The quantum capacity with symmetric side channels

We present an upper bound for the quantum channel capacity that is both additive and convex. Our bound can be interpreted as the capacity of a channel for high-fidelity quantum communication when assisted by a family of channels that have no capacity on their own. This family of assistance channels, which we call symmetric side channels, consists of all channels mapping symmetrically to their output and environment. The bound seems to be quite tight, and for degradable quantum channels it coincides with the unassisted channel capacity. Using this symmetric side channel capacity, we find new upper bounds on the capacity of the depolarizing channel. We also briefly indicate an analogous notion for distilling entanglement using the same class of (one-way) channels, yielding one of the few entanglement measures that is monotonic under local operations with one-way classical communication (1-LOCC), but not under the more general class of local operations with classical communication (LOCC).Comment: 10 pages, 4 figure

Optimal superdense coding of entangled states

We present a one-shot method for preparing pure entangled states between a sender and a receiver at a minimal cost of entanglement and quantum communication. In the case of preparing unentangled states, an earlier paper showed that a 2n-qubit quantum state could be communicated to a receiver by physically transmitting only n+o(n) qubits in addition to consuming n ebits of entanglement and some shared randomness. When the states to be prepared are entangled, we find that there is a reduction in the number of qubits that need to be transmitted, interpolating between no communication at all for maximally entangled states and the earlier two-for-one result of the unentangled case, all without the use of any shared randomness. We also present two applications of our result: a direct proof of the achievability of the optimal superdense coding protocol for entangled states produced by a memoryless source, and a demonstration that the quantum identification capacity of an ebit is two qubits.Comment: Final Version. Several technical issues clarifie

Simulation Machines or Checking Action System Refinements

Action systems provide a formal approach to modelling parallel and reactive systems. They have a well established theory of refinement supported by simulation-based proof rules. This paper introduces an automatic approach for verifying action system refinements utilising standard CTL model checking. To do this, we encode each of the simulation conditions as a simulation machine, a Kripke structure on which the proof obligation can be discharged by checking that an associated CTL property holds. This procedure transforms each simulation condition into a model checking problem. Each simulation condition can then be model checked in isolation, or, if desired, together with the other simulation conditions by combining the simulation machines and the CTL properties

Proving Temporal Properties of Z Specifications Using Abstraction

This paper presents a systematic approach to proving temporal properties of arbitrary Z specifications. The approach involves (i) transforming the Z specification to an abstract temporal structure (or state transition system), (ii) applying a model checker to the temporal structure, (iii) determining whether the temporal structure is too abstract based on the model checking result and (iv) refining the temporal structure where necessary. The approach is based on existing work from the model checking literature, adapting it to Z

Compositional Verification for Object-Z

This paper presents a framework for compositional verification of Object-Z specifications. Its key feature is a proof rule based on decomposition of hierarchical Object-Z models. For each component in the hierarchy local properties are proven in a single proof step. However, we do not consider components in isolation. Instead, components are envisaged in the context of the referencing super-component and proof steps involve assumptions on properties of the sub-components. The framework is defined for linear temporal logic (LTL)

Big Data, Big Decisions: Reflections on AIS’s Role in Ethical Guidance and Oversight

This panel will introduce and debate a controversial resolution suggesting that the AIS community should take an active role in developing guidelines for the ethical practice of Big Data and analytics both in academic research and organizational practice. In addition, the resolution proposes that the AIS community should monitor and study the relevant stakeholders’ compliance with these guidelines. The panel will first provide background to the implications of Big Data and analytics based on a recent NSF-funded research agenda setting workshop. The panelists will then comment on potential benefits and potential harms from the perspective of key stakeholder segments: individual citizens, organizations, and society as a whole. The panel will invite the audience to debate the major provocation: What is the appropriate role for the AIS community in ethical leadership on the uses of Big Data and analytics

Dietary red meat aggravates dextran sulfate sodium-induced colitis in mice whereas resistant starch attenuates inflammation

Although a genetic component has been identified as a risk factor for developing inflammatory bowel disease, there is evidence that dietary factors also play a role in the development of this disease. Aims The aim of this study was to determine the effects of feeding a red meat diet with and without resistant starch (RS) to mice with dextran sulfate sodium (DSS)-induced colitis. Methods Colonic experimental colitis was induced in Balb/c mice using DSS. The severity of colitis was evaluated based on a disease activity index (based on bodyweight loss, stool consistency, rectal bleeding, and overall condition of the animal) and a histological score. Estimations were made of numbers of a range of different bacteria in the treatment pools of cecal digesta using quantitative real-time PCR. Results Consumption of a diet high in red meat increased DSS-induced colitis as evidenced by higher disease activity and histopathological scores. Addition of RS to the red meat diet exerted a beneficial effect in acute DSS-induced colitis. Subjective analysis of numbers of a range of bacterial targets suggest changes in the gut microbiota abundance were induced by red meat and RS treatments and these changes could contribute to the reported outcomes. Conclusions A dietary intake of red meat aggravates DSS-induced colitis whereas co-consumption of resistant starch reduces the severity of colitis.This work was supported by the National Health and Medical Research Council (grant ID 535079) and CSIRO Preventative Health National Research Flagship

Accumulation of promutagenic DNA adducts in the mouse distal colon after consumption of heme does not induce colonic neoplasms in the western diet model of spontaneous colorectal cancer

Author version made available in accordance with Publisher copyright policy.Scope: Red meat is considered a risk factor for colorectal cancer (CRC). Heme is considered to promote colonic hyperproliferation and cell damage. Resistant starch (RS) is a food that ferments in the colon with studies demonstrating protective effects against CRC. By utilizing the western diet model of spontaneous CRC, we determined if feeding heme (as hemin chloride) equivalent to a high red meat diet would increase colonic DNA adducts and CRC and whether RS could abrogate such effects. Methods and results: Four groups of mice: control, heme, RS and heme + RS were fed diets for 1 or 18 months. Colons were analyzed for apoptosis, proliferation, DNA adducts “8-hydroxy-2-deoxyguanosine” and “O6-methyl-2-deoxyguanosine” (O6MeG), and neoplasms. In the short term, heme increased cell proliferation (p < 0.05). Changes from 1 to 18 months showed increased cell proliferation (p<0.01) and 8-hydroxy-2-deoxyguanosine adducts (p < 0.05) in all groups, but only heme-fed mice showed reduced apoptosis (p < 0.01) and increasedO6MeGadducts (p<0.01). The incidence of colon neoplasms was not different between any interventions. Conclusion: We identified heme to increase proliferation in the short term, inhibit apoptosis over the long term, and increase O6MeG adducts in the colon over time although these changes did not affect colonic neoplasms within this mouse model.Funding for this project was provided by the National Health and Medical Research Council of Australia (Project number 535079).We would like to acknowledge the Royal Society of Edinburgh for funding a visit for Dr. SilviaGratz fromUKto Australia to carry out work associated with this project

Delta chirality ruthenium ‘light-switch’ complexes can bind in the minor groove of DNA with five different binding modes

[Ru(phen)2(dppz)]2+ has been studied since the 1990s due to its “light-switch” properties. It can be used as a luminescent DNA probe, with emission switched on through DNA binding. The luminescence observed is dependent on the solvent accessibility of the pyrazine nitrogen atoms, and therefore is sensitive to changes in both binding site of the cation and chromophore orientation. The compound is also chiral, and there are distinct differences between the enantiomers in terms of the emission behaviour when bound to a variety of DNA sequences. Whilst a number of binary DNA-complex X-ray crystal structures is available, most include the Λ enantiomer, and there is very little structural information about binding of the Δ enantiomer. Here we present the first X-ray crystal structure of a Δ enantiomer bound to well-matched DNA, in the absence of the other, Λ, enantiomer. We show how the binding site observed here can be related to a more general pattern of motifs in the crystallographic literature and propose that the Δ enantiomer can bind with five different binding modes, offering a new hypothesis for the interpretation of solution data