altruists and selfish bacteria can in fact coexist, that they can maintain phenotype diversity and avoid the tragedy of the Commons. This emergent spatial segregation of competing populations under stress greatly changes, we believe, our perception of the true sophistication of bacterial response to stress and competition, and has broad implications for the adaptive strategies of higher organisms under stress in complex environments

Wideband Amplifier Final Stage 5kHz - 1,5 GHz

Tato práce se zaměřuje na problematiku návrhu koncové části širokopásmového zesilovače, který má sloužit jako náhrada za již nevyhovující zesilovač pracující v pásmu 5 KHz – 1,5 GHz. V úvodní části je vysvětlena potřebná teorie pro pochopení řešeného problému. Druhá část je věnována programování skript pro automatické měření parametrů zesilovače pomocí SCPI příkazů. Třetí část pak popisuje výběr nového aktivního prvku na základě parametrů původního zesilovače.This work is focused on the problem of design of the wideband amplifier final stage, which is designed as a replacement for the old insufficient amplifier, which works in the frequency band from 5 KHz to 1.5 GHz. First part of the work is dedicated to theoretical introduction of the problem. Second part of the work describes the created matlab scripts for automatic measurement of the amplifiers parameters via SCPI commands. The third part describes choice of the new active element based on the measured parameters of the original amplifier.

Effects of Spreading Sequences on the Performance of MC-CDMA System with Nonlinear Models of HPA

Performance evaluation and comparison of multi-carrier code division multiple access (MC-CDMA) system model for different spreading sequences at the presence of Saleh and Rapp model of high power amplifier (HPA) is investigated. Nonlinear amplification introduces degradation of bit error performance and destroys the orthogonality among subcarriers. In order to avoid performance degradation without requiring extremely large backoffs in the transmitter amplifier, it becomes convenient to use nonlinear multi-user detection techniques at the receiver side. In order to illustrate this fact, microstatistic multi-user receiver (MSF-MUD) and conventional minimum mean square error receiver (MMSE-MUD) are considered and mutually compared. The results of our analyses based on computer simulations will show very clearly, that the application of nonlinear MSF-MUD in combination with Golay codes can provide significantly better results than the other tested spreading codes and receivers. Besides this fact, a failure of Walsh codes especially at the Saleh model of HPA will be outlined by using constellation diagram