In 1994, military historian Martin Van Creveld presented his hypothesis about the future of modern military conflicts. He argued that these conflicts primarily would involve non-state actors or state actors employing unconventional means and methods. Thirty years later, his hypothesis appears more relevant than ever. He claims that his theory of maneuver warfare should be able to explain success against this type of adversary.  This thesis aims to test whether Van Creveld's theory of maneuver warfare can lead to success when a conventional actor faces an unconventional opponent. The purpose of this thesis is to contribute to the current research regarding maneuver warfare and increase understanding of whether his theory can be applied against an unconventional adversary.  The theory has been applied on the U.S. lead coalition during Operation Anaconda and Operation Phantom Fury, from early 2000s. The result of the thesis implies that Van Creveld's theory of maneuver warfare can explain the outcome of both operations and should therefore be considered as valid. However, several circumstances are identified that should be considered in modern military conflicts in the future.

This research presents a Resource-constrained Critical Path Method (RCPM) technique that capitalizes on and improves the existing Critical Path Method (CPM) and Resource-Constrained Scheduling (RCS) techniques. A traditional CPM schedule is not realistic since it assumes unlimited resources, some of which are highly limited in practice. Although traditional RCS techniques can consider resource limitations, they do not provide correct floats and the critical path as the CPM does. The difference between the theoretical remaining total float and the real remaining total float is referred to as "Phantom Float" in this study. Another disadvantage of the traditional RCS techniques is that work sequence in the schedule could be considerably changed with a schedule update resulting in high costs to reorganize it. These problems are caused by the fact that, in addition to technological relationships, a resource-constrained schedule contains resource dependencies between activities that are neglected in traditional RCS techniques. This study proposes a step-by-step RCPM algorithm to consider those resource-constrained relationships. Hence, the method can identify real floats and correct critical paths, considering both technological and resource-dependent relationships. RCPM also provides a certain level of stability with a schedule update due to the newly identified resource relationships. Based on the RCPM algorithm, a prototype RCPM system has been developed using Visual C++, Visual Basic, and Ra (Primavera Project Planner API). The system is integrated with P3, so that it reads project information directly from a P3 project, performs necessary RCPM procedures, and updates the P3 project to contain identified resource relationships. To make the system more practical, functions to handle multiple project calendars and progressed schedules have been included as well. / Ph. D.

Since its inception, Magnetic Resonance Imaging (MRI) has largely been used for qualitative diagnosis. Radiologists and physicians are increasingly becoming interested in quantitative assessments. The American College of Radiology (ACR) developed an accreditation program that incorporates tests pertaining to quantitative and qualitative analyses. As a result, sites often use the ACR procedure for daily quality assurance (QA) testing. The ACR accreditation program uses information obtained from clinical and phantom images to assess overall image quality of a scanner. For the phantom assessment, a human observer performs manual tests on T1 and T2-weighted volumes of the provided phantom. As these tests are tedious and time consuming, the primary goal of this research was to fully automate the procedure for QA purposes. The performance of the automated procedure was assessed by comparing the test results with the decisions made by human observers. The test results of the automated ACR QA procedure were well correlated with that of human observers. The automated ACR QA procedure takes approximately 5 minutes to complete. Upon program completion, the test results are logged in multiple text files. To this date, no QA procedure has been reported for Diffusion Tensor Imaging (DTI). Therefore, the secondary goal of this thesis was to develop a DTI QA procedure that assess two of the associated features used most in diagnosis, namely, diffusion anisotropy and the direction of primary diffusion. To this end, a physical phantom was constructed to model restricted diffusion, relative to axon size, using water-filled polytetrafluoroethylene (PTFE) microbore capillary tubes. Automated procedures were developed to test fractional anisotropy (FA) map contrast and capillary bundle (axon) orientation accuracy. / Master of Science

On a regular basis, project managers concentrate their efforts on critical and near-critical activities. However, the concepts of total float and critical path lose their significance after applying resource-constrained scheduling (RCS) methodologies. RCS techniques solve the resource conflicts but create phantom float in the schedules (i.e., a float that does not exist). RCS techniques overlook the resources relationships between activities that compete for the same but unavailable resources. Therefore, each time an activity uses this apparent float (phantom float), there is a resource violation in the schedule. Due to the projects' size and complexity, schedulers use scheduling software such as Primavera P6 to fix the resource conflicts of a schedule. The software correctly determines the activities' earliest dates that satisfy the resource limitations, but they calculate total float based on a "Time Context" ignoring the presence of resource constraints. Thus, the results show incorrect total float values and a broken critical path. The lack of a continuous critical path makes impossible the anticipation of the impact of a delaying event in the project completion time. Several algorithms have been developed to address the shortcomings of RCS methods. These RCS related algorithms were developed with the aim of providing project managers a tool to correctly schedule and identify critical activities with respect to time and resource allocation and correctly calculate the total float of each activity under resource constraints. In this regard, the Resource-Constrained Critical Path Method (RCPM) is an algorithm that correctly calculates the floats of activities and identifies a continuous critical path in resource-constrained schedules. Regardless of the RCPM provides more reliable float values than traditional RCS-related algorithms, there are some shortcomings that must be addressed to enhance its capability. This study addresses the existing shortcomings of RCPM to make it more practical for real construction projects. / Doctor of Philosophy / One of the challenges of resource allocation is resource availability because oftentimes, the resource demand exceeds the supply. When resources are over-allocated, activities are delayed until resources become available. Due to the projects' size and complexity, schedulers use available software to solve the resource conflicts of a schedule. After testing Primavera P6 versions and MS Project v2016, both software create phantom float in a resource-constrained schedule. This is, the RCS calculations suggest that activities have float, but this float might not exist at all. Resource-Constrained Scheduling (RCS) techniques mitigate a resource supply-demand problem but fail to identify a project critical path. The methods do not consider the resource-activity dependencies that arise when activities are delayed due to resource limits. As a result, the critical path is broken, and all the activities must be considered as critical. To provide correct float values and a continuous critical path, the Resource-Constrained Critical Path (RCPM) was introduced by Kim and de la Garza in 2003. Regardless of the RCPM provides more reliable float values than traditional RCS-related algorithms, there are some shortcomings that must be addressed to enhance its capability. This study addresses the existing shortcomings of RCPM to make it more practical for real construction projects.

Diffusion Tensor Magnetic Resonance Imaging (DT-MRI), also known as Diffusion Tensor Imaging (DTI), is a unique medical imaging modality that provides non-invasive estimates of White Matter (WM) connectivity based on local principal directions of anisotropic water diffusion. DTI tractography estimates are a macroscopically sampled description of underlying microscopic structure, and are therefore of limited validity. The under-sampling of underlying white matter structure in DTI data gives rise to Intra-Voxel Orientational Heterogeneity (IVOH), a condition in which white matter structures of multiple different orientations are averaged into a single DTI voxel sample, causing a loss of validity in the diffusion tensor model. Fast Marching Tractography (FMT) algorithms based on fast marching level set methods have been proposed to better handle the presence of IVOH in DTI data when compared to older Streamline Tractography (SLT) methods. However, the actual performance advantage of any tractography algorithm over another cannot be conclusively stated until a ground truth standard of comparison is developed. This work develops an optimized version of the FMT algorithm that is dubbed the Front Propagation Tractography (FPT) algorithm. The FPT algorithm includes unique approaches to the speed function, connectivity estimation, and likelihood estimation components of the FMT framework. The performance of the FPT algorithm is compared against the SLT algorithm using ground truth software phantom data and human brain data. Software phantom ground truth experiments compare the performance of each algorithm in single tract and crossing tract structures for varying levels of diffusion tensor field perturbation. Human brain estimates in the corpus callosum yield qualitative comparisons from inspection of 3D visualizations. A final area of exploration is the construction and analysis of a ground truth physical DTI phantom manifesting IVOH. / Master of Science

Recent technology developments have made possible the creation of several commercial devices and a selected number of development platforms for the inclusion of haptics (the sense of touch) in virtual environments (VE). This thesis sought to investigate and develop a better understanding of whether or not haptics or sound substitutions improved manipulation performance or usability in VE applications. Twenty-four volunteers (12 males and 12 females) participated in a 2 (haptics) x 2 (sound) x 2 (gender) mixed factorial experiment in which they completed a VE manipulation task involving the assembly and disassembly of 5 interconnecting parts. Performance for the manipulation task was measured through completion time and the number of collisions made, as well as subjective measures of usability. Results indicated that completion times were slower and collision counts were higher for males with the addition of haptics (ptime = 0.03; pcollisions<0.05), while females exhibited a smaller increase in collision counts and no increase in completion time with the addition of haptics. Nonetheless, there were improved usability attributes when haptics were incorporated, more specifically, an increased sense of realism, perceived helpfulness and perceived utility in a design task (p<0.05 for all). Sound was found to be an effective substitute for haptics in most measures taken while the combination of sound and haptics versus either alone, did not demonstrate any signs of improving performance or any usability attributes. It is therefore recommended that sound substitution be used in VE manipulation tasks where the extra haptic information is desired, and minimizing completion time or collisions are the overall goal. Finally, for the utility of the feedback towards a design task, users ranked haptics as being more useful than sound, but ranked the combination of sound and haptics as being the best feedback condition (p<0.05). Further research is required to determine whether this belief is consistent with objective measures. / Master of Science

Laser therapies can provide a minimally invasive treatment alternative to surgical resection of tumors. However, therapy effectiveness is limited due to nonspecific heating of target tissue, leading to healthy tissue injury and extended treatment durations. These therapies can be further compromised due to heat shock protein (HSP) induction in tumor regions where non-lethal temperature elevation occurs, thereby imparting enhanced tumor cell viability and resistance to subsequent therapy treatments. Introducing nanoparticles (NPs), such as multi-walled nanotubes (MWNTs) or carbon nanohorns (CNHs), into target tissue prior to laser irradiation increases heating selectivity permitting more precise thermal energy delivery to the tumor region and enhances thermal deposition thereby increasing tumor injury and reducing HSP expression induction. This research investigates the impact of MWNTs and CNHs in untreated and laser-irradiated monolayer cell culture, tissue phantoms, and/or tumor tissue from both thermal and biological standpoints. Cell viability remained high for all unheated NP-containing samples, demonstrating the non-toxic nature of both the nanoparticle and the alginate phantom. Up-regulation of HSP27, 70 and 90 was witnessed in samples that achieved sub-lethal temperature elevations. Tuning of laser parameters permitted dramatic temperature elevations, decreased cell viability, and limited HSP induction in NP-containing samples compared to those lacking NPs. Preliminary work showed MWNT internalization by cells, which presents imaging and multi-modal therapy options for NT use. The lethal combination of NPs and laser light and NP internalization reveals these particles as being viable options for enhancing the thermal deposition and specificity of hyperthermia treatments to eliminate cancer. / Master of Science

Yes / Purpose Flicker-defined form (FDF) stimuli have recently been adopted for visual field testing. A key difference between FDF and traditional perimetric stimuli is that the entire display background contains flickering dots. The purpose of this study was to determine whether the perception of FDF stimuli is influenced by lateral interactions involving regions beyond the stimulus border in young healthy observers. Methods Experiment 1 measured the effect of surround size and retinal eccentricity on the detection of the FDF contour. Psychometric functions were collected for surround diameters of 20°, 30° and 40°, and with stimuli centred at eccentricities of 0°, 10° and 20°. Experiment 2 measured the effect of target-surround temporal phase difference on apparent temporal contrast (flicker strength) of the target for both the FDF stimulus and a solid-field stimulus. Psychometric functions were collected for target-surround phase differences of 0°, 45°, 90°, 135° and 180°. Results Our results show a mild surround-suppression effect for FDF stimuli that is independent of surround size. Magnitudes of FDF surround suppression were consistent with the reduced temporal contrast energy of the stimulus compared to solid-field stimuli. Conclusion FDF stimuli necessarily have both flickering target and background. Our results suggest that visual field defects outside the target are unlikely to markedly influence the detection and perception of the FDF stimulus. Nevertheless, mild surround suppression of contrast arises for FDF stimuli, hence interactions between the background and the target area may influence FDF results in conditions that alter centre-surround perceptual effects.

L’athérosclérose est une maladie qui cause, par l’accumulation de plaques lipidiques, le durcissement de la paroi des artères et le rétrécissement de la lumière. Ces lésions sont généralement localisées sur les segments artériels coronariens, carotidiens, aortiques, rénaux, digestifs et périphériques. En ce qui concerne l’atteinte périphérique, celle des membres inférieurs est particulièrement fréquente. En effet, la sévérité de ces lésions artérielles est souvent évaluée par le degré d’une sténose (réduction >50 % du diamètre de la lumière) en angiographie, imagerie par résonnance magnétique (IRM), tomodensitométrie ou échographie. Cependant, pour planifier une intervention chirurgicale, une représentation géométrique artérielle 3D est notamment préférable. Les méthodes d’imagerie par coupe (IRM et tomodensitométrie) sont très performantes pour générer une imagerie tridimensionnelle de bonne qualité mais leurs utilisations sont dispendieuses et invasives pour les patients. L’échographie 3D peut constituer une avenue très prometteuse en imagerie pour la localisation et la quantification des sténoses. Cette modalité d’imagerie offre des avantages distincts tels la commodité, des coûts peu élevés pour un diagnostic non invasif (sans irradiation ni agent de contraste néphrotoxique) et aussi l’option d’analyse en Doppler pour quantifier le flux sanguin. Étant donné que les robots médicaux ont déjà été utilisés avec succès en chirurgie et en orthopédie, notre équipe a conçu un nouveau système robotique d’échographie 3D pour détecter et quantifier les sténoses des membres inférieurs. Avec cette nouvelle technologie, un radiologue fait l’apprentissage manuel au robot d’un balayage échographique du vaisseau concerné. Par la suite, le robot répète à très haute précision la trajectoire apprise, contrôle simultanément le processus d’acquisition d’images échographiques à un pas d’échantillonnage constant et conserve de façon sécuritaire la force appliquée par la sonde sur la peau du patient. Par conséquent, la reconstruction d’une géométrie artérielle 3D des membres inférieurs à partir de ce système pourrait permettre une localisation et une quantification des sténoses à très grande fiabilité. L’objectif de ce projet de recherche consistait donc à valider et optimiser ce système robotisé d’imagerie échographique 3D. La fiabilité d’une géométrie reconstruite en 3D à partir d’un système référentiel robotique dépend beaucoup de la précision du positionnement et de la procédure de calibration. De ce fait, la précision pour le positionnement du bras robotique fut évaluée à travers son espace de travail avec un fantôme spécialement conçu pour simuler la configuration des artères des membres inférieurs (article 1 - chapitre 3). De plus, un fantôme de fils croisés en forme de Z a été conçu pour assurer une calibration précise du système robotique (article 2 - chapitre 4). Ces méthodes optimales ont été utilisées pour valider le système pour l’application clinique et trouver la transformation qui convertit les coordonnées de l’image échographique 2D dans le référentiel cartésien du bras robotisé. À partir de ces résultats, tout objet balayé par le système robotique peut être caractérisé pour une reconstruction 3D adéquate. Des fantômes vasculaires compatibles avec plusieurs modalités d’imagerie ont été utilisés pour simuler différentes représentations artérielles des membres inférieurs (article 2 - chapitre 4, article 3 - chapitre 5). La validation des géométries reconstruites a été effectuée à l`aide d`analyses comparatives. La précision pour localiser et quantifier les sténoses avec ce système robotisé d’imagerie échographique 3D a aussi été déterminée. Ces évaluations ont été réalisées in vivo pour percevoir le potentiel de l’utilisation d’un tel système en clinique (article 3- chapitre 5). / Atherosclerosis is a disease caused by the accumulation of lipid deposits inducing the remodeling and hardening of the vessel wall, which leads to a progressive narrowing of arteries. These lesions are generally located on the coronary, carotid, aortic, renal, digestive and peripheral arteries. With regards to peripheral vessels, lower limb arteries are frequently affected. The severity of arterial lesions are evaluated by the stenosis degree (reduction > 50.0 % of the lumen diameter) using angiography, magnetic resonance angiography (MRA), computed tomography (CT) and ultrasound (US). However, to plan a surgical therapeutic intervention, a 3D arterial geometric representation is notably preferable. Imaging methods such as MRA and CT are very efficient to generate a three-dimensional imaging of good quality even though their use is expensive and invasive for patients. 3D-ultrasound can be perceived as a promising avenue in imaging for the location and the quantification of stenoses. This non invasive, non allergic (i.e, nephrotoxic contrast agent) and non-radioactive imaging modality offers distinct advantages in convenience, low cost and also multiple diagnostic options to quantify blood flow in Doppler. Since medical robots already have been used with success in surgery and orthopedics, our team has conceived a new medical 3D-US robotic imaging system to localize and quantify arterial stenoses in lower limb vessels. With this new technology, a clinician manually teaches the robotic arm the scanning path. Then, the robotic arm repeats with high precision the taught trajectory and controls simultaneously the ultrasound image acquisition process at even sampling and preserves safely the force applied by the US probe. Consequently, the reconstruction of a lower limb arterial geometry in 3D with this system could allow the location and quantification of stenoses with high accuracy. The objective of this research project consisted in validating and optimizing this 3D-ultrasound imaging robotic system. The reliability of a 3D reconstructed geometry obtained with 2D-US images captured with a robotic system depends considerably on the positioning accuracy and the calibration procedure. Thus, the positioning accuracy of the robotic arm was evaluated in the workspace with a lower limb-mimicking phantom design (article 1 - chapter 3). In addition, a Z-phantom was designed to assure a precise calibration of the robotic system. These optimal methods were used to validate the system for the clinical application and to find the transformation which converts image coordinates of a 2D-ultrasound image into the robotic arm referential. From these results, all objects scanned by the robotic system can be adequately reconstructed in 3D. Multimodal imaging vascular phantoms of lower limb arteries were used to evaluate the accuracy of the 3D representations (article 2 - chapter 4, article 3 - chapter 5). The validation of the reconstructed geometry with this system was performed by comparing surface points with the manufacturing vascular phantom file surface points. The accuracy to localize and quantify stenoses with the 3D-ultrasound robotic imaging system was also determined. These same evaluations were analyzed in vivo to perceive the feasibility of the study.

Die Dissertation thematisiert die kontextbezogene Präferenzbildung von Konsumenten. Aufsatz 1 untersucht das Substitutionsverhalten von Konsumenten in Out-of-Stock Situationen unter Berücksichtigung des Einflusses von Promotions. Die Ergebnisse zweier Online-Studien zeigen, dass sowohl Phantome als auch Promotions die Dominanzstruktur eines Choicesets verändern und somit zu systematischen Verschiebungen der relativen Präferenzen führen. Aufsatz 2 diskutiert, ob Kontexteffekte in einem hypothetischen Entscheidungsumfeld mit rein imaginären Kaufentscheidungen im Vergleich zu verbindlichen Entscheidungen mit realen Zahlungen systematisch überschätzt werden. Die empirischen Resultate belegen, dass der Ähnlichkeitseffekt in hypothetischen Studien signifikant höher ist als in Erhebungen unter Verwendung von realen Marken und verbindlichen Kaufentscheidungen inklusive tatsächlicher Zahlungsverpflichtungen für die gewählten Produkte. Aufsatz 3 untersucht, ob der „reversed similarity effect“, als die Tendenz von Konsumenten bei der Nichtverfügbarkeit von bevorzugten Produkten solche Substitute zu wählen, die der nichtverfügbaren Wahloption ähnlich sind, auch in realen Entscheidungsgegebenheiten Gültigkeit besitzt und bestätigt dies anhand von zwei empirischen Studien. Aufsatz 4 analysiert den interaktiven Effekt von Phantomen und Händlerempfehlungen auf die Präferenzbildung bei Onlinekäufen. Es zeigt sich, dass der separate Einfluss beider Faktoren nicht zwangsläufig positiv interagiert. Vielmehr bedingen sich Richtung und Stärke der gemeinsamen Wirkung durch die jeweilige Produktkategorie sowie die empfundene Wichtigkeit der enthaltenen Produktattribute. Aufsatz 5 beschäftigt sich mit Präferenzdeterminanten für biologische Produkte. Mithilfe eines Strukturgleichungsmodells kann belegt werden, dass Gesundheits- sowie Umweltmotive keinen direkten Einfluss auf die Bio-Präferenzen eines Haushalts haben, sondern durch die jeweilige Einstellung zu Bioartikeln moderiert werden. / The doctoral dissertation analyzes context-dependent preference formation of customers with regard to the influence of product- and situation-specific as well as experimental factors. Essay 1 studies preference formation of customers in out-of-stock situations by coevally considering the specific influence of promotions. The results of two online studies reveal that both phantoms and promotions induce changes in the dominance structure of a choice set, thereby systematically affecting customers’ substitution decisions. Essay 2 discusses if context effects are significantly overestimated in binding choice settings that include real payments for test products. The attained results confirm that the similarity effect is significantly higher in purely hypothetical decision environments in contrast to realistic choice setting inclusive of payment obligations for the selected products. Essay 3 attends to the question if the reversed similarity effect – as a customers’ tendency to preferably select very similar substitutes when a desired item is temporarily unavailable – also holds true in market-like choice scenarios. The results of a comprehensive online study confirm the existence of the effect in all tested product categories. Essay 4 studies the interactive effect of phantoms, i.e. unavailable choice options, and recommendations on directing customers’ choice in online purchase decisions. It can be demonstrated that the factors’ separate influence does not necessarily add up when appearing within the same choice scenario. Instead boundary conditions of the factors’ interaction are identified. Essay 5 seeks to identify determinants of customers’ preference for organic products. The results of PLS structural equation modelling show that health- as well as environmental motives do not have a direct effect on relative preferences for organic items but that their influence is fully mediated by one’s attitude towards organically produced articles.