- ItemEffects of post hatch delayed-feeding stress on enteric nervous activity and intestinal nutrient transport in broiler chickens(University of Delaware, 2022) Schlitzkus, Lydia C.Early life stress alters gastrointestinal (GI) development leading to functional disorders (such as leaky gut, malnutrition, etc.). This leads to negative consequences later in life. The enteric nervous system (ENS) that coordinates many functions of the intestine is sensitive to stress and has been overlooked in agricultural animal’s health. Post-hatch delayed feeding in the broiler industry is a common stressor which impairs the intestinal development and health of birds. This project serves to evaluate the effects of post-hatch delayed feeding stress on enteric nervous activity, and intestinal nutrient transport in broiler chickens. Ross 308 birds were incubated, hatched, and immediately allotted into either a normal feeding (NF) or delayed feeding (DF) group. DF birds did not receive feed for 72 hours post-hatch, while NF birds had immediate access to feed. Both groups had ad libitum access to water throughout the entire trial and following the 72 hours, DF birds and NF birds had ad libitum access to the same commercial diet until day 42 of age. At day 42 of age, a subset of each group experienced a 24-hour period of feed restriction to serve as a secondary stress event. Growth performance parameters were collected weekly throughout the 6 week grow out period. At day 3, 14, and 42 birds were euthanized, and intestinal samples were taken. Intestinal function was evaluated using the Ussing Chambers. ☐ It was found that experiencing early life stress triggered immediate and long lasting changes in the intestinal functions and ENS activities of broiler chickens. Growth performance was reduced after the initial 72 hour feed delay, but by day 42 the DF birds are able to recover. The DF group had a lower FCR which suggests that there may be a mechanism such as increased nutrient absorption to allow for increased feed efficiency and potential compensatory growth. ☐ These changes can predispose the birds to a higher risk of later life GI infectious diseases, especially under suboptimal growth conditions with secondary stress. The stressed birds were more adaptive to a secondary stress in terms of less ENS neural mediated responses and enhanced nutrient transport functions. An enhanced electrogenic nutrient transport function in the stressed birds could be the mechanism for compensatory growth seen in this group. Understanding the link between ENS activities and intestinal functions in stressed animals could give insight into developing novel targets that lead to the improvement of GI health and animal production.
- ItemA suite of agronomic factors can offset the effects of climate variability on rainfed maize production in Kenya(University of Delaware, 2022) Oluoch, Kevin Ong'areAchieving food security in sub-Saharan Africa (SSA) is a multidimensional challenge. SSA reliance on food imports is expected to grow in the coming decades to meet the population's demand, projected to double to over 2 billion people by 2050. In addition, climate change is already affecting food production and supply chains across the region. Addressing these multiple food security challenges will necessitate rapid enhancements in agricultural productivity, which is influenced by a host of demographic, agronomic, and climatic factors. We use statistical approaches to examine rainfed maize in Kenya, where maize cultivation and consumption are widespread and central to livelihoods and national food security. We find that improving a suite of agronomic factors will have a greater effect on rainfed maize productivity than demographics and can offset the effects of climate change. These findings could also offer insights into similar challenges for other crops in Kenya and other SSA countries.
- ItemImpacts of urbanization and climate change over the 21st century on coastal wind resources in the Mid-Atlantic U.S.(University of Delaware, 2022) Frei, Brian P.Climate change and urbanization can alter coastal wind resources available for energy production by modifying pressure patterns, local thermodynamics, and land surface properties. The Mid-Atlantic U.S. has a burgeoning offshore wind industry, with strong potentials for drastic climate change and widespread urbanization. Here I investigate how climate change and urbanization over the 21st century collectively and respectively affect coastal winds, using the Mid-Atlantic U.S. as an example region. Urbanization causes increased summertime wind speeds over the ocean (0.4 – 0.6 m/s) and decreased wind speeds over land with minimal offshore impacts in other seasons. Similarly, climate change causes the largest impacts on wind resources in the summer, with offshore wind speed increases between 0.8 – 1.4 m/s. While urbanization strengthens the sea breeze circulation through enhanced land-ocean temperature gradients, climate change weakens it. Both climate change and urbanization cause substantial increases in extreme heat conditions in the Mid-Atlantic U.S. These findings suggest that the impacts of both urbanization and climate change are vital to consider as offshore wind energy develops along urbanizing coastal areas.
- ItemSecondary music teachers' self-efficacy in teaching songwriting(University of Delaware, 2022) Engel, Emma E.Songwriting has been used in the fields of music education and music therapy to encourage collaboration (Kennedy 2002; Jaffurs 2014; McGillen & McMillan, 2005), self-expression (Airy & Parr, 2010; Tobias 2012), and healing (Fairchild & McFerran, 2019; Lindberg 1995). As popular music and creativity in music become more widely included in music curricula in the United States, some teachers have also included songwriting in their classrooms (Draves, 2008; Jaffurs; 2014; Tobias, 2012). Though teachers may have positive attitudes towards songwriting, they may still exclude it from their curriculum (Brinkman, 1995; Roberts, 1995; Sloboda, 1985). ☐ Authors have suggested different approaches and practices for teaching songwriting and the benefits it may have if used in the music classroom (Draves, 2008; Jaffurs; 2014; Tobias, 2012). If music teachers are open to include popular musics, what might prevent them from using songwriting in their classroom? One possible reason teachers may not include songwriting is their perceived self-efficacy in teaching songwriting. Bandura’s (1994) theory of self-efficacy has been used to investigate students’ decisions and teachers’ pedagogical choices (Brudnick, 2009; Garvis, 2012; Landino & Owen, 1988; Menon & Sadler, 2016). While researchers have investigated the relationship between songwriting and self-efficacy (Lindberg, 1995; Randles, 2010; Richardson, 2011), the reason for teachers’ curricular choices regarding songwriting has yet to be discovered. Self-efficacy has been shown to affect choices, behavior, and motivation, and could attribute to teachers’ ability to include songwriting in their classrooms (Brudnick, 2009; Garvis, 2012; Landino & Owen, 1988; Menon & Sadler, 2016). ☐ Therefore, the purpose of this multiple case study was to investigate secondary music teachers’ self-efficacy in teaching songwriting. The research problems for this study were as follows: ☐ 1.To describe the music teachers’ prior experiences with songwriting and the teaching of songwriting to others. ☐ 2.To describe music teachers’ self-perceptions regarding their ability to teach songwriting. ☐ Sub-questions included (a) What materials and resources do the teachers use to facilitate songwriting in their classroom? (b) Do those resources contribute to their self-efficacy regarding teaching the course? (c) What resources do they feel would be most helpful to develop stronger self-efficacy for teaching songwriting to others? ☐ This multiple case study (Stake, 1995) utilized purposive sampling (Patten & Newhart, 2018) to examine two middle school music educators in the Northeastern region of the United States who teach creative music in some way (e.g., a lesson/unit, a stand-alone course). Data collection consisted of semi-structured interviews, teaching observations, and an examination of their relevant teaching documents. The findings of this study suggest that teachers’ self-efficacy in teaching songwriting may come from overall teaching experience and there are few applicable resources for teaching songwriting. Implications and suggestions for practice and further research for music educators are also discussed.
- ItemEffect of nitrogen source on the thermal tolerance of different strains of the symbiotic dinoflagellate Breviolum minutum in culture and within a cnidarian host(University of Delaware, 2022) Capista, JessicaSymbiotic cnidarians often occupy oligotrophic environments but are able to thrive due to their dinoflagellate symbionts, however, rising temperatures and changing nutrient regimes put this symbiosis at risk of bleaching. Bleaching response is highly dependent on nutrient concentration, nitrogen form, and stoichiometry, as moderate NO3- enrichments, especially in the absence of balanced phosphorus additions have been linked to increased bleaching while moderate NH4+ enrichments are associated with increased thermal tolerance. Despite these differential responses, the underlying mechanisms driving these outcomes are not well understood. Since algal photosystem II (PSII) is a central target of bleaching, I hypothesized the additional energy requirement of reducing NO3- to NH4+ in the chloroplast was driving electrons away from photosynthesis and slowing PSII protein repair rates, thus leading to increased damage. I investigated how NO3- and NH4+ in tandem with heating effected Breviolum minutum in culture and within the cnidarian host, Exaiptasia diaphana. Contrary to previous work on coral hosts, I did not find a clear differential response based on nitrogen form in culture or within a sea anemone host. Additionally, a bleaching response was observed as a loss of algal cells in culture and in hospite but PSII did not appear to be damaged. My findings highlight the importance of assessing multiple cnidarian hosts and closer examining how both the algae and the host respond to better predict how these organisms will respond to future climate conditions.