180 research outputs found
Hybrid Curvatons from Broken Symmetry
We present a new general mechanism for generating curvature perturbations
after inflation. Our model is based on the simple assumption that a field that
starts to oscillate after inflation has a potential characterized by an
underlying global symmetry that is slightly or badly broken. Inhomogeneous
preheating occurs due to the oscillation with the broken symmetry. Unlike the
traditional curvaton model, we will not identify the curvaton with the
oscillating field. The curvaton is identified with the preheat field that could
be either a scalar, vector, or fermionic field. We introduce an explicit mass
term for the curvaton, which is important for later evolution and the decay.
Our present model represents the simplest example of the hybrid of the
curvatons and inhomogeneous preheating.Comment: 21pages, 5 figures, accepted for publication in JHE
Latin American Anatomists’ views on human body dissection and donation
Background
Studies abound regarding the medical students' views on the importance of anatomy and the dissection of human bodies, but little is known about the views of Latin American Anatomists.
Methods
A survey was carried out to test several hypotheses among anatomists of the Americas about how they perceive their professional identity, the use and role of dissection in their undergraduate courses, and the approval degree of bequeathing their body for anatomical teaching/research; another goal was ascertaining to what extent their attitude on these topics depended on gender, length of teaching experience and belief in the afterlife.
Results
One hundred and forty-five anatomists from thirteen Latin American and Caribbean Countries took the survey; 79% stated the main role of an anatomist is teaching; 34% recorded their undergraduate students dissected human cadavers as part of their anatomy lab course—undergraduates dissecting less in the less experienced anatomists’ courses (p = 0.0002). Most anatomists said dissection was a training tool for undergraduate students, a tool for developing professional skills, and a tool to help control emotions—most experienced anatomists stood out from the rest saying dissection is only to teach anatomy (p < 0.001), even if such response was the least valued by them among all replies. Men differed from women in valuing dissection as a tool to help control emotions (p = 0.006); less experienced anatomists held the opposite (p < 0.0001). Approval of a close doctor-patient relationship diverged, being different between the most and the least experienced anatomists (p = 0.01). Anatomists said they would donate only their organs (44%), whole body (9%) and both organs and body (46%). Undecided anatomists about the belief in life after death were the least in favor of donation (p = 0.05)
Physics of Solar Prominences: II - Magnetic Structure and Dynamics
Observations and models of solar prominences are reviewed. We focus on
non-eruptive prominences, and describe recent progress in four areas of
prominence research: (1) magnetic structure deduced from observations and
models, (2) the dynamics of prominence plasmas (formation and flows), (3)
Magneto-hydrodynamic (MHD) waves in prominences and (4) the formation and
large-scale patterns of the filament channels in which prominences are located.
Finally, several outstanding issues in prominence research are discussed, along
with observations and models required to resolve them.Comment: 75 pages, 31 pictures, review pape
Positive correlation between fluoride release and acid erosion of restorative glass-ionomer cements.
OBJECTIVE: The aim of this study was to determine whether there is a correlation between acid erosion and fluoride release of conventional glass ionomer cements. METHODS: Ten specimens for each material were prepared for fluoride release tests and five for acid erosion tests separately. After placed in pH cycling solution, concentration of fluoride was measured by a fluoride-ion selective electrode each day for 15 days. For the acid erosion test, specimens were immersed in a lactic acid solution and their depth measured with a spring-loaded dial gauge. The data were submitted to 3-way ANOVA, followed by Tukey's test (p0.05). The highest acid erosion values were registered for Magic Glass, Ion Z, VitroFil and Maxxion R, which exceeded the maximum stipulated by the relevant ISO test (ISO 9917-1). A positive linear correlation (r2=0.4886) was found for both properties, i.e., higher fluoride release is related to higher acid erosion. SIGNIFICANCE: Acid erosion and fluoride release are related properties of GICs, though factors such as pH and P/L ratio lead to differences between actual values for individual brands of these materials
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Tension between SN and BAO: current status and future forecasts
Using real and synthetic Type Ia SNe (SNeIa) and baryon acoustic oscillations
(BAO) data representing current observations forecasts, this paper investigates
the tension between those probes in the dark energy equation of state (EoS)
reconstruction considering the well known CPL model and Wang's low correlation
reformulation. In particular, here we present simulations of BAO data from both
the the radial and transverse directions. We also explore the influence of
priors on Omega_m and Omega_b on the tension issue, by considering 1-sigma
deviations in either one or both of them. Our results indicate that for some
priors there is no tension between a single dataset (either SNeIa or BAO) and
their combination (SNeIa+BAO). Our criterion to discern the existence of
tension (sigma-distance) is also useful to establish which is the dataset with
most constraining power; in this respect SNeIa and BAO data switch roles when
current and future data are considered, as forecasts predict and spectacular
quality improvement on BAO data. We also find that the results on the tension
are blind to the way the CPL model is addressed: there is a perfect match
between the original formulation and that by the low correlation optimized, but
the errors on the parameters are much narrower in all cases of our exhaustive
exploration, thus serving the purpose of stressing the convenience of this
reparametrization.Comment: 21 pages, under review in JCA
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