A Constraint-based Approach to Web Services Provisioning

In this paper we consider the provisioning problem of Web services. Our framework is based on the existence of an abstract composition, i.e., the way some services of different types can be combined together in order to achieve a given task. Our approach consists in instantiating this abstract representation of a composite Web service by selecting the most appropriate concrete Web services. This instantiation is based on constraint programming techniques which allows us to match the Web services according to a given request. Our proposal performs this instantiation in a distributed manner, i.e., the solvers for each service type are solving some constraints at one level, and they are forwarding the rest of the request (modified by the local solution) to the next services. When a service cannot provision part of the composition, a distributed backtrack mechanism enables to change previous solutions (i.e., provisions). A major interest of our approach is to preserve privacy: solutions are not sent to the whole composition, services know only the services to which they are connected, and parts of the request that are already solved are removed from the next requests. We introduce a specific data structure, namely Message Treatment Structure, for modeling the problem. We show the interest of this data structure to express the general principles of our framework and the related algorithms

How Efficient is Rotational Mixing in Massive Stars ?

The VLT-Flames Survey for Massive Stars (Evans05,Evans06) provides recise measurements of rotational velocities and nitrogen surface abundances of massive stars in the Magellanic Clouds. Specifically, for the first time, such abundances have been estimated for stars with significant rotational velocities. This extraordinary data set gives us the unique possibility to calibrate rotationally and magnetically induced mixing processes. Therefore, we have computed a grid of stellar evolution models varying in mass, initial rotational velocity and chemical composition. In our models we find that although magnetic fields generated by the Spruit-Taylor dynamo are essential to understand the internal angular momentum transport (and hence the rotational behavior), the corresponding chemical mixing must be neglected to reproduce the observations. Further we show that for low metallicities detailed initial abundances are of prime importance, as solar-scaled abundances may result in significant calibration errors.Comment: To appear in the proceedings of "First Stars III", Santa Fe, New Mexico, July 16-20, 2007, 3 pages, 3 figure

How Efficient is Rotational Mixing in Massive Stars ?

The VLT-Flames Survey for Massive Stars (Evans05,Evans06) provides recise measurements of rotational velocities and nitrogen surface abundances of massive stars in the Magellanic Clouds. Specifically, for the first time, such abundances have been estimated for stars with significant rotational velocities. This extraordinary data set gives us the unique possibility to calibrate rotationally and magnetically induced mixing processes. Therefore, we have computed a grid of stellar evolution models varying in mass, initial rotational velocity and chemical composition. In our models we find that although magnetic fields generated by the Spruit-Taylor dynamo are essential to understand the internal angular momentum transport (and hence the rotational behavior), the corresponding chemical mixing must be neglected to reproduce the observations. Further we show that for low metallicities detailed initial abundances are of prime importance, as solar-scaled abundances may result in significant calibration errors.Comment: To appear in the proceedings of "First Stars III", Santa Fe, New Mexico, July 16-20, 2007, 3 pages, 3 figure

Analyzing Visual Mappings of Traditional and Alternative Music Notation

In this paper, we postulate that combining the domains of information visualization and music studies paves the ground for a more structured analysis of the design space of music notation, enabling the creation of alternative music notations that are tailored to different users and their tasks. Hence, we discuss the instantiation of a design and visualization pipeline for music notation that follows a structured approach, based on the fundamental concepts of information and data visualization. This enables practitioners and researchers of digital humanities and information visualization, alike, to conceptualize, create, and analyze novel music notation methods. Based on the analysis of relevant stakeholders and their usage of music notation as a mean of communication, we identify a set of relevant features typically encoded in different annotations and encodings, as used by interpreters, performers, and readers of music. We analyze the visual mappings of musical dimensions for varying notation methods to highlight gaps and frequent usages of encodings, visual channels, and Gestalt laws. This detailed analysis leads us to the conclusion that such an under-researched area in information visualization holds the potential for fundamental research. This paper discusses possible research opportunities, open challenges, and arguments that can be pursued in the process of analyzing, improving, or rethinking existing music notation systems and techniques.Comment: 5 pages including references, 3rd Workshop on Visualization for the Digital Humanities, Vis4DH, IEEE Vis 201

How to Couple from the Past Using a Read-Once Source of Randomness

We give a new method for generating perfectly random samples from the stationary distribution of a Markov chain. The method is related to coupling from the past (CFTP), but only runs the Markov chain forwards in time, and never restarts it at previous times in the past. The method is also related to an idea known as PASTA (Poisson arrivals see time averages) in the operations research literature. Because the new algorithm can be run using a read-once stream of randomness, we call it read-once CFTP. The memory and time requirements of read-once CFTP are on par with the requirements of the usual form of CFTP, and for a variety of applications the requirements may be noticeably less. Some perfect sampling algorithms for point processes are based on an extension of CFTP known as coupling into and from the past; for completeness, we give a read-once version of coupling into and from the past, but it remains unpractical. For these point process applications, we give an alternative coupling method with which read-once CFTP may be efficiently used.Comment: 28 pages, 2 figure

Listen Imagine Compose - Research Report

Listen, Imagine, Compose (LIC) is a project designed to investigate pedagogies of composing in secondary schools. It was funded by the Esmée Fairbairn foundation, and organised by Sound and Music (SAM), Birmingham Contemporary Music Group (BCMG), with Birmingham City University (BCU) as the lead academic partner. It involved composers, an apprentice composer, musicians, schoolteachers, researchers, music education partners, and critical friends. The main body of the project ran between June 2011 – Spring 2013. Background The 2009 Ofsted report Making More of Music (Ofsted, 2009) highlighted a number of issues with composing in secondary school music provision, including: lack of attention to internalising sound as a basis for creative thinking; lack of quality and depth in pupil responses; insufficient understanding of what musical progress involves; composing activities are rarely related to the work of established composers. We know that composing is the area of the music curriculum that is often least accessible for teachers (Berkley, 2001), and that changes to the Key Stage 3 Curriculum in operation during the research period placed increased stress on genuinely creative thinking. The purpose of the LIC project was to address these issues through interaction between pupils and their teachers with professional composers and performers