Non-thermal emissions from outer magnetospheric accelerator of pulsars

We study non-thermal emission process in pulsar magnetospheric accelerator (outer gap). We discuss emission process in optical through γ-ray bands. We solve the dynamics in the outer gap in the magnetic meridional plane, which includes the rotation and magnetic axes. We calculate the spectrum of the curvature and synchrotron processes. Using a threedimensional geometrical model, we compute pulse profile and polarization characteristics. We compare the model results with the observations of the Vela pulsar and the Crab pulsar. We demonstrate that the observed multi-peak structure of the pulse profile observed by RXTE can be reproduced by the present study with the outward and inward emissions from the outer gap accelerator. The calculated polarization characteristics are in general consistent with the Crab optical data. © 2009 American Institute of Physics.published_or_final_versio

The Crab Optical/X/gamma-ray polarisation processes

published_or_final_versio

A three-dimensional model for the high-energy emissions from the Crab pulsar

We apply a three-dimensional outer gap accelerator model to the Crab pulsar for examining the light curve, phase-resolved spectrum and polarization. The curvature radiation process of the high-energy particles in the gap is calculated with an assumed three-dimensional structure of the accelerating electric field. We calculate the synchrotron self-inverse Compton process from the secondary pairs, which will be the observed emissions in optical to γ-ray regions. We compute radiation transfer for each radiated beam in three-dimensional geometry. © 2007 American Institute of Physics.published_or_final_versionThe 1st Glast Symposium, Stanford, CA., 5-8 February 2007. In AIP Conference Proceedings, 2007, v. 921, p. 423-42

Polarization of high-energy emissions from the Crab pulsar

abstract no. COSPAR2006-A-00603IT1-0059published_or_final_versio

Role of mitogen-activated protein kinase in Zn-BC-AM PDT-induced apoptosis in nasopharyngeal carcinoma cells

Photodynamic therapy (PDT) with a recently developed photosensitizer Zn-BC-AM was found to effectively induce apoptosis in a welldifferentiated nasopharyngeal carcinoma (NPC) HK-1 cell line. Sustained activation of p38 mitogen-activated protein kinase (MAPK) and cjun N-terminal kinase (JNK) as well as a transient increase in activation of extracellular signal-regulated kinase (ERK) were observed immediately after Zn-BC-AM PDT. A commonly used p38 MAPK/JNK pharmacological inhibitor PD169316 was found to reduce PDTinduced apoptosis of HK-1 cells. PD169316 also prevented the loss of Bcl-2 and Bcl-xL in PDT-treated HK-1 cells. However, inhibition of JNK with SP600125 had no effect on Zn-BC-AM PDT-induced apoptosis while inhibition of ERK with PD98059 or p38 MAPK with SB203580 significantly increased Zn-BC-AM PDT-induced apoptosis. Further study showed that knockdown of the p38b isoform with siRNA also increased Zn-BC-AM PDT-induced apoptosis, indicating that the anti-apoptotic effect of PD169316 in PDT-treated HK-1 cells was probably independent of p38 MAPK or JNK activation. Taken together, the results suggest that inhibition of p38b and ERK may enhance the therapeutic efficacy of Zn-BC-AM PDTon NPC cells. It should be noted that data only based on the use of PD169316 should be interpreted in caution. Copyright © 2010 John Wiley & Sons, Ltd.postprin

Efficient Computation of Distance Labeling for Decremental Updates in Large Dynamic Graphs

Since today's real-world graphs, such as social network graphs, are evolving all the time, it is of great importance to perform graph computations and analysis in these dynamic graphs. Due to the fact that many applications such as social network link analysis with the existence of inactive users need to handle failed links or nodes, decremental computation and maintenance for graphs is considered a challenging problem. Shortest path computation is one of the most fundamental operations for managing and analyzing large graphs. A number of indexing methods have been proposed to answer distance queries in static graphs. Unfortunately, there is little work on answering such queries for dynamic graphs. In this paper, we focus on the problem of computing the shortest path distance in dynamic graphs, particularly on decremental updates (i.e., edge deletions). We propose maintenance algorithms based on distance labeling, which can handle decremental updates efficiently. By exploiting properties of distance labeling in original graphs, we are able to efficiently maintain distance labeling for new graphs. We experimentally evaluate our algorithms using eleven real-world large graphs and confirm the effectiveness and efficiency of our approach. More specifically, our method can speed up index re-computation by up to an order of magnitude compared with the state-of-the-art method, Pruned Landmark Labeling (PLL)

Evaluation of coupled finite element/meshfree method for a robust full-scale crashworthiness simulation of railway vehicles

The crashworthiness of a railway vehicle relates to its passive safety performance. Due to mesh distortion and difficulty in controlling the hourglass energy, conventional finite element methods face great challenges in crashworthiness simulation of large-scale complex railway vehicle models. Meshfree methods such as element-free Galerkin method offer an alternative approach to overcome those limitations but have proved time-consuming. In this article, a coupled finite element/meshfree method is proposed to study the crashworthiness of railway vehicles. A representative scenario, in which the leading vehicle of a high-speed train impacts to a rigid wall, is simulated with the coupled finite element/element-free Galerkin method in LS-DYNA. We have compared the conventional finite element method and the coupled finite element/element-free Galerkin method with the simulation results of different levels of discretization. Our work showed that coupled finite element/element-free Galerkin method is a suitable alternative of finite element method to handle the nonlinear deformation in full-size railway vehicle crashworthiness simulation. The coupled method can reduce the hourglass energy in finite element simulation, to produce robust simulation