On a refinement of Wilf-equivalence for permutations

Recently, Dokos et al. conjectured that for all $k, m\geq 1$, the patterns $12\ldots k(k+m+1)\ldots (k+2)(k+1)$ and $(m+1)(m+2)\ldots (k+m+1)m\ldots 21$ are $maj$-Wilf-equivalent. In this paper, we confirm this conjecture for all $k\geq 1$ and $m=1$. In fact, we construct a descent set preserving bijection between $12\ldots k (k-1)$-avoiding permutations and $23\ldots k1$-avoiding permutations for all $k\geq 3$. As a corollary, our bijection enables us to settle a conjecture of Gowravaram and Jagadeesan concerning the Wilf-equivalence for permutations with given descent sets

Downregulation of protease activated receptor expression and cytokine production in P815 cells by RNA interference

Abstract Background Protease-activated receptors (PAR) are seven transmembrane G-coupled receptors comprising four genes (PAR-1 ~ PAR-4). Mast cell has been identified to be able to express PARs and release an array of cytokines upon activation. Recently, it was reported that interleukin (IL)-12 could regulate the expression of PARs in mast cells, and tryptase could induce IL-4 and IL-6 release from mast cells. In order to further investigate the issues, RNA interference (RNAi) technique was employed and small interfering RNAs (siRNA) of PARs were transfected in P815 cells. Results The results showed that siRNAs for PAR-1, PAR-2 and PAR-4 significantly downregulated expression of PAR-1, PAR-2 and PAR-4 mRNAs and proteins in P815 cells at 24, 48 and 72 h following transfection. siRNA PAR-1.2 and siRNA PAR-4.2 significantly reduced IL-12 induced upregulation of PAR-1 and PAR-4 expression, respectively when P815 cells were transfected with them for 48 h. siRNA PAR-2.3 blocked IL-12 induced downregulation of PAR-2 expression on both mRNA and protein levels. It was also observed that siRNA PAR-2.3 and siRNA PAR-1.2 reduced trypsin induced IL-4 release by approximately 92.6% and 65.3%, and SLIGKV-NH2 induced IL-4 release by 82.1% and 60.1%, respectively. Similarly, siRNA PAR-2.3 eliminated tryptase-induced IL-4 release by 75.3%, and siRNA PAR-1.2 diminished SFLLR-NH2 induced IL-4 release by 79.3%. However, siRNA PAR-1.2, siRNA PAR-2.3 and siRNA PAR-4.3 at 10 nM did not show any effect on tryptase-induced IL-6 release from P815 cells. Conclusion In conclusion, siRNAs of PARs can modulate PAR expression and PAR related cytokine production in mast cells, confirming that PARs are likely to play a role in allergic reactions.</p

Polarization properties of Raman scattering by surface phonon polaritons in GaAsP nanowires

Strong resonant enhancement of Raman scattering on photonic resonance was observed in GaAsP semiconductor nanowires. The enhancement allowed for detailed studies of the surface phonon polariton (SPhP) scattering peak on individual nanowires. In particular, for the first time, the effect of the nanowire cross section shape on SPhP properties has been investigated. It was found that the cross section flattening induces a strong polarisation and a spectral shift of SPhPs supported by such nanowire. The assisting numerical simulations allowed to link the induced polarisation effect to a splitting of the resonant HE11 mode in the flattened nanowire. The observed spectral shift of SPhP has been also theoretically reproduced in elliptical approximation for the flattened cross section. The obtained results pave a ground for engineering of SPhP polarisation response and accurate spectral control of SPhPs in applications utilising the nanowire morphology

Resonant enhancement of Raman scattering by surface phonon polaritons in GaAs nanowires

Surface optical phonons are normally considered as subtle and poorly reproducible features in the Raman spectra of nanostructured semiconductors, from which little or no information about the sample can be extracted. The present study demonstrates the potential for changing this situation. For a common type of GaAs semiconductor nanowire (NW), we have shown that due to a combination of size-resonant light concentration, tapered shape and favourable scattering geometry, the surface phonon polariton (SPhP) Raman signal can be enhanced by orders of magnitude. The high signal gain enables routine detailed characterisation of the SPhP peak on an individual NW level, revealing its polarisation properties and spectral shift under variation of the dielectric environment. This detailed characterisation was conducted using very low excitation power density despite high absorption of the excitation light in the NW material. The findings provide an effective way to use SPhP Raman scattering in the characterisation of dielectric NWs and the prospect of developing novel surface sensors

Upregulation of Toll-like receptor (TLR) expression and release of cytokines from P815 mast cells by GM-CSF

<p>Abstract</p> <p>Backgroud</p> <p>Recently, mast cells have been recognized to express several Toll-like receptors (TLRs) on their membrane surfaces, and granulocyte-macrophage colony-stimulating factor (GM-CSF) was reported to be able to alter expression of TLRs and cytokine production in neutrophils. However, whether GM-CSF modulates the expression of TLR and cytokine production in mast cells is not clear.</p> <p>Results</p> <p>Using flow cytometry and real time PCR techniques, we found that GM-CSF upregulated expression of TLR3 and TLR7 in P815 cells in a concentration dependent manner. GM-CSF also provoked approximately up to 2.4 and 2.3 fold increase in IL-13 and IL-6 release from P815 cells, respectively following 16 h incubation. GM-CSF induced IL-13 secretion, TLR3 and TLR7 expression appeared to be through activation of mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3K)/Akt signaling pathways, whereas GM-CSF elicited IL-6 release seemed via Akt signaling pathway. At 10 ng/ml, GM-CSF significantly enhanced R-848-induced IL-6 release from P815 cells.</p> <p>Conclusion</p> <p>The ability of GM-CSF in modulation of expression of TLR3 and TLR7 in P815 mast cells and in stimulation of IL-13 and IL-6 release from P815 mast cells in vitro suggests that GM-CSF might play an important role in enhancing the innate immune responses of mast cell to viral infection</p

Light-emitting GaAs nanowires on a flexible substrate

Semiconductor nanowire-based devices are among the most promising structures used to meet the current challenges of electronics, optics and photonics. Due to their high surface-to-volume ratio and excellent optical and electrical properties, devices with low power, high efficiency and high density can be created. This is of major importance for environmental issues and economic impact. Semiconductor nanowires have been used to fabricate high performance devices, including detectors, solar cells and transistors. Here, we demonstrate a technique for transferring large-area nanowire arrays to flexible substrates while retaining their excellent quantum efficiency in emission. Starting with a defect-free self-catalyzed molecular beam epitaxy (MBE) sample grown on a Si substrate, GaAs core–shell nanowires are embedded in a dielectric, removed by reactive ion etching and transferred to a plastic substrate. The original structural and optical properties, including the vertical orientation, of the nanowires are retained in the final plastic substrate structure. Nanowire emission is observed for all stages of the fabrication process, with a higher emission intensity observed for the final transferred structure, consistent with a reduction in nonradiative recombination via the modification of surface states. This transfer process could form the first critical step in the development of flexible nanowire-based light-emitting devices