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Content and Effects of Facebook Breastfeeding Support Groups for WIC Mothers
Get PDFBreastfeeding inequity in the United States is a significant public health concern, with low-income women facing disproportionate challenges that contribute to lower rates of breastfeeding, highlighting a critical need for targeted support and intervention strategies. This dissertation explores the transformative potential of Facebook Breastfeeding Support Groups (FBSGs) in supporting low-income women, particularly participants in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), in their breastfeeding journey. Comprising three papers, the study adopts a multifaceted approach to unpack the dynamics of FBSGs in promoting and supporting breastfeeding. The first paper leverages the Uses and Gratifications Theory, analyzing the content of posts made by participants and administrators as well as the interactions among them mediated through the posts. The second and third papers are grounded in the Integrated Behavioral Model. In the second paper, a focus group study was conducted to gather rich, in-depth insights from WIC participants and administrators. The third paper adopts a quantitative approach, utilizing a cross-sectional survey to assess the association between the level of FBSG participation and breastfeeding duration with social support and self-efficacy as mediating variables. The first paper reveals that active participation and posts about breastfeeding-related experiences increase community interaction. The second paper emphasizes FBSG's role in fostering positive breastfeeding attitudes and underscores participants' preference for lactation consultants as group administrators. Lastly, the third paper indicates positive associations between higher levels of FBSG participation and breastfeeding social support and self-efficacy among WIC participants. This dissertation demonstrates the effectiveness of FBSGs in aiding WIC participants and elucidates the mechanisms through which FBSGs promote breastfeeding among low-income women
A Hydrologic and Geochemical Assessment of Potential Groundwater Contamination and Vadose Zone Attenuation at the Caselton Tailings Impoundment; Lincoln County, Nevada, USA
No full textDisposal of tailings material from the processing of lead, zinc, and silver sulfide ores as well as manganese oxide ores in the unlined Caselton Wash from 1941-1968 has created a potential source of groundwater contamination. However, the alluvial soils underlying the tailings impoundment are likely to provide significant natural attenuation of any acid mine drainage generated from the mine tailings, due to a relatively high carbonate content. The overarching goal of this project was to investigate the likelihood of possible impacts to groundwater quality from percolation of tailings-derived leachate through the Caselton Wash Tailings and the underlying alluvium. In addition, this study seeks to identify possible attenuation mechanisms for contaminants of concern which were identified in tailings leachates. To assess the likelihood of groundwater contamination, a field, laboratory, and modeling-based research program was conducted.Hydraulic properties were characterized through a combination of field infiltration measurements and laboratory characterization. Surface tailings material, as well as tailings material from subsurface borings were collected for use in laboratory experiments, and representative synthetic leachates were created in the laboratory from the collected tailings material. In addition, two monitoring well borings were drilled and one monitoring well was installed at the Caselton Wash site to determine the groundwater level and groundwater chemistry, both upgradient and downgradient of the tailings impoundment. Clean alluvial soils were collected during drilling of the upgradient well for use in laboratory column and beaker scale batch reaction experiments. The geochemical composition of sulfide tailings, Mn-oxide tailings, and alluvial soils were characterized using acid-base accounting, whole rock geochemistry analyses, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy.Attenuation of contaminants in tailings leachates by the alluvial soil was assessed through bench scale laboratory batch reaction experiments, as well as a reactive column experiment. Batch reaction reconnaissance experiments were conducted prior to performance of the column experiment to assess possible attenuation mechanisms, and to inform column experiment design. Conservative transport properties of the alluvium were assessed using NaCl and deuterated water column tracer experiments, while reactive transport was assessed by infiltrating columns of clean alluvial soil with tailings leachate that was dosed with a deuterated water tracer. During the reactive column experiment, probe-based measurements of pH, specific conductance, dissolved oxygen, and oxidation-reduction potential were continuously monitored in the column effluent, and samples were periodically collected and analyzed for Nevada Division of Environmental Protection Profile III analytes. Data from the batch reaction and reactive column experiments, including probe measurements, mass balance measurements, analytical chemistry analyses of column effluent for dissolved ions and deuterium, and geochemical analyses of residual solids were utilized for detailed geochemical interpretation and identification of potential attenuation mechanisms.Information from field characterization, laboratory experiments, and publicly available datasets were integrated to support the construction of hydrologic and conservative contaminant transport models of water movement and contaminant transport within the tailings impoundment and the underlying alluvium. As sulfate was identified to be the major contaminant of concern, and the reactive column experiment suggested that sulfate concentrations would remain elevated in the alluvium, a transport analysis of sulfate was undertaken. Pore water velocities from the hydrologic model were used as inputs for a conservative transport analysis of sulfate from the tailings impoundment through a section of unsaturated alluvium to a hypothetical water table at 150 m depth below the ground surface, and predicted a mean travel time of 10.1 years, with sulfate concentrations predicted to reach 95% of the source concentration after 19.0 years.From a hydrologic perspective, the most important result of this study was an increased understanding of the tailings impoundment hydrology. Specifically, the hydrologic sources and sinks of the tailings impoundment were identified, and it was clearly shown that run-on of water to the tailings impoundment from upslope areas comprised a significant portion of the water entering the tailings impoundment. The results of the hydrologic model also suggested that collection of leachate within excavated pits present on the surface of several tailings ponds could be increasing the amount of leachate that infiltrates the unsaturated zone compared to an undisturbed tailings surface.From a geochemical perspective, the most important results were the identification of several contaminants of concern, and the identification of their probable attenuation mechanisms in the unsaturated zone. From an analysis of the geochemical compositions of the tailings and tailings leachates, aluminum, antimony, arsenic, beryllium, cadmium, copper, iron, lead, manganese, selenium, zinc, fluoride, and sulfate were identified as contaminants of concern. Except for sulfate, all contaminant concentrations in the leachate were significantly reduced through interaction with the alluvial solids. Results from the batch reaction and reactive column experiments indicated that all contaminant concentrations except for antimony, arsenic, manganese, selenium, and sulfate were reduced to below drinking water standards in the column effluent. However, sulfate was the only contaminant that remained significantly elevated above drinking water standards �" the others were only slightly elevated above standards.Attenuation mechanisms related to the precipitation of, co-precipitation with, and sorption on to hydrous ferric oxide minerals were probably the most important attenuation mechanisms for the contaminants of concern identified at the Caselton tailings impoundment, and these mechanisms probably account for most of the attenuation capacity in the alluvial sediments underlying the tailings impoundment. Additional attenuation mechanisms that probably took place were the precipitation of some contaminant-bearing secondary minerals, and the precipitation of some carbonate solid solution minerals that contained contaminants of concern
Career Technical Education, Academic Achievement, and Behavioral Engagement
No full textCareer technical education (CTE) in the 21 st century has been a highly visible component of the American public educational framework, with the majority of graduates estimated to have taken at least one CTE course during their time in school. Yet as CTE continues to benefit from atypically broad levels of support in both legislative circles as well as the general public, its association as an educational model with positive results for students remains equivocal in scholarly research. A quantitative research methodology was used to guide the purpose of this study, which was to investigate the relationship between students' exposure to CTE programs and positive academic and behavioral outcomes over the course of four successive graduate cohorts. The research questions were: (a) Do statistically significant differences exist in on-time graduation status between groups of graduates who take only the first year of one or more CTE programs of study, who concentrate in one or more CTE program of study, and who take no CTE courses? (b) Do statistically significant differences exist in Composite ACT scores between groups of high school graduates who take only the first year of one or more CTE programs of study, who concentrate in one or more CTE program of study, and who take no CTE courses? (c) Do statistically significant differences exist in number of days attended between groups of high school graduates who take only the first year of one or more CTE programs of study, who concentrate in one or more CTE program of study, and who take no CTE courses? (d) Do statistically significant differences exist in total incidents of exclusionary discipline between groups of high school graduates who take only the first year of one or more CTE programs of study, who concentrate in one or more CTE program of study, and who take no CTE courses? (e) Do statistically significant differences exist in academic and behavioral variables between groups of high graduates who take varying levels of CTE, while controlling for gender, race, and special population designation? Results from this study revealed that exposure to CTE does associate at a level of statistical significance with positive academic and behavioral outcomes. While the strengths of associations were determined to be relatively low, results were consistent for all four years of data as analyzed. Students who took two or more years of one or more CTE programs (concentrators) were found to have had a significantly higher likelihood of graduating on time, while students who took only the first year of one or more programs (participants) were more likely to demonstrate improved behavioral engagement and achieve a higher composite score on the ACT assessment. The results suggested that CTE programming in a broad context has the potential to serve as an integral part of a comprehensive educational system, being consistently associated with an increased likelihood of positive academic and behavioral outcomes for students. It is recommended that educational practitioners consider how CTE programs can meet the unique academic and behavioral needs of their respective educational systems, relative to the methods and findings surfaced in this study. Furthermore, it is recommended that researchers in this space focus next on how student outcomes relate to CTE exposure at a more granular level, considering program type and quality of implementation. Ultimately, this study serves to shed light on the relationship of CTE exposure to positive student outcomes, highlighting the complexity of measurement while providing a foundation for further inquiry aimed at enhancing educational systems through evidence-based CTE programming
Fatigue behavior of 316L stainless steel plate specimens with two opposing surfaces processed by surface mechanical rolling treatment
No full textSurface mechanical rolling treatment (SMRT) was used to fabricate a gradient nanostructure on the surface layers of 316L stainless steel plate specimens which were then subjected to fully reversed strain-controlled tension-compression fatigue experiments to study the fatigue behavior. SMRT is a surface process utilizing repeated and deep rolling at a high strain rate, which results in a nano-grained thin layer near the surface of the processed workpiece. The plate specimen has a cross section of 7.0mmx5.5mm, with only two opposing surfaces processed by SMRT. The grain sizes of the nanostructured surface layer range from 30 nm to 300 nm while the coarse-grained base material has an average grain size of 70 μm. The stress-life fatigue curves show a significant enhancement of fatigue strength due to the surface process. The strain-life fatigue curve of the plate SMRT specimens is practically identical to that of the base material, which is very different from previous studies where round SMRT specimens were tested. When a strain amplitude is lower than 0.4%, fatigue cracks are found to initiate in the base material. Cracks are initiated in the SMRT layer when the strain amplitude is higher than 0.4%. Unlike round specimens where the strain-life curve displays a distinguishable kink point at the demarcation strain amplitude of 0.4%, the strain-life curve of the plate specimens does not clearly show such a kink point. The difference between the results of the round specimens and those of the plate specimens is attributed to the difference in stress state. The results of the current study confirm the fatigue mechanisms of a component consisting of materials of different fatigue properties
Atmospheric Water Harvesting Using Thermoelectric Peltier Coolers: Single Module and Prototype Characterizations and Design
No full textAtmospheric water harvesting is a promising technology that offers a sustainable solution to the water scarcity problem faced by many regions around the world. By collecting water vapor from the air, it provides an alternative source of clean drinking water, especially in arid and semi-arid areas where conventional water sources are limited. One of the key challenges in atmospheric water harvesting is the need for efficient cooling systems to condense the water vapor from the air. In this regard, thermoelectric coolers have emerged as a promising technology to enhance the performance of atmospheric water harvesters because they are reliable and low maintenance. Unlike traditional cooling systems that rely on mechanical components such as compressors and refrigerants, thermoelectric coolers have no moving parts, making them less prone to wear and tear. This results in a more robust and long-lasting cooling system for atmospheric water harvesters, which is crucial for an effective and sustainable operation, particularly in remote and off-grid locations. Therefore, a fully developed atmospheric water harvesting prototype is designed utilizing thermoelectric coolers to harvest atmospheric water and it can easily adapt to solar photovoltaics as a power source. The prototype is the size of a desktop coffee-machine and can be scaled-up to address different applications that will address the water challenge for today and tomorrow, in Nevada
High-elevation tree mortality shifts plant phenology in the Central Sierra Nevada
Get PDFLarge-scale tree mortality events are increasing in frequency and severity across the globe. Given that hotter and drier droughts are projected to continue with climate change, the cascading ecosystem level impacts of overstory canopy mortality may have unforeseen consequences on understory plant communities. Following a recent wave of drought-driven tree mortality events in the Central Sierra Nevada region, we investigated the potential impact of canopy cover loss at treeline on microsite conditions, and how this loss may impact the phenology of corresponding understory plant species. We asked: 1) Does a treeline mortality event create differing microsite conditions and influence plant community diversity? 2) is tree mortality altering understory plant phenology?, and 3) does the loss of canopy cover associated with tree mortality alter understory plant growth and morphology? To answer these questions, we monitored forb phenology weekly throughout the growing season, as well as annual diversity and PAR (photosynthetic active radiation) measurements, at 1m2 microsite plots under dead trees, live trees, and adjacent open areas at three high elevation study sites with varying levels of tree mortality in the Central Sierra Nevada in two drastically different climate years: 2022 and 2023. We found that microsite plots under dead trees had higher PAR values relative to those under live trees. Plants under dead trees showed earlier timing of key flowering phenological events relative to those under live trees. In addition to effects of tree canopy cover, date of first flowering and flowering duration were highly linked to site, temperature and snow depth, consistent with findings from many other high-elevation study systems. Furthermore, our study period covered two contrasting water years, and we observed diverging responses to weather on the species level as well as site- and year-level differences in phenology that were large relative to microsite differences. In the greenhouse we observed higher emergence rates for plants grown under a live shading treatment, though plants had higher total biomass in an open or no shade treatment. Monitoring changes in understory plant communities following large tree mortality events is important for understanding the effects on relationships with co-evolved pollinators and can provide insight to future changes in forest and plant community composition under novel climate conditions
An Analysis of Serotype-Specific Virulence in the Group A Streptococcus
Get PDFGroup A Streptococcus (GAS or Streptococcus pyogenes) is a Gram-positive coccus responsible for a wide range of human diseases, from mild infections such as pharyngitis/strep throat to invasive infections such as puerperal sepsis and necrotizing fasciitis. GAS results in nearly 500,000 annual fatalities, with invasive infections and acute rheumatic fever/rheumatic heart disease (ARF/RHD) being the primary causes of death. The burden of invasive GAS diseases is high, with ~650,000 cases and ~150,000 deaths annually. GAS strains are divided into more than 200 emm-types/M-types/serotypes based on the molecular typing of the sequence of the hypervariable N-terminal region of the primary cell surface protein called the M-protein. Over the past several decades, epidemiological studies have established associations between specific serotypes (M-types) and certain GAS infections like serotype M28 with puerperal sepsis, serotype M1 with the resurgence in severe invasive GAS infections observed since the mid-1980s, and serotype M3 with the lethal invasive infections. Nevertheless, the molecular mechanisms behind these associations are yet to be fully understood. Fundamental questions include: Does the presence or absence of certain genes in specific serotypes affect disease outcomes? Does serotype-specific gene expression play a role? This dissertation explores three main areas: i) The impact of the region of difference 2 (RD2), a genomic island, acquisition on the virulence of serotypes other than M28. ii) The potential role of the capsule as a barrier to RD2 acquisition in other serotypes. iii) The molecular basis for the low nra expression in M3 GAS serotype. The aforementioned areas are expected to shed new light on how serotypic gene expression and gene content lead to varying diseases/virulence outcomes.For the RD2 gain-of-function study, we show that the virulence-altering ability of RD2 is not restricted to M28 GAS isolates but also applies to isolates of other GAS serotypes. RD2, a mobile genetic element, is present in all M28 GAS isolates but absent in most of the other GAS serotypes. M28 GAS isolates are non-randomly associated with severe/lethal cases of puerperal sepsis. RD2 is of apparent group B Streptococcus (GBS) origin and is 36.3 kb long, encoding seven putative extracellular proteins that are possibly involved in establishing host-pathogen interactions, such as adhesion and colonization of the host. RD2 shares significant homology with two chromosomal regions of GBS. Notably, GBS isolates are associated with invasive neonatal infections and puerperal sepsis. Hence, we hypothesized that RD2 is the factor that non-randomly associates M28 GAS isolates with cases of puerperal sepsis. Previous studies have associated RD2 with enhanced adherence and colonization abilities in M28 GAS isolates, directly or indirectly, through encoded virulence factors or regulatory proteins. In this work, we have shown that RD2 enhances the adherence and colonization abilities of GAS isolates and the blood survival ability of isolates in a strain/serotype-specific manner. RD2 also influences the GAS transcriptome in a strain/serotype-specific manner, suggesting that this strain/serotype-specific virulence modulation by RD2 may determine GAS isolates' ability to establish infection in the host. Hence, this could be why RD2 is not ubiquitous in GAS serotypes. For RD2 and the barrier to its acquisition study, we study capsule as a factor that may be a potential barrier to the acquisition of RD2 by other GAS serotypes in nature. Our research shows that the presence and absence of the capsule do not affect the intra- or inter-serotype conjugation frequency. On investigating the role of capsule on RD2-mediated phenotypes using derivatives of M1 and M28 strains, we observed that while the presence of capsule does influence the RD2-mediated adherence ability of GAS isolates, there is no significant difference in the colonization ability of strains with RD2 in the presence and absence of a capsule. However, RD2-containing strains showed a significantly higher colonization ability than RD2-lacking strains. Therefore, our current study suggests that the capsule does not act as a barrier to RD2 acquisition, at least in the case of M1 isolates. For M3s, our work uncovers the molecular basis of a lower abundance of Nra, a positive regulator of pilus expression in the M3 GAS serotype, compared to the M1 GAS serotype. Pili are hair-like structures on bacterial cell surfaces that help organisms adhere, colonize, and establish host infection. The CovR/S system is a two-component regulatory system that negatively regulates virulence gene expression. CovS is a sensor kinase, and CovR is the response regulator, jointly regulating the transcription of approximately 10% of GAS genes. Our previous studies showed that nra gene expression and pili production are lower in M3s compared to M49s and M1s (Note that M1 has RofA, and not Nra, as a positive regulator of pilus gene expression). In this work, we conclude that the lower nra expression and pili abundance in M3s are a cumulative result of a point mutation in the nra gene and the repression of pilus gene expression by the CovR/S system. In addition, we also show that RofA and Nra are not interchangeable in function. Therefore, our study shows that the repression of pilus genes by CovR/S and expression of these genes occur in a strain- or type-specific manner. In summary, our work provides insight into strain- and serotype-specific variation in regulating virulence genes, particularly those related to adherence, colonization, and infection establishment in group A Streptococcus. This research contributes to developing prophylactic measures for puerperal sepsis and enhances our understanding of the variation in pilus expression, a potential vaccine candidate, across GAS serotypes
Comparative Life Cycle Assessment (LCA) of Different Asphalt Emulsion Types
Get PDFThe construction and maintenance of road infrastructure plays a vital role in modern society, with asphalt being a predominant material used for pavement construction. Asphalt emulsions are commonly used in several pavement applications. They are effective for preventive and corrective maintenance on asphalt or concrete pavements, base stabilization, new and rehabilitated pavement construction, and the recycling of end-of-life pavements. As environmental concerns increase and sustainability gains prominence, it becomes essential to evaluate the environmental impacts of various road construction materials and techniques. The principles of sustainability strive to integrate essential environmental, social, and economic elements into the process of decision-making. Life Cycle Assessment (LCA) is a methodology that quantifies the environmental impacts throughout the complete life cycle of a product or system, encompassing impacts that manifest at various stages within the supply chain. The primary objective of this research is to develop comprehensive framework, models, and databases for various types of asphalt emulsions at the production facilities. This effort is designed to quantify the environmental impacts of different asphalt emulsions, facilitating data-driven and integrated decision-making processes. The study's system boundary extends from cradle to gate, with the declared unit being 1 metric ton of asphalt emulsion. The study relies on up-to-date and illustrative data, including raw materials, asphalt emulsion formulations, energy sources, plant properties, and transportation information. Notably, the study specifically targets cationic asphalt emulsions. The following most utilized asphalt emulsions were selected after reviewing the specifications for all 50 State Departments of Transportation (DOTs): CSS 1, CSS-1H, CRS-2, and CRS-2P. Data collection was sourced from the comprehensive investigation of 17 asphalt emulsion production facilities across the United States (US).This study was organized in three phases: 1. Developing a life cycle inventory (LCI) database for asphalt emulsions. 2. Developing an appropriate LCA model for asphalt emulsion production. 3. Conducting a thorough life cycle impact assessment (LCIA) for various asphalt emulsion types, followed by a comparative analysis. Through these phases, an up-to-date LCI database was developed for asphalt emulsions to quantify their environmental impacts and for proper LCA modeling. Data collection involved literature reviews, asphalt emulsion supplier’s data, and the updated 2023 GaBi database. The LCIA analysis was conducted using GaBi software (version 10.7.1). Finally, a comparative analysis was conducted for the four evaluated asphalt emulsions, and a sensitivity analysis was performed to identify influential factors affecting their environmental impact. The results indicated that, overall, rapid-setting cationic emulsions (CRS-2 and CRS-2P) are more environmentally friendly. Additionally, the environmental impacts of CSS-1 and CSS-1H were found to be relatively close. Asphalt emulsions are respectively ranked from the lowest to the highest environmental impacts as CRS-2, CRS-2P, CSS-1H, and CSS-1H. The sensitivity analysis revealed that the hotspots for environmental impacts in asphalt emulsion production are, ranked from highest to lowest: the quantities of emulsifier, latex, and asphalt binder. In other words, the emulsifier exhibits the highest percentage change in global warming potential (GWP) per kilogram among the components of asphalt emulsion, followed by latex and asphalt binder
Working Memory in Those With a History of Concussion
Get PDFMild traumatic brain injury (mTBI), a common head injury, is expected to heal within weeks. However, deficits in visual working memory (WM) persist in undergraduates who report a history of mTBI (hmTBI). This pattern is observed years after injury. MTBI is a heterogenous group in several areas including etiology, treatment, age at injury, sex, and even WM performance. In other words, not all people with hmTBI are impaired in VWM, but a subset are. We proposed several related research questions: 1) are persistent WM deficits attributable to distributions of frontal lobe function, 2) is there a common neural signature associated with VWM impairment in hmTBI, and 3) can neuromodulation improve WM function in hmTBI? This dissertation addresses each of these related questions. Aim 1 extended our previous WM findings using a new task relying heavily on frontal lobe regions. We predicted greater deficits on this task compared to our previous WM tasks. Aim 2 investigated whether the subgroup showing WM deficits share an underlying neural signature. Electroencephalogram (EEG) data was used to train a classifier to determine whether a neural signature accurately predicts group membership (control, hmTBI low WM, hmTBI high WM). In Aim 3, we applied transcranial direct current stimulation (tDCS) with the goal of improving WM. The overall goal was to identify who has lasting traces of hmTBI, why they persist, and how to remediate VWM in those with residual deficits. Our results found no behavioral or neuronal difference between mTBI and controls. There was no group effect regardless of neuromodulation, task demands, or cognitive load. EEG data was unable to discriminate between hmTBI and controls. However, we did find a significant difference in VWM performance between the dataset collected for this dissertation and a dataset collected pre-COVID. The hmTBI population present at the University of Nevada, Reno may have changed after the pandemic. Our other major finding was in Aim 1. Performance was significantly higher on ACTS-WM than ACTS despite the increase cognitive load. This finding suggests abstract concepts, such as instructions, and concrete stimuli may be held in WM in separate stores. While our findings were mostly unexpected, they have interesting implications for WM theory and research in special populations
Extending Vision With Extended Reality
No full textExtended Reality (XR) head-mounted displays (HMD) are equipped with a camera system and a dichoptic display system. The sensory data captured by the camera system is not an accurate representation of the reality. Furthermore, the video-pass through to the HMD has compromised fidelity. In this body of work we describe the observer's vision by (a) quantifying their visual function into camera parameters in the Visual Function Testing framework and (b) simulating their functional visual capability on normal subjects by using those camera parameters on a virtual camera in the Functional Vision Testing framework. A direct by-product of such an approach is an XR countermeasure that can compensate perceptual loss brought on by these impairments by performing inverse mathematical operations on the camera input (c) in the Vision Rehabilitation Testing framework. This research tests and identifies improvements in XR systems in terms of rendering latency, simulation accuracy, objective modeling and display calibration to expand the functional capabilities of people with perceptual loss