^(32)P-β射线致急性放射性皮肤损伤模型的建立及损伤机制

背景:急性放射性皮肤损伤的临床表现为反复发作的坏死性溃疡,其发病机制仍不完全清楚,建立合适的动物模型对其发病机制及预防治疗的研究具有重要临床价值。目的:建立急性β射线放射性皮肤损伤模型,初步探究其损伤机制。方法:69只SD大鼠随机分为30,45和^(60)Gyβ射线照射组(n=21)及对照组(n=6),采用^(32)P放射性核素对大鼠背部进行单次局部照射,对照组除不照射外其余操作与各照射组相同。造模后监测各组大鼠体质量,各照射组分别于照射后第7,15,30,45,60天各取3只大鼠切取皮肤组织观察损伤情况,包括皮肤外观、苏木精-伊红染色、Masson染色、透射电镜、TUNEL实验观察,另外采用免疫组化、Western Blot观察皮肤样本中Bcl-2、Bax及P53凋亡相关蛋白的表达。结果与结论:①照射后大鼠无意外死亡,体质量呈逐渐增加趋势;②大鼠皮肤出现不同程度的表皮层坏死、炎症细胞浸润、毛囊及附属器减少、胶原纤维断裂,以^(60)Gy、^(45)Gy表现明显,血清炎症因子白细胞介素6、肿瘤坏死因子α水平显著升高,呈剂量依赖性;③电镜结果显示细胞内出现不同程度的线粒体数量减少、空泡化以及核固缩,细胞凋亡程度呈现一定的剂量依赖性;④免疫组织化学及Western Blot结果显示,照射后皮肤组织P53及Bax蛋白表达增加,Bcl-2蛋白表达减弱,^(45)Gy、^(60)Gyβ射线组与30 Gyβ射线组相比差异有显著性意义(P<0.05);^(60)Gyβ射线组与^(45)Gyβ射线组相比差异有显著性意义(P<0.05);⑤结果提示,^(32)P放射性核素^(45)Gy及^(60)Gy照射大鼠背部可成功建立急性放射性皮肤损伤动物模型,其机制与凋亡相关因子P53、Bax上调及Bcl-2下调有关,该模型可为放射性皮肤损伤预防治疗及相关机制研究提供参考。

P2P与Grid的结合:P2P-Grid模型研究

分析P2P和网格技术各自的特点,对超级Peer内部的资源模型进行了讨论,提出了全局P2P-Grid网格资源组织模型。

P-Grid:一种高效的自组织P2P系统

P2P(peertopeer)技术在分布计算时代发挥着越来越重要的作用,但在数据管理方面,P2P的应用表现出较大的局限性。作为一种快速高效的P2P信息系统P-Grid,它能够极大地减少其它P2P系统所需要的网络带宽。P-Grid系统的构造和维护严格依照本地交互的随机算法,即使在不可靠的节点也能提供可靠的访问,并且能够较好地衡量存取和通信代价。

3-P-2[SS]结构FDM-3D打印机精度校准补偿算法

3-P-2[SS]机构FDM-3D打印机结构复杂,由于零部件加工和装配造成的结构误差,依靠三角函数解算动平台位置运动参数难以保证定位精度。通过对机构模型的逆运动学分析,推导了运动副垂直滑动计算公式,提出了一种动平台垂直误差补偿方法,对动平台在构建平台上运行区域进行了分析仿真,利用反距离加权插值算法,基于初始基准层打印高度采样,在机构运动约束条件下推导出动平台垂直精度补偿公式,通过实验验证了参数优化后设备成型过程中的定位精度获得很大提高,打印各厚度实验件的成型尺寸误差控制在±0.03mm以内,有效提高了成型件成型精度。

P2P-Grid环境中基于流言传播的资源查找方法研究

对两层结构的P2P-Grid网格模型进行了改进,在超级节点层上增加了分类节点层,即选择超级节点中性能较高的节点存放分类信息。给出了基于流言传播机制的分布式资源查找算法,该算法利用流言传播机制具有传播流言的兴趣随着重复收到某个流言而减少的特点,避免某个节点处理查找信息的负载过大,实现负载平衡,并与传统的泛洪算法进行了比较。模拟实验证明该算法能够缩短资源请求的响应时间,并且减少网格通信开销。

Mathematical Model Validation of Search Protocols in MP2P Networks

Broadcasting is a basic technique in Mobile ad-hoc network(MANET),and it refers to sending a packet from one node to every other node within the transmission range.Flooding is a type of broadcast where the received packet is retransmitted once by every node.The naive flooding technique,floods the network with query messages,while the random walk technique operates by contacting the subsets of every node’s neighbors at each step,thereby restricting the search space.One of the key challenges in an ad-hoc network is the resource or content discovery problem which is about locating the queried resource.Many earlier works have mainly focused on the simulation-based analysis of flooding,and its variants under a wired network.Although,there have been some empirical studies in peer-to-peer(P2P)networks,the analytical results are still lacking,especially in the context of P2P systems running over MANET.In this paper,we describe how P2P resource discovery protocols perform badly over MANETs.To address the limitations,we propose a new protocol named ABRW(Address Broadcast Random Walk),which is a lightweight search approach,designed considering the underlay topology aimed to better suit the unstructured architecture.We provide the mathematical model,measuring the performance of our proposed search scheme with different widely popular benchmarked search techniques.Further,we also derive three relevant search performance metrics,i.e.,mean no.of steps needed to find a resource,the probability of finding a resource,and the mean no.of message overhead.We validated the analytical expressions through simulations.The simulation results closely matched with our analyticalmodel,justifying our findings.Our proposed search algorithm under such highly dynamic self-evolving networks performed better,as it reduced the search latency,decreased the overall message overhead,and still equally had a good success rate.

METrust: A Mutual Evaluation-based Trust Model for P2P Networks

It is necessary to construct an effective trust model to build trust relationship between peers in peer-to-peer （P2P） network and enhance the security and reliability of P2P systems. The current trust models only focus on the consumers＇ evaluation to a transaction, which may be abused by malicious peers to exaggerate or slander the provider deliberately. In this paper, we propose a novel trust model based on mutual evaluation, called METrust, to suppress the peers＇ malicious behavior, such as dishonest evaluation and strategic attack. METrust considers the factors including mutual evaluation, similarity risk, time window, incentive, and punishment mechanism. The trust value is composed of the direct trust value and the recommendation trust value. In order to inhibit dishonest evaluation, both participants should give evaluation information based on peers＇ own experiences about the transaction while computing the direct trust value. In view of this, the mutual evaluation consistency factor and its time decay function are proposed. Besides, to reduce the risk of computing the recommendation trust based on the recommendations of friend peers, the similarity risk is introduced to measure the uncertainty of the similarity computing, while similarity is used to measure credibility. The experimental results show that METrust is effective, and it has advantages in the inhibition of the various malicious behaviors.

Cluster based hierarchical resource searching model in P2P network

For the problem of large network load generated by the Gnutella resource-searching model in Peer to Peer （P2P） network, a improved model to decrease the network expense is proposed, which establishes a duster in P2P network, auto-organizes logical layers, and applies a hybrid mechanism of directional searching and flooding. The performance analysis and simulation results show that the proposed hierarchical searching model has availably reduced the generated message load and that its searching-response time performance is as fairly good as that of the Gnutella model.

A process model on P2P lending

Background:Online peer-to-peer lending(P2P lending)is booming as the popularity of e-finance.To develop a conceptual model for the P2P lending process is great valuable for managers to tack the issues of marketing,management and operation.Methods:In this paper,we focus on the P2P lending process model and provide a comparative analysis comparing with traditional bank loan process.Results:Firstly,our model shows that the information flow in P2P lending is more frequent and transparent.Secondly,the model reveals that P2P lending uses a quite different credit audition method,which relies on information and the decision model in the P2P systems.Thirdly,the loan management is not complete normally in P2P lending,because most P2P companies do not have the post-loan records of borrowers.Conclusions:These findings inspire future studies and practices on P2P lending process and key technologies.

How the Information and Communications Technology Threaten Our Privacy： The Case of Email and P2P Propagation Models

With the rapid growth of information and communication technology （ICT）, the violation of information privacy has increased in recent years. The privacy concerns now re-emerge right because people perceives a threat from new ICT that are equipped with enhanced capabilities for surveillance, storage, retrieval, and diffusion of personal information. With the trend in the prevalence and the easy use of ICT, it is of necessary to pay much attention to the issue how the ICT can threaten the privacy of individuals on the Internet. While the Email and P2P （Peer-to-Peer） tools are the most popular ICT, this paper aims at understanding their respectively dissemination patterns in spreading of personal private information. To this purpose, this paper using dynamic model technique to simulate the pattern of sensitive or personal private information propagating situation. In this study, an Email propagation model and a Susceptible-lnfected-Removed （SIR） model are proposed to simulate the propagation patterns of Email and P2P network respectively. Knowing their dissemination patterns would be helpful for system designers, ICT manager, corporate IT personnel, educators, policy makers, and legislators to incorporate consciousness of social and ethical information issues into the protection of information privacy.

Epidemiological modeling of passive worm propagation on the P2P file-sharing network

The peer-to-peer（P2P） file-sharing network as a vehicle of disseminating files has become very popular. The appearance of dozens of kinds of passive worms on this network has, however, made it unsecured. This problem has been paid attention and a few of models for passive worm propagation has been presented. Unfortunately, the dynamic properties of this network are ignored in these models. Given the fact, the characteristics of both this network and the passive worm are identified, and on this basis a new mathematical model of passive worm propagation on the P2P network is presented in applying epidemiology in this paper. Note that the dynamic properties of this network are considered in the presented model. The model has been validated by large scale simulation experiments, which demonstrates that the presented model may be used for analyzing the behaviors of passive worms and predicting the trend of their propagation.

Modeling active worm propagation on the P2P network

This paper analyzes the characteristics of the Peer-to-Peer （P2P） active worm and its attacking mechanism, and then proposes a mathematical model of propagation of the P2P active worm applying Epidemiology. Based on the analysis on the protocols of realistic P2P systems, a software which can be used to simulate the P2P network environment and the propagation of P2P active worm is imple- mented in this paper. A large number of simulation experiments are performed using the developed simulation software. The results from these simulation experiments validate the proposed model, which means that the model can be used to analyze the spreading behaviors of the P2P active worm and predict its trend.

Peer selecting model based on FCM for wireless distributed P2P files sharing systems

IIn order to improve the performance of wireless distributed peer-to-peer(P2P)files sharing systems,a general system architecture and a novel peer selecting model based on fuzzy cognitive maps(FCM)are proposed in this paper.The new model provides an effective approach on choosing an optimal peer from several resource discovering results for the best file transfer.Compared with the traditional min-hops scheme that uses hops as the only selecting criterion,the proposed model uses FCM to investigate the complex relationships among various relative factors in wireless environments and gives an overall evaluation score on the candidate.It also has strong scalability for being independent of specified P2P resource discovering protocols.Furthermore,a complete implementation is explained in concrete modules.The simulation results show that the proposed model is effective and feasible compared with min-hops scheme,with the success transfer rate increased by at least 20% and transfer time improved as high as 34%.

P2P Model Based on Isolated Broadcast Domains

Resource location is the most important issue for Peer-to-Peer (P2P) system and flooding is the fundamental mechanism for unstructured P2P systems. Redundant messages will exponential growth with flooding scope increasing which severely influences the scalability of the system. In this paper, a new P2P model based on isolated broadcast domains is given to reduce the amount of redundant messages by limiting the radius of messages transmitted. Analysis and experiments show that this model can guarantee coverage of nodes and significantly reduce the amount of redundant messages generated.

一种基于层次化兴趣的非结构化P2P拓扑形成模型

在非结构化P2P系统中有两个根本性的问题需要研究:拓扑的自动生成和查询算法.其中前者更为重要:虽然查询算法通常是独立于拓扑结构的,但一个结构良好的拓扑会极大地改善查询算法的性能.提出一种基于层次化兴趣表达的拓扑生成模型(self adaptive community-based model,简称SACM).在这种模型里,每个节点由自身的资源整体类型倾向决定自己的兴趣(interest),并且采用树形结构来表达兴趣;然后节点由兴趣产生一个二进制序列的CID(community ID),CID将成为拓扑形成的主要依据——具有相近CID的节点能聚集成一个连通性较高的子图(社区).SACM不仅提供了生成聚类拓扑的算法,更为重要的是,它通过兴趣的定义及维护从统计上在资源和网络拓扑之间建立了联系.是否存在这种联系正是结构化P2P于非结构化P2P的本质区别.

雌激素及雌激素受体拮抗剂对乳腺癌信号传导通路中MEK-2和p-ERK病理形态的影响

目的:探讨乳腺癌中雌激素受体与细胞信号传导通路MAPK上游激酶MEK-2和下游激酶p-ERK的作用机制。方法:应用雌激素(雌二醇)与雌激素受体拮抗剂(三苯氧胺)诱导BCML-TA299小鼠原位移植乳腺癌组织,通过病理形态学、免疫组织化学法检测ERβ、MEK-2和p-ERK的表达。结果:雌二醇(E2)促进细胞增殖,核分裂多见,肿瘤有丰富的血管,第20天时肺组织中血管腔及心腔内可见大量瘤栓。E2可激活MEK-2,p-ERK明显上调,ERβ与其基因有协同作用;而三苯氧胺(TAM)抑制细胞增殖,癌细胞明显受到损伤,核碎裂、凋亡小体多见,可见多灶性变性坏死区。同时出现ERβ、MEK-2和p-ERK下调,亦有协同作用。三苯氧胺与环磷酰胺联合应用效应优于单药的应用(F=211.88,F=179.08,F=156.44;P<0.05)。结论:ERβ与MAPK信号途径中上游激酶MEK-2和下游激酶p-ERK关系密切,并有协同作用,是乳腺癌发展中重要的调节信号。

一种基于P2P的PKI体系

利用公钥基础设施PKI来解决网络通信中的信息安全问题日渐普及,但目前的PKI大多为集中式,存在扩展性较差、单点失效等缺陷。针对这些问题,本文提出了一种基于P2P的非集中式PKI体系,并在一个具体的P2P查询技术P-Grid的基础上给出了新体系的实现方法。

异补骨脂素对人皮肤角质形成细胞光老化模型p-ERK1/2及炎症因子影响

目的研究异补骨脂素对人皮肤角质形成细胞(Ha Ca T)光老化模型p-ERK1/2表达的影响及对光老化细胞分泌的白介素1α(IL-1α)、肿瘤坏死因子-α(TNF-α)等炎症因子的影响。方法使用照射强度为0.61m W·cm^(-2),照射时间为5min的UVB,建立光老化模型;雌二醇(阳性对照)及异补骨脂素(10^(-7),10^(-6),10-5 mol·L^(-1))处理光老化模型。MTT法检测细胞的活性;GSH、LDH及MDA试剂盒检测雌二醇及不同浓度异补骨脂素对细胞氧化酶活性的影响;Western Blot法检测雌二醇及不同浓度的异补骨脂素对细胞p-ERK1/2、IL-1α及TNF-α蛋白表达量的影响。结果与空白组比较,模型组GSH活性降低,LDH活性升高,MDA含量升高,p-ERK1/2、IL-1α及TNF-α蛋白表达量升高(P<0.01,P<0.05);与模型组比较,雌二醇及不同浓度异补骨脂素可以显著的升高GSH的活性,降低LDH活性,降低MDA含量,降低p-ERK1/2、IL-1α及TNF-α蛋白表达量(P<0.01,P<0.05)。结论异补骨脂素可通过抑制ERK磷酸化,抑制炎症因子的分泌。