831 research outputs found
What is not working in working memory of children with literacy disorders? Evidence from a three-year-longitudinal study
The goals of this study were to explore the deficits in working memory associated with literacy disorders (i.e. developmental disorders of reading and/or spelling) and the developmental trajectories of these working memory deficits. The performance of 28 children with literacy disorders was compared to a non-disabled control group with the same group size at five bi-annual times of measurement in a three-year-longitudinal study beginning at the end of primary school (9.5 years of age). Storage capacity and central-executive working memory were assessed in phonological and visual-spatial modalities, the latter under static and dynamic conditions. Overall, children with literacy disorders were outperformed by their typical developing peers in all phonological and in dynamic visual-spatial storage and central-executive tasks except for the static visual-spatial storage task. Results at single times of measurement revealed that the most consistent deficit was found in the storage capacity of the phonological loop. An additional central-executive impairment is supported by low backward spans. The causes for output deficits in dynamic visual-spatial tasks and good performance under static visual-spatial condition are discussed.(DIPF/Orig.
The whole and its parts : why and how to disentangle plant communities and synusiae in vegetation classification
Most plant communities consist of different structural and ecological subsets, ranging from cryptogams to different tree layers. The completeness and approach with which these subsets are sampled have implications for vegetation classification. Non‐vascular plants are often omitted or sometimes treated separately, referring to their assemblages as “synusiae” (e.g. epiphytes on bark, saxicolous species on rocks). The distinction of complete plant communities (phytocoenoses or holocoenoses) from their parts (synusiae or merocoenoses) is crucial to avoid logical problems and inconsistencies of the resulting classification systems. We here describe theoretical differences between the phytocoenosis as a whole and its parts, and outline consequences of this distinction for practise and terminology in vegetation classification. To implement a clearer separation, we call for modifications of the International Code of Phytosociological Nomenclature and the EuroVegChecklist. We believe that these steps will make vegetation classification systems better applicable and raise the recognition of the importance of non‐vascular plants in the vegetation as well as their interplay with vascular plants
Beneficial effects of acute high-intensity exercise on electrophysiological indices of attention processes in young adult men
This is the final version. Available on open access from Elsevier via the DOI in this recordBackground: Emerging research suggests that a single bout of aerobic exercise can improve cognition, brain function and psychological health. Our aim was to examine the effects of high-intensity exercise on cognitive-performance and brain measures of attention, inhibition and performance-monitoring across a test-battery of three cognitive tasks. Method: Using a randomised cross-over design, 29 young men completed three successive cognitive tasks (Cued Continuous Performance Task [CPT-OX]; Eriksen Flanker Task; four-choice reaction-time task [Fast Task]) with simultaneous electroencephalogram (EEG) recording before and after a 20-min high-intensity cycling exercise and resting control session. Cognitive-performance measures, EEG power and event-related potential measures, were obtained during the tasks. Random-intercept linear models were used to investigate the effects of exercise, compared to rest, on outcomes. Results: A single bout of exercise significantly (p < 0.05) increased the amplitude of the event-related potential Go P3, but had no effect on the contingent negative variation (CNV), Cue P3 or NoGo P3, during the CPT-OX. Delta power, recorded during the CPT-OX, also significantly increased after exercise, whereas there was no effect on cognitive-performance in this task. Exercise did not influence any cognitive-performance or brain measures in the subsequent Flanker or Fast Tasks. Conclusion: Acute high-intensity exercise improves brain-indices reflecting executive and sustained attention during task performance (Go P3 and delta activity), in the CPT-OX, but not anticipatory attention (Cue P3 and CNV) or response inhibition (NoGo P3) in young-adult men. Exercise had no effect on cognitive-performance or brain measures in the subsequent Flanker and Fast tasks, which may potentially be explained by the time delay after exercise.Medical Research Council (MRC)National Institute for Health Research (NIHR
Dynamical approach to fusion-fission process in superheavy mass region
In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes i
Systematic study of quasifission characteristics and timescales in heavy element formation reactions
Superheavy elements can only be created in the laboratory by the fusion of two massive nuclei. Mass-angle distributions give the most direct information on the characteristics and time scales of quasifission, the major competitor to fusion in these reactions. The systematics of 42 mass-angle distributions provide information on the global characteristics of quasifission. Deviations from the systematics reveal the major role played by the nuclear structure of the two colliding nuclei in determining the reaction outcome, and in hindering or favouring heavy element production.The authors acknowledge operations support for the ANU Heavy Ion Accelerator
Facility from NCRIS, and support from Dr. N. Lobanov and Dr. T.
Kibedi and the ANU Heavy Ion Accelerator Facility staff in operating the
Linac. Financial support from ARC grants DP130101569, DP140101337,
FL110100098, FT120100760 and DE140100784 is acknowledged
Deuteron and antideuteron production in Au+Au collisions at sqrt(s_NN)=200 GeV
The production of deuterons and antideuterons in the transverse momentum
range 1.1 < p_T < 4.3 GeV/c at mid-rapidity in Au + Au collisions at
sqrt(s_NN)=200 GeV has been studied by the PHENIX experiment at RHIC. A
coalescence analysis comparing the deuteron and antideuteron spectra with those
of protons and antiprotons, has been performed. The coalescence probability is
equal for both deuterons and antideuterons and increases as a function of p_T,
which is consistent with an expanding collision zone. Comparing (anti)proton
yields p_bar/p = 0.73 +/- 0.01, with (anti)deuteron yields: d_bar/d = 0.47 +/-
0.03, we estimate that n_bar/n = 0.64 +/- 0.04.Comment: 326 authors, 6 pages text, 5 figures, 1 Table. Submitted to PRL.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Mid-Rapidity Direct-Photon Production in p+p Collisions at sqrt(s) = 200 GeV
A measurement of direct photons in p+p collisions at sqrt(s)=200 GeV is
presented. A photon excess above background from pi^0 --> gamma+gamma, eta -->
gamma+gamma, and other decays is observed in the transverse momentum range 5.5
< p_T < 7 GeV/c. The result is compared to a next-to-leading-order perturbative
QCD calculation. Within errors, good agreement is found between the QCD
calculation and the measured result.Comment: 330 authors, 7 pages text, RevTeX, 2 figures, 2 tables. Submitted to
Physical Review D. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
Scaling properties of proton and anti-proton production in sqrt(s_NN) = 200 GeV Au + Au collisions
We report on the yield of protons and anti-protons, as a function of
centrality and transverse momentum, in Au+Au collisions at sqrt(s_NN) = 200 GeV
measured at mid-rapidity by the PHENIX experiment at RHIC. In central
collisions at intermediate transverse momenta (1.5 < p_T < 4.5 GeV/c) a
significant fraction of all produced particles are protons and anti-protons.
They show a centrality-scaling behavior different from that of pions. The
p-bar/pion and p/pion ratios are enhanced compared to peripheral Au+Au, p+p,
and electron+positron collisions. This enhancement is limited to p_T < 5 GeV/c
as deduced from the ratio of charged hadrons to pi^0 measured in the range 1.5
< p_T < 9 GeV/c.Comment: 325 authors, 6 pages text, 4 figures, RevTeX 4. Minor changes to text
and figures to meet PRL length restrictions; no changes to figures;
resubmitted to PRL. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
Suppressed pi^0 Production at Large Transverse Momentum in Central Au+Au Collisions at sqrt(s_NN) = 200 GeV
Transverse momentum spectra of neutral pions in the range 1 < p_T < 10 GeV/c
have been measured at mid-rapidity by the PHENIX experiment at RHIC in Au+Au
collisions at sqrt(s_NN) = 200 GeV. The pi^0 multiplicity in central reactions
is significantly below the yields measured at the same sqrt(s_NN) in peripheral
Au+Au and p+p reactions scaled by the number of nucleon-nucleon collisions. For
the most central bin, the suppression factor is ~2.5 at p_T = 2 GeV/c and
increases to ~4-5 at p_T ~= 4 GeV/c. At larger p_T, the suppression remains
constant within errors. The deficit is already apparent in semi-peripheral
reactions and increases smoothly with centrality.Comment: 326 authors, 6 pages text, RevTeX, 3 figures, 2 tables. Submitted to
PRL. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
J/Psi Production in Au-Au Collisions at sqrt(s_NN) = 200 GeV at the Relativistic Heavy Ion Collider
First results on charm quarkonia production in heavy ion collisions at the
Relativistic Heavy Ion Collider (RHIC) are presented. The yield of J/Psi's
measured in the PHENIX experiment via electron-positron decay pairs at
mid-rapidity for Au-Au reactions at sqrt(s_NN) = 200 GeV are analyzed as a
function of collision centrality. For this analysis we have studied 49.3
million minimum bias Au-Au reactions. We present the J/Psi invariant yield
dN/dy for peripheral and mid-central reactions. For the most central collisions
where we observe no signal above background, we quote 90% confidence level
upper limits. We compare these results with our J/Psi measurement from
proton-proton reactions at the same energy. We find that our measurements are
not consistent with models that predict strong enhancement relative to binary
collision scaling.Comment: 325 authors, 11 pages text, 6 figures, 4 tables, RevTeX 4. Accepted
for publication as a regular article in Physical Review C. This version has
minor changes to respond to referee suggestions. Plain text data tables for
the points plotted in figures for this and previous PHENIX publications are
publicly available at http://www.phenix.bnl.gov/papers.htm
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