240 research outputs found

    Synchro: Block-generation Protocol to Synchronously Process Cross-shard Transactions in State Sharding

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    Traditional blockchains cannot achieve the same transaction throughput as Web2, so their use cases are limited. Therefore, state sharding has been proposed to improve transaction throughput by dividing the blockchain network and managing states and transactions in parallel. However, Nightshade in the NEAR Protocol, a type of state sharding, provides a rollback protocol to cancel the generation of blocks containing inconsistent transaction results because processing cross-shard transactions (CSTXs) in a 2-phase commit may cause state inconsistency. We present a new attack that interferes with the generation of new blocks by repeatedly executing CSTXs that certainly causes state inconsistency, causing continuous rollback. We also propose a block-generation protocol called Synchro to incorporate all the state changes of each CSTX into the same block by coordinating the block prior to approving transactions in each shard. Synchro eliminates the occurrence of the state inconsistency caused by the CSTXs and the necessity of the rollback protocol. We use zero-knowledge proof to make Synchro scalable in the global validation phase. Although the actual overhead of the zero-knowledge proof has not yet been evaluated, we show that Synchro could achieve the same transaction throughput as Nightshade theoretically, depending on the future innovations in zero-knowledge proof techniques

    Lightweight High-Speed and High-Force Gripper for Assembly

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    This paper presents a novel industrial robotic gripper with a high grasping speed (maximum: 1396 mm/s), high tip force (maximum: 80 N) for grasping, large motion range, and lightweight design (0.3 kg). To realize these features, the high-speed section of the quick-return mechanism and load-sensitive continuously variable transmission mechanism are installed in the gripper. The gripper is also equipped with a self-centering function. The high grasping speed and self-centering function improve the cycle time in robotic operations. In addition, the high tip force is advantageous for stably grasping and assembling heavy objects. Moreover, the design of the gripper reduce the gripper's proportion of the manipulator's payload, thus increasing the weight of the object that can be grasped. The gripper performance was validated through kinematic and static analyses as well as experimental evaluations. This paper also presents the analysis of the self-centering function of the developed gripper

    Development and Performance of Kyoto's X-ray Astronomical SOI pixel (SOIPIX) sensor

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    We have been developing monolithic active pixel sensors, known as Kyoto's X-ray SOIPIXs, based on the CMOS SOI (silicon-on-insulator) technology for next-generation X-ray astronomy satellites. The event trigger output function implemented in each pixel offers microsecond time resolution and enables reduction of the non-X-ray background that dominates the high X-ray energy band above 5--10 keV. A fully depleted SOI with a thick depletion layer and back illumination offers wide band coverage of 0.3--40 keV. Here, we report recent progress in the X-ray SOIPIX development. In this study, we achieved an energy resolution of 300~eV (FWHM) at 6~keV and a read-out noise of 33~e- (rms) in the frame readout mode, which allows us to clearly resolve Mn-Kα\alpha and Kβ\beta. Moreover, we produced a fully depleted layer with a thickness of 500 μm500~{\rm \mu m}. The event-driven readout mode has already been successfully demonstrated.Comment: 7pages, 12figures, SPIE Astronomical Telescopes and Instrumentation 2014, Montreal, Quebec, Canada. appears as Proc. SPIE 9147, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ra

    No association between the sigma receptor type 1 gene and schizophrenia: results of analysis and meta-analysis of case-control studies

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    BACKGROUND: Several lines of evidence have supported possible roles of the sigma receptors in the etiology of schizophrenia and mechanisms of antipsychotic efficacy. An association study provided genetic evidence that the sigma receptor type 1 gene (SIGMAR1) was a possible susceptibility factor for schizophrenia, however, it was not replicated by a subsequent study. It is necessary to evaluate further the possibility that the SIGMAR1 gene is associated with susceptibility to schizophrenia. METHODS: A case-control association study between two polymorphisms of the SIGMAR1 gene, G-241T/C-240T and Gln2Pro, and schizophrenia in Japanese population, and meta-analysis including present and previous studies. RESULTS: There was no significant association of any allele or genotype of the polymorphisms with schizophrenia. Neither significant association was observed with hebephrenic or paranoid subtype of schizophrenia. Furthermore, a meta-analysis including the present and previous studies comprising 779 controls and 636 schizophrenics also revealed no significant association between the SIGMAR1 gene and schizophrenia. CONCLUSION: In view of this evidence, it is likely that the SIGMAR1 gene does not confer susceptibility to schizophrenia

    Synthesis of conjugated polymers via direct C–H/C–Cl coupling reactions using a Pd/Cu binary catalytic system

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    Direct arylation polycondensation is regarded as an efficient synthetic method for conjugated polymers. This methodology is difficult to apply to dichloroaryl monomers because of the low reactivity of the C–Cl bonds compared to that of the C–Br bonds in dibromoaryl monomers, which have been widely used in direct arylation polycondensation. In this research, direct arylation polycondensation of dichloroaryl monomers was achieved by the use of a Pd/Cu binary catalytic system. Optimisation of the molar ratio of the Pd and Cu catalyst resulted in the formation of high-molecular-weight polymers in good yields. Structural defects of the polymer at the terminal unit were minimised by logical choice of the monomer ratio on the basis of the reaction mechanism. The obtained polymer with relatively low structural defects showed a higher quantum efficiency of photoluminescence and electroluminescence than that of the polymer with irregular terminal structures
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