Cytochrome b haplotype divergences in West European Apodemus

Sequencing of the cytochrome b mitochondrial gene (732 base pairs) in samples of Apodemus sylvaticus from Central Europe (eastern France, Switzerland, southern Germany and western Austria) revealed significant molecular variation not reflected in previous morphological and genetic studies of this species. A comparison with the sequences (150 bp) of 54 specimens available from GenBank (NCBI) showed that two problematic individuals originating from southern Germany have to be assigned to A. fulvipectus, a species not yet known in western Europe. A. sylvaticus specimens (n = 14) sampled north of the Alps exhibited a maximum intraspecific sequence divergence of about 5.1%, whereas the maximum divergence is much Lower in A. flavicollis (1%, n = 5) and in A. alpicola (0.5%, n = 4), although the samples originate from a similar geographic range of about 350 km. We also found a high rate of erroneously assigned specimens in GenBank, which indicates that the discrimination of Apodemus species remains a problem and requires further investigations.

Shot-noise suppression in Schottky barrier diodes

We give a theoretical interpretation of the noise properties of Schottky barrier diodes based on the role played by the long range Coulomb interaction. We show that at low bias Schottky diodes display shot noise because the presence of the depletion layer makes the effects of the Coulomb interaction negligible on the current fluctuations. When the device passes from barrier to flat band conditions, the Coulomb interaction becomes active, thus introducing correlation between different current fluctuations. Therefore, the crossover between shot and thermal noise represents the suppression due to long range Coulomb interaction of the otherwise full shot noise. Similar ideas can be used to interpret the noise properties of other semiconductor devices.

Higher-order colored-noise effects in multivariable systems

We extend the partial resummation technique of Fokker-Planck terms for multivariable stochastic differential equations with colored noise. As an example, a model system of a Brownian particle with colored noise is studied. We prove that the asymmetric behavior found in analog simulations is due to higher-order terms which are left out in that technique. On the contrary, the systematic ¿-expansion approach can explain the analog results.

Three essays in risk management in financial institutions

The choice to adopt risk-sensitive measurement approaches for operational risks: the case of Advanced Measurement Approach under Basel II New Capital Accord This paper investigates the choice of the operational risk approach under Basel II requirements and whether the adoption of advanced risk measurement approaches allows banks to save capital. Among the three possible approaches for operational risk measurement, the Advanced Measurement Approach (AMA) is the most sophisticated and requires the use of historical loss data, the application of statistical tools, and the engagement of a highly qualified staff. Our results provide evidence that the adoption of AMA is contingent on the availability of bank resources and prior experience in risk-sensitive operational risk measurement practices. Moreover, banks that choose AMA exhibit low requirements for capital and, as a result might gain a competitive advantage compared to banks that opt for less sophisticated approaches. - Internal Risk Controls and their Impact on Bank Solvency Recent cases in financial sector showed the importance of risk management controls on risk taking and firm performance. Despite advances in the design and implementation of risk management mechanisms, there is little research on their impact on behavior and performance of firms. Based on data from a sample of 88 banks covering the period between 2004 and 2010, we provide evidence that internal risk controls impact the solvency of banks. In addition, our results show that the level of internal risk controls leads to a higher degree of solvency in banks with a major shareholder in contrast to widely-held banks. However, the relationship between internal risk controls and bank solvency is negatively affected by BHC growth strategies and external restrictions on bank activities, while the higher regulatory requirements for bank capital moderates positively this relationship. - The Impact of the Sophistication of Risk Measurement Approaches under Basel II on Bank Holding Companies Value Previous research showed the importance of external regulation on banks' behavior. Some inefficient standards may accentuate risk-taking in banks and provoke a financial crisis. Despite the growing literature on the potential effects of Basel II rules, there is little empirical research on the efficiency of risk-sensitive capital measurement approaches and their impact on bank profitability and market valuation. Based on data from a sample of 66 banks covering the period between 2008 and 2010, we provide evidence that prudential ratios computed under Basel II standards predict the value of banks. However, this relation is contingent on the degree of sophistication of risk measurement approaches that banks apply. Capital ratios are effective in predicting bank market valuation when banks adopt the advanced approaches to compute the value of their risk-weighted assets.

Effect of External Noise Correlation in Optical Coherence Resonance

Coherence resonance occurring in semiconductor lasers with optical feedback is studied via the Lang-Kobayashi model with external nonwhite noise in the pumping current. The temporal correlation and the amplitude of the noise have a highly relevant influence in the system, leading to an optimal coherent response for suitable values of both the noise amplitude and correlation time. This phenomenon is quantitatively characterized by means of several statistical measures.