University of Maryland, Baltimore County
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Digital Atlas of Megalopolis
No full textMegalopolis, Counties, States, Interstates, Economy, Population, Housing, Government, Education, Crime, Health, Employment, Immigratio
High Shear Rotary Membrane System Enhancements for Naval Wastewaters
No full textNavy ships are floating cities, requiring infrastructure and resources while generating various wastes: bilge water, black/graywater, industrial wastewaters and solid residuals. Treatment equipment selection is based not only on reliability, operational ease and cost but also on weight and cube. Current treatment systems would benefit from efficient solids removal; however, standard equipment has not been effective, necessitating developing improved technologies. Membranes systems simple operation and dependability fits shipboard requirements. The high shear rotary membrane system (HSR-MS) has shown a superior ability to remove contaminants and concentrate solids. However, low throughout confines the technology to applications without space limitations. The broad research goal seeks to overcome the throughput and space limitations allowing for shipboard HSR-MS implementation. HSR-MS often operates at high rotation (ω) to improve flux (J) by maximizing shear. However, an understanding of J, ω, diameter (D), and pressure provides conflicting relationships. A higher ω and larger D maximizes shear (increases J), but also increases rotationally induced backpressure (decreases J). This means membrane inner areas operate under the highest pressure and lowest shear; while membrane outer areas operate under the lowest pressure and highest shear (opposite of what is desired). To improve HSR-MS performance, J and/or D must increase. Larger D discs require operation with lower ω, leading to lost shear (decreased J). This work proposes employing continuous surface cleaning (CSC) and/or backpulsing (BP) to overcome reduced shear and lost J facilitating using larger D discs. Results showed J was highly dependent on ω and D. For every 100 rpm ω increase, J increased by 26 L/m2-hr. Flow (Q) was more sensitive providing ~1% increase in Q per mm D increase. The outer membrane third provided ≥ 50% of the total Q, while the inner third provided ~15%. Both BP and CSC produced higher J, proving most beneficial at lower ω. J improved by ~75% for ω500 rpm as flow conditions shifted from laminar to turbulent. Membrane inner area J improved with CSC or BP, but the outer area still produced the bulk of overall flow (~80%). Combing experimentally derived flux prediction models and BP/CSC flux improvements with commercially available membrane sizes show that larger D, slower ω discs can provide a 25-50% HSR-MS disc count reduction
Characterization of the Structure and the Nucleocapsid Protein Binding Properties of HIV-2 5'- Untranslated Region (5'-UTR) RNA: Implications of Diploid Genome Packaging
No full textAll retroviruses selectively package two copies of their full-length, unspliced RNA genomes, both of which serve as templates for strand-transfer mediated recombination during reverse transcription. Genomes are selected for packaging as dimers, and RNA elements that promote dimerization and packaging are both located within the 5�-untranslated region (5�-UTR) of the viral RNA. Studies indicate that dimerization of the HIV-1 genome is mediated by a self-complementary GCGCGC sequence located within the loop of a pseudopalindromic hairpin (DIS), and that long range base pairing between residues of the 5�-Unique element (U5) and those overlapping the gag start codon (AUG) promotes dimerization by stabilizing a DIS loop-exposed conformation. The DIS hairpin of the closely related HIV-2 5�-UTR has also been proposed to contain a self-complementary dimer-promoting loop (GGUACC) and a long-range U5:AUG helix, but dimerization and mutagenesis studies have led to suggestions that U5:AUG formation inhibits, rather than promotes, HIV-2 RNA dimerization. To address facilitate comparative mechanistic studies and as a step toward determining the structural basis for HIV-2 genome selection, we have conducted quantitative RNA dimerization studies of native and mutant forms of the HIV-2 5�-UTR RNA using constructs and conditions similar to those employed previously for HIV-1. As observed previously, the HIV-2 5�-UTR RNA forms a much weaker dimer than that observed for HIV-1 5�-UTR. Unlike HIV-1 5�-UTR RNAs, HIV-2 RNAs are kinetically labile and dependent on Mg2+. Tight dimers that are readily observed in the absence of Mg2+ were only observed for deletion mutants and are attributed to RNA misfolding. Our findings indicate that U5:AUG formation promotes dimerization, and this may be a common feature of this class of hominine lentiviruses. Experiments also suggest that NC protein promotes the labile dimer formation. However, no significant difference is observed between U5:AUG enabled and disabled RNA constructs in the number of high affinity NC binding sites and the NC:RNA disassociation constant. In addition, we have identified the high affinity NC binding sites downstream of the DIS and found that the structure requirement for the exposure of the high affinity NC binding site (SL3) is a hairpin structure of AUG region
Anomalous Diffusion in Subsets of Euclidean Space
No full textThe subject of this dissertation is anomalous (nonlocal) diffusion, a type of random motion which is important in statistical physics, fluid dynamics, the study of animal foraging patterns, and economics. In the main contribution of the dissertation, we construct a sequence of L�vy flight models on discrete spaces, based on previously existing models from statistical physics and the study of networks, and then use the Trotter-Kato theorem from semigroup theory to show that they converge to a continuum limit. In one special case, this continuum limit is a scaling limit from which we recover the well-known fractional diffusion model in Rn. In the general case, we obtain a model which evolves by means of multiscale random jumps in an inhomogeneous medium, represented by some subset of Euclidean space. On the one hand, this convergence theorem provides insight into the nature of L�vy flight models on lattices and networks, allowing us to show that they can exhibit surprising boundary effects as they approach the continuum limit. On the other hand, the convergence theorem is also a numerical method for solving nonlocal analogues to the heat equation with no-flux boundary conditions. The method applies to a large class of models for which, apparently, no practical approximation method which was known to be convergent previously existed. In addition, some of these results are extended to cover related nonlinear problems, which leads to new existence-uniqueness theorems for nonlocal reaction-diffusion systems. This is accomplished by formulating a sequence of approximating equations for which comparison principles and well posedness can be proved, and then showing that these desiderata are preserved in the limit. All this facilitates the analysis of nonlinear systems representing predator-prey dynamics and the spatial spread of epidemics, two areas where there is evidence that anomalous diffusion plays an important role but takes place in a bounded, heterogeneous environment, giving rise to models which fit well into the theoretical framework developed here
Effects of Employment on Mental Health for those with Severe Mental Illness
No full text"Clearer answers as to how employment affects both the mental health status and use of mental health services by those with a severe and persistent mental illness (SMI) will help states determine if and how such vocational services should be offered. Results may also inform the psychiatric treatment community of the significance (if any) that working has in one's overall treatment and recovery process. This study estimates the causal effect that employment has on two groups of outcome variables, 1) mental health status and 2) mental health costs, controlling for endogeneity. The same outcomes are used in assessing competitive and non-competitive employment. The two primary data sources are 1) the Outcomes Measurement Survey (OMS) for those using Maryland's Public Mental Health System (PMHS) and 2) Maryland PMHS claims data for the same persons and time period. The design is quasi-experimental, with a ""treatment"" group and a ""control"" group defined by employment status in the 2nd of 3 consecutive OMS interviews. Full information maximum likelihood (FIML) estimations simultaneously model the potentially endogenous employment status and the outcome variable. The population is persons with a SMI, covered through Maryland's PMHS between September 2006 and August 2009. Analyses are performed for the total population and separately for subpopulation groups defined by a) means of eligibility for PMHS coverage, b) duration receiving services at a mental health clinic prior to the study, and c) diagnosis groups. Outcome results are mixed, with mental health status not showing improvement, but total mental health costs being significantly decreased for those in the treatment group. Heterogeneity in treatment effects is observed for subpopulations and for different prior mental health scores. Finally, effects of competitive employment on mental health outcomes are significantly different and better than non-competitive effects. Policy implications are that vocational rehabilitation programs may have cost offsets in the form of reduced mental health costs. Analyses also show competitive employment is advantageous on mental health outcomes. Lastly, employment may have aggravating effects on mental health for some individuals, which is is motivation for better integration between mental health providers and vocational rehabilitation providers.
Generation of fluorescent strains to evaluate probiotic and pathogenic bacterial interactions in larvae of the Eastern oyster, Crassostrea virginica
No full textThe addition of probiotic bacteria to aquaculture system water or feed has proven effective at decreasing pathogen-induced mortality of fish and shellfish. The mechanisms by which host protection is achieved are being studied extensively, as the implications of probiosis to the aquaculture industry are substantial. The present study begins to assess the mechanisms used by an oyster probiotic Vibrio sp., OY15, in protecting its larval host, Crassostrea virginica, from a pathogenic Vibrio sp., B183. Plasmids harboring gfp and rfp were introduced into OY15 (named OY15g) and B183 (named B183r), respectively, forming fluorescent derivatives, which yielded unique genetic identifiers for each strain. Under non-selective conditions, plasmids were maintained faithfully for at least 72 hours. qPCR amplification assays were developed to measure gfp, rfp, and genes for 16S and 18S rRNA at 24, 48 and 72 hours during the course of an oyster challenge experiment. These experiments demonstrated temporal relationships between probiotic, pathogen, and total bacteria with their larval host and revealed that larval survival and mortality could be correlated to the presence or absence of probiotic and pathogen. Experiments examining the processes by which OY15g inhibits B183r activity included the growth of both bacteria in liquid media, which indicated that OY15g is capable of outcompeting B183r. In addition, OY15g supernatants were found to possess a factor(s) that destabilized B183r biofilm over time, suggesting a potential mechanism for OY15g probiosis. Furthermore, while quorum sensing N-acyl homoserine lactone (AHL) production could not be detected for OY15g by an Agrobacterium tumefaciens reporter assay, B183r was found to produce AHLs, suggesting that OY15g may influence B183r pathogenicity by interfering with AHL production
The United Workers: Toward a New Paradigm of Transformative Community-Labor Organizing
No full textIn this thesis I analyze the Baltimore-based poor people's human rights organization, the United Workers and its Transformative Community-Labor Organizing paradigm between 2002 and 2008. Accordingly, I analyze three areas. (1) The United Workers as a response to neoliberal capitalism and the declining role of trade unions. (2) The organization and its model as an attempt to offer a successful example of organizing under neoliberalism. That is, within the service and tourist sector, which is nearly devoid of formal working class organization, and working conditions are precarious. (3) The obstacles and achievements of the organization as demonstrated through its organizing model and the Living Wages Campaign at Camden Yards. The greatest obstacle comes in the form of a pedagogical tension, described as a rift in the group's pedagogical praxis. The achievements stem from the resolution of this tension, which offer new ways of approaching labor within neoliberalism. Much of the information on the United Workers presented derives from eight years of participant observations. An analysis of the three areas is produced using the works of Karl Marx, Friedrich Engels, David Harvey, Immanuel Wallerstein and Vanessa Tait's Poor Workers' Unions. They contribute to contextualizing the nature of class struggle, neoliberal capitalism, social movements, the decline of trade unions and the formation of community-labor organizations like the United Workers. Furthermore, the works of Antonio Gramsci, Paulo Freire, Willie Baptist and the Coalition of Immokalee Workers (CIW) are drawn upon as they influenced the United Workers in developing its pedagogy and organizing approach
A Multilayer Framework To Catch Data Exfiltration
No full textData exfiltration is the unauthorized leakage of confidential data from a particular system. It is a specific form of intrusion that is particularly hard to catch due to the most common cause: an insider entity who is responsible for the leak. That entity could be a person employed in the organization or a malicious hardware component bought from an unreliable third party. Catching such intrusions, therefore, can be extremely difficult. We describe a framework comprising multiple parameters that are constantly monitored in a system. These parameters can cover the entire stack of the computer architecture, from the hardware up to the application layer. Malicious behavior is detected by different modules monitoring these parameters and an aggregated attack alert is produced if multiple modules detect malicious activity within a short period of time. A more distributed and comprehensive monitoring framework should ensure that designing an attack becomes extremely difficult since an attack must go through multiple detectors present in the system without raising any alarms