10,615 research outputs found
Production rates for hadrons, pentaquarks and , and di-baryon in relativistic heavy ion collisions by a quark combination model
The hadron production in relativistic heavy ion collisions is well described
by the quark combination model. The mixed ratios for various hadrons and the
transverse momentum spectra for long-life hadrons are predicted and agree with
recent RHIC data. The production rates for the pentaquarks , and the di-baryon are estimated, neglecting
the effect from the transition amplitude for constituent quarks to form an
exotic state.Comment: The difference between our model and other combination models is
clarified. The scaled transverse momentum spectra for pions, kaons and
protoms at both 130 AGeV and 200 AGeV are given, replacing the previous
results in transverse momentum spectr
X-ray Timing Observations of PSR J1930+1852 in the Crab-like SNR G54.1+0.3
We present new X-ray timing and spectral observations of PSR J1930+1852, the
young energetic pulsar at the center of the non-thermal supernova remnant
G54.1+0.3. Using data obtained with the Rossi X-ray Timing Explorer and Chandra
X-ray observatories we have derived an updated timing ephemeris of the 136 ms
pulsar spanning 6 years. During this interval, however, the period evolution
shows significant variability from the best fit constant spin-down rate of
s s, suggesting strong timing noise
and/or glitch activity. The X-ray emission is highly pulsed (
modulation) and is characterized by an asymmetric, broad profile (
duty cycle) which is nearly twice the radio width. The spectrum of the pulsed
emission is well fitted with an absorbed power law of photon index ; this is marginally harder than that of the unpulsed component. The
total 2-10 keV flux of the pulsar is erg cm
s. These results confirm PSR J1930+1852 as a typical Crab-like pulsar.Comment: 14 pages with 7 figures included, accepted to Ap
Parallel processing of semantics and phonology in spoken production:Evidence from blocked cyclic picture naming and EEG
Spoken language production involves lexical-semantic access and phonological encoding. A theoretically important question concerns the relative time course of these two cognitive processes. The predominant view has been that semantic and phonological codes are accessed in successive stages. However, recent evidence seems difficult to reconcile with a sequential view but rather suggests that both types of codes are accessed in parallel. Here, we used ERPs combined with the "blocked cyclic naming paradigm" in which items overlapped either semantically or phonologically. Behaviorally, both semantic and phonological overlap caused interference relative to unrelated baseline conditions. Crucially, ERP data demonstrated that the semantic and phonological effects emerged at a similar latency (similar to 180 msec after picture onset) and within a similar time window (180-380 msec). These findings suggest that access to phonological information takes place at a relatively early stage during spoken planning, largely in parallel with semantic processing
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