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Publicações

2008

Towards Typed Prolog

Autores
Schrijvers, T; Costa, VS; Wielemaker, J; Demoen, B;

Publicação
LOGIC PROGRAMMING, PROCEEDINGS

Abstract
Prolog is traditionally not statically typed. Since the benefits of static typing are huge it was decided to grow a. portable type system inside two widely used open source Prolog systems: SWI-Prolog and Yap. This requires close cooperation and agreement, between the two systems. The type system is Hindley-Milner. The main characteristics of the introduction of types in SWI and Yap are that, typing is not mandatory, that typed and untyped code call be mixed, and that the type checker call insert dynamic type checks at the boundaries between typed and untyped code. The basic decisions and the current status of Hie Typed Prolog project are described. as well as the remaining tasks and problems to be solved.

2008

Survival of gastric and enterohepatic Helicobacter spp. in water: Implications for transmission

Autores
Azevedo, NF; Almeida, C; Fernandes, I; Cerqueira, L; Dias, S; Keevil, CW; Vieira, MJ;

Publicação
APPLIED AND ENVIRONMENTAL MICROBIOLOGY

Abstract
Part of the reason for rejecting aquatic environments as possible vectors for the transmission of Helicobacter pylori has been the preference of this microorganism to inhabit the human stomach and hence use a direct oral-oral route for transmission. On the other hand, most enteric bacterial pathogens are well known for being able to use water as an environmental reservoir. In this work, we have exposed 13 strains of seven different Helicobacter spp. (both gastric and enterohepatic) to water and tracked their survival by standard plating methods and membrane integrity assessment. The influence of different plating media and temperatures and the presence of light on recovery was also assessed. There was good correlation between cultivability and membrane integrity results (Pearson's correlation coefficient = 0.916), confirming that the culture method could reliably estimate differences in survival among different Helicobacter spp. The species that survived the longest in water was H. pylori (> 96 It in the dark at 25 degrees C), whereas H. felis appeared to be the most sensitive to water (<6 h). A hierarchical cluster analysis demonstrated that there was no relationship between the enterohepatic nature of Helicobacter spp. and an increased time of survival in water. This work assesses for the first time the survival of multiple Helicobacter spp., such has H. mustelae, H. muridarum, H. felis, H. canadensis, H. pullorum, and H. canis, in water under several conditions and concludes that the roles of water in transmission between hosts are likely to be similar for all these species, whether enterohepatic or not.

2008

The MARES AUV, a Modular Autonomous Robot for Environment Sampling

Autores
Cruz, NA; Matos, AC;

Publicação
OCEANS 2008, VOLS 1-4

Abstract
In this paper, we discuss the design aspects and the development of the MARES AUV, a 1.5m long vehicle, weighting 32kg, designed and built at the University of Porto, Portugal. This vehicle is highly maneuverable, with the ability to move in the vertical plane, controlling pitch and vertical velocity; forward velocity can also be determined, anywhere between 0 and 2 m/s. MARES can easily integrate any new payload within reason, finding applications in a wide range or areas, such as pollution monitoring, scientific data collection, sonar mapping, underwater video or mine countermeasures.

2008

The Life of a Logic Programming System

Autores
Costa, VS;

Publicação
LOGIC PROGRAMMING, PROCEEDINGS

Abstract
Logic Programming and the Prolog language have a major role in Computing. Prolog, and its derived languages, have been widely used in a impressive variety of application domains. Thus, a bit of the history of Logic Programming reflects in the history of systems such as Dec-10 Prolog [32], M-Prolog [15], C-Prolog [19], Quintus Prolog [20], SICStus Prolog [6], BIM-Prolog [17], ECLiPSe [1], BinProlog [30], SWI-Prolog [34], CIAO [14], and B-Prolog [35], to mention but a few. I briefly present the evolution of one such system, YAP, and present a personal perspective on the challenges ahead for YAP (and for Logic Programming). © 2008 Springer Berlin Heidelberg.

2008

Schema matching on streams with accuracy guarantees

Autores
Gama, J; Aguilar Ruiz, J; Klinkenberg, R;

Publicação
Intelligent Data Analysis

Abstract
We address the problem of matching imperfectly documented schemas of data streams and large databases. Instance-level schema matching algorithms identify likely correspondences between attributes by quantifying the similarity of their corresponding values. However, exact calculation of these similarities requires processing of all database records - which is infeasible for data streams. We devise a fast matching algorithm that uses only a small sample of records, and is yet guaranteed to find a matching that is a close approximation of the matching that would be obtained if the entire stream were processed. The method can be applied to any given (combination of) similarity metrics that can be estimated from a sample with bounded error; we apply the algorithm to several metrics. We give a rigorous proof of the method's correctness and report on experiments using large databases.

2008

Fibre Fabry-Perot sensor for acoustic detection

Autores
Lima, SEU; Frazao, O; Araujo, FM; Ferreira, LA; Miranda, V; Santos, JL;

Publicação
19TH INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS, PTS 1 AND 2

Abstract
Incipient fault diagnosis is closely related to isolation condition assessment. There are a great number of methods available for condition monitoring and diagnosis of power transformer isolation systems, but only few of them can take direct measurements inside the transformer. Fibre optic sensors can be applied to incipient fault diagnosis. In special, acoustic sensors are being developed for the detection and location of partial discharges in oil-filled power transformers. Towards such objective, this work reports investigation on the applicability of fibre Fabry-Perot interferometers for acoustic detection both in air and in liquids.

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