The vine mealybug, Planococcus ficus (Signoret) (Homoptera: Pseudococcidae) is a pest with significant economic impact on the grape growing industry in South Africa and other parts of the world. With the isolation and synthesizing of the vine mealybug sex pheromone in 2001, new control options for the integrated management of the vine mealybug have been created. The status of sex pheromone monitoring as a tool in the integrated management of the vine mealybug has been evaluated from different perspectives. A significant quantitative difference in male vine mealybug trap catch numbers has been observed between wine and table grape vineyards and results indicated that there were differences in the susceptibility of grape cultivars to vine mealybug. Currently, the delta trap design is the accepted trap design for vine mealybug monitoring. No studies have yet been conducted to determine the optimum trap parameters like size or design. Population pressure may have an influence on the qualitative efficiency of various trap designs. The basis for degree-day forecasting models has been established adequately. However, refinements need to be done and the incorporation of factors such as humidity and regionality also need to be considered. Daily maximum temperatures fluctuating around the upper developmental threshold temperature for prolonged periods of time seemed to suppress population numbers. Different vineyard management practices exist for wine and table grape production. While an action threshold of 65 vine mealybug males per trap per two-week period seems an acceptable threshold for table grape production, it may not be appropriate for wine grape (or raisin grape) production. Using sex pheromone traps for population monitoring is a valid technique in the arsenal of management tactics against the vine mealybug. However, refinements and validation of research results must be done further to build credibility into the monitoring system. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2006.

Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique to non-invasively map the physical and chemical environment within microfluidic devices. In this work FLIM has been used in conjunction with a variety of other techniques to provide a greater insight into flow behaviour and fluid properties at the microscale. The pH-sensitive fluorescent dyes, fluorescein and C-SNARF 1, have been used to generate pH maps of microfluidic devices with a time-gated camera and a time-and-space-correlated single photon counting (TSCSPC) detector, respectively. Using time-gated detection and fluorescein, the fluorescence lifetime images allow for direct reading of the pH. The relative contribution to fluorescence of the acid and basic forms of C-SNARF 1 was spatially resolved on the basis of pre-exponential factors, giving quantitative mapping of the pH in the microfluidic device. Three dimensional maps of solvent composition have been generated using 2-photon excitation FLIM (2PE-FLIM) in order to observe the importance of gravitational effects in microfluidic devices. Two fluidic systems have been studied: glycerol concentration in the microfluidic device was measured using Kiton red; water concentration in a methanolic solution was measured using ANS. The density mismatch between two solutions of different composition induced a rotation of the interface between two streams travelling side by side in a microchannel. The experiment has provided evidence of non-negligible gravitational effects in microflows. 2PE-FLIM has superior capability than methods used previously to assess similar phenomena. FLIM and micro-particle imaging velocimetry (μ-PIV) have been implemented on a custom-built open frame microscope and used simultaneously for multimodal mapping of fluid properties and flow characteristics. It has been shown that viscosity mismatch between two streams induces a non-constant advective transport across the channel and results in a flow profile that deviates from the usual Poiseuille profile, characteristic of pressure driven flow in microfluidic devices.

A promising new approach for studying cold ion-molecule chemical reactions is the combination of laser- or sympathetically-cooled trapped ions and slow-moving molecules from a cold molecule source, such as a quadrupole velocity selector or a Stark decelerator. Previous reaction studies using trapped atomic ions and slow molecules from a quadrupole velocity selector were able to reach average collision energies as low as 1 K. However, the guided molecules had an approximately room temperature rotational energy distribution, so the reactions studied were not truly cold. Thus, a new molecular source for producing translationally and rotationally cold molecules utilizing buffer gas cooling and quadrupole velocity selection was constructed by K. Twyman and characterized for use in cold reaction studies. This new source of cold molecules is referred to as the buffer gas guide. A new ion trap has been designed and built for use with the existing buffer gas guide. The new ion trap apparatus is compact and mechanically compatible with this new guide. It uses a linear Paul ion trap with cylindrical electrodes to trap ions. Two optical axes (one axial and one radial) enable efficient cooling of small ion crystals. A field-free time-of-flight tube and ion detection assembly are also incorporated into the apparatus. A new technique for determining the mass and quantity of trapped ions has also been developed, termed digital ion trap mass spectrometry. The new technique uses a digital RF waveform to trap ions before ejecting the ions radially from the trap using an ejection pulse applied to the trap electrodes. The ions are then detected after free flight along a time-of-flight tube. This technique was characterized by ejecting crystals of various sizes and compositions: Ca^&plus; only, Ca^&plus;/CaF^&plus;, Ca^&plus;/CaOH^&plus;/CaOD^&plus;, and Ca^&plus;/NH^&plus;<sub style='position: relative; left: -.6em;'>3</sub> /NH^&plus;<sub style='position: relative; left: -.6em;'>4</sub> /H₃O^&plus;. A linear relationship between the number of ions ejected (determined by comparing experimental and simulated crystal images) and the integral of the time-of-flight peak was observed for Ca^&plus; and Ca^&plus;/CaF^&plus;. All mass peaks were resolved. Simulations of the trapped ions and their trajectories through the time-of-flight tube were also performed, and excellent agreement between the simulated and experimental mass resolution was observed. Progress towards combining the buffer gas guide with the previously independent ion trap is also presented. It is anticipated that the combined buffer gas guide ion trap apparatus will enable the study of ion-molecule reactions at low temperatures with translationally and rotationally cold molecules. It is anticipated that the new digital ion trap mass spectrometry technique will simplify the study of reactions when multiple product ions whose masses are separated by only 1 AMU are formed. A new ion trap has been designed and built for use with the existing buffer gas guide. The new ion trap apparatus is compact and mechanically compatible with this new guide. It uses a linear Paul ion trap with cylindrical electrodes to trap ions. Two optical axes (one axial and one radial) enable efficient cooling of small ion crystals. A field-free time-of-flight tube and ion detection assembly are also incorporated into the apparatus. A new technique for determining the mass and quantity of trapped ions has also been developed, termed digital ion trap mass spectrometry. The new technique uses a digital RF waveform to trap ions before ejecting the ions radially from the trap using an ejection pulse applied to the trap electrodes. The ions are then detected after free flight along a time-of-flight tube. This technique was characterized by ejecting crystals of various sizes and compositions: Ca+ only, Ca+/CaF+, Ca+/CaOH+/CaOD+, and Ca+/NH+3/NH+4/H3O+. A linear relationship between the number of ions ejected (determined by comparing experimental and simulated crystal images) and the integral of the time-of-flight peak was observed for Ca+ and Ca+/CaF+. All mass peaks were resolved. Simulations of the trapped ions and their trajectories through the time-of-flight tube were also performed, and excellent agreement between the simulated and experimental mass resolution was observed. Progress towards combining the buffer gas guide with the previously independent ion trap is also presented. It is anticipated that the combined buffer gas guide ion trap apparatus will enable the study of ion-molecule reactions at low temperatures with translationally and rotationally cold molecules. It is anticipated that the new digital ion trap mass spectrometry technique will simplify the study of reactions when multiple product ions whose masses are separated by only 1 AMU are formed.

Single atoms are promising candidates for physically implementing quantum bits, the fundamental unit of quantum information. We have built an apparatus for cooling, trapping and imaging single rubidium atoms in microscopic optical tweezers. The traps are formed from a tightly focused off-resonant laser beam, which traps atoms using the optical dipole force. The traps have a diameter of ~1 &mu;m and a depth of ~1 mK. The novelty of our approach is the use a digital mirror device (DMD) to generate multiple independently movable tweezers from a single laser beam. The DMD consists of an array of micro-mirrors that can be switched on and off, thus acting as a binary amplitude modulator. We use the DMD to imprint a computer-generated hologram on the laser beam, which is converted in to the desired arrangement of traps in the focal plane of a lens. We have developed fast algorithms for calculating binary holograms suitable for the DMD. In addition, we use this method to measure and correct for errors in the phase of the wavefront caused by optical aberrations, which is necessary for producing diffraction-limited focal spots. Using this apparatus, we have trapped arrays of up to 20 atoms with arbitrary geometrical arrangements. We exploit light-assisted collisions between atoms to ensure there is at most one atom per trapping site. We measure the temperature of the atoms in the traps to be 12 &mu;K, and their lifetime to be 1.4 s. Finally, we demonstrate the ability to select individual atoms from an array and transport them over a distance of 14μm with laser cooling, and 5 &mu;m without.

<p>Atomic ions trapped in microfabricated surface traps can be utilized as a physical platform with which to build a quantum computer. They possess many of the desirable characteristics of such a device, including high fidelity state preparation and readout, universal logic gates, and long coherence times, and can be readily entangled with each other through photonic interconnects. The use of optical cavities integrated with trapped ion qubits as a photonic interface presents the possibility for order of magnitude improvements in performance in several key areas for their use in quantum computation. The first part of this thesis describes the design and fabrication of a novel surface trap for integration with an optical cavity. The trap is custom made on a highly reflective mirror surface and includes the capability of moving the ion trap location along all three trap axes with nanometer scale precision. The second part of this thesis demonstrates the suitability of small microcavities formed from laser ablated, fused silica substrates with radii of curvature in the 300-500 micron range for use with the mirror trap as part of an integrated ion trap cavity system. Quantum computing applications for such a system include dramatic improvements in the photon entanglement rate of up to 10 kHz, the qubit measurement time down to 1 microsecond, and the qubit measurement error rate down to the 1e-5 range. The final part of this thesis describes a performance simulator for exploring the physical resource requirements and performance demands to scale a quantum computer to sizes capable of implementing quantum algorithms beyond the limits of classical computation.</p> / Dissertation

Current methods of mosquito surveillance estimate general population abundances, but fail to represent the relationship of vector abundance to host density important to determining transmission risk of mosquito-borne pathogens (MBP). We sought to address this limitation by creating a novel mosquito trap that directly sampled mosquitoes seeking to feed on nesting birds. The primary objectives of this study were to (1) assess the efficiency of the Nest Mosquito Trap (NMT) and how this is affected by nest box size. (2) assess whether the NMT affects bird, specifically nest success in Prothonotary Warblers (Protonotaria citrea), and adult behavior. (3) compare our novel trap to existing methods. (4) profile the ecological parameters associated with bird/ mosquito interactions. Our results allow us to conclude that the NMT is not only an effective means of capturing host-seeking mosquitoes and measuring mosquito/ bird interactions, but does not have a deleterious effect on avian nesting success.

Les facteurs de croissance endothéliaux (VEGFs) sont produits par les tumeurs qui sont hypoxiques. Principaux responsables de la néo-vascularisation pathologique, ils régulent le stroma tumoral. Les nouvelles stratégies qui ciblent et inhibent le VEGF ouvrent vers la thérapie anti-cancéreuse moderne. Elles ont pour but de contrôler l’angiogenèse tumorale plutôt que la détruire. Le défi est donc de piéger sélectivement le VEGF produit en excès, dans le microenvironnement tumoral, sous l’effet de l’hypoxie. La thèse présentée dans ce manuscrit est consacrée à la réalisation d’une nouvelle stratégie ciblante par l’intermédiaire de cellules, aussi appelée « Cheval de Troie ». Elle combine dans la même entité, une unité de ciblage et un système de délivrance spécifique d’un gène/molécule thérapeutique. Dans le but d’adresser la thérapie aux cellules cancéreuses sans affecter les cellules saines, un modèle de cellules endothéliales de type précurseur (CEPs) a été utilisé comme cellules ciblantes capables d’atteindre spécifiquement le site tumoral. Les CEPs ont été « armées » pour exprimer un gène thérapeutique chargé d’inhiber le VEGF. La neutralisation a été obtenue par la production d’une forme soluble du récepteur-2 du VEGF (VEGFR2 soluble), agissant comme inhibiteur. Caractéristique des tumeurs solides se développant, l’hypoxie a été choisie pour déclencher/éteindre l’expression et la sécrétion du VEGFR2 soluble, en introduisant, en amont du gène thérapeutique, une séquence régulatrice : HRE. Adressé au site tumoral par les CEPs, le régulateur de l’angiogenèse qu’est la forme soluble du VEGFR2, est exprimé de manière conditionnée et réversible, à l’hypoxie. Ceci ouvre à de nouvelles stratégies de normalisation contrôlée et stable des vaisseaux tumoraux en vue de l’utilisation de thérapies combinées. / Vascular endothelial growth factors (VEGFs) are over-expressed upon hypoxia in solid tumors. Major actors directing pathologic neo-vascularisation, they regulate the stromal reaction. Novel strategies that target and inhibit VEGF bring promise to modern anti-cancer therapies. They aim to control rather than destroy tumor angiogenesis. Consequently, the challenge is to selectively trap VEGFs, over-produced upon hypoxia, in the tumor microenvironment. The thesis presented in this manuscript focuses on the design of a novel cell-based targeting strategy, so-called “Trojan Horse”, combining in the same engineered entity, a targeting unit and a specific drug/gene delivery system. Aiming to address the therapy to cancer cells without affecting healthy cells, a model of endothelial precursor cell (EPCs) was used as targeting cell able to reach specifically the tumor site. EPCs were “armed” to express a therapeutic gene to inhibit VEGF. Trapping was attempted based on the production of a soluble form of the VEGF receptor-2 (sVEGFR2) as a candidate inhibitor. Hypoxia, a hallmark of developing solid tumors, was chosen to turn on/off the sVEGFR2 expression and secretion by introducing, upstream of the therapeutic gene, a hypoxia response element (HRE) regulating sequence. Properly addressed by the EPCs to the tumor site, such angiogenesis regulator as the soluble form of VEGFR2 is, was chosen to be expressed in a hypoxia-conditioned and reversible manner. This opens new strategies for a stably controlled normalization of tumor vessels in view of adjuvant design for combined therapies.

The East Shetland Basin is a superb natural laboratory in which to study the role that normal fault growth and linkage has in determining petroleum prospectivity. Use of several high density 3D seismic volumes and over 250 boreholes permits key aspects of the Late Jurassic rift and its Permo-Triassic precursor to be analysed and its role on hydrocarbon trap formation, reservoir distribution and migration determined. The regional interpretation has revealed the generation of a North Sea archipelago of Upper Jurassic islands, the role of relay ramps in controlling syn-rift sediment dispersal patterns and the impact of normal faults of the later episode crossing and offsetting those generated by the earlier phase. The uplift, erosion and meteoric flushing of Upper Jurassic and older strata within the exposed fault blocks could potentially have huge consequences for the Brent play by enhancing reservoir properties and hence, help identify new play opportunities down-dip of major structures. Fault control on sediment dispersal can also be documented in a more localized study on the Cladhan Field, the site of a pronounced basin-margin relay ramp. This recent discovered set of syn-rift density flows illustrates how the development and distribution of depositional gradients and transport pathways form subtle play types. The Cladhan area is just one of several locations throughout the East Shetland Basin where the interaction of multiple rift phases is influential in the structural feedback after the Upper Jurassic rifting event. The delicate interaction and reactivation of underlying structural trends creates a series of multi-tiered fault block systems which can define several aspects of a petroleum system, depending upon the strike, polarity and level of reactivation of faults from one rift to another. The observations of fault growth and linkage in the Northern North Sea may provide generic lessons that help in determining petroleum prospectivity in other hydrocarbon rift basins (e.g. E. Africa and the N. Atlantic seaboard of North America).

Approved for public release, distribution is unlimited / The attack of choice for a professional attacker is system subversion: the insertion of a trap door that allows the attacker to bypass an operating system's protection controls. This attack provides significant capabilities and a low risk of detection. One potential design is a trap door that itself accepts new programming instructions. This allows an attacker to decide the capabilities of the artifice at the time of attack rather than prior to its insertion. Early tiger teams recognized the possibility of this design and compared it to the two-card bootstrap loader used in mainframes, since both exhibit the characteristics of compactness and adaptability. This thesis demonstrates that it is relatively easy to create a bootstrapped trap door. The demonstrated artifice consists of 6 lines of C code that, when inserted into the Windows XP operating system, accept additional arbitrary code from the attacker, allowing subversion in any manner the attacker chooses. The threat from subversion is both extremely potent and eminently feasible. Popular risk mitigation strategies that rely on defense-in-depth are ineffective against subversion. This thesis focuses on how the use of the principles of layering, modularity, and information hiding can contribute to high-assurance development methodologies by increasing system comprehensibility. / Civilian, Naval Postgraduate School

This study examines the phenomenon of the usage of e-commerce in relation to firms’ internationalization process. Consequently, the study investigates risks and psychic distance in relation to prior research within International business, Internationalization and e- commerce, while focusing on the latest era of academia, namely “Internetalization”. The study investigates how e-commerce and its tools reduce perceived risks associated with firms’ internationalization process and what challenges Swedish SME’s identify while using e- commerce as a tool for internationalization. The study takes a qualitative, multiple case study approach focusing on Swedish SME’s operating in foreign markets within the retail industry. The findings indicate that e-commerce has the potential to generate international market expansion for Swedish SME’s. Further findings show that e-commerce and its tools are leveraged by Swedish SME’s to source, access and exchange valuable information whilst reducing perceived risk related to internationalization since it gives SME’s access to essential information needed for further expansion. Two main challenges are identified. Firstly, trustworthiness and secondly transforming gathered information into valuable information and knowledge. Consequently, the main challenge identified in the internationalization process of Swedish SME’s, resides in coping with the underlying presence of “psychic distance” or “virtuality trap”.