The impact of resource dependence of the mechanisms of life on the spatial population dynamics of an in silico microbial community

Biodiversity has a critical impact on ecosystem functionality and stability, and thus the current biodiversity crisis has motivated many studies of the mechanisms that sustain biodiversity, a notable example being non-transitive or cyclic competition. We therefore extend existing microscopic models of communities with cyclic competition by incorporating resource dependence in demographic processes, characteristics of natural systems often oversimplified or overlooked by modellers. The spatially explicit nature of our individual-based model of three interacting species results in the formation of stable spatial structures, which have significant effects on community functioning, in agreement with experimental observations of pattern formation in microbial communities. Published by AIP Publishing

A Benchmarking Index to Compare High-performing Computing Systems

An index to compare supercomputers is proposed in the study. This index is based on the concept of technical efficiency and is developed adopting a non-parametric technique, e.g. Data Envelopment Analysis. The index is used to calculate the technical efficiency of 500 high-performing computing systems listed in the TOP500 supercomputers database. Finally, statistical analysis is performed to assess the weight that some supercomputers characteristics have on their efficiency

Steering in computational science: mesoscale modelling and simulation

This paper outlines the benefits of computational steering for high performance computing applications. Lattice-Boltzmann mesoscale fluid simulations of binary and ternary amphiphilic fluids in two and three dimensions are used to illustrate the substantial improvements which computational steering offers in terms of resource efficiency and time to discover new physics. We discuss details of our current steering implementations and describe their future outlook with the advent of computational grids.Comment: 40 pages, 11 figures. Accepted for publication in Contemporary Physic

TECHNOLOGY TRANSFER FROM THE UNIVERSITY OF MINNESOTA ESTIMATING THE ECONOMIC IMPACT

There is strong synergy among research, education, technology development and technology transfer. Examples of successful public-private technology transfer linkage institutions are provided. But efforts to document the benefits of research conducted at the University of Minnesota to the state have rarely been conducted with the rigor that would be required to meet the test of professional credibility. A program of research to develop more rigorous evidence on economic benefits to the State is proposed.Research and Development/Tech Change/Emerging Technologies,

Metascheduling of HPC Jobs in Day-Ahead Electricity Markets

High performance grid computing is a key enabler of large scale collaborative computational science. With the promise of exascale computing, high performance grid systems are expected to incur electricity bills that grow super-linearly over time. In order to achieve cost effectiveness in these systems, it is essential for the scheduling algorithms to exploit electricity price variations, both in space and time, that are prevalent in the dynamic electricity price markets. In this paper, we present a metascheduling algorithm to optimize the placement of jobs in a compute grid which consumes electricity from the day-ahead wholesale market. We formulate the scheduling problem as a Minimum Cost Maximum Flow problem and leverage queue waiting time and electricity price predictions to accurately estimate the cost of job execution at a system. Using trace based simulation with real and synthetic workload traces, and real electricity price data sets, we demonstrate our approach on two currently operational grids, XSEDE and NorduGrid. Our experimental setup collectively constitute more than 433K processors spread across 58 compute systems in 17 geographically distributed locations. Experiments show that our approach simultaneously optimizes the total electricity cost and the average response time of the grid, without being unfair to users of the local batch systems.Comment: Appears in IEEE Transactions on Parallel and Distributed System

Cloud Computing in the Global South: Drivers, Effects and Policy Measures

Cloud computing has started to transform economic activities in the global South. Many businesses are taking advantage of the pay-as-you-go model of the technology, and its scalability and flexibility features, and government agencies in the South have been investing in cloud-related mega-projects. Cloud-based mobile applications are becoming increasingly popular and the pervasiveness of cellphones means that the cloud may transform the way these devices are used. However, findings and conclusions drawn from surveys, studies and experiences of companies on the potential and impact of cloud computing in the developing world are inconsistent. This article reviews cloud diffusion in developing economies and examines some firms in the cloud's supply side in these economies to present a framework for evaluating the attractiveness of this technology in the context of evolving needs, capabilities and competitive positions. It examines how various determinants related to the development and structure of related industries, externality mechanisms and institutional legitimacy affect cloud-related performances and impacts

A Comparison of some recent Task-based Parallel Programming Models

The need for parallel programming models that are simple to use and at the same time efficient for current ant future parallel platforms has led to recent attention to task-based models such as Cilk++, Intel TBB and the task concept in OpenMP version 3.0. The choice of model and implementation can have a major impact on the final performance and in order to understand some of the trade-offs we have made a quantitative study comparing four implementations of OpenMP (gcc, Intel icc, Sun studio and the research compiler Mercurium/nanos mcc), Cilk++ and Wool, a high-performance task-based library developed at SICS. Abstract. We use microbenchmarks to characterize costs for task-creation and stealing and the Barcelona OpenMP Tasks Suite for characterizing application performance. By far Wool and Cilk++ have the lowest overhead in both spawning and stealing tasks. This is reflected in application performance when many tasks with small granularity are spawned where Cilk++ and, in particular, has the highest performance. For coarse granularity applications, the OpenMP implementations have quite similar performance as the more light-weight Cilk++ and Wool except for one application where mcc is superior thanks to a superior task scheduler. Abstract. The OpenMP implemenations are generally not yet ready for use when the task granularity becomes very small. There is no inherent reason for this, so we expect future implementations of OpenMP to focus on this issue