Polarization and Structure of Broad Absorption Line Quasi-Stellar Objects

This thesis is a spectropolarimetric survey of broad absorption line quasi-stellar objects (BAL QSO). We observed 36 BAL QSO at low resolution with the 5 m Hale Telescope at Palomar Observatory and the 10 m Keck Telescopes at the W. M. Keck Observatory. The continuum, absorption trough, and emission line polarization of BAL QSO were studied in detail, yielding clues about the geometrical structure of gas in the inner regions of quasars. BAL QSO have, on average, higher polarization than other quasars, reinforcing the view that they are normal quasars viewed from a more equatorial aspect. However, there is a wide distribution of polarization values, which may be due to intrinsic differences in the geometry or optical depth to scattering. No correlations are found among emission line or broad absorption line properties and continuum polarization, suggesting that these properties are regulated by internal differences unrelated to viewing angle. The continuum polarization of BAL QSO is weakly wavelength dependent after correction for emission line dilution. In most objects, the polarization rises to the blue, suggesting that dust scattering or absorption may be important. Broad emission line photons are polarized less than the continuum; and the position angle of the electric vector is rotated with respect to the continuum. The semi-forbidden C III] emission line is polarized differently than the C IV emission line in some cases, suggesting resonance scattering in the C III] emission line region. Resonantly scattered photons from the broad absorption line region are detected at high velocities red-ward and blue-ward of the C IV line center in the spectra of some objects. These photons are negatively polarized with respect to the continuum photons, showing that the broad absorption line region and the continuum scattering region are oriented perpendicular to each other. The polarization increases in the BAL troughs, due mainly to partial coverage of the central source by the broad absorption line region. Partial coverage of the continuum and broad emission line clouds leads to difficulties in determining the true optical depth of the BAL outflow. The geometry of the intervening BAL clouds is skewed with respect to the continuum scattering region, which results in position angle rotations in the BAL. The variation of polarization with velocity in the BAL is consistent with a non-radial, accelerating outflow of ionized gas. Our polarimetry observations are consistent with a model which unifies BAL QSO and non-BAL QSO. The BAL wind appears to occupy a narrow range of equatorial latitudes. When we view a QSO through this outflow, we see the characteristic troughs in BAL QSO.</p

Quantification of the Thermal Hazard from Metallic and Organic Dust Flash Fires

PresentationAn in-house constructed nominally 20-L flash fire apparatus was used to evaluate and compare the flash fires fueled by an organic dust (non-dairy coffee creamer) a metal dust (aluminum) and a flammable gas (methane). Dispersion was achieved using an injection system similar to the injection systems found in standard Siwek 20-L combustion chambers and a 10-J spark igniter was used to ignite the fuels. A heat flux gauge, thermocouples, an Infrared video camera, and an HD video camera were all used to evaluate the severity of the flash fires. Multiple concentrations of dusts and a stoichiometric methane mixture were tested. All measurement methods showed reasonable agreement when ranking the severity of different deflagrations, but thermocouple and heat flux gauge measurements were sensitive to the position of the flame, leading to some inconsistency. IR video measurements provided fireball dimensions and growth rates, and relative temperatures for dust-fueled deflagration, but were unable to accurately assess the high-turbulence premixed methane flash fires due to the high burning velocities and 30 frames per second limitation. The IR camera was also limited to 1200o C, which is inadequate for the temperature of some metal dust deflagrations, including aluminum and requires adjustment of the material emissivity, which would require additional analysis and testing. Measurement strategies for a next-generation flash fire testing apparatus are proposed based on the results of this study

Preferential Lineage-Specific Differentiation of Osteoblast-Derived Induced Pluripotent Stem Cells into Osteoprogenitors

While induced pluripotent stem cells (iPSCs) hold great clinical promise, one hurdle that remains is the existence of a parental germ-layer memory in reprogrammed cells leading to preferential differentiation fates. While it is problematic for generating cells vastly different from the reprogrammed cells\u27 origins, it could be advantageous for the reliable generation of germ-layer specific cell types for future therapeutic use. Here we use human osteoblast-derived iPSCs (hOB-iPSCs) to generate induced osteoprogenitors (iOPs). Osteoblasts were successfully reprogrammed and demonstrated by endogenous upregulation of Oct4, Sox2, Nanog, TRA-1-81, TRA-16-1, SSEA3, and confirmatory hPSC Scorecard Algorithmic Assessment. The hOB-iPSCs formed embryoid bodies with cells of ectoderm and mesoderm but have low capacity to form endodermal cells. Differentiation into osteoprogenitors occurred within only 2-6 days, with a population doubling rate of less than 24 hrs; however, hOB-iPSC derived osteoprogenitors were only able to form osteogenic and chondrogenic cells but not adipogenic cells. Consistent with this, hOB-iOPs were found to have higher methylation of PPAR gamma but similar levels of methylation on the RUNX2 promoter. These data demonstrate that iPSCs can be generated from human osteoblasts, but variant methylation patterns affect their differentiation capacities. Therefore, epigenetic memory can be exploited for efficient generation of clinically relevant quantities of osteoprogenitor cells

Hematology, plasma biochemistry, and hormonal analysis of captive Louisiana pine snakes (Pituophis ruthveni): effects of intrinsic factors and analytical methodology

Blood analyte data are useful in health assessments and management of reptiles. There is a knowledge gap for blood analyte data of the endangered Louisiana pine snake (LPS; Pituophis ruthveni). The objectives of this study were to provide baseline hematology, plasma biochemical, and hormone data of captive LPS, to compare the data in juvenile and adult snakes and in adult snakes by sex, and to investigate methodological differences in hormone (serum vs. plasma) and protein analyses (total solids versus total protein). Blood samples from apparently healthy captive LPS were analyzed for hematology and plasma biochemistry (n = 11) and plasma and serum hormone analyses (n = 9). Packed cell volume (PCV) and absolute heterophils were significantly higher in adult compared with juvenile LPS, while PCV, white blood cell count, and absolute lymphocytes were higher in adult males compared with adult females. Significantly higher plasma concentrations were found in adults compared with juveniles for calcium, total protein, total solids, albumin, globulins, and bile acids. No significant differences were observed in 17β-estradiol measured in serum and plasma when comparing adults and juveniles and for 17β-estradiol in adult males and females. Plasma concentrations of 17β-estradiol were significantly lower than in serum. Serum testosterone in two adult males was 8.33 and 35.53 nmol/L, respectively, while it was undetectable in females and juveniles (n = 5). This study is the first to provide baseline information on blood analytes in endangered LPS, which will be useful for individual animals in managed care and as baseline for future population-level assessments

Enhanced Osseous Integration of Human Trabecular Allografts Following Surface Modification With Bioactive Lipids

In this study, we used extracellular matrix (ECM) gels and human bone allograft as matrix vehicles to deliver the sphingolipid growth factor FTY720 to rodent models of tibial fracture and a critical-sized cranial defect. We show that FTY720 released from injectable ECM gels may accelerate callous formation and resolution and bone volume in a mouse tibial fracture model. We then show that FTY720 binds directly to human trabecular allograft bone and releases over 1 week in vitro. Rat critical-sized cranial defects treated with FTY720-coated grafts show increases in vascularization and bone deposition, with histological and micro-computed topography (microCT) evidence of enhanced bone formation within the graft and defect void. Immunohistochemical analysis suggests that osteogenesis within FTY720-coated grafts is associated with reduced CD68(+) macrophage infiltration and recruitment of CD29(+) bone progenitor cells. Matrix binding of FTY720 thus represents a promising and robust bone regeneration strategy with potential clinical translatability

Pseudomonas aeruginosa cross-colonization and persistence in patients with cystic fibrosis. Use of a DNA probe

To investigate cross-colonization with and persistence of Pseudomonas aeruginosa in cystic fibrosis (CF). 181 isolates from 76 CF patients were typed using a P. aeruginosa -specific DNA probe. Whereas sibling pairs predominantly harboured genotypically identical P. aeruginosa strains, all of the other patients harboured different strains. Seventy-nine per cent (22/31) of the infected CF patients harboured the same strains at the beginning and the end of a summer camp. A change of strains was seen in 10% (3/31) of the patients at the end of the camp. Forty-six per cent (6/13) of the patients who were apparently initially uninfected, acquired P. aeruginosa by the end of the period. Genotyping proved that strain change or acquisition was due to cross-colonization in four of nine cases. Very little P. aeruginosa was isolated from the inanimate environment. Persistence of P. aeruginosa after a temporary loss due to antibiotic therapy was seen in 12/16 paired patient strains before and after antibiotic therapy. Thus, suppression followed a flare-up seemed to occur in these patients rather than eradication and a new infection. When 35 patients were followed over a period of 6 months, 7 (20%) changed the strain in their sputum. Only one of 43 patients harboured two different P. aeruginosa strains simultaneously over a long perio

A hierarchical, multivariate meta-analysis approach to synthesising global change experiments

Meta-analyses enable synthesis of results from globally distributed experiments to draw general conclusions about the impacts of global change factors on ecosystem function. Traditional meta-analyses, however, are challenged by the complexity and diversity of experimental results. We illustrate how several key issues can be addressed via a multivariate, hierarchical Bayesian meta-analysis (MHBM) approach applied to information extracted from published studies. We applied an MHBM to log-response ratios for aboveground biomass (AB, n = 300), belowground biomass (BB, n = 205), and soil CO2 exchange (SCE, n = 544), representing 100 studies. The MHBM accounted for study duration, climate effects, and covariation among the AB, BB, and SCE responses to elevated CO2 (eCO2) and/or warming. The MHBM revealed significant among-study covariation in the AB and BB responses to experimental treatments. The MHBM imputed missing duration (4.2%) and climate (6%) data, and revealed that climate context governs how eCO2 and warming impact ecosystem function. Predictions identified biomes that may be particularly sensitive to eCO2 or warming, but that are under-represented in global change experiments. The MHBM approach offers a flexible and powerful tool for synthesizing disparate experimental results reported across multiple studies, sites, and response variables

Intrinsic Absorption in the Spectrum of NGC 7469: Simultaneous Chandra, FUSE, and STIS Observations

We present simultaneous X-ray, far-ultraviolet, and near-ultraviolet spectra of the Seyfert 1 galaxy NGC 7469 obtained with the Chandra X-Ray Observatory, the Far Ultraviolet Spectroscopic Explorer, and the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. Previous non-simultaneous observations of this galaxy found two distinct UV absorption components, at -560 and -1900 km/s, with the former as the likely counterpart of the X-ray absorber. We confirm these two absorption components in our new UV observations, in which we detect prominent O VI, Ly alpha, N V, and C IV absorption. In our Chandra spectrum we detect O VIII emission, but no significant O VIII or O VII absorption. We also detect a prominent Fe K alpha emission line in the Chandra spectrum, as well as absorption due to hydrogen-like and helium-like neon, magnesium, and silicon at velocities consistent with the -560 km/s UV absorber. The FUSE and STIS data reveal that the H I and C IV column densities in this UV- and X-ray- absorbing component have increased over time, as the UV continuum flux decreased. We use measured H I, N V, C IV, and O VI column densities to model the photoionization state of both absorbers self-consistently. We confirm the general physical picture of the outflow in which the low velocity component is a highly ionized, high density absorber with a total column density of 10^20 cm^-2, located near the broad emission line region, although due to measurable columns of N V and C IV, we assign it a somewhat smaller ionization parameter than found previously, U~1. The high velocity UV component is of lower density, log N=18.6, and likely resides farther from the central engine as we find its ionization parameter to be U=0.08.Comment: Minor correction to abstract; STScI eprint #1683; 50 pages, incl. 19 figures, 4 tables; Accepted to Ap