Evaluating two implementations of the component responsible for decoding video and audio in the Brazilian digital TV middleware

The project Ginga Code Development Network (GingaCDN) was created to implement a reference version of Ginga, the Brazilian Digital Television System (SBTVD) middleware, supporting the declarative GingaNCL and the procedural GingaJ environments in the same middleware. To reach that, a common core is being implemented, named Ginga Common Core (GingaCC). One of the main components of the GingaCC is the one responsible to decode audio and video streams, called Media Processing. In this work, two Media Processing implementations using libVLC and Xine graphical libraries are investigated. Performance tests and results of both Media Processing implementations running in two different desktop architectures are discussed.     

On computing the entropy of cellular automata

We study the topological entropy of a particular class of dynamical systems: cellular automata. The topological entropy of a dynamical system (X,F) is a measure of the complexity of the dynamics of F over the space X. The problem of computing (or even approximating) the topological entropy of a given cellular automata is algorithmically undecidable (Ergodic Theory Dynamical Systems 12 (1992) 255). In this paper, we show how to compute the entropy of two important classes of cellular automata namely, linear and positively expansive cellular automata. In particular, we prove a closed formula for the topological entropy of D-dimensional (D1) linear cellular automata over the ring Z_m (m2) and we provide an algorithm for computing the topological entropy of positively expansive cellular automata.     

Active Integrity Constraints for Database Consistency Maintenance

This paper introduces active integrity constraints (AICs), an extension of integrity constraints for consistent database maintenance. An active integrity constraint is a special constraint whose body contains a conjunction of literals which must be false and whose head contains a disjunction of update actions representing actions (insertions and deletions of tuples) to be performed if the constraint is not satisfied (that is its body is true). The AICs work in a domino-like manner as the satisfaction of one AIC may trigger the violation and therefore the activation of another one. The paper also introduces founded repairs, which are minimal sets of update actions that make the database consistent, and are specified and “supported” by active integrity constraints. The paper presents: 1) a formal declarative semantics allowing the computation of founded repairs and 2) a characterization of this semantics obtained by rewriting active integrity constraints into disjunctive logic rules, so that founded repairs can be derived from the answer sets of the derived logic program. Finally, the paper studies the computational complexity of computing founded repairs.     

ChangeLedge: Change design and planning in networked systems based on reuse of knowledge and automation

Proper management of Information Technology (IT) resources and services has become imperative for the success of modern organizations. The IT Infrastructure Library (ITIL) represents, in this context, the most widely accepted framework to help achieve this end. Among the processes that compose ITIL, change management has an important role in defining best practices and processes for the efficient and prompt handling of IT changes. In practice, however, such changes are usually described and documented in an ad hoc fashion, due to the lack of proper support to assist the design process. This hampers knowledge acquired when specifying, planning, and carrying out previous changes to be reused in subsequent requests, even though such reuse may result in fewer incidents and faster specification of change plans. To address this problem, in this paper we present a conceptual solution to support the design and planning of IT changes and explore the concept of change templates as a mechanism to formalize, preserve, and (re)use knowledge in the specification of (recurrent and similar) IT changes. To prove concept and technical feasibility of the proposed solution, we have developed a prototypical implementation of a change management system called ChangeLedge and used it to carry out a set of experiments, considering typical IT changes. The results obtained indicate the effectiveness and efficiency of the system, which is able to generate accurate and actionable change plans in substantially less time than would be spent by a skilled human operator.     

Obtaining linguistic fuzzy rule-based regression models from imprecise data with multiobjective genetic algorithms

Backfitting of fuzzy rules is an Iterative Rule Learning technique for obtaining the knowledge base of a fuzzy rule-based system in regression problems. It consists in fitting one fuzzy rule to the data, and replacing the whole training set by the residual of the approximation. The obtained rule is added to the knowledge base, and the process is repeated until the residual is zero, or near zero. Such a design has been extended to imprecise data for which the observation error is small. Nevertheless, when this error is moderate or high, the learning can stop early. In this kind of algorithms, the specificity of the residual might decrease when a new rule is added. There may happen that the residual grows so wide that it covers the value zero for all points (thus the algorithm stops), but we have not yet extracted all the information available in the dataset. Focusing on this problem, this paper is about datasets with medium to high discrepancies between the observed and the actual values of the variables, such as those containing missing values and coarsely discretized data. We will show that the quality of the iterative learning degrades in this kind of problems, because it does not make full use of all the available information. As an alternative to sequentially obtaining rules, we propose a new multiobjective Genetic Cooperative Competitive Learning (GCCL) algorithm. In our approach, each individual in the population codifies one rule, which competes in the population in terms of maximum coverage and fitting, while the individuals in the population cooperate to form the knowledge base.

---

Powerful and flexible fuzzy algorithm for nonlinear dynamic systemidentification

A new powerful and flexible fuzzy algorithm for nonlinear dynamic system identification is presented. It is based on the identification of the derivative of the system state, instead of the future system state. The membership functions of the underlying static fuzzy model are two-sided Gaussian functions and the learning algorithm is a hybrid-nested routine based on least-squares, quasi-Newton and simplex optimization methods. Moreover, a simple clustering algorithm based on an additional higher level fuzzy model is proposed. The application to the identification of the Mackey-Glass chaotic time series is presented and compared with previous results in terms of maximum error and nondimensional error index. Finally, the application to a test nonlinear dynamic system is presented to show the capabilities of the clustering algorithm. The obtained results show that the proposed algorithm can find wide application in practical problems, such as in nonlinear electronic circuit design     

Exact and Approximate Truthful Mechanisms for the Shortest Paths Tree Problem

Let a communication network be modeled by an undirected graph G=(V,E) of n nodes and m edges, and assume that edges are controlled by selfish agents. In this paper we analyze the problem of designing a truthful mechanism for computing one of the most popular structures in communication networks, i.e., the single-source shortest paths tree. More precisely, we will study several realistic scenarios, in which each agent can own either a single or multiple edges of G. In particular, for the single-edge case, we will show that: (i) in the classic utilitarian case, the problem can be solved efficiently in O(mnlog α(m,n)) time, where α(m,n) is the inverse of the Ackermann’s function; (ii) in a meaningful non-utilitarian case, namely that in which agents’ valuation functions only depend on the edge lengths, the problem can be solved in O(m+nlog n) time. Conversely, for the multiple-edges case, we will show in the utilitarian case an O(mP+nPlog n) time truthful mechanism, where P=O(n) denotes the number of agents participating in the solution, while in the same non-utilitarian case we will prove a general lower bound to the approximation ratio that can be achieved by any truthful mechanism, by showing that no c-approximate mechanism can exist, for any fixed . Work partially supported by the Research Project GRID.IT, funded by the Italian Ministry of Education, University and Research. Part of the results herein contained was presented at the 11th International Euro-Par Conference (Euro-Par’05), Lisbon, Portugal, 2005.     

Molecular dynamics and circular dichroism studies of human and rat C-peptides

Proinsulin C-peptide has been recently described as an endogenous peptide hormone, responsible for important physiological functions others than its role in proinsulin processing. Accumulating evidences that C-peptide exerts beneficial effects in the treatment of long term complications of patients with type 1 diabetes mellitus indicate that this molecule may be administered together with insulin in future therapies. Despite its clear pharmacological interest, the secondary and three-dimensional (3D) structures of human C-peptide are still points of controversy. In the present work we report molecular dynamics (MD) simulations of human, rat I and rat II C-peptides. A common experimental strategy applied to all peptides consisted of homology building followed by multinanosecond MD simulations in vacuum and water. Circular dichroism (CD) experiments of each peptide in the absence and presence of 2,2,2-trifluoroethanol (TFE) were performed to support validation of the theoretical models. A multiple sequence alignment of 23 known mammalian C-peptides was constructed to identify significant conserved sites that would be important for the maintenance of secondary and tertiary structures. The analysis of the molecular dynamics trajectories for the human, rat I and rat II molecules have shown quite different general behavior, being the human C-peptide more flexible than the two others. Human and rat C-peptides exhibit very stable turn-like structures at the middle and C-terminal regions, which have been described as potential active sites of C-peptides. Human C-peptide also presented a short alpha-helix throughout the MD, which was not found in the rat molecules. CD data is in very good agreement with the MD results and both methods were able to identify a greater structural stability and potential in rat C-peptides when compared to the human C-peptide. The simulation results are discussed and validated in the light of multiple sequence alignment, recent experimental data from the literature and our own CD experiments.     

The occurrence of long chain α,ω-diols in the lipids of steer and human meibomian glands

A group of long chain α,ω-diols (C₂₉ to C₃₄) has been identified in the lipids of steer and human meibomian gland excreta (meibum). These new lipids were isolated from the steer meibum unsaponifiables. Proof of structure was provided by 1) the column chromatographic behavior and TLC of the diols and their diacetates; 2) GLC on glass capillary columns; 3) fragmentation patterns in GC-MS; 4) NMR data, and 5) ozonolysis studies of the unsaturates. Chain types for the steer sample were 51% straight monoenes, 8.5% straight saturates, 39% iso and anteiso saturates and 1.5% iso and anteiso unsaturates. GC for the human sample gave straight monoenes 83%, straight saturates 8%, and iso plus anteiso saturates 9%. Close correspondence of the α,ω-diol chain lengths and types with meibum ω-hydroxy fatty acids suggests a biochemical precursor relationship.     

Pollution of mussels by particulate lead from sea water

Summary The accumulation of > 0.8 gm lead containing, suspended particles from polluted sea water in mussel (Mytillus galloprovincialis Lamarck) was studied. Lead was determined in the ash of the edible part of the mussel by a voltammetric macromethod. Atomic absorption spectroscopy was used for determining particulate lead in sea water. The statistically significant linear regression, observed for lead in mussel on lead in sea water, indicates that a fraction of lead found in the mollusc has a particulate origin, with an enrichment factor of about 2300.

---

Verunreinigungen von Miesmuscheln durch bleihaltige Partikel aus Seewasser

Zusammenfassung Die Aufnahme von bleihaltigen Partikeln aus verunreinigtem Seewasser durch Miesmuscheln (Mytilus galloprorincialis Lamarck) wurde untersucht. Der Bleigehalt wurde in der Asche des Muschelfleisches durch eine voltammetrische Methode sowie in (> 0.8 m Partikeln) aus Seewasser durch Atomabsorptionsspektroskopie bestimmt. Der Bleigehalt der Miesmuscheln korreliert mit dem Bleigehalt des Seewassers, wobei der Anreicherungsfaktor ungefähr 2300 beträgt.

---

---

Research performed with the financial support of the Consiglio Nazionale delle Ricerche (Roma), Contract n. 77.00009.10-115.38.04.