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1. chinaXiv:201605.01566 [pdf]

SIMULATIONS OF THE SPATIAL AND TEMPORAL INVARIANCE IN THE SPECTRA OF GRADUAL SOLAR ENERGETIC PARTICLE EVENTS

Wang, Yang; Qin, Gang
Subjects: Geosciences >> Space Physics

The spatial and temporal invariance in the spectra of energetic particles in gradual solar events is reproduced in simulations. Based on a numerical solution of the focused transport equation, we obtain the intensity time profiles of solar energetic particles (SEPs) accelerated by an interplanetary shock in three-dimensional interplanetary space. The shock is treated as a moving source of energetic particles with a distribution function. The time profiles of particle fluxes. with different energies are calculated in the ecliptic at 1 AU. According to our model, we find that shock acceleration strength, parallel diffusion, and adiabatic cooling are the main factors in forming the spatial invariance in SEP spectra, and perpendicular diffusion is a secondary factor. In addition, the temporal invariance in SEP spectra is mainly due to the effects of adiabatic cooling. Furthermore, a spectra invariant region, which agrees with observations but is different from. the one suggested by Reames et al. is proposed based on our simulations.

submitted time 2016-05-12 Hits329Downloads191 Comment 0

2. chinaXiv:201605.01565 [pdf]

SIMULATIONS OF A GRADUAL SOLAR ENERGETIC PARTICLE EVENT OBSERVED BY HELIOS 1, HELIOS 2, AND IMP 8

Qin, Gang; Wang, Yang
Subjects: Geosciences >> Space Physics

In this work, a gradual solar energetic particle (SEP) event observed by multi-spacecraft has been simulated. The time profiles of SEP fluxes accelerated by an interplanetary shock in the three-dimensional interplanetary space are obtained by solving numerically the Fokker-Planck focused transport equation. The interplanetary shock is modeled as a moving source of energetic particles. By fitting the 1979 March 01 SEP fluxes observed by Helios 1, Helios 2, and IMP 8 with our simulations, we obtain the best parameters for the shock acceleration efficiency model. And we also find that the particle perpendicular diffusion coefficient with the level of similar to 1%-3% of parallel diffusion coefficient at 1 AU should be included. The reservoir phenomenon is reproduced in the simulations, and the longitudinal gradient of SEP fluxes in the decay phase, which is observed by three spacecraft at different locations, is more sensitive to the shock acceleration efficiency parameters than that is to the perpendicular diffusion coefficient.

submitted time 2016-05-12 Hits300Downloads177 Comment 0

3. chinaXiv:201605.01561 [pdf]

ESTIMATION OF THE RELEASE TIME OF SOLAR ENERGETIC PARTICLES NEAR THE SUN

Wang, Yang; Qin, Gang
Subjects: Geosciences >> Space Physics

This paper investigates the onset time of solar energetic particle (SEP) events with numerical simulations and analyzes the accuracy of the velocity dispersion analysis (VDA) method. Using a three-dimensional focused transport model, we calculate the fluxes of protons observed in the ecliptic at 1 AU in the energy range between 10 MeV and 80 MeV. In particular, three models are used to describe different SEP sources produced by flare or coronal shock, and the effects of particle perpendicular diffusion in the interplanetary space are also studied. We have the following findings. When the observer is disconnected from the source, the effects of perpendicular diffusion in the interplanetary space and particles propagating in the solar atmosphere have a significant influence on the VDA results. As a result, although the VDA method is valid with impulsive source duration, low background, and weak scattering in the interplanetary space or fast diffusion in the solar atmosphere, the method is not valid with gradual source duration, high background, or strong scattering.

submitted time 2016-05-12 Hits290Downloads147 Comment 0

4. chinaXiv:201605.01515 [pdf]

Intratumoral Delivery of IL-21 Overcomes Anti-Her2/Neu Resistance through Shifting Tumor-Associated Macrophages from M2 to M1 Phenotype

Xu, Meng; Liu, Mingyue; Du, Xuexiang; Li, Sirui; Li, Hang; Li, Xiaozhu; Li, Ying; Qin, Zhihai; Fu, Yang-Xin; Wang, Shengdian; Xu, Meng; Liu, Mingyue; Du, Xuexiang; Li, Sirui; Wang, Yang; Fu, Yang-Xin
Subjects: Biology >> Biophysics >> Immunology

Tumor resistance is a major hurdle to anti-Her2/neu Ab-based cancer therapy. Current strategies to overcome tumor resistance focus on tumor cell-intrinsic resistance. However, the extrinsic mechanisms, especially the tumor microenvironment, also play important roles in modulating the therapeutic response and resistance of the Ab. In this study, we demonstrate that tumor progression is highly associated with TAMs with immune-suppressive M2 phenotypes, and deletion of TAMs markedly enhanced the therapeutic effects of anti-Her2/neu Ab in a HER2/neu-dependent breast cancer cell TUBO model. Tumor local delivery of IL-21 can skew TAM polarization away from the M2 phenotype to a tumor-inhibiting M1 phenotype, which rapidly stimulates T cell responses against tumor and dramatically promotes the therapeutic effect of anti-Her2 Ab. Skewing of TAM polarization by IL-21 relies substantially on direct action of IL-21 on TAMs rather than stimulation of T and NK cells. Thus, our findings identify the abundant TAMs as a major extrinsic barrier for anti-Her2/neu Ab therapy and present a novel approach to combat this extrinsic resistance by tumor local delivery of IL-21 to skew TAM polarization. This study offers a therapeutic strategy to modulate the tumor microenvironment to overcome tumor-extrinsic resistance.

submitted time 2016-05-12 Hits1053Downloads506 Comment 0

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