4,010 research outputs found
SME leaders’ learning in networked learning : an actor-network theory and communities of practice theory informed analysis
No full textThis thesis brings a Communities of Practice perspective together with Actor-network theory to provide a rich understanding of the social learning processes of SME leaders within a networked learning programme. Networked learning as an educational approach is a growing area in higher education. The networked learning programme under investigation forms part of the knowledge exchange initiatives at Lancaster university management school. The research explores the learning process through a qualitative, inductive approach underpinned by an (online and offline) ethnography and is supported by qualitative interviews, the researcher‟s own reflections and other secondary data. The study focuses on three main issues. Firstly, it provides an in-depth understanding of the way a learning community comes together. Secondly, it shows how delegates learn through co-constructing knowledge and the practices within the learning community. It is proposed that the learning community constructs, learns and challenges the situated curriculum. This takes place through the process of legitimate peripheral participation. Gaining fuller participation leads to an increased identification with that of „leader‟. Thirdly, the study theorises four conceptual learning spaces to show where the delegates learn. They are conceived of as an effect of the delegates‟ engagement with the integrated learning model underpinning the networked learning programme. The thesis concludes with a discussion presenting a set of learning and design principles. These can be used to inform the design and thinking around networked learning and knowledge exchange. Combining the theoretical frameworks of Actor-network theory and Communities of Practice theory is unique in the context of exploring the learning processes within networked learning. This combination stretches aspects of the main tenets of each theory and offers contributions to all three theoretical frameworks
Why do students miss lectures? : An exploratory study of a faculty at a post 1992 university
No full textA large number of factors are known to be influential on student absenteeism, but little work has been undertaken into understanding this behaviour at a more conceptualised level. In the UK, it appears that only one small scale study has been undertaken into reasons for absenteeism specifically from lectures, despite the growing concerns about this behaviour. This thesis attempts to both improve understanding of why students miss lectures in a Faculty at a post 1992 university, and to explain this behaviour in a more conceptualised way. Nine attributions categorised using three headings: 'student', `lecture' and `context' are first proposed from which three broad constructs are derived that, it is argued, give meaning to the experience of missing lectures for many students in the Faculty. The three constructs are disinterest, disquiet, and disengagement. Disinterest is about an approach to study and learning in the context of missing lectures and is understood as the 'Can't be bothered' attitude to attending lectures; disquiet is about the affective meaning of students missing lectures and is a 'Don't like it! response to the lecture experience; and disengagement is a rational assessment of lectures as having a low expected gain to the student as a 'What's the point? ' deduction in relation to attending lectures. It is possible that these three constructs allow for a reconstruction of the empirical data within a holistic framework interpreting the behaviour of missing lectures from either an etiological perspective, or from an individual psychoanalytical perspective. Low immediacy, instrumentalism, expectations, isolation, discomfort and goal ambiguity, are argued to be the important influences on disinterest, disquiet and disengagement. This thesis presents empirical evidence supporting disinterest, disquiet and disengagement as important constructs in the student's attendance behaviour, and considers how these constructs might be used to guide future research. The thesis concludes with a discussion of the issues for the Faculty raised by the research
85 W Tm(3+)-doped silica fibre laser
No full textAn 85 W Tm³⁺-doped silica fibre laser is presented. To the best of the authors’ knowledge this is the highest output power achieved by pumping with 793 nm. The slope efficiency was 56%, the threshold 11 Wand the output wavelength centred at 2.04 µm. The high rate of cross relaxation in this laser provided a quantum efficiency of >130%.G. Frith, D.G. Lancaster and S.D. Jackso
Thermal-lens measurement of a quasi steady-state repetitively flashlamp-pumped Cr, Tm, Ho:YAG laser
No full textA simple technique using cavity stability conditions is demonstrated to measure the effective dynamic thermal lensing of a flashlamp-pumped Cr, Tm, Ho:YAG laser operated in a low repetition-rate regime of 4-7 Hz. By measuring the flashlamp energy where a stable resonator becomes unstable, the effective focal length of the laser rod can be calculated. When no mode restricting aperture is used in the cavity, the thermal lens behaviour displays a significant deviation from the commonly assumed thin lens approximation. © 1998 Elsevier Science Ltd. All rights reserved.D.G. Lancaster and J.M. Daweshttp://www.elsevier.com/wps/find/journaldescription.cws_home/30464/description#descriptio
Ho-doped silica fibre laser in-band pumped by a Tm-doped fibre laser
No full textOver the last few years there has been increasing interest in power-scaling of fibre-based sources operating in the eyesafe two-micron wavelength regime driven by a range of applications. Much of this interest has focussed on Tm-doped silica fibres which offer wide spectral coverage from ~1.7 µm to ~2.1 µm [1], a range of pump wavelengths and the potential to be scaled to very high powers [2]. By contrast, far less attention has been directed towards Ho-doped silica fibres which also offer a very wide range of emission wavelengths extending well beyond 2.1 µm
Synthesis optimization and charge carrier transfer mechanism in LiLuSiO<sub>4</sub>:Ce, Tm storage phosphor
No full textLiLuSiO4:Ce and LiLuSiO4:Ce, Tm show very efficient charge carrier storage properties upon beta irradiation after samples have received treatment in vacuum. They outperform the commercial storage phosphor BaFBr(I):Eu2+ in many aspects. The influence of the synthesis conditions, Ce and Tm concentration, nonstoichiometry and codoping with Ca, Hf, Al and Ge are reported. Based on the results of the synthesis optimization, thermoluminescence (TL) emission and TL excitation spectra a mechanism of charge carrier transfer, storage, and recombination during irradiation and thermal or optical readout is proposed.Accepted Author ManuscriptRST/Fundamental Aspects of Materials and EnergyRST/Luminescence Material
2.1 micrometer waveguide laser fabricated by femtosecond laser direct-writing in Ho(3+), Tm(3+):ZBLAN glass
No full textWe report the first Ho 3+ doped waveguide laser, which was realized by femtosecond direct-writing of a depressed cladding structure into ZBLAN glass. Tm 3+ sensitizing allows the 9 mm long Ho 3+ gain medium to be conveniently pumped at 790 nm, achieving an optical-to-optical slope efficiency of 20% and a threshold of 20 mW. The potentially widely tunable laser produces up to 76 mW at 2052 nm and also operates at shorter wavelengths near 1880 nm and 1978 nm for certain cavity configurations.D. G. Lancaster, S. Gross, H. Ebendorff-Heidepriem, A. Fuerbach, M. J. Withford, and T. M. Monr
The value of talent management architectures to multinational companies
No full textThe purpose of this research is to examine the perceptions and understandings of two groups of strategic actors (HR and talent leaders as system designers and business leaders as system implementers) in multinational companies (MNCs). Moreover, to contribute to the knowledge and understanding of how multinational organisations think about and define Talent Management (henceforth shortened to TM) and whether and how they perceive their TM architectures to add value to the organisation. It examines two research questions. First, ‘do strategic actors believe that the TM architectures implemented within their organisations add value to the organisation, and if so, what value do they believe it adds?’ Second, ‘how may TM architectures add value?’ This question is examined through a sub-set of four research propositions in relation to a series of theoretically established value processes (value creation, capture, leverage and protection). The research draws upon ideas from three academic disciplines: Strategic Management and the role of strategic actors and the nature of strategy-as-practice, Strategic Human Resources Management (henceforth shortened to SHRM) and the study of HR systems, High Performance Work Systems (henceforth shorted to HPWS) and TM architectures, and the resource-based view (henceforth shortened to RBV) of the firm in relation to value and value creation - in order to address the problem of value and TM. It develops a series of propositions to suggest how TM architectures might add value through four enabling value processes. The findings are used to draw inferences about these potential value-adding processes. The research uses an 'explanatory' multi-case study design based on an empirical study conducted in five MNCs. The study uses a qualitative research approach, drawing on 52 in-depth interviews. The findings show that the absence of a formal TM definition led to a lack of consensus among strategic actors about the meaning of TM. Instead, there was a common perception that TM is another HR process which includes traditional practices such as the recruitment, selection, development and retention of talent. However, introducing the concepts of ‘value’ to the discourse of TM demonstrated how borrowing notions from the non-HR literature can contribute to our understanding of the role played in TM by strategic actors. The use of a theoretical framework – the value model - helped in understanding the value of TM architectures against each of the four value processes. This study makes a number of contributions. It empirically deconstructs the understandings of strategic actors about TM. It addresses the definitional problem currently evidenced in the literature and provides new insights to help academics understand the value of TM. It provides direction for future research. The study also contributes to practice by providing system designers and system implementers with a blueprint which could guide the design and implementation of the TM architectures introduced in their organisations to ensure that these architectures are aligned to corporate and business strategies and contribute to the enablement of value. Keywords: Talent management, Talent management architectures, Value, Value creation, Value capture, Value leverage and Value protection
Widely tunable short-infrared thulium and holmium doped fluorozirconate waveguide chip lasers
No full textWe report widely tunable (≈ 260 nm) Tm(3+) and Ho(3+) doped fluorozirconate (ZBLAN) glass waveguide extended cavity lasers with close to diffraction limited beam quality (M(2) ≈ 1.3). The waveguides are based on ultrafast laser inscribed depressed claddings. A Ti:sapphire laser pumped Tm(3+)-doped chip laser continuously tunes from 1725 nm to 1975 nm, and a Tm(3+)-sensitized Tm(3+):Ho(3+) chip laser displays tuning across both ions evidenced by a red enhanced tuning range of 1810 to 2053 nm. We also demonstrate a compact 790 nm diode laser pumped Tm(3+)-doped chip laser which tunes from 1750 nm to 1998 nm at a 14% incident slope efficiency, and a beam quality of M(2) ≈ 1.2 for a large mode-area waveguide with 70 µm core diameter.D.G. Lancaster, S. Gross, M. J. Withford, and T. M. Monr
High power 2-micrometers Tm3+-doped fibre lasers
No full textUsing Tm 3+-doped double-clad silica fibre we have produced high power, high efficiency 2μm lasers. To date we have achieved a 59% slope efficiency relative to launched pump power using single end pumping and double passing the pump light. By pumping the fibre laser from both ends, we achieved up to 118W peak output power with 54% slope efficiency relative to launched power at 25% duty cycle. The quantum efficiency of this laser was 120% relative to launched pump power, which we attribute to a cross-relaxation process in Tm 3+ ( 3H 4, 3H 6→ 3F 4, 3F 4). We have also demonstrated fixed wavelength operation of the laser near 1.9μm by using fibre Bragg gratings.Gavin P. Frith, David G. Lancaster and Stuart D. Jackso
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