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Performance and workload modeling has numerous uses at every stage of the high-end computing lifecycle: design, integration, procurement, installation and tuning. Despite the tremendous usefulness of performance models, their construction remains largely a manual, complex, and time-consuming exercise. We propose a new approach to the model construction, called modeling assertions (MA), which borrows advantages from both the empirical and analytical modeling techniques. This strategy has many advantages over traditional methods: incremental construction of realistic performance models, straightforward model validation against empirical data, and intuitive error bounding on individual model terms. We demonstrate this new technique on the NAS parallel CG and SP benchmarks by constructing high fidelity models for the floating-point operation cost, memory requirements, and MPI message volume. These models are driven by a small number of key input parameters thereby allowing efficient design space exploration of future problem sizes and architectures. IntroductionPerformance and workload modeling has numerous uses at every stage of the high-end computing lifecycle: design, integration, procurement, installation, tuning, and maintenance. Despite the tremendous usefulness of performance models, their construction remains largely a manual, complex, and time-consuming exercise. In most cases, researchers create models by manually interrogating applications with an array of performance, debugging, and static analysis tools to refine the model iteratively until the predictions fall within expectations. In other cases, researchers start with an algorithm description, and develop the performance model directly from this abstract description.In this paper, we describe a new approach to performance model construction, called modeling assertions (MA), which borrows advantages from both the empirical and analytical modeling techniques. This strategy has many advantages over traditional methods: isomorphism with the application structure, easy incremental validation of the model with empirical data, uncomplicated sensitivity analysis, and straightforward error bounding on individual model terms. We demonstrate the use of MA by designing a prototype framework, which allows construction, validation, and analysis of models of parallel applications written in FORTRAN and C with the MPI communication library. We use the prototype to construct models of NAS CG and SP benchmarks [4].MA generates two types of representations of the target application: control flow models and symbolic models that can be evaluated with MATLAB or Octave. Symbolic models are generated for the number of floating-point and memory operations, and for MPI point-to-point and collective communication operations. Control flow models provide a mechanism not only to understand the control flow of an application but also to generate alternate model representations in programming languages like C or Python. The models are represented in terms of an application's input pa...

This paper presents a novel VLSI implementation of a MIMO detector for OFDM systems. The proposed architecture is able to perform both linear MMSE and reduced latticeaided MIMO detection, making it possible to adjust the balance between performance and power consumption. In order to facilitate real-time detection in reduced lattice mode of operation, a novel fixed-complexity version of the LLL lattice reduction algorithm has been developed, allowing for strict practical timing requirements, such as those specified for new generation IEEE 802.11n wireless LAN systems, to be met. An implementation of the MIMO detector for a system employing up to 4 transmit and receive antennas is described and its complexity and performance are evaluated.

Beta-thalassaemia is inherited as an autosomal recessive trait in most families. Particular interest has recently been focused on the molecular pathology of the rare forms with a dominant mode of inheritance. The index patient and her mother, who are described in this report, displayed typical clinical and haematological features of beta-thalassaemia intermedia with significant ineffective erythropoiesis and additional peripheral haemolysis. Molecular analysis demonstrated a heterozygous genotype for a novel 6 bp (TGGTCT) deletion of the beta-globin gene involving codons 33-35. This deletion results in the removal of two valine residues from the beta-globin chain at position 33/34 (B15/B16) and the substitution of the tyrosine residue at position 35 (C1) by an aspartic acid (beta 33-35 [B15-C1] Val-Val-Tyr-->0-0-Asp). According to the index patient's place of birth, this abnormal haemoglobin has been termed Hb Dresden. The stability of the variant and the normal beta-globin chains were similar during the incubation period of in vitro globin chain synthesis analysis. However, Hb Dresden is exquisitely unstable and cannot be detected in the peripheral blood by haemoglobin electrophoresis, high-performance liquid chromatography (HPLC) or isoelectric focusing. This instability can be explained by the vital structural role of the three affected amino acids that, in normal haemoglobin, establish a total of nine intermolecular bonds (five hydrophobic and four polar) at both the alpha1beta1 (alpha2beta2) and the alpha1beta2 (alpha2beta1) interface.