Economic effects of the Agricultural adjustment administration program on the Puerto Rican sugar cane industry, 1933-1947

Thesis (M.B.A.)--Boston University, 1948. This item was digitized by the Internet Archive

SmartFit web application interface

Part of the web application interface of a bigger project used to remotely monitoring by a supervisor of certain health signals for the purpose of patients diagnosis and computer aided therapy. This part is used to monitor the relations of the background servers responsibles to treat the signals

Economic effects of the Agricultural adjustment administration program on the Puerto Rican sugar cane industry, 1933-1947

Thesis (M.B.A.)--Boston University, 1948. This item was digitized by the Internet Archive

Modeling Form Roughness Induced by Tidal Sand Waves

Tide-dominated sandy shelf seas, such as the Dutch North Sea, are covered by sand waves. Yet, basin-scale hydrodynamic models do not include any sand wave information because their grid sizes are too coarse to resolve sand waves individually. We explore the possibility of parametrizing the effects of sand waves on the larger-scale tidal flow by means of a form roughness. Specifically, our aim is to see to what extent the flow over a sand wave field can be reproduced by that over a flat seabed with an increased effective roughness (accounting for both grain and form roughness). To do so, we use two process-based hydrodynamic models: a second order perturbation approach, and Delft3D. Both models demonstrate that the presence of sand waves causes amplitude decrease and phase shift of the tidal flow. We explore the dependencies of form roughness on different sand wave characteristics (wavelength, height and asymmetry). Shorter and higher sand waves cause a higher form roughness, while our analysis does not reveal any dependency on sand wave asymmetry. Notably, the consideration of a tidal flow, characterized by several tidal constituents, each represented by an amplitude and a phase, results in a more complex form roughness analysis than in a fluvial setting, where the flow is unidirectional and steady. We thus obtain an amplitude-based form roughness and a phase-based form roughness, each yielding a different value, yet displaying the same qualitative dependencies

The Effect of Endogenous Expression of HIV-1 gp120 on Glutamate Metabolism in Human Astrocytes

Human immunodeficiency virus (HIV) infection is a global epidemic that targets the immune system. HIV infects white blood cells and spreads throughout the entire body via blood stream and makes its way to the brain. HIV infection in the brain may lead to HIV associated neurocognitive disorders (HAND). To be able to address this problem, we have to better understand how HIV infection damages neurons. We hypothesize that gp120 causes neurotoxicity in the cells by inhibiting the conversion of glutamate to glutamine by glutaminase. As a result, glutamate concentrations will build up both inside and outside the cell causing excitatory neurotoxicity. To better understand this process, we transfected human astrocytes (U87MG cells) with mock (control), an empty vector (control), and with gp120 plasmid. Seventy-two hours post transfection, the cells were collected and run through a series of tests including SDS-PAGE/Western Blot and qRT-PCR to assess protein and mRNA levels of glutaminase and gp120. We expect production of gp120 by astrocytes to lead to a decrease in expression of glutaminase. This would inhibit the process of converting glutamate to glutamine and explain how excess of glutamate accumulates inside and outside of the cell causing neurotoxicity and cell death. In conclusion, we expect to find a direct relationship between gp120 and the glutamate metabolism in human astrocytes. Understanding the effect gp120 has on neurons will help develop more effective treatments to better fight the virus

Nucleation of helium in liquid lithium at 843 K and high pressures

Fusion energy stands out as a promising alternative for a future decarbonised energy system. In order to be sustainable, future fusion nuclear reactors will have to produce their own tritium. In the so-called breeding blanket of a reactor, the neutron bombardment of lithium will produce the desired tritium, but also helium, which can trigger nucleation mechanisms owing to the very low solubility of helium in liquid metals. An understanding of the underlying microscopic processes is important for improving the efficiency, sustainability and reliability of the fusion energy conversion process. The spontaneous creation of helium droplets or bubbles in the liquid metal used as breeding material in some designs may be a serious issue for the performance of the breeding blankets. This phenomenon has yet to be fully studied and understood. This work aims to provide some insight on the behaviour of lithium and helium mixtures at experimentally corresponding operating conditions (843 K and pressures between 108 and 1010 Pa). We report a microscopic study of the thermodynamic, structural and dynamical properties of lithium–helium mixtures, as a first step to the simulation of the environment in a nuclear fusion power plant. We introduce a new microscopic model devised to describe the formation of helium droplets in the thermodynamic range considered. Our model predicts the formation of helium droplets at pressures around 109 Pa, with radii between 1 and 2 Å. The diffusion coefficient of lithium (2 Å2/ps) is in excellent agreement with reference experimental data, whereas the diffusion coefficient of helium is in the range of 1 Å2/ps and tends to decrease as pressure increases.Postprint (author's final draft

Gradual Inlet Expansion and Barrier Drowning Under Most Sea Level Rise Scenarios

The expected increase in rates of sea level rise during the 21st century and beyond may cause barrier islands to drown. Barrier drowning occurs due to a sediment imbalance induced by sea level rise, causing inlets to open and expand. It is still unclear how fast barrier islands can drown. To gain insight into the morphodynamics of barrier systems subject to sea level rise, we here present results obtained with a novel barrier island exploratory model, BarrieR Inlet Environment-Drowning, that considers inlet expansion beyond equilibrium size. We quantify how much of a barrier island chain is drowned by calculating the fraction of its length that is below mean sea level due to sea level rise. Results show that barrier drowning is mostly sensitive to the wave height and the rate of sea level rise. In the model, it takes 100s of years for barrier islands to start drowning in response to high rates of sea level rise (more than 5 mm/yr, for a typical coastal environment). This lag in barrier response is caused by a gradual decrease in the sand volume of the barrier. Higher rates of sea level rise cause earlier and more severe barrier drowning. Modeled barrier systems that face higher waves undergo more frequent inlet closures that lower the rate of drowning, but they also have a deeper shoreface that increases the rate of drowning. In model simulations, the latter process dominates over the former when sea level rise rates exceed 5 mm/yr. Model results fairly agree with available field data