104 research outputs found
Rags make paper
No full textIt's noted as being an a.p. copy.Signed by Richard Bigus and Garner H. Tullis
Running With Ghosts: A Memoir of Surviving Childhood Cancer
No full textIn Running With Ghosts, author Matt Tullis reminds us that surviving childhood cancer can be a challenge as formidable as fighting for your life—and more enduring. The eldest of three sons born to a trucker and an office-worker, who lived in the idyllic village of Apple Creek, Ohio, Tullis was diagnosed with acute lymphoblastic leukemia at age 15. In short order, the sports-mad teenager found himself on the cancer ward of Akron Children’s Hospital. One of the lucky ones, he walked out and kept on going.
Years later, as a journalist and college professor, Tullis began to wonder about all the friends and caregivers he’d left behind on 4-North. As his curiosity intensified, he decided to seek them out. Running With Ghosts is about friendship, loss, triumph, and closure: one man’s effort to understand more fully a life shaped by a random mutation in the code of his DNA.https://digitalcommons.fairfield.edu/english-books/1071/thumbnail.jp
Correction [to “Experimental deformation of dry westerly granite” by Jan Tullis and R. A. Yund]
No full textMineral reaction and deformation in Plagioclase-Olivine composites : an experimental study
No full textDeformation and metamorphism of rocks are fundamentally interrelated but the ways in which processes of reaction and deformation mutually influence each other are still poorly understood in natural rocks. The aim of this thesis is to investigate relationships between plastic deformation and mineral reactions, by means of rock deformation experiments. Within this broad aim, the thesis focuses on (1) the spatial distribution of deformation and reaction during ductile shear, (2) the effect of mineral reactions on the strength, deformation mechanisms and microstructures of dry rocks and (3) the effect of ductile shear deformation on kinetics and mechanisms of a dry net-transfer reaction. To these ends, water-deficient plagioclase-olivine composites were studied after shear deformation and hydrostatic experiments inside and outside their chemical stability fields, using a Griggs apparatus. Experiments were performed on anorthite-forsterite (An92 -Fo93 ) and labradorite-forsterite (An60 -Fo93 ) composites at 900◦ C, confining pressures between 1000-1600 MPa and with constant shear strain rates of γ ∼5x10−5 s−1 . ˙ The hydrostatic and deformed samples were examined by backscattered scanning electron microscopy (BSEM) and transmission electron microscopy (TEM). At all chosen confining pressures, stable labradorite-olivine composites are found to strain-harden during shear deformation, up to stresses close to the brittle-plastic transition (τ ∼500-780 MPa). Pure olivine and labradorite samples are less strong (τ ∼350 and 100 MPa, respectively) than the labradorite-olivine composites. The pure olivine sample displayed low temperature plasticity, accompanied by some dynamic recrystallisation. The hardening of the labradorite-olivine composites is probably due to the inhibition of grain boundary migration by inter-phase boundaries, which prevent recovery. The prevention of recovery results in labradorite and olivine grains with local high dislocation densities. At all chosen confining pressures, concurrent plastic deformation and reaction of metastable anorthite-olivine composites results in a pronounced decrease in shear stress (τ ∼150 MPa). The onset of weakening coincides with the formation of fine-grained polyphase reaction products (size ∼0.25-1.0 µm). The onset of steady-state flow (γ >5, τ ∼200 MPa) is characterised by the coalescence of these products into interconnecting layers. The fine-grained reaction products deform by grain size sensitive creep. Fabric analysis using the autocorrelation function shows a strong correlation on a sample scale between reaction progress and strain; large shear strain is locally associated with high reaction progress. On a grain scale the applied strain is localised and accommodated in the interconnecting layers of reaction products. Strain accommodation in reaction product layers reduces the strain rate in the reacting anorthite and
olivine grains, which, as a result, are able to undergo recovery by dislocation climb.
The reaction weakening mechanism in anorthite-olivine composites is grain size reduction
by crystallisation of fine-grained polyphase reaction products, which deform
by diffusion-accommodated grain boundary sliding. The reaction causes a change in
deformation mechanism from grain size insensitive creep of the anorthite-olivine composite
to grain size sensitive creep of reaction products. The measured reduction of
shear stress at a constant strain rate confirms this change in the dominant deformation
mechanism of the samples.
The growth rates of enstatite and pyroxene-spinel-garnet reaction rims observed
around olivine and plagioclase indicate that reaction at hydrostatic and water-deficient
conditions is controlled by the limited transport of chemical components. The amount
of pressure overstepping in the experiments affects the reaction progress because the
rate of nucleation increases exponentially with the Gibbs free energy of reaction (the
amount of pressure overstepping for pressure-sensitive reactions). Nevertheless, the
studied reactions display a delayed onset of nucleation of new phases (30 to �80 hrs),
even at pressure overstepping of 700 to 900 MPa.
The plastic deformation of anorthite-olivine composites was found to enhance the
studied mineral reactions at water-deficient conditions. This enhancement is shown by
the increase of reaction progress as well as the increase of the nucleation and growth
rates of reaction rims during deformation. The reaction between anorthite and olivine is
enhanced by an increase in the nucleation rate of new phases. The increased nucleation
rate may be due to high dislocation densities in the reactant grains that deform by
low-temperature plasticity. The mechanical transport of reaction products by grain
boundary sliding may change the local equilibrium conditions, which, in combination
with slow diffusion and fast nucleation, results in the formation of metastable kyanite.
In summary, this experimental study shows that concurrent plastic deformation
and reaction processes in plagioclase-olivine composites positively influence each other:
rheological weakening may result from mineral reactions, and the localisation of reaction
progress in shear zones can be enhanced by plastic deformation. The results of this
thesis imply that concurrent deformation and reaction at water-deficient conditions are
of major importance in explaining how and why strain localisation occurs in polyphase
rocks under a large range of geological conditions
Reply [to “Comment on ‘The effects of pressure and porosity on the micromechanics of the brittle‐ductile transition in quartzite’ by Greg Hirth and Jan Tullis”]
No full textA Search for Place: Eight Generations of Henrys and the Settlement of Utah\u27s Uintah Basin
No full textLaMond Tullis, emeritus professor of political science at Brigham Young University and author of Mormons in Mexico and Lord and Peasant in Peru, among other works, tries in his latest book to put his ancestors in their rightful place. He tells the story of the Henrys, from the Scotch-Irish John Henry who settled in Rhode Island in the late 1600s down to the generation of his mother\u27s family, who settled in the Uintah Basin. Migrating from New England through New York to the Midwest and the Rocky Mountains, these westering Henrys are placed by Tullis into larger contexts, their stories woven into and symbolic of American life. The experiences of these migratory risk takers in the Uintah Basin of Utah clarify what it cost to settle in that stern and exacting locale.
As the title indicates, these ancestors are also studies in the human need and hope to find a place of their own. Tullis broadly defines this sense of place as the merging of a person\u27s internal and external landscapes, a situation where they feel right. The place framework is also enlightening in a story with so much movement. The term is loaded with enough meaning in the prologue to make the reader pause to consider how it is used when encountered, as it frequently is, in the text
Weakening and strain localization produced by syn-deformational reaction of plagioclase
No full textThere are many observations in naturally deformed rocks on the effects of mineral reactions on deformation, but few experimental data. In order to study the effects of chemical disequilibrium on deformation we have investigated the hydration reaction plagioclase + H2O→ more albitic plagioclase + zoisite + kyanite + quartz. We utilized fine-grained (2–6 µm) plagioclase aggregates of two compositions (An54 and An60), both dried and with 0.1–0.4 wt% H2O present, in shear deformation experiments at two sets of conditions: 900 °C, 1.0 GPa (in the plagioclase stability field) and 750 °C, 1.5 GPa (in the zoisite stability field). Dry samples and those deformed in the plagioclase stability field underwent homogeneous shearing by dislocation creep, but samples with 0.1 to 0.4 wt% water deformed in the zoisite stability field showed extreme strain localization into very narrow (~1–3 µm) shear bands after low shear strain. In these samples the microstructures of reaction products in the matrix differ from those in the shear bands. In the matrix, large (up to 400 µm) zoisite crystals grew in the direction of finite extension, and relict plagioclase grains are surrounded by rims of recrystallized grains that are more albitic. In the shear bands, the reaction products albitic plagioclase, zoisite, white mica, and traces of kyanite form polyphase aggregates of very fine-grained (<0.1 µm) dislocation-free grains. Most of the sample strain after γ ~2 has occurred within the shear bands, within which the dominant deformation mechanism is inferred to be diffusion-accommodated grain boundary sliding (DAGBS). The switch from dislocation creep in dry samples deformed without reaction to DAGBS in reacted samples is associated with a decrease in flow stress from ~800 to <200 MPa. These experiments demonstrate that heterogeneous nucleation driven in part by chemical disequilibrium can produce an extremely fine-grained polyphase assemblage, leading to a switch in deformation mechanism and significant weakening. Thus, localization of deformation in polyphase rocks may occur on any pressure (P),temperature (T)-path where the equilibrium composition of the constituent minerals changes
Uintah Flag Twirlers
No full textUintah Flag Twirlers to perform at SUSU. From left are, front row, Trini Ben, Lori Black, Jan Williams. Back row, Delsi Moore, Amber Tullis and Ellen Larsen
The effect of water, temperature and strain rate on the dislocation creep microstructure, recystallized
No full textSince the work of Griggs & Blacic (1965)
it is well known that the crystal plastic
flow strength of ‘wet’ quartz samples is
much lower than that of ‘dry’ samples
deformed at the same conditions, and
the general effect of water on dislocation
creep microstructures has been documented
(e.g. Hirth & Tullis 1992), but
its effect on the recrystallized grain size
has not been quantified. The recrystallized
grain size is the most reliable and
most easily measurable microstructural
feature to derive flow stresses from natural
mylonites (e.g. White 1979, Kohlstedt
et al. 1980). In a recent experimental
study, a well-constrained recrystallized
grain size piezometer for quartz
(Stipp & Tullis 2003) was calibrated
using natural as-is quartzites; the use
of a molten salt cell at high confining
pressure (1.5GPa) in a Griggs-type apparatus
allowed good stress resolution
(Green & Borch 1989). There has been
some debate as to whether there is any
independent effect of water on the recrystallized
grain size piezometer. Two
laboratory studies on olivine aggregates
(at different pressures) report contradictory
results; van der Wal et al. (1993)
found that the recrystallized grain size
piezometer is independent of the water
content, whereas Jung & Karato
(2001) observed a water-dependence of
the piezometer.
In this study, we have investigated
changes in the recrystallized grain
size and other deformation microstructures
of quartz within dislocation creep
regimes 2 and 3 of Hirth & Tullis
(1992). Deformation experiments on
Black Hills quartzite with three different
initial water contents (as-is, wateradded
and vacuum-dried) were carried
out in order to evaluate the effect of
water on the recrystallized grain size /
flow stress piezometer...conferenc
County Fair Dog Show
No full textUintah County Fair 4-H dog show winners are fom left, Jan Williams with Taffy, Amber Tullis with Snoopy, Ann Huffaker with Sue, Collette Sweatfield with Rowdy and Joyce Reynolds with Kim
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