The private capacity of quantum channels is not additive

Recently there has been considerable activity on the subject of additivity of various quantum channel capacities. Here, we construct a family of channels with sharply bounded classical, hence private capacity. On the other hand, their quantum capacity when combined with a zero private (and zero quantum) capacity erasure channel, becomes larger than the previous classical capacity. As a consequence, we can conclude for the first time that the classical private capacity is non-additive. In fact, in our construction even the quantum capacity of the tensor product of two channels can be greater than the sum of their individual classical private capacities. We show that this violation occurs quite generically: every channel can be embedded into our construction, and a violation occurs whenever the given channel has larger entanglement assisted quantum capacity than (unassisted) classical capacity.Comment: 4+4 pages, 2 eps figures. V2 has title and abstract changed; its new structure reflects the final version of a main paper plus appendices containing mathematical detail

Structural Studies on a Mitochondrial Glyoxalase II

Glyoxalase 2 is a β-lactamase fold-containing enzyme that appears to be involved with cellular chemical detoxification. Although the cytoplasmic isozyme has been characterized from several organisms, essentially nothing is known about the mitochondrial proteins. As a first step in understanding the structure and function of mitochondrial glyoxalase 2 enzymes, a mitochondrial isozyme (GLX2-5) from Arabidopsis thaliana was cloned, overexpressed, purified, and characterized using metal analyses, EPR and 1H NMR spectroscopies, and x-ray crystallography. The recombinant enzyme was shown to bind 1.04 ± 0.15 eq of iron and 1.31 ± 0.05 eq of Zn(II) and to exhibit kcat and Km values of 129 ± 10 s-1 and 391 ± 48 μm, respectively, when using S-d-lactoylglutathione as the substrate. EPR spectra revealed that recombinant GLX2-5 contains multiple metal centers, including a predominant Fe(III)Z-n(II) center and an anti-ferromagnetically coupled Fe(III)Fe(II) center. Unlike cytosolic glyoxalase 2 from A. thaliana, GLX2-5 does not appear to specifically bind manganese. 1H NMR spectra revealed the presence of at least eight paramagnetically shifted resonances that arise from protons in close proximity to a Fe(III)Fe(II) center. Five of these resonances arose from solvent-exchangeable protons, and four of these have been assigned to NH protons on metal-bound histidines. A 1.74-Å resolution crystal structure of the enzyme revealed that although GLX2-5 shares a number of structural features with human GLX2, several important differences exist. These data demonstrate that mitochondrial glyoxalase 2 can accommodate a number of different metal centers and that the predominant metal center is Fe(III)Zn(II)

Herders’ Attitude and Decision Making in Stocking Rates and Implication for Grassland Management in China

Overgrazing is widely acknowledged to be the main driver of grassland degradation. Governments seeking to address the grassland degradation problem have therefore focused on policies designed to reduce overgrazing. The Chinese government has implemented a series of policies with the aim of protecting the grasslands from more serious degradation. The efficacy of these policies has been questioned given that, since their introduction, stocking rates have remained high in many affected areas. It has been suggested that the government should enhance grassland monitoring and the punishment of overgrazing. Increasing penalties would reduce stocking rates, however that is likely to cause more social and economic problems. A survey of 1588 herders found that 40% consider the government should set a grass-animal balance rule and implement it strictly, and 30% think the government should only recommend a grass-animal balance rule for herders to follow，only 30% of herders were likely to set the stocking rate by themselves. An analysis of the survey data showed that household expenditure (food, house, clothing, medical expenses) was an important driver of overgrazing. Most herders depend upon their livestock for income; only 3% have a part-time job, compared to over 30% of all Chinese farmers. On average 70% of a herders’ income comes from livestock production and around 26% comes from subsidies. The contingent model developed found that, increasing subsidies with punishment for non-compliance, should reduce stocking rates and help maintain herders’ income, but not to the level required to alleviate poverty and unsustainable. We suggest that herders need training to improve their business skills so they can move from a focus on survival to one where optimising production and better marketing, are the aims of their livestock enterprise. Demonstration farms need to be part of this training

Separability of rank two quantum states on multiple quantum spaces

Explicit sufficient and necessary conditions for separability of $N$-dimensional rank two multiparty quantum mixed states are presented. A nonseparability inequality is also given, for the case where one of the eigenvectors corresponding to nonzero eigenvalues of the density matrix is maximally entangled.Comment: 10 pages, Late

BSMBench: A flexible and scalable HPC benchmark from beyond the standard model physics

Lattice Quantum ChromoDynamics (QCD), and by extension its parent field, Lattice Gauge Theory (LGT), make up a significant fraction of supercomputing cycles worldwide. As such, it would be irresponsible not to evaluate machines’ suitability for such applications. To this end, a benchmark has been developed to assess the performance of LGT applications on modern HPC platforms. Distinct from previous QCD-based benchmarks, this allows probing the behaviour of a variety of theories, which allows varying the ratio of demands between on- node computations and inter-node communications. The results of testing this benchmark on various recent HPC platforms are presented, and directions for future development are discussed

Spectroscopic Studies on Cobalt(II)-Substituted Metallo-β-lactamase ImiS from \u3cem\u3eAeromonas veronii\u3c/em\u3e bv. \u3cem\u3esobria\u3c/em\u3e

In an effort to probe the structure of a group Bb metallo-β-lactamase, Co(II)-substituted ImiS was prepared and characterized by electronic absorption, NMR, and EPR spectroscopies. ImiS containing 1 equiv of Co(II) (Co(II)1-ImiS) was shown to be catalytically active. Electronic absorption studies of Co(II)1-ImiS revealed the presence of two distinct features:  (1) an intense sulfur to Co(II) ligand to metal charge transfer band and (2) less intense, Co(II) ligand field transitions that suggest 4-coordinate Co(II) in Co(II)1-ImiS. 1H NMR studies of Co(II)1-ImiS suggest that one histidine, one aspartic acid, and one cysteine coordinate the metal ion in Co(II)1-ImiS. The addition of a second Co(II) to Co(II)1-ImiS did not result in any additional solvent-exchangeable NMR resonances, strongly suggesting that the second Co(II) does not bind to a site with histidine ligands. EPR studies reveal that the metal ion in Co(II)1-ImiS is 4-coordinate and that the second Co(II) is 5/6 coordinate. Taken together, these data indicate that the catalytic site in ImiS is the consensus Zn2 site, in which Co(II) (and by extrapolation Zn(II)) is 4-coordinate and bound by Cys221, His263, Asp120, and probably one solvent water molecule. These studies also show that the second, inhibitory metal ion does not bind to the consensus Zn1 site and that the metal ion binds at a site significantly removed from the active site. These results give the first structural information on metallo-β-lactamase ImiS and suggest that the second metal binding site in ImiS may be targeted for inhibitors

Vulnerability of "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in Quantum Cryptography"

In this paper we review and comment on "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in quantum cryptography", [M. Peev et al., Int. J. Quant. Inform., 3, 225, (2005)]. In particular, we point out that the proposed primitive is not secure when used in a generic protocol, and needs additional authenticating properties of the surrounding quantum-cryptographic protocol.Comment: 6 page

Repair of oxidative DNA base damage in the host genome influences the HIV integration site sequence preference

Host base excision repair (BER) proteins that repair oxidative damage enhance HIV infection. These proteins include the oxidative DNA damage glycosylases 8-oxo-guanine DNA glycosylase (OGG1) and mutY homolog (MYH) as well as DNA polymerase beta (Polβ). While deletion of oxidative BER genes leads to decreased HIV infection and integration efficiency, the mechanism remains unknown. One hypothesis is that BER proteins repair the DNA gapped integration intermediate. An alternative hypothesis considers that the most common oxidative DNA base damages occur on guanines. The subtle consensus sequence preference at HIV integration sites includes multiple G:C base pairs surrounding the points of joining. These observations suggest a role for oxidative BER during integration targeting at the nucleotide level. We examined the hypothesis that BER repairs a gapped integration intermediate by measuring HIV infection efficiency in Polβ null cell lines complemented with active site point mutants of Polβ. A DNA synthesis defective mutant, but not a 59dRP lyase mutant, rescued HIV infection efficiency to wild type levels; this suggeted Polβ DNA synthesis activity is not necessary while 59dRP lyase activity is required for efficient HIV infection. An alternate hypothesis that BER events in the host genome influence HIV integration site selection was examined by sequencing integration sites in OGG1 and MYH null cells. In the absence of these 8-oxo-guanine specific glycosylases the chromatin elements of HIV integration site selection remain the same as in wild type cells. However, the HIV integration site sequence preference at G:C base pairs is altered at several positions in OGG1 and MYH null cells. Inefficient HIV infection in the absence of oxidative BER proteins does not appear related to repair of the gapped integration intermediate; instead oxidative damage repair may participate in HIV integration site preference at the sequence level. © 2014 Bennett et al