Surrogate Data Analysis and Stochastic Chaotic Modelling: Application to Stock Exchange Returns Series

We investigate for evidence of complex-deterministic dynamics in financial returns time series. By combining the Surrogate Data Analysis inferential framework with the MG-GARCH (Kyrtsou and Terraza, 2003) modelling approach, we examine whether the sequences are characterized by aperiodic and nonlinear deterministic cycles or pure randomness. Our results support the hypothesis of complex nonlinear and non-stochastic dynamics in the data generating processes. According to our approach, markets can be assumed to be highly complex, high-dimensional, open and dissipative dynamical systems that need feedback as well as other kinds of inputs in order to operate. These inputs may come in the guise of noise or news. The inputs may also control the evolution of the system dynamics and the knowledge of their nature may allow us to forecast the future states of the market with greater accuracy. To this extent the MG-GARCH model provides a valuable insight on how a feedback mechanism can operate within the structure of stock returns processes and explain stylized facts.MG-GARCH, Surrogate Data Analysis, Chaos, Complexity

Formal security analysis of registration protocols for interactive systems: a methodology and a case of study

In this work we present and formally analyze CHAT-SRP (CHAos based Tickets-Secure Registration Protocol), a protocol to provide interactive and collaborative platforms with a cryptographically robust solution to classical security issues. Namely, we focus on the secrecy and authenticity properties while keeping a high usability. In this sense, users are forced to blindly trust the system administrators and developers. Moreover, as far as we know, the use of formal methodologies for the verification of security properties of communication protocols isn't yet a common practice. We propose here a methodology to fill this gap, i.e., to analyse both the security of the proposed protocol and the pertinence of the underlying premises. In this concern, we propose the definition and formal evaluation of a protocol for the distribution of digital identities. Once distributed, these identities can be used to verify integrity and source of information. We base our security analysis on tools for automatic verification of security protocols widely accepted by the scientific community, and on the principles they are based upon. In addition, it is assumed perfect cryptographic primitives in order to focus the analysis on the exchange of protocol messages. The main property of our protocol is the incorporation of tickets, created using digests of chaos based nonces (numbers used only once) and users' personal data. Combined with a multichannel authentication scheme with some previous knowledge, these tickets provide security during the whole protocol by univocally linking each registering user with a single request. [..]Comment: 32 pages, 7 figures, 8 listings, 1 tabl

Cooperation between librarians and teaching staff

The changing times with new challenges and new need means that university libraries must look closely at their own visions and missions. The libraries must be ready to accept new tasks and cover the needs of the student’s and academic staff in new areas. In this paper I will look at the need for cooperation between librarians and academic staff in order to optimize the teaching of information literacy in the library, and also present the on-line tutorial Search and Write

What´s new and useful about chaos in economic science

La complejidad es una de las propiedades características del comportamiento económico. En este trabajo se exponen los principales conceptos y técnicas de la teoría del caos, analizando las distintas áreas de la ciencia económica desde el punto de vista de la complejidad y el caos. [ABSTRACT] Complexity is one of the most important characteristic properties of the economic behaviour. The new field of knowledge called Chaotic Dynamic Economics born precisely with the objective of understanding, structuring and explaining in an endogenous way such complexity. In this paper, and after scanning the principal concepts and techniques of the chaos theory, we analyze, principally, the different areas of Economic Science from the point of view of complexity and chaos, the main and most recent researches, and the present situation about the results and possibilities of achieving an useful application of those techniques and concepts in our field

Localization of peroxidase enzyme in the bark of Hevea brasiliensis and its implication in anatomy

Localization of peroxidase enzyme with respect to seasons has been carried out in the bark of mature trees of Hevea brasiliensis using guaiacol and hydrogen peroxide as the substrate. Cell walls of sieve tubes including sieve plates, and cytoplasm of phloic rays both in the soft and hard region of the bark showed positive indication of peroxidase activity with reddish brown coloration. Sieve tubes differentiated recently from the derivatives of cambium also stained deeply. The cell wall of the phloic rays remained passive for peroxidase activity but the cytoplasm appeared to be granulated and was in a state of streaming motion which was evident in cross sectional view of the bark. Companion cells did not give any indication of peroxidase activity but it was localized in the intercellular spaces of axial parenchyma cells in the soft bark. Phloic rays exhibited seasonal variation for peroxidase enzyme while the activity was localized throughout the year in the sieve tubes. In the samples taken during December- January, phloic rays were unstained throughout the bark. Bark samples collected in the month of March and April showed deep coloration for phloic rays extending from the phellogen to the periphery of the cambial zone. In the month of June, the partially differentiated phloic rays in the cambial zone stained for peroxidase and subsequently differentiated ones were completely unstained. The phloic rays in the months of September and October remain unstained in the soft bark while it gave a brown coloration in the hard bark region