Constrained structure of ancient Chinese poetry facilitates speech content grouping

Ancient Chinese poetry is constituted by structured language that deviates from ordinary language usage [1, 2]; its poetic genres impose unique combinatory constraints on linguistic elements [3]. How does the constrained poetic structure facilitate speech segmentation when common linguistic [4, 5, 6, 7, 8] and statistical cues [5, 9] are unreliable to listeners in poems? We generated artificial Jueju, which arguably has the most constrained structure in ancient Chinese poetry, and presented each poem twice as an isochronous sequence of syllables to native Mandarin speakers while conducting magnetoencephalography (MEG) recording. We found that listeners deployed their prior knowledge of Jueju to build the line structure and to establish the conceptual flow of Jueju. Unprecedentedly, we found a phase precession phenomenon indicating predictive processes of speech segmentation—the neural phase advanced faster after listeners acquired knowledge of incoming speech. The statistical co-occurrence of monosyllabic words in Jueju negatively correlated with speech segmentation, which provides an alternative perspective on how statistical cues facilitate speech segmentation. Our findings suggest that constrained poetic structures serve as a temporal map for listeners to group speech contents and to predict incoming speech signals. Listeners can parse speech streams by using not only grammatical and statistical cues but also their prior knowledge of the form of language

Covalent-bonded graphyne polymers with high hardness

Eight covalent-bonded graphyne polymers have been proposed using the newly developed USPEX and CALYPSO methods based on the first principle calculations. These polymers are energetically more favorable than the corresponding graphyne under ambient pressure, and seven of them are more stable than fullerene C₆₀, indicating their existence possibilities. The mechanical and dynamic stabilities of these crystal structures have been confirmed by calculating their elastic constants and phonon dispersion curves, respectively. The newly developed variable-cell nudged elastic band (VC-NEV) simulations show that the graphyne → polymer transformation exhibits lower energy barrier than the graphite → diamond transformation. Two of the graphyne polymers have been found to be superhard, and the others are hard materials. These graphyne polymers possess tunable electronic properties from metallic to semiconductive.Запропоновано вісім ковалентно-зв’язаних полімерів графана, отриманих за допомогою нещодавно розроблених методів USPEX і CALYPSO, заснованих на розрахунках з перших принципів. Ці полімери енергетично більш вигідні, ніж відповідні графани під атмосферним тиском, і сім з них є більш стабільними, ніж фулерен C₆₀, що вказує на можливість їх існування. Механічна і динамічна стабільність таких кристалічних структур підтверджуються розрахунком їх пружних констант і кривими дисперсії фононів відповідно. Нещодавно здійснене моделювання змінної комірки збудженої пружною зони показало, що перетворення графан → полімер відбувається при більш низькому енергетичному бар’єрі, ніж перетворення графіт → алмаз. Встановлено, що два полімера графана є надтвердими, а інші – твердими матеріалами. Ці полімери графана мають електронні властивості, що змінюються від металічних до напівпровідникових.Предложены восемь ковалентно-связанных полимеров графана, полученных с помощью недавно разработанных методов USPEX и CALYPSO, основанных на расчетах из первых принципов. Эти полимеры энергетически более выгодны, чем соответствующие графаны при атмосферном давлении, и семь из них являются более стабильными, чем фуллерен C₆₀, что указывает на возможность их существования. Механическая и динамическая стабильность таких кристаллических структур подтверждаются расчетом их упругих констант и кривыми дисперсии фононов соответственно. Недавно осуществленное моделирование переменной ячейки возбужденной упругой зоны показало, что превращение графан → полимер происходит при более низком энергетическом барьере, чем превращение графит → алмаз. Установлено, что два полимера графана являются сверхтвердыми, а другие – твердыми материалами. Эти полимеры графана имеют электронные свойства, изменяющиеся от металлических до полупроводниковых

Isospin effect in the statistical sequential decay

Isospin effect of the statistical emission fragments from the equilibrated source is investigated in the frame of statistical binary decay implemented into GEMINI code, isoscaling behavior is observed and the dependences of isoscaling parameters $\alpha$ and $\beta$ on emission fragment size, source size, source isospin asymmetry and excitation energies are studied. Results show that $\alpha$ and $\beta$ neither depends on light fragment size nor on source size. A good linear dependence of $\alpha$ and $\beta$ on the inverse of temperature $T$ is manifested and the relationship of $\alpha=4C_{sym}[(Z_{s}/A_{s})_{1}^{2}-(Z_{s}/A_{s})_{2}^{2}]/T$ and $\beta=4C_{sym}[(N_{s}/A_{s})_{1}^{2}-(N_{s}/A_{s})_{2}^{2}]/T$ from different isospin asymmetry sources are satisfied. The symmetry energy coefficient $C_{sym}$ extracted from simulation results is $\sim$ 23 MeV which includes both the volume and surface term contributions, of which the surface effect seems to play a significant role in the symmetry energy.Comment: 8 pages, 8 figures; A new substantially modified version which has been accepted by the Physical Review

Critical Current Density and Resistivity of MgB2 Films

The high resistivity of many bulk and film samples of MgB2 is most readily explained by the suggestion that only a fraction of the cross-sectional area of the samples is effectively carrying current. Hence the supercurrent (Jc) in such samples will be limited by the same area factor, arising for example from porosity or from insulating oxides present at the grain boundaries. We suggest that a correlation should exist, Jc ~ 1/{Rho(300K) - Rho(50K)}, where Rho(300K) - Rho(50K) is the change in the apparent resistivity from 300 K to 50 K. We report measurements of Rho(T) and Jc for a number of films made by hybrid physical-chemical vapor deposition which demonstrate this correlation, although the "reduced effective area" argument alone is not sufficient. We suggest that this argument can also apply to many polycrystalline bulk and wire samples of MgB2.Comment: 11 pages, 3 figure