Physical Sciences and Mathematics Commons^™

Daemon Decay And Inflation, Emil Prodanov

Articles

In 1971, Hawking suggested [1] that there may be a very large number of gravitationally collapsed charged objects of very low masses, formed as a result of fluctuations in the early Universe. A mass of of these objects could be accumulated at the centre of a star like the Sun. The masses of these collapsed objects are from and above and their charges are up to ±30 electron units [1].

One-Pot Synthesis Of Anionic (Nitrogen) And Cationic (Sulfur) Codoped High-Temperature Stable, Visible Light Active, Anatase Photocatalysts, Suresh Pillai, Declan Mccormack, Steven Hinder, Pradeepan Periyat

Articles

No abstract provided.

An Enhanced Data Mining Life Cycle, Markus Hofmann, Brendan Tierney

Conference papers

Data mining projects are complex and can have a high failure rate. In order to improve project management and success rates of such projects a life cycle is vital to the overall success of the project. This paper reports on a research project that was concerned with the life cycle development for data mining projects, its team members and their role. The paper provides a detailed view of the design and development of the data mining life cycle called DMLC. The life cycle aims to support all members of data mining project teams as well as IT managers and academic …

A Phenomenographic Study Of Introductory Physics Students: Approaches To Problem Solving And Conceptualisation Of Knowledge., Laura Walsh

Doctoral

This phenomenographic study presents a description of the approaches to problem solving and conceptualisation of physics knowledge of introductory physics students, specifically in the context of the Irish higher education system. Much research has been carried out that has shown that physics students are not developing the conceptual knowledge necessary to become adept problem-solvers. This may be due to the traditional physics education assumption that students will develop an understanding of the conceptual nature of physics by repetitively solving quantitative problems. However, research has shown that this is not the case and that education and the curriculum needs to explicitly …

Holographic Liquid Crystal Devices, Kotakonda Pavani

Doctoral

Liquid crystals have become natural candidates for use in electro-optic devices for their ability to change the orientation of the director with the application of an electric field, and exhibiting large range of refractive index. The aim of the work presented in this thesis is to fabricate liquid crystal optoelectronic devices such as electrically switchable liquid crystal diffraction gratings and polarization rotators by exploiting the holographic surface relief effect in photopolymer and by developing novel polymer dispersed liquid crystals (PDLCs). Alignment of liquid crystals is commercially achieved by creating grooves on a conducting layer such as polyimide or indium tin …

Three-Dimensional Spatial Information Systems: State Of The Art Review, Bianca Schoen-Phelan, D. Laefer, S. W. Morrish, M. Bertolotto

Articles

A spatial information system (SIS) is critical to the hosting, querying, and analyzing of spatial data sets. The increasing availability of three-dimensional (3D) data (e.g. from aerial and terrestrial laser scanning) and the desire to use such data in large geo-spatial platforms have been dual drivers in the evolution of integrated SISs. Within this context, recent patents demonstrate efforts to handle large data sets, especially complex point clouds. While the development of feature-rich geo-systems has been well documented, the implementation of support for 3D capabilities is only now being addressed. This paper documents the underlying technologies implemented for the support …

Simple Versatile Shearing Interferometer Suitable For Measurements On A Microscopic Scale, Emilia Mihaylova, Vincent Toal

Articles

Microelectromechanical systems (MEMS) behave differently from massive samples. Conventional testing and inspection techniques usually fail at the microscale. Recently there has been an increasing interest in the application of optical techniques for microstructure testing, because they are high-resolution, non-contact, full-field, fast and relatively inexpensive. New interferometric systems, which are suitable for microscopic optical metrology, are of interest for engineering and industrial applications. A modified electronic speckle pattern shearing interferometer (ESPSI) with a very simple shearing device has been designed for metrology applications on the microscale. The shearing device consists of two partially reflective glass plates. The reflection coefficients of the …

Development And Evaluation Of A Novel Automated Physchophysical Instrument For The Investigation Of Nyctalopia Using Multiple Stimulus Light Emitting Diode Matrix Display Arrays., David M.C. O'Brien

Doctoral

Vitamin A deficiency primarily affects young children in developing countries, the symptoms of which initially present as nyctalopia, an inability of the eyes of ‘see’ in low luminance levels, specifically at twilight or at night. Vitamin A deficiency is a major cause of blindness in developing countries and is associated with significant increases in child morbidity and mortality. Nyctalopia may be examined using dark adaptometry; however, current methods of dark adaptometry have many practical limitations, including their unsuitability for use with children. This thesis reports on the design, construction, testing and evaluation of a novel automated dark adaptometer for use …

Spectroscopic Study Of The Dimerisation Process Of Iron Protoporphyrin Ix, K. Dziedzic-Kocurek, Hugh Byrne, A. Swiderski, J. Stanek

Articles

The commercial protoporphyrin IX, iron-ferriprotoporphyrin IX-chloride and synthesized iron porphyrin μ-oxo-dimers were examined by UV/vis absorption and fluorescence, Fourier transformed infrared spectroscopy, resonance Raman, X-ray absorption, Mössbauer spectroscopy and SQUID. The evidence of Fe-O-Fe antiferromagnetic coupling concluded from SQUID and Mössbauer in the case of samples containing dimerized forms confirmed the presence of the oxo-bridges. In this paper the results of UV/vis, fluorescence, Fourier transform infrared FTIR and Raman spectroscopies are reported and discussed. The study is based on the comparison of the free-base protoporphyrin IX, Fe-PPIX-Cl and the synthesized dimerized specimen. The vibrational modes in two energy regions i.e. …

Development Of A Novel Humidity Sensor Based On A Polymer Silver Nanoparticle Composite, Aoife Power, John Cassidy, Tony Betts

Conference Papers

Humidity sensing is of particular concern for many industrial applications. Humidity sensors have typically been based on a reversible interaction between a polymer and water vapour. There is work published on gas sensors based on polymer gold nanoparticle composites, where the conductivity of the composite decreases on interaction with the gas. This happens because the swelling of the polymer which increases the electron hopping distance between the gold nanoparticles. The device in this work is a poly vinyl alcohol silver nanoparticle composite cast on an interdigital electrode array. On application of a dc bias, a current develops which is proportional …

Folate-Cyclodextrin Conjugate For Targeted Chemotherapy, Zlata Tofzikovskaya, Orla L. Howe, Mary Mcnamara, Christine O'Connor

Conference Papers

A general disadvantage of chemotherapy is that the drugs cannot discriminate between fast-growing cancer cells and normal healthy cells which causes many side-effects such as hair loss. An ideal solution to current methods of chemotherapy would be the development of a carrier for an anticancer drug which would be able to transport the drug and therefore target only cancer cells and release the drug molecules inside the cells. In this work folic acid (FA) is attached to an aminoalkane derivative of b-cyclodextrin (CDEn) with a view to developing novel drug delivery systems for therapeutic purposes. Cytotoxisity of folate-conjugate (CDEnFA) is …

On The Socles Of Characteristic Subgroups Of Abelian P-Groups, P. V. Danchev, Brendan Goldsmith

Articles

Fully invariant subgroups of an Abelian p-group have been the object of a good deal of study, while characteristic subgroups have received somewhat less attention. Recently the socles of fully invariant subgroups have been studied and this led to the notion of a socle-regular group. The present work replaces the fully invariant subgroups with characteristic ones and leads in a natural way to the notion of a strongly socle-regular group. A surprising relationship, mirroring that between transitive and fully transitive groups, is obtained.

Quantitative Analyses Of Dispersion, Doping And Electronic Separation Of Single Wall Hipco Carbon Nanotubes, Priya Baskar Rao

Doctoral

As prepared SWNTs are obtained in bundles with a mixture of both metallic and semi conducting tubes. For many specific applications, electronically separated single individual tubes are required and in order to reach these application criteria, the tubes should be processed. This thesis reports on a systematic exploration of methods to routinely process, electronically separate and characterise commercially available single walled carbon nanotubes (SWNTs). Commercially available HiPco SWNTs were dispersed in water with the assistance of 1 % by weight sodium dodecyl benzene sulphate (SDBS). The tubes were dispersed in the water surfactant system through the aid of sonication and …

Enhanced Absorption Metal Oxides For Photocatalytic Applications, Reenamole Georgekutty

Doctoral

Environmental pollution and industrialization on a global scale has drawn attention to the vital need for developing new hygienic and environmentally friendly purification technologies. The most common indoor and outdoor purification process have their corresponding limitations of electricity and/or other energy sources. To address such enormous tasks, advance oxidation technology like heterogeneous photocatalytic systems via metal oxide semiconductors such as TiO2, ZnO, that are capable to operate effectively and efficiently under UV and visible light must be established. Due to the wide band gap of semiconductors, they are unable to absorb visible light. Hence, numerous research efforts have been done …

The Use Of Raman Spectroscopy In The Characterization Of Single Walled Carbon Nanotubes, Elizabeth Gregan

Doctoral

Carbon nanotubes, long, thin cylinders of carbon are intriguing structures and
have sparked much excitement in recent years. It is clear that understanding the fundamental properties of nanotubes is necessary to get a realisation of the full potential of these materials. Processing and purification on a mass scale will need to be carried out if these materials are to have large scale industrial applications and move beyond the laboratory bench. Highly sensitive, capital intensive equipment such as TEM and AFM, have been used to identify the state and morphology of tube samples as well as their levels of purity, however …

Sentiment Classification Of Reviews Using Sentiwordnet, Bruno Ohana, Brendan Tierney

Conference papers

Sentiment classification concerns the use of automatic methods for predicting the orientation of subjective content on text documents, with applications on a number of areas including recommender and advertising systems, customer intelligence and information retrieval. SentiWordNet is an opinion lexicon derived from the WordNet database where each term is associated with numerical scores indicating positive and negative sentiment information. This research presents the results of applying the SentiWordNet lexical resource to the problem of automatic sentiment classification of film reviews. Our approach comprises counting positive and negative term scores to determine sentiment orientation, and an improvement is presented by building …

Toxicity Assessment Of Single-Walled Carbon Nanotubes, Eva Herzog

Doctoral

The objective of this study was to investigate the potential adverse health effects of occupational exposure to SWCNT dust using various in vitro approaches. Lung epithelium (represented by A549 and NHBE cells) was chosen as target cell model and exposed to minimally processed particle samples under submerse conditions and effects were compared to that of carbon black and crocidolite asbestos exposure. Cytotoxicity studies indicated low acute cytotoxicity of SWCNT. Morphological changes included decreases in microvilli and increased numbers of surfactant storing lamellar bodies and changes in cytoskeleton. Due to interactions of SWCNT and toxicity indicator dyes, the clonogenic assay was …

A Covert Encryption Method For Applications In Electronic Data Interchange, Jonathan Blackledge, Dmitry Dubovitskiy

Articles

A principal weakness of all encryption systems is that the output data can be ‘seen’ to be encrypted. In other words, encrypted data provides a ‘flag’ on the potential value of the information that has been encrypted. In this paper, we provide a new approach to ‘hiding’ encrypted data in a digital image.

In conventional (symmetric) encryption, the plaintext is usually represented as a binary stream and encrypted using an XOR type operation with a binary cipher. The algorithm used is ideally designed to: (i) generate a maximum entropy cipher so that there is no bias with regard to any …

Scattering From A Tenuous Random Medium With Applications In Optics, Jonathan Blackledge

Articles

Mathematical models for the scattering of light (and other radiation) tend to fall into two categories based on a weak field condition (single scattering processes) or a strong field condition (multiple scattering processes). In the latter case, the complexity of deterministic models coupled with available solutions often fail to provide results that are of value to engineering systems (e.g. imaging systems). For this reason, multiple scattering problems are often approached using stochastic modelling methods whose foundations lie in random walk theory where the amplitude and phase of the scattered field are taken to conform to an appropriate statistical process and …

Double-Glazing Interferometry, Vincent Toal, Emilia Mihaylova

Articles

This note describes how white light interference fringes can be seen by observing the Moon through a double-glazed window. White light interferometric fringes are normally observed only in a well-aligned interferometer whose optical path difference is less than the coherence length of the light source, which is approximately one micrometer for white light. Obtaining such fringes in a Michelson interferometer is not a trivial task.1 The interferometer is typically illuminated with a monochromatic source and the path length difference adjusted with a wedge angle between the interferometer mirrors so that five or six vertical fringes are visible, indicating nearly equal …

Optical Properties Of Silica-Mfi Doped Acrylamide-Based Photopolymer, Tzvetanka Babeva, Rosen Todorov, Svetlana Mintova, Temenujka Yovcheva, Izabela Naydenova, Vincent Toal

Articles

The optical properties of acrylamide-based photopolymer doped with pure silica MFI-type zeolites are studied by refractometric and spectrophotometric means. Dynamic Light Scattering and Transmission Electron Microscopy are used for zeolite characterization and laser refractometry and White Light Interferometric profilometry are used for surface characterization of the composites. Refractive indices and absorption coefficients of composites are determined from their transmittance and reflectance spectra. The calculated dispersion curves are further used for deriving the zeolites refractive index and porosity and the latter compared to the values of total pore volume obtained from N2-sorption measurements. The impact of the doping level on the …

Optical And Holographic Characteristics Of Photopolymer Layers, Temenujka Yovcheva, Izabela Naydenova, Ivanka Vlaeva, Suzanne Martin, Vincent Toal, Simeon Sainov

Articles

In the present work the optical and holographic characteristics of acrylamide-based photopolymer layers are studied. For the first time the refractive index change of a liquid acrylamide photopolymer due to exposure at 532 nm is obtained using a critical angle laser micro-refractometer. The 30 mm thick solid photopolymer films are prepared by casting on glass substrates. Bragg holographic gratings with spatial frequencies of 710 mm-1, 1050 mm-1 and 1600 mm-1 are recorded using a diode laser operating at 532 nm wavelength. The diffraction efficiency dependence on the exposure energy is investigated. The obtained results are compared with the Stetson holographic …

Investigation Of The Light Induced Redistribution Of Beta Nanoparticles In An Acrylamide-Based Photopolymer, Elsa Leite, Izabela Naydenova, Nitesh Pandey, Tzvetanka Babeva, G. Majano, Svetlana Mintova

Articles

We report the redistribution of colloidal zeolite Beta nanoparticles during holographic recording in acrylamide-based photopolymers. Using the techniques of confocal Raman spectroscopy and scanning electron microscopy coupled with energy dispersive x-ray analysis (SEM–EDX), we have observed a periodic pattern, whose spacing agrees with the fringe spacing of the recorded holographic diffraction grating. It was estimated that the fraction of nanoparticles redistributed as a result of the holographic recording is 40%. The effect of the nanoparticles on the average refractive index of the nanocomposite layers was studied by UV–visible spectroscopy. It was observed that the addition of zeolite nanoparticles leads to …

Second-Hand Smoke Exposure In Cars And Respiratory Health Effects In Children, Patrick J. Goodman, Z. Kabir, Luke Clancy, P.J. Manning, J. Holohan, S. Keogan

Articles

We examined potential associations of ever asthma, and symptoms of wheeze (past 12 months), hay fever, eczema and bronchitis (cough with phlegm) among school children exposed to second-hand smoke (SHS) in cars, using a modified Irish International Study of Asthma and Allergies in Childhood (ISAAC) protocol. 2,809 children of 13–14 yrs old and who selected randomly from post-primary schools throughout Ireland completed the 2007 ISAAC self-administered questionnaire. Adjusted OR (adjusted for sex, active smoking status of children interviewed and their SHS exposure at home) were estimated for the associations studied, using multivariable logistic regression techniques. Overall, 14.8% (13.9% in young …

Silicone Rubber Passive Samplers For Water Quality Monitoring Of Persistent Organic Pollutants In The Marine Environment, Susan O'Hara

Masters

Polychlorinated Biphenyls (PCBs) and Polyaromatic Hydrocarbons (PAHs) are internationally considered as persistent organic pollutants (POPs) which can be mutagenic, carcinogenic and may accumulate in aquatic organisms and potentially in the human chain. PCBs and PAHs are thus listed as priority pollutants in the Water Framework Directive (WFD) and under the Convention for the protection of the Marine Environment of the North-East Atlantic (Oslo Paris Convention: OSPAR). Currently most marine monitoring programmes involving such compounds rely on the collection and analysis of discrete water/sediment grab samples or on the analysis of filter feeding indicator organisms e.g. mussels. Such measurements can provide …

Holographic Recording In Acrylamide Photopolymers: Thickness Limitations, Mohammad Mahmud, Izabela Naydenova, Nitesh Pandey, Tzvetanka Babeva, Raghavendra Jallapuram, Suzanne Martin, Vincent Toal

Articles

Holographic recording in thick photopolymer layers is important for application in holographic data storage, volume holographic filters and correlators. Here, the characteristics of acrylamidebased photopolymer layers having thickness from 250 μm to 1-mm were studied. For each layer thickness samples with three different values of absorbance were studied. By measuring both the first order diffraction efficiency growth of holographically recorded gratings and studying the diffraction patterns obtained, the influence of scattering on the diffraction efficiency of thick volume holographic gratings was analyzed. It was observed that above a particular thickness and absorbance, the first order diffraction efficiency significantly decreased because …

Out-Of-Plane Vibration Analysis With A Transmission Holographic Optical Element Based Electronic Speckle Pattern Interferometer, Viswanath Bavigadda, Vincent Toal, Raghavendra Jallapuram, Emilia Mihaylova

Conference Papers

A simple electronic speckle pattern interferometer (ESPI) using a transmission holographic optical element (THOE) is presented. The THOE is designed to create a speckled reference beam in the interferometer. It is a transmission hologram of a diffusely transmitting glass plate A specific requirement for the fabrication of the THOEs is for them to be recorded at one wavelength at which the recording material is photosensitive and reconstructed using a near infrared laser diode which can be current modulated for phase shifting purposes. A partially reflective glass plate provides illumination of the object along the normal to its surface, ensuring that …

Holographic Recording In Charged Photopolymerisable Nanocomposites, Temenujka Yovcheva, Ivanka Vlaeva, Simeon Sainov, Izabela Naydenova, Vincent Toal, Svetlana Mintova

Conference Papers

Self – processing photopolymers have a large number of different applications due to their versatile properties as holographic recording materials. A significant effort has been directed towards the development of photopolymers for holographic data storage [1, 2], holographic sensors [3], holographic optical elements [4] and display holograms [5]. The Centre for Industrial and Engineering Optics has been developing acrylamide based photopolymers for the last decade [6-8]. The main parameters requiring improvement in these types of photopolymers are their dynamic range and their mechanical stability during the holographic recording. Recently we have successfully used zeolite nanoparticles as dopants in order to …

Recent And Emerging Applications Of Holographic Photopolymers And Nanocomposites, Izabela Naydenova, Pavani Kotakonda, Raghavendra Jallapuram, Tsvetanka Babeva, Denis Bade, Suzanne Martin, Vincent Toal, Svetlana Mintova

Conference Papers

Sensing applications of holograms may be based on effects such as change in the spacing of the recorded fringes in a holographic diffraction grating in the presence of an analyte so that the direction of the diffracted laser light changes, or, in the case of a white light reflection grating, the wavelength of the diffracted light changes. An example is a reflection grating which swells in the presence of atmospheric moisture to indicate relative humidity by a change is the colour of the diffracted light. These devices make use of the photopolymer’s ability to absorb moisture. In a more versatile …

A Test Battery Approach To The Ecotoxicological Evaluation Of Cadmium And Copper Employing A Battery Of Marine Bioassays, Ailbhe Macken, Michelle Giltrap, Kim Ryall, Barry Foley, Evin Mcgovern, Brendan Mchugh, Maria Davoren

Articles

The main aim of this study was to investigate the sensitivity of the battery to two recognised metal pollutants of the marine environment and rank species sensitivity accordingly.