Transverse Electronic Transport through DNA Nucleotides with Functionalized Graphene Electrodes

Graphene nanogaps and nanopores show potential for the purpose of electrical DNA sequencing, in particular because single-base resolution appears to be readily achievable. Here, we evaluated from first principles the advantages of a nanogap setup with functionalized graphene edges. To this end, we employed density functional theory and the non-equilibrium Green's function method to investigate the transverse conductance properties of the four nucleotides occurring in DNA when located between the opposing functionalized graphene electrodes. In particular, we determined the electrical tunneling current variation as a function of the applied bias and the associated differential conductance at a voltage which appears suitable to distinguish between the four nucleotides. Intriguingly, we observe for one of the nucleotides a negative differential resistance effect.Comment: 19 pages, 7 figure

30 years of collaboration

We highlight some of the most important cornerstones of the long standing and very fruitful collaboration of the Austrian Diophantine Number Theory research group and the Number Theory and Cryptography School of Debrecen. However, we do not plan to be complete in any sense but give some interesting data and selected results that we find particularly nice. At the end we focus on two topics in more details, namely a problem that origins from a conjecture of Rényi and Erdős (on the number of terms of the square of a polynomial) and another one that origins from a question of Zelinsky (on the unit sum number problem). This paper evolved from a plenary invited talk that the authors gaveat the Joint Austrian-Hungarian Mathematical Conference 2015, August 25-27, 2015 in Győr (Hungary)

Market Efficiency after the Financial Crisis: It's Still a Matter of Information Costs

Compared to the worldwide financial carnage that followed the Subprime Crisis of 2007-2008, it may seem of small consequence that it is also said to have demonstrated the bankruptcy of an academic financial institution: the Efficient Capital Market Hypothesis (“ECMH”). Two things make this encounter between theory and seemingly inconvenient facts of consequence. First, the ECMH had moved beyond academia, fueling decades of a deregulatory agenda. Second, when economic theory moves from academics to policy, it also enters the realm of politics, and is inevitably refashioned to serve the goals of political argument. This happened starkly with the ECMH. It was subject to its own bubble – as a result of politics, it expanded from a narrow but important academic theory about the informational underpinnings of market prices to a broad ideological preference for market outcomes over even measured regulation. In this Article we examine the Subprime Crisis as a vehicle to return the ECMH to its information cost roots that support a more modest but sensible regulatory policy. In particular, we argue that the ECMH addresses informational efficiency, which is a relative, not an absolute measure. This focus on informational efficiency leads to a more focused understanding of what went wrong in 2007-2008. Yet informational efficiency is related to fundamental efficiency – if all information relevant to determining a security’s fundamental value is publicly available and the mechanisms by which that information comes to be reflected in the securities market price operate without friction, fundamental and informational efficiency coincide. But where all value relevant information is not publicly available and/or the mechanisms of market efficiency operate with frictions, the coincidence is an empirical question both as to the information efficiency of prices and their relation to fundamental value. Properly framing market efficiency focuses our attention on the frictions that drive a wedge between relative efficiency and efficiency under perfect market conditions. So framed, relative efficiency is a diagnostic tool that identifies the information costs and structural barriers that reduce price efficiency which, in turn, provides part of a realistic regulatory strategy. While it will not prevent future crises, improving the mechanisms of market efficiency will make prices more efficient, frictions more transparent, and the influence of politics on public agencies more observable, which may allow us to catch the next problem earlier. Recall that on September 8, 2008, the Congressional Budget Office publicly stated its uncertainty about whether there would be a recession and predicted 1.5 percent growth in 2009. Eight days later, Lehman Brothers had failed, and AIG was being nationalized

EFEITO DA IDADE NOS DOMÍNIOS COGNITIVO, PSICOLÓGICO E LOCOMOTOR EM IDOSOS DA COMUNIDADE

Introdução: O envelhecimento humano é caracterizado como um processo dinâmico, progressivo e irreversível decorrente de fatores biológicos, psíquicos e sociais. A Organização Mundial da Saúde criou o conceito de capacidade intrínseca (CI), que se caracteriza como sendo o composto de todas as capacidades mentais e físicas que uma pessoa pode recorrer ao longo de sua trajetória. Por fim, salienta-se que o ser humano apresenta uma série de mudanças psicológicas e inúmeros distúrbios do aparelho locomotor derivadas do envelhecimento. Objetivo: Verificar o efeito da idade sobre os domínios cognitivo, psicológico e locomotor em idosos da comunidade. Metodologia: Foi realizado um estudo transversal com 164 idosos de ambos os gêneros. Foram usados como critérios de avaliação um questionário semiestruturado com dados pessoais e foi utilizado o Montreal Cognitive Assessment (MoCA) para avaliar o domínio cognitivo, a Escala de Depressão Geriátrica-15 (GDS-15) para analisar o domínio psicológico e o Short Physical Performance Battery (SPPB) para investigar o domínio locomotor. Os dados foram analisados quanto à normalidade pelo teste de Kolmogorov-Smirnov. As comparações entre as faixas etárias foram feitas pela ANOVA de 1 via, com pós-teste de Bonferroni. Valores de p < 0,05 foram aceitos como significantes. As análises foram feitas pelo software SPSS 20.0. Resultados: Houve efeito da idade nos domínios cognitivo [F(2,161) = 25,982; p < 0,0001] e locomotor [F(2,161) = 11,524; p < 0,0001]. Entretanto, não foi observado efeito da idade no domínio psicológico. Conclusão: Com isso, pode- se concluir que foi encontrado efeito da idade nos domínios cognitivo e locomotor em idosos. Não foi observado efeito da idade sobre o domínio psicológico

Volatility Patterns of CDs, Bond and Stock Markets Before and During the Financial Crisis: Evidence from Major Financial Institutions

This study is motivated by the development of credit-related instruments and signals of stock price movements of large banks during the recent financial crisis. What is common to most of the empirical studies in this field is that they concentrate on modeling the conditional mean. However, financial time series exhibit certain stylized features such as volatility clustering. But very few studies dealing with credit default swaps account for the characteristics of the variances. Our aim is to address this issue and to gain insights on the volatility patterns of CDS spreads, bond yield spreads and stock prices. A generalized autoregressive conditional heteroscedasticity (GARCH) model is applied to the data of four large US banks over the period ranging from January 01, 2006, to December 31, 2009. More specifically, a multivariate GARCH approach fits the data very well and also accounts for the dependency structure of the variables under consideration. With the commonly known shortcomings of credit ratings, the demand for market-based indicators has risen as they can help to assess the creditworthiness of debtors more reliably. The obtained findings suggest that volatility takes a significant higher level in times of crisis. This is particularly evident in the variances of stock returns and CDS spread changes. Furthermore, correlations and covariances are time-varying and also increased in absolute values after the outbreak of the crisis, indicating stronger dependency among the examined variables. Specific events which have a huge impact on the financial markets as a whole (e.g. the collapse of Lehman Brothers) are also visible in the (co)variances and correlations as strong movements in the respective series