One major concern regarding long-term manned space missions is the effect of accumulative doses of space radiation (the mean daily dose is 0.2 ~ 1 mSv). Such missions will inevitably expose astronauts to significant doses, and thus are expected to increase the risks of radiation-related carcinogenicity, neurotoxicity, and lifespan changes. These effects occur by nuclear and cytosol dysfunction, mitochondrial damage, and particular changes in signal transduction or protein synthesis. In addition, microgravity may affect cellular metabolisms, signal transduction, etc., and might lead to synergistic effects with space radiation, which could result in further risk. Because these effects will almost certainly involve cellular signaling, transcriptomics and proteomics will be powerful tools in their analysis. In order to suitably respond to all these risks, both protective measures based on physical and biological principles, and effective intra-flight assessment of the levels of radiation exposure will be required. In this article, the categories of cell death-i.e., apoptosis, necrosis and autophagy-and the recent studies on these mechanisms are reviewed.

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Smart Cluster Network (SCnet) is a high performanceVirtual Interface (VI) Architecture communication system for UNIX TM systems connected with Fujitsu's Synfinity-0 System Area Network (SAN). It is the first UNIX TM VI Architecture system that achieves "Full Conformance," as defined by Intel Corp. This paper describes the design of SCnet, focusing on multiple Network Interface Card (NIC) support for load balance, inter-process protection, memory registration, and communication protocols. The paper presents the main problems faced and our solutions for them. We propose extensions needed to support the VI Architecture effectively on current systems. We evaluated the SCnet performance experimentally using a two node cluster system connected with the Fujitsu's Synfinity-0 SAN. Latency as low as 42 microseconds, and throughput as high as 108 MBytes/sec is achieved using a single NIC. When using 2 NICs per node throughput of 210 MBytes/sec is achieved.