Evolution of strength and physical properties of ultramafic and carbonate rocks under hydrothermal conditions

Interaction of rocks with fluids can significantly change mineral assemblage and structure. This so-called hydrothermal alteration is ubiquitous in the Earth’s crust. Though the behavior of hydrothermally altered rocks can have planet-scale consequences, such as facilitating oceanic spreading along slow ridge segments and recycling volatiles into the mantle at subduction zones, the mechanisms involved in the hydrothermal alteration are often microscopic. Fluid-rock interactions take place where the fluid and rock meet. Fluid distribution, flux rate and reactive surface area control the efficiency and extent of hydrothermal alteration. Fluid-rock interactions, such as dissolution, precipitation and fluid mediated fracture and frictional sliding lead to changes in porosity and pore structure that feed back into the hydraulic and mechanical behavior of the bulk rock. Examining the nature of this highly coupled system involves coordinating observations of the mineralogy and structure of naturally altered rocks and laboratory investigation of the fine scale mechanisms of transformation under controlled conditions. In this study, I focus on fluid-rock interactions involving two common lithologies, carbonates and ultramafics, in order to elucidate the coupling between mechanical, hydraulic and chemical processes in these rocks. I perform constant strain-rate triaxial deformation and constant-stress creep tests on several suites of samples while monitoring the evolution of sample strain, permeability and physical properties. Subsequent microstructures are analyzed using optical and scanning electron microscopy. This work yields laboratory-based constraints on the extent and mechanisms of water weakening in carbonates and carbonation reactions in ultramafic rocks. I find that inundation with pore fluid thereby reducing permeability. This effect is sensitive to pore fluid saturation with respect to calcium carbonate. Fluid inundation weakens dunites as well. The addition of carbon dioxide to pore fluid enhances compaction and partial recovery of strength compared to pure water samples. Enhanced compaction in CO2-rich fluid samples is not accompanied by enhanced permeability reduction. Analysis of sample microstructures indicates that precipitation of carbonates along fracture surfaces is responsible for the partial restrengthening and channelized dissolution of olivine is responsible for permeability maintenance.

Changes in the community structure of urban and rural forest patches in Baltimore from 1998 to 2015

Urban forests are often highly fragmented with many exotic species. Altered disturbance regimes and environmental pollutants influence urban forest vegetation. One of the best ways to understand the impacts of land-use on forest composition is through long-term research. In 1998, the Baltimore Ecosystem Study established eight forest plots to investigate the impacts of urbanization on natural ecosystems. Four plots were located in urban forest patches and four were located in rural forests. In 2015, I revisited these plots to measure abundances and quantify change in forest composition, diversity, and structure. Sapling, shrub, and seedling abundance were reduced in the rural plots. Alpha diversity and turnover was lower in the rural plots. Beta diversity was reduced in the rural plots. The structure of the urban plots was mostly unchanged, except for a highly reduced sapling layer. Beta diversity in the urban plots was consistent across surveys due to high species turnover.

THERE GOES THE ELECTORAL NEIGHBORHOOD: LOCAL NETWORKS, ATTRIBUTION OF RESPONSIBILITY, AND THE (UN) FAIRNESS OF ELECTIONS

During the last two decades there have been but a handful of recorded cases of electoral fraud in Latin America. However, survey research consistently shows that often citizens do not trust the integrity of the electoral process. This dissertation addresses the puzzle by explaining the mismatch between how elections are conducted and how the process is perceived. My theoretical contribution provides a double-folded argument. First, voters’ trust in their community members (“the local experience”) impacts their level of confidence in the electoral process. Since voters often find their peers working at polling stations, negative opinions about them translate into negative opinions about the election. Second, perceptions of unfairness of the system (“the global effect”) negatively impact the way people perceive the transparency of the electoral process. When the political system fails to account for social injustice, citizens lose faith in the mechanism designed to elect representatives -and ultimately a set of policies. The fact that certain groups are systematically disregarded by the system triggers the notion that the electoral process is flawed. This is motivated by either egotropic or sociotropic considerations. To test these hypotheses, I employ a survey conducted in Costa Rica, El Salvador, Honduras, and Guatemala during May/June 2014, which includes a population-based experiment. I show that Voters who trust their peers consistently have higher confidence in the electoral process. Whereas respondents who were primed about social unfairness (treatment) expressed less confidence in the quality of the election. Finally, I find that the local experience is predominant over the global effect. The treatment has a statistically significant effect only for respondents who trust their community. Attribution of responsibility for voters who are skeptics of their peers is clear and simple, leaving no room for a more diffuse mechanism, the unfairness of the political system. Finally, now I extend analysis to the Latin America region. Using data from LAPOP that comprises four waves of surveys in 22 countries, I confirm the influence of the “local experience” and the “global effect” as determinants of the level of confidence in the electoral process.

DEVELOPMENT OF LI+ AND NA+ CONDUCTING CERAMICS AND CERAMIC STRUCTURES FOR USE IN SOLID STATE BATTERIES

A solid state lithium metal battery based on a lithium garnet material was developed, constructed and tested. Specifically, a porous-dense-porous trilayer structure was fabricated by tape casting, a roll-to-roll technique conducive to high volume manufacturing. The high density and thin center layer (< 20 μm) effectively blocks dendrites even over hundreds of cycles. The microstructured porous layers, serving as electrode supports, are demonstrated to increase the interfacial surface area available to the electrodes and increase cathode loading. Reproducibility of flat, well sintered ceramics was achieved with consistent powderbed lattice parameter and ball milling of powderbed. Together, the resistance of the LLCZN trilayer was measured at an average of 7.6 ohm-cm2 in a symmetric lithium cell, significantly lower than any other reported literature results. Building on these results, a full cell with a lithium metal anode, LLCZN trilayer electrolyte, and LiCoO2 cathode was cycled 100 cycles without decay and an average ASR of 117 ohm-cm2. After cycling, the cell was held at open circuit for 24 hours without any voltage fade, demonstrating the absence of a dendrite or short-circuit of any type. Cost calculations guided the optimization of a trilayer structure predicted that resulting cells will be highly competitive in the marketplace as intrinsically safe lithium batteries with energy densities greater than 300 Wh/kg and 1000 Wh/L for under $100/kWh. Also in the pursuit of solid state batteries, an improved Na+ superionic conductor (NASICON) composition, Na3Zr2Si2PO12, was developed with a conductivity of 1.9x10-3 S/cm. New super-lithiated lithium garnet compositions, Li7.06La3Zr1.94Y0.06O12 and Li7.16La3Zr1.84Y0.16O12, were developed and studied revealing insights about the mechanisms of conductivity in lithium garnets.

Pathways to adulthood and their precursors: Roles of gender and race

Research on the transition to adulthood dates back nearly four decades, but a growing body of research has taken a new approach by investigating multiple demographic markers in the transition to adulthood simultaneously. Using the life course perspective, this dissertation is built on the literature by first examining contemporary young adults’ pathways to adulthood from ages 18 to 30 and their differences by gender. Data for this study were drawn from the National Longitudinal Survey of Youth 1997; the final sample included 2,185 men and 2,086 women. The college-educated single workers pathway, the college-educated married working parents pathway, and the high-school-educated single parents pathway were identified in both genders. For men, the study also identified the high-school-educated single workers pathway and the high-school-educated married working parents pathway. For women, the study also identified the high-school-educated workers pathway and the high-school-educated married parents pathway. Not only did the definitions of some pathways differ by gender, but even in the pathways with the same definition, gender differences were found in the probabilities of being married, of being a parent, or of being employed full-time. Based on the pathways to adulthood identified, this research examined the family and adolescent precursors and whether race moderates the associations between family structure experiences and young adults’ pathways to adulthood. Parental education, family structure, GPA, delinquency, early sexual activity, and race/ethnicity were the family and adolescent precursors that distinguished among pathways taken by the youth. Two interactions between race and family structure/instability were identified. The positive association between growing up in a single-parent family and the odds of taking the high-school-educated single workers pathway compared to the college-educated married working parents pathway was weaker for Black males than for White males. The positive association between family instability and the odds of taking the college-educated single workers pathway compared to the college-educated married working parents pathway was weaker for Black females than for White females. This dissertation accounted for changes in the multiple statuses related to becoming an adult by following contemporary young adults for 12 years. More research on contemporary young adults’ pathways to adulthood and subgroup differences in the effects of precursors are recommended. Limitations and implications of this study are discussed.

Influence of Acute and Chronic Exercise on Markers of Hippocampal Plasticity

Exercise and physical activity are lifestyle behaviors associated with enriched mental health. Understanding the mechanisms by which exercise and physical activity improve mental health may provide insight for novel therapeutic approaches for numerous mental health disorders. This dissertation reports the findings from three studies investigating the influence of acute and chronic exercise on behavioral and mechanistic markers of hippocampal plasticity and delves into the potential role of noradrenergic signaling in the hippocampal adaptations with exercise. The first study assessed the effects of long-term voluntary wheel running on hippocampal expression of plasticity-associated genes and proteins in adult male and female C57BL/6J mice, highlighting sex differences in the adaptations to long-term voluntary wheel running. The second study examined the influence of acute exercise intensity on AMPA receptor phosphorylation, a mechanism essential for hippocampal plasticity, plasticity- associated gene expression, spatial learning and memory, and anxiety-like behavior. The unexpected finding that acute exercise increased anxiety-like behavior encouraged investigation into the role of central noradrenergic signaling in acute exercise-induced anxiety. The third study determined how previous exposure to voluntary wheel running modulates the response to an acute bout of exercise, focusing primarily on transcription of the important plasticity-promoting gene, brain-derived neurotrophic factor. Using a pharmacological approach to compromise the locus coeruleus noradrenergic system, a system that is implicated in age-related mental health disorders such as Alzheimer’s Disease, the third study also investigated the influence and interaction of the noradrenergic system and acute exercise on expression of multiple brain-derived neurotrophic factor transcripts. Together, this dissertation reports the findings from a series of experiments that explored similarities, differences, and interactions between the effects of acute and chronic exercise on markers of hippocampal plasticity and behavior. Further, this work provides insight into the role of the noradrenergic system in exercise-induced hippocampal plasticity.

Shared Insights: A Survey of Postsecondary and Adult Men's Chorus Directors

The following dissertation focuses on the all-male chorus context. Through a survey of university, GALA and adult affiliated community chorus directors on the specific challenges – vocal pedagogy, rehearsal techniques, auditioning, and repertoire – of the TTBB chorus, valuable insights were gathered from participating directors that serve to supplement existing literature available to directors.

Comparison of Hydrologic and Hydraulic Characteristics of the Anacostia River to Non-Urban Coastal Streams

Streams in urban areas often utilize channelization and other bank erosion control measures to improve flood conveyance, reduce channel migration, and overbank flooding. This leads to reductions in evapotranspiration and sediment storage on floodplains. The purpose of this study is to quantify the evapotranspiration and sediment transport capacity in the Anacostia Watershed, a large Coastal Plain urban watershed, and to compare these processes to a similar sized non-urban watershed. Times series data of hydrologic and hydraulic changes in the Anacostia, as urbanization progressed between 1939-2014, were also analyzed. The data indicates lower values of warm season runoff in the non-urban stream, suggesting a shift from evapotranspiration to runoff in urban streams. Channelization in the Anacostia also increased flow velocities and decreased high flow width. The high velocities associated with channelization and the removal of floodplain storage sites allows for the continued downstream transport of sediment despite stream bank stabilization.

THE ROLE OF RULES, EXAMPLES AND INDIVIDUAL DIFFERENCES IN THE ACQUISITION OF DECLARATIVE AND PROCEDURAL SECOND LANGUAGE KNOWLEDGE

The relevance of explicit instruction has been well documented in SLA research. Despite numerous positive findings, however, the issue continues to engage scholars worldwide. One issue that was largely neglected in previous empirical studies - and one that may be crucial for the effectiveness of explicit instruction - is the timing and integration of rules and practice. The present study investigated the extent to which grammar explanation (GE) before practice, grammar explanation during practice, and individual differences impact the acquisition of L2 declarative and procedural knowledge of two grammatical structures in Spanish. In this experiment, 128 English-speaking learners of Spanish were randomly assigned to four experimental treatments and completed comprehension-based task-essential practice for interpreting object-verb (OV) and ser/estar (SER) sentences in Spanish. Results confirmed the predicted importance of timing of GE: participants who received GE during practice were more likely to develop and retain their knowledge successfully. Results further revealed that the various combinations of rules and practice posed differential task demands on the learners and consequently drew on language aptitude and WM to a different extent. Since these correlations between individual differences and learning outcomes were the least observed in the conditions that received GE during practice, we argue that the suitable integration of rules and practice ameliorated task demands, reducing the burden on the learner, and accordingly mitigated the role of participants’ individual differences. Finally, some evidence also showed that the comprehension practice that participants received for the two structures was not sufficient for the formation of solid productive knowledge, but was more effective for the OV than for the SER construction.

Cortisol Awakening Response in Preschoolers and Depression Risk: Relations with Maternal History of Depression and Child Temperament

Increasing research suggests that elevations in the cortisol awakening response (CAR), the natural increase of cortisol 30 to 40 minutes after waking, may serve as a vulnerability marker for depression. However, existing studies have focused on adolescence and adulthood; very little is known about the CAR in early childhood and the factors that are associated with it. The current study aimed to examine the validity of the CAR as a potential early-emerging vulnerability marker for depression in a sample of preschool-age children. We examined associations between the CAR and two well-established risk factors for depression: maternal psychopathology and early child temperament (high negative emotionality (NE) and/or low positive emotionality (PE)). The sample consisted of 146 preschool-age children, of whom 71 (49.3%) had a biological mother with a history of depression and 65 (45.5%) had a biological mother with a history of anxiety. To assess the CAR, salivary cortisol samples were collected from the child upon waking, 30 and 45 minutes post-waking on two weekdays. Children’s CAR was examined as the total volume of cortisol secreted (AUCg) and the total increase in cortisol (AUCi) across waking. Evening cortisol was collected 30 minutes before bedtime. Child temperament was assessed using observational laboratory measures. Maternal depression and anxiety were assessed with clinical interviews. Associations with children’s CAR, as indicated by AUCg or AUCi, appeared to be specific to maternal current psychopathology and symptoms of anhedonia. Additionally, we observed significant interactions for both maternal lifetime and current depression and anxiety, in combination with child NE and PE, on elevated evening cortisol levels and flattened diurnal cortisol rhythms, indicating altered patterns of basal cortisol activity in offspring. Our study contributes to the limited but growing knowledge on the development of the CAR in preschool age children and as a marker of early risk. Findings suggest that there is a complex interplay between familial risk, affective vulnerability, and their joint effects on neuroendocrine dysfunction in young children, and highlight the need for future research to examine which aspects of the early diurnal rhythm predict the emergence of later depressive illness.

Development of Planning And Evaluation Models For Superstreets

Despite the extensive implementation of Superstreets on congested arterials, reliable methodologies for such designs remain unavailable. The purpose of this research is to fill the information gap by offering reliable tools to assist traffic professionals in the design of Superstreets with and without signal control. The entire tool developed in this thesis consists of three models. The first model is used to determine the minimum U-turn offset length for an Un-signalized Superstreet, given the arterial headway distribution of the traffic flows and the distribution of critical gaps among drivers. The second model is designed to estimate the queue size and its variation on each critical link in a signalized Superstreet, based on the given signal plan and the range of observed volumes. Recognizing that the operational performance of a Superstreet cannot be achieved without an effective signal plan, the third model is developed to produce a signal optimization method that can generate progression offsets for heavy arterial flows moving into and out of such an intersection design.

Factors Analyses of Effecting to Milk Production and Economic Efficiency of Dairy Goat Agribisness In Kaligesing District of Purworejo Region

A survey in the agribusiness of dairy goat smallholder had been conducted in Kaligesing district of Purworejo region at 13 rd September up to 7th November 2001. The survey studied the factors effecting the milk yield, in how the factors influence economically. Forty eight respondents (dairy goat smallholders) were used in this study and interview method was applied for collecting data. The variables were observed; lactation goat, man power, garage, and concentrate ration. Cobb-Douglass method was applied for analyzing the data. To know the economic efficiency of the agribusiness was approached by the ratio between the Marginal Product Value an input cost. From the data analysis it could be in formatted that the numbers of lactating goat and the numbers of lactating goat and the numbers of concentrate were significant influence on the milk yield, white the man power and the forage were not significant influence. For the numbers of lactating goat and concentrate, economically the efficiency was not yet reached, so the use of the factors were ought to be increased up to an appoint limited. On the other hand the man power and forage was not efficient, so the use of the factors need to be descreased. (Animal Production 4(1): 27-31 (2002)Key word : Production factors, economics efficiency, dairy goat PE

Non-motorized public transport : a global review and analysis of trends and issues

Over recent decades there has been growing interest in the role of non-motorized modes in the overall transport system (especially walking and cycling for private purposes) and many government initiatives have been taken to encourage these active modes. However there has been relatively little research attention given to the paid form of non-motorized travel which can be called non-motorized public transport (NMPT). This involves cycle-powered vehicles which can carry several passengers (plus the driver) and a small amount of goods; and which provide flexible hail-and-ride services. Effectively they are non-motorized taxis. Common forms include cycle-rickshaw (Bangladesh, India), becak (Indonesia), cyclos (Vietnam, Cambodia), bicitaxi (Columbia, Cuba), velo-taxi (Germany, Netherland), and pedicabs (UK, Japan, USA). --------- The popularity of NMPT is widespread in developing countries, where it caters for a wide range of mobility needs. For instance in Dhaka, Bangladesh, rickshaws are the preferred mode for non-walk trips and have a higher mode share than cars or buses. Factors that underlie the continued existence and popularity of NMPT in many developing countries include positive contribution to social equity, micro-macro economic significance, employment creation, and suitability for narrow and crowded streets. Although top speeds are lower than motorized modes, NMPT is competitive and cost-effective for short distance door-to-door trips that make up the bulk of travel in many developing cities. In addition, NMPT is often the preferred mode for vulnerable groups such as females, children and elderly people. NMPT is more prominent in developing countries but its popularity and significance is also gradually increasing in several developed countries of Asia, Europe and parts of North America, where there is a trend for the NMPT usage pattern to broaden from tourism to public transport. This shift is due to a number of factors including the eco-sustainable nature of NMPT; its operating flexibility (such as in areas where motorized vehicle access is restricted or discouraged through pricing); and the dynamics that it adds to the urban fabric. Whereas NMPT may have been seen as a “dying” mode, in many cities it is maintaining or increasing its significance and with potential for further growth. --------- This paper will examine and analyze global trends in NMPT incorporating both developing and developed country contexts and issues such as usage patterns; NMPT policy and management practices; technological development; and operational integration of NMPT into the overall transport system. It will look at how NMPT policies, practices and usage have changed over time and the differing trends in developing and developed countries. In particular, it will use Dhaka, Bangladesh as a case study in recognition of its standing as the major NMPT city in the world. The aim is to highlight NMPT issues and trends and their significance for shaping future policy towards NMPT in developing and developed countries. The paper will be of interest to transport planners, traffic engineers, urban and regional planners, environmentalists, economists and policy makers.

An examination of the base rates of post-concussion symptoms : the influence of demographics and depression

Post-concussion syndrome (PCS) is a controversial constellation of cognitive, emotional, and physical symptoms that some patients experience following a mild traumatic brain injury or concussion. PCS-like symptoms are commonly found in individuals with depression, pain, and stress, as well as healthy individuals. This study investigated the base rate of PCS symptoms in a healthy sample of 96 participants and examined the relationship between these symptoms, depression, and sample demographics. PCS symptoms were assessed using the British-Columbia Post-Concussion Symptom Inventory. Depression was measured using the Beck Depression Inventory II. Results demonstrated that: The base rate of PCS was very high; there was a strong positive relationship between depression and PCS; and demographic characteristics were not related to PCS in this sample. These findings are broadly consistent with literature suggesting a significant role for non-neurological factors in the expression of PCS symptomatology. This study adds to the growing body of literature that calls for caution in the clinical interpretation of results from PCS symptom inventories.

Safety impacts of alcohol and other drugs in the construction industry : a research methodology

Anecdotal evidence from the infrastructure and building sectors highlights issues of drugs and alcohol and its association with safety risk on construction sites. Operating machinery and mobile equipment, proximity to live traffic together with congested sites, electrical equipment and operating at heights conspire to accentuate the potential adverse impact of drugs and alcohol in the workplace. While most Australian jurisdictions have identified this as a critical safety issue, information is limited regarding the prevalence of alcohol and other drugs in the workplace and there is limited evidential guidance regarding how to effectively and efficiently address such an issue. No known study has scientifically evaluated the relationship between the use of drugs and alcohol and safety impacts in construction, and there has been only limited adoption of nationally coordinated strategies, supported by employers and employees to render it socially unacceptable to arrive at a construction workplace with impaired judgement from drugs and alcohol. A nationally consistent collaborative approach across the construction workforce - involving employers and employees; clients; unions; contractors and sub-contractors is required to engender a cultural change in the construction workforce – in a similar manner to the on-going initiative in securing a cultural change to drink-driving in our society where peer intervention and support is encouraged. This study has four key objectives. Firstly, using the standard World Health Organisation AUDIT, a national qualitative and quantitative assessment of the use of drugs and alcohol will be carried out. This will build upon similar studies carried out in the Australian energy and mining sectors. Secondly, the development of an appropriate industry policy will adopt a non-punitive and rehabilitative approach developed in consultation with employers and employees across the infrastructure and building sectors, with the aim it be adopted nationally for adoption at the construction workplace. Thirdly, an industry-specific cultural change management program will be developed through a nationally collaborative approach to reducing the risk of impaired performance on construction sites and increasing workers’ commitment to drugs and alcohol safety. Finally, an implementation plan will be developed from data gathered from both managers and construction employees. Such an approach stands to benefit not only occupational health and safety, through a greater understanding of the safety impacts of alcohol and other drugs at work, but also alcohol and drug use as a wider community health issue. This paper will provide an overview of the background and significance of the study as well as outlining the proposed methodology that will be used to evaluate the safety impacts of alcohol and other drugs in the construction industry.