New class of quantum error-correcting codes for a bosonic mode

We construct a new class of quantum error-correcting codes for a bosonic mode which are advantageous for applications in quantum memories, communication, and scalable computation. These 'binomial quantum codes' are formed from a finite superposition of Fock states weighted with binomial coefficients. The binomial codes can exactly correct errors that are polynomial up to a specific degree in bosonic creation and annihilation operators, including amplitude damping and displacement noise as well as boson addition and dephasing errors. For realistic continuous-time dissipative evolution, the codes can perform approximate quantum error correction to any given order in the timestep between error detection measurements. We present an explicit approximate quantum error recovery operation based on projective measurements and unitary operations. The binomial codes are tailored for detecting boson loss and gain errors by means of measurements of the generalized number parity. We discuss optimization of the binomial codes and demonstrate that by relaxing the parity structure, codes with even lower unrecoverable error rates can be achieved. The binomial codes are related to existing two-mode bosonic codes but offer the advantage of requiring only a single bosonic mode to correct amplitude damping as well as the ability to correct other errors. Our codes are similar in spirit to 'cat codes' based on superpositions of the coherent states, but offer several advantages such as smaller mean number, exact rather than approximate orthonormality of the code words, and an explicit unitary operation for repumping energy into the bosonic mode. The binomial quantum codes are realizable with current superconducting circuit technology and they should prove useful in other quantum technologies, including bosonic quantum memories, photonic quantum communication, and optical-to-microwave up- and down-conversion.Comment: Published versio

The distribution of pelagic sound scattering layers across the southwest Indian Ocean

Ship of Opportunity Data were sourced from the Integrated Marine Observing System (IMOS)—an initiative of the Australian Government being conducted as part of the National Collaborative Research Infrastructure Strategy and the Super Science Initiative. Other acoustic data were collected as part of the Southwest Indian Ocean Seamounts Project (http://www.iucn.org/marine/seamounts) which was supported supported by the EAF Nansen Project, the Food and Agriculture Organization of the United Nations, the Global Environment Facility, the International Union for the Conservation of Nature, the Natural Environment Research Council (Grant NE/F005504/1), the Leverhulme Trust (Grant F00390C) and the Total Foundation. We thank the Masters, officers, crews and science parties of cruises DFN 2009-410 and JCO66/67 for their assistance during echosounder calibration and data acquisition, and two anonymous reviewers for their comments. PHBS was supported by the German National Academic Foundation, a Cusanuswerk doctoral fellowship, and a Lesley & Charles Hilton-Brown Scholarship.Shallow and deep scattering layers (SLs) were surveyed with split-beam echosounders across the southwest Indian Ocean (SWIO) to investigate their vertical and geographical distribution. Cluster analysis was employed to objectively classify vertical backscatter profiles. Correlations between backscatter and environmental covariates were modelled using generalized additive mixed models (GAMMs) with spatial error structures. Structurally distinct SL regimes were found across the Subantarctic Front. GAMMs indicated a close relationship between sea surface temperature and mean volume backscatter, with significantly elevated backscatter in the subtropical convergence zone. The heterogeneous distribution of scattering layer biota reflects the biogeographic zonation of the survey area and is likely to have implications for predator foraging and carbon cycling in the Indian Ocean.PostprintPeer reviewe

Hydromorphological frameworks: emerging trajectories

This paper forms a postscript to a Special Issue that reports on research funded through the European Union’s FP7 programme under Grant Agreement No. 282656 (REFORM)

Affine Constellations Without Mutually Unbiased Counterparts

It has been conjectured that a complete set of mutually unbiased bases in a space of dimension d exists if and only if there is an affine plane of order d. We introduce affine constellations and compare their existence properties with those of mutually unbiased constellations, mostly in dimension six. The observed discrepancies make a deeper relation between the two existence problems unlikely.Comment: 8 page

Characterization of the stimulators of protein-directed ribosomal frameshifting in Theiler's murine encephalomyelitis virus.

Many viruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to express additional proteins or to produce frameshift and non-frameshift protein products at a fixed stoichiometric ratio. PRF is also utilized in the expression of a small number of cellular genes. Frameshifting is typically stimulated by signals contained within the mRNA: a 'slippery' sequence and a 3'-adjacent RNA structure. Recently, we showed that -1 PRF in encephalomyocarditis virus (EMCV) is trans-activated by the viral 2A protein, leading to a temporal change in PRF efficiency from 0% to 70% during virus infection. Here we analyzed PRF in the related Theiler's murine encephalomyelitis virus (TMEV). We show that 2A is also required for PRF in TMEV and can stimulate PRF to levels as high as 58% in rabbit reticulocyte cell-free translations and 81% during virus infection. We also show that TMEV 2A trans-activates PRF on the EMCV signal but not vice versa. We present an extensive mutational analysis of the frameshift stimulators (mRNA signals and 2A protein) analysing activity in in vitro translation, electrophoretic mobility shift and in vitro ribosome pausing assays. We also investigate the PRF mRNA signal with RNA structure probing. Our results substantially extend previous characterization of protein-stimulated PRF

An interdisciplinary corpus-based analysis of the translation of كرامة (karāma, ‘dignity’) and its collocates in Arabic-English constitutions

This interdisciplinary study examines whether instances, variants, and translations of the human rights term كرامة (karāma, 'dignity') in the Leeds Parallel Corpus of Arabic-English Constitutions imply a shared understanding of the term from source to target text (i.e. from Arabic to English). Our approach combines quantitative and qualitative techniques from Corpus Linguistics and Arabic legal translation and contributes to theory and practice in the emerging field of computer-assisted legal linguistics and translation. Our research methodology includes: specification of morphological variants of كرامة in the Arabic corpus; close scrutiny of parallel concordance lines; and analysis of the semantic prosody of target terms through collocation discovery. In total, we identify 65 instances of كرامة (or one of its variants) in the Arabic data, where raw frequency of the term is highest in the constitutions of Egypt and Sudan, and missing in the constitution of Palestine. We find that while the indefinite noun كرامة is always translated as ‘dignity’ in English, the definite form (الكرامة, al-karāma) is often rendered via a qualifying adjective plus the word 'treatment'. We also find that the combination of الكرامة and negation leads to qualification of ‘treatment’ with notions of humiliation and cruelty. This is further evidenced via collocation discovery over the Arabic and English sub-corpora of 19 constitutions. This suggests a common understanding of كرامة and dignity as an inviolable human right across these different languages and cultures, fostered perhaps by the theological significance of these terms

The Emissions of Water Vapour and NOx from Modelled Hydrogen-Fuelled Aircraft and the Impact of NOx Reduction on Climate Compared with Kerosene-Fuelled Aircraft

A kerosene fuelled aircraft was modelled within a performance tool and fuel burn and the emissions of nitrogen oxides (NOx) and water vapour at different stages of flight throughout the mission were estimated. Adaptions were made to engine and aircraft parameters within the performance tool to accommodate a liquid hydrogen fuel over the same given mission. Once an iterative design process had been completed to ensure the aircraft could perform the given mission, the performance tool was again used to calculate total fuel burn. Fuel burn results alongside predicted emission indices were used to estimate the emissions of NOx, water vapour from hydrogen-fuelled aircraft. The use of hydrogen fuel over kerosene fuel in the modelled aircraft resulted in the removal of carbon-based emission species alongside 86% reduction in NOx and 4.3 times increase in water vapour emission. The climate impact of this switch with the reduction in NOx emission was assessed by a 3D global atmospheric chemistry and transport model, STOCHEM-CRI, which found a significant reduction in the concentration of a potent greenhouse gas, ozone, and an oxidizing agent, OH, by up to 6% and 25%, respectively. The reduction of OH levels could induce a positive radiative forcing effect as the lifetime of another important greenhouse gas, methane, is increased. However, the magnitude of this increase is very small (~0.3%), thus the overall impact of the reduction in NOx emissions is likely to have a net negative radiative forcing effect, improving aviation’s impact on the environment. However, further work is warranted on effects of other emission species, specifically water vapour, particulate matter and unburned hydrogen

Lumps and bumps of the gingiva : a pathological miscellany

Lesions of the gingivae are amongst the commonest lesions seen in patients and the vast majority are reactive hyperplasias, related to a number of chronic irritant stimuli. However, there are a number of entities that have a predilection for the gingivae, which are much less common in other parts of the oral cavity. The purpose of this paper is to discuss the clinical and histological differential diagnoses when presented with a lump on the gingivae, including the approach to diagnosis and diagnostic pitfalls

Enhanced pelagic biomass around coral atolls

T.B.L. was supported by the Marine Biodiversity Hub through the Australian Government’s National Environmental Research Program (NERP). P.H.B.-S. was supported by a Cusanuswerk doctoral fellowship, a Lesley & Charles Hilton-Brown Scholarship, University of St. Andrews, and a grant from the Fisheries Society of the British Isles. M.J.C. was supported by Australian Research Council grant FS110200057.Understanding the processes driving the distribution of mid-water prey such as euphausiids and lanternfish is important for effective management and conservation. In the vicinity of abrupt topographic features such as banks, seamounts and shelf-breaks, mid-water faunal biomass is often elevated, making these sites candidates for special protection. We investigated the spatial distribution of water column acoustic backscatter - a proxy for macrozoo - plankton and fish biomass - in the 9 km transition zone between the pelagos and coral atolls in the Chagos Archipelago (6° N, 72° E). The purpose was to determine the magnitude and distance over which bathymetry may enhance biomass in the mid-water, and thereby identify the scale over which static topographic features could influence the open ocean. Two distinct sound scattering layers were identified, from the surface to 180 m and from 300 to 600 m, during daytime. Both layers exhibited significant increases in backscatter near features. Close to features, the shallow layer backscatter was ca. 100 times higher and was driven partly by increasing numbers of larger individuals, evident as single target echoes. We determine the regional scale of influence of features on pelagic biomass enhancement to be ca. 1.8 km in the Chagos Archipelago, and suggest possible ecological explanations that may support it. Our approach determining the scale of influence of bathymetry should be applied during the process of marine reserve design, in order to improve protection of mid-water fauna associated with topographical features, such as seamounts and coral reefs.PostprintPeer reviewe