642 research outputs found
A Multi-Component Prime-Boost Vaccination Regimen with a Consensus MOMP Antigen Enhances Chlamydia trachomatis Clearance
The Supplementary Material for this article can be found online at http://journal.frontiersin.org/article/10.3389/fimmu.2016.00162BACKGROUND: A vaccine for Chlamydia trachomatis is of urgent medical need. We explored bioinformatic approaches to generate an immunogen against C. trachomatis that would induce cross-serovar T-cell responses as (i) CD4(+) T cells have been shown in animal models and human studies to be important in chlamydial protection and (ii) antibody responses may be restrictive and serovar specific.
METHODS: A consensus antigen based on over 1,500 major outer membrane protein (MOMP) sequences provided high epitope coverage against the most prevalent C. trachomatis strains in silico. Having designed the T-cell immunogen, we assessed it for immunogenicity in prime-boost regimens. This consensus MOMP transgene was delivered using plasmid DNA, Human Adenovirus 5 (HuAd5) or modified vaccinia Ankara (MVA) vectors with or without MF59(®) adjuvanted recombinant MOMP protein.
RESULTS: Different regimens induced distinct immune profiles. The DNA-HuAd5-MVA-Protein vaccine regimen induced a cellular response with a Th1-biased serum antibody response, alongside high serum and vaginal MOMP-specific antibodies. This regimen significantly enhanced clearance against intravaginal C. trachomatis serovar D infection in both BALB/c and B6C3F1 mouse strains. This enhanced clearance was shown to be CD4(+) T-cell dependent. Future studies will need to confirm the specificity and precise mechanisms of protection.
CONCLUSION: A C. trachomatis vaccine needs to induce a robust cellular response with broad cross-serovar coverage and a heterologous prime-boost regimen may be an approach to achieve this.AB was funded by the Wellcome Trust. RS was supported by the European Community’s European 7th Framework Program ADITEC (HEALTH-F4-2011-18 280873).info:eu-repo/semantics/publishedVersio
Two-neutron transfer reaction mechanisms in C(He,He)C using a realistic three-body He model
The reaction mechanisms of the two-neutron transfer reaction
C(He,He) have been studied at 30 MeV at the TRIUMF ISAC-II
facility using the SHARC charged-particle detector array. Optical potential
parameters have been extracted from the analysis of the elastic scattering
angular distribution. The new potential has been applied to the study of the
transfer angular distribution to the 2 8.32 MeV state in C, using
a realistic 3-body He model and advanced shell model calculations for the
carbon structure, allowing to calculate the relative contributions of the
simultaneous and sequential two-neutron transfer. The reaction model provides a
good description of the 30 MeV data set and shows that the simultaneous process
is the dominant transfer mechanism. Sensitivity tests of optical potential
parameters show that the final results can be considerably affected by the
choice of optical potentials. A reanalysis of data measured previously at 18
MeV however, is not as well described by the same reaction model, suggesting
that one needs to include higher order effects in the reaction mechanism.Comment: 9 pages, 9 figure
Longitudinal double spin asymmetries in single hadron quasi-real photoproduction at high
We measured the longitudinal double spin asymmetries for single
hadron muo-production off protons and deuterons at photon virtuality <
1(GeV/) for transverse hadron momenta in the range 0.7
GeV/ to 4 GeV/ . They were determined using COMPASS data taken
with a polarised muon beam of 160 GeV/ or 200 GeV/ impinging on
polarised or targets. The experimental
asymmetries are compared to next-to-leading order pQCD calculations, and are
sensitive to the gluon polarisation inside the nucleon in the range
of the nucleon momentum fraction carried by gluons
Interplay among transversity induced asymmetries in hadron leptoproduction
In the fragmentation of a transversely polarized quark several left-right
asymmetries are possible for the hadrons in the jet. When only one unpolarized
hadron is selected, it exhibits an azimuthal modulation known as Collins
effect. When a pair of oppositely charged hadrons is observed, three
asymmetries can be considered, a di-hadron asymmetry and two single hadron
asymmetries. In lepton deep inelastic scattering on transversely polarized
nucleons all these asymmetries are coupled with the transversity distribution.
From the high statistics COMPASS data on oppositely charged hadron-pair
production we have investigated for the first time the dependence of these
three asymmetries on the difference of the azimuthal angles of the two hadrons.
The similarity of transversity induced single and di-hadron asymmetries is
discussed. A new analysis of the data allows to establish quantitative
relationships among them, providing for the first time strong experimental
indication that the underlying fragmentation mechanisms are all driven by a
common physical process.Comment: 6 figure
Interplay among transversity induced asymmetries in hadron leptoproduction
In the fragmentation of a transversely polarized quark several left-right
asymmetries are possible for the hadrons in the jet. When only one unpolarized
hadron is selected, it exhibits an azimuthal modulation known as Collins
effect. When a pair of oppositely charged hadrons is observed, three
asymmetries can be considered, a di-hadron asymmetry and two single hadron
asymmetries. In lepton deep inelastic scattering on transversely polarized
nucleons all these asymmetries are coupled with the transversity distribution.
From the high statistics COMPASS data on oppositely charged hadron-pair
production we have investigated for the first time the dependence of these
three asymmetries on the difference of the azimuthal angles of the two hadrons.
The similarity of transversity induced single and di-hadron asymmetries is
discussed. A new analysis of the data allows to establish quantitative
relationships among them, providing for the first time strong experimental
indication that the underlying fragmentation mechanisms are all driven by a
common physical process.Comment: 6 figure
Spectroscopic and Structural Probing of Excited-State Molecular Dynamics with Time-Resolved Photoelectron Spectroscopy and Ultrafast Electron Diffraction
Pump-probe measurements aim to capture the motion of electrons and nuclei on their natural timescales (femtoseconds to attoseconds) as chemical and physical transformations take place, effectively making molecular movies with short light pulses. However, the quantum dynamics of interest are filtered by the coordinate-dependent matrix elements of the chosen experimental observable. Thus, it is only through a combination of experimental measurements and theoretical calculations that one can gain insight into the internal dynamics. Here, we report on a combination of structural (relativistic ultrafast electron diffraction, or UED) and spectroscopic (time-resolved photoelectron spectroscopy, or TRPES) measurements to follow the coupled electronic and nuclear dynamics involved in the internal conversion and photodissociation of the polyatomic molecule, diiodomethane (CH2I2). While UED directly probes the 3D nuclear dynamics, TRPES only serves as an indirect probe of nuclear dynamics via Franck-Condon factors, but it is sensitive to electronic energies and configurations, via Koopmans\u27 correlations and photoelectron angular distributions. These two measurements are interpreted with trajectory surface hopping calculations, which are capable of simulating the observables for both measurements from the same dynamics calculations. The measurements highlight the nonlocal dynamics captured by different groups of trajectories in the calculations. For the first time, both UED and TRPES are combined with theory capable of calculating the observables in both cases, yielding a direct view of the structural and nonadiabatic dynamics involved
The Spin Structure Function of the Proton and a Test of the Bjorken Sum Rule
New results for the double spin asymmetry and the proton
longitudinal spin structure function are presented. They were
obtained by the COMPASS collaboration using polarised 200 GeV muons scattered
off a longitudinally polarised NH target. The data were collected in 2011
and complement those recorded in 2007 at 160\,GeV, in particular at lower
values of . They improve the statistical precision of by
about a factor of two in the region . A next-to-leading order
QCD fit to the world data is performed. It leads to a new determination
of the quark spin contribution to the nucleon spin, ranging
from 0.26 to 0.36, and to a re-evaluation of the first moment of .
The uncertainty of is mostly due to the large uncertainty in
the present determinations of the gluon helicity distribution. A new evaluation
of the Bjorken sum rule based on the COMPASS results for the non-singlet
structure function yields as ratio of the axial and
vector coupling constants , which validates the sum rule to an accuracy of about
9\%.Comment: 19 pages, 8 figures and table
Resonance Production and S-wave in at 190 GeV/c
The COMPASS collaboration has collected the currently largest data set on
diffractively produced final states using a negative pion
beam of 190 GeV/c momentum impinging on a stationary proton target. This data
set allows for a systematic partial-wave analysis in 100 bins of three-pion
mass, GeV/c , and in 11 bins of the reduced
four-momentum transfer squared, (GeV/c) . This
two-dimensional analysis offers sensitivity to genuine one-step resonance
production, i.e. the production of a state followed by its decay, as well as to
more complex dynamical effects in nonresonant production. In this paper,
we present detailed studies on selected partial waves with , , , , and . In these waves, we observe
the well-known ground-state mesons as well as a new narrow axial-vector meson
decaying into . In addition, we present the results
of a novel method to extract the amplitude of the subsystem with
in various partial waves from the
data. Evidence is found for correlation of the and
appearing as intermediate isobars in the decay of the known
and .Comment: 96 page
Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data
Using a novel analysis technique, the gluon polarisation in the nucleon is
re-evaluated using the longitudinal double-spin asymmetry measured in the cross
section of semi-inclusive single-hadron muoproduction with photon virtuality
. The data were obtained by the COMPASS experiment at
CERN using a 160 GeV/ polarised muon beam impinging on a polarised LiD
target. By analysing the full range in hadron transverse momentum ,
the different -dependences of the underlying processes are separated
using a neural-network approach. In the absence of pQCD calculations at
next-to-leading order in the selected kinematic domain, the gluon polarisation
is evaluated at leading order in pQCD at a hard scale of . It is determined in three intervals
of the nucleon momentum fraction carried by gluons, , covering the
range ~ and does not exhibit a significant
dependence on . The average over the three intervals, at
, suggests that the gluon polarisation
is positive in the measured range.Comment: 14 pages, 6 figure
Multiplicities of charged pions and unidentified charged hadrons from deep-inelastic scattering of muons off an isoscalar target
Multiplicities of charged pions and unidentified hadrons produced in
deep-inelastic scattering were measured in bins of the Bjorken scaling variable
, the relative virtual-photon energy and the relative hadron energy .
Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and
an isoscalar target (LiD). They cover the kinematic domain in the photon
virtuality > 1(GeV/c, , and . In addition, a leading-order pQCD analysis was performed using the
pion multiplicity results to extract quark fragmentation functions
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