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James Walder

Publications and source records attributed to James Walder.

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Improving the Energy Efficiency of High Throughput Computing: A Measurement-Based Case Study

The significant energy consumed by data centers has become a concern both for costs and associated carbon emissions. In particular, the energy efficiency of servers is a key consideration for data center operators, and understanding servers' power consumption under different operating conditions is an important aspect of it. In this paper, we present a measurement-based case study of high-throughput computing. We analyze power usage information of an operational data center, combined with focused measurements of power reduction techniques for a representative high-throughput workload. The study points out the obstacles encountered by data center operators in their efforts to minimize energy consumption and carbon emissions, and discusses the impact of server configuration adjustments on the energy consumption of processing jobs. We offer actionable recommendations for decreasing the energy usage of servers, while considering both performance and carbon emissions.

cs.NI

Studies of CP-conserving and CP-violating Bs mixing parameters with the D0 experiment

This paper summarises the recent results of the Run IIa D0 experiment at the Tevatron Collider at Fermilab on the observable parameters of the $B_{s}$ meson. A measurement of the branching fraction $B_s->D_s^{(*)}D_s^{(*)}$ is reported, which provides an estimate of the width difference $ΔΓ_{s}^{CP}/ΔΓ_{s}$. Through the decay $B_{s} \to J/ψϕ$ the width difference $ΔΓ_{s}$ is extracted, and for the first time a constraint is set on the CP-violating phase $ϕ_{s}$, although a four-fold ambiguity remains. This result is combined with other D0 measurements to yield $ΔΓ_{s}=0.13\pm0.09 {\rm ps^{-1}}$, $ϕ_{s} = -0.70^{+0.47}_{-0.39}$.

hep-ex