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Wave-driven reverse osmosis desalination systems can be a cost-effective option for providing a safe and reliable source of drinking water for large coastal communities. Such systems usually require the stabilization of pulsating pressures for desalination purposes. The key challenge is to convert a fluctuating pressure flow into a constant pressure flow. To address this task, stub-filters, accumulators, and radially elastic-pipes are considered for smoothing the pressure fluctuations in the flow. An analytical model for fluidic capacitance of accumulators and elastic pipes are derived and verified. Commercially available accumulators in combination with essentially rigid (and low cost) piping are found to be a cost-effective solution for this application, and a model for selecting accumulators with the required fluidic-capacitance for the intended system is thus presented., S. D. Bechtel, Jr. Foundation, MIT Energy Initiative

This mixed methods study examined the congruency of the expected occurrence of leadership behaviours held by managers and those held by instructors in a Canadian college setting. The primary question was, “How congruent are the expectations on the occurrence of leadership behaviours between managers and instructors?” The study looked to answer why the expectations were congruent or not and what factors played into the level of congruency or lack thereof. The investigation used a mixed methods approach, combining a statistical analysis of a Likert-style survey measuring the expected occurrence of 30 leadership behaviours and a qualitative analysis of five open-ended follow-up questions to provide additional context to the statistical findings. The study found congruence of the expected occurrence of leadership behaviours for managers and instructors on the 30 measured leadership behaviours. However, the study also revealed that managers and instructors expressed concerns about how the expectations were met. Organizational structures were crucial to driving these expectations in the college system used in this study and played a central role in explaining the differences in expectations. Recommendations include leveraging the results of the study to improve organizational structures and to build stronger relationships within the organizations. Utilizing the Leadership Practices Inventory as a strategic planning tool and conducting additional research that looks into the impact organizational structures and processes have on leadership behaviours are further recommendations. Duplicating the study at similar institutions between all levels within the organizations to confirm its findings found is also recommended. Keywords: leadership behaviours, congruency, organizational structures, expectations

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, February 2007., This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections., Includes bibliographical references (leaves 139-142)., A fundamental question in neuroscience is how sensory information is represented in the brain. In particular, what principles guide the spatial organization of neurons with regard to their receptive field properties, and how is this organization established mechanistically? The visual cortex serves as a model area to address these questions, but whether general principles can explain the layouts of cortical maps, such as those of visual space and of specific response features, remains unresolved. We find that in primary visual cortex of ferret, the layout of each map is inter-dependent with that of the others. First, we find a strong anisotropy in the visual map, such that receptive field positions change more rapidly along one axis of cortex; and importantly, along the axis where visual space changes rapidly, the feature maps of orientation, ocular dominance, and spatial frequency change slowly. Second, orientation, ocular dominance, and spatial frequency maps have local spatial relationships with each other: in areas of cortex where one feature changes rapidly, the other features change more slowly. Each of these relationships are well-explained by a dimension-reduction model of cortex., (cont.) This suggests that the constraints which drive map formation in the model, continuity (representing each feature smoothly across cortex) and coverage uniformity (representing each feature combination to an equal extent), may play a central role in determining the functional organization of visual cortex. To explore the mechanisms giving rise to the map relationships, we alter the expression of one feature map early in development and measure the impact on the layouts of the remaining maps. We find that alteration of the ocular dominance map, due to neonatal monocular enucleation, does not prevent the formation of the orientation and spatial frequency maps, but it does alter their spatial relationships. The highest gradient regions of the spatial frequency map have a stronger tendency to avoid high gradient orientation regions, and the contours of the two maps have a greater tendency to cross orthogonally. The results are consistent with the predictions of a dimension-reduction model for removing a feature map, suggesting that as a result of altered input patterns, the cortex can rearrange over the time scale of development according to a dimension-reduction strategy., by Brandon J. Farley., Ph.D.

In the laboratory we have access to the massive Coulomb three-body systems D++D++D- and H++H ++H-. The systems are produced through collisions of 4.0 keV [special characters omitted] and [special characters omitted] on He, producing three charged fragments in the continuum. The long-range Coulomb inter action between the fragments can lead to highly correlated motion. The laboratory frame energies and scattering angles of the three fragments are measured in triple coincidence. Transforming to the center of mass (c.m.) frame, the c.m. energies and mutual correlation angles can be determined for each measured three-body event. When the observed triple events are plotted on a WYJ Dalitz plot as a function of total c.m. energy, patterns and trends develop in the experimental data. To understand the physical origins of these patterns, a series of classical numerical simulations of three charged bodies was executed modeling the [special characters omitted] and [special characters omitted] post-dissociation dynamics. The experimental data can then interpreted within the classical simulation framework combined with the quantum mechanical properties of the parent [special characters omitted] and [special characters omitted]. New insights has been gained on the dynamics of polar N-body systems. A new, heretofore unconsidered dissociation channel has been discovered where tenuous temporary associations between oppositely charged fragments can form. These Keplerian-like two-body systems lead to a rich domain of post-dissociation dynamics. Predicted by the three-body simulations, evidence of this novel dissociation process has been identified in the experimental data.