795 research outputs found
Esophageal Carcinoma Histology Affects Perioperative Morbidity Following Open Esophagogastrectomy
Background. Esophagectomy for esophageal cancer is being practiced routinely with favorable results at many centers. We sought to determine if tumor histology is a powerful surrogate marker for perioperative morbidity. Methods. Seventy three consecutive patients managed operatively were reviewed from our prospectively maintained database.
Results. Adenocarcinoma (AC) was present in 52 (71%) and squamous cell (SCC) in 21 (29%). The use of neoadjuvant therapy was similar for the AC (34.62%) and SCC (42.86%) groups. The SCC group had a higher incidence of prior pulmonary disease than the AC group (23.8% versus 5.8%, resp.; P = .03). SCC patients were more likely to have a prolonged ICU stay than AC patients (P = .004) despite similar complication rates, EBL, and prognostic nutritional index. The SCC group did, however, experience higher grades of complications (P = .0053). Conclusions. Presence of SCC was the single best predictor of prolonged ICU stay and more severe complications as defined by this study. Only a past history of pulmonary disease was different between the two histologic subgroups
Simulations of in situ X-ray diffraction from uniaxially compressed highly textured polycrystalline targets
A growing number of shock compression experiments, especially those involving laser compression, are taking advantage of in situ x-ray diffraction as a tool to interrogate structure and microstructure evolution. Although these experiments are becoming increasingly sophisticated, there has been little work on exploiting the textured nature of polycrystalline targets to gain information on sample response. Here, we describe how to generate simulated x-ray diffraction patterns from materials with an arbitrary texture function subject to a general deformation gradient. We will present simulations of Debye-Scherrer x-ray diffraction from highly textured polycrystalline targets that have been subjected to uniaxial compression, as may occur under planar shock conditions. In particular, we study samples with a fibre texture, and find that the azimuthal dependence of the diffraction patterns contains information that, in principle, affords discrimination between a number of similar shock-deformation mechanisms. For certain cases we compare our method with results obtained by taking the Fourier Transform of the atomic positions calculated by classical molecular dynamics simulations. Illustrative results are presented for the shock-induced - phase transition in iron, the - transition in titanium and deformation due to twinning in tantalum that is initially preferentially textured along [001] and [011]. The simulations are relevant to experiments that can now be performed using 4th generation light sources, where single-shot x-ray diffraction patterns from crystals compressed via laser-ablation can be obtained on timescales shorter than a phonon period
Local helioseismology of sunspot regions: comparison of ring-diagram and time-distance results
Local helioseismology provides unique information about the subsurface
structure and dynamics of sunspots and active regions. However, because of
complexity of sunspot regions local helioseismology diagnostics require careful
analysis of systematic uncertainties and physical interpretation of the
inversion results. We present new results of comparison of the ring-diagram
analysis and time-distance helioseismology for active region NOAA 9787, for
which a previous comparison showed significant differences in the subsurface
sound-speed structure, and discuss systematic uncertainties of the measurements
and inversions. Our results show that both the ring-diagram and time-distance
techniques give qualitatively similar results, revealing a characteristic
two-layer seismic sound-speed structure consistent with the results for other
active regions. However, a quantitative comparison of the inversion results is
not straightforward. It must take into account differences in the sensitivity,
spatial resolution and the averaging kernels. In particular, because of the
acoustic power suppression, the contribution of the sunspot seismic structure
to the ring-diagram signal can be substantially reduced. We show that taking
into account this effect reduces the difference in the depth of transition
between the negative and positive sound-speed variations inferred by these
methods. Further detailed analysis of the sensitivity, resolution and averaging
properties of the local helioseismology methods is necessary for consolidation
of the inversion results. It seems to be important that both methods indicate
that the seismic structure of sunspots is rather deep and extends to at least
20 Mm below the surface, putting constraints on theoretical models of sunspots.Comment: 10 pages, 10 figures, submitted to Journal of Physics: Conference
Series (JPCS) GONG 2010 - SoHO 24 "A new era of seismology of the Sun and
solar-like stars", June 27 - July 2, 2010 Aix-en-Provence, Franc
Defining the cognitive phenotype of autism
Although much progress has been made in determining the cognitive profile of strengths and weaknesses that characterise individuals with autism spectrum disorders (ASDs), there remain a number of outstanding questions. These include how universal strengths and deficits are; whether cognitive subgroups exist; and how cognition is associated with core autistic behaviours, as well as associated psychopathology. Several methodological factors have contributed to these limitations in our knowledge, including: small sample sizes, a focus on single domains of cognition, and an absence of comprehensive behavioural phenotypic information. To attempt to overcome some of these limitations, we assessed a wide range of cognitive domains in a large sample (N = 100) of 14- to 16-year-old adolescents with ASDs who had been rigorously behaviourally characterised. In this review, we will use examples of some initial findings in the domains of perceptual processing, emotion processing and memory, both to outline different approaches we have taken to data analysis and to highlight the considerable challenges to better defining the cognitive phenotype(s) of ASDs. Enhanced knowledge of the cognitive phenotype may contribute to our understanding of the complex links between genes, brain and behaviour, as well as inform approaches to remediation
Deliberating performance targets workshop: Potential paths for emerging PM2.5 and O3 air sensor progress
The United States Environmental Protection Agency held an international two-day workshop in June 2018 to deliberate possible performance targets for non-regulatory fine particulate matter (PM2.5) and ozone (O3) air sensors. The need for a workshop arose from the lack of any market-wide manufacturer requirement for documented sensor performance evaluations, the lack of any independent third party or government-based sensor performance certification program, and uncertainty among all users as to the general usability of air sensor data. A multi-sector subject matter expert panel was assembled to facilitate an open discussion on these issues with multiple stakeholders. This summary provides an overview of the workshop purpose, key findings from the deliberations, and considerations for future actions specific to sensors. Important findings concerning PM2.5 and O3 sensors included the lack of consistent performance indicators and statistical metrics as well as highly variable data quality requirements depending on the intended use. While the workshop did not attempt to yield consensus on any topic, a key message was that a number of possible future actions would be beneficial to all stakeholders regarding sensor technologies. These included documentation of best practices, sharing quality assurance results along with sensor data, and the development of a common performance target lexicon, performance targets, and test protocols. Keywords: Low-cost air quality sensors, Performance targets, PM2.5, Ozon
Modeling the Subsurface Structure of Sunspots
While sunspots are easily observed at the solar surface, determining their
subsurface structure is not trivial. There are two main hypotheses for the
subsurface structure of sunspots: the monolithic model and the cluster model.
Local helioseismology is the only means by which we can investigate
subphotospheric structure. However, as current linear inversion techniques do
not yet allow helioseismology to probe the internal structure with sufficient
confidence to distinguish between the monolith and cluster models, the
development of physically realistic sunspot models are a priority for
helioseismologists. This is because they are not only important indicators of
the variety of physical effects that may influence helioseismic inferences in
active regions, but they also enable detailed assessments of the validity of
helioseismic interpretations through numerical forward modeling. In this paper,
we provide a critical review of the existing sunspot models and an overview of
numerical methods employed to model wave propagation through model sunspots. We
then carry out an helioseismic analysis of the sunspot in Active Region 9787
and address the serious inconsistencies uncovered by
\citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find
that this sunspot is most probably associated with a shallow, positive
wave-speed perturbation (unlike the traditional two-layer model) and that
travel-time measurements are consistent with a horizontal outflow in the
surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic
Asteroseismology of Procyon with SOPHIE
This paper reports a 9-night asteroseismic observation program conducted in
January 2007 with the new spectrometer Sophie at the OHP 193-cm telescope, on
the F5 IV-V target Procyon A. This first asteroseismic program with Sophie was
intended to test the performance of the instrument with a bright but demanding
asteroseismic target and was part of a multisite network. The Sophie spectra
have been reduced with the data reduction software provided by OHP. The Procyon
asteroseismic data were then analyzed with statistical tools. The asymptotic
analysis has been conducted considering possible curvature in the echelle
diagram analysis. These observations have proven the efficient performance of
Sophie used as an asteroseismometer, and succeed in a clear detection of the
large spacing. An \'echelle diagram based on the 54-Hz spacing shows clear
ridges. Identification of the peaks exhibits large spacings varying from about
52 Hz to 56 Hz.Comment: 7 pages, 7 figure
Advances in Global and Local Helioseismology: an Introductory Review
Helioseismology studies the structure and dynamics of the Sun's interior by
observing oscillations on the surface. These studies provide information about
the physical processes that control the evolution and magnetic activity of the
Sun. In recent years, helioseismology has made substantial progress towards the
understanding of the physics of solar oscillations and the physical processes
inside the Sun, thanks to observational, theoretical and modeling efforts. In
addition to the global seismology of the Sun based on measurements of global
oscillation modes, a new field of local helioseismology, which studies
oscillation travel times and local frequency shifts, has been developed. It is
capable of providing 3D images of the subsurface structures and flows. The
basic principles, recent advances and perspectives of global and local
helioseismology are reviewed in this article.Comment: 86 pages, 46 figures; "Pulsation of the Sun and Stars", Lecture Notes
in Physics, Vol. 832, Rozelot, Jean-Pierre; Neiner, Coralie (Eds.), 201
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