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Modification and control of the interface of high temperature cuprate superconductors using self-assembled monolayers
textHigh temperature superconductors are plagued by numerous material
problems that have hampered the commercial development of these complex
copper oxides. One of the most problematic material characteristics is the
propensity of the cuprates to undergo reduction in the presence of water, acids,
CO and CO2. One of the solutions to prevent corrosion developed in the
McDevitt lab entails protecting the material with a monolayer coating of alkylamine
reagents. While previous work has shown that these monolayers hinder the
corrosion of cuprate superconductors, the mechanism and energetics of the
formation process is poorly understood. The goal of this dissertation is to
examine the mechanism and kinetics of formation of self-assembled amine
monolayers atop cuprate superconductors.
This dissertation is organized as follows: In Chapter 1, the theory of the
materials and thin film deposition processes used in this dissertation are
described. The specifics of the methods and materials employed are described
Chapter 2. In order to examine these phenomena, a new pulsed laser deposition
system capable of generating larger quantities of corrosion free thin film
superconductors has been built and optimized as described in Chapter 3. In
Chapter 4, experimental evidence for the removal of previously exposed corroded
material by the alkyl-amine monolayer reagent has been provided using x-ray
photoelectron spectroscopy, atomic absorption spectroscopy, and scanning
electron micrography. Evidence of the alkyl-amines role in planarizing the
superconductors is also provided. Finally, in Chapter 5, the kinetics of adsorption
have been examined using a redox active monolayer reagent, providing the first
documentation of adsorption isotherms atop cuprate thin films.Chemistry and BiochemistryChemistr
Best Practices for Controlling Tuberculosis - Training in Correctional Facilities: A Mixed Methods Evaluation
According to the literature, identifying and treating tuberculosis (TB) in correctional facilities have been problematic for the inmates and also for the communities into which inmates are released. The importance of training those who can identify this disease early into incarceration is vital to halt the transmission. Although some training has been done by public health authorities for corrections, there is little to no evaluation of such training. The aim of this mixed methods retrospective study was to evaluate the effectiveness of a training to control TB in correctional facilities. The Southeastern National Tuberculosis Center (SNTC) conducted 12 trainings between 2010 and 2014 with custody, medical, and public health staff working in correctional facilities, as well as with TB program staff from health departments. A total of 442 participants quantitatively and qualitatively evaluated the trainings. Gagne-Briggs and tripod models comprised the theoretical framework of the study. Quantitative data were analyzed using descriptive statistics and qualitative data were analyzed thematically. Analysis showed that the usefulness of the training was considered very good to excellent in each of the trainings. Also, many participants stated that they were going to educate others as well, in order to improve the management of TB in their facilities. The results of this study revealed that using systematic training can contribute to promote a more coordinated release of TB-infected inmates into the community, and therefore improve the quality of life of this population group, resulting in the promotion of social change
Overexpression of Sox11 Promotes Corticospinal Tract Regeneration after Spinal Injury While Interfering with Functional Recovery
Embryonic neurons, peripheral neurons, and CNS neurons in zebrafish respond to axon injury by initiating pro-regenerative transcriptional programs that enable axons to extend, locate appropriate targets, and ultimately contribute to behavioral recovery. In contrast, many long-distance projection neurons in the adult mammalian CNS, notably corticospinal tract (CST) neurons, display a much lower regenerative capacity. To promote CNS repair, a long-standing goal has been to activate pro-regenerative mechanisms that are normally missing from injured CNS neurons. Sox11 is a transcription factor whose expression is common to a many types of regenerating neurons, but it is unknown whether suboptimal Sox11 expression contributes to low regenerative capacity in the adult mammalian CNS. Here we show in adult mice that dorsal root ganglion neurons (DRGs) and CST neurons fail to upregulate Sox11 after spinal axon injury. Furthermore, forced viral expression of Sox11 reduces axonal dieback of DRG axons, and promotes CST sprouting and regenerative axon growth in both acute and chronic injury paradigms. In tests of forelimb dexterity, however, Sox11 overexpression in the cortex caused a modest but consistent behavioral impairment. These data identify Sox11 as a key transcription factor that can confer an elevated innate regenerative capacity to CNS neurons. The results also demonstrate an unexpected dissociation between axon growth and behavioral outcome, highlighting the need for additional strategies to optimize the functional output of stimulated neurons
The Nature of the UV/X-Ray Absorber in PG 2302+029
We present Chandra X-ray observations of the radio-quiet QSO PG 2302+029.
This quasar has a rare system of ultra-high velocity (-56,000 km/s) UV
absorption lines that form in an outflow from the active nucleus (Jannuzi et
al. 2003). The Chandra data indicate that soft X-ray absorption is also
present. We perform a joint UV and X-ray analysis, using photoionization
calculations, to detemine the nature of the absorbing gas. The UV and X-ray
datasets were not obtained simultaneously. Nonetheless, our analysis suggests
that the X-ray absorption occurs at high velocities in the same general region
as the UV absorber. There are not enough constraints to rule out multi-zone
models. In fact, the distinct broad and narrow UV line profiles clearly
indicate that multiple zones are present. Our preferred estimates of the
ionization and total column density in the X-ray absorber (log U=1.6,
N_H=10^22.4 cm^-2) over predict the O VI 1032, 1038 absorption unless the X-ray
absorber is also outflowing at ~56,000 km/s, but they over predict the Ne VIII
770, 780 absorption at all velocities. If we assume that the X-ray absorbing
gas is outflowing at the same velocity of the UV-absorbing wind and that the
wind is radiatively accelerated, then the outflow must be launched at a radius
of < 10^15 cm from the central continuum source. The smallness of this radius
casts doubts on the assumption of radiative acceleration.Comment: Accepted for Publication in Ap
'They're battle scars, I wear them well': A phenomenological exploration of young women's experiences of building resilience following adversity in adolescence
This is an Author's Accepted Manuscript of an article published in Journal of Youth Studies, 13(3), 273 - 290, 2010 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/13676260903520886.This phenomenological study explored young women's accounts of building resilience following chains of adverse life experiences in adolescence. Six participants were interviewed, aged 20–25 years. Most had, or were receiving, a university education. They described their recovery from adversity as starting with certain pivotal moments, followed by both short-term and longer-term strategies. Short-term strategies tended to offer respite from distress and emotional comfort, increased clarity about their experiences and social affirmation. Recovery involved gaining new perspectives on their adverse situation and recovering a positive self-image through three longer-term strategies. These involved making visible progress in their education, rebuilding relationships with family and friends, and participating in the ‘normalizing’ activities and developmental projects of adolescence. Participants believed that they were stronger and more compassionate although positive achievements co-existed with some regrets. Most perceived the adversity as catalyzing personal growth. These accounts of resilience revealed the complex psychosocial processes and resources available to some adolescents
Moving epidemic method (MEM) applied to virology data as a novel real time tool to predict peak in seasonal influenza healthcare utilisation. The Scottish experience of the 2017/18 season to date
Scotland observed an unusual influenza A(H3N2)-
dominated 2017/18 influenza season with healthcare
services under significant pressure. We report the
application of the moving epidemic method (MEM) to
virology data as a tool to predict the influenza peak
activity period and peak week of swab positivity in the
current season. This novel MEM application has been
successful locally and is believed to be of potential use
to other countries for healthcare planning and building
wider community resilience
On the Deployment of DHCP
Constant-time symmetries and e-business have garnered great interest from both researchers and developers in the last several years. In this paper, authors confirm the analysis of interrupts. We describe a heuristic for stable models, which we call ViagePadge
Broad P V Absorption in the BALQSO, PG 1254+047: Column Densities, Ionizations and Metal Abundances in BAL Winds
This paper discusses the detection of P V 1118,1128 and other broad
absorption lines (BALs) in archival HST spectra of the low-redshift BALQSO, PG
1254+047. The P V identification is secured by excellent redshift and profile
coincidences with the other BALs, such as C IV 1548,1550 and Si IV 1393,1403,
and by photoionization calculations showing that other lines near this
wavelength, e.g. Fe III 1123, should be much weaker than P V. The observed BAL
strengths imply that either 1) there are extreme abundance ratios such as [C/H]
>~ +1.0, [Si/H] >~ +1.8 and [P/C] >~ +2.2, or 2) at least some of the lines are
much more optically thick than they appear. I argue that the significant
presence of P V absorption indicates severe line saturation, which is disguised
in the observed (moderate-strength) BALs because the absorber does not fully
cover the continuum source(s) along our line(s) of sight. Computed optical
depths for all UV resonance lines show that the observed BALs are consistent
with solar abundances if 1) the ionization parameter is at least moderately
high, log U >~ -0.6, 2) the total hydrogen column density is log N_H(cm-2) >~
22.0, and 3) the optical depths in strong lines like C IV and O VI 1032,1038
are >~25 and >~80, respectively. These optical depths and column densities are
at least an order of magnitude larger than expected from the residual
intensities in the BAL troughs, but they are consistent with the large
absorbing columns derived from X-ray observations of BALQSOs. The outflowing
BALR, at velocities from -15,000 to -27,000 km/s in PG 1254+047, is therefore a
strong candidate for the X-ray absorber in BALQSOs.Comment: 16 pages (LaTeX) plus 8 pages of figures in one file
(pg1254_figs.ps.gz), in press with Ap
The Devil is in the Details: Compact Structures in Pulsar Wind Nebulae
The large-scale structure of pulsar wind nebulae (PWNe) tells us a
considerable amount about their average magnetic fields, the total particle
input from the pulsar winds, and the confining pressure at their outer
boundaries. However, the details of the pulsar outflow, the sites of shocks and
particle acceleration, the effects of instabilities in the magnetic field, and
the interaction between the relativistic wind and the surrounding ejecta are
contained in small-scale structures, where we observe jets and toroidal
structures, time-varying emission from compact clumps, and filaments in both
the inner and outer regions of the nebulae. Here I review recent observational
studies of compact structures in PWNe and present current scenarios (and
questions) regarding their origin.Comment: 13 pages, 4 embedded EPS figures. Advances in Space Research, in
pres
Complex X-ray Absorption and the Fe Kalpha Profile in NGC 3516
We present data from simultaneous Chandra, XMM-Newton and BeppoSAX
observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and Nov.
We have investigated the nature of the very flat observed X-ray spectrum.
Chandra grating data show the presence of X-ray absorption lines, revealing two
distinct components of the absorbing gas, one which is consistent with our
previous model of the UV/X-ray absorber while the other, which is outflowing at
a velocity of ~1100 km/s has a larger column density and is much more highly
ionized. The broad-band spectral characteristics of the X-ray continuum
observed with XMM during 2001 April, reveal the presence of a third layer of
absorption consisting of a very large column (~2.5 x 10E23 cm^-2) of highly
ionized gas with a covering fraction ~50%. This low covering fraction suggests
that the absorber lies within a few lt-days of the X-ray source and/or is
filamentary in structure. Interestingly, these absorbers are not in thermal
equilibrium with one another. The two new components are too highly ionized to
be radiatively accelerated, which we suggest is evidence for a hydromagnetic
origin for the outflow. Applying our model to the Nov dataset, we can account
for the spectral variability primarily by a drop in the ionization states of
the absorbers, as expected by the change in the continuum flux. When this
complex absorption is accounted for we find the underlying continuum to be
typical of Seyfert 1 galaxies. The spectral curvature attributed to the high
column absorber, in turn, reduces estimates of the flux and extent of any broad
Fe emission line from the accretion disk.Comment: 33 pages, 9 figures, accepted for publication in Ap
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