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[France] Conception of a parametric model for voice quality assessment in a mixed context (Narrow Band and Wide Band) intended for implementation at a

Voice quality constitutes the key element of the customer’s feeling and trust towards his telecom operator. Consequently, it is essential that France Telecom possesses means of voice quality assessment as it is a vital aspect for VoIP service provision. Quality should be supervised at the end-point where it presents the most faithful reflection of customer’s perception. However, most of the existing methods seem inadequate for this use. Even though the signal-based measuring methods evaluate well end-to-end quality

Voice quality constitutes the key element of the customer’s feeling and trust towards his telecom operator. Consequently, it is essential that France Telecom possesses means of voice quality assessment as it is a vital aspect for VoIP service provision. Quality should be supervised at the end-point where it presents the most faithful reflection of customer’s perception. However, most of the existing methods seem inadequate for this use. Even though the signal-based measuring methods evaluate well end-to-end quality, their implementation in customer gateways is impossible, mainly because of lack of resources. For the purpose of supervision it is recommended to use parametrical models, such as the E model (ITU-T G.107) or models compliant with ITU-T P.564, which do not require neither complex signal processing nor a reference signal. For practical reasons, France Telecom chose to work on the E-model instead of developing a totally new model.

Nevertheless, our experience regarding the use of the E model in end-point voice quality assessing probes has demonstrated some substantial drawbacks of the model. According to several published tests, the model judges too severely the degradations due to packet loss, jitter and delay, and therefore underpredicts quality. On the other hand, the information about packet loss, jitter and delay is often the only available in an end-point. Therefore, in the first place it is important to construct a new model which will evaluate better the influence of these three factors on quality. However, if time allows we do not exclude the possibility of including other parameters, such as noise or echo.

The most important part of the study will concern the study of the influence of packet loss on voice quality for the purposes of real-time measurement. The impact of certain parameters such as delay or noise has already been studied by France Telecom and elsewhere. It is only required to integrate them into one unique quality evaluation model. We would also like, that the model took into account dynamic phenomena such as recency effect. At the end, the model should evaluate quality score in narrow band (300-3400 Hz) as well as wide band (50-7000 Hz) on a single, mixed, quality scale.

In order to construct the model the creation of new subjective databases will be necessary. Some work can be based on objective tests (PESQ), using the test chain which has been developed in our team.

A validation of the performance of the model (formally at the end of the development, but also probably on intermediate versions) is necessary. In particular, the use of the method described in ITU-T P.564 will be deeply appreciated.

Applicant profile (not all are required)
C and Matlab programming
Data analysis, statistical methods
Mathematics
Understanding of human perception and judgment, especially of psychophysics
QoS, voice quality
VoIP comprehension (in particular of voice flows: protocols, codecs, jitter buffer, aspects related to packet loss, jitter and delay)
IP comprehension
Experience in neural networks is considered as an optional plus

contact
Please send applications to:
Anna CZUCZMAN
France Telecom – Division R&D
TECH/SSTP – Lannion
anna.czuczman [a-t] orange-ftgroup.com
(+33) 2 96 05 22 90


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PhD in Decision Neuroscience - Trinity College Dublin

Research Assistant position in Decision Neuroscience
O’Doherty lab, Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland.

A post-graduate research assistant position is available in the laboratory of Prof. John P. O’Doherty at Trinity College Dublin. The position, part of a research programme funded by Science Foundation Ireland, will involve contributing to the organization of a research programme concerned with uncovering the neural mechanisms underlying choice, reward-learning and decision making in the brain. Duties include helping with subject recruitment, running experiments (brain imaging and behavioural studies) and contributing to data analysis.

An undergraduate degree in psychology, neuroscience, computer science, mathematics or a related discipline would be a pre-requisite, and evidence of strong quantitative skills in computer programming, mathematics and statistics would be essential. Some prior exposure to cognitive, behavioural or computational neuroscience would be an advantage. The project will be carried out using state of the art MRI facilities at the Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland. The position is available for a period of 2 to 3 years.

Start date: As soon as is practicable.

Interested candidates should send a CV, brief statement of research interests, and contact details for two referees to John O’Doherty: odoherjp at tcd.ie. Informal enquiries are also welcome.

Applications will be accepted until the position is filled.
Trinity College Dublin is an equal opportunity employer.


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Postdoctoral and PhD Student Positions in Neurochoice, the University of Zurich

Postdoctoral and PhD Student Positions in Neurochoice, the University of Zurich, Switzerland

SystemsX.ch, the Swiss initiative in systems biology, has initiated a new project entitled “Neurochoice: Neural Correlates of Collective Decision Making”, with principal investigators located at the Universi-ties of Zurich, Bern, and Geneva, and the Swiss Federal Institute of Technology in Lausanne. One part of the project, focusing on fMRI studies of the role of risk during human decision-making, will be completed under the direction of Prof. Ernst Fehr and Kerstin Preuschoff at the Institute for Empirical Research in Economics in Zurich. We are presently seeking applicants for the positions of post-doctoral researcher and PhD student.

These positions require a background in neurobiology, economics, psychology or computer science, and an interest in neuroeconomics and/or mathematical modeling of behavioral and neuroimaging data. Previous experience in neuroimaging techniques and fMRI data analysis is a major advantage. Candidates should have an interest in designing and conducting experiments in neuroeconomics and social neuroscience. Finally, candidates should have programming experience, e.g. in MATLAB or similar languages.

Employment can begin immediately but is negotiable. The Institute for Empirical Research in Economics offers an exciting and interdisciplinary work environment and excellent research facilities, including a 3T MRI scanner dedicated to research and a large and well-equipped laboratory for conducting behavioral experiments.

Application may be made electronically or by post. Please submit your CV, copies of all relevant diplomas, a statement of interest, and the names and email addresses of two referees to the following address by December 14, 2008: Sally Gschwend, Institute for Empirical Research in Economics, Blümlisalpstr. 10, 8006 Zürich , Switzerland, s.gschwend[ at ]iew.uzh.ch

The University of Zurich is an equal opportunity employer, and as such welcomes applications from women and minority candidates.


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Postgraduate Studentship on Modelling Coronary Blood Flow Dynamics - University of Oxford

Postgraduate Studentship
Modelling Coronary Blood Flow Dynamics
Department of Mathematics

STUDENTSHIP covers fees (University and College) and maintenance.

Applications are invited for a postgraduate studentship, funded by the King Abdullah University of Science and Technology Global Research Partnership [KAUST GRP], to work on “Modelling Coronary Blood Flow Dynamics” under the supervision of Dr Nic Smith and Prof. Jon Chapman. This DPhil studentship will start on 1 October 2009, is available to all nationalities, covers maintenance and full overseas fees and will be based in the newly established Oxford Centre for Collaborative Applied Mathematics (OCCAM).

OCCAM has been established with substantial funding from the KAUST GRP. The Centre, which is part of the Mathematical Institute, will be allied to a global network of mathematicians. Aiming to meet the ever-increasing global demand for quantitative understanding of complex scientific phenomena, OCCAM has been built on the strength of four pre-existing groups of applied and computational mathematicians working in Oxford: the Oxford Centre for Industrial and Applied Mathematics, the Centre for Mathematical Biology, the Numerical Analysis Group and the Computational Biology Group. It has a symbiotic relationship with other scientific communities which have a need for problem-solving mathematics both within the University of Oxford and beyond. Over the first five years the centre will employ 40 new staff and students.

Coronary heart disease remains the leading cause of death in the western world. Recent advances in high performance computing and medical imaging have lead to the development of detailed models of vascular structure and blood flow respectively. These techniques now enable the simulation of perfusion through three dimensional representations of vascular geometry. However, there are two difficulties with these classes of models: (1) the computational simulation of flow through complete vascular beds from feeding vessels to capillaries is computationally prohibitive and (2) it is impossible to measure flow in all vessels and thus fully validate such models for clinical application. Recent developments in Perfusion MRI and Nuclear Medicine by our clinical collaborators at St Thomas’ Hospital now provide the ability to accurately measure blood volume in cardiac tissue. This presents an opportunity to develop a novel modelling framework to explicitly address these limitations by linking vascular structure to whole organ perfusion through the application of a multi-scale porous-flow model.

The goal of this project will be to develop models with the potential to directly interpret clinically acquired perfusion images and guide revascularisation strategies in the heart. The methodology will be based on homogenizing discrete vascular structures by applying previously developed asymptotic approach. A key mathematical challenge will be adapting the multiple scales technique to the hierarchical branching structure of blood vessels. This may lead to a continuum sub-model for each generation of vessel (e.g. capillaries, arterioles, small/large coronary vessels) which are coupled to produce a full multi-domain and multi-scale representational of coronary perfusion. These predicted perfusion fields will be mathematically validated via comparison with the perfusion fields determined using the discrete model whose structure was used to define the porosity tensor. Finally the model will be applied to human data collected at St Thomas’ to assess the clinical potential of the approach.

The collaborators on this project are Professor Jos Spaan (Department Medical Physics, University of Amsterdam) and Professor Eike Nagel (Guy’s and St Thomas’ Hospital).

The studentship is attached to St Anne’s College.
For information about OCCAM please visit the official website: www.maths.ox.ac.uk/occam

Applications can be made online at www.ox.ac.uk/admissions/postgraduate_courses/apply/how_to_apply.html and should include a CV, covering letter, three references and a transcript of your undergraduate degree. Alternatively, applications can be sent to Margret Sloper at the Mathematical Institute using the University’s application form for graduate study, which can be downloaded from the above link. Applications must arrive by end of day Friday 27th February 2009. The reference for this application is BK/08/058; make sure that you state this in the covering letter. Applicants must arrange for their referees to send references directly to the Graduate Studies Assistant (fax or e-mail is sufficient) by the closing date. For further details about the projects, including the application process, please see the Further Particulars link below, or contact Graduate Studies, email graduate.studies [ -a-t- ] maths.ox.ac.uk. Oxford University is an Equal Opportunity Employer.


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