f. rezazadeh

The network overhead and multiple networks disconnection faults are the main challenges of anonymous servers  implemented in VANETs. The block chain technology has been entered into the wide range of preserving privacy. The robust anonymity mechanism existence and the traceability of all transactions are the main advantages of this  technology. The primary model of the block chain was able to complete the process with the anonymity stored data. In distributed models, the authentication, storage and retrieval of transactions are applied by all user’s consensus. The asymmetric cryptography, preserves the identity anonymity and aggregating transactions of different users into a block which is ready to send, preserves the path anonymity. The proposed method is aimed to ensure anonymity by mounting the block chain on VANETs. Before delivering any transaction to the block chain, the risk of user’s privacy is high. To achieve low risk, we combine the graph processing methods with Silent Period, Cloaking-Region and  Dummy Node methods. The block chain simulation on VANET is driven by python and the anonymity risks are simulated with ARX. The results suggest that the block chain is stabled and the optimal risk reduction is achieved on the VANET.

Mast cells are initiating immune response and acting as first line of host defense against bacterial and parasitic infection. They are known to play an important role in allergic reaction, local homeostasis, inflammation and angiogenesis.

The aim of the present study was to evaluate the association between mast cell count and chronic periodontitis.

This case-control study was conducted on subjects referred to dentistry centers in Qazvin from 2004 to 2005. Periodontal parameters including probing depth, clinical attachment level, bleeding on probing, gingival and plaque indices were measured. Gingival specimens from 20 moderate to advanced chronic periodontitis sites (case group) and 18 healthy/ gingivitis sites (control group) in routine periodontal surgeries (flap and crown lengthening) were prepared. The specimens were examined after toluidine-blue staining for mast cells and Hematoxylin and Eosin staining for histological assessment of the inflammation. Mast cell counting and inflammation grading was performed 3 times by 2 observers in 5 micron length sections, using light microscope at 100 and 400 magnifications. Data were analyzed by T - test and ANOVA.

Mast cell count were 34.5±23.1 in case group and 13±9.8 in control group and the difference was statistically significant (P=0.001). In small grades of pathologic inflammation, mast cell count were 42.2±33.2 in case group and 8.4+5.4 in control group and the difference was statistically significant (P=0.04) as well. There was no relationship in high grades of inflammation.

The present study indicates that mast cell numbers in chronic periodontitis sites are more than healthy or gingivitis sites. The results of this study suggest more studies to clarify the role of mast cells in the pathogenesis of chronic periodontitis and also to evaluate the dynamic aspects of host defense simultaneously with other aspects of immune system.