155 research outputs found
Time-domain response of nabla discrete fractional order systems
This paper investigates the time--domain response of nabla discrete
fractional order systems by exploring several useful properties of the nabla
discrete Laplace transform and the discrete Mittag--Leffler function. In
particular, we establish two fundamental properties of a nabla discrete
fractional order system with nonzero initial instant: i) the existence and
uniqueness of the system time--domain response; and ii) the dynamic behavior of
the zero input response. Finally, one numerical example is provided to show the
validity of the theoretical results.Comment: 13 pages, 6 figure
A stochastic mirror-descent algorithm for solving over an multi-agent system
summary:In this paper, we consider a distributed stochastic computation of with local set constraints over an multi-agent system, where each agent over the network only knows a few rows or columns of matrixes. Through formulating an equivalent distributed optimization problem for seeking least-squares solutions of , we propose a distributed stochastic mirror-descent algorithm for solving the equivalent distributed problem. Then, we provide the sublinear convergence of the proposed algorithm. Moreover, a numerical example is also given to illustrate the effectiveness of the proposed algorithm
A cell-free system toward deciphering the post-translational modification barcodes of Oct4 in different cellular contexts
AbstractThe octamer-binding transcription factor 4 (Oct4) is essential for maintaining the self-renewal and pluripotency of embryonic stem cells (ESCs). Post-translational modifications (PTMs) of Oct4 critically control its structure, function and intracellular localization. However, determination of Oct4 PTM profiles has largely been restricted by the quantity and purity of the Oct4 protein samples required for mass spectrometric analyses. In this study, by incubating the Escherichia coli-derived His-tagged Oct4 proteins with the whole cell lysates of a variety of human cells followed by retrieving the reacted Oct4 proteins with the Ni–NTA beads, we developed a labor- and cost-effective in vitro PTM method that allowed for mass spectrometric determination of the phosphorylation profiles of Oct4 proteins exposed to various cell-free systems. A number of Oct4 phosphorylation sites that were commonly present in all the cell-free systems or specifically present in a particular cellular context were identified, indicating that Oct4 is controlled by both common and distinct PTM regulatory pathways. Our work provided a proof-of-concept that such a cell-free system-based in vitro PTM approach can be applied to systematically map out the physiologically-relevant PTM sites in Oct4 proteins, which opened up an avenue to fully decipher the Oct4 PTM barcodes in various cellular contexts
Magnon-magnon interaction in monolayer MnBiTe
MnBiTe, the first confirmed intrinsic antiferromagnetic topological
insulator, have attracted more and more attention in recent years. Here we
investigate the energy correction and lifetime of magnons in MnBiTe
caused by magnon-magnon interaction. Firstly, a first-principles calculation
was performed to get the parameters of the magnetic Hamiltonian of
MnBiTe. Then the perturbation method of many-body Green's function is
applied and the 1st-order self-energy [] and 2nd-order
self-energy [] of magnon are
obtained. Numerical computation shows that the correction from both
and are
strongly dependent on momentum and temperature, the energy renormalization near
Brillouin zone (BZ) boundary is obviously stronger than that near BZ centre. We
also find that some dip structures occur in renormalized magnon spectrum near
and points, and these dip structures should be attributed to
.Comment: 7 pages, 7 figure
Magnetic interactions and possible structural distortion in kagome FeGe from first-principles study and symmetry analysis
Based on density functional theory and symmetry analysis, we present a
comprehensive investigation of electronic structure, magnetic properties and
possible structural distortion of magnetic kagome metal FeGe. We estimate the
magnetic parameters including Heisenberg and Dzyaloshinskii-Moriya (DM)
interactions, and find that the ferromagnetic nearest-neighbor
dominates over the others, while the magnetic interactions between nearest
kagome layers favors antiferromagnetic. The N\'{e}el temperature and
Curie-Weiss temperature are successfully reproduced, and the
calculated magnetic anisotropy energy is also in consistent with the
experiment. However, these reasonable Heisenberg interactions and magnetic
anisotropy cannot explain the double cone magnetic transition, and the DM
interactions, which even exist in the centrosymmetric materials, can result in
this small magnetic cone angle. Unfortunately, due to the crystal symmetry of
the high-temperature structure, the net contribution of DM interactions to
double cone magnetic structure is absent. Based on the experimental supercell, we thus explore the subgroups of the parent phase. Group
theoretical analysis reveals that there are 68 different distortions, and only
four of them (space group or ) without inversion and mirror
symmetry thus can explain the low-temperature magnetic structure. Furthermore,
we suggest that these four proposed CDW phases can be identified by using Raman
spectroscopy. Since DM interactions are very sensitive to small atomic
displacements and symmetry restrictions, we believe that symmetry analysis is
an effective method to reveal the interplay of delicate structural distortions
and complex magnetic configurations
Impact of HBeAg on the maturation and function of dendritic cells
AbstractObjectivesHBV infection typically leads to chronic hepatitis in newborns and some adults with weakened immune systems. The mechanisms by which virus escapes immunity remain undefined. Regulatory dendritic cells (DCregs) contributing to immune escape have been described. We wondered whether or not HBeAg as an immunomodulatory protein could induce DCreg which might subsequently result into HBV persistence.MethodsThe immunophenotyping, T-cell activation and cytokine production were analyzed in HBeAg-treated DCs from normal or cyclophosphamide (Cy)-induced immunocompromised mice.ResultsHBeAg tended to promote bone marrow derived DCs (BMDCs) from Cy-treated mice into CD11bhighPIR-B+ regulatory DCs exhibiting the lowest T-cell stimulatory capacity and interleukin (IL)-12p70 production compared with controls. Neutralization of IL-10 significantly inhibited the regulatory effect of these DCs on T-cell stimulation of mature DCs. After lipopolysaccharides (LPS) stimulation, marked phosphorylation of Akt was detected in HBeAg treated DCs from immunocompromised mice. Blocking the PI3K-Akt pathway by LY294002 led to an enhancement of IL-12 production. PI3K signalling pathway appears to be involved in the decreased IL-12 secretion by HBeAg treated DCs.ConclusionsThese findings suggest that HBeAg may program the generation of a new DC subset with regulatory capacity under the condition of immunosuppression, which may presumably contribute to the persistent HBV infection
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