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  • 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.
21

Identifying Land Use Changes and It's Socio-Economic Impacts : A Case Study of Chacoria Sundarban in Bangladesh

Musa, Khalid Bin January 2008 (has links)
<p>Human intervention and natural phenomenon cause change in land use day by day. Availability of accurate land use information is essential for many applications like natural resource management, planning and monitoring programs. Landuse Change has become a central component in current strategies for managing natural resources and monitoring environmental change. Because of the rapid development in the field of land use mapping, there is an increase in studies of land use change worldwide. Providing an accurate assessment of the extent and health of the world’s forest, grassland and agricultural resources has become an important priority. By printed maps without any statistics or only statistics without any map can not solve this visualization problem. Because printed maps have not attracted as much attention as statistics among the people because of it is limited applications (Himiyama, 2002). Remotely sensed data like aerial photographs and satellite imageries are undoubtedly the most ideal data for extracting land use change information. Satellite images are the most economical way of getting data for different times. The multitude of existing software helps getting information from satellite image also in manipulating the information. The approach used in this study to classify satellite images and change detection based on Satellite images Landsat MSS (1972), Landsat TM (1989) and Landsat ETM (1999) for using supervised classification methods like maximum likelihood (MAXLIKE), MAHALCLASS and time series analysis of CROSSTAB. After performed these hard and soft classifiers the research showed the significant Landuse change in the study area of Chakoria Sundarban mangrove forest. Remote sensing is the modern tools for detecting change pattern and behaviours of coastal environment (Saifuzzaman, 2000). So, those tools are used in the research work for better change analysis of the study area. For analyzing, evaluation and mapping environmental change detection of different years remotely sensed data have been undertaken. The present research provides some suggestions and recommendations as per research findings in order to optimize the utility of coastal resources and to maintain the sustainability of the resources, coastal land use control and there by stabilizing the coastal vulnerable area of chakoria Sundarban.</p><p> </p>
22

PROPRIETES DE TRANSPORT DE MICROSTRUCTURES ET NANOSTRUCTURES DE SILICIUM.

Rochdi, Nabil 07 November 2007 (has links) (PDF)
L'étude porte sur le transport, électronique et de spin, dans des microstructures et nanostructures à base de silicium, le matériau phare de l'industrie microélectronique.<br />Nous avons étudié un procédé de lithographie assistée par microscope à force atomique (AFM) pour fabriquer des nanofils sub-100-nm ultraminces (8 à 15 nm) de silicium, connectés à une structure de test sur silicium sur isolant (SOI). Les mesures électriques ont mis en évidence le comportement de transistor à effet de champ (FET) des nanocircuits. Le piégeage des électrons aux défauts d'interfaces et de l'oxyde, est la cause de la déplétion cumulative des fils ultraminces au cours des mesures successives I(V). Le dépiégeage peut être contrôlé par application d'une tension sur la grille du nanofil. Les fils ont ainsi révélé un effet mémoire (écriture/lecture par piégeage/dépiégeage sous tension de grille positive/négative).<br />Nous avons par ailleurs étudié le transport du spin dans un canal de silicium. L'étude théorique a souligné la possibilité d'utiliser un faible champ magnétique pour manipuler le spin en obtenant des longueurs de précession et de diffusion de spin micrométriques, compatibles avec la technologie actuelle. L'injection et la collecte électriques ont été réalisées dans un dispositif mémoire magnétique intégrée sur silicium (MEMIS), similaire à un SpinFET. Néanmoins, la qualité des jonctions hybrides métal ferromagnétique/isolant/silicium (FMIS) conditionnent l'efficacité d'injection et de collecte du spin et de l'effet de magnétorésistance ; dans ce sens, nous avons exploré quelques techniques d'élaboration de jonctions Co/AlO/Si et Co/MgO/Si avec des oxydes minces de l'ordre du nanomètre. Nous avons obtenu des jonctions FMIS avec une injection électrique par tunnel direct, ce qui présente une piste prometteuse pour l'injection cohérente du spin. Nous avons également caractérisé des jonctions redresseur semiconducteur ferromagnétique /semiconducteur (MSS) du type Ge3Mn5/Ge qui se sont avérées très intéressantes pour l'injection du spin.
23

SHV β-lactamases : DNA diagnostics and evolution

Hammond, David Scott January 2006 (has links)
TEM and SHV β-lactamases are the most prevalent β-lactamases among Gram-negative bacteria. The introduction and widespread use of expanded-spectrum antibiotics, particularly third generation cephalosporins, has led to the evolution of bacterial strains expressing extended spectrum β-lactamases (ESBLs). ESBLs emerge by genetic point mutation from non-extended spectrum precursors. It was found that multiple β-lactamase families within single isolates complicate the process of detecting the resistance status of isolate using non-quantitative DNA diagnostic methods. Preliminary phenotypic characterisation of probable β-lactamase enzyme family types present in 100 isolates from the Asia-Pacific and South African locales showed that single isolates frequently contained multiple β-lactamase families. SHV, TEM, AMPC and CTX-M β-lactamase families were detected in these isolates using PCR detection methods. Ninety-eight percent of all isolates tested contained as least one β-lactamase gene, with up to four to β-lactamase gene families found to co-exist in single isolates. Kinetic PCR methods for interrogating the polymorphic sites at blaSHV codons 238 & 240 and blaTEM codons 164, 238, 240 as well as promoter polymorphism were developed. A high proportion of blaSHV 238 and 240 mutant alleles was found to correlate with cefotaxime, ceftazidime and aztreonam resistance levels. In an attempt to understand the molecular basis for the co-existence of multiple blaSHV alleles within single isolates, the blaSHV promoter region was cloned from one ESBL expressing isolate. Experimental results showed that blaSHV can exist downstream of two different promoters within a single isolate. Both promoters have previously been reported, and differ by the presence or absence of IS26, which results in a change in the transcription initiation site. The blaSHV gene copy numbers in cis with the different promoters were measured, and it was found that the copy number of the IS26::blaSHV promoter was positively correlated with resistance levels. Cloning and analysis of PCR products showed that different blaSHV variants existed in cis with promoters in individual isolates. However, mutant genes were more abundant downstream of the IS26 promoter. There were no ESBL+ isolates without this promoter. It was concluded that blaSHV in cis with the IS26 promoter is located on an amplifiable replicon, and the presence of the IS26 insertion may facilitate the acquisition of an ESBL+ phenotype. To further confirm the role of IS26 in resistance acquisition, ESBL negative isolates were subjected to serial passage in vitro evolution experiments and fluctuation assays. Results confirm that the insertion of the IS26 element upstream of blaSHV is positively correlated with the ability to exhibit an ESBL phenotype, when such isolates also contain the critical G238S substitution. It was also found that IS26 can catalyse the duplication and mobilisation of blaSHV within an isolate. Fluctuation experiments have shown that the frequency at which such genomic events occur resulting in ESBL phenotypes is extremely low and requires many generations of selection under sub-lethal conditions. A survey of a geographically diverse set of isolates has shown that IS26-blaSHV was found in all of the bacterial populations surveyed. However, it does not appear to be exclusively associated with SHV-mediated ESBL production.
24

Mutation frequency of non-ESBL phenotype SENTRY (Asia-Pacific) isolates of Klebsiella pneumoniae conversion to an ESBL positive phenotype

Dakh, Farshid January 2008 (has links)
Extended spectrum β-lactamases or ESBLs, which are derived from non-ESBL precursors by point mutation of β-lactamase genes (bla), are spreading rapidly all over the world and have caused considerable problems in the treatment of infections caused by bacteria which harbour them. The mechanism of this resistance is not fully understood and a better understanding of these mechanisms might significantly impact on choosing proper diagnostic and treatment strategies. Previous work on SHV β-lactamase gene, blaSHV, has shown that only Klebsiella pneumoniae strains which contain plasmid-borne blaSHV are able to mutate to phenotypically ESBL-positive strains and there was also evidence of an increase in blaSHV copy number. Therefore, it was hypothesised that although specific point mutation is essential for acquisition of ESBL activity, it is not yet enough, and blaSHV copy number amplification is also essential for an ESBL-positive phenotype, with homologous recombination being the likely mechanism of blaSHV copy number expansion. In this study, we investigated the mutation rate of non-ESBL expressing K. pneumoniae isolates to an ESBL-positive status by using the MSS-maximum likelihood method. Our data showed that blaSHV mutation rate of a non-ESBL expressing isolate is lower than the mutation rate of the other single base changes on the chromosome, even with a plasmid-borne blaSHV gene. On the other hand, mutation rate from a low MIC ESBL-positive (≤ 8 µg/mL for cefotaxime) to high MIC ESBL-positive (≥16 µg/mL for cefotaxime) is very high. This is because only gene copy number increase is needed which is probably mediated by homologous recombination that typically takes place at a much higher frequencies than point mutations. Using a subinhibitory concentration of novobiocin, as a homologous recombination inhibitor, revealed that this is the case.
25

Spin-Splitting Calculation for Zinc-blende and Wurtzite Structures of III-V Semiconductors

Kao, Hsiu-Fen 29 June 2012 (has links)
In this study, the spin-splitting energy of the lowest conduction bands in bulk zincblende and wurtzite structures of III-V semiconductors had been investigated by the linear combination of atomic orbital (LCAO) method, the atomic bond-orbital model (ABOM), and the two-band k¡Dp (2KP) model. Spin-splitting calculation for zincblende structures: We develop a 16-band atomic bond-orbital model (ABOM) to compute the spin splitting induced by bulk inversion asymmetry in zincblende materials. This model is derived from the linear combination of atomic orbital (LCAO) scheme such that the characteristics of the real atomic orbitals can be preserved to calculate the spin splitting. The Hamiltonian of 16-band center-zone ABOM (CZABOM) is based on a similarity transformation performed on the nearest-neighbor LCAO Hamiltonian with a second-order Taylor expansion over k at the £F point. The spin-splitting energies in bulk zincblende semiconductors, GaAs and InSb, are calculated, and the results agree with the LCAO and first-principles calculations. However, we find that the spin-orbit coupling between bonding and antibonding p-like states, evaluated by the 16CZABOM, dominates the spin splitting of the lowest conduction bands in the zincblende materials. Spin-splitting calculation for wurtzite structures: The spin-splitting energies in biaxially strained bulk wurtzite material AlN are calculated using the linear combination of atomic orbital (LCAO) method, and the equi-spin-splitting distributions in k-space near the minimum-spin-splitting (MSS) surfaces are illustrated. These data are compared with those derived analytically by two-band k¡Dp (2KP) model. It is found that the results from these two methods are in good agreement for small k. However, the ellipsoidal MSS surface under biaxial compressive strain does not exist in the 2KP model, because the data points are far from the £F point. Instead, three basic shapes of the MSS surface occur in the wurtzite Brillouin zone: a hyperboloid of two sheets, a hexagonal cone, and a hyperboloid of one sheet, evaluated from the LCAO method across the range of biaxial strains from compressive to tensile. The shapes of the equi-spin-splitting (ESS) surfaces near these MSS surfaces have also three types: a hyperboloid of one sheet, an approximate, asymmetric hyperboloid surface, and an opposing hyperboloid of one sheet.
26

ISMS與PIMS整合導入之研究 -以國防部全球資訊網站系統為例 / Research on Importing and Integration of ISMS and PIMS – A Case Study of the World Wide Web for Military of National Defense, Taiwan, R.O.C

孫天貴, Sun, Tien Kuei Unknown Date (has links)
隨著資訊科技的蓬勃發展,資訊技術可以提昇組織效率與競爭力,資訊系統或網站亦是組織營運重要命脈。而在近年來全球資訊安全事件不斷發生,資訊犯罪手法不斷翻新,所肇生的系統損害、資料毀損、個資外洩、財務詐騙事件近來更是層出不窮,對單位或公司而言風險不斷提高,傷害亦相對嚴重,甚至導致公司信譽破產,面臨倒閉威脅,為保護組織內部資訊相關資產與個人資料,並保持組織持續正常運作,資訊安全管理系統(ISMS)與個人資訊管理系統 (PIMS)便是一套可有效控制管理之方法;ISMS與PIMS分兩次來導入,造成組織增加工作負荷,有疊床架屋情形,成本有部分重複投資現象。本研究試著以資料的生命週期,資訊安全的機密性、完整性、可用性,PDCA運作模型...等角度進行本質上探討,來進行整合ISMS與PIMS的整合工作。 經文獻探討與專家學者建議,本研究突破各項盲點,從各角度分析進行多面向整合工作,並提出4點可有效整合具體作法:1. 清查作業流程須包含個人資料所延伸之流程。2. 進行作業流程上資訊資產及個資清查作業。3. 資訊資產及個人資料風險評鑑作業。4. 建立ISMS與PIMS四階文件,產出ISO27001適用性聲明須包含個資法。 本研究以國防部網站系統為例,運用整合結果進行實作,將實作經驗分享給未來有意導入ISMS與PIMS之IT人員,實作結果也證實本研究提出論點確實有效,更有效且更有邏輯性的面對各種資安與個資問題,以作業流程面來分析資安與個資,讓每個控制點更加明確,最後實作運用以各國均能接受的ISO標準(ISO 27001標準包含個資管理流程)來驗證本實作,也證明本研究整合後,在實施(Plan-Do-Check-Act)管理系統確實有效,均能符合相關標準與法規。
27

ST. MARY OF EGYPT IN BL MS COTTON OTHO B. X: NEW TEXTUAL EVIDENCE FOR AN OLD ENGLISH SAINT'S LIFE

Cantara, Linda M. 01 January 2001 (has links)
Scholarship of the anonymous Old English prose Life of St. Mary of Egypt ranges from source studies and linguistic analyses to explorations of Anglo-Saxon female sexuality and comparisons to saints' lives translated by the monk Ælfric, but all of these studies have been based on either the text extant in BL MS Cotton Julius E. vii or on W. W. Skeat's edition of the Julius manuscript, Ælfric's Lives of Saints (1881-1900). There is, however, an as yet unedited fragmentary copy of the Old English Mary of Egypt in BL MS Cotton Otho B. x, a manuscript severely damaged by fire in 1731. Digital imaging of damaged manuscripts in concert with ultraviolet fluorescence and other special lighting techniques has been shown to be effective for restoring the legibility of previously inaccessible texts. By means of such digital facsimiles I have transcribed the text of Mary of Egypt in Otho B. x, have collated this text with Skeat's edition, and have discovered that Otho B. x contains textual evidence not found in Julius E. vii. In this thesis, I present my findings and discuss the significance of this new textual evidence for the Old English Life of St. Mary of Egypt.

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