Physical Sciences and Mathematics Commons^™

Facing The Sun, Frank Prendergast, Muiris O'Sullivan, Ken Williams, Gabriel Cooney

Articles

December 2017 marked 50 years since archaeologist Michael J. O’Kelly first observed the solar illumination of the burial chamber in the Neolithic passage tomb at Newgrange during the period of the winter solstice. O’Kelly subsequently recorded direct sunlight entering Newgrange through the ‘especially contrived slit which lies under the roof-box at the outer end of the passage roof’ on 21 December 1969. The discovery of this historic phenomenon, dating back over 5,000 years, captured the public interest and imagination at that time and ever since. In this major article published in the Winter 2017 edition of Archaeology Ireland (date of …

The Potential Of Raman Spectroscopy In The Diagnosis Of Premalignant Oral Lesions, Ola Ibrahim

Doctoral

Thesis submitted in partial fulfilment for the degree of Doctor of Philosophy (PhD) Technological University Dublin, School of Physics December 2017.

Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Doran

Articles

We present a mode-sum regularization prescription for computing the vacuum polarization of a scalar field in static spherically symmetric black hole spacetimes in even dimensions. This is the first general and systematic approach to regularized vacuum polarization in higher even dimensions, building upon a previous scheme we developed for odd dimensions. Things are more complicated here since the even-dimensional propagator possesses logarithmic singularities which must be regularized. However, in spite of this complication, the regularization parameters can be computed in closed form in arbitrary even dimensions and for arbitrary metric function f(r). As an explicit example of our method, we …

Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Breen

Articles

We present a mode-sum regularization prescription for computing the vacuum polarization of a scalar field in static spherically symmetric black hole spacetimes in even dimensions. This is the first general and systematic approach to regularized vacuum polarization in higher even dimensions, building upon a previous scheme we developed for odd dimensions. Things are more complicated here since the even-dimensional propagator possesses logarithmic singularities which must be regularized. However, in spite of this complication, the regularization parameters can be computed in closed form in arbitrary even dimensions and for arbitrary metric function f(r). As an explicit example of our method, we …

What Is Not Where: The Challenge Of Integrating Spatial Representations Into Deep Learning Architectures, John D. Kelleher, Simon Dobnik

Books/Book chapters

This paper examines to what degree current deep learning architectures for image caption generation capture spatial lan- guage. On the basis of the evaluation of examples of generated captions from the literature we argue that systems capture what objects are in the image data but not where these objects are located: the cap- tions generated by these systems are the output of a language model conditioned on the output of an object detector that cannot capture fine-grained location information. Although language models provide useful knowledge for image captions, we argue that deep learning image captioning architectures should also model geometric …

Modular Mechanistic Networks: On Bridging Mechanistic And Phenomenological Models With Deep Neural Networks In Natural Language Processing, Simon Dobnik, John D. Kelleher

Books/Book chapters

Natural language processing (NLP) can be done using either top-down (theory driven) and bottom-up (data driven) approaches, which we call mechanistic and phenomenological respectively. The approaches are frequently considered to stand in opposition to each other. Examining some recent approaches in deep learning we argue that deep neural networks incorporate both perspectives and, furthermore, that leveraging this aspect of deep learning may help in solving complex problems within language technology, such as modelling language and perception in the domain of spatial cognition.

On Demonstrating The Impact Of Defeasible Reasoning Via A Multi-Layer Argument-Based Framework (Doctoral Consortium), Lucas Middeldorf Rizzo

Conference papers

Promising results have indicated Argumentation Theory as a solid research area for implementing defeasible reasoning in practice. However, applications are usually domain dependent, not incorporating all the layers and steps required in an argumentation process, thus limit- ing their applicability in different areas. This PhD project is focused on the development of a multi-layer defeasible argument-based framework which is in turn used across different applications in the fields of decision making and knowledge representation and reasoning. The inference produced is compared against the inference of different quantitative theories of reasoning under uncertainty such as expert systems and fuzzy logic. The …

A Mathematical Analysis Of Drug Dissolution In The Usp Flow Through Apparatus, David Mcdonnell, Deirdre M. D'Arcy, Lawrence J. Crane, Brendan Redmond

Articles

This paper applies boundary layer theory to the process of drug dissolution in the USP (United States Pharmacopeia) Flow Through Apparatus. The mass transfer rate from the vertical planar surface of a compact within the device is examined. The theoretical results obtained are then compared with those of experiment. The paper also examines the effect on the dissolution process caused by the interaction between natural and forced convection within the apparatus and the introduction of additional boundaries.

The Evaluation Of The Effect Of Strain Limits On The Physical Properties Of Magnetorheological Elastomers Subjected To Uniaxial And Biaxial Cyclic Testing., Dave Gorman, Niall Murphy, Ray Ekins, Stephen Jerrams

Articles

Magnetorheological Elastomers (MREs) are “smart” materials whose physical properties are altered by the application of magnetic fields. In a previous study by the authors [1], variations in the physical properties of MREs have been evaluated when subjected to a range of magnetic field strengths for both uniaxial and biaxial cyclic tests. By applying the same magnetic field to similar samples, this paper investigates the effect of both the upper strain limit and the strain amplitude on the properties of MREs subjected to cyclic fatigue testing. As the magnetorheological (MR) effect is due to the dipole-dipole interactions of the …

Streaming Vr For Immersion: Quality Aspects Of Compressed Spatial Audio, Miroslaw Narbutt, Sean O’Leary, Andrew Allen, Jan Skoglund, Andrew Hines

Conference papers

Delivering a 360-degree soundscape that matches full sphere visuals is an essential aspect of immersive VR. Ambisonics is a full sphere surround sound technique that takes into account the azimuth and elevation of sound sources, portraying source location above and below as well as around the horizontal plane of the listener. In contrast to channel-based methods, ambisonics representation offers the advantage of being independent of a specific loudspeaker set-up. Streaming ambisonics over networks requires efficient encoding techniques that compress the raw audio content without compromising quality of experience (QoE). This work investigates the effect of audio channel compression via the …

Development Of Sensitive Holographic Devices For Physiological Metal Ion Detection, Sabad-E- Gul, Suzanne Martin, John Cassidy, Izabela Naydenova

Conference Papers

The development of selective alkali metal ions sensors in particular is a subject of significant interest. In this respect, the level of blood electrolytes, particularly H+, Na+, K+ and Cl- , is widely used to monitor aberrant physiologies associated with pulmonary emphysema, acute and chronic renal failure, heart failure, diabetes. The sensors reported in this paper are created by holographic recording of surface relief structures in a self-processing photopolymer material. The structures are functionalized by ionophores dibenzo-18-crown-6 (DC) and tetraethyl 4-tert-butylcalix[4]arene (TBC) in plasticised polyvinyl chloride (PVC) matrix. Interrogation of these structures by light allows indirect measurements of chemical analytes’ …

Rating By Ranking: An Improved Scale For Judgement-Based Labels, Jack O'Neill, Sarah Jane Delany, Brian Mac Namee

Conference papers

Labels representing value judgements are commonly elicited using an interval scale of absolute values. Data collected in such a manner is not always reliable. Psychologists have long recognized a number of biases to which many human raters are prone, and which result in disagreement among raters as to the true gold standard rating of any particular object. We hypothesize that the issues arising from rater bias may be mitigated by treating the data received as an ordered set of preferences rather than a collection of absolute values. We experiment on real-world and artificially generated data, finding that treating label ratings …

A Case Study For Ecampus Spatial: Business Data Exploration, James Carswell, Thanh Thao Pham Ti, Andrea Ballatore, Junjun Yin, Linh Truong-Hong

Books/Book chapters

Location based querying is the core interaction paradigm between mobile citizens and the Internet of Things, so providing users with intelligent web-services that interact efficiently with web and wireless devices to recommend personalised services is a key goal. With today's popular Web Map Services, users can ask for general information at a specific location, but not detailed information such as related functionality or environments. This shortcoming comes from a lack of connection between non-spatial “business” data and spatial “map” data. This chapter presents a novel approach for location-based querying in web and wireless environments, in which non-spatial business data is …

An Analysis Of The Application Of Simplified Silhouette To The Evaluation Of K-Means Clustering Validity, Fei Wang, Hector-Hugo Franco-Penya, John D. Kelleher, John Pugh, Robert J. Ross

Conference papers

Silhouette is one of the most popular and effective internal measures for the evaluation of clustering validity. Simplified Silhouette is a computationally simplified version of Silhouette. However, to date Simplified Silhouette has not been systematically analysed in a specific clustering algorithm. This paper analyses the application of Simplified Silhouette to the evaluation of k-means clustering validity and compares it with the k-means Cost Function and the original Silhouette from both theoretical and empirical perspectives. The theoretical analysis shows that Simplified Silhouette has a mathematical relationship with both the k-means Cost Function and the original Silhouette, while empirically, we show that …

Broadband Acoustic Measurement Of The Agar-Based Tissue Mimicking Material – A Longitudinal Study, Adela Rabell-Montiel, Jacinta Browne, Stephen Pye, Tom Anderson, Carmel Moran

Articles

Commercially available ultrasound quality assurance test phantoms rely upon the long-term acoustic stability of tissue-mimicking-materials (TMMs). The measurement of the acoustic properties can be technically challenging and it is important to ensure its stability. The standard technique is to film-wrap samples of TMM and to measure the acoustic properties in a water bath. In this study, a modified technique is proposed whereby the samples of TMM are measured in a preserving fluid that is intended to maintain their characteristics. The acoustic properties were evaluated using a broadband pulse-echo substitution technique over the frequency range of 4.5 – 50 MHz at …

Formulation, Characterisation And Stability Assessment Of A Food Derived 1 Tripeptide, Leucine-Lysine-Proline Loaded Chitosan Nanoparticles, M.K. Danish, Giuliana Vozza, Hugh Byrne, Jesus Maria Frias, Sinead Ryan

Articles

The chicken or fish derived tripeptide, Leucine-Lysine-Proline (LKP), inhibits the Angiotensin Converting Enzyme and may be used as an alternative treatment for pre-hypertension. However, it has low permeation across the small intestine. The formulation of LKP into a nanoparticle (NP) has the potential to address this issue. LKP-loaded NPs were produced using an ionotropic gelation technique, using chitosan (CL113). Following optimisation of unloaded NPs, a mixture amount design was constructed using variable concentration of CL113 and tripolyphosphate at a fixed LKP concentration. Resultant particle sizes ranged from 120-271 nm, zeta potential values from 29-37 mV and polydispersity values from 0.3-0.6. …

Antifungal Potential Of Copper(Ii), Manganese(Ii) And Silver(I) 1,10-Phenanthroline Chelates Against Multidrug-Resistant Fungal Species Forming The Candida Haemulonii Complex: Impact On The Planktonic And Biofilm Lifestyles, Rafael M. Gandra, Pauraic Mc Carron, Mariana F. Fernandes, Lívia S. Ramos, Thaís P. Mello, Ana Carolina Aor, Marta H. Branquinha, Malachy Mccann, Michael Devereux, André L. S. Santos

Articles

Candida haemulonii, Candida haemulonii var. vulnera and Candida duobushaemulonii, which form the C. haemulonii complex, are emerging etiologic agents of fungal infections known to be resistant to the most commonly used antifungals. The well-established anti-Candida potential ofmetal complexes containing 1,10-phenanthroline (phen) ligands encouraged us to evaluate different copper(II), manganese(II), and silver(I) phen chelates for their ability to inhibit planktonic growth and biofilm of C. haemulonii species complex. Two novel coordination complexes, {[Cu(3,6,9-tdda)(phen)2].3H2O.EtOH}n and [Ag2(3,6,9-tdda)(phen)4].EtOH (3,6,9-tddaH2 = 3,6,9-trioxaundecanedioic acid), were synthesized in a similar fashion to the other, previously documented, sixteen copper(II), manganese(II), and silver(I) chelates employed herein. Three isolates of …

Solid-Phase Peptide Synthesis Of Analogues Of The N-Terminus A-Ring Fragment Of The Lantibiotic Nisin: Replacements For The Dehydroalanine (Dha) Residue At Position 5 And The First Incorporation Of A Thioamide Residue, Kim Manzor, Keith Ó Proinsias, Fintan Kelleher

Articles

A number of A-ring analogues of the lantibiotic nisin, containing replacements for the Dha at position 5, have been successfully prepared by solid-phase peptide synthesis. The Dha replacements include glycine, alanine, phenylalanine, serine and 1-aminocyclopropyl carboxylic acid (ACCa). The incorporation of a thioamide-isoleucine residue at position 4 is also described and is the first report of the preparation of a lantibiotic ring fragment containing a thioamide link.

Back To The Future: Logic And Machine Learning, Simon Dobnik, John D. Kelleher

Conference papers

In this paper we argue that since the beginning of the natural language processing or computational linguistics there has been a strong connection between logic and machine learning. First of all, there is something logical about language or linguistic about logic. Secondly, we argue that rather than distinguishing between logic and machine learning, a more useful distinction is between top-down approaches and data-driven approaches. Examining some recent approaches in deep learning we argue that they incorporate both properties and this is the reason for their very successful adoption to solve several problems within language technology.

Reflections On An Experiment, Evaluating The Impact Of Spatialisation On Exploration, Clement Roux, John Mcauley

Conference papers

This paper reports on an experiment designed to evaluate whether visualising a digital library (using a spatialisation technique) can influence exploratory search behaviour. In the experiment we asked participants to complete a set of novel tasks using one of two interfaces - a visualisation interface, ExploViz, and its search-based equivalent, LibSearch. A set of measures were used to capture sensemaking and exploratory behaviour and to analyse cognitive load. As results were non-significant, we reflect upon the design of the experiment, consider possible issues and suggest how these could be addressed in future iterations.

Estimation Of Train Driver Workload: Extracting Taskload Measures From On-Train-Data-Recorders, Nora Balfe, Katie Crowley, Brendan Smith, Luca Longo

Conference papers

This paper presents a method to extract train driver taskload from downloads of on-train-data-recorders (OTDR). OTDR are in widespread use for the purposes of condition monitoring of trains, but they may also have applications in operations monitoring and management. Evaluation of train driver workload is one such application. The paper describes the type of data held in OTDR recordings and how they can be transformed into driver actions throughout a journey. Example data from 16 commuter journeys are presented, which highlights the increased taskload during arrival at stations. Finally, the possibilities and limitations of the data are discussed.

Ultra-Filtration Of Human Serum For Improved Quantitative Analysis Of Low Molecular Weight Biomarkers Using Atr-Ir Spectroscopy, Franck Bonnier, Luis Felipe Cs. Carvalho, Matthew J. Baker, Hugh Byrne, Igor Chourpa

Articles

Infrared spectroscopy is a reliable, rapid and cost effective characterisation technique, delivering a molecular finger print of the sample. It is expected that its sensitivity would enable detection of small chemical variations in biological samples associated with disease. ATR-IR is particularly suitable for liquid sample analysis and, although air drying is commonly performed before data collection, just a drop of human serum is enough for screening and early diagnosis. However, the dynamic range of constituent biochemical concentrations in the serum composition remains a limiting factor to the reliability of the technique. Using glucose as a model spike in human serum, …

Extraoral Maxillofacial Prosthesis Implant Retention Systems: A Critical Review., Hugh Byrne, Marina L. Pimentel

Articles

Objectives: The purpose of this literature review is to provide information on the different available techniques for implant-supported prosthetic retention, which are bar-clip, o-ring or magnets. Through presenting the practitioner preferences reported in literature, although limited from strict comparison due to the heterogeneity of methodologies and studied individuals, this review aims to identify the choices for maxillofacial prosthesis implant retention systems, regarding patient comfort and good aesthetic outcome, as an aid to surgical and prosthetic planning for implant-supported extraoral maxillofacial prosthetics. With proper knowledge of each implant retention system, a practitioner can design a treatment plan which allows for a …

Industrial Grade 2d Molybdenum Disulphide (Mos2): An In-Vitro Exploration Of The Impact On Cellular Uptake, Cytotoxicity, And Inflammation, Caroline Moore, Hugh Byrne, Jonathan N. Coleman, Yuri Volkov, Jennifer Mcintyre

Articles

The recent surge in graphene research, since its liquid phase monolayer isolation and characterization in 2004, has led to advancements which are accelerating the exploration of alternative 2D materials such as molybdenum disulphide (MoS2), whose unique physico-chemical properties can be exploited in applications ranging from cutting edge electronic devices to nanomedicine. However, to assess any potential impact on human health and the environment, the need to understand the bio-interaction of MoS2 at a cellular and sub-cellular level is critical. Notably, it is important to assess such potential impacts of materials which are produced by large scale production techniques, rather than …

Conformational Studies Of Gram-Negative Bacterial Quorum Sensing 3-Oxo N-Acyl Homoserine Lactone Molecules, Darren Crowe, Alan Nicholson, Adrienne Fleming, Ed Carey, Goar Sanchez-Sanz, Fintan Kelleher

Articles

In their ¹H NMR spectra in CDCl₃ 3-oxo-N-acyl homoserine lactones (OHLs) show significant downfield chemical shifts of the amide N-H proton when compared to the parent N-acyl homoserine lactones (AHLs). NMR spectroscopic and DFT calculation studies have shown that this is most likely due to the presence of a stabilising intramolecular H-bond from the N-H to the 3-oxo group. The ¹H NMR spectra also show evidence for the enol tautomers and that the amount of enol present for a range of OHLs is 4.1-4.5% in CDCl₃ and 6.5-7.2% in CD₃CN. In …

Tackling The Interleaving Problem In Activity Discovery, Eoin Rogers, Robert J. Ross, John D. Kelleher

Conference papers

Activity discovery (AD) is the unsupervised process of discovering activities in data produced from streaming sensor networks that are recording the actions of human subjects. One major challenge for AD systems is interleaving, the tendency for people to carry out multiple activities at a time a parallel. Following on from our previous work, we continue to investigate AD in interleaved datasets, with a view towards progressing the state-of-the-art for AD.

Motor Preparation Rather Than Decision-Making Differentiates Parkinson’S Disease Patients With And Without Freezing Of Gait, John Butler, Conor Fearon, Isabelle Killane, Saskia M. Waechter, Richard B. Reilly, Timothy Lynch

Articles

Objective: Freezing of gait (FOG) is a brief, episodic phenomenon affecting over half of people with Parkinson’s disease (PD) and leads to significant morbidity. The pathophysiology of FOG remains poorly understood but is associated with deficits in cognitive function and motor preparation.

Method: We studied 20 people with PD (10 with FOG, 10 without FOG) and performed a timed response target detection task while electroencephalographic data were acquired. We analysed the data to detect and examine cortical markers of cognitive decision making (P3b or centroparietal positivity, CPP) and motor readiness potential. We analysed current source density (CSD) to increase spatial …

Strain-Induced Spectral Tuning Of The Whispering Gallery Modes In A Cylindrical Micro-Resonator Formed By A Polymer Optical Fiber, Vishnu Kavungal, Arun Mallik, Gerald Farrell, Qiang Wu, Yuliya Semenova

Articles

A mechanical strain assisted technique for spectral tuning of whispering gallery modes (WGM) in a cylindrical micro-resonator formed by a polymer optical fiber (POF) is investigated. WGMs in the POF based micro-cylinder are excited by evanescent light coupling using a tapered single mode silica fiber. WGMs observed in the transmission spectrum of the silica fiber taper have a high extinction ratio of up to 19 dB and a Q-factor of up to 2.64 × 10⁴. The application of tensile axial strain (μɛ) in the range from 0 to 1746 μɛ (0.17 %) to the POF micro-resonator results in …

Robot Perception Errors And Human Resolution Strategies In Situated Human-Robot Dialogue, Niels Schütte, Brian Mac Namee, John D. Kelleher

Articles

Errors in visual perception may cause problems in situated dialogues. We investigated this problem through an experiment in which human participants interacted through a natural language dialogue interface with a simulated robot.We introduced errors into the robot’s perception, and observed the resulting problems in the dialogues and their resolutions.We then introduced different methods for the user to request information about the robot’s understanding of the environment. We quantify the impact of perception errors on the dialogues, and investigate resolution attempts by users at a structural level and at the level of referring expressions.

An Ionic Liquid Based Sensor For Diclofenac Determination In Water, Emma Brennan, Pauline Futvoie, John Cassidy, Benjamin Schazmann

Articles

This paper details a miniaturised, solid state ion-selective electrode selective for diclofenac. The sensor comprises a novel ionic liquid electroactive material – an imidazolium–diclofenac ion associate. The ion associate is present in a plasticised poly(vinyl chloride) (PVC) membrane on planar carbon electrodes, with an intermediate poly(3,4-ethylenedioxythiophene) layer. The sensitivity and selectivity of the sensor were determined using chronopotentiometric methods. In response to diclofenac, a slope of −53.3 ± 3.6 mV/dec was observed. A limit of detection of 2.90 × 10−3 g L−1 is reported, with a linear range of 3.18 × 10−3 g L−1 to 3.18 g L−1. …