Webs of activity in online course design and teaching

In this study, we followed three faculty members' experiences with designing and teaching online courses for the first time. In order to complete the activity, the faculty members had to work -collaboratively with others across the university. Activity theory provided a framework within which to study faculty members' collaborative activities with members of different activity systems that had different goals, tools, divisions of labor and accountabilities. In concordance with activity theory, such differences led to contradictions, disturbances, and transformations in thinking and work activities. The results of the study have implications for individuals and systems undertaking technology integration in teaching

The supposed dissipation of figural imagery in Mamluk art: a study of Mamluk iconography

The arts of the Mamluks are considered a particularly rich field of study stretching over a nearly three hundred year period. Diverse in their make-up, the progression and development of this art began with strong Ayyubid influences that quickly evolved into a style that was uniquely Mamluk. While many historians have argued that figural imagery all but disappeared in these later progressions of Mamluk art, most notably following the reign of the Mamluk sultan al-Nasir Muhammad (1309-1341), the reality of these conclusions is much more complex. Indeed, the lack of conclusively dated materials from these later periods has been a significant factor in these early claims regarding Mamluk figural imagery. However, given the recent study released by Rachel Ward that re-dated Medieval Syrian and Egyptian glass, as well as a careful reexamination of other portable arts of this period, it becomes clear that the production of anthropomorphic and zoomorphic imagery was by no means halted during the reign of al-Nasir Muhammad, but rather was relegated to artwork that did not bear the official court titulature of amirs and sultans. In this sense, figural imagery played a important, albeit secondary, role in the visual expressions of the Mamluk ruling elite

Multiscale regulation of cellular mechanical properties

Thesis (Ph.D.)--Boston UniversityIn vivo, cells routinely experience mechanical stresses and strains in the form of circulatory pressure and flow, peristalsis ofthe gut, and airway inflation and deflation. Even on the microscale, all adherent cells apply contractile force to the extracellular matrix and to neighboring cells. Cells respond to these external forces both passively and actively. Passively, cells need to deform in a way that is tissue and function appropriate. Actively, cells use local mechanoreceptors present on their surface to trigger changes in global cell behavior. Dysregulation of cell responses to force are hallmarks of diseases such as atherosclerosis, asthma and cancer. Given the pluripotent role of cell mechanics in both normal cell behavior and disease, cell regulation of mechanical properties has become a major area of focus in biology. In this dissertation, we explore passive mechanical properties and active mechanical responses of cells on the subcellular, single cell and multicellular length scales. In Aim 1, we developed a new tool, called cell biomechanical imaging, for mapping intracellular stiffness and prestress. We have demonstrated a linear relationship between these two quantities, both at the whole cell and subcellular levels, which suggests prestress may be a unifying mechanism by which cells and tissues tune their mechanical properties. In Aim 2, we investigated how coordinated changes in cytoskeletal tension lead to cell reorientation. Previous research has shown that in response to strain applied through focal adhesions, the actin cytoskeleton promptly fluidizes and then slowly resolidifies. Using both experiments and a mathematical model, we found that repeated interplay ofthese phenomena was a driving force behind cytoskeletal reorganization during cell reorientation. It was previously hypothesized that the purpose of cytoskeletal remodeling in response to strain was to minimize changes in intracellular mechanical tension and maintain it at a preferred level. This feedback control mechanism, which balances forces between the cell and its microenvironment, is termed "tensional homeostasis." The dominant paradigm in vascular biology is that tensional homeostasis exists across multiple length and time scales. However, our results from Aim 2 challenged this idea; reoriented cells did not maintain steady levels of contractile force. In Aim 3, we investigated tensional homeostasis and its existence at multiple length scales. We found that cells do not have a preferred level of tension at the subcellular or single cell levels. However, in a cluster of confluent cells, contractile tension is maintained, the more so as cluster size increases. Together, the results of this dissertation emphasize the importance ofa multiscale approach to mechanobiology. Cells and tissue are hierarchically ordered systems that use mechanical stress (prestress) to tune their mechanical properties and responses across lengthscales. Thus, it is important to consider not just the behavior of separate components of each of these systems, but the behaviors that emerge when they interact with one another

Parental Deployment and Healthcare Utilization in Adolescents with Migraines and Other Somatic Symptoms

Somatic symptoms in adolescents are associated with psychosocial stress. Parental military deployment can function as a stressor for adolescents. A retrospective cohort study was developed exploring relationships between health care utilization, a proxy for symptomatology, and sponsor deployment in adolescents with somatic symptoms. Data was obtained from the Military Health System Data Repository. Migraine headaches was the most common somatic symptom diagnosis. Parental deployment was overall associated with a 27% decrease in visits for somatic symptoms. For adolescents whose sponsor was female, deployment was associated with a 34% decrease in visits. This pattern is inconsistent with prior research on somatic symptoms and psychosocial stressors. Potential causes of this discrepancy are discussed in the context of military family life

Identification of a conditionally essential heat shock protein in Escherichia coli

Protein D48.5 was recognized as a heat-inducible protein of Escherichia coli during the screening of a group of random, temperature-inducible Mud-Lac fusion mutants. Physiological and genetic analysis demonstrated that (i) the structural gene for this protein, designated htpI, is a member of the o32-dependent heat shock regulon, (ii) at 37[deg]C the synthesis of protein D48.5 is nearly constitutive, increasing slightly with growth rate in media of different composition, and (iii) this protein is essential for growth at high temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31386/1/0000299.pd

First imported Plasmodium ovale malaria in Central America: case report of a Guatemalan soldier and a call to improve its accurate diagnosis

The Mesoamerican Ministers of Health have set 2020 as the target for malaria elimination to be achieved in the region. Imported malaria cases are a potential threat to countries attempting elimination or working to prevent resurgence. We report the first imported Plasmodium ovale infection with molecular confirmation in Central America, which occurred in a Guatemalan soldier that had been deployed in Africa. The obstacles for its diagnosis using the standard microscopy technique and the need to improve its detection are discussed

Vadose-Zone Alteration of Metaschoepite and Ceramic UO2 in Savannah River Site Field Lysimeters

Uranium dioxide (UO2) and metaschoepite (UO3•nH2O) particles have been identified as contaminants at nuclear sites. Understanding their behavior and impact is crucial for safe management of radioactively contaminated land and to fully understand U biogeochemistry. The Savannah River Site (SRS) (South Carolina, USA), is one such contaminated site, following historical releases of U-containing wastes to the vadose zone. Here, we present an insight into the behavior of these two particle types under dynamic conditions representative of the SRS, using field lysimeters (15 cm D x 72 cm L). Discrete horizons containing the different particle types were placed at two depths in each lysimeter (25 cm and 50 cm) and exposed to ambient rainfall for 1 year, with an aim of understanding the impact of dynamic, shallow subsurface conditions on U particle behavior and U migration. The dissolution and migration of U from the particle sources and the speciation of U throughout the lysimeters was assessed after 1 year using a combination of sediment digests, sequential extractions, and bulk and μ-focus X-ray spectroscopy. In the UO2 lysimeter, oxidative dissolution of UO2 and subsequent migration of U was observed over 1–2 cm in the direction of waterflow and against it. Sequential extractions of the UO2 sources suggest they were significantly altered over 1 year. The metaschoepite particles also showed significant dissolution with marginally enhanced U migration (several cm) from the sources. However, in both particle systems the released U was quantitively retained in sediment as a range of different U(IV) and U(VI) phases, and no detectable U was measured in the lysimeter effluent. The study provides a useful insight into U particle behavior in representative, real-world conditions relevant to the SRS, and highlights limited U migration from particle sources due to secondary reactions with vadose zone sediments over 1 year.Peer reviewe

Evanescent Wave Fiber Optic Biosensor for Salmonella Detection in Food

Salmonella enterica is a major food-borne pathogen of world-wide concern. Sensitive and rapid detection methods to assess product safety before retail distribution are highly desirable. Since Salmonella is most commonly associated with poultry products, an evanescent wave fiber-optic assay was developed to detect Salmonella in shell egg and chicken breast and data were compared with a time-resolved fluorescence (TRF) assay. Anti-Salmonella polyclonal antibody was immobilized onto the surface of an optical fiber using biotin-avidin interactions to capture Salmonella. Alexa Fluor 647-conjugated antibody (MAb 2F-11) was used as the reporter. Detection occurred when an evanescent wave from a laser (635 nm) excited the Alexa Fluor and the fluorescence was measured by a laser-spectrofluorometer at 710 nm. The biosensor was specific for Salmonella and the limit of detection was established to be 103 cfu/mL in pure culture and 104 cfu/mL with egg and chicken breast samples when spiked with 102 cfu/mL after 2–6 h of enrichment. The results indicate that the performance of the fiber-optic sensor is comparable to TRF, and can be completed in less than 8 h, providing an alternative to the current detection methods