Application-Specific Instruction Set Processor for SoC implementation of Modern Signal Processing Algorithms

A novel application-specific instruction set processor (ASIP) for use in the construction of modern signal processing systems is presented. This is a flexible device that can be used in the construction of array processor systems for the real-time implementation of functions such as singular-value decomposition (SVD) and QR decomposition (QRD), as well as other important matrix computations. It uses a coordinate rotation digital computer (CORDIC) module to perform arithmetic operations and several approaches are adopted to achieve high performance including pipelining of the micro-rotations, the use of parallel instructions and a dual-bus architecture. In addition, a novel method for scale factor correction is presented which only needs to be applied once at the end of the computation. This also reduces computation time and enhances performance. Methods are described which allow this processor to be used in reduced dimension (i.e., folded) array processor structures that allow tradeoffs between hardware and performance. The net result is a flexible matrix computational processing element (PE) whose functionality can be changed under program control for use in a wider range of scenarios than previous work. Details are presented of the results of a design study, which considers the application of this decomposition PE architecture in a combined SVD/QRD system and demonstrates that a combination of high performance and efficient silicon implementation are achievable. © 2005 IEEE.

CORDIC based application-specific instruction set processor for QRD/SVD

An application specific programmable processor (ASIP) suitable for the real-time implementation of matrix computations such as Singular Value and QR Decomposition is presented. The processor incorporates facilities for the issue of parallel instructions and a dual-bus architecture that are designed to achieve high performance. Internally, it uses a CORDIC module to perform arithmetic operations, with pipelining of the internal recursive loop exploited to multiplex the two independent micro-rotations onto a single piece of hardware. The net result is a flexible processing element whose functionality can be changed under program control, which combines high performance with efficient silicon implementation. This is illustrated through the results of a detailed silicon design study and the applications of the techniques to a combined SVD/QRD system.

Evaluation of predicted network modules in yeast metabolism using NMR-based metabolite profiling

Genome-scale metabolic models promise important insights into cell function. However, the definition of pathways and functional network modules within these models, and in the biochemical literature in general, is often based on intuitive reasoning. Although mathematical methods have been proposed to identify modules, which are defined as groups of reactions with correlated fluxes, there is a need for experimental verification. We show here that multivariate statistical analysis of the NMR-derived intra- and extracellular metabolite profiles of single-gene deletion mutants in specific metabolic pathways in the yeast Saccharomyces cerevisiae identified outliers whose profiles were markedly different from those of the other mutants in their respective pathways. Application of flux coupling analysis to a metabolic model of this yeast showed that the deleted gene in an outlying mutant encoded an enzyme that was not part of the same functional network module as the other enzymes in the pathway. We suggest that metabolomic methods such as this, which do not require any knowledge of how a gene deletion might perturb the metabolic network, provide an empirical method for validating and ultimately refining the predicted network structure.

On the Diversity-Multiplexing Tradefoff for Wireless Cooperative Multiple Access Systems

A spectrally efficient strategy is proposed for cooperative multiple access (CMA) channels in a centralized communication environment with $N$ users. By applying superposition coding, each user will transmit a mixture containing its own information as well as the other users', which means that each user shares parts of its power with the others. The use of superposition coding in cooperative networks was first proposed in , which will be generalized to a multiple-user scenario in this paper. Since the proposed CMA system can be seen as a precoded point-to-point multiple-antenna system, its performance can be best evaluated using the diversity-multiplexing tradeoff. By carefully categorizing the outage events, the diversity-multiplexing tradeoff can be obtained, which shows that the proposed cooperative strategy can achieve larger diversity/multiplexing gain than the compared transmission schemes at any diversity/multiplexing gain. Furthermore, it is demonstrated that the proposed strategy can achieve optimal tradeoff for multiplexing gains $0leq r leq 1$ whereas the compared cooperative scheme is only optimal for $0leq r leq ({1}/{N})$. As discussed in the paper, such superiority of the proposed CMA system is due to the fact that the relaying transmission does not consume extra channel use and, hence, the deteriorating effect of cooperative communication on the data rate is effectively limited.

HOS-Based Semi-Blind Spatial Equalization for MIMO Rayleigh Fading Channels

In this paper we concentrate on the direct semi-blind spatial equalizer design for MIMO systems with Rayleigh fading channels. Our aim is to develop an algorithm which can outperform the classical training based method with the same training information used, and avoid the problems of low convergence speed and local minima due to pure blind methods. A general semi-blind cost function is first constructed which incorporates both the training information from the known data and some kind of higher order statistics (HOS) from the unknown sequence. Then, based on the developed cost function, we propose two semi-blind iterative and adaptive algorithms to find the desired spatial equalizer. To further improve the performance and convergence speed of the proposed adaptive method, we propose a technique to find the optimal choice of step size. Simulation results demonstrate the performance of the proposed algorithms and comparable schemes.

Design Methodology for Real-Time FPGA-Based Sound Synthesis

Explicit finite difference (FD) schemes can realise highly realistic physical models of musical instruments but are computationally complex. A design methodology is presented for the creation of FPGA-based micro-architectures for FD schemes which can be applied to a range of applications with varying computational requirements, excitation and output patterns and boundary conditions. It has been applied to membrane and plate-based sound producing models, resulting in faster than real-time performance on a Xilinx XC2VP50 device which is 10 to 35 times faster than general purpose and DSP processors. The models have developed in such a way to allow a wide range of interaction (by a musician) thereby leading to the possibility of creating a highly realistic digital musical instrument.

Structural and functional basis for ADP-ribose and poly(ADP-ribose) binding by viral macro domains.

Macro domains constitute a protein module family found associated with specific histones and proteins involved in chromatin metabolism. In addition, a small number of animal RNA viruses, such as corona- and toroviruses, alphaviruses, and hepatitis E virus, encode macro domains for which, however, structural and functional information is extremely limited. Here, we characterized the macro domains from hepatitis E virus, Semliki Forest virus, and severe acute respiratory syndrome coronavirus (SARS-CoV). The crystal structure of the SARS-CoV macro domain was determined at 1.8-Å resolution in complex with ADP-ribose. Information derived from structural, mutational, and sequence analyses suggests a close phylogenetic and, most probably, functional relationship between viral and cellular macro domain homologs. The data revealed that viral macro domains have relatively poor ADP-ribose 1"-phosphohydrolase activities (which were previously proposed to be their biologically relevant function) but bind efficiently free and poly(ADP-ribose) polymerase 1-bound poly(ADP-ribose) in vitro. Collectively, these results suggest to further evaluate the role of viral macro domains in host response to viral infection.

Application of a Generic Curriculum Change Management Process to Motivate and Excite Students

The School of Mechanical and Aerospace Engineering at Queen’s University Belfast is committed to enhancing the quality of student learning. A plan to implement curriculum change around this goal has been formulated and is already several years underway. A specific part of the plan involved instigating a first year introductory module to engage the students in the practice of their engineering discipline. The complicated nature of devising this type of module with regard to objectives, resources, timeframe and the number of students involved meant that a very systematic approach had to be adopted. This paper presents the simple but definitive change management process that facilitated in the creation of a first year Introduction to Engineering module. The generic nature of this process is described and its application to other facets of curriculum change is discussed. Within this process the importance of collaboration to establish a forward momentum is emphasised. This enables academic staff to progress as a group and build curriculum development based on their own experiences, expertise and established practice

On the Sphere Decoder for Frequency-Selective MIMO channels

This paper compares the complexity of the sphere decoder (SD) and a previously proposed detection scheme, denoted here as block SD (BSD), when they are applied to the detection of multiple-input multiple-output (MIMO) systems in frequency-selective channels. The complexity of both algorithms depends on their preprocessing and tree search stages. Although the BSD was proposed as a means of greatly reducing the complexity of the preprocessing stage of the SD, no study was done on how the complexity of the tree search stage could be affected by that reduced preprocessing stage. This paper shows, both analytically and through simulation, that the reduction in preprocessing complexity provided by the BSD has the side effect of increasing the complexity of its tree search stage compared to that of the SD, independent of the signal-to-noise ratio (SNR). In addition, this paper shows how sorting the columns of the frequency-selective channel matrix in the SD does not reduce the complexity of the tree search stage, contrary to what occurs in frequency-flat channels.

Improved Linear Transmit Processing for Single-User and Multi-User MIMO Communications Systems

In this paper, we propose a novel linear transmit precoding strategy for multiple-input, multiple-output (MIMO) systems employing improper signal constellations. In particular, improved zero-forcing (ZF) and minimum mean square error (MMSE) precoders are derived based on modified cost functions, and are shown to achieve a superior performance without loss of spectrum efficiency compared to the conventional linear and nonlinear precoders. The superiority of the proposed precoders over the conventional solutions are verified by both simulation and analytical results. The novel approach to precoding design is also applied to the case of an imperfect channel estimate with a known error covariance as well as to the multi-user scenario where precoding based on the nullspace of channel transmission matrix is employed to decouple multi-user channels. In both cases, the improved precoding schemes yield significant performance gain compared to the conventional counterparts.

Loss of the LAT adaptor converts antigen-responsive T cells into pathogenic effectors that function independently of the T cell receptor.

Despite compromised T cell antigen receptor (TCR) signaling, mice in which tyrosine 136 of the adaptor linker for activation of T cells (LAT) was constitutively mutated (Lat(Y136F) mice) accumulate CD4(+) T cells that trigger autoimmunity and inflammation. Here we show that equipping postthymic CD4(+) T cells with LATY136F molecules or rendering them deficient in LAT molecules triggers a lymphoproliferative disorder dependent on prior TCR engagement. Therefore, such disorders required neither faulty thymic T cell maturation nor LATY136F molecules. Unexpectedly, in CD4(+) T cells recently deprived of LAT, the proximal triggering module of the TCR induced a spectrum of protein tyrosine phosphorylation that largely overlapped the one observed in the presence of LAT. The fact that such LAT-independent signals result in lymphoproliferative disorders with excessive cytokine production demonstrates that LAT constitutes a key negative regulator of the triggering module and of the LAT-independent branches of the TCR signaling cassette.

Wholeness of healing: an innovative Student-Selected Component introducing United Kingdom medical students to the spiritual dimension in healthcare.

Objective: This Student Selected Component (SSC) was designed to equip United Kingdom (UK) medical students to engage in whole-person care. The aim was to explore students' reactions to experiences provided, and consider potential benefits for future clinical practice.

Methods: The SSC was delivered in the workplace. Active learning was encouraged through facilitated discussion with and observation of clinicians, the palliative team, counselling services, hospital chaplaincy and healing ministries; sharing of medical histories by patients; and training in therapeutic communication. Assessment involved reflective journals, literature appraisal, and role-play simulation of the doctor-patient consultation. Module impact was evaluated by analysis of student coursework and a questionnaire.

Results: Students agreed that the content was stimulating, relevant, and enjoyable and that learning outcomes were achieved. They reported greater awareness of the benefit of clinicians engaging in care of the "whole person" rather than "the disease." Contributions of other professions to the healing process were acknowledged, and students felt better equipped for discussion of spiritual issues with patients. Many identified examples of activities which could be incorporated into core teaching to benefit all medical students.

Conclusion: The SSC provided relevant active learning opportunities for medical students to receive training in a whole-person approach to patient care.