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Articles by Lin Chen
Total Records ( 12 ) for Lin Chen
  Yan Liang , Bin Fang , Jiye Qian , Lin Chen , Chunyan Li and Ying Liu
 

The identification of non-cell objects in biological images is not a trivial task largely due to the difficulty in describing their characteristics in recognition systems. In order to better reduce the false positive rate caused by the presence of non-cell particles, we propose a novel approach using a local jet context features scheme combined with a two-tier object classification system. The newly proposed feature scheme, namely local jet context feature, integrates part of global features with the “local jet” features. The scheme aims to effectively describe the particle characteristics that are invariant to shift and rotation, and hence help to retain the critical shape information. The proposed two-tier particle classification strategy consists of a pre-recognition stage first and later a further filtering phase. Using the local jet context features coupled with a multi-class SVM classifier, the pre-recognition stage intends to assign the particles to their corresponding classes as many as possible. To further reduce the false positive particles, next a decision tree classifier based on shape-centered features is applied. Our experimental study shows that through the proposed two-tier classification strategy, we are able to achieve 85% of identification accuracy and 80% of F1 value in urinary particle recognition. The experiment results demonstrate that the proposed local jet context features are capable to discriminate particles in terms of shape and texture characteristics. Overall, the two-tier classification stage is found to be effective in reducing the false positive rate caused by non-cell particles.

  Xu Di , Jiangnan Xiao , Lin Chen and Jianjun Yu
  We have theoretically and experimentally investigated the timing offset estimation methods based on training symbol with three different structures (Two-segments, Four-segments and Eight-segments) in direct-detection (DD) optical orthogonal frequency division multiplexing (OOFDM) systems. The performance of the proposed method is evaluated in terms of mean and mean-square error (MSE) of timing offset estimation in one experimental system with 4 Gbits sec-1 DD-OOFDM signal transmission over 100 km standard Single Mode Fiber (SMF). The experimental results show that the two-segments timing offset estimation method has smaller MSE than the other methods and achieves higher acquisition probability of timing synchronization in DD-OOFDM transmission system.
  Guangqian Wen , Jiangnan Xiao , Zizheng Cao , Fan Li , Lin Chen and Jianjun Yu
  In a baseband direct-detected optical orthogonal frequency division multiplexing (DDO-OFDM) system, when the total transmitted power is constant, increasing the power of pilots can improve channel estimation accuracy but also increases the interference from them. Therefore, in order to obtain a best performance, the optimal ratio of pilot-to-total power should be given. In this letter, we compared different systems with different pilot power to total power ratios by simulations. The results showed that the power allocation with an optimal pilot power to total power ratio was found and the optimal power allocation obtained the most accurate channel estimation and the highest receiver sensitivity.
  Zhiwei Zheng , Ying Li , Jiangnan Xiao and Lin Chen
  This study proposes a novel scheme for realizing a cost-effective Base Station (BS) by using optical Local Oscillator (LO) and millimeter (mm)-wave signal distribution in a Radio-Over-Fiber (ROF) system. In the Central Station (CS), the optical LO and mm-wave signals were obtained via the Four-Wave Mixing (FWM) process in a Semiconductor Optical Amplifier (SOA). A 100/200 GHz optical interleaver was used to separate the optical LO and mm-wave signal in the BS and simplify the complexity of the filtering configuration. The 40 GHz optical LO and mm-wave distribution has been experimentally demonstrated in ROF systems by using the proposed scheme. The power penalty for downlink 40 GHz mm-wave signal was less than 1 dB.
  Yaoqiang Xiao and Lin Chen
  A novel full-duplex SSB-RoF system with 16 QAM-OFDM bidirectional links was proposed. Because the configurations of the used transmitters and receivers at the central office and base station are same, the BER curves were similar for back-to-back case. The results demonstrated, after transmission over 41 km SSMF-28, the OSNR value of the received downlink signal was 10.5 dB at BER = 10-3 which was slightly lower than the OSNR value of the upstream signal. Hence, 16 QAM-OFDM signals could be transmitted successfully over 41 km SSMF-28 for downlink and uplink application. It would be a competitive scheme for bidirectional 16 QAM-OFDM signals application in future RoF systems.
  Lin Chen
  Network capacity is one of basic problems of wireless networks, which reflects the asymptotic capacity when the number of nodes approaches infinite. Multi-channel hybrid wireless network, such as vehicular ad hoc network utilizes base station supports and multi-channel technologies. Due to randomly selecting the destination nodes, the performance of destination node may be constrained. For this kind of network sceneries, the mathematical analysis model is presented. Furthermore, the upper bound is estimated and the lower bound is constructed and calculated. The theoretical analysis results show that the time and channel resources are distributed according to the number of flows of nodes may improve the network performance. It provides one important reference for network system optimization.
  Yun Cheng , Minlei Xiao , Wenpi Wang and Lin Chen
  In this study, we have demonstrated two schemes for the generation of millimeter-wave (mm-wave) using optical frequency sixupler with a dual-electrode modulator (MZM). For scheme one and scheme two, the phase of RF signal is shifted by 180 degrees, drives the two electrodes of MZM at different bias levels and then high order sidebands is removed by optical bandpass filter. Theoretical analysis and simulation results show that the performance of millimeter-wave for scheme two is better than that of scheme one.
  Lin Chen , Jun Dai , Junjie Feng , Bing Fu and Haihong Pan
  To reduce time for collision detection among articulated models, the collision detection algorithm of Hybrid Bounding Volume Hierarchy Tree (HBVHT) was proposed to accelerate the speed of culling away triangles. The HBVHT was composed of two phases: A broad phase and a narrow phase. The broad phase consisted of Axis-Aligned Bounding Box (AABB) and the Bounding Volume (BV) was used to build a Multi-Level Hierarchy Tree (MLHT); the narrow phase was made up of the Oriented Bounding Box (OBB) hierarchy trees and triangles. Furthermore, according to the characteristic of hierarchical structure of the HBVHT, an improved cost function was given to analyze the performance of the HBVHT. Experiments were performed between two 6-DOF robots under the Open GL environment. Two robots with the same number of triangles moved with the same trajectory for the collision experiments. Experimental results show that the efficiency of HBVHT algorithm is higher than that of the RAPID and the other two HBVHTs with different structure. The results indicate that the HBVHT algorithm can effectively improve the efficiency of collision detection among the articulated model robots.
  Shan-Wu Dong , Yong Chen , Guang-Hua Liu , Lin Chen , Xue-Hua Zhao and Zhenyu Wang
  Background and Objective: Cadmium is a heavy metal that accumulates with time in different tissues of the body like central nervous system, kidney, liver etc. causing toxic effects especially to the brain and has a very long biological half-life. The objective of this study was to explore the neuroprotective effect of cadambine an indole alkaloid against cadmium-induced toxicity. Materials and Methods: Three cell lines namely N2A, SH-SY5Y and primary brain neonatal rat cells were used in this study. Cell viability and neuroprotection assays were assessed by MTT assay to determine the effect of cadmium and cadambine. Changes in the intracellular calcium levels, ROS and mitochondrial membrane potential were determined by flow cytometer. Western blotting was done to analyse the effects of cadmium and cadambine on pro-apoptotic and anti-apoptotic genes. Student’s t-test was used to compare the data. Results: In this study, it was confirmed that cadmium induced toxicity was reversed by cadambine. Cadambine increased the viability of cells treated with of cadmium induced toxicity. Furthermore, cadmium treatment led to generation of ROS, increased calcium levels, loss of MMP and increase in the expression of pro-apoptotic proteins. Interestingly, these effects was reversed by cadambine in primary brain neonatal rat cells. Conclusion: These findings led us to the conclusion that exposure to cadmium induces neurotoxic effects in brain and cadambine not only reversed the toxic effects of cadmium but also led to inhibition of cadmium-induced apoptosis. Based on this data, cadambine can further be investigated as potent neuroprotective agent.
  Lin Chen , Xiaoli Zeng and Xuewen Huang
  Background and Objective: Intraocular pressure (IOP) elevation is a major risk associated with glaucoma. Timolol is the most frequently used drug in the management of open-angle glaucoma (OG). The objective of this study was to compare the IOP-lowering effects of bimatoprost (BM) with timolol in a Chinese population with OG. Methodology: A total of 480 eyes of indoor patients suffering from OG (study group) and 50 normal eyes of indoor patients not suffering from OG (non-study group) were included in the study. The eyes of the treatment, control and non-study groups were treated with one drop of 0.03% w/v BM once daily, 0.5% w/v timolol maleate (TM) twice daily and water injection twice daily for 3 months, respectively. The IOP was measured at baseline and at 2, 6 weeks and 3 months of treatment. Conjunctival hyperemia, eye irritation, ocular hyperemia, foreign body sensation in eyes, corneal staining, heart rate and systolic and diastolic blood pressures were determined for the study group between baseline and 3 months of treatment. SPSS was use to analyze the data. Analysis of covariance was used to show better efficacy of BM compared with TM. One-way analysis of variance (ANOVA) and the Wilcoxon test were used for insignificant differences of ocular and systematic adverse effects. Results: There was a significant difference in IOP at baseline compared with the end of 3 months of BM (p = 0.00041) and TM (p = 0.0091) treatments. There was no significant difference between conjunctival hyperemia, eye irritation, ocular hyperemia, foreign body sensations in eyes, corneal staining, heart rate and systolic and diastolic blood pressures between baseline and at the end of 3 months of patients treated with BM. There was a significant difference for eyes reaching and maintaining an IOP<18 mmHg between the control group and the treatment group (p = 0.0478). Conclusion: The BM was more effective than timolol in lowering IOP over 3 months of treatment in open-angle glaucoma patients.
  LIN Chen , ZHOU Sheng-Lu , WU Shao-Hua and LIAO Fu-Qiang
  Soil erosion gradation is a robust and objective quantitative indicator of soil erosion intensity. Recent applications of soil erosion gradation have focused on monitoring soil erosion with models or simulation of soil erosion through gradation trends. However, soil erosion simulation accuracy is generally being reduced due to the rare consideration of the relationship between soil erosion gradation and erosion evolution. In this study, we investigated different soil erosion intensity grades to demonstrate their sensitivity to types and rates of erosion. Specifically, the objective was to define the relationship between soil erosion gradation and soil erosion evolution in Changting, an undeveloped area in Fujian Province, China, for four time intervals (1975, 1990, 1999, and 2006). The time series of erosion gradation were developed by modeling analysis with integration of several erosion indicators, and the relationships between the erosion grades and evolution types and rates were quantified. Comparison of the collapsing forces with natural and restoring forces based on human activity demonstrated that there existed an obvious spatial uncertainty in the erosion evolution types, both positive and negative succession coexisted, and the evolution rates were mostly influenced by the force of policy orientation. The impacts of these driving forces were eventually reflected in the erosion intensity gradation and erosion evolution. The correlation between the negative succession rate and erosion intensity gradation was weak and showed a poor contribution to the average succession rate, while the negative correlation between the positive succession rate and erosion intensity gradation would be increasingly clear as time passed.
  Lin Chen , J. Jillian Zhang and Xin- Yun Huang
  Cell migration is critical for animal development and physiological as well as pathological responses. One important step during cell migration is the formation of lamellipodia at the leading edge of migrating cells. Here we report that the second messenger cAMP inhibits the migration of mouse embryonic fibroblast cells and mouse breast tumor cells. cAMP acts downstream of the small GTPase Rac and interferes with the formation of lamellipodia. Moreover, cAMP decreases the phosphorylation of the myosin light chain at the leading edge of cells and increases the phosphorylation of the vasodilator-stimulated phosphoprotein. Together with our previous report of a positive role of another second messenger, cGMP, in lamellipodium formation, our data indicate that cAMP and cGMP play opposite roles in modulating lamellipodium formation.

 
 
 
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