Host distance measurement using ICMP protocol in IP networks

Současný Internet se čím dál častěji potýká s problémem správného určení vzdáleností mezi jednotlivými stanicemi. Nejšírší dopad má znalost této veličiny v oblastech optimálního rozložení sítě aplikačního multicastu, správného výběru účastníka peer-to-peer sítě, nebo při prostém rozhodování koncového uživatele, které z nejbližších zrcadel použít pro stažení nějakých dat. Nejbližší v tomto smyslu však nemusí nutně znamenat geograficky nejbližší - vzdálenosti na Internetu jsou typicky vyjadřovány ve veličinách jako je latence nebo šířka pásma. Všechny tyto příklady mají společnou snahu o úsporu šířky pásma a tím pádem ekonomickou úsporu. Metody odhadu pozice v síti pracují na základě měření parametru latence. V této práci budou vytvořeny nástroje pro měření tohoto parametru a zároveň s pomocí těchto nástrojů ukázáno, jak moc spolu korespondují veličiny geografická vzdálenost a latence.Current internet more and more often faces the problem of the right definition of distance between the single hosts. The knowledge of this quantity influences the areas of the optimal lay-out of overlay multicast networks, the right selection of peer-to-peer network participant, or the simple decision of the end user: which one of the nearest mirrors to use for downloading datas. The nearest one doesn't have to mean the nearest in geographical point of view - the distance on Internet is usually expressed by quantities as latency or bandwidth. All these examples have got the saving of bandwidth in common and therefore economical saving. The methods of host position prediction in networks work on the basis of measuring latency parameter. The tools for measuring of this parameter will be set up in this thesis and at the same time it will be shown how geographical distance and latency correspond with each other.

Software support of education in classical cryptoanalysis

Některé z dneších moderních šifrovacích systémů obsahují ve svých základech myšlenky klasických symetrických šifer, jako je např. transpoziční princip v šifře DES. Pro úspěšnou kryptoanalýzu těchto druhů šifer je třeba znát základní krypoanalytické metody. Z toho plyne důležitost výuky klasické kryptoanalýzy - aby studenti co nejlépe pochopili danou problematiku, je třeba použít názorné pomůcky. Tato práce shrnuje poznatky teorie klasické kryptografie a krypotanalýzy vybraných druhů šifer - monoalfabetické a polyalfabetické substituce a dále jednoduché transpozice. Na základě této teorie je vytvořena softwarová podpora výuky klasické kryptoanalýzy - konkrétně formou webových stránek a aplikace umožňující šifrování a luštění klasických druhů šifer.Number of today's modern cipher systems are based on the classical symmetric cipher systems, such as the transposition principle in the DES cipher. Successful analysis and deciphering of these ciphers is therefore underlined by solid knowledge of the elementary cryptanalysis methods. This implies the importance of classical cryptanalysis education -- for better a understanding of the field, using visual means is of utmost importance. The aim of the thesis is to summarize selected cipher methods of the classical cryptanalysis, namely the mono-- and polyalphabetical substitution and transposition route cipher. Along with the theoretical part, ciphering/deciphering software is introduced to be used for educational purposes, particularly a website and a standalone application providing tools for ciphering, analysis and code breaking of the classical cipher based code.

Properties of the loess sediments in Ostrava Region (Czech Republic) and comparison with some other loess sediments

This study deals with a methodical identification and evaluation of physical-mechanical properties of one genetic type of geological structure. This is represented by an engineering-geological zone of eolian sediments, which is regionally rather abundant. The paper contributes to a need to identify typical soil properties for widespread geological environments in a particular region and thus add to good engineering geologists and geotechnical engineers’ awareness in the region. Such information is much required as it permits comparing results of newly conducted engineering-geological investigations and research with the results characteristic for the region in question. It is vital for engineering geologists and geotechnical engineers to be sufficiently informed on the foundation soil properties of widespread geological environments because of professionalism and higher quality of their work results. Comparing other loess sediment studies worldwide it was discovered that the physical properties of the most abundant clays of low to medium plasticity, sandy clays, and sands as foundation soils vary as for the plasticity index, porosity, natural water content, and bulk density to a certain extent but not as significantly as once expected.Web of Scienceart. no. 52943

Influence of the soil genesis on physical and mechanical properties

Thepaper deals with the influence of soil genesis on the physical-mechanical properties.The presented case study was conducted in the region of theOstrava Basinwhere there is a varied genetic composition of the Quaternary geological structure on the underlying Neogeneous sediments which are sediments of analogous granulometry but different genesis. In this study, 7827 soil samples of an eolian, fluvial, glacial, and deluvial origin and their laboratory analyses results were used. The study identified different values in certain cases, mostly in coarser-grained foundation soils, such as sandy loam S4 (MS) and clayey sand F4 (CS). The soils of the fluvial origin manifest different values than other genetic types. Next, based on regression analyses, dependence was proved neither on the deposition depth (depth of samples) nor fromthe point of view of the individual foundation soil classes or the genetic types. The contribution of the paper is to point at the influence of genesis on the foundation soil properties so that engineering geologists and geotechnicians pay more attention to the genesis during engineering-geological and geotechnical investigations.Web of Scienceart. no. 47471

Paramutation of tobacco transgenes by small RNA-mediated transcriptional gene silencing

It has been well established that trans-acting small RNAs guide promoter methylation leading to its inactivation and gene silencing at the transcriptional level (TGS). Here we addressed the question of the influence of the locus structure and epigenetic modifications of the target locus on its susceptibility for being paramutated by trans-acting small RNA molecules. Silencing was induced by crossing a 35S promoter silencer locus 271 with two different 35S-driven transgene loci, locus 2 containing a highly expressed single copy gene and locus 1 containing an inverted posttranscriptionally silenced (PTGS) repeat of this gene. Three generations of exposure to RNA signals from the 271 locus were required to complete silencing and methylation of the 35S promoter within locus 2. Segregating methylated locus 2 epialleles were obtained only from the third generation of hybrids, and this methylation was not correlated with silencing. Strikingly, only one generation was required for the PTGS locus 1 to acquire complete TGS and 35S promoter methylation. In this case, paramutated locus 1 epialleles bearing methylated and inactive 35S promoters segregated already from the first generation of hybrids. The results support the hypothesis that PTGS loci containing a palindrome structure and methylation in the coding region are more sensitive to paramutation by small RNAs and exhibit a strong tendency to formation of meiotically transmissible TGS epialleles. These features contrast with a non-methylated single copy transgenic locus that required several generations of contact with RNA silencing molecules to become imprinted in a stable epiallele

Consumer protection

In this thesis, the reader is familiar with th problems of consumer loans connected with insolvency petition. The thesis contains several chapters and subchapters are dedicated to consumer loans.On the basis of literature and website decribes the development and history of banking, it is defined by consumer credit and its classification and the outline th most important laws. The main goal of this thesis is the analysis of consumer credit, and their effect on the number of insolvency petitions. Practical part is dedicated to free analyzes general analysis of banking and non-banking institutions providing consumer loans and a third analysis focuses on the profile of individual borrowers. Finally, the work is a comparison and evaluation of surveyed data