2,826 research outputs found
A new method for the spectroscopic identification of stellar non-radial pulsation modes. II. Mode identification of the Delta Scuti star FG Virginis
We present a mode identification based on new high-resolution time-series
spectra of the non-radially pulsating Delta Scuti star FG~Vir (HD 106384, V =
6.57, A5V). From 2002 February to June a global Delta Scuti Network (DSN)
campaign, utilizing high-resolution spectroscopy and simultaneous photometry
has been conducted for FG~Vir in order to provide a theoretical pulsation
model. In this campaign we have acquired 969 Echelle spectra covering 147 hours
at six observatories. The mode identification was carried out by analyzing line
profile variations by means of the Fourier parameter fit method, where the
observational Fourier parameters across the line are fitted with theoretical
values. This method is especially well suited for determining the azimuthal
order m of non-radial pulsation modes and thus complementary with the method of
Daszynska-Daszkiewicz (2002) which does best at identifying the degree l. 15
frequencies between 9.2 and 33.5 c/d were detected spectroscopically. We
determined the azimuthal order m of 12 modes and constrained their harmonic
degree l. Only modes of low degree (l <= 4) were detected, most of them having
axisymmetric character mainly due to the relatively low projected rotational
velocity of FG Vir. The detected non-axisymmetric modes have azimuthal orders
between -2 and 1. We derived an inclination of 19 degrees, which implies an
equatorial rotational rate of 66 km/s.Comment: 14 pages, 26 figure
Scaling Behaviour and Complexity of the Portevin-Le Chatelier Effect
The plastic deformation of dilute alloys is often accompanied by plastic
instabilities due to dynamic strain aging and dislocation interaction. The
repeated breakaway of dislocations from and their recapture by solute atoms
leads to stress serrations and localized strain in the strain controlled
tensile tests, known as the Portevin-Le Chatelier (PLC) effect. In this present
work, we analyse the stress time series data of the observed PLC effect in the
constant strain rate tensile tests on Al-2.5%Mg alloy for a wide range of
strain rates at room temperature. The scaling behaviour of the PLC effect was
studied using two complementary scaling analysis methods: the finite variance
scaling method and the diffusion entropy analysis. From these analyses we could
establish that in the entire span of strain rates, PLC effect showed Levy walk
property. Moreover, the multiscale entropy analysis is carried out on the
stress time series data observed during the PLC effect to quantify the
complexity of the distinct spatiotemporal dynamical regimes. It is shown that
for the static type C band, the entropy is very low for all the scales compared
to the hopping type B and the propagating type A bands. The results are
interpreted considering the time and length scales relevant to the effect.Comment: 35 pages, 6 figure
Revealing the reality of undergraduate GP teaching in UK medical curricula: a cross-sectional questionnaire study
BACKGROUND: Time in general practice offers medical students opportunities to learn a breadth of clinical knowledge and skills relevant to their future clinical practice. Undergraduate experiences shape career decisions and current recommendations are that 25% of undergraduate curriculum time should be focused on general practice. However, previous work demonstrated that GP teaching had plateaued or reduced in UK medical schools. Therefore, an up-to-date description of undergraduate GP teaching is timely. AIM: To describe the current picture of UK undergraduate GP teaching, including the amount of time and resources allocated to GP teaching. DESIGN AND SETTING: A cross-sectional questionnaire study across 36 UK medical schools. METHOD: The questionnaire was designed based on a previous survey performed in 2011–2013, with additional questions on human and financial support allocated to GP teaching. The questionnaire was piloted and revised prior to distribution to leads of undergraduate GP teaching in UK medical schools. RESULTS: The questionnaire response rate was 100%. GP teaching constituted an average of 9.2% of medical curricula; this was lower than previous figures, though the actual number of GP sessions has remained static. The majority (n = 23) describe plans to increase GP teaching in their local curricula over the next 5 years. UK-wide average payment was 55.60 GBP/student/session of in-practice teaching, falling well below estimated costs to practices. Allocation of human resources was varied. CONCLUSION: Undergraduate GP teaching provision has plateaued since 2000 and falls short of national recommendations. Chronic underinvestment in GP teaching persists at a time when teaching is expected to increase. Both aspects need to be addressed to facilitate high-quality undergraduate GP teaching and promotion of the expert medical generalist role
FGFR2 amplification in colorectal adenocarcinoma
FGFR2 is recurrently amplified in 5% of gastric cancers and 1%–4% of breast cancers; however, this molecular alteration has never been reported in a primary colorectal cancer specimen. Preclinical studies indicate that several FGFR tyrosine-kinase inhibitors (TKIs), such as AZD4547, have in vitro activity against the FGFR2-amplified colorectal cell line, NCI-H716. The efficacy of these inhibitors is currently under investigation in clinical trials for breast and gastric cancer. Thus, better characterizing colorectal tumors for FGFR2 amplification could identify a subset of patients who may benefit from FGFR TKI therapies. Here, we describe a novel FGFR2 amplification identified by clinical next-generation sequencing in a primary colorectal cancer. Further characterization of the tumor by immunohistochemistry showed neuroendocrine differentiation, similar to the reported properties of the NCI-H716 cell line. These findings demonstrate that the spectrum of potentially clinically actionable mutations detected by targeted clinical sequencing panels is not limited to only single-nucleotide polymorphisms and insertions/deletions but also to copy-number alterations.</jats:p
Quasi-Static Brittle Fracture in Inhomogeneous Media and Iterated Conformal Maps: Modes I, II and III
The method of iterated conformal maps is developed for quasi-static fracture
of brittle materials, for all modes of fracture. Previous theory, that was
relevant for mode III only, is extended here to mode I and II. The latter
require solution of the bi-Laplace rather than the Laplace equation. For all
cases we can consider quenched randomness in the brittle material itself, as
well as randomness in the succession of fracture events. While mode III calls
for the advance (in time) of one analytic function, mode I and II call for the
advance of two analytic functions. This fundamental difference creates
different stress distribution around the cracks. As a result the geometric
characteristics of the cracks differ, putting mode III in a different class
compared to modes I and II.Comment: submitted to PRE For a version with qualitatively better figures see:
http://www.weizmann.ac.il/chemphys/ander
Critical Dynamics of Burst Instabilities in the Portevin-Le Chatelier Effect
We investigate the Portevin-Le Chatelier effect (PLC), by compressing Al-Mg
alloys in a very large deformation range, and interpret the results from the
viewpoint of phase transitions and critical phenomena. The system undergoes two
dynamical phase transitions between intermittent (or "jerky") and "laminar"
plastic dynamic phases. Near these two dynamic critical points, the order
parameter 1/\tau of the PLC effect exhibits large fluctuations, and "critical
slowing down" (i.e., the number of bursts, or plastic instabilities, per
unit time slows down considerably).Comment: the published 4-page version is in the PRL web sit
Use of ERTS-1 data to access and monitor change in the west side of the San Joaquin Valley and central coastal zone of California
There are no author-identified significant results in this report
Particle displacements in the elastic deformation of amorphous materials: local fluctuations vs. non-affine field
We study the local disorder in the deformation of amorphous materials by
decomposing the particle displacements into a continuous, inhomogeneous field
and the corresponding fluctuations. We compare these fields to the commonly
used non-affine displacements in an elastically deformed 2D Lennard-Jones
glass. Unlike the non-affine field, the fluctuations are very localized, and
exhibit a much smaller (and system size independent) correlation length, on the
order of a particle diameter, supporting the applicability of the notion of
local "defects" to such materials. We propose a scalar "noise" field to
characterize the fluctuations, as an additional field for extended continuum
models, e.g., to describe the localized irreversible events observed during
plastic deformation.Comment: Minor corrections to match the published versio
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