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

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

Generation of electromagnetic waves from 0.3 to 1.6 terahertz with a high-T-c superconducting Bi2Sr2CaCu2O8+delta intrinsic Josephson junction emitter

To obtain higher power P and frequency f emissions from the intrinsic Josephson junctions in a high-T-c superconducting Bi2Sr2CaCu2O8+delta single crystal, we embedded a rectangular stand-alone mesa of that material in a sandwich structure to allow for efficient heat exhaust. By varying the current-voltage (I-V) bias conditions and the bath temperature T-b, f is tunable from 0.3 to 1.6 THz. The maximum P of a few tens of mu W, an order of magnitude greater than from previous devices, was found at T-b similar to 55K on an inner I-V branch at the TM(1,0) cavity resonance mode frequency. The highest f of 1.6 THz was found at T-b = 10K on an inner I-V branch, but away from cavity resonance frequencies. A possible explanation is presented

Bacterial Lifestyle in a Deep-sea Hydrothermal Vent Chimney Revealed by the Genome Sequence of the Thermophilic Bacterium Deferribacter desulfuricans SSM1

The complete genome sequence of the thermophilic sulphur-reducing bacterium, Deferribacter desulfuricans SMM1, isolated from a hydrothermal vent chimney has been determined. The genome comprises a single circular chromosome of 2 234 389 bp and a megaplasmid of 308 544 bp. Many genes encoded in the genome are most similar to the genes of sulphur- or sulphate-reducing bacterial species within Deltaproteobacteria. The reconstructed central metabolisms showed a heterotrophic lifestyle primarily driven by C1 to C3 organics, e.g. formate, acetate, and pyruvate, and also suggested that the inability of autotrophy via a reductive tricarboxylic acid cycle may be due to the lack of ATP-dependent citrate lyase. In addition, the genome encodes numerous genes for chemoreceptors, chemotaxis-like systems, and signal transduction machineries. These signalling networks may be linked to this bacterium's versatile energy metabolisms and may provide ecophysiological advantages for D. desulfuricans SSM1 thriving in the physically and chemically fluctuating environments near hydrothermal vents. This is the first genome sequence from the phylum Deferribacteres

Generation of electromagnetic waves from 0.3 to 1.6 terahertz with a high- T_c superconducting Bi₂Sr₂CaCu₂O_8+δ intrinsic Josephson junction emitter

To obtain higher power P and frequency f emissions from the intrinsic Josephson junctions in a high-Tc superconducting Bi2Sr2CaCu2O8+δ single crystal, we embedded a rectangular stand-alone mesa of that material in a sandwich structure to allow for efficient heat exhaust. By varying the current-voltage (I-V) bias conditions and the bath temperature Tb, f is tunable from 0.3 to 1.6THz. The maximum P of a few tens of µW, an order of magnitude greater than from previous devices, was found at Tb ~55K on an inner I-V branch at the TM(1,0) cavity resonance mode frequency. The highest f of 1.6THz was found at Tb=10K on an inner I-V branch, but away from cavity resonance frequencies. A possible explanation is presented

Quantum terahertz electronics (QTE) using coherent radiation from high temperature superconducting Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions

An attempt has been made to improve THz radiation characteristics emitted from mesas made from Bi2Sr2CaCu2O8+δ single crystals in order to achieve an ultimate goal of high frequency quantum device applications, named here as the Quantum Terahertz Electronics (QTE). Among many requirements to be fulfilled and necessary for the development, we here made an effort to generate more intense radiation using a stand-alone type of mesa. Some characteristic features are described