8,509 research outputs found
Effect of Contrast-Enhanced Echocardiograms on the Prognosis of Infective Endocarditis
Objective - Infective endocarditis (IE) is an infectious disease of the cardiac valves where bacteria colonize the valves; typically, via the formation of vegetations. Recent research has shown that the microbubbles in a contrast-enhanced ultrasound (CEUS) examination can move and dislodge bacterial vegetations in vitro. This study investigated whether CEUS resulted in faster resolution of IE in vivo by dislodging the vegetations.
Methods - This IRB approved retrospective study reviewed 36 patients who were diagnosed with IE via echocardiography. Data was sourced from patients within the Jefferson University Hospital’s Cardiology EMR system by searching for contrast and vegetation from January 1st, 2013 – January 1st, 2018. Fifteen patients were not given contrast, whereas 21 patients were given contrast via agitated saline (n=16) or an ultrasound contrast agent (n=5). All patients received an echocardiogram after blood cultures confirmed an infection, but before resolution of infection (defined by negative blood cultures). A student’s t-test was used for analyses.
Results - The study population was heterogeneous in terms of sex (67.5% male) and race (70% Caucasian, 25% African American, and 5% Asian), with an average age of 51±20 years, and an average BMI of 29.65±7.43 in the contrast group and 27.67±3.16 in the non-contrast group (p=0.37). Following ultrasound, no patients had documented stroke, pulmonary embolism, or systemic blood clot, which physicians could have attributed to a thrombus resulting from dislodging of bacterial vegetation. Overall, blood cultures did not clear faster in patients receiving CEUS compared to those undergoing standard echocardiography, (2.63±2.69 days vs. 1.34 ±1.11 days, p=0.09). CEUS also did not shorten the admission length in patients with IE, (16.9±7.7 days vs. 19.9±12.1 days; p=0.36).
Conclusion - Based on this limited sample size, patients who underwent CEUS did not have a different prognosis when compared to patients who received a non-contrast echocardiogram
A symmetry adapted approach to vibrational excitations in atomic clusters
An algebraic method especially suited to describe strongly anharmonic
vibrational spectra in molecules may be an appropriate framework to study
vibrational spectra of Na clusters, where nearly flat potential energy
surfaces and the appearance of close lying isomers have been reported. As an
illustration we describe the model and apply it to the Be, H, Be
and Na clusters.Comment: 8 pages with 2 tables, invited talk at `Atomic Nuclei & Metallic
Clusters: Finite Many-Fermion Systems', Prague, Czech Republic, September
1-5, 199
Comment on ``Boson-realization model for the vibrational spectra of tetrahedral molecules''
An algebraic model in terms of a local harmonic boson realization was
recently proposed to study molecular vibrational spectra [Zhong-Qi Ma et al.,
Phys. Rev. A 53, 2173 (1996)]. Because of the local nature of the bosons the
model has to deal with spurious degrees of freedom. An approach to eliminate
the latter from both the Hamiltonian and the basis was suggested. We show that
this procedure does not remove all spurious components from the Hamiltonian and
leads to a restricted set of interactions. We then propose a scheme in which
the physical Hamiltonian can be systematically constructed up to any order
without the need of imposing conditions on its matrix elements. In addition, we
show that this scheme corresponds to the harmonic limit of a symmetry adapted
algebraic approach based on U(2) algebras.Comment: 9 pages Revtex, submitted February 199
A general algebraic model for molecular vibrational spectroscopy
We introduce the Anharmonic Oscillator Symmetry Model to describe vibrational
excitations in molecular systems exhibiting high degree of symmetry. A
systematic procedure is proposed to establish the relation between the
algebraic and configuration space formulations, leading to new interactions in
the algebraic model. This approach incorporates the full power of group
theoretical techniques and provides reliable spectroscopic predictions. We
illustrate the method for the case of -triatomic molecules.Comment: 35 pages TEX, submitted to Annals of Physics (N.Y.
A symmetry-adapted algebraic approach to molecular spectroscopy
We apply a symmetry-adapted algebraic model to the vibrational excitations in
D_3h and T_d molecules. A systematic procedure is used to establish the
relation between the algebraic and configuration space formulations. In this
way we have identified interaction terms that were absent in previous
formulations of the vibron model. The inclusion of these new interactions leads
to reliable spectroscopic predictions. We illustrate the method for the D_3h
triatomic molecules, H_3^+, Be_3 and Na_3, and the T_d molecules, Be_4 and
CH_4.Comment: 16 pages with 4 tables, invited talk at `Symmetries in Science IX',
August 6-10, 199
Radiative capture reaction for Ne formation within a full three-body model
Background: The breakout from the hot Carbon-Nitrogen-Oxigen (CNO) cycles can
trigger the rp-process in type I x-ray bursts. In this environment, a
competition between and the
two-proton capture reaction is
expected.
Purpose: Determine the three-body radiative capture reaction rate for
formation including sequential and direct, resonant and
non-resonant contributions on an equal footing.
Method: Two different discretization methods have been applied to generate
Ne states in a full three-body model: the analytical transformed
harmonic oscillator method and the hyperspherical adiabatic expansion method.
The binary --O interaction has been adjusted to reproduce the known
spectrum of the unbound F nucleus. The dominant contributions to
the reaction rate have been
calculated from the inverse photodissociation process.
Results: Three-body calculations provide a reliable description of Ne
states. The agreement with the available experimental data on Ne is
discussed. It is shown that the
reaction rates computed within the two methods agree in a broad range of
temperatures. The present calculations are compared with a previous theoretical
estimation of the reaction rate.
Conclusions: It is found that the full three-body model provides a reaction
rate several orders of magnitude larger than the only previous estimation. The
implications for the rp-process in type I x-ray bursts should be investigated.Comment: 10 pages, 10 figures. Corrected versio
Evidence of strong dynamic core excitation in C resonant break-up
The resonant break-up of C on protons measured at RIKEN [Phys. Lett. B
660, 320 (2008)] is analyzed in terms of a valence-core model for C
including possible core excitations. The analysis of the angular distribution
of a prominent peak appearing in the relative-energy spectrum could be well
described with this model and is consistent with the previous assignment of
for this state. Inclusion of core-excitation effects are found to be
essential to give the correct magnitude of the cross section for this state. By
contrast, the calculation assuming an inert C core is found to largely
underestimate the data.Comment: 5 pages, 2 figures, to be submitte
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