29 research outputs found
A QKD Protocol Extendable to Support Entanglement and Reduce Unauthorized Information Gain by Randomizing the Bases Lists with Key Values and Invalidate Explicit Privacy Amplification
This paper suggests an improvement to the BB84 scheme in Quantum key
distribution. The original scheme has its weakness in letting quantifiably more
information gain to an eavesdropper during public announcement of unencrypted
bases lists. The security of the secret key comes at the expense of the final
key length. We aim at exploiting the randomness of preparation (measurement)
basis and the bit values encoded (observed), so as to randomize the bases lists
before they are communicated over the public channel. A proof of security is
given for our scheme and proven that our protocol results in lesser information
gain by Eve in comparison with BB84 and its other extensions. Moreover, an
analysis is made on the feasibility of our proposal as such and to support
entanglement based QKD. The performance of our protocol is compared in terms of
the upper and lower bounds on the tolerable bit error rate. We also quantify
the information gain (by Eve) mathematically using the familiar approach of the
concept of Shannon entropy. The paper models the attack by Eve in terms of
interference in a multi-access quantum channel. Besides, this paper also hints
at the invalidation of a separate privacy amplification step in the
"prepare-and-measure" protocols in general.Comment: 13 pages, 1 figure, submitted for review to the USENIX 200
MICU1 Motifs Define Mitochondrial Calcium Uniporter Binding and Activity
SummaryResting mitochondrial matrix Ca2+ is maintained through a mitochondrial calcium uptake 1 (MICU1)-established threshold inhibition of mitochondrial calcium uniporter (MCU) activity. It is not known how MICU1 interacts with MCU to establish this Ca2+ threshold for mitochondrial Ca2+ uptake and MCU activity. Here, we show that MICU1 localizes to the mitochondrial matrix side of the inner mitochondrial membrane and MICU1/MCU binding is determined by a MICU1 N-terminal polybasic domain and two interacting coiled-coil domains of MCU. Further investigation reveals that MICU1 forms homo-oligomers, and this oligomerization is independent of the polybasic region. However, the polybasic region confers MICU1 oligomeric binding to MCU and controls mitochondrial Ca2+ current (IMCU). Moreover, MICU1 EF hands regulate MCU channel activity, but do not determine MCU binding. Loss of MICU1 promotes MCU activation leading to oxidative burden and a halt to cell migration. These studies establish a molecular mechanism for MICU1 control of MCU-mediated mitochondrial Ca2+ accumulation, and dysregulation of this mechanism probably enhances vascular dysfunction
MIRO-1 Determines Mitochondrial Shape Transition upon GPCR Activation and Ca^(2+) Stress
Mitochondria shape cytosolic calcium ([Ca^(2+)]_c) transients and utilize the mitochondrial Ca_2^+ ([Ca^(2+)]_m) in exchange for bioenergetics output. Conversely, dysregulated [Ca^(2+)]_c causes [Ca^(2+)]_m overload and induces permeability transition pore and cell death. Ablation of MCU-mediated Ca^(2+) uptake exhibited elevated [Ca^(2+)]_c and failed to prevent stress-induced cell death. The mechanisms for these effects remain elusive. Here, we report that mitochondria undergo a cytosolic Ca^(2+)-induced shape change that is distinct from mitochondrial fission and swelling. [Ca^(2+)]_c elevation, but not MCU-mediated Ca^(2+) uptake, appears to be essential for the process we term mitochondrial shape transition (MiST). MiST is mediated by the mitochondrial protein Miro1 through its EF-hand domain 1 in multiple cell types. Moreover, Ca^(2+)-dependent disruption of Miro1/KIF5B/tubulin complex is determined by Miro1 EF1 domain. Functionally, Miro1-dependent MiST is essential for autophagy/mitophagy that is attenuated in Miro1 EF1 mutants. Thus, Miro1 is a cytosolic Ca^(2+) sensor that decodes metazoan Ca^(2+) signals as MiST
MIRO-1 Determines Mitochondrial Shape Transition upon GPCR Activation and Ca^(2+) Stress
Mitochondria shape cytosolic calcium ([Ca^(2+)]_c) transients and utilize the mitochondrial Ca_2^+ ([Ca^(2+)]_m) in exchange for bioenergetics output. Conversely, dysregulated [Ca^(2+)]_c causes [Ca^(2+)]_m overload and induces permeability transition pore and cell death. Ablation of MCU-mediated Ca^(2+) uptake exhibited elevated [Ca^(2+)]_c and failed to prevent stress-induced cell death. The mechanisms for these effects remain elusive. Here, we report that mitochondria undergo a cytosolic Ca^(2+)-induced shape change that is distinct from mitochondrial fission and swelling. [Ca^(2+)]_c elevation, but not MCU-mediated Ca^(2+) uptake, appears to be essential for the process we term mitochondrial shape transition (MiST). MiST is mediated by the mitochondrial protein Miro1 through its EF-hand domain 1 in multiple cell types. Moreover, Ca^(2+)-dependent disruption of Miro1/KIF5B/tubulin complex is determined by Miro1 EF1 domain. Functionally, Miro1-dependent MiST is essential for autophagy/mitophagy that is attenuated in Miro1 EF1 mutants. Thus, Miro1 is a cytosolic Ca^(2+) sensor that decodes metazoan Ca^(2+) signals as MiST