NUI Maynooth Eprint Archive
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Design and Analysis of Quasioptical Components for use in Terahertz Optics and Future CMB Missions
No full textThe main topic of this thesis concerns itself with the development and analysis
of optical components used in CMB (Cosmic Microwave Background) missions
in the terahertz frequency spectrum. In particular, the optical performance of
PRISTINE, a mission proposal for the ESA fast (F) mission call and a PLA
(Polylatic Acid) GRIN (Gradient Index) lens was analysed using GBM (Gaussian
Beam Mode) theory and PO (Physical Optics). This thesis also includes the work
the author did as part of an international team of 16 students to design a candidate
ESA mission. The final chapter, therefore, concerns itself with “Geophysics from
Space using Micro-or Nano-Satellite Constellations” and is separate from the rest
of the thesis.
Detailed analysis of PRISTINE was carried out in GRASP 10.5 a commercial
package which uses PTD (Physical Theory of Diffraction ) and PO to measure
the EM (Electromagnetic ) radiation generated from reflector antennas. The EM
fields predicted from GRASP were compared with GBMA (Gaussian Beam Mode
Analysis). The beam quality of PRISTINE was tested using its Gaussicity and
ellipticity (this was the chosen method used to compare the simulated data with
the theoretically predicted data). Each surface of PRISITNE’s twelve mirror pFTS
(polarising Fourier Transform Spectrometer) was designed using code written by
the author to optimise the focusing and collimation of each elliptical surface from
criteria outlined in Chapter 3.
Chapter 4 deals with the design, manufacturing and analysis of a 3-D printed PLA
GRIN lens designed to focus W-band radiation (75-110 GHz) 250 mm from the
lens. For this, a commercial package known as CST microwave was used to analyse
the refracted radiation. The simulated radiation was also compared with GBM
analysis and the experimental lab data performed in Maynooth University’s VNA
(Vector Network Analyser) laboratory. Along with this, some material analysis
was performed at 100 GHz in the laboratory to determine the permittivity of the
PLA. The final section of this thesis moves away from quasi-optical analysis and
instead concerns itself with Geophysics. MAGMA-C is a proposed eight satellite
constellation in a Low Earth Orbit (LEO) to measure the Earth’s magnetic field to
study the induced magnetic field in the mantle. The primary goal of the MAGMA�C mission is to map Earth’s mantle conductivity derived from its induced magnetic
field. The secondary goal of this mission is to use this conductivity profile to better
estimate the water content of the mantle
Where we were then: An illuminative evaluation of teacher knowledge, beliefs and practices in relation to Level 2 Learning Programmes and inclusion in a mainstream post primary school.
No full textThis article reports the findings of the first phase of a case study exploring the impact of collaborative whole-school professional development (CWPD) to enact Level 2 Learning Programmes (L2LP) in a mainstream post-primary school. In Phase 1, a baseline in relation to the school’s existing engagement with and knowledge, practice, and beliefs around L2LP and inclusion, was established in order to ascertain the staff CWPD needs and inform the subsequent design, implementation, and evaluation of the whole-school professional development in phase two which are reported elsewhere (Flood, 2019). Though the research explored the voices of students, parents, teachers, and special needs assistants (SNA), this article will focus on teachers’ perspectives and practices. Sixteen teachers, including the principal and the special educational needs coordinator (SENCO), participated in phase one of the research. The findings suggest that despite a stated commitment to inclusion, there were significant gaps in teachers’ knowledge and understanding of policy in relation to L2LP and how to plan for and implement these in their classroom practic
Development of an analytical model for a cyclorotor wave energy device
No full textWe present a new analytical model for a
horizontal axis cyclorotor-based wave energy converter
(WEC). A number of cyclorotor-based WEC concepts and
models, with different numbers of hydrofoils, have previ-
ously been studied. Our model is derived for a horizontal
cyclorotor with 2 hydrofoils. The governing equations are
optimised and converted to the polar coordinate system.
The mechanical model is based on Newton’s second law
for rotation. Rotation is considered in two-dimensional
potential flow, for both monochromatic and panchromatic
waves, including waves generated by the rotating rotor, and
viscous losses. The developed model is very convenient
for modelling, analysis and control design for a cyclorotor
based WEC.
The authors of this work have derived new, exact,
analytic functions for the free surface perturbation and
induced fluid velocity field caused by hydrofoil rotation.
These new formulae significantly decrease the model cal-
culation time, compared to previous models, and increase
the accuracy of the results. We present the results of free
rotation simulations for the rotor in monochromatic and
panchromatic waves obtained with the use of the newly
derived equations
Production of methane and gaseous compounds by surface microbial activity in a small pockmark field, Dunmanus Bay, Ireland
No full textMarine pockmarks are globally widespread seabed depressions, conventionally thought to be formed by the accumulation and expulsion of microbial and thermogenic gas. However, other putative fluids and processes have been implicated in pockmark formation and gas escape to the atmosphere may be underestimated. Given the complex spectrum of aquatic settings, morphologies and sizes, there may also exist a spectrum of physical, chemical and biological processes that form pockmarks. Pockmarks in shallow coastal waters are now understood to be widespread, but the influence of physical dynamics (e.g. tides, storms, etc.), terrestrial processes and anthropogenic activities add considerable spatiotemporal complexity and uncertainty to our understanding of these features. Here, we revisit a field of small (ca. 2 m diameter), shallow
Timing and pace of ice‐sheet withdrawal across the marine–terrestrial transition west of Ireland during the last glaciation
No full textUnderstanding the pace and drivers of marine‐based ice‐sheet retreat relies upon the integration of
numerical ice‐sheet models with observations from contemporary polar ice sheets and well‐constrained palaeo‐
glaciological reconstructions. This paper provides a reconstruction of the retreat of the last British–Irish Ice Sheet (BIIS)
from the Atlantic shelf west of Ireland during and following the Last Glacial Maximum (LGM). It uses marine‐
geophysical data and sediment cores dated by radiocarbon, combined with terrestrial cosmogenic nuclide and optically
stimulated luminescence dating of onshore ice‐marginal landforms, to reconstruct the timing and rate of ice‐sheet
retreat from the continental shelf and across the adjoining coastline of Ireland, thus including the switch from a marine‐
to a terrestrially‐based ice‐sheet margin. Seafloor bathymetric data in the form of moraines and grounding‐zone wedges
on the continental shelf record an extensive ice sheet west of Ireland during the LGM which advanced to the outer shelf.
This interpretation is supported by the presence of dated subglacial tills and overridden glacimarine sediments from
across the Porcupine Bank, a westwards extension of the Irish continental shelf. The ice sheet was grounded on the
outer shelf at ~26.8 ka cal BP with initial retreat underway by 25.9 ka cal BP. Retreat was not a continuous process but
was punctuated by marginal oscillations until ~24.3 ka cal BP. The ice sheet thereafter retreated to the mid‐shelf where it
formed a large grounding‐zone complex at ~23.7 ka cal BP. This retreat occurred in a glacimarine environment. The
Aran Islands on the inner continental shelf were ice‐free by ~19.5 ka BP and the ice sheet had become largely
terrestrially based by 17.3 ka BP. This suggests that the Aran Islands acted to stabilize and slow overall ice‐sheet retreat
once the BIIS margin had reached the inner shelf. Our results constrain the timing of initial retreat of the BIIS from
the outer shelf west of Ireland to the period of minimum global eustatic sea level. Initial retreat was driven, at least in
part, by glacio‐isostatically induced, high relative sea level. Net rates of ice‐sheet retreat across the shelf were slow
(62–19 m a−1
) and reduced (8 m a−1
) as the ice sheet vacated the inner shelf and moved onshore. A picture therefore
emerges of an extensive BIIS on the Atlantic shelf west of Ireland, in which early, oscillatory retreat was followed by
slow episodic retreat which decelerated further as the ice margin became terrestrially based. More broadly, this
demonstrates the importance of localized controls, in particular bed topography, on modulating the retreat of marine‐
based sectors of ice sheets
Family Talk versus usual services in improving child and family psychosocial functioning in families with parental mental illness (PRIMERA—Promoting Research and Innovation in Mental health services for families and children): study protocol for a randomised controlled trial
No full textBackground: Parental mental illness is common and can lead to dependent children incurring a high risk of
developing mental disorders, physical illness, and impaired educational and occupational outcomes. Family Talk is
one of the better known interventions designed to prevent the intergenerational transmission of mental illness.
However, its evidence base is small, with few robust independent randomised controlled trials, and no associated
process or cost evaluations. The PRIMERA (Promoting Research and Innovation in Mental hEalth seRvices for
fAmilies and children) research programme involves a mixed method evaluation of Family Talk which is being
delivered in mental health settings in Ireland to improve child and family psychosocial functioning in families with
parental mental illness
“L’enfer, c’est les autres”: Proximity as an Ethical Problem during COVID-19
No full textDuring the COVID-19 emergency, people around the world are debating concepts like physical distancing, lockdown, and sheltering in place. The ethical significance of proximity—that is, closeness or farness as ethical qualities of relations (Strathern 2020)—is thus being newly troubled across a range of habits, practices, and personal relationships. Through five case studies from Australia, Ireland, New Zealand, South Africa, and the United States, contributors to this Colloquy shed light on what the hype of the pandemic often conceals: the forms of ethical reflection, reasoning, and conduct fashioned during the pandemic
The End of Intimacy
No full textThough comparisons between HIV and SARS-CoV-2 are of limited use, many people experience the epidemics simultaneously. For those of us living with HIV, every comment on COVID-19 becomes a fretful allegory of HIV, and the ethical lessons that COVID-19 teaches will inevitably be brought to bear on how we understand the meaning of the HIV epidemic, especially as it pertains to sexuality. This essay describes some of the ways gay men in Dublin, Ireland, reasoned about the ethics of sex during lockdown
Risk of Tradition: With de Certeau toward a Postmodern Catholic Theory
No full textTRADITION IS NOT USUALLY ASSOCIATED with risk. However,
as one gets into the business of defining what tradition is, theologically speaking, complex tensions come to light. Take the following statement by Yves Congar: “Tradition, then, comprises two equally vital aspects: one of development and one of conservation.”1 Post-Newman, it is uncontroversial to assume that tradition possesses an element of development. But how much development? What kind of development? What kind of conservation? How
are development and conservation related? The risk inherent in the interplay of development and conservation is not only that there could be “too much” of one or the other; it is also that their relationship may be misconstrued altogether
The Role of EU State Aid Law as a “Risk Management Tool” in the COVID-19 Crisis
No full textThis article discusses the role of European Union (EU) State aid law in the COVID-19 crisis. It contends that different Treaty derogations have played unique roles in addressing the core determinants of the economic risk linked to the pandemic (ie the “exposure” to lockdown measures and the “vulnerability” of certain sectors to them), and in increasing the resilience of national economies. Moreover, this article examines the extent to which EU State aid law has been used to manage and mitigate health risks, by allowing Member States to enhance the preparedness and capacity of their healthcare sector (broadly conceived) to respond to the pandemic. On the whole, this article maintains that State aid control has been used by the European Commission as an important “risk management tool”, and it highlights the role of the Commission as the crisis management authority