1,655 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
Portuguese category norms for children
This study presents Portuguese category norms for children of three different age groups: preschoolers (3- to
4-year-olds), second graders (7- to 8-year-olds), and preadolescents (11- to 12-year-olds). Three hundred Portuguese
children (100 in each group) completed an exemplar-generation task. Preschoolers generated exemplars
for 13 categories, second graders generated exemplars for 17 categories, and preadolescents generated exemplars
for 21 categories. For each group, responses within each category were organized according to frequency of
production in order to derive exemplar-production norms for sets of tested categories. The results also included
information about the number of responses and exemplars, idiosyncratic and inappropriate responses, and commonality
and diversity indexes for all the categories. A comparison of these children’s norms with the Portuguese
adult norms was also presented. The full set of norms may be downloaded from www.psychonomic.org/archive
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)
Prefrontal dopamine and the dynamic control of human long-term memory
Dopaminergic projections to the prefrontal cortex support higher-order cognitive functions, and are critically involved in many psychiatric disorders that involve memory deficits, including schizophrenia. The role of prefrontal dopamine in long-term memory, however, is still unclear. We used an imaging genetics approach to examine the hypothesis that dopamine availability in the prefrontal cortex selectively affects the ability to suppress interfering memories. Human participants were scanned via functional magnetic resonance imaging while practicing retrieval of previously studied target information in the face of interference from previously studied non-target information. This retrieval practice (RP) rendered the non-target information less retrievable on a later final test—a phenomenon known as retrieval-induced forgetting (RIF). In total, 54 participants were genotyped for the catechol-O-methyltransferase (COMT) Val108/158Met polymorphism. The COMT Val108/158Met genotype showed a selective and linear gene-dose effect on RIF, with the Met allele, which leads to higher prefrontal dopamine availability, being associated with greater RIF. Mirroring the behavioral pattern, the functional magnetic resonance imaging data revealed that Met allele carriers, compared with Val allele carriers, showed a greater response reduction in inhibitory control areas of the right inferior frontal cortex during RP, suggesting that they more efficiently reduced interference. These data support the hypothesis that the cortical dopaminergic system is centrally involved in the dynamic control of human long-term memory, supporting efficient remembering via the adaptive suppression of interfering memories
Verbal short-term memory deficits in Down syndrome: phonological, semantic, or both?
The current study examined the phonological and semantic contributions to the verbal short-term memory (VSTM) deficit in Down syndrome (DS) by experimentally manipulating the phonological and semantic demands of VSTM tasks. The performance of 18 individuals with DS (ages 11–25) and 18 typically developing children (ages 3–10) matched pairwise on receptive vocabulary and gender was compared on four VSTM tasks, two tapping phonological VSTM (phonological similarity, nonword discrimination) and two tapping semantic VSTM (semantic category, semantic proactive interference). Group by condition interactions were found on the two phonological VSTM tasks (suggesting less sensitivity to the phonological qualities of words in DS), but not on the two semantic VSTM tasks. These findings suggest that a phonological weakness contributes to the VSTM deficit in DS. These results are discussed in relation to the DS neuropsychological and neuroanatomical phenotype
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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
- …