2,842 research outputs found
Self-bound dense objects in holographic QCD
We study a self-bound dense object in the hard wall model. We consider a
spherically symmetric dense object which is characterized by its radial density
distribution and non-uniform but spherically symmetric chiral condensate. For
this we analytically solve the partial differential equations in the hard wall
model and read off the radial coordinate dependence of the density and chiral
condensate according to the AdS/CFT correspondence. We then attempt to describe
nucleon density profiles of a few nuclei within our framework and observe that
the confinement scale changes from a free nucleon to a nucleus. We briefly
discuss how to include the effect of higher dimensional operator into our
study. We finally comment on possible extensions of our work.Comment: 17 pages, 5 figures, figures replaced, minor revision, to appear in
JHE
Candida esophageal perforation and esophagopleural fistula: a case report
<p>Abstract</p> <p>Introduction</p> <p>Esophageal perforation is a rare disease, which can lead to significant morbidity and mortality. Its clinical presentation can mimic other disease processes and, therefore, it can be easily misdiagnosed. <it>Candida </it>infection of the esophagus is an extremely rare cause of esophageal perforation.</p> <p>Case presentation</p> <p>We report the youngest pediatric case in the medical literature of spontaneous esophageal perforation and an esophagopleural fistula due to <it>Candida </it>infection.</p> <p>Conclusion</p> <p>A high index of suspicion, especially in the presence of <it>Candida </it>empyema and the absence of disseminated infection, should raise the possibility of esophageal perforation with esophagopleural fistula formation. This can lead to early diagnosis and surgical intervention, which would decrease the high mortality rate of this rare condition.</p
Genetic testing of children for adult-onset conditions: opinions of the British adult population and implications for clinical practice
This study set out to explore the attitudes of a representative sample of the British public towards genetic testing in children to predict disease in the future. We sought opinions about genetic testing for adult-onset conditions for which no prevention/treatment is available during childhood, and about genetic 'carrier' status to assess future reproductive risks. The study also examined participants' level of agreement with the reasons professional organisations give in favour of deferring such testing. Participants (n=2998) completed a specially designed questionnaire, distributed by email. Nearly half of the sample (47%) agreed that parents should be able to test their child for adult-onset conditions, even if there is no treatment or prevention at time of testing. This runs contrary to professional guidance about genetic testing in children. Testing for carrier status was supported by a larger proportion (60%). A child's future ability to decide for her/himself if and when to be tested was the least supported argument in favour of deferring testing.European Journal of Human Genetics advance online publication, 5 November 2014; doi:10.1038/ejhg.2014.221
Neutron Scattering and Its Application to Strongly Correlated Systems
Neutron scattering is a powerful probe of strongly correlated systems. It can
directly detect common phenomena such as magnetic order, and can be used to
determine the coupling between magnetic moments through measurements of the
spin-wave dispersions. In the absence of magnetic order, one can detect diffuse
scattering and dynamic correlations. Neutrons are also sensitive to the
arrangement of atoms in a solid (crystal structure) and lattice dynamics
(phonons). In this chapter, we provide an introduction to neutrons and neutron
sources. The neutron scattering cross section is described and formulas are
given for nuclear diffraction, phonon scattering, magnetic diffraction, and
magnon scattering. As an experimental example, we describe measurements of
antiferromagnetic order, spin dynamics, and their evolution in the
La(2-x)Ba(x)CuO(4) family of high-temperature superconductors.Comment: 31 pages, chapter for "Strongly Correlated Systems: Experimental
Techniques", edited by A. Avella and F. Mancin
Pervasiveness of the IQ Rise: A Cross-Temporal Meta-Analysis
Background: Generational IQ gains in the general population (termed the Flynn effect) show an erratic pattern across different nations as well as across different domains of intelligence (fluid vs crystallized). Gains of fluid intelligence in different countries have been subject to extensive research, but less attention was directed towards gains of crystallized intelligence, probably due to evidence from the Anglo-American sphere suggesting only slight gains on this measure. In the present study, development of crystallized intelligence in the German speaking general population is assessed. Methodology/Principal Findings: To investigate whether IQ gains for crystallized intelligence are in progress in Germanspeaking countries, two independent meta-analyses were performed. By means of a cited reference search in ISI Web of Science, all studies citing test manuals and review articles of two widely-used salient measures of crystallized intelligence were obtained. Additionally, the electronic database for German academic theses was searched to identify unpublished studies employing these tests. All studies reporting participants mean IQ or raw scores of at least one of the two measures were included in the present analyses, yielding over 500 studies (.1,000 samples;.45,000 individuals). We found a significant positive association between years of test performance and intelligence (1971–2007) amounting to about 3.5 IQ points per decade. Conclusions/Significance: This study clearly demonstrates that crystallized IQ gains are substantial and of comparabl
Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
In high-transition temperature (high-Tc) copper oxides, it is generally
believed that antiferromagnetism plays a fundamental role in the
superconducting mechanism because superconductivity occurs when mobile
electrons or holes are doped into the antiferromagnetic parent compounds. The
recent discovery of superconductivity in the rare-earth (R) iron-based oxide
systems [RO1-xFxFeAs] has generated enormous interest because these materials
are the first noncopper oxide superconductors with Tc exceeding 50 K. The
parent (nonsuperconducting) LaOFeAs material is metallic but shows anomalies
near 150 K in both resistivity and dc magnetic susceptibility. While optical
conductivity and theoretical calculations suggest that LaOFeAs exhibits a
spin-density-wave (SDW) instability that is suppressed with doping electrons to
form superconductivity, there has been no direct evidence of the SDW order.
Here we use neutron scattering to demonstrate that LaOFeAs undergoes an abrupt
structural distortion below ~150 K, changing the symmetry from tetragonal
(space group P4/nmm) to monoclinic (space group P112/n) at low temperatures,
and then followed with the development of long range SDW-type antiferromagnetic
order at ~134 K with a small moment but simple magnetic structure. Doping the
system with flourine suppresses both the magnetic order and structural
distortion in favor of superconductivity. Therefore, much like high-Tc copper
oxides, the superconducting regime in these Fe-based materials occurs in close
proximity to a long-range ordered antiferromagnetic ground state. Since the
discovery of longComment: 15 pages, 4 figures, and 3 table
Neonatal intensive care parent satisfaction: a multicenter study translating and validating the Italian EMPATHIC-N questionnaire
Background: In Neonatal Intensive Care Units (NICUs), parent satisfaction and their experiences are fundamental to assess clinical practice and improve the quality of care delivered to infants and parents. Recently, a specific instrument, the EMpowerment of PArents in THe Intensive Care-Neonatology (EMPATHIC-N), has been developed in the Netherlands. This instrument investigated different domains of care in NICUs from a family-centered care perspective. In Italy, no rigorous instruments are available to evaluate parent satisfaction and experiences in NICU with family-centered care. The aim of this study was to translate and validate the EMPATHIC-N instrument into Italian language measuring parent satisfaction. Methods: A psychometric study was conducted in nine Italian NICUs. The hospitals were allocated across Italy: four in the North, four in Central region, one in the South. Parents whose infants were discharged from the Units were enrolled. Parents whose infants died were excluded. Results: Back-forward translation was conducted. Twelve parents reviewed the instrument to assess the cultural adaptation; none of the items fell below the cut-off of 80% agreement. A total of 186 parents of infants who were discharged from nine NICUs were invited to participate and 162 parents responded and returned the questionnaire (87%). The mean scores of the individual items varied between 4.3 and 5.9. Confirmatory factor analysis was performed and all factor loadings were statistically significant with the exception of item ‘Our cultural background was taken into account’. The items related to overall satisfaction showed a higher trend with mean values of 5.8 and 5.9. The Cronbach’s alpha’s (at domain level 0.73-0.92) and corrected item-total scale correlations revealed high reliability estimates. Conclusions: The Italian EMPATHIC-N showed to be a valid and reliable instrument measuring parent satisfaction in NICUs from a family-centered care perspective. Indeed, it had good psychometric properties, validity, and reliability. Furthermore, this instrument is fundamental for further research and internationally benchmarking
Brain mass estimation by head circumference and body mass methods in neonatal glycaemic modelling and control
Introduction: Hyperglycaemia is a common complication of stress and prematurity in extremely low-birth-weight infants. Model-based insulin therapy protocols have the ability to safely improve glycaemic control for this group. Estimating non-insulin-mediated brain glucose uptake by the central nervous system in these models is typically done using population-based body weight models, which may not be ideal. Method: A head circumference-based model that separately treats small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) infants is compared to a body weight model in a retrospective analysis of 48 patients with a median birth weight of 750g and median gestational age of 25 weeks. Estimated brain mass, model-based insulin sensitivity (SI) profiles, and projected glycaemic control outcomes are investigated. SGA infants (5) are also analyzed as a separate cohort. Results: Across the entire cohort, estimated brain mass deviated by a median 10% between models, with a per-patient median difference in SI of 3.5%. For the SGA group, brain mass deviation was 42%, and per-patient SI deviation 13.7%. In virtual trials, 87-93% of recommended insulin rates were equal or slightly reduced (δ<0.16mU/h) under the head circumference method, while glycaemic control outcomes showed little change. Conclusion: The results suggest that body weight methods are not as accurate as head circumference methods. Head circumference-based estimates may offer improved modelling accuracy and a small reduction in insulin administration, particularly for SGA infants. © 2014 Elsevier Ireland Ltd
P-rex1 cooperates with PDGFRβ to drive cellular migration in 3D microenvironments
Expression of the Rac-guanine nucleotide exchange factor (RacGEF), P-Rex1 is a key determinant of progression to metastasis in a number of human cancers. In accordance with this proposed role in cancer cell invasion and metastasis, we find that ectopic expression of P-Rex1 in an immortalised human fibroblast cell line is sufficient to drive multiple migratory and invasive phenotypes. The invasive phenotype is greatly enhanced by the presence of a gradient of serum or platelet-derived growth factor, and is dependent upon the expression of functional PDGF receptor β. Consistently, the invasiveness of WM852 melanoma cells, which endogenously express P-Rex1 and PDGFRβ, is opposed by siRNA of either of these proteins. Furthermore, the current model of P-Rex1 activation is advanced through demonstration of P-Rex1 and PDGFRβ as components of the same macromolecular complex. These data suggest that P-Rex1 has an influence on physiological migratory processes, such as invasion of cancer cells, both through effects upon classical Rac1-driven motility and a novel association with RTK signalling complexes
Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
We use neutron scattering to study the structural and magnetic phase
transitions in the iron pnictides CeFeAsO1-xFx as the system is tuned from a
semimetal to a high-transition-temperature (high-Tc) superconductor through
Fluorine (F) doping x. In the undoped state, CeFeAsO develops a structural
lattice distortion followed by a stripe like commensurate antiferromagnetic
order with decreasing temperature. With increasing Fluorine doping, the
structural phase transition decreases gradually while the antiferromagnetic
order is suppressed before the appearance of superconductivity, resulting an
electronic phase diagram remarkably similar to that of the high-Tc copper
oxides. Comparison of the structural evolution of CeFeAsO1-xFx with other
Fe-based superconductors reveals that the effective electronic band width
decreases systematically for materials with higher Tc. The results suggest that
electron correlation effects are important for the mechanism of high-Tc
superconductivity in these Fe pnictides.Comment: 19 pages, 5 figure
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