3,903 research outputs found
Language brain representation in bilinguals with different age of appropriation and proficiency of the second language: A meta-analysis of functional imaging studies
Language representation in the bilingual brain is the result of many factors, of which age of appropriation (AoA) and proficiency of the second language (L2) are probably the most studied. Many studies indeed compare early and late bilinguals, although it is not yet clear what the role of the so-called critical period in L2 appropriation is. In this study, we carried out coordinate-based meta-analyses to address this issue and to inspect the role of proficiency in addition to that of AoA. After the preliminary inspection of the early (also very early) and late bilinguals\u2019 language networks, we explored the specific activations associated with each language and compared them within and between the groups. Results confirmed that the L2 language brain representation was wider than that associated with L1. This was observed regardless of AoA, although differences were more relevant in the late bilinguals\u2019 group. In particular, L2 entailed a greater enrollment of the brain areas devoted to the executive functions, and this was also observed in proficient bilinguals. The early bilinguals displayed many activation clusters as well, which also included the areas involved in cognitive control. Interestingly, these regions activated even in L1 of both early and late bilingual groups, although less consistently. Overall, these findings suggest that bilinguals in general are constantly subjected to cognitive effort to monitor and regulate the language use, although early AoA and high proficiency are likely to reduce this
Understanding Body Language Does Not Require Matching the Body's Egocentric Map to Body Posture: A Brain Activation fMRI Study
Body language (BL) is a type of nonverbal communication in which the body communicates the message. We contrasted participants' cognitive processing of body representations or meanings versus body positions. Participants (N\u2009=\u200920) were shown pictures depicting body postures and were instructed to focus on their meaning (BL) or on the position of a body part relative to the position of another part (body structural description [BSD]). We examined activation in brain areas related to the two types of body representation\u2014body schema and BSD\u2014as modulated by the two tasks. We presumed that if understanding BL triggers embodiment of body posture, a matching procedure between the egocentric map coding the position of one's body segments in space and time should occur. We found that BL (vs. BSD) differentially activated the angular gyrus bilaterally, the anterior middle temporal gyrus, the temporal pole, and the right superior temporal gyrus, the inferior frontal gyrus, the superior medial gyrus, and the left superior frontal gyrus. BSD (vs. BL) differentially activated the superior parietal lobule (Area 7A) bilaterally, the posterior inferior temporal gyrus, the middle frontal gyrus, and the left precentral gyrus. Sensorimotor areas were differentially activated by BSD when compared with BL. Inclusive masking showed significant voxels in the superior colliculus and pulvinar, fusiform gyrus, inferior temporal gyrus, superior temporal gyrus, the intraparietal sulcus bilaterally, inferior frontal gyrus bilaterally, and precentral gyrus. These results indicate common brain networks for processing BL and BSD, for which some areas show differentially stronger or weaker processing of one task or the other, with the precuneus and the superior parietal lobule, the intraparietal sulcus, and sensorimotor areas most related to the BSD as activated by the BSD task. In contrast, the parietal operculum, an area related to the body schema, a representation crucial during embodiment of body postures, was not activated for implicit masking or for the differential contrasts
Scale Factor in Double Parton Collisions and Parton Densities in Transverse Space
The scale factor , which characterizes double parton collisions
in high energy hadron interactions, is a direct manifestation of the
distribution of the interacting partons in transverse space, in such a way that
different distributions give rise to different values of in
different double parton collision processes. We work out the value of the scale
factor in a few reactions of interest, in a correlated model of the
multi-parton density of the proton recently proposed.Comment: 10 pages, 2 figure
Double parton distributions in the leading logarithm approximation of perturbative QCD
Recent CDF measurements of the inclusive cross section for a double parton
scattering attach a great importance to any theoretical calculations of
two-particle distribution functions. Using a parton interpretation of the
leading logarithm diagrams of perturbative QCD theory, generalized
Lipatov-Altarelli-Parisi-Dokshitzer equations for the two-parton distributions
are re-obtained. The solutions of these equations are not at all the product of
two single-parton distributions what is usually applied to the current analysis
as ansatz.Comment: 8 pages, LaTe
The Chances to Produce and Detect the b-b-ubar-dbar Tetraquark at LHC
In the LHC collider a significant rate of events with double parton
scattering is expected. This will be the leading mechanism for production of
two b-bbar pairs. We estimate the probability of binding two b quarks into a
diquark and the probability of dressing this diquark into a b-b-ubar-dbar
ISP=01+ tetraquark. Calculations shows that that this bound state of two B
mesons is stable against the strong interaction and has a life time of the
order of ps. We estimate that the production rate at luminosity L=0.1 events
per second will be about 6 tetraquarks per hour or more.Comment: Contributed talk at the XVIII European Conference on Few-Body
Problems in Physics, September 8-14, Bled, Slovenia, 4 pages LaTe
Production and detection of doubly charmed tetraquarks
The feasibility of tetraquark detection is studied. For the cc\bar{u}\bar{d}
tetraquark we show that in present (SELEX, Tevatron, RHIC) and future
facilities (LHCb, ALICE) the production rate is promising and we propose some
detectable decay channels.Comment: 6 pages, 5 figure
Double parton scatterings in b-quark pairs production at the LHC
A sizable rate of events where two pairs of b-quarks are produced
contemporarily is foreseen at the CERN LHC, as a consequence of the large
parton luminosity. At very high energies both single and the double parton
scatterings contribute to the process, the latter mechanisms, although power
suppressed, giving the dominant contribution to the integrated cross section.Comment: 17 pages, 6 figure
Same-sign W pair production as a probe of double parton scattering at the LHC
We study the production of same-sign W boson pairs at the LHC in double
parton interactions. Compared with simple factorised double parton
distributions (dPDFs), we show that the recently developed dPDFs, GS09, lead to
non-trivial kinematic correlations between the W bosons. A numerical study of
the prospects for observing this process using same-sign dilepton signatures,
including same-sign WWjj, di-boson and heavy flavour backgrounds, at 14 TeV
centre-of-mass energy is then performed. It is shown that a small excess of
same-sign dilepton events from double parton scattering over a background
dominated by single scattering WZ(gamma*) production could be observed at the
LHC.Comment: 14 pages, 8 figures. Added references, slight changes in the text
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