Physical Sciences and Mathematics Commons^™

Search For A Correlation Between Very-High-Energy Gamma Rays And Giant Radio Pulses In The Crab Pulsar, E. Aliu, S. Archambault, T. Arlen, T. Aune, M. Beilicke, W. Benbow, A. Bouvier, J. H. Buckley, V. Bugaev, P. T. Reynolds, Et Al

Physical Sciences Publications

We present the results of a joint observational campaign between the Green Bank radio telescope and the VERITAS gamma-ray telescope, which searched for a correlation between the emission of very-high-energy (VHE) gamma rays (E γ > 150 GeV) and giant radio pulses (GRPs) from the Crab pulsar at 8.9 GHz. A total of 15,366 GRPs were recorded during 11.6 hr of simultaneous observations, which were made across four nights in 2008 December and in 2009 November and December. We searched for an enhancement of the pulsed gamma-ray emission within time windows placed around the arrival time of the GRP events. …

Veritas Observations Of Six Bright, Hard-Spectrum Fermi-Lat Blazars, P. T. Reynolds, Et Al

Physical Sciences Publications

We report on VERITAS very high energy (VHE; E ≥ 100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray absorption by the extragalactic background light into account. This allowed the selection of six bright, hard-spectrum blazars that were good candidate TeV emitters. Spectroscopic redshift measurements were attempted with the Keck Telescope for the targets without Sloan Digital Sky Survey spectroscopic data. No VHE emission is detected during the observations of the six sources described here. Corresponding TeV …

Constraints On Cosmic Rays, Magnetic Fields, And Dark Matter From Gamma-Ray Observations Of The Coma Cluster Of Galaxies With Veritas And Fermi, P. T. Reynolds, Et. Al.

Physical Sciences Publications

Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may also be sources of very high energy (VHE; E > 100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cerenkov telescopes, with complementing Fermi Large Area Telescope observations at GeV energies. No significant gamma-ray emission from the Coma Cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order …

Variability Of The Blazar 4c 38.41 (B3 1633+382) From Ghz Frequencies To Gev Energies, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

Context. After years of modest optical activity, the quasar-type blazar 4C 38.41 (B3 1633+382) experienced a large outburst in 2011, which was detected throughout the entire electromagnetic spectrum, renewing interest in this source.

Aims. We present the results of low-energy multifrequency monitoring by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) consortium and collaborators, as well as those of spectropolarimetric/spectrophotometric monitoring at the Steward Observatory. We also analyse high-energy observations of the Swift and Fermi satellites. This combined study aims to provide insights into the source broad-band emission and variability properties.

Methods. We assemble …

Multiwavelength Observations Of The Agn 1es 0414+009 With Veritas, Fermi-Lat, Swift-Xrt, And Mdm, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between 2008 January and 2011 February, resulting in 56.2 hr of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4σ) above the background. The source flux, showing no evidence for variability, is measured as (5.2 ± 1.1stat ± 2.6sys) × 10–12 photons cm–2 s–1 above 200 GeV, equivalent to approximately 2% of the Crab …

Veritas Observations Of The Nova In V407 Cygni, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 × 10–12 erg cm–2 …

Pump Dependence Of The Dynamics Of Quantum Dot Based Waveguide Absorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.

Physical Sciences Publications

The nonlinear two stage recovery of quantum dot based reverse-biased waveguide absorbers is investigated experimentally and analytically as a function of the initial ground state occupation probability of the dot. The latter is controlled experimentally by the pump pulse power. The slow stage of the recovery is exponential and its basic timescale is independent of pump power. The fast stage of the recovery is a logistic function which we analyze in detail. The relative strength of slow to fast components is highlighted and the importance of higher order absorption processes at the highest pump level is demonstrated.

Discovery Of Tev Gamma-Ray Emission Toward Supernova Remnant Snr G78.2+2.1, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report the discovery of an unidentified, extended source of very-high-energy gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hr of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic …

Discovery Of High-Energy And Very High Energy Gamma-Ray Emission From The Blazar Rbs 0413, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report on the discovery of high-energy (HE; E > 0.1 GeV) and very high energy (VHE; E > 100 GeV) γ-ray emission from the high-frequency-peaked BL Lac object RBS 0413. VERITAS, a ground-based γ-ray observatory, detected VHE γ rays from RBS 0413 with a statistical significance of 5.5 standard deviations (σ) and a γ-ray flux of (1.5 ± 0.6stat ± 0.7syst) × 10–8 photons m–2 s–1 (~1% of the Crab Nebula flux) above 250 GeV. The observed spectrum can be described by a power law with a photon index of 3.18 ± 0.68stat ± 0.30syst. Contemporaneous observations with the Large Area …

Bounded Phase Phenomena In The Optically Injected Laser, Bryan Kelleher, David Goulding, B. Baselga Pascual, Stephen P. Hegarty, Guillaume Huyet

Cappa Publications

Two routes to phase-locking in the optically injected laser system are investigated both involving limit cycles where the phase of the slave laser is unlocked but is nevertheless bounded. We use an experimental phase-resolving technique to unambiguously demonstrate the phenomenon via explicit phasors for the slave laser electric field. Theoretical considerations show that for locking mechanisms involving Hopf bifurcations, such limit cycles of bounded phase are generic. For weakly damped devices, such as quantum well lasers, this can involve an excited resonance at the relaxation oscillation frequency. For highly damped devices there is no such excitation but the bounded phase …

Veritas Observations Of Day-Scale Flaring Of M 87 In 2010 April, P. T. Reynolds, Et. Al.

Physical Sciences Publications

VERITAS has been monitoring the very-high-energy (VHE; > 100 GeV) gamma-ray activity of the radio galaxy M 87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 ± 0.16) × 10–11 cm–2 s–1 at energies above 350 GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 ± 0.68) × 10–11 cm–2 s–1 for E > 350 GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good-quality data. The most rapid flux variation …

The 2010 Very High Energy Gamma-Ray Flare And 10 Years Of Multi-Wavelength Observations Of M 87, P. T. Reynolds, Hess, Magic, Veritas, Et. Al.

Physical Sciences Publications

The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 – 6) × 109 M ☉) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) γ-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE γ-ray emitter since 2006. The VHE γ-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in …

Coulomb-Induced Emission Dynamics And Self-Consistent Calculations Of Type-Ii Sb-Containing Quantum Dot Systems, Kamil Gradkowski, Tomasz J. Ochalski, N. Pavarelli, H. Y. Liu, J. Tatebayashi, D. B. Williams, Guillaume Huyet, D. L. Huffaker

Cappa Publications

This paper investigates the effects of Coulomb interactions on the emission dynamics of Sb-containing quantum dot (QD) systems under high excitation densities. Two different type-II confinements are studied: confined electrons with unconfined holes using InAs/GaAs QDs capped with a GaAsSb quantum well (type-IIa), and confined holes with unconfined electrons using GaSb/GaAs QDs capped with an InGaAs quantum well (type-IIb). Time-resolved photoluminescence experiments are compared with self-consistent numerical calculations using an 8-band k·p model. In both structures, we observe a significant blueshift of emission and wavelength-dependent radiative lifetimes, but with marked quantitative differences between the two systems: in the type-IIa, the …

Investigation Of Factors Influencing Trichloromethane Levels In Milk And Its Control., Siobhan Ryan

Theses

Trichloromethane (TCM) is an undesirable chemical residue that can develop in milk. While TCM levels in milk are not within ranges of public health concern, it is important that minimal levels are maintained in order to promote the marketing of Irish dairy products abroad. Germany has enacted strict regulations on TCM concentrations in foodstuffs with a recommended level of0.002 mg/kg and re-analyse those milks, subsequent to cause identification and provision of advice on reducing TCM levels in milk. Milk samples were analysed using Gas chromatography (GC) with electron capture detection. The GC method was adapted and a standard curve was …

The Identification And Reduction Of Energy Streams Within The Pharmaceutical Sector Using Software Algorithms, Raymond Corbett

Theses

Pharmaceutical companies are under increasing financial pressure to optimise production costs, due to a growing number of products coming off patent, research and development costs increasing exponentially and the difficulty of bringing genuinely innovative products to market. Generic drug manufacturers are not exempt from these pressures; costs must be driven down by all drug manufacturers due to the increasingly competitive healthcare market.

The operating costs of a modern Pharmaceutical Plant run to several Million Euros per annum. Complex process’s involving the consumption of large amounts of energy, and hence costs, are a necessity. Any increase in the efficiency of a …

Characterisation Of Crataegus Monogyna Fractions And Assessment Of Their Functional Properties, Eilish Shortle

Theses

Hawthorn {Crataegus monogyna) is a herb that has been used medicinally since ancient times. In modern medicine it is known for its cardiotonic properties and is used as a cardiovascular protective, hypotensive and hypocholesterolemic agent. In recent years supercritical fluid extraction (SFE) has become more popular as an extraction method for botanical material as it is an environmentally-friendly method that can produce toxic-free extracts. The optimal SFE extraction conditions for the extraction of antioxidant compounds from both, hawthorn leaf & dower and hawthorn berries, using carbon dioxide, were determined in this study. The optimized extracts were then compared to pre-prepared …

The Effects Of Climate On The Growth Of Winter Wheat And Spring Barley In An Irish Context, Adrian Kennedy

Theses

The climate of earth is always changing due to natural events, however it is thought that the rapid warming period currently taking place is primarily due human activity to (environmental protection agency 2012). Climate change is altering the environment and this will have consequences for agriculture (Teagasc publications 2012). In this study we examine the relationship between weather and the yield of winter wheat and spring barley in an Irish context using data gathered from 2004-2010 at the Teagasc Oak Park research centre in Carlow. The data was analysed using a mixed effect model to test which if any weather …

An Investigation Of Discontinuous Specular Surfaces Using Non-Contact Techniques In Line Monitoring., Kiryl Kekukh

Theses

Surface metrology by structured light projection has been a standard technique in industry for many years. However, when the surface under test is reflective or specular it is impossible to use this particular method. In this instance a modified procedure called "Fringe Reflection” is used. In this technique patterns similar to structured light are projected onto a screen, located remotely from the surface, and fringe patterns, reflected via the surface, are recorded using a CCD-camera. To recover the range data of such a surface from a set of images taken, a phase unwrapping algorithm is used. For the purpose and …

Usability Evaluation Of Modeling Languages, Christian Schalles

Theses

Over the last two decades more and more companies started to recognize the importance of graphical modeling as a way to meet their business goals. In order to describe a business case such as a business process or an application system, information in various different formats has to be integrated within a graphical model. Graphical models are developed using modeling languages such as the Unified Modeling Language (UML) and Event Driven Process Chains (EPC). The usability of graphical modeling languages has not been explicitly considered in past research. Most usability evaluation surveys are mainly focusing on applications, websites, software and …

Visualising Urban Flooding Scenarios Using Video Game Technology, William Elliott Lynn

Theses

This thesis investigates the application of computer graphics to the visualisation of urban flooding scenarios. The demand for urban flooding visualisations is presented in the context of an EU wide climate change response strategy. An analysis of the requirements from various stakeholders is presented and a strategy that addresses these requirements is synthesised. A study on the appropriate computer graphics methods and technologies is outlined and limitations of current technologies are assessed. Systems that solve these limitations are described and the result of usability and user acceptance testing are offered as evidence.

Ontology Management For Universities, Roland Böving

Theses

What is the 'knowledge' of a university? It is the sum of all experiences and all contributions of students and staff. Knowledge ultimately exists, among other things, in the form of theses, articles, lectures and research reports. The largest knowledge pool of a university is made up, however, of the knowledge and expertise of every single member of the university. As a result of the high rate of turnover of people, knowledge and expertise are on the one hand constantly being lost, but this is replaced by a fresh intake of upcoming young students and lecturers reflecting the spirit of …

Development Of Mass Spectrometric Methods For The Analysis Of Serotonin And Related Compounds In Biological Matrices, Merisa Moriarty

Theses

Serotonin is a major neurotransmitter in the brain and affects various functions both in the brain and in the rest of the body. It has been linked to depression, migraines, and aggression, as well as many psychiatric disorders including schizophrenia, dementia and anorexia nervosa. It also has been associated with conditions like Alzheimer’s disease along with other neurotransmitters such as dopamine.

The aim of this research project is to develop various mass spectrometric methods for the analysis of serotonin, dopamine and similar indoles in both urine and serum matrices. This thesis provides extensive reviews detailing a general overview of serotonin …

Morality In The Virtual Space: Applying Moral Philosophy To Digital Worlds, James O'Sullivan

Theses

Since the turn of the century and the dawn of the digital age, online communities have witnessed significant growth in their importance. Significant numbers of virtual environments now exist, within which millions of individuals interact socially and economically, engaged fully in what is equivalent to a physical encounter, the only differences being the virtual representations through which they interact, and the physical security that this representation affords them. Though physically absent, individuals are fully engaged psychologically, and thus open to the same ethical dilemmas presented through reality. Application of real-world moral codes is encumbered by the existence of what 1 …

Evaluating The Irish Technical Guidance Documents In The Context Of Sustainability, Rosemarie Macsweeney

Theses

Sustainability is more than just a “buzz word” or meaningless jargon; it is what is needed for survival due to the unsustainability of humanity in recent centuries. Sustainable buildings are only one element of the solution, but a very large one in terms of the amount of problems created socially, economically and environmentally by buildings. Humans now spend more and more time in buildings, most of their days in many cases, and so the regulation and policy mechanisms surrounding buildings are critical to the success of sustainability. The Irish Technical Guidance Documents (TGDs), are a set of twelve documents which …

Dynamics Of Passively Mode-Locked Lasers With Optical Injection, Natalia Rebrova

Theses

Semiconductor passively mode-locked (ML) lasers are of particular interest due to their compactness, cost-efficiency and ease of operation. However, outside optimal parameter range these lasers suffer waveform instabilities, large chirp and significant timing jitter, which makes them ineffective in highspeed applications. In this work we model monolithic passively mode-locked lasers using delay differential equations. We study laser dynamics under external optical injection. We demonstrate that optical injection can improve the properties of mode-locked lasers in terms of the time-bandwidth product, noise and pulse stability. Also this work provides the estimate of locking range for a passively ML semiconductor laser subjected …

Quantum-Dot Mode-Locked Lasers With Optical Injection, Tatiana Habruseva

Theses

In this thesis novel stabilised ultra-fast pulse sources for a range of practical applications have been developed.

Semiconductor mode-locked lasers have much promise as sources of short, low- jitter, high repetition rate pulses. Development of stabilised semiconductor sources is in a great demand for applications, such as optical telecommunications, frequency metrology, optical sampling and clock recovery. Arbitrary waveform generation, wavelength-division and orthogonal-frequency-division multiplexing techniques need wide stable frequency combs with low phase noise. A low level of pulse-to-pulse timing fluctuations is essential for clock recovery, optical sampling and optical time- division multiplexing. Therefore, this work dealing with the development of …