1,131 research outputs found

    The Mark of Rebels: Indios Fronterizos and Mexican Independence. Barry M. Robinson. Tuscaloosa, AL: University of Alabama Press, 2016. 191 pp.

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148231/1/jlca12394.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148231/2/jlca12394_am.pd

    Quantum Theory of Complex Ultracold Collisions

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    This thesis reports on a variety of calculations on cold and ultracold scattering, with a broad theme of how best to consider and understand complex systems in simple ways. Firstly, we investigate quantum defect theory. We demonstrate that it is not only an excellent model for simple systems, but can also provide simple predictions of the \emph{range} of possible behaviours for complex systems, in particular for a model of collisional losses. These predictions agree well with expensive coupled-channels calculations in cases where the full calculations also predict only the range of possible behaviours. Secondly, we consider effects relating to thermalisation of cold and ultracold gases. We show that considering the correct transport cross section, ση(1)\sigma_\eta^{(1)}, is important for determination of scattering lengths and their signs by interspecies thermalisation. This cross section is also important to the understanding of high-quality simulations of sympathetic cooling in a microwave trap, which suggest Rb is likely to be a good coolant for CaF. We also correct an error in the interpretation of previous results for sympathetic cooling in a magnetic trap, showing this may work from over 100 mK for Li+CaF and many Kelvin when using atomic hydrogen as a coolant. Thirdly, we study quantum chaos in ultracold collisions. We find very clear and strong signs of chaos in Li+CaH. We also show that a more strongly coupled system, Li+CaF, is \emph{not} fully chaotic and that there is unexpected structure in the levels of chaos as the CaF rotational constant is varied. We also show that signatures of chaos can emerge in a very simple atom-atom system, Yb(1S0{}^1S_0)+Yb(3P2{}^3P_2), which interacts on only two Born-Oppenheimer potentials. Finally, we examine the idea that metastable states in 2-body scattering greatly enhance 3-body recombination at ultracold temperatures. We attempt to put it on a more rigorous theoretical grounding by considering Smith's collision lifetime and related quantities, but those are shown to lack clear interpretations in the ultracold regime. We therefore consider 3-body scattering theory and arrive at some general conclusions about how we expect such 2-body features to appear in 3-body scattering and suggest possible ways forward

    A Sub-Damped Lyα\alpha Absorber with Unusual Abundances: Evidence of Gas Recycling in a Low-Redshift Galaxy Group

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    Using Hubble Space Telescope/Space Telescope Imaging Spectrograph G140M spectroscopy, we investigate an absorption-line system at zz=0.07489 in the spectrum of the quasi-stellar object PG 1543+489 (zQSOz_{QSO}=0.401). The sightline passes within ρ=66\rho = 66 kpc of an edge-on 2L2L^* disk galaxy at a similar redshift, but the galaxy belongs to a group with four other galaxies within ρ=160\rho =160 kpc. We detect H I [log NN(H I/cm2cm^{-2}) = 19.12±\pm0.04] as well as N I, Mg II, Si II, and Si III, from which we measure a gas-phase abundance of [N/H] = 1.0±0.1-1.0\pm 0.1. Photoionization models indicate that the nitrogen-to-silicon relative abundance is solar, yet magnesium is underabundant by a factor of \approx 2. We also report spatially resolved emission-line spectroscopy of the nearby galaxy, and we extract its rotation curve. The galaxy's metallicity is 8×\approx 8 \times higher than [N/H] in the absorber, and interestingly, the absorber velocities suggest that the gas at ρ=\rho = 66 kpc is corotating with the galaxy's stellar disk, possibly with an inflow component. These characteristics could indicate that this sub-damped Lyα\alpha absorber system arises in a "cold-accretion" flow. However, the absorber abundance patterns are peculiar. We hypothesize that the gas was ejected from its galaxy of origin (or perhaps is a result of tidal debris from interactions between the group galaxies) with a solar nitrogen abundance, but that subsequently mixed with (and was diluted by) gas in the circumgalactic medium (CGM) or group. If the gas is bound to the nearby galaxy, this system may be an example of the gas "recycling" predicted by theoretical galaxy simulations. Our hypothesis is testable with future observations.Comment: 16 pages (in print): The Astrophysical Journal, vol 872, 12

    Fitting the Means to the Ends: One School’s Experience with Quantitative and Qualitative Methods in Curriculum Evaluation During Curriculum Change

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    Curriculum evaluation plays an important role in substantive curriculum change. The experience of the University of Texas Medical Branch (UTMB) with evaluation processes developed for the new Integrated Medical Curriculum (IMC) illustrates how evaluation methods may be chosen to match the goals of the curriculum evaluation process. Quantitative data such as ratings of courses or scores on external exams are useful for comparing courses or assessing whether standards have been met. Qualitative data such as students’ comments about aspects of courses are useful for eliciting explanations of observed phenomena and describing relationships between curriculum features and outcomes. The curriculum evaluation process designed for the IMC used both types of evaluation methods in a complementary fashion. Quantitative and qualitative methods have been used for formative evaluation of the new IMC courses. They are now being incorporated into processes to judge the IMC against its goals and objectives

    Observations of the Gas Reservoir around a Star Forming Galaxy in the Early Universe

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    We present a high signal-to-noise spectrum of a bright galaxy at z = 4.9 in 14 h of integration on VLT FORS2. This galaxy is extremely bright, i_850 = 23.10 +/- 0.01, and is strongly-lensed by the foreground massive galaxy cluster Abell 1689 (z=0.18). Stellar continuum is seen longward of the Ly-alpha emission line at ~7100 \AA, while intergalactic H I produces strong absorption shortward of Ly-alpha. Two transmission spikes at ~6800 Angstroms (A) and ~7040 A are also visible, along with other structures at shorter wavelengths. Although fainter than a QSO, the absence of a strong central ultraviolet flux source in this star forming galaxy enables a measurement of the H I flux transmission in the intergalactic medium (IGM) in the vicinity of a high redshift object. We find that the effective H I optical depth of the IGM is remarkably high within a large 14 Mpc (physical) region surrounding the galaxy compared to that seen towards QSOs at similar redshifts. Evidently, this high-redshift galaxy is located in a region of space where the amount of H I is much larger than that seen at similar epochs in the diffuse IGM. We argue that observations of high-redshift galaxies like this one provide unique insights on the nascent stages of baryonic large-scale structures that evolve into the filamentary cosmic web of galaxies and clusters of galaxies observed in the present universe.Comment: Accepted for publication in ApJL (corrected typos

    Research into chemical separation techniques for production of Bi-213 via irradiation of Ra-226 [abstract]

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    Abstract only availableBismuth 213 is an alpha radioimmunotherapeutic agent used in cancer treatment. Neutron bombardment of radium 226 is being investigated as an alternative method of producing Bi-213. For this project, a literature search of existing chemical separation steps for the production of Bis-213 for radioimmunotherapy was performed in order to optimize the combination of irradiation schemes with chemical separation steps. For the first step, the separation of actinium and radium from thorium 229 and recovery of radium for further irradiation, several successful methods were described in the literature. Organic cation exchange columns such as AG50W-X8 have traditionally been used to perform this step, but these suffer high radiolysis, which newer methods have tried to address. Some of these are an extraction chromatography method using a UTEVA column followed by a RE-resin column on a silica gel support, an inorganic titanium phosphate ion exchanger, and sublimation of the anhydrous chlorides of Th-229 and its daughter isotopes performed in a quartz tube, featuring complete separation of the elements while radium is retained at the bottom of the tube and available for further irradiation in one step. For the second part of the process, the elution of Bis-213 from an Ac-225 generator, quite a few successful techniques are described in the literature. Some of the better ones found are a multicolumn selectivity inversion generator, a renewable column, tandem column extraction chromatography, a PNNL automated generator, a MSKCC generator, an inorganic hydrated zirconium cation exchanger, and silica based resins, as well as the more traditional organic cation and anion exchange columns. A method using alpha recoil of Bis-213 from Ac-225 incorporated into a sealed isotope generator has the benefit of resulting in no radioactive, chemical, or mixed wastes, in contrast to chemical separation methods. In conclusion, several promising separation techniques were found in the literature

    Soil Erosion with Different Tillage and Cropping Systems

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    Corn and soybeans are produced on approximately three million acres of Kentucky farmland each year. L 1ttle soil loss occurs when these crops are grown on nearly level or gently sloping land. However, much of the grain production is on sloping land that is cultivated every year and often excessive soil erosion occurs. If a field is allowed to erode excessively for several years, the soil usually becomes less productive. Soil removed in runoff may pollute lakes and streams or cover highly productive soil with low quality sediments

    1988 Convocation

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    Opening Selections: First Class Brass, George Frederich Handel Processional: Jean Joseph Mouret Welcome: Dr. Leon Lederman, Director, Fermi Laboratory, Vice President Board of Trustees; Dr. Stephanie Pace Marshall, Director; David Kung, Student Council President Introductions: Dr. Stephanie Pace Marshall, Director Musical Selection: Franz Von Suppe Keynote Speaker: Dr. Donald Frye, Former Chief Executive Bell & Howell Co., Professor of Industrial Engineering and Management Science, Northwestern University Recessional: George Frederich Hande

    Phytochemistry Predicts Habitat Selection by an Avian Herbivore at Multiple Spatial Scales

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    Animal habitat selection is a process that functions at multiple, hierarchically structured spatial scales. Thus multi-scale analyses should be the basis for inferences about factors driving the habitat selection process. Vertebrate herbivores forage selectively on the basis of phytochemistry, but few studies have investigated the influence of selective foraging (i.e., fine-scale habitat selection) on habitat selection at larger scales. We tested the hypothesis that phytochemistry is integral to the habitat selection process for vertebrate herbivores. We predicted that habitats selected at three spatial scales would be characterized by higher nutrient concentrations and lower concentrations of plant secondary metabolites (PSMs) than unused habitats. We used the Greater Sage-Grouse (Centrocercus urophasianus), an avian herbivore with a seasonally specialized diet of sagebrush, to test our hypothesis. Sage-Grouse selected a habitat type (black sagebrush, Artemisia nova) with lower PSM concentrations than the alternative (Wyoming big sagebrush, A. tridentata wyomingensis). Within black sagebrush habitat, Sage-Grouse selected patches and individual plants within those patches that were higher in nutrient concentrations and lower in PSM concentrations than those not used. Our results provide the first evidence for multi-scale habitat selection by an avian herbivore on the basis of phytochemistry, and they suggest that phytochemistry may be a fundamental driver of habitat selection for vertebrate herbivores

    Crisis Decision-Making During Hurricane Sandy: An Analysis of Established and Emergent Disaster Response Behaviors in the New York Metro Area

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    Objective This collective case study examined how and why specific organizational decision-making processes transpired at 2 large suburban county health departments in lower New York State during their response to Hurricane Sandy in 2012. The study also examined the relationships that the agencies developed with other emerging and established organizations within their respective health systems. Methods In investigating these themes, the authors conducted in-depth, one-on-one interviews with 30 senior-level public health staff and first responders; reviewed documentation; and moderated 2 focus group discussions with 17 participants. Results Although a natural hazard such as a hurricane was not an unexpected event for these health departments, they nevertheless confronted a number of unforeseen challenges during the response phase: prolonged loss of power and fuel, limited situational awareness of the depth and breadth of the storm’s impact among disaster-exposed populations, and coordination problems with a number of organizations that emerged in response to the disaster. Conclusions Public health staff had few plans or protocols to guide them and often found themselves improvising and problem-solving with new organizations in the context of an overburdened health care system
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