University of Maryland, Baltimore County
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SYNTHESIS, CHARACTERIZATION, AND INCORPORATION OF BENZOPERYLENE MONOIMIDES INTO STIMULI-RESPONSIVE POLYACRYLAMIDE NANOGELS
No full textResearch into smart polymeric materials has shown promise in improving the quality of non-invasive temperature sensors. Smart polymers are materials that engineered to analytically respond to small changes in their local environment. In this work, we present research towards novel polymeric molecular thermometers as non-invasive temperature sensors with a ratiometric fluorescent read-out. The new smart polymer systems combine the thermo-responsive phase change behavior of polyacrylamide nanogel hosts with solvatochromic benzoperylene monoimide (BPI) fluorophore dopants. The individual components of the acrylamide-BPI molecular thermometers were studied with steady-state and time-correlated spectroscopies and dynamic light scattering. BPIs were synthesized via condensation of benzoperylene-1,2-dicarboxylic anhydride (BPA) in the presence of bulky primary amines. Structurally, an orthogonal orientation of sterically bulky imide substituents inhibits aggregation in solution and increases their versatility as fluorophores for analytical sensing. Absorbance spectra and geometry optimization of the BPIs show that at least 4 Å of distance is required of the imide substituent in order to prohibit planar stacking and aggregation. The BPIs exhibit strong UV absorbance (~80000 M-1cm-1) and fluorescence quantum yield (0.27 - 0.44) in many solvents. Large Stokes shifts are observed due to the asymmetrical substitution into the bay-region of the aromatic core. The BPI Stokes shifts were examined according to general and specific solvent models. It is determined that BPIs undergo a 3.9 D increase in dipole moment upon excitation and that protic solvents induce a more exaggerated fluorescence red-shift. The local polarity weakly influences the BPI ground state, but strongly influences the excited state. Fluorescent molecular thermometers were prepared via encapsulation of the BPIs within polyacrylamide nanogels. The water-insoluble BPIs were emulsified within the nonpolar gel network and the temperature-responsive fluorescent behavior was investigated. The BPI-doped acrylamides exhibit temperature-responsive fluorescence at the lower critical solution temperature (LCST) chain collapse of the polymers. Ratiometric emission intensity measurements of the nonpolar (500 nm) and polar (600 nm) BPI emission increased 4.7- to 14.4-fold at the LCST. Changing the acrylamide host compositions yielded molecular thermometers with response ranges spanning 27 °C to 60 °C with high sensitivity (32% C-1 to 51% C-1) at the LCSTs
Interaction of As(III), As(V) and PO4 with Fe Oxide Impregnated Activated Carbons: Modeling Multisorbate Adsorption using the Surface Complexation Approach
No full textThe adsorption behavior of As (III) as a function of pH on an iron oxide impregnated activated carbon (FeAC, 7% Fe(III) amorphous iron-oxide) at different adsorbate/adsorbent concentrations was modeled using the surface complexation approach. The surface complexation constants developed from single sorbate experiments successfully predicted competition between As(V) and As(III) and the surface complexation modeling (SCM) predictions were verified experimentally. The monoprotic surface site representation described the experimental data better than the diprotic representation. Based on surface complexation modeling simulations, L-Act had a higher affinity for As(V) than As(III). Significant As(III) oxidation to As(V) was observed at pH > 8. As(V) and As(III) removal by an iron oxide impregnated carbon (L-Act, 9% Fe(III) amorphous iron-oxide) over a range of environmental conditions using SCM approach was also investigated. L-Act surface complexation constants determined from single adsorbate systems were effectively used to predict pH dependent removal of As(V), As(III) and PO4 across a range of adsorbent/adsorbate ratios in single, binary and tertiary adsorbate systems and from a `National Sanitation Foundation' challenge water. As(V) and PO4 complexes were modeled as bidentate binuclear species at low pH and monodentate species at high pH; using the two monoprotic surface site representations with the diffuse electric double layer model (MDLM). For the bidentate-binuclear complexation, two approaches based on the value of the exponent (n) on [ NOH] in the mass action law (n = 1 or 2), produced similarly good results. In the tertiary system, the effect of PO4 on As(III) removal was more pronounced than on As(V) removal. As(III) oxidation to As(V) was observed for L-Act at pH > 8.5. The MDLM successfully predicted As(III)/As(V)/PO4 behavior for other amorphous iron-based adsorbents that were reported in the literature. The MDLM was also used to address other arsenic-related environmental questions such as the cost of L-Act required to treat water to target concentrations as a function of pH. The framework for a mechanistic model that describes the competitive adsorption between arsenic species and other compounds present in arsenic laden waters (e.g., PO4) has been developed and can be used by other researchers in describing their experimental data
Spirituality, Optimism and Self-Esteem: Pathways to Positive Change in a Women's Wellness Curriculum
No full textResearch indicates that women use alternative health treatments more than men (National Health Statistics Report [NHSR], 2008). However, it is unclear how these types of interventions improve women's lives. This research examined pathways to positive change among women in a holistic life improvement course offered by an alternative treatment setting, Shakti Rising. Participants were 218 women assessed at baseline and completion of an 8-week intervention designed to increase spiritual involvement and personal awareness through meditation, group discussion, journaling and meaning-making activities. Multiple regression analyses were used to explore the mediational role that changes in optimism played in the relation between changes in spirituality and self-esteem. Spirituality, optimism, and self-esteem increased significantly over the course of the 8-week intervention. Increases in optimism fully mediated the relation between increases in spirituality and increases in self-esteem. These results indicate that one possible pathway to improved self-esteem for women is via spirituality and optimism
Predictors of Readiness to Change in Victims of Intimate Partner Violence
No full textThis study examined demographic, psychological, and relational predictors of readiness to change in IPV victims as well as whether both victim and abusive partner readiness to change predicted subsequent abuse victimization. Data were collected via interview and self-report from 197 men who presented for counseling for relationship violence perpetration at a community agency and their female relationship partners. Results from bivariate correlations and multiple regression analyses indicated that greater PTSD symptoms, higher income, less contact with the abusive partner, and being separated were all related to greater victim readiness to change. After accounting for frequency of abuse, PTSD symptoms remained the only significant predictor. Neither partners' readiness to change predicted subsequent abuse victimization. Results highlight the need for further research defining readiness to change, for the clinical assessment of PTSD in IPV victims, and for future research on factors influencing safety from abuse
Heeding Hetch Hetchy: A Public History Project Exploring The National Interest in The Hetch Hetchy Valley, 1908-1913
No full textBetween 1908 and 1913, Congress debated whether to grant San Francisco the right to dam the Hetch Hetchy Valley. The Valley fell within Yosemite National Park, and was thus under the federal government's control. In this public history project, I focus on the petitions hundreds of citizens submitted to Congress regarding Hetch Hetchy. My main objective is to collaborate with the Center for Legislative Archives (CLA) at the National Archives and Records Administration in Washington, DC to create educational outreach materials based on these petitions. My thesis, therefore, consists of both an online component and a traditional paper. I have created a digital exhibition, which provides researchers with access to the petitions. The paper portion provides greater context for the petitions, and will be used by the education specialists at CLA to develop a lesson plan that can help teachers use the petitions in the classroom. By focusing specifically on the petitions, I demonstrate how the Hetch Hetchy debates illuminate the larger environmental arguments of the Progressive Era between utilitarian conservation and wilderness preservation. Furthermore, these petitions address larger themes of the Progressive Era, including the changing role of women in politics, the rise in lobbying, and the conflict between local and national interests
DIVERSITY AND INCLUSION MANAGEMENT: A HUMAN PERFORMANCE TECHNOLOGY APPROACH
No full textThe purpose of this study is to leverage the Human Performance Technology (HPT) approach as framework for effectively managing diversity and inclusion in an organizational setting. The author implements this approach to analyze performance issues related to diversity and inclusion in a non-profit organization focused on resolving the issues faced by a diverse at-risk youth population. The author then recommends a set of tailored and cost-effective interventions drawn from the HPT's comprehensive managerial concepts to the non-profit organization. This study suggests that HPT could be used as an effective and results-driven approach to individual and organizational performance challenges related to diversity and inclusion.  
Gleaning Bat Wing Morphology Using a Bag-of-Patterns Representation
No full textWe present research exploring the suitability of representing bat flight data as a bag-of-patterns for the purpose of training machine learning classifiers to predict bat flight speed. Bats are the only mammals capable of sustained flight and they make use of efficient flight strategies different from other flying animals. Today, a great effort is being made to understand the aerodynamic and kinematic characteristics of the wing as they may provide novel inspiration for aircraft design. In order to gain further insight into the characteristics of bat flight, we used the Symbolic Aggregate approXimation (SAX) algorithm. SAX produces a discrete representation of a time series, generating a bag (collection) of SAX words (local patterns). Researchers at Brown University recorded 3D locations of seventeen markers placed on joints along the bat wing of six species in flight in either a wind tunnel or flight corridor. We applied the SAX algorithm to a dataset of 104 bat flight runs, a new domain. Our experiments revealed that applying the SAX algorithm to the bat flight data does yield good representations for using classification algorithms to find structure in the data. Experiments also reveal that the markers along the leading edge of the wing are most significant in determining the speed of the flight
Visual ecology of signals and receivers: skin coloration and intraretinal opsin distributions in Lake Malawi cichlids
No full textVisual communication contributes to speciation through sexual selection in numerous, distantly related taxa. Sexual selection favors signals that are conspicuous to the intended receiver. The diverse African cichlid fishes offer a rich opportunity for investigating diversification. Although male cichlids appear conspicuous to the human eye, the spectral sensitivity and photic environment of cichlids differ from ours. In my dissertation I investigate cichlid color signals and the sensitivities of the retinas receiving these signals. First I ask whether male colors appear more conspicuous than female colors to cichlids in their environment. I use simple models of cichlid color space to compare cichlid colors and backgrounds that I measure with a spectrometer. Results indicate male colors are typically more conspicuous than female colors, consistent with the selective forces thought to act on each sex. However, in some species female colors are conspicuous, highlighting the need for further study of cichlid behavior. To facilitate analysis of numerous colors and backgrounds, the models assume cichlids are trichromatic. However, cichlid sensitivity may be more complex. Cichlids are known to express up to eight different opsin proteins in one retina, and this expression is influenced by the rearing light environment. Opsins help determine the spectral sensitivity of the photoreceptors in which they reside, yet their distribution in cichlid retinas is unknown. Using in situ hybridization and microspectrophotometry, I show that the cichlid Metriaclima zebra mixes different pairs of opsins in retinal regions that view distinct backgrounds. Opsin mixing increases sensitivity to the corresponding backgrounds, potentially aiding detection of dark objects. This is the first documentation of spectral tuning by opsin coexpression. However, my calculations show that coexpression of some opsins can hinder color discrimination, creating a trade-off between visual functions. By rearing M. zebra in different light conditions I found that the location as well as the relative proportion of opsins in the retina can be influenced by the environment. This suggests that developmental plasticity of opsin expression may contribute to the spectral tuning of retinal regions. Cichlids demonstrate that retinal sensitivity can be spatially heterogeneous and plastic and may affect signal evolution in undocumented ways
Understanding Latina Immigrant Mothers' Involvement in their Children's Preschool Education
No full textThe overall goal of the present study was to examine Latina immigrant mothers' involvement in their children's preschool education, including how they were involved, the factors that motivated their involvement, and whether they encountered barriers to being involved. Both quantitative and qualitative methods were utilized; this mixed-method approach allowed for an enriched, elaborated understanding of the parental involvement of Latina immigrant mothers. Forty-three foreign - born Latina mothers with children attending a bilingual urban preschool program were interviewed one time. Latina mothers supported their children's education in various ways, including forms of parental involvement that have been established (e.g., home-based, school-based, and home-school conferencing) as well as alternative cultural models of parental involvement that are embedded within cultural values and beliefs (e.g., apoyo, consejos, and sacrificios). The factors that motivate parents' involvement (i.e., self -efficacy, role construction, and invitation for involvement) varied by the form of involvement being examined. Specifically, mothers' reported self-efficacy was related to home-based involvement. Knowledge and skill was related to school-based involvement. Mothers reported lacking time and energy due to work demands and schedules as the main barrier to their involvement. The findings of the present study highlight the need to understand the ways Latina parents support their children's education that may be informed by cultural values and community norms. By doing so we will acknowledge a more diverse set of parental involvement behaviors than are typically examined in research and visible to teachers. An expanded definition of parental involvement may be used to inform programs that seek culturally and contextually appropriate ways to engage Latina immigrant families in their children's education
