1,557 research outputs found
Unsolicited written narratives as a methodological genre in terminal illness: challenges and limitations
Stories about illness have proven invaluable in helping health professionals understand illness experiences. Such narratives have traditionally been solicited by researchers through interviews and the collection of personal writings, including diaries. These approaches are, however, researcher driven; the impetus for the creation of the story comes from the researcher and not the narrator. In recent years there has been exponential growth in illness narratives created by individuals, of their own volition, and made available for others to read in print or as Internet accounts. We sought to determine whether it was possible to identify such material for use as research data to explore the subject of living with the terminal illness amyotrophic lateral sclerosis/motor neuron disease—the contention being that these accounts are narrator driven and therefore focus on issues of greatest importance to the affected person. We encountered and sought to overcome a number of methodological and ethical challenges, which is our focus here
Si-compatible candidates for high-K dielectrics with the Pbnm perovskite structure
We analyze both experimentally (where possible) and theoretically from
first-principles the dielectric tensor components and crystal structure of five
classes of Pbnm perovskites. All of these materials are believed to be stable
on silicon and are therefore promising candidates for high-K dielectrics. We
also analyze the structure of these materials with various simple models,
decompose the lattice contribution to the dielectric tensor into force constant
matrix eigenmode contributions, explore a peculiar correlation between
structural and dielectric anisotropies in these compounds and give phonon
frequencies and infrared activities of those modes that are infrared-active. We
find that CaZrO_3, SrZrO_3, LaHoO_3, and LaYO_3 are among the most promising
candidates for high-K dielectrics among the compounds we considered.Comment: 17 pages, 9 figures, 4 tables. Supplementary information:
http://link.aps.org/supplemental/10.1103/PhysRevB.82.064101 or
http://www.physics.rutgers.edu/~sinisa/highk/supp.pd
Vector vortex coronagraph: first results in the visible
We report the status of JPL and JDSU ongoing technological developments and contrast results of the vector vortex coronagraph (VVC) made out of liquid crystal polymers (LCP). The first topological charge 4 VVC was tested on the high contrast imaging testbed (HCIT) around 800 nm, under vacuum and with active wavefront control (32x32 Xinetics deformable mirror). We measured the inner working angle or IWA (50% off-axis transmission) at ~ 1.8λ/d. A one-sided dark hole ranging from 3λ/d to 10λ/d was created in polarized light, showing a mean contrast of ~ 2 × 10^(-7) over a 10% bandwidth. This contrast was maintained very close in (3 λ/d) in a reduced 2% bandwidth. These tests begin to demonstrate the potential of the LCP technology in the most demanding application of a space-based telescope dedicated to extrasolar planet characterization. The main limitations were identified as coming from incoherent sources such as multiple reflections, and residual chromaticity. A second generation of improved masks tackling these issues is being manufactured and will be tested on the HCIT in the coming months
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Sport-Related Concussions: Symptom Recurrence After Return to Exercise
Background: Current guidelines dictate a gradual exercise progression after a concussion; however, it is unclear what proportion of athletes experience a recurrence of symptoms once they are symptom free at rest. Estimating the proportion of athletes and predictors of symptom recurrence would help shape return-to-play protocols. Purpose: To determine the proportion and associated risk factors of athletes who have a recurrence of concussion symptoms with exercise after being symptom free at rest. Study Design: Case-control study; Level of evidence, 3. Methods: Between October 1, 2009 and July 31, 2011, we studied patients from a sport concussion clinic located within a tertiary care regional children’s hospital. Patients were queried at every visit using a standardized questionnaire. Our main outcome variable was recurrence of symptoms with exercise after being symptom free at rest at some point in their recovery. Cofactors included age, sex, loss of consciousness with injury, prior concussion (diagnosed and undiagnosed), Post-Concussion Symptom Scale (PCSS) score, time until clinical presentation, and duration of symptoms. Results: Of the 217 patients included, 25 (12%) experienced a return of symptoms. Losing consciousness at the time of injury and a longer duration between injury and clinical presentation were associated with a decreased risk of symptoms recurring with exercise. Conversely, athletes who had sustained previously undiagnosed concussions and had suffered a longer duration of symptoms at rest were at an increased risk of symptom recurrence with exercise. Conclusion: Relatively few athletes who are symptom free at rest after a concussion will have a recurrence of symptoms when they resume exercise. The risk of symptoms recurring with exercise may be greater among those athletes who sustained previously undiagnosed concussions and had a longer period of symptoms at rest. The early identification of athletes who may be at risk of symptom recurrence will help mold treatment guidelines and exercise progression protocols
Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts
NASA's Dawn spacecraft observations of asteroid (4) Vesta reveal a surface
with the highest albedo and color variation of any asteroid we have observed so
far. Terrains rich in low albedo dark material (DM) have been identified using
Dawn Framing Camera (FC) 0.75 {\mu}m filter images in several geologic
settings: associated with impact craters (in the ejecta blanket material and/or
on the crater walls and rims); as flow-like deposits or rays commonly
associated with topographic highs; and as dark spots (likely secondary impacts)
nearby impact craters. This DM could be a relic of ancient volcanic activity or
exogenic in origin. We report that the majority of the spectra of DM are
similar to carbonaceous chondrite meteorites mixed with materials indigenous to
Vesta. Using high-resolution seven color images we compared DM color properties
(albedo, band depth) with laboratory measurements of possible analog materials.
Band depth and albedo of DM are identical to those of carbonaceous chondrite
xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison
CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band
depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance
in DM (1-6 vol%) is consistent with howardite meteorites. We find no evidence
for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of
DM. Our modeling efforts using impact crater scaling laws and numerical models
of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta
during the formation of the ~400 km Veneneia basin by a low-velocity (<2
km/sec) carbonaceous impactor. This discovery is important because it
strengthens the long-held idea that primitive bodies are the source of carbon
and probably volatiles in the early Solar System.Comment: Icarus (Accepted) Pages: 58 Figures: 15 Tables:
Making the Earth: Combining Dynamics and Chemistry in the Solar System
No terrestrial planet formation simulation completed to date has considered
the detailed chemical composition of the planets produced. While many have
considered possible water contents and late veneer compositions, none have
examined the bulk elemental abundances of the planets produced as an important
check of formation models. Here we report on the first study of this type. Bulk
elemental abundances based on disk equilibrium studies have been determined for
the simulated terrestrial planets of O'Brien et al. (2006). These abundances
are in excellent agreement with observed planetary values, indicating that the
models of O'Brien et al. (2006) are successfully producing planets comparable
to those of the Solar System in terms of both their dynamical and chemical
properties. Significant amounts of water are accreted in the present
simulations, implying that the terrestrial planets form "wet" and do not need
significant water delivery from other sources. Under the assumption of
equilibrium controlled chemistry, the biogenic species N and C still need to be
delivered to the Earth as they are not accreted in significant proportions
during the formation process. Negligible solar photospheric pollution is
produced by the planetary formation process. Assuming similar levels of
pollution in other planetary systems, this in turn implies that the high
metallicity trend observed in extrasolar planetary systems is in fact
primordial.Comment: 61 pages (including online material), 12 figures (7 in paper, 5
online). Accepted to Icaru
Swift Observations of GRB 050603: An afterglow with a steep late time decay slope
We report the results of Swift observations of the Gamma Ray Burst GRB
050603. With a V magnitude V=18.2 about 10 hours after the burst the optical
afterglow was the brightest so far detected by Swift and one of the brightest
optical afterglows ever seen. The Burst Alert Telescope (BAT) light curves show
three fast-rise-exponential-decay spikes with =12s and a fluence of
7.6 ergs cm in the 15-150 keV band. With an ergs it was also one of the most energetic
bursts of all times. The Swift spacecraft began observing of the afterglow with
the narrow-field instruments about 10 hours after the detection of the burst.
The burst was bright enough to be detected by the Swift UV/Optical telescope
(UVOT) for almost 3 days and by the X-ray Telescope (XRT) for a week after the
burst. The X-ray light curve shows a rapidly fading afterglow with a decay
index =1.76. The X-ray energy spectral index was
=0.71\plm0.10 with the column density in agreement with the
Galactic value. The spectral analysis does not show an obvious change in the
X-ray spectral slope over time. The optical UVOT light curve decays with a
slope of =1.8\plm0.2.
The steepness and the similarity of the optical and X-ray decay rates suggest
that the afterglow was observed after the jet break. We estimate a jet opening
angle of about 1-2Comment: 14 pages, accepted for publication in Ap
Angular Diameters of the G Subdwarf Cassiopeiae A and the K Dwarfs Draconis and HR 511 from Interferometric Measurements with the CHARA Array
Using the longest baselines of the CHARA Array, we have measured the angular
diameter of the G5 V subdwarf Cas A, the first such determination for a
halo population star. We compare this result to new diameters for the higher
metallicity K0 V stars, Dra and HR 511, and find that the metal-poor
star, Cas A, has an effective temperature ( K),
radius (), and absolute luminosity
() comparable to the other two stars with later
spectral types. We show that stellar models show a discrepancy in the predicted
temperature and radius for Cas A, and we discuss these results and how
they provide a key to understanding the fundamental relationships for stars
with low metallicity.Comment: Accepted for publication in The Astrophysical Journa
Development and Implementation of a High Throughput Screen for the Human Sperm-Specific Isoform of Glyceraldehyde 3-Phosphate Dehydrogenase (GAPDHS)
Glycolytic isozymes that are restricted to the male germline are potential targets for the development of reversible, non-hormonal male contraceptives. GAPDHS, the sperm-specific isoform of glyceraldehyde-3-phosphate dehydrogenase, is an essential enzyme for glycolysis making it an attractive target for rational drug design. Toward this goal, we have optimized and validated a high-throughput spectrophotometric assay for GAPDHS in 384-well format. The assay was stable over time and tolerant to DMSO. Whole plate validation experiments yielded Z’ values >0.8 indicating a robust assay for HTS. Two compounds were identified and confirmed from a test screen of the Prestwick collection. This assay was used to screen a diverse chemical library and identified fourteen small molecules that modulated the activity of recombinant purified GAPDHS with confirmed IC50 values ranging from 1.8 to 42 µM. These compounds may provide useful scaffolds as molecular tools to probe the role of GAPDHS in sperm motility and long term to develop potent and selective GAPDHS inhibitors leading to novel contraceptive agents
The p53 codon 72 PRO/PRO genotype may be associated with initial central visual field defects in Caucasians with primary open angle glaucoma
Background: Loss of vision in glaucoma is due to apoptotic retinal ganglion cell loss. While p53 modulates apoptosis, gene
association studies between p53 variants and glaucoma have been inconsistent. In this study we evaluate the association
between a p53 variant functionally known to influence apoptosis (codon 72 Pro/Arg) and the subset of primary open angle
glaucoma (POAG) patients with early loss of central visual field.
Methods: Genotypes for the p53 codon 72 polymorphism (Pro/Arg) were obtained for 264 POAG patients and 400 controls
from the U.S. and in replication studies for 308 POAG patients and 178 controls from Australia (GIST). The glaucoma patients
were divided into two groups according to location of initial visual field defect (either paracentral or peripheral). All cases
and controls were Caucasian with European ancestry.
Results: The p53-PRO/PRO genotype was more frequent in the U.S. POAG patients with early visual field defects in the
paracentral regions compared with those in the peripheral regions or control group (p = 2.761025). We replicated this
finding in the GIST cohort (p = 7.361023, and in the pooled sample (p = 6.661027) and in a meta-analysis of both the US
and GIST datasets (1.361026, OR 2.17 (1.58–2.98 for the PRO allele).
Conclusions: These results suggest that the p53 codon 72 PRO/PRO genotype is potentially associated with early
paracentral visual field defects in primary open-angle glaucoma patients.NHMRC: This study was supported by National Institutes of Health/National Eye Institute grants: R01EY015872 (Wiggs), R01EY015473 (Pasquale), P30EY014104
(Wiggs), Research to Prevent Blindness (Wiggs, Pasquale, Realini), the Harvard Glaucoma Center of Excellence (Wiggs, Pasquale), The Massachusetts Lions Eye
Research Fund (Wiggs, Pasquale), National Health & Medical Research Council Project grant 229960, the Ophthalmic Research Institute of Australia, and Glaucoma
Australia. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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