The role of genetic background on the phenotypic severity of the osteogensis imperfecta murine (oim) COLIA2 gene mutation throughout postnatal development

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 May 1, 2009)Vita.Thesis (Ph.D.) University of Missouri-Columbia 2006.Osteogenesis imperfecta (OI) is a diverse disease of type I collagen, the main structural protein in the body. It has been well documented that related individuals harboring the same OI-causing mutation can have very different clinical outcomes. However, the relationship between genotype and clinical outcome remains unclear. The goal of this study was to further examine the genotype-phenotype relationship with the long-term goal of identifying modifier genes that impact the quality of bone. Modifier genes influence clinical outcome by interacting with genes known to impact bone quality such as the type I collagen genes. As gene expression changes throughout development, we sought to determine if age-related changes in bone quality occurred. To this end, the same OI-causing mutation was studied on two genetic backgrounds, one with reduced bone strength (C57) and one with variable bone strength (outbred). Wildtype and oim animals of each strain were then analyzed at one, two and four months of age to assess bone shape and strength as well as biochemical parameters. This work showed strain related differences at all ages examined, but the presence of the oim mutation overrides these differences. Bones from oim animals of either strain have altered bone geometry and reduced biomechanical strength as compared to wildtype, with C57-oim animals having a more severe phenotype than outbred oim animals. Oim animals also had altered mineral composition and reduced amounts of type I collagen, which were strain specific. Taken together, these data indicate a role for genetic background in determining phenotypic severity, although some parameters are more affected by genetic background than others.Includes bibliographical reference

Pacific sea surface temperature associations with southwestern United States summer rainfall and atmospheric circulation

Pacific sea surface temperatures (SSTs) are examined for their associations with (1) summer rainfall, and (2) the latitude location of the mid-tropospheric subtropical high pressure ridge (STR) in the southwestern United States during 1945 to 1986. Extreme northward (southward) displacements of STR are associated with wet (dry) summers over Arizona and an enhanced (weakened) gradient of SST off the California and Baja coasts. These tend to follow winters marked by positive (negative) phases of the PNA, Pacific/North America, teleconnection pattern. Recent decadal variations of Arizona summer rainfall (1950s wet; 1970s dry) appear similarly related to southwestern United States synoptic circulation and eastern Pacific SSTs

Muscle loading effects on bone parameters in the oim mouse model [abstract]

Faculty Mentor: Dr. Charlotte Phillips, BiochemistryAbstract only availablePrevious studies have shown that mechanical loading on the skeleton acts as an anabolic stimulus, inducing changes in bone geometry, bone mineral density, and mechanical properties. Increases in these properties may improve bone quality as seen by increased bone density following sustained physical activity, and the increase may be due to increased muscle contraction. Much data exists on the effects of unloading on the skeleton, but data regarding the effects of loading is limited. This study is aimed at examining the effects of loading on the skeleton of the oim mouse model. The oim mouse model produces defective type I collagen, the most abundant structural protein in the body. The oim mouse has a phenotype similar to human type III human osteogenesis imperfecta (OI), including fractures, cortical thinning, and bowing of long bones. Current therapies for OI have been marginally successful and can be painful and invasive with significant recovery times. Data from this study may aid in development of non-invasive treatments via target exercise and muscle training for OI, and other bone diseases such as osteoporosis. This project served as a pilot study to determine if current methods are sensitive enough to detect changes that occur due to muscle loading. Mice were anesthetized and the gastrocnemius muscle removed to impose mechanical overload on the plantaris and soleus muscles. The mice resumed activity for three weeks before being euthanized and the leg bones removed. The bones were subject to microCT to obtain geometric parameters before undergoing torsional loading to failure to assess bone biomechanics. The remaining muscles were examined for histological differences, and their collagen content determined using a hydroxyproline assay. Data thus far confirms that our methodology will detect changes in both muscle and bone, and future work will determine if muscle loading improves bone quality

SU(3) Lattice Gauge Theory With Adjoint Action At Nonzero Temperature

We study the thermal phase diagram of pure SU(3) gauge theory with fundamental and adjoint couplings. We improve previous estimates of the position of the bulk transition line and determine the thermal deconfinement transition lines for $N_t=2,4,6,$ and 8. For $N_t > 4$ the deconfinement transition line splits cleanly away from the bulk transition line. With increasing $N_t$ the thermal deconfinement transition lines shift to increasingly weaker coupling, joining onto the bulk transition line at increasingly larger $\beta_a$ in a pattern consistent with the usual universality picture of lattice gauge theories.Comment: Talk presented by U. M. Heller at Lat94 conference, September 27 - October 1, 1994, Bielefeld, Germany. self unwrapping postscript fil

Heavy-Light Decay Constants with Dynamical Gauge Configurations and Wilson or Improved Valence Quark Action

We describe a calculation of heavy-light decay constants including virtual quark loop effects. We have generated dynamical gauge configurations at three $\beta$ values using two flavors of Kogut-Susskind quarks with a range of masses. These are analyzed with a Wilson valence quark action. Preliminary results based on a ``fat-link'' clover valence quark action are also reported. Results from the two methods differ by 30 to 50 MeV, which is presumably due to significant - but as yet unobserved - lattice spacing dependence in one or both of the approaches.Comment: 3 pages, 1 figure, LeTeX, uses espcrc2, epsf LATTICE99(Heavy Quarks

Exotic hybrid mesons with light quarks

Hybrid mesons, made from a quark, an antiquark and gluons, can have quantum numbers inaccessible to conventional quark-antiquark states. Confirmation of such states would give information on the role of "dynamical" color in low energy QCD. We present preliminary results for hybrid meson masses using light Wilson valence quarks.Comment: 4 pages, 4 figures, Talk presented at LATTICE96(spectrum

Performance Portability Strategies for Grid C++ Expression Templates

One of the key requirements for the Lattice QCD Application Development as part of the US Exascale Computing Project is performance portability across multiple architectures. Using the Grid C++ expression template as a starting point, we report on the progress made with regards to the Grid GPU offloading strategies. We present both the successes and issues encountered in using CUDA, OpenACC and Just-In-Time compilation. Experimentation and performance on GPUs with a SU(3)$\times$SU(3) streaming test will be reported. We will also report on the challenges of using current OpenMP 4.x for GPU offloading in the same code.Comment: 8 pages, 4 figures. Talk presented at the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spai

Spatial Resolution of a Micromegas-TPC Using the Charge Dispersion Signal

The Time Projection Chamber (TPC) for the International Linear Collider will need to measure about 200 track points with a resolution close to 100 $\mu$m. A Micro Pattern Gas Detector (MPGD) readout TPC could achieve the desired resolution with existing techniques using sub-millimeter width pads at the expense of a large increase in the detector cost and complexity. We have recently applied a new MPGD readout concept of charge dispersion to a prototype GEM-TPC and demonstrated the feasibility of achieving good resolution with pads similar in width to the ones used for the proportional wire TPC. The charge dispersion studies were repeated with a Micromegas TPC amplification stage. We present here our first results on the Micromegas-TPC resolution with charge dispersion. The TPC resolution with the Micromegas readout is compared to our earlier GEM results and to the resolution expected from electron statistics and transverse diffusion in a gaseous TPC.Comment: 5 pages, 8 figures, to appar in the Proceedings of the 2005 International Linear Collider Workshop (LCWS05), Stanford, 18-22 March 200