27 research outputs found
The Flavor Asymmetry of the Light Quark Sea from Semi-inclusive Deep-inelastic Scattering
The flavor asymmetry of the light quark sea of the nucleon is determined in
the kinematic range 0.02<x<0.3 and 1 GeV^2<Q^2<10 GeV^2, for the first time
from semi-inclusive deep-inelastic scattering. The quantity
(dbar(x)-ubar(x))/(u(x)-d(x)) is derived from a relationship between the yields
of positive and negative pions from unpolarized hydrogen and deuterium targets.
The flavor asymmetry dbar-ubar is found to be non-zero and x dependent, showing
an excess of dbar over ubar quarks in the proton.Comment: 7 Pages, 2 figures, RevTeX format; slight revision in text, small
change in extraction of dbar-ubar and comparison with a high q2
parameterizatio
Europe
The foregoing conclusions are broadly consistent with those expressed in the IPCC Special Report on Regional Impacts of Climate Change (1998) and the Second Assessment Report(1996). This survey incorporates much more information than previously reported, corroborating previous conclusions (with which it is broadly consistent) but extending knowledge into other sectors. It is more specific about subregional effects and includes new information concerning adaptive capacity
Measurement of J/Ψ production in pp collisions at √s=7 TeV
The production of J/psi mesons in proton-proton collisions at root s = 7 TeV is studied with the LHCb detector at the LHC. The differential cross-section for prompt J/psi production is measured as a function of the J/psi transverse momentum p(T) and rapidity y in the fiducial region p(T) is an element of [0; 14] GeV/c and y is an element of [2.0; 4.5]. The differential cross-section and fraction of J/psi from b-hadron decays are also measured in the same p(T) and y ranges. The analysis is based on a data sample corresponding to an integrated luminosity of 5.2 pb(-1). The measured cross-sections integrated over the fiducial region are 10.52 +/- 0.04 +/- 1.40(-2.20)(+1.64) mu b for prompt J/psi production and 1.14 +/- 0.01 +/- 0.16 mu b for J/psi from b-hadron decays, where the first uncertainty is statistical and the second systematic. The prompt J/psi production cross-section is obtained assuming no J/psi polarisation and the third error indicates the acceptance uncertainty due to this assumption
Intrinsic motivation and academic performance in school-age children born extremely preterm:The contribution of working memory
Intrinsic motivation is associated with better academic performance. Working memory abilities may contribute to this association, especially in children at risk for learning and academic difficulties such as those born extremely preterm. This study examined whether verbal and visuo-spatial working memory abilities mediate the relationship between intrinsic motivation for school learning (mastery, challenge and curiosity) and academic performance (word reading, spelling and mathematics) in 7-year old extremely preterm or extremely low birth weight children (n = 91). Structural equation modeling revealed verbal short-term memory to mediate associations between aspects of intrinsic motivation and literacy performance. Positive associations between mastery and verbal short-term memory, reading and spelling, and a positive association between challenge and mathematics performance were also identified. These findings highlight potential pathways linking intrinsic motivation for school learning, working memory, and academic achievement in early school-age children at risk of academic impairments. Examination of individual characteristics such as motivation and cognitive skills is important for understanding factors that shape children's learning and performance.L.Pascoe, M.Spencer-Smith, R.Giallo, M.L.Seal, N.Georgiou-Karistianis, C.Nosarti, E.K.Josev, G.Roberts, L.W.Doyle, D.K.Thompson, P.J.Anderso
Differences between liking and wanting signals in the human brain and relations with cognitive dietary restraint and body mass index.
BACKGROUND: Eating behavior is determined, to a significant extent, by the rewarding value of food (ie, liking and wanting). OBJECTIVE: We determined brain regions involved in liking and wanting and related brain signaling to body mass index (BMI; in kg/m(2)) and dietary restraint. DESIGN: Fifteen normal-weight female subjects [mean +/- SEM age: 21.5 +/- 0.4 y; BMI: 22.2 +/- 0.2] completed a food-choice paradigm by using visually displayed food items during functional magnetic resonance imaging (fMRI) scans. Two scans were made as follows: one scan was made in a fasted condition, and one scan was made in a satiated condition. The paradigm discriminated between liking and wanting, and subjects were offered items rated highly for wanting immediately after each scan. Imaging contrasts for high and low liking and wanting were made, and data for regions of interest were extracted. Activation related to liking and wanting, respectively, was determined. Outcomes were correlated to cognitive dietary restraint and BMI. RESULTS: Dietary restraint predicted liking task-related signaling (TRS) in the amygdala, striatum, thalamus, and cingulate cortex (r = -0.5 +/- 0.03, P < 0.00001). In the nucleus accumbens, the premeal liking and wanting TRS and premeal to postmeal liking TRS changes correlated positively with dietary restraint [bilateral average r = 0.6 +/- 0.02, P < 0.04 (Bonferroni corrected)]. BMI and hunger predicted wanting TRS in the hypothalamus and striatum (P < 0.05). Postmeal liking TRS in the striatum, anterior insula, and cingulate cortex and wanting TRS in the striatum predicted the energy intake (liking: r = -0.3 +/- 0.05, P < 0.0001; wanting: r = -0.3 +/- 0.03, P < 0.00001). CONCLUSIONS: Successful dietary restraint was supported by liking TRS from premeal to postmeal in the nucleus accumbens. Reward-related signaling was inversely related to BMI and energy intake, indicating reward deficiency