282 research outputs found
Optical Spectra of SNR Candidates in NGC 300
We present moderate-resolution (<5A) long-slit optical spectra of 51 nebular
objects in the nearby Sculptor Group galaxy NGC 300 obtained with the 2.3 meter
Advanced Technology Telescope at Siding Spring Observatory, Australia. Adopting
the criterion of [SII]/Ha>=0.4 to confirm supernova remnants (SNRs) from
optical spectra, we find that of 28 objects previously proposed as SNRs from
optical observations, 22 meet this criterion with six showing [SII]/Ha of less
than 0.4. Of 27 objects suggested as SNRs from radio data, four are associated
with the 28 previously proposed SNRs. Of these four, three (included in the 22
above) meet the criterion. In all, 22 of the 51 nebular objects meet the
[SII]/Ha criterion as SNRs while the nature of the remaining 29 objects remains
undetermined by these observations.Comment: Accepted for publication in Astrophysics & Space Scienc
Theoretical investigations of a highly mismatched interface: the case of SiC/Si(001)
Using first principles, classical potentials, and elasticity theory, we
investigated the structure of a semiconductor/semiconductor interface with a
high lattice mismatch, SiC/Si(001). Among several tested possible
configurations, a heterostructure with (i) a misfit dislocation network pinned
at the interface and (ii) reconstructed dislocation cores with a carbon
substoichiometry is found to be the most stable one. The importance of the slab
approximation in first-principles calculations is discussed and estimated by
combining classical potential techniques and elasticity theory. For the most
stable configuration, an estimate of the interface energy is given. Finally,
the electronic structure is investigated and discussed in relation with the
dislocation array structure. Interface states, localized in the heterostructure
gap and located on dislocation cores, are identified
Charge-Symmetry Breaking and the Two-Pion-Exchange Two-Nucleon Interaction
Charge-symmetry breaking in the nucleon-nucleon force is investigated within
an effective field theory, using a classification of isospin-violating
interactions based on power-counting arguments. The relevant
charge-symmetry-breaking interactions corresponding to the first two orders in
the power counting are discussed, including their effects on the 3He-3H
binding-energy difference. The static charge-symmetry-breaking potential linear
in the nucleon-mass difference is constructed using chiral perturbation theory.
Explicit formulae in momentum and configuration spaces are presented. The
present work completes previously obtained results.Comment: 15 pages, 2 figure
Universal Correlations in Pion-less EFT with the Resonating Group Model: Three and Four Nucleons
The Effective Field Theory "without pions" at next-to-leading order is used
to analyze universal bound state and scattering properties of the 3- and
4-nucleon system. Results of a variety of phase shift equivalent nuclear
potentials are presented for bound state properties of 3H and 4He, and for the
singlet S-wave 3He-neutron scattering length a_0(3He-n). The calculations are
performed with the Refined Resonating Group Method and include a full treatment
of the Coulomb interaction and the leading-order 3-nucleon interaction. The
results compare favorably with data and values from AV18(+UIX) model
calculations. A new correlation between a_0(3He-n) and the 3H binding energy is
found. Furthermore, we confirm at next-to-leading order the correlations,
already found at leading-order, between the 3H binding energy and the 3H charge
radius, and the Tjon line. With the 3H binding energy as input, we get
predictions of the Effective Field Theory "without pions" at next-to-leading
order for the root mean square charge radius of 3H of (1.6\pm 0.2) fm, for the
4He binding energy of (28\pm 2.5) MeV, and for Re(a_0(3He-n)) of (7.5\pm
0.6)fm. Including the Coulomb interaction, the splitting in binding energy
between 3H and 3He is found to be (0.66\pm 0.03) MeV. The discrepancy to data
of (0.10\mp 0.03) MeV is model independently attributed to higher order charge
independence breaking interactions. We also demonstrate that different results
for the same observable stem from higher order effects, and carefully assess
that numerical uncertainties are negligible. Our results demonstrate the
convergence and usefulness of the pion-less theory at next-to-leading order in
the 4He channel. We conclude that no 4-nucleon interaction is needed to
renormalize the theory at next-to-leading order in the 4-nucleon sector.Comment: 24 pages revtex4, including 8 figures as .eps files embedded with
includegraphicx, leading-order results added, calculations include the LO
three-nucleon interaction explicitly, comment on Wigner bound added, minor
modification
Magnet-retained auricular prosthesis with an implant-supported composite bar: a clinical report
The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour
Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect
Clinical and pathological study of an outbreak of obstructive urolithiasis in feedlot cattle in southern Brazil
On the stability and uniqueness of the flow of a fluid through a porous medium
© 2016, The Author(s). In this short note, we study the stability of flows of a fluid through porous media that satisfies a generalization of Brinkman’s equation to include inertial effects. Such flows could have relevance to enhanced oil recovery and also to the flow of dense liquids through porous media. In any event, one cannot ignore the fact that flows through porous media are inherently unsteady, and thus, at least a part of the inertial term needs to be retained in many situations. We study the stability of the rest state and find it to be asymptotically stable. Next, we study the stability of a base flow and find that the flow is asymptotically stable, provided the base flow is sufficiently slow. Finally, we establish results concerning the uniqueness of the flow under appropriate conditions, and present some corresponding numerical results
Human vaccination against Plasmodium vivax Duffy-binding protein induces strain-transcending antibodies
BACKGROUND. Plasmodium vivax is the most widespread human malaria geographically; however, no effective vaccine exists. Red blood cell invasion by the P. vivax merozoite depends on an interaction between the Duffy antigen receptor for chemokines (DARC) and region II of the parasite’s Duffy-binding protein (PvDBP_RII). Naturally acquired binding-inhibitory antibodies against this interaction associate with clinical immunity, but it is unknown whether these responses can be induced by human vaccination.
METHODS. Safety and immunogenicity of replication-deficient chimpanzee adenovirus serotype 63 (ChAd63) and modified vaccinia virus Ankara (MVA) viral vectored vaccines targeting PvDBP_RII (Salvador I strain) were assessed in an open-label dose-escalation phase Ia study in 24 healthy UK adults. Vaccines were delivered by the intramuscular route in a ChAd63-MVA heterologous prime-boost regimen using an 8-week interval.
RESULTS. Both vaccines were well tolerated and demonstrated a favorable safety profile in malaria-naive adults. PvDBP_RII–specific ex-vivo IFN-γ T cell, antibody-secreting cell, memory B cell, and serum IgG responses were observed after the MVA boost immunization. Vaccine-induced antibodies inhibited the binding of vaccine homologous and heterologous variants of recombinant PvDBP_RII to the DARC receptor, with median 50% binding-inhibition titers greater than 1:100.
CONCLUSION. We have demonstrated for the first time to our knowledge that strain-transcending antibodies can be induced against the PvDBP_RII antigen by vaccination in humans. These vaccine candidates warrant further clinical evaluation of efficacy against the blood-stage P. vivax parasite
A monovalent chimpanzee adenovirus Ebola vaccine boosted with MVA
BACKGROUND
The West African outbreak of Ebola virus disease that peaked in 2014 has caused more than 11,000 deaths. The development of an effective Ebola vaccine is a priority for control of a future outbreak.
METHODS
In this phase 1 study, we administered a single dose of the chimpanzee adenovirus 3 (ChAd3) vaccine encoding the surface glycoprotein of Zaire ebolavirus (ZEBOV) to 60 healthy adult volunteers in Oxford, United Kingdom. The vaccine was administered in three dose levels — 1×1010 viral particles, 2.5×1010 viral particles, and 5×1010 viral particles — with 20 participants in each group. We then assessed the effect of adding a booster dose of a modified vaccinia Ankara (MVA) strain, encoding the same Ebola virus glyco- protein, in 30 of the 60 participants and evaluated a reduced prime–boost interval in another 16 participants. We also compared antibody responses to inactivated whole Ebola virus virions and neutralizing antibody activity with those observed in phase 1 studies of a recombinant vesicular stomatitis virus–based vaccine expressing a ZEBOV glycoprotein (rVSV-ZEBOV) to determine relative potency and assess durability.
RESULTS
No safety concerns were identified at any of the dose levels studied. Four weeks after immunization with the ChAd3 vaccine, ZEBOV-specific antibody responses were similar to those induced by rVSV-ZEBOV vaccination, with a geometric mean titer of 752 and 921, respectively. ZEBOV neutralization activity was also similar with the two vaccines (geo- metric mean titer, 14.9 and 22.2, respectively). Boosting with the MVA vector increased virus-specific antibodies by a factor of 12 (geometric mean titer, 9007) and increased glycoprotein-specific CD8+ T cells by a factor of 5. Significant increases in neutralizing antibodies were seen after boosting in all 30 participants (geometric mean titer, 139; P<0.001). Virus-specific antibody responses in participants primed with ChAd3 remained positive 6 months after vaccination (geometric mean titer, 758) but were significantly higher in those who had received the MVA booster (geometric mean titer, 1750; P<0.001).
CONCLUSIONS
The ChAd3 vaccine boosted with MVA elicited B-cell and T-cell immune responses to ZEBOV that were superior to those induced by the ChAd3 vaccine alone. (Funded by the Wellcome Trust and others; ClinicalTrials.gov number, NCT02240875.
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