Conditional preparation of states containing a definite number of photons

A technique for conditionally creating single- or multimode photon-number states is analyzed using Bayesian theory. We consider the heralded N-photon states created from the photons produced by an unseeded optical parametric amplifier when the heralding detector is the time-multiplexed photon-number-resolving detector recently demonstrated by Fitch, et al. [Phys. Rev. A 68, 043814 (2003).] and simultaneously by Achilles, et al. [Opt. Lett. 28, 2387 (2003).]. We find that even with significant loss in the heralding detector, fields with sub-Poissonian photon-number distributions can be created. We also show that heralded multimode fields created using this technique are more robust against detector loss than are single-mode fields.Comment: 6 pages, 6 figures, reference added, typos corrected, content update

Clues on black hole feedback from simulated and observed X-ray properties of elliptical galaxies

The centers of elliptical galaxies host supermassive black holes that significantly affect the surrounding interstellar medium through feedback resulting from the accretion process. The evolution of this gas and of the nuclear emission during the galaxies' lifetime has been studied recently with high-resolution hydrodynamical simulations. These included gas cooling and heating specific for an average AGN spectral energy distribution, a radiative efficiency declining at low mass accretion rates, and mechanical coupling between the hot gas and AGN winds. Here we present a short summary of the observational properties resulting from the simulations, focussing on 1) the nuclear luminosity; 2) the global luminosity and temperature of the hot gas; 3) its temperature profile and X-ray brightness profile. These properties are compared with those of galaxies of the local universe, pointing out the successes of the adopted feedback and the needs for new input in the simulations.Comment: 15 pages, 6 figures, accepted for publication in Advances in Space Researc

On The Use Of Polyurethane Matrix Carbon Fiber Composites For Strengthening Concrete Structures

Fiber-reinforced polymer (FRP) composite materials have effectively been used in numerous reinforced concrete civil infrastructure strengthening projects. Although a significant body of knowledge has been established for epoxy matrix carbon FRPs and epoxy adhesives, there is still a need to investigate other matrices and adhesive types. One such matrix/adhesive type yet to be heavily researched for infrastructure application is polyurethane. This thesis investigates use of polyurethane matrix carbon fiber composites for strengthening reinforced concrete civil infrastructure. Investigations on mirco- and macro-mechanical composite performance, strengthened member flexural performance, and bond durability under environmental conditioning will be presented. Results indicate that polyurethane carbon composites could potentially be a viable option for strengthening concrete structures

EMFF Offshore Reef Survey, Sensitive Ecosystem Assessment and ROV Exploration of Reef - SeaRover 2018 Cruise Report

This report presents preliminary findings of a 2018 offshore reef survey of Ireland’s Northwest continental margin and Rockall Bank. The survey is part of an extensive three year project, beginning 2017, that is coordinated and led by Ireland’s Marine Institute and INFOMAR (Integrated Mapping for the Sustainable Development of Ireland’s Marine Resources) and funded by the European Maritime and Fisheries Fund (EMFF) Marine Biodiversity Scheme and the National Parks and Wildlife Service (NPWS). The objectives of the project are to implement the EMFF’s Marine Biodiversity Scheme - Natura Fisheries by mapping offshore reef habitats with a view to protecting them from deterioration due to fishing pressures. The reef project aligns with sub-article 6.2 of the Habitats Directive (EC 92/43/EEC) which requires member states to take measures to avoid deterioration of protected habitats. The overarching aim is to quantify the abundance and distribution of offshore biogenic and geogenic reef habitat in Irish waters to fulfil Ireland’s legal mandate and to generate baseline data from which appropriate monitoring of Reef habitat within Special Areas of Conservation (SAC) can be established. The initial survey in July 2017 (O’Sullivan et al. 2017) primarily focussed on the Continental margin west and northwest of Ireland. The second survey leg took place in July 2018 aboard the ILV Granuaile. The survey vessel was equipped with the Marine Institute’s remotely operated vehicle (ROV) Holland 1 to observe seabed features and biological associations along the northwest continental shelf and the eastern flank of the Rockall Ban

Systematic Errors in Cosmic Microwave Background Interferometry

Cosmic microwave background (CMB) polarization observations will require superb control of systematic errors in order to achieve their full scientific potential, particularly in the case of attempts to detect the B modes that may provide a window on inflation. Interferometry may be a promising way to achieve these goals. This paper presents a formalism for characterizing the effects of a variety of systematic errors on interferometric CMB polarization observations, with particular emphasis on estimates of the B-mode power spectrum. The most severe errors are those that couple the temperature anisotropy signal to polarization; such errors include cross-talk within detectors, misalignment of polarizers, and cross-polarization. In a B mode experiment, the next most serious category of errors are those that mix E and B modes, such as gain fluctuations, pointing errors, and beam shape errors. The paper also indicates which sources of error may cause circular polarization (e.g., from foregrounds) to contaminate the cosmologically interesting linear polarization channels, and conversely whether monitoring of the circular polarization channels may yield useful information about the errors themselves. For all the sources of error considered, estimates of the level of control that will be required for both E and B mode experiments are provided. Both experiments that interfere linear polarizations and those that interfere circular polarizations are considered. The fact that circular experiments simultaneously measure both linear polarization Stokes parameters in each baseline mitigates some sources of error.Comment: 19 pages, 9 figures, submitted to Phys. Rev.

Multi-frequency polarization properties of ten quasars on deca-parsec scales at z > 3

Global VLBI (EVN+VLBA) polarization observations at 5 and 8.4 GHz of ten high redshift (z > 3) quasars are presented. The core and jet brightness temperatures are found through modelling the self-calibrated uv-data with Gaussian components, which provide reliable estimates of the flux density and size of individual components. The observed high core brightness temperatures (median $T_{\rm b,\,core}=4\times10^{11}$ K) are consistent with Doppler boosted emission from a relativistic jet orientated close to the line-of-sight. This can also explain the dramatic jet bends observed for some of our sources since small intrinsic bends can be significantly amplified due to projection effects in a highly beamed relativistic jet. We also model-fit the polarized emission and, by taking the minimum angle separation between the model-fitted polarization angles at 5 and 8.4 GHz, we calculate the minimum inferred Faraday rotation measure (RM$_{\rm min}$) for each component. We also calculate the minimum intrinsic RM in the rest frame of the AGN (RM$_{\rm min}^{\rm intr}$ = RM$_{\rm min} (1+z)^2$), first subtracting the integrated (presumed foreground) RM in those cases where we felt we could do this reliably. The resulting mean core $|$RM$_{\rm min}^{\rm intr}|$ is 5580 rad m$^{-2}$, with a standard deviation of 3390 rad m$^{-2}$, for four high-z quasars for which we believe we could reliably remove the foreground RM. We find relatively steep core and jet spectral index values, with a median core spectral index of -0.3 and a median jet spectral index of -1.0. Comparing our results with RM observations of more nearby Active Galactic Nuclei at similar emitted frequencies does not provide any significant evidence for dependence of the quasar nuclear environment with redshift.Comment: Published in MNRAS. 18 pages, 7 figures, 5 table

Barriers to healthcare and a ‘triple empathy problem’ may lead to adverse outcomes for autistic adults: A qualitative study

Autistic people experience more co-occurring health conditions and, on average, die younger than non-autistic people. Despite growing awareness of health inequities, autistic people still report barriers to accessing healthcare. We aimed to explore the experiences of autistic people accessing healthcare, shining a light on the complex interplay of relevant factors and to explain, at least in part, the possible reasons underling health disparities and adverse health outcomes. This is a qualitative study from an autistic research team. Data were collected from 1248 autistic adults as part of a large, mixed-methods, international survey exploring barriers to primary healthcare. This article reports the qualitative findings, following a thematic analysis. Using our exploratory findings, we then constructed a model to explain the reported experiences. Respondents reported a variety of barriers. Here, our article gives voice to their stories, in their own words. Themes included: early barriers; communication mismatch; doubt – in oneself and from doctors; helplessness and fear; and healthcare avoidance and serious adverse health outcomes. Our constructed model outlines a chronological journey through which healthcare access barriers may lead to adverse health outcomes. Our findings also build on the double empathy problem, situating this in a medical context, proposing a triple empathy problem

Development of a Human Activity Recognition System for Ballet Tasks

Background: Accurate and detailed measurement of a dancer’s training volume is a key requirement to understanding the relationship between a dancer’s pain and training volume. Currently, no system capable of quantifying a dancer’s training volume, with respect to specific movement activities, exists. The application of machine learning models to wearable sensor data for human activity recognition in sport has previously been applied to cricket, tennis and rugby. Thus, the purpose of this study was to develop a human activity recognition system using wearable sensor data to accurately identify key ballet movements (jumping and lifting the leg). Our primary objective was to determine if machine learning can accurately identify key ballet movements during dance training. The secondary objective was to determine the influence of the location and number of sensors on accuracy. Results: Convolutional neural networks were applied to develop two models for every combination of six sensors (6, 5, 4, 3, etc.) with and without the inclusion of transition movements. At the first level of classification, including data from all sensors, without transitions, the model performed with 97.8% accuracy. The degree of accuracy reduced at the second (83.0%) and third (75.1%) levels of classification. The degree of accuracy reduced with inclusion of transitions, reduction in the number of sensors and various sensor combinations. Conclusion: The models developed were robust enough to identify jumping and leg lifting tasks in real-world exposures in dancers. The system provides a novel method for measuring dancer training volume through quantification of specific movement tasks. Such a system can be used to further understand the relationship between dancers’ pain and training volume and for athlete monitoring systems. Further, this provides a proof of concept which can be easily translated to other lower limb dominant sporting activitie

Understanding the impact of bioactive coating materials for human mesenchymal stromal cells and implications for manufacturing

Bioactive materials interact with cells and modulate their characteristics which enable the generation of cell-based products with desired specifications. However, their evaluation and impact are often overlooked when establishing a cell therapy manufacturing process. In this study, we investigated the role of different surfaces for tissue culture including, untreated polystyrene surface, uncoated Cyclic Olefin Polymer (COP) and COP coated with collagen and recombinant fibronectin. It was observed that human mesenchymal stromal cells (hMSCs) expanded on COP-coated plates with different bioactive materials resulted in improved cell growth kinetics compared to traditional polystyrene plates and non-coated COP plates. The doubling time obtained was 2.78 and 3.02 days for hMSC seeded in COP plates coated with collagen type I and recombinant fibronectin respectively, and 4.64 days for cells plated in standard polystyrene treated plates. Metabolite analysis reinforced the findings of the growth kinetic studies, specifically that cells cultured on COP plates coated with collagen I and fibronectin exhibited improved growth as evidenced by a higher lactate production rate (9.38 × 105 and 9.67 × 105 pmol/cell/day, respectively) compared to cells from the polystyrene group (5.86 × 105 pmol/cell/day). This study demonstrated that COP is an effective alternative to polystyrene-treated plates when coated with bioactive materials such as collagen and fibronectin, however COP-treated plates without additional coatings were found not to be sufficient to support cell growth. These findings demonstrate the key role biomaterials play in the cell manufacturing process and the importance of optimising this selection