35,385 research outputs found
No association of CTLA-4 polymorphisms with susceptibility to Behcet disease
Background: Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a key negative regulator of T lymphocytes and has been shown to be associated with a number of autoimmune diseases. The present study was performed to assess the association between CTLA-4 polymorphisms and Behcet disease (BD) in Chinese patients. Methods: Two hundred and twenty-eight BD patients and 207 controls were analysed for four single nucleotide polymorphisms (SNPs) (21661A/G, 2318C/T, + 49G/A and CT60G/A) in the CTLA-4 gene by PCR-restriction fragment length polymorphism (RFLP) analysis. The association between SNP +49A/G and BD in Chinese population as well as other ethnic groups was analysed by meta-analysis. Results: No association could be detected between CTLA-4 SNPs or haplotypes and BD. Also, no association was observed between CTLA-4 polymorphisms and BD subgroups, stratified by clinical features. A meta-analysis showed that there was no heterogeneity between studies (p = 0.60, I-2 = 0%) and that CTLA-4 SNP + 49 was not associated with BD (overall effect: Z = 0.26, p = 0.79). Conclusion: This study and a meta-analysis failed to demonstrate any association between the tested CTLA-4 polymorphisms and B
Eruption of a multi-flux-rope system in solar active region 12673 leading to the two largest flares in Solar Cycle 24
Solar active region (AR) 12673 in 2017 September produced two largest flares
in Solar Cycle 24: the X9.3 flare on September 06 and the X8.2 flare on
September 10. We attempt to investigate the evolutions of the two great flares
and their associated complex magnetic system in detail. Aided by the NLFFF
modeling, we identify a double-decker flux rope configuration above the
polarity inversion line (PIL) in the AR core region. The north ends of these
two flux ropes were rooted in a negative- polarity magnetic patch, which began
to move along the PIL and rotate anticlockwise before the X9.3 flare on
September 06. The strong shearing motion and rotation contributed to the
destabilization of the two magnetic flux ropes, of which the upper one
subsequently erupted upward due to the kink-instability. Then another two sets
of twisted loop bundles beside these ropes were disturbed and successively
erupted within 5 minutes like a chain reaction. Similarly, multiple ejecta
components were detected to consecutively erupt during the X8.2 flare occurring
in the same AR on September 10. We examine the evolution of the AR magnetic
fields from September 03 to 06 and find that five dipoles emerged successively
at the east of the main sunspot. The interactions between these dipoles took
place continuously, accompanied by magnetic flux cancellations and strong
shearing motions. In AR 12673, significant flux emergence and successive
interactions between the different emerging dipoles resulted in a complex
magnetic system, accompanied by the formations of multiple flux ropes and
twisted loop bundles. We propose that the eruptions of a multi-flux-rope system
resulted in the two largest flares in Solar Cycle 24.Comment: 10 pages, 8 figures. To be published in A&
Chemoviscosity modeling for thermosetting resins
A chemoviscosity model, which describes viscosity rise profiles accurately under various cure cycles, and correlates viscosity data to the changes of physical properties associated with structural transformations of the thermosetting resin system during cure, was established. Work completed on chemoviscosity modeling for thermosetting resins is reported
Studies on chemoviscosity modeling for thermosetting resins
A new analytical model for simulating chemoviscosity of thermosetting resins has been formulated. The model is developed by modifying the well-established Williams-Landel-Ferry (WLF) theory in polymer rheology for thermoplastic materials. By introducing a relationship between the glass transition temperature Tg(t) and the degree of cure alpha(t) of the resin system under cure, the WLF theory can be modified to account for the factor of reaction time. Temperature dependent functions of the modified WLF theory constants C sub 1 (t) and C sub 2 (t) were determined from the isothermal cure data. Theoretical predictions of the model for the resin under dynamic heating cure cycles were shown to compare favorably with the experimental data. This work represents progress toward establishing a chemoviscosity model which is capable of not only describing viscosity profiles accurately under various cure cycles, but also correlating viscosity data to the changes of physical properties associated with the structural transformation of the thermosetting resin systems during cure
Detection of Minimum-Ionizing Particles and Nuclear Counter Effect with Pure BGO and BSO Crystals with Photodiode Read-out
Long BGO (Bismuth Germanate) and BSO (Bismuth Silicate) crystals coupled with
silicon photodiodes have been used to detect minimum-ionizing particles(MIP).
With a low noise amplifier customized for this purpose, the crystals can detect
MIPs with an excellent signal-to-noise ratio. The NCE(Nuclear Counter Effect}
is also clearly observed and measured. Effect of full and partial wrapping of a
reflector around the crystal on light collection is also studied.Comment: 18 pages, including 5 figures; LaTeX and EP
An alternative non-Markovianity measure by divisibility of dynamical map
Identifying non-Markovianity with non-divisibility, we propose a measure for
non-Markovinity of quantum process. Three examples are presented to illustrate
the non-Markovianity, measure for non-Markovianity is calculated and discussed.
Comparison with other measures of non-Markovianity is made. Our
non-Markovianity measure has the merit that no optimization procedure is
required and it is finite for any quantum process, which greatly enhances the
practical relevance of the proposed measure.Comment: 6 pages, 3 figue
On Singularity Formation of a Nonlinear Nonlocal System
We investigate the singularity formation of a nonlinear nonlocal system. This
nonlocal system is a simplified one-dimensional system of the 3D model that was
recently proposed by Hou and Lei in [13] for axisymmetric 3D incompressible
Navier-Stokes equations with swirl. The main difference between the 3D model of
Hou and Lei and the reformulated 3D Navier-Stokes equations is that the
convection term is neglected in the 3D model. In the nonlocal system we
consider in this paper, we replace the Riesz operator in the 3D model by the
Hilbert transform. One of the main results of this paper is that we prove
rigorously the finite time singularity formation of the nonlocal system for a
large class of smooth initial data with finite energy. We also prove the global
regularity for a class of smooth initial data. Numerical results will be
presented to demonstrate the asymptotically self-similar blow-up of the
solution. The blowup rate of the self-similar singularity of the nonlocal
system is similar to that of the 3D model.Comment: 28 pages, 9 figure
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