• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1472
  • 517
  • 492
  • 327
  • 219
  • 181
  • 144
  • 31
  • 30
  • 24
  • 23
  • 23
  • 18
  • 18
  • 17
  • Tagged with
  • 4191
  • 415
  • 395
  • 378
  • 367
  • 359
  • 354
  • 329
  • 315
  • 308
  • 304
  • 299
  • 293
  • 288
  • 287
  • 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.
1001

Select CD : computer support system for making tree species and reproduction cutting decisions in the coastal forest of BC

Klinka, Karel, Varga, Pal, Chourmouzis, Christine January 1999 (has links)
"SELECT CD is a site-specific, decision-support tool for selecting ecologically viable tree species, reproduction cuttings, and regeneration methods in the coastal forest (CDF, CWH, and MH zones). SELECT CD integrates information from several existing guides with new information from literature and recent research into a single, user-friendly resource. SELECT CD also includes a rich library of visuals and an illustrated glossary of technical terms."
1002

Relationships between coastal Douglas-fir site index and synoptic categorical measures of site quality

Klinka, Karel, Carter, R. E. (Reid E.), Chourmouzis, Christine January 2001 (has links)
Knowledge of ecological characteristics of trees, sites and tree growth on different sites is fundamental for silvicultural decision-making and planning. With the biogeoclimatic ecosystem classification in place, silvicultural management in British Columbia has been given an ecological foundation; however, relationships between growth and site have not yet been fully investigated. The purpose of this study was to determine how height growth of Douglas-fir within the drier portion of the CWH zone varies with site. We adopted site index (m @ 50 yr bh) as a species-specific measure of forest productivity, recognizing that it indicates height growth performance at a selected point in time. If forest productivity is correlated with ecological measures of site quality, what site factors should be used to quantify the relationships? Because of compensating effects, the numerous site factors can be reduced to four primary (synoptic) factors that directly affect plant establishment and growth: climate (light and temperature), soil moisture, soil nutrients, and soil aeration (not used in this study).
1003

New height growth models for western larch in British Columbia

Klinka, Karel, Brisco, David James, Nigh, Gordon D. (Gordon Donald), Chourmouzis, Christine January 2001 (has links)
Western larch (Larix occidentalis Nutt.) is a locally important species in the Nelson Forest Region, and to a lesser extent, in the Kamloops Forest Region. Its range extends from west of the Rockies to Okanagan Lake, and north to Salmon Arm, in the IDF, ICH, MS, and ESSF biogeoclimatic zones. Prior to this study, the site index curves developed for western larch in western Montana were used to model height and estimate site index in British Columbia. It has been suggested that these curves may not adequately reflect the height growth patterns of western larch in BC. Differences could arise from genetics, different methods of selecting sample trees, or climatic differences. The objective of this project was to produce accurate height growth models for western larch in BC.
1004

Trembling aspen site index in relation to site quality in northern British Columbia

Klinka, Karel, Chen, Han Y. H., Chourmouzis, Christine January 1998 (has links)
Accurate and reliable predictions of site index (height of dominant trees at a reference age, usually 50 years at breast-height) for timber crop species is essential for silvicultural site-specific decision making. Site index can be predicted from site quality once the relationship between site index and site quality has been quantified. Site quality is defined as the sum of all environmental factors affecting the biotic community, such as the factors directly influencing the growth of vascular plants (light, heat, soil moisture, soil nutrients, and soil aeration). Since these factors vary greatly in time, indirect estimates of site quality have widely been used as predictors for site index in various multiple regression models. Trembling aspen (Populus tremuloides Michx.) is the most widely distributed broadleaf species in British Columbia, especially in the Boreal White and Black Spruce (BWBS) biogeoclimatic zone. Growing this species for sustainable timber production requires a good understanding of its productivity attributes and accurate predictions of its growth. This extension note presents (1) relationships between trembling aspen site index and some indirect measures of site quality, and (2) site index prediction models using the indirect measures of site quality as predictors.
1005

Besant beginnings at the Fincastle site : a late middle prehistoric comparative study on the northern plains

Foreman, Christine, University of Lethbridge. Faculty of Arts and Science January 2010 (has links)
The Fincastle Bison Kill Site (DlOx-5), located approximately 100 km east of Lethbridge, Alberta, has been radiocarbon dated to 2 500 BP. Excavations at the site yielded an extensive assemblage of lithics and faunal remains, and several unique features. The elongated point forms, along with the bone upright features, appeared similar to those found at Sonota sites within the Dakota region that dated between 1 950 BP and 1 350 BP. The relatively early date of the Fincastle Site prompted a re-investigation into the origins of the Besant Culture. The features, faunal and lithic assemblages from twenty-three Late Middle Prehistoric sites in Southern Alberta, Saskatchewan, Montana, Wyoming, and the Dakotas were analyzed and compared. The findings show that Fincastle represents an early component of the Besant Culture referred to as the Outlook Complex. This analysis also suggests a possible Middle Missouri origin of the Fincastle hunters, as well as the entire Besant Culture. / xii, 183 leaves : ill. (chiefly col.) ; 29 cm
1006

MITIGATION OF WEB-BASED PROGRAM SECURITY VULNERABILITY EXPLOITATIONS

Shahriar, HOSSAIN 30 November 2011 (has links)
Over the last few years, web-based attacks have caused significant harm to users. Many of these attacks occur through the exploitations of common security vulnerabilities in web-based programs. Given that, mitigation of these attacks is extremely crucial to reduce some of the harmful consequences. Web-based applications contain vulnerabilities that can be exploited by attackers at a client-side (browser) without the victim’s (browser user’s) knowledge. This thesis is intended to mitigate some exploitations due to the presence of security vulnerabilities in web applications while performing seemingly benign functionalities at the client-side. For example, visiting a webpage might result in JavaScript code execution (cross-site scripting), downloading a file might lead to the execution of JavaScript code (content sniffing), clicking on a hyperlink might result in sending unwanted legitimate requests to a trusted website (cross-site request forgery), and filling out a seemingly legitimate form may eventually lead to stealing of credential information (phishing). Existing web-based attack detection approaches suffer from several limitations such as (i) modification of both server and client-side environments, (ii) exchange of sensitive information between the server and client, and (iii) lack of detection of some attack types. This thesis addresses these limitations by mitigating four security vulnerabilities in web applications: cross-site scripting, content sniffing, cross-site request forgery, and phishing. We mitigate the exploitations of these vulnerabilities by developing automatic attack detection approaches at both server and client-sides. We develop server-side attack detection frameworks to detect attack symptoms within response pages before sending them to the client. The approaches are designed based on the assumption that the server-side program source is available for analysis, but we are not allowed to alter the program code and the runtime environments. Moreover, we develop client-side attack detection frameworks so that some level of protection is present when the source code of server websites (either trusted or untrusted) is not available. Our proposed solutions explore several techniques such as response page parsing and file content analysis, browser-level checking of requests and responses, and finite state machine-based behavior monitoring. The thesis evaluates the proposed attack detection approaches with real-world vulnerable programs. The evaluation results indicate that our approaches are effective and perform better than the related work. We also contribute to the development of benchmark suites for evaluating attack detection techniques. / Thesis (Ph.D, Computing) -- Queen's University, 2011-11-29 09:44:24.465
1007

The role of Caulobacter crescentus XerC and XerD recombinases in site-specific recombination

Liu, Hua 12 1900 (has links)
XerC et XerD, deux recombinases impliquées dans la recombinaison site spécifique, résolvent les multimères d’ADN en monomères. Cette réaction se produit au niveau du site dif du chromosome, et nécessite le domaine C-terminale de la protéine de division cellulaire FtsK. Caulobacter crescentus est une bactérie aquatique de type Gram-négative qui se retrouve dans plusieurs environnements. Elle présente un cycle cellulaire asymétrique avec deux types de cellules distinctes. Cette propriété peut être utilisée pour synchroniser la croissance d’une population bactérienne pour permettre l’étude de l’expression de gènes à travers le temps et les liens entre le cycle cellulaire et le développement de la bactérie. La liaison à l’ADN et la capacité de former des complexes covalents (phosphotyrosyl) avec le site dif de C. crescentus (ccdif) ont été testé pour les recombinases de C. crescentus (ccXerC et ccXerD). Les deux recombinases ont eu une meilleure liaison au demi-site gauche de ccdif et sont incapable d’effectuer une liaison coopérative, contrairement à ce qui se produit au niveau du site dif de E. coli. La formation de complexes covalents a été testé en utilisant des «substrats suicides avec bris» marqués à la fluorescence ainsi que des protéines de fusion (marquées ou non à la fluorescence). Des complexes ADN-protéines résistants à la chaleur et au SDS ont été observé lors de la réaction de ccXerC et ccXerD de type sauvage avec ccdif, mais pas lors de la réaction de mutants avec le même ADN. Des complexes covalents phosphotyrosine sont formés de façon plus efficace sur les substrats suicides avec un bris au niveau du brin supérieur que ceux ayant un bris au niveau du brin inférieur. Dans les deux cas, c’est ccXerC qui est resté lié de façon covalente à l’ADN de ccdif. / In most bacteria, the chromosomal dimer resolution process is mediated by two tyrosine recombinases, XerC and XerD, which bind cooperatively and perform the recombination reaction at the dif site near the terminus of replication. This reaction also requires the C-terminal domain of the cell division protein FtsK. Caulobacter crescentus is an aquatic Gram-negative bacterium found in various environments. This bacterium has an asymmetric cell cycle which can be used to synchronize cell growth in order to study the temporal expression of a gene and the interconnection between the cell cycle and development. The binding activity and the formation of phosphotyrosyl complex of the C. crescentus recombinases, ccXerC and ccXerD, were tested on the C. crescentus dif (ccdif) site. Both ccXerC and ccXerD bound preferentially to the left half-site of ccdif and showed reduced cooperative binding, unlike what was found with the E. coli dif site. Covalent complex formation activity was tested by using fluorescently labelled linear “nicked suicide substrates” and labelled proteins. Heat and SDS-resistant protein-DNA complexes were formed when both wild-type ccXerC and ccXerD reacted with ccdif but not in the presence of active-site tyrosine mutant proteins. Phosphotyrosine complexes formed on the top-nicked suicide substrate were found to be more efficient than on the bottom-nicked suicide substrates and surprisingly ccXerC remained bound to both top and bottom-nicked ccdif suicide substrates.
1008

Système de listes de vérification interactives du niveau de conformité des maquettes avec les recommandations des fabricants de plateformes mobiles

Ghezzal, Nadir 08 1900 (has links)
La demande d'applications pour les plateformes mobiles a explosé ces dernières années. Chaque compagnie souhaite maintenant offrir pour ces nouveaux appareils les mêmes services que ceux offerts traditionnellement sur internet. Cependant, ces entreprises n'ont bien souvent que peu ou pas de connaissances concernant le développement et le déploiement de tels services. Généralement, la solution choisie consiste à externaliser ce travail en le sous-traitant à une autre compagnie. Dans ce contexte, il est souvent compliqué de s'assurer d'une part que le sous-traitant respecte le cahier des charges et d'autre part que le travail fourni est conforme aux recommandations émises par les fabricants des plateformes mobiles. Afin de pallier au second problème, nous avons créé un système de listes de vérification interactives pour plateformes mobiles. Ce système permet d'évaluer le niveau de conformité des différents composants de l'interface d'une application développée pour une plateforme mobile avec les recommandations du fabricant de cette plateforme. La solution retenue permet de se concentrer sur certains éléments particuliers de l'interface et pallie ainsi aux limites des listes de vérification classiques qui sont souvent trop longues et peu pratiques. La solution retenue offre de plus la possibilité de comparer facilement les caractéristiques des plateformes mobiles entre elles. Pour réaliser ce système, nous avons consulté de nombreux documents portant sur l'univers des plateformes mobiles afin de mieux appréhender leurs spécificités. Suite à l'étude de différentes plateformes, deux d’entre elles, soit iOS et BlackBerry, ont été retenues (il faut noter que la compagnie où s'est effectuée la recherche disposait déjà d'applications pour ces plateformes). Nous avons ensuite analysé plus finement la documentation technique fournie par chacun des fabricants afin d'en extraire les points importants. Afin que les données soient comparables, nous avons créé une nomenclature commune regroupant les composants de l'interface graphique en grandes familles (ex. : barres, saisie d'information, …) en tenant compte également du type d'interaction avec l'appareil (ex. : écran tactile). Nous avons ensuite conçu une solution permettant d'évaluer le niveau de conformité d'une application. L'idée retenue se base sur des listes de vérification permettant de systématiser le processus d'évaluation. Pour pallier aux limites de ces listes, souvent trop longues, nous permettons à l'utilisateur, via un ensemble de filtres, de se concentrer sur un sous-ensemble de composants de l’interface qu'il souhaite évaluer. L'implémentation de cette solution a été réalisée en totalité grâce à des technologies libres et de standard ouvert. De cette façon, nous nous sommes assurés de la portabilité de la solution développée et de l’absence de coûts supplémentaires liés à l'achat de licences. Le système utilise les standards web et repose sur une architecture basée sur le système d'exploitation GNU/Linux, le serveur web Apache, la base de données MySQL et le langage de scripts PHP. Ces logiciels ont déjà fait leurs preuves aussi bien pour les entreprises que pour les particuliers. De plus, la communauté très active qui s'est constituée autour de ces logiciels assure un bon support et une grande stabilité. Après avoir fait le choix de l’environnement de développement, la phase d'implémentation s'est ensuite déroulée en plusieurs étapes. Tout d'abord, l'information a été structurée selon la nomenclature mentionnée plus haut afin de créer le schéma de la base de données. Ensuite, toutes les pages ont été codées avec le langage à balises HTML et les scripts PHP pour le côté serveur et avec JavaScript pour le côté client. Enfin, l'information peut être affichée grâce aux feuilles de style en cascade (CSS), une technologie web permettant de séparer le fond de la forme en matière de mise en page. Nous avons choisi un modèle de développement itératif qui a impliqué les principaux utilisateurs dès les premières étapes de la conception du système. Cette implication s’est poursuivie jusqu’à la fin du projet afin de s'assurer que les fonctionnalités mises en place répondaient aux attentes. L’architecture modulaire qui a été retenue permet également d’adapter facilement le système aux besoins futurs. Afin de mieux comprendre comment on utilise le système, on passe en revue les différentes étapes nécessaires à la réalisation d'une évaluation. Enfin, on a réalisé une étude avec quatre utilisateurs pour évaluer l'utilisabilité du système et recueillir leur niveau de satisfaction. / The need for mobile platforms has increased in the last decade. Companies offering traditional internet services now want to move their applications on these new devices. But, most of the time, these companies do not really have the knowledge to create such applications and often ask a third party company to do the job for them. In this context, it is difficult to evaluate if the solution developed follows the recommendations of the device maker. A system based on interactive check lists has thus been created for this purpose. This system enables the evaluation of the conformity level of an application with the recommendations of the device maker, thanks to numerous filters that let the user focus on specific parts of the graphic interface. The idea behind the project was first to address some problematic issues with classical check lists and to enable the comparison of several mobile platforms with regard to specific interface components. To create this system, a lot of information about mobile platforms has first been collected. After reviewing many mobile platforms, it was decided to focus on iOS and BlackBerry, since the company where the research was performed had already applications running on them. For each platform, the major recommandations to be satisfied were identified. Also, to be sure that the extracted recommendations could be compared, a common nomenclature has been created, where the recommandations are grouped by interface components (ex: bars, data input,…) and by the type of interaction (ex: touch screen). After these preliminary steps, a solution for evaluating the level of compliance was created. We favored a check list approach because it offers a systematic evaluation process. To avoid lists of excessive length, filters were introduced in the system to allow the user to focus on particular aspects of the interface. The implementation was totally realized with open source technologies and open standards. This choice was motivated by the portability of the developed system and by the absence of licence fees. The system relies on web standards and runs on an architecture made of the CNU/Linux operating system, Apache web server, MySQL database and the script language PHP. This software has already proven its reliability for enterprises and for home users. Furthermore, the community evolving around this software offers a good support and ensures a high level of stability. After setting up the development environment, the implementation phase was engaged and took place over a number of phases. The first phase was the creation of the database structure, using the aforementioned nomenclature. The next phase was dedicated to the coding of the different web pages, thanks to the tag language HTML and the PHP scripts on the server side and JavaScript on the client side. Finally, the web page setting was developed using the cascading style sheet (CSS), a web technology that segregates the substance from the style of the web content. We chose an iterative development model where the end users were involved from the early stages of the project. This approach provides a guarantee that the user requirements are fulfilled and that any new developments will be in accordance with the expectations. Furthermore, the system is such that it can be easily modified to tackle future needs. To be able to understand how we use the systeme, we are reviewing the different steps needed to realise an evaluation. Finally, we have made a study with four users to evaluate the usability of the system and to gather their satisfaction level. / L'ensemble de mon travail a été réalisé grâce a l'utilisation de logiciel libre.
1009

Digital Tuft Flow Visualisation of Wind Turbine Blade Stall

Swytink-Binnema, Nigel 20 May 2015 (has links)
Wind turbines installed in the open atmosphere experience much more complex and highly-varying flow than their counterparts in wind tunnels or numerical simulations. In particular, aerodynamic stall—which occurs often on stall-regulated wind turbines in such variable flow conditions—can affect both wind turbine blade lifespan and noise generation. A field test site was therefore installed at the outer limits of the city of Waterloo, Ontario to study a small-scale 30 kW stall-regulated wind turbine. Experimental equipment was installed to monitor parameters such as wind speed and direction, electrical power output, blade pitch angle, rotor rotational speed, and wind turbine yaw orientation. Extensive hardware and software was developed and installed to wirelessly collect data from all instrumentation. Tufts and a remote-operated camera were also installed on one of the two blades of the 10 m diameter horizontal-axis turbine. In a variation on the tuft flow visualisation technique, video files were analysed using a novel digital image processing code. The code was developed in MATLAB to calculate the fraction of the blade which was stalled by determining the position and angle of each tuft in every video frame. The algorithm was able to locate on average 85% of the visible tufts and correctly tagged those which were stalled with a bias of only −5% compared to the typical manual method. When the algorithm was applied to 7 h of tuft video at the outboard 40% of the blade, the total average fraction of stalled tufts varied from 5% at 5 m/s to 40% at 21 m/s. This trend was expected for the stall-regulated design since, as the wind speed is increased, the stall progresses from inboard to outboard regions and from trailing edge to leading edge. The 7 h time period represents at least a two order-of-magnitude increase compared with time periods analysed using previous manual methods. This work has demonstrated a digital implementation of tuft flow visualisation which lends statistical validity (through long-time-period averaging) to a common tool for researching wind turbine stall. The speed and ease with which the tuft method can be implemented, combined with the high cost per energy of small-scale wind turbines, suggest that this digital algorithm is a highly beneficial tool for future studies.
1010

Caratterizzazione dei meccanismi di resistenza agli insetticidi nelle popolazioni italiane dell'afide verde del pesco Myzus persicae (Sulzer) / CHARACTERISATION OF INSECTICIDE RESISTANCE MECHANISMS IN ITALIAN POPULATIONS OF THE GREEN PEACH APHID MYZUS PERSICAE (SULZER)

PANINI, MICHELA 28 January 2015 (has links)
L’afide del pesco Myzus persicae rappresenta uno degli insetti più dannosi in agricoltura. Estremamente polifago e cosmopolita, viene combattuto principalmente con trattamenti insetticidi. Nel corso degli ultimi anni neonicotinoidi e piretroidi hanno rappresentato i componenti principali delle strategie di difesa contro questa specie, ma recenti programmi di monitoraggio condotti in Sud Europa hanno rivelato la presenza di popolazioni resistenti, mettendo in dubbio l’efficacia a lungo termine di queste classi di prodotti. Il presente lavoro prende in esame la diffusione dei principali meccanismi di resistenza agli insetticidi nelle popolazioni di M. persicae presenti sul territorio italiano. La prima parte si concentra sulle resistenze target-site e considera la distribuzione delle principali mutazioni che sono state associate alla resistenza a neonicotinoidi e piretroidi. La seconda parte riguarda le resistenze metaboliche e analizza le principali classi di enzimi associate ad attività di sequestro o detossificazione delle molecole di insetticida. Infine, il progetto si focalizza sulla caratterizzazione delle possibili interazioni tra tali enzimi detossificanti e molecole sinergizzanti quali il ben noto piperonil butossido (PBO). I risultati ottenuti consentiranno di migliorare le strategie di difesa per evitare trattamenti inefficaci e mantenere il più a lungo possibile l’efficacia dei prodotti oggi disponibili per il controllo di M. persicae. / The green peach aphid Myzus persicae is a globally significant crop pest, controlled mainly by chemical treatments. In recent years neonicotinoids and pyrethroids have been the main components of pest management strategies used by growers. However, recent monitoring programmes in Southern Europe have shown the widespread presence of resistant populations, posing a serious threat to the long-term efficacy of these insecticide classes. The present work aims to characterise the main biochemical and molecular mechanisms responsible for insecticide resistance in Italian populations of M. Persicae. The first part is focused on target-site resistance and consider the frequency and distribution of the main target-site mutations associated with neonicotinoid and pyrethroid resistance. The second part is related to metabolic resistance and analyses the involvement of detoxifying enzymes able to sequester or metabolise the insecticide molecules. Furthermore, the project aims to characterise possible interactions between those enzymes and synergistic compounds like the well-known piperonyl butoxide (PBO). Results obtained by this investigation will help to improve insecticide resistance management strategies, in order to avoid ineffective applications and maintain the long-term sustainability of chemical control against M. persicae.

Page generated in 0.0525 seconds