964 resultados para Nd^3


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Stair na Gaeilge i gCo. Thiobraid rann i rith na trimhse 1700-1901 at romhadh sa trchtas seo. Tar is a clra agus a comhthacs a shuomh i gCaibidil a hAon, dantar scrobhaithe an cheantair a ireamh, fara trchtaireacht orthu, i gCaibidil a D. I gCaibidl a Tr agus a Ceathair, fachtar ar thionchar na hEaglais Caitlic agus Eaglais na hireann (i measc eaglais Protastnacha eile) ar an dteangain. I gCaibidil a Cig, faightear splachadh ar ghnithe agsla de shaocht an chontae, ag tabhairt largais ar thirg na scrobhaithe, ar leabhair a clbhualadh sa rigin, agus ar fhil mra na hite, leithid Liam Daill U Ifearnin, ag sonr limistir faoi leith, an t-oirdheisceart, mar shampla. Lirtear ifeacht na gcumann Gaelach agus na ndograiseoir iomadla a bhain leo. bhar suime, leis, feidhm na Gaeilge sna cirteanna dl. Tugtar faisnis i gCaibidil a S ar fhianaise cuairteoir ar an Ghaeilge mar urlabhra i dTiobraid rann. Is anseo chomh maith a deintear anails ar Dhaonirimh na mblianta 1861-1901, le mrchuid adhmaid baint as ceann 1901 go hirithe. Breactar as ainmneacha sagart agus minteoir le Gaeilge, agus trchtar ar aicm suntasacha eile, na piln agus na saighdiir a raibh an teanga sin ina mbal acu. Tugtar le chile d rir na snithn difrila eolais ar an diche ar bhealach nr tharla cheana don gcontae casta fairsing seo le haghaidh na trimhse at idir lmha ag an saothar.

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Electron microscopy (EM) has advanced in an exponential way since the first transmission electron microscope (TEM) was built in the 1930s. The urge to see things is an essential part of human nature (talk of seeing is believing) and apart from scanning tunnel microscopes which give information about the surface, EM is the only imaging technology capable of really visualising atomic structures in depth down to single atoms. With the development of nanotechnology the demand to image and analyse small things has become even greater and electron microscopes have found their way from highly delicate and sophisticated research grade instruments to key-turn and even bench-top instruments for everyday use in every materials research lab on the planet. The semiconductor industry is as dependent on the use of EM as life sciences and pharmaceutical industry. With this generalisation of use for imaging, the need to deploy advanced uses of EM has become more and more apparent. The combination of several coinciding beams (electron, ion and even light) to create DualBeam or TripleBeam instruments for instance enhances the usefulness from pure imaging to manipulating on the nanoscale. And when it comes to the analytic power of EM with the many ways the highly energetic electrons and ions interact with the matter in the specimen there is a plethora of niches which evolved during the last two decades, specialising in every kind of analysis that can be thought of and combined with EM. In the course of this study the emphasis was placed on the application of these advanced analytical EM techniques in the context of multiscale and multimodal microscopy multiscale meaning across length scales from micrometres or larger to nanometres, multimodal meaning numerous techniques applied to the same sample volume in a correlative manner. In order to demonstrate the breadth and potential of the multiscale and multimodal concept an integration of it was attempted in two areas: I) Biocompatible materials using polycrystalline stainless steel and II) Semiconductors using thin multiferroic films. I) The motivation to use stainless steel (316L medical grade) comes from the potential modulation of endothelial cell growth which can have a big impact on the improvement of cardio-vascular stents which are mainly made of 316L through nano-texturing of the stent surface by focused ion beam (FIB) lithography. Patterning with FIB has never been reported before in connection with stents and cell growth and in order to gain a better understanding of the beam-substrate interaction during patterning a correlative microscopy approach was used to illuminate the patterning process from many possible angles. Electron backscattering diffraction (EBSD) was used to analyse the crystallographic structure, FIB was used for the patterning and simultaneously visualising the crystal structure as part of the monitoring process, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to analyse the topography and the final step being 3D visualisation through serial FIB/SEM sectioning. II) The motivation for the use of thin multiferroic films stems from the ever-growing demand for increased data storage at lesser and lesser energy consumption. The Aurivillius phase material used in this study has a high potential in this area. Yet it is necessary to show clearly that the film is really multiferroic and no second phase inclusions are present even at very low concentrations ~0.1vol% could already be problematic. Thus, in this study a technique was developed to analyse ultra-low density inclusions in thin multiferroic films down to concentrations of 0.01%. The goal achieved was a complete structural and compositional analysis of the films which required identification of second phase inclusions (through elemental analysis EDX(Energy Dispersive X-ray)), localise them (employing 72 hour EDX mapping in the SEM), isolate them for the TEM (using FIB) and give an upper confidence limit of 99.5% to the influence of the inclusions on the magnetic behaviour of the main phase (statistical analysis).

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In moments of rapid social changes, as has been witnessed in Ireland in the last decade, the conditions through which people engage with their localities though memory, individually and collectively, remains an important cultural issue with key implications for questions of heritage, preservation and civic identity. In recent decades, cultural geographers have argued that landscape is more than just a view or a static text of something symbolic. The emphasis seems to be on landscape as a dynamic cultural process an ever-evolving process being constructed and re-constructed. Hence, landscape seems to be a highly complex term that carries many different meanings. Material, form, relationships or actions have different meanings in different settings. Drawing upon recent and continuing scholarly debates in cultural landscapes and collective memory, this thesis sets out to examine the generation of collective memory and how it is employed as a cultural tool in the production of memory in the landscape. More specifically, the research considers the relationships between landscape and memory, investigating the ways in which places are produced, appropriated, experienced, sensed, acknowledged, imagined, yearned for, appropriated, re-appropriated, contested and identified with. A polyvocal-bricoleur approach aims to get below the surface of a cultural landscape, inject historical research and temporal depth into cultural landscape studies and instil a genuine sense of inclusivity of a wide variety of voices (role of monuments and rituals and voices of people) from the past and present. The polyvocal-bricoleur approach inspires a mixed method methodology approach to fieldsites through archival research, fieldwork and filmed interviews. Using a mixture of mini-vignettes of place narratives in the River Lee valley in the south of Ireland, the thesis explores a number of questions on the fluid nature of narrative in representing the story and role of the landscape in memory-making. The case studies in the Lee Valley are harnessed to investigate the role of the above questions/ themes/ debates in the act of memory making at sites ranging from an Irish War of Independence memorial to the River Lees hydroelectric scheme to the valleys key religious pilgrimage site. The thesis investigates the idea that that the process of landscape extends not only across space but also across time that the concept of historical continuity and the individual and collective human engagement and experience of this continuity are central to the processes of remembering on the landscape. In addition the thesis debates the idea that the production of landscape is conditioned by several social frames of memory that individuals remember according to several social frames that give emphasis to different aspects of the reality of human experience. The thesis also reflects on how the process of landscape is represented by those who re-produce its narratives in various media.

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Real time monitoring of oxygenation and respiration is on the cutting edge of bioanalysis, including studies of cell metabolism, bioenergetics, mitochondrial function and drug toxicity. This thesis presents the development and evaluation of new luminescent probes and techniques for intracellular O2 sensing and imaging. A new oxygen consumption rate (OCR) platform based on the commercial microfluidic perfusion channel -slides compatible with extra- and intracellular O2 sensitive probes, different cell lines and measurement conditions was developed. The design of semi-closed channels allowed cell treatments, multiplexing with other assays and two-fold higher sensitivity to compare with microtiter plate. We compared three common OCR platforms: hermetically sealed quartz cuvettes for absolute OCRs, partially sealed with mineral oil 96-WPs for relative OCRs, and open 96-WPs for local cell oxygenation. Both 96-WP platforms were calibrated against absolute OCR platform with MEF cell line, phosphorescent O2 probe MitoXpress-Intra and time-resolved fluorescence reader. Found correlations allow tracing of cell respiration over time in a high throughput format with the possibility of cell stimulation and of changing measurement conditions. A new multimodal intracellular O2 probe, based on the phosphorescent reporter dye PtTFPP, fluorescent FRET donor and two-photon antennae PFO and cationic nanoparticles RL-100 was described. This probe, called MM2, possesses high brightness, photo- and chemical stability, low toxicity, efficient cell staining and high-resolution intracellular O2 imaging with 2D and 3D cell cultures in intensity, ratiometric and lifetime-based modalities with luminescence readers and FLIM microscopes. Extended range of O2 sensitive probes was designed and studied in order to optimize their spectral characteristics and intracellular targeting, using different NPs materials, delivery vectors, ratiometric pairs and IR dyes. The presented improvements provide useful tool for high sensitive monitoring and imaging of intracellular O2 in different measurement formats with wide range of physiological applications.

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Alternative food initiatives (AFIs) have been described as an attempt to change and improve aspects of how the food system operates. They are focused around more traditional, local and sustainable food production and circulation. AFIs such as farmers markets, allotments and community gardens, share a desire to reduce the number of steps food goes through from production to plate. The role of these initiatives in the food system, and their potential to impact real change, has however been questioned. Working to better understand this issue is a central concern of this research. To do this a two tier analysis has been deployed. The first tier involves identifying the characteristics and general dynamics of AFIs. Bourdieus theory of practice, and the theories of field and capital, are the concepts applied. The research then uses these findings in the second tier of analysis concerned with relating AFI characteristics and dynamics back to their key traits, positive and negative, as well as arguments made about AFIs role identified from previous research. Another part of this second tier of analysis is exploring if AFIs, the producers, consumers, organisations and groups that make up this phenomenon, can be considered a social movement. AFIs can be referred to collectively as a social movement, but are not often explored theoretically from this perspective. AFIs in Ireland provide the empirical context for this research. A series of qualitative interviews in four areas of Ireland, as well as evidence from primary and secondary sources are analysed. The research finds that AFIs can be understood as the potential beginnings of a lifestyle social movement. Leaders are of central importance to its development. It is also found that an important role of AFIs is revitalising, supporting and contributing to food culture.

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Using the lenses of contemporary cultural geography, this research develops an understanding of pilgrimage as a relational and reciprocal process that co-produces self and world. Drawing on the phenomenology of Merleau-Ponty, I argue that through the performances and experiences of contemporary pilgrimage in Ireland, participants and locations emerge as pilgrims and pilgrimage places. This approach unites different strands of cultural geography, including the mobilities field, more-than representational concerns, discussions of embodiment and practice, emotional and affective geographies, and religious and spiritual geographies. I explore how pilgrimage is an active process in which self and world, belief and practice, and the numinous and material entwine and merge. An autoethnographic methodology is enacted as an embodied, intersubjective, and reflexive research approach that incorporates the motivations, experiences, and beliefs of research participants, alongside my own descriptions and reflections. The methodology is focused on encountering and documenting pilgrimage practices as they occur in place and relating these embodied spatial practices to the accounts of pilgrims. The insights generated by engagements with research participants and through my own pilgrimages, offer new appreciations of the enduring appeal of pilgrimage in Ireland as a religious-spiritual and cultural activity that allows people to express personal intentions, to develop their faith, and to seek numinous encounters. Through the pilgrimages at Lough Derg, Croagh Patrick, and three holy wells, I produce a layered account of the empirical circumstances of the practices. The presentation of these places and events is enhanced by the use of evocative images and audiovisual recordings. By centring my study on the practices and experiences of different pilgrimages in present-day Ireland, and critically deploying strands of cultural geography and pilgrimage studies, this research produces new qualitative understandings of pilgrimage and contributes to discussions concerned with the relationships between self and world.

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Background: The Human Papillomavirus (HPV) is one of the worlds most common sexually transmitted infections, and a causative factor of oropharyngeal, anal and penile cancers in males. Worldwide, an estimated 39,000 HPV-associated cancers occur each year in men. The highest rates of HPV infection are found in adults aged 18 to 28 years. Clinical evidence indicates that use of a condom in addition to obtaining the HPV vaccine provides the greatest protection from HPV infections. Aim: To explore young mens attitudes, beliefs, and behavioural intention in relation to receiving the HPV vaccine and using a condom correctly and consistently. Collectively, both behaviours are linked to the prevention of HPV transmission and associated infections with HPV. Method: A multi- phase study, underpinned by the Theory of Planned Behaviour, involving a qualitative belief elicitation, pilot, and quantitative cross-sectional study was conducted. A belief elicitation (n=12) phase was used to generate items to include in a newly developed research instrument. Post pilot the research instrument was utilised in a cross sectional online survey to explore the attitudes, beliefs, and behavioural intention of young men (n= 359) with regard to receiving the HPV vaccine, and using a condom correctly and consistently. Data Collection: Data collection took place over a three month time frame. Male participants were recruited from a university in Southern Ireland via a student email system, as well as posting advertisements on numerous health, social and sports websites. Sample: Three hundred and fifty nine male participants aged 18- 28 years completed the online questionnaire. Data Analysis: Data were analysed using SPSS. Descriptive, correlational, multiple and hierarchical regression analysis were performed on the indirect and direct variables of the Theory of Planned Behaviour i.e. attitude, subjective norm, perceived behavioural control, and intention. Status variables were also included in descriptive analysis and hierarchical regressions. Findings are presented through text and graphical representation. Results: Alarming sexual health statistics identified that only 44.3% of participants always used a condom, and 78.6% never used a condom for oral sex. Furthermore, findings reveal that the constructs of the Theory of Planned Behaviour adequately measure males attitudes, beliefs and behavioural intention with regard to both behaviours. The Theory of Planned Behaviour has assisted in identifying how social pressures play an influential role in relation to males receiving the HPV vaccine. Attitudes presented as the most significant predictor of males intentions to use a condom correctly and consistently. Intention to perform both behaviours was identified as moderate to high. Conclusion: This study has contributed to the field of HPV research, as it is the first piece of research to explore preventative HPV behaviours i.e. receiving the HPV vaccine, and condom use, amongst young males, utilising the Theory of Planned Behaviour. A deeper understanding of young males attitudes, beliefs, and behavioural intention on this topic has been achieved. Additionally, a new robust research instrument has been constructed. Findings from this study will undoubtedly help in the implementation of the HPV vaccine in Ireland, as well as influence health promotion campaigns aimed at young males, addressing the topic of condom use.

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Internal tandem duplication of FMS-like receptor tyrosine kinase (FLT3-ITD) has been associated with an aggressive AML phenotype. FLT3-ITD expressing cell lines have been shown to generate increased levels of reactive oxygen species (ROS) and DNA double strand breaks (dsbs). However, the molecular basis of how FLT3-ITD-driven ROS leads to the aggressive form of AML is not clearly understood. Herein, we observe that the majority of H2O2 in FLT3-ITD-expressing MV4-11 cells colocalises to the endoplasmic reticulum (ER). Furthermore, ER localisation of ROS in MV4-11 cells corresponds to the localisation of p22phox, a small membrane-bound subunit of NOX complex. Furthermore, we show that 32D cells, a myeloblast-like cell line transfected with FLT3-ITD, possess higher steady protein levels of p22phox than their wild type FLT3 (FLT3-WT)-expressing counterparts. Moreover, the inhibition of FLT3-ITD, using various FLT3 tyrosine kinase inhibitors, uniformly results in a posttranslational downregulation of p22phox. We also show that depletion of NOX2 and NOX4 and p22phox, but not NOX1 proteins causes a reduction in endogenous H2O2 levels. We show that genomic instability induced by FLT3-ITD leads to an increase in nuclear levels of H2O2. The presence of H2O2 in the nucleus is largely reduced by inhibition of FLT3-ITD or NOX. Furthermore, similar results are also observed following siRNA knockdowns of p22phox or NOX4. We demonstrate that 32D cells transfected with FLT3-ITD have a higher level of DNA damage than 32D cells transfected with FLT3-WT. Additionally, inhibition of FLT3-ITD, p22phox and NOX knockdowns decrease the number of DNA dsbs. In summary, this study presents a novel mechanism of genomic instability generation in FLT3-ITD-expressing AML cells, whereby FLT3-ITD activates NOX complexes by stabilising p22phox. This in turn leads to elevated generation of ROS and DNA damage in these cells.

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This thesis focuses on the complex relationship between representations of the human body and the formal processes of mise-en-scne in three consecutive films by the writer-director Paul Schrader: American Gigolo (1980), Cat People (1982) and Mishima: A Life in Four Chapters (1985). While Schraders work has typically been critiqued under the broad category of masculinity in crisis (and often as a subset of the films of his more famous long-time collaborator, Martin Scorsese), I focus on a fiveyear early period of his filmography when he sought to explore his key themes of bodily crisis, fragmentation and alienation through an unusually intense focus upon the expressive potential of film form, specifically via the combined elements of colour, lighting, camerawork and production design. By approaching these three films as corporeal character studies of troubled figures whose emotional and psychosexual neurosis is experienced in and through the body, I will locate Schraders filmmaking process and style within the thematic and aesthetic contexts of both his own early film criticism and the European and Japanese art cinemas that he claims as his primary influence. In doing so, I will establish Schraders position as a director whose literary and theological background differentiated him from his peers of the postclassical Hollywood generation, and who thus continually sought to develop his own visual literacy through his relationship with the camera and his collaborations with more overtly style-oriented film artists. But instead of merely focusing on mise-en-scne to gain a formalist appreciation of these films, I mobilise stylistic analysis as a new critical approach towards the problematic discourses of identity and embodiment that have haunted Schraders career from the beginning. In particular, I argue that paying closer attention to Schraders formal choices sheds new light on how these films which he approached as exercises in style repeatedly deal with the volatile and unavoidably body-oriented categories of race, gender and sexuality. In the process, I argue that a formalist attentiveness to mise-en-scne can also provide valuable cultural insights into Schraders oeuvre.

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This study investigates how the experiences of Junior Infants are shaped in multigrade classes. Multigrade classes are composed of two or more grades within the same classroom with one teacher having responsibility for the instruction of all grades in this classroom within a time-tabled period (Little, 2001, Mason and Doepner, 1998). The overall aim of the research is to problematize the issues of early childhood pedagogy in multigrade classes in the context of children negotiating identities, positioning and power relations. A Case Study approach was employed to explore the perspectives of the teachers, children and their parents in eight multigrade schools. Concurrent with this, a nation-wide Questionnaire Survey was also conducted which gave a broader context to the case study findings. Findings from the research study suggest that institutional context is vitally important and finding the space to implement pedagogic practices is a highly complex matter for teachers. While a majority of teachers reported the benefits for younger children being in mixed-age settings alongside older children, only a minority of case study school teachers demonstrated how it is possible to promote classroom climates which were provided multiple opportunities for younger children to engage fully in classrooms. The findings reveal constraints on pedagogical practice which included: time pressures within the job, an increase in diversity in pupil population, meeting special needs, large class sizes, high pupil/teacher ratios, and planning/organisation of tasks which intensified the complexities of addressing the needs of children who differ significantly in age, cognitive, social and emotional levels. An emergent and recurrent theme of this study is the representation of Junior Infants as apprentices in their communities of practice who contributed in peripheral ways to the practices of their groups (Lave and Wenger, 1991, Wenger, 1998). Through a continuous process of negotiation of meaning, these pupils learned the knowledge and skills within their communities of practice that empowered some to participate more fully than others. The children in their figured worlds (Holland, Lachiotte, Skinner and Caine 1998) occupy identities which are influenced by established arrangements of resources and practices within that community as well as by their own agentive actions. Finally, the findings of the study also demonstrate how the dimension of power is central to the exercise of social relations and pedagogical practices in multigrade classes.

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Background/Aim: It has been demonstrated that a number of pathologies occur as a result of dysregulation of the immune system. Whilst classically associated with apoptosis, the Fas (CD95) signalling pathway plays a role in inflammation. Studies have demonstrated that Fas activation augments TLR4-mediated MyD88-dependent cytokine production. Studies have also shown that the Fas adapter protein FADD is required for RIG-I-induced IFN production. As a similar signalling pathway exists between RIG-I, TLR3 and the MyD88- independent of TLR4, we hypothesised that Fas activation may modulate both TLR3- and TLR4-induced cytokine production. Results: Fas activation reduced poly I:C-induced IFN, IL-8, IL-10 and TNF production whilst augmenting poly I:C-, poly A:U- and Sendai virus-induced IP-10 production. TLR3-, RIG-I- and MDA5-induced IP-10 luciferase activation were inhibited by the Fas adapter protein FADD using overexpression studies. Poly I:C-induced phosphorylation of p-38 and JNK MAPK were reduced by Fas activation. Overexpression of FADD induced AP-1 luciferase activation. Point mutations in the AP-1 binding site enhanced poly I:C-induced IP- 10 production. LPS-induced IL-10, IL-12, IL-8 and TNF production were enhanced by Fas activation, whilst reducing LPS-induced IFN production. Absence of FADD using FADD-/- MEFs resulted in impaired IFN production. Overexpression studies using FADD augmented TLR4-, MyD88- and TRIF-induced IFN luciferase activation. Overexpression studies also suggested that enhanced TLR4-induced IFN production was independent of NFB activation. Conclusion: Viral-induced IP-10 production is augmented by Fas activation by reducing the phosphorylation of p-38 and JNK MAPKs, modulating AP-1 activation. The Fas adapterprotein FADD is required for TLR4-induced IFN production. Studies presented here demonstrate that the Fas signalling pathway can therefore modulate the immune response. Our data demonstrates that this modulatory effect is mediated by its adapter protein FADD, tailoring the immune response by acting as a molecular switch. This ensures the appropriate immune response is mounted, thus preventing an exacerbated immune response.

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This thesis conducts a formal study of the poetry of Gloria Anzalda and Lorna Dee Cervantes, placing their work in dialogue with genre and style. These two Chicana poets are exemplary of politicised experimentation with poetics, underpinned by a keen awareness of the rich history of form, genre and style. In the work of each poet, two poetic modes are examined: one traditional, and one experimental. Anzaldas uses of the dramatic monologue as a border genre, and her construction of [auto]poetics, stemming from her multi-genre, autobiographical approach to writing, are considered. Cervantess complex approach to the construction of docupoetics that achieves a depth of field in terms of merging a multidimensional approach to aesthetics with highly politicised transnational content, as well as her engagement with the longstanding poetic of elegy via various formal points of entry, is investigated. These poetic modes are primarily explored via close readings, supported by a multidisciplinary framework that includes Anzaldas feminist theories of identity and writing, abjection theory, postcolonialism, and transnationalism. Overall, these four key areas demonstrate the ways in which aesthetics is a crucial consideration in the exploration of the broader issues of content and context in Chicana poetry.

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The student bullying of teachers (SBT) is a distinct and complex form of bullying with a multiplicity of diverse, changeable and intersecting causes which is experienced by and affects teachers in a variety of ways. SBT is both a national and an international phenomenon which is under-recognised in academic, societal and political spheres, resulting in limited conceptual understanding and awareness of the issue. This study explores teachers experiences of SBT behaviours in Irish second level schools as well as teachers perceptions regarding training, policies and supports in Ireland to address the issue. Specifically, the study seeks to explore the influence of historical low State intervention in education on contemporary policies and supports to deal with SBT in Ireland. A mixed methods approach involving a survey of 531 second level school teachers and 17 semi-structured interviews with teachers, Year Heads and representatives from teacher trade unions and school management bodies was employed to collect and analyse data. Findings indicate that SBT behaviours are prevalent in many forms in Irish second level schools. The hidden nature of the phenomenon has simultaneously contributed to and is reinforced by limited understanding of the issue as well as teachers reluctance to disclose their experiences. Findings reveal that teachers perceive the contemporary policies, training and support structures in Ireland to be inadequate in equipping them to effectively deal with SBT. State intervention in addressing SBT behaviours to date, has been limited, therefore many teachers are forced to respond to the issue based on their own initiatives and assumptions rather than from an informed critically reflective approach, supported by national guidelines and sufficient State investment. This has resulted in a piecemeal, un-coordinated and ad-hoc approach to SBT in Irish schools both in terms of teachers management of SBT behaviours and with respect to the supports extended to staff. The potential negative consequences of SBT behaviours on teachers wellbeing and professional performance and thus, on the education system itself, underlines the need for a strategic, evidence-based, resourced and integrated approach which includes, as a pivotal component, consultation with teachers, whose contribution to the process is crucial.

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Dilute bismide alloys, containing small fractions of bismuth (Bi), have recently attracted interest due to their potential for applications in a range of semiconductor devices. Experiments have revealed that dilute bismide alloys such as GaBixAs1x, in which a small fraction x of the atoms in the III-V semiconductor GaAs are replaced by Bi, exhibit a number of unusual and unique properties. For example, the band gap energy (E g) decreases rapidly with increasing Bi composition x, by up to 90 meV per % Bi replacing As in the alloy. This band gap reduction is accompanied by a strong increase in the spin-orbit-splitting energy (SO) with increasing x, and both E g and SO are characterised by strong, composition-dependent bowing. The existence of a SO > E g regime in the GaBixAs1x alloy has been demonstrated for x 10%, a band structure condition which is promising for the development of highly efficient, temperature stable semiconductor lasers that could lead to large energy savings in future optical communication networks. In addition to their potential for specific applications, dilute bismide alloys have also attracted interest from a fundamental perspective due to their unique properties. In this thesis we develop the theory of the electronic and optical properties of dilute bismide alloys. By adopting a multi-scale approach encompassing atomistic calculations of the electronic structure using the semi-empirical tight-binding method, as well as continuum calculations based on the kp method, we develop a fundamental understanding of this unusual class of semiconductor alloys and identify general material properties which are promising for applications in semiconductor optoelectronic and photovoltaic devices. By performing detailed supercell calculations on both ordered and disordered alloys we explicitly demonstrate that Bi atoms act as isovalent impurities when incorporated in dilute quantities in III-V (In)GaAs(P) materials, strongly perturbing the electronic structure of the valence band. We identify and quantify the causes and consequences of the unusual electronic properties of GaBixAs1x and related alloys, and our analysis is reinforced throughout by a series of detailed comparisons to the results of experimental measurements. Our kp models of the band structure of GaBixAs1x and related alloys, which we derive directly from detailed atomistic calculations, are ideally suited to the study of dilute bismide-based devices. We focus in the latter part of the thesis on calculations of the electronic and optical properties of dilute bismide quantum well lasers. In addition to developing an understanding of the effects of Bi incorporation on the operational characteristics of semiconductor lasers, we also present calculations which have been used explicitly in designing and optimising the first generation of GaBixAs1x-based devices.

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Go promha, is trchtas seo a dhanann staidar ar ghn de litrocht iar-chlasaiceach na Gaeilge. Baineann s go hirithe leis an sraith chaointe n marbhna i bhfoirm varsaochta a cumadh do Shamas g Mac Coitir (1689-1720), duine uasal Caitliceach Charraig Tuathail, Co. Chorca, nuair a ciontaodh in igni Elizabeth Squibb, bean de Chumann na gCarad; nuair a cuireadh pions an bhis air; agus nuair a crochadh i gCathair Chorca an 7 Bealtaine, 1720. thaobh na staire de, scrdatear Clann Choitir mar shampla de theaghlach nr cheil a ndlseacht do chis pholaitiil na Stobhartach agus a sheas an fd go crga faoi mar a bh a ngreim polaitiil dhaingni ag an gCinsealacht Phrotastnach dheireadh an 17 haois amach. Tagratear do sheicteachas na socha comhaimseartha agus don teannas idir an pobal Caitliceach agus an pobal Protastnach ag an am. Dantar scagadh ar an varsaocht mar fhoinse luachmhar do dhearcadh mshsta an mhraimh Chaitlicigh ar struchtr polaitiil chontae Chorca (agus na hireann) i dtosach an 18 haois. Is feiniman liteartha an dls varsaochta seo a bhaineann go hirithe le traidisin liteartha Chorca. T na dnta curtha in eagar agus aistrichn go Barla curtha ar fil: is seo cro an trchtais. T an t-eagrn bunaithe ar scrd cuimsitheach ar thraidisin na ls; plitear modheolaocht na heagarthireachta. Dantar iarracht ar na dnta a shuomh sa traidisin casta liteartha sa trchtaireacht tosaigh; sa chuid eile den bhfearas scoliriil, scrdatear ceisteanna a bhaineann le crsa teanga, foclra, meadarachta agus stle. T innacsanna agus liosta foins le fil i ndeireadh an trchtais.