16 0890-8044/13/$25.00 © 2013 IEEE hrough the utilization of elastic resources and widely deployed data centers, cloud computing has provided countless new opportunities for both new and existing applications. Existing applications, from file sharing and document synchronization to media streaming, have experienced a great leap forward in terms of system efficiency and usability through leveraging cloud computing platforms. Many of these advances have come from exploring the cloud's massive resources with computational offloading and reducing user access latencies with strategically placed cloud data centers. Recently, advances in cloud technology have expanded to allow offloading not only of traditional computation but also of such more complex tasks as high-definition 3D rendering, which turns the idea of cloud gaming into a reality. Cloud gaming, in its simplest form, renders an interactive gaming application remotely in the cloud and streams the scenes as a video sequence back to the player over the Internet. A cloud gaming player interacts with the application through a thin client, which is responsible for displaying the video from the cloud rendering server as well as collecting the player's commands and sending the interactions back to the cloud. Figure 1 shows a high-level architectural view of such a cloud gaming system with thin clients and cloud-based rendering.Onlive [1] and Gaikai [2] are two industrial pioneers of cloud gaming, both having seen success with multimillionuser bases. The recent $380 millon purchase of Gaikai by Sony [3], an industrial giant in digital entertainment and consumer electronics, shows that cloud gaming is beginning to move into the mainstream. From the perspective of industry, cloud gaming can bring immense benefits by expanding the user base to the vast number of less powerful devices that support thin clients only, particularly smartphones and tablets. As an example, the recommended system configuration for Battlefield 3, a highly popular first-person shooter game, is a quad-core CPU, 4 Gbytes RAM, 20 Gbytes storage space, and a graphics card with at least 1 Gbyte RAM (e.g., NVIDIA GEFORCE GTX 560 or ATI RADEON 6950), which already costs more than $500. The newest tablets (e.g., Apple's iPad with Retina display and Google's Nexus 10) cannot even meet the minimum system requirements that need a dual-core CPU over 2.4 GHz, 2 Gbytes RAM, and a graphics card with 512 Mbytes RAM, not to mention smartphones of which the hardware is limited by their smaller size and thermal control. Furthermore, mobile terminals have different hardware/software architecture from PCs (e.g., ARM rather than x86 for CPU), lower memory frequency and bandwidth, power limitations, and distinct operating systems. As such, the traditional console game model is not feasible for such devices, which in turn become targets for Gaikai and Onlive. Cloud gaming also reduces customer support costs since the computational hardware is now under the cloud gaming provider's full control, and offers better digital...

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Abstract-There have been significant studies on virtual machines (VMs), including their power consumption in performing different types of tasks. The VM's power consumption with network transactions, however, has seldom been examined. This paper presents an empirical study on the power consumption of typical virtualization packages while performing network tasks. We find that both Hardware Virtualization and Paravirtualization add considerable energy overhead, affecting both sending and receiving, and a busy virtualized web-server may consume 40% more energy than its non-virtualized counterparts. Our detailed profiling on packet path reveals that a VM can take 5 times more cycles to deliver a packet than a bare-metal machine, and is also much less efficient on caching. Without fundamental changes to the hypervisor-based VM architecture, we show that the use of adaptive packet buffering potentially reduces the overhead. Its practicality and effectiveness in power saving are validated through driver-level implementation and experiments.

The kelp, Laminaria saccharina, is an economically and biologically valuable seaweed used in integrated multi-trophic aquaculture. The development of the initial microscopic phase of the life cycle of this species is carried out in the laboratory. A treatment of germanium dioxide (GeO 2 ) can be applied to algal laboratory cultures to inhibit the growth of contaminating diatoms. Previous studies reported inhibitory effects also affecting the macroscopic stage of the life cycle of L. saccharina, the sporophyte, but the effects on the microscopic gametophytic life stage are unknown. To determine the effects, cultures of L. saccharina were treated with varying concentrations of GeO 2 and the resulting lengths and surface area of the juvenile sporophytes produced were measured. It was determined that GeO 2 follows a typical dose-effect pattern, increasing the growth rate of juvenile sporophytes until a critical point at which an inhibitory effect was observed. To obtain juvenile sporophytes ready for deployment to aquaculture sites in the shortest time and to successfully reduce diatom contamination, it was determined that a concentration between 0.10 and 0.50 mL of GeO 2 per litre of seawater, applied at day 8, was the most efficient.

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