• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 118
  • 52
  • 51
  • 49
  • 20
  • 19
  • 16
  • 8
  • 8
  • 7
  • 7
  • 5
  • 4
  • 3
  • 3
  • Tagged with
  • 376
  • 84
  • 51
  • 37
  • 35
  • 34
  • 34
  • 32
  • 30
  • 28
  • 27
  • 26
  • 26
  • 25
  • 22
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

An Investigation of Migraine Candidate Genes and Genomic Susceptibility Regions

Lea, Rod A., n/a January 2003 (has links)
Typical migraine, comprised of migraine with aura (MA) and migraine without aura (MO), is a chronic, painful and debilitating neurovascular disease which is generally characterised by recurrent attacks of severe headache usually accompanied by nausea, vomiting, photo and phonophobia. Migraine has been shown to affect a large proportion of Caucasian populations with a recent comprehensive study indicating that around 25% of women and 8% of men suffer from the disease. Strong familial aggregation of typical migraine and an increased concordance for the disease in MZ twins over DZ twins, suggests that it has a significant genetic component. Heritability estimates are calculated to be between 40% and 60%, indicating that disease variation, in part, is explained by environmental determinants. The mode of transmission of typical migraine is not clear but is most likely multifactorial. Although the MA and MO subtypes exhibit some clinical heterogeneity, segregation analysis has suggested that there may be a common genetic aetiology for MA and MO, and a major gene contributing to typical migraine pathogenesis. This idea is substantiated by the fact that both subtypes of migraine can occur within the same family and even within the same individual, with up to 33% of sufferers experiencing both types of the disease. In addition, migraine prophylactics have been shown to result in similar effects in patients treated for both types of migraine. However, whether the two subtypes are truly separate entities or not remains unclear. At present, the type and number of genes involved in typical migraine is not known. Despite this, several studies into Familial Hemiplegic Migraine (FHM), a very severe subtype of MA, have led to the discovery that mutations in a brain specific calcium channel subunit gene (CACNA1A) located on chromosome 19, cause FHM in about 50% of affected families. FHM is a rare disease and is distinguished from typical migraine by its association with hemiparesis and clear autosomal dominant mode of inheritance. However, certain clinical features are common to both FHM and typical migraine including similarities in headache characteristics and triggers. Hence, FHM genetic studies provide a valuable model for investigating the genes involved in the more prevalent types of migraine with and without aura. For this reason the Genomics Research Centre has been conducting linkage studies utilising large Australian migraine pedigrees with a focus on the known FHM (CACNA1A) gene region on chromosome 19p13. Our results to date have indicated suggestive linkage to the FHM region on 19p13 in a large multigenerational pedigree (MF1) affected with typical migraine, with a maximum parametric LOD score of 1.92 (P = 0.001) obtained for a triplet repeat polymorphism situated in exon 47 of the CACNA1A gene. Expansion of this repeat was not observed, but is possible that mutations elsewhere in the CACNA1A gene may be responsible for migraine in this pedigree. To investigate this possibility, the current research involved sequencing two patients carrying the critical susceptibility haplotype surrounding the CACNA1A gene. The results of this mutation screen revealed no disease causing mutations or polymorphisms in any of the 47 exons screened. To determine whether the CACNA1A genomic region was implicated in typical migraine susceptibility in the general Caucasian population, 82 independent pedigrees and a large case-control group were also analysed using highly polymorphic microsatellite markers. There was no linkage or association detected in these groups and thus, it was concluded that if CACNA1A plays a role in typical migraine it does not confer a major effect on the disease. However, subsequent case-control studies of SNPs in the INSR gene, which is located ~15cM telomeric from CACNA1A, provided evidence of association to typical migraine. Thus, the INSR gene may now emerge as the new migraine susceptibility gene in this genomic region on chromosome 19. Family linkage studies conducted by Gardner et al have implicated an additional FHM susceptibility region on chromsome 1q31. Furthermore, independent research carried out by Ducros et al. has indicated a second FHM locus at 1q21-23, which is ~ 30cM centromeric to the region reported by Gardner et al. At this stage it is not clear whether there is a single locus, or two distinct loci, on the chromosome 1q region. This research also involved a family-based linkage and association approach to investigating the FHM susceptibility region on chromosome 1q31 for involvement in typical migraine susceptibility in affected Australian pedigrees. Initial multipoint ALLEGRO analysis provided strong evidence for linkage of Chr1q31 markers to typical migraine in a large multigenerational pedigree. The 1-LOD* unit support interval for suggestive linkage spanned ~18cM with a maximum allele sharing LOD* score of 3.36 obtained for marker D1S2782, P = 0.00004. Subsequent analysis of an independent sample of 82 affected pedigrees added support to the initial findings with a maximum LOD* of 1.24 (P = 0.008). Utilising the independent sample of 82 pedigrees we also performed a family-based association test. Results of this analysis indicated distortion of allele transmission at marker D1S249 (global c2(5) of 15.00, P = 0.010) in these pedigrees. These positive linkage and association results will need further confirmation by independent researchers, but overall they provide good evidence for the existence of a typical migraine locus near these markers on Chr1q31, and reinforce the idea that an FHM gene in this genomic region may also contribute to susceptibility to the more common forms of migraine. The serotonergic system has long been implicated in the pathophysiology of migraine. Researchers have therefore focused on the serotonin receptors and the genes that code for them when investigating this disease. Although serotonin receptor agonists have proven to be effective in the treatment of migraine, there has been little evidence of a serotonin receptor gene being associated with the disorder. However, in 1998, Ogilvie et al reported that a VNTR in the serotonin transporter gene (SERT) showed altered allelic distributions in a Danish migraine population. In addition to serotonin, there has been renewed interest in the involvement of the dopaminergic pathways in migraine. This interest has gained impetus since the study of Peroutka et al who reported an allelic association between the dopamine receptor gene DRD2 and migraine with aura. Another dopamine related gene, the dopamine beta-hydroxylase gene (DBH), has been localised to Chr 9q34 and codes for the enzyme that catalyses the conversion of dopamine to norepinephrine. It therefore plays an important role in dopaminergic and noradrenergic neurotransmission. Serum levels of DbH enzyme have been reported to be elevated in migrainous patients during the headache phase of an attack. Also, significantly increased DbH enzyme activity has been observed in migraine patients during the headache-free interval. Thus, the DBH gene is another good candidate for involvement in migraine pathophysiology and, to our knowledge, has not been previously implicated in this disease. Candidate gene studies may be useful strategies for identifying genes involved in complex diseases such as migraine, especially if the gene being examined contributes only a minor effect to the overall phenotype. This research also involved a linkage and association approach to investigating neurotransmitter related migraine candidate genes. Specifically, polymorphisms within the serotonin transporter gene (SERT), the dopamine receptor gene (DRD2) and the dopamine beta-hydroxylase (DBH) gene were tested in unrelated Caucasian migraineurs and non-migraine control individuals. In addition, an independent sample of 82 families affected with migraine were examined. Unrelated case-control association analysis of a DBH intragenic dinucleotide polymorphism indicated altered allelic distribution between migraine and control groups (c2 = 16.53, P = 0.019). Furthermore, the transmission/disequilibrium test (TDT) which was implemented on the family data also indicated distortion of allele transmission for the same DBH marker (c2 = 4.44, P = 0.035). Together, these results provide evidence for allelic association of the DBH gene with typical migraine susceptibility (Fisher's Combined P-value = 0.006) and indicate that further research into the role of the DBH gene in migraine aetiology is warranted. Nitric oxide (NO) is emerging as a key molecule affecting the pain associated with migraine. Since nitric oxide synthase (NOS) enzymes catalyse the synthesis of NO, the genes that code for these enzymes are good candidates for migraine molecular genetic analysis. This research involved investigating the role of a functionally relevant bi-allelic tetranucleotide polymorphism located in the promoter region of the human inducible nitric oxide synthase (iNOS) gene in migraine aetiology. A large group of migraine affected individuals were genotyped and compared to an age and sex matched group of unaffected controls. Results of a chi-squared analysis indicated that allele distributions for both migraine cases and controls were not significantly different (c2 = 1.93, P = 0.16). These findings offer no evidence for an allelic association of the tested iNOS polymorphism with the common forms of the disease and therefore do not support a role for this gene in migraine pathogenesis. In summary, this research involved linkage and association analysis of migraine candidate genes and genomic susceptibility regions. Whilst, the known FHM gene (CACNA1A) was excluded for significant involvement in typical migraine the adjacent INSR gene has been associated. Migraine is genetically heterogeneous and the results of this research also provide good evidence that the DBH gene is involved in disease predisposition, whilst the DRD2, SERT and INOS gene were not shown to be implicated. An additional susceptibility region for typical migraine is also likely to localise to chromosome 1q31. Overall, the results presented in this thesis have contributed valuable data to the understanding of the molecular genetics of migraine with and without aura. Future research into the molecular pathophysiological mechanisms of migraine will greatly facilitate the development of more effective diagnosis and treatment strategies.
62

Modelling, Simulation and Optimisation of Asymmetric Rotor Profiles in Twin-screw Superchargers

Ilie, Katherine-Rodica, Katherine.ilie@rmit.edu.au January 2007 (has links)
There is a growing recognition worldwide of the need for more powerful, smaller petrol engines, capable of delivering the higher picking power of larger engines, yet still being economical and environmentally friendly when used for day-to-day driving. An engineering solution for more efficient engines has been considered by research so far. It has been identified that superchargers can potentially improve the performance of automotive engines; therefore research has focused on developing superchargers and supercharger components with higher efficiency. Of particular interest to the research presented in this thesis has been the twin-screw supercharging compressor with design adapted for automotive use (the twin-screw supercharger). The performance of this supercharger type depends on the volume and total losses of the air flow through the supercharger rotors more than on any other aspects of its behaviour. To accurately predict the efficiency of the twin-screw su percharger for matching a particular engine system, accurate supercharger design is required. The main objective of this research was the investigation of the existing limitations of twin-screw superchargers, in particular leakage and reduced efficiency, leading to the development of optimal asymmetric rotor profiles. This research has been completed in four stages defining an innovative rotor design method. The parametric three-dimensional geometric model of twin-screw supercharger rotors of any aspect ratio was developed. For model validation through visualisation, CAD rotor models with scalable data were generated in commercial CAD software and calibrated experimentally by Laser Doppler Velocimetry (LDV) tests. Calibrated rotor profile data can be transferred into CAD-CFD interface for flow simulation and performance optimisation. Through the application of this new rotor design method, new opportunities are created for the twin-screw supercharger design practice, making it a part of the engineering solution for more efficient engines.
63

Turbulent Premixed Flame Kernel Growth During The Early Stages Using Direct Numerical Simulation

Dunstan, T. D. January 2008 (has links)
In this thesis Direct Numerical Simulation (DNS) is used to investigate the development of turbulent premixed flame kernels during the early stages of growth typical of the period following spark ignition. Two distinct aspects of this phase are considered: the interaction of the expanding kernel with a field of decaying turbulence, and the chemical and thermo-diffusive response of the flame for different fresh-gas compositions. In the first part of the study, three-dimensional, repeated simulations with single-step chemistry are used to generate ensemble statistics of global flame growth. The surface-conditioned mean fluid-velocity magnitude is found to vary significantly across different isosurfaces of the reaction progress variable, and this is shown to lead to a bias in the distribution of the Surface Density Function (SDF) around the developing flame. Two-dimensional simulations in an extended domain indicate that this effect translates into a similar directional bias in the Flame Surface Density (FSD) at later stages in the kernel development. Properties of the fresh gas turbulence decay are assessed from an independent, non-reacting simulation database. In the second part of this study, two-dimensional simulations with a detailed 68-step reaction mechanism are used to investigate the thermo-diffusive response of pure methane-air, and hydrogen-enriched methane-air flames. The changes in local and global behaviour due to the different laminar flame characteristics, and the response of the flames to strain and curvature are examined at different equivalence ratios and turbulence intensities. Mechanisms leading to flame quenching are discussed and the effect of mean flame curvature is assessed through comparison with an equivalent planar flame. The effects of hydrogen addition are found to be particularly pronounced in flame kernels due to the higher positive stretch rates and reduced thermo-diffusive stability of hydrogen-enriched flames.
64

A study on the Revealed Patent Advantage and the R&D productivity of IC Design companies

Chou, Cheng-chieh 23 July 2010 (has links)
The Strategies of the firms in Patent are not only about the future, but also forming the barrier for competitor. For the sake, we should develop the patent strategies and technological position.This study goes to the discussion of technological position by the patent multivariate analysis, and suggest the patent strategy by the difference within and between the groups which were clustered from IC design companies. This study selects twenty gobal IC design companies,which are always on the top25 of the industry.In case1 ,we wonder figure out the technological postion and the path of technology shift.In case2,we can recognize the technological position as industrial position. In case 1, we got four clusters by cluster analysis.Cluster 1 is called SpecialistII,and cluster2 is called Strong Generalist, and cluster 3 is called Specialist I,and cluster 4 is called Weak Generalist. For further observation, the firms with technology shift will shift from cluster 1 to cluster 2 in the same direction.Others still maintain the same strategies in their clusters. In case 2 , we also got four clusters by the analysis. Cluster 1 is called Weak Generalist ,and cluster 2 is called Strong Generalist, and cluster 3 is called Specialist I,and cluster 4 is called Specialist III.As financial results , we got homogeneity within a cluster except cluster 4. Performance between clusters, we made and observed the line chart of trend in the selected financial ratio and we used the median of samples within a cluster. In case 2,it seems heterogeneous in ROA and Price-to-book ratio in the chart.In case1,it is also heterogeneous in ROA and price-to-book ratio.It¡¦s significant and positively correlated in R&D productivity(GrossMargin-to-R&D ratio) between others by the correlation coefficient matrix.It seems to be the proxy to the other financial ratio.
65

A Study of the Key Success Factors of Own Brand -- Case Study of DC-FAN Motor Driver ICs Market

Liu, Yu-Ming 31 July 2011 (has links)
Recently, the government makes good an environment and fully support to semiconductor industries from top to bottom covering the wafer foundry, IC design and equipment testing in Taiwan. Therefore, most of semiconductor brands which are very famous in the international. In early stages, Taiwanese electronic makers which were from OEM (Original Equipment Manufacturing, OEM) model to get resources, technologies and market information. They were became designers and have own R & D via the cooperation of international companies. And also got business form ODM (Original Design Manufacturing, ODM) to its own brand (Own Brand Manufacturing, OBM) direct management about the smile curve at both ends of the market to earn profits. In this study, Taiwan's IC design industry point of view of IC critical success factors of its own brand. In addition, to gathering in DC-FAN motor driving circuits in Taiwan. There are two related information of major leading brands for study. Through "qualitative research" in depth interviews of experts within the industry leader for the interview study, to find out its own brand of IC critical success factors. This research through the collation of expert interviews found that the market should impetus to fully service, increase innovative business models and strengthen integrated development of the semiconductor supply chains to get high techniques for next generation of products. And, to make good relationship with high position of customers that is critical success factors in its own brand. Moreover, it is a base of planning new products for the further. Hope, these findings could offer and give suggestion to industries as a reference. There is a model for reference when some one faces to similar situation.
66

Competitive Strategy Study of Taiwan IC Design Company ¡V Taking F Corp. as an Example

Song, Jui-lu 08 August 2005 (has links)
Starting 80¡¦s, Taiwan¡¦s IC design industry has made brilliant achievements so far, ranked as No. 2 in the world , just second only to U.S.A. However in recent years, as competition being fierce day by day, entry barriers such like capital and technology are getting higher and higher which make it more and more difficult to have new star company in the industry. Especially under the major trend of SoC (system on chip), what it will be of the competitiveness of Taiwan¡¦s IC design industry? How the industry should react to the SoC trend? This is what this thesis intend to find out. Moreover, we take F company which is a new IC design company in Taiwan as an example to enrich the study and make it more practical. Through the study of this thesis, we find the SoC trend has impacted Taiwan¡¦s IC design industry definitely. The impacts including not only the higher entry barrier of the industry but also the cooperation structure between system makers and IC design company. In addition, the IC design industry environment has huge change which including medium and small size company will getting harder to survive, the company who focus on technology development only will be less competitive, and participation of China as both of market provider and industry competitor. The impact of the participation of China will expand rapidly, and the one who react with it earlier will get better chance to survive.
67

The green process that¡¦s affect to the packing industry: The study of Orient Semiconductor Electronic,Ltd

Su, Chen-ping 05 February 2006 (has links)
The continuing of industrial revaluation and capitalism today are facing the most difficult enemy ever. 38 billion years of natural resources will be destroyed and over utilized within the next 10 years. The global business will be paying 1500 billion dollars to overcome the effect of changing wheather and natural environment especially those digital industry. The global high tech industry is having a ¡§Green colour¡¨ hits. It is not a war in invoice competition. It is a war for life. The continues of the technological advantages and fast development in industry, have bringing in a convenient life to human being but on the other hand it had introduced lots of troubles in our natural environment. The awareness of our natural environment began in 1970, the first ¡§Global Day¡¨ continues in 1972, Stockholm¡¦s environment and development conference, people begins their awareness of our natural environment, knowledge, understanding and its trouble. In August this year the European alliances will be announcing the three directions of the law in the waste of electrical engineering and facility and electrical facility and products awareness. Therefore the producers have to register their product before August this year. Which includes the digital produce company, products, after sales services and recycling business are all effected bye the law. The following trend of Green Process will be the next demand on industry generation. Under the green process direction, every products that produced have to be recyclable, Lead free, Halogen free . Therefore the trend will bring to a whole new revolution of digital industry. Taiwan¡¦s IC packing industry is one of the most important rule to be a part in global semiconductor. In order to be part of trend, and facing the changing environment, follow the flow is the only way to continue the business. Our aim for this research is to discover the green products¡¦ that¡¦s affect to the packing industry. Our research is hoping to discover a deep underneath for every cases of green process products changing and to the IC packing industry. We also hoping the research could analyze the future development of the green process environment.
68

none

Wang, Ruoh-yun 19 July 2006 (has links)
none
69

The network characteristics of hi tech industries

Tai, Chia-Wen 27 June 2000 (has links)
Abstract Networks are a general feature of Taiwan¡¦s industry. Alongside rapid developments in technology, the island¡¦s industrial structure is being transformed; at the same time, new approaches to administration and management are developing. Hi tech industries are playing a vital role in Taiwan¡¦s economic growth, and this thesis aims to uncover the network characteristics of these industries. The thesis uses the extensive literature available today as the source material for analyzing and comparing the industrial and network characteristics of both traditional and hi tech industries. Three important underlying factors are presented in this thesis; together, these factors help to understand the differences between network characteristics in traditional and hi tech industries. Our research into the characteristics of networks in hi tech industries revealed some interesting results. Firstly, we found that these networks are more elastic, and better able to react to changes in the business environment than traditional networks. Secondly, we discovered that job status in hi tech industries is generally less obvious, more equal and more fluid. Thirdly, existing personal connections still play an important role in hi tech industries, but are less important than in traditional businesses. Networks in hi tech industries have inherited many characteristics of the traditional network; however, as the industrial environment has changed, so networks within hi tech industries have developed many interesting characteristics which differ from traditional industrial networks in important ways.
70

The Study on the Measurement of Out-of-Plane Displacement of an Object Subjected to Both Temperature and Displacement Field by Using the Holographic Interferometry

Tsai, Ming-Lang 17 May 2001 (has links)
The main aim of this study is to extending the holographic interferometry technique to measure the out-of-plane displacement of an object subjected to both temperature and displacement field. It is noted that both the out-of-plane displacement and the ambient temperature change can cause image fringes. Therefore, an auxiliary object is used to identify the fringe numbers caused by the ambient temperature change during the experiment. The warpage measurement of a PBGA package is used as an example. It can be shown that the proposed method works

Page generated in 0.0353 seconds