Vc: A C++ library for explicit vectorization

It is an established trend that CPU development takes advantage of Moore's Law to improve in parallelism much more than in scalar execution speed. This results in higher hardware thread counts (MIMD) and improved vector units (SIMD), of which the MIMD developments have received the focus of library research and development in recent years. To make use of the latest hardware improvements, SIMD must receive a stronger focus of API research and development because the computational power can no longer be neglected and often auto‐vectorizing compilers cannot generate the necessary SIMD code, as will be shown in this paper. Nowadays, the SIMD capabilities are sufficiently significant to warrant vectorization of algorithms requiring more conditional execution than was originally expected for Streaming SIMD Extension to handle. The Vc library ( http://compeng.uni‐frankfurt.de/?vc ) was designed to support developers in the creation of portable vectorized code. Its capabilities and performance have been thoroughly tested. Vc provides portability of the source code, allowing full utilization of the hardware's SIMD capabilities, without introducing any overhead. Copyright © 2011 John Wiley & Sons, Ltd.     

Dijkstra, Floyd and Warshall meet Kleene

Around 1960, Dijkstra, Floyd and Warshall published papers on algorithms for solving single-source and all-sources shortest path problems, respectively. These algorithms, nowadays named after their inventors, are well known and well established. This paper sheds an algebraic light on these algorithms. We combine the shortest path problems with Kleene algebra, also known as Conway’s regular algebra. This view yields a purely algebraic version of Dijkstra’s shortest path algorithm and the one by Floyd/Warshall. Moreover, the algebraic abstraction yields applications of these algorithms to structures different from graphs and pinpoints the mathematical requirements on the underlying cost algebra that ensure their correctness.     

Physical attractiveness and health: Comment on Weeden and Sabini (2005).

Evolutionary behavioral biology suggests that certain characteristics of the human face and body are important for mate preferences and are therefore subject to sexual selection. J. Weeden and J. Sabini (see record 2005-11504-001) identify a number of weaknesses in the association between traits' attractiveness and health. In contrast, the authors argue that (a) studies on preferences for physical characteristics that rely on 1 trait permit only limited interpretation, (b) limitations placed on J. Weeden and J. Sabini's review exclude important associations, (c) there are misconceptions in their treatment of some traits, and (d) their selected literature provides an inaccurate picture regarding effect size. The authors suggest that future research in this field should seek conceptual and methodological constancy in trait selection and in the evaluation of attractiveness- and health-related traits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

XML strategies for legacy database search

Over the past few years, XML (Extensible Markup Language) has become the standard for data and document interchange between distributed systems. With the continuing proliferation of the Internet, XML has also become a key technology for transactional e-business. A large percentage of Internet interactions, however, involves searching through documents, Web pages, databases, and other information resources. This article explores some of the ways XML can improve these types of searches. It focuses particularly on searches through legacy databases and on the changes you can make to your legacy systems to effectively exploit XML.     

Extracting Interpretable Fuzzy Rules from RBF Networks

Radial basis function networks and fuzzy rule systems are functionally equivalent under some mild conditions. Therefore, the learning algorithms developed in the field of artificial neural networks can be used to adapt the parameters of fuzzy systems. Unfortunately, after the neural network learning, the structure of the original fuzzy system is changed and interpretability, which is considered to be one of the most important features of fuzzy systems, is usually impaired. This Letter discusses the differences between RBF networks and interpretable fuzzy systems. Based on these discussions, a method for extracting interpretable fuzzy rules from RBF networks is suggested. Simulation examples are given to embody the idea of this paper.     

Mutation Testing in the Refinement Calculus

This article discusses mutation testing strategies in the context of refinement. Here, a novel generalisation of mutation testing techniques is presented to be applied to contracts ranging from formal specifications to programs. It is demonstrated that refinement and its dual abstraction are the key notions leading to a precise and yet simple theory of mutation testing. The refinement calculus of Back and von Wright is used to express concepts like contracts, useful mutations, test cases and test coverage.     

Numerical integration of singular integrands using low-discrepancy sequences

We investigate quasi-Monte Carlo integration for functions on thes-dimensional unit cube having point singularities. Error bounds are proved and the theoretical results are verified by computations using Halton, Sobol’ and Niederreiter sequences. Supported by the Austrian Science Foundation (Project 10223-PHY).     

GPS-based Clock Synchronization in a Mobile,Distributed Real-Time System

In a vehicle tracking system computers aboard moving vehicles determine periodically their geographical position and transmit it to a control center. This paper presents a commercial vehicle tracking system as an example of a distributed real-time system with mobile components and focuses on the issue of clock synchronization. The mobile components of the system obtain highly accurate timing information from the Global Positioning System which is used to synchronize their local clocks to UTC world time. Thus a tight clock synchronization is achieved without imposing additional load on the communication channels of the system.     

Das Problem der verantworteten Therapieentscheidung in der Neonatologie

Definition of the problem: Physicians and nurses who work in neonatology—as in intensive care at all—are often forced to decide whether to stop or to continue with the treatment of a severely ill patient. The literature provides several decision making instruments, which are meant to help and to rationalize such decisions. Method and conclusion: Two of these instruments (“Schema zur ethischen Urteilsbildung nach dem Muster der aristotelischen Ethik”, Honnefelder 1994; “Nimwegener Methode für ethische Fallbesprechung”, Gordijn 1998) were tested by retrospectively examining two cases of our NICU. Results of our study show that the use of a decision making instrument is basically helpful. But the above mentioned instruments showed also shortcomings when used in the framework of neonatology. Therefore we developed the “Kölner Arbeitsbogen zur ethischen Entscheidungsfindung in der Neonatologie”, which is adapted to the specific needs of neonatology.     

Towards Pseudonymous e-Commerce

The lack of privacy is one of the main reasons that limits trust in e-commerce. Current e-commerce practice enforces a customer to disclose her identity to the e-shop and the use of credit cards makes it straightforward for an e-shop to know the real identity of its customers. Although there are some payment systems based on untraceable tokens, they are not as widely used as credit cards. Furthermore, even without buying anything, a customer is already disclosing some information about who or where she may be by just connecting to the e-shop's web server and leaving behind an IP-address. In this paper, we present novel components that enable secure pseudonymous e-commerce. On the one hand, these components allow a customer to browse through an e-shop, select goods, and pay the goods with her credit card such that neither the e-shop operator nor the credit card issuer nor an eavesdropper is able to get any information about the customer's identity. On the other hand, it is guaranteed that none of the involved parties is able to act dishonestly during the credit card payment. Such a system could greatly enhance trust in e-commerce since it overcomes the customers' privacy concerns.