624 research outputs found
Thermal conductivity of deformed carbon nanotubes
We investigate the thermal conductivity of four types of deformed carbon
nanotubes by using the nonequilibrium molecular dynamics method. It is reported
that various deformations have different influence on the thermal properties of
carbon nanotubes. For the bending carbon nanotubes, the thermal conductivity is
independent on the bending angle. However, the thermal conductivity increases
lightly with XY-distortion and decreases rapidly with Z-distortion. The thermal
conductivity does not change with the screw ratio before the breaking of carbon
nanotubes but decreases sharply after the critical screw ratio.Comment: 6figure
Association of p53 rs1042522, MDM2 rs2279744, and p21 rs1801270 polymorphisms with retinoblastoma risk and invasion in a Chinese population.
Single nucleotide polymorphisms (SNPs) of p53 rs1042522, MDM2 rs2279744 and p21 rs1801270, all in the p53 pathway, which plays a crucial role in DNA damage and genomic instability, were reported to be associated with cancer risk and pathologic characteristics. This case-control study was designed to analyse the association between these SNPs and retinoblastoma (RB) in a Chinese Han population. These SNPs in 168 RB patients and 185 adult controls were genotyped using genomic DNA from venous blood. No significant difference was observed in allele or genotypic frequencies of these SNPs between Chinese RB patients and controls (all P > 0.05). However, the rs1042522 GC genotype showed a protective effect against RB invasion, as demonstrated by event-free survival (HR = 0.53, P = 0.007 for GC versus GG/CC). This effect was significant for patients with a lag time >1 month and no pre-enucleation treatment (P = 0.007 and P = 0.010, respectively), indicating an interaction between p53 rs1042522 and clinical characteristics, including lag time and pre-enucleation treatment status. Thus, the rs1042522 SNP may be associated with RB invasion in the Han Chinese population; however, further large and functional studies are needed to assess the validity of this association
A negative feedback loop mediated by the Bcl6-cullin 3 complex limits Tfh cell differentiation
Induction of Bcl6 (B cell lymphoma 6) is essential for T follicular helper (Tfh) cell differentiation of antigen-stimulated CD4(+) T cells. Intriguingly, we found that Bcl6 was also highly and transiently expressed during the CD4(+)CD8(+) (double positive [DP]) stage of T cell development, in association with the E3 ligase cullin 3 (Cul3), a novel binding partner of Bcl6 which ubiquitinates histone proteins. DP stage-specific deletion of the E3 ligase Cul3, or of Bcl6, induced the derepression of the Bcl6 target genes Batf (basic leucine zipper transcription factor, ATF-like) and Bcl6, in part through epigenetic modifications of CD4(+) single-positive thymocytes. Although they maintained an apparently normal phenotype after emigration, they expressed increased amounts of Batf and Bcl6 at basal state and produced explosive and prolonged Tfh responses upon subsequent antigen encounter. Ablation of Cul3 in mature CD4(+) splenocytes also resulted in dramatically exaggerated Tfh responses. Thus, although previous studies have emphasized the essential role of Bcl6 in inducing Tfh responses, our findings reveal that Bcl6-Cul3 complexes also provide essential negative feedback regulation during both thymocyte development and T cell activation to restrain excessive Tfh responses
The LAMOST Survey of Background Quasars in the Vicinity of the Andromeda and Triangulum Galaxies -- II. Results from the Commissioning Observations and the Pilot Surveys
We present new quasars discovered in the vicinity of the Andromeda and
Triangulum galaxies with the LAMOST during the 2010 and 2011 observational
seasons. Quasar candidates are selected based on the available SDSS, KPNO 4 m
telescope, XSTPS optical, and WISE near infrared photometric data. We present
509 new quasars discovered in a stripe of ~135 sq. deg from M31 to M33 along
the Giant Stellar Stream in the 2011 pilot survey datasets, and also 17 new
quasars discovered in an area of ~100 sq. deg that covers the central region
and the southeastern halo of M31 in the 2010 commissioning datasets. These 526
new quasars have i magnitudes ranging from 15.5 to 20.0, redshifts from 0.1 to
3.2. They represent a significant increase of the number of identified quasars
in the vicinity of M31 and M33. There are now 26, 62 and 139 known quasars in
this region of the sky with i magnitudes brighter than 17.0, 17.5 and 18.0
respectively, of which 5, 20 and 75 are newly-discovered. These bright quasars
provide an invaluable collection with which to probe the kinematics and
chemistry of the ISM/IGM in the Local Group of galaxies. A total of 93 quasars
are now known with locations within 2.5 deg of M31, of which 73 are newly
discovered. Tens of quasars are now known to be located behind the Giant
Stellar Stream, and hundreds behind the extended halo and its associated
substructures of M31. The much enlarged sample of known quasars in the vicinity
of M31 and M33 can potentially be utilized to construct a perfect astrometric
reference frame to measure the minute PMs of M31 and M33, along with the PMs of
substructures associated with the Local Group of galaxies. Those PMs are some
of the most fundamental properties of the Local Group.Comment: 26 pages, 6 figures, AJ accepte
Orbital Origin of Extremely Anisotropic Superconducting Gap in Nematic Phase of FeSe Superconductor
The iron-based superconductors are characterized by multiple-orbital physics
where all the five Fe 3 orbitals get involved. The multiple-orbital nature
gives rise to various novel phenomena like orbital-selective Mott transition,
nematicity and orbital fluctuation that provide a new route for realizing
superconductivity. The complexity of multiple-orbital also asks to disentangle
the relationship between orbital, spin and nematicity, and to identify dominant
orbital ingredients that dictate superconductivity. The bulk FeSe
superconductor provides an ideal platform to address these issues because of
its simple crystal structure and unique coexistence of superconductivity and
nematicity. However, the orbital nature of the low energy electronic
excitations and its relation to the superconducting gap remain controversial.
Here we report direct observation of highly anisotropic Fermi surface and
extremely anisotropic superconducting gap in the nematic state of FeSe
superconductor by high resolution laser-based angle-resolved photoemission
measurements. We find that the low energy excitations of the entire hole pocket
at the Brillouin zone center are dominated by the single orbital. The
superconducting gap exhibits an anti-correlation relation with the
spectral weight near the Fermi level, i.e., the gap size minimum (maximum)
corresponds to the maximum (minimum) of the spectral weight along the
Fermi surface. These observations provide new insights in understanding the
orbital origin of the extremely anisotropic superconducting gap in FeSe
superconductor and the relation between nematicity and superconductivity in the
iron-based superconductors.Comment: 19 pages, 4 figure
Promising treatment outcomes of intensity-modulated radiation therapy for nasopharyngeal carcinoma patients with N0 disease according to the seventh edition of the AJCC staging system
Measurement of azimuthal asymmetries in inclusive charged dipion production in annihilations at = 3.65 GeV
We present a measurement of the azimuthal asymmetries of two charged pions in
the inclusive process based on a data set of 62
at the center-of-mass energy GeV collected with
the BESIII detector. These asymmetries can be attributed to the Collins
fragmentation function. We observe a nonzero asymmetry, which increases with
increasing pion momentum. As our energy scale is close to that of the existing
semi-inclusive deep inelastic scattering experimental data, the measured
asymmetries are important inputs for the global analysis of extracting the
quark transversity distribution inside the nucleon and are valuable to explore
the energy evolution of the spin-dependent fragmentation function.Comment: 7 pages, 5 figure
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