Novel Paleoclimate and Paleoenvironmental Applications of Stable and Radiogenic Isotope and Elemental Geochemistry from the Holocene through the Cretaceous

Anthropogenic influence on modern climate and the environment is unambiguous and bears profound implications for agriculture, water availability, and natural resource management. These influences are global in extent and require critical examinations of past climatic and environmental perturbations in the geological record to predict the magnitude of anticipated changes (e.g. surface temperature increase) that will impact humanity in the future. This dissertation explores the use of existing and novel geochemical proxies for environmental information ranging from atmospheric circulation patterns of the Pleistocene/Holocene to coastal marine temperatures and volcanism of the Late Cretaceous. The initial focus of this research has centered on the application of carbonate clumped isotope (Δ47) paleothermometry to marine mollusk fossils in order to reconstruct marine temperatures preceding, during, and after the Cretaceous-Paleogene (K-Pg) extinction. The K-Pg boundary interval serves as an important analogue to modern and future climate projections, with atmospheric CO2 concentrations estimated at ~400 to 1100 ppm (compared to an annual average of 402.8 ppm in 2016) and a world lacking significant continental ice sheets. The K-Pg boundary is also known for pervasive terrestrial and marine extinctions including the demise of dinosaurian groups. These methods revealed Δ47-derived coastal marine temperatures from the ancient Mississippi Embayment and Atlantic Coast ranging from 7 to 25 °C, which compare closely to modern values in the range of 10 to 29 °C. The similarity between modern and reconstructed paleotemperatures suggests that the surface temperatures required at the subtropics for an unglaciated world may be closer to those observed in the modern than originally believed and implies a shallow equator-to-pole thermal gradient. Cold paleotemperatures along the Atlantic Coast near New Jersey (3 to 14 °C) may provide evidence for the presence of the Gulf Stream current, and subsequent North Atlantic return flow as early as the Campanian/Maastrichtian. The temperature ranges reconstructed for these sites also compare well to marine temperatures determined using other proxy methods, with the exception of the TEX86 organic geochemical temperature proxy, which may be seasonally biased towards summer temperatures. Coupled with the temperatures reconstructed from Δ47 values, we have developed a unique proxy for environmental mercury concentrations, [Hg], in the past using the same mollusk fossils from before, during, and after the K-Pg boundary interval. This work represents the first deep-time application of [Hg] records in biogenic carbonates. We have measured both [Hg] and Δ47 values from globally-distributed specimens across a latitudinal range from 70 °N to 67 °S. We found covariation between elevated marine temperatures (~7 to 10 °C excursions) and peak [Hg] between 17 to 42 ng g-1 (relative to a background of ~0 to 5 ng g-1) immediately prior to the K-Pg extinction and coinciding with the onset of the main eruptive phase of the Deccan Traps Large Igneous Province (LIP). Evidence of a global signal of volcanogenic emissions (e.g. CO2 and gaseous elemental Hg) and changing climate prior to the K-Pg boundary suggest causality and serve to clarify the role of the Deccan Traps in terms of extinction patterns. This work also reveals the potential of [Hg] in biominerals at other critical intervals of the geological record in addressing questions relating to LIP volcanism and environmental mercury cycling.PHDEarth and Environmental SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144022/1/meyerkw_1.pd

Extreme rays of the (N,k)(N, k)-Schur Cone

We discuss several partial results towards proving Dennis White's conjecture on the extreme rays of the $(N,2)$-Schur cone. We are interested in which vectors are extreme in the cone generated by all products of Schur functions of partitions with $k$ or fewer parts. For the case where $k =2$, White conjectured that the extreme rays are obtained by excluding a certain family of "bad pairs," and proved a special case of the conjecture using Farkas' Lemma. We present an alternate proof of the special case, in addition to showing more infinite families of extreme rays and reducing White's conjecture to two simpler conjectures.Comment: This paper has been withdrawn by the authors due to a misinterpretation of the generalized Littlewood-Richardson rule in several proof

Chart a Course for Holistic Admissions Transformation Using an Interprofessional Model

Implementing comprehensive holistic admissions requires schools to evaluate, and perhaps think differently, about recruitment and marketing, admission and retention practices, as well as the extent to which these practices align with the institutional mission and goals. Developing and implementing holistic admissions is time, and resource intensive and requires tremendous leadership and faculty support. This course is designed to give physical therapy educators background rationale and a formal structure to operationalize comprehensive holistic admissions, from recruitment to workforce placement, including strategies for gaining higher administration support. The Dean, former Associate Dean for Academic Affairs, and Admissions Committee Chair of the College of Allied Health Professions (CAHP) at the University of Nebraska Medical Center will share their experience with developing, implementing and evaluating comprehensive holistic admissions for the entire college, consisting of 14 programs. The interactive course format will invite participants to engage the presenters as it pertains to the participants’ unique journeys with implementing holistic admission practices at their own institutions, allowing for a rich exchange of information and experiences.https://digitalcommons.unmc.edu/cahp_pres/1000/thumbnail.jp

The biogeography and functional ecology of tropical soil microorganisms

Tropical ecosystems are some of the most diverse and productive ecosystems on the planet. These ecosystems are also some of the most threatened worldwide and this is largely driven by agricultural expansion. Predicting biotic responses to such forms of environmental change is a challenge that requires an increased understanding of the factors structuring these communities in both pristine environments as well as environments that are undergoing environmental change. Studying patterns in the spatial structure of communities can provide important insights into ecological and evolutionary processes structuring communities. Combining such approaches with analyses of the distribution of activity and the genomic content of communities can help us better understand relationships between community structure and function. I explore the topics of microbial spatial scaling, activity, and gene content in both pristine tropical rainforest environments as well as tropical regions undergoing agricultural conversion. I first pose a fundamental question in microbial spatial ecology, i.e. why do microorganisms tend to show weaker spatial patterns than macro-organisms? I show that trees and soil microorganisms differ in the rates at which their communities change over space. I test the hypothesis that low rates of spatial turnover in microbial communities are an artifact of how we assess the community structure of microbial communities and show that sampling extent is likely the main driver of these differences. Next, I examine a Central Africa ecosystem that is undergoing conversion to agriculture. I show that there are numerous indications of biotic homogenization in these soil microbial communities and that the active fraction of the community shows a more pronounced response to environmental change. Finally, I examine two microbial processes in the Amazon Basin that have been reported to change following conversion to agriculture: methane production and methane consumption. I investigate changes to the genes and taxa involved in these processes and propose a new conceptual framework for how these processes might be changing. Work in this thesis contributes to a broader understanding of the spatial and functional ecology of tropical microorganisms and offers perspectives useful for those interested in predicting and mitigating the impacts of environmental change on these communities.2019-02-1

Reassessment of mid-Carboniferous glacial extent in southwestern Gondwana (Rio Blanco Basin, Argentina) inferred from paleo-mass transport of diamictites

Late Paleozoic glacial diamictites occur in many localities in western Argentina, indicating that the region was strongly affected by glaciation during the mid-Carboniferous (late Serpukhovian–early Bashkirian). In most instances these diamictites are found in steeply walled paleovalley settings in the Andean Precordillera. This study presents new data from a locality north of the Precordillera that suggests an additional, distinct, volume of ice existed in the region during the Carboniferous. The glacigenic diamictites in the Rio Blanco Basin were ultimately emplaced as gravity flows, precluding inferences of paleo-ice volume. Fold nose orientation and soft-sediment groove orientations within the diamictites indicate that the deposits were emplaced from north to south, suggesting that glacial ice was most likely not sourced from the proto-Precordillera at this locality, requiring the need for another ice center to the north of the basin. Diamictite facies indicates that the sediment was initially supplied to the study area by a warm-based glacier.Fil: Gulbranson, Erik L.. University of California at Davis; Estados Unidos. University of Wisconsin; Estados UnidosFil: Isbell, John L.. University of Wisconsin; Estados UnidosFil: Montañez, Isabel P.. University of California at Davis; Estados UnidosFil: Limarino, Carlos Oscar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Marenssi, Sergio Alfredo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Meyer, Kyle. University of California at Davis; Estados UnidosFil: Hull, Clara. University of California at Davis; Estados Unido

Multi-campus DPT Programmatic Development in a Public University: Leadership Considerations

Background/Purpose: Institutional pressure for expanded revenue streams, coupled with workforce development needs to insure patient access of health resources both drive programmatic expansion of healthcare education programs across multiple campus sites. Such expansion is predicated on deliberate planning and resource acquisition for effective course delivery and successful programmatic outcomes. The University of Nebraska Medical Center’s College of Allied Health Professions opened a second campus site in 2016, located 185 miles from the main campus and the urban corridor of the state. The Doctor of Physical Therapy (DPT) program (and four additional allied health professions) modified traditional course delivery to create a synchronous learning environment, with core and adjunct faculty members actively engaged on both campuses. This administrative case report describes areas of critical consideration for faculty and administrators when expanding DPT programs across multiple sites. Strategies associated with successful implementation are addressed. Case Description. The process of program expansion and implementation are outlined, including challenges, subsequent actions, and successful strategies. Critical elements of program planning and implementation are categorized in the context of: Essential Infrastructure, Essential Functions, and identification of Essential Outcomes to provide evidence that the distance-based curriculum effectively addresses student learning needs. Outcomes: Key considerations related to “essential infrastructure: include resources such as: Administrative/leadership support; community engagement and relationships; qualified personnel; space; equipment; and basic technology (including deployment of a “STAT” team of student technology assistants). “Essential functions” include: Changes associated with the admission process and messaging; curriculum modifications; instructional design assistance; reformulated interprofessional education and practice experiences; faculty development and scholarship, and the serious need to empanel a bi-campus faculty “response team” for vigilance in pragmatic detail and parity of learning experiences. “Essential Outcomes” address the critical focus of protecting a singular program concept from shifting to an asynchronous, satellite format, as well as describing assessment strategies at various levels within the institution. Discussion: The ability to maintain quality brand reputation during multi-campus expansion of a DPT program requires the leverage of resources and talent from multiple and varied stakeholders. This administrative case report describes essential factors that must be deliberately addressed by campus administrators and faculty for successful implementation and outcomes

A Cold Nearby Cloud Inside the Local Bubble

The high-latitude Galactic H I cloud toward the extragalactic radio source 3C 225 is characterized by very narrow 21 cm emission and absorption indicative of a very low H I spin temperature of about 20 K. Through high-resolution optical spectroscopy, we report the detection of strong, very narrow Na I absorption corresponding to this cloud toward a number of nearby stars. Assuming that the turbulent H I and Na I motions are similar, we derive a cloud temperature of 20 (+6, -8) K (in complete agreement with the 21 cm results) and a line-of-sight turbulent velocity of 0.37+/-0.08 km/s from a comparison of the H I and Na I absorption linewidths. We also place a firm upper limit of 45 pc on the distance of the cloud, which situates it well inside the Local Bubble in this direction and makes it the nearest-known cold diffuse cloud discovered to date.Comment: 11 pages, 3 figures, accepted for publication in ApJ Letter