Based on the Kubo formula for an electron tunneling junction, we revisit the nonequilibrium transport properties through a quantum dot. Since the Fermi level of the quantum dot is set by the conduction electrons of th...Based on the Kubo formula for an electron tunneling junction, we revisit the nonequilibrium transport properties through a quantum dot. Since the Fermi level of the quantum dot is set by the conduction electrons of the leads, we calculate the electron current from the left side by assuming the quantum dot coupled to the right lead as another side of the tunneling junction, and the other way round is used to calculate the current from the right side. By symmetrizing these two currents, an effective local density states on the dot can be obtained, and is discussed at high and low temperatures, respectively.展开更多
The human gene ATP 13A2 has been proposed to code for an ATP powered ion transporter of the PsB subfamily. Mutations of the human gene ATP1 3A2 were found to underlie an autosomal recessive form of early-onset parkins...The human gene ATP 13A2 has been proposed to code for an ATP powered ion transporter of the PsB subfamily. Mutations of the human gene ATP1 3A2 were found to underlie an autosomal recessive form of early-onset parkinsonism （PD） with pyramidal degeneration and dementia. The ion transported by the ATP13A2 pump is not known, but several studies have shown that the Ps-ATPases influence the homeostasis of intracellular Ca2＋, and thus it has been suggested that they transport Ca2＋. In order to evaluate this possibility Chinese hamster ovary （CHO） cells stably expressing the human ATP13A2 protein have been obtained and the Ca2＋ transport activity of ATP 13A2 was assessed by measuring the ATP-dependent uptake of Ca2＋ into microsomal vesicles. As a positive control vesicles containing the human plasma membrane Ca2＋ pump （PMCA） were used. No significant differences were found between vesicles containing the ATP 13A2 protein and the control. Moreover, Ca2＋ was unable to induce the formation of the P-ATPase acylphosphate intermediate in vesicles containing the expressed ATPl3A2. These results favor the idea that the ATPI3A2 does not transport Ca2＋.展开更多
Because of the concise functionality of oblivious transfer （OT） protocols, they have been widely used as building blocks in secure multiparty computation and high-level protocols. The security of OT protocols built ...Because of the concise functionality of oblivious transfer （OT） protocols, they have been widely used as building blocks in secure multiparty computation and high-level protocols. The security of OT protocols built upon classical number theoretic problems, such as the discrete logarithm and factoring, however, is threatened as a result of the huge progress in quantum computing. Therefore, post-quantum cryptography is needed for protocols based on classical problems, and several proposals for post-quantum OT protocols exist. However, most post-quantum cryptosystems present their security proof only in the context of classical adversaries, not in the quantum setting. In this paper, we close this gap and prove the security of the lattice-based OT protocol proposed by Peikert et al. （CRYPTO, 2008）, which is universally composably secure under the assumption of learning with errors hardness, in the quantum setting. We apply three general quantum security analysis frameworks. First, we apply the quantum lifting theorem proposed by Unruh （EUROCRYPT, 2010） to prove that the security of the lattice-based OT protocol can be lifted into the quantum world. Then, we apply two more security analysis frameworks specified for post-quantum cryptographic primitives, i.e., simple hybrid arguments （CRYPTO, 2011） and game-preserving reduction （PQCrypto, 2014）.展开更多
Flux transfer events （FTEs） are local transient magnetic reconnections at the magnetopause （MP） that provide channels for transport of solar wind energy and plasma into the magnetosphere （MSP）. All current theor...Flux transfer events （FTEs） are local transient magnetic reconnections at the magnetopause （MP） that provide channels for transport of solar wind energy and plasma into the magnetosphere （MSP）. All current theoretical models suggest that FTEs are open-flux ropes; however, global simulations show that they contain both open and closed magnetic fields. To clarify this to- pology, we analyzed 441 events observed by THEMIS and investigated their magnetic topologies. Only one type of open field line was detected in most magnetosheath （MSH） FTEs, independent of the polarity of the Bn bipolar signatures. Newly formed MSH field lines were also observed. In the all MP boundary layers FTEs and most MSP FTEs, multiple types of topologies were observed, irrelevant to the Bn bipolar polarity. Closed field lines were found in all MP boundary layers and MSP FTEs. Meanwhile very few boundary FTEs contained the newly formed MSH flux. In some situations, only closed field lines were seen in MSP FTEs, which are referred to as the fossil FTEs. These results, which largely differ from the traditional view, demonstrate the existence of complex magnetic topologies in FTEs. Based on these results, we propose a new 3D FTE picture to modify the current FTE models.展开更多
基金国家自然科学基金，the Special Fund for State Key Basic Research Projects of China under
文摘Based on the Kubo formula for an electron tunneling junction, we revisit the nonequilibrium transport properties through a quantum dot. Since the Fermi level of the quantum dot is set by the conduction electrons of the leads, we calculate the electron current from the left side by assuming the quantum dot coupled to the right lead as another side of the tunneling junction, and the other way round is used to calculate the current from the right side. By symmetrizing these two currents, an effective local density states on the dot can be obtained, and is discussed at high and low temperatures, respectively.
文摘The human gene ATP 13A2 has been proposed to code for an ATP powered ion transporter of the PsB subfamily. Mutations of the human gene ATP1 3A2 were found to underlie an autosomal recessive form of early-onset parkinsonism （PD） with pyramidal degeneration and dementia. The ion transported by the ATP13A2 pump is not known, but several studies have shown that the Ps-ATPases influence the homeostasis of intracellular Ca2＋, and thus it has been suggested that they transport Ca2＋. In order to evaluate this possibility Chinese hamster ovary （CHO） cells stably expressing the human ATP13A2 protein have been obtained and the Ca2＋ transport activity of ATP 13A2 was assessed by measuring the ATP-dependent uptake of Ca2＋ into microsomal vesicles. As a positive control vesicles containing the human plasma membrane Ca2＋ pump （PMCA） were used. No significant differences were found between vesicles containing the ATP 13A2 protein and the control. Moreover, Ca2＋ was unable to induce the formation of the P-ATPase acylphosphate intermediate in vesicles containing the expressed ATPl3A2. These results favor the idea that the ATPI3A2 does not transport Ca2＋.
基金Project supported by the National Key R&D Program of China(No.2017YFB0802000)the National Natural Science Foundation of China(Nos.61672412,61472309,and 61572390)the China Scholarship Council(No.201406960041)
文摘Because of the concise functionality of oblivious transfer （OT） protocols, they have been widely used as building blocks in secure multiparty computation and high-level protocols. The security of OT protocols built upon classical number theoretic problems, such as the discrete logarithm and factoring, however, is threatened as a result of the huge progress in quantum computing. Therefore, post-quantum cryptography is needed for protocols based on classical problems, and several proposals for post-quantum OT protocols exist. However, most post-quantum cryptosystems present their security proof only in the context of classical adversaries, not in the quantum setting. In this paper, we close this gap and prove the security of the lattice-based OT protocol proposed by Peikert et al. （CRYPTO, 2008）, which is universally composably secure under the assumption of learning with errors hardness, in the quantum setting. We apply three general quantum security analysis frameworks. First, we apply the quantum lifting theorem proposed by Unruh （EUROCRYPT, 2010） to prove that the security of the lattice-based OT protocol can be lifted into the quantum world. Then, we apply two more security analysis frameworks specified for post-quantum cryptographic primitives, i.e., simple hybrid arguments （CRYPTO, 2011） and game-preserving reduction （PQCrypto, 2014）.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41274167 & 41374166)the ESA 2013–2014 Guest Investigator Programworking group sponsored by ISSI Bern
文摘Flux transfer events （FTEs） are local transient magnetic reconnections at the magnetopause （MP） that provide channels for transport of solar wind energy and plasma into the magnetosphere （MSP）. All current theoretical models suggest that FTEs are open-flux ropes; however, global simulations show that they contain both open and closed magnetic fields. To clarify this to- pology, we analyzed 441 events observed by THEMIS and investigated their magnetic topologies. Only one type of open field line was detected in most magnetosheath （MSH） FTEs, independent of the polarity of the Bn bipolar signatures. Newly formed MSH field lines were also observed. In the all MP boundary layers FTEs and most MSP FTEs, multiple types of topologies were observed, irrelevant to the Bn bipolar polarity. Closed field lines were found in all MP boundary layers and MSP FTEs. Meanwhile very few boundary FTEs contained the newly formed MSH flux. In some situations, only closed field lines were seen in MSP FTEs, which are referred to as the fossil FTEs. These results, which largely differ from the traditional view, demonstrate the existence of complex magnetic topologies in FTEs. Based on these results, we propose a new 3D FTE picture to modify the current FTE models.
