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    19918 research outputs found

    Domestic and international performance of UK SMEs: resources and market learning effects

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    This thesis examines jointly the domestic and international market activities of United Kingdom (UK) small and medium-sized enterprises (SMEs). The study seeks to extend the foundational arguments of international business and international entrepreneurship on differences between domestic and international market activities. It is shown that despite its foundational nature, this theme has received limited and fragmentary research attention. Moreover, none of the theme-related studies identified had applied the resource-based view (RBV) to explain performance, despite the fact that performance is a construct of fundamental research interest and the RBV largely guides management inquiry into the performance determinants. Drawing on the RBV, this research seeks to make a unique contribution towards the holistic understanding of firm performance by uncovering the effects of domestic and international firm resources and market learning on both domestic and international performance. This research pursues a positivist and mixed-method approach, combining qualitative case studies and a large-scale quantitative survey on UK SMEs. The qualitative research phase consists of six case studies, whereas the quantitative phase is based upon a sample of 307 SMEs. The statistical technique of linear multiple regression analysis is employed to analyse this sample and discover whether the hypotheses of this research are supported. The quantitative phase is central and the qualitative phase aims at pre-understanding and facilitating the research process. Hence, the case study research assists the hypothesis development and the interpretation of the survey findings in retrospect. The findings of this research have significant implications for theory and practice. Firstly, domestic and international resources and market learning are found to influence positively domestic and international performance, respectively. A valuable finding for future research on firm market learning processes is that these resources effects seem to be much stronger than the respective market learning ones. Secondly, international resources are found to have a lesser impact on domestic SME performance compared to the effects of domestic resources on domestic performance. Respectively, domestic resources are indicated to have a lesser impact on international performance. Conversely, the equivalent effects of market learning are not established. Lastly, it is intriguing that: a. a positive relationship between domestic resources and international performance is not supported; and b. a negative relationship between international resources and domestic performance is partially supported. These contributions provide a fuller understanding of the complex relationship between domestic and international market activities, and should stimulate further research on this important theme

    Studies of Magnetic Optical Activity in Raman Scattering

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    This thesis consists mainly of theoretical and experimental studies in Magnetic Raman Optical Activity (M.R.O.A.), although the main theoretical result also allows general deductions to be made about conventional vibrational Raman scattering. The main new experimental result presented in the thesis is the discovery of the phenomenon called Raman Electron Paramagnetic Resonance, which is a new category of vibrational M.R.O.A., involving scattering by degenerate ground state molecules. The main objective of the theoretical research was to apply the general magnetic optical activity expressions to explain the spectral features obtained for molecules exhibiting the effect. The main tool used for doing this was Irreducible Tensor Methods. The theoretical framework developed falls naturally into two parts, one for molecules having a non-degenerate ground state, and one for molecules having a degenerate ground state. For the former case, general formulae were obtained for the perturbed and unperturbed polarizability tensor patterns. These allow all the scattering parameters of interest to be calculated. They also allow very general deductions to be made about the form of the M.R.O.A. spectra for various classes of normal mode, along with information about the frequency dependence of M.R.O.A. General conclusions concerning the conditions under which non-degenerate molecules should exhibit signifigant M.R.O.A. are also deduced. For the latter, irreducible tensor methods were used to obtain general expressions for the polarizability tensor patterns. These show that all degenerate ground state molecules satisfying certain conditions should exhibit Raman E.P.R., and facilitate the calculation of detailed tensor patterns for specific molecules. These results are then applied to explain the form of the spectra of various types of molecule which have exhibited M.R.O.A

    Some Observations on Chronic Nasal Disorders in the Dog

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    A retrospective study of sixty cases of canine nasal neoplasia seen at The University of Glasgow Veterinary School between 1983 and 1985 reached the following conclusions: There was no breed predilection; medium to large mesaticephalic dogs were the most commonly affected; the mean age was 9. 2 years; there was no sex predisposition; a wide variety of clinical signs was observed, no single one being pathognomonic; carcinomas were more frequent than sarcomas, adenocarcinomas being the most common. The radiographic features of nasal neoplasia seen on the dorso-ventral intra-oral view were - increased radiopacity together with turbinate destruction although six out of sixty cases did not follow this pattern; vomer erosion and septal deviation were highly suggestive of neoplasia; mineralisation was also indicative of neoplasia but was not typical of any one tumour type. These findings were related to the literature reviewed. A prospective study of twenty clinical cases of chronic nasal disorders in the dog seen between October 1985 and May 1986 concluded the following:- Radiography was the single most useful aid to diagnosis; rhinography provided little additional information; endoscopic examination was useful predominantly in destructive rhinitis and intra-nasal foreign bodies, an alternative to an endoscope would be a large bore auroscope. None of the biopsy techniques utilized were 100% reliable; treatment of aspergillosis with topical enilconazoie achieved good results

    Investigations of the Physical and Magnetic Microstructure of CoCr Thin Film Perpendicular Magnetic Recording Media

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    The work presented in this thesis is concerned with improving the understanding of the relationship between the physical and magnetic microstructure in CoCr thin film perpendicular magnetic recording media. This was investigated using a combination of transmission electron microscope (TEM) techniques to study a series of CoCr films with systematically adjusted growth conditions. The first chapter begins with an outline of basic ferromagnetism and the energy considerations governing the domain configuration in ferromagnetic thin films. General principles of magnetic recording are then discussed, with a more detailed treatment of media, high density recording formats and the properties of CoCr for perpendicular recording. Chapter 2 introduces basic TEM imaging theory and describes the conventional transmission electron microscopes (CTEM's) and the dedicated scanning transmission electron microscope (STEM) used in this project. The chapter then discusses techniques for imaging magnetic structures and the use of high resolution energy dispersive x-ray (EDX) microanalysis in the STEM for microcompositional investigations. The first sections in chapter 3 discuss the planar and cross-sectional specimen preparation techniques adopted for all the work in this thesis. The remainder of the chapter describes the study of a series of CoCr layers grown to various thicknesses and with different compositions. Bulk physical and magnetic characterisation are combined with microstructural investigations in the CTEM. The work demonstrates that bulk measurements alone are insufficient to predict the physical, and therefore the magnetic microstructure, of CoCr thin films. It also illustrates the usefulness of such a study as part of any investigation of the microscopic properties of CoCr recording media. The next three chapters contain the experimental results which form the core of the thesis. Chapter 4 describes the experiments conducted on CoCr films using EDX microanalysis. Planar sections were investigated to allow correct positioning of the probe on a particular region of specimen and thus reveal, directly, the local elemental composition associated with features of the microstructure. Study was made of films deposited at different substrate temperatures both with and without a Ge underlayer. The results obtained using this technique provided detailed quantitative data on the extent and pattern of Cr segregation in each film. Chapter 5 describes the improvements in the differential phase contrast (DPC) mode of Lorentz microscopy in the STEM which facilitated simultaneous imaging of the physical and magnetic microstructure of thinned cross-sections of CoCr films. The results from the application of this technique to the study of the effect on the microstructure of substrate temperature during deposition are then interpreted in conjunction with the compositional information from chapter 4. The importance of direct microscopic study of recorded tracks in CoCr perpendicular recording media forms the introduction for chapter 6. The chapter then explains the development and results of a successful method for direct observation of the tracks with the Fresnel mode of Lorentz microscopy in the JEOL 2000FX TEM. The final chapter draws conclusions on the results of the project and presents proposals for possible future investigations of CoCr perpendicular magnetic recording media

    The Influence of Methimazole and Its Putative Metabolites on Human Polymorphonuclear Leukocyte Function

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    An uncommon side effect of treatment with antithyroid drugs is agranulocytosis. These compounds are also known to be capable of modifying immune function in humans. The polymorphonuclear leukocytes are responsible for clearing invading foreign bodies from the bloodstream, and as such are the first line of defence against infection. The effect of methimazole, a thioureylene antithyroid drug commonly used in the treatment of hyperthyroidism, on selected parameters of polymorphonuclear leukocyte function, was investigated. Methimazole is metabolised by polymorphonuclear leukocytes, therefore the influence of some of its putative metabolites, namely 3-methylthiohydantoin, methylhydantoin and N-methylimidazole, was also assessed. The chemotactic, phagocytic and cidal capabilities of human polymorphonuclear leukocytes were examined. The ability of polymorphonuclear leukocytes to migrate under agarose towards the chemo-attractant, zymosan-stimulated serum, was found to be unaffected by methimazole, 3-methylthiohydantoin, methylhydantoin and methylimidazole at concentrations between 10-3 and 10-7 M. Phagocytosis of S, aureus, S. pyogenes, E. coli, L. casei and C. albicans proceded normally in the presence of 10-3 M methimazole, S. pyogenes and S. aureus, as representatives of hydrogen peroxide- and non-hydrogen peroxide producing bacteria respectively were the subject of further investigation which established that methimazole, 3-methylthiohydantoin, methylhydantoin and N- methyliraidazole did not significantly affect their ingestion at concentrations between 10-3 and 10-5M. Intracellular killing of all five pre-opsonised microorganisms by human polymorphonuclear leukocytes treated with 10-3M methimazole was stimulated by between ten and 40 per cent after 30 minutes co-incubation. Between 60 and 120 minutes there was no evidence of any significant stimulation. Further investigation with S. pyogenes and S. aureus revealed that methimazole, 3-methylthiohydantoin, methylhydantoin and N-methylimidazole exerted no significant effect on the killing of S. pyogenes, however dose-related inhibition was evident on treatment with between 10 and 10-5M methimazole and 3-methylthiohydantoin during phagocytosis of S. aureus. Methylhydantoin and N-methyl-imidazole produced no significant effects. The oxygen consumption of latex-stimulated polymorphonuclear leukocytes was found to be stimulated by 48 and 58 per cent respectively by methimazole and N-methylimidazole at 10 M, 3-methylthiohydantoin and methylhydantoin producing no significant change. The hexose monophosphate shunt activity of similarly stimulated polymorphonuclear leukocytes significantly increased by up to 20 per cent in the presence of methimazole, 3-methylthiohydantoin and N-methylinidazole. None of the compounds exerted any influence on the release of lysosomal enzymes by stimulated polymorphonuclear leukocytes, however methimazole, 3-methylthiohydantoin and N-methylimidazole inhibited myeloperoxidase activity by between 36 and 100 per cent at 10 14, this inhibition was dose-related at concentrations between 10-3 and 10-5M. Lysozyme and lactoferrin activity from the released lysosomal enzymes was unaffected by any of the four compounds, neither was the lysozyme activity of intact polymorphonuclear leukocytes. Alkaline phosphatase activity however was inhibited by around 50 per cent by methimazole and 3-methyl- thiohydantoin at concentrations of 10-3 M; again the inhibitory effect was significantly dose-related. Thus it would appear that methimazole acts, not by inhibiting the microbicidal oxidase system, as might have been expected, but by altering myeloperoxidase activity. (Abstract shortened by ProQuest.)

    The Seven Readings of the Qur'an: A Critical Study of Their Linguistic Differences

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    This thesis is intended as an attempt at a general investigation of the different linguistic features involved in the seven readings. It falls into eight chapters and a general conclusion. At the outset of the thesis, a list of the Arabic technical words is provided with their English equivalents. This is followed by a preface about the topic, its importance, the methods adopted in the thesis, and the main references. Chapter one gives the historical background of the Qur'an, its collection, its seven readings, and the seven readers. Chapter two deals with readings involving variations in siyagh, such as person, gender, number, tense, mood. etc. Index i provides a list of all readings involving siyagh variations . Chapter three deals with readings reflecting elements of lughat variation. Index ii provides a list of all readings involving lughat variations . Chapter four deals with readings involving nahw variation. Index iii provides a list of all readings involving nahw. Chapter five deals with readings involving some aspects of balagha. Index iv provides a list of all readings involving balagha. Chapter six deals with readings involving variations in nazm. Index v provides a list of all the nazm variations. Chapter seven deals with readings deriving from the different Uthmanic codices. Index vi provides a list of all the rasm al-mushaf variations. Chapter eight deals with readings involving variations in macna. Index vii provides a list of all readings involving differences in macna. The general conclusion at the end of the thesis covers all eight chapters

    A Study of the Factors Which Affect the Growth of Tumour Cells at Distant Sites

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    The aim of this thesis is to investigate some of the factors which affect the growth of metastasising cells at distant sites. Previous experiments, mostly involving intravenous injection of cultured murine B16 melanoma and other tumour cell lines, have suggested that subpopulations of cells exist within tumours which are capable of metastasis, sometimes to specific organs. One criticism of these studies is that growth at a distant site is but one characteristic required for a cell to successfully form a metastatic deposit. The cell must also express other phenotypic characteristics such as motility and invasion and in some cases evasion of host defences. Much of the experimental work in this thesis makes use of the B16 melanoma F10 and F1 cell lines. The F10 cell line was derived many years ago by repeated in vivo passage through the lungs of syngeneic mice while the F1 cell line was passaged in vivo only once and has been maintained exclusively in vitro. In this study it was found that the F10 cell line formed tumours at a high rate, exclusively in the lungs, whereas the F1 cell line was much less metastatic and selective in its site of growth. The use of radio-labelled cells showed that the F10 cells were more avidly trapped in the lungs than the F1 cells but the difference in lung trapping between the two cell lines was less marked than the difference in lung tumour formation. These results broadly confirm the results of earlier studies and show that despite prolonged culture the cell lines have been stable with respect to these properties. In contrast to the results of intravenous injection, when F1 and F10 cells were injected into the peritoneal cavity it was found that there was no difference in the number of tumours produced. Each cell line was then subjected to repeated intraperitoneal passage to see whether passaged cells formed more local tumours when injected peritoneally, whether such cells would home to the peritoneal cavity following intravenous injection, and if passage in the peritoneum would effect lung homing properties particularly of the F10 cell line. After 16 passages an F10 cell line was produced which grew more readily in the peritoneal cavity but did not produce abdominal tumours when injected intravenously: lung tumour formation was unaffected. When F1 cells were passaged it was found that after 8 passages cell growth in vitro and in the peritoneal cavity was so greatly reduced that in only one of three sets of experiments was it possible to proceed beyond the eighth passage. The set of F1 cells which reached passage 16 continued to show poor growth in vitro and after intraperitoneal injection but surprisingly produced a much larger number of lung tumours following intravenous injection than the parent cell line. This latter change was not accompanied by increased cell trapping in the lungs. By way of comparison a benign virus-induced salivary tumour was studied. This model was limited by failure to culture the tumour cells in vitro. When a cell suspension derived from this tumour was injected intraperitoneally no tumours resulted. Thus the benign nature of this tumour may have been partly due to an inability to grow at a distant site. An attempt was made to correlate adhesion of B16 and salivary tumour cells to tissue sections with their sites of growth but in contrast to previous studies no such correlation was found. Mechanisms to account for these results are discussed with particular reference to the effects of selection, trapping by the vasculature and the influence exerted by local tissue environments on tumour cells. While these mechanisms are often difficult to separate experimentally there was some evidence that local environments may play a larger part than hitherto realised in controlling the growth of metastasising tumour cells. Little is known of the molecular basis of tumour cell metastasis, though attempts to identify cell surface proteins and more recently the genes involved in the process have met with some success. Since the histo-compatability proteins are known to participate in a wide range of cellular interactions, they may be involved in the process of metastatic tumour growth. (Abstract shortened by ProQuest.)

    Catalysed Reactions

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    Abstract Not Provided

    Investigations of Etomidate and Propofol for the Induction and Maintenance of Anaesthesia

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    Because of the hazards of inhalational agents to both patients and theatre staff, investigations of the hypothesis that total intravenous anaesthetic techniques might provide equally satisfactory anaesthesia for patients either breathing spontaneously or requiring mechanical ventilation compared with conventional inhalational based techniques were carried out. A review of the literature suggested that etomidate and later propofol might be suitable agents for this purpose. The investigations were carried out in two stages. Firstly their properties as induction agents were investigated to determine their potential suitability for infusion. After these studies were completed, the infusion studies were carried out. Supplementary analgesia was provided by the infusion of fentanyl

    Characterisation of Herpes Simplex Virus Type 1 ts Mutants Which Have Structural Defects

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    Four temperature-sensitive DNA+ mutants, ts1201, ts1203, ts1204 and ts1208, each of which contain a lesion in HSV DNA fragment EcoRI f (mu 0.312-0.415), have been characterised in this study. Ts1204 has a temperature-sensitive lesion located within a 400bp region between mu 0.322-0.324 on the HSV genome. This mutant adsorbed normally to the cell surface at the NPT, but failed to penetrate the cell membrane. Ts1204 appeared to bind to specific cellular receptors for HSV-1, since high multiplicities of infection of the mutant blocked subsequent superinfection of cells by HSV-1, but not by HSV-2. The penetration defect could be overcome either by brief incubation of ts1204-infected cells at the PT before temperature upshift to the NPT, or by treatment of the cells with polyethylene glycol, a compound which promotes fusion of membranes. Upon continued incubation of mutant virus-infected cells at the NPT, low numbers of capsids were assembled. Although these capsids contained some internal structure, they did not contain DNA. Another mutant, ts1208, lies in the same complementation group as ts1204. This mutant penetrated cells normally at the NPT but, like ts1204, assembled low numbers of capsids which did not contain DNA. Marker rescue experiments mapped the ts1208 lesion to the left of the ts1204 lesion, within BamHI u. The ability of high multiplicities of ts1204 to block superinfection of cells by HSV-1 but not by HSV-2 was utilised to determine the virus polypeptides involved in the recognition of specific cell surface receptors. A series of intertypic recombinant viruses, which induced both HSV-1- and HSV-2-specific envelope glycoproteins, were all found to be capable of penetrating cells previously infected with ts1204 at the NPT. This result suggests that the virus attachment complex may be composed of more than one glycoprotein, and that a mixture of both HSV-1 and HSV-2 glycoproteins are able to recognise and bind to cellular receptors specific for HSV-2, since no HSV-2 sequence was common to all recombinants. The alternative explanation that the recombinants contained undetected crossovers cannot, however, be ruled out. Ts1203 has a ts lesion which maps in a 450bp fragment located between mu 0.377-0.380 on the HSV-1 genome. This mutant assembled large numbers of capsids at the NPT, but failed to encapsidate DNA. In this respect ts1203 resembled ts1201, a mutant which lies in a different complementation group but also has a defect in packaging of virus DNA into capsids (Preston et al., 1983). At the PT, DNA encapsidation was less efficient in ts1203-infected cells than in wild-type virus-infected cells. In addition, the defect in ts1203 appeared to be irreversible upon temperature downshift in the absence of further protein synthesis. Greater than 99% of the DNA synthesized in both ts1203- and ts1201-infected cells at the NPT was endless, suggesting that the unpackaged mutant virus DNA remained in a concatemeric form. Complementation experiments, using other ts mutants which had lesions in HSV DNA fragment EcoRI f, showed that ts1203 represents a novel complementation group. In preparation for DNA sequencing experiments to determine the base change responsible for the ts1203 phenotype, the DNA fragment containing the ts1203 lesion, and the corresponding fragment from ts1203 rev-1, a spontaneous revertant of ts1203, have been cloned into plasmid vector pUC9. Preston et al. (1983) demonstrated that ts1201 failed to process the polypeptide p40 to its lower molecular weight forms at the NPT. This result, together with the earlier observations by Gibson and Roizman (1974), strongly suggested that p40 was involved in the virus DNA encapsidation process. In contrast to ts1201, however, ts1203 was found to process p40 correctly at the NPT. Immune electron microscopic experiments showed that p40 was associated with both ts1203 and ts1201 empty capsids at the NPT. Experiments were performed to investigate the reason for the failure of p40 to be processed correctly in ts1201-infected cells at the NPT. It was found that the high MW forms of p40 were translocated normally from the cytoplasm to the nucleus in these cells. It was also shown that p40 synthesized in cells infected with HSV-1 strain 17 syn+ was not phosphorylated to any detectable extent, in contrast to results obtained with other HSV-1 strains (Heilman, 1979; Braun et al., 1984). Thus, defects in either of these events are unlikely to be responsible for the failure of p40 to be processed correctly to its lower molecular weight forms in ts1201-infected cells at the NPT


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