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  • 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.
181

Impact of a Barrier on Transport of Particles and Aerosolization of Viruses at a Wastewater Treatment Plant

Gnegy-Spencer, Mariah Ann 27 February 2023 (has links)
Airborne microorganisms, such as bacteria, viruses and fungi, are abundant in the natural and built environments. This research encompasses two studies on virus aerosolization and transport in the built environment and the subsequent implications for human health. In the first study, we quantified the impact of a barrier on the spatial distribution of different-sized particles released by speaking in a poorly ventilated room. The room was outfitted with 108 passive sampling sites. The barrier resulted in an increase in 0.5 µm particles deposited on the source-side of the barrier and an increase in 0.5 µm particles at other locations 4-6 m from the source. The barrier had minor impacts on the distribution of 1, 6, 10 and 20 µm particles. The results from this study indicated that barriers may not serve as adequate protection to others in the room, depending on their locations relative to the barrier and the timescale of exposure. In the second study, we reviewed the applications of next-generation sequencing for viruses in water environments. We also characterized the occurrence of two viruses (crAssphage and SARS-CoV-2) from a local wastewater treatment plant (WWTP) in both water and air samples at two locations within the WWTP (influent and aeration basin). We found that crAssphage, a fecal indicator, was quantifiable in most air and water samples, but was not detected in control samples. SARS-CoV-2 N2 RNA was detected in a fraction of the water and air samples but was present in the control water samples, so results for this virus are confounded by laboratory contamination. We also found that there was no correlation between airborne and waterborne SARS-CoV-2 concentrations at the WWTP. A quantitative microbial risk assessment model was constructed to determine inhalation risks associated with airborne SARS-CoV-2 for WWTP operators. The probability of infection ranged from about 2.4 x 10-4 to 5.6 x 10-8 and was heavily dependent on exposure time, airborne concentration and other parameters. / Doctor of Philosophy / Airborne microorganisms, such as bacteria, viruses and fungi, are abundant in the natural and built environments. This research encompassed two studies that evaluated the impact of viruses in the built environment on public health. The first study investigated whether a barrier, like Plexiglas, could protect people from another person's exhaled particles in a poorly ventilated room. The barrier resulted in an increase in the smallest particles (0.5 µm) on the same side of the barrier as the source and an increase in these particles at other locations 4-6 m from the source, indicating that individual exposure depends on their location relative to the barrier. The barrier had minor impacts on larger particles (1, 6, 10, and 20 µm). The second study focused on viruses at wastewater treatment plants (WWTPs). As part of this study, we reviewed how one can use knowledge about the DNA and RNA of viruses in water and wastewater. We also measured the amount of two viruses (crAssphage and SARS-CoV-2) in wastewater and in air surrounding the WWTP. We detected crAssphage, a virus that infects bacteria and a marker for human activity, in most wastewater and air samples. We also detected SARS-CoV-2 in some wastewater and air samples, but this virus was also present in some control samples, so laboratory contamination was an issue. Using the concentrations of airborne SARS-CoV-2, we constructed a computational model to estimate the risk of infection for SARS-CoV-2 inhalation for WWTP employees. Our calculations indicated that the risk of infection ranged from 2.4 x 10-4 to 5.6 x 10-8 and heavily depended on parameters such as exposure time and airborne SARS-CoV-2 concentrations.
182

Morphological Change of a Developed Barrier Island due to Hurricane Forcing

Smallegan, Stephanie Marie 25 April 2016 (has links)
An estimated 10% of the world's population lives in low-lying coastal regions, which are vulnerable to storm surge and waves capable of causing loss of lives and billions of dollars in damage to coastal infrastructure. Among the most vulnerable coastlines are barrier islands, which often act as the first line of defense against storms for the mainland coast. In this dissertation, the physical damage to a developed barrier island (Bay Head, NJ, USA) caused by erosion during Hurricane Sandy (2012) is evaluated using the numerical model, XBeach. Three main objectives of this work are to evaluate the wave-force reducing capabilities of a buried seawall, the effects of bay surge on morphological change and the effectiveness of adaptation strategies to rising sea levels. According to simulation results, a buried seawall located beneath the nourished dunes in Bay Head reduced wave attack by a factor of 1.7 compared to locations without a seawall. The structure also prevented major erosion by blocking bay surge from inundating dunes from the backside, as observed in locations not fronted with a seawall. Altering the timing and magnitude of bay storm surge, the buried seawall continued to protect the island from catastrophic erosion under all conditions except for a substantial increase in bay surge. However, in the absence of a seawall, the morpho- logical response was highly dependent on bay surge levels with respect to ocean side surge. Compared to the damage sustained by the island during Hurricane Sandy, greater erosion was observed on the island for an increase in bay surge magnitude or when peak bay surge occurred after peak ocean surge. Considering sea level rise, which affects bay and ocean surge levels, adaptation strategies were evaluated on the protection afforded to the dune system and backbarrier. Of the sea level rise scenarios and adaptation strategies considered, raising the dune and beach protected the island under moderate rises in sea level, but exacerbated backbarrier erosion for the most extreme scenario. Although an extreme strategy, raising the island is the only option considered that protected the island from catastrophic erosion under low, moderate and extreme sea level rise. / Ph. D.
183

In Defense of a "Third Place": How Reassembling the Boundaries of an Urban Military Installation can Maintain Security while Uniting the Community

DeIuliis, Peter James 10 September 2019 (has links)
"Regardless of the differences among their citizens, cities always define their community as against the outside world; a settlement with internal defense walls cannot be called a true community." Community Design and Culture of Cities, by Eduardo Lozano pg 5 Throughout the history of human civilization, no manmade structure has been used to defend territory more than the Wall. Walls have been used to delineate the edges of empires, separate communities, limit migration and provide protection from enemies. As a result, the Wall has become synonymous with imperialism, segregation, racism and isolationism. But what about instances when security outweighs all other concerns? Is there a way to use the wall to maintain defensible space without negatively impacting the greater community? In the case of a military installation located in an urban environment, this is a real issue. Walls which protect the sensitive content within, also serve to divide the community. These necessary physical barriers have the incidental consequence of segregating the servicemembers and government civilians within from the community which they serve. I contend that the thoughtful treatment of these barriers can create a "third place" ripe for interaction between the installation and the surrounding community. By designing retail, educational and cultural spaces along the border, the security of the installation can remain intact while also fostering an active relationship with its surroundings. After all, as Eduardo Lozano states, "a settlement with internal defense walls cannot be called a true community." / Master of Science / “Regardless of the differences among their citizens, cities always define their community as against the outside world; a settlement with internal defense walls cannot be called a true community.” Community Design & Culture of Cities, by Eduardo Lozano pg 5 Throughout the history of human civilization, no manmade structure has been used to defend territory more than the Wall. Walls have been used to delineate the edges of empires, separate communities, limit migration and provide protection from enemies. As a result, the Wall has become synonymous with imperialism, segregation, racism and isolationism. But what about instances when security outweighs all other concerns? Is there a way to use the wall to maintain security without negatively impacting the greater community? In the case of a military installation located in an urban environment, this is a real issue. Walls which protect the sensitive content within, also serve to divide the community. These necessary physical barriers have the incidental consequence of segregating the servicemembers and government civilians within from the community which they serve. I contend that the thoughtful treatment of these barriers can create a “third place” ripe for interaction between the installation and the surrounding community. By designing retail, educational and cultural spaces along the border, the security of the installation can remain intact while also fostering an active relationship with its surroundings. After all, as Eduardo Lozano states, “a settlement with internal defense walls cannot be called a true community.”
184

Finite Element Modeling of Occupant Injury Risk and Crash Performance of W-Beam Guardrail Barriers in Roadside Crashes

Wang, Qian 22 May 2009 (has links)
This thesis presents the results of a research effort aimed at investigating the crash performance of w-beam guardrail barriers in vehicle-roadside crashes using the finite element method. The developed roadside barrier models can be used to assess the occupant injury risk, vehicle performance, and damage to guardrail barriers during a roadside accident. The finite element models of w-beam guardrail barriers may also help evaluate the crash performance of the w-beam barriers with minor damage in vehicle-barrier crashes. Thus, the results can be used to develop repair guidelines to assist highway personnel in identifying levels of minor barrier damage and deterioration. Finite element models of the weak post w-beam guardrail barriers were developed and simulated using LS-DYNA. The simulation results were validated against full scale crash tests of pickup trucks and passenger cars impacting w-beam guardrail barriers. The maximum dynamic deflection of the guardrail, exit velocity and angle of the vehicle, and occupant injury risk were calculated and compared to the tests. Kinematics of the vehicle and guardrail were assessed qualitatively as well as quantitatively. The analysis showed that simulation results were in good agreement with test data. Additionally, the models were validated against pendulum tests conducted the Federal Outdoor Impact Laboratory (FOIL). Simulation results of pendulum tests showed that the test section taken from the current full scale models performed very similarly to that in the real pendulum tests. The developed finite element models were subsequently used to examine the crash performance of weak post w-beam guardrail barriers with minor damage under vehicle impacts. Only rail/post deflection based minor damage to weak post w-beam guardrail barriers was considered in this study. Simulations were completed to obtain the damaged profiles of the guardrail systems; the damaged weak post guardrail barriers were impacted by the pickup model at mid-span for the second time. The impacting vehicle remained stable in all of these simulations. No conclusions could be drawn however whether these second impacts could have resulted in rail tearing or rupture. / Master of Science
185

Model Development and Monte-Carlo Methods for the Simulation and Analysis of Coastal Impacts of Barrier Island Breach During Hurricanes

Jeffries, Catherine Renae 07 May 2024 (has links)
Barrier islands can protect the mainland from flooding during storms through reduction of storm surge and dissipation of storm generated wave energy. However, the protective capability is reduced when barrier islands breach and a direct hydrodynamic connection between the water bodies on both sides of the barrier island is established. Breaching of barrier islands during large storm events is complicated, involving nonlinear processes that connect water, sediment transport, dune height, and island width among other factors. In order to assess the impacts barrier island breaching has on flooding on the mainland, we modified a storm surge model, GeoClaw, to impose a Gaussian bell-curve on the barrier island that opens during a hurricane simulation and deepened over time. We added a new method of generating storm surge with storm forcing inputs in the form of wind and pressure fields to expand GeoClaw's current utilization of best track information so that storm forcing from planetary boundary layer models can also be utilized in simulations. We created a statistical method to assess the sensitivity of mainland storm-surge to barrier island breaching by randomizing the location, time, and extent of a breach event across the barrier island at Moriches, NY. My results show that total mainland inundation is affected by the changes in location, size, timing and numbers of breaches. Total inundation has a logarithmic relationship with total breach area and breach location is an important predictor of inundation and bay surge. The insights from this study can help prepare shoreline communities for the differing ways that breaching affects the mainland coastline. The model updates created can also allow others to use this framework to study differing regions. Understanding which mainland locations are vulnerable to breaching, planners and coastal engineers can design interventions to reduce the likelihood of a breach occurring in areas adjacent to high flood risk. / Doctor of Philosophy / Storm surge is one of the most deadly and expensive parts of a hurricane. Storm surge can be reduced if a barrier island exists near the mainland coastline. The sand dunes, beach vegetation, and size of the island aid in reducing the waves and storm-surge generated by large storms. When a barrier island breaches it causes a channel of water that connects the ocean and the bay that separates the island from the mainland. This channel of water allows waves and storm surge to be directly pushed into the bay, increasing the storm surge along the mainland coast. Breaching is complex with many factors such as dune size and total island width determining when or where a breach will form. In order to study how breaching affects the mainland during a hurricane, we chose a program that simulates storm surge from a hurricane, made a simple breaching calculation that opens a hole in a sand dune on a barrier island so that the ocean and bay are directly connected and the storm surge can pass through this hole, and enabled the program to use storm data that is pre-computed rather than generated during the simulation. In order to understand how breaching impacts the mainland coast at Moriches, NY, we simulated a hurricane and varied the number, size, and time of different breaches. We learned that total of all breach dimensions has a linear relationship to the amount of coastal flooding up to a threshold, where the breaches cover most of the island. Coastal communities can use the results of this study to determine where to put interventions in place that will reduce the impacts of barrier island breaching, update flood risk maps, and warn community members of changes in their location's risk assessment. Additionally, other regions with barrier islands nearby can use the software updates we created to study their own regions and assess different risk patterns than this study.
186

Development of a housing design features checklist for the disabled consumer with an evaluation of twenty-five apartments in Tucson, Arizona

Locke, Terrie Ann, 1956- January 1988 (has links)
This study develops a checklist of accessibility housing design features to aid the wheelchair user in evaluating apartments. It also evaluates relationships between accessibility and price, size, location, age, and subsidy of 25 apartments in Tucson, Arizona. Apartments were rated based on their adoption of the standards as set forth by the American National Standards Institute (ANSI) and the City of Tucson. Category A is those features specified by both agencies, Category B is those specified by ANSI only and Category C is those not specified. Category D is features not rated. A Total Rating Score is also given. A score of 80 was considered a minimum acceptable rating. Twenty percent of the apartments tested were found to be in compliance with the requirements of Category A, those features required by statute. Sixteen percent were in compliance with Category B and only four percent were in compliance with the other two categories. No significant relationships were found between accessibility and the five housing factors.
187

Head Trauma Release of Histamine from Dural Mast Cells Alters Blood-Brain Barrier: Attenuation with Zolantidine

Laufer, Susan R. 12 1900 (has links)
This study employed a new model of mild-to-moderate head trauma to specifically identify the role of dural mast cell (MC) histamine in trauma-induced increased permeability in the blood-brain barrier (BBB). A single line was scored partially through the left dorsal parietal skull. Immediately following the trauma, degranulation was seen in 39% of the MCs on the left and in 2% on the right. After a 20 min survival period, left duras showed 55% with MC degranulation (fewer with complete degranulation) compared to 34% on the right. In the other experiments two parallel lines were scored following the injection of Evan's blue. Histamine assay showed histamine increased in the left cortex to 154% at 5 min, 174% at 10 min, and 151% at 20 min. Fluorescent quantitation of extravasated Evan's blue at 20 min following the trauma gave an increase of 1385% over the value measured for the right cortex. Zolantidine, a selective histamine H2 receptor antagonist, administered at 10- and 20- mg/kg 30 min before the trauma blocked 65% of the Evan's blue extravasation compared with the control and 2.5 mg group.
188

Geomorphic Evolution of Caminada Pass in Southeast Louisiana.

Spizale, Jordyn A 06 August 2013 (has links)
Tidal inlets play a significant role in barrier island sustainability along the barrier islands of southern Louisiana. With increasing tidal prism, major changes are taking place within and adjacent to the inlets. The purpose of this thesis is to examine how Caminada Pass, a tidal inlet along the Caminada-Moreau headland, has evolved through time. Fundamental to this effort is evaluating which processes have contributed toward inlet evolution and what is the response of the inlet-bordering barrier island shorelines of Grand Isle and Elmer’s Island. This effort summarizes previous results and utilizes published bathymetric data, aerial photographs, vector shorelines, satellite images, and seafloor grab samples. The intent of this research is to document the variety of data that are available for future studies of Caminada Pass, an evaluation of long and short-term changes to the system, and an overall better understanding of the inlet dynamics of Caminada Pass.
189

In vitro metody pro predikci penetrace látek přes HEB / In vitro Methods for the Prediction of Blood Brain Barrier Penetration

Zálešáková, Helena January 2019 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Helena Zálešáková Supervisor: PharmDr. Marie Vopršálová, CSc. Title of diploma thesis: In vitro Methods for the Prediction of Blood Brain Barrier Penetration This thesis deals with the correlation between two in vitro models simulating the blood- brain barrier (HEB, hematoencephalic barrier) and their comparison in terms of practical use. These are the PAMPA (Parallel Artificial Membrane Permeability Assay) method and the MDCK (Madin-Darby Canine Kidney) cell line, which are models for potential central nervous system (CNS) penetration screening. Within this work, a set of sixteen standard drugs were measured. The procedure was similar in both methods in order to obtain information on the amount of test substances passing through the membrane from the donor portion of the plate to the acceptor. The concentration in the donor portion was measured by UV-VIS spectrophotometry. The main difference between these methods is the membrane through which the substances penetrate. In the case of PAMPA, a lipid solution that has been isolated from pig brain (PBL, polar brain lipid) is used. This lipid simulates the phospholipid membrane of the brain capillary endothelium. In the MDCK model, the membrane...
190

The Passage of Sodium-24 and Rubidium-86 Across the Blood-Brain Barrier System of Canines at Low Body Temperatures

Burgess, Michael Clifton 05 1900 (has links)
To evaluate the blood-brain barrier system in the pathogenesis of an irreversible hypothermic state in dogs, concentrations of 2 4 Na and 86Rb were measured at body temperatures ranging from 37 0 C to 160 C. A suppression of transport of sodium was demonstrated, followed by an increase as the temperature was lowered. The concentration of rubidium ion increased in concentration as the temperature fell. These data indicate there may be a temperature threshold below which the blood-brain barrier system fails to maintain the internal environment of the central nervous system. The intimate relationship of several brain stem nuclei with the cerebro-spinal fluid indicates they may be at risk during profound cooling.

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