1,161 research outputs found
Observation of an Excited Bc+ State
Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc∗(2S31)+ state reconstructed without the low-energy photon from the Bc∗(1S31)+→Bc+γ decay following Bc∗(2S31)+→Bc∗(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date
Cognitive Performances Are Selectively Enhanced during Chronic Caloric Restriction or Resveratrol Supplementation in a Primate
Effects of an 18-month treatment with a moderate, chronic caloric restriction (CR) or an oral supplementation with resveratrol (RSV), a potential CR mimetic, on cognitive and motor performances were studied in non-human primates, grey mouse lemurs (Microcebus murinus)
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Measurement of CP observables in the process B <sup>0</sup> → DK <sup>*0</sup> with two- and four-body D decays
Measurements of observables in decays are presented,
where represents a superposition of and states. The
meson is reconstructed in the two-body final states , ,
and , and, for the first time, in the four-body final
states , and .
The analysis uses a sample of neutral mesons produced in proton-proton
collisions, corresponding to an integrated luminosity of 1.0, 2.0 and 1.8 collected with the LHCb detector at centre-of-mass energies of
7, 8 and 13 TeV, respectively. First observations of the decays
and are
obtained. The measured observables are interpreted in terms of the
-violating weak phase
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Updated measurement of time-dependent CP -violating observables in Bs0→J/ψ<sup>K+</sup><sup>K-</sup> decays
The decay-time-dependent asymmetry in
decays is measured using proton-proton collision data, corresponding to an
integrated luminosity of , collected with the LHCb
detector at a centre-of-mass energy of in 2015 and 2016.
Using a sample of approximately 117\,000 signal decays with an invariant mass in the vicinity of the resonance, the -violating
phase is measured, along with the difference in decay widths of the
light and heavy mass eigenstates of the - system,
. The difference of the average and meson
decay widths, , is determined using in addition a sample of
decays. The values obtained are , and , where the first uncertainty is statistical and the
second systematic. These are the most precise single measurements of these
quantities to date and are consistent with expectations based on the Standard
Model and with a previous LHCb analysis of this decay using data recorded at
centre-of-mass energies 7 and 8 TeV. Finally, the results are combined with
recent results from decays obtained using
the same dataset as this analysis, and with previous independent LHCb results
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Observation of the Λb0→χc1 (3872) pK<sup>−</sup> decay
Using proton-proton collision data, collected with the LHCb detector and
corresponding to 1.0, 2.0 and 1.9fb of integrated luminosity at the
centre-of-mass energies of 7, 8, and 13 TeV, respectively, the decay
with is
observed for the first time. The significance of the observed signal is in
excess of seven standard deviations. It is found that of the
decays proceed via the two-body intermediate state
. The~branching fraction with respect to that of
the decay mode, where the
~meson is reconstructed in the final state, is
measured to be: \begin{equation*}
\frac{\Lambda_b^0\to\chi_{c1}(3872)pK^-}{\Lambda_b\to\psi(2S)p K^-} \times
\frac{\mathcal{B}(\chi_{c1} \to J/\psi \pi^+\pi^-)}{\mathcal{B}(\psi(2S)\to
J/\psi \pi^+\pi^-)} = \left(5.4 \pm 1.1 \pm 0.2\right)\times 10^{-2}\,,
\end{equation*} where the first uncertainty is statistical and the second is
systematic
T-Cell Immune Responses Against Env from CRF12_BF and Subtype B HIV-1 Show High Clade-Specificity that Can Be Overridden by Multiclade Immunizations
BACKGROUND: The extreme genetic diversity of the human immunodeficiency virus type 1 (HIV-1) poses a daunting challenge to the generation of an effective AIDS vaccine. In Argentina, the epidemic is characterized by the high prevalence of infections caused by subtype B and BF variants. The aim of this study was to characterize in mice the immunogenic and antigenic properties of the Env protein from CRF12_BF in comparison with clade B, employing prime-boost schemes with the combination of recombinant DNA and vaccinia virus (VV) vectors. METHODOLOGY/PRINCIPAL FINDINGS: As determined by ELISPOT from splenocytes of animals immunized with either EnvBF or EnvB antigens, the majority of the cellular responses to Env were found to be clade-specific. A detailed peptide mapping of the responses reveal that when there is cross-reactivity, there are no amino acid changes in the peptide sequence or were minimal and located at the peptide ends. In those cases, analysis of T cell polifunctionality and affinity indicated no differences with respect to the cellular responses found against the original homologous sequence. Significantly, application of a mixed immunization combining both clades (B and BF) induced a broader cellular response, in which the majority of the peptides targeted after the single clade vaccinations generated a positive response. In this group we could also find significant cellular and humoral responses against the whole gp120 protein from subtype B. CONCLUSIONS/SIGNIFICANCE: This work has characterized for the first time the immunogenic peptides of certain EnvBF regions, involved in T cell responses. It provides evidence that to improve immune responses to HIV there is a need to combine Env antigens from different clades, highlighting the convenience of the inclusion of BF antigens in future vaccines for geographic regions where these HIV variants circulate
IL-12 and GM-CSF in DNA/MVA Immunizations against HIV-1 CRF12_BF Nef Induced T-Cell Responses With an Enhanced Magnitude, Breadth and Quality
In Argentina, the HIV epidemic is characterized by the co-circulation of subtype B and BF recombinant viral variants. Nef is an HIV protein highly variable among subtypes, making it a good tool to study the impact of HIV variability in the vaccine design setting. We have previously reported a specific cellular response against NefBF with low cross-reactivity to NefB in mice. The aim of this work was to analyze whether the co-administration of IL-12 and GM-CSF, using DNA and MVA vaccine vectors, could improve the final cellular response induced. Mice received three DNA priming doses of a plasmid that express NefBF plus DNAs expressing IL-12 and/or GM-CSF. Afterwards, all the groups were boosted with a MVAnefBF dose. The highest increase in the magnitude of the NefBF response, compared to that induced in the control was found in the IL-12 group. Importantly, a response with higher breadth was detected in groups which received IL-12 or GM-CSF, evidenced as an increased frequency of recognition of homologous (BF) and heterologous (B) Nef peptides, as well as a higher number of other Nef peptide pools representing different viral subtypes. However, these improvements were lost when both DNA cytokines were simultaneously administered, as the response was focused against the immunodominant peptide with a detrimental response towards subdominant epitopes. The pattern of cytokines secreted and the specific-T-cell proliferative capacity were improved in IL-12 and IL-12+GM-CSF groups. Importantly IL-12 generated a significant higher T-cell avidity against a B heterologous peptide
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