5,923 research outputs found

    Deep and cortical gray matter volumetric of extremely low gestational age and full term newborn children at 9 to 11 years of age

    Full text link
    PURPOSE: Extremely low gestation age newborns (ELGANs) are at high risk for developmental brain abnormalities. This study is to determine deep and superficial gray matter volumetric abnormalities of ELGAN children and full term children at 9 to 11 years of age. METHODS: High-resolution magnetic resonance imaging (MRI) scans were obtained from 160 ELGAN children (70 males and 90 females) and 30 full term children (15 males and 15 females) using a dual-echo turbo spin-echo (DE-TSE) pulse sequence at 3.0T (or 1.5T at only one site). The DICOM MR images were processed with quantitative MRI algorithms programmed in Mathcad. The brain deep gray matter (dGM) was manually segmented; dGM and cortical gray matter (cGM) volumes were quantified using semi-automated clustering segmentation algorithms. RESULTS: ELGAN children had smaller deep gray matter volume (41.86 ± 7.42 ml) than full term children (49.24 ± 10.91 ml). Deep gray matter volumes of ELGAN children showed similar distribution range (SD = 7.42 ml) with the full term children (SD = 10.91 ml). About 83% of the ELGAN children had smaller deep gray matter volumes compared to the average volume of full term children at the same ages. Male children had smaller deep gray matter volumes in ELGAN (42.77 ± 7.09 ml) than in full term (51.74 ± 9.76 ml), but female children had similar deep gray matter volumes in ELGAN (41.14 ± 7.62 ml) with full term (44.27 ± 7.56 ml). Additionally, smaller deep gray matter volumes were observed more often in males (90%) than in females (65%). Cortical gray matter volumes of ELGAN children distributed from 345.60 to 1177.50ml. Moreover, female ELGAN children had smaller cortical gray matter volumes (828.14 ± 147.61 ml) than males (883.13 ± 151.34 ml). Correlation analysis revealed a positive correlation between cerebral deep gray matter volumes and total gray matter volumes (total: r = 0.57, p<0.0001; male: r = 0.542, p < 0.0001; female: r = 0.587, p < 0.0001). CONCLUSION: Male ELGAN children had smaller brain deep gray matter volumes than full term children at ages of 9 to 11 years, but not females. Cortical gray matter volumes of female ELGAN were smaller than male ELGAN. Smaller deep gray matter volumes were associated with smaller total gray matter volumes in ELGAN children

    Complexity growth rates for AdS black holes in massive gravity and f(R)f(R) gravity

    Full text link
    The "complexity = action" duality states that the quantum complexity is equal to the action of the stationary AdS black holes within the Wheeler-DeWitt patch at late time approximation. We compute the action growth rates of the neutral and charged black holes in massive gravity and the neutral, charged and Kerr-Newman black holes in f(R)f(R) gravity to test this conjecture. Besides, we investigate the effects of the massive graviton terms, higher derivative terms and the topology of the black hole horizon on the complexity growth rate.Comment: 11 pages, no figur

    Influence of vector interactions on the hadron-quark/gluon phase transition

    Full text link
    The hadron-quark/gluon phase transition is studied in the two-phase model. As a further study of our previous work, both the isoscalar and isovector vector interactions are included in the Polyakov loop modified Nambu--Jona-Lasinio model (PNJL) for the quark phase. The relevance of the exchange (Fock) terms is stressed and suitably accounted for. The calculation shows that the isovector vector interaction delays the phase transition to higher densities and the range of the mixed phase correspondingly shrinks. Meanwhile the asymmetry parameter of quark matter in the mixed phase decreases with the strengthening of this interaction channel. This leads to some possible observation signals being weakened, although still present. We show that these can be rather general effects of a repulsion in the quark phase due to the symmetry energy. This is also confirmed by a simpler calculation with the MIT--Bag model. However, the asymmetry parameter of quark matter is slightly enhanced with the inclusion of the isoscalar vector interaction, but the phase transition will be moved to higher densities. The largest uncertainty on the phase transition lies in the undetermined coupling constants of the vector interactions. In this respect new data on the mixed phase obtained from Heavy Ion Collisions at Intermediate Energies appear very important.Comment: submitted to Phys. Rev.

    Optical Monitoring of the Seyfert Galaxy NGC 4151 and Possible Periodicities in the Historical Light Curve

    Full text link
    We report B, V, and R band CCD photometry of the Seyfert galaxy NGC 4151 obtained with the 1.0-m telescope at Weihai Observatory of Shandong University and the 1.56-m telescope at Shanghai Astronomical Observatory from 2005 December to 2013 February. Combining all available data from literature, we have constructed a historical light curve from 1910 to 2013 to study the periodicity of the source using three different methods (the Jurkevich method, the Lomb-Scargle periodogram method and the Discrete Correlation Function method). We find possible periods of P_1=4\pm0.1, P_2=7.5\pm0.3 and P_3=15.9\pm0.3 yr.Comment: 8 pages, 5 figures, Accepted by Research in Astronomy and Astrophysic
    corecore