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Mechanisms of Perennial Sorghum Resistance to Sugarcane Aphid Infestation
Get PDFSorghum, Sorghum bicolor (L.) Moench, the fifth most-grown cereal crop in the world, is a versatile crop, grown across different agro-ecological regions. Sorghum has numerous uses ranging from food and forage purposes to biofuel production. Sugarcane aphid (SCA; Melanaphis sacchari) is a major threat to sorghum production, accounting for 50% to 100% yield loss under heavy infestations. Perennial sorghum can be a sustainable and climate-resilient alternative to the current cereal farming systems. The development of perennial sorghum offers numerous benefits, such as reduced economic inputs, more carbon sequestration, better soil health, and sustainable yields. We employed host plant resistance (HPR) to screen forty-three perennial sorghum genotypes for their response to SCA infestation, aiming to identify resistant and susceptible genotypes. The no-choice assay (antibiosis levels) results divided the genotypes into four clusters (highly susceptible, moderately susceptible, moderately resistant, and highly resistant), based on aphid count and plant damage. We selected two genotypes, X999\u3eR485 (SCA-resistant) and PR376~Tift241 (SCA-susceptible), and tested their antixenosis levels of resistance using choice assay and electrical penetration graph (EPG). The SCA-resistant genotype is highly resistant to SCA infestation, while the SCA-susceptible genotype has weak resistance. To better understand the factors modulating the resistance in these two genotypes, we used transcriptomics to identify the molecular and genetic mechanisms underlying perennial sorghum’s response to SCA infestation. Transcriptional response of perennial sorghum to SCA feeding at early and late time points showed that aphid feeding induces plant defenses by regulating the expression of genes related to reactive oxygen species (ROS) production, death acids, cell wall-related modifications, and callose synthesis in the SCA-resistant perennial sorghum genotype. Overall, transcriptomic results indicate that the SCA-resistant perennial sorghum genotype rapidly triggered plant defenses against SCA infestation. The identification of SCA-resistant perennial sorghum genotypes and the specific pathways and genetic mechanisms dominating this interaction will guide future perennial sorghum breeding programs.
Advisor: Joe Loui
Radar Precursors to Severe Weather Reports in Left-moving Supercells
Get PDFWhile much research has examined dual-polarimetric signatures of right-moving supercells, very little has been done with left-moving supercells. Given that left-moving supercells are thought to be disproportionate producers of large hail, understanding their internal dynamics is vitally important. This study examines differences and trends in the dual-polarimetric signatures of left-moving supercells to identify precursors to severe weather reports. A dataset of left-moving supercells associated with severe weather reports was created. These storms are processed with an automated analysis algorithm that identifies and quantifies the polarimetric signatures in each storm. A method for analysis of differences and trends in their dual-polarization signatures in the 30 minutes prior to a severe weather report is developed. ZDR columns and arcs are used to infer changes in storm and updraft strength. ZDR arcs show no statistically significant differences leading to a severe hail report. The increase in reflectivity magnitude over the 30-minute analysis period prior to a severe hail report is statistically significant. The key finding from this research is that ZDR columns show a statistically significant decreasing trend in both depth and areal extent leading to a severe hail report, which may be operationally valuable.
Advisor: Matthew S. Van Den Broek
Culture and Context: How Frames of Teaching and of Learning Mathematics Form and Change for Graduate Student Instructors
Get PDFWhy do instructors teach the way that they do? This question is key in understanding how and why asset-based or deficit-based practices are enacted in the classroom. In consequence, this question also gives insight into how the environment where students learn is shaped. Mathematics education research, in particular, has been concerned with how instructors respond to students’ contributions in the classroom and how these ways of responding can (dis)empower students.
One way to answer this question is to understand how instructors frame their own teaching and their students’ learning. Frames are mental constructs which help individuals filter details, interpret information, and decide how to appropriately proceed. While research has affirmed the utility of frames in understanding instructors’ actions, the concept of frames has yet to be examined in the specific context of teaching and learning mathematics. This dissertation argues that more can be understood about why mathematics instructors teach the way they do when frames of teaching and of student learning are explored deeply.
Using a mix of grounded theory and narrative analysis, I investigated the experiences of three mathematics graduate student instructors and their frames of teaching and of student learning during their first semester of teaching as the main instructor. Salient aspects of frames of teaching and of learning mathematics surfaced in the interviews, classroom observations, and written reflections. I produced a novel analytic framework for mathematics instructors’ frames of teaching and of students’ learning. Then, using this framework, I reconstructed narratives of these instructors’ frames and how they began, changed, crystallized, or strengthened as the semester progressed. Lastly, aspects of culture which shape instructors’ frames of teaching and of student learning were extracted from these narratives, interviews, observations, and reflections. Thus, this dissertation gives one answer to the opening question.
These narratives and insights have implications for the professional development of future mathematics instructors, including how instructors might be better oriented to manage classroom events. By detailing how frames may change and naming the aspects of culture which shape frames, instructors better understand how to adopt asset-based frames and practices which can empower students in mathematics courses.
Advisor: Yvonne La
Advancing Butterfly Systematics through Genomic Analysis
Get PDFWithin the framework of an ongoing comparative genomic study of global butterfly diversity, we construct phylogenetic trees combining all protein-coding genes assembled from the whole genome shotgun data. When viewed in the context of current taxonomy and phenotypic knowledge, the genome-wide phylogeny points to further advances in butterfly systematics, which are presented here. We assign major clades with comparable levels of genetic divergence to the same taxonomic rank and apply criteria involving relative population divergence and gene flow to define species boundaries. As a result, one genus, 13 subgenera, 62 species, and five subspecies are proposed as new (type species in original combinations or type localities are given in parentheses): a genus Ajenorix Grishin, gen. n. (Rapala hypargyria Elwes, 1893) in Deudorigini Doherty, 1886, Lycaenidae [Leach], [1815]; subgenera: in Riodinidae Grote, 1895 (1827): Ouida Grishin, subgen. n. (Dodona ouida Hewitson, 1866) and Egeona Grishin, subgen. n. (Taxila egeon Westwood, 1851) of Dodona Hewitson, 1861, Locris Grishin, subgen. n. (Lasaia oileus Godman, 1903) of Lasaia H. Bates, 1868, Lucispila Grishin, subgen. n. (Hesperia lucianus Fabricius, 1793) of Parvospila J. Hall, 2018, Byzia Grishin, subgen. n. (Lemonias byzeres Hewitson, 1872) of Zelotaea H. Bates, 1868, Arichlosyne Grishin, subgen. n. (Apodemia ochracea Mengel, 1902) of Aricoris Westwood, 1851, and Lenca Grishin, subgen. n. (Lemonias lencates Hewitson, 1875) of Pachythone H. Bates, 1868; in Lycaenidae: Afrix Grishin, subgen. n. (Dipsas antalus Hopffer, 1855) of Capys Hewitson, 1865, Wacus Grishin, subgen. n. (Myrina epirus C. Felder, 1860) of Deudorix Hewitson, 1863, and Crates Grishin, subgen. n. (Hesperia isocrates Fabricius, 1793) of Virachola F. Moore, 1881; and in Hesperiidae Latreille, 1809: Ochloba Grishin, subgen. n. (Poanes batesi Bell, 1935), Ochlata Grishin, subgen. n. (Hesperia venata Bremer & Grey, 1853), and Ochluma Grishin, subgen. n. (Hesperia yuma W. H. Edwards, 1873) of Ochlodes Scudder, 1872; species: in Riodinidae: Lasaia cola Grishin, sp. n. (Mexico: Colima), Curvie wing Grishin, sp. n. (USA: Texas), Curvie westwing Grishin, sp. n. (Mexico: Sonora), Curvie chiapensis Grishin, sp. n. (Mexico: Chiapas), Emesis (Tenedia) tinia Grishin, sp. n. (Argentina), Emesis (Tenedia) guaya Grishin, sp. n. (Uruguay), Emesis (Aphacitis) bugaba Grishin, sp. n. (Panama: Chiriquí), and Synargis rectanga Grishin, sp. n. (Peru: San Martin) and in Hesperiidae: Phanus ecutinus Grishin, sp. n. (Ecuador: Pichincha), Entheus zeus Grishin, sp. n. (Brazil: Amazonas), Entheus guyaneus Grishin, sp. n. (Guyana), Entheus colombeus Grishin, sp. n. (eastern Colombia), Entheus proxemus Grishin, sp. n. (Brazil: Pará), Entheus peruveus Grishin, sp. n. (Peru: Madre de Dios), Entheus hyponota Grishin, sp. n. (Brazil: Amazonas), Entheus lina Grishin, sp. n. (Brazil: Pará), Entheus guato Grishin, sp. n. (Mexico: Chiapas), Entheus pano Grishin, sp. n. (Panama: Darién), Entheus venezuelius Grishin, sp. n. (Venezuela: Aragua), Entheus ecuadius Grishin, sp. n. (Ecuador: Napo), Entheus bogoteus Grishin, sp. n. (Colombia: Bogotá), Cecropterus (Thorybes) notochlorothrix Grishin, sp. n. (Brazil: Santa Catarina), Urbanus (Urbanoides) elma Grishin, sp. n. (Venezuela: Merida), Telegonus (Rhabdoides) missionus Grishin, sp. n. (USA: Texas), Telegonus (Rhabdoides) panavenus Grishin, sp. n. (Panama: Panamá), Telegonus (Rhabdoides) pacificus Grishin, sp. n. (Peru: Piura), Telegonus (Rhabdoides) amazonicus Grishin, sp. n. (Brazil: Rondônia), Telegonus (Rhabdoides) pallidus Grishin, sp. n. (Panama: Darién), Telegonus (Rhabdoides) subfuscus Grishin, sp. n. (Brazil: Santa Catarina), Telegonus (Rhabdoides) elorianus Grishin, sp. n. (likely Southeast or South Brazil), Telegonus (Rhabdoides) perumazon Grishin, sp. n. (Peru: Madre de Dios), Telegonus (Rhabdoides) steinhauseri Grishin, sp. n. (Mexico: Veracruz), Telegonus (Rhabdoides) chiapus Grishin, sp. n. (Mexico: Chiapas), Telegonus (Rhabdoides) colotrix Grishin, sp. n. (Colombia: Cauca), Telegonus (Rhabdoides) flavimargo Grishin, sp. n. (Costa Rica: Limón), Telegonus (Rhabdoides) sobrasus Grishin, sp. n. (Brazil: Santa Catarina), Telegonus (Rhabdoides) chuchuvianus Grishin, sp. n. (Ecuador: Esmeraldas), Telegonus (Rhabdoides) panamus Grishin, sp. n. (Panama: Panamá Oeste), Telegonus (Rhabdoides) tatus Grishin, sp. n. (Panama: Panamá), Telegonus (Rhabdoides) fulvimargo Grishin, sp. n. (Peru: Cuzco), Telegonus (Rhabdoides) alardinus Grishin, sp. n. (Brazil: Rio de Janeiro), Pellicia (Hemipteris) cina Grishin, sp. n. (Brazil: Rondônia), Gorgopas trochicuz Grishin, sp. n. (Peru: Cuzco), Gorgopas trocha Grishin, sp. n. (Colombia: Tolima), Gorgopas trochitango Grishin, sp. n. (Argentina: Salta), Perus (Perus) perus Grishin, sp. 1 n. (Peru: Amazonas), Gomalia westafra Grishin, sp. n. (Ghana: Oti), Chirgus (Chirgus) argentinus Grishin, sp. n. (Argentina: Jujuy), Chirgus (Chirgus) teres Grishin, sp. n. (Peru: Junín), Chirgus (Chirgus) sombrus Grishin, sp. n. (Peru: Puno), Zopyrion (Zopyrion) xerxes Grishin, sp. n. (Honduras: San Pedro Sula), Anisochoria bacchoides Grishin, sp. n. (El Salvador: La Libertad), Onespa nuba Grishin, sp. n. (Mexico: Oaxaca), Vacerra tama Grishin, sp. n. (Mexico: Tamaulipas), Vacerra saltina Grishin, sp. n. (Argentina: Salta), Vacerra cuza Grishin, sp. n. (Peru: Cuzco), Oligoria (Oligoria) tinalandia Grishin, sp. n. (Ecuador: Santo Domingo de los Tsáchilas), Eutychide trombella Grishin, sp. n. (Costa Rica: Heredia), Talides hispina Grishin, sp. n. (Ecuador: Napo), Damas honduras Grishin, sp. n. (Honduras: San Pedro Sula), Damas kenos Grishin, sp. n. (Peru: Loreto), and Damas lavandas Grishin, sp. n. (Peru: Madre de Dios); and subspecies: in Nymphalidae Rafinesque, 1815: Erebia (Erebia) pawloskii bilibinia Grishin, ssp. n. (Russia: Chukotka) and in Hesperiidae: Telegonus (Rhabdoides) alector ecuadoricus Grishin, ssp. n. (Ecuador: Esmeraldas), Hesperia pahaska tehaska Grishin, ssp. n. (USA: Texas), Hesperia pahaska hidalgo Grishin, ssp. n. (Mexico: Hidalgo), and Hesperia pahaska bajanorta Grishin, ssp. n. (Mexico: Baja California Norte). The following are valid genera: Uraneis Bates, 1868, stat. rest. (not Thisbe Hübner, [1819]) and Virachola F. Moore, 1881, stat. rest. (not Deudorix Hewitson, 1863). The following are valid subgenera, not genera or synonyms: Balonca F. Moore, 1901, stat. rest. of Dodona Hewitson, 1861, Ariconias J. Hall & Harvey, 2002, stat. nov. of Aricoris Westwood, 1851, Thisbe Hübner, [1819], stat. nov. of Lemonias Hübner, [1807], and Pseudonymphidia Callaghan, 1985, stat. nov. of Pachythone H. Bates, 1868. The following are valid species, not subspecies or synonyms: Erebia (Erebia) pawloskii Ménétriés, 1859, stat. conf. (not Erebia (Erebia) theano (Tauscher, 1806) or Erebia (Erebia) stubbendorfii Ménétriés, 1847), Erebia (Erebia) demmia B. Warren, 1936, stat. nov. (not Erebia (Erebia) pawloskii Ménétriés, 1859), Lasaia oaxacensis Grishin, 2024, stat. nov. (not Lasaia sessilis Schaus, 1890), Curvie yucatanensis (Godman & Salvin, 1886), stat. rest. (not Curvie emesia (Hewitson, 1867)), Entheus talaus (Linnaeus, 1763), stat. rest. and Entheus pralina Evans, 1952, stat. nov. (not Entheus priassus (Linnaeus, 1758)), Entheus dius Mabille, 1898, stat. rest., Entheus aequatorius Mabille & Boullet, 1919, stat. rest., Entheus latifascius M. Hering, 1925, stat. rest., and Entheus marmato Salazar & Vargas, [2017], stat. nov. (not Entheus matho Godman & Salvin, 1879), Cecropterus (Thorybes) coxeyi (Williams, 1931), stat. rest. (not Cecropterus (Thorybes) egregius (Butler, 1870)), Cecropterus (Thorybes) chlorothrix (Röber, 1925), stat. rest. (not Cecropterus (Thorybes) virescens (Mabille, 1877)), Telegonus (Rhabdoides) hopfferi (Plötz, 1881), stat. rest. (not Telegonus (Rhabdoides) alector (C. Felder & R. Felder, 1867)), Telegonus (Rhabdoides) gilberti (H. Freeman, 1969), stat. rest. (not Telegonus (Rhabdoides) hopfferi (Plötz, 1881), stat. rest), Telegonus (Rhabdoides) bifascia (Herrich-Schäffer, 1869), stat. conf. and Telegonus (Rhabdoides) tinda (Evans, 1952), stat. conf. (not Telegonus (Rhabdoides) latimargo (Herrich-Schäffer, 1869)), Telegonus (Rhabdoides) parmenides (Stoll, 1781), stat. rest., Telegonus (Rhabdoides) crana (Evans, 1952), stat. nov., and Telegonus (Rhabdoides) cyprus (Evans, 1952), stat. nov. (not Telegonus (Rhabdoides) creteus (Cramer, 1780)), Telegonus (Rhabdoides) erana (Evans, 1952), stat. nov. and Telegonus (Rhabdoides) meretrix (Hewitson, 1876), stat. rest. (not Telegonus (Rhabdoides) chiriquensis Staudinger, 1875), Telegonus (Rhabdoides) grullus (Mabille, 1888), stat. rest. (not Telegonus (Rhabdoides) latimargo (Herrich-Schäffer, 1869)), Pellicia (Hemipteris) meno (Mabille, 1889), stat. rest. and Pellicia (Hemipteris) zamia (Plötz, 1882), stat. rest. (not Pellicia (Pellicia) dimidiata Herrich-Schäffer, 1870), Pellicia (Hemipteris) fumida Mabille, 1889, stat. rest., Pellicia (Hemipteris) aequatoria Williams & Bell, 1939, stat. rest., and Pellicia (Hemipteris) toza Evans, 1953, stat. nov. (not Pellicia (Hemipteris) tyana Plötz, 1882), Pellicia (Hemipteris) naja Steinhauser, 1989, stat. nov. (not Pellicia vecina Schaus, 1902, syn. nov.), Gomalia litoralis Swinhoe, 1885, stat. rest. (not Gomalia albofasciata F. Moore, 1879), Chirgus (Chirgus) biseriatus (Weymer, 1890), stat. rest. (not Chirgus (Chirgus) limbata (Erschoff, 1876)), Chirgus (Chirgus) trisignatus (Mabille, 1875), stat. rest. (not Chirgus (Chirgus) bocchoris (Hewitson, 1874)), Zopyrion (Zopyrion) thyas Evans, 1953, stat. nov. (not Zopyrion (Zopyrion) subvariegata Hayward, 1942), Vacerra cecropterus (Draudt, 1923), stat. rest. (not Vacerra hermesia (Hewitson, 1870)), and Damas corope (Herrich-Schäffer, 1869), stat. rest., Damas cervus (Möschler, 1877), stat. rest., and Damas angulis (Plötz, 1886), stat. rest. (not Damas clavus (Herrich-Schäffer, 1869). The following are valid subspecies, not species or synonyms: Erebia (Erebia) pawloskii sajana Staudinger, 1894 stat. rest. (not Erebia (Erebia) pawloskii pawloskii Ménétriés, 1859), Pellicia (Pellicia) dimidiata brasiliensis R. Williams & E. Bell, 1939, stat. rest. (not a synonym of Pellicia (Hemipteris) meno (Mabille, 1889), stat. rest.), Chirgus (Chirgus) biseriatus barrosi Ureta, 1956, stat. nov., Chirgus (Chirgus) bocchoris cuzcona Draudt, 1923, stat. conf., and Damas angulis ampyx (Mabille, 1891), stat. nov. (not a synonym of Damas clavus (Herrich-Schäffer, 1869)). Phareas serenus Plötz, 1883, syn. rev. is a junior objective synonym of Papilio talaus Linnaeus, 1763. The following are junior subjective synonyms, new or transferred between taxa: Esthemopheles Röber, 1903, syn. rev. of Uraneis Bates, 1868, stat. rest., (not of Thisbe Hübner, [1819]), Eudamus oenander Hewitson, 1876, syn. nov. of Aroma aroma (Hewitson, 1867), Aethilla weymeri Plötz, 1882, syn. rev. of Telegonus (Rhabdoides) chiriquensis Staudinger, 1875, Telegonus fabrici Ehrmann, 1918, syn. rev. of Telegonus (Rhabdoides) latimargo (Herrich-Schäffer, 1869) (not Telegonus (Rhabdoides) alardus (Stoll, 1790), Arteurotia demetrius Plötz, 1882, syn. nov. and Pellicia vecina Schaus, 1902, syn. nov. of Pellicia (Hemipteris) tyana Plötz, 1882, Carystus orope Capronnier, 1874, syn. rev. of Tigasis corope (Herrich-Schäffer, 1869) (not of Damas corope (Herrich-Schäffer, 1869)), Damas woldi Shuey, 2024, syn. nov. of Damas corope (Herrich-Schäffer, 1869), stat. rest., and Thracides polles Godman, 1901, syn. rev. and Perichares tripuncta Draudt, 1923, syn. rev. of Damas angulis ampyx (Mabille, 1891), stat. nov. (not of Damas corope (Herrich-Schäffer, 1869)). Pilodeudorix batikelides (W. Holland, 1920) (not Deudorix Hewitson, 1863) is a new genus-species combination and the following are new species-subspecies combinations: Telegonus (Rhabdoides) bifascia siges Mabille, 1903 (not Telegonus (Rhabdoides) creteus (Cramer, 1780)), Telegonus (Rhabdoides) latimargo aquila Evans, 1952 (not Telegonus (Rhabdoides) alardus (Stoll, 1790), and Gomalia jeanneli levana Benyamini, 1990, (not Gomalia elma (Trimen, 1862)). Lectotypes are designated for 24 taxa: Phareas serenus Plötz, 1883 (the Amazonian 2 region), Peleus aeacus Swainson, 1831 (South America), Entheus matho Godman & Salvin, 1879 (Nicaragua), Eudamus hopfferi Plötz, 1881 (Mexico, likely south-central or southern), Telegonus bifascia (Herrich-Schäffer, 1869) (Brazil), Telegonus chiriquensis Staudinger, 1875 (Panama: Chiriquí), Aethilla weymeri Plötz, 1882 (likely Panama: Chiriquí), Pellicia zamia Plötz, 1882 (likely Venezuela), Pellicia tyana Plötz, 1882 (Brazil: likely São Paulo), Arteurotia demetrius Plötz, 1882 (Brazil: likely Rio de Janeiro), Pellicia violacea Mabille, 1891 (Brazil: likely Rio de Janeiro), Pellicia vecina Schaus, 1902 (Brazil: Rio de Janeiro), Pellicia bilinea Mabille, 1889 (Panama: Chiriquí), Pholisora clytius Godman & Salvin, 1897 (Mexico: Nayarit), Bolla semitincta Dyar, 1924 (Mexico: Colima), Carterocephalus biseriatus Weymer, 1890 (Bolivia), Zopyrion sandace Godman & Salvin, 1896 (Mexico: Guerrero), Goniloba clavus Herrich-Schäffer, 1869 (Southeast and South Brazil), Goniloba corope Herrich-Schäffer, 1869 (the Amazonian region, likely Suriname), Hesperia crataea Hewitson, 1876 (Brazil: Bahia), Proteides cervus Möschler, 1877 (Suriname), Proteides ampyx Mabille, 1891 (Panama: Chiriquí), Thracides polles Godman, 1901 (Panama: Chiriquí), and Carystus orope Capronnier, 1874 (Southeast or South Brazil). Neotypes are designated for six taxa: Papilio priassus Linnaeus, 1758 (Suriname), Papilio talaus Linnaeus, 1763 (the Amazonian region), Papilio peleus Linnaeus, 1763 (French Guiana), Peleus aeacus Swainson, 1831 (French Guiana), Eudamus blasius Plötz, 1881 (Southeast or South Brazil), and Hesperia angulis Plötz, 1886 (Panama: Panama). The type locality of Perichares tripuncta Draudt, 1923 is not in South Brazil, but likely in Panama: Chiriquí, as deduced by genomic comparison. Chlosyne flavula blackmorei Pelham, 2008 and Chlosyne palla sterope (W. H. Edwards, 1870) may be sympatric in British Columbia, Canada, and Lon co Grishin, 2023 is sympatric with Lon ma Grishin, 2023 in Monteverde, Costa Rica. Additional specimens of Cecropterus (Thorybes) viridissimus Grishin, 2023 confirm it as a species-level taxon, and Aethilla toxeus Plötz, 1882 is confirmed as a junior subjective synonym of Cecropterus (Murgaria) albociliatus albociliatus (Mabille, 1877) by further genomic sequencing. The holotype of Cecropterus (Thorybes) oaxacensis Grishin, 2023 is illustrated after being spread. Curiously, Onespa gala (Godman, 1900) and Onespa brockorum Austin & A. Warren, 2009 lack overall genetic differentiation typical of species-level taxa. Furthermore, preliminary taxonomic lists of Entheus Hübner, [1819] and Telegonus (Rhabdoides) Scudder, 1889 (from the clade analyzed in this work) are given. Finally, unless stated otherwise, all subgenera, species, subspecies, and synonyms of mentioned genera, subgenera, and species are transferred together with their parent taxa, and taxa not mentioned in this work remain as previously classified
Balance of Psychological Needs among University Aural Skills Students
No full textThis mixed methods study examined student experiences, perceptions, and motivations in traditional, tertiary aural skills courses. Results from an initial qualitative, instrumental case study led to the development of a four-phase, exploratory sequential design guided by Self-Determination Theory (SDT) and Cognitive Evaluation Theory (CET). Qualitative findings revealed student insights into experiences with course attributes, a need for connection to material and the classroom community, and a desire for an improved aural skills course experience. Quantitative follow up examined student perceptions of the satisfaction and dissatisfaction of the basic psychological needs SDT and CET propose are necessary for student motivation and success. Quantitative results validated and expanded upon qualitative findings. Students were dissatisfied in their need for autonomy, satisfied in their need for relatedness, and reported mixed experiences with their need for competence during aural skills coursework. Mixed methods integration and interpretation of findings through a CET framework showed connections between student descriptions of course events and survey responses. Clear pathways for an improved student experience through increased attention to autonomy and competence support at both the instructional and curricular level are outlined. This research adds student voices to ongoing discussions in aural skills literature regarding student-centered curricular reforms, as well as an example of a domain and context specific application of SDT research into motivation in music education.Advisor: Rhonda J. Fuelbert
Contraceptive Hormone Influences on the Role of Primary Reinforcement and Reinforcer-enhancement in Nicotine Self-administration
Get PDFHormonal contraceptives contain a synthetic estrogen (e.g., ethinyl estradiol/EE) and/or a synthetic progestin (e.g., levonorgestrel/LEVO) and can exacerbate nicotine intake. However, whether altered intake reflects changes in nicotine reinforcement or enhancement by nicotine of co-occurring reinforcers is unknown. This reinforcer-enhancement effect is evidenced in rats when nicotine self-administration is increased by the presence of a visual stimulus (VS) reinforcer. This dissertation examined the effects of EE and LEVO on nicotine reinforcement and reinforcer-enhancement in ovary-intact female Sprague-Dawley rats. Rats were implanted with a jugular catheter and assigned to receive daily injections of EE (Vehicle, 0.125 [Low], or 0.18 [High] μg/day; Experiment 1) or LEVO (Vehicle, 0.3 [Low], or 0.6 [High] μg/day; Experiment 2) throughout self-administration. Rats were assigned to respond for 0.03 or 0.06 mg/kg/inf nicotine or saline during two phases. Each consisted of ten sessions on a Variable Ratio (VR)-3 schedule: the Infusion Only phase, responding only for their assigned solution, and the Infusion+VS phase, responding for their assigned solution and a 30-second VS. The Infusion+VS phase also included five sessions on a Progressive Ratio (PR) schedule. In Experiment 1, 0.06 but not 0.03 mg/kg/inf nicotine maintained self-administration during the Infusion Only phase – self-administration was unchanged by EE. EE did alter self-administration during the Infusion+VS phase. For Infusion+VS VR3 sessions, Vehicle rats responded more for 0.03 than 0.06 mg/kg/inf nicotine or saline, while Low EE rats responded more for 0.03 and 0.06 mg/kg/inf nicotine than saline. High EE rats did not self-administer any nicotine dose. For Infusion+VS PR sessions, Vehicle and Low EE rats self-administered 0.03 and 0.06 mg/kg/inf nicotine more than saline. In Vehicle but not Low EE rats, 0.03 mg/kg/inf nicotine maintained greater self-administration than 0.06 mg/kg/inf nicotine. High EE rats only self-administered 0.06 mg/kg/inf. In Experiment 2, we replicated Experiment 1 insofar that 0.06 but not 0.03 mg/kg/inf nicotine without the VS maintained self-administration. Responding during the Infusion+VS phase replicated that of Vehicle rats in Experiment 1. LEVO did not alter self-administration during any phase. EE and LEVO disrupted normal estrous cycling, and EE increased uterine weights. Thus, our EE and LEVO doses were physiologically effective.Advisor: Rick A. Bevin
A Case Study on Readiness of Engineers in Agricultural Technology Start-ups
Get PDFThis dissertation explores the perceptions of practicing engineers regarding the skills necessary to be workforce-ready at agricultural technology (ag-tech) start-ups in the Midwestern United States. A qualitative case study methodology is leveraged, combining both interview and job description data. Given their uniqueness, the study divides the ag-tech start-up industry into two subcases: livestock and cropping systems. The Work Readiness Integrated Competence Model (WRICM) is used as the theoretical framework for this study and informs the conceptual framework and analysis processes. The study identified skills that fit into thirteen distinct categories, which are further grouped into four overarching resource groups. Skills identified in this study that are common in engineering readiness literature more broadly included problem solving, critical thinking, creativity and innovation, leadership, self-management, interpersonal communication, teamwork, and technical engineering skills. Skills of particular interest to the ag-tech start-up industry that were less commonly mentioned in literature included research, systems thinking, information technology (IT), and accountancy and marketing skills. This study offers multiple recommendations for students, faculty, and industry practitioners. It highlights the need to attract more engineers to this rapidly growing sector and encourages students and engineers to use the identified skills as a benchmark for industry readiness. Additionally, academics can leverage these findings to integrate essential non-technical skills—such as communication, teamwork, systems thinking, and agricultural knowledge—into engineering curricula for engineering students that may enter the ag-tech field. Ag-tech start-ups can utilize this study as a framework for evaluating an engineer’s preparedness and identifying areas for skill development. Lastly, the study paves the way for further research on workforce readiness in engineering, agriculture, start-ups, and the ag-tech industry.Advisor: Logan A. Perr
A Survey of and Performance Guide to Representative Flute Music by Two Twentieth-Century Serbian Composers: Ljubica Marić and Enriko Josif
Get PDFFlute pieces by twentieth-century Serbian composers Ljubica Marić and Enriko Josif are little-known gems of modern repertoire that are almost completely unknown outside Serbia. Unique in their styles, these works illustrate the composers’ close relationship to the Serbian culture in which they lived and the religions they practiced. In addition, these works reflect the time they were created in, and are, therefore, modern with a distinctive sound. This document presents a study of seven selected flute works by these two important Serbian composers, places them in historical context, and reveals influences from both Serbian religious music (Orthodox and Jewish) and Balkan folk music.The first chapter of this document establishes the value of the works by Josif and Marić, the importance of this research, and very real research challenges: the works are in general only available in difficult-to-decipher manuscript, sometimes in copies not by the composer, with conflicting information, and these manuscript sources are hard to locate. Almost all important biographical and secondary material is in Serbian.The second chapter presents biographical information for Ljubica Marić and examines three of her works: Song for the Flute, The Wondrous Milligram for flute and soprano, and The Flute Solo with Coda in Piano. Research on these three pieces provides formal analysis, motivic discussion, and possible programmatic aspects of composition (in Marić’s duet for flute and soprano). All three pieces were influenced by Serbian Octoechos, the tonal system for organizing Byzantine Chant of the Christian Orthodox religion, and therefore a brief review of the system and its history is provided, and the relationship between these three pieces and the melodies of Serbian Octoechos is clarified.The third chapter of this document provides biographical information on Enriko Josif and discusses three of his pieces for solo flute: Psalmody 1, Psalmody 2, Ballade, as well as Monody, his duet for flute and harp. Research on these four pieces provides formal analysis, motivic analysis, and historical influence. For instance, Psalmody 2 was inspired by Psalm 137 (By the Rivers of Babylon) from the Hebrew Bible and its structure reflects this. A comparison of the two composers’ approach to composition concludes the study.Advisor: John Baile
Implications of Type IV Pilus Retraction for DNA Uptake by \u3cem\u3eAcinetobacter baumannii\u3c/em\u3e
Get PDFHorizontal gene transfer (HGT) via natural competence allows bacteria to incorporate extracellular DNA (eDNA) into their genomes, facilitating genetic diversity and adaptation. In Acinetobacter species, natural competence depends on DNA binding and uptake mediated by type IV pili (T4P). T4P are dynamic extracellular filaments composed primarily of the major pilin subunit PilA, along with a few minor subunits. T4P drive a range of cellular functions including twitching motility, biofilm formation, and DNA uptake, with some functions dependent on pilus retraction and others not. However, how Acinetobacter T4P bind DNA and how T4P/eDNA interactions impact biofilm formation remain unclear. Here, I present my results probing 1) the mechanisms by which Acinetobacter T4P bind DNA and 2) the structural basis for differences in DNA uptake between naturally-occurring clonal groups of Acinetobacter baumannii.
To identify which pilus subunits are eDNA receptors in Acinetobacter, we recombinantly expressed Acinetobacter T4P subunits and measured binding to DNA as well as T4P functions in A. baumannii transposon mutants of T4P subunits. We found that FimT is not required for pilus assembly or twitching motility but promotes biofilm formation. Flow cytometry further showed that a fimT mutant is defective in DNA uptake. Although FimT does not contain known DNA-binding motifs, computational structure prediction suggests possible mechanisms for direct interactions with dsDNA.Acinetobacter bacteria, including International Clone I (IC-I) and International Clone II (IC-II) strains, show variable phenotypes in assays of type IV pilus-dependent functions. Here we show that this variation is the result of variable efficiency in pilus retraction between pilus subtypes and from that, a differential balance between retraction-dependent and retraction-independent functions. We define type IV pilus subtypes based on the sequence of the major subunit, PilA. In both naturally-occurring pilA variants from the IC-I and IC-II groups and isogenic strains complemented with IC-I or IC-II pilA, the IC-I pilus subtype promotes greater twitching motility and DNA-uptake while the IC-II pilus subtype promotes biofilm formation while showing reduced capacity for DNA-uptake and twitching motility, similar to a retraction-deficient mutant and consistent with the hypothesis that pilus retraction of the IC-II pilus is naturally deficient.Advisor: Kurt H. Piepenbrin
North Central Extension Risk Management Education Center Helps Producers Manage Risks
No full textEducating producers to manage risk and position their farm or ranch for future growth and success is the fundamental purpose of the Extension Risk Management Education (ERME) program.
The ERME program, funded by United States Department of Aagriculture’s National Institute of Food and Agriculture, provides training to help producers learn new strategies to manage complex and growing agricultural risks.
Established in 2001 and located at the University of Nebraska-Lincoln Agricultural Economics Department, the North Central Extension Risk Management Education Center (NCERMEC) has a long history of supporting risk management education programs serving producers in the region. NCERMEC, in conjunction with three other regional centers, conducts an annual competitive process to fund outcomes-based risk management education projects designed to empower producers with the knowledge and tools necessary to navigate the uncertainties inherent in agricultural operations.
Includes a list of 2025 funded projects