Translocation of polymers with folded configurations across nanopores

The transport of polymers with folded configurations across membrane pores is investigated theoretically by analyzing simple discrete stochastic models. The translocation dynamics is viewed as a sequence of two events: motion of the folded segment through the channel followed by the linear part of the polymer. The transition rates vary for the folded and linear segments because of different interactions between the polymer molecule and the pore. It is shown that the translocation time depends non-monotonously on the length of the folded segment for short polymers and weak external fields, while it becomes monotonous for long molecules and large fields. Also, there is a critical interaction between the polymers and the pore that separates two dynamic regimes. For stronger interactions the folded polymer moves slower, while for weaker interactions the linear chain translocation is the fastest. In addition, our calculations show that the folding does not change the translocation scaling properties of the polymer. These phenomena can be explained by the interplay between the translocation distances and transition rates for the folded and linear segments of the polymer. Theoretical results are applied for analysis of experimental translocations through solid-state nanopores.Comment: submitted to J. Chem. Phy

Aproximaciones a la literatura concentracionaria de Max Aub: "Vernet, 1940"; "El limpiabotas del Padre Eterno" y "El cementerio de Djelfa"

El propósito de este trabajo es trazar las particularidades y rasgos comunes entre tres obras cortas pertenecientes al ciclo de obras "El laberinto mágico". Se realiza una aproximación de los aspectos condicionante en el caso de este tipo escritura como la memoria, el olvido y la génesis de la enunciación como una posible catarsis. Primordialmente el análisis se basa en tres obras representativas: "Vernet, 1940", "El limpiabotas del Padre Eterno" y "El cementerio de Djelfa" de Max Aub. Principalmente, se realiza una reflexión en torno a los temas esenciales de la obra como el carácter de testimonio y la construcción de la ficción, así como los efectos de la estancia concentracionaria como la degradación moral, las animalización, cosificación, nihilización y otras particularidades de este discurso concentracionario como tal. También se reflexiona en torno a la figura de Max Aub, similitudes en su biografía con respecto a algunas escenas plasmadas en las obras e posibles influencias de movimientos artísticos y de otras artes. Dichos aspectos quedan argumentados mediante citas textuales de las obras. Asimismo, otros elementos de la obra como la estructura y los recursos específicos de los que se hace uso el autor son tratados con más exhaustividad. Por otro lado, también se remite a otras obras del autor, fuentes bibliográficas y otras producciones de autores afines.The objective of this thesis is to outline the particularities and common features between three short stories which form a part of the fiction cycle “El laberinto mágico” (The Magic Labyrinth). This academic study attempts to approach some of the key aspects which influence this kind of writing such as the importance of memory, forgetfulness and the creation of literature as a possible catharsis. The analysis is based mainly on three representative works: Vernet, 1940, El limpiabotas del Padre Eterno y El cementerio de Djelfa by Max Aub. In general terms an in-depth analysis is being made regarding the essential topics of the work like its testimony essence and fiction construction as well as the effects of the stay in the concentration camps in terms of moral deterioration, animal and object downgrade, nothingness and other features of the literature related to concentration camps. Moreover, a biography analysis of Max Aub’s figure is carried out regarding biography resemblance with some episodes described in his fiction and eventual influences by artistic movements and other kinds of art. These aspects are supported by text quotes from the analyzed works

Effect of Interactions on Molecular Fluxes and Fluctuations in the Transport Across Membrane Channels

Transport of molecules across membrane channels is investigated theoretically using exactly solvable one-dimensional discrete-state stochastic models. An interaction between molecules and membrane pores is modeled via a set of binding sites with different energies. It is shown that the interaction potential strongly influences the particle currents as well as fluctuations in the number of translocated molecules. For small concentration gradients the attractive sites lead to largest currents and fluctuations, while the repulsive interactions yield the largest fluxes and dispersions for large concentration gradients. Interaction energies that lead to maximal currents and maximal fluctuations are the same only for locally symmetric potentials, while they differ for the locally asymmetric potentials. The conditions for the most optimal translocation transport with maximal current and minimal dispersion are discussed. It is argued that in this case the interaction strength is independent of local symmetry of the potential of mean forces. In addition, the effect of the global asymmetry of the interaction potential is investigated, and it is shown that it also strongly affects the particle translocation dynamics. These phenomena can be explained by analyzing the details of the particle entering and leaving the binding sites in the channel.Comment: submitted to J. Chem. Phy

Effect of Inhomogeneity in Translocation of Polymers through Nanopores

The motion of polymers with inhomogeneous structure through nanopores is discussed theoretically. Specifically, we consider the translocation dynamics of polymers consisting of double-stranded and single-stranded blocks. Since only the single-stranded chain can go through the nanopore the double-stranded segment has to unzip before the translocation. Utilizing a simple analytical model, translocation times are calculated explicitly for different polymer orientations, i.e., when the single-stranded block enters the pore first and when the double-stranded segment is a leading one. The dependence of the translocation dynamics on external fields, energy of interaction in the double-stranded segment, size of the polymer and the fraction of double-stranded monomers is analyzed. It is found that the order of entrance into the pore has a significant effect on the translocation dynamics. The theoretical results are discussed using free-energy landscape arguments.Comment: 12 pages, 5 figures, submitted to J. Chem. Phy

Esomeprazole-based sequential therapy and probiotic for Helicobacter pylori eradication

PURPOSE: The objective of the present study was to determine the effectiveness of esomeprazole-based sequential therapy and Bio Gaya probiotic for the treatment of Helicobacter pylori-infection (Hp-infection) with associated gastro duodenal diseases.MATERIAL AND METHODS: The study covered 104 patients with dominating upper dyspeptic syndrome and Hp-infection examined by means of two or more methods. Esomeprazole-based sequential therapy consisted in amoxicillin in a dose of 1.0 g two times daily for the first five days followed by clarithromycin and metronidazole in a dose of 500 mg two times daily for the next 5 days. A Bio Gaya probiotic was added during the 10-day treatment.RESULTS: Hp-infection was successfully treated in 98 patients (94.2%) and in 79 out of 81 naive ones (97% of the cases). This therapy proved effective in 19 out of 23 patients (82.6%) after one or two failed Hp-infection eradications, too. The treatment failed in 6 patients (5.7%) because of a double antibiotic resistance.CONCLUSION: The esomeprazole-based sequential therapy and Bio Gaya probiotic represented a highly and well-tolerable effective eradication option. Clinical symptoms and quality of life were favourable influenced in all the patients as well as side effects were rare.Scripta Scientifica Medica 2013; 45(2): 61-65

Recent trends in state of landscapes and shoreline dynamics in the Bulgarian sector of the Black Sea

The article analyzes the contemporary processes of natural and human-induced shore- line dynamics between cape Kaliakra and cape Emine, Bulgarian Black Sea coastal zone. Main accent is put on the anthropogenic impact on beach morphodynamics, coastal erosion, sediment transport and accretion influenced by land use changes and technogenic load. The stages of recent landscape transformations since the beginning of the XX century are discussed chronologically. Assumptions are made with reference to existing relationships among coastal geomorphic processes, land use dynamics, levels of anthropogenization and coastal landscape change at the investigated area.Проанализировано современные процессы естественной и подверженной антропогенному влиянию динамики береговой линии между мысом Калиакра и мысом Емине на болгарском побережье Черного моря. Основное внимание уделено воздействию антропогенных факторов на береговую морфодинамику, прибрежную эрозию, транспортировку и аккумуляцию осадков под влиянием изменений в использовании земель и техногенной нагрузки. Стадии недавних преобразований ландшафта с начала XX столетия рассмотрены хронологически. Сделаны выводы о взаимоотношениях прибрежных процессов, геоморфологии, динамики использования земли, уровня антропогенизации и изменения прибрежного ландшафта на исследованной территории.Проаналізовано сучасні процеси природної і зазнавшої антропогенного впливу динаміки берегової лінії між мисом Каліакра і мисом Еміне на болгарському узбережжі Чорного моря. Основну увагу приділено впливу антропогенних чинників на берегову морфодинаміку, прибережну ерозію, транспортування й акумуляцію осадів під впливом змін у використанні земель і техногенного навантаження. Стадії недавніх перетворень ландшафту з початку XX сторіччя розглянуто хронологічно. Зроблено висновки про взаємовідношення прибережних процесів, геоморфології, динаміки використання землі, рівня антропогенізації та зміни прибережного ландшафту на дослідженій території

Serbia and the NATO Partnership for Peace program

This thesis explores Serbia's relationship with NATO, focusing on two questions: How can Serbia and NATO benefit from the Partnership for Peace program? How can Serbia identify its needs for assistance as a consumer of security and also actively contribute to regional security under the overarching PfP program? Serbia's main problems include: (1) weak civilian control of the military and intelligence services, (2) inadequate legal basis and appropriate legislation for effective leadership to transform the military and intelligence services, and (3) a deeply troubled heritage stemming from the period when Milosevic was in power. Serbia's PfP membership can most directly benefit state authorities by providing expert support for solving the first two problems. These problems can be resolved with a clearly defined security policy and effective mechanisms for implementing it. Serbian participation in the NATO PfP program cannot solve the third security issue, because NATO's role in regard to war criminals and Kosovo's final status is to support the UN. However, PfP membership provides an additional forum for governments to openly discuss, as equals, issues like the territorial integrity of Serbia and war crime convictions.http://archive.org/details/serbiandnatopart109454213Bulgarian Air Force author.Approved for public release; distribution is unlimited