Abstract
Several business applications such as marketing basket analysis, clickstream analysis, fraud detection and churning migration analysis demand gradient data analysis. By employing gradient data analysis one is able to identify trends, outliers and answering "what-if' questions over large databases. Gradient queries were first introduced by Imielinski et al [1] as the cubegrade problem. The main idea is to detect interesting changes in a multidimensional space (MDS). Thus, changes in a set of measures (aggregates) are associated with changes in sector characteristics (dimensions). MDS contains a huge number of cells which poses great challenge for mining gradient cells on a useful time. Dong et al [2] have proposed gradient constraints to smooth the computational costs involved in such queries. Even by using such constraints on large databases, the number of interesting cases to evaluate is still large. In this work, we are interested to explore best cases (Top-K cells) of interesting multidimensional gradients. There several studies on Top-K queries, but preference queries with multidimensional selection were introduced quite recently by Dong et al [9]. Furthermore, traditional Top-K methods work well in presence of convex functions (gradients are non-convex ones). We have revisited iceberg cubing for complex measures, since it is the basis for mining gradient cells. We also propose a gradient-based cubing strategy to evaluate interesting gradient regions in MDS. Thus, the main challenge is to find maximum gradient regions (MGRs) that maximize the task of mining Top-K gradient cells. Our performance study indicates that our strategy is effective on finding the most interesting gradients in multidimensional space.

Abstract
In this paper we present the development, implementation and simulation of a simple Distributed Hash Table (DHT) protocol for a Peer to peer (P2P) overlay network inspired by small world [3, 2] concepts. Our simulation and implementation, done on the Peersim [10] java network simulator, showed results consistent with other state of the art DHT implementations with a more simple and pragmatic approach for the graph construction algorithm. We present the results Of Simulating this protocol on large P2P networks and compare them with the results obtained in Symphony [14], another small world inspired DHT.

Abstract
Bread is one of the most consumed staple food by man. However, its high salt level has been while of concern, especially because of the relationship between salt intake and Hipertension development, with high prevalence in Portugal. The purpose of this study was to analyse the sodium content in white bread, the most consumed bread by Portuguese. This study was developed in two different phases, March and May. To quantify the sodium level, flame photometry technique has been used, previously validated for the study. The bread samples were acquired in 80 different bakeries located in 12 different areas of Oporto city. The sodium concentration in bread samples ranged between 344 mg/100g and 718 mg/100g (mean 534 mg/100g, standard deviation 30 mg/100g). There was no significant association between the weight of the bread and its sodium concentration. The principal component decomposition of the studied variables allows the observation of the different characteristics of the evaluated areas of Oporto.

Abstract
Byte stuffing is a technique to allow the transparent transmission of arbitrary sequences with constrained sequences. To date, most of the existing algorithms, such as PPP, attain a low average overhead by sacrificing the worst-case scenario. An exception is COBS which was designed for a low worst-case overhead; however, it imposes always a nonzero overhead, even on small packets. In this work is proposed a byte stuffing algorithm that simultaneously controls the average and worst-case overhead, performing close to the theoretical bound. It is shown analytically that the proposed algorithm achieves improved average and worst-case rates over state of the art methods. Furthermore, this technique is generalized to hybrid methods, with lower computing complexity. It is further analysed and compared experimentally the behaviour of the proposed algorithm against established algorithms in terms of byte overhead and computational time.

Abstract
Hollow-core photonic crystal fibres have a high potential for gas sensing applications, since large light-gas interaction lengths can be effectively attained. Nevertheless, in order to enhance effective diffusion of gas into the fibre hollow-core multi-coupling gaps are needed, which raise coupling loss issues that must be evaluated prior to the development of practical systems. In this communication we present a study on the coupling losses dependence on lateral and axial gap misalignment for single-mode fibre and two different types of hollow-core photonic crystal fibres. In addition, experimental results on the splicing of these fibres are also presented.

Abstract
In this paper we propose to use Interaction Nets as a formalism for Visual Functional Programming. We consider the use of recursion patterns as a programming idiom, and introduce a suitable archetype/instantiation mechanism for interaction agents, which allows one to define agents whose behaviour is based on recursion patterns. © 2007, Universitatsbibliothek TU Berlin.