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Abstract Tunable-focal length LC lens with hole-patterned electrode have been fabricated in this study. Liquid crystals (LCs) are excellent electro-optic materials with electrical and optical anisotropies. Their optical properties can easily be varied by external electric field. Hence according the electro-optic properties, we made the tunable LC lens. In this study a novel conoscopy method has been applied to analyze the LC lens. First, we study the causes of the focusing and the optical properties of LC lens, and measure the focal length with varying voltage. Second, by analyzing the figure patterns formed with conoscopy method. We study the LC molecules reorientation caused by the inhomogeneous electric field distribution. In order to improve the spoiled effect due to the subsidiary domain in the LC lens, three different structures of LC lens have been fabricated and the focusing effect has been discussed.

El objetivo fundamental de la presente Tesis Doctoral ha sido comparar dos técnicas cromatográficas acopladas utilizadas en Cromatografía Líquida (acoplamiento LC-LC y acoplamiento SPE-LC), mediante su aplicación al análisis de residuos de diferentes familias de herbicidas en muestras de agua. El acoplamiento LC-LC con detección UV se ha utilizado para la determinación de residuos de bromacilo y diuron, de cuatro herbicidas triazínicos, y de atrazina junto a sus principales productos de transformación. Para ello, se han desarrollado tres procedimientos analíticos rápidos y selectivos basados en la inyección directa de 2 ml de muestra acuosa en el sistema LC-LC, con límites de detección entre 0.1 y 0.5 µg·l-1. La incorporación de una sencilla etapa previa de SPE "off-line" (en la determinación de triazinas y productos de transformación) permite disminuir los límites de detección hasta niveles inferiores a 0.1 µg·l-1, pudiendo aplicarse los métodos desarrollados a muestras de aguas potables. El acoplamiento "on-line" SPE-LC-DAD se ha llevado a cabo mediante modificación de un equipo instrumental originalmente diseñado para llevar a cabo SPE "off-line" (el ASPEC XL), habiéndose desarrollado procedimientos para la determinación de carbaril y su principal producto de transformación (1-naftol), bromacilo con cinco herbicidas ureicos, triazinas y TP´s, y finalmente, seis herbicidas fenilcarbamatos. Cabe destacar la completa automatización de los procedimientos desarrollados así como las altas sensibilidades obtenidas mediante preconcentración de volúmenes de muestra del orden de 50-100 ml. Complementariamente al desarrollo de metodología analítica, se han llevado a cabo estudios de degradación de carbaril a 1-naftol, así como de desmedifam y fenmedifam. En el caso de los fenilcarbamatos se detectaron varios TP´s, quedando pendiente una futura elucidación estructural de los mismos.Los procedimientos desarrollados se han utilizado para realizar control de plaguicidas en aguas superficiales de la Comunidad Valenciana, habiéndose detectado diferentes herbicidas como bromacilo, diuron y algunas triazinas (simazina, terbutilazina, terbutrina y terbumeton). Finalmente, se ha llevado a cabo un estudio comparativo de las dos modalidades de acoplamiento utilizadas en esta Tesis Doctoral, LC-LC y SPE-LC, destacándose las características más relevantes de cada una de ellas (rapidez, sensibilidad, selectividad y mayor o menor carácter multiresidual), mediante el apoyo de los datos experimentales obtenidos a partir de los métodos desarrollados para los distintos herbicidas analizados tanto por LC-LC como por SPE-LC.

Research undertaken within the Sociology of Education frequently highlights concerns about the underachievement of Black students in education and, later, within the labour market. Yet, there are a number of shortcomings associated with research in this area. Firstly, there is a tendency to homogenise the achievement levels of all Black students. Thus observations made about the outcomes of African-Caribbean students are often applied to all other Black groups. When distinctions between African and African Caribbean groups have been made, the achievement levels of students from different African backgrounds are often merged, creating a misleading impression of their different academic outcomes. Secondly, studies seeking to provide explanations for the low attainment levels of Black students are often critical of life within Black families, in particular their assumed use of an „authoritarian‟ parenting style, which is seen as creating psychological problems in children and as hindering their achievement. Effectively, such notions serve to pathologise Black families in Britain. This thesis presents a critique of existing studies concerning Black families in Britain and the academic achievement of Black (African) children, and also seeks to address existing gaps in the knowledge about Black Africans residing in Britain. Life history interviews were conducted with 25 British-Ghanaians who have achieved highly in their academic and professional pursuits. The findings suggest that not all parents adopted an „authoritarian‟ approach when raising their children, and that those who did were influenced by their own socialisation experiences in Ghana. While some respondents experienced some socio-emotional problems resulting from their „authoritarian‟ socialisation, these were generally resolved and did not have a long-term impact on their attainment. The thesis also suggests that the use of discipline, associated with this parenting style, may have had some beneficial effects in relation to respondents‟ academic and professional outcomes.

With the increasing internationalisation of Higher Education, which saw the number of international students double in the first decade of the 21st century according to an OECD report (Rebolledo-Gomez & Ranchin, 2013), universities around the world have been trying to improve the learning experience and enhance student employability in order to maintain an international reputation. Multicultural groupwork, which has the power to "force" students of different cultural backgrounds to work together has been increasingly used in the name of developing students' intercultural skills and prepare them to become "Global Citizens" under this internationalisation of Higher Education agenda. However, it needs to be questioned whether simply mixing students of different backgrounds in a group necessarily leads to them working collaboratively with each other. Challenges and negative perceptions of the experience have been repeatedly reported in the literature (Summers & Volet, 2008; Turner, 2009). However, most studies in this area were conducted by academic staff who were researching their own students, which might affect how students report their experiences. Additionally, there is little research focusing on intercultural skills development within student groups. By taking a "from students, for students, and about students" stance, I will address this research gap, not only by looking at students' perceptions of their multicultural groupwork experience, but also by looking into the development of transferable skills. My research also addresses factors that influence students' attitudes in order to identify possible actions to foster a better intercultural learning environment. A mixed methods approach was adopted to answer my research inquiry, via two questionnaires involving 286 respondents and two rounds of interviews involving 19 participants, which were conducted at the early stage and end stage of a master's degree course. Both quantitative and qualitative data were collected about postgraduate students' attitudes towards multicultural groupwork, their perceptions of the groupwork experience and how they coped with the difficulties they encountered in the process. While the quantitative findings indicated that overall postgraduate students showed no change of attitudes during their one-year course of study, they largely recognised the benefits and value of working in multicultural groups. The qualitative analysis allowed a deeper exploration of the quantitative findings, for example, elaboration on the difficulties they voiced and challenges they had to deal with. Participants in this study nonetheless confirmed that they did develop skills through working in groups, as well as many creative coping strategies to deal with difficulties that happened during the groupwork process, such as different levels of language proficiency and different working styles. The implications of the study are that further support by academic teaching staff and university administration is needed to promote intercultural awareness and provide intercultural skills training to help students understand culturally different communication and working styles before they undertake group projects. The findings also suggest that current assessment criteria, which largely focus on the end product of multicultural group work rather than the process, should be changed, as the true value of working in multicultural groups exists in the interaction of students studying collaboratively.

Extended school non-attendance (ESNA) is presented in the literature as a difficulty that can result in negative outcomes for the pupil, not only with regard to academic attainment but mental health difficulties, relationship problems and reduced future prospects. In the political context of increased legislation regarding the requirements for pupils be in receipt of suitable educational provision, a legal discourse of ESNA has become entrenched. This sits alongside a dominant clinical discourse which positions school non-attendance as a within child, medicalised construct. Whilst early research aligned extended non-attendance with anxiety, subsequent findings have constructed such attendance difficulties as multi-factorial, interactive and individual. In the existing research, there is little which includes the pupil voice to examine their construction of the attendance difficulty. This qualitative exploration therefore, aimed to examine the construction of the reasons for ESNA by the pupils, parents and school staff, through examining the discourses of participants. The findings of the analysis highlighted the heterogeneity of ESNA and are illustrative of the disparate constructions of the participant groups. The results are discussed in the context of the current literature and the implications of the findings are considered in terms of strategic prevention, identification and intervention of attendance difficulties.

The ensuing thesis is the result of an in-depth interrogation of the following research question: What are the school experiences of LGB,T youth? Despite much research on homophobic bullying in school, little is known about how power intersects and prolongs a bullying event after the initial victimization is over. This study sheds a light on this issue, examining how LGB,T youth understand bullying, their capacity within individual events, while uncovering how power shapes a bullying incident. The first part of the thesis forms the central argument demonstrating key principles underpinning challenges sexual minority youth face while at school. Interrogating political and neoliberal influences, this thesis introduces young people’s stories through multiple lenses. This thesis uncovers schools ineffectual use of inclusion policy revealing policy and practice are failing young people. Furthermore, LGB,T young people’s human rights are also largely overlooked in policy practice. Not treated as having the same rights as other students interferes with their education, and therefore, their human rights. The first two chapters are grounded in present literature as demonstrated in chapter three, which is followed by methodologies in chapter four, rounding out the first section. Chapters five through seven establish the second part of this thesis. Here the reader is introduced to young people’s accounts unpacking bullying incidents. Introducing critical incidents revealed through narrative inquiry, leads to an interrogation of bullying and how power punctuates, intersecting a single event. While chapter eight concludes this thesis. Up to thirty young people participated in sessions, ranging in ages from sixteen to nineteen. Eighteen filled out a questionnaire, while surveys ranged from eight to seventeen participants. Eighteen participated with the one-to-one interview lasting from 30 to 60 minutes. Interviews revealed all young people had experienced bullying at school while several were severely physically bullied and harmed. Girls reported experiencing and identifying bullying differently than boys, while boys reported struggling with homophobic bullying representing their lost male privilege suggesting girls and boys experienced, perceived and defined bullying and power differently. Results revealed not everything defined as bullying, is understood as such. Additionally, power exerted onto the victim during a bullying incident came from multiple sources. First, it came rom the initial attacker then moved to the teacher attempting to resolve the incident, and then to the administration. How they interrogated bullying informed and prolonged a bullying incident long after the initial event ceased. This thesis will reveal how bullying is understood and addressed in schools is ineffective due to its universal ideology considering all experience as the same, and is faulty.

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Thesis (doctoral)--Rheinische Friedrich-Wilhelms-Universität zu Bonn, 1999.