1,506 research outputs found
Structural studies of acid phosphatases from pathogenic bacteria
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on March 23, 2009)Vita.Thesis (Ph.D.) University of Missouri-Columbia 2007.Acid phosphatases are important, ubiquitous, and diverse group of enzymes that catalyze the transfer of phosphoryl from phosphomonoester to water forming inorganic phosphate and alcohol. These enzymes play critical roles in numerous processes and pathways including virulence. It has been suggested that the pathogenic bacteria Francisella tularensis utilizes an acid phosphatase to aid in the escape from the phagasome. As part of this research, the three dimensional X-ray crystal structures of three phosphatases from F. tularensis were determined. The three structures from F. tularensis were AcpA, HAP, and class C. Parallel to those structural studies homologous structures of class C acid phosphatases were determined from Haemophilus influenzae and Bacillus anthracis, those structures are also reported here. In all five unique acid phosphatase structures were determined in this research project that have led to a better understanding of the novelty of catalytic mechanisms, a clearer understanding of substrate binding, and a new foundation for structural investigation.Includes bibliographical reference
Flow Measurements Using Particle Image Velocimetry in the Ultracompact Combustor
The potential for the ultracompact combustor (UCC) lie in future research to reduced fuel consumption and improved engine performance. Velocity measurements performed on the UCC test rig at the Air Force Institute of Technology revealed flow patterns and time-averaged turbulence statistics for data taken burning hydrogen fuel in a straight and a curved cavity vane configuration. Over an equivalence ratio from 0.7 to 1.5, the straight vane configuration showed spanwise velocity decreased linearly with distance from the cavity vane over the width of the main channel. Increasing the flow rates and holding the equivalence ratio and ratio of cavity to main airflow rates constant, flow velocities in the main channel showed an increase with the curved circumferential configuration but a decrease with the straight circumferential configuration. Turbulence intensity is expected to be a major contributing factor, specifically since measured at 15% and 21% in the main channel for the straight and curved configurations, respectively. The results also show how the radial vane cavity (RVC) created strong vorticity throughout the main flow supporting a recirculation zone for mixing. Peak vorticity occurred farthest from the cavity vane suggesting the angle of the radial vane cavity is effective in generating increasing flow rotation
Testing and Improving a UAV-Based System Designed for Wetland Methane Source Measurements
Wetlands are the single highest emitting methane source category, but the magnitude of wetland fluxes remains difficult to fully characterize due to their large spatial extent and heterogeneity. Fluxes can vary with land surface conditions, vegetation type, and seasonal changes in environmental conditions. Unmanned aerial vehicles (UAVs) are an emerging platform to better characterize spatial variability in these natural ecosystems. While presenting some advantages over traditional techniques like towers and flux chambers, in that they are mobile vertically and horizontally, their use is still challenging, requiring continued improvement in sensor technology and field measurement approaches. In this work, we employ a small, fast response laser spectrometer on a Matrice 600 hexacopter. The system was previously deployed successfully for 40 flights conducted in a four-day period in 2018 near Fairbanks, Alaska. These flights revealed several potential areas for improvement, including: vertical positioning accuracy, the need for sensor health indicators, and approaches to deal with low wind speeds. An additional set of flights was conducted this year near Antioch in California. Flights were conducted several meters above ground up to 15-25 m in a curtain pattern. These curtains were flown both upwind and downwind of a tower site, allowing us to calculate a mass balance methane flux estimate that can be compared to eddy covariance fluxes from the tower. Testing will better characterize the extent to which altitude drifts in-flight and how GPS values compare with measurements from the onboard LIDAR, as well as the agreement between two-dimensional wind speed and direction on the ground versus measured onboard the UAV. Hardware improvements to the sensor and GPS are being considered to help reduce these sources of uncertainty. Results of this testing and how system performance relates to needs for quantifying wetland fluxes, will be presented
In Memoriam: Daniel J. Meltzer
Sedan Ă„r 2006 har den syntetiskt framstĂ€llda drogen spice existerat i Sverige, men först Ă„r 2008 blev drogen populĂ€r och tidningar började rikta uppmĂ€rksamhet mot den. Genom att drogen kan byta skepnad i uppbyggnaden kan den förbli laglig, dĂ€rför kan egentligen namnet âspiceâ inte betraktas som ett enhetligt begrepp. VĂ„rt syfte med denna studie blev att granska hur drogen spice beskrivs i tidningar och forskning. Ăven hur drogen betraktas gĂ€llande psykosociala och medicinska avseenden. Detta i förhĂ„llande till socialkonstruktivistiskt perspektiv. Den metod som vi valde att anvĂ€nda oss av i studien var kvantitativ innehĂ„llsanalys. Genom analys av 80 stycken svenska tidningsartiklar hĂ€mtade ur databasen mediearkivet, samt vetenskapliga artiklar och litteratur har vi besvarat vĂ„ra frĂ„gestĂ€llningar. De resultat vi fick frĂ„n analyser visade pĂ„ att tidningar kan vara av betydande roll för ungdomars attityder. Tidningar kan utföra bland annat skrĂ€mselpropaganda för att upplysa och förhindra brukandet av spice, dessvĂ€rre visar resultatet en motsatt effekt. Forskning visar att bruk av spice kan pĂ„verka relationer och arbete negativt. Dessutom Ă€r nĂ„gra bieffekter av spice bröstsmĂ€rtor, vanförestĂ€llningar, sjĂ€lvmordstankar och hjĂ€rtstopp
Public Health Communicable Disease Reporting Laws: Managed Care Organizations\u27 Laboratory Contracting Practices and Their Implications for State Surveillance and Reporting Statutes
This report, prepared for the U.S. Centers for Disease Control and Prevention by the GWU Center for Health Services Research & Policy (CHSRP), presents findings from analyses of contractual specifications related to public sector managed care contractors\u27 duties and activities related to public health surveillance and education activities for communicable disease control, specifically HIV/AIDS, sexually transmitted diseases, and tuberculosis
Handel\u27s Messiah and Gloria in Excelsis Deo
Program listing performers and works performe
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