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

A joint investigation of facilitation and interference effects of semantic and phonological similarityin a continuous naming task

Semantic and phonological similarity effects provide critical constraints on the mechanisms underlying language production. In the present study, we jointly investigated effects of semantic and phonological similarity using the continuous naming task. In the semantic condition, Chinese Mandarin speakers named a list of pictures composed of 12 semantic category sets with 5 items from each semantic category, while in the phonological condition, they named a list of pictures from 12 phonological sets of 5 items sharing a spoken syllable. Related pictures occurred on adjacent trials, or were separated by 2, 4, or 6 unrelated pictures. Similar results were found across the semantic and phonological conditions: naming was facilitated by the directly preceding production of a related picture. For nonconsecutive related responses, naming latency increased linearly as a function of the number of preceding production instances of related pictures. Parallel patterns of facilitation and interference effects arising from semantic and phonological similarity suggest universal principles which govern language production

Distribution of Spectral Lags in Gamma Ray Bursts

Using the data acquired in the Time To Spill (TTS) mode for long gamma-ray bursts (GRBs) collected by the Burst and Transient Source Experiment on board the Compton Gamma Ray Observatory (BATSE/CGRO), we have carefully measured spectral lags in time between the low (25-55 keV) and high (110-320 keV) energy bands of individual pulses contained in 64 multi-peak GRBs. We find that the temporal lead by higher-energy gamma-ray photons (i.e., positive lags) is the norm in this selected sample set of long GRBs. While relatively few in number, some pulses of several long GRBs do show negative lags. This distribution of spectral lags in long GRBs is in contrast to that in short GRBs. This apparent difference poses challenges and constraints on the physical mechanism(s) of producing long and short GRBs. The relation between the pulse peak count rates and the spectral lags is also examined. Observationally, there seems to be no clear evidence for systematic spectral lag-luminosity connection for pulses within a given long GRB.Comment: 20 pages, 4 figure

Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide

We report that Bi$_2$Se$_3$ thin films can be epitaxially grown on SrTiO$_{3}$ substrates, which allow for very large tunablity in carrier density with a back-gate. The observed low field magnetoconductivity due to weak anti-localization (WAL) has a very weak gate-voltage dependence unless the electron density is reduced to very low values. Such a transition in WAL is correlated with unusual changes in longitudinal and Hall resistivities. Our results suggest much suppressed bulk conductivity at large negative gate-voltages and a possible role of surface states in the WAL phenomena. This work may pave a way for realizing three-dimensional topological insulators at ambient conditions.Comment: 5 pages, 4 figures

The Single-degenerate Binary Origin of Tycho's Supernova as Traced by the Stripped Envelope of the Companion

We propose that a non-thermal X-ray arc inside the remnant of Tycho's supernova (SN) represents the interaction between the SN ejecta and the companion star's envelope lost in the impact of the explosion. The X-ray emission of the remnant further shows an apparent shadow casted by the arc in the opposite direction of the explosion site, consistent with the blocking of the SN ejecta by the envelope. This scenario supports the single degenerate binary origin of Tycho's SN. The properties of the X-ray arc, together with the previous detection of the companion candidate and its space velocity by Ruiz-Lapuente et al. (2004) and Hern\'{a}ndez et al.(2009), enables us to further infer 1) the progenitor binary has a period of 4.9$^{+5.3}_{-3.0}$ days, 2) the companion gained a kick velocity of 42$\pm$30 km s$^{-1}$, and 3) the stripped envelope mass is about 0.0016($\leq0.0083$) M_{\sun}. However, we notice that the nature of the companion candidate is still under debate, and the above parameters need to be revised according to the actual properties of the companion candidate. Further work to measure the proper motion of the arc and to check the capability of the interaction to emit the amount of X-rays observed from the arc is also needed to validate the current scenario.Comment: 17 pages with 4 figures included, accepted to Ap

GABA operates upstream of H+-ATPase and improves salinity tolerance in Arabidopsis by enabling cytosolic K+ retention and Na+ exclusion

The non-protein amino acid γ-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to salinity. However, the physiological rationale for this elevation remains elusive. This study compared electrophysiological and whole-plant responses of salt-treated Arabidopsis mutants pop2-5 and gad1,2, which have different abilities to accumulate GABA. The pop2-5 mutant, which was able to overaccumulate GABA in its roots, showed a salt-tolerant phenotype. On the contrary, the gad1,2 mutant, lacking the ability to convert glutamate to GABA, showed oversensitivity to salinity. The greater salinity tolerance of the pop2-5 line was explained by: (i) the role of GABA in stress-induced activation of H+-ATPase, thus leading to better membrane potential maintenance and reduced stress-induced K+ leak from roots; (ii) reduced rates of net Na+ uptake; (iii) higher expression of SOS1 and NHX1 genes in the leaves, which contributed to reducing Na+ concentration in the cytoplasm by excluding Na+ to apoplast and sequestering Na+ in the vacuoles; (iv) a lower rate of H2O2 production and reduced reactive oxygen species-inducible K+ efflux from root epidermis; and (v) better K+ retention in the shoot associated with the lower expression level of GORK channels in plant leaves