Influence of the buffer environment on the Relative Biological Effectiveness of carbon ion radiation, investigated by Scanning Force Microscopy and gel electrophoresis

This work focuses on the analysis of the influence of environment on the relative biological effectiveness (RBE) of carbon ions on molecular level. Due to the high relevance of RBE for medical applications, such as tumor therapy, and radiation protection in space, DNA damages have been investigated in order to understand the biological efficiency of heavy ion radiation. The contribution of this study to the radiobiology research consists in the analysis of plasmid DNA damages induced by carbon ion radiation in biochemical buffer environments, as well as in the calculation of the RBE of carbon ions on DNA level by mean of scanning force microscopy (SFM). In order to study the DNA damages, besides the common electrophoresis method, a new approach has been developed by using SFM. The latter method allows direct visualisation and measurement of individual DNA fragments with an accuracy of several nanometres. In addition, comparison of the results obtained by SFM and agarose gel electrophoresis methods has been performed in the present study. Sparsely ionising radiation, such as X-rays, and densely ionising radiation, such as carbon ions, have been used to irradiate plasmid DNA in trishydroxymethylaminomethane (Tris buffer) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES buffer) environments. These buffer environments exhibit different scavenging capacities for hydroxyl radical (HO0), which is produced by ionisation of water and plays the major role in the indirect DNA damage processes. Fragment distributions have been measured by SFM over a large length range, and as expected, a significantly higher degree of DNA damages was observed for increasing dose. Also a higher amount of double-strand breaks (DSBs) was observed after irradiation with carbon ions compared to X-ray irradiation. The results obtained from SFM measurements show that both types of radiation induce multiple fragmentation of the plasmid DNA in the dose range from D = 250 Gy to D = 1500 Gy. Using Tris environments at two different concentrations, a decrease of the relative biological effectiveness with the rise of Tris concentration was observed. This demonstrates the radioprotective behavior of the Tris buffer solution. In contrast, a lower scavenging capacity for all other free radicals and ions, produced by the ionisation of water, was registered in the case of HEPES buffer compared to Tris solution. This is reflected in the higher RBE values deduced from SFM and gel electrophoresis measurements after irradiation of the plasmid DNA in 20 mM HEPES environment compared to 92 mM Tris solution. These results show that HEPES and Tris environments play a major role on preventing the indirect DNA damages induced by ionising radiation and on the relative biological effectiveness of heavy ion radiation. In general, the RBE calculated from the SFM measurements presents higher values compared to gel electrophoresis data, for plasmids irradiated in all environments. Using a large set of data, obtained from the SFM measurements, it was possible to calculate the survive rate over a larger range, from 88% to 98%, while for gel electrophoresis measurements the survive rates have been calculated only for values between 96% and 99%. While the gel electrophoresis measurements provide information only about the percentage of plasmids DNA that suffered a single DSB, SFM can count the small plasmid fragments produced by multiple DSBs induced in a single plasmid. Consequently, SFM generates more detailed information regarding the amount of the induced DSBs compared to gel electrophoresis, and therefore, RBE can be calculated with more accuracy. Thus, SFM has been proven to be a more precise method to characterize on molecular level the DNA damage induced by ionizing radiations.

Supramolecular order and dynamics of functional materials studied by solid state NMR

The goal of this thesis was the investigation of the structure, conformation, supramolecular order and molecular dynamics of different classes of functional materials (phthalocyanine, perylene and hexa-peri-hexabenzocoronene derivatives and mixtures of those), all having planar aromatic cores modified with various types of alkyl chains. The planar aromatic systems are known to stack in the solid and the liquid-crystalline state due to p-p interactions forming columnar superstructures with high one-dimensional charge carrier mobility and potential application in photovoltaic devices. The different functionalities attached to the aromatic cores significantly influence the behavior of these systems allowing the experimentalists to modify the structures to fine-tune the desired thermotropic properties or charge carrier mobility. The aim of the presented studies was to understand the interplay between the driving forces causing self-assembly by relating the structural and dynamic information about the investigated systems. The supramolecular organization is investigated by applying 1H solid state NMR recoupling techniques. The results are related with DSC and X-ray scattering data. Detailed information about the site-specific molecular dynamics is gained by recording spinning sideband patterns using 1H-1H and 13C-1H solid state NMR recoupling techniques. The determined dipole-dipole coupling constants are then related with the coupling constants of the respective rigid pairs, thus providing local dynamic order parameters for the respective moieties. The investigations presented reveal that in the crystalline state the preferred arrangement in the columnar stack of discotic molecules modified with alkyl chains is tilted. This leads to characteristic differences in the 1H chemical shifts of otherwise chemically equivalent protons. Introducing branches and increasing the length of the alkyl chains results in lower mesophase transitions and disordered columnar stacks. In the liquid-crystalline state some of the discs lose the tilted orientation, others do not, but all start a rapid rotation about the columnar axis.

p19ARF targets certain E2F species for degradation

p19ARF suppresses the growth of cells lacking p53 through an unknown mechanism. p19ARF was found to complex with transcription factors E2F1, -2, and -3. Levels of endogenous or ectopically expressed E2F1, -2, and -3, but not E2F6, were reduced after synthesis of p19ARF, through a mechanism involving increased turnover. p19ARF-induced degradation of E2F1 depended on a functional proteasome, and E2F1 was relocalized to nucleoli when coexpressed with p19ARF. Consistent with reduced levels of E2F1 and E2F3, the proliferation of cells defective for p53 function was suppressed by p19ARF, and the effect was partially reversed by ectopic overexpression of E2F1. These results suggest a broader role for p19ARF as a tumor suppressor, in which targeting of certain E2F species may cooperate with stimulation of the p53 pathway to counteract oncogenic growth signals.

Michail Kogălniceanu: discurs de recepţiune rostit in şedinţă solemnă sub preşidenţa M.S. Regelui la 17 martie 1895. Cu rĕspunsuld-lui Dimitrie A. Sturdza.

Mode of access: Internet.

Genealogia Cantacuzinilor;

Mode of access: Internet.

Die Pferdezucht in Rumanien unter besonderer Berucksichtigung ihrer Rentabilitat.

Thesis (doctoral)--Universitat Leipzig.

Extending Object-Oriented Network Protocols via alternative Transportation Bindings (Web Services over XMPP)

Distributed and/or composite web applications are driven by intercommunication via web services, which employ application-level protocols, such as SOAP. However, these protocols usually rely on the classic HTTP for transportation. HTTP is quite efficient for what it does — delivering web page content, but has never been intended to carry complex web service oriented communication. Today there exist modern protocols that are much better fit for the job. Such a candidate is XMPP. It is an XML-based, asynchronous, open protocol that has built-in security and authentication mechanisms and utilizes a network of federated servers. Sophisticated asynchronous multi-party communication patterns can be established, effectively aiding web service developers. This paper’s purpose is to prove by facts, comparisons, and practical examples that XMPP is not only better suited than HTTP to serve as middleware for web service protocols, but can also contribute to the overall development state of web services.

2D Apportionment Methods

Михаил Константинов, Костадин Янев, Галина Пелова, Юлиана Бонева - В работата се разглеждат двумерни пропорционални изборни системи, при които броят на партийните мандати се определя на национално ниво, а персонификацията на мандатите става чрез регионални партийни листи. При това, броят на мандатите във всеки район се определя пропорционално на населението. Предложени са нови подобрени методи за двумерно разпределение и са представени резултати от числени пресмятания с данните от парламентарните избори през 2009 г.

Използване на системата MATLAB в техническите университети

Mihail Konstantinov, Vladimir Todorov, Galina Pelova, Juliana Boneva - We consider some aspect of the mathematical education in technical universities using MATLAB. Special attention is paid to the subjects Analytical Geometry and Differential Equations.

Loss of Accuracy in Numerical Computations

Михаил М. Константинов, Петко Х. Петков - Разгледани са възможните катастрофални ефекти от неправилното използване на крайна машинна аритметика с плаваща точка. За съжаление, тази тема не винаги се разбира достатъчно добре от студентите по приложна и изчислителна математика, като положението в инженерните и икономическите специалности в никакъв случай не е по-добро. За преодоляване на този образователен пропуск тук сме разгледали главните виновници за загубата на точност при числените компютърни пресмятания. Надяваме се, че представените резултати ще помогнат на студентите и лекторите за по-добро разбиране и съответно за избягване на основните фактори, които могат да разрушат точността при компютърните числени пресмятания. Последното не е маловажно – числените катастрофи понякога стават истински, с големи щети и човешки жертви.

Numerical Issues in Using MATLAB

Михаил Константинов, Весела Пашева, Петко Петков - Разгледани са някои числени проблеми при използването на компютърната система MATLAB в учебната дейност: пресмятане на тригонометрични функции, повдигане на матрица на степен, спектрален анализ на целочислени матрици от нисък ред и пресмятане на корените на алгебрични уравнения. Причините за възникналите числени трудности могат да се обяснят с особеностите на използваната двоичната аритметика с плаваща точка.

Primary data sets of the hydrographic atlas of the Southern Ocean

The general knowledge of the hydrographic structure of the Southern Ocean is still rather incomplete since observations particularly in the ice covered regions are cumbersome to be carried out. But we know from the available information that thermohaline processes have large amplitudes and cover a wide range of scales in this part of the world ocean. The modification of water masses around Antarctica have indeed a worldwide impact, these processes ultimately determine the cold state of the present climate in the world ocean. We have converted efforts of the German and Russian polar research institutions to collect and validate the presently available temperature, salinity and oxygen data of the ocean south of 30°S latitude. We have carried out this work in spite of the fact that the hydrographic programme of the World Ocean Circulation Experiment (WOCE) will provide more new information in due time, but its contribution to the high latitudes of the Southern Ocean is quite sparse. The modified picture of the hydrographic structure of the Southern Ocean presented in this atlas may serve the oceanographic community in many ways and help to unravel the role of this ocean in the global climate system. This atlas could only be prepared with the altruistic assistance of many colleagues from various institutions worldwide who have provided us with their data and their advice. Their generous help is gratefully acknowledged. During two years scientists from the Arctic and Antarctic Research Institute in St. Petersburg and the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven have cooperated in a fruitful way to establish the atlas and the archive of about 38749 validated hydrographic stations. We hope that both sources of information will be widely applied for future ocean studies and will serve as a reference state for global change considerations.

Miten yhdeksäsluokkalaiset kirjoittavat kielestä? Kielitietoisuuden rakentuminen kirjoittamalla

Tässä tutkielmassa selvitän, mitä kielitietoisuus käytännössä tarkoittaa ja miten sitä voidaan rakentaa kielen avulla. Aineistonani käytän kahdessa varsinaissuomalaisessa koulussa teettämiäni kirjoitelmia sekä opetusryhmissä seuraamillani tunneilla kirjoitettuja kenttämuistiinpanoja. Analysoin kirjoitelmia sisällönanalyyttisesti sekä dialogisen ja poststrukturalistisen analyysin avulla. Lähtökohtana tutkimukselleni ovat uudet perusopetuksen opetussuunnitelman perusteet, jotka otetaan käyttöön porrastetusti elokuusta 2016 lähtien. Uudessa opetus¬suunnitelmassa huomioidaan erityisesti kielitietoisuus, eli kouluista pyritään tekemään kielitietoisia yhteisöjä, joissa kielistä puhutaan avoimesti ja kielten merkitys tunnustetaan aiempaa laajemmin. Tutkimukseni teoriataustana käytän Lev Vygotskin sosiokulttuurista näkemystä kielestä ja tietoisuudesta ja Mihail Bahtinin dialogista kielikäsitystä. Vygotskin ja Bahtinin mukaan merkitykset rakentuvat sosiaalisessa vuorovaikutuksessa. Ihmisen tietoisuus ei ole yksi ja pysyvä kokonaisuus, vaan se on moniääninen ja jatkuvasti muuttuva. Moniäänisyydellä Bahtin tarkoittaa sitä, että tietoisuus muodostuu erilaisten äänten välisestä dialogista. Yksilön tietoisuuteen vaikuttavat siis tilannekohtaisten muuttujien lisäksi kaikki aiemmat vuorovaikutustilanteet. Tutkimusaineistoani analysoimalla selvitin, että oppilaiden kielitietoisuus on hyvin moniääninen, sillä siihen vaikuttavat niin koulu, media, koti kuin kaveritkin. Oppilaiden tietoisuuksissa kuuluu monia autoritaarisia ääniä, jotka vaikuttavat oppilaiden käsityksiin ja asettavat oppilaiden kielenkäytölle erilaisia rajoituksia. Oppilaiden kielitietoisuus on myös hyvin monikielinen, sillä oppilaat kuulevat ja käyttävät päivittäin monia kieliä sekä kavereiden ja perheen kesken että medioiden parissa. Tietoisuus ympäristön moni-kielisyydestä näytti kirjoitelmien perusteella rakentuvan kirjoittamisen edetessä. Dialogista ja poststrukturalistista analyysia on aiemmin sovellettu lähinnä toisen kielen oppimisen konteksteissa ja kieli-identiteetin tutkimuksessa. Ne sopivat kuitenkin hyvin myös nuorten kielitietoisuuden tutkimiseen laajemmassa kielenkäytön kontekstissa, ja rinnakkain sovellettuna analyysimetodit tukivat hyvin toisiaan. Tutkimuksellani pyrin tarjoamaan konkreettisia välineitä kielitietoisuuden edistämiseksi kouluissa. Kirjoitelmien tehtävänannon tyyppinen kirjoitustehtävä auttoi hyvin oppilaita erittelemään kielellistä ympäristöään ja omia käsityksiään kielistä. Jatkossa voisi tutkia, miten uusi opetussuunnitelma on vaikuttanut koulujen ilmapiiriin ja ovatko myöhemmät ikäluokat taitavampia erittelemään kielenkäyttöään ja kieliä koskevia käsityksiään.