An extension of Chaitin's halting probability \Omega to a measurement operator in an infinite dimensional quantum system

This paper proposes an extension of Chaitin's halting probability \Omega to a measurement operator in an infinite dimensional quantum system. Chaitin's \Omega is defined as the probability that the universal self-delimiting Turing machine U halts, and plays a central role in the development of algorithmic information theory. In the theory, there are two equivalent ways to define the program-size complexity H(s) of a given finite binary string s. In the standard way, H(s) is defined as the length of the shortest input string for U to output s. In the other way, the so-called universal probability m is introduced first, and then H(s) is defined as -log_2 m(s) without reference to the concept of program-size. Mathematically, the statistics of outcomes in a quantum measurement are described by a positive operator-valued measure (POVM) in the most general setting. Based on the theory of computability structures on a Banach space developed by Pour-El and Richards, we extend the universal probability to an analogue of POVM in an infinite dimensional quantum system, called a universal semi-POVM. We also give another characterization of Chaitin's \Omega numbers by universal probabilities. Then, based on this characterization, we propose to define an extension of \Omega as a sum of the POVM elements of a universal semi-POVM. The validity of this definition is discussed. In what follows, we introduce an operator version \hat{H}(s) of H(s) in a Hilbert space of infinite dimension using a universal semi-POVM, and study its properties.Comment: 24 pages, LaTeX2e, no figures, accepted for publication in Mathematical Logic Quarterly: The title was slightly changed and a section on an operator-valued algorithmic information theory was adde

Student perceptions of a healthy university

As complex environments within which individuals and populations operate, universities present important contexts for understanding and addressing health issues. The healthy university is an example of the settings approach, which adopts a whole system perspective, aiming to make places within which people, learn, live, work and play supportive to health and wellbeing. The UK Healthy Universities Network has formulated an online toolkit, which includes a self-review tool, intended to enable universities to assess what actions they need to take to develop as a healthy university. This paper presents findings from consultative research undertaken with students from universities in England, Scotland and Wales, which explored what they believe represents a healthy university. Methods Student surveys and focus groups were used to collect data across eleven universities in England, Scotland and Wales. A priori themes were used to develop our own model for a healthy university, and for the thematic coding phase of analysis. Findings A healthy university would promote student health and wellbeing in every aspect of its business from its facilities and environment through to its curriculum. Access to reasonably priced healthy food and exercise facilities were key features of a healthy university for students in this study. The Self Review Tool has provided a crucial start for universities undertaking the journey towards becoming a healthy university. In looking to the future both universities and the UK Healthy Universities Network will now need to look at what students want from their whole university experience, and consider how the Self Review Tool can help universities embrace a more explicit conceptual framework. Conclusion The concept of a healthy university that can tailor its facilities and supportive environments to the needs of its students will go some way to developing students who are active global citizens and who are more likely to value and prioritise health and wellbeing, in the short and long term through to their adult lives

Effect of melt conditioning on heat treatment and mechanical properties of AZ31 alloy strips produced by twin roll casting

In the present investigation, magnesium strips were produced by twin roll casting (TRC) and melt conditioned twin roll casting (MC-TRC) processes. Detailed optical microscopy studies were carried out on as-cast and homogenized TRC and MC-TRC strips. The results showed uniform, fine and equiaxed grain structure was observed for MC-TRC samples in as-cast condition. Whereas, coarse columnar grains with centreline segregation were observed in the case of as-cast TRC samples. The solidification mechanisms for TRC and MC-TRC have been found completely divergent. The homogenized TRC and MC-TRC samples were subjected to tensile test at elevated temperature (250-400 °C). At 250 °C, MC-TRC sample showed significant improvement in strength and ductility. However, at higher temperatures the tensile properties were almost comparable, despite of TRC samples having larger grains compared to MC-TRC samples. The mechanism of deformation has been explained by detailed fractures surface and sub-surface analysis carried out by scanning electron and optical microscopy. Homogenized MC-TRC samples were formed (hot stamping) into engineering component without any trace of crack on its surface. Whereas, TRC samples cracked in several places during hot stamping process.EPSRC – LiME, UK and Towards Affordable, Closed-Loop Recyclable Future Low Carbon Vehicle Structures – TARF-LCV(EP/I038616/1), Department of Mechanical Engineering, Imperial College London, UK, Mr. Steve Cook, Mr. Peter Lloyd, Mr. Graham Mitchell and Mr. Carmelo and BCAST, Brunel University London

Resolvent of Large Random Graphs

We analyze the convergence of the spectrum of large random graphs to the spectrum of a limit infinite graph. We apply these results to graphs converging locally to trees and derive a new formula for the Stieljes transform of the spectral measure of such graphs. We illustrate our results on the uniform regular graphs, Erdos-Renyi graphs and preferential attachment graphs. We sketch examples of application for weighted graphs, bipartite graphs and the uniform spanning tree of n vertices.Comment: 21 pages, 1 figur

Parameter extraction for a superconducting thermal switch (hTron) SPICE model

Efficiently simulating large circuits is crucial for the broader use of superconducting nanowire-based electronics. However, current simulation tools for this technology are not adapted to the scaling of circuit size and complexity. We focus on the multilayered heater-nanocryotron (hTron), a promising superconducting nanowire-based switch used in applications such as superconducting nanowire single-photon detector (SNSPD) readout. Previously, the hTron was modeled using traditional finite-element methods (FEM), which fall short in simulating systems at a larger scale. An empirical-based method would be better adapted to this task, enhancing both simulation speed and agreement with experimental data. In this work, we perform switching current and activation delay measurements on 17 hTron devices. We then develop a method for extracting physical fitting parameters used to characterize the devices. We build a SPICE behavioral model that reproduces the static and transient device behavior using these parameters, and validate it by comparing its performance to the model developed in a prior work, showing an improvement in simulation time by several orders of magnitude. Our model provides circuit designers with a tool to help understand the hTron's behavior during all design stages, thus promoting broader use of the hTron across various new areas of application.Comment: Supplementary material (LTspice schematics and symbol) available on GitHub: https://github.com/vkaram/hTron-behavioral-mode

Augmenting Public Deliberations through Stream Argument Analytics and Visualisations

Public deliberations are organised by governments and other large institutions to take the views of citizens around controversial issues. Increasing public demand and the associated burden on public funding make the quality of public deliberation events and their outcomes critical to modern democracies. This paper focuses on technology developed around streams of computational argument data intended to inform and improve deliberative communication in real time. Combining state-of-the-art speech recognition, argument mining, and analytics, we produce dynamic, interactive visualisations intended for non-experts, deployed incrementally in real time to deliberation participants via large screens, hand-held and personal computing devices. The goal is to bridge the gap between theoretical criteria on deliberation quality from the political sciences and objective analytics calculated automatically from computable argument data in actual public deliberations, presented as a set of visualisations which work on stream data and are simple, yet informative enough to make a positive impact on deliberative outcomes

ADD-up:Visual analytics for augmented deliberative democracy

We demonstrate the first prototype of the ADD-up visual analytics system. The Augmented Deliberative Democracy (ADD-up) project aims to enhance public deliberations by providing argument analytics in real time. The system will ultimately take a stenographic feed of a public deliberation meeting, automatically extract the arguments therein and project visual analytics intended to improve the deliberative quality of the event.publishe

Response of the Hepatic Transcriptome to Aflatoxin B1 in Domestic Turkey (Meleagris gallopavo)

Dietary exposure to aflatoxin B1 (AFB1) is detrimental to avian health and leads to major economic losses for the poultry industry. AFB1 is especially hepatotoxic in domestic turkeys (Meleagris gallopavo), since these birds are unable to detoxify AFB1 by glutathione-conjugation. The impacts of AFB1 on the turkey hepatic transcriptome and the potential protection from pretreatment with a Lactobacillus-based probiotic mixture were investigated through RNA-sequencing. Animals were divided into four treatment groups and RNA was subsequently recovered from liver samples. Four pooled RNA-seq libraries were sequenced to produce over 322 M reads totaling 13.8 Gb of sequence. Approximately 170,000 predicted transcripts were de novo assembled, of which 803 had significant differential expression in at least one pair-wise comparison between treatment groups. Functional analysis linked many of the transcripts significantly affected by AFB1 exposure to cancer, apoptosis, the cell cycle or lipid regulation. Most notable were transcripts from the genes encoding E3 ubiquitin-protein ligase Mdm2, osteopontin, S-adenosylmethionine synthase isoform type-2, and lipoprotein lipase. Expression was modulated by the probiotics, but treatment did not completely mitigate the effects of AFB1. Genes identified through transcriptome analysis provide candidates for further study of AFB1 toxicity and targets for efforts to improve the health of domestic turkeys exposed to AFB1.published_or_final_versio

The effects of baryon physics, black holes and AGN feedback on the mass distribution in clusters of galaxies

The spatial distribution of matter in clusters of galaxies is mainly determined by the dominant dark matter component, however, physical processes involving baryonic matter are able to modify it significantly. We analyse a set of 500 pc resolution cosmological simulations of a cluster of galaxies with mass comparable to Virgo, performed with the AMR code RAMSES. We compare the mass density profiles of the dark, stellar and gaseous matter components of the cluster that result from different assumptions for the subgrid baryonic physics and galaxy formation processes. First, the prediction of a gravity only N-body simulation is compared to that of a hydrodynamical simulation with standard galaxy formation recipes, then all results are compared to a hydrodynamical simulation which includes thermal AGN feedback from Super Massive Black Holes (SMBH). We find the usual effects of overcooling and adiabatic contraction in the run with standard galaxy formation physics, but very different results are found when implementing SMBHs and AGN feedback. Star formation is strongly quenched, producing lower stellar densities throughout the cluster, and much less cold gas is available for star formation at low redshifts. At redshift z = 0 we find a flat density core of radius 10 kpc in both of the dark and stellar matter density profiles. We specu- late on the possible formation mechanisms able to produce such cores and we conclude that they can be produced through the coupling of different processes: (I) dynamical friction from the decay of black hole orbits during galaxy mergers; (II) AGN driven gas outflows producing fluctuations of the gravitational potential causing the removal of collisionless matter from the central region of the cluster; (III) adiabatic expansion in response to the slow expulsion of gas from the central region of the cluster during the quiescent mode of AGN activity.Comment: Published on MNRAS - 13 pages, 4 tables, 9 figure

On topological relaxations of chromatic conjectures

There are several famous unsolved conjectures about the chromatic number that were relaxed and already proven to hold for the fractional chromatic number. We discuss similar relaxations for the topological lower bound(s) of the chromatic number. In particular, we prove that such a relaxed version is true for the Behzad-Vizing conjecture and also discuss the conjectures of Hedetniemi and of Hadwiger from this point of view. For the latter, a similar statement was already proven in an earlier paper of the first author with G. Tardos, our main concern here is that the so-called odd Hadwiger conjecture looks much more difficult in this respect. We prove that the statement of the odd Hadwiger conjecture holds for large enough Kneser graphs and Schrijver graphs of any fixed chromatic number